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Biomedical subjects

H Fischer

Publications and source records attributed to H Fischer.

At least 217 records · Page 12Linked to original sources
PubMed1995

cAMP-independent activation of CFTR Cl channels by the tyrosine kinase inhibitor genistein.

Genistein, a protein tyrosine kinase inhibitor, activates the cystic fibrosis transmembrane conductance regulator (CFTR) in transfected NIH-3T3 fibroblasts that express the CFTR (3T3-CFTR). CFTR activity was assayed by 125I efflux and by patch clamping in the cell-attached mode. Both forskolin and genistein stimulated 125I efflux and activated a 9-10 pS anion channel in 3T3-CFTR cells but failed to activate 125I efflux in mock-transfected NIH-3T3 cells. Genistein, unlike forskolin and 3-isobutyl-1-methylxanthine, did not increase intracellular adenosine 3',5'-cyclic monophosphate (cAMP) above control levels. This demonstrates that genistein-dependent activation does not involve inhibition of phosphodiesterase activity and suggests that stimulation does not involve a direct activation of protein kinase A. Genistein stimulated 125I efflux to approximately 50% of the maximal rate with forskolin. Genistein did not increase 125I efflux at saturating forskolin but decreased the concentration of forskolin required for half-maximal stimulation. Orthovanadate (VO4), a phosphotyrosine phosphatase inhibitor, inhibited genistein-induced channel activation with an inhibition constant of approximately 20 microM. These effects suggest that, in addition to activation by protein kinase A, the CFTR is regulated by a tyrosine kinase-dependent pathway.

1-Methyl-3-isobutylxanthine↗
PubMed1995

Chronic granulomatous disease assessed by single-cell granulocyte oxidative burst activity.

Here we report on a case of chronic granulomatous disease (CGD) in a 3-year-old boy who suffered from severe repeated bacterial infections including multiple liver abscesses. The case is of interest because (1) the disease is very rare (it is the first case of CGD diagnosed at the Clinic for Pediatric Medicine, University of Innsbruck), (2) the diagnosis, based on clinical parameters and the nitrobluetetrazolium test was completed and validated by single-cell measurements of respiratory-burst activity of the patient's granulocytes in a fluorescence-activated cell sorter (FACS), and (3) the applied FACS method, adapted in our laboratory, presents one of the most sensitive and reliable methods to evaluate this aspect of disturbed granulocyte function.

Cell Separation↗
PubMed1995

[Experimental ultrasound angioplasty: in vitro resolution of thrombi].

A new ultrasonic angioplasty ablation catheter connected to a 19.5 kHz. 25 W transducer was tested in vitro for its ability to disrupt 12-h. 24-h, and 5-day-old whole blood thrombi (n = 45.697 mg +/- 223 mg) and fibrin thrombi (n = 45.338 mg +/- 133 mg), as well as 5-day-old cadaver thrombi (n = 8.270 mg +/- 71 mg) within 10 min. Five of each age were used as control thrombi in which the catheter was moved back and forth without ultrasound emission. The size of ablated thrombus particles was measured by a laser device. The power output at the end of the catheter was assessed calorimetrically. The loss of weight of whole blood thrombi was between 429 (74%) and 524 mg (91%) (p < 0.01, whole blood thrombi vs. control thrombi) and between 302 (85%) and 314 mg (95%) (p < 0.05) for fibrin thrombi, respectively. Thrombus age did not prove to be a highly significant influencing factor. The disruption rate for whole blood thrombi was 0.75 to 1.05 mg/s and for fibrin thrombi 0.69 to 0.7 mg/s. It was only 0.09 mg/s for the cadaver thrombi. 93% of all particles ablated from whole blood thrombus ranged between 0-5 micron, less than 0.2% between 30-150 microns. For fibrin thrombi 69% of all particles were < 10 microns (25% between 10-20 microns). Only 0.02% ranged between 300-600 microns, which was similar for cadaver thrombi. The mean measured power output at the catheter tip was 5.9 W compared to the power output of 25 W at the ultrasound generator.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1994

A point mutation within the ATP-binding site inactivates both catalytic functions of the ATP-dependent protease La (Lon) from Escherichia coli.

