Biomedical subjects

R C Wood

Publications and source records attributed to R C Wood.

At least 19 recordsLinked to original sources

PubMed2001

Spectral broadening of sound scattered by advecting atmospheric turbulence.

Scattering and spectral broadening of a monochromatic sound wave by atmospheric turbulence that is flowing with a uniform constant horizontal wind is considered. The acoustic source and a detector are at rest and at different positions in a ground-fixed frame. Analytic expressions are derived for the sound pressure scattered to the detector by a single eddy. Since distances and the scattering angle change with time as the eddy flows through the scattering volume, the detector signal has time-dependent amplitude and frequency, for which general formulas are derived. A computer code is developed that calculates the scattered signal and its Fourier transform from a single eddy, or from a steady-state collection of eddies of many different scale lengths that represents isotropic homogeneous turbulence flowing with the wind. The code utilizes a time-shift algorithm that reduces the calculation time substantially. Several numerical results from this code are presented, including simulations of a recent experiment. The predicted spectral shape, including peak width and jaggedness, are in good agreement with experiment.

Journal Article↗

PubMed2000

The maximum motor fusion test: a parameter for surgery for acquired esotropia.

PURPOSE: The purpose of this study was to determine whether surgery for acquired esotropia based on the maximum capacity for motor fusion measured with a prism bar could be used to increase the number of millimeters of bilateral medial rectus recession that could be performed without producing an early overcorrection or a late consecutive exotropia, as a way safely to reduce the need for postoperative wear of glasses or a bifocal. METHODS: Category I patients had residual deviations of esotropia (ET) of 12 PD or more with distance fixation, measured after a full hyperopic correction of +1.50 to +3.25 was placed, and had no significant anisometropia or astigmatism. Category II patients had residual deviations of esotropia of less than 11 PD with distance fixation and had residual deviations of esotropia with near fixation (ET') of at least 10 PD more than esotropia with distance fixation ("clinical high AC/A"). Category III patients had had previous bilateral medial rectus muscle recessions and had recurrent esotropia with near fixation of more than 10 PD. For patients in categories I and II, bilateral medial rectus muscle recessions were performed by using a published dose-response table from the national Prism Adaptation Study but with the maximum capacity for motor fusion as the input parameter instead of the prism-adapted angle. Patients in category III received re-recessions of one or both medial rectus muscles, according to a previously published system, with the distance fusional amplitude as the input parameter. RESULTS: In category I, 24 of 30 (80%) patients needed no glasses after surgery, 1 of 30 had esotropia, and 2 of 30 had exotropia (XT) (10% reoperation rate). In category II, 35 of 36 (98%) patients needed no bifocals after surgery, and 3 of 36 had exotropia (9% reoperation rate). In category III, 10 of 10 patients needed no bifocals, and 2 of 10 had exotropia (20% reoperation rate). CONCLUSIONS: When a postoperative reduction in dependence on continuous wear of an optical appliance is a reasonable goal, the maximum motor fusional capacity, measured with a prism bar, is a good parameter for surgical design.

Child, Preschool↗

PubMed2000

Prevalence, incidence, and risk factors associated with hip fractures in community-dwelling older Mexican Americans: results of the Hispanic EPESE study. Establish Population for the Epidemiologic Study for the Elderly.

OBJECTIVES: To determine the rates and risk factors associated with hip fractures in the community-dwelling older Mexican-American population. DESIGN: A prospective survey of a regional probability sample of older Mexican Americans aged 65 and over. SETTING: The 1993-1996 Hispanic Established Population for the Epidemiologic Study of the Elderly (H-EPESE), a probability sample of noninstitutionalized Mexican Americans, aged 65 and over, living in the Southwestern states of Texas, New Mexico, Colorado, Arizona, and California. PARTICIPANTS: In 1993-1994 and in 1995-1996, 2895 persons, aged 65 and over, considered Mexican American, were selected at baseline as a weighted probability sample. Sample weights were used to extrapolate to the estimated 498,176 older Mexican Americans residing in the Southwest US. MEASUREMENTS: Self-reported hip fracture and functional measures by in home interviews. RESULTS: Hip fracture prevalence was 4.0% at baseline. The overall incidence of hip fractures for women was 9.1 fractures/1000 person-years. The incidence rate for men was 4.8 fractures/1000 person-years. Extrapolation from these data to the entire older Mexican American population indicated that approximately 5162 new fractures occurred in the population during the 2 year study period. In women, hip fractures were associated independently with advanced age, not being married/living alone, having had a stroke, limitations with activities of daily living and instrumental activities of daily living. In men, only the latter limitations were associated independently with hip fracture. CONCLUSIONS: This study indicates that older Mexican American people may have hip fracture incidence rates that place them at highest risk among the Hispanic subgroups. In light of a sparse literature on this population, the fracture estimates derived from this work contributes to our understanding of the true fracture estimates in this population. Based on the extrapolated population rates, hip fracture in this population is a significant public health problem. Adequate preventive measures need to be implemented in this growing US population.

