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Biomedical subjects

M Schultz

Publications and source records attributed to M Schultz.

At least 109 records · Page 6Linked to original sources
PubMed1988

Relation between renal and hepatic excretion of drugs: X. Excretion of nalorphine in young and adult rats pretreated with hormones or xenobiotics.

Different processes are involved in renal and hepatic excretion of organic anions and cations. In contrast to our knowledge of anion excretion, information about cation transport in kidney and liver is relatively scarce. In this study, the elimination of nalorphine was investigated to characterize the relation between renal and hepatic excretion of organic cations. Nalorphine is excreted effectively both via kidney and liver. However, its hepatic excretion dominates in adult rats. In young, 20-day-old animals biliary nalorphine elimination is immature and the excreted amounts are significantly lower. Renal excretion of nalorphine is quite similar in rats of both ages. After bile duct ligation renal excretion of nalorphine increases significantly in adult rats whereas it remains unchanged in young ones. Remarkably, after bilateral nephrectomy hepatic elimination of nalorphine is even diminished in both age groups. In further experiments renal excretion of nalorphine could be stimulated in adult rats after repeated administration of trometamol, triiodothyronine, or dexamethasone; these treatments had no consequences on biliary secretion of nalorphine.

Aging↗
PubMed1988

Problems of experimental tumourigenesis by fibrous dusts, especially by asbestos (with regard to stanton's hypothesis).

Asbestos dust has got a very great importance because cancerogenicity is imputed into it in occupational and, perhaps, in common environmental conditions too. The short review deals with general problems in experimenting with fibrous dusts, especially the modes of its application, the transferability of results to human pathology and the cause and pathway of cancerisation by fibres and crystals.

Animals↗
PubMed1988

[Asbestos-induced malignant tumors].

Asbestos had been increasingly used in many applications across numerous industries on account of its particular material properties, including resistance to heat and fire as well as to aggressive chemicals, high mechanical strength, insulation capacity, other physical parameters, and for its low price. World wide asbestos production and processing thus went up from 50 tons to 5.5 million tons per annum, in about 100 years. Widespread application of asbestos as well as of asbestos-containing materials and workpieces together with the understanding that asbestos for its fibrogenicity is capable of causing pulmonary and pleural asbestoses constitute a major challenge for thorough elucidation of related occupational diseases and their relationship with asbestos. This demand is additionally supported in urgency by the cancerogenicity of asbestos potentially leading to malignant diffuse mesotheliomas, bronchial carcinomas, and, obviously, other tumors. In the context of malignant mesotheliomas, emphasis has to be laid on characteristic morphological features, biological behaviours, and asbestos-related aetiology. As bronchial carcinomas have several aetiological backgrounds, answers will have to be found to the questions for which of them may have been fully or partially caused by asbestos and which have not. No differentiation has so far been feasible, in this context, by tumour morphology, including histological typing. After all, when it comes to malignant tumours of other organs, additional epidemiological as well as pathologico-anatomic efforts will have to be made to find out, if and where a given case of tumour growth has coincided with exposure to asbestos.

Asbestos↗
PubMed1988

[Interstitial lung diseases of the interstitial-proliferative type].

The term of "chronic interstitial pneumonia" had been more accurately redefined by Liebow and, subsequently, by Otto and had been subdivided by different pathomorphological phenomena. The interstitial-proliferative type is of particular interest, in this context. Reported in this paper is the bioptic histopathological pattern of 15 patients with interstitial lung disease of the interstitial-proliferative type, with these findings being correlated to clinical symptoms. A distinction is made between an independent form in its own right and a histologically identical interstitial phenomenon accompanying other pulmonary diseases, primarily in concomitance with lung cancer, and recordable also from postmortem investigations. Interstitial-proliferative inflammations are adequately controllable by antibiotics.

Adult↗
PubMed1987

Cobra venom factor and human C3 share carbohydrate antigenic determinants.

