Cardiac autonomic function and insulin resistance for the development of hypertension: a six-year epidemiological follow-up study.

BACKGROUND AND AIMS: To explore the impact of cardiac autonomic function (CAF) and insulin resistance (IR) on incident hypertension. METHODS AND RESULTS: In 1996, 1638 subjects finished baseline examination, which included anthropometry, blood pressures, CAF, blood biochemistry, plasma insulin, urine examination and electrocardiogram. CAF included standard deviation of normal-to-normal intervals or RR intervals (SDNN), low- and high-frequency power spectrum (LF and HF), and LF/HF ratio at supine for 5 min, the RR interval changes during lying-to-standing maneuver, and the ratio between the longest RR interval during expiration and the shortest RR interval during inspiration (E/I ratio). We used homeostasis model assessment to define beta cell function (HOMA-B) and insulin resistance (HOMA-IR). In total, 992 non-hypertensive participants completed the follow-up assessment in 2003 and 959 participants were included for the final analysis. Incident hypertension was determined by blood pressure status at follow-up. In unadjusted model, both square root of HOMA-IR (OR:3.37, 95%CI: 2.10-6.64) and HOMA-B (OR:0.996, 95%CI: 0.992-0.999) were related to incident hypertension. In multivariate model, square root of HOMA-IR (OR:1.97, 95%CI: 1.05-3.70), but not HOMA-B, was associated with incident hypertension. After further adjustment for baseline CAF, the positive relationship between the square root of HOMA-IR and incident hypertension disappeared. In contrast, LF/HF ratio (OR:1.18, 95%CI: 1.01-1.37), HF power (OR:0.98, 95%CI: 0.96-0.999), and E/I ratio (OR:0.71, 95%CI: 0.54-0.95) were each independently associated with incident hypertension after further adjustment for HOMA measures. CONCLUSION: Sympathovagal imbalance with an apparently decreased parasympathetic tone is an important predictor of incident hypertension independent of IR.

Characteristics of polycyclic aromatic hydrocarbon emissions of particles of various sizes from smoldering incense.

Release of polycyclic aromatic hydrocarbons (PAHs) in particles of various sizes from smoldering incenses was determined. Among the three types of incense investigated, yielding the total PAH emission rate and factor ranges for PM0.25 were 2,139.7-6,595.6 ng/h and 1,762.2-8,094.9 ng/g, respectively. The PM0.25/PM2.5 ratio of total PAH emission factors and rates from smoldering three incenses was greater than 0.92. This study shows that total particle PAH emission rates and factors were mainly <0.25 µm. Furthermore, the total toxic equivalency emission rates and factors of PAHs for PM0.25 were 241.3-469.7 and 198.8-576.2 ng/g from the three smoldering incenses. The benzo[a]pyrene accounted for 65.2%-68.0% of the total toxic equivalency emission factor of PM2.5 for the three incenses. Experimental results clearly indicate that the PAH emission rates and factors were influenced significantly by incense composition, including carbon and hydrogen content. The study concludes that smoldering incense with low atomic hydrogen/carbon ratios minimized the production of total polycyclic aromatic hydrocarbons of both PM2.5 and PM0.25.

Seasonal variation and health risk assessment of polycyclic aromatic hydrocarbons in Miaoli city, Taiwan.

The ambient PAHs levels in the downtown area of a traditional small city were analyzed for winter and summer seasons. A total of 16 PAHs in gaseous and particulate phase were quantified. The average gaseous PAHs were 2,189 ± 1,194 and 623.8 ± 545.1 ng/m(3) in winter and summer seasons, respectively. For the PAHs in particulate phase, they were 40.32 ± 12.15 and 11.99 ± 5.63 ng/m(3) in winter and summer seasons, respectively. These values were comparable to those reported for large cities or even higher. The estimated BaPeq was 12.32 ± 6.34 ng/m(3). As low-molecular-weight PAHs primarily existed in gaseous phase, high-molecular-weight PAHs in particulate phase became a significant fraction of total particulate phase PAHs. Particulate phase PAHs was significantly inversely associated with the ambient temperature for each individual PAHs species. However, this relationship did not exist for high-molecular-weight PAHs in gaseous phase. The results indicated the photo-degradation of high-molecular-weight PAHs should warrant a further thoughtfully investigation.

