Spinal cord localization of the motoneurons innervating the sacrococcygeus dorsi lateralis muscle and their noradrenergic nerve terminals in rats

We examined in the present study the spinal cord localization of motoneurons innervating the caudal portion of the sacrococcygeus dorsi lateralis (SCDL) muscle and their noradrenergic nerve terminals in Sprague-Dawley rats, using horseradish peroxidase (HRP) and dopamine-beta-hydroxylase (DBH) double-labeling techniques. Retrogradely HRP-labeled motoneurons innervating the caudal part of the SCDL muscle were located ipsilaterally in the ventromedial aspect of the ventral horn (lamina IX) in spinal segments of S2-S4. These cells were polygonal in shape, with an average soma diameter of 37.0 +/- 1.1 microns (mean +/- S.E.M., n = 95) and amounted to 33.6 +/- 5.7 (n = 7) in the horizontal plane. Of note was the presence of abundant DBH-positive nerve terminals arborizing on the soma and dendrites of HRP-labeled motoneurons. These results provided anatomical evidence to further support our previous findings that the coerulospinal noradrenergic neurotransmission is involved in the mediation of fentanyl-induced muscular rigidity.

Unsustained dipsogenic response to chronic central infusion of angiotensin-III in spontaneously hypertensive rats

We evaluated the chronic effect of angiotensin-III (AIII) in the promotion of drinking behavior in spontaneously hypertensive (SH) and normotensive Wistar-Kyoto (WKY) rats, using conscious, freely moving, male, adult animals that had been instrumented with an intracerebroventricular (icv) cannula connected to an osmotic mini-pump for 7-day infusion. Chronic icv infusion of AIII (5 or 10 pmol/min) elicited robust, dose-dependent, and Ile7-AIII (100 pmol/min; as specific antagonist)-reversible dipsogenesis in both SH and WKY rats, with higher water intake in the former strain. However, the drinking response in the SHRs exhibited a sharp drop after 3 days of AIII infusion, during which acute AIII (80 pmol, icv) challenges also failed to induce dipsogenesis. Chronic icv infusion of bestatin (150 pmol/min), an aminopeptidase-B inhibitor, did not by itself discernibly affect basal drinking. When combined with AIII (5 or 10 pmol/min), however, bestatin, respectively, suppressed and augmented the dipsogenic response of SH and WKY rats to the heptapeptide. These results suggest that chronic administration of AIII did not produce sustained drinking behavior in SHRs, possibly because of the development of early desensitization of the angiotensin receptors.

HLA and Singaporean Chinese myasthenia gravis

Chinese Singaporean myasthenia gravis (MG) patients are associated with three HLA haplotypes: Cw1 B46 DRB1*0901 DQB1*0303 DQA1*03, DRB1*14 DRB3*0202 DQB1*0503 DQA1*0101 and DRB1*1202 DRB3*0301 DQB1*0301 DQA1*0601. The B46 haplotype was associated with the total group of MG patients but in particular with those with younger onset, low antiacetylcholine receptor (anti-AchR) titres, with only ocular lesions and with normal thymuses. The DRB1*14 haplotype was associated with thymic hyperplasia, younger onset patients, with high anti-AchR titres and with generalised MG. The DRB1*1202 haplotype was associated with thymoma, older onset patients, ocular lesions, and mid to high anti-AchR titres.

Simultaneous, continuous, on-line and real-time spectral analysis of multiple physiologic signals by a personal-computer-based algorithm

We presented in this communication a computer algorithm that offers the advantage of simultaneous analysis of the power spectrum of multiple physiologic signals, including systemic arterial pressure, single-neuronal and electroencephalographic signals, on a continuous, on-line and real-time basis. It provided sensitive definition, discrimination and quantification (graphic and digital) of the various frequency components in the spectrum. There was also great flexibility in selecting the physiologic signal(s) to be analyzed, the choice of results of analysis to be displayed for each physiologic parameter and the alteration of sensitivity and baseline of each event channel. Furthermore, it included window options to improve the frequency or temporal resolution and discrimination of the spectral changes. Most importantly, all these desirable features can be accomplished economically with a general purpose personal computer.

