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Biomedical subjects

K Honda

Publications and source records attributed to K Honda.

At least 505 records · Page 28Linked to original sources
PubMed1990

Substrate-dependent shift of optimum pH in porcine pancreatic alpha-amylase-catalyzed reactions.

Porcine pancreatic alpha-amylase (EC 3.2.1.1, abbreviated as PPA) hydrolyzes alpha-D-(1,4) glucosidic bonds in starch and amylose at random, and the optimum pH for the substrates is 6.9. The optimum pH, however, shifted to 5.2 for the hydrolytic reaction of low molecular weight oligosaccharide substrates such as p-nitrophenyl alpha-D-maltoside, gamma-cyclodextrin, maltotetaitol, and maltopentaitol. The optimum pH for the oligosaccharides consisting of more than five glucose residues, such as maltopentaose and maltohexaitol, was 6.9. From the analysis of the hydrolysates, it was clear that the shift of the optimum pH occurred only when the fifth subsite of PPA in the productive binding modes was occupied by a glucosyl residue of the substrates. The value of Km was independent of pH between 4 and 10 but that of kcat was dependent on pH. The pH profiles of kcat for the above substrates did not fit a simple bell-shaped curve predicted by a two-catalytic-group mechanism. Instead, they were well analyzed theoretically by three pK values and two intrinsic kcat values. Enthalpy changes for the three pK's (4.90, 5.35, and 8.55 at 30 degrees C) were determined from the temperature dependence of pH profiles for maltopentaitol and maltohexaitol to be 0.0, 2.87, and 7.33 kcal/mol, respectively. These results indicate that productive binding modes of the substrates directly affect the catalytic function of the enzyme. From the present thermodynamic analysis and reported three dimensional structure at the active site of PPA [Buisson, G. (1987) EMBO J. 6, 3909-3916], one can assume that a histidyl residue (101, 201, or 299) acts as a proton donor and two carboxyl groups (Asp 197, Glu 233, or Asp 300) act as proton donors or acceptors, and the productive binding mode covering the fifth subsite changes configurations between the catalytic residues and the glucosidic bond hydrolyzed and modulates kinetic parameters depending on pH.

Amylose↗
PubMed1990

Effects of medial preoptic area lesions on sleep and wakefulness in unrestrained rats.

Bilateral radiofrequency lesions of the medial preoptic area (MPOA) in unrestrained male rats resulted in a significant decrease in slow wave sleep (SWS) in the light period throughout two postoperative weeks, although the night-active pattern of circadian rhythms was little affected. Both diurnal and nocturnal paradoxical sleep (PS) gradually increased after the lesions. Within one week, however, the daily amount of total sleep (SWS + PS) was recovered to the normal level, since the loss of diurnal SWS was compensated by an increase in nocturnal sleep at the expense of wakefulness. The MPOA lesions brought about a transient elevation of brain temperature, which lasted only for the diurnal period of the day of lesioning. It is speculated that the MPOA plays a definite role in the passage of sleep-regulatory information, especially concerning the circadian distribution of sleep.

Animals↗
PubMed1990

Electrophysiological evidence for neural connections between the supraoptic nuclei.

Effects of electrical stimulation of the contralateral supraoptic nucleus (SON) on the activity of neurosecretory neurons in the SON were studied in urethane-anesthetized lactating rats. Thirty-one out of 41 oxytocin neurons were excited and only two neurons were inhibited by contralateral SON stimulation. Eight out of 26 vasopressin neurons were excited and 8 were inhibited. These responses were not affected by suckling stimuli. Neither oxytocin nor vasopressin neurons tested were antidromically activated by contralateral SON stimulation. Thus monosynaptic connections between the bilateral SON neurosecretory neurons seem to be very few, if any. These results suggest that neural connections exist between the bilateral SON and that they are mainly polysynaptic.

Action Potentials↗
PubMed1990

Chronic intake of panax ginseng extract stabilizes sleep and wakefulness in food-deprived rats.

The amount of wakefulness and slow wave sleep significantly fluctuated during 48 h food deprivation and subsequent recovery periods in freely behaving male rats. In contrast, such fluctuations were significantly less prominent in age-matched male rats chronically treated with Panax ginseng extract via drinking water. It is speculated that the ginseng extract may exert a stabilizing effect on sleep-waking disturbances which possibly accounts for its outstanding health-improving activities.

Animals↗
PubMed1990

Elevated frequency of a specific allele of the L-myc gene in male patients with bone and soft-tissue sarcomas.

