Pathogenesis of selective damage of granule cell layer in cerebellum of rats exposed to methylmercury

Granule cell-selective toxicity of methylmercury in the cerebellum is one of the main unresolved issues in the pathogenesis of Minamata disease. Rats were orally administered methylmercury chloride (10 mg/kg/day) for 5 consecutive days, and their brains were harvested on days 1, 7, 14, 21, or 28 after the last administration for histological examination of the cerebellum. It was found that methylmercury caused a marked degenerative change to the granule cell layers but not to the Purkinje cell layers. The generative change of the granule cell layer was due to cell death, including apoptosis, which occurred at day 21 and beyond after the methylmercury administration. Meanwhile, cytotoxic T-lymphocytes and macrophages had infiltrated the granule cell layer. Additionally, granule cells are shown to be a cell type susceptible to TNF-α. Taken together, these results suggest that methylmercury causes small-scale damage to granule cells, triggering the infiltration of cytotoxic T-lymphocytes and macrophages into the granule cell layer, which secrete tumor necrosis factor-α (TNF-α) to induce apoptosis in granule cells. This chain is established based on the susceptibility of granule cells to methylmercury, the ability of cytotoxic T lymphocytes and macrophages to synthesize and secrete TNF-α, and the sensitivity of granule cells to TNF-α and methylmercury. We propose to call the pathology of methylmercury-induced cerebellar damage the "inflammation hypothesis."

[A Case of Advanced Rectal Cancer Resected Successfully after Induction Chemotherapy with Modified FOLFOX6 plus Panitumumab]

We report a case of advanced colon cancer that was effectively treated with mFOLFOX6 plus panitumumab combination chemotherapy. The patient was a 54-year-old man who had type 2 colon cancer of the rectum. An abdominal CT scan demonstrated rectal cancer with bulky lymph node metastasis and 1 hepatic node (rectal cancer SI [bladder retroperitoneum], N2M0H1P0, cStage IV). He was treated with mFOLFOX6 plus panitumumab as neoadjuvant chemotherapy. After 4 courses of chemotherapy, CT revealed that the primary lesion and regional metastatic lymph nodes had reduced in size (rectal cancer A, N1H1P0M0, cStage IV). Anterior rectal resection with D3 nodal dissection and left lateral segmentectomy of the liver was performed. The histological diagnosis was tubular adenocarcinoma (tub2-1), int, INF a, pMP, ly0, v0, pDM0, pPM0, R0. He was treated with 4 courses of mFOLFOX6 after surgery. The patient has been in good health without a recurrence for 2 years and 5 months after surgery. This case suggests that induction chemotherapy with mFOLFOX6 plus panitumumab is a potentially effective regimen for advanced colon cancer.

[A case of emergency resection of a giant gastrointestinal stromal tumor of the stomach associated with hemorrhagic shock]

We report a case of emergency resection of a giant gastrointestinal stromal tumor of the stomach associated with hemorrhagic shock. A 79-year-old woman was admitted to our hospital because of massive hematemesis. Laboratory analysis revealed a hemoglobin level of 6.5 g/dL. Abdominal computed tomography (CT) and upper gastrointestinal endoscopy revealed a submucosal tumor, 12 cm in diameter, in the fornix of the stomach. As a Dieulafoy-like lesion was present, we attempted coagulation hemostasis in the exposed blood vessels. Endoscopic hemostasis was not successful. The patient went into hemorrhagic shock. Emergency surgery was performed: total gastrectomy with distal pancreatosplenectomy. The resected specimen measured 10×12×7 cm and was hard. Immunohistologically, the tumor was positive for c-kit and CD34 and negative for alpha smooth muscle actin (αSMA), desmin, and S-100. Histological examination revealed that the patient had a high-risk gastrointestinal stromal tumor of the stomach with no nodal metastasis. The postoperative course was uneventful and the patient has remained alive without recurrence for 4 years.

The cytotoxicity of methylmercury in human microvascular endothelial cells and pericytes in culture

Methylmercury is an environmental neurotoxin that induces severe neurological damage in the brain of humans and animals. The main pathological characteristic of methylmercury neurotoxicity is the location of the damage; lesions are localized around the deep sulci and fissures in the cerebral cortex, such as the calcarine fissure, and the granule cell layer of the cerebellum. Since the localization of the damage is suggested to be a result of secondary damage occurring due to edematous change in the white cortex, the toxicity of methylmercury to cells that compose the microvessels--endothelial cells and pericytes--may be important for understanding the neurotoxicity of methylmercury. We investigated the toxicity of methylmercury to human brain microvascular endothelial cells and pericytes using a cell culture system. It was revealed that the toxicity of methylmercury to microvascular cells depends on the cell type and density. It is suggested that vascular tissue is one of the targets of methylmercury toxicity and that this may contribute to the progression of edematous change in the brain. Methylmercury may also be involved in the progression of cardiovascular diseases.

