Nitric oxide mediates mitochondrial dysfunction in hepatoma cells induced by non-activated Kupffer cells: evidence implicating ICAM-1-dependent process

The metabolic changes in a rat hepatoma cell line, AH70 cells, after co-culture with rat Kupffer cells (KC) were visualized and analysed using a fluorescence microscope equipped with a silicon intensified target camera and a laser scanning confocal microscopic system. Kupffer cells were isolated from male Wistar rats, and cultured without any stimuli. The non-activated KC reduced the mitochondrial energization in the cocultured AH70 cells within 2 h, which was indicated by decreased rhodamine 123 (Rh123) fluorescence. Either NG-monomethyl-L-arginine or dexamethasone significantly attenuated the KC-induced mitochondrial dysfunction in AH70 cells, suggesting the involvement of nitric oxide (NO) derived from inducible-type nitric oxide synthase (iNOS). Administration of monoclonal antibody (mAb) directed against rat ICAM-1 also prevented the decrease in Rh123 fluorescence. Electron microscopy revealed that the membrane-to-membrane attachment between KC and AH70 cells occurred within 2 h. A laser scanning confocal microscopic observation using mAb against ICAM-1 presented that the ICAM-1 expression on AH70 cells and KC increased after the co-culture. It is therefore concluded that the KC-mediated mitochondrial dysfunction of hepatoma cells largely depends on NO production by iNOS. Furthermore, the present study supports a scenario that the NO production and release from KC is triggered by the close contact with hepatoma cells through adhesion molecules such as ICAM-1.

Isolation and characterization of jararaca GPIb-BP, a snake venom antagonist specific to platelet glycoprotein Ib

A platelet glycoprotein Ib-binding protein (GPIb-BP) was isolated from the snake venom of Bothrops jararaca. Jararaca GPIb-BP showed a single band with M(r) of 30,000, and two distinct bands with M(r) of 17,000/13,000 under non-reducing and reducing conditions, respectively, on SDS-polyacrylamide gel electrophoresis. Jararaca GPIb-BP itself induced neither platelet aggregation nor serotonin release from platelets, but specifically bound to GPIb (40,629 +/- 2,521 molecules per normal platelet, with Kd 39.1 +/- 2.4 nM at saturation). The purified venom protein completely inhibited ristocetin- or botrocetin-induced von Willebrand factor (vWF) binding, and blocked the bovine vWF binding to GPIb, with IC50 values ranging from 28 to 42 nM, without affecting the platelet aggregation induced by ADP or alpha-thrombin. 125I-jararaca GPIb-BP binding to GPIb was not altered by the presence of human alpha-thrombin. Jararaca GPIb-BP at a final concentration of 104 nM totally abolished vWF-dependent shear-induced platelet aggregation (SIPA) at a high shear stress, but had no effect on SIPA at a low shear stress. Reduced and S-carboxyamido-methylated jararaca GPIb-BP lost its inhibitory activity on SIPA. The NH2-terminal amino acid sequences of the subunits revealed a high degree of homology with those of several Ca(2+)-dependent lectins, especially to those of two functionally opposite venom proteins, botrocetin (a vWF-modulator) and alboaggregin-B (a GPIb-modulator).

[Syringomyelia associated with tentorial meningioma]

A 28-year-old male was admitted to our hospital with the complaints of numbness of the left upper limb and gait disturbance. Neurological examination disclosed slight left dysmetria, truncal ataxia and sensory disturbance at the dermatome of C8 and Th1. CT and MRI scans showed a large mass lesion in the left posterior fossa, ventricular dilatation, cavum septi pellucidi and cavum Vergae, empty sella, cervical syringomyelia and left tonsilar herniation. The tumor which attached to cerebellar tentorium was totally removed and a histological diagnosis of meningothelial meningioma was made. Postoperative MRI scan demonstrated a disappearing of syringomyelia with the improved tonsillar herniation. Association of syringomyelia with brain tumor is relatively rare, so its pathogenesis was discussed.

