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Biomedical subjects

G Merker

Publications and source records attributed to G Merker.

At least 37 records · Page 2Linked to original sources
PubMed1983

First experimental and clinical results of isolated liver perfusion with cytotoxics in metastases from colorectal primary.

In two patients suffering from numerous liver metastases in both lobes from colorectal primary isolated liverperfusion with 5-fluorouracil was performed. By means of a special cannulation system the hepatic artery and the portal vein were arterialized. The patients recovered rapidly after the operation. Sonographic measurements, CAT scans, pulse cytophotometry, and second-look operations with histological examinations of metastatic tissue verified extensive tumor regression. No complications occurred within 6 months after the perfusion treatment.

Animals↗
PubMed1983

Ultrastructural changes in the dog liver cell after isolated liver perfusion with various cytotoxins.

Following isolated liver perfusion with different cytotoxins - 5-fluorouracil (5-FU), methotrexate (MTX), dacarbazine (DTIC) cis-platinum (cis-PT) - liver tissue of dogs was examined with the electron microscope (a) directly after the perfusion and (b) after a survival time of 4 weeks (5-FU and DTIC). Acute disintegration of the granular endoplasmic reticulum and depletion of the glycogen stores occurred after perfusion with 5-FU, MTX, and DTIC, while cis-PT induced disintegration of the granular endoplasmic reticulum accompanied by an accumulation of glycogen. Four weeks after perfusion with DTIC signs of remarkably increased cellular activity were observed, while 4 weeks after perfusion with 5-FU the parenchymal liver cells revealed a well-balanced and moderate recovery of the cellular structures.

Animals↗
PubMed1983

Tissue toxicity in experimental isolated perfusion with adriamycin.

Adriamycin is known as an antineoplastic agent with a broad spectrum of activity for human malignancies. To determine the highest tolerable concentrations of adriamycin in isolated perfusion of the extremities the hind legs of 12 dogs were isolated in an extracorporeal circuit and perfused under normothermic conditions. Dosages of about 10 mg/l perfused extremity were well tolerated by the animals, and lower concentrations did not result in any side effects. However, in most cases, dosages higher than 10 mg adriamycin/l extremity volume induced severe edema, pain, and histological changes.

Animals↗
PubMed1982

[The effect of intermittent hydrogen chloride exposure on the lung function of the guinea pig].

23 guinea pigs were exposed to 15 mg/m3 HCl gas 5 days/week, 2 hours daily, for 7 weeks. 15 animals served as controls. From the 5th day of exposure, the following lung function parameters were evaluated in anaesthetised animals: VT, fR, minute volume, TGV, Vmax, R1, Rw, Rrs, Cl, Cw, Crs, delta Poes/VT, hemoglobin, SaO2, PaO2, PaCO2, pH, SBC, BE. These measurements showed no differences between HCl-exposed animals and controls. Histological examination of the lungs revealed no changes which could be attributed to HCl-exposure. This study relates to the important question whether lung damage can be induced by industrially produced, intermittent high levels of HCl in the environment.

Animals↗
PubMed1982

[Isolated liver perfusion with 5-fluorouracil (5-FU) in the human].

In two patients with liver metastases from colorectal cancer an isolated perfusion of the liver with 5-fluorouracil was performed. The primary tumors had been resected 5 weeks and 11 months before the perfusion treatment. By means of special cannulation system the hepatic artery and the portal vein were both arterialized. The patients recovered well after the operation. Sonographic measurements of the metastases showed colliquation areas in the tumours postoperatively.

Chemotherapy, Cancer, Regional Perfusion↗
PubMed1981

Fever response in the guinea pig before and after parturition.

The febrile response to an intramuscular injection of bacterial endotoxin (E. coli 4 microgram/kg) was tested in guinea pigs at the end of pregnancy in the time period extending from 8 days before until 3 days after parturition. In comparison to non-pregnant female controls both fever height and fever index were reduced in mother guinea pigs one week before parturition. This response was gradually reduced and reached its minimum on the last day before parturition. Immediately after parturition the fever response was still suppressed in mother animals as well as in newborns. Several hours after birth the fever response increased again in both groups of animals. The onset time and duration of fever were, however, shorter than in controls. The full fever responsivity was not reached until several days postpartum. Apparently the guinea pig develops an active antipyresis during the last phase of pregnancy. This resembles the suppression of fever in ewes at term of pregnancy where endogenous arginine-vasopressin has been proposed as an antipyretic agent. The vasopressinergic neuronal systems have therefore been localized by immunohistochemical methods in the brains of the guinea pigs whose responses to bacterial endotoxin were studied. These studies, which are described in detail in a following paper, support the involvement of vasopressin in natural antipyresis in the guinea pig.

Animals↗
PubMed1981

[Discriminating power of multivariate parameters of respiration in epidemiological studies (author's transl)].

Applying a broad scale of lung function tests in epidemiological surveys (929 metal workers of a big industrial shop, 211 of them with signs of chronic obstructive lung disease, COLD, and 1,266 pupils of 2 towns with different dust exposition) we found similar multivariate discriminant functions in all age groups between 7 and 79 years of age to differentiate between COLD-population and normal population. Residual volume in % of total capacity (RV/TC) seems to be the most relevant central parameter in all age groups, which should be combined with one of the inhomogeneity parameters of single breath or multi breath distribution tests ( delta F/ delta V or breath of inhomogeneity IHB) in juveniles between 7 to 16 years of age and with closing volume (CV/VC) in adults between 20 to 79 years of age. Conventional ventilation parameters and the arterial oxygen tension don't contribute additional information to multivariate analysis, which isn't already summarized by the parameters RV/TC.

Adolescent↗
PubMed1981

[Airway-resistance in pregnancy measured by oscillation-technique (author's transl)].