1,635 Endoscopic submucosal dissection cases in the esophagus, stomach, and colorectum: complication rates and long-term outcomes

Background

Endoscopic submucosal dissection (ESD) enables en bloc resection of early gastrointestinal neoplasms; however, most ESD articles report small series, with short-term outcomes performed by multiple operators on single organ. We assessed short- and long-term treatment outcomes following ESD for early neoplasms throughout the gastrointestinal tract.

Methods

We performed a longitudinal cohort study in single tertiary care referral center. A total of 1,635 early gastrointestinal neoplasms (stomach 1,136; esophagus 138; colorectum 361) were treated by ESD by single operator. Outcomes were complication rates, en bloc R0 resection rates, and long-term overall and disease-specific survival rates at 3 and 5 years for both guideline and expanded criteria for ESD.

Results

En bloc R0 resection rates were: stomach: 97.1 %; esophagus: 95.7 %; colorectum: 98.3 %. Postoperative bleeding and perforation rates respectively were: stomach: 3.6 and 1.8 %; esophagus: 0 and 0 %; colorectum: 1.7 and 1.9 %. Intra criteria resection rates were: stomach: 84.9 %; esophagus: 81.2 %; colorectum: 88.6 %. Three-year survival rates for lesions meeting Japanese ESD guideline/expanded criteria were for all organ-combined: 93.4/92.7 %. Five-year rates were: stomach: 88.1/84.6 %; esophagus: 81.6/57.3 %; colorectum: 94.3/100 %. Median follow-up period was 53.4 (range, 0.07–98.6) months. Follow-up rate was 94 % (1,020/1,085). There was no recurrence or disease-related death.

Conclusions

In this large series by single operator, ESD was associated with high curative resection rates and low complication rates across the gastrointestinal tract. Disease-specific and overall long-term prognosis for patients with lesions within intra criteria after curative resection appeared to be excellent.

Suppression of fibroblast growth factor-2 expression: possible mechanism underlying methylmercury-induced inhibition of the repair of wounded monolayers of cultured human brain microvascular endothelial cells

Vascular toxicity is an important feature of the neuropathy induced by methylmercury. Methylmercury does not cause nonspecific cell damage, but rather retards the repair of wounded monolayers of cultured human brain microvascular endothelial cells by inhibiting their proliferation. Since vascular endothelial cell proliferation during the repair process strongly depends on the fibroblast growth factor-2 (FGF-2) system, we investigated the effects of methylmercury on the expression of FGF-2 and related proteins (i.e., FGF receptor 1 and perlecan) in cultured human brain microvascular endothelial cells. Of the mRNAs examined, FGF-2 mRNA expression was significantly lowered by methylmercury in not only wounded monolayers but also dense and sparse cultures of endothelial cells; a lower expression of FGF-2 protein in the cells was confirmed. In addition, exogenous FGF-2 partially abrogated the proliferation-inhibitory effect of methylmercury. The results of this study suggest that suppression of FGF-2 expression is one of the mechanisms underlying the inhibitory effect of methylmercury in damaged endothelial cell monolayers. The FGF-2 system may be one of the important biological systems behind the vascular toxicity of methylmercury.

Arsenite but not arsenate inhibits general proteoglycan synthesis in cultured arterial smooth muscle cells

Epidemiological and experimental studies have suggested that exposure to metalloid arsenic constitutes a risk factor for vascular disease associated with atherosclerosis. Since in atherosclerosis, types of proteoglycans (PGs) present change depending on the stage, we investigated the effect of 2 chemical forms of inorganic arsenic-a trivalent sodium arsenite and a pentavalent sodium arsenate-on the synthesis of PGs in cultured arterial smooth muscle cells. The results indicate that arsenite but not arsenate, at a noncytotoxic level, inhibits general PG synthesis independent of cell density. Arsenite may be one of the chemical forms of inorganic arsenic that influences the PG composition in blood vessel walls during the progression of vascular disorders such as atherosclerosis.

A novel method using cyanobacteria for ecotoxicity test of veterinary antimicrobial agents

The effect of antimicrobial agents for veterinary use on the growth of cyanobacteria was investigated by measuring minimum inhibitory concentration, medium effective concentration (EC50), and no-observed-effect concentration of seven antimicrobial agents for eight cyanobacteria. The results demonstrated that the seven antimicrobial agents, even at low concentrations, inhibited the growth of cyanobacteria. Microcystis aeruginosa and Synechococcus sp. had the highest sensitivity to the antimicrobial agents used in the present study. It is considered that the utilization of cyanobacteria would enable easy and highly sensitive assessment of the toxicity of such chemicals as antimicrobial agents. We suggest that cyanobacteria be used for ecotoxicity test in addition to the hitherto established method that uses green algae.

