Search PubMed⌕ Search

Biomedical subjects

R Kitamura

Publications and source records attributed to R Kitamura.

At least 19 recordsLinked to original sources
PubMed2001

Improvement in precision of the liquid chromatographic-electrospray ionization tandem mass spectrometric analysis of 3'-C-ethynylcytidine in rat plasma.

During the development of the liquid chromatography with electrospray ionization-tandem mass spectrometry for the quantitative determination of 3'-C-ethynylcytidine (I) in rat plasma, ion suppression caused by the matrix components was observed for I and its structural analogue, 3'-C-ethylcytidine (II) as the internal standard. In the method initially designed, I/II peak area ratios varied according to the degree of matrix effect, which led to the poor precision of the assay. From the examination of the ion suppression behavior for I and II, it was assumed that this phenomenon is attributed to the difference in the retention time between I and II. Based on this assumption, therefore, the methanol content in the mobile phase was changed from 5 to 25% so as to make I and II the same retention time. As a result of this modification of the initial method, the precision expressed as relative standard deviation was improved from 5.2-16.2 to 2.7-4.2% in intra-assay and from 6.8-14.9 to 3.5-7.2% in inter-assay validations.

Animals↗
PubMed2001

[Pulmonary embolism during laparoscopic cholecystectomy detected by sudden decrease in end-tidal carbon dioxide pressure].

We report a case of intraoperative pulmonary embolism, detected by a sudden decrease in end-tidal carbon dioxide pressure (PETCO2). The patient was a 56-year-old female without any history of pulmonary disease. The patient was intubated and ventilated manually during the operation under anesthesia with sevoflurane, nitrous oxide, and vecuronium. The percutaneous oxygen saturation (SpO2) and PETCO2 were monitored continuously. Twenty minutes after starting the laparoscopic procedure, PETCO2 decreased suddenly from values between 34 and 38 mmHg to 24 mmHg, and SpO2 decreased from 99% to 95%. Nitrous oxide was discontinued. Removal of the drape revealed profound subcutaneous emphysema. Postoperative pulmonary scanning revealed areas with reduced pulmonary perfusion (Fig. 2). An intravenous bolus of heparin (3000 IU) was given immediately, followed by 10,000 IU heparin over the next 24 hours. The patient was discharged on the fifteenth postoperative day without any sequelae. Although monitoring pulmonary arterial pressure is generally considered a more reliable method for the early detection of pulmonary embolism, an invasive monitoring procedure, such as the insertion of a Swan-Ganz catheter, is usually not indicated in laparoscopic surgery. For the early detection of pulmonary embolism, we therefore recommend the continuous monitoring of PETCO2 during laparoscopic surgery.

Anesthesia, General↗
PubMed2001

[Multi-institutional cooperative study on combination chemotherapy with THP, CDDP and 5-FU for squamous cell carcinoma of the head and neck].

Combination chemotherapy with THP, CDDP and 5-FU for squamous cell carcinoma of the head and neck was conducted in 13 institutions in Hyogo Prefecture as a multi-institutional cooperative study. In the initial study (Nov. 1990-Nov. 1993), THP was administered intravenously at 20 mg/m2 on day 1, CDDP at 80 mg/m2 on day 2, and 5-FU at 1,000 mg/body/day in a continuous drip infusion for 120 hours from day 2 to day 6. In the second study (May, 1996-Mar. 1998), THP was administered at 20 mg/m2 on day 1, 5-FU at 10 mg/kg/day from day 1 to day 5, and CDDP at 70 mg/m2 on day 6 in the same way as the initial study. Forty-nine patients (Stage I in 3, Stage II in 12 including 2 recurrent cases, Stage III in 6, Stage IV in 28 including 3 recurrent cases; 1 course chemotherapy in 13 and 2 or more courses in 36) were subjected as complete cases in the initial study, and 36 patients (Stage I in 5 including one recurrent case, Stage II in 11 including 1 recurrent case, Stage III in 9 including 2 recurrent cases, Stage IV in 11 including one recurrent case; 1 course in 18 and 2 or more courses in 18) in the second. The overall response rate was 65.3% (CR in 3 cases) in the initial study and 63.9% (CR in 5 cases) in the second. Primary cases showed a response rate of 65.9% (29/44) in the initial study and 71.0% (22/31) in the second, whereas recurrent cases showed a 60.0% (3/5) response rate in the initial study and a 20.0% (1/5) rate in the second. Treatment-naive patients showed a response rate of 72.7% (24/33) in the initial study and 71.0% (22/31) in the second, whereas previously treated patients showed a 50.0% (8/16) response rate in the initial study and a 20.0% (1/5) rate in the second. Adverse reactions of more than Grade 3 in the initial study were leukopenia in 18.4%, thrombocytopenia in 8.2%, decrease of hemoglobin in 6.1%, loss of hair in 6.1%, anorexia in 36.7%, nausea and vomiting in 26.5%, and diarrhea in 4.1%, whereas those of Grade 3 in the second study were decrease of hemoglobin in 2.8%, anorexia in 22.2% and nausea and vomiting in 8.3%. From these results, it is suggested that the regimen in the second study was more useful than that in the initial study.

