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Biomedical subjects

H Hayashi

Publications and source records attributed to H Hayashi.

At least 739 records · Page 41Linked to original sources
PubMed1995

Hypoaminotransferasemia in patients undergoing long-term hemodialysis: clinical and biochemical appraisal.

BACKGROUND & AIMS: It has been reported that patients with chronic renal failure have low serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels as a result of vitamin B6 deficiency. Chronic hepatitis C is common among patients undergoing hemodialysis, and low aminotransferase levels cause diagnostic problems. The aim of this study was to determine the cause of hypoaminotransferasemia. METHODS: Serum levels of vitamin B6 and its coenzyme were reassessed in relation to AST and ALT levels in patients undergoing long-term hemodialysis using high-performance liquid chromatography. RESULTS: The mean (+/- SD) serum AST and ALT levels in 304 patients negative for hepatitis B surface antigen and anti-hepatitis C virus were 9.2 +/- 2.4 and 7.4 +/- 1.7 IU/L, respectively. In 556 normal adults, they were 22.7 +/- 5.4 and 18.0 +/- 4.0 IU/L, respectively (P < 0.001). Mean serum vitamin B6 and pyridoxal-5'-phosphate levels in patients undergoing dialysis were not reduced compared with the control, although occasionally patients had low levels. The AST and ALT assay reagents in Japan do not contain added pyridoxal-5'-phosphate; addition of pyridoxal-5'-phosphate (0.1 mmol/L) to the reagent significantly increased measurements to similar extents in both groups. CONCLUSIONS: Serum AST and ALT levels in patients undergoing dialysis are very low, but they are not a result of vitamin B6 deficiency. The upper normal limits of AST and ALT levels in patients undergoing dialysis should be reduced considerably, and these levels should be interpreted with caution in the diagnosis of liver disease.

Adult↗
PubMed1995

Altered motor cortical excitability to magnetic stimulation in a patient with a lesion in globus pallidus.

A 27-year-old man with Behçet's disease presented with dyskinesia of the right hand and leg, but without paresis. MRI showed a discrete lesion in the internal segment of the left globus pallidus. SPECT (single photon emission tomography) disclosed increased perfusion in the hand and leg area of the left motor cortex and ipsilateral thalamus compared to that of the corresponding regions on the right. The dyskinesia was considered to be produced by disinhibition of the motor cortex due to loss of inhibitory inputs from the ipsilateral pallidum via the thalamus. Double transcranial magnetic stimulation revealed loss of suppression (loss of intracortical inhibition) of the left motor cortex while it showed normal suppression on the right, even though conventional techniques of magnetic stimulation failed to show any changes in excitability of the left motor cortex. We conclude that it is possible to detect changes of motor cortical excitability caused by dysfunction of some inputs from the basal ganglia by using the double cortical stimulation technique here described.

Adult↗
PubMed1995

Decrease of medullary catecholaminergic neurons in multiple system atrophy and Parkinson's disease and their preservation in amyotrophic lateral sclerosis.

We investigated the number of tyrosine hydroxylase (TH)-immunoreactive neurons in the C1 and A2 regions of the medulla, the sites of the baroreflex arc, in 7 patients with multiple system atrophy (MSA), 8 with Parkinson's disease (PD), 9 with amyotrophic lateral sclerosis (ALS), and 12 age-matched normal subjects to analyze the relationship between cardiovascular dysfunction and medullary catecholaminergic neurons. Orthostatic hypotension (OH) was marked in all the MSA patients and moderate in three PD patients. Three of the five ALS patients who had been on respirators showed lability of blood pressure; paroxysmal hypertension and nocturnal hypotension without compensatory tachycardia. All the MSA patients showed extremely marked decrease of TH-immunoreactive neurons in both the C1 and A2 regions. In the patients with Parkinson's disease, numerous TH-immunoreactive neurons contained Lewy bodies that were immunostained by antibody to TH. TH-immunoreactive neurons were decreased very markedly in the A2 regions of two patients with OH, and three patients without OH showed fairly marked decreases in the C1 or A2 region. In contrast, the number of TH-immunoreactive neurons in ALS was the same as in normal subjects. In MSA and some PD patients, orthostatic hypotension may partly be due to the involvement of the medullary catecholaminergic neurons. The lability of blood pressure in ALS probably is not related to the medullary catecholaminergic neurons.