Activities of Daily Living↗

PubMed2000

A three dimensional surgical dose-response schedule for lateral rectus resections for residual congenital/infantile esotropia after large bilateral medial rectus recessions.

PROBLEM: A series of overcorrections after this surgical sequence. SUBJECTS & METHODS: Forward stepwise multiple regression analysis of the effect of bilateral lateral rectus resections, retrieved and tabulated retrospectively from the clinical charts of 50 children with infantile esotropia who had significant residual non- accommodative esotropia after bilateral medial rectus recessions. Analysis allowed for selection among linear and quadratic forms of two relevant predictor variables: the mm of previous bilateral medial rectus recession and the prism diopters of residual esotropia. RESULTS: We found a correlation between the effect of the second surgery (bilateral LR resections) and the two variables. This relation could be expressed by a surgical dose-response schedule-surface with the formula: [2.39 + 0.26 (mm MR recession) Squared + 0.41 (mm LR Resection) Squared = prism diopters of effect]. A corresponding schedule (table) with these two parameters was developed to facilitate clinical application. To test and prove this schedule, we re-studied 19 of the 50 original cases who had had surgery, fortuitously, +/-0.3 mm of our new surgical dose- response surface-schedule plus 10 new cases performed according to the new surface-schedule. For these 29 cases there was only one "failure" at 6 months postop' (3%). As a control, for the 31 cases of the original 50 whose surgery had not been within +/- 0.3 mm of the new schedule, 7/31 (23%) were "failures", all overcorrections. ("Failure" vs. "success" - there were only two categories of outcome - was defined as an esotropia over 8 PD or exophoria over 6 PD.) CONCLUSION: This difference in results, expressed as "successes" of 28/29 vs 24/31, or 97% vs 77% gave, on statistical analysis, a p=0. 053 of rejecting the null hypothesis, which is considered a valid "trend" or marginally "statistically significant" and definitely "clinically-medically significant". We have adopted the regular application of our new surgical dose- response schedule in these cases and recommend it for all such cases. binocular vision; complications, surgical; dose-response surgical schedule; esotropia, congenital/infantile; lateral rectus muscle, resection; outcomes; overcorrections; strabismus surgery; study, retrospective, clinical; surgery, strabismus.

Accommodation, Ocular↗

PubMed1999

Antielevation syndrome after bilateral anterior transposition of the inferior oblique muscles: incidence and prevention.

BACKGROUND: Unilateral and bilateral anterior transpositions of the inferior oblique muscle (ATIOs) for primary inferior oblique (IO) muscle overaction may produce apparent new or recurrent overaction of the contralateral IO muscle. This effect has been termed "antielevating" and can produce overaction of the contralateral elevators in adduction that mimics recurrent or new overaction of the IO muscle of the other eye. This phenomenon may be termed the antielevation syndrome (AES). Kushner has hypothesized that this complication of the ATIO is produced primarily by the posterior fibers of the IO muscle. The purpose of this study is to correlate the frequency of this syndrome in a large series of patients with the mm of lateral displacement (spreading) of the IO muscle reattachment site. METHODS: There was a combination of 123 patients who received ATIO from Mims and 77 patients who received ATIO from Kushner. ATIO was performed according to a previously published technique. RESULTS: All 16 patients (14 from Mims and 2 from Kushner) with AES had received bilateral anterior transposition of the posterior fibers of the IO muscle to at least 2 mm anterior to the lateral end of the inferior rectus (IR) muscle with spreading laterally 3 to 5 mm. Among children who had the posterior fibers of their IO muscles placed 2 to 4 mm anterior to a line drawn laterally from the insertion of the IR muscle, the incidence of AES was significantly larger with more spreading out of the new IO muscle insertion. CONCLUSIONS: AES may be prevented by attaching the posterior fibers of the IO muscle no more than 2 mm lateral to the IR muscle insertion site. This complication responds to bilateral nasal IO muscle myectomy in many cases.

