The p38α mitogen-activated protein kinase is a key regulator of myelination and remyelination in the CNS.

The p38α mitogen-activated protein kinase (MAPK) is one of the serine/threonine kinases regulating a variety of biological processes, including cell-type specification, differentiation and migration. Previous in vitro studies using pharmacological inhibitors suggested that p38 MAPK is essential for oligodendrocyte (OL) differentiation and myelination. To investigate the specific roles of p38α MAPK in OL development and myelination in vivo, we generated p38α conditional knockout (CKO) mice under the PLP and nerve/glial antigen 2 (NG2) gene promoters, as these genes are specifically expressed in OL progenitor cells (OPCs). Our data revealed that myelin synthesis was completely inhibited in OLs differentiated from primary OPC cultures derived from the NG2 Cre-p38α CKO mouse brains. Although an in vivo myelination defect was not obvious after gross examination of these mice, electron microscopic analysis showed that the ultrastructure of myelin bundles was severely impaired. Moreover, the onset of myelination in the corpus callosum was delayed in the knockout mice compared with p38α fl/fl control mice. A delay in OL differentiation in the central nervous system was observed with concomitant downregulation in the expression of OPC- and OL-specific genes such as Olig1 and Zfp488 during early postnatal development. OPC proliferation was not affected during this time. These data indicate that p38α is a positive regulator of OL differentiation and myelination. Unexpectedly, we observed an opposite effect of p38α on remyelination in the cuprizone-induced demyelination model. The p38α CKO mice exhibited better remyelination capability compared with p38α fl/fl mice following demyelination. The opposing roles of p38α in myelination and remyelination could be due to a strong anti-inflammatory effect of p38α or a dual reciprocal regulatory action of p38α on myelin formation during development and on remyelination after demyelination.

Peptidoglycan inhibits progesterone and androstenedione production in bovine ovarian theca cells.

Uterine bacterial infection perturbs uterine and ovarian functions in postpartum dairy cows. Peptidoglycan (PGN) produced by gram-positive bacteria has been shown to disrupt the ovarian function in ewes. The aim of this study was to determine the effect of PGN on steroid production in bovine theca cells at different stages of follicular development. Bovine theca cells isolated from pre- and post-selection ovarian follicles (<8.5mm and >8.5mm in diameter, respectively) were cultured in vitro and challenged with PGN. Steroid production was evaluated by measuring progesterone (P4) and androstenedione (A4) concentration in culture media after 48 h or 96 h of culture. Bovine theca cells expressed PGN receptors including Toll-like receptor 2 and nucleotide-binding oligomerization domain 1 and 2. Treatment with PGN (1, 10, or 50 µg/ml) led to a decrease in P4 and A4 production by theca cells in both pre- and post-selection follicles. The mRNA expression of steroidogenic enzymes were decreased by PGN treatment. Moreover, A4 production was further suppressed when theca cells of post-selection follicles were simultaneously treated by PGN and lipopolysaccharide (0.1, 1, or 10 µg/ml). These findings indicate that bacterial toxins may act locally on ovarian steroidogenic cells and compromise follicular development in postpartum dairy cows.

Relationship between aerobic endurance training and dynamic cerebral blood flow regulation in humans.

The incidence of orthostatic intolerance is elevated in endurance-trained individuals. We sought to test the hypothesis that aerobic endurance training is associated with an attenuated control of the cerebral vasculature. Endurance trained (ET, n = 13) and age-matched untrained (UT, n = 11) individuals (peak O2 consumption, mean ± SEM; 63 ± 1 vs 42 ± 1 mL/min/kg, P < 0.05) were examined while supine and seated upright. Dynamic cerebral autoregulation (CA) was assessed by calculation of the rate of regulation (RoR) from the arterial blood pressure (ABP) and middle cerebral artery (MCA) mean blood velocity (V mean ) responses to a bilateral thigh cuff release, which evoked a transient hypotension. Cerebral oxygenation (oxyhemoglobin; HbO2 ) was determined with near-infrared spectroscopy. When seated upright, cuff release evoked a greater decrease in ABP (P < 0.001), MCA V mean (P = 0.096) and HbO2 (P < 0.001) in ET compared with UT. However, RoR was similar in ET and UT individuals while seated upright (to 0.193 ± 0.039 vs 0.129 ± 0.029/s, P > 0.05), and there was no significant difference in the relative change in RoR from the supine to upright positions (ΔRoR: -65 ± 7 and -69 ± 7%, for ET and UT, respectively). These findings suggest that aerobic endurance training is not associated with an attenuation in dynamic CA.

