The present state of aspirin and clopidogrel resistance.

Antiplatelet therapy has demonstrated significant clinical benefit in the treatment of acute coronary syndrome. However, as with any treatment strategy it has been unable to prevent all cardiovascular events. This is far from surprising when considering the complexity of arterial thrombosis and more specifically platelet physiology. This lack of treatment success has provoked the introduction of various diagnostic tests and testing platforms with the intent of guiding and optimizing clinical treatment. Such tests have resulted in the generation of clinical data that suggest suboptimal response to antiplatelet agents such as aspirin and clopidogrel. In the case of both aspirin and clopidogrel, this suboptimal response has been termed resistance. Drug resistance would imply a lack of pharmacological response that has not been specifically investigated in many of the clinical studies performed to date. Rather, the term resistance has been used to describe various facets of platelet activation and aggregation relative to the testing method. Many of these measured parameters are not addressed in the therapeutic intent of the antiplatelet drug in question.

Electrochemiluminescence assays for insulin and glutamic acid decarboxylase autoantibodies improve prediction of type 1 diabetes risk.

We recently developed new electrochemiluminescence (ECL) insulin autoantibody (IAA) and glutamic acid decarboxylase 65 autoantibody (GADA) assays that discriminate high-affinity, high-risk diabetes-specific autoantibodies from low-affinity, low-risk islet autoantibodies (iAbs) detected by radioassay (RAD). Here, we report a further validation of the ECL-IAA and -GADA assays in 3,484 TrialNet study participants. The ECL assay and RAD were congruent in those with prediabetes and in subjects with multiple autoantibodies, but only 24% (P<0.0001) of single RAD-IAA-positive and 46% (P<0.0001) of single RAD-GADA-positive were confirmed by the ECL-IAA and -GADA assays, respectively. During a follow-up (mean, 2.4 years), 51% of RAD-IAA-positive and 63% of RAD-GADA-positive subjects not confirmed by ECL became iAb negative, compared with only 17% of RAD-IAA-positive (P<0.0001) and 15% of RAD-GADA-positive (P<0.0001) subjects confirmed by ECL assays. Among subjects with multiple iAbs, diabetes-free survival was significantly shorter if IAA or GADA was positive by ECL and negative by RAD than if IAA or GADA was negative by ECL and positive by RAD (P<0.019 and P<0.0001, respectively). Both positive and negative predictive values in terms of progression to type 1 diabetes mellitus were superior for ECL-IAA and ECL-GADA, compared with RADs. The prevalence of the high-risk human leukocyte antigen-DR3/4, DQB1*0302 genotype was significantly higher in subjects with RAD-IAA or RAD-GADA confirmed by ECL. In conclusion, both ECL-IAA and -GADA are more disease-specific and better able to predict the risk of progression to type 1 diabetes mellitus than the current standard RADs.

Urinary glucose and vitamin C.

The recent popularization of self-prescribed large doses of vitamin C has increased the possibility for erroneous conclusions to be drawn from standard clinical methods used in urinary glucose monitoring, due to interference with these methods by the greatly elevated excretion of vitamin C. The coupled-enzyme-chromogen strip tests showed erroneously negative glucose levels in urines of both a diabetic individual and a subject with a genetic low renal threshold for glucose when they were supplementing their normal diets with 1-2 g vitamin C per day. With this regimen, their urinary vitamin C levels reached 200 mg/dl (11.4 mmol/l). For normal urine with vitamin C added, false-positive tests for glucose were found using Benedict's reagent when vitamin C was present at 250 mg/dl (14.3 mmol/l) or higher concentrations. In diabetic individuals consuming large quantities of vitamin C, this interference with standard coupled-enzyme-chromogen strip tests or Benedict's test could present a significant problem in diagnosis and clinical management of the disease. A simple anion exchange method of treating the urine was used to correct the false results.

Clinical effects of fenfluramine on children with autism: a review of the research.

A review of research studies published to date on the effects of fenfluramine on children with autism is presented. The current status of the fenfluramine research on children with autism is assessed. The review analyzed the methodological aspects of the research, the toxicity of fenfluramine, and the relationship between fenfluramine, neurotransmitter activity, cognitive ability, and subsequent behavioral change. The review of published data indicated that fenfluramine had positive effects on the reduction of hyperactivity and stereotypic behaviors in 33% of the subjects. The best responders were children with the highest baseline IQs. The conclusions address the need for appropriate subgrouping of autistic syndromes, which may lead to identification of responders to pharmacological treatments. The need for further study of the possible long-term adverse side effects of flenfluramine is noted. Further experimental research on the effects of fenfluramine on children with autism is endorsed.