Subcellular localization of the APC protein: immunoelectron microscopic study of the association of the APC protein with catenin

Mutations in the APC gene are linked to the development of sporadic colorectal tumors as well as to familial adenomatous polyposis. Recently, the APC protein was reported to associated with catenins, proteins that bind to the cell adhesion molecule E-cadherin. In the present study, we examined the distribution and localization of the APC protein and alpha -catenin in the normal mouse intestine by light and immunoelectron microscopy using specific antibodies. The APC protein was found to be localized in microvilli and in the apical and lateral cytoplasm of the epithelial cells, whereas alpha-catenin was detected only in the lateral cytoplasm. Double-labeling immunoelectron microscopy showed colocalization of the APC protein with alpha-catenin in the lateral cytoplasm, especially along the lateral plasma membrane, although a certain portion of the APC protein in this region was distributed independently of alpha-catenin. These results suggest that a portion of the APC protein localized in the lateral cytoplasm of intestinal epithelial cells functions in cooperation with catenins, whereas the APC protein in microvilli and in the apical cytoplasm has other functions independent of catenins.

Gastric microcirculatory disturbance and behaviour of leucocytes after thermal injury: intravital observation of arteriovenous shunting channels in the gastric submucosal layer

In order to investigate the pathogenesis of acute gastric mucosal lesion after thermal injury, microcirculatory disturbance was assessed and observation of the behaviour of leucocytes was performed. Gastric blood flow decreased at 15 min post-thermal injury, and partially improved at 2 h; however, it decreased again at 5 h post-thermal injury. Mucosal microcirculatory disturbance was observed by using vascular labelling with monastral blue B. Deposits of monastral blue B were observed centring mainly on collecting venules but were also observed in the capillaries. Submucosal microcirculatory disturbance was observed through an intravital microscope. The irregularity of the wall and segmental constriction in the venules and presence of an arteriovenous shunting channel was observed in the submucosal layer at 5 h post-thermal injury. The percentage of rolling or sticking leucocytes that passed the confluence of a prevenule and a venule were significantly increased at 5 h after thermal injury. The present study revealed depression of gastric blood flow, mucosal and submucosal microcirculatory disturbance, and a significant increase of rolling and sticking leucocytes in the peripheral part of venules after thermal injury. Leucocyte-endothelial interactions may occur under such conditions and this interaction may play an important role in inducing the microcirculatory disturbance that results in an acute gastric mucosal lesion after thermal injury. The present study also demonstrated the possibility of intravital study of gastric submucosal arteriovenous shunting channels.

Human cortical regions activated by wide-field visual motion: an H2(15)O PET study

1. Several areas in the monkey dorsal visual pathway, including the dorsal part of the medial superior temporal area, have been found to contain cells responding to movements of a wide visual field and are suggested to be involved in analyzing self-induced motion information. In the present study, positron emission tomography was used to localize human cortical regions responding to wide-field visual motion. Changes in regional cerebral blood flow (rCBF) were measured when subjects maintained fixation and viewed low-contrast (0.15 log units brighter than the background) dots subtending 80 x 80 degrees and moving either coherently or incoherently. Brain foci were localized after activity in a fixation-only paradigm was subtracted from that in the two moving dot paradigms. 2. Both the coherent and incoherent movements significantly activated the primary/secondary visual cortex and surrounding visual areas in the cuneus and superior occipital gyrus. Subtraction of images between the coherent and incoherent movements showed that the activity caused by the two types of movement was comparable in these early visual cortical regions. 3. In the lateral occipitotemporoparietal cortex, the coherent movement specifically activated two separate areas; a posterior focus was located at the border of the right occipitotemporal gyri, and a dorsoanterior focus was located bilaterally in the temporoparietal cortex. The incoherent movement did not activate these regions. 4. A fine anatomic localization using individual magnetic resonance images was performed for the bilateral activation in the temporoparietal cortex, which was found to be located mainly in the depth of the inferior parietal lobule and a small portion of the superior and middle temporal gyri. 5. Both the coherent and incoherent movements activated a part of the superior parietal lobule located within the intraparietal sulcus (Brodmann area 7). The bilateral foci activated by the coherent movement were located more anteriorly than the focus activated by the incoherent movement. Subtraction images between the coherent and incoherent movements, however, did not reveal any significant rCBF increases in the superior parietal lobule. 6. Several other cortical regions known to be involved in visuospatial and visuomotor functions were also activated by the coherent movement, including the frontal eye field (Brodmann area 8) and premotor cortex (Brodmann area 6) in the frontal lobe. 7. The posteriorly located activation at the border of occipito-temporal gyri corresponds to the homologue of the middle temporal area reported in previous activation studies using small to medium-sized motion stimuli. The bilateral activation in the inferior parietal lobule appeared to rely on wide-field motion stimulation.

