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Biomedical subjects

Guohua Li

Publications and source records attributed to Guohua Li.

At least 19 recordsLinked to original sources

Inpatient disposition classification for the creation of hospital surge capacity: a multiphase study.

BACKGROUND: The ability to provide medical care during sudden increases in patient volume during a disaster or other high-consequence event is a serious concern for health-care systems. Identification of inpatients for safe early discharge (ie, reverse triage) could create additional hospital surge capacity. We sought to develop a disposition classification system that categorises inpatients according to suitability for immediate discharge on the basis of risk tolerance for a subsequent consequential medical event. METHODS: We did a warfare analysis laboratory exercise using evidence-based techniques, combined with a consensus process of 39 expert panellists. These panellists were asked to define the categories of a disposition classification system, assign risk tolerance of a consequential medical event to each category, identify critical interventions, and rank each (using a scale of 1-10) according to the likelihood of a resultant consequential medical event if a critical intervention is withdrawn or withheld because of discharge. FINDINGS: The panellists unanimously agreed on a five-category disposition classification system. The upper limit of risk tolerance for a consequential medical event in the lowest risk group if discharged early was less than 4%. The next categories had upper limits of risk tolerance of about 12% (IQR 8-15%), 33% (25-50%), 60% (45-80%) and 100% (95-100%), respectively. The expert panellists identified 28 critical interventions with a likelihood of association with a consequential medical event if withdrawn, ranging from 3 to 10 on the 10-point scale. INTERPRETATION: The disposition classification system allows conceptual classification of patients for suitable disposition, including those deemed safe for early discharge home during surges in demand. Clinical criteria allowing real-time categorisation of patients are awaited.

Bed Occupancy↗

Patients who leave without being seen: their characteristics and history of emergency department use.

STUDY OBJECTIVE: We identify patient characteristics associated with uncompleted visits to the emergency department (ED). METHODS: We used registration and billing data to conduct a pair-matched case-control study. ED patients who left without being seen (cases) between July 1 and December 31, 2004, were matched to patients who stayed and were treated (N=1,476 pairs) according to registration date and time (+/-2 hours) and triage level (controls). The association between sociodemographic characteristics, previous ED utilization, and proximity to the ED and the risk of an uncompleted visit was assessed by the odds ratio (OR) using conditional logistic regression. RESULTS: During the 6-month study period, the overall left-without-being-seen rate was 6.4%. Seventeen percent of cases compared with 5% of controls had at least 1 previous uncompleted visit during the previous year. After adjusting for all patient characteristics, younger age, being uninsured (adjusted OR=1.73; 95% confidence interval [CI] 1.35 to 2.21) or covered by Medicaid (adjusted OR=1.67; 95% CI 1.27 to 2.20), and a previous uncompleted visit (adjusted OR=3.60; 95% CI 2.67 to 4.85) were significantly associated with the risk of an uncompleted visit. CONCLUSION: Previous ED utilization is predictive of future ED utilization. EDs should make every effort to keep their left-without-being-seen rates to a minimum because patients who are the least likely to receive care elsewhere (ie, those uninsured or covered by Medicaid) are more likely to leave without being seen.

Adolescent↗

Genetic restoration of aldose reductase to the collecting tubules restores maturation of the urine concentrating mechanism.

To investigate the underlying causes for aldose reductase deficiency-induced diabetes insipidus, we carried out studies with three genotypic groups of mice. These included wild-type mice, knockout mice, and a newly created bitransgenic line that was homozygous for both the aldose reductase null mutation and an aldose reductase knockin transgene driven by the kidney-specific cadherin promoter to direct transgene expression in the collecting tubule epithelial cells. We found that from early renal developmental stages onward, urine osmolality did not exceed 1,000 mosmol/kgH2O in aldose reductase-deficient mice. The functional defects were correlated with significant renal cellular and structural abnormalities that included cell shrinkage, apoptosis, disorganized tubular and vascular structures, and segmental atrophy. In contrast, the transgenic aldose reductase expression in the bitransgenic mice largely but incompletely rescued urine concentrating capacity and significantly improved renal cell survival, cellular morphology, and renal structures. Together, these results suggest that aldose reductase not only plays important roles in osmoregulation and medullary cell survival but may also be essential for the full maturation of the urine concentrating mechanism.

