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Biomedical subjects

R Hayashi

Publications and source records attributed to R Hayashi.

At least 235 records · Page 13Linked to original sources
PubMed1988

Conditions for thiamin assay by cyanogen bromide oxidation.

Optimum conditions for the assay of thiamin were studied using a cyanogen bromide (BrCN) oxidation method. The adopted procedure included neither pre-purification of samples through an ion exchanger nor extraction of the thiochrome into an organic solvent. The 0.25 M BrCN (the concentration before the addition of alkali) and the final NaOH concentration of approx. 1% gave the highest yield of thiochrome by a laboratory-prepared BrCN. To obtain the highest intensity of fluorescence, a concentrated BrCN (1.8 M) was introduced in place of the conventional BrCN (0.11 M), obtaining 300% or more intensity of fluorescence. For the oxidation of thiamin diphosphate, 0.15-0.2 M of laboratory-prepared BrCN gave the highest intensity of fluorescence instead of the 0.25 M for free thiamin. For simultaneous oxidation of free thiamin and thiamin diphosphate, therefore, 0.23-0.24 M of laboratory-prepared BrCN was deduced to give the best yield of fluorescence. With a solution of commercially obtained solid CNBr, optimum concentrations for the oxidation of thiamin were about 0.04 M for CNBr and about 0.16% for NaOH. When the sample contained in inhibitor of oxidation, such as ascorbic acid, the percentage of inhibition decreased inversely proportional to the concentration of the sample in a rough approximation. The degree of inhibition was not reduced by the increased amount of BrCN reagent. Thus the possibility was indicated that thiamin in an ascorbic acid-contaminated sample could be determined accurately by extrapolating values for serially diluted samples.

Ascorbic Acid↗
PubMed1988

[The role of semantic attributes of the distractor word in the script type effect on the Stroop color-word interference task].

According to Biederman and Tsao (1979), ideographic script yields more interference than phonetic script in Stroop color-naming task. They attributed this effect to the fundamental differences in the perceptual demands in reading these scripts. In order to examine this hypothesis two experiments using Kanji and Kana were conducted, in which the semantic relationship between the distractor word and the color was manipulated. It was expected that if the above hypothesis was correct the script type effect would not be influenced by the semantic attributes of distractor words. In experiment 1 using verbal response (subjects were 30 undergraduates), although the script type effect was not shown in any semantic relationship conditions, the influence of the meaning of distractor words on the interference score was observed (semantic category effect). In experiment 2 using manual response (subjects were 24 undergraduates), both the semantic category effect and the script type effect were observed, and the latter was found to vary as a function of semantic relationship between the distractor words and the colors. These results are interpreted as evidence indicating that the script type effect on Stroop interference takes place at the semantic processing level.

Adult↗
PubMed1988

Synergistic effects of combined immunosuppressive modulation. I. Unresponsiveness to dendritic cell-depleted renal allografts in dogs exposed to total-lymphoid irradiation.

Attenuation of the allogeneic stimulus provided by dendritic cells (DC) was achieved by irradiation of the donors, followed by their reconstitution with bone marrow from the prospective DLA-identical recipient. Following long-term (131-187 days) recovery free of graft-versus-host (GVH) disease, the chimeric kidneys were placed into the corresponding recipients; such allografts were rejected at 55, 55, and 60 days, respectively. Four other recipients were conditioned with 1750-1790 cgy of total lymphoid irradiation (TLI) and were then given a similar chimeric kidney from the corresponding partner. These allografts currently survive for 296, 295, 290, and 252 days, respectively. A third group of four dogs was exposed to TLI prior to transplantation of a normal DLA-identical kidney. These grafts were rejected at 20, 42, 46, and 242 days, respectively. Thirteen DLA-identical renal allografts transplanted into normal dogs survived for 13-38 days (mean survival time = 28.6 days). Depletion of allogeneic DC alone, or TLI alone, produced relative prolongations in allograft survival in canine recipients. Combined use of these two modalities, however, resulted in long-term allogeneic unresponsiveness in the recipients.

Animals↗
PubMed1988

[A case of dermatomyositis associated with breast cancer].