Adult↗
PubMed2000

Progress reports on immune gene therapy for stage IV renal cell cancer using lethally irradiated granulocyte-macrophage colony-stimulating factor-transduced autologous renal cancer cells.

There is no effective treatment for patients with stage IV renal cell cancer (RCC), although the introduction of new therapy is imminent. Cancer gene therapy is currently considered to be one of the most promising therapeutic modalities in the field of cancer treatment. Based on the results of animal studies, vaccination using autologous granulocyte-macrophage colony-stimulating factor-transduced renal cancer cells appears promising. Before initiating a clinical study using an ex vivo gene-transduced autologous cell vaccine-based immunogene therapy for RCC in Japan, in 1992 we initially planned a Japanese version of a clinical protocol in collaboration with a US group. In 1993, the original protocol was refined. We performed five preclinical qualification studies using RCC nephrectomy specimens from patients in 1997, and the results showed that preparation of RCC cells for autologous vaccines at the Clinical Cell Technology Facility, Research Hospital of the Institute of Medical Science, University of Tokyo, was feasible. Subsequently in August 1998, the Ministry of Health and Welfare and the Ministry of Education, Science, Culture, and Sport approved our clinical protocol. We have recruited two patients with stage IV RCC to our study so far. Here we report the background to the initiation of cancer gene therapy in Japan.

Adult↗
PubMed2000

gp100 mRNA is more sensitive than tyrosinase mRNA for RT-PCR amplification to detect circulating melanoma cells in peripheral blood of melanoma patients.

Two different melanocyte-specific mRNAs are studied as markers for circulating melanoma cells in vitro using the human melanoma cell line G361 and in vivo using blood samples from Japanese melanoma patients at different clinical stages. These mRNAs encode tyrosinase, the most essential enzyme for melanin synthesis, and gp100, a melanosomal matrix glycoprotein recognized by monoclonal antibody HMB-45. We used reverse-transcription polymerase chain reaction (RT-PCR) to detect tyrosinase mRNA and gp100 mRNA in peripheral blood. Since melanocytes would not normally be present in peripheral blood, the detection of those transcripts should indicate the presence of circulating melanoma cells. RT-PCR detection of these two mRNAs was highly sensitive and specific. Our in vitro study showed that as few as 10 melanoma cells in 0.125 ml normal blood could be detected. In in vivo study, 130 blood samples from 55 melanoma patients gave positive and variably sensitive results, whereas no samples from healthy controls or patients with other cancers gave positive results. Tyrosinase mRNA was not detected in any of the melanoma patients. gp100 mRNA was detected in 12 of 55 melanoma patients, in none of five stage I patients (0%), in four of 26 stage II patients (15.4%), in one of six stage III patients (16. 7%) and in seven of 18 stage IV patients (38.9%). Thus gp100 mRNA is a more sensitive marker for detecting circulating melanoma cells compared with tyrosinase mRNA.