2'-,5'-Oligoadenylate synthetase response ratio predicting virological response to PEG-interferon-α2b plus ribavirin therapy in patients with chronic hepatitis C

OBJECTIVE

Although all the mechanisms of elimination of hepatitis C virus (HCV) by Interferon (IFN) have not been fully elucidated, the 2'-5'-oligoadenylate (2-5A) system is one of the mechanisms of the antiviral effect of IFN. Consequently, the measurement of 2'-5'-oligoadenylate synthetase (2-5AS) activity could be useful for the evaluation of IFN treatment. This retrospective study was aimed at assessing whether 2-5AS activity functions as a clinical marker of virological response to PEG-interferon-alpha2b (PEG-IFN) plus ribavirin therapy of chronic hepatitis C.

METHODS

The 32 patients included in this study had high viral loads of serum HCV-RNA of genotype 1b with chronic hepatitis C. All the patients received a regimen of PEG-IFN plus ribavirin for 48 weeks, and were then divided into two groups: one group (effective group) with undetectable serum HCV-RNA levels at 24 weeks (n = 22) of therapy, the other group (ineffective group) with persistent presence of HCV-RNA in serum at 24 weeks (n = 10). The 2-5AS activity in serum was measured 2, 8 and 12 weeks before initial administration.

RESULTS

The 2-5AS response ratio (measured value/measured value of baseline 2-5AS) at 2, 8 and 12 weeks after the administration in the effective group was significantly higher than that in the ineffective group.

CONCLUSIONS

These results suggest that the ratio of 2-5AS is closely related to the antiviral effect, and that the measurement of 2-5AS response ratio may be a useful clinical parameter of virological response to PEG-IFN plus ribavirin therapy of chronic hepatitis C.

Flubendiamide, a novel Ca2+ channel modulator, reveals evidence for functional cooperation between Ca2+ pumps and Ca2+ release

Flubendiamide, developed by Nihon Nohyaku Co., Ltd. (Tokyo, Japan), is a novel activator of ryanodine-sensitive calcium release channels (ryanodine receptors; RyRs), and is known to stabilize insect RyRs in an open state in a species-specific manner and to desensitize the calcium dependence of channel activity. In this study, using flubendiamide as an experimental tool, we examined an impact of functional modulation of RyR on Ca2+ pump. Strikingly, flubendiamide induced a 4-fold stimulation of the Ca2+ pump activity (EC50=11 nM) of an insect that resequesters Ca2+ to intracellular stores, a greater increase than with the classical RyR modulators ryanodine and caffeine. This prominent stimulation, which implies tight functional coupling of Ca2+ release with Ca2+ pump, resulted in a marginal net increase in the extravesicular calcium concentration despite robust Ca2+ release from the intracellular stores by flubendiamide. Further analysis suggested that luminal Ca2+ is an important mediator for the functional coordination of RyRs and Ca2+ pumps. However, kinetic factors for Ca2+ pumps, including ATP and cytoplasmic Ca2+, failed to affect the Ca2+ pump stimulation by flubendiamide. We therefore conclude that the stimulation of Ca2+ pump by flubendiamide is mediated by the decrease in luminal calcium, which may induce calcium dissociation from the luminal Ca2+ binding site on the Ca2+ pump. This mechanism should play an essential role in precise control of intracellular Ca2+ homeostasis.

Biodegradation of bisphenol A and disappearance of its estrogenic activity by the green alga Chlorella fusca var. vacuolata

Bisphenol A (BPA) is known as an endocrine disruptor and often is found in landfill leachates. Removal of BPA by green alga, Chlorella fusca, was characterized, because we previously found that various phenols were well removed by this strain, including BPA. Chlorella fusca was able to remove almost all BPA in the concentration range from 10 to 80 microM for 168 h under continuous illumination at 18 W/m2. At the low light intensity of 2 W/m2, 82% of 40 microM BPA was removed, and only 27% was removed in the dark. Moreover, C. fusca could remove 90% of 40 microM BPA under the 8:16-h light:dark condition, which was almost as high as that under the continuous-light condition. The amount of BPA contained in the cells was less than the amount of BPA removed from the medium. Monohydroxybisphenol A was detected as an intermediate of BPA degradation. Moreover, estrogenic activity that originated from BPA in the culture medium also completely disappeared. Based on these results, BPA was finally degraded to compounds having nonestrogenic activity. Therefore, C. fusca can be considered a useful organism to remove BPA from landfill leachates.