Aldehyde Reductase↗

Adsorption mechanism at the molecular level between polymers and uremic octapeptide by the 2D 1H NMR Technique.

To remove uremic octapeptide from the blood stream of uremic patients, various modified polyacylamide cross-linked absorbents were prepared. Adsorption experiments showed these absorbents have significant differences in adsorption capacity to the target peptide. In this paper, two-dimension proton nuclear magnetic resonance (2D 1H NMR) spectroscopy was used to investigate the interaction mechanism between the peptide and the adsorbents. Because of the insolubility of the absorbent, some soluble linear polymers with the same functional groups as the absorbents were employed as the model adsorbents in 2D 1H NMR. The preferred binding site for the peptide and polymers was identified to be at the C-terminal carboxyl group of the octapeptide via chemical shift perturbation effects. In this study, we found that hydrogen bonding, electrostatic, and hydrophobic interactions all play a role in the interaction force but had different contributions. Especially, the great chemical shift changes of the aromatic amino acid residues (Trp) during the interaction between butyl-modified polyacrylamide and octapeptide suggested the hydrophobic interaction, incorporated with the electrostatic force, played an important role in the binding reaction in aqueous solutions. This information not only rationally explained the results of the adsorption experiments, but also identified the effective binding site and mechanism, and shall provide a structural basis for designing better affinity-type adsorbents for the target peptide.

Adsorption↗

Graduated driver licensing programs and fatal crashes of 16-year-old drivers: a national evaluation.

CONTEXT: Implementation of graduated driver licensing programs is associated with reductions in crash rates of young drivers, but graduated driver licensing programs vary in their components. The impact of programs with different components is unknown. OBJECTIVE: The purpose of this work was to determine which graduated driver licensing programs are associated with the greatest reductions in fatal motor vehicle crashes involving 16-year-old drivers. METHODS: We conducted a retrospective study of all 16-year-old drivers involved in fatal crashes in the United States from 1994 through 2004 using data from the Fatality Analysis Reporting System and the US Census Bureau. We measured incidence rate ratios of fatal motor vehicle crashes involving 16-year-old drivers according to graduated driver licensing programs, adjusted for state and year. RESULTS: Compared with state quarters with no graduated driver licensing program components, reductions of 16% to 21% in fatal crash involvement rates of 16-year-old drivers occurred with programs that included > or = 3-month mandatory waiting period, nighttime driving restriction, and either > or = 30 hours of supervised driving or passenger restriction. Reductions of 18% to 21% occurred in state quarters with programs that included > or = 5 of the 7 components examined. Drivers aged 20 to 24 or 25 to 29 years did not experience significant reductions. CONCLUSION: Comprehensive graduated driver licensing programs are associated with reductions of approximately 20% in 16-year-old drivers' fatal crash involvement rates. The greatest benefit seems to be associated with programs that include age requirements and > or = 3 months of waiting before the intermediate stage, nighttime driving restriction, and either > or = 30 hours of supervised driving or passenger restriction.

Accidents, Traffic↗

[Different types of tissue transplantation in repairing tissue defects and function reconstruction].

OBJECTIVE: To explore the clinical effect of different types of free tissue transplantation on repairing tissue defects and reconstructing functions. METHODS: From November 2001 to September 2004, 14 types of free tissue transplantation and 78 free tissue flaps were applied to repairing tissue defects and reconstructing functions in extremities and maxillofacial region in 69 cases. Of the 69 cases, there were 53 males and 16 females (their ages ranged from 18 to 56, 31 on average). Five cases were repaired because of skin defects in foot, 22 cases were repaired because of skin defects in leg, 36 cases were repaired as the result of skin defects in hand or forearm and finger reconstruction, 3 cases were restored by virtue of ulna or radius defects, and 3 cases were repaired in maxillofacial region. There were 55 cases of open wound, in which 16 cases were infectious wound, 6 cases were osteomyelitis or pyogenic arthritis. There were 14 cases of non-infectious wound. The area of these tissue flaps ranged from 2.0 cm x 1.5 cm to 43.0 cm x 12.0 cm. The length of bone transplantation ranged from 10 cm to 15 cm. RESULTS: Arterial crisis occurred in 2 cases, venous crisis occurred in 2 cases. Seventy-six flaps survived completely and 2 flaps survived partially which were later healed. Fifty-two cases were healed at stage I, 13 cases were healed at stage I (healing time ranged from 20 to 30 days), purulent infection occurred to 4 cases(healing time ranged from 3 to 11 months). Bone healing time ranged from 6 to 8 weeks in finger reconstruction. Bone healing time ranged from 4 to 6 months in fibula transplantation. The function reconstruction and appearance were satisfying. The functions of all regions, where free tissues were supplied, were not disturbed. CONCLUSION: Tissue transplantation and composite tissue transplantation are effective in repairing tissue defects and reconstructing functions.

