Hepatitis B in Johannesburg schoolchildren--no need to panic.
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Child↗
Biomedical subjects
D J Martin
Publications and source records attributed to D J Martin.
Nonspecificity of serological tests for cytomegalovirus.
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Antibodies, Viral↗
Xyloglucan endotransglycosylase, a new wall-loosening enzyme activity from plants.
1. Cell-free extracts of all plants tested contained a novel enzyme activity (xyloglucan endotransglycosylase, XET) able to transfer a high-Mr portion from a donor xyloglucan to a suitable acceptor such as a xyloglucan-derived nonasaccharide (Glc4Xyl3GalFuc; XG9). 2. A simple assay for the enzyme, using [3H]XG9 and based on the ability of the [3H]polysaccharide product to bind to filter paper, is described. 3. The enzyme was highly specific for xyloglucan as the glycosyl donor, and showed negligible transglycosylation of other polysaccharides, including CM-cellulose. 4. The Km for XG9 was 50 microM; certain other 3H-labelled xyloglucan oligosaccharides also acted as acceptors, and certain non-radioactive xyloglucan oligosaccharides competed with [3H]XG9 as acceptor; the minimum acceptor structure was deduced to be: [formula: see text] 5. The pH optimum was approx. 5.5 and the enzyme was less than half as active at pH 7.0. The enzyme was slightly activated by Ca2+, Mg2+, Mn2+, spermidine, ascorbate and 2-mercaptoethanol, and inhibited by Ag+, Hg2+, Zn2+ and La3+. 6. XET activity was essentially completely extracted by aqueous solutions of low ionic strength; Triton X-100, Ca2+, La3+, and Li+ did not enhance extraction. Negligible activity was left in the unextractable (cell-wall-rich) residue. 7. The enzyme differed from the major cellulases (EC 3.2.1.4) of pea in: (a) susceptibility to inhibition by cello-oligosaccharides, (b) polysaccharide substrate specificity, (c) inducibility by auxin, (d) requirement for salt in the extraction buffer and (e) activation by 2-mercaptoethanol. XET is therefore concluded to be a new enzyme activity (xyloglucan: xyloglucan xyloglucanotransferase; EC 2.4.1.-). 8. XET was detected in extracts of the growing portions of dicotyledons, monocotyledons (graminaceous and liliaceous) and bryophytes. 9. The activity was positively correlated with growth rate in different zones of the pea stem. 10. We propose that XET is responsible for cutting and rejoining intermicrofibrillar xyloglucan chains and that it thus causes the wall-loosening required for plant cell expansion.
Carbohydrate Sequence↗
Prenatal demonstration of a cervical myelocystocele.
Myelocystocele is a rare spinal cord disorder and has not been described prenatally. We report a case in which prenatal ultrasound and magnetic resonance imaging (MRI) demonstrated a posterior cervical mass which was initially thought to be a meningocele or an atypical cystic hygroma. Surgery performed at 1 day of age showed this to be a myelocystocele. Therefore, the differential diagnosis of an extracranial cystic mass in the posterior cervical region should be expanded to include myelocystoceles.
Adult↗
Plain film and CT observations in prostaglandin-induced bone changes.
Prostaglandin E1 intravenous infusion is used in infants with ductal-dependent congenital heart disease to maintain ductal patency and prolong life until palliative or corrective surgery is feasible. Complications of prostaglandin administration include fever, diarrhoea, hypotension, apnoea, bradycardia, pseudowidening of the cranial sutures, underossification of the calvarial bones, periostitis, and skin edema [1-3]. This paper presents dramatic plain radiographic features of prostaglandin-induced bone disease, including periosteal proliferation and the unusual bone-within-bone appearance, and provides the previously unpublished CT correlation.
Alprostadil↗
Evaluation of renal scars by technetium-labeled dimercaptosuccinic acid scan, intravenous urography, and ultrasonography: a comparative study.
The objective of our prospective study was to compare the sensitivity and specificity of ultrasonography, intravenous pyelography, and dimercaptosuccinic acid scan in detecting scarred kidneys. Twenty-seven consecutive subjects with recurrent urinary tract infections, vesicoureteral reflux, scarred kidneys, or a combination of these problems had all three imaging procedures performed. With the total number of scars serving as the gold standard, the sensitivity (94%) and specificity (100%) in identifying renal scars in children were highest for the DMSA scan. Intraobserver (95%) and interobserver (90%) reliability were also high for the DMSA scan. However, the clinical interpretation of the increased sensitivity of the DMSA scan is unknown. Changes on the scan not identified by intravenous urography may not represent true scars. Research into the long-term significance of these scars is indicated.