Reappraisal of the biological role of epidermal growth factor receptor in transitional cell carcinoma

Retrospective immunohistochemical and flow cytometric DNA analyses were performed on 56 cases of transitional cell carcinoma (TCC) to examine the biologic implications of epidermal growth factor receptor (EGFR) expression. A total of 28 (50%) cases were reactive for EGFR immunostaining. The receptor expression increased from 41.7 to 56.3% with tumor stage. There was a significant association between EGFR expression and tumor stage (p < 0.0005), but not tumor grade. The flow DNA content and the Ki-67 proliferating index had no relation to the status of EGFR (p = 1, respectively). For those receptor-positive tumors (n = 28), there was a significant association (p < 0.0001) between receptor expression and tumor proliferation. Interestingly, the DNA content was not correlated with EGFR expression (p = 0.69). We support the possible role of EGFR in cell proliferation and the potential significance for tumor growth in TCCs. However, the biology of TCC in half the cases could not be explained by this mechanism. The interaction between EGFR and DNA ploidy status necessitates further evaluation.

Tonic suppression of baroreceptor reflex response by endogenous neuropeptide Y at the nucleus tractus solitarius of the rat

We evaluated the potential participation of endogenous brain neuropeptide Y (NPY) in central cardiovascular regulation, using adult male Sprague-Dawley rats anesthetized with pentobarbital sodium (40 mg/kg, i.p.). Bilateral microinjection of NPY (4.65 pmol) into the caudal one-third level of the nucleus tractus solitarius (NTS), the terminal site for baroreceptor afferent fibers, promoted a significant suppression of the baroreceptor reflex (BRR) response. The maximal inhibition occurred at 30-40 min postinjection, and amounted to -42.7 +/- 8.6% (mean +/- S.E.M., n = 9). The same treatment, however, only caused transient (approximately 5 min) hypotension and bradycardia. Blocking the endogenous NPY activity at the NTS with its antiserum appreciably enhanced the sensitivity of BRR response (+ 59.2 +/- 18.8%, mean +/- S.E.M., n = 6), but had no appreciable effect on systemic arterial pressure or heart rate. These results suggest that neurons that contain NPY may participate in central cardiovascular regulation by tonically suppressing the BRR response, possibly by exerting an influence on the baroreceptive neurons at the NTS.

Characterization of Mirabilis antiviral protein--a ribosome inactivating protein from Mirabilis jalapa L

A protein was purified from root tubers of Mirabilis jalapa to homogeneity by ion-exchange chromatography on CM-Sepharose CL-6B and FPLC on Mono-S column. The purified protein was confirmed to be Mirabilis antiviral protein (MAP). However, in addition to its antiviral property, the MAP was demonstrated to possess abortifacient activity in pregnant mice, inhibitory effect on cell-free protein synthesis and antiproliferative effect on tumor cells. As judged from its biological and physiochemical properties, MAP is a type I ribosome-inactivating protein.

Identification and cloning of a novel heterogeneous nuclear ribonucleoprotein C-like protein that functions as a transcriptional activator of the hepatitis B virus enhancer II

Liver specificity of hepatitis B virus (HBV) replication has been attributed to the action of its second enhancer (EII). We report here the characterization of EII and the subsequent isolation of a novel liver-specific DNA-binding protein which binds to and activates EII. The cDNA clone of the protein, designated E2BP, was isolated from a lambda gt11 expression library constructed from the hepatoma cell line HuH-6 which was screened with a binding site probe derived from EII. Sequence analysis of E2BP revealed 86.6% homology with a rat heterogeneous nuclear ribonucleoprotein C protein sequence, while conformational studies suggest a helix-loop-helix motif as a DNA-binding site. Cloned E2BP expressed in human fibroblasts by transient transfection displayed EII binding and activating characteristics similar to those of native E2BP in hepatocytes.

