PubMed Health⌕ Search

Biomedical subjects

Craig Williams

Publications and source records attributed to Craig Williams.

18 recordsLinked to original sources
PubMed2006

Reliability of 31P-magnetic resonance spectroscopy during an exhaustive incremental exercise test in children.

This study examined the reliability of (31)P-magnetic resonance spectroscopy (MRS) to measure parameters of muscle metabolic function in children. On separate days, 14 children (7 boys and 7 girls) completed three knee-extensor incremental tests to exhaustion inside a whole-body scanner (1.5 T, Phillips). The dynamic changes in the ratio of inorganic phosphate to phosphocreatine (Pi/PCr) and intracellular muscle pH were resolved every 30 s. Using plots of Pi/PCr and pH against power output (W), intracellular thresholds (ITs) for each variable were determined using both subjective and objective procedures. The IT(Pi/PCr) and IT(pH) were observed subjectively in 93 and 81% of their respective plots, whereas the objective method identified the IT(Pi/PCr) in 88% of the plots. The IT(pH) was undetectable using the objective method. End exercise (END) END(Pi/PCr), END(pH), IT(Pi/PCr) and IT(pH) were examined using typical error statistics expressed as a % coefficient of variation (CV) across all three exercise tests. The CVs for the power output at the subjectively determined IT(Pi/PCr) and IT(pH) were 10.6 and 10.3%, respectively. Objective identification of the IT(Pi/PCr) had a CV of 16.3%. CVs for END(pH) and END(Pi/PCr) were 0.9 and 50.0%, respectively. MRS provides a valuable window into metabolic changes during exercise in children. During knee-extensor exercise to exhaustion, END(pH) and the subjectively determined IT(Pi/PCr) and IT(pH) demonstrate good reliability and thus stable measures for the future study of developmental metabolism. However, the objectively determined IT(Pi/PCr) and END(Pi/PCr) displayed poor reliability.

Child↗
PubMed2006

Ovarian volume: determinants and associations with cancer among postmenopausal women.

Clinical studies have reported associations between ovarian stromal hyperplasia and the diagnosis of hormonally related tumors such as endometrial cancer. To assess the hypothesis that characteristics of benign ovaries among postmenopausal women are related to risk for breast, endometrial, and colon cancer, we analyzed systematically collected transvaginal ultrasound data for participants enrolled in the screening arm of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Among women without cancer, median ovarian volume declined with age from 1.25 cm3 for women between ages 55 and 59 years to 1.0 cm3 for those between ages 65 and 69 years. African American and Caucasian women had larger median ovarian volumes than Asians. Larger ovarian volume was also associated with the highest quartiles of height and weight and ever having smoked. After adjusting for race, age, parity, body mass, smoking, and hormone use, women with median ovarian volumes >or=3.0 cm3 were at increased risk for breast cancer [odds ratio (OR), 1.42; 95% confidence interval (95% CI), 1.11-1.70], endometrial cancer (OR, 1.97; 95% CI, 1.12-3.48), and colon cancer (OR, 2.00; 95% CI, 1.25-3.21). Significant trends of risk with increasing volume were found only for breast and endometrial cancers. We conclude that large ovaries among postmenopausal women may represent a marker of risk for hormonally related tumors. Confirmation of these findings in future studies, including analyses of serum hormone levels and tissues, may provide insights into hormonal carcinogenesis among older women.

Aged↗
PubMed2006

Discovery of a widespread infestation of Aedes albopictus in the Torres Strait, Australia.

Aedes albopictus is a container-breeding Stegomyia mosquito that has dispersed widely from its origins in Southeast Asia. Because Ae. albopictus is a known dengue vector and a potential vector of a variety of arboviruses and it can tolerate cooler climates than Aedes aegypti, Australian quarantine and health authorities have strategies to detect and eliminate it from international ports. Following the detection of 42 adult Ae. albopictus in BG-Sentinel traps set on Yorke island in the Torres Strait of Australia in April 2005, extensive surveys were conducted to determine the distribution of Ae. albopictus in the Torres Strait and adjoining Cape York Peninsula. A total of 17 islands and the northern peninsula area of Cape York Peninsula were surveyed by collection of larvae and pupae from flooded containers and human bait collections of adult mosquitoes with aspirators and sweep nets. Aedes albopictus was detected on 10 islands and comprised 100% of the day-biting container-breeding mosquitoes on Yorke and Stephens Islands. No Ae. albopictus were detected in the mainland sites on Cape York. Retrospective genetic analysis of larvae collected in April 2004 and April 2005 on Yorke Island indicated that Ae. albopictus was present in low densities in 2004 and that there were 3 genetically distinct mitochondrial haplotypes on Yorke Island in April 2005. Additionally, on Yorke Island there is evidence that Ae. albopictus is displacing Aedes scutellaris.

Aedes↗
PubMed2005

Serum zinc correlates with parent- and teacher- rated inattention in children with attention-deficit/hyperactivity disorder.

