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Biomedical subjects

R Klein

Publications and source records attributed to R Klein.

At least 505 records · Page 28Linked to original sources
PubMed1993

Sera from patients with tuberculosis recognize the M2a-epitope (E2-subunit of pyruvate dehydrogenase) specific for primary biliary cirrhosis.

Anti-M2 antibodies in primary biliary cirrhosis (PBC) have been shown to react with the alpha-ketoacid dehydrogenase complex of the inner mitochondrial membrane consisting of six epitopes (E2 subunit of the pyruvate dehydrogenase complex (PDC), 70 kD; protein X of the PDC, 56 kD; alpha-ketoglutarate dehydrogenase complex, 52 kD; branched-chain alpha-ketoacid dehydrogenase, 52 kD; E1 alpha subunit of PDC, 45 kD; and E1 beta-subunit of PDC, 36 kD). These epitopes are also present in the M2 fraction which is a chloroform extract from beef heart mitochondria. The E2 subunit of the PDC at 70 kD (M2a), especially, is a major target epitope which is recognized by about 85% of all PBC sera. However, analysing sera from 28 patients with active pulmonary tuberculosis it became evident that 12 (43%) also recognized the PDC-E2 subunit (M2a), as shown by Western blotting using the M2 fraction, the purified PDC, and the recombinant PDC-E2. In contrast, only two of 82 patients with other bacterial and viral infections including 25 patients with Escherichia coli infections reacted with the PBC-specific epitope at 70 kD. Naturally occurring mitochondrial antibodies (NOMA) were present in 54% of the patients with tuberculosis and in 50% of patients with other infectious disorders. They recognized either a determinant at 65 kD (epsilon) or at 60/55 kD (zeta/eta). None of the sera from 100 blood donors had anti-M2 but 14 had NOMA. Testing anti-M2 and NOMA-positive marker sera by Western blotting against membrane fractions derived from mycobacteria and E. coli it could be shown that--like mammalian mitochondria--they contain both the PBC-specific M2 antigen as well as the non-PBC-specific naturally occurring mitochondrial antigen system (NOMAg). The observation that PBC-specific antibodies were preferentially induced in patients suffering from a mycobacterial infection may provide some new clues to the still unknown etiology of PBC.

Adolescent↗
PubMed1993

Cloning and characterization of the RNA polymerase alpha-subunit operon of Chlamydia trachomatis.

We have cloned the chlamydial operon that encodes the initiation factor IF1, the ribosomal proteins L36, S13, and S11, and the alpha subunit of RNA polymerase. The genes for S11 and alpha are closely linked in Escherichia coli, Bacillus subtilis, and plant chloroplast genomes, and this arrangement is conserved in Chlamydia spp. The S11 ribosomal protein gene potentially encodes a protein of 125 amino acids with 41 to 42% identity over its entire length to its E. coli and B. subtilis homologs; the gene encoding the alpha subunit specifies a protein of 322 amino acids with 25 to 30% identity over its entire length to its E. coli and B. subtilis homologs. In a T7-based expression system in E. coli, the chlamydial alpha gene directed the synthesis of a 36-kDa protein. Mapping of the chlamydial mRNA transcript by RNase protection studies and by a combination of reverse transcription and the polymerase chain reaction demonstrates that IF1, L36, S13, S11, and alpha are transcribed as a polycistronic transcript.

Amino Acid Sequence↗
PubMed1993

The prevalence by staged severity of various types of diabetic neuropathy, retinopathy, and nephropathy in a population-based cohort: the Rochester Diabetic Neuropathy Study.

The magnitude of the health problem from diabetic neuropathies remains inadequately estimated due to the lack of prospective population-based studies employing standardized and validated assessments of the type and stage of neuropathy as compared with background frequency. All Rochester, Minnesota, residents with diabetes mellitus on January 1, 1986, were invited to participate in a cross-sectional and longitudinal study of diabetic neuropathies (and also of other microvascular and macrovascular complications). Of 64,573 inhabitants on January 1, 1986 in Rochester, 870 (1.3%) had clinically recognized diabetes mellitus (National Diabetes Data Group criteria), of whom 380 were enrolled in the Rochester Diabetic Neuropathy Study. Of these, 102 (26.8%) had insulin-dependent diabetes mellitus (IDDM), and 278 (73.2%) had non-insulin-dependent diabetes mellitus (NIDDM). Approximately 10% of diabetic patients had neurologic deficits attributable to nondiabetic causes. Sixty-six percent of IDDM patients had some form of neuropathy; the frequencies of individual types were as follows: polyneuropathy, 54%; carpal tunnel syndrome, asymptomatic, 22%, and symptomatic, 11%; visceral autonomic neuropathy, 7%, and other varieties, 3%. Among NIDDM patients, 59% had various neuropathies; the individual percentages were 45%, 29%, 6%, 5%, and 3%. Symptomatic degrees of polyneuropathy occurred in only 15% of IDDM and 13% of NIDDM patients. The more severe stage of polyneuropathy, to the point that patients were unable to walk on their heels and also had distal sensory and autonomic deficits (stage 2b) occurred even less frequently--6% of IDDM and 1% of NIDDM patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Radioimmunoassay of FSH-suppressing protein in the ewe: concentrations during the oestrous cycle and following ovariectomy.