Measurements of resistance were performed in 430 healthy pregnant women, 30 non-pregnant women and 33 puerperae by employing the oscillation-technique. The patients were studied in sitting and standing positions. It was found, that 2 maxima of resistance exist in pregnancy: the first in the 6th, the second in the 9th month. In the sitting position the resistance was higher than in the standing one.

Airway Resistance↗
PubMed1980

Reactivity pattern of vasopressin-containing neurons and its relation to the antipyretic reaction in the pregnant guinea pig.

Changes in the content of vasopressin-immunoreactive material in neurons and their projections were examined in pregnant and nonpregnant guinea pigs as well as in mother and newborn animals. Before sacrifice all animals used in the present study were submitted to a pyrogen test, during which the pregnant animals displayed a reduced fever response to exogenous pyrogen. The unlabeled enzyme-immunoperoxidase method was used in the present study. Light microscopic examination showed that, in comparison to all other groups examined, the pregnant animals exhibited a reduced content of the vasopressin-immunoreactive substance in the supraoptic nucleus (SON), in the neuronal pathways extending between the paraventricular nucleus (PVN) and the SON, as well as in the axons projecting to the neural lobe of the pituitary. An increased amount of vasopressin-immunoreactive material was observed during pregnancy especially in the medial portion of the PVN, in axonal distensions in the external zone of the median eminence and in the extrahypothalamic projection sites of the PVN in the lateral septum and in the amygdala. In the pregnant animals neurovascular contacts of vasopressinergic perikarya and fibers were abundant in the PVN; in the lateral septum and in the amygdala vasopressinergic terminals appeared to contact neurons of other types. It is suggested from the present immunocytochemical results that activation of neurons in the medial portion of the PVN and the increased number of vasopressinergic terminals and preterminals in the lateral septum and in the amygdala might be functionally involved in fever suppression at the term of pregnancy.

Amygdala↗
PubMed1979

[Calculations of airway parameters from expiratory concentration volume values based on the model of stationary bronchoalveolar gas exchange (author's transl)].

Approximating the cumulative cross section of the terminal airway structure by a single parabolic exponential term with the unknown parameters initial cross section a, exponential steepness b and external dead space VDE, calculations of the stationary concentration front F along airway length L, raising during constant flow inspiration, were done, solving the gas transport equation for stationary conditions numerically and integrating the distribution of dF/dL. The conversion to the expiratory F-V profile was done neglecting pulmonary inhomogeneity and expiratory front deformation. Calculations were applied on a scale of different a and b enclosing normal and some pathological lung models. Applying different inspiratory flows, there is a linear correlation between the reciprocal steepness dV/dF of expiratory F-V diagrams and the flow diffusion ratio V/D*, where D* is the effective diffusivity of gases. Compared to normal, the model of nonobstructive emphysema shows higher values of dV/dF and the general obstruction lower ones; all three have the same increase of dV/dF along V/D*. The peripheral obstruction type has the highest slope of regression along V/D* and the obstructive emphysema the lowest one. Mathematical approximations of the regression between dV/dF of the expiratory F-V diagram at certain intervals of F and V/D* were used to present a procedure calculating airway parameters a, b, VDE and the effective diffusivity D* from a sequence of F-V diagrams applying different inspiratory flows.

Airway Obstruction↗
PubMed1978

Control of non-shivering thermogenesis in a hibernator.

Present experiments indicate that in hedgehogs two different control mechanisms of non-shivering thermogenesis (NST) exist. During arousal from hibernation catecholamines control heat production in the interscapular brown adipose tissue. In a non-hibernating state, cold-induced NST is controlled by a desoxycorticosterone-like acting compound. The effector system of this second mode of NST is obviously not the interscapular brown fat but a layer of brown adipose tissue which covers the whole back of the hedgehog.

Animals↗
PubMed1976

Thermosensitivity of preoptic neurones in a hibernator (golden hamster) and a non-hibernator (guinea pig).

Thermosensitivity of preoptic units was studied at hypothalamic temperatures (Thy) ranging from 8-43 degrees C in golden hamsters in a non-hibernating state as well as in guinea pigs. In golden hamsters 2 types of thermoresponsive preoptic neurones were found: 1. Neurones sensitive to Thy ranging from 10-42 degrees C with an exponential characteristic and very high spontaneous firing rates (29-59 imp/s) at Thy 36-37 degrees C. 2. Neurones with a bell-shaped temperature-firing rate characteristic, a negative temperature coefficient at Thy 40-30 degrees C, a maximal activity at Thy 20-30 degrees C and a positive temperature coefficient (+0.8 to +4 imp/s-degrees C) even at Thy close to 10 degees C. In guinea pigs thermoresponsive preoptic units became inactive or insensitive to thermal stimulation as soon as Thy fell below 30 degrees C. These results suggest that in hibernators central nervous structures involved in temperature regulation are adapted to maintain their function over the wide range of core temperatures which occur during the different phases of hibernation.

Animals↗
PubMed1976

[Computer analysis of mechanics of breathing by semi-on-line technique (author's transl)].

A program for the analysis of lung mechanics based on esophageal technique and running on mini-computer Cellatron 8205 is described. There are two varieties of analog-digital-conversion of primary flow- and pressure-signals from magnet tape storage to punch tape input channel using transposition of frequency either with sequential or alternating data collection oriented on respiratory half-cycles and unlimited in view of function test time. The program gives a complete status of lung mechanical parameters per respiratory half-cycle and total-cycle, that is pulmonary compliance, elastance, maximal resistance, minimal resistance, peak flow resistance, initial and terminal standard flow resistance, total, static and dynamic work of breathing, power of breathing. Output is provided both in writing and punching results to establish the connection with sequential high-level programs of lung mechanics and statistical data processing.

Computers↗