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Biomedical subjects

R Fink

Publications and source records attributed to R Fink.

At least 91 records · Page 5Linked to original sources
PubMed1983

The effect of cellular energy reserves and internal calcium ions on the potassium conductance in skeletal muscle of the frog.

The increase in K+ conductance induced by repetitive stimulation in metabolically poisoned sartorius muscle fibres of the frog was investigated, using a two-micro-electrode voltage-clamp technique. After the inhibition of creatine kinase by 0.4 mM-1-fluoro-2,4-dinitrobenzene (FDNB) and a complete and irreversible exhaustion of contractility, a nearly linear current-voltage relation was measured between -100 and 0 mV. In the presence of CN- (4 mM) an 'intermediate state' could be established by repetitive stimulation towards complete mechanical exhaustion. In this labile state, the high and potential-independent K+ conductance could be induced by repetitive voltage-clamp pulses (100 ms duration) from -85 to 0 mV membrane potential. After the pulses had ceased, fibres regained their original membrane conductance within several minutes. After the electrophoretic injection of the Ca2+-chelating agent H2EGTA2- into fibres in the intermediate state, an increase in membrane conductance by repetitive voltage-clamp pulses could no longer be induced. Fibres in the intermediate state into which H2EGTA2- -buffered Ca2+ (free Ca2+ approximately 10(-5) M) was injected, or to which external caffeine (1.5 mM) was applied, showed a spontaneous and reversible increase in membrane conductance. In metabolically poisoned and mechanically exhausted sartorius muscles the concentrations of creatine phosphate (CP) and ATP were estimated using biochemical standard methods. The concentration of CP remained basically unchanged after FDNB poisoning. In solutions containing CN- plus iodoacetate CP fell below the detectable concentration of about 0.5-1% of the normal value. ATP decreased to slightly less than 20% under both conditions. It is concluded that internal free Ca2+ promotes the activation of the K+ conductance in exhausted muscle fibres, and that a shortage of energy reserves increases the 'sensitivity' of K+ channels to Ca2+ ions.

Adenosine Triphosphate↗
PubMed1983

Changes in the blood platelets of alcoholics during alcohol withdrawal.

The effects of alcohol withdrawal on platelet count and platelet function was studied sequentially in a group of alcoholics. Baseline values for platelet count, platelet adenine nucleotides and plasma beta-thromboglobulin (beta TG) level were within the normal range but platelet aggregability (especially with ADP and adrenaline) and circulating platelet aggregates were decreased for the group as a whole. After alcohol withdrawal there was a pronounced increase in all parameters measured which reached statistical significance in many cases and persisted for two to four weeks. The potential implications and possible mechanisms for these changes are discussed.

Adenosine Diphosphate↗
PubMed1983

[Blast crisis in chronic myeloid leukemia].

Although the worst prognosis among acute forms of leukemia is persistently attributed to the blast crisis of chronic myeloid leukemia, a therapeutic nihilism seems to us to be unreasonable. Even in the developing stage of a blast crisis we consider an aggressive chemotherapy to be justified particularly in younger patients. In this connection, value and necessity of supporting of therapy are especially emphasized. Remissions can be achieved in about one third of patients during the blast crisis of CML. As in other forms of tumour therapy, the initial status, age, and secondary diseases have to be taken into account and a careful, individual therapy planning has to be made. For the future there is the hope that the increasing possibilities of differentiating blasts will allow more systematic therapeutic conclusions to be made. According to the present knowledge the greatest hopes for achieving long-term remissions or even healings can, in our opinion, be expected by bone-marrow transplantation.

Adolescent↗
PubMed1983

[Clinical comparative trial of piretanide and furosemide in patients with advanced renal insufficiency. Drug levels and diuretic potency of single oral doses].

Piretanide is a new diuretic agent that is structurally related to bumetanide and furosemide. The effect of a single oral dose of piretanide 12 mg on the serum agent levels and diuretic activity was compared with that of Furosemide 80 mg p.o. in 12 patients with advanced renal insufficiency using a balanced randomized design. Piretanide was seen to have its most pronounced activity in the 1st h, while the effect of furosemide was more prolonged without abrupt peaks. There was a tendency of water conservation following the diuresis with piretanide, which produced a lesser response in volume and sodium excretion than furosemide when analysed as cumulative excretion at 24 h. The sodium-potassium ratio of the total urinary volume increased slightly by the same amount. Piretanide was approximately 5 times more potent on a weight basis than furosemide. Piretanide appeared to be effective in advanced renal insufficiency. Due to its rapid elimination effect piretanide as well as furosemide is also indicated for the treatment of renal edema in emergency situations.

Aged↗
PubMed1983

Transtracheal aspiration in pulmonary infection in children with cystic fibrosis.

