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Biomedical subjects

B Feldman

Publications and source records attributed to B Feldman.

At least 19 recordsLinked to original sources
PubMed1992

Frequency of late potentials on signal-averaged electrocardiograms during thallium stress testing in coronary artery disease.

Late potentials detected by signal-averaged electrocardiography (SAECG) are an important noninvasive indicator identifying patients with previous myocardial infarction at risk for developing ventricular tachycardia. The role of myocardial ischemia in the development of late potentials is undefined. This study attempts to determine if late potentials on SAECG can be produced during scintigraphically proven ischemia. A signal-averaged electrocardiogram was obtained before and immediately after single-photon emission computed tomography thallium exercise testing in 51 patients. Reversible ischemia was documented in 25 cases with no significant changes in the parameters of SAECG; patients with previous myocardial infarction (n = 10) also had no significant changes from baseline. Multivariate analysis with respect to reversible ischemia and previous myocardial infarction was unrevealing. Patients with late potentials at baseline (n = 10) who developed reversible ischemia (n = 5) had a shorter QRS duration than those with late potentials at baseline and no reversible ischemia. The data indicate that exercise-induced scintigraphically proven ischemia does not alter SAECG even in the presence of previous myocardial infarction. Patients with late potentials at baseline may actually have a shortened QRS duration during reversible ischemia as opposed to the expected lengthening of the QRS.

Coronary Disease↗
PubMed1991

Monoclonal antibody mapping of structural and functional plectin epitopes.

To map structural and functional epitopes of the cytomatrix protein plectin, a set of mAbs was prepared by immunization of mice. Using immunoblot analysis of plectin fragments obtained after limited digestion with various proteases, two groups of mAbs were distinguished. The epitopes of one group (1) were located on a 130-kD terminal segment of the plectin 300-kD polypeptide chain, whereas those of the other group (2) bound within a 40kD segment confined to a central domain of the polypeptide chain. Domains containing the epitopes of group 2 mAbs were shown to include in vitro phosphorylation sites for kinase A, whereas kinase C phosphorylation sites were found on the same terminal segment that contained group 1 mAb epitopes. Rotary shadowing EM of mAb (Fab fragment) -decorated plectin molecules at various states of aggregation, ranging from characteristic dumbbell-shaped single molecules to highly complex multimeric structures, revealed that the epitopes of group 1 as well as those of group 2 mAbs were located on plectin's roughly 200-nm long rod domain interlinking its two globular end domains. Epitopes of group 1 mAbs were localized within a region near the center of the rod, those of group 2 in more peripheral sections near the globular end domains. Solid-phase binding assays carried out in the presence of Fab fragments of mAbs demonstrated an interference of certain group 1 mAbs in the interactions of plectin with vimentin and lamin B. On the other hand, plectin's self-interaction was inhibited mainly by Fab fragments with epitopes in the peripheral rod domain (group 2 mAbs). Together, these results suggested that the molecular binding sites of plectin for vimentin and lamin B, as well as the phosphorylation sites for kinase C, were confined to a defined central section of plectin's rod domain. In addition, they suggest an involvement of peripheral rod sections in plectin self-association.

Animals↗
PubMed1991

Reduction of neonatal mortality after multiple doses of bovine surfactant in low birth weight neonates with respiratory distress syndrome.

To determine if outcomes of low birth weight neonates with respiratory distress syndrome can be improved by the administration of multiple doses of bovine surfactant, we conducted two identical multicenter, controlled trials, and the results were combined for analysis. Seven hundred and ninety-eight neonates weighing 600 to 1750 g at birth who had developed respiratory distress syndrome within 6 hours of birth were assigned randomly to receive either 100 mg of phospholipid/kg of Survanta, a modified bovine surfactant (n = 402), or a sham dosing procedure (n = 396). Neonates whose respiratory distress persisted could be given up to three more doses, with all doses to be given in the first 48 hours after birth. Dosing was performed by investigators not involved in the clinical care of the neonates; nursery staff were kept blinded as to the treatment assignment. Fewer Survanta-treated neonates died of any cause (18.4% vs 27.3%, P = .002), died of respiratory distress syndrome (9.0% vs 20.3%, P less than .001), and either died or developed bronchopulmonary dysplasia due to respiratory distress syndrome (51.2% vs 64.6%, P less than .001). Neonates who received Survanta also had greater improvement in their oxygenation and ventilatory status from baseline to 72 hours than did control neonates. Survanta-treated neonates were at lowered risk for developing pulmonary interstitial emphysema (18.6% vs 39.3%, P less than .001) and other pulmonary air leaks (11.5% vs 25.9%, P less than .001). We conclude that multiple doses of Survanta given after diagnosis of respiratory distress syndrome reduce mortality and morbidity.

