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Biomedical subjects

M Nakai

Publications and source records attributed to M Nakai.

At least 199 records · Page 11Linked to original sources
PubMed1994

Cerebral vasoconstrictive response produced by chemical stimulation of the caudal ventrolateral medullary depressor area is mediated via the rostral ventrolateral medullary pressor area and the cervical sympathetic nerves.

It was investigated that the cerebral blood flow (CBF) decrease response elicited by chemical stimulation of the caudal ventrolateral medullary depressor area (VLDA) is mediated via the rostral ventrolateral medullary pressor area (VLPA) and the cervical sympathetic nerve. The CBF was determined by radiolabeled microsphere technique in urethane (1.1-1.5 g.kg-1, i.p.) anesthetized Wistar rats. (i) Microinjection of L-glutamate (1.7 nmol) into the VLDA produced a significant (P < 0.01) decrease in CBF from 64 +/- 9 (mean +/- SEM) to 48 +/- 9 ml.min-1.(100 g)-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.(100 g)-1] in the cerebral cortex ipsilateral to the stimulated VLDA side (n = 9). (ii) After cervical sympathectomy, L-glutamate was unilaterally microinjected into the VLDA. The CBF and CVR did not change significantly (n = 10). (iii) After depression of the VLPA neurons with muscimol (GABA agonist), L-glutamate was unilaterally microinjected into the VLDA. The CBF and CVR did not change significantly (n = 14). These results suggest that the pathway from the VLDA to control cerebral vessels may be mediated via the VLPA and the cervical sympathetic nerves.

Animals↗
PubMed1994

Effects of microinjection of N-methyl-D-aspartic acid into the nucleus tractus solitarii on cerebral blood flow in anesthetized rats.

N-Methyl-D-aspartic acid (NMDA) (10 pmol in 100 nl of 0.9% sodium chloride solution) was microinjected into the nucleus tractus solitarii (NTS) of urethane-anesthetized, paralyzed and artificially ventilated rats, and cerebral blood flow (CBF) was determined using a combination of labeled microspheres. Moderate hypertension within the upper limit of cerebral autoregulation was induced by blood transfusion in order to measure CBF at normotension. Arterial blood pressure (ABP) was decreased by unilateral microinjection into the NTS in these rats but remained within normotensive range. The CBF in the cerebral cortex ipsilateral to the stimulated NTS significantly (P < 0.01) decreased from 38 +/- 4 (mean +/- S.E.M) to 27 +/- 4 ml.min-1.(100 g)-1(n = 9). The cerebrovascular resistance (CVR) in the cerebral cortex ipsilateral to the stimulated NTS significantly (P < 0.01) increased from 2.6 +/- 0.3 to 4.1 +/- 0.7 mmHg per [ml.min-1.(100 g)-1]. Blockade of NMDA receptors in the NTS with D,L-2-amino-5-phosphonovalerate (AP5, 500 pmol) abolished the CBF decrease and CVR increase responses elicited by microinjection of NMDA into the NTS (n = 9). Blockade of non-NMDA receptors in the NTS with 6,7-dinitro-quinoxaline-2,3-dione (DNQX, 100 pmol) had little effect on the CBF decrease and CVR increase responses elicited by microinjection of NMDA into the NTS (n = 10). Microinjection of the vehicle solution into the NTS had no effects on cerebral circulation (n = 7). Cerebral autoregulation was well maintained at moderate hypertension induced by blood transfusion and at normotension returned from moderate hypertension following controlled hemorrhage (n = 8). These results suggest that the NMDA receptors in the NTS may be involved in the control of cerebral circulation.

2-Amino-5-phosphonovalerate↗
PubMed1994

Systemic and regional haemodynamic responses elicited by microinjection of N-methyl-D-aspartate into the lateral periaqueductal gray matter in anaesthetized rats.

The haemodynamic defence responses were studied by chemically stimulating the lateral periaqueductal gray matter in 27 anaesthetized, artificially ventilated, and paralysed rats. Blood flow was measured by the radiolabelled microsphere method. Microinjection of N-methyl-D-aspartate (1 nmol as 100 nl of a 10-mM solution, delivered over 10 s) into the brain region elicited a distinctive pattern of haemodynamic defence responses. Vasodilation of the hindlimb skeletal muscle tended to be provoked from the caudal third of the periaqueductal gray, whereas vasoconstriction was elicited from the intermediate third. Whichever stimulation was made, however, increases in arterial pressure, heart rate, cardiac output, and total peripheral resistance were consistently provoked. The blood flow was redistributed away from the abdominal viscera. One new finding was that the brain and heart also had their blood flow increased consistently, the former with and the latter without a significant decrease in vascular resistance. As suggested for the classic pattern of haemodynamic defence responses, we consider that the cerebral and coronary circulations may also be involved in coping with the emergency that threatens the animal. The increased cerebral blood flow should be beneficial for ensuring adequate achievement of central processing and organization of the well-coordinated defence reactions. The increased coronary blood flow should help to ensure maintenance of an increased cardiac output striving against the increased total peripheral resistance.

