Biomedical subjects

Gary J Badger

Publications and source records attributed to Gary J Badger.

36 records · Page 2Linked to original sources

PubMed2004

An experimental test of the influence of prior cigarette smoking abstinence on future abstinence.

Significant positive associations between early and later abstinence are often reported in clinical trials on smoking cessation, but those relationships do not permit causal inferences. The present study was conducted to examine experimentally whether prior smoking abstinence histories can directly facilitate later abstinence, using a contingency management procedure to manipulate prior abstinence. A total of 40 adult cigarette smokers who were not trying to quit were randomly assigned to one of two conditions: Contingent ALL (C-ALL), who earned monetary incentives contingent on smoking abstinence during three 5 day experimental periods; or Contingent LAST (C-LAST), who earned incentives independent of abstinence during the first two periods (i.e., noncontingent payments) and contingent on abstinence during the final period. The contingency management procedure was effective in establishing different abstinence histories in the two conditions during the first two periods. Comparison of abstinence levels between the C-ALL and C-LAST conditions during the third period showed significantly greater abstinence in the C-ALL condition, although nicotine withdrawal and other subject ratings generally did not differ significantly between the two conditions. These results provide experimental evidence that prior abstinence histories can directly influence subsequent efforts to abstain from smoking.

Adolescent↗

PubMed2004

A pilot study on voucher-based incentives to promote abstinence from cigarette smoking during pregnancy and postpartum.

We report results from a pilot study examining the use of vouchers redeemable for retail items as incentives for smoking cessation during pregnancy and postpartum. Of 100 study-eligible women who were still smoking upon entering prenatal care, 58 were recruited from university-based and community obstetric practices to participate in a smoking cessation study. Participants were assigned to either contingent or noncontingent voucher conditions. Vouchers were available during pregnancy and for 12 weeks postpartum. In the contingent condition, vouchers were earned for biochemically verified smoking abstinence. In the noncontingent condition, vouchers were earned independent of smoking status. Abstinence monitoring and associated voucher delivery was conducted daily during the initial 5 days of the cessation effort, gradually decreased to every other week antepartum, increased to once weekly during the initial 4 weeks postpartum, and then decreased again to every other week for the remaining 8 weeks of the postpartum intervention period. Contingent vouchers increased 7-day point-prevalence abstinence at the end-of-pregnancy (37% vs. 9%) and 12-week postpartum (33% vs. 0%) assessments. That effect was sustained through the 24-week postpartum assessment (27% vs. 0%), which was 12 weeks after discontinuation of the voucher program. Total mean voucher earnings across antepartum and postpartum were 397 US dollars (SD=414 US dollars) and 313 US dollars (SD=142 dollars) in the contingent and noncontingent conditions, respectively. The magnitude of these treatment effects exceed levels typically observed with pregnant and recently postpartum smokers, and the maintenance of effects through 24 weeks postpartum extends the duration beyond those reported previously.

Adult↗

PubMed2004

Yin scores and yang scores: A new method for quantitative diagnostic evaluation in traditional Chinese medicine research.

OBJECTIVE: To develop and evaluate a method for quantitative evaluation of yin and yang (yin and yang scores) in human subjects for the purposes of research. This method aims to classify subjects into groups allowing future quantitative testing of key research questions such as: do different groups of patients respond differently to acupuncture treatments or Chinese herb formulas? METHODS: In a pilot study of inter-rater reliability, 12 volunteers were each successively interviewed and examined by 6 acupuncturists on the same day. Each acupuncturist gave each volunteer a score for yin and a score for yang on a scale of -10 to +10, zero representing a "balanced" score. Acupuncturists were blinded to each other's scores. RESULTS: Overall mean (+/-standard deviation [SD]) yin and yang scores were -1.86 +/- 0.90 and -0.68 +/- 1.23 respectively. Intraclass correlations (ICCs) associated with a single acupuncturist's ratings were 0.35 (yin) and 0.36 (yang). ICC's for subject's mean scores based on the six acupuncturists were 0.77 (yin) and 0.78 (yang). Significant differences in mean scores across subjects were detected for yin (p < 0.001) and yang (p < 0.001) (repeated-measures analysis of variance [ANOVA]) based on the multiple acupuncturists' ratings. CONCLUSION: These results indicate that (1) yin and yang can be quantified in a reliable manner, but evaluation by multiple acupuncturists is necessary to obtain a reliable score; (2) yin and yang scores can be used to group individuals for the purposes of statistical analysis. Further evaluation of yin and yang scores in a greater number and wider variety of patients will be needed to evaluate the potential usefulness of this measurement tool in acupuncture clinical trials and basic physiologic research.

