NMDA receptors are important for both mechanical and thermal allodynia from peripheral nerve injury in rats

Previous studies showed that heat-hyperalgesia and mechanical allodynia produced by chronic constrictive injury of the sciatic nerve were differentially sensitive to the NMDA receptor antagonist dextrorphan and to morphine and other opioid receptor agonists. These results support the hypothesis that different kinds of neuropathic pain symptoms are caused by different pathological mechanisms. In the present study we determined whether mechanical and thermal allodynia produced by unilateral transection of the 'superior' caudal trunk which innervates the tail in rats were differentially sensitive to the non-competitive NMDA receptor antagonist MK-801. Injection of MK-801 (0.3 mg/kg, i.p.) prior to nerve injury delayed the emergence of both types of allodynia; the antagonist-treated rats exhibited neither mechanical nor thermal allodynia at least for 4 days after the injury, whereas untreated control rats exhibited clear signs of allodynia from the first day after the injury. MK-801 injection on post-injury day 14, when the allodynia was near peak severity, suppressed temporarily both the mechanical and thermal allodynia. These results suggest that the mechanical and thermal allodynia from partial denervation of the tail are both dependent on NMDA receptors in their induction and maintenance. Thus, our results do not support the notion that different pathological mechanisms underlie different modalities of neuropathic pain from partial peripheral nerve injury.

Oriented DNA binding by one-armed lambda repressor heterodimers and contacts between repressor and RNA polymerase at P(RM)

Bacteriophage lambda repressor activates transcription from P(RM) by contacting the sigma subunit of E. coli RNA polymerase. Although mutations in repressors that are defective in activation affect exposed residues in the repressor-operator co-crystal, the subunit in repressor dimers that is responsible for activation has not been determined experimentally. Here, we describe an oriented heterodimer approach using one-armed repressor-leucine zipper fusion proteins to resolve this question. Protection against methylation of operator DNA in vitro by one-armed and two-armed repressor-leucine zipper heterodimers shows that the subunit containing the arm in a one-armed repressor heterodimer binds preferentially in the consensus half-site of lambda operators. The patterns of activation of the P(RM) promoter in vivo by one-armed heterodimers containing the pc2 mutation in only one subunit show that RNA polymerase at P(RM) contacts the N-terminal domain of the promoter-proximal subunit of the repressor dimer.

Cells in pseudointimal hyperplasia is migrated from extravascular space

BACKGROUND

The aim of this study was to investigate the origin of the pseudointima (PI) formed in polytetrafluoroethylene (PTFE) tube grafts after implantation into the inferior vena cava (IVC) of rabbits.

METHODS

A segment of the IVC of rabbits was replaced by PTFE tube graft (3 cm long, 3 mm inner diameter, 30 microns internodal distance, 0.3 mm thickness). The experimental group was divided into two groups as follows: (Group A) non-wrapped, (Group B) wrapped the outer wall of PTFE with impermeable vinyl.

RESULTS

Grafts were harvested at three weeks after implantation and subjected to the following studies: patency, ultrastructural studies by light microscopy (LM) and immunostaining, scanning and transmission electron microscopy (SEM & TEM). The grafts were patient but the lumen of the control group was narrowed by PI. LM and immunostaining studies revealed the presence of thick PI composed of spindle-type cells in Group A, bust almost no PI in Group B. Only few erythrocytes, macrophage and protein-fibrin matrix was found in Group B. Endothelial like cell coverage, judged by SEM, was observed in only Group A. Only some macrophages and platelets were shown in the graft surface in Group B. TEM of PI revealed the presence of VSMCs, myofibroblasts and outer surface of grafts revealed the presence of myofibroblast in Group A.

CONCLUSIONS

The formation of PI suppressed by blocking the cellular migration from perigraft space suggest that PI was mainly originated by myofibroblast located in the perigraft space.

