Search PubMed⌕ Search

Biomedical subjects

J Gross

Publications and source records attributed to J Gross.

At least 163 records · Page 9Linked to original sources
PubMed1991

HIV-1 proteinase is required for synthesis of pro-viral DNA.

HIV-1 proteinase activity is thought to occur primarily post-integration by cleaving the viral Gag and Gag-Pol polyproteins. Its role in the pre-integration stages of viral replication, however, has not been studied in detail. Here we report that a synthetic peptide analogue, UK-88,947, which is a specific inhibitor of purified HIV-1 proteinase, inhibits the processing of the viral polyproteins in cultures of HIV-1 infected cells and prevents the formation of mature, infectious virions. Analysis of DNA from HIV-1 infected cells treated with UK-88,947 showed that viral DNA synthesis was inhibited when the compound was added to cultures one hour before infection. Similar results were obtained when AZT was used. Neither HIV-1 reverse transcriptase or the replication of FIV are inhibited by UK-88,947.

Amino Acid Sequence↗
PubMed1991

Benefits of implantable defibrillators are overestimated by sudden death rates and better represented by the total arrhythmic death rate.

Benefits of the implantable defibrillator on survival were studied in 56 consecutive patients (concomitant coronary bypass or arrythmia surgery in 15) during an 8 year period between 1982 and 1990. During a follow-up period of 29 +/- 25 months, six patients had a sudden death and eight patients had a nonsudden cardiac death. Nonsudden cardiac deaths included three surgical deaths (death within 30 days after the surgery; two in patients without and one in a patient with concomitant cardiac surgery), one arrhythmia-related nonsudden death (death within 24 h after an arrhythmic event despite initial termination of the arrhythmia by the implantable defibrillators) and four nonarrhythmic cardiac deaths. The actuarial survival rate free of events at 1, 2 and 3 years was 96%, 96% and 92%, respectively, for sudden death, 91%, 91% and 87% for sudden death and surgical mortality and 89%, 89% and 85% for total arrhythmic death (sudden death, surgical mortality and arrhythmia-related nonsudden death). Thus, in patients treated with an implantable defibrillator, 1) the rate of sudden death is low (8% at 3 years); 2) 50% of nonsudden cardiac deaths are causally related to arrhythmia (surgical mortality or arrhythmia-related nonsudden death); 3) the total arrhythmic death rate is substantially higher than the sudden death rate; and 4) benefits of an implantable defibrillator are overestimated by reported sudden death and nonsudden cardiac death rates. The benefits may be better represented by the total arrhythmic death and nonarrhythmic cardiac death rates.

Actuarial Analysis↗
PubMed1991

Spatial variation of sequestered calcium in the multicellular stage of Dictyostelium discoideum as assayed by chlortetracycline fluorescence.

We have used chlortetracycline (CTC) as a fluorescent probe to detect the distribution of sequestered calcium in multicellular stages of Dictyostelium discoideum. Tips of late aggregates, slugs and early culminating masses fluoresce very strongly. Most of the fluorescence is intracellular in origin and emanates from a small number of intense punctate sources. The sources correspond in part to autophagic vacuoles vis. neutral-red staining, acidic digestive vesicles, and may also include intracellular organelles; cytoplasmic fluorescence is much weaker in comparison. The level of fluorescence drops in the middle portion of slugs and rises again in the posteriormost region, though not to as high a level as in the tip. This holds good irrespective of whether CTC is applied only in the neighbourhood of the aggregate centre, only in the aggregate periphery, or to the whole aggregate. We infer that there must be a good deal of mixing in the stages leading from aggregation to slug formation; thus the serial order in which cells enter an aggregate does not bear any relation to their ultimate fates. The other implication of our study is that calcium sequestration is much more extensive in prestalk and anterior-like cells than in prespore cells. These findings are discussed with regard to possible implications for pattern formation.

Animals↗
PubMed1991

Pacemaker infection with Mycobacterium avium complex.

A 21-year-old. HIV negative, malnourished, homeless woman with congenital heart block had a pacemaker implanted at 7 years of age and multiple procedures thereafter. The most recent of these procedures was replacement of a pulse generator in the right pectoral region. Four months later she had fever, pain, and swelling over the implant site resulting from infection with mixed flora and Mycobacterium avium complex. The pacemaker system was removed by thoracotomy via a median sternotomy and a new DDD pacemaker simultaneously implanted. She was treated with systemic antibiotics--isoniazid, rifampin, ethambutol--for 2 weeks. Six months later she was healthy, pacing well, and apparently free of infection, off all medications.

Adult↗
PubMed1991

Sudden death mortality in implantable cardioverter defibrillator patients.

Implantable cardioverter defibrillator (ICD) prevention of sudden cardiac death (SCD) is not absolute and our experience was reviewed to determine the frequency and nature of SCD in this population. The incidence and cause of mortality in 56 consecutive patients, who underwent ICD implantation beginning May 1982 with follow-up through May 19, 1990 were analyzed. Twenty-one patients died, 33% of the mortality was due to SCD, and 52% of deaths may be considered arrhythmic. The cumulative 1, 3, and 5 year SCD survivals were 93%, 89%, and 75%. All seven patients dying of SCD presented initially with SCD, all received previous shocks prior to SCD, and two of the seven patients had devices that were probably inactive at the time of death. We conclude that ICDs reduce but by no means eliminate arrhythmic death, particularly in those at highest risk for SCD. Arrhythmic death remained the most common cause of death in this population.

