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Biomedical subjects

H Hashimoto

Publications and source records attributed to H Hashimoto.

At least 847 records · Page 47Linked to original sources
PubMed1991

Low cost device for electrotransformation and its application to the highly efficient transformation of Escherichia coli and Enterococcus faecalis.

A simple, low cost device for electrotransformation has been designed and constructed. The cost of the circuit was only $150. Maximum field strength of 12,000 V/cm with an actual time constant up to 11 msec was obtained with a newly designed circuitry and a 0.1-cm electrode gap cuvette. Eschericia coli strains DH1, DH5 alpha, and LE392 were transformed at an efficiency of 10(9)/micrograms DNA with plasmids pUC18 and pBR322. E. faecalis strain OG1X was transformed at an efficiency of 0.9 x 10(5)/micrograms DNA without treatment with glycine.

DNA, Bacterial↗
PubMed1991

Prostaglandin H2 as an endothelium-derived contracting factor and its interaction with endothelium-derived nitric oxide.

The possibility that prostaglandin H2 is an endothelium-derived contracting factor (EDCF) was evaluated in rings of thoracic aorta of spontaneously hypertensive rats (SHR). When the aortic rings were contracted with norepinephrine (10(-7) mol/l) and treated with acetylcholine (10(-5) mol/l), a relaxant response with a peak after approximately 1 min and a contractile response with a peak after approximately 7 min were observed. When these rings were pretreated with a thromboxane A2/prostaglandin H2 receptor antagonist (ONO-3708), the later contractile response was clearly inhibited and only a sustained relaxant response was observed. This relaxant response was completely inhibited by pretreatment with an inhibitor of nitric oxide production (N-nitroarginine methylester; NNM). When aortic rings in the basal condition were treated with NNM and then with acetylcholine, a contractile response with a peak after 7 min was observed, but this reaction was completely inhibited by pretreatment with ONO-3708. The rate of 6-keto-prostaglandin F1 alpha production showed a peak of 1.4 x 10(-6) mol/l per min per tissue, 2-4 min after administration of acetylcholine. With exogenous prostaglandin H2 (5 x 10(-7) mol/l), a peak contraction was observed after approximately 4 min, the degree and pattern of which were similar to that induced by acetylcholine. Endogenous prostaglandin H2 is considered to be produced by the aortic rings in an amount sufficient to induce vascular contraction within 30 s, and the pattern of this contraction induced by acetylcholine resembles that induced by exogenous prostaglandin H2. These findings most strongly suggest that prostaglandin H2 is an EDCF.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMed1991

Bilateral open laminoplasty using ceramic laminas for cervical myelopathy.

Evaluation was done of 65 patients with cervical myelopathy treated by bilateral open laminoplasty using artificial laminas, between 1984 and 1988, who had been followed for more than 2 years. The mean recovery rate on the Japanese Orthopaedic Association scoring system was 65% in all cases, and 72% in the cases with no other complications. The artificial laminas appeared well adapted to the laminas in computed tomography and dynamic radiographic examinations, and there were no cases of reduction of the enlarged canal. Postoperative restriction of the range of motion of the cervical spine was lessened by the positioning of lateral grooves, more appropriate external fixation, and posterior flexion exercise after operation. This procedure is not technically complicated, it does not involve appreciable blood loss during operation, it prevents grafted free fat from migrating into the spinal canal, and is advantageous for posterolateral bone chip grafting.

Ceramics↗
PubMed1991

Impaired tumour necrosis factor-alpha (TNF-alpha) production and abnormal B cell response to TNF-alpha in patients with systemic lupus erythematosus (SLE).

We examined the TNF-alpha activity in culture supernatants of monocytes isolated from the peripheral blood of patients with SLE and of normal individuals. The monocytes from patients with SLE stimulated with silica particles, lipopolysaccharide or Staphylococcus aureus Cowan 1 secreted significantly lower amounts of TNF-alpha than did normal monocytes. A decreased TNF mRNA expression was observed in peripheral blood mononuclear cells stimulated by mitogens from patients with SLE. Furthermore, we examined the effect of recombinant TNF-alpha (rTNF-alpha) on the B cell function in SLE patients. rTNF-alpha inhibited the spontaneous B cell proliferation of SLE, but tended to enhance the normal B cell proliferation. Spontaneous IgM production from SLE B cells was inhibited by rTNF-alpha, but that from normal B cells was not. Spontaneous IgG production was unaffected by rTNF-alpha. Also, rTNF-alpha did not affect the viability of B cells. These findings suggest that an impaired TNF-alpha production and an abnormal B cell response to TNF-alpha play a role in the immunological dysfunction in patients with SLE.

