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H Wiener

Publications and source records attributed to H Wiener.

At least 37 records · Page 2Linked to original sources
PubMed1996

Sum variance--a most valuable parameter in computer-assisted image analysis of voided urines.

The chromatin pattern of retrospectively Feulgen-Schiff-stained exfoliative urothelial cells was determined by computer-assisted analysis for 12 detailed texture image parameters. These were compared with density parameters and geometric parameters for their ability to discriminate between benign and malignant samples. The discriminatory power of the mean variable of the texture parameter sum variance was found to equal that of densitometric parameters which reflect the nuclear DNA content of the cell. The results suggest that determination of the texture parameter sum variance is valuable in distinguishing nuclei of specimens negative from those positive for malignancy.

Cell Nucleus↗
PubMed1996

Cytophotometry in the monitoring of bladder cancer under intravesical chemotherapy.

OBJECTIVE: We evaluated the DNA cytophotometry in 446 bladder washing samples from 64 patients under mitomycin C after superficial bladder cancer during an observation period of up to 5 years. The aim of the study was to identify patients at high risk of recurrence despite chemotherapy-induced atypical, hence noninformative cytology. METHODS: The prognostic value of cytology and ploidy during chemotherapy was compared with regard to recurrence rates and the median time to recurrence. RESULTS: Aneuploidy identified 8 of 10 patients recurring within 12 months out of 17 patients with atypia at first presentation after surgery, whereas no recurrence was seen after atypia and diploid histograms (p = 0.005, mean follow-up period 62 months). Aneuploidy was the most accurate indicator of short-time recurrence (p < 0.001 by multivariate analysis). Follow-up data showed a relative risk of recurrence of 12.7 following histogram shifts towards aneuploidy and of 1.6 for positive shifts in cytology. CONCLUSION: Cytophotometry is superior to cytology in predicting the outcome in patients under chemotherapy for superficial transitional cell cancer of the bladder.

Administration, Intravesical↗
PubMed1993

Aldosterone and thyroid hormone modulation of alpha 1-, beta 1-mRNA, and Na,K-pump sites in rabbit distal colon epithelium. Evidence for a novel mechanism of escape from the effect of hyperaldosteronemia.

Aldosterone and thyroid hormone regulation of Na,K-pump biosynthesis has been examined in the distal colon epithelium of rabbits. Qualitative analysis of alpha-subunit isoform distribution (alpha 1, alpha 2, alpha 3) detected only the alpha 1-mRNA in the distal colon epithelium and outer renal medulla, while all three isoforms were observed in rabbit brain. A low-sodium diet led to a rise in serum aldosterone from 0.6 nM to 1.4-1.9 nM and an increase of alpha 1-mRNA to 162%, beta 1-mRNA to 120%, and the number of Na,K-pump units as determined by specific [3H]-ouabain binding to 182% of control by the second day of the diet. While aldosterone levels remained elevated, a spontaneous decrease in serum levels of T3 and T4 to 50-60% of control from the third day of the diet was followed by downregulation of beta 1-mRNA to 55-67%, alpha 1-mRNA to 63-105%, and of [3H]-ouabain binding to 103% of control, suggesting that a reduced rate of synthesis of the beta 1-subunit is rate limiting for Na,K-pump biosynthesis. Substitution with T3 (10 micrograms/kg) at the seventh day with transient restoration of serum T3 to control levels, led to rapid accumulation of beta 1-mRNA to 152%, of alpha 1-mRNA to 135%, and of the number of Na,K-pump units to 153% of control. This is consistent with thyroid hormone having a permissive role for the aldosterone stimulation of Na,K-pump biosynthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldosterone↗
PubMed1993

Ca2+ activation and pH dependence of a maxi K+ channel from rabbit distal colon epithelium.