A sensitive and specific heterologous radioimmunoassay for FSH-suppressing protein (FSP or follistatin) was applied to ovine plasma. Following a logit-log dose transformation, parallel dose-response lines were observed between purified bovine 35 kDa FSP used as standard and serial dilutions of ewe plasma. Activin-A, inhibin-A and a range of other proteins showed low (< 0.5%) cross-reactivity in the assay. Daily variations in the peripheral concentrations of FSP were measured across the ovine oestrous cycle. The peripheral concentrations of plasma FSP in adult ewes revealed a significant (P < 0.01) increase (33%) during the luteal phase above follicular phase levels, peaking 10 days after the LH surge. FSP concentrations were determined in arterial and venous plasma from the ovary, head, kidney and liver. A significant (P < 0.05) increase across the ovary was detected with no significant differences across the head, liver and kidney. To investigate the relationship between gonadal FSP and the pituitary, ewes underwent ovariectomy and hypophysectomy. FSP levels rose (100-110%, P < 0.01) during the period of surgery for both bilateral ovariectomy and sham ovariectomy, and then decreased significantly (37-44%) at 4-6 h after surgery. A further rise in plasma FSP (180-200% increase above pretreatment levels, P < 0.001) was observed 10-12 h after ovariectomy and sham ovariectomy. FSP levels then returned to preoperative levels during the following 26 h. Plasma FSP levels in long-term ovariectomized and hypophysectomized ewes were not significantly different from preoperative levels. To determine whether the pattern of plasma FSP seen during the ovariectomy study was due to the effect of the induction of anaesthesia, ewes were treated with sodium thiopentone and halothane or 0.9% (w/v) NaCl by procedures of similar duration to that used during surgery. Both treatments resulted in an elevation of FSP levels (33-62%) over pretreatment values only at the time of induction of anaesthesia. To examine further whether this rise in plasma FSP observed after anaesthesia was due to a stress response and therefore under the control of the pituitary-adrenal axis, ewes were treated with ACTH, dexamethasone or saline only. A further group of sheep were exposed to a barking dog for 10 min. No change in FSP levels compared with pretreatment levels or saline-treated controls were noted following any of these treatments.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenocorticotropic Hormone↗
PubMed1993

Diagnostic x-ray exposure and lens opacities: the Beaver Dam Eye Study.

The Beaver Dam Eye Study is a population-based study of common age-related eye diseases. During the standardized medical history, the 4926 subjects were asked whether they had ever had a chest x-ray, computerized axial tomography (CAT) scan of the head, other x-rays of the head, x-rays of the abdomen, or other diagnostic x-rays. The eye examination included photographs of the lenses of the eyes, which were subsequently graded according to protocol. Nuclear sclerosis and posterior subcapsular opacity were significantly associated with CAT scans. If these relationships are causal, it would highlight the importance of minimizing such exposure to the lens of the eye.

Adult↗
PubMed1993

Incidence of gross proteinuria in older-onset diabetes. A population-based perspective.

A few population-based studies describe the incidence of gross proteinuria in people with diabetes. We performed a population-based study in southern Wisconsin of diabetic individuals diagnosed at > or = 30 yr of age either taking insulin (n = 398) or not taking insulin (n = 441). The presence of gross proteinuria (> or = 0.3 g/L) was determined by means of a reagent strip. The incidence of proteinuria in the 4-yr interval was 17.3% (95% CI 13.6-21.0) in those taking insulin and 10.7% (95% CI 7.8-13.6) in those not taking insulin. The relative risk of developing proteinuria for those in the highest level of total pack-yr smoked compared with those who had never smoked was 2.0 (95% CI 1.2-3.3) for those taking insulin and 2.5 (95% CI 1.3-4.5) for those not taking insulin. After controlling for other risk variables, the incidence of gross proteinuria was also associated with higher GHb. These data suggest that smoking and glycemic control, both potentially modifiable factors, are significant risk factors for the development of gross proteinuria.

