Alpha 1-adrenoceptor subtype involved in the positive and negative inotropic responses to phenylephrine in rat papillary muscle

1. In rat papillary muscle, stimulation of alpha 1-adrenoceptors results in a biphasic inotropic response: a transient negative inotropic phase and a subsequent sustained positive inotropic phase. This study was designed to determine whether the positive and negative inotropic effects in this tissue are mediated by different alpha 1-adrenoceptor subtypes. 2. After treatment with the tumor-promoting compound, phorbol 12, 13-dibutyrate, phenylephrine (in the presence of propranolol) produced only a positive inotropic effect. The selective alpha 1A-adrenoceptor antagonist, WB4101, significantly inhibited the positive inotropic effect. In contrast, inactivation of alpha 1B-adrenoceptors with chloroethylclonidine (CEC) did not alter the positive effect. 3. In the presence of the Ca2+ channel antagonist, nifedipine, phenylephrine induced only a sustained negative inotropic effect. The negative inotropic effect was significantly attenuated by WB4101, but was not affected by CEC. 4. We conclude that both the positive and negative inotropic responses of rat papillary muscle to phenylephrine are mediated exclusively by the WB4101-sensitive but CEC-resistant alpha 1-adrenoceptor subtype. The alpha 1-adrenoceptor subtype with such a property may correspond to the alpha 1A-subtype.

Analysis of heart rate variability demonstrates effects of development on vagal modulation of heart rate in healthy children

OBJECTIVES

Analysis of heart rate variability (HRV) has been found to be a useful method of assessing cardiovascular autonomic control, but normal values for standard HRV measures in children have not been established. We analyzed HRV in 60 healthy children aged 3 to 15 years to determine normal values and to assess the effects of development on cardiac autonomic control with the use of ambulatory electrocardiographic monitoring.

RESULTS

The high-frequency (HF) component, an index of cardiac autonomic tone, increased significantly with age from 3 to 6 years (p < 0.01) and decreased with age from 6 to 15 years (p < 0.01), and the magnitude of HF correlated significantly with the R-R intervals. Thus the changes in cardiac autonomic tone could be described as a simple equation using age and heart rate.

CONCLUSIONS

We present normal values and changes in the cardiac autonomic system during childhood after HRV analysis, which could lead to a better understanding and treatment of cardiac disease in children.

[Reproducibility of spasm in patients with long-term remission of vasospastic angina by medical treatment]

The reproducibility of coronary vasospasm was assessed in nine patients with complete remission of vasospastic angina by medical treatment by reexamination at intervals of mean [+/-SD] 5.7 +/- 0.9 years. Twenty-one segments were defined as spastic, demonstrating more than 90% narrowing after acetylcholine injection at the initial angiography. The degree of spasticity, type of spasm (diffuse or focal) and coronary artery diameter in these segments at the initial and follow-up studies were compared. Of the 21 segments, 17 (81%) still had some spasticity (> 25%) at the follow-up study and 8 (38%) of these 17 showed spasticity with greater than 90% narrowing. On the other hand, spasm was not reprovoked in 4 (19%) segments. Luminal diameter of the spastic segments decreased significantly at the follow-up study (2.52 +/- 0.83 vs 2.26 +/- 0.62 mm, p = 0.01), but percentage stenosis was not different between the initial and follow-up studies (9.1 +/- 7.2 vs 10.3 +/- 8.0%, NS). The reproducibility of the type of spasm provoked was 83%. Coronary vasospasticity persists to some extent in spite of complete remission of angina by medical treatment, and the type of spasm provoked has high reproducibility. Therefore, the cessation of drug treatment should be done carefully.

