Proliferative activity of canine mast cell tumours evaluated by bromodeoxyuridine incorporation and Ki-67 expression

The proliferative activity of 91 canine mast cell tumours was assessed on the basis of the Ki-67 positive index (Ki-67 PI) and mitotic index (MI) and, in 15 cases, also by the labelling index of bromodeoxyuridine (BrdU; an analogue of tritiated thymidine) incorporated in vivo into S-phase cells. BrdU and Ki-67 were detected immunohistochemically. The tumours were graded histologically (I, II or III). The BrdU labelling index (BrdU LI) tended to increase as the grade became higher. In terms of the mean values of Ki-67 PI, significant differences were found between histological tumour grades I and II (P < 0.01) and between grades II and III (P < 0.01). In terms of mean MI, grades I and II were found to differ significantly (P < 0.05). With Spearman rank correlation coefficient and linear regression analysis, the BrdU LI and Ki-67 PI showed a highly significant correlation. This strong correlation indicated that Ki-67 was, like BrdU, a useful marker for proliferative potential in canine mast cell tumours; moreover, its use did not require the prior administration of any reagent to the live animal.

Fatal infection with human pinworm, Enterobius vermicularis, in a captive chimpanzee

A fatal infection with human pinworms, Enterobius vermicularis, was found in a 26-year-old chimpanzee kept in a zoo. Grossly, the animal was highly emaciated, and had severe enteritis with cecal multifocal nodules and severe cholelithiasis. Histopathologically, a large number of human pinworms were observed in the nodular lesions in the cecum and intestinal wall. These migrating worms were surrounded by an inflammatory cell infiltration which lacked eosinophils. There were areas of multifocal hyperemia and/or hemorrhages in various organs including the entire gastrointestinal tract. Pinworms were also observed in the portal venule and parenchyma of the liver. A light infection with Strongyloides cf. stercoralis was also observed.

The critical role of the PE21 element in oncostatin M-mediated transcriptional repression of the p53 tumor suppressor gene in breast cancer cells

Cytokine oncostatin M (OM) exerts growth-inhibitory and differentiative effects on breast cancer cells. Previously we showed that the transcription from the p53 gene in breast cancer cells was down regulated by OM. To elucidate the molecular mechanisms underlying the OM effect on p53 transcription, in this study, we dissected the p53 promoter region and analysed the p53 promoter activity in breast tumor cells. We showed that treatment of MCF-7 cells with OM induced a dose- and time-dependent suppression of p53 promoter activity. The p53 promoter activity was decreased to 35% of control at 24 h and further decreased to 20% at 48 h by OM at concentrations of 5 ng/ml and higher. Deletion of the 5'-flanking region of the p53 promoter from -426 to -97 did not affect the OM effect. However, further deletion to -40 completely abolished the repressive effect of OM. The p53 promoter region -96 to -41 contains NF-kappaB and c-myc binding sites, and a newly identified UV-inducible element PE21. Mutations to disrupt NF-kappaB binding or c-myc binding to the p53 promoter decreased the basal promoter activity without affecting the OM-mediated suppression, whereas mutation at the PE21 motif totally abolished the OM effect. We further demonstrated that insertion of PE21 element upstream of the thymidine kinase minimal promoter generated an OM response analogous to that of the p53 promoter. Finally, we detected the specific binding of a nuclear protein with a molecular mass of 87 kDa to the PE21 motif. Taken together, we demonstrate that OM inhibits the transcription of the p53 gene through the PE21 element. Thus, the PE21 element is functionally involved in p53 transcription regulated by UV-induction and OM suppression.

FK506 attenuates early ischemic neuronal death in a monkey model of stroke

FK506 is an immunosuppressive agent that has been reported to have neuroprotective effects in several kinds of rodent models of stroke. The purpose of this study was to evaluate the neuroprotective effects of FK506 in a monkey model of stroke.

