Interdisciplinary educational approaches in Healthcare Organizations

Background: Healthcare professionals’ perception of Interdisciplinary Education is an essential factor that affects their acceptance of this approach to education. From the literature related to patient safety, it has been identified widely that healthcare team communication and performance are critical to providing safe care to the patient. Poor organization and team dynamics among healthcare professionals appear to impact the safety and quality of patient care. The lack of Interdisciplinary Education in healthcare institutions in the Kingdom of Saudi Arabia negatively impacts the work dynamics of the healthcare team. Results: The study results showed that the majority of health care workers showed a high awareness level for IPE. Therefore, female nurses who have been working in special units and have experience of more than five years are perceived more than other specialties. Also, health workers in special units showed a higher percentage than in the general wards, and females were ready more than males. Only one item helped to determine the differences in perception which is the “perceived need for cooperation”. Conclusions: IPC should be initiated by universities than by health organizations starting at the level of leaders of medicine, nursing, and other disciplines who should be aware of the importance of IPC that would benefit patients as well as health institutions. Leaders must take IPC cooperation seriously by putting it into consideration in the vision of departments and thus starting to establish small-cooperated teams, which include various specialties.

Impact of common genetic determinants of Hemoglobin A1c on type 2 diabetes risk and diagnosis in ancestrally diverse populations: A transethnic genome-wide meta-analysis

BACKGROUND

Glycated hemoglobin (HbA1c) is used to diagnose type 2 diabetes (T2D) and assess glycemic control in patients with diabetes. Previous genome-wide association studies (GWAS) have identified 18 HbA1c-associated genetic variants. These variants proved to be classifiable by their likely biological action as erythrocytic (also associated with erythrocyte traits) or glycemic (associated with other glucose-related traits). In this study, we tested the hypotheses that, in a very large scale GWAS, we would identify more genetic variants associated with HbA1c and that HbA1c variants implicated in erythrocytic biology would affect the diagnostic accuracy of HbA1c. We therefore expanded the number of HbA1c-associated loci and tested the effect of genetic risk-scores comprised of erythrocytic or glycemic variants on incident diabetes prediction and on prevalent diabetes screening performance. Throughout this multiancestry study, we kept a focus on interancestry differences in HbA1c genetics performance that might influence race-ancestry differences in health outcomes.

METHODS & FINDINGS

Using genome-wide association meta-analyses in up to 159,940 individuals from 82 cohorts of European, African, East Asian, and South Asian ancestry, we identified 60 common genetic variants associated with HbA1c. We classified variants as implicated in glycemic, erythrocytic, or unclassified biology and tested whether additive genetic scores of erythrocytic variants (GS-E) or glycemic variants (GS-G) were associated with higher T2D incidence in multiethnic longitudinal cohorts (N = 33,241). Nineteen glycemic and 22 erythrocytic variants were associated with HbA1c at genome-wide significance. GS-G was associated with higher T2D risk (incidence OR = 1.05, 95% CI 1.04-1.06, per HbA1c-raising allele, p = 3 × 10-29); whereas GS-E was not (OR = 1.00, 95% CI 0.99-1.01, p = 0.60). In Europeans and Asians, erythrocytic variants in aggregate had only modest effects on the diagnostic accuracy of HbA1c. Yet, in African Americans, the X-linked G6PD G202A variant (T-allele frequency 11%) was associated with an absolute decrease in HbA1c of 0.81%-units (95% CI 0.66-0.96) per allele in hemizygous men, and 0.68%-units (95% CI 0.38-0.97) in homozygous women. The G6PD variant may cause approximately 2% (N = 0.65 million, 95% CI 0.55-0.74) of African American adults with T2D to remain undiagnosed when screened with HbA1c. Limitations include the smaller sample sizes for non-European ancestries and the inability to classify approximately one-third of the variants. Further studies in large multiethnic cohorts with HbA1c, glycemic, and erythrocytic traits are required to better determine the biological action of the unclassified variants.

CONCLUSIONS

As G6PD deficiency can be clinically silent until illness strikes, we recommend investigation of the possible benefits of screening for the G6PD genotype along with using HbA1c to diagnose T2D in populations of African ancestry or groups where G6PD deficiency is common. Screening with direct glucose measurements, or genetically-informed HbA1c diagnostic thresholds in people with G6PD deficiency, may be required to avoid missed or delayed diagnoses.

