Metastasizing intramucosal gastric carcinomas. Well differentiated type and proliferative activity using proliferative cell nuclear antigen and Ki-67

BACKGROUND

Recently, endoscopic surgery for small superficial gastric carcinomas has become increasingly more challenging, and the treatment criteria remain controversial.

METHODS

To examine the metastatic potential of intramucosal gastric cancers (IMGCs), IMGCs with regional lymph node involvement (NI) were compared with IMGCs without regional lymph NI clinicopathologically. To clarify the metastatic behavior of well differentiated adenocarcinoma (W-type), immunohistochemical staining using Ki-67 and proliferating cell nuclear antigen (PCNA) monoclonal antibodies were performed.

RESULTS

Of the 943 lesions with IMGC, 21 (2.2%) were NI on histologic examination. There was no significant difference between the macroscopic classification and the incidence of NI. The sizes of the IMGCs with NI (median, 4.3 cm) were significantly larger than the IMGCs without NI (median, 2.4 cm). Among the histologic grades classified according to the predominant features, the incidence of NI in poorly differentiated adenocarcinoma (P-type) (12/304, 3.9%) was significantly higher than that in well differentiated (W-type) (6/489, 1.2%). Besides the 12 P-type IMGCs, 6 well and moderately differentiated type IMGCs contained some poorly differentiated components, totaling 18 IMGCs (86%) that were either mainly or partially P-type. Among the W-type IMGCs, the mean values of the Ki-67 and PCNA labeling indices (LI) for IMGCs with NI (Ki-67, 47.5%; PCNA, 58.3%) were higher than those of the 25 randomly selected IMGCs without NI (Ki-67, 39.2%; PCNA, 39.9%).

CONCLUSIONS

The potential for NI in IMGCs seems to be related closely to tumor size, the presence of poorly differentiated components, and, particularly in the W-type IMGC, the LI that are demonstrated immunohistochemically with Ki-67 and/or PCNA.

Risk factors related to liver metastasis in colorectal carcinoma: a multivariate analysis of clinicopathologic and immunohistochemical variables

Specimens from 48 consecutive patients undergoing surgery for colorectal carcinoma and having synchronous or metachronous liver metastases (Group 1) and those from 52 consecutive patients who had no evidence of hepatic metastases within at least 5 year after colorectal resection (Group 2) were selected and compared using a multiple logistic regression analysis. A multivariate analysis using a stepwise logistic regression revealed six independent risk factors significantly related to hepatic metastases. In addition, the following logistic regression model was obtained from this analysis. P = exp a/(1 + exp a): a = 3.524(SM-V) + 2.731(Ex-V) + 2.718(E/M) + 2.562(Lo) + 1.858(p53) + 1.941(HIR) - 4.397, where P is the probability of hepatic metastasis given six independent risk factors (E/M, Ex/M ratio; Lo, location; HIR, host inflammatory cell reaction). When the estimated probability "P" in the above logistic regression model is more than 0.55 after an examination of surgical specimens, we must consider adjuvant chemotherapy and closely monitor the patient to ensure early detection of hepatic metastases.

Proliferating cell nuclear antigen, plasma fibronectin, and liver regeneration rate after seventy percent hepatectomy in normal and cirrhotic rats

BACKGROUND

The difference in liver regeneration rate in relation to proliferating cell nuclear antigen (PCNA) and plasma fibronectin level in the cirrhotic and control liver after 70% hepatectomy were examined in the rat.

METHODS

Liver cirrhosis was induced by intraperitoneal injection of thioacetamide for 12 weeks; rats without thioacetamide administration served as controls. On the day before and days 1, 2, 3, and 7 after 70% hepatectomy, PCNA labeling index of hepatocyte, plasma fibronectin level, and percentage of the initial liver weight were determined.

RESULTS

Liver regeneration rate as expressed by percent of initial liver weight was impaired in the cirrhotic liver, and significantly lower regeneration rate was observed on days 3 and 7 after hepatectomy in the cirrhotic rats as compared with controls. PCNA labeling index was higher in the cirrhotic liver before hepatectomy. Little change of PNA labeling index was observed in the cirrhotic liver, although the index increased significantly in the control liver; significantly higher values were observed on days 1, 2, and 3, with the maximal value on day 2 after hepatectomy. The plasma fibronectin level was significantly lower in the cirrhotic rat before and after hepatectomy.

CONCLUSIONS

The results show that liver regeneration is impaired in the cirrhotic liver associated with little activation of PCNA and with lower plasma fibronectin level.

