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Biomedical subjects

A Bergström

Publications and source records attributed to A Bergström.

At least 19 recordsLinked to original sources
PubMed1999

Occupational physical activity and renal cell cancer: a nationwide cohort study in Sweden.

The causes of renal cell cancer remain incompletely understood. In one previous retrospective case-control study, high occupational physical activity has been associated with a decreased risk among men, but not among women. Our aim was to investigate the association between occupational physical activity and renal cell cancer in a large cohort in Sweden. A cohort of Swedish men and women was identified in the nationwide censuses in 1960 and 1970, and the reported occupations were classified into 4 levels of physical demands. Follow-up from 1971 through 1989 was accomplished through record linkages to the Swedish Cancer Registry. Multivariate Poisson regression models were used to estimate relative risk (RR) and 95% confidence intervals (CI). We found a monotonic increase in risk of renal cell cancer with decreasing level of occupational physical activity among men (p for trend <0.001). After adjustment for socio-economic status, place of residence, and calendar year of follow-up, men with long-term sedentary jobs had a 25% (RR = 1.25, 95% CI 1.02-1.53) increased risk compared to men with physically demanding occupations. Among women there was no association, the dose-risk trend was not significant (p for trend >0.50). Occupational physical activity was inversely associated with renal cell cancer among men. The absence of association among women might be due to smaller range of exposure, confounding by household work or reproductive factors, or to a difference in biological response to physical activity in men and women.

Adult↗
PubMed1999

The role of diabetes mellitus in the aetiology of renal cell cancer.

To investigate the relation between diabetes mellitus and the risk of renal cell cancer we carried out a population-based retrospective cohort study. Patients identified in the Swedish Inpatient Register who were discharged from hospitals with a diagnosis of diabetes mellitus between 1965 and 1983 formed a cohort of 153852 patients (80005 women and 73847 men). The cohort members were followed up to 1989 by record linkage to three nation-wide registries. Standardized incidence ratios (SIRs) and standardized mortality ratios (SMRs) were computed using age-specific sex-specific and period-specific incidence and mortality rates derived from the entire Swedish population. After exclusion of the first year of observation, a total of 267 incidences of renal cell cancer (ICD-7:180.0) occurred in diabetic patients compared with the 182.4 that had been expected. Increased risks were observed in both women (SIR = 1.7, 95% confidence interval, CI = 1.4-2.0) and men (SIR = 1.3; 95 % CI = 1.1-1.6) throughout the duration of follow-up (1-25 years). A higher risk was seen for kidney cancer (ICD-7:180) mortality (SMR = 1.9; 95% CI = 1.7-2.2, women; SMR 1.7, 95% CI = 1.4-1.9, men). In comparison with the general population, patients with diabetes mellitus have an increased risk of renal cell cancer.

Age Factors↗
PubMed1999

Longitudinal changes in visual acuity and visual ability in a cohort followed from the age of 70 to 88 years.

PURPOSE: To assess the change in visual acuity (VA) for distance and near and to correlate VA to changes in visual ability in a longitudinal study group followed from 70 to 88 years. METHODS: In the population-based study H70 in Gothenburg, Sweden, 958 subjects from the original cohort were eye examined at age 70 and the surviving subjects were reexamined at age 82 (n=203) and at 88 years (n=129). Evaluation of change in visual function between age 82 and 88 was made in 66 subjects who took part in all three eye examinations. RESULTS: The VA in the subsample (n=66) showed minimal difference compared to the cross-sectional groups. At age 70 nearly 100% of both sexes had VA> or =0.8. At age 82 about 50% and at age 88 about 25% had this VA level. Males retained a slightly better visual acuity compared to women. VA< or =0.3 was found in about 10% at age 82 and in >20% at age 88. Reading ability remained high, but at 82 years 1.6% and at 88 years 10.5% could benefit from adjustment of their near glasses. Visual ability corresponded well to VA at age 82, but not at 88 years. Women lost the ability for most tasks, whereas men showed small changes. CONCLUSIONS: The majority of old people had good distance and near vision. A deterioration in visual acuity did not necessarily mean a negative change in visual ability. This emphasizes the importance of relating objective and subjective findings regarding VA and visual impairment to functional ability of the oldest of the elderly.