Restriction fragment length polymorphisms (RFLPs) of 2 oncogenes, c-Ha-ras and L-myc, have been analyzed in 101 patients with bone and soft-tissue sarcoma and in 98 normal individuals. The c-Ha-ras gene was highly polymorphic both in sarcoma patients and in normal individuals. In contrast to our previous observation in breast cancer patients (Honda et al., 1988), no significant difference in allele frequencies between normal and sarcoma populations was observed. The L-myc locus revealed 2-allele polymorphism, allele L (10-kb) and S (6.6-kb), after digestion with Eco RI. The allele frequencies of L and S in sarcoma patients were 0.381 and 0.619, respectively, and those in normal individuals were 0.485 and 0.515, respectively. While the distributions of alleles in both populations fitted well with the Hardy-Weinberg equilibrium, the frequency of the S allele was significantly higher in sarcoma patients than in normal individuals (p less than 0.05). When sarcoma patients were divided into male and female subpopulations, this difference was highly significant only in males (p less than 0.01) but not in females. Our results suggest that males carrying the S allele may be prone to develop sarcoma.

Alleles↗
PubMed1990

Panax ginseng extract modulates sleep in unrestrained rats.

The amount of wakefulness and slow wave sleep (SWS) during the 12-h light period slightly but significantly decreased and increased, respectively, in freely behaving rats after continued 1-week intake of Panax ginseng extract through drinking water (15 mg/day). Paradoxical sleep was little affected. No sleep parameters were modulated by the treatment during the dark period. The diurnal SWS enhancement disappeared and recovered to the baseline level after 2 weeks of continued treatment. It is speculated that the well known health-improving effect of the ginseng may be, at least in part, related to an enhancement of sleep.

Animals↗
PubMed1990

Lead poisoning in swans in Japan.

We investigated the occurrence, source and exposure time of lead poisoning in whooper swans (Cygnus cygnus cygnus) and Bewick's swans (Cygnus columbianus bewickii) in Japan during the winters of 1984-1987. Concentrations of lead in various tissues and physiological evidence of lead shot in some birds indicated that lead shotgun pellets were the source of lead, and exposure occurred after the birds arrived in Japan. Mortality probably occurred within 30 days after exposure to, and retention of, lead shot in the gizzard.

Journal Article↗
PubMed1990

Characterization of myxoid substance of human aortic sarcoma.

An autopsy case of aortic sarcoma which was located in the intima of the abdominal aorta and characterized by abundant extracellular myxoid substances was examined. Histological, immunohistochemical and ultrastructural studies revealed no characteristics suggestive of endothelial, leiomyogenic or histiocytic differentiation. Histochemical and biochemical analyses revealed that the myxoid substances were glycosaminoglycans (GAGs) consisting of hyaluronic acid (85% of the total GAG) and chondroitin sulfate proteoglycan (15% of the total GAG). Neither heparan sulfate proteoglycan nor dermatan sulfate proteoglycan was detected. In the aorta, GAGs are synthesized mainly by arterial smooth muscle cells and endothelial cells. Among these cells, the arterial smooth muscle cell is the principal cell type that synthesizes aortic GAGs, predominantly chondroitin sulfate proteoglycan, whereas the endothelial cell synthesizes small amounts of GAGs, predominantly heparan sulfate proteoglycan. Therefore, the results of this study suggest that the tumor cells of the present case have a property similar to arterial smooth muscle cells in terms of GAG synthesis, and that the tumor originated most probably from arterial smooth muscle cells.

Aortic Diseases↗
PubMed1990

Beta 2-microglobulin amyloidosis in hemodialysis patients. An autopsy study of intervertebral disks and posterior longitudinal ligaments.

Ninety-five autopsy cases of chronic renal failure, which had or had not been treated by hemodialysis, were examined histologically and immunohistochemically for evidence of amyloid deposition in the intervertebral disks and posterior longitudinal ligaments of the spine. beta 2-Microglobulin (beta 2M) amyloid was not present in non-dialyzed patients with chronic renal failure. In cases showing beta 2M amyloid deposition, the shortest term of hemodialysis was 2 years and 5 months. The incidence of beta 2M amyloidosis tended to increase as the dialysis period was prolonged. An inverse correlation was present between dialysis period and age in 22 cases showing beta 2M amyloid deposition (correlation coefficient: -0.43, p less than 0.05), and beta 2M amyloidosis tended to occur earlier in elderly patients than in younger patients. This suggests that elderly patients are more susceptible to beta 2M amyloidosis. beta 2M amyloid was absent in all of 8 cases of systemic lupus erythematosus which were treated by dialysis for periods ranging from 2 days to 12 years. In these patients, beta 2M amyloidosis may have been prevented by steroids, which had been administered for long periods in all cases. Another amyloid of unknown composition was also frequently present in the intervertebral disks and posterior longitudinal ligaments not only in patients with chronic renal failure but also control patients without chronic renal failure. This amyloid was immunohistologically negative for beta 2M, amyloid A protein, light chain kappa or lambda, prealbumin, and apolipoprotein A-II.

Aging↗
PubMed1990

Hepatoblastoma in an 82-year-old man. An autopsy case report.

