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Biomedical subjects

M Yoshii

Publications and source records attributed to M Yoshii.

At least 73 records · Page 4Linked to original sources
PubMed1994

Comparative studies of metabolism of simultaneously administered chenodeoxycholic acid and ursodeoxycholic acid in hamsters.

We present the comparative studies of metabolism of chenodeoxycholic acid and ursodeoxycholic acid and their taurine conjugates in the liver and fecal culture from hamsters. When [24-14C]chenodeoxycholic acid and [11,12-3H]ursodeoxycholic acid were simultaneously instilled into the jujunal loop of bile fistula hamsters, both bile acids administered were recovered mainly as their conjugates with taurine and glycine in the fistula bile. The recovery of chenodeoxycholic acid was slightly but significantly higher than that of ursodeoxycholic acid. Chenodeoxycholic acid was more efficiently conjugated with glycine than ursodeoxycholic acid. The glycine/taurine ratio in the biliary chenodeoxycholic acid was 1.9, and that in ursodeoxycholic acid was 1.6. In addition, as much as 6.2% of ursodeoxycholic acid was excreted as the unconjugated form; on the other hand only 2.4% of unconjugated chenodeoxycholic acid was excreted. When [24-14C]chenodeoxycholyltaurine and [11,12-3H]ursodeoxycholyltaurine were simultaneously administered into the ileum loop of bile fistula hamsters, both bile salts were absorbed and secreted efficiently into the bile at the same rate. These results indicate that slightly lower recovery of ursodeoxycholic acid in the bile could be due to the less effective conjugation of ursodeoxycholic acid than chenodeoxycholic acid in the liver. Deconjugation by fecal culture from a hamster proceeded more rapidly in chenodeoxycholyltaurine than ursodeoxycholyltaurine. 7-Dehyroxylation to form lithocholic acid by fecal culture was also faster in chenodeoxycholic acid than ursodeoxycholic acid. The formation of 7-oxolithocholic acid from ursodeoxycholic acid was lesser than from chenodeoxycholic acid. In summary, bacterial deconjugation followed by 7-dehydroxylation to form lithocholic acid seems to be achieved more efficiently with chenodeoxycholic acid than ursodeoxycholic acid.

Animals↗
PubMed1994

Possible noradrenergic dysfunction in schizophrenia.

In spite of extensive studies over the last 2 decades to find direct evidence in support of the dopamine hypothesis of schizophrenia, no undisputed experimental data has been obtained. In contrast, estimation of noradrenalin (another major catecholamine) and its metabolites in postmortem brain and in the cerebrospinal fluid appears to be producing consistent results. To understand the meaning of this change for the pathogenesis of the illness, we have carried out animal experiments in which reproducibility of schizophrenic signs and symptoms by noradrenergic dysfunction, and treatability of the disorder by modulation of noradrenergic activity were studied. First, psychophysiological signs in skin conductance responsiveness (nonhabituating or nonresponding change) and smooth pursuit eye movement (spiky or stepwise pursuit) could be reproduced by enhancing or suppressing central noradrenergic activity. Behavioral abnormalities resembling schizophrenic symptoms are known to be reproducible by over- or underactivity of the system (overarousal or underarousal syndrome). Secondly, the action of various drugs capable of modulating schizophrenic symptoms was analyzed in relation to noradrenergic activity. Haloperidol, in particular, had a potent suppressing effect on skin conductance activity (spontaneous fluctuation rate and habituation rate) when administered chronically, suggesting its inhibitory action on noradrenergic activity.

Animals↗
PubMed1994

A region of the muscarinic-gated atrial K+ channel critical for activation by G protein beta gamma subunits.

Complementary DNAs encoding two types of inwardly rectifying K+ channels, GIRK1 and IRK1, have been cloned from rat atrium and mouse macrophage, respectively. GIRK1 expressed in Xenopus oocytes was activated by acetylcholine when m2 muscarinic acetylcholine receptor was coexpressed. The acetylcholine-induced activation of GIRK1 was enhanced by coexpression with the G protein beta 1 gamma 2 subunit but not the beta 1 gamma 1 or alpha subunits. Deletion of the C-terminus of GIRK1 impaired the channel activation associated with the beta 1 gamma 2 subunit. Moreover, replacement of the C-terminus of IRK1 with that of GIRK1 produced a chimera channel that was activated by the beta 1 gamma 2 subunit, whereas intact IRK1 was not activated by the beta 1 gamma 2 subunit. These findings define the C-terminus of GIRK1 as a regulatory region for the G protein beta gamma subunit.

