Understanding the burden of traumatic injuries at the United States-Mexico border: A scoping review of the literature

ABSTRACT

The US-Mexico border is the busiest land crossing in the world and faces continuously increasing numbers of undocumented border crossers. Significant barriers to crossing are present in many regions of the border, including walls, bridges, rivers, canals, and the desert, each with unique features that can cause traumatic injury. The number of patients injured attempting to cross the border is also increasing, but significant knowledge gaps regarding these injuries and their impacts remain. The purpose of this scoping literature review is to describe the current state of trauma related to the US-Mexico border to draw attention to the problem, identify knowledge gaps in the existing literature, and introduce the creation of a consortium made up of representatives from border trauma centers in the Southwestern United States, the Border Region Doing Research on Trauma Consortium. Consortium members will collaborate to produce multicenter up-to-date data on the medical impact of the US-Mexico border, helping to elucidate the true magnitude of the problem and shed light on the impact cross-border trauma has on migrants, their families, and the US health care system. Only once the problem is fully described can meaningful solutions be provided.

Up and over: Consequences of raising the United States-Mexico border wall height

OBJECTIVES

San Diego County's geographic location lends a unique demographic of migrant patients injured by falls at the United States-Mexico border. To prevent migrant crossings, a 2017 Executive Order allocated funds to increase the southern California border wall height from 10 ft to 30 ft, which was completed in December 2019. We hypothesized that the elevated border wall height is associated with increased major trauma, resource utilization, and health care costs.

METHODS

Retrospective trauma registry review of border wall falls was performed by the two Level I trauma centers that admit border fall patients from the southern California border from January 2016 to June 2022. Patients were assigned to either "pre-2020" or "post-2020" subgroups based upon timing of completion of the heightened border wall. Total number of admissions, operating room utilization, hospital charges, and hospital costs were compared.

RESULTS

Injuries from border wall falls grew 967% from 2016 to 2021 (39 vs. 377 admissions); this percentage is expected to be supplanted in 2022. When comparing the two subgroups, operating room utilization (175 vs. 734 total operations) and median hospital charges per patient ($95,229 vs. $168,795) have risen dramatically over the same time period. Hospital costs increased 636% in the post-2020 subgroup ($11,351,216 versus $72,172,123). The majority (97%) of these patients are uninsured at admission, with costs largely subsidized by federal government entities (57%) or through state Medicaid enrollment postadmission (31%).

CONCLUSION

The increased height of the United States-Mexico border wall has resulted in record numbers of injured migrant patients, placing novel financial and resource burdens on already stressed trauma systems. To address this public health crisis, legislators and health care providers must conduct collaborative, apolitical discussions regarding the border wall's efficacy as a means of deterrence and its impact on traumatic injury and disability.

LEVEL OF EVIDENCE

Prognostic and Epidemiological; Level IV.

Multi-disciplinary care in patients with complex pediatric general and thoracic surgical pathology: lessons learned from a 20-year experience

PURPOSE

Complex pediatric surgery patients with thoracic tumors invading the mediastinum and infradiaphragmatic tumors extending into the chest are at risk for surgical morbidity and mortality if the patient's care is not coordinated. We sought to identify areas of focus when managing these patients to improve care.

METHODS

A 20-year, retrospective study of pediatric patients with complex surgical pathology was performed. Demographic data, pre-operative characteristics, intraoperative data, complications, and outcomes data were collected. Three index cases were highlighted to provide granularity in patient management.

RESULTS

Twenty-six patients were identified. Common pathology included mediastinal teratomas, foregut duplications, advanced Wilms tumors, hepatoblastoma, and lung masses. All cases were performed in a multidisciplinary fashion. All cases were done with pediatric cardiothoracic surgery and three cases (11.5%) required pediatric otolaryngology. Eight patients (30.7%) required cardiopulmonary bypass. Operative and 30-day mortality was zero.

CONCLUSIONS

Management of complex pediatric surgical patients requires a multidisciplinary approach throughout the patient's hospital course. This multidisciplinary team should meet in advance of a patient's procedure to create a customized care plan that may include pre-operative optimization. At the time of their procedure, all necessary and emergency equipment should available. This approach improves patient safety and has resulted in excellent outcomes.