An autopsy case of adult hepatoblastoma is presented. The patient was an 82-year-old male with chronic hepatitis of 7 years' duration. The liver tumor was detected 6 months before death. Autopsy revealed a large hepatic tumor occupying about 80% of the entire liver. Histologically, the tumor showed typical features of mixed epithelial- and mesenchymal-type hepatoblastoma. The epithelial component consisted of fetal and embryonal cell types. The mesenchymal component showed primitive spindle-shaped cells with various degrees of cellularity. Chondroid areas and a few foci of osteoid formation were also present.

Aged↗
PubMed1990

The osmoreceptor complex in the rat: evidence for interactions between the supraoptic and other diencephalic nuclei.

1. Experiments were undertaken to provide evidence for the existence of a circuit of neuronal interconnections between the supraoptic nucleus (SON), the ventral anteroventral third ventricular region (including the organum vasculosum of the lamina terminalis; ventral AV3V) and the median preoptic nucleus (MnPO), and to determine the importance of these connections in the osmotic control of the neuronal activity of the SON. Extracellular recordings were made in the urethane-anaesthetized male rat from neurones in one of these three sites, while the other two sites were electrically stimulated. 2. During recording from the SON, electrical stimulus pulses applied either to the ventral AV3V or to the MnPO were followed by orthodromic excitation (OD+) or initial short-duration inhibition followed by long-duration excitation (OD- +) of most SON neurones (44/48). The latency of OD+ or OD+ component of OD- + response produced by electrical stimulation of the MnPO was significantly (paired t test, P less than 0.01) shorter than that by the stimulation of the ventral AV3V. None of the neurones we recorded in the SON was activated antidromically by stimulation of either the ventral AV3V or the MnPO. Pressure injection of lidocaine (10%, 50 nl) into the MnPO reversibly depressed the OD+ effect after stimulation of the ventral AV3V in all the SON neurones tested (11/11), while injection of lidocaine into the ventral AV3V did not affect the OD+ effect after stimulation of the MnPO in most neurones (7/9). Both types of observation are consistent with the presence of an excitatory input to SON through the MnPO. 3. Pressure injection of lidocaine into both the ventral AV3V and the MnPO reversibly blocked the activation of SON neurones following an I.P. injection of 1.5 M-NaCl (1 ml) (ventral AV3V 11/11; MnPO, 10/10 cells tested). Injection of lidocaine at both sites, however, did not prevent activation of SON neurones by hypovolaemia (2 ml of blood was withdrawn through a cannula in the right atrium: ventral AV3V, 4/5; MnPO, 4/4 cells tested). The integrity of connections in the ventral AV3V and MnPO thus appeared to be essential for osmotic activation of the SON. 4. Of the 119 ventral AV3V neurones which were tested for their response to electrical stimulation of the SON, forty-nine neurones showed orthodromic excitation (OD+; n = 33) or initial inhibition followed by excitation (OD- +; n = 16). Thirty of the forty-nine OD+ or OD- + neurones also showed antidromic excitation (AD) after electrical stimulation of the MnPO.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1990

SPS-B, a physiological sleep regulator, from the brainstems of sleep-deprived rats, identified as oxidized glutathione.

We previously reported regarding the "sleep-promoting substance (SPS)," which was isolated from the brainstem extract of sleep-deprived rats, the existence of multiple active components including uridine and SPS-B. Intracerebroventricular infusion of crude SPS-B exhibited significant enhancing effects on both slow wave sleep and paradoxical sleep in unrestrained rats. Further investigation of SPS-B has resulted in its final identification as oxidized glutathione (GSSG, gamma-glutamylcysteinylglycine disulfide). Authentic GSSG similarly administered in rats also significantly enhanced sleep which was indistinguishable from normal physiological sleep. We propose GSSG as a candidate endogenous sleep substance.

Animals↗
PubMed1990

New findings in observations by tubo-tympano-aerodynamic method.

We studied Eustachian tube function of healthy adults by two air flow methods, namely tubo-tympano-aerodynamic graphy by Valsalva maneuvre, and Tyonbee maneuvre during swallowing. We observed for the first time the presence of reciprocal features in normal Eustachian tubes. We also compared the tubal function of the same group using an air flow method and sound transmission method. The results of these observations showed that 77.4% of the subjects were positive for TTAG in Valsalva pattern, and 85.4% for sonometry. It can be inferred that data on the tubal opening in response to Valsalva and Toynbee maneuvres is obtained more easily by sonometry than by TTAG. TTAG, which permits examination of minute changes in air flow dynamics even in healthy Eustachian tubes, provides more important information on tubal function than does sonotubometry.

Adolescent↗
PubMed1990

The enzymatic and molecular characteristics of Saccharomycopsis alpha-amylase secreted from Saccharomyces cerevisiae.

