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Biomedical subjects

M Nishida

Publications and source records attributed to M Nishida.

At least 325 records · Page 18Linked to original sources

In vitro and in vivo changes of serotype in Pseudomonas aeruginosa isolates by anti-pseudomonal drugs.

The present study was designed to clarify whether anti-pseudomonal drugs affected in vitro and in vivo changes in serotypes of Pseudomonas aeruginosa isolates. Forty-two isolates of P. aeruginosa belonging to different serotype groups were each incubated in Mueller-Hinton broth including piperacillin, cefsulodin, ceftazidime, imipenem, gentamicin or norfloxacin at 1 approximately 4 MICs at 35 degrees C for 20 hours. The bacterial cells in the media were serotyped after the incubation. In each experiment with these six drugs, serotypes of 4 (9.5%) to 8 (19.0%) of the 42 isolates changed to other different groups. There was no relationship between the serotypes of the variants formed with the anti-pseudomonal drugs and kinds of the drugs. In the case of P. aeruginosa TA-2 isolate, the different concentrations (1/2 MIC and 2 x MIC) of cefsulodin induced the distinct changes in serotypes such as the poly-agglutinable (M, G) and non-typable groups, respectively. The time course for the formation of the variant cells was investigated during the incubation of P. aeruginosa TA-2 isolate in the presence of cefsulodin, respectively. In this case, the variant cells appeared 6 hours after incubation and continued to grow together with the intact cells. On the other hand, the variant cells with anti-pseudomonal drugs (cefsulodin, imipenem and gentamicin) were also formed in the model infections in mice. The present results indicated that the co-existence of colonies with different serotypes in some isolates of P. aeruginosa was partially due to the alternation of serotypes with anti-pseudomonal drugs given to patients with infection.

Animals↗

[Treatment of stage Ia ovarian cancer].

Ninety-six patients with primary ovarian cancer were treated at Tsukuba University Hospital between 1984 and 1992. For all of these patients except stage IV, surgical treatment including pelvic and paraaortic lymphadenectomy was employed to confirm the clinical stage exactly. Re-staging laparotomy was performed in cases with an incomplete initial operation. In thirty cases the primary tumors were truly confined to the unilateral ovary (stage Ia). In six patients, though the tumor appeared to be confined to the unilateral ovary macroscopically at the time of the operation, the stage changed to Ic in one case, IIa in one case and IIIc in 4 cases as found by postoperative confirmation. The most common tumor in stage Ia was mucinous cystadenocarcinoma. In 23 patients with stage Ia, histological grading could be obtained. Twenty-one cases were low potential malignancy or grade 1, whereas grade 3 was found in only one case. None, except one case diagnosed as stage Ia, has had a recurrence in spite of the absence of adjunct therapy, but one patient with grade 3 endometrioid carcinoma died of the disease 10 months after staging laparotomy. In conclusion, even though the tumor appears to be confined to one ovary, a staging laparotomy should be conducted in all patients. When the tumor is proved to be limited to only one ovary and is also histologically confirmed to be less than grade 3, it is considered that no further treatment is necessary.

Antineoplastic Combined Chemotherapy Protocols↗

[Evaluation of Matas test by CBF studies, angiographic cross-filling and stump pressure in CEA patients].

Temporary and/or permanent occlusion of carotid artery is one of the most important strategy in the surgical treatment for cervical vascular and paraclinoid lesions. Cerebral ischemia produced by this procedure should be preoperatively grasped for the safety of the surgeries. Matas test has been widely applied to estimate the collateral blood flow at the main artery occlusion by observing only clinical features. In this study, we measured CBF and common carotid artery stump pressure (CCA stump P) in contrast to angiographic cross-filling in 43 carotid endarterectomy (CEA) patients to quantitatively evaluate Matas test. The patients were manually occluded the CCA on the affected side and clinically observed for at least 10 minutes. CCA stump P and cross-filling were evaluated in all patients and CBF measurements were carried out in the patients who clinically tolerated Matas test. CBF studies were performed by single photon emission CT with Xe-133 inhalation method and CBF values were obtained in the middle cerebral artery territory before and during Matas test. CCA stump P was measured during carotid angiography by manual occlusion of the proximal site of the CCA. Cross-filling was evaluated with the contralateral carotid angiography during the manual occlusion of the affected CCA. CBF changes in Matas test were classified into the following four patterns; bilateral mild decreases in CBF, unilateral severe decrease in CBF, unilateral mild decrease in CBF and no decrease in CBF. The frequency of bilateral mild decreases in CBF, unilateral severe decrease in CBF, unilateral mild decrease in CBF and no decrease in CBF were 8, 10, 14, 7 of 43 patients, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Ischemia↗

[Near infrared spectrophotometric monitoring for cerebral ischemia during the occlusion of the internal carotid artery at CEA].

