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Biomedical subjects

W Vogel

Publications and source records attributed to W Vogel.

At least 397 records · Page 22Linked to original sources
PubMed1985

[Morphine metabolism in critical patients with need-directed peridural morphine infusion for the management of postoperative pain].

For constant analgesia after abdominal surgery, 34 patients (Group I) and 14 patients under intensive care (Group II) received epidural morphine infusions at mean hourly rates of 0.23 +/- 0.04 mg morphine in the first hour to 0.01 +/- 0.0 mg in the 50th hour, and 1.55 +/- 0.26 mg in the first hour to 0.20 +/- 0.08 mg in the 50th hour, respectively, after an initial bolus injection of 2 mg morphine. Whereas in Group I metabolized morphine immunoreactivity reached a plateau within 20 minutes which lasted until 8 p.m. on the operation day, in Group II a far higher plateau (p less than 0.001) was attained,--but only after some hours--which lasted until 8 p.m. on the first postoperative day. In the course of the treatment, concentrations of metabolized morphine immunoreactivity in serum and in urine decreased in both groups.

Antibodies↗
PubMed1985

Interface reactions between machinable bioactive glass-ceramics and bone.

A new biomaterial for bone substitution, a "machinable bioactive glass-ceramic" has been developed. The material contains two main crystal phases, mica and apatite, and is therefore machinable and bioactive. It has the advantage to be workable by the surgeon, if necessary, during operation. The preparation method of this glass-ceramic is described. Different types of the material can be produced in dependence of the composition, nucleation, and crystallization of the basic glass. In vivo and in vitro investigations showed a characteristic solubility of the material. A Ca-phosphate-rich interface layer with apatite crystals (from the basic glass-ceramic) and a thickness of about 5-10 micrometers grows as solid-state reaction between glass-ceramic and bone. This interface reaction is interpreted as a chemical process which includes a slight solubility of the glass-ceramic and a solid state reaction between the stable apatite crystals in the glass-ceramic and the bone.

Aluminum Silicates↗
PubMed1985

Do the frequencies of sister chromatid exchanges in endoreduplicated mitoses provide a measure for lesion persistence and repair?

Endoreduplication was induced in V 79 cells using Colcemid. The concentration of Colcemid necessary to induce endoreduplication is about 1000 times higher than that needed to arrest mitoses or to induce ordinary tetraploid cells. Diplochromosomes with sister chromatid differentiation were obtained by adding BrdU for the duration of one cell cycle prior to the induction of endoreduplication. The induction of endoreduplication with Colcemid had no influence on the frequency of sister chromatid exchanges (SCEs). Treating the cultures with mitomycin C (MMC) before adding BrdU increased the percentage of endoreduplicated mitoses and also led to marked SCE induction. In the diplochromosomes, the frequencies of both twin SCEs (first cycle) as well as single SCEs (second cycle) were increased. It was also found that the SCE frequencies in mitoses after endoreduplication were lower than the values found in diploid and ordinary tetraploid metaphases of the same preparation. The possible conclusions concerning the lifetime of SCE-inducing lesions and the influence of repair processes are discussed.

Animals↗
PubMed1985

Manifestation of the fragile site Xq27 in fibroblasts. IV. Clones from a heterozygous female do not manifest this site homogeneously on either the early or late replicating X chromosome.

Fibroblasts from a heterozygous carrier for the Martin-Bell syndrome, who manifests the fragile site Xq27, were cloned to separate the population carrying the primary defect on the active X chromosome from the population with this defect on the inactive X. Clones with this defect on the active X manifest the fra(X)(q27) whereas clones from the other population are fra(X)-negative (Steinbach et al. 1983b). In this project, the replication status of the X chromosome manifesting the fra(X)(q27) was studied in seven clones with this defect on the active X. The results obtained on the clones were very similar to the results obtained from uncloned fibroblasts and lymphocytes. In the clones the fragile site was found manifested on the early replicating X in 73 cells and on the late replicating X in four cells. Since the defect is located on the active X chromosome of these cells the manifestation of the fragile site on the late replicating X suggests that the defect and the fragile site cannot be identical. It is concluded that there is no obligate synteny of this defect and the manifested fragile site.

Chromosome Fragile Sites↗
PubMed1985

Characterization of chromosome replication during S-phase with bromodeoxyuridine labelling in Chinese hamster ovary and HeLa cells.