Administration, Inhalation↗
PubMed1989

The Utah anesthesia workstation.

A prototype anesthesia workstation has been developed to demonstrate the feasibility of a computer-assisted anesthesia workplace. The workstation provides a central display of information and aids the user in controlling and monitoring the anesthesia delivery system. The anesthesiologist interacts with the workstation through a Macintosh computer, which is easy for the clinician to understand and to use. Seventeen sensors and monitors transmit information from the anesthesia delivery system to the computer. The computer monitors this information using a set of rules, evaluated once each breath, to detect changes in the delivery system. If an event is detected, the computer alerts the anesthesiologist with a diagram, a text message, and an audible warning. A laboratory test of the monitoring system was performed to see if it properly identified 26 different critical events during simulated low flow and closed circuit anesthesia. Five hundred and eight-three of 660 simulated critical events (88%) were identified with the unique and correct message. On 35 occasions, multiple messages were displayed, including the correct one. Critical events were misidentified or not detected 42 times. Eight false positive alarms occurred during the 20 h of testing; all occurred as a result of baseline drift in a single transducer. These results demonstrate that a sophisticated monitoring system can reliably diagnose specific anesthesia machine failures.

Anesthesiology↗
PubMed1989

Anti-tumor immunity in breast cancer evaluated by a computerized tube leukocyte adherence inhibition (LAI) assay.

Seventy-four women admitted for breast biopsy were monitored before surgery for anti-tumor cell-mediated immunity using a computerized tube leukocyte adherence inhibition (LAI) assay. Spent medium from breast, lung and colon adenocarcinoma cell lines was used as the source of organ-specific neoantigens for standardization of the assay. Peripheral blood leukocytes from 25/40 (62.5%) patients diagnosed after surgery as breast cancer responded to spent medium with a positive non-adherence index (NAI). A positive NAI was inversely related to tumor mass because only 7/18 (38.8%) of those with Stage III or IV had a positive NAI; while 18/22 (81.8%) of those with Stage I or II were positive. Cross-reactive antigenicity was not observed when spent medium from breast cancer was incubated with leukocytes from patients with several other solid tumors nor when leukocytes from breast cancer patients were incubated with spent medium from lung or colon carcinoma cell lines. The antigenic material in the spent medium appears to be an organ-specific neoantigen because only 1/34 patients with benign breast disease had a positive NAI and all normal healthy control individuals were negative. The results of this study show that spent medium of a breast carcinoma cell line is more reliable than crude cancer extracts for use in LAI to detect specific anti-tumor cellular immune responses. The improved method presented in this report can be a useful tool in the early diagnosis of breast cancer and for monitoring of patients with this disease.

Adult↗
PubMed1987

Estrogen and progesterone receptor levels are lower in specimens taken from previously biopsied breast tumor tissue.

Estrogen and progesterone receptor (ER and PgR) levels and peroxidase activity were measured in the first biopsy and in tissue removed 4-10 days later during mastectomy of previously biopsied tumor. The proportion of ER- and PgR-positive tumors declined from 71% and 63%, respectively, in the biopsy group, to 46% and 36% in the mastectomy group. Peroxidase activity was low or absent in all biopsy specimens, but was present in 16 out of 25 tumors which had been biopsied previously. Receptor levels in paired specimens obtained from the same patient were lower in the mastectomy in 14 out of 18 receptor-positive cases. This decrease in the receptor level was accompanied by a significant increase in peroxidase activity. We suggest that an attempt be made to perform receptor analysis from "virgin" tumor tissues at initial biopsy. If this is not possible, measurement of peroxidase activity could be helpful in evaluating the degree of receptor deterioration.