GRECOS Project (Genotyping Recurrence Risk of Stroke): The Use of Genetics to Predict the Vascular Recurrence After Stroke

BACKGROUND AND PURPOSE

Vascular recurrence occurs in 11% of patients during the first year after ischemic stroke (IS) or transient ischemic attack. Clinical scores do not predict the whole vascular recurrence risk; therefore, we aimed to find genetic variants associated with recurrence that might improve the clinical predictive models in IS.

METHODS

We analyzed 256 polymorphisms from 115 candidate genes in 3 patient cohorts comprising 4482 IS or transient ischemic attack patients. The discovery cohort was prospectively recruited and included 1494 patients, 6.2% of them developed a new IS during the first year of follow-up. Replication analysis was performed in 2988 patients using SNPlex or HumanOmni1-Quad technology. We generated a predictive model using Cox regression (GRECOS score [Genotyping Reurrence Risk of Stroke]) and generated risk groups using a classification tree method.

RESULTS

The analyses revealed that rs1800801 in the MGP gene (hazard ratio, 1.33; P=9×10^-03), a gene related to artery calcification, was associated with new IS during the first year of follow-up. This polymorphism was replicated in a Spanish cohort (n=1.305); however, it was not significantly associated in a North American cohort (n=1.683). The GRECOS score predicted new IS (P=3.2×10^-09) and could classify patients, from low risk of stroke recurrence (1.9%) to high risk (12.6%). Moreover, the addition of genetic risk factors to the GRECOS score improves the prediction compared with previous Stroke Prognosis Instrument-II score (P=0.03).

CONCLUSIONS

The use of genetics could be useful to estimate vascular recurrence risk after IS. Genetic variability in the MGP gene was associated with vascular recurrence in the Spanish population.

Circulating cellular adhesion molecules and risk of diabetes: the Multi-Ethnic Study of Atherosclerosis (MESA)

AIMS

To test the hypothesis that soluble cellular adhesion molecules would be positively and independently associated with risk of diabetes.

METHODS

Soluble levels of six cellular adhesion molecules (ICAM-1, E-selectin, VCAM-1, E-cadherin, L-selectin and P-selectin) were measured in participants in the Multi-Ethnic Study of Atherosclerosis, a prospective cohort study. Participants were then followed for up to 10 years to ascertain incident diabetes.

RESULTS

Sample sizes ranged from 826 to 2185. After adjusting for age, sex, race/ethnicity, BMI and fasting glucose or HbA1c , four cellular adhesion molecules (ICAM-1, E-selectin, VCAM-1 and E-cadherin) were positively associated with incident diabetes and there was a statistically significant trend across quartiles. Comparing the incidence of diabetes in the highest and lowest quartiles of each cellular adhesion molecule, the magnitude of association was largest for E-selectin (hazard ratio 2.49; 95% CI 1.26-4.93) and ICAM-1 (hazard ratio 1.76; 95% CI 1.22-2.55) in fully adjusted models. Tests of effect modification by racial/ethnic group and sex were not statistically significant for any of the cellular adhesion molecules (P > 0.05).

CONCLUSIONS

The finding of significant associations between multiple cellular adhesion molecules and incident diabetes may lend further support to the hypothesis that microvascular endothelial dysfunction contributes to risk of diabetes.

P-selectin and subclinical and clinical atherosclerosis: the Multi-Ethnic Study of Atherosclerosis (MESA)

OBJECTIVE

P-selectin is a cellular adhesion molecule that has been shown to be crucial in development of coronary heart disease (CHD). We sought to determine the role of P-selectin on the risk of atherosclerosis in a large multi-ethnic population.

METHODS

Data from the Multi-Ethnic Study of Atherosclerosis (MESA), including 1628 African, 702 Chinese, 2393 non-Hispanic white, and 1302 Hispanic Americans, were used to investigate the association of plasma P-selectin with CHD risk factors, coronary artery calcium (CAC), intima-media thickness, and CHD. Regression models were used to investigate the association between P-selectin and risk factors, Tobit model for CAC, and Cox regression for CHD events.

RESULTS

Mean levels of P-selectin differed by ethnicity and were higher in men (P<0.001). For all ethnic groups, P-selectin was positively associated with measures of adiposity, blood pressure, current smoking, LDL, and triglycerides and inversely with HDL. A significant ethnic interaction was observed for the association of P-selectin and prevalent diabetes; however, P-selectin was positively associated with HbA1c in all groups. Higher P-selectin levels were associated with greater prevalence of CAC. Over 10.1 years of follow-up, there were 335 incident CHD events. There was a positive linear association between P-selectin levels and rate of incident CHD after adjustment for traditional risk factors. However, association was only significant in non-Hispanic white Americans (HR: 1.81, 95% CI 1.07 to 3.07, P=0.027).

