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Biomedical subjects

N Yamada

Publications and source records attributed to N Yamada.

At least 181 records · Page 10Linked to original sources

[Evaluation of right ventricular function by intraoperative transesophageal echocardiography for patients with left ventricular dysfunction].

We evaluated right and left ventricular function by intraoperative transesophageal echocardiography for the patients with left ventricular dysfunction (left ventricular ejection fraction (LVEF) < or = 40) who underwent isolated coronary artery bypass grafting (CABG). We divided these patients into two groups; group 1 who had difficulty of weaning from cardiopulmonary bypass due to hypotension (n = 8) and group 2 who did not have any difficulty of it (n = 17). Basement characteristics (age, gender, history of myocardial infarction, congestive heart failure, LVEF, severity of the right coronary artery disease) of both groups were not different significantly. Intraoperative characteristics (the number of distal anastomoses, duration of aortic cross-clamp and cardiopulmonary bypass, and bypass to the right coronary artery) were also not different between two groups. However, mean duration of ICU stay and in-hospital mortality were significantly longer and higher in group 1 than group 2. On the other hand, right ventricular systolic function was severely impaired, particularly postoperatively, in group 1 compared with group 2. Right and left ventricular systolic function of group 2 was fairly improved postoperatively. These results may indicate that right ventricular dysfunction is a potent predictor of postoperative morbidity and mortality for the patients with left ventricular dysfunction who undergo isolated CABG.

Aged↗

[Limited upper sternotomy for minimally invasive aortic valve replacement].

The practice of minimally invasive valve surgery remains controversial. From May 1998, we began minimal invasive aortic valve replacement through the limited upper sternotomy. This technique is simple and provides and easy approach for the aortic valve. From May 1998 to Jan 2000, we performed 15 cases of aortic valve replacement with the limited upper sternotomy approach. All patients received valve replacement with prosthetic valve. We also described a simple and easy air evacuation system to avoid air embolism, a serious problem with a limited operative field. Mean aortic cross clamping time was 79 min, mean cardiopulmonary bypass time was 106 min, and mean operation time was 207 min. It did not take too much time compared with the conventional approach. Mean extubation time was 62 min and mean bleeding 12 hours after the operation was 96 ml. No patient required blood transfusions. All patients but one walked the very next day after the operation. We believe this new method brings not only cosmetic benefits, but also results in excellent post-operative course.

Adult↗

[Hepatic arterial infusion chemotherapy for unresectable liver metastasis of gastrointestinal cancers].

Thirty-two patients with colorectal cancer, eleven with gastric cancer and two with pancreatic cancer were treated by hepatic arterial infusion chemotherapy from March 1988 to December 1999. A single administration of 5-FU, MMC and epirubicin (FAM group), or intermittent continuous infusion of 5-FU 500 mg/2 h (5-FU continuous group) was used for each patient once a week. Overall survival rates were not significantly different between the gastric and colorectal cancer patients. In patients with colorectal cancer, there was a significant prolongation in overall survival for the response group. With gastric cancer, however, there was no significant difference. For both of the two patients with pancreatic cancer, although they were responsive to the therapy, there was no prolongation of survival. In conclusion, intermittent continuous infusion was more effective for the patients with colorectal cancer. In patients with gastric and pancreatic cancer, hepatic intra-arterial infusion could control the progression of liver metastasis.

Antineoplastic Combined Chemotherapy Protocols↗

[Expandable metallic stent for the treatment of left-sided colonic obstruction with malignant disease].

Recently, it was reported that an EMS (expandable metallic stent) was useful for treatment of colorectal obstruction. In our department, EMSs were used for seven patients with left-sided colonic obstruction with unresectable malignant disease. After these treatments with EMS, their symptoms were improved and they were able to intake food. Stomal formation was avoided except in one patient with severe soiling. In conclusion, EMS is thought to be useful for the improvement of quality of life in the patients with unresectable malignant colonic obstruction.

Adult↗

[Efficacy of axillary-axillary bypass grafting for the subclavian artery disease].