Sarcomatoid hepatocellular carcinoma with osteoclast-like giant cells: case report and immunohistochemical observations

Hepatocellular carcinoma (HCC) with osteoclast-like giant cells (OGC) developed in the cirrhotic liver of a 42-year-old male. Serum protein induced by vitamin K absence or antagonist II was elevated preoperatively. The patient died of the disease on the 28th postoperative day. Histologically, the tumor consisted of OGC and mononuclear cells (MC). The OGC were characterized by benign-appearing nuclei, whereas the MC had atypical nuclei with a considerable number of mitoses. A vaguely trabecular pattern was observed in the focal area of the tumor, but no evidence of overt HCC was found. Immunohistochemical analysis revealed that both OGC and MC were diffusely positive for histiocytic and mesenchymal markers. Some MC were focally positive for cytokeratins 7, 8 and 19, and for albumin. Our clinical, histological and immunohistochemical findings suggest that the MC were derived from hepatocytes, with some mesenchymal features, but the OGC were non-neoplastic and reactive histiocytes.

Genetic evidence for the multicentric origin of synchronous multiple gastric carcinoma

Multiple gastric cancers, which constitute 4% to 10% of all gastric cancers, occur in older people and are associated with more extensive intestinal metaplasia. With regard to the genesis of multiple gastric cancers, multicentricity (independent origin) rather than multifocality (local or lateral spread of one cancer) has been the favored theory. Conventional morphologic study, however, has not been able to provide convincing evidence in support of multicentricity. The purpose of this study was to verify the multicentric origin of multiple gastric cancers at a genetic level. For this purpose, immunohistochemical and molecular techniques were used to define the mutation pattern of APC, MCC and p53 in multiple lesions of synchronous multiple gastric cancers. The study was based on a total of 30 gastric tumors from 13 patients, including 10 double tumors, 2 triple tumors, and 1 quadruple tumor. Single-strand conformation polymorphism and polymerase chain reaction direct sequencing were carried out for exons 5 to 8 of p53, and loss of heterozygosity was detected on the basis of polymerase chain reaction amplification of polymorphism in exon 10 of MCC and in exon 11 of APC. Twelve of 13 cases showed alteration in one or more genetic markers. Of these, three demonstrated a discordant mutation pattern of p53 in individual lesions, and another two revealed allelic loss of MCC in one lesion and p53 mutation in the other. In six other cases, only one lesion showed alteration of APC, MCC, or p53, and in the remaining case, one lesion carried p53 and MCC mutations and the other carried MCC loss of heterozygosity only. The results of this study showed discordance of the mutation pattern of APC, MCC, and p53 in individual lesions of multiple gastric cancers, providing genetic evidence for a multicentric origin of synchronous multiple gastric carcinomas. Collectively, these findings supported the theory of field cancerization in gastric carcinogenesis.

The antihypertensive effect of orally administered nifedipine-loaded nanoparticles in spontaneously hypertensive rats

1. The therapeutic use of nifedipine is limited by the rapidity of the onset of its action and its short biological half-life. In order to produce a form devoid of these disadvantages we made nanoparticles of nifedipine from three different polymers, poly-epsilon-caprolactone (PCL), polylactic and glycolic acid (1:1) copolymers (PLAGA), and Eudragit RL/RS (Eudragit). Nifedipine in polyethylene glycol 400 (PEG) solution was used as a control. 2. The average diameters of the nanoparticles ranged from 0.12 to 0.21 micron; the encapsulation ratio was 82% to 88%. 3. In spontaneously hypertensive rats (SHR), the initial rapid fall in systolic arterial blood pressure following oral administration of nifedipine in PEG solution (from 193 +/- 3 to 102 +/- 2 mmHg) was not seen following administration of the same dose in Eudragit nanoparticles (from 189 +/- 2 to 156 +/- 2 mmHg); with PCL and PLAGA nanoparticles the initial fall in blood pressure was significantly reduced (nadirs PCL 124 +/- 2 and PLAGA 113 +/- 2 mmHg). Ten hours following administration, blood pressure in rats administered the nifedipine/PEG preparation had returned to normal (183 +/- 3 mmHg) whereas that of animals given nifedipine in nanoparticles (PCL 170 +/- 3, PLAGA 168 +/- 2, Eudragit 160 +/- 3 mmHg) was still significantly reduced. 4. All of the nanoparticle dosage forms decreased Cmax and increased Tmax and the mean residence time (MRT) values. Relative bioavailability was significantly increased with Eudragit nanoparticles compared to the nifedipine/PEG solution. 5. There was an inverse linear correlation between the fall in blood pressure and plasma nifedipine concentration with all preparations. 6. The nanoparticle nifedipine preparations represent sustained release forms with increased bioavailability, a less pronounced initial antihypertensive effect and a long-lasting action.

