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H Mayer

Publications and source records attributed to H Mayer.

At least 145 records · Page 8Linked to original sources
PubMed1993

Expression of human bone morphogenetic proteins-2 or -4 in murine mesenchymal progenitor C3H10T1/2 cells induces differentiation into distinct mesenchymal cell lineages.

The cDNAs encoding the human bone morphogenetic proteins BMP-2 and BMP-4 in an eukaryotic expression vector were permanently transferred into the murine mesenchymal progenitor cell line C3H10T1/2. Originally, these cells are known to differentiate into myotubes, adipocytes, and chondrocytes upon the addition of azacytidine. Permanent transfection of genes encoding human BMP-2 and BMP-4 induces differentiation into the osteogenic lineage. The osteogenic differentiation potential of C3H10T1/2 cells is substantiated by histochemical and genetic analyses of marker genes typical or specific for osteogenesis, including the parathyroid hormone receptor, alkaline phosphatase, osteopontin, osteonectin, and osteocalcin. In addition to osteoblast formation, development into adipocytes and chondrocytes is also observed, suggesting that BMP-2 and BMP-4 induce differentiation into three mesenchymal lineages.

Adipocytes↗
PubMed1993

Optimal spinal strength normalization factors among male railroad workers.

In spite of increasing interest in techniques and devices for quantifying trunk strength and lifting capacity, relatively little research has been done to determine optimal normalizing factors for strength. The isolation of the ideal factors is a critical prerequisite for comparison of patient data to expected physical capacities in the uninjured population. In the present study, 160 incumbent railroad workers from four heavy laboring jobs were tested for isokinetic trunk strength and lumbar/cervical isokinetic lifting capacity as part of a study to establish normative data (Union Pacific RR, Omaha, NE). Three variables relating height and weight were studied to determine optimal normalization: actual body weight (BW), ideal weight (IW) and adjusted weight (AW). "IW" is actually a height/weight variable based on a weight control chart specifying ideal weights for given heights and genders. "AW" represents the lesser of BW or IW. Subjects were tested for isokinetic trunk extension/flexion for lumbar (floor-to-knuckle) and cervical (knuckle-to-shoulder) lifts. Results demonstrated that the isolated trunk strength tests showed the best correlation coefficients with BW for flexion-extension work at 60 and 150 per sec. Moreover, the correlation coefficients between the lumbar isokinetic lifting peak force measures and BW were high (ranging 0.49-0.67, P < 0.001), with much lower correlations for AW or IW. By contrast, cervical correlations between Liftask peak force and the height/weight variables were all lower, and were also better for AW than for BW or IW (ranging 0.37-0.50). It appears that body weight is the best normalizing factor for isokinetic trunk flexor/extensor strength and lumbar (floor-to-knuckle) lifting.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

In situ saphenous vein grafts for femorodistal bypass: evaluation of endoscopically monitored valvulotomy on graft patency.

An overview of a total of 135 in situ femorocrural bypass operations is given. In the operations all grafts were anastomosed distally to the infrapopliteal arteries: to the proximal half of the crural vessels 52 times and to the distal half 83 times. The indication for surgery was critical limb ischaemia. In addition to routine intraoperative angiography, orthograde angioscopy of the graft was carried out to assess the completeness of valvulotomy in 96 patients (group A). In 39 patients (group B) for whom an endoscope was not available, completion angiography was conducted to ensure graft integrity. The two groups were comparable with respect to their composition. On the basis of the endoscopic findings, revisions were performed in 17 patients with incomplete valve ablation in group A, whereas in group B there were no interventions (P < 0.01, chi 2 test). Using life-table analysis, cumulative primary patency rates for groups A and B were 76% and 76% at 30 days, 62% and 44% at 1 year and 43% and 27% at 4 years, respectively. By comparison with the log rank test, a significant difference in patency among both groups could not be established (P = 0.18).

Aged↗
PubMed1993

Efficacy of clindamycin vaginal cream versus oral metronidazole in the treatment of bacterial vaginosis.