Aged↗
PubMed1995

Serum aminotransferase levels as an indicator of the effectiveness of venesection for chronic hepatitis C.

BACKGROUND/AIMS: Iron cytotoxicity may play an important role in chronic hepatitis C. The effects of venesection suggest that a slight iron overload contributes to hepatic injury in subjects infected with hepatitis C virus. A better indication of the efficacy of venesection was studied in patients with and without overt iron overloading. METHODS: All 40 patients had chronic hepatitis C but none had hemochromatosis of a known etiology. A serum ferritin level of 10 ng/ml or less was chosen as the treatment goal. A mean blood volume of 2400 +/- 1100 ml was removed during treatments lasting 5 +/- 3 months. RESULTS: Treatment significantly reduced the mean serum levels of alanine aminotransferase activity from 128 +/- 74 to 63 +/- 28 IU/l (p < 0.01). The baseline enzyme activity was highly correlated with reduction in activity after treatment (r = 0.94, p < 0.01), but the baseline levels of ferritin and histochemistry for iron showed poor correlations with the reduction in enzyme activity (r = 0.63 with p < 0.01 and r = 0.38 with p < 0.05, respectively). CONCLUSIONS: Thus, serum levels of aminotransferases were a more important indicator for venesection than conventional indices of iron overload, probably because cytotoxic iron includes some reactive iron species rather than stored iron alone.

Adult↗
PubMed1995

Mode of hepatitis C infection not associated with blood transfusion among chronic hemodialysis patients.

In a retrospective study carried out on about 730 patients with chronic renal failure who underwent ambulatory hemodialysis from January 1991 to June 1994, 49 patients were found to have developed acute hepatitis C, as confirmed by seroconversion for anti-HCV antibodies without blood transfusion in the preceding 6-month period. Epidemiological survey disclosed that two patients undergoing dialysis at consoles separated by one console developed acute hepatitis C in October 1992, and another three patients at adjacent consoles also developed acute hepatitis C within 2 weeks in April/May, 1993. It was found that some negligent nurses could have withdrawn needles from these patients one after another without changing gloves at the termination of the dialysis procedure. After reeducation of the staff members and introduction of a new type of adhesive pad to be placed on the needle wounds at the time of needle withdrawal, no new case of acute hepatitis C occurred for more than 1 year, suggesting nosocomial spread of HCV infection among hemodialysis patients in a mode that is preventable with very strict aseptic precautions.

Adult↗
PubMed1995

QRST time integral values in 12-lead electrocardiograms before and after radiofrequency catheter ablation in patients with Wolff-Parkinson-White syndrome.

OBJECTIVES: We investigated the usefulness of QRST values obtained from 12-lead electrocardiograms (ECGs) for identification of repolarization abnormalities before and after radiofrequency ablation in patients with Wolff-Parkinson-White syndrome. BACKGROUND: Marked T wave abnormalities often appear after ablation and have been attributed to a continuation of repolarization abnormalities present before ablation (cardiac memory). However, to our knowledge repolarization properties before and after ablation have not been assessed quantitatively. METHODS: We calculated the ECG QRST values from 53 patients with Wolff-Parkinson-White syndrome and compared these values before, immediately after and 1 day and 1 week after successful ablation in 25 patients. RESULTS: QRST values were abnormally high in lead V1 in 7 of 28 patients with a left-sided accessory pathway and abnormally low in leads III and aVF and high in lead aVL in 12, 9 and 10 of 20 patients, respectively, with a right-sided accessory pathway. Preexisting QRST abnormalities were still present immediately and 1 day after ablation but were usually absent by 1 week after ablation. QRST values before, immediately after and 1 day after ablation were not significantly different in any lead. In 14 patients with ablation of a left-sided accessory pathway, QRST values before, immediately after and 1 day after ablation in lead V1 and immediately after ablation in leads I, aVR and V2 were significantly different from QRST values in those leads 1 week after ablation. In six patients with ablation of a right-sided accessory pathway, QRST values before, immediately after and 1 day after ablation in leads III, aVL and aVF and immediately after ablation in lead II were significantly different from QRST values in those leads 1 week after ablation. CONCLUSIONS: Electrocardiographic QRST values may provide useful quantitative information with respect to repolarization properties before and after ablation in patients with Wolff-Parkinson-White syndrome that is otherwise difficult to obtain by conventional ECG analysis.

