Ten Holstein cows averaging 120 d in lactation were arranged in replicated 5 x 5 Latin squares with 3-wk periods to evaluate the role of sulfur (S) in the dietary cation-anion balance equation. Diets ...were based on corn silage in Exp. 1 and sorghum silage in Exp. 2. Supplemental S and chloride (Cl) from the double sulfate of potassium and magnesium and CaCl2 were used to manipulate dietary cation-anion balance from 0 to +30 meq when expressed as meq (Na + K)-(Cl + S)/100 g diet DM and from +19 to +49 meq when expressed as meq (Na + K)-Cl/100 g diet DM. Blood pH was not affected by cation-anion balance, although both S and Cl supplementation tended to lower pH. Blood HCO3- and urine pH decreased and plasma calcium (Ca) and urinary Ca excretion increased as anion was added to the diet. Milk fat production tended to be increased by the low S supplementation. Dietary Cl and S had similar effects on acid-base status. Therefore, we suggest that S be included with Cl in the dietary cation-anion balance equation for lactating dairy cows as follows: meq (Na + K)-(Cl + S)/100 g diet DM. Although response of acid-base status to S and Cl was similar, as more data comparing the acidogenicity of S vs Cl become available, it may be necessary to include a modifying coefficient for S in the equation to adjust for differences between S and Cl in acid-generating potential. This coefficient may be further dependent on the dietary source of S.
Objective: We sought to assess the efficacy of a clinical protocol to reduce the incidence of early-onset neonatal group B Streptococcus (GBS) infection. Study design: We assessed neonatal sepsis ...from GBS and other organisms with use of a before-after study design to evaluate the effects of implementation of combined intrapartum antimicrobial prophylaxis given selectively to mothers with GBS risks and penicillin G given to all neonates. Results: In 1994, early-onset GBS infection developed in 31 of 13,887 live births (2.2/1000), 13 preterm and 18 term cases. After implementation of the prophylaxis protocol (1995), 6 of 13,527 live births had early-onset GBS (0.4/1000) (P < .001). There were no preterm (P = .0004) and 6 term GBS cases (P = .02). The efficacy continued through 1999 (0.5/1000) without an increase in neonatal infections from other bacteria. Conclusion: Combined maternal and infant antimicrobial prophylaxis can significantly and safely reduce rates of early-onset GBS infection in both preterm and term infants. (Am J Obstet Gynecol 2002;186:618-26.)
While murine CD4 super(+)CD39 super(+) regulatory T cells (T sub(reg)) co-express CD73 and hydrolyze exogenous (e) adenosine triphosphate (ATP) to immunosuppressive adenosine (ADO), surface ...co-expression of CD73 on human circulating CD4 super(+)CD39 super(+) T sub(reg) is rare. Therefore, the ability of human T sub(reg) to produce and utilize ADO for suppression remains unclear. Using mass spectrometry, we measured nucleoside production by subsets of human CD4 super(+)CD39 super(+) and CD4 super(+)CD39(-)CD73 super(+) T cells or CD19 super(+) B cells isolated from blood of 30 volunteers and 14 cancer patients. CD39 and CD73 expression was evaluated by flow cytometry, Western blots, confocal microscopy or reverse transcription-polymerase chain reaction (RT-PCR). Circulating CD4 super(+)CD39 super(+) T sub(reg) which hydrolyzed eATP to 5'-AMP contained few intracytoplasmic granules and had low CD73mRNA levels. Only 1% of these T sub(reg) were CD39 super(+)CD73 super(+). In contrast, CD4 super(+)CD39 super(neg)CD 73 super(+) T cells contained numerous CD73 super(+) granules in the cytoplasm and strongly expressed surface CD73. In vitro-generated T sub(reg) (Tr1) and most B cells were CD39 super(+)CD73 super(+). All these CD73 super(+) T cell subsets and B cells hydrolyzed 5'-AMP to ADO. Exosomes isolated from plasma of normal control (NC) or cancer patients carried enzymatically active CD39 and CD73 super(+) and, when supplied with eATP, hydrolyzed it to ADO. Only CD4 super(+)CD39 super(+) T sub(reg) co-incubated with CD4 super(+)CD73 super(+) T cells, B cells or CD39 super(+)CD73 super(+) exosomes produced ADO. Thus, contact with membrane-tethered CD73 was sufficient for ADO production by CD4 super(+)CD39 super(+) T sub(reg). In microenvironments containing CD4 super(+)CD73 super(+) T cells, B cells or CD39 super(+)CD73 super(+) exosomes, CD73 is readily available to CD4 super(+)CD39 super(+)CD73 super(neg) T sub(reg) for the production of immunosuppressive ADO.
