Biomedical subjects

N Kitamura

Publications and source records attributed to N Kitamura.

At least 307 records · Page 17Linked to original sources

PubMed1993

Spontaneous diabetes mellitus in young cattle: histologic, immunohistochemical, and electron microscopic studies of the islets of Langerhans.

Pathomorphologic studies were carried out on three cases of bovine diabetes mellitus with clinical signs of polydipsia, polyuria, severe emaciation, glycosuria, persistent hyperglycemia, and decreased glucose tolerance. At necropsy, two animals had atrophy of the pancreas, whereas other visceral organs, including the endocrine organs, showed no significant changes. Microscopically, there was atrophy and reduced numbers of pancreatic islets accompanied by interlobular and interacinar fibrosis and compensatory enlargement of some remaining islets. Lymphocytes were observed commonly around and within atrophic islets and occasionally around and within enlarged islets. Vacuolar degeneration with occasional accumulation of glycogen granules was observed in the beta-cells of these enlarged islets. Immunohistochemical studies of atrophic islets demonstrated complete loss of beta-cells or only a few small beta-cells. There also was a corresponding decrease in the number of cells that stained with anti-glucagon (alpha-cells) or anti-somatostatin (delta-cells) antibodies. The vacuolated cells in the enlarged islets stained strongly with anti-insulin antibody (beta-cells). Ultrastructurally, the majority of cells in the atrophic islets had reduced cytoplasmic volume and few secretory granules, features consistent with alpha-cells. In contrast, enlarged islets that had prominent immunohistochemical staining for insulin (beta-cells) consisted of beta-cells with cytosolic edema, mitochondrial swelling, dilated smooth endoplasmic reticulum, and reduced numbers of or degranulated secretory granules. These pathomorphologic features found in cattle are similar to those found in juvenile-onset insulin-dependent diabetes mellitus in human beings and suggest autoimmune involvement in diabetes.

Animals↗

PubMed1993

Left ventricular rupture following mitral valve replacement.

During a 10-year period, we have encountered 6 patients (mean age, 61.2 years) with left ventricular rupture following mitral valve replacement, with an overall incidence of 1.8 percent. Four patients had early rupture, one had delayed rupture, and one had late rupture with a false aneurysm formation. Among four patients with early rupture, there were two patients with external repair by using a large ventricular patch and two patients with internal and the external repair by removing the prosthetic valve and patching both the inside and outside of the ventricle. In a patient with delayed rupture, bleeding from an epicardial hematoma was recognized along the atrioventricular groove in the intensive care unit. It was possible to control bleeding by packing the gauze, hemostatic cellulose [Surgical], and fibrin glue. Late rupture was recognized as a false aneurysm; however, there were no clinical symptoms. All patients survived the surgery, but two patients with early rupture subsequently died. One of these died of renal failure and the other died of multiple organ failure. The sites of rupture in all patients were in accordance with type 1 rupture (Treasure's classification); however, an autopsy review demonstrated the initial laceration in one case was recognized in the membranous septum 5 mm below the mitral ring and extended to the posterior atrioventricular groove. These findings suggest that the injury in the anterior mitral annulus could lead to type 1 rupture, although in the posterior mitral annulus more commonly. Since 1987, we have preserved the posterior leaflet with attached chordae when the mitral valve was fragile and myxomatous. As a result, no instances of left ventricular rupture were encountered.

Aged↗

PubMed1993

Heterogeneity of motilin-immunoreactive cells in the duodenum and pyloric region of several avian species.

Immunohistochemical characterizations of motilin-immunoreactive cells were examined in gastric and duodenal mucosae of nine species of birds from seven orders using five different region-specific motilin antisera. Motilin-immunoreactive cells appeared as open-type cells in the mucosal epithelium and showed varying immunoreactivities to antisera used in all the birds examined except for the cormorant and penguin, which did not show any kinds of immunoreactivity to motilin. Motilin-immunoreactive cells of the emu duodenum were detected by all the motilin-antisera used. The present results suggest that there is a wide range of heterogeneity between motilin molecules among avian species, or perhaps alternatively the existence of a family of motilin-like peptide. Furthermore, the present results should prove useful for a molecular biological study on the evolution of avian motilin.

