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Biomedical subjects

D Grant

Publications and source records attributed to D Grant.

At least 235 records · Page 13Linked to original sources
PubMed1990

Teaching reading comprehension skills to spina bifida children.

Thirteen children with spina bifida (mean age 11 yrs 11 mths) and a mean reading comprehension reading deficit of 10.5 mths were enrolled into a remedial programme. The withdrawal single case study methodology was used (baseline--5 weeks, treatment--5 weeks, withdrawal--12 weeks). Each child was seen twice a week for 15 minutes during both the baseline and treatment stages. A teaching programme based on a close technique was utilized only during the treatment stage. The technique involved teaching each child a strategy for systematically examining a text for meaning. A halving of the comprehension deficit was observed by the end of the treatment stage, with a mean regression of almost 3 months at the end of the withdrawal stage. No relationship between IQ and gains in reading comprehension was observed. The results may indicate that, in part, reading comprehension deficits are performance deficits which, in turn, may be mediated by attentional strategies.

Adolescent↗
PubMed1990

Absence of effect of dipyridamole on renal and platelet function in diabetes mellitus.

We evaluated the effect of dipyridamole (5 mg/kg/day) for 12 months on renal and platelet function in 53 children with insulin dependent diabetes mellitus (IDDM) in a prospective double blind placebo controlled trial. Urine albumin excretion (expressed as the geometric mean albumin to creatinine concentration ratio (UA/UC) was measured every three months throughout the study. At 12 months, the geometric mean UA/UC was no different in diabetic children receiving dipyridamole, 0.60 mg/mmol, when compared with those receiving placebo, 0.87 mg/mmol. Glomerular filtration rate, urinary excretion of retinol binding protein, and N-acetyl-beta-D-glucosaminidase (NAG), blood pressure, and spontaneous platelet aggregation in response to stirring whole blood did not differ between the two groups at 12 months. Subgroup analysis to include only those children with high UA/UC before entry into the study also failed to show an effect of the drug on UA/UC. Eleven children had either persistently high UA/UC (n = 8: four on dipyridamole, four on placebo) or progression to high UA/UC (n = 3: two on dipyridamole, one on placebo). These children had significantly higher urinary excretion of retinol binding protein and NAG, bigger kidneys, and higher diastolic blood pressure both before and after treatment than the remaining 42 children, whereas there was no difference in spontaneous platelet aggregation between the two groups. These observations on the associations between UA/UC and other parameters of renal function suggest that measurement of 'tubular' proteins and diastolic blood pressure as well as UA/UC may contribute to the identification of those at risk of developing nephropathy.

Adolescent↗
PubMed1989

Infrared spectroscopy of chemically modified heparins.

Analysis by i.r. spectroscopy of natural and chemically modified heparins suggests that the N-sulphonate group of these polymers may vibrationally absorb radiation at two distinctly different frequencies. This property may reflect the existence of different conformational states important in the biological activities of the polymers. Examination of carboxylate- and N-acetyl-group absorbances of these polymers accords with the possibility that one of these polymer conformational states involves interaction between juxtaposed N-sulphonate and carboxylate groups. In heparin bearing large quantities of artificially introduced N-acetyl groups, an interaction between carboxylate and N-acetyl groups may also occur.

Heparin↗
PubMed1989

Inhibition by glycosaminoglycans of CaCO3 (calcite) crystallization.

Of a range of glycosaminoglycans, heparin and heparan sulphate were the most effective inhibitors in vitro of CaCO3 (calcite) crystallization as assayed by conductimetric measurements. The possible role of such glycosaminoglycans in modulating calcium-salt crystallizations in vivo is discussed.

Calcium Carbonate↗
PubMed1989

Association of fibronectin with the microfibrils of connective tissue.