Biopsy↗
PubMed1986

Psychoactive drug use among practicing physicians and medical students.

We surveyed random samples of 500 practicing physicians and 504 medical students in a New England state during 1984-1985; 70 percent of the physicians and 79 percent of the students responded. Fifty-nine percent of the physicians and 78 percent of the students reported that they had used psychoactive drugs at some time in their lives. In both groups, recreational use most often involved marijuana and cocaine, and self-treatment most often involved tranquilizers and opiates. In the previous year, 25 percent of the physicians had treated themselves with a psychoactive drug, and 10 percent had used one recreationally. Although most of the use was experimental or infrequent, 10 percent of the physicians reported current regular drug use (once a month or more often) and 3 percent had histories of drug dependence. More physicians and medical students had used psychoactive drugs at some time than had comparable samples of pharmacists and pharmacy students. The results suggest a need for renewed professional education about the risks of drug misuse.

Cannabis↗
PubMed1986

Angiographic recognition of ostial left main coronary artery stenosis: case report.

Ostial left main coronary stenosis has a poor prognosis and increased mortality rate with coronary arteriography. Due to its anatomic location, visualization of the stenosis may be difficult. A high index of suspicion based upon only a few signs should prompt the physician to perform certain maneuvers to obtain the correct diagnosis. Four illustrative cases are presented and discussed.

Aged↗
PubMed1984

Effect of dextran and aspirin on platelet adherence after transluminal angioplasty of normal canine coronary arteries.

The effect of low-molecular-weight dextran and aspirin on platelet deposition after transluminal coronary angioplasty was studied in a normal canine model. Eighteen anesthetized, open-chest dogs were separated into 4 groups. All dogs received 3,000 units of intravenous heparin 10 to 20 minutes before the procedure. Dogs in Group 1 served as controls and were given no further treatment. Dogs in Group 2 received low-molecular-weight dextran by continuous intravenous infusion at a rate of 20 ml/hour for 1 hour before balloon inflation. Dogs in Group 3 were given 500 ml of low-molecular-weight dextran as an intravenous bolus over 1 hour, beginning 4 hours before the procedure. Dogs in Group 4 were fed 20 mg/kg of aspirin 3 hours before angioplasty. The dogs were killed 10 minutes after angioplasty and the arterial segments subjected to balloon inflation submitted for electron microscopic analysis. An additional group of 10 dogs was used to assess the bleeding times and platelet counts from control and drug-treated dogs. Drug treatment was associated with significant prolongation of the bleeding time and reduction in platelet number. Extensive endothelial desquamation in the area of balloon angioplasty was observed in all dogs. However, no appreciable qualitative difference in either the degree or extent of rapid platelet deposition to the exposed subendothelium was discernible between the control and any of the treatment groups. These results do not confirm previous observations with low-molecular-weight dextran. Further work on the initial and long-term platelet response after endothelial injury should be undertaken in a primate atherosclerotic model.

Angioplasty, Balloon↗
PubMed1984

cAMP-independent protein kinase activity is correlated with growth of rat mammary tumors.

An important portion of the protein kinase activity in the 7,12-dimethylbenz(a)anthracene (DMBA) induced rat mammary tumour is inhibited by the bioflavonoid quercetin (10(-4) M). By partial purification on a DEAE Cellulose column it was shown that the quercetin-inhibitable enzyme activity can be eluted in a separate peak which contains markedly reduced cAMP-dependent protein kinase activity. Since quercetin does not affect the cAMP-dependent protein kinase activity, this drug becomes a potent tool for the quantitation of this special activity in the tumor. By hormonal manipulation, namely ovariectomy and estrogen treatment, it was shown that changes in the growth rate of the tumour were closely correlated with the magnitude of these special protein kinase activities. These results suggest a possible cause-and-effect relationship between cyclic AMP-independent protein kinase activity and tumour malignancy in this chemically induced tumor. These data are similar to recent findings in viral-induced malignant transformation.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1984

Production of mucous glycoproteins by nasal turbinates in vitro.