Adolescent↗

Pilot error in air carrier accidents: does age matter?

INTRODUCTION: The relationship between pilot age and safety performance has been the subject of research and controversy since the "Age 60 Rule" became effective in 1960. This study aimed to examine age-related differences in the prevalence and patterns of pilot error in air carrier accidents. METHODS: Investigation reports from the National Transportation Safety Board for accidents involving Part 121 operations in the United States between 1983 and 2002 were reviewed to identify pilot error and other contributing factors. Accident circumstances and the presence and type of pilot error were analyzed in relation to pilot age using Chi-square tests. RESULTS: Of the 558 air carrier accidents studied, 25% resulted from turbulence, 21% from mechanical failure, 16% from taxiing events, 13% from loss of control at landing or takeoff, and 25% from other causes. Accidents involving older pilots were more likely to be caused by turbulence, whereas accidents involving younger pilots were more likely to be taxiing events. Pilot error was a contributing factor in 34%, 38%, 35%, and 34% of the accidents involving pilots ages 25-34 yr, 35-44 yr, 45-54 yr, and 55-59 yr, respectively (p = 0.87). The patterns of pilot error were similar across age groups. Overall, 26% of the pilot errors identified were inattentiveness, 22% flawed decisions, 22% mishandled aircraft kinetics, and 11% poor crew interactions. CONCLUSION: The prevalence and patterns of pilot error in air carrier accidents do not seem to change with pilot age. The lack of association between pilot age and error may be due to the "safe worker effect" resulting from the rigorous selection processes and certification standards for professional pilots.

Accidents, Aviation↗

Pilot alcohol violations reported in U.S. newspapers, 1990-2006.

INTRODUCTION: Alcohol violations by airline pilots are rare yet remain a public concern. Such incidents often generate widespread news coverage. This study examines the frequency and characteristics of alcohol violation incidents involving airline pilots reported in U.S. newspapers. METHODS: The database of Lexis-Nexis, which contains full-text articles for over 350 newspapers, was searched to identify alcohol violation incidents involving airline pilots in the U.S. between January 1990 and June 2006. Information pertaining to the pilot, flight, blood alcohol concentration (BAC), and consequence was ascertained for each incident based on the newspaper coverage. RESULTS: During the study period, newspapers reported on a total of 13 incidents of alcohol violations involving 17 pilots. All but two of the incidents occurred during January 2002 through June 2006. The majority (85%) of the incidents were first identified by airport personnel, such as security screeners, based on suspicion of alcohol use by the pilot. Subsequent alcohol testing revealed a mean BAC of 90 mg/dL (ranging from 10 mg x dL(-1) to 182 mg x dL(-1)). Of the 17 pilots, 6 were known to be prosecuted criminally, including 5 who were sentenced to jail terms. DISCUSSION: Incidents of alcohol violations by airline pilots reported in U.S. newspapers have increased in recent years. This increase is likely due in part to increased detection resulting from enhanced aviation security and enforcement following the September 2001 terrorist attacks.

Aerospace Medicine↗

Epidemiologic patterns of injuries treated in ambulatory care settings.

