Criterion level and instructional effects in the voluntary control of heart rate

Two experiments are reported. In experiment 1 the effects of different punishment criteria on the acquisition of voluntary control of heart rate was studied in three groups of 10 subjects. Punishment criterion was manipulated so that the 10, 30 and 50% most extreme interbeat intervals in the opposite direction from the desired heart rate change were punished. Subjects received four training sessions, two directed at increasing heart rate, and two at decreasing. Substantial bidirectional heart rate changes were obtained very early in training. Some weak evidence of criterion effects was obtained. In a supplementary experiment modelled on experiment 1, the instruction plus feedback used in experiment 1 were compared with instructions alone. Feedback did not aid heart rate control. In both experiments there was evidence of skeletal involvement in the heart rate change.     

A Phase II trial of flavopiridol (NSC #649890) in patients with previously untreated metastatic androgen-independent prostate cancer.

PURPOSE: Flavopiridol is a cyclin-dependent kinase inhibitor with preclinical activity against prostate cancer cell lines. A Phase II trial was conducted to determine the activity of flavopiridol in patients with metastatic hormone-refractory prostate cancer. EXPERIMENTAL DESIGN: A total of 36 patients was enrolled from several institutions and treated with a 72-h continuous infusion of flavopiridol every 14 days at the eventual starting dose of 40 mg/m(2)/day. Dose escalation up to 60 mg/m(2)/day was permitted if no significant toxicity was observed. Responses were assessed every 12 weeks. Only those patients completing four courses of the 72-h infusion were considered evaluable for response because the primary objective was to determine progression-free survival at 6 months given the cytostatic nature of the agent. RESULTS: This study was conducted in a two-stage fashion. During the first stage, at least 20 evaluable patients needed to be enrolled to assess response. There were 22 of 36 patients evaluable for response. No objective responses were observed. Only 4 patients had stable disease for 16, 26, 29, and 48 weeks, respectively, stopping the trial by design as only 3 of 22 (14%) of the patients met the 6-month progression-free survival end point. The most common toxicities were diarrhea (grade 1 and 2) and nausea, although some grade 3 and 4 diarrhea (11 and 6%, respectively) were evident. CONCLUSIONS: Flavopiridol has disappointing single-agent activity in hormone-refractory prostate cancer when administered at this dose and schedule. Its use in prostate cancer should be reserved for evaluation in combination therapies or alternative schedules.     

Characterization of human lymphocyte antigen class I antigen-processing machinery defects in renal cell carcinoma lesions with special emphasis on transporter-associated with antigen-processing down-regulation.

The HLA class I antigen-processing machinery (APM) plays a crucial role in the generation of peptides from endogenously synthesized proteins and in their presentation to cytotoxic T lymphocytes. The potential role of defects of APM components in immune escape mechanisms used by malignant cells has prompted us to analyze their expression in renal cell carcinoma (RCC) lesions with special emphasis on TAP because of its critical role in the loading of HLA class I antigens with peptides. Immunohistochemical staining of 51 formalin-fixed RCC lesions and autologous normal renal epithelium detected transporter associated with antigen processing (TAP)1 and tapasin deficiencies in 63 and 80% of the tumor lesions. Impaired low molecular weight protein (LMP)2 and LMP7 expression was found in 73 and 33% of the RCC lesions analyzed, respectively. In contrast to the high frequency of APM component down-regulation, HLA class I heavy chain and beta(2)-microglobulin defects were detected in only 12 and 10% of the lesions, respectively. Concomitant TAP1 and LMP2 deficiencies were found in approximately 57% of RCC lesions, whereas a coordinated down-regulation of all APM components occurred only in 5% of the tumor specimens analyzed. The presence of APM defects was independent of tumor stage and grade but varied significantly among the RCC subtypes. TAP abnormalities do not appear to be attributable to structural alterations because no mutations in TAP1 were detected in TAP1-deficient RCC lesions. These data suggest that TAP defects in RCC lesions are caused by regulatory abnormalities. Therefore, T-cell-based immunotherapy may benefit from the administration of cytokines that up-regulate TAP expression.     

