Biomedical subjects
Publications and source records attributed to N Murakami.
The carba analogue, in which a methylene group is substituted for the oxygen atom linked to C-15, and 20-deoxo analogue of arenastatin A, a potent cytotoxic spongean depsipeptide, were synthesized. Both analogues lacking the 15,20-ester function, which was easily metabolized in serum, showed good stability in serum as well as moderate cytotoxic activity against KB cells and better solubility.
We examined whether corticotropin-releasing factor (CRF) was involved in orexin-induced grooming and face-washing behaviors, and whether orexin was involved in the stress reaction. Administration of alpha-helical CRF, CRF antagonist, alone had no behavioral effect, but it blocked the orexin-induced grooming and face-washing behaviors in rats. The level of corticosterone increased in a dose-dependent manner 15 min after icv injection of orexin, and it remained high for at least 60 min. In 2-month-old rats, 1 h of immobilization stress increased orexin mRNA levels, but not the melanin-concentrating hormone (MCH) mRNA, in the lateral hypothalamic area (LHA). In 6-month-old rats, 30 min of cold stress increased the expression of orexin mRNA in the LHA. Unlike in the 2-month-old rats, immobilization stress did not change orexin mRNA expression in 6-month-old rats. These results suggest that CRF is involved in orexin-induced behaviors, and that orexin may play an important role in some stress reactions.
Agouti protein and agouti-related protein (AGRP) antagonize alpha-melanocyte-stimulating hormone that binds to and activates the melanocortin-4 receptor (MC4-R) in the hypothalamus, thereby stimulating food intake. Melanin-concentrating hormone (MCH) and orexin are orexigenic peptides that specifically are synthesized in the lateral hypothalamus. MCH gene expression was augmented in A(y)/a (agouti) mice which overexpress agouti protein, but orexin mRNA was not. AGRP administered intracerebroventricularly into wild-type rats augmented MCH but not orexin gene expression. Also, SHU9119, a peptidergic antagonist of MC4-R, increased only MCH mRNA. These findings indicate that interruption of signaling at MC4-R activates the MCH but not the orexin gene. The biosyntheses of MCH and orexin are regulated through different pathways.
The telescoping anastomotic technique was carried out four times on the rat femoral artery in order to examine whether the technique could safely be used three to four times for repair of an artery that was injured at two different sites. In addition, the technique was repeated five and six times to determine the maximum number of anastomosis that could be performed on an artery and to clarify problems of the telescoping anastomosis. In the rats in which the anastomosis was carried out four and five times, 100% patency was obtained, while the first occlusion occurred in a graft on which the anastomosis was repeated six times. The telescoping technique appeared to safely be used three or four times for repair of an artery that had been divided at two sites if tension of the repaired vessel was kept low by the grafting, and torsion of the graft and deformities of the inserted vessel were minimal.
We present a patient whose ectopic calcification following deep posterior compartment syndrome was studied by electron microscopy, chemical analyses, and X-ray diffraction. The patient complained of a toe flexion deformity following a tibial fracture which he sustained 18 years earlier. Damage to the peroneal artery was demonstrated by magnetic resonance angiography, suggesting that the patient had had deep posterior compartment syndrome in the past. A large radiopaque mass, identified in the flexor hallucis longus muscle by radiographs and computed tomography, was resected, resulting in a dramatic improvement of the toe deformity. The resected material was analyzed in detail. It included no osseous tissue, and was not birefringent under a polarizing microscope, being compatible with ectopic calcification rather than ossification. On electron microscopy the material was found to be an assembly of tiny rods. Chemical and X-ray diffraction analyses suggested a carbonate-containing apatite as the most probable substance.