STUDY OBJECTIVE: Epidemiologic studies of injury morbidity have relied primarily on data from emergency departments (EDs) and hospital admissions. We seek to assess the incidences and characteristics of acute injuries treated at EDs and other ambulatory care settings. METHODS: Using data from the 2002 National Health Care Survey on initial visits for acute injuries to EDs, physician offices, and hospital outpatient departments, we estimated the frequencies and incidence rates of medically attended injury by patient characteristics and care setting. RESULTS: In the United States in 2002, 76 million nonfatal acute injuries received initial medical attention at EDs (46.2%), physician offices (47.8%), and outpatient departments (6.0%). The overall annual incidence rate of medically attended injury was 26.8 per 100 population (95% confidence interval 24.4 to 29.7). Falls accounted for 16.7% of all medically attended injuries. Injury patients who were black or uninsured were significantly more likely to visit EDs than other care settings for treatment. More than 2.4 million (3.2%) injury patients were admitted to hospitals, 96.6% of them through EDs. CONCLUSION: Fewer than half of all medically attended acute injuries in the United States receive initial treatment in EDs. Injury severity and characteristics vary among care settings.

Adolescent↗

Correlating homicide and suicide.

BACKGROUND: The relationship between homicide and suicide has been studied extensively, but with conflicting results. The primary objective of this study was to examine the correlation between homicide and suicide rates in a large cross-sectional sample of UN member states. METHODS: The study used age-standardized data on homicide and suicide for 65 international locales compiled by the World Health Organization. Weighted correlation coefficients between homicide and suicide rates were computed by sex, income level, and geographic region. RESULTS: The overall correlation between homicide and suicide rates was weak and statistically insignificant (rho = -0.08, P = 0.5178). However, when analysed by geographic region the data revealed two distinct patterns: homicide and suicide rates were positively correlated in European countries (rho = 0.89, P < 0.0001), but negatively correlated in the Asia Pacific Region (rho = -0.97, P < 0.0001), and the Americas (rho = -0.62, P < 0.005). CONCLUSIONS: The strength and direction of the relationship between homicide and suicide vary significantly with geographic region. The divergent geographic patterns in the relationship between homicide and suicide might be due to regional differences in social and cultural variables.

Cross-Sectional Studies↗

Characteristics of alcohol-related fatal general aviation crashes.

BACKGROUND: The effects of alcohol on piloting performance have been studied extensively. Information describing alcohol-related aviation crashes, however, is scant. METHODS: We developed a data system for fatally injured pilots in Maryland, New Mexico, and North Carolina by linking autopsy data from the state medical examiner offices and crash investigation reports from the National Transportation Safety Board. Alcohol-related crashes are defined as those in which the pilot had a blood alcohol concentration of 20 mg/dL or greater. Differences between alcohol- and non-alcohol-related crashes were assessed with regard to pilot characteristics, crash circumstances, and human factors. RESULTS: The National Transportation Safety Board recorded 313 general aviation crashes fatal to the pilot in the three states between 1985 and 2000. Of these crashes, 255 (81%) were matched successfully with medical examiner records. Alcohol testing results were available for 233 of the fatally injured pilots. Of those tested for alcohol, 25 (11%) had blood alcohol concentrations > or =20 mg/dL (mean=75 +/- 64 mg/dL). The majority of alcohol-related crashes (52%) occurred at night (7p.m. to 6a.m.), compared with 28% of other crashes (P < 0.01). Alcohol-related crashes were significantly more likely than other crashes to have involved continued flight under visual flight rules (VFR) into instrument meteorological conditions (IMC) (32% versus 12%, P < 0.01), and flawed decisions (64% versus 41%, P = 0.03). CONCLUSIONS: Distinctive epidemiological patterns are exhibited in alcohol-related fatal general aviation crashes. Alcohol appears to play a particularly important role in crashes involving flight under VFR into IMC.

Accidents, Aviation↗

Driving-while-intoxicated history as a risk marker for general aviation pilots.

The Federal Aviation Administration conducts background checking for driving-while-intoxicated (DWI) convictions on all pilots. This study examined the association between DWI history and crash risk in a cohort of 335,672 general aviation pilots. These pilots were followed up from 1994 to 2000 through the aviation crash surveillance system of the National Transportation Safety Board. At baseline, 3.4% of the pilots had a DWI history. DWI history was associated with a 43% increased risk of crash involvement (adjusted relative risk: 1.43; 95% confidence interval: 1.15-1.77). The population-attributable risk fraction for DWI history was estimated as 1.4%. In addition to DWI history, male gender, older age, and inexperience were associated with significantly increased risk of crash involvement. The results of this study support DWI history as a valid risk marker for general aviation pilots. The safety benefit of background checking for DWI history needs to be further evaluated.

