Biomedical subjects

A Kruger

Publications and source records attributed to A Kruger.

At least 19 recordsLinked to original sources

PubMed2006

Laser Doppler flowmetry detection of endothelial dysfunction in end-stage renal disease patients: correlation with cardiovascular risk.

Prediction of cardiovascular (CV) complications represents the Achilles' heel of end-stage renal disease. Surrogate markers of endothelial dysfunction have been advocated as predictors of CV risk in this cohort of patients. We have recently adapted a noninvasive laser Doppler flowmetry (LDF) functional testing of endothelium-dependent microvascular reactivity and demonstrated that end-stage renal disease patients are characterized by profound alterations in thermal hyperemic responsiveness. We hypothesized that such functional assessment of the cutaneous microcirculation may offer a valid, noninvasive test of the severity of endothelial dysfunction and CV risk. To test this hypothesis, we performed a cross-sectional study, in which we compared LDF measurements to conventional risk factors, and performed a pilot longitudinal study. LDF studies were performed in 70 patients and 33 controls. Framingham and Cardiorisk scores were near equivalent for low-risk patients, but more divergent as risk increased. C reactive protein (CRP) levels and LDF parameters (amplitude of thermal hyperemia (TH), area under the curve of TH) showed significant abnormality in high-risk vs low-risk patients calculated using either Framingham or Cardiorisk scores. Patients who had abnormal LDF parameters showed increased CV mortality, however, had similar risk assessments (Framingham, Cardiorisk, CRP, and homocysteine) to those with unimpaired LDF tracings. In conclusion, LDF parameters of microvascular reactivity offer a sensitive characterization of endothelial dysfunction, which may improve CV risk assessment through incorporation into the Framingham or Cardiorisk algorithm.

Adult↗

PubMed2006

Predictors of South African male testosterone levels: the THUSA study.

The process of urbanization occurring in many developing countries may have consequences for reproductive endocrine function. Here, we test predictions concerning variation in South African male testosterone levels among subgroups across an urbanization gradient representing differences in both geography and socioeconomic status. Subjects included 364 males aged between 20 and 82 comprising a cross-sectional study conducted between 1996 and 1998. Testosterone levels were measured from serum samples obtained between 08:00 and 11:00. In ANCOVA analysis, male testosterone levels differed significantly along this rural-to-urban gradient, with members of the most urban group having higher testosterone levels than groups of farmers and inhabitants of informal housing areas adjacent to towns. Testosterone levels declined with age and were negatively related to body mass index (BMI). Testosterone levels did not differ according to HIV status. Further exploratory ANCOVA analyses revealed that physical activity levels, depression, affect, and hostility were not significantly associated with variation in testosterone levels. These data help document causes of variation in male testosterone levels in a context of urbanization and may have implications for clinical outcomes such as the development of a male hormonal contraceptive or prostate cancer.

Adult↗

PubMed2006

Poverty and household food security of black South African farm workers: the legacy of social inequalities.

OBJECTIVE: To assess socio-economic indicators, nutritional status and living conditions of farm workers and their families, with the purpose to develop research and intervention programmes aimed at enhancing nutritional status and quality of life. DESIGN AND SETTING: Three farm schools in two districts of the North-West Province and farming communities were selected. Anthropometrical measurements, structured face-to-face questionnaires and focus group discussions were carried out in 2002 and 2003 by a multidisciplinary research team. RESULTS: Access to electricity, water and sanitation, as well as monthly food rations or subsidies, vary and depend on farm owners. The majority of adults have education below or up to grade four, farm schools provide only up to grade seven. Distance to farm schools and intra-household issues hamper children's attendance and performance at school. Household food security is compromised due to a lack of financial resources, infrastructure and also household resource allocation. This impacts negatively especially on children, with half of them being underweight, stunted or wasted. Employment is usually linked to men, while most women have access to casual jobs only. Insecurity of residence and the perceived disempowered position towards farm owners add to feelings of hopelessness and stress. CONCLUSIONS AND RECOMMENDATIONS: This study highlights destitute living conditions of farm worker families. Apart from structural and financial constraints, paternalistic structures of the past might also hamper development. Based on these findings, follow-up research projects and in-depth investigations into underlying social issues with regard to nutrition insecurity and livelihoods of farm workers were initiated.

