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Biomedical subjects

A Masuda

Publications and source records attributed to A Masuda.

At least 127 records · Page 7Linked to original sources
PubMed1996

Open reduction of chronic lunate and perilunate dislocations.

Four patients with chronic lunate and perilunate dislocations were treated by open reduction and internal fixation. The interval between injury and operation was 7, 8, 14 and 18 weeks, respectively. Both palmar and dorsal surgical approaches were needed to reduce the old dislocation in all cases. A case of dorsal trans-scaphoid perilunate dislocation showed concurrent partial disruption of the scapholunate ligament. Transient vascular compromise of either the lunate or the proximal scaphoid fragment was noted in three patients. Despite the delay in treatment, all patients had satisfactory outcomes.

Adult↗
PubMed1996

Changes in taste responsiveness in patients with anorexia nervosa during behavior therapy.

We evaluated the changes in taste responsiveness of anorexia nervosa (AN) patients during behavior therapy. Taste responsiveness of AN patients was lower at admission when compared to controls but it improved significantly over the course of treatment (p < 0.01). Taste responsiveness improved prior to increase in body weight. No significant correlation was noted between weight gain and improvement in taste responsiveness. The period required to reach a food intake of 1600 Kcal/day and the duration of hospitalization were highly correlated (r = 0.72, p < 0.05). Those who reached 1600 Kcal/day earlier showed more rapid improvements in taste responsiveness. These results suggest that decreased taste responsiveness in AN patients can rapidly improve and such early improvement may result in better progression of treatment.

Adolescent↗
PubMed1996

Functional bovine immunoglobulins in Boophilus microplus hemolymph.

The aim of the present work was to quantify the passage of bovine immunoglobulins into the hemolymph of the tick Boophilus microplus during the feeding process and to determine their antibody activity. The knowledge is of paramount importance when vector control or blocking of disease transmission is attempted by vaccination of cattle. Approximately 2% of bovine immunoglobulin present in the serum as determined by competitive ELISA was demonstrated in hemolymph of B. microplus and antibody activity against an antigen of B. microplus in the hemolymph of ticks fed on bovine immunized with the antigen purified from tick eggs was detected by Western blot assay. The antibody reactivity detected against the B. microplus antigen showed that functional antibodies are present in the hemolymph of fully engorged ticks for at least 48 h after completing the parasitic life cycle.

Animals↗
PubMed1996

Differentiation of classical swine fever virus from ruminant pestiviruses by reverse transcription and polymerase chain reaction (RT-PCR).

A reverse transcriptase-polymerase chain reaction (RT-PCR) assay was designed to allow the differentiation of pestiviruses by the expected size of the amplified fragments. One oligonucleotide primer, conserved amongst pestiviruses, and two others specific for either classical swine fever virus (CSFV) or bovine viral diarrhea virus (BVDV), were designed from the 5' non-coding region of the genome. CSFV infected cultures (10 strains) amplified a fragment of an expected size of 200 bp; BVDV cultures (23 strains) or border disease virus (BDV) (2 strains) amplified a fragment of an expected size of 260 bp. The specificity of the amplified fragments was confirmed by restriction enzyme analysis. The threshold of sensitivity was 100 TCID50 for CSFV and 1 TCID50 for BVDV. The RT-PCR described here provides a rapid and sensitive diagnostic tool for the detection and differentiation of CSFV from ruminant pestiviruses.

Animals↗
PubMed1996

Decreased bone mineral density associated with early menopause progresses for at least ten years: cross-sectional comparisons between early and normal menopausal women.