To determine if their properties are consistent with a role in regulation of transepithelial transport, Ca(2+)-activated K+ channels from the basolateral plasma membrane of the surface cells in the distal colon have been characterized by single channel analysis after fusion of vesicles with planar lipid bilayers. A Ca(2+)-activated K+ channel with a single channel conductance of 275 pS was predominant. The sensitivity to Ca2+ was strongly dependent on the membrane potential and on the pH. At a neutral pH, the K0.5 for Ca2+ was raised from 20 nM at a potential of 0 mV to 300 nM at -40 mV. A decrease in pH at the cytoplasmic face of the K+ channel reduced the Ca2+ sensitivity dramatically. A loss of the high sensitivity to Ca2+ was also observed after incubation with MgCl2, possibly a result of dephosphorylation of the channels by endogenous phosphatases. Modification of the channel protein may thus explain the variation in Ca2+ sensitivity between studies on K+ channels from the same tissue. High affinity inhibition (K0.5 = 10 nM) by charybdotoxin of the Ca(2+)-activated K+ channel from the extracellular face could be lifted by an outward flux of K+ through the channel. However, at the ion gradients and potentials found in the intact epithelium, charybdotoxin should be a useful tool for examination of the role of maxi K+ channels. The high sensitivity for Ca2+ and the properties of the activator site are in agreement with an important regulatory role for the high conductance K+ channel in the epithelial cells.

Animals↗
PubMed1992

Vanadium-induced Cl(-)-secretion in rabbit descending colon is mediated by prostaglandins.

Vanadium in the 4+ (vanadyl-ion) and 5+ (vanadate-ion) oxidation state stimulates furosemide-sensitive electrogenic Cl- secretion in isolated epithelia of rabbit descending colon. This effect is associated with an increased release of prostaglandin E2 from the tissue. Inhibitors of phospholipase A2 or cyclooxygenase abolish both vanadium-induced release of prostaglandin E2 and Cl- secretion. Neuronal mechanisms are not likely to be involved, as tetrodotoxin does not affect the vanadate induced Cl- secretion. Although vanadate is known to inhibit Na+,K(+)-ATPase activity, no inhibition of active Na+ transport was observed in intact colonic epithelia suggesting a rapid intracellular reduction of vanadate ions to vanadyl ions which have no inhibitory effect on the Na+,K(+)-ATPase. The present findings therefore indicate that vanadate stimulated colonic Cl- secretion involves intracellular conversion of vanadate to vanadyl and release of prostaglandin E2.

Animals↗
PubMed1991

Cellular localization of PNA binding in colorectal adenomas: comparison with differentiation, nuclear:cell height ratio and effect of desialylation.

The lectin Arachis Hypogaea (Peanut Agglutinin, PNA) was used to study the cellular localization of the Thomsen-Friedenreich (T) disaccharide Gal-beta (1-3)-GalNAc alpha 1-R in 22 formalin-fixed paraplast-embedded colorectal adenomas of varying cellular dysplasia. An indirect immunoperoxidase method was used prior to and after neuraminidase treatment. Detailed information on the cellular localization of PNA binding was obtained. In addition, morphometric measurements of the nuclear: cell height ratios were performed on staining-filtered micrographs of crypts from all adenomas. We found 1) a statistically significant increase in the nuclear:cell height ratio with increasing grade of dedifferentiation (p less than 0.003), 2) a statistically significant smaller nuclear:cell height ratio in crypts that were PNA-positive in the Golgi region when these were compared to crypts that were PNA-positive on luminal cell membranes, 3) a decreasing number of crypts expressing PNA binding sites in the Golgi region with increasing dedifferentiation, leading to complete absence of PNA binding sites in Grade IV adenomas, 4) neuraminidase pretreatment increased the number of crypts expressing PNA binding sites in cytoplasm and on luminal membranes, whereas no changes were detected in crypts expressing PNA binding sites in the Golgi region. Our results confirm the general concept of accumulation of precursors of carbohydrate antigens in dedifferentiated cells. On the basis of the results presented, we conclude that the nuclear:cell height ratio shows a good correlation with the cellular localization of PNA binding, cellular differentiation and classic pathologic grading.

