Search PubMed⌕ Search

Biomedical subjects

M Friedrich

Publications and source records attributed to M Friedrich.

At least 145 records · Page 8Linked to original sources
PubMed1997

Evolution and phylogeny of the Diptera: a molecular phylogenetic analysis using 28S rDNA sequences.

Portions of the large ribosomal subunit RNA gene (28S rDNA) encompassing the D1 and the D7 region were obtained from 16 dipteran species and families to reconstruct early phylogenetic events in the order Diptera. For outgroup comparison, the corresponding sequences were used from representative taxa of the Siphonaptera, Mecoptera, and Lepidoptera. A subset of 488 unambiguously alignable sites was analyzed with respect to important sequence evolution parameters. We found (1) sequence variability is significantly higher in double-stranded sites than in single-stranded sites, (2) transitions are close to saturation in most pairwise sequence comparisons, (3) significant substitution rate heterogeneity exists across sites, and (4) significant substitution rate heterogeneity exists among lineages. Tree reconstruction was carried out with the neighbor joining, maximum parsimony, and maximum likelihood methods. Four major subgroups are consistently and robustly supported: the Brachycera, the Culicomorpha, the Tipulomorpha sensu stricto, and the hitherto controversial Bibionomorpha sensu lato, which includes the families Sciaridae, Mycetophilidae, Cecidomyiidae, Bibionidae, Scatopsidae, and Anisopodidae. The phylogenetic relationships within or among these subclades and the positions of the families Psychodidae and Trichoceridae were not robustly resolved. These results support the view that the mouthparts of extant dipteran larvae evolved from a derived ground state characterized by subdivided and obliquely moving mandibles. Furthermore, sequence divergence and the paleontological record consistently indicate that a period of rapid cladogenesis gave rise to the major dipteran subgroups.

Animals↗
PubMed1997

Enhanced expression of T-cell activation and natural killer cell antigens indicates systemic anti-tumor response in early primary cutaneous T-cell lymphoma.

Indolent, primary cutaneous T-cell lymphomas (CTCL) are characterized by hyper-proliferation of malignant T-helper cells in the skin with a favorable prognosis in the early stages. Cytotoxic T cells (CTLs) are believed to be of major importance for tumor surveillance, but there is not yet sufficient evidence for a systemic anti-tumor response in mycosis fungoides (MF). On the contrary, there are hints of systemic immunodepression. We wondered whether signs of a systemic anti-tumor response were demonstrable in peripheral blood of patients with MF and CD30+ pleomorphic T cell lymphoma. Using multiparameter flow cytometry, we investigated blood samples from 39 CTCL patients at different stages and compared them with those from patients with psoriasis, atopic dermatitis, and healthy volunteers. In CTCL patients, an elevated number of lymphocytes expressing natural killer cell markers were found, as well as considerable T-cell activation, indicated by increased percentages of T cells expressing HLA-DR, IL-2 receptor alpha-chain, and transferrin receptor. The CD8+ T cells, which were the most strongly activated T-cell subset, were of polyclonal origin, as shown by their usage of different T-cell receptor families. The enhanced expression of activation antigens was associated with an increased proportion of CD8+ T cells with high expression of the adhesion molecule LFA-1, demonstrating the capacity for migration of these cells. These CD8+ effector cells are suspected to be CTLs and may be responsible for the favorable prognosis of indolent, primary CTCL. Interestingly, a stage-dependent decrease in T-cell activation antigen expression was observed, suggesting the development of a lack in tumor surveillance in advanced MF stages. Further investigations are necessary to verify whether any of the parameters determined are of predictive value for prognosis and response to therapy in CTCL.

Adult↗
PubMed1997

ANP protects against reoxygenation-induced hypercontracture in adult cardiomyocytes.

