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Biomedical subjects

R Klein

Publications and source records attributed to R Klein.

At least 91 records · Page 5Linked to original sources
PubMed2001

[Frequency of the common cold in healthy subjects during exposure to a lectin-rich and a lectin-poor mistletoe preparation in a randomized, double-blind, placebo-controlled study].

BACKGROUND/OBJECTIVE: Mistletoe preparations have immunomodulatory properties in vitro and in vivo. We wanted to investigate whether or not these properties have an effect on the frequency of the common cold in healthy subjects. PROBANDS AND METHODS: During a randomized, placebo-controlled, double-blind study 16 volunteers received the mistletoe lectin(ML)-poor preparation Iscador Pini(R) (IP), 16 the ML-rich preparation Iscador Quercus spezial(R) (IQ), and 16 placebo (physiological saline solution) twice a week subcutaneously for 12 weeks. Weekly during weeks 1-12 and finally at week 26, a careful history of common cold symptoms was taken. Because the frequency of the common cold was not the main outcome criterion in this study, the number of cases needed to treat was not adjusted to this criterion. RESULTS: The mean frequency of the common cold during the 12 weeks of injection was 1.5 in the placebo, 1.4 in the IP and 1.1 in the IQ group. During this period in 2.3 (placebo), 1.9 (IP) and 1.4 (IQ) weeks symptoms of common cold were present. The difference in favor to IQ lasted until the end of the observation period in week 26. It was, however, not significant. Leukocyte and granulocyte count as well as C-reactive protein were not different between the groups. CONCLUSIONS: The study showed a trend (p = 0.4, exact Kruskal- Wallis test) to reduced frequency and duration of the common cold in subjects who were exposed to IQ.

Adult↗
PubMed2001

Effect of contact stress on friction and wear of ultra-high molecular weight polyethylene in total hip replacement.

This paper studies the effect of contact stress on friction and wear of ultra-high molecular weight polyethylene (UHMWPE) acetabular cups by means of friction and wear joint simulator testing under serum lubrication. For a given applied load, increasing the contact stress by increasing the ball/socket radial clearance decreased both the coefficient of friction and the wear rate. Friction and wear were highly correlated. The dependence of friction on contact stress for the UHMWPE socket under serum lubrication was similar to that of semi-crystalline polymers under dry sliding. This finding indicates the occurrence of partial dry contact at asperity levels for the metal-polyethylene ball-in-socket joint under serum lubrication.

Arthroplasty, Replacement, Hip↗
PubMed2001

Peak expiratory flow rate: relationship to risk variables and mortality: the Wisconsin Epidemiologic Study of diabetic retinopathy.

OBJECTIVE: To examine correlates of peak expiratory flow rate in people with type 1 diabetes and to evaluate the relationship of peak expiratory flow rate to mortality. RESEARCH DESIGN AND METHODS: A cohort study that was originally designed to determine the prevalence, incidence, and severity of diabetic retinopathy also provided the opportunity to measure peak expiratory flow rate. This was first measured at a 10-year follow-up and was evaluated in regard to risk factors for microvascular complications of diabetes. Mortality during 6 years of follow-up after the measurement was also ascertained. RESULTS: In multivariable analysis, peak expiratory flow rate was associated with sex, age, height, BMI, history of cardiovascular disease, pulse rate, duration of diabetes, glycosylated hemoglobin, and end-stage renal disease. Peak expiratory flow rate was significantly associated with survival in categorical analyses. Even after considering age, sex, renal disease, history of cardiovascular disease, respiratory symptoms, duration of diabetes, cigarette smoking, and hypertension, peak expiratory flow rate was still significantly related to survival (hazard ratio 0.61 [95% CI 0.46-0.82]). CONCLUSIONS: These data indicate that peak expiratory flow rate is associated with risk factors for other complications of diabetes. In addition, peak expiratory flow rate is a significant predictor of survival over even a relatively short period of time (6 years) in patients with younger-onset diabetes.

Adolescent↗
PubMed2001

Diabetes and diabetic retinopathy in a Mexican-American population: Proyecto VER.