CONCLUSION

We observed ethnic heterogeneity in the association of P-selectin and risk of CHD.

Detecting signals in pharmacogenomic genome-wide association studies

In one common pharmacogenomic scenario, outcome measures are compared for treated and untreated subjects across genotype defined subgroups. The key question is whether treatment benefit (or harm) is particularly strong in certain subgroups, and therefore statistical analysis focuses on the interaction between treatment and genotype. However, genome-wide analysis in such scenarios requires careful statistical thought since, in addition to the usual problems of multiple testing, the marker-defined sample sizes, and therefore power, vary across the individual genotypes being evaluated. The variability in power means the usual practice of using a common p-value threshold across tests has difficulties. The reason is that the use of a fixed threshold, with variable power, implies that the costs of type I and type II errors are varying across tests in a manner which is implicit rather than dictated by the analyst. In this paper we discuss this problem and describe an easily implementable solution based on Bayes factors. We pay particular attention to the specification of priors, which is not a straightforward task. The methods are illustrated using data from a randomized controlled clinical trial in which homocysteine levels are compared in individuals receiving low and high doses of folate supplements and across marker subgroups. The method we describe is implemented in the R computing environment with code available from http://faculty.washington.edu/jonno/cv.html.

Abstract 330: Ethnic Variability in the Association of Pulse Pressure with Adhesion Pathway Proteins: The Multi-Ethnic Study of Atherosclerosis (MESA) Study

Pulse pressure (PP), defined as the difference between systolic and diastolic blood pressure, is considered a marker of large artery stiffness and has been shown to independently predict cardiovascular disease. Differences among ethnicities with regard to PP have been previously described, yet the underlying biological mechanisms are poorly understood. In addition, biomarkers of inflammation and matrix remodeling have been shown to be involved in the development of arterial stiffness. The aim of this study was to investigate the role of adhesion pathway components in the development of arterial stiffness measured by PP among four ethnicities. E-cadherin, HGF, L-selectin, P-selectin, 6-Ckine, MMP1, MMP2, RANTES, SDF1, SLPI, TGFβ1, TIMP2 and VCAM were measured in a random sample of 2402 participants (579 African Americans, 619 Caucasians, 600 Chinese and 604 Hispanics) in the Multi-Ethnic Study of Atherosclerosis (MESA) study at Exam 2. PP was measured concurrently and its association with each adhesion protein level was assessed via linear regression in each ethnicity. All analyses were adjusted for age, sex, and traditional cardiovascular risk factors. Mean PP was significantly different among ethnicities: 55.9±18.0 mmHg in African Americans, 52.1± 16.1 mmHg in Caucasians, 51.4±16.4 mmHg in Chinese, and 55.0±17.5 in Hispanics, p<0.001. MMP2 was positively associated with PP among African Americans (β=2.3 (0.6), p<0.001) and Caucasians (β=1.7 (0.5), p=0.001); TIMP2 among Caucasians (β=1.5 (0.5), p=0.002) and to a lesser extent among African Americans (β=1.2 (0.6) p=0.050) and Chinese (β=1.3 (0.6), p=0.034). SDF1 was associated to PP in African Americans (β=1.4 (0.6), p=0.017) and in Chinese (β=1.1 (0.5), p=0.042); finally an association existed between TGFβ1 and PP in C (β=1.1 (0.5), p=0.025). None of the studied proteins was associated with PP in Hispanics. In conclusion, components of the adhesion pathway were correlated to PP in this large multi-ethnic cohort, possibly giving new insight on the pathophysiology of arterial stiffness. In addition, heterogeneity by ethnicity suggests different mechanisms in the development of arterial stiffness.

Genetic risk factors for ischaemic stroke and its subtypes (the METASTROKE collaboration): a meta-analysis of genome-wide association studies

BACKGROUND

Various genome-wide association studies (GWAS) have been done in ischaemic stroke, identifying a few loci associated with the disease, but sample sizes have been 3500 cases or less. We established the METASTROKE collaboration with the aim of validating associations from previous GWAS and identifying novel genetic associations through meta-analysis of GWAS datasets for ischaemic stroke and its subtypes.

