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Biomedical subjects

J Williams

Publications and source records attributed to J Williams.

At least 73 records · Page 4Linked to original sources
PubMed2004

Control of myocardial oxygen consumption in transgenic mice overexpressing vascular eNOS.

Our objective was to investigate the potential role of selective endothelial nitric oxide (NO) synthase (eNOS) overexpression in coronary blood vessels in the control of myocardial oxygen consumption (MVO2). Transgenic (Tg) eNOS-overexpressing mice (eNOS Tg) (n=22) and wild-type (WT) mice (n=24) were studied. Western blot analysis indicated greater than sixfold increase of eNOS in cardiac tissue. Echocardiography in awake mice indicated no difference in cardiac function between WT and eNOS Tg; however, systolic pressure in eNOS Tg mice decreased significantly (126 +/- 2.3 to 109 +/- 2.3 mmHg; P <0.05), whereas heart rate (HR) was not different. Total peripheral resistance (TPR) was also decreased (9.8 +/- 0.8 to 7.6 +/- 0.4 4 mmHg.ml(-1).min; P <0.05) in eNOS Tg. Furthermore, female eNOS Tg mice showed even lower TPR (7.2 +/- 0.4 mmHg.ml(-1).min) compared with male eNOS mice (8.6 +/- 0.5, mmHg.ml.min(-1); P <0.05). Left ventricular slices were isolated from WT and eNOS Tg mice. With the use of a Clark-type oxygen electrode in an airtight bath, MVO2 was determined as the percent decrease during increasing doses (10(-10) to 10(-4) mol/l) of bradykinin (BK), carbachol (CCh), forskolin (10(-12) to 10(-6) mol/l), or S-nitroso-N-acetyl penicillamine (SNAP; 10(-7) to 10(-4) mol/l). Baseline MVO2 was not different between WT (181 +/- 13 nmol.g(-1).min(-1)) and eNOS Tg (188 +/- 14 nmol.g(-1).min(-1)). BK decreased MVO2 (10(-4) mol/l) in WT by 17% +/- 1.1 and 33% +/- 2.7 in eNOS Tg (P < 0.05). CCh also decreased MVO2, 10(-4) mol/l, in WT by 20% +/- 1.7 and 31% +/- 2.0 in eNOS Tg (P <0.05). Forskolin (10(-6) mol/l) or SNAP (10(-4) mol/l) also decreased MVO2 in WT by 24% +/- 2.8 and 36% +/- 1.8 versus eNOS 31% +/- 1.8 and 37% +/- 3.5, respectively. N-nitro-L-arginine methyl ester (10(-3) mol/l) inhibited the MVO2 reduction to BK, CCh, and forskolin by a similar degree (P <0.05), but not to SNAP. Thus selective overexpression of eNOS in cardiac blood vessels in mice enhances the control of MVO2 by eNOS-derived NO.

Animals↗
PubMed2004

Wess-Zumino current and the structure of the decay tau- -->K- pi- K+ nu tau.

We present the first study of the vector (Wess-Zumino) current in tau(-)-->K-pi-K+nu(tau) decay using data collected with the CLEO III detector at the Cornell Electron Storage Ring. We determine the quantitative contributions to the decay width from the vector and axial vector currents. Within the framework of a model by Kühn and Mirkes, we identify the quantitative contributions to the total decay rate from the intermediate states omegapi, rho(')pi, and K*K.

Journal Article↗
PubMed2004

Observation of the Hadronic transitions chi(b1,2)(2P)-->omegaUpsilon(1S).

The CLEO Collaboration has made the first observations of hadronic transitions among bottomonium (bbmacr;) states other than the dipion transitions among Upsilon(nS) states. In our study of Upsilon(3S) decays, we find a significant signal for Upsilon(3S)-->gammaomegaUpsilon(1S) that is consistent with radiative decays Upsilon(3S)-->gammachi(b1,2)(2P), followed by chi(b1,2)(2P)-->omegaUpsilon(1S). The branching ratios we obtain are B[chi(b1)(2P)-->omegaUpsilon(1S)]=(1.63(+0.35+0.16)(-0.31-0.15))% and B[chi(b2)(2P)-->omegaUpsilon(1S)]=(1.10(+0.32+0.11)(-0.28-0.10))%, in which the first error is statistical and the second is systematic.

