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Biomedical subjects

R Cameron

Publications and source records attributed to R Cameron.

At least 91 records · Page 5Linked to original sources
PubMed1989

Glomerular epithelial detachment, not reduced charge density, correlates with proteinuria in adriamycin and puromycin nephrosis.

To identify the structural change coincident with increased glomerular permeability in both adriamycin (ADR) and puromycin-aminonucleoside (PAN) nephrosis, we explored the temporal correlation between developing proteinuria, the reduction in glomerular polyanions, and the detachment of epithelium from glomerular basement membrane (GBM). Sprague-Dawley rats received a single tail-vein injection of PAN (150 mg/kg), ADR (7.5 mg/kg) or saline. Nephrotic-range proteinuria appeared between days 2 to 5 in the PAN-treated and days 5 to 10 in the ADR-treated rats. The GBM heparan sulfate charge density and epithelial membrane sialic acid (SA) content were determined before, during and after the rise in proteinuria. Polyethyleneimine was used to detect heparan sulfate and the number staining of renal cortical slices was used to detect heparin sulfate and the number of sites/microns GBM in the lamina rara externa were counted on electron micrographs (magnification x60,000). Controls had a regular distribution of polyethyleneimine 20.19 +/- 1.72 sites/microns (X + SD). In ADR rats, the polyethyleneimine density decreased by day 5, 18.61 +/- 1.79 sites/microns (p less than 0.05) which persisted to day 15, 17.38 +/- 1.27 sites/microns (p less than 0.02). PAN rats, by day 1, had significant reduction, 14.94 +/- 1.47 sites/microns (p less than 0.05), which persisted to day 20. The total membrane-bound SA content of isolated glomeruli was analyzed with a modified Warren's method. The SA content in control glomeruli was 46.8 +/- 8.0 nmol/mg glomerular protein (X +/- SD). In ADR rats, there was significant decrease in SA content to 84 +/- 3% of control (p less than 0.01) at day 15. In PAN rats, by day 2, the SA content was decreased to 73 +/- 18% of control (p less than 0.05). In both models, scanning and transmission electron microscopy revealed epithelial foot process fusion, loss of slit diaphragms, and vacuolization before increased proteinuria. Epithelial detachment from the GBM and rupture of vacuoles occurred coincidently with rapid development of nephrotic proteinuria in both models. In summary, reduced GBM heparan sulfate and epithelial SA content do not correlate with the onset of altered glomerular permeability, whereas epithelial detachment is coincident with the development of massive proteinuria in both ADR and PAN nephrosis.

Animals↗
PubMed1988

Hepatotoxicity to dogs of horse meat contaminated with indospicine.

An outbreak of liver disease which killed more than 30 dogs at Alice Springs was associated with feeding meat from horses, some of which had developed Indigofera linnaei poisoning (Birdsville horse disease). Affected livers were small, nodular and yellow. There was associated jaundice, ascites, elevation of alanine aminotransferase levels in serum, a tendency to bleed, and signs of hepatic encephalopathy. Histologically, livers showed periacinar necrosis, collapse and haemorrhage, with severe swelling, vacuolation and cholestasis in remaining hepatocytes. Indospicine, a toxic amino acid found in the genus Indigofera, was detected in samples of suspect horsemeat. Experimental feeding of horsemeat containing 16 mg indospicine/kg for 32 days produced periacinar necrosis and hepatocellular swelling in 2 dogs, although neither died nor showed clinical illness. In another experiment, intakes of as little as 0.13 mg indospicine/kg bodyweight/day for 70 days produced periacinar liver lesions, and indospicine concentrations in serum, muscle and liver rose during this period to 3.9, 7.9 and 17.5 mg/kg, respectively. It was concluded that meat from horses grazing I. linnaei can be hepatotoxic for dogs, and that this toxicity may be related to its indospicine content.

Amino Acids↗
PubMed1987

Imaging studies and the prognostic value of serum calcitonin in staging small-cell lung cancer.

