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Biomedical subjects

F Mayer

Publications and source records attributed to F Mayer.

At least 127 records · Page 7Linked to original sources
PubMed1994

Reproducibility of isokinetic peak torque and angle at peak torque in the shoulder joint.

Adequate reliability studies of knee flexion and extension are currently available for isokinetic measurements, but not for the shoulder joint. For this reason, this study examines the variability (%) in the determination of peak torque (PT) and the angle at peak torque (AP) in the test-retest procedure. Differentiation is made between the various types of work (concentric, isometric, eccentric) and the degrees of freedom in the shoulder joint (flexion/extension, abduction/adduction, external rotation/internal rotation). The results show a variability of PT for concentric measurements of 15.0%-19.0% for all degrees of freedom; for flexion/extension and abduction/adduction in isometric and eccentric work, the variability is 17.5%-25.3%. External and internal rotation show generally greater deviation (29.0%-35.3%), except in concentric work. The angle at peak torque can only be reproduced to a limited degree (25.1%-41.1% variability). It is concluded that lower reproducibility can be attained for the shoulder joint compared to the knee joint, depending on the degree of freedom and exercise form tested. It appears meaningful to cite only ranges for the angle at peak torque.

Adult↗
PubMed1994

The cardiocirculatory reaction to isokinetic exercises in dependence on the form of exercise and age.

Although isokinetic training is gaining in importance in prevention and rehabilitation, even for older patients, there is hardly any information available on the extent of cardiocirculatory stress. This study was aimed, therefore, at examining the cardiocirculatory reaction to various isokinetic forms of exercise in dependence on age. Sixty-four subjects between 22 and 60 years of age were assigned to four age groups and the maximum torque measured in concentric and eccentric exercises with various angle accelerations. Moreover, all subjects underwent 1-min concentric and eccentric endurance stress and an isometric test. The cardiocirculatory reaction as reflected in heart rate and blood pressure patterns was determined, as well as the plasma catecholamines adrenaline and noradrenaline measured. The eccentric maximum torque was significantly above the concentric maximum torque; there was a significant inverse relationship to age only in the concentric mode of exercise (r = -0.48; p < 0.01). The cardiocirculatory reaction in endurance stress and isometry, like the behavior of heart rate, blood pressure, and plasma catecholamines, was greatest in concentric exercise, although the maximum strength values were lower, followed by eccentric exercise and isometry. Exercise values such as those attained in maximum ergometric forms of exercise were not reached. It is concluded that no special precautionary measures are required in isokinetic forms of exercise.

Adult↗
PubMed1994

Isokinetic force-velocity curves in patients following implantation of an individual total hip prosthesis.

There are only a few studies which could support conclusions concerning the strength of the muscles surrounding the hip joint and especially concerning the strength relationships following implantation of endoprostheses. The aim of this study was to examine the post-operative course of strength deficits in this musculature compared to clinical parameters. Fifty-eight patients between 30 and 67 years of age, in whom individual total hip prostheses were implanted, were clinically examined prior, 9 weeks and 6 months after surgery. Moreover, the maximum isometric strengths of abductors, flexors, and rotator muscles as well as maximum isokinetic strengths of the extensors and flexor musculature at 60 degrees/s and 120 degrees/s were measured. The flexor and extensor musculature already showed a clear increase in maximum strength after 9 weeks and 6 months. By contrast, the isometric strengths of the rotators increased only slightly, the abductor strength decreased after 9 weeks to below the preoperative baseline level and attained this level again only after 6 months. The clinical parameters Trendelenburg sign, limping, and walking capacity were clearly improved after 6 months, but no correlation to the abductor strength could be demonstrated. It is concluded that limp-free gait can be attained even without maximum strength increase in the abductors, which are important for fluid gait, at least for short distances. The importance of regular training of the rotator and abductor musculature in coxarthrosis is emphasized to delay limitation of movement and decreased strength in the sense of a capsule pattern.

Adult↗
PubMed1994

Phase II trial of intraperitoneal carboplatin in ovarian carcinoma patients with macroscopic residual disease at second-look laparotomy. A multicentre study of the French Fédération Nationale des Centres de Lutte Contre le Cancer.

