TRPM Cation Channels
Cyclic Nucleotide Phosphodiesterases, Type 1
TRPC Cation Channels
Cyclic Nucleotide-Gated Cation Channels
Ion Channel Gating
TRPV Cation Channels
Cyclic Nucleotide Phosphodiesterases, Type 3
Molecular Sequence Data
Phosphoric Diester Hydrolases
Potassium Channels, Inwardly Rectifying
Calcium Channel Blockers
Cyclic Nucleotide Phosphodiesterases, Type 2
Amino Acid Sequence
Potassium Channel Blockers
Dibutyryl Cyclic GMP
Cyclic Nucleotide Phosphodiesterases, Type 4
Transient Receptor Potential Channels
Potassium Channels, Voltage-Gated
Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels
Calcium Channels, L-Type
TRPP Cation Channels
Acid Sensing Ion Channels
Potassium Channels, Calcium-Activated
Cyclic Nucleotide Phosphodiesterases, Type 7
Sodium Channel Blockers
Cyclic Nucleotide Phosphodiesterases, Type 5
Epithelial Sodium Channels
Shaker Superfamily of Potassium Channels
Dose-Response Relationship, Drug
Polymorphism, Single Nucleotide
Calcium Channels, N-Type
Large-Conductance Calcium-Activated Potassium Channels
Protein Structure, Tertiary
Calcium Channels, T-Type
Ether-A-Go-Go Potassium Channels
8-Bromo Cyclic Adenosine Monophosphate
Calcium Channel Agonists
Sequence Homology, Amino Acid
Cell Membrane Permeability
Kv1.2 Potassium Channel
Kv1.3 Potassium Channel
Kv1.1 Potassium Channel
Kv1.5 Potassium Channel
Degenerin Sodium Channels
Cation Transport Proteins
Cyclic AMP-Dependent Protein Kinases
Second Messenger Systems
Cyclic GMP-Dependent Protein Kinases
KCNQ Potassium Channels
Shab Potassium Channels
Organic Cation Transport Proteins
Receptors, Purinergic P2
Receptors, Purinergic P2X
Small-Conductance Calcium-Activated Potassium Channels
Organic Cation Transporter 1
Kv1.4 Potassium Channel
Receptors, Purinergic P2X4
Guanine Nucleotide Exchange Factors
Shaw Potassium Channels
Ryanodine Receptor Calcium Release Channel
Receptors, Purinergic P2X7
Shal Potassium Channels
G Protein-Coupled Inwardly-Rectifying Potassium Channels
KCNQ2 Potassium Channel
Sequence Homology, Nucleic Acid
Nucleic Acid Conformation
Sequence Analysis, DNA
Calcium Channels, P-Type
NAV1.5 Voltage-Gated Sodium Channel
Intermediate-Conductance Calcium-Activated Potassium Channels
Protein Structure, Secondary
Molecular characterization of the hyperpolarization-activated cation channel in rabbit heart sinoatrial node. (1/816)We cloned a cDNA (HAC4) that encodes the hyperpolarization-activated cation channel (If or Ih) by screening a rabbit sinoatrial (SA) node cDNA library using a fragment of rat brain If cDNA. HAC4 is composed of 1150 amino acid residues, and its cytoplasmic N- and C-terminal regions are longer than those of HAC1-3. The transmembrane region of HAC4 was most homologous to partially cloned mouse If BCNG-3 (96%), whereas the C-terminal region of HAC4 showed low homology to all HAC family members so far cloned. Northern blotting revealed that HAC4 mRNA was the most highly expressed in the SA node among the rabbit cardiac tissues examined. The electrophysiological properties of HAC4 were examined using the whole cell patch-clamp technique. In COS-7 cells transfected with HAC4 cDNA, hyperpolarizing voltage steps activated slowly developing inward currents. The half-maximal activation was obtained at -87.2 +/- 2.8 mV under control conditions and at -64.4 +/- 2.6 mV in the presence of intracellular 0.3 mM cAMP. The reversal potential was -34.2 +/- 0.9 mV in 140 mM Na+o and 5 mM K+o versus 10 mM Na+i and 145 mM K+i. These results indicate that HAC4 forms If in rabbit heart SA node. (+info)
Functional roles of aromatic residues in the ligand-binding domain of cyclic nucleotide-gated channels. (2/816)The ligand-binding domains of cyclic nucleotide-gated (CNG) channels show sequence homology to corresponding region(s) of the Escherichia coli catabolite gene-activator protein (CAP) and to the regulatory subunit of cAMP-dependent or cGMP-dependent protein kinases. The structure of CAP and that of a cAMP-dependent protein kinases regulatory subunit have been solved, prompting efforts to generate structural models for the binding domains in CNG channel. These models explicitly predicted that an aromatic residue in the CNG channel aligning with leucine 61 of CAP forms an interaction with the bound cyclic nucleotide. We tested this hypothesis by site-directed mutagenesis in a rat olfactory channel (rOCNC1) and a bovine rod photoreceptor channel (Brcng). We found that mutations at this site had only weak effects that were not specific to the aromatic or the hydrophobic nature of the substituted residue. This result weakens the hypothesis of a strong or specific interaction at this site. We also separately mutated most of the other aromatic residues in the binding domain to alanine; most of these mutations resulted in channels that either did not function or had only minor changes in sensitivity. However, replacing tyrosine 565 with alanine (Y565A) in rOCNC1 increased agonist sensitivity by approximately 10-fold and resulted in prominent spontaneous activities. Y565 presumably lies between two alpha helices in the binding domain; one of these, the C helix, probably rotates during channel activation. The position of Y565 at the "hinge" between the C helix and another portion of the binding domain, and the consequences of Y565 mutations, strongly suggest that this portion of the binding domain is involved in channel gating processes. (+info)