Humans↗

PubMed1998

Correlates of prescription and over-the-counter medication usage among older Mexican Americans: the Hispanic EPESE study. Established Population for the Epidemiologic Study of the Elderly.

OBJECTIVES: To determine the prevalence rates of prescription and over-the-counter (OTC) medication usage among community-dwelling older Mexican Americans. DESIGN: Cross-sectional survey of a regional probability sample of older Mexican Americans. SETTING: The 1992-1997 Hispanic Established Population for the Epidemiologic Study of the Elderly (H-EPESE), a probability sample of noninstitutionalized Mexican Americans, age 65 and over, living in the five Southwestern states of Texas, New Mexico, Colorado, Arizona, and California. PARTICIPANTS: 2899 persons, age 65 and over, considered Mexican American, using appropriate weighting procedures to produce regional estimates. OUTCOME MEASURES: Use of prescription and OTC medication within the last 2 weeks before the survey confirmed by in-home review of medication containers. RESULTS: Medication users consumed a mean of 2.9 prescription and 1.3 OTC medications. Over half (58.9%, n = 1,798) of the participants used at least one prescribed medication, and 31.3% (n = 847) used at least one OTC medication within the 2 weeks before their participation in the study. Factors associated with both prescription and OTC medication usage were self-perceived health and number of co-morbid conditions. Factors associated only with prescription medication usage included female gender, alcohol usage, ADL dependency, and presence of additional insurance. Structural assimilation was associated only with OTC medication usage. CONCLUSIONS: These data show lower prevalence rates of prescription medication usage among Mexican American older men and lower rates of OTC medication usage in older Mexican Americans of both genders than previously reported in other ethnic groups. This may reflect differences in time and geographic location of the Hispanic EPESE relative to other EPESE studies, ethnic differences in access to care as reflected by insurance in addition to Medicare, ethnic differences in survival, especially among males, or ethnic differences in medication preferences.

Activities of Daily Living↗

PubMed1996

Involvement of methionine in the synthesis of certain membrane-associated nucleotide sugars by human amnion (WISH) cells.

A plasma membrane preparation from human amnion (WISH) cells contained uridine diphosphate sugars and methyl-uridine diphosphate (mUDP) sugars. The synthesis of mUDP-glucose, mUDP-mannose, and mUDP-fucose by the membrane preparation occurred when supplemented with uridine-5'-diphosphate-glucose and S-adenosyl-L-methionine. It is suggested that this newly recognized route for fucose biosynthesis might be employed by certain transformed cells, and may partly account for the methionine dependence of certain human tumors. Additionally, it is suggested that, in colon cancer, a deficiency of folic acid and methionine might affect mUDP-sugar biosynthesis rather than the methylation of DNA.

3T3 Cells↗

PubMed1996

Increased prevalence of the Taq I A1 allele of the dopamine receptor gene (DRD2) in obesity with comorbid substance use disorder: a preliminary report.