OBJECTIVE: To compare the efficacy and tolerance with 2% clindamycin vaginal cream versus oral metronidazole for the treatment of bacterial vaginosis. METHODS: This was a multicenter, randomized, double-blind study in which patients were randomly assigned to one of the following two regimens in a 1:1 ratio: clindamycin phosphate vaginal cream 2% (5 g intravaginally at bedtime for 7 days) plus two placebo capsules (twice a day for 7 days) or metronidazole 500 mg (two 250-mg capsules orally twice a day for 7 days) plus placebo vaginal cream (5 g intravaginally at bedtime for 7 days). The patients were seen for follow-up at 5-10 days and 25-39 days after completion of therapy. RESULTS: Seven investigators, four in Germany, two in Austria, and one in Switzerland, enrolled 407 patients. Four patients never received either protocol drug, leaving 403 evaluable for safety. Two hundred thirty-four patients were evaluable for efficacy. The analysis for all evaluable patients showed no significant difference between treatment groups. The cure or improvement rate at 1 month after therapy was 83% in the clindamycin group versus 78% in the metronidazole group. The incidence of drug-related adverse medical events was approximately 12% in both groups. CONCLUSIONS: Oral metronidazole and intravaginal clindamycin cream had a similar efficacy of 78 to 83%. Both drugs were tolerated, with vaginal candidiasis developing in 8.5 and 4.7% of the patients in the clindamycin and metronidazole groups, respectively.

Administration, Intravaginal↗
PubMed1992

Preliminary studies of 6 beta-hydroxydexamethasone and its importance in the DST.

The role of the metabolites of dexamethasone (DEX) in the dexamethasone suppression test (DST) has never been fully elucidated. We report here our preliminary studies of 6 beta-hydroxydexamethasone (6 OH-Dex), a known metabolite of DEX, on the hypothalamic-pituitary-adrenal (HPA) axis of the rat; its activity in the most commonly used radioimmunoassay for plasma DEX; and its plasma concentrations in a normal human subject during the standard 1.0 mg DST. Six OH-Dex administered subcutaneously to rats at a dose of 1 mg/kg was able to completely suppress corticosterone production for at least 3 hr. In the IgG Corp. radioimmunoassay for plasma DEX, 6 OH-Dex was moderately cross-reactive yielding a 50% cross-reactivity of 10%. Gas chromatographic coupled mass spectroscopic analysis of human plasma samples, obtained 12 to 20 hr after the oral ingestion of 1.0 mg DEX, demonstrated similar plasma concentrations for both the parent compound and the 6-hydroxyl metabolite. The relevance of these findings, particularly to pharmacokinetic studies of the DST, is discussed.

Animals↗
PubMed1992

Structural analysis of a novel sialic-acid-containing trisaccharide from Rhodobacter capsulatus 37b4 lipopolysaccharide.

Sialic-acid-containing lipopolysaccharides from Rhodobacter capsulatus 37b4 (S-form lipopolysaccharide), KB-1 (R-type lipopolysaccharide) and Sp 18 (deep R-type lipopolysaccharide) were investigated for the linkage and substitution of sialic acids. Methylation analysis and behaviour towards acid and enzymic hydrolysis indicated a non-reducing terminal location of sialic acids in the R-type lipopolysaccharide of strain Sp 18, whereas an internal, chain-linked location of sialic acids was found in the lipopolysaccharides of strains 37b4 and KB-1. For these latter strains, methylation analysis revealed a substitution of sialic acids by other sugars at position 7 for strain 37b4 and positions 4 and 7 for strain KB-1. In accordance with the chain-linked position of sialic acids, mild hydrolysis of R. capsulatus 37b4 lipopolysaccharide with acetic acid released a trisaccharide with sialic acid at the reducing terminus. Structural investigation of this trisaccharide by methylation analysis, 1H- and 13C-NMR spectroscopy revealed the presence of the disaccharide Gal1-6Glc at the non-reducing end, probably with an alpha-anomeric configuration of the galactose residue, i.e. melibiose, beta-glycosidically linked to position 7 of sialic acid. Therefore the structure Gal alpha 1-6Glc beta 1-7Neu5Ac is proposed for this core oligosaccharide from R. capsulatus 37b4 lipopolysaccharide.

Carbohydrate Sequence↗
PubMed1992

Carteolol incorporated into FAT-MLV liposomes: prolonged and decreased reduction of IOP.

