Clinical significance of quantitative analysis of carcinoembryonic antigen assessed by flow cytometry in fresh human gastric cancer cells

The expression of carcinoembryonic antigen(CEA) on tumor cells freshly excised from 51 patients with gastric cancer was studied using flow cytometry. The expression of CEA by flow cytometry was more quantitative than that by immunohistochemical staining. There was no relationship between the fluorescence intensity assessed by flow cytometry and serum CEA levels, except for patients with a high titer of serum CEA. The patients with high grade CEA expression on tumor cells by flow cytometry had poor prognoses, compared to patients with low CEA expression in undifferentiated gastric cancer. Thus, it is suggested that the quantitative CEA expression on tumor cells by flow cytometry could be a useful prognostic marker in postoperative gastric cancer patients.

Three-dimensional board-to-board free-space optical interconnects and their application to the prototype multiprocessor system: COSINE-III

A prototype multiprocessor system using three-dimensional board-to-board free-space optical interconnects is constructed for the first time to our knowledge. In the system, 64 processing units form a three-dimensional mesh processor network with the help of bidirectional board-to-board free-space optical interconnects. A theoretical analysis shows that the three-dimensional board-to-board freespace optical interconnects effectively solve common interconnection problems such as wiring congestion, signal delay, and clock skew. The prototype system, COSINE-III, is confirmed to work well as a multiprocessor system. The system is also shown to be easy to extend to a larger and more flexible system.

Localization of myogenin, c-fos, c-jun, and muscle-specific gene mRNAs in regenerating rat skeletal muscle

It has been suggested that myogenin is an important factor for the differentiation of myoblasts and that its function in myogenesis is regulated by proto-oncogenes in in vitro experiments. We have characterized the spatial and temporal expression patterns of myogenin, c-fos, c-jun, and muscle creatine kinase mRNAs during the skeletal muscle regeneration process using in situ hybridization histochemistry. Myogenin transcripts are first detected in the myonuclei/nuclei of satellite cells at 6 h after induction of regeneration. Myogenin mRNA is expressed in desmin-positive myoblasts, yet no muscle creatine kinase mRNA is detected in this cell type. Both the muscle creatine kinase and myogenin mRNAs are expressed in the newly formed myotubes, but not at earlier stages. Transcripts for c-fos and c-jun mRNAs are expressed first in the myonuclei/nuclei of satellite cells at 3 h post-trauma. c-jun mRNA is expressed in both myoblasts and myotubes, while c-fos mRNA was not detected in these cells. These results suggest that myogenin plays important role in the regeneration of injured muscle and that c-jun and c-fos may have different roles in this process.

Generation of CD4+ cytotoxic T lymphocytes stimulated by immobilized anti-CD3 monoclonal antibody and interleukin-2 in cancer patients

The proliferation of autologous tumor-reactive cytotoxic T lymphocytes (CTL), induced by autologous mixed lymphocyte tumor-cell culture, was remarkably enhanced by activation with immobilized anti-CD3 monoclonal antibody (MAb) and interleukin-2 (IL-2), as compared with IL-2 alone. The activated CTL exhibited high cytotoxicity against autologous tumor cells. Cytotoxicity against autologous tumor cells was inhibited by anti-HLA-DR MAb. In negative selection with immunomagnetic beads, cytotoxicity against autologous tumor cells was inhibited by the elimination of CD4+ cells. The major cell-surface antigens of the activated CTL were CD3+, CD4+, CD25+, CD45RO+ and CD45RA-, suggesting helper T cells, and the activated CTL produced IL-2. It is concluded that the CTL activated by immobilized anti-CD3 MAb and IL-2 were CD4 cells that had both killer and helper functions. Our findings indicate that adoptive immunotherapy using these activated CTL would be effective in cancer patients.