Natural killer (NK) cell stimulatory factor or IL-12 has differential effects on the proliferation of TCR-alpha beta+, TCR-gamma delta+ T lymphocytes, and NK cells

We have analyzed the effects of NK cell stimulatory factor/IL-12, on proliferation of PBL and their subsets. IL-12 synergizes with lectins and phorbol diesters to induce proliferation of CD4+ and CD8+ peripheral blood T lymphocytes. In the case of phorbol-diester-induced proliferation, the effect of IL-12 is in part mediated by induced IL-2 production, as suggested by the observation that IL-12 enhances IL-2 production in these cultures and that anti-IL-2 antibodies inhibit proliferation. IL-12 synergizes also with anti-CD3 antibodies and with allogeneic stimulation in MLC in inducing T cell proliferation. IL-12 alone is mitogenic for preactivated T and NK lymphoblasts. This mitogenic effect is observed with similar doses of IL-12 on NK lymphoblasts as well as on CD4+ and CD8+ TCR-alpha beta+ and on TCR-gamma delta+ lymphoblasts. On TCR-alpha beta+ T lymphocytes the effect of IL-12 is always additive to that of IL-2 over a wide dose range. The same effect is observed on highly activated, actively proliferating NK cells. However, on NK and TCR-gamma delta+ lymphoblasts reverting to a resting state after stimulation and on a TCR-gamma delta+ acute leukemia-derived T cell line, IL-12 inhibits significantly the proliferation induced by moderate to high doses (10 to 100 U/ml) of IL-2. This inhibitory effect is, at least in part, indirect, and depends on IL-12-induced production of TNF. Neutralizing anti-TNF antibodies, but not anti-IFN-gamma and anti-transforming growth factor antibodies, restore by more than 70% the inhibition of proliferation induced by IL-12 in these cultures. However, TNF alone cannot mimic the inhibitory effect of IL-12 on the IL-2-induced proliferation of NK and TCR-gamma delta+ lymphoblasts, suggesting the involvement of additional mechanisms. The relevance of these findings for the biology of lymphocyte subsets mediating MHC nonrestricted cytotoxicity is discussed.

Natural killer (NK) cell stimulatory factor or IL-12 has differential effects on the proliferation of TCR-alpha beta+, TCR-gamma delta+ T lymphocytes, and NK cells

We have analyzed the effects of NK cell stimulatory factor/IL-12, on proliferation of PBL and their subsets. IL-12 synergizes with lectins and phorbol diesters to induce proliferation of CD4+ and CD8+ peripheral blood T lymphocytes. In the case of phorbol-diester-induced proliferation, the effect of IL-12 is in part mediated by induced IL-2 production, as suggested by the observation that IL-12 enhances IL-2 production in these cultures and that anti-IL-2 antibodies inhibit proliferation. IL-12 synergizes also with anti-CD3 antibodies and with allogeneic stimulation in MLC in inducing T cell proliferation. IL-12 alone is mitogenic for preactivated T and NK lymphoblasts. This mitogenic effect is observed with similar doses of IL-12 on NK lymphoblasts as well as on CD4+ and CD8+ TCR-alpha beta+ and on TCR-gamma delta+ lymphoblasts. On TCR-alpha beta+ T lymphocytes the effect of IL-12 is always additive to that of IL-2 over a wide dose range. The same effect is observed on highly activated, actively proliferating NK cells. However, on NK and TCR-gamma delta+ lymphoblasts reverting to a resting state after stimulation and on a TCR-gamma delta+ acute leukemia-derived T cell line, IL-12 inhibits significantly the proliferation induced by moderate to high doses (10 to 100 U/ml) of IL-2. This inhibitory effect is, at least in part, indirect, and depends on IL-12-induced production of TNF. Neutralizing anti-TNF antibodies, but not anti-IFN-gamma and anti-transforming growth factor antibodies, restore by more than 70% the inhibition of proliferation induced by IL-12 in these cultures. However, TNF alone cannot mimic the inhibitory effect of IL-12 on the IL-2-induced proliferation of NK and TCR-gamma delta+ lymphoblasts, suggesting the involvement of additional mechanisms. The relevance of these findings for the biology of lymphocyte subsets mediating MHC nonrestricted cytotoxicity is discussed.