Comparing the Discriminative Validity of Two Generic and One Disease-Specific Health-Related Quality of Life Measures in a Sample of Patients with Dry Eye

OBJECTIVE: The purpose of this study was to compare the discriminative properties of two generic health-related quality of life (QoL) instruments (SF-36 and EQ-5D) and a newly developed disease-specific patient-reported outcomes instrument (Impact of Dry Eye on Everyday Life (IDEEL)) to distinguish between different levels of dry eye severity. METHODS: Assessment of 210 people: 130 with non-Sjogren's Keratoconjunctivitis Sicca (non-SS KCS), 32 with Sj?gren's Syndrome (SS) and 48 controls; comparison of SF-36, EQ-5D, and IDEEL age-adjusted data by dry eye severity levels. Severity was assessed based on diagnosis (non-SS KCS, SS, control), patient-report (none, very mild, mild, moderate, severe, extremely severe) and clinician-report (none, mild, moderate, severe). RESULTS: Discriminative validity results were consistent for all instruments. Significant differences between severity levels were found with most SF-36 scales (P < 0.05), all EQ-5D scales (P < 0.05), and all IDEEL scales (P < 0.0001), except for Treatment Satisfaction. IDEEL scales consistently outperformed the generic QoL measures regardless of the severity criterion used. Most SF-36 scales outperformed the EQ-5D QoL scale, but the EQ-5D visual analog scale outperformed the SF-36 scales, except for General Health Perceptions. CONCLUSIONS: The disease-specific IDEEL scales are better able to discriminate between severity levels than the majority of the generic QoL scales. Preliminary evidence demonstrates that the IDEEL will be sensitive to QoL changes over time, although further testing in controlled longitudinal studies is needed.     

High-throughput physicochemical and in vitro ADMET screening

During drug discovery, it is important to optimise the affinity for the biomolecular target and also the properties of molecules that influence absorption, distribution, metabolism, excretion, and toxicity (ADMET). The goal is to improve the properties of a lead compound and select highly ‘developable’ candidates. Efficient pharmaceutical property profiling operations are now run in parallel to potency screening during lead optimization and provide data for compound prioritization and for the selection of compounds for in vivo studies. The main components of a profiling strategy suitable for early discovery are the measurement of selected physicochemical properties together with in vitro screening for metabolic stability. In addition, enzyme or cellular assays may be deployed for investigation of cellular permeability (including active and passive transport), plasma protein binding, toxicity, and the potential for drug-drug interactions. The four principal physicochemical parameters measured are lipophilicity, dissociation constant, permeability through artificial membranes, and aqueous solubility. An objective of property-based design is the identification of structure property relationships for ADMET that can suggest structural modifications that will also promote or retain high affinity for the biomolecular target. Sometimes this is not possible and new lead molecules may need to be identified to provide new starting points. A sub-optimal in vitro profile may be acceptable as long as there is a reasonable probability of achieving an adequate in vivo profile for clinical studies. In these cases, the application of composite models that can relate in vitro to in vivo behavior is important. Full ‘physiologically based pharmacokinetic’ (PBPK) models can be used; however, there are also simpler approaches available that may be adequate and more easily applied for ranking compounds within a series. Reliable in vitro—in vivo correlation is still very difficult because of the multiplicity of mechanisms involved. For the future, there is a need to develop better criteria for making mechanistically based classifications to develop differentiated models that are appropriate for different types of compound. It is also difficult to correct models for non-specific binding of drugs to membranes and proteins and we need better lipophilicity measures for accurately estimating the affinity of drugs for tissues. PBPK modeling leads to the exciting concept of the ‘virtual human’; however, PBPK models suitable for drug discovery applications are still in their infancy and it will be some time before their promise is fulfilled.     

Synergistic Effects of Clostridium perfringens Enterotoxin and Beta Toxin in Rabbit Small Intestinal Loops

The ability of Clostridium perfringens type C to cause human enteritis necroticans (EN) is attributed to beta toxin (CPB). However, many EN strains also express C. perfringens enterotoxin (CPE), suggesting that CPE could be another contributor to EN. Supporting this possibility, lysate supernatants from modified Duncan-Strong sporulation (MDS) medium cultures of three CPE-positive type C EN strains caused enteropathogenic effects in rabbit small intestinal loops, which is significant since CPE is produced only during sporulation and since C. perfringens can sporulate in the intestines. Consequently, CPE and CPB contributions to the enteropathogenic effects of MDS lysate supernatants of CPE-positive type C EN strain CN3758 were evaluated using isogenic cpb and cpe null mutants. While supernatants of wild-type CN3758 MDS lysates induced significant hemorrhagic lesions and luminal fluid accumulation, MDS lysate supernatants of the cpb and cpe mutants caused neither significant damage nor fluid accumulation. This attenuation was attributable to inactivating these toxin genes since complementing the cpe mutant or reversing the cpb mutation restored the enteropathogenic effects of MDS lysate supernatants. Confirming that both CPB and CPE are needed for the enteropathogenic effects of CN3758 MDS lysate supernatants, purified CPB and CPE at the same concentrations found in CN3758 MDS lysates also acted together synergistically in rabbit small intestinal loops; however, only higher doses of either purified toxin independently caused enteropathogenic effects. These findings provide the first evidence for potential synergistic toxin interactions during C. perfringens intestinal infections and support a possible role for CPE, as well as CPB, in some EN cases.