Evaluation of miR-429 as a novel serum biomarker for pancreatic ductal adenocarcinoma and analysis its tumor suppressor function and target genes.

OBJECTIVE: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal types of cancer. Various microRNAs have been identified to play an important role in PDAC. The study aimed to explore the role of miR-429 in PDAC. PATIENTS AND METHODS: The expression and prognostic value of miR-429 were first analyzed using The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Next, miR-429 expression was evaluated in the tissues and serum of 90 patients with PDAC. CCK8, SRB, wound healing and transwell assays were used to determine the effect of miR-429 on the proliferation, invasion, and migration of PDAC cells, respectively. Weighted gene co-expression network analysis (WGCNA), correlation analysis, TargetScan, and miRDB databases were used to screen and identify the target genes of miR-429. RESULTS: The results revealed that the expression of miR-429 was downregulated in PDAC tissues and the serum compared with those in normal tissues and the serum of healthy volunteers, respectively. The decreased expression of miR-429 was significantly associated with shorter overall survival. The overexpression of miR-429 significantly inhibited the proliferation, invasion, and migration of PDAC cells. Potential target genes of miR-429 were identified using WGCNA and bioinformatics analysis, and the results showed that cadherin 11 (CDH11), inositol polyphosphate-4-phosphatase type I (INPP4A), laminin gamma 1 (LAMC1), low density lipoprotein receptor-related protein 1 (LRP1), and quaking (QKI) were potential target genes of miR-429 in PDAC. Lower expression of CDH11 and QKI was associated with a more favorable prognosis in patients with PDAC. The overexpression of miR-429 could inhibit the expression of CDH11 and QKI. A nomogram model, involving miR-429, CDH11, and QKI, was subsequently constructed to determine their ability to accurately predict overall and disease-free survival in patients with PDAC. CONCLUSIONS: Taken together, miR-429 is involved in the development and progress of PDAC. MiR-429 could be recommended as a prognostic biomarker and therapeutic indicator in PDAC diagnosis.

Nitric oxide localized to spinal cords of mice with experimental allergic encephalomyelitis: an electron paramagnetic resonance study.

Experimental allergic encephalomyelitis (EAE) is a demyelinating autoimmune disorder that can be induced in susceptible mice by T lymphocytes sensitized to central nervous system (CNS) myelin components and is a prime animal model for the human CNS demyelinating disorder, multiple sclerosis (MS). Although CNS inflammation in which T lymphocytes and activated macrophages are the predominant cell types is observed in mice with EAE and in humans with MS, the exact mechanisms underlying the CNS damage and demyelination are not understood. Nitric oxide (NO), a gaseous free radical, has recently been shown to be a cytolytic product of activated macrophages. Using electron paramagnetic resonance spectroscopy, the nitric oxide free radical complexed with iron-sulfur proteins has been identified in affected spinal cords of mice with EAE, concurrent with the diminution of iron-sulfur proteins. These results indicate NO may play a role in the disease process of EAE, and perhaps MS.

Modulation of in vivo alloreactivity by inhibition of inducible nitric oxide synthase.

The role of nitric oxide in the immune response to allogeneic tissue was explored in an in vivo cardiac transplant model in the rat. Nitric oxide production during organ rejection was demonstrated by elevations in systemic serum nitrite/nitrate levels and by electron paramagnetic resonance spectroscopy. Messenger RNA for the inducible nitric oxide synthase enzyme was detected in the rejecting allografted heart, but not in the nonrejecting isografted heart. The enzyme was demonstrated to be biologically active by the in vitro conversion of L-arginine to L-citrulline and was immunohistochemically localized to the infiltrating inflammatory cells. Treatment with aminoguanidine, a preferential inhibitor of the inducible nitric oxide synthase isoform, prevented the increased nitric oxide production in the transplanted organ and significantly attenuated the pathogenesis of acute rejection. Aminoguanidine treatment prolonged graft survival, improved graft contractile function, and significantly reduced the histologic grade of rejection. These results suggest an important role for nitric oxide in mediating the immune response to allogeneic tissue. Inhibition of inducible nitric oxide synthase may provide a novel therapeutic modality in the management of acute transplant rejection and of other immune-mediated processes.