Production of natural killer cell stimulatory factor (interleukin 12) by peripheral blood mononuclear cells

Natural killer cell stimulatory factor (NKSF), or interleukin 12 (IL- 12), is a 70-kD heterodimeric cytokine composed of two covalently linked chains, p40 and p35. NKSF/IL-12 has multiple effects on T and NK cells and was originally identified and purified from the supernatant fluid of Epstein-Barr virus (EBV)-transformed human B lymphoblastoid cell lines. We have produced a panel of monoclonal antibodies against both chains of NKSF/IL-12. Some of these antibodies have neutralizing activity, and several combinations of them have been used to establish sensitive radioimmunoassays detecting the free p40 chain, the free p35 chain, or the p70 heterodimer. Using these reagents, we have determined that most EBV-transformed human B lymphoblastoid cell lines constitutively produce low levels of the p70 heterodimer and an excess of the free p40 chain, whereas Burkitt lymphoma-derived, T, myeloid, and many solid tumor-derived cell lines produce neither. Production of both p40 and p70 is increased several-fold upon stimulation of the EBV- transformed cell lines with phorbol diesters. The ability of supernatant fluids from unstimulated and phorbol diester-stimulated cell lines to induce interferon gamma (IFN-gamma) production from T and NK cells, one of the effects of NKSF/IL-12, parallels the levels of production of the p70 heterodimer, known to be the biologically active form of NKSF/IL-12. Staphylococcus aureus Cowan I strain (SAC) and other stimuli induce accumulation of p40 mRNA and production of both p40 and p70 by peripheral blood mononuclear cells (PBMC). The producer cells appear to include both adherent cells and nonadherent lymphocytes, possibly B cells. The supernatant fluids from SAC- stimulated PBMC mediate the typical functions of NKSF/IL-12 (i.e., IFN- gamma induction, mitogenic effects on T/NK blasts, enhancement of NK cell cytotoxicity) at concentrations of p70 similar to those at which recombinant NKSF/IL-12 mediates the same functions. Moreover, these activities are significantly inhibited by anti-NKSF/IL-12 antibodies. The neutralizing anti-NKSF/IL-12 antibodies also inhibit 85% of the IFN- gamma production in response to SAC, an NKSF/IL-12 inducer, and approximately 50% of the IFN-gamma production in response to non- NKSF/IL-12-inducers such as IL-2, phytohemagglutinin, and anti-CD3 antibodies. These results indicate that induced or constitutively produced NKSF/IL-12 has a major role in facilitating IFN-gamma production by peripheral blood lymphocytes.(ABSTRACT TRUNCATED AT 400 WORDS)

Isolation and characterization of COX12, the nuclear gene for a previously unrecognized subunit of Saccharomyces cerevisiae cytochrome c oxidase

We have cloned and sequenced COX12, the nuclear gene for subunit VIb of Saccharomyces cerevisiae cytochrome c oxidase. This subunit, which was previously not found in cytochrome c oxidase purified from S. cerevisiae, has a deduced amino acid sequence which is 41% identical to the sequences of subunits VIb of bovine and human cytochrome c oxidases. The chromosomal copy of COX12 was replaced with a plasmid-derived copy of COX12, in which the coding region for the suspected cytochrome oxidase subunit was replaced with the yeast URA3 gene. The resulting Ura+ deletion strain grew poorly at room temperature and was unable to grow at 37 degrees C on ethanol/glycerol medium, whereas growth was normal at both temperatures on dextrose. This temperature-dependent, petite phenotype of the deletion strain was complemented to wild-type growth with a single copy plasmid carrying COX12. Cytochrome c oxidase activity in mitochondrial membranes from the cox12 deletion strain is decreased to 5-15% of that in membranes from the wild-type parent, and this activity is restored to normal when the cox12 deletion strain is complemented by the plasmid-borne COX12. Optical spectra of mitochondrial membranes from the cox12 deletion strain revealed that optically detectable cytochrome c oxidase is assembled at room temperature and at 37 degrees C, although the heme a + a3 absorption is diminished approximately 50%. The N-terminal amino acid sequence of the protein encoded by COX12 is identical to the N-terminal sequence of a subunit found in yeast cytochrome c oxidase purified by a new procedure (Taanman, J.-W., and Capaldi, R. A. (1992) J. Biol. Chem. 267, 22481-22485). We conclude that COX12 encodes a subunit of yeast cytochrome c oxidase which is essential during assembly for full cytochrome c oxidase activity but apparently can be removed after the oxidase is assembled, with retention of oxidase activity. This is the first instance in which deletion of a subunit of cytochrome c oxidase results in assembly of optically detectable cytochrome c oxidase but having markedly diminished activity.

