Biomedical subjects

A Okada

Publications and source records attributed to A Okada.

At least 253 records · Page 14Linked to original sources

PubMed1995

[Effect of topical timolol on the blood velocity of the iris microcirculation and the aqueous veins in human subjects].

To clarify the effect of topical timolol on the microcirculation in human eyes, the blood velocity changes of the iris microcirculation and the aqueous veins were measured before and 90 minutes after instillation of timolol in 8 eyes of 8 healthy volunteers by laser speckle flowgraphy. Systemic blood pressure, heart rate and intraocular pressure were measured before and 90 minutes after the instillation. The fellow eyes were measured as controls. The blood velocity decreased in the iris microcirculation (10% decrease, p < .05) and in the aqueous veins (8% decrease, p < .02) 90 minutes after instillation of timolol. The diameter of the aqueous veins did not change, so that the blood flow in the aqueous veins decreased (6% decrease, p < .02) after instillation. The intraocular pressure and pulse rate decreased (20 and 8% decrease, p < .002 and < .001, respectively) 90 minutes after the instillation. The blood velocity, vessel diameter, and intraocular pressure of fellow eyes and systemic blood pressure showed no significant change. These findings indicate that topical instillation of timolol induces decrease of blood flow in the iris, and, possibly, in the ciliary body. The instillation of timolol may decrease aqueous humor formation, and blood flow in aqueous veins.

Administration, Topical↗

PubMed1995

Involvement of endothelin in peripheral circulatory change induced by hand-arm vibration.

Physiologic mechanisms involving local vasoregulating factor, endothelium-derived relaxing factor (EDRF) and endothelium-derived constricting factors (EDCF) have been postulated to play a role in VWF. Recent evidence that endothelin is a potent vasoconstrictor peptide indicates that it may play a role in vasoregulation during vibration exposure through the local actions of EDRF or EDCF. Therefore, we examined the effects of grasping (50 N) and hand-arm vibration with an unweighted acceleration of 50 m/s2 rms at a frequency of 120 Hz in the direction of X-axis on digital blood flow (DBF) and on the level of plasma endothelin in 7 healthy male office workers. DBF was measured by an apparatus based on the thermal diffusion method where the thermal diffusion flow probe was incorporated in the Peltier's stack. In the grasping test, DBF decreased by about 40% from resting level within 1 minute after the grasping was begun, and was maintained at almost the same level during grasping, but increased immediately after cessation of grasping. In the vibration exposure test, initial decrease in DBF due to grasping was the same as that observed in the grasping test, but DBF gradually increased when exposure to vibration was performed simultaneously. No significant change in plasma endothelin level was induced by grasping. Endothelin was significantly lower after exposure to vibration than at rest and after grasping. The grasping-induced decrease in DBF seemed to be due to mechanical compression of the vessels. The negative correlation between DBF and endothelin during vibration exposure suggests that a reduction in release of endothelin from smooth muscle into the vessel cavity during vibration leads to vasodilatation, possibly attributable to the local axon reflex.

Blood Flow Velocity↗

PubMed1994

Development of the human medial superior olivary nucleus: a morphometric study.

The development of the human medial superior olivary nucleus was studied in serial sections of 10 fetuses at 12-35 weeks of gestation (WG), an infant at 2 months of age and an adult of 63 years using an electronic planimeter with a computer. Morphometric analysis suggested that the development of the human medial superior olivary nucleus accelerates between 16 and 21 WG in terms of columnar lengths and volumes, neuronal sizes and circularity ratios, while it matures gradually in terms of the amount of Nissl bodies.

Female↗

PubMed1994

Cloning of the cDNA encoding rat tissue inhibitor of metalloproteinase 1 (TIMP-1), amino acid comparison with other TIMPs, and gene expression in rat tissues.

We have cloned the cDNA encoding the rat tissue inhibitor of metalloproteinase 1 (TIMP-1) from a cDNA library derived from healing skin wounds. The deduced amino acid (aa) sequence shows 66, 35 and 34% identity with human TIMP-1 and TIMP-2, and chicken TIMP-3 aa sequences, respectively. High-level expression of rat TIMP-1 RNA was detected in the skin wounds and in normal ovary.