Single-channel kinetics of the rat olfactory cyclic nucleotide-gated channel expressed in Xenopus oocytes. (3/816)Cyclic nucleotide-gated channels are nonselective cation channels activated by intracellular cAMP and/or cGMP. It is not known how the binding of agonists opens the channel, or how the presumed four binding sites, one on each subunit, interact to generate cooperativity. We expressed the rat olfactory cyclic nucleotide-gated channel alpha subunit in Xenopus oocytes and recorded the single-channel currents. The channel had a single conductance state, and flickers at -60 mV showed the same power spectrum for cAMP and cGMP. At steady state, the distribution patterns of open and closed times were relatively simple, containing one or two exponential components. The conductance properties and the dwell-time distributions were adequately described by models that invoke only one or two binding events to open the channel, followed by an additional binding event that prolongs the openings and helps to explain apparent cooperativity. In a comparison between cAMP and cGMP, we find that cGMP has clearly higher binding affinity than cAMP, but only modestly higher probability of inducing the conformational transition that opens the channel. (+info)
Two pacemaker channels from human heart with profoundly different activation kinetics. (4/816)Cardiac pacemaking is produced by the slow diastolic depolarization phase of the action potential. The hyperpolarization-activated cation current (If) forms an important part of the pacemaker depolarization and consists of two kinetic components (fast and slow). Recently, three full-length cDNAs encoding hyperpolarization-activated and cyclic nucleotide-gated cation channels (HCN1-3) have been cloned from mouse brain. To elucidate the molecular identity of cardiac pacemaker channels, we screened a human heart cDNA library using a highly conserved neuronal HCN channel segment and identified two cDNAs encoding HCN channels. The hHCN2 cDNA codes for a protein of 889 amino acids. The HCN2 gene is localized on human chromosome 19p13.3 and contains eight exons spanning approximately 27 kb. The second cDNA, designated hHCN4, codes for a protein of 1203 amino acids. Northern blot and PCR analyses showed that both hHCN2 and hHCN4 are expressed in heart ventricle and atrium. When expressed in HEK 293 cells, either cDNA gives rise to hyperpolarization-activated cation currents with the hallmark features of native If. hHCN2 and hHCN4 currents differ profoundly from each other in their activation kinetics, being fast and slow, respectively. We thus conclude that hHCN2 and hHCN4 may underlie the fast and slow component of cardiac If, respectively. (+info)
Mechanism of allosteric modulation of rod cyclic nucleotide-gated channels. (5/816)The cyclic nucleotide-gated (CNG) channel of retinal rod photoreceptor cells is an allosteric protein whose activation is coupled to a conformational change in the ligand-binding site. The bovine rod CNG channel can be activated by a number of different agonists, including cGMP, cIMP, and cAMP. These agonists span three orders of magnitude in their equilibrium constants for the allosteric transition. We recorded single-channel currents at saturating cyclic nucleotide concentrations from the bovine rod CNG channel expressed in Xenopus oocytes as homomultimers of alpha subunits. The median open probability was 0.93 for cGMP, 0.47 for cIMP, and 0.01 for cAMP. The channels opened to a single conductance level of 26-30 pS at +80 mV. Using signal processing methods based on hidden Markov models, we determined that two closed and one open states are required to explain the gating at saturating ligand concentrations. We determined the maximum likelihood rate constants for two gating schemes containing two closed (denoted C) and one open (denoted O) states. For the C left and right arrow C left and right arrow O scheme, all rate constants were dependent on cyclic nucleotide. For the C left and right arrow O left and right arrow C scheme, the rate constants for only one of the transitions were cyclic nucleotide dependent. The opening rate constant was fastest for cGMP, intermediate for cIMP, and slowest for cAMP, while the closing rate constant was fastest for cAMP, intermediate for cIMP, and slowest for cGMP. We propose that interactions between the purine ring of the cyclic nucleotide and the binding domain are partially formed at the time of the transition state for the allosteric transition and serve to reduce the transition state energy and stabilize the activated conformation of the channel. When 1 microM Ni2+ was applied in addition to cyclic nucleotide, the open time increased markedly, and the closed time decreased slightly. The interactions between H420 and Ni2+ occur primarily after the transition state for the allosteric transition. (+info)