Axillary-axillary bypass procedure was performed in 5 patients (3: atherosclerosis, 1: rupture of aortic arch aneurysm, 1: trauma) with the total occlusion of the subclavian artery. All the operations were performed with 6 mm ringed expanded polytetrafluoroethylene under general anesthesia. Though several types of extrathoracic procedures such as carotid-subclavian bypass, subclavian-subclavian bypass and axillary-axillary bypass are introduced, the efficacy of axillary-axillary bypass procedure is greater ease of anatomic exposure with no concern of interfering with the carotid circulation. The type of bypass to be used in a given case will depend on the individual circumstances. We suggest that this procedure is minimally invasive as well as effective for subclavian artery occlusion depending on the case.

Adult↗

[Asymptomatic familial basal ganglia calcification with autosomal dominant inheritance: a family report].

We report here a pedigree of basal ganglia calcification with autosomal dominant inheritance. Following a traffic accident, the proband, a seven-year-old boy, was incidentally noted by cranial computed tomography to have calcification of the bilateral basal ganglia. Six affected members spanning three generations, aged from 5 to 57 years, also had calcification in various degree. None of them had clinical symptoms. There were neither abnormal data nor any characteristic physical symptoms associated with parathyroid disorders. There was no consanguinity. Both sexes were affected and the sex ratio was 0.5. Male-to-male transmission was documented. These findings suggested an autosomal dominant trait. The clinico-radiological findings in our pedigree were different from those of the previously reported cases of familial basal ganglia calcification, that infants were affected and that clinical symptoms were absent in elderly patients. These facts suggest our pedigree is a new type of familial basal ganglia calcification with autosomal dominant inheritance.

Basal Ganglia Diseases↗

Comparison of conservative and operative treatments of massive rotator cuff tears.

The results of conservative and operative treatment of massive rotator cuff tears were compared. All 9 men and 5 women who were treated conservatively (group I) had a Hamada Gpoup 4 arthrographic tear. The mean follow-up period was 4 years. The operative group (group II) was composed of 23 men and 3 women who had cuff tears of more than 5.0 cm in longest dimension. The mean age range at surgery was 62 years. Following anterior acromioplasty (n = 26), additional procedures included tenorrhaphy (n = 12), fascial grafting (n = 8), laterl transfer of the long head of the biceps brachii tendon (n = 2), muscle transfer of the teres minor (n = 3), muscle transfer of the supraspinatus (n = 1). The mean follow-up period was 4 years. The results were assessed using the Japanese Orthopaedic Association score. The JOA score was increased from 53.2 to 71.1 in group I, and from 58.8 to 85.9 in group II. More improvement in painrelief, muscle strength, and range of motion was obtained in group II than in group I. There was a significantly better final result in the patients without rupture of the tendon of the long head of the biceps brachii muscle.

Aged↗

Sterol regulatory element-binding protein-1 as a key transcription factor for nutritional induction of lipogenic enzyme genes.

To elucidate the physiological role of sterol regulatory element-binding protein-1 (SREBP-1), the hepatic mRNA levels of genes encoding various lipogenic enzymes were estimated in SREBP-1 gene knockout mice after a fasting-refeeding treatment, which is an established dietary manipulation for the induction of lipogenic enzymes. In the fasted state, the mRNA levels of all lipogenic enzymes were consistently low in both wild-type and SREBP-1(-/-) mice. However, the absence of SREBP-1 severely impaired the marked induction of hepatic mRNAs of fatty acid synthetic genes, such as acetyl-CoA carboxylase, fatty acid synthase, and stearoyl-CoA desaturase, that was observed upon refeeding in the wild-type mice. Furthermore, the refeeding responses of other lipogenic enzymes, glycerol-3-phosphate acyltransferase, ATP citrate lyase, malic enzyme, glucose-6-phosphate dehydrogenase, and S14 mRNAs, were completely abolished in SREBP-1(-/-) mice. In contrast, mRNA levels for cholesterol biosynthetic genes were elevated in the refed SREBP-1(-/-) livers accompanied by an increase in nuclear SREBP-2 protein. When fed a high carbohydrate diet for 14 days, the mRNA levels for these lipogenic enzymes were also strikingly lower in SREBP-1(-/-) mice than those in wild-type mice. These data demonstrate that SREBP-1 plays a crucial role in the induction of lipogenesis but not cholesterol biosynthesis in liver when excess energy by carbohydrates is consumed.