METHODS

We meta-analysed data from 15 ischaemic stroke cohorts with a total of 12 389 individuals with ischaemic stroke and 62 004 controls, all of European ancestry. For the associations reaching genome-wide significance in METASTROKE, we did a further analysis, conditioning on the lead single nucleotide polymorphism in every associated region. Replication of novel suggestive signals was done in 13 347 cases and 29 083 controls.

FINDINGS

We verified previous associations for cardioembolic stroke near PITX2 (p=2·8×10(-16)) and ZFHX3 (p=2·28×10(-8)), and for large-vessel stroke at a 9p21 locus (p=3·32×10(-5)) and HDAC9 (p=2·03×10(-12)). Additionally, we verified that all associations were subtype specific. Conditional analysis in the three regions for which the associations reached genome-wide significance (PITX2, ZFHX3, and HDAC9) indicated that all the signal in each region could be attributed to one risk haplotype. We also identified 12 potentially novel loci at p<5×10(-6). However, we were unable to replicate any of these novel associations in the replication cohort.

INTERPRETATION

Our results show that, although genetic variants can be detected in patients with ischaemic stroke when compared with controls, all associations we were able to confirm are specific to a stroke subtype. This finding has two implications. First, to maximise success of genetic studies in ischaemic stroke, detailed stroke subtyping is required. Second, different genetic pathophysiological mechanisms seem to be associated with different stroke subtypes.

FUNDING

Wellcome Trust, UK Medical Research Council (MRC), Australian National and Medical Health Research Council, National Institutes of Health (NIH) including National Heart, Lung and Blood Institute (NHLBI), the National Institute on Aging (NIA), the National Human Genome Research Institute (NHGRI), and the National Institute of Neurological Disorders and Stroke (NINDS).

16S rRNA survey revealed complex bacterial communities and evidence of bacterial interference on human adenoids

Adenoid microbiota plays an important role in the development of various infectious and non-infectious diseases of the upper airways, such as otitis media, adenotonsillitis, rhinosinusitis and adenoid hypertrophy. Studies have suggested that adenoids could act as a potential reservoir of opportunistic pathogens. However, previous bacterial surveys of adenoids were mainly culture based and therefore might only provide an incomplete and potentially biased assessment of the microbial diversity. To develop an in-depth and comprehensive understanding of the adenoid microbial communities and test the 'pathogen reservoir hypothesis', we carried out a 16S rRNA based, culture-independent survey of bacterial communities on 67 human adenoids removed by surgery. Our survey revealed highly diverse adenoid bacterial communities distinct from those of other body habitats. Despite large interpersonal variations, adenoid microbiota shared a core set of taxa and can be classified into at least five major types based on its bacterial species composition. Our results support the 'pathogen reservoir hypothesis' as we found common pathogens of otitis media to be both prevalent and abundant. Co-occurrence analyses revealed evidence consistent with the bacterial interference theory in that multiple common pathogens showed 'non-coexistence' relationships with non-pathogenic members of the commensal microflora.

Are myocardial infarction--associated single-nucleotide polymorphisms associated with ischemic stroke?

BACKGROUND AND PURPOSE

Ischemic stroke (IS) shares many common risk factors with coronary artery disease (CAD). We hypothesized that genetic variants associated with myocardial infarction (MI) or CAD may be similarly involved in the etiology of IS. To test this hypothesis, we evaluated whether single-nucleotide polymorphisms (SNPs) at 11 different loci recently associated with MI or CAD through genome-wide association studies were associated with IS.

METHODS

Meta-analyses of the associations between the 11 MI-associated SNPs and IS were performed using 6865 cases and 11 395 control subjects recruited from 9 studies. SNPs were either genotyped directly or imputed; in a few cases a surrogate SNP in high linkage disequilibrium was chosen. Logistic regression was performed within each study to obtain study-specific βs and standard errors. Meta-analysis was conducted using an inverse variance weighted approach assuming a random effect model.

RESULTS

Despite having power to detect odds ratio of 1.09-1.14 for overall IS and 1.20-1.32 for major stroke subtypes, none of the SNPs were significantly associated with overall IS and/or stroke subtypes after adjusting for multiple comparisons.

CONCLUSIONS

Our results suggest that the major common loci associated with MI risk do not have effects of similar magnitude on overall IS but do not preclude moderate associations restricted to specific IS subtypes. Disparate mechanisms may be critical in the development of acute ischemic coronary and cerebrovascular events.