Amino Acid Sequence↗

PubMed1994

Vesicle-bound conformation of melittin: transferred nuclear Overhauser enhancement analysis in the presence of perdeuterated phosphatidylcholine vesicles.

We determined a detailed conformation of the honeybee venom peptide melittin when bound to phosphatidylcholine vesicles using proton NMR. In the presence of vesicles of perdeuterated dipalmitoylglycerophosphocholine, two-dimensional transferred nuclear Overhauser enhancement (TRNOE) experiments were carried out. By a distance geometry calculation using NOE-derived distance constraints followed by a simulated annealing refinement, the N-terminal (Leu6-Leu10) and C-terminal (Leu13-Lys21) parts were found to have an alpha-helical conformation, whereas five C-terminal residues (Arg22-Gln26) did not show a unique conformation in the vesicle-bound state. The two alpha-helices were connected via a less structured segment (Thr11-Gly12) with a helix bend angle of 86 degrees +/- 34 degrees. Model distance geometry calculations using distance constraints extracted from a tetrameric melittin molecule in crystal assured us that the NOE constraints can accurately reproduce melittin's structure, as well as helping to interpret the NMR structures. Although the vesicle-bound conformation of melittin is similar to that occurring in a methanol solution and in dodecylphosphocholine micelles, significant differences were found in the conformation of C-terminal basic residues and the helix bend angle. This is the first study to clearly demonstrate conformation differences in micelle- and vesicle-bound peptides. In addition, lytic activity of melittin and its analogs showed better correlation with a peptide conformation in vesicles than in either methanol or micelles.

Amino Acid Sequence↗

PubMed1994

Differential activation of transcription versus recombination of transgenic T cell receptor beta variable region gene segments in B and T lineage cells.

We have tested the ability of the T cell receptor beta (TCR-beta) transcriptional enhancer (E beta) to confer transcriptional activation and tissue-specific V(D)J recombination of TCR-beta V, D, and J segments in a transgenic minilocus recombination substrate. We find that the minimal E beta element, as previously shown for a DNA segment that contained the E mu element, promotes a high level of substrate D to J beta rearrangement in both B and T cells, but only promotes V beta to DJ beta rearrangement in T cells. Thus, both the E mu and E beta elements similarly direct V(D)J recombination of this substrate in vivo, supporting a general role for transcriptional enhancers in the normal regulation of this rearrangement process. Surprisingly, however, we found that both the V beta and DJ beta portion of the constructs were transcribed in an enhancer-dependent fashion (conferred by either E mu or E beta) in both B and T lineage cells, including normal precursor B cells propagated in culture. These findings indicate that, at least in some contexts, transcriptional activation, per se, is not sufficient to confer V(D)J recombinational accessibility to a substrate V gene segment.

Animals↗

PubMed1994

Low frequency of the p53 gene mutations in neuroblastoma.

BACKGROUND: The p53 gene frequently is affected by point mutations, rearrangements, or deletions that contribute to the genesis or progression of a wide variety of human adult solid tumors; however, to the authors' knowledge, this gene alteration has not been analyzed in neuroblastoma. METHODS: Genomic DNA samples from 20 children with neuroblastoma, including 16 patients with advanced disease, were screened for the presence of mutations in exons 5-9 of the p53 gene, where over 90% of mutations have been reported to be located in human cancer. The screening technique employed polymerase chain reaction/single-strand conformation polymorphism analysis followed by direct DNA sequencing. RESULTS: Heterozygous mutations were detected in 2 of the 20 cases. A silent mutation (T to G transversion) at codon 172 and a missense mutation (G to T transversion) at codon 259 were found in patients with Stage II and Stage IV disease, respectively. Thus, p53 mutations were found to occur in neuroblastoma, but at a low frequency (2 of 20). CONCLUSIONS: Our data suggest that in a minority of neuroblastomas, p53 gene mutations may play a contributing role in tumorigenesis, but other genes presumably play a major role in this tumor.