Bone mineral density in adult patients with Turner's syndrome: analyses of the effectiveness of GH and ovarian steroid hormone replacement therapies

To analyze the effects of treatments with GH and cyclic estrogen/progesterone (E/P) replacement on bone mineralization in patients with Turner's syndrome (TS), bone mineral density (BMD) was measured longitudinally. BMDs of the whole body and the lumbar spine in 16 adult female patients with TS (17-38 year old; 0-20 years by length of E/P treatment) were assessed using dual energy X-ray absorptiometry one to 5 times over a treatment period of up to 7 years maximum. GH treatment was performed in 9 cases (GH group), but not in the remaining 7 (non-GH group). E/P replacement therapy was initiated in all patients after they finished GH administration. The BMDs of both the whole body and the lumbar spine in the patients with TS were significantly less than those in age-matched normal subjects, and did not improve with E/P treatment. Although there were no differences in final body height and age at the beginning of E/P administration between the GH and non-GH groups, whole body BMD in the GH group was significantly lower than that in the non-GH group. These results indicate that GH administration in childhood and adolescence and E/P treatment in adulthood did not increase bone mineralization in the TS patients. Therefore, we can conclude that the optimal protocol of hormonal replacement therapy with GH and E/P during childhood and adolescence should be established as soon as possible.

Photosynthesis-dependent removal of 2,4-dichlorophenol by Chlorella fusca var. vacuolata

Of 7 green algae, Chlorella fusca var. vacuolata removed about 23% of 2,4-dichlorophenol (DCP) at 10-80 microM after 4 d when grown photoautotrophically. Removal of DCP was growth-dependent and was suppressed dose-dependently by the photosynthesis inhibitor, 3-(3,4-dichlorophenyl)-1,1-dimethyl urea.

Removal of hazardous phenols by microalgae under photoautotrophic conditions

Various algae were screened for their ability to decrease the concentration of 2,4-dinitrophenol (DNP), as a model compound of hazardous phenols, under photoautotrophic conditions. Chlorella fusca var. vacuolata and Anabaena variabilis grew well and showed high DNP removal ability over the concentration range of 5 to 40 microM. Their abilities to remove various phenols were investigated. More than 90% of 40 microM o- and m-nitrophenol and DNP was removed during the cultivation period of 5 d. o-, p-Chlorophenol and 2,4-dichlorophenol could be removed, but not to a significant extent. C. fusca also removed 85% of bisphenol A, suspected to be an endocrine disrupter. It was found that microalgae would be applicable to the removal of hazardous phenols without the addition of any organic carbon sources.

Epidermoid cyst originating from an intrapancreatic accessory spleen

Pancreatectomy in a 45-year-old woman showed, after pathologic analysis, an epidermoid cyst originating from an intrapancreatic accessory spleen. This mass consisted of parenchymal and cystic components. It is important to note the relation between the splenic parenchyma and the parenchymal component of the mass for the differential diagnosis of a cystic mass in the pancreatic tail.

Intrachannel pulse interactions in dispersion-managed transmission systems: timing shifts

Nonlinear intrachannel interactions responsible for timing shifts in a transmission system with strong periodic dispersion management are investigated. Formulas describing the evolution of the timing shift are obtained for general bit patterns. When average dispersion is negligible, the timing shift is shown to grow linearly in distance in a system with loss and lumped amplification, whereas in a lossless system the timing shift is sufficiently small at every chirp-free point. The analysis agrees with direct numerical simulations.

Quasi-linear optical pulses in strongly dispersion-managed transmission systems

A unified analytical description of the evolution of quasi-linear optical pulses and solitons in strongly dispersion-managed transmission systems is developed. Asymptotic analysis of the nonlocal equation that describes the averaged dynamics of a dispersion-managed system shows that the nonlinearity decreases for large map strength s , as O(log s/s) . The spectral intensity is found to be an invariant of the propagation, which allows the phase shift to be computed. These findings provide a clear description of pulse propagation in the quasi-linear regime, which is characterized by much lower energies than those required for stable dispersion-managed soliton transmission with the same dispersion map.

Resonant nonlinear intrachannel interactions in strongly dispersion-managed transmission systems

Nonlinear intrachannel interactions in a transmission system with strong periodic dispersion management are studied. The ghost pulse at the zero bit is shown to grow resonantly as a result of periodic forcing and temporal phase matching with the signal pulses. The growth rate depends on the degree of overlap between the signals. The analysis agrees with direct numerical simulation of the full system. Growth rates for various bit patterns as a function of map strength are obtained.

The effect of occlusal appliances and clenching on the temporomandibular joint space

It has been suggested that stabilization appliances and mandibular anterior repositioning appliances work by decompressing the temporomandibular joint. To indirectly test this assumption, tomograms of right temporomandibular joints of seven subjects were taken during comfortable closure and maximum clenching in maximum intercuspation and on the two types of occlusal appliances. Outlines of the condyle and the temporal fossa were automatically determined by an edge detection protocol. Upon comfortable closure, the anterior joint space dimension was reduced with stabilization appliances and mandibular anterior repositioning appliances. Upon maximum clenching, the minimum joint space dimension on stabilization appliances was equivalent to that seen in maximum intercuspation, while that on mandibular anterior repositioning appliances was substantially less (P < .05). Findings do not indicate that these appliances induce an increase in joint space during clenching.