Activities of Daily Living↗
PubMed1998

Response rate to mailed epidemiologic questionnaires: a population-based randomized trial of variations in design and mailing routines.

Although self-administered questionnaires are major sources of information in epidemiology, comparatively little has been done to study practical aspects of design and mailing. The objective of this study was to evaluate various measures taken to increase the response rate. A questionnaire was mailed in July 1995 to a random sample (n = 2,000) of the Swedish population aged 20-79 years. Using a randomized factorial study design, the questionnaire and mailing procedures were changed in three ways: preliminary notification, length of the questionnaire, and mention of telephone contact. The overall questionnaire retrieval rate was 49%. Preliminary notification (adjusted odds ratio of receiving a completed questionnaire = 1.30, 95% confidence interval (CI) 1.08-1.56 relative to the absence of preliminary notification) and short length of the questionnaire (odds ratio = 1.24, 95% CI 1.04-1.48 relative to a long questionnaire) were both independently associated with a higher retrieval rate. Of eight possible combinations, the one comprising preliminary notification, a short questionnaire, and no mention of telephone contact gave the highest retrieval rate, 56%. The lowest retrieval rate, 40%, was observed for the combination of no preliminary notification, a long questionnaire, and mention of telephone contact. Young age, male sex, and urban residence significantly lowered the retrieval rate. Although there was a positive association between the questionnaire retrieval rate and partial nonresponse (missing answers in retrieved questionnaires), the marginal losses due to the latter did not cancel the gains by optimized mailing routines. Old age was the strongest determinant of partial nonresponse. The data provide evidence that design and mailing strategies, as well as demographic characteristics, may greatly influence the response rate of mailed epidemiologic questionnaires.

Adult↗
PubMed1998

Immediate assessment of HbA1c under field conditions in Tanzania.

In Tanzania, assessment of blood glucose is the most frequently used method for evaluating glycaemic control in diabetic patients. The patients' metabolic control is often poor and the determination of glycated haemoglobin (HbA1c) for long-term control could be a valuable tool to better manage the treatment. The aim of this study was to determine whether an immediate assessment method for HbA1c (DCA 2000 analyzer) gives reliable results in the warm and moist climate of east Africa. The study was performed in two parts. One equipment test in Sweden where blood samples from 65 diabetic patients were analysed in a DCA 2000 kept at room temperature and in another kept in a climate chamber. The samples were also analysed with HPLC as a reference method. In the second part HbA1c was analysed in 159 Tanzanian diabetic patients with a DCA 2000 and with HPLC combined with a filter paper technique (HbA1c via Post). The study showed that the DCA 2000 gives reliable results at 85% humidity and a temperature not exceeding +31 degrees C. The correlation with the HPLC analysis varied between 0.94 and 0.98. The conclusion is that the DCA 2000 analyzer can be used in Tanzania during the winter but has to be placed in an air-conditioned room if the temperature exceeds +31 degrees C.

Adult↗
PubMed1998

Confirmation of nosocomial transmission of hepatitis C virus by phylogenetic analysis of the NS5-B region.

Four hepatitis C virus transmission chains at three dialysis units were disclosed by limited sequencing; three of these were disclosed by analysis of the NS5-B region of the genome. Dialysis on the same shift as that during which infected patients were dialyzed was the common factor for seven patients in two chains. Two nurses exposed to needle sticks and their sources of infection constituted two other chains. The strains of three chains belonged to subtype 1a and formed clusters with an intrachain variability of 0 to 6 nucleotides compared to 8 to 37 nucleotides for unrelated strains within this subtype. The clusters were supported by bootstrap values ranging from 89 to 100%.

Cross Infection↗
PubMed1997

Outcome of clinical foot examination in relation to self-perceived health and glycaemic control in a group of urban Tanzanian diabetic patients.