Antibodies, Monoclonal↗
PubMed2000

Detection of circulating melanoma cells by RT-PCR amplification of three different melanocyte-specific mRNAs in a mouse model.

Three different melanocyte-specific mRNAs are studied as potential markers for circulating melanoma cells in the serum of mice inoculated subcutaneously with B16F10 melanoma cells. These three mRNAs encode tyrosinase, tyrosinase related protein-2 (TRP-2) and Pmel17, proteins that are essential for the synthesis of melanin and are expressed specifically in melanocytes. We used reverse-transcription polymerase chain reaction (RT-PCR) to detect these three different melanocyte-specific mRNAs in the sera of B16F10 bearing mice. Since melanocytes would not normally be present in the blood, the detection of those transcripts should indicate the presence of circulating melanoma cells. RT-PCR detection of all three mRNAs was highly sensitive and specific. Our in vitro studies show that as few as 10 melanoma cells can be detected in 125 microl blood and that in vivo, melanoma cells can be detected in blood samples from B16F10 melanoma bearing mice. Of these three mRNAs, Pmel17 mRNA is the most sensitive marker for detecting circulating melanoma cells compared with tyrosinase mRNA and TRP-2 mRNA. Moreover, this mouse model might be useful for basic research of malignant melanoma patients with haematogenous metastasis.

Animals↗
PubMed2000

[Perioperative management of a patient with a history of over-the-counter analgesic abuse for 20 years].

A 67-year-old man, complicated with liver cirrhosis, diabetes mellitus, and ischemic heart disease, was scheduled for gastrectomy. He had been taking an over-the-counter (OTC) analgesic containing acetaminophen, ethenzamid and caffeine for 20 years, and refused to stop taking it preoperatively. He received general anesthesia with isoflurane, supplemented with fentanyl and midazolam. Muscle relaxation was obtained with vecuronium. Isosorbide was infused continuously to prevent myocardial ischemia. The anesthetic course was uneventful. Postoperatively, the patient experienced no difficulty in abstaining from taking the OTC analgesic. The patient's perioperative course indicates that he was not dependent on this OTC drug, but he needed this medication only to ameliorate his preoperative anxiety or depressive mood.

Acetaminophen↗
PubMed1999

Small cell undifferentiated carcinoma of the submandibular gland: immunohistochemical evidence of myoepithelial, basal and luminal cell features.

A primary small cell undifferentiated carcinoma of the submandibular gland is reported. Histological studies revealed that the major part of this tumor was composed of cells slightly larger (10-14 microm) than lymphocytes. These tumor cells showed myoepithelial-cell differentiation, which was confirmed by the immunohistochemical and ultrastructural findings. Furthermore, some of them showed luminal-cell and basal-cell differentiation immunohistochemically. However, there was no evidence of neuroendocrine differentiation. These findings demonstrated that the tumor had the features of all the salivary ductal components (myoepithelial, basal, and luminal cells) and supported that the tumor might arise from the salivary duct. Furthermore, it supports the hypothesis of multipotential stem cells as the origin for small cell undifferentiated carcinomas in salivary glands.

Actins↗
PubMed1998

Disturbed CD4+ T cell homeostasis and in vitro HIV-1 susceptibility in transgenic mice expressing T cell line-tropic HIV-1 receptors.

T cell line-tropic (T-tropic) HIV type 1 strains enter cells by interacting with the cell-surface molecules CD4 and CXCR4. We have generated transgenic mice predominantly expressing human CD4 and CXCR4 on their CD4-positive T lymphocytes (CD4+ T cells). Their primary thymocytes are susceptible to T-tropic but not to macrophage-tropic HIV-1 infection in vitro, albeit with a viral antigen production less efficient than human peripheral blood mononuclear cells. Interestingly, even without HIV infection, transgenic mice display a CD4+ T cell depletion profile of peripheral blood reminiscent of that seen in AIDS patients. We demonstrate that CD4+ T cell trafficking in transgenic mice is biased toward bone marrow essentially due to CXCR4 overexpression, resulting in the severe loss of CD4+ T cells from circulating blood. Our data suggest that CXCR4 plays an important role in lymphocyte trafficking through tissues, especially between peripheral blood and bone marrow, participating in the regulation of lymphocyte homeostasis in these compartments. Based on these findings, we propose a hypothetical model in which the dual function of CXCR4 in HIV-1 infection and in lymphocyte trafficking may cooperatively induce progressive HIV-1 infection and CD4+ T cell decline in patients.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Effects of isoflurane on receptor-operated Ca2+ channels in rat aortic smooth muscle.

