Dihydropteridine Reductase
NADH, NADPH Oxidoreductases
Pteridines
Tetrahydropapaveroline
Phenylketonurias
Salsoline Alkaloids
Phenylalanine Hydroxylase
NAD
Phenylalanine
Liver
Sleep Deprivation
Seizures
Tablets
Electroencephalography
Epilepsy, Absence
Pamphlets
Anoxic function for the Escherichia coli flavohaemoglobin (Hmp): reversible binding of nitric oxide and reduction to nitrous oxide. (1/94)
The flavohaemoglobin Hmp of Escherichia coli is inducible by nitric oxide (NO) and provides protection both aerobically and anaerobically from inhibition of growth by NO and agents that cause nitrosative stress. Here we report rapid kinetic studies of NO binding to Fe(III) Hmp with a second order rate constant of 7.5 x 10(5) M(-1) s(-1) to generate a nitrosyl adduct that was stable anoxically but decayed in the presence of air to reform the Fe(III) protein. NO displaced CO bound to dithionite-reduced Hmp but, remarkably, CO recombined after only 2 s at room temperature indicative of NO reduction and dissociation from the haem. Addition of NO to anoxic NADH-reduced Hmp also generated a nitrosyl species which persisted while NADH was oxidised. These results are consistent with direct demonstration by membrane-inlet mass spectrometry of NO consumption and nitrous oxide production during anoxic incubation of NADH-reduced Hmp. The results demonstrate a new mechanism by which Hmp may eliminate NO under anoxic growth conditions. (+info)Effects of Enterococcus faecalis fsr genes on production of gelatinase and a serine protease and virulence. (2/94)
Three agr-like genes (fsrA, fsrB, and fsrC, for Enterococcus faecalis regulator) were found upstream of the previously reported gelatinase gene (gelE) and a downstream putative serine protease gene (sprE; accession number Z12296) of Enterococcus faecalis OG1RF. The deduced amino acid sequence of fsrA shows 26% identity and 38% similarity to Staphylococcus aureus AgrA (the response regulator of the accessory gene regulator system in the agr locus), FsrB shows 23% identity and 41% similarity to S. aureus AgrB, and FsrC shows 23% identity and 36% similarity to S. aureus AgrC (the sensor transducer of Agr system). Northern blot analysis suggested that gelE and sprE are cotranscribed and that fsrB and fsrC are also cotranscribed in OG1RF. Northern blot analysis of fsrA, fsrB, fsrC, gelE, and sprE insertion mutants showed that fsrB, fsrC, gelE, and sprE are not expressed in fsrA, fsrB, and fsrC mutants, while insertion in an open reading frame further upstream of fsrA did not effect the expression of these genes, suggesting that agr-like genes may be autoregulated and that they regulate gelE and sprE expression, as further confirmed by complementation of fsr gene mutations with a 6-kb fragment which contains all three fsr genes in the shuttle vector, pAT18. Testing of 95 other isolates of E. faecalis showed that 62% produced gelatinase (Gel(+)), while 91% (including all Gel(+) strains) hybridized to a gelE probe; 71% (including all Gel(+) strains) hybridized to an fsr probe, corroborating the conclusion that both gelE and fsr are necessary for gelatinase production. Testing of fsrA, fsrB, and sprE mutants in a mouse peritonitis model showed that sprE and agr-like gene mutants resulted in highly significantly prolonged survival compared to the parent strain OG1RF, a finding similar to what we had previously shown for a gelE mutant. These results suggest that sprE and agr-like genes contribute to the virulence of E. faecalis OG1RF in this model. (+info)Contrasting effects of N5-substituted tetrahydrobiopterin derivatives on phenylalanine hydroxylase, dihydropteridine reductase and nitric oxide synthase. (3/94)
Tetrahydrobiopterin [(6R)-5,6,7,8-tetrahydro-L-biopterin, H(4)biopterin] is one of several cofactors of nitric oxide synthases (EC 1.14.13.39). Here we compared the action of N(5)-substituted derivatives on recombinant rat neuronal nitric oxide synthase with their effects on dihydropteridine reductase (EC 1.6.99.7) and phenylalanine hydroxylase (EC 1.14.16.1),the well-studied classical H(4)biopterin-dependent reactions. H(4)biopterin substituted at N(5) with methyl, hydroxymethyl, formyl and acetyl groups were used. Substitution at N(5) occurs at a position critical to the redox cycle of the cofactor in phenylalanine hydroxylase/dihydropteridine reductase. We also included N(2)'-methyl H(4)biopterin, a derivative substituted at a position not directly involved in redox cycling, as a control. As compared with N(5)-methyl H(4)biopterin, N(5)-formyl H(4)biopterin bound with twice the capacity but stimulated nitric oxide synthase to a lesser extent. Depending on the substituent used, N(5)-substituted derivatives were redox-active: N(5)-methyl- and N(5)-hydroxyl methyl H(4)biopterin, but not N(5)-formyl- and N(5)-acetyl H(4)biopterin, reduced 2,6-dichlorophenol indophenol. N(5)-Substituted H(4)biopterin derivatives were not oxidized to products serving as substrates for dihydropteridine reductase and,depending on the substituent, were competitive inhibitors of phenylalanine hydroxylase: N(5)-methyl- and N(5)-hydroxymethyl H(4)biopterin inhibited phenylalanine hydroxylase, whereas N(5)-formyl- and N(5)-acetyl H(4)biopterin had no effect. Our data demonstrate differences in the mechanism of stimulation of phenylalanine hydroxylase and nitric oxide synthase by H(4)biopterin. They are compatible with a novel, non-classical, redox-active contribution of H(4)biopterin to the catalysis of the nitric oxide synthase reaction. (+info)Flavohemoglobin Hmp affords inducible protection for Escherichia coli respiration, catalyzed by cytochromes bo' or bd, from nitric oxide. (4/94)
