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Biomedical subjects

G Meyer

Publications and source records attributed to G Meyer.

At least 415 records · Page 23Linked to original sources
PubMed1983

Bicarbonate effects, electromotive forces and potassium effluxes in rabbit and guinea-pig gall-bladder.

The stimulating effect of external HCO3- on Na+ salt transport has been examined in rabbit and guinea-pig gall-bladder by electrophysiological methods, as a sequel to a previous study carried out by radiochemical techniques. At steady state, cell K+ activity was found to be significantly reduced in the presence of HCO3-, whereas cell Na+ activity significantly increased; in parallel the apical membrane p.d. was depolarized; K+ equilibrium potential was higher than membrane p.d. in every case. The apical p.d. dependence on K+ was unaffected by HCO3-, but in the guinea-pig it was affected by Cl-. Rapid increases in HCO3- concentration on the luminal side caused a depolarization of the apical p.d. of the guinea-pig within about 30 sec, an effect that did not occur if the tissue was pre-treated with 10(-4) M-acetazolamide; the epithelial resistance and apical/basolateral resistance ratio were unchanged in all cases. The primary action of HCO3- is confirmed to be on the apical membrane; an HCO3- conductance does not seem to be present at this level, either in the rabbit or guinea-pig, nor does HCO3- affect Na+ influx through the apical conductive pathway, so that all the stimulating effects of the anion are confirmed to be on the neutral transports of Na+ salts; in spite of this, the apical electromotive force is modified due to the changed cell K+ activity. The rapid depolarization caused by the anion in the guinea-pig is in agreement with an HCO3- electrogenic secretion and/or a basolateral conductance for the anion. Polyelectrolyte dissociation from protons increases in the absence of external HCO3-: the negative charges are mainly counterbalanced by bound Na+ in the rabbit and by free K+ in the guinea-pig. K+ leakage from the cell into the lumen is calculated to be minimal in the rabbit and all K+ lost could be reabsorbed through the paracellular pathways; K+ efflux to the subepithelial layer via conductive routes is insufficient to account for the over-all K+ efflux.

Animals↗
PubMed1983

Characterization of tumor-specific transplantation antigen induced in cells infected or transformed by polyomavirus.

Tumor-specific transplantation antigen (TSTA) activity was investigated (with the use of inbred BALB/c and C3H mice and inbred Fisher and Wistar rats) in various early polyomavirus (Py)-coded proteins by three methodologies: 1) immunoprecipitation by anti-T-antigen sera, gel slicing, and immunization; 2) affinity chromatography with the use of anti-tumor-associated antigen serum; and 3) use of a Py mutant, NG18. The results obtained by all three techniques allowed refutation of the hypothesis that the three major species of T-antigen possess the main TSTA activity, particularly middle-sized T-antigen which is a plasma membrane protein. TSTA activity was found to be associated with proteins having a molecular weight of approximately 37,000. The exact origin of this protein is discussed.

Animals↗
PubMed1983

Development of the subcommissural organ in the albino mouse (a Golgi study).

The Subcommissural organ (SCO) of the albino mouse has been examined using the Golgi method and stained paraffin sections from embryonic age E 11 up to adulthood. The SCO cells can first be distinguished from adjacent structures at E 14, but are not fully differentiated until the age of 6 postnatal weeks. The first signs of cytological maturation occur during early postnatal life with a progressive invagination of the nuclear membrane and a transformation of the peripheral processes, which involute or are lost in adulthood. The hypendyma appears at the age of three weeks. A third type of cell is described which is interpreted as a transitional element between ependymal and hypendymal SCO cells. In general, the mouse SCO is characterized by an early appearance in prenatal life and a late acquisition of the final differentiated state.

Animals↗
PubMed1983

[Psychiatric consultation service in a large medical clinic: evaluation over a 3-year period].

The report is based on 1,165 medical inpatients seen by the consultant psychiatrist within a 3-year period. During the last year evaluated for this study psychiatric consultation was requested for 2.8% of the total non-psychiatric hospital admissions. Questions to the consultant are most often referred to psychogenic factors, depression and suicidality. The most frequent psychiatric diagnosis was neuroses/reactions/ personality disorders followed by suicidality, organic psychoses, psychosomatic illnesses, endogenous psychoses, somatopsychic syndromes and addictions. Further details and problems in psychiatric consultation are discussed.