FHIT mutations in human primary gastric cancer

Allelic deletion of multiple regions on the short arm of chromosome 3 (3p) implies the presence of multiple important tumor suppressor genes in human carcinogenesis. The FHIT gene, identified recently in chromosome 3p14.2, shows frequent allelic deletion and aberrant transcripts in gastrointestinal tumors. After determining the intron sequences flanking each of the coding exons of the FHIT gene and designing intron primers to facilitate mutation analysis of genomic DNA samples, we analyzed the complete coding sequences in matched cancer and normal tissues from 40 cases with primary gastric cancer using intron primers, PCR-single-strand conformation polymorphism analysis, and direct sequencing. A somatic missense mutation in exon 6, codon 61, ACG (threonine) --> ATG (methionine) was found in a signet ring cell adenocarcinoma. We also evaluated allelic deletion in these tumors by PCR-based microsatellite analysis; allelic deletion occurred in 42.1% (16 of 38) of evaluable cases. This is the first report of a somatic missense mutation of the FHIT gene in a primary tumor. Presence of a point mutation and frequent allelic deletions are consistent with the hypothesis that FHIT gene alterations are involved in the development of primary gastric cancers.

Mutation analysis of coding sequences of the entire transforming growth factor beta type II receptor gene in sporadic human colon cancer using genomic DNA and intron primers

Mutations in the transforming growth factor beta type II receptor (TGFbeta RII) gene have been detected in several human cancers exhibiting microsatellite instability. To extend analyses of this gene, we previously investigated the exon-intron organization of the TGFbeta RII gene and defined seven exons and flanking intron sequences. In this study, we further determined the nucleotide sequences surrounding these seven exons and designed eight sets of intron-based primers to examine the entire coding region of the TGFbeta RII gene. Using these primers, we screened genomic DNA sequences from 30 sporadic colorectal cancers for mutations of the TGFbeta RII gene. TGFbeta RII mutations were detected in two of 30 tumors and both displayed microsatellite instability. One had a deletion in a polyadenine tract in exon 3 and the other had a point mutation in the kinase domain located in exon 7. There were no mutations in exons 1, 2, 4, 5 and 6. These results further implicate the polyadenine tract and kinase domain as mutational hotspots in the TGFbeta RII gene in cells with genomic instability and suggest that TGFbeta RII gene mutations occur rarely in cells lacking genomic instability.

Presence of human cellular protein(s) that specifically binds and cleaves 8-hydroxyguanine containing DNA

8-hydroxyguanine (oh8Gua) is a major form of oxygen free radical-induced DNA damage. The oh8Gua nucleotide can pair with cytosine (C) and adenine (A) nucleotides which can cause G:C to T:A transversions. It is known that multiple repair systems for the correction of the oh8Gua exist in both mammalian and bacterial cells. Using the technique of gel mobility shift assay, protein(s) bound to the oh8Gua:C base pair in short fragments of DNA was detected in cell-free extracts of a human small-cell lung cancer cell line. This DNA binding activity was specific, since it was poorly detected with an unmodified G:C base pair containing oligonucleotide duplex and was affected by neither the unmodified G:C base pair nor an oh8Gua:A base pair containing oligonucleotide duplex. The partially purified protein which selectively binds to the oh8Gua:C base pair was shown by gel filtration column chromatography to have an apparent molecular mass of 52 kDa. The column fraction which showed the highest binding activity to the oh8Gua:C base pair was found to possess an enzymatic activity that specifically cleaves the oh8Gua containing oligonucleotide strand at both the 5' and 3' sides of the oh8Gua residue. These results indicate the presence of a protein(s) that is involved in a DNA repair pathway for the correction of the oh8Gua residue in human cells.