ICG clearance in assessing cirrhotic patients with hepatocellular carcinoma for major hepatic resection

Objective: To deWne the safety of major hepatectomy for hepatocellular carcinoma (HCC) associated with cirrhosis and the selection criteria for surgery in terms of hospital mortality.

Design: Major hepatectomy for HCC in the presence of cirrhosis is considered to be contraindicated by many surgeons because the reported mortality rate is high (26% to 50%). Previous workers recommended that only selected patients with Child's A status or indocyanine green (ICG) retention at 15 minutes of less than 10% undergo major hepatectomy. A survery was made, therefore, of our patients with HCC and cirrhosis undergoing major hepatectomy between 1989 and 1994.

Setting: A tertiary referral center.

Patients: The preoperative, intraoperative, and post-operative data of 54 patients with cirrhosis who had major hepatectomy were compared with those of 25 patients with underlying chronic active hepatitis and 22 patients with normal livers undergoing major hepatectomy for HCC. The data had been prospectively collected.

Intervention: Major hepatectomy, defined as resection of two or more liver segments by Goldsmith and Woodburn nomenclature, was performed on all the patients. Main Outcome Measure: Hospital mortality, which was defined as death within the same hospital admission for the hepatectomy.

Results: Preoperative liver function in patients with cirrhosis was worse than in those with normal livers. The intraoperative blood loss was also higher (P=.01), but for patients with cirrhosis, chronic active hepatitis, and normal livers, the hospital mortality rates (13%, 16%, and 14%, respectively) were similar. The hospital mortality rate for patients with cirrhosis in the last 2 years of the study was only 5%. Patients with cirrhosis could tolerate up to 10 L of blood loss and survive the major hepatectomy. By discriminant analysis, an ICG retention of 14% at 15 minutes was cutoff level that could maximally separate the patients with cirrhosis with and without mortality.

Conclusion: Major hepatectomy for HCC in the presence of cirrhosis is associated with a mortality rate that is not different from the rate for patients with normal livers. An ICG retention of 14% at 15 minutes would serve as a better selection criterion than the 10% previously used.

Folate deficiency in rats induces DNA strand breaks and hypomethylation within the p53 tumor suppressor gene

Folate is essential for the de novo biosynthesis of purines and thymidylate, and is an important mediator in the transfer of methyl groups for DNA methylation. Folate deficiency, therefore, could contribute to abnormal DNA integrity and methylation patterns. We investigated the effect of isolated folate deficiency in rats on DNA methylation and DNA strand breaks both at the genomic level and within specific sequences of the p53 tumor suppressor gene. Our data indicate that folate deficiency induces DNA strand breaks and hypomethylation within the p53 gene. Such alterations either did not occur or were chronologically delayed when examined on a genome-wide basis, indicating some selectivity for the exons examined within the p53 gene. Folate insufficiency has been implicated in the development of several human and experimental cancers, and aberrations within these regions of the p53 gene that were examined in this study are thought to play an integral role in carcinogenesis. The aforementioned molecular alterations may therefore be a means by which dietary folate deficiency enhances carcinogenesis.

