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James M Fox

Publications and source records attributed to James M Fox.

12 recordsLinked to original sources
PubMed2006

Structure/function relationships of CCR8 agonists and antagonists. Amino-terminal extension of CCL1 by a single amino acid generates a partial agonist.

We describe here the interactions of CCR8 with its ligands using both CCR8 transfectants and a T-cell line expressing the receptor endogenously. Of the CCR8 agonists reported previously, only CCL1 and vMIP-I exhibited potency in assays of intracellular calcium flux, chemotaxis, and receptor internalization, this latter mechanism being dependent upon the expression of beta-arrestins 1 and 2 but independent of Galpha(i) signaling. NH(2)-terminal extension of the mature CCL1 sequence by a serine residue (Ser-CCL1) resulted in a partial agonist with a reduced affinity for CCR8, suggesting that the NH(2) terminus of the ligand plays a role in ligand binding to an intrahelical site. Attempts to identify key residues within this site revealed that the conserved glutamic acid residue in transmembrane helix 7, Glu-286, is crucial for trafficking of the receptor to the cell surface, while Asp-97 of transmembrane helix 2 is dispensable. CCL7 was found to inhibit both Ser-CCL1 and vMIP-I responses but not those of CCL1 itself. Similarly, vMIP-I responses were more than 2 orders of magnitude more sensitive to the specific CCR8 antagonist MC148 than those induced by CCL1, which is difficult to reconcile with the reported affinities for the receptor. Collectively, these data suggest that the CCR8 ligands are allotropic, binding to distinct sites within CCR8 and that the human immune system may have evolved to use CCL7 as a selective antagonist of viral chemokine activity at CCR8 but not those of the host ligand.

Aspartic Acid↗
PubMed2006

Predictions of CCR1 chemokine receptor structure and BX 471 antagonist binding followed by experimental validation.

A major challenge in the application of structure-based drug design methods to proteins belonging to the superfamily of G protein-coupled receptors (GPCRs) is the paucity of structural information (1). The 19 chemokine receptors, belonging to the Class A family of GPCRs, are important drug targets not only for autoimmune diseases like multiple sclerosis but also for the blockade of human immunodeficiency virus type 1 entry (2). Using the MembStruk computational method (3), we predicted the three-dimensional structure of the human CCR1 receptor. In addition, we predicted the binding site of the small molecule CCR1 antagonist BX 471, which is currently in Phase II clinical trials (4). Based on the predicted antagonist binding site we designed 17 point mutants of CCR1 to validate the predictions. Subsequent competitive ligand binding and chemotaxis experiments with these mutants gave an excellent correlation to these predictions. In particular, we find that Tyr-113 and Tyr-114 on transmembrane domain 3 and Ile-259 on transmembrane 6 contribute significantly to the binding of BX 471. Finally, we used the predicted and validated structure of CCR1 in a virtual screening validation of the Maybridge data base, seeded with selective CCR1 antagonists. The screen identified 63% of CCR1 antagonists in the top 5% of the hits. Our results indicate that rational drug design for GPCR targets is a feasible approach.

Animals↗
PubMed2004

Apoptosis and porcine reproductive and respiratory syndrome virus.

Despite numerous studies examining the possible induction of apoptosis in porcine reproductive and respiratory syndrome virus (PRRSV)-infected cells, it remains unclear if PRRSV infection results in direct apoptotic induction. There is clear evidence that apoptotic cells are present in tissues from PRRSV-infected pigs. However, many of these studies have failed to show that the apoptotic cells are infected with PRRSV. This has led some investigators to propose that "bystander" cells, not infected cells, become apoptotic during PRRSV infection by a yet undetermined mechanism. Studies examining the induction of the apoptotic gene expression response to PRRSV infection are needed to determine if PRRSV replication triggers an apoptotic response. We have utilized microarray and semi-quantitative reverse-transcription polymerase chain reaction (sqRT-PCR) to evaluate apoptotic gene expression in PRRSV-infected MARC-145 cells. Twenty-six apoptosis-related genes were examined during the first 24 h of infection and found to be unaltered, indicating that apoptotic induction was not occurring in PRRSV-infected cells. Additionally, using detection of free nucleosomal complexes, we examined cells for both apoptotic and necrotic death resulting from PRRSV infection at varying multiplicities of infection. This study indicates that PRRSV-infected MARC-145 cells undergo necrosis at a much higher level than apoptosis, and increases with virus levels used to infect the cells.

Animals↗
PubMed2004

Gene expression profiling of bovine macrophages in response to Escherichia coli O157:H7 lipopolysaccharide.