Adolescent↗

PubMed2006

The influence of testosterone on blood pressure and risk factors for cardiovascular disease in a black South African population.

OBJECTIVES: Traditionally high testosterone levels have been thought to have a detrimental effect on lipid profiles. Recently, reports have shown that testosterone has a beneficial effect on lipid profiles. On the other hand, androgens may increase blood pressure via the renin-angiotensin system. The aim of this study was to determine whether the level of testosterone is increased in hypertensive subjects or if other cardiovascular risk factors are altered with increased levels of testosterone in the Black population of South Africa. METHODS: For this study, 536 male and 666 female Black subjects were included. The subjects were divided into hypertensive and normotensive groups and high and low testosterone groups. Resting blood pressure was recorded with a finger arterial pressure device. Blood sampling and biochemical analyses were done by using standardized methods. RESULTS: The levels of testosterone in the hypertensive males and females were significantly higher compared to the normotensives. In the male high testosterone group, the level of triglyceride was significantly lower, while the high-density lipoprotein cholesterol level was significantly higher. In the female high testosterone group, systolic blood pressure, cortisol level, and renin activity were significantly higher. CONCLUSION: In the males, we found beneficial effects of testosterone, which may explain the reported lower incidence of atheroma. However, the testosterone level is also higher with hypertension. The elevated levels of systolic blood pressure and renin activity that were found in the female group with high testosterone levels may be an indication of the role of the renin-angiotensin system in this regard.

Adult↗

PubMed2005

The transcriptional landscape of the mammalian genome.

This study describes comprehensive polling of transcription start and termination sites and analysis of previously unidentified full-length complementary DNAs derived from the mouse genome. We identify the 5' and 3' boundaries of 181,047 transcripts with extensive variation in transcripts arising from alternative promoter usage, splicing, and polyadenylation. There are 16,247 new mouse protein-coding transcripts, including 5154 encoding previously unidentified proteins. Genomic mapping of the transcriptome reveals transcriptional forests, with overlapping transcription on both strands, separated by deserts in which few transcripts are observed. The data provide a comprehensive platform for the comparative analysis of mammalian transcriptional regulation in differentiation and development.

3' Untranslated Regions↗

PubMed2005

Existing delays following the presentation of ruptured abdominal aortic aneurysm allow sufficient time to assess patients for endovascular repair.

OBJECTIVES: The greatest benefit of endovascular AAA repair (EVAR) may be in the management of rupture (RAAA). However, the detailed anatomical assessment required for EVAR has lead to concerns of surgical delay and death during cross-sectional imaging. In this study, we prospectively assessed patients with RAAA and correlated time of hospital arrival with time of surgery or death to ascertain whether these concerns are justified. METHODS: All patients presenting with RAAA between October 2000 and December 2002 were included. The hospital arrival time, onset of surgery or time of death, were recorded, as were demographic and physiological parameters. RESULTS: One hundred consecutive patients were studied, median age 75 years (range 54-94). Seventy-nine patients underwent attempted conventional surgical repair and 21 were palliated. The median delay from arrival to operation was 159 min (range 16-1450 min). Mortality in the surgical group was not affected by the length of delay (p = 1.0) or by CT scanning (p = 0.34). The median time from arrival to death in the non-surgical group was 435 min (15 min-6 days). CONCLUSIONS: Most patients who present with ruptured AAA experience a significant delay prior to surgery. This study suggests it is safe to assess the majority of RAAA patients for EVAR.

Aged↗

PubMed2005

Hepatitis B surface antigen presentation and HLA-DRB1*- lessons from twins and peptide binding studies.

