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Biomedical subjects

F Mayer

Publications and source records attributed to F Mayer.

At least 91 records · Page 5Linked to original sources
PubMed1997

Potato pulp: microbiological characterization, physical modification, and application of this agricultural waste product.

Potato pulp, one of the agricultural waste products obtained in high quantities during starch production, contains starch, cellulose, hemicelluloses, pectin, proteins, free amino acids and salts. It exhibits physical and physicochemical properties of a typical colloid. It is mainly used, in a dried and pelleted form, as cattle feed. Its autochthonic microbial flora (bacteria, fungi) was identified and studied with a view towards the degradative potential of the microorganisms and ways of conserving the pulp for subsequent technical applications; 33 isolates (28 bacteria, 4 fungi, 1 yeast), belonging to 15 genera were characterized. Biological conservation was possible at very low oxygen pressure, brought about by the autochthonic anaerobic microorganisms causing acidification. Chemical conservation was achieved with sorbic acid. By treatment with hot water vapour under pressure (autoclaving), followed by a pressure release procedure, intact cells in the pulp (both potato cells and microorganisms, not spores) were destroyed, and their contents and wall fragments were set free. This process resulted in low drying costs and was a prerequisite for the production of a powder that can be used as glue or as animal feed.

Adhesives↗
PubMed1997

Evolution of repeated sequence arrays in the D-loop region of bat mitochondrial DNA.

Analysis of mitochondrial DNA control region sequences from 41 species of bats representing 11 families revealed that repeated sequence arrays near the tRNA-Pro gene are present in all vespertilionine bats. Across 18 species tandem repeats varied in size from 78 to 85 bp and contained two to nine repeats. Heteroplasmy ranged from 15% to 63%. Fewer repeats among heteroplasmic than homoplasmic individuals in a species with up to nine repeats indicates selection may act against long arrays. A lower limit of two repeats and more repeats among heteroplasmic than homoplasmic individuals in two species with few repeats suggests length mutations are biased. Significant regressions of heteroplasmy, theta and pi, on repeat number further suggest that repeat duplication rate increases with repeat number. Comparison of vespertilionine bat consensus repeats to mammal control region sequences revealed that tandem repeats of similar size, sequence and number also occur in shrews, cats and bighorn sheep. The presence of two conserved protein-binding sequences in all repeat units indicates that convergent evolution has occurred by duplication of functional units. We speculate that D-loop region tandem repeats may provide signal redundancy and a primitive repair mechanism in the event of somatic mutations to these binding sites.

Animals↗
PubMed1997

Microbulbifer hydrolyticus gen. nov., sp. nov., and Marinobacterium georgiense gen. nov., sp. nov., two marine bacteria from a lignin-rich pulp mill waste enrichment community.

Two numerically important bacteria in marine pulp mill effluent enrichment cultures were isolated. These organisms were gram-negative, rod-shaped, strictly aerobic bacteria. Isolate IRE-31T (T = type strain) produced hydrolytic enzymes for the breakdown of cellulose, xylan, chitin, gelatin, and Tween 80. It also utilized a variety of monosaccharides, disaccharides, amino acids, and volatile fatty acids for growth. Isolate KW-40T did not utilize natural polymers, but it could grow on a variety of monosaccharides, disaccharides, alcohols, and amino acids. It also utilized methanol and aromatic compounds. The surfaces of both organisms were covered by blebs and vesicles. 16S rRNA analyses placed both organisms in the gamma-3 subclass of the phylum Proteobacteria. They were related to Oceanospirillum linum, Marinomonas vaga, Pseudomonas putida, and Halomonas elongata, although a close association with any of these bacteria was not found. The guanine-plus-cytosine contents of strain IRE-31T and KW-40T were 57.6 and 54.9 mol%, respectively. On the basis of 16S rRNA sequence and phenotypic characterizations, these isolates were different enough so that they could be considered members of new genera. Thus, the following two new genera and species are proposed: Microbulbifer hydrolyticus, with type strain IRE-31 (= ATCC 700072), and Marinobacterium georgiense, with type strain KW-40 (= ATCC 700074).

Base Composition↗
PubMed1997

Sagittula stellata gen. nov., sp. nov., a lignin-transforming bacterium from a coastal environment.