Adequacy and long-term prognosis of endoscopic carpal tunnel release

Forty-one hands of 37 patients with idiopathic carpal tunnel syndrome treated by endoscopic carpal tunnel release (ECTR) were followed up for more than one year after surgery. Surgical results were evaluated using Kelly's criteria, the Semmes-Weinstein test, the static and moving 2-point discrimination tests, tip-pinch strength, and motor and sensory nerve conduction studies. Clinical results, according to Kelly's criteria three months after surgery, were excellent or good in 36 hands, and fair or poor in five hands. No recovery was evident at six months and 12 months after surgery in fair and poor hands. Based on these findings, we conclude that a neurolysis of the median nerve and release of constriction of the thenar muscle branch should be performed using the conventional open technique for patients with poor results three months after ECTR if the patients are dissatisfied with ECTR results.

Chirped soliton interaction in strongly dispersion-managed wavelength-division-multiplexing systems

We theoretically analyze nonlinear interactions between chirped solitons in dispersion-managed wavelength-division-multiplexing (WDM) systems. We employ the perturbation method to evaluate frequency and chirp shifts caused by collisions among different WDM channels. It is shown that a chirped soliton suffers less frequency shift and time displacement than an ideal soliton, indicating its potential applicability for WDM systems.

Endoscopic carpal tunnel pressure measurement: a reliable technique for complete release

Carpal tunnel syndrome is diagnosed by clinical symptoms, Tinel's sign, Phalen's test and electromyography. Carpal tunnel pressure measurement can also aid in the precise identification of excessive pressure sites that indicate locations for release. In this study, pressure measurements made during endoscopic carpal tunnel release at 5 points were significantly higher anywhere in the carpal tunnel than outside the tunnel and decreased markedly after release. We concluded that our measurement technique can improve the reliability of endoscopic carpal tunnel release by decreasing the likelihood of missing any nerve entrapment sites.

Guyon's canal syndrome. A different clinical presentation caused by an atypical fibrous band

An atypical case of Guyon's canal syndrome is reported. A 40-year-old woman with hypoaesthesia and claw-finger deformity of the little finger, hypothenar muscle atrophy but no first dorsal interosseous muscle atrophy, underwent release of a fibrous band to decompress the ulnar nerve at the deep branch just proximal to the branch to the abductor digiti minimi muscle. The claw-finger deformity recovered 1 week after surgery.

Synthesis and release of glycosylated prolactin in transfected cells with human prolactin complementary deoxyribonucleic acid

To analyze how the synthesis and release of glycosylated PRL (G-PRL) is regulated, we transfected human PRL complementary deoxyribonucleic acid (cDNA) into three different cell lines consisting of GH3 cells that originated in rat pituitary tissue, Chinese hamster ovary cells, and COS-1 cells generated from monkey renal tissue. 35S-labeled PRLs produced by the cells were immunoprecipitated with anti-human PRL antiserum, and the ratios of G-PRL to total PRL were compared. PRLs of 23 kDa and 25 kDa were detected in the cell lysate and medium. The 25-kDa PRL was confirmed to be a glycosylated form by endoglycosidase treatments. The ratios of G-PRL/total PRL were 0.17-0.33, which were similar in lysates and media and among different cell lines. Pulse-chase experiments revealed that the autonomaous secretion rates of G-PRL and non-glycosylated PRL were almost identical. These results indicate that synthesis and secretion kinetics of human PRL may not be affected by its glycosylation in the cells transfected with PRL cDNA.

Delayed posterior interosseous nerve palsy

A rare case of delayed posterior interosseous nerve palsy that developed 39 years after an unreduced anterior dislocation of the radial head is reported. The posterior interosseous nerve was compressed and narrowed at the arcade of Frohse. Radial head resection and release of the arcade was done. The paralysis continued to recover 6 weeks after operation. The nerve, at the arcade of Frohse, was susceptible to compression by the dislocated radial head, especially in the supinated position. Repeated supination and pronation movement over time may have led to developmental changes that caused the delayed nerve palsy.

