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Biomedical subjects

T Yamaguchi

Publications and source records attributed to T Yamaguchi.

At least 217 records · Page 12Linked to original sources
PubMed2001

Effect of positively and negatively charged liposomes on skin permeation of drugs.

To clarify the effect of the surface charge of liposomes on percutaneous absorption, the permeation of liposomal drugs through rat skin was investigated in vitro and in vivo. Liposomes were prepared using egg yolk lecithin (EPC, phase transition temperature, -15 to -17 degrees C), cholesterol and dicetylphosphate (DP) or stearylamine (SA) (10:1:1, mol/mol). Also examined was the penetration behavior of positively and negatively charged liposomes, using a fluorescent probe (Nile Red). The in vitro penetration rate of melatonin (MT) entrapped in negatively charged liposomes was higher than that of positively charged ones (p<0.05). When the percutaneous absorption of ethosuximide (ES) encapsulated was estimated in vivo, the absorption of ES from negatively charged liposomes was slightly higher than that from positively charged liposomes. Additionally, the absorption of ES from both types of liposomes was superior to that from the lipid mixtures consisting of the same composition as the vesicles. The percutaneous absorption of betahistine (BH) from a gel formulation containing negatively charged liposomes of BH was much more than that from the formulation with positively charged ones, with 2-fold higher AUC (p<0.05). Histological studies revealed that the negatively charged liposomes diffused to the dermis and the lower portion of hair follicles through the stratum corneum and the follicles much faster than the positive vesicles at the initial time stage after application. Thus, the rapid penetration of negatively charged liposomes would contribute to the increased permeation of drugs through the skin.

Administration, Cutaneous↗
PubMed2001

[Development of new hydrophilic catheter kit for self-catheterization: study in pediatric cases].

PURPOSE: To increase the management of self-catheterization in children of school age, a catheter kit consisting of hydrophilic catheter and a packet containing sterilized water was developed. We evaluated the lubricating characteristic and clinical efficacy of this new catheter kit. MATERIALS AND METHODS: The catheter kit used in the study was a pocket-size plastic container in which a polyurethane catheter coated with hydrophilic polymer and a packet containing sterilized water were packed in combination. The lubricating characteristic of catheter was assessed by the measurement of friction value. For clinical assessment, male children aged over 6 years old who were doing self-catheterization at 17 medical institutions nationwide were selected as the subjects. The 32 children who had given informed consent (mean age: 11.6 years old) were asked to use the catheter kit continuously for 1 week. The results were investigated by a questionnaire survey in which the assessment before and after the use was expressed in scores. At the same time, urinalysis and urine culture were examined. RESULTS: The friction value of hydrophilic catheter was equivalent to or less than that observed by applying a lubricant to the conventional catheter. The comparison of conventional catheter with the kit indicated significantly higher scores (assessment in 5 grades expressed in scores) for the portability and operability of the kit. Though there was no significant difference in the ease of insertion between the two catheters, there were several comments that the kit got stuck in the urethra when it was withdrawn. The global assessment gave a significantly higher score to the kit and 30 (94%) of the 32 children wanted to use the kit continuously. No increase in hematuria which caused a clinical problem or no new apparent urinary tract infection occurred after the use of the kit. CONCLUSIONS: Compared with the conventional catheter, the hydrophilic catheter kit highly satisfied a large number of children at the time of self-catheterization. Depending on the condition of children, the kit is considered useful for continued self-catheterization for a long term.

Child↗
PubMed2001

Bisabosquals, novel squalene synthase inhibitors. I. Taxonomy, fermentation, isolation and biological activities.

In the course of screening for yeast squalene synthase inhibitors, bisabosqual A was isolated from the culture broth of Stachybotrys sp. RF-7260. The related compounds bisabosquals B, C and D were also isolated from Stachybotrys ruwenzoriensis RF-6853. Bisabosquals inhibited squalene synthases. IC50 values of bisabosqual A against the microsomal squalene synthases from Saccharomyces cerevisiae, Candida albicans, HepG2 cell and rat liver were 0.43, 0.25, 0.95 and 2.5 microg/ml, respectively. Bisabosqual C exhibited inhibitory activities similar to bisabosqual A. Bisabosqual A showed broad spectrum antifungal activity in vitro.

Animals↗
PubMed2001

Diffusion-weighted MR imaging in a case of mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes.

In a patient with mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS), both T2- and diffusion-weighted MR imaging revealed lesions as hyperintense areas in the occipital lobes early after strokelike episodes. In these lesions, no significant reduction in apparent diffusion coefficient was noted. Apparent diffusion coefficient mapping may help to differentiate strokelike episodes in MELAS from acute ischemic stroke. The strokelike episodes may be related to vasogenic edema and hyperperfusion, which were suggested by our single-photon emission CT and MR imaging studies.

Adult↗
PubMed2001

Diagnosis of internal carotid artery stenosis greater than 70% with power Doppler duplex sonography.

BACKGROUND AND PURPOSE: Duplex sonography is an effective tool for evaluating internal carotid artery (ICA) stenosis, and power Doppler imaging has improved its value in this regard. Our goal was to elucidate which parameters, such as linear stenosis, area stenosis, and peak systolic velocity (PSV), are the most reliable predictors of ICA stenosis greater than 70% using the method proposed by the North American Symptomatic Carotid Endarterectomy Trial (NASCET). METHODS: Duplex sonography with power Doppler imaging and cerebral angiography were performed prospectively in 75 patients (135 vessels). The grade of stenosis on angiograms was calculated by the NASCET method, and linear stenosis, area stenosis, and PSV were measured in the most stenotic part of the ICA. RESULTS: Angiography revealed 20 ICA vessels with stenosis greater than 70%. The correlation between angiographic stenosis and linear stenosis, area stenosis, and PSV was .82, .78, and .84, respectively. A sensitivity-specificity curve analysis determined optimal threshold values of linear stenosis, area stenosis, and PSV as predictors of ICA stenosis greater than 70% as 74.7%, 83.3%, and 200 cm/s, respectively. Calculations of positive and negative predictive values, and accuracy using the optimal threshold values were 90.5%, 99.1%, and 97.8% for linear stenosis; 76.0%, 99.1%, and 94.8% for area stenosis; and 100%, 100%, and 100% for PSV. CONCLUSION: All parameters corresponded relatively well with angiographic stenosis. In particular, PSV greater than 200 cm/s was the most reliable predictor of ICA stenosis greater than 70%. We believe that the combination of parameters plays a crucial role in the accurate assessment of ICA stenosis.

Adult↗
PubMed2001

[13C-urea breath test].

A 13C-urea breath test(13C-UBT) is known to be a good diagnostic method for detecting H. pylori infection since it is non-invasive, simple and accurate. Its diagnostic capability in determining H. pylori eradication has been studied using 153 patients (who underwent the H. pylori eradication therapy) as subjects at two times: 6-8 weeks after the end of administration (at the time of determination of eradication) and 6 months afterwards. When determination was made, the sensitivity and specificity of 13C-UBT compared to culture and histology were 100% and 95.1%, respectively. Seven inconsistent cases were positive according to 13C-UBT and negative according to two other methods. After 6 months, both sensitivity and specificity were 100% and 4 of the 7 inconsistent cases became positive according to all three methods. These results indicate that the 13C-UBT is superior in terms of sensitivity and specificity to culture and histology and recognize the failure eradication earlier than ether two methods. Re-examination of inconsistent cases should be performed after 6 months. After covered by insurance, the H. pylori eradication therapy will become a general form of treatment of peptic ulcers. 13C-UBT in particular has proven most useful for diagnosis of eradication.

Breath Tests↗
PubMed2001

[Induction chemotherapy (cisplatin + vinorelbine) is found to be markedly effective for squamous cell lung carcinoma with sarcoidosis--a case report].