Acupuncture↗

PubMed2004

Risk-sensitive foraging theory elucidates risky choices made by heroin addicts.

AIM: The behavioral process of risk-sensitive foraging (RSF) specifies that the level of satiation or deprivation determines choice between a constant and variable quantity of food. Specifically, RSF stipulates that organisms experiencing satiation and deprivation prefer constant (risk-averse) and variable (risk-prone) choices, respectively. The relevance of this behavioral process to risky choices of opioid-dependent patients is examined in this study. METHODS: Thirty adult opioid-dependent out-patients made hypothetical choices between constant and variable heroin sources with equivalent means. Preferences for constant (e.g. three bags of heroin) and variable heroin sources (e.g. on average produces three bags of heroin, but vary from one to five bags of heroin on any instance) were assessed using questionnaires that manipulated the amount, delay to receipt and drug potency of heroin across approximately 20 levels. Subjects made choices between constant and variable options after hearing scripts describing the signs and symptoms of opioid satiation and opioid deprivation. RESULTS: Consistent with the prediction of RSF, subjects purchased significantly more hypothetical heroin from a variable source when exposed to an opioid-deprived script than an opioid-satiated script. This pattern was observed across manipulations of heroin amount, delay to receipt of heroin and heroin potency. Selection of the variable option increased as a function of magnitude under the deprived conditions. The selection of the variable option generally did not increase as a function of magnitude under the satiated conditions except when delay to heroin delivery increased. As delay increased, selection of the variable option increased under the satiated script, but at a lower level observed with the deprived script. CONCLUSIONS: These data suggest that risky choices of heroin-dependent individuals can be understood and predicted with the application of RSF theory. This research suggests that an evolutionarily old behavioral process may contribute to the risky behavior of the drug-dependent.

Adult↗

PubMed2004

Marginal increase in cost and excess length of stay associated with nosocomial bloodstream infections in surviving very low birth weight infants.

OBJECTIVE: Nosocomial bloodstream infections (NBIs) are associated with serious morbidity and prolonged length of stay (LOS) in very low birth weight (VLBW) infants. However, the marginal costs and excess LOS associated with these infections have never been measured in different birth weight (BW) categories after adjustment for many of the potentially confounding demographic variables, comorbidities, and treatments. The objective of this study was to measure the marginal cost and excess LOS caused by NBIs in surviving VLBW infants in different BW categories. METHODS: This retrospective study examined data previously collected as part of the Neonatal Intensive Care Quality Improvement Collaborative 2000 and the Vermont Oxford Network clinical outcomes database. Univariate analyses and multiple regression were used to examine the effect of NBIs on hospital costs and LOS. Seventeen neonatal intensive care units that participated in the Neonatal Intensive Care Quality Improvement Collaborative 2000 submitted both clinical and financial data on their VLBW infants who were born from January 1, 1998, to December 31, 1999. This study included data from both university and community hospitals. RESULTS: NBIs occurred in 19.7% of 2809 patients included in this study. NBI was associated with significantly increased treatment costs for infants with BW 751 to 1500 g. The marginal costs of NBIs, as estimated by multiple regression, varied from 5875 dollars for VLBW infants with a BW of 401 to 750 g to 12,80 dollars for those with BW of 751 to 1000 g. LOS was significantly increased in all BW categories. The excess LOS estimated by multiple regression varied from 4 days in VLBW infants with a BW of 1001 to 1251 g to 7 days in those with a BW of 751 to 1000 g. CONCLUSIONS: NBIs are associated with increased hospital treatment costs and LOS but by varying amounts depending on the BW. Preventing a single NBI could reduce the treatment costs of a VLBW infant by at least several thousand dollars. These savings are a greater percentage of the total treatment costs in VLBW infants with BW 1001 to 1500 g than in smaller infants.

