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Biomedical subjects

S Brink

Publications and source records attributed to S Brink.

At least 73 records · Page 4Linked to original sources
PubMed1994

The 24 kDa outer envelope membrane protein from spinach chloroplasts: molecular cloning, in vivo expression and import pathway of a protein with unusual properties.

The 24 kDa outer envelope membrane protein of spinach chloroplasts (omp24) represents a major constituent of this membrane. Sequences of tryptic and endoprotease Glu-C peptides derived from omp24 allowed the design of oligonucleotides which were used to generate a DNA fragment by polymerase chain reaction using spinach cDNA as template. This fragment served as a probe to screen a cDNA library for a full-length clone of the omp24 coding sequence. The protein predicted from the complete sequence only has 148 amino acids and a molecular mass of 16294 Da. It is an acidic protein (calculated isoelectric point 4.8) with a high content of proline residues. Expression of the coding sequence in Escherichia coli and characterization of the purified recombinant protein produced revealed that the overestimation of its molecular mass by SDS-PAGE (ca. 25 kDa) is due to its abnormal amino acid composition. Despite its rather low hydrophobicity (polarity index 49%), omp24 appears to be deeply embedded in the outer membrane. Insertion of omp24 into the membrane proceeds almost independently of surface receptors or targeting sequence but, in contrast to other known outer envelope membrane proteins, is stimulated by ATP.

Amino Acid Sequence↗
PubMed1994

Cloning and in vivo expression of functional triose phosphate/phosphate translocators from C3- and C4-plants: evidence for the putative participation of specific amino acid residues in the recognition of phosphoenolpyruvate.

The primary sequences of the chloroplast triose phosphate/phosphate translocator precursor proteins from C4-plants (maize mesophyll cells and Flaveria trinervia) and from the C3-type Flaveria pringlei were determined. The mature parts of these translocators possess 83-94% identical amino acid residues. The C4-translocator protein can be correctly targeted to C3-type chloroplasts and inserted into the envelope membrane. Expression of the mature parts of these chloroplast translocators (cTPT) in transformed yeast cells and subsequent reconstitution of the functional proteins reveals the difference between the recombinant translocator proteins from the two cell types with respect to the transport of phosphoenolpyruvate. Comparison of the cTPT sequences from F. pringlei and F. trinervia in combination with computer-aided molecular modelling of the substrate translocation pore leads to the suggestion, that only minor exchanges of amino acid residues between the C3- and C4-translocator proteins are sufficient to extend their substrate specificities to recognize also phosphoenolpyruvate.

Amino Acid Sequence↗
PubMed1989

The relationship of anticardiolipin antibodies to disease activity in systemic lupus erythematosus.

Sera from 124 blood donors, 60 rheumatoid arthritis (RA) and 57 SLE patients were measured for anticardiolipin antibodies by ELISA. Significantly raised IgG (aCLG) and IgM (aCLM) anticardiolipin antibody levels were found in RA and SLE (p less than 0.0005). However, in SLE both aCLG and aCLM levels were significantly higher than in RA (p less than 0.0025). We then conducted a transectional study to evaluate aCL levels and disease activity in SLE. There was a good positive predictive value (70%) between aCL and overall disease activity, but not for individual systems. A strong association between aCL and renal involvement irrespective of activity was also found (80%). Nine SLE patients fulfilled both the clinical and serological criteria for the antiphospholipid syndrome (APS) and a further 18 patients fulfilled the serological criteria for APS. Results indicate that aCL levels are of value in predicting overall disease activity in SLE and in monitoring those patients who fulfil or partially fulfil the criteria for APS.

Adolescent↗
PubMed1988

Allergic asthma in different population groups in the western Cape. Causative and complicating factors.

Allergic asthma is a disease with a well-defined aetiology, the recognition and elimination of which could be achieved with relatively simple and inexpensive prophylactic treatment. Some of the well-known factors--respiratory tract infections, exposure to cigarette smoke, specific antigens and regular application of prophylactic treatment--which could cause or complicate asthma were studied in groups of white and coloured patients. More respiratory tract infections occurred in coloured patients and they were more exposed to their own and secondary cigarette smoke. Pets and grass pollen allergenicity was more common among whites while allergy to Aspergillus fumigatus and Ascaris lumbricoides was found more frequently among coloured patients. Both white and coloured patients had problems with regular prophylactic control of their symptoms with inhaled beta-stimulants, even after an average of two education sessions per patient, but this was of greater dimension for the coloured (60%) than the white group (27%) (P less than 0.001). It is not possible to separate causative from genetic factors when studying asthma in different population groups, but recognition of prevailing causative factors for each group could stimulate an educational approach aimed at control by prevention rather than treatment of acute attacks.

