Detection of DCC and Ki-ras gene alterations in colorectal carcinoma tissue as prognostic markers for liver metastatic recurrence

BACKGROUND

The mortality of patients with colorectal carcinoma depends mainly upon subsequent liver metastasis even after curative operation. However, it is very difficult to predict the incidence of liver metastasis by analyzing conventional tumor markers or pathologic findings. In the current study, the authors examined the genetic alterations of p53/DCC loci and Ki-ras in colorectal carcinoma in relation to liver metastasis, and investigated whether these gene alterations could be prognostic markers for liver metastasis.

METHODS

Primary tumor tissue samples were collected at surgery from 30 patients with no liver metastasis and 24 patients with liver metastasis. Among the 30 patients with no liver metastasis at surgery, 9 developed liver metastasis after surgery. After the extraction of DNA, we investigated the loss of heterozygosity at p53/DCC loci and mutations of Ki-ras codon 12 in the colorectal carcinoma tissue from these patients.

RESULTS

The incidence of allelic loss of the DCC locus was significantly greater for patients with liver metastasis that for patients who had no liver metastasis for more than 2 years (19/20:95% vs 2/5:40%, P < 0.05). However, mutations of Ki-ras codon 12 were significantly less in patients with liver metastasis than in patients with no liver metastasis for more than 2 years (6/33:18% vs 6/11:55%, P < 0.05).

CONCLUSION

The current study indicated that detection of allelic loss of DCC and absence of Ki-ras codon 12 mutations are associated with the metastatic potential of colorectal carcinoma in the liver. These results suggested that these gene alterations might be reliable biologic markers for assessing the potential of liver metastasis after colorectal resection.

GLP-1 depolarizes the rat pancreatic beta cell in a Na(+)-dependent manner

An intestinal hormone glucagon-like-peptide-1 (GLP-1) is a prominent candidate for incretin. In vitro experiment showed (Fridolf and Ahren, Mol. Cell. Endocrinol., 96 (1993) 85-90) that GLP-1 increased both insulin secretion and the efflux of 45Ca2+ in a Na(+)-dependent manner. Further, GLP-1 depolarizes the pancreatic beta cells in the presence of high concentration of glucose. Here, we report the effect of GLP-1 on the membrane potential with a physiological concentration of glucose in perforated patch clamp of primary cultured rat beta cells. 10 nM GLP-1 depolarized the beta cell, which was completely reversed by replacing Na+ with the impermeant molecule N-methyl-D-glucamine (NMDG). The Ca2+ channel blocker, Co2+ suppressed the Ca2+ spikes without hyperpolarizing the cell. GLP-1-induced insulin secretion in perifused islets was also suppressed by a prior replacement of Na+ with NMDG. In addition, GLP-1 slightly augmented the long-lasting Ba2+ current, which was reverted to the control level by a selective inhibitor of protein kinase A, H-89. These results indicate: (i) GLP-1 depolarizes the beta cell by activating the membrane Na+ permeability; (ii) GLP-1 slightly modulates the L-type Ca2+ channel probably through protein kinase A; and (iii) at least in part, these mechanisms may be involved in the insulin secretion induced by GLP-1.

Increased preproenkephalin mRNA and preprotachykinin mRNA in the striatum of Rolling mouse Nagoya

Although Rolling mouse Nagoya (RMN) has been considered to demonstrate cerebellar dysfunction, our previous metabolic and electrophysiological studies also revealed a dysfunction of the basal ganglia, with the presumable primary site of dysfunction being the striatum. In the present study, we investigated the neurochemical functions of the striatum. In RMN, both preproenkephalin mRNA and preprotachykinin mRNA increased significantly in the striatum, with unaltered GAD mRNA, [(3)H]spiperone binding, [(3)H]QNB binding and preprosomatostatin mRNA, thus indicating the dysfunction of striatal projection neurons. These findings support the hypothesis that the site of primary dysfunction in the basal ganglia is in the striatum of RMN.

Ammonia response to exercise in patients with congestive heart failure

OBJECTIVE

To assess energy depletion in skeletal muscle in patients with congestive heart failure by measuring blood purine metabolites during exercise and, at the same time, determine the implications of the ammonia response to exercise in these patients.

SETTING

Tottori University Hospital, Yonago, Japan.

PATIENTS

49 heart failure patients (New York Heart Association (NYHA) grades I-III) and 16 normal subjects.