Diabetic foot complications were studied in 153 patients at the university clinic in Dar es Salaam (56 insulin treated, 77 treated with oral agents and 20 with diet only). Neuropathy disability and symptoms scores were used to diagnose peripheral neuropathy (PN). Peripheral vascular disease (PVD) was classified as ankle/brachial pressure index less than one. The degree of metabolic control was assessed by glycated haemoglobin (HbA1c) and self-perceived health was measured with SF-36. PN was present in 28.1% of patients and 12.5% had PVD. Patients with PN had higher age and later onset of diabetes in comparison with patients without food complications. Patients with PVD had longer duration of diabetes and higher systolic and diastolic blood pressure compared with those free from PVD. HBA1c and body mass index did not seem to influence the occurrence of PN or PVD. Patients with PN had significantly poorer self-perceived health, whilst PVD-patients had health scorings equal to patients without any foot complications. PN, but not PVD, appeared to have a negative influence on patients self-perceived health. In comparison with studies from the industrial world, foot problems are as common in diabetic patients living in a developing country.

Adult↗
PubMed1997

Influence of technique and transplantation site on rosette formation in rabbit retinal transplants.

In order to determine mechanical and host-graft related interactions in the histogenesis of retinal transplants, a new technique for transplanting flat and comparatively large pieces of embryonic rabbit retina into adult rabbit eyes was elaborated. With the procedure, free-floating grafts in the epiretinal space survive, develop and differentiate largely without rosette formation, suggesting that the dissection and transplantation procedure is adequate for obtaining a normal development. On the other hand, subretinal transplants mature at an apparently faster pace than epiretinal transplants, but do not become regularly laminated. Outer segments do not develop well in the epiretinal transplants, whereas they do so in the subretinal ones, suggesting host-graft interactions by means of yet unknown diffusible factors.

Animals↗
PubMed1997

High prevalence of GB virus C strains genetically related to strains with Asian origin in Nicaraguan hemophiliacs.

The presence of hepatitis GB virus C (GBV-C), also known as hepatitis G virus (HGV), and hepatitis C virus (HCV) were investigated in sera from 45 hemophiliacs from nine locations in Nicaragua using a nested polymerase chain reaction (PCR). Primers used to detect GBV-C and HCV derived from the helicase region and 5'UTR, respectively. Seventeen (38%) patients were positive for GBV-C RNA in serum by PCR. Twelve (27%) patients were positive for HCV RNA by PCR. Six (13%) of these were coinfected with GBV-C. Anti-HCV was detected in all the 12 HCV RNA positive hemophiliacs and in another 14 (31%) individuals, in whom GBV-C RNA was found in 2. Ten patients (22%) lacked markers for both GBV-C and HCV. The mean age of the patients positive for GBV-C but negative for HCV by PCR was significantly lower than for those negative for GBV-C but positive for HCV by PCR (P < 0.05; Student's t-test), indicating that the risk for this group of hemophiliacs to acquire GBV-C infection is higher as compared to the risk of acquiring HCV infection. Eleven GBV-C strains were sequenced in the 5'UTR. Sequence comparison to previously published GBV-C strains revealed that all 11 strains were more similar to Asian strains than to strains of European and African origin. Sequences in the NS5-B region were available for 8 HCV strains, all of which were found to belong to genotype 1a. The similarity of the Nicaraguan GBV-C strains to strains from Asia indicates that the GBV-C strains in the region presumably have an Amerindian origin. It is also considered that the HTLV II strains in the New World aboriginal populations are ancient and brought there by the ancestral Amerindian populations from Asia. Further, the genotype F of hepatitis B virus, known to represent the strains in populations with Amerindian background, predominates in Central American populations with Hispanic background. It remains to be clarified why Amerindian strains of GBV-C as well as of HBV predominate also in populations with mixed ethnic background in Central America.

Adolescent↗
PubMed1996

Comparisons of studies on diabetic complications hampered by differences in GHb measurements.