Lung carcinogenesis and formation of 8-hydroxy-deoxyguanosine in mice by diesel exhaust particles

In order to clarify the involvement of oxygen radicals in lung carcinogenesis induced by diesel exhaust particles (DEP), the relationship between lung tumour response and formation of 8-hydroxydeoxyguanosine (8-OHdG) in lung DNA was examined. The role of high dietary fat and beta-carotene on these responses was also studied. Mice were intratracheally injected with 0.05, 0.1 and 0.2 mg of DEP per animal once weekly for 10 weeks. After 12 months, the lung tumour incidence in mice treated with 0.05 mg and 0.1 mg showed similar increases (30% and 31%), but was decreased to 24% at 0.2 mg. High dietary fat enhanced the incidence of both benign and malignant tumours. beta-carotene partially prevented the tumour development. After the 10 weekly treatments of DEP, inflammatory reaction was observed in the respiratory tract and alveoli. The formation of 8-OHdG in lung DNA from mice treated with DEP showed a dose dependent increase. 8-OHdG formation was enhanced by high dietary fat and partially reduced by beta-carotene. Formation of 8-OHdG was significantly correlated with the lung tumour incidence except at 0.2 mg. These results suggest that the induction of oxidative DNA damage may be an important factor in the initiation of DEP-induced lung carcinogenesis, and that beta-carotene and high dietary fat may play a role in the regulation of tumour development via modulation of the formation of 8-OHdG.

Oxygen uptake efficiency slope: a new index of cardiorespiratory functional reserve derived from the relation between oxygen uptake and minute ventilation during incremental exercise

OBJECTIVES

We investigated the usefulness of a new variable, oxygen uptake efficiency slope (OUES), as a submaximal measure of cardiorespiratory functional reserve. The OUES is derived from the relation between oxygen uptake (Vo2 [ml/min]) and minute ventilation (VE [liters/min]) during incremental exercise and is determined by VO2 = a log VE + b, where a = OUES, which shows the effectiveness of Vo2.

BACKGROUND

Maximal oxygen uptake (VO2max) is effort dependent. There is no standard submaximal measurement of cardiorespiratory reserve that provides generally acceptable results.

METHODS

Exercise tests, following a standard Bruce protocol, were performed on a treadmill by 108 patients with heart disease and 36 normal volunteers. Expired gas was continuously analyzed. The OUES was calculated from data of the first 75%, 90% and 100% of exercise duration. We also determined the following submaximal variables: the ventilatory anaerobic threshold (VAT), the slope of the regression line of the minute ventilation-carbon dioxide production relation (VE-VCO2 slope) and the extrapolated maximal oxygen consumption (EMOC). We analyzed the relation of OUES and other submaximal variables against VO2max and examined the effects of submaximal exercise on OUES.

RESULTS

The correlation coefficient of the logarithmic curve-fitting model was 0.978 +/- 0.016 (mean +/- SD). The OUES and VO2max had a significant correlation (r = 0.941, p < 0.0001). The correlation between VO2max and OUES was stronger than that between VO2max and VAT, the VE-VCO2 slope or EMOC. The OUES values for 100% and 90% of exercise were not different from each other (at an alpha value of 0.05 and treatment effect of 170, the power of the test [1-beta] was 0.90); OUES for 75% of exercise was slightly lower (3.5%).

CONCLUSIONS

Our results suggest that OUES may provide an objective, effort-independent estimation of cardiorespiratory functional reserve that is related both to pulmonary dead space and to metabolic acidosis.

Exercise-induced ventricular tachycardia without demonstrable heart disease in childhood

Exercise-induced ventricular tachycardia (VT) without demonstrable heart disease was studied in pediatric patients. The study population consisted of 17 patients aged 5-14 years (average 9.1 years), who demonstrated reproducible VT during or immediately after exercise testing using a treadmill. The main reasons for the exercise testing were episodes of exercise-related syncope in two patients, exercise-related palpitation in seven and evaluation of sporadic ventricular premature contraction (VPC) in eight. Of the eight patients in the asymptomatic group, two developed sustained VT and the other six had non-sustained VT. Of the nine patients in the symptomatic group, six developed sustained VT. Verapamil produced a good response in seven of 14 patients, and propranolol in six. None of the patients died during the follow-up period, an average of 59.6 months. In four patients, both VT and VPC disappeared, not only on exercise testing, but also on Holter electro-cardiograms, so the anti-arrhythmic agents were discontinued. One patient had syncope and convulsion caused by rapid bidirectional VT in the follow-up period. It was concluded that the prognosis of exercise-induced VT without demonstrable heart disease in children is relatively benign, but careful follow-up is required.

