Proceedings of the 4th International DNA Fingerprinting Conference. Melbourne, Australia, December 2-7, 1996.
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Animals↗
Biomedical subjects
C A May
Publications and source records attributed to C A May.
Description and function of the ciliary nerves--some historical remarks on choroidal innervation.
The earliest accounts of the eye recognized its main function as providing vision, but the mechanism of how the eye functioned remained obscure for many centuries. The aim of the following work is to outline these changes in the understanding of a particular structure and function of the human body, namely, the ciliary nerves supplying the uveoscleral part of the eye. In the extensive study on the history of ophthalmology by Hirschberg (published between 1899 and 1918), the ciliary nerves and choroidal innervation are only sparsely mentioned.
Choroid↗
Choroidal ganglion cell plexus and retinal vasculature in monkeys with laser-induced glaucoma.
The choroid of primates possesses an elaborate nitrergic nerve fiber plexus containing a great number of ganglion cells. Postganglionic nerve fibers innervate mainly the choroidal vasculature. In addition, the choroid contains an elastic muscular system closely associated to the vasculature. The goal of the present investigation was to analyze how sustained IOP elevation would affect the choroidal vasculature with its specialized innervation and the adjacent retina. For this purpose the posterior eye segment of 15 rhesus monkeys which after laser coagulation of the trabecular meshwork developed elevated IOP up to 4 years were studied using immunohistochemical and histochemical methods, and scanning electron microscopy of corrosion casts. The most striking finding was a significant reduction of choroidal thickness and loss of choroidal ganglion cells and nerve fibers, especially in the central portion of the choroid. Corrosion casts of the choroidal vasculature showed a slight decrease in capillary density and a decrease in length of the arterioles in glaucomatous eyes. Whole mount preparations of the retina stained for NADPH diaphorase revealed a significant reduction in positively stained amacrine cells, reduction in diameter of arterioles and changes in the staining pattern of the retinal vasculature, particularly in the perimacular region.
Animals↗
Quantitative and morphological changes of the choroid vasculature in RCS rats and their congenic controls.
In Royal College of Surgeons (RCS) rats the outer retina degenerates owing to a phagocytic defect of the retinal pigmented epithelium (RPE). To analyse whether the choriocapillaris also undergoes degenerative changes, corrosion casts of choroidal vessels of ten RCS rats and 12 age-matched controls of different age groups were investigated by scanning electron microscopy. The pattern of the ciliary arteries was analysed qualitatively and the areas covered by capillaries in the different quadrants and regions of the choroid were evaluated quantitatively. In both RCS rats and their congenic controls the choroid was supplied by only three ciliary arteries. A separate artery supplying the upper quadrant in other rat strains was lacking. The quantitative evaluation revealed that in controls the capillary density decreased from the central to the peripheral regions. In addition there were slightly fewer capillaries in the upper temporal quadrant compared to other quadrants. In RCS rats older than 6 months, all parts of the choroid displayed a decrease in the number of capillaries of about 10-15% compared to the controls. Most prominent loss of capillaries was found in the upper temporal quadrant. Electron-microscopical investigation of the upper temporal quadrant showed that loss of choriocapillaris was directly correlated with degeneration of the adjacent retinal pigmented epithelium (RPE).
Animals↗
Minisatellite diversity supports a recent African origin for modern humans.
In a study of human diversity at a highly variable locus, we have mapped the internal structures of tandem-repetitive alleles from different populations at the minisatellite MS205 (D16S309). The results give an unusually detailed view of the different allelic structures represented on modern human chromosomes, and of the ancestral relationships between them. There was a clear difference in allelic diversity between African and non-African populations. A restricted set of allele families was found in non-African populations, and formed a subset of the much greater diversity seen on African chromosomes. The data strongly support a recent African origin for modern human diversity at this locus.
Africa↗
Mutation rate heterogeneity and the generation of allele diversity at the human minisatellite MS205 (D16S309).
Many tandemly repeated minisatellite loci display extreme levels of length variation as a consequence of high rates of spontaneous germline mutation altering repeat copy number. Direct screening for new allele lengths by small-pool PCR has shown that instability at the human minisatellite locus MS205 (D16S309) is largely germline specific and usually results in the gain or loss of just a few repeat units. Structural analysis of the order of variant repeats has shown that these events occur preferentially at one end of the tandem array and can result in complex rearrangements including the inter-allelic transfer of repeat units. In contrast, putative mutants recovered from somatic DNA occur at a substantially lower rate and are simple and non-polar in nature. Germline mutation rates vary considerably between alleles, consistent with regulation occurring in cis. Although examination of DNA sequence polymorphisms immediately flanking the minisatellite reveals no definitive associations with germline mutation rate variation, differences in rate may be paralleled by changes in mutation spectrum. These findings help to explain the diversity of MS205 allele structures in modern humans and suggest a common mutation pathway with some other minisatellites.