Anesthesia↗
PubMed1994

Cerebrovasodilatation of metabolic and non-metabolic origin elicited by chemical stimulation of the lateral periaqueductal gray matter in anaesthetized rats.

We attempted to elucidate the mechanisms operating in the mediation of the cerebrovasodilator action of the defence area within the periaqueductal gray matter, employing radiolabelled microsphere flowmetry in 50 anaesthetized rats. The caudal two-thirds of this brain region were chemically stimulated with N-methyl-D-aspartate (1 nmol as 100 nl in a 10-mM solution). Besides eliciting a distinctive pattern of haemodynamic defence responses, the stimulation consistently provoked a cerebrovasodilator action, preferentially in the supratentorial brain regions. In particular, 56% of the overall flow increase in the parasagittal cerebral cortex was solely attributable to the unique cerebrocortical vasodilator action of the periaqueductal gray matter, independent of unspecific effects of concomitantly occurring hypertension itself. This flow change was not associated with a specific change in the metabolic rate for O2 of this cortical region. We conclude that the major part of the unique cerebrocortical vasodilator action provoked from the defence area within the periaqueductal gray matter was mediated by non-metabolic mechanisms. The involvement of the metabolic mechanism could be of only minor importance, if any. Cerebral vasodilatation may be involved in the natural defence reactions for coping with the emergency that threatens the animal.

Anesthesia↗
PubMed1994

An improved non-radioisotopic reverse transcriptase assay and its evaluation.

We developed an improved, highly sensitive non-radioisotopic (non-RI) reverse transcriptase (RT) assay (RTA). While the original non-RI method previously reported made use of primer immobilization, our improved method was based on a primer-template immobilization procedure. We tested the template specificity, reproducibility and linearity of the new method in assays of human immunodeficiency virus type-1 (HIV-1) RT. The sensitivities of the method previously reported, the improved method and the sensitive radioisotopic (RI-) RTA were compared in assays of recombinant HIV-1 RT, partially purified HIV-1 particles, and the culture supernatant derived from HIV-1-infected cells. For each of these samples except the culture supernatant the improved method was the most sensitive. It appeared that the fetal bovine serum presented in the culture medium interfered with the assay reaction. The curve describing inhibition of the assay reaction by fetal bovine serum showed that the highest degree of sensitivity in the assay was obtained when the culture supernatant sample was diluted four times. With this degree of dilution, the sensitivity of the new method for assay of culture supernatant sample was still half that of the sensitive RI-RTA. Culture supernatants of five peripheral blood mononuclear cell samples obtained from HIV-1-seropositive carriers were assayed by both the improved method and the sensitive RI-RTA; and with each of the methods, however all virus-positive cultures could be detected. The improved non-RI RTA was considered especially useful for assay of culture supernatants for purposes of virus isolation because of its advantages of excellent sensitivity and lack of requirement for radioisotopes.

HIV Reverse Transcriptase↗
PubMed1994

The human T-cell leukemia virus type I Tax protein induces apoptosis which is blocked by the Bcl-2 protein.

The Tax protein of human T-cell leukemia virus type I activates transcription of cellular and viral genes and can immortalize primary T lymphocytes. We have previously reported that the Tax protein transforms Rat-1 cells. Here we show that Tax-transformed Rat-1 cells detach from plates to undergo apoptotic cell death by serum deprivation. These cells exhibit DNA fragmentation into oligonucleosomal fragments and chromatin condensation. Constitutive expression of a proto-oncogene, bcl-2, effectively blocks Tax-mediated apoptosis caused by serum deprivation without affecting the levels of Tax expression and the transformed phenotype of the cells.

Animals↗
PubMed1994

Creatol, a creatinine metabolite, as a useful determinant of renal function.