OBJECTIVE: To compare glycated hemoglobin (GHb) values of the relationship between glycemic control and complications of diabetes from laboratories involved in long-term studies (Steno, Oslo, Stockholm, Diabetes Control and Complications Trial, and Linköping.) RESEARCH DESIGN AND METHODS: Blood samples were collected from 25 subjects selected to represent the clinically relevant measurement range. Fresh whole-blood samples were distributed and analyzed within 4 days of sample collection. Pretreatment of samples and analyses of GHb were performed according to the routine method of each study's central or reference laboratory. Results from each laboratory were compared with the group mean, i.e., the mean of all results for each sample. RESULTS: Regression analyses with the group mean values as independent variables and results from each laboratory as dependent variables showed that Oslo's result had a slope significantly different from the group mean. Laboratories used by the DCCT, Oslo, and Steno studies gave, on average, 0.4, 0.4, and 0.7% higher HbA1c readings than the group mean, respectively, while HbA1c results from Linköping and Stockholm were, on average, 0.6 and 1.0% lower, respectively. CONCLUSIONS: There were large differences in GHb values among laboratories participating in studies of diabetic complications. The present data offer a guide to the comparison of results from the studies and underscores the need for standardization of GHb measurements.

Diabetes Complications↗
PubMed1995

The membrane glycoprotein G1 of Uukuniemi virus contains a signal for localization to the Golgi complex.

Members of the Bunyaviridae family acquire their envelopes by budding into the Golgi complex (GC). The accumulation of the membrane glycoproteins G1 and G2 in the GC probably determines the site of maturation. Here we have studied the intracellular transport and targeting to the GC of G1 and G2 of Uukuniemi virus, a member of the Phlebovirus genus, and report on their expression from cloned cDNAs either together or separately by using a T7 RNA polymerase-driven vaccinia virus expression system. When G1 and G2 were expressed together from a full-length cDNA as the p110 precursor, both proteins were localized to the Golgi complex, as evidenced by colocalization with the Golgi marker enzyme mannosidase II. Immunofluorescent staining indicated that G1 expressed alone also localized to the GC. However, pulse-chase experiments showed that G1 remained endoglycosidase H sensitive. G2 expressed alone remained associated with the endoplasmic reticulum (ER). G2 could be rescued from the ER and transported to the GC by coexpression with G1 from separate mRNAs. Coexpression also increased the efficiency of G1 transport to the GC. With none of the constructs could the glycoproteins be observed on the cell surface. These results show that efficient export of G1 and G2 from the ER requires coexpression of both proteins, in conformity with our previous results showing that G1 and G2 form heterodimeric complexes in the ER. Since G1 expressed alone is retained in the GC, we conclude that G1 contains a retention signal for localization to the GC. G2 might thus become associated with the GC indirectly via its interaction with G1.

Biological Transport↗
PubMed1995

Co-transplantation of embryonic retina and retinal pigment epithelial cells to rabbit retina.

The retinal pigment epithelium (RPE) is important for normal development of the neural retina. We sought to investigate whether cografting RPE cells affected the differentiation and survival of retinal grafts. Pigmented embryonic day 16 (E16) rabbit retina was dissected either with or without attached RPE and injected into a lesion site in retinas of young adult rabbit hosts. Each host obtained a pure retina graft in one eye and a retina/RPE cograft in the other. Animals were sacrificed after 4, 8 and 12 weeks. After 4 weeks, grafts (1-2 mm in diameter) were seen in both experimental groups at the lesion site or in the subretinal space. However, 8 and 12 weeks after transplantation, the graft survival rate decreased. The grafts developed cell layers in folded sheets and many rosettes (a rosette consists of photoreceptors and cells of other retinal layers around a central lumen defined by an outer limiting membrane). Cografts of retina with RPE had areas of more distinct cell lamination than transplants of pure retina. Grafted RPE cells were organized in clusters of cells surrounded by extracellular matrix and often associated with blood vessels. If the extracellular matrix of RPE cell clusters was outside the rosettes close to inner retinal layers in the graft, transplant Müller cell endfeet developed an inner limiting membrane. Müller cell endfeet could also be observed in subretinal transplants attached to the denuded Bruch's membrane of the host. In 12-week grafts, when RPE cell clusters were inside rosettes, the surrounded photoreceptors survived better. No RPE effect could be seen if single RPE cells were dispersed among retinal donor cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Reversed ratio of color-specific cones in rabbit retinal cell transplants.