Direct evidence for antipseudomonal activity of macrolides: exposure-dependent bactericidal activity and inhibition of protein synthesis by erythromycin, clarithromycin, and azithromycin

Several previous investigators have reported that long-term administration of certain macrolides is efficacious in patients with persistent pulmonary Pseudomonas aeruginosa infections, even though the clinically achievable concentrations of these medications are far below their MICs. In the present study, we examined how sub-MICs of macrolide antibiotics affect the viability of and protein synthesis in several strains of P. aeruginosa. We report that 48 h, but not 12 or 24 h, of growth on agar containing a clinically achievable concentration of azithromycin (0.5 microgram/ml, 1/128 the MIC) significantly reduces the viability of strain PAO-1. Similar effects were seen with erythromycin and clarithromycin at 2 micrograms/ml (1/128 and 1/64 the respective MICs), whereas josamycin, oleandomycin, ceftazidime, tobramycin, minocycline, and ofloxacin had no effect on viability, even following 48 h of incubation with concentrations representing relatively high fractions of their MICs. The bactericidal activity of azithromycin seen following 48 h of incubation was not limited to strain PAO-1 but was also seen against 13 of 14 clinical isolates, including both mucoid and nonmucoid strains. Although viability was not decreased prior to 48 h, we found that 4 micrograms of azithromycin per ml inhibits protein synthesis after as little as 12 h and that protein synthesis continues to decrease in a time-dependent manner. We likewise found that P. aeruginosa accumulates azithromycin intracellulary over the period from 12 to 36 h. These results suggested that sub-MICs of certain macrolides are bactericidal to P. aeruginosa when the bacteria are exposed to these antibiotics for longer periods. Exposure-dependent intracellular accumulation of the antibiotic and inhibition of protein synthesis may partially account for the antipseudomonal activity of macrolides over relatively prolonged incubation periods.

Alpha 1-adrenoceptor subtypes mediating inotropic and electrophysiological effects in mammalian myocardium

Stimulation of alpha 1-adrenoceptors produces a positive inotropic effect in rat and rabbit ventricular myocardium via different mechanisms, the prolongation of action potential duration (APD) exclusively in the former and an increase in myofibrillar Ca2+ sensitivity in large part in the latter. This study was designed to determine whether the two inotropic mechanisms are mediated by different alpha 1-adrenoceptor subtypes. In rat papillary muscles, the positive inotropic effect and APD prolongation induced by phenylephrine (in the presence of propranolol) were inhibited by WB-4101, but not affected by chlorethylclonidine (CEC). WB-4101, but not CEC, blocked the phenylephrine-induced inhibition of the transient outward current (Ito) in rat ventricular cells. On the other hand, WB-4101 and CEC each antagonized the positive inotropic effect of phenylephrine in rabbit papillary muscles. However, the phenylephrine-induced APD prolongation observed in rabbit papillary muscles was blocked only by WB-4101. These results indicate that the WB-4101 sensitive alpha 1-adrenoceptor subtype mediates the positive inotropism that is correlated with the APD prolongation resulting from Ito reduction, whereas the CEC-sensitive subtype mediates the positive inotropism that is probably associated with increased myofibrillar Ca2+ sensitivity. Radioligand binding studies with [3H] prazosin showed a similar ratio of alpha 1A-to alpha 1B-adrenoceptor subtypes in rat and rabbit ventricular myocardium, implying that the different degree of contribution of each action mechanism to the overall inotropic effect in the two species cannot be explained by distribution of the alpha 1-adrenoceptor subtypes.