A numerically important member of marine enrichment cultures prepared with lignin-rich, pulp mill effluent was isolated. This bacterium was gram negative and rod shaped, did not form spores, and was strictly aerobic. The surfaces of its cells were covered by blebs or vesicles and polysaccharide fibrils. Each cell also had a holdfast structure at one pole. The cells formed rosettes and aggregates. During growth in the presence of lignocellulose or cellulose particles, cells attached to the surfaces of the particles. The bacterium utilized a variety of monosaccharides, disaccharides, amino acids, and volatile fatty acids for growth. It hydrolyzed cellulose, and synthetic lignin preparations were partially solubilized and mineralized. As determined by 16S rRNA analysis, the isolate was a member of the alpha subclass of the phylum Proteobacteria and was related to the genus Roseobacter. A signature secondary structure of the 16S rRNA is proposed. The guanine-plus-cytosine content of the genomic DNA was 65.0 mol%. On the basis of the results of 16S rRNA sequence and phenotypic characterizations, the isolate was sufficiently different to consider it a member of a new genus. Thus, a novel genus and species, Sagittula stellata, are proposed; the type strain is E-37 (= ATCC 700073).

Bacterial Adhesion↗
PubMed1997

Isolation and characterization of the homoacetogenic thermophilic bacterium Moorella glycerini sp. nov.

A thermophilic, anaerobic, spore-forming bacterium (strain JW/AS-Y6T) was isolated from a mixed sediment-water sample from a hot spring (Calcite Spring area) at Yellowstone National Park. The vegetative cells of this organism were straight rods, 0.4 to 0.6 by 3.0 to 6.5 microns. Cells occurred singly and exhibited a slight tumbling motility. They formed round refractile endospores in terminal swollen sporangia. Cells stained gram positive. The temperature range for growth at pH 6.8 was 43 to 65 degrees C, with optimum growth at 58 degrees C. The range for growth at 60 degrees C (pH60C; with the pH meter calibrated at 60 degrees C) was 5.9 to 7.8, with an optimum pH60C of 6.3 to 6.5. The substrates utilized included glycerol, glucose, fructose, mannose, galactose, xylose, lactate, glycerate, pyruvate, and yeast extract. In the presence of CO2, acetate was the only organic product from glycerol and carbohydrate fermentation. No H2 was produced during growth. The strain was not able to grow chemolithotrophically at the expense of H2-CO2; however, suspensions of cells in the exponential growth phase consumed H2. The bacterium reduced fumarate to succinate and thiosulfate to elemental sulfur. Growth was inhibited by ampicillin, chloramphenicol, erythromycin, rifampin, and tetracycline, but not by streptomycin. The G+C content of the DNA was 54.5 mol% (as determined by high-performance liquid chromatography). The 16S ribosomal DNA sequence analysis placed the isolate in the Gram type-positive Bacillus-Clostridium subphylum. On the basis of physiological properties and phylogenetic analysis we propose that the isolated strain constitutes a new species, Moorella glycerini; the type strain is JW/AS-Y6 (= DSM 11254 = ATCC 700316).

Base Composition↗
PubMed1997

Late recurrence of retinal detachment.

We reviewed 1,136 cases of retinal detachment in 1,073 patients. Late recurrence was defined as the reappearance of subretinal fluid after at least 6 months of clear, total reattachment. Fifty-one patients (4.75%) had a late recurrence. New or reopened peripheral breaks were either definitely observed or presumed to be present in 40 eyes (78.5%), and none were definite peripheral holes or retinal dialyses. Three macular holes reopened after having initially been managed by vitrectomy. One additional macular hole occurred as a new break. Late severe proliferative vitreoretinopathy occurred in the last 7 cases. Only vitrectomy for initial detachment and lens extraction after reattachment correlated with late recurrence. Vitrectomy was still a significant risk factor when macular holes were excluded.

Aged↗
PubMed1997

Inflammatory reactions induced by pretransplant conditioning--an alternative target for modulation of acute GvHD and complications following allogeneic bone marrow transplantation?