B-Lymphocytes↗
PubMed1991

Primary localized amyloidosis in one family.

Primary localized amyloidosis was found in a family. A 66-year-old woman had suffered from hoarseness for 18 years. A biopsy specimen from the larynx showed amyloid deposits in the submucosal connective tissue. Her 40-year-old daughter noticed a subcutaneous nodule on her philtrum. Histologic examination showed the deposition of amyloid in the middle and lower dermis, which also encased the blood vessels and epidermal appendages. In both cases the amyloid deposits were positively stained with Congo red and the staining was resistant to potassium permanganate treatment. These amyloid deposits were strongly positive against the anti-amyloid antibody of the lambda light chain. These results indicate that the amyloid substance is derived from protein AL. There was no clinical or laboratory evidence of systemic amyloidosis or multiple myeloma in either patient.

Adult↗
PubMed1991

Tubular adenoma of the gallbladder with squamoid spindle cell metaplasia. Report of three cases with immunohistochemical study.

Three cases of tubular adenoma of the gallbladder with squamoid spindle cell metaplasia are reported. Two of the three patients, who were middle-aged Japanese, had a solitary polyp in the gallbladder, and the other had three polyps. All the lesions were detected incidentally by ultrasonography. The polyps were pedunculated with a fine or frail stalk, and ranged from 0.5 to 3.9 cm in diameter. Histologically, they were tubular adenomas accompanied by scattered foci composed of a compact collection of short-spindle or oval cells with mild atypia. These cells did not retain intercellular bridges, and lacked intracellular keratinization. Immunohistochemically, the spindle cells stained positively for high-molecular-weight cytokeratin (EAB 903, a marker of squamous cell differentiation), whereas adenoma cells lining the tubules were negative for this antigen. Therefore, the spindle cell component is considered to represent squamoid metaplasia of adenoma cells.

Adenoma↗
PubMed1991

Evidence for a link between mechanical and electrical alternans in acutely ischaemic myocardium of anaesthetized dogs.

In order to examine the relation between mechanical alternans and associated electrical alternans during acute myocardial ischaemia, we determined the effect of a ventricular premature beat and calcium antagonists on mechanical and electrical alternans during acute coronary occlusion in anaesthetized dogs. Isometric contractions and unipolar electrocardiograms were recorded from ischaemic myocardium. During coronary occlusion, mechanical alternans was accompanied by electrical alternans, which was an alternate change in the ST segment elevation, i.e. the higher ST and the lower ST. Electrical alternans was frequently discordant and in some cases accompanied by discordant mechanical alternans. Both discordant electrical and mechanical alternans became concordant and were potentiated after the ventricular premature beat. In all cases, concordant mechanical alternans was accompanied by concordant electrical alternans and vice versa. In this situation, the higher and the lower ST corresponded to the larger and the smaller contractions respectively. Thus, a fixed correspondence was observed between mechanical and electrical alternans. A fixed correspondence was also observed between mechanical alternans and the variation in the time taken for repolarization of the monophasic action potential. Verapamil and diltiazem inhibited both electrical and mechanical alternans. The present results support the idea that a common mechanism, such as a beat-to-beat cycle of the transmembrane and intracellular movement of calcium ions, may play a role in the mechanisms of electrical and mechanical alternans.

Animals↗
PubMed1991

Glomerular dysfunction in nephrotic humans with minimal changes or focal glomerulosclerosis.

Fractional clearances (theta) of uncharged dextrans (radii 28-60 A) were used to characterize glomerular dysfunction in 34 nephrotic humans with either minimal-change nephropathy (MCN) or focal, segmental glomerulosclerosis (FSGS). A theoretical analysis of theta of dextran with a heteroporous membrane model revealed a similar alteration, more marked in FSGS than MCN. The number of restrictive pores perforating the major membrane component was reduced in parallel with the prevailing glomerular filtration rate (GFR). Parallel shuntlike pores in the remaining membrane component were more prominent, pointing to impaired size selectivity. However, the theta of large (60 A) dextrans attributable to these shunts exceeded control in FSGS only, suggesting that coexistent impairment of charge selectivity contributed importantly to the proteinuria in MCN. Membrane properties returned toward normal when MCN remitted. Glomerular morphometry revealed the frequency of epithelial filtration slits to vary with the extent of membrane dysfunction. Despite offsetting hypertrophy of remnant glomeruli in FSGS, a loss of filtration surface due to sclerosis likely contributed to the more marked reductions in pore number and GFR observed in this disorder than in MCN.

Adolescent↗
PubMed1991

A differential alteration in the responsiveness of isolated cardiac muscles to alpha- and beta-adrenergic agonists in DOCA-salt hypertensive rats.