The new muscarinic M1-receptor agonist YM796 evokes yawning and increases oxytocin secretion from the posterior pituitary gland in rats

The present experiments were performed to examine the effects of a new muscarinic M1-receptor agonist, (-)-YM796 ((-)-S-2,8-dimethyl-3-methylene-1-oxa-8-azaspiro[4.5]decane L-tartrate monohydrate), on yawning and oxytocin secretion from the posterior pituitary gland in rats YM796, at doses of 2.5-50 mg/kg (SC), elicited yawning. The yawning response was markedly increased by pretreatment with a beta-adrenoceptor antagonist, pindolol (20 mg/kg, IP), which per se did not elicit yawning. The yawning induced by YM796 (10 mg/kg, SC) in combination with pindolol (20 mg/kg, IP) was inhibited by scopolamine (0.5 mg/kg, SC), a muscarinic receptor antagonist, and pirenzcpine (300 micrograms/ rat, ICV) and EEDQ (N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline) (5 mg/kg, IP), muscarinic M1-receptor antagonists, but not by spiperone (0.5 mg/kg, SC), a dopamine D2-receptor antagonist, 4-DAMP (4-diphenylacetoxy-N-methylpiperidine methiodide) (100 micrograms/rat, ICV), a muscarinic M3-receptor antagonist, and [d(CH2)5, Tyr(Mc)2, Orn8]-vasotocin (100 ng/rat, ICV), an oxytocin receptor antagonist. YM796 at 2.5-50 mg/kg (SC) did not exert an action on prolactin levels but increased oxytocin secretion from the posterior pituitary gland in rats. This augmentation of oxytocin secretion by YM796 was inhibited by scopolamine (0.5 mg/kg, SC) and pirenzepine (3 mg/kg, SC), but not by mecamylamine (1 mg/kg, IP), a nicotinic receptor antagonist. The present findings obtained with YM796 suggest that the muscarinic M2-receptor stimulation participates in causing yawning behavior and oxytocin secretion in rats.

The genomic structure of the gene encoding the human transforming growth factor beta type II receptor (TGF-beta RII)

The genomic structure of the human transforming growth factor-beta type II receptor gene (TGF-beta RII) was determined by two PCR-based methods, the "long distance sequencer" method and the "promoter finder" method. Genomic fragments containing exons and adjacent introns were amplified by PCR, and the nucleotide sequences were determined by direct sequencing and subcloning sequencing. The TGF-beta RII protein is encoded by 567 codons in 7 exons. This is the first report about the genomic structure of a gene that belongs to the serine/threonine kinase type II receptor subfamily. Knowledge of the genomic structure of the TGF-beta RII gene will facilitate investigation of the TGF-beta signaling pathway in normal human cells and of the aberrations occurring during carcinogenesis.

Alpha 1-adrenoceptor subtype distribution and the coupling to phosphoinositide hydrolysis in rat and rabbit ventricular myocardium

The relative contributions of the alpha 1A- and alpha 1B-adrenoceptor subtypes to the stimulation of phosphoinositide (PI) hydrolysis in rat and rabbit ventricular myocardium were defined pharmacologically using WB-4101 and chloroethylclonidine (CEC). Radioligand binding experiments with [3H]prazosin showed that the maximum number of alpha 1A-adrenoceptors in rat myocardium was about ten times higher than in rabbit myocardium. The proportion of the two [3H]prazosin binding sites with high and low affinity for WB-4101 was similar in the two species: approximately 30% of the alpha 1-adrenoceptor population was pharmacologically alpha 1A and approximately 70% was alpha 1B. Phenylephrine produced concentration-dependent stimulation of PI hydrolysis in rat ventricular strips as measured by [3H]inositol monophosphate accumulation, but this stimulation was much less in rabbit. In both of the two species, WB-4101 was very effective in inhibiting phenylephrine-stimulated PI hydrolysis, whereas CEC had a minimal effect. Altogether, the degree of PI hydrolysis appears to be determined by the density of myocardial alpha 1-adrenoceptors. However, despite the greater density of the alpha 1B-subtype, it is the alpha 1A-subtype that is mainly coupled to PI hydrolysis in mammalian myocardium.

