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Biomedical subjects

M Nakai

Publications and source records attributed to M Nakai.

At least 181 records · Page 10Linked to original sources
PubMed1995

Experimental infection of pigs with a parvovirus isolated from the diarrheic feces of a pig.

A parvovirus (the H-45 strain) isolated from an outbreak of epizootic diarrhea in swine was examined to observe the infectivity and pathogenecity in swine. The virus infection by intranasal route was demonstrated in each group of 2- and 5-day-old colostrum-deprived pigs, 30- and 100-day-old pigs by virus recovery from the nasal and rectal swabs, and detecting seroconversion. The virus was recovered from rectal swabs up to 14 days after inoculation and from nasal swabs up to 9 days. Uninoculated pigs were infected with the virus by contacting with the inoculated pigs. Between 1 and 5 days after inoculation, the inoculated pigs of 2, 5 and 30 days old developed diarrhea and then all the pigs of 2 days old died, resulting from dehydration. In the pigs died after intranasal inoculation, the virus was recovered mainly from the respiratory and gastrointestinal tracts. One hundred-day-old pigs showed no clinical signs. The pathological change was characterised by congestion and edema with hemorrhage in the epithelium of the small intestines exhibiting additional degeneration and desquamation of the epithelial cells.

Aging↗
PubMed1995

Immunolocalization of 91 kDa ascitic protein in the human placenta.

A 91 kDa protein, sharing antigenicity with a pregnancy-associated antigen, was isolated from the ascitic fluid of a patient suffered from the gynaecological malignant neoplasms. It was revealed in the human placenta by immunocytochemical techniques, and found to be localized in the stroma, including a fibrous network, fibroblasts and the Hofbauer cells of the terminal and stem villi in the first trimester. Immunoreactive staining was also found in macrophage-like cells, presumable the precursor of the Hofbauer cell, in the stem villi of placenta. It is assumed that macrophage-like cells containing the protein would be originated from the extraembryonic mesoderm or blood vessels, and then migrated to the stroma of terminal villi. During the second trimester, the protein was observed in numerous vesicles among the syncytial trophoblasts. The density of these immunoreactive vesicles and the cytoplasm of Hofbauer cells was rapidly increased with gestational stages, whereas it was gradually reduced towards the late-second trimester. The highest labellings occurred at around 17 weeks or later. On the other hand, at term, the protein was mainly observed in numerous villous blood vessels including endothelial cells. In the light of these results, a hypothesis concerning mechanisms of transplacental permeability of the protein by the placental barrier is discussed further.

Ascitic Fluid↗
PubMed1995

[The long-term results of isolated aortic valve replacement with 19 mm prostheses].

Twenty-five patients underwent isolated aortic valve replacement with 19 mm valves (8 cases with St. Jude Medical prostheses, 7 cases with Carpentier Edwards Pericardial prostheses and 10 cases with Björk-Shiley prostheses). Postoperative echocardiography revealed data as follows. Peak pressure gradients (mmHg) were 40.4 +/- 14.4 (mean +/- S.D.) in the SJM group, 23.4 +/- 9.8 in the CEP group and 50.5 +/- 16.7 in the BS group. End-diastolic left ventricular dimension in the BS group and interventricular septum thickness in the CEP group was reduced significantly. All but one case were in NYHA functional class I or II, and clinical improvement was almost satisfactory in all groups. However, in the BS group, 4 cases showed peak pressure gradients more than 50 mmHg. We conclude that 19 mm aortic prostheses in this study can provide satisfactory results. However, as for mechanical valve, it may be undesirable to choose BS prosthesis.

Adult↗
PubMed1995

[Intrasellar arachnoid cyst: a case report].

Intrasellar arachnoid cyst is very rare. We report a case of intrasellar arachnoid cyst. A 44-year-old male was admitted for evaluation of his headache and visual disturbance on August 6, 1993. Neurological examination revealed bilateral decreased visual acuity and visual field defect. Endocrinological examination showed panhypopituitarism. Other neurological findings were normal. X-ray film of the skull showed a ballooning dilation of the sella turcica with thinning of the sellar floor. CT scan showed a cystic lesion with CSF-density occupied the sella. After intravenous administration of contrast medium, the cyst showed no enhancement. MRI showed the intrasellar mass had the same characteristics as the surrounding subarachnoid space. Bilateral carotid angiographies demonstrated that the carotid siphons were stretched and displaced laterally, and the A1 portions of the anterior cerebral arteries were raised. We made a diagnosis of intrasellar cystic lesion. On August 18, the sella turcica was opened via the transsphenoidal rhinoseptal approach. The cyst contained CSF-like fluid, and a part of the cyst wall was resected. The cavity was filled with Gelfoam and the sellar floor was repaired with bone flap. Postoperatively, the patient's visual disturbance improved, but diabetis insipidus appeared and required hormonal replacement. The patient was discharged on September 27 with improvement of visual acuity and visual field. Histological examination demonstrated that the cyst wall consisted of thick arachnoidal cells with fibrous connective tissue. The arachnoidal cells with oval nuclei was stained with epithelial membrane antigen. Symptoms, signs and radiological findings of intrasellar arachnoid cyst are similar to those of various sellar lesions including pituitary adenoma, craniopharyngioma, empty sella, Rathke's cleft cyst, epidermoid et al.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

[Chemohyperthermic peritoneal perfusion and subtotal peritonectomy for peritonitis carcinomatosa in gastroenteric cancer].