Predominant involvement of the cerebellum in guinea pigs infected with bovine spongiform encephalopathy (BSE).

This study reports the experimental transmission of bovine spongiform encephalopathy (BSE) to guinea pigs and describes the cerebellar lesions in these animals. Guinea pigs were inoculated intracerebrally with 10% brain homogenates from BSE-affected cattle. These animals were designated as the first passage. Second and third passages were subsequently performed. All guinea pigs developed infection at each passage. The mean incubation period of the first passage was 370 days post-infection (dpi) and this decreased to 307 dpi and 309 dpi for the second and third passages, respectively. Mild to severe spongiform degeneration and gliosis were observed in the cerebral cortex, thalamus and brainstem. In addition, the affected animals had marked pathological changes in the cerebellum characterized by severe cortical atrophy associated with Bergmann radial gliosis of the molecular layer and reduction in the width of the granular cell layer. Immunohistochemically, intense PrP(Sc) deposition and scattered plaque-like deposits were observed in the molecular and granular cell layers. Cerebellar lesions associated with severe atrophy of the cortex have not been reported in animal prion diseases, including in the experimental transmission of PrP(Sc) to small rodents. These lesions were similar to the lesions of human kuru or the VV2 variant of sporadic Creutzfeldt-Jakob disease, although typical kuru plaques or florid plaques were not observed in the affected animals.

CSF angiotensin II and angiotensin-converting enzyme levels in anti-aquaporin-4 autoimmunity.

BACKGROUND: Anti-aquaporin-4 (AQP4) antibody targets perivascular astrocyte foot processes, which contain abundant angiotensinogen, a precursor of angiotensin II, angiotensin-converting enzyme (ACE) and ACE2. OBJECTIVE: To disclose any abnormality in the intrathecal angiotensin II metabolic pathway in Japanese patients with neuromyelitis optica (NMO) or NMO spectrum disorders (NMOs) and positive for anti-AQP4 antibody. METHODS: We measured CSF angiotensin II, ACE and ACE2 levels in 15 anti-AQP4 antibody-positive patients with NMO or NMOs, 21 anti-AQP4 antibody-negative multiple sclerosis (MS) patients, 32 patients with other neurological diseases (OND) and 24 non-neurologic controls, using established ELISAs. RESULTS: CSF angiotensin II levels were lower in patients with NMO/NMOs (2.01+/-1.82 pg/ml) and those with MS (3.15+/-1.67 pg/ml) than in the OND (5.41+/-2.34 pg/ml) and control groups (6.71+/-2.65 pg/ml) (P(corr)<0.005). The difference in CSF angiotensin II levels between NMO/NMOs and MS patients was nearly significant (P(uncorr)=0.052). In NMO/NMOs and MS patients, angiotensin II levels were negatively correlated with CSF/serum albumin ratio (P<0.05). ACE levels in CSF were lower in patients with NMO/NMOs (34.3+/-5.61 ng/ml) than in MS patients (42.5+/-8.19 ng/ml, P(corr)=0.035) and controls (44.7+/-4.02 ng/ml, P(corr)<0.0003) while ACE2 levels were lower in NMO/NMOs (1.13+/-0.49 ng/ml) and MS (1.75+/-0.86 ng/ml) patients than in controls (2.76+/-0.23 ng/ml, P(corr)<0.001 for both). CONCLUSION: CSF angiotensin II, ACE, and ACE2 levels are decreased in NMO/NMOs patients with anti-AQP4 antibody, reflecting severe destruction of perivascular astrocytes.

