Biomedical subjects

T Yoshimoto

Publications and source records attributed to T Yoshimoto.

At least 487 records · Page 27Linked to original sources

PubMed1995

Prolylcarboxypeptidase (angiotensinase C): purification and characterization of the enzyme from Xanthomanas maltophilia.

Prolylcarboxypeptidase (Angiotensinase C, EC 3.4.16.2) was purified to homogeneity from cell free extracts of Xanthomonas maltophilia by ammonium sulfate fractionation and sequential chromatographies on DEAE-Toyopearl, Sephadex G-150, FPLC-Hiload Superdex 200 pg, and FPLC-Hitrap SP columns, with an activity recovery of 15%. The molecular weight of the enzyme was found to be 330,000 by gel filtration and 83,000 by SDS-PAGE, suggesting a tetrameric form for the native enzyme. It had an optimum pH of 8.5 and stability between pH 8.0 and 11.0. The isoelectric point of the enzyme was 6.6. The enzyme hydrolyzed Pro-X bonds when proline was in the penultimate position from the carboxyl terminal. The enzyme was strongly inhibited by diisopropylfluorophosphate (DFP), while phenylmethylsulfonyl fluoride (PMSF), p-chloromercuribenzoic acid (PCMB), iodoacetamide, and metal chelators had no effect.

Amino Acid Sequence↗

PubMed1995

Dopaminergic regulation of aldosterone secretion: its pathophysiologic significance in subsets of primary aldosteronism.

Although aldosterone (Aldo.) secretion is regulated by various humoral factors, evidence has accumulated to support an involvement of dopaminergic system in its regulation. The pathophysiological significance of the dopaminergic system in primary aldosteronism (PA) however remains unknown. In the present study, we examined the effects of metoclopramide (MCP) on Aldo. secretion in normal subjects (n = 11) and patients with essential hypertension (EH, n = 8), aldosterone-producing adenoma (APA, n = 10), and idiopathic hyperaldosteronism (IHA, n = 6). Plasma Aldo., prolactin (PRL), renin, cortisol, serum sodium, and serum potassium levels were determined before and 30 min after i.v. bolus injection of 10 mg MCP at 9 a.m. Plasma Aldo. showed a significant increase after MCP in normal subjects, EH, and APA, but not in IHA. The incremental response of plasma Aldo. was largest in APA and smallest in IHA. The percentage increase in plasma Aldo. from the basal level was significantly attenuated in IHA, while no significant difference was seen among other groups. Although plasma PRL showed a significant increase in response to MCP, no difference of the change was seen among the groups. There was no significant change in plasma cortisol, renin, serum sodium, and serum potassium levels in response to MCP. In addition, the response of Aldo. to MCP was normalized in APA after unilateral adrenalectomy, while that of PRL did not change. These results indicate that the adrenal dopaminergic activity is enhanced in APA and attenuated in IHA and suggest an involvement of the dopaminergic system in the pathogenesis of IHA.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗

PubMed1995

Pathophysiological significance of plasma total renin and prorenin in patients with diabetes mellitus.

To seek the pathophysiologic significance of measuring the concentration of total renin instead of prorenin, we determined the plasma total renin concentration by immunoradiometric assay and correlated the results with various clinical features and laboratory parameters of diabetic complication in 108 patients with diabetes mellitus. The plasma prorenin concentration was estimated as the difference between the total and active renin concentrations. The plasma total renin and prorenin concentrations were high in patients with diabetes mellitus, in contrast to the active renin concentration which was slightly decreased. In addition, the plasma total renin and prorenin concentrations were higher in patients with diabetic complications than in patients without any complication. Multiple regression analysis showed that the presence of orthostatic hypotension, diabetic retinopathy, and proteinuria is significantly associated with the increased plasma total renin and prorenin concentrations. In addition, there was a significant positive correlation between the total renin and prorenin concentrations. These results suggest that both the plasma total renin concentration and the prorenin concentration are closely related to diabetic complications. Determination of the plasma total renin concentration by immunoradiometric assay as a substitute for prorenin could be a powerful tool in elucidating the mechanism for the increased plasma prorenin in diabetes mellitus.