A point mutant in the ATP-binding motif (GPPGVGK362T) of the ATP-dependent protease La from Escherichia coli was investigated in which the lysine at position 362 was replaced by an alanine. The catalytic efficiency of the K362A mutant is at least two orders of magnitude lower than that of wild-type protease La due to a decreased Vmax and an increased KM for ATP. Simultaneously, the peptidase activity of La K362A is almost completely eliminated. Since selective inactivation of the peptidase activity of La does not affect its intrinsic ATPase activity, coupling of proteolysis with ATP hydrolysis is only uni-directional in this energy-dependent protease.

ATP-Dependent Proteases↗
PubMed1994

[Successful therapy of a postpartum lymphangioleiomyomatosis. Case report and literature review].

Immediately after delivery a 17-year-old Turkish primipara developed edema, supraclavicular lymphoma and pleural effusion. CT-scans showed massive abdominal and mediastinal lymphoma. Lymphangioleiomyomatosis (LAM) was diagnosed by supraclavicular and retroperitoneal biopsy and progesterone receptors were documented in the tumor. There was no evidence of pulmonary involvement. 5 months' treatment with the LHRH-analogue goserelin showed neither clinical improvement nor regression of LAM. Irradiation of the ovaries and the abdomen with 30.2 Gy was followed by amenorrhea without immediate tumor remission. A follow-up examination 1 year later revealed clinical improvement and CT scans showed 50% abdominal and mediastinal regression of LAM. 5 1/2 years after diagnosis the asymptomatic patient is still in partial remission. Successful treatment of LAM is rare. We describe a case in which a major tumour reduction was documented by CT scanning.

Adolescent↗
PubMed1994

Bicarbonate conductance and pH regulatory capability of cystic fibrosis transmembrane conductance regulator.

The cystic fibrosis transmembrane conductance regulator (CFTR) is an epithelial Cl- channel regulated by protein kinase A. The most common mutation in cystic fibrosis (CF), deletion of Phe-508 (delta F508-CFTR), reduces Cl- secretion, but the fatal consequences of CF have been difficult to rationalize solely in terms of this defect. The aim of this study was to determine the role of CFTR in HCO3- transport across cell membranes. HCO3- permeability was assessed from measurements of intracellular pH [pHi; from spectrofluorimetry of the pH-sensitive dye 2',7'-bis(2-carboxyethyl)-5-(and -6)carboxyfluorescein] and of channel activity (patch clamp; cell attached and isolated, inside-out patches) on NIH 3T3 fibroblasts and C127 mammary epithelial cells transfected with wild-type CFTR (WT-CFTR) or delta F508-CFTR, and also on mock-transfected cells. When WT-CFTR-transfected cells were acidified (pulsed with NH4Cl) and incubated in Na(+)-free (N-methyl-D-glucamine substitution) solutions (to block Na(+)-dependent pHi regulatory mechanisms), pHi remained acidic (pH approximately 6.5) until the cells were treated with 20 microM forskolin (increases cellular [cAMP]); pHi then increased toward (but not completely to) control level (pHi 7.2) at a rate of 0.055 pH unit/min. Forskolin had no effect on rate of pHi recovery in delta F508 and mock-transfected cells. This Na(+)-independent, forskolin-dependent pHi recovery was not observed in HCO3-/CO2-free medium. Forskolin-treated WT-CFTR-transfected (but not delta F508-CFTR or mock-transfected) cells in Cl(-)-containing, HCO3(-)-free solutions showed Cl- channels with a linear I/V relationship and a conductance of 10.4 +/- 0.5 pS in symmetrical 150 mM Cl-. When channels were incubated with different [Cl-] and [HCO3-] on the inside and outside, the Cl-/HCO3- permeability ratio (determined from reversal potentials of I/V curves) was 3.8 +/- 1.0 (mean +/- SEM; n = 9); the ratio of conductances was 3.9 +/- 0.5 (at 150 mM Cl- and 127 mM HCO3-. We conclude that in acidified cells the WT-CFTR functions as a base loader by allowing a cAMP-dependent influx of HCO3- through channels that conduct HCO3- about one-quarter as efficiently as it conducts Cl-. Under physiological conditions, the electrochemical gradients for both Cl- and HCO3- are directed outward, so CFTR likely contributes to the epithelial secretion of both ions. HCO3- secretion may be important for controlling pH of the luminal, but probably not the cytoplasmic, fluid in CFTR-containing epithelia. In CF, a decreased secretion of HCO3- may lead to decreased pH of the luminal fluid.

