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Biomedical subjects

C Weiss

Publications and source records attributed to C Weiss.

At least 109 records · Page 6Linked to original sources
PubMed1997

Characterization of the myosin heavy chains of avian adult fast muscles at the protein and mRNA levels.

High resolution anion-exchange chromatography of myosin subfragment-1 in avian fast muscles revealed five fast heavy chains (I-V) expressed in muscle-specific patterns. Sequence analysis of a unique peptide established that the proteins differed in primary structure and suggested correlation with heavy chain genes identified independently by Robbins and coworkers. The identities of the isoforms and their expression patterns were confirmed at the mRNA level by a reverse-transcription, 5'-anchored PCR procedure. The fast white pectoralis major muscle possessed heavy chain I, the posterior latissimus dorsi muscle, of similar fibre type, expressed heavy chains I, III and IV. The fast red adductor superficialis muscle expressed either, or both, of heavy chains II and IV. The lateral gastocnemius muscle, of mixed fibre type, expressed heavy chains II-V. In general, heavy chains I, III and V appeared to be favoured in fast white fibres, while heavy chains II and IV were characteristic of fast red fibres. These results imply a greater subtlety of fast muscle function than has previously been appreciated.

Amino Acid Sequence↗
PubMed1997

Tachyarrhythmias following coronary artery bypass graft surgery: epidemiology, mechanisms, and current therapeutic strategies.

The distribution pattern of perioperative complications of coronary artery bypass graft surgery (CABG) is currently changing, due to the fact that it has become a routine operation with an increasing proportion of patients older than 70 years. Supraventricular and ventricular tachyarrhythmias are among the most commonly observed postoperative adverse events following CABG. The aim of this review is to give an update on epidemiology and mechanisms of postoperative arrhythmias and to present current diagnostic tools and therapeutic strategies.

Anti-Arrhythmia Agents↗
PubMed1997

Triazine dyes inhibit HIV-1 entry by binding to envelope glycoproteins.

We have attempted to purify envelope (Env) glycoproteins of human immunodeficiency virus (HIV) from the culture supernatants of CHO-Sec cells that secreted truncated 140-kDa precursor and mature 120-kDa Env glycoproteins. The concentrated culture supernatants were applied to a column coupled with cibacron blue 3GA (CB3GA) to separate albumin from the Env proteins because CB3GA, a triazine dye, has been known to have a high affinity to albumin. Unexpectedly, Env proteins as well as albumin bound to the column, and the bound Env proteins were eluted by increasing the ionic strength using KCl. Gp120 was eluted at 0.5-0.9 M of KCl, while a higher concentration (0.9-1.5 M) was necessary for the elution of gp140. The agarose gel coupled with reactive red 120 (RR120), another triazine dye with similar characteristics, also retained both Env proteins, and the bound Env proteins could be eluted in a similar manner. In addition, these agents inhibited syncytium formation caused by HTLV-IIIB and HTLV-IIIMN. Inhibition was also seen when a virus-free fusion assay between Env protein expressed in CHO cells and fluorescent labeled SupT1 cells were used. These findings indicate that triazine dyes bind to the functional regions of Env proteins of HIV-1 that play important role(s) for HIV infection.

Albumins↗
PubMed1997

Mapping of the coronary sinus and great cardiac vein using a 2-French electrode catheter and a right femoral approach.

