CYP isoforms involved in the metabolism of clarithromycin in vitro: comparison between the identification from disappearance rate and that from formation rate of metabolites

To clarify whether CYP2C19 is involved in the overall metabolism of clarithromycin (CAM) or not, in vitro studies using human liver microsomes and recombinant CYPs were performed by an approach based on the disappearance rate of parent compound from the incubation mixture. In addition, the results of disappearance rate were compared with those obtained from the formation rates of the major metabolites of CAM, 14-(R)-hydroxy-CAM and N-demethyl-CAM.The intrinsic clearance (CL(int)) values determined from the disappearance of CAM in nine different human liver microsomes were highly correlated with the testosterone 6beta-hydroxylation activity (r=0.957, p<0.001). The CL(int) of CAM was markedly reduced by selective inhibitors of CYP3A4 (ketoconazole and troleandomycin) and by polyclonal antibodies raised against CYP3A4/5 in human liver microsomes. Among the 11 isoforms of recombinant human CYP, only CYP3A4 revealed the metabolic activity for the disappearance of CAM. These results were fairly consistent with those obtained from the conventional approach based on the formation of major metabolites of CAM. Comparison of the kinetic parameters estimated from the disappearance rate of CAM and the formation rates of 14-(R)-hydroxy-CAM and N-demethyl-CAM indicates that N-demethylation and 14-(R)-hydroxylation account for 65% of CL(int) derived from the disappearance of CAM in human liver microsomes.The findings suggest that CYP3A4 plays a predominant role in the overall metabolic clearance of CAM as well as in the formation of 14-(R)-hydroxy-CAM and N-demethyl-CAM. CYP2C19 does not appear to be involved in the overall metabolism of CAM at least in human liver microsomes. A combination of the disappearance rate of a parent compound and the formation rate of metabolites appears to be a useful approach for estimating the percentage contribution of the formation of metabolites to the overall metabolic clearance of a parent compound in vitro.     

Caffeine diminishes cytotoxic effects of paclitaxel on a human lung adenocarcinoma cell line

This study was performed to investigate how caffeine modifies the cytotoxic effects of paclitaxel on a human lung carcinoma cell line. Caffeine doses up to 5mM had less effect on clonogenic survival. The cell killing effect, due to paclitaxel, increased in a dose-dependent manner up to 50 nM. For combined treatment with caffeine and paclitaxel, added caffeine reduced the cytotoxic effect of paclitaxel not only in dose-response but also in time-response curves. Caffeine combined with paclitaxel clearly suppressed cell proliferation in a dose-dependent manner. In the cell cycle analysis, caffeine alone caused early G1 accumulation, whereas paclitaxel alone caused an early increase in G2-M and a decrease in G1. As for the effect of caffeine on paclitaxel, caffeine suppressed the effect of paclitaxel on cell cycle distribution, where a dose-dependent early increase in G2-M and a decrease in G1 were not clear. We suggest that cell cycle modifying agents, such as caffeine, potentially diminish the cytotoxic activity of paclitaxel, and one should be careful when combining such agents.     

Structures of five new carotenoids from the oyster Crassostrea gigas

Five new minor carotenoids, 1-5, were isolated from the oyster Crassostrea gigas. The structure of 1 was determined to be (3S,5R,6R,6'S)-3,5,6'-trihydroxy-3'-oxo-6,7-didehydro-5,6-dihydro-10,11,20-trinor-beta,epsilon-caroten-19',11'-olide 3-acetate by detailed analyses of NMR and CD data. The structures of the other carotenoids, 2-5, were also determined in a similar manner. In the FAB-MS/MS of 2-4, having the 5-hydroxy-3,6-epoxy-5,6-dihydro-beta-carotene moiety, the characteristic product ions resulting from the sequential cleavage of C-C bonds in the polyene chain were observed.     

Fourth ventricular meningioma in an adult--case report

A 72-year-old female presented with an intra-fourth ventricular meningioma manifesting as truncal ataxia. Computed tomography (CT) showed a slightly high-density, well-demarcated, and homogeneously enhanced mass located in the fourth ventricle and extending to the right lateral recess. T2-weighted magnetic resonance (MR) imaging revealed a peritumoral high-intensity band without dural tail sign. Bilateral vertebral angiography revealed faint tumor staining supplied from the choroidal branches of the posterior inferior cerebellar arteries. The mass was totally resected via a suboccipital approach. CT, T2-weighted MR imaging, and vertebral angiography are informative for the preoperative diagnosis of fourth ventricular meningioma.     