Near infrared spectrophotometry provides noninvasively real-time information on cerebral oxygenation and cerebral blood volume. Using this method of spectrophotometry we investigated the adequacy of collateral circulation during cross-clamping of the internal carotid artery in patients who underwent carotid endarterectomy. In 15 patients, oxy-hemoglobin, deoxyhemoglobin and total hemoglobin were monitored continuously by near infrared spectrophotometry at the ipsilateral frontal area on the operated side. Changes in these parameters following temporary cross-clamping of the internal carotid artery were evaluated. The stump pressure of the internal carotid artery was measured in every patient. Only the maximum decrease in oxy-hemoglobin during cross-clamping of the internal carotid artery correlated significantly with the stump pressure of the internal carotid artery. Changes in oxy-hemoglobin during cross-clamping of the internal carotid artery demonstrated three patterns; no change or minimally decreased (4 patients), decrease with recovery (4 patients), and decrease without recovery (7 patients). The stump pressure of the internal carotid artery in patients who had no recovery of their decreased oxy-Hb was significantly lower than that in any other pattern (p < 0.01, Mann-Whitney U analysis). Patients who experience decrease in oxy-Hb without recovery following cross-clamping of their internal carotid artery may have poor collateral circulation and therefore may develop cerebral ischemia.

Aged↗

[Ruptured distal anterior cerebral artery aneurysms presenting with acute subdural hematoma: report of two cases].

Two cases of ruptured distal anterior cerebral-artery aneurysms presenting with acute subdural hematoma are reported. Case 1 was a 55-year-old male, who showed abrupt disturbance of consciousness. An emergency CT revealed acute subdural hematoma at the right parietal convexity and interhemispheric fissure with moderate midline shift. There was no evidence of subarachnoid hemorrhage. Right carotid angiography showed an aneurysm at the right distal anterior cerebral artery. An emergency external decompression was performed and the aneurysm was clipped successfully through the interhemispheric fissure. In the operative field, subarachnoid hemorrhage could not been seen, and the patient had uneventful recovery. Case 2 was a 66-year-old female, who complained of severe headache. She deteriorated rapidly and become comatous with development of anisocoria. An emergency CT revealed acute subdural hematoma on the bilateral parietal convexities and interhemispheric fissure with severe midline shift. There was no evidence of subarachnoid hemorrhage. Carotid angiography showed right distal anterior cerebral artery aneurysm. An emergency external decompression was performed, then the aneurysm was clipped successfully. She recovered with disorientation and hemiparesis. Ruptured distal anterior cerebral artery aneurysms presenting with acute subdural hematoma without subarachnoid hemorrhage are rare. It is suggested that CT scans and history of patients are most important but an emergency angiography was prerequisite for correct diagnosis. Surgical treatment should be the best management in such cases.

Acute Disease↗

[Clinicopathoradiological studies in 15 cases of megadolichobasilar anomaly].

We clinicopathoradiologically assessed 15 angiographically diagnosed megadolichobasilar anomalies. Nine of the patients were male and 6 were female; their average age was 61 years. Eleven patients presented with cerebral ischemic attacks, other two complained of trigeminal neuralgia and the remaining two suffered severe headaches. Twelve of the patients had severe hypertension. Vertebral angiography revealed marked elongation of the basilar artery with severe tortuousity and dilatation. The average distance from the dorsum sellae to the basilar artery bifurcation on the lateral view was 24.7 mm, and the average maximum diameter of the basilar artery was 8.6 mm. Aneurysmal dilatation of the basilar artery was also observed in four cases. In 14 of the 15 patients CT scans revealed characteristic findings, such as tubular high density mass with evident contrast enhancement extending from the ventral medulla to the interpeduncular cistern. The outcome was extremely poor, with five deaths and four patients with severe dementia. In the two autopsy cases, enlarged internal lumens could be observed despite severe atheroscrelotic changes, such as intimal thickening by atheromas.

Aged↗

[Evaluation of angiographic delayed vasospasm due to ruptured aneurysm in comparison with cerebral circulation time measured by IA-DSA].

