Identifying homologous anatomical landmarks on reconstructed magnetic resonance images of the human cerebral cortical surface.
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Guided by a review of the anatomical literature, 36 sulci on the human cerebral cortical surface were designated as homologous. These sulci were assessed for visibility on 3-dimensional images reconstructed from magnetic resonance imaging scans of the brains of 20 normal volunteers by 2 independent observers. Those sulci that were found to be reproducibly identifiable were used to define 24 landmarks around the cortical surface. The interobserver and intraobserver variabilities of measurement of the 24 landmarks were calculated. These reliably reproducible landmarks can be used for detailed morphometric analysis, and may prove helpful in the analysis of suspected cerebral cortical structured abnormalities in patients with such conditions as epilepsy. (+info)
Hyperpolarization-activated current I(h) in nucleus of solitary tract neurons: regional difference in serotonergic modulation.
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The nucleus of solitary tract (NTS) contains diverse neural circuits responsible for basic vital functions. We examined the effect of serotonin (5-HT) on hyperpolarization-activated current (I(h)) in neurons acutely isolated from caudal, medial and rostral parts of the NTS. Caudal and medial NTS neurons showed a large amplitude of I(h) compared with rostral neurons. In these neurons, perfusion with 5-HT potentiated Ih amplitude in a concentration-dependent manner. The effect of 5-HT was blocked by NAN-190, a 5-HT1A receptor antagonist. Thus, 5-HT1A receptors may regulate I(h) channel activity in caudal and medial NTS neurons. (+info)
Regional distribution of Na,K-ATPase activity in porcine lens epithelium.
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PURPOSE: It has been established that Na,K-ATPase activity is higher in lens epithelium than fibers. However, others have suggested the Na,K-ATPase enzyme may be inactive or absent in the central 10% of the epithelium. Studies were conducted to measure and compare Na,K-ATPase specific activity and to examine Na,K-ATPase protein expression in the anterior and equatorial regions of porcine lens epithelium. METHODS: Na,K-ATPase activity was determined by measuring the ouabain-sensitive rate of adenosine triphosphate (ATP) hydrolysis. Western blot analysis was used to detect Na,K-ATPase catalytic subunit (alpha) and glycoprotein subunit (beta) protein as well as beta-actin which was used as a loading control. RESULTS: Na,K-ATPase specific activity was more than two times higher in the equatorial epithelium than the anterior 50% of the epithelium. However, the abundance of Na,K-ATPase alpha1 isoform protein was similar in the two regions. Neither the alpha2 nor alpha3 Na,K-ATPase isoform could be detected in the anterior or equatorial epithelium, but Na,K-ATPase beta1 protein was detected in both regions. In contrast to the observed regional difference in Na,K-ATPase activity, the activity of a different P-type ATPase, plasma membrane Ca-ATPase (PMCA), was not significantly different in the anterior and central epithelium. Western blot analysis indicated the presence of two PMCA isoforms, PMCA2, and PMCA4. CONCLUSIONS: Na,K-ATPase activity is significantly higher at the equatorial region of the epithelium compared with the anterior, even though the level of Na,K-ATPase protein is similar in the two regions. It is possible that nonuniform distribution of functional Na,K-ATPase activity contributes to the driving force for circulating solute movement through the lens fiber mass. (+info)
Regional variation in the structural response and geometrical properties of human ribs.
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By incorporating material and geometrical properties into a model of the human thorax one can develop an injury criterion that is a function of stress and strain of the material and not a function of the global response of the thorax. Previous research on the mechanical properties of ribs has focused on a limited set of specific ribs. For this study a total of 52 rib specimens were removed from four cadaver subjects. Variation in peak moment by thoracic region was significant (p < 0.01) with average values of 2, 2.9 and 3.9 N-m for the anterior, lateral and posterior regions respectively. Two geometrical properties, radius of gyration and distance from the neutral axis, showed significant variation by region (p < 0.0001) as well as by rib level (p = < 0.01, 0.05). The results of this study can be used to update current models of the human thorax to account for the variation in strength and geometrical properties throughout the rib cage. Accounting for the variation in rib properties by region will improve injury predictive measures and, therefore, the ability to design systems to prevent thoracic injury. (+info)
Selective anterograde tracing of the individual serotonergic and nonserotonergic components of the dorsal raphe nucleus projection to the vestibular nuclei.