Respiration of Escherichia coli catalyzed either by cytochrome bo' or bd is sensitive to micromolar extracellular NO; extensive, transient inhibition of respiration increases as dissolved oxygen tension in the medium decreases. At low oxygen concentrations (25-33 microm), the duration of inhibition of respiration by 9 microm NO is increased by mutation of either oxidase. Respiration of an hmp mutant defective in flavohemoglobin (Hmp) synthesis is extremely NO-sensitive (I(50) about 0.8 microm); conversely, cells pre-grown with sodium nitroprusside or overexpressing plasmid-borne hmp(+) are insensitive to 60 microm NO and have elevated levels of immunologically detectable Hmp. Purified Hmp consumes O(2) at a rate that is instantaneously and extensively (>10-fold) stimulated by NO due to NO oxygenase activity but, in the absence of NO, Hmp does not contribute measurably to cell oxygen consumption. Cyanide binds to Hmp (K(d) 3 microm). Concentrations of KCN (100 microm) that do not significantly inhibit cell respiration markedly suppress the protection of respiration from NO afforded by Hmp and abolish NO oxygenase activity of purified Hmp. The results demonstrate the role of Hmp in protecting respiration from NO stress and are discussed in relation to the energy metabolism of E. coli in natural O(2)-depleted environments. (+info)Molecular characterization of Drosophila melanogaster dihydropteridine reductase. (5/94)
Dihydropteridine reductase (DHPR) catalyzes the NAD(P)H-mediated reduction of quinonoid dihydropteridine as a part of pterin-dependent aromatic amino acid hydroxylation. We isolated a fragment of Drosophila DHPR gene by PCR using degenerate primers. By screening a cDNA library, we obtained full-length clones. The predicted amino acid sequence of the Drosophila DHPR protein was highly homologous to other species including human and mouse. In particular, the Tyr-(Xaa)(3)-Lys motif, known as the NAD(P)H binding domain, and most amino acids relevant to quinonoid dihydropteridine binding site are identical to human DHPR. The recombinant DHPR protein expressed in Escherichia coli showed DHPR enzyme activity. Northern blot analysis revealed two transcripts of 1.1 and 0.9 kb. Genomic DNA sequencing revealed that the gene consists of two exons interrupted by a single 96-bp intron. The two transcripts have alternative promoters, both having no putative TATA box or CAAT box, but sharing a common poly(A)(+) signal. The existence of two alternative promoters suggests that each transcript be regulated independently through different stimuli. Further study is needed to examine the expression and function of the two alternative transcripts. (+info)Flavohemoglobin, a globin with a peroxidase-like catalytic site. (6/94)
Biochemical studies of flavohemoglobin (Hmp) from Escherichia coli suggest that instead of aerobic oxygen delivery, a dioxygenase converts NO to NO3(-) and anaerobically, an NO reductase converts NO to N(2)O. To investigate the structural features underlying the chemical reactivity of Hmp, we have measured the resonance Raman spectra of the ligand-free ferric and ferrous protein and the CO derivatives of the ferrous protein. At neutral pH, the ferric protein has a five-coordinate high-spin heme, similar to peroxidases. In the ferrous protein, a strong iron-histidine stretching mode is present at 244 cm(-1). This frequency is much higher than that of any other globin discovered to date, although it is comparable to those of peroxidases, suggesting that the proximal histidine has imidazolate character. In the CO derivative, an open and a closed conformation were detected. The distal environment of the closed conformation is very polar, where the heme-bound CO strongly interacts with the B10 Tyr and/or the E7 Gln. These data demonstrate that the active site structure of Hmp is very similar to that of peroxidases and is tailored to perform oxygen chemistry. (+info)Escherichia coli flavohaemoglobin (Hmp) with equistoichiometric FAD and haem contents has a low affinity for dioxygen in the absence or presence of nitric oxide. (7/94)