In order to investigate the prevalence of the Taq I A1 allele of the dopamine receptor gene (DRD2) in obesity with and without comorbid substance use disorder, a total of 40 patients, from an outpatient neuropsychiatric clinic in Princeton, New Jersey, were genotyped for presence or absence of the Taq I DRD2 A1 allele. The primary inclusion criterion for 40 obese subjects was a body mass index (BMI) equal to or over 25 (uncharacterized); 11 obese subjects had severe substance use disorder; 20 controls had a BMI below 25; and, 33 substance use disorder (less severe) patients had a BMI below 25. The data were statistically compared with three different sets of controls divided into three separate groups (Group I, n = 20; Group II, n = 286; Group III, n = 714). They differed according to screening criteria (drug, alcohol, nicotine abuse/dependence, BMI below 25 and other related behaviours including parental history of alcoholism or drug abuse and DSM IV, Axis I and Axis II diagnoses). Groups II and III were population controls derived from the literature. The prevalence of the Taq I A1D2 dopamine receptor (DRD2) alleles was determined in 40 Caucasian obese females and males. In this sample with a mean BMI of 32.35 +/- 1.02, the A1 allele of the DRD2 gene was present in 52.5% of these obese subjects. Furthermore, we found that in the 23 obese subjects possessing comorbid substance use disorder, the prevalence of the DRD2 A1 allele significantly increased compared to the 17 obese subjects without comorbid substance use disorder. The DRD2 A1 allele was present in 73.9% of the obese subjects with comorbid substance use disorder compared to 23.5% in obese subjects without comorbid substance use disorder. Moreover, when we assessed severity of substance usage (alcoholism, cocaine dependence, etc.) increasing severity of drug use increased the prevalence of the Taq I DRD2 A1 allele; where 66.67% (8/12) of less severe probands possessed the A1 allele compared to 82% (9/11) of the most severe cases. Linear trend analyses showed that increasing use of drugs was positively and significantly associated with A1 allelic classification (p < 0.00001). These preliminary data suggest that the presence of the DRD2 A1 allele confirms increased risk not only for obesity, but also for other related addictive behaviours (previously referred to as the Reward Deficiency Syndrome) and that a BMI over 25 by itself (without characterization of macroselection or comorbid substance use disorders) is not a sufficient criterion for association with the DRD2 A1 allele.

Adult↗

PubMed1996

The D2 dopamine receptor gene as a determinant of reward deficiency syndrome.

The dopaminergic system, and in particular the dopamine D2 receptor, has been profoundly implicated in reward mechanisms in the brain. Dysfunction of the D2 dopamine receptors leads to aberrant substance seeking behaviour (alcohol, drug, tobacco, and food) and other related behaviours (pathological gambling, Tourette's syndrome, and attention deficit hyperactivity disorder). We propose that variants of the D2 dopamine receptor gene are important common genetic determinants of the 'reward deficiency syndrome'.

Compulsive Behavior↗

PubMed1995

Involvement of folic acid in the synthesis of membrane-associated nucleotide sugars by normal and transformed mouse fibroblasts.

A plasma-membrane-containing fraction isolated from Swiss mouse (3T3) fibroblasts was found to contain uridine diphosphate sugars and methyl-uridine diphosphate (mUDP) sugars. The synthesis of the mUDP sugars by membrane preparations of normal and transformed 3T3 cells occurred from the intrinsic membrane uridine-diphosphate sugars + methylenetetrahydrofolic acid. Compared to the normal 3T3 cells, the synthesis of mUDP sugars by the transformed 3T3 cells was reduced by 49%. It is proposed that the plasma-membrane-associated mUDP sugars may be essential for normal cell growth.

3T3 Cells↗

PubMed1995

Assessment of a model for measuring drug diffusion through implant-generated fibrous capsule membranes.

Fibrous tissue, which encapsulates subcutaneously implanted silastic, vinyl, polyurethane and Teflon discs in rats, has been isolated, characterized and tested for drug permeability in order to develop an in vitro model for determining the effect of this tissue on drug disposition from implant sites. With all materials, capsule tissue thickness and collagen content (approximately 59%) was consistent from 2 to 4 months after implantation. Silastic implants afforded the most consistent and usable tissue in terms of thickness and lack of vascularity, and these capsule membranes were used for determining the transport of three model compounds in an in vitro diffusion cell model. The rank ordering of permeability through these membranes was estrone (60.2 x 10(-6) cm s-1) > 3-O-methylglucose (18.7 x 10(-6) cm s-1) > dextran of molecular weight 70 000 (5.6 x 10(-6) cm s-1), which is consistent with expectations based on the molecular weights and partitioning behaviour of the model compounds. The results of these studies indicate that implant-generated encapsulating membranes can be successfully isolated and employed to study drug diffusion in an in vitro model, providing a direct assessment of the barrier properties of encapsulating membranes.

3-O-Methylglucose↗

PubMed1995

Dopamine D2 receptor gene variants: association and linkage studies in impulsive-addictive-compulsive behaviour.