Vascular stents in the management of portal venous complications in living donor liver transplantation.

To evaluate the efficacy of stent placement in the treatment of portal vein (PV) stenosis or occlusion in living donor liver transplant (LDLT) recipients, 468 LDLT records were reviewed. Sixteen (10 PV occlusions and 6 stenoses) recipients (age range, 8 months-59 years) were referred for possible interventional angioplasty (dilatation and/or stent) procedures. Stent placement was attempted in all. The approaches used were percutaneous transhepatic (n = 10), percutaneous transsplenic (n = 4), and intraoperative (n = 2). Technical success was achieved in 11 of 16 patients (68.8%). The sizes of the stents used varied from 7 mm to 10 mm in diameter. In the five unsuccessful patients, long-term complete occlusion of the PV with cavernous transformation precluded catherterization. The mean follow-up was 12 months (range, 3-24). The PV stent patency rate was 90.9% (10/11). Rethrombosis and occlusion of the stent and PV occurred in a single recipient who had a cryoperserved vascular graft to reconstruct the PV during the LDLT operation. PV occlusion of >1 year with cavernous transformation seemed to be a factor causing technical failure. In conclusion, early treatment of PV stenosis and occlusion by stenting is an effective treatment in LDLT. Percutaneous transhepatic and transsplenic, and intraoperative techniques are effective approaches depending on the situation.

Serious pulmonary toxicity in patients with Hodgkin's lymphoma with SGN-30, gemcitabine, vinorelbine, and liposomal doxorubicin is associated with an FcγRIIIa-158 V/F polymorphism.

BACKGROUND: Based on in vitro synergistic cytotoxicity when anti-CD30 antibodies are combined with gemcitabine, the Cancer and Leukemia Group B conducted a double-blind, randomized, phase II trial of SGN-30 with gemcitabine, vinorelbine, and pegylated liposomal doxorubicin (GVD) in patients with relapsed Hodgkin's lymphoma. PATIENTS AND METHODS: In part 1 of the trial, 16 patients received SGN-30 with GVD to assess the safety of the combination. In part 2, patients were randomly allocated to SGN-30 (n = 7) or placebo (n = 7) with GVD to determine overall response rate (ORR). RESULTS: ORR in all 30 patients was 63% (65% with SGN-30 plus GVD, n = 23, and 57% with placebo plus GVD, n = 7). Median event-free survival was 9.0 months, with no difference between the two arms. Grades 3-5 pneumonitis occurred in five patients receiving SGN-30 and GVD, leading to premature closure of the trial. All five patients with pulmonary toxicity had a V/F polymorphism in the FcγRIIIa gene (P = 0.008). CONCLUSIONS: Together with historical data demonstrating a 2% incidence of pulmonary events with GVD, these results indicate that SGN-30 cannot safely be administered concurrently. The risk of pneumonitis with SGN-30 and GVD is greatest in patients with an FcγRIIIa V/F polymorphism.

A retrospective study of catastrophic invasive fungal infections in patients with systemic lupus erythematosus from southern Taiwan.

As very few large scale publications of invasive fungal infection (IFI) have been reported in lupus patients from individual medical centers, a retrospective study was performed from 1988 to 2009 in southern Taiwan. Demographic characteristics, clinical and laboratory data, and mycological examinations were analyzed. Twenty cases with IFI were identified in 2397 patients (0.83% incidence). There were 19 females and one male with an average age of 31.8 +/- 12.6. Involved sites included eight disseminated cases, six central nervous system, four lungs, one abdomen and one soft tissue. IFI contributed to a high mortality with 10 deaths (50%), and there were no survivors for the disseminated cases and Candida-infected patients. High activity (Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) > 8) was noted in 50% of IFI episodes. The survival from IFI diagnosis to death was only 7.7 +/- 4.2 days, all in a rapid course. No statistical difference was found between survivors and non-survivors when comparing their SLEDAI. Eighty-five percent of IFI episodes under high dosages of corticosteroids therapy and 95% of patients had lupus nephritis. There was an increased risk of IFI in the lupus patients receiving high daily dosage of prednisolone therapy. Critical information from analyses of the present large series could be applied into clinical practices to reduce the morbidity and mortality in such patients.