Arrhythmias, Cardiac↗
PubMed1991

Balb/C mice immunized with either xenogeneic or syngeneic TSH produce immunoglobulins with anti-TSH and thyroid-stimulating activities.

Balb/C mice were immunized with bTSH (xenogeneic TSH) or extracts of Balb/C pituitaries (containing syngeneic TSH), either intracutaneously with Freund's adjuvant or intrasplenically. After bTSH, all blood samples contained anti-TSH antibodies. Thyroid-stimulating activity was assayed on FRTL-5 cells. Of 80 sera from immunized mice, 33 induced an increase in 99mTcO4 uptake, and 31/79 induced an increase in thyroidal 3[H]thymidine uptake by thyrocytes. With syngeneic TSH, anti-TSH antibodies were found in 10/19 mice. Immunoglobulins increasing thyrocyte technetium uptake were found in 14/19 mice, and immunoglobulins that stimulated thymidine uptake in thyrocyte DNA were detected in 12/19 sera. After immunization with both types of TSH, sera of some mice showed only one of the two bioactivities. Hybridomas were prepared with splenic lymphocytes of the mice immunized with either of the TSH preparations. These secreted TSH-binding immunoglobulins or immunoglobulins which stimulated thymidine or technetium uptake by the thyrocytes. One of the hybridomas from mice immunized with pituitary extract secreted a monoclonal antibody which stimulated thyroidal thymidine uptake, but inhibited bTSH-induced 99mTcO4 uptake. These findings might suggest that the anti-idiotypic network acting on TSH as an antigen could be involved in the pathogenesis of stimulatory antibodies in thyroid disease.

Animals↗
PubMed1991

Morphology and phenotype of dendritic cells from peripheral blood and their productive and non-productive infection with human immunodeficiency virus type 1.

Immununoelectron microscopy of human peripheral blood mononuclear cells enriched for the presence of antigen-presenting dendritic cells (DC) has revealed two morphologically distinct cell types both expressing DR and DQ major histocompatibility complex (MHC) class II antigens but lacking T, B, natural killer (NK) and monocyte/macrophage markers. The first (type 1) has an irregular surface with numerous projections and shows cytoplasmic vacuoles. The second (type 2) has a paler nucleus showing only a thin rim of dense heterochromatin, large expanses of cytoplasm devoid of organelles, fewer vacuoles and a smooth cell boundary with few processes. In addition a few cells with a morphology similar to veiled cells of the afferent lymphatics (type 3 DC) were observed. Cells with a morphology intermediate between these three types were observed, suggesting that they may represent stages of the veiled cell differentiation pathway. Type 2 and 3 DC were shown by electron microscopy to be susceptible to productive infection with human immunodeficiency virus (HIV), whilst type 1 DC did not support virus growth. Examination of infected DC preparations by in situ hybridization revealed a higher number of DC positive for viral DNA and RNA than for RNA alone. Thus, in addition to productively infected DC, there may be some that are latently infected, contain defective virus genome or replicate virus at a very low level.

Acquired Immunodeficiency Syndrome↗
PubMed1991

[The value of 31 P nuclear magnetic resonance spectroscopy in follow up of Fontaine stage IIb peripheral arterial occlusive disease].

The method of nuclear magnetic resonance (NMR) spectroscopy compared to the parameters absolute-, pain-free walking distance and ankle/arm coefficient in Doppler pressure was used for observation of patients with peripheral arterial occlusive disease stage IIb according to Fontaine. While the classic parameters (walking distances, ankle/arm coefficient) described a homogenous group, NMR-spectroscopy parameters showed marked inter- and intraindividual variations during exercise. Further studies on high magnetic power fields, exercise patterns and muscle recreation analysis have to be carried out to develop a reliable system of non invasive muscle energy monitoring in vascular diseases.

Aged↗
PubMed1991

Kinetic evidence that the sodium-dependent high-affinity and the sodium-independent low-affinity dopamine uptake are mediated by one carrier.

In synaptosomes of the rat striatum the dopamine uptake was measured in a concentration range of 0.03 microM to 100 microM. In the presence of sodium the uptake exhibited a non-Michaelis-Menten kinetics and in a sodium-free medium the uptake kinetics was sigmoid. According to these findings a novel model for the dopamine uptake is proposed. Its main assumption is one carrier with two dopamine binding sites.

Animals↗
PubMed1991

[Comparative material studies on dental stones in accordance with DIN 13911].

It was the object of this investigation to compare nine high-strength stone plasters in terms of visual appearance, pouring time, setting time, setting expansion, compressive strength and detail reproduction in accordance with DIN 13911 and ISO 6873 using both standard consistency as indicated in the industrial standard and the water-to-powder ratio as indicated by the manufacturer. None of the tested stones met the visual requirements in all points. Regarding their physical properties, six tested stones were up to standard. Three stones failed to meet the DIN and ISO requirements. Following the manufacturer's mixing instructions resulted in a significant improvement in material properties as against standard consistency. Disregarding some minor improvements required, DIN 13911 and ISO 6873 are useful standards for a standardized comparison of dental plasters.