To establish whether early onset of menopause carries an increased risk of osteoporosis, we compared the bone mineral density (BMD) of the second to fourth lumbar vertebrae (L2-4) between 18 women who had menopause before 43 years of age (early menopause group) and 19 women who had menopause after reaching 43 years of age (normal menopause group). Serum levels of calcium, phosphorus, calcitonin, intact parathyroid hormone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2), and alkaline phosphatase activity were measured, and urine samples were analyzed to derive calcium/creatinine, hydroxyproline/creatinine, pyridinoline/creatinine, and deoxypyridinoline/creatinine (D-Pyr/Cr) ratios. Mean BMD was significantly lower in the early menopause group than in the normal menopause group, and individual BMD values in about half of the subjects in the former group were below the fracture threshold for Japanese women. Serum concentrations of LH, FSH, and E2 were slightly, but not significantly, lower in the early menopause group than in the normal menopause group. The D-Pyr/Cr ratio was significantly higher in the early menopause group than in the normal menopause group. There was no correlation between L2-4 BMD and age or the number of years after menopause in the normal menopause group, but both age and the number of years after menopause were negatively correlated with L2-4 BMD in the early menopause group. These results indicate that BMD in women who have early menopause continues to decline for up to 10 years, and that menopause and aging increase the risk of osteoporosis.

Adult↗
PubMed1996

Maturation of human cortical auditory function: differences between normal-hearing children and children with cochlear implants.

OBJECTIVE: We investigated maturation of cortical auditory function in normal-hearing children and in children who receive stimulation of their auditory system through a cochlear implant. DESIGN: As a measure of cortical auditory function, auditory evoked responses (AERs) were recorded from normal-hearing children and adults as well as from children and adults fitted with a cochlear implant. Morphological and latency changes for evoked responses recorded at electrode Cz are reported. RESULTS: For normal-hearing children, there is a gradual evolution of AER features that extends through adolescence, with P1 latency becoming adult-like in the late teens. Latency changes for P1 occur at the same rate for implanted children, but the overall maturation sequence is delayed. By extrapolation from the existing data, the age at which P1 latency becomes adult-like is delayed by approximately 5 yr for the implanted population. Other typical features of the AER, namely N1 and P2, are either delayed in developing or absent in the implanted children. CONCLUSIONS: These preliminary findings suggest both similarities and differences in cortical auditory maturation for normal-hearing and implanted children. For implanted children, the 5 yr delay for maturation of P1 latency roughly corresponds to the average 4.5 yr interval between the onset of deafness and the time of implantation. These findings suggest that during the period of deafness, maturation of cortical auditory function does not progress. However, some, if not all, maturational processes resume after stimulation is reintroduced.

Adult↗
PubMed1996

Effects of hyperinsulinaemia on renal function and the pressor system in insulin-resistant obese adolescents.

1. In the present study, using the euglycaemic hyperinsulinaemic glucose clamp technique, we investigated the effects of hyperinsulinaemia on sodium-water metabolism and the pressor system in obesity, both of which have been reported to be closely associated with insulin resistance and/or hyperinsulinaemia. 2. Sixteen obese young subjects and 24 non-obese young subjects who were all normotensives, participated in this study. The 2 h euglycaemic hyperinsulinaemic glucose clamp was performed in a fasting state. The mean glucose infusion rate needed to maintain a fasting blood sugar level (FBS) during the last 30 min of the clamp was used as an indicator of insulin sensitivity (M-value). Before and after the clamp, the following parameters were measured: creatinine clearance (Ccr); urinary excretion of sodium (UNaV); fractional excretion of sodium (FENa); plasma renin activity (PRA); plasma aldosterone concentration (PAC) and plasma noradrenaline concentration (PNA). 3. The M-value was significantly lower in obese subjects compared with non-obese subjects, although FBS and fasting immunoreactive insulin levels were similar in both groups. UNaV and FENa fell only in obese subjects during the clamp, while Ccr showed no significant change in either group. PNA and PRA increased significantly and PAC tended to increase in both groups. 4. These results suggest that obese subjects have insulin resistance with respect to glucose metabolism, but that urinary sodium excretion and the pressor system remain insulin-sensitive; the sensitivity of the sodium retaining action to hyperinsulinaemia was actually higher in obese subjects than in non-obese subjects. Therefore, if compensatory endogenous hyperinsulinaemia was raised by insulin resistance, these two factors may lead to chronic sodium retention and pressor system stimulation and, in turn, to hypertension in obesity.

