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Biomedical subjects

M Nakano

Publications and source records attributed to M Nakano.

At least 199 records · Page 11Linked to original sources
PubMed1999

Increased serum levels and sinusoidal expression of thrombomodulin in acute liver damage.

Thrombomodulin (TM) is a surface glycoprotein of endothelial cells involved in both anticoagulation and antifibrinolysis. In this study, we assessed the clinical significance of TM in acute liver damage by using a rat model induced by intraperitoneal injection of D-galactosamine (Gal-N). Serum TM levels were measured with enzyme immunoassay utilizing rabbit anti-rat TM antibody. Simultaneously, immunohistochemical examination was performed using the same antibody. Serum TM levels increased significantly after the injection of Gal-N compared with preinjection levels, peaking from 48 to 72 hours after injection and normalizing by 168 hours. Changes in parenchymal damage were synchronized with changes of TM, and changes of TM levels mirrored changes of liver weight. In immunohistochemical examination, TM immunoreactivity was observed only on the endothelial surfaces of both the artery and portal vein within Glisson's sheath in controls. After injection of Gal-N, TM immunoreactivity was gradually intensified, especially around the necrotic area and the central veins. These findings disappeared with improvement of parenchymal damage. Both the increase of serum TM levels and intensified TM immunoreactivity in the liver were synchronized with acute liver parenchymal damage induced by Gal-N. These findings on TM are related to endothelial damage with parenchymal necrosis and liver regeneration interacting with both homeostasis of microcirculation and healing of parenchymal damage.

Acute Disease↗
PubMed1999

Transition protein 4 from boar late spermatid nuclei is a topological factor that stimulates DNA-relaxing activity of topoisomerase I.

Transition protein 4 (TP4) from boar late spermatid nuclei, having higher affinity for double-stranded DNA and a local melting activity of DNA, stimulated SV40 DNA-relaxing activity of eukaryotic topoisomerase I at TP4/DNA molar ratios of 6.6-11. A TP4-spermidine mixture stimulated the activity of topoisomerase I much more than spermidine alone, but no more than TP4 alone, and poly-L-arginine did not. These results suggest that TP4 contributes to the chromatin reorganization in the late spermatid nuclei from nucleosomal-type structure with negatively supercoiled DNA to nucleoprotamine structure with no supercoiled DNA.

Animals↗
PubMed1999

Microvasculature of crotaline snake pit organs: possible function as a heat exchange mechanism.

The infrared sensory membranes of the pit organs of pit vipers have an extremely rich capillary vasculature, which has been noted passim in the literature, but never illustrated or studied in detail. We rendered the pit vasculature visible in various ways, namely, by microinjection of India ink, by a combination of ink and succinate dehydrogenase staining, and by making resin casts for scanning electron microscope study. We also used transmission electron microscopy for identifying the types (arterioles, venules, capillaries) of blood vessels. Then we compared the pit vasculature with that of the retina and the dermis. Good visualization of the vasculature was obtained with both ink and resin injection. Arterioles, venules, and capillaries could be distinguished with all methods used. The monolayer vasculature was denser in the pit membrane than in the retina or skin. Each loop of the network enclosed a small number of infrared receptors so that all receptors were in contact with a capillary on at least one side. The forward-looking areas of the pit had a denser network than side-looking areas. Since infrared rays cause nerve impulses by raising the temperature of individual receptors, the capillary network functions not only as a supplier of energy but also as a cooling mechanism to reduce afterimages. Thus the denser network in the forward-looking areas causes these areas to be more sensitive and have better image resolution than the rest of the membrane.

Agkistrodon↗
PubMed1999

Role of IFN-gamma on dissociation between nitric oxide and TNF/IL-6 production by murine peritoneal cells after restimulation with bacterial lipopolysaccharide.

Murine peritoneal exudate cells (PEC) pre-exposed to bacterial lipopolysaccharide (LPS) show augmented nitric oxide (NO) production by LPS restimulation, in contrast to LPS tolerance with reduced production of tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6). Significant amounts of interferon-gamma (IFN-gamma) were detected in the PEC cultures on LPS stimulation, and anti-IFN-gamma antibody suppressed the LPS-induced NO, but not TNF-alpha and IL-6, production. Addition of anti-IFN-gamma antibody to the cultures in the LPS pre-exposure step strongly suppressed the augmented NO production on LPS restimulation. Anti-IL-12 antibody, which suppressed the LPS-induced IFN-gamma production, also suppressed the augmented NO production, as did anti-IFN-gamma antibody. Taken together, we propose the following mechanisms: (1) T and NK cells in PEC produce IFN-gamma by the action of IL-12, which is derived from LPS-stimulated macrophages, and (2) the de novo-produced IFN-gamma activates macrophages to augment NO production on LPS restimulation.