Intensity of pretransplant conditioning has been closely correlated with regimen related toxicity in patients receiving allogeneic bone marrow transplantation (BMT). In this review, we summarize evidence for a direct link between inflammatory reactions induced by irradiation and cytotoxic treatment and occurrence of acute graft-versus-host disease (GvHD) as well as endothelial complications: In our studies, de novo release of TNFalpha during conditioning was associated with an increased risk of severe GvHD and mortality following BMT, whereas increased spontaneous production of IL-10, an endogenous TNF-antagonist, prior to conditioning protected from these complications. Immunogenetic differences in cytokine regulation and costimulation by endotoxin proved to be important cofactors determining the extent of inflammatory cytokine release in individual patients. Pathophysiological relevance of these findings seems to be confirmed by experimental as well as first clinical trials using TNF-antibodies and related antagonists during pretransplant conditioning. Preclinical experiments suggest additional, cytokine independent inflammatory reactions induced by irradiation such as expression of ICAM-1 and endothelial cell apoptosis. Although the exact impact of these findings on pathophysiology of BMT related complications needs further clarification by future studies, conditioning related inflammation as a first crucial step in induction of GvHD and complications has to be considered when designing new protocols for preparation of patients for allogeneic BMT.

Animals↗
PubMed1997

[The optical power of the corneal epithelium. In vivo evaluation].

PURPOSE: The refracting power of the corneal epithelium is relatively unknown. We measured the keratometric refracting power of the cornea on 15 eyes of patients undergoing photorefractive keratectomy with and without epithelium. MATERIALS: The readings were performed with a videokeratoscope TMS-1. Three readings were averaged to obtain the mean and standard deviations. RESULTS: By removing the epithelium, there was an increase in corneal refracting power. The mean change was +1.19 D (standard deviation +/- 0.36 D) at 1 mm of the center of the cornea. On all patients the optical power of the cornea increased after epithelium removal. CONCLUSION: The curvature of the Bowman membrane is steeper than the cornea with epithelium. A change in the thickness of the epithelium is related to a modification of the optical power of the cornea. The optical role of the epithelium is to compensate surface irregularities of the Bowman membrane and could explained in part the hyperopia in the first months after excimer laser.

Cornea↗
PubMed1997

Prevalence, geographic distribution, and genealogical investigation of Machado-Joseph disease in the Azores (Portugal).

Machado-Joseph disease (MJD) is an autosomal, dominantly inherited neurodegenerative disorder of adult onset. The prevalence of MJD reaches its highest values in the islands of the Azores. A research program was undertaken to study the origin and spread of the mutant gene in the Azorean populations. Here, we present the first results of such a study. The Azorean MJD patients are grouped in 34 families and are distributed on 4 of the 9 Azore islands. Values of prevalence, carrier rate, and number of individuals at risk are reported. The genealogies of the patients were reconstructed to identify the founders. An analysis of the geographic distribution of the birthplaces of the patients compared with the birthplaces of the founders revealed the existence of areas that are clusters for both, thus defining crucial sites for the origin of the disease. Preliminary results on the number of links between the affected families show that 64.7% of them have at least one link with another MJD family. So far, a single source for the introduction of the mutant gene in the Azores has not been identified.

Adult↗
PubMed1997

[Clinical value of the estimation of growth kinetics of primary ovarian cancer recurrences by CA125 doubling time].

The aim of this retrospective work was to study the clinical importance of growth rate determination for ovarian cancer primary recurrence in term of CA125 doubling time (dt). Fifty-one patients with epithelial ovarian carcinoma stage III or IV who developed a recurrence were included. Eighteen spontaneous dt values were calculated in non-treated patients during follow-up and 33 apparent dt values were estimated in patients undergoing treatment during CA125 increase before the clinical and/or radiological diagnosis of recurrence. No early treatment of the recurrence has permitted a drop in CA125 level. We applied exponential regression models to CA125 individual kinetics in order to calculate dt values. Individual dt values vary from 5 to 375 days. Spontaneous and apparent dt medianes (respectively 64 and 39 days) are not significantly different. Among all early clinical, histological, biological and therapeutic parameters, the initial CA125 half-life calculated during the third courses of the first-line chemotherapy is the unique predictive parameter of dt (relative risk (RR) = 78; p < 0.01). The prognostic impact was more important in spontaneous dt values than in apparent ones. Being spontaneous or apparent dt was the major predictive parameter of the delay between the initial CA125 increase and clinical and/or radiological signs of recurrence (RR = 0.3; p < 0.0001). Its prognostic impact is superior to the T1/2 one (RR = 2.9; p = 0.0010). For equivalent treatments, dt (RR = 0.4; p < 0.0001) and T1/2 (RR = 4.0; p < 0.0001) are the only predictive parameters of the survival after CA125 increase. This work shows that dt was an essential predictive parameter of ovarian epithelial tumor recurrences.