Presented is a case of a 48-year-old woman with dermatomyositis associated with breast cancer. A standard radical mastectomy against the breast cancer was performed in addition to the administration of adriamycin, 5-Fu, and tamoxifen as adjuvant chemoendocrine therapy. The symptoms of dermatomyositis were not that severe, so no steroid therapy was given. The patient now is ambulatory and has been discharged, and no symptoms of recurrence or exacerbations of dermatomyositis has occurred.

Adenocarcinoma↗
PubMed1987

Molecular studies on thiaminase I.

The thiaminase I gene of Bacillus thiaminolyticus was cloned on a 1.6 kb DNA fragment (enzyme molecular weight 42,000), and was expressed in both Escherichia coli and Bacillus subtilis. When a selection drug was absent, the plasmid was maintained stably for approx. 100 generations in wild-type E. coli. Instability of the thiaminase gene was demonstrated in the thiamin pyrophosphate-requiring mutant of E. coli from which the plasmid was deleted rapidly. Wild-type E. coli accumulated the enzyme in its periplasm. A method for the detection of thiaminase I enzyme in SDS-polyacrylamide gel was developed. Thiaminase I of B. thiaminolyticus was found to exist in two sizes, 44 and 42 kDa, among different strains. Moreover, thiaminase of 42 kDa became approximately 41 kDa after a long-term culture, most likely because of the action of proteinases. Thiaminase expressed in E. coli from a thiaminase-positive recombinant plasmid was 42 kDa, and showed the same mobility on SDS-polyacrylamide gele electrophoresis as the enzyme isolated from the young culture of the parent strain of B. thiaminolyticus used for cloning. This value was, therefore, considered to represent intact thiaminase that had escaped from the attack of bacilli proteinases.

Alkyl and Aryl Transferases↗
PubMed1987

Effects of ischemic nerve block on the early and late components of the stretch reflex in the human forearm.

To investigate the peripheral afferent mechanisms which mediate the short latency (M1) and long latency (M2) components of the stretch reflex, we have recorded EMG responses to extension perturbations at the wrist before and following inflation of a blood pressure cuff around the upper arm. After approximately 30 min of ischemia, the reflexes had almost completely disappeared, although subjects were still able to activate the forearm muscles voluntarily. As the ischemic block developed, the M2 component began to decrease in amplitude sooner than M1, and up to the time of complete loss of reflex activity, the suppression of M2 was relatively greater than that of M1. These results suggest that M2 may be mediated by a population of afferent fibers different from the Ia afferents which are believed to generate the M1 response.

Adult↗
PubMed1987

Nucleoside-triphosphatase and hydrolysis of thiamin triphosphate in Escherichia coli.

A membrane-bound nonspecific triphosphatase of E. coli was solubilized and purified to a homogeneous SDS-acrylamide gel electrophoresis band. It was found to be a single polypeptide of 16 kDa requiring no Mg2+, with an optimal pH at 6.5. The substrate specificity was broad and a nonspecific Mg2+-independent ribonucleoside-triphosphatase (NTPase) activity was expressed together with thiamin-triphosphatase activity. The molecular size and characteristics were clearly different from the known NTPase (EC 3.6.1.15). Using the purified thiamin-triphosphatase II, ATP:thiamin-diphosphate phosphoryl transferase (EC 2.7.4.15) activity was demonstrated with an optimal pH of approx. 5.3. Considering its kinetic parameters and other characteristics, however, the thiamin triphosphate synthesizing activity was not thought to take part in cellular thiamin triphosphate synthesis. The possibility that thiamin-triphosphatase II plays a part in the hydrolysis of thiamin triphosphate to control its cellular level is suggested.

Cell Membrane↗
PubMed1987

Modulation of reflex and voluntary EMG activity in wrist flexors by stimulation of digital nerves in hemiplegic humans.