Abstract 2385: Investigation Of Aromatase Gene (CYP19A1) Variations In Stroke Patients

Introduction: Estrogens have been associated with risk of stroke in both men and women. Estradiol and estrone are synthesized from testosterone via the aromatase enzyme in both men and postmenopausal women. Genetic variation affecting function of the aromatase gene (CYP19A1) has been linked to elevated estradiol levels. We tested the hypothesis that these variants, as well as a modifying gene, are associated with ischemic stroke in three cohorts: the Vitamin Intervention for Stroke Prevention trial (VISP), Women’s Health Initiative (WHI), and Genetic Susceptibility to Early-Onset Stroke study (GEOS).

Methods: Genomic data for individuals of European descent with ischemic stroke was compared against an equal number of controls: VISP (1723 cases - 65% men), WHI (436 cases - all postmenopausal women), GEOS (557 cases - all men age <55). Genotyping was funded through the Genomics and Randomized Trials Network (GARNET) and Gene Environment Association Studies (GENEVA) consortia. All cohorts used the Illumina Omni1-Quad chip for genotyping with imputation as needed. Eight candidate single nucleotide polymorphisms (SNPs) in CYP19A1 on chromosome 15 and an additional regulatory SNP in a modifier locus on chromosome 8 were chosen for analysis due to coding status or previous association with estradiol levels. Analyses were adjusted for age, hormone therapy use (women), and the top three principal components. Association results were determined as odds ratios for individual SNPs (effect allele = minor), with significance level of p<0.05.

Results: GWAS results are tabulated. There were no significant differences in allele frequency for four SNPs in CYP19A1 among stroke patients and controls. The additional four SNPs were monomorphic in all three populations. The modifier gene SNP (rs1864729) was less common among young men with prior stroke in GEOS, but not men in VISP or in women.

Conclusions: Aromatase genetic variation was not associated with risk of stroke in these three cohorts. One SNP that modifies aromatase function was less common among young, but not older men with stroke. Replication in other studies is necessary.

Mutations at the BLK locus linked to maturity onset diabetes of the young and beta-cell dysfunction

Maturity-onset diabetes of the young (MODY) is a subtype of diabetes defined by an autosomal pattern of inheritance and a young age at onset, often before age 25. MODY is genetically heterogeneous, with 8 distinct MODY genes identified to date and more believed to exist. We resequenced 732 kb of genomic sequence at 8p23 in 6 MODY families unlinked to known MODY genes that showed evidence of linkage at that location. Of the 410 sequence differences that we identified, 5 had a frequency <1% in the general population and segregated with diabetes in 3 of the families, including the 2 showing the strongest support for linkage at this location. The 5 mutations were all placed within 100 kb corresponding to the BLK gene. One resulted in an Ala71Thr substitution; the other 4 were noncoding and determined decreased in vitro promoter activity in reporter gene experiments. We found that BLK--a nonreceptor tyrosine-kinase of the src family of proto-oncogenes--is expressed in beta-cells where it enhances insulin synthesis and secretion in response to glucose by up-regulating transcription factors Pdx1 and Nkx6.1. These actions are greatly attenuated by the Ala71Thr mutation. These findings point to BLK as a previously unrecognized modulator of beta-cell function, the deficit of which may lead to the development of diabetes.

Multiple sclerosis: a haplotype association study

Results are presented from a genomewide haplotype association study on multiple sclerosis (MS) cases from Tasmania, an island state of Australia. Cases were ascertained on strict clinical and radiological grounds and on the fact that they had at least one grandparent born in the state. This enriched for early settler chromosomes among present day Tasmanians with MS and increased the chances of finding common haplotype sharing at disease predisposition loci in distant relatives sharing common ancestral haplotypes. Four-to-five close relatives were also collected for each of 170 cases and 105 population-based controls. All were genotyped at a 5cM resolution, haplotypes reconstructed and sharing estimated using an empirical approach based on sorting haplotypes to find the most common at each locus and then generating a test statistic for excess sharing in the cases based on permutation testing. Five initial loci were found where there was an excess sharing in the cases. These were fine-mapped with 10-12 additional markers. Only loci on chromosomes 6 and 10 remained after fine mapping. These loci demonstrate an increase in sharing of multi-marker haplotypes in MS cases compared to both population control transmitted haplotypes and case non-transmitted haplotypes.

