The dose-response effects of uric acid on the prevalence of metabolic syndrome and electrocardiographic left ventricular hypertrophy in healthy individuals.

BACKGROUND AND AIM: Hyperuricemia (HUA) is associated with the prevalence of metabolic syndrome (MetS) and cardiovascular risks in various populations. HUA is also able to induce cardiomyocyte hypertrophy in mouse models. However, the dose-response effects of serum uric acid (SUA) on the prevalence of MetS and electrocardiographic left ventricular hypertrophy (LVH) are unclear. METHODS AND RESULTS: We retrospectively collected data from 18,932 individuals who underwent an annual health examination between 1/1/2016 and 12/31/2016. We excluded those with systemic diseases or missing questionnaires. The primary study endpoints were the prevalence of MetS and LVH, which were defined by the criteria for the Taiwanese population and the "SPRINT" trial. The cohort consisted of 17,913 individuals with a mean age of 31.2 years (SD 7.4) and a mean body mass index of 24.6 kg/m2 (SD 3.6); 87.1% of the individuals were men. The prevalence rates of HUA, MetS, and LVH were 29.5%, 9.4%, and 0.32%, respectively, in the overall study population. The HUA group was predominantly male and had significantly poorer lifestyle choices and greater laboratory cardiometabolic biomarker values than did the normouricemic group. However, the frequencies of physical activity were comparable between the two groups. After adjusting for confounders, SUA was associated with MetS (OR:1.473, 95% CI:1.408-1.540, P < 0.001) and LVH (OR:1.301, 95% CI:1.064-1.591, P = 0.01). CONCLUSION: We demonstrated that the dose-response effects of SUA are associated with the prevalence of MetS and electrocardiographic LVH in healthy individuals from Taiwan. Based on this evidence, future studies should investigate urate-lowering therapy and cardiovascular benefits in individuals with HUA (ClinicalTrials.gov number NCT03473951).

Predictive value of nodal maximum standardized uptake value of pretreatment [18F]fluorodeoxyglucose positron emission tomography imaging in patients with esophageal cancer.

We retrospectively reviewed 102 patients with esophageal cancer (97.1% squamous cell carcinoma, 96.1% stage III) received FDG-PET staging and were treated by chemoradiotherapy with or without resection to assess whether the pretreatment [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) maximum standardized uptake value (SUVmax) of the primary tumor and metastatic lymph nodes can predict the prognosis of patients with esophageal cancer. Receiver operating characteristic analysis was performed to find the cutoff values for primary tumor SUVmax and nodal SUVmax. The influence of clinical factors including primary tumor SUVmax and nodal SUVmax on local progression-free survival, nodal progression-free survival (NPFS), distant metastases-free survival (DMFS), and overall survival (OS) were evaluated using univariate and multivariate analyses. A total of 40 patients received esophagectomy after neoadjuvant chemoradiotherapy (trimodality), while 62 patients received definitive chemoradiotherapy (dCRT). The median follow-up was 26.4 months. The SUVmax of primary tumor had no significant predictive value on all outcomes, while the SUVmax of metastatic lymph nodes had predictive value on several outcomes. High nodal SUVmax (≥7) predicted for worse outcomes than low nodal SUVmax (<7) in the patients who received dCRT (two-year DMFS, 17% vs. 92%, P < 0.001; NPFS, 14% vs. 81%, P = 0.001; OS, 21% vs. 50%, P = 0.003), but not in those received trimodality. On multivariate analysis of patients receiving dCRT, nodal SUVmax was the strongest independent predictor on DMFS (hazard ratio [HR] 13.93, P < 0.001), NPFS (HR 3.99, P = 0.026), PFS (HR 2.90, P = 0.003), and OS (HR 3.80, P = 0.001). High pretreatment nodal SUVmax predicts worse treatment outcomes for the patients treated with dCRT.

Characterization of residual tumours at the primary site in patients with a near pathological complete response after neoadjuvant chemoradiotherapy for oesophageal cancer.

