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Biomedical subjects

R J Dennis

Publications and source records attributed to R J Dennis.

At least 19 recordsLinked to original sources
PubMed2005

Is bowling workload a risk factor for injury to Australian junior cricket fast bowlers?

OBJECTIVES: To examine whether bowling workload is a risk factor for overuse injury to Australian junior cricket fast bowlers and to evaluate the appropriateness of current bowling workload guidelines. METHODS: Forty four male fast bowlers (mean (standard deviation) age 14.7 (1.4) years) were monitored prospectively over the 2002-2003 season. Bowlers completed a daily diary to record bowling workloads and self reported injuries, which were validated by a physiotherapist. Bowling workload prior to the first injury (for those bowlers who were injured) was compared to workload across the whole season for uninjured bowlers. RESULTS: Eleven (25%) bowlers reported an overuse-type injury, with seven of these sustaining a back injury. Injured bowlers had been bowling significantly more frequently than uninjured bowlers (median number of days since the previous bowling day: 3.2 v 3.9 days, Mann-Whitney U = 105.0, p = 0.038). Compared with bowlers with an average of > or =3.5 rest days between bowling, bowlers with an average of <3.5 rest days were at a significantly increased risk of injury (risk ratio (RR) = 3.1, 95% confidence interval (CI) 1.1 to 8.9). There were also trends towards an increased risk of injury for those who bowled an average of > or =2.5 days per week (RR = 2.5, 95% CI 0.9 to 7.4) or > or =50 deliveries per day (RR = 2.0, 95% CI 0.7 to 5.4). CONCLUSIONS: This study has identified high bowling workload as a risk factor for overuse injury to junior fast bowlers. Continued research is required to provide scientific evidence for bowling workload guidelines that are age-specific for junior fast bowlers.

Adolescent↗
PubMed2002

[Factors associated with hospital mortality in patients admitted to the intensive care unit in Colombia].

OBJECTIVES: To describe the demographic features, reasons for hospital admission and factors associated with hospital mortality in patients admitted to intensive care in Colombia. METHOD: A cohort study of patients admitted to intensive care units (ICUs). Of 89 ICUs identified in Colombia, 20 in ten cities were invited to gather information on 200 consecutive patients admitted to each ICU. RESULTS: Three thousand sixty-six patient cases were available for analysis. The mean age was 53 years and 43% were women (men vs. women, p < 0.001). The most frequent cause of admission was medical (63.9%), acute myocardial infarction patients (7.1%) comprising the largest group. Severity of disease measured as APACHE II and III was a mean 14.0 (SD 6.9) and 48.3 (SD 23.5), respectively. Multivariate analysis, independent of adjustment for severity (APACHE II or III), showed that the factors associated with hospital death were the need for mechanical ventilation, pupillary response, transfer from a medical ward, and management by the ICU team prior to admission (p < 0.01). CONCLUSION: The most common reason for admission to an ICU in Colombia was myocardial infarction. Besides severity of disease, other variables related to medical care in Colombia are associated with hospital mortality, such as invasive ventilation. Although these variables may be artifacts related to disease severity, they are more likely to be related to quality of care.

APACHE↗
PubMed2001

Ethical challenges in pharmacoepidemiological research in Colombia.

PURPOSE: To illustrate and to discuss some ethical challenges encountered during pharmacoepidemiological research in a developing country (Colombia), as well as the decisions made to solve them. METHODS: The authors in Bogotá describe three recent studies. The first one collected data from clinical records to evaluate the prescriptions patterns in recently graduated physicians. The second used an interrupted time series design, with a set of observations prior and after a combined intervention, to assess whether it improved the quality of intravenous antibiotic prescribing practices in a university-based hospital. The third evaluated pharmacists' advice in childhood acute respiratory infection and acute diarrhea through a community survey, followed by focus groups and in-depth interviews of key informers. RESULTS: The ethical issues raised by these studies include the need for obtaining informed consent from participants (physicians in Study 1 and drug sellers in Study 3), deciding when to intervene in case of gross prescription mistakes detected during the collection of data as part of the time series assessment (Study 2), the use of simulated clients to collect data in the community survey, and the use of study resources to buy, in some cases, useless medications (Study 3). CONCLUSION: Although ethical challenges in pharmacoepidemiology in non-industrialized countries like Colombia may be different from those in developed nations, ethical principles that guide research remain the same. The processes to safeguard these principles in Colombia for virtually all research are also universal in nature, and include the ethical review committee, subject privacy, informed consent, and disclosure of funding sources.

