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Biomedical subjects

A Knight

Publications and source records attributed to A Knight.

At least 91 records · Page 5Linked to original sources
PubMed1982

The purification of gametocytes of Plasmodium falciparum and P. yoelii nigeriensis by colloidal silica (Percoll) gradient centrifugation.

Percoll gradient centrifugation has been applied to Plasmodium falciparum- and P. yoelii-infected blood to allow rapid concentration of gametocytes. In the case of cultured P. falciparum, stage IV and V gametocytes were separated from immature stage II and III forms and concentrated from initial gametocytaemias of 1 to 3% to an average of greater than 80% and a maximum of 100% purity in a fraction which collected at the 1.064/1.083 g/ml interface; the rounded gametocytes of P. yoelii-infected mouse blood were also concentrated in this fraction. A much larger enrichment in microgametocyte concentration (average of 160-fold) was recorded in a fraction that collected at the 1.047/1.064 g/ml interface. The large increases in gametocyte concentration were paralleled by similarly large increases in exflagellation activity, thus confirming the viability of both preparations.

Centrifugation, Density Gradient↗
PubMed1981

Extracorporeal perfusion of the whole human placenta--a new model.

An extracorporeal dual perfusion system of the whole human placenta was developed using a technique of multiple blunt cannulations of the intervillous space. The system was evaluated according to various perfusion-dynamic, metabolic and morphological criteria. Angiographic and dye distribution studies showed 80 to 100 per cent perfusion of the placenta. The perfused organ consumed oxygen, utilized glucose and produced HCG. The flow rates and acid-base values were within acceptable limits. However, problems with high fetoplacental vascular resistance, tendency to metabolic acidosis and fetomaternal fluid transfer were encountered. Ultrastructural studies showed variations in the syncytiotrophoblast and the microvilli.

Acid-Base Equilibrium↗
PubMed1980

Autoantibodies with intrinsic biological activity.

Thyroid-stimulating autoantibodies (TSaab) react with the thyrotrophin receptor of the thyroid cells to cause the hyperthyroidism of Graves' disease. Studies using thyroid receptors from various animal species have demonstrated the existence of a fine variation in the specificity of TSaab from various patients. Such variation provides an explanation for the clinical variety seen in some autoimmune diseases and also for the occurrence of inconstant complications such as exophthalmos, chorea, diabetic retinopathy and diabetic nephropathy, which may be based on cross-tissue reactivity.

Animals↗
PubMed1979

Immunological parameters in perennial rhinitis.

As part of a study of the effectiveness of beclomethasone dipropionate in perennial rhinitis five immunologically related parameters were measured. These included skin tests, total IgE, specific IgE, nasal and peripheral blood eosinophil counts. In addition, nasal biopsies were obtained in twenty out of sixty patients. It was apparent that patients with perennial rhinitis formed a heterogeneous group who could be divided into three groups based on the extent of immunological abnormality detected. Group 1 consisted of twenty patients who displayed no abnormality in any of the five parameters studied. Group 2 consisted of twenty-six patients in whom specific IgE was not detected but who had varying degrees of abnormal findings in the other laboratory parameters. The remaining fourteen patients formed a third group in whom specific IgE was detected in addition to abnormalities in other parameters. In general, patients with detectable specific IgE had a higher frequency of abnormal parameters, including abnormal histology of their nasal biopsy, than patients in whom no specific IgE was detected. The heterogeneous nature of perennial rhinitis is discussed. Despite the heterogeneous nature of the total patient group, the majority of patients (80%) treated with beclomethasone dipropionate improved compared to 20% improved in the placebo group. There was no difference in the drug effect between the three groups of patients.

Adolescent↗
PubMed1977

Is there a relationship between lupus erythematosus and lichen planus?

Three patients showing features of both lupus erythematosus and lichen planus are described together with their histological, immunofluorescence and other investigative findings. The similarities between lupus erythematosus and lichen planus are discussed and it is suggested that these may be the result of common pathophysiological pathways.

Adult↗
PubMed1976

Disodium cromoglycate in ragweed-allergic rhinitis.

This study was designed to test the effectiveness of disodium cromoglycate when compared to placebo in a double-blind study in patients with ragweed allergic rhinitis. Patients were selected on the basis of a clinical history and a 4+ reaction to the intradermal injection of water-soluble ragweed, 0.02 c.c. of 500 PNU/c.c. Active agent/placebo groups were selected at random and were on the drug for approximately 8 wk, commencing 1 wk prior to the onset of the ragweed pollen season. Patient response was evaluated using patient diary cards, number of antihistamine tablets taken, and patient interviews. In the Toronto study, of 17 patients on the active drug, 15 were graded as improved, compared to only 6 of 21 placebo-treated patients who were improved. However, in the Hamilton study, results were less impressive. Nonetheless, it appears that intranasal insufflation of disodium cromoglycate was more effective in reducing ragweed hay fever symptoms than placebo.

Clinical Trials as Topic↗
PubMed1976

The relative paucity of IgE in human milk.

The levels of IgE were determined in paired samples of serum and milk when whey obtained 3 to 8 days of postpartum, from 16 human lactating mothers who had reported a history of allergy to a variety of common allergens. Two assay procedures were employed to measure total IgE, a double-antibody assay and a commercially available solid phase assay (RIST). In addition, each sample of serum and whey was tested for specific IgE antibodies to a variety of allergens by the RAST test. The levels of total serum IgE were between 30 and 2300 I.U./ml and relatively good agreement was observed for both the double-antibody and RIST methods. In contrast, total IgE levels in milk whey were either undetectable (less than 3.0 I.U./ml in 14 of 16 subjects) or very low when analyzed by the double-antibody method, but were very high (400 to 1650 I.U./ml when analyzed by the RIST method. However, IgE added to milk whey could be measured by the double-antibody procedure indicating that the low levels detected in milk were not a fault of the double-antibody assay. It was assumed that the RIST test was subject to nonspecific interference by factors in milk whey which caused the determination of high, but incorrect, levels of IgE. Specific IgE antibodies were detected in the serum of 10 of 16 subjects but were not present in milk whey. A comparison of the whey/serum ratios of albumin, IgA, and IgE suggested that little, if any, IgE is selectively synthesized or secreted in the mammary gland.

Animals↗
PubMed1974

Ammonium chloride poisoning in chronic renal disease.

A 58-year-old woman with a long history of renal stone disease and urinary tract infection presented to the emergency room with exhaustion and air hunger. Laboratory data confirmed profound metabolic acidosis. Unduly large quantities of bicarbonate and potassium were required for correction of the deficits. She had been taking 6 g daily of ammonium chloride as a urine-acidifying agent for a period of six months in addition to agents directed against urinary tract infection. The combination of impaired renal function and effective hydrogen ion loading resulted in profound systemic acidosis. The metabolic derangements associated with the administration of ammonium chloride and its use as a therapeutic agent are discussed.

Acidosis↗