A purification procedure for flavohaemoglobin Hmp (NO oxygenase) is described that gives high yields of protein with equistoichiometric haem and FAD contents. H(2)O(2) accumulated on NADH oxidation by the purified protein and in cell extracts with elevated Hmp contents. H(2)O(2) probably arose by dismutation from superoxide, which was also detectable during oxygen reduction; water was not a product. In the absence of agents that scavenge superoxide and peroxide, the mean K(m) for oxygen was 80 microM; the addition of 15 microM FAD decreased the K(m) for oxygen to 15 microM without a change in V(max) but catalysed cyanide-insensitive oxygen consumption, attributed to electron transfer from flavins to O(2). Purified Hmp consumed NO in the absence of added FAD (approx. 1 O(2) per NO), which is consistent with NO oxygenation. However, half-maximal rates of NO-stimulated O(2) consumption required approx. 47 microM O(2); NO removal was ineffective at physiologically relevant O(2) concentrations (below approx. 30 microM O(2)). On exhaustion of O(2), NO was removed by a cyanide-sensitive process attributed to NO reduction, with a turnover number approx. 1% of that for oxygenase activity. These results suggest that the ability of Hmp to detoxify NO might be compromised in hypoxic environments. (+info)Diagnosis of dopa-responsive dystonia and other tetrahydrobiopterin disorders by the study of biopterin metabolism in fibroblasts. (8/94)
BACKGROUND: Dopa-responsive dystonia (DRD) and tetrahydrobiopterin (BH4) defects are inherited disorders characterized by monoamine neurotransmitter deficiency with decreased activity of one of the BH4-metabolizing enzymes. The aim of the study was to determine the utility of cultured skin fibroblasts for the diagnosis of these diseases. METHODS: Neopterin and biopterin production and GTP cyclohydrolase I (GTPCH) activity were measured in cytokine-stimulated fibroblasts; 6-pyruvoyltetrahydropterin synthase (PTPS), sepiapterin reductase (SR), and dihydropteridine reductase (DHPR) activities were measured in unstimulated fibroblasts. We examined 8 patients with DRD, 3 with autosomal recessive GTPCH deficiency, 7 with PTPS deficiency, 3 with DHPR deficiency, and 49 controls (35 fibroblast and 14 amniocyte samples). RESULTS: Fibroblasts from patients with DRD and autosomal recessive GTPCH deficiency showed reduced GTPCH activity (15.4% and 30.7% of normal activity, respectively) compared with controls (P < 0.001). Neopterin production was very low and biopterin production was reduced in both disorders. PTPS- and DHPR-deficient cells showed no enzyme activities; in PTPS deficiency the pattern of pterin production was typical (neopterin, 334-734 pmol/mg; controls, 18-98 pmol/mg; biopterin, 0 pmol/mg; controls, 154-303 pmol/mg). Reference values of all enzyme activities and pterin production were measured in fibroblasts and also in amniocytes for prenatal diagnosis. CONCLUSIONS: Cultured skin fibroblasts are a useful tool in the diagnosis of BH4 deficiencies. Intracellular neopterin and biopterin concentrations and GTPCH activity in cytokine-stimulated fibroblasts are particularly helpful in diagnosing patients with DRD. (+info)Dihydropteridine reductase is an enzyme that plays a crucial role in the metabolism of certain amino acids, specifically phenylalanine and tyrosine. This enzyme is responsible for reducing dihydropteridines to tetrahydropteridines, which is a necessary step in the regeneration of tetrahydrobiopterin (BH4), an essential cofactor for the enzymes phenylalanine hydroxylase and tyrosine hydroxylase.
Phenylalanine hydroxylase and tyrosine hydroxylase are involved in the conversion of the amino acids phenylalanine and tyrosine to tyrosine and dopa, respectively. Without sufficient BH4, these enzymes cannot function properly, leading to an accumulation of phenylalanine and a decrease in the levels of important neurotransmitters such as dopamine, norepinephrine, and serotonin.
Deficiency in dihydropteridine reductase can lead to a rare genetic disorder known as dihydropteridine reductase deficiency (DPRD), which is characterized by elevated levels of phenylalanine and neurotransmitter imbalances, resulting in neurological symptoms such as developmental delay, seizures, and hypotonia. Treatment typically involves a low-phenylalanine diet and supplementation with BH4.
NADH, NADPH oxidoreductases are a class of enzymes that catalyze the redox reaction between NADH or NADPH and various electron acceptors. These enzymes play a crucial role in cellular metabolism by transferring electrons from NADH or NADPH to other molecules, which is essential for many biochemical reactions.
NADH (nicotinamide adenine dinucleotide hydrogen) and NADPH (nicotinamide adenine dinucleotide phosphate hydrogen) are coenzymes that act as electron carriers in redox reactions. They consist of a nicotinamide ring, which undergoes reduction or oxidation by accepting or donating electrons and a proton (H+).
NADH, NADPH oxidoreductases are classified based on their structure and mechanism of action. Some examples include:
1. Dehydrogenases: These enzymes catalyze the oxidation of NADH or NADPH to NAD+ or NADP+ while reducing an organic substrate. Examples include lactate dehydrogenase, alcohol dehydrogenase, and malate dehydrogenase.
2. Oxidases: These enzymes catalyze the oxidation of NADH or NADPH to NAD+ or NADP+ while reducing molecular oxygen (O2) to water (H2O). Examples include NADH oxidase and NADPH oxidase.
3. Reductases: These enzymes catalyze the reduction of various electron acceptors using NADH or NADPH as a source of electrons. Examples include glutathione reductase, thioredoxin reductase, and nitrate reductase.