Animals↗
PubMed1994

[Urethral opening pressure as a parameter for introduction of the proper voiding modality in myelodysplastic patients].

To introduce the proper voiding modality to patients with myelodysplasty, urethral opening pressure (UOP), an intravesical pressure just at the beginning urine flows out beyond the external urethral sphincter, was measured in 63 myelodysplastic patients. Among 45 renal units with any morphological or functional changes at the first UOP measurement, 37 units (82.2%) were included in the high UOP group (> or = 35 cmH2O). And among 41 ureters with VUR of more than grade 2, 32 (78.0%) were in the high UOP group. In addition, deformity of the urinary bladder was observed in 36 patients, and 26 (72.2%) of these bladders showed high UOP values. Therefore, all the patients could be divided into two groups: high UOP group (> or = 35 cmH2O, 28 cases) and low UOP group (< 35 cmH2O, 35 cases). Twenty-three patients (82.1%) with high UOP values had been mainly treated with clean intermittent catheterization (CIC). In contrast, 24 patients (68.6%) with low UOP values had been allowed to urinate by Credè' or Valsalva's method. In the followup study for 40 to 44 months, patients in the CIC group obtained good prognosis as for morphological or functional changes of the urinary tract. On the other hand, patients in the Credè' or Valsalva's method group showed a significantly higher deterioration rate in the high UOP group (80.0%) than that in the low UOP group (9.1%) (p < 0.005). From these results, hopely that in myelodysplastic patients with the underactive detrusor, CIC may be introduced for low pressure voiding to those who show high UOP values as early as possible. On the other hand, those who show low UOP values may be managed with Credè' or Valsalva's method as well as CIC. Thus, UOP is considered a possible prognostic factor for the morphological and functional changes of the urinary tract, which may be a useful parameter in decision of voiding modalities in myelodysplastic patients.

Adolescent↗
PubMed1994

Bile salts of the toad, Bufo marinus: characterization of a new unsaturated higher bile acid, 3 alpha,7 alpha,12 alpha,26-tetrahydroxy-5 beta-cholest-23-en-27-oic acid.

The bile salts present in gallbladder bile of the toad, Bufo marinus, were found to consist of a mixture of bile alcohol sulfates and unconjugated bile acids. The major bile alcohol was 5 beta-bufol; 5 alpha- and 5 beta-cholestane-3 alpha,7 alpha,12 alpha, 26-tetrols occurred as the minor bile alcohols. Bile acids of Bufo marinus were cholic acid, allocholic acid, 3 alpha,7 alpha,12 alpha-trihydroxy-5 alpha- and 5 beta-cholestan-26-oic acids, 3 alpha,7 alpha,12 alpha-trihydroxy-5 alpha- and 5 beta-cholest-23-en-26-oic acids, 3 alpha,7 alpha,12 alpha, 26-tetrahydroxy-5 beta-cholestan-27-oic acid, and a C27 bile acid which has not been previously described. By chromatographic behavior, mass spectral data, and identification of the products of catalytic hydrogenation and ozonolysis, the structure of the new higher bile acid was elucidated as 3 alpha,7 alpha,12 alpha,26-tetrahydroxy-5 beta-cholest-23-en-27-oic acid. The bile salt pattern of Bufo marinus closely resembles that of Bufo vulgaris formosus, except for the absence of 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholest-22-ene-24-carboxylic acid, the major bile acid of the latter toad.

Animals↗
PubMed1993

Differential inhibition of transient and long-lasting calcium channel currents by benzodiazepines in neuroblastoma cells.

The effects of diazepam, nitrazepam, clonazepam, and Ro5-4864 on transient (type I) and long-lasting (type II) calcium channels associated with low-affinity benzodiazepine receptors were investigated using the whole-cell patch-clamp technique. Clonazepam (100 microM), a specific agonist for the central-type benzodiazepine receptor, reduced transient currents through the type I calcium channel by 40% without affecting long-lasting currents through the type II calcium channel. Diazepam and nitrazepam (100 microM), non-specific agonists for both the central- and peripheral-type benzodiazepine receptors, reduced both transient and long-lasting currents equally by 25-30%. A similar non-selective inhibition was observed by Ro5-4864 (1-10 microM), a specific agonist for the peripheral-type benzodiazepine receptor. It is concluded that the two calcium channel types are regulated differentially by two different kinds of benzodiazepines; central-type for type I channel and peripheral-type for both type I and type II channels.

