Biomedical subjects
Publications and source records attributed to M Johnson.
We have reviewed 66 cases of antibiotic-associated colitis since March 1975, which have been associated with a 27 per cent mortality. We believe antibiotics may predispose patients to this condition which is caused by a toxin produced by Clostridium difficile. Although the disease is rare, it is more common than previously reported. The presentation, methods of diagnosis and treatment are discussed.
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Various tubular functions were assessed in 10 patients with polycystic kidney disease (PKD). Three relatively unique abnormalities were apparent in many of these patients -- an inability to maximally concentrate urine, a decrease in ability to lower urine pH after acute acid challenge, and an inability to excrete adequate amounts of ammonium during persistent acid challenge. The defects in urinary acidification and ammonium excretion in PKD have not been previously described.
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The efficacy of vancomycin in pseudomembranous colitis was assessed in a prospective randomised controlled trial. Forty-four patients with postoperative diarrhoea were allocated to five days' treatment with either 125 mg vancomycin six-hourly or a placebo. Sixteen patients had high titres of the neutralised faecal toxin characteristic of pseudomembranous colitis; nine received vancomycin and seven placebo. At the end of treatment faecal toxins were present in one patient given vancomycin compared with five of the controls. Vancomycin caused the disappearance of Clostridum difficile from the stool in all except one patient, whereas toxicogenic strains of Cl difficile persisted in all but one of the controls. Histological evidence of psuedomembranous colitis had disappeared by the end of treatment in six out of seven patients given vancomycin compared with only one out of seven patients given vancomycin compared with only one out of five patients given placebo. In patients with faecal toxins bowel habit had returned to normal in seven of the vancomycin group compared with only one of the controls, but there was no significant difference in clinical response among patients without faecaal toxins. The results suggest that vancomycin eliminates toxin-producing Cl difficile from the colon and is associated with rapid clinical and histological improvement in patients with pseudomembranous colitis.
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Arguments are presented for the hypothesis that during an early stage of development the cells which become principal neurons of the autonomic nervous system possess information regarding the positions they will occupy within the body. A second stage of development, during which a decision is made regarding which neurotransmitter to employ, is delayed until each neuron has assumed its permanent position in the body and has sampled, presumably via its growing axons, the peripheral field which it will innervate. The development of cholinergic mechanisms takes precedence; adrenergic neurons may develop only when cholinergic sites have been occupied. An extended period during which the differentiation of transmitter mechanisms may be modulated permits the neuron to adequately sample the periphery prior to commitment to a specific transmitter economy.
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A 17-year-old girl had intraocular pressure readings of 30 to 40 mm Hg in both eyes, with normal visual fields and optic nerve heads. Medical treatment was unsuccessful in lowering the IOP measurements substantially. The central corneal thickness was 0.90 mm in each eye in the absence of corneal edema. Cannulation of the left anterior chamber revealed an IOP of 11 mm Hg, while the Perkins' and Schiŏtz' tonometers gave readings of 35 and 34 mm Hg, respectively. Previously, elevated tonometry readings had been obtained by Goldmann's, Perkins', Schiŏtz', MacKay and Marg's, pneumatic tonometer and air puff tonometer. This suggested that measurement of central corneal thickness be performed in cases in which IOP recordings do not correspond to other clinical findings.