Adult↗

PubMed1995

Effects of acute hyperinsulinemia on plasma atrial and brain natriuretic peptide concentrations.

Impaired renal sodium excretion and increased plasma atrial natriuretic peptide (ANP) levels have been reported in patients with hypertension associated with insulin resistance and hyperinsulinemia. To clarify the interrelationship between hyperinsulinemia and plasma natriuretic peptides, we investigated the effects of physiological and non-physiological hyperinsulinemia on the plasma ANP and brain natriuretic peptide (BNP) levels. Plasma immunoreactive insulin (IRI), ANP and BNP levels were determined by a euglycemic-hyperinsulinemic glucose clamp in 20 patients with non-insulin-dependent diabetes mellitus, by a glucose challenge test in 22 normal subjects and by an insulin challenge test in six normal subjects. Both in the glucose clamp and the glucose challenge test, plasma ANP showed a significant increase in association with increased plasma IRI and plasma volume. However, there was no significant correlation between the changes in plasma ANP levels and plasma IRI levels in view of the peak values and the area under the curve of their responses. In addition, the plasma ANP did not show any significant change despite the marked elevation of plasma IRI in the insulin challenge test. There was no significant change in plasma BNP under any of the hyperinsulinemic conditions. These findings provide in vivo evidence for the lack of a direct effect of acute hyperinsulinemia on natriuretic peptides, although the chronic effects of hyperinsulinemia remain to be elucidated.

Acute Disease↗

PubMed1995

Ganglioglioma in the basal ganglia totally resected by a trans-distal Sylvian approach.

A patient with a ganglioglioma in the basal ganglia is presented. An 18-year-old man presented with involuntary movement in his right hand and right homonymous hemianopsia. Computed tomography and magnetic resonance imaging revealed a cystic tumor with an enhancing nodule in the basal ganglia extending into the thalamus. The mass was totally resected by a trans-distal Sylvian approach and was histologically proven to be a ganglioglioma. This is a rare case of midline ganglioglioma in a patient who underwent gross total resection.

Adolescent↗

PubMed1995

Effect of exercise on endotoxin shock with special reference to changes in concentration of cytokines.

The effects of exercise on susceptibility to endotoxin shock and the serum levels of interleukin-1 (IL-1) and interleukin-6 (IL-6) were studied in mice primed with Propionibacterium acnes (P. acnes, 1.0 mg). Endotoxin shock was induced by injection of lipopolysaccharide (LPS, 0.2 mg) 7d after the priming injection of P. acnes. The exercise-loaded mice performed voluntary exercise for 120 min on a running-wheel and LPS was injected into the tail vein immediately after the end of exercise. Two of the nine animals in the exercised group survived, whereas all the mice in the control group died. The mean survival time after LPS injection in the exercised group (10.75 +/- 4.51 h) was significantly longer than that in the control group (3.3 +/- 1.34h). The serum concentrations of IL-1 (2,883 +/- 1,542 U/ml) and IL-6 (966 +/- 619 ng/ml) in the exercised group, sampled 2h after LPS challenge, were significantly lower than those in the control group (6,571 +/- 2,766 U/ml and 2,428 +/- 1,228 ng/ml, respectively). It is suggested that the exercise-induced inhibition of endotoxin shock may be caused, at least partly, by the decreased production of IL-1 and IL-6.

Animals↗

PubMed1995

Serial positron emission tomography imaging of changes in amino acid metabolism in low grade astrocytoma after radio- and chemotherapy-- Case report.

A 37-year-old male with mixed glioma was treated with combined radio- and chemotherapy. The amino acid metabolism of the tumor site and normal brain was followed by positron emission tomography using [11C]methionine ([11C]Met). The accumulation of [11C]Met in the tumor decreased during therapy and slightly increased 7 months after completion of the therapy, but then decreased markedly. However, computed tomography revealed no notable changes. The contralateral gray matter also showed a gradual decrease of [11C]Met accumulation. These findings indicate that reduction of amino acid metabolism in the tumor continues after radiochemotherapy although neuroimaging reveals no further morphological changes. Such therapy also has long-term effects on normal brain tissue.