METHODS

Cynomolgus monkeys underwent 3 h of occlusion followed by 5 h of reperfusion of the right middle cerebral artery (MCA) through a transorbital approach. A single bolus dose of FK506 (0.1 mg/kg) was injected intravenously 5 or 175 min after MCA occlusion. Eight hours after ischemia, a neuropathologic study was performed and the volume of ischemic damage was determined. To measure local cerebral blood flow (CBF), the cerebral metabolic rate of oxygen (CMRO(2)), and the oxygen extraction fraction during the experiments, PET scans were obtained using a steady-state (15)O continuous-inhalation method. Four consecutive PET scans (before and 2 h after ischemia and immediately and 3 h after reperfusion) were obtained on each monkey.

RESULTS

Treatment with FK506 (0.1 mg/kg) 5 or 175 min after ischemia significantly reduced cortical damage 8 h after ischemia by 82% (P < 0.05) and 73% (P < 0.05), respectively. In PET studies, FK506 did not affect CBF or physiologic parameters in any treatments. In the FK506-treated group, a volume of >40% CMRO(2) reduction 3 h after reperfusion decreased significantly (P < 0.05).

CONCLUSION

This study showed that FK506 showed a powerful neuroprotective effect in a nonhuman primate model of stroke. The therapeutic time window of FK506 was at least 3 h after onset. PET studies detected neuroprotective effects only in areas with >40% CMRO(2) reduction 3 h after reperfusion.

Adrenomedullin reduces ischemic brain injury after transient middle cerebral artery occlusion in rats

BACKGROUND

The effect of adrenomedullin, a vasodilatory peptide on transient middle cerebral artery (MCA) occlusion was investigated in rats.

METHODS

Transient MCA occlusion for 2 hours was made by using the intra-arterial suture method, followed by reperfusion.

FINDINGS

An intravenous infusion of adrenomedullin (1 microg/kg/min) from one hour before ischemia to one hour after ischemia significantly reduced the infarct size and improved neurological deficits (p<0.05), without affecting systemic blood pressure or other physiological parameters. The infarct size was reduced with adrenomedullin by 25.4+/-12.7%, 31.3+/-5.8%, 31.6+/-6.1% respectively at the coronal level 6, 8 and 10 mm posterior from the frontal pole. Adrenomedullin also significantly inhibited the increase in myeloperoxidase (MPO) activity in the MCA area of the ischemic hemisphere after 22-hour reperfusion (control: 0.205+/-0.054 unit/g wet tissue, adrenomedullin group: 0.047+/-0.009 unit/g wet tissue, p<0.0001).

INTERPRETATION

These data suggest that adrenomedullin reduces acute ischemic brain injury and one of is neuroprotective mechanisms may be derived from inhibition of the infiltration of neutrophils into the ischemic tissue.

Lingual calcinosis circumscripta in a captive sitatunga

Calcinosis circumscripta (CC) was found in a 10-yr-old female sitatunga (Bovidae; Tragelaphus spekei). At necropsy, there were two white coalescing nodules (3 x 5 x 2 cm, 2 x 2 x 1.5 cm) on the ventral side of the tongue. The cut surface of the nodules had multiple, well-circumscribed loculi with chalky appearance and gritty consistency, separated by thin strands of connective tissue. Histologically, the nodules contained multiple loculi of various sizes and shapes, which consisted of amorphous material that was pale basophilic with H&E stain, surrounded by fibrous connective tissue. Around the loculi were numerous foreign body giant cells and epithelioid macrophages; occasional lymphocyte aggregations also were seen. The amorphous material was positive for PAS and von Kossa's stain. Calcinosis circumscripta is rare in the Bovidae.

Reduced myocardial sarcoplasmic reticulum Ca(2+)-ATPase mRNA expression and biphasic force-frequency relations in patients with hypertrophic cardiomyopathy

BACKGROUND

The relationship between left ventricular (LV) contractile functional reserve and gene expression of Ca(2+)-handling proteins in patients with hypertrophic cardiomyopathy (HCM) remains to be clarified.