Vasodilator therapy with hydralazine induces angiotensin AT receptor-mediated cardiomyocyte growth in mice lacking guanylyl cyclase-A.

BACKGROUND AND PURPOSE: Recent clinical guidelines advocate the use of the isosorbide dinitrate/hydralazine combination in treatment for heart failure. However, clinical and laboratory evidence suggest that some vasodilators may induce cardiac hypertrophy under uncertain conditions. This study investigated the effects and underlying mechanism of action of the vasodilator hydralazine on cardiac growth. EXPERIMENTAL APPROACH: Wild-type mice and animals deficient in guanylyl cyclase-A (GCA) and/or angiotensin receptors (AT(1) and AT(2) subtypes) were treated with hydralazine ( approximately 24 mg.kg(-1).day(-1) in drinking water) for 5 weeks. Cardiac mass and/or cardiomyocyte cross-sectional area, fibrosis (van Giessen-staining) and cardiac gene expression (real-time RT-PCR) were measured. KEY RESULTS: Hydralazine lowered blood pressure in mice of all genotypes. However, this treatment increased the heart and left ventricular to body weight ratios, as well as cardiomyocyte cross-sectional area, and cardiac expression of atrial natriuretic peptide mRNA in mice lacking GCA. Hydralazine did not affect cardiac hypertrophy in wild-type mice and mice lacking either AT(1) or AT(2) receptors alone. However, the pro-hypertrophic effect of hydralazine was prevented in mice lacking both GCA and AT(2), but not GCA and AT(1) receptors. However, hydralazine did decrease cardiac collagen deposition and collagen I mRNA (signs of cardiac fibrosis) in mice that were deficient in GCA, or both GCA and AT(2) receptors. CONCLUSIONS AND IMPLICATIONS: The vasodilator hydralazine induced AT(2) receptor-mediated cardiomyocyte growth under conditions of GCA deficiency. However, attenuation of cardiac fibrosis by hydralazine could be beneficial in the management of cardiac diseases.

Transient acid-impairment of growth ability of oral Streptococcus, Actinomyces, and Lactobacillus: a possible ecological determinant in dental plaque.

INTRODUCTION: Dental plaque pH decreases to about 4 through bacterial fermentation of carbohydrates and this low pH is maintained for from several minutes to about an hour. Repeated acidification causes demineralization of the tooth surface, resulting in caries formation. The acidification also influences plaque bacteria. Severe acidification kills bacteria efficiently, while physiological acidification, the condition occurring in plaque, kills bacteria partially and may impair growth ability. We, therefore, investigated the effects of physiological acidification on representative caries-related bacteria. METHODS: Streptococcus mutans, Streptococcus sobrinus, Streptococcus sanguinis, Streptococcus oralis, Lactobacillus paracasei, and Actinomyces naeslundii were used. Effects of physiological acidification at pH 4.0 on cell viability and growth ability, as well as the growth rate of these bacteria at pH 4.0-7.0, were investigated. RESULTS: Mutans streptococci and Lactobacillus grew at pH 4.0 but the growth of S. sanguinis and S. oralis ceased below pH 4.2 and pH 4.2-4.4, respectively. Acidification at pH 4.0 for 1 h killed 43-89%, 45% and 35-76% of S. sanguinis, S. oralis, and Actinomyces, respectively. Furthermore, assessment of bacterial growth curves revealed that the growth ability of the surviving cells of S. sanguinis, S. oralis and Actinomyces was impaired, but it was recovered within 2-5 h after the environmental pH had returned to 7.0. The acidification neither killed nor impaired the growth of mutans streptococci and Lactobacillus. CONCLUSIONS: These results indicate that physiological and transient acidification is not sufficient to kill bacteria, but it causes a temporary acid-impairment of their growth ability, which may function as an ecological determinant for microbial composition in dental plaque.

Angiotensin-converting enzyme (ACE) and ACE2 levels in the cerebrospinal fluid of patients with multiple sclerosis.