Greater quinidine-induced QTc interval prolongation in women

BACKGROUND

Prolongation of the electrocardiographic QT interval by drugs is associated with the occurrence of a potentially lethal form of polymorphic ventricular tachycardia termed torsades de pointes. Women are at greater risk than men for development of this adverse event when taking drugs that prolong the QT interval. To determine whether this may be the result of gender-specific differences in the effect of quinidine on cardiac repolarization, we compared the degree of quinidine-induced QT interval lengthening in healthy young men and women.

METHODS

Twelve women and 12 men received a single intravenous dose of quinidine (4 mg/kg) or placebo in a single-blind, randomized crossover trial. Total plasma and protein-free concentrations of quinidine and 3-hydroxyquinidine were measured in serum. QT intervals were determined and corrected for differences in heart rate with use of the method of Bazett (QTc = QT/RR1/2).

RESULTS

As expected, the mean QTc interval at baseline was longer for women than for men (mean +/- SD; 407 +/- 7 versus 395 +/- 9 ms, P < .05). The slope of the relationship between change in the QTc interval (delta QTc) from baseline to the serum concentration of quinidine was 44% greater for women than for men (mean +/- SE; 42.2 +/- 3.4 versus 29.3 +/- 2.6 ms/microg per mL, P < .001). These results were not influenced by analysis of 3-hydroxyquinidine, free concentrations of quinidine and 3-hydroxyquinidine, or the JT interval.

CONCLUSIONS

Quinidine causes greater QT prolongation in women than in men at equivalent serum concentrations. This difference may contribute to the greater incidence of drug-induced torsades de pointes observed in women taking quinidine and has implications for other cardiac and noncardiac drugs that prolong the QTc interval. Adjustment of dosages based on body size alone are unlikely to substantially reduce the increased risk of torsades de pointes in women.

Evaluation of markers on human chromosome 10, including the homologue of the rodent Rf-1 gene, for linkage to ESRD in black patients

There is abundant evidence supporting the contribution of genetic factors to the development of end-stage renal disease (ESRD) in blacks. Two renal failure susceptibility genes, Rf-1 and Rf-2, have been identified in the fawn-hooded rat, an animal model of hypertension and nephrosclerosis. The human homologous region containing the rodent Rf-1 gene has been localized to chromosome 10q. We tested for genetic linkage between 21 polymorphic markers on human chromosome 10 and chronic renal failure in 129 black sibling pairs concordant for ESRD. Two adjacent markers on 10p, D10S1435 and D10S249 (4 centiMorgans from D10S1435), approached significance for linkage to ESRD in sibling pairs with nondiabetic causes of ESRD (P = 0.035 pairwise, P = 0.082 multipoint for D10S1435; P = 0.074 pairwise, P = 0.063 multipoint for D10S249). The markers spanning the homologous region of Rf-1 did not show evidence for linkage to ESRD in sibling pairs concordant for diabetic ESRD, sibling pairs concordant for nondiabetic causes of ESRD, or in the entire family set. These results suggest that the human homologue of Rf-1 is unlikely to contribute substantially to renal failure susceptibility from the common causes of kidney disease in blacks.

Phase I trial of Marimastat, a novel matrix metalloproteinase inhibitor, administered orally to patients with advanced lung cancer

PURPOSE

This phase I study was performed to evaluate the safety and pharmacokinetics of escalating doses of Marimastat (British Biotech, Inc, Oxford, United Kingdom) in patients with advanced malignancies and to determine the phase II recommended dose to be used in subsequent studies.

PATIENTS AND METHODS

A standard phase I design was used in this study, in which consecutive groups of three patients were treated with escalating doses of the study drug. Marimastat was administered orally at 25, 50, or 100 mg twice daily to consecutive groups of patients with advanced lung cancer. An additional three patients were added at the highest dose studied (100 mg orally twice daily) to assess whether the inflammatory polyarthitis observed at that dose level can be prevented by a concurrent administration of nonsteroidal antiinflammatory drugs (NSAIDS) and/or low-dose corticosteroids. Blood was drawn for safety monitoring, pharmacokinetic analysis, and plasma levels of metalloproteinase (MMP)-2 and MMP-9 (determined by zymography). A total of 12 patients were studied.