A new operative procedure, called subtotal peritonectomy (SP), in combination with chemohyperthermic peritoneal perfusion, was developed for the treatment of peritonitis carcinomatosa in gastrointestinal cancer. SP includes resection of primary lesion, colon, small bowel, spleen, and gall bladder and parietal peritonectomy. Six patients with gastric cancer and two patients with colon cancer underwent these procedures. A great deal of discharge from the peritoneal cavity, an increase in systemic vascular resistance index, and a decrease in central venous pressure represented much decrease in circulatory volume on days 1 to 2 postoperatively. This state improved at 3 to 4 days after operation. Histopathological study revealed multiple peritoneal seedings with negative surgical margins in all patients. There were no related deaths though bleeding, perforation, and abscess occurred in two patients each. One patient died of peritoneal recurrence after one year, but the other have survived.

Adult↗
PubMed1995

[Identification of motor area by transcranial magnetic stimulation using an "eight-figure" coil in patients with motor paralysis].

In patients with motor paralysis, we tried to identify the functional motor area by transcranial magnetic stimulation using an "eight-figure" coil designed by Ueno. Motor evoked potentials (MEPs) were recorded in 7 patients from 50 to 64 years old, and in 5 normal volunteers 26 to 45 years old. They were stimulated at 49 points over an unilateral hand motor area, and at 21 points over a foot motor area, and surface MEPs were recorded on their contralateral thenar muscle and abductor hallucis brevis muscle. In normal volunteers, the optimal eddy current for stimulating the hand motor area was directed anteriorly parallel to the midline, and for stimulating the foot motor area, it was postero-laterally directed with an angle of 45 degrees towards the midline. MEPs could be induced at their muscle contractions during which their thumbs and middle fingers softly touched each other, and their halluxes slightly flexed. In five patients two kinds of amplitude mappings reconstructed from MEPs were obtained at rest or at muscle contraction. A line connecting these two peaks on an amplitude mapping was regarded as an "MEP-motor area". A geographical difference between the MEP-motor area and MRI-motor area (identified by an MRI surface image) was studied at muscle contraction and at rest. In normal subjects the sites of the MEP-motor area and of the MRI-motor area coincided, whereas, in patients with space-occupying lesions near the central sulcus, the MEP-motor areas were located 1 to 2cm posterior to MRI-motor areas.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Identification of the SecA protein homolog in pea chloroplasts and its possible involvement in thylakoidal protein transport.

Recently, we identified the SecA and SecY proteins in the cyanobacterium Synechococcus PCC7942. Antibodies raised against cyanobacterial SecA specifically reacted with a 110-kDa protein of pea chloroplasts, suggesting the presence of SecA in higher plant chloroplasts. A part of the pea secA cDNA was polymerase chain reaction-amplified with degenerated oligonucleotide primers and with pea cDNA as a template. The deduced amino acid sequence shows 62% identity with cyanobacterial SecA and 52% identity with Escherichia coli SecA. Antibodies raised against the pea SecA fragment, which was expressed in E. coli cells from the obtained polymerase chain reaction-amplified cDNA, reacted with the 110-kDa chloroplast protein; the 110-kDa protein was mainly found in the stroma but partly in the thylakoid membrane. The anti-pea SecA IgG inhibited the in vitro import of the 33-kDa protein of the oxygen-evolving complex, but not of the 23-kDa protein of the oxygen-evolving complex, into thylakoids. These results suggest that SecA facilitates transport of a subset of thylakoid lumenal proteins including the 33-kDa protein into thylakoids. We propose that a bacterial-type Sec protein-dependent transport system operates for protein transport into thylakoids in higher plant chloroplasts.

Amino Acid Sequence↗
PubMed1994

Chloroplast protein import. Chloroplast envelopes and thylakoids have different abilities to unfold proteins.