Metabolic activation of CPT-11, 7-ethyl-10-[4-(1-piperidino)-1- piperidino]carbonyloxycamptothecin, a novel antitumor agent, by carboxylesterase

We measured the plasma concentrations of 7-ethyl-10-[4-(1-piperidino)-1- piperidine]carbonyloxycamptothecin (CPT-11) and the active metabolite 7-ethyl-10-hydroxycamptothecin (SN-38), after treatment with CPT-11 to rats pretreated with bis-p-nitrophenylphosphate (BNPP) which is a specific inhibitor of carboxylesterase, and non-pretreated rats. The plasma level of SN-38 was decreased in the BNPP-pretreated group compared with these of non-pretreated group, indicating that the esterase involved in CPT-11 metabolism is a carboxylesterase. We also characterized the molecular species of carboxylesterase involved in CPT-11 metabolism using enzyme preparations purified from liver microsomes. Thirteen carboxylesterase isozyme activities towards CPT-11 were compared and guinea pig GLP1 was found to have the highest activity, while human HU1 isozyme had relatively lower activity than those of animal species. In studies on the kinetic parameters of the hydrolysis of CPT-11 by the purified carboxylesterase isozymes the highest Vmax value of the isozymes was found in human HU1 and the smallest was seen in rat RL1. The Vmax/Km for RL1 showed the largest value of 21.7 nmol/mg protein/mM.

Adenosquamous carcinoma of the gallbladder: a clinicopathological, immunohistochemical and flow-cytometric study of twenty cases

Twenty patients (7.4%) with adenosquamous carcinoma of the gallbladder were selected from 271 surgically resected gallbladder cancers. The 20 patients were composed of 8 men and 12 women with a mean age of 66.9 years. Histologically, all twenty tumors showed an abrupt transition between the adenocarcinoma (AC) and squamous cell carcinoma (SCC) areas, and well differentiated AC was also found in the peripheral area of the tumor. A histochemical and immunohistochemical study using alcian blue, periodic acid-Schiff, cytokeratins, involculin and tissue polypeptide antigen disclosed a different nature of the two components. DNA heterogeneity between the components was detected in 5 of 7 cases by flow cytometry. The positive rate of immunostaining for proliferating cell nuclear antigen in the SCC areas (mean 20.55%) was larger than that of the AC areas (mean 11.40%) (P = 0.0029), which indicated that the SCC areas had a greater proliferative capacity than AC areas. These results suggest that the SCC component of adenosquamous carcinoma of the gallbladder arose by a stepwise molecular progression of the pre-existing AC. Furthermore, the prognosis of adenosquamous carcinomas of the gallbladder (mean survival: 10 months) in the advanced stage (pTNM 2-4) was less favorable than those of papillary and well differentiated AC (mean survival: 99 months and 86 months) (P < 0.0001).

Thyroid gland metastasis from renal cell carcinoma masquerading as nodular goitre

Renal cell carcinoma metastasizing to the thyroid gland, in a 72 year old Japanese woman, is reported. The patient had undergone a left radical nephrectomy for renal cell carcinoma 3 months prior to the present operation. The patient noticed a nodular goitre but there was no evidence of any systemic spread of renal cell carcinoma. The histopathologic diagnosis, from a left lobectomy of the thyroid gland, was thyroid gland metastasis from renal cell carcinoma in adenomatous goitre. Clinical manifestation of thyroid gland metastasis from renal cell carcinoma, with no evidence of systemic involvement, is seen rarely. A case is reported and the condition discussed briefly.

Small-cell carcinoma combined with adenocarcinoma of the gallbladder. A case report with immunohistochemical and flow cytometric studies

A small-cell carcinoma combined with adenocarcinoma of the gallbladder was detected in a 71-year-old Japanese woman. A nodular mass measuring 4.0 x 5.0 cm was located in the fundus of the gallbladder, in which a tiny depressed lesion measuring 2 mm in diameter was macroscopically and stereomicroscopically observed. Histologically, the depressed area revealed small-cell carcinoma that consisted of atypical cells with small, round to oval nuclei and scanty cytoplasm and was surrounded by ordinary well-differentiated adenocarcinoma. Immunohistochemically, the tumor cells in an adenocarcinomatous area were diffusely positive for carcinoembryonic antigen and showed an interspersed positivity to serotonin and gastrin, while the tumor cells in the small-cell carcinoma area were negative for both antigens. The nuclear DNA content of the tumor cells of both components was aneuploid; however, the first G0/G1 peak of the small-cell carcinoma was much smaller than that of the adenocarcinoma. These results indicated that the tumor revealed a divergence in functional differentiation, and this feature suggested an initial phase of composite small-cell carcinoma and adenocarcinoma in the gallbladder.