Overexpression of the 67 kD laminin receptor correlates with the progression of gastric carcinoma

This retrospective study was designed to investigate the relationship between overexpression of the 67 kD laminin receptor (67LR) using immunohistochemistry, and several clinicopathological parameters including overall survival in human gastric adenocarcinoma. We stained paraffin-embedded sections of 93 resected primary gastric adenocarcinomas using a polyclonal antibody specific for the 67LR as well as monoclonal antibodies for p53 protein, epidermal growth factor receptor, proliferating cell nuclear antigen, carcinoembryonic antigen and chromagranin. The results showed statistically significant correlations between overexpression of the 67LR and types of early or advanced gastric carcinoma (p < 0.001), depth of invasion (p < 0.001), WHO histopathologic classification (p < 0.001), stage (p = 0.001), expression of p53 protein (p = 0.019), expression of epidermal growth factor receptor (p < 0.001) and proliferating cell nuclear antigen labeling index (p = 0.002). A lower proportion of signet ring cells revealed a higher percentage of overexpression of 67LR in both early (p < 0.002) and advanced (p < 0.001) gastric carcinomas. Intestinal type adenocarcinoma (according to Lauren's classification) revealed a higher percentage of overexpression of the 67LR than the diffuse type in both early (p = 0.057) and advanced (p < 0.001) gastric carcinomas. The correlations between overexpression of the 67LR and lymph node metastasis were statistically significant (p < 0.07). Although the overexpression of the 67LR tended to correlate with lower survival rates, the correlation was not statistically significant due to the limited sample size. Our data revealed that overexpression of the 67LR is correlated with the progression of gastric carcinoma. The expression of the 67LR may be important as one of the steps which determines invasiveness during the progression of cancer.

Primary malignant lymphomas of the stomach. Pathological and clinical analyses of 38 resected cases

The stomach is the most frequent site of extranodal lymphoma and primary gastric lymphoma might be distinguished from the nodal lymphoma by its different pathogenesis and prognosis. Based on the Isaacson's classification, clinico-pathologic reviews of 38 resected primary gastric lymphomas were done. Immunohistochemical stainings for PCNA, B and T cell markers, bcl-2 and p53 were performed. Eighteen were of low grade and 20 were of high grade. There were significant differences between low and high graders in the aspect of the size, depth of lesion, gross type, immunophenotype, staining intensity for PCNA, expressions of bcl-2 and p53. The overall 2-year survival rate was 85.3%. Factors with prognostic significance on survival by univariate analyses included immunophenotype, histologic grading and PCNA staining pattern. After multivariate analyses, immunophenotype proved to be a significant factor. We think that the histologic grading by Isaacson's classification and the immunohistochemical stainings performed were useful in pathologic and/or clinical aspects. The excellent survival rate in this study was partly due to the selection of resectable cases. However, earlier diagnosis and appropriate treatment might have contributed to the improved prognosis of gastric lymphoma in recent years.

Dietary folate protects against the development of macroscopic colonic neoplasia in a dose responsive manner in rats

BACKGROUND AND AIMS

Diminished folate status is associated with enhanced colorectal carcinogenesis. This study investigated the potential chemopreventive role of dietary folate in the dimethylhydrazine colorectal cancer model.

SUBJECTS AND METHODS

Sprague-Dawley rats were fed diets containing either 0, 2 (daily dietary requirement), 8 or 40 mg folate/kg diet for 20 weeks. After five weeks of diet, rats were injected with dimethyl-hydrazine (44 mg/kg) weekly for 15 weeks. Fifteen weeks after the first injection of dimethylhydrazine, all rats were killed. Folate status was determined, and the entire colorectum from each rat was analysed for macroscopic and microscopic neoplasms.

