Biomedical subjects

William Frawley

Publications and source records attributed to William Frawley.

4 recordsLinked to original sources

PubMed2003

Myeloperoxidase promotor polymorphism and risk of hepatoblastoma.

Myeloperoxidase (MPO) is a major enzyme found in neutrophils. Oxidation by MPO produces free radicals that demonstrate genotoxic properties. A polymorphism (G to A) within the promotor region of the MPO gene reduces transcription and expression. This polymorphism is associated with a protective effect against some cancers in adults including lung cancer. The objective of our study was to investigate the effect of this MPO polymorphism on the risk of hepatoblastoma, the most common cancer of the liver in childhood. By using PCR-SSCP, we determined the genotype at this polymorphism in 48 cases of Caucasian children with hepatoblastoma and 180 normal controls. Genotypes were confirmed by a second method using Aci I restriction enzyme restriction. We found that A allele was associated with reduced risk of hepatoblastoma of 50% (OR, 0.51; 95%CI, 0.27-0.93) and G/A or A/A genotype reduced the risk by 56% (OR, 0.44; 95%CI, 0.21-0.90). Our data suggest that A allele is a protective factor with regard to the risk of hepatoblastoma, perhaps by altering genotoxic properties of xenobiotic substances which may act as carcinogens.

Alleles↗

PubMed2003

Tremor response to polarity, voltage, pulsewidth and frequency of thalamic stimulation.

BACKGROUND: Thalamic deep brain stimulation ameliorates essential and parkinsonian tremors refractory to medications. Stimulus voltage, polarity configuration, frequency, and pulsewidth can each be adjusted in order to optimize tremor control and maximize battery life. The relative impacts of these programmable variables have not previously been quantified. METHODS: The thalamus of 11 patients (bilaterally in 2) was studied 4 to 59 months postoperatively. The stimulator was inactivated and medications withheld for 12 hours, and optimal electrode contacts were selected. Stimulation followed at a range of voltages (0, 1, 2, 3, or 4 V), pulsewidths (60, 90, or 120 micros), and frequencies (130, 160, or 185 Hz) for both monopolar and bipolar configurations. Seventy-eight combinations of variables were programmed in random sequence. Postural and action tremors were measured with an electromagnetic tracker, tremor was subjectively graded, and side effects were noted. RESULTS: Voltage was consistently predictive of tremor response. Mean postural tremor amplitude in PD fell from 6.4 cm at 0 V to 2.6, 1.0, 0.3, and 0 cm at 1 through 4 V (bipolar configuration). The voltage response curve for essential tremor was flatter. The monopolar configuration was 10 to 25% more effective than bipolar. The longest pulsewidth tested was up to 30% more effective than the shortest, but frequency changes had little effect on tremor amplitude. Side effects occurred only with monopolar stimulation, and the only setting that was intolerable for the majority was 4 V, 120 micros, and 185 Hz. CONCLUSION: Bipolar deep brain stimulation at 90 micros, 130 Hz, adjusting the voltage up to 3 V, tends to be effective and well tolerated. Monopolar provides similar benefits for lower voltage, but side effects become common at 3 or 4 V.

Aged↗

PubMed2002

Decrease of core body temperature in mice by dehydroepiandrosterone.

Dietary dehydroepiandrosterone (DHEA) reduces food intake in mice, and this response is under genetic control. Moreover, both food restriction and DHEA can prevent or ameliorate certain diseases and mediate other biological effects. Mice fed DHEA (0.45% w/w of food) and mice pair-fed to these mice (food restricted) for 8 weeks were tested for changes in body temperature. DHEA was more efficient than food restriction alone in causing hypothermia. DHEA injected intraperitoneally also induced hypothermia that reached a nadir at 1 to 2 hr, and slowly recovered by 20 to 24 hr. This effect was dose dependent (0.5-50 mg). Each mouse strain tested (four) was susceptible to this effect, suggesting that the genetics differ for induction of hypophagia and induction of hypothermia. Because serotonin and dopamine can regulate (decrease) body temperature, we treated mice with haloperidol (dopamine receptor antagonist), 5,7-dihydroxytryptamine (serotonin production inhibitor), or ritanserin (serotonin receptor antagonist) prior to injection of DHEA. All of these agents increased rather than decreased the hypothermic effects of DHEA. DHEA metabolites that are proximate (5-androstene-3beta, 17beta-diol and androstenedione) or further downstream (estradiol-17beta) were much less effective than DHEA in inducing hypothermia. However, the DHEA analog, 16alpha-chloroepiandrosterone, was as active as DHEA. Thus, DHEA administered parentally seems to act directly on temperature-regulating sites in the body. These results suggest that DHEA induces hypothermia independent of its ability to cause food restriction, to affect serotonin or dopamine functions, or to act via its downstream steroid metabolites.

5,7-Dihydroxytryptamine↗

PubMedDate not supplied

Discourse changes in early Alzheimer disease, mild cognitive impairment, and normal aging.

The purpose of this study was to determine the sensitivity of discourse gist measures to the early cognitive-linguistic changes in Alzheimer disease (AD) and in the preclinical stages. Differences in discourse abilities were examined in 25 cognitively normal adults, 24 adults with mild probable AD, and 20 adults with mild cognitive impairment (MCI) at gist and detail levels of discourse processing. The authors found that gist and detail levels of discourse processing were significantly impaired in persons with AD and MCI as compared with normal control subjects. Gist-level discourse processing abilities showed minimal overlap between cognitively normal control subjects and those with mild AD. Moreover, the majority of the persons with MCI performed in the range of AD on gist measures. These findings indicate that discourse gist measures hold promise as a diagnostic complement to enhance early detection of AD. Further studies are needed to determine how early the discourse gist deficits arise in AD.

Aged↗