[Isolation and identification of an oxygen-tolerant strain of Bifidobacterium from human feces]

This paper reports 136 strains suspected to be species of the genes Bifidobacterium isolated from adult human faeces. Through detection of the ability to tolerate molecular oxygen in cultural environments, we obtained an oxygen-resistant strain TQ21-2-2 according to the Bergy's manual. It was identified as Bifidobacterium longum. A limited number of drinking the beverage, the experiments also using this strain in milk as a starter revealed that this strain has been found useful for treating cases with constipation.

Gamma-IFN induced cell adhesion in chronic myelogenous leukemia cells

Both gamma- and alpha-interferons (IFNs) have been shown to induce clinical responses in chronic myelogenous leukemia (CML). The mechanisms behind these effects are not known. In chronic phase CML, granulocytic progenitors normally found in the bone marrow only, are found extramedullary. A defect in the adhesion of CML cells, that may be responsible for this finding, has been described earlier. In this study, we have investigated whether IFN can restore the defect in CML cell adhesion. It was found that gamma-, but not alpha-IFN, strongly induced the adhesion of CML cells to other cells and to plastic in a majority of the patients. In parallel, an induction in the expression of the adhesion molecules ICAM-1 and LFA-1 was found, and blocking of these molecules by antibodies abolished the effect. The ability of gamma-IFN to restore the adhesive property of CML cells may add to the antitumor effects observed with gamma-IFN therapy in CML.

Role of galanin in stimulation of pituitary luteinizing hormone secretion as revealed by a specific receptor antagonist, galantide

In this study, a specific galanin (GAL) receptor antagonist, galantide, was employed to evaluate the role of endogenous GAL in episodic basal and phasic LH release in rats. To assess the specificity of galantide, a series of experiments was performed. In the first experiment, we observed that administration of GAL (0.62 nm) intracerebroventricularly (icv) in ovarian steroid-primed ovariectomized (ovx) rats rapidly increased plasma LH levels between 10-30 min, and prior injection of galantide icv (5 nm) blocked the GAL-induced LH release. In the second experiment, galantide inhibited the GAL-evoked in vitro release of LHRH from the median eminence-arcuate nucleus (ME-ARC) of ovarian steroid-primed ovx rats. In addition, galantide on its own significantly decreased the basal efflux of LHRH from the ME-ARC of similarly treated rats, thereby suggesting that even the basal LHRH secretion may be a GAL-dependent event. In the third experiment, the effects of galantide on the phasic LH surge elicited by progesterone (P) in estradiol benzoate-primed ovx rats and that occurring spontaneously on proestrus were examined. Ovx rats bearing icv cannulae were primed with estradiol benzoate (30 micrograms/rat, sc) and 2 days later received a P (2 mg/rat, sc) injection at 1000 h to evoke a LH surge in the afternoon. Galantide (1 or 5 nm) in 3 microliters saline or saline was injected icv at 1300, 1400, and 1500 h. The results showed that the two dosages of galantide suppressed the LH surge in the afternoon. On the other hand, only a very high dose of galantide (15 nm) injected iv at 1300, 1400, and 1500 h blunted the P-induced LH hypersecretion. Central injections of galantide (1 or 5 nm) at 1300, 1400, and 1500 h on proestrus also inhibited the preovulatory LH surge and significantly reduced the numbers of rats ovulating the following day. In the final experiment, the role of GAL receptors in modulation of episodic LH release was analyzed in ovx rats. The results showed that an injection of galantide (5 nm, icv) significantly decreased both the mean LH levels and the amplitude of LH episodes during the 3-h observation period. Cumulatively, these results show that normally GAL stimulates LHRH release by activation of a specific receptor located in the ME-ARC, and that GAL may be a key excitatory signal in the hypothalamic neural circuitry involved in the regulation of basal episodic and phasic LHRH secretion in cycling female rats.(ABSTRACT TRUNCATED AT 400 WORDS)