Animals↗

PubMed1993

Substance P-immunoreactive neurons of the bovine forestomach mucosa: their presumptive role in a sensory mechanism.

Substance P-immunoreactive nerve fibers and cell bodies were examined in the forestomach mucosa of the calf and cow pretreated with colchicine, using thick (100 microns) floating sections. Intraepithelial nerve fibers were identified, appearing only rarely in the rumen and reticulum, and completely absent from the omasum. Nerve fibers were observed in the lamina propria of all the regions of the forestomach examined. A few thin nerve fibers were seen in the core of the ruminal papillae of the calf, whereas in the cow they appeared very coarse in nature. Flocculent and complicated nerve fiber networks were seen in the connective tissue of the reticular papillae. Mucosal nerve fibers formed a peculiar glomerulus-like architecture in the omasal papillae of the calf, while in the cow, the nerve fibers were largely restricted in distribution to the vicinity of the epithelium within the connective tissue pegs. Immunoreactive nerve cell bodies were found in the ruminal atrium, the dorsal sac and the ventral sac of the rumen of the calf and in the reticulum of both the calf and cow. Some of these neurons exhibited processes that appeared to course toward the papillae. In total, substance P-immunoreactive nerve fibers and cell bodies were more abundant in the calf than in the cow. These distributions demonstrate that the neural circuitry of the bovine forestomach contains substance P immunoreactivity in the mucosa as well as in the muscle layer, pointing to its possible importance in the regulation of the forestomach function. Substance P-immunoreactive nerve fibers were numerous in the reticular papillae of the calf and cow and in the omasal papillae of the calf. The positive fibers at these localities may act as mucosal receptors.

Aging↗

PubMed1993

An immunohistochemical survey of peptide-containing nerves in the copulatory apparatus of several male birds.

Distribution of peptide-containing nerves in male copulatory apparatus as well as rectal and cloacal ganglia were examined immunohistochemically in cock, guinea fowl, duck and muscovy duck. Neurofilament protein-immunoreactive nerves were also examined to investigate general distribution of nerves. Substance P (SP)-, vasoactive intestinal polypeptide (VIP)-, calcitonin gene-related peptide (CGRP)-, and neuropeptide Y (NPY)-immunoreactive (IR) nerves were detected in all four species of birds whereas leucine enkephalin (LENK)-IR nerves were detected only in duck and muscovy duck. In the rectal and cloacal ganglia, peptide-IR nerves were detected in varying degrees of abundance. Most noticeable distribution was found in the vascular body, where SP-IR nerve fibres were more abundant in duck and muscovy duck, VIP-IR fibres in muscovy duck and CGRP-IR fibres in duck, than in other regions and other species, respectively. A few peptide-IR nerve fibres were detected in other cloacal regions, although a peculiar pattern in distribution unique to a certain region could be not found. The present results suggest that the peptide-containing nerves participate in the regulation of tumescence, erection and detumescence of male copulatory apparatus of birds and their regulatory mechanisms are different depending on the species.

Animals↗

PubMed1993

The cell dissociation and motility triggered by scatter factor/hepatocyte growth factor are mediated through the cytoplasmic domain of the c-Met receptor.

Scatter factor (SF), which dissociates epithelial cell colonies into individual cells and stimulates the migration of epithelial cells, is identical to hepatocyte growth factor (HGF), a mitogen for melanocytes, endothelial cells and epithelial cells, including hepatocytes. It was previously shown by cDNA transfection that the mitogenic effect of SF/HGF is mediated by activation of the tyrosine phosphorylation of the c-Met receptor (the c-met proto-oncogene product). In this study, we constructed a cDNA encoding a chimeric receptor composed of the extracellular domain of the epidermal growth factor (EGF) receptor and the transmembrane and cytoplasmic domains of the c-Met receptor. We transfected the cDNA into the B16-F1 mouse melanoma cell line to investigate whether the cell dissociation and motility were mediated through this chimeric receptor following ligand stimulation. The chimeric receptor cDNA was expressed in the transfected cells and the protein product was transported to the cell surface in the correct transmembrane orientation. EGF treatment of the chimeric receptor-expressing cells markedly enhanced tyrosine phosphorylation of the chimeric receptor and led to scattered morphology and enhanced motility. This scattered morphology was inhibited by a tyrosine kinase inhibitor. Based on these results, we concluded that the cell dissociation and motility triggered by SF/HGF were mediated through the cytoplasmic domain of the c-Met receptor by activation of its tyrosine kinase. Thus, it is likely that the different biological effects of SF/HGF are mediated by different intracellular signal cascades.

