10-Formyl-5,8,10-trideazafolic acid (10-formyl-TDAF): a potent inhibitor of glycinamide ribonucleotide transformylase

The synthesis of 10-formyl-5,8,10-trideazafolic acid (3) as a potential inhibitor of glycinamide ribonucleotide transformylase (GAR Tfase) is reported. The target compound was prepared by a convergent synthesis utilizing the alkylation of hydrazone 5 with benzylic bromide 6 to construct the core heterocycle 7. The aldehyde 3 and related agents were evaluated as inhibitors of purN GAR Tfase and avian AICAR Tfase. Compound 3 exhibited potent inhibition of GAR Tfase with a Ki of 0.26 +/- 0.05 microM. In contrast, 3 exhibited more moderate inhibition of aminoimidazole carboxamide ribonucleotide transformylase (AICAR Tfase), with Ki of 7.6 +/- 1.5 microM.     

NIDDM: new aspects of management

Patients over age 40 should be made aware of the triad of risk factors for the disease and taught to recognize common signs and symptoms. Those with high-risk profiles should be tested regularly and counseled regarding preventive and therapeutic strategies. For obese patients whose weight cannot be brought under control with diet and exercise alone, a trial of anorectic agents should be considered.     

A life skills approach to mathematics instruction: preparing students with learning disabilities for the real-life math demands of adulthood

Current mathematics instruction does not address the day-to-day needs of many students with learning disabilities. Although the vast majority of students with learning disabilities are not college bound, much of mathematics instruction provides college preparation. Too often, classes in mathematics ignore the skills needed in home and community and on the job. The present article examines the ways in which general mathematics instruction, focused on daily living skills, can easily be integrated into the classrooms of students with learning disabilities.     

Economic implications of hepatic arterial infusion chemotherapy in treatment of nonresectable colorectal liver metastases. Meta-Analysis Group in Cancer

BACKGROUND: Approximately 20% of patients with colorectal cancer die of metastases confined to the liver. A meta-analysis recently performed by our group confirmed that in these patients hepatic arterial infusion of 5-fluoro-2'-deoxyuridine, compared with intravenous chemotherapy with fluoropyrimidines or supportive care (including symptom palliation when necessary), improved tumor response. PURPOSE: Because of the high cost of hepatic arterial infusion, we undertook a cost-effectiveness analysis that related the cost of such therapy to its medical efficacy. METHODS: The patient population was drawn from the seven randomized clinical trials included in the meta-analysis and included individual data on 654 patients. Of these seven trials, five compared hepatic arterial infusion and intravenous chemotherapy and two compared hepatic arterial infusion and a control group in which some patients could be left untreated. Patients assigned to receive hepatic arterial infusion made up the hepatic arterial infusion group; the other patients constituted the control group. The measures of efficacy were survival and tumor response. Health-care costs (in 1995 U.S. dollars) were computed over the duration of patient follow-up and were derived from actual costs in two centers, one at Henri Mondor Hospital (Paris, France) and the other at Stanford University Medical Center (Palo Alto, CA). The total cost of treatment included the initial procedure, chemotherapy cycles, and main complications. RESULTS: The mean gain in life expectancy in the hepatic arterial infusion group compared with the control group was 3.2 months (standard error = 1.0 month). For patients treated by hepatic arterial infusion in Paris, the hepatic arterial infusion pump, initial hospitalization, and the entire process (including follow-up and complications) cost, on average, $8400, $15172, and $29562, respectively; in Palo Alto, these costs were $4700, $13784, and $25 208, respectively. For patients in the control groups in Paris and Palo Alto, the total treatment costs were, on average, $9926 and $5928. The additional costs of hepatic arterial infusion over control treatment were $19636 in Paris and $19280 in Palo Alto. The cost-effectiveness (i.e., the additional cost divided by the additional benefit) with respect to survival of the patients in the hepatic arterial infusion group compared with the patients in the control group was $73635 per life-year in Paris and $72300 per life-year in Palo Alto. CONCLUSIONS AND IMPLICATIONS: The cost-effectiveness of localized chemotherapy for colorectal liver metastases is within the range of accepted treatments for serious medical conditions, although it might be considered borderline by policy-makers in some countries. Prospective clinical trials should be conducted to more definitively answer this question.     

Quantitative trait locus (QTL) mapping using different testers and independent population samples in maize reveals low power of QTL detection and large bias in estimates of QTL effects

The efficiency of marker-assisted selection (MAS) depends on the power of quantitative trait locus (QTL) detection and unbiased estimation of QTL effects. Two independent samples N = 344 and 107 of F2 plants were genotyped for 89 RFLP markers. For each sample, testcross (TC) progenies of the corresponding F3 lines with two testers were evaluated in four environments. QTL for grain yield and other agronomically important traits were mapped in both samples. QTL effects were estimated from the same data as used for detection and mapping of QTL (calibration) and, based on QTL positions from calibration, from the second, independent sample (validation). For all traits and both testers we detected a total of 107 QTL with N = 344, and 39 QTL with N = 107, of which only 20 were in common. Consistency of QTL effects across testers was in agreement with corresponding genotypic correlations between the two TC series. Most QTL displayed no significant QTL x environment nor epistatic interactions. Estimates of the proportion of the phenotypic and genetic variance explained by QTL were considerably reduced when derived from the independent validation sample as opposed to estimates from the calibration sample. We conclude that, unless QTL effects are estimated from an independent sample, they can be inflated, resulting in an overly optimistic assessment of the efficiency of MAS.     