An in vitro system of human nasal turbinate tissue culture has been developed. Nasal turbinate tissue resected during surgery for nasal obstruction is dissected free of bone, placed on absorbable gelatin sponges, and cultured with CMRL-1066 medium containing antibiotics. Viability of explants may be demonstrated both physiologically and histologically through a period of 4 weeks. 3H-glucosamine added to the medium is biosynthetically incorporated into mucous glycoprotein (MGP). Gel filtration column chromatography on Sephacryl S-1000 in 6M urea in 0.005M phosphate buffer demonstrates human turbinate MGP to fractionate with 85% of the radiolabel filtered and 15% excluded by the column. The excluded MGP fractionates with globular proteins of greater than 20 X 10(6) daltons, while the fractions that enter the column filter with molecular sizes of 0.4 X 10(6) to 20 X 10(6) daltons. MGP synthesized by human lung airways has comparable sizing characteristics, suggesting a similarity in upper and lower airway mucus chemistry.

Culture Techniques↗
PubMed1984

Protein kinase activity in the rat mammary gland during pregnancy, lactation, and weaning: a correlation with growth but not with progesterone receptor levels.

A protein kinase activity fraction was defined in cytosols and membranes of mammary tissue isolated from rats during pregnancy lactation, and weaning. By partial purification on DEAE-cellulose columns, it was shown that this protein kinase activity is cAMP independent and that its preferential substrate is casein and not histone. This protein kinase activity is inhibited by the bioflavonoid quercetin at doses that do not inhibit cAMP-dependent protein kinase activity. The enzyme requires Mg2+ and is inactive in the presence of 10 mM Ca+2; these properties distinguish this activity from casein kinase activity found in the Golgi fraction and involved in milk protein processing. By following the physiological cycle of mammary gland development during pregnancy, lactation, and weaning, we found a close correlation between proliferation, expressed as the DNA content per gland, and quercetin-inhibited cytosolic protein kinase activity. Moreover, changes in this phosphorylating activity preceded the glandular growth changes. There was a less significant correlation between the growth process and protein kinase activity in the membrane fraction. The cytosolic cAMP-dependent protein kinase activity showed (only partial) correlation with growth only during pregnancy. Cytosolic progesterone receptor levels in mammary tissue were used as an estrogenic marker. Tissue growth correlated with progesterone receptor levels during pregnancy, where estrogens are the predominant hormones affecting tissue proliferation. However, no such correlation was found during lactation and weaning, when PRL is the major hormone affecting mammary gland growth. These results suggest that quercetin-inhibitable protein kinase activity is not merely another estrogenic marker, but represents more general regulatory activity which might be connected to growth processes of breast tissue.

Animals↗
PubMed1984

Cyclic changes in rat uterine proliferation during the estrous cycle are preceded by changes in protein kinase activity.

A protein kinase activity was defined in cytosols and membranes of rat uterus by using two types of enzyme inhibitors. The heat stable protein kinase inhibitor inhibited the cAMP-stimulated protein kinase but not the basal activity measured in the absence of the cyclic nucleotide. However, this basal activity was inhibited by quercetin in a dose-dependent manner, whereas the cAMP-stimulated protein kinase was not inhibited by this bioflavonoid. Thus, quercetin can be used as a tool to define a specific fraction of cAMP-independent protein kinase activity in rat uterine cytosols and membranes. The mature rat uterus is characterized by short (4 days) cyclic changes in tissue growth. Cell proliferation expressed as total uterine DNA content is observed on proestrus, reaches its peak at estrus, and declines sharply during metestrus and diestrus. The quercetin-inhibited protein kinase activity in the membranes of this tissue also changes cyclically and precedes by one phase the cyclic change in tissue proliferation. The clearest effect was seen when the protein substrates for this protein kinase activity were endogenous membrane proteins partially solubilized by Triton X-100 treatment. In contrast no change was observed in cytosolic, quercetin-inhibited protein kinase activity. The cAMP-stimulated protein kinase activity decreased slightly on diestrus. These results support our working hypothesis that tissue proliferation in the uterus and other tissues such as rat mammary gland and mammary tumors, correlates with cAMP-independent, quercetin-inhibited, protein kinase activity in these tissues.

Animals↗