Amino Acid Sequence↗

PubMed1993

An immunohistochemical study on the gastrointestinal endocrine cells of three honeyeaters: singing honeyeater (Meliphaga virescens), spiny-cheeked honeyeater (Acanthogenys rufogularis) and brown honeyeater (Lichmera indistincta).

The gastrointestinal endocrine cells of the singing honeyeater (Meliphaga virescens), spiny-cheeked honeyeater (Acanthogenys rufogularis) and brown honeyeater (Lichmera indistincta) were studied immunohistochemically with special reference to their degree of dependency upon nectar. The nine types of immunoreactive endocrine cells were detected in their gastrointestinal mucosa. Coexistence of motilin and serotonin in the same cells was confirmed in the pyloric region. In the duodenum and jejunum, a few peptide tyrosin tyrosin (PYY)-immunoreactive cells were detected. The clear difference in the distribution and frequency of the gastrointestinal endocrine cells among three types of honeyeaters, which differ in the degree of dependency upon the nectar, could not be confirmed. However, some differences were found that serotonin-, somatostatin- and gastrin-releasing peptide (GRP)-immunoreactive cells in the gizzard, gastrin-immunoreactive cells in the duodenum and jejunum, enteroglucagon-immunoreactive cells in the caeca and in the colon, and pancreatic glucagon-immunoreactive cells in the ileum of brown honeyeaters were more numerous (p < 0.05) than other two species.

Animals↗

PubMed1993

Six years' experience with the Omnicarbon valve prosthesis.

Between January 1985 and March 1990, isolated Omnicarbon valve replacement operations were performed on 90 patients aged 25-72 years. There were 53 aortic valve replacements (AVR) and 37 mitral valve replacements (MVR). The cumulative follow-up was 320 patient-years, with a mean(s.d.) follow-up of 3.7(1.4) years. There were three operative and hospital deaths (3.3%) resulting from retrograde aortic dissection during cardiopulmonary bypass, postoperative renal failure and postoperative mediastinitis. Seven patients died during the late postoperative period, four from valve-related causes. Two of these patients died from prosthetic valve endocarditis, and the others died from thromboembolism and valve thrombosis. The mean(s.d.) actuarial survival rate at 6 years was 86.2(4.3)% (98.8(0.8)% for AVR, 82.1(4.8)% for MVR). The mean(s.d.) actuarial survival rate of freedom from all valve-related mortality at 6 years was 93.5(2.6)% (100% for AVR, 88.1(2.9)% for MVR). There were two thromboembolic events (one mesenteric artery thrombosis and one valve thrombosis). The standardized incidence of thromboembolism was 0.63% per patient-year. Prosthetic valve endocarditis occurred in three patients (0.94% per patient-year). One patient (0.31% per patient-year) was found to have a paravalvular leak resulting from aortitis syndrome. The mean(s.d.) actuarial rate of freedom from all valve-related complications at 6 years was 89.2(2.0)% (98.6(1.0)% for AVR, 86.4(2.2)% for MVR). There were no instances of anticoagulant-related haemorrhage, valve-related haemolysis, or structural failure. Results of a follow-up period of 6 years indicated that good clinical results and a low incidence of valve-related complications can be demonstrated with the Omnicarbon valve.

Adult↗

PubMed1993

Second messenger systems in brains of patients with Parkinson's or Huntington's disease.

Alterations in protein kinase C (PKC) and myo-inositol 1,4,5-trisphosphate (IP3) receptors were studied in the autopsied human striata from 21 patients with Parkinson's disease (PD) (Yahr III, IV, and V), 8 patients with Huntington's disease (HD), and 23 age-matched and postmortem time-matched nonneurological controls. The concentrations of PKC and IP3 receptors were determined using [3H]4 beta-phorbol 12,13-dibutyrate (PDBu) and [3H]IP3 as respective ligands. Both the specific [3H]-PDBu and [3H]IP3 bindings were significantly reduced in the striata of Yahr V patients with dementia (PDD) and in that of HD patients, as compared to findings in the controls. These bindings were unchanged when all the PD patients without dementia, Yahr (III plus IV) patients, or Yahr V patients without dementia were compared with evidence from the controls. Immunoquantification of four PKC subspecies (alpha, beta I, beta II, and gamma) in the HD putamen revealed a selective reduction in the beta II-PKC immunoreactions. These results are supported by immunohistochemical findings in the rat brain that beta II-PKC is expressed in the striatal gabaergic efferent pathway, while the alpha-PKC is present in the nigrostriatal dopaminergic neurons. The neurochemical pathophysiology of PD differs between patients with and without dementia.