Alleles↗
Presence of a contractile cell network in the human choroid.
Immunohistochemical staining of choroidal whole mounts as well as serial tangential sections and electron-microscopic investigation of 21 human donor eyes revealed a network of nonvascular alpha-smooth-muscle-actin-positive cells (NVSMC) in the entire choroid most densely arranged in the posterior part of the suprachoroid of the submacular region. Ultrastructurally these cells present the typical structure of myofibroblasts. Double labeling with desmin and smooth muscle myosin showed a positive reaction only in few of these cells. Posteriorly the NVSMC net reaches the optic nerve, anteriorly it ends in the region of the vortex veins but does not continue into the ciliary muscle. In places, intimate contact between the contractile cells and the elastic fiber network of the choroidal stroma and the perivascular sheaths is seen. The elastic net of the choroid is firmly connected with the posterior elastic tendons of the ciliary muscle. In the course of accommodation, the ciliary muscle pulls this net foreward presumably influencing position and diameter of the choroidal vessels. We assume that the network of NVSMC of the choroid counteracts the ciliary body movements during accommodation, thus guaranteeing the three-dimensional architecture of the choroid and the position of the retina, particularly in the macular region.
Actins↗
alpha B-crystallin in the primate ciliary muscle and trabecular meshwork.
The presence of alpha B-crystallin, a protein with heat-shock protein-like properties, has been demonstrated in ciliary muscle and trabecular meshwork derived from human and monkey eyes using immunohistochemical and polymerase chain reaction methods. Both frozen sections and cultured cells have been analyzed. In the ciliary muscle, alpha B-crystallin staining is localized in the region of the dense bands, in the cytoplasm of the muscle cells and in the Schwann cells of the nerves supplying the muscle. In the trabecular meshwork, two cell types could be distinguished on the basis of alpha B-crystallin occurrence. Whereas the trabecular cells covering the lamellae were virtually devoid of the protein, the subendothelial or cribriform cells contained relatively large amounts in parallel with a higher alpha B-crystallin mRNA level.
Adult↗
Mutation processes at human minisatellites.
Minisatellites provide one of the most experimentally tractable systems for studying tandem repeat instability in man. Analysis of mutation processes has been greatly aided by the development of single molecule methods for recovering de novo mutants, and of techniques for exploring allele structure in detail. Application of these approaches to man has shown that minisatellites do not primarily mutate by processes such as replication slippage and unequal crossover intrinsic to the tandem repeat array. Instead, germline repeat instability is largely regulated by cis-acting elements near the array and involves unexpectedly complex processes of gene conversion, of potential relevance to the biology of meiosis. These processes can be explored both in humans and, in principle, in transgenic mouse models of human repeat instability.
Alleles↗
Charomid cloning vectors meet the pedipalpal chelae: single-locus minisatellite DNA probes for paternity assignment in the harlequin beetle-riding pseudoscorpion.
We describe the first application of the charomid-cloning method for developing single-locus minisatellite DNA probes in a terrestrial arthropod. From a genomic library of the neotropical pseudoscorpion, Cordylochernes scorpioides, we have isolated two probes with heterozygosities exceeding 95%. These probes yielded single-locus patterns after only low stringency washing and in the absence of genomic competitor DNA. Analysis of three pedigrees indicated germline stability and showed no evidence of linkage between the loci. Patterns of allelic transmission generally conformed closely to Mendelian expectations but large offspring numbers did enable detection of one example of significant bias in allele inheritance. Two test cases are presented to illustrate the clarity and power with which these probes can establish paternity: (i) a female mated to three unrelated males, and (ii) a female mated to two of her brothers. In both cases, a single probe could be used to assign the paternity of all offspring.
Animals↗
Nitric oxide inhibits resting sphincter of Oddi activity.