Analysis of Variance↗

PubMed2003

Acute effects of D-amphetamine on progressive-ratio performance maintained by cigarette smoking and money.

RATIONALE: Psychomotor stimulants often increase cigarette smoking, although the mechanisms responsible for that effect remain unclear. OBJECTIVE: The present study was conducted to extend our investigation of the effects of psychomotor stimulant use on the reinforcing effects of cigarette smoking. METHODS: A progressive-ratio (PR) schedule was used to examine the acute effects of orally administered D-amphetamine (placebo, 5, 10, 15 mg/70 kg) on the reinforcing effects of smoking (2 puffs/ratio) and money (1.00 US dollar/ratio) in 18 adult smokers. RESULTS: Among the overall sample of 18 smokers, D-amphetamine produced only a modest, non-significant increase in the amount of responding maintained by smoking (PR break point), but effects varied systematically between subjects. D-Amphetamine increased the smoking break point among ten subjects (responders), while leaving unchanged or decreasing the break point in the remaining eight individuals (non-responders). Responders also were more sensitive than non-responders to d-amphetamine's effects on visual-analog ratings of "high", "good effects", "drowsy", and "slurred speech", but not on other subject ratings (i.e., "bad effects", "jittery", "confused") or on any physiological measures (i.e., heart rate, blood pressure, skin temperature). D-Amphetamine did not significantly alter PR break point maintained by money. CONCLUSIONS: These results provide further evidence that D-amphetamine can increase the reinforcing effects of cigarette smoking, at least among a subset of smokers.

Adult↗

PubMed2003

Community reinforcement therapy for cocaine-dependent outpatients.

OBJECTIVE: To examine the contributions of community reinforcement therapy to outcome in the community reinforcement approach (CRA) + vouchers outpatient treatment for cocaine dependence. METHODS: One hundred cocaine-dependent outpatients were randomly assigned to one of 2 treatment conditions: CRA + vouchers or vouchers only. All patients earned incentives in the form of vouchers exchangeable for retail items contingent on cocaine-free urinalysis results during treatment weeks 1 to 12. Incentives were combined with a 24-week course of CRA therapy designed to promote healthy lifestyle changes in the CRA + vouchers condition, while incentives represented the primary treatment in the vouchers-only condition. Patient drug use and psychosocial functioning were assessed at intake and at least every 3 months for 2 years after treatment entry. RESULTS: Patients treated with CRA + vouchers were retained better in treatment, used cocaine at a lower frequency during treatment but not follow-up, and reported a lower frequency of drinking to intoxication during treatment and follow-up compared with patients treated with vouchers only. Patients treated with CRA + vouchers also reported a higher frequency of days of paid employment during treatment and the initial 6 months of follow-up, decreased depressive symptoms during treatment only, and fewer hospitalizations and legal problems during follow-up. CONCLUSIONS: Combining CRA with vouchers had therapeutic effects on substance abuse and psychosocial functioning during treatment and posttreatment follow-up in cocaine-dependent outpatients, although effects on cocaine use appear to be limited to the treatment period.

Adult↗

PubMed2003

A contingent payment model of smoking cessation: effects on abstinence and withdrawal.