Aged↗

PubMed1993

[Mechanical dilation of the internal thoracic artery graft by using balloon catheter].

We evaluated the free flow of the internal thoracic artery grafts (ITA) which were dilated with a balloon catheter. Further, we examined the postoperative angiographic findings and histology of the ITAs by scanning electron microscopy. In 25 patients with internal thoracic artery grafting, the artery was dilated with a balloon catheter (Fogarty IMAG kit) that was withdrawn at tensions of less than 30 gm. The mean free flow rate of the left ITAs (LITAs) increased from 64.2 ml/min to 101.9 ml/min by injection of papaverine to ITAs (p < 0.05). The mean free flow rate of the balloon dilated LITAs were 160.8 ml/min which was significantly higher when compared with that of control and papaverine (p < 0.01, p < 0.01). The mean free flow rate of the balloon dilated right ITAs (RITAs) showed 183.2 ml/min, it was significantly higher (p < 0.01, p < 0.05) compared with that of control (78.4 ml/min) and papaverine (129.2 ml/min). Irregularity was documented in 16% of the ITAs in spite of the great patency rate (100%) from the postoperative angiogram. Using scanning electron microscopy, endothelial cell borders were well demarcated in the proximal portion of the dilated ITA. However, the distal portion of the endothelium displayed gradual destruction. Although mechanical dilation of the ITA graft by balloon calibration is very effective in increasing the free flow rate of ITA, we should be prepared for the intimal damage of the ITA graft.

Adult↗

PubMed1993

A new procedure for aortic valve repair.

A new technique is presented for aortic valve repair. This procedure involves shaving the surface of rheumatic aortic valves using a high-speed electric rasp. It is safer and more expeditious to shave the concave shaped aortic cusp at the base, and then shave the body of the cusp along the flexion stress line. In a patient treated using this procedure, aortic valve regurgitation decreased and the aortic valve gradient almost disappeared.

Aortic Valve↗

PubMed1993

Optimal shape of prosthesis for tricuspid valve replacement.

To develop an optimal prosthesis for use in the tricuspid valve, we determined the change in cardiac performance associated with the change in shape of the anulus of the tricuspid valve using a metal ring of variable flat ratio (defined as the long/short axis). In experiment I in an isolated autoperfusion model with six dogs, the left ventricular stroke work under a constant left atrial pressure of 7 mm Hg were, in grams per beat per minute, 11.88 +/- 0.52 with a flat ratio of 1.0, 11.88 +/- 0.70 with a flat ratio of 1.3, 16.23 +/- 0.61 with a flat ratio of 1.6, and 11.22 +/- 0.38 with a flat ratio of 2.3 (mean +/- standard error of the mean). The volume was significantly higher with a flat ratio of 1.6 than with the other ratios (p < 0.05). In experiment II with six dogs in vivo, the blood flow of the pulmonary trunk artery was 0.57 +/- 0.03 L/min with a flat ratio of 1.0, 0.66 +/- 0.03 L/min with a flat ratio of 1.6, and 0.58 +/- 0.03 L/min with a flat ratio of 2.3; the flow was significantly larger with a ratio of 1.6 than with the other ratios (p < 0.05). Right ventriculography was performed in five dogs. The percentage of radial shortening of the apex close to the acute margin was 19.4% +/- 3.1% with a flat ratio of 1.0 and 49.2% +/- 5.1% with a flat ratio of 1.6 (p < 0.05). In conclusion, the best hemodynamic results were obtained with a flat ratio of 1.6, which showed more advantageous hemodynamics than do the ratios of conventional circular prostheses.

Animals↗

PubMed1993

[Comparative study in graft patency of individual and sequential grafting as coronary bypass].