RESULTS

Plasma and colonic folate concentrations correlated directly with dietary folate levels (p < 0.005). The incidence of microscopic neoplasms was similar among the four groups. However, the incidence and the average number of macroscopic tumours per rat decreased progressively with increasing dietary folate levels up to 8 mg/kg diet (p < 0.05). In the strongly procarcinogenic milieu used in this study, folate supplementation at 20 times the basal requirement was associated with rates of macroscopic tumour development that were intermediate, and not statistically distinct, from rates observed at either 0 or 8 mg/kg diet.

CONCLUSIONS

These data indicate that in this rat model, (a) increasing dietary folate up to four times the basal requirement leads to a progressive reduction in the evolution of macroscopic neoplasms from microscopic foci; and (b) folate supplementation beyond four times the requirement does not convey further benefit.

Blood pressure and HR in the fetal lamb: relationship to hypoglycemia, hypoxemia, and growth restriction

We examined blood pressure and heart rate (HR) in relation to glucose and arterial PO2 (PaO2) at approximately 121 days (early) and at approximately 140 days (late) gestation in 12 growth-restricted and 10 control fetal lambs. Mild growth restriction (relative to maternal weight) was produced by withdrawal of 25 ml/day of maternal blood during the second half of pregnancy (P < 0.05). Fetuses from this model are hypoglycemic during early and late gestation but hypoxemic only during late study. Mean systolic and diastolic pressures in the experimental group were approximately 8.0 mmHg lower than the corresponding values in controls at both studies (P < 0.05). Fetal HR (FHR) was 15.4 beats/min lower (P < 0.05) in 10 but was higher than control in 2 experimental fetuses that were also not growth restricted. There were significant correlations between late systolic pressure and HR and PaO2 (r = 0.54, P = 0.046 and r = 0.50, P = 0.049, respectively) and between FHR and blood pressure and birth weight/maternal weight (P < 0.05). We conclude that, in this model, fetal blood pressure and HR may serve as good indicators of hypoxemia and growth restriction.

Postoperative adjuvant arterial infusion chemotherapy for patients with hepatocellular carcinoma

BACKGROUND/AIMS

The efficacy of postoperative hepatic arterial infusion chemotherapy (PAI) in the prevention of the recurrence of hepatocellular carcinoma (HCC) following hepatic resections was examined.

MATERIAL AND METHODS

Between November 1982 and February 1994, hepatic resections were carried out in 74 consecutive HCC patients with stage III and IV at Oita Medical University Hospital. They were divided into two groups. In PAI group patients (n = 26), cis-diamminedichloroplatinum or a combination of 5-fluorouracil, adriamycin and mitomycin was alternately infused every 3 months. The remaining patients who did not receive PAI therapy served as the control (n = 48). The patient survival and disease-free survival of the two groups were compared.

RESULTS

The cumulative survival rates in the PAI group (90.3%, 71.3%, and 71.3% at 1, 2, and 3 years after hepatectomy, respectively) were significantly higher than those in the control (67.2, 41.7%, and 32.0%, respectively, p < 0.05). The disease-free survival rate in the PAI group (62.9%, 50.3%, and 26.8% at 1, 2, and 3 years after hepatectomy, respectively) was also significantly higher relative to the control (38.6%, 21.7%, and 12.1%, respectively, p < 0.01).

CONCLUSIONS

Our data indicate that PAI can be efficacious in preventing postoperative recurrence of carcinoma and may lead to a prolonged survival of advanced HCC patients following hepatic resection.