Journal Article↗
PubMed2004

Posterior cervicothoracic instrumentation in spine tumors.

STUDY DESIGN: We retrospectively review 32 patients who underwent posterior fixation for cervicothoracic junctional tumors. All patients possessed unstable or potential after surgery unstable spines as a result of either their tumors or the surgery performed. We examined cervicothoracic spine stability, maintenance of alignment, and associated complications. OBJECTIVES: To review our experience with 3 different posterior osteosynthesis systems applied to the cervico-thoracic junction for spinal tumors. Our review includes surgical outcomes and complications. The evolution through 3 different systems between 1994 and 1997 reflects our attempts to improve accuracy in light of variable facet and pedicle interspaces. Our goal is not to compare the efficacy of the systems but to assess the efficiency of cervicothoracic facet and transpedicular screw and plate or rod fixation. However, we will comment on why the evolution occurred. The 3 different systems share a similar characteristic. Each system employs posterior cervical facet screw fixation and thoracic trans-pedicular screw fixation. SUMMARY OF BACKGROUND DATA: Spinal disorders involving the cervicothoracic junction and specific instrumentation to this region have been sparsely described in the literature. METHODS: Between June 1994 and June 2000, 32 patients underwent surgery for spinal tumors involving the cervicothoracic junction at our institution. There were 27 males and 5 females. The ages ranged from 17 to 72 years with a mean age of 52 years. A total of 32 cervicothoracic instrumentations were performed. We used the R. Roy-Camille thoracolumbar plate in 20 patients, the cervico-thoracic plate in 8, and the Agora rod system in 4. In all, 96 lateral mass screws were implanted from C4 to C6, 54 into C7, and 180 pedicle screws from T1 to T8. Nineteen patients had lung cancer with vertebral body invasion (Pancoast tumors), 11 had metastasis to the cervicothoracic junction, 1 had a chondrosarcoma, and 1 had myeloma. In a first group consisting of 19 patients, a combination of anterior and extended posterior surgical approaches allowed complete en bloc resection of the tumors, including all invaded vertebrae. Four total vertebrectomies and 15 partial vertebrectomies were performed. A second group of 13 patients had only posterior palliative stabilizing procedures with laminectomy and cervicothoracic fixation. RESULTS: The follow-up period varied from 3 to 54 months, average 15 months. The average duration of survival for patients who underwent partial or total vertebrectomy was 16 months (range 3-54 months). The average duration of survival for patients who underwent palliative decompression and stabilization was 11 months (range 5-19 months). No changes in the sagittal alignment occurred during the immediate postoperative period for 30 patients. However, 2 mechanical failures occurred. Two patients experienced a clinically significant early increase in thoracic kyphosis and required revision of the posterior instrumentation. A 21-month minimum follow-up was available for 6 patients, in whom all implants were stable. We noted no screw, plate, or rod breakage in this series. No neurologic complications, including root impingement or spinal cord injury, or vertebral artery injury occurred related to screw insertion into either the thoracic pedicles (180 screws) or the cervical lateral masses (96 screws in C4-C5-C6 and 54 screws in C7). CONCLUSIONS: Posterior plate or rod and screw fixation is a good method of treatment for cervicothoracic instability in spine tumors. Facet screw fixation in the cervical spine with Roy-Camille drilling technique and transpedicular screw fixation in the thoracic spine provides an efficacious means by which to stabilize the cervicothoracic junction. This stabilization technique was effective even in cases of high postoperative instability, such as with partial or total vertebrectomy. This screw-type stabilization is clinically effective and well documented. The evolution through 3 different systems reflects our attempts to improve accuracy in light of variable facet and pedicle interspaces. Importantly, posterior instrumentation will not interfere with subsequent laminectomy or more extreme surgical procedures.

Adolescent↗
PubMed2004

Increasing ozone over the Atlantic Ocean.