We analyzed the graft patency rates of the individual saphenous vein graft (SVG) group and those of the sequential SVG group. In the individual SVG group, 184 SVGs were anastomosed to 184 coronary arteries. Twenty-six SVGs were used sequentially to 52 coronary arteries in the sequential group. The patency rates of all the SVGs in both groups showed no significant differences. The patency of left anterior descending (LAD), left circumflex (LCX), right coronary artery (RCA) and diagonal branch (Dx) was 96%, 67%, 90% and 63% respectively in the individual SVG group. In the sequential SVG group, the patency rates of LCX (95%) were much higher than those (67%) of the individual SVG group (p < 0.05). The patency rates of side-to-side anastomoses (SSAs) were 92% and those of the distal end-to-side anastomoses (ESAs) were 96% in the sequential SVG group. There were no significant differences between SSAs and ESAs. While, the patency rates of SSAs-Dx, ESAs-Dx, SSAs-LCX and ESAs-LCX were 89%, 100%, 100%, and 93% respectively in the sequential SVG group. There were no significant differences between two groups. These results showed that the sequential grafting is useful and effective for LCX coronary arteries in coronary artery bypass surgery. In conclusion, it seems that in LCX coronary arteries, the patency rates obtained by the sequential SVG technique are better than those obtained by using the individual SVG technique.

Coronary Artery Bypass↗

PubMed1993

[Clinical preeminence of single aortic cross-clamping for proximal anastomoses in coronary artery bypass surgery].

We evaluated the preeminence of the construction of proximal anastomoses during single aortic cross-clamping periods in coronary artery bypass surgery. Twenty-six patients were divided into two groups; single aortic cross-clamping (SAX) group: 13 patients, partial aortic clamping (PAC) group: 13 patients. In this study, these two groups were compared in terms of aortic cross-clamping time (AXT), total extracorporeal circulation (ECC) time (TECCT), ECC weaning time (WT), amount of cardioplegic solution, total levels of serum CPK and CPK-MB, and graft patency. The results were analyzed by ANOVA and chi-square test. AXT was longer in the SAX group compared with the PAC group (78.2 +/- 5 versus 63.2 +/- 4 min; p < 0.05). TECCT (120.4 +/- 6 versus 109 +/- 5 min) and WT (37.4 +/- 2 versus 41 +/- 2 min) were not significant between the two groups. The total amount of cardioplegic solution was greater in the SAX group compared with the PAC group (1100 +/- 60 versus 927 +/- 43 ml; p < 0.05). The levels of serum CPK and CPK-MB were a little lower in the SAX group, but there were no significant differences between the SAX group and the PCA group. The graft patency of both two groups were excellent. From these results, SAX is not critical in the routine of coronary artery bypass surgery. Clinically, the SAX technique allows us to select more suitable areas of the ascending aorta for placement of all the proximal grafts if the ascending aorta is short.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗

PubMed1993

Gene expression and regulation of HGF-SF.

Molecular cloning and characterization of cDNAs and genomic DNA for human HGF-SF revealed the expression pattern of the gene. Alternative use of splicing sites and processing/polyadenylation sites generates multiple mRNAs for human HGF-SF in a variety of tissues and cell lines. This alternative mRNA production may be regulated in a tissue-specific manner. Full-length HGF-SF is encoded by the 6.3 kb or 3.1 kb mRNA. A variant form of HGF-SF is encoded by the 1.5 kb mRNA which is generated by alternative splicing accompanied by the utilization of an alternative processing/polyadenylation site in an extra exon. The variant form consists of an N-terminal sequence and the first two kringles and acts as an antagonist of HGF-SF mitogenic activity. HGF-SF with a deletion of 5 amino acids in the first kringle is produced from an alternatively spliced mRNA. The deletion induces the change in the heparin-binding property of the protein. Analysis of responses of the HGF-SF mRNA during liver regeneration revealed that the HGF-SF gene is activated. The level of mRNA markedly increases in the rat liver, spleen and lung after administration of hepatotoxins. Characteristic regulatory elements, an IL6 response element and an NF-IL6 binding element, are present proximal to the major transcription initiation site in the human HGF-SF gene. These elements may be involved in the activation of the gene after liver injury. The potential autocrine role of HGF-SF in the acquisition of altered phenotypes was determined by introduction of the gene into target cells for HGF-SF. Autocrine production of the factor induces changes in cell properties from parental types to those obtained by the addition of exogenous factor.