BACKGROUND: A 'surgery as needed' strategy has been proposed for patients with oesophageal cancer who truly achieve a pathological complete response (pCR) following neoadjuvant chemoradiotherapy (nCRT). However, the ability to detect residual disease remains problematic. This study investigated the anatomical locations and pathological characteristics of residual cancer in patients with oesophageal squamous cell carcinoma (SCC) who achieved a near pCR following nCRT. METHODS: Patients with oesophageal SCC who achieved a near pCR after nCRT were eligible. Near pCR was defined as residual cancer in the resection specimen representing less than 10 per cent of the apparent original tumour area. RESULTS: Detailed histopathological reassessment of 76 consecutive patients (mean age 54·4 years) with a near pCR was undertaken. Some 32 patients (42 per cent) with a near pCR had no detectable mucosal lesions. Residual tumour was identified most frequently in the submucosal layer (54, 71 per cent), followed by the mucosa (44, 58 per cent), muscle layer (36, 47 per cent) and adventitia (22, 29 per cent) (P < 0·001). Among patients without ypT1a disease, increasing depth of tumour invasion correlated negatively with the likelihood of mucosal involvement. Of patients with ypT3 disease, 16 of 22 had no detectable cancer located in the mucosa, compared with six of 29 with ypT1b disease (P < 0·001). CONCLUSION: Better tools for predicting pCR are required before considering a 'surgery as needed' approach in the management of oesophageal cancer.

Association between the thoroughness of the histopathological examination and survival in patients with esophageal squamous cell carcinoma who achieve pathological complete response after chemoradiotherapy.

The College of American Pathologists guidelines recommend examining at least four representative tumor blocks for determining pathological T stage in patients with primarily resected esophageal cancer. Whether the same pathological requirements are adequate in patients undergoing esophagectomy following neoadjuvant chemoradiotherapy (nCRT) remains unclear. We hypothesized that current examination protocols may underestimate the presence of microscopical residual disease after nCRT, potentially leading to under-staging. We retrospectively reviewed the records of patients with esophageal squamous cancer (ESCC) who were diagnosed as having pathological complete response (pCR) following nCRT. The thoroughness of the pathological examination in pCR patients was examined using (i) the number of blocks examined in suspicious tumor area (≤4 vs. >4), and (ii) the block quotient (calculated as the pretreatment tumor length divided by the number of blocks examined in suspicious tumor area). A total of 91 patients were enrolled. The mean number of blocks used to confirm pCR was 4.8 (range: 2-14). The 5-year overall survival (OS) and disease-free survival (DFS) in the entire cohort were 55% and 65%, respectively. Multivariate analyses identified the block quotient as the only independent predictor of OS and DFS. Receiver operating characteristic curve analysis indicated an optimal cutoff value of 1.4 for the block quotient. Among the patients who achieved pCR, the 5-year DFS differed significantly between subjects with a low (≤1.4) or high (>1.4) block quotient (76% vs. 47%, respectively, P = 0.03). The block quotient (calculated by the pretreatment tumor length divided by the number of blocks) - which reflects the meticulousness of the histopathological examination for confirming pCR - is associated with survival in ESCC patients.

Anti-hepatitis C virus activity of 3-hydroxy caruilignan C from Swietenia macrophylla stems.

Chronic hepatitis C virus (HCV) infection ultimately leads to chronic hepatitis, hepatic cirrhosis and hepatocellular carcinoma (HCC). As the standard treatment is not completely efficacious, a safer and more effective agent against HCV infection needs to be developed. In this report, we demonstrated that 3-hydroxy caruilignan C (3-HCL-C) isolated from Swietenia macrophylla stems exhibited high anti-HCV activity at both protein and RNA levels at nontoxic concentrations, with an EC(50) value of 10.5 ± 1.2 µm. Combinations of 3-HCL-C and interferon-α (IFN-α), an HCV NS5B polymerase inhibitor (2'-C-methylcytidine; NM-107) or an HCV NS3/4A protease inhibitor (Telaprevir; VX-950) increased the suppression of HCV RNA replication. The results suggested that 3-HCL-C may be a potential anti-viral agent. We then demonstrated that 3-HCL-C interfered with HCV replication by inducing IFN-stimulated response element transcription and IFN-dependent anti-viral gene expression.

Long-term outcomes following neoadjuvant chemoradiotherapy in patients with clinical T2N0 esophageal squamous cell carcinoma.