It was investigated whether atrial natriuretic peptide (ANP) or the related peptide urodilatin can be used for protecting cardiomyocytes against reoxygenation-induced hypercontracture. Isolated ventricular cardiomyocytes (from adult rats) were used as the experimental model. When the cells were submitted to substrate-free anoxia (135 min) and subsequent reoxygenation (30 min), the onset of reoxygenation provoked their hypercontracture. It was studied whether the temporary presence of ANP or urodilatin (1 nM to 1 microM) or 8-bromo-guanosine 3',5'-cyclic monophosphate (8-BrcGMP; 1 microM to 1 mM) during the last 15 min of anoxia and the first 15 min of reoxygenation prevented hypercontracture. It was found that ANP (1 microM) prevented hypercontracture in 82 +/- 8% (SD), urodilatin (1 microM) in 80 +/- 9%, and 8-BrcGMP (1 mM) in 72 +/- 10% of the cells (n = 40 cells). When ANP (1 microM) was added during the last 15 min of anoxia and the first 15 min of reoxygenation, the cellular concentration of cGMP increased from 0.41 +/- 0.04 to 2.80 +/- 0.81 pmol/mg protein (n = 6 cultures). The results show that the reoxygenation-induced hypercontracture in cardiomyocytes can be attenuated by the temporary presence of the stimulators of particulate guanylate cyclase, ANP or urodilatin.

Aerobiosis↗
PubMed1997

[Primary fallopian tube carcinoma. Report of a single case with review of the literature].

With an incidence of 0.1-1.0% of all genital malignancies, primary fallopian tube carcinoma is an extremely uncommon neoplasm of the female genital tract. We report a 58-year-old postmenopausal woman with primary fallopian tube carcinoma confined to the right fallopian tube in primary stage pT2a pN0 G3 M0, who is alive without evidence of disease 2 years after abdominal hysterectomy, bilateral adnexectomy, omentectomy and lymphonodectomy followed by an adjuvant cisplatin (70 mg/m2) and treosulfan (5 g/m2) chemotherapy. An accompanying literature review indicates that clinical signs and symptoms of fallopian tube neoplasms are usually nonspecific and include lower abdominal pain. The primary treatment remains surgical resection followed by adjuvant chemotherapy or radiation. Prognosis is poor, although long-term survivors have been reported.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

Functional interaction between K(ATP) channels and the Na(+)-K(+) pump in metabolically inhibited heart cells of the guinea-pig.

1. Transmembrane current through ATP-regulated K(+) channels (IK(ATP)) was measured in ventricular heart cells of the guinea-pig in the whole-cell and cell-attached patch configurations under conditions of metabolic poisoning with the mitochondrial uncoupler 2,4-dinitrophenol (DNP). 2. Maintained exposure of the cells to DNP resulted in a transient appearance of whole-cell IK(ATP) When IK(ATP) had reached several nanoamps, blocking the forward-running Na(+)-K(+) pump with 0.5 mM strophanthidin decreased IK(ATP) after a delay. The time course of this decrease could be described by a single exponential function, which yielded a time constant(T)of 4.51+/- 1.89 s (n=8). 3. Hyperpolarization from 0 mV to -100 or -150 mV for 2 s caused IK(ATP) (measured at 0 mV) to decrease by 34.2 +/- 14.1 % (n = 8) and 37.6 +/- 9.4% (n = 8), respectively. After the hyperpolarizing pulse, IK(ATP) returned to its higher initial level within a couple of seconds. 4. Driving the pump backwards by removing the extracellular K(+) ions caused the permanent disappearance of DNP-induced IK(ATP). 5. Application of 0.5 mM strophanthidin in the absence of external K(+) ions induced a transient increase in IK(ATP), as did washing out the glycoside (n = 5). 6. When pump action was inhibited by using Na(+), K(+)-free Tyrode solution (see Methods) in the bath, strophanthidin did not have a comparable direct effect on IK(ATP). 7. In cell-attached patches, strophanthidin applied via the bath caused a reduction in IK(ATP) with a similar time course to that in whole-cell experiments. This suggests that the interaction between the pump molecules and the K(ATP) channels is not restricted to closely neighbouring molecules. 8. The data support the hypothesis that [ATP] at the cytosolic face of the membrane may drop to practically zero, thereby passing an 'ATP window' in which the channels first open and then close, and that the submembrane [ATP] is readily controlled by the cytosolic [ATP].

