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Biomedical subjects

R J Pietras

Publications and source records attributed to R J Pietras.

At least 37 records · Page 2Linked to original sources
PubMed1983

Chronic recurrent right ventricular tachycardia in patients without ischemic heart disease: clinical, hemodynamic, and angiographic findings.

Surgical cure of right ventricular tachycardia (RVT) has been recently described in patients with "arrhythmogenic right ventricular dysplasia," a disease characterized by abnormal electrical activation of the right ventricle and localized or generalized angiographic right ventricular (RV) wall motion abnormalities (WMA). In search of a selective RV cardiomyopathy complicated by chronic recurrent RVT, 38 consecutive patients (mean age 30.5 +/- 12 years) with RVT and no ischemic heart disease were studied clinically, noninvasively, and by cardiac catheterization including left and right ventriculography. RV volumes were as follow: end-systolic volume ranged from 23 to 103 (mean +/- SD, 45.8 +/- 20) cc/m2 and was abnormal in 14 patients (37%); end-diastolic volume ranged from 57 to 138 (90.5 +/- 26) cc/m2 and was abnormal in 15 patients (39%); ejection fraction (EF) ranged from 0.18 to 0.64 and was decreased in five patients (13%). Seventeen patients (45%) had abnormal RV volume, EF, and/or pressures (RVD), five (13%) of whom had abnormal LV volume, EF, and/or pressures (LVD), and 12 (32%) patients with RVD had no LVD. Twenty-one patients (55%) had no RVD, two of whom had LVD. Only two of the 17 patients had RV regional WMA, one with and one without LVD. Most patients with LVD five of seven (71%) also had RVD while 12 of 31 patients (39%) with no LVD had RVD. In conclusion, less than one half of patients with RVT had selective RV cardiomyopathy and more than one half of patients with RVT had normal RV hemodynamics and angiography.

Adolescent↗
PubMed1981

Lysosomal cathepsin B-like activity: mobilization in prereplicative and neoplastic epithelial cells.

Extracellular release of acid thiol proteinase activity by prereplicative and neoplastic epithelial cells was studied in serum-free, chemically defined media (CDM) in vitro. Cells isolated from urinary bladder of male bullfrogs and endometrium of ovariectomized rats each showed preferential secretion of cathepsin B-like (CB) activity within 30 min after exposure to carcinogenic nitrosamines (5 X 10(-4) M) or to mitogenic estrogen 1 X 10(-9) M), respectively. In contrast, release of such proteinase, and stimulation of cell proliferation were far less extensive in rat preputial gland cells treated with estradiol-17 beta. Striking secretion of CB was characteristic of neoplastic, but not noncancerous, epithelial cells from human ectocervix. Neoplastic cells with divergent rates of cell-to-cell aggregation were separated by a filtration method. Those cells with high rates of intercellular aggregation also exhibited higher rates of cell proliferation in CDM, as well as in soft gels, and a greater level of CB release than corresponding cancer cells with a relatively low degree of intercellular adhesion. Brief treatment of neoplastic cervical epithelial cells with liposomes containing entrapped leupeptin, a potent inhibitor of CB activity, elicited a sharp reduction in both cellular thiol proteinase activity and cell growth as compared to appropriate controls. These data indicate that mobilization of lysosomal CB activity in prereplicative and malignant cells may play a significant role in the promotion of cell proliferation.

Animals↗
PubMed1980

Partial purification and characterization of oestrogen receptors in subfractions of hepatocyte plasma membranes.