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It is well known that the dorsal raphe nucleus (DRN) sends serotonergic and nonserotonergic projections to target regions in the brain stem and forebrain, including the vestibular nuclei. Although retrograde tracing studies have reported consistently that there are differences in the relative innervation of different target regions by serotonergic and nonserotonergic DRN neurons, the relative termination patterns of these two projections have not been compared using anterograde tracing methods. The object of the present investigation was to trace anterogradely the individual serotonergic and nonserotonergic components of the projection from DRN to the vestibular nuclei in rats. To trace nonserotonergic DRN projections, animals were pretreated with the serotonergic neurotoxin 5,7-dihydroxytryptamine (5,7-DHT), and then, after 7 days, the anterograde tracer biotinylated dextran amine (BDA) was iontophoretically injected into the DRN. In animals treated with 5,7-DHT, nonserotonergic BDA-labeled fibers were found to descend exclusively within the ventricular plexus and to terminate predominantly within the periventricular aspect of the vestibular nuclei. Serotonergic DRN projections were traced by injecting 5,7-DHT directly into DRN, and amino-cupric-silver staining was used to visualize the resulting pattern of terminal degeneration. Eighteen hours after microinjection of 5,7-DHT into the DRN, fine-caliber degenerating serotonergic terminals were found within the region of the medial vestibular nucleus (MVN) that borders the fourth ventricle, and a mixture of fine- and heavier-caliber degenerating serotonergic terminals was located further laterally within the vestibular nuclear complex. These findings indicate that fine-caliber projections from serotonergic and nonserotonergic DRN neurons primarily innervate the periventricular regions of MVN, whereas heavier-caliber projections from serotonergic DRN neurons innervate terminal fields located in more lateral regions of the vestibular nuclei. Thus, serotonergic and nonserotonergic DRN axons target distinct but partially overlapping terminal fields within the vestibular nuclear complex, raising the possibility that these two DRN projection systems are organized in a manner that permits regionally-specialized regulation of processing within the vestibular nuclei. (+info)
Clinically-relevant variations of the carotid arterial system.
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INTRODUCTION: Developmental anomalies in the origin and branching pattern of the external carotid artery are not common. The level of the bifurcation of the common carotid artery and also the variations in the origin/branching pattern of the external carotid artery are well known and documented. METHODS: The variations in the level of bifurcation of the common carotid artery and the branching pattern of the external carotid artery were studied on 95 cadavers (52 male and 43 female). The common, external and internal carotid arteries were dissected on both sides. The level of carotid bifurcation was determined by comparison with the cervical vertebrae. Branching patterns of the carotid arteries were examined. RESULTS: Apart from the textbook description of the arteries, we came across several interesting variations. The bifurcation level of the common carotid artery was determined to be 50 percent at the C3 level, 40 percent at the C4 level and ten percent at the C2 level on the right side, and 55 percent at the C3 level, 35 percent at the C4 level, one percent at the C5 level and nine percent at the C2 level on the left side. CONCLUSION: Anatomical knowledge of the origin, course, and branching pattern of the external carotid artery, as well as the level of bifurcation of the common carotid artery, will be useful to surgeons when ligating the vessels in the head and neck regions during surgery and to avoid unnecessary complications during carotid endarterectomy. (+info)
The relative position of the greater palatine foramen in dry Indian skulls.
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INTRODUCTION: We evaluated the relative position of the greater palatine foramen (GPF) for precise injection of local anaesthetics, for optimal pain control in maxillofacial and dental surgeries. METHODS: The study was conducted in 132 adult dried unsexed skulls of the west coast region of Southern India. All the skulls studied were normal with fully erupted third molars and free from any pathological changes. RESULTS: The statistical analysis indicated there was no significant difference in the measurement between the right and left sides with regard to the distance of GPF to the midline, GPF to the incisive fossa, GPF to the posterior border of the hard palate. The angle made by the line joining the GPF to the incisive foramen with the palatal midline (GIM angle) on two sides showed statistical significance. The mean angle on the left side was 21.2 +/- 4.2 degrees and 20.1 +/- 4.2 degrees on the right side. In 74.6 percent of skulls, the GPF was located opposite the third maxillary molars, whereas 24.2 percent showed the GPF between the second and third molars. In 0.4 percent of skulls, the GPF was opposite to the second molar and in 0.8 percent of skulls, the GPF was situated beyond the third molar. 46.2 percent of the GPF was directed forward and medially, whereas 41.3 percent was directed forward, and 12.5 percent as directed forward and laterally. CONCLUSION: The perpendicular distance of the GPF in Indian skulls was about 15 mm, the distance of GPF to incisive fossa was approximately 37 mm, and the GIM angle was 21 degrees. (+info)
Michael Servetus (1511-1553) and the discovery of pulmonary circulation.
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Michael Servetus was the first doctor ever to challenge and scientifically argue against the theories of Galen, which predominated for 14 centuries in medical schools worldwide. Even though he was relatively correct in scientific terms, Servetus was punished because of his boldness in challenging Galen's theories and was condemned to death by the Holy Inquisition. Yet, by publicly challenging Galen's and Hippocrates' predominant and unquestionable lessons on medicine for the first time, Servetus opened the door for other doctors to challenge and correct those theories and subsequently to bring about a new view of human anatomy and physiology. This article underlines the contribution of Servetus to the description of the pulmonary circulation. (+info)