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Biomedical subjects

C Weiss

Publications and source records attributed to C Weiss.

At least 145 records · Page 8Linked to original sources
PubMed1995

Lymphocyte subpopulations and concentrations of soluble CD8 and CD4 antigen after anaerobic training.

In 13 middle-aged, moderately trained men (40-60 yr) we investigated the influence of anaerobic training on immunological parameters measured at rest. The 4 week anaerobic training program (two 30-min sessions weight lifting and one interval training per week; lactate levels 4-6 mM and 8-10 mM, respectively), caused a significant increase of the mean arm muscle force by 7% (handgrip test, p < 0.05). Evaluation of lymphocyte subsets was performed by means of three-colour immunofluorescence analysis (FACS). After 4 weeks of training we found a significant reduction of the CD4+ T-cell counts by 15% (p < 0.05) paralleled by a fall of naive cells (CD3+/CD4+/CD45RA+) by 16%, which, however, was statistically not significant. While percentages of CD3+ lymphocytes decreased significantly by 6% (p < 0.001), absolute numbers of CD3+ T-lymphocytes were not detectably affected and also the relative ratio of CD8+ T-cell subsets, i.e. the ratio of suppressor vs cytotoxic T-cells (CD3+/CD8+/CD11b+, CD3+/CD8+/CD11b- respectively) remained unchanged. Likewise the serum concentrations of the soluble CD8 and CD4 antigen (sCD8/sCD4) as determined by sandwich enzyme immunoassays were found to be unaffected. We conclude that 40-60 years old healthy human subjects performing anaerobic training experience on average a significant decrease of circulating CD4+ T-lymphocytes, while other parameters including the activation parameters sCD8 and sCD4 remained unchanged.

Adult↗
PubMed1995

Computed tomography in the detection of the vascular component in dementia.

We evaluated the presence and type of vascular lesions with computerized tomography (CT) in 94 cognitively impaired elderly patients who had been defined as degenerative (Alzheimer's disease, AD) or vascular (multi-infarct dementia, MID) dementia patients on the basis of clinical data. Twenty-six percent of the 77 AD, but only 59% of the 17 MID patients had vascular lesions. The most represented vascular lesions were leukoaraiosis in AD and hemispherical cortical lesions in MID patients. Age, signs indicative of, and risk factors for vascular disease were associated with vascular lesions on CT. We conclude that CT scan is a necessary complement to historical and clinical data in the detection of vascularity in demented patients.

Aged↗
PubMed1994

Effect of glutathione depletion and oral N-acetyl-cysteine treatment on CD4+ and CD8+ cells.

HIV-infected individuals and SIV-infected rhesus macaques have, on the average, decreased plasma cysteine and cystine concentrations and decreased intracellular glutathione levels. We show that the cysteine supply and the intracellular glutathione levels have a strong influence on the T cell system. A study of healthy human subjects revealed that persons with intracellular glutathione levels of 20-30 nmol/mg protein had significantly higher numbers of CD4+ T cells than persons with either lower or higher glutathione levels. Persons who moved during a 4-week observation period from the optimal to the suboptimal range (10-20 nmol/mg) experienced, on the average, a 30% decrease in CD4+ T cell numbers. This decrease was prevented by treatment with N-acetyl-cysteine (NAC). NAC caused this relative increase of CD4+ T cell numbers in spite of decreasing glutathione levels and not by increasing the glutathione level. Our studies suggest that the immune system may be exquisitely sensitive not only against a cysteine and glutathione deficiency but also against an excess of cysteine.

Acetylcysteine↗
PubMed1994

Identification of alpha-cardiac myosin heavy chain mRNA and protein in extraocular muscle of the adult rabbit.

Extraocular muscles contain both fast-twitch and multiply-innervated, tonic-contracting fibres. In rat, these fibres collectively express numerous myosin heavy chain isoforms including fast-type embryonic and neonatal, adult slow twitch type I and fast twitch type II, and a fast isoform unique to extraocular muscle. Immunocytochemical and Western blotting results are presented which suggest that, in rabbit, an additional species, the alpha-cardiac myosin heavy chain, is present. The immunoreactive species is found in all rabbit extraocular muscles and in the extraocular muscles is expressed in almost all fibres which do not contain a fast myosin heavy chain. Positive identification of this isoform as the alpha-cardiac myosin heavy chain was obtained by sequencing a cloned PCR product derived from extraocular muscle mRNA unique to the 3'-end of rabbit alpha-cardiac myosin heavy chain mRNA. This is the first unequivocal demonstration of alpha-cardiac myosin heavy chain expression in extraocular muscle.