The optimal treatment for patients with local esophageal cancer (cT2N0 disease) has not yet been defined. We sought to determine whether neoadjuvant chemoradiotherapy (CRT) can improve prognosis compared with direct esophagectomy in this patient group. Between 1994 and 2005, patients with cT2N0 esophageal squamous cell carcinoma who underwent either neoadjuvant CRT or surgery as first-line treatment were retrospectively reviewed. We collected information on their demographic characteristics, staging modality, clinical and pathological stages, perioperative course, and survival. The study endpoints included tumor recurrence, disease-specific survival (DSS), and overall survival rate. Of the 71 eligible patients, 14 received an esophagectomy first, whereas the remaining 57 received neoadjuvant CRT first. Despite the high pathological complete response (pCR) rate of 37% after neoadjuvant CRT, routine neoadjuvant CRT did not translate into better survival compared to direct surgery (5-year DSS: 39% vs. 68%, P= 0.17). The dramatic survival difference between pCR and non-pCR patients (5-year DSS: 85% vs. 4%, P < 0.001) accounts for these unsatisfactory results. In our series, the administration of neoadjuvant CRT to patients with clinical stage T2N0 esophageal squamous cell carcinoma did not significantly improve outcomes compared with direct esophagectomy.

San-Huang-Xie-Xin-Tang extract suppresses hepatitis C virus replication and virus-induced cyclooxygenase-2 expression.

Chronic hepatitis C virus (HCV) infection is associated with chronic inflammation of liver, which leads to the development of cirrhosis and hepatocellular carcinoma (HCC). Because of severe side effects and only a 50-70% cure rate in genotype 1 HCV-infected patients upon current standard treatment with pegylated interferon-α plus ribavirin, new therapeutic regimens are still needed. San-Huang-Xie-Xin-Tang (SHXT) is a transitional Chinese herbal formula, composed of Rhei rhizoma, Scutellaria radix and Coptidis rhizome, and possesses anti-inflammatory effect. Here, we describe a (+)-catechin-containing fraction extracted from SHXT, referred as SHXT-frC, exhibited effective inhibition of HCV replication, with selectivity index value (SI; CC50 /EC50) of 84, and displayed synergistic anti-HCV effects when combined with interferon-α, HCV protease inhibitor telaprevir or polymerase inhibitor 2'-C-methylcytidine. The activation of factor-κB (NF-κB) and cyclooxygenase-2 (COX-2) signalling pathway has particular relevance to HCV-associated HCC. SHXT-frC treatment also caused a concentration-dependent decrease in the induction of COX-2 and NF-κB expression caused by either HCV replication or HCV NS5A protein. Collectively, SHXT-frC could be an adjuvant treatment for patients with HCV-induced liver diseases.

Evaluation of cotton rats as a model for severe acute respiratory syndrome.

Experimental studies were conducted to evaluate two species of cotton rats, Sigmodon hispidus and Sigmodon fulviventer, as a model for severe acute respiratory syndrome (SARS). Blood and turbinate wash samples, and lung tissue were collected from each animal at different time points after SARS coronavirus (CoV) infection for determining the growth curve of virus, if any, by the standard infectivity assay in Vero E6 cells. In addition, sections of the lung, liver, spleen, and kidney were taken and used for histology analysis. All animals were observed daily for signs of illness, and in some experiments, animals were weighed on the day when they were sacrificed. The results indicated that the cotton rat species, S. hispidus and S. fulviventer, were not a useful model for either SARS-CoV infection or disease. This observation was supported by the absence of any signs of illness, the failure to consistently demonstrate virus in the blood and tissues, and the absent of any notable histopathology. However, infected animals were capable of producing neutralizing antibodies against SARS-CoV, suggesting the seroconversion did occur. Further studies are warranted to consider other animal species in efforts to find better animal models for the evaluation of SARS-CoV vaccines and antiviral drugs.

Evaluation of readmission in children receiving allogeneic hematopoietic stem cell transplantation: an institutional experience.