Adolescent↗
PubMed1987

Effectiveness and cost effectiveness of persuasive communications and incentives in increasing safety belt use.

The Safety Belt Connection Project was a worksite health promotion project conducted at a medical school and hospital complex to test the effectiveness and cost effectiveness of four treatment conditions (TCs): TC1, Persuasive Communications (PCs) alone; TC2, PCs plus overt monitoring; TC3, PCs plus incentives; and TC4, PCs plus incentives and prompts. Parking lots were randomized to treatment condition. A community traffic intersection served as a comparison group. Trained observers recorded safety belt use rates (SBURs) of subjects (front seat occupants) over a two-week period at baseline and after a four-week period of intervention. Results were analyzed by chi-square comparisons of pre-treatment and post-treatment SBURs. At baseline, significant differences in SBURs between treatment groups were observed. Significant pre-to-post differences were found for TC3 and TC4: the SBUR in TC3 went from 18.3% - 38.4% (p less than 0.001) and the SBUR in TC4 went from 16.9% - 44.8% (p less than 0.001). Both TC3 and TC4 were effective, but TC4 cost 2.6 times more per person influenced to wear their safety belt.

Communication↗
PubMed1986

Prognostic factors in multiple myeloma.

All patients with multiple myeloma seen over a 9-year period at Tygerberg Hospital were studied retrospectively. Presentation data of 144 patients, as well as individual laboratory results were included in the survival analysis. Cox's proportional hazard model (a non-parametric multivariate regression method) was used to predict survival and divide patients into prognostic groups. The relationship between pairs of variables at the time of diagnosis was investigated. The survival of groups of patients was compared using the generalized Wilcoxon and Savage tests. The association of the following factors with prognosis were again substantiated: haemoglobin; serum creatinine, urea and albumin; percentage of plasma cells in the bone marrow aspirate and trephine biopsy specimen; and the number of lytic lesions on skeletal radiography. The following factors were not substantiated: serum uric acid, light-chain proteinuria, age at presentation of the disease and IgG rather than the IgA class. In addition, a higher serum monoclonal peak size at presentation of the disease, and a more rapid fall in the abnormal serum monoclonal peak within the first 40 days after commencing treatment were associated with a significantly longer survival.

Creatinine↗
PubMed1985

Primary pediatric care. A comparison of use by adolescent and older mothers.

This survey compares the use of pediatric services during the first year of life by infants whose mothers were under 17 years of age with a random sample of babies born during the same period and at the same hospital but to older mothers. Both sets of mothers were found to have similar patterns of acute and well-child care. For adolescent mothers, use of a group practice emphasizing provider continuity significantly increased well-child visits and immunizations. The adolescent mother's late entry into prenatal care appeared to be related to a greater use of the emergency room and to inadequate well-child care. The existence of a sibling was related to inadequate well-child care for adolescents' babies but to improved levels of well-child care among older mothers' babies. These findings suggest that close monitoring of adolescent mothers with more than one child may improve the quality of medical care for their infants.

Adolescent↗
PubMed1984

[Multiple myeloma in South Africa--is the incidence increasing?].

Multiple myeloma was once thought to be extremely rare, with an estimated frequency of less than 0,1% of all malignant tumours. In 1964 Oettlé reported that available mortality statistics showed 171 deaths in the 10-year period 1949-1958 in the RSA for Whites, Coloureds and Asiatics aged 20 years and older. During the 5-year period 1968-1972, however, 222 cases of multiple myeloma appeared in the mortality records of the Central Statistical Service. Since 1964 150 new cases have been diagnosed at Karl Bremer Hospital and later at Tygerberg Hospital, with an average of 15 new cases cases per year from 1978 to 1982. Four examples of familial myelomatosis and one of familial macroglobulinaemia were found at these two hospitals. On 1 January 1983, 48 patients were on record who had attended the Tygerberg Hospital Haematology Clinic and 78 who had attended Groote Schuur Hospital, giving a total of 126 patients under treatment in the Western Cape during 1982. In addition, for the 6-year period from January 1971 to December 1976, 162 patients were reported from the haematology clinics at the Johannesburg General Hospital and Baragwanath Hospital. The true incidence of multiple myeloma in the RSA is problematical because there is no National Cancer Register; establishment of such a register would need the co-operation of all doctors in the country.