Hepatoid adenocarcinoma of the stomach. A clinicopathologic and immunohistochemical analysis

BACKGROUND

The clinicopathologic and immunohistochemical features of the primary gastric hepatoid adenocarcinomas still remain unclear.

METHODS

The authors evaluated 28 hepatoid adenocarcinomas (HC) of the stomach on the basis of characteristic histologic features resembling hepatocellular carcinoma, which were selected from the 7200 cases of primary gastric carcinoma in their files. Additionally, 22 alpha-fetoprotein (AFP)-positive adenocarcinomas without hepatoid features (APC) were also selected.

RESULTS

The HC cases fell into the following two groups: HC with AFP-positive tumor cells (Group 1; 15 cases) and HC without AFP-positive cells (Group 2; 13 cases). Histologically, the glycogen granules and hyaline globules were common features in HC. The incidence of a venous invasion of HC (Groups 1 and 2) was higher than that of APC (Group 3). There were no significant differences among the three groups regarding clinical features, macroscopic features, and the incidence of lymphatic permeation. An immunohistochemical study showed that HC had differentiation into various directions. As for the advanced carcinomas, the 5-year survival rates of patients with HC (Groups 1 and 2) and those with APC (Group 3) were 11.9% (21.4%, 8.3%) and 38.2%, respectively. The prognosis of Group 1 was similar to that of Group 2, but was poorer than that of Group 3.

CONCLUSIONS

The findings suggested that HC, as shown by its characteristic histologic features, had a poor prognosis whether producing AFP or not, and that HC should therefore be distinguished from AFP-positive carcinoma without hepatoid features.

Hepatoid adenocarcinoma of the stomach. A clinicopathologic and immunohistochemical analysis

BACKGROUND

The clinicopathologic and immunohistochemical features of the primary gastric hepatoid adenocarcinomas still remain unclear.

METHODS

The authors evaluated 28 hepatoid adenocarcinomas (HC) of the stomach on the basis of characteristic histologic features resembling hepatocellular carcinoma, which were selected from the 7200 cases of primary gastric carcinoma in their files. Additionally, 22 alpha-fetoprotein (AFP)-positive adenocarcinomas without hepatoid features (APC) were also selected.

RESULTS

The HC cases fell into the following two groups: HC with AFP-positive tumor cells (Group 1; 15 cases) and HC without AFP-positive cells (Group 2; 13 cases). Histologically, the glycogen granules and hyaline globules were common features in HC. The incidence of a venous invasion of HC (Groups 1 and 2) was higher than that of APC (Group 3). There were no significant differences among the three groups regarding clinical features, macroscopic features, and the incidence of lymphatic permeation. An immunohistochemical study showed that HC had differentiation into various directions. As for the advanced carcinomas, the 5-year survival rates of patients with HC (Groups 1 and 2) and those with APC (Group 3) were 11.9% (21.4%, 8.3%) and 38.2%, respectively. The prognosis of Group 1 was similar to that of Group 2, but was poorer than that of Group 3.

CONCLUSIONS

The findings suggested that HC, as shown by its characteristic histologic features, had a poor prognosis whether producing AFP or not, and that HC should therefore be distinguished from AFP-positive carcinoma without hepatoid features.

Hepatoid adenocarcinoma of the stomach. A clinicopathologic and immunohistochemical analysis

BACKGROUND

The clinicopathologic and immunohistochemical features of the primary gastric hepatoid adenocarcinomas still remain unclear.

METHODS

The authors evaluated 28 hepatoid adenocarcinomas (HC) of the stomach on the basis of characteristic histologic features resembling hepatocellular carcinoma, which were selected from the 7200 cases of primary gastric carcinoma in their files. Additionally, 22 alpha-fetoprotein (AFP)-positive adenocarcinomas without hepatoid features (APC) were also selected.