Delayed vasospasm due to ruptured aneurysm has been basically evaluated by angiographic changes in contrast to clinical features such as delayed ischemic neurological deficits (DIND). However, the discrepancies between angiographic and clinical findings have been pointed out. In this study, angiographic changes and cerebral circulation time in ruptured aneurysms were simultaneously investigated with IA-DSA. Thirty-two patients, who had ruptured aneurysms at the anterior circle of Willis and neck clippings at the acute stage, were investigated. Carotid angiogram was performed with IA-DSA on the 7-13th day after the attack. Angiographic changes were evaluated by Fischer's classification and circulation time was calculated in the following way. A time-density curve was obtained at the two ROI's; the C3-C4 portion and the rolandic vein. Circulation time was defined by the difference between the time showing peak optical density at the carotid and the venous portion. The control value of this circulation time obtained from 20 cases with non-rupture aneurysm and epilepsy was 3.4 sec (53 year old) on the average. X-ray CT scan examination was performed at the same time and clinical features were observed everyday. Angiographically, 3 cases were free from vasospasm, 18 cases were found to present slight to moderate vasospasm, and 11 cases showed severe vasospasm. Circulation time in patients with no spasm was 3.6 seconds, in patients with slight to moderate vasospasm it was 4.3 seconds and in patients with severe vasospasm it was 6.8 seconds. Ten patients showing cerebral infarction on CT scans demonstrated significantly long circulation time, 7.0 second on the average.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Reconstruction of the hepatic vein to the prosthetic inferior vena cava in right extended hemihepatectomy with ex situ procedure.

BACKGROUND: Ex situ procedure permits complete resection of a tumor involving the confluence of the three main hepatic veins, which is difficult when conventional technique is used. METHODS: We report treatment of a patient with intrahepatic cholangiocellular carcinoma involving this confluence of the three main hepatic veins and the retrohepatic inferior vena cava (IVC) by using right extended hemihepatectomy and resection of the retrohepatic IVC with ex situ procedure. Reconstruction of the left hepatic vein required anastomosis of the left hepatic vein and a polytetrafluoroethylene (PTFE) replacement for the IVC. To our knowledge this is the first report of reconstruction of the hepatic vein by use of a PTFE prosthesis. RESULTS: Anastomosis of the left hepatic vein to the PTFE graft was successfully performed during extracorporeal liver operation. The patient has had no recurrence during 8 months since the operation. Neither torsion nor obstruction of the hepatic vein and the graft has been observed. CONCLUSIONS: Reconstruction of main hepatic veins and the PTFE graft as the replacement of the IVC under extracorporeal liver operation may be useful in improving the cure rate and resection rate for liver cancer that is unresectable by the conventional technique.

Anastomosis, Surgical↗

ADP modifies the function of the glucose transporter: studies with reconstituted liposomes.

Modification of function of the glucose transporter by nucleotides was studied by using liposomes reconstituted with the human erythrocyte glucose transporter. ADP enclosed in the liposomes inhibited the uptake of D-glucose and nicotinamide in a dose-dependent manner, but other enclosed nucleotides (ATP, AMP, CDP, GDP, UDP) showed no effect on the uptake of both. Only intraliposomal ADP was effective, and extra-liposomal ADP was not, under our experimental conditions. Intraliposomal ADP did not change Km, but decreased Vmax to approximately one-third of control for uptake of both D-glucose and nicotinamide. However, the binding and the affinity of cytochalasin B to the reconstituted liposomes were not affected by intraliposomal ADP. The uptake of uridine was not changed in the presence of ADP, indicating that the nucleoside transporter co-existing in the liposomal membranes is not regulated by ADP. Human erythrocytes whose intracellular ATP was decreased by Ca2+ ionophore A23187 also showed decreased uptake of 2-deoxy-D-glucose and nicotinamide. This phenomenon was very similar to that found in the liposomes. These findings suggest the possibility that the function of the glucose transporter is directly and negatively modified by an increased concentration of intracellular ADP.

Adenosine Diphosphate↗

Mechanism of phosphate adsorption to a three-dimensional structure of boehmite in the presence of bovine serum albumin.