Adult↗

PubMed1995

Surgical removal of giant basal ganglia arteriovenous malformations through the extended transsylvian approach following preoperative embolization--two case reports.

A 12-year-old boy and a 22-year-old male presented with sudden onset of consciousness disturbance with right-sided hemiparesis and aphasia due to massive intracerebral hemorrhage from giant striocapsular arteriovenous malformations (AVMs). Angiography revealed giant AVMs located at the left basal ganglia in both patients. Large frontotemporal craniotomies were performed following staged embolization of the feeding arteries. Through an extended transsylvian approach, the lesions were totally excised with confirmation using intraoperative digital subtraction angiography. The patients showed a transient postoperative worsening of symptoms, but recovered to their preoperative status at discharge. Motor functions of the right upper and lower extremities were graded 4/5 in both patients. These cases demonstrate that combined use of preoperative embolization and intraoperative angiography allows some giant deep AVMs to be resected with encouraging results.

Adult↗

PubMed1995

[Improved transportation for the elderly (II). The desire for and effects of continuing driving among car manufacturing retirees living in Kanagawa Prefecture].

In order to improve the adequacy and safety of the transportation for the elderly people, the effects of and the desire for continuing driving were analyzed. A questionnaire was sent to 500 car manufacturing retirees, male aged 60 years old and more, living in Kawagawa prefecture near Tokyo. Responses were obtained from 296 people (59.6%). Of these 196 were currently licensed and 149 still drove. Three quarters of the respondents drove for daily shopping and more than 50% drove for medical treatment, visiting friends and other purposes. The purposes for driving correlated with each other (p < 0.05; psi test) and 80% drove more than 3 days per week. One motivating factor for driving was to pick up family members or friends (48%) in addition to daily transportation means (93%), while 61% desired to continuing driving while making full use of the safety devices of the cars. Correspondence analysis showed that the role of driving correlated with a desire to utilize automobile safety devices. It is concluded that we should consider the needs of driving for the elderly, their satisfaction in driving or being driven by them, and should plan medical assessment, improvement in the traffic environment and social support, for example, arranging contacts between elderly driver and elderly with limited transportation options.

Aged↗

PubMed1995

[Interhemispheric differences of the middle latency auditory evoked magnetic fields revealed by a whole head magnetoencephalography system].

It is known that the auditory evoked N100m response appears faster in the contralateral hemisphere than in the ipsilateral hemisphere to the stimulated ear. For the middle latency response named P50m, however, there have been only few studies with controversial findings. In the present study, auditory evoked responses to the unilateral tone stimuli were measured in 36 right-handed normal subjects, using a helmet-shaped whole head magnetoencephalography system. In a total of 72 hemispheres of 36 subjects, P50m dipolar patterns were observed statistically (p > 0.02) frequently in the contralateral hemispheres (63.9%) compared to the ipsilateral hemispheres (43.0%). N100m dipolar patterns were observed over both left and right hemispheres either by left or right ear stimuli. Peak latency of the P50m was statistically (p < 0.02) shorter in the contralateral hemisphere (45.0 +/- 8.5ms, mean +/- s.d.) compared to the ipsilateral hemisphere (54.4 +/- 11.5ms). Peak latency of the N100m was also statistically (p < 0.001) shorter in the contralateral hemisphere. Moreover, when compared between contralateral responses, the left-ear stimulated right-hemispheric response (84.6 +/- 8.4) was statistically (p < 0.05) faster than the right-ear stimulated left-hemispheric response (89.3 +/- 10.2ms). These results indicate that contralateral auditory cortex dominates the ipsilateral cortex at the middle as well as the long latency components. Moreover, at least for pure-tone stimuli, right hemispheric dominance was indicated for the N100m responses. The whole-head MEG system is suitable to analyze small but significant interhemispheric difference of auditory function.

Adult↗

PubMed1995

[Ipsilateral coexistence of AVM and meningioma: a case report].