OBJECTIVES: The prevalence rate of diabetes is probably higher in Hispanics than in Caucasians, although there is controversy about differences in the risk of diabetic retinopathy. The purpose of the study is to determine the prevalence rates of diabetes and diabetic retinopathy in a population-based study of Hispanics aged > or = 40 years. RESEARCH DESIGN AND METHODS: Proyecto VER is a random sample of Hispanic populations aged > or = 40 years in Arizona. A total of 4,774 individuals (71.6% of the eligible sample) completed the examinations. Diabetes was defined as self-report of a physician diagnosis or HbA(1c) value of > or = 7.0%. Diabetic retinopathy was assessed on stereo fundus photographs of fields 1, 2, and 4. RESULTS: The prevalence rate of diabetes in the Hispanic community (individuals > or = 40 years of age) was 22%. The prevalence rate of diabetic retinopathy (DR) was 48%; 32% had moderate to severe nonproliferative and proliferative retinopathy. DR increased with increasing duration of diabetes and increasing level of HbA(1c). The prevalence rate of DR-like changes in the sample of individuals without diabetic retinopathy was 15% and was not associated with hypertension, systolic blood pressure, or diastolic blood pressure. CONCLUSIONS: The prevalence rate of diabetes in this population of Hispanics is high, almost twice that of Caucasians. The prevalence rate of DR is high but similar to reports in a Caucasian population. The prevalence rate of 9% moderate to severe retinopathy in the newly diagnosed group suggests that efforts to improve detection and treatment of diabetes in Hispanics may be warranted.

Adult↗
PubMed2001

Sunlight and the 5-year incidence of early age-related maculopathy: the beaver dam eye study.

OBJECTIVE: To investigate the relation of sunlight exposure and indicators of sun sensitivity with the 5-year incidence of early age-related maculopathy (ARM). DESIGN: Longitudinal, population-based study. Participants (aged 43-86 years at baseline) in the Beaver Dam Eye Study were reexamined from 1993 to 1995, 5 years after the baseline examination. Questionnaire data about sunlight exposure and sun sensitivity were obtained at baseline. Additional information about earlier life patterns of exposure was ascertained at follow-up. Stereoscopic color fundus photographs were graded to determine the presence of ARM at the 5-year follow-up in eyes free from signs of early ARM at the baseline examination. RESULTS: Leisure time spent outdoors while persons were teenagers (aged 13-19 years) and in their 30s (aged 30-39 years) was significantly associated with the risk of early ARM (odds ratio, 2.09; 95% confidence interval, 1.19-3.65). There was a slight, but nonsignificant, protective effect associated with use of hats and sunglasses while persons were teenagers and in their 30s (odds ratio, 0.72; 95% confidence interval, 0.50-1.03). People with red or blond hair were slightly more likely to develop early ARM than people with darker hair (odds ratio, 1.33; 95% confidence interval, 0.97-1.83). There were no associations between estimated ambient UV-B exposure or markers of sun sensitivity and the incidence of early ARM. CONCLUSION: Exposure to sunlight may be associated with the development of early ARM.

Adult↗
PubMed2001

Macular edema and retinal hard exudates in African Americans with type 1 diabetes: the New Jersey 725.

OBJECTIVE: To determine frequency and associated risk factors for macular edema and retinal hard exudates in hospitalized African Americans with type 1 diabetes. SUBJECTS AND METHODS: Included were 725 African Americans with type 1 diabetes who participated in the New Jersey 725. Clinical evaluations consisted of a structured clinical interview, ocular examination, stereoscopic fundus photographs, and blood pressure measurements. Presence of macular edema and hard exudates was determined via masked grading of fundus photographs. Biological evaluations included blood and urine assays. RESULTS: Of the 725 patients, 89 (12.3%) had macular edema and 149 (20.6%) had retinal hard exudates in at least 1 eye. The presence of macular edema and hard exudates was significantly associated with older age at examination, longer duration of diabetes, and severity of diabetic retinopathy. Presence of proteinuria, missing insulin injections at least once a week, and longer duration of diabetes were significantly and independently associated with macular edema. Presence of proteinuria, male sex, higher low-density lipoprotein cholesterol levels, and longer duration of diabetes were significantly and independently associated with severity of retinal hard exudates. CONCLUSION: Macular edema and hard exudates are common in African Americans with type 1 diabetes, particularly in patients with evidence of renal disease.

Adolescent↗
PubMed2001

Psychometric properties of the 25-item NEI-VFQ in a Hispanic population: Proyecto VER.