2,4-Dinitrophenol↗
PubMed1996

Sulfogriseofulvin derivatives. synthesis by [4 + 2]cycloaddition, structure, properties, crystal structure analysis, and antifungal activity of spiro[1,3-benzoxathiole-2,1'-cyclohex-2'-en]-4'-one 3,3-dioxides.

Syntheses of substituted, especially of fluoro substituted benzoxathiole 1,1-dioxides, are described. These derivatives were transformed via the Peterson olefination into substituted 2-alkylidene derivatives 27. Diels-Alder reactions of 27 with 1,1-dimethoxy- and 1-methoxy-3-trimethylsiloxy-1,3-butadiene (30, 32) gave sulfone analogues 31 of griseofulvin (named sulfogriseofulvins). From Z-27, a number of cis-isomers with the relative stereochemistry of griseofulvin (cis-31) was prepared, and from E-isomers of 27, compounds (trans-31) with relative stereochemistry of epigriseofulvin were obtained. Some related compounds (33, 38) are synthesized by slight modifications. The stereochemistry is established by spectroscopic methods and crystal structure analyses. The compounds 31 were tested against three species of dermatophytes. The biological activities were all significantly lower than that of griseofulvin.

Antifungal Agents↗
PubMed1996

Isolation of a metal-binding protein from ovaries of dab (Limanda limanda L.) distinct from metallothionein: effect of cadmium exposure.

Metal-binding proteins were isolated from ovaries of dab (Limanda limanda L.) caught in the North Sea. Separation of the heat-treated cytosolic fraction of dab ovaries by gel-filtration chromatography revealed the presence of a major zinc-binding protein with a low-molecular-weight of 10,000-12,000 Da, similar to mammalian metallothionein (MT). The metal-binding protein was analyzed by anion-exchange chromatography and by reversedphase high-performance liquid chromatography. The metal-binding protein from dab ovaries consists of one major isoform. Zinc could be displaced from the isoform by a saturation of the extract with cadmium, leading to altered retention of the protein at the RP column. In a laboratory experiment, dabs were treated intraperitoneally with cadmium (0.5 and 1.5 mg/kg body wt). In contrast to hepatic dab MT, the metal-binding protein in ovaries was not inducable by cadmium; however, dose-dependent amounts of cadmium were bound to the ovarian protein after the metal exposure. The amino acid composition was different from that of mammalian MT. The results suggest that the metal-binding protein in dab ovaries is possibly involved in ovary development and can be affected by cadmium exposure.

Animals↗
PubMed1996

Contribution to the mechanism of chromate nephrotoxicity in developing rats: EPR investigations.

The effect of 2 mg and 1 mg Na2Cr2O7 (Cr)/100 g body wt. on renal function was investigated in 10- and 55-day-old rats, respectively. These doses were followed by equal Cr concentrations in the renal tissue of both age groups. Confirming previous data we found lower nephrotoxicity in young than in adult rats. The concentration of glutathione (GSH) and the activity of glutathione reductase (GSSG reductase) in renal tissue of adult rats were diminished by buthionine sulfoximine (BSO) and lomustine (CCNU) administration, respectively. In these animals Cr nephrotoxicity was decreased significantly. Lower nephrotoxicity was accompanied by slower disappearance of Cr(VI) from renal tissue homogenate in vitro. The time course of Cr(VI) reduction demonstrated by the signal intensity of Cr(V), as recorded by electron spin resonance (EPR) spectroscopy in the supernatant of renal tissue homogenate, enabled us to follow the reduction of Cr(VI) to Cr(III) via Cr(V). Maximally reached Cr(V) concentrations lowest in young rats, did not differ significantly in adult control and BSO and BSO + CCNU treated rats. Further reduction of Cr(V) to Cr(III) which appeared most rapidly in adult rats, was delayed by pretreatment with BSO and CCNU. From our results we concluded that (1) reduction of Cr(VI) was more related to the concentration of GSH than to the activity of GSSG reductase, (2) the formation of Cr-GSH-complexes with GSH oxidation seemed to be the first step of Cr(VI) metabolism, and (3) the stabilization of reactive Cr(V) by GSH seemed to be decisive for the preventive effect of BSO and CCNU as well as for age differences in chromate nephrotoxicity.