Adult↗
PubMed1995

Left ventricular dimensions and autonomic balance during head-up tilt differ between patients with isoproterenol-dependent and isoproterenol-independent neurally mediated syncope.

OBJECTIVES: This study sought to elucidate differences in mechanisms of neurally mediated syncope between patients with syncope induced by head-up tilt alone and those requiring isoproterenol infusion to induce syncope during head-up tilt. BACKGROUND: Some patients with neurally mediated syncope require isoproterenol to induce syncope during head-up tilt (isoproterenol dependent), and others do not (isoproterenol independent). Differences in mechanisms between these two groups have not been well elucidated. METHODS: A 60 degrees head-up tilt test was performed in 13 patients with isoproterenol-independent syncope (Group I, mean [+/- SD] age 28 +/- 12 years), 14 patients with isoproterenol-dependent syncope (Group II, mean age 34 +/- 14 years) and 20 control subjects without syncope (Group III, mean age 32 +/- 12 years). Left ventricular size and contractility were determined by echocardiography, and sympathovagal balance was determined with power spectral analysis of heart rate variability using a maximal entropy method. RESULTS: Group I patients had smaller left ventricular dimensions than Group II and III during baseline tilt. During head-up tilt with isoproterenol infusion (0.01 to 0.04 microgram/kg body weight per min), left ventricular dimensions decreased to the same extent in Groups II and III, but fractional shortening was greater in Group II than in Group III at the end of the tilt. The ratio of low (0.05 to 0.15 Hz) to high frequency (0.15 to 1.0 Hz) component became greater in Group I than in Groups II and III during the last period of baseline tilt. However, the ratio was greater in Group II than in Group III during the last period of the tilt with isoproterenol. CONCLUSIONS: Patients with isoproterenol-independent syncope had an exaggerated decrease in left ventricular size and sympathetic predominance preceding syncope during head-up tilt. In contrast, in patients with isoproterenol-dependent syncope, similar changes in autonomic nervous balance were evident only during isoproterenol infusion in addition to head-up tilt.

Adolescent↗
PubMed1995

Long-term follow up of visual acuity in eyes with stage 5 retinopathy of prematurity after closed vitrectomy.

PURPOSE: This study was done to determine the efficacy of closed vitrectomy on long-term visual acuity of stage 5 retinopathy of prematurity. METHODS: We studied the visual acuity of eyes that had undergone retinal reattachment by closed vitrectomy for stage 5 retinopathy of prematurity and were followed up for more than three years. RESULTS: Forty-nine eyes of 31 patients among a total of 71 eyes of 48 consecutive patients were operated on and followed up for more than three years. Retinal reattachment occurred in 29 (59%) of the 49 eyes. Six patients (eight eyes) did not respond to visual acuity testing because of mental retardation or cerebral palsy. Measured visual acuity in the remaining 21 eyes varied from no light perception in one eye, light perception in four eyes, Recognizable hand movement in three eyes, 20/2,000 to 20/200 in seven eyes, 20/200 to 20/25 in five eyes, and 20/25 in one eye. No correlation was seen between visual outcome and factors such as gestational age, birth weight, and configuration of retinal detachment. Markedly better visual acuity was obtained in eyes that underwent initial surgery within four months of birth. CONCLUSIONS: Useful vision can be obtained after reattachment of the retina by closed vitrectomy on some patients who have stage 5 retinopathy of prematurity. Better visual acuity may be obtained by earlier surgery.