The aim of this study was to investigate the underlying mechanisms of the genetic association between certain HLA-DRB1* alleles and the immune response to HBsAg vaccination. Therefore, HBsAg peptide binding to HLA-DR molecules was measured in vitro by peptide binding ELISAs. Additionally, HBsAg-specific T cell reaction and cytokine profile of immune response were analysed ex vivo in ELISPOT assays and DR-restriction of T-cell proliferative responses was investigated with HBsAg specific T cell clones. In addition, we compared HBsAg specific T cell responses of 24 monozygotic and 3 dizygotic twin pairs after HBsAg vaccination. Our results showed that the peptide binding assays did not reflect antigen presentation in vivo. DR alleles associated with vaccination failure like DRB1*0301 and 0701 efficiently presented HBsAg peptides. In 11 of 24 investigated monozygotic twin pairs we observed pronounced differences in the recognition of HBsAg peptides. This study indicates that HLA-DR associations with HBsAg vaccination response are not caused by differences in peptide binding or by a shift in the Th1/Th2 profile. Our findings strongly argue for differences in the T cell recognition of peptide/MHC complexes as the critical event in T cell responsiveness to HBsAg.

Adolescent↗

PubMed2002

Differential regulation of interleukin-10 production by genetic and environmental factors--a twin study.

Interleukin-10 (IL-10) has a critical role in the regulation of immune responses. The relative contribution of genetic and environmental factors to IL-10 production is under debate. We performed a twin study in 246 monozygotic and dizygotic twins to assess the heritability of IL-10 production after LPS stimulation in whole blood. In addition, the influence of promoter single nucleotide polymorphisms (-1082, -819 and -592) on transcriptional activity and their binding to nuclear factors was studied in luciferase reporter gene and electrophoretic mobility shift assays. IL-10 production showed a genetic determination with a heritability of 0.5. Decreasing body mass index (BMI), smoking and female gender lead to decreased IL-10 production. In monocytes, the -1082A allele showed higher binding affinity to the transcription factor PU.1 resulting in decreased transcriptional activity of -1082A promoter haplotypes. Genetic determination of IL-10 secretion is probably lower than that previously reported. Fifty percent of the observed variability explained by genetic factors. Female individuals produce less IL-10 than male subjects. Environmental factors like smoking and decreasing BMI exert suppressing effects on IL-10 production. Although the -1082A allele shows higher binding affinity to the PU.1 transcription factor and lower transcriptional activity, this polymorphism probably explains only a small fraction of the observed heritability.

Binding Sites↗

PubMed2002

Impact of urbanisation on serum lipid profiles--the THUSA survey.

OBJECTIVE: To examine the impact of urbanisation on lipid profiles of black South Africans, stratified for HIV status. DESIGN: Cross-sectional population-based survey. SETTING: North West province of South Africa. SUBJECTS: A representative sample of 1,854 apparently healthy volunteers aged > or = 15 years, was recruited from 37 randomly selected sites throughout the province. Subjects were stratified into five urbanisation strata (S): S1 rural villages, S2 farms, S3 informal housing or 'squatter camps' S4 urban townships, and S5 surburban housing. OUTCOME MEASURES: Demographic, physical activity and dietary intake information was collected using validated and culture-sensitive questionnaires. Anthropometric measurements and lipid analyses were determined using standardised methodology. RESULTS: The results revealed significantly lower mean (95% confidence interval) total serum cholesterol (TC) levels in HIV-negative men in S1-S4 compared with S5 (S1 3.91 (3.77-4.05) v. S5 4.79 (4.54-5.04) mmol/l). In HIV-negative women, TC levels were significantly lower in S1-S3 than in S4 and S5 (S1 4.05 (3.94-4.17) v. S5 4.79 (4.59-5.00) mmol/l). The same trends were seen for serum low-density lipoprotein cholesterol (LDLC) and triglycerides and in HIV-positive subjects. Binary logistical analysis indicated that the main factor responsible for the increased TC levels seemed to be increased body mass index (BMI) due to decreased physical activity. CONCLUSIONS: Serum lipid levels increased with urbanisation although they remained within levels recommended for other populations. This may, however, become an important health problem in future if preventive strategies are not implemented. Culturally sensitive physical activity programmes to decrease BMI, targeted at professional men and women, and women in urban townships, seem to constitute the most appropriate intervention.

Adult↗

PubMed2001

Lens epithelial cell outgrowth on 3 types of intraocular lenses.

