Biomedical subjects

P A Wood

Publications and source records attributed to P A Wood.

At least 19 recordsLinked to original sources

PubMed2006

Tunable dipolar magnetism in high-spin molecular clusters.

We report on the Fe17 high-spin molecular cluster and show that this system is an exemplification of nanostructured dipolar magnetism. Each Fe17 molecule, with spin S=35/2 and axial anisotropy as small as D approximately -0.02 K, is the magnetic unit that can be chemically arranged in different packing crystals while preserving both the spin ground state and anisotropy. For every configuration, molecular spins are correlated only by dipolar interactions. The ensuing interplay between dipolar energy and anisotropy gives rise to macroscopic behaviors ranging from superparamagnetism to long-range magnetic order at temperatures below 1 K.

Journal Article↗

PubMed2005

Circadian function in patients with advanced non-small-cell lung cancer.

This study aimed to evaluate whether patients with advanced non-small-cell lung cancer experience disrupted rest-activity daily rhythms, poor sleep quality, weakness, and maintain attributes that are linked to circadian function such as fatigue. This report describes the rest-activity patterns of 33 non-small-cell lung cancer patients who participated in a randomised clinical trial evaluating the benefits of melatonin. Data are reported on circadian function, health-related quality of life (QoL), subjective sleep quality, and anxiety/depression levels prior to randomisation and treatment. Actigraphy data, an objective measure of circadian function, demonstrated that patients' rest-activity circadian function differs significantly from control subjects. Our patients reported poor sleep quality and high levels of fatigue. Ferrans and Powers QoL Index instrument found a high level of dissatisfaction with health-related QoL. Data from the European Organization for Research and Treatment for Cancer reported poor capacity to fulfil the activities of daily living. Patients studied in the hospital during or near chemotherapy had significantly more abnormal circadian function than those studied in the ambulatory setting. Our data indicate that measurement of circadian sleep/activity dynamics should be accomplished in the outpatient/home setting for a minimum of 4-7 circadian cycles to assure that they are most representative of the patients' true condition. We conclude that the daily sleep/activity patterns of patients with advanced lung cancer are disturbed. These are accompanied by marked disruption of QoL and function. These data argue for investigating how much of this poor functioning and QoL are actually caused by this circadian disruption, and, whether behavioural, light-based, and or pharmacologic strategies to correct the circadian/sleep activity patterns can improve function and QoL.

Aged↗

PubMed2004

Effect of physician recommendation and patient adherence on rates of colorectal cancer testing.

This study explored: (1) patient characteristics associated with physician recommendation for colorectal cancer (CRC) screening and patient adherence to recommendation, and (2) the combined effect of recommendation and adherence on CRC testing, broadly defined. Data were from the 1999 MA BRFSS and a call-back survey of 869 BRFSS participants, age 50 and older. Logistic regression was used to identify correlates of recommendation, adherence, and testing. Patient-physician factors were positively associated with recommendation, adherence and testing. Inadequate health insurance was negatively associated with recommendation (OR = 0.45, 95% CI = 0.27-0.78) and testing (OR = 0.64, 95% CI = 0.38-1.1). Men were not more likely to be recommended (OR = 1.1, 95% CI = 0.78-1.5), but were more likely to adhere (OR = 1.9, 95% CI = 1.2-2.0) and to be tested (OR = 1.4, 95% CI = 1.0-1.9). There were gender differences in recommendation when considering health and risk factor measures. Research is needed to understand differences in recommendation and adherence. Greater encouragement and follow-through may be needed for groups less likely to adhere.

Aged↗

PubMed2001

Gestational, pathologic and biochemical differences between very long-chain acyl-CoA dehydrogenase deficiency and long-chain acyl-CoA dehydrogenase deficiency in the mouse.