Overall, NADH, NADPH oxidoreductases are essential for maintaining the redox balance in cells and play a critical role in various metabolic pathways, including energy production, detoxification, and biosynthesis.
Pteridines are a class of heterocyclic aromatic organic compounds that are structurally related to pterins, which contain a pyrimidine ring fused to a pyrazine ring. They are naturally occurring substances that can be found in various living organisms such as bacteria, fungi, plants, and animals.
Pteridines have several important biological functions. For instance, they play a crucial role in the synthesis of folate and biotin, which are essential cofactors for various metabolic reactions in the body. Additionally, some pteridines function as chromophores, contributing to the coloration of certain organisms such as butterflies and birds.
In medicine, pteridines have been studied for their potential therapeutic applications. For example, some synthetic pteridine derivatives have shown promising results in preclinical studies as antitumor, antiviral, and antibacterial agents. However, further research is needed to fully understand the medical implications of these compounds.
Tetrahydropapaveroline (THP) is not a medical term itself, but it is a chemical compound that has been studied in the field of medicine and biochemistry. THP is a bioactive alkaloid found in various plants, including opium poppy (Papaver somniferum), and is produced through the biosynthetic pathway involving tyrosine and dopamine.
In scientific research, THP has been investigated for its potential role in various physiological processes due to its interactions with neurotransmitters and receptors in the brain. Some studies suggest that THP may contribute to the development of tolerance and dependence associated with opioid use, as well as have implications in the regulation of mood and addiction.
However, it is essential to note that further research is required to fully understand the role and significance of Tetrahydropapaveroline in human health and disease.
Phenylketonurias (PKU) is a genetic disorder characterized by the body's inability to properly metabolize the amino acid phenylalanine, due to a deficiency of the enzyme phenylalanine hydroxylase. This results in a buildup of phenylalanine in the blood and other tissues, which can cause serious neurological problems if left untreated.
The condition is typically detected through newborn screening and can be managed through a strict diet that limits the intake of phenylalanine. If left untreated, PKU can lead to intellectual disability, seizures, behavioral problems, and other serious health issues. In some cases, medication or a liver transplant may also be necessary to manage the condition.
Salsoline alkaloids are a type of natural toxin found in some plants, particularly in the family Solanaceae, which includes nightshades. These alkaloids consist of several compounds, including salsoline, salsolidine, and isosalsolidine. They can be found in various plants such as *Salsola tuberculatiformis*, *Salsola kali*, and *Rhizothera americana*. Salsoline alkaloids have been reported to have a range of pharmacological effects, including vasoconstrictive, diuretic, and stimulant properties. However, they can also be toxic in high concentrations, causing symptoms such as nausea, vomiting, and seizures.
Biopterin is a type of pteridine compound that acts as a cofactor in various biological reactions, particularly in the metabolism of amino acids such as phenylalanine and tyrosine. It plays a crucial role in the production of neurotransmitters like dopamine, serotonin, and noradrenaline. Biopterin exists in two major forms: tetrahydrobiopterin (BH4) and dihydrobiopterin (BH2). BH4 is the active form that participates in enzymatic reactions, while BH2 is an oxidized form that can be reduced back to BH4 by the action of dihydrobiopterin reductase.
Deficiencies in biopterin metabolism have been linked to several neurological disorders, including phenylketonuria (PKU), dopamine-responsive dystonia, and certain forms of autism. In these conditions, the impaired synthesis or recycling of biopterin can lead to reduced levels of neurotransmitters, causing various neurological symptoms.
Pterins are a group of naturally occurring pigments that are derived from purines. They are widely distributed in various organisms, including bacteria, fungi, and animals. In humans, pterins are primarily found in the eye, skin, and hair. Some pterins have been found to play important roles as cofactors in enzymatic reactions and as electron carriers in metabolic pathways.
Abnormal levels of certain pterins can be indicative of genetic disorders or other medical conditions. For example, an excess of biopterin, a type of pterin, is associated with phenylketonuria (PKU), a genetic disorder that affects the body's ability to metabolize the amino acid phenylalanine. Similarly, low levels of neopterin, another type of pterin, can be indicative of immune system dysfunction or certain types of cancer.
Medical professionals may measure pterin levels in blood, urine, or other bodily fluids to help diagnose and monitor these conditions.
2,6-Dichloroindophenol is a chemical compound that is used as an indicator in various analytical procedures, particularly in the field of biochemistry and microbiology. It is a derivative of indophenol, which contains two chlorine atoms at the 2nd and 6th positions of the benzene ring.
The chemical formula for 2,6-Dichloroindophenol is C8H6Cl2O2. This compound is a deep blue color in its oxidized state and turns colorless when reduced. The reduction potential of this compound makes it useful as an indicator in various redox reactions, including the determination of the concentration of reducing agents such as ascorbic acid (vitamin C) and other antioxidants.
It is important to note that 2,6-Dichloroindophenol is a hazardous chemical and should be handled with care. It can cause skin and eye irritation, and prolonged exposure may lead to more serious health effects. Therefore, it is essential to follow proper safety precautions when working with this compound.