Depressive Disorder↗
PubMed1982

Membrane potentials of differentiating enterocytes.

A positional analysis of enterocyte membrane potential has been carried out using in vitro preparations of rabbit distal ileum. Young enterocytes were found to possess a microvillar membrane potential significantly less than that seen in older enterocytes. The length of enterocyte microvilli was also found to be significantly less in younger enterocytes. It is suggested that developmental changes in membrane potential, occurring during the early stages of enterocyte differentiation, probably reflect a changed permeability to ions associated with the establishment of a fully developed microvillar membrane. Other explanations for the observed findings are also considered.

Age Factors↗
PubMed1982

[Incidence, prognosis and prevention of septicaemias in patients under treatment for acute leukaemia (author's transl)].

Septicaemias are frequent and severe in patients with acute leukaemia under aplastic treatment. The present study concerns 69 such patients: 29 with acute lymphoblastic leukaemia (ALL), and 40 with acute non-lymphoblastic leukaemia (ANLL). All were treated in single rooms in the same hospital and in similar conditions. The overall incidence of septicaemia was 62%; it was 60% in patients with recently diagnosed ALL and 68% during relapses. More than 34% of ALL patients and 82.5% of ANLL patients had one or several episodes of septicaemia. Among the 74 pathogens isolated 50% were Gram-positive organisms, 45% Gram-negative organisms and 5% Candida spp.. The first episodes of septicaemias were predominantly caused by Gram-positive spp. (61%) and the subsequent ones by Gram-negative spp. (60%). The primary infection could only be diagnosed in 19% of the cases and was most frequently located in the digestive tract or perineal region. The most common focal complications were lung infections (18 cases), skin infections (12 cases) and septic shock (15 cases). Seventy-four p. cent of the patients survived with prompt and potent antibiotic therapy. Death occurred in 26% and was clearly related to the following factors: chemotherapy of relapsed leukaemia and/or blastic aplasia and/or successive episodes of septicaemia. The incidence and severity of septicaemias in leukaemic patients will only be reduced by improved prophylactic measures against infection and by less pronounced and shorter chemotherapy-induced granulocytopenia.

Acute Disease↗
PubMed1982

Short-axon neurons with two axon-like processes in the visual cortex of the cat. A Golgi study.

In the visual cortex (areas 17, 18 and 19) of adult cats and a 40-day-old kitten, short-axon cells with two axon-like processes are described. These neurons belong to different cell types (spineless stellates of layers II/III and IV, fusiform cells of layers III, IV and V, and a large multipolar spineless cell of layer III). The axon-like processes present the same morphological characteristics as single axons of the corresponding neuronal type.

Animals↗
PubMed1982

Follow-up results from a randomized trial for T3 and T4 breast cancer patients: previous BCG immunotherapy improves response to chemotherapy in the relapse patient.

Following locoregional treatment, patients were randomized into three groups: The first groups received no complementary treatment; the second group received adjuvant chemotherapy (vincristine, cyclophosphamide, and 5-fluorouracil once a month for 12 months); and the third group was treated by immunotherapy (150 mg BCG once a week for 1 year). Sixty-two of the 82 patients studied were menopausal. No significant difference was observed between the three groups. All patients were followed-up for at least 18 months. The disease-free interval difference between the chemotherapy group and the control and immunotherapy groups is not significant. But it should be noted that only 21.8% of the control group did not relapse compared to 57% in the chemotherapy group. BCG immunotherapy in such patients must be considered ineffective. However, our results suggest that patients first treated with BCG respond better to chemotherapy than patients not receiving any previous therapy.

Breast Neoplasms↗
PubMed1982

Maintenance chemoimmunotherapy of nonlymphoblastic acute leukemias.

A trial of maintenance chemotherapy of nonlymphoblastic acute leukemia led to a comparison of two groups of patients in complete remission. Group 1 (14 patients) received only monthly reinduction chemotherapy. Group 2 (17 patients) received identical chemotherapy together with weekly immunotherapy combining BCG and irradiated leukemic cells. While the duration of the first complete remission was unmodified, the overall survival time and, above all, survival after the first relapse were prolonged in group 2 chemoimmunotherapy. These results were all the more marked when a homogeneous group of patients having received the same induction chemotherapy were considered.

