Reduced susceptibilities of Shigella sonnei strains isolated from patients with dysentery to fluoroquinolones

Seven clinical isolates of Shigella sonnei with reduced susceptibilities to fluoroquinolones (sparfloxacin, ciprofloxacin, and ofloxacin) were obtained. The MICs of fluoroquinolones against these S. sonnei strains were 16 to 32 times higher than those obtained against typical strains that are highly susceptible to these agents. The kinetics of [14C]ofloxacin accumulation in these clinical strains were not different from those in the fully susceptible strains. However, DNA synthesis was much less inhibited by ofloxacin in the strains with reduced susceptibility. Analysis of the in vitro activity of the partially purified DNA gyrase from these isolates showed that the decreased quinolone susceptibility of the S. sonnei strains was likely due to mutation of the DNA gyrase subunit A gene.

Cytosolic protein phosphatase may turn off activated NADPH oxidase in guinea pig neutrophils

Protein phosphatase inhibitors, okadaic acid and calyculin A, potentiated and elongated N-formyl-methionyl-leucyl-phenylalanine-induced superoxide anion (O2-) production in guinea pig neutrophils. The activity of NADPH oxidase in the membrane fraction prepared from phorbol 12-myristate 13-acetate-stimulated neutrophils was inactivated by the addition of the cytosol from resting neutrophils, such inactivation of NADPH oxidase was also suppressed by the protein phosphatase inhibitors. We previously reported that phosphorylation of the 46-kDa protein by protein kinase C is one of the activation mechanisms of NADPH oxidase-dependent superoxide anion production. In the cytosol fraction, we found protein phosphatase activity that catalyzed dephosphorylation of 32P-labeled phosphoproteins including the 46-kDa protein. Dephosphorylation of the 46-kDa protein was inhibited by the addition of okadaic acid and calyculin A. These results indicate that dephosphorylation of the 46-kDa protein by protein phosphatase is involved in the inactivation of NADPH oxidase. NADPH oxidase activity in guinea pig neutrophil may be regulated by the phosphorylation/dephosphorylation state of the 46-kDa protein by protein kinase C and protein phosphatase.

Role of P-glycoprotein in renal tubular secretion of digoxin in the isolated perfused rat kidney

The mechanism for renal tubular secretion of digoxin as well as its interaction with quinidine or verapamil were investigated using the isolated perfused rat kidney. [3H]Digoxin was instantaneously administered into the renal artery together with [14C]inulin and Evans blue-albumin, and renal venous and urinary outflow curves were measured. The ratio of fractional excretion to filtration fraction for digoxin was 2.40 +/- 0.40, indicating involvement of tubular secretion. Quinidine and verapamil decreased the ratio of fractional excretion to filtration fraction in a concentration-dependent manner, and this inhibition was indicated to occur at transport from cells to lumen across luminal membranes. Neither tetraethylammonium nor p-aminohippurate affected the renal handling of digoxin. Because ouabain and digitoxose showed no influence on the value of fractional excretion to filtration fractions, Na+,K(+)-ATPase is not involved in the tubular secretion of digoxin. A metabolic inhibitor, 2,4-dinitrophenol, markedly inhibited digoxin secretion. Agents that bind to P-glycoprotein, such as vinblastine, daunorubicin and reserpine, markedly inhibited the secretion of digoxin. Recently, we have found that digoxin is a substrate transported by P-glycoprotein. The findings obtained here support the hypothesis that digoxin is secreted by P-glycoprotein located on the luminal membrane of renal tubular epithelial cells, and that clinically important interactions with quinidine and verapamil are caused by the inhibition of P-glycoprotein.

Digoxin-cyclosporin A interaction: modulation of the multidrug transporter P-glycoprotein in the kidney

The mechanism of a renal tubular digoxin-cyclosporin A interaction was elucidated using a kidney epithelial cell line and the isolated perfused rat kidney. The cells expressed an excess amount of human P-glycoprotein on the apical membranes by transfection with MDR1 cDNA. Cyclosporin A inhibited the transepithelial transport of digoxin mediated by human P-glycoprotein; net basal-to-apical transport across the cell monolayer was 22.8, 21.2, 6.61 and 0.91 pmol/mg of protein/3 hr in the presence of 0, 1, 5 and 10 microM cyclosporin A, respectively. Cyclosporin A also reduced the renal tubular secretion of digoxin by the kidney. The ratio of fractional excretion/filtration fraction for digoxin was 2.88 +/- 0.71 (mean +/- S.D.) in the control, and this was decreased to 1.21 +/- 0.09 and 1.05 +/- 0.13 in the presence of 1 and 5 microM cyclosporin A, respectively. Because no signs of acute nephrotoxicity were observed, a direct effect of cyclosporin A accounted for the reduced secretion. On the other hand, digoxin did not affect cyclosporin A transport by P-glycoprotein. These findings indicate that serum concentrations of digoxin in patients should be carefully monitored when administered concurrently with cyclosporin A. The present transepithelial transport system using the transfectant cells is a simple and useful screening system for predicting drug interactions that can occur in a clinical situation.