As tools to study structural relationships of cobra venom factor (CVF) and human complement component C3, murine monoclonal antibodies to CVF were produced. In this paper we describe two of these monoclonal anti-CVF antibodies designated GV1.8 and GV1.10, both of which bind to carbohydrate epitopes. On immunoblotting, antibody GV1.8 binds to both the alpha- and beta-chains of CVF, whereas antibody GV1.10 binds only to the alpha-chain of CVF. After enzymatic deglycosylation of CVF with N-glycanase (peptide-N4-(N-acetyl-beta-glucosaminyl) asparagine amidase), both antibodies lose their ability to bind to the deglycosylated protein. Additionally, the free oligosaccharide chains of CVF are able to inhibit the binding of antibodies GV1.8 and GV1.10 to CVF on enzyme-linked immunosorbent assay, further demonstrating their carbohydrate specificity. Both monoclonal antibodies to CVF cross-react with human C3. Antibody GV1.8 binds to both chains of human C3 indicating that the shared antigenic epitope present on the two glycosylated chains of CVF is also present on the two chains of human C3. Antibody GV1.10 cross-reacts only with the beta-chain of human C3 which is the homologous chain to the alpha-chain of CVF. After enzymatic deglycosylation of human C3 by N-glycanase, both antibodies lose their ability to bind to the deglycosylated protein consistent with the carbohydrate nature of the recognized epitopes. These results indicate that CVF and human C3 share carbohydrate epitopes on their homologous and nonhomologous chains.

Carbohydrates↗
PubMed1986

[Pharmacodynamics of vecuronium in infants during intravenous induction of anesthesia with ketamine].

The pharmacodynamic effects of vecuronium in children aged 1 to 6 years were investigated after intravenous induction of anaesthesia with ketamine, using an initial dose of vecuronium of 0.08 mg/kg body wt. 0.1 mg/kg body wt. The degree of neuromuscular blockade was determined by measuring the contraction force of the m. adductor pollicis after supramaximal stimulation of the ulnar nerve using an electromechanical device. The results (median, chi min and chi max) were as follows. For the initial dose 0.08 mg/kg body wt., the onset time was 150 s (110-360 s); total blockade: 5 of 9 children, D25 (duration of 25% recovery) 13 min (10-31); RI (recovery index): 8.5 min (6.0-14.5); D90 (duration of 90% recovery): 27 min (20-44). For the initial dose of 0.1 mg/kg body wt., the onset time was 135 s (80-300); total blockade: all children, D25: 19.5 min (12-32.5); RI: 8.75 min (6.5-13.5); D90 35 min (22-45). Only the D25 was significantly shorter using an initial dose of 0.08 mg/kg body wt. For a total blockade, a higher dose of vecuronium is necessary using intravenous induction of anaesthesia compared with previously described inhalation techniques. Even with the high dosage, recovery from neuromuscular blockade is so rapid in this age group that it can be used even for short operations without reversal.

Anesthesia, Intravenous↗
PubMed1985

[Hemodynamics and morphologic changes following stroma-free hemoglobin solutions in animal experiments].

Hemodynamics and pathomorphological signs after infusion of a stroma-free hemoglobin solution with defined stroma rest contend were registered in 24 minipigs. The small intravascular persistence and potential toxicity were the disadvantages of the solution. We noted a falling down of the central venous pressure and an ascent of the middle arterial pressure so the total peripheral resistance.

Acid-Base Equilibrium↗
PubMed1985

Explorative studies on karyometric frequency distributions. II. Approximation using normally distributed curves versus median interpolation.

An approximation using normally distributed curves and a median interpolation were applied to frequency distributions of nuclear size with one maximum. Both methods gave the same results as far as the positions of the curves on the axis of nuclear volume classes were concerned. Further detailed information on the course of the curves by the median interpolation, however, may be falsified by artificial differences due to the interpolation.

Animals↗
PubMed1984

The pharmacokinetics of heroin in patients with chronic pain.