Adenoma↗
PubMed1990

Calcium-activated potassium channels in basolateral membranes of colon epithelial cells; reconstitution and functional properties.

Using differential sedimentation, isopycnic and Ficoll-400 barrier centrifugation, basolateral membrane vesicles of surface and crypt cells of the rabbit distal colon were enriched 34- and 9-fold, respectively. 86Rb(+)-uptake into these vesicles, driven by an electrical potential difference, was stimulated by submicromolar Ca2+ activities and inhibited by Ba2+. These findings indicate the presence of Ca2(+)-activated K+ channels. The K+ channels in surface and crypt cell membranes differed with respect to inhibition by the bee venom apamin, the scorpion venom charybdotoxin and tetraethylammonium and exhibited a different pH dependence. Fusion of basolateral membrane vesicles with planar phospholipid bilayers revealed the presence of high-conductance Ba2(+)-sensitive K+ channels which were activated by micromolar Ca2+ and inhibited by crude scorpion venom and trifluoperazine. These K+ channels may be involved in the coupling of apical and basolateral membrane conductances during Na+ absorption and Cl- secretion, but they may also play a role in cell volume regulation.

Animals↗
PubMed1990

Rabbit distal colon epithelium: III. Ca2(+)-activated K+ channels in basolateral plasma membrane vesicles of surface and crypt cells.

In the mammalian distal colon, the surface epithelium is responsible for electrolyte absorption, while the crypts are the site of secretion. This study examines the properties of electrical potential-driven 86Rb+ fluxes through K+ channels in basolateral membrane vesicles of surface and crypt cells of the rabbit distal colon epithelium. We show that Ba2(+)-sensitive, Ca2(+)-activated K+ channels are present in both surface and crypt cell derived vesicles with half-maximal activation at 5 x 10(-7) M free Ca2+. This suggests an important role of cytoplasmic Ca2+ in the regulation of the bidirectional ion fluxes in the colon epithelium. The properties of K+ channels in the surface cell membrane fraction differ from those of the channels in the crypt cell derived membranes. The peptide toxin apamin inhibits Ca2(+)-activated K+ channels exclusively in surface cell vesicles, while charybdotoxin inhibits predominantly in the crypt cell membrane fraction. Titrations with H+ and tetraethylammonium show that both high- and low-sensitive 86Rb+ flux components are present in surface cell vesicles, while the high-sensitive component is absent in the crypt cell membrane fraction. The Ba2(+)-sensitive, Ca2(+)-activated K+ channels can be solubilized in CHAPS and reconstituted into phospholipid vesicles. This is an essential step for further characterization of channel properties and for identification of the channel proteins in purification procedures.

Animals↗
PubMed1990

Active Ca2+ transport systems in basolateral membranes from rabbit distal colon.

Active Na+ absorption by tight epithelia such as frog skin and distal colon share common features like feedback inhibition of cellular [Na+] on Na+ influx through amiloride-sensitive Na+ channels. It is postulated that the negative feedback of increasing cell [Na+] is mediated via a rise in cell [Ca2+]. In this model, cell [Na+] is coupled to cell [Ca2+] via a Na+/Ca2+ exchange system in the basolateral membrane. In the present study, the Ca2+ transporting systems in rabbit distal colon basolateral membranes were characterized. ATP-dependent Ca2+ uptake could be demonstrated in membrane vesicles from surface cells with the following kinetic parameters: Km = 0.09 microM Ca2+ and Vm = 3.8 nmol Ca2+ mg-1 protein min-1. The ATP-dependent Ca2+ transport was not responsive to ruthenium red and oxalate, suggesting a plasmalemmal origin. The addition of 75 mM Na+ to the uptake medium, 10 min after addition of ATP, did not release Ca2+ from the vesicles in significant amounts. In the absence of ATP, outwardly directed Na+ gradients were incapable of stimulating Ca2+ uptake. This study demonstrates that rabbit distal colon epithelium lacks a well-defined Na+/Ca2+ exchange system, and (Ca2+, Mg2+)-ATPase appears to be the sole Ca2+ extrusion system. Alternatives for the coupling of cell [Na+] to cell [Ca2+] are discussed.