RESULTS

The HC cases fell into the following two groups: HC with AFP-positive tumor cells (Group 1; 15 cases) and HC without AFP-positive cells (Group 2; 13 cases). Histologically, the glycogen granules and hyaline globules were common features in HC. The incidence of a venous invasion of HC (Groups 1 and 2) was higher than that of APC (Group 3). There were no significant differences among the three groups regarding clinical features, macroscopic features, and the incidence of lymphatic permeation. An immunohistochemical study showed that HC had differentiation into various directions. As for the advanced carcinomas, the 5-year survival rates of patients with HC (Groups 1 and 2) and those with APC (Group 3) were 11.9% (21.4%, 8.3%) and 38.2%, respectively. The prognosis of Group 1 was similar to that of Group 2, but was poorer than that of Group 3.

CONCLUSIONS

The findings suggested that HC, as shown by its characteristic histologic features, had a poor prognosis whether producing AFP or not, and that HC should therefore be distinguished from AFP-positive carcinoma without hepatoid features.

Study on high-strength plastic teeth. Tooth discoloration

Conventional plastic teeth (CV teeth) are inferior to porcelain teeth in maintaining an adequate esthetic appearance with wear and discoloration, and thus have a shorter period of durability. Recently, high-strength plastic teeth (HS teeth) have been developed and applied to overcome the wear problems of CV teeth. Since HS teeth made of hard resin are still susceptible to staining with pigments, it has been observed that the esthetics of removable partial dentures made from such plastic teeth are gradually impaired in many patients. To investigate the susceptibility of HS teeth to pigments, we conducted an in vitro study by immersing three types of artificial teeth in three coloring liquids. It was found that the HS teeth tended to be less susceptible to the test pigments than the CV teeth to various degrees. In contrast, they showed markedly stronger susceptibility to the pigments than porcelain teeth. For all three artificial tooth types, daily tooth cleaning with an ultrasonic vibrator had a tendency to reduce the coloration in comparison with their counterparts without ultrasonic cleaning.

Vimentin-positive gastric carcinomas with rhabdoid features. A clinicopathologic and immunohistochemical study

We studied 71 patients with solid-type gastric adenocarcinoma selected from 5,437 surgically resected specimens during the period from 1975 to 1988; six had vimentin-positive adenocarcinomas, and five of these were advanced. One was at an early stage. All six tumors showed the same histologic features and had either a diffuse or alveolar arrangement, with tumor cells having either poor or no cohesiveness. Many tumor cells were round to polygonal, with eosinophilic or clear cytoplasm and large, eccentric vesicular nuclei, as seen in malignant rhabdoid tumors of the kidney. In all cases, the cytoplasm showed coexpression of vimentin and cytokeratin as revealed by double immunostaining. Four of the five cases with advanced carcinoma died of the disease 1 to 6 months after surgery. The cases with vimentin-positive tumors had significantly poorer prognoses than those with vimentin-negative tumors. We also studied adenocarcinomas of various histologic types randomly selected from our file (160 intestinal type and 69 diffuse type of Lauren) but failed to detect any vimentin positive ones. These results indicate that vimentin is expressed in some of the solid-type adenocarcinomas, which have a poor prognosis, and indicating that rhabdoid-like cells may be found in a variety of adenocarcinomas of the stomach.

Carcinoma of the ampulla of Vater

A consecutive series of 36 Japanese patients with ampullary carcinoma who underwent a pancreatoduodenectomy at the Department of Surgery I, Kyushu University Hospital during the past 20 years were reviewed clinicopathologically to study prognostic factors. A univariate generalized Wilcoxon test showed that preoperative serum carcino-embryonic antigen (CEA) concentration, venous invasion, lymphatic permeation and perineural invasion were significant parameters. A multivariate Cox regression analysis showed that venous invasion was the only significant variable. In a sequential serum CEA follow up of 10 patients, an elevation of serum CEA levels was seen to correspond to the clinical development of a recurrence in six, while a high concentration of serum CEA was not evident despite the clinical manifestation of a recurrence in two, and serum CEA levels remained within the normal limits with no evidence of a recurrence in two others. According to the death certificates of 15 patients, where an exact site of metastasis was available, 11 died from liver metastasis, three from lung metastasis and one from peritoneal dissemination. These findings support the theory that a histologic invasion of the venous space is an independent prognostic factor and close attention should be paid to any signs of haematogenous metastasis, such as to the liver and lung, as well as to a serial serum CEA follow up.