[Newly developed detection system for serum Helicobacter pylori antibodies using ELISA and its clinical significance]

Using ELISA, a specific and sensitive system that detects serum immunoglobulin G antibodies against all soluble antigens of Helicobacter pylori (Hp) has been developed. This system is used at three different concentrations of Hp antigens coated on the solid phase of the ELISA. Anti-Hp antibodies were judged positive when the difference in the ELISA values between high and middle or middle and low concentrations of antigen were over the specific values. For the ELISA system, called the three point antigen method, sensitivity and specificity of urease activity were 86.9% and 70.8%, respectively. Positive rate for antibodies to serum Helicobacter pylori in dyspeptic patients was higher than that in healthy subjects.

Polypoid growth and K-ras codon 12 mutation in colorectal cancer

BACKGROUND

To clarify genetic changes in colorectal tumorigenesis, K-ras codon 12 point mutations were examined in 101 ordinary colorectal carcinomas and 6 that complicated ulcerative colitis (UC) with special attention to growth patterns.

METHODS

The depths of invasion of ordinary carcinoma were submucosa (SMCa) in 39 cases, muscularis propria (PMCa) in 33, and far-advanced in 29. Growth patterns of SMCa and PMCa were classified into three types: polypoid-growth type without central depression (Type 1), polypoid-growth type with central depression (Type 2), and nonpolypoid-growth type. DNA samples were extracted from formalin fixed paraffin embedded sections, and K-ras codon 12 mutations were examined by two-step polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

K-ras mutation frequency was higher in Type 1 SMCa than in nonpolypoid SMCa, 56% (9/16) versus 6% (1/17), respectively, and in PMCa, 78% (7/9) versus 23% (3/13), respectively. In 6 UC carcinomas, a K-ras mutation was detected in only one polypoid carcinoma and none were detected in five nonpolypoid carcinomas.

CONCLUSIONS

These results and the authors' previous study suggest that nonpolypoid carcinomas may be derived from flat adenomas, whose K-ras mutation incidence also was low, and this pathway is different from a genetic model based on the ordinary adenoma-carcinoma sequence through polypoid adenomas.

Polypoid growth and K-ras codon 12 mutation in colorectal cancer

BACKGROUND

To clarify genetic changes in colorectal tumorigenesis, K-ras codon 12 point mutations were examined in 101 ordinary colorectal carcinomas and 6 that complicated ulcerative colitis (UC) with special attention to growth patterns.

METHODS

The depths of invasion of ordinary carcinoma were submucosa (SMCa) in 39 cases, muscularis propria (PMCa) in 33, and far-advanced in 29. Growth patterns of SMCa and PMCa were classified into three types: polypoid-growth type without central depression (Type 1), polypoid-growth type with central depression (Type 2), and nonpolypoid-growth type. DNA samples were extracted from formalin fixed paraffin embedded sections, and K-ras codon 12 mutations were examined by two-step polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

K-ras mutation frequency was higher in Type 1 SMCa than in nonpolypoid SMCa, 56% (9/16) versus 6% (1/17), respectively, and in PMCa, 78% (7/9) versus 23% (3/13), respectively. In 6 UC carcinomas, a K-ras mutation was detected in only one polypoid carcinoma and none were detected in five nonpolypoid carcinomas.

CONCLUSIONS

These results and the authors' previous study suggest that nonpolypoid carcinomas may be derived from flat adenomas, whose K-ras mutation incidence also was low, and this pathway is different from a genetic model based on the ordinary adenoma-carcinoma sequence through polypoid adenomas.

Polypoid growth and K-ras codon 12 mutation in colorectal cancer

BACKGROUND

To clarify genetic changes in colorectal tumorigenesis, K-ras codon 12 point mutations were examined in 101 ordinary colorectal carcinomas and 6 that complicated ulcerative colitis (UC) with special attention to growth patterns.

METHODS

The depths of invasion of ordinary carcinoma were submucosa (SMCa) in 39 cases, muscularis propria (PMCa) in 33, and far-advanced in 29. Growth patterns of SMCa and PMCa were classified into three types: polypoid-growth type without central depression (Type 1), polypoid-growth type with central depression (Type 2), and nonpolypoid-growth type. DNA samples were extracted from formalin fixed paraffin embedded sections, and K-ras codon 12 mutations were examined by two-step polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

K-ras mutation frequency was higher in Type 1 SMCa than in nonpolypoid SMCa, 56% (9/16) versus 6% (1/17), respectively, and in PMCa, 78% (7/9) versus 23% (3/13), respectively. In 6 UC carcinomas, a K-ras mutation was detected in only one polypoid carcinoma and none were detected in five nonpolypoid carcinomas.

CONCLUSIONS

These results and the authors' previous study suggest that nonpolypoid carcinomas may be derived from flat adenomas, whose K-ras mutation incidence also was low, and this pathway is different from a genetic model based on the ordinary adenoma-carcinoma sequence through polypoid adenomas.