Ship-borne ozone (O3) measurements over the Atlantic Ocean during the period from 1977 to 2002 show that O3 trends in the northern mid-latitudes are small. In contrast, remarkably large O3 trends occur at low latitudes and in the Southern Hemisphere, where near-surface O3 has increased by up to a factor of 2. The likely cause is the substantial increase of anthropogenic emissions of nitrogen oxides (NOx) associated with energy use in Africa, which has added to NOx from biomass burning and natural sources.

Journal Article↗
PubMed2004

Reference materials for analytical toxicology including doping control: freeze-dried urine samples.

The feasibility of freeze-dried urine samples containing doping agents to be used in intercomparison exercises and/or as reference materials has been evaluated. Freeze-dried urine samples containing caffeine, ephedrine derivatives (ephedrine, methylephedrine, norephedrine, pseudoephedrine and norpseudoephedrine), amphetamine derivatives (amphetamine, metamphetamine, 3,4-methylenedioxyamphetamine and 3,4-methylenedioxymethamphetamine) and testosterone and epitestosterone glucuronides have been evaluated. For preparation of the samples, blank urines previously subjected to filtration for clarification were fortified with standard solutions of the corresponding compounds and filtered under sterile conditions. Some aliquots of the sterile liquid samples were used for homogeneity testing, others were stored at -80 degree C for reference purposes, and the rest were subjected to lyophilisation. Freeze-dried urine samples were stored at 4-8 degree C and their stability was assessed for a period up to 18 months. Results obtained showed minimal differences (lower than 5%) between lyophilised and non-lyophilised aliquots (stored at -80 degree C) at all time periods except for amphetamine (up to 18%) and norpseudoephedrine (up to 10%). Nevertheless, such differences remained constant over the entire period of study, indicating that the loss of analytes was due to the initial lyophilisation process. The loss of analytes in freeze-dried samples was due to their volatility. Furthermore, an increase in pH by 1 unit was observed following reconstitution of samples prepared from drug-free urine of commercial origin.

Amphetamine↗
PubMed2004

The effects of price and policy on marijuana use: what can be learned from the Australian experience?

This research examines the responsiveness of the demand for marijuana to changes in its money price and criminal status using data on individuals from the Australian National Drug Strategy's Household Surveys (NDSHS). The results suggest that both the prevalence of marijuana use and the conditional demand for marijuana in the general population are responsive to changes in its money price. Significant differences are found in the effect of price on participation in marijuana use across age-groups, with participation by youth more price sensitive than participation by older age-groups. Similarly, the effect of the legal status of marijuana use on the participation decision is found to differ across age-groups and gender. Specifically, decriminalisation is associated with an increases in the prevalence of use by males over the age of 25. There is no evidence that decriminalisation significantly increases participation in marijuana use by either young males or females, or that decriminalisation increases the frequency of use among marijuana users.

Adolescent↗
PubMed2004

Alcohol and marijuana use among college students: economic complements or substitutes?

Previous research has shown that the recent tightening of college alcohol policies has been effective at reducing college students' drinking. Over the period in which these stricter alcohol policies have been put in place, marijuana use among college students has increased. This raises the question of whether current policies aimed at reducing alcohol consumption are inadvertently encouraging marijuana use. This paper begins to address this question by investigating the relationship between the demands for alcohol and marijuana for college students using data from the 1993, 1997 and 1999 waves of the Harvard School of Public Health's College Alcohol Study (CAS). We find that alcohol and marijuana are economic complements and that policies that increase the full price of alcohol decrease participation in marijuana use.

Adult↗
PubMed2004

Internal representation of movement in children with developmental coordination disorder: a mental rotation task.

Recent studies show that children with developmental coordination disorder (DCD) have difficulties in generating an accurate visuospatial representation of an intended action, which are shown by deficits in motor imagery. This study sought to test this hypothesis further using a mental rotation paradigm. It was predicted that children with DCD would not conform to the typical pattern of responding when required to imagine movement of their limbs. Participants included 16 children with DCD and 18 control children; mean age for the DCD group was 10 years 4 months, and for controls 10 years. The task required children to judge the handedness of single-hand images that were presented at angles between 0 degrees and 180 degrees at 45 degrees intervals in either direction. Results were broadly consistent with the hypothesis above. Responses of the control children conformed to the typical pattern of mental rotation: a moderate trade-off between response time and angle of rotation. The response pattern for the DCD group was less typical, with a small trade-off function. Response accuracy did not differ between groups. It was suggested that children with DCD, unlike controls, do not automatically enlist motor imagery when performing mental rotation, but rely on an alternative object-based strategy that preserves speed and accuracy. This occurs because these children manifest a reduced ability to make imagined transformations from an egocentric or first-person perspective.