RESULTS

The most significant toxicity at the highest dose studied (100 mg orally twice daily) was a symptomatic inflammatory polyarthritis that persisted for up to 8 weeks after discontinuation of the study drug and was dose-limiting. The estimated plasma elimination half-life of Marimastat was 4 to 5 hours. The mean maximum concentration (Cmax) at a reasonably well-tolerated dose (50 mg orally twice daily) was 196 ng/mL and was reached within 1 to 2 hours (Tmax) after administration. Areas under the curve (AUC) tended to correlate with the dose of Marimastat. Zymographic analysis of peripheral-blood ratios of activated proenzymatic forms of MMP-2 and -9 did not show any consistent patterns of change in MMP levels or in a degree of their activation during the course of treatment.

CONCLUSION

Marimastat was well absorbed from the gastrointestinal tract, with high levels of the study drug detected in plasma within hours after drug administration. Plasma concentrations of Marimastat achieved at dose levels 2 and 3 (50 mg and 100 mg orally twice daily) were substantially higher than those required for MMP inhibition in vitro. The dose-limiting toxicity (DLT) was severe inflammatory polyarthritis, which seemed to be a cumulative toxicity.

Alterations in heart rate following radiofrequency ablation in the treatment of reentrant supraventricular arrhythmias: relation to alterations in autonomic tone

To determine the relation between the creation of endocardial lesions and alterations in autonomic tone, we analyzed heart rate variability in patients undergoing radiofrequency catheter ablation for symptomatic supraventricular tachycardia. Elevated heart rates are frequently noted after radiofrequency catheter ablation for supraventricular arrhythmias. It has been postulated that this elevation may be secondary to alterations in cardiac autonomic tone. Since heart rate variability is a measure of autonomic nervous system activity, we used this technique to examine the heart rate elevation and to characterize postablation autonomic changes. Thirty-eight patients undergoing 44 radiofrequency catheter ablation procedures were included in the study. Total arrhythmic substrates treated included 34 accessory pathways and 13 AV nodes with dual physiology. Twenty-four hour ambulatory electrocardiographic recordings were obtained in a drug-free state prior to, ablation early postablation, and late postablation. Spectral and nonspectral analyses of heart rate variability were performed. Subgroup analyses were also done on specific cohorts. Subgroups included patients undergoing accessory pathway ablations, AV node modifications, and ablation of septal and nonseptal targets. To determine whether the amount of tissue damage was related to changes in heart rate variability, we analyzed the relation between the total energy delivered to the endocardium and the peak change in creatine kinase and heart rate variability. In this population, a significant transient increase in heart rate was noted following radiofrequency ablation. All time and frequency domain parameters of heart rate variability showed significant reversible decreases. These changes were independent of target site and arrhythmia substrate. There was no correlation noted between the changes in heart rate variability and either the total amount of energy applied to the endocardium or the change in creatine kinase. Increased heart rates and decreased heart rate variability occur following radiofrequency catheter ablation for supraventricular tachycardia. Clinically, the predominant effect is that of decreased parasympathetic tone. Since these transient changes are independent of arrhythmic substrate or ablation site in the atria, a rich parasympathetic innervation of the heart is proposed.

Linkage of genetic markers on human chromosomes 20 and 12 to NIDDM in Caucasian sib pairs with a history of diabetic nephropathy

The potential contribution of maturity-onset diabetes of the young (MODY) genes to NIDDM susceptibility in African-American and Caucasian NIDDM-affected sibling pairs with a history of adult-onset diabetic nephropathy has been evaluated. Evidence for linkage to NIDDM was found with polymorphic loci that map to the long arms of human chromosomes 20 and 12 in regions containing the MODY1 and MODY3 genes. Nonparametric analysis of chromosome 20 inheritance data collected with the MODY1-linked marker D20S197 provides evidence for linkage to NIDDM with a P value of 0.005 in Caucasian sib pairs using affected sibpair (ASP) analyses. Non-parametric analysis of chromosome 12 inheritance data collected with the MODY3-linked markers D12S349 and D12S86 provides evidence for linkage to NIDDM with P values of 0.04 and 0.006, respectively, in Caucasian sib pairs using similar analyses. No evidence for linkage of MODY1 and MODY3 markers to NIDDM in African-American sib pairs was observed. In addition, no evidence for linkage to MODY2 (glucokinase-associated MODY) was observed with either study population. Results of multipoint maximum logarithm of odds (LOD) score analysis were consistent with the ASP results. A maximum LOD score of 1.48 was calculated for linkage to MODY1-linked loci and 1.45 to MODY3-linked loci in Caucasian sib pairs. Tabulation of allele sharing in affected sib pairs with D20S197 and D12S349 suggests that affected sibling pairs may inherit susceptibility genes simultaneously from chromosome 20 and chromosome 12. The results suggest that genes contributing to NIDDM in the general Caucasian population are located in the regions containing the MODY1 and MODY3 genes.

