Biomedical subjects

R Schuster

Publications and source records attributed to R Schuster.

At least 19 recordsLinked to original sources

PubMed1992

A new simulation approach for the determination of the error of parameters of biological importance describing the growth of the Ehrlich ascites tumor of the mouse.

Some aspects of the growth of the Ehrlich ascites tumor of the mouse can be described by the logistic function. The parameters used are fitted to the experimental data in a nonlinear way. It is important to determine the error of these parameters of biological importance in order to discriminate between different consequences induced by various experimental situations by means of statistics. But often there is a gap between the data that are available and the stronger assumptions necessary for statistics. We propose a simulation approach which also works in a much larger range of similar situations to close this gap.

Animals↗

PubMed1992

Budd-Chiari syndrome as the primary manifestation of a fibrolamellar hepatocellular carcinoma.

An 18-year-old female patient was admitted with ascites, right upper abdominal tenderness and peripheral edema. Angiography showed complete occlusion of the vena cava inferior up to the level of the right atrium. By open heart surgery, masses of thrombotic material were pulled out of the v. cava inferior/vv. iliacae which histologically contained tumor cell populations consistent with a hepatocellular carcinoma. Celiacography showed a highly vascularized tumor in the right hepatic lobe. Histologically, it proved to be fibrolamellar subtype hepatocellular carcinoma.

Adolescent↗

PubMed1992

[The modification of Helicella obvia by Dicrocoelium parthenitae].

During the pasture period in 1990 the snail species Helicella obvia, collected in a dicrocoeliosis area in the east of Brandenburg, was investigated for Dicrocoelium sporocysts. Simultaneously in adult snails the condition of albumen gland was examined. Investigations showed that Dicrocoelium infection in the snail host impairs their reproduction ability and life expectancy. The term "parasite caused sterilisation" is suggested for changes which lead to infertility in the case of parasite infection.

Animals↗

PubMed1991

Minimization of intermediate concentrations as a suggested optimality principle for biochemical networks. II. Time hierarchy, enzymatic rate laws, and erythrocyte metabolism.

The multiobjective problem of minimizing all intermediate concentrations is solved for a model of glycolysis, the pentose monophosphate shunt and the glutathione system in human erythrocytes. It turns out that one solution out of four obtained corresponds qualitatively to the real system. Furthermore, it is shown that for any reaction system, the mentioned optimality principle implies distinct time hierarchy in that some reactions are infinitely fast and subsist in quasi-equilibrium. Finally, the relationships to the standard method of deriving enzymatic rate laws are discussed.

Energy Metabolism↗

PubMed1991

Radiotherapy and breast reconstruction: clinical results and dosimetry.

Immediate or delayed reconstruction using implants or autologous tissue transfer is increasingly offered to women undergoing mastectomy for breast cancer. Some patients require radiotherapy for prevention of local/regional relapse, and some for post-surgical local/regional recurrence. Others with augmented breasts may opt for conservative surgery and irradiation. At Washington University, 70 breast cancers were irradiated in 66 patients following mastectomy with reconstruction (N = 61) or wide local excision of an augmented breast (N = 5). Two patients elected to have a second reconstruction after an unsatisfactory initial result. Thus, 72 breasts were evaluated after radiotherapy for tumor control, complications, cosmesis, and patient satisfaction. Locoregional failure occurred in only five patients, one following adjuvant radiotherapy after mastectomy with reconstruction and four following radiotherapy for recurrent breast cancer within a reconstructed breast. Grade 2 or 3 complications occurred in 34 patients (51%). The complication rate was highest in autologous tissue transfer reconstructions. Cosmetic results were evaluated good/excellent in 49% by physicians and 67% by patients. Immediate reconstructions had fewer good/excellent physician evaluations (32%) compared with reconstructions performed at least 6 weeks after radiotherapy (55%). Transverse rectus abdominis flaps had the best cosmesis scores, followed by permanent silicone prostheses, tissue expanders, latissimus dorsi, and gluteal flaps. Only 48% of patients would choose to have the same reconstructive procedure again. Phantom interface dosimetry with a parallel plate chamber and TLD measurements was performed. Radiotherapy and reconstruction are not incompatible, but careful consideration of their relative timing and technique appear to be important in optimizing cosmesis while minimizing complications.

Adult↗

PubMed1991

Factors influencing the metacercarial intensity in ants and the size of Dicrocoelium dendriticum metacercarial cysts.