Sequence of events underlying the allosteric transition of rod cyclic nucleotide-gated channels. (6/816)Activation of cyclic nucleotide-gated (CNG) ion channels involves a conformational change in the channel protein referred to as the allosteric transition. The amino terminal region and the carboxyl terminal cyclic nucleotide-binding domain of CNG channels have been shown to be involved in the allosteric transition, but the sequence of molecular events occurring during the allosteric transition is unknown. We recorded single-channel currents from bovine rod CNG channels in which mutations had been introduced in the binding domain at position 604 and/or the rat olfactory CNG channel amino terminal region had been substituted for the bovine rod amino terminal region. Using a hidden Markov modeling approach, we analyzed the kinetics of these channels activated by saturating concentrations of cGMP, cIMP, and cAMP. We used thermodynamic mutant cycles to reveal an interaction during the allosteric transition between the purine ring of the cyclic nucleotides and the amino acid at position 604 in the binding site. We found that mutations at position 604 in the binding domain alter both the opening and closing rate constants for the allosteric transition, indicating that the interactions between the cyclic nucleotide and this amino acid are partially formed at the time of the transition state. In contrast, the amino terminal region affects primarily the closing rate constant for the allosteric transition, suggesting that the state-dependent stabilizing interactions between amino and carboxyl terminal regions are not formed at the time of the transition state for the allosteric transition. We propose that the sequence of events that occurs during the allosteric transition involves the formation of stabilizing interactions between the purine ring of the cyclic nucleotide and the amino acid at position 604 in the binding domain followed by the formation of stabilizing interdomain interactions. (+info)
Rod-type cyclic nucleotide-gated cation channel is expressed in vascular endothelium and vascular smooth muscle cells. (7/816)OBJECTIVES: Ca(++)-permeable nonselective cation channels mediate the entry of extracellular Ca++ in vascular endothelium. They are also partly responsible for Ca++ entry in vascular smooth muscle cells (SMCs). The molecular identities of these channels have not been identified. The aim of this study is to examine whether rod-type nucleotide-gated nonselective cation (CNG1) channel, a channel which has been molecularly cloned, is related to the nonselective channels in vascular cells. METHODS: We used RT-PCR, molecular cloning, northern Blot and in situ hybridization to examine the expression of CNG1 mRNA in a variety of guinea pig and rat blood vessels with different diameters and in cultured vascular endothelial cells and vascular smooth muscle cells. RESULTS: We have cloned a 402-bp partial cDNA of CNG1 channel from guinea pig mesenteric arteries. RT-PCR and southern blot results indicate that the CNG1 mRNA is expressed in both cultured vascular endothelial and cultured vascular SMCs. Northern blot revealed the transcripts of approximately 3.2 kb, approximately 5.0 kb, and approximately 1.8 kb in cultured endothelial cells. In situ hybridization yielded strong labeling in endothelium layer of aorta, medium-sized mesenteric arteries, and small mesenteric arteries. CONCLUSION: Our findings suggest a potential role of CNG protein for Ca++ entry in vascular endothelium and vascular smooth muscles. The high expression of CNG1 mRNA in the endothelium of medium-sized arteries and small-sized arteries implicates a possible involvement of CNG1 protein in the regulation of blood supply to different regions and in the regulation of arterial blood pressure. (+info)
Activity-dependent modulation of rod photoreceptor cyclic nucleotide-gated channels mediated by phosphorylation of a specific tyrosine residue. (8/816)Cyclic nucleotide-gated (CNG) channels are crucial for phototransduction in vertebrate rod photoreceptors. The cGMP sensitivity of these channels is modulated by diffusible intracellular messengers, including Ca2+/calmodulin, contributing to negative feedback during sensory adaptation. Membrane-associated protein tyrosine kinases and phosphatases also modulate rod CNG channels, but whether this results from direct changes in the phosphorylation state of the channel protein has been unclear. Here, we show that bovine rod CNG channel alpha-subunits (bRET) contain a tyrosine phosphorylation site crucial for modulation. bRET channels expressed in Xenopus oocytes exhibit modulation, whereas rat olfactory CNG channels (rOLF) do not. Chimeric channels reveal that differences in the C terminus, containing the cyclic nucleotide-binding domain, account for this difference. One specific tyrosine in bRET (Y498) appears to be crucial; replacement of this tyrosine in bRET curtails modulation, whereas installation into rOLF confers modulability. As the channel becomes dephosphorylated, there is an increase in the rate of spontaneous openings in the absence of ligand, indicating that changes in the phosphorylation state affect the allosteric gating equilibrium. Moreover, we find that dephosphorylation, which favors channel opening, requires open channels, whereas phosphorylation, which promotes channel closing, requires closed channels. Hence, modulation by changes in tyrosine phosphorylation is activity-dependent and may constitute a positive feedback mechanism, contrasting with negative feedback systems underlying adaptation. (+info)
There are several types of channelopathies, including:
1. Long QT syndrome: This is a condition that affects the ion channels in the heart, leading to abnormal heart rhythms and increased risk of sudden death.