Exon-specific DNA hypomethylation of the p53 gene of rat colon induced by dimethylhydrazine. Modulation by dietary folate

Folate deficiency enhances colorectal carcinogenesis in dimethylhydrazine-treated rats. Folate is an important mediator of DNA methylation, an epigenetic modification of DNA that is known to be dysregulated in the early stages of colorectal cancer. This study investigated the effect of dimethylhydrazine on DNA methylation of the colonic p53 gene and the modulation of this effect by dietary folate. Sprague-Dawley rats were fed diets containing 0, 2, 8, or 40 mg of folate/kg of diet. Five weeks after diet initiation, dimethylhydrazine was injected weekly for fifteen weeks. Folate-depleted and folate-replete control animals did not receive dimethylhydrazine and were fed the 0- and 8-mg folate diets, respectively. The extent of p53 methylation was determined by a quantitative HpaII-polymerase chain reaction. In exons 6 and 7, significant p53 hypomethylation was observed in all dimethylhydrazine-treated rats relative to controls (P < 0.01), independent of dietary folate. In exon 8, significant p53 hypomethylation was observed only in the dimethylhydrazine-treated folate-depleted rats compared with controls (P = 0.038) and was effectively overcome by increasing levels of dietary folate (P = 0.008). In this model, dimethylhydrazine induces exon-specific p53 hypomethylation. In some exons, this occurs independent of dietary folate, and in others, increasing levels of dietary folate effectively override the induction of hypomethylation in a dose-responsive manner. This may be a mechanism by which increasing levels of dietary folate inhibit colorectal carcinogenesis.

Nutrition chemoprevention of gastrointestinal cancers: a critical review

Various strategies utilizing specific dietary factors have been investigated for their ability to modulate the development of several cancers of the gastrointestinal tract. The effects of fat, red meat, fiber, fruits and vegetables, and alcohol on colorectal carcinogenesis have been reasonably well defined. Folate, selenium, and omega-3 fatty acids are rapidly emerging as important agents in nutrition chemoprevention, while the role of antioxidant vitamins and calcium is less certain. Although recent intervention studies from China have suggested a protective role of certain vitamins and minerals for esophageal and gastric cancers, further data from prospective randomized intervention studies are needed. Until more firm data are available, the dietary recommendations provided by the American Cancer Society and the National Cancer Institute are appropriate guidelines.

Simple in situ hypothermia reduced ischaemic injury to human liver during hepatectomy

OBJECTIVE

To assess the preventive effect of simple in situ cooling on ischaemic injury in human livers.

DESIGN

Randomised study.

SETTING

University department of surgery, Japan.

SUBJECTS

20 patients who were to undergo liver resection (right lobectomy, n = 6, left lobectomy, n = 3, and posterior segmentectomy, n = 1, in each group); all but 2 who had normal remnant livers and were randomised to undergo either warm ischaemia or in situ cooling (n = 10 in each group).

INTERVENTIONS

Hypothermia was induced by rapid infusion of roughly 450 ml of cold Ringer's lactate into the portal vein during occlusion of the portal triad before resection.

MAIN OUTCOME MEASURES

Occlusion time, ATP concentrations, biochemical indicators of liver damage, and coagulation profile.

RESULTS

The mean (SD) occlusion time was 55 (6) minutes for the warm ischaemia group and 53 (3) for the in situ cooling group. After in situ cooling the state of the liver as indicated by serum alanine aminotransferase activity (ALT) and prothrombin time had improved substantially. Mean (SD) ALT activity was 516 (168) U/I in the warm ischaemia group compared with 305 (154) in the in situ cooling group (p < 0.02) on the first postoperative day. The respective figures for prothrombin time (%) were 56 (23) compared with 77 (14), (p < 0.05).

CONCLUSION

In situ cooling lessened the amount of ischaemic damage done to the liver during hepatectomy compared with treatment with warm ischaemia.

Can fish oil maintain Crohn's disease in remission?

One of the greatest challenges in managing Crohn's disease is to maintain remission. Although pharmacologic approaches to maintaining Crohn's disease in remission have significantly improved, most of the currently available modalities are associated with significant morbidity. Recently, an enteric-coated preparation of fish oil has been shown to be effective in reducing the rate of relapse in patients with Crohn's disease in remission who are at high risk of relapse. Because of minimal side effects, fish oil appears to be an ideal maintenance agent in Crohn's disease. However, until results from studies that compare the therapeutic effect of fish oil to the currently available maintenance agents are available, fish oil supplementation cannot be recommended as a sole maintenance agent at present. It does, however, seem prudent to promote a diet rich in fish oil in patients with Crohn's disease.

