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Biomedical subjects

J M Neuhaus

Publications and source records attributed to J M Neuhaus.

72 records · Page 4Linked to original sources
PubMed1989

The association of knee injury and obesity with unilateral and bilateral osteoarthritis of the knee.

The strength of the associations of knee injury and obesity with osteoarthritis of the knee was studied for 3,885 adults aged 45-74 years who received knee x-rays in the First National Health and Nutrition Examination Survey, 1971-1975. Bilateral osteoarthritis was more prevalent (5%) than unilateral osteoarthritis (2%). Bilateral osteoarthritis was twice as prevalent in women as in men; however, there was no sex difference in the prevalence of unilateral osteoarthritis. Odds ratios calculated by means of polychotomous logistic regression indicated that obesity, knee injury, and age were significantly associated with both unilateral and bilateral knee osteoarthritis. Obesity was a stronger predictor of bilateral osteoarthritis than was knee injury (odds ratio (OR) = 6.6 for obesity, 3.5 for right knee injury, and 3.0 for left knee injury; 95% confidence interval (CI) 4.71-9.18, 1.80-6.83, and 1.51-6.11, respectively). Knee injury was a stronger predictor of unilateral osteoarthritis than was obesity (OR = 3.4 and 2.4 for obesity in the right and left knee, respectively (95% CI 1.55-7.29 and 0.96-5.75) and OR = 16.3 and 10.9 for injury in the right and left knee, respectively (95% CI 6.50-40.89 and 3.72-31.93]. These findings suggest that different pathogenetic processes may exist for unilateral and bilateral knee osteoarthritis.

Age Factors↗
PubMed1988

Evidence for N- and C-terminal processing of a plant defense-related enzyme: Primary structure of tobacco prepro-beta-1,3-glucanase.

Tobacco glucan endo-1,3-beta-glucosidase (beta-1,3-glucanase; 1,3-beta-D-glucan glucanohydrolase; EC 3.2.1.39) exhibits complex hormonal and developmental regulation and is induced when plants are infected with pathogens. We determined the primary structure of this enzyme from the nucleotide sequence of five partial cDNA clones and the amino acid sequence of five peptides covering a total of 70 residues. beta-1,3-Glucanase is produced as a 359-residue preproenzyme with an N-terminal hydrophobic signal peptide of 21 residues and a C-terminal extension of 22 residues containing a putative N-glycosylation site. The results of pulse-chase experiments with tunicamycin provide evidence that the first step in processing is loss of the signal peptide and addition of an oligosaccharide side chain. The glycosylated intermediate is further processed with the loss of the oligosaccharide side chain and C-terminal extension to give the mature enzyme. Heterogeneity in the sequences of cDNA clones and of mature protein and in Southern blot analysis of restriction endonuclease fragments indicates that tobacco beta-1,3-glucanase is encoded by a small gene family. Two or three members of this family appear to have their evolutionary origin in each of the progenitors of tobacco, Nicotiana sylvestris and Nicotiana tomentosiformis.

Journal Article↗
PubMed1988

Living arrangements and eating behaviors of older adults in the United States.

Associations between living arrangements and several eating behaviors were examined for 4,402 adults aged 55 and older using three-day food intake data from the 1977-78 Nationwide Food Consumption Survey (NFCS). Compared to those living with a spouse, persons living alone ate more meals alone and consumed a higher proportion of total calories away from home; a higher proportion of those living alone skipped meals, including breakfast. There was a sex differential in the effect of living alone for some, but not all, of the eating behaviors. Both the probability of eating away from home and of skipping breakfast declined with age, as did the percentage of calories consumed from snacks. These results indicate a need to focus further research not only on the effects these eating behaviors have on the nutritional status of elderly persons, but also on middle-aged cohorts as they age and on food programs targeted at elderly persons living alone.

Aged↗
PubMed1988

Sex differences in osteoarthritis of the knee. The role of obesity.

This study investigated the role of obesity (body mass index, total body weight, triceps skinfold, subscapular skinfold) compared with other anthropometric variables (body fat distribution, muscularity, elbow breadth, bitrochanteric breadth) in order to explain previously noted sex differences in osteoarthritis of the knee. Anthropometric measures, self-reported symptoms, and knee x-ray data were analyzed for 3,905 adults aged 45-74 years with valid x-ray data from the First National Health and Nutrition Examination Survey, 1971-1975. Prevalence of knee osteoarthritis was 4.9% in women and 2.6% in men. The relative risk for women compared with men increased from 1.57 at 45-54 years to 2.14 at 65-74 years. Adjusting for body mass index and subscapular and triceps skinfolds reduced the sex difference, whereas adjusting for total body weight, body fat distribution, muscularity, and skeletal size increased the sex difference. Body mass index was the variable that best reduced the sex difference when the other variables were included in the analysis; it did not, however, eliminate the sex difference. No sex differences were found in the strength of the association between anthropometric variables and osteoarthritis, nor was there evidence to suggest that obesity is a consequence of knee osteoarthritis rather than a risk factor.

