Search PubMed⌕ Search

Biomedical subjects

P Patel

Publications and source records attributed to P Patel.

At least 253 records · Page 14Linked to original sources
PubMed1985

Polyunsaturated fatty acids and diabetic retinopathy.

One hundred and forty nine diabetic patients were ophthalmologically assessed seven years after randomisation to a low carbohydrate or modified fat diet (rich in linoleic acid). Glycaemic control, regardless of the type of diet, was a major determinant of the development of retinopathy. Poorly controlled patients (haemoglobin A1c greater than 8%) with low levels of linoleic acid in cholesterol ester had a significantly greater frequency of retinopathy than well controlled patients or patients with similarly unsatisfactory control but higher levels of linoleic acid. The findings support an earlier suggestion that linoleic acid might protect against diabetic retinopathy.

Cholesterol Esters↗
PubMed1984

Differential methylation of hypoxanthine phosphoribosyltransferase genes on active and inactive human X chromosomes.

Previous theoretical considerations and some experimental data have suggested a role for DNA methylation in the maintenance of mammalian X chromosome inactivation. The isolation of specific X-encoded sequences makes it possible to investigate this hypothesis directly. We have used cloned fragments of the human hypoxanthine phosphoribosyltransferase (HPRT) gene and methylation-sensitive restriction enzymes to study methylation patterns in genomic DNA of individuals with different numbers of X chromosomes and in somatic cell hybrid lines containing human X chromosomes that are either active or inactive or have been reactivated by treatment with 5-azacytidine. The results of these analyses show that there is hypomethylation of active X chromosomes relative to inactive X chromosomes in the 5' region of this gene. In the middle region of the gene, however, a site that is consistently undermethylated on inactive X chromosomes was identified. Taken together, the data suggest that the overall pattern of methylation, rather than methylation of specific sites, plays a role in the maintenance of X chromosome inactivation.

Base Sequence↗
PubMed1984

A comparison of isocaloric high carbohydrate and high fat test meals in diabetics.

Ten diabetic patients were given test meals at breakfast and lunch on successive days to compare the acute glycaemic responses to meals either high (65%) (HC) or extremely low (12%) in carbohydrate; the latter was very high (71%) in fat (HF). The meals were isocaloric and fibre content, though higher in HC, was within the range of the average British intake for both diets. The mean fasting blood glucose levels were similar on the 2 days (9.8 mmol/l; 9.6 mmol/l) but mean peak post-prandial levels were significantly greater after the HC meals (17.7 mmol/l after breakfast and 14.1 mmol/l after lunch) than after the HF meals (11.7 mmol/litre after breakfast; P less than 0.02; 8.1 mmol/l after lunch; P less than 0.02). Mean blood glucose value for the 6-hr study period was significantly higher after the HC meals (14.0 mmol/l) than after the HF meals (9.2 mmol/l; P less than 0.001). There was no significant difference in mean fasting, peak or total mean triglyceride level. In the short term, therefore, meals very low in carbohydrate and high in fat are followed by a lower glycaemic response than meals high in carbohydrate but with only a usual (22 g/day) fibre content. Delayed gastric emptying after HF meals may well contribute to the results but long-term use of such HF meals is not advised in view of the extremely high fat content.

Blood Glucose↗
PubMed1984

Dense cells in sickle cell anemia: the effects of gene interaction.

In an attempt to uncover potential genetic sources of the clinical diversity of sickle cell anemia, we have characterized homozygous SS patients in the following ways: percentage of dense red blood cells (% F4) as determined from Percoll-Stractan continuous density gradients, alpha gene deletion, average percentage of hemoglobin F (% HbF), hemoglobin in g/dL, age, and sex. We find that alpha 4 individuals have a higher % F4 (mean 24% +/- 15%) than alpha 3 individuals (mean 12% +/- 8%) (P less than .005). Multivariate analysis demonstrated a significant correlation among % F4 levels and alpha-gene number and % HbF, and an interaction between the last two variables. The other variables considered did not significantly alter this model. As reported before, with fewer samples, we find that in the first ten years of life of SS individuals, the frequency of alpha gene deletion is 17%, which is comparable to that in the general black population, while in the group over 20 years of age, the frequency rises to 49%, implying that alpha thalassemia is associated with longer survival. These results indicate that it is necessary to consider sickle cell anemia not only as a single gene defect, but also as a disease whose clinical expression is the result of a group of genes capable of interacting at the phenotypic level.

Adult↗
PubMed1984

IgG-protein A complexes modulate thymidine incorporation into DNA of antibody and complement-stimulated cells.

Incubation of protein A (PA) and molar excess of whole rabbit immune IgG in solution favored the formation of high m.w. complexes with the molecular formula of [(IgG)2(PA)]2, which enhanced the incorporation of [3H]thymidine ([3H]dThd) into DNA of L cells, especially in the presence of rabbit or human complement (C). In contrast, complexes with the molecular formula (IgG)(PA), formed by incubation of IgG with molar excess of PA, failed to enhance, or inhibited, the incorporation of [3H]dThd into cells treated with immune IgG alone or with C present, respectively. Concanavalin A (Con A), which is known to bind to critical exposed oligosaccharide structures present in the Fc region of IgG in the [(IgG)2(PA)]2 complexes, reversed the enhancement of [3H]dThd incorporation, and alpha-methyl mannoside, but not D-galactose, inhibited the Con A reversal. The [(IgG)2(PA)]2 complexes efficiently activated the C cascade, caused significantly higher levels of aggregation of cells, and increased the binding of immune IgG to the cells when compared to the (IgG)(PA) complexes. Both types of complexes, isolated by sucrose density ultracentrifugation, were precipitable in a radioimmunoassay with chicken anti-PA antibodies and were capable of binding to intact L cells.