Child↗

PubMed1994

Mechanisms that control antigen receptor variable region gene assembly.

The somatic assembly of antigen receptor genes--known as V(D)J recombination--is a highly regulated process at several different levels. V(D)J rearrangement is limited to stages of early B and T cell development by the lymphoid specific expression of recombinase activity. A common recombinase is apparently responsible for the rearrangement of all antigen receptor loci. Thus, the tissue specific and ordered rearrangement of each antigen receptor locus must depend on controlling their 'accessibility' to the recombinase. Here, we outline recent work that has contributed to the current understanding of mechanisms that control V(D)J rearrangement.

Alleles↗

PubMed1994

Changes of cerebral vasoactive intestinal polypeptide- and somatostatin-like immunoreactivity induced by noise and whole-body vibration in the rat.

To clarify the role of vasoactive intestinal polypeptide (VIP) and somatostatin, somatotropin-release inhibiting factor, (SRIF) neurons in the response to organisms to noise or whole-body vibration stress, VIP- and SRIF-like immunoreactivity were determined in various regions of the rat brain following exposure for 90 min to noise (broad band, 102 dB) or whole-body vibration (20 Hz, 4.0 g). Both noise and whole-body vibration significantly increased VIP-like immunoreactivity in the amygdala. A significant reduction of VIP-like immunoreactivity in the hippocampus was induced only by whole-body vibration. On the other hand, SRIF-like immunoreactivity was decreased significantly in the hypothalamus and increased significantly in the amygdala by noise and whole-body vibration, respectively. The present findings would seem to indicate that the amygdalofugal VIP neural system is involved in regulating hypothalamic and pituitary hormone secretions in non-specific reactions to stress. Responses of hippocampal VIP and the amygdalofugal SRIF to whole-body vibration stress are assumed to be activated as specific reactions to the stress.

Animals↗

PubMed1994

The effect of donor-specific transfusion and cyclosporin A on small bowel transplantation in the rat.

Pre-transplant blood transfusions are given as a means of desensitization to reduce the required dose of cyclosporin A (CsA). In this study, the effect of pretransplant blood transfusion on host survival and T-cell function against alloantigen were investigated. Male Lewis rats (RT1(1)) were used as the recipients in all experiments, and male DA rats (RT1a) were used as the blood and small bowel donors, and as a source of allogeneic stimulator cells. Male BUF rats (RT1b) were used as donors of third party blood, and of allo-stimulator cells in a delayed-type hypersensitivity (DTH) response. In our experimental design, Lewis rats were divided into the following groups according to the type of administration: (1) a donor-specific blood transfusion (DST) 8 days preoperatively and a concurrent 5-day course of CsA at 10 mg/kg per day; (2) a nonspecific third party blood transfusion (NST) and CsA at 10 mg/kg per day from day 8 to day 4 preoperatively; (3) CsA alone from day 8 to day 4 preoperatively; (4) DST alone 8 days preoperatively; or (5) no treatment, being the control group. Postoperative treatment consisted of CsA at 2.5 mg/kg per day for 30 days. Rats conditioned with NST plus CsA, CsA alone, DST alone, and the untreated control rats survived for 7.2 +/- 1.2, 9.0 +/- 2.2, 6.8 +/- 0.4, and 7.4 +/- 1.6 days, respectively. In contrast, the five rats conditioned with DST plus CsA survived for 100 days or more.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Effect of amino acids in total parenteral nutrition on cholestasis in newborn rabbits.

The effect of amino acids on total parenteral nutrition (TPN)-associated cholestasis was examined using a newborn rabbit TPN model. Twenty-nine newborn Japanese white rabbits were divided into four groups. Group I received a TPN solution with composition and total energy similar to that of rabbit breast milk. Group II received more dextrose than group I. Group III received a larger amount of amino acids than group II. Group IV was nourished by lactating mothers. After 7 days of TPN, blood samples and liver specimens were obtained. In group II, the serum total bilirubin level (1.44 +/- 0.68 mg/dL) was significantly higher than normal (0.28 +/- 0.07 mg/dL) and that of group I (0.49 +/- 0.12 mg/dL). In group II, histological cholestasis was present, characterized by bile plugs in bile ducts, bile pigments in Kupffer cells and hepatocytes, and nonprotein calorie overload changes in clear cell transformation of the hepatocytes. In group III, the serum total bilirubin level (0.23 +/- 0.05 mg/dL) was normal, and there were minimal cholestatic and nonprotein calorie overload changes (histologically) in the liver. These results indicate that cholestasis in this study was induced by nonprotein calorie overload and was prevented by an appropriate volume of amino acids.