Age Factors↗
PubMed1996

IL-7 mRNA is not overexpressed in mycosis fungoides and pleomorphic T-cell lymphoma and is likely to be an autocrine growth factor in vivo.

Interleukin-7 (IL-7) is thought to be a growth factor for cutaneous T-cell lymphoma (CTCL) since it has been shown that IL-7 transgenic mice develop a cutaneous disorder characterized by enhanced T-cell proliferation with progression to malignancy and that in vitro growth of Sézary cell lines is IL-7 dependent. However, no direct in vivo evidence exists for the involvement of IL-7 in the pathogenesis of CTCL. Therefore, we examined IL-7 mRNA expression in skin biopsies from patients with mycosis fungoides (MF) (n = 20) and pleomorphic T-cell lymphoma (n = 5). By semiquantitative RT-PCR, IL-7 mRNA was not detectable in any of the CTCL samples, or in normal human skin (n = 8) or in skin from patients with psoriasis (n = 7) or atopic dermatitis (n = 5). In contrast, IL-7 mRNA was detected in a biopsy from a kidney allograft transplant, in normal keratinocytes under various culture conditions and in several cell lines. Interestingly, using a highly sensitive nested PCR, IL-7 mRNA was detectable in all specimens tested, but there was no indication of IL-7 overexpression in MF then analysing lesions of patch, plaque or tumour stages. In contrast, increasing CD3 expression was found, which was most likely a consequence of the enhanced density of malignant T cells in advanced tumour stages. In summary, by the use of semiquantitative RT-PCR we were not able to detect IL-7 overexpression in MF or pleomorphic T-cell lymphoma. This indicates that IL-7 is probably not an autocrine growth factor in these CTCLs.

Adult↗
PubMed1996

Influence of exogenous and endogenous acth on adrenal cortex activity in calves during the early postnatal period.

A study was carried out on 66 black-and-white calves during the period from birth (day 0) to day 21 of life. Blood plasma adrenocorticotrophic hormone (ACTH) and cortisol concentrations were determined by radio-immunoassay and the influence of exogenous and endogenous ACTH on adrenocortical activity assessed. An ACTH-induced adrenal cortex response was observed as early as day 0, whereas a definite relationship between ACTH and cortisol concentrations emerged in the second week of life. It is concluded that the pituitary-adrenal axis is blocked during the first week of life and this effect seems to be related to high cortisol concentrations and an elevated reactivity threshold of the adrenal ACTH receptors.

Adrenal Cortex↗
PubMed1996

The effect of brochure use versus therapist teaching on patients performing therapeutic exercise and on changes in impairment status.

BACKGROUND AND PURPOSE: The purpose of this study was to investigate whether the mode of teaching exercises (use of brochures versus therapist teaching) affects whether patients correctly perform the exercises and whether it affects changes in impairment. SUBJECTS: Eighty-seven patients (33 women, 54 men) with neck pain and low back pain were examined. The average age was 48 years (SD = 12.7, range = 21-67). METHODS: Two groups of patients were analyzed. The supervised (physical therapist-instructed) group (n = 47) exercised under the supervision of a physical therapist, whereas the brochure group (n = 40) received their instructions only from one of three brochures. A rating scale was used to assess the correctness of exercise performance. Muscle status was registered using a standardized procedure for determination of muscle force and length. Pain severity was determined by means of a visual analogue scale. RESULTS: On the rating scale evaluating the correctness of exercise performance at follow-up, the patients in the supervised group performed better than the patients in the brochure group. In addition, there was a strong correlation between the quality of exercise performance and decrease in pain. CONCLUSION AND DISCUSSION: Exercises learned only from a brochure without being monitored by a physical therapist were done properly by only about half of the patients and appeared to result in fewer improvements in impairments.