A new microcrystalline boehmite (tentatively named PT-A) was synthesized as an efficient phosphate adsorbent to replace aluminum hydroxide gel. The characteristic structure of PT-A was examined by nitrogen adsorption/desorption, X-ray diffraction, deviation microscopy, and scanning electron microscopy to establish a pore structural model of PT-A. With this model structure, the details of the mechanism of interaction between PT-A and phosphate in the presence of bovine serum albumin (BSA) are discussed. PT-A is a spherical particle with a diameter of approximately 100 microns and a porous surface structure, and its inside is packed with boehmite microcrystals (crystallite size, 2 nm). PT-A has three types of pores in its structure: a micropore with a narrow size-distribution, a mesopore with a broad size-distribution, and a macropore (radii of pores are 0.7, 1-20, and approximately 300 nm, respectively). When phosphate was incubated with PT-A in human gastric and intestinal juices or in an aqueous solution containing BSA, the amounts of phosphate adsorbed by PT-A were not affected by the presence of proteins. The nitrogen adsorption/desorption isotherms and energy dispersive X-ray analyses demonstrated that phosphate could diffuse to the smaller tunnels freely even if the external surface of PT-A was covered with BSA. It was also demonstrated that the main site of adsorption for phosphate was in micropores of PT-A, whereas BSA was adsorbed only to the external surface and none entered inside smaller tunnels consisting of micro- and mesopores.

Adsorption↗

Sequence evolution of mitochondrial tRNA genes and deep-branch animal phylogenetics.

Mitochondrial DNA sequences are often used to construct molecular phylogenetic trees among closely related animals. In order to examine the usefulness of mtDNA sequences for deep-branch phylogenetics, genes in previously reported mtDNA sequences were analyzed among several animals that diverged 20-600 million years ago. Unambiguous alignment was achieved for stem-forming regions of mitochondrial tRNA genes by virtue of their conservative secondary structures. Sequences derived from stem parts of the mitochondrial tRNA genes appeared to accumulate much variation linearly for a long period of time: nearly 100 Myr for transition differences and more than 350 Myr for transversion differences. This characteristic could be attributed, in part, to the structural variability of mitochondrial tRNAs, which have fewer restrictions on their tertiary structure than do nonmitochondrial tRNAs. The tRNA sequence data served to reconstruct a well-established phylogeny of the animals with 100% bootstrap probabilities by both maximum parsimony and neighbor-joining methods. By contrast, mitochondrial protein genes coding for cytochrome b and cytochrome oxidase subunit I did not reconstruct the established phylogeny or did so only weakly, although a variety of fractions of the protein gene sequences were subjected to tree-building. This discouraging phylogenetic performance of mitochondrial protein genes, especially with respect to branches originating over 300 Myr ago, was not simply due to high randomness in the data. It may have been due to the relative susceptibility of the protein genes to natural selection as compared with the stem parts of mitochondrial tRNA genes. On the basis of these results, it is proposed that mitochondrial tRNA genes may be useful in resolving deep branches in animal phylogenies with divergences that occurred some hundreds of Myr ago. For this purpose, we designed a set of primers with which mtDNA fragments encompassing clustered tRNA genes were successfully amplified from various vertebrates by the polymerase chain reaction.

Animals↗

[In vivo effect of growth-inhibitor produced by Pseudomonas aeruginosa isolates and anti-pseudomonal drugs on model infection due to Pseudomonas aeruginosa].

Pseudomonas aeruginosa Nos. 1 and 5, each co-existing growth-inhibitor-producing and -nonproducing cells, were used in this study. An equal number of both cells (each 10(8) CFU/mouse) was challenged intraperitoneally to mice, and these cells in the heart blood and kidneys of mice were determined. Furthermore, the effect of piperacillin, ceftazidime and sisomicin on the cell distribution in mice was studied in the model infection due to P. aeruginosa Nos. 1 and 5. As a control experiment both cells of P. aeruginosa No. 1 were each challenged intraperitoneally at a dose of 10(8) CFU/mouse to mice of two groups, but there were no marked differences between the two types in cell counts of the heart blood or kidneys 9 hours after challenge. When a concomitant challenge of both cells (each 10(8) CFU/mouse) was performed in mice, the number of growth-inhibitor-producing cells of the heart blood and kidneys was about 100 times greater than that of the non-producing cells. These in vivo results were well comparable to the previous in vitro results and indicated that the inhibitor affected the invasion of the non-producing bacteria in the body in the model infection due to P. aeruginosa isolates consisting of the two types of cells. Similar results were obtained in mice with the model infection due to P. aeruginosa No. 5. Anti-pseudomonal drugs such as piperacillin (50 mg/mouse) and ceftazidime (50 mg/mouse) and sisomicin (1 mg/mouse) were given intramuscularly to mice infected concomitantly with both cells of P. aeruginosa No. 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Isolation and characterization of human and rat cardiac microvascular endothelial cells.

