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Biomedical subjects

Y Naka

Publications and source records attributed to Y Naka.

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

Study of efficacies of leukocyte-depleted terminal blood cardioplegia in 24-hour preserved hearts.

To evaluate the effect of leukocyte-depleted terminal blood cardioplegia on prolonged preservation, 41 canine hearts were stored in modified Collins' solution and transplanted heterotopically. Hearts were transplanted soon after harvesting in group 1 and after 24-hour preservation in groups 2, 3, and 4. Blood cardioplegia was applied just before aortic unclamping in groups 3 and 4; group 3 received simple blood cardioplegia and group 4 received leukocyte-depleted cardioplegia. The percentage of the preload recruitable stroke work and diastolic compliance after transplantation compared with the preharvesting value in group 4 did not differ from those in group 1, but the percentage of the preload recruitable stroke work in groups 2 and 3 was significantly lower than that in groups 1 and 4. The percentage of diastolic compliance in groups 2 and 3 was significantly higher than that in groups 1 and 4. Coronary blood flow 40 minutes after aortic unclamping in group 4 did not differ from that in group 1, but was significantly higher than the blood flows in groups 2 and 3. Significant production of malondialdehyde was detected during terminal blood cardioplegia and 10 minutes after aortic unclamping in groups 2 and 3, but never in groups 1 and 4. After leukocyte-depleted terminal cardioplegia, the myocardial adenosine triphosphate content increased to the preharvesting value in group 4. Our results suggest that leukocyte-depleted terminal blood cardioplegia may be effective in replenishing the energy-depleted myocardium and reducing reperfusion injury, resulting in adequate cardiac function.

Adenosine Triphosphate↗
PubMed1994

Regeneration of norepinephrine-containing fibers in occipital cortex of adult cats.

Regeneration of norepinephrine (NE)-containing nerve fibers in occipital cortex of adult cats was studied using morphological and biochemical methods. Initially, degeneration of cortical NE fibers was induced by direct infusion of 6-hydroxydopamine (6-OHDA) for a week. Cortical reinnervation by NE fibers continuously proceeded throughout 52 weeks, the longest survival period studied, after stopping 6-OHDA infusion. The rate of the reinnervation was slower in mature cortex than that obtained earlier in immature cortex. The present results indicate that the regenerative ability of the central NE neurons is universal, not limited to the immature brain. It is implied that the central NE neurons are equipped with a transmitter-specific repair mechanism throughout life.

Animals↗
PubMed1994

Effect of long-term administration of probucol on triglyceride turnover in rats.

BACKGROUND: Our previous observation revealed that probucol, a well known cholesterol-lowering drug, can improve impaired catabolism of plasma triglyceride in streptozotocin-diabetic rats without reducing plasma glucose. The present study was conducted using Triton WR1339 and endogenously radiolabeled lipoproteins in order to examine the mechanisms whereby the drug can stimulate triglyceride removal from the circulation in rats independent of glucose metabolism. METHODS: The short- and long-term effects of probucol on triglyceride turnover were examined in rats. Male Wistar rats received a diet containing probucol (1%) for 2 weeks and 4 months. Triglyceride turnover was estimated in rats using Triton WR1339. RESULTS: After 2 weeks of probucol administration, triglyceride and cholesterol concentrations in plasma and in the very-low-density lipoprotein (VLDL) fraction were suppressed slightly but significantly in the probucol-administered rats compared with standard chow-fed control rats. However, triglyceride secretion rates were similar in the two groups. Probucol-administered rats showed markedly suppressed triglyceride concentration in plasma and the VLDL fraction compared with chow-fed control rats after 4 months of administration. However, triglyceride secretion rate was significantly increased in rats given probucol. The radioisotope experiment revealed that probucol-administered rats can remove VLDLs (lipoproteins either from probucol-administered or control rats) from their system faster than normal rats and that probucol-containing VLDL can be removed from the circulation of both groups of rats more rapidly than normal VLDL. Therefore, probucol-administered rats as well as probucol-containing VLDL (lipoprotein from probucol-administered rats) are responsible for accelerated catabolism of VLDL-triglyceride. CONCLUSION: No significant differences in the lipid composition of newly-secreted VLDL particles between control rats and those given probucol were noted after Triton injection. The precise mechanism behind increased triglyceride secretion rate in rats after long-term administration of probucol is not known. However, we concluded from the present data that long-term administration of probucol results in markedly accelerated VLDL-triglyceride turnover without affecting lipid composition of newly secreted VLDL particles in normal rats.