Probing the metal binding sites of Escherichia coli isoleucyl-tRNA synthetase

The metal binding properties of isoleucyl-tRNA synthetase (IleRS) from Escherichia coli were studied by in vivo substitution of the enzyme-bound metals. Purified E. coli IleRS was shown to have two tightly bound zinc atoms per active site. Cobalt- and cadmium-substituted IleRS were also found to contain two tightly bound Co2+ and Cd2+ atoms per polypeptide chain, respectively. The d-d transitions in the low energy absorption spectrum of Co(2+)-substituted IleRS were characteristic of that expected for two tetrahedrally coordinated Co2+ metals. Apo-IleRS was found to be inactive in both the aminoacylation of tRNA(Ile) and in the isoleucine-dependent ATP-pyrophosphate exchange reactions. Both Co(2+)- and Cd(2+)-substituted IleRS were found to have kcat/Km values in the isoleucine-dependent ATP-pyrophosphate exchange assay approximately 5-fold lower than the native Zn2+ enzyme. A single enzyme-bound Zn2+ or Co2+ atom per polypeptide chain could be removed by dialysis of Zn(2+)- or Co(2+)-substituted IleRS against 1,10-phenanthroline. Removal of one of the two enzyme-bound Zn2+ atoms per polypeptide chain with 1,10-phenanthroline was found to decrease (kcat/Km)Ile by approximately 130-fold. The dependence of the kinetic parameters on the identity and number of enzyme-bound metals in the isoleucine-dependent ATP-pyrophosphate exchange reaction suggests that at least one enzyme-bound metal is indirectly involved in aminoacyladenylate formation. Metal substitution or removal of one of the two enzyme-bound metals in IleRS was found to have little effect on the Km value for tRNA(Ile) or the kcat value for aminoacylation of tRNA(Ile).(ABSTRACT TRUNCATED AT 250 WORDS)

Functional expression of a mouse growth hormone receptor cDNA in transfected mouse L cells

A cDNA encoding a full-length mouse (m) growth hormone receptor (GHR) derived from 3T3 F442A cells was amplified by RT-PCR and cloned into a mammalian expression vector. A mouse L cell line (mGHR1.6), which expresses high levels of full-length mGHR, was established. A mGHR-specific mRNA of approx 2.8 kb was found in these cells. Ligand binding studies showed that mGHR 1.6 cells were capable of binding 125I-hGH with a dissociation constant (Kd) of 2.9 +/- 0.13 nM. Scatchard analysis indicated that mGHR1.6 cells had only a single class of mGHR and possessed approx 128,000 GH specific binding sites per cell. Affinity crosslinking studies showed that the recombinant mGHR possessed an apparent molecular mass of 105 kDa. In addition, mGHR1.6 cells responded to growth hormones (GHs) from several species. Two proteins, pp92 and pp95, were found to be tyrosyl phosphorylated following GH treatment. An hGH antagonist, hGH-G120R, inhibited GH-induced phosphorylation of both pp92 and pp95 in a dose-dependent manner. This cell line may be used as an in vitro model in the studies of GH signal transduction and in the screening of GH analogs for biological activity.

Antitumor effect of alpha isomer of anordrin in vitro and cell cycle arrest at G1 phase

Alpha isomer of anordrin (2 alpha, 17 alpha-diethyl-A-norandrostane-2 beta, 17 beta-diol dipropionate, alpha-Ano) inhibited mouse hepatoma (Hep A) and P388 cell growth in vitro. alpha-Ano (20 micrograms.ml-1) inhibited the incorporation of [3H]uridine and [3H]thymidine into RNA and DNA within 3 h, but the inhibition of L-[3H]lysine incorporating into protein was not obvious. alpha-Ano had no effect on the DNA-dependent RNA synthesis with purified nuclei of Hep A cells. It is suggested that the inhibition of RNA and DNA syntheses is the major cause of the cytostatic effect. alpha-Ano blocked the P388 cells at G1/G0 phase, and the delay in G1/G0 to S phase transition plays an important role in the inhibition of P388 cell growth.