Aging effect on neutral amino acid transport at the blood-brain barrier measured with L-[2-18F]-fluorophenylalanine and PET

Neutral amino acids (NAAs) are transported from the blood to the brain using the same carrier system in a competitive fashion. The purpose of this study is to establish a method for evaluating neutral amino acid transport at the blood-brain barrier (BBB) in humans and to examine the aging effect of amino acid transport.

METHODS

A dynamic PET study with L-(2-18F)-fluorophenylalanine (18F-Phe) was performed in 14 normal volunteers (age 21-71 yr; mean +/- s.d., age range 48.0 +/- 17.1 yr). By using a two-compartment model analysis and a weighted integration technique, the influx rate constant K1, the efflux rate constant k2 and distribution volume Vd of 18F-Phe were estimated in various brain structures.

RESULTS

The value of K1 was inversely correlated with plasma NAA concentration (r = -0.69, p < 0.01). The cerebellum showed the highest value of K1, while the white matter showed the lowest. There was no significant change in K1 during aging. The value of k2 was significantly increased with age.

CONCLUSION

No decline of K1 during aging indicated that NAA transport from the blood to the brain is a limiting process of age in amino acid incorporation. Fluorine-18-Phe PET imaging is a feasible method to study NAA transport at the BBB in vivo in humans and can be applied to pathological conditions of the brain.

Altered expression of hepatic CYP1A enzymes in rat hepatocarcinogenesis

Hyperplastic nodules of the liver were induced by treating male F344 rats with a combination of diethylnitrosamine and partial hepatectomy. The livers were examined for the expression of cytochrome P450 (CYP) enzymes, mainly CYP1A1 and CYP1A2; the amount and activity of the enzymes in the microsomes were assessed by enzymatic and immunological methods. Levels of CYP1A mRNAs were assayed by Northern blotting. In the liver bearing hyperplastic nodules, the total amount of microsomal CYP enzymes decreased to about 50% of the control. The microsomal activities for the CYP1A2-mediated activation of carcinogenic heterocyclic amines decreased to about 20% of the corresponding controls, in association with decreases in the levels of mRNA and protein of CYP1A2. Furthermore, the inducibility of CYP1A2 by CYP1A inducers such as 3-methoxy-4-aminoazobenzene and 3-methylcholanthrene was also decreased at the mRNA, protein and activity levels. On the other hand, CYP1A1 enzyme, which was undetectable in control rat liver, appeared in the liver bearing hyperplastic nodules, but its inducibility by a CYP1A inducer decreased slightly. The present findings indicated that individual CYP1A enzymes are differently regulated, and the expression of CYP1A2 is reduced preferentially in the liver bearing hyperplastic nodules.

Conjugated bile salts regulate turnover of rat intestinal brush border membrane hydrolases

The mechanisms whereby the conjugated bile salts regulate the activities of the brush border membrane hydrolases and its physiological significance were investigated in rat small intestine, and comparisons were made with the action of pancreatic protease. Rat brush border membrane proteins were metabolically labeled with [35S]methionine, and isolated brush border membrane was incubated with taurocholate or pancreatic elastase. The activity of solubilized hydrolases was assayed and the molecular forms of the hydrolases were examined by SDS-PAGE. The activity and protein bands of alkaline phosphatase and sucrase-isomaltase were solubilized by taurocholate, while alkaline phosphatase was not solubilized by elastase. Solubilized sucrase-isomaltase molecules were proteolytically degraded by elastase, whereas the intact molecule of sucrase-isomaltase was solubilized by taurocholate. Next the physiological role of bile salts in brush border membrane hydrolase turnover were investigated using metabolic labeling of brush border membrane hydrolase and immunoprecipitation in biliary diversion rats. After three days of biliary diversion, a significant increase in alkaline phosphatase activity was observed. Although synthesis of alkaline phosphatase in biliary diversion rats was similar to that observed in control rats, biliary diversion rats showed 1.5-fold slower turnover of alkaline phosphatase when compared with control rats. These results suggest that conjugated bile salts in the intestinal lumen may cause a rapid turnover of brush border membrane hydrolases, which may be increased by the enhanced enzyme degradation. The mechanisms for the enhanced degradation appeared to be solubilization of hydrolases caused by the detergent activity of bile salts. Therefore, conjugated bile salts may play an important physiological role in the regulation of expression of the protease-resistant enzymes such as alkaline phosphatase.