Novel antitumor indolocarbazole compound 6-N-formylamino-12,13-dihydro-1,11- dihydroxy-13-(beta-D-glucopyranosyl)-5H-indolo[2,3-a]pyrrolo[3,4- c]carbazole-5,7(6H)-dione (NB-506): induction of topoisomerase I-mediated DNA cleavage and mechanisms of cell line-selective cytotoxicity

A new indolocarbazole antitumor agent, NB-506 [6-N-formylamino-12,13-dihydro-1,11-dihydroxy-13-(beta-D-glucopyranosyl) -5H- indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione], enhanced the DNA cleavage catalyzed by HeLa S3 topoisomerase I at 0.01 microM but not the cleavage by topoisomerase II at 300 microM. It also caused single-strand DNA breakage in intact cells at 0.08 microM and more. Unlike the known topoisomerase I inhibitor camptothecin, NB-506 intercalated with DNA. However, the binding affinity to DNA and the inhibition against DNA polymerase alpha and RNA polymerase II were marginal compared with those of Adriamycin or actinomycin D. NB-506 inhibited the growth of various tumor cell lines at two micromoles or less, and its cytotoxicity was found to be cell line selective. This selective cytotoxicity of NB-506 was not fully explained by the differences in topoisomerase I activity in these cell lines, but there was some relationship between the amount of NB-506 accumulated in these cell lines and its cytotoxicity toward them. In conclusion, NB-506 is a potent topoisomerase I poison, acting selectively on tumor cell lines accumulating NB-506.

Polysaccharide preparation PSK augments the proliferation and cytotoxicity of tumor-infiltrating lymphocytes in vitro

We have investigated whether or not polysaccharide preparation PSK directly augments the proliferation and cytotoxicity of tumor-infiltrating lymphocytes (TILs). TILs were separated from 10 patients with gastrointestinal cancer (5 gastric cancers, 3 colon cancers and 2 pancreatic cancers). TILs were cultured with IL-2 and PSK for 7 days. The DNA synthesis of TILs was augmented by incubation with 100 micrograms/ml of PSK, which was similar to serum level with oral administration of PSK in cancer patients. The effect of PSK in DNA synthesis was also found by elimination of non-T cells. Furthermore, we established TIL clones and examined the effect of PSK on TILs clones. The DNA synthesis was augmented by PSK in CD4 positive and CD8 positive TIL clones without non-T cells, suggesting that PSK acts directly on TILs. We examined the cytotoxic activities of TILs by the 4-h and 16-h 51Cr release assay. PSK did not affect the cytotoxic activity of TILs against autologous tumor cells and KATO-III cells in the 4h 51Cr release assay, whereas PSK induced high lysability of TILs against autologous tumor cells in the 16-h 51Cr release assay. We studied the ability of PSK to induce cytokines from TILs using a double chamber plate. The DNA synthesis of tumor cells was more suppressed by the mixed-tumor cell culture supernatants of TILs cultured with PSK, compared to that of TILs cultured without PSK. It is suggesting that PSK induced long term killing activity of TILs by induction of cytotoxic cytokines. Thus, PSK augmented the proliferative response of TILs without interaction of T cells and non-T cells and induced cytotoxic cytokines of TILs.

Inhibition by differentiation-inducing agents of wild-type p53-dependent apoptosis in HL-60 cells

The product of the p53 tumor-suppressor gene has been shown to function in apoptosis and cell cycle regulation. However, there is little information regarding the regulation of apoptosis in cell differentiation. We investigated the relationship between p53-dependent apoptosis and differentiation induction using human promyelocytic leukemia HL-60 cells transfected with pMAMneo expression vectors containing dexamethasone-inducible wild-type p53 (wt-p53) cDNA inserts. Continuous exposure of the pMAMneo/wt-p53 transfectants to 1 microM dexamethasone for more than 24 h caused overexpression of wt-p53 followed by cell death with morphological changes typical of apoptosis. Using the wt-p53-inducible HL-60 cells, we examined the effects of differentiation inducers on the wt-p53-dependent apoptosis. All-trans retinoic acid (all-trans RA) at 1 nM or granulocyte macrophage colony-stimulating factor (GM-CSF) at 35 pM inhibited the wt-p53-induced apoptosis over a 42-h treatment. The apoptosis inhibition by GM-CSF, but not all-trans RA, was abolished by specific inhibitors of protein kinase C. These results suggest that extracellular signals involved in the differentiation induction could modulate the wt-p53-dependent apoptosis through protein kinase C-dependent and independent pathways.