Adolescent↗
Differential effects of endothelin-1 on the vasorelaxant properties of benzopyran and non-benzopyran potassium channel openers.
1. The effects of endothelin-1 (ET-1) on the vasorelaxant properties of structurally different potassium channel openers (PCOs), BRL-38227, Ro 31-6930, SDZ PCO 400, EMD-52692, RP-49356 and pinacidil, were studied. 2. All PCOs evoked concentration-related relaxations of ET-1 (10 nM) or KCl (20 mM) contracted rat isolated aortic rings denuded of endothelium. BRL-38227, EMD 52692, SDZ PCO 400 and Ro 31-6930 were 11-42 times less potent in relaxing contractions to ET-1 than KCl. In contrast, this differential potency was not observed with RP-49356 or pinacidil. 3. BRL-38227 (0.06-3.0 microM), RP-49356 (0.3-3.0 microM) and pinacidil (0.3-3.0 microM) displaced KCl concentration-response curves to the right of controls, without modifying the maximum response. A subcontractile concentration of ET-1 (0.1 nM) prevented the inhibitory effects of low concentrations of BRL-38227 (0.06-0.1 microM) on KCl responses, but failed to modify those to RP-49356, pinacidil or high concentrations of BRL-38227 (0.3-3.0 microM). The inhibitory effects of BRL-38227 (0.1 microM) were also not changed by ET-3 (1.0 nM) or angiotensin II (0.1 nM). 4. In anaesthetized spontaneously hypertensive rats (SHR), cumulative bolus intravenous administrations of BRL-38227 (1-1000 micrograms kg-1, i.v.), Ro 31-6930 (1-1000 micrograms kg-1, i.v.), RP-49356 (10-1000 micrograms kg-1, i.v.) or nitrendipine (0.1-30 micrograms kg-1, i.v.) produced dose-dependent falls in diastolic blood pressure (DBP).ET-1 (i.v.) evoked a transient fall in DBP (1 pg kg- = 58 + 1 mmHg) which returnedto pre-administration levels within 4 min.5. Pretreatment of anaesthetized SHR with ET-l (1 pg kg-', i.v.) significantly increased the ED,5 (dose to evoke a 15% fall in DBP) values for BRL-38227 and Ro 31-6930. However, ET-l failed to modify the ED,5 values for RP-49356 or nitrendipine. The ED50 values for all of the vasodilators studied were not modified by ET-1.6. Infusion of BRL-38227 (2 pgkg-'min-', i.v.) or RP-49356 (4 pgkg-'min', i.v.) to anaesthetized SHR evoked dose-related falls in DBP, with a corresponding increase in descending aortic blood flow (DABF) and a decrease in total lower body vascular resistance (TLBVR). Pretreatment with ET-1 (1 ptg kg-', i.v.) significantly attenuated the decreases in DBP and TLBVR observed with low doses of BRL-38227, but not RP-49356 or high doses of BRL-38227. In contrast, ET-3 (3 pig kg-, i.v.) failed to modify the effects of BRL-38227 on DBP or TLBVR.7. In conscious SHR, the fall in DBP to BRL-38227 (30 pgkg-', p.o.) was significantly reduced following ET-1 (1 pig kg-', i.a.) treatment. ET-1 (1 pg kg-', i.a.) pretreatment, however, failed to modify the decrease in DBP induced by an equieffective oral dose of RP-49356 (1001pgkg-1).8. In conclusion, ET-1 selectively attenuated the vasorelaxant effects of the potassium channel opener,BRL-38227 and other substituted benzopyrans. The results are compatible with the hypothesis that benzopyran PCOs and ET-1 have affinity for a site that does not recognise RP-49356 or pinacidil. Thus,ET-l can differentiate between structurally unrelated potassium channel openers. The cardiovascular effects of some, but not all, PCOs might be radically modified in the clinical setting by elevated endogenous levels of ET-1 associated with certain diseased states.