Aged↗
PubMed1997

[Treatment of postoperative bile fistulas after laparoscopic cholecystectomy by ERCP, EPT and bile duct drainage].

BACKGROUND: Bile leakage as a complication following cholecystectomy can be found more frequently after laparoscopic cholecystectomy (LC) than after open cholecystectomy. The present study planned to find out the importance of ERCP, sphincterotomy and temporary drainage of the bile duct system in the treatment of bile leakage. PATIENTS AND METHODS: From July 1992 to October 1996 15 consecutive patients presenting with bile leakage following LC underwent endoscopic therapy by CBD-drainage with sphincterotomy (n = 11), CBD-drainage without sphincterotomy (n = 1) and sphincterotomy alone (n = 3). RESULTS: Closure of the bile leakage could be achieved in all cases, biliary secretion stopped after 2.1 days (1-7 days). One dislocation of the drainage into the CBD was found and could be treated endoscopically. Endoscopy-related mortality was 0%. CONCLUSIONS: Endoscopic therapy offers a safe, effective and minimal invasive method in the treatment of bile leakage following LC.

Adult↗
PubMed1997

[Confocal microscopy study of 2 cases of Thygeson's epithelial keratitis].

Two cases of bilateral Thygeson's keratitis were examined by in vivo confocal microscopy. In the corneas, fine deposits of highly reflected material appeared immediately below the basal lamina. This is the first time that such morphological features are described in patients with Thygeson's keratitis.

Adolescent↗
PubMed1997

[Potential for improvement of combined endoscopic-surgical treatment of bleeding gastroduodenal ulcer].

A total of 119 patients (January 1995-December 1996; 53 women, 66 men) with a medium age of 63.1 years were admitted to hospital with bleeding gastroduodenal ulcer. Emergency gastroduodenoscopy was performed immediately in all cases, sclerotherapy in 94 cases (78.9%). Control endoscopy was done routinely after 12-24 h; the recurrent bleeding rate amounted to 14.3%, mortality was 5%, and surgical intervention was necessary in 8.4% with a mortality of 40% (!).

Adolescent↗
PubMed1996

Subunit structure and organization of the genes of the A1A0 ATPase from the Archaeon Methanosarcina mazei Gö1.

The proton-translocating A1A0 ATP synthase/hydrolase of Methanosarcina mazei Gö1 was purified and shown to consist of six subunits of molecular masses of 65, 49, 40, 36, 25, and 7 kDa. Electron microscopy revealed that this enzyme is organized in two domains, the hydrophilic A1 and the hydrophobic A0 domain, which are connected by a stalk. Genes coding for seven hydrophilic subunits were cloned and sequenced. From these data it is evident that the 65-, 49-, 40- and 25-kDa subunits are encoded by ahaA, ahaB, ahaC, and ahaD, respectively; they are part of the A1 domain or the stalk. In addition there are three more genes, ahaE, ahaF, and ahaG, encoding hydrophilic subunits, which were apparently lost during the purification of the protein. The A0 domain consists of at least the 7-kDa proteolipid and the 36-kDa subunit for which the genes have not yet been found. In summary, it is proposed that the A1A0 ATPase of Methanosarcina mazei Gö1 contains at least nine subunits, of which seven are located in A1 and/or the stalk and two in A0.

Amino Acid Sequence↗
PubMed1996

Prerequisites and limitations to isokinetic measurements in humans. Investigations on a servomotor-controlled dynamometer.