LEVEL OF EVIDENCE

IV.

Modified laparoscopic gastrostomy tube placement in children: Does subcutaneous suture type matter?

BACKGROUND

Laparoscopic gastrostomy tube (GT) placement carries the risk of early tube dislodgement and is often modified with absorbable subcutaneously-tunneled transabdominal tacking sutures that can aid in tube replacement. However, these buried sutures may increase the risk of surgical site infection (SSI). This study sought to evaluate SSI rates associated with different types of transabdominal tacking sutures used in modified laparoscopic GT placement.

METHODS

A single-institution, retrospective review was performed of all patients ≤18 years-old undergoing modified laparoscopic GT placement between September 2016 and March 2020. Patients were stratified into three groups by suture type used, and the primary outcome was SSI within six weeks of surgery. Demographic and perioperative data were analyzed by chi-square or Fisher's exact test.

RESULTS

A total of 113 modified laparoscopic GT placements were performed at a median age of 9 months (interquartile range 3 months to 3 years). Prophylactic antibiotic use was similar between groups. Eleven patients (10%) developed an SSI, and all were treated with antibiotics alone. No SSIs were observed with the use of poliglecaprone suture (n = 46), and higher SSI rates were observed with use of polyglactin (n = 17) and polydioxanone (n = 51) suture (18% polyglactin vs. 16% polydioxanone vs. 0% poliglecaprone, p<0.05). No differences were observed in rates of early postoperative dislodgement, leakage, or granulation tissue.

CONCLUSION

Absorbable braided and long-lasting monofilament transabdominal tacking sutures may increase risk of SSI following modified laparoscopic gastrostomy tube placement. In this cohort, the use of poliglecaprone (Monocryl) suture was associated with no SSIs and similar rates of postoperative dislodgement, leakage, and granulation tissue.

LEVEL OF EVIDENCE

Treatment Study, Level III.

Minimizing the risk of occupational Q fever exposure: A protocol for ensuring Coxiella burnetii-negative pregnant ewes are used for medical research

Q fever is a worldwide zoonosis caused by Coxiella burnetii that can lead to abortion, endocarditis, and death in humans. Researchers utilizing parturient domestic ruminants, including sheep, have an increased risk of occupational exposure. This study evaluated the effectiveness of our screening protocol in eliminating C. burnetii-positive sheep from our facility. From August 2010 to May 2018, all ewes (N  =  306) and select lambs (N  =  272; ovis aries) were screened twice for C. burnetii utilizing a serum Phase I and Phase II antibody immunofluorescence assay (IFA). The first screen was performed by the vendor prior to breeding, and the second screen was performed on arrival to the research facility. Ewes that were positive on arrival screening were quarantined and retested using repeat IFA serology, enzyme-linked immunosorbent assay, buffy coat polymerase chain reaction (PCR), and amniotic fluid PCR. The overall individual seroprevalence of C. burnetii in the flocks tested by the vendor was 14.2%. Ewes with negative Phase I and Phase II IFA results were selected for transport to the research facility. Upon arrival to the facility, two (0.7%) ewes had positive Phase I IFA results. Repeat testing demonstrated seropositivity in one of these two ewes, though amniotic fluid PCR was negative in both. The repeat seropositive ewe was euthanized prior to use in a research protocol. No Q fever was reported among husbandry, laboratory or veterinary staff during the study period. Serologic testing for C. burnetii with IFA prior to transport and following arrival to a research facility limits potential exposure to research staff.

A Decade of Experience with the Ovine Model of Myelomeningocele: Risk Factors for Fetal Loss

INTRODUCTION

The ovine model is the gold standard large animal model of myelomeningocele (MMC); however, it has a high rate of fetal loss. We reviewed our experience with the model to determine risk factors for fetal loss.