Lower incidence of K-ras codon 12 mutation in flat colorectal adenomas than in polypoid adenomas

In order to clarify genetic changes in flat adenomas, K-ras codon 12 point mutations were examined in 56 flat adenomas, 81 polypoid adenomas and 42 cancers of colon and rectum. The mutation frequency in flat adenomas was 23% (13/56), significantly lower than that in polypoid adenomas (67%: 54/81) and cancers (76%: 32/42). Even mildly dysplastic adenomas or small (less than 5 mm) adenomas showed higher mutation incidence in polypoid type (62%, 57%) than in flat type (23%, 19%). Among flat adenomas, flat elevated lesions exhibited relatively higher mutation frequency than completely flat or depressed ones. As for cancers, 14 tumors (33%) contained mutations only in a minor tumor cell population, indicating that these mutations occur at a late stage of tumorigenesis. These results suggest that the adenoma-carcinoma sequence through flat adenomas may be different from that through polypoid adenomas, and genetic changes may be heterogeneous in colorectal carcinogenesis.

Inhibition of 7,12-dimethylbenz[a]anthracene-induced lipid peroxidation and mammary tumor development in rats by vitamin E in conjunction with selenium

The effects of combined dietary vitamin E supplementation and a relatively low increase in selenium levels on 7,12-dimethylbenz[a]anthracene (DMBA) induction of lipid peroxidation in the short term and development of mammary tumors in the long term were investigated in female Sprague-Dawley rats. Control animals were fed the basal diet (20 mg/kg vitamin E and 0.6 mg/kg selenium) throughout the experiment. Three other groups received a high vitamin E diet (235 mg/kg vitamin E and 0.6 mg/kg selenium) at different times, the first two from three weeks after DMBA treatment and the other throughout the experiment. When the vitamin E diet with selenium supplementation was applied until three weeks after DMBA or until the termination of the experiment, tumor yields (tumors per rat) were significantly inhibited compared with the control group. On the other hand, delaying the supplementation of vitamin E until three weeks postcarcinogen produced no prophylactic effect. The elevation of lipid peroxidation levels observed immediately after DMBA administration was also significantly inhibited in both mammary fat pads and livers of animals in the high vitamin E group. It was therefore concluded that the inhibitory effect of vitamin E in combination with selenium on tumorigenesis might be causally related to reduction of carcinogen treatment associated with lipid peroxidation, the latter presumably playing an important role in DMBA-induced mammary carcinogenesis.

Microassay for GM1 ganglioside beta-galactosidase activity using high-performance liquid chromatography

A simple and sensitive assay for GM1 ganglioside (GM1) beta-galactosidase activity was devised by direct measurement of released D-galactose using high-performance liquid chromatography (HPLC). GM1 beta-galactosidase activity in crude samples such as brain homogenates could be measured by this method. After incubation of brain homogenate for 1 h with GM1 at 37 degrees C and pH 4.4 in the presence of sodium taurodeoxycholate, the reaction was terminated by heating at 100 degrees C for 2 min and the supernatant from the centrifuged sample was analysed directly by HPLC. D-Galactose isolated by HPLC was converted into a fluorescent compound by a post-column reaction with arginine at 150 degrees C and the fluorescence intensity at 430 nm was measured with excitation at 320 nm. By this method 10 pmol of D-galactose could be measured and the fluorescence intensity was linear up to 1 mmol of D-galactose. Using this method, the optimal conditions for the activity of this enzyme were re-examined. As an application, the enzyme activity in the brain of a patient with GM1 gangliosidosis was examined. This method can be applied to any natural substrates, glycolipids or glycoproteins, the terminal galactose of which is hydrolysed by this enzyme.

Molecular characterization of the virC genes of the Ti plasmid

The virC (formerly bak) complementation group of the nopaline-type Ti plasmid pTiC58 encodes two proteins, VirC1 and VirC2. According to the primary structure of the polypeptides predicted by the nucleotide sequence, VirC1 is composed of 231 amino acids with a total molecular mass of 25.5 kilodaltons, and VirC2 is composed of 202 amino acids with a molecular mass of 22.1 kilodaltons. The pTiC58 VirC1 and VirC2 polypeptides are equal in length to VirC1 and VirC2 of the octopine-type plasmid pTiA6NC. VirC1 proteins of pTiC58 and pTiA6NC are identical at 202 (87.4%) of the amino acid residues, and this homology is distributed fairly evenly throughout the protein. VirC2 identities occur at 142 residues (70.3%), but fall predominantly into two blocks of higher homology (84.6 and 78.5%) separated by a 41-residue segment of much lower homology (29.3%). Mutations in virC resulted in attenuated virulence on all hosts tested, the severity of attenuation varying markedly depending on the type of plant inoculated. For example, the attenuation was more pronounced on Kalanchoe than on sunflower or jimson weed. Virulence was restored to normal on all hosts by in-trans complementation with corresponding nonmutant DNA fragments of pTiC58 or of the octopine-type plasmid pTi15955. Two oligopeptides from within the predicted pTiC58 VirC1 polypeptide were synthesized and used to raise antibodies. These antibodies were used to detect the VirC1 product of both pTiC58 and pTi15955. In both cases, virC was expressed constitutively in the Agrobacterium tumefaciens ros mutant. The homology between virC genes of octopine- and nopaline-type Ti plasmids thus includes a conservation of genetic regulatory control mechanisms as well as considerable conservation of the primary structure of the protein products.