MAIN OUTCOME MEASURES

Blood lactate, ammonia, and hypoxanthine levels were measured during exercise with expired gas analysis.

RESULTS

In normal exercising subjects as well as in each heart failure subgroup, the ammonia threshold was significantly higher than both the lactate threshold [control: 21.8 (SD 5.3) v 17.4 (3.3) ml/kg/min; NYHA class I: 18.9 (3.8) v 15.5 (2.6); class II: 14.8 (2.5) v 12.7 (2.4); class III: 13.5 (2.6) v 11.8 (2.5)] and the ventilatory threshold (P < 0.01). The difference between the ammonia and lactate thresholds was noted in all normal subjects and in all heart failure patients. The ammonia threshold, however, was significantly lower in heart failure patients than in normal subjects and it decreased with increasing NYHA class (P < 0.01). Maximum ammonia levels were lower in the heart failure group and decreased further with higher NYHA classifications [control: 198 (52) mg/dl; NYHA class I: 170 (74); class II: 134 (58); class III: 72 (15); P < 0.01]. There were significant correlations between maximum ammonia values and maximum lactate, oxygen consumption, and hypoxanthine levels (r = 0.74, 0.48, and 0.87, respectively; P < 0.001).

CONCLUSIONS

The ammonia threshold may reflect the onset of ATP depletion in exercising skeletal muscles, as opposed to the onset of anaerobic respiration. It seems therefore that energy depletion in skeletal muscles during exercise occurs after attaining the anaerobic threshold. Both aerobic and anaerobic capacities of skeletal muscle are reduced in patients with congestive heart failure.

[Diagnosis and targeting therapy of colorectal cancer using antibody]

Application of monoclonal antibody for diagnosis and therapy of colorectal cancer was reviewed. The history and present status of radioimmunoimaging of cancer were presented. Immuno-guided surgery using radiolabeled antibody and hand-aided detector during surgery is a promising approach for complete excision of cancerous region. Also, a new antibody labeling method using a micro-magnet instead of radioisotopes may lead to a new era in immunodiagnosis of cancer. Finally, immunotargeting chemotherapy using antibody-anticancer drug conjugates was reviewed. A new type of immunoconjugate composed of human/mouse chimeric antibody and Neocarzinostatin seems to be one of the most promising drug formulas for immunotargeting chemotherapy.

[Initial experience with partial left ventriculectomy as a treatment for end-stage heart failure]

PURPOSE

To evaluate the efficacy of left ventriculectomy, on a short term basis, as a treatment for patients with end-stage heart failure.

METHODS

From February to June 1995, 7 patients with end-stage heart failure underwent partial left ventriculectomy. Before the surgical procedure, 7 (100%) patients were in functional class IV. Three (42%) patients needed inotropic support for hemodynamic stability. The mean daily dose of furosemide was l48.67 +/- 128.27 mg, of captopril 87.50 +/- 95.20 mg and of digoxin 0.23 +/- 0.04. Mean left ventricular diastolic dimension determined by 2-D echocardiography was 78.29 +/- 12.63 mm, mean left ventricular ejection fraction, determined by radionuclide ventriculography, was 0.15 +/- 0.05 whereas mean transpulmonary gradient and pulmonary vascular resistance in Wood units, determined by right heart catheterization, were 16.80 +/- 8.80 and 6.57 +/- 3.22, respectively.

RESULTS

Sixty days after the surgery, the mean functional class was 1.71 +/- 0.48 (p = 0.009), the mean left ventricular diastolic dimension 64.67 +/- 11.41 mm (p = 0.02) and the mean left ventricular ejection fraction 0.22 +/- 0.04 (p = 0.02).

CONCLUSION

The left ventriculectomy is a promising treatment for patients with end-stage heart failure.

A new and potent calmodulin antagonist, HF-2035, which inhibits vascular relaxation induced by nitric oxide synthase

HF-2035, 2-[N-(2-aminoethyl)-N-(2,4,5-trichlorobenzenesulfonyl)] amino-N-(4-chlorocinnamyl)-N-methylbenzylamine, was synthesized and its effects on calmodulin-dependent enzymes were investigated. HF-2035 inhibited calmodulin kinase I, calmodulin kinase II and myosin light-chain kinase with IC50 values of 1.3 microM, 1.6 microM and 68 microM, respectively. HF-2035 also inhibited the activity of recombinant rat neuronal nitric oxide synthase, one of the calmodulin-dependent enzymes, with a Ki of 0.78 microM. Partially purified nitric oxide synthase of rat brain was also inhibited by HF-2035 with an IC50 of 3.2 microM. Kinetic analysis indicated that this inhibitory effect of HF-2035 was competitive with respect to calmodulin. We examined the effects of HF-2035 on constitutive nitric oxide synthase in a bioassay using vascular strips of rabbit carotid artery with and without endothelium. HF-2035 inhibited acetylcholine- and calcium ionophore, A23187 (6S-[6 alpha (2S*,3S*),8 beta (R*),9 beta, 11 alpha]-5- (methylamino)-2-[[3,9,11-trimethyl-8-[1-methyl-2-oxo-2-(1H-pyrrol-2-yl)- ethyl]-1,7-dioxaspiro[5.5]undec-2-yl]methyl]-4-benzoxazol ecarboxylic acid)-induced relaxation of endothelium-intact strips with an ED50 of 1.5 +/- 0.5 microM and 2.8 +/- 1 microM, respectively. This compound, however, did not inhibit N-nitroso-N-morpholinoaminoacetonitrile (SIN-1A), an exogenous nitric oxide donor, -induced relaxation of endothelium-denuded strips. W-7 (N-(6-aminohexyl)-5-chloro-1- naphthalenesulfonamide) inhibited acetylcholine-induced relaxation with an ED50 of 46 +/- 7 microM, which was 30-fold less potent than HF-2035. HF-2035 was unable to inhibit the activity of the inducible form of nitric oxide synthase in isolated thoracic aorta of rat treated with Escherichia coli lipopolysaccharide. These findings suggest that HF-2035 is a new and potent calmodulin antagonist, and may be used as a mother compound to develop more selective inhibitors of constitutive nitric oxide synthase.

Contribution of sustained Ca2+ elevation for nitric oxide production in endothelial cells and subsequent modulation of Ca2+ transient in vascular smooth muscle cells in coculture

To elucidate the intracellular Ca2+ (Ca2+i ) transient responsible for nitric oxide (NO) production in endothelial cells (ECs) and the subsequent Ca2+i reduction in vascular smooth muscle cells (VSMCs), we administrated four agonists with different Ca2+i-mobilizing mechanisms for both cells in iso- or coculture. We monitored the Ca2+i of both cells by two-dimensional fura-2 imaging, simultaneously measuring NO production as NO2-. The order of potency of the agonists in terms of the peak Ca2+i in ECs was bradykinin (100 nM) > ATP (10 microM) > ionomycin (50 nM) > thapsigargin (1 microM). In contrast, the order in reference to both the extent of Ca2+i reduction in cocultured VSMCs and the elevation in NO production over the level of basal release in ECs completely matched and was ranked as thapsigargin > ionomycin > ATP > bradykinin. Treatment by NG-monomethyl-L-arginine monoacetate but not indomethacin or glybenclamide restored the Ca2+i response in cocultured VSMCs to the isoculture level. In ECs, when the Ca2+ influx was blocked by Ni2+ or by chelating extracellular Ca2+, all four agonists markedly decreased NO production, the half decay time of the Ca2+i degenerating phase, and the area under the Ca2+i curve. The amount of produced NO hyperbolically correlated to the half decay time and the area under the Ca2+i curve but not to the Ca2+i peak level. Thus, the sustained elevation of Ca2+i in ECs, mainly a result of Ca2+ influx, determines the active NO production and subsequent Ca2+i reduction in adjacent VSMCs. Furthermore, L-arginine but not D-arginine or L-lysine at high dose (5 mM) without agonist enhanced the NO production, weakly reduced the Ca2+i in ECs, and markedly decreased the Ca2+i in VSMCs, demonstrating the autocrine and paracrine effects of NO (Shin, W. S., Sasaki, T., Kato, M., Hara, K., Seko, A., Yang, W. D., Shimamoto, N., Sugimoto, T., and Toyo-oka, T. (1992) J. Biol. Chem. 267, 20377-20382).

Differences in the reduced 18F-Dopa uptakes of the caudate and the putamen in Parkinson's disease: correlations with the three main symptoms

It has been reported that the F-Dopa (FD) uptake in patients with idiopathic Parkinson's disease (PD) decreased significantly in the caudate and putamen when compared to controls. The FD uptake severely decreased in the putamen, while it was relatively spared in the caudate nucleus. We also previously reported that atypical parkinsonism with no or little tremor showed a homogeneously reduced FD uptake in both the caudate and the putamen. In this study we evaluated the caudate and the putaminal FD uptakes in relation to the three main symptoms in PD. The FD uptake was measured by PET with 6-L-[18F]fluorodopa in 17 patients with PD. The caudate and the putaminal FD uptake ratios to the cerebellum at 120 min were evaluated. The caudate and the putaminal FD uptake ratios in the patients with PD decreased as their clinical stages advanced. These decreases also correlated with the degree of rigidity and bradykinesia. However, such decreases did not correlate with the degree of tremor. The caudate-putamen index (CPI)(%), which was calculated by a formula based on the difference in the uptakes of the caudate and putamen divided by the caudate uptake, indicated 11.6 +/- 3.6, 16.5 +/- 5.5 and 18.3 +/- 4.1 in the group of no, mild and moderate tremor, respectively, and increased as the degree of tremor advanced. The CPI in the group of moderate tremor significantly increased from that in the group of no tremor (P < 0.04). However, the CPI did not correlate with the clinical stage, the degree of rigidity or the degree of bradykinesia. The FD/PET study therefore effectively demonstrated the severity of the clinical symptoms of rigidity and bradykinesia in patients with PD in correlation with a decrease in the FD uptakes in the caudate and the putamen, and it also demonstrated that the severity of tremor might have a different mechanism from that of such other symptoms as rigidity and bradykinesia.

Effects of bradykinin on the intracellular calcium concentration of pancreatic acinar AR42J cells

We examined the effects of bradykinin (BK) on the intracellular free calcium concentration ([Ca2+]i) in rat pancreatic acinar AR42J cells. BK induced a dose-dependent rise in [Ca+2]i in AR42J cells between the concentrations of 10(-12)M and 10(-7)M. The BK-evoked response was not affected by the presence of Co2+ or the absence of extracellular calcium. This response was suppressed by neomycin or the B2 antagonist, but not by the B1 antagonist. The response was also attenuated by treatment with dexamethasone. These results suggest that BK increases [Ca2+]i through the B2 receptors by promoting the phosphatidyl inositol turn-over and that, in the process of azaserine-induced undifferentiation, the pancreatic acinar cells strongly express the BK receptors.

Engraftment of human tumor-infiltrating lymphocytes and the production of anti-tumor antibodies in SCID mice

We report here the placement of nondisrupted 1-mm3 pieces of fresh human lung tumor biopsy tissue into the subcutis of severe combined immunodeficient (SCID) mice results in the engraftment of tumor-infiltrating leukocytes (TIL) in all but 5 of 148 mice inoculated with 39 different biopsy tissue specimens. In mice coengrafted with tumor and TIL the normal histologic architecture of the tumor and TIL interface was maintained for up to 22 wk. The TIL in the xenograft were shown to divide and were maintained exclusively at the site of tumor inoculation. It is established here that plasma cells in the TIL population produce Abs that react in western blots with tumor cell lysates. These Abs were shown to react with high and low m.w. proteins derived from both the membrane and cytosolic fractions of tumor cell lysates. The production of human Ig was found to be T cell dependent, and immunohistochemistry and in situ hybridization of DNA, using a human-specific cDNA probe, established the human identity of the tumor and TIL. High levels of human Ig in the sera of mice inoculated with tumor biopsy tissue are associated with the growth arrest of adenocarcinoma xenografts. Our results establish the co-engraftment of human tumors and TIL into SCID mice as new animal model with which to evaluate TIL function and novel therapeutic strategies that are designed to augment TIL anti-tumor activity.

Engraftment of human tumor-infiltrating lymphocytes and the production of anti-tumor antibodies in SCID mice

We report here the placement of nondisrupted 1-mm3 pieces of fresh human lung tumor biopsy tissue into the subcutis of severe combined immunodeficient (SCID) mice results in the engraftment of tumor-infiltrating leukocytes (TIL) in all but 5 of 148 mice inoculated with 39 different biopsy tissue specimens. In mice coengrafted with tumor and TIL the normal histologic architecture of the tumor and TIL interface was maintained for up to 22 wk. The TIL in the xenograft were shown to divide and were maintained exclusively at the site of tumor inoculation. It is established here that plasma cells in the TIL population produce Abs that react in western blots with tumor cell lysates. These Abs were shown to react with high and low m.w. proteins derived from both the membrane and cytosolic fractions of tumor cell lysates. The production of human Ig was found to be T cell dependent, and immunohistochemistry and in situ hybridization of DNA, using a human-specific cDNA probe, established the human identity of the tumor and TIL. High levels of human Ig in the sera of mice inoculated with tumor biopsy tissue are associated with the growth arrest of adenocarcinoma xenografts. Our results establish the co-engraftment of human tumors and TIL into SCID mice as new animal model with which to evaluate TIL function and novel therapeutic strategies that are designed to augment TIL anti-tumor activity.