Expression of two myogenic regulatory factors, MyoD and myogenin, was studied in regenerating muscles of dystrophic mice and compared to a chemically induced regeneration process. First, the distribution of the two proteins was determined immunohistochemically at various time points after single administrations of a local anaesthetic, bupivacaine hydrochloride, which causes myonecrosis followed by regeneration. Detectable levels of MyoD appeared at 18 h and the expression reached their maximum levels at 48 h after the injection, which coincide with the stage when satellite cells are activated and start to proliferate. Myogenin became detectable in 24 h and its expression reached its highest level at 72 h after injection when newly formed myotubes appeared. The two genes were also expressed in the dystrophic muscles from dy and mdx mice which exhibit dystrophic pathological features but are associated with different phenotypes. In mdx mice the two genes were expressed at reasonably high levels in parallel with the active regenerating process, whereas in dy mice MyoD and myogenin expressions decreased as fibrosis progressed. However, MyoD was relatively more strongly expressed in the larger mature myotubes of dy mice than in those of mdx mice, suggesting prolonged regenerative activity. In dy and mdx mice, MyoD and myogenin were expressed in different quantities, indicating that these animals have distinct regenerating activities. Our findings confirm that expression of both MyoD and myogenin genes is necessary in the regenerative process for the proliferation of satellite cells (myoblasts) and for the development of early regenerating fibers (myotubes) even in dystrophic muscles.
We investigated the effect of chronic, 10-week spontaneous wheel running (SWR) exercise on stress-induced cardiovascular responses in free-moving male rats, using a biotelemetry system. During cage-switch stress or immobilization stress, blood pressure and heart rate were significantly increased in both the SWR (P<0.001 for each stress) and control groups (P<0.001 for each stress). However the blood pressure response was attenuated significantly in the SWR group (P<0.001) during cage-switch stress, and the blood pressure and heart rate responses were attenuated significantly in the SWR group (P<0.0001 and 0.01, respectively) during immobilization stress. The plasma norepinephrine (NE) response induced by immobilization stress tended to be attenuated in the SWR group, but the groups showed no significant differences in the plasma NE and epinephrine (E) responses to both stresses. These results suggest that daily SWR in rats has beneficial effects in suppressing excessive blood pressure and heart rate responses induced by two different types of stress. The mechanisms responsible for the greater resistance to these stresses in the SWR rats should be investigated further.
The purpose of the present study was to investigate whether central beta-adrenoceptors are involved in stress-induced cardiovascular responses in rats. Using a biotelemetry system, blood pressure and heart rate were measured at rest and during stress induced by immersion in 1 cm-deep water. Intracerebroventricular (i.c.v.) injections of a nonselective beta-adrenoceptor antagonist, DL-propranolol (5 or 50 microg), significantly and dose dependently attenuated the tachycardia induced by water immersion stress (drug-induced reduction of tachycardia at 5 min after the start of stress: 61.4 +/- 13.2% for 5 microg, 72.5 +/- 8.2% for 50 microg). The same doses of DL-propranolol had no effect on the resting heart rate. Injection (i.c.v.) of a lower dose (5 microg) of D-propranolol--which has a lower potency as a beta-adrenoceptor antagonist than DL-propranolol, but a similar local anesthetic, membrane-stabilizing activity--did not attenuate the stress-induced tachycardia, although a higher dose (50 microg) did. Intravenous administration of DL-propranolol (5 or 50 microg) significantly attenuated the stress-induced tachycardia (drug-induced reduction of tachycardia at 5 min after the start of stress: 20.0 +/- 7.5% for 5 microg, 42.4 +/- 3.4% for 50 microg). However, the attenuation was much smaller than in the i.c.v. DL-propranolol-injected group. The i.c.v. injection of the 50 microg dose of DL-propranolol significantly augmented both the resting blood pressure and the pressor response to water immersion stress, whereas the lower dose (5 microg) had no effect. The i.c.v. injection of 50 microg D-propranolol also augmented, although not significantly, the resting blood pressure and the pressor response to stress. These results suggest that central beta-adrenoceptors are involved in the tachycardia induced by water immersion stress in rats.
A cerebellar neoplasm in an 8-month-old boy is reported. While this tumour was composed of small cells and had regions resembling desmoplastic medulloblastoma, it showed ultrastructural neuronal characteristics including bundles of microtubules in the cell processes, numerous synaptic vesicles, and occasional abortive or complete synapses. These characteristic features warranted the diagnosis of a neuroblastoma of the cerebellum. The nature of this rare intraparenchymal tumour in infants is also briefly discussed.