PURPOSE: To compare the outgrowth of lens epithelial cells (LECs) on 3 types of intraocular lenses (IOLs) to determine the influence of lens material and lens design (optic edge) on this phenomenon. SETTING: Department of Ophthalmology, University of Vienna, Medical School, Vienna, Austria. METHOD: Ninety eyes scheduled for cataract surgery were included in a prospective comparative study. A standardized surgical procedure was performed by 1 experienced surgeon. Patients received 1 of 3 types of posterior chamber IOLs of similar design with a 6.0 mm optic and poly(methyl methacrylate) haptic: AcrySof (Alcon), HydroView (Bausch & Lomb), or Sensar (Allergan). Each IOL type was implanted in 30 eyes. Postoperative biomicroscopic examinations were performed 1, 3, 7, 30, 90, and 180 days and 1 year after surgery. Lens epithelial cells in each quadrant of the anterior lens surface were subjectively graded. The product with the highest density and the number of quadrants with this density were used to measure LEC outgrowth. RESULTS: Statistically significant differences (P <.05) were seen between the hydrophilic IOL and the 2 hydrophobic lenses from day 30 until the final examination. The HydroView lens had a higher number of LECs on its anterior surface than the AcrySof or Sensar IOL. There were no statistically significant differences between the 2 acrylic IOLs at any measurement. CONCLUSION: The findings suggest that lens surface properties have a greater influence on LEC outgrowth than lens design (ie, sharp optic edge).

Acrylic Resins↗

PubMed2001

Cellular reaction on the anterior surface of 4 types of intraocular lenses.

PURPOSE: To assess the cellular reaction on the anterior surface of 4 types of foldable intraocular lenses (IOLs). SETTING: Department of Ophthalmology, University Hospital of Vienna, Vienna, Austria. METHODS: One hundred eyes scheduled for cataract surgery were prospectively randomized into 4 groups of 25 eyes each using random number tables. Group 1 received a Hydroview IOL (Bausch & Lomb), Group 2 an AcrySof IOL (Alcon), Group 3 a MemoryLens IOL (ORC), and Group 4 a CeeOn 920 IOL (Pharmacia). Patients were examined 1, 3, 7, 30, 90, and 180 days postoperatively. Postoperative biomicroscopic examinations were done with a slitlamp, and a specular microscope was used to document the presence of cell deposits and identify areas with the highest density of cells. RESULTS: The local tissue response revealed 2 patterns: a nonspecific foreign-body reaction to the IOL (small round, fibroblast-like, epithelioid, and giant cells) and a lens epithelial cell (LEC) reaction. The highest incidence of LECs was in the Hydroview group, in which LECs were present on 81.8% of lenses 180 days postoperatively. During the first postoperative days, small round and fibroblast-like cells were found on all IOLs. From 7 days on, the incidence and density of these cells were less severe in the Hydroview and CeeOn 920 groups. After several weeks, epithelioid cells and foreign-body giant cells were seen on some IOLs. These cells appeared more often on AcrySof, MemoryLens, and CeeOn IOLs. CONCLUSION: This study found IOL-related differences in cellular reaction after cataract surgery. The incidence of a nonspecific foreign-body reaction to 4 IOLs is consistent with the results of previous studies. The incidence of LECs was highest in the Hydroview group and lowest in the AcrySof group. The CeeOn 920 group had the lowest incidence of all types of cells.

Aged↗

PubMed2001

Comparison of the biocompatibility of 2 foldable intraocular lenses with sharp optic edges.