Concentrations of cadmium, lead, selenium, and zinc in human blood and seminal plasma

The concentrations of cadmium, lead, selenium, and zinc in blood and seminal plasma were determined in 76 Singapore males. Except for zinc, the concentrations were generally higher in blood than in seminal plasma (cadmium, 1.31 micrograms/L vs 0.61 micrograms/L; lead, 82.6 micrograms/L vs 12.4 micrograms/L, and selenium, 163.6 micrograms/L vs 71.5 micrograms/L). The mean concentration of zinc in seminal plasma was more than 30 times higher than in blood (202 mg/L vs 6.2 mg/L). Significant positive correlations were found between the concentrations in blood and seminal plasma for the two essential trace elements: selenium (r = 0.45, p < 0.001) and zinc (r = 0.25, p < 0.05). However, no relationships were found between the concentrations in blood and seminal plasma for two toxic metals (cadmium and lead). Significant inverse correlations were observed between Cd and Zn (r = -0.40, p < 0.01), and Pb and Se (r = -0.32, p < 0.05) in blood, whereas significant positive correlations were noted between Cd and Se (r = 0.45, p < 0.01), Cd and Zn (r = 0.35, p < 0.05), and Se and Zn (r = 0.57, p < 0.001) in seminal plasma. The physiological significance of these relationships are also discussed in this paper.

Trace elements in blood and seminal plasma and their relationship to sperm quality

The concentrations of cadmium, lead, selenium, and zinc in blood and seminal plasma were determined in 221 Singapore men. The relationship of trace element concentration to sperm density, motility, morphology, and semen volume was also investigated. The concentrations of elements were in the following descending order: Zn > Se > Pb > Cd. Except for zinc, the concentrations were generally higher in blood than in seminal plasma. The mean concentration of zinc in seminal plasma (ZnSP) was about 30 times higher than in blood (ZnB). A significant inverse correlation was observed between blood cadmium levels (CdB) and sperm density (r = -0.24, P < 0.05) in oligozoospermic men (sperm density below 20 million/mL) but not in normospermic men. Cadmium in seminal plasma (CdSP) was also associated with low semen volume (r = -0.29, P < 0.05). These findings suggest that cadmium may have an effect on the male reproductive system. In contrast, positive correlations were observed between concentrations of selenium and zinc in seminal plasma (SeSP and ZnSP) and sperm density in normospermic men but not in oligozoospermic men. The correlation coefficients with sperm density for SeSP and ZnSP were 0.35 (P < 0.05) and 0.41 (P < 0.01), respectively. The concentrations of lead in blood (PbB) or seminal plasma (PbSP) did not appear to have any correlation with the sperm parameters studied.

Inhibition of phosphorylation of histone H1 and H3 induced by 10-hydroxycamptothecin, DNA topoisomerase I inhibitor, in murine ascites hepatoma cells

Hydroxycamptothecin (HCPT), isolated from Camptotheca acuminata, is a powerful antitumor alkaloid. Previous studies indicated that the molecular target of this agent was DNA topoisomerase I. The present results demonstrated that in vitro treatment of murine ascites hepatoma cells with HCPT resulted in a marked reduction in DNA syntheses and the inhibition of phosphorylation in histone was in a time-dependent manner. Gel electrophoresis found that HCPT had a selectively inhibitory effect on the phosphorylation of histone H1 and H3, but less effect on the other kinds of histones. In vivo, HCPT also exhibited a suppressive effect on histone H1 and H3 phosphorylation. These data suggested that HCPT-induced cell killing may be, at least in part, associated with the suppression of histone H1 and H3 phosphorylation.