PURPOSE: To assess the psychometric properties of the NEI-VFQ-25 in a population-based study of older Hispanic persons living in the United States, explore other demographic factors that affect participant response, and observe the comparability of the Spanish and English versions of the instrument. METHODS: A sample of randomly selected block groups in Tucson and Nogales, Arizona, were selected for study. Participants were interviewed at home; a majority of the interviews were conducted in Spanish. The home interview included questions from the NEI-VFQ-25 and HHANES: Presenting acuity was done using ETDRS methodology, followed by a standardized eye examination by an ophthalmologist. The authors analyzed the internal consistency of the NEI-VFQ-25 responses using Cronbach's alpha coefficient and the construct validity by assessing the relationship between presenting acuity and scale scores, adjusting for age and gender. A second model was also explored to determine whether other demographic variables affected scale scores; differences in reporting between the Spanish and English versions was observed in this model, used in a subset of the population that minimized interviewer effect. RESULTS: Of the 4774 participants in the study, 99.7% had completed questionnaires, not completed by proxy. The highest nonresponse rate occurred in the Driving scale, with 25% of participants not driving for reasons other than problems with vision. Internal consistency was high, with Cronbach alpha ranging between 0.65 and 0.86 for scales with multiple items. Adjusting for age and gender, those with presenting acuity worse than 20/40 scored significantly lower than those with presenting acuity 20/40 or better, for all scales. The demographic variables with the most consistent association across the NEI-VFQ-25 scales were presenting acuity, income, and gender. No significant differences in reporting were found between the Spanish and English versions of the questionnaire in the subset of the population. CONCLUSIONS: In this study of Hispanic people age 40 years or older, the NEI-VFQ-25 was sensitive to presenting acuity and other demographic variables, such as age, gender, and income. The findings from this psychometric analysis provide evidence of the reliability and validity of some of the scales in the 25-item NEI-VFQ when used among people with a range of visual acuity level, providing other explanatory variables are also considered.

Activities of Daily Living↗
PubMed2001

Refractive errors and incident cataracts: the Beaver Dam Eye Study.

PURPOSE: To describe the relation between refractive errors and incident age-related cataracts in a predominantly white US population. METHODS: All persons aged 43 to 84 years of age in Beaver Dam, Wisconsin, were invited for a baseline examination from 1988 through 1990 and a follow-up examination 5 years later from 1993 through 1995. At both examinations, participants had refraction and photographic assessment of cataract, according to a standardized protocol. Myopia was defined as a spherical equivalent of -1.0 diopters (D) or less, hyperopia as +1.0 D or more. The relations between refractive errors at baseline and cataract at baseline (prevalent cataract), 5-year incident cataract, and incident cataract surgery were analyzed by using generalized estimating equations. RESULTS: When age and gender were controlled for, myopia was related to prevalent nuclear cataract (odds ratio [OR], 1.67; 95% confidence interval [CI], 1.23-2.27), but not to cortical and posterior subcapsular cataracts. Myopia was not related to 5-year incident nuclear, cortical, and posterior subcapsular cataracts, but was related to incident cataract surgery (OR 1.89; CI 1.18-3.04). Hyperopia was related to incident nuclear (OR 1.56; CI 1.25-1.95) and possibly cortical (OR 1.25; CI 0.96-1.63) cataracts, but not to posterior subcapsular cataract or cataract surgery. After further adjustment for diabetes, smoking, and education, the association between myopia and incident cataract surgery was attenuated (OR 1.60; CI 0.96-2.64), but the associations between hyperopia and incident nuclear and cortical cataracts were unchanged. CONCLUSIONS: These data support the cross-sectional association between myopia and nuclear cataract seen in other population-based studies, but provide no evidence of a relationship between myopia and 5-year incident cataract. Hyperopia may be related weakly to incident nuclear and cortical cataract.