Liver graft regeneration in right lobe adult living donor liver transplantation.

Optimal portal flow is one of the essentials in adequate liver function, graft regeneration and outcome of the graft after right lobe adult living donor liver transplantation (ALDLT). The relations among factors that cause sufficient liver graft regeneration are still unclear. The aim of this study is to evaluate the potential predisposing factors that encourage liver graft regeneration after ALDLT. The study population consisted of right lobe ALDLT recipients from Chang Gung Memorial Hospital-Kaohsiung Medical Center, Taiwan. The records, preoperative images, postoperative Doppler ultrasound evaluation and computed tomography studies performed 6 months after transplant were reviewed. The volume of the graft 6 months after transplant divided by the standard liver volume was calculated as the regeneration ratio. The predisposing risk factors were compiled from statistical analyses and included age, recipient body weight, native liver disease, spleen size before transplant, patency of the hepatic venous graft, graft weight-to-recipient weight ratio (GRWR), posttransplant portal flow, vascular and biliary complications and rejection. One hundred forty-five recipients were enrolled in this study. The liver graft regeneration ratio was 91.2 +/- 12.6% (range, 58-151). The size of the spleen (p = 0.00015), total portal flow and GRWR (p = 0.005) were linearly correlated with the regeneration rate. Patency of the hepatic venous tributary reconstructed was positively correlated to graft regeneration and was statistically significant (p = 0.017). Splenic artery ligation was advantageous to promote liver regeneration in specific cases but splenectomy did not show any positive advantage. Spleen size is a major factor contributing to portal flow and may directly trigger regeneration after transplant. Control of sufficient portal flow and adequate hepatic outflow are important factors in graft regeneration.

Alemtuzumab (Campath-1H) in the treatment of chronic lymphocytic leukemia.

Alemtuzumab (Campath-1H) is a humanized IgG1 monoclonal antibody that targets the human CD52 antigen. CD52 is expressed by a variety of lymphoid neoplasms and most human mononuclear cell subsets. In 2001, alemtuzumab was approved for marketing in the United States and Europe for use in patients with fludarabine-refractory chronic lymphocytic leukemia (CLL). In heavily pretreated patients with CLL, the overall response rate (ORR) is approximately 35%, and in previously untreated patients the ORR is greater than 80%, with a recent randomized study suggesting it is superior to alkylator-based therapy. Importantly, alemtuzumab is effective in patients with high-risk del(17p13.1) and del(11q22.3) CLL. Alemtuzumab combination studies with fludarabine and/or monoclonal antibodies such as rituximab have demonstrated promising results. Alemtuzumab is also being studied in CLL patients as consolidation therapy for treatment of minimal residual disease, in preparation for stem cell transplantation and to prevent acute and chronic graft versus host disease. Alemtuzumab is frequently associated with acute 'first-dose' reactions when administered intravenously, but is much better tolerated when administered subcutaneously without loss of therapeutic efficacy. Additional potential adverse events associated with alemtuzumab administration include myelosuppression as well as profound cellular immune dysfunction with the associated risk of viral reactivation and other opportunistic infections. Additional studies detailing the mechanism of action of alemtuzumab as well as new strategies for prevention of opportunistic infections will aid in the future therapeutic development of this agent.

Epidemiological evidence of altered cardiac autonomic function in overweight but not underweight subjects.