METHODS AND RESULTS

We calculated the maximum first derivative of LV pressure (LV dP/dt(max)) and the LV pressure half-time (T(1/2)) during pacing in 14 patients with nonobstructive HCM (LV ejection fraction >55%) and 7 control subjects. Endomyocardial tissue was obtained, and mRNA levels of sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2), ryanodine receptor-2, phospholamban, calsequestrin, and Na(+)/Ca(2+) exchanger were quantified by use of a real-time quantitative reverse transcription-polymerase chain reaction method. Group A consisted of 7 HCM patients who showed a progressive rise in the LV dP/dt(max) with increased heart rate. Group B consisted of 7 HCM patients in whom the heart rate-LV dP/dt(max) relation was biphasic at physiological pacing rates. Both the mean maximal wall thickness and the LV hypertrophy score in group B were greater than in group A (20+/-5 versus 15+/-3 mm and 7+/-1 versus 5+/-2 points, respectively). SERCA2 mRNA levels were significantly lower in group B (SERCA2/GAPDH ratio 0.34+/-0.15) compared with group A (0.72+/-0.27) and control subjects (0.85+/-0.47), whereas the mRNA expression of ryanodine receptor-2, phospholamban, calsequestrin, and Na(+)/Ca(2+) exchanger were similar in all groups.

CONCLUSIONS

These results suggest that downregulation of SERCA2 mRNA, resulting in altered Ca(2+) handling, may contribute to impaired LV contractile reserve in HCM patients with severe hypertrophy, even in the absence of detectable baseline systolic dysfunction.

Side-chain metabolism of propranolol: involvement of monoamine oxidase and aldehyde reductase in the metabolism of N-desisopropylpropranolol to propranolol glycol in rat liver

The further metabolism of N-desisopropylpropranolol (NDP), a side-chain metabolite of propranolol (PL), was investigated in isolated rat hepatocytes. Propranolol glycol (PGL) was generated from NDP as a major metabolite. Naphtetrazole (NTE), a potent inhibitor of monoamine oxidase (MAO), significantly retarded the disappearance of NDP from the incubation medium, suggesting the involvement of MAO in the deamination of NDP to an aldehyde intermediate. In a reaction mixture of rat liver mitochondria and cytosol with NADPH, phenobarbital, a specific inhibitor of aldehyde reductase, and 4-nitrobenzaldehyde (4-NBA), a substrate inhibitor of aldehyde reductase, decreased the formation of PGL from NDP. 4-NBA was a competitive inhibitor of the enzyme responsible for the PGL formation. The optimal pH for the formation of PGL from NDP in the reaction mixture was approximately 8.0. Based on these results, we propose the possibility that, in the rat liver, MAO catalyzes the oxidative deamination of NDP to an aldehyde intermediate and the formed aldehyde intermediate is subsequently reduced to PGL by aldehyde reductase. Furthermore, the enantioselective metabolism of NDP to PGL was examined. In isolated rat hepatocytes, the amount of PGL formed from S-NDP [S(-)-form of NDP] was larger than that of PGL formed from R-NDP [R(+)-form of NDP].

Biphasic changes in left ventricular end-diastolic pressure during dynamic exercise in patients with nonobstructive hypertrophic cardiomyopathy

OBJECTIVES

The aim of this study was to clarify the serial changes in left ventricular (LV) end-diastolic pressure (LVEDP) during dynamic exercise in patients with hypertrophic cardiomyopathy (HCM).

BACKGROUND

Although HCM is characterized by impaired resting LV diastolic function, serial changes in LVEDP during exercise have not been characterized.

METHODS

We simultaneously measured LV pressure and LV dimensions during symptom-limited supine bicycle exercise in 5 healthy individuals and 20 patients with HCM. Exercise thallium-201 scintigraphic studies were also performed.

RESULTS

The LVEDP (baseline: 12 +/- 5 mm Hg) progressively increased to a maximum value at peak exercise (28 +/- 8 mm Hg) in 11 patients with HCM (group I). In the remaining nine patients with HCM (group II), changes in LVEDP during exercise were biphasic, with an initial progressive increase and a subsequent gradual decline up to peak exercise (14 +/- 4 mm Hg at baseline, 27 +/- 5 mm Hg at the critical heart rate, 16 +/- 3 mm Hg at peak exercise). Exercise-induced changes in LV dimensions and LV peak systolic pressures were similar in both groups. However, the maximum first derivative of LV pressure was greater and the LV pressure half-time was shorter in group II than in group I at a similar peak exercise heart rate. The biphasic changes in LVEDP disappeared by pretreatment with propranolol. The LV hypertrophy scores were higher in group I than in group II. Exercise thallium-201 images showed more severe perfusion defects in group I than in group II patients.