Effect of thiol compounds on in vitro development and intracellular glutathione content of bovine embryos

The purpose of this investigation was to determine the effect of beta-mercaptoethanol (beta-ME) and cysteamine, low-molecular-weight thiol compounds, on the development and intracellular glutathione content of bovine embryos obtained by in vitro fertilization of in vitro-matured oocytes. Embryos developed to the 6-8-cell stage after in vitro fertilization were cultured without feeder cells in TCM-199 containing 10% fetal calf serum with or without beta-ME or cysteamine. The percentage of embryos that developed to the blastocyst and hatched blastocyst stages were significantly higher in medium containing beta-ME or cysteamine. Also, total intracellular glutathione levels were higher for embryos cultured in the medium with beta-ME or cysteamine than for those cultured in medium without thiol compounds. Moreover, when buthionine sulfoximine, a specific inhibitor of glutathione synthesis, was added to medium containing thiol compounds, there was a reduction both in the development of embryos to the blastocyst stage and in intracellular glutathione content. These results indicate that the inclusion of low-molecular-weight thiol compounds aids the in vitro development of bovine embryos without feeder cells and that the effect of thiol compounds is mediated through the increase of intracellular glutathione levels.

[Characteristics of the Shigella flexneri strains isolated from Japanese monkeys (Macaca fuscata)]

Shigella flexneri was isolated from 11 of 95 Japanese monkeys (Macaca fuscata) purchased by the Animal Research Center, Tokyo Medical and Dental University, during the period from 1988 through 1990. The serotypes of the isolates were 4a (5 isolates), 2a (4 isolates), 2b (1 isolate), and varY (1 isolate). Although some of the strains in the same serotypes were similar, others were different in their antibiotic susceptibility patterns or the plasmid profiles. Our results suggested that various types of Shigella flexneri had infected the Japanese monkeys. However, the source(s) and the routes of infection were unclear. Dysentery in the Japanese monkey has not yet been reported. So, to our knowledge, this may be the first report of dysentery among Japanese monkeys.

Enhanced liver regeneration in rats treated with 15-deoxyspergualin alone and in combination with FK 506

The effects of 15-deoxyspergualin (DSG) alone and in combination with FK 506 (FK) on liver regeneration after 2/3 hepatectomy was studied. The administration of 5 mg/kg DSG increased the liver weight as a percentage of the body weight (RLW) in the 5 days following the hepatectomy. This enhanced regeneration was not affected if interleukin(IL)-2 was also given. The combination of 1 mg/kg DSG and 0.05 mg/kg FK induced the highest values for RLW. The amounts of food and water intake increased in the DSG and FK combined group. Blood chemistry indicated that the combined administration of DSG and FK could reduce side-effects more effectively than separate administration. These observation led us to conclude that DSG has a stimulating potency in liver regeneration by means of direct suppression of T cell activation, and there is a synergistic effect on regeneration by DSG and FK.

Chemical analysis of lipopolysaccharides of Shigella sonnei form II strains expressed by cloned form I antigen genes

A compositional sugar analysis was carried out on lipopolysaccharide (LPS) from Shigella sonnei form II in which a plasmid with cloned form I antigen genes had been introduced. The recipient form II strains contained galactose, glucose, heptose, glucosamine, and 2-keto-3-deoxyoctonic acid (KDO) (2: 3: 1: 2: 2) in its LPS, while the transformant form I LPS contained, besides these sugars, N-acetyl-L-altrosaminouronic acid as an additional sugar constituent, which is known to be one of the antigenic determinants of form I antigen.

Forskolin stimulates porcine sperm capacitation by increasing calcium uptake

Using the fluorescent calcium indicator fura-2, forskolin was found to dose-dependently cause an immediate increase in the concentration of intracellular free calcium of porcine cauda epididymal sperm. This stimulatory effect of forskolin is due to the enhancement of Ca2+ uptake by the verapamil-sensitive transporter on the sperm plasma membrane and results in the promotion of the sperm capacitation and subsequent acrosome reaction.