3T3 Cells↗
PubMed1994

Activated monocytes kill malignant brain tumor cells in vitro.

The purpose of our study was to investigate the susceptibility of human glioblastoma multiforme (GBM) cells to lysis by human peripheral-blood monocytes following activation with biological response modifiers (BRM) and to lysis by various BRMs directly. Cytotoxic effects were determined using a monocyte-/BRM-mediated tumor cytotoxicity assay. Human peripheral-blood monocytes from healthy donors were activated in vitro by incubation for 24 h with different BRMs such as gamma- and beta-interferon (gamma, beta-IFN), lipopolysaccharide (LPS), muramyldipeptide (MDP) and tumor necrosis factor-alpha (TNF-alpha) in varying concentrations and combinations. Seven human GBM cell lines as well as an adenocarcinoma brain metastasis cell line and a malignant melanoma cell line served as target cells. Radiolabeled target cells were cocultivated with activated monocytes or with BRMs directly. Cytotoxicity was calculated after 72 h of cocultivation. High levels of cytotoxicity were mediated by monocytes activated with beta-IFN in six out of eight brain tumor cell lines and with TNF-alpha in five cell lines. The combination of two BRMs, in particular the combination of gamma-IFN + beta-IFN and gamma-IFN + TNF-alpha, was associated with an enhanced monocyte mediated lysis exceeding LPS control, whereas the combination of gamma-IFN + MDP was very effective against the metastasis cell line. Monocyte-mediated cytotoxicity against tumor target cells was up to ten fold higher than direct cytotoxicity of soluble BRMs. Our data indicate that BRM-stimulated peripheral-blood monocytes exert cytotoxic properties against human glioblastoma cells in vitro, which exceed those of BRMs alone up to ten fold. The higher tumoricidal activities observed after stimulation with combined BRMs suggest mutual promoting mechanisms of BRMs acting on the stimulation of lyctic activity in human peripheral blood monocytes.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1994

Release of acetylcholine in the ventral striatum is influenced by histamine receptors.

To investigate whether histamine receptor ligands influence the in vivo-release of acetylcholine in the ventral striatum, this brain region was superfused with histamine receptor agonists or antagonists through a push-pull cannula and drug effects on the release of acetylcholine were investigated. Histamine, the H1 receptor agonist 2-thiazolyl-ethylamine and the H3 receptor antagonist thioperamide enhanced acetylcholine release, while the H3 receptor agonist (R)-alpha-methylhistamine was ineffective. The results indicate that H1 receptors and H3 receptors modulate acetylcholine release. The thioperamide-induced increase of acetylcholine release might be exerted via H3-receptors located on cholinergic terminals. Alternatively, thioperamide might enhance acetylcholine release by increasing endogenous histamine release via H3 autoreceptors. It is concluded that, via stimulation of striatal H1- and H3 receptors, histaminergic neurons are involved in the regulation of cholinergic neuronal activity in the ventral striatum.

Acetylcholine↗
PubMed1994

Expression of neu/c-erbB-2 in human brain tumors.