Anti-Bacterial Agents↗
PubMed1999

Functional reach improvement in normal older women after Alexander Technique instruction.

BACKGROUND: Functional reach (FR) is a clinical measure of balance. The Alexander Technique (AT) is a nonexercise approach to the improvement of body mechanics. This study investigated a possible relationship between FR performance and AT instruction. METHODS: Three groups comprised of women older than 65, with the exception of one male control, were studied: (i) a pilot group, and (ii) experimental and (iii) control groups. Groups 1 and 2 were given eight 1-hour, biweekly sessions of AT instruction with pre- and posttests in FR, whereas Group 3 was given only pre- and posttests in FR. RESULTS: Groups 1 and 2 both showed significant improvement in FR performance. Group 2 was retested 1 month after posttest and showed a slight decrease in FR performance. For Groups 1 and 2, a questionnaire allowing qualitative responses on a four-item scale showed an overall positive response to the AT instruction. CONCLUSIONS: AT instruction may be effective in improving balance and thereby reducing the incidence of falls in normal older women.

Accidental Falls↗
PubMed1998

Novel natural product 5,5-trans-lactone inhibitors of human alpha-thrombin: mechanism of action and structural studies.

High-throughput screening of methanolic extracts from the leaves of the plant Lantana camara identified potent inhibitors of human alpha-thrombin, which were shown to be 5,5-trans-fused cyclic lactone euphane triterpenes [O'Neill et al. (1998) J. Nat. Prod. (submitted for publication)]. Proflavin displacement studies showed the inhibitors to bind at the active site of alpha-thrombin and alpha-chymotrypsin. Kinetic analysis of alpha-thrombin showed tight-binding reversible competitive inhibition by both compounds, named GR133487 and GR133686, with respective kon values at pH 8.4 of 1.7 x 10(6) s-1 M-1 and 4.6 x 10(6) s-1 M-1. Electrospray ionization mass spectrometry of thrombin/inhibitor complexes showed the tight-bound species to be covalently attached, suggesting acyl-enzyme formation by reaction of the active-site Ser195 with the trans-lactone carbonyl. X-ray crystal structures of alpha-thrombin/GR133686 (3.0 A resolution) and alpha-thrombin/GR133487 (2.2 A resolution) complexes showed continuous electron density between Ser195 and the ring-opened lactone carbonyl, demonstrating acyl-enzyme formation. Turnover of inhibitor by alpha-thrombin was negligible and mass spectrometry of isolated complexes showed that reversal of inhibition occurs by reformation of the trans-lactone from the acyl-enzyme. The catalytic triad appears undisrupted and the inhibitor carbonyl occupies the oxyanion hole, suggesting the observed lack of turnover is due to exclusion of water for deacylation. The acyl-enzyme inhibitor hydroxyl is properly positioned for nucleophilic attack on the ester carbonyl and therefore relactonization; furthermore, the higher resolution structure of alpha-thrombin/GR133487 shows this hydroxyl to be effectively superimposable with the recently proposed deacylating water for peptide substrate hydrolysis [Wilmouth, R. C., et al. (1997) Nat. Struct.Biol. 4, 456-462], suggesting the alpha-thrombin/GR133487 complex may be a good model for this reaction.

Acylation↗
PubMed1998

Prescription patterns of recently graduated physicians in Colombia: a survey during the mandatory social work period.