Hypocholesterolemic agents V: Inhibition of beta-hydroxy-beta-methylglutaryl coenzyme A reductase by substituted 4-biphenylylalkyl carboxylic acids and methyl esters.

Eleven substituted 4-biphenylylalkyl carboxylic acids and three methyl esters were synthesized and assayed for inhibition of rat liver beta-hydroxy-beta-methylglutaryl coenzyme A reductase. Five of the acids were analogs, resulting from various isosteric replacements of the carbonyl and ether oxygens of the previously described reversible inhibitor 1-(4-biphenylyl)pentyl hydrogen succinate. No significant change in activity was noted, except upon introduction of an amide linkage where a decrease in inhibition was found. Six carboxylic acids and three methyl esters, all containing the 4-biphenylyl radical but lacking the n-butyl side chain found in 1-(4-biphenylyl)pentyl hydrogen succinate, also were inhibitors of the reductase.

Hypocholesterolemic agents IV: inhibition of beta-hydroxy-beta-methyglutaryl coenzyme A reductase by arylalkenyl and arylepoxy hydrogen succinates and glutarates.

Two series of half acid esters of succinic and glutaric acids were synthesized and assayed for inhibition of rat liver beta-hydroxy-beta-methylglutaryl coenzyme A reductase. Irreversible inhibition was studied by incorporation of a potential alkylating group (the epoxide function) into the side chain of the alcohol portion of the half acid esters. Incorporation of a terminal olefin function into the side chain of the alcohol portion of the half acid esters provided a group that could form a charge-transfer complex. Neither irreversible inhibition nor formation of a charge-transfer complex was indicated from these studies; however, the two series of half acid esters exhibited reversible inhibition.

Hypocholesterolemic agents III: inhibition of beta-hydroxy-beta-methylglutaryl coenzyme A reductase by half acid esters of 1-(4-biphenylyl)pentanol.

A series of half acid esters of 1-(4-biphenylyl)pentanol was synthesized and assayed for inhibition of rat liver beta-hydroxy-beta-methylglutaryl coenzyme A reductase. The number of methylenes separating the carboxyl and ester groups was varied from zero to six. A minimum of one methylene was required for reasonable activity. Further separation of the carboxyl and ester groups produced small changes in activity. Investigation of several isomeric (cis and trans) half acid esters indicated that activity was independent of configuration. Modification of the acid portion of the glutarate analog by incorporating a 3-hydroxyl group increased activity sixfold.

A study of medical students and physicians referred for learning disabilities.

This study presents descriptive data on 86 medical students and physicians, referred for testing to determine the presence and type of learning problems. The major results indicate that most subjects had either a learning disability or attention deficit hyperactivity disorder (ADHD). Twenty-one subjects had a reading learning disability (LD); 21 subjects had a potential visual/spatial learning problem; 10 subjects had ADHD; 15 subjects had both a reading disability and ADHD; and 19 subjects had no detectable problem. Subtest analysis or WAIS-R scores indicated that sequential information processing may be the major difficulty for this sample.

Spelling improvement for college students who are dyslexic.

Academic problems of the dyslexic child often persist in adult life. Such problems as spelling can interfere with the performance of such adult learners in college. Federal legislation requires reasonable accommodation for these students. At some colleges, this consists of allowing use of tape recorders in lectures and sometimes allowing extra time on examinations. Remediation of reading, writing, and spelling among dyslexic college students is often not addressed. This study reports the use of a modified Orton-Gillingham approach in comparison with a nonphonetic approach and with a group receiving no remediation. The results indicate a significant increase in spelling performance for the group receiving the modified Orton-Gillingham remediation. This contrasts with no significant change in the group receiving nonphonetic remediation and in the control group (no remediation), and indicates that adulthood is not too late for appropriate intervention for the dyslexic student. Colleges offering such intervention and the students receiving it will benefit from improved performance.

Whole blood platelet function assay on the ICHOR point-of-care hematology analyzer.