The controversial prognostic significance of serum calcitonin in small-cell lung cancer (SCC) prompted this retrospective study relating serum levels to (1) stage of disease [limited disease (LD) vs. extensive disease (ED)], (2) imaging studies of metastases to bone, liver, and brain, and (3) survival. Of the 127 previously untreated patients with SCC presenting from 1979 to 1984, calcitonin levels could be compared to the stage of the disease in 69 patients (25 LD and 44 ED) and to various staging procedures including 99mTc methylene diphosphonate bone scans (63 patients), 99mTc sulfur colloid liver-spleen scans (64 patients), computed tomography of the head (63 patients) and serum calcium (61 patients). 71% (49/69) of patients had elevated calcitonin of whom 65% (32/49) had ED. 29% (20/69) had normal levels of whom 60% (12/20) had ED. 40% (18/45) of patients with raised calcitonin had liver metastases. 100% (19/19) with normal calcitonin had no liver involvement. Two patients with hypercalcemia and increased calcitonin had extensive bony metastases. The survival experiences of patients with normal and elevated serum calcitonin levels were analyzed. No significant differences were found within each stage or in the group overall. The positive correlation of serum calcitonin to liver metastases was statistically significant. No such relationship could be demonstrated with stage of disease, bone metastases, brain metastases, or survival.

Calcitonin↗
PubMed1987

Protein production and secretion in exocrine cells.

Acinar cells of exocrine glands are highly specialized for producing, storing, and discharging secretory proteins for use on surfaces that represent interfaces between the organism and the surrounding environment. These functions are achieved through the secretory pathway that includes a series of functionally distinct intracellular compartments--the endoplasmic reticulum, subcompartments of the Golgi complex, and the secretion granule in which exportable macromolecules are stored at high concentrations. Most secretion occurs by granule exocytosis in response to external hormonal or neural stimuli. Although these processes have been traced in a variety of morphological and biochemical studies, very little is known about the mechanisms involved in facilitating and maintaining secretory storage, orchestrating discharge at the apical cell surface, and in ensuring conservation and re-internalization of the granule membrane. Recent studies initiated on cell fractions obtained from the rat parotid gland have provided significant insight into the protein storage conditions that prevail in the granule interior and the components of the granule membrane that are likely to be involved in general secretory function such as exocytosis.

Animals↗
PubMed1986

Pleomorphic adenoma in the breast of a human female. Aspiration biopsy findings and receptor determinations. Case report.

A case of multiple pleomorphic adenomas ("mixed" tumour of salivary gland type) of the breast is reported. This rare benign tumour can be misinterpreted as a malignant tumour both clinically and radiologically. The aspiration biopsy findings suggested cystosarcoma phyllodes. Oestrogen and progesterone receptor determinations revealed medium high levels, comparable to carcinoma of the breast.

Adenoma, Pleomorphic↗
PubMed1986

Delineation of two defects responsible for T-cell hyporesponsiveness to concanavalin A in MRL congenic mice.

MRL-lpr mice and their congenic counterparts MRL-+ spontaneously develop an autoimmune disease that resembles systemic lupus erythematosus in humans. The two strains, although congenic, differ by a considerable number of disease parameters, reflecting the expression of the lpr autosomal recessive gene. One paradox that has developed out of the work utilizing the congenic mice is that the gene responsible for lymphoproliferation also appears to be responsible for the inability of T cells to respond to proliferative signals in vitro. In this paper we investigated a possible lpr gene-encoded macrophage defect in these mice. It was found, however, that both the MRL-+ and MRL-lpr mice failed to divide in response to Con A, the lack of division correlating with an inability to secrete the growth promoter interleukin-2. In MRL-+ mice and young MRL-lpr mice this non-responsiveness was corrected by the addition of normal CBA PEC. The defect could not be explained by a failure of MRL-+ or MRL-lpr peritoneal exudate cells to quantitatively or qualitatively provide a source of interleukin-1 to Con A-activated T cells or by the possibility that the peritoneal exudate cells were blocked in their function by the presence of sera-derived autoantibodies and/or immune complexes on their membranes. We postulate that the inability of T cells to proliferate in MRL congenic mice can be explained by two defects: the failure of antigen-presenting cells in MRL-+ and MRL-lpr to provide the necessary signals to immunocompetent T cells, this defect not being associated with the lpr gene, and the lpr gene controlled outgrowth of a unique T-cell population that cannot respond in our assay system.

Animals↗
PubMed1985

Radiosensitization effects of nicotinamide on malignant and normal mouse tissue.

Inhibitors of the chromatin-associated enzyme adenosine diphosphate ribosyltransferase have been found to inhibit DNA strand rejoining and to potentiate lethality of DNA-damaging agents both in vivo and in vitro. We have in this work examined the radiosensitizing potential of one such inhibitor, nicotinamide, on tumor tissue by using transplanted C3H mouse mammary adenocarcinomas and on normal tissue in a tail-stunting experiment using BALB/cA mice. Our data indicate a radiosensitizing effect of nicotinamide on tumor cells as well as on normal tissue. The data indicate a possible role of adenosine diphosphate ribosyltransferase inhibitors as a sensitizing agent in the radiotherapy of malignant tumors.