HLA in Singapore Chinese with rheumatoid arthritis

The HLA-A, B, C, DR and DQ antigens were determined in 50 Singapore Chinese patients with rheumatoid arthritis (RA). There was a significant increase in the prevalence of HLA-Bw46, DRw53 and DQ3 in patients with RA. The linkage disequilibrium between Bw46 and DRw53 explains this association. This major histocompatibility complex association differs from the HLA-DR4 link in Caucasian populations and suggests that RA is an immunogenetically heterogeneous disease.

Extraction, discrimination and analysis of single-neuron signals by a personal-computer-based algorithm

We communicated a computer algorithm that is capable of concurrently extracting, discriminating and analyzing single-neuron signals from adjacent neurons, particularly those with poor signal-to-noise ratio or contaminated by 60-Hz noise and/or baseline drift. Based on a continuous process of differentiation and peak-to-peak amplitude discrimination, our algorithm provided a two-dimensional amplitude histogram that readily distinguishes the clusters of spike signals representing different neurons. The inclusion of a time domain in our three-dimensional amplitude histogram further allowed us to simultaneously evaluate the temporal responses of neighboring cells to the same experimental manipulation. In addition to retaining many of the advanced features of existing extraction and discrimination procedures, this method offered the benefits of being efficient, requires minimal supervision and operates in real time even during long-term recording. Above all, it is cost effective because it is purely software based and only requires a PC-AT compatible general purpose computer.

Inhibition by locus coeruleus on the baroreceptor reflex response in the rat

We evaluated the modulation of baroreceptor reflex (BRR) response by locus coeruleus (LC) in adult, male Sprague-Dawley rats anesthetized with urethane (1.5 g/kg, i.p.). Under an electrical stimulation condition that did not appreciably alter the basal systemic arterial pressure and heart rate, the LC significantly suppressed the BRR response. Microinjection of L-glutamate (1 nmol, 50 nl) into the LC essentially duplicated this depressant effect. Intracerebroventricular (i.c.v.) administration of the alpha 1-adrenoceptor antagonist, prazosin (6.5 nmol), appreciably blunted the inhibition by LC on the BRR response. Yohimbine (6.5 nmol), the alpha 2-adrenoceptor blocker, however, was ineffective. Direct microinjection of prazosin (50 pmol), but not yohimbine (50 pmol), into the terminal site of baroreceptor afferents at the nucleus tractus solitarii (NTS) also significantly blunted the suppressive effect of LC on the BRR response. These results suggest that the LC may produce an inhibition on the BRR response by a process that involves the alpha 1-adrenoceptors located in the NTS.

The thymic compartment responsible for positive selection of CD4+ T cells

Our aim was to assess the generality of the observation that positive selection of CD4+ T cells is mediated by MHC class II molecules on epithelial cells of the thymic cortex. By appropriate matings of previously established transgenic and mutant mouse lines, we were able to produce animals that lacked MHC class II molecules; individuals expressing only the class II E complex, but in all the usual thymic compartments; animals that had E molecules in the thymic medulla but not in the cortex; and, reciprocally, individuals expressing the E complex in the thymic cortex but essentially not in the medulla. Those mice which displayed class II molecules in the cortex had normal numbers of CD4+CD8- T cells in the thymus and CD4+ T cells in the periphery, while 'bare' cortex mice were almost devoid of mature CD4 single positive cells. This finding serves to generalize observations from previous studies of similar design but limited to assaying positive selection of T cells which expressed a single transgenic E-restricted TCR or a subset of V beta 6+ TCRs.

Antigen-specific tachycardia and hypotension in rodents

Tachycardia and hypotension, two cardiovascular responses to anaphylaxis, were specifically induced by antigen in mice and rats, respectively. Intravenous injection of poly (Glu60Ala30Tyr10) (GAT) elicited tachycardia within 30-40 sec in GAT-primed B6 mice. Moreover, a minute amount of GAT (0.2 micrograms) was enough to sensitize the mice to subsequent GAT-induced tachycardia. Challenging doses ranging from 100 ng to 500 micrograms. could elicit tachycardia. The kinetics of tachycardia induction was different from that of antibody production or delayed-type hypersensitivity. Tachycardia was induced from day 6 after immunization, while delayed-type hypersensitivity developed as early as day 4, and anti-GAT antibodies were undetectable on day 6 and would not reach a maximum until day 8. Specific antigen-induced hypotension was also observed in rats. Furthermore, cardiovascular changes in both species could be passively transferred by heat-treated (56 degrees C, 30 min) sera from immunized animals. These benchmarks of antigen-induced cardiovascular changes in mice or rats could be used as models to study the immune control of cardiovascular changes in anaphylactic responses.