Animals↗
PubMed1993

Peliosis of the spleen with intraperitoneal hemorrhage.

We encountered a patient with steroid-related peliosis of the spleen, a rare disease characterized by multiple blood-filled cavities in the splenic parenchyma, with spontaneous intraperitoneal hemorrhage. The ultrasonographic, computed tomographic, and angiographic images were compared with pathologic findings of the material obtained surgically.

Aged↗
PubMed1993

Renal ablation with absolute ethanol for nonfunctioning hydronephrosis.

Six adult patients underwent renal ablation with absolute ethanol for nonfunctioning hydronephrosis due to various ureteral lesions. The procedure of renal ablation consisted of 3 separate sessions: placement of percutaneous nephrostomy; transarterial embolization of the renal artery with absolute ethanol, and sclerotherapy of the renal pelvis and ureter through nephrostomy with absolute ethanol. Marked shrinkage of the treated kidney was observed in all cases without any major adverse effects throughout the observation period. Renal ablation with absolute ethanol for nonfunctioning hydronephrosis constitutes a safe and less invasive alternative to surgical nephrectomy to preserve the quality of life of the patients.

Adult↗
PubMed1993

Hyperparathyroidism--comparison of flash imaging with spin echo MR imaging.

MR images of the neck were prospectively studied in 19 patients with hyperparathyroidism. Fast low angle shot (FLASH) sequence was performed in addition to T1- and T2-weighted spin echo (SE) sequences. FLASH images were obtained with 320/12/20 degrees (TR/TE/flip angle) using presaturation technique. TE of 12 ms was chosen to eliminate high signal of fat tissue. In the evaluation of detectability, a combination of T1-weighted SE and FLASH images (T1WI + FLASH) was compared with a combination of T1- and T2-weighted SE images (T1WI + T2WI). MR imaging correctly depicted 20 of 30 abnormal glands on both T1WI + FLASH and T1WI + T2WI. FLASH imaging effectively eliminated high signal of fat tissue. Nineteen abnormal glands demonstrated higher signal than surrounding tissues on FLASH images, whereas 12 glands were high-intense on T2-weighted SE images. We conclude that FLASH imaging provides improved tissue contrast and anatomic delineation and, thus, may replace T2-weighted SE imaging in the neck.

Adenoma↗
PubMed1993

[Antireflux operation for vesicoureteral reflux in spina bifida patients].

A series of 32 patients with spina bifida, representing 50 renal units with vesicoureteral reflux (VUR), was treated with antireflux operation. All but one patient underwent ureteral reimplantation with Cohen's technique. Another patient was treated with bilateral Politano-Leadbetter's technique. The overall success rates were 92.0% by renal unit and 87.5% by case, with a mean follow-up period of 42.5 months. These results were comparable to those in the recent literature. Failure included recurrence of VUR in 3 patients. Another patient who had undergone unilateral reimplantation developed new occurrence of reflux in the contralateral ureter. Possible masking of contralateral VUR should be taken into consideration in patients with unilateral high grade VUR. We also emphasize the importance of continuing clean intermittent catheterization in a proper manner to be free of VUR postoperatively.

Adolescent↗
PubMed1993

[Unresolved issues concerning the operative indication of augmentation cystoplasty in spina bifida patients: a report of two cases].

Augmentation cystoplasty is evolving into a common method of surgical treatment for a low capacity and/or low compliance neurogenic bladder. Although an increasing number of successful results have been recently reported, the operative indication of augmentation cystoplasty is yet to be established. Herein, we report two cases of neurogenic bladder due to spina bifida which required abandonment of augmentation cystoplasty. The first case was in a 23-year-old female with a severely deformed bladder and right vesicoureteral reflux (VUR). She refused to undergo ileocystoplasty because we could not assure her of postoperative conception which she eagerly anticipated. The second case was in a 19-year-old male with a severely deformed bladder and right VUR. He experienced recurrent episodes of ventriculoperitoneal shunt (V-P shunt) difficulty which required exchanging the shunt tube each time, and each exchange proved to be very difficult or nearly impossible. Based on lengthy neurosurgical consultation, we came to the conclusion that ileocystoplasty was not a preferable treatment of choice for the correction of his disease due to the possibility of V-P shunt infection, which could be fatal. Alternatively, both cases were treated with Cohen's ureteral reimplantation, which resulted in the recurrence of VUR. These cases presented still unresolved issues concerning the operative indication of augmentation cystoplasty in spina bifida patients.