2. Short QT syndrome: This is a rare condition that has the opposite effect of long QT syndrome, causing the heart to beat too quickly.
3. Catecholaminergic polymorphic ventricular tachycardia (CPVT): This is a rare disorder that affects the ion channels in the heart, leading to abnormal heart rhythms and increased risk of sudden death.
4. Brugada syndrome: This is a condition that affects the ion channels in the heart, leading to abnormal heart rhythms and increased risk of sudden death.
5. Wolff-Parkinson-White (WPW) syndrome: This is a condition that affects the ion channels in the heart, leading to abnormal heart rhythms and increased risk of sudden death.
6. Neuromuscular disorders: These are disorders that affect the nerve-muscle junction, leading to muscle weakness and wasting. Examples include muscular dystrophy and myasthenia gravis.
7. Dystrophinopathies: These are a group of disorders that affect the structure of muscle cells, leading to muscle weakness and wasting. Examples include Duchenne muscular dystrophy and Becker muscular dystrophy.
8. Myotonia: This is a condition that affects the muscles, causing them to become stiff and rigid.
9. Hyperkalemic periodic paralysis: This is a rare condition that causes muscle weakness and paralysis due to abnormal potassium levels in the body.
10. Hypokalemic periodic paralysis: This is a rare condition that causes muscle weakness and paralysis due to low potassium levels in the body.
11. Thyrotoxic periodic paralysis: This is a rare condition that causes muscle weakness and paralysis due to an overactive thyroid gland.
12. Hyperthyroidism: This is a condition where the thyroid gland becomes overactive, leading to increased heart rate, weight loss, and muscle weakness.
13. Hypothyroidism: This is a condition where the thyroid gland becomes underactive, leading to fatigue, weight gain, and muscle weakness.
14. Pituitary tumors: These are tumors that affect the pituitary gland, which regulates hormone production in the body.
15. Adrenal tumors: These are tumors that affect the adrenal glands, which produce hormones such as cortisol and aldosterone.
16. Carcinoid syndrome: This is a condition where cancer cells in the digestive system produce hormones that can cause muscle weakness and wasting.
17. Multiple endocrine neoplasia (MEN): This is a genetic disorder that affects the endocrine system and can cause tumors to grow in the thyroid, adrenal, and parathyroid glands.
These are just some of the many potential causes of muscle weakness. It's important to see a healthcare professional for an accurate diagnosis and appropriate treatment.
1) They share similarities with humans: Many animal species share similar biological and physiological characteristics with humans, making them useful for studying human diseases. For example, mice and rats are often used to study diseases such as diabetes, heart disease, and cancer because they have similar metabolic and cardiovascular systems to humans.
2) They can be genetically manipulated: Animal disease models can be genetically engineered to develop specific diseases or to model human genetic disorders. This allows researchers to study the progression of the disease and test potential treatments in a controlled environment.
3) They can be used to test drugs and therapies: Before new drugs or therapies are tested in humans, they are often first tested in animal models of disease. This allows researchers to assess the safety and efficacy of the treatment before moving on to human clinical trials.
4) They can provide insights into disease mechanisms: Studying disease models in animals can provide valuable insights into the underlying mechanisms of a particular disease. This information can then be used to develop new treatments or improve existing ones.
5) Reduces the need for human testing: Using animal disease models reduces the need for human testing, which can be time-consuming, expensive, and ethically challenging. However, it is important to note that animal models are not perfect substitutes for human subjects, and results obtained from animal studies may not always translate to humans.
6) They can be used to study infectious diseases: Animal disease models can be used to study infectious diseases such as HIV, TB, and malaria. These models allow researchers to understand how the disease is transmitted, how it progresses, and how it responds to treatment.
7) They can be used to study complex diseases: Animal disease models can be used to study complex diseases such as cancer, diabetes, and heart disease. These models allow researchers to understand the underlying mechanisms of the disease and test potential treatments.
8) They are cost-effective: Animal disease models are often less expensive than human clinical trials, making them a cost-effective way to conduct research.
9) They can be used to study drug delivery: Animal disease models can be used to study drug delivery and pharmacokinetics, which is important for developing new drugs and drug delivery systems.
10) They can be used to study aging: Animal disease models can be used to study the aging process and age-related diseases such as Alzheimer's and Parkinson's. This allows researchers to understand how aging contributes to disease and develop potential treatments.
