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Biomedical subjects

J Lawson

Publications and source records attributed to J Lawson.

At least 109 records · Page 6Linked to original sources
PubMed1978

Antigens in urine of patients with glomerulonephritis and in normal human serum which cross-react with group A streptococci: identification and partial characterization.

Hyperimmune rabbit antisera antisera against group A streptococci precipitate protein antigens present in the urines of patients with poststreptococcal AGN and other glomerulopathies and also present in normal human serum. Over 90% of patients with AGN excrete detectable amounts of cross-reactive antigens in their urines, as do approximately 20% of patients with nonstreptococcal glomerulopathies. The streptococcal antigens are present in culture supernates, and immunodiffusion reactions in agar gel show identity or partial identity of serum, urine, and streptococcal antigens with antisera prepared against either urine proteins or against whole group A streptococci. Cross-reactive antibodies are removed from rabbit antisera by absorption with streptococcal culture supernates but not by absorption with a variety of streptococcal somatic constituents. The cross-reactive antigens have been isolated from streptococcal cultures grown in synthetic medium, thus eliminating the possibility of artefact due to tissue antigens present in Todd-Hewitt broth. The principal antigens have now been purified both from AGN urine and streptococcal supernates by molecular sieve and ion-exchange chromatography. They both have a molecular weight of approximately 360,000 daltons, as estimated on columns of agarose. The urine antigen has been applied to SDS-PAGE, and the migration of the major band was consistent with a molecular weight of 85,000 daltons. Rabbit antiserum to purified urine antigen precipitates both AGN urine and streptococcal supernates. These newly recognized human antigens, which cross-react with group A streptococcal antigens, are of particular interest because of their presence in readily available biologic fluids and their preferential excretion in almost all patients with poststreptococcal AGN.

Antigens, Bacterial↗
PubMed1977

Treatment of vulvovaginal candidiasis in pregnancy. A comparative study.

A carefully controlled comparative study showed miconazole nitrate 2% vaginal cream (Monistat) to be a highly effective agent in the treatment of vaginal candidiasis in pregnant subjects. Miconazole nitrate was significantly more effective than nystatin (Mycostatin) in the treatment of vaginal candidiasis in all three trimesters of pregnancy, and also more effective regardless of whether the candidal infection was primary or recurrent. Observations relating to the safety of this therapy during pregnancy were made and discussed.

Acute Disease↗
PubMed1976

The effect of oral contraceptives on plasma cortisol and cortisol binding capacity throughout the menstrual cycle in normal women.

Plasma cortisol and cortisol binding capacity (CBC) was measured throughout the menstrual cycle in 25 healthy women aged between 20 and 35 years. Ten women were taking an oral contraceptive containing 50 mug oestrogen and progestogen ("combined pill"), one patient took a progestogen-only contraceptive and 14 served as controls. Despite the low oestrogen content of the combined pill the level of plasma cortison and CBC were signifcantly higher than in controls at all stages of the cycle, and the cortisol/CBC ratio greater than unity during most of it. Levels in the women taking a progestogen-only contraceptive were indistinguishable from controls. The plasma cortisol and CBC levels were significantly higher in the last week of the cycle than in the first in the combined pill group, but there was no significant variation in the controls.

Adult↗
PubMed1976

A three-month survival of a calf with an artificial heart.

An artificial heart constructed from Biomer, a polyurethane, kept a calf alive for more than three months after its natural heart was removed. During this time all of the calf's vital organs apparently functioned well. We had been able to keep similar animals alive with Jarvik III hearts made from Silastic for one month. The principal problem encountered was the infection centering along the compressed air drive lines to the artificial heart. Another problem is thrombus formation in the artificial heart. Redesigning of the artificial ventricles to improve flow patterns and reduce material discontinuities should be attempted to eliminate localized thrombus formation within the ventricles. The rapid growth of the calf has led us to examine the possibility of alternative animal models for future long-term experiments. The most encouraging aspects of this experiment were the long survival time of the calf and the very low level of blood damage caused by the artificial heart.

Alkaline Phosphatase↗
PubMed1976

Saving the aortic and pulmonary artery valves with total heart replacement.

The natural aortic and pulmonary artery valves can be saved with excision of the ventricles and inflow valves. These valves remain functional and unaltered with implantation of an artificial heart, when pumped for 96 and 122 days. The capacity of the artificial heart to meet the physiological needs of the animal, during exercise and body growth, over 3 and 4 mos has been documented. All of the parameters monitored in 2 experiments for 3 mos (and continuing) and 4 mos clearly demonstrates the efficacy of meeting the cardiac needs with an artificial heart.

Animals↗
PubMed1975

The growth of the pollen tube wall in Oenothera organensis.

The growth of the pollen tube wall of Oenothera is effected by the expulsion of fibrillar material from the cytoplasm into the developing wall. This material may also be seen in the cytoplasm, contained in membrane-bound vesicles. It is not clear how the content of the vesicles is discharged, but it appears not to involve the participation of microtubules. The source of the cytoplasmic fibrillar bodies depends upon the stage of development of the pollen tube. The earilest growth is derived from the inclusion into the wall of vesicles containing pre-formed materials present in the grain on pollination. During the next stage of growth the wall is derived from the content of double-membraned inclusions also present in the pollen. The content of the former vesicles is not so similar to the wall as the latter, but intermediates between the 2 types of vesicle may be seen in the cytoplasm, indicating that the former are formed from the latter. Most of the tube wall is derived from the products of dictyosomes in the pollen grain or tube. These dicytosomes are few in number and they must be exceedingly active. This, and the observation that dictyosome vesicles are frequently associated with banked complexes of mitochondria, indicates that some steps in the metabolism of the vesicular content, perhaps phosphorylation, take place distant from the dicytosomes. These different sources of fibrillar material presumably permit the rapid starting of tube growth, without any attendant metabolism. However, it would be impossible to include enough pre-formed wall material in the grain to enable the full growth of the tube, so once started, it seems that the tube then relies on the elaboration of simple reserves for the contruction of its wall. These reserves are likely to be held in the pollen, and may be the large numbers of starch grains characteristic of the pollen cytoplasm.

Cell Wall↗
PubMed1975

Thrombus generation within the artificial heart.

The sites of thrombus formation in the Jarvik III artificial heart were studied in 20 consecutive calf experiments. Identical design and implantation procedures were used with two different surfaces. The 10 anticoagulated calves receiving Dacron-fibrilized silicone rubber surfaces survived an average of 296 hours. In contrast, the 10 nonanticoagulated calves with smooth poyurethane hearts survived 545 hours. The polyurethane surfaces were constantly clean. However, the rough surfaces were coated with variable amounts of thrombi. The sharp angle between the diaphragm and housing contained varying amounts of thrombi deposits in 75 per cent of the cases. Thrombe deposition occurred on 41 per cent of the valves. These thrombe were the source of emboli into the kidney, brain, and lungs. Turbulences and stagnation areas generated thrombus formation. Anticoagulation did not prevent thrombus formation. It would appear that heart free of turbulence and stagnation areas must be designed to eliminate thromboembolism.

Animals↗