Amino Acid Sequence↗
PubMed1994

Ipriflavone prevents the bone mass reduction in premenopausal women treated with gonadotropin hormone-releasing hormone agonists.

In the present study we assessed the effects of ipriflavone in the prevention of increased bone turnover and the rapid bone loss that follows medical induced hypogonadism caused by the administration of a gonadotropin hormone-releasing hormone agonist (GnRH-A). In a double blind, placebo-controlled study, ipriflavone (600 mg/day, tdd (three divided doses)) or identical placebo tablets were given with 500 mg/day of calcium to patients treated with 3.75 mg leuproreline acetate every 30 days, for 6 months. In placebo-treated subjects (n = 39), urinary hydroxyproline excretion and plasma bone GLA protein levels showed a substantial (P < 0.01) increase, while spine bone density and total body bone density significantly (P < 0.01) decreased after 3 and 6 months of GnRH-A administration. Conversely, in ipriflavone treated group (n = 39), no significant difference in bone markers and bone density was evidenced. These data indicate that ipriflavone can restrain the bone remodeling processes and prevent the rapid bone loss that follows medical induced hypogonadism. Thus, ipriflavone administration can be of value in the prevention of osteopenia in women treated with GnRH-A.

Adult↗
PubMed1994

A 'novel' infectious bronchitis strain infecting broiler chickens in Italy.

An outbreak of severe respiratory disease in flocks of broiler chickens was associated with the isolation of a 'novel' strain of infectious bronchitis virus (IBV). The isolate, designated 624/I, was isolated from 9 of the 11 flocks sampled. The results of cross neutralisation and haemagglutination-inhibition tests showed isolate 624/I to be antigenically distinct from several European and American strains. In a serological survey carried out on affected flocks, specific antibodies to IBV strain 624/I and turkey rhinotracheitis (TRT) virus were detected.

Animals↗
PubMed1994

Catheter-induced mechanical conduction block of right-sided accessory fibers with Mahaim-type preexcitation to guide radiofrequency ablation.

BACKGROUND: Accessory pathways originating at the tricuspid annulus that exhibit decremental antegrade conduction properties (Mahaim-type preexcitation) are amenable to radiofrequency (RF) current catheter ablation. However, a reliable and reproducible strategy for mapping and ablation of these fibers is lacking. METHODS AND RESULTS: Eleven patients with preexcited atrioventricular tachycardia involving a decrementally conducting antegrade accessory pathway underwent complete electrophysiological evaluation and subsequent attempts at RF catheter ablation. Mechanical conduction block at the subannular level of the atrial input to the accessory fiber was induced by catheter manipulation in 8 patients, in 2 of them during atrial fibrillation. RF current was delivered, after resumption of preexcitation, to the site of mechanical block during atrial pacing (n = 6) or atrial fibrillation (n = 2) and eliminated the accessory pathway in all 8 patients. In another patient, mechanical block was not observed, but ablation of the atrial accessory fiber insertion was achieved at the subannular level during atrioventricular tachycardia. The anatomic site of ablation along the tricuspid annulus was anterolateral (n = 1), lateral (n = 3), or posterolateral (n = 5). Failures were encountered in the first patient of the series in whom ablation attempts were directed at the ventricular insertion of the accessory fiber and in a patient in whom ablation of the atrial insertion was attempted at the supraannular level. Recurrence of preexcitation within 12 hours was observed in 5 of 6 patients in whom ablation had been achieved during atrial pacing. Eventually successful repeat sessions were performed the following day using a simplified ablation approach. Thus, a median of 5 RF pulses (range, 1 to 26) per accessory fiber eliminated conduction in 9 (82%) of the 11 patients in 1.9 +/- 0.9 sessions. During a follow-up of 9.5 +/- 2.3 months, preexcitation recurred in 1 patient. CONCLUSIONS: The atrial origin of accessory connections with Mahaim-type preexcitation is apparently confined to the anterolateral-to-posterolateral region of the tricuspid annulus. Mechanical conduction block in the atrial input to the accessory fiber induced at the subannular level by catheter manipulation provides an optimal marker to locate the ablation site, even during atrial fibrillation. To expose early recurrence of antegrade accessory pathway conduction, intermittent atrial pacing in the 12 hours after ablation is advisable; in cases of recurrence, a repeat procedure can readily be performed using just the ablation catheter advanced to the target site at the tricuspid annulus.

Adult↗
PubMed1993

Effects of temperature on the therapeutic efficacy and pharmacokinetics of ifosfamide.