Chinese hamster ovary (CHO) and HeLa cells were successively pulse labelled at 1-h intervals after the cultures were synchronized at the end of G1 (monitored by flow cytometry). The metaphases analysed afterwards showed R-type replication patterns after 1-h pulses during the early S-phase (SE; from h 1-5 after release) and replication of G- and C-bands in late S-phase (SL: from h 6-8 after release). The transition from SE to SL is abrupt, constituting a sudden switch of replication between different types of chromatin as has been described for human lymphocytes. The differences between these two cell lines and earlier results reported on a V79 Chinese hamster cell line and on normal diploid human and Chinese hamster fibroblasts are discussed.

Animals↗
PubMed1985

Characterization of mitoses with sister chromatid differentiation (SCD) and consequences for the analysis of proliferation kinetics and sister chromatid exchanges in asynchronously growing cells.

Labeling cells with bromodeoxyuridine (BrdU) permits the differentiation of mitoses of the first, second, and third generation after the addition of BrdU. The term "second mitoses" is used for those cells which have incorporated BrdU for two S-phases and which exhibit sister chromatid differentiation (SCD). However, SCD can also be obtained if the cell was in S-phase at the time of BrdU-addition and had already replicated part of its DNA. Such cells with incomplete BrdU-substitution in the first S-phase can only be differentiated from completely substituted ones by the quality of the SCD and are usually also grouped as "second mitoses" in the evaluation of experiments. Due to the heterogeneity of the evaluated "second mitoses", the determination of proliferation delay and the incidence of sister chromatid exchange-induction can depend on the time of chromosome preparation.

Animals↗
PubMed1985

Electrophysiological and neurobiochemical evidence for the blockade of a potassium channel by dendrotoxin.

The effects of dendrotoxin (DTX), a toxic peptide from Dendroaspis angusticeps venom, were studied electrophysiologically on peripheral frog nerve fibres, and biochemically on large synaptosomes from rat brain. On nerve fibres, DTX reduced the amplitude and prolonged the duration of the action potential; even at 0.1 nmol/l DTX produced significant effects. Maximum block of potassium currents occurred at about 30 nmol/l. Turning on of the remaining current was slowed. Reversibility was incomplete. The reduction of potassium currents was between 31% and 85% at 85 nmol/l DTX (n = 8). The remainder appeared to be resistant to DTX. Sodium channels were not affected. On large synaptosomes DTX (above 1 nmol/l) produced a slight depolarization, indicated by an outward shift of the lipophilic cation tetraphenylphosphonium, and promoted the release of radioactivity after preloading with [3H] GABA. DTX had similar potency but lower efficacy in this respect than sea anemone toxin II (ATX II). In contrast to the effects of ATX II, those due to DTX were only partially inhibited by tetrodotoxin. The actions of 4-aminopyridine resembled those of DTX, but the latter was about 500 times more potent. The electrophysiological data provide direct evidence for blockade of a potassium channel by DTX. This action is sufficient to explain the biochemical observations, although additional effects on synaptosomes cannot be excluded.

Action Potentials↗
PubMed1985

Three functions of sodium channels in the toad node of Ranvier are altered by trimethyloxonium ions.

Voltage-clamped nodes of Ranvier of the toad Xenopus laevis were treated with trimethyloxonium ions (TMO) which are known to methylate carboxyl groups. TMO did not affect potassium channels but the sodium system was modified in three ways: a) the current was reduced, b) channels were rendered insensitive to tetrodotoxin (TTX) and c) the inactivation of all channels, TTX-resistant or not, was slowed in a potential range between 50 and 110 mV. Steady-state inactivation, however, was not changed. Presence of 100 nM TTX during TMO treatment prevented the production of TTX-resistant channels but did not hinder current reduction and slowing of inactivation. The TTX-resistant sodium channels were blocked by protons and had normal relative permeabilities to alkali metal ions. Repeated application of TMO further decreased the current and increased the relative amount of TTX-resistant channels; the slowing of inactivation, however, was quantitatively terminated after the first TMO treatment. It is concluded that the sodium channel contains at least three TMO-modifiable groups, which probably are carboxyl groups.

Animals↗
PubMed1985

[Value of surgical hysteroscopy in the treatment of myomas and intracavitary fibrous polyps. Evaluation of 26 operations].

