Biomedical subjects
Publications and source records attributed to A Robin.
A recent case of posttraumatic splenic abscess in an HIV-positive intravenous drug abuser following a splenic salvage procedure is reported. With the recent trend toward splenic preservation and the ever-increasing population of HIV-positive, immune-compromised patients, the complication of splenic abscess may become more common.
Use of a diaphragmatic flap to buttress and help secure persistent intestinal fistula is described. The potential for the use of muscle flaps in the management of recurrent intestinal fistula is presented.
The kinetics of K+ efflux across the membranes of i) wild-type Escherichia coli poisoned by the thiol reagent N-ethylmaleimide, ii) K+ retention mutants and iii) glutathione-deficient mutants, have revealed a common "K+ leaky phenotype"; it is characterized by a very high rate of K+ efflux. The results suggest that the products of kefB and kefC genes could encode two K+ channels, both gated by glutathione. The possible function of these K+ channels seems to be a K+ exit controlled by the redox state of the cell; indeed, it can be inferred from the effects of several oxidants and reductants that turning on and off of the K+ efflux mediated by the channels can be correlated with the redox state of glutathione.
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The ftsZ gene of Escherichia coli, which lies in a cluster of cell division genes at 2 min on the genetic map, codes for a protein which is thought to play a key role in triggering cell division. Using an ftsZ::lacZ operon fusion, we have studied the transcription of the ftsZ gene under conditions in which cell division was either inhibited or synchronized in the bacterial population. In ftsZ, ftsA, ftsQ, and ftsI (or pbpB) mutants, there was no change in the differential rate of expression of the ftsZ gene in nonpermissive conditions, when cell division was completely blocked. Although the FtsZ protein is thought to be limiting for cell division, in synchronized cultures the ftsZ gene was expressed not only at the moment of septation initiation but throughout the cell cycle. Its expression, however, was not exponential but linear, with a rapid doubling in rate at a specific cell age; this age, about 20 min after division in a 60-min cycle, was different from the age at which the ftsZ::lacZ operon was duplicated. However, it was close to the age at which replication initiated and at which the rate of phospholipid synthesis doubled. During the transient division inhibition after a nutritional shift-up, ftsZ transcription again became linear, with two doublings in rate at intervals equal to the mass doubling time in the rich medium; it adopted the exponential rate typical of rich medium about 60 min after the shift-up, just before the bacterial population resumed cell division. The doubling in the rate of ftsZ transcription once per cycle in synchronized cultures and once per mass doubling time during the transition period after a nutritional shift-up reflects a new cell cycle event.
Of two groups of 20 patients accepted for gender reassignment surgery, one was offered early operation and therefore had had surgery by follow-up two years later, while the second was still awaiting operation at two-year follow-up. Although the groups were similar initially, significant differences between them emerged at follow-up in terms of neuroticism and social and sexual activity, with benefits being enjoyed by the operated group.
Because more than 60% of adolescent visits to physicians last less than 10 minutes, simple screening devices to identify persons at risk for social morbidity are needed. The result of a pilot screening instrument for depression and parent-teenager conflict is described. A seven-item questionnaire (three items for depression and four items for parent-teenager conflict), the Beck Depression Inventory (BDI), and the Conflict Behavior Questionnaire (CBQ), were administered to 226 adolescents at a high-risk adolescent heath center. After the visit, the provider rated each patient on a five-point Likert scale for level of depression and parent-teenager conflict. The screening questionnaire and the provider ratings were compared with the BDI and CBQ for sensitivity, specificity, and predictive value. A majority of the subjects (61% for depression and 63% for parent-teenager conflict) had no positive screening responses and, of these, less than 3% were classified as being depressed or having parent-teenager conflict by the BDI or CBQ. There were three or four positive screening responses (three responses for the depression questions and 20 responses for the parent-teenager conflict questions) among 23 adolescents and all of these scored in the abnormal range on the BDI or CBQ. Approximately one third of the subjects had intermediate responses. With one positive response, the predictive value for depression and parent-teenager conflict was 17% and 24%, respectively, whereas with two positive responses the predictive values were 56% and 26%. It was shown by receiver operating characteristic curves that the combined sensitivity and specificity of the screening questionnaire was superior to that of the physician ratings.(ABSTRACT TRUNCATED AT 250 WORDS)
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We examined several aspects of cell division regulation in Escherichia coli which have been thought to be controlled by cyclic AMP (cAMP) and its receptor protein (CAP). Mutants lacking adenyl cyclase (cya) or CAP (crp) were rod shaped, not spherical, during exponential growth in LB broth or glucose-Casamino Acids medium, and lateral wall elongation was normal; in broth, stationary-phase cells became ovoid. Cell mass was smaller for the mutants than for the wild type, but it remained appropriate for their slower growth rate and thus probably does not reflect early (uncontrolled) septation. The slow growth did not seem to reflect a gross metabolic disorder, since the mutants gave a normal yield on limiting glucose; surprisingly, however, the cya mutant (unlike crp) was unable to grow anaerobically on glucose, suggesting a role for cAMP (but not for CAP) in the expression of some fermentation enzyme. Both cya and crp mutants are known to be resistant to mecillinam, an antibiotic which inhibits penicillin-binding protein 2 (involved in lateral wall elongation) and also affects septation. This resistance does not reflect a lack of PBP2. Furthermore, it was not simply the result of slow growth and small cell mass, since small wild-type cells growing in acetate remained sensitive. The cAMP-CAP complex may regulate the synthesis of some link between PBP2 and the septation apparatus. The ftsZ gene, coding for a cell division protein, was expressed at a higher level in the absence of cAMP, as measured with an ftsZ::lacZ fusion, but the amount of protein per cell, shown by others to be invariable over a 10-fold range of cell mass, was independent of cAMP, suggesting that ftsZ expression is not regulated by the cAMP-CAP complex.
