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Biomedical subjects

M Nakai

Publications and source records attributed to M Nakai.

At least 19 recordsLinked to original sources
PubMed1995

Efficient gene activation in mammalian cells by using recombinant adenovirus expressing site-specific Cre recombinase.

A recombinant adenovirus (Ad) expressing Cre recombinase derived from bacteriophage P1 was constructed. To assay the Cre activity in mammalian cells, another recombinant Ad bearing an on/off-switching reporter unit, where a LacZ-expression unit can be activated by the Cre-mediated excisional deletion of an interposed stuffer DNA, was also constructed. Co-infection experiments together with the Cre-expressing and the reporter recombinant Ads showed that the Cre-mediated switching of gene expression was detected in nearly 100% of cultured CV1, HeLa and Jurkat cells. These results suggest that the recombinant Ad efficiently expressed functional Cre and offers a basis for establishing a powerful on/off switching strategy of gene expression in cultured mammalian cells and presumably in transgenic animals. The method is also applicable to construction of recombinant Ad bearing a gene the expression of which is deleterious to propagation of recombinant Ad.

Adenoviridae↗
PubMed1995

Detection of vanadyl-nitrogen interaction in organs of the vanadyl-treated rat: electron spin echo envelope modulation study.

ESEEM spectroscopy was applied for the first time to organs of an animal, viz. the kidney and liver of the rat treated with vanadyl sulfate. The aim of this study is to investigate the in vivo coordination structure of vanadyl ions administrated, and to gain information concerning the insulin-mimic activity of vanadium. ESEEM measurements for kidney and liver performed at 77 K have established nitrogen coordination to a certain percentage of vanadyl ion in the organs. The rotios of nitrogen-coordinating vanadyl ion were estimated as 70-80% in the liver, and 50-55% in the kidney. Isotropic portions of the 14N HFC were estimated as magnitude of Aiso approximately 5.0 MHz for liver, and approximately 5.2 MHz for kidney, indicating that the coordinating nitrogen is an amino nitrogen. Coordination of the Lys epsilon-amine or the N-terminal alpha-amine of a protein or (a peptide) to vanadyl ion in vivo is suggested.

Animals↗
PubMed1995

Accelerated evolution in the protein-coding regions is universal in crotalinae snake venom gland phospholipase A2 isozyme genes.

The nucleotide sequences of four genes encoding Trimeresurus gramineus (green habu snake, crotalinae) venom gland phospholipase A2 (PLA2; phosphatidylcholine 2-acylhydrolase, EC 3.1.1.4) isozymes were compared internally and externally with those of six genes encoding Trimeresurus flavoviridis (habu snake, crotalinae) venom gland PLA2 isozymes. The numbers of nucleotide substitutions per site (KN) for the noncoding regions including introns were one-third to one-eighth of the numbers of nucleotide substitutions per synonymous site (KS) for the protein-coding regions of exons, indicating that the noncoding regions are much more conserved than the protein-coding regions. The KN values for the introns were found to be nearly equivalent to those of introns of T. gramineus and T. flavoviridis TATA box-binding protein genes, which are assumed to be a general (nonvenomous) gene. Thus, it is evident that the introns of venom gland PLA2 isozyme genes have evolved at a similar rate to those of nonvenomous genes. The numbers of nucleotide substitutions per nonsynonymous site (KA) were close to or larger than the KS values for the protein-coding regions in venom gland PLA2 isozyme genes. All of the data combined reveal that Darwinian-type accelerated evolution has universally occurred only in the protein-coding regions of crotalinae snake venom PLA2 isozyme genes.

Amino Acid Sequence↗
PubMed1995

Isolation and characterization of the cDNA for pea chloroplast SecA. Evolutionary conservation of the bacterial-type SecA-dependent protein transport within chloroplasts.

We report here the isolation of the cDNA for pea chloroplast SecA. Pea SecA encodes a polypeptide of 1,011 amino acids and shows high sequence similarity with cyanobacterial SecA. Pea SecA was synthesized as a larger precursor and was imported into isolated chloroplasts in vitro. The purified pea SecA, which was expressed in Escherichia coli cells, stimulated the in vitro import of the 33 kDa protein of the oxygen-evolving complex into thylakoids. These results indicate that higher plant chloroplasts contain a bacterial-type SecA protein-dependent system for the intraorganellar protein transport into thylakoids.

Adenosine Triphosphatases↗
PubMed1995

Chemical stimulation of the nucleus tractus solitarii decreases spinal cord blood flow in anesthetized rats.