To assess the subcellular distribution of oestrogen-binding components in their native state, plasma membrane and other cell fractions were prepared from hepatocytes in the absence of [(3)H]oestradiol-17beta. Cells from livers of ovariectomized rats were disrupted, with submaximal homogenization in buffered isotonic sucrose with CaCl(2) and proteinase inhibitor, and fractionated by using isotonic media. Fractions were characterized by determinations of enzyme activities, biochemical constituents and ligand binding. Specific binding of 2nm-[(3)H]oestradiol-17beta to intact cells and their fractions was detemined after equilibration for 1.5h at 4 degrees C. More than 92% of the radioactivity from representative preparations was verified as authentic oestradiol by thin-layer chromatography. Activities of plasma-membrane marker enzymes as well as binding sites for oestrogen and for wheat germ agglutinin were present principally in particulate fractions, rather than in 105000g-supernatant fractions. However, by using alternative homogenization procedures (i.e. hypotonic media), known to fragment and strip structural components, oestradiol-binding sites and activities of plasma-membrane marker enzymes were distributed predominantly into cytosol. By using the more conservative procedures, plasma membranes of low (rho=1.13-1.16) and high (rho=1.16-1.18) density were purified from crude nuclear fractions. A second low-density subfraction of plasma membrane was prepared from microsome-rich fractions. Activities of plasma-membrane marker enzymes were enriched to about 28 and four times that of the homogenate in plasma membranes of low and high density respectively. Binding sites for wheat germ agglutinin and oestradiol were concentrated in low-density plasma membranes to 46-63 times that of the homogenate. Specific binding of oestrogen in low-density plasma membranes purified from crude nuclei was saturable, with an apparent association constant of 3.5nm. At saturation, such oestradiol receptors corresponded to 526fmol/mg of membrane protein. A Hill plot showed a moderate degree of positive co-operativity in the interaction of hormone with plasma membranes. Specific binding of [(3)H]oestradiol-17beta was reduced by a 200-fold molar excess of unlabelled oestradiol-17beta, oestriol or diethylstilbestrol, but not by oestradiol-17alpha, cortisol, testosterone or progesterone. Binding was also blocked by prior exposure of membranes to trypsin or to 60 degrees C, but remained essentially undiminished by extraction of membranes with either hypotonic or high-salt buffers. Extraction with 0.1% (v/v) Triton X-100 partially solubilized the oestrogen-binding component(s) of plasma membranes. Particle-free extracts were resolved on 5-20% (w/v) sucrose density gradients with either 0.01m- or 0.4m-KCl, and the fractions were analysed by adsorption to hydroxyapatite. In low-salt gradients macromolecule-bound oestrogen sedimented at predominantly 7.4S and binding was 1560 times that of the homogenate. Under high-salt conditions oestradiol-binding activity occurred at both 3.6S and 4.9S.

Animals↗
PubMed1979

Estrogen-induced membrane alterations and growth associated with proteinase activity in endometrial cells.

Endometrial cells isolated from uteri of ovariectomized rats were treated in vitro with 1 X 10(-9) M estradiol-17 beta (E2beta) to analyze early changes in membrane properties during hormone-induced growth. After 30-min exposure to E2beta at 22 degrees C, cells exhibited an enhanced capacity to bind erythrocytes (hemadsorption) in the presence of concanavalin A (Con A) to 237% of the level in paired controls. Fluorescence microscopy revealted that approximately 25% of cells exposed to E2beta, but not estradiol-17 alpha (E2alpha), showed a redistribution into polar clusters of Con A-binding sites that were dispersed in random patches at the external surfaces of control cells. These hormore-induced membrane alterations were abolished by prior treatment of cells with inhibitors of thiol proteinase activity of the cathepsin B1 (CB1) type, such as leupeptin and iodoacetate. Leupeptin at 4.5 X 10(-7) M also reduced the affinity of [3H]E2beta binding to intact cells but did not influence specific binding of the hormone to macromolecular components of cytosol. A pronounced increase in the availability of endogenous CB1, But not of alkaline phosphatase, succinate, or lactate dehydrogenase, in the extracellular media was elicited within 30 min after E2beta treatment. In cells cultured in chemically defined medium for up to 48 h, E2beta, but not E2alpha, enhanced cell proliferation and stimulated [3H]thymidine incorporation into macromolecular form. These E2beta-induced effects were abolished by prior treatment of cells with liposome-entrapped leupeptin at a final concentration of 7 X 10(-8) M. The net rate of intercellular adhesion among endometrial cells was also enhanced by E2beta. This hormonal response was diminished by prior exposure to leupeptin. Fractionation of cells by selection for adhesiveness due to E2beta exposure for 30 min yielded a subpopulation of rapidly dividing cells which surpassed their less adhesive counterparts in cathepsin secretion and in Con A-mediated hemadsorption. These results indicate that leupeptin-sensitive proteinase activity may contribute to membrane and growth modifications elicited by E2beta treatment in endometrial cells.

Animals↗
PubMed1978

A characteristic precordial repolarization abnormality with intermittent left bundle-branch block.

We reviewed electrocardiograms of 23 patients with intermittent left bundle-branch block. A characteristic electrocardiographic pattern consisting of right and mid-precordial deep symmetrical T-wave inversions was detected during normal conduction in 19 of the 23. Of the seven patients who had cardiac catheterization, only two had findings suggestive or organic heart disease and only one had significant obstructive coronary disease. Thus we conclude that patients with intermittent left bundle-branch block frequently have T-wave inversions in right and mid-precordial leads during normal conduction that do not necessarily reflect coronary disease. These T-wave changes are similar to those after termination of chronic right ventricular pacing (left bundle-branch pattern), suggesting that both patterns of abnormal ventricular activation can produce abnormal repolarization when activation returns to normal.