BACKGROUND: Use of unrelated cord blood (UCB) has become increasingly popular as a stem cell source, given the rapid availability and decreased potential of graft-versus-host disease. We sought to ascertain whether the use of UCB transplantation for pediatric patients changed the rates of unscheduled readmission. METHODS: We analyzed the rate, causes, and evolution of hospitalization among patients receiving UCB versus matched sibling bone marrow. A retrospective analysis of the data from 54 patients who received a matched sibling hematopoietic stem cell transplantation (HSCT; n = 25; 46.3%) versus an unrelated cord blood transplantation (CBT; n = 29; 53.7%) was performed on subjects treated between 1998 and 2006. Patients who died before discharge (n = 4) were excluded from the readmission analysis. RESULTS: A total of 50 patients were recruited for the analyses. Their median age was 6.7 years (range = 0.2-17 years). The median duration of hospitalization was 18 days shorter in the sibling HSCT group than in the unrelated CBT group. There were 89 readmissions in 25 patients (50%): 49 readmissions (55%) in the related HSCT and 40 (45%) in the unrelated CBT cohorts. Forty-two percent of readmissions were due to infections. Mortality following transplantation in 10 patients (19%) included sepsis (n = 3), intracranial hemorrhage (n = 1), pulmonary hemorrhage (n =1), and relapse (n = 5). Seven patients received HSCT from HLA-identical sibling donors and three from a cord blood donor. CONCLUSION: For both groups, infection was the most common reason for readmission followed by graft failure and extramedullary relapse. Although the median hospital stay was shorter in the sibling donor group, some uncertainty exists as to whether the increased risk for readmission was related to proportionally more malignancies or to the severity of the illness. After HSCT, there was a frequent use of hospital resources: 46% of patients were hospitalized for a median of 11 days. The resulting health expenses seem to be useful, since 81% of subjects survived at 36-month follow-up.

Perineural invasion through the sheath in posttherapy esophagectomy specimens predicts poor survival in patients with esophageal squamous cell carcinoma.

BACKGROUND: The prognostic impact of perineural invasion (PNI) in patients with esophageal cancer who receive neoadjuvant chemoradiotherapy (nCRT) remains unclear. METHODS: A thorough pathological review of PNI was performed on post-nCRT esophagectomy specimens obtained from non-ypT0 patients with esophageal squamous cell carcinoma (ESCC). When PNI was identified, it was classified according to the presence or absence of penetration through the nerve sheath (i.e., PNI surrounding the nerve sheath [PNI-SS] versus PNI penetrating through the nerve sheath [PNI-TS]). The impact of PNI on overall survival (OS) was assessed in combination with clinical and pathological risk factors. RESULTS: A total of 177 eligible patients were identified between 1998 and 2008. PNI was identified in 43.5% (77/177) of participants. Of them, 33 and 44 had PNI-SS and PNI-TS, respectively. The 5-year OS rate of patients with PNI-TS was significantly lower (6.7%) than that observed in those without PNI (30.6%, P < 0.001). However, the 5-year OS observed in the latter group did not differ significantly from that of patients with PNI-SS (26%, P = 0.68). Multivariate analysis identified PNI-TS (hazard ratio [HR] = 1.965, P = 0.02), LVI (HR = 1.514, P = 0.048), and ypN2 stage (HR = 2.39, P = 0.007) as independent adverse prognostic factors for OS. CONCLUSIONS: The presence of PNI-TS after nCRT is associated with poor survival. A thorough assessment of distinct PNI patterns (i.e., PNI-TS versus PNI-SS) should be part of the routine post-nCRT histopathological work-up of ESCC patients.

Prognosis of patients with esophageal squamous cell carcinoma who achieve major histopathological response after neoadjuvant chemoradiotherapy.

BACKGROUND: The purpose of this study was to investigate the prognosis and its predictors in patients with esophageal squamous cell carcinoma (ESCC) who achieve major histopathological response (MaHR) after neoadjuvant chemoradiotherapy (nCRT). METHODS: We examined a total of 187 ESCC patients who achieved MaHR following nCRT and survived the perioperative period. MaHR was defined as either absence or <10% vital residual tumor cells (VRTC) in the resected esophagus without nodal involvement. Univariate and multivariate analyses were used to identify factors significantly associated with overall survival (OS). RESULTS: At the time of analysis, 113 patients (60.4%) were dead (5-year OS = 48%; median survival time = 54.8 months). The amount of VRTC (1-10% versus 0% VRTC; hazard ratio [HR] = 1.9, P < 0.001) and the thoroughness of histopathological examination (standard [≤ 4 tumor blocks] versus thorough [> 4 tumor blocks], HR = 1.57; P = 0.013) were independent predictors of OS in multivariate analysis. A stepwise increase in OS was observed in the following groups: patients with 1-10% VRTC identified by the standard protocol, patients with 1-10% VRTC identified by the thorough protocol, patients with 0% VRTC identified by the standard protocol, and patients with 0% VRTC identified by the thorough protocol (5-year OS rates = 20%, 40%, 50%, and 62%, respectively, P < 0.001). CONCLUSIONS: In ESCC patients who achieve MaHR after nCRT, the presence of microscopical residual disease and the thoroughness of histopathological examination are associated with survival.