Explanation: Genetic predisposition to disease is influenced by multiple factors, including the presence of inherited genetic mutations or variations, environmental factors, and lifestyle choices. The likelihood of developing a particular disease can be increased by inherited genetic mutations that affect the functioning of specific genes or biological pathways. For example, inherited mutations in the BRCA1 and BRCA2 genes increase the risk of developing breast and ovarian cancer.
The expression of genetic predisposition to disease can vary widely, and not all individuals with a genetic predisposition will develop the disease. Additionally, many factors can influence the likelihood of developing a particular disease, such as environmental exposures, lifestyle choices, and other health conditions.
Inheritance patterns: Genetic predisposition to disease can be inherited in an autosomal dominant, autosomal recessive, or multifactorial pattern, depending on the specific disease and the genetic mutations involved. Autosomal dominant inheritance means that a single copy of the mutated gene is enough to cause the disease, while autosomal recessive inheritance requires two copies of the mutated gene. Multifactorial inheritance involves multiple genes and environmental factors contributing to the development of the disease.
Examples of diseases with a known genetic predisposition:
1. Huntington's disease: An autosomal dominant disorder caused by an expansion of a CAG repeat in the Huntingtin gene, leading to progressive neurodegeneration and cognitive decline.
2. Cystic fibrosis: An autosomal recessive disorder caused by mutations in the CFTR gene, leading to respiratory and digestive problems.
3. BRCA1/2-related breast and ovarian cancer: An inherited increased risk of developing breast and ovarian cancer due to mutations in the BRCA1 or BRCA2 genes.
4. Sickle cell anemia: An autosomal recessive disorder caused by a point mutation in the HBB gene, leading to defective hemoglobin production and red blood cell sickling.
5. Type 1 diabetes: An autoimmune disease caused by a combination of genetic and environmental factors, including multiple genes in the HLA complex.
Understanding the genetic basis of disease can help with early detection, prevention, and treatment. For example, genetic testing can identify individuals who are at risk for certain diseases, allowing for earlier intervention and preventive measures. Additionally, understanding the genetic basis of a disease can inform the development of targeted therapies and personalized medicine."
The term "mucolipidoses" was coined by the American pediatrician and medical geneticist Dr. Victor A. McKusick in the 1960s to describe this group of diseases. The term is derived from the Greek words "muco-," meaning mucus, and "-lipido-," meaning fat, and "-osis," meaning condition or disease.
There are several types of mucolipidoses, including:
1. Mucolipidosis type I (MLI): This is the most common form of the disorder and is caused by a deficiency of the enzyme galactocerebrosidase (GALC).
2. Mucolipidosis type II (MLII): This form of the disorder is caused by a deficiency of the enzyme sulfatases, which are necessary for the breakdown of sulfated glycosaminoglycans (sGAGs).
3. Mucolipidosis type III (MLIII): This form of the disorder is caused by a deficiency of the enzyme acetyl-CoA:beta-glucoside ceramide beta-glucosidase (CERBGL), which is necessary for the breakdown of glycosphingolipids.
4. Mucolipidosis type IV (MLIV): This form of the disorder is caused by a deficiency of the enzyme glucocerebrosidase (GUCB), which is necessary for the breakdown of glucocerebroside, a type of glycosphingolipid.
Mucolipidoses are usually diagnosed by measuring the activity of the enzymes involved in glycosphingolipid metabolism in white blood cells or fibroblasts, and by molecular genetic analysis to identify mutations in the genes that code for these enzymes. Treatment is typically focused on managing the symptoms and may include physical therapy, speech therapy, and other supportive care measures. Bone marrow transplantation has been tried in some cases as a potential treatment for mucolipidosis, but the outcome has been variable.
Prognosis: The prognosis for mucolipidoses is generally poor, with most individuals with the disorder dying before the age of 10 years due to severe neurological and other complications. However, with appropriate management and supportive care, some individuals with milder forms of the disorder may survive into adulthood.
Epidemiology: Mucolipidoses are rare disorders, with an estimated prevalence of 1 in 100,000 to 1 in 200,000 births. They affect both males and females equally, and there is no known geographic or ethnic predilection.
Clinical features: The clinical features of mucolipidoses vary depending on the specific type of disorder and the severity of the mutation. Common features include:
* Delayed development and intellectual disability
* Vision loss or blindness
* Hearing loss or deafness
* Poor muscle tone and coordination
* Increased risk of infections
* Coarsening of facial features
* Enlarged liver and spleen
* Abnormalities of the heart, including ventricular septal defect and atrial septal defect
Diagnosis: Diagnosis of mucolipidoses is based on a combination of clinical features, laboratory tests, and genetic analysis. Laboratory tests may include measurement of enzyme activity in white blood cells, urine testing, and molecular genetic analysis.
Treatment and management: There is no cure for mucolipidoses, but treatment and management strategies can help manage the symptoms and improve quality of life. These may include:
* Physical therapy to improve muscle tone and coordination
* Speech therapy to improve communication skills
* Occupational therapy to improve daily living skills
* Anticonvulsant medications to control seizures
* Supportive care to manage infections and other complications
* Genetic counseling to discuss the risk of inheritance and options for family planning.
Prognosis: The prognosis for mucolipidoses varies depending on the specific type and severity of the condition. In general, the prognosis is poor for children with more severe forms of the disorder, while those with milder forms may have a better outlook. With appropriate management and supportive care, some individuals with mucolipidoses can lead relatively normal lives, while others may require ongoing medical care and assistance throughout their lives.
The QT interval is a measure of the time it takes for the ventricles to recover from each heartbeat and prepare for the next one. In people with LQTS, this recovery time is prolonged, which can disrupt the normal rhythm of the heart and increase the risk of arrhythmias.
LQTS is caused by mutations in genes that encode proteins involved in the cardiac ion channels, which regulate the flow of ions into and out of the heart muscle cells. These mutations can affect the normal functioning of the ion channels, leading to abnormalities in the electrical activity of the heart.
Symptoms of LQTS can include palpitations, fainting spells, and seizures. In some cases, LQTS can be diagnosed based on a family history of the condition or after a sudden death in an otherwise healthy individual. Other tests, such as an electrocardiogram (ECG), echocardiogram, and stress test, may also be used to confirm the diagnosis.
Treatment for LQTS typically involves medications that regulate the heart's rhythm and reduce the risk of arrhythmias. In some cases, an implantable cardioverter-defibrillator (ICD) may be recommended to monitor the heart's activity and deliver an electric shock if a potentially life-threatening arrhythmia is detected. Lifestyle modifications, such as avoiding stimuli that trigger symptoms and taking precautions during exercise and stress, may also be recommended.
In summary, Long QT syndrome is a rare inherited disorder that affects the electrical activity of the heart, leading to an abnormal prolongation of the QT interval and an increased risk of irregular and potentially life-threatening heart rhythms. It is important for individuals with LQTS to be closely monitored by a healthcare provider and to take precautions to manage their condition and reduce the risk of complications.
Examples of inborn errors of renal tubular transport include:
1. Cystinuria: This is a disorder that affects the reabsorption of cystine, an amino acid, in the renal tubules. It can lead to the formation of cystine stones in the kidneys.
2. Lowe syndrome: This is a rare genetic disorder that affects the transport of sodium and potassium ions across the renal tubules. It can cause a range of symptoms, including delayed development, intellectual disability, and seizures.
3. Glycine encephalopathy: This is a rare genetic disorder that affects the transport of glycine, an amino acid, across the renal tubules. It can cause a range of symptoms, including muscle weakness, developmental delays, and seizures.
4. Hartnup disease: This is a rare genetic disorder that affects the transport of tryptophan, an amino acid, across the renal tubules. It can cause a range of symptoms, including diarrhea, weight loss, and skin lesions.
5. Maple syrup urine disease: This is a rare genetic disorder that affects the transport of branched-chain amino acids (leucine, isoleucine, and valine) across the renal tubules. It can cause a range of symptoms, including seizures, developmental delays, and kidney damage.
Inborn errors of renal tubular transport can be diagnosed through a combination of clinical evaluation, laboratory tests, and genetic analysis. Treatment depends on the specific disorder and may include dietary modifications, medications, and dialysis. Early detection and treatment can help manage symptoms and prevent complications.
Insulinoma is a rare type of pancreatic tumor that produces excess insulin, leading to low blood sugar levels. These tumors are typically benign and can be treated with surgery or medication.
Insulinomas account for only about 5% of all pancreatic neuroendocrine tumors. They usually occur in the head of the pancreas and can cause a variety of symptoms, including:
1. Hypoglycemia (low blood sugar): The excess insulin produced by the tumor can cause blood sugar levels to drop too low, leading to symptoms such as shakiness, dizziness, confusion, and rapid heartbeat.
2. Hyperinsulinism (elevated insulin levels): In addition to hypoglycemia, insulinomas can also cause elevated insulin levels in the blood.
3. Abdominal pain: Insulinomas can cause abdominal pain and discomfort.
4. Weight loss: Patients with insulinomas may experience unexplained weight loss.
5. Nausea and vomiting: Some patients may experience nausea and vomiting due to the hypoglycemia or other symptoms caused by the tumor.
Insulinomas are usually diagnosed through a combination of imaging tests such as CT scans, MRI scans, and PET scans, and by measuring insulin and C-peptide levels in the blood. Treatment options for insulinomas include surgery to remove the tumor, medications to control hypoglycemia and hyperinsulinism, and somatostatin analogs to reduce hormone secretion.