Animals↗
PubMed1999

Expression of a zinc-binding domain of boar spermatidal transition protein 2 in Escherichia coli.

Transition protein 2 (TP2; 137 amino acid residues) from boar late spermatid nuclei has three potential zinc finger motifs in the N-terminal 34 region. Gel shift assays revealed that boar TP2 recognized a CpG island sequence in a zinc-dependent manner. However, there was some nonspecific recognition of the oligonucleotide. Then, we constructed the expression system of zinc-binding domain of TP2 (TP2Z) (residues 1-103) in Escherichia coli. Double-stranded DNA fragments encoding TP2Z were synthesized as 18 fragments with 103 residues, annealed, and cloned into the expression plasmid pET11d. TP2Z was expressed upon induction with 1 mM isopropylthiogalactoside and extracted with acid including 0.71 M 2-mercaptoethanol. TP2Z was purified by ion-exchange chromatography on Fractogel EMD SO(-)(3) and HPLC on Nucleosil 300 7C18 and on Diol-120. Atomic absorption and CD spectroscopy showed that TP2Z bound three atoms of zinc per molecule of the protein and underwent a zinc-dependent conformational change in a manner similar to that for intact TP2. Gel shift assays indicated that TP2Z recognized a CpG island sequence more specifically than intact TP2 and that the specificity is dependent on zinc.

Amino Acid Sequence↗
PubMed1999

Mitral valve repair by Carpentier-Edwards physio annuloplasty ring.

A semi-flexible annuloplasty ring (Physio-ring) was clinically used in 30 cases of mitral valve insufficiency. The Physio-ring has the characteristics in which the anterior section is rigid and has a saddle-shaped curve, while the posterior section is flexible to allow for changes in size and shape of the anulus during ventricular contraction. The patients were aged from 23 to 73 years (mean 53.8 +/- 12.5). The cause of mitral valve insufficiency was degenerative (in 24 patients), rheumatic (2), ischemic (1), endocarditis (1), congenital + degenerative (1), and traumatic (1). On the 6-month post-implant echocardiogram, 96.6% had grade 0 or +1 regurgitation. The effective valve orifice area was 2.61 +/- 0.82 cm2 (n = 19). There was no late death. However, there was 1 (3.3%) hospital death after the patient had received a simultaneous coronary artery bypass grafting, and then developed low output syndrome after surgery. Although there was no device-related complication, hemolysis of undetermined cause was observed in 1 (3.3%) patient. The findings from this study indicated a low incidence of device-related complication, while excellent valvular function was maintained.

Adult↗
PubMed1999

Only limited effects of aminoguanidine treatment on peripheral nerve function, (Na+,K+)-ATPase activity and thrombomodulin expression in streptozotocin-induced diabetic rats.

AIMS/HYPOTHESIS: Aminoguanidine, a potent anti-glycation reagent, is known to be beneficial in experimental diabetic neuropathy. In this study, we explored the mechanisms of how aminoguanidine inhibits neuropathic changes in diabetes and compared its effects with those of insulin treatment. METHODS: Wistar rats, aged 8 weeks, were made diabetic by streptozotocin and given aminoguanidine dissolved in drinking water (1 g/l) for 8 weeks. Effects of daily insulin (protamine-zinc) treatment were also examined for comparison. At the end of the 8 weeks, we examined the peripheral nerve function and (Na+,K+)-ATPase activity and their relation to serum thrombomodulin concentrations that are considered as a marker of endothelial injury. RESULTS: Aminoguanidine treatment reduced the diabetes-induced decrease in tibial nerve conduction velocity by 47% (p < 0.05 vs untreated diabetic rats) and inhibited the loss of sciatic nerve (Na+,K+)-ATPase activity by 54% (p < 0.05 vs untreated diabetic rats). Insulin-treatment of diabetic rats restored these variables by 83% and 75%, respectively (both, p < 0.01 vs untreated diabetic rats). Thrombomodulin concentrations were increased (p < 0.01) in diabetic rats compared with those in non-diabetic controls and unaffected by aminoguanidine treatment. In contrast, the concentrations remained within the normal range in the insulin-treated group. CONCLUSION/INTERPRETATION: Although aminoguanidine treatment improved nerve conduction velocity and (Na+,K+)-ATPase activity, its effects were considerably less than those of insulin and were not apparent in some measures of endothelial cell injury.

Animals↗
PubMed1999

Congenital absence of the portal vein in a boy.

Congenital absence of the portal vein (CAPV) is a malformation that is generally thought to be limited to females. We encountered an 11-year-old boy with this malformation. In 17 previously reported cases of CAPV, 2 were male. Three male patients, including our case, were Abernethy type Ib malformation. They had no associated liver tumour and two had no additional congenital abnormality. Conversely, 13 of the 15 female patients had congenital abnormalities and 6 had liver mass lesions.

Child↗
PubMed1999

Immunohistochemical localization of thrombomodulin in the stratified epithelium of the rat is restricted to the keratinizing epidermis.

The expression and function of thrombomodulin (TM), an endothelial cofactor protein for thrombin-mediated protein C activation, in the epithelium are not fully characterized. This report describes the distribution and localization of TM in the various types of epithelia in the rat by light and electron microscopic immunocytochemistry. TM showed a limited distribution and was expressed by the keratinizing stratified epithelia of the skin, tongue, and esophagus, but was not present on the non-keratinizing epithelia of the vagina, ureter, trachea, stomach, or gut. An identical pattern of TM expression was seen in mucocutaneous junctions, transitional zones from a non-keratinizing stratified epithelium to a keratinizing epithelium at the edge of the eyelid and in the anal canal. As the keratinization of the stratified epithelia proceeded, the staining intensity increased in the transitional zones. Within the keratinizing stratified epithelia, TM staining was limited to the keratinocytes of the spinous layer, the spinous cells. The subcellular localization of TM on the spinous cells was restricted to the plasma membrane facing the intercellular spaces. TM was not detectable on the desmosomes or the two membranes making up the junction, presumably the nexus. The functional significance of TM in keratinizing epithelia is discussed.

Animals↗
PubMed1999

Nitric oxide synthase in the glossopharyngeal and vagal afferent pathway of a teleost, Takifugu niphobles. The branchial vascular innervation.

To examine the presence of nitric oxide synthase (NOS) in the sensory system of the glossopharyngeal and vagus nerves of teleosts, nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) activity and immunoreactivity for NOS were examined in the puffer fish Takifugu niphobles. The nitrergic sensory neurons were located in the ganglia of both the glossopharyngeal and the vagal nerves. In the vagal ganglion, positive neurons were found in the subpopulations for the branchial rami and the coelomic visceral ramus, but not for the posterior ramus or the lateral line ramus. In the medulla, nitrergic afferent terminals were found in the glossopharyngeal lobe, the vagal lobe, and the commissural nucleus. In the gill structure, the nitrergic nerve fibers were seen in the nerve bundles running along the efferent branchial artery of all three gill arches. These fibers appeared to terminate in the proximal portion of the efferent filament arteries of three gill arches. On the other hand, autonomic neurons innervating the gill arches were unstained. These results suggest that nitrergic sensory neurons in the glossopharyngeal and vagal ganglia project their peripheral processes through the branchial rami to a specific portion of the branchial arteries, and they might play a role in baroreception of this fish. A possible role for nitric oxide (NO) in baroreception is also discussed.

Afferent Pathways↗
PubMed1999

Nutritional supply to the cauda equina in lumbar adhesive arachnoiditis in rats.

Laminectomy-induced cauda equina adhesion has been proved by rat experiments and postoperative serial MRI in humans. A degenerative change of the cauda equina has been proved when cauda equina adhesion has been prolonged. Since it has not been reported how the nutritional supply is changed in such a condition, we evaluated the glucose supply to the adhered cauda equina in rats. Wistar rats were divided into the following three groups: the control group which received no operation, the laminectomy group which underwent L5-L6 laminectomy only, and the koalin group which received 5 mg of kaolin on the dorsal extradural space following L5-L6 laminectomy. Based on 3H-methyl-glucose uptake study, we analyzed (1) glucose transport from the intraneural vessels to the nerve tissue, and (2) glucose transport from the cerebrospinal fluid to the nerve tissue. We evaluated the relation between the severity of cauda equina adhesion and 3H uptake into the cauda equina. Cauda equina adhesion was observed in 2 of 12 rats in the control group, in 3 of 12 rats in the laminectomy group, and in 18 of 20 rats in the kaolin group. In the 3H-methyl-glucose uptake study, at 12 weeks the glucose transport to the cauda equina from the vessels increased by 44%, and that from the cerebrospinal fluid decreased by 64% in the kaolin group compared with the control group. In the condition of complete cauda equina adhesion, the glucose transport to the cauda equina from the vessels increased by 53% and that from the cerebrospinal fluid remarkably decreased by 72% compared with the normal cauda equina. Considering the greater nutritional importance of the cerebrospinal fluid in the cauda equina, it is most likely that the impairment of nutritional supply to adhered cauda equina may lead to eventual neural degeneration.

Animal Nutritional Physiological Phenomena↗
PubMed1999

Sequence analysis of RNA-2 of different isolates of broad bean wilt virus confirms the existence of two distinct species.

The complete nucleotide sequence of RNA-2 from a Japanese isolate IP of broad bean wilt virus (BBWV) was determined. The sequence encodes a single large polyprotein, which contains a putative movement protein and two coat proteins (CPs). The 3'-terminal sequences of RNA-2 were also determined for three other Japanese isolates and two ATCC isolates (PV132 and PV176) of BBWV. The CPs of the four Japanese isolates share 86.8-98.0% amino acid sequences homology with one another and 88.3-96.5% with those reported for the isolate PV131 (BBWV-2). However, they have only 57.9-66.2% homology with those of PV132 and PV176 (BBWV-1).

3' Untranslated Regions↗
PubMed1999

Urinary thrombomodulin in patients with rheumatoid arthritis: relationship to disease subset.

In 110 patients with rheumatoid arthritis (RA), the mean (+/- SD) urinary thrombomodulin (TM) concentration was 74.4+/-19.5 ng/mg creatinine (Cre), which was significantly higher than the mean in age-matched healthy controls (49.9+/-10.8 ng/mg Cre; p<0.0001). The mean urinary TM concentration in the RA subset with least erosive disease (LES) was 65.2+/-12.4 ng/mg Cre (n = 41), with more erosive disease (MES) was 77.4+/-20.4 ng/mg Cre (n = 58) and with mutilating disease (MUD) was 92.6+/-20.2 ng/mg Cre (n = 11). TM in the MUD group was the highest of the three subsets (ANOVA, p<0.0001). By contrast, the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) in the MES and MUD groups were not significantly different. Urinary TM levels may allow differentiation of RA subsets, unlike markers of inflammation such as ESR and CRP.

Adult↗
PubMed1999

Heat stress aggravates viral myocarditis in mice.

While a beneficial effect of hyperthermia on viral infection has been hypothesized, there are no data on viral myocarditis in vivo. To investigate whether hyperthermia might attenuate the course or severity of viral myocarditis, we studied the pathological changes in a murine model of viral myocarditis. C3H mice were inoculated i.p. with the encephalomyocarditis virus (500 pfu). They were anesthetized and heated to a body temperature of 42.5+/-0.2 degrees C for 30 min. The latter was performed 4 hr before (n=28, HB) or 4 hr after (n=28, HA) the viral inoculation; results were compared with nonheated, infected controls (n=30, Cont). Cardiac viral titers were recorded on day 3, and the body weight (BW), heart weight (HW) and pathological changes were recorded on days 5 and 10. The incidence of spontaneous mortality on day 10 was significantly higher in the HA group (all deaths occurring by day 7 post-inoculation) as compared with the HB (35%) or Cont (18%) groups. Viral titers in the HA group (n=4) were significantly (P<0.05) higher than those in the Cont (n=7) or HB (n=7) groups (4.11+/-0.54 vs 3.01+/-0.44 and 3.23+/-0.45 LogTCID50/mg, respectively). On day 5, the HW, the BW/HW ratio, and the severity of myocardial necrosis were all significantly higher in the HA than in the Cont and HB groups. To confirm the effect of hyperthermia on the expression of heart shock protein (HSP), immunohistochemical staining was done in the virus-infected hearts. The nucleus and cytoplasm of the injured myocardium in the HA group strongly expressed HSP70, whereas the HB and Cont groups were negative for this protein. In conclusion, induction of hyperthermia after viral inoculation aggravated the viral-induced myocardial necrosis and increased the mortality rate in a murine model of viral myocarditis and induced myocardial heat shock protein 70.

Animals↗
PubMed1999

Comparison of maitotoxin with thromboxane A2 in rabbit platelet activation.