Phenylalanine Hydroxylase (PAH) is an enzyme that plays a crucial role in the metabolism of the essential amino acid phenylalanine. This enzyme is primarily found in the liver and is responsible for converting phenylalanine into tyrosine, another amino acid. PAH requires a cofactor called tetrahydrobiopterin (BH4) to function properly.
Defects or mutations in the gene that encodes PAH can lead to a genetic disorder known as Phenylketonuria (PKU). In PKU, the activity of PAH is significantly reduced or absent, causing an accumulation of phenylalanine in the body. If left untreated, this condition can result in severe neurological damage and intellectual disability due to the toxic effects of high phenylalanine levels on the developing brain. A strict low-phenylalanine diet and regular monitoring of blood phenylalanine levels are essential for managing PKU and preventing associated complications.
Adrenochrome is a chemical compound that is formed when adrenaline (epinephrine) is oxidized. It is not a naturally occurring hormone or neurotransmitter, but rather a byproduct of the breakdown of these substances. The existence of adrenochrome in the human body is controversial and its effects on the human brain are not well understood.
In popular culture, adrenochrome has been associated with theories about its psychoactive properties and alleged use as a drug in illegal or illicit activities. However, there is no scientific evidence to support these claims and they should be regarded with skepticism. The misinformation surrounding adrenochrome may have originated from Hunter S. Thompson's book "Fear and Loathing in Las Vegas," where it was described as a drug that produces intense hallucinations and feelings of euphoria. However, this portrayal is not based on any scientific evidence and should be considered fiction.
NAD (Nicotinamide Adenine Dinucleotide) is a coenzyme found in all living cells. It plays an essential role in cellular metabolism, particularly in redox reactions, where it acts as an electron carrier. NAD exists in two forms: NAD+, which accepts electrons and becomes reduced to NADH. This pairing of NAD+/NADH is involved in many fundamental biological processes such as generating energy in the form of ATP during cellular respiration, and serving as a critical cofactor for various enzymes that regulate cellular functions like DNA repair, gene expression, and cell death.
Maintaining optimal levels of NAD+/NADH is crucial for overall health and longevity, as it declines with age and in certain disease states. Therefore, strategies to boost NAD+ levels are being actively researched for their potential therapeutic benefits in various conditions such as aging, neurodegenerative disorders, and metabolic diseases.
Phenylalanine is an essential amino acid, meaning it cannot be produced by the human body and must be obtained through diet or supplementation. It's one of the building blocks of proteins and is necessary for the production of various molecules in the body, such as neurotransmitters (chemical messengers in the brain).
Phenylalanine has two forms: L-phenylalanine and D-phenylalanine. L-phenylalanine is the form found in proteins and is used by the body for protein synthesis, while D-phenylalanine has limited use in humans and is not involved in protein synthesis.
Individuals with a rare genetic disorder called phenylketonuria (PKU) must follow a low-phenylalanine diet or take special medical foods because they are unable to metabolize phenylalanine properly, leading to its buildup in the body and potential neurological damage.
The liver is a large, solid organ located in the upper right portion of the abdomen, beneath the diaphragm and above the stomach. It plays a vital role in several bodily functions, including:
1. Metabolism: The liver helps to metabolize carbohydrates, fats, and proteins from the food we eat into energy and nutrients that our bodies can use.
2. Detoxification: The liver detoxifies harmful substances in the body by breaking them down into less toxic forms or excreting them through bile.
3. Synthesis: The liver synthesizes important proteins, such as albumin and clotting factors, that are necessary for proper bodily function.
4. Storage: The liver stores glucose, vitamins, and minerals that can be released when the body needs them.
5. Bile production: The liver produces bile, a digestive juice that helps to break down fats in the small intestine.
6. Immune function: The liver plays a role in the immune system by filtering out bacteria and other harmful substances from the blood.
Overall, the liver is an essential organ that plays a critical role in maintaining overall health and well-being.
Sleep deprivation is a condition that occurs when an individual fails to get sufficient quality sleep or the recommended amount of sleep, typically 7-9 hours for adults. This can lead to various physical and mental health issues. It can be acute, lasting for one night or a few days, or chronic, persisting over a longer period.
The consequences of sleep deprivation include:
1. Fatigue and lack of energy
2. Difficulty concentrating or remembering things
3. Mood changes, such as irritability or depression
4. Weakened immune system
5. Increased appetite and potential weight gain
6. Higher risk of accidents due to decreased reaction time
7. Health problems like high blood pressure, diabetes, and heart disease over time
Sleep deprivation can be caused by various factors, including stress, shift work, sleep disorders like insomnia or sleep apnea, poor sleep hygiene, and certain medications. It's essential to address the underlying causes of sleep deprivation to ensure proper rest and overall well-being.
A seizure is an uncontrolled, abnormal firing of neurons (brain cells) that can cause various symptoms such as convulsions, loss of consciousness, altered awareness, or changes in behavior. Seizures can be caused by a variety of factors including epilepsy, brain injury, infection, toxic substances, or genetic disorders. They can also occur without any identifiable cause, known as idiopathic seizures. Seizures are a medical emergency and require immediate attention.
