Search PubMed⌕ Search

Biomedical subjects

D Scott

Publications and source records attributed to D Scott.

At least 343 records · Page 19Linked to original sources
PubMed1984

Immunogenicity of biotinylated hapten-avidin complexes.

The efficacy of avidin as a carrier for the generation of anti-hapten antibodies was assessed in mice by immunization with complexes of avidin and synthetic peptides containing biotin and an epsilon-dinitrophenyl (DNP) lysine residue. The synthetic haptens were constructed with 0, 1 or 2 6-aminocaproyl groups as spacers between the biotin and DNP-lysine moieties. Complexes without a spacer did not induce anti-DNP antibody responses, while those with two spacers induced stronger responses than those with only one spacer. However, the anti-DNP responses to avidin-biotinylated hapten complexes were considerably weaker than responses to a conventional hapten-protein conjugate (DNP-ovalbumin), and, like "T-independent" antigens, failed to induce significant immunological memory. The distribution of isotypes in the anti-DNP antibodies produced to avidin-biotin-6-aminocaproyl-epsilon-DNP-lysine-alanine and DNP-ovalbumin was similar, but the former antigen induced significantly lower levels of antibody in (CBA/N X BALB/c) F1 male mice with the xid defect than in phenotypically normal female littermates, and also induced significant responses in nu/nu mice, in contrast to DNP-ovalbumin. These findings suggest that there is at least a "T-independent" or "T-efficient" component in the response to avidin-biotin complexes, perhaps due to the tetrameric structure of the molecule. Estimates of the depth of the receptor site for biotin were obtained by using the complexes to competitively inhibit the binding of anti-DNP antibody to plates coated with DNP-protein. The findings were consonant with the data on immunogenicity (capacity to induce anti-DNP antibody responses) and suggested that the receptor site has a depth of 16-26 A.

Alanine↗
PubMed1984

Use of sonographic estimated fetal weight in the prediction of intrauterine growth retardation.

The value of sonographic estimated fetal weight (SEFW) in the antenatal detection of intrauterine growth retardation (IUGR) was tested in a population of 179 patients, at risk for IUGR, who had a SEFW determination within 15 days of delivery. A nomogram was developed and three zones of SEFW were defined. Sixty percent of the population had an SEFW determination in Zone I, and no IUGR occurred in this group. Thirty-one percent of the scanned population fell into Zone II, with a 24% prevalence of IUGR. Nine percent of referred patients were in Zone III; 82% of these were growth retarded at birth. SEFW is a useful tool in the antenatal diagnosis of IUGR.

Birth Weight↗
PubMed1984

Magnesium absorption in mature ewes infused intrarumenally with magnesium chloride.

The effects of magnesium supplementation on Mg absorption proximal and distal to the pylorus in ewes maintained on a grass diet were investigated using a combination of balance, digesta flow and electropotential measurements. Three mature ewes each received by intrarumenal infusion a supplement of 0, 1, 2 and 3 g Mg/d in sequence over four 10-d periods. Net Mg absorption distal to the pylorus took place down its electrochemical gradient, although the quantity absorbed remained small during the control and first infusion periods. The bulk of Mg absorption occurred before the pylorus and, during the control and first infusion periods, took place against its electrochemical gradient. The net Mg absorption proximal to the pylorus rose with declining efficiency as Mg intake was increased. It is suggested that saturation of the absorption process at this site was occurring.

Animals↗
PubMed1984

The effect of variation in phosphorus intake on net intestinal phosphorus absorption, salivary phosphorus secretion and pathway of excretion in sheep fed roughage diets.