Adult↗
PubMed1996

Phylogenetic positions of Desulfofustis glycolicus gen. nov., sp. nov., and Syntrophobotulus glycolicus gen. nov., sp. nov., two new strict anaerobes growing with glycolic acid.

The glycolate-oxidizing, sulfate-reducing bacterium strain PerGlyS and the syntrophically glycolate-oxidizing bacterium strain FlGlyR were studied with respect to their phylogenetic relationships on the basis of in vitro amplification and direct sequencing of 16S rRNA-encoding DNA. Strain PerGlyS clustered with representatives of the delta subclass of the class Proteobacteria, close to "Desulforhopalus vacuolatus" but sufficiently distinct to preclude its assignment to this genus. These organisms, together with Desulfobulbus propionicus, represent a phylogenetic subgroup among members of the delta subclass of Proteobacteria. Strain FlGlyR was found to cluster with the gram-positive bacteria with low-G + C DNA, and Desulfitobacterium dehalogenans and Desulfotomaculum orientis are its closest relatives. Other species of the genus Desulfotomaculum are phylogenetically only moderately closely related to these organisms. These results necessitate the establishment of new genera and species for these two strains. Strain PerGlyS was designated the type strain of Desulfofustis glycolicus gen. nov., sp. nov., and strain FlGlyR was designated the type strain of Syntrophobotulus glycolicus gen. nov., sp. nov.

Bacteria, Anaerobic↗
PubMed1995

Ribosomal DNA phylogeny of the major extant arthropod classes and the evolution of myriapods.

The evolutionary relationships among arthropods are of particular interest because the best-studied model system for ontogenetic pattern formation, the insect Drosophila, is a member of this phylum. Evolutionary inferences about the developmental mechanisms that have led to the various designs of the arthropod body plan depend on a knowledge of the phylogenetic framework of arthropod evolution. Based on morphological evidence, but also on palaeontological consideration, the sister group of the insects is believed to be found among the myriapods. Using nuclear ribosomal gene sequences for constructing a molecular phylogeny, we provide strong evidence that the crustaceans and not the myriapods should be considered to be the sister group of the insects. Moreover, the degree of sequence divergence suggests that the diversification of the myriapods occurred during the Cambrian. Our findings have general implications for the course of land colonization by the different arthropod groups, as well as for the interpretation of primitive and derived features of arthropod morphology.

Animals↗
PubMed1995

Electron transport phosphorylation driven by glyoxylate respiration with hydrogen as electron donor in membrane vesicles of a glyoxylate-fermenting bacterium.

The syntrophically glycolate-fermenting bacterium in the methanogenic binary coculture FlGlyM was isolated in pure culture (strain FlGlyR) with glyoxylate as sole substrate. This strain disproportionated 12 glyoxylate to 7 glycolate, 10 CO2, and 3 hydrogen. Glyoxylate was oxidized via the malyl-CoA pathway. All enzymes of this pathway, i.e. malyl-CoA lyase/malate: CoA ligase, malic enzyme, and pyruvate synthase, were demonstrated in cell-free extracts. Glycolate dehydrogenase, hydrogenase, and ATPase, as well as menaquinones as potential electron carriers, were present in the membranes. Everted membrane vesicles catalyzed hydrogen-dependent glyoxylate reduction to glycolate [86-207 nmol min-1 (mg protein)-1] coupled to ATP synthesis from ADP and Pi [38-82 nmol min-1 (mg protein)-1)]. ATP synthesis was abolished entirely by protonophores or ATPase inhibitors (up to 98 and 94% inhibition, respectively) indicating the involvement of proton-motive force in an electron transport phosphorylation driven by a new glyoxylate respiration with hydrogen as electron donor. Measured reaction rates in vesicle preparations revealed a stoichiometry of ATP formation of 0.2-0.5 ATP per glyoxylate reduced.

Adenosine Triphosphate↗
PubMed1995

[Erythropoietin therapy during frequent autologous blood donations. Dose-finding study].