The present study was designed to characterize nicotine withdrawal during a 5-day period in which smokers who were not trying to quit were offered monetary incentives to abstain while residing in their usual environments. Participants were randomly assigned to one of three groups. In two groups, monetary payment was delivered contingent on breath carbon monoxide levels (CO< or =8 ppm) indicating recent smoking abstinence, with the amount of payment differing between the two groups. The third group was a control group in which payment was delivered independent of smoking status. Participants provided CO samples three times per day (morning, afternoon- and evening) for 5 days (Monday-Friday). At each evening visit, all participants completed a nicotine withdrawal questionnaire and other questionnaires. Contingent payment significantly decreased expired-air CO and salivary cotinine levels as compared with the control group. No significant differences in abstinence were noted as a function of the amount paid. Participants in both contingent payment groups reported significantly more withdrawal symptoms than those in the noncontingent control group, including increases in anxiety and nervousness, impatience and restlessness, hunger, and desire to smoke. Such contingent payment procedures may provide an effective method for studying nicotine withdrawal in smokers that does not require the costly and inconvenient practice of housing research participants on a closed ward to prevent smoking.

Adolescent↗

PubMed2002

Mild opioid deprivation increases the degree that opioid-dependent outpatients discount delayed heroin and money.

RATIONALE: A growing literature suggests that excessive temporal discounting of delayed rewards may be a contributing factor in the etiology of substance abuse problems. Little is known, however, about how drug deprivation may affect temporal discounting of delayed rewards by drug-dependent individuals. OBJECTIVE: To examine the extent to which opioid deprivation affects how opioid-dependent individuals discount small, medium and large quantities of delayed heroin and money. METHODS: Thirteen opioid-dependent individuals maintained on buprenorphine completed a hypothetical choice task in which they choose between a constant delayed reward amount and an immediate reward amount that was adjusted until they expressed indifference between both outcomes. The task was completed for three values of heroin and money rewards during eight sessions under conditions of opioid deprivation (four sessions) and satiation (four sessions). RESULTS: Across conditions, hyperbolic functions provided a good fit for the discounting data. Degree of discounting was significantly higher when subjects were opioid deprived. Consistent with previous findings, degree of discounting was higher for heroin than money and inversely related to the magnitude of the reward. CONCLUSION: Opioid deprivation increased the degree to which dependent individuals discounted delayed heroin and money. Understanding the conditions that affect how drug-dependent individuals discount delayed rewards might help us understand the myopic choices made by such individuals and help improve treatment outcomes.

Adult↗

PubMed2002

Evidence of connective tissue involvement in acupuncture.

Acupuncture needle manipulation gives rise to "needle grasp," a biomechanical phenomenon characterized by an increase in the force necessary to pull the needle out of the tissue (pullout force). This study investigates the hypothesis that winding of connective tissue, rather than muscle contraction, is the mechanism responsible for needle grasp. We performed 1) measurements of pullout force in humans with and without needle penetration of muscle; 2) measurements of pullout force in anesthetized rats, with and without needle rotation, followed by measurements of connective tissue volume surrounding the needle; 3) imaging of rat abdominal wall explants, with and without needle rotation, using ultrasound scanning acoustic microscopy. We found 1) no evidence that increased penetration of muscle results in greater pullout force than increased penetration of subcutaneous tissue; 2) that both pullout force and subcutaneous tissue volume were increased by needle rotation; 3) that increased periodic architectural order was present in subcutaneous tissue with rotation, compared with no rotation. These data support connective tissue winding as the mechanism responsible for the increase in pullout force induced by needle rotation. Winding may allow needle movements to deliver a mechanical signal into the tissue and may be key to acupuncture's therapeutic mechanism.

Acupuncture↗

PubMed2002

Uterine artery hemodynamic adaptations through the menstrual cycle into early pregnancy.