The sphincter of Oddi has basal myogenic phasic activity that is modulated by neural and hormonal pathways. Stimulatory innervation to this organ is cholinergic, whereas the inhibitory pathways are unknown. Nitric oxide (NO), generated from L-arginine, relaxes gastrointestinal smooth muscle in vitro. We, therefore, hypothesized that resting sphincter of Oddi and duodenal motilities are regulated by a NO-mediated inhibitory pathway. In 23 anesthetized prairie dogs, systemic blood pressure and sphincter of Oddi and duodenal motilities were monitored during systemic infusion of N omega-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase. L-NAME was infused alone and simultaneously with excess D- and L-arginine. L-NAME alone and L-NAME with D-arginine produced hypertension and increased sphincter of Oddi and duodenal motilities. L-arginine blocked these increases, suggesting that baseline sphincter of Oddi and duodenal motility regulation involves the generation of NO from L-arginine. We conclude that baseline sphincter of Oddi phasic activity is regulated by cholinergic stimulatory and NO-mediated inhibitory neural pathways.
Amino Acid Oxidoreductases↗
DNA fingerprinting by specific priming of concatenated oligonucleotides.
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Animals↗
The effect of calcium on gallbladder absorption.
The absorption of water and electrolytes is an important physiologic function of the gallbladder which is altered during gallstone formation. Extracellular calcium and calcium channel antagonists are known to affect intestinal absorption, yet their effect on gallbladder absorption is less well defined. We, therefore, tested the hypothesis that changes in extracellular calcium or in calcium channels would alter gallbladder absorption. New Zealand white rabbit gallbladders were removed, filled with a modified Krebs buffer (Ca2+ = 0.7 mM), and suspended in an oxygenated bath of the same buffer. Water absorption was determined gravimetrically by obtaining serial gallbladder weights at 10-min intervals. After a 40-min control period, the serosal bathing solution was changed to one of four experimental solutions (n = 6 for each group): Ca2+ = 0.25, 0.7, or 1.2 mM or Ca2+ = 0.7 mM plus 0.1 mM verapamil. Absorption was determined during an 80-min experimental period with results expressed as the percentage change in gallbladder absorption compared to that of the control period. The 0.25, 0.7, and 1.2 mM Ca2+ groups did not show a significant change in absorption rate from their respective control rates. However, the verapamil group did demonstrate a significant (P less than 0.05) decrease in absorption rate of -69 +/- 8% by the end of the experimental period. These data demonstrate that verapamil inhibits gallbladder absorption while changes in serosal calcium concentration have no effect. We conclude that calcium channels and intracellular calcium may play an important role in modulating gallbladder absorption.
Absorption↗
Treatment of adrenocortical carcinoma: a case report and review of the literature.
A case report of adrenocortical carcinoma is presented, and its natural history and treatment are discussed. Adrenocortical carcinoma is a rare malignant disease. The mean survival time for untreated patients is less than three months. The tumor is classified as functioning or nonfunctioning depending on biochemical and clinical evidence of steroid overproduction. Surgical resection of the tumor is the primary treatment. Chemotherapy is indicated for antitumor and antihormonal effects. Mitotane is a direct adrenolytic, and is the only drug currently available that has extended survival in patients with this disease. Its clinical usefulness is limited by its gastrointestinal and neurological toxicity. Aminoglutethimide inhibits steroid synthesis by blocking the conversion of cholesterol to pregnenolone. It has no antitumor effect in adrenocortical carcinoma, but is effective in relieving the signs and symptoms of excessive hormone production in functioning tumors. Both mitotane and aminoglutethimide have complex mechanisms of action. Their combined use in the treatment of adrenocortical carcinoma requires a complete understanding of their individual actions and awareness of the potential for additive effects, both therapeutic and toxic.
Adrenal Cortex Neoplasms↗
Methyldopa does not alter the disposition of digoxin.
To investigate whether methyldopa alters digoxin disposition, eight healthy subjects received methyldopa titrated to 250 mg t.i.d. or placebo in a double-blind, cross-over manner for 16 consecutive days, with 0.25 mg intravenous digoxin coadministered on day 5 and 0.25 mg oral digoxin on days 9 to 16. Digoxin concentrations in plasma and urine were measured by RIA. Although assay sensitivity did not allow an adequate assessment of serum AUC(0-infinity) after intravenous administration, mean digoxin AUC(0-24) was 10.2 +/- 3.5 and 10.0 +/- 1.8 ng/ml X hr with placebo and methyldopa, respectively (P greater than 0.05). Mean urinary excretion after digoxin with or without methyldopa treatment was 0.204 +/- 0.34 and 0.197 +/- 0.38 mg, respectively. The mean steady-state serum concentrations of oral digoxin (AUC(0-24)/zeta) with and without methyldopa were 0.65 +/- 0.2 and 0.62 +/- 0.3 ng/ml, respectively. These data revealed no significant differences (P greater than 0.05) for various parameters with power of greater than 0.8 to detect meaningful differences of approximately 30 per cent. Thus, methyldopa did not alter digoxin disposition in healthy subjects, and a pharmacokinetic interaction in patients is unlikely.
