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Biomedical subjects

G Fischer

Publications and source records attributed to G Fischer.

At least 433 records · Page 24Linked to original sources
PubMed1987

Decrease in glucokinase and glucose-6-phosphatase and increase in hexokinase in putative preneoplastic lesions of rat liver.

Preneoplastic liver lesions were produced in female Wistar rats by oral administration of 2-acetylaminofluorene for 165 days succeeded by a carcinogen-free standard diet up to 420 days. During the treatment numerous altered hepatic foci (AHF) and hyperplastic nodules (HN) were detected histochemically by a focal decrease or lack of adenosine-5-triphosphatase and glucose-6-phosphatase (G-6-Pase) activities. In addition, the immunohistochemically demonstrable amount of L-type pyruvate kinase was clearly reduced. The histochemically demonstrated decrease of G-6-Pase was substantiated by microbiochemical determination of the enzyme activity in microdissected material. Moreover, during the experimental period a continuous decrease in glucokinase and an increase in hexokinase was detected microbiochemically within AHF and HN. These alterations indicate a shift in the carbohydrate metabolism from gluconeogenesis to glucose utilization and pentose-phosphate-pathway for biosynthesis of nucleic acids. Beside other oncofetal markers, HK may be used as indicator of the early stages of liver carcinogenesis.

2-Acetylaminofluorene↗
PubMed1987

Immunohistochemical demonstration of decreased L-pyruvate kinase in enzyme altered rat liver lesions produced by different carcinogens.

Preneoplastic liver lesions were produced in female Wistar rats by application of 25 mg/kg N-nitrosomorpholine (NNM), 14 mg/kg diethylnitrosamine (DENA), 0.075 mg/kg aflatoxin B1 (AFB1) or 160 mg/kg safrole. These carcinogens were administered in two equal doses 12 and 24 h after partial hepatectomy. The animals then received sodium phenobarbital (0.1% in tap water) for up to 410 days. Numerous altered hepatic foci (AHF) and hyperplastic nodules (HN) were detected enzyme histochemically by their negative ATPase reaction after application of AFB1, DENA and NNM; some AHF and HN were also caused by the weak carcinogen safrole. Immunohistochemically these lesions were also L-pyruvate kinase (L-PK)-negative with a high coincidence with regard to their number and area. These results confirm the role of L-PK, an enzyme affecting the pentose phosphate pathway, as a negative marker of preneoplastic liver lesions.

Animals↗
PubMed1987

[Further findings on the mesencephalic veins].

On 50 human brains the width and course of the veins on the surface of the mesencephalon were determined. The basal vein, for example, has an inside diameter of 1.70 (0.91-2.88) mm. A lateral mesencephalic vein could be demonstrated in 70% of the cases, the width being 0.81 (0.29-1.78) mm. A posterior mesencephalic vein was found in 51%, measuring 0.57 (0.24-1.01) mm in diameter. The ponto-mesencephalic vein and the intercollicular vein were also included in this examination.

Cerebral Veins↗
PubMed1987

[Further findings on the diencephalic artery branches].

Following earlier examinations, we determined the number, extracerebral length and pattern of branching of the diencephalic branches in 50 human brains. These small arteries have their origin in the anterior cerebral artery, the anterior communicating artery, the posterior communicating artery, the anterior choroidal artery, the posterior cerebral artery, the basilar artery and the superior cerebellar artery. With regard to the number and width of these vessels, we found some minor differences compared with specimens examined earlier. The extracerebral length and branching inside the skull have not so far been examined by us.

Arteries↗
PubMed1987

Antihypertensive effects of niguldipine-HCl (B 844-39), a new calcium antagonist in dogs.

B 844-39 is a new dihydropyridine calcium antagonist with a long-lasting antihypertensive action. Preliminary tests in chronically instrumented normotensive dogs revealed that B 844-39 (0.3 mg/kg p.o.) caused a marked decrease in blood pressure which was accompanied by a counterregulatory increase in heart rate. Both effects outlasted the 6-h observation period. There was no sign of cardiac depression in left ventricular positive dP/dtmax or sonomicrometrically evaluated subendocardial systolic shortening. B 844-39 was also tested in renal hypertensive dogs over a period of 12 days to investigate its potential in the long-term treatment of hypertension. A dosage of 0.3 mg/kg given orally twice a day led to a marked and persistent decrease in blood pressure, which was accompanied by a positive chronotropic effect and increases in plasma renin activity and angiotensin II. This initial counterregulatory response was blunted within several days of chronic treatment. After completion of the 12-day treatment period, the blood pressure reduction persisted for greater than 14 days. B 844-39 induced a marked and persistent reduction in blood pressure in hypertensive dogs, even with prolongation of the dosing interval to 24 h. The hypotensive effect of this drug was more pronounced in hypertensive than in normotensive animals.