In the context of medical terminology, tablets refer to pharmaceutical dosage forms that contain various active ingredients. They are often manufactured in a solid, compressed form and can be administered orally. Tablets may come in different shapes, sizes, colors, and flavors, depending on their intended use and the manufacturer's specifications.
Some tablets are designed to disintegrate or dissolve quickly in the mouth, making them easier to swallow, while others are formulated to release their active ingredients slowly over time, allowing for extended drug delivery. These types of tablets are known as sustained-release or controlled-release tablets.
Tablets may contain a single active ingredient or a combination of several ingredients, depending on the intended therapeutic effect. They are typically manufactured using a variety of excipients, such as binders, fillers, and disintegrants, which help to hold the tablet together and ensure that it breaks down properly when ingested.
Overall, tablets are a convenient and widely used dosage form for administering medications, offering patients an easy-to-use and often palatable option for receiving their prescribed treatments.
Electroencephalography (EEG) is a medical procedure that records electrical activity in the brain. It uses small, metal discs called electrodes, which are attached to the scalp with paste or a specialized cap. These electrodes detect tiny electrical charges that result from the activity of brain cells, and the EEG machine then amplifies and records these signals.
EEG is used to diagnose various conditions related to the brain, such as seizures, sleep disorders, head injuries, infections, and degenerative diseases like Alzheimer's or Parkinson's. It can also be used during surgery to monitor brain activity and ensure that surgical procedures do not interfere with vital functions.
EEG is a safe and non-invasive procedure that typically takes about 30 minutes to an hour to complete, although longer recordings may be necessary in some cases. Patients are usually asked to relax and remain still during the test, as movement can affect the quality of the recording.
Absence epilepsy is a type of epilepsy characterized by recurrent brief episodes of "absences," or staring spells, that can last from a few seconds to several minutes. These episodes are often accompanied by subtle body movements such as lip smacking or eyelid flutters. Absence epilepsy is most commonly diagnosed in children and adolescents, and it is more common in girls than boys.
The seizures in absence epilepsy are caused by abnormal electrical activity in the brain, specifically in a part of the brain called the cortex. These abnormal electrical discharges occur in a pattern that involves both sides of the brain simultaneously. This differs from other types of epilepsy, which may involve only one side of the brain or specific areas within a single hemisphere.
Absence seizures are typically brief and do not cause confusion or disorientation after they end. However, if they occur frequently, they can interfere with learning and social development. In some cases, absence epilepsy may be associated with other types of seizures, such as generalized tonic-clonic (grand mal) seizures or myoclonic jerks.
The diagnosis of absence epilepsy is usually made based on the characteristic symptoms and the results of an electroencephalogram (EEG), which can detect the abnormal electrical activity in the brain during a seizure. Treatment typically involves medication to control the seizures, such as ethosuximide or valproic acid. In some cases, a ketogenic diet may also be recommended as an alternative treatment option.
I'm sorry for any confusion, but "pamphlets" is not a medical term. It refers to a small paper booklet or leaflet that can be used to provide information on various topics, including non-medical subjects. If you have any questions about medical terminology or concepts, I'd be happy to help with those!
Neurology is a branch of medicine that deals with the study and treatment of diseases and disorders of the nervous system, which includes the brain, spinal cord, peripheral nerves, muscles, and autonomic nervous system. Neurologists are medical doctors who specialize in this field, diagnosing and treating conditions such as stroke, Alzheimer's disease, epilepsy, Parkinson's disease, multiple sclerosis, and various types of headaches and pain disorders. They use a variety of diagnostic tests, including imaging studies like MRI and CT scans, electrophysiological tests like EEG and EMG, and laboratory tests to evaluate nerve function and identify any underlying conditions or abnormalities. Treatment options may include medication, surgery, rehabilitation, or lifestyle modifications.
Dihydropteridine reductase deficiency
6,7-dihydropteridine reductase
QDPR
Tetrahydrobiopterin deficiency
Sepiapterin reductase
Tetrahydrobiopterin
Tyrosine hydroxylase
Adiponectin
Queuine
DHPR
Nitroreductase
Microcephaly
International Working Group on Neurotransmitter Related Disorders
Hyperphenylalaninemia
List of diseases (H)
Chromosome 4
List of diseases (D)
Dopamine-responsive dystonia
List of MeSH codes (D08)
List of EC numbers (EC 1)
Dihydropteridine reductase deficiency - Wikipedia
Mutations in the BH4-metabolizing genes GTP cyclohydrolase I, 6-pyruvoyl-tetrahydropterin synthase, sepiapterin reductase,...
MedlinePlus: Genes: Q
Thieme E-Journals - Journal of Pediatric Biochemistry / Abstract
Single-cell transcriptomic analysis of Alzheimer's disease | Nature
metabolic pathway pertinent to the brain - Ontology Report - Rat Genome Database
BH4 Deficiency (Tetrahydrobiopterin Deficiency): Background, Pathophysiology, Epidemiology
KoreaMed
WikiGenes - Neurologic Manifestations
Trexall, Otrexup (methotrexate) dosing, indications, interactions, adverse effects, and more
Feedback on Soma Side Effects and Usage, page 17 - AskDocWeb.com
Phenylketonuria (PKU) - Pediatrics - Merck Manuals Professional Edition
DR Wilfred L. F. Armarego - Researchers - ANU
Optometry - Research Outputs
- Aston Research Explorer
RCSB PDB - MES Ligand Summary Page
Spectrum of common and rare small molecule inborn errors of metabolism diagnosed in a tertiary care centre.