A correlation of the catalytic properties of three supported Pt catalysts with their physical properties, chemical composition, and adsorption properties is presented. The catalytic properties of ...0.75 wt% Pt/silica, 0.89 wt% Pt/alumina, and 0.48 wt% Pt/molybdena are reported for the hydrogenolysis of cyclopropane and for the hydrogenations of ethene, 1,3-butadiene, and 2-butyne. The corresponding catalytic properties of the standard reference catalyst EUROPT-1, a 6.3 wt% Pt/silica, are reported for comparison. Pt/silica and EUROPT-1 each contained fully reduced Pt and were chloride free; their activities for structure-insensitive 1,3-butadiene and 2-butyne hydrogenations were in proportion to their respective Pt dispersions and product selectivities were identical. This intercatalyst comparison could not be extended to ethene hydrogenation because reaction over Pt/silica showed a kinetic discontinuity which is described in detail. Pt/alumina contained Ptδ+which had the effect of reducing activity in each hydrogenation reaction and of altering product selectivity in 1,3-butadiene hydrogenation. A condition was found under which this support effect was reversed. Cyclopropane hydrogenolysis over all four catalysts obeyed the Bond–Newham rate equation, and the rate coefficient varied with Pt particle size indicating the reaction to be structure sensitive. Pt/molybdena, the only catalyst having a wide range of Pt particle size, behaved in contrasting and predictable ways depending upon the structure-sensitive or-insensitive nature of the reaction under study.
The individual contributions of glycoprotein Ib (GPIb) and the seven transmembrane domain receptor (STDR) to increases in platelet Ca2+i induced by α-thrombin or the tethered ligand peptide (TLP; ...SFLLRNPNDKYEPF) have been determined in control platelets, in platelets where the thrombin binding site on GPIb was blocked with the monoclonal antibodies TM60 and LJ-Ib10, in platelets where access of thrombin to the STDR was blocked by polyclonal antipeptide antibodies, and in Bernard-Soulier platelets which constitutively lack GPIb. Curve-fitting analyses (LIGAND) showed that binding of PPACK-thrombin and α-thrombin to the moderate-affinity site was not detected in the best-fit model in the presence of anti-STDR antibodies although with α-thrombin there was also decreased binding at the high-affinity site. Conversely, TM60 blocked binding of α-thrombin to the high-affinity site but also decreased binding at the moderate affinity site. Separately, either TM60 or anti-TNA (150 μg/mL) reduced thrombin (0.5 nM)-induced elevations in Ca2+i to 50% of control values, but Ca2+ elevations were essentially abrogated (4.2 ± 5%) when the two were added in combination. Ca2+i dose-response curves for α-thrombin were curvilinear and were only 50% of controls in the presence of anti-GPIb or anti-STDR antibodies at up to 10 nM α-thrombin, with their greatest sensitivity being below 2 nM. With Bernard-Soulier platelets, changes in Ca2+i were not detectable at ≤0.5 nM α-thrombin but were also 50% of controls at 5−10 nM α-thrombin. Ca2+i responses to TLP (1−100 μM) of antibody-blocked platelets were identical to those of controls whereas responses were ∼50% of controls in Bernard-Soulier platelets. The rate of increase in Ca2+i in controls was twice that seen in antibody-blocked platelets and about 5-fold greater than in Bernard-Soulier platelets. These results demonstrate that both GPIb and the STDR are required to ensure the optimal rate and extent of platelet activation over a range of α-thrombin concentrations (0.3−10 nM) and that the STDR corresponds to the previously described moderate-affinity thrombin receptor.
BACKGROUND & AIMS: Major histocompatibility complex (MHC) class II molecules are expressed on intestinal epithelial cells, and the intensity of this expression is regulated. The aim of this study was ...to test the hypothesis that bile regulates the expression of MHC class II molecules on intestinal epithelium.
METHODS: Rats were deprived of intestinal bile by external drainage for 24 or 48 hours, and their intestines were collected, sectioned, and stained with the anti-MHC class II monoclonal antibodies OX4 and OX6. For one group of rats, bile flow was deviated from its usual entry point to the ileum.
RESULTS: Compared with intact animals, MHC class II expression was observed to be diminished within 24 hours and totally absent after 48 hours of bile drainage. For the group in which bile flow was deviated to the ileum, staining was only observed in the region distal to the entry point. Analysis by bioassay and enzyme-linked immunosorbent assay of bile showed the presence of tumor necrosis factor and interferon gamma, respectively.
CONCLUSIONS: It is concluded that the presence of bile is required for the expression of MHC class II molecules on gut epithelium and that the cytokine components of bile may be the inducing agents. (Gastroenterology 1997 Dec;113(6):1901-5)
To determine whether BCG therapy could upregulate interleukin-6 (IL-6) production in human transitional cell carcinomas (TCC).