BACKGROUND: Because of its antitumour activity and its pharmacological advantage when administered by the intraperitoneal route, carboplatin was studied in a phase II multicentric trial. The aim of the study was to determine the response rate and the toxicity of carboplatin administered intraperitoneally and to determine if pathological complete response could be attained in women with macroscopic residual ovarian cancer at second-look laparotomy after intravenous cisplatin chemotherapy. PATIENTS AND METHODS: Twenty-nine patients with macroscopical residual disease after intravenous cisplatin-based chemotherapy at second-look laparotomy, were treated at that time with 300 mg/m2 of carboplatin administered in the abdominal cavity every four weeks for six cycles. In instances of negative findings at physical and CT scan examination, laparotomy evaluation was performed and the catheter was removed. The dose of carboplatin was increased or decreased according to hematological toxicity. RESULTS: Efficacy is evaluable in 25 pts: 2 pts had pathological complete responses and 1 pt had microscopic disease (12% response rate of evaluable patients). Toxicity is evaluable for 135 cycles in 29 patients. No grade 4 hematological toxicity was observed, 2 pts had grade 3 leukopenia and 3 pts had grade 3 thrombocytopenia; grade 3 vomiting was observed in 11% of cycles. No peritoneal complication was observed; catheter dysfunction occurred after the first cycle in one patient who refused a surgical procedure to remove the catheter and to pursue treatment. CONCLUSION: Intraperitoneal carboplatin demonstrates efficacy in patients with macroscopical residual disease at second-look laparotomy after first-line cisplatin chemotherapy. The recommended dose for further studies is 300 mg/m2 administered every 4 weeks. A low response rate does not favour a randomised study.

Adult↗
PubMed1994

Purification and characterization of a 14-kilodalton protein that is bound to the surface of polyhydroxyalkanoic acid granules in Rhodococcus ruber.

The N-terminal amino acid sequence of the polyhydroxyalkanoic acid (PHA) granule-associated M(r)-15,500 protein of Rhodococcus ruber (the GA14 protein) was analyzed. The sequence revealed that the corresponding structural gene is represented by open reading frame 3, encoding a protein with a calculated M(r) of 14,175 which was recently localized downstream of the PHA synthase gene (U. Pieper and A. Steinbüchel, FEMS Microbiol. Lett. 96:73-80, 1992). A recombinant strain of Escherichia coli XL1-Blue carrying the hybrid plasmid (pSKXA10*) with open reading frame 3 overexpressed the GA14 protein. The GA14 protein was subsequently purified in a three-step procedure including chromatography on DEAE-Sephacel, phenyl-Sepharose CL-4B, and Superose 12. Determination of the molecular weight by gel filtration as well as electron microscopic studies indicates that a tetrameric structure of the recombinant, native GA14 protein is most likely. Immunoelectron microscopy demonstrated a localization of the GA14 protein at the periphery of PHA granules as well as close to the cell membrane in R. ruber. Investigations of PHA-leaky and PHA-negative mutants of R. ruber indicated that expression of the GA14 protein depended strongly on PHA synthesis.

Amino Acid Sequence↗
PubMed1994

Structural aspects and immunolocalization of the F420-reducing and non-F420-reducing hydrogenases from Methanobacterium thermoautotrophicum Marburg.

The F420-reducing hydrogenase and the non-F420-reducing hydrogenase (EC 1.12.99.1.) were isolated from a crude extract of Methanobacterium thermoautotrophicum Marburg. Electron microscopy of the negatively stained F420-reducing hydrogenase revealed that the enzyme is a complex with a diameter of 15.6 nm. It consists of two ring-like, stacked, parallel layers each composed of three major protein masses arranged in rotational symmetry. Each of these masses appeared to be subdivided into smaller protein masses. Electron microscopy of negatively stained samples taken from intermediate steps of the purification process revealed the presence of enzyme particles bound to inside-out membrane vesicles. Linker particles of 10 to 20 kDa which mediate the attachment of the hydrogenase to the cytoplasmic membrane were seen. Immunogold labelling confirmed that the F420-reducing hydrogenase is a membrane-bound enzyme. Electron microscopy of the negatively stained purified non-F420-reducing hydrogenase revealed that the enzyme is composed of three subunits exhibiting different diameters (5, 4, and 2 to 3 nm). According to immunogold labelling experiments, approximately 70% of the non-F420-reducing hydrogenase protein molecules were located at the cell periphery; the remaining 30% were cytoplasmic. No linker particles were observed for this enzyme.

Cell Compartmentation↗
PubMed1994

Identification of the Methanococcus voltae S-layer structural gene.

We have established that the gene which we had previously identified as encoding the Methanococcus voltae P-type ATPase is, in fact, the structural gene for the M. voltae S-layer protein. This conclusion is based on a comparison of the N-terminal sequence of S-layer protein prepared by two independent methods with that derived from the nucleotide sequence of the cloned gene. This conclusion was further supported by immunocytochemical localization of the antigen directed against the antibodies used in the cloning experiments.

Bacterial Proteins↗
PubMed1993

Cloning, sequencing and immunological characterization of the corrinoid-containing subunit of the N5-methyltetrahydromethanopterin: coenzyme-M methyltransferase from Methanobacterium thermoautotrophicum.