Animals↗
PubMed1994

Cardiac preservation is enhanced in a heterotopic rat transplant model by supplementing the nitric oxide pathway.

Nitric oxide (NO) is a novel biologic messenger with diverse effects but its role in organ transplantation remains poorly understood. Using a porphyrinic microsensor, the first direct measurements of coronary vascular and endocardial NO production were made. NO was measured directly in the effluent of preserved, heterotopically transplanted rat hearts stimulated with L-arginine and bradykinin; NO concentrations fell from 2.1 +/- 0.4 microM for freshly explanted hearts to 0.7 +/- 0.2 and 0.2 +/- 0.08 microM for hearts preserved for 19 and 38 h, respectively. NO levels were increased by SOD, suggesting a role for superoxide-mediated destruction of NO. Consistent with these data, addition of the NO donor nitroglycerin (NTG) to a balanced salt preservation solution enhanced graft survival in a time- and dose-dependent manner, with 92% of hearts supplemented with NTG surviving 12 h of preservation versus only 17% in its absence. NTG similarly enhanced preservation of hearts stored in University of Wisconsin solution, the clinical standard for preservation. Other stimulators of the NO pathway, including nitroprusside, L-arginine, or 8-bromoguanosine 3',5' monophosphate, also enhanced graft survival, whereas the competitive NO synthase antagonist NG-monomethyl-L-arginine was associated with poor preservation. Likely mechanisms whereby supplementation of the NO pathway enhanced preservation included increased blood flow to the reperfused graft and decreased graft leukostasis. NO was also measured in endothelial cells subjected to hypoxia/reoxygenation and detected based on its ability to inhibit thrombin-mediated platelet aggregation and serotonin release. NO became undetectable in endothelial cells exposed to hypoxia followed by reoxygenation and was restored to normoxic levels on addition of SOD. These studies suggest that the NO pathway fails during preservation/transplantation because of formation of oxygen free radicals during reperfusion, which quench available NO. Augmentation of NO/cGMP-dependent mechanisms enhances vascular function after ischemia and reperfusion and provides a new strategy for transplantation of vascular organs.

Amino Acid Oxidoreductases↗
PubMed1993

Solitary squamous cell papilloma of the trachea.

We report a case of solitary squamous cell papilloma of the trachea and review 55 other previously reported cases. A 69-year-old man was admitted to our hospital with hemoptysis. Bronchoscopy demonstrated a papillomatous tumor diagnosed as a squamous cell papilloma. A circumferential resection of the trachea with end-to-end anastomosis was carried out. The patient's postoperative course was uneventful. From the review, there seems to be no considerable difference in the prognoses between the endoscopically and surgically managed groups. The following indications for surgical management of solitary tracheobronchial papilloma are proposed: (1) wide-based tumor, (2) poorly visualized tumor by endoscopy, (3) suspicion of malignant tumor, and (4) patients not suitable for long-term follow-up.

Actuarial Analysis↗
PubMed1993

Effect of a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor on triglyceride kinetics in chronically streptozotocin-diabetic rats.

The effect of simvastatin (MK-733, Banyu, Tokyo, Japan), a new inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase on triglyceride kinetics, was studied in chronically streptozocin-diabetic rats. Diabetic rats, in whom diabetes was induced by a single intravenous injection of streptozotocin (40 mg/kg body weight) 2 months before the experiment, had significantly higher plasma glucose, triglyceride, and cholesterol levels compared with nondiabetic control rats, but triglyceride secretion rate was not increased. Both triglyceride secretion rate and plasma triglyceride level were significantly suppressed under nonfasting conditions in diabetic rats fed a (0.1%) simvastatin-containing diet for 10 days. After an overnight fast, their triglyceride secretion rate was not suppressed by this diet. However, their plasma triglyceride level was significantly (50%) suppressed, suggesting improved triglyceride removal from the circulation. In diabetic rats, the newly secreted triglyceride-rich lipoprotein particles were significantly cholesterol-enriched, but simvastatin had no effect on their lipid composition. These results suggest that the hypertriglyceridemia seen in chronically diabetic rats is mainly due to a triglyceride-removal defect, and that simvastatin reduces plasma triglyceride levels in these rats both by stimulating triglyceride removal and by reducing its entry into the circulation.