Acetyl-CoA Carboxylase↗

A crucial role of sterol regulatory element-binding protein-1 in the regulation of lipogenic gene expression by polyunsaturated fatty acids.

Dietary polyunsaturated fatty acids (PUFA) are negative regulators of hepatic lipogenesis that exert their effects primarily at the level of transcription. Sterol regulatory element-binding proteins (SREBPs) are transcription factors responsible for the regulation of cholesterol, fatty acid, and triglyceride synthesis. In particular, SREBP-1 is known to play a crucial role in the regulation of lipogenic gene expression in the liver. To explore the possible involvement of SREBP-1 in the suppression of hepatic lipogenesis by PUFA, we challenged wild-type mice and transgenic mice overexpressing a mature form of SREBP-1 in the liver with dietary PUFA. In the liver of wild-type mice, dietary PUFA drastically decreased the mature, cleaved form of SREBP-1 protein in the nucleus, whereas the precursor, uncleaved form in the membranes was not suppressed. The decreases in mature SREBP-1 paralleled those in mRNAs for lipogenic enzymes such as fatty acid synthase and acetyl-CoA carboxylase. In the transgenic mice, dietary PUFA did not reduce the amount of transgenic SREBP-1 protein, excluding the possibility that PUFA accelerated the degradation of mature SREBP-1. The resulting sustained expression of mature SREBP-1 almost completely canceled the suppression of lipogenic gene expression by PUFA in the SREBP-1 transgenic mice. These results demonstrate that the suppressive effect of PUFA on lipogenic enzyme genes in the liver is caused by a decrease in the mature form of SREBP-1 protein, which is presumably due to the reduced cleavage of SREBP-1 precursor protein.

Animal Feed↗

Generation of mature dendritic cells from a CD14+ cell line (XS52) by IL-4, TNF-alpha, IL-1 beta, and agonistic anti-CD40 monoclonal antibody.

We established a model system to generate mature dendritic cells (DC) from a GM-CSF-dependent cell line, XS52, which had been isolated from the epidermis of newborn BALB/c mice. Screening of various soluble factors revealed that IL-4 induces phenotypic maturation of XS52 (as evaluated by enhanced expression of class II, CD40, CD80, CD86, CD11c, and loss of expression of CD14) in a time-dependent manner. The addition of TNF-alpha, IL-1 beta, and agonistic anti-CD40 mAb further enhanced expression of these maturation markers. Consistent with their phenotypic maturation, these cells (termed XS-DC) exhibited potent Ag-presenting capacity to both naive and primed T cells. In addition, injection of hapten-conjugated XS-DC induced contact hypersensitivity in vivo, suggesting their potential as tools for vaccination. Expression of CD14 by the starting cell population, the requirement for GM-CSF and IL-4, and the relatively long culture period are the common characteristics shared between our cells and human monocyte-derived DC, whose analogues in mice have not been identified. Because large numbers of skin-associated mature DC devoid of other cell lineages are easily obtained, this model system may facilitate the study of molecular events associated with maturation of DC and the use of DC for immunization.

Adjuvants, Immunologic↗

Embryonic lethality and defective neural tube closure in mice lacking squalene synthase.

Squalene synthase (SS) catalyzes the reductive head-to-head condensation of two molecules of farnesyl diphosphate to form squalene, the first specific intermediate in the cholesterol biosynthetic pathway. We used gene targeting to knock out the mouse SS gene. The mice heterozygous for the mutation (SS+/-) were apparently normal. SS+/- mice showed 60% reduction in the hepatic mRNA levels of SS compared with SS+/+ mice. Consistently, the SS enzymatic activities were reduced by 50% in the liver and testis. Nevertheless, the hepatic cholesterol synthesis was not different between SS+/- and SS+/+ mice, and plasma lipoprotein profiles were not different irrespective of the presence of the low density lipoprotein receptor, indicating that SS is not a rate-limiting enzyme in the cholesterol biosynthetic pathway. The mice homozygous for the disrupted SS gene (SS-/-) were embryonic lethal around midgestation. E9.5-10.5 SS-/- embryos exhibited severe growth retardation and defective neural tube closure. The lethal phenotype was not rescued by supplementing the dams either with dietary squalene or cholesterol. We speculate that cholesterol is required for the development, particularly of the nervous system, and that the chorioallantoic circulatory system is not mature enough to supply the rapidly growing embryos with maternal cholesterol at this developmental stage.