A sixty-one-year-old man was admitted to our hospital because of a right lung tumor shadow. He had been diagnosed as having sarcoidosis at the age of fifty-seven. He was newly diagnosed as having squamous cell carcinoma by trans bronchial biopsy. He was treated with an induction chemotherapy (cisplatin 80 mg/m2 + vinorelbine 20 mg/m2) followed by right middle and lower lobectomy with a mediastinal nodal dissection, because the stage of his carcinoma was cT2N2M0. Resected lung tissue showed the disappearance of cancer cells. Dissected mediastinal and hilar lymph nodes showed many sarcoid granulomas. Cisplatin combined with vinorelbine might be an effective chemotherapy for non-small cell lung carcinoma.

Antineoplastic Agents↗
PubMed2001

Significance of integrin alpha2/beta1 in peritoneal dissemination of a human gastric cancer xenograft model.

In the present study, the role of integrin alpha2/beta1 in peritoneal dissemination of gastric cancer was investigated using an in vivo xenograft model for the highly metastatic MKN-45-P gastric cancer cells. Metastatic ability of MKN-45-P cells was significantly associated with the simultaneous expression of integrin alpha2 and alpha3 subunits. In an in vitro adhesion assay, neutralizing antibody for integrin alpha2 or beta1 subunit inhibited the adhesion of MKN-45-P cells to collagen type I and type IV. Moreover, the injection of anti-beta1 monoclonal antibody reduced the number of cancer cells on the peritoneum in nude mice that had been inoculated with MKN-45-P cells. These results suggest that integrin alpha2/beta1 represents a candidate target molecule available for the prevention of gastric cancer peritoneal dissemination.

Adenocarcinoma↗
PubMed2001

Neurometer measurement of current stimulus threshold in rats.

We examined the current stimulus threshold in rats with the Neurometer, a device used clinically for measuring perception and pain thresholds. Although many studies have indicated the usefulness of this device in the quantification of nerve dysfunction in patients, we have found no published reports on the use of the Neurometer in animals. Transcutaneous nerve stimuli of the three sine-wave pulses produced by the Neurometer (at 2000, 250, and 5 Hz) were applied to plantar surface of rats. The intensity of each stimulation at which rats vocalized or were hardly startled was defined as the current stimulus threshold. With repeated stimulation, the thresholds were almost constant. Repeated topical application to the area around the stimulating electrode of a high concentration of capsaicin, which acts on small-diameter fibers, increased the thresholds at 250 and 5 Hz, but did not affect the 2000-Hz threshold. Intravenous morphine (2-5 mg/kg) increased all three thresholds, whereas intrathecal morphine (20 or 80 microg) increased only the 5-Hz threshold. Intravenous injection of a minor tranquilizer, diazepam, at 1 mg/kg raised the thresholds at 2000 and 250 Hz, but did not affect the 5-Hz threshold. Higher dose of diazepam increased all three thresholds. These results suggest that the Neurometer makes possible selective examination of subsets of nerve fibers that differ in diameter not only in humans but also in animals. The present study in rats, in which we established a method of measurement, may provide helpful suggestions for the interpretation of data in humans.

Animals↗
PubMed2001

Coronary artery disease as a definitive risk factor of short-term outcome after starting hemodialysis in diabetic renal failure patients.

Cardiovascular disease is a major cause of morbidity and mortality in patients with diabetes who are receiving dialysis. It is known that cardiac mortality is high in the first year of hemodialysis (HD). The purpose of this study was to clarify the prevalence of coronary artery disease (CAD) in patients with diabetes at the initiation of HD, and to investigate the relationship between short-term outcomes after starting hemodialysis and CAD. We performed coronary angiography (CAG), whether or not patient had angina, within one month of initiation of maintenance HD in 17 of 34 consecutive unselected diabetic patients. We studied the two-year survival rate of those with CAD. Eleven patients (65%) were classified CAD-positive. Nine (82%) of these 11 had multivessel disease. Clinical and hematologic factors did not differ significantly between the groups with and without CAD. During the two-year follow-up period, 28 (82%) of 34 patients survived. In patients with CAD the two-year survival rate was 60%. None of the patients without CAD died within 2 years after starting HD. These results suggest that the presence of CAD at the initiation of HD may play a critical role in short-term outcomes after starting HD. We believe that an evaluation of CAD should be performed at the initiation of HD.