Study on the castability of Co-Cr alloy for cast plates. Part 3: Effects of alloy fusion temperature and the heating temperature of the cast ring

Co-Cr alloy is used more frequently than Ni-Cr alloy as a non-precious alloy for cast plates in Japan. However, since the melting temperature of Co-Cr alloy is very high, about 1300 degrees C, and since it oxidizes easily, a vacuum-pressure casting machine capable of melting this alloy in a reduced atmosphere has recently been developed. Using this machine, the effects of fusion temperature and the heating temperature of the cast ring on the Co-Cr alloy were studied. It was found that in the vacuum-pressure casting method, both the fusion temperature of the Co-Cr alloy and the heating temperature of the cast ring had a significant effect (p < 0.01) on the castability of the Co-Cr alloy.

Are secondary bile acids in choledochal cysts important as a risk factor in biliary tract carcinoma?

Since secondary bile acids have mutagenic potency and choledochal cyst patients with or without cyst-enterostomy have a high risk of developing bile duct carcinoma, we examined the hypothesis that secondary bile acids are elevated in the choledochal cyst and possibly cause biliary tract carcinoma. Eleven choledochal cyst patients with or without previous cyst-enterostomy or biliary tract carcinoma, seven patients with biliary tract carcinoma not associated with choledochal cyst and five patients with cholecystolithiasis were examined. Samples were directly needle aspirated from the cyst or by cannulating a tube into the common bile duct through the cystic duct. The concentrations of each bile acid in these samples were quantified by gas-liquid chromatography and compared. Neither the relative composition nor the absolute concentration of secondary bile acids (deoxycholic acid, lithocholic acid) elevated in patients with choledochal cyst compared with the values in the non-choledochal cyst patients with or without biliary tract carcinoma. The presence of biliary tract carcinoma or previous cyst-enterostomy did not affect the concentrations of secondary bile acids. The results suggest that the factor other than secondary bile acids can be primarily responsible for the high risk of bile duct carcinoma in patients with choledochal cyst.

Inhibition of beta-glucuronidase by natural glucuronides of kampo medicines using glucuronide of SN-38 (7-ethyl-10-hydroxycamptothecin) as a substrate

1. 7-Ethyl-10-[4-(piperidino)-1-piperidino] carbonyloxycamptothecin (CPT-11), a potent anticancer agent currently under development for clinical use, is metabolized in vivo to 7-ethyl-10-hydroxycamptothecin (SN-38), which is subsequently conjugated to 7-ethyl-10-hydroxycamptothecin glucuronide (SN-38-glucuronide). The SN-38-glucuronide was hydrolysed by beta-glucuronidase from E. coli to aglycones and glucuronic acid. 2. Four purified natural glucuronides including baicalin, wogonoside, luteolin-3'-glucuronide, and glycyrrhizin, inhibited beta-glucuronidase using SN-38-glucuronide as substrate. The inhibition potencies of these natural glucuronides toward beta-glucuronidase were similar to that of saccharic acid 1,4-lactone. 3. These results indicate that plant materials of Kampo (Japanese herbal) medicines containing these glucuronides could be used in vivo to decrease the enterohepatic circulation of SN-38 and possibly that of other drugs.

Wear of denture teeth by use of metal plates. Part 3: Abrasive wear of posterior teeth and wear of opposing metal plates

An in vitro evaluation of abrasive wear resistance of high-strength denture (HS) teeth and wear of metal plates (Pd alloy) on the opposing side was conducted. A total of 8 types of teeth were used in the experiments including 3 types of HS teeth, 3 types of conventional plastic denture (PL) teeth, porcelain teeth and metal teeth (Pd alloy). Sliding-induced wear tests were conducted by sliding these teeth over the metal plates. Abrasive wear resistance of the teeth was evaluated in terms of wear depth and weight loss. A comparison of wear depth showed that the abrasive wear resistance of HS teeth was 4.7 times that of PL teeth, 0.7 times that of porcelain teeth and 8.3 times that of metal teeth. Weight loss showed that the abrasive wear resistance of HS teeth was 3.3 times that of PL teeth, 0.2 times that of porcelain teeth and 11.4 times that of metal teeth. The weight loss of the metal plates was minimal when they slid over HS teeth, but increased in the order PL teeth, porcelain teeth and metal teeth.

Wear of denture teeth by use of metal plates. Part 2: Abrasive wear of posterior teeth

An in vitro study was conducted to evaluate the abrasive wear resistance of high-strength denture teeth (HS teeth). Eight types of specimen were used in the experiments; 3 types of HS teeth, 3 types of conventional plastic denture teeth (PL teeth), porcelain teeth and metal teeth. Sliding-induced wear tests were conducted by sliding the samples on a metal plate. The abrasive wear resistance of the samples was evaluated in terms of wear depth, weight loss and SEM observation. Comparison of wear depth showed that abrasive wear resistance of HS teeth was 4.7 times that of PL teeth, 0.7 times that of porcelain teeth and 8.3 times that of metal teeth. In terms of weight loss, the corresponding values were 3.3-fold, 0.2-fold and 11.4-fold, respectively.