Amino Acids↗

PubMed1994

DNA flow cytometric analysis of neuroblastoma: distinction of tetraploidy subset.

Neuroblastoma has several characteristics that differentiate it from other adult malignancies. The ploidy pattern of neuroblastoma has been shown to be related to prognosis. Specifically, a DNA diploidy pattern is associated with a poorer outcome, and an aneuploidy pattern is associated with a better outcome. A tetraploidy pattern has also been identified; however, there is little information regarding this pattern. To examine the properties of neuroblastoma according to these DNA ploidy patterns, the authors performed flow cytometric analysis (retrospectively) for 61 neuroblastoma cases, using paraffin-embedded tissues. Fifty-six of the cases had analyzable results. Calculated DNA indices (DI) ranged from 1.0 to 2.30. The 56 cases were divided into three groups according to DI: diploid (DI = 1.0 to 1.17, n = 19), aneuploid (DI = 1.25 to 1.75, n = 26), and tetraploid (DI = 1.81 to 2.30, n = 11) groups. Compared with the aneuploid group, the diploid group had a stronger correlation with older patient age (> or = 1 year) (P < .01), more advanced clinical stage (III, IV) (P < .01), and poorer prognosis (P < .001). The tetraploid group had properties that were statistically similar to those of the diploid group (P < .05, P < .05, P < .001, respectively). These findings indicate that a subset of DNA tetraploid is present in neuroblastoma, and this subset, which may have clinical and biological characteristics similar to those of the DNA diploid group, should be distinguished from DNA aneuploidy.

Aneuploidy↗

PubMed1994

Antenatal diagnosis of sacrococcygeal teratoma with hydrops fetalis; a case report.

Fetal sacrococcygeal teratoma (SCT) with hydrops fetalis is known to have a poor prognosis. We report a case of SCT with hydrops fetalis which was diagnosed antenatally at 30 weeks gestation. After delivery by cesarean section, the tumor was removed and the infant is alive one year after surgery with no sign of recurrence. However, he has profound brain damage, perhaps caused by hypoxia secondary to the perinatal hypovolemia. This case demonstrates that a 30 weeks' gestation, survival is possible in fetal cases of SCT with hydrops fetalis, and illustrates the importance of perinatal circulatory management.

Adult↗

PubMed1994

Serum creatinine level in predicting the development of hypertension. Ten-year follow-up of Japanese adults in a rural community.

In a 10-year prospective study, we investigated the utility of the serum creatinine level in predicting the development of hypertension in Japanese adults, all of whom lived in a rural community. The study included 229 subjects, 91 men and 138 women aged 30 to 69 years, who were normotensive (systolic blood pressure 140 mm Hg or less and diastolic blood pressure 90 mm Hg or less) and had no prior history of antihypertensive treatment at baseline (1979 to 1980). Hypertension was defined as systolic blood pressure more than 140 mm Hg and diastolic blood pressure more than 90 mm Hg and starting antihypertensive medication. Stepwise proportional hazard analysis selected serum creatinine (P < .001) as an independent, significant predictor of hypertension together with systolic blood pressure (P < .001), age at entry (P < .001), body mass index (P = .008), and diastolic blood pressure (P = .011). The age- and sex-adjusted relative risk for subjects with a serum creatinine level of 1.2 mg/dL or higher compared with those with a level less than 1.1 mg/dL was 0.42 (95% confidence interval, 0.25 to 0.71). The mechanism of this association might relate to muscle mass and physical exercise or, possibly, to a primary renal abnormality. It appeared that the serum creatinine level may be useful in predicting future hypertension.