Liposomes are used as carries providing a prolonged and improved drug action. They are capable of trapping beta-blockers such as Carteolol. In a randomized prospective double-blind clinical trial, Carteolol 2% suspended with frozen and thawed multivesicular large vesicles (FAT-MLV), FAT-MLV, and Carteolol 2% were applied to normal (slightly cataracterous) eyes and immediately after extracapsular cataract extraction or phakoemulsification with implantation of a posterior chamber lens in a standard procedure. Twenty-five patients were included in each group. Intraocular pressure (IOP) was measured for 3 days using applanation tonometry. In the normal eyes, a significant reduction of IOP was found for the patients receiving Carteolol and Carteolol MLV suspension. Moreover, an improved action and a prolongation of drug action was registered in the Carteolol/MLV group as compared to Carteolol treatment alone. After cataract operation, the control groups showed a significant increase in IOP. Carteolol produced a constant level of IOP but the Carteolol/MLV suspension showed a stronger decrease after ECCE and a still stronger decrease after phakoemulsification. Hence, Carteolol is suitable for the reduction of IOP but a Carteolol/MLV suspension is more effective, providing the possibility of a single application of a low-dose beta-blocker after cataract extraction with posterior chamber lens implantation.

Carteolol↗
PubMed1992

Structural changes in condylar cartilage following prolonged exposure to the human parathyroid hormone fragment (hPTH) 1-34 in vitro.

This investigation presents the structural changes in condylar cartilage incubated in the presence of human parathyroid hormone (1-34) in an organ culture system for 6 to 12 days. Control cultures maintained their cartilaginous characteristics whereas human parathyroid hormone (1-34)-treated cultures revealed the following modifications: (1) The chondroprogenitor cell zone at the apical region of the explant underwent a substantial enlargement. The cells changed from a mesenchyme-like morphology into polygonal, glycogen-rich cells that were tightly attached to each other by a fibrillar intercellular matrix, but even by 12 days the apical region was comprised of healthy cells. (2) The mineralizing zone in the hypertrophic cartilage revealed a change in its cellular population. Hypertrophic chondrocytes were replaced by cells with amoeboid extensions and large numbers of secretory granules or vesicles. Based upon the above findings it appears that the chondroprogenitor cells that are initially stimulated to proliferate, are being suppressed from subsequent differentiation into chondroblasts; and that hypertrophic chondrocytes apparently undergo a dedifferentiation process followed by development into an as yet unknown cell population.

Animals↗
PubMed1992

A semiautomated, 96-well plate assay for collagen synthesis.

We have established a rapid method for the measurement of collagen synthesis in large numbers of cell cultures. 3H-labeled collagen in microwell cultures was salt precipitated, harvested, and washed using a commercially available cell harvester and the filtered collagen was directly counted. The cell number could then be assessed either by methylene blue staining or by dissolving the cells in NaOH and estimating the protein content with bicinchoninic acid. In all of these procedures, the samples remain in microtiter plates, thus ensuring that minimal amounts of reagents are used and minimizing the amount of manipulation necessary. The intergroup variability is 3 to 9% and the recovery of 3H-labeled collagen is greater than 90%. Using this method, large numbers of samples can be assessed for collagen synthesis quickly, conveniently, and for minimal cost.

Animals↗
PubMed1992

Structural differences in the outer core region of lipopolysaccharides derived from members of the genus Salmonella.

Spontaneous and P22-resistant rough mutants, respectively, selected from Salmonella IV (18: z36, z38:-) and S. djakarta (48: z4, z24:-), appeared to lack the epitope recognized by the T6 monoclonal antibody which had been previously shown to correspond to the terminal alpha-1,2-linked N-acetyl-D-glucosamine residue of the Salmonella lipopolysaccharide (LPS) Ra core. LPSs and core oligosaccharides were therefore prepared from these two rough mutants and analysed by chemical and serological methods. Sugar analyses as well as methylation and 13C-NMR studies indicated that rough mutants derived from these two serotypes indeed possessed outer core structures differing from those of the well-characterized Salmonella Ra core. Serological data corroborated the chemical findings. Proposed structures of the outer core regions of these two R-types are presented and the significance of the findings is discussed.