5-epi, 10-epi, 8-Deethyl, and 10-demethyl analogues of callystatin A, a potent cytotoxic spongean polyketide, were synthesized to elucidate structure-requirement for cytotoxic potency. Inversion of the asymmetric center at C-10 in callystatin A minimally affected the activity, while lack of the 10-methyl group in callystatin A decreased cytotoxicity. In addition, the C-5 epimer and the 8-deethyl analogue of callystatin A showed weaker cytotoxicity.
The antimalarial activity of the O-acylated bruceolide derivative, 3,15-di-O-acetylbruceolide, was evaluated against Plasmodium berghei in vivo. The concentration of 3,15-di-O-acetylbruceolide required for 50% suppression (ED50) of P. berghei in mice was 0.46 +/- 0.06 mg/kg/day, whereas bruceolide was only half as effective as 3,15-di-O-acetylbruceolide. Two antimalarial drugs used clinically, chloroquine and artemisinin, demonstrated only low activity corresponding to 1/4 and 1/12 of the ED50 value of 3,15-di-O-acetylbruceolide, respectively. These results may be helpful in the design of better chemotherapeutic bruceolides against falciparum malaria.
Aims: patients with liver cirrhosis exhibit abnormal fuel metabolism, including increased fat and decreased glucose oxidation. Such altered energy metabolism is similar to that observed after starvation and could lead to malnutrition. We therefore studied whether nocturnal energy supplementation might improve the fuel metabolism in cirrhotic patients. Methods: 12 cirrhotic patients and 14 healthy controls participated in this study. Subjects in the two groups ate isonitrogenous (1.2 g/kg/day) and isocaloric (35 kcal/day) diets for 1 week before and during the study. On day 1 of the study, indirect calorimetry was carried out in the morning after an overnight fast. The next morning, the same measurement was performed after the patients took a liquid nutrient (Ensure Liquid(R), 250 kcal) at 23:00 on day 1. Respiratory quotient (RQ), resting energy expenditure (REE), and substrate oxidation rates of glucose (% CHO), fat (% FAT) and protein were estimated from measured VO(2), VCO(2) and urinary nitrogen. Results: Significant decreases in RQ, and % CHO and a significant increase in % FAT were observed at baseline in cirrhotic patients as compared with controls. After the nocturnal energy supplementation, RQ, % CHO and % FAT in cirrhotic patients were significantly recovered, ending at levels close to normal. Conclusions: These results suggest that nocturnal energy supplementation could be useful to correct abnormal fuel metabolism and to prevent malnutrition in cirrhosis.
A case of polymyositis associated with primary cytomegalovirus infection in a 17-y-old girl is reported. The girl exhibited fever, sore throat, progressive myalgia and muscle weakness with elevated creatine kinase, atypical lymphocytosis and myopathic features in the electromyogram. Histopathologically, biopsied muscle met the criteria for polymyositis. Primary cytomegalovirus infection was proven by seroconversion of IgG as well as IgM antibodies. This is the first report of an association between cytomegalovirus infection and polymyositis.
We present a case of late-onset ulnar tunnel syndrome following a Colles fracture. The nerve palsy was caused by a vascular branch that stretched over the ulnar head, compressing the nerve and generating friction against the ulnar head when the forearm was rotated. This is the first report of such a pathomechanism.
Pituitary folliculo-stellate (FS) cells were able to modify the effect of activin-A on gonadotropes through the paracrine factor, follistatin. The present study was aimed to examine whether a hypothalamic peptide, pituitary adenylate cyclase activating polypeptide (PACAP), could be a regulator of this paracrine interaction. Co-culture of FS cell-originated cell line TtT/GF cells with rat anterior pituitary cells showed faint inhibitory effect on the stimulatory action of activin-A on FSH secretion. When PACAP was added to the culture during the co-culture period, however, the presence of TtT/GF cells caused significant suppression of the effect of activin-A on FSH secretion. Conditioned-media (CM) from TtT/GF cells, obtained by incubation of TtT/GF cells in the presence or absence of PACAP, were next added to the cultures of anterior pituitary cells alone. CM from TtT/GF cells without PACAP treatment revealed slight, but not significant, suppressive effect on activin-induced increases in FSH secretion and the percentage of FSH cells. Meanwhile, CM from PACAP-treated TtT/GF cells attenuated both effects of activin-A. Furthermore, the inhibitory effect of the CM was neutralized when follistatin antibody was present in the culture. These results suggest that PACAP is able to regulate the paracrine action of FS cells on pituitary gonadotropes. Besides expressing direct actions on pituitary endocrine cells, PACAP may have roles as a regulator of cell-to-cell interactions within the pituitary gland.