RAGE and amyloid-beta peptide neurotoxicity in Alzheimer's disease

Amyloid-beta peptide is central to the pathology of Alzheimer's disease, because it is neurotoxic--directly by inducing oxidant stress, and indirectly by activating microglia. A specific cell-surface acceptor site that could focus its effects on target cells has been postulated but not identified. Here we present evidence that the 'receptor for advanced glycation end products' (RAGE) is such a receptor, and that it mediates effects of the peptide on neurons and microglia. Increased expressing of RAGE in Alzheimer's disease brain indicates that it is relevant to the pathogenesis of neuronal dysfunction and death.

Immunosuppressive acidic protein (IAP) level in serum and peritoneal washings, and its implication in determining multidisciplinary treatments

In this study we examined the efficacy of the measurement of IAP (serum ancl peritoneal washings) during the treatment of colorectal cancers, and determined the possible benefits of using the IAP measurements from both serum and peritoneal washings. One hundred and six patients (peritoneal washings: 58, peritoneal fluid: 67) were investigated. Serum IAP levels were significantly higher in patients who underwent complicated surgical procedures which involved greater time and blood loss compared to those patients who underwent less involved surgical procedures with little loss of blood and time. In peritoneal washings, up to 66. 7% of cases with peritoneal dissemination showed elevated levels of IAP in the peritoneal cavity, while 37% of cases with no dissemination at surgery macroscopically had positive IAP levels (8 mg/g protein). The results suggest the value of IAP in determining the need for combined immunochemotherapy for patients in an immunosuppressive environment.

Nodular cutaneous lupus mucinosis: report of a case and review of previously reported cases

A wide variety of cutaneous manifestations of lupus erythematosus have been reported. Among them, papulonodular eruptions produced by dermal mucin deposition have been recognized as nodular cutaneous lupus mucinosis (NCLM), and many cases have been reported in Japan. A 21-year-old woman with systemic lupus erythematosus (SLE) showed papulonodular eruptions on her back. A skin specimen from the nodule revealed mucin deposition (hyaluronic acid) in the dermis. NCLM should be recognized as a clinical form associated with SLE. The pathogenesis of the mucin deposition in NCLM is still uncertain.

Unitary current through the inward rectifier K+ channel cloned from rabbit heart--comparison with the native K+ channel

Recently, we have cloned a cDNA for a putative cardiac inward rectifier K+ channel (RBHIK1) from rabbit cardiac muscles. However, it's single channel characteristics have remained unknown. Therefore, we investigated the single channel characteristics of the RBHIK1 channel expressed in Xenopus oocytes by the cell attached patch clamp configuration, and compared them with those of the native Ik1 channel of the freshly-isolated ventricular myocytes under similar temperature conditions. In patch clamp experiments with 145 mmol/l K+ in the pipette at room temperature (20-22 degrees C), both the RBHIK1 currents and the native Ik1 showed a strong inward rectifying property. The single channel conductance of the RBHIK1 channel was 17.8 +/- 0.47 pS (n = 4), and that of the native Ik1 channel was 23.5 +/- 0.29 pS (n = 5). The activities of the cloned channel were sensitive to the putative K+ channel blockers (TEA, Cs+ and Ba2+). The open and closed time histograms at -140 mV could be fitted by a single exponential both in the RBHIK1 channel and the native Ik1 channel. Although the closed-time histogram of the native Ik1 channel was fitted by a sum of two exponential curves, that of the RBHIK1 channel was fitted by a single exponential curve. The sublevel corresponding to two-thirds of the unitary current was observed both in the RBHIK1 channel and the native Ik1, but it was more frequently detected in the RBHIK1 channel. Amplitude histogram constructed at -140mV in the RBHIK1 channel exhibited three peaks, which indicated closed, full-open, and 2/3 sublevel state, respectively. Unitary current was calculated to be 2.5 pA and sublevel of the unitary current was 1.68 pA. These characterization in the single channel activities of the RBHIK1 channel will help to study the molecular regulation of the Ik1 channel in cardiac cells.