The role of platelets as the initial defense against insult to the vasculature is well established. Moreover, platelets are now recognized as having a critical role in the acute care settings of cardiopulmonary bypass (CPB) procedures and cardiac catheterization. In the environment of CPB, both platelet count and function have been demonstrated as being markedly compromised during and following the procedure. Unfortunately, current assays that are used to evaluate the parameters of platelet count and function are limited in regard to their utility in a near patient format. Here, we describe a practical, rapid, and user-friendly whole blood platelet function assay that has been developed for the ICHOR point-of-care hematology analyzer. This analyzer is capable of performing an eight parameter blood profile including platelet count. In comparable studies, platelet aggregation in whole blood demonstrated good correlation (for ADP the values were n = 14, r2 = 0.81, p = 0.0001; for collagen, n = 10, r2 = 0.93, p = 0.0001; for ristocetin, n = 10, r2 = 0.89, p = 0.0001; and for epinephrine, n = 10, r2 = 0.81, p = 0.0003) with traditional platelet-rich aggregometry, which uses increased light transmission as an indication of platelet aggregation. Furthermore, early feasibility studies in CPB patients demonstrated both decreased platelet count and a marked reduction in platelet function peri-procedurally. This new assay of platelet function is extremely suitable for the clinical environment with rapid turnaround time and provides a full hematology profile to enhance transfusion decisions.

Statin therapy and thromboxane generation in patients with coronary artery disease treated with high-dose aspirin.

Aspirin and statin therapy are mainstay treatments in patients with coronary artery disease (CAD). The relation between statin therapy, in vivo thromboxane (Tx) generation; a marker of inflammation, and blood thrombogenicity has never been explored. Urinary 11-dehydro (dh) TxB2 was determined in patients with suspected CAD on 325 mg daily aspirin therapy prior to undergoing cardiac catheterisation (n=281). Thrombogenicity was estimated by thrombelastographic measurement of thrombin-induced platelet-fibrin clot strength (TIP-FCS) and lipids/lipoproteins were determined by vertical density gradient ultracentrifugation/ELISA. The influence of statin therapy and dose was analysed by the atorvastatin equivalent dose (5-10 mg, 20-40 mg, or 80 mg daily). Statin therapy (n=186) was associated with a dose-dependent reduction in urinary 11-dh TxB2 (p=0.046) that was independent of LDL and apo B100 levels but was strongly related to TIP-FCS (p=0.006). By multivariate analysis, no statin therapy (n=95) and female gender were independently associated with high urinary 11-dh TxB2 [OR=2.95 (0.1.57-5.50, p=0.0007); OR=2.25 (1.24-4.05, p=0.007)], respectively. In aspirin-treated patients, statin therapy was independently and inversely associated with inflammation in a dose-dependent manner. Elevated 11-dh TxB2 was associated with a prothrombotic state indicated by high TIP-FCS. Our data suggest that measurement of urinary 11-dTxB2 may be a useful method to optimise statin dosing in order to reduce thrombotic risk.

GAD65 autoantibodies detected by electrochemiluminescence assay identify high risk for type 1 diabetes.

The identification of diabetes-relevant islet autoantibodies is essential for predicting and preventing type 1 diabetes (T1D). The aim of the current study was to evaluate a newly developed electrochemiluminescence (ECL)-GAD antibody (GADA) assay and compare its sensitivity and disease relevance with standard radioassay. The assay was validated with serum samples from 227 newly diagnosed diabetic children; 68 prediabetic children who were prospectively followed to T1D; 130 nondiabetic children with confirmed islet autoantibodies to insulin, GAD65, IA-2, and/or ZnT8 longitudinally followed for 12 ± 3.7 years; and 181 age-matched, healthy, antibody-negative children. The ECL-GADA assay had a sensitivity similar to that of the standard GADA radioassay in children newly diagnosed with T1D, prediabetic children, and high-risk children with multiple positive islet autoantibodies. On the other hand, only 9 of 39 nondiabetic children with only a single islet autoantibody (GADA only) by radioassay were positive for ECL-GADA. GADA not detectable by ECL assay is shown to be of low affinity and likely not predictive of future diabetes. In conclusion, the new ECL assay identifies disease-relevant GADA by radioassay. It may help to improve the prediction and correct diagnosis of T1D among subjects positive only for GADA and no other islet autoantibodies.

Aspirin insensitive thromboxane generation is associated with oxidative stress in type 2 diabetes mellitus.