METHODS

We performed a retrospective review from 2009 to 2018 to identify operative factors associated with fetal loss (early fetal demise, abortion, or stillbirth). Operative risk factors included gestational age at operation, operative time, reduction of multiple gestations, amount of replaced amniotic fluid, ambient temperature, and method of delivery.

RESULTS

MMC defects were created in 232 lambs with an overall survival rate of 43%. Of the 128 fetuses that died, 53 (42%) had demise prior to repair, 61 (48%) aborted, and 14 (11%) were stillborn. Selective reduction of multiple gestations in the same uterine horn was associated with increased fetal demise (OR 3.03 [95% CI 1.29-7.05], p = 0.01). Later gestational age at MMC repair and Cesarean delivery were associated with decreased abortion/stillbirth (OR 0.90 [95% CI 0.83-0.90], p = 0.03, and OR 0.37 [95% CI 0.16-0.31], p = 0.02), respectively.

CONCLUSION

Avoiding selective reduction, repairing MMC later in gestation, and performing Cesarean delivery decreases the rate of fetal loss in the ovine MMC model.

Neuroprotective effect of placenta-derived mesenchymal stromal cells: role of exosomes

We have established early-gestation chorionic villus-derived placenta mesenchymal stromal cells (PMSCs) as a potential treatment for spina bifida (SB), a neural tube defect. Our preclinical studies demonstrated that PMSCs have the potential to cure hind limb paralysis in the fetal lamb model of SB via a paracrine mechanism. PMSCs exhibit neuroprotective function by increasing cell number and neurites, as shown by indirect coculture and direct addition of PMSC-conditioned medium to the staurosporine-induced apoptotic human neuroblastoma cell line, SH-SY5Y. PMSC-conditioned medium suppressed caspase activity in apoptotic SH-SY5Y cells, suggesting that PMSC secretome contributes to neuronal survival after injury. As a part of PMSC secretome, PMSC exosomes were isolated and extensively characterized; their addition to apoptotic SH-SY5Y cells mediated an increase in neurites, suggesting that they exhibit neuroprotective function. Proteomic and RNA sequencing analysis revealed that PMSC exosomes contain several proteins and RNAs involved in neuronal survival and development. Galectin 1 was highly expressed on the surface of PMSCs and PMSC exosomes. Preincubation of exosomes with anti-galectin 1 antibody decreased their neuroprotective effect, suggesting that PMSC exosomes likely impart their effect via binding of galectin 1 to cells. Future studies will include in-depth analyses of the role of PMSC exosomes on neuroprotection and their clinical applications.-Kumar, P., Becker, J. C., Gao, K., Carney, R. P., Lankford, L., Keller, B. A., Herout, K., Lam, K. S., Farmer, D. L., Wang, A. Neuroprotective effect of placenta-derived mesenchymal stromal cells: role of exosomes.

Subcutaneous local anesthetic infusion could eliminate use of epidural analgesia after the Nuss procedure

AIM

To compare outcomes of continuous subcutaneous infusion of local anesthetic and epidural analgesia following the Nuss procedure.

PATIENTS & METHODS

A retrospective chart review compared patients managed with subcutaneous local anesthetic infusion (n = 12) versus thoracic epidural (n = 19) following the Nuss procedure from March 2013 to June 2015.

RESULTS

There was no difference in hospital length of stay or days on intravenous narcotics. Epidural catheter placement prolonged operating room time (146.58 ± 28.30 vs 121.42 ± 21.98 min, p = 0.01). Average pain scores were slightly higher in the subcutaneous infusion group (3.72 ± 1.62 vs 2.35 ± 0.95, p = 0.02), but of negligible clinical significance.

CONCLUSION

Continuous subcutaneous infusion of local anesthetic could eliminate the need for thoracic epidural for pain management after the Nuss procedure.

Intercostal nerve cryoablation versus thoracic epidural catheters for postoperative analgesia following pectus excavatum repair: Preliminary outcomes in twenty-six cryoablation patients

BACKGROUND

Multimodal pain management strategies are used for analgesia following pectus excavatum repair. However, the optimal regimen has not been identified. We describe our early experience with intercostal cryoablation for pain management in children undergoing the Nuss procedure and compare early cryoablation outcomes to our prior outcomes using thoracic epidural analgesia.