OBJECTIVE: The aim of this study was to explore the relationship of zinc nutrition to the severity of attention-deficit/hyperactivity disorder (ADHD) symptoms in a middle-class American sample with well-diagnosed ADHD. Previous reports of zinc in ADHD, including two positive clinical trials of supplementation, have come mainly from countries and cultures with different diets and/or socioeconomic realities. METHOD: Children 5-10 years of age with DISC- and clinician-diagnosed ADHD had serum zinc determinations and parent and teacher ratings of ADHD symptoms. Zinc levels were correlated (Pearson's and multiple regression) with ADHD symptom ratings. RESULTS: Forty-eight children (37 boys, 11 girls; 33 combined type, 15 inattentive) had serum zinc levels with a median/mode at the lowest 30% of the laboratory reference range; 44 children also had parent/teacher ratings. Serum magnesium levels were normal. Nutritional intake by a parent-answered food frequency questionnaire was unremarkable. Serum zinc correlated at r = -0.45 (p = 0.004) with parent-teacher-rated inattention, even after controlling for gender, age, income, and diagnostic subtype, but only at r = -0.20 (p = 0.22) with CPT omission errors. In contrast, correlation with parent-teacher-rated hyperactivity-impulsivity was nonsignificant in the opposite direction. CONCLUSION: These findings add to accumulating evidence for a possible role of zinc in ADHD, even for middle-class Americans, and, for the first time, suggest a special relationship to inattentive symptoms. They do not establish either that zinc deficiency causes ADHD nor that ADHD should be treated with zinc. Hypothesis-testing clinical trials are needed.

Attention Deficit Disorder with Hyperactivity↗
PubMed2005

Blood flow to the metatarsal head after chevron bunionectomy.

BACKGROUND: Avascular necrosis (AVN) of the metatarsal head is a known, but infrequent, complication of a chevron bunionectomy. An increased incidence of AVN has been reported with the addition of an adductor tenotomy and lateral release. The purpose of this study was to document the vascular insult to the metatarsal head during a chevron bunionectomy with adductor tenotomy and lateral release through direct blood flow measurements during the procedure. METHODS: A prospective study of 20 patients was performed. A chevron bunionectomy was performed under regional anesthesia without tourniquet control by two surgeons. Blood flow recordings were documented during key portions of the procedure: baseline, medial capsulotomy, adductor tenotomy and lateral release, and chevron osteotomy. The Periflux PF3 laser Doppler probe (Perimed, Inc., North Royalton, OH) was used to record blood flow. Mauchly's test of Sphericity and a pairwise comparison were performed with significance defined as p < 0.05. All patients had radiographs 3 months postoperatively to assess AVN. RESULTS: There was a statistically significant decrease in blood flow to the metatarsal head at each portion of the procedure. The greatest insult occurred with the medial capsulotomy (45% decrease). The lateral release and adductor tenotomy caused a 13% decrease and the chevron osteotomy caused a 13% decrease, totaling 71% decrease from the baseline. There was no evidence of AVN at 3 months, and all patients had radiographic evidence of union without recurrence or over-correction. CONCLUSION: The addition of the adductor tenotomy with lateral release often is crucial to obtain the desired correction and avoid the complication of recurrence. The disruption of microvascular blood flow to the metatarsal head after a chevron bunionectomy with adductor tenotomy and lateral release was not complete, totaling 71% in the study population. The greatest insult occurred with the medial capsulotomy. There were no occurrences of AVN. Despite the fear of AVN, this study demonstrated that an adductor tenotomy and lateral release could be done safely completed with a chevron bunionectomy.

Adult↗
PubMed2004

DNA replication licensing in somatic and germ cells.

The DNA replication (or origin) licensing system ensures precise duplication of the genome in each cell cycle and is a powerful regulator of cell proliferation in metazoa. Studies in yeast, Drosophila melanogaster and Xenopus laevis have characterised the molecular machinery that constitutes the licensing system, but it remains to be determined how this important evolutionary conserved pathway is regulated in Homo sapiens. We have investigated regulation of the origin licensing factors Cdc6, Cdt1, Mcm2 and Geminin in human somatic and germ cells. Cdc6 and Cdt1 play an essential role in DNA replication initiation by loading the Mcm2-7 complex, which is required for unwinding the DNA helix, onto chromosomal origins. Geminin is a repressor of origin licensing that blocks Mcm2-7 loading onto origins. Our studies demonstrate that Cdc6, Cdt1 and Mcm2 play a central role in coordinating growth during the proliferation-differentiation switch in somatic self-renewing systems and that Cdc6 expression is rate-limiting for acquisition of replication competence in primary oocytes. In striking contrast, we show that proliferation control during male gametogenesis is not linked to Cdc6 or Mcm2, but appears to be coordinated by the negative regulator Geminin with Cdt1 becoming rate-limiting in late prophase. Our data demonstrate a striking sexual dimorphism in the mechanisms repressing origin licensing and preventing untimely DNA synthesis during meiosis I, implicating a pivotal role for Geminin in maintaining integrity of the male germline genome.