Birth Weight↗
PubMed1995

Comparison of casual blood pressure and twenty-four-hour ambulatory blood pressure in high school students.

OBJECTIVE: To perform ambulatory blood pressure monitoring (ABPM) in high school students and to compare the 24-hour values with casual blood pressure (BP). METHODS: Ambulatory BP monitoring was carried out in 190 high school students, 15 or 16 years of age, with elevated casual BP during the first examination at school for hypertension; 66 had elevated casual BP at both the first and the second examinations (group H1), and 124 students were normotensive at the second examination (group H2). Sixty-two students who were consistently normotensive served as control subjects (group N). Average BPs for the 24-hour period, the awake period (10 AM to 10 PM), and the sleeping period (1 AM to 6 AM) were calculated. RESULTS: Average BP for each period was significantly higher in group H1 than in group N. Average BP in group H2 for these periods was intermediate between those of group H1 and of group N. The casual BP had a significant positive correlation with the average BP during the awake period (r = 0.55, p < 0.01 for systolic BP; r = 0.37, p < 0.01 for diastolic BP). In most subjects the casual BP readings were higher than BP during ABPM. CONCLUSIONS: Casual BP measurements correlated with 24-hour BP, but they tended to be higher than the measurements obtained during 24-hour ABPM.

Adolescent↗
PubMed1995

The correlation between incision size and corneal shape changes in sutureless cataract surgery.

PURPOSE: To examine the correlation between incision size and corneal shape changes in sutureless surgery using corneal topography. METHODS: Two hundred eyes undergoing sutureless cataract surgery were assigned randomly to three groups according to the incision size: group A, 3.2-mm incision; group B, 4.0-mm incision; and group C, 5.0-mm incision. All eyes were examined by corneal topography preoperatively as well as at 1 week and at 1, 3, and 6 months after surgery. RESULTS: In the average of difference maps of eyes in the 3.2-mm incision group, a wound-related flattening in the peripheral cornea occurred 1 week after surgery, but decreased rapidly thereafter. Subsequently, no significant changes were observed in the cornea after 1 month. In the 4.0-mm incision group, with a reduction of the wound-related peripheral flattening, an irregular steepening appeared in the lower central cornea 6 months after surgery. In the 5.0-mm incision group, a similar steepening in the lower cornea occurred just after surgery. This steepening persisted and even extended to the upper central cornea in its later postoperative periods. CONCLUSION: The 3.2-mm incision hardly produced any irreversible corneal shape changes, whereas both the 4.0- and 5.0-mm incisions caused a persistent irregular steepening in the central cornea.

Adult↗
PubMed1995

Physicochemical characterization of parenteral lipid emulsion: influence of cosurfactants on flocculation and coalescence.

PURPOSE: The stability of lipid emulsions (LE) containing various cosurfactants (oleic acid, cholesterol, Tween 80, or HCO-60) was evaluated using the maximum total interaction energy, Vtmax and the energy barrier for coalescence, W. METHODS: The Vtmax and W were calculated from the zeta potential and the rate of increase in LE particle size, respectively. RESULTS: The Vtmax and W of LE containing the oleic acid were 0.598 x 10(-19) J and 3.03 x 10(-19) J, respectively, while those of LE without the cosurfactant were 0.141 x 10(-19) J and 1.36 x 10(-19) J. CONCLUSIONS: These findings suggest that oleic acid prevents the flocculation and coalescence of LE. The Vtmax and W of LE containing the cholesterol were 0.435 x 10(-19) J and 0.63 x 10(-19) J, respectively, suggesting that the cholesterol prevents the flocculation of LE but does not affect the coalescence. Analysis of the stability of LE was performed by the separate considerations of the flocculation and coalescence.

