Reversible peptide folding in solution by molecular dynamics simulation

Long-standing questions on how peptides fold are addressed by the simulation at different temperatures of the reversible folding of a peptide in solution in atomic detail. Molecular dynamics simulations correctly predict the structure that is thermodynamically stable at 298 K, irrespective of the initial peptide conformation. The rate of folding and the free energy of folding at different temperatures are estimated. Although the conformational space potentially accessible to the peptide is extremely large, very few conformers (10(1) to 10(2)) are significantly populated at 20 K above the melting temperature. This implies that the search problem in peptide (or even protein) folding is surmountable using dynamics simulations.     

The pressure dependence of hydrophobic interactions is consistent with the observed pressure denaturation of proteins

Proteins can be denatured by pressures of a few hundred MPa. This finding apparently contradicts the most widely used model of protein stability, where the formation of a hydrophobic core drives protein folding. The pressure denaturation puzzle is resolved by focusing on the pressure-dependent transfer of water into the protein interior, in contrast to the transfer of nonpolar residues into water, the approach commonly taken in models of protein unfolding. Pressure denaturation of proteins can then be explained by the pressure destabilization of hydrophobic aggregates by using an information theory model of hydrophobic interactions. Pressure-denatured proteins, unlike heat-denatured proteins, retain a compact structure with water molecules penetrating their core. Activation volumes for hydrophobic contributions to protein folding and unfolding kinetics are positive. Clathrate hydrates are predicted to form by virtually the same mechanism that drives pressure denaturation of proteins.     

EASE vectors for rapid stable expression of recombinant antibodies

Over the past 10 years, monoclonal antibodies and antibody fragments have become an increasingly important source of therapeutic molecules in the biotechnology industry. Drug development strategies rely on screening large numbers of candidate molecules in search of an optimized drug candidate. This strategy requires efficient production of ten to a few hundred milligrams of candidate molecules for screening in bioassays and animal models. Typically, this amount of recombinant protein expression involves large numbers of transient transfections or cloning of a recombinant cell line. Both of these approaches are time-consuming and labor-intensive. In this report, we describe the application of an EASE vector system that is capable of generating stable pools of transfected Chinese hamster ovary cells. These pooled populations of cells produce high quantities of antibody candidates without labor-intensive cloning in a 3-5 week time frame. When an optimal drug candidate has been selected, pools generated with EASE-containing vectors can also be used in subsequent cloning steps to make cell lines with improved expression levels. We demonstrate that EASE increases expression in nonamplified pools in addition to increasing amplification and viability of clonal cell lines generated with the EASE-containing vectors compared with pools and cell lines generated without EASE.     

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.