Human P-glycoprotein transports cortisol, aldosterone, and dexamethasone, but not progesterone

We expressed human MDR1 cDNA isolated from the human adrenal gland in porcine LLC-PK1 cells. A highly polarized epithelium formed by LLC-GA5-COL300 cells that expressed human P-glycoprotein specifically on the apical surface showed a multidrug-resistant phenotype and had 8.3-, 3.4-, and 6.5-fold higher net basal to apical transport of 3H-labeled cortisol, aldosterone, and dexamethasone, respectively, compared with host cells. But progesterone was not transported, although it inhibited azidopine photoaffinity labeling of human P-glycoprotein and increased the sensitivity of multidrug-resistant cells to vinblastine. An excess of progesterone inhibited the transepithelial transport of cortisol by P-glycoprotein. These results suggest that cortisol and aldosterone are physiological substrates for P-glycoprotein in the human adrenal cortex and that substances that efficiently bind to P-glycoprotein are not necessarily transported by P-glycoprotein.

Localization of a maturation-dependent epididymal sperm surface antigen recognized by a monoclonal antibody raised against a 135-kilodalton protein in porcine epididymal fluid

A specific 135-kDa protein was purified from porcine cauda epididymal fluid. Analysis of its N-terminal amino acid sequence revealed it to be a new protein. Stable clones of hybridomas that produced monoclonal antibodies against the purified 135-kDa protein were established. A clone, B-11, reacting both with epididymal fluid and with sperm plasma membranes was selected and used in this study. Immunoblotting analysis showed that B-11 reacted only with a 135-kDa protein among epididymal fluid proteins. In contrast, B-11 did not recognize a similar 135-kDa sperm protein but did strongly react with a 27-kDa protein among sperm membrane proteins, extracted by NP-40 in the presence of protease inhibitors. B-11 also reacted only with a 27-kDa protein fragment among trypsin digests of the 135-kDa epididymal protein. The 135-kDa protein was first detected, by ELISA or immunoblotting analysis, at the beginning of the corpus epididymis. Maximal levels were reached in the distal corpus and levels were slightly decreased in the cauda epididymis. On the other hand, the surface of caput sperm were found to contain small amounts of antigen(s), the concentration of which gradually increased during epididymal transit. In immunocytochemical studies, the antigen was detectable in the epithelial cells from the initial segment to the corpus of the epididymis but not in the caudal cells. In the lumen, the presence of the 135 kDa protein was apparent in the corpus (at a maximum in the middle and distal corpus) and to a lesser degree in the caudal lumen. The 27-kDa protein was distributed all over the equatorial region of the acrosome of less than 10% of caput epididymal sperm. As sperm passed through the corpus epididymis, the percentage of immunoreactive cells increased and the protein was restricted to specific domains of the sperm head. Thus, on the mature sperm, antigen was localized in a crescent-shaped area of the equatorial segment just behind the anterior part of the acrosome and on the apical rim of the sperm head. This is the first observation of a sperm surface antigen derived from an epididymal protein as a proteolytic fragment that interacts with specific regions of the sperm membrane during the process of spermatozoa maturation.

A novel low molecular weight factor detected in the cytosol of guinea pig neutrophils to enhance superoxide anion production

Cytosolic low molecular components in guinea pig neutrophils were examined for the activity to enhance superoxide anion (O2-)-generating NADPH oxidase activity. A component was separated by Sephadex G-25 gel filtration from high molecular weight components, the latter revealed NADPH oxidase activity in a cell-free system in combination with the membrane fraction and arachidonic acid. Addition of this cytosolic low molecular weight component to the cell-free system significantly enhanced NADPH oxidase activity, though this component did not substitute the high molecular weight components in constituting the system. The low molecular weight NADPH oxidase activation factor (LMWAF) found here was not of protein nature, since protease treatment failed to reduce its activity. This factor did not contain phosphate, and was neither flavin nor guanine nucleotide. Though LMWAF was extractable with chloroform-methanol, it was not identical with diacylglycerol.

Transport of digoxin by human P-glycoprotein expressed in a porcine kidney epithelial cell line (LLC-PK1)