Although many patients have been found to have very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency, none have been documented with long-chain acyl-CoA dehydrogenase (LCAD) deficiency. In order to understand the metabolic pathogenesis of long-chain fatty acid oxidation disorders, we generated mice with VLCAD deficiency (VLCAD(-/-)) and compared their pathologic and biochemical phenotypes of mice with LCAD deficiency (LCAD(-/-)) and wild-type mice. VLCAD(-/-) mice had milder fatty change in liver and heart. Dehydrogenation of various acyl-CoA substrates by liver, heart and skeletal muscle mitochondria differed among the three genotypes. The results for liver were most informative as VLCAD(-/-) mice had a reduction in activity toward palmitoyl-CoA and oleoyl-CoA (58 and 64% of wild-type, respectively), whereas LCAD(-/-) mice showed a more profoundly reduced activity toward these substrates (35 and 32% of wild-type, respectively), with a significant reduction of activity toward the branched chain substrate 2,6-dimethylheptanoyl-CoA. C(16) and C(18) acylcarnitines were elevated in bile, blood and serum of fasted VLCAD(-/-) mice, whereas abnormally elevated C(12) and C(14) acylcarnitines were prominent in LCAD(-/-) mice. Progeny with the combined LCAD(+/+)//VLCAD(+/-) genotype were over-represented in offspring from sires and dams heterozygous for both LCAD and VLCAD mutations. In contrast, no live mice with a compound LCAD(-/-)//VLCAD(-/-) genotype were detected.

Acyl-CoA Dehydrogenase, Long-Chain↗

PubMed2001

Lipoprotein secretion and triglyceride stores in the heart.

The genes for apolipoprotein B and microsomal triglyceride transfer protein are expressed in mouse and human heart tissue. Why the heart would express these "lipoprotein assembly" genes has been unclear. Here we demonstrate that the beating mouse heart actually secretes spherical lipoproteins. Moreover, increased cardiac production of lipoproteins (e.g., in mice that express a human apolipoprotein B transgene) was associated with increased triglyceride secretion from the heart and decreased stores of triglycerides within the heart. Increased cardiac production of lipoproteins also reduced the pathological accumulation of triglycerides that occurs in the hearts of mice lacking long-chain acyl coenzyme A dehydrogenase. In contrast, blocking heart lipoprotein secretion (e.g., in heart-specific microsomal triglyceride transfer protein knockout mice) increased cardiac triglyceride stores. Thus, heart lipoprotein secretion helps regulate cardiac triglyceride stores and may protect the heart from the detrimental effects of surplus lipids.

Animals↗

PubMed2001

Circadian expression of clock genes in human oral mucosa and skin: association with specific cell-cycle phases.

We studied the relative RNA expression of clock genes throughout one 24-hour period in biopsies obtained from the oral mucosa and skin from eight healthy diurnally active male study participants. We found that the human clock genes hClock, hTim, hPer1, hCry1, and hBmal1 are expressed in oral mucosa and skin, with a circadian profile consistent with that found in the suprachiasmatic nuclei and the peripheral tissues of rodents. hPer1, hCry1, and hBmal1 have a rhythmic expression, peaking early in the morning, in late afternoon, and at night, respectively, whereas hClock and hTim are not rhythmic. This is the first human study to show a circadian profile of expression for all five clock genes as documented in rodents, suggesting their functional importance in man. In concurrent oral mucosa biopsies, thymidylate synthase enzyme activity, a marker for DNA synthesis, had a circadian variation with peak activity in early afternoon, coinciding with the timing of S phase in our previous study on cell-cycle timing in human oral mucosa. The major peak in hPer1 expression occurs at the same time of day as the peak in G(1) phase in oral mucosa, suggesting a possible link between the circadian clock and the mammalian cell cycle.

ARNTL Transcription Factors↗

PubMed2001

Childhood and adolescent onset conduct disorder: a test of the developmental taxonomy.

Hypotheses generated by a developmental taxonomy that distinguishes between childhood and adolescent onset conduct disorders were tested. Hypotheses predicted that (1) individual and familial factors would be more strongly related to childhood onset conduct disorder, whereas ethnic minority status and exposure to deviant peers would be more strongly related to adolescent onset conduct disorder and (2) individuals with childhood onset disorder would be more likely to commit violent and victim oriented offenses than individuals with adolescent onset conduct disorder. The first hypothesis was strongly supported and the second hypothesis was partially supported. Implications for early identification of youth at risk for chronic offending are discussed.

Adolescent↗

PubMed2001

Prevalence of psychiatric disorders in youths across five sectors of care.