The association of fibronectin with the microfibrils of connective tissue was examined in the zonular fibers of the mouse eye by immunohistochemical methods at the light and electron microscopic level. Mouse eyes fixed in formaldehyde were embedded either in paraffin for immunostaining by the peroxidase-antiperoxidase (PAP) method or in Lowicryl for immunolabeling by antirabbit globulin antibodies bound to 5 or 15 nm gold particles. Ultrastructural studies were also carried out after glutaraldehyde perfusion. Both the PAP and immunogold procedures demonstrated the association of fibronectin with microfibrils. After immunolabeling with 5 nm gold particles, examination at high magnification localized fibronectin to fine filaments that appeared to be attached to the surface of microfibrils. The filaments extended outward singly or formed loose aggregates. Their diameter ranged from 1.2 to 3 nm, with a mean of 1.5 nm. Because of their similarity to the fibronectin molecules previously described after rotary shadowing, the filaments were likely to be fibronectin molecules themselves. Since fibronectin is known to have high affinity for the amyloid P component, a model is presented in which fibronectin filaments are bound to the amyloid P component making up the tubular core of microfibrils in mice. Evidence is presented that fibronectin filaments may link microfibrils to one another and thus insure the continuity and strength of zonular fibers. More generally, it is likely that connective-tissue microfibrils, whether or not inserted into elastic fibers, are bonded through fibronectin to surrounding cells, collagen fibrils, or proteoglycans, and thus insure cohesion among connective tissue elements.

Actin Cytoskeleton↗
PubMed1989

51Cr-EDTA: a marker of early intestinal rejection in the rat.

Intestinal permeability was studied after accessory intestinal transplantation in Lewis rats. Five groups were evaluated: Group 1--isografts (N = 6); Group 2--Lewis X Brown Norway F1 (LBN-F1) allografts (N = 6); Group 3--isografts treated with CsA 2 mg/kg/day X 10 days (N = 6); Group 4--LBN-F1 allografts treated with CsA 2 mg/kg/day X 10 days (N = 6); Group 5--LBN-F1 allografts treated with CsA 4 mg/kg/day X 28 days (N = 6). Chromium-labeled ethylenedimianetetraacetate (51Cr-EDTA) was given through the proximal stoma of the graft. Renal clearance of 51Cr-EDTA and mucosal biopsies were followed post-transplant. The biopsies of the intestinal graft showed no rejection in Groups 1, 3, and 5; fulminant rejection in Group 2; and mild atypical rejection in Group 4. 51Cr-EDTA clearance was elevated in all groups during the first 7 days post-transplant. Thereafter, 51Cr-EDTA excretion fell to lower levels in the animals with histologically normal grafts (Groups 1, 3, and 5). 51Cr-EDTA excretion in Group 4 was increased with the first histological evidence of rejection on Day 14 and remained elevated until sacrifice (P less than 0.02 compared to Groups 3 and 5). A transient permeability defect occurs after intestinal grafting. Once the graft has recovered from this injury, 51Cr-EDTA is a sensitive marker for intestinal rejection.

Administration, Oral↗
PubMed1989

Chronic toxicity of sodium nitrite in the male F344 rat.

A long-term feeding study was carried out in rats with sodium nitrite. The test substance was administered as part of a reduced-protein diet to groups of 50, 6-wk-old, male F344 rats at dose levels of 0.2 or 0.5% (w/w) sodium nitrite for up to 115 wk. A control group of 20 males received the reduced-protein diet alone. Throughout the study, there was a dose-related decrease in the rates of body-weight gains and a corresponding decrease in body weights among animals fed sodium nitrite in the diet. Food intakes of rats in the low-dose group were slightly raised over most of the study. In the high-dose group, food intakes were reduced during the first month, but thereafter were similar to those of the control group. This reduction in food intake together with the lower body weights in the nitrite-treated animals, may indicate a reduction in food utilization. In the first week of treatment the following haematological parameters were reduced: red blood cell count, haematocrit and haemoglobin concentration. The red blood cell count continued to fall for 8 wk, then slowly returned to normal by wk 52. A dose-related reduction was noted in both the incidence and time of onset of lymphomas, leukaemias and testicular interstitial cell tumours. Leukaemias were only found in animals with lymphoma, indicating an association between the two lesions. Under the conditions described in this study, sodium nitrite was found not to be carcinogenic when fed to rats in the diet for up to 115 wk, but rather that the incidence of tumours was reduced in a dose-related manner, which correlated with a similar trend in body weights.

Animals↗
PubMed1989

A comparison of the antioxidant requirements of proteins with those of synthetic polymers suggests an antioxidant function for clusters of aromatic and bivalent sulphur-containing amino acid residues.

Many proteins which function in extracellular environments potentially rich in oxygen-derived free radicals contain clustered tyrosine and cysteine residues which, by analogy with the chemistry of antioxidants used with synthetic polymers, may provide an appreciable antioxidant and redox stabilization activity. Such proteins may function as antioxidants, and as ligand binding sites for free radicals and other active molecules employed in normal biochemical processes.

Antioxidants↗