The influence of tumor temperature (28, 32, 37, 39, 41, or 43 degrees C for 1 h) on the therapeutic efficacy of i.v. single bolus injections of ifosfamide (IFO) (32, 65, 125, or 250 mg/kg body weight) in human tumor xenografts (MX1 breast carcinoma) grown in nude mice (n = 240) was studied. Tumor temperature was controlled by water bath immersion. Sixty days after treatment the percentage of tumor-free survival was determined. For example, at 37 degrees C IFO in a dose of 65 mg/kg body weight led to 10% tumor-free survival in the treated animals. At 43 degrees C the same dose resulted in 60% tumor-free survival. A clear drug dose- and temperature-dependent increase of the therapeutic efficacy of an active oxazaphosphorine compound was also demonstrated in vitro. The concentrations of IFO and of 4-hydroxyifosfamide in blood and tumors at different body temperatures (controlled by water bath immersion) were determined over 120 min and WBC counts were obtained. The half-lives and the areas under the curve for IFO in blood were not significantly different at 37 degrees C and 41 degrees C. Since the half-life of IFO depends mainly on hepatic metabolism, the similarity of half-lives and of areas under the curve for IFO at 37 degrees C and 41 degrees C indicates a constant activation rate. However, significantly lower plasma concentrations of the activated drug at a liver (body) temperature of 41 degrees C, compared with 37 degrees C, were found, indicating a higher elimination rate. The concentration of the activated drug in the tumors within the initial 60 min at 41 degrees C, however, exceeded by > 2-fold that at 37 degrees C. The bone marrow toxicity of the same drug dose did not significantly increase with body temperature.

Animals↗
PubMed1993

Receptive fields of single cells from the face zone of the cat rostral dorsal accessory olive.

Natural stimulation was used to map the receptive fields of single cells recorded from the rostral medial portion of the dorsal accessory olive (rDAO) and the subjacent principal olive (PO) of the barbiturate anesthetized cat. Previous reports indicated a somatotopic mapping of the entire contralateral body within the rDAO which included a small face zone and a larger zone with a very precise map for the limbs. While concentrating on the face zone of the rDAO we confirmed the previously reported somatotopy (face: rostral and medial; forelimb: caudal and medial; hindlimb; caudal and lateral; and trunk: rostal and lateral) and found a somatotopy within, and adjacent to, the face zone. At the border between rDAO regions representing forelimb and face, cells with forelimb fields were found to lie dorsally to cells with facial fields. Within the rDAO face region, cells with large facial fields lie dorsally to cells with small facial fields. In both cases, the more ventral cells lie in the ventral lamella of the PO, which suggests a functional as well as physical continuity between rDAO and the ventral lamella of the PO. We therefore conclude that the face zone in the rDAO and the face zone in the PO form one continuous and complete map of the face with an orderly progression of receptive fields. Furthermore, we have found that stimulation of the red nucleus can inhibit rDAO cells with facial receptive fields just as it does cells with receptive fields from the rest of the body.

Animals↗
PubMed1993

Does salicylic acid increase the percutaneous absorption of diflucortolone-21-valerate?

The percutaneous absorption of diflucortolone-21-valerate (DFV) and its effect on the pituitary adrenal system were investigated during large skin area treatment (20 g ointment twice a day for 8 days) of two groups of healthy volunteers with Nerisona and Nerisalic ointment, respectively. Plasma levels of diflucortolone, cortisol and dehydroepiandrosterone (DHEA) were measured in both groups whereas plasma levels of salicylic acid were measured additionally in volunteers treated with Nerisalic. No differences, neither in percutaneous absorption of DFV nor in effects on cortisol and DHEA were found between the two treatment groups. There was a slight reduction in cortisol levels under both treatments, but the circadian rhythm was not disturbed. Mean salicylic acid plasma levels under high-dose topical Nerisalic treatment were about 50-fold below levels where toxicity may be expected.

Adult↗
PubMed1993

[Outpatient diuretic treatment of terminal heart failure by a completely implantable venous infusion system].

In severe heart failure with peripheral and enterohepatic congestion resistance to diuretics with inactivation of oral furosemide is a common finding. Impaired bioavailability is most likely related to pharmacodynamic and especially to pharmacokinetic reasons. To ensure efficient drug delivery and effective treatment with diuretics, venous access devices (port-systems) were implanted in 10 patients (eight men and two women, age between 57 and 80 years). All patients were in heart failure functional class III-IV and had a history of recurrent episodes of severe decompensation; none was suitable for heart transplantation. Injections of furosemide and other drugs were performed 1-4 times a day; one female patient performed the intravenous injections herself, in three cases the partners and in six cases the practitioner or an outpatient nurse performed the injections. All patients were treated on an outpatient basis, i.e., at home or in nursing homes. The port-implantation was followed up between 30 and 742 days (1-24 months); no serious complications were observed. Both patients and their partners were considered to well tolerate and accept the port-systems. Totally implantable venous access devices promise to reduce the number and severeness of cardiac decompensations in chronic preterminal heart failure by application of daily intravenous furosemide. This form of outpatient treatment will ameliorate the quality of life and stabilize the course of these severely and chronically ill patients.