Identification of the metal ligands and characterization of a putative zinc finger in methionyl-tRNA synthetase

A truncated form of the methionyl-tRNA synthetase (delta MTS), which has been cloned, overproduced, and characterized, was used in an attempt to better understand the role of the enzyme-bound zinc in the amino-acylation process. Apo-, Zn(2+)-, Co(2+)-, and 113Cd(2+)-substituted delta MTS proteins were prepared in vivo and purified to homogeneity. Apo-delta MTS was devoid of enzymatic activity in the aminoacylation of tRNA(fMet) and in the methionine-dependent ATP-pyrophosphate exchange reactions. Kinetic constants in both the aminoacylation and ATP-pyrophosphate exchange reactions for the Co(2+)- and 113Cd(2+)-substituted delta MTS proteins were found to be identical with those of the native Zn2+ protein. The low energy absorption spectrum of Co(2+)-substituted delta MTS resembles the d-d transition bands characteristic of tetrahedrally coordinated Co(2+)-substituted proteins. A strong S-->Co2+ charge transfer absorption at 350 nm was clearly evident having a molar absorptivity consistent with four thiolate ligands. The environment of the metal center was further probed by measuring the 113Cd chemical shift of 113Cd(2+)-substituted delta MTS. A single resonance at 759.6 ppm was observed. This chemical shift is consistent with Cd2+ coordinated to four thiolate ligands. The Escherichia coli methionyl-tRNA synthetase contains a potential metal binding sequence Cys-X2-Cys-X9-Cys-X2-Cys in a connecting polypeptide within the nucleotide fold. Titration of a 21-amino acid peptide corresponding to this putative metal binding site, Cys145-Cys161, was shown to bind Co2+ with a Kd of 120 +/- 11 microM. These results demonstrate that the isolated zinc finger binding domain is capable of specifically forming a stoichiometric complex with the divalent cation. Taken together, our studies identify the 4 cysteine residues in the zinc finger-like domain as the metal binding ligands in the E. coli methionyl-tRNA synthetase. The role of the enzyme-bound metal appears to be structural and not directly involved in catalysis.

Role of neuropeptide-Y in episodic luteinizing hormone release in ovariectomized rats: an excitatory component and opioid involvement

We tested the hypothesis that hypothalamic neuropeptide-Y (NPY) is an excitatory signal in the episodic secretion of LH in ovariectomized (ovx) rats and that the suppression of LH secretion that consistently follows intracerebroventricular administration of NPY is due to concurrent release of opioids or CRH, both previously shown to readily inhibit LH release. In the first experiment, ovx rats received continuous intraventricular infusion of either serum containing NPY antibodies (NPY-Ab) or normal rabbit serum (control) at dilutions of 1:5 or 1:1. NPY-Ab infusion at a 1:5 dilution significantly decreased mean plasma LH levels and LH pulse amplitude without affecting LH pulse frequency over a 3-h period of observation. However, infusion of relatively more concentrated NPY-Ab (1:1) markedly decreased not only mean plasma LH levels and LH pulse amplitude, but also the frequency of LH episodes. In the next experiment, we observed that intraventricular administration of NPY (0.2 nmol) suppressed LH release for 60 min. However, blockade of opiate receptors with iv infusion of naloxone (2 mg/h) before and after NPY injection completely counteracted the NPY-induced inhibition of LH release. On the other hand, prior blockade of the CRH receptors with alpha-helical CRH-(9-41) (25 or 100 micrograms/rat) was ineffective in reversing the inhibitory LH response of NPY (0.125 nmol). These results together with our previous demonstration of morphological communication between NPY and beta-endorphin neurons, show that suppression of LH by exogenous NPY in ovx rats may result from concurrent stimulation of opioids, primarily beta-endorphin. However, diminution of all parameters of episodic LH secretion by NPY-Ab affirms the notion that the NPY network is a physiologically important excitatory component of the hypothalamic pulse generator circuitry that regulates episodic LH secretion in rats.