Activation of renal dopamine system by physical exercise

Physical exercise is one of the life-style modifications used for lowering blood pressure. Except for diminished norepinephrine spill over, the mechanism by which physical exercise exerts its effects was not known. Based on our preliminary finding that the reduction of blood pressure was inversely correlated to the baseline plasma renin activity, we have consequently revealed that mild exercise reduces plasma volume and hence the cardiac index. In order to elucidate the mechanism, we have investigated all possible parameters relevant to plasma volume regulation. Among them, urinary free dopamine and urinary active kallikrein increased in the early stages (weeks 2-4) while atrio-natriuretic factor (week 4) and endogeneous ouabain-like substance (EOLS) consequently (weeks 7-10) decreased. Serum taurine increased and plasma norepinephrine decreased in the late stages. The conclusion reached is that mild exercise seems to first activate the renal dopamine and kallikrein systems and second trigger other mechanism, such as an increase in taurine and decreases in EOLS and norepinephrine.

Spatial heterogeneity of mucosal blood flow during ischemia-reperfusion injury of rat stomach investigated by laser Doppler perfusion imaging

Spatial alterations in blood flow during the development of mucosal injury induced by ischemia-reperfusion in rats were determined with a two-dimensional laser Doppler tissue perfusion imager. The rats were anesthetized with pentobarbital, and the stomach was exteriorized on a stage; the mucosa was then sequentially scanned. The mucosa was constantly superfused with 0.1 N HCl in physiological saline. Systemic arterial pressure was continuously monitored and blood was stepwisely withdrawn from the femoral artery by 20-mmHg stage and then maintained at 20 mmHg for 20 min. The shed blood was reinfused and the stomach was removed 30 min later. Under control conditions, the average perfusion of the forestomach was usually greater than that in the glandular stomach. When systemic blood pressure was stepwisely decreased, the extent of decrease in the mucosal blood perfusion unit was always greater than that in systemic blood pressure, but mucosal perfusion appeared to be uniformly decreased throughout the stomach. Ten min after reperfusion, a hypoperfused area began to appear in the corpus near the greater curvature, and this area subsequently increased. The area of ulcer formation corresponded with the hypoperfused area in the gastric mucosa 30 min after reperfusion. Pretreatment with CV-6209, a platelet-activating factor antagonist, significantly attenuated the hypoperfusion induced by reperfusion and also prevented gastric mucosal damage. Our results suggest that hypoperfusion in the mucosal microcirculation is indeed an important factor contributing to the localized occurrence of gastric mucosal lesions and that the laser Doppler perfusion imager is useful for the detection of local hypoperfused areas in the gastric mucosa.

Plasma free and sulfoconjugated dopamine before and after a half-marathon

To elucidate whether increased plasma levels of free dopamine (F-DA) after exercise are due to deconjugation of sulfoconjugated (S-) DA in plasma, we compared the changes in plasma F- and S- DA, as well as changes in both the S- and F- forms of epinephrine (E) and norepinephrine (NE), after running a half-marathon. Free catecholamines (F-CAs) were measured by automated high-performance liquid chromatography (HPLC). Total (F+S) CAs were determined using an efficient deconjugation method as follows; 1200 microliters plasma was incubated with 152 mU arylsulfatase (AS) for 30 min at pH 7.6. The plasma levels of F-CA (pg/ml) (mean +/- SEM) all increased significantly (p < 0.01) after the half-marathon; i.e., F-DA increased from 13.3 +/- 5.7 to 176.3 +/- 32.2; F-E from 58.0 +/- 12.3 to 764.3 +/- 136.4; F-NE from 246.6 +/- 15.2 to 3082.0 +/- 690.3. OF S-CAs, S-E (from 127.8 +/- 26.0 to 1218.2 +/- 190.8) and S-NE (from 717.1 +/- 61.6 to 5586.9 +/- 761.9) also increased, but, in contrast, among the S-CAs, only the increase in S-DA (from 5324.9 +/- 1967.3 to 7359.6 +/- 1627.9) was not statistically significant. Sulfoconjugation may play an important role in inactivating F-DA as well as F-NE and -E, that are released into plasma in response to vigorous exercise. Thus, plasma F-DA is unlikely to be derived through deconjugation of plasma S-DA.