This article represents the first evidence that the renal secretion of the commonly used drug, digoxin, is mediated by P-glycoprotein. In this study, it was demonstrated that digoxin is a substrate of P-glycoprotein, and the mechanism of a clinically important drug interaction, such as digoxin-quinidine, was elucidated. Human P-glycoprotein was expressed on the apical membrane of the porcine kidney epithelial cell line, LLC-PK1 by transfecting with human MDR1 cDNA. The expression and function of P-glycoprotein were confirmed by Southern and Western blotting, RNase protection assay, immunostaining and transporting activity for vinblastine. The transepithelial transport of [3H]digoxin was measured across the cell monolayers grown on microporous polycarbonate membrane filters. The transfectant cells exhibited markedly greater basal-to-apical transport and less apical-to-basal transport than the host cells, and the former was 8-fold greater than the latter. The augmented transepithelial transport resulted from the increased efflux from cells to apical side. This oriented transport was inhibited by the presence of 20 microM vinblastine, quinidine or verapamil. The rate of efflux to the apical side was 2-fold greater than that to the basal side. Quinidine inhibited the efflux to the apical side but did not affect transport into the basal side. These findings demonstrate that digoxin is transported by human P-glycoprotein, which is a previously undiscovered drug transport system in the kidney other than organic cation and anion transport systems, and suggest a molecular mechanism for the renal tubular secretion of digoxin as well as clinically important digoxin-quinidine interaction via P-glycoprotein.

Changes in the nature of calcium transport systems on the porcine sperm plasma membrane during epididymal maturation

Comparative studies of 45Ca(2+)-transport across the plasma membrane were performed using porcine caput, corpus and cauda epididymal sperm. The Ca(2+)-uptake is dependent on the presence of the substrates for respiration and is sensitive to verapamil. The Ca(2+)-efflux is mediated by both Na(+)-dependent and -independent systems. In the immature sperm in caput epididymis, Na(+)-independent efflux is predominant, but it is gradually replaced by Na(+)-dependent efflux during the epididymal transit. The net activity of Ca2+ accumulation into sperm increases with the epididymal maturation.

Inhibitory action of dilazep on histamine-stimulated cytosolic Ca2+ increase in cultured human endothelial cells

Using a fluorescent Ca(2+)-sensitive dye, fura-2, and photometric fluorescence microscopy, we measured changes in cytosolic Ca2+ concentration ([Ca2+]i) in cultured human endothelial cells and studied the effect of dilazep on [Ca2+]i elevation induced by histamine. Histamine (1 microM) caused a rapid transient peak in the average [Ca2+]i of a group of cells (approximately 10(2) cells), followed by a decrease to a sustained elevation. Dilazep as well as diltiazem (1.0 to 100 microM) concentration-dependently inhibited the latter sustained elevation, which was eliminated by removal of extracellular Ca2+, while the initial transient response was not changed by dilazep at concentrations up to 100 microM. The IC50 values of dilazep and diltiazem were 16 and 58 microM, respectively. The patterns of the [Ca2+]i elevation responses to histamine were variable among individual cells. Some single cells showed a transient peak and a sustained elevation as observed in a group of cells. Some single cells caused a repetitive spikelike elevation of [Ca2+]i. Dilazep lowered the sustained elevation to the resting level and in some single cells, changed the sustained elevation to the spikelike elevation. The frequency of the spikelike [Ca2+]i elevation was also decreased by dilazep. Decrease in extracellular [Ca2+] showed the same pattern of inhibitory actions as dilazep did. These results indicate that dilazep inhibits the extracellular Ca2+ influx in endothelial cells.

Prostaglandin E1 enhances hepatic portal venous flow by dilating the portal vascular bed in 70% hepatectomized dog

The effects of portal, hepatic arterial and femoral venous administration of prostaglandin E1 (PGE) on portal venous flow (PVF) and hepatic arterial flow HAF were examined before and after 70% hepatectomy in anesthetized dogs. In the hepatectomized condition, portal venous administration of PGE (0.5 microgram/kg/min) caused an increase in PVF without any change in systemic arterial pressure (SAP). HAF was unchanged following the injection. The portal effect of PGE on PVF was dose-dependent, and a reduction in portal venous resistance was seen. However, the same dose of PGE failed to change PVF under intact liver conditions. Hepatic arterial administration of PGE (0.5 microgram/kg/min) brought no significant change in PVF or HAF, with or without hepatectomy. Femoral venous administration of PGE (0.5 micrograms/kg/min) produced an increase in PVF concomitant with a significant decrease in SAP. HAF showed no change after the injection. A decrease in PVR was seen only in the hepatectomized condition. It is concluded that PGE is potent in increasing PVF in the hepatectomized condition, and the portal vasculature is involved as the site of action.

Inflammatory pseudotumor of the spleen. Report of a case with an immunohistochemical study

A 81-year-old Japanese man with a splenic inflammatory pseudotumor is described. The pseudotumor was unchanged in size after one year of observation. Macroscopically, the lesion was a firm well-circumscribed 5.5 x 5 x 5 cm mass showing a yellowish-white cut surface. Histologically, it was composed of abundant mixed inflammatory infiltrates, predominantly UCHL-1(+) T and L26(+) B lymphocytes, plasma cells containing various immunoglobulin subtypes, and S-100 protein(+), and lysozyme and NCA(+) histiocytes, with a sclerotic stroma. Small numbers of eosinophils, neutrophils and foamy macrophages were admixed. The patient has remained disease-free for 14 months after splenectomy. Only ten splenic inflammatory pseudotumors have been reported in the literature. This paper adds an additional case, together with details of immunohistochemical polyclonality of each inflammatory cell population, confirming that this disease is a nonspecific inflammatory change.