Animals↗
PubMed1987

Stepwise degradation of the hexapeptide Met-Ala-Ser-Pro-Phe-Ala by dipeptidyl peptidase IV.

Dipeptidyl peptidase IV (dipeptidyl-peptide hydrolase, EC 3.4.14.-) purified from pig kidney was proved to split off the N-terminal dipeptide Met1-Ala2 and, subsequently the dipeptide Ser3-Pro4 from the synthetic model peptide Met-Ala-Ser-Pro-Phe-Ala representing the N-terminal part of a signal sequence of leucocyte interferon. The kinetic parameters for the release of Met1-Ala2 (Km 3.2.10(-5) mol.l-1 and Ser3-Pro4 (Km 1.65.10(-4) mol.l-1, kcat57.9 s-1) were determined. The dipeptides Ser-Pro and Phe-Ala were found to be competitive inhibitors of the hydrolysis of Gly-Pro-NHNp by dipeptidyl peptidase IV.

Animals↗
PubMed1987

[Pilot study of the nitrate, nitrite and bacterial content of human saliva as a function of environmental factors].

In a random sample comprising 160 test persons nitrate (12.4 +/- 7.6 mg/l) and nitrite (5.7 +/- 4.0 mg/l) concentrations as well as bacteria counts in saliva were determined. No dependence of the values from age and sex could be detected, whereas smokers have lower concentrations of both nitrate and nitrite. Persons suffering from inflammatory diseases did not have enhanced nitrate concentrations. Role of bacteria for nitrite production is confirmed. Patients, regularly taking nitro-remedies, showed enhanced NO3--(25.8 mg/l) and NO2--(8.4 mg/l)-values.

Adult↗
PubMed1987

[Bioenergetics].

As introduced previously, the information field can serve as a base for inferences in terms of dynamics but also of relativity, with the latter being discussed regarding the possibility of transformation between information and energy (and mass as well). An energy equivalent of information is obtained: b, a new constant of nature, patterned after the mechanical equivalent of heat. Some approaches to the calculation of b are considered. Proceeding from the laws of transformation, a more general rule of information conservation is obtained, which may also be written as an equation of matter. The transformations can be presented also by geometrical means. In the m-W-I model space, all biological processes seem to be functions of time. By letting time be x4 = ict with a view to the spatial coordinates of the model space, the Minkowski space is shown to apply to biology too, where it seems to have implications similar to those it has in physics. In 2 tables, a systematic listing of origins and results of biodynamics and bioenergetics (biorelativity) is given.

Energy Metabolism↗
PubMed1987

[Complete excision of acoustic neurinoma. Preservation of the facial nerve and hearing].

Using microtechniques, total removal of acoustic neuromas with facial nerve preservation is possible today in most cases. The next barrier of operative treatment is hearing preservation which is routinely attempted, with the help of intraoperative brainstem auditory evoked responses monitoring. The present series deals with 176 operations performed sub-occipitally in 159 patients from 1970 up to 1985. Twelve patients were operated upon 29 times. According to the W.T. Koos classification, there were 16 type II, 39 type III and 121 type IV neuromas. Ten patients died postoperatively. In seven of these, death was related to surgery, in two it was caused by respiratory failure. In the last patient unexplained sudden death occurred. 169 patients had no facial weakness preoperatively, in 158 of these the facial nerve was anatomically preserved (93.5%). Facial nerve function was judged by evaluation of function of face at least 12 months after operation. Up to 36 months after surgery, a good facial result may be expected in cases where the facial nerve was macroscopically spared at completion of removal. Functional results have been reviewed in 151 patients according to the J.W. House's International Evaluation System, with an excellent or good result in 66 (44%), fair in 65 (43%), bad or poor in 20 (13%). The anatomical preservation of the cochlear nerve could be achieved in 80 patients of the group of 169 in whom the auditory function had not been damaged by a previous operation. In fact, the auditory function preservation could be reasonably attempted in 79 patients: showing a hearing loss below 70 dB on tone audiometry, whatever may be the result of speech discrimination score. 59 patients (75%) of this later group had their auditory nerve preserved, 14 (18%) showed preserved hearing function postoperatively, 10 of these with a speech discrimination score over 50%. Two of these showed an improvement of preoperative hearing, two others showed a total recovery of hearing function after removal.