Adolescent↗
PubMed1996

Retinal melatonin is not involved in corneal mitotic rhythms in the Japanese quail: effects of formoguanamine hydrochloride and eye-lid suture.

Relation between retinal melatonin and corneal mitotic rhythms in the Japanese quail was investigated in experiments manipulating the ocular physiology by treatments with formoguanamine hydrochloride (FG) and eye-lid suture. In experiment 1, we investigated the effects of FG, which is known to induce photoreceptor degeneration, on retinal melatonin and corneal mitotic rhythms. FG-treatment completely abolished the retinal melatonin rhythms in both LD 12:12 and constant darkness (DD), but the corneal mitotic rhythm was maintained with high mitotic rate in darkness under a LD cycle and subjective night under DD. The result suggests that 1) the photoreceptor cells in the retina are the site for melatonin production and/or for the oscillator which drives the circadian rhythm in retinal melatonin, and 2) melatonin is not involved in generation of the corneal mitotic rhythm. In experiment 2, we investigated the effects of eye-lid suture, which is known to induce eye enlargement and bulgy cornea, on the retinal melatonin and corneal mitotic rhythms. Eye-lid suture abolished the corneal mitotic rhythm in both LD and DD, with a high mitotic rate being maintained throughout 24 hr. But retinal melatonin maintained its rhythm with high levels in darkness under a LD cycle and in subjective night under DD. The result suggests that 1) bulgy cornea in the sutured eye was induced by the increase in mitotic rate in the light period, and 2) disappearance of the corneal mitotic rhythm does not have a relation to retinal melatonin. These results suggest that retinal melatonin is not involved in generation of the corneal mitotic rhythm and that there are two circadian clock systems in the eye.

Animals↗
PubMed1996

Variable effects of click polarity on auditory brain-stem response latencies: analyses of narrow-band ABRs suggest possible explanations.

The auditory brain-stem responses (ABRs) to rarefaction and condensation clicks were obtained for 12 normal-hearing subjects in quiet, and high-pass masking at 8, 4, 2, 1, and 0.5 kHz. Derived narrow-band wave V latency differences were analyzed with respect to (1) stimulus polarity, (2) absolute differences irrespective of polarity. The analyses revealed no significant stimulus polarity effects on latency for the derived bands. Absolute latency differences regardless of polarity tended to be greater for those derived bands having lower characteristic frequencies (CFs). However, these differences were smaller than the expected half-period of the theoretical CF. Further analyses in three additional subjects using repeated runs of the same polarity indicate that this increase in absolute latency difference with lower derived band CF does not reflect a simple half-period change owing to polarity, but rather to the increase variability in measuring the peak latency of the lower CF derived bands. The variability is consistent with variability of eighth nerve PST histograms behavior observed in animal work [Kiang et al., "Discharge patterns of single fibers in the cat's auditory nerve," Research Monograph No. 35 (MIT, Cambridge, MA, 1965)]. Thus claimed polarity effects observed in other ABR work using absolute values may have been affected by this variability. It appears from these current data that half-period latency shifts of wave V owing to stimulus polarity differences are not observed in derived bands responses initiated from frequency specific regions of the cochlea.

Adolescent↗
PubMed1996

Effect of prior O2 breathing on ventilatory response to sustained isocapnic hypoxia in adult humans.

Sixteen healthy volunteers breathed 100% O2 or room air for 10 min in random order, then their ventilatory response to sustained normocapnic hypoxia (80% arterial O2 saturation, as measured with a pulse oximeter) was studied for 20 min. In addition, to detect agents possibly responsible for the respiratory changes, blood plasma of 10 of the 16 subjects was chemically analyzed. 1) Preliminary O2 breathing uniformly and substantially augmented hypoxic ventilatory responses. 2) However, the profile of ventilatory response in terms of relative magnitude, i.e., biphasic hypoxic ventilatory depression, remained nearly unchanged. 3) Augmented ventilatory increment by prior O2 breathing was significantly correlated with increment in the plasma glutamine level. We conclude that preliminary O2 administration enhances hypoxic ventilatory response without affecting the biphasic response pattern and speculate that the excitatory amino acid neurotransmitter glutamate, possibly derived from augmented glutamine, may, at least in part, play a role in this ventilatory enhancement.