Drug and alcohol seeking behaviour has become a great global problem affecting millions of inhabitants with a cost to society in the billions. Dopaminergic reward pathways have frequently been implicated in the etiology of addictive behaviour. While other neurotransmitters have also been implicated, to date the only molecular genetic defect which has been found to associate with alcoholism, drug dependency, obesity, smoking, pathological gambling, attention-deficit-hyperactivity disorder (ADHD), Tourette syndrome, as well as other related compulsive behaviours, are the variants of the dopamine D2 receptor gene (DRD2). In this review of the available data on the subject, we report a number of independent meta-analyses that confirm an association of DRD2 polymorphisms and impulsive-additive-compulsive behaviour (IACB), which we have termed "Reward Deficiency Syndrome". While we agree that Meta-analyses of all exant studies support an association of variants of DRD2 and IACB, correct negative findings with alcoholism may be due to differences in assessing controls and inclusion/exclusion criteria for selection of diseased probands.

Behavior, Addictive↗

PubMed1994

Occupational exposure to human immunodeficiency virus (HIV)-infected blood in Denver, Colorado, police officers.

The authors undertook a study of Denver, Colorado, police department officers to measure their risk of exposure to blood and human immunodeficiency virus (HIV) by type of work assignment and to document how exposures occurred. From December 1989 through March 1991, 137 officers reported an exposure to either blood or saliva, and 42 exposures to blood were independently documented. The overall rate of exposure to HIV-infected blood for medium and high risk assignments was 0.10 per 10,000 person-days. Thirty-two source persons underwent voluntary testing for HIV antibodies, and five (15.6%) were seropositive. Two thirds of the 42 blood exposures occurred in circumstances in which 1) there was little or no time for the officer to put on protective gloves and clothing because the officer was restraining or being assaulted by a suspect or 2) gloves would have not been protective because of penetration by needles. The authors conclude that Denver police officers rarely have percutaneous or mucosal exposures to blood, but when they do, the risk of exposure to HIV-infected blood is quite high. A health department can provide to police officers a number of services: evaluation of an incident involving contact with blood or body fluids to determine whether there was potential for disease transmission; information about modes of transmission and prevention of bloodborne diseases; serologic testing of source persons; HIV counseling for exposed officers and source persons; documentation for worker's compensation claims; and consultation regarding the use of zidovudine for postexposure prophylaxis.

Adolescent↗

PubMed1994

Evaluation of clinical and laboratory aspects of antibody tests for detection of hepatitis C virus infection in blood donors and recipients from a low-risk population.

BACKGROUND: When the first-generation enzyme immunoassay (EIA) for detection of antibody to hepatitis C virus (anti-HCV) was approved in May 1990, blood banking agencies recommended testing of all components in inventory. In many cases, one or more components from these units had already been transfused. STUDY DESIGN AND METHODS: Donors that reacted in first-generation EIAs and recipients of their components were identified, and anti-HCV test methods (including first-generation EIA, second-generation EIA, and recombinant immunoblot assay [RIBA]) were evaluated. RESULTS: Of 66 donors identified as anti-HCV-positive by first-generation EIA, 17 were positive in second-generation EIA. Of these 17, 9 reacted in RIBA; 6 of these showed evidence of HCV infection in polymerase chain reaction (4) and/or probable transmission of HCV to a transfusion recipient (3). Of the 48 specimens that were positive in first-generation EIA and negative in second-generation EIA, only 1 was positive in RIBA; serum was not available for polymerase chain reaction testing, and there were no living transfusion recipients in whom to assess evidence of transmission of HCV. CONCLUSION: This study documents the low predictive value of EIAs for anti-HCV in a low-prevalence blood donor population and emphasizes the need for additional testing to confirm the specificity of samples that react in the screening tests.

Adolescent↗

PubMed1994

Prolonged P300 latency in a neuropsychiatric population with the D2 dopamine receptor A1 allele.