Macroscopic observations of mammary glands and teats of Japanese serows, Capricornis crispus, with special reference to past gestation

Mammary glands and teats were examined to estimate the reproductive history of Japanese serows. The presence of milk was an indicator of reproduction in the previous year. The thickness of the mammary glands is indicative of their function. The females whose mammary glands are more than 10 mm thick may be regarded as having delivered half a year before. The distance between teats is not always indicative of the function of the mammary glands. Animals with teats 10 mm or less in length and those with teats longer than 10 mm may be judged to be nulliparous and multiparous, respectively.

Formation of oligosaccharides from lactose by Bacillus circulans beta-galactosidase

Eleven oligosaccharides formed by a transglycosylation reaction during lactose hydrolysis with Bacillus circulans beta-galactosidase were purified by gel permeation chromatography, charcoal chromatography, and HPLC. From the results of methylation analysis, and MS and NMR studies, it was concluded that these oligosaccharides were beta-D-Galp-(1-->3)-D-Glc, beta-D-Galp-(1-->6)-D-Glc, beta-D-Galp-(1-->2)-D-Glc, beta-D-Galp-(1-->4)-beta-D-Galp-(1-->4)-D-Glc, beta-D-Galp-(1-->6)-[beta-D-Galp-(1-->2)]-D-Glc, beta-D-Galp-(1-->6)-[beta-D-Galp-(1-->4)]-D-Glc, beta-D-Galp-(1-->4)-beta-D-Galp-(1-->3)-D-Glc, beta-D-Galp-(1-->4)-beta-D-Galp-(1-->2)-D-Glc, beta-D-Galp-(1-->4)-[beta-D-Galp-(1-->2)]-D-Glc, beta-D-Galp-(1-->4)-beta-D-Galp-(1-->6)-D-Glc, beta-D-Galp-(1-->6)[beta-D-Galp-(1-->3)]-D-Glc. The last five are newly observed oligosaccharides. The results of a use test (in vitro) by human intestinal bacteria showed that the oligosaccharides containing lactose units were predominantly used by human intestinal bifidobacteria.

Efficacy of slow-releasing anticancer drug delivery systems on transplantable osteosarcomas in rats

New drug delivery systems for cis-diamminedichloroplatinum (CDDP) incorporated into vehicles, such as polymethylmethacrylate (PMMA), fibrin glue (F.G.), alpha-tricalciumphosphate (TCP) and ethylenevinyleacetate copolymer (Polymer) were examined using a rat osteosarcoma model. The materials containing CDDP were directly implanted into the tumors or subcutaneous tissue of rats, and the inhibitory effects on tumor growth and lung metastasis were evaluated. Data on in vitro kinetics of CDDP release revealed good results for both TCP and F.G., and the release pattern from TCP to be most appropriate for a slow-releasing drug delivery system. This was supported by the results of the implantation experiments, whereby the direct implantation of TCP containing CDDP (CDDP-TCP) into tumors, gave significantly better inhibitions of tumor growth and metastasis than either non-treatment (P < 0.01) or subcutaneous implantation (P < 0.05). In a second experiment, using different administration procedures, different inhibitory effects on tumor growth and lung metastatic potency were observed with intra-arterial and intravenous CDDP administration, as well as with CDDP-TCP implanted subcutaneously. Suppression effects of CDDP (10 mg/kg)-TCP directly implanted into tumors were equal to those of intra-arterial (2.5 mg/kg) and intravenous (5.0 mg/kg) administrations. The present results suggest CDDP-TCP implantation to be effective as a slow-release drug delivery system for inhibiting tumor growth and metastasis, and that it should be a useful adjuvant to conventional i.v. or i.a. chemotherapy.