Castor Oil↗
PubMed1995

Physicochemical characterization of parenteral lipid emulsion: determination of Hamaker constants and activation energy of coalescence.

The particle size of lipid emulsion (LE) is changed by flocculation and coalescence. This change in particle size was studied using values obtained for maximum total interaction energy (Vtmax) for flocculation and activation energy for coalescence (E). Vtmax was calculated using DLVO theory, and E was calculated from the rate of increase in particle size in LE. Two LEs (PC99LE and PC70LE) were prepared from lecithins containing 99% and 70% phosphatidylcholine, respectively. The Hamaker constants for PC99LE and PC70LE were found to be 1.4 x 10(-22) J and 3.1 x 10(-21) J, respectively. Vtmax for PC99LE was 4.7 kT at 121 degrees C, and E was 1.5 x 10(-19) J, while Vtmax for PC70LE at 121 degrees C was 151 kT and E was 3.2 x 10(-19) J. These findings suggest that PC99LE readily underwent flocculation and coalescence with increase in particle size, but that the particle size of PC70LE changed little. The degrees of flocculation and coalescence of LE were determined separately using values of Vtmax and E. These parameters are thus quite useful in predicting the stability of LE.

Calcium Compounds↗
PubMed1995

Remodeling mechanisms of transseptal fibers during and after tooth movement.

The remodeling mechanisms of transseptal fibers during and after tooth movement were investigated histologically. An autoradiographic study was conducted to assess the synthetic response. One hundred fifty male Wistar strain growing rats were divided into three groups--one control and two experimental groups. Animals in the experimental groups were subjected to tooth movement with 25 g and 150 g of force. Maxillary first and second molars were separated and retained mechanically. Transseptal fibers were stretched in proportion to the amount of force applied for up to 2 days. Dynamic remodeling with proliferation of fibroblasts during tooth movement and slow rearrangement during retention periods occurred in both experimental groups. Collagen phagocytosis within the fibroblasts was observed ultrastructurally during the experimental periods. The number of silver grains in fibroblasts in the collagen fibers increased 160% the first day and 206% during the first 3 days. Proliferating fibroblasts remodeled the transseptal fibers through the synthesization and degradation of collagen fibers.

Alveolar Process↗
PubMed1995

Spatial, temporal and hormonal regulation of programmed muscle cell death during metamorphosis of the frog Xenopus laevis.

No examination to date has been made of apoptosis during vertebrate muscle development. The authors recently reported programmed muscle cell death to be important in tail degeneration as well as in the larval-to-adult conversion of the dorsal body muscles of Xenopus laevis during metamorphosis [30]. In the present study, we examined programmed cell death (PCD) of the dorsal body and tail muscle morphologically and biochemically, with special attention to whether apoptotic processes, such as chromatin fragmentation and apoptotic body-formation actually occur, and whether triiodothyronine (T3) induces such processes. Light microscopic observation indicated muscle fibers break down into short fragments (sarcolytes or muscle apoptotic bodies) during the metamorphic climax, not only in tail but also in larval-type fibers of dorsal body muscles. Apoptotic bodies first appeared near the base of the tail in early climax (stage 59) when the T3 level is quite high, and thereafter expanded in an anterior direction in the dorsal body and posteriorly in the tail. The ratio of apoptotic area to total muscle area became maximum (10%-30% in dorsal body muscles and 50% in the tail) at the climax (stages 63-64). During these stages, genomic DNA fragmented into oligonucleosome-sized units (200 bp, 400 bp, 600 bp ...) in both body and tail muscles. To confirm whether this chromatin fragmentation is associated with apoptotic bodies, in situ DNA nick end labeling (TUNEL) was applied to sections of the dorsal body and tail muscles. Labeled muscle nuclei could be found only in muscle apoptotic bodies but not in intact muscle fibers, indicating DNA fragmentation was associated with cell fragmentation during metamorphosis. It thus follows that morphological (apoptotic body formation) and biochemical (fragmentation of chromatin) processes occurring during PCD of dorsal body and tail muscles are identical. To determine whether T3 regulates programmed muscle cell death, the effects of T3 on DNA ladder formation were examined in tails cultured in vitro. The oligonucleosomal DNA ladder was found to form only in tails incubated with T3, thus showing T3 to induce programmed muscle cell death without interaction with other endocrine organs during metamorphosis.

