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Biomedical subjects

J McDougall

Publications and source records attributed to J McDougall.

At least 55 records · Page 3Linked to original sources
PubMed1983

Tertiary structure of the eukaryotic ribosomal 5 S RNA. Accessibility of phosphodiester bonds to ethylnitrosourea modification.

The tertiary structure of the eukaryotic ribosomal 5 S RNA was examined using ethylnitrosourea reactivity as a probe for phosphodiester bonds. In three different 5 S RNAs of diverse origin the reactivity was restricted to the same three regions of the sequence, corresponding to residues G 99-A 101, A 88-G 89, and G 75 in the rat 5 S RNA molecule. All of these restricted residues are in highly conserved sequences; five of the residues (G 75, G 89, G 99, A 100, and A 101 in the rat) are present in all 5 S RNAs. The results indicate that, as has been suggested for the secondary structure, the tertiary structure of the 5 S RNA is also highly conserved. Based on these data, a working model for the tertiary structure is suggested which is consistent with previous studies on the structure of the free RNA and 5 S RNA-protein complexes.

Animals↗
PubMed1983

Renal handling and acute urinary electrolyte effects of aminoglycoside antibiotics: use of a solitary renal autotransplant in the conscious sheep.

Renal handling of the aminoglycoside antibiotics gentamicin and tobramycin were studied before and after one hour of constant intravenous infusions adjusted to maintain a concentration of 15 micrograms/mL. A solitary renal autotransplant model in four conscious volume replete 40 Kg sheep was used. This unique surgical preparation allows sampling of renal arterial and renal venous blood as well as urine drained through an exteriorized parotid-ureteral fistula. This surgical preparation has considerable potential in renal pharmacology since it uses a conscious, large animal. Baseline studies in this preparation demonstrated normal, 51CrEDTA and 125 I PAH, clearances which were unaffected by the drugs. Aminoglycoside binding to pooled sheep sera was 11% at physiologic PH, calcium and magnesium concentrations. A-V difference was 1.3 +/- .3 micrograms/mL and extraction by the kidney was 9 +/- 3.2% with no differences between gentamicin and tobramycin. Clearance of gentamicin was 84% and tobramycin 86% of GFR. There was no evidence of tubular injury as evidenced by unchanged urinary beta-2 microglobulin excretion. Serum Na, K, Ca and Mg did not change over the course of the study. Both drugs caused a prompt decrease in absolute and fractional sodium excretion while only gentamicin produced a kaliuresis. Early aminoglycoside effects on electrolyte balance may be an eventual determinant of nephrotoxic potential rather than differences in renal drug handling.

Aminoglycosides↗
PubMed1983

Muscle changes in ankylosing spondylitis.

Muscle biopsy of the quadriceps femoris was carried out in 20 patients with classical ankylosing spondylitis (AS). Histological and histochemical studies revealed changes in all biopsies to a varying degree. Central migration of nuclei was present in 80%, reduced fibre size with some atrophy in 40%, localized reaction to acid phosphatase in 75% and a peripheral condensation of reaction product to NADH-TR stain in 55% of biopsies. Furthermore 14 out of 16 patients, whose quadriceps strength was measured, were found to be below the predicted values, when compared to healthy controls of similar weight, and quantitative surface electromyography in 10 showed lower mean power frequency than in controls. A raised plasma creatine kinase was found in only two patients. It is concluded that muscle changes occur in AS and these may account for some of the clinical features of the disease.

Adult↗
PubMed1982

Monoclonal antibodies to cytomegalovirus: rapid identification of clinical isolates and preliminary use in diagnosis of cytomegalovirus pneumonia.

Two monoclonal antibodies which react specifically with cells infected by cytomegalovirus (CMV) are described. One antibody, 6-E3, reacts with a 72,000-dalton protein that appears early in infection and remains localized in the cell nucleus. The other antibody, 6-C5, reacts with an 80,000-dalton protein that appears late in infection and remains localized in cytoplasmic inclusion bodies. Both monoclonal antibodies react with conventional laboratory strains of CMV and can be used in immunofluorescence assays to identify clinical isolates of CMV in culture. Preliminary tests on lung tissues from patients with CMV pneumonia show that only antibody 6-C5 detects CMV infection in primary clinical specimens. A comparison of culture, histological, and immunological methods demonstrates that the monoclonal antibodies possess sufficient specificity and sensitivity to warrant their continued development as immunodiagnostic tools for the detection of CMV infection in both tissue culture and tissues obtained directly from patients.