BACKGROUND: We reported a reduction in the levels of angiotensin II in cerebrospinal fluid (CSF) from patients with multiple sclerosis (MS). OBJECTIVE AND METHODS: To clarify the mechanism underlying this reduction, we assayed angiotensin-converting enzyme (ACE) and ACE2 concentrations along with angiotensin II concentrations in CSF samples from 20 patients with MS and 17 controls with non-neurological diseases. RESULTS: ACE levels were significantly elevated in patients with MS compared with controls (48.42 +/- 4.84 vs 44.71 +/- 3.9 pg/mL), whereas ACE2 levels were significantly reduced (2.56 +/- 0.26 vs 2.78 +/- 0.24 pg/mL), acting toward a normalization of angiotensin II levels. CONCLUSION: These results further indicate an alteration of the intrathecal renin-angiotensin system in patients with MS.

Reduced angiotensin II levels in the cerebrospinal fluid of patients with amyotrophic lateral sclerosis.

BACKGROUND: Recent studies suggest that angiotensin II, a major substrate in the renin-angiotensin system, protects neurons through stimulation of its type 2 receptors. However, quite a few clinical studies of angiotensin II levels have shown their relation to disease severity in neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS). AIMS OF THE STUDY: To clarify the significance of angiotensin II in ALS. METHODS: We assayed angiotensin II concentrations in cerebrospinal fluid (CSF) samples from 23 patients with ALS, nine patients with spinocerebellar degeneration (SCD) and 24 control individuals. We evaluated the disability levels of patients with ALS using the Revised ALS Functional Rating Scale (ALSFRS-R) and calculated the disease progression rate (DPR). RESULTS: CSF angiotensin II levels were significantly lower in the ALS group compared with that in the control group (P = 0.00864), and showed a significant positive correlation with scores on the ALSFRS-R, and a significant negative correlation with the DPR. CONCLUSIONS: In the present study, we reveal for the first time that angiotensin II levels in the CSF from patients with ALS are significantly reduced and significantly associated with disease severity and progression rate. These findings suggest that reduced levels of intrathecal angiotensin II may play a role in ALS.

Reduction of angiotensin II in the cerebrospinal fluid of patients with multiple sclerosis.

We previously demonstrated that angiotensin II acts as a crucial neuroprotective factor after neural injury through angiotensin II type-2 (AT2) receptor signaling. Although the pathway is known to play an important role in the development of experimental autoimmune encephalomyelitis, cerebrospinal fluid (CSF) angiotensin II levels in patients with multiple sclerosis (MS) have never been studied. To clarify the significance of angiotensin II in MS, we assayed angiotensin II concentrations using an established enzyme-linked immunoabsorbent assay in CSF samples from patients with MS (n = 21), patients with inflammatory neuropathies (IN) (n = 23) and control individuals who did not have either of the neurological diseases or any other disease that might affect the angiotensin II levels in the CSF (control) (n = 24). Angiotensin II levels in the CSF were 3.79 +/- 1.54 pg/ml in the MS group, 5.13 +/- 2.27 pg/ml in the IN group and 6.71 +/- 2.65 pg/ml in the control group. The angiotensin II levels in the CSF of the MS group were significantly lower than in the control group (p = 0.00057). Angiotensin II concentration in the CSF tended to have a negative correlation with the Kurtzke's Expanded Disability Status Scale scores during MS relapse (p = 0.0847). These findings suggest that reduced levels of intrathecal angiotensin II may be related to the abnormal neural damage and repair processes in MS.

Characterization of dental pulp stem cells of human tooth germs.

In previous studies, human dental pulp stem cells (hDPSCs) were mainly isolated from adults. In this present study, we characterized hDPSCs isolated from an earlier developmental stage to evaluate the potential usage of these cells for tissue-regenerative therapy. hDPSCs isolated at the crown-completed stage showed a higher proliferation rate than those isolated at a later stage. When the cells from either group were cultured in medium promoting differentiation toward cells of the osteo/odontoblastic lineage, both became alkaline-phosphatase-positive, produced calcified matrix, and were also capable of forming dentin-like matrix on scaffolds in vivo. However, during long-term passage, these cells underwent a change in morphology and lost their differentiation ability. The results of a DNA array experiment showed that the expression of several genes, such as WNT16, was markedly changed with an increasing number of passages, which might have caused the loss of their characteristics as hDPSCs.