INTRODUCTION: Local electrograms recorded from the coronary sinus and great cardiac vein provide important information for the diagnosis of various arrhythmias and identification of target sites for ablation of left-sided accessory pathways. One limitation of present techniques is the inability, in many cases, to probe the great cardiac vein at the anterior mitral annulus. We tested the feasibility of a new technique for catheterization of the coronary sinus and great cardiac vein by means of a small-diameter electrode catheter advanced via a right femoral approach through an angiography catheter. METHODS AND RESULTS: Of 22 patients (12 men and 10 women; ages 44.5 +/- 13.4 years) undergoing radiofrequency ablation of a supraventricular tachycardia, cannulation of the coronary sinus orifice using a 6-French 1L or 2L Amplatz catheter was achieved in 20 patients (91%) within 0.9 +/- 0.6 minutes; after cannulation, a 2-French octapolar electrode catheter with a soft radiopaque tip and a 3-mm interelectrode distance could be advanced in all 20 patients through the guiding catheter to the great cardiac vein in the anterior region of the AV sulcus within 0.8 +/- 0.7 minutes. Atrial and ventricular local potentials were recorded all along the mitral annulus during sinus rhythm, atrial and ventricular pacing, or supraventricular tachycardia. Variation of local potential amplitude never exceeded 20% of the mean and presented similar stability at all annular regions. The arrhythmogenic substrate was identified in all patients. Of 18 patients with 21 left-sided accessory pathways, an accessory pathway potential could be recorded at the ablation site by one or more adjacent epicardial electrode pairs in 10 pathways. No procedure-related complications were observed. CONCLUSIONS: The technique introduced in this study proved feasible in 91% of patients. Its main advantages are the simplicity and rapidity of coronary sinus cannulation and the ability to advance the electrode catheter to the anterior cardiac vein. In addition, closely spaced bipolar electrograms resulted in enhanced atrial, ventricular, and accessory pathway potential resolution.

Adult↗
PubMed1997

Decreased plasma glutamine level and CD4+ T cell number in response to 8 wk of anaerobic training.

The purpose of the present study was to investigate the role of plasma amino acids and glutathione (GSH) on the absolute number of leukocyte and lymphocyte subpopulations in response to different training programs. Healthy untrained subjects were randomly assigned to an 8-wk aerobic (AET) or anaerobic (ANT) exercise training program. Absolute number of cell counts did not significantly change in AET, whereas a decrease of CD4+ T cell counts (P < 0.05), a fall in cells expressing CD45RA+ antigen (P < 0.05), and a marked increase in CD8+ T cell numbers (P < 0.01) were noted in ANT at the end of the training period compared with baseline values. Furthermore, ANT demonstrated a marked rise (P < 0.001) in plasma glutamate from 27.6 +/- 2.8 to 49.8 +/- 5.2 microM and a considerable reduction (P < 0.001) of the plasma glutamine pool from 713 +/- 22 to 601 +/- 30 microM after 8 wk of training. The decrease in glutamine showed a strong positive correlation to the individual loss of CD4+ T cells (r = 0.67, P < 0.001). AET demonstrated a rise (P < 0.05) in GSH from 20.7 +/- 2.5 to 28.1 +/- 1.5 nmol/mg protein at terminal examination. In conclusion, our data indicate impairment of the number and activity of CD4+ T cells in response to 8 wk of ANT, which might be linked to metabolic factors such as glutamine.

Adult↗
PubMed1996

Analysis of neuro-behavioral Discovery data on the Macintosh computer.

This paper describes a suite of routines using IgorPro, a powerful analysis and graphing software package for the Macintosh computer, to enhance the ability to analyze, manipulate, and display data recorded with the Discovery acquisition software marketed by DataWave Technologies. The routines are able to time-align fast and slow data channels, and are especially useful for analyses that involve both neural and behavioral data. The software was designed for eyeblink conditioning and vocalization experiments, but it can easily be used for analyzing other types of neurobehavioral data. The data are first prepared on the PC with routines that inspect the header of the data file and translate the data file into a compact binary format that can be read by IgorPro. An option is also available to splice out data from unnecessary portions of an intertrial interval. The new file is then put on the Macintosh computer for display and analysis by IgorPro. These routines enable both neural and behavioral data to be quickly and easily reduced, manipulated, and statistically and graphically summarized.

Analysis of Variance↗
PubMed1996

Radiofrequency current catheter ablation of accessory atrioventricular pathways in Ebstein's anomaly.