The role of the dopaminergic system in P300 has been implicated and previous studies have suggested the presence of a heritable component in the genesis of P300 or P3, a late positive component of the event-related potential. In the present investigation, 155 Caucasian male and female diagnosed neuropsychiatrically-ill patients with and without comorbid drug and alcohol abuse/dependence were genotyped for the presence or absence of the A1 allele of the D2 dopamine receptor gene (DRD2). The relationship of the A1 and A2 alleles to P3 amplitude and latency was also determined. The results showed no significant difference in P3 amplitude between all groups studied with A1 and A2 allele carriers. However, we now report prolonged P3 latency in neuropsychiatrically-ill patients (with or without polysubstance abuse) with those carrying two copies of the A1 allele (homozygote) of the DRD2 gene (quadratic trend, p = 0.01). Moreover, the age-adjusted mean P3 latency in the D2A2/A2 allele group was 327.8 +/- 3.08 ms compared by ANOVA, to 360.04 +/- 4.86 ms in the D2A1/A1 group. Our work suggests an association of polymorphisms of the DRD2 gene and a biological marker previously indicated to have predictive value in vulnerability to substance abuse.

Adult↗

PubMed1994

Involvement of folic acid and methionine in the synthesis of certain membrane-associated nucleotide sugars by Enterococcus hirae.

A membrane preparation from Enterococcus hirae contained UDP and methyl-UDP (mUDP) monosaccharides. This preparation, when incubated with combinations of folic acid, L-serine, and S-adenosyl-L-methionine in a reaction system containing UDP-glucose, promoted synthesis of certain mUDP sugars. Folic acid and serine produced mUDP-glucose and mUDP-rhamnose; S-adenosylmethionine produced mUDP-glucose, mUDP-mannose, and mUDP-fucose.

Cell Fractionation↗

PubMed1994

Mechanism of irrigation effects on gingivitis.

Although gingivitis is initiated by plaque and plaque removal controls gingivitis, gingival irrigation with water has been shown to reduce gingivitis without reducing plaque. This study attempted to explore possible mechanisms involved in the treatment of gingivitis by water irrigation. Patients (n = 125) with more than 20 teeth, less than 4 sites with probing depth (PD) deeper than 6 mm, bleeding on probing (BOP) frequency of 30% or higher, and no systemic disease were randomized to one of four treatment groups: toothbrushing alone (brush), toothbrushing plus chlorhexidine 0.12% rinse 2x/day (CHX), toothbrushing plus water irrigation 1x/day (irr+H2O), or toothbrushing plus chlorhexidine 0.04% irrigation 1x/day (irr+CHX). Six sites/tooth were examined at baseline, and at 3 and 6 months for BOP and PD using an automated probe, and for gingival index (GI) and plaque index (PI) by standard means. A prophylaxis and oral hygiene instructions were provided after baseline and 6 month measurements. Subgingival microbial samples and crevicular fluid (GCF) were collected from 2 teeth/subject at each time point. Microbial samples were processed for anaerobic culture and the predominant cultivable flora was determined. CHX and irr+CHX had a 30 to 35% decrease in mean PI, while brush and irr+H2O had only a 12 to 16% decrease. BOP was reduced by 14% in the brush group and 23 to 24% in the other groups. GI was significantly correlated with PI in the brush, CHX, and irr+CHX groups, but not in the irr+H2O group. Prevotella intermedia was significantly reduced in both irrigation groups, but not CHX or brush groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Allelic association of the D2 dopamine receptor gene with cocaine dependence.

The objective of the present study was to examine allelic prevalence of the D2 dopamine receptor (DRD2) gene in male cocaine-dependent (CD) Caucasian (non-Hispanic) subjects and to determine the relationship of DRD2 alleles to family history and selected behavioral measures. The prevalence of the A1 allele in CD subjects (n = 53) was 50.9%. It was significantly higher than either the 16.0% prevalence (P < 10(-4)) in non-substance abusing controls (n = 100) or the 30.9% prevalence (P < 10(-2)) in population controls (n = 265) wherein substance abusers were not excluded. Similarly, a significantly higher prevalence (P < 10(-2)) of the B1 allele was found in CD subjects (n = 52) compared with non-substance abusing controls (n = 53); 38.5% vs. 13.2%. Logistic regression analysis of CD subjects identified potent routes of cocaine use and the interaction of early deviant behaviors and parental alcoholism as significant risk factors associated with the A1 allele. The cumulative number of these three risk factors in CD subjects was positively and significantly (P < 10(-3)) related to A1 allelic prevalence. The data showing a strong association of the minor alleles (A1 and B1) of the DRD2 with cocaine dependence suggest that a gene, located on the q22-q23 region of chromosome 11, confers susceptibility to this drug disorder.

Adult↗