Adult↗
PubMed1988

The role of metabolic factors and blood pressure in the association of obesity with osteoarthritis of the knee.

The role of systemic/metabolic factors in the association of obesity with knee osteoarthritis (OA) was analyzed using radiographic data, metabolic measures, and blood pressure for 3885 American adults aged 45-74 from the U.S. National Health and Nutrition Examination Survey, 1971-1975 (NHANES I). Obesity was associated with both bilateral and unilateral OA, but more strongly with bilateral OA. Controlling for age, sex, serum cholesterol, serum uric acid, diabetes, body fat distribution, and blood pressure did not significantly reduce the association between obesity and knee OA. Findings from these data are not supportive of a metabolic link between obesity and knee OA.

Adipose Tissue↗
PubMed1987

Lactose permease of Escherichia coli: properties of mutants defective in substrate translocation.

Mutants of lactose permease of Escherichia coli with amino acid changes (Gly-24----Glu; Gly-24----Arg; Pro-28---Ser; Gly-24, Pro-28----Glu-Ser and Gly-24, Pro-28----Arg-Ser) within a putative membrane-spanning alpha-helix (Phe-Gly-Leu-Phe-Phe-Phe-Phe-Tyr-Phe-Phe-Ile-Met-Gly- Ala-Tyr-Phe-Pro-Phe-Phe-Pro-Ile) are incorporated into the cytoplasmic membrane. The mutant proteins retain the ability to bind galactosides, and the affinity for several substrates is actually increased. However, the rate of active transport is decreased to 0.01% of the wild-type rate in the mutants carrying Arg-24 or Arg-24, Ser-28. Kinetic analysis demonstrates that the two mutants require 10 min to cause occupied binding sites for galactoside and H+ to change their exposure from the periplasm to the cytoplasm as compared to 50 ms in the wild type. The effect is less pronounced when these sites are unoccupied.

Amino Acid Sequence↗
PubMed1985

Properties of a mutant lactose carrier of Escherichia coli with a Cys148----Ser148 substitution.

The cysteine residue at position 148 in the lactose carrier protein of Escherichia coli has been replaced by serine using oligonucleotide-directed, site-specific mutagenesis of the lac Y gene. The mutant carrier is incorporated into the cytoplasmic membrane to the same extent as the wild-type carrier, confers a lactose-positive phenotype on cells, and actively transports lactose and other galactosides. However, the maximum rate of transport for several substrates is reduced by a factor of 6-10 while the apparent affinity is reduced by a factor of 2-4. Carrier activity in the mutant is much less sensitive to sulfhydryl reagents (HgCl2, p-(chloromercuri)benzenesulfonate and N-ethylmaleimide) than in the wild type, and beta-D-galactosyl 1-thio-beta-D-galactoside does not protect the mutant carrier against slow inactivation by N-ethylmaleimide. It is concluded that the Cys148 residue is not essential for carrier-catalyzed galactoside: proton symport and that its alkylation presumbly prohibits access of the substrate to the binding site by steric hindrance. A serine residue at position 148 in the amino acid sequence appears to alter the protein structure in such a way that one or more sulfhydryl groups elsewhere in the protein become accessible to alkylating agents thereby inhibiting transport. Recently, Trumble et al. [(1984) Biochem. Biophys. Res. Commun. 119, 860-867] arrived at similar conclusions by investigating a mutant carrier with a Cys148----Gly148 replacement.

Amino Acid Sequence↗
PubMed1985

The actin treadmill.

Actin filaments can assemble at the barbed end and disassemble simultaneously at the pointed end. Prerequisites for this treadmilling reaction are the structural polarity of actin filaments and tight coupling of the actin assembly reaction and the adenosine triphosphate hydrolysis occurring during actin polymerization. In this article, investigations on the actin treadmill are reviewed.

Actins↗
PubMed1984

The crystallization of outer membrane proteins from Escherichia coli. Studies on lamB and ompA gene products.