The authors encountered a rare case of sphenoidal ridge meningioma associated with an arteriovenous malformation in the same cerebral hemisphere. A 65-year-old female was admitted to our service because of headache. X-ray computed tomography (X-CT) and magnetic resonance image (MRI) disclosed a huge mass with peripheral edema, diagnosed as a sphenoidal ridge meningioma. An associated small mass was also noted in the right parahippocampal gyrus. This was confirmed by angiography as an arteriovenous malformation (AVM). During the waiting period for surgical treatment she had fallen into coma abruptly. Emergency X-CT revealed intracerebral and intraventricular hematomas. Both lesions were resected successfully in a one stage operation. Postoperative course was uneventful. In general, AVM located in the medial temporal lobe is difficult to approach. However, in this case, the resultant large cavity obtained after removal of meningioma afforded us easy access to the AVM.

Aged↗

PubMed1995

[Proton MR spectroscopy of the brain in patients with congenital myotonic dystrophy].

Volume selective proton MR spectroscopy (1H-MRS) of the brain was performed on a 1.5T magnet in five patients with congenital muscular dystrophy (CMyD), 46 healthy children, and one healthy adult. Peaks of N-acetylaspartate (NAA), choline (Cho) and creatine (Cr) were observed in both patients and control groups on 1H-MRS, but lactate was not observed. 1H-MRS revealed an increase in the ratio of NAA/Cho and NAA/Cr, and a decrease in Cho/Cr ratio with age in control subjects. In patients with CMyD, the values of NAA/Cho ratio did not increase with age. The values of NAA/Cr ratio decreased with age. The values of Cho/Cr ratio decreased with age in both patient and control groups. At age more than 4 years, the values of NAA/Cho and NAA/Cr ratios were lower in patients with CMyD than in controls. The values of Cho/Cr ratio did not differ between CMyD and controls. These results suggest that in patients with CMyD, there is an NAA decrease and a developmental disorder of neurons in the brain.

Adolescent↗

PubMed1995

[Surgical decompression for massive cerebellar infarction].

The authors report 10 patients with progressive neurological deterioration due to massive cerebellar infarctions. Computerized tomography scans confirmed obstructive hydrocephalus and brain stem compression. All 10 patients (seven men, three women; mean age, 59 years) were treated by external ventricular drainage and decompressive suboccipital craniectomy. After discharge from the hospital, they were followed up (23-101 months) and their functional independence was evaluated by the Barthel Index. The condition of three patients with brain-stem infarction had deteriorated despite decompressive surgery. Two of these died during the acute stage and one because severely disabled. The remaining seven patients showed neurological improvement during the postoperative period. Four patients with preoperative Japan Coma Scale of 100 returned to their previous jobs within the follow-up period and three patients with preoperative Japan Coma Scale of 200 required some assistance in daily activities. It is suggested that decompressive surgery may be beneficial for massive cerebellar infarction. The postoperative prognosis depends mainly on the presence or absence of coexisting brain-stem infarction. It is possible that, without brain-stem infarction, patients who remained in a "dependent" state may have recovered better if they had been operated on earlier.

Aged↗

PubMed1995

[Spontaneous rupture of the ureter caused by metastatic ureteric tumor: a case report].

Spontaneous rupture of the right upper ureter caused by metastatic ureteric tumor in an 80-year-old man is reported. He was admitted to our hospital with right lower abdominal pain. Ultrasonography showed mild right hydronephrosis and a low echogenicity mass under the right kidney. Drip infusion pyelography and abdominal computerized tomography showed extravasation of contrast medium around the right upper ureter. Retrograde pyelography was unsuccessful because of edema of the bladder wall. Right ureterocutaneostomy was performed under the diagnosis of spontaneous rupture of the right ureter. The right ureter was completely obstructed 3 cm below the point where it crossed the common iliac artery. At this site, the ureteric wall was hard, thickened, and adherent to the surrounding tissue. The lesion was a metastatic adenocarcinoma. The origin of the tumor could not be found, but pancreatic cancer was suspected on the basis of elevated CEA and PSTI levels. He died of peritonitis carcinomatosis at 8 months after surgery. Thirty three cases of spontaneous rupture of the ureter and 60 cases of metastatic ureteric tumor have been reported in Japan. However, our patient is the first reported case of spontaneous rupture of the ureter caused by a metastatic ureteric tumor in the Japanese literature.