Adult↗
PubMed1993

Prevalence of microalbuminuria in older-onset diabetes.

OBJECTIVE: To examine the prevalence of microalbuminuria and the relationships of microalbuminuria to blood pressure and other risk factors. RESEARCH DESIGN AND METHODS: Individuals diagnosed with diabetes at > or = 30 yr of age either taking insulin (n = 435) or not taking insulin (n = 363), who were participants in the population-based Wisconsin Epidemiologic Study of Diabetic Retinopathy, were examined during 1984-1986. Random urine samples were collected and an agglutination inhibition test was used to determine the presence of microalbuminuria, which is defined as > or = 0.03 g/L but < 0.3 g/L. RESULTS: The frequency of microalbuminuria was 29.2% in those individuals taking insulin and 22.0% in those not taking insulin. Microalbuminuria was significantly associated with the male sex, older age, higher systolic blood pressure, higher GHb, use of insulin, higher recent alcohol consumption, and a history of cardiovascular disease. CONCLUSIONS: These findings suggest a relationship between controllable risk factors, blood pressure and GHb, and microalbuminuria in older-onset diabetic individuals.

Adult↗
PubMed1993

Blood pressure, hypertension and retinopathy in a population.

This study provides precise estimates of the prevalence of retinal lesions in nondiabetic persons with and without hypertension. The findings suggest that retinopathy (6% in normotensives and 11% in people with hypertension), and retinal arteriolar narrowing (11% in normotensives and 19% in people with hypertension) are common. Further longitudinal study is necessary to evaluate the public health significance of these findings.

Adult↗
PubMed1993

Antibiotic impregnated bone cement in total hip arthroplasty. An in vivo comparison of the elution properties of tobramycin and vancomycin.

A prospective in vivo quantification was performed to measure the elution of tobramycin and vancomycin antibiotics from two commonly used bone cements. Forty patients were divided into four groups: Group I, tobramycin-Simplex; Group II, tobramycin-Palacos-R; Group III, vancomycin-Simplex; and Group IV, vancomycin-Palacos-R. Antibiotic levels were measured from hemovac wound drainage, urine, and serum and compared with control groups who received either intravenous tobramycin or vancomycin. There were no significant differences in daily mean tobramycin levels in hemovac samples between Groups I and II. Tobramycin hemovac levels from Groups I and II were significantly higher than the tobramycin control group. Similarly, no differences were seen in daily mean vancomycin levels of the hemovac samples between Group III and IV; however, the intravenous vancomycin control group had significantly higher levels in the hemovac fluid than Groups III or IV. Tobramycin in the hemovac fluid from Groups I and II was highly bioactive against the control organism. Vancomycin in the hemovac fluid from Groups III and IV had variable bioactivity against the control organism. In 30% of the cases, no vancomycin was detected in the hemovac fluid, and in these cases, the hemovac fluid had no effect on the control organism. Tobramycin elutes to give adequate local tissue levels and releases antibiotic effects when used in an antibiotic bone cement combination. Vancomycin has variable elution properties and is not a predictable additive for the bone cements tested.

Bone Cements↗
PubMed1993

Characterization and clinical relevance of liver-pancreas antibodies in autoimmune hepatitis.

The isolation of a marker antigen from rat liver and pancreas tissue, which reacts with antibodies in a subtype of autoimmune hepatitis by complement fixation test, enzyme-linked immunosorbent assay and Western blot, is described. The liver-pancreas antigen could be detected in tissue from different human or animal organs, but liver and pancreas yielded the highest activity. A highly specific antigen fraction was obtained by gel filtration and ion exchange chromatography with a 100,000 g supernatant from rat liver tissue, and this preparation was shown to be devoid of nuclear, mitochondrial and microsomal antigens and cytokeratin 8 and 18, as demonstrated by appropriate marker antibodies. These data and absorption studies with cell organelles indicate that liver-pancreas antigen is a cytosolic protein. By Western blotting, two major epitopes at molecular weights 52 kD and 48 kD could be visualized. Sera from 175 patients previously shown to have high complement-fixing activity to a nonpurified liver-pancreas antigen fraction were further analyzed. All were positive by enzyme-linked immunosorbent assay with the purified liver-pancreas antigen fractions, and 111 were also positive by Western blot. Eighty-six sera reacted with the 52-kD determinant, 33 with the 48-kD determinant and 2 with both determinants. In 117 of the 175 patients, antibody to liver-pancreas antigen was associated with other autoantibodies known to characterize subgroups of autoimmune hepatitis. Thus 19 patients had antibodies to nuclei and 96 to actin but none to liver-kidney microsomes, hereby suggesting that antibody to liver-pancreas antigen may define another subgroup of autoimmune hepatitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Migraine headache and its association with open-angle glaucoma: the Beaver Dam Eye Study.