Epidemiology of bacterial meningitis in children: Aichi Prefecture, Japan, 1984-1993

The details of 328 patients with bacterial meningitis, admitted from 1984 through 1993, were obtained from 46 departments of pediatrics of large hospitals through questionnaires. The incidence rate per 100,000 child-years was 2.32, being higher in children aged 0-4 years (rate, 7.22) than 5-15 years (rate, 0.49). The disease in the 274 (84%) etiologically diagnosed patients was due to Haemophilus influenzae (95), Streptococcus pneumoniae (56), Group B streptococci (GBS) (41), Escherichia coli (27), and other agents (55), including 7 patients with Mycobacterium tuberculosis infection. The short-term outcome (mean length of follow-up, 2 years, 11 months) of meningitis was death in 26 patients (8.2%) and sequelae in 49 (16.0%), including 26 children with multiple residual impairment. Tuberculous, pneumococcal, and GBS meningitis with a poor outcome increased during the late period (1989-1993) of the 10-year study. The annual infant mortality rate for purulent meningitis decreased from 3.7 to 1.4 per 100,000 population between 1984 and 1993. The incidence of a poor outcome (death and sequelae) in newborns decreased by half during the late period.

Partial agonistic effects of OPC-14597, a potential antipsychotic agent, on yawning behavior in rats

The present experiments were performed to examine the behavioral effects of OPC-14597, which acts on dopamine receptors in rats. OPC-14597 administered subcutaneously (SC) at doses of 0.1-5 mg/kg elicited yawning, as did OPC-4392 (0.5-2 mg/kg, SC) and (-)-3-PPP (2.5-10 mg/kg, SC). These yawning responses were blocked by intraperitoneal (IP) pretreatment with haloperidol (0.5 mg/kg) but were increased by pindolol (20 mg/kg, IP) or reserpine (5 mg/kg, IP), which per se did not elicit yawning. The yawning induced by talipexole, a selective dopamine D2 receptor agonist, was inhibited by OPC-14597 (0.5-5 mg/kg, SC) and (-)-3-PPP (10 mg/kg, SC). Apomorphine (0.5 mg/kg, SC), a dopamine D1/D2 receptor agonist, elicited stereotypy such as sniffing and licking but OPC-14597 (5-20 mg/kg, SC) did not induce this behavior. The stereotypy induced by apomorphine was inhibited not only by haloperidol (0.5 mg/kg, IP) and (-)-3-PPP (10 mg/kg, SC) but also by OPC-14597 (5-20 mg/kg, SC), without being affected by OPC-4392 (2 mg/kg, SC). In 6-hydroxydopamine (6-OHDA)-treated rats, apomorphine (0.5 mg/kg, SC) elicited rotation behavior whereas OPC-14597, OPC-4392 and (-)-3-PPP did not produce this behavior. These findings suggest that OPC-14597 provokes yawning without causing stereotypy and rotation but markedly antagonizes the talipexole-induced yawning and apomorphine-induced stereotypy, and that OPC-14597 thus exerts partial agonistic effects on yawning behavior but antagonistic effects on stereotypy in rats.