Frequencies of PRNP gene polymorphisms in Vietnamese dairy cattle for potential association with BSE.

Summary Since 2004, significant associations between bovine spongiform encephalopathy (BSE) susceptibility in cattle and frequencies of insertion/deletion (ins/del; indel) polymorphisms within the bovine prion protein gene (PRNP) have been reported. In this study, we investigated the frequencies of indel polymorphisms within two variable sites, a 23-bp indel polymorphism in the promoter region (23indel) and a 12-bp indel polymorphism in intron 1 region (12indel), in the PRNP in 206 Vietnamese dairy cattle and seven Japanese BSE-affected cattle. In Vietnamese dairy cattle, the frequency distributions of del allele and del/del genotypic polymorphisms in the 23indel site, which are thought to be associated with BSE susceptibility, were significantly higher, whereas the frequencies of del allelic and del/del genotypic polymorphisms in the 12indel site, which have been reported to confer BSE susceptibility, were significantly lower. We have provided evidence that Vietnamese dairy cattle have a unique genetic background in the PRNP gene in comparison with cattle or sires previously reported in other countries.

Species-specificity of a panel of prion protein antibodies for the immunohistochemical study of animal and human prion diseases.

Monoclonal antibodies to the prion protein (PrP) have been of critical importance in the neuropathological characterization of PrP-related disease in men and animals. To determine the influence of species-specific amino-acid substitutions recognized by monoclonal antibodies, and to investigate the immunohistochemical reactivity of the latter, analyses were carried out on brain sections of cattle with bovine spongiform encephalopathy, sheep with scrapie, mice infected with scrapie, and human beings with Creutzfeldt-Jakob disease (CJD) or Gerstmann-Sträussler-Sheinker disease (GSS). Immunoreactivity varied between the antibodies, probably as the result of differences in the amino-acid sequence of the prion protein in the various species. Some monoclonal antibodies against mouse recombinant PrP gave strong signals with bovine, ovine and human PrP(Sc), in addition to murine PrP(Sc), even though the amino-acid sequences determined by the antibody epitope are not fully identical with the amino-acid sequences proper to the species. On the other hand, in certain regions of the PrP sequence, when the species-specificity of the antibodies is defined by one amino-acid substitution, the antibodies revealed no reactivity with other animal species. In the region corresponding to positions 134-159 of murine PrP, immunohistochemical reactivity or species-specificity recognized by the antibodies may be determined by one amino acid corresponding to position 144 of murine PrP. Not all epitopes recognized by a monoclonal antibody play an important role in antigen-antibody reactions in immunohistochemistry. The presence of the core epitope is therefore vital in understanding antibody binding ability.

Relationship between oxygenation in inactive biceps brachii muscle and hyperventilation during leg cycling.

Inactive forearm muscle oxygenation has been reported to begin decreasing from the respiratory compensation point (RCP) during ramp leg cycling. From the RCP, hyperventilation occurs with a decrease in arterial CO2 pressure (PaCO2). The aim of this study was to determine which of these two factors, hyperventilation or decrease in PaCO2, is related to a decrease in inactive biceps brachii muscle oxygenation during leg cycling. Each subject (n = 7) performed a 6-min two-step leg cycling. The exercise intensity in the first step (3 min) was halfway between the ventilatory threshold and RCP (170+/-21 watts), while that in the second step (3 min) was halfway between the RCP and peak oxygen uptake (240+/-28 watts). The amount of hyperventilation and PaCO2 were calculated from gas parameters. The average cross correlation function in seven subjects between inactive muscle oxygenation and amount of hyperventilation showed a negative peak at the time shift of zero (r = -0.72, p<0.001), while that between inactive muscle oxygenation and calculated PaCO2 showed no peak near the time shift of zero. Thus, we concluded that decrease in oxygenation in inactive arm muscle is closely coupled with increase in the amount of hyperventilation.