L-Glutamate was microinjected into the nucleus tractus solitarii (NTS) in anesthetized (chloralose and urethane), paralyzed and artificially ventilated rats, and spinal cord blood flow (SCBF) was determined using a combination of labeled microspheres. Unilateral chemical stimulation of the NTS (n = 13) significantly decreased SCBF in the cervical cord from 43 +/- 6 (mean +/- SEM) to 28 +/- 4 (P < 0.05), in the thoracic cord from 35 +/- 3 to 24 +/- 4 (P < 0.01), and in the lumbar cord from 49 +/- 3 to 40 +/- 3 ml min-1 (100 g)-1 (P < 0.05). The decrease in SCBF was not due to the decrease in arterial blood pressure (ABP) because the SCBF during the chemical stimulation of the NTS was significantly smaller (P < 0.05) than the SCBF during controlled hemorrhagic hypotension (n = 11). Chemical stimulation of the NTS did not affect the reactivity of the spinal cord vessels to hypercapnia (n = 5). Microinjection of the vehicle solution into the NTS had no effects on spinal cord circulation (n = 9). These results suggest that the cell bodies within the NTS may play a role in the control of spinal cord circulation.

Animals↗
PubMed1995

Identification of yeast MAS17 encoding the functional counterpart of the mitochondrial receptor complex protein MOM22 of Neurospora crassa.

MOM22 of Neurospora crassa was suggested to be required for the transfer of mitochondrial precursor proteins from the receptors to the protein translocation machinery. We isolated a yeast mutant the viability of which depended on the expression of the introduced N. crassa MOM22 gene. The mutant cells showed defects in protein import into mitochondria when the cells were depleted of MOM22. By screening for suppressor genes for the mutant, we could identify the yeast gene MAS17 encoding the functional counterpart of MOM22. The MAS17 gene was found to be essential for the viability of yeast cells.

Amino Acid Sequence↗
PubMed1995

The post-transcriptional regulator Rex of the human T-cell leukemia virus type I is present as nucleolar speckles in infected cells.

The rex-encoded protein (Rex) of human T-cell leukemia virus type I (HTLV-I) is responsible for the cytoplasmic accumulation of incompletely spliced mRNAs that encode the virion structural proteins. Rex is known to be located predominantly in the cell nucleoli in transient transfections or in the isolated nuclei of HTLV-I-infected cells. However, precise location of Rex under physiological conditions has not been determined unequivocally. Here we report that Rex is primarily located as intranucleolar speckles in HTLV-I-infected cells, except for a few nucleoplasmic speckles. This is in contrast to the more diffuse nucleolar distribution of the rev-encoded protein (Rev) of human immunodeficiency virus type 1 (HIV-1), the functional homologue to Rex, in HIV-1-infected cells. Accumulation of Rev is associated with disruption of nucleolar structure and cell death, whereas Rex does not have these effects. The difference in distribution of Rex and Rev within the nucleoli may reflect the difference of toxicity toward the host cells. Involvement of the nucleolus in processing of certain mRNAs is also discussed.

Animals↗
PubMed1995

Development of a fistula between an internal mammary artery graft and the pulmonary vasculature following coronary artery bypass grafting: report of a case.

We report herein the rare case of a 56-year-old man who gradually developed congestive cardiac failure 6 months after undergoing coronary artery bypass grafting and was found to have a fistula between the internal mammary artery and the pulmonary artery of the upper lobe diagnosed by selective left internal mammary arteriogram. A second sternotomy was performed and demonstrated dense adhesion between the fissure surrounding the internal mammary artery and the upper lobe, and the fistula was resected. We believe that the patient's increasing cardiac failure was almost certainly caused by coronary seal.

Arterio-Arterial Fistula↗
PubMed1995

A cell line (MCA-B1) derived from a canine oral acanthomatous epulis.

A canine oral acanthomatous epulis cell line designated MCA-B1 was established in culture. Immunohistochemically the cells reacted intensely with anti-keratin antibody and mildly with anti-vimentin antibody. An ultrastructural examination of the cells confirmed their epithelial nature. The modal chromosome number was 72 and the cloning efficiency in soft agar culture ranged from 3.4 to 16.1 per cent with a population doubling time of nine hours. MCA-B1 has since been passaged more than 70 times and maintained in culture for more than a year. Most of the characteristics of the original canine tumour cells were retained in the isolated cell line.

Animals↗
PubMed1995

Comparable sensitivities for detection of HIV-1 reverse transcriptase (RT) and other polymerases by RT assays requiring no radioisotopic materials.