CONCLUSIONS

The biphasic changes in LVEDP seen during exercise may be related to improved coronary microcirculation in response to beta-adrenergic stimulation in patients with mild to moderate HCM.

Elevation of nitric oxide metabolites in the cerebrospinal fluid of patients with moyamoya disease

BACKGROUND

To investigate whether nitric oxide (NO) contributes to formation of abnormal collateral circulation in patients with moyamoya disease.

METHODS

Cerebrospinal fluid (CSF) samples were obtained from the subarachnoid space of the Sylvian fissure during combined bypass surgery for moyamoya disease and kept frozen until NO metabolites, nitrate and nitrite, were measured using a Griess method.

RESULTS

Compared with control CSF obtained from 18 patients with hemifacial spasm, unruptured aneurysm, etc., concentrations of NO metabolites in 26 CSF samples of 18 patients with moyamoya disease were significantly higher (mean +/- SE; 17.6 +/- 1.2 vs. 10.5 +/- 1.0 microM, p < 0.01). In eight patients, the CSF samples from both the first and second operation could be obtained. NO metabolite concentrations (20.5 +/- 2.3 microM) in CSF obtained from the first surgery decreased to 15.7 +/- 1.8 microM (p < 0.01) in CSF obtained from the second, contralateral procedure. The cases of moyamoya disease with greater development of moyamoya vessels at angiographic stage 3 and 4 tended to show higher concentrations of NO metabolites than cases at earlier or later stages with a few moyamoya vessels.

INTERPRETATION

Nitric oxide concentrations in CSF are chronically elevated in moyamoya disease, probably reflecting development of abnormal collateral circulation. i.e. moyamoya vessels. Vascular bypass surgery can reduce abnormal collateral circulation with reduced production of nitric oxide.

Phencyclidine impairs latent learning in mice: interaction between glutamatergic systems and sigma(1) receptors

The effect of phencyclidine (PCP) on latent learning was investigated using a one-trial water-finding task in mice. Mice without water deprivation were given PCP or saline before a training trial, which consisted of exposure to a novel open-field environment with an alcove containing a water tube. Twenty to twenty-four hours after water deprivation, animals were placed in the same apparatus and the time required to find the water tube measured (test trial). Saline-treated trained mice showed a significantly shorter time to find the water tube during the test trial (finding latency) than naive mice that had not been trained. When PCP (1mg/kg i.p.) was administered before the training trial, the finding latency was significantly prolonged in comparison with that in the saline-treated mice, indicating that PCP induced impairment of latent learning. 1-(3,4-Dimethoxy-phenethyl)-4-(3-phenylpropyl)piperazine dihydrochloride (SA4503: 0.3 mg/kg s.c.) and (+)-pentazocine (1 mg/kg s.c.), selective sigma(1) receptor agonists, or D-cycloserine (10 and 30mg/kg, s.c.), a glycine binding site agonist, significantly counteracted the PCP-induced impairment of latent learning, whereas (+)-SKF-10,047 (0.1-3 mg/kg s.c.), a putative sigma(1) receptor agonist, did not. The ameliorating effects of SA4503 and (+)-pentazocine were antagonized by N,N-dipropyl-2-(4-methoxy-3-(2-phenylethoxy) phenyl) ethylamine (NE-100: 1 mg/kg i.p.), a selective sigma(1) receptor antagonist. SA4503 also ameliorated the impairment of latent learning induced by dizocilpine, a non-competitive N-methyl-D-aspartate receptor antagonist, the effect being antagonized by NE-100. These results suggest that PCP induces an impairment of latent learning, this effect being mediated via glutamatergic systems, and that activation of sigma(1) receptors ameliorates impairment of latent learning induced by PCP.