We have investigated the effects of isoflurane on receptor-operated Ca2+ channels (ROC) in vascular smooth muscle. In isolated rat thoracic aortic rings denuded of endothelium, the effects of isoflurane on phenylephrine-induced contraction and Ca2+ influx were evaluated in the presence of supramaximal doses of nifedipine or verapamil. Under isometric tension recording, the aortic rings were precontracted by phenylephrine 300 nmol litre-1 and exposed to 1.2%, 2.3% or 3.5% isoflurane. Phenylephrine-induced precontraction was enhanced with 2.3% isoflurane by mean 8.1 (SD 9.3)% (P < 0.05 vs 0% isoflurane). The constrictor effect of 2.3% isoflurane was not inhibited by depletion of intracellular Ca2+ stores with ryanodine 20 mumol litre-1, but was abolished in a Ca(2+)-free solution or by SK&F 96,365 30 mumol litre-1, an ROC blocker. Isoflurane-induced contraction was accompanied by increased intracellular free Ca2+ concentration, monitored using fura PE3. Unidirectional 45Ca2+ influx measurement in phenylephrine-stimulated aortic strips revealed that the mean amount of Ca2+ influx was significantly (P < 0.05) enhanced by 1.2% and 2.3% isoflurane, which were 117.1% and 119.7% of control values, respectively. Our results strongly suggest that isoflurane enhanced Ca2+ influx through ROC that had been submaximally activated by phenylephrine.

Anesthetics, Inhalation↗
PubMed1997

Determination of S-1 (combined drug of tegafur, 5-chloro-2,4-dihydroxypyridine and potassium oxonate) and 5-fluorouracil in human plasma and urine using high-performance liquid chromatography and gas chromatography-negative ion chemical ionization mass spectrometry.

A high-performance liquid chromatography (HPLC) and gas chromatography-negative ion chemical ionization mass spectrometry (GC-NICI-MS) method was developed for the analysis of the combined antitumor drug S-1 (tegafur, 5-chloro-2,4-dihydroxypyridine and potassium oxonate) and active metabolite 5-fluorouracil in human plasma and urine. Tegafur was fractionated from biological fluids by extraction with dichloromethane and analyzed by HPLC. 5-Fluorouracil and 5-chloro-2,4-dihydroxypyridine were extracted with ethyl acetate from the residual layer after extraction of tegafur, and converted to pentafluorobenzyl (PFB) derivatives. Potassium oxonate was cleaned up with an anion-exchange column (Bond Elut NH2). The extracted potassium oxonate was degraded to 5-azauracil and converted to PFB derivatives. The PFB derivatives were analyzed by GC-NICI-MS. A stable isotope was employed as the internal standard in the GC-NICI-MS analysis. The limits of quantitation of tegafur, 5-fluorouracil, 5-chloro-2,4-dihydroxypyridine and potassium oxonate in plasma were 10, 1, 2 and 1 ng/ml, respectively. The reproducibility of the analytical method according to the statistical coefficients is approximately 10%. The accuracy of the method is good; that is, the relative error is < 10%. The methods were applied to pharmacokinetic studies of S-1 in patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1997

Determination of a new podophyllotoxin derivative, TOP-53, and its metabolite in rat plasma and urine by high-performance liquid chromatography with electrochemical detection.

A high-performance liquid chromatographic method was developed for the determination of a new podophyllotoxin derivative, TOP-53 (I), and TOP-53 glucuronide (II) as its major metabolite in rat plasma and urine. For the analysis of I, the sample was chromatographed on a reversed-phase C18 column with electrochemical detection after consecutive two-step liquid-liquid extractions. Compound II was determined as I after enzymatic hydrolysis of II. This method was validated sufficiently with respect to specificity, accuracy, and precision. The limits of quantitation for both I and II were 2 ng/ml in plasma and 10 ng/ml in urine. The method is thus useful for the pharmacokinetic study of I.