Analysis of creatol (CTL, 5-hydroxycreatinine), an oxidative creatinine (Cr) metabolite, in serum and urine of human subjects has indicated that CTL is a useful determinant of renal function. The existence itself of serum CTL (s-CTL) could be a diagnostic sign for chronic renal failure (CRF): in all normal subjects, s-CTL was undetectable, but s-CTL was detectable in sera of all patients with CRF (s-Cr: > 2.0 mg/dl). And the s-CTL values increased in proportion to the severity of CRF in such patients. Furthermore, the molar ratio (CTL/Cr) in both urine and serum increased significantly in proportion to the severity of CRF. Our results indicated not only hyperproduction of CTL but also higher oxygen stress in patients according to the progression of CRF. The diagnostic importance of the CTL value and the CTL/Cr ratio are discussed.

Calibration↗
PubMed1994

Autologous transplantation of the cervical sympathetic ganglion into the parkinsonian brain: case report.

The authors have reported a clinical trial of an autologous cervical sympathetic ganglion transplanted into the brain of a parkinsonian patient. A 45-year-old woman presented with bradykinesia and a gait disturbance for 8 years under L-dopa treatment. The patient underwent stereotactic transplantation of the right stellate ganglion into the right putamen. She showed marked amelioration of bradykinesia and gait disturbance 1 month after the operation, and she was able to conduct her activities of daily living without requiring L-dopa administration. The patient continued to improve gradually until 3 months after the operation. Two years after surgery, the patient functions independently as a housewife. The right hand tremor, however, became slightly worse after the operation, but it was transient. The patient developed a permanent right-sided Horner's syndrome after resection of the cervical sympathetic ganglion. Taken together with our previous data obtained from animal experiments, this case suggests that the autologous cervical sympathetic ganglion can be donor tissue for neural transplantation in Parkinson's disease.

Activities of Daily Living↗
PubMed1994

Vascularization of the pineal gland in the crow.

The blood vascularization in the pineal gland of the crow was investigated in detail using a vascular corrosion cast technique and by scanning electron microscopy. The pineal gland received two afferent arteries on either side, each artery arising from the A. cerebralis caudalis (CC) which supplied its branches to the hemisphere. The pineal gland of the crow was so highly vascularized as to be suggestive of its high metabolic and endocrine activities. The efferent veins drained into the Sinus occipitalis and the Sinus sagittalis dorsalis. There was a direct vascular connection between capillaries of the stalk of the gland and those of the Plexus choroideus.

Animals↗
PubMed1994

Pretreatment with interleukin-1 enhances survival of sympathetic ganglionic neuron grafts.

The effects of pretreatment with interleukin-1 (IL-1) on neurite growth and cell survival of rat superior cervical ganglion (SCG) explants were examined. Neonate rat SCG explants were cultured with serum-containing growth media. Pretreatment with IL-1 beta (30 U/ml) for 3 hours stimulated neurite outgrowth of the SCG explant, which was inhibited by the addition of anti-nerve growth factor (NGF) antibody to the growth medium. Adult rat autologous SCG with the same pretreatment and non-treated ganglia were transplanted into the lateral ventricle. Histological evaluation of the grafts 2 weeks after transplantation revealed that the pretreated SCG cells survived better. Pretreatment with IL-1 may achieve the NGF-mediated neurotrophic effect in sympathetic ganglionic neurons resulting in enhanced graft survival.

Animals↗
PubMed1994

Isolation of an ascitic oncodevelopmental protein exhibiting high sequence homology with calcium-binding protein MRP8.

A human oncodevelopmental protein (ODP) with a molecular size of 28 kDa was isolated, employing malignant ascitic fluid of an advanced mixed mesodermal tumor of the uterus, by anti-ODP coupled Affi-Gel 10 column chromatography, followed by preparative PAGE. The final preparation obtained with this procedure gave a single band exhibiting reactivity with an anti-ODP antibody on analytical sodium dodecyl sulfate-PAGE. The sequence of the first 20 N-terminal amino acids of this protein is identical with those of both the cystic fibrosis protein and Ca-binding protein MRP8 except at position 17, for which no result was obtained. Sequence analysis suggested that the protein shows 90% sequence homology with both these proteins.

Amino Acid Sequence↗
PubMed1994

[Transcortical sensory aphasia in a patient with metastatic brain tumor in the left frontal lobe].

We reported a case of a 62-year-old right-handed woman who had transcortical sensory aphasia caused by a metastatic brain tumor in the left frontal lobe. She had mild right hemiparesis involving the face, without hyperactive tendon reflexes. She had neither sensory disturbance nor other cranial nerve deficits. Her spontaneous speech was fluent, and she sometimes had echolalia. Her object naming, word fluency, verbal comprehension and writing were severely disturbed. This contrasted with full preservation of repetition of phonemes and short sentences. Reading of words was preserved. CT scan revealed a subcortical lesion in the left superior frontal gyrus. Gd-enhanced MRI showed a ring-enhanced mass lesion in the frontal lobe outside of Broca's area. We thereby concluded that transcortical sensory aphasia may be caused by frontal lobe lesion independent of the perisylvian speech areas.