Three groups of male transsexuals at different stages of the treatment process were examined and shown to match retrospectively in actuarial and psychiatric data. Transsexuals who were on a waiting list for surgery showed lower neurotic scores on the Crown-Crisp Experiential Index than those at the assessment stage of clinic attendance, while post-operative transsexuals obtained scores lower than either of the other groups. Transsexuals during the assessment stage of treatment obtained the lowest scores on items in the Bem Sex Role Inventory that define stereotypical masculine characteristics and the highest scores on items that define stereotypical feminine characteristics, in relation to the other two groups.
Escherichia coli like most gram-negative bacteria with walls maintains a cytoplasmic osmolarity exceeding that of the medium; the resulting hydrostatic pressure (turgor pressure) pushes the cytoplasmic membrane against the peptidoglycan and creates a tension in the two envelopes. Potassium is the only cation which takes part in the regulation of cellular osmolarity. The adaptation of intracellular K+ concentration to external osmolarity involves K+ turgor-controlled fluxes. When the medium osmolarity is raised an osmodependent influx of K+ can be observed; this is carried out by the K+ transport system TrkA which can also taken up rubidium. A specific and unidirectional pathway allows K+ ions to flow out of the cell when the medium osmolarity is decreased; this pathway reveals two characteristics: it has no affinity for rubidium and it can be blocked by the blockers of eukaryotic K+ channels. Osmodependent fluxes are turned on immediately after the medium osmolarity is disturbed; in contrast, they are turned off gradually as the rate of K+ fluxes approach zero. The rate of K+ influx seems to depend on the level of internal osmolarity and not on the extent of the increase in medium osmolarity. The rate of the efflux is directly proportional to the decrease in medium osmolarity and is independent on the level of internal osmolarity.
Glutathione-deficient mutants of Escherichia coli, unlike the wild type, exhibit a fast leak and a fast turnover of K+ at steady state. In a medium with low K+ the growth rate is very slow when unsupplemented with glutathione; when supplemented with glutathione at a concentration as low as 0.1 microM the growth rate is similar to that of the wild type. The ability of glutathione to restore a wild-type growth rate can be accounted for by an immediate reduction of the K+ leak. Two analogs of glutathione also reduce the K+ leak: gamma-glutamylaminobutyrylglycine (ophthalmic acid) and alpha gamma-glutamylcystinylbisglycine. Glutathione binds with high affinity (Kd 50 nM) to a cytoplasmic protein; ophthalmic acid and alpha gamma-glutamylcystinylbisglycine compete with glutathione for the binding site (Ki 0.1 microM and 1 microM), thereby ruling out the possibility that the thiol is involved both in reducing the K+ leak and in binding to the high affinity binding site. For each of the three peptides the Kd for binding is similar to the minimal concentration that achieves the maximal reduction of the K+ leak. The results suggest that the binding of glutathione should play a role in the retention of K+ in E. coli.
Patients were treated with three different types of electroconvulsive therapy in random order in the first three sessions of their courses. Anaesthetic and muscle relaxants were administered in standard doses, and treatment applied a set time after bolus injection. Electroencephalographic recordings were undertaken before, during, and after treatment, and hormonal measures before and after. The responses to treatment differed between the three types of current in both EEG and prolactin measures. It is suggested that the quality of the convulsive response varies with different currents.
Consistent with the model of an H+ cotransport, amino acid uptake can be driven by a proton gradient generated by an efflux of sugar when the normal energy sources are suppressed. Heterologous countertransport is completely inhibited by uncouplers unlike homologous countertransport. Positive coupling was obtained with methyl thiogalactoside/proline, methyl thiogalactoside/phenylalanine, gluconate/proline; however, the poor coupling efficiency suggests a more complex sequence of reactions.
Laser scotometry is an accurate means of detecting dense blind spots. A small low-energy spot is guided across the fundus from nonseeing to seeing areas. Patient responses are recorded on fundus photographys, allowing direct correlation with fundus pathology. Accuracy to less than 1 degree is feasible. All typical optic nerve drusen tested with this technique had field defects. In cases of optic nerve pits, dense scotomas correlated with the shape of visible nerve fiber defects rather than with the shape of serous retinal detachments.
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Explore the source record for details and available documents.