PURPOSE: To investigate the relationship of a history of migraine headache to open-angle glaucoma. METHODS: In an epidemiologic study of age-related eye disease, subjects were asked if they had migraine headaches. The diagnosis of glaucoma was based on visual field, intraocular pressure, cup/disc ratio, and history. RESULTS: Those younger than 65 years were significantly more likely to report a history of migraine (P = 0.001) as were women (P < 0.001). There was no difference in the frequency of open-angle glaucoma between those with and those without migraine headache (P = 0.87). Multivariate analyses did not alter the conclusion. CONCLUSION: In this population-based study there is no evidence of a relationship between open-angle glaucoma and migraine headache.

Adult↗
PubMed1993

Induction of noncatalytic TrkB neurotrophin receptors during axonal sprouting in the adult hippocampus.

Brain-derived neurotrophic factor (BDNF) and its signal transducing receptor, the TrkB tyrosine protein kinase, are expressed at high levels in the hippocampus of the adult brain, suggesting a role for BDNF mechanisms in neuronal plasticity. To test this hypothesis, we used defined lesions of perforant path and fimbria-fornix, two major hippocampal afferents, to remove synapses on dendrites of dentate gyrus granule cells and pyramidal cells of Ammon's horn and induce synaptic rearrangements. These combined lesions remove afferent connections from entorhinal cortex and septum and produce massive sprouting of axons of the commissural/associational pathways into the molecular layer of the hippocampal dentate gyrus. At days 1, 3, and 6, the lesions decreased BDNF mRNA expression ipsilaterally to approximately 50% of control, with complete recovery at 14 d. The lesions did not alter trkB mRNA levels in neuronal layers of the hippocampus; however, they resulted in a pronounced induction of trkB mRNA expression in hippocampal non-neuronal cells 6-14 d after lesioning. The induction corresponded in time and place to the synaptic reorganization in the lesioned hippocampus. The mRNA species newly induced by the lesions corresponded to those transcripts encoding the noncatalytic TrkB receptor isoform that lacks the cytoplasmic protein kinase domain. Expression of mRNAs coding for neurotrophin-3 and the TrkC tyrosine protein kinase were not altered by the lesions. The findings suggest that truncated noncatalytic TrkB molecules expressed on the surface of glial cells play an important role in plasticity of the adult brain, possibly regulating the concentration of bioactive neurotrophins or the responsiveness of neurotrophin receptors. Alternatively, they may play a role in presenting neurotrophin molecules to growing axons.

Animals↗
PubMed1993

Co-localization of the tumor-suppressor protein p53 and human papillomavirus E6 protein in human cervical carcinoma cell lines.

The loss of the tumor-suppressor activity of p53, either by mutation or by interaction with the human papillomavirus (HPV) E6 protein, is considered to be an important mechanism in the carcinogenesis of cervical cancer. We have studied the cytological distribution of these proteins in human cervical carcinoma cell lines using polyclonal anti-p53 and monoclonal anti-E6 antibodies. The antibody specificity was confirmed by immunoblot and immunocompetition analyses. The intracellular localization of p53 and E6 was detected using the techniques of conventional and three-dimensional confocal microscopy. In the HPV-18 or -16 integrated cell lines, HeLa, CaSki and SiHa, viral oncoprotein E6 and endogenous tumor-suppressor protein, p53, were observed by immunofluorescence in the cytoplasm; p53 also had a weak punctate staining in the nuclei of HeLa and CaSki cells. In the HPV-negative cervical carcinoma cell lines, C-33A and HT-3, which have mutated p53, p53 was localized predominantly to the nucleus, with C-33A cells having elevated levels of p53 compared with the other cell lines. High spatial resolution imaging, using confocal microscopy, was performed on the cells after double fluorescence staining for p53 (fluorescein) and E6 (rhodamine). The images showed that both p53 and E6 had similar cytoplasmic distributions, which implied that these two proteins may exist as a cytoplasmic complex. To substantiate this implication, fluorescence resonance energy transfer microscopy was performed, which provided direct evidence of a close association between p53 and E6 within individual HeLa cells. The results from this study support the theory that p53 protein binds HPV-16/18 E6 protein in the cell cytoplasm, thus preventing p53 from exerting its tumor-suppressor function in the nucleus. Hence, inactivation of wild-type p53 by p53-E6 complex formation in cervical cancer may be a critical step in malignant transformation.

