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Biomedical subjects

A Whyte

Publications and source records attributed to A Whyte.

At least 109 records · Page 6Linked to original sources
PubMed1978

Saccharide distribution in human trophoblast demonstrated using fluorescein-labelled lectins.

The reaction of six Flourescein-conjugated lectins with human trophoblast and foetal limb are described. The trophoblast had marked membrane fluorescence after treatment with wheatgerm and Lotus tetragonolobus lectins. Concanavalin A reacted strongly with the trophoblastic cytoplasm but did not react with the nuclei. Most of the lectins had only weak reactions with foetal tissue, apart from the cartilage matrix which fluoresced strongly after treatment with several of the lectins. In addition, concanavalin A reacted with amylase-labile material, probably glycogen, in the skin epidermis and chondrocyte cytoplasm. Various substances were tested in order to determine the nature of the wheatgerm lectin receptor of trophoblast. Several secretory and binding proteins were found not to be responsible, and the identity of the receptor remains unknown.

Carbohydrate Metabolism↗
PubMed1978

Saccharide alterations in rat kidney associated with malignant transformation by injection of dimethylnitrosamine.

Renal tumours were induced in dietary-primed rats by injection of dimethylnitrosamine. Control and tumour tissue was excised at varying periods and maintained in short-term organ culture in the presence of 3H- or 14C-fucose. The plasma membranes were then isolated, and the isotopic profiles of normal kidney and renal tumour membrane proteins were established, using polyacrylamide-gel electrophoresis in dodecyl sulphate. Several fucose-containing glycoproteins of the plasma membranes were found to alter upon neoplastic transformation: 4 increased and 3 decreased. The probable identity of 2 of these proteins is indicated: alpha-foetoprotein is one of the glycoproteins which increased, whereas neutral endopeptidase decreased in the tumour membranes. Fluorescein-labelled lectin binding by the kidney tissue was also found to alter upon transformation. The most marked changes were an increase in sialic acid (neuraminidase-sensitive) and galactosamine (Ricinus communis agglutinin Type I) in the nuclei of some neoplastic cells and some hyperplastic-tubule cells.

Animals↗
PubMed1977

Variation in the volume of coated vesicles isoalted from human placenta.

Electron microscopic analysis of 500 negatively stained coated vesicles isolated from human placenta showed that they exist within limits in a continuous range of volumes with an unimodal distribution. Some vesicles were larger than the frequently quoted maximum size of these organelles (diameter 100nm). The ratio of hexagonal to pentagonal facets in the clathrin lattice of the vesicle wall appears to be variable. This feature may be important in morphogenesis since the mean volume of prolate vesicles is larger than that of spherical vesicles. Empty lattices had a mean volume smaller than that of lattices containing phospholipid bilayers.

Female↗
PubMed1977

Differeniated regions of human placental cell surface associated with exchange of materials between maternal and foetal blood: coated vesicles.

Coated vesicles may be an important component of the micropinocytic system of the human placenta. Regions of very dense reaction with glycocalyx stains are restricted to membranes within forming and fully formed coated vesicles. This is interpreted as evidence against permanently grouped specific binding sites having a role in the selective uptake of materials by micropinocytosis, and as support for theories of coated-vesicle formation which take into account the dynamic nature of membrane components. The pyroantimonate precipitation technique which was employed in an attempt to localize cations in placental tissue at term resulted in the deposition of electron-dense material in coated vesicles and basement membrane. Examination of the distribution of coated vesicles in placental tissue explants at 8--12 weeks of gestation revealed a restricted distribution of these organelles. Probably more than 89% of coated vesicles lie within the largest vesicles' diameter from the cell surface. Placental coated vesicles were isolated and examined using negative staining. A polygonally patterened structure was apparent on their surfaces. Analysis of the isolated fraction of coated vesicles using sodium dodecyl sulphate polyacrylamide gel electrophoresis shows the presence of a major protein of molecular weight 180000. This is the same molecular weight that has been given for clathrin, the major protein of the raised polygonally patterned structure on the cytoplasmic surface of coated vesicles from other sources.

Cell Fractionation↗
PubMed1975

Amino acids of Diclidophora merlangi (Monogenea).

The level of free amino acids in Diclidophora merlangi is high, comprising over 500 mu moles/g ethanol extracted dry weight. A single amino acid, proline, constitutes some 70% of the total pool. Analysis of parasite protein and host blood and mucus revealed low proline levels, suggesting that the high free pool content was not related to a requirement for protein systhesis or to its abundance in the diet of the worm. Experiments revealed that proline was not involved specifically in osmoregulation, and the reasons for the large amounts present in Diclidophora remain unknown.

