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Biomedical subjects

L Wilson

Publications and source records attributed to L Wilson.

At least 379 records · Page 21Linked to original sources
PubMed1982

Alterations in reproductive tissue prostaglandins E and F, 6-keto-prostaglandin F1 alpha and thromboxane B2 with gestational age in the rat.

Prostaglandins (PGs) are thought to have an important function in the initiation and/or propagation of parturition. To define the relationship of individual PGs to one another and compare their alterations with gestational age, PGF, PGE, 6-keto-PGF1 alpha (6KF) and thromboxane B2 (TxB2) were measured in uterine and placental tissue and uterine venous plasma of rats at Days 15, 18, 19, 20, and 21 of pregnancy and at delivery (Day 21 1/2). In addition, concomitant measurements of peripheral plasma estradiol (E2), estrone (E1) and progesterone (P) and pituitary oxytocin (OT) content, putative regulators and/or modulators of PG metabolism, were determined. Significant enhancements (P less than 0.05) in uterine 6KF, TxB2, PGF and PGE concentrations (ng/mg DNA) were detected by Day 20 compared to Day 15 of pregnancy and further dramatic increases were found on Day 21 and at delivery. Although uterine 6KF was present in the highest concentrations, PGF showed the greatest increment from Day 15 to delivery. No alterations in uterine venous plasma PGE or PGF concentration were found with gestational age but 6KF and TxB2 showed significant increases at delivery. The placental concentrations of PGs were approximately 1/50 of uterine tissue. Placental PGE and PGF concentrations (ng/mg DNA) increased only slightly at delivery but the augmentation in 6KF and TxB2 levels were of greater magnitude. Significant increases in E2 and E1 with reciprocal decreases in P occurred on Day 21 of pregnancy. In contrast, pituitary OT content showed no alterations at any of the days examined. These results are consonant with the hypothesis that uterine PGs have an important function in parturition and uterine-placental physiology, and suggest that an increasing estrogen/P ratio at the end of pregnancy is related to enhanced uterine PG levels.

6-Ketoprostaglandin F1 alpha↗
PubMed1982

In vivo biomicroscopy and photography of meibomian glands in a rabbit model of meibomian gland dysfunction.

The usefulness of transillumination and biomicroscopy of the lid margin in assessing meibomian gland dysfunction was studied in a rabbit model. Transillumination of rabbit lids treated with topical epinephrine for 2 to 3 months revealed plugging of the meibomian gland orifice. Plugging appeared to be correlated histopathologically with increased thickness and hyperkeratinization of the ductal epithelium at the orifice. Continued treatment resulted in microcystic changes within the duct, which were not easily discernible by routine examination without the aid of a transilluminator. Cystic changes were correlated with dilation of the duct by retained desquamated cornified cells. Biomicroscopy proved valuable in identifying and documenting early lesions associated with epinephrine-induced meibomian gland dysfunction.

Animals↗
PubMed1981

Microtubule treadmills--possible molecular machinery.

Microtubule polymerization in vitro is the summation of different reactions occurring at each end of the polymer. In steady-state conditions in vitro, net tubulin addition on the microtubule occurs at one end of the polymer, and net tubulin loss occurs at the opposite end. Thus, a unidirectional flux of tubulin from one end of the microtubule to the other, or "treadmilling', can occur. The opposite end assembly--disassembly behaviour of microtubules, if it occurs within cells, could be fundamentally linked to the functions of microtubules, as, for example, in the translocation of chromosomes during mitosis.

Actins↗
PubMed1981

Changes in the circular dichroic spectrum of colchicine associated with its binding to tubulin.

Circular dichroism has been used to study the interaction of colchicine with the tubulin alpha beta dimer at 26 degrees C. Tubulin purified from bovine brain microtubule protein exhibits negligible circular dichroism at wavelengths above 310 nm. Free colchicine exhibits a negative circular dichroic band at 340 nm characterized by an extremum in molar ellipticity [theta] of -3.35 (+/- 0.27) x 10(4) deg.cm2/dmol. This negative band either vanished or was greatly reduced, i.e., [theta] = 0 (+/- 0.57) x 10(4) deg.cm2/dmol, when colchicine was bound to tubulin. This was demonstrated by circular dichroic studies on stable [3H]colchicine-tubulin complexes which were separated from all unbound colchicine by means of gel filtration. Also, tubulin was titrated with colchicine, and at low colchicine concentrations, the observed ellipticity at 340 nm could be extrapolated to zero at 0 M colchicine; saturation occurred at a molar ratio of colchicine to tubulin of about 1:1. The association constant characterizing the drug-protein interaction was estimated to be about 0.9 micro M-1. As controls, three other acidic proteins were studied at a molar ratio of colchicine to protein of 2:1, and their presence had no effect on the circular dichroic properties of colchicine. These results are consistent with the idea that a conformational change in colchicine accompanies its binding to tubulin. The spectrum of the complex between 250 and 300 nm was quite similar to that expected from simple additivity of the spectra of drug and protein except between 255 and 265 nm. The technique described herein should be applicable to other protein-drug systems.

Animals↗
PubMed1981

Heterologous synapses upon Purkinje cells in the cerebellum of the Reeler mutant mouse: an experimental light and electron microscopic study.