Carcinoma↗
PubMed1993

Signal transduction events mediated by the BDNF receptor gp 145trkB in primary hippocampal pyramidal cell culture.

The trkB gene encodes a tyrosine kinase receptor, gp145trkB, for brain-derived neurotrophic factor (BDNF) and neurotrophin-4 (NT-4). To understand the role of gp145trkB in the nervous system, we have investigated its expression in embryonic rat hippocampal pyramidal cell cultures and examined the effects of BDNF on signal transduction in the primary neurons. The expression of trkB transcripts was established by PCR analysis and in situ hybridization. In addition to gp145trkB, the pyramidal neuronal cultures expressed transcripts specific for the NT-3 receptor gp145trkC, but not for the high-affinity NGF receptor gp140trk or for p75LNGFR, a low-affinity receptor for all known members of the NGF family of neurotrophins including the gp145trkB ligands, BDNF and NT-4. The presence of gp145trkB receptors in the primary neuronal cultures was confirmed by immunocytochemical analysis in which > 90% of the cells stained with affinity-purified polyclonal antibodies to gp145trkB. Immunoblots using this antibody revealed a single approximately 140 kDa protein in both adult hippocampus and pyramidal cultures. Addition of recombinant BDNF to these cultures induced the tyrosine phosphorylation of gp145trkB, as determined by antiphosphotyrosine staining of gp145trkB immunoprecipitates. Moreover, BDNF treatment activated the microtubule-associated protein (MAP) kinases, as determined by an increase in MAP2 phosphorylation in vitro. Both the 41 and 44 kDa forms of MAP kinase were activated by BDNF. BDNF also increased c-fos expression in over 90% of the cells. These results indicate that gp145trkB does not require p75LNGFR to form a functional receptor for BDNF in hippocampal pyramidal neurons.

3T3 Cells↗
PubMed1992

The single-copy gene psbS codes for a phylogenetically intriguing 22 kDa polypeptide of photosystem II.

Recombinant phages that encode the complete precursor polypeptide for the 22 kDa polypeptide associated with photosystem II have been serologically selected from two lambda gt11 expression libraries made from polyadenylated RNA of spinach seedlings. The cDNAs hybridize to a 1.3 kb RNA species. The precursor protein is comprised of 274 amino acid residues and carries an N-terminal transit peptide of probably 69 amino acid residues. The mature protein exhibits four predicted transmembrane segments and is shown to be an integral component of photosystem II originating in a single-copy gene. The unique characteristics of this protein are: (i) it is the result of a gene-internal duplication of an ancestor with two membrane spans, (ii) a striking resemblance to LHC I/II, CP24/CP29 apoproteins, and ELIPs, although it does not bind chlorophyll and is present in cyanobacteria, and, as these proteins, (iii) it integrates into the membrane with uncleaved routing signals that display remarkable resemblance to patterns found in bipartite transit peptides.

Amino Acid Sequence↗
PubMed1992

[The analysis of a severe side effect of a cartilage-protective agent by immunological studies].

After 18 intramuscular injections of Arumalon, a 62-year-old woman with degenerative hip-joint changes developed a severe illness with fever up to 39 degrees C, swellings of the finger, hand and knee joints, as well as a local skin rash and changes in the blood (WBC 1900/microliters, platelets 113,000/microliters), and increase in liver enzymes (GOT 83 U/l, GPT 93 U/l, lactate dehydrogenase 693 U/l). Arumalon, a glucosaminoglycan-peptide complex containing a watery extract of bovine cartilage and bone marrow, is used as a cartilage-protecting medication. The close temporal relationship between the injections and the symptoms suggested that the illness was drug-induced. This view was supported by a positive lymphocyte transformation test with Arumalon and its constituents, as well as by the demonstration of Arumalon-specific antibodies in the cultured lymphocyte fluid while the serum was negative for the antibodies. The illness took a protracted course. The patient became completely free of symptoms only after a year on a maintenance dose of prednisone, 15 mg daily. As a local inflammatory reaction was noted at the very start of the Arumalon injections, presensitization against the foreign proteins in Arumalon cannot be excluded. This is also supported by the fact that the specific lymphocyte proliferation was essentially unchanged even after nine months. This case illustrates the importance of careful assessment of increased and repeated manifestations of local reaction during Arumalon treatment, in particular in view of the risk of systemic side effects.

Acute Disease↗