Administration, Oral↗
Alpha-B-crystallin expression in tissues derived from different species in different age groups.
alphaB-Crystallin is constitutively expressed in a variety of tissues including the nervous system, the eye, heart and striated muscles and the kidney. The functional significance of the protein in the different cell populations is not yet known. Experimental data indicate that mechanical stress to the cells might play a role but that there is also a close correlation with markers of oxidative activity. Increased expression of alphaB-crystallin is seen in a number of age-related degenerative diseases. Whether aging per se induces expression of the protein has not been investigated yet. In this study tissue samples of the anterior eye segment, optic nerve, heart muscle and thyroid gland from mouse, rat, pig, cow and human donors of different age groups were investigated with immunohistochemical methods. alphaB-Crystallin levels in heart muscle and optic nerve samples from different species and different age groups were investigated using protein immunoblotting (dot blot) and the mRNA levels using semiquantitative PCR methods. The results showed that neither in heart muscle known to show constitutively high amounts of the protein nor in nonlenticular eye tissues with variations in staining intensity of different cell populations or in glandular cells studied for the first time, there were significant age-related staining differences. Dot blot methods as a quantitative evaluation method gave similar results. There were, however, species differences. In the eye these differences could be due to functional differences related to the development of a fovea centralis and an accommodative system in primates. In addition, in all mouse tissues there was less protein expression than in the other species. Differences in the absolute life span might be a factor involved in alphaB-crystallin expression. In summary the findings show that an increase in alphaB-crystallin with age may occur but is not a general phenomenon in tissues constitutively expressing this protein.
Adult↗
Vascular and glial changes in the retrolaminar optic nerve in glaucomatous monkey eyes.
Vascular and glial changes of the retrolaminar optic nerve were studied in monkey eyes with increased intraocular pressure (IOP) from 1 to 4 years and with different stages of optic nerve atrophy. In histological cross-sections of retrolaminar optic nerves of 11 rhesus and 6 cynomolgus monkeys the entire area, number of axons and vessels and area of pial septa were quantitated and three different kinds of nerve degeneration classified. Ultrathin sections of these different stages were performed and the number of open and occluded vessels was determined. In addition, in cynomolgus monkey optic nerves immunohistochemical staining for alphaB-crystallin, glial fibrillary acidic protein (GFAP) and vimentin was performed. Even in animals with the same duration of glaucoma and comparable mean IOP values the axon degeneration varied considerably. Independently of axon loss the number of capillaries in the rhesus monkeys remained constant, whereas there was a slight decrease in the cynomolgus monkeys. Some of the vessels, especially in the most severely damaged regions, were occluded. The density of glial cells increased whereas the total number remained nearly constant. In control sections all astrocytes stained for GFAP and alphaB-crystallin. In the glaucomatous optic nerves the density of alphaB-crystallin- and GFAP-positive cells was significantly increased. The vascular reaction in the retrolaminar glaucomatous optic nerves differs from that described in the prelaminar region. We assume that in the postlaminar region in areas with diminished nutritional needs vessels occlude and finally degenerate.
Animals↗
Alpha B-crystallin in the mammalian inner ear.
To study the distribution of alpha B-crystallin, formalin-fixed preparations of the inner ear of the rat, cynomolgus monkey, rhesus monkey and human were stained immunohistochemically for alpha B-crystallin. In all cochleae investigated, intense staining for alpha B-crystallin was found in the inner and outer pillars as well as in the cells of Hensen and Claudius. In the primate inner ear, alpha B-crystallin was also present in the polygonal epithelial cells of Reissner's membrane, the interdental cells and some fibrocytes of the spiral limbus, epithelial cells of the outer spiral sulcus and the Schwann cells of the 8th nerve. In the primate stria vascularis, alpha B-crystallin was mainly seen in the basal cell layer and the adjacent cells of the connective tissue layer. alpha B-crystallin was found to be present in a large variety of cells in the inner ear surrounding the scala media.
Aged↗