X-rays induce dose-dependent and cell cycle-independent accumulation of p21(sdi1/WAF1)

Cell cycle arrest at the G1 checkpoint is governed by a function of wild-type p53. We assessed the behavior of the sdi1 gene, which codes for a 21kDa potent inhibitor of cdk/cyclins, after X-irradiation. X-irradiation induced sdi1 mRNA accumulation and G1 arrest only in cells possessing wild-type p53. Elevation of p21(sdi1/WAF1) was preceded by p53 accumulation, which occurred despite p53 mRNA constancy in normal cells growing in the log phase. The quantity of accumulated p53 and p21(sdi1/WAF1) was radiation dose dependent. A decrease in the S phase cell population in normal cells observed after irradiation reached a minimum at less-than-maximum levels of p53 and p21(sdi1/WAF1). Furthermore, an accumulation of p53 and p21(sdi1/WAF1) was also observed when cells were synchronized in the G0, G1 and S phase and X-irradiated. These results indicated that an X-ray induced p53 and p21(sdi1/WAF1) accumulation mechanism exists throughout the cell cycle, and that the signal strength induced by X-irradiation is dose-dependent.

Enantioselective metabolism of propanolol in isolated hepatocytes prepared from untreated, PB- or 3-MC-pretreated rats

The present paper describes the metabolism of a chiral drug propranolol (PL) using isolated hepatocytes freshly prepared from untreated, PB- or 3-MC-pretreated rats. In order to examine not only the existence of enantioselectivity but also the effect of enzyme inducer (PB or 3-MC) on PL metabolism, 500 microM PL (RS-PL, R(+)-PL or S(-)-PL) was incubated at 37 degrees C using 8 x 10(6) cells/ml isolated rat hepatocytes. Then, the elimination amount of PL and the formation amounts of eight kinds of the metabolites including ring hydroxylated metabolites (4-OH-, 5-OH- and 7-OH-PL) and side chain metabolites (NDP, AcNDP, PGL, NLA and NAA) were simultaneously determined by HPLC. By 3-MC- and PB-pretreatment, a significant increase was noticed in PL elimination and also in the formation of PL metabolites, NDP, NLA and NAA. Furthermore, the presence of enantioselectivity was observed, i.e. the substrate R(+)-PL was always eliminated faster than the substrate S(-)-PL. Regarding the metabolite formation, NDP, AcNDP and NAA were dominantly produced from R(+)-PL, and NLA, PGL and the ring hydroxylated metabolites from S(-)-PL. In all cases of PL elimination and the metabolite formation, the amounts of the metabolites derived from RS-PL indicated the mean values of the respective amounts derived from R(+)-PL and S (-)-PL. Using the three kinds of isolated rat hepatocytes mentioned above, the kinetic parameters of NDP-formation at 37 degrees C for 10 min were calculated using RS-PL, R(+)-PL or S(-)-PL as a substrate. From the pseudo values of V'max/K'm (microliter/min.8 x 10(6) cells), the easiest formation of NDP from R(+)-PL was observed in the rat hepatocyte system pretreated with 3-MC.

Hypervascular liver metastasis from hypovascular ductal cell carcinoma of the pancreas

In a case of hypervascular metastatic liver tumor, the vascularity of primary focus, pancreatic carcinoma was hypovascular. Based on the imaging findings, we thought before the operation that the two lesions were double cancers. Histological examination showed that the stromal volume of metastatic tumorous tissue was richer than that of the primary focus. It was suggested that the difference in the stromal volume was related to the difference of the vascularity. Some foctors originating in stromal cells might be involved in angiogenesis.

An actigraphic comparison of sleep restriction and sleep hygiene treatments for insomnia in older adults

We compared the efficacy of sleep restriction therapy combined with sleep hygiene, nap modification of sleep restriction therapy combined with sleep hygiene, and sleep hygiene alone as treatments for insomnia in 39 community-dwelling men and women 55 years and older. We used the wrist actigraph as an objective outcome measure for all subjects at baseline, end of treatment, and 3-month follow-up; polysomnography (PSG) was conducted in a subgroup of subjects. Although subjects appeared to follow restriction instructions through follow-up, we found few between-group differences in treatment efficacy. Lack of treatment effect might be explained by the efficacy of HYG as a treatment in itself and the relatively low symptom level in these healthy older poor sleepers. At baseline, actigraphic results were found to correlate more highly than sleep log data with PSG in our sample. Actigraphic total sleep time, in particular, was highly correlated with PSG.

