Effect of latamoxef on platelet function and prothrombin time in partially nephrectomized rats

Latamoxef (daily 100 and 300 mg/kg, i.v.) was injected once a day for 8 days to 75% and 90% nephrectomized rats kept on a vitamin K-sufficient diet (500-600 ng/g) or a vitamin K-deficient diet (30-50 ng/g), and changes in ADP-induced platelet aggregation and prothrombin time were examined. The half-life of latamoxef was markedly prolonged and plasma latamoxef and N-methyltetrazolethiol (NMTT) concentrations increased, resulting in a delay of the total body clearance of the compounds. The ADP-induced platelet aggregation increased after nephrectomy, and latamoxef slightly but inconsistently decreased the aggregation. Prothrombin time did not change even in the 90% nephrectomized rats kept on an ordinary diet, but increased dose-dependently in the vitamin K-deficient nephrectomized rats, with the 90% nephrectomized animals showing larger increases of prothrombin time. These data suggest that NMTT or NMTT-containing antibiotics cause no hypoprothrombinemia even in partially nephrectomized rats when they are fed an ordinary diet containing vitamin K, but these compounds enhance the manifestation of hypoprothrombinemia in vitamin K deficiency. Further renal failure promotes the manifestation by increasing drug concentration in the blood. However, platelet aggregation in these animals is not significantly affected at the doses examined.     

Bioavailability of vitamin C from mashed potatoes and potato chips after oral administration in healthy Japanese men

Potato (Solanum tuberosum) tubers contain vitamin C (VC) and commercial potato chips have more VC content per wet weight by dehydration during frying. However, intestinal absorption of VC from orally ingested potatoes and its transfer to the blood remains questionable. The present study was designed to determine whether the dietary consumption of potatoes affects VC concentration in plasma and urinary excretion of VC in human subjects. After overnight fasting, five healthy Japanese men between 22 and 27 years of age consumed 87 g mashed potatoes and 282 g potato chips. Each portion contained 50 mg of VC, 50 mg VC in mineral water and mineral water. Before and after a single episode of ingestion, blood and urine samples were collected every 30 min or 1 h for 8 h. When measured by subtraction of the initial baseline value before administration of potatoes from the values measured throughout the 8 h test period, plasma VC concentrations increased almost linearly up to 3 h. Subsequently, the values of potato-fed subjects were higher than those of water, but did not differ significantly from those of VC in water (P = 0·14 and P = 0·5). Less VC tended to be excreted in urine during the 8 h test than VC in water alone (17·0 (sem 7·5) and 25·9 (sem 8·8) v. 47·9 (sem 17·9) μmol/mmol creatinine). Upon human consumption, mashed potatoes and potato chips provide VC content that is effectively absorbed in the intestine and transferred to the blood. Clearly, potatoes are a readily available source of dietary VC.     

Time course of vitamin C distribution and absorption after oral administration in SMP30/GNL knockout mice

Objective

Because vitamin C (VC) has multiple metabolic and antioxidant functions, we investigated the movement of VC throughout the tissues of senescence marker protein-30 (SMP30)/gluconolactonase (GNL) knockout (KO) mice.

Methods

SMP30/GNL KO mice, which cannot synthesize VC in vivo, were divided into two groups: VC sufficient and VC deficient. Starting at 2 mo of age, both groups had free access to water containing 1.5 and 0.0375 g/L of VC for 1 mo.

Results

The average rate of VC retention in 20 tissues of VC-deficient SMP30/GNL KO mice was only 13.7% of that in VC-sufficient mice. Tissues that retained over 20% of VC were the cerebellum, white fat, testes, eyeballs, and pancreas, and those with less than 5% VC were the kidneys and heart. These results clearly indicate the different VC retention capacities among tissues. Next, we examined the time course of VC distribution and absorption in VC-deficient SMP30/GNL KO mice. After oral VC administration, VC content in the liver and kidney peaked at 3 h and then decreased. VC content in the lungs, adrenal glands, skin, white fat, and pancreas peaked at 6 h and in the cerebellum, cerebrum, skeletal muscles, eyeballs, thyroid gland, and testes at 12 h.

Conclusion

In this study, we found that exogenous VC administered orally in VC-deficient SMP30/GNL KO mice was distributed at distinctly different rates within individual tissues. The SMP30/GNL KO mice used in this study are a useful animal model that provides unique opportunities for investigating VC movement and metabolism in the entire body.     

The role of PRMT1 in EGFR methylation and signaling in MDA-MB-468 triple-negative breast cancer cells

Background

Epidermal growth factor receptor (EGFR) is often overexpressed in triple-negative breast cancer (TNBC). However, clinical studies have shown that therapies against EGFR are not effective in patients with TNBC. Recently, it has been reported that arginine 198/200 in EGFR extracellular domain is methylated by PRMT1 and that the methylation confers resistance to EGFR monoclonal antibody cetuximab in colorectal cancer cells. To explore a potential mechanism underlying intrinsic resistance to anti-EGFR therapy in TNBC, we investigated the role of PRMT1 in EGFR methylation and signaling in MDA-MB-468 (468) TNBC cells.

Methods

We knocked down PRMT1 in 468 cells by shRNA, and subjected the cell lysates to Western blot analysis to examine EGFR activation and its downstream molecules. We also evaluated cell proliferation and sphere formation of PRMT1-knockdown cells. Finally, we examined the effects of pan-PRMT inhibitor, AMI-1, on cetuximab by colony formation and soft agar assays.