Stimulation of superoxide anion production in guinea pig polymorphonuclear leukocytes by hypotonic conditions in combination with protein kinase C activators

Conditions for superoxide anion (O2-) production were examined in guinea pig polymorphonuclear leukocytes (PMNL). When PMNL were suspended in the hypotonic medium, O2- production was significantly enhanced by concurrent treatment with low concentrations of 1-oleoyl-2-acetylglycerol (OAG), a cell-permeable protein kinase C activator. Such hypotonicity or OAG alone had little effect on the production. Other protein kinase C activators also markedly enhanced O2- production in combination with hypotonicity, but not in the isotonic medium. Protein kinase C inhibitors, H-7 and staurosporine, dose-dependently inhibited the production. These observations indicate that protein kinase C participates in such synergistic O2- production with hypotonicity. Phosphorylation of 46-kDa protein(s), which was commonly enhanced in paralleled with an activation of NADPH oxidase in guinea pig PMNL, was increased by treatment with 10 microM OAG, but the phosphorylation was little altered by hypotonic treatment. Intracellular calcium concentration, arachidonate release, and 1,2-diacylglycerol and phosphoinositide concentrations were slightly altered by hypotonic treatment. A change in phosphatidate (PA) production in PMNL was induced by hypotonic treatment either by itself or in combination with OAG treatment. These results suggest that the combination of cell membrane changes by hypotonic treatment accompanied by the increase in PA and 46-kDa protein phosphorylation by protein kinase C provides the conditions required for a marked increase in O2- production. Hypotonicity may be a good tool for studying the mechanism of priming in the activation of NADPH oxidase.

Purification of bicarbonate-sensitive sperm adenylylcyclase by 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid-affinity chromatography

Anion transport inhibitors, such as SITS (4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid) and heparin, inhibit reversibly the bicarbonate-sensitive adenylylcyclase of porcine sperm plasma membrane. In the light of this, SITS- and heparin-affinity chromatographies were applied in order to purify sperm adenylylcyclase. SITS-Affi-Gel 102 binds proteins extracted from the porcine cauda epididymal sperm plasma membrane by Lubrol-PX, more selectively than heparin-agarose. However, recovery of adenylylcyclase activity is higher when heparin-agarose is used. The hormone-sensitive liver adenylylcyclase, which is less sensitive to bicarbonate than sperm enzyme, has less affinity for these affinity resins than sperm enzyme. Adenylylcyclase can be purified to apparent homogeneity on two-dimensional gel electrophoresis (isoelectric focusing/sodium dodecyl sulfate-polyacrylamide gel electrophoresis) from the Lubrol-PX extract of the purified sperm plasma membrane by using SITS-affinity chromatography at the first step of the purification followed by preparative isoelectric focusing and gel filtration. The molecular weight and pI of the purified enzyme are 46,300 and 6.9, respectively. The purified enzyme activity is highly dependent on Mn2+. Bicarbonate activates even the purified enzyme both by decreasing Km and by increasing Vmax.

Gastric acid secretion controlled by oestrogen in women

Gastric acid outputs were measured and related to plasma oestradiol concentrations in women. An inverse relationship between the acid output and the oestradiol concentrations was detected regardless of the stage of the menstrual cycle. It was also noted that the acid output was reduced in a dose-dependent manner after oral administration of conjugated oestrogen and that the response was partially blocked by atropine sulphate. These findings suggest that oestrogen participates in the control of gastric acid secretion in women and that a cholinergic action is involved in the mode of action.

[Enteroinvasive Escherichia coli O121: H- isolated from travellers' diarrhea]

A lactose slow-fermenting, non motile Escherichia coli strain was isolated from a diarrheal patient returning from Indonesia. Examination of virulence of the strain showed that it penetrated into tissue culture cells, and were positive in Serény test and enzyme-linked immunosorbent assay for detection of enteroinvasive E. coli. A large plasmid responsible for virulence was also detected. Thus the strain was confirmed to be a typical enteroinvasive E. coli. Analysis of O serotype using the antisera against E. coli O1-O170 revealed that the strain had O121 antigen, whose antiserum is not included in the commercial serotyping kit for the diagnosis of diarrheagenic E. coli.