Animals↗
PubMed1989

Rabbit distal colon epithelium: I. Isolation and characterization of basolateral plasma membrane vesicles from surface and crypt cells.

A method has been developed for the simultaneous isolation of basolateral plasma membrane vesicles from surface and crypt cells of rabbit distal colon epithelium by sequential use of differential sedimentation, isopycnic centrifugation and Ficoll 400 barrier centrifugation. The protein yield was high (total 0.81 mg/g mucosa) and surface and crypt cell-derived basolateral membrane fractions have been purified 34- and 9-fold with respect to the homogenate. The pattern of marker enzyme enrichments revealed only minor contamination by subcellular organelles. Latency of ouabain-sensitive (Na+,K+)-ATPase activity prior and after trypsin treatment of membranes indicated a vesicle configuration of sealed right side-out: sealed inside-out: leaky of approximately 2:1:1. The presence of sealed vesicles was also evident from the osmotic sensitivity of the D-[1-14C] mannitol equilibrium space determined with either fraction. Although considerably different in protein profile, surface and crypt basolateral membranes were similar in cholesterol to phospholipid molar ratio and membrane fluidity as determined by steady-state fluorescence polarization. Stopped-flow light scattering experiments revealed a rather low water permeability of the membranes with a permeability coefficient of 6 microns/sec at 35 degrees C, which is one order of magnitude lower than reported for small intestinal plasma membranes. Both membrane fractions have been shown to effectively generate outward uphill potassium ion gradients, a process that is energized by ATP and inhibited by the membrane-permeant cardiac-glycoside digitoxin. These characteristics are consistent with the activity of a (Na+,K+) pump operating in inside-out vesicles.

Animals↗
PubMed1989

Rabbit distal colon epithelium: II. Characterization of (Na+,K+,Cl-)-cotransport and [3H]-bumetanide binding.

Loop diuretic-sensitive (Na+,K+,Cl-)-cotransport activity was found to be present in basolateral membrane vesicles of surface and crypt cells of rabbit distal colon epithelium. The presence of gradients of all three ions was essential for optimal transport activity. (Na+,K+) gradient-driven 36Cl fluxes were half-maximally inhibited by 0.14 microM bumetanide and 44 microM furosemide. While 86Rb uptake rates showed hyperbolic dependencies on Na+ and K+ concentrations with Hill coefficients of 0.8 and 0.9, respectively, uptakes were sigmoidally related to the Cl concentration, Hill coefficient 1.8, indicating a 1 Na+:1 K+:2 Cl stoichiometry of ion transport. The interaction of putative (Na+,K+,Cl-)-cotransport proteins with loop diuretics was studied from equilibrium-binding experiments using [3H]-bumetanide. The requirement for the simultaneous presence of Na+,K+, and Cl-, saturability, reversibility, and specificity for diuretics suggest specific binding to the (Na+,K+,Cl-)-cotransporter. [3H]-bumetanide recognizes a minimum of two classes of diuretic receptor sites, high-affinity (KD1 = 0.13 microM; Bmax1 = 6.4 pmol/mg of protein) and low-affinity (KD2 = 34 microM; Bmax2 = 153 pmol/mg of protein) sites. The specific binding to the high-affinity receptor was found to be linearly competitive with Cl- (Ki = 60 mM), whereas low-affinity sites seem to be unaffected by Cl-. We have shown that only high-affinity [3H]-bumetanide binding correlates with transport inhibition raising questions on the physiological significance of diuretic receptor site heterogeneity observed in rabbit distal colon epithelium.