Adolescent↗
PubMed1987

[Intracranial pneumocephalus under pressure. A possible cause of postoperative deterioration in neurosurgery. 10 cases].

10 patients in whom an early post operative alteration of the level of consciousness or of the neurological status could be related to a tension pneumocephalus are reviewed. Four underwent a surgical procedure in the sitting position. Among these, 2 had been previously shunted for hydrocephalus. A 5th patient underwent a IIId ventriculocisternostomy for tumorous occlusion of the aqueduct. The other five patients were involved with supra-tentorial conditions (hemispheric glioma: 1 case, meningioma: 1 case, chronic subdural hematoma: 3 cases). The post-operative deterioration clinically suggested a post operative hematoma. CT showed a very low density effusion either located in the operative area or in the subdural space or both, with significant mass effect. 9 patients steadily improved after conservative therapy. In 1 case, reoperation was required. Pathogenesis of symptomatic pneumocephalus remains controversial. The role of the sitting position and of CSF drainage seem likely. Spontaneous or nitrous oxide induced expansion of post-operative residual intra cranial air plays a debatable role. It is postulated that tension pneumocephalus may result from a discrepancy between spontaneous reexpansion of the cerebral mass and a residual air collection. Such complications are regarded as serious enough to justify several preventive measures.

Adult↗
PubMed1987

[Lumboperitoneal shunt in persistent or recurrent fistulae of the base of skull. Apropos of 20 cases].

The authors describe the use of the lumbo peritoneal shunt (L.P.S.) in 20 cases of C.S.F. rhinorrhea following either cranial injury [13] basal skull surgery [2] or of unknown etiology [5]. 16 patients had previously undergone an attempt at direct closure of their fistula and are therefore cases in which the direct approach failed. 4 patients underwent the L.P.S. straightaway. In 17 cases the fistula was healed by the L.P.S. without any recurrence, though a shunt removal was necessary in 5 cases. The method was unsuccessful in only 3 cases.

Adult↗
PubMed1987

Prevention of stress-induced damage in experimental animals and livestock by monomagnesium-L-aspartate hydrochloride.

Monomagnesium-L-aspartate hydrochloride (Mg-Asp. HCl) is readily absorbed from the intestine of rats because this process is not saturable. Depending upon the dose administered, Mg-Asp. HCl exhibits Ca-antagonistic effects and inhibits the release of stress hormones. Higher concentrations of Mg salts, which do not contain chloride, e.g. MgO, tend to induce hypochloremic, metabolic alkalosis and changes of urinary pH, whereas MgCl2 produces hyperchloremic acidosis under these conditions. Evidence is given that oral supplementation with Mg-Asp. HCl has beneficial effects not only in experimental animals or livestock, but also in man, e.g. on exposure to muscular stress.

Acid-Base Equilibrium↗
PubMed1986

Phospholipid distribution in the microenvironment of the immunoglobulin E-receptor from rat basophilic leukemia cell membrane.

It has been previously found that lipids were required to maintain intact the tetrameric structure of the receptor for immunoglobulin E (IgE) (Fc epsilon R) in detergent solutions [Rivnay, B., Rossi, G., Henkart, M., & Metzger, H. (1984) J. Biol. Chem. 259, 1212-1217, and references cited therein]. Failure of commercially obtained lipids to provide sufficient protection, however, underscored the necessity for development of additional analytical approaches. In order to identify the phospholipid distribution in the intimate natural environment of this receptor, both the plasma membrane vesicles and the ligand-receptor complex (IgE-Fc epsilon R) have been isolated by affinity chromatography. The phospholipids of both preparations were compared. After extensive washing with detergent lipid micelles, IgE-Fc epsilon R retained 0.1-1% of the total phospholipids in the purified plasma membrane. The receptor-bound lipids were shown to contain phosphatidylcholine and sphingomyelin; the content of the latter lipid was enriched 2-5-fold compared with that in the plasma membranes. This pattern was observed with several detergents employed for purification and under a variety of experimental conditions. In light of the general distribution of choline phospholipids in the outer leaflet of plasma membranes, this enrichment may not be a characteristic of this particular receptor exclusively. These observations should be particularly helpful in studies on aggregation-induced functions of the isolated Fc epsilon receptor. In general, the methods employed enable isolation of purified and lipid-protected integral proteins and also provide an appropriate reference source of intact membrane vesicles. These qualities render this approach useful in similar studies of other membrane proteins.

Animals↗