Animals↗
Hepatitis A vaccination--an option for South Africa?
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Hepatitis A↗
Recurrent hemarthrosis associated with gout.
Gout commonly occurs as an acute arthritis. In a 64-year-old man, gout was associated with a proliferative hemosiderin-laden synovitis. The association of recurrent atraumatic hemarthrosis seems not to have been reported in the literature on gout.
Gout↗
Katayama fever in scuba divers. A report of 3 cases.
Katayama fever or acute schistosomiasis probably occurs more commonly than is recorded. Interviews with a 3-man scuba diving team who had had contact with a large dam in an endemic area of the eastern Transvaal Lowveld at the same time and contact area on the same day during late summer of 1986 are discussed. Two, who had not previously been exposed to infected water, presented with Katayama fever, due to Schistosoma mansoni infection, 21 days after contact and it took 30-36 months for them to recover fully after several treatments. The third patient, a keen water-sportsman and resident in the endemic area for a period of 10 years, presented with a mild infection, probably due to acquired immunity initiated during previous contacts with infected water; he took about a year to recover. The pathogenesis, clinical features, diagnosis and treatment of the 3 cases are described in the light of recent observations made elsewhere on Katayama fever cases and the effects of chemotherapy on the course of illness. The necessity of obtaining basic information on the travel and water-contact activities of patients in order to make a diagnosis is emphasised.
Acute Disease↗
Major depressives' and dysthmics' performance on the Wisconsin Card Sorting Test.
Despite awareness that depression may affect performance on commonly used neuropsychological tests, little research has been conducted on the relative impact of severity and type of depression on higher problem-solving ability. Major depressives (n = 13), dysthymics (n = 17), and non-psychiatric comparison subjects (n = 18) were administered the Wisconsin Card Sorting Test (WCST). Although diagnostic category was related only marginally to some WCST measures after controlling for intellectual function, depressive symptom severity emerged as an independent predictor of Total Errors, Perseverative Responses, and Failure to Maintain Set. These findings lend support to the suggestion that neuropsychological test batteries should include assessment for depression and suggest that even relatively mild depression may affect WCST scores.
Attention↗
Intraabdominal pulmonary sequestration.
A left upper quadrant fetal abdominal mass was detected at 24 weeks gestation. The mass was again confirmed in a postnatal ultrasound. Pathological analysis of the excised mass demonstrated an intraabdominal lung sequestration with Stocker type II congenital cystic adenomatoid malformation (CCAM). The sonographic characteristic of these lesions are those of a homogeneous echogenic mass with variable shape passing through or arising from the diaphragm. Surgical excision is recommended because of the uncertainty of the preoperative diagnosis and the possibility of malignant changes in CCAM.
Abdomen↗
Prenatal ultrasonographic diagnosis of dicephalus conjoined twins.
The authors report the prenatal diagnosis by ultrasonography of dicephalus dipus dibrachius conjoined twins (with two heads, one body, two legs and two arms) at 31 weeks' gestation. They discuss the types of conjoined twinning and their frequency of occurrence and the criteria for prenatal diagnosis, and they offer recommendations for management.
Adult↗
AIDS and tuberculosis.
The diagnostic and therapeutic implications of human immunodeficiency virus (HIV) infection and tuberculosis in South Africa, where tuberculosis remains a major health problem, are reviewed. Mycobacterium tuberculosis is a high-grade pathogen and is able to establish infection early in immunodeficiency. With HIV infection showing significant entry into the heterosexual population in the RSA, an increasing number of cases with both infections can be expected to occur. The radiological appearance in combined infection is variable, ranging from a formal cavitatory picture to the more common finding of diffuse pulmonary infiltration. Intrathoracic adenopathy is a more specific sign of tuberculosis in HIV infection, since it is not associated with persistent generalised lymphadenopathy and pulmonary opportunistic infections, such as Pneumocystis carinii pneumonia. Intercurrent pneumonic infections and other pulmonary manifestations of HIV disease render the interpretation of new infiltrates on chest radiography problematical. Tuberculin skin testing remains useful in HIV infection and should be performed in all HIV-infected patients. The value of tuberculosis serology still remains questionable. Standard antituberculosis drug regimens are effective, but maintenance treatment must be continued for life and should include isoniazid and rifampicin. BCG vaccination is recommended routinely at birth in infants with HIV infection and for asymptomatic HIV-infected individuals who have not previously been immunised.