Although reciprocal intercellular signaling may occur between endocardial or microvascular endothelium and cardiac myocytes, suitable in vitro models have not been well characterized. In this report, we describe the isolation and primary culture of cardiac microvascular endothelial cells (CMEC) from both adult rat and human ventricular tissue. Differential uptake of fluorescently labeled acetylated low-density lipoprotein (Ac-LDL) indicated that primary isolates of rat CMEC were quite homogeneous, unlike primary isolates of human ventricular tissue, which required cell sorting based on Ac-LDL uptake to create endothelial cell-enriched primary cultures. The endothelial phenotype of both primary isolates and postsort subcultured CMEC and their microvascular origin were determined by characteristic histochemical staining for a number of endothelial cell-specific markers, by the absence of cells with fibroblast or pericyte-specific cell surface antigens, and by rapid tube formation on purified basement membrane preparations. Importantly, [3H]-thymidine uptake was increased 2.3-fold in subconfluent rat microvascular endothelial cells 3 days after coculture with adult rat ventricular myocytes because of release of an endothelial cell mitogen(s) into the extracellular matrix, resulting in a 68% increase in cell number compared with CMEC in monoculture. Thus biologically relevant cell-to-cell interactions can be modeled with this in vitro system.

Animals↗

Role of cation gradients in hypercontracture of myocytes during simulated ischemia and reperfusion.

We examined the relationship between transsarcolemmal cation gradients and hypercontracture of cardiac myocytes in ischemia and reperfusion using adult rat ventricular myocytes superfused with buffer mimicking normal or ischemic extracellular fluid. Contractile performance of electrically stimulated cells was recorded by an optical video system simultaneously with measurements of intracellular Ca2+ concentration ([Ca2+]i) using fura-2 or intracellular pH (pHi) using 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein. While cells were exposed to simulated ischemia buffer, the transsarcolemmal H+ gradient was abolished, [Ca2+]i transient stopped, and twitch contraction of myocytes ceased. Upon reperfusion with normal buffer, H+ gradient was quickly restored, Ca2+ transients restarted with transient increase in systolic Ca2+, and twitch contraction restarted with development of hypercontracture, which continued after [Ca2+]i returned to preischemic level even in the presence of near-normal concentrations of high-energy phosphates. When the transsarcolemmal proton, Na+, and Ca2+ gradients were altered so that Na+ entry via Na(+)-H+ exchange and Ca2+ entry via Ca(2+)-Na+ exchange were made less favorable, the transient systolic overshoot of Ca2+ at reperfusion and development of hypercontracture was largely avoided. These results suggest that Na+ and then Ca2+ entry via the Na(+)-H+ and Na(+)-Ca2+ exchangers, respectively, probably contribute to the increase in [Ca2+]i and hypercontracture of myocytes at time of reperfusion in this model.

Acidosis↗

Cell-cell signaling between adult rat ventricular myocytes and cardiac microvascular endothelial cells in heterotypic primary culture.

It is unclear whether signaling between endothelial cells and muscle cells within ventricular myocardium, known to be important during cardiac development, remains physiologically relevant in the adult heart. Also, the mechanisms regulating the synthesis and activation of locally acting autacoids such as endothelins, cytokines known to have potent effects on contractile function and gene expression in cardiac myocytes, are unknown, as their cells of origin within ventricular muscle. Microvascular endothelial cells isolated from ventricular tissue of adult rats do not express endothelins constitutively. However, the appearance of preproendothelin mRNA can be increased in cardiac microvascular endothelial cells by heterotypic primary culture with adult rat ventricular myocytes. Cell-cell contact, or at least close apposition, appears to be necessary to increase preproendothelin mRNA, as medium conditioned by ventricular myocytes alone was ineffective when applied to monocultures of microvascular endothelial cells. The level of TGF beta precursor mRNA is also markedly increased in microvascular endothelial cells in coculture and precedes the appearance of endothelin precursor transcripts. In coculture, TGF beta acts as an autocrine cytokine, increasing endothelin precursor mRNA and inhibiting the rate of microvascular endothelial cell proliferation. This regulation of endothelial cell phenotype in heterotypic primary cultures suggests that dynamic, reciprocal cell-cell signaling may also be occurring between microvascular endothelium and ventricular myocytes in vivo.

Amino Acid Sequence↗