We measured blood concentrations of heroin and its active metabolites, 6-acetylmorphine and morphine, serially in 11 patients with chronic pain (9 of whom had cancer) after intravenous injection, intravenous infusion, intramuscular injection, and an oral dose of heroin hydrochloride. Parenteral heroin provided measureable blood levels of heroin, 6-acetylmorphine, and morphine. Blood levels of heroin and 6-acetylmorphine reached their maximal concentrations within minutes and were cleared rapidly. The mean half-life of heroin (+/- S.D.) after intravenous injection or infusion was only 3.0 +/- 1.3 minutes, and the mean clearance of heroin from the blood at apparent steady state was 30.8 +/- 2.1 ml per kilogram of body weight per minute. Morphine levels rose more gradually, and morphine was cleared much more slowly. Oral administration of heroin resulted in measurable blood levels of morphine but not of heroin or 6-acetylmorphine. The amount of circulating morphine provided by an oral dose of heroin was only 79 per cent of that available from an equal amount of morphine. We conclude that heroin is a pro-drug that serves to determine the distribution of its active metabolites. Parenteral heroin is rapidly converted to 6-acetylmorphine, which contributes to rapid pain relief. Oral heroin is converted to morphine and appears to be an inefficient means of providing morphine to the systemic circulation.

Administration, Oral↗
PubMed1984

Problems in fitting a cosine curve.

In fitting of cosine curves latent experimental inequalities due to a serial effect have to be excluded. Though cosinor analysis may be sufficient then, inclusion of biological time, i.e. not fitting values to time but to a function of time, will lead to further improvement.

Animals↗
PubMed1984

[Note on the smoothing of time series].

For smoothing of time series instead of the method introduced by Kulenkampff and Kolb as a simple mathematical procedure weighted moving averages are proposed.

Animals↗
PubMed1983

Karyometric investigation on circadian rhythmic changes in the periportal and perivenous zones of the acinus of the rat liver.

In untreated adult male albino rats changes in nuclear volume within the periportal and the perivenous zones of the liver acinus were measured during a full day and night cycle. Only the perivenous zone displayed circadian rhythmic changes as expressed in the sinus-like course of the nuclear volume-distribution graph (polynomial) with a maximum between 16.00 h and 18.00 h and a minimum at 8.00 h. In all groups studied zonal heterogeneity of the means of nuclear volume and the percent-distribution graphs of nuclear volume classes were retained during the full cycle. Within each zone, however, distribution curves of nuclear volume classes were homogeneous indicating an equally directed trend in time-dependent changes in nuclear volume.

Animals↗
PubMed1983

Evidence from opiate binding studies that heroin acts through its metabolites.

The relative affinity to opiate receptors of heroin, 6-acetylmorphine and morphine was estimated by determining their ability to displace specifically bound 3H-naltrexone from rat brain opiate binding sites. In vitro hydrolysis of heroin to 6-acetylmorphine was monitored in the binding assay filtrate by use of a quantitative HPLC procedure. The rate of heroin hydrolysis was significantly slower at 0 degrees C than at 37 degrees C. The displacement of 1 nM 3H-naltrexone by unlabeled ligand at concentrations ranging from 7 to 500 nM was measured at 0 degrees C for 120 minutes, yielding IC50 values of heroin = 483 nM, 6-acetylmorphine = 73 nM and morphine = 53 nM. When the binding data for heroin were recalculated to include the displacement that could be attributed to the 6-acetylmorphine derived from heroin degradation during the incubation, all of the apparent heroin binding was accounted for by the 6-acetylmorphine. These results are consistent with previous reports of the low binding affinity of morphine congeners (e.g., codeine) that lack a free phenolic 3-hydroxyl group and support the view that heroin is a prodrug which serves to determine the distribution of its intrinsically active metabolites, 6-acetylmorphine and morphine.

Animals↗
PubMed1983

Eclipse of coxsackievirus infectivity: the restrictive event for a non-fusing myogenic cell line.

Coxsackieviruses A2, A5 and B3 did not replicate in L8CL3-U cells (a non-fusing variant of the rat L8 myogenic cell line) although these cells possessed a common receptor for coxsackieviruses A2 and A5, and a different receptor for coxsackievirus B3. The restriction in replication was identified as a block in viral eclipse, since 6 M-LiCl treatment permitted recovery of the coxsackievirus A2 inoculum from L8CL3-U cells after 2 h at 37 degrees C, and the cells could be transfected by viral RNA. Cellular fusion which was induced in L8CL3-U cultures by herpes simplex virus type 1 (HF strain) facilitated coxsackievirus A2 and A5 replication. Differentiating myogenic L8 cells acquired full susceptibility to infection concurrently with the appearance of acetylcholine receptors, the muscle-specific isoenzyme of creatine phosphokinase, prominent myotube formation and the acquired capacity of the cells to eclipse virus.

Animals↗