Animals↗
PubMed1993

Acute subdural hematoma associated with vacuolated meningioma--case report.

A 67-year-old male presented with a left temporal convexity vacuolated meningioma associated with acute subdural hematoma manifesting as sudden headache, nausea, and vomiting without neurological deficit. Magnetic resonance imaging disclosed an extra-axial mass as mixed low- and high-signal intensities and a crescent high-intensity area in the left convexity. Histological examination diagnosed meningotheliomatous meningioma with vacuolated components and hemorrhagic foci. The tumor and hematoma were removed without postoperative complications.

Aged↗
PubMed1993

Hypertriglyceridemia in nephrotic rats is due to a clearance defect of plasma triglyceride: overproduction of triglyceride-rich lipoprotein is not an obligatory factor.

This study was conducted to determine whether overproduction of triglyceride-rich lipoprotein is an obligatory factor for experimental hypertriglyceridemia in nephrotic rats. Nephrosis was induced in male Wistar rats by administration of 150 mg/kg puromycin aminonucleoside. Nephrotic rats had slightly increased triglyceride secretion rate (TGSR) estimated using Triton WR1339 (0.53 +/- 0.05 vs. 0.45 +/- 0.04 mg/min, P < 0.05 vs. control rats) and marked hypertriglyceridemia (330.4 +/- 78.6 mg/dl). Rats made diabetic by 40 mg/kg streptozotocin were normotriglyceridemic (66.3 +/- 12.1 mg/dl) but had suppressed TGSR (0.33 +/- 0.09 mg/min). Experimental nephrosis was induced in diabetic rats. Their TGSR remained suppressed (0.35 +/- 0.06 mg/min) but they had marked hypertriglyceridemia (296.6 +/- 72.4 mg/dl) suggesting further impairment of triglyceride removal from the circulation in diabetic rats caused by nephrosis. Endogenously radiolabeled very low density lipoprotein (VLDL)-triglyceride from donor rats was reinjected into normal recipient rats. [3H]VLDL from the experimental groups (the rats with nephrosis, diabetes with nephrosis, and diabetes alone) were more slowly cleared by normal rats than VLDL from normal rats. These results suggest that circulating insulin is essential for increased triglyceride secretion in experimental nephrosis and that nephrotic hypertriglyceridemia can be induced only by a triglyceride removal defect. Therefore, hypersecretion of triglyceride-rich lipoprotein is not an obligatory factor for nephrotic hypertriglyceridemia.

Animals↗
PubMed1993

[A case of retrocaval ureter treated in childhood].

A case of retrocaval ureter in a 10-year-old boy is reported. His chief complaint was asymptomatic total macrohematuria. Physical examination and all laboratory findings were within normal limits, but drip infusion pyelography revealed a right hydronephrosis with "S shaped" ureter. The diagnosis was confirmed by enhanced CT scan. After follow-up for 1 year and a half, right uretero -ureterostomy was performed because the severity of the hydronephrosis had increased. We review 25 cases of retrocaval ureter in childhood reported in the Japanese literature and compare the clinical characteristics between infant cases and adult cases.

Child↗
PubMed1993

[A case of cholesterol granuloma with hematoma of tunica albuginea].

A case of cholesterol granuloma with hematoma of the tunica albuginea is reported. A 52-year-old man complained of a painless mass in the left scrotum. The mass was 50 x 25 x 30 mm in size. An operation was performed. Macroscopically the mass originated from the tunica albuginea and was a cystic lesion with a thick fibrous capsule. The cystic lesion was filled with an old hematoma. An extirpation was performed. Microscopically, the sections showed fibrogranulomatous tissue containing innumerable cholesterol clefts and numerous foreign body giant cells. The histological diagnosis was cholesterol granuloma with hematoma. This is the sixth case of cholesterol granuloma of the external genitalia, and is the first case of cholesterol granuloma with hematoma of the tunica albuginea in the literature.

Cholesterol↗
PubMed1992

Keratin profiles in normal/hyperplastic prostates and prostate carcinoma.