This study showed that scleral heterografts in the oral cavity work. Such grafts demonstrate the following characteristics: (1) attach firmly to submucosal, periosteal, and bony tissues; (2) remain firm and fibrotic in nature, indicating the possibility of a stressbearing tissue; (3) show little or no scarring or contracture; (4) show minimal, or no- host antigenic response based on clinical acceptance; (5) appear to become vascularized and cellular, blending with adjacent collagen. As projected by this study, scleral heterografts might well be used to obliterate bony undercuts and perhaps to obtund cystic cavities and other major bony defects. Further studies of layering of the sclera are essential before any definitive result can be determined in large bony defects. In those areas in which no bone regeneration would be feasible, such as in the mylohyoid region of the mandible, this application does present a possibility for removing undercuts as opposed to removing overlying bone. The tenacity of adherence to submucosal tissues, periosteum, and bone makes scleral heterografting even more intriguing in the possible obliteration of oroantral fistulas. We might theorize that the sclera would not only attach to the buccal and palatal flaps but also show a rather firm and tenacious adherence to the bony walls of the antral defect. The availability of human bank sclera for use as presently made by periodontists and as pioneered by Klingsberg is somewhat limited. From our study, an extrapolation would indicate that, because of the comparably low and antigenicity of bovine sclera and human sclera, an investigation in this area should be completed in order to determine whether scleral heterografts can replace scleral homografts in human periodontal surgery. Sclera is easily preserved in anhydrous glycerine (as preserved by King and associates19) and can certainly be stored in banks. In our opinion, the final application of scleral heterografts, human or bovine, the role of antigenicity, and the ability of osteoblasts to invade either a single piece or layers of sclera warrant further study.
A simple method is described for the determination of 13, 14-dihydro-15-keto-prostaglandin F2alpha (PGFM), using a highly specific antiserum raised in New Zealand rabbits. It involves extraction of human peripheral venous plasma with diethyl ether after addition of tritiated PGFM and HCl. Radioimmunoassay is performed on appropriate aliquots; after 2 hours or overnight equilibration the bound and free metabolite are separated using dextran-coated charcoal. The mean values +/- S.D. obtained are as follows: healthy males 32 +/- 16 pg/ml, females during follicular phase 48 +/- 18 pg/ml, luteal phase 37 +/- 8 pg/ml, first trimester of pregnancy 66 +/- 33 pg/ml, second trimester 67 +/- 42 pg/ml and third trimester 72 +/- 26 pg/ml.
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Plasma levels of progesterone, 17-hydroxyprogesterone and 20 alpha hydroxypregn-4-en-3-one were established from 4 to 16 weeks gestation by sampling 15 normal patients twice weekly. Apart from a peak at week 5, the mean levels of progesterone remained constant at about 24 ng/ml until week 10 and then rose progressively to 40 ng/ml at week 16.20 alpha hydroxypregn-4-en-3-one remained within the 7 to 9 ng/ml range apart from a peak at week 5. A significant decrease in mean levels of 17-hydroxy-progesterone was noted from week 5 to a nadir of 3 ng/ml at week 11. It would appear that the main hormone production of progesterones in pregnancy has been taken over by the placental unit by the 10th week.
Plasma progesterone, 17-hydroxyprogesterone, 20alpha hydroxypregn-4-en-3-one levels were determined twice weekly up to 16 weeks gestation, where possible, in a twin pregnancy, in two patients who aborted spontaneously and in three patients who were treated with 'progesterone supplements' because of abnormal vaginal cytology. There was no correlation between vaginal smears and the plasms hormone levels and there was no evidence to suggest that progesterone supplements influenced clinical outcome. Compared with normal mean values the only difference was a significantly rise in progesterone and 20alpha hydroxypregn-4-en-3-one levels in the twin pregnancy after the 12th week and a precipitate fall in all hormone levels just prior to abortion. Plasma hormone levels could not be used to predict outcome.
A case with the clinical appearance of WDHA syndrome is described in which serum concentrations of the newly recognized hormonal principle pancreatic polypeptide (PP) were highly elevated, while plasma levels of vasoactive intestinal peptide were within the normal range. The symptoms of the patient seem to be derived from the high levels of circulating PP, as illustrated by an improvement after resection of liver metastases accompanied by a marked decrease of serum PP concentration. Streptozotocin treatment was without effect upon the watery diarrhoea, and PP levels also remained unchanged during medical treatment. The appearance of a PP-secreting tumour leading to a clinical WDHA syndrome widens the spectrum of hormone assays that have to be performed in these patients.