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Biomedical subjects

P J Lawrence

Publications and source records attributed to P J Lawrence.

At least 19 recordsLinked to original sources
PubMed1986

Immobilization hypercalcaemia due to low bone formation and responding to intravenous sodium sulphate.

A young man developed acute renal failure and hypercalcaemia following severe burns. The hypercalcaemia was initially controlled by haemodialysis, but it persisted after return of renal function. Plasma PTH was inappropriately elevated, but the nephrogenous cyclic adenosine monophosphate level was low; thus the PTH was probably not biologically active, and may have been artefactually elevated by the moderate renal impairment. Bone histology, showed a normal resorbing surface, but a zero forming surface, implying that the bone dissolution leading to hypercalcaemia resulted from a failure of bone formation. Because of widespread infection and impaired renal function, the hypercalcaemia could not be treated by corticosteroid drugs, mithramycin or phosphate, and there was no response to salmon calcitonin. He was therefore treated with intravenous sodium sulphate, which increased urinary calcium excretion and reduced the plasma calcium. Sodium sulphate still has a role in the treatment of patients with hypercalcaemia.

Adult↗
PubMed1985

Ventilation during cardiopulmonary resuscitation: which method?

A questionnaire was circulated to assess the influence of the presence of vomitus, secretions and infection on the willingness of 70 hospital staff members to use methods of ventilation during cardiopulmonary resuscitation (CPR). The responses showed that only 13% would use mouth-to-mouth and 59% mouth-to-mask ventilation in the presence of these features. Thirty-five of these subjects were then tested for their ability to ventilate a manikin adequately (tidal volume, 800 mL). The best performance was seen with mouth-to-mouth ventilation. After instruction, their performance was satisfactory with mouth-to-mouth and mouth-to-mask resuscitation and with the Robertshaw resuscitator. Bag-valve-mask ventilation had a 97% failure rate before and after instruction and may be inappropriate for CPR. A resuscitation mask which allows effective ventilation without contamination and with oxygen supplementation is the most cost-effective and best accepted method of emergency ventilation.

Attitude of Health Personnel↗
PubMed1980

Coronary ostial stenosis in Takayasu's arteritis.

A patient with Takayasu's arteritis with left coronary ostial narrowing is presented. The dramatic clinical and pathologic findings are discussed in detail. Emphasis is placed on making the diagnosis as soon as possible, in order to expedite bypass surgery to prolong life.

Aortic Arch Syndromes↗
PubMed1979

Effect of cephapirin on formation of D-alanine carboxypeptidase in growing Bacillus subtilis cells.

Cephapirin was utilized to examine the interaction of beta-lactam antibiotics with growing Bacillus subtilis cells and the biological effects simultaneously produced. Saturation binding and quantitative cell death were observed at the cephapirin concentration of 0.1 mug/ml. Cephapirin bound to all penicillin-binding proteins except the d-alanine carboxypeptidase. A specific [(14)C]benzylpenicillin-binding assay was developed for the d-alanine carboxypeptidase. At the lowest saturating concentration of antibiotic (0.1 mug/ml), cephapirin inhibited formation of the d-alanine carboxypeptidase. Upon incubation with cephapirin, 18% of the membranous d-alanine carboxypeptidase was released into the media. The data suggest that beta-lactam antibiotics may affect the formation of bacterial cytoplasmic membranes in addition to their effect on cell wall synthesis.

Bacillus subtilis↗
PubMed1975

The formation of functional penicillin-binding proteins.

A method was developed which permitted determination of the [14C]benzylpenicillin and [14C]Cephapirin binding capacity of rapidly growing Bacillus subtilis cells in liquid culture. Over the concentration range of the binding plateau (0.1 to 0.8 mug/ml), [14C]benzylpenicillin significantly inhibited formation of functional penicillin-binding proteins, but had comparatively little effect on total bacterial protein synthesis. The data suggest that penicillin covalently bound to the cells in a chemically stable manner alone is not sufficient to inhibit formation of functional binding proteins and that unbound penicillin in the growth medium is necessary. The concentration of unbound antibiotic in the culture medium, in turn, is a function of the cell-bound penicillinase activity whose significance increases with cell density. [14C]Cephapirin, a cephalosporin resistant to this cell-bound penicillinase almost completely inhibited the formation of functional Cephapirin-binding proteins, but had relatively little effect on total protein synthesis. At concentrations 250-fold higher than that required to inhibit formation of functional binding proteins. Cephapirin did not inhibit particulate D-alanine carboxypeptidase activity and presumably did not bind covalently to this penicillin-binding protein.