METHODS

A multi-institutional, retrospective review of fifty-two patients undergoing Nuss bar placement with either intercostal cryoablation (n=26) or thoracic epidural analgesia (n=26) from March 2013 to January 2016 was conducted. The primary outcome was hospital length of stay. Secondary outcomes included telemetry unit monitoring time, total intravenous narcotic use, duration of intravenous narcotic use, and postoperative complications.

RESULTS

Patients who underwent intercostal cryoablation had a significant reduction in the mean hospital length of stay, time in a monitored telemetry bed, total use of intravenous narcotics, and the duration of intravenous narcotic administration when compared to thoracic epidural patients. Cryoablation patients had a slightly higher rate of postoperative complications.

CONCLUSION

Intercostal cryoablation is a promising technique for postoperative pain management in children undergoing repair of pectus excavatum. This therapy results in reduced time to hospital discharge, decreased intravenous narcotic utilization, and has eliminated epidurals from our practice.

LEVEL OF EVIDENCE

Retrospective study - level III.

Fetal surgery for myelomeningocele: history, research, clinical trials, and future directions

Myelomeningocele, more commonly known as spina bifida, is the most common neural tube defect worldwide. In the United States, it is the primary cause of lifelong childhood paralysis with approximately four children born daily with this devastating disease. To minimize damage to the exposed spinal cord and prevent ascending central nervous system infections, postnatal closure of the spinal defect has been the standard of care for decades. Research into the mechanism of spinal cord injury in those with spina bifida revealed that damage continues to accrue during the gestational period. Prenatal defect closure via in utero surgery was proposed to prevent this early deterioration of the spinal cord, and early animal research demonstrated that prenatal repair was feasible and promising. This paved the way for the first human prenatal repairs in the mid-to-late 1990s. Following the promising outcomes observed during the first human cases, a randomized controlled trial, the Management of Myelomeningocele Study (MOMS), was conducted comparing postnatal repair of spina bifida to prenatal repair. The MOMS trial demonstrated that to those undergoing prenatal repair of spina bifida had a decreased need for ventriculoperitoneal shunting and improved lower extremity motor function. With the success of the MOMS trial, in utero repair is now considered the standard of care in those who meet the criteria for prenatal repair. This review will provide an overview of spina bifida and its impact, highlight the historical changes in care, describe the early research and theory that made prenatal repair an option, discuss the clinical experiences with human fetal repair and briefly touch on future research directions for those with myelomeningocele.

Age Does Matter: A Pilot Comparison of Placenta-Derived Stromal Cells for in utero Repair of Myelomeningocele Using a Lamb Model

INTRODUCTION

Fetal amniotic membranes (FM) have been shown to preserve spinal cord histology in the fetal sheep model of myelomeningocele (MMC). This study compares the effectiveness of placenta-derived mesenchymal stromal cells (PMSCs) from early-gestation versus term-gestation placenta to augment FM repair to improve distal motor function in a sheep model.

METHODS

Fetal lambs (n = 4) underwent surgical MMC creation followed by repair with FM patch with term-gestation PMSCs (n = 1), FM with early-gestation PMSCs (n = 1), FM only (n = 1), and skin closure only (n = 1). Histopathology and motor assessment was performed.

RESULTS

Histopathologic analysis demonstrated increased preservation of spinal cord architecture and large neurons in the lamb repaired with early-gestation cells compared to all others. Lambs repaired with skin closure only, FM alone, and term-gestation PMSCs exhibited extremely limited distal motor function; the lamb repaired with early-gestation PMSCs was capable of normal ambulation.

DISCUSSION

This pilot study is the first in vivo comparison of different gestational-age placenta-derived stromal cells for repair in the fetal sheep MMC model. The preservation of large neurons and markedly improved motor function in the lamb repaired with early-gestation cells suggest that early-gestation placental stromal cells may exhibit unique properties that augment in utero MMC repair to improve paralysis.

Innate healing in the fetal sheