Biomedical subjects
S Johnson
Publications and source records attributed to S Johnson.
Systemic mastocytosis and mastocytosis-like syndrome: radiologic features of gastrointestinal manifestations.
Mastocytosis is a disorder of unknown etiology characterized by an abnormal proliferation of tissue mast cells, and/or by degranulation of abnormally behaving mast cells that show no proliferation, but release myriad active metabolites. This results in a wide spectrum of signs and symptoms that fluctuate considerably. The presently available diagnostic tests vary in their specificity and sensitivity. We have evaluated the role of radiologic studies in 78 confirmed cases of systemic mastocytosis and/or mastocytosis-like syndrome, including barium meal and small bowel follow-through (UGI-SBFT).
Pathogenesis of postoperative hyponatraemia following correction of scoliosis in children.
Eight paediatric patients undergoing major surgery for correction of scoliosis who were treated postoperatively with hypotonic saline and 5% dextrose have been studied. Plasma sodium, renin and aldosterone, and urine volume, sodium and osmolality were measured. These patients had an impaired ability to excrete a sodium-free water load. In the first 60 h urine volume remained reduced, while in the first 36 h urine sodium remained concurrently high. If the first 36 h postoperation are considered, the sodium-free water given was quantitatively retained and the serum sodium at 36 h was significantly correlated with the amount of free water given (P less than 0.01). To minimize postoperative hyponatraemia and the associated shift of water into the brain causing cerebral oedema, it is recommended that no more than 50 ml/kg sodium-free water be given until urine sodium falls and volume increases.
Rebreathing method for the simultaneous measurement of oxygen consumption and effective pulmonary blood flow during exercise.
This paper describes a rebreathing method for the simultaneous measurement of oxygen consumption (VO2) and effective pulmonary blood flow (QP. eff) at rest and during exercise. Subjects rebreathed a test gas consisting of 35% oxygen, 3.5% chlorodifluoromethane (freon-22), and 10% argon in nitrogen for 30 seconds or until the respired oxygen tension fell to below 13.3 kPa. Sixty normal subjects were studied on a motorized treadmill, the Bruce protocol being used. The rebreathing manoeuvre was performed at three minute intervals, and was initially practised sitting down. Measurements were then made with the subjects standing at rest, and subsequently during the last minute of each stage of the Bruce exercise protocol until the subjects were exhausted. Heart rate was recorded from the electrocardiogram. Oxygen uptake plotted against calculated power (watts) showed a discontinuity between resting and exercise values, probably because power output during treadmill exercise is underestimated. The arbitrary addition of 30 watts to the exercise power output abolished this discontinuity. There was good agreement between rebreathing estimates of oxygen consumption and values measured during a second exercise test by the conventional open circuit argon dilution method. Coefficients of variation of oxygen consumption and effective pulmonary blood flow measured by rebreathing were usually less than 10% even during maximal exertion. At rest mean (SD) effective pulmonary blood flow corrected for body surface area was 2.2 (0.46) l/min/m2. Effective pulmonary blood flow rose linearly with oxygen consumption. At rest the arteriovenous oxygen content difference for pulmonary blood (VO2/QP eff) was 9.1 (1.6) ml/dl, rising to a maximum of 16.4 (1.8) ml/dl. The stroke volume index was 27.5 (6.8) ml/m2, rising to a maximum of 46.5 (7.1) ml/m2 during exertion.
Dental caries continues downward trend in children.
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Heterosexual and perinatal transmission of human immunodeficiency virus in a low prevalence community.
Six previously unidentified cases of human immunodeficiency virus (HIV) infection were found during an investigation and follow-up of three clusters of heterosexually and perinatally transmitted HIV infections. The investigations were to identify those infected, to interrupt the transmission of HIV, to attempt to reduce the likelihood of the development of the acquired immunodeficiency syndrome among those found to be seropositive, and to show the usefulness of traditional disease control strategies during this epidemic. Our findings indicate the value of contact tracing for HIV infections and the need to provide and evaluate educational activities regarding the transmission of HIV in low prevalence populations.
Enteritis necroticans among Khmer children at an evacuation site in Thailand.