Animals↗
PubMed1984

The effects of education and group discussion in the post myocardial infarction patient.

An education and group discussion program administered to a randomly selected group of post myocardial infarction subjects failed to produce any differences in a large number of behavioral and psychological measures. These included smoking behavior, health status, social and recreational status, family and marital life and vocational activities, as well as measures of anxiety, depression, and health locus of control. Treated subjects were slower to return to work than controls and were less likely to have returned to work by the end of the study. More individuals in the treatment group were receiving compensation and this may have been a factor in delaying return to work. Since the majority of our subjects had a very optimistic attitude toward their eventual recovery, there was limited room for improvement. We suggest that cardiac rehabilitation be directed only at those patients with "negative" attitudes, and with more than usual anxiety and depression.

Adaptation, Psychological↗
PubMed1983

Synapsin I (protein I), a nerve terminal-specific phosphoprotein. I. Its general distribution in synapses of the central and peripheral nervous system demonstrated by immunofluorescence in frozen and plastic sections.

Synapsin I (formerly referred to as protein I) is the collective name for two almost identical phosphoproteins, synapsin Ia and synapsin Ib (protein Ia and protein Ib), present in the nervous system. Synapsin I has previously been shown by immunoperoxidase studies (De Camilli, P., T. Ueda, F. E. Bloom, E. Battenberg, and P. Greengard, 1979, Proc. Natl. Acad. Sci. USA, 76:5977-5981; Bloom, F. E., T. Ueda, E. Battenberg, and P. Greengard, 1979, Proc. Natl. Acad. Sci. USA 76:5982-5986) to be a neuron-specific protein, present in both the central and peripheral nervous systems and concentrated in the synaptic region of nerve cells. In those preliminary studies, the occurrence of synapsin I could be demonstrated in only a portion of synapses. We have now carried out a detailed examination of the distribution of synapsin I immunoreactivity in the central and peripheral nervous systems. In this study we have attempted to maximize the level of resolution of immunohistochemical light microscopy images in order to estimate the proportion of immunoreactive synapses and to establish their precise distribution. Optimal results were obtained by the use of immunofluorescence in semithin sections (approximately 1 micron) prepared from Epon-embedded nonosmicated tissues after the Epon had been removed. Our results confirm the previous observations on the specific localization of synapsin I in nerve cells and synapses. In addition, the results strongly suggest that, with a few possible exceptions involving highly specialized neurons, all synapses contain synapsin I. Finally, immunocytochemical experiments indicate that synapsin I appearance in the various regions of the developing nervous system correlates topographically and temporally with the appearance of synapses. In two accompanying papers (De Camilli, P., S. M. Harris, Jr., W. B. Huttner, and P. Greengard, and Huttner, W. B., W. Schiebler, P. Greengard, and P. De Camilli, 1983, J. Cell Biol. 96:1355-1373 and 1374-1388, respectively), evidence is presented that synapsin I is specifically associated with synaptic vesicles in nerve endings.

Animals↗
PubMed1982

Immunohistochemical evidence for the lack of amyloid P component in some intracerebral amyloids.

Sections of brain tissue from patients with Alzheimer's disease with amyloid deposits in vessels, in plaques, and within nerve cells were studied by means of an immunoperoxidase method using a specific antiamyloid P component (AP) antiserum. Amyloid deposits in vessels were found to be strongly positive for protein AP, whereas the Alzheimer's plaques and the neurofibrillary tangles were negative or only weakly positive. The absence of protein AP in some intracerebral amyloid deposits might be due to an inability of the protein AP in some intracerebral amyloid deposits might be due to an inability of the protein to penetrate the blood-brain barrier. These findings support the theory that protein AP is absorbed to already formed amyloid fibrils, but the possibility that it may participate in the formation of vascular amyloid cannot be dismissed. The findings also indicate that protein AP is not necessary for the formation of amyloid fibrils at least in some forms of cerebral amyloidosis.

Alzheimer Disease↗
PubMed1981

X-ray microanalysis of fluid spaces in the frozen cochlea.

The cochlea is quick-frozen and then opened while under liquid nitrogen to expose the scalae of all turns in the mid-modiolar section. Still under liquid nitrogen, the cochlea is transferred to the cold stage of a pre-vacuum chamber especially constructed for attachment to the scanning electron microscope. Under partial vacuum, it is moved to the cold stage in the high vacuum chamber of a field-emission scanning electron microscope. Energy dispersive X-ray analysis demonstrates the relative levels of sodium, potassium, and chlorine in the fluid spaces of the cochlea.

Animals↗