Animals↗
PubMed1997

Suppression of cyclic guanosine monophosphate formation in rat cerebellar slices by propofol, ketamine and midazolam.

PURPOSE: The nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) system is involved in glutamatergic neurotransmission. The current study determined the effects of propofol, ketamine and midazolam on rat cerebellar cGMP formation, attempting to clarify whether the effect was due to suppression of NO-cGMP system or to direct interaction with glutamatergic receptors. METHODS: Cerebellar slices, obtained from six- to eight-day-old Wistar rats, were pretreated with propofol (10 microM-1 mM), ketamine (10-100 microM) or midazolam (1-100 microM) for 30 min. and then stimulated with L-glutamate (3 mM), N-methyl-D-aspartate (NMDA, 0.1 mM), kainate (0.1 mM) or sodium nitroprusside (SNP, 0.3 mM) (n = 5-11 for each group). The levels of cGMP were determined by radioimmunoassay. RESULTS: None of the anaesthetics studied altered cGMP levels when no stimulant was given. Propofol (10 microM-1 mM) suppressed L-glutamate-, NMDA-, kainate- and SNP stimulated cGMP formation in a concentration-dependent manner, the sensitivity to propofol was in the order of NMDA > kainate > L-glutamate. SNP. Ketamine (10-100 microM) suppressed L-glutamate- and NMDA-stimulated cGMP formation, but did not suppress kainate- or SNP-stimulated cGMP formation. Midazolam (10-100 microM) did not affect NMDA-, L-glutamate- or SNP-stimulated cGMP formation, but suppressed kainate-induced formation. CONCLUSION: The inhibitory effects of propofol, ketamine and midazolam on cGMP formation in rat cerebellar slices are due mainly to interaction with receptors for excitatory amines, and not due to the suppression of nitric oxide synthase or guanylate cyclase activities.

Anesthetics, Intravenous↗
PubMed1997

Suppression of acetylcholine-induced relaxation by local anesthetics and vascular NO-cyclic GMP system.

BACKGROUND: Local anesthetics have been demonstrated to attenuate acetylcholine-induced relaxation of vascular smooth muscle, but the mechanism responsible has not been elucidated. The present study was undertaken to ascertain whether this effect of local anesthetics is due to suppression of the vascular nitric oxide (NO)-cyclic GMP (cGMP) system. METHODS: Isolated rat aortae were cut into helical strips and mounted in bathing solution to measure isometric tension changes. They were precontracted with phenylephrine (0.3 microM) then exposed to cumulative concentrations of relaxants including acetylcholine, sodium nitroprusside (SNP) and papaverine, in the absence or presence of local anesthetics. Aortae for cGMP measurements were cut longitudinally into pairs of strips and bathed in the solution without tension. In the absence or presence of anesthetics, they were stimulated with acetylcholine or SNP, and the cGMP content of each strip was radioimmunoassayed. RESULTS: Acetylcholine-induced, endothelium-dependent relaxation of phenylephrine-precontracted aortae was attenuated by lidocaine (30-300 microM), tetracaine (10-30 microM), bupivacaine (10-100 microM) and ropivacaine (30-100 microM). SNP-induced relaxation was attenuated by lidocaine (300 microM), tetracaine (30 microM), bupivacaine (10-100 microM) and ropivacaine (30-100 microM). Papaverine-induced relaxation was attenuated by lidocaine (300 microM), bupivacaine (30-100 microM) and ropivacaine (30-100 microM), and augmented by tetracaine (30 microM). Cyclic GMP levels in acetylcholine-stimulated aortae were reduced significantly by lidocaine (300 microM), tetracaine (100 microM) and bupivacaine (300 microM) treatment, but not by ropivacaine (300 microM). SNP-stimulated cGMP levels were reduced by tetracaine (100 microM) but not by any other anesthetics at the concentrations tested. CONCLUSION: We conclude that lidocaine, tetracaine and bupivacaine suppress acetylcholine-stimulated formation of cGMP. However, the attenuation of acetylcholine-induced relaxation by local anesthetics is not totally ascribable to reduced cGMP levels.