Characterization of the virE locus of Agrobacterium tumefaciens plasmid pTiC58

The virE locus that is responsible for the efficiency of infection by Agrobacterium tumefaciens (T. Hirooka and C. Kado, J. Bacteriol. 168:237-243, 1986) is located next to the right boundary of the virulence (Vir) region of the nopaline plasmid pTiC58. This locus is very similar to the virE locus of octopine type Ti plasmids on the basis of nucleotide and amino acid sequence comparisons as well as genetic complementation analyses. The nucleotide sequence of virE revealed three open reading frames, arranged as an operon, with a potential coding capacity for proteins of 9, 7.1, and 63.5 kilodaltons. The promoter region of virE was analyzed by using gene fusions to promoterless cat and lux genes. Two different promoters were detected, one which operates in A. tumefaciens and one which operates in Escherichia coli. virE is transcribed from left to right toward the T region. In A. tumefaciens, the expression of virE was induced by acetosyringone and required the presence of pTiC58.

Location of the right boundary of the virulence region on Agrobacterium tumefaciens plasmid pTiC58 and a host-specifying gene next to the boundary

The right boundary of the virulence (Vir) region of the nopaline plasmid pTiC58 of Agrobacterium tumefaciens was determined by transposon insertion, cartridge emplacement, and deletion mutagenesis. Genetic complementation with mutant and wild-type alleles led to the identification of the virE locus at the right boundary, which was located about 6 kilobases from the left border of the segment of DNA that is transferred into the plant genome. virE is 2.0 kilobases long and encodes at least one protein of 69 kilodaltons. Various mutations in virE resulted in different truncated lengths of the 69-kilodalton protein. As this protein was increasingly truncated from the carboxy terminus, the host range of A. tumefaciens and the frequency of tumor formation diminished concomitantly. Thus, as one of its functions, the 69-kilodalton protein of virE is probably involved in some aspect of the host range specificity of A. tumefaciens and in infection efficiency.

Endoscopic bipolar electrocoagulation in upper gastrointestinal bleeding

A new endoscopically deliverable bipolar electrocoagulator has been developed, and employed clinically to treat upper gastrointestinal bleeding in 53 patients on 61 occasions. By direct application of the electrode to the bleeding vessels immediate hemostasis was achieved in 52 out of 53 bleeding vessels. Non-bleeding visible vessels were safely coagulated. Arrest of bleeding was permanent in 44 patients (83%), of whom 20 were candidates for emergency operation because of massive, continued or recurrent bleeding. Rebleeding after hemostasis by bipolar electrocoagulation was noted in 8 patients (15%); however, the majority of rebleeds were those with acute mucosal lesions who had serious underlying medical problems. Emergency operation was performed in 5 patients, and was averted in most patients after successful hemostasis by bipolar electrocoagulation. There were no complications related to the procedure. Bipolar electrocoagulation with our coagulator is a safe and easily applicable technique that is a promising addition to currently available endoscopic hemostatic methods.

Effect of beta-glucuronidase inhibitor on azoxymethane-induced colonic carcinogenesis in rats

In this study of the role of microfloral beta-glucuronidase in colonic carcinogenesis, the effect of beta-glucuronidase inhibitor was evaluated. Starting at 5 weeks of age, male Donryu rats were fed either a semisynthetic diet or the same diet containing 0.1% beta-glucuronidase inhibitor as N-cyclohexyl-5-O-acetyl-2,4-O-p-methoxybenzylidene) -D-glucaro-1-amide-6,3-lactone (C-GAL). All animals were given s.c. injections of 7.4 mg azoxymethane (AOM) per kg body weight once a week for 11 weeks and followed for an additional 20 weeks. Most animals receiving the colonic carcinogen developed tumors in the colon, and a few also developed tumors in the small intestine. However, the number of tumors in the large intestine of the rats given C-GAL at the same time as AOM was significantly lower than in the control rats, especially in the proximal half of the colon, but those given C-GAL after AOM treatment had almost the same number of colon tumors as did the controls. It is concluded that, since bacterial beta-glucuronidase activity in the feces of rats given 0.1% C-GAL was significantly inhibited, intestinal microfloral beta-glucuronidase may play an important role in colonic carcinogenesis caused by AOM.