OBJECTIVE: To estimate the time course of human uterine artery vascular adaptation through the menstrual cycle into early pregnancy. METHODS: We prospectively measured the uterine artery pulsatility index, peak systolic velocity, and volumetric blood flow during the menstrual cycle and at 4, 6, and 12 weeks of pregnancy in women who conceived. Upper extremity radial artery hemodynamic changes were examined as a control vessel. Ten subjects conceived within 12 months of menstrual cycle studies. Analyses were performed using repeated measures analysis of variance with P <.05 accepted for significance. RESULTS: In women who conceived, uterine artery peak systolic velocity demonstrated a significant increase during the period of observation, which began after cycle day 10 (0.36 x 0.02 meters per second) of the menstrual cycle and continued though 12 menstrual weeks (1.05 +/- 0.10 meters per second, P <.001). Uterine artery pulsatility index decreased significantly during the observation window from 3.0 +/- 0.2 in the follicular phase to 1.6 +/- 0.2 at 12 menstrual weeks (P <.001). Blood flow in the uterine artery increased significantly from cycle day 10 (22.2 +/- 1.8 mL per minute) to 12 menstrual weeks' gestation (150.2 +/- 40.3 mL per minute, P <.001). These patterns were significantly different from the patterns observed for the radial artery. CONCLUSION: Uterine artery hemodynamic adaptation in early pregnancy follows a continuum established during the menstrual cycle. These adaptations result in decreased uterine artery impedance and increased blood flow. These changes differ from those observed in the upper extremity radial artery (control vessel) suggesting independence of regional pelvic and systemic hemodynamic adaptations.

Adaptation, Physiological↗

PubMed2002

Measurement of anterior-posterior knee laxity: a comparison of three techniques.

Several non-invasive techniques have been developed to assess anterior-posterior (A-P) laxity of the knee, however, their accuracy remains unclear. Roentgen Stereophotogrammetry Analysis (RSA) is a three-dimensional motion analysis method that has been shown to be an accurate tool for evaluating joint kinematics. Thus. RSA provides a means that can be used to evaluate other less invasive techniques. The objectives of this study were to compare A-P laxity values as measured using the KT-1000 Knee Arthrometer, planar stress radiography and RSA, and to determine if they detect similar changes in A-P laxity over time in 15 subjects following anterior cruciate ligament reconstruction with patellar tendon autografts. The A-P laxity values of the injured knee were measured immediately following surgery and at their 3-, 6-, and 12-month follow-up visits. A-P laxity was defined as the A-P translation of the tibia relative to the femur that occurred between the posterior and anterior shear load limits of -90 to +130 N, respectively. The values of A-P laxity across all time points were 11.4 +/- 3.0, 10.2 +/- 3.3, and 6.9 +/- 3.0 mm (mean +/- standard deviation) for the KT-1000, planar stress radiography and the RSA methods, respectively. These values were significantly different from each other (p < 0.001). The two-dimensional analyses techniques (planar stress radiography and the KT-1000) consistently over-estimated the true laxity values that were obtained using the three-dimensional RSA technique. Significant increases in A-P laxity values over time were also detected with the KT-1000 (p = 0.04) and the RSA technique (p = 0.04). However, this increase was not evident when using planar stress radiography (p = 0.89). This study determined that the KT-1000 and RSA document temporal changes in A-P laxity following ACL reconstruction that were not documented by planar stress radiography.

Adult↗

PubMed2002

Examining possible gender differences among cocaine-dependent outpatients.

Potential differences in sociodemographics, drug use, and measures of treatment outcome were examined among 137 male and 51 female cocaine-dependent outpatients. More women than men were unemployed, received public assistance, and were living with their children. Women reported fewer years of regular cocaine use, spending less money per week on cocaine, less prior treatment for cocaine abuse, and were more likely than men to test positive for cocaine at intake. With respect to other drug use, fewer women than men reported using sedatives and tested positive for sedatives at intake. Women reported a lower frequency of alcohol use before intake, and fewer women than men met criteria for cannabis dependence. Men and women experienced comparable improvement during the course of treatment and follow-up.

Adult↗

PubMed2002

A simple mathematical modification of TRISS markedly improves calibration.