An improved non-radioisotopic (Non-RI) reverse transcriptase (RT) assay with a template-primer-immobilized microtiter plate is described, which has greater sensitivity than the former Non-RI RT assay previously described. Non-RI and commercially available non-radioactive (Non-RA) RT assays were compared for their ability to detect various polymerases. Two RTs from Rous-associated virus 2 (RAV-2) and avian myeloblastosis virus (AMV), one polymerase from Escherichia coli (Pol-I) and one recombinant RT of human immunodeficiency virus type 1 (HIV-1) were assessed. Two HIV-1 samples in a culture supernatant and pelleted virion suspended in Triton X-100 solution were measured. The Non-RI RT assay was one hundred times more sensitive by RAV-2 and Pol-I polymerases, and one thousand times more sensitive by the Non-RA assay than by the AMV RT. The Non-RI RT assay was 10, 16 and 64 times more sensitive than the Non-RA assay for measuring recombinant HIV-1 RT, pelleted virus and virus suspended in culture medium, respectively. To explain the discrepancy, it is shown that free biotin, such as in culture medium, disturbs the assay system of the Non-RA RT assay, but not the Non-RI assay. The present assay can be used to clarify the inhibitory mechanism of an anti-HIV-1 substance.

Animals↗
PubMed1995

A micro-suspension-test for evaluation of disinfectants against human immunodeficiency virus.

We devised a micro-suspension-test to evaluate disinfectants against human immunodeficiency virus type-1 (HIV-1) and confirmed its reliability. Suspensions of persistently HIV-1-infected Molt-4 cells were used as targets of disinfectants and residual infectivity was measured by an infectivity assay: after cocultivation with uninfected Molt-4 cells reverse transcriptase activity (RTA) in the supernatant and giant cell formation (GCF) were monitored. Our new infectivity assay consists of a short-term assay, that is RTA and GCF monitoring on the second day of co-culture, and a long-term assay, that is RTA monitoring up to the 28th day of co-culture. The sensitivity of the short-term assay was 1 x 10(3) infected cells and that of the long-term assay 1 x 10(1) infected cells. All the chemical disinfectants examined in this study showed dose- and time-dependent inactivation of HIV-1. By 5-minute contact with ethanol, glutaraldehyde, formalin, sodium hypochlorite and povidone-iodine, HIV-1 was effectively inactivated at concentrations of 20, 0.01, 5, 0.05 and 0.1%, respectively. Since the micro-suspension-test is easy and sensitive, we recommend it as a method for evaluating disinfectants against HIV-1.

Cells, Cultured↗
PubMed1995

Effects of aging and chronic hypertension on cerebral blood flow and cerebrovascular CO2 reactivity in the rat.

We measured regional cerebral blood flow (rCBF) in young and old Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats by a minimally invasive microsphere technique. Blood flows to the cerebrum, diencephalon, mesencephalon, cerebellum and pons-medulla during normocapnia were determined. To test the ability of the vessels to dilate, rCBF was also measured during hypercapnia. Reactivity to CO2 was calculated as delta rCBF/delta paCO2. In the old SHR, blood flow to the pons-medulla (88 +/- 8 ml/min/100 g, mean +/- SEM) was markedly lower than that in the young SHR (107 +/- 4 ml/min/100 g, p < 0.05), whereas the difference of those values in the old and young WKY rats was slight (0.05 < p < 0.1). There were no differences in the values of blood flow to the cerebrum, diencephalon, mesencephalon or cerebellum between the young and old rats in both species. Cerebrovascular CO2 reactivity was markedly impaired in the old SHR (p < 0.05) compared to that in the young SHR, but the difference in reactivity in the WKY rats was not significant. The results indicate that blood flow to the pons-medulla is reduced in association with age, particularly in the hypertensive animals, and that the ability of the cerebral vessels to dilate is impaired homogeneously by the combination of chronic hypertension and aging.

Aging↗
PubMed1995

Mechanism on insulin-like action of vanadyl sulfate: studies on interaction between rat adipocytes and vanadium compounds.

When rats with streptozotocin (STZ)-induced diabetes were given a daily intraperitoneal (i.p.) injection of VOSO4 (+4 oxidation state of vanadium), their serum glucose dropped from hyperglycemic level to normal level within 2d and serum free fatty acid (FFA) level also dropped to normal level. Vanadium was incorporated in most organs as well as in the adipose tissues, as detected by neutron activation analysis (NAA). The mechanism for the insulin-like action vanadium in terms of FFA release from isolated rat adipocytes was investigated: (1) Vanadyl (IV) and vanadic (III) ions normalize the FFA release in the adipocytes treated with epinephrine; (2) vanadate (V) ion treated with ascorbic acid, cysteine or glucose is effective in normalizing the FFA release but vanadate ion alone has no effect on FFA release; (3) vanadyl ion is incorporated into the adipocytes, while vanadate ion is not, as indicated by ESR spectroscopy; and (4) vanadyl ion can act on the glucose transporter, as indicated by experiments using cytochalasin B which is an inhibitor of this transporter. From these results, the normalization of both serum glucose and FFA levels by vanadyl ion was concluded to be due to the incorporation of vanadyl ion into the adipocytes, in which the metal ion acts on the glucose transporter and induces both the promotion of glucose uptake and the decrease of FFA release form peripheral adipocytes. The vanadyl state was suggested to be a possible pharmacologically active form of vanadium allowing the insulin-like action.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipocytes↗
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↗