Acquired Immunodeficiency Syndrome↗
Novel recombinations of the IG kappa-locus that result in allelic exclusion.
Allelic exclusion of Ig H and L chain gene loci serves to ensure that a B cell expresses a single specificity antibody. The analysis of Abelson murine leukemia virus transformed cells that rearrange the kappa-locus during growth in cell culture has provided the opportunity to characterize intermediate steps in Ig gene rearrangement. By sequential cloning of an Abelson murine leukemia virus transformed cell line we have observed a novel two-step pathway that results in a rearrangement of a V kappa gene segment into the J-C kappa intron. This type of rearrangement effectively excludes functional kappa expression from that allele. A truncated mRNA product resulting from the V kappa signal exon splicing to the C kappa exon is diagnostic of these unique rearrangements. In addition to demonstrating a novel mechanism for allelic exclusion, the two-step pathway described serves to explain how V-intron recombination products were generated in previously described cell lines.
Alleles↗
Considerations on the further expansion of the AIDS epidemic in South Africa--1990.
An epidemiological composite of the human immunodeficiency virus (HIV) epidemic in South Africa was constructed from reported acquired immunodeficiency syndrome (AIDS) figures, blood donor seroprevalence data and a family of active surveillance studies in the Johannesburg area. Of great concern is the extensive and continuing silent spread of HIV in the urban black population, manifested by doubling times in male and female sexually transmitted disease (STD) clinic attenders of 10.67 and 9.78 months respectively, a doubling time in female family planning (FP) attenders of 6.55 months, and HIV infection rates of 1:56, 1:37 and 1:91, respectively. These data suggest a spread of infection far more extensive than the relatively lower AIDS figures. However, seroprevalence figures in municipal employees of mainly rural origin were considerably lower, only 1:1,250 in black men and none in women, but regular movements between urban and rural areas could well introduce and amplify infection in rural areas. A complete epidemiological picture of HIV can only be attained by employing both the above approach of the family of surveys complemented by a nationwide seroprevalence study to assess HIV penetration into the general 'background' population. Educational interventions should now be particularly targeted to the major risk groups in the urban black heterosexual community.
Acquired Immunodeficiency Syndrome↗
The frequency of multiple recombination events occurring at the human Ig kappa L chain locus.
Products of Ig kappa L chain gene rearrangement in a variety of human B cell samples were investigated by sequential Southern blot hybridization analysis. By application of four region-specific probes (C kappa, J kappa, U' kappa and kappa de) a complete spectrum of kappa rearrangements, including both predicted and novel products, were detected. Nearly 30% of the products detected reflect multiple recombination of the kappa locus. The kappa-deleting element was responsible for 70% of the multiple rearrangements that were detected. Interestingly, eight kappa-expressing samples exhibited rearrangement of the kappa-deleting element. The remaining multiple recombination products were characteristic of double V kappa-J kappa rearrangement. This frequency reveals that secondary V-J rearrangement may significantly contribute to the expression of kappa L chains in humans.
Alleles↗
Ultrasonography in the management of possible appendicitis in childhood.
One hundred thirty-four children referred to the pediatric surgical service with the diagnosis of possible acute appendicitis underwent abdominal ultrasonography within 24 hours of admission. A final diagnosis of appendicitis was made in 45, and of gynecological disease in 11 children. One child had pancreatitis, another jejunal perforation, and a third gross mesenteric lymphadenopathy. In 75 children the clinical picture completely resolved without a definitive diagnosis being made. Clinical diagnosis of gynecological disease showed two false-negatives, and three false-positives, whereas the ultrasonographic diagnosis was accurate in all patients. The sensitivity of the pediatric surgical diagnosis at the time of admission for acute appendicitis was 49% (23 false-negatives) and the specificity was 95% (three false-positives). Ultrasonographic diagnosis of appendicitis had a sensitivity of 89% (five false-negatives) and a specificity of 92% (five false-positives). There was a negative laparotomy rate of 0.7% (one patient) using both clinical evaluation and ultrasonography. These data suggest that abdominal ultrasonography in the child with possible appendicitis is an important diagnostic adjunct.
Abdominal Pain↗