The aim of this study was to identify changes in bovine macrophage gene expression in response to treatment with Escherichia coli 0157:H7 lipopolysaccharide (LPS), utilizing a human gene microarray. Bovine cDNA from control and LPS-treated primary macrophages hybridized to greater than 5644 (79.8%) of the non-control gene targets on a commercially available microarray containing greater than 7075 targets (Incyte Genomics, St. Louis, MO). Of these target sequences, 44 were differentially expressed upon exposure to LPS, including 18 genes not previously reported to exist in cattle. These included a pentaxin-related gene, CASP8, TNF-induced genes, interferon-induced genes, and inhibitors of apoptosis. Using the human microarray, cDNA from bovine LPS-treated and control macrophages consistently hybridized to targets known to be expressed constitutively by macrophages, as expected given the predicted cDNA sequence homology. That this human system was accurately estimating levels of bovine transcripts was further verified by real-time quantitative reverse transcriptase polymerase chain reaction (RTQ-PCR) using bovine-specific primers. This first report of bovine-human cross-species expression profiling by microarray hybridization demonstrates the utility of this technique in bovine gene expression and discovery.

Animals↗
PubMed2004

Beta-2-microglobulin haplotypes in U.S. beef cattle and association with failure of passive transfer in newborn calves.

Failure of passive transfer (FPT) is a condition in which neonates do not acquire protective serum levels of maternal antibodies. A principal component of antibody transport is the neonatal receptor for the Fc portion of immunoglobulin, a heterodimer of a MHC-1 alpha-chain homolog ( FCGRT) and beta-2-microglobulin ( B2M). Previously, two FCGRT haplotypes were associated with differences in immunoglobulin G (IgG) passive transfer in cattle (Laegreid et al. (2002) Mamm Genome 13, 704-710). The present study had two objectives: first, to characterize the B2M haplotype structure in a diverse group of U.S. beef cattle, and second, to evaluate those haplotypes for association with either high or low serum IgG levels in newborn calves. Twelve single nucleotide polymorphisms (SNPs), assorted into eight haplotypes, were identified by sequencing regions of B2M exons II and IV in a multi-breed panel of 96 beef cattle. Calves homozygous for one of the eight haplotypes ( B2M 2,2) were at increased risk of FPT (odds ratio = 10.60, CI(95%) 2.07-54.24, p = 0.005). These results indicate that this haplotype is in linkage disequilibrium with genetic risk factors affecting passive transfer of IgG in beef calves, an important determinant of neonatal calf morbidity and mortality.

Animal Husbandry↗
PubMed2003

Congenital heart disease in adults: catheterization laboratory considerations.

Congenital heart defects are the most common birth defects and represent an increasing proportion of adolescent and adult patients followed by cardiologists. While many of these patients have undergone successful palliative or corrective surgery with excellent functional results, most of them still require careful follow-up. Further, even complex lesions may first be diagnosed in adolescence and adulthood. Therefore, cardiologists caring for adults need to become more familiar with these defects. Assessment of the patient with known or suspected congenital heart defects requires a careful history, physical examination, and noninvasive assessment. In addition, the catheterization laboratory remains a critical venue for diagnosis and, increasingly, therapy. Pressure measurements, oximetry, and angiography remain cornerstones of diagnosis in selected patients and a variety of interventional procedures have become viable therapeutic alternatives in both pre- and postoperative patients.

Adult↗
PubMed2003

Prion gene sequence variation within diverse groups of U.S. sheep, beef cattle, and deer.

Prions are proteins that play a central role in transmissible spongiform encephalopathies in a variety of mammals. Among the most notable prion disorders in ungulates are scrapie in sheep, bovine spongiform encephalopathy in cattle, and chronic wasting disease in deer. Single nucleotide polymorphisms in the sheep prion gene ( PRNP) have been correlated with susceptibility to natural scrapie in some populations. Similar correlations have not been reported in cattle or deer; however, characterization of PRNP nucleotide diversity in those species is incomplete. This report describes nucleotide sequence variation and frequency estimates for the PRNP locus within diverse groups of U.S. sheep, U.S. beef cattle, and free-ranging deer ( Odocoileus virginianus and O. hemionus from Wyoming). DNA segments corresponding to the complete prion coding sequence and a 596-bp portion of the PRNP promoter region were amplified and sequenced from DNA panels with 90 sheep, 96 cattle, and 94 deer. Each panel was designed to contain the most diverse germplasm available from their respective populations to facilitate polymorphism detection. Sequence comparisons identified a total of 86 polymorphisms. Previously unreported polymorphisms were identified in sheep (9), cattle (13), and deer (32). The number of individuals sampled within each population was sufficient to detect more than 95% of all alleles present at a frequency greater than 0.02. The estimation of PRNP allele and genotype frequencies within these diverse groups of sheep, cattle, and deer provides a framework for designing accurate genotype assays for use in genetic epidemiology, allele management, and disease control.

Amyloid↗
PubMed2003

Financial impact on emergency physicians for nonreimbursed care for the uninsured.