Nodal metastasis in the distal mesorectum: need for total mesorectal excision of rectal cancer

Locoregional failure of rectal cancer is a troublesome problem and a major cause of morbidity and mortality following curative surgery. The mesorectum has been regarded as an important site in local failure after surgery of rectal cancer. Total mesorectal excision (TME) has been raised by some colorectal surgeons to prevent early local recurrence. This study was performed to ascertain the incidence of metastatic lymph nodes in the distal mesorectum (DMR) of the colorectal cancer patient. We also examined the clinicopathologic risk factors of distal mesorectal metastasis. Eight of 53 patients had positive metastatic lymph nodes in DMR. Twenty-seven patients were Dukes B and 26 patients were Dukes C stage. Out of 26 Dukes C patients, 8 patients (30.8%) had metastatic lymph nodes in the DMR. However, there was no significant difference in risk factors between DMR positive and DMR negative patients with Dukes C stage. In conclusion, the incidence of metastatic lymph nodes in DMR was about 30.8%, therefore the mesorectum especially the DMR should be removed completely by total mesorectal excision to eradicate the metastatic lymph nodes which may cause local recurrence.

Effects of failure of the right side of the heart and increased pulmonary resistance on mechanical circulatory support with use of the miniaturized HIA-VAD displacement pump system

This experimental study was designed to assess the influence of failure of the right side of the heart or pulmonary hypertension, or both, on the performance of a novel miniaturized left ventricular assist device. In small-sized dogs (n = 50) ischemic global left ventricular failure was induced and support was provided by the HIA-VAD displacement pump (stroke volume 10 or 25 ml) installed as a left ventricular assist device. In three groups of animals (n = 10 each) pulmonary hypertension was created before induction of global left ventricular failure. During left ventricular assist device support temporary ischemic failure of the right side of the heart was induced in four groups of animals (n = 10 each). In the group subjected to left ventricular failure, support with the left ventricular assist device, and right ventricular failure during left ventricular assist, left atrial pressure and cardiac index were significantly lower than in the group subjected to left ventricular failure and left ventricular assist alone (2 +/- 6 versus 11 +/- 6 mm Hg and 1.6 +/- 0.4 versus 1.0 +/- 0.4 L/(min/m2), respectively, p < 0.05). In the group subjected to pulmonary hypertension, left ventricular failure, and left ventricular support, left atrial pressure dropped to values near zero but cardiac index remained unaltered as compared with results with the same regimen without pulmonary hypertension. However, when right ventricular failure was added (that is, pulmonary hypertension, left ventricular failure, left ventricular support, and right ventricular failure during support with the left ventricular assist device) left atrial pressure dropped to negative values (p < 0.05) and cardiac index progressively deteriorated. When, in an additional group of dogs, biventricular support was installed in the latter regimen, circulation was initially well supported but oxygenation deteriorated in 60% of cases. We conclude that (1) adequate right ventricular function was indispensable during support with the left ventricular assist device, (2) the combination of pulmonary hypertension and right ventricular failure led to the "low left ventricular assist device output syndrome," and (3) biventricular mechanical support in the presence of pulmonary hypertension may be complicated by the alveolar leakage syndrome.

