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Biomedical subjects

J McClay

Publications and source records attributed to J McClay.

9 recordsLinked to original sources
PubMed2002

The dopamine D4 receptor and the hyperactivity phenotype: a developmental-epidemiological study.

Attention-deficit hyperactivity disorder (ADHD) affects 2-6% of school-age children and is a precursor of behavioural problems in adolescence and adulthood. Underlying the categorical definition of ADHD are the quantitative traits of activity, impulsivity, and inattention which vary continuously in the population. Both ADHD and quantitative measures of hyperactivity are heritable, and influenced by multiple genes of small effect. Several studies have reported an association between clinically defined ADHD and the seven-repeat allele of a 48-bp tandem repeat polymorphism in the third exon of the dopamine D4 receptor gene (DRD4). We tested this association in a large, unselected birth cohort (n = 1037) using multiple measures of the hyperactivity phenotype taken at multiple assessment ages across 20 years. This longitudinal approach allowed us to ascertain whether or not DRD4 has a general effect on the diagnosed (n = 49) or continuously distributed hyperactivity phenotype, and related personality traits. We found no evidence to support this association.

Adolescent↗
PubMed2000

Allele association studies with SSR and SNP markers at known physical distances within a 1 Mb region embracing the ALDH2 locus in the Japanese, demonstrates linkage disequilibrium extending up to 400 kb.

There has been considerable recent debate concerning the distances over which levels of allelic association useful for genomic quantitative trait locus (QTL) scans can be detected. We have examined simple sequence repeat (SSR) polymorphisms and two single nucleotide polymorphisms (SNPs) in the region flanking the aldehyde dehydrogenase 2 locus, ALDH2, in populations of Japanese alcoholics and controls. These groups differ significantly in the allele frequencies for the functional SNP in exon XII of this gene located on chromosome 12. The results obtained with SSR markers complement recent investigations with SNPs over similar distances at the TCR alpha/delta locus. Significant allelic association with this marker could be detected for SSRs over distances up to 400 kb and over 37 kb for the SNP thereby extending the distance over which LD at this locus could be detected by an order of magnitude. Furthermore, as a proof of principle, we show that comparisons of allele frequency differences for the SSR markers in the case (alcoholics) and control populations would have detected the ALDH2 marker as a putative QTL. Extending the tests to include alleles at two or three flanking loci suggests that the power to detect QTLs through association can be enhanced significantly.

Alcohol Dehydrogenase↗
PubMed2000

Chloroma of the masseteric muscle.

Chloroma (leukemic infiltrate or granulocytic sarcoma) is a localized extramedullary mass of immature granulocytic cells. They are uncommon tumors that usually occur in patients with leukemia, mostly of the myeloid type. Involvement in the head and neck region is rare. Granulocytic sarcomas of the face, maxilla, paranasal sinuses, temporal bone, and pharynx have all been documented in the past. We present the first reported case of a granulocytic sarcoma involving the masseteric muscle in an 8-month-old white male diagnosed with acute myeloid leukemia (AML). The lesion resolved with chemotherapy but the patient subsequently died. This case reaffirms the importance of including chloroma in the differential diagnosis of lesions in patients with AML and the prognostic value they hold.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2000

Chasing behaviour genes into the next millennium.

Both linkage and association strategies are appropriate for the characterization of genes implicated in human behavioural dimensions and disorders. For the foreseeable future, association studies involving whole-genome scanning will combine strategies using both single-nucleotide and simple-sequence-repeat polymorphisms.

Genetic Linkage↗
PubMed1998

Aberrant second branchial cleft fistula.

Second branchial cleft cysts and sinuses rarely present diagnostic problems to the pediatric otolaryngologist as their course is usually predictable based on consistent embryologic development. However, we evaluated two fistula tracts that did not fit the classic description of second branchial tract fistulas. Upon radiographic and intraoperative evaluation, their eventual course ending in the tonsillar fossa was identified. Realizing the potential for aberrancy and using preoperative radiographic evaluation will assist the surgeon in the excision of these developmental anomalies with little risk to underlying neurovascular structures.

Branchioma↗
PubMed1987

Equilibrium binding of derivatives of the carcinogen, benzo(a)pyrene, to DNA. Thermodynamic analysis.

The physical binding of polycyclic aromatic hydrocarbon derivatives which are ultimate carcinogens to DNA may play a role in the formation of covalent DNA adducts by these compounds or in the detoxification of the compounds via DNA-catalyzed hydrolysis. Previous studies of DNA-binding interactions of derivatives of benzo(a)pyrene (BP) have been confined to low r values (r - ligands bound/base pair). We have now applied the Scatchard formalism (as modified to include neighbor exclusion) to the spectrophotometric determination of the binding of two derivatives of BP, trans - 9,10 - dihydroxydihydro - BP and 7r,8t - dihydroxy-9t,10t-oxy-7,8, 9,10-tetrahydro-BP, to double-stranded DNA at reasonably high r values. Exclusion parameters, binding constants, and thermodynamic parameters are all within the ranges found for other intercalants. Although these ligands are uncharged, the binding exhibits significant ionic strength dependence which can be rationalized (partially) by polyelectrolyte theory. Using the measured ionic strength dependence, a thermodynamic association constant, independent of ionic interactions, can be calculated which is very close to the calculated thermodynamic association constants for ethidium and proflavine.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