BACKGROUND: Little is known about the altered cardiac autonomic function (CAF) across different levels of body mass index (BMI), including underweight, normal weight, overweight and obesity. This study provides a thorough analysis to clarify the CAF change in subjects with underweight, overweight and obesity. METHODS: According to the World Health Organization (WHO) Asia-Pacific BMI cutoffs, a total of 1437 participants were classified as underweight (n=74), normal weight (n=588), overweight (n=313), obesity I (n=390) and obesity II (n=72). CAF was determined by standard deviation of normal-to-normal (SDNN) intervals or RR intervals, power spectrum in low (LF) and high frequency (HF) (LF, 0.04-0.15 Hz; HF, 0.15-0.40 Hz), and LF/HF ratio at supine for 5 min, the ratio between the 30th and the 15th RR interval after standing from the supine position (30/15 ratio) and the average heart-rate change while taking six deep breaths in 1 min (HR(DB)). RESULTS: There were significant differences in age, gender, socioeconomic status, blood pressure, HOMA insulin resistance index, fasting glucose, cholesterol, triglyceride and high-density lipoprotein (HDL)-C, and the prevalence of hypertension, ischemic/left bundle branch block (LBBB) electrocardiography (EKG) pattern, current smoking and alcohol use among subjects with underweight, normal weight, overweight, obesity I and II. Univariate analysis showed that SDNN, HR(DB), HF power and the square root of the LF/HF ratio differed among these five groups. Multivariate analysis showed that obesity I and II were inverse correlates of HR(DB) and HF power. Overweight, obesity I and II were positively associated with the square root of the LF/HF ratio. No BMI status was related to SDNN, 30/15 ratio or LF power. Underweight was not the independent correlate of any CAF indices. CONCLUSIONS: The risk for altered CAF is significant in overweight and obese subjects, independent of cardiovascular risk factors. Underweight is not apparently associated with CAF change.

Filgrastim and alemtuzumab (Campath-1H) for refractory chronic lymphocytic leukemia.

Alemtuzumab (anti-CD52; Campath-1H) is effective in fludarabine-refractory chronic lymphocytic leukemia (CLL), but is associated with infection and early onset neutropenia. To reduce toxicity, filgrastim (G-CSF) was administered concurrently with alemtuzumab. In total, 14 CLL patients (median age 59) with a median of 3.5 prior regimens (range 1--12) received i.v. alemtuzumab, stepped up from 3 to 30 mg the first week, then 30 mg thrice weekly for 12 weeks. Filgrastim 5 microg/kg was administered daily 5 days before and throughout alemtuzumab therapy. Six patients developed cytomegalovirus (CMV) reactivation 3--6 weeks into treatment; six patients developed fever, three neutropenia, and one pneumonia. The patient with CMV pneumonia died; ganciclovir cleared CMV in the other patients. Five patients developed early neutropenia (weeks 2--5). Four patients developed delayed neutropenia (weeks 10--13) unassociated with CMV reactivation. Nine patients ceased therapy because of infectious and hematologic toxicity. Five partial responses were noted, all in patients with lymph nodes>cm, lasting a median of 6.5 months (range 5--13). Filgrastim and alemtuzumab were given concurrently with manageable infusion toxicity and clinical activity, but the efficacy of this regimen was limited by delayed neutropenia of unclear etiology and CMV reactivation. Filgrastrim should not be administered prophylactically during alemtuzumab therapy outside clinical trials.

Enhancement of the anticancer activity of bis(2-chloroethyl)nitrosourea in mice by coadministration of 2'-deoxyuridine, 2'-deoxycytidine, or thymidine.

The previous observation that the coadministration of a single dose of thymidine with the 3'-chloroethylnitrosourea analog of thymidine (3'-[3-(2-chloroethyl-3-nitrosoureido]-3'-deoxythymidine, 3'-CTNU) to mice bearing the L1210 or P388 leukemia enhanced the antitumor activity of 3'-CTNU, has led to a similar study of the potential effect on antitumor activity where thymidine, 2'-deoxyuridine, or 2'-deoxycytidine is coadministered with 1,3-bis(2-chloroethyl)-1-nitrosourea. Three levels of 1,3-bis(2-chloroethyl)-1-nitrosourea (10, 15, and 20 mg/kg) were coadministered to mice bearing the L1210 leukemia or the B16/F10 melanoma with each of the deoxyribonucleosides (2 g/kg). There was not only an increase in average days of survival of those that perished, but also a marked increase in the number of greater than 60-day survivors. The present report is a result of a determination of whether the augmented anticancer activity produced by a single injection of thymidine with 3'-CTNU was restricted to nitrosourea analogs of thymidine. The present study reveals not only that the phenomena of enhanced anticancer activity by the coadministration of thymidine can be extended to non-thymidine-containing nitrosoureas, but also that the coadministration of thymidine with 1,3-bis(2-chloroethyl)-1-nitrosourea produced an even more marked enhancement of antitumor activity than that previously observed when thymidine was coadministered with 3'-CTNU.