Proteins have to be at least partially unfolded upon passage through the biological membranes. Previous studies with a dihydrofolate reductase fusion protein containing a chloroplast transit peptide showed that stabilization of the tertiary structure of the fusion protein by binding of a ligand, methotrexate, failed to block its translocation across the envelopes, suggesting that chloroplast envelopes have strong activity to unfold proteins [America, T., Hageman, J., Guéra, A., Rook, F., Archer, K., Keegstra, K. & Weisbeek, P. (1994) Plant Mol. Biol. 24, 283-294]. In the present study, we have analyzed in vitro translocation of a fusion protein consisting of the entire plastocyanin precursor and dihydrofolate reductase across the chloroplast envelope membranes and the thylakoid membrane. In the presence of methotrexate, the fusion protein was imported into the stroma but its translocation across the thylakoid membrane was blocked. The fusion protein that bound to the envelope became susceptible to digestion by thermolysin. These results suggest that, while the envelope membranes can unfold the methotrexate-bound fusion protein to allow its passage, the thylakoid membrane cannot unfold the fusion protein that has re-bound to methotrexate in the stroma.

Amino Acid Sequence↗
PubMed1994

Identification and characterization of the sec-A protein homologue in the cyanobacterium Synechococcus PCC7942.

The secA gene product mediates protein translocation across the cytoplasmic membrane in Escherichia coli. We have cloned a gene homologous to secA from the genome of the cyanobacterium Synechococcus PCC7942. The deduced amino acid sequence, 948 amino acids long, shows 43% homology with that of the E. coli secA and 47-48% homology with those of the algal plastid secA genes. Upon subcellular fractionation, the cyanobacterial SecA protein was mainly found as soluble homodimer in the cytosol, but the remaining small but distinct fraction was associated with both the cytoplasmic and thylakoid membranes. The SecA protein likely participates in protein translocation across both the cytoplasmic and thylakoid membranes in cyanobacterial cells.

Adenosine Triphosphatases↗
PubMed1994

Yge1p, a eukaryotic Grp-E homolog, is localized in the mitochondrial matrix and interacts with mitochondrial Hsp70.

Yeast Yge1p, the gene product of YGE1, is a eukaryotic GrpE homolog found recently (Ikeda et al., 1994). We have revealed here that Yge1p is a soluble protein in the mitochondrial matrix. Depletion of Yge1p in yeast cells resulted in accumulation of the precursor of F1-ATPase beta subunit in vivo, suggesting that Yge1p is involved in protein import into mitochondria. Overexpression of Yge1p in the temperature-sensitive mutant strains of mitochondrial hsp70, Ssc1p, caused hypersensitivity to temperature for cell growth, suggesting a genetic interaction between the YGE1 and SSC1 genes. A physical interaction between Yge1p and Ssc1p was directly demonstrated by co-immunoprecipitation of Ssc1p by the anti-Yge1p antibodies. We propose that Yge1p functions in cooperation with Ssc1p in a similar manner as bacterial GrpE with DnaK.

Bacterial Proteins↗
PubMed1994

Medullary cardiovascular center and acute brain swelling.

Acute brain swelling is reported to be due to acute vasodilatation of cerebral vessels. One of the causes of acute brain swelling may be disturbance of central control mechanisms of cerebral vessels. It has been reported that the anatomical location of the area which controls cerebral circulation is related to the area which controls systemic circulation. However, the role of the cardiovascular center on cerebral circulation has not been clear. The present study was, therefore, undertaken to examine the effects of chemical stimulation of the medullary cardiovascular center [nucleus tractus solitarius (NTS), ventrolateral depressor area (VLDA), and ventrolateral pressor area (VLPA)] on cerebral circulation. In anesthetized, paralyzed and artificially ventilated rats, the neurons in the NTS, VLDA, and VLPA were chemically stimulated and the cerebral blood flow (CBF) was determined using labeled microspheres. The CBF decreased significantly and the cerebrovascular resistance (CVR) increased significantly by chemical stimulation of the NTS, VLDA, and VLPA. These results suggest that the neurons within the NTS, VLDA, and VLPA control cerebral vessels vasoconstrictively. There is a possibility that the dysfunction of the NTS, VLDA, and VLPA may cause acute brain swelling.

Animals↗
PubMed1994

Dysfunction of the medullary cardiovascular center may cause acute spinal cord swelling.