Chi-Square Distribution↗
PubMed2001

[Clinical characteristics of emerging multiple-drug-resistant gram-negative rods producing extended-spectrum beta-lactamases (ESBLs)].

The prevalence of organisms producing extended-spectrum beta-lactamases(ESBLs) has been increasing all over the world. ESBLs confer resistance to cefotaxime, ceftazidime, aztreonam, extended-spectrum penicillins, and structurally related beta-lactams in clinical isolates of K. pneumoniae and E. coli. Under the influence of antimicrobial agents, bacteria that primarily produce TEM-type or SHV-type beta-lactamases developed point mutations in structural genes which served to extend the substrate specificity of the enzymes. Infections caused by ESBLs producing isolates are difficult to detect with current susceptibility tests, and are difficult to treat. This article provides an historical overview of the emergence of ESBLs carrying gram-negative rods and consider how to treat their infections.

Drug Resistance, Multiple↗
PubMed2001

Effect of pneumoperitoneal pressure on tumor dissemination and tumor recurrence at port-site and midline incisions.

Over the past several years numerous cases of port site tumor recurrence after laparoscopic resection of a cancerous tissue have been reported. Possible mechanisms for tumor seeding include tumor removal, contaminated instruments, pneumoperitoneum, and aerosolization of tumor cells. This experiment examined the relationship among trocar contamination, aerosolization, and tumor recurrence with increasing pneumoperitoneal pressure using a hamster model. Increased pneumoperitoneal pressure significantly increased both instrument contamination and tumor recurrence at midline and port site incisions. Interestingly, increasing pneumoperitoneal pressure had no significant effect on the number of aerosolized tumor cells. The results reaffirm that the use of a reduced pneumoperitoneum or gasless laparoscopy may significantly lower port site tumor recurrence.

Animals↗
PubMed2001

[Results and limitations of arterial infusion therapy for liver metastases from colorectal cancer].

In our institution, patients with multiple unresectable liver metastases from colorectal cancer have received 24-h continuous arterial infusion therapy of 5-fluorouracil (5-FU) 250 mg/body/day every 2 weeks for the past 11 years. Although the 5-year survival rate of those who underwent surgical resection was 35%, that of unresectable patients who received 5-FU arterial infusion was 24% at 2 years, 9% at 3 years, and 50% survived a median of 391 days. Furthermore, we were able to perform surgical resection of metastatic residual lesions in patients who responded to 5-FU arterial infusion. This therapy has proven so effective that the 3-year survival rate of these patients is now 38%, and complete cures are being achieved.

Antimetabolites, Antineoplastic↗
PubMed2001

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (1999). I. Susceptibility distribution].

The bacterial strains isolated from patients diagnosed as having urinary tract infections (UTIs) in 9 institutions in Japan were supplied between the period of August 1999 to July 2000. Then, the susceptibilities of them to many kinds of antimicrobial agents were investigated. The number of them were 499 strains. The breakdown of these strains was Gram-positive bacteria as 31.3% and Gram-negative bacteria as 68.7%. Susceptibilities of these bacteria to antimicrobial agents were as follows; vancomycin (VCM), ampicillin (ABPC) and imipenem (IPM) showed strong activities against Enterococcus faecalis. The increase of low-susceptible strains which was noticed in the former year showed a slight recovery in this year. VCM showed a strong activity against MRSA preventing growth of all strains with 1 microgram/ml. In addition, the activity of arbekacin (ABK) was also strong with the MIC90 of 2 micrograms/ml against MRSA. However, MSSA and MRSA showing low susceptibilities were detected in one strain each (MIC: 16 micrograms/ml and 32 micrograms/ml, respectively). Carbapenems showed high activities against Citrobacter freundii and Escherichia coli. Meropenem (MEPM) prevented growth of all strains within 0.125 microgram/ml. Quinolone resistant E. coli decreased in this year compared with those in the last year, that percentage was less than 5%. Almost all drugs showed strong activities against Klebsiella pneumoniae and Proteus mirabilis. MEPM and carumonam (CRMN) prevented growth of all strains within 0.125 microgram/ml. On the other hand, one strain of K. pneumoniae showing resistance to cefaclor (CCL) and one strain of P. mirabilis showing low susceptibility to most of cephems were detected. Against Pseudomonas aeruginosa, almost drugs were not so active. The MIC90s of carbapenems were 8 micrograms/ml and those of all other drugs were more than 16 micrograms/ml.