STUDY OBJECTIVE: The financial impact on emergency physicians' reimbursement for uninsured patient care has not been previously evaluated. We conducted this study to estimate the amount of emergency physicians' nonreimbursed care for uninsured patients in Michigan. METHODS: This retrospective observational study used a convenience sample of reimbursement information from 29 hospitals. Information collected included total uninsured visits, total uninsured collections, percentage of patients uninsured, and different levels of service provided to the uninsured. Data were collected for the first quarter of 2001 and yearly data extrapolated. Expected reimbursement was estimated by using Medicare and Medicaid fee schedules. The actual amount collected was subtracted from the calculated expected amount that should be collected, and this final amount was the estimate of nonreimbursed care for the uninsured. The state estimation used American Hospital Association total emergency department (ED) visits yearly and study sample rate of uninsured patients. RESULTS: The 29 hospitals represented 1,146,280 ED visits yearly (31% of the total state ED visits). The hospitals served an average uninsured population of 11.1% (95% confidence interval [CI] 10.7% to 13.3%), with average collection per uninsured patient of $16.50 (95% CI $12.87 to $20.12). According to Medicare and Medicaid fee schedules, the total nonreimbursement per uninsured patient was $77.15 (range $73.53 to $80.78) and $61.81 (range $58.19 to $65.44), respectively. The state estimate for nonreimbursed care to the uninsured was $31,717,000 per year (range $30,227,000 to $33,208,000) according to the Medicare fee schedule and $25,408,000 per year (range $23,921,000 to $26,902,000) according to Medicaid estimations. CONCLUSION: The amount of emergency physicians' nonreimbursed care of the uninsured is substantial.

Emergency Service, Hospital↗
PubMed2003

Effects of vessel geometry and catheter position on dose delivery in intracoronary brachytherapy.

In-stent restenosis is commonly observed in coronary arteries after intervention. Intravascular brachytherapy has been found effective in reducing the recurrence of restenosis after stent placement. Conventional dosing models for brachytherapy with beta (beta) radiation neglect vessel geometry as well as the position of the delivery catheter. This paper demonstrates in computer simulations on phantoms and on in vivo patient data that the estimated dose distribution varies substantially in curved vessels. In simulated phantoms of 50-mm length with a shape corresponding to a 60 degrees - 180 degrees segment of a respectively sized torus, the average dose in 2-mm depth was decreased by 2.70%-7.48% at the outer curvature and increased by 2.95%-9.70% at the inner curvature as compared with a straight phantom. In vivo data were represented in a geometrically correct three-dimensional model that was derived by fusion of intravascular ultrasound (IVUS) and biplane angiography. These data were compared with a simplified tubular model reflecting common assumptions of conventional dosing schemes. The simplified model yielded significantly lower estimates of the delivered radiation and the dose variability as compared with a geometrically correct model (p < 0.001). The estimated dose in ten vessel segments of eight patients was on average 8.76% lower at the lumen/plaque and 6.52% lower at the media/adventitia interfaces (simplified tubular model relative to geometrically correct model). The differences in dose estimates between the two models were significantly higher in the right coronary artery as compared with the left coronary artery (p < 0.001).

Arteries↗
PubMed2003

Are there disparities in emergency care for uninsured, medicaid, and privately insured patients?

OBJECTIVES: To determine if there are any differences in proportion of high-acuity care and low-acuity care provided to uninsured, Medicaid-insured, and privately insured emergency department (ED) patients. METHODS: This was a retrospective, observational study using physician level of service provided as a marker for acuity. The study used computerized billing data (2000-2001) from an urban, teaching, Level I trauma center with 75,000 visits per year. All uninsured and Medicaid patients (age groups: pediatric, <18 years; adult, 18-64 years) were compared by physician level of service billed to Blue Cross-Blue Shield (BCBS) patients and analyzed using chi-square. Low-acuity care was defined by CPT codes 99281 and 99282. High-acuity care was defined by CPT codes 99285 and 99291. RESULTS: There were 152,379 total ED visits, with 13.2% BCBS (5,273 pediatric, 14,951 adult), 29.6% Medicaid (20,578 pediatric, 24,511 adult), and 8.1% uninsured (1,879 pediatric, 10,405 adult) patients. The percent of pediatric BCBS, Medicaid, and uninsured patients receiving low-acuity care was 30%, 35.7%, and 35.8% (p < 0.001), respectively; and for high-acuity care, it was 7.8%, 6.1%, and 6.8% (p < 0.001), respectively. The proportion of adults within these groupings was 13.7%, 13.2%, and 17.9% (p < 0.001) for low-acuity care, and 28.5%, 22.9%, and 16.7% (p < 0.001) for high-acuity care, respectively. CONCLUSIONS: Whereas there were some statistically discerned differences between insurance groupings for proportionate receipt of low-acuity care and high-acuity care among both the pediatric and adult populations, the magnitude of most differences noted was not large, and may not reflect important differences in health care need or ED use based on insurance.

Adolescent↗