BACKGROUND: In patients with Ebstein's anomaly, localization of accessory pathways (APs) may be impeded by abnormal local electrograms recorded along the atrialized right ventricle and by the presence of multiple APs. The impact of these factors on radiofrequency (RF) current catheter ablation of APs has not been evaluated yet. METHODS AND RESULTS: Twenty-one patients with Ebstein's anomaly and reentrant atrioventricular tachycardias underwent electrophysiological evaluation and subsequent attempts at RF catheter ablation. Thirty-four right-sided APs were found, with 30 located along the atrialized ventricle. Local electrograms in this region were normal in 10 patients but fragmented in 11. Fragmented electrograms prevented the clear distinction between atrial and ventricular activation potentials as well as the identification of AP potentials. Right coronary artery mapping was performed in 7 patients. Abolition of all 26 APs was achieved in the 10 patients with normal local electrograms and in 6 of 11 patients with abnormal electrograms. Right coronary artery mapping allowed AP localization and ablation in 5 patients. In the 5 patients with abnormal electrograms and a total of 8 APs, 6 APs could not be ablated. Unsuccessfully treated patients received antiarrhythmic drugs. During 22 +/- 12 months of follow-up, 5 patients had clinical recurrences, including 4 who had undergone a successful RF procedure. CONCLUSIONS: In patients with Ebstein's anomaly and reentrant atrioventricular tachycardias, factors likely to account for failure of RF catheter ablation include an AP located along the atrialized right ventricle and the abnormal morphology of endocardial activation potentials generated in this region.

Action Potentials↗
PubMed1996

Complementation of Ah receptor deficiency in hepatoma cells: negative feedback regulation and cell cycle control by the Ah receptor.

The Ah receptor (AhR) is a ligand-dependent transcription factor subunit that heterodimerizes with the AhR nuclear translocator (Arnt) and mediates the predominant biological effects of 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD). TCDD activates target genes in xenobiotica metabolism in many cell lines and, more specifically, delays G1-S progression of 5L hepatoma cells. Here we describe transient and stable AhR-expression analysis in AhR-deficient subclones of the TCDD-sensitive 5L cells. We tested the integrity of the AhR-signaling system beyond the lack of the receptor in the variant subclone and analyzed the role of AhR in cell cycle regulation. Transiently expressed AhR has a high basal activity on promoters containing AhR-binding sites, so-called XREs, when transfected into receptor-deficient variant cells compared to wild-type cells. Single- and double-hybrid analysis dissociates AhR ligand responsiveness, transactivation, and heterodimerization with Arnt from receptor binding to an XRE. Hybrid receptors also show the high basal activity in the absence of exogenous TCDD in AhR-deficient variant cells, indicating that the endogenous AhR-activating signal acts directly on the receptor rather than XRE-dependent promoters or DNA binding of the receptor. Stable expression of AhR in variant cell clones by retroviral infection fully reconstitutes TCDD responsiveness, including target-gene induction and delay of cell cycle progression. These AhR-reconstituted cells, like AhR-containing wild-type cells, show low basal activity of the transiently expressed AhR hybrid. Thus, the increased basal activity in AhR-deficient cells suggests a negative feedback control of AhR activity. In vitro ligand-binding assays are compatible with the idea that the increased basal activity is due to the accumulation of an AhR-binding endogenous ligand. In conclusion, AhR is causally responsible for TCDD-dependent cell cycle regulation and feedback control of AhR activity.

Animals↗
PubMed1996

Differences in the composition of chromaffin granules in adrenaline and noradrenaline containing cells of bovine adrenal medulla.

Several constituents of chromaffin granules were quantitatively determined in noradrenaline and adrenaline cells purified from bovine adrenal medulla. As far as secretory peptides are concerned noradrenaline granules contained slightly more secretogranin II, but much less chromogranin A than adrenaline granules. This can be explained by the dependence of the biosynthesis of chromogranin A on corticosteroids. Proteolytic processing of chromogranin A and secretogranin II was higher in noradrenaline cells which was paralleled by a higher content of the prohormone convertase PC2. Noradrenaline granules also contained a higher concentration of the vesicular monoamine transporter (vMAT2). No differences were found for dopamine beta-hydroxylase, prohormone convertase PC1, carboxypeptidase H and synaptophysin. These results indicate that the secretory cocktail of peptides released from these cells differs significantly between adrenaline and noradrenaline storing cells.

Adrenal Cortex Hormones↗
PubMed1996

Retrovirus-mediated transfer of the human O6-methylguanine-DNA methyltransferase gene into a murine hematopoietic stem cell line and resistance to the toxic effects of certain alkylating agents.