Screening Procedures: Variations in Diagnostic Criteria & Followup | NICHD - Eunice Kennedy Shriver National Institute of Child...
HALLMARK MTORC1 SIGNALING
GSE17721 CTRL VS POLYIC 4H BMDC UP
Celia Fern��ndez. Curriculum. Universidad de Navarra
Nitrite reductases. Medical search
Specific PHGKB|Rare Diseases PHGKB|PHGKB
SZGR2
Understanding Phenylketonuria (PKU): Causes, Symptoms, and Management
Olink Target 96 Mouse Exploratory Panel（小鼠探索）
SZGR2
Similarities of Characterized Proteins
Disorders of Amino Acid Metabolism, Organic Acidaemias and Urea Cycle Disorders | Oncohema Key
ExplorEnz: EC 1.14.16.4
DHPR5
- Tetrahydrobiopterin (BH(4)) deficiencies are a highly heterogeneous group of disorders with several hundred patients, and so far a total of 193 different mutant alleles or molecular lesions identified in the GTP cyclohydrolase I (GTPCH), 6-pyruvoyl-tetrahydropterin synthase (PTPS), sepiapterin reductase (SR), carbinolamine-4a-dehydratase (PCD), or dihydropteridine reductase (DHPR) genes. (qxmd.com)
- a) Studies of dihydropteridine reductase (DHPR) from human and other sources. (edu.au)
- With regard to BH4 deficiencies, more than 190 different mutant alleles or molecular lesions have been identified, including in the genes for guanosine triphosphate cyclohydrolase (GCH), 6-pyruvoyl-tetrahydropterin synthase (PTPS), sepiapterin reductase (SR), carbinolamine-4a-dehydratase (PCD), and dihydropteridine reductase (DHPR). (medscape.com)
- PKU is customarily caused by a deficiency of the phenylalanine hydroxylase apoenzyme (PAH), but other causes may include a deficiency of dihydropteridine reductase (DHPR) or reduced production of biopterin (BH 4 ). (nih.gov)
- The second, dihydropteridine reductase (DHPR, PDB entry 1dhr ), adds a few hydrogen atoms and the cofactor is ready to go for the next reaction. (rcsb.org)
Deficiency6
- Dihydropteridine reductase deficiency (DHPRD) is a genetic disorder affecting the tetrahydrobiopterin (BH4) synthesis pathway, inherited in the autosomal recessive pattern. (wikipedia.org)
- Lack of sepiapterin reductase activity, an autosomal recessive variant of BH(4) deficiency presenting without HPA, was diagnosed in patients with seven different mutant alleles in the SPR gene in exons 2 or 3 or in intron 2. (qxmd.com)
- All these five genetic conditions can be identified by newborn screening procedures due to elevated blood levels of Phe (with the sole exception of sepiapterin reductase deficiency). (thieme-connect.de)
- [ 2 ] It was also shown that, in BH4 deficiency, dihydrofolate reductase (DHFR) plays a key role in regulating the ratio of BH4 to BH2 and eNOS coupling. (medscape.com)
- Although nearly all cases (98 to 99%) of PKU result from phenylalanine hydroxylase deficiency, phenylalanine can also accumulate if BH4 is not synthesized because of deficiencies of dihydrobiopterin synthase or not regenerated because of deficiencies of dihydropteridine reductase. (merckmanuals.com)
- Unlike other disorders of BH4 synthesis, patients with sepiapterin reductase (SR) deficiency do not present with hyperphenylalaninemia and are thus not detected by routine newborn screening. (preventiongenetics.com)
Sepiapterin reductase4
- Mutations in the BH4-metabolizing genes GTP cyclohydrolase I, 6-pyruvoyl-tetrahydropterin synthase, sepiapterin reductase, carbinolamine-4a-dehydratase, and dihydropteridine reductase. (qxmd.com)
- Finally, the enzyme sepiapterin reductase (SR, PDB entry 1sep ) cleans up the portion of the sugar that is left to form the final cofactor. (rcsb.org)
- A recent structure (PDB entry 4j7u ), revealed that the drugs bind to sepiapterin reductase, blocking its action and ultimately blocking the production of neurotransmitters. (rcsb.org)
- 1sep: G. Auerbach, A. Herrmann, M. Gutlich, M. Fischer, U. Jacob, A. Bacher & R. Huber (1997) The 1.25 A crystal structure of sepiapterin reductase reveals its binding mode to pterins and brain neurotransmitters. (rcsb.org)
Dihydrofolate3
- dihydrofolate reductase [Source:HGNC Sym. (gsea-msigdb.org)
- Bacteria cannot directly use the folic acid in their growth environment, but use the p-aminobenzoic acid (PABA), dihydropteridine and glutamic acid in the environment to synthesize dihydrofolate under the catalysis of dihydrofolate synthase in the bacteria. (ballyabio.com)
- Dihydrofolate forms tetrahydrofolate under the action of dihydrofolate reductase. (ballyabio.com)
Ferredoxin reductase1
- ferredoxin reductase [Source:HGNC Symbol. (gsea-msigdb.org)