Functional domains of Pho81p, an inhibitor of Pho85p protein kinase, in the transduction pathway of Pi signals in Saccharomyces cerevisiae

The PHO81 gene is thought to encode an inhibitor of the negative regulators (Pho80p and Pho85p) in the phosphatase (PHO) regulon. Transcription of PHO81 is regulated by Pi signals through the same PHO regulatory system. Elimination of the PHO81 promoter or its substitution by the GAL1 promoter revealed that stimulation of the PHO regulatory system requires both increased transcription of PHO81 and a Pi starvation signal. The predicted Pho81p protein contains 1,179 amino acids (aa) and has six repeats of an ankyrin-like sequence in its central region. The minimum amino acid sequence required for Pho81p function was narrowed down to a 141-aa segment (aa 584 to 724), which contains the fifth and sixth repeats of the ankyrin-like motif. The third to sixth repeats of the ankyrin-like motif of Pho81p have significant similarities to that of p16INK4, which inhibits activity of the human cyclin D-CDK4 kinase complex. Deletion analyses revealed that the N- and C-terminal regions of Pho81p behave as negative and positive regulatory domains, respectively, for the minimal 141-aa region. The negative regulatory activity of the N-terminal domain was antagonized by a C-terminal segment of Pho81p supplied in trans. All four known classes of PHO81c mutations that show repressible acid phosphatase activity in high-Pi medium affect the N-terminal half of Pho81p. An in vitro assay showed that a glutathione S-transferase-Pho81p fusion protein inhibits the Pho85p protein kinase. Association of Pho81p with Pho85p or with the Pho80p-Pho85p complex was demonstrated by the two-hybrid system.

Myocardial action potential prolongation by calcium channel activation under calcium free-EGTA condition in rats: developmental and regional variations

1. Prolongation of action potentials upon the addition of isoproterenol, forskolin, isobutylmethyl-xanthine (IBMX) and dibutyril cAMP (dbcAMP) under Ca-free EGTA condition was examined in isolated myocardial preparations from neonatal and adult rats, whose action potential configuration greatly differ. 2. The prolongation of the action potential was previously suggested to be produced by persistent sodium influx through calcium channel due to the lack of calcium-mediated inactivation of calcium channels under such experimental condition. 3. Preparations used were papillary muscles and free walls of the right and left ventricles from neonatal and adult rats. 4. In adult preparations, the prolongation produced by isoproterenol, forskolin and IBMX in the right free wall was smaller than those in the other three regions, while no regional difference was observed with dbcAMP. 5. The degree of prolongation by all of the four drugs were smaller in the neonate than in the adult. No regional difference was observed with any of the drugs in the neonate. 6. Our present results suggest that contribution of calcium-mediated inactivation of calcium channels to the repolarization of rat myocardium may increase postnatally to produce the developmental shortening of its action potential. Also, regional difference in the cAMP related mechanisms may appear postnatally.

Unusual widening of Virchow-Robin spaces: MR appearance

MR in two patients with unusual widening of the Virchow-Robin spaces showed multiple cystic foci up to 2 cm in diameter along the perforating medullary arteries in the cerebral white matter, mainly in one cerebral hemisphere. These areas were of the same signal intensity as cerebrospinal fluid on all pulse sequences. In one patient, the cystic foci in the white matter were biopsied and histologically confirmed to be large Virchow-Robin spaces.

Augmentation of specific tumor killing activity by tumor-infiltrating lymphocytes (TIL) in the presence of TNF-SAM2