Out of a total of 121 hysteroscopies carried out in this unit between December 1981 and June 1984, 26 were operative hysteroscopies. Each of these procedures consisted in removing intra-uterine structures (that could not be removed with a curette) under visual control. All cases had a normal sized or slightly enlarged uterus. There were 7 patients aged 41 years or younger and 19 older than 41. The endoscope used was the "bayonet" Wolf apparatus which is 7 mm in diameter and has two separate canals; one for insufflation and the other for introducing the 3 mm biopsy forceps. This small punch makes it possible to cut the implantation on uterine wall without needing coagulation. The tissue is then removed using a soft curette or a polyp forceps after the cervix has been further dilated. There was no case in which heavy bleeding occurred during or after the operation. Using this technique we were able to remove 18 fibroid polyps, 13 submucous fibroids (8 smaller than 2 cm in diameter and 5 between 2 and 4 cm), 3 old retained portions of placenta; removal was complete in 21 cases and only partial in 5 cases. Out of these 2 had to have hysterectomy. On the other hand abdominal myomectomy or hysterectomy could be avoided in 11 cases. This series shows how often fibrous polyps and small sub-mucous fibroids can be removed under hysteroscopic control when using this kind of apparatus and a relatively simple technique.

Adult↗
PubMed1985

[Scanning electron microscopy study of cell growth on mechanically produced biovitroceramic and carbon glass in vitro and in vivo].

New machinable glass ceramics were tested for the application in middle ear surgery in vitro and in vivo. This ceramic consists of a glass phase and a glimmer phase. Fibroblasts and epitheloid cells seated on the test material attach to it, spread and form a confluent monolayer. From our findings on the behaviour of cell populations in vitro we can conclude that the implanted material is biocompatible. After implantation into the middle ear of rabbits, irritation-free settling was verified by the existence of a thin epithelium layer and a direct connection between bone and implant. Glass carbon did not yield equally satisfactory results.

Animals↗
PubMed1985

Effect of diethylstilbestrol on the frequencies of sister chromatid exchange in vitro and in vivo.

The influence of diethylstilbestrol (DES) on the SCE frequency was studied in various cell systems (V79, HTC, DON, WI-38, human lymphocytes) differing in their ability to metabolize the two promutagens benzo(a)pyrene and cyclophosphamide as well as after incubation with exogenous metabolic systems (S9 mix and peroxidase/H2O2) and in vivo on cells from the bone marrow of the Chinese hamster. DES concentrations from 10(-6) to 10(-4) M were tested. Slight SCE induction was observed only at the highest concentration (10(-4) M) of DES in human lymphocytes treated with DES for the entire culture period of 72 h and in DON cells. No increase of the SCE rate was determined in the other cell lines and in vivo. The combination with S9 mix or peroxidase/H2O2 also had no influence on the SCE frequency. These findings cast doubt on the assumption that DES is metabolized to a DNA-damaging compound subsequently leading to SCE induction. The positive findings in the SCE test are more likely to be products of an indirect and rather unspecific effect.

Animals↗
PubMed1984

[Initial clinical experiences with allotransplantation of the pancreas].

Since 1979 7 pancreas transplantations have been performed in 8 type I diabetics. 5 of these 7 recipients had already been dialysed; 2 were awaiting their first dialysis. Furthermore, diabetes had caused severe retinopathy in 5 patients. The pancreas was transplanted simultaneously with a kidney from the same donor in 5 recipients; in 3 cases the pancreas was grafted 16 to 230 days after successful renal transplantation. 1 pancreas graft was removed immediately after revascularisation because of ischaemic damage. While the pancreatic duct was occluded in the first 4 patients, enteric diversion of the pancreatic juice was applied in the next 3 recipients. The first two patients were treated with conventional immunosuppression, whilst all the others received cyclosporin A and low-dose steroids. Small amounts of insulin had to be given initially for a few days in 2 cases, only. 2 grafts were lost due to surgical complications and 3 for immunological reasons. 1 functioning graft had to be removed because the patient was not willing to continue immunosuppression after irreversible rejection of her renal transplant. There was no perioperative death. 2 pancreatic and 5 renal grafts are functioning well at the present time. Technical aspects and problems in the diagnosis of rejection are discussed.

Adult↗