Calcium Sulfate↗
PubMed1991

Uptake of lysine and incorporation into proteins of the cortex during a short-term hypoxia of neonatal rats.

The uptake of [14C]lysine and its incorporation into proteins of the brain cortex was determined in vivo during a mild hypoxia (pO2 = 10.5-11.0 kPa) for short times up to 120 min in newborn rats. The uptake was relatively high within the first 15 min and was not altered by hypoxia. A diminished incorporation of lysine by about 20% was measured in the early phase of hypoxia. Later on the incorporation of the radioactive amino acid increased and reached control values. All investigated subcellular fractions (nuclei, mitochondria, synaptic membranes, and 9000 x g supernatant) showed in this respect similar sensitivities to hypoxia as indicated by the amount of protein-bound [14C]lysine in these fractions.

Animals↗
PubMed1990

Role of (+-)-1,2-bis(3,5-dioxopiperazinyl-1-yl)propane (ICRF-187) in modulating free radical scavenging enzymes in doxorubicin-induced cardiomyopathy.

This study was designed to investigate the mechanism by which (+-)-1,2-bis(3,5-dioxopiperazinyl-1-yl)propane (ICRF-187) protects against doxorubicin cardiotoxicity. Others have hypothesized that the major factor contributing to doxorubicin cardiotoxicity is the depletion of the antioxidant defense mechanisms of the heart induced by doxorubicin. Mice were acutely (24-h exposure) or chronically (13-week exposure) treated with doxorubicin to develop a model for cardiotoxicity. Five-week-old BALB/c mice were given i.p. injections of doxorubicin alone or 30 min after ICRF-187, while control mice received ICRF-187 or 0.9% NaCl solution alone without doxorubicin. Electron microscopy of the mouse hearts demonstrated conclusively that doxorubicin was cardiotoxic after 13 weeks of exposure, showing mitochondrial degeneration and disruption of the myofibrillar organization. Furthermore, normal morphology of the electron micrographs after treatment with doxorubicin and ICRF-187 indicated that ICRF-187 was cardioprotective. The activities of the antioxidants superoxide dismutase, glutathione peroxidase, and catalase and the concentration of reduced glutathione were measured in the heart, liver, kidneys, and skeletal muscle of mice treated with doxorubicin, ICRF-187, or the drug combination. After acute or chronic exposure to the drugs there was no significant difference in enzyme or reduced glutathione levels compared to the control mice in any of the treatment groups. It was concluded that neither the cardioprotective effect of ICRF-187 nor the cardiotoxicity induced by doxorubicin was related to an effect on cardiac antioxidants, but rather another mechanism operated in this particular model.

Animals↗
PubMed1990

[Assessment of diabetic autonomic neuropathy by heart rate monitoring].

Assessment of diabetic autonomic neuropathy in a representative sample of 91 noninsulin-dependent diabetics was performed in 3 community clinics. A difference of less than 10 beats/min in heart rate between deep inspiration and deep expiration determined by ECG recording served as the criterion for autonomic neuropathy. By this test, 86% of the patients had diabetic autonomic neuropathy, a slightly higher proportion than that reported by others using similar criteria in more selected populations. The test is very sensitive and can be used for screening.

Adult↗
PubMed1990

Structural analysis of bovine pancreatic thread protein.

Pancreatic thread protein (PTP) forms double helical threads in the neutral pH range after purification, undergoing freely reversible, pH-dependent globule-fibril transformation. The purified bovine PTP consists on SDS gels of two carbohydrate-free polypeptide chains (Gross et al., 1985). Plasma desorption mass spectrometry and amino acid sequence analysis now confirm that bovine PTP contains two disulfide-bonded polypeptides, an A chain of 101 amino acid residues with a molecular weight of 11,073 and a B chain of 35 residues with a molecular weight of 3970. The intact protein exhibits a molecular weight of 15,036, agreeing greater than 99.9% with the molecular weight calculated from the sequence. The B chain sequence was determined by gas-phase Edman degradation of the intact polypeptide. The A chain sequence was determined from overlapping peptides generated by cleavage at lysyl, tryptophanyl, and aspartyl-prolyl residues. Based upon the bovine PTP cDNA structure, the two chains of the protein result from cleavage of a single polypeptide with removal of a dipeptide between the NH2-terminal A chain and COOH-terminal B chain. Comparison of bovine PTP with other proteins reveals significant structural relatedness with the single-chain homologues from human and rat pancreas and with the motif associated with Ca2(+)-dependent carbohydrate recognition domains. The physiological role of PTP has not yet been resolved. The protein is present in very high concentration in pancreatic secretion and it has been detected in brain lesions in Alzheimer's disease and Down syndrome and in regenerating rat pancreatic islets. The present results provide a firm protein base for ongoing molecular, physical-chemical, and structure-function studies of this unusual protein.

Amino Acid Sequence↗