Adult↗
PubMed1993

Bile acid sulfonates alter cholesterol gallstone incidence in hamsters.

The prevention of cholesterol gallstone formation by three bile acid analogs, sodium 3 alpha,7 alpha-dihydroxy-5 beta-cholane-24- sulfonate, sodium 3 alpha,7 beta-dihydroxy-5 beta-cholane-24-sulfonate and sodium 3 alpha,6 alpha-dihydroxy-5 beta-cholane-24-sulfonate, was examined in a hamster model of cholesterol cholelithiasis. Sodium taurochenodeoxycholate, sodium tauroursodeoxycholate and sodium taurohyodeoxycholate were studied simultaneously for comparison. Gallstones and cholesterol crystals were induced in 14 of 15 hamsters fed a bile acid-free, semipurified lithogenic diet containing 0.3% cholesterol and 4% butterfat for 6 wk. The addition of 0.1% sodium taurochenodeoxycholate and sodium tauroursodeoxycholate to the lithogenic diet had little effect on the formation of gallstones or biliary cholesterol crystals. In contrast, sodium 3 alpha,7 alpha-hydroxy-5 beta-cholane-24- sulfonate and sodium 3 alpha,7 beta-dihydroxy-5 beta-cholane-24-sulfonate, when fed at the same dose, prevented cholesterol gallstone formation significantly. Sodium taurohyodeoxycholate and sodium 3 alpha,6 alpha-dihydroxy-5 beta-cholane- 24-sulfonate inhibited cholesterol gallstone formation effectively. The cholesterol saturation index of bile was greater than 1.00 in all groups, with the exception of the group fed sodium 3 alpha,7 alpha-dihydroxy-5 beta-cholane-24-sulfonate. Liver and serum cholesterol levels tended to be lower in most of the groups that were fed bile acids. This effect was most pronounced in the animals receiving sodium taurohyodeoxycholate. At the end of the experiment, the administered sulfonate analogs were detected in gallbladder bile.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Metabolism of sulfonate analogs of ursodeoxycholic acid and their effects on biliary bile acid composition in hamsters.

The metabolism of sodium 3 alpha,7 beta-dihydroxy-5 beta-cholane-24-sulfonate and sodium 3 alpha,7 beta-dihydroxy-24-nor-5 beta-cholane-23-sulfonate was studied in hamsters. In bile fistula animals these sulfonate analogs of ursodeoxycholic acid were absorbed mainly from the terminal ileum and secreted rapidly into the bile without biotransformation or conjugation. After oral administration, the sulfonate analogs were excreted in the feces at the same rate as chenodeoxycholic acid and its metabolic products. The intestinal microorganisms transformed chenodeoxycholic acid largely into lithocholic acid; the sulfonate analogs were completely resistant to biotransformation. After a 2-week feeding period, the sulfonate analogs of ursodeoxycholic acid accounted for 24.0% and 16.9% of total biliary bile acids. These sulfonates did not affect the proportions of the natural bile acids in the bile, and the ratio of glycine-conjugated bile acids to taurine-conjugated bile acids was not altered by feeding the sulfonates. In contrast, when ursodeoxycholic acid was fed, the proportions of the natural bile acids and the glycine/taurine ratio were changed. These results suggest that the sulfonate analogs had no profound effect on endogenous bile acid metabolism and did not cause a depletion of the hepatic taurine pool during enterohepatic circulation. The sulfonates had no effect on intestinal cholesterol absorption and serum cholesterol levels.

Animals↗
PubMed1992

Inhibitory effects of psychotomimetic sigma ligands on nicotine-induced K+ flux from differentiated PC12 cells.

In NGF-treated PC12 cells, nicotine-induced K+ release was measured with a K(+)-sensitive microelectrode. The K+ outflow via nicotinic ACh receptor cation channels was inhibited by various psychotomimetic sigma ligands in the sequence of PCP, dextromethorphan >> DTG, MK 801, (+)SKF10047 >> (+)3-PPP. The K+ release was not affected by the neuroleptic sigma ligand haloperidol nor by the calcium antagonist nifedipine. The results suggest that psychotomimetic sigma ligands inhibit nicotine-stimulated K+ flux by interacting with nicotinic, rather than via sigma 2 receptors.