Animals↗
PubMed1995

Type I and type II interferons upregulate functional type I interleukin-1 receptor in a human fibroblast cell line TIG-1.

The regulation of type I interleukin-1 receptor (IL-1R) expression by type I, interferon (IFN)-alpha A/D, and type II IFN, IFN-gamma, in a human fibroblast cell line TIG-1 was investigated. After 2 h stimulation with human IFN-alpha A/D or IFN-gamma, the levels of type I IL-1R mRNA increased. We previously reported that IL-1 upregulates transcription and cell surface molecules of type I IL-1R in TIG-1 cells through induction of prostaglandin (PG) E2 and cAMP accumulation. However, indomethacin was unable to inhibit the effect of IFNs, indicating that IFNs augment IL-1R expression through a pathway distinct from that of IL-1. The augmentation was also observed in other fibroblast cell lines. Nuclear run-on assays and studies of the stability of mRNA suggested that the increase in IL-1R mRNA was a result of the enhanced transcription of IL-1R gene. Binding studies using 125I-IL-1 alpha revealed that the number of cell surface IL-1R increased with no change in binding affinity by treatment with these IFNs. Pretreatment of the cells with IFNs enhanced IL-1-induced IL-6 production, indicating that IFNs upregulate functional IL-1R. IL-1 and IFNs are produced by the same cell types, as well as by the adjacent different cell types, and are concomitantly present in lesions of immune and inflammatory reactions. These results therefore suggest that IFNs exhibit synergistic effects with IL-1 through upregulation of IL-1R. Augmented production of IL-6 may also contribute to the reactions.

Cell Line↗
PubMed1995

Glycosylated human recombinant interleukin-1 alpha, neo interleukin-1 alpha, with D-mannose dimer exhibits selective activities in vivo.

To investigate the effect of carbohydrate-introduction on IL-1 activity, especially in vivo, and to develop IL-1 with less deleterious effects, recombinant human IL-1 alpha was coupled with mannose dimer, alpha-D-Man-1-6-D-Man [Man2 alpha(1-6)] by an acyl azide method. Previous studies demonstrated that the glycosylated IL-1 exhibited reduced activities compared with original IL-1 in all the experiments performed in vitro. In this study, we investigated the in vivo activities of Man2 alpha(1-6)-conjugated IL-1 alpha. The glycosylated IL-1 alpha exhibited very low pyrogenic activity and alpha 1-acid glycoprotein induction compared with untreated IL-1 alpha. Untreated IL-1 alpha increased the serum level of IL-6, but the glycosylated IL-1 alpha did not. However, the glycosylated IL-1 alpha possessed the same potency as untreated IL-1 alpha in reduction of serum levels of glucose and triglyceride and in recovery of peripheral white blood cells in 5-fluorouracil-treated mice. Therefore, glycosylation of IL-1 appeared to be useful for the development of neoIL-1 with selective activity in vivo.

Animals↗
PubMed1995

Pyridoxal enzymes: mechanistic diversity and uniformity.

Pyridoxal 5'-phosphate (PLP) acts as the coenzyme in a vast number of reactions in amino acid metabolism. The study of PLP enzymes is one of the most fascinating frontiers in enzymology, and now the mechanism s of several types of PLP enzymes are being discussed at the atomic level based on crystallographic, spectroscopic, and site-directed mutagenesis studies. In this review, I summarize the important findings, including those provided by classical studies, on the reaction mechanisms of several PLP enzymes, with the intention of discussing the chemically and thermodynamically consistent principle of the catalytic action of PLP enzymes common to all the enzymes of this group, and the uniqueness of individual enzymes that endows them substrate and reaction specificity.

Catalysis↗