A 3.5-kb EcoRI fragment of the Methanobacterium thermoautotrophicum chromosome contains five open reading frames, mtrA to mtrE. The deduced N-terminal amino acid sequence of mtrA is identical with 26 N-terminal amino acids of a corrinoid-containing membrane protein from Methanobacterium. Computer-aided analyses of mtrA predicts 237 amino acids with a molecular mass of 25,603 Da for its gene product. A hydropathy plot of this amino acid sequence indicates one hydrophobic helical conformation near the N-terminus of the peptide which represents a tentative membrane-spanning region. The main part of the protein, however, shows hydrophilic domains, suggesting a location outside the cytoplasmic membrane. These domains are probably accessible by monospecific polyclonal antibodies raised previously against the corrinoid-containing membrane protein. The immunogold-labeling technique revealed that the corrinoid-dependent membrane protein was detectable at the cytoplasmic face of the membranes and of vesicle preparations. No significant identity of the deduced amino acid sequence was found with sequences of several corrinoid-containing enzymes. In contrast to the hydrophilic gene product of mtrA, four other gene products from the gene cluster encode extremely hydrophobic proteins. The N-terminal sequences of mtrC and mtrD are identical with two peptides of the N5-methyltetrahydromethanopterin:coenzyme-M methyltransferase complex from Methanobacterium, indicating that the mtr genes encode this membrane protein.

Amino Acid Sequence↗
PubMed1993

Principles of functional and structural organization in the bacterial cell: 'compartments' and their enzymes.

Most bacteria lack obvious compartmentation, i.e., structural partition of the cell into functional entities (organelles) formed by a closed biological membrane. Nevertheless, these organisms exhibit sophisticated regulation and interactions of their catabolic and anabolic pathways; they are able to exploit a great variety of carbon and energy sources, and they conserve and transform energy in an efficient manner. In a less stringent sense, 'compartments' are also present in bacteria if one accepts that bacterial 'compartments' are not necessarily surrounded by a membrane, but are rather defined as mere functional entities characterized by their structural components, their enzymes and other functional proteins such as binding proteins. This view would mean that the bacterial cell can be described as a highly organized structured system comprised of these functional entities. Regulated transport processes within 'compartments' and across boundaries involving low and high molecular mass compounds, solutes, and ions take place within the 'framework' constituted by this structured system. Special emphasis is given to the fact that many of the transport processes take place involving the functional entity 'energized membrane'. This 'framework', the structural basis for the functional potential of a bacterial cell, can be studied by electron microscopy. Advanced sample preparation techniques and imaging modes are available which keep the danger of artefact formation low; they can be applied at cellular and macromolecular levels. Recent developments in immunoelectron microscopy and affinity labelling techniques provide tools which allow to unequivocally locate enzymes and other antigens in the cell and to identify polypeptide chains in enzyme complexes. Application of these approaches in studies on cellular and macromolecular organization of bacteria and their enzyme systems confirmed some old views but also extended our knowledge. This is exemplified by a description of selected enzyme complexes located in the bacterial cytoplasm, in the cytoplasmic membrane or attached to it, in the periplasmic space, and attached to the cell wall or set free into the surrounding medium.

Aldehyde Oxidoreductases↗
PubMed1993

Reduction of disulfide bonds in an amyloidogenic Bence Jones protein leads to formation of "amyloid-like" fibrils in vitro.

Motivated by the finding that the amino acid sequence of the Bence Jones protein BJP-DIA was identical to that of the main protein component of the amyloid fibrils obtained from the same patient with AL-amyloidosis, (Klafki, H.-W., Kratzin, H.-D., Pick, A.-I., Eckart, K., Karas, M. & Hilschmann, N. (1992) Biochemistry 31, 3265-3272.), we attempted to create "amyloid-like" fibrils from the Bence Jones protein in vitro, without addition of proteolytic enzymes. Reduction of BJP-DIA, solubilized in PBS, pH 7.4, overnight at 37 degrees C resulted in the formation of a precipitate which had affinity for the dye Congo red. Electron microscopy of negatively stained samples of the reduced protein revealed aggregates of linear unbranched fibrils. SDS-polyacrylamide gel electrophoresis demonstrated that the precipitate consisted almost exclusively of intact light chain molecules. This result makes it possible to deduce a molecular model of these amyloid fibrils generated in vitro.

Amyloid↗
PubMed1993

[Chemotherapy of cancers of the uterine cervix with a combination of bleomycin, mitomycin, cisplatin and etoposide].