The effect of TNF-SAM2 on cytotoxic activity of tumor-infiltrating lymphocytes (TIL) was investigated. TIL were prepared from 11 human cancer patients. They were propagated by double in vitro stimulation with anti-CD3 monoclonal antibody and interleukin-2, and cultured for 3 weeks. The cytotoxic activity of TIL was tested with standard 4h 51Cr-release assays in the presence or the absence of TNF-SAM2. In the presence of TNF-SAM2 (500U/ml), the mean cytotoxic activity against autologous tumor cells was significantly augmented compared to that in its absence. However, the fact that cytotoxic activity against K562 and Daudi showed no difference whether substance was present or not, indicates that LAK and NK activity were not affected by TNF-SAM2. Direct cytotoxicity by exogenously added TNF-SAM2 to tumor cells was measured in 9 out of 11 cases and this revealed that cytotoxicity solely by TNF-SAM2 was seen in 3 tumors. However, there was no correlation between the augmentation of cytotoxicity by TIL in the presence of TNF-SAM2 and the cytotoxicity shown by TNF-SAM2 alone. These results suggested that TIL therapy combined with administration of exogenous TNF may exert a synergistically stronger therapeutic effect on cancer.

Significant role of 5 alpha-reductase on feedback effects of androgen in rat anterior pituitary cells demonstrated with a nonsteroidal 5 alpha-reductase inhibitor ONO-3805

A 5 alpha-reductase inhibitor with nonsteroidal structure, ONO-3805, has been used to study the role of 5 alpha-reductase on positive and negative feedback effects of androgen on gonadotropin secretion in the rat anterior pituitary gland. Initially, the potential of ONO-3805 to inhibit the formation of 5 alpha-dihydrotestosterone (DHT) was evaluated. The activity of 5 alpha-reductase in rat anterior pituitary gland was approximately one-fourth of that in rat prostate gland or epididymis, with a Michaelis' constant (Km) value for testosterone of 5-6 x 10(-7) M. When homogenates of rat anterior pituitary glands were incubated with 14C-testosterone (14C-T) in the presence of > or = 10(-7) M ONO-3805, the formation of labeled DHT and its metabolite 5 alpha-androstane-3 alpha,17 beta-diol was inhibited by > 90%. The inhibition pattern was non-competitive, and the inhibition constant (Ki value) derived from Lineweaver-Burk plots was 3.9 x 10(-11) M. Dispersed pituitary cells (1-2 x 10(5)/ml) were cultured for 48 hours and then further incubated with or without androgen and/or the inhibitor for 72 hours (basal secretion). After this incubation, the media were saved, and 10 nM of luteinizing hormone-releasing hormone (LH-RH) with the same concentration of androgen and/or the inhibitor as used in the 72-hour incubation was added to the cultures for 6 hours (LH-RH-induced secretion). Secreted follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were assayed by radioimmunoassay (RIA). Both testosterone (T) and DHT stimulated 72-hour basal FSH secretion from cultured pituitary cells in a dose-dependent fashion.(ABSTRACT TRUNCATED AT 250 WORDS)

MR of acute subarachnoid hemorrhage: a preliminary report of fluid-attenuated inversion-recovery pulse sequences

We report preliminary results applying fluid-attenuated inversion-recovery (FLAIR) sequences to three patients with acute subarachnoid hemorrhage. Acute subarachnoid hemorrhage could be clearly demonstrated as areas of high signal intensity on FLAIR sequences in all patients. These preliminary results suggest that with FLAIR sequences one could reliably diagnose acute subarachnoid hemorrhage.

Haemodynamic and haematologic effects of Acanthaster planci venom in dogs

This study was designed to examine haemodynamic and haematologic effects of the crown-of-thorns starfish venom (Acanthaster planci venom: APV) in dogs. Severe systemic hypotension, thrombocytopenia and leukopenia were induced by APV (1.0 mg protein/kg i.v.), followed by gradual return to the baseline level within 60 min. Hypotension was presumably caused by two factors: an early decrease in systemic vascular resistance and the large reduction in cardiac output due to reduced ventricular filling. Indomethacin, a cyclooxygenase inhibitor, remarkably suppressed systemic hypotension induced by APV. The peak reduction in systemic pressure was associated with concomitant rise of plasma 6-keto-PGF1 alpha, a major stable metabolite of prostacyclin. Thus, the hypotensive effect of APV may be caused primarily by prostacyclin and/or some vasodilating prostaglandins. In contrast, thrombocytopenia and leukopenia were not affected by cyclooxygenase inhibitor, 5-lipoxygenase inhibitor or platelet activating factor (PAF) receptor antagonist. When APV was administered repeatedly, tachyphylaxis was developed in haemodynamic effects, but not in haematologic effects. These findings suggest that APV-induced hypotensive effects may occur mainly through endogenous production of vasodilating prostaglandins including prostacyclin, although APV-induced thrombocytopenia and leukopenia may be caused by other mechanism(s) unrelated to arachidonate metabolites and/or PAF.