Determination of serum prostate-specific antigen-alpha1-antichymotrypsin complex for diagnosis of prostate cancer in Japanese cases

OBJECTIVE: The clinical utility of the determination of serum prostate-specific antigen-alpha1-antichymotrypsin complex (PSA-ACT) for the diagnosis of prostate cancer, especially in cases in the diagnostic gray zone, is still unclear. MATERIAL AND METHODS: With the use of a newly approved enzyme immunoassay for the detection of PSA-ACT, 907 sera, including those from non-urological benign and malignant diseases, were analysed. RESULTS: Serum values of PSA-ACT in non-prostate cancer males increased according to age from the 40s to 70s. The serum values were high only in the patients with prostatic diseases and, in prostate cancer patients, the values became high as the clinical stage progressed. By receiver-operating characteristic analysis significantly better results in PSA-ACT than total PSA were observed. In the group with a total PSA of 2-20 ng/ml, the detection of PSA-ACT showed better results, although not significantly so, than the free-to-total PSA ratio. CONCLUSIONS: The detection of PSA-ACT showed a high clinical utility in the diagnosis of prostate cancer. Therefore, it may replace total PSA determination.     

Radiation therapy for elderly patient with squamous cell carcinoma of the uterine cervix

OBJECTIVE: The purpose of this study was to profile cervical squamous cell carcinoma in elderly patients undergoing radiation therapy and to study the treatment outcome and side effects of therapy. MATERIALS AND METHODS: A retrospective analysis was carried out from the records of 380 patients with squamous cell carcinoma of the uterine cervix who had been given radiation therapy between 1970 and 1994. The patients were divided into three age groups: under 70 years (youngest group; n = 215), 70 to 79 years (intermediate group; n = 124), and 80 years or older (oldest group; n = 41). Radiation therapy was performed by a combination of external beam therapy and three brachytherapy fractions using low-dose-rate sources. RESULTS: The 5-year overall survival rates in the youngest, intermediate, and oldest groups were 58, 50, and 33%, respectively, while cause-specific survival rates were 68, 70, and 65%, respectively. For the patients with stage III, the 5-year overall survival rates in the youngest, intermediate, and oldest groups were 59, 48, and 36%, respectively, while cause-specific survival rates were 72, 70, and 70%, respectively. There was no statistical significance in the 5-year intrapelvic recurrence rates among the three groups. Grade 3 or 4 complications occurred in 6.5% of the youngest, 11.3% of the intermediate, and 7.3% of the oldest groups. CONCLUSION: Radiation therapy with external beam combined with three fractions of low-dose-rate brachytherapy proved both highly effective and safe for senior patients with cervical squamous cell carcinoma.     

Influences of percutaneous nephrolithotomy on renal function, an observation using the NAG-index and beta 2-microglobulin as indices

To examine the influence of percutaneous nephrolithotomy (PNL) on renal function, we measured the activity of urinary N-acetyl-beta-D-glucosaminidase (NAG) and beta 2-microglobulin (beta 2MG) in patients with nephrolithiasis, before and 3, 5, 7, 14 days and 1 month after PNL. With PNL, renal function was recovered within one month, and PNL was thought to be a more protective method than pyelolithotomy. Recovery of renal function was delayed in the cases in which PNL had been attempted over three times. In the patients with preoperative high-grade hydronephrosis, the excretion of NAG and beta 2MG in the urine was delayed. NAG-index was considered to be a more sensitive parameter than beta 2MG to evaluate renal function. The NAG-index and beta 2MG values of bladder urine were in good correlation with those of nephrostomy urine 5 days or more postoperatively. Measurement of the urinary NAG-index 3, 7, 14, 30 days after PNL operation was considered valuable for determining changes in renal function.     

Idiopathic Hypoglossal Nerve Laceration Detected by High‐Resolution Three‐Dimensional Constructive Interference in Steady State Magnetic Resonance Imaging

A 55‐year‐old man presented with acute onset dysarthria caused by left hypoglossal palsy. He had neither surgery nor injury prior to the onset of his symptoms. We detected no abnormalities with conventional magnetic resonance imaging (MRI) except for a slight gadolinium enhancement of the left hypoglossal nerve. Three‐dimensional constructive interference in steady state MRI (CISS MRI) showed curling and thickening of the left hypoglossal nerve and fluid accumulation in the hypoglossal nerve canal. A systemic survey found no malignancies. After 8 months, sustained left hypoglossal palsy and no change in the MRI led to the diagnosis of idiopathic hypoglossal nerve laceration with evulsion. In such patients, the cause of the defect is not always apparent and 3‐dimensional CISS MRI may resolve this issue.