We examined the alteration of the responsiveness to adrenergic agonists and changes in the density of adrenoreceptors in the hearts of rats with deoxycorticosterone acetate (DOCA)-salt hypertension in order to determine the relationship between changes in adrenoreceptor responsiveness and adrenoreceptor density in this hypertension model. The maximal increase in the tension development with phenylephrine in the presence of propranolol and with isoproterenol decreased to a larger extent in the latter, but the PD2 values for these agonists did not change. Decreases in maximal tension development with phenylephrine and Ca2+ were similar. The density of alpha- and beta-adrenoceptors decreased similarly. In conclusion, whereas a decreased adrenoreceptor density may not significantly contribute to a decreased agonist responsiveness in DOCA-salt hypertensive rats, altered Ca2+ sensitivity contributes to the observed reduction in agonist responsiveness.

Adrenergic alpha-Agonists↗
PubMed1991

Separation and characterization of three positional isomers of dimaltosyl-cyclomaltoheptaose (dimaltosyl-beta-cyclodextrin).

A mixture of maltosylcyclomaltoheptaoses (maltosyl-beta-cyclodextrins, G2-beta CDs) was prepared from maltose and beta-cyclodextrin (beta CD) through the reverse action of Klebsiella pneumoniae pullulanase. Three positional isomers of dimaltosyl-beta CD in the mixture were separated by high-performance liquid chromatography on a reversed phase column and a graphitized carbon column. Their molecular weights were measured by fast-atom bombardment mass spectrometry, and the structures were established by methylation analysis, hydrolysis with glucoamylase to the known compounds, three positional isomers of diglucosyl-beta CD, and 13C-nuclear magnetic resonance spectroscopy.

Cyclodextrins↗
PubMed1991

Coupling interval-related effects of class I antiarrhythmic drugs, mexiletine, cibenzoline and disopyramide, on ventricular activation in canine myocardial infarction.

Time-dependent inhibition of sodium channels by class I antiarrhythmic drugs has been observed in isolated cardiac muscles or cells. We examined coupling interval-related effects of class I antiarrhythmic drugs, mexiletine, cibenzoline and disopyramide, on ventricular activation in canine infarcted myocardium. A ventricular stimulation with various coupling intervals was applied to the right ventricle, and activation delays (time intervals between the initiation of a deflection and the final rapid deflection of a bipolar electrocardiogram) of infarcted and normal zones were measured. The premature stimulation produced a delayed activation and in some animals, caused reentrant beats. Mexiletine (3 and 10 mg/kg), cibenzoline (1 and 4 mg/kg) and disopyramide (1 and 4 mg/kg) further enhanced or blocked the delayed activation. The effects of these drugs were more marked at shorter coupling intervals, although cibenzoline and disopyramide showed significant effects also at long coupling intervals. The effect of these drugs on the activation in the normal zone was less than that in the infarcted zone. In conclusion, mexiletine, cibenzoline and disopyramide showed a coupling interval-related depression of delayed activation in infarcted myocardium, which may be a reflection of their time-dependent inhibition of sodium channels.

Animals↗
PubMed1991

Maturation of the pituitary-thyroid axis during the perinatal period.

To clarify the maturation process of the pituitary-thyroid axis during the perinatal period, thyrotropin (TSH) response to thyrotropin releasing hormone (TRH) and serum thyroid hormone levels were examined in 26 healthy infants of 30 to 40 weeks gestation. A TRH stimulation test was performed on 10 to 20 postnatal days. Basal concentrations of serum thyroxine (T4), free thyroxine (free T4) and triiodothyronine (T3) were positively correlated to gestational age and birth weight (p less than 0.001-0.01). Seven infants of 30 to 35 gestational weeks demonstrated an exaggerated TSH response to TRH (49.7 +/- 6.7 microU/ml versus 22.1 +/- 4.8 microU/ml, p less than 0.001), which was gradually reduced with gestational age and normalized after 37 weeks gestation. A similar decrease in TSH responsiveness to TRH was also observed longitudinally in all of 5 high responders repeatedly examined. There was a negative correlation between basal or peak TSH concentrations and postconceptional age in high responders (r = -0.59 p less than 0.05, r = -0.66 p less than 0.01), whereas in the normal responders TSH response, remained at a constant level during 31 to 43 postconceptional weeks. On the other hand, there was no correlation between basal or peak TSH levels and serum thyroid hormones. These results indicate that (1) maturation of the pituitary-thyroid axis is intrinsically controlled by gestational age rather than by serum thyroid hormone levels, (2) hypersecretion of TSH in preterm infants induces a progressive increase in serum thyroid hormones, and (3) although there is individual variation in the maturation process, the feedback regulation of the pituitary-thyroid axis matures by approximately the 37th gestational week.