Acute brain swelling is well known to be acute vasodilatation of cerebral vessels and sometimes results from brain injury. One of the causes of acute brain swelling may be disturbance of central control mechanisms of cerebral vessels. However, the presence of acute spinal cord swelling is little noticed. We present here a possibility that acute spinal cord swelling may be occur following the dysfunction of the cardiovascular center of the medulla. In urethane-anesthetized, paralyzed and artificially ventilated rats, the neurons in the rostral ventrolateral pressor area (VLPA), origin of the sympathetic nerve activities in the brain stem, were chemically stimulated by microinjection of L-glutamate and the spinal cord blood flow (SCBF) was determined using labeled microspheres. The SCBFs of cervical, thoracic, and lumbar cord decreased significantly from 27 +/- 3 (mean +/- S.E.M.) to 20 +/- 2 (p < 0.01), from 22 +/- 1 to 17 +/- 2 (p < 0.05), and from 41 +/- 5 to 26 +/- 3 (p < 0.05) ml.min-1.(100 g)-1, respectively (n = 12). The spinal cord vascular resistances (SCVRs) of cervical, thoracic, and lumbar cord increased significantly from 3.7 +/- 0.4 to 5.0 +/- 0.6 (p < 0.05), from 4.2 +/- 0.2 to 5.9 +/- 0.7 (p < 0.05), and from 2.5 +/- 0.2 to 3.8 +/- 0.4 (p < 0.05) mmHg per [ml.min-1.(100 g)-1], respectively (n = 12). These results suggest that the neurons within the VLPA may play a role in the control of spinal cord circulation. There is a possibility that the dysfunction of the VLPA may cause acute spinal cord swelling.

Animals↗
PubMed1994

Caudal ventrolateral medullary depressor area controls cerebral circulation via rostral ventrolateral medullary pressor area.

The cerebral blood flow (CBF) was determined by radiolabeled microsphere technique in urethane (1.1-1.5 g.kg-1, i.p.) anesthetized Wistar rats. Microinjection of L-glutamate (1.7 nmol) into the ventrolateral medullary depressor area (VLDA) produced a significant (P < 0.01) decrease in CBF from 64 +/- 9 (mean +/- S.E.M.) to 48 +/- 9 ml.min-1.(100g)-1 and a significant (P < 0.01) increase in cerebrovascular resistance (CVR) from 1.7 +/- 0.2 to 2.4 +/- 0.4 mmHg per [ml.min-1.(100g)-1] in the cerebral cortex ipsilateral to the stimulated VLDA side but not in other structures such as brain stem and cerebellum (n = 9). Cervical sympathectomy blocked the decrease in CBF and increase in CVR elicited by chemical stimulation of the VLDA (n = 10). Depression of the ventrolateral medullary pressor area (VLPA) neurons induced by microinjection of muscimol into the VLPA blocked the CBF decrease and CVR increase following chemical stimulation of the VLDA (n = 11). Microinjection of the vehicle solution into the VLDA had no effects on systemic and cerebral circulation (n = 7). These results suggest that a vasoconstrictor pathway to control cerebral vessels involves an excitatory projection from the VLDA to the VLPA and the changes in cerebral circulation are mediated by the cervical sympathetic nerves.

Animals↗
PubMed1994

Morphological changes in the rat Sertoli cell induced by the microtubule poison carbendazim.

Early morphological changes in the rat Sertoli cell induced by the fungicide carbendazim (methyl-2-benzimidazole carbamate; MBC), a metabolite of benomyl, were examined. Adult rats were treated with single doses of MBC (400 mg/kg) or vehicle and examined by light and electron microscopy at 3 hr post-treatment. Sloughing of elongating spermatid clusters was observed in all stages of spermatogenesis, except for Stages III-V. Cleavage occurred near the apical region of the seminiferous epithelium where cytoplasmic processes of the Sertoli cell surround the heads of elongating spermatids. The cleaved cytoplasm remained attached to the sloughed spermatids and ectoplasmic specializations remained undamaged. Intact microtubules were observed in the apical Sertoli cell cytoplasm (including sloughed tissues) but were decreased in the body region, where aggregates of mitochondria were found. Cytoplasm near the cleavage site exhibited rarefaction, which was associated with swollen cisternae of endoplasmic reticulum. It appears that the mechanism of germ cell sloughing induced by MBC treatment involves the disruption of microtubules in the body region of the Sertoli cell, the retraction of cytoplasmic organelles and the swelling of endoplasmic reticulum.

Administration, Oral↗
PubMed1994

Metabolic and non-metabolic cerebrovasomotor mechanisms operational during hypertensive states of different origin in rats.

We attempted to elucidate the vasomotor mechanisms regulating the cerebral circulation of rats under arterial hypertensive states of different origin. Sudden cold exposure elicited a cerebrovasodilator response mediated primarily by an enhanced cerebral metabolic state. The response was not modified by the concomitantly enhanced cerebrovascular sympathetic action. Central inhibition of the baroreceptor reflex, as achieved by chemical inhibition of the caudal ventrolateral medulla, disinhibited a non-metabolic cerebrovasodilator mechanism. However, its action was masked by a concomitantly enhanced sympathetic vasoconstrictor action. Another type of cerebrovasodilator response, also of non-metabolic origin, was elicited by chemical stimulation of the defence area within the periaqueductal grey matter. Thus, the cerebrovasomotor mechanisms are diversely activated so as to cope adequately with the individual conditions imposed on the animals.

Animals↗