Binding and internalization of Clostridium perfringens iota-toxin in lipid rafts

Clostridium perfringens iota-toxin is a binary toxin composed of an enzymatic component (Ia) and a binding component (Ib). The oligomer of Ib formed in membranes induces endocytosis. We examined the binding and internalization of Ib by using Cy3-labeled Ib. Labeled Ib was retained at the membranes of MDCK cells for 60 min of incubation at 37 degrees C, and later it was detected in cytoplasmic vesicles. To determine whether Ib associates with lipid rafts, we incubated MDCK cells with Ib at 4 or 37 degrees C and fractionated the Triton-insoluble membranes. An Ib complex of 500 kDa was localized at 37 degrees C to the insoluble fractions that fulfilled the criteria of lipid rafts, but it did not form at 4 degrees C. The amount of complex in the raft fraction reached a maximum after 60 min of incubation at 37 degrees C. When the cells that were preincubated with Ib at 4 degrees C were incubated at 37 degrees C, the complex was detected in the raft fraction. The treatment of MDCK cells with methyl-beta-cyclodextrin reduced the localization of the Ib complex to the rafts and the rounding of the cells induced by Ia plus Ib. When 125I-labeled Ia was incubated with the cells in the presence of Ib at 37 degrees C, it was localized in the raft fraction. Surface plasmon resonance analysis revealed that Ia binds to the oligomer of Ib. We conclude that Ib binds to a receptor in membranes and then moves to rafts and that Ia bound to the oligomer of Ib formed in the rafts is internalized.     

CPT-11 hepatic arterial infusion chemotherapy for metastatic liver tumor from gastric cancer

We have experienced a case of gastric cancer with multiple liver metastases resistant to combined treatment of TS-1 and CDDP. After the treatment with TS-1 and CDDP, abdominal CT demonstrated a progressive growth of metastatic liver tumor. Administration of CPT-11 (80 mg/body) by a hepatic arterial infusion inhibited the growth of metastatic liver tumor and decreased serum levels of CEA and CA19-9 for several months without a significant adverse side effect.     

How xylitol-containing products affect cariogenic bacteria

BACKGROUND: The authors examined the effect of xylitol, a naturally occurring sweetener, on levels of Streptococcus mutans and S. sobrinus. They also investigated xylitol's mechanism of action. METHODS: The authors compared cariogenic bacteria levels before and after exposure to xylitol products in children and adults. In the first study, 187 children received xylitol-containing snacks in school for four weeks. In the second study, two adults received xylitol candy for four weeks. Unstimulated saliva samples were taken from all subjects. Gingival samples also were taken from the adults. The authors plated the samples on selective microbiological media. Individual isolates were plated on media with varying concentrations of xylitol, and were identified using specific DNA probes. Genetic relatedness was determined via pulse-field gel electrophoresis. RESULTS: The children's salivary S. mutans levels remained stable before and after xylitol exposure. Further analysis of the S. mutans isolates was conducted for seven children. Bacteria from five of these children grew with 10 percent or less xylitol at baseline, while the bacteria from all seven children grew with 15 percent xylitol after exposure to the xylitol-containing snacks, suggesting that the S. mutans increased in tolerance to xylitol during exposure. Six children had isolates with the same genotype at both time points. S. mutans and S. sobrinus levels were reduced in one of the adults as a result of xylitol exposure, and the bacterial isolates became more xylitol tolerant. In the second adult, S. mutans and S. sobrinus levels increased, while the subject maintained the same proportion of susceptible and tolerant strains as that at baseline. CONCLUSIONS: Overall, consumption of xylitol-containing snacks and candy did not reduce S. mutans levels. However, bacteria from five children and one adult became more xylitol tolerant. CLINICAL IMPLICATIONS: These results provide a basis on which xylitol-containing products can be recommended and xylitol's mechanism of action can be explained to patients.     

Successful management of traumatic aortic valve insufficiency; report of a case

A case of the successful management of traumatic aortic valve insufficiency is reported. A previously healthy 48-year-old man sustained multiple injuries in a traffic accident. One month after the accident, heart failure, derived from aortic insufficiency, was noted. Three years and 5 months after the injuries, aortic valve replacement was performed, and a large tear, approximately 7 mm in length, was found in the aortic right coronary cusp. This finding corresponded to the traumatic aortic valve insufficiency. Traumatic aortic valve insufficiency is rare, and early diagnosis may be difficult. Examinations for associated intracardiac injuries should be carefully undertaken.     