Six transtracheal aspirations (TTA) and expectorated sputum specimens were collected from four children suffering from cystic fibrosis who had pulmonary infection. Specimens obtained from both sites were cultured for aerobic bacteria and TTA aspirates were also cultured for anaerobes. Differences in bacteria isolated in TTA and sputum aspirates were present in all instances. Six isolates were recovered in both sites (three Pseudomonas aeruginosa, two Staphylococcus aureus and one Aspergillus flavus). Five aerobic isolates were recovered only in the expectorated sputum and not in TTA aspirations (two Klebsiella pneumoniae and one each of P. aeruginosa, Escherichia coli and Proteus mirabilis). Nine organisms were isolated only from the TTA (two each of Veillonella parvula and Alpha hemolytic streptococci, and one each of Bacteroides fragilis, B. melaninogenicus, Lactobacillus sp., Haemophilus influenzae and Gamma hemolytic streptococci). The recovery of anaerobic organisms from four of the six TTA specimens suggests a possible role for these organisms in the etiology of pulmonary infection in cystic fibrosis. We found TTA to be helpful in the bacterial diagnosis and management of pulmonary infections in cystic fibrosis.

Adolescent↗
PubMed1981

Platelet hyperaggregability during alcohol withdrawal.

Platelet function was assessed before and one week after acute alcohol withdrawal in eighteen male alcoholics. Compared to normal male controls, the platelets of the alcoholics were slightly hypoaggregable on admission but became hyperaggregable one week after commencement of alcohol withdrawal therapy. The changes were most noticeable in those patients who were alcoholaemic on admission and when using ADP or adrenaline as aggregating agents. There was no consistent change in platelet counts or in platelet adenine nucleotide levels, both of which were normal.

Alcoholism↗
PubMed1981

Calcium depletion in frog muscle tubules: the decline of calcium current under maintained depolarization.

1. Ca2+ currents in frog skeletal muscle fibres were studied with a voltage-clamp technique. Under membrane depolarization maintained for several seconds, Ca2+ current was found to decline with time constants of 0.2-2 sec when [Ca2+]o = 10 mM. 2. Ca2+ currents are diminished by nifedipine, D-600, tetracaine and Ni2+. 3. When peak current is diminished by making the membrane potential positive, by block with drugs or by substituting the relatively less permeant Mn2+ for Ca2+ then the rate of decline is diminished also. When peak current is increased by recording at relatively negative membrane potentials or by substituting for Ca2+ the more permeant ions Ba2+ or Sr2+, then the rate of decline is increased in proportion. Evidently, the size of the current determines the rate of decline. 4. Decline of current is greatly slowed in isotonic Ca2+ saline or when the [Ca2+]o is buffered by the organic anion malate. These findings indicate that the decline of current arises from Ca2+ depletion in an extracellular compartment, most probably the transverse tubules. On this basis, an analysis of Ca2+ current decline and recovery leads to the following conclusions. 5. Ca2+ current flows almost entirely across the membranes of the transverse tubules. 6. After allowing for the tortuosity of the tubular network, the apparent diffusion coefficient for Ca2+ in the transverse tubules is about 2.6 X 10(-6) cm2/sec, three times less than the diffusion coefficient for K+ in the transverse tubules and about three times less than the diffusion coefficient for Ca2+ in free solution. 7. The transverse tubule lumen does not appear to have a large Ca2+-buffering capacity in the millimolar range. At [Ca2+]o = 10 mM, the tubule lumen binds less than 0.6 dissociable Ca2+ ions for every free ion.

Animals↗
PubMed1981

[Reoxygenation in a transplantable murine fibrosarcoma (author's transl)].

The fibrosarcoma SSK31 was irradiated under ambient or hypoxic conditions either acutely or at various intervals after a priming dose of 13 Gy. The absence of local recurrences was determined. The hypoxic fraction and the time course of reoxygenation were calculated on the basis of a comparison of the cure curves.

Animals↗
PubMed1980

[The so-called partial synchronization in the treatment of malignant lymphomas. A clinical study].

In a randomized study the effectiveness of a modified MOPP scheme (CVPP scheme) and a so-called partial synchronisation treatment (vincristine or vinblastine respectively and cyclophosphamide) was compared in 72 patients predominantly pretreated with Hodgkin lymphomas and non-Hodgkin lymphomas. From 49 patients affected with lymphogranulomatosis of stage IIIB and IV, 24 were treated according to CVPP scheme; in 10 of them a complete remission was achieved and in 4 of them a partial remission. 25 patients were treated in the control group with synchronization therapy. In 13 of them a complete remission and in 12 of them a partial remission was achieved. With CVPP therapy the mean remission time amounted to 14.4 months and with synchronization therapy 9.2 months. There was no significant statistical difference. From 23 patients with advanced non-Hodgkin lymphomas of a high malignancy 11 received a therapy with CVPP scheme; 2 of them came into a complete remission and 3 of them into a partial one. 12 patients received a synchronization therapy; 7 of them came into a partial remission. With CVPP therapy the mean remission time amounted to 14.4 months, with partial synchronization therapy--10.8 months. Even in non-Hodgkin lymphomas there was no significant difference between the forms of therapy used. Even a comparison of the two survival times of both forms of treatment does not reveal any significance. Thus, both procedures of treatment seem to be comparable in their therapeutic efficaciousness, even if the number of complete remissions during the treatment with CVPP scheme was greater in our investigations. The assumed lower toxicity of synchronization therapy could not be confirmed by our study. In addition to the controversial synchronization effect, the good efficaciousness of treatment according to the so-called synchronization therapy may be due to sensibilizing phenomena and recruitment phenomena.