Ultrastructure of the intracellular membranous system of rat hepatocytes in intrahepatic cholestasis induced by phalloidin

To investigate the effect of a thickened pericanalicular ectoplasm in tubulovesicular transport and biliary excretion, we examined the ultrastructure of the intracellular membranous system in rat hepatocytes with and without phalloidin treatment, by transmission electron microscopy and scanning electron microscopy combined with the Aldehyde prefix Osmium-Dimethyl Sulfoxide-Osmium method. Hepatocytes possessed elaborate networks of tubules around bile canaliculi, and some of them extended to the bile canaliculi in control rats. Vesicles were also present around the bile canaliculus. Treatment of rats with phalloidin produced a thick pericanalicular ectoplasm around the bile canaliculus visualized by transmission electron microscopy, and the density of vesicles (p < 0.001) and tubules (p < 0.001) within 0.5 microns around the bile canaliculus significantly decreased in phalloidin-treated rats. The number of lysosomes in hepatocytes apparently increased in phalloidin-treated rats; however, they were rarely observed around the bile canaliculus. The Aldehyde prefix Osmium-Dimethyl Sulfoxide-Osmium method produced an organelle-free space around the bile canaliculus by removing the thick pericanalicular ectoplasm in scanning electron microscopic examination, and the thickened pericanalicular ectoplasm inhibited the approach of intracellular membranes to the canalicular membrane in the transmission electron microscopic examination. In some pathological cholestatic conditions, the thickened pericanalicular ectoplasm may inhibit not only bile canalicular contraction but also biliary excretion of substances, which is mediated by the tubulovesicular transport system.

Evaluation of the long-lasting antihypertensive action of 7-O-ethylfangchinoline

The antihypertensive effect of 7-O-ethylfangchinoline (TJN-220) was analyzed in an experimental model of hypertensive rats under the conscious condition. Single oral administration of TJN-220 (25 and 50 mg/kg) produced a progressive and long-lasting fall of mean blood pressure in spontaneously hypertensive rats (SHRs), deoxycorticosterone acetate (DOCA)-salt hypertensive rats and renal hypertensive rats until 72 hr after the drug administration, but affected neither the heart rate in these hypertensive rats nor the hemodynamic parameters in normotensive rats. In SHRs implanted with a telemetry transmitter, TJN-220 (50 mg/kg, p.o.) produced falls of systolic and diastolic blood pressures and diminished the difference in blood pressure between the dark period and the light period for 3 days, particularly by suppressing the increasing phase of blood pressure during the dark period without influencing heart rate or locomotor activity. On the other hand, nicardipine (10 mg/kg, p.o.) produced a transient fall of blood pressure associated with a tachycardia during the light period on the first day alone. Clonidine (0.3 mg/kg, p.o.) diminished the increasing phases of blood pressure and heart rate during the dark period on the first day alone. Thus, the antihypertensive action of TJN-220 was much longer than those of nicardipine and clonidine. The present results suggest that TJN-220 may have potential for use as a beneficial antihypertensive drug.

Differential expression of fos family and jun family mRNAs in the rat hypothalamo-pituitary-adrenal axis after immobilization stress

We aimed to clarify the regulatory mechanism of the hypothalamo-pituitary-adrenal axis that plays key roles in initiating stress responses, as well as the roles of immediate early genes in this process. We investigated the stress-induced activation of fos and jun family proto-oncogenes by means of in situ hybridization histochemistry. Immobilization stress induced c-fos and jun B mRNAs in the parvocellular region of the hypothalamic paraventricular nucleus, the anterior and intermediate lobes of pituitary, and in the adrenal gland after 7 min of immobilization, although no c-fos or jun B mRNAs were detected in these and other organs in control rats. The levels of these mRNAs peaked after 30-60 min of immobilization, then declined. A low level of fos B mRNA appeared at 15-30 min and peaked after 60-90 min. On the contrary, c-jun and jun D mRNAs were constitutively expressed in the paraventricular nucleus and adrenal cortex. These findings indicate that the members of the fos and jun family proto-oncogenes play different roles in the transcriptional regulation of genes involved in the hypothalamo-pituitary-adrenal axis, and that monitoring immediate early genes is a useful method for following stress-induced cellular responses in the neuro-endocrine system.