Carcinoid tumor of the pancreas with obstructive pancreatitis

A case of primary pancreatic enterochromaffin cell (EC cell) carcinoid tumor in a 66-yr-old Japanese man is presented. The markedly dilated main pancreatic duct was noticed at the time of an incidental ultrasonogram during hospitalization for diabetes mellitus. Endoscopic retrograde pancreatography showed stenosis of the main pancreatic duct at the body of the pancreas and dilated pancreatic ducts distal to the obstruction. A distal pancreatectomy was performed, together with splenectomy. Macroscopically, the main pancreatic duct was compressed by a fibrous mass around the duct, and the pancreatic ducts distal to the tumor were markedly dilated. Histologically, the tumor was composed of uniform round cells, proliferating in small nests or trabeculae. The tumor cells were strongly positive with both Grimelius and Fontana-Masson stains. The immunohistochemical study disclosed the tumor cells to be positive for serotonin and chromogranin. This is a rare case of primary pancreatic EC cell carcinoid tumor with obstructive pancreatitis.

Pathology of carcinoma of the gallbladder

A clinicopathologic study of 40 cases of carcinoma of the gallbladder is presented. Twenty-six cases resected were assessed retrospectively with respect to the operative procedures employed and the results based on the pathologic findings from the resected specimens. The relationship between clinical features, macroscopic forms of tumor, histological types, liver invasion, and lymph node metastasis were investigated. Papillary, papillary infiltrative and nodular forms were classified as either papillary adenocarcinoma or well-differentiated tubular adenocarcinoma and invasion of the liver and lymph node metastasis were rare. Frequent lymph node metastasis was encountered in the nodular infiltrative form and invasion of the liver was frequently present in the infiltrative form. Invasion of the liver, lymph node metastasis, and the presence of gallstones were less frequent in papillary adenocarcinoma. In contrast, moderately-differentiated tubular adenocarcinoma frequently had lymph node metastasis. Invasion of the liver and lymph node metastasis were, however, present regardless of the histologic types and were more related to the extent of subserosal involvement present. A female preponderance was noted in poorly-differentiated adenocarcinoma. The main reasons for surgery being limited to exploratory laparotomy only or palliative procedures included carcinoma infiltration into the hepatoduodenal ligament, carcinoma extension to the neighboring structures, multiple liver metastases, peritoneal dissemination, large liver invasion, and multiple metastases to the paraaortic lymph nodes.

Distribution of mouse interferon-beta in normal and brain tumour-bearing mice

The distribution of 125I-labelled recombinant mouse interferon-beta (rMuIFN-beta) in normal and glioma (203 glioma) bearing mice was studied by radioassay and macro-autoradiography at 15 and 30 min after a single intravenous injection. The level of rMuIFN-beta in the spleen was about 20-fold higher than in serum. Concentrations higher than the serum level was detected in the lung, liver and kidney. The concentration of rMuIFN-beta in the brain was 8% of the serum level and the concentration in the glioma 30 min after administration was about 10-fold higher than in normal mouse brain. Macro-autoradiographic study demonstrated a wide distribution range and selective uptake in glioma tissue. Furthermore, we found that mouse gliomas were sensitive to mouse IFN-beta. Our findings demonstrate that in the mouse glioma model, intravenously administered interferon reaches the tumour.

Wear of artificial denture teeth by use of toothbrushes. Part 1: Abrasive wear of anterior teeth

High-strength denture teeth (HS teeth) were developed in order to improve the hardness and wear resistance of conventional plastic denture teeth (PL teeth), while retaining their feature of easy occlusal adjustment. The objective of this study was to evaluate the abrasive wear resistance of HS teeth. We conducted wear tests and measured surface roughness using six types of anterior artificial teeth, i.e., three types of HS teeth and three types of PL teeth, the latter serving as the control. The results of the toothbrush abrasion test revealed that the HS teeth had about 5 times greater wear resistance than the PL teeth. It was also found that the type of artificial teeth and the number of abrasive wear-testing strokes had a significant (P less than 0.05) influence on the surface roughness of artificial teeth.