During the 1990 grazing season, ants found attached to plants were collected from sheep pastures at monthly intervals and examined for Dicrocoelium metacercariae. The species Formica pratensis and F. rufibarbis showed average metacercarial intensities of 76 and 38 respectively. In addition to the ant species, the intensity of infection was found to be dependent on the length of the ant. The volume of metacercarial cysts was influenced by the intensity per ant relative to ant length but not by the ant species or the time of ant collection.

Animals↗

PubMed1991

[Morphometric analysis of an Anoplocephala perfoliata population].

An Anoplocephala perfoliata population isolated from the caecum of a dead horse was analysed morphometrically. Besides the number of segments, length and width of strobila, the width of scolex and the last segment, in adult tapeworms the number of eggs per segment was counted. By the aid of these data the population was divided into 4 categories. The length of fixed tapeworms varied between 5.46 and 41.53 mm. There was an direct relation between length of the strobila and number of segments. Only 42 of 440 investigated tapeworms contained mature eggs in the uterus. The number of eggs varied between 125 and 4482. The beetle mite Scheloribates latipes could be infected successfully, 9 cysticercoids were isolated from their body cavity.

Animals↗

PubMed1991

[The significance of the flow-volume curve in pediatric lung diseases].

Even slight obstructions in small airways are detectable by means of the flow-volume curve. Therefore this method is to recommend for early diagnosis and especially in infancy. Advantages were demonstrable at the examination of different groups of asthmatics and in children with cystic fibrosis. The great sensitivity of the flow values was also shown at the bronchospasmolytic test and for provocation tests particularly. The flow-volume curve is an important routine method in pediatric pulmonology to determine the dimension and location of ventilation disorders and for follow-up studies and therapy supervision.

Airway Resistance↗

PubMed1991

[Automobile driving studies to determine alcohol-induced driving insecurity after dark].

To further elucidate the question whether the criteria for assessing alcohol-induced unfitness to drive should be stricter for night-time than for day-time driving (cf. Schewe et al., 1977) 64 test persons performed automobile driving tests in daylight and in darkness while being sober and while under the influence of alcohol. The first set of tests was done in daylight. A test course of approx. 600 m involving six everyday driving maneuvers had to be covered, first in the sober state and then at blood alcohol concentrations (BAC) of 1.1 g % and 1.4 g %. The driving tests in the dark were performed on the same test course, first in the sober state and then at a BAC of 1.1 g%. In both test series the errors were counted and the driving times measured. Statistical evaluation of the test results was done parametrically (t-test for dependent random samples) and distribution-free (Wilcoxon's test for paired comparison). In the sober state 2.1 errors were made on average during the day and 3.2 errors, i.e. one error more, at night. At 1.1 g %, 4.3 errors occurred during the day but 8.0 errors at night (i.e. 3.7 errors more than during the day). The differences were statistically significant. With 8 errors during night-time driving at 1.1 g % the number of errors was still higher than the average number of 6.8 errors made during day-time driving at 1.4 g %. The average driving times required in the sober state were 241 s during the day and 256 s at night. At 1.1 g %, 243 s were needed during the day and 272 s at night, i.e. on average 17 s more than for day-time driving at 1.4 g % for which 255 s were needed. For an orienting comparison of driving performance it can be assumed that "performance" in the sense meant here is reciprocally proportional to the number of errors and reciprocally proportional to the time required, i.e. on the whole reciprocally proportional to the product from number of errors and time. The deterioration of performance can be illustrated best by assuming performance in the sober state during the day to be 100% and relating the other "performances" thereto.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

Cystic neoplasms of the pancreas: a clinical and radiological study of eight cases.

Four patients with benign serous cystadenoma, one with mucinous cystadenoma, and three with mucinous cystadenocarcinoma treated in the university hospital of Göttingen between 1985 and 1988 were investigated. The main initial symptoms of these cystic tumors were abdominal pain (7/8), weight loss (3/8), maldigestion (3/8), and palpable abdominal mass (3/8), while laboratory investigations revealed nonspecific alterations (elevated ESR, mild hypochromic anemia). CA 19-9 was elevated in two patients, one of whom had cystadenocarcinoma; CEA also was elevated in this patient only. In all cases size, localization, and cystic character of the tumors were shown clearly by sonography and computed tomography; fine needle biopsy helped to distinguish between serous and mucinous cystadenoma in four of six cases. Because of their malignant potential, total extirpation of mucinous cystic tumors is the treatment of choice, while serous cystadenomas are benign and therefore may be treated conservatively in uncomplicated cases or high-risk patients.