Adult↗
PubMed2000

The structural protein E of the archaeal virus phiCh1: evidence for processing in Natrialba magadii during virus maturation.

phiCh1 is a lysogenic virus for the haloalkalophilic archaeon Natrialba magadii. The virus morphology resembles other members of Myoviridae infecting Halobacterium species. The gene of the major capsid protein E of virus phiCh1 was cloned and the DNA sequence was determined. Gene E was mapped to a 3.2-kbp ClaI fragment, localized to the 5'-end of the phiCh1 genome. The complete nucleotide sequence of this region was determined and the identity of gene E was confirmed by comparing the experimentally determined N-terminal amino acid sequence of the purified protein to the translated DNA sequence of its open reading frame. We present evidence that the gene E product is proteolytically cleaved between Lys(16) and Asn(17) to yield the 305 residue polypeptides found in the mature viral capsid. Processing of the protein itself during virus development was determined by 2D gel electrophoresis using protein E-specific antibodies. Sequence similarity studies revealed an 80% identity to capsid protein Hp32 of phiH, infecting Halobacterium salinarum. RT-PCR analysis as well as Western blot studies revealed gene E as a late gene. Transcripts and proteins could be detected shortly before onset of lysis of the lysogenic strain N. magadii L11.

Amino Acid Sequence↗
PubMed2000

Role of brain insulin receptor in control of body weight and reproduction.

Insulin receptors (IRs) and insulin signaling proteins are widely distributed throughout the central nervous system (CNS). To study the physiological role of insulin signaling in the brain, we created mice with a neuron-specific disruption of the IR gene (NIRKO mice). Inactivation of the IR had no impact on brain development or neuronal survival. However, female NIRKO mice showed increased food intake, and both male and female mice developed diet-sensitive obesity with increases in body fat and plasma leptin levels, mild insulin resistance, elevated plasma insulin levels, and hypertriglyceridemia. NIRKO mice also exhibited impaired spermatogenesis and ovarian follicle maturation because of hypothalamic dysregulation of luteinizing hormone. Thus, IR signaling in the CNS plays an important role in regulation of energy disposal, fuel metabolism, and reproduction.

Adipose Tissue↗
PubMed2000

The risk of cardiovascular disease mortality associated with microalbuminuria and gross proteinuria in persons with older-onset diabetes mellitus.

BACKGROUND: Despite the numerous studies on the relation of albuminuria with increased risk of all-cause mortality in type 2 diabetes mellitus, it remains uncertain whether microalbuminuria and/or gross proteinuria are independent risk factors for cardiovascular mortality. Moreover, the association of albuminuria with cardiovascular mortality in people with type 2 diabetes mellitus has not been well described in US populations. OBJECTIVE: To estimate the relative risks (RRs) for the associations of microalbuminuria and gross proteinuria with cardiovascular disease mortality among persons with older-onset diabetes mellitus. METHODS: We conducted a prospective cohort study of 840 people with older-onset diabetes mellitus who provided urine samples in the 1984-1986 examination of a population-based study of diabetic persons. The presence of microalbuminuria was determined by an agglutination inhibition assay and gross proteinuria by a reagent strip. The main outcome was time to mortality from cardiovascular disease, as determined from death certificates. RESULTS: Of the 840 older-onset diabetic persons, 54.8% had normoalbuminuria, while 24.8% had microalbuminuria and 20.5% had gross proteinuria. During the 12-year follow-up (6127 person-years), we identified 364 deaths from cardiovascular disease. Compared with persons with normoalbuminuria, those with microalbuminuria and gross proteinuria had significantly higher risks of cardiovascular mortality. The RR as controlled for age, sex, glycemic control, insulin use, alcohol intake, physical activity, cardiovascular disease history, antihypertensive use, and retinopathy severity, was 1.84 (95% confidence interval [CI], 1.42-2.40) for those with microalbuminuria and 2.61 (95% CI, 1.99-3.43) for those with gross proteinuria. Further adjustment for other factors did not change the relations we found. When the end point used was mortality from coronary heart disease, stroke, or all causes, the increased risks were significant for both microalbuminuria (adjusted RRs [95% CIs], 1.96 [1.42-2.72], 2.20 [1.29-3.75], and 1.68 [1.35-2.09], respectively) and gross proteinuria (adjusted RRs [95% CIs], 2.73 [1.95-3.81], 2.33 [1.28-4.24], and 2.47 [1.97-3.10], respectively). CONCLUSIONS: Results from our population-based study strongly suggest that both microalbuminuria and gross proteinuria were significantly associated with subsequent mortality from all causes and from cardiovascular, cerebrovascular, and coronary heart diseases. These associations were independent of known cardiovascular risk factors and diabetes-related variables.

Aged↗
PubMed2000

Shc-binding site in the TrkB receptor is not required for hippocampal long-term potentiation.