In vitro augmentation of cytotoxic activity of peripheral blood lymphocytes and spleen cells of cancer patients by ubenimex

Ubenimex is used for the immunotherapy of malignant diseases as a biological response modifier (BRM) and shows beneficial effects as an adjuvant treatment. In the present study, the in vitro effects of ubenimex on the cytotoxic activity of peripheral blood lymphocytes (PBL) and spleen cells of cancer patients and the mechanism of killer cell activation were investigated. Cytotoxic activity against K562, KATO-III and autologous tumor cells was augmented by in vitro sensitization with ubenimex (p < 0.05). The optimal concentration of ubenimex for induction of cytotoxic activity was 1 micrograms/ml, similar to serum levels after clinical oral administration. The major population of killer cells activated by ubenimex recognizing K562 was CD16+, and those recognizing KATO-III were mainly CDA+ or CD8(5) cels and CD16+ NK cells, while CDA5 or CD8+T cells comprised the majority of killer cells which showed autologous tumor-killing activity. Augmentation of the cytotoxic activity of mononuclear cells by ubenimex was blocked by both anti-IL-1 beta Ab and anti-IL-2 AB. However, the expression of IL-2 receptor (p55, p75) on effector cells was not altered. Ubenimex augmented not only NK activity but also autologous tumor killing activity of PBL and spleen cells via macrophage activation. These activities of ubenimex may be clinically beneficial as an adjuvant treatment.

Ubenimex treatment enhances the susceptibility of gastric cancer cell lines to lymphokine-activated killer cells

We investigated the direct effects of ubenimex on the modification of gastric carcinoma cell lines' susceptibility to killer cells, and the mechanism of its action. The susceptibility of both MKN-45 cells and KATO-III cells to LAK cells was enhanced by treatment with ubenimex for 48 h (p < 0.05), and the optimal concentration for this effect was 10 micrograms/ml. The susceptibility of ubenimex treated KATO-III cells to CD3+ LAK cells, especially to those also expressing CD8, was enhanced. DNA synthesis of tumor cells was not impaired by treatment with ubenimex at all concentrations tested. The binding rate of LAK cells and ubenimex-treated KATO-III cells was similar to that between LAK cells and untreated KATO-III cells. Moreover, no alterations in the expression of any antigen related to mononuclear cell-binding to tumor cells were induced by ubenimex. Lysis or the inhibition of DNA synthesis of tumor cells by LAK cell supernatant was enhanced by ubenimex. These results suggested that the mechanism responsible for the augmentation of tumor cell susceptibility by ubenimex may be a result of the alteration of their sensitivity to some Iytic factors released by LAK cells. Thus ubenimex shows not only an indirect host-mediated anti-tumor activity but also a direct effect on tumor cells, modifying their susceptibility to killer cells, and this may explain why ubenimex shows beneficial clinical effects as an adjuvant treatment.

Effect of mixed live vaccine (Newcastle disease and infectious bronchitis) and Mycoplasma gallisepticum on the chicken respiratory tract and on Escherichia coli infection

Interaction between mixed live vaccine (Newcastle disease and infectious bronchitis), Mycoplasma gallisepticum (MG) and Escherichia coli (EC) was studied in specific-pathogen-free chickens, aged 7 days, inoculated intranasally. In the tracheas of chickens inoculated with vaccine, MG and EC, profuse multiplication of EC occurred together with severe and persisent histological lesions, and some birds died from EC infection. Similar though less dramatic effects occurred in birds that received vaccine and EC. The tracheas of chickens inoculated with the vaccine alone, or with MG and EC, or with MG alone, showed comparatively mild effects. There were no histological lesions in the tracheas of chickens inoculated with EC alone. This study suggests that the field use of mixed live vaccine in flocks infected with MG may induce EC septicaemia.