Adolescent↗

Drinking history and risk of fatal injury: comparison among specific injury causes.

The effect of acute alcohol use on injury risk is well documented, but the relationship between drinking history and fatal injury has not been adequately studied. The authors performed a case-control analysis to explore the association between drinking history and specific causes of fatal injury. Cases (n=5549) were persons who died from injury, selected from the 1993 National Mortality Followback Survey (NMFS); controls (n=42,698) were a representative sample of the general population, selected from the 1992 National Longitudinal Alcohol Epidemiologic Survey (NLAES). Current drinkers comprised 59% of the cases compared with 44% of the controls. After adjustment for age, sex, race/ethnicity, education, marital status, employment, and drug use, the odds ratio (OR) of dying from drowning for current drinkers was 3.48 (95% confidence interval (CI)=1.94, 6.25), the highest among all causes of injury studied. The lowest adjusted odds ratio associated with current drinking was for falls (OR=1.38; 95% CI=1.05, 1.82). Being a current drinker increased the risk of dying from suicide more for females (OR=4.04; 95% CI=1.64, 9.93) than for males (OR=1.45; 95% CI=1.20, 1.74). The authors conclude that drinking history is associated with a significantly increased risk of all types of fatal injury.

Adolescent↗

Body mass index and cardiovascular disease in a birth cohort of commuter air carrier and air taxi pilots.

PURPOSE: Acute cardiovascular events such as heart attack and stroke in commercial pilots have been a concern to flight safety. The purpose of this study was to examine the association of body mass index (BMI) with cardiovascular disease in commercial pilots. METHODS: We followed from 1987 to 1997 a cohort of 3019 male commuter and air taxi pilots who were born between 1933 and 1942 and who were certified by the US Federal Aviation Administration. The relationship between BMI and the risk of cardiovascular disease was assessed using Poisson regression modeling based on generalized estimation equations. RESULTS: At baseline, 55% of the pilots were overweight (25 kg/m(2) BMI < 30 kg/m(2)) and 7% were obese (BMI >/= 30 kg/m(2)). The follow-up accumulated a total of 20,671 person-years and 1897 diagnoses of cardiovascular disease, yielding an incidence rate of 92 per 1000 person-years. The incidence rates of cardiovascular disease increased significantly with BMI. With adjustment for baseline history of cardiovascular disease and age, pilots who were overweight and obese had 6% and 22% higher risk of cardiovascular disease, respectively, than their counterparts with normal BMI. CONCLUSIONS: The prevalence of overweight/obesity and the relationship between BMI and cardiovascular disease among commercial pilots parallel findings from the general population. Incorporating BMI into the current medical standards for commercial pilots merits serious consideration.

Aviation↗

Trends in Arkansas motorcycle trauma after helmet law repeal.

OBJECTIVES: This study aimed to assess the impact of the 1997 Arkansas helmet law repeal on motorcycle registrations, crash and fatality risks, and alcohol involvement in motorcycle crashes. METHODS: Annual motorcycle registration data for the years 1990 through 2001 were obtained from the Arkansas Department of Finance and Administration. These motorcycle registration data were complemented by the motorcycle crash data from the Arkansas State Police Highway Safety Office and motorcycle fatality data for the state of Arkansas from the Fatality Analysis Reporting System. The impact of the repeal on crash rates, helmet usage, and alcohol involvement was assessed through comparisons of data from before (1993 to 1996) and after (1998 to 2001) the repeal. RESULTS: After the repeal, an increase in motorcycle registrations correlated with a marked rise in the total number of crashes and fatalities; however, fatalities per crash remained virtually the same. The proportion of motorcycle fatalities that were not wearing a helmet increased from 47.0% (47/100) before the repeal to 78.2% (104/133) after the repeal (P = 0.001). The overall percentage of fatal motorcycle crashes involving alcohol use remained unchanged after the repeal (37.6% [29/77] to 38.5% [40/104], P = 0.91), but the percentage of fatal crashes involving drinking nonhelmeted drivers increased from 14.2% (11/77) to 33.6% (35/104) (P = 0.003). Inebriated motorcyclists killed in crashes were overwhelmingly non-helmeted (87.5%, 35/40) after the repeal, up from 37.9% (11/29) before the repeal (P < 0.001). CONCLUSIONS: These findings suggest that the repeal of the mandatory helmet law in Arkansas has had a significant adverse effect on road safety.