Immunoreactivities in 25 cases of prostatic adenocarcinoma and 10 normal/hyperplastic prostates were investigated in methacarn-fixed, paraffin-embedded serial sections using a panel of nine anti-keratin monoclonal antibodies (mAbs); 34 beta E12, CK8.12, 312C8-1, CK4.62, RPN1165, RPN1162, 35 beta H11, CK5, M20, and one of anti-actin mAb, HHF35. In normal/hyperplastic prostates, RPN1162, 35 beta H11, CK5 and M20 stained luminal cells without staining basal cells, and 34 beta E12, CK8.12 and 312C8-1 stained basal cells but not luminal cells. Other mAbs, CK4.62 and RPN1165, stained basal cells as well as luminal cells. All of the mAbs labelling luminal cells stained cancer cells with variable frequencies in a manner unrelated to the grade of tumour differentiation. Of the prostate cancer cases 92% were scored positive with M20, 84% with 35 beta H11, 80% with CK5, 68% with CK4.62, 60% with RPN1165 and 4% with RPN1162. However, basal cell-specific keratins labelled with 34 beta E12, CK8.12 and 312C8-1 were totally negative in the cancer cells. HHF35 showed no labelling in normal, hyperplastic or neoplastic epithelial cells of the prostate. Our findings indicate that the major part of the cells of prostatic adenocarcinomas have keratin phenotypes similar to luminal cells but not basal cells, and that no myoepithelial differentiation can be detected in epithelial cell of the prostate. Thus, mAbs for keratins facilitate the identification of epithelial cell phenotypes in normal, benign and malignant conditions of the prostate.

Adolescent↗
PubMed1992

Effect of long-term insulin deficiency and insulin treatment on the composition of triglyceride-rich lipoproteins and triglyceride turnover in rats.

The effect of long-term (4 months) insulin deficiency on triglyceride turnover was examined using Triton WR1339 in rats. Triglyceride secretion rate was estimated in rats 2 weeks and 4 months after induction of diabetes with 40 mg/kg of streptozotocin. By the second week diabetic rats showed prominent hyperglycemia and the plasma insulin level was very low. In spite of a lower triglyceride secretion rate compared to non-diabetic control rats, diabetic rats showed normotriglyceridemia. Thus, the estimated fractional catabolic rate for plasma triglyceride was decreased in the diabetic rats of 2 weeks duration. By the fourth month diabetic rats still showed a suppressed triglyceride secretion rate but plasma triglyceride was markedly higher than in the non-diabetic control rats. Therefore, their estimated fractional catabolic rate for plasma triglyceride was severely suppressed. They also showed hyperglycemia and hypercholesterolemia. The triglyceride-rich lipoprotein particles obtained after Triton injection in long-term diabetic rats were significantly cholesterol-enriched and triglyceride-depleted compared to control rats. These changes were already present in 2-week diabetic rats but the magnitude was significantly smaller that those in long-term diabetic rats. All of these abnormalities (including triglyceride turnover and the particle composition) were almost normalized by 2 weeks of insulin treatment (6 units/day). Thus, it was concluded from the present data that duration of insulin deficiency is an important determinant of triglyceride removal rate from the circulation in rats. Further modification of lipid composition of triglyceride-rich lipoprotein particles by long-term insulin-deficiency could be one of the reasons for this removal defect.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Myocardial energy metabolism in asphyxiated canine hearts preserved for 24 hours.

Myocardial energy metabolism in asphyxiated cadaver hearts preserved in UW solution (UWS; group 1, n = 6) or modified Collins' solution (MCS; group 2, n = 6) was compared with that in cardioplegic arrested hearts immersed in ice-cold MCS with (group 3, n = 6) or without myoprotective drugs (group 4, n = 5). All hearts were stored for 24 hr. The hearts in groups 1 and 2 were pretreated with prostacyclin, verapamil, and propranolol; asphyxiated for 10 min, reversed by coronary perfusion with warm blood cardioplegia (WBCP); perfused with ice-cold crystalloid cardioplegia for 2 hr; excised and immersed in cold storage solution for 22 hr; and perfused again with WBCP before reperfusion. ATP contents were measured in biopsy specimens by HPLC. Myocardial ATP level decreased significantly from 23.7 +/- 1.7 to 15.9 +/- 2.5 mumol/g dry wt. (P less than 0.0001) by asphyxia, but recovered to within normal limits by WBCP in group 1. The ATP level again decreased to 15.8 +/- 2.4 mumol/g dry wt. during 24-hr storage, but finally rose to 22.4 +/- 3.5 mumol/g dry wt. by terminal WBCP. The ATP metabolism in group 2 was similar to that in group 1. The ATP content in group 4 was significantly lower than that in other groups (P less than 0.01) after 24-hr preservation. The study shows that damage to cadaver hearts can be reversed and the hearts maintained satisfactorily viable for 24 hr.