Mature sheep fitted with rumen and duodenal cannulae and fed either pelleted hay or grass diets were given supplements of Na2HPO4 by continuous infusion into the rumen and the effects on salivary phosphorus secretion, intestinal phosphorus absorption and pathway of excretion were studied. Little phosphorus was excreted in the urine in control periods and little increase was seen in response to phosphorus supplementation, most of the extra phosphorus given being recovered in the faeces. Infusion of phosphorus into the rumen led to an increase in the flow of phosphorus to the intestine, an increase in absorption, a rise in plasma phosphate level and an increase in salivary phosphorus secretion while withdrawal of supplementary phosphorus was seen to have the opposite effects. In separate studies short sections of the upper small intestine temporarily isolated from the normal flow of digesta were perfused with solutions containing NaH2PO4 (5-50 mmol.l-1). Phosphorus absorption increased with increasing concentration though the relationship was curvilinear such that absorptive efficiency fell from around 0.7 at 5 mmol.l-1 to around 0.35 at a concentration of 50 mmol.l-1. The significance of these results in relation to the control of phosphorus balance in ruminants is discussed.

Absorption↗
PubMed1984

The effects of intravenous phosphate loading on salivary phosphorus secretion, net intestinal phosphorus absorption and pathway of excretion in sheep fed roughage diets.

Mature sheep fitted with rumen and duodenal cannulae and fed either pelleted hay or grass diets were given supplementary phosphorus by continuous intravenous infusion and the effects on salivary phosphorus secretion, intestinal phosphorus absorption and pathway of excretion were studied. In control periods little phosphorus was excreted in the urine, the faeces being the major pathway for excretion. Infusion of phosphorus increased both urine and faecal phosphorus excretion though in sheep fed the hay diet the urine response was much less marked than in those fed the grass diet. This was not due to differences in plasma phosphate levels but rather to differences in renal tubular reabsorptive efficiency, though the reason for this is at present unclear. Intravenous phosphate loading had little effect on salivary phosphorus secretion, most of the increase in faecal phosphorus excretion being the result of reduced reabsorption within the intestine. The significance of these changes in relation to the control of phosphorus balance in ruminants is discussed.

Absorption↗
PubMed1984

Differential rates of loss of chromosomes aberrations in rat thyroids after X rays or neutrons.

Rat thyroid glands were exposed in vivo to 5.5-Gy X rays or 2.75-Gy neutrons (14.7 MeV) and cell proliferation was stimulated by goitrogen treatment at various intervals up to 48 weeks postirradiation. The amount of chromosome damage in stimulated follicular cells declined much more slowly after neutron than X irradiation, suggesting differential repair. This observation may be relevant to the question of residual cellular damage and oncogenesis after X rays and neutrons.

Amitrole↗
PubMed1983

Anxiety states: a preliminary report on the value of connective tissue massage.

Five patients who presented with symptoms of tension and anxiety were subsequently referred to a physiotherapist and treated with Connective Tissue Massage. Psychophysiological recordings of heart rate, frontalis EMG, skin resistance and forearm extensor EMG were taken before and after treatment. All patients showed a significant response to treatment in one or more of the psychophysiological parameters. Results are discussed in relation to the hypothesis that each individual has a unique stress response pattern. Preliminary findings proved interesting and supported clinical findings with regard to the effectiveness of this treatment for some patients suffering from Anxiety States.

Adult↗
PubMed1983

Ca+2 dependence of gonadotropin-releasing hormone-stimulated luteinizing hormone secretion: in vitro studies using continuously perifused dispersed rat anterior pituitary cells.