Agglutination↗
PubMed1983

Identification of mammalian DNA repair factors using a reconstituted subcellular system. Partial characterization and subcellular location of a DNA repair-stimulating protein in hamster cells.

By reconstituting lysolecithin-permeabilized hamster cells with endogenous proteins, a protein(s) which stimulated bleomycin-induced DNA repair synthesis was identified. The repair protein was inactivated by proteinase K and had an apparent molecular weight of 12 000-15 000 D. The following enzymatic activities were not detected in the partially purified DNA repair protein: general endonuclease, apurinic endonuclease, exonuclease, DNA polymerase or DNA polymerase beta-stimulating activity. The subcellular location of the DNA repair-stimulating activity was investigated by cytochalasin B enucleation; approx. 80% of the activity was associated with karyoplasts, suggesting a nuclear location. Neither the activity nor subcellular location of the repair protein fluctuated appreciably during the cell cycle, consistent with a physiological role in DNA repair. Although the function of the DNA repair protein is not yet known, this approach should be useful in identifying and characterizing mammalian DNA repair proteins.

Animals↗
PubMed1983

Increased bone metabolism in rheumatoid arthritis as measured by the whole-body retention of 99Tcm methylene diphosphonate.

Bone metabolism in 21 patients with rheumatoid disease was investigated by measurement of the 24-hour whole body retention (WBR) of 99Tcm methylene diphosphonate (MDP) in parallel with clinical, radiological, and biochemical measurements (urinary excretion of hydroxyproline) of disease activity. Corticosteroid-treated patients of those with other forms of metabolic bone disease were excluded from the study. WBR was increased in the rheumatoid patients as compared with 21 age- and sex-matched controls (p less than 0.05), and there was a significant correlation in the rheumatoid group between WBR and urinary excretion of hydroxyproline (p less than 0.01) and between urinary excretion of hydroxyproline and an articular index (p less than 0.05) and global index (p less than 0.01) of disease activity. The increased WBR of the rheumatoid patients was not explicable by factors such as immobilisation, and the results are interpreted as reflecting an overall increase in bone metabolism which may occur in rheumatoid arthritis as part of the disease process.

Adult↗
PubMed1981

Epstein-Barr virus (EBV)-lymphoid cell interactions. I. Quantification of EBV particles required for the membrane immunofluorescence assay and the comparative expression of EBV receptors on different human B, T and null cell lines.

We report data on the number of Epstein-Barr virus (EBV) particles required to detect virus binding to target cells (Raji or BJA-B) by means of membrane immunofluorescence (MIF). After determining the optimum conditions for the MIF assay the following aspects of EBV-lymphoid cell interactions were examined: (i) binding of two different strains of EBV to various types of human lymphoid cell lines, (ii) expression of receptors for both EBV and complement on these lines and (iii) induction of EBV-induced nuclear antigen (EBNA) in the different target cells used. The results showed that a minimum of about 2.7 x 10(3) enveloped virus particles/cell were required for an optimum visualization of EBV binding to the target cells tested, and that a lymphoid cell may bear receptors for one prototype strain of EBV but not for the other. A number of cell lines, particularly those of T and null type which express EBV receptors, did not synthesize EBNA, thus indicating that these lines were resistant to EBV infection. Several of these lines, although expressing cell surface EBV receptors, lacked complement receptors.

Antigens, Viral↗
PubMed1978

Drug therapy in intermittent claudication: an objective assessment of the effects of three drugs on patients with intermittent claudication.

It has been suggested that, by reducing the viscosity of blood, flow through capillaries is increased with consequent improvement in the symptoms of patients with peripheral vascular disease. We examined the effects of treatment with drugs purported to reduce blood viscosity to test the validity of this claim. Measurements of viscosity and the rate of blood flow to the leg were made in a group of patients before and after treatment with three different drugs--tetranicotinoylfructose (Bradilan), oxypentifylline (Trental) and cinnarizine (Stugeron). All patients had intermittent claudication in one leg and the distribution of arteriosclerosis was similar in each patient. After treatment there was little or no change in blood viscosity and no change in the rate of flow recorded in the symptomatic legs. We did not find any objective evidence to support the use of these drugs in patients with intermittent claudication.

Aged↗
PubMed1978

Age related differences in cellular immune response to vaccine induced rubella infection.

Employing the techniques of in-vitro lymphocyte transformation (LTF) and using Putnam strain of rubella virus as the antigen, the development of rubella specific cellular immune response was studied in different age groups of rubella seronegative normal subjects at various intervals after subcutaneous administration of HPV=77/DE5 live attenuated rubella vaccine. The rubella specific lymphocyte response in children ranging in age from two to twelve years was characterized by significant LTF activity at two months, followed by a gradual decrease. The response in adult subjects 18 to 35 years of age showed a slight delay initially in the appearance and the maximum LTF activity appeared to be 3--4 fold lower (P less than 0.01) than observed in the children. No difference was observed in the maximum antibody titers to rubella virus between these two groups of subjects. These observations suggest that the age related differences in the lymphoproliferative responses might be associated with adverse effects which are known to occur more frequently in adolescent and older patients than in childhood population after vaccine induced rubella infection.

Adolescent↗