Changes in EMG activity in the wrist flexor muscles were studied in response to electrical stimulation of digital nerves and to sudden extension perturbations at the wrist produced by a torque motor in human subjects with unilateral cerebral hemisphere lesions. With the subjects maintaining a steady voluntary contraction against a constant load, digital nerve stimulation produced a series of excitatory and inhibitory changes in tonic EMG activity from the wrist flexors in both the normal and paretic arm. The most consistent response was a period of EMG inhibition beginning approximately 38 msec after the stimulus and lasting approximately 35 msec. With relatively weak electrical stimuli, there was less EMG inhibition in the paretic arm than in the normal arm; with stronger stimuli, the inhibitory response was similar in the two arms. The electrical stimuli and mechanical perturbations were then delivered together, with the interval between them adjusted so that the expected period of inhibition following electrical stimulation coincided with either the early (M1) or the long latency (M2) components of the stretch reflex. In the normal arm electrical stimulation produced more inhibition of the M2 component than of the M1 component. In the paretic arm, inhibition during the M2 component was less marked and similar in degree to that which occurred during M1. These results are compatible with the view that M1 and M2 are normally mediated by separate neural pathways. The long latency EMG activity evoked by muscle stretch in the paretic arm of hemiplegic patients may be generated by pathways or mechanisms different from those in the intact arm.

Electric Stimulation↗
PubMed1987

Preoperative preparation of high-risk, specifically hyperimmunized canine renal allograft recipients with total-lymphoid irradiation and cyclosporine.

Hyperimmunized subjects are a particularly high-risk and rapidly growing group in the patient population awaiting renal transplantation. In a search for methods designed to ameliorate the prognosis in such cases, dogs of defined DLA genotype were sensitized with DLA incompatible skin allografts and injections of buffy coat. Each recipient was challenged with a renal allograft bearing the same DLA incompatibilities. Five dogs received kidney transplants, without any other treatment, and rejected their transplants at 2.5, 4, 5, 6, and 6.5 days, respectively. Another four dogs were given a 9-11-week course (1760 +/- 35 cGy) of total-lymphoid irradiation (TLI), followed by rabbit antithymocyte globulin (ATG); these animals rejected their renal allografts at 7, 8, 14, and 17 days, respectively. Five other dogs were treated with TLI and received cyclosporine (CsA) and methylprednisolone (MPd) daily until graft rejection. Their renal allografts survived for 7.5, 8.5, 20, 62, and 227 days, respectively. Renal allografts placed in normal recipients under the same conditions of donor-recipient DLA incompatibility had a mean survival time of 12.4 days (range: 10-18 days). At the time of transplantation, the specific anti-DLA antibody titers in the recipients were 81 to 243 in the untreated dogs; 27 to 81 in the TLI-ATG-treated group, and 3 to 243 in the TLI-CsA/MPd-treated group. The titers fell within 24-48 hr after renal transplantation, to 3 to 81 in the untreated sensitized dogs; they were 3 to 9 in the TLI-ATG-treated group, and were 9 to 243 in the TLI-CsA/MPd treated group. The cytotoxic antibody titers reached postoperative peaks of 6500 to 200,000 in the untreated dogs; 729 to 6500 in the TLI-ATG-treated dogs, and 243 to 6500 in the TLI-CsA/MPd-treated recipients. The combined use of TLI and CsA/MPd can significantly inhibit the capacity of immunized recipients to muster a secondary humoral response to the DLA antigen(s) used in the sensitization process; such treatment also abrogates the ability of the recipients to reject renal allografts bearing the same DLA specificities in accelerated fashion. This effect of TLI and cyclosporine may be of relevance to current severe problems in high-risk hyperimmunized human renal transplant candidates.

Animals↗
PubMed1987

Effect of cutaneous nerve stimulation on voluntary and stretch reflex electromyographic activity in wrist flexors in humans.