Amino Acids↗
PubMedDate not supplied

Localization of antigen defined by a monoclonal antibody to human 32-kDa insulin-like growth factor-binding protein in the sheep uterus at preimplantation stages of pregnancy.

Employing a murine monoclonal antibody to pregnancy-associated endometrial alpha I-globulin, a 32-kDa insulin-like, growth factor-binding protein (IGF-BP) and major product of the decidualized endometrium in the human, reactivity has been detected in the luminal epithelium of the sheep endometrium during the preimplantation period of pregnancy. Staining was associated with supranuclear regions of the cytoplasm. Reactivity was restricted to the pregnant uterus and was distributed throughout the luminal epithelium in both caruncular and intercaruncular regions. The reactivity was absent from endometrial glands in intercaruncular regions. Staining was first detected at day 10, peaked at day 14 of gestation and was absent by day 16. The implications of the induction of the production of this protein by the preimplantation blastocyst in the luminal epithelium is discussed with reference to the potential role of IGF-BP in IGF action in the embryo.

Animals↗
PubMedDate not supplied

Detection of human and murine trophoblast-specific antigens and an assessment of their species specificity.

The distribution and species specificity of human and mouse trophoblast-specific surface antigens detected by heterologous anti-mouse ectoplacental cone (anti-EPC) trophoblast and anti-human first-trimester trophoblast plasma membrane (anti-TrPM) antisera were assessed using several immunochemical and immunolabelling assays. The findings with immunofluorescence assays using anti-EPC antiserum on monolayer cultures indicate that the expression of mouse trophoblast-specific antigens is restricted to the major trophoblast components of the mouse placenta, as well as pre- and early post-implantation trophoblast, and does not occur on fetal, amnion or tumour tissues. The anti-EPC antiserum does not cross-react with human chorionic villous trophoblast. The human trophoblast-specific antigens also displayed species specificity. The anti-TrPM antiserum showed no evidence of cross-reactivity with rhesus monkey, rabbit, guinea pig or mouse trophoblast by immunodiffusion, crossed immunoelectrophoresis, immunofluorescence or immunoperoxidase labelling.

Animals↗
PubMedDate not supplied

Saccharides localized by fluorescent lectins on trophectoderm and endometrium prior to implantation in pigs, sheep and equids.

Pre-implantation blastocysts together with the corresponding maternal endometrium were obtained from pigs, sheep and equids at known stages of pregnancy. Thin sections of fixed tissue were reacted with FITC-labelled conjugates of lectins specific for alpha-L-fucose, N-acetyl-D-glucosamine, D-galactose, N-acetyl-D-galactosamine and alpha-D-manno- and alpha-D-gluco-pyranosyl residues. The pre-implantation blastocysts of both pig and sheep, throughout the period studied, had a continuous reaction for alpha-L-fucose, which has been suggested to be important in compaction and the expression of SSEA-1 antigen in mouse embryos. Reactivity for N-acetylglucosamine appeared in the blastocysts of both pig and sheep prior to implantation. The staining for fucose and acetylglucosamine was restricted to the apical (maternally apposed) aspect of the trophectoderm. No specific reactivity was observed in horse conceptuses; however, discrete regions of endometrial epithelium stained intensely for N-acetylglucosamine, and may represent 'recognition' sites for the implanting embryo.

Animals↗
PubMedDate not supplied

Equine endometrium at pre-implantation stages of pregnancy has specific glycosylated regions.

Pre- and post-implantation endometrial tissue was removed from equids at known stages of pregnancy. Thin sections of this material were reacted with fluorescein conjugates of several lectins. Two lectins in particular, with specificities for L-fucose and N-acetylglucosamine, reacted strongly with the endometrial epithelium. The reaction for N-acetylglucosamine occurred in small patches on the endometrial epithelium and extended to cover the entire epithelial surface and endometrial glands after implantation. L-Fucose was observed in larger surface deposits particularly at the openings of endometrial glands, but did not extend into them either before or after implantation. These observations indicate changes in glycosylated molecules of endometrial epithelium preceding implantation in equids.

Animals↗
PubMedDate not supplied

Ligand modulation of glial activation: cell permeable, small molecule inhibitors of serine-threonine protein kinases can block induction of interleukin 1 beta and nitric oxide synthase II.