Interval-dependent potentiation of left ventricular contractility is preserved in patients with atrial fibrillation and depressed ejection fraction

Echocardiographic techniques were used to measure left ventricular isovolumic and ejection phase indexes of contractility in 54 patients with atrial fibrillation, and the relations between cycle lengths and contractility were compared in patients with normal and depressed ejection fractions. Data indicate that variations in contractility occur in a pattern that is consistent with postextrasystolic potentiation and that such interval-dependent potentiation is preserved in patients with atrial fibrillation and depressed ejection fraction.     

New method for thyroid transplantation across major histocompatibility complex barriers using allogeneic bone marrow transplantation

BACKGROUND: It has been shown that allogeneic bone marrow transplantation (BMT) after lethal irradiation elicits donor-specific tolerance for organ or tissue transplantation across major histocompatibility complex (MHC) barriers. Recently, we have demonstrated that the portal venous (p.v.) administration of donor bone marrow cells (BMCs) elicits donor-specific tolerance across MHC barriers by only two administrations of an immunosuppressant (CsA or FK-506). In our study, using the central and intrahepatic tolerance-inducing system, we have established a new method for thyroid transplantation with BMT that would be more applicable to humans. METHODS: In addition to sublethal (6-5 Gy) irradiation, recipient B6 (H-2b) mice received injections i.p. with the myeloablative drug busulfan (BU) on day -2 to provide a sufficient "space" for the donor hematopoietic cells to expand in the recipients. To induce the intrahepatic tolerance, donor BALB/c (H-2d) BMCs were treated with neuraminidase (Neu), which enhances the trapping of i.v. injected BMCs in the liver. After the injection of Neu-treated BMCs, the thyroid organs from the BALB/c mice were engrafted under the renal capsules. RESULTS: A 90% graft survival rate was obtained over 100 days by a combination of BU administration, 6 Gy irradiation, and i.v. injection of Neu-treated BMCs [BU+6 Gy+(Neu) i.v.], and a 70% graft survival rate was obtained by [BU+5 Gy+(Neu) i.v.]. However, the graft survival rate significantly decreased when either the BU or Neu treatment was omitted. T cells collected from the tolerant recipients suppressed the proliferative responses to donor alloantigens. CONCLUSIONS: Using both BU and Neu treatments, we have succeeded in inducing long-term tolerance and preventing the rejection of thyroid allografts by the single-day protocol.     

Intrabiliary administration of doxorubicin for pancreaticobiliary cancer

The effect and drug absorbtion of intrabiliary chemotherapy with Doxorubicin for pancreaticobiliary cancer with PTCD was investigated. Doxorubicin (DXR: 20 mg) was administered intrabiliary for 3 hours by PTCD catheter. Radiographic evaluation of the bile duct before and after chemotherapy and measurement of DXR concentration in the serum and bile were carried out. RESULTS: Intrabiliary administration of DXR was completed without any significant complications other than epigastric pain. Radiographic study of the bile duct of a patient with pancreatic cancer who could successfully complete DXR administration showed improvement of bile duct passage. The placement of biliary stent could be achieved. Concentration of DXR in the serum after administration was below the lowest determinable level while those in the bile maintained a considerably high concentration 4 hours after the administration. With negligible absorption from bile, intrabiliary chemotherapy with DXR was thought to be an acceptable palliative treatment for pancreaticobiliary cancer.     

Impaired nitric oxide-independent dilation of renal afferent arterioles in spontaneously hypertensive rats.