Maitotoxin (MTX), a Ca2+ channel-activating marine toxin, caused shape change followed by aggregation in rabbit platelets, like U46619, a thromboxane A2 analogue. Although both drugs failed to cause aggregation in the absence of external Ca2+, U46619, but not maitotoxin, elicited shape change in the absence of external Ca2+. The observations of platelets with a scanning electron microscope showed that both drugs caused contraction of platelets and extension of pseudopodia (shape change) followed by aggregation with a clot in the presence of Ca2+. It is noteworthy that long term exposure to MTX caused the lysis of platelets in the presence of Ca2+. While U46619 transiently increased the internal Ca2+ concentration ([Ca2+]i), maitotoxin slowly but irreversibly increased [Ca2+]i in an external Ca2(+)-dependent manner. MTX-induced phosphoinositide hydrolysis was totally dependent on the presence of external Ca2+, but U46619-induced phosphoinositide hydrolysis was still observed in the absence of external Ca2+. MTX-induced phosphoinositide hydrolysis was partly inhibited by SK&F96365, a voltage-independent Ca2+ channel antagonist, or by genistein, a tyrosine kinase inhibitor. MTX caused phosphorylation of tyrosine residues of several proteins, like U46619. Thus, MTX is similar to U46619 in functions of Ca2+ mobilization, phosphoinositide hydrolysis and tyrosine phosphorylation, but MTX-induced actions are strictly dependent on the presence of external Ca2+.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1999

Bone marrow stroma from refractory anemia of myelodysplastic syndrome is defective in its ability to support normal CD34-positive cell proliferation and differentiation in vitro.

We examined the supportive function of stromal cells from patients with refractory anemia (RA) of myelodysplastic syndrome (MDS) on CD34-positive hematopoietic cell proliferation and differentiation using a long-term bone marrow culture (LTMC) system. Primary marrow stromal cells were obtained from 11 MDS RA patients and 12 healthy volunteers, and freshly prepared CD34-positive bone marrow cells from a normal subject were inoculated onto the stroma. There seems to be three broad patterns of hematopoietic cell growth in the LTMCs. In one group, hematopoietic cells were maintained at near normal levels (type A). In the second group, the number of hematopoietic cells increased within the first 5-10 days of culture, but declined to low levels at 15-20 days of culture as compared with normal control (type B). In the third group, the incidence of hematopoietic cells steadily declined from the beginning of the culture (type C). Furthermore, apoptotic change of hematopoietic cells was very frequently observed in cultures with the type C stroma, which were especially defective for supporting CD34 + cell proliferation and differentiation. The expression of CD95 on hematopoietic cells was induced by the type C stroma, however, production of fas ligand by the stromal cells was not observed. These findings suggest a lack of hematopoietic supportive function in some cases of MDS RA and also indicate that there is heterogeneity of stromal function among MDS RA patients.

Adult↗
PubMed1999

Effects of a mixture of organisms, Lactobacillus acidophilus or Streptococcus faecalis on delta6-desaturase activity in the livers of rats fed a fat- and cholesterol-enriched diet.

The effect of a mixture of organisms (a probiotic mixture) comprising Bacillus, Lactobacillus, Streptococcus, Clostridium, Saccharomyces, and Candida (10(7-8) colony-forming units/g rice bran of each component) on delta6-desaturase activity in liver microsomes was compared with those of Lactobacillus acidophilus and Streptococcus faecalis. There were four treatment groups. Each group of these rats received rice bran (control), the mixture of organisms, L. acidophilus, or S. faecalis (30 g/kg) along with a fat- and cholesterol-enriched diet for 4 wk. The serum total cholesterol concentration of the group fed the mixture of organisms was reduced by 15-33% compared with the other groups at the end of the 4-wk feeding period (P<0.05). The proportion of palmitic acid in the serum phosphatidylcholine (PC) for the control group was significantly higher than those of the other groups. The proportion of arachidonic acid in the serum PC for the mixed-organism group was also significantly higher than those of the other groups. The proportion of arachidonic acid in the liver PC for the mixed-organism group was significantly higher than those of the control and S. faecalis groups. The ratio of arachidonic acid/linoleic acid was significantly higher in the liver PC of rats fed the mixed organisms compared with the control group (P<0.05). The delta6-desaturase activity in the liver microsomal fraction of the mixed-organism group was significantly higher than those of the other groups. The delta6-desaturase activity correlated positively with the ratio of arachidonic acid/linoleic acid of liver PC, the correlation coefficient (r) being 0.819 (P<0.001). The results indicate that the effect of the mixture of organisms was to increase delta6-desaturase activity and serum arachidonic acid and decrease cholesterol compared to the other organisms and control, but the mechanism whereby the enzyme activity was related to serum cholesterol does not appear to have been explored.

Animals↗