Arginine vasotocin gene expression and hormone synthesis during ontogeny of the chicken embryo and the newborn chick

Chicken embryos at different developmental stages (embryonal day (E) 6 to 21) and chicks at posthatch day 1 (D1) were monitored for the development of their hypothalamo-neurohypophysial system as indicated by the kinetics of arginine vasotocin (AVT) gene expression via mRNA concentration and brain AVT content. Our data concerning the onset of gene expression support previous results from our laboratory and others about an early activation of the AVT gene transcriptional and translational activity around E6. We could detect measurable amounts of AVT in chicken embryo brains at E6 and an exponential increase during further development until D1. Dot blots of hypothalamic RNA extracts indicated that AVT gene transcript concentrations rose between E12 and E17 and slightly dropped thereafter. Northern hybridization showed that this drop was caused by a decrease of full length message and an increase of smaller transcripts during late embryonal and D1 stages, probably an AVT mRNA specific degradation phenomenon. The dissociation between the increase of AVT concentration and AVT mRNA concentration visible at the D1 stage might be due to accumulation and storage of AVT in the magnocellular neurons, preferentially in their axon terminals in the neurohypophysis. Blood samples taken from E14 onwards revealed a constant increase in plasma osmolality and plasma AVT concentration. Our data suggest that, in the chicken, AVT seems to be required early during embryonal development, either for osmoregulatory or further unknown functions.

Increased pressor responsiveness of femoral arteries to exogenous norepinephrine in renal hypertensive dogs mediated through alpha 2 adrenoceptors

Changes of perfusion pressure induced by femoral arterial perfusion of norepinephrine (NE) were studied in renal hypertensive dogs made with the method of wrapping both kidneys. The NE threshold dose which induced perfusion pressure increase was lower in hypertensive dogs than that in normotensive dogs. The NE pressor response in low concentration (1, 2, 10 ng.kg-1) was increased in hypertensive dogs, after alpha 2 adrenoceptors antagonized by idazoxan this increased response had been eliminated. These suggested that increased vasoconstriction by exogenous NE in hypertensive dogs was mediated through the increased reactivity of postsynaptic alpha 2 adrenoceptors to NE.

[Distribution of 14C labeled at dioxopiperazine or methyl morpholine group of probimane by whole body autoradiography]

Probimane (AT-2153) is a new anticancer compound. It was first developed in this Institute. It is effective against mouse tumors S37, S180, Lewis lung carcinoma, L1210 and human pulmonary adenocarcinoma heterotransplanted into nude mice. In the present work, 14C was labeled at central dioxopiperazine or methyl morpholine group of probimane 120 mg.kg-1 was injected iv in mice bearing Lewis lung carcinoma by whole body autoradiography. The results showed that probimane was broken into at least two parts: a central part and a methyl morpholine group. The central part of compound hardly penetrated through the blood-brain barrier, but accumulated in the urinary bladder. The methyl morpholine group showed a high affinity to tumor tissue and accumulated in spleen, bone and liver.

A human mitochondrial transcriptional activator can functionally replace a yeast mitochondrial HMG-box protein both in vivo and in vitro

Human mitochondrial transcription factor A is a 25-kDa protein that binds immediately upstream of the two major mitochondrial promoters, thereby leading to correct and efficient initiation of transcription. Although the nature of yeast mitochondrial promoters is significantly different from that of human promoters, a potential functional homolog of the human transcriptional activator protein has been previously identified in yeast mitochondria. The importance of the yeast protein in yeast mitochondrial DNA function has been shown by inactivation of its nuclear gene (ABF2) in Saccharomyces cerevisiae cells resulting in loss of mitochondrial DNA. We report here that the nuclear gene for human mitochondrial transcription factor A can be stably expressed in yeast cells devoid of the yeast homolog protein. The human protein is imported efficiently into yeast mitochondria, is processed correctly, and rescues the loss-of-mitochondrial DNA phenotype in a yeast abf2 strain, thus functionally substituting for the yeast protein. Both human and yeast proteins affect yeast mitochondrial transcription initiation in vitro, suggesting that the two proteins may have a common role in this fundamental process.