Alternative Splicing↗

PubMed1993

[Surgical treatment of cardiac cachexia with mitral valve disease: the effect of preoperative IVH and left atrial plication on postoperative respiratory condition].

Twenty-four patients with cardiac cachexia associated with mitral valve disease were evaluated from the point of postoperative respiratory management. Our previous study suggested that preoperative intravenous hyperalimentation (IVH) had just a effect on postoperative respiratory management, but another study suggested that left atrial plication (LAP) for giant left atrium might improve the postoperative respiratory function. Therefore, four groups could be identified: (1) IVH group (17 patients), (2) No-IVH group (7 patients), (3) LAP group (6 patients), (4) No-LAP group (18 patients). The hospital mortality was 18% in IVH group and was not related to the postoperative respiratory distress. On the contrary, the mortality in No-IVH group was 57%, related to the postoperative respiratory distress. The mortality of LAP group was 67%, and was related to the respiratory distress except one patient. In No-LAP group which had undertaken preoperative IVH, the mortality was 17%. As a result, preoperative IVH therapy may consider to be a favorite procedure in order to get the good postoperative respiratory condition, but LAP itself would be suspicious for this purpose.

Adult↗

PubMed1993

[Scatter factor and cell motility].

Cell dispersion and motility are thought to be important steps in the invasion of tumor cells. The molecular mechanisms responsible for the induction of cell dispersion and motility remain unclear. Several factors affecting cell motility have been discovered. Among them, scatter factor (SF), a mesenchymal cell-derived protein, dissociates epithelial cell colonies into individual cells and stimulates the migration of epithelial cells. Purified SF promotes the invasiveness into collagen matrices of a number of human carcinoma cell lines, suggesting that SF is involved in the invasion of tumor cells. Recently, SF has been found to be identical to hepatocyte growth factor. Moreover, the c-met proto-oncogene product (the c-met protein) possessing a tyrosine kinase domain was identified as a receptor for SF. Three possible mechanisms have been postulated in which a tumor cell might increase its invasive potential through enhanced motility via SF and its receptor. First, in a cell already expressing the c-met protein, an unexpressed SF gene might be activated, leading to synthesis and secretion of the factor which could then initiate active motility in an autocrine fashion. Second, the tumor cell expressing the c-met protein may release a factor that affects surrounding mesenchymal cells, promotes synthesis and release of SF. The tumor cell would be stimulated in a paracrine fashion. Finally, the tumor cell may be exposed to SF already released by surrounding cells but may not be able to respond because it is partially or completely deficient in the c-met protein. Induction and increased expression of the c-met gene would result in the invasive phenotype of the tumor cell. Studies on these possible mechanisms will be required to elucidate the involvement of SF in the invasion of tumor cells.

Cell Movement↗

PubMed1993

[Prosthetic valve endocarditis after double valve replacement].

This is a report of a patient who underwent re-AVR due to prosthetic valve endocarditis after double valve replacement (MVR, AVR). A 54-year-old female was admitted to other hospital on April 14, 1990, because of high fever, progressive anemia, and cardiomegaly. The patient was hospitalized to our department urgently with the diagnosis of prosthetic valve endocarditis. Arterial blood culture grew methicillin-resistant Staphylococcus epidermidis. Echocardiography showed a vegetation at the disc of the mechanical valve in the mitral position, but we could not find any vegetation or thrombus there at the reoperation, and the aortic mechanical valve seemed to be intact. Signs of inflammation continued to be positive after reoperation. On the 33rd hospital day, a diastolic murmur was heard, and emergency cardiac catheterization was done. Detachment of the prosthetic aortic valve and rupture of the sinus of Valsalva due to mycotic aneurysm, and the dissection of the aorta had occurred. We performed re-AVR and replacement of the ascending aorta. The patient died of multiple organ failure following drug-induced hepatic failure. It is suggestive that we missed the prosthetic aortic valve endocarditis during the reoperation. Our thoughts and introspections on the echocardiographic diagnosis of the prosthetic valve endocarditis after double valve replacement were discussed.

Aneurysm, Infected↗