Expression of TGF-beta type I and type II receptors in rat eyes

Transforming growth factor beta (TGF-beta) transduces signals through mediation of type I and type II serine/threonine kinase receptors. The expression of TGF-beta type I (T beta R-I) and II (T beta R-II) receptors in rat eyes was investigated immunohistochemically. T beta R-I and T beta R-II immunoreactivity was detected in corneal and conjunctival epithelial cells, corneal endothelial cells, ciliary epithelial cells, lens epithelial cells, retinal pigment epithelial cells, and choroidal vessels. This co-expression of T beta R-I and T beta R-II indicates that the above cells respond to TGF-beta and, because TGF-beta is reported to be produced in ocular tissues, that it may have important autocrine and/or paracrine roles in the growth and metabolism of ocular tissues in situ.

Bone morphogenetic protein type IB receptor is progressively expressed in malignant glioma tumours

The distribution of bone morphogenetic protein (BMP) type I receptors and the activin type I receptor (ActR-I) was investigated in 16 cases of human glioma and five cases of non-tumourous gliosis tissue by immunohistochemical technique. Both BMP type IA (BMPR-IA) and the type IB (BMPR-IB) receptors were detected in human glioma cells. A significant increase in BMPR-IB in tumour cells was observed in malignant glioma compared with both low-grade astrocytomas (n=16, P<0.005) and gliosis (n=13, P<0.001). However, enhancement of BMPR-IA staining was moderate and ActR-I staining was only weakly expressed in the malignant glioma tumours. Osteogenic protein (OP)-1/BMP-7, which is known to bind BMPR-IA, BMPR-IB and ActR-I, was expressed in nervous tissue and was also detected in anaplastic areas of malignant glioma. In contrast to the tissue materials, BMPR-IA was expressed to a stronger degree than BMPR-IB in human glioma cell lines; the growth of these cells was suppressed by OP-1. These results suggest the presence of BMP receptors and a functional role for BMPs in malignant glioma.

Atrophic changes of gastric mucosa are caused by Helicobacter pylori infection rather than aging: studies in asymptomatic Japanese adults

BACKGROUND

The current study was designed to evaluate the effect of aging and Helicobacter pylori infection on the gastric mucosa in asymptomatic Japanese adults.

MATERIALS AND METHODS

Eighty-five asymptomatic healthy adults were recruited from a health-screening center in Sapporo. All subjects underwent endoscopy and gastric biopsy, and serum was obtained for IgG antibodies to H. pylori, serum gastrin, and pepsinogen levels.

RESULTS

The prevalence of atrophic change of the gastric mucosa assessed by pathological findings increased with age (49% in the 30- to 39-year-old group compared to 89% in those 60 years and older, p < .001). The frequency of intestinal metaplasia also increased with age (38% in the 30- to 39-year-old group compared to 82% in those 60 years and older, p < .001). In contrast, the frequency of atrophic gastritis and intestinal metaplasia was extremely low in the H. pylori seronegative group regardless of age. Mean serum gastrin level in H. pylori-positive adults was significantly greater than in those who were H. pylori-negative (114.3 +/- 11.2 compared to 65.8 +/- 6.5 pg/ml, p < .03). The serum pepsinogen I-II ratio was significantly lower in those with H. pylori infection than in those without (3.1 compared to 6.6, p < .0001).

CONCLUSIONS

These results suggest that the chronological changes in the gastric mucosa in Japanese individuals are either entirely related to H. pylori infection or the process is greatly accelerated by H. pylori infection.