Physical and technical limitations have to be considered when measuring small torques over a wide range of angles during joint movements in humans using isokinetic methods, i.e. at constant angular velocities. In the concentric mode, during the initial phase, the subject must actively accelerate the lever of the isokinetic dynamometer to a present velocity. To guarantee an adequate duration of the isokinetic phase at high present velocities, greater torques are necessary to produce appropriate accelerations, otherwise the isokinetic phase will be increasingly shortened until the preset velocity can no longer be attained. The servomotor-controlled dynamometer used (LIDO-Active 2.1) continuously records torque during the whole movement, irrespective of differences between the actual and the preset velocity, but the user is not informed about which torques have been recorded outside the isokinetic phase and at which actual velocity. Thus, in the evaluation of torques in the nonisokinetic range, errors occur due to assigning torque measurements to incorrect velocities and due to the non-negligible accelerations involved. In exploratory tests on the dynamometer using physical methods to produce constant torques, an attempt has been made to ascertain the range over which isokinetic conditions were satisfied, hence providing a reliable basis for isokinetic studies in sports medicine and sports sciences.

Biomechanical Phenomena↗
PubMed1996

Formation of intracytoplasmic lipid inclusions by Rhodococcus opacus strain PD630.

An oleaginous hydrocarbon-degrading Rhodococcus opacus strain (PD630) was isolated from a soil sample. The cells were able to grow on a variety of substrates and to produce large amounts of three different types of intracellular inclusions during growth on alkanes, phenylalkanes, or non-hydrocarbon substrates. Electron microscopy revealed large numbers of electron-transparent inclusions with a sphere-like structure. In addition, electron-dense inclusions representing polyphosphate and electron-transparent inclusions with an elongated disc-shaped morphology occurred in small amounts. The electron-transparent inclusions of alkane- or gluconate-grown cells were composed of neutral lipids (98%, w/w), phospholipids (1.2%, w/w), and protein (0.8%, w/w). The major component of the cellular inclusions was triacylglycerols; minor amounts of diacylglycerols and probably also some free fatty acids were also present. Free fatty acids and/or fatty acids in acylglycerols in cells of R. opacus amounted up to 76 or 87% of the cellular dry weight in gluconate- or olive-oil-grown cells, respectively. The fatty acid composition of the inclusions depended on the substrate used for cultivation. In cells cultivated on n-alkanes, the composition of the fatty acids was related to the substrate, and intermediates of the beta-oxidation pathway, such as hexadecanoic or pentadecanoic acid, were among the acylglycerols. Hexadecanoic acid was also the major fatty acid (up 36% of total fatty acids) occurring in the lipid inclusions of gluconate-grown cells. This indicated that strain PD630 utilized beta-oxidation and de novo fatty acid biosynthesis for the synthesis of storage lipids. Inclusions isolated from phenyldecane-grown cells contained mainly the non-modified substrate and phenylalkanoic acids derived from the hydrocarbon oxidation, such as phenyldecanoic acid, phenyloctanoic acid, and phenylhexanoic acid, and approximately 5% (w/w) of diacylglycerols. The lipid inclusions seemed to have definite structures, probably with membranes at their surfaces, which allow them to maintain their shape, and with some associated proteins, probably involved in the inclusion formation.

Fatty Acids↗
PubMed1996

Effect of combined parasympathetic and sympathetic blockade on left ventricular relaxation at rest and during exercise in trained and untrained men.

We investigated the influence of autonomic blockade (AB) on the left ventricular (LV) diastolic function at rest (R) and during bicycle exercise (EX) in eight endurance-trained (TR) and ten untrained subjects (UT). Two-dimensional and M-mode echocardiography at the parasternal long axis were performed at rest and during an exercise protocol, which consisted of two stages of 50 and 100 W. Using the digitized data from the M-mode echocardiogram, the normalized maximal increase in LV dimension during the rapid filling phase (nmD) was calculated according to Hörtnagl. Additionally the ECG was recorded at R and during Ex 60 min after this first test. 0.02 mg.kg body mass-1 propanolol and 0.04 mg.kg body mass-1 atropine were injected intravenously over a 5-min period and the test procedure was repeated as described above. Before AB nmD increased significantly from resting values to 100 W in both groups, whereas nmD tended to be lower in UT compared to TR. During AB nmD of UT was rather unchanged at R and during EX compared to pre-blockade conditions. In contrast nmD of TR was slightly reduced and this difference was significant at 100 W. No major difference in nmD between the TR and UT group could be observed during AB. Before and during AB HR of TR were significantly lower at rest, 50 and 100 W compared to UT. We conclude that the enhanced diastolic relaxation observed in endurance athletes seems to be due to a training-induced adaptation of the autonomic nervous system.

Adaptation, Physiological↗