Carbohydrate Sequence↗
PubMed1992

Immunochemical and structural analysis of the O polysaccharides of Salmonella zuerich [1,9,27,(46)].

Salmonella zuerich [1,9,27,(46)] has been shown to exhibit two levels of structural heterogeneity. The bacterium carries two distinct O-polysaccharide molecules with and without O:factor 1. Both sets of molecules (1+ and 1-) carry the two O:factors 27 and 46 on the same O chain, but they are expressed unevenly; in contrast to factor 27, O:factor 46 is always weakly expressed. Part of this weak expression was thought to be due to strong inhibition of factor 46 by factor 1. In this study, serological analysis gave more detailed information on the sizes of the different O:factor epitopes. Structural analysis of S. zuerich O polysaccharides showed that they are constructed of the expected chemical sequences characteristic of factors 1, 9, 27, and 46. No modification in the sugar sequence could account for the weak expression of O:factor 46. Factors 27 and 46 are present on oligosaccharides carrying either an alpha-Man (factor 27) or a beta-Man (factor 46) residue. In S. zuerich, the alpha-Man configuration is predominant, corroborating the expression of strong factor 27 and weak factor 46 on the bacteria. Questions raised by the existence of such heterogeneous O polysaccharides on the specificity of the O chain polymerase, as well as the place of S. zuerich in Salmonella evolution, are dicussed in this paper.

Carbohydrate Sequence↗
PubMed1992

New perspectives in the differentiation of bone-forming cells.

Bone formation comprises a complex but ordered sequence of events which involves the proliferation and differentiation of chondrogenic and osteoblastic precursor cells ultimately leading to the formation of a calcified extracellular matrix. This process can be observed in vivo but under these conditions is difficult to study at the molecular level. A number of in vitro models have been developed which recapitulate discrete elements of this process. Using these models, detailed information has been obtained regarding the differentiation of bone forming cells and the molecular biology of the mineralization process. It has been shown that, in vitro, osteoblastic precursor cells can form a mineralized matrix similar to that seen in vivo. This calcification process was shown to consist of three interdependent phases: proliferation, matrix maturation and mineralization. Each of these phases was characterized by the expression of particular genes. Osteoblast precursors have been cloned and consequently shown to be able to differentiate in vitro into a number of other mesenchymal cells, supporting the theory that osteoblasts are derived from multipotent mesenchymal cells. It is possible that markers derived from these models could be used in the future to extend our knowledge of bone formation in vivo.

Animals↗
PubMed1992

The relationship between body fat distribution and weight loss in obese adolescent girls.

Recent studies have demonstrated an association between the pattern of body fat distribution and the occurrence of cardiovascular risk factors. In this study, we evaluated changes in body fat distribution as defined by several anthropometric criteria during a six week weight reduction programme in 110 obese adolescent girls (mean age 15.2 +/- 0.4 years). The standardized regimen included a mixed diet of 1032 kcal/day and a daily exercise programme of 1-2 h duration. The mean weight loss was 8.6 +/- 2.8 kg, decreasing the body mass index (BMI) from 31.4 +/- 4.7 to 28.2 +/- 4.9 kg/m2 (P < 0.01). The reduction in body weight was accompanied by a significant decrease in the waist-to-hip ratio (WHR) from 0.86 +/- 0.06 to 0.81 +/- 0.05 (P < 0.01). The initial WHR was correlated with the degree of weight loss independent of the initial weight (r = 0.34, P < 0.001). Categorized according to the waist-to-hip ratio girls in the upper tertile (WHR > 0.88) lost significantly more weight than girls in the lower tertile (WHR < 0.80) (9.8 +/- 2.7 vs. 6.8 +/- 2.5 kg, P < 0.01). These findings suggest that girls with an abdominal type of obesity benefit more from a weight reduction programme than girls with a gluteal-femoral type of obesity.

Adipose Tissue↗
PubMed1992

[Use of internal fixator in injuries of the thoracic and lumbar spine].