Identification and characterization of corpuscular, soluble and secreted antigens of a Venezuelan isolate of Anaplasma marginale

Anaplasma marginale is the etiological agent of anaplasmosis, a tick-transmitted disease with an important economic impact that affects cattle throughout the world. Although, North American isolates of A. marginale and their antigens have been extensively studied, relatively little information is available on the antigenic composition of South American isolates. The characterization of diverse geographical isolates of A. marginale will result in a thorough antigenic profile and may lead to the identification of additional diagnostic and immunoprophylactic tools. Short-term cultures of a Venezuelan isolate (Ta) of A. marginale were maintained for up to 13 days in vitro. During that period, the A. marginale remained viable and were propagated in the bovine erythrocyte culture system. During the initial days of culture, cell division and reinvasion were evidenced by a significant rise in parasitemia up to a 50%. A. marginale antigens were identified by metabolic labeling with (35S) methionine, followed by fractionation and immunoprecipitation with homologous and heterologous bovine sera. This yielded a complete antigenic set for the Ta isolate of A. marginale, including soluble, secreted and corpuscular polypeptide antigens. Fifteen immunodominant polypeptides were recognized by the bovine sera in the soluble and corpuscular fractions with relative molecular weights of 200, 150, 100-110, 86, 60, 50, 47, 40, 37, 33, 31, 25, 23, 19 and 16kDa. Seven polypeptides were present in the exoantigen fraction. The 31 and 19kDa antigens were recognized by the ANAR76A1 and ANAF16C1 monoclonal antibodies, respectively which are specific for MSP-4 and MSP-5 from North American isolates of A. marginale. Metabolic labeling with (14C) glucosamine prior to immunoprecipitation with bovine sera allowed the identification of glycoprotein antigens of 200, 100-150, 60, 55, 50, 45-43, 37, 33, 31, 22, 19 and 16kDa in the soluble fraction.

Three-dimensional stereotactic surface projection analysis of macaque brain PET: development and initial applications

To characterize better the local brain functions of conscious rhesus macaques, we developed automated image analysis techniques for monkey PET images, examined the cerebral glucose metabolism of monkeys, and compared it with that of humans.

METHODS

Glucose metabolic PET images from 11 monkeys were obtained using a high-resolution animal PET scanner after intravenous administration of FDG. T1-weighted MR images were obtained from 6 of the monkeys. Referencing a bicommissural stereotactic macaque brain atlas, we created a PET brain template using coregistered MR images. Each individual PET image set was transformed to the PET template through an automated affine transformation, followed by nonlinear warping along the directions of the major neuronal fiber bundles in the brain. For minimization of residual anatomic variability, metabolic activities were extracted using 3-dimensional stereotactic surface projections. The effects of anatomic standardization were evaluated using MR images. Patterns of cerebral glucose metabolism of young versus aged monkeys were examined. The metabolic activities of aged monkeys were compared with those of elderly healthy human volunteers that had been analyzed similarly.

RESULTS

Anatomic standardization reduced individuals' anatomic variability as evidenced by a reduction in the number of MR pixels with higher SDs calculated across monkeys. Coefficient-of-variation maps of conscious monkeys revealed that the greatest metabolic variances were near the central sulci and occipital cortices. Age-associated glucose metabolic reductions were most pronounced in the occipital lobe, caudate nucleus, and temporal lobe. Compared with human brains, the monkey frontal lobe and posterior cingulate gyrus had significantly less metabolic activity and the supramarginal gyrus and vermis had significantly more metabolic activity.