Interacting molecule of AT1 receptor, ATRAP, is colocalized with AT1 receptor in the mouse renal tubules.

The renin-angiotensin system in the kidney plays a critical role in the regulation of renal hemodynamics and sodium handling through the activation of vascular, glomerular and tubular angiotensin II type 1 (AT1) receptor-mediated signaling. We previously cloned a molecule that specifically bound to the AT1 receptor and modulated AT1 receptor signaling in vitro, which we named ATRAP (for AT1 receptor-associated protein). The purpose of this study is to analyze the renal distribution of ATRAP and to examine whether ATRAP is co-expressed with the AT1 receptor in the mouse kidney. We performed in situ hybridization, Western blot analysis, and immunohistochemistry to investigate the expression of ATRAP mRNA and protein in the mouse kidney. The results of Western blot analysis revealed the ATRAP protein to be abundantly expressed in the kidney. Employing in situ hybridization and immunohistochemistry, we found that both ATRAP mRNA and the protein were widely distributed along the renal tubules from Bowman's capsules to the inner medullary collecting ducts. ATRAP mRNA was also detected in the glomeruli, vasculature, and interstitial cells. In all tubular cells, the ATRAP protein colocalized with the AT1 receptor. Finally, we found that the dietary salt depletion significantly decreased the renal expression of ATRAP as well as AT1 receptor. These findings show ATRAP to be abundantly and broadly distributed in nephron segments where the AT1 receptor is expressed. Furthermore, this is the first report demonstrating a substantial colocalization of ATRAP and AT1 receptor in vivo.

Sensitivity to cisplatin determined by the histoculture drug response assay and clinical response of endometrial cancer.

This study investigated the value of the in vitro histoculture drug response assay (HDRA) for predicting the efficacy of chemotherapy in patients with endometrial cancer. Specimens were obtained from 115 patients with endometrial cancer treated at Keio University Hospital between 1994 and 2002. Tumor fragments were cultured on collagen sponge gel with cisplatin for 7 days, and cell viability was assessed. The cutoff value of the 50% inhibitory concentration of cisplatin was set at 23 microg/mL. Sensitivity of stage III or IV disease to chemotherapy was investigated, and differences of 5-year progression-free survival between patients with sensitive and resistant tumors were evaluated by the Kaplan-Meier method. Tumors were evaluable in 93.0% of patients (107/115). Among 38 patients in stages III or IV, 23 received chemotherapy containing cisplatin. Seven sensitive tumors did not recur, while recurrence/progression occurred within 6 months in 8/16 patients with tumors showing low sensitivity. Among stages III and IV patients, there was a significant difference of 5-year progression-free survival (P < 0.05) between those with tumors showing high or low sensitivity. Accordingly, the HDRA may predict the efficacy of chemotherapy for endometrial cancer.

Chemosensitivity testing of ovarian cancer using the histoculture drug response assay: sensitivity to cisplatin and clinical response.

Despite cytoreductive surgery and chemotherapy, the prognosis of advanced ovarian cancer is still poor. Predicting the chemosensitivity of tumors might improve the outcome. Therefore, we investigated the clinical value of the histoculture drug response assay for ovarian cancer. Tumor specimens were cultured for 7 days on collagen gel sponge in medium containing cisplatin, and the 50% inhibitory concentration was determined by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide assay. Then the in vitro sensitivity to cisplatin was compared with the clinical response and survival. Apoptosis of tumor cells was also investigated. Among 173 ovarian cancer patients, 164 were evaluable by the assay, and 29 patients had measurable lesions for which the clinical response could be determined. The 5-year survival rate was significantly higher in patients with chemosensitive tumors than in those with chemoresistant tumors when the cutoff value was set at a 50% inhibitory concentration of 25 microg/mL and the accuracy of the assay was 82.8% (24/29). As chemosensitivity to cisplatin became greater, the number of apoptotic cells also increased. This chemosensitivity assay may help predict the clinical response to cisplatin-based chemotherapy, thus improving the survival of ovarian cancer patients.