[A study on classification of Xanthomonas by isoelectric focusing]

Studying Xanthomonas strains of 4 species and 29 pathovars by isoelectric focusing, it was shown that the protein patterns were very different among the species and pathovars. Through cluster analysis of IEF date, it was found that the protein pattern differences among certain pathovars were no fewer than that among the species. It revealed that some pathovars could become to be species. There were few differences of 6 protein bands among X. campestris pv. cerealis, X. campestris pv. undulosa and X. campestris pv. hordei which cause bacterial black cheff, so the classification of the three pathovars need to be re-considered. It also showed that isoelectric focusing could be used to classify Xanthomonas below species.

Cytotoxic effect of interferon on primary malignant tumour cells. Studies in various malignancies

It is a well established fact that interferon (IFN) can inhibit cell growth, but only recently has it been found that IFN can exert a direct cytotoxic effect on primary tumour cells. This was shown in malignant cells from patients with multiple myeloma. In this study the influence of IFN on the viability of primary malignant cells from patients with different malignancies was studied. As previously described a direct cytotoxic effect of IFN on multiple myeloma cells was observed. No major effects on cell viability could be found in malignant cells from patients with lymphoma, chronic lymphocytic leukaemia, hairy cell leukaemia, chronic myelogenous leukaemia and carcinoma. This indicates that the direct cytotoxic effect of IFN in multiple myeloma may be relatively specific for this malignancy. It could be due to a specific differentiation stage in the myeloma cells, specific genetic alterations and/or abrogation of an autocrine/paracrine loop.

[Role of the central alpha-receptors in the modulation of carotid sinus reflex of rats]

To investigate the effects of the central alpha-receptors on the carotid sinus reflex, phenoxybenzamine (PBZ, 2 micrograms/20 microliters) or yohimbine (Y, 2 micrograms/20 microliters) was injected into the lateral cerebral ventricle (LCV) and intracarotid sinus pressure (ISP)-mean arterial pressure (MAP) relationship curve was constructed and fitted by a Logistic function. The results were as follows: (1) After injection of PBZ into LCV, the ISP-MAP relationship curve shifted upward at a higher ISP level with decreased peak slope and MAP range while the ISP-slope curve shifted downward. (2) After injection of Y into LCV, the ISP-MAP relationship curve shifted upward at a higher ISP level with decreased peak slope and MAP range and increased threshold. The ISP-slope curve shifted downward significantly at 10.64, 15.96 kPa. The peak slope and MAP range of Y group decreased significantly as compared with that of the PBZ group. These results indicated that after blockage of central alpha-receptors the sensitivity of the sinus reflex decreased significantly, and the blockage action of alpha 2-receptor is greater than that of alpha 1-receptor.

Baculovirus phosphoprotein pp31 is associated with virogenic stroma

The PstI K fragment of Autographa californica nuclear polyhedrosis virus (AcMNPV) encodes a protein with a molecular weight of 31,000. To define the role of this protein (pp31) in virus infection further, it was overexpressed in bacteria and used to produce polyclonal antiserum. Radioimmunoprecipitation analysis indicated that pp31 was synthesized during both the early and late phases of virus infection, consistent with previous analyses indicating that the gene was regulated by tandem early and late promoters. Metabolic labeling of cells with carrier-free phosphate indicated that pp31 was phosphorylated. Biochemical fractionation experiments showed that pp31 was localized in the nucleus and that it was more stably associated with the nucleus at later times of infection. Immunoblot analysis of subnuclear fractions indicated that pp31 was associated predominantly with the chromatin and nuclear matrix fractions. Immunofluorescence experiments confirmed that the pp31 protein was localized in the nucleus. Nuclear staining was relatively uniform early but was more centrally nuclear later in infection. Immunoelectron microscopy indicated that the pp31 protein was a component of virogenic stroma. Southwestern (DNA-protein) blot analysis demonstrated that pp31 is a DNA-binding protein. These findings suggest a possible role for pp31 in the virus life cycle.