A severe illness characterised by bloody diarrhoea and intestinal dysfunction was recognised at an evacuation site on the Thai-Kampuchean border. From June, 1985, to July, 1986, the illness occurred in 62 Khmer children aged 10 months to 10 years (mean 4 years); it was characterised by bloody diarrhoea (94%), fever (90%), and abdominal pain (78%). The overall mortality rate was 58%. Among 16 children who died and underwent necropsy, small-intestinal necrosis of varying severity was found; in 5 of these children small-intestinal lesions with areas of full-thickness necrosis were seen that histologically resembled those in cases of enteritis necroticans (pigbel) in Papua New Guinea. Beta-toxin-producing Clostridium perfringens type C was isolated from 2 of 23 children from whom specimens for anaerobic cultures were collected, and antibodies to beta toxin were detected in 5 of 9 survivors but not in 10 healthy, age-matched control children. These cases show that enteritis necroticans can cause substantial morbidity and mortality outside Papua New Guinea.
Absence of HIV infection in prostitutes and women attending sexually-transmitted disease clinics in South Africa.
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An 8;14 translocation in a case of plasma cell leukemia.
We report a patient with plasma cell leukemia. Chromosomal analysis of bone marrow showed hypodiploidy with a modal number of 32, and a t(8;14). This is only the second reported case of t(8;14) in plasma cell leukemia.
Chromosome abnormalities involving band 13q14 in hematologic malignancies.
Fifteen patients with hematologic disorders showed abnormalities involving chromosome band 13q14. Nine patients had an interstitial deletion of this band, similar to that reported in some retinoblastoma tumors and as a constitutional abnormality in a small proportion of cases of familial retinoblastoma. In five patients, band 13q14 was involved in translocations and in one case there was a deletion of one chromosome #13 and a translocation involving the homologous #13. The diagnosis in the majority of our patients (11 of 15) was chronic lymphocytic leukemia. In these patients the abnormalities were detected in cultures stimulated with 4-phorbol 12-myristate 13-acetate (PMA). It is possible that the utilization of this agent is a fundamental requirement for the reliable demonstration of abnormalities involving 13q14 in patients with B-cell malignancies. The incidence of abnormalities involving 13q14 and their significance in the development of neoplasias, other than retino-blastoma, is discussed.
Infant hearing screening: program implementation and validation.
Congenital and early-onset hearing losses were discovered in 6.1% of 975 Intensive Care Nursery (ICN) graduates. The methods used were neonatal screening by Crib-O-Gram (COG) and high risk register, in combination with repeated behavioral hearing tests at 1 to 3 years. This 7-year longitudinal study had follow-up hearing evaluations for a remarkably high 84% of all subjects. Significant losses that interfered with speech and language development (1000 to 8000 Hz average loss greater than 45 dB HL bilaterally) were found in 4.3% of infants. COG in combination with subsequent behavioral hearing screening was a sensitive strategy for detecting significant hearing loss: only one child was missed with this combination. Alone, COG sensitivity to significant hearing losses was 79.3%, but would have been higher had a stricter passing criterion been adopted. Behavioral hearing screenings detected bilateral hearing losses of even mild (greater than 20 dB HL) degree. Sensitivity to significant hearing losses was 82.6% and would have been improved if test frequencies greater than 3000 Hz were included in the screen. Even if screening failure occurred at 1 year of age, the age of actual confirmation of hearing loss depended on severity of the loss and ear involvement. Significant hearing losses were confirmed earlier than less severe or unilateral losses. Although behavioral screenings could be done during the first year of life, continued follow-up was required to detect progressive hearing losses.
Tear and serum antibody response to Chlamydia trachomatis antigens during acute chlamydial conjunctivitis in monkeys as determined by immunoblotting.