Postprandial responses of liver blood flow prior to and following hepatectomy in conscious dogs

The responses of the portal and hepatic arterial blood flows to various diets and nutrients were measured simultaneously in conscious dogs prior to and following hepatic resection. Prior to hepatectomy, the increase in the portal blood flow was significantly larger in response to an elemental diet, fats, or amino acids than to glucose or water. The peak increase was 60.2 +/- 14.4 ml for water, 144.7 +/- 22.1 ml for a 150-cal elemental diet, 168.5 +/- 16.1 ml for a 300-cal elemental diet, 86.7 +/- 14.0 ml for a glucose solution, 159.3 +/- 16.7 ml for an amino acid meal, and 188.5 +/- 25.3 ml for a fat meal. Following partial hepatectomy, fats and amino acids induced an increase in the portal blood flow similar to that prior to hepatectomy. Glucose and the elemental diet, on the other hand, induced a significantly larger increase in portal blood flow following the surgery although water did not. The peak increase was 144.4 +/- 27.8 ml for glucose (166% of the peak increase prior to hepatectomy) and 221.8 +/- 32.5 ml for the 300-cal elemental diet (132%). The postprandial response of the hepatic artery to every diet was quite different among the dogs and there were no significant changes both prior to and following surgery. The different response of the portal flow to intraluminal glucose following partial hepatectomy may be due to alterations in glucose metabolism following hepatectomy. We have shown that the postprandial response of the portal blood flow varies with the type of nutrient, and it can be altered by hepatectomy.

[Pulmonary lymphangiomyomatosis with tuberous sclerosis and endolymphatic stromal myosis of the uterus]

Pulmonary lymphangiomyomatosis is a rare disorder that affects only women of reproductive age. The lung shows numerous cystic changes and striking proliferation of smooth muscle around the airways, blood vessels, and lymphatic channels. We encountered a patient with pulmonary lymphangiomyomatosis who had repeated pneumothorax and bloody sputum over 10 years. The patient also had other lesions, including intracranial calcification, renal angiomyolipoma and endolymphatic stromal myosis of the uterus. The first two findings are known as tuberous sclerosis, and lymphangiomyomatosis is considered to be a form fruste of tuberous sclerosis. However, we know of no previous reports of uterine lesions in this disease. Lymphangiomyomatosis may be a systemic disorder of smooth muscle.

Cloning of cDNA encoding for a novel isozyme of fructose 6-phosphate, 2-kinase/fructose 2,6-bisphosphatase from human placenta

Two independent cDNA clones encoding fructose 6-phosphate, 2-kinase/fructose 2,6-bisphosphatase were isolated from a human placental cDNA library. The deduced amino acid sequences showed that one of the clones, 2K-1, was almost identical to the rat testis isozyme and the other, 2K-3, was different from any known isozymes expressed in mammalian tissues. The results of Southern blot analysis suggested that clones 2K-1 and 2K-3 were encoded as single copy genes and located in different parts of the genome. Since open reading frames of the cDNA clones were not complete, we obtained the 5'-end of the clone 2K-3 cDNA using the 5'-rapid amplification of cDNA end method. The entire cDNA (HP; 1,756 bp) had a coding capacity of 519 amino acids (M(r) = 59,410), and putative phosphorylation sites for protein kinases A and C on the C terminus. Northern blot analysis using a fragment of the HP as a probe showed that a major band of 5.4 kb, significantly different in size from known isozyme mRNAs such as liver (2.1 kb), muscle (1.9 kb), heart (4.0 kb), and testis (2.0 kb), was present in poly(A)+RNA preparations of human first trimester and term placentae. These results strongly suggested that this 5.4 kb mRNA codes a novel isozyme of fructose 6-phosphate,2-kinase/fructose 2,6-bisphosphatase.

A classical strain of Vibrio cholerae with diminished ability to process the proteolytically sensitive site in the A subunit of cholera toxin

Vibrio cholerae O1, No. 31, a strain isolated from a patient with mild diarrhea, produced mainly the unnicked cholera toxin. The amount of toxin that had accumulated in the cells was approximately 200 times lower than that secreted into the culture medium. When the unnicked toxin was purified by three successive column chromatographies and then extracted from the polyacrylamide gel, the unnicked toxin showed two bands corresponding to the A and B subunits by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the A1 fragment was detected by trypsinization. Biological and enzymatic activities of the purified toxin with trypsinization were identical to those of cholera toxin from V. cholerae 569B as seen in the rabbit skin permeability test and the NAD:agmatine ADP-ribosyltransferase assay. DNA sequences of the A and B subunits were identical to those of the A- and B-subunit genes from the El Tor 2125 and classical 0395 strains, respectively. These data suggest that the wild V. cholerae strain, No. 31, produces a toxin identical to toxins previously reported in the literature and secretes it without accumulation in the cell, as is the case with other strains. However, strain No. 31's ability to nick the toxin is diminished compared with such abilities of other strains.