INTRODUCTION: Aspirin (ASA) irreversibly inhibits platelet cyclooxygenase-1 (COX-1) leading to decreased thromboxane-mediated platelet activation. The effect of ASA ingestion on platelet activation, thromboxane generation, oxidative stress and anti-oxidant biomarkers was studied in type 2 diabetes mellitus (DM). MATERIAL AND METHODS: Baseline and post-ASA samples (100/325 mg x 7 days) were obtained from 75 DM patients and 86 healthy controls for urinary 11-dehydro-thromboxane B2 (11 dhTxB2), 8-iso-prostaglandin-F2α (8-isoPGF2α) and serum sP-Selectin, nitrite (NO(2)(-)), nitrate (NO(3)(-)) and paraoxonase 1 (PON1) activity. RESULTS: Compared to baseline controls, baseline DM had higher mean levels of 11 dhTxB2 (3,665 ± 2,465 vs 2,450 ± 1,572 pg/mg creatinine, p=0.002), 8-isoPGF2α (1,457 ± 543 vs 1,009 ± 412 pg/mg creatinine, p<0.0001), NO(2)(-) (11.8 ± 7.3 vs 4.8 ± 5.3 µM, p<0.0001), NO(3)(-) (50.4 ± 39.3 vs 20.9 ± 16.7 µM, p<0.0001) and sP-Selectin (120.8 ± 56.7 vs 93.0 ± 26.1 ng/mL, p=0.02), and the same held for post-ASA levels (p<0.0001). ASA demonstrated no effect on 8-isoPGF2α, NO(2)(-), NO(3)(-), sP-Selectin or PON1 activity in either DM or controls. Post ASA inhibition of urinary 11 dhTxB2 was 71.5% in DM and 75.1% in controls. There were twice as many ASA poor responders in DM than in controls (14.8% and 8.4%) based on systemic thromboxane reduction. Urinary 8-isoPGF2α excretion was greater in DM ASA poor responders than good responders (p<0.009). CONCLUSIONS: This suggests that oxidative stress may maintain platelet function irrespective of COX-1 pathway inhibition and/or increase systemic generation of thromboxane from non-platelet sources.

Anatomy, biochemistry, and physiology laboratory programs in the education of physicians.

The amount of laboratory time devoted to anatomy, biochemistry, and physiology has decreased substantially while lecture time has remained essentially unchanged. Most laboratories consist of student conduction of assigned exercises with a sprinkling of demonstrations, conferences, and seminars. Various objectives for laboratory programs are discussed. A great percentage of the student's final anatomy grade (approximately 40%) still depends on his laboratory performance, while in biochemistry and physiology, lab work contributes only 12% and 10%, respectively, toward his final grade. There is great reluctance to abandon the laboratory program, however, because of the significant role it is thought to play in medical education.

Use of ICHOR-platelet works to assess platelet function in patients treated with GP IIb/IIIa inhibitors.

Platelet glycoprotein GP IIb/IIIa inhibitors have been recently approved for use in treating patients with acute coronary syndromes and those undergoing PCI. The purpose of this study was to assess the feasibility of using a new device, the ICHOR platelet works, to detect platelet inhibition in patients undergoing PCI and treated with abciximab or tirofiban. The study was conducted at Baylor College of Medicine, Houston, Texas. Thirty patients undergoing PCI and treated with abciximab (n = 10) or tirofiban (n = 20) are included. Blood samples were obtained before, at 30 min, at 4 hr, and at 12 hr after starting the GP IIb/IIIa inhibitors and 2 hr after discontinuation. Baseline studies revealed > 95% platelet aggregability in all patients after exposure to ADP (20 microM). After starting tirofiban, 82%, 83%, and 82% of platelets were inhibited at 30 min, 4 hr, and 12 hr. Platelet inhibition decreased to 43% 2 hr after discontinuation of tirofiban. Similarly, ICHOR platelet works detected 91%, 92%, and 85% platelet inhibition at 30 min, 4 hr, and 12 hr after starting abciximab, respectively. Platelet inhibition decreased to 73% 2 hr after discontinuation. The ICHOR platelet works is a promising, simple, and rapid bedside method that may have clinical utility in assessing platelet inhibition in patients treated with GP IIb/IIIa inhibitors. Cathet Cardiovasc Intervent 2001;53:346-351.