Bleomycin↗
PubMed1980

The effect of energy deprivation and hyperosmolarity upon tubular structures and electrophysiological parameters of muscle fibres.

The exhaustion of metabolically poisoned muscle fibres is accompanied by a one hundred-fold increase in potassium conductance. Under these conditions a normal membrane capacity was measured. Extracellular markers (lanthanum, ferritin) were traced in the transverse tubular system but not in the myoplasm or the sarcoplasmic reticulum. These results show that the structural integrity of surface and tubular membranes is fully maintained. The exhausted muscle can, therefore, be introduced as a suitable preparation for an analysis of the potassium channel, the alterations of ion concentrations in the restricted area of the T-system and other phenomena of physiological interest. Further experiments with extracellular markers dealt with the structure of the triads. Earlier measurements by other authors suggested a continuity between lumina of the T-system and the sarcoplasmic reticulum, at least after an exposure to hyperosmotic solutions. These results could not be confirmed.--In addition the distribution of fibre cross areas of sartorius muscle was analysed from cryosections.

Animals↗
PubMed1980

Na/K selectivity, ion conductances and net fluxes of K+ and Na'n metabolically exhausted muscle fibres.

The high resting potassium conductance, induced by stimulating skeletal muscle fibres of the frog to complete exhaustion of contractile activity, was investigated in more detail. In exhausted fibres the Na/K-selectivity (alpha = PNa/PK) calculated by applying the equation for zero-current potentials (Goldman, Hodgkin, Katz) remained as high or became even larger than in normal fibres (alpha less than 0.009). Net fluxes of Na and K derived from a flame photometric estimation of the internal concentrations of these ions rose for Na to 24-49 and for K to 50-100 pmole/(cm2.s). The measured fluxes were by up to more than two orders of magnitude smaller than those calculated from the Goldman-Hodgkin-Katz flux equation based upon the high potassium conductance measured with electrophysiological methods. This discrepancy may be explained by assuming that these channels do not obey the 'independence principle'. The results can probably better be interpreted in terms of multi ion channels with single file characteristics, although accumulation of potassium ions in the transverse tubular system or in the vicinity of the surface membrane may partly account for the observed deviation.

Animals↗
PubMed1979

[Prognosis of lymphogranulomatosis (stage III B-IV) treated with drugs--results of a retrospective 10 year study].

With the help of survival curves of 91 patients with histologically ascertained lymphogranulomatosis a report on experiences concerning the prognostic importance of different factors is given. The examination is based on a retrospective analysis of a well documented number of patients who were chemotherapeutically treated from 1967--1976 in the medical outpatient department and the medical clinic of the Erfurt Academy of Medicine. We found on the basis of the retrospective study that the following factors deteriorate the prognosis: Clinical stage IV, presence of general symptoms, type poor in lymphocytes. Older age at making the diagnosis as well as male sex also reveal a worse prognosis as to the 3-year-survival rate than the comparative groups. Furthermore it was shown that the quality of remission after initial chemotherapy is of decisive prognostic valency. When cytostatic combination schemata were used for the induction of the remission the survival rates could be improved. The problems of the remission-keeping chemotherapy are entered.

Adult↗
PubMed1979

Mental health services for Medicaid enrollees in a prepaid group practice plan.

The authors present the patterns of utilization of mental health services of a low-income population in a prepaid group practice setting, the Health Insurance Plan of Greater New York (HIP). Over a 6-year period, utilization rates for psychiatric consultations and mental health services by Medicaid enrollees rose to equal or exceed utilization by employed groups. The authors also provide evidence that psychiatric treatment reduces the use of other physician services, especially X-ray and laboratory services.

Adult↗
PubMed1979

Hysterical psychosis and hypnotizability.

The very existence of hysterical psychosis as a diagnostic entity has been questioned as part of the general difficulty in defining both hysteria and psychosis. However, several recent investigations have documented a syndrome that usually involves brief and intense periods of psychotic behavior, generally with graphic decompensation, severe environmental stress, and rapid recompensation, in individuals with other hysterical features. The authors assert that such a syndrome does exist as a clinical entity and that the differential diagnosis can be facilitated by using a standardized measure of hypnotic trance capacity. They hypothesize that patients with hysterical psychosis are highly hypnotizable, while those who are schizophrenic and psychotic have low hypnotizability. The authors review the literature and present two case examples.

Adolescent↗
PubMed1979

Detection of alcoholic cardiomyopathy by serum enzyme and isoenzyme determination.

Serum creatine kinase and lactate dehydrogenase isoenzymes were studied in 73 patients with alcoholism, including two patients with clinical alcoholic cardiomyopathy and 28 patients with haemodynamic evidence (systolic time interval abnormality) of disordered myocardial function. No isoenzyme abnormalities suggestive of myocardial injury were observed. We conclude that isoenzyme examination is unsuitable for the early detection of myocardial damage from alcohol.

Adult↗