Alternative Splicing↗
PubMed2003

Helicobacter pylori: a microbiologist's view.

Helicobacter pylori infection is known to cause a number of gastrointestinal diseases. From the standpoint of a microbiologist there are several important facets to this organism, which include the nature of the organism, it's diagnosis and the effectiveness of eradication therapy.

Bacteriological Techniques↗
PubMed2003

Ethylene glycol intoxication: case report and pharmacokinetic perspectives.

A 42-year-old man was brought to the emergency department with ethylene glycol intoxication. He was hemodynamically stable and had normal renal function. His serum ethylene glycol concentration was 284 mg/dl approximately 1 hour after ethylene glycol consumption. The patient was treated with fomepizole and forced diuresis. Elimination of ethylene glycol in this patient followed first-order pharmacokinetics. Elimination pharmacokinetics in this patient were compared with that in a patient who received fomepizole and hemodialysis. Fomepizole monotherapy can be given in patients without renal failure or metabolic acidosis even with serum ethylene glycol concentrations greater than 50 mg/dl. However, cost estimates based on this case suggest that if the patient is treated adequately with a single hemodialysis session and 24-hour hospitalization, then fomepizole monotherapy may be more expensive than the combination regimen of fomepizole and hemodialysis.

Adult↗
PubMed2003

Incremental exercise, plasma concentrations of catecholamines, reaction time, and motor time during performance of a noncompatible choice response time task.

The primary purpose was to examine the effect of incremental exercise on a noncompatible response time task. Participants (N=9) undertook a 4-choice noncompatible response time task under 3 conditions, following rest and during exercise at 70% and 100% of their maximum power output. Reaction and movement times were the dependent variables. Maximum power output had been previously established on an incremental test to exhaustion. A repeated-measures multivariate analysis of variance yielded a significant effect of exercise intensity on the task, observation of the separate univariate repeated-measures analyses of variance showed that only movement time was significantly affected. Post hoc Tukey tests indicated movement time during maximal intensity exercise was significantly faster than in the other two conditions. The secondary purpose of the study was to assess whether increases in plasma concentrations of adrenaline and nor-adrenaline during exercise and power output would act as predictor variables of reaction and movement times during exercise. Catecholamine concentrations were based on venous blood samples taken during the maximum power output test. None of the variables were significant predictors of reaction time. Only power output was a significant predictor of movement time (R2 = .24). There was little support for the notion that peripheral concentrations of catecholamines directly induce a central nervous system response.

Adult↗
PubMed2002

Haemophilus influenzae in acute exacerbations of chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is a common progressive respiratory disease that is associated with infective exacerbations that lead to worsening of symptoms. Many organisms are thought to trigger infective exacerbations, but Haemophilus influenzae is the most commonly isolated bacterium. The role of H. influenzae in infective exacerbations remains uncertain, mainly because the organism chronically colonises patients whose clinical condition is stable. H. influenzae may also comprise part of the normal nasopharyngeal flora in man, making the interpretation of positive cultures difficult in some cases.

Acute Disease↗
PubMed2002

Enhancing foodborne disease surveillance across Australia in 2001: the OzFoodNet Working Group.

In 2000, the OzFoodNet network was established to enhance surveillance of foodborne diseases across Australia. OzFoodNet consists of 7 sites and covers 68 per cent of Australia's population. During 2001, sites reported 15,815 cases of campylobacteriosis, 6,607 cases of salmonellosis, 326 cases of shigellosis, 71 cases of yersiniosis, 61 cases of listeriosis, 47 cases of shiga-toxin producing E. coli and 5 cases of haemolytic uraemic syndrome. Sites reported 86 foodborne outbreaks affecting 1,768 people, of whom 4.0 per cent (70/1,768) were hospitalised and one person died. There was a wide range of foods implicated in these outbreaks and the most common agent was S. Typhimurium. Sites reported two international outbreaks; one of multi-drug resistant S. Typhimurium Definitive Type 104 due to helva imported from Turkey, and one of S. Stanley associated with dried peanuts from China. The National Centre for Epidemiology and Population Health conducted a national survey of gastroenteritis. Preliminary data from interviews of 2,417 people suggests that the incidence of foodborne illness is significantly higher than previously thought. OzFoodNet initiated case control studies into risk factors for Campylobacter, Salmonella, Listeria, and shiga-toxin producing E. coli. OzFoodNet developed a foodborne disease outbreak register for Australia; established a network of laboratories to type Campylobacter; prepared a survey of pathology laboratories; reviewed Australian data on listeriosis; and assessed the usefulness of sentinel surveillance for gastroenteritis. This program of enhanced surveillance has demonstrated its capacity to nationally investigate and determine the causes of foodborne disease.

Adolescent↗