Changes in actin and actin-binding proteins during the differentiation of HL-60 leukemia cells.

Actin and actin-binding proteins form a peripheral network on the cytosolic side of the plasma membrane. These cytoskeleton proteins are involved in functions that require cellular movement and may also have a role in modulating signal transduction during cellular proliferation and differentiation. To measure changes in F-actin and actin-binding proteins during HL-60 differentiation, cells were induced to mature along the granulocytic pathway by exposure to 1 microM retinoic acid (RA) for 5 days and were analyzed for F-actin and actin-binding proteins by flow cytometry. The amounts of F-actin and spectrin in untreated HL-60 cells and in those undergoing differentiation by treatment with the retinoid did not differ. N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)-phallacidin was used to measure F-actin content and a monoclonal antibody followed by fluorescence isothiocyanate-conjugated goat anti-mouse immunoglobulin antibody was used to measure the content of spectrin; cells were analyzed by flow cytometry. In contrast, cells exposed to RA contained larger amounts of alpha-actinin, vinculin, talin, lipocortin I, and lipocortin II, as determined with their respective antibodies followed by flow cytometric analysis as described above. An RA-supersensitive clone of HL-60, designated HL-60/S4, exhibited lower constitutive levels of alpha-actinin, vinculin, and talin but a higher constitutive level of lipocortin II than parental cells. Treatment of HL-60/S4 with RA led to increases in vinculin, talin, lipocortin I, and lipocortin II. An RA-resistant clone, designated HL-60/R3, constitutively expressed larger amounts of alpha-actinin, vinculin, lipocortin I, and lipocortin II than parental HL-60 cells. Treatment of HL-60/R3 with RA resulted in decreases in the amounts of these actin-binding proteins. Changes in actin-binding proteins that occur during the differentiation of HL-60 cells suggest that these proteins may be of importance to the expression of the mature phenotype.

Comparative analysis of the immunosuppressive properties of two antiviral, iodinated thymidine analogs, 5-iodo-2'-deoxyuridine and 5-iodo-5'-amino-2',5'-dideoxyuridine.

5-Iodo-5'-amino-2',5'-dideoxyuridine (AldUrd), given as five single i.p. injections on Days 0 to 4 after antigenic challenge with sheep erythrocytes, had no demonstrable effect on serum hemagglutinin titers in doses as high as 2000 mg/kg/day. This was the maximum feasible single dose, but no 10% lethal dose was determinable. Similarly, 5-iodo-2'-deoxyuridine (IdUrd), 50 mg/kg/day (10% lethal dose), on Days 0 to 4 did not significantly affect this humoral response. However, with a more sensitive assay, immunocytoadherence, reductions in the number of hemagglutinin-forming cells in the spleen were found at several levels of AldUrd and IdUrd, but the same level of inhibition was attained by a course of AldUrd, 2000 mg/kg, or IdUrd, 50 mg/kg. Spleen cell-mediated immunity against lethally irradiated L1210 was measured by 4-hr 51Cr release and 48-hr growth inhibition assays. Both drugs showed dose-related immunosuppression. With AldUrd, 2000 mg/kg/day, and IdUrd, 100 mg/kg/day, on Days 0 to 4, cytotoxicity was inhibited by 35 to 68% and 73 to 90%, respectively. In comparison, a similar course of 1-beta-D arabinofuranosylcytosine, 40 mg/kg/day, completely abrogated both humoral and cell-mediated immunity. When AldUrd and IdUrd were administered on Days -5 to -1, little effect on either type of immunity was found, while pretreatment with the alkylating agent, cyclophosphamide, abolished all T-cell-mediated killing as measured on Day 7. Thus, AldUrd appears to be a very mild and IdUrd a moderate to strong cell cycle-dependent immunosuppressive.