O6-Methylguanine-DNA methyltransferase (MGMT) is an important DNA repair protein that plays a key role in cancer chemotherapy by alkylating agents such as carmustine (BCNU) and Dacarbazine (DTIC). Therapy by BCNU and DTIC is reduced by dose-limiting hematological toxicity as a result of low MGMT repair activity in bone marrow cells. In this study, we have constructed a Moloney murine leukemia virus retroviral vector containing the human mgmt gene. High-titer retrovirus producer cells lines have been generated. Retroviral-mediated transfer of the human mgmt gene into murine multi-potent hematopoietic stem cells, FDCP-1, resulted in the expression of a high level of MGMT activity. In comparison with the control cells that were transduced with the parent vector, the MGMT-expressing clones were considerably more resistant to the cytotoxicity of the methylating agents, such as N-methyl-N'-nitro-N-nitrosoguanidine, N-nitroso-N-methyl-urea, and temozolomide, as well as the chloroethylating agents 1-(2-chloroethyl)-1-nitrosourea and BCNU. The protection provided by MGMT could be eliminated by the MGMT inactivator O6-benzylguanine. Thus, the principal lethal lesions produced by these alkylating agents in the murine hematopoietic stem cells and the MGMT deficiency in these cells can be complemented by retroviral-mediated gene transduction.

3T3 Cells↗
PubMed1996

[Preoperative risk assessment of children with Duchenne muscular dystrophy and relevance for anesthesia and intra- and postoperative course].

BACKGROUND: Patients suffering from muscle disorders have an elevated anesthetic risk, i.e. to develop malignant hyperthermia or rhabdomyolysis. In addition serious cardial and pulmonal complications are imminent during anesthesia for surgery. PATIENTS AND METHODS: We investigated retrospectively the preoperative risk factors of 81 Duchenne patients undergoing 101 anesthesia (79 for muscle releasement operations and 23 for spine surgery) and the relation to possible complications due to the anesthesia and the intra- and postoperative course. RESULTS AND DISCUSSION: 83% of the patients showed pathologic ECG, 26% cardiac insufficiency in echocardiography, 31% pathologic X-rays of the thorax and 73% serious pulmonary restriction. Consequently avoiding of anesthetic agents with a high trigger potential for developing malignant hyperthermia (i.e. halothane or muscle relaxants type succinylcholine) prevented severest complications as malignant hyperthermia, rhabdomyolysis or cardiac arrest. Nevertheless other complications (i.e. arrhythmia, cardiac insufficiency) occurred due to the cardiac and pulmonary limitations more pronounced in the older patients of the spine surgery group.

Anesthesia, General↗
PubMed1996

Activity of hippocampal pyramidal neurons during trace eyeblink conditioning.

The responsiveness of hippocampal pyramidal neurons was examined in young adult rabbits which were trained in a hippocampally dependent long interval trace eyeblink conditioning task. The majority of recorded cells were putative pyramidal neurons from area CA1. Our analysis indicates that 57% of 93 neurons had a statistically significant change in firing rate during some portion of the trial. The response patterns were quite heterogeneous, and inhibition was frequently observed. Inhibition was especially prominent in a post-trial period. Only a small percentage of the putative pyramidal cells exhibited robust changes in activity with prominent temporal modeling of the conditioned eyeblink response as previously described for rabbits trained with delay conditioning procedures (Berger et al. [1983] J Neurophysiol 50:1197-1219). These results were also similar for the CA3 pyramidal neurons that were recorded (N = 19). Few CA1 neurons had significant responses during unpaired presentations of tone and airpuff, and neural activity that was present was concentrated in the period commencing from airpuff onset. Preliminary data were also recorded from putative pyramidal neurons during hippocampally independent delay eyeblink conditioning, where a longer tone overlapped and coterminated with the airpuff. In this task five of 13 neurons (CA1 and CA3) were active during the trial period, another four were responsive only during the post-trial period, and other simultaneously recorded neurons were unresponsive. These data suggest a relatively more varied pattern of pyramidal neuron engagement during hippocampally dependent trace eyeblink conditioning than was apparent in previous multiple- and single-neuron analyses of activity during eyeblink conditioning.

Action Potentials↗
PubMed1996

Low plasma glutamine in combination with high glutamate levels indicate risk for loss of body cell mass in healthy individuals: the effect of N-acetyl-cysteine.