The neu/c-erbB-2 oncogene encodes a 185 kd transmembrane protein (p185). Here we have used the monoclonal antibody (mAb) 3B5 to determine the expression of p185 in a series of fixed biopsy specimens of 180 human brain tumors, including the most frequent entities and, in addition, 18 recurrent gliomas with malignant progression. In summary, 3B5 immunoreaction was most prominent in astrocytomas of different grades of malignancies and in meningiomas. In World Health Organization (WHO) grade II astrocytomas mab 3B5-immunoreaction was related to the cytomorphological phenotype. Fibrillary astrocytomas showed no or only a weak immunoreaction (four of five, 80%) in contrast with protoplasmic or gemistocytic astrocytomas, where a strong reaction was observed in most cases (six of nine, 66.6%, and four of five, 80%, respectively). In WHO grade II to WHO grade IV astrocytomas a trend towards higher scores with increasing grade was found. In a limited number of cases (18 gliomas and two meningiomas) of the tumor series tested other mAbs against neu/c-erbB-2 epitopes, especially the mabs 9G6 and CB11, gave qualitatively comparable results. In WHO grade I pilocytic astrocytomas a wide range of 3B5 immunoreactivity has been observed. The results of in situ hybridization using a 32P-labeled neu/erbB-2 RNA probe performed on four WHO grade I and II astrocytomas, seven WHO grade IV glioblastomas, one WHO grade II oligoastrocytoma, one WHO grade III anaplastic astrocytoma, and three WHO grade I meningiomas were consistent with these immunomorphological data, and Northern blot analysis also indicated an overexpression of neu/c-erbB-2 mRNA in gliomas of different grades of malignancy and in meningiomas. These elevated neu-erbB-2 transcript levels occurred in the absence of gene amplification. In a second series of recurrent gliomas with malignant progression (n = 18) the higher 3B5-immunoreaction scores were apparent in the more malignant recurrent gliomas. In this series the overexpression of neu/c-erbB-2 parallels glioma progression. In our cases it was not, however, correlated with the postoperative relapse-free interval or with the overall length of survival.

Adult↗
PubMed1994

CFTR displays voltage dependence and two gating modes during stimulation.

The patch-clamp technique in conjunction with current noise analysis was employed to clarify the events underlying the regulation of the CFTR (cystic fibrosis transmembrane conductance regulator) during cAMP-dependent stimulation. 3T3 fibroblast cells expressing the CFTR were stimulated in cell-attached mode with forskolin. The number (N) of activated channels per patch ranged from 1 to approximately 100. In true single-channel recordings, CFTR's gating was best described by two open states (approximately 5 and approximately 100 ms) and three closed states (< or = 5, approximately 100, and approximately 1,000 ms). Current noise analysis resulted in spectra containing two distinct Lorentzian noise components with corner frequencies of 1.3 Hz and approximately 50 Hz, respectively. Single-channel time constants were dependent on voltage. The fastest closed state increased its contribution from 48% at +100 mV to 87% at -100 mV, and the medium open state reduced its length to one half, resulting in gating dominated by fast events. Similarly, the fast Lorentzian increased its amplitude, and its corner frequency increased from 44 Hz at +100 mV to 91 Hz at -100 mV, while the slow Lorentzian was voltage independent. In multi-channel recordings N.Po (i.e., N times open probability) increased significantly, on average by 52% between -90 and +90 mV. Stimulation with forskolin increased Po of CFTR to approximately 0.5, which resulted from a decrease of the longest closed state while the faster open and closed states were unaffected. Neither corner frequency was affected during stimulation. Recordings from multichannel patches revealed in addition, unique, very long channel openings (high Po mode, average 13 s). Channels exhibiting high Po (i.e., Po approximately 1.0) or low Po (i.e., Po approximately 0.5) gating modes were both present in multichannel recordings, and CFTRs switched modes during stimulation. In addition, the switch to the high Po mode appeared to be a cooperative event for channel pairs. High forskolin concentration (i.e., 10 microM) favored transition into the high Po mode, suggesting a cellularly mediated regulation of model switching due to a fundamental change in configuration of the CFTR. Thus, during stimulation the CFTR increased its activity through two distinct effects: the reduction of the long closed state and modal switching to the high Po mode.

3T3 Cells↗
PubMed1994

History of in utero cocaine exposure in language-delayed children.