OBJECTIVE: To examine the prevalence of psychiatric disorders among youths from the following five public sectors of care: alcohol and drug services (AD), child welfare (CW), juvenile justice (JJ), mental health (MH), and public school services for youths with serious emotional disturbance (SED) in San Diego, California. METHOD: The Diagnostic Interview Schedule for Children was administered between October 1997 and January 1999 for 1,618 randomly selected youths aged 6-18 years who were active in at least one of the five sectors. RESULTS: Fifty-four percent of the participants met criteria for at least one study disorder. Attention-deficit/hyperactivity disorder (ADHD) and disruptive behavior disorders (50%) were much more common than anxiety (10%) or mood (7%) disorders. Youths who were active in the MH and SED sectors were more likely than those not in these sectors to meet criteria for a disorder; youths in the CW sector were least likely. CONCLUSIONS: Rates of psychiatric disorders, specifically ADHD and disruptive behavior disorders, are extremely high for youths in public sectors of care. Rates are generally higher in sectors designed to serve youths with psychiatric needs, but the prevalence of disorders was also high in sectors not specifically designed for this need (e.g., CW and JJ).

Adolescent↗

PubMed2001

Prevalence of adolescent substance use disorders across five sectors of care.

OBJECTIVE: To examine the prevalence of substance use disorders (SUDs) among adolescents who received services in one or more of the following public sectors of care: alcohol and drug (AD), juvenile justice (JJ), mental health (MH), public school-based services for youths with serious emotional disturbance (SED), and child welfare (CW), in relation to age, gender, and service sector affiliation. METHODS: Participants included 1,036 adolescents aged 13 to 18 years, randomly sampled from all youths who were active in at least one of the above five sectors of care (N = 12,662) in San Diego County California. SUDs were assessed through structured diagnostic interviews conducted from October 1997 through January 1999. RESULTS: SUDs were found for youths in all sectors of care, with lifetime rates of 82.6% in AD, 62.1% in JJ, 40.8% in MH, 23.6% in SED, and 19.2% in CW. Rates of SUDs were significantly higher among older youths and males. Sector differences held even when accounting for the effects of age and gender. CONCLUSIONS: SUDs are highly prevalent among youths receiving care in the AD service sector as well as other sectors, particularly JJ and MH. These findings have implications for assessment, treatment, and service coordination for youths with SUDs in diverse sectors of public care.

Adolescent↗

PubMed2000

Circadian organization of thymidylate synthase activity in normal tissues: a possible basis for 5-fluorouracil chronotherapeutic advantage.

Fluoropyrimidines induce cytotoxicity, in part, by inhibiting the proliferation-coordinated enzyme thymidylate synthase (TS), which is essential for DNA synthesis. Tumor TS levels are clinically predictive of post-surgical tumor recurrence and of response to fluoropyrimidine chemotherapy. Fluoropyrimidine drug toxicity and efficacy each vary reproducibly in humans and animals, depending upon their circadian timing. In vivo, normal tissues and some tumor tissues exhibit circadian coordination of cellular proliferation. We therefore asked whether TS activity is coordinated rhythmically throughout the day in the normal proliferative tissues most damaged by fluoropyrimidine drugs. To assess tissue and time of day TS activity differences, we harvested normal tissues from female mice living on a 12:12 hr light:dark schedule at each of 6 different equispaced times throughout a 24 hr cycle and measured TS catalytic activity. We observed up to 10-fold differences in vivo in TS activity among different normal tissue types, roughly paralleling their proliferative state and relative fluoropyrimidine sensitivity. In normal tissues most damaged by fluoropyrimidines (bone marrow, small intestinal mucosa and oral mucosa/tongue), TS activity varies up to 2-fold throughout each day. In bone marrow, the circadian pattern of TS activity parallels the circadian rhythm in proliferation in this tissue. This circadian organization of TS, one of the primary fluoropyrimidine targets in normal tissues, probably contributes in vivo to the time of day differences in the toxic-therapeutic ratio of circadian-timed fluoropyrimidine drug therapy.

Animals↗

PubMed2000

Phenotype assessment: are you missing something?

BACKGROUND AND PURPOSE: Phenotype assessment of genetically modified rodents is an essential component of animal model development and their eventual use. Described here is a paradigm to consider as we collectively pursue phenotype assessment of the constantly increasing number of genetically modified rodent models, as well as those with spontaneously occurring mutations. METHODS: Review of past experiences and the literature provides useful examples to illustrate the principles described. CONCLUSION: A practical approach to phenotype assessment can be divided into a primary level of assessment to find abnormalities, and a secondary level of more specialized assessment to quantify and evaluate the abnormalities detected. There are many subtle, but important phenotypic characteristics that can be markedly affected by the background genetics and environment of the animal being assessed.