Anti-Bacterial Agents↗
PubMed2001

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (1999). II. Background of patients].

Five-hundred forty four bacterial strains isolated from 412 patients diagnosed as having urinary tract infections (UTIs) in 9 institutions in Japan were supplied between the period of August 1999 to July 2000. Then, the clinical background of patients were investigated such as sex, age and type of infections, infections and kind of bacteria, frequency of isolation of bacteria by age and infections, bacteria and infections by timing of administration of antibiotics, and bacteria and infections by surgical procedures. About the relationship between age and sex of patients and type of infections, the number of male patients aged less than 50 years was few, and complicated UTIs without indwelling catheter was the most frequent. In females, the number of patients aged less than 20 years was few. Complicated UTIs without indwelling catheter was the most frequent among female patients aged between 40 to 59 years, in other age groups, uncomplicated UTIs was most frequent. As for type of infections and kind of bacteria, Escherichia coli decreased when the infections became complicated, and Pseudomonas aeruginosa and Enterococcus faecalis increased when the infection became complicated. Considering this result by age of patients, isolation frequency of E. coli was gradually decreased with aging in patients aged more than 20 years with uncomplicated UTIs or complicated UTIs without indwelling catheter. The isolation frequencies of E. faecalis and Staphylococcus aureus were gradually increased with aging in complicated UTIs without indwelling catheter. In patients with complicated UTIs with indwelling catheter, there was no difference between age group, and P. aeruginosa and E. faecalis were frequently isolated. As for type of causative organisms in UTIs before and after the administration of antibiotics, the isolation of bacteria was remarkably decreased after administration in patients with uncomplicated UTIs and complicated UTIs without indwelling catheter. E. coli decreased after administration of antibiotics, and P. aeruginosa and E. faecalis increased after administration in patients with all infections. As for type of causative organisms in UTIs and surgical procedures, E. coli were more frequently isolated in patients with uncomplicated UTIs when surgical procedures were experienced. Also, Klebsiella spp. and E. faecalis were more frequently isolated in patients with surgical procedures. However, in complicated UTIs, type of causative organisms had no relationship with surgical procedures.

Adolescent↗
PubMed2001

[Therapeutic efficacy of a topical tolnaftate preparation in guinea pig model of tinea pedis].

The therapeutic efficacy of a topical antifungal ointment containing 2% tolnaftate was studied in a guinea pig model of tinea pedis using the following four topical antifungal preparations commercially available as reference drugs: variotin (3,000 U/g ointment); phenyl-11-iodo-10-undecynoate (0.5% ointment); siccanin (1% ointment); and clotrimazole (1% cream). After the infection fully developed, the infected animals were treated twice daily with the testing drug or reference drug for consecutive four weeks. Therapeutic efficacy was mainly evaluated on the basis of the extent of the yield of fungal cultures from the infected skin tissues (infection intensity) at the end of the treatment period. In animal groups treated with tolnaftate as well as with three reference drugs, siccanin, phenyl-11-iodo-10-undecynoate and clotrimazole, the average infection intensity was significantly lower than that for untreated control group (P < 0.05-0.005) although no culture-negative animal was seen in any treated animal group. Comparing with all the reference drugs, tolnaftate was the most highly effective and there was significant difference in the average infection intensity between a tolnaftate treated and each reference drug-treated groups (P < 0.01-0.005). These results confirm the clinical usefulness of the current tolnaftate preparation in the treatment of patients with tinea pedis and probably other clinical forms of dermatophytoses.

Administration, Topical↗