Sustained hypertension alters vasomotor regulation in various vascular beds. We studied whether nitric oxide (NO)-dependent and NO-independent vasodilator mechanisms are altered in renal microvessels in hypertension. To directly visualize the renal microcirculation, the isolated perfused hydronephrotic rat kidney model was used. After pretreatment with indomethacin (100 micromol/l), afferent arterioles were constricted by norepinephrine (NE) or by increasing renal arterial pressure (i.e., myogenic constriction; from 80 to 180 mmHg). Acetylcholine (ACH) was then added, and the renal microvascular response was assessed by computer-assisted video image analysis. A similar protocol was conducted in the presence of nitro-L-arginine methylester (L-NAME; 100 micromol/l). During NE constriction, ACH caused dose-dependent and sustained vasodilation of the afferent arteriole, similar in magnitude in Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). In the presence of L-NAME, ACH (0.01-1 micromol/l) elicited only transient dilation, and the degree of vasodilation was very low in SHR. During myogenic constriction, afferent arterioles from WKY and SHR kidneys responded to ACH with only transient vasodilation, which was unaffected by NO inhibition; the transient vasodilative responses elicited by ACH (0.1-1 micromol/l) were smaller in SHR than in WKY. In conclusion, ACH has both sustained and transient vasodilative effects on the afferent arteriole. Sustained vasodilation is attributed to NO generation, which is similar in WKY and SHR. In contrast, transient vasodilation, mediated by NO-independent vasodilator factors, is impaired in SHR. Deranged vasodilatory mechanisms in hypertension may disturb the renal microcirculation, which may result in renal injury.     

EFFICACY OF AZATHIOPRINE IN MILD OR MODERATE RELAPSE IN CROHN'S DISEASE: CLINICAL AND ENDOSCOPIC EVALUATION

Aim: The present study was aimed at evaluating the efficacy of azathioprine (AZA) in patients with active and relapsing Crohn's disease (CD) and the usefulness of endoscopy in this evaluation. Methods: The 53 patients with active CD treated with AZA at our hospital were subjected to the following retrospective analysis: (i) evaluation of the clinical efficacy of AZA through comparison of the Crohn's disease activity index (CDAI); (ii) analysis of the relationship of the clinical efficacy to the difference in the mean corpuscular volume (MCV); (iii) evaluation of mucosal healing through analysis of the scores of the endoscopic findings in 16 patients; and (iv) analysis of the relapse rate. Results: (i) Among the 53 patients, treatment was rated as having induced complete remission in 22.6%, as being effective in 41.5%, and as being ineffective in 13.3% of patients. The treatment was discontinued in 22.6% of patients. (ii) The post‐treatment MCV was significantly increased after treatment. (iii) When the ulcer score estimated after treatment was compared with that before the start of treatment, a significant improvement of the score was noted. (iv) When the non‐relapse rate after AZA therapy was calculated in the 41 patients followed up for 12 months, it was 84.8%. Conclusion: AZA was shown to cause endoscopic mucosal healing as well as clinical efficacy. In the present study, it was inferred that the efficacy of AZA therapy in CD patients is manifested clinically first and that mucosal healing is an effect that occurs later.     

DIAGNOSIS AND CLINICAL COURSE OF ULCERATIVE GASTRODUODENAL LESION ASSOCIATED WITH ULCERATIVE COLITIS: POSSIBLE RELATIONSHIP WITH POUCHITIS

Background and Aim: Ulcerative colitis (UC) is not only characterized by pathological lesions localized to colonic mucosa, but also to various complications involving other organs, including postoperative pouchitis. Among these complications, diffuse gastroduodenitis with lesions resembling colonic lesions has been reported, albeit rarely. The aim of the present study was to attempt to characterize the lesions of the upper gastrointestinal tract occurring as a complication of UC, and to assess the frequency and clinical course of these lesions. Methods: A total of 322 UC patients who had undergone upper gastrointestinal endoscopy were retrospectively analyzed. We assessed the frequency of endoscopic findings, including diffuse gastroduodenal lesions resembling colonic lesions. Ulcerative gastroduodenal lesion (UGDL) associated with UC was diagnosed if lesions satisfied the following criteria: (i) improvement of the lesions with treatment of UC; and/or (ii) resemblance to UC in pathological findings. Results: UGDL satisfying the aforementioned criteria was found in 15 (4.7%) of 322 patients. All the 15 patients had UGDL accompanied by pancolitis or after proctocolectomy. Frequency in 146 patients with pancolitis was 6.2% (nine patients) and that in 81 patients who had undergone proctocolectomy was 7.4% (six patients). Four patients with diffuse ulcerative upper‐gastrointestinal mucosal inflammation (DUMI) had pouchitis. In all patients except one, the lesions resolved easily with medical treatment. Conclusions: In more than half of the post‐proctocolectomy patients, UGDL was related to the occurrence of pouchitis. The existence of characteristic UGDL must be taken into account in the diagnosis and treatment of UC, and UGDL is possibly related to the occurrence of pouchitis.