An improved method for isolation of photosystem II from marine alga Porphyra yezoensis Udea.

An improved method for isolation and characterization of photosystem (PS)II particles from thylakoid membranes of gametophytes of a marine alga Porphyra yezoensis Udea is reported. Thylakoid membranes were isolated using ultracentrifugation and differential speeds centrifugation and were further purified by the first sucrose density gradient centrifugation (SDGC). PSII particles with high 2, 6-dichloroindophenol (DCIP) photo-reduction activity were isolated by the second SDGC from the thylakoid membranes. Absorption and fluorescence spectra of the thylakoid membranes and PSII particles were recorded and their polypeptides composition was studied. Thylakoid membranes obtained by the above two methods showed similar spectral properties and polypeptides composition. PSII particles, in addition to common extrinsic proteins found in PSII of other plants, contained cyt c-550, a 20 kDa protein, along with two new proteins (14 kDa and 16 kDa).

Synthesis and biological activity of unsaturated carboacyclic purine nucleoside analogues.

Two new carboacyclic nucleoside analogues, 9-[4-hydroxy-3-(hydroxymethyl)-2-butenyl]adenine (6) and 9-[4-hydroxy-3-(hydroxymethyl)-2-butenyl]guanine (5), modeled on the unsaturated carbocyclic nucleoside analogue neplanocin A (2), have been synthesized and tested for antiviral activity against HSV-2 and, in the case of 6, for activity against influenza and in vitro inhibition of S-adenosylhomocysteine hydrolase. The synthesis was accomplished through the coupling of either adenine or the guanine precursor 2-amino-6-chloropurine (15) to the key intermediate 1-(benzyloxy)-2-[(benzyloxy)methyl]-4-chloro-2-butene (13). Debenzylation of the N-9 adenine adduct gave 6 directly, while the product of the debenzylation of the N-9 adduct of 15 when treated with sodium hydroxide gave the guanine analogue 5. The carboacyclic guanine analogue (5) exhibited significant antiviral activity against HSV-2 (VR = 1.5, MIC50 = 65.6 micrograms/mL), a level of activity that is superior to that of ara-A but inferior to that of acyclovir. The adenine analogue 6 was active against HSV-2 only at a very high dose; it was devoid of antiviral activity against influenza type A2, and it lacked inhibitory activity against S-adenosylhomocysteine hydrolase.

A ring-enlarged oxetanocin A analogue as an inhibitor of HIV infectivity.

Two ring-expanded analogues (compounds 2 and 3) of the anti-HIV fermentation product oxetanocin A (1) were synthesized from commercially available diacetone D-glucose. Antiviral testing against HIV in ATH8 cells revealed that the ring-expanded analogue 2 possessed a similar activity profile as oxetanocin A. Neither compound, however, was capable of providing full protection to the cells against HIV infection. The isomeric ring-expanded analogue 3 was totally devoid of anti-HIV activity. Molecular modeling suggested that while oxetanocin A and compounds 2 and 3 share a large common substructure with the potent anti-HIV drug, dideoxyadenosine (ddA), the extra hydroxymethyl substituent may contribute negatively to the binding of these molecules to a critical enzyme. The negative contribution may be less important in oxetanocin and isomer 2 than in isomer 3. From these studies it would appear that both oxetane and tetrahydrofuran rings are equivalent templates to support the adenine base in terms of anti-HIV activity.

Synthesis of 3-deazaneplanocin A, a powerful inhibitor of S-adenosylhomocysteine hydrolase with potent and selective in vitro and in vivo antiviral activities.