Acetylcholine↗
PubMed1997

Effect of cisternal papaverine on cerebral blood flow in patients with subarachnoid hemorrhage--three case reports.

Three patients presenting with subarachnoid hemorrhage due to aneurysmal rupture underwent cerebral blood flow (CBF) measurements before and after cisternal injection of papaverine hydrochloride. One patient showed prominent increases in CBF in the frontal lobe and basal ganglia after injection of papaverine, but paradoxical decreases in the parietal lobe and corona radiata. The other two patients had poor CBF response. Dense clotting in the basal cisterns may have prevented diffusion of the agent so that only the proximal trunks of the internal carotid, anterior cerebral, and middle cerebral arteries were dilated in the former case. The dilation of proximal trunks of cerebral arteries might steal blood flow from the parietal lobe and corona radiata, where the intraparenchymal arteries were maximally dilated and cerebrovascular reserve capacity was poor.

Adult↗
PubMed1997

Changes in DNA copy number in primary gastric carcinomas by comparative genomic hybridization.

We examined 33 primary gastric carcinomas using comparative genomic hybridization to detect changes in the DNA copy number and the chromosomal location of these changes. Ninety-four percent (31 of 33) showed 1 or more DNA copy number changes, such as increases at 2p23-p25 (observed in 21% of the total cases), 3q26.3-q27 (24%), 7p15 (24%), 9p22-pter (18%), and 13q22-q34 (21%) and decreases at 1p34.2-p36.2 (18%) and Y (52%). Histological examination indicated that increases at 3q26.1-q26.3 and 7p15 and decreases at 1p36.1-p36. 2 and Y were commonly observed in both differentiated and undifferentiated types. Increases at 3q27, 6q23-q25, and 7cen-p14 and decreases at 1p34.2-p35 and 17p12 were predominantly observed in the differentiated type, and increases at 2p23-pter, 9p22-pter, and 13q31-qter and a decrease at 6p21.3 were predominantly observed in the undifferentiated type. In addition, clinical staging of tumors showed that increases at 2p23-p25, 7p14-p21, 7q31-q32, and 9p22-pter and a decrease at Y were observed in early-stage tumors, whereas increases at 9q32-q33 and 15q26 were observed only in late-stage tumors. Many of the abnormalities detected in this study were not previously reported in gastric carcinomas. Our comparative genomic hybridization results indicate the presence of genetic alterations that may play some important role in the development and progression of gastric carcinomas.

Adult↗
PubMed1996

Establishment of transgenic mice carrying human fetus-specific CYP3A7.

CYP3A7 is a cytochrome P450 isozyme expressed prenatally in humans. Six lines of mice transgenic for human CYP3A7 were established by microinjecting a CYP3A7 cDNA downstream of a mouse metallothionein-1 promoter gene into the male pronucleus of fertilized mouse oocytes. The inserted CYP3A7 transgene was expressed at a mRNA level in a variety of tissues including the liver, kidney, lung, spleen, testis, small intestine, thymus, brain, skin, and heart of adult mice. The protein expression of the transgene was also detected in the liver and testis of line M10 mice. A significantly higher level of total testosterone in the serum was found in line M10 male mice. In addition, this transgenic line exhibited weight increases in the liver, kidney, and uterus but a decrease in the testis (P < 0.01). The transcript of the integrated CYP3A7 gene possessed the ability to activate aflatoxin B1 in Ames test in which the his+ revertants of Salmonella typhimurium TA100 per plate were significantly higher (P < 0.01) when liver microsomes of line M10 transgenic mice were used. This result demonstrates that the CYP3A7 gene has been integrated into the mouse genome and translated into a catalytically active enzyme. These transgenic mice are expected to give useful information for studies on fetal toxicities in humans.

Aflatoxin B1↗