Adult↗

PubMed1990

Prenatal development of mesencephalic and diencephalic dopaminergic systems in the male and female rat.

Previous results had suggested mesencephalic dopaminergic neurons in cultures of gestational day (GD) 14 rat embryonic brains to be characterized by an early maturation and acquisition of sex-related differences in transmitter uptake. Therefore development of dopaminergic systems was reexamined in the rat in vivo with special emphasis on the prenatal period, mesencephalo-hypothalamic relationships, and possible sex differences. Perfusion-fixed brains of GD 14, 17, 20, 21 and newborn rats were sectioned or processed as whole-mounts and immunostained for tyrosine hydroxylase (TH). Total numbers of mesencephalic TH-immunoreactive cell bodies as assessed by a stereological method rose between GD 14 and 17 and fell again between GD 17 and 21. As early as GD 14, a prominent mesencephalo-hypothalamic projection was observed coming off the medial forebrain bundle and terminating in the retrochiasmatic region. Two additional TH-immunoreactive fiber bundles leaving the medial forebrain bundle, one rostral and one caudal to the former, and terminating in the paraventricular and premammillary region, respectively, were noticed on GD 17. Careful examination of developing TH-immunoreactive neurons in the lower brainstem ascertained that there was no interference from ascending catecholaminergic fibers other than dopaminergic of mesencephalic origin during this early prenatal period. All 3 mesencephalo-hypothalamic projections had largely disappeared by GD 20 and were no longer detectable as distinct fiber bundles thereafter. There were subtle sex differences in numbers and distribution of both mesencephalic and diencephalic TH-immunoreactive neurons present at GD 17, which thus occurred prior to manifestation of other well-known sexual dimorphisms of the rat brain.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Mathematical modelling of metabolic pathways affected by an enzyme deficiency.

The regulation of metabolic pathways of the red cell affected by an enzyme deficiency is studied on the basis of comprehensive mathematical models. The main steps of such a theoretical approach are outlined considering individual alterations in the kinetic properties of two regulatory enzymes: pyruvate kinase and glucose-6-phosphate dehydrogenase. It is demonstrated that mathematical modelling helps to relate the observed changes of cellular quantities as shortened life-span, or as resistance against oxidative stress to alterations in the metabolic regulation.

Animals↗

PubMed1990

Hormonal and renal responses to arterial chemoreceptor stimulation by almitrine in healthy and normotensive men.

Healthy and normotensive men (n = 11) were hospitalized and kept under controlled fluid and sodium intake (120 mequ/d) for 5 days. Their systemic arterial blood pressures as well as heart and breathing rates were measured, and venous blood and urine samples were collected at intervals of 1-4 h. Diuresis was induced by scheduled drinking of tea (150 ml/h). Electrolytes, osmolality, and creatinine were determined in both plasma and urine samples. Aldosterone, cortisol, and vasopressin concentrations were measured only in the plasma. On the 2nd and 3rd day of the experiments the participants received orally either a placebo-pill or 100 mg almitrine bismesylate (Vectarion). Each subject was tested in a placebo- and an almitrine experiment. The subjects responded to the almitrine treatment with a suppression of the plasma aldosterone content, a transient rise of glomerular filtration rate, a natriuresis and an increase of renal concentrating ability. In the placebo-experiments, only the transient rise of filtration rate was significant. The data indicate that almitrine, by stimulating the peripheral arterial chemoreceptors, suppresses plasma aldosterone and inhibits renal proximal sodium reabsorption by so far unknown mechanisms. They also suggest that oral and intravenous almitrine administrations, respectively, might differently affect renal hemodynamics and excretory function.

Adult↗

PubMed1990

[Hot air coagulator for the treatment of bleeding of parenchymal organs].

Experiences are described about the hemostasis in parenchymatous organs by means of a self-constructed hot air coagulator. Bleedings in liver, spleen, and kidney were caused experimentally in 15 dogs. A certain control of hemorrhage were carried out by hot air. The own hot air coagulator was superior to other coagulators by the little weight and the fast and noiseless working.

Air↗

PubMed1990

Influence of sorbitol and mannitol on the reactions of kidney excretory function evoked by arterial chemoreceptor stimulation with almitrine in anaesthetized and artificially ventilated cats.