Immunohistochemistry of tumor biopsies and urinary cytospins and ELISA ...studies of urine from bladder cancer patients and TCC cell-line supernatants, before and after exposure to BCG, were performed.
Constitutive staining for IL-6 was found in the majority of bladder tumors. Interleukin-6 was detected in the urine of all 13 patients with carcinoma in situ and increased 5-fold during BCG therapy. Levels were variable but were greater in nonresponders (p less than 0.01). During therapy both detached bladder urothelial cells and polymorphonuclear leukocytes stained for IL-6. Production of IL-6 increased in only 3 cell lines after exposure to BCG, but all 7 cell lines showed increases after exposure to interferon-gamma (p =0.015). Grade 3 cell lines showed much greater upregulation than grade 1 and 2 cell lines.
The increase in IL-6 during BCG therapy may be caused by urothelial cells as well as leukocytes. The higher levels seen in nonresponders may be due to either higher grade or persisting tumor.
The objectives of the present study were to determine whether angiotensin II (Ang II) modifies beta-adrenoceptor-induced cAMP production in preglomerular microvascular smooth muscle cells (PMVSMCs), ...to determine whether the Ang II/beta-adrenoceptor interaction on cAMP production differs in PMVSMCs from normotensive Wistar-Kyoto (WKY) rats vs. PMVSMCs from spontaneously hypertensive rats (SHR), and to elucidate the mechanism of Ang II/beta-adrenoceptor interactions on cAMP production in PMVSMCs. In cultured PMVSMCs, isoproterenol increased cAMP levels and this effect was markedly enhanced by Ang II. The Ang II enhancement of isoproterenol-induced cAMP was significantly greater in SHR PMVSMCs compared with WKY PMVSMCs. Neither inhibition of calcineurin with FK506, inhibition of calcium-calmodulin with W-7 and calmidazolium, nor inhibition of Gi proteins with pertussis toxin attenuated Ang II enhancement of isoproterenol-induced cAMP in PMVSMCs from either SHR or WKY rats. Moreover, the effect of Ang II on isoproterenol-induced cAMP was not mimicked by alpha-2 adrenoceptor stimulation. In contrast, chelation of intracellular calcium with BAPTA-AM attenuated, increasing intracellular calcium with A23187 augmented, and inhibition of protein kinase C with either calphostin C or chelerythrine chloride abolished Ang II enhancement of isoproterenol-induced cAMP. We conclude that in cultured PMVSMCs Ang II enhances the cAMP response to beta-adrenoceptor agonists via a mechanism that involves coincident activation of adenylyl cyclase by stimulatory G proteins and protein kinase C. Thus, protein kinase C-mediated activation of adenylyl cyclase may attenuate Ang II-induced vasoconstriction in the renal microcirculation by raising the intracellular levels of cAMP, and this mechanism may be augmented in genetic hypertension.
For Ras oncoproteins to transform mammalian cells, they must be post-translationally modified with a farnesyl group in a reaction catalysed by the enzyme farnesyl-protein transferase (FPTase). ...Inhibitors of FPTase have therefore been proposed as anti-cancer agents. We show that L-744,832, which mimics the CaaX motif to which the farnesyl group is added, is a potent and selective inhibitor of FPTase. In MMTV-v-Ha-ras mice bearing palpable tumours, daily administration of L-744,832 caused tumour regression. Following cessation of treatment, tumours reappeared, the majority of which regressed upon retreatment. No systemic toxicity was found upon necropsy of L-744,832-treated mice. This first demonstration of anti-FPTase-mediated tumour regression suggests that FPTase inhibitors may be safe and effective anti-tumour agents in some cancers.
Aged homozygous apolipoprotein E gene-deficient (apoE −/−) mice have been proposed as an experimental model for the role of human apoE isoforms in Alzheimer's disease (AD). However, results from ...different laboratories have been in conflict regarding the presence or absence of neurodegeneration in these mice. Moreover, despite apoE being the major lipid trafficking molecule in the central nervous system, there has been no investigation of brain lipid levels in apoE −/− mice. Here we have examined male and female apoE −/− and control mice aged 10 to 12 months, testing the hypothesis that lack of apoE leads to some of the neuropathological changes seen in AD. Our results failed to demonstrate significant neurodegeneration, histopathological changes, or reduction in cerebral cortical synaptophysin in apoE −/− mice. However, we did observe a significant reduction in cerebral cortical phospholipids and their constituent fatty acids, as well as elevated lipid peroxidation products, in apoE −/− mice compared to apoE +/+ mice with the same genetic background. Our results suggest that the brains of aged apoE −/− mice display some of the lipid abnormalities associated with AD; however, these changes alone, at the magnitudes achieved in the apoE −/− mice, do not directly lead to the major neurodegenerative changes of AD.
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