Between 1984 and 1989 51 patients with spinal traumata received surgical treatment by means of Fixateur interne. The results of patients' postsurgical check-up were as follows: Cases with incomplete neurological dysfunctions (levels Frankel B-D)-especially lumbar-showed improvements of neurological deficiencies up to three levels Frankel after emergency decompression and stabilization. The majority of cases with complete paraplegia-especially thoracic-did not subside. This holds true even for the results of a second check-up after about three years. A correlation between the degree of stenosis of the spinal canal and the neurological dysfunctions could not be established. The results of segmental stabilization by means of internal fixator and of definitive spondylodesis by means of autogenous spongiosa were positive, as was the spine proof and the patients' postsurgical function.

Adolescent↗
PubMed1991

Identification of 3-deoxy-lyxo-2-heptulosaric acid in the core region of lipopolysaccharides from Rhizobiaceae.

A 3-deoxy-2-heptulosaric acid (DHA), very probably with the lyxo-configuration, was identified in the R-core region of lipopolysaccharides from nodulating strains of Rhizobium leguminosarum, Rhizobium meliloti and from all three biovars of the phytopathogenic Agrobacterium tumefaciens. Its structure could be deduced from the fragmentation pattern of the corresponding alditol acetates obtained after reduction of the 2-keto and the 1.7-carboxy groups by sodium borohydride or sodium borodeuteride. DHA in lipopolysaccharide was not destroyed by periodate and is therefore not in a terminal position. Two DHA-containing oligosaccharides, namely glucosyl (1----4)-3-deoxy-2-heptulosaric acid and rhamnosyl-rhamnosyl-(1----5)-3-deoxy-2-heptulosaric acid could be tentatively identified by mass spectrometric methods amongst the products of mild acidic hydrolysis of lipopolysaccharides of Rhizobium leguminosarum strain 24. The two types of non-nodulating mutants of Rhizobium leguminosarum included in this study did not contain 3-deoxy-2-heptulosaric acid.

Carbohydrate Sequence↗
PubMed1991

Stimulation of cell proliferation in skeletal tissues of the rat by defined parathyroid hormone fragments.

We have found, in previous studies in vitro using skeletal derived cell cultures, that mid-region fragments of human parathyroid hormone (hPTH) stimulate [3H]thymidine incorporation into DNA and increase the specific activity of the brain-type isoenzyme of creatine kinase (CK). These changes occurred without an increase in cyclic AMP formation which is linked to bone resorption. In this study, we found that the mid-region fragment hPTH-(28-48) stimulated CK activity in diaphysis, epiphysis and kidney in a time- and dose-dependent manner, parallel to the effects of the whole molecule bovine (b)PTH-(1-84) and the fully active fragment hPTH-(1-34). The increase caused by hPTH-(28-48) at a dose of 1.25 micrograms/rat was not less than the 2-fold increase caused by a roughly equimolar concentration bPTH-(1-84). A significant increase was reached at 1 h after intraperitoneal injection in all cases. All three sequences of PTH caused an increase in [3H]thymidine incorporation into DNA in diaphysis and epiphysis, but not in kidney, 24 h after injection. A fragment further towards the C-terminal, hPTH-(34-47), was inactive compared with an equimolar concentration of the fragment hPTH-(25-39), which stimulated both CK activity and DNA synthesis. These results in vivo are in line with previous findings in vitro; they provide further support for the suggestion that mid-region fragments of the PTH molecule could be used to induce bone formation without incurring the deleterious effect of bone resorption.

Animals↗
PubMed1991

Investigation of the solution structure of the human parathyroid hormone fragment (1-34) by 1H NMR spectroscopy, distance geometry, and molecular dynamics calculations.

The structure of human parathyroid hormone fragment (1-34) in a solvent mixture of water and trifluoroethanol has been determined by 1H nuclear magnetic resonance spectroscopy and a combination of distance geometry and molecular dynamic simulations. After complete assignment of the 1H signals, the nuclear Overhauser enhancement data imply the existence of two alpha-helices, comprising residues 3-9 and 17-28, joined by a nonstructured region. The absence of any long-range NOEs and the relative magnitudes of the sequential NOEs and the 3J(HNH alpha) values reflect an inherent flexibility within the entire fragment. The final structures refined by molecular dynamics further support the above results and allow discussion of structural-activity relationships.

Amino Acid Sequence↗