Selective inhibition of syncytium-inducing and nonsyncytium-inducing HIV-1 variants in individuals receiving didanosine or zidovudine, respectively

By studying changes in the clonal composition of HIV-1 populations during the first weeks of zidovudine (ZDV) treatment before the development of ZDV resistance-conferring mutations, we demonstrated previously a selective inhibition of nonsyncytium-inducing (NSI) HIV-1, even when present as coexisting population in individuals also harboring syncytium-inducing (SI) HIV-1. In this study, we observed the opposite in individuals receiving didanosine (ddI) treatment. In these individuals (n = 7) a median -0.98 log change (range -1.55-0.08) in infectious cellular SI load was observed, whereas the coexisting NSI load was only minimally affected (median -0.15 log, range -1.27-0.50; P = 0.03). The virus phenotype-dependent treatment responses were independent of the clonal composition of HIV-1 populations at baseline. Individuals treated with a combination of ZDV and ddI revealed an equal decline of both NSI and SI infectious cellular load (n = 4; NSI: median -1.55 log, range -2.19 to -1.45; SI: median -1.47 log, range -1.81 to -0.86; P = 0.56). To test the hypothesis that the previously reported optimal activation of ZDV and ddI in activated and resting T cells, respectively, in combination with the differential T cell tropism of NSI and SI HIV-1 is the basis for the observed virus phenotype specific efficacy of nucleoside analogs, we studied the effect of treatment with a protease inhibitor that does not require intracellular activation. Individuals receiving ritonavir (n = 4) indeed showed equal declines in NSI and SI infectious cellular load (NSI: median -2.37 log, range -2.59 to -2.16; SI: median -2.82 log, range -3.14 to -2.50; P = 0.25). Our data suggest HIV-1 phenotype as an additional parameter in the design of optimal treatment regimens.     

Histopathologic validation of the sentinel lymph node hypothesis for breast carcinoma

BACKGROUND AND OBJECTIVE: The sentinel node hypothesis assumes that a primary tumor drains to a specific lymph node in the regional lymphatic basin. To determine whether the sentinel node is indeed the node most likely to harbor an axillary metastasis from breast carcinoma, the authors used cytokeratin immunohistochemical staining (IHC) to examine both sentinel and nonsentinel lymph nodes. METHODS: From February 1994 through October 1995, patients with breast cancer were staged with sentinel lymphadenectomy followed by completion level I and II axillary dissection. If the sentinel node was free of metastasis by hematoxylin and eosin staining (H&E), then sentinel and nonsentinel nodes were examined with IHC. RESULTS: The 103 patients had a median age of 55 years and a median tumor size of 1.8 cm (58.3% T1, 39.8% T2, and 1.9% T3). A mean of 2 sentinel (range, 1-8) and 18.9 nonsentinel (range, 7-37) nodes were excised per patient. The H&E identified 33 patients (32%) with a sentinel lymph node metastasis and 70 patients (68%) with tumor-free sentinel nodes. Applying IHC to the 157 tumor-free sentinel nodes in these 70 patients showed an additional 10 tumor-involved nodes, each in a different patient. Thus, 10 (14.3%) of 70 patients who were tumor-free by H&E actually were sentinel node-positive, and the IHC lymph node conversion rate from sentinel node-negative to sentinel node-positive was 6.4% (10/157). Overall, sentinel node metastases were detected in 43 (41.8%) of 103 patients. In the 60 patients whose sentinel nodes were metastasis-free by H&E and IHC, 1087 nonsentinel nodes were examined at 2 levels by IHC and only 1 additional tumor-positive lymph node was identified. Therefore, one H&E sentinel node-negative patient (1.7%) was actually node-positive (p < 0.0001), and the nonsentinel IHC lymph node conversion rate was 0.09% (1/1087; p < 0.0001). CONCLUSIONS: If the sentinel node is tumor-free by both H&E and IHC, then the probability of nonsentinel node involvement is <0.1%. The true false-negative rate of this technique using multiple sections and IHC to examine all nonsentinel nodes for metastasis is 0.97% (1/103) in the authors' hands. The sentinel lymph node is indeed the most likely axillary node to harbor metastatic breast carcinoma.     

Nitric oxide regulates cyclic GMP-dependent protein kinase phosphorylation in rat brain

Nitric oxide (NO) acts via soluble guanylyl cyclase to increase cyclic GMP (cGMP), which can regulate various targets including protein kinases. Western blotting showed that type II cGMP-dependent protein kinase (cGK II) is widely expressed in various brain regions, especially in the thalamus. In thalamic extracts, the phosphorylation of several proteins, including cGK II, was increased by exogenous NO or cGMP. In vivo pretreatment with a NO synthase inhibitor reduced the phosphorylation of cGK II, and this could be reversed by exogenous NO or cGMP. Conversely, brainstem electrical stimulation, which enhances thalamic NO release, caused a NO synthase-dependent increase in the phosphorylation of thalamic cGK II. These results indicate that endogenous NO regulates cGMP-dependent protein phosphorylation in the thalamus. The activation of cGKII by NO may play a role in thalamic mechanisms underlying arousal.