Acyl-CoA Dehydrogenase↗

PubMed2000

Transgenic studies of fatty acid oxidation gene expression in nonobese diabetic mice.

Type 1 diabetes mellitus is a devastating disorder affecting both glucose and lipid metabolism. Using the nonobese diabetic (NOD) mouse model, we found that diabetic mice had a liver-specific increase in steady state mRNA levels for enzymes involved in oxidation of fatty acids. Increased mRNA abundance was observed in very long-chain acyl-CoA dehydrogenase, long-chain acyl-CoA dehydrogenase (LCAD), medium-chain acyl-CoA dehydrogenase (MCAD), carnitine palmitoyltransferase I (CPT-1a), and the gluconeogenic enzyme phosphoenolpyruvate carboxykinase, whereas short-chain acyl-CoA dehydrogenase mRNA remained unchanged. In contrast, minimal elevations in LCAD and CPT-1a mRNA were observed in hearts of diabetic mice with no significant differences found for the other enzymes. We developed NOD mice with transgenes containing regulatory elements of human MCAD gene controlling a reporter gene to determine if the increase in MCAD gene expression occurred via the well-characterized nuclear receptor response element (NRRE-1). These results demonstrated that the transgene containing the NRRE-1 and adjacent 5' sequences had elevated liver expression in diabetic mice compared with prediabetic or normal control mice. Surprisingly, the transgene that contains NRRE-1 with adjacent 3' sequences and the transgene with the NRRE-1 deleted showed minimal response to the fulminant diabetic condition.Collectively, these results indicate that in type 1 diabetes there exists an excessive and liver-specific activation of fatty acid oxidation gene expression. Using human MCAD as a prototype gene, we have shown that this increased expression is mediated at the transcriptional level but does not occur via the well-characterized NRRE-1 site responsible for baseline expression in normal mice.

Acyl-CoA Dehydrogenase, Long-Chain↗

PubMed1999

Lessons learned from the mouse model of short-chain acyl-CoA dehydrogenase deficiency.

The SCAD deficient mouse model has been useful to investigate mechanisms of deficient fatty acid oxidation disease in human patients. This mouse model has been thoroughly characterized and is readily available from the Jackson Laboratory. Using the new technologies of gene-knockout mouse modeling, we envisage developing additional members of the acyl-CoA dehydrogenase family of enzyme deficiencies in mice and furthering our understanding of fatty acid metabolism in health and disease.

Acyl-CoA Dehydrogenase↗

PubMed1999

Defects in mitochondrial beta-oxidation of fatty acids.

Mitochondrial beta-oxidation of fatty acids generates energy by direct electron transfer at the dehydrogenase steps along with the ultimate product of acetyl-coenzyme A that can be further oxidized for ATP synthesis, or conversion to ketone bodies. This review describes the human inborn errors of this pathway and recent results concerning the development and use of mouse models of these inherited enzyme deficiencies.

Acyl-CoA Dehydrogenase↗

PubMed1998

Targeted disruption of mouse long-chain acyl-CoA dehydrogenase gene reveals crucial roles for fatty acid oxidation.

Abnormalities of fatty acid metabolism are recognized to play a significant role in human disease, but the mechanisms remain poorly understood. Long-chain acyl-CoA dehydrogenase (LCAD) catalyzes the initial step in mitochondrial fatty acid oxidation (FAO). We produced a mouse model of LCAD deficiency with severely impaired FAO. Matings between LCAD +/- mice yielded an abnormally low number of LCAD +/- and -/- offspring, indicating frequent gestational loss. LCAD -/- mice that reached birth appeared normal, but had severely reduced fasting tolerance with hepatic and cardiac lipidosis, hypoglycemia, elevated serum free fatty acids, and nonketotic dicarboxylic aciduria. Approximately 10% of adult LCAD -/- males developed cardiomyopathy, and sudden death was observed in 4 of 75 LCAD -/- mice. These results demonstrate the crucial roles of mitochondrial FAO and LCAD in vivo.

Acyl-CoA Dehydrogenase, Long-Chain↗

PubMed1998

Abnormal nonshivering thermogenesis in mice with inherited defects of fatty acid oxidation.