In this study, we examined the temporal antibody response by immunoblotting analysis in tears and sera of three cynomolgus monkeys (Macaca fasicularis) with primary acute Chlamydia trachomatis serovar B conjunctivitis. The objective was to identify chlamydial antigens stimulating antibody during the host responses in the course of this self-limiting infection with the rationale that they may be protective antigens. The major outer membrane protein (MOMP), lipopolysaccharide (LPS), and polypeptides of 60 and 68 kilodaltons (kDa) were the predominant antigens recognized by immunoglobulin A (IgA) in monkey tears. Tear IgA antibody specific for the MOMP was first detected 14 days postinfection, whereas tear IgA reactive with LPS or the 68- and 60-kDa polypeptides was first detectable on day 21. Tear IgA antibodies specific for each of these antigens persisted in tears through day 56, 4 weeks after both peak clinical disease and recovery of the organism from the conjunctivae. In contrast, tear IgG antibodies peaked at approximately 28 days postinfection, the time of maximal inflammatory response. The IgG response in monkey sera was similar to that observed for tear antibodies, in that the MOMP, 60-, and 68-kDa polypeptides were the primary immunogens. The exception was that IgG antibody against these antigens was detected 1 week later than that observed for tear IgA antibodies. Of three monkeys that responded with tear IgA antibody against LPS, one did not have detectable serum IgG LPS antibody. The specificity of the tear IgA antibody response of monkeys was determined by immunoblotting nine other C. trachomatis serovars in addition to the homologous B serovar. The tear IgA response to the MOMP was predominantly B complex subspecies-specific (serovars B, Ba, D, and E), whereas the response to chlamydial LPS was found to be species-specific. The significance of these observations in relation to previous vaccine studies in nonhuman primates is discussed.
Survey of adult dental health.
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Urethroplasty with balloon catheter in prostatic hypertrophy.
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Pharmacological management of manic psychosis in an unlocked setting.
There has been a resurgence in the past few years of exploring alternative pharmacological agents in the management of manic psychosis. An open clinical trial was conducted on an unlocked ward investigating the use of benzodiazepines as adjunctive therapy with lithium or carbamazepine, with some of the patients also receiving neuroleptics. Twelve patients meeting DSM-III criteria for bipolar affective disorder, manic type, were treated. Patient response was monitored with use of the Brief Psychiatric Rating Scale and the Biegel Mania Rating Scale. The patients all had moderately severe illness upon initiation of the trial. Results indicate that those patients who received benzodiazepines alone were among the better responders, and that when used in combination with neuroleptics, the dose of each drug was quite small. Minimal side effects were noted with this regimen. Our preliminary results suggest that benzodiazepines may be useful as adjunctive treatment in the management of patients with bipolar affective disorder, manic type.
Media for the isolation of Shigella.
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Differences in antimicrobial susceptibilities of clinical isolates in Saudi Arabia and the United States.
In vitro antimicrobial susceptibilities of 3,530 clinical isolates at King Faisal Specialist Hospital and Research Center (KFSH), in Riyadh, Saudi Arabia, were compared with those of 11,041 bacterial isolates at two hospitals of comparable size in the United States. The gram-negative bacteria, especially Escherichia coli, Proteus-Morganella group, Enterobacter sp, Serratia marcescens, and Pseudomonas aeruginosa were generally more resistant to ampicillin, carbenicillin, cephalosporin, gentamicin, piperacillin, and trimethoprim-sulfamethoxazole at KFSH than in the United States. A larger number of isolates of Klebsiella pneumoniae were more resistant to cephalosporin, chloramphenical, gentamicin, piperacillin, and trimethoprim-sulfamethoxazole at one of the tertiary care hospitals in the United States. Hemophilus influenzae and gram-positive cocci exhibited similar susceptibilities toward commonly used antibiotics at all three institutions.
Laboratory studies of the 1984 influenza epidemic on the Witwatersrand.
A particularly severe outbreak of influenza occurred on the Witwatersrand from May to August 1984, caused sequentially by influenza A (H3N2), B/influenza and influenza A (H1N1) viruses. Although the precise extent of the infection was impossible to determine, valuable anecdotal information was provided by a network of sentinel sampling stations in private practices, clinics and hospitals, representing a cross-section of population groups on the Witwatersrand. This active surveillance programme was invaluable in providing some 85% of all the specimens, the remainder being routine clinical specimens; in addition, isolation was approximately twice as efficient for the actively acquired specimens than for the routine ones. The epidemic affected all individuals approximately equally, regardless of age, race or socio-economic status. Infection with H1N1 virus tended to predominate in the younger age group, 78% of isolates being from subjects under 30 years of age, whereas 71% of H3N2 isolates came from subjects over 30 years of age. The B/influenza isolates tended to be more evenly dispersed. Novel strains of B/influenza and H1N1 viruses were introduced into the country and possibly contributed to the greater than usual severity of the epidemic. An active surveillance programme is essential to monitor the extent of influenza virus activity and to alert virologists to the introduction of new strains, although at present forecasting of future influenza epidemics is not possible with any significant degree of reliability.