The projections of the spinal cord upon the cerebellum of normal and Reeler mutant mice were compared by light and electron microscopic methods after hemicordotomy. In both genotypes this afferent system projects to the cerebellar cortex and to the roof nuclei. In the Reeler, there is an additional projection among the Purkinje cells and interneurons of the central cerebellar mass. In both normal and Reeler cerebellar cortex this mossy fiber system terminates as large glomeruli. In Reeler the spinal projection also gives rise to a smaller terminal which is distributed both to the cortex and the central cerebellar mass. In both genotypes the dendrites of granule cells and the somata and dendrites of Golgi cells are synaptic targets of the glomeruli of the cortical projection. In Reeler both the glomeruli and smaller terminals also form heterologous synaptic contacts with dendrite spines of heterotopic intracortical and subcortical Purkinje cells. In both genotypes the synapses are exclusively type I. A second class of heterologous synapse, a type I junction between axons of Golgi cells and Purkinje cell spines, is also recognized in electron micrographs. The present study is the first unequivocal demonstration by experimental hodologic method of heterologous synaptic junctions in the mammalian central nervous system. The existence of such junctions in the cytoarchitectonically anomalous cerebellum of this mutant emphasizes the critical role played by the cellular environment in shaping neural circuits in the developing nervous system.

Afferent Pathways↗
PubMed1981

Taxol induces microtubule assembly at low temperature.

Dissociated bovine brain microtubule protein has been shown to reassemble at 0 degrees C in the presence of the drug taxol. Tubulin polymerization was monitored both by electron microscopy of the polymeric structures and by incorporation of tritiated GTP into filterable polymeric structures. Most of the labeled guanine nucleotide uptake into tubulin polymeric structures occurred in the first 30 minutes of incubation with the drug. The initial polymerization event results in the formation of protofilamentous tubulin ribbons. The first microtubules were noted after 1 hour of incubation with the drug. After 20 hours of incubation at 0 degrees C with taxol, the bulk of the polymerized tubulin appeared to be in the form of microtubules. Cold-stable tubulin rings with a mean diameter of 34 nm were present in the reaction mixture before the addition of taxol and throughout the 20-hour incubation. Most of the rings were apparently not involved in the taxol-induced microtubule assembly. The results are consistent with a model whereby taxol induces an initial formation of protofilamentous ribbon structures, mostly from free tubulin dimers, and a slower subsequent folding of the ribbon structures into microtubules.

Alkaloids↗
PubMed1981

Absence of activated murine leukaemia virus in x-irradiated CBA/H-T6crc mice.

CBA/H-T6Crc mice, a substrain that does not normally express demonstrable levels of murine leukaemia virus (MuLV) and has a low natural incidence of leukaemia, were examined for evidence of virus activation at various times following X-irradiation. Although X-irradiation caused a high incidence of leukaemia, no ecotropic, xenotropic or recombinant MuLV was detected by in vitro co-cultivation of bone marrow, spleen and thymus cells from pre-leukaemic and leukaemic animals with selectively permissive cell lines followed by indirect immunofluorescence for MuLV group-specific (gs) antigen. These results, therefore, are not consistent with the hypothesis that endogenous viruses are the universal aetiological agents of leukaemia.

Animals↗
PubMed1981

Ultrastructural studies on the peritoneum with special reference to chronic ambulatory peritoneal dialysis.

Specimens of peritoneum from normal rat, mouse, man, uraemic patients and patients on chronic ambulatory peritoneal dialysis (C.A.P.D.) were examined by en face silver stained preparations and by electron microscopy. The ultrastructural features of the mesothelium and subjacent tissues in normal man, animal and uraemic patients were closely similar. Cellular degeneration and oedema were observed in the mesothelium of patients on C.A.P.D.

Animals↗
PubMed1981

Incidence of sensory integrative dysfunction among children with orofacial cleft.

Occupational therapists working with children with clefts observed that those children demonstrated subtle developmental delays, including learning, language, and behavioral problems that appeared related to sensory integrative dysfunction as identified by Ayres in children with learning disabilities. This study explored the possible existence of sensory integrative dysfunction in children with clefts when compared to normative data published by Ayres. The Southern California Sensory Integration Tests and the Southern California Postrotary Nystagmus Tests were administered to 70 four- to nine-year old children with clefts, who had been selected from four different hospital settings. Comparisons of the mean subtest scores of the sample children and the norms showed that significant levels (p less than .05) of difference existed. The subjects with clefts exhibited dysfunction related to vestibular and tactile processing and bilateral integration. No relationship was found between sensory integrative dysfunction and the child's cleft type, sex, or hospital setting.

Child↗
PubMed1981

Selective compounds derived from marine organisms: effects on cell division in fertilized sea urchin eggs.

An investigation of the pharmacological selectivity of the fertilized sea urchin egg assay was undertaken with the view that this echinoderm may serve as a useful model for detecting new compounds that inhibit cell division and also may yield substantive information on biochemical events that may be sensitive to drug action. One hundred and thirty purified marine natural products were tested as well as 14 known antineoplastic agents. Nine active marine cytotoxins were identified and, based on in vitro studies of microtubule assembly, five compounds inhibited tubulin polymerization. Of the 14 antineoplastic agents tested thus far, the transcriptional inhibitor daunomycin has proven active as well as the microtubule assembly inhibitors Colcemid, podophyllotoxin, vinblastine, and vincristine.

Animals↗