A continuously perifused dispersed rat anterior pituitary cell system was used to determine the importance of calcium (Ca+2) on the release of LH by GnRH. In response to continuous exposure to 10 nM GnRH, LH was released in a biphasic fashion; arbitrarily, phase I was defined as being the LH released during the initial 40 min and phase II as the subsequent release. Withdrawal of Ca+2 from the perifusion medium during phases I or II of LH release led to a rapid inhibition of the LH secretion. Cells were exposed to GnRH for 2.5 min, washed with medium for 30 min, and then reexposed to GnRH for 30 min. This sequence was repeated 1 h later under identical conditions in the presence of a Ca+2 blocking agent; D600 (20 or 100 microM). D600 inhibited both the 2.5- and the 30-min GnRH-stimulated LH release. The results were expressed as the ratio obtained by dividing the total LH released during the second GnRH exposure (either 2.5 or 30 min) by the total LH released during the respective initial GnRH exposure of same duration. For the cells perifused with 20 microM D600 the ratios +/- SE (D600 vs. control) were 0.48 +/- 0.06 vs. 1.28 +/- 0.13 (P = 0.0001) and 0.29 +/- 0.05 vs. 1.01 +/- 0.08 (P less than or equal to 0.0001) for the 2.5- and 30-min exposures, respectively. For the cells perifused with 100 microM D600 the ratios +/- SE (D600 vs. control) were 0.18 +/- 0.05 vs. 1.28 +/- 0.13 (P less than or equal to 0.00001) and 0.12 +/- 0.03 vs. 1.01 +/- 0.08 (P = 0.002) for the 2.5- and 30-min exposures, respectively, revealing an even more profound inhibitory effect of D600 on GnRH stimulated LH secretion. Our data both confirm previous reports that Ca+2 is involved in LH release and demonstrate that Ca+2 is an essential requirement during both phases of GnRH-stimulated LH release in perifused dispersed rat anterior pituitary cells.

Animals↗
PubMed1982

Tumor immunity to murine plasma cell tumors. VII. Expression of H-2 and tumor antigens on Ig synthesis variants of MPC-11.

As a part of our continuing investigations directed toward defining the nature of the antigens on murine plasmacytomas (PCT), MPC-11 and two immunoglobulin (Ig) synthesis variants of this cell line were examined for H-2 and tumor-associated antigen (TAA) expression, and for the possible role of H-2 in the cytotoxic T lymphocyte response to TAA. The tumor lines studied were MPC-11 (an IgG2b producer), MPC-11,662 (a variant which produces only light chains), and NP.2 (a variant which produces neither Ig chain). Both H-2 expression, which was analyzed by flow cytometry and by cold target cell blocking of the activity of cytotoxic T lymphocytes (CTL) generated in allogeneic cultures, and TAA expression, which was analyzed by cold target cell blocking of the activity of tumor-specific CTL generated in syngeneic cultures, were found to be quantitatively similar on the three lines. When a possible association between H-2 and TAA expression was examined by testing the ability of anti H-2 sera to block tumor-specific CTL directed against MPC-11, no association between H-2 and TAA was detected. The results of these studies provide new information about H-2 and TAA expression on murine PCT. Furthermore, they suggest that changes in H-2 and TAA expression which have been reported to sometimes accompany loss of Ig synthesis may represent independent genetic, phenotypic, or metabolic variations, rather than alterations linked to the loss of Ig synthesis. In addition, these results, in agreement with out previous studies on MPC-11, support the concept that there is not an obligatory association of TAA with H-2 on the surface of murine PCT. Because these results differ from those reported in some other systems in which an association between H-2 and TAA on murine PCT was demonstrated, it must be emphasized that the TAA of PCT appear to be quite heterogeneous, and more investigations will be necessary in order to clearly define these antigen and the T-cell response to each of them.

Animals↗
PubMed1982

Clonal preadipocyte cell lines with different phenotypes derived from murine marrow stroma: factors influencing growth and adipogenesis in vitro.

We have isolated continuously growing cell lines derived from mouse bone marrow stroma. These cell lines were independently obtained, and though they showed morphologies ranging from the epithelioid to the fibroblastoid patterns, they all differentiated into adipocytes. Subclones obtained from two cell lines had a very high frequency (90-100%) of differentiation into adipocytes after two or three weeks of arrested growth. Though extensive accumulation of lipid often mechanically impaired mitosis, the cells committed to adipocytes did not suffer an irreversible loss of proliferative capacity. Adipogenesis was obtained in conditions similar to those required for fat cell formation in long-term bone marrow culture. The cell lines were found to be insensitive to insulin as a signal of adipocyte differentiation. The ultrastructural characteristics of the preadipocytes and fat cells are also similar to those of the fat cells developing in long-term bone marrow culture. As such, these cell lines should prove useful for analysing cell/cell interactions in haemopoiesis.

Adipose Tissue↗