Antitumor activity of the 3'-chloroethylnitrosourea analog of thymidine and the prevention by co-administered thymidine of lethality but not of anticancer activity.

The effect of the 3'-nitrosourea analog of thymidine (3'-[3-(2-chloroethyl)-3-nitrosoureido]-3'-deoxythymidine; 3'-CTNU) on the growth of the murine L1210 and P388 leukemias in mice was investigated. A single injection of 3'-CTNU (40 mg/kg) was minimally toxic to mice bearing the L1210 leukemia and produced 60-day survivors. The coadministration of thymidine did not prevent the initial loss of weight caused by 3'-CTNU but did prevent the lethality otherwise produced in non-tumor-bearing mice. A single dose of thymidine (2 g/kg) administered to L1210-bearing mice had no anticancer activity and when coadministered with 3'-CTNU had no detrimental effect on the potent antitumor effects of 3'-CTNU. Similar results were obtained against P388 leukemia. The hematopoietic toxicity produced by the administration of 3'-CTNU to non-tumor-bearing mice, as evidenced by changes in the white blood cells, neutrophil, and agar diffusion chamber precursor cell concentrations in the hematocrit and in bone marrow cellularity, could not be prevented by thymidine. Therefore, the lethality produced by 3'-CTNU is probably not related to hematopoietic toxicity since the coadministration of thymidine completely prevented any lethality.

STAT signaling in the pathogenesis and treatment of leukemias.

Leukemias continue to cause significant mortality in adults and children, and the use of standard cytotoxic chemotherapy has reached a therapeutic plateau. Thus, there is great interest in treatments directed against inappropriately activated cell signaling pathways which stimulate the uncontrolled growth of neoplastic cells. Increasing evidence suggests that the STAT signaling cascade may be one target of these therapies. Signal transducer and activator of transcription (STAT) proteins are critical in mediating the response of hematopoietic cells to a diverse spectrum of cytokines. Constitutive STAT activation is present in many malignancies and has been especially well characterized in acute and chronic leukemias. While STAT activation is a common characteristic of leukemias, the specific pattern of activated STATs and the manner by which STAT activation occurs vary with each disease. STAT tyrosine phosphorylation can occur through inappropriate Jak activation or by direct activation of an oncoprotein such as Bcr/Abl, and STAT serine phosphorylation may play an important role in leukemias as well. Thus, the STAT signaling pathway is an attractive target for therapeutic intervention, and strategies designed to inhibit STAT activation and STAT mediated gene transcription may play an important role in the next generation of anti-leukemia therapies. Oncogene (2000).

The effect of the nitrosourea analog of thymidine, 3'-[3-(2-chloroethyl)-3-nitrosoureido]-3'-deoxythymidine, on Escherichia coli thymidine kinase.

Escherichia coli thymidine kinase (ATP:thymidine 5'-phosphotransferase, EC 2.7.1.21) is irreversibly inactivated by incubation with 3'-[3-(2-chloroethyl)-3-nitrosoureido]-3'-deoxythymidine (3'-CTNU). The inactivation of the enzyme followed first-order kinetics even after loss of 96% of the original activity. This indicates that the inactivation process is a one-kill phenomenon and not a generation of less active enzyme. The addition of a preincubated aqueous solution of 3'-CTNU to the enzyme reaction mixture did not inactivate the enzyme. ATP . Mg2+ but not thymidine protects the enzyme from inactivation by 3'-CTNU. The allosteric regulators, dTTP, dCTP and dCDP also afforded complete protection of the enzyme from inactivation by 3'-CTNU. These data indicate that the dimer form of the enzyme is completely resistant to inactivation by 3'-CTNU, but the monomer form of the enzyme is sensitive. The specificity of the protection is supported by the finding that neither ATP . Mg2+ nor thymidine protect yeast alcohol dehydrogenase from inactivation by this nitrosourea analog of thymidine.