Adult↗
PubMed1978

Elevated serum cathepsin B1 and vaginal pathology after prenatal DES exposure.

Activities of the lysosomal enzymes, cathepsin B1 (CBI), beta-glucuronidase, and beta-N-acetyl-D-glucosaminidase, as well as sialyl transferase, alkaline phosphatase, and placenta-like alkaline phosphatase, were determined on blind-coded serums from 99 women exposed to diethylstilbestrol (DES) in utero and 40 unexposed subjects of comparable age range. Cathepsin B1 averaged 100%, 1040% (P less than 0.001), 2720 % (P less than 0.001), and 4760% (P less than 0.001) of controls in DES-exposed women with no genital tract abnormalities (N = 11), adenosis (N = 68), adenosis with concomitant dysplasia (N = 15), and clear-cell adenocarcinoma (N = 5), respectively. The later two groups also exhibited 0.01). Activities of the other four enzymes in serums of DES-exposed women were unchanged from those controls, suggesting that alterations in CBI were not due to generalized increases in lysosomal membrane instability or other gross cellular damage. In 2 DES-exposed women with clear-cell adenocardinoma, from whom serial samples were available, preoperative levels of serum CBl fell from a mean of 4280% to values indistinguishable from controls by 7--12 days after tumor excision, concurrently with objective signs of remission. Recrudescence of serum CBI levels preceded by at least 3 months clinical evidence of persistent adenosis accompanied by vaginal dysplasia. Although the nature of the increments in CBI-like activity in the majority of subjects with DES-related pathology remains to be determined, the findings may complement present methods of physical diagnosis and prognosis.

Acetylglucosaminidase↗
PubMed1977

Sites of conduction disease in aortic stenosis: significance of valve gradient and calcification.

Electrophysiologic studies were done in 32 patients with aortic stenosis. In 24 patients with intact A-V conduction, A-H intervals ranged from 55 to 145 msec and were prolonged in two. Two had split His bundle potentials. The H-V intervals ranged from 25 to 94 msec and were prolonged in 12. The mean H-V interval was 63 +/- 2.6 msec in 12 patients with calcific aortic stenosis compared with 50 +/- 4.9 msec in 12 without calcification (P less than 0.05). The mean H-V in 10 patients with aortic gradients greater than 40 mm Hg was 62 +/- 5.6 msec compared with 47 +/- 3.1 msec in nine with gradients less than 40 (P less than 0.05). In patients with aortic stenosis and A-V block, the site of the block was distal to the His bundle in three and within the His bundle in five. All eight had calcified valves. Aortic stenosis was commonly associated with latent and manifest conduction disease in the His bundle and the trifascicular conduction system. Conduction disease was more extensive with calcified valves and greater valve obstruction.

Adult↗
PubMed1976

Differential effects of vasopressin on the water, calcium and lysosomal enzyme contents of mitochondria-rich and lysosome-rich (granular) epithelial cells isolated from bullfrog urinary bladder.

Treatment of bullfrog urinary bladder with arginine vasopressin (AVP) elicited a dose-dependent increase in the basal movement of water and sodium across isolated tissues. Epithelial cells from the mucosal surface and incubated with 10 mU AVP/ml for 30 min retained a greater amount of intracellular water and calcium than cells not treated with hormone. The epithelial cells were further separated into two major fractions by density gradient centrifugation; cells damaged during these manipulations were separated from viable cells and discarded. Morphologcal examination of the two respective fractions indicated that they largely consisted of mitochondria-rich (MR) and granular (G) cell types which line the lumen of bullfrog bladder. The calcium content of MR cells averaged 25% greater than that of G-type cells. G cells had a markedly higher content of the characteristic lysosomal hydrolases, acid phsophatase and cathepsin B1, than that found in MR cells. Incubation of G cells with AVP elicited significant increments in water and calcium contents and extracellular release of lysosomal enzymes as compared to untreated cells. Among MR cells treated with AVP, cell calcium declines slightly but no significant increase in water content or extracellular hydrolase activity was detected in comparison with paired control cells. The physiological significance of acid proteinase release from G cells treated with AVP was evaluated in experiments with intact bladder. Proteinase inhibitors which suppress the activity of cathepsin B1 selectively antagonized the action of hormone on water permeation. The data suggest that alterations in the calcium and lysosomal hydrolase activity associated with G cells exposed to AVP may contribute to the hormone-induced water flow observed across the intact epithelium.

Acid Phosphatase↗