Skeletal muscle catabolism, low plasma glutamine, and high venous glutamate levels are common among patients with cancer or human immunodeficiency virus infection. In addition, a high glycolytic activity is commonly found in muscle tissue of cachectic cancer patients, suggesting insufficient mitochondrial energy metabolism. We therefore investigated (a) whether an "an-aerobic physical exercise" program causes similar changes in plasma amino acid levels, and (b) whether low plasma glutamine or high glutamate levels are risk factors for loss of body cell mass (BCM) in healthy human subjects, i.e., in the absence of a tumor or virus infection. Longitudinal measurements from healthy subjects over longer periods suggest that the age-related loss of BCM occur mainly during episodes with high venous glutamate levels, indicative of decreased muscular transport activity for glutamate. A significant increase in venous glutamate levels from 25 to about 40 microM was seen after a program of "anaerobic physical exercise." This was associated with changes in T lymphocyte numbers. Under these conditions persons with low baseline levels of plasma glutamine, arginine, and cystine levels also showed a loss of BCM. This loss of BCM was correlated not only with the amino acid levels at baseline examination, but also with an increase in plasma glutamine, arginine, and cystine levels during the observation period, suggesting that a loss of BCM in healthy individuals terminates itself by adjusting these amino acids to higher levels that stabilize BCM. To test a possible regulatory role of cysteine in this context we determined the effect of N-acetyl-cysteine on BCM in a group of subjects with relatively low glutamine levels. The placebo group of this study showed a loss of BCM and an increase in body fat, suggesting that body protein had been converted into other forms of chemical energy. The decrease in mean BCM/body fat ratios was prevented by N-acetyl-cysteine, indicating that cysteine indeed plays a regulatory role in the physiological control of BCM.

Acetylcysteine↗
PubMed1996

Ifosfamide, carboplatin and etoposide (ICE) combined with 41.8 degrees C whole body hyperthermia in patients with refractory sarcoma.

Two earlier studies resulted in the design of a phase II trial of 41.8 degrees C (x 60 min) extracorporeal whole body hyperthermia (WBH) with ICE, i.e. ifosfamide (5 g/m2), carboplatin (300 mg/m2), and etoposide given with WBH, as well as, day 2 and 3 post-WBH (100 mg/m2) for adult patients with refractory sarcoma. 12 patients entered this trial; all were evaluable. 8 patients had a history of prior chemotherapy associated with disease progression. Following WBH/ICE, 7 partial remissions were observed (58%); 3 patients experienced disease stabilisation; the aforementioned 10 patients each received four cycles of therapy. 2 patients exhibited progressive disease. Episodes of WHO graded (grade 3; grade 4) toxicity observed included: anaemia (2;2); leucopenia (5;7); thrombocytopenia (1;6); renal (0;1). Other toxicities (grade 1 and 2) included: anasarca, diarrhoea, ventricular arrhythmias, pressure sores, and perioral herpes simplex.

Adolescent↗
PubMed1996

Radiofrequency catheter ablation of left atrial tachycardia originating within the pulmonary vein in a patient with dextrocardia.

A case is presented of a 38-year-old male with dextrocardia in whom radiofrequency current ablation of an incessant atrial tachycardia originating within the infero-lateral pulmonary vein was achieved. Activation mapping with detection of the earliest atrial activation was used for identification of the arrhythmogenic focus. In addition to fluoroscopy, transesophageal echocardiography was used for catheter guidance during the transseptal puncture. The present experience suggests that location of an arrhythmogenic focus within the pulmonary venous system should be considered whenever early atrial activation during ectopic atrial tachycardia is recorded at the junction between the left atrium and the pulmonary veins.

Adult↗
PubMed1996

Magnetic resonance and single-photon emission tomography findings in a pair of twins discordant for Alzheimer's disease.

The value of functional and morphological neuroimaging in the early diagnosis of Alzheimer's disease (AD) is still debated. Described here are cerebral perfusion and linear measures of medial temporal lobe atrophy in 2 monozygotic twins discordant for AD who were investigated with technetium 99m-hexamethylpropy-leneamineoxime single-photon emission tomography (SPET) and magnetic resonance (MR) imaging. Both showed pathological cortical perfusion findings on SPET, while medical temporal lobe atrophy was present only in the affected twin. MR measures of medial temporal lobe atrophy have greater agreement with clinical data than do SPET measures of cerebral perfusion. Evaluation of atrophy may be useful in the early diagnosis of AD.

Activities of Daily Living↗