Aged↗
PubMed1993

Clinical pharmacokinetics of 5-fluorouracil. Influence of the biomodulating agents interferon, dipyridamole and folinic acid alone and in combination.

The pharmacokinetics of the antimetabolite 5-fluorouracil (5FU, CAS 51-21-8) were investigated under the influence of the biomodulating agents folinic acid (FA), FA combined with dipyridamole (DPM), DPM, interferon-alpha-2b (IFN), and IFN combined with DPM. IFN as well as IFN/DPM cause an enormous increase of the 5FU plasma concentrations resulting in a statistically significant change of the pharmacokinetics. The mean initial plasma concentrations of 5FU are increased at about 143% under the influence of IFN and at 162% under the influence of IFN/DPM. Accordingly, the mean area under the concentration-time curve is elevated at 114% for IFN and at 184% for IFN/DPM. The volume of distribution (IFN - 39%, IFN/DPM - 38%) as well as the total body clearance (IFN - 30%, IFN/IFN - 44%) are lowered distinctly. In contrary, the coadministration of either FA or DPM or FA/DPM to 5FU does not lead to a significant change in the pharmacokinetic profile of 5FU, but also causes higher plasma concentrations. The present results indicate that the coadministration of biomodulators can lead to distinct changes of the 5FU kinetics, but must not be useful in each case.

Aged↗
PubMed1993

Membrane depolarization combined with release of calcium from internal stores does not trigger secretion from PC 12 cells.

The mechanisms underlying catecholamine release from pheochromocytoma (PC 12) cells were examined. Whereas application of 1 microM bradykinin (BK) induced an increase in intracellular calcium ([Ca2+])i), either in medium containing 1.8 mM Ca2+ or in medium prepared without the addition of CaCl2 ("Ca(2+)-free medium"), norepinephrine ([3H]NE) release was induced only in Ca(2+)-containing medium. Similarly depolarization by 50 mM potassium induced [3H]NE release only in 1.8 mM calcium-containing medium. The combination of membrane depolarization (50 mM KCl) with increased [Ca2+]i secondary to BK application in "Ca(2+)-free medium" did not induce catecholamine secretion. It was concluded that Ca2+ entry through calcium channels at the plasma membrane is essential for the activation of catecholamine release. A rise in [Ca2+]i (4-5 times x basal) released from internal stores is not sufficient to trigger secretion from PC 12 cells, either by itself or in combination with membrane depolarization.

Animals↗
PubMed1992

Stress-induced facilitation of classical conditioning.

Stress has been shown to impair subsequent learning. To determine whether stress would impair classical conditioning, rats were exposed to inescapable, low-intensity tail shock and subsequently classically conditioned under freely moving conditions with a brief periorbital shock unconditioned stimulus and a white noise conditioned stimulus. Unexpectedly stressed rats exhibited significantly more conditioned eyeblink responses and the magnitude of their individual responses was also enhanced. These results stand in contrast to the learning deficits typically observed and suggest that stress can enhance the acquisition of discrete conditioned responses.

Acoustic Stimulation↗
PubMed1992

Local hyperthermia enhances cyclophosphamide, ifosfamide and cis-diamminedichloroplatinum cytotoxicity on human-derived breast carcinoma and sarcoma xenografts in nude mice.

Antitumour response and toxicity of locally applied hyperthermia with or without cyclophosphamide, ifosfamide, and cis-diamminedichloroplatinum (cisplatin) have been compared. The model systems were human breast carcinoma (MX1/3) and human sarcoma (S117) grown in nude mice. In order to detect changes of tumour oxygenation intratumoral PO2 and pH were measured before, during and following hyperthermia. In both human tumour lines a monotherapy with one of the cytotoxic drugs or with hyperthermia caused a transient growth delay, while the combination of the same dose of the drugs with hyperthermia (at 43 degrees C for 1 h) resulted in complete tumour remissions. During hyperthermia, in both tumour types oxygenation was improved. Intratumoral pH remained practically unchanged.

Animals↗