MAIN OBJECTIVE: To quantify prescribing patterns of physicians during their year of social work in health centers of Bogotá, Colombia, for three tracer conditions: acute respiratory infection (ARI), systemic hypertension (SH) and acute diarrhea (AD). DESIGN: Cross-sectional survey. SETTING: Primary Care Health Centers in the city of Bogotá. STRATEGY: The Health District Department of Bogotá (Secretaria Distrital de Salud) provided the sampling frame of SILOS (Local Health System) and UPAS (primary health service units) with a physician in the social work year. Samples of patient-physician encounters for the three tracer conditions within UPAS were examined, and detailed information collected on prescription indicators. RESULTS: Information was collected on a total of 1099 patient-physician encounters. Results show that 61% (95% CI: 58.6-63.1) of prescriptions in these settings are non-generic, and only 62% (95% CI: 59.5-64.0) are from the Colombian essential drug list. Number of medications prescribed per encounter were higher with ARI, as well as prescriptions for non-generic forms, antibiotics, and medications outside of the Colombian essential drug list. Inappropriate prescriptions were seen in 31% (95% CI: 28.1-33.7) of all encounters. DISCUSSION: Inadequacy of prescriptions (based on diagnosis) suggest that the teaching of rational prescribing patterns should be targeted with much more emphasis in schools of medicine. Interventions focused on the outstanding deficiencies should be designed and properly evaluated.

Journal Article↗
PubMed1998

A comparison of stereopsis with ANVIS and F4949 night vision goggles.

BACKGROUND: This study was undertaken to see if the model of NVG affects stereoacuity. METHODS: We tested 13 male and 2 female aircrew with the Aviator's Night Vision Imaging System (ANVIS) and F4949 NVGs. Visual acuity was measured using the NVG Resolution Grid and stereopsis was determined using a modified Howard-Dolman test. RESULTS: In simulated light conditions, average stereoscopic threshold using the F4949 NVG (17.35 arc s) was not significantly better than the ANVIS NVG (18.42 arc s), the mean difference being 1.07 arc s (95% confidence limits, -2.85 to 4.99). CONCLUSIONS: The Howard-Dolman test proved to be effective in eliminating monocular clues, thus validating its use in testing NVG stereopsis. The distribution of visual acuities across subjects and goggle models was too narrow to evaluate the effect of visual acuity on stereoacuity in NVGs. Differences in trial means during the course of the study indicated the presence of a "learning" effect on the Howard-Dolman test.

Adult↗
PubMed1996

Woodsmoke exposure and risk for obstructive airways disease among women.

OBJECTIVE: To investigate if exposure to firewood smoke and other indoor pollutants is a potential risk factor for obstructive airways disease (OAD) among women in Bogota in whom cigarette smoking and other known risk factors may not be the most frequent. DESIGN AND SETTING: We conducted a hospital-based case-control study to identify risk factors for OAD among women in Bogota. An interview was conducted using a modified questionnaire recommended by the American Thoracic Society for epidemiologic studies. PATIENTS: We compared 104 OAD cases with 104 controls matched by hospital and frequency matched by age. ANALYSIS: The odds ratio (OR) was used as the basic statistic to evaluate risk. Multivariate analysis (MA) was conducted by the Mantel-Haenszel procedure and by logistic regression. MAIN RESULTS: Univariate analysis showed that tobacco use (OR = 2.22; p < 0.01), wood use for cooking (OR = 3.43; p < 0.001), passive smoking (OR = 2.05; p = 0.01), and gasoline use for cooking (OR = 0.52; p = 0.02) were associated with OAD. Trends for years of tobacco use and years of wood cooking were present (p < 0.05). After MA, variables remained significant except gasoline use. CONCLUSIONS: This study showed that among elderly women of low socioeconomic status in Bogota, woodsmoke exposure is associated with the development of OAD and may help explain around 50% of all OAD cases. The role of passive smoking remains to be clarified. This work may set the basis for interventional studies in similar settings.

Adult↗
PubMed1996

The USAF Aircrew Medical Contact Lens Study Group: operational problems.