Administration, Inhalation↗
PubMed1996

Contribution of peripheral chemoreceptor drive in exercise hyperpnea in humans.

The peripheral chemoreceptors play a dominant role in the respiratory compensation of lactic acidosis during heavy exercise of humans. Our object was to determine the contribution of peripheral chemoreceptors to exercise hyperpnea during mild to moderate and heavy exercise above the anaerobic threshold. We used a hyperoxic suppression test in six normal male subjects. Inspired gas was abruptly changed without the subject's knowledge from air to pure oxygen for 5 to 6 breaths. The maximal ventilatory depression after O2 breathing was 5.5 +/- 1.7 L/min (BTPS) at mild exercise, and the depression increased with increasing exercise intensity up to 12.8 +/- 4.1 L/min (BTPS). The relative contribution of the peripheral chemoreceptors to ventilation in terms of percentage of the maximal ventilatory depression was maintained, being 20% throughout the entire work ranges studied. The contribution of the peripheral chemoreceptors to total ventilation is hardly altered by lactic acidosis caused by heavy exercise above the anaerobic threshold according to our data. These results suggested that the peripheral chemoreceptors may not be solely responsible for excessive hyperventilation, or residual activities of peripheral chemoreceptors still exist after O2 breathing especially during heavy exercise above the anaerobic threshold.

Acidosis, Lactic↗
PubMed1996

Structural determination of stevastelins, novel depsipeptides from Penicillium sp.

Structures of novel immunosuppressants, stevastelin A, B and B3(1) were determined by their spectroscopic and chemical studies. Three stevastelins were shown to be cyclic depsipeptides composed of a fatty acid and three amino acid moieties. The sequence of these moieties was determined to be as 3,5-dihydroxy-2,4-dimethylstearylvalylthreonyl (or O-sulfonylthreonyl in stevastelin A)-O-acetylserine. Cyclic structures were shown to be formed by ester linkages between the carboxylic group of the O-acetylserine moiety and the 5-hydroxy group of the fatty acid moiety in stevastelin A and B, and the 3-hydroxy group of the fatty acid moiety in stevastelin B3.

Anti-Bacterial Agents↗
PubMed1996

Absolute structural determination of stevastelin B.

Stevastelin B, obtained from a culture of a Penicillium sp. NK374186, is a novel depsipeptide containing three amino acids and 3,5-dihydroxy-2,4-dimethylstearic acid. The stereochemistry of the three amino acids was determined by HPLC analysis, and the relative configuration of the 3,5-dihydroxy-2,4-dimethylstearic acid was elucidated by chemical conversion and NMR analysis. The absolute stereochemistry of stevastelin B was determined by synthetic methods.

Anti-Bacterial Agents↗
PubMed1996

[A case of cystic hemangioblastoma of the medulla oblongata].

Cystic hemangioblastoma of the brain stem is an extremely rare clinical entity. Only eight cases have been reported in the literature. This is a report of a case of successful extirpation of a cystic hemangioblastoma of the medulla oblongata. A 47-year-old man was admitted to our clinic with the complaint of progressive numbness on his left upper limb since January 1995. Neurological examination revealed numbness and decreased vibration sensation on his left upper limb. MRI showed a cystic 1.5 x 2.0 cm lesion on the medulla oblongata, and with administration of Gd-DTPA, a small mass lesion on the dorsolateral side of the medulla oblongata. Left vertebral angiogram revealed a tumor fed directly from the left vertebral artery. An operation was performed using a suboccipital approach. The dorsal surface of the medulla was swollen edematously, suggesting the site of a cyst, which emptied by means of opening the wall. The reddish tumor was embedded on the left dorsolateral surface of the medulla oblongate. A total extirpation of the tumor was carried out under microscopic procedure. Histologically, the tumor was diagnosed as a hemangioblastoma. The patient was free from his distressing numbness immediately after the operation, and discharged without neurological deficit.

Brain Neoplasms↗