Recent evidence shows that neurotrophins are not only involved in neuronal survival and differentiation but also in modulating synaptic strength in the developing and adult nervous system. To understand how neurotrophins induce changes in synaptic strength, we have investigated signaling pathways downstream of the TrkB receptor, which binds brain-derived neurotrophic factor (BDNF) or NT-4/5. To test whether the Shc-site activated signaling pathway, which has been shown to be important for neuronal survival in vivo, also plays a role in processes like long-term potentiation (LTP), we have generated a mouse strain carrying a mutation in the Shc-binding site of the TrkB receptor. In hippocampal slices from these mice we investigated whether basal synaptic transmission, early-LTP (E-LTP) or late-LTP (L-LTP) were affected by this mutation. We found that homo- and heterozygous mutant mice show no difference in the induction-rate or magnitude of E-LTP and L-LTP induced by theta-burst or tetanus stimulation, suggesting that the Shc-binding site in the TrkB receptor and its downstream activated signaling cascade is not involved in hippocampal synaptic plasticity.

Animals↗
PubMed2000

Recreational firearm use and hearing loss.

OBJECTIVE: To assess the relation between recreational firearm use and high-frequency hearing loss in a population of older adults. DESIGN: Cross-sectional, population-based cohort study. SETTING: The midwestern community of Beaver Dam, Wis. PARTICIPANTS: A population-based sample of 3753 participants (83% of those eligible), aged 48 to 92 years, participated in the baseline phase of the Epidemiology of Hearing Loss Study. INTERVENTION: None. MAIN OUTCOME MEASURES: Lifetime and past year self-reported firearm use during target shooting and hunting were assessed by interview. Hearing thresholds were measured by pure-tone audiometry. RESULTS: After age and other factors were adjusted for, men (n = 1538) who had ever regularly engaged in target shooting (odds ratio, 1.57; 95% confidence interval, 1.12-2.19) or who had done so in the past year (odds ratio, 2.00; 95% confidence interval, 1.15-3.46) were more likely to have a marked high-frequency hearing loss than those who had not. Risk of having a marked high-frequency hearing loss increased 7% for every 5 years the men had hunted (odds ratio, 1.07; 95% confidence interval, 1.03-1.12). Thirty-eight percent of the target shooters and 95% of the hunters reported never wearing hearing protection while shooting in the past year. CONCLUSIONS: These results indicate that use of recreational firearms is associated with marked high-frequency hearing loss in men. There is a need for further education of users of recreational firearms regarding the risk of hearing impairment associated with firearm use and the availability and importance of appropriate hearing protection.

Aged↗
PubMed2000

Vitamin supplement use and incident cataracts in a population-based study.

OBJECTIVE: To determine the relationship between vitamin supplement use and the 5-year incidence of nuclear, cortical, and posterior subcapsular cataract in the Beaver Dam Eye Study cohort. DESIGN: The 5-year incidence of cataract, determined from slitlamp (nuclear cataract) and retroillumination (cortical and posterior subcapsular cataract) photographs, was assessed in a population-based cohort of persons participating in baseline (1988-1990) and follow-up (1993-1995) examinations. Detailed data regarding the type, dosage, and duration of supplement use were obtained by in-person interviews at follow-up. PARTICIPANTS: Residents of Beaver Dam, Wis, aged 43 to 86 years, were identified by private census. Of the 3684 participants in both baseline and follow-up examinations, 3089 were eligible for incident cataract analysis in the present study. RESULTS: Compared with nonusers, the 5-year risk for any cataract was 60% lower among persons who, at follow-up, reported the use of multivitamins or any supplement containing vitamin C or E for more than 10 years. Taking multivitamins for this duration lowered the risk for nuclear and cortical cataracts but not for posterior subcapsular cataracts (odds ratios [95% confidence intervals] = 0.6 [0.4-0.9], 0.4 [0.2-0.8], and 0.9 [0.5-1.9], respectively). Use of supplements for shorter periods was not associated with reduced risk for cataract. Measured differences in lifestyle between supplement users and nonusers did not influence these associations, nor did variations in diet as measured in a random subsample. CONCLUSIONS: These data add to a body of evidence suggesting lower risk for cataract among users of vitamin supplements and stronger associations with long-term use. However, the specific nutrients that are responsible cannot be ascertained at this time, and unmeasured lifestyle differences between supplement users and nonusers may explain these results. Arch Ophthalmol. 2000;118:1556-1563

Adult↗