Birth Weight↗
PubMed1991

Fatty acid composition in 1,2-diacylglycerol of diabetic and insulin-treated diabetic rat hearts.

Elevated levels of 1,2-diacylglycerol (DG) have been observed in streptozotocin-induced diabetic and insulin-treated diabetic rat hearts. The fatty acid moieties of 1,2-DG are considered to be related to its ability to activate protein kinase C. Therefore, we determined the fatty acids of 1,2-DG by gas chromatography and compared them with those of triglycerides in the myocardium. The triglyceride content returned to control levels after 4 weeks of untreated diabetes followed by 4 weeks of insulin treatment. There was a significant difference in the fatty acid composition of triglycerides between diabetic and control rats. Insulin treatment also returned the fatty acids of triglycerides in diabetes to the profile observed in control rats. On the other hand, insulin treatment of the diabetic rats did not normalize 1,2-DG content and its fatty acid composition. Fatty acid analysis of 1,2-DG showed that its profile in insulin-treated diabetic rats was different from that of either control or diabetic rats, suggesting that insulin-induced 1,2-DG differs from that seen in cases of diabetes.

Animals↗
PubMed1991

Spontaneous intracerebral hemorrhage in cases of severe angiospasm following ruptured aneurysm--a pathological study.

Eleven patients with a history of moderate or severe angiospasm following ruptured cerebral aneurysm developed spontaneous intracerebral hemorrhage between 31 and 111 months after aneurysm surgery. In all cases, hemorrhage occurred in the ipsilateral hemisphere to the original aneurysm. In nine patients, the hematoma was surgically evacuated and bleeding perforating arteries were resected for histological examination. Computed tomographic scans showed the hematomas to be unusually extended compared to those after hypertensive intracerebral hemorrhage. The histological examination showed various degenerative changes in the elastic lamina and media of the perforating arteries, even though most patients were young and normotensive. These findings suggest that patients who have suffered severe cerebral angiospasm may have a higher risk for subsequent development of intracerebral hemorrhage than those without prior angiospasm.

Aged↗
PubMed1991

1,2-diacylglycerol content and its fatty acid composition in thoracic aorta of diabetic rats.

These experiments were conducted to determine 1,2-diacylglycerol (DAG) in the thoracic aorta obtained from streptozocin-induced diabetic rats because 1,2-DAG is assumed to be a second messenger associated with phosphoinositide metabolism. After preincubation for a 25-min stabilization, 1,2-DAG content in isolated thoracic aortas 4 and 8 wk after streptozocin injection was significantly decreased by 42 and 31%, respectively, compared with age-matched control rats on 10-min norepinephrine stimulation (10(-5) M). However, 4 wk of daily insulin injection after 4 wk of untreated diabetes significantly shifted 1,2-DAG toward normal levels. Analysis of its fatty acid composition showed a significant difference between control and diabetic rat aortas at both 4 and 8 wk. In particular, the percentage of arachidonate, a precursor of eicosanoids, decreased. Such alteration in the fatty acid profile in diabetic rat aortas was inhibited by insulin treatment. 1,2-DAG content in the 8-wk diabetic group was also significantly decreased by 33% compared with control in the absence of norepinephrine, whereas 1,2-DAG content was lower than in the presence of norepinephrine in both the control and diabetic groups. Cholesterol, triglyceride, and phosphatidylcholine content in diabetic rat aortas was lower than control. Lower levels of 1,2-DAG in the thoracic aorta from diabetic rats were observed in the presence and absence of norepinephrine, suggesting that a defect in 1,2-DAG production may be associated with abnormalities of vascular smooth muscle responsiveness by agonists, as described previously.

Animals↗
PubMed1991

[Percutaneous management of benign ureteroileal anastomotic strictures after ileal conduit urinary diversion].

We report our experience with the endourological treatment of 4 patients with 5 benign ureteroileal anastomotic strictures after ileal conduit urinary diversion. The treatment was successful in 4 of the 5 renal units without restenosis with a mean follow up of 10 months. The strictures were dilated by ureteral dilators and/or balloon dilation catheters using guide wires through percutaneous nephrostomies in an antegrade fashion. A 9 or 12 Fr. percutaneous splint catheter or a 12 Fr. double pig tail catheter was placed for 3-8 weeks after a successful dilation. Two renal units underwent repeated dilations. In 1 renal unit, a guide wire was hardly passed through the stricture and the treatment was unsuccessful. No serious complications were encountered. Percutaneous endourological managements of ureteroileal anastomotic strictures seemed to be quite versatile techniques which should be tried as the initial approach in many cases.

Anastomosis, Surgical↗