Avoidance of homologous blood products and patients' demand for preoperative autologous blood donation programs are increasing. As many of these patients are older, with a compromised cardiovascular system and a slow response of the erythropoietic system when anemia occurs, the feasibility and benefit of autologous blood donation is often limited. Augmentation of preoperative blood donation by therapy with recombinant human erythropoietin (rHuEPO) has been described in animal models and in patients. METHODS. In a multicenter, controlled, randomized trial, 49 patients scheduled for orthopaedic or vascular surgery received 0 (control group, n = 9), 200 (n = 10), 300 (n = 11), 400 (n = 10) or 500 (n = 9) U/kg rHuEPO (Erypo, Cilag, Sulzbach, distributor Fresenius, Oberursel, Germany) subcutaneously twice a week for 3 weeks while every week 450 ml blood was collected. Iron sulphate 100 mg was prescribed orally twice a day. Patients were ineligible if they had uncontrolled hypertension, recent myocardial infarction, haematological disorders or a history of seizures. Blood donation had to be cancelled if the haematocrit was below 30%. RESULTS. There was a significant (ANOVA) drop of the haematocrit value only in the control group, and end-point values for haematocrit and haemoglobin were significantly elevated in the 400 and 500 U/kg groups compared with the control group (Table 9). DISCUSSION. The erythropoietic stimulus of phlebotomy for autologous blood donations is often not efficient enough to guarantee a constant haematocrit. Lowering of the preoperative haematocrit jeopardizes the aim of avoidance of homologous blood transfusions. rHuEPO increased the efficiency of autologous blood collections, as predonation haematocrit values could be preserved in the high-dosage groups. As a consequence, homologous transfusions could be avoided. However, there were broad interindividual differences in the erythropoietic response, possibly due to limitations in iron availability. Adverse effects of rHuEPO therapy, such as hypertension, thrombosis or neurologic disorders, are mostly reported in patients with terminal kidney failure. No such disturbances were observed in the present study. CONCLUSION. rHuEPO ameliorates the preoperative decrease of haemoglobin and haematocrit values due to autologous blood donations in a dose-related fashion. The individually adjusted dosage of rHuEPO and iron supplementation merits further investigation.

Blood Donors↗
PubMed1995

[Implantation of a phrenic stimulator in central respiratory paralysis].

Neoplastic or traumatic lesions of the brain stem or the upper spinal cord frequently cause respiratory insufficiency necessitating permanent mechanical ventilation. If the integrity of the diaphragm and its nerves is not affected, adequate ventilation can be achieved by electric stimulation of the phrenic nerves. Diaphragm pacing systems mean the patients can be independent of ventilator treatment. This is a psychological advantage for the patient, giving him or her the option of living in less specialized medical care units and perhaps even at home. CASE REPORT. We report the case of a 47-year-old man with a brain stem tumour, which was resected in large pieces. During the postoperative period an increasingly severe respiratory insufficiency developed, which finally made continuous mechanical ventilation necessary. After the viability of the phrenic nerves and contractility of the diaphragm had been shown by direct stimulation of the nerves to be still intact, it was decided that a diaphragm pacer system should be implanted. A "Diaphragm Pacer System S232 G" (Avery Laboratories, Glen Cove, N.Y., USA: external transmitter, antenna, implanted electrode and receiver) was implanted. Using a supraclavicular approach, phrenic nerve electrodes were placed around each nerve and connected with subcutaneous implants of radio signal receivers. Six days after implantation phrenic nerves were stimulated for a first short period. External antenna loops were taped to the skin over the implanted receiver sites (Fig. 3). The impulses produced by the transmitter were delivered via these antenna loops and led to contraction of the diaphragm, providing almost normal respiration. The duration of stimulation was increased stepwise from 1 h a day to full-time stimulation. Three weeks after implantation of the diaphragm pacer system the patient could be totally weaned from mechanical ventilation. After a further 2 weeks it was possible to discharge him from the intensive care unit, and he was then transferred to a rehabilitation centre.

Brain Neoplasms↗