Antibodies, Monoclonal↗
PubMed1982

Alexithymia: a psychoanalytic viewpoint.

Alexithymic phenomena may result from a variety of psychological sources. Psychoanalytic observation of psychosomatic patients (and others as well) reveals that the inability to name, recognize, contain or work through one's affective states is frequently one manifestation of defensive structures of a psychotic kind (more radical than denial which deals with certain neurotic anxieties). Such massive defense has been created as a bulwark against various dangers, such as (1) psychotic anxieties (fear of mental or physical fragmentation; loss of identity-feeling; danger of uncontrollable, explosive action); (2) profound perturbation concerning the narcissistic self-image and its fluctuations, and (3) pathological formation of the ego-ideal structure concerning affective experience. All of these may contribute to the creation of alexithymic defects.

Affect↗
PubMed1981

Characterization of polymyositis infiltrates using monoclonal antibodies to human leucocyte antigens.

Frozen serial sections of muscle from 15 patients with polymyositis and three normal controls were studied by indirect immunofluorescence with a panel of mouse monoclonal antibodies to various human leucocyte components. The results showed good correlation with conventional histology. In addition, large numbers of T lymphocytes were identified in those cases with a marked inflammatory infiltrate. Many of the T cells probably bear HLA-DR antigen as the anti-HLA-DR antibody stained as many cells as the anti-leucocyte antiserum. This strongly suggests that the T cells present are 'activated'. In two patients HLA-DR-positive material was identified apparently diffusing from the infiltrates into muscle fibres suggesting its release as a soluble factor. In one case, structures with the appearance of giant cells were seen. The method promises to provide new information on the nature of infiltrating leucocytes which may provide more accurate diagnostic and prognostic information than conventional histology alone.

Adult↗
PubMed1978

Endocrine-like cells in the terminal bronchioles and saccules of human fetal lung: an ultrastructural study.

An ultrastructural study of Kulschitsky cells was made on lung tissue from five human fetuses of gestational ages between 18 and 25 weeks. The cells were found to occur with relative frequency throughout the bronchi and bronchioles, as well as in the developing saccules. This report describes in detail the cells of the terminal bronchioles and saccules, where their long cytoplasmic processes weave through the epithelium and come into contact with intercellular spaces and the lumen. The cytoplasmic organelles have an orderly arrangement comparable to secreting cells. Dense core vesicles characterise the cytoplasm but clear vesicles and some with less dense, diffuse cores are also present, and may be seen outside the plasma membrane and in the interstitial spaces. The K-cells are usually colsely associated with capillaries or smooth muscle cells across the basement membrane. In addition, the rare occurrence of a small unmyelinated nerve fibre in the vicinity of a K-cell in a terminal bronchiole raises the possibility that the cells fulfill a type of 'mini receptor' role in addition to their probable vasoactive one. Evidence is given that K-cells divide in human fetal lung.

APUD Cells↗
PubMed1976

Some ultrastructural aspects of mitosis and early differentiation in human foetal lung.

In rapidly dividing human foetal lung cells there is evidence of synthesis of extra membrane prior to mitosis. During prophase the nuclear envelope breaks down and is conserved as long double or complex stacks during the following stages of mitosis. It is suggested that the membrane is retained partly for incorporation into the daughter cell nuclear envelopes and partly for the formation of RER. The relevance of the observations to the biochemical data in the literature concerning the formation of intracellular membranes is discussed briefly.

Cell Differentiation↗
PubMed1975

The development of the human type II pneumocyte.

Portions of lung from 25 human foetuses between 12 and 26 wk of gestational age were examined for ultrastructural changes during maturation of the epithelial cells. In 10 cases type I pneumocytes and in five cases type II cells were differentiated. The changes associated with the formation of lamellar inclusion bodies in type II cells are described. It is concluded that this is a synthetic process in which protein and lipid assembly are important. Changes in glycogen and participation of dense bodies are striking.

Bronchi↗