To determine whether children with language delays are more likely to have been exposed to cocaine in utero than children with normal language development, a case-control study was undertaken. Based on routine office screening in our primary-care clinic over a 1-year period, we identified 29 consecutive children, aged 24 to 48 months, as language-delayed. They were compared with an approximate 2:1 match of children without language delay who had been seen in the clinic on the same days and who were of similar age. There was more reported cocaine use during pregnancy (six of 29, 21%) among the language-delayed children than among the controls (five of 71, 7%). This difference is statistically significant (P < 0.05, chi 2 = 3.92; odds ratio = 3.4 +/- 2.2). Discriminant analysis revealed that both cocaine and nicotine exposure were associated with delayed language development--with an unexpected negative, i.e., an antagonistic, protective, interactive effect (F[3,96] = 4.66, R2 = 12.7%, P < .005); neither gender nor caretaker contributed to language development in this sample. These results suggest that children with language delay detected in a clinical setting are more likely to have been exposed in utero to cocaine than children with normal language development. Prenatal cocaine exposure should be a risk factor in monitoring development in children.

Case-Control Studies↗
PubMed1994

Hepatic arterial infusion of floxuridine, leucovorin, doxorubicin, and cisplatin for hepatocellular carcinoma: effects of hepatitis B and C viral infection on drug toxicity and patient survival.

PURPOSE: To conduct a pilot trial of hepatic arterial infusion (HAI) of floxuridine (FUDR), leucovorin, Adriamycin (doxorubicin; Adria Laboratories, Columbus, OH), and cisplatin (FLAP) in nonresectable hepatocellular cancer (HCC) confined to the liver and assess the effects of hepatitis B (HBV) and hepatitis C (HCV) viral markers on toxicity, response to treatment, and patient survival. PATIENTS AND METHODS: Of 31 HCC patients, 13 were HBV- and HCV-nonreactive, and 18 had evidence of either current or prior HBV and/or HCV infection. Treatment was delivered through percutaneous hepatic arterial catheters, and Infusaid pumps (Shiley Infusaid, Norwood, MA) were placed in responding patients. Cisplatin (100 mg/m2) and Adriamycin (30 to 35 mg/m2) were administered on day 1, followed by a continuous 24-hour HAI of an admixture of floxuridine (60 mg/m2) and leucovorin (15 mg/m2) daily for 4 days. Treatment was repeated every 5 weeks. RESULTS: Twelve (41%) of 29 assessable patients had a partial response (PR), with a median time to disease progression of 13 months. Six (50%) of 12 HBV-negative (HBV-)/HCV-negative (HCV-) and six of 17 (35%) HBV-positive (HCV+) and/or HCV-positive (HCV+) patients achieved a PR. Eight patients have been maintained in remission for a median duration greater than 15.5 months. The median survival duration of all 31 patients was 15 months, 7.5 months among HBV+ and/or HCV+ patients, and significantly longer among hepatitis-non-reactive patients (P = .007). (A median has not yet been reached.) Granulocylopenia (< 0.1 x 10(3)/microL), thrombocytopenia (< 25 x 10(3)/microL), and hospitalizations for infectious complications were significantly more common among HBV-HCV-reactive than -nonreactive patients: 56%, 50%, and 67% versus 15%, 15%, and 8%, respectively (P < .05 for all). CONCLUSION: HAI of FLAP has induced long-term PR and has palliated extensive nonresectable HCC. Positive hepatitis serology appeared to increase bone marrow susceptibility to myelotoxic drugs. Conceivably, one or both viruses may have a direct inhibitory effect on bone marrow progenitors and thereby contribute to the observed myelotoxicity.

Aged↗
PubMed1994

Oral-facial-digital syndrome II. Transitional type between Mohr and Majewski syndrome: report of a new case with congenital stenosis of the trachea.

We present a female patient with laryngeal anomalies, tracheostenosis and pre- and postaxial polydactyly. Bilateral duplication of the hallux, polydactyly of hands, growth retardation and conductive hearing defect are consistent with oral-facial-digital (OFD) type II syndrome. Three similar cases of OFD syndrome with hypoplasia of the larynx, epiglottis and/or trachea without tibial dysplasia have been previously reported by Silengo and Temtamy and McKusick. The present patient adds one more case to this group of variants of OFD syndrome. We believe that those cases may be considered to form a separate subentity of OFD syndromes although overlapping features within the different subtypes make a precise classification very difficult.

Diagnosis, Differential↗