Animals↗
PubMed1989

An outbreak of hookworm infection associated with military operations in Grenada.

During 1983, a multinational military intervention took place on Grenada. After deployment, troops from several U.S. Army units noted signs and symptoms consistent with soil-transmitted helminthic infection. Of 684 soldiers screened five to seven weeks post-deployment, over 20% reported abdominal pain and/or diarrhea during or after the action. Eosinophilia of at least 10% was observed in 119 (22.5%) of 529 soldiers evaluated further; eosinophilia of 5-9% was documented in another 126 (23.8%) of the 529 soldiers. Stool examinations confirmed hookworm infection in 35 soldiers. One case of strongyloidiasis was also documented. Infection was attributed to ground exposure near homes with compromised sanitation. Units that joined the operation after the initial assault phase were at low risk of hookworm infection.

Disease Outbreaks↗
PubMed1986

Heterogeneity of dog-liver glutathione S-transferases. Evidence for a unique temperature dependence of the catalytic process.

Dog liver glutathione S-transferase activities are associated with five cytosolic proteins and to approximately 1.5% with microsomal proteins determined on the basis of activity conjugating to 1-chloro-2,4-dinitrobenzene. The four major cytosolic enzymes were purified to apparent homogeneity by sequential use of ion-exchange, hydrophobic, hydroxyapatite and affinity chromatography. The isolated transferases are binary combinations of three classes of subunits: alpha (Mr = 26,000), beta (Mr = 27,000), gamma (Mr = 28,500). They were classified by roman numerals assigned in order of increasing isoelectric point as DI alpha gamma (pI 6.4), DII alpha alpha (pI 6.9), DIII beta gamma (pI 8.1), and DIV beta gamma (pI 8.7). Additionally, traces of conjugating activity may be attributed to a, beta monomeric or dimeric protein with cationic character. The differences in catalytic specificity, temperature and pH dependence of activity, and sensitivity and kinetic response to inhibitory ligands may reflect the intrinsic structural heterogeneity of the transferases. At physiological glutathione concentrations DI alpha gamma accounted for roughly 60% of the total 1-chloro-2,4-dinitrobenzene-conjugating activity, the rank order of activity being DI alpha gamma greater than DII alpha alpha greater than DIV beta gamma greater than DIII beta gamma. The glutathione-dependent denitration of organic nitrates seems to be restricted to the cationic enzymes, whereas 1,2-dichloro-4-nitrobenzene-conjugating activity is exclusively associated with the anionic transferases, DI alpha gamma much greater than DII alpha alpha. Arrhenius plots from initial rate experiments performed over a range of temperatures (15-40 degrees C) exhibit an upward bend for DI alpha gamma, an apparently constant slope for DII alpha alpha and DIII beta gamma, and a downward bend for DIV beta gamma.

Anilino Naphthalenesulfonates↗
PubMed1986

Sodium absorption and potassium secretion in rabbit colon during sodium deficiency.

Reducing the daily Na intake of rabbits from approximately 4.4 to 0.1 meq/kg body wt increases plasma aldosterone levels and the rate of amiloride-sensitive Na transport in the descending colon two- to threefold. The stimulation of Na transport is a result of an increase in the maximum transport capacity of the epithelium, whereas the affinity of Na to its transport system is not altered. Simultaneous with enhanced Na absorption, there is statistically significant K secretion of 0.25 mu eq . cm-2 . h-1 under short-circuit conditions. Transepithelial current-voltage relations in the absence and presence of amiloride were used to determine the Na permeability of the apical membrane and the intracellular Na activity of the Na-transporting cells. The Na content of the amiloride-sensitive cells was estimated from the kinetics of absorptive Na tracer fluxes. The stimulation of active Na transport under conditions of dietary Na restriction is associated with parallel increases in apical membrane Na permeability and the Na content of the amiloride-sensitive cells, but the intracellular Na activity and the activity of the epithelial Na-K-ATPase are not significantly altered. Taken together, these results suggest that endogenous aldosterone increases the number of conducting Na entry sites in the apical membrane of colonic epithelium and that there is activation of additional Na pump units in the basolateral membrane, brought about by cell swelling and possibly by an increase in the fraction of epithelial cells that participate in active Na transport.