PURPOSE: To compare the clinical performance of 2 foldable intraocular lenses (IOLs) with sharp optic edges in terms of uveal and capsular biocompatibility. SETTING: Department of Ophthalmology, University Hospital of Vienna, Vienna, Austria. METHODS: Fifty eyes scheduled for cataract surgery were included in this comparative study. A standardized surgical protocol was used, and all operations were performed by 1 experienced surgeon. Two posterior chamber lens types of similar design with a 6.0 mm sharp-edged optic and poly(methyl methacrylate) haptics were used. Twenty-five eyes received an AcrySof acrylic IOL (Alcon), and 25 eyes received a CeeOn 911A silicone IOL (Pharmacia). Relevant data were collected at a 3-year follow-up examination. To evaluate uveal biocompatibility, anterior chamber laser flare and cell measurements and inflammatory cell reactions were monitored. Cellular biocompatibility was investigated by examining anterior capsule opacification (ACO), posterior capsule opacification (PCO), and lens epithelial cell (LEC) ongrowth on the IOL's anterior surface. Factors such as intralenticular glistenings and IOL decentration were also evaluated. RESULTS: Anterior chamber flare and cells and the inflammatory cell reaction were significantly lower in the CeeOn 911A group. There was no statistically significant difference in ACO, PCO, and LEC ongrowth between the 2 groups. The AcrySof lenses showed significantly better centration and a higher density of intralenticular glistening. CONCLUSIONS: The findings show that a sharp-edged optic design is, to date, the most effective method of reducing the rate of PCO. Despite a subclinical foreign-body reaction in the AcrySof group, both lenses had a high degree of capsular and uveal biocompatibility.

Acrylic Resins↗

PubMed2001

Sequence analysis of the DRB1 promoter reveals limited polymorphism with no influence on gene expression.

HLA-class II promoters contain a set of conserved regulatory regions necessary for constitutive and induced gene expression. For the HLA-DQB as well as for the DRB1 promoter sequence, polymorphisms with influence on gene expression have been reported. In contrast to these data we could show that there is very limited allele-specific polymorphism among the HLA-DRB1 promoter alleles. In a long range PCR we amplified a DNA sequence containing the promoter and the second exon of the DRB1 gene in one fragment. Nested PCR products of this PCR fragment for the promoter and for the second exon were analysed by DNA sequencing to allow the linkage of a promoter to its DR allele. Most investigated DRB1 alleles exhibited the same promoter consensus sequence except for two point mutations. An A to T transversion (position -70 bp) was closely associated with DRB1*08, whereas a C-deletion (position -30 bp) was most commonly observed together with DRB1*10. Both polymorphisms did not influence promoter activity in luciferase reporter gene assays.

Base Sequence↗

PubMed2001

Outcome after silicone oil removal.

BACKGROUND: Combined with vitreoretinal surgery, silicone oil injection has become a standard technique and improves the prognosis of complex retinal detachment. As silicone oil leads to long term complications, removal of silicone oil from the eye is recommended. To evaluate the outcome after silicone oil removal, retinal redetachment, visual acuity, and complications were analysed. METHODS: The authors analysed 115 consecutive cases of silicone oil removal (115 eyes), all operated by one surgeon. The series consisted of retinal detachments associated with proliferative vitreoretinopathy (103 eyes), proliferative diabetic retinopathy (six eyes), or ocular trauma (six eyes). The mean duration of intraocular silicone oil tamponade was 13.3 months, with a mean postoperative follow up of 1.8 years. RESULTS: Anatomic success after silicone oil removal, defined as a complete retinal attachment, was achieved in 95 of 115 eyes (82.6%). Redetachment occurred in 20 eyes (17.4%), mostly within the first 6 months after silicone oil removal. Including the successfully reoperated eyes, the authors present a final anatomic success rate of 108 eyes (93.9%). Visual acuity improved or remained unchanged in 93 eyes (80.9%). CONCLUSION: While reattachment and complication rates were quite similar to other studies, a better visual outcome was achieved in these cases. The duration of the silicone oil tamponade had no significant effect on the reattachment rate. The authors recommend not to apply standard criteria for the timing of silicone oil removal, but to decide individually, considering the underlying disease, as well as the previous operations.

Adolescent↗

PubMed2001

Military social work in the South African National Defence Force.

The transformation of the South African National Defence Force has prompted a critical reassessment of the Directorate of Social Work. As a result, the directorate realized the need for a formal business plan to align the profession strategically with the core business of the military system. After completion of the business plan, the need for a unique military social work practice model was identified. Such a model should present social workers with a strategy for the achievement of the goals and objectives of the business plan. The practice model rests on two key concepts: binocular vision and practice positions. Since the onset of the transformation process in the South African National Defence Force, these two documents have reflected the changing milieu within which social work is practiced. The main concepts of these documents are presented.