BACKGROUND: TRISS has reigned as the preeminent trauma outcome prediction model for 20 years. Despite this endorsement, the calibration of TRISS has been poor in most data sets where it has been examined. We hypothesized that the lack of calibration of TRISS was because of the inappropriate mathematical specification of the model that TRISS is based on, rather than the predictors in the model. In particular, we hypothesized that the nonlinearity of the Injury Severity Score (ISS) in the log odds of death was responsible for the poor calibration of TRISS, and further, that this nonlinearity could be corrected by the simple addition of an ISS squared term to the TRISS model. METHODS: We examined ISS in the log odds of mortality for linearity in one large trauma data set, the National Pediatric Trauma Registry (NPTR) (n = 53,113 from 1985-1996; mortality, 1.3%); and two small data sets, the University of New Mexico (UNM) (n = 3,142 from 1991-1995; mortality, 8.6%) and Portland, Oregon (PORT) (n = 2,916 from 1990-1994; mortality, 1.75%). In addition, in the NPTR we compared the calibration of TRISS models with and without linearity in the log odds of death. RESULTS: In the NPTR, ISS was profoundly nonlinear in the log odds of death for both blunt and penetrating trauma (p < 0.001). Moreover, the overall calibration of the TRISS model for the NPTR data was significantly improved when the nonlinearity of ISS was corrected by the addition of a quadratic ISS term as demonstrated by a 70% reduction (improvement) in the Hosmer-Lemeshow statistic. Interestingly, the addition of the ISS squared term did not affect the discrimination of the model. The log odds of survival in the UNM and PORT data sets were also better modeled when an ISS squared term was added (UNM, p = 0 0.052; PORT, p = 0.014), but improvements in the Hosmer-Lemeshow statistic were smaller, possibly because of the small size of these data sets. CONCLUSION: The TRISS model for outcome prediction currently uses ISS in a mathematically inappropriate way that impairs the calibration, but not the discrimination, of its predictions. If TRISS is to continue as the prediction standard for trauma, a quadratic ISS term must be added to the model. In the future, outcome prediction models should undergo thorough statistical modeling and evaluation before being released. Injury severity descriptors other than ISS (such as ASCOT, ICISS, or NISS) may require other modeling techniques to optimize the calibration of survival models that use these injury scores.

Adolescent↗

PubMed2002

Concurrent and retrospective reports of alcohol consumption across 30, 90 and 366 days: interactive voice response compared with the timeline follow back.

OBJECTIVE: To compare near-concurrent and retrospective reports of alcohol consumption and to determine whether a simple adjustment function could be applied to the retrospective reports to correct any distortions in reporting. METHOD: Reports of daily alcohol consumption collected via an Interactive Voice Response (IVR) system were aggregated over 30, 90 and 366 days and compared with the corresponding retrospective reports gathered with the Timeline Follow Back (TLFB). Comparisons of the IVR and TLFB reports for five consumption variables were made for each time period for 33 men. RESULTS: Significant differences between reporting methods were found for four of the five variables tested. On average, the TLFB yielded an underestimate of alcohol consumption compared to the IVR. This underestimate associated with TLFB reports was not dependent on the length of the recall period. Regression analyses indicated that the relationship between the two modalities of reporting was dependent on the quantity of drinks reported, thus precluding the application of a simple, linear metric to the TLFB data to model near real-time daily data obtained through the IVR more accurately. CONCLUSIONS: The retrospective TLFB consistently and significantly underestimated alcohol consumption compared to the aggregated daily reports. This underestimate, however, was stable across the three reporting periods. With one exception, no simple linear function could be applied to the retrospective TLFB consumption reports to more accurately reflect the IVR data gathered daily. Evidence presented here also suggests that underreporting on the TLFB is not simply a matter of consciously attempting to conceal consumption.

Adult↗

PubMed2002

Decline in alcohol consumption during two years of daily reporting.