BACKGROUND: Although soft contact lens (SCL) wear for aircrew with refractive errors was approved in June 1989, aircrew with certain ocular disorders, such as keratoconus, have been waivered to fly with contact lenses (CL) since the 1960's. These aircrew are members of the United States Air Force (USAF) Medical Contact Lens Study Group and are fitted [with SCL's or hard contact lenses (HCL)] and followed by the Ophthalmology Branch at Armstrong Laboratory; Brooks Air Force Base, TX. Because HCL's are perceived to be more susceptible to a disabling foreign body (FB) under a lens and are more difficult to remove in flight, Study Group aircrew are the only USAF HCL wearers allowed to fly. METHODS: The medical records of the 142 aircrew members followed for CL wear between 1970 and 1993 were retrospectively examined to determine the type of CL worn, crew position, and the medical reason for CL wear. The Study Group was then surveyed to ascertain whether there were any significant operational problems for aircrew wearing medically indicated CL's. Aircrew were divided into HCL (51 surveys returned) and SCL (44 surveys returned) wearers to compare each modality's efficacy in the flight environment. RESULTS: HCL wearers were more likely than SCL wearers to have endured at least one FB incursion under a lens during flight (p = 0.053). HCL wearers were also more likely to have had a lens come off-center at least once in their careers during flight (p = 0.035). Both groups reported problems with CL dryness in the 5-15% relative humidity of the cockpit. Only four aircrew reported any CL-related Duties Not Involving Flying (DNIF) days during their careers. CONCLUSION: Because HCL's are necessary to correct vision adequately to return aircrew with keratoconus and other corneal anomalies to the cockpit, the USAF needs to continue to investigate the use of rigid gas-permeable HCL's with aircrew.

Aerospace Medicine↗
PubMed1995

The role of optometry in the USAF vision research program.

BACKGROUND AND METHODS: Optometry has played a significant role in the USAF vision research program since the early 1960s. The Air Force Institute of Technology (AFIT) sponsors active duty optometry officers for Ph.D. and masters programs in Physiological Optics at civilian universities. After training, they are assigned to research laboratories at Brooks AFB, TX, or Wright-Patterson AFB, OH. Senior research optometrists manage vision and medical research programs and have served on the staff of the United States Air Force (USAF) Surgeon General. RESULTS AND CONCLUSIONS: Research papers reporting on USAF vision research programs, especially those germane to improving aircrew combat effectiveness, have been published extensively by USAF optometrists in Air Force and joint services technical reports as well as the open literature. These programs include: refractive error trends, contact lenses, ophthalmic materials, night vision, aircraft transparency measurement, nuclear flashblindness, laser, and space flight. As long as vision remains the most important sensory input to the pilot, USAF optometrists will remain an integral part of the aerospace medical research team.

Aerospace Medicine↗
PubMed1993

Aircrew soft contact lens wear: a survey of USAF eyecare professionals.

The USAF, when it approved soft contact lens (SCL) wear for aircrew in June 1989, chose a conservative approach that authorizes only daily-wear of extended-wear SCL's. The aircrew SCL program has been perceived as a success, and follow-up data are no longer being collected. A survey was sent to all USAF eyecare professionals to assess the types and extent of SCL-related ocular pathology, the magnitude of environmental SCL problems in the cockpit, and the brands of SCL's that are being fitted. Only two instances of ulcerative keratitis were reported. The most severe inflight problem reported was the dry cockpit environment. CSI-T (Pilkington Barnes-Hind) was the most frequently used spherical lens and the Hydrasoft Toric XW (CoastVision) was the most used toric lens. The USAF aircrew SCL program appears to be progressing successfully. However, the Ophthalmology Branch at Armstrong Laboratory will continue to monitor the program for serious medical complications.

Aerospace Medicine↗
PubMed1992

The medical acceptability of soft contact lens wear by USAF tactical aircrews.

Seventy-two Tactical Air Command (TAC) aircrew members completed one full year of soft contact lens (SCL) wear. A daily-wear regimen, using extended-wear lenses, was used to minimize corneal stress. Baseline measurements of visual acuity with SCLs and with spectacles after SCL removal and ocular indicator gradings were compared to measurements at 5-d, 10-d, 1-month, 3-month, 6-month, and 12-month examinations. Visual acuity did not decrease during the test. No aircrew member developed corneal ulcers or other serious complications requiring elimination from the test. Two aircrew members lost a total of 9 "duties not to include flying" (DNIF) days: one flyer was grounded for 1 d with a corneal abrasion and another for 8 d with epithelial microcysts. The TAC SCL Test, as designed, was generally successful. The conservative approach to SCL wear during the test and the meticulous follow-up care by United States Air Force eye care professionals most likely contributed to the low ocular complication rate.