Humans↗

PubMed2000

Effect of tropicamide on aqueous flare before and after cataract surgery.

PURPOSE: To examine the effect of tropicamide on flare intensity under phakic and pseudophakic conditions and to differentiate between the possible mechanisms of action of tropicamide on aqueous flare. SETTING: Department of Ophthalmology, Vienna General Hospital, University of Vienna, Vienna, Austria. METHODS: In this prospective study, aqueous flare was measured with the laser flare-cell meter in 20 eyes of 20 patients with age-related cataract enrolled for cataract surgery. Measurements were performed before and 30, 90, and 180 minutes after pupil dilation with tropicamide 0.5%. This measurement was performed in the phakic eye on the day before surgery and in the pseudophakic eye on postoperative days 1, 3, 7, and 28. RESULTS: After tropicamide instillation, aqueous flare decreased preoperatively and on all postoperative days. There was a continuous flare decrease until 3 hours after instillation, reaching a maximum decrease of about 30%. Pupil diameter reached its maximum after 30 minutes. CONCLUSION: Tropicamide significantly decreased aqueous flare, seemingly by pharmacological means, not volumetric changes. The time between drug application and measurement should be kept constant.

Aged↗

PubMed2000

Long-term disorders of the blood-aqueous barrier after small-incision cataract surgery.

PURPOSE: To determine the long-term function of the blood-aqueous barrier after small-incision cataract surgery with implantation of a foldable intraocular lens. METHODS: The blood-aqueous barrier function in 74 eyes of 62 patients who underwent cataract surgery was examined using a laser flare-cell meter. The measurements were performed pre-operatively and post-operatively between 12 and 35 months after surgery. For statistical analysis a linear regression was used. The study was designed as a single cohort study, with comparison of pre- and post-operative values. RESULTS: Highly statistically significant differences (p < 0.0001) were found between pre-operative flare values and those measured at the final visit. The linear regression model showed significantly higher flare values post-operatively compared with those measured pre-operatively. Other variables such as incision technique, sex, operation time, phaco time and systemic disease had no influence on this outcome. CONCLUSION: The results suggest that there is persistent blood-aqueous barrier dysregulation even several years after cataract surgery.

Aged↗

PubMed2000

[Postoperative inflammatory response to phacoemulsification and implantation of 2 types of foldable intraocular lenses in pseudoexfoliation syndrome].

BACKGROUND: Patients with pseudoexfoliation syndrome (PEX) are known to have a greater degree of inflammation after cataract surgery when compared to patients with senile cataract in otherwise healthy eyes. We performed a randomised, prospective study to compare the influence of the intra-ocular lens (IOL) material of two different IOLs on the postoperative inflammation of the anterior chamber. PATIENTS AND METHODS: 28 eyes of 27 patients with PEX and cataract and 29 eyes of 29 control patients were included in this study. The IOLs used were the hydrophilic, acrylic lens: Bausch&Lomb-Hydroview and the hydrophobic, acrylic Alcon Acrysof MA60 lens. The patients were examined preoperatively as well as on day 1, 3, 7 and 1, 3, and 6 months after surgery using the Laser flare-cell meter (LFCM) KOWA FC 1000. RESULTS: The preoperative flare and cell values were significantly higher in PEX eyes as compared to the control group. The values decreased after about 1 month to reach values comparable to those in the control group. Over the six months period there was no significant difference between the values of both lenses in the PEX group except on the first postoperative day where the flare and cell values were higher in the Acrysof-lens group. When comparing both groups with the Hydroview-lens there was also no significant difference, except on day 7, between the PEX group and the control group up to 6 months after surgery. When comparing both groups with the Acrysof-lens, there was a significant difference between the PEX group and the control group until 1 month after surgery. CONCLUSION: Although PEX-eyes had higher flare and cell values up to one month after surgery, we could not determine a significant difference, except on the first postoperative day, between both IOLs. A significant difference was evident between the PEX and control group in eyes with an Acrysof-lens. Using this clinical model, the LFCM highlights only certain aspects of biocompatibility of different lens types.

Acute-Phase Reaction↗