OBJECTIVE: We conducted a formal analysis of the potential effects on alcohol consumption of daily reports to an Interactive Voice Response (IVR) system over a 2-year period. METHOD: Thirty-three white men who had been recruited from bars were invited to call a toll-free number daily to answer a 2-minute questionnaire regarding alcohol consumption the previous day, reasons for drinking or not drinking, mood and stress levels, and a few other relevant items. A recorded voice asked the questions and callers responded using the telephone keypad. During the 2-year study, all subjects were personally interviewed each quarter, including regular Timeline Follow Back (TLFB) assessments. We compared mean consumption levels reported for the first year with those reported the second year. RESULTS: Although there were consistent seasonal variations and holiday peaks, reported consumption declined over the 2 years of study. A comparison of average consumption across all subjects revealed significant declines in drinks per day, drinking days per week, and drinks per drinking day. Analysis of individuals showed at least some reduction in 82% of the subjects and statistically significant reductions in 45%. There was an estimated 19% reduction in consumption from Year I to Year 2 based on the IVR reports and a 21% reduction as ascertained by the TLFB. No significant changes were observed in nonalcohol-related measures. CONCLUSIONS: After exploring possible reasons for our results, we conclude that the most likely explanation of the decline in alcohol consumption is a reactivity effect due to reporting consumption regularly. The results suggest that IVR may have potential utility as an intervention for excessive alcohol consumption.

Adult↗

PubMed2002

Trends in mortality and morbidity for very low birth weight infants, 1991-1999.

BACKGROUND: Medical care for very low birth weight (VLBW) infants and their mothers has changed dramatically during the 1990s, yet it is unclear how these changes have affected mortality and morbidity. OBJECTIVE: We used the Vermont Oxford Network Database to identify trends in clinical practice and patient outcomes for VLBW infants born from 1991 to 1999. METHODS: Logistic regression was used to evaluate temporal trends in practices and outcomes while adjusting for patient characteristics and accounting for clustering of cases within hospitals. RESULTS: There were 118 448 infants 501 to 1500 g from 362 neonatal intensive care units enrolled in the Network Database from 1991 to 1999. Prenatal care, cesarean section, multiple births, antenatal steroids, and 1-minute Apgar scores increased during this period, as did the use of nasal continuous positive airway pressure, high-frequency ventilation, surfactant, and postnatal steroids. The proportion of white infants decreased; the proportions of Hispanic infants and those of other races increased. The crude and adjusted rates of mortality, pneumothorax, intraventricular hemorrhage (IVH), and severe IVH declined from 1991 to 1995, whereas from 1995 to 1999, the rates of mortality, IVH, and severe IVH did not change significantly, and pneumothorax increased. CONCLUSIONS: There have been major changes in both obstetric and neonatal care during the 1990s. These changes were associated with decreases in mortality and morbidity for VLBW infants during the first half of the decade. However, since 1995, no additional improvements in mortality or morbidity have been seen, ending a decades-long trend of improving outcomes for these infants.

Female↗

PubMedDate not supplied

The effects of compressive load and knee joint torque on peak anterior cruciate ligament strains.

BACKGROUND: High graft strains incurred during rehabilitation after anterior cruciate ligament reconstruction may be minimized if an external compressive load is simultaneously applied to the joint during closed kinetic chain exercises. HYPOTHESES: Peak anterior cruciate ligament strains will 1). increase with an increase in resistance torque during an exercise that involves concentric contraction of the extensor mechanism, 2). decrease with an increase in resistance torque during an exercise that involves concentric contraction of the flexors, and 3). decrease when an external compressive load is applied to the knee during both exercises relative to the no external compressive load condition. STUDY DESIGN: Controlled laboratory study. METHODS: Strains in the anteromedial bundle were measured in 10 subjects with normal ligaments. Flexor and extensor exercises were performed against controlled resistance torques with and without a compressive load applied to the foot. RESULTS: An increase in resistance produced an increase in peak anterior cruciate ligament strain for the extensor exercise with no compressive load applied. During the flexor exercise without a compressive load, an increase in resistance produced a decrease in peak strains. During the extensor exercise, the peak anterior cruciate ligament strain was not reduced with the application of the external compressive force. CONCLUSIONS: Extensor and flexor exercises that incorporate an external compressive load do not shield the anterior cruciate ligament from strain. However, no additional increase in strain occurs with an increase in resistance when the external compressive load is applied. Thus, it may be possible to increase the activity of the quadriceps muscles without increasing the strain by applying a compressive load (as with closed kinetic chain exercises).

Adult↗