Sixty patients with advanced carcinoma of the cervix were treated with 3-week cycles of chemotherapy consisting of bleomycin (10 mg/m2, D1, 2, 3), mitomycin (10 mg/m2, D1), cisplatin (80 mg/m2, D3), etoposide (100 mg/m2, D1, 2, 3). Twenty-six patients had prior therapy. Toxicities noted were primarily nausea, vomiting, asthenia, fever and myelosuppression, especially in the pre-treated patients. One patient died of pulmonary toxicity. Of the 34 untreated patients, 25 objective responses (74%) were observed, with two complete responses (6%) and among the 26 pre-treated patients, ten objective responses (39%) with only one complete response. The mean duration of response was 3.8 months [2-14]. These data indicate that combination chemotherapy regimen is active against advanced and recurrent cervical cancer but caution is required for administration and continuation of treatment after four cycles. This method of chemotherapy has significant potential for primary treatment in patients with locally advanced disease.

Adenocarcinoma↗
PubMed1993

[Laparoscopic cholecystectomy in cholecysto-choledocholithiasis. "Therapeutic splitting" or conventional surgical procedure?].

In a prospective study the impact of preoperative, selective endoscopic cholangiography (ERC/P) and therapy was evaluated in 586 consecutive patients with symptomatic gallstone disease in respect of biliary pathology and laparoscopic cholecystectomy (n = 520). Exclusion criteria for the admission to the study were previous gastric surgery, necrotizing cholecystitis and gallbladder perforation. Because of presumed pathology on ultrasound, suggestive for common bile duct stones or papillary stenosis 59 patients (11.3%) had preoperative ERC/P. In all patients with calculi (n = 40) endoscopic stone removal was successfully performed with/without sphincterotomy (EPT), in three cases of clinically relevant stenosis EPT was indicated. Morbidity was 1.6% after ERC/EPT, in the endoscopic group operative morbidity and mortality was zero. In the non-endoscopic group (n = 461) sixteen complications occurred, although none could have been avoided by preoperative cholangiography. Two patients showed retained calculi (0.3%), missed by preoperative diagnostics. Both cases were successfully treated by ERC. Intraoperative cholangiograms were not done routinely (11%). In conclusion, we think, that selective, preoperative ERC/P, EPT and stone removal--if necessary--facilitate a very low morbidity and mortality in the laparoscopic treatment of complicated gallstone disease. By means of the "therapeutical splitting" the conversion to open bile duct surgery with all its higher morbidity and mortality can be eradicated. Also, only a few of the endoscopically operating hospitals already provide equipment for laparoscopic bile duct revision, not to talk about the gifted and experienced surgeons.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

[Evaluation of second look laparotomy in the management of epithelial ovarian tumors. 88 interventions performed at the Dijon CAC between 1979 and 1990].

OBJECTIVE: To evaluate the second look laparotomy in the treatment and management of epithelial ovarian carcinoma. DESIGN: A retrospective study (1979-1990). SETTING: Centre G.-F. Leclerc, Dijon. SUBJECTS: 88 patients underwent a 2e look laparotomy during the period. Most of them (69.3%) were stage III or IV cancers. RESULTS: The predictive value of a negative second look is of evidence: 5 years survival of 63% versus 4% if residual tumor is observed. Nevertheless the therapeutic value of a tumoral exenteration during the second look is not demonstrated: the 5 years survival is only of 7% for these patients. CONCLUSIONS: This study demonstrates the importance of an appropriate surgery during the first look in the management of ovarian tumors. The contribution of the second look is primarily a prognostical contribution.

Actuarial Analysis↗
PubMed1992

Periplasmic location of nitrous oxide reductase and its apoform in denitrifying Pseudomonas stutzeri.

Immunogold labelling techniques on ultrathin sections of low temperature embedded cells yielded evidence for the periplasmic location of the respiratory enzymes N2O reductase and nitrite reductase (cytochrome cd1) in Pseudomonas stutzeri strain ZoBell. Cell fractionation by spheroplast preparation and two-dimensional electrophoresis showed the absence of a membrane association of these enzymes. Immunocytochemical localization of N2O reductase in a mutant strain deficient in the chromophore of N2O reductase showed the gold label at the cell periphery, indicating that the copper chromophore processing takes place after export of this protein's apoform.

Bacterial Proteins↗
PubMed1992

A multivariant study of pituitary adenoma, obtainment of two logistic regression equations as an auxiliary support in the diagnosis of these tumors.

A multivariant analysis was carried out in 120 patients with pituitary adenoma (prolactinoma, HGH-secreting adenoma and nonfunctional adenoma) and an equation was obtained concerning the prolactinoma (whose independent variables were age, galactorrhea, impotence, stage, and pretreatment secretion of ACTH) and another one concerning the nonfunctional adenoma (with age evolution time, visual disturbance evolution and galactorrhea as independent variables). These equations are useful in the differential diagnosis. The internal validity of both equations was obtained by calculating the ROC curve and determining sensibility, specificity and predictive values at the "optimum point" of this curve.

Adenoma↗