1. Changes in electromyographic (e.m.g.) activity in the wrist flexors of normal human subjects were studied in response to electrical stimulation of digital nerves and to sudden extension perturbations at the wrist produced by a torque motor. 2. With the subjects maintaining a steady voluntary contraction, stimulation of the digital nerves produced a series of excitatory and inhibitory changes in the tonic e.m.g. activity from the wrist flexors. The most prominent and consistent response was a period of e.m.g. inhibition beginning 39 ms after the stimulus and lasting for approximately 36 ms. 3. The stretch reflex evoked by extension perturbations of the wrist consisted of an early response (M1) with an onset latency of approximately 30 ms, and a late response (M2) with an onset latency of approximately 60 ms. 4. The electrical stimuli and the mechanical perturbations were then delivered together, varying the interval between them so that the period of inhibition resulting from the electrical stimuli occurred at the same time as the M1 or M2 components of the stretch reflex, or during the later voluntary response. 5. The amount of e.m.g. inhibition during the M2 component was significantly greater than that during M1 (P less than 0.02). This result is compatible with the view that M1 and M2 are mediated by separate neural pathways.

Adult↗
PubMed1987

LDL-apheresis; potential procedure for prevention and regression of atheromatous vascular lesion.

Nine patients with familial hypercholesterolemia (FH), 6 with homozygotes and 3 with heterozygotes, were treated with long term repetitive LDL-apheresis. The techniques are simple plasma exchange with human albumin solution, double membrane filtration, and selective LDL-adsorption by dextran sulfate-cellulose gel. The average term was 3.5 years except for the two homozygotes for whom the treatment was only initiated in our facility. Plasma total cholesterol levels were controlled between pretreating level, 320 to 500 mg/dl, and posttreating level, 100 to 160 mg/dl, by biweekly treatments. All patients showed remarkable improvement of cutaneous and tendinous xanthomas. One homozygous patient died at 31 years old of myocardial infarction after 2 years of treatment. A homozygous patient who has been treated since 5 years old for 6 years was reexamined by angiography and was shown to have atheromatous lesions regressed in the aortic valve region and in the left renal artery.

Arteriosclerosis↗
PubMed1987

Serum cholesterol level in normal people: association of serum cholesterol level with age and relative body weight.

Serum cholesterol level was studied in normal subjects in Kasakake Village. The serum cholesterol levels increased significantly with age, from the third to the fifth decade in males and from the third to the seventh decade in females. Thereafter, the levels were maintained in males while declined in females. The mean peak values (+/- SD) were 178 +/- 31 mg/100 ml in males and 207 +/- 37 mg/100 ml in females. The presumptive values of the zero-year-old obtained from the regression lines calculated from the plot of serum cholesterol values against age were 129 mg/100 ml and 112 mg/100 ml in males and females respectively. Throughout the age-range examined in females, the serum cholesterol level was well correlated with the relative body weight determined with modified Broca's method. A similar, but less obvious correlation was demonstrated in males. However, there was not comparable change in the relative body weight against the trend of the serum cholesterol level in both sexes. In the babies normally delivered with full term, the mean cholesterol level (+/- SD) in the umbilical cord blood serum was 65 +/- 13 mg/100 ml and it increased to 150 +/- 46 mg/100 ml during one to three months after birth which was very close to the presumptive values obtained from the regression lines in the adults. There also was significant correlation between the cholesterol value and the body weight. It is concluded that in normal people, age and relative body weight are major and independent determinants of serum cholesterol level from the start of their life.

Aged↗
PubMed1987

Hydrolysis and synthesis of thiamin triphosphate in bacteria.

Thiamin triphosphate (ThTP) in early stationary phase cells of Escherichia coli grown in nutrient broth with 0.1% yeast extract was found to constitute approximately 5-7% of cellular thiamin diphosphate (ThDP) or around 5 nmol/g cell. Nearly the same level of ThTP was obtained in a Bacillus strain. When E. coli was loaded with an excess of ThTP or ThDP, cellular ThTP was found to be controlled in the course of the long term to maintain its ratio to the amount of cellular ThDP. The ThTP vs. ThDP ratio in E. coli cells after short-term ThDP uptake was found to be a function of the cellular growth phase. The ratio in early exponential phase E. coli cells was found to be approximately 4% and it became lower (less than 3%) when cell growth proceeded to the late exponential stage. Two phosphatases specific for ThTP (ThTPase) among thiamin phosphates were detected in E. coli. One required Mg2+ and was found mainly in the soluble fraction, while the other was Mg2+-independent and originated from the membrane. The two ThTPases were similar to their rat tissue counterparts.

Bacillus↗