Tetrahydrobiopterin1
- however, other causes are deficiencies in dihydropteridine reductase or in the biosynthesis of tetrahydrobiopterin. (blogspot.com)
1.341
- The 6,7-dihydropteridine must be enzymically reduced back to tetrahydropteridine, by EC 1.5.1.34 , 6,7-dihydropteridine reductase, before it slowly rearranges into the more stable but inactive compound 7,8-dihydropteridine. (enzyme-database.org)
Nitrite1
- Nitrite reductases. (lookformedical.com)
Dehydratase1
- The 4a-hydroxytetrahydropteridine formed can dehydrate to 6,7-dihydropteridine, both spontaneously and by the action of EC 4.2.1.96 , 4a-hydroxytetrahydrobiopterin dehydratase. (enzyme-database.org)
QUINOID DIHYDROPT5
- The QDPR gene provides instructions for making an enzyme called quinoid dihydropteridine reductase. (medlineplus.gov)
- Quinoid dihydropteridine reductase is one of two enzymes that help recycle tetrahydrobiopterin in the body. (medlineplus.gov)
- Most QDPR gene mutations change single amino acids in quinoid dihydropteridine reductase, although some mutations insert small amounts of DNA into the QDPR gene or disrupt the way the gene's instructions are used to make the enzyme. (medlineplus.gov)
- Changes in quinoid dihydropteridine reductase greatly reduce or eliminate the enzyme's activity. (medlineplus.gov)
- Additionally, a reduction in quinoid dihydropteridine reductase activity disrupts the production of certain neurotransmitters in the brain. (medlineplus.gov)
Synthase3
- Thony B, Blau N. Mutations in the BH4-metabolizing genes GTP cyclohydrolase I, 6-pyruvoyl-tetrahydropterin synthase, sepiapterin reductase, carbinolamine-4a-dehydratase, and dihydropteridine reductase. (medlineplus.gov)
- Nare, B., Hardy, L. and Beverley, S.M. The roles of pteridine reductase 1 and dihydrofolate reductase-thymidylate synthase in pteridine metabolism in the protozoan parasite Leishmania major . (enzyme-database.org)
- Unlike human and mammalian cells, bacteria that are sensitive to sulfonamides cannot directly use folic acid in the surrounding environment, but can only use p-aminobenzoic acid (PABA) and dihydropteridine to be catalyzed by dihydrofolate synthase in bacteria Dihydrofolate is synthesized, and then tetrahydrofolate is formed by the action of dihydrofolate reductase. (ballyabio.com)
Oxidoreductase1
- Molybdopterin oxidoreductase, Molydopterin dinucleotide binding domain, Respiratory nitrate reductase alpha N-terminal [Interproscan]. (ntu.edu.sg)
NADH3
- From NCBI Gene: This gene encodes the enzyme dihydropteridine reductase, which catalyzes the NADH-mediated reduction of quinonoid dihydrobiopterin. (nih.gov)
- The rat liver dihydropteridine reductase was purified over 960 fold over the original supernatant and Km's for the two substrates NADH and quinonoid dimethyldihydropterin (qDMPH2) were 1.7 x 10¯5M and 2.1 x 10¯5 respectively. (aston.ac.uk)
- Human brain dihidropteridine reductase was purified 20 fold over the orignal supernatant and Km's for NADH and qDMPH2 were 1.9 x 10¯5M and 2.9 x 10‾5M respectively. (aston.ac.uk)
Enzyme2
- In vitro experiments using human brain dihydropteridine reductase showed lead to significantly inhibit enzyme activity in an irreversible manner. (aston.ac.uk)
- Dihydropteridine reductase activity in crude tissue preparations was increased in rat liver as a consequence of oestrogen dosing, whilst purified rat liver enzyme was strongly inhibited by oestrone, oestradiol and their catechol derivatives. (aston.ac.uk)
NADPH1
- It also differs from EC 1.5.1.3 (dihydrofolate reductase) in being specific for the Si -face of NADPH. (enzyme-database.org)
Activity3
- The effect of lead on d1hydropteridrne reductase activity in vivo was investigated using rat brains from animals subjected to a leaded water regime from conception. (aston.ac.uk)
- Human brain dihydropteridine reductase activity was elevated in temporal lobe samples from patients suffering from senile dementia of the Alzheimer type as compared to age matched controls, but this elevation was not significant. (aston.ac.uk)
- Dihydropteridine reductase activity was measured in several human brain regions. (aston.ac.uk)
HUMAN1
- Dihydropteridine reductase has been purified from rat liver and human brain tissue samples by affinity chromatography using sodium 1,2-naphthoquinone-4-sulphonate as the ligand. (aston.ac.uk)
Beta1
- 4Fe-4S dicluster domain, Respiratory nitrate reductase beta C-terminal [Interproscan]. (ntu.edu.sg)