Elicitation of penile erection following activation of the hippocampal formation in the rat

We explore the possible involvement of the hippocampal formation in penile erection, using male, adult Sprague-Dawley rats that were anesthetized with pentobarbital sodium. The intracavernous pressure (ICP) was used as the experimental index for penile erection. Electrical activation of the hippocampal formation resulted in two patterns, viz, multiple and single episodes of elevation in ICP, along with visible penile erection and ejaculation. The former pattern exhibited an increase in ICP that was more sustained, with higher peak amplitude and longer latency. Furthermore, they originated respectively from the granule cells of the dentate gyrus and pyramidal cells of the CA1 and CA3 fields of the Ammon's horn. Chemical stimulation of the hippocampus with glutamate also elicited significant increase in ICP. These results thus provided direct evidence to establish that the hippocampal formation may be involved in central neural regulation of the erectile process.

[Mannitol reduces plasma hydrogen peroxide free radical in patients undergoing coronary artery bypass graft surgery]

During the procedure of coronary artery bypass graft surgery (CABG), the release of free oxygen radicals as a result of ischemia and reperfusion which plants the seeds of post-operative low cardiac output and arrhythmias has grave consequence on the reestablishment of cardiac function. A variety of chemical agents such as mannitol, allopurinol, catalase (Q-10) and superoxide dismutase (SOD) has proved to be considerably effective to improve the myocardial necrosis following ischemia and reperfusion. In this study we chose mannitol (0.2 gm/kg) as the free oxygen radicals scavenger and utilized mass spectrophotometric method to detect the variation of concentration of [H2O2], a by-product of free oxygen radical, in an attempt to evaluate the efficacy of mannitol in this regard in patients undergoing CABG. Patients were divided into experimental group (n = 19) and control group (n = 20). In the experimental group the concentration of [H2O2] changed from 61 +/- 24 microM/L pre-operatively to 77 +/- 18 microM/L post-operatively as against 75 +/- 31 microM/L and 99 +/- 31 microM/L respectively in the control group. In comparison, only the change in experimental group was statistically significant (p less than 0.05). We confirmed that mannitol functions considerably as a free oxygen radical scavenger since it reduces the production of [H2O2] in patients undergoing CABG.

Intracavernous pressure as an experimental index in a rat model for the evaluation of penile erection

This report communicates our attempt to design a small animal model for the evaluation of penile erection, based on the pharmacological responses of cavernous tissues in the rat that resemble those of human subjects. Male adult Sprague-Dawley rats anesthetized with pentobarbital sodium were used in conjunction with papaverine and prostaglandin E1, two vasoactive drugs most commonly used in clinical management of impotence. Intracavernous administration of papaverine (0.05, 0.1, 0.02, 0.4 or 0.8 mg.) induced a progressive increase in intracavernous pressure that peaked at 0.4 mg. This effect was associated with visible penile erection that became conspicuous when accompanied by additional bursts of transient intracavernous pressure fluctuations. The duration of papaverine-induced increase in intracavernous pressure was significantly shortened by clonidine (15 micrograms, intracavernous). Injection of prostaglandin E1 (1, 2 or 4 micrograms) into the corpus cavernosum also elicited an elevation in intracavernous pressure, but the responses exhibited acute tachyphylaxis. By manifesting a response to papaverine and prostaglandin E1 that is similar to that in human, we conclude that the intracavernous pressure in the rat may represent a suitable index for the evaluation of penile erection in small laboratory animals.