Chipmunks that had been housed at 22 degrees C under a light-dark cycle of 14L:10D for at least one year were exposed to a short photoperiod (10L:14D) and low temperature to induce unseasonable hibernation. We were able to induce hibernation at any time of year and there was no significant difference in the duration of the hibernation bout, the duration of interbout euthermia and duration of bouts of torpor throughout the year; however entrance into hibernation took about 60 days in summer but only about 30 days in any other seasons. In addition, interbout euthermia predominantly occurred during the light phase in winter, whereas in spring interbout euthermia occurred equally in the light and dark phases. These results suggest that both the circadian and circannual systems are linked to hibernation in chipmunks. Subcutaneous infusion of a serotonin antagonist, para-chlorophenylalanine (PCPA), facilitated entrance into and interrupted hibernation in aroused and hibernating chipmunks in summer, respectively. On the other hand, opioid antagonist, naloxone, did not affect hibernation, but extended the period of interbout euthermia. These results suggest that the role of serotonin in entrance into and maintenance of hibernation in chipmunks is independent of the circannual system, and that opioid system may not be involved in hibernation in chipmunks.
Activin-A induces increases in FSH secretion, as well as the number of immunoreactive FSH cells, in cultured rat pituitary cells. In this study, we examined whether mechanisms involved in these two actions of activin-A are identical or not, with respect to the involvement of cellular proliferation and of Ca2+-dependent signaling pathways. Treatment with activin-A (25 ng/ml) for 48 h caused increases in the number of cultured rat anterior pituitary cells that incorporated BrdU, a thymidine analog. The stimulatory effects of activin-A on FSH secretion and on the percentage of immunoreactive FSH cells were, however, not inhibited by the presence of the mitotic inhibitor cytosine arabinoside. On the other hand, the stimulatory effect of activin-A on the percentage of immunoreactive FSH cells was completely blocked in the presence of the Ca2+/calmodulin kinase inhibitor KN-62 or the L-type Ca2+ channel blocker nicardipine. Neither of these inhibitors, however, revealed significant influence on the effect of activin-A on FSH secretion. These results suggest that activin-A exhibits its dual effect on FSH cells without causing cellular proliferation. Furthermore, activin-A appears to induce increases in FSH secretion and enlargement of FSH cell population through distinct intracellular signaling pathways, the former through Ca2+-independent and the latter through Ca2+-dependent mechanisms.
We have experienced two cases of unresectable advanced gastric cancer effectively treated by chemo-immunotherapy. One case was of a 68-year-old male patient diagnosed as having inoperable advanced gastric cancer with liver and lung metastasis. This patient was treated by combined chemo-immunotherapy of MMC 10 mg/M, 5'-DFUR 800 mg/day and OK-432 5 KE/2W. At 6 months later, a computed tomography (CT) scan and upper gastrointestinal (GI) series revealed that the metastatic liver tumors and stomach lesion were remarkably decreased in size, and endoscopic biopsy confirmed no cancer cells in the stomach lesion. Moreover, the metastatic lung tumor had disappeared on chest X-ray. The other case was of a 68-year-old female patient with unresectable advanced gastric cancer treated by combined administration of MMC 10 mg/M, 5-FU 200 mg/day and OK-432 5 KE/2W. At 2 months after commencing the treatment, there was a reduction in the serum carcinoembryonal antigen (CEA) level. At 6 months later, the CEA had decreased to normal, the primary and metastatic sites had completely disappeared on CT, and endoscopic biopsy confirmed no cancer cells in the stomach lesion. This patient has survived to date for 5 years and 6 months after commencing the treatment. These results suggested that combined chemo-immunotherapy of MMC, antimetabolite, and OK-432 was an effective treatment for unresectable advanced gastric cancer.