CONCLUSION

The proposed method permits pixel-by-pixel characterization of the metabolic activities of rhesus macaque brains in the stereotactic coordinate system. Greater metabolic variances in the central sulcus region and occipital lobe suggest potential difficulties in controlling sensory input and motor output or planning in conscious monkey experiments. The analyses revealed age-related metabolic reductions in monkeys and marked differences in metabolic patterns between aged monkey brains and aged human brains. The proposed brain-mapping technique enables reproducible and observer-independent analyses and will serve as an important investigative tool for primate brain imaging research.

Cavitary pulmonary metastases of gallbladder cancer

We report a case of multiple cavitary pulmonary metastases of gallbladder cancer. Radiologically, every cavity displayed a very thin wall containing only air inside. The postmortem histopathological examination showed that: (1) the cavities were surrounded by normal alveoli; (2) these walls were composed mostly of adenocarcinoma cells; (3) necrotic or mucous substance was sparse in the cavity space; (4) cancer cells infiltrated along the surface of the alveolar septa, and (5) the morphology of the cancer cells of the gallbladder and the lung was the same. It seemed likely that the thin-walled cavities in the lung might result from central breakdown of the tumor and subsequent expectoration of debris through the connected airways.

Effects of sigma receptor agonists on the impairment of spontaneous alternation behavior and decrease of cyclic GMP level induced by nitric oxide synthase inhibitors in mice

In this study, we investigated the involvement of the interaction between sigma receptors and the nitric oxide/cyclic GMP pathway in short term memory in mice, assessed through spontaneous alternation behavior in a Y-maze. N(G)-Nitro-L-arginine methyl ester and 7-nitro indazole, both nitric oxide synthase inhibitors, impaired the spontaneous alternation behavior. These impairments were attenuated by (+) SKF 10,047 and (+) pentazocine, sigma(1) receptor agonists. Further, the sigma(1) receptor antagonist, NE-100, reversed the improvements made by sigma receptor agonists. Cyclic GMP levels and nitric oxide synthase activity in the hippocampus were reduced by treatment with N(G)-nitro-L-arginine methyl ester. The suppressive effects of N(G)-nitro-L-arginine methyl ester on the cyclic GMP levels were reversed by co-treatment with (+) SKF 10,047, but the decline in nitric oxide synthase activity was not. These results suggest that the nitric oxide/cyclic GMP pathway in the hippocampus is responsible for spontaneous alternation behavior in a Y-maze. Further, the ameliorating effects of (+) SKF 10,047 on the impairment of spontaneous alternation behavior may be mediated through activation of guanylate cyclase, but not nitric oxide synthase in the hippocampus of mice.

Different beta-adrenergic regulation of myocardial contraction and relaxation between apical and nonobstructive hypertrophic cardiomyopathy

BACKGROUND

The impaired adrenergic control of both inotropic and lusitropic reserves has been evaluated in patients with hypertrophic cardiomyopathy (HCM) but not in those with apical HCM (APH).

OBJECTIVES

We examined the influence of increases in heart rate and adrenergic stimulation on inotropic and lusitropic reserves in HCM and APH with normal resting left ventricular (LV) systolic function.

METHODS

We evaluated LV isovolumic contraction and relaxation during atrial pacing and during supine leg exercise in 7 patients with APH and in 8 patients with HCM.

RESULTS

Heart rate was significantly correlated with LV isovolumic contraction and relaxation during pacing and exercise in all patients. In all patients with APH, the increase in LV isovolumic contraction was greater during exercise (101%) than pacing alone (27%) for similar increase in heart rate. In 5 patients with HCM, the increase in LV isovolumic contraction was greater during exercise (83%) than pacing alone (24%), whereas in 3 patients with HCM the increase in LV isovolumic contraction was similar between during exercise (25%) and during pacing alone (22%). In all patients with APH, relaxation was shorter during exercise (39%) than pacing alone (16%). Conversely, in patients with HCM relaxation was similarly shortened between during pacing alone (20%) and during exercise (19%).

CONCLUSIONS

The force-frequency and the relaxation-frequency relations were well-preserved in all patients. In patients with HCM, the adrenergic enhancement of force-frequency relation and/or relaxation-frequency relation was impaired. In patients with APH, however, adrenergic control of both force-frequency and relaxation-frequency relations was well-preserved, which may indicate a preserved beta-adrenergic signaling pathway.