Participation of pertussis toxin-sensitive GTP-binding regulatory proteins in the suppression of baroreceptor reflex by neurotensin in the rat

We evaluated the molecular mechanism that may underlie the suppressive effect of neurotensin (NT) on the baroreceptor reflex (BRR), using Sprague-Dawley rats that were anesthetized with sodium pentobarbital (50 mg/kg, i.p.). Intracerebroventricular (i.c.v.) application of NT (15 nmol) significantly inhibited the BRR response. Such an inhibition was appreciably antagonized by pretreating animals with i.c.v. injection of pertussis toxin (10 or 20 pmol), N-ethylmaleimide (1 or 2 nmol), forskolin (30 or 60 nmol) or phorbol 12-myristate 13-acetate (2 or 4 nmol), but not by cholera toxin (15 or 30 pmol). More specifically, pretreatments with bilateral microinjection into the nucleus tractus solitarius (NTS) of pertussis toxin (80 or 160 fmol), N-ethylmaleimide (80 pmol), forskolin (480 pmol) or phorbol 12-myristate 13-acetate (16 or 32 pmol) also blunted the NT-induced suppression of BRR, although cholera toxin (120 or 240 fmol), or 1,9-dideoxyforskolin (480 pmol) had no appreciable effect. These results suggest that a pertussis toxin-sensitive guanine nucleotide-binding regulatory protein(s), which is not likely to be Gs, possibly Gi or Gp, may be involved in the transmembrane signaling process that underlies the suppression of BRR response by NT at the NTS.

Recombinant DNA hepatitis B vaccine containing Pre-S components of the HBV coat protein--a preliminary study on immunogenicity

A novel recombinant hepatitis B vaccine, trademarked Sci-B-Vac, was evaluated for safety, tolerability and immunogenicity in an open label trial performed in Singapore. The experimental vaccine, derived from Chinese hamster ovary (CHO) cells, consists of hepatitis B surface antigen (HBsAg) particles harbouring all three viral envelope polypeptides, the major S protein and the minor Pre-S2 and Pre-S1, in their glycosylated and non-glycosylated forms. The vaccine was administered intramuscularly at 0, 1 and 6 months. No unexpected adverse effects were observed. A high level anti-HBs response to Sci-B-Vac was indicative of its immunogenicity. Subsequent to the third injection, 100% and 92% of the 10 micrograms and 5 micrograms dose recipients, respectively, were seroprotected (anti-HBs titres greater than or equal to 10 mIU ml-1). Moreover, the geometric mean titres (GMT) of the anti-HBs response were very high: 2687 and 1473 mIU ml-1, respectively. An immunogenic advantage of Sci-B-Vac was also suggested by the rapid onset of antibody response: 96% of the 10 micrograms dose recipients were seroprotected with a GMT of 159 mIU ml-1, prior to the third injection.

Reversal by pertussis toxin and N-ethylmaleimide of the facilitation of baroreceptor reflex response by somatostatin in the rat

We evaluated the transmembrane signaling mechanism that may underlie the facilitatory action of somatostatin (SOM) on baroreceptor reflex (BRR), using adult, male, Sprague-Dawley rats anesthetized with pentobarbital sodium (40 mg/kg, i.p.). Intracerebroventricular (i.c.v.) application of SOM (2 nmol) promoted a significant elevation in BRR response, induced by phenylephrine (5 micrograms/kg, i.v.). This potentiatory action of the tetradecapeptide was significantly reversed after pretreating animals with bilateral microinjection of pertussis toxin (25 ng) or N-ethylmaleimide (2 nmol) into the nucleus tractus solitarius (NTS), the terminal site for baroreceptor afferents. These results suggest that a pertussis toxin-sensitive GTP-binding regulatory protein, possibly Gi, may be involved in the modulation of the BRR by SOM at the NTS.

Mechanisms of IFN-gamma induction by natural killer cell stimulatory factor (NKSF/IL-12). Role of transcription and mRNA stability in the synergistic interaction between NKSF and IL-2

We have investigated the molecular mechanisms regulating IFN-gamma production in human T lymphocytes stimulated by NK cell stimulatory factor (NKSF/IL-12). We show that NKSF synergizes with IL-2 and phorbol diesters inducing the accumulation of IFN-gamma mRNA in PHA-activated T cell blasts. NKSF regulates IFN-gamma mRNA expression in PHA blasts and the T leukemia cell line, TALL-103/2, at both the transcriptional and posttranscriptional levels. NKSF increases the transcriptional rate for IFN-gamma in both these cell types, as determined by nuclear run-on analysis. However, synergy between NKSF and IL-2 can be demonstrated only at the level of mRNA stability, and both cytokines are required to increase IFN-gamma mRNA half-life.