[In vitro and in vivo activities of sulopenem compared with those of imipenem and cephalosporins]

The in vitro and in vivo antibacterial activities of sulopenem (CP-70,429),a new parenteral penem antibiotic, were compared with those of imipenem (IPM), flomoxef, cefuzonam (CZON) and cefotaxime. Sulopenem possessed broad-spectrum activities against Gram-positive bacteria and Gram-negative bacteria. Antibacterial activities of sulopenem against methicillin-sensitive Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Streptococcus pyogenes and Streptococcus pneumoniae were equivalent to or somewhat superior to those of IPM. Against members of the family Enterobacteriaceae, sulopenem was 4- to 260-fold more active than reference antibiotics with broad-spectra. In a killing kinetics study for Haemophilus influenzae, sulopenem showed a 99.9% decrease of viable cells after 8 hours at a concentration of 0.20 micrograms/ml. This effect was obtained at a concentration 8-fold lower than that of IPM. The protective effects of sulopenem in murine experimental systemic infections were superior to those of imipenem/cilastatin. In murine experimental mixed infection with Escherichia coli and Bacteroides fragilis, sulopenem had lower ED50, in other words stronger antimicrobial activities than IPM. The therapeutic effect of sulopenem are related well with its MIC value. In guinea pigs experimental lung infection with Klebsiella pneumoniae, sulopenem was more effective than CZON or cefotiam.

Involvement of catecholamine receptor activities in modulating the incidence of yawning in rats

Possible involvement of catecholamine receptor activities in modulating the incidence of yawning, which involves activation of dopaminergic-cholinergic linked neuronal mechanism, was investigated in rats. Subcutaneous injection of talipexole (B-HT 920), a selective dopamine D2-receptor-agonist, elicited yawning behavior. This behavior was increased by prazosin and bunazosin, alpha 1-adrenoceptor antagonists, and by pindolol, a beta-adrenoceptor antagonist. The yawning induced by physostigmine, an anticholinesterase agent, and pilocarpine, a direct muscarinic receptor agonist, was increased by pindolol, but was unaffected by prazosin and bunazosin. In addition, the yawning induced by the dopaminergic agonists, but not by the cholinergic agonists, was markedly suppressed by ST587, an alpha 1-adrenoceptor agonist. All the yawning responses to dopaminergic and cholinergic agents were reduced not only by scopolamine, a muscarinic receptor antagonist, but also by idazoxan, rauwolscine, and yohimbine, alpha 2-adrenoceptor antagonists. The results suggest that catecholamine receptor activities seem to play different roles in inhibitory modulation of the occurrence of yawning caused by dopaminergic and cholinergic stimulation.

Oxygen intake efficiency slope: a new index of cardiorespiratory functional reserve derived from the relationship between oxygen consumption and minute ventilation during incremental exercise

We investigated the usefulness of the oxygen intake efficiency slope (OIES) as a submaximal measure of cardiorespiratory functional reserve. OIES was derived from the relationship between oxygen consumption (VO2; ml/min) and minute ventilation (VE; l/min) during incremental exercise, which was determined by the following equation: VO2 = a logVE + b, where "a" represents OIES, which shows the effectiveness of ventilation. Maximal oxygen consumption (VO2max) is effort-dependent. There is no standard submaximal measurement of cardiorespiratory reserve that provides generally acceptable results. Exercise tests were performed by 17 normal volunteers on an ergometer using a symptom-limited Ramp protocol. Expired gas was continuously analyzed. OIES was calculated using the first 75%, 90%, and 100% of exercise data. We also determined the following submaximal parameters: the ventilatory anaerobic threshold (VAT), the slope of the minute ventilation-carbon dioxide production relationship (VE-VCO2 slope), and the extrapolated maximal oxygen consumption (EMOC). We analyzed the relationship between OIES, other submaximal parameters and VO2max, and examined the effects of submaximal exercise on OIES. The correlation coefficient of the logarithmic curve-fitting model was 0.991 +/- 0.006. OIES and VO2max were significantly correlated (r = 0.966, p < 0.0001). The correlation between OIES and VO2max was stronger than the correlation between VO2max and VAT, the VE-VCO2 slope and EMOC. OIES values for 100% and 90% of exercise were identical; OIES for 75% of exercise was slightly lower (3%). Our results suggested that OIES may provide an objective, effort-independent estimation of cardiorespiratory functional reserve.