Alanine↗
PubMed1975

Accessibility of the (14C)benzylpenicillin binding proteins in membranes of sporulating bacilli.

Triton X-100 treatment or freeze-thawing damages the membranes of sporulating or vegetative cells as seen by protein leakage from cells. A 40% increase in the specific [(14)C]benzylpenicillin-binding capacity of detergent-treated or frozen sporulating cells was observed. Neither freezing nor Triton X-100 treatment of vegetative cells produced a detectable effect on their [(14)C]benzylpenicillin-binding capacity. These data indicate the presence of penicillin-binding sites in intact sporulating bacilli not accessible to penicillin in routine binding assays. The chemical specificity of [(14)C]benzylpenicillin binding to detergent-treated sporulating cells is similar to that observed with untreated vegetative or sporulating cells.

Bacillus megaterium↗
PubMed1974

Penicillin: reversible inhibition of forespore septum development in Bacillus megaterium cells.

Benzylpenicillin inhibits the development of the forespore septum in sporulating Bacillus megaterium cells. The inhibitory effect is a function of the duration of exposure to the antibiotic and is completely reversible by penicillinase. Under the incubation conditions employed, less than 20% of the covalently bound antibiotic is released from the cells. The penicillin which remains bound to the cells after treatment with penicillinase may be necessary but is not sufficient for the effect; unbound antibiotic in the sporulation medium is also required.

Bacillus megaterium↗
PubMed1973

Binding of radioactive benzylpenicillin to asporogenous mutants of Bacillus subtilis during postexponential growth.

The specific penicillin binding capacity of a postexponential culture of Staphylococcus aureus remains constant, but that of a sporulating Bacillus subtilis culture fluctuates dramatically. An initial decrease in binding capacity during presporulation events is followed by two distinct intervals of enhanced specific binding capacity during the postlogarithmic growth of a sporulating B. subtilis culture. The first peak of enhanced binding occurs during septation, when enzymes for germ cell wall formation are present; and the second peak coincides with cortical biosynthesis. The specific postlogarithmic binding capacities of a number of Spo(-) mutants of B. subtilis were examined to ascertain if specific asporogenous mutations altered the binding pattern observed with the wild-type organism. Four distinct postexponential binding patterns were recognized: (i) a low, constant binding capacity resembling the binding pattern of S. aureus, (ii) a decrease in binding capacity with no subsequent significant peaks, (iii) a decrease in binding capacity followed by a single peak corresponding to the first peak seen with the wild type, (iv) a pattern similar to the wild type. The fourth pattern was observed in a mutant blocked during stage III of sporogenesis which produced forespores that never became refractile. Mutations blocking either one or both periods of enhanced postlogarithmic binding were interspersed throughout a linkage group of spore genes next to lys-2 on the B. subtilis chomosome.

Bacillus subtilis↗
PubMed1971

Binding of radioactive benzylpenicillin to sporulating Bacillus cultures: chemistry and fluctuations in specific binding capacity.

The chemistry of the binding of (14)C-benzylpenicillin to sporulating cultures of Bacillus megaterium and B. subtilis is similar to that in a 4-hr vegetative culture of Staphylococcus aureus. Unlabeled penicillins prevent the binding of (14)C-benzylpenicillin, but benzylpenicilloic acid and benzylpenilloic acid do not. Bound antibiotic can be removed from cells with neutral hydroxylamine at 25 C. Sporulating cultures display two intervals of enhanced binding, whereas binding to stationaryphase S. aureus cells remains constant. The first period of increased binding activity occurs during formation of the spore septum or cell wall primordium development, and the second coincides with cortex biosynthesis.

Bacillus↗