The Saccharomycopsis fibuligera alpha-amylase (Sfamy) gene was expressed in Saccharomyces cerevisiae. The highest productivity of Sfamy was 70 mg per liter of culture broth. We purified Sfamy from the culture broth and identified the NH2 terminal primary sequence. This sequence suggests that the Sfamy gene product is synthesized as a pre-pro-precursor, and the pro-sequence is cleaved after a Lys-Arg sequence with the calpain-like endopeptidase encode by the KEX2 gene, resulting in mature Sfamy protein composed of 468 amino acids. Furthermore, the enzyme Sfamy is a glycoprotein in which one N-linked sugar chain containing mannose residues is attached to the Asn residue at the 198 position. The Km and kcat values were 1.1 x 10(-4) M and 1.4 x 10(2) sec-1, respectively, using amylose (the degree of polymerization n = 18) as a substrate. Moreover, the secondary structure, the location of the secondary elements including alpha-helix, beta-sheet, and loop, and tertiary structure were predicted theoretically on the basis of the molecular structure of Aspergillus oryzae alpha-amylase. Taka-amylase A (TAA). These results indicate that Sfamy protein is composed of main (M) and C-terminal (C) domains. The molecular structure of M domain closely resembles that of TAA, but the C domain appears to be more compact than that of TAA because of deletions at three regions forming turns and one region forming alpha-helix.

Amino Acid Sequence↗
PubMed1990

Specificity of lipoamide dehydrogenase for alpha-keto acid dehydrogenase complexes and the glycine cleavage system.

Rat liver lipoamide dehydrogenase (LipDH) was separated into three types on DE-32 column chromatography, but no difference was observed among them in either immunological reactivity or enzymatic properties. A reconstitution experiment of branched-chain alpha-keto acid dehydrogenase complex (BCKADH) revealed that the most anionic type of LipDH was the most effective for the enzyme complex while the three types of LipDH were the same in the affinity for BCKADH subcomplex. All three types of LipDH were equally effective in reconstituting pyruvate dehydrogenase complex, alpha-ketoglutarate dehydrogenase complex and the glycine cleavage system. However, either pyruvate dehydrogenase or alpha-keto-glutarate dehydrogenase complex appeared to involve a certain LipDH in vivo which was firmly integrated into and hardly dissociable from the complex. A broad specificity of LipDH was observed for the glycine cleavage system. When BCKADH reconstitution experiments were carried out with both LipDHs from various sources and purified rat liver BCKADH subcomplex, the effectiveness of animal LipDHs was proportional to the extent of their immunological reactivity to the anti-rat LipDH antibody. However, BCKADH activity was also restored by a certain bacterial LipDH which had no cross-reactivity with the antibody, and LipDHs from some bacterial species, which reacted well with the antibody, showed no effect for the reconstitution of BCKADH. Thus, the determinant(s) of LipDH for the integration into alpha-keto acid dehydrogenase complexes including BCKADH can be its tertiary and/or quarternary structure rather than its primary and secondary structures.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed1990

[A case of brain metastasis from breast cancer responding to chemoendocrine therapy].

Brain metastasis is one of the most critical metastatic lesion on the treatment of breast cancer. We reported a case with brain metastasis from breast cancer responding to chemoendocrine therapy. The patient was 71 years old female complaining gait disturbance. Solitary brain metastasis and multiple bone metastases of breast cancer were diagnosed by CT scan and bone scintigram. Standard radical mastectomy was done. Estrogen receptor was proved to be positive in both of the tumor and metastatic lymph node. Tamoxifen and UFT were administered as chemoendocrine therapy. Complete response of brain metastasis was recognized in CT scan and gait disturbance was complete recovered two months after the treatment. She is now living well.

Aged↗
PubMed1990

[Locomotor activity and urinary excretion of orthocresol in rats exposed to toluene].

To clarify the effect of toluene on behavior, and to evaluate urinary orthocresol excretion as an indicator of toluene exposure and locomotor activity, we have investigated the urinary orthocresol excretion and levels of locomotor activity in rats exposed to 0-3000 ppm of toluene intermittently for 2 hours. The levels of locomotor activity were measured by a laboratory animal activity measuring apparatus (ANIMEX-III). Exposure of adult male rats to more than 1000 ppm (v/v) of toluene caused an elevation of the urinary orthocresol excretion and a good correlation was noted between the amount of toluene in the air and the urinary orthocresol excretion. Exposure to over 2000 ppm of toluene suppressed the level of locomotor activity, and there was a good correlation between the level of locomotor activity and the urinary orthocresol excretion. Further, rats exposed to 3000 ppm toluene showed elevated levels of locomotor activity during a 10-hour period after exposure. These patterns of urinary orthocresol excretion and the levels of locomotor activity remained unchanged even when rats were exposed to 3000 ppm of toluene intermittently over a 4-day period.

Animals↗