Biochemical and molecular characterization of nucleoside triphosphate hydrolase isozymes from the parasitic protozoan Toxoplasma gondii

We have previously reported the presence of a novel nucleoside triphosphate hydrolase (NTPase) in the rapidly multiplying tachyzoite form of a virulent strain (RH) of Toxoplasma gondii. On further examination, it was found that the purified enzyme was not a single enzyme but was a mixture of two isozymes termed NTPase-I and NTPase-II. The two isozymes had similar molecular masses of approximately 240-270 kDa by gel filtration and contained four identical subunits of molecular mass 66-67 kDa by SDS-polyacrylamide gel electrophoresis. Both forms of the NTPase were activated by dithiothreitol, and NTPase-I had a specific activity 4.5-fold higher than NTPase-II in hydrolysis of ATP. The primary difference between these isozymes lies in their ability to hydrolyze nucleoside triphosphate versus diphosphate substrates. While NTPase-II hydrolyzed ATP to ADP and ADP to AMP at almost the same rate, NTPase-I hydrolyzed ADP to AMP at a much slower rate (0.7% of the rate for ATP). The complete cDNAs for NTPase-I and NTPase-II were sequenced and found to encode the same size predicted open reading frame of which only 16 of 628 amino acids differed between the two isozymes. Both forms of the NTPase contained an NH2-terminal hydrophobic signal peptide, consistent with our previous findings that these enzymes are secreted into the host cell vacuole occupied by the parasite. The gene encoding NTPase-II was found in all strains of Toxoplasma, while the NTPase-I was confined only to virulent strains. Expression of this highly active ATPase (NTPase-I) may contribute to intracellular survival and virulence of T. gondii.

Protein tyrosine phosphorylation in human platelets induced by interaction between glycoprotein Ib and von Willebrand factor

The interaction between von Willebrand factor (vWF) and glycoprotein Ib (GPIb) induced by ristocetin or botrocetin resulted in associated platelet aggregation, protein tyrosine phosphorylation (PTP) of a 64 kDa protein, as detected by a monoclonal antibody against phosphotyrosine (PY-20), and intracellular Ca2+ elevation that is largely dependent upon Ca2+ influx in human platelets. It is of interest that 75-80, 97 and 125 kDa proteins which are strongly tyrosine-phosphorylated in platelet activation induced by thrombin and other agonists were not detected. Neither vWF nor a coaggregating agent (ristocetin or botrocetin) alone induced aggregation, [Ca2+]i elevation or the 64 kDa PTP. NMC-4, an antibody which inhibits both ristocetin- or botrocetin-induced vWF binding to GPIb, abolished the appearance of the 64 kDa PTP as well as other responses, suggesting that it is specifically induced by the GPIb-vWF interaction. Aspirin, or ONO-3708, a competitive inhibitor of thromboxane A2, did not modify the 64 kDa PTP, while [Ca2+]i elevation was moderately suppressed. Depletion of extracellular Ca2+ or RGD peptides suppressed neither the 64 kDa PTP nor aggregation. H-7, a protein kinase C inhibitor, did not inhibit the 64 kDa PTP, while staurosporine, a potent protein kinase inhibitor, inhibited the 64 kDa PTP and Ca2+ influx, but not aggregation, in a dose-dependent manner. It is suggested that the 64 kDa PTP is associated with platelet aggregation induced by the interaction between GPIb and vWF.

Efficacy of the angiogenesis inhibitor O-(chloroacetyl-carbamoyl)fumagillol (AGM-1470) on osteosarcoma growth and lung metastasis in rats

The efficacy of the anti-angiogenic agent, O-(chloroacetyl-carbamoyl)fumagillol (AGM-1470), against primary tumor growth and spontaneous lung metastasis was evaluated experimentally using a transplantable osteosarcoma line in rats previously established in our laboratory. Male Fischer 344 rats bearing the tumor with a high potential for metastasis received intermittent or continuous subcutaneous administrations of AGM-1470. Both treatment regimens resulted in significant inhibitions of spontaneous lung metastasis and primary tumor growth in a dose-dependent manner, with continuous administration of AGM-1470 exerting the most pronounced inhibitory effects on both parameters.

Clinicopathologic studies of immunologic fecal occult blood test for colorectal cancer

In our hospital, 83 patients with colorectal cancer underwent the immunologic fecal occult blood test (IFOBT). The positive rate for IFOBT in all patients was 87%. Colon cancers more proximal than the transverse colon were 100% positive. Carcinomas of the ulcerative type showed a significantly higher positive rate than those of the non-ulcerative type (94% vs 73%). Carcinomas penetrating the muscularis or beyond showed a significantly higher positive rate, of 96% (52/54 cases) compared to carcinomas confined to the mucosa or submucosa, which gave positive rates of 64% and 60%, respectively. In the investigation of the 7 patients with colorectal cancer who showed negative results on the IFOBT, IFOBT had been performed only once in of these patients. Accordingly, it was considered necessary to perform IFOBT more than once. The cancers in 5 of these 7 patients were found to be carcinomas confined to the mucosa. This result suggests the advisability of annual IFOBTs. It is also considered necessary to manage patients who show undefinable but possibly positive (+/-) results with caution.