Accidents, Traffic↗

Synthesis and luminescence of ZnMgS:Mn2+ nanoparticles.

Efficient green emission from ZnMgS:Mn2+ nanoparticles prepared by co-doping Mg2+ and Mn2+ ions into ZnS lattices has been observed. The synthesis is carried out in aqueous solution, followed by a post-annealing process, thus showing the features of less complexity, low cost, and easy incorporation of dopants. In comparison with the emission of ZnS:Mn2+ nanoparticles, which is located generally around 590 nm, the photoluminescence of ZnMgS:Mn2+ nanoparticles is blue-shifted by 14 nm in wavelength, leading to the enhanced green emission. The X-ray diffraction, electron spin resonance, and pressure dependent photoluminescence measurements suggest that the change of the crystal field caused by Mg2+ ionic doping and the lower symmetry in the nanoparticles may account for the blue-shift of the photoluminescence. The ZnMgS:Mn2+ nanoparticles with 1% Mn2+ doping exhibit the strongest luminescence, which could potentially meet the requirements for the construction of green light emitting diodes.

Crystallization↗

Suicide by aircraft: a comparative analysis.

INTRODUCTION: Suicide is the 11 th leading cause of death in the United States. The objective of this study is to document the characteristics of aviation-related suicides and suicide attempts. METHODS: Aviation accidents reported by the National Transportation Safety Board between 1983 and 2003 were screened for cases in which suicide was listed as a probable cause. For each suicide case, two accidents were randomly selected as controls, matched on sex of pilot, type of flight, state, and year of occurrence. Mantel-Haenszel summary Chi-square tests were used to compare cases to controls. Conditional logistic regression modeling was performed to assess the association of pilot and flight characteristics with suicide-related crashes. RESULTS: During the 21-yr study period, 37 pilots committed or attempted suicide by aircraft, with 36 resulting in at least one fatality. All the cases were men and involved general aviation flights. Toxicological test results revealed that 24% of the cases had used alcohol and 14% had used other illicit drugs. Underlying factors included domestic and social problems (46%), legal trouble (40%), and pre-existing psychiatric conditions (38%). Compared with controls, suicide cases involved younger pilots (p < 0.05), were less likely to have another occupant (p < 0.0001), were more destructive to the aircraft (p < 0.0001), and were more likely to have occurred away from the airport (p < 0.0001). CONCLUSION: Aviation crashes caused by suicide differ from unintentional aviation accidents in pilot characteristics, crash circumstances, and outcomes.

Accidents, Aviation↗

Ground crew injuries and fatalities in U.S. commercial aviation, 1983-2004.

INTRODUCTION: Ground crew services are an essential part of airport operations. Injury hazards to ground crewmembers who are in close proximity to aircraft have not been well studied. The objective of this paper was to examine airport ground crew injuries and fatalities involving aircraft of commuter air carriers and major airlines. METHODS: Investigation reports for all ground crew injuries involving commuter and major airline aircraft that occurred at United States airports between 1983 and 2004 were obtained from the National Transportation Safety Board (NTSB) and analyzed to describe the immediate cause and pattern of injury occurrence. RESULTS: During the 22-yr study period, the NTSB recorded a total of 80 ground crew accidents involving landing, taxiing, or standing commercial airline aircraft, yielding an overall rate of 0.47 ground crew related accidents per 1 million aircraft departures. These accidents resulted in injuries to 98 ground crewmembers, including 21 fatalities. Two-thirds of the accidents took place as the aircraft was departing. Vehicular collisions with an aircraft made up 43% of accidents, 34% were caused by moving aircraft equipment such as propellers or nose gear, and 11% resulted from jet blasts or fires. CONCLUSIONS: intervention programs for airport ground personnel should emphasize the safe operation of the aircraft equipment and ground vehicles. Some of the injuries to ground crewmembers might be avoided through improved design of commonly used equipment.

Accidents, Aviation↗