Child↗
PubMed2004

A defective nontransmissible recombinant Sendai virus mediates efficient gene transfer to airway epithelium in vivo.

Recombinant Sendai virus (SeV)-mediated gene transfer to differentiated airway epithelial cells has shown to be very efficient, because of its ability to overcome the intra- and extracellular barriers known to limit gene delivery. However, this virus is transmission competent and therefore unlikely to be suitable for use in clinical trials. A nontransmissible, replication-competent recombinant SeV has recently been developed by deleting the envelope Fusion (F) protein gene (SeV/DeltaF). Here we show that SeV/DeltaF is able to mediate beta-galactosidase reporter gene transfer to the respiratory tract of mice in vivo, as well as to human nasal epithelial cells in vitro. Further, in an ex vivo model of differentiated airway epithelium, SeV/DeltaF gene transfer was not importantly inhibited by native mucus. When compared to the transmission-competent SeV in vivo, no difference in gene expression was observed at the time of peak expression. The development of an F-defective nontransmissible SeV, which can still efficiently mediate gene transfer to the airway epithelium, represents the first important step towards the use of a cytoplasmic RNA viral vector in clinical trials of gene therapy.

Adult↗
PubMed2004

A functional polymorphism in the succinate-semialdehyde dehydrogenase (aldehyde dehydrogenase 5 family, member A1) gene is associated with cognitive ability.

Succinate-semialdehyde dehydrogenase (SSADH) deficiency is a rare cause of learning disability. We have investigated SSADH to assess its contribution to cognitive ability in the general population in both case-control- and family-based analyses. Sequence analysis of SSADH revealed four changes affecting the encoded protein, only one of which had a minor allele whose frequency is even moderately common. We genotyped this functional polymorphism in 197 high-IQ cases, 201 average-IQ controls and 196 parent high-IQ offspring trios. The minor allele was significantly less frequent in high-IQ cases and was significantly less frequently transmitted by parents to high-IQ subjects than chance expectation. A previous study has shown that the minor allele encodes a lower activity enzyme than the major allele. These data suggest that higher SSADH activity is associated with higher intelligence across the general population. The effect is small, with each allele having an effect size translating to about 1.5 IQ points.

Aldehyde Oxidoreductases↗
PubMed2004

Suicidal behaviour in early psychosis.

OBJECTIVE: This was to determine the prevalence of suicidal behaviours prior to and during the first year of treatment in a comprehensive early psychosis program (EPP) and to identify predictors of suicidal behaviour. METHOD: In a cohort study of 238 subjects, patients were assessed at initial presentation to an EPP and 1 year later. Measures included a range of demographic variables, suicide attempts, depression, positive and negative symptoms, social functioning and substance misuse. RESULTS: Although 15.1% attempted suicide prior to program entry, only 2.9% made an attempt in the year after program entry and 0.4% completed suicide. No further attempts were seen in those with previous parasuicide. These rates are lower than other published rates for first-episode patients. CONCLUSION: It is possible that specifically designed first-episode programs can reduce the suicidal behaviour in this high-risk population. The low prevalence of attempted suicide makes modeling predictors difficult.

Analysis of Variance↗
PubMed2004

Effects of variation in particle size on biaxial flexural strength of two conventional glass-ionomer cements.