Absorption↗
PubMed1985

Influence of sulfasalazine, 5-aminosalicylic acid and sulfapyridine on prostanoid synthesis and metabolism in rabbit colonic mucosa.

The effects of sulfasalazine (SASP) and its cleavage products 5-aminosalicylic acid (5-ASA) and sulfapyridine (SP) on prostanoid (PG) synthesis and degradation were determined in rabbit colonic mucosa fractions in vitro. When the microsomal fraction was incubated with (14C)arachidonic acid, 10(-3) M SASP and SP did not markedly change the formation of labeled PGE2, PGF2 alpha, TxB2 and 6-keto-PGF1 alpha X 10(-4) M 5-ASA increased synthesis about 2.7-fold; the pattern of PG identified was unaltered. In the presence of the 10-fold higher concentration of 5-ASA, PG synthesis remained elevated at a similar level. When the cytosolic fraction was incubated with (3H)PGE2, 10(-3) M 5-ASA was without influence and 10(-3) M SP decreased slightly PGE2 breakdown. However, SASP showed a pronounced inhibitory effect at 10(-5) M and inhibition of PGE2 degradation was complete at 10(-3) M SASP. The results are compatible with the assumption that stimulation of PG synthesis by 5-ASA is related to therapeutic benefit in the treatment of ulcerative colitis.

Aminosalicylic Acids↗
PubMed1983

Metabolism and disposition of 2',3'-di-O-nitro-adenosine-5'-(N-ethyl-carboxamide) in dogs.

2',3'-Di-O-nitro-[8-3H]-adenosine-5'-(N-ethyl-carboxamide) (20 micrograms/kg) was denitrated completely within 1-3 hr in perorally and intravenously dosed dogs. Extremely rapid disappearance of the unchanged drug in serum was parallelled by the instantaneous appearance of mononitrates with 3'-mononitrate levels exceeding those of 2'-mononitrate three-fold. The mononitrates were eliminated with a half-life of 30-70 min, giving rise to the completely denitrated product, adenosine-5'-(N-ethyl-carboxamide) (NECA). The latter product was not further metabolized and was eliminated with a half-life of about 4 hr. Urinary excretion averaged 50% of the administered dose within 4 days and was represented essentially by the completely denitrated drug. Volatile 3H-label of the drug was found in serum and urine during in vivo experiments. Oral bioavailability of the drug was about 90%. In vitro studies indicated that thiols are involved in denitration and reactions are catalysed by glutathione S-transferases, which were partially purified from dog liver. Nitrate ester cleavage was more easily accomplished at the 2'-position than at the 3'-position of the drug and resulted in the liberation of inorganic nitrite. Comparison of in vitro denitration rates gave the following ranking order; 2',3'-di-O-nitro-NECA greater than isosorbide-2,5-dinitrate greater than 2'-nitro-NECA greater than 3'-nitro-NECA greater than isosorbide-2-mononitrate, while nitrate ester cleavage of isosorbide-5-mononitrate was not detectable.

Adenosine↗
PubMed1983

Theoretical analysis of adenosine release from cardiac tissue as influenced by transport inhibitors.

The release of adenosine from cardiac tissue was simulated by use of a model equation which consists of a saturable transfer term for both unidirectional influx and efflux, representing a symmetrical facilitated diffusion mechanism. This proposed model can account for positive and negative changes in adenosine release from cardiac tissue brought about by competitive transport inhibitors.

Adenosine↗