Inhibitory effect of vapiprost on contractile responses of isolated dog renal arteries to thromboxane A2 analogue, U46619

1. Cumulative administrations of U46619, a thromboxane A2 analogue, and prostaglandin (PG) F2 alpha produced concentration-dependent contractions of isolated dog renal arterial preparations, which were significantly and concentration-dependently inhibited by vapiprost. 2. A bolus administration of U46619 or PGF2 alpha produced sustained contracture of these preparations, which was concentration-dependently relaxed by cumulative vapiprost. 3. Results indicate that vapiprost inhibits U46619- and PGF2 alpha-induced dog renal arterial contractions through antagonism for so-called TP receptors.

Transcriptional attenuation and differential mRNA stability in the regulation of the Escherichia coli melibiose operon

The organization of the melibiose operon of Escherichia coli is promoter-melA-melB. The amount of the product (alpha-galactosidase) of the first gene (melA) is much larger than that of the product (melibiose permease) of the second gene (melB). Using the chloramphenicol acetyltransferase gene (cat) as reporter, we found that there was an element between melA and melB, which reduced the expression of the downstream gene, melB. This region contained a boxA-like sequence, which is known as a binding site for an attenuation factor, NusA. Northern hybridization analysis revealed that the ratio of melA mRNA and melAB mRNA was comparable with the ratio of the melA and melB products. We also found that the melA mRNA was about 3-fold more stable than the melAB mRNA. Experimental results obtained with a nusAts mutant suggested that the NusA protein is involved in the reduced expression of the melB gene. We conclude that the production ratio of alpha-galactosidase and melibiose permease is regulated at two levels: 1) transcription and 2) mRNA stability.

[Clinical effect of arbekacin on MRSA infections after gastrointestinal surgery]

From January 1991 to July 1993, 58 patients with MRSA infections in our clinic at Wakayama Medical College and six affiliated hospitals were administered with arbekacin (ABK). The clinical results were as follows: 1. The clinical efficacy rates of ABK were 84% in pneumonia, 100% in both wound infections and hepatobiliary tract infections, and 85% in total. The bacteriological efficacy rate was 83%. 2. Regarding the administration route, the clinical efficacy rates were 60-79% by the intravenous treatment and inhalation therapy. Especially by the local administration with ABK, MRSA was eradicated in all cases. 3. The sufficient efficacy was obtained by the treatment of ABK alone (89%) and by the combined treatment with ABK (82%) and another antibiotics. From these results, it is concluded that ABK is useful for the treatment of MRSA infections after gastrointestinal surgery.

Biochemical and pharmacological profile of a potent and selective endothelin B-receptor antagonist, BQ-788

We describe the characteristics of a potent and selective endothelin (ET) B-receptor antagonist, BQ-788 [N-cis-2,6-dimethylpiperidinocarbonyl-L-gamma-methylleucyl-D -1- methoxycarbonyltryptophanyl-D-norleucine]. In vitro, this compound potently and competitively inhibits 125I-labeled endothelin 1 (ET-1) binding to ETB receptors on human Girardi heart cells (IC50, 1.2 nM) but only poorly inhibits the binding to ETA receptors on human neuroblastoma cell line SK-N-MC cells (IC50, 1300 nM). In isolated rabbit pulmonary arteries, BQ-788 shows no agonist activity up to 10 microM and competitively antagonizes the vasoconstriction induced by an ETB-selective agonist, BQ-3020 (pA2, 8.4). In rat, an ETA-selective antagonist, BQ-123 (1 mg/kg, i.v.), does not affect transient depressor response to ET-1 (0.3 nmol/kg, i.v.) but potently inhibits following sustained pressor response; vice versa, BQ-788 (1 mg/kg, i.v.) abolishes the depressor response, resulting in a rapid onset of apparently enhanced pressor response. Thus, being a potent and selective ETB receptor antagonist, BQ-788 may be considered as a powerful tool for investigating the role of ET in physiological and pathological processes.