Human urinary kallikrein can generate angiotensin II from homologous renin substrates

We previously proposed the "kinin-tensin system," a unique vasoregulatory system that can produce both angiotensin II and kinins. To verify whether tissue kallikrein is a part of this system in humans, we examined the ability of human urinary kallikrein (HUK) to generate angiotensin (ANG) II directly from homologous renin substrates such as purified human angiotensinogen (AOGEN) and authentic human tridecapeptide renin substrate (13 RS). HUK released ANG II not only from ANG I but also directly from both AOGEN and 13RS at an optimum pH of 7.0. The amount of generated ANG II from 7.5 nmol of each of the three substrates at pH 7.0 was as follows: ANG I, 292.7 +/- 67.2; 13 RS, 1951.7 +/- 239.6; AOGEN, 2.2 +/- 0.3 (pmol/3h, n = 3 mean +/- SE). HUK cleaved Phe-His and His-Leu bonds in 13 RS, and Tyr-Ile and Phe-His bonds in ANG I. These results suggest that HUK is a part of the "kinintensin system", i.e., HUK can not only release kinins, but can also generate ANG II mainly through ANG I conversion and from AOGEN, the latter being a minor source of ANG II. Furthermore, HUK may play a role in regulating vascular tone under certain conditions in vivo.

Isolation and amino acid sequences of two trypsin inhibitors from the seeds of bitter gourd (Momordica charantia)

Two novel trypsin inhibitors, MCTI-II' and BGIT, were isolated from the seeds of bitter gourd (Momordica charantia) and their amino acids sequenced. MCTI-II' was a squash type trypsin inhibitor and lacked the N-terminal arginine residue of Momordica charantia trypsin inhibitor (MCTI)-II. It consists of 27 amino acid residues and forms a dimeric structure. BGIT had 88% homology with bitter gourd inhibitor against an acidic amino acid-specific endopeptidase (BGIA) consisting of 68 amino acid residues and inhibited not only trypsin but also subtilisin Carlsberg. The amino acid replacements occurred in 8 positions of which that of Gln2 by Arg or of Ala44 by Lys is suggested to be responsible for the trypsin-inhibitory action of BGIT. Inhibitory activity of BGIT for trypsin was greatly decreased by acetylation, while that for subtilisin was slightly increased. From these results and the sequence comparison with eglin-c superfamily inhibitors, the reactive site of BGIT is assumed to be Lys44.

Fibronectin and 130-kDa molecule complex mimics snake venom botrocetin-like structure potentially modulating association between von Willebrand factor and vascular vessel wall

We established seven hybridomas secreting monoclonal antibodies (MoAbs) against the venom from Bothrops jararaca. Six of them were demonstrated to specifically recognize botrocetin, a venom protein which binds with von Willebrand factor (vWf) and induces platelet agglutination. Two of them, BCT4-3 and BCT115-2 MoAbs, could significantly inhibit botrocetin binding with plasma vWf. BCT4-3 could react slightly with a monolayer of human endothelial cells (ECs), and BCT4-3 binding to ECs was drastically enhanced by the coexistence of human plasma in a dose-dependent manner, indicating that a biological modulator structurally resembling botrocetin is created initially on the EC surface complexed with some plasma proteins. Botrocetin-like components could be immuno-purified only by immobilized BCT4-3, but not by the other immobilized MoAbs, from umbilical vein extracts. Interestingly, the immunoisolated materials were identified to consist essentially of fibronectin (Fn) and a 130 kDa molecule, and this complex bound to vWf in the extracts. Depletion of Fn from plasma decreased BCT4-3 binding to ECs. The epitope of BCT4-3 expressed on the endothelial surface, comprising plasma Fn and the coisolated 130 kDa molecule, is proposed to be a physiological modulator structurally mimicking botrocetin, and essentially supporting vWf-binding to injured endothelium and subsequently to circulating platelets.