Adenocarcinoma, Papillary↗
PubMed1994

[Dual arterial infusion chemotherapy, continuous hyperthermic peritoneal perfusion, and total parietal peritonectomy for peritoneal dissemination in gastric cancer--a case report].

A 36-year-old man developed massive ascites, of which cytology proved Class V, and upper gastrointestinal endoscopy disclosed Borrmann type 4 gastric cancer. We performed dual arterial infusion chemotherapy (DAIC) through the celiac axis and superior mesenteric artery, followed by the operation including continuous hyperthermic peritoneal perfusion, total gastrectomy, subtotal colectomy, massive intestinal resection, splenectomy, cholecystectomy, appendectomy, and total parietal peritonectomy (TPP). Ascites disappeared and the CA125 level was normalized by DAIC. This operation was well tolerated. Though the histopathological study revealed multiple peritoneal disseminations on the visceral peritoneum of stomach, small intestine, colon, and parietal peritoneum such as Douglas' pouch, there were denatured cancer cells in the visceral peritoneum to which blood supply under DAIC was distributed. These results suggested the effect of neoadjuvant DAIC and the significance of TPP.

Adult↗
PubMed1994

Projection structures of human immunodeficiency virus type 1 (HIV-1) observed with high resolution electron cryo-microscopy.

An electron microscopical study was made of human immunodeficiency virus type 1 (HIV-1) in the unstained, frozen, hydrated state at liquid helium temperature. The findings were compared with those obtained from negative staining and ultrathin sectioning. Electron cryo-microscopy confirms and extended the findings obtained by conventional methods. In particular, the virus is shown to be globular, the lipid membrane is clearly resolved as a bi-layer and the bi-layer was demonstrated to be non-uniform in width. The projections studied in the bi-layer are clearly observed to be knob-like and consist of a head, a stalk and a base.

Freezing↗
PubMed1993

Intramitochondrial protein sorting. Isolation and characterization of the yeast MSP1 gene which belongs to a novel family of putative ATPases.

Replacement of the presequence of yeast cytochrome c1 by the amino-terminal 61 residues of MAS70, a yeast mitochondrial outer membrane protein, resulted in exclusive localization of the fusion protein (termed the 61-mC1 protein) to the outer membrane. When a cytochrome c1-deficient yeast strain was transformed with a plasmid encoding the fusion protein, the cells could not grow on nonfermentable carbon sources such as glycerol. We isolated a novel yeast gene MSP1 (mitochondrial sorting of proteins) whose overexpression causes mislocalization of the 61mC1 fusion protein to the inner membrane, probably via the intermembrane space, and thereby allows the host cells to grow on glycerol. The predicted MSP1 protein (MSP1) is a hydrophilic 40-kDa polypeptide containing a putative membrane-spanning domain near the amino terminus. Further sequence analyses revealed that MSP1 is a member of a novel family of putative ATPases which share a highly conserved domain of about 185 amino acid residues, including a consensus motif for a nucleotide binding site. MSP1 was found to be an intrinsic mitochondrial outer membrane protein of an apparent molecular mass of 40 kDa with a large domain facing to the cytosol. The MSP1 gene is not essential for the cell growth either on fermentable or nonfermentable carbon sources.

Adenosine Triphosphatases↗
PubMed1993

The bcl-2 protein is inserted into the outer membrane but not into the inner membrane of rat liver mitochondria in vitro.

The bcl-2 gene encodes a 26 kDa protein, overexpression of which blocks cell apoptosis. Since conflicting data have been reported concerning the localization of the Bcl-2 protein with mitochondrial inner and outer membranes, we analyzed in vitro import of the human Bcl-2 protein into isolated rat liver mitochondria. The Bcl-2 protein translated in rabbit reticulocyte lysate was efficiently inserted into the mitochondrial outer rather than the inner membrane in a membrane potential-independent manner. The carboxyl-terminal hydrophobic stretch is essential for the Bcl-2 protein to integrate into the outer membrane. Binding of the Bcl-2 protein to the mitochondria was not affected by pretreatment of the mitochondria with trypsin, indicating that the Bcl-2 protein does not require protease-sensitive mitochondrial surface components for its membrane insertion.

Animals↗