When placed in the cold (4 degreesC), BALB/cByJ mice of both genders rapidly lose body temperature as compared with the control strain, C57BL/6J. This sensitivity to cold resembles that previously described for mice with a defect in nonshivering thermogenesis due to the targeted inactivation of the brown adipocyte-specific mitochondrial uncoupling protein gene, Ucp1. Genetic mapping of the trait placed the gene on chromosome 5 near Acads, a gene encoding the short chain acyl CoA dehydrogenase, which is mutated in BALB/cByJ mice. The analysis of candidate genes in the region indicated a defect only in the expression of Acads. Confirmation of the importance of fatty acid oxidation to thermogenesis came from our finding that mice carrying the targeted inactivation of the long chain acyl CoA dehydrogenase gene (Acadl) are also sensitive to the cold. Both of these mutations attenuate the induction of genes normally responsive to adrenergic signaling in brown adipocytes. These results suggest that the action of fatty acids as regulators of gene expression has been perturbed in the mutant mice. From a clinical perspective, it is important to determine whether defects in thermogenesis may be a phenotype in human neonates with inherited deficiencies in fatty acid beta-oxidation.

Acyl-CoA Dehydrogenase↗

PubMed1998

Studies of arginine metabolism and salt sensitivity in the Dahl/Rapp rat models of hypertension.

Previous studies by our group demonstrated a striking relationship among arginine, nitric oxide production, and salt-sensitive hypertension in the Dahl/Rapp rat. We hypothesized that enzymes of the urea cycle may be involved in this process. We specifically examined the activities of liver and kidney argininosuccinate synthetase (AS), because this enzyme is an essential step of arginine synthesis and a likely control point. We found that salt-sensitive (S) rats on a high-salt diet developed hypertension without change in plasma concentrations of arginine, citrulline, and ornithine. Baseline plasma concentrations of these amino acids were the same in rats of all three genotypes: Sprague-Dawley (SD), S, and salt-resistant (R) Dahl/Rapp rats. In contrast, R rats on the high-salt diet remained normotensive coincidentally with elevated levels of arginine and ornithine, as compared to normotensive R rats on low-salt diet with no changes in amino acid concentrations. S rats on high-salt diet became hypertensive coincidentally with no changes in amino acid concentrations. None of the rat groups had significantly different activity of liver of kidney AS coincidental with the salt in the diet and the changes in amino acid concentrations found in the R rats. Thus, given the lack of alteration in plasma concentrations of the urea cycle amino acids of arginine, citrulline, and ornithine in S rats, genes of the urea cycle/arginine synthesis are unlikely to be involved in salt-sensitive hypertension in this strain. The mechanism of increased plasma arginine and ornithine concentrations in R rats was not determined, but was not related to AS activity.

Alanine↗

PubMed1998

Structural characterization of the mouse long-chain acyl-CoA dehydrogenase gene and 5' regulatory region.

Long-chain acyl-CoA dehydrogenase (LCAD) is one of four enzymes involved in the initial step of mitochondrial beta-oxidation of straight-chain fatty acids. It is a member of the acyl-CoA dehydrogenase (Acad or ACAD) gene family of enzymes, which also includes very-long-chain (VLCAD), medium-chain (MCAD), and short-chain (SCAD) acyl-CoA dehydrogenases. These enzymes all have similar activity but differ only in the chain length specificity for their substrate. Mitochondrial beta-oxidation provides an important source of energy especially during times of fasting. In order to understand the role of LCAD in this pathway, we have cloned and characterized the entire mouse (Mus musculus) gene encoding LCAD (Acadl). Acadl is a single-copy, nuclear encoded gene approximately 35 kb in size. We have sequenced the entire coding region, all intron/exon boundaries, 1.7 kb of its 5' regulatory region, and mapped the transcription start site. The gene contains 11 coding exons ranging in size from 67 bp to 275 bp, interrupted by 10 introns ranging in size from 1.0 kb to 6.6 kb in size. The Acadl 5' regulatory region, like other members of the Acad family, lacks a TATA or CAAT box and is GC rich. This region does contain multiple, putative cis-acting DNA elements recognized by either SP1 or members of the steroid-thyroid family of nuclear receptors, which has been shown with other members of the ACAD gene family to be important in regulated expression. The characterization of the mouse Acadl gene will allow further study of LCAD in an in vivo model, and how its expression may be coordinated with other members of the Acad gene family.

Acyl-CoA Dehydrogenase, Long-Chain↗