Phase I trial of a novel matrix metalloproteinase inhibitor batimastat (BB-94) in patients with advanced cancer

Degradation of basement membrane and extracellular matrix by matrix metalloproteinases (MMPs) is believed to be required for tumor invasion, tumor-induced angiogenesis and vascular invasion. A synthetic hydroxamate, batimastat (also known as BB-94), inhibits MMPs by binding the zinc ion in the active site of the MMP. Batimastat inhibits at least 50% of MMP activity at concentrations less than or equal to 10 ng/ml in vitro. Batimastat retarded ascites accumulation and increased survival in mice with human ovarian tumor xenografts. Acute and long-term toxicological studies revealed no major toxicity in animals. Batimastat is poorly soluble and was administered intraperitoneally (i.p.) as a suspension. Previous studies in patients with malignant ascites have shown no major toxicities at doses as high as 1350 mg/m2.

Zidovudine response relationships in early human immunodeficiency virus infection

OBJECTIVE

To examine predictors of magnitude of CD4+ response to treatment of human immunodeficiency virus (HIV) infection with zidovudine.

METHODS

This was a post hoc analysis of randomized placebo-controlled clinical trial in a multicenter trial, 1423 asymptomatic HIV-positive subjects with CD4+ cell counts less than 500 mm-3 were given 500 mg/day zidovudine, 1500 mg/day zidovudine, or placebo. The main outcome measure was change in the CD4+ cell counts over time.

RESULTS

This study suggests that earlier treatment with zidovudine results in a larger increment in the CD4+ cell count. In addition, the increment in CD4+ cell count is very long lived. However, drug exposure was not found to be a predictor of response to treatment in the dose range studied.

CONCLUSIONS

A parametric model of disease progression can be estimated with use of data collected in a conventionally designed study. These parametric models may provide insight into the optimal use of drugs. This model suggests that zidovudine does not change the underlying course of HIV infection but simply delays the time course. The model also suggests that the magnitude of this delay is larger when treatment is begun earlier in the course of the disease.

QT interval: a measure of drug action

Historically, QT prolongation, occurring with or without drug therapy, has been considered primarily as a clinical marker for risk of arrhythmia. However, as understanding of cardiac repolarization improves and ability to measure accurately small changes in QT interval increases, the QT interval will be used as a marker for drug action as well. In addition, QT prolongation may prove to be a valuable tool for detecting and quantifying risk of arrhythmia due to drugs. This has been emphasized recently by the experience with terfenadine. Use of the QT interval as a marker for toxicity and efficacy will require sensitive and specific methods that are currently being developed and validated. The current methodologies for detecting small changes in the QT interval and the significance of those changes are discussed.

Anticoagulation therapy advisor: a decision-support system for heparin therapy during ECMO

We present a case study describing our development of a mathematical model to control a clinical parameter in a patient--in this case, the degree of anticoagulation during extracorporeal membrane oxygenation (ECMO) support. During ECMO therapy, an anticoagulant agent (heparin) is administered to prevent thrombosis. Under- or over-coagulation can have grave consequences. To improve control of anticoagulation, we developed a pharmacokinetic-pharmacodynamic (PK-PD) model that predicts activated clotting times (ACT) using the NONMEM program. We then integrated this model into a decision-support system, and validated it with an independent data set. The population model had a mean absolute error of prediction for ACT values of 33.5 seconds, with a mean bias in estimation of -14.3 seconds. Individualization of model-parameter estimates using nonlinear regression improved the absolute error prediction to 25.5 seconds, and lowered the mean bias to -3.1 seconds. The PK-PD model is coupled with software for heuristic interpretation of model results to provide a complete environment for the management of anticoagulation.

[Severe hypopotassemia and rhabdomyolysis in a normotensive subject after use of a nasal spray containing 9-alpha-fluoroprednisolone]

We report the case of a 16-year-old boy who was admitted to our hospital for acute urinary retention, flaccid paralysis of the legs and arms and rhabdomyolysis due to a nasal spray containing 9-alpha-fluoroprednisolone. In our normotensive subject, rhabdomyolysis occurred after vigorous physical activity performed before the administration. The case emphasizes the need to avoid the use of 9-alpha-fluoroprednisolone considering its intense mineralocorticoid activity.