Adult↗

PubMed1994

Splenectomy for treatment of immunoblastic lymphadenopathy.

A 5-month-old girl was diagnosed with immunoblastic lymphadenopathy (IBL) on the basis of clinical symptoms and pathological findings. alpha-interferon, immunosuppressive agents such as cyclosporin A, deoxyspagarine, and azathioprine, and an alternating regimen of low-dose 6-mercaptopurine, cyclophosphamide and methotrexate were tried with partial success. Finally, splenectomy was carried out at 58 months of age, inducing prolonged complete remission without any medication.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1994

Effects of respiratory interval on vagal modulation of heart rate.

To determine whether paced breathing (PB) and respiratory interval of PB modify the relationship between spectral components of heart rate variability (HRV) and cardiac vagal tone, we studied seven healthy young males under the condition of beta-adrenergic blockade by intravenous propranolol (0.2 mg/kg). Compared with spontaneous breathing, PB at the same respiratory interval as that of individual spontaneous breathing showed no significant effect on the amplitude of the high-frequency (HF) component or the mean R-R interval in either the supine or tilt position, whereas the PB decreased the amplitude of the low-frequency (LF; 0.04-0.15 Hz) component in both positions (P = 0.004 and 0.042, respectively). When the respiratory interval was increased from 3 to 6 s, the HF amplitude showed a progressive increase in both positions (P = 0.001 and 0.035, respectively), while the LF amplitude and mean R-R interval remained unchanged. These results indicate that the effects of PB and respiratory interval on the spectral components of HRV are not mediated by the changes in mean cardiac vagal tone and support the hypothesis that increased respiratory interval amplifies the respiratory-related vagal modulation of heart rate.

Adrenergic beta-Antagonists↗

PubMed1994

Assessment of frequency shifts in R-R interval variability and respiration with complex demodulation.

A complex demodulation (CDM) method for continuous assessment of frequency shifts and time-dependent changes in amplitude in the rhythmic components existing in predefined frequency bands was proposed and applied to the analysis of high-frequency (HF) and low-frequency (LF) components of the R-R interval and to the analysis of respiration via impedance spirogram. Simulation studies revealed that this CDM technique furnishes mathematical features well suited to the investigation of non-stationary R-R interval signals and can delineate time-dependent fluctuations in both amplitude and frequency, accurately differentiating between HF and LF components. Analysis of data during paced breathing at different respiratory frequencies revealed that the estimated frequency of the HF component and respiration faithfully reflected the frequency of paced breathing. Analysis of data during dynamic exercise with increasing workload (20 W/min) showed that the frequency of the HF component was elevated with exercise and that both HF and LF amplitudes were reduced progressively with advancing load. CDM-derived frequency and amplitude of respiration were highly correlated to direct breath-by-breath respiratory frequency and tidal volume measurements. We conclude that this method could provide a powerful means for continuously assessing time-dependent changes in both cardiovascular and respiratory variations.

Adult↗

PubMed1994

Amyloid beta protein precursor with Kunitz-type protease inhibitor domains (APPI) in cerebrospinal fluid and APPI mRNAs in cultured skin fibroblasts of patients with Alzheimer's disease.

We studied amyloid beta protein precursor with Kunitz-type protease inhibitor domains (APPI) concentration in cerebrospinal fluid (CSF) and APPI mRNA in skin fibroblast in Alzheimer's disease (AD). The subjects consisted of AD, cerebrovascular dementia (VD) and age-matched controls. We measured the APPI concentration in the CSF by the trypsin antibody sandwich ELISA. APPI mRNA was examined by the RT-PCR technique. The CSF APPI concentration in AD was significantly higher than that of VD and controls. The CSF APPI concentration in AD was high in the initial stage of dementia and decreased during the course. The expression of APPI mRNA in skin fibroblasts in AD was also significantly higher than that of VD and controls. These results suggest that measurements of APPI levels in CSF and APPI mRNA in skin fibroblasts may be useful for early diagnosis of AD.

Aged↗