Animals↗
PubMed1992

Synthesis of sulfonate analogs of bile acids.

Sulfonate analogs of C23 and C24 bile acids were synthesized from norcholic, norchenodeoxycholic, norursodeoxycholic, nordeoxycholic, norhyodeoxycholic, cholic, deoxycholic, hyodeoxycholic, and lithocholic acids. The principal reactions used were (1) reduction of the bile acids with NaBH4 to the corresponding bile alcohols, (2) selective tosylation of the terminal hydroxyl group, (3) iodination of the tosyl esters with NaI, and (4) treatment of the iodides with Na2SO3 to form the sulfonate analogs of the bile acids. The sulfonate analogs showed polarity similar to that of taurine-conjugated bile acids on thin-layer chromatography. The carbon 13 nuclear magnetic resonance spectral data for the sulfonate analogs were tabulated.

Bile Acids and Salts↗
PubMed1992

Modulation of ion channels by somatostatin and acetylcholine.

Somatostatin and muscarinic acetylcholine receptors are similar as far as modulation of voltage-gated Ca2+ channels and anomalously rectifying K+ channels are concerned. Activation of either type of receptors induces inhibition of Ca2+ channels and activation of anomalous K+ channels without depending on intracellular cAMP. Somatostatin appears to act on the same receptor subtype for these two actions since somatostatin receptors are homogenous in pituitary cells (Srikant and Patel, 1982; Tran et al., 1985) where the peptide produces these two effects as well as an inhibition of adenylate cyclase. In the case of muscarinic receptors, however, it remains unclear whether the same subtype of receptors is involved in both inhibition of Ca2+ channels and activation of K+ channels. Activation of muscarinic receptors in hippocampal neurones evidently produces a cAMP-independent suppression of Ca2+ channel. In cardiac cells, however, muscarinic stimulation does not cause a cAMP-independent suppression of Ca2+ channels but does activate an anomalous rectifier. These findings do not necessarily mean that the muscarinic receptor involved in the inhibition of Ca2+ channels in hippocampal neurones is not of m2 type which is assumed to mediate the activation of anomalous K+ channels in cardiac cells. There is no evidence that cardiac Ca2+ channels are identical to hippocampal Ca2+ channels susceptible to muscarinic inhibition. In addition, a similar argument could be applied to G proteins coupling muscarinic receptors to Ca2+ channels in neurones and cardiac myocytes. In this regard, it should be noted that activation of GABAB receptors or mu and delta opiate receptors, an event known to inhibit adenylate cyclase activity through a PTX-sensitive Gi protein, also produces both inhibition of Ca2+ channels and activation of anomalous K channels in a cAMP-independent manner. This close correlation between inhibition of adenylate cyclase activity and cAMP-independent modulation of Ca2+ and K+ channels suggests the possible involvement of m2 subtype in the inhibition of Ca2+ channels in hippocampal neurones. Circumstantial evidence indicates that anomalous K+ channels are directly activated by alpha subunits of Gi, but not Go, proteins. The alpha subunit of Go protein seems to mediate inhibition of the Ca2+ channel, probably in a direct manner. The most striking difference between somatostatin and muscarinic receptors would be their opposite actions on the M channel. All the inhibitory receptors on the M channel, including m1 and m3 receptors, are known to stimulate PI hydrolysis via a PTX-insensitive G protein.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholine↗
PubMed1992

Hypocholesterolemic effect of ursodeoxycholylcysteic acid in hamsters fed a high cholesterol diet.

We studied the effect of feeding ursodeoxycholylcysteic acid, the cysteic acid conjugated analog of ursodeoxycholyltaurine, on serum and liver cholesterol levels and on intestinal absorption of cholesterol and bile salts in hamsters. Addition of ursodeoxycholylcysteic acid to the cholesterol-enriched diet reduced the elevation of serum and liver cholesterol levels caused by feeding cholesterol. However, supplementation with ursodeoxycholylcysteic acid to the standard diet did not show any significant change in serum and liver cholesterol levels. Administration of ursodeoxycholylcysteic acid caused a decrease in dietary cholesterol absorption but did not interfere with the ileal transport of endogenous bile salts. Hence the hypocholesterolemic activity of dietary ursodeoxycholylcysteic acid is thought to be the effect on intestinal absorption of cholesterol but not to be the interruption of the enterohepatic circulation of bile salts.

Animals↗