Animals↗

Alleic variants of human melatonin 1a receptor: function and prevalence in subjects with circadian rhythm sleep disorders.

The human melatonin 1a (hMella) receptor gene was screened for mutations using genomic DNA samples from patients with circadian rhythm sleep disorders and control subjects by single strand conformational polymorphism analysis (SSCP). We found seven mutations, two of which predict amino acid changes R54W and A157V, respectively. The prevalence of the R54W variant and that of the A157V variant were several times more common in non-24-h sleep-wake syndrome subjects than among control subjects, although the incidence was not significant in our study group. When expressed in COS-7 cells, the R54W mutant receptor exhibited significantly reduced B(max) and slightly enhanced affinity (reduced K(d)) compared to the wild type receptor, while the A157V variant receptor showed similar binding characteristics to the wild type. The identification of variants in the hMella receptor will provide a useful tool for analyzing genetic predisposition toward various diseases related to melatonin function and to clarify the physiological role of melatonin receptors in humans.

Alleles↗

Improvement of impaired myocardial vasodilatation due to diffuse coronary atherosclerosis in hypercholesterolemics after lipid-lowering therapy.

BACKGROUND: Diminished myocardial vasodilatation (MVD) in hypercholesterolemics without overt coronary stenosis has been reported. However, whether the diminished MVD of angiographically normal coronary arteries in hypercholesterolemics can be reversed after lipid-lowering therapy is not known. METHODS AND RESULTS: A total of 27 hypercholesterolemics and 16 age-matched controls were studied. All patients had >1 normal coronary artery, and those segments that were perfused by anatomically normal coronary arteries were studied. Myocardial blood flow (MBF) was measured during dipyridamole loading and at baseline using positron emission tomography and 13N-ammonia, after which MVD was calculated before and after lipid-lowering therapy. Total cholesterol was significantly higher in hypercholesterolemics (263+/-33.8) than in controls (195+/-16.6), and it normalized after lipid-lowering therapy (197+/-19.9). Baseline MBF (ml. min-1. 100 g-1) was comparable among hypercholesterolemics (both before and after therapy) and controls. MBF during dipyridamole loading was significantly lower in hypercholesterolemics before therapy (189+/-75.4) than in controls (299+/-162, P<0.01). However, MBF during dipyridamole loading significantly increased after therapy (226+/-84.7; P<0.01). MVD significantly improved after therapy in hypercholesterolemics (2.77+/-1.35 after treatment [P<0.05] versus 2. 02+/-0.68 before treatment [P<0.01]), but it remained significantly higher in controls (3.69+/-1.13, P<0.01). There was a significant relationship between the percent change of total cholesterol and the percent change of MVD before and after lipid-lowering therapy (r=-0. 61, P<0.05). CONCLUSIONS: Diminished MVD of anatomically normal coronary arteries in hypercholesterolemics can be reversed after lipid-lowering therapy.

Aged↗

Elevated neuropeptide Y and corticotropin-releasing factor in the brain of a novel epileptic mutant rat: Noda epileptic rat.

Noda epileptic rat (NER) is a new epileptic rat strain, which was developed by inbreeding rats with spontaneous tonic-clonic seizures in a stock of Crj:Wistar. In the present study, possible changes of two neuropeptides, neuropeptide Y (NPY) and corticotropin-releasing factor (CRF), in the brains of NER were investigated. Increased contents of immunoreactive (IR) NPY were found in the striatum and amygdala of 8-week NERs with partial seizure, while these changes extended to the limbic region including hippocampus in 16-week NERs with fully developed generalized tonic-clonic seizure. IR-CRF were elevated only in the entorhinal and pyriform cortex of both 8-week and 16-week NERs. Generalized tonic-clonic seizure in NERs induced a transient increase of NPY mRNA in the granular layer of dentate gyrus. These results suggest that NPY metabolism in the limbic brain contributes to the seizure susceptibility in this model of epilepsy.

Animals↗