Bovine posterior pituitary extract stimulates prolactin release from the anterior pituitary gland in vitro and in vivo in cattle.

It has been reported that the posterior pituitary (PP) gland contains a potent, unknown prolactin (PRL)-releasing factor (PRF) in rats. PRFs are assumed to be produced in neurones located within the hypothalamus, and to be peptidergic in nature. However, little is known about PRFs in domestic animals. To characterize the PRF in the PP of domestic animals, the present study examined the PRL-releasing activity of an acidic extract from bovine PP (bPP) in vitro and in vivo in cattle. First, the PRL-releasing effect of bPP extract was compared with that of PRL-releasing peptide (PrRP), and thyrotropin-releasing hormone (TRH) from cultured bovine anterior pituitary cells. The extract significantly increased PRL concentrations in the culture medium, at doses of 0.002 and 0.02 eq./ml (one eq. is the PP extract from one animal), compared with the control (p < 0.05). PrRP failed to stimulate the release of PRL. TRH significantly increased PRL concentrations in the culture medium, at doses from 10(-9) to 10(-7) M, compared with the control (p < 0.05). The rate of increase in the PRL concentration, by 0.02 eq./ml bPP extract, was significantly greater than that in TRH (p < 0.05). Secondly, plasma PRL responses to the intravenous (i.v.) injection of bPP extract (0.5 eq./head), PrRP [3.59 mug/kg body weight (BW)], TRH (1 mug/kg BW), and a dopamine receptor antagonist (sulpiride, 0.1 mg/kg BW), were examined in calves. PrRP failed to stimulate PRL release; however, plasma PRL increased immediately following the injection of bPP extract, TRH and sulpiride. The PRL-releasing effect of i.v. injections of TRH and sulpiride was more potent than that of bPP extract. Finally, plasma PRL responses to the intra-hypothalamic injection of bPP extract were examined in calves. The intra-hypothalamic infusion (arcuate nucleus) of 0.0625 eq./head of bPP extract strongly stimulated PRL release in calves (p < 0.05). The present results show that PP contains a physiologically potent PRF in cattle.

Relationship between maximal oxygen uptake and oxygenation level in inactive muscle at exhaustion in incremental exercise in humans.

The aim of the present study was to determine whether the oxygenation level in an inactive muscle during an incremental exercise test, determined by near-infrared spectroscopy, influences the maximal oxygen uptake (Vo2max). The oxygenation level at the onset of incremental exercise was higher than that at rest and started to decrease at a high power output. A minimal level was observed at exhaustion during incremental exercise. Vo2 increased linearly after some delay, and the rate of increase in Vo2 was greater at a higher power output. Heart rate increased linearly after the time delay, and the rate of increase in heart rate did not change. There was a significant correlation between Vo2max and oxygenation level in inactive muscle at exhaustion (r=-0.89). We therefore concluded that the oxygenation level in inactive muscle at exhaustion during incremental exercise is associated with an individual difference in Vo2max.

Experimental transmission of abnormal prion protein (PrPsc) in the small intestinal epithelial cells of neonatal mice.

Using an immunohistochemical method, we attempted to detect the transmission of abnormal prion protein (PrPsc) to the enterocytes of the small intestine of neonatal mice by oral exposure with sheep brain affected by scrapie. Five 1-day-old neonatal mice were exposed by oral inoculation to the homogenized brain of a scrapie-affected sheep. In the small intestine of all mice 1 hour after inoculation, immunoreactivity with antinormal prion protein (PrPc) antibody was seen in the cytoplasm of villus enterocytes. This finding suggests transmission of abnormal PrPsc into the cytoplasm of enterocytes. In control mice treated with normal sheep brain, no PrPc signal was seen in enterocytes of the small intestine. Immunopositivity for neurofilament protein and glial fibrillary acidic protein was seen in the cytoplasm of enterocytes of mice inoculated with scrapie and normal sheep brain. This suggests that the enterocytes of neonatal mice can absorb PrPsc and other macromolecular proteins of the sheep brain affected by scrapie and may be more important than previously thought as a pathway for PrPsc transmission in neonatal animals.