Recently, we have reported on the emergence of various retinal cell types in embryonic rabbit retina transplanted to adult rabbits. When comparing the relative numbers of the spectrally different cone types in the transplants to those in the host or age-matched control retinas, a surprising shift was observed. While in the normal rabbit retina the middle-wavelength-sensitive (M) cones are considerably more abundant than the short-wave-sensitive (S) cones, the S/M cone ratio was found to be the opposite in the graft. The number of rosettes containing only S-cones in high density was found to be considerably higher than that of M-cone rich rosettes. The number of S-cones also exceeded that of the M-cones in each rosette that contained both cell types. Our results were obtained from the systematic immunocytochemical analysis of 15 different transplants derived from transplantations of embryonic rabbit retinas into adult hosts of the same species. The emergence and proportion of the two cone types were followed between 14 and 63 days after transplantation (between 29 and 78 postconceptional days of the donor tissue). Sections from various parts of the transplants were reacted with the monoclonal antibodies COS-1 and OS-2, specific for the middle- and short-wavelength-sensitive cones, respectively. The explanation for the reverse cone ratio in these transplants is not known yet, however, the observed phenomenon may indicate differences between the specification of the two basic cone types.

Animals↗
PubMed1994

Development of cell markers in subretinal rabbit retinal transplants.

Retinas from embryonic rabbits at day E15 were transplanted to the subretinal space in adult rabbits. After survival times between 7 and 193 days, the rabbits were killed, and the transplants were processed for immunohistochemistry. The results show that subretinal transplants from embryonic rabbit retinas develop many, if not all, retinal neuronal types. The cells show approximately normal morphology and express a variety of cell-type-specific markers: photoreceptor cells express visual pigment proteins as identified by antibodies against rhodopsin (R2-15), color-specific cone pigments (COS-1, OS-2) and the cone specific antigen 50-1B11, rod bipolar cells express PKC, horizontal cells HPC-1 antigen and neurofilament 160 kDa, amacrine cells HPC-1 antigen, GABA and neurofilament 160 kDa, and glial cells express vimentin and glial fibrillary acidic protein. The high degree of rosette formation seen in many young grafts, diminishes with time; many transplant cells disappear, and the remaining cells present a less prominent formation of rosettes.

Animals↗
PubMed1994

Interphotoreceptor matrix components in retinal cell transplants.

To further investigate the functional potential of retinal transplants we have used immunocytochemistry to study the distribution of four different interphotoreceptor matrix (IPM)-specific components in rabbit retinal transplants. The different components were: interphotoreceptor retinoid-binding protein (IRBP), chondroitin-6-sulfate, F22 antigen and peanut agglutinin (PNA) binding structures. IRBP acts as a retinoid-transport protein between the neural retina and the retinal pigment epithelium. Chondroitin-6-sulfate is a glycosaminoglycan and a part of the insoluble IPM skeleton. The identity and role of the F22 antigen is not known. However, it is a 250 kDa protein localized to specific extracellular compartments such as teh IPM. PNA is a lectin with a high binding affinity for D-galactose-beta (1-3) N-acetyl-D-galactosamine disaccharide linkages and binds to IPM domains surrounding cones, but not rods. The transplants (15-day-old embryonic rabbit retina) were placed between the neural retina and retinal pigment epithelium in adult hosts. The transplants developed the typical rosette formations with photoreceptors toward the center. IRBP labeling was distinct in the IPM in the host retina. However, no IRBP labeling could be detected in the transplants. The chondroitin-6-sulfate and F22 antibodies strongly labeled the IPM in the host retina and corresponding structures in the center of rosettes. A cone-specific labeling with PNA could be seen in the host retina. In the transplants, however, PNA labeling appeared in association with many more photoreceptors than in the host retina. There is no previous study available on the IPM in retinal cell transplants.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