Adult↗
PubMed1983

Evaluating continuity of care in primary care internal medicine programs.

One goal of primary care training programs is to provide "continuity experiences" for residents. Although programs funded by the Health Resources Administration are mandated to provide and evaluate such experiences, a wide variety may exist in both the concept and the evaluation of continuity in these training programs. To investigate methods for evaluating this continuity experience, we surveyed 52 federally funded primary care internal medicine programs using a checklist of methods derived from the literature. Of the programs surveyed, 64% responded and all but two were evaluating continuity, most of them using several methods. Although it might be assumed that most programs would be assessing continuity in the ambulatory setting, most reported that "residents followed up assigned patients when admitted to the hospital." Assessment of continuity in the ambulatory setting, by determining the number of times the patient was seen by his assigned resident divided by total outpatient visits, ranked fourth behind "missed appointments" and "medical record audits." "Percentage of emergency room visits by assigned patients" was least frequently cited.

Ambulatory Care↗
PubMed1982

Serum ferritin and mean corpuscular volume as predictors of bone marrow iron stores.

The prognostic value of serum ferritin (SF) as a predictor of bone marrow iron stores (BMS) was evaluated in an attempt to use SF and other readily available clinical and laboratory parameters in the more accurate prediction of BMS without bone marrow aspiration. The results of routine haematological studies of 1000 patients referred for a bone marrow examination as part of their diagnostic evaluation at Tygerberg Hospital were statistically analysed. Significant associations were found. The CHAID programme of automatic interaction detection as developed by Kass was used to determine the optimum classification. A statistical model in the form of a dendrogram has been computed for this hospital population and this laboratory for future predictions of BMS using only the values for SF and mean corpuscular volume. The predictions were statistically very highly significant, especially in patients with iron deficiencies.

Anemia↗
PubMed1981

Platelet antibodies in immune thrombocytopenic purpura and onyalai.

A prospective study was undertaken to assess the nature, incidence and natural history of platelet antibodies in patients with immune thrombocytopenic purpura (ITP) and patients with onyalai, using an immunofluorescent technique. Twelve patients under 14 years old and 11 patients 14-75 years old with ITP, and 24 patients with onyalai were studied. Alternate younger patients were treated with corticosteroids. Ten of the 12 children with ITP had IgG platelet antibodies in their serum, which disappeared as the platelet count recovered. Steroid therapy did not change the course of the disease or the antibody response. Of the 24 patients with onyalai, 23 had IgG antibodies and 18 had IgM antibodies, which were still present after 14 days and unrelated to their rise in platelet count. Steroid therapy did not affect the platelet count or the antibody titre. The difference in immune response of ITP and onyalai points to a difference in aetiology. The clinical presence of IgM antibodies in onyalai fits the hypothesis that a toxin, possibly acting as a hapten, is responsible for this form of thrombocytopenia.

Adolescent↗
PubMed1981

The new morbidity: use of school and community health care resources for behavioral, educational, and social-family problems.

The extent of the use of services for the new morbidity, that is, children's behavioral, educational, and family-social problems, has not previously been the subject of a community-based prospective study. The demographic characteristics and utilization of school and community health care resources over a two-year period are compared for two groups selected from a random sample (n = 671) of elementary school children. Twenty-four percent (n = 164) were observed to have behavioral, educational, or social-family problems requiring attention or intervention by health or educational personnel. This group was compared to their schoolmates (n = 507) not so identified. Although no overall differences in sex, ethnic background, or family structure were identified, the children with new morbidity problems were more frequently in the lowest socioeconomic group, and had lower reading achievement scores and higher rates of absenteeism. The new morbidity group also has higher rates of utilization of services both at school and at community sites of health care, not only for new morbidity complaints, but for other problems as well. The data suggest that this portion of the school-aged population places a significant demand for health care resources on both community and school sites. The findings support the need for training of physicians in the care and prevention of such problems.

Child↗