The neplanocin A analogue 3-deazaneplanocin A (2b) has been synthesized. A direct SN2 displacement on the cyclopentenyl mesylate 3 by the sodium salt of 6-chloro-3-deazapurine afforded the desired regioisomer 4 as the major product. After deprotection, this material was converted to 3-deazaneplanocin A in two steps. X-ray crystallographic analysis confirmed the assigned structure. Consistent with its potent inhibition of S-adenosylhomocysteine hydrolase, 3-deazaneplanocin A displayed excellent antiviral activity in cell culture against vesicular stomatitis, parainfluenza type 3, yellow fever, and vaccinia viruses. Antiviral activity was also displayed in vivo against vaccinia virus by using a mouse tailpox assay. The significantly lower cytotoxicity of 3-deazaneplanocin A, relative to its parent compound neplanocin A, may be due to its lack of conversion to 5'-triphosphate and S-adenosylmethionine metabolites.

Acid-stable 2'-fluoro purine dideoxynucleosides as active agents against HIV.

2',3'-Dideoxy purine nucleosides have anti-HIV activity in vitro and the inosine analogue is being clinically evaluated. The instability of these compounds toward acidic conditions complicates oral administration. The effect of the addition of a fluorine atom to the 2'-position was investigated by preparing the fluorine-containing 2'-erythro and 2'-threo isomers of ddA and the threo isomer of ddI. All fluorine-containing compounds were indefinitely stable to acidic conditions which completely decomposed ddI (1) and ddA (2) in minutes. While the fluorine-containing erythro isomer, 5, was inactive, the threo isomers, 2'-F-dd-ara-A (3) and 2'-F-dd-ara-I (4), were just as potent and active in protecting CD4+ ATH8 cells from the cytopathogenic effects of HIV-1 as the parent drugs. Exposure to pH 1 at 37 degrees C prior to testing destroyed the activity of ddA and ddI but left the anti-HIV properties of 3 and 4 unchanged. The fluorinated analogues also protected cells exposed to HIV-2 and inhibited gag gene product expression but not as effectively as the parent compounds. The fluorine-containing analogues appear to be somewhat more toxic in vitro to the antigen- and mitogen-driven proliferation of immunocompetent cells than their corresponding parent compounds.

Thiazole-4-carboxamide adenine dinucleotide (TAD). Analogues stable to phosphodiesterase hydrolysis.

Thiazole-4-carboxamide adenine dinucleotide (TAD), the active metabolite of the oncolytic C-nucleoside tiazofurin (TR), is susceptible to phosphodiesteratic breakdown by a unique phosphodiesterase present at high levels in TR-resistant tumors. Since accumulation of TAD, as regulated by its synthetic and degradative enzymes, appears to be an important determinant for sensitivity to the drug, a series of hydrolytically resistant phosphonate analogues of TAD were synthesized with the intent of producing more stable compounds with an ability to inhibit IMP dehydrogenase equivalent to TAD itself. Isosteric phosphonic acid analogues of TR and adenosine nucleotides were coupled with activated forms of AMP and TR monophosphate to give dinucleotides 2 and 4. Coupling of protected adenosine 5'-(alpha, beta-methylene)diphosphate with isopropylidene-TR in the presence of DCC afforded compound 3 after deprotection. These compounds are more resistant than TAD toward hydrolysis and still retain potent activity against IMP dehydrogenase in vitro. beta-Methylene-TAD (3), the most stable of the TAD phosphonate analogues, produced a depletion of guanine nucleotide pools in an experimentally induced TR-resistant P388 tumor variant that was superior to that obtained with TR in the corresponding sensitive line.

Defective infection of rabbit peripheral blood monocyte cultures with human immunodeficiency virus type 1.