The outer membrane protein LambB from Escherichia coli has been crystallized from detergent-containing solutions. Several different crystal habits can be obtained under the same ionic and precipitant conditions by altering the detergent head group composition of the protein-detergent mixed micelle or by adding polar organic compounds. Two crystal forms have been partially characterized as P1 and C2221, the former diffracting to beyond 4 A resolution and the latter to 6 A. The detergents used were beta-octyl glucoside, octyl tetraoxyethylene, and octyl polyoxyethylene (polydisperse) either alone or as mixtures. In some experiments, the addition of small nonionic amphiphiles having n-butyl alkyl tails significantly influenced crystallization. The experiments suggest that the detergent region of the mixed micelle plays a critical role in crystal formation. Using the methods developed here for LamB and also for matrix porin (Garavito, R. M., Jenkins, J. A., Jansonius, J. N., Karlsson, R., and Rosenbusch, J. P. (1983) J. Mol. Biol. 164, 313-327), an additional protein from the outer membrane, OmpA, has been obtained as a microcrystalline preparation.

Bacterial Outer Membrane Proteins↗
PubMed1983

Chemical modification of the lactose carrier of Escherichia coli by plumbagin, phenylarsinoxide or diethylpyrocarbonate affects the binding of galactoside.

The effects of chemical modification of the lactose carrier of Escherichia coli on galactoside binding (in overproducing strains) and on transport was examined. Both the modifying reagents diethylpyrocarbonate and rose bengal and the thiol reagents phenylarsinoxide and plumbagin can completely inhibit the binding of the substrate p-nitrophenyl alpha-D-galactopyranoside to the carrier. If care is taken to inhibit galactoside binding only partially, the loss of transport is found to parallel the loss of binding sites. The modified carrier molecules are completely inactive, while the remaining active carrier molecules evince normal transport and binding parameters. The binding of galactoside protects the carrier partially against these forms of chemical modification. In view of these observations, the results of previous chemical modification studies [Padan, E., Patel, L. and Kaback, H.R. (1979) Proc. Natl Acad. Sci. USA, 76, 6221-6225; Konings, W.N. and Robillard, G.T. (1982) Proc. Natl Acad. Sci. USA, 79, 5480-5484] must be re-interpreted. Our results stress the utility of studying substrate binding, the first step in the transport cycle.

Arsenicals↗
PubMed1983

The periplasmic maltose-binding protein modifies the channel-forming characteristics of maltoporin.

Maltoporin, a protein spanning Escherichia coli outer membranes, modifies electrical conductance of membranes due to its channel-forming properties. This observation was made by conductance measurements across planar bilayers which were derived from unextracted, isolated outer membrane vesicles using a porin-deficient E. coli strain. Alternatively, proteoliposomes reconstituted with detergent-solubilized homogeneous maltoporin and phospholipids were used. With either membrane preparation, channel conductance was observed, although no discrete conductance levels were detected. The presence of lipopolysaccharide, a bacterial glycolipid, was not required, nor did it affect channel activity. In the presence of the water-soluble periplasmic maltose-binding protein, conductance fluctuations occurred in discrete steps, demonstrating opening and closing events of channels. Multiple step sizes (1/3, 2/3 and 1 ns in 1 M KCl) in single channel traces suggest cooperative opening and closing of up to three channels. The action of maltose-binding protein is highly asymmetrical, and its affinity to maltoporin is very high (KD = 1.5 X 10(-7) M). Association of maltose-binding protein to maltoporin shifts, for a given polarity, the equilibrium between open and closed states in favour of closed states. This result matches earlier in vivo studies, and supports the physiological significance of the observations made.

ATP-Binding Cassette Transporters↗
PubMed1983

Treadmilling of actin.

Actin filaments can assemble at the barbed end and disassemble simultaneously at the pointed end. A higher monomer concentration is required to balance the association of actin monomers and the dissociation of filament subunits at the pointed end than at the barbed end. This treadmilling reaction or disparity of the apparent affinity of the two ends for monomers is caused by a continuous hydrolysis of adenosine triphosphate occurring during the association of a monomer with a filament end. In this article, in vitro investigations on treadmilling are reviewed and emerging physiological implications are discussed.

Actins↗
PubMed1982

Structural investigations of outer membrane proteins from Escherichia coli.

The receptor of phage lambda of Escherichia coli W3110, and matrix porin from E. coli BE have been crystallized. Porin occurs in two crystal forms whose packing arrangements are different, allowing the conclusion that crystal growth occurs from monodisperse protein-detergent complexes. The tetragonal form yields resolution to 2.9 A. The hexagonal form allows conclusive support for the hypothesis that a large fraction of the polypeptide is present in beta-pleated sheet structure with the strands nearly parallel to the normal of the membrane plane.

Bacterial Proteins↗