Aerospace Medicine↗
PubMed1992

Contact lens wear with the USAF Protective Integrated Hood/Mask chemical defense ensemble.

The Protective Integrated Hood/Mask (PIHM) chemical defense aircrew ensemble blows air from the mask's plenum across the visor at a rate of approximately 15 L/min in order to prevent fogging of the visor and to cool the aircrew member's face. This study was designed to determine the effect of the PIHM airflow on soft contact lens (SCL) dehydration, contact lens comfort, and corneal integrity. There were 26 subjects who participated in this study: 15 SCL wearers, 6 rigid gas-permeable (RGP) wearers, and 5 nonspectacle wearing controls. Contrast acuity with the 3 Regan charts, subjective comfort, and relative humidity (RH) and temperature readings under the PIHM mask were monitored every 0.5 h during 6-h laboratory rides. Slit-lamp examinations and SCL water content measurements with a hand-held Abbe refractometer were made before and after the rides. High RH under the mask may have accounted for the moderate SCL dehydration (8.3%), no decrease in contrast acuity for any group, and lack of corneal stress. Although all groups experienced some inferior, epithelial, punctate keratopathy, RGP wearers had the most significant. SCLs performed relatively well in the PIHM mask environment. Testing with other parameter designs is necessary before recommending RGPs with the PIHM system.

Aerospace Medicine↗
PubMed1991

Risk factors for multiorgan failure: a case-control study.

The aim of this study was to identify factors associated with Multiple Organ Failure (MOF), and assess possible interactions between the risk factors identified as such. We studied 40 MOF cases and 120 controls, out of all the surgery and trauma patients who needed intensive care at our institution in a 24-month period. The univariate analyses showed that age, hypovolemic shock, massive volume administration (MVA), sepsis, and time of evolution before arriving to the hospital (TE) were significantly associated with MOF. Logistic regression analysis showed that neither age nor MVA were independently associated with MOF after adjusting for all of the other variables. Interactions seemed to be present between age, sepsis, and shock. We conclude that in our surgery and trauma ICU adult patient population, hypovolemic shock, sepsis, and TE are independent risk factors for MOF. The importance of the association between shock and sepsis is discussed, as well as the possible relevance of TE as a risk factor.

Blood Transfusion↗
PubMed1991

The durability of hydrogel extended-wear contact lenses worn for daily wear by USAF aircrew members.

Hydrogel extended-wear contact lenses, worn on a daily-wear regimen, were tested for 1 year by USAF aircrew members. A total of 62 eyes were fitted with Hydrocurve II (55% water content) spherical lenses, 29 with Hydrocurve II (55% water content) toric lenses, and 61 with CSI-T (38.5% water content) spherical lenses. The mean lens replacement rate for torn lenses per aircrew member was determined to be 1.45 lenses a year. The replacement rate of Hydrocurve II spherical lenses compared to CSI-T lenses was not statistically significant. However, the replacement rate for Hydrocurve II toric lenses was significantly lower than both Hydrocurve II spherical lenses and CSI-T lenses (p less than 0.01). The extended-wear lenses tested in this study appeared to be durable enough for the rigors of daily wear.

Adult↗
PubMed1990

Survey of spectacle wear and refractive error prevalence in USAF pilots and navigators.

A retrospective survey of 5000 active aircrew records was performed at 12 United States Air Force (USAF) bases to obtain information about the prevalence of spectacle wear and refractive error. The data revealed that 27.4% of pilots and 51.5% of navigators/weapons systems operators (Nav/WSO) required spectacles when flying. Of the spectacle-wearing pilots, 12.4% required bifocals. Myopia was the predominant refractive error and a relatively large percentage of aircrew members had astigmatism of 0.75 D or more, e.g., 33.1% of pilots. At the time of entry into the USAF, refractive error data were clustered around emmetropia with a definite skew toward hyperopia.

Adult↗