Adenosine Triphosphate↗
PubMed1992

[Benefits and problems of home infusion therapy].

A survey was performed to clarify the benefits and problems of home infusion therapy because 8 years had passed since this type of treatment was officially approved in Japan. Questionnaires were sent to hemophiliacs and the physicians in charge of hemophiliacs in the Kyushu district. The main results obtained from analysis of responses concerning 197 patients were as follows. 1) Out of 197, 140 patients were on home therapy programs. 2) The number of bleeding episodes was increased in 6.8%, decreased in 51.1% and unchanged in 42.1% of patients after the start of home infusion therapy programs. 3) The severity of bleeding symptoms was reduced in 92.9% of patients after the start of these programs. 4) After the start of home infusion therapy programs, the amount of blood products administered increased in 24.4%, decreased in 20.6% and was unchanged in 55.0%. 5) Complications such as abdominal pain, headache, ulticaria, itching, shivering, fever and discomfort were reported from 19 hemophiliacs. Only one of them visited the hospital due to severe abdominal pain which appeared immediately after home infusion of blood product. 6) It was indicated that better education or re-education of home infusion therapy is necessary for hemophiliacs and/or their families who are on home infusion therapy programs, because half of them had not received proper education concerning home infusion.

Blood Substitutes↗
PubMed1991

Lecithin-cholesterol acyltransferase (LCAT) deficiency with a missense mutation in exon 6 of the LCAT gene.

The plasma enzyme, human lecithin-cholesterol acyltransferase (LCAT) is responsible for the majority of cholesterol ester formation in human plasma and is a key enzyme of the reverse transport of cholesterol from peripheral tissue to the liver. We sequenced genomic DNA of the LCAT gene from a Japanese male patient who was clinically and biochemically diagnosed as a familial LCAT deficiency. Analysis of all exons and exon-intron boundaries revealed only a single G to A transition within the sixth exon of both allele of the gene, leading to the substitution of methionine for isoleucinle at residue 293 of the mature enzyme. This mutation creates a new hexanucleotide recognition site for the restriction endonuclease Ndel. Familial study of Ndel digestion of the genomic DNA and determination of plasma LCAT activity established that the patient and his sister whose plasma LCAT activity were extremely reduced were homozygous and his children whose plasma LCAT activity were about half of normal controls were heterozygous for this mutation.

Base Sequence↗
PubMed1991

[Acute subdural empyema due to peptostreptococcus].

A very rare case of acute subdural empyema due to peptostreptococcus was reported. A 11-year-old-girl was admitted to our hospital with high grade fever, unconsciousness and rt hemiparesis. CT scans showed the mass effect caused by the subdural empyema over the left frontotemporal region. Subdural empyema was evacuated by the craniotomy. Peptostreptococcus was found in the pus obtained during the operation. However, CT scans 10 days after the operation revealed another subdural empyema in the left frontal base and interhemispheric fissure, which was removed again by the craniotomy using coronal incision 14 days after the first operation. Frontal sinusitis was also demonstrated by CT scan. Killian's operation to the frontal sinusitis was performed by otorhinolaryngologists at the same time. Six weeks after the second operation, she was discharged without any neurological deficits. Peptostreptococcus is one of the indigenous microflora of the oral cavity, skin, gastrointestinal tract and genitourinary system and may be a causative microorganism in every type of human infection due to its abnormal localization. There is a controversy concerning surgical management subdural empyema. Both the burr hole drainage of pus and the craniotomy are advocated. Associated otorhinologic lesions must not be overlooked. Otorhinologic consultation should immediately be obtained so that the drainage of an infected paranasal or mastoid sinus can be performed at the time of craniotomy. This is critical to prevent the recurrence of the subdural empyema from further extension of the extracranial disease.

Acute Disease↗