Insulinoma is a rare and complex condition that requires careful management by a multidisciplinary team of healthcare professionals, including endocrinologists, surgeons, and radiologists. With appropriate treatment, most patients with insulinomas can experience long-term remission and improved quality of life.
Neuroblastoma is caused by a genetic mutation that affects the development and growth of nerve cells. The cancerous cells are often sensitive to chemotherapy, but they can be difficult to remove surgically because they are deeply embedded in the nervous system.
There are several different types of neuroblastoma, including:
1. Infantile neuroblastoma: This type of neuroblastoma occurs in children under the age of one and is often more aggressive than other types of the cancer.
2. Juvenile neuroblastoma: This type of neuroblastoma occurs in children between the ages of one and five and tends to be less aggressive than infantile neuroblastoma.
3. Adult neuroblastoma: This type of neuroblastoma occurs in adults and is rare.
4. Metastatic neuroblastoma: This type of neuroblastoma has spread to other parts of the body, such as the bones or liver.
Symptoms of neuroblastoma can vary depending on the location and size of the tumor, but they may include:
* Abdominal pain
* Loss of appetite
* Weight loss
* Bone pain
* Swelling in the abdomen or neck
* Increased heart rate
Diagnosis of neuroblastoma typically involves a combination of imaging tests, such as CT scans and MRI scans, and biopsies to confirm the presence of cancerous cells. Treatment for neuroblastoma usually involves a combination of chemotherapy, surgery, and radiation therapy. The prognosis for neuroblastoma varies depending on the type of cancer, the age of the child, and the stage of the disease. In general, the younger the child and the more aggressive the treatment, the better the prognosis.
There are several different types of pain, including:
1. Acute pain: This type of pain is sudden and severe, and it usually lasts for a short period of time. It can be caused by injuries, surgery, or other forms of tissue damage.
2. Chronic pain: This type of pain persists over a long period of time, often lasting more than 3 months. It can be caused by conditions such as arthritis, fibromyalgia, or nerve damage.
3. Neuropathic pain: This type of pain results from damage to the nervous system, and it can be characterized by burning, shooting, or stabbing sensations.
4. Visceral pain: This type of pain originates in the internal organs, and it can be difficult to localize.
5. Psychogenic pain: This type of pain is caused by psychological factors such as stress, anxiety, or depression.
The medical field uses a range of methods to assess and manage pain, including:
1. Pain rating scales: These are numerical scales that patients use to rate the intensity of their pain.
2. Pain diaries: These are records that patients keep to track their pain over time.
3. Clinical interviews: Healthcare providers use these to gather information about the patient's pain experience and other relevant symptoms.
4. Physical examination: This can help healthcare providers identify any underlying causes of pain, such as injuries or inflammation.
5. Imaging studies: These can be used to visualize the body and identify any structural abnormalities that may be contributing to the patient's pain.
6. Medications: There are a wide range of medications available to treat pain, including analgesics, nonsteroidal anti-inflammatory drugs (NSAIDs), and muscle relaxants.
7. Alternative therapies: These can include acupuncture, massage, and physical therapy.
8. Interventional procedures: These are minimally invasive procedures that can be used to treat pain, such as nerve blocks and spinal cord stimulation.
It is important for healthcare providers to approach pain management with a multi-modal approach, using a combination of these methods to address the physical, emotional, and social aspects of pain. By doing so, they can help improve the patient's quality of life and reduce their suffering.
There are two main types of myotonia:
1. Thomsen's disease: This is an inherited form of myotonia that affects the muscles of the face, neck, and limbs. It is caused by mutations in the CLCN1 gene and can be severe, causing difficulty with speaking, swallowing, and breathing.
2. Becker's muscular dystrophy: This is a form of muscular dystrophy that affects both the skeletal and cardiac muscles. It is caused by mutations in the DMPK gene and can cause myotonia, muscle weakness, and heart problems.
The symptoms of myotonia can vary depending on the severity of the condition and may include:
* Muscle stiffness and rigidity
* Spasms or twitches
* Difficulty with movement and mobility
* Fatigue and weakness
* Muscle wasting
Myotonia can be diagnosed through a combination of physical examination, medical history, and diagnostic tests such as electromyography (EMG) and muscle biopsy. There is no cure for myotonia, but treatment options may include:
* Physical therapy to improve movement and mobility
* Medications to relax muscles and reduce spasms
* Lifestyle modifications such as avoiding triggers and taking regular breaks to rest
* Surgery in severe cases to release or lengthen affected muscles.
It is important to note that myotonia can be a symptom of other underlying conditions, so proper diagnosis and management by a healthcare professional is essential to determine the best course of treatment.