Adenocarcinoma↗

PubMed1995

[99mTc-ECD dynamic SPECT in "luxury perfusion" of subacute stroke].

To evaluate the cerebral pharmacokinetics of 99mTc-ethyl cysteinate dimer (99mTc-ECD) at blood flow levels beyond the normal range, we investigated "luxury perfusion" in subacute stroke, ictal hyperperfusion in epilepsy and post-decompressive hyperemia in head trauma. All 7 patients showed a hyperactive area on SPECT studies using 99mTc-HM-PAO. 99mTc-ECD static image demonstrated a hyperactive area in both epilepsy and head trauma, and a hypoactive area in "luxury perfusion." On the dynamic SPECT of 99mTc-ECD in both epilepsy and head trauma, brain distribution of the tracer was determined within 2 min. postinjection and remained stable for up to 1 hour; however, "luxury perfusion" area showed a change from initial hyperactivity to late hypoactivity with the passage of time. The time activity curve in "luxury perfusion" area demonstrated a steep decrease of counts/pixel for up to 4-5 minutes postinjection, and a moderate decrease in the following phase. The early wash-out mechanism of 99mTc-ECD from "luxury perfusion" area can be described by a biexponential function including an initial steep decrease representing the rapid loss of the lipophilic complexes which were not metabolized in injured brain tissue.

Acute Disease↗

PubMed1995

Role of embolization in the management of arteriovenous malformations.

For the best management of AVMs, it is essential to achieve complete elimination of abnormal arteriovenous shunting. Classically, it was considered that surgical resection of the nidus was the only way to achieve this objective. With the significant advancement and introduction of new technology, the quality of the treatment using embolization and radiosurgery improved so rapidly that it is difficult to introduce all of these achievements. However, we should utilize these three modalities, depending on the patient's condition and the anatomic condition of the lesion. Furthermore, it is better to use less invasive methods, including embolization and gamma knife radiosurgery, than to use a treatment that requires craniotomy. One of the major drawbacks of embolization as a primary modality of treatment is the low rate of complete radioanatomic cure. We should further advance the embolization technique because it facilitiates any treatment that follows.

Cerebral Angiography↗

PubMed1994

Angiotensin converting enzyme inhibitor but not calcium blocker down-regulates gene expression of vascular natriuretic peptide receptor in hypertensive rats.

We have recently found that vascular natriuretic peptide (NP)-A receptor mRNA is upregulated in genetically hypertensive (SHR-SP/Izm) and deoxycorticosterone acetate (DOCA)-salt hypertensive rats. In the present study, we examined the effects of antihypertensive treatments on aortic NP-A receptor mRNA expression in these hypertensive rats using ribonuclease protection assay. Oral administration of an angiotensin converting enzyme inhibitor, derapril, but not a calcium channel blocker, manidipine, produced a significant decrease of the NP-A receptor mRNA level after 4 weeks, while both antihypertensive agents showed similar hypotensive effects. Plasma renin was high in SHR-SP/Izm and low in DOCA-salt rats. These results suggest that the vascular renin-angiotensin system rather than the blood pressure has an important role in the regulation of the vascular NP-A receptor.

Animals↗

PubMed1994

Expression, purification, and characterization of porcine leukocyte 12-lipoxygenase produced in the methylotrophic yeast, Pichia pastoris.

A cDNA coding for porcine leukocyte 12-lipoxygenase was expressed intracellularly in the methylotrophic yeast Pichia pastoris under the regulatory control of the alcohol oxidase promoter. The recombinant 12-lipoxygenase contained in the yeast cell lysate was soluble, displayed the catalytic properties of the native enzyme, and was recognized by antibodies prepared against native 12-lipoxygenase derived from porcine leukocytes. The catalytically active enzyme of the 100,000 x g supernatant obtained from the yeast lysate was readily purified by immunoaffinity chromatography to near homogeneity. Porcine leukocyte 12-lipoxygenase is the first arachidonic acid oxygenase to be expressed in yeast, an easy, inexpensive, and rapid method of expressing native and site-directed mutants of recombinant proteins.

Animals↗