Adolescent↗
PubMed1982

Chemodectoma involving the cavernous sinus and semilunar ganglion.

This paper reports a case of paraganglioma involving the cavernous sinus and semilunar ganglion. The origin of the tumor cells, from paraganglia in this region, is also discussed. Recognition of paraganglia in this area may aid the clinician and pathologist in the differential diagnosis of tumors in this region.

Aged↗
PubMed1982

Amiloride-sensitive sodium channels in rabbit and guinea-pig gall-bladder.

1. The effects of low amiloride concentrations (less than 2.5 x 10(-5) M) on the apical membrane (Vm) and transepithelial (Vms) potential differences, transepithelial resistance (Rep) and apical/basolateral membrane resistance ratio (Rm/Rs) have been determined in the gall-bladders of the rabbit and guinea-pig. 2. Vm was hyperpolarized, Vms decreased towards negative values, Rm/Rs increased, but Rep remained unchanged. 3. K+ selectivity of the apical membrane was also checked by increasing luminal K+ concentration from 5.9 to 29.4 mM; the corresponding change in the apical electromotive force was much higher in the rabbit than in the guinea-pig. 4. Pre-incubations with Cl--and HCO3--free salines did not modify K+ selectivity in the rabbit, but nearly doubled it in the guinea-pig. 5. Pre-incubations with control solutions containing 10(-5) M-amiloride in the lumen converted the apical membrane of rabbit gall-bladder into a perfectly K+-perm-selective membrane; the same results were obtained in the guinea-pig only on bathing the tissue with Cl-- and HCO3--free salines together with 10(-5) M-amiloride. 6. It is suggested that in the apical membrane of rabbit gall-bladder K+ and Na+ conductances exist, whereas in guinea-pig gall-bladder both K+, Na+ and anion (Cl- and/or HCO3-) conductances are present; in both species conductive Na+ pathways are inhibited by amiloride. .

Amiloride↗
PubMed1982

Clinical program for screening and treatment of hypertension in veterans.

Hypertension clinics, in which primary care is provided by specially trained nonphysician therapists under physician supervision, can provide very effective and relatively inexpensive control of hypertension for large numbers of patients. Since 1972, 32 VA Hypertension Screening and Treatment Clinics have screened about 500,000 veterans, 29 percent of whom have had diastolic pressures of 90 mmHg or more and 13 percent of whom have had diastolic pressures of 105 mmHg or more. Of subjects who returned for a second visit, 77 percent continued to have diastolic pressures of 90 mmHg or more. Blacks had a higher percentage of severe hypertension than whites.Since treatment became available in these clinics in 1974, 25,000 veterans have been treated. Computerized data are available for 10,777 of them who began treatment during 1974, 1975, or 1976. Of those with at least five treatment visits during that period, half had diastolic pressures below 90 mmHg at their most recent visit, and 80 percent had diastolic pressures below 100 mmHg. Moreover visit adherence was high, with two thirds of those who began treatment in these clinics during their first six months of operation continuing that treatment for two and a half years.

Adult↗
PubMed1982

[Influence of curare and methohexital-Na on the content of energy-rich phosphates and substrates of glycolysis in rat liver (author's transl)].

Our investigations demonstrate that 7',12'-dihydroxy-6,6'-dimethoxy-2,2,2',2'-tetramethyl-tubocuraranium dihydroxide (D-tubocurarine, Curarin-Asta), in the following briefly called curare, and methohexital sodium influence glycolysis and energy metabolism of rat liver cells. Within the first 5 min after i.v. application of curare we observed a decrease of ATP levels due to either increased energy demands during cellular metabolism or to a decrease of ATP production in the respiratory chain. This effect was followed by an activation of glycolysis as demonstrated by a decrease of cytoplasmic glycogen and an increase of glucose-6-phosphate. Simultaneously, cytoplasmic lactate levels were increased and redox potentials significantly shifted. The latter effect is caused by alterations in the lactate-pyruvate ratios. In contrast, methohexital sodium induced a significant increase of cellular ATP levels. The observed low lactate-pyruvate ratio and the changes in the adenylate system following methohexital sodium suggest that this drug reduces energy consumption during cellular metabolism.

Adenosine Diphosphate↗