Cyclic nucleotide-gated channel alpha 2
Cyclic nucleotide-gated channel alpha 3
Insect olfactory receptor
Bill S. Hansson
Cyclic nucleotide-gated channel alpha 4
Cyclic nucleotide-binding domain
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- The CNGB3 gene provides instructions for making one part (the beta subunit) of the cone photoreceptor cyclic nucleotide-gated (CNG) channel. (medlineplus.gov)
- There are at least four genetic causes of congenital ACHM, two of which are cyclic nucleotide-gated ion channels (ACHM2/ACHM3), a third the cone photoreceptor transducin ( GNAT2 , ACHM4), and the last unknown. (chemeurope.com)
- A subgroup of cyclic nucleotide-regulated ION CHANNELS within the superfamily of pore-loop cation channels. (bvsalud.org)
- Known genetic causes of this are mutations in the cone cell cyclic nucleotide-gated ion channels CNGA3 (ACHM2) and CNGB3 (ACHM3) as well as the cone cell transducin, GNAT2 (ACHM4). (chemeurope.com)
- Most CNGB3 gene mutations prevent the production of any functional beta subunit, which alters the structure of CNG channels. (medlineplus.gov)
- When expressed alone, CNGB3 cannot produce functional channels, whereas this is not the case for CNGA3 . (chemeurope.com)
- Coassembly of CNGA3 and CNGB3 produces channels with altered membrane expression, ion permeability ( Na + vs. K + and Ca 2+ ), relative efficacy of cAMP/cGMP activation, decreased outward rectification, current flickering, and sensitivity to block by L-cis-diltiazem . (chemeurope.com)
- CFTR is composed of approximately 1480 amino acids that encode a protein made up of a tandem repeate of transmembrane domains, each containing six transmembrane helices and a nucleotide binding domain. (justia.com)
- A subfamily of rhodopsin proteins that function as light-gated ion channels in GREEN ALGAE. (ouhsc.edu)
- While some mutations in CNGA3 result in truncated and, presumably, non-functional channels this is largely not the case. (chemeurope.com)
- While few mutations have received in-depth study, see table 1, at least one mutation does result in functional channels. (chemeurope.com)
- Functional evolution of eukaryotic ion channels and evolution of neuronal signaling and cell structure. (psu.edu)
- When light enters the eye, it triggers the closure of these channels, stopping the inward flow of cations. (medlineplus.gov)
- CNG channels are openings in the cell membrane that transport positively charged atoms (cations) into cells. (medlineplus.gov)
- CFTR is expressed in a variety of cells types, including absorptive and secretory epithelia cells, where it regulates anion flux across the membrane, as well as the activity of other ion channels and proteins. (justia.com)
- The two transmembrane domains are linked by a large, polar, regulatory (R)-domain with multiple phosphorylation sites that regulate channel activity and cellular trafficking. (justia.com)
- Because these CNG channels are specific to cones, rods are generally unaffected by this disorder. (medlineplus.gov)
- Complete achromatopsia is genetically heterogeneous and segregates with mutations in CNGA3 or CNGB3 genes, which respectively encode for alpha- and beta-subunits of the cyclic-nucleotide-gated (CNG) cation channel expressed in cone photoreceptors. (nih.gov)
- The severely truncated beta-subunit is likely to render a nonfunctional cone CNG channel and cause total colour blindness in this kindred. (nih.gov)
- The CNGB3 gene provides instructions for making one part (the beta subunit) of the cone photoreceptor cyclic nucleotide-gated (CNG) channel. (medlineplus.gov)
- Most CNGB3 gene mutations prevent the production of any functional beta subunit, which alters the structure of CNG channels. (medlineplus.gov)
- they express numerous voltage-gated sodium, calcium, potassium, and chloride channels and fire action potentials spontaneously, accompanied by a rise in intracellular calcium. (nih.gov)
- Cone cGMP-gated channel mutations and clinical findings in patients with achromatopsia, macular degeneration, and other hereditary cone diseases. (nih.gov)
- The ongoing experiments are also focused on characterization of electrical status of pituitary stem cells and single cell heterogeneity of electrical activity during development combined with analysis of expression of selected ion channel genes. (nih.gov)
- We also identified channels accounting for resting membrane potentials and spiking depolarization, as well as the mechanism for bursting and repolarization and channels involved, focusing on the role of calcium-controlled potassium channels in these processes. (nih.gov)
- The resulting channels are nonfunctional and prevent cones from carrying out phototransduction. (medlineplus.gov)
- SC, Mount DB, Gamba G. Molecular physiology of cation -coupled Cl- cotransport: the SLC12 family. (nih.gov)
- These channels are found exclusively in light-detecting (photoreceptor) cells called cones, which are located in a specialized tissue at the back of the eye known as the retina. (medlineplus.gov)
- This symposium will dissect and review the parcellation of cAMP signaling in the nervous system based on the anatomical diversity of expression of Gs-coupled GPCRs, cAMP sensors, cyclic nucleotide phosphodiesterases, and cyclic nucleotide-gated cation channels, and discuss how new imaging methods, high-throughput screening, and high-content screening have transformed this field, ripening it for translational research and drug discovery. (nih.gov)