Conventional glass-ionomer cements (GICs) have a slow maturation time. Reduction in time of maturation may be achieved by acceleration of the setting reaction. One factor that assists this is the reduction in glass particle size producing a larger surface area for reaction. The resulting rapid set and more rapid maturation should potentially lead to less long-term degradation. Biaxial strength measurements were made with respect to time for two GICs of similar compositions but with differing particle size distributions at different time intervals after immersion in both water and artificial saliva. There was little difference between the strength of the two materials over periods up to 12 weeks. A theoretical estimation of the relative surface areas of glasses showed that, despite there being twice the surface area available for reaction for one glass, there was little difference in strengths values between the two materials at any of the times tested here. The similarity in strength values despite this substantial difference suggests that the larger particles may have a greater influence in the cement forming process.

Dental Stress Analysis↗
PubMed2004

Effects of ad libitum feeding on performance of different strains of broiler breeders.

(1) Tolerance to ad libitum feeding was compared in three genotypes of broiler breeder hens: a standard broiler breeder fed ad libitum (SA) or restricted (SR), a slow growing 'label' broiler breeder (L) and an experimental dwarf heavy broiler breeder (E). Two similar experiments were conducted in two distinct research centres. (2) Feed intake and body weight were measured every 3 weeks from hatch to 40 to 49 weeks of age. Egg production and egg abnormalities were recorded. The number of yellow follicles in ovaries was counted at the age of 32 weeks. (3) Body weight was stabilised at 2.2, 3.7 and 5.4 kg after 24 weeks of age in L, E and SA hens, respectively. Growth of the SR hens was similar to that of L up to 20 weeks and stabilised at a similar level to that of E hens after 30 weeks of age. (4) Sexual maturity was delayed by 6 weeks in restricted breeders compared to ad libitum fed hens that started to lay at 20 weeks. SA hens had low egg production and a high proportion of defective eggs, which was largely compensated for by feed restriction. However, productivity of SR hens remained lower than that of L breeders. (5) Compared to the low viability and reproductive fitness observed with SA hens, the E dwarf broiler breeder tolerated ad libitum feeding and had better egg production, fewer egg abnormalities and yellow follicles per ovary and a higher egg production. However, laying rate was still lower than that of the SR and L groups. Energy conversion (kJ/g egg) from 32 to 40 weeks of age was much higher in the SA group than in the other three groups. 6. The feasibility of feeding a dwarf broiler breeder ad libitum calls for further research on implications of specific IGF and GH-receptor expression at the level of the ovary in dw chickens.

Aging↗
PubMed2004

Type 3 von Willebrand disease: assessment of complications and approaches to treatment -- results of a patient and Hemophilia Treatment Center Survey in the United States.

It has been reported many times that the optimal treatment of patients with von Willebrand disease (VWD) has yet to be determined. To assist in achieving this goal, the aim of this survey was as follows: to collect information on current treatment practices; to determine the impact of the disease in type 3 VWD patients in the USA and to gain insight into the perceived and actual role that prophylaxis therapy plays in patient management. Nurse coordinators of the 146 federally funded Hemophilia Treatment Centers (HTCs) in the USA were contacted and informed of the survey and its goals. Those caring for type 3 VWD patients and willing to participate in the survey were mailed two questionnaires. The first questionnaire addressed the overall VWD patient population at their centre and asked questions relating to treatment practices. The second questionnaire focused on the impact that type 3 VWD has upon a patient's life. Thirty-four centres responded to the survey, providing a 48% response rate within the available pool of those centres treating type 3 VWD patients. Seventy-nine patients, with a mean age of 24.2 years, reported their primary causes of bleeding as; epistaxis (53.9%); joint bleeds (40.9%); dental bleeds (27.6%) and heavy menstrual bleeding (23.7%). There were a mean number of 9.2 reported non-life-threatening bleeds per year and a mean of 0.7 reported life-threatening bleeds per year. Forty percent reported lost days from school or work, caused by bleeds or other VWD complications. Sixty-two percent reported no joint damage. Regarding current treatment practices, 88.6% of respondents stated that their centre treated on demand and 13.9% used a prophylactic treatment regimen. Seventy-three percent of respondents felt that prophylaxis was either very or extremely helpful. This survey helps to document current treatment practices and morbidity exhibited by type 3 VWD patients. The results highlight the discrepancy between the use of prophylactic therapy, its perceived value and the level of joint damage and other morbidity experienced in this population.

Adolescent↗