Activated glia (astrocytes and microglia) and their associated neuroinflammatory sequelae have been linked to the disease progression of several neurodegenerative disorders, including Alzheimer's disease. We found that the experimental anti-inflammatory drug K252a, an inhibitor of calmodulin regulated protein kinases (CaMKs), can block induction of both the oxidative stress related enzyme iNOS and the proinflammatory cytokine IL-1 beta in primary cortical glial cultures and the microglial BV-2 cell line. We also found that the profile of CaMKIV and CaMKII isoforms in primary cortical glial cultures and BV-2 cells is distinct from that found in neurons. Knowledge of cellular mechanisms and high throughput screens of a pharmacologically focused chemical library allowed the discovery of novel pyridazine-based compounds that are cell permeable ligand modulators of gene regulating protein kinases involved in the induction of iNOS and IL-1 beta in activated glia. Pyridazine-based compounds are attractive for the development of new therapeutics due to the retention of the remarkable pharmacological properties of K252a and related indolocarbazole alkaloids, and presence of enhanced functional selectivity in a comparatively simple structure amenable to diverse synthetic chemistries.

Animals↗
PubMedDate not supplied

Leucocyte entry and endothelial E-selectin expression following intradermal Propionibacterium acnes administration.

Immune responses in porcine skin to intradermal inoculation of heat-killed Propionibacterium acnes (HKPA), the major bacterial agent associated with human inflammatory acne, were studied. Pigs were chosen as experimental animals because their skin is similar in structure and composition to that of man and because the use of genetically inbred pigs enables leucocytes to be transferred between animals without eliciting rejection responses. Two pigs were sensitized intradermally with 10 mg of HKPA and were challenged 2 weeks later with doses ranging from 1-100 microg of HKPA in various intradermal sites on the ventral aspect of the abdomen. Four further pigs, previously sensitized with Bacillus Calmette-Guérin (BCG) but not HKPA, were challenged with purified protein derivative (PPD) of bovine tuberculin and HKPA. Entry of(51)Cr-labelled peripheral blood lymphocytes (PBLs) over 48 h was studied in all the challenge sites. Peak PBL entry occurred at 4 h, remaining sustained up to 24 h. There was a dose-dependent effect of HKPA on the level of PBL entry, which was antigen-specific, as few leucocytes were seen in PPD-challenge sites in HKPA-sensitized pigs or in HKPA-challenged sites in BCG-sensitized pigs. There was also a substantial influx of(111)Indium-labelled neutrophils into the lesions. Lymphocytes present were predominantly of the CD3(+)CD2(+)T-cell subset, although gammadelta TCR(+)cells were present also, particularly after 24 h. E-selectin was markedly upregulated on dermal endothelium in the P. acnes sites. The histological infiltration and kinetics were similar to those reported in human inflammatory acne.

Acne Vulgaris↗
PubMedDate not supplied

The illusive phantom: does primary care meet patient need following limb loss?

PURPOSE: Anecdotal evidence suggests that General Practitioners (GPs) vary in their understanding of phantom pain and associated factors in amputees. This has implications in that the GP's conception of the problem will determine what treatment or referral is offered. METHOD: The present study aimed to explore GP's knowledge and understanding of phantom limb pain using a postal questionnaire. A sample of 129 GPs responded resulting in a response rate of 38%. RESULTS: The results suggest that GPs underestimate the prevalence, intensity and duration of phantom and residual limb pain. Moreover, inconsistencies in the reasons given for referral to specialist services for the management of phantom pain were reported. CONCLUSION: These findings have serious implications for the management of phantom limb pain, disability and psychological distress in amputees in that GPs not only provide first line treatment, but are also the gatekeepers for referral to other services. Given this, the role of other professionals within the primary health care team may prove an additional resource for providing both support and accurate information to amputees in the community.

Adult↗
PubMedDate not supplied

Mercy mission.

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Attitude of Health Personnel↗
PubMedDate not supplied

The vasectomized testis.

We have performed a qualitative study on effects of vasectomy on the testicular structure. Vasectomy performed with the traditional technique changes testicular structure. At first, the injuries are slight and restricted, but gradually, and in a time-dependent manner, become more severe and extensive. Ultrastructure studies indicate that the spermatogonia and Sertoli's cells are the most resistant to vasectomy, and are even observed in some regenerating testes lacking a complete germinal epithelium. Morphometric studies revealed a decrease in epithelial depth, an increase in the thickness of the basement membrane and in surface of the interstitial space, all significant (P < 0.01) with respect to the control. However, the percentage of the interstitial tissue occupied by cells, did not show any significant difference. We propose that the increase of intraluminal pressure is the essential factor that provokes testicular atrophy.

Animals↗
PubMedDate not supplied

Uncommon women.

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History of Nursing↗