The reactions of renal hemodynamics, as well as of excretory and concentrating function (clearance-technique) in response to arterial chemoreceptor stimulation by almitrine bismesylate were studied in 3 groups of chloralosed, relaxed, and constantly ventilated cats. In 2 groups of chemoreceptor-intact animals an osmotic diuresis was induced by intravenous infusion of an isoionic solution containing equivalent amounts of either sorbitol or mannitol. Under similar conditions the 3rd series of experiments was carried out in cats under mannitol diuresis but with deafferented arterial chemoreceptors. The changes of mean arterial and central venous pressures as well as of the parameters of the arterial acid-base balance were similar in all groups of cats studied. The chemoreceptor-intact animals undergoing sorbitol diuresis did not show any natriuresis in response to the drug but reacted with a remarkable increase in their U/Posm and TCH2O/Cosm ratios. In contrast, the chemoreceptor-intact animals infused with mannitol in saline reacted to almitrine with a transient natriuresis but with only a weak increase in their U/Posm and TCH2O/Cosm ratios. The data suggest that arterial chemoreceptor stimulation inhibits proximal tubular sodium reabsorption. In the sorbitol-experiments during chemoreceptor stimulation the enhanced delivery of sodium by the proximal fluid was reabsorbed in the thick ascending limb of Henle's loop thus increasing medullary osmolality and renal concentrating ability. Mannitol apparently limited this additional sodium reabsorption in the thick ascending limb of Henle's loop; therefore in the mannitol-experiments during chemoreceptor stimulation a natriuresis but only relatively weak changes of renal concentrating function occurred. The data also suggest that a pharmacological chemoreceptor stimulation might support the recovery of renal excretory function post-anaesthetically, although the optimal solution infused to induce an osmotic diuresis remains to be determined.

Almitrine↗

PubMed1990

[Statistical study of alcohol intoxicated female victims of sex offenses].

Comparing 133 presumable rape victims who underwent blood sampling after the event with 2446 alcoholized female traffic offenders it was found that both groups had a delinquency maximum between midnight and 2 a. m. and a delinquency minimum between 6 a. m. and 6 p. m. Most of the rape victims, however, were approximately 5 years younger than the traffic offenders, most of whom were about 25 years old. The time intervals between blood sampling and the event were longer in the case of the rape victims (4 to 20 hours) whereas most traffic offenders underwent blood sampling 1 to 2 hours after the event. At comparable maxima of the distribution curves of blood alcohol concentration (between 1.5% and 2%) that of the rape victims showed a shift to higher values. This is also illustrated by the mean values of blood alcohol concentration at the time of the event: the blood alcohol concentration of the rape victims was 2.24% and thus 0.45% higher than that of the traffic offenders, who averaged only 1.97%. The reason for this is probably to be seen in the different modes of back computation. By assigning 38 offenders to 35 victims it was possible to set up and compare 35 pairs. Comparing the blood alcohol concentrations of all 35 pairs it was found that the blood of the victims contained on average 0.4% more ethanol than the blood of the offenders (1.41% vs. 1.01%).

Accidents, Traffic↗

PubMed1990

[Driving fitness of female headache patients in tests of traffic medicine--a psychotechnical investigation].

To detect differences in psychophysical performance during pain attacks and pain-free intervals, 30 female patients aged 21 to 58 years and suffering from attacks of headache were investigated intraindividually by means of established test methods (attention quotient according to Grüner, motorial accomplishment series according to Schoppe and achievement testing device). The patients were randomized and assigned either to Group A (first test while having pain) or Group B (first test without pain). The patients were also asked to assess the intensity of their headaches. The hypothesis that "headaches do not impair psychophysical performance" was refuted by the significant results obtained in all tests, the observed deficits concerned predominantly achievements in the field of concentration, achievements which are also required for operating a motor vehicle.

Adult↗

PubMed1990

[Initial experiences with "Oranienburg" slow-release theophylline in asthma therapy of children and adolescents].

Experiences in 50 patients show that Theophyllin retard Oranienburg (280 mg theophylline) could be used as an effective bronchospasmolytic drug on conditions of mono- and combination-therapy. Advantages of this preparation are improvement of the compliance and an undisturbed night-sleep in patients. However an optimum dosage is hardly maintained in children by the present dose of a single tablet of 280 theophylline content. The effectiveness in therapy of childhood asthma could be improved by stronger sustained release effect and different doses of tablets.

Adolescent↗