DNA hypomethylation in inflammatory arthritis: reversal with methotrexate

This study investigated whether methotrexate, by interrupting the methyl transfer function of folate, can induce genomic DNA hypomethylation in patients with inflammatory arthritis. Consecutive subjects with inflammatory arthritis (rheumatoid or psoriatic), who were taking methotrexate (n = 7) or other medications (n = 6), and control subjects, either healthy or with osteoarthritis and taking nonsteroidal anti-inflammatory agents only (n = 9) were recruited. The methylation status of genomic DNA from peripheral blood mononuclear cells was determined. Plasma levels of folate, B12, and pyridoxal-5'-phosphate (PLP), all of which are involved in biologic methylation, were also examined. The extent of genomic DNA methylation was lowest in subjects with inflammatory arthritis who were not taking methotrexate, highest in subjects with inflammatory arthritis who were taking methotrexate, and intermediate in control subjects (p < 0.05). Plasma levels of folate and B12 were similar among the three groups. The mean plasma PLP level in subjects with inflammatory arthritis was 33% lower than that in control subjects (p = 0.04). No significant correlation between genomic DNA methylation and folate, B12, and PLP levels was observed. These data do not support the hypothesis that methotrexate induces genomic DNA hypomethylation. However, these data indicate that inflammatory arthritis is associated with genomic DNA hypomethylation that is reversed with methotrexate. Future studies using a larger number of subjects are warranted to confirm these findings.

Interaction of dibutyltin-3-hydroxyflavone bromide with the 16 kDa proteolipid indicates the disposition of proton translocation sites of the vacuolar ATPase

The organotin complex dibutyltin-3-hydroxyflavone bromide [Bu2Sn(of)Br] has been shown to bind to the 16 kDa proteolipid of Nephrops norvegicus, either in the form of the native protein or after heterologous expression in Saccharomyces and assembly into a hybrid vacuolar H(+)-ATPase. Titration of Bu2Sn(of)Br against the 16 kDa proteolipid results in a marked fluorescence enhancement, consistent with binding to a single affinity site on the protein. Vacuolar ATPase-dependent ATP hydrolysis was also inhibited by Bu2Sn(of)Br, with the inhibition constant correlating well with dissociation constants determined for binding of Bu2Sn(of)Br complex to the proteolipid. The fluorescence enhancement produced by interaction of probe with proteolipid can be back-titrated by dicyclohexylcarbodiimide (DCCD), which covalently modifies Glu140 on helix-4 of the polypeptide. Expression of a mutant proteolipid in which Glu140 was changed to a glycine resulted in assembly of a vacuolar ATPase which was inactive in proton pumping and which had reduced ATPase activity. Co-expression studies with this mutant and wild-type proteolipids suggest that proton pumping can only occur in a vacuolar ATPase containing exclusively wild-type proteolipid. The fluorescent enhancement of affinity of Bu2Sn(of)Br for the mutant proteolipid was not significantly altered, with the organotin complex having no effect on residual ATPase activity. Interaction of the probe with mutant proteolipid was unaffected by DCCD. These data suggest an overlap in the binding sites of organotin and DCCD, and have implications for the organization and structure of proton-translocating pathways in the facuolar H(+)-ATPase.

Ventricular premature beat-driven intermittent restoration of coronary blood flow reduces the incidence of reperfusion-induced ventricular fibrillation in a cat model of regional ischemia

With a cat model of regional cardiac ischemia, we examined whether the incidence of reperfusion-induced ventricular fibrillation (VF) could be reduced by ventricular premature beat (VPB)-driven intermittent reperfusion. In addition, we assessed whether the effect of the intermittent reperfusion was comparable with that of ischemic preconditioning in suppressing the VF. Of 15 cats subjected to uninterrupted reperfusion after 20-minute occlusion of the left anterior descending coronary artery, 13 (86.70%) had VF, whereas only 1 (7.1%) of 14 cats subjected to the VPB-driven intermittent reperfusion had VF. This incidence of VF was significantly lower than that of the animal group subjected to uninterrupted reperfusion. However, it was not statistically different from that (3 of 15) of the group subjected to a 10-minute episode of the coronary artery occlusion before the 20-minute occlusion (i.e., "ischermic preconditioning"). Our results suggest that the VPB-driven intermittent reperfusion (i.e., "postconditioning") is very effective in preventing reperfusion-induced VF and as good as, if not better than, ischemic preconditioning.