Results

EGFR methylation and activity was significantly reduced in PRMT1-knockdown cells compared to the parental cells. Knockdown of PRMT1 also reduced cell proliferation and sphere formation. Moreover, AMI-1 sensitized 468 cells to cetuximab.

Conclusion

The results indicate that PRMT1 is critical for EGFR activity in 468 cells. Our data also suggest that inhibition of PRMT1 sensitizes TNBC cells to cetuximab. Thus, inhibition of PRMT1 may be an effective therapeutic strategy to overcome intrinsic resistance to cetuximab in TNBC.

     

Expression of gremlin1 in gastric cancer and its clinical significance

As an antagonist of bone morphogenetic proteins (BMPs), 2, 4 and 7, gremlin1 plays a role in regulating organogenesis, tissue differentiation and angiogenesis. However, there is little information regarding gremlin1 in gastrointestinal cancer. We attempted to clarify how gremlin1 expression affects the clinical features and biological properties of gastric cancer. A total of 232 gastric cancer patients who received R0 gastrectomy at Kagoshima University Hospital were enrolled. Gremlin1 expression in gastric cancer was detected by immunohistochemical and western blotting methods. Correlations between clinicopathological parameters and gremlin1 expression were analyzed. Gremlin1 was identified in the cytoplasm and nucleus of all gastric cancer cell lines and some regions of surgical specimens of gastric cancer. One hundred and seventeen of the 232 patients (50.4%) were classified as gremlin1-positive based on gremlin1 expression. Gremlin1 positivity was correlated with shallower tumor depth, smaller tumor size, less nodal involvement and vessel invasion (p < 0.05). The 5-year survival rate of the gremlin1-positive group was 81%, which was significantly higher than the gremlin1-negative group (p < 0.01). Multivariate analysis revealed that gremlin1 was not selected as an independent prognostic marker. Gremlin1 expression in gastric cancer may be a useful prognostic marker that is involved with the BMP signaling pathway. Furthermore, gremlin1 may have clinical use as a diagnostic and treatment tool.     

Genetic alterations in ulcerative colitis-associated neoplasia focusing on APC, K-ras gene and microsatellite instability.

The status of genetic alterations in ulcerative colitis (UC)-associated neoplasia (UCAN) was investigated focusing on microsatellite instability (MSI) which is seen in a certain fraction of colorectal carcinomas, and adenomatous polyposis coli (APC) gene and K-ras gene, in which mutations occur in the early stage of sporadic colorectal tumorigenesis. Thirty-one UCAN from 15 UC patients who had undergone colorectal resection at our institution were investigated. There were 8 lesions of invasive carcinoma, 15 high-grade dysplasia (HGD) and 8 low-grade dysplasia (LGD). DNA was extracted from each neoplastic lesion and corresponding non-neoplastic tissue by a microdissection method. MSI status at 9 microsatellite loci, loss of heterozygosity (LOH) at the APC locus, and K-ras codon 12 point mutation were examined. As for MSI, 4/31 (13%) UCAN (carcinoma: 1/8 (13%), HGD: 2/15 (13%), LGD: 1/8 (13%)) were MSI-high (3 or more unstable loci) and 12/31 (39%) UCAN (carcinoma: 3/8 (38%), HGD: 6/15 (40%), LGD: 3/8 (38%)) were MSI-low (1 or 2 unstable loci). LOH at the APC locus was not found in 9 UCAN from 6 informative (heterozygous) cases. The K-ras mutation rate of UCAN was 3/31 (9.7%) (carcinoma: 2/8 (25%), HGD: 1/15 (7%) and LGD: 0/8). MSI is relatively common in UCAN and is present at the early stage of tumorigenesis of UCAN, while the involvement of genetic alterations of the APC gene and K-ras gene is small. MSI may be one of the mechanisms of the increased neoplastic risk in UC, and UCAN may develop through a different carcinogenic pathway from sporadic carcinomas.     

Observation of occlusal force in prosthetic crown cementings

The method of pressure force in crown cementing was examined. Continuous occlusal force was always supported by the patients' personal occlusal force in cementing crowns. We found that continuous occlusal force continuously decreased as the occlusal force increased, and the decreasing morphologies were classified into four types, 'Rapid decrease', 'Step-wise decrease', 'Intermediate decrease' and 'Gradual decrease'.     

Salvage Gastrectomy Following a Combination of Biweekly Paclitaxel and S-1 for Stage IV Gastric Cancer

Background and aim  We investigated the clinical benefits of salvage gastrectomy for stage IV gastric cancer patients whose distant lesions showed complete response after chemotherapy. Methods  We enrolled 18 stage IV gastric cancer patients whose distant metastases had disappeared or were controlled by a combination of biweekly paclitaxel (PTX) and S-1. After chemotherapy, these patients received gastrectomy with lymph node dissection. The postoperative outcome was analyzed with respect to both the histological effects of chemotherapy and tumor behavior. Results  Of the 18 patients, 8 had distant lymph node metastases, 9 had peritoneal dissemination, and five had multiple liver metastases prior to chemotherapy. Fourteen patients received curative surgery (R0). No severe postoperative complications were encountered. Pathological evaluation revealed grade 3 and grade 2 tumor regression in the primary lesion in one and five patients, respectively, and grade 3 and grade 2 tumor regression in the lymph nodes in one and six patients, respectively. Univariate analysis of the patients’ prognosis identified R number, gross tumor type, histological grade of tumor regression, and gender as significant factors. Multivariate analysis showed that only the R number was an independent prognostic factor. Conclusion  R0 salvage gastrectomy following a combination of biweekly PTX and S-1 may have significant clinical efficacy for advanced gastric cancer patients.