Human immunodeficiency virus type 1 (HIV-1) produces abortive infections of primary cultures of rabbit peripheral blood mononuclear cells (PMBCs). Mitogen activation of rabbit PBMCs or the addition of exogenous cytokines to the cultures does not change the level of release of the early HIV core protein, p24, into the culture medium. The amount of p24 increases steadily and reaches peak levels about 7 days after infection. HIV-1-specific DNA env sequences are also detected in infected PBMCs. However, reverse transcription of RNA of samples from activated infected cultures to cDNA, followed by amplification by the polymerase chain reaction, revealed transcription of gag, but not env, regions, suggesting that HIV-1 infection of rabbit PBMC does not lead to the replication and maturation of complete HIV-1 virions. In addition, neither CPE nor lytic infection was observed in HIV-1-infected rabbit cells and infectivity could not be transferred from rabbit cells infected with HIV for up to 2 weeks to MT-2 or H9 indicator cell lines. In addition, no CPE was seen in long-term cultures of the HTLV-I-transformed rabbit cell line PLT-1441, after inoculation with HIV. It is concluded that primary rabbit PBMCs may be infectable by HIV-1 but are not permissive for production of infectious virus. This conclusion is consistent with the apparent long-term latent infection seen after inoculation of rabbits with HIV-1 or HIV-1-infected cells.

Locally recurrent nasopharyngeal carcinoma.

PURPOSE: To assess the outcome of and determine prognostic factors for locally recurrent nasopharyngeal carcinoma (NPC) in patients treated with a second course of radiotherapy (RT). MATERIALS AND METHODS: From 1982 to 1995, 186 NPC patients, who had initially been treated in the Department of Radiation Oncology, Chang Gung Memorial Hospital-Linkou, developed local recurrence in the nasopharynx and were re-treated with RT (>/=20 Gy). The time from the initial RT to re-treatment ranged from 8 to 136 months (median: 23 months). All patients were treated with external RT and conformal radiotherapy was used in 35 patients after 1993. Fifteen received radiosurgery as a boost treatment. The RT dose at the nasopharyngeal tumor area ranged from 20 to 67.2 Gy (median 50 Gy). Eighty-two patients received one to eight courses of cisplatin-based chemotherapy in addition to RT. RESULTS: The 1-, 3- and 5-year survival was 54.9, 22. 1 and 12.4%, respectively. Patients whose tumor relapsed later than 2 years after the first treatment had a better survival than those with earlier relapse (3-year survival: 30.1 vs. 10.8%; P=0.015), but the difference became insignificant in patients who received >/=50 Gy. Patients without evidence of intracranial invasion or cranial nerve palsy had better survival than those with such lesions (3-year survival: 30.9 vs. 3.7%; P=0.006). A re-treatment dose >/=50 Gy yielded better survival (3-year survival: 22.8 vs. 18.5%; P=0.003). Addition use of radiosurgery may improve survival. The use of chemotherapy did not improve survival. Conformal radiotherapy resulted in significantly fewer severe complications than conventional RT. CONCLUSIONS: A repeat course of RT for locally recurrent NPC successfully prolongs survival in a significant number of patients. Intracranial invasion and/or cranial nerve palsy and re-treatment dose affect the prognosis, with a dose of >/=50 Gy significantly improving survival. Radiosurgery boost may also improve survival. Our preliminary data indicates that conformal radiotherapy may decrease the severity of radiation-induced complications. However; longer follow-up and larger sample size is necessary to document the findings.

3-Deazaneplanocin A: a new inhibitor of S-adenosylhomocysteine synthesis and its effects in human colon carcinoma cells.

The mechanism of action of the cyclopentenyl analogue of 3-deazaadenosine (3-deazaneplanocin A or c3Nep) was investigated in the human colon carcinoma cell line HT-29. Upon exposure of cells for 24 hr to 3-deazaneplanocin A (c3Nep), neplanocin A (Nep) or 3-deazaaristeromycin (c3Ari), significant toxicity was noted only for Nep, wherein an 87% reduction in viability was produced at a 100 microM concentration. c3Nep and c3Ari at 100 microM reduced viability by 34 and 21%, respectively. Intracellular levels of S-adenosylhomocysteine (AdoHcy) were elevated by a 24-hr exposure to 100 microM c3Nep, Nep and c3Ari and were 120, 75 and 25 pmoles/10(6) cells respectively. Only Nep was metabolized to an S-adenosylmethionine-like metabolite, and its formation was dose-related to its cytotoxicity. The t1/2 for the disappearance of elevated levels of AdoHcy following drug removal was 1.6 to 2.5 hr for all drugs. rRNA and tRNA methylation was inhibited significantly by Nep, but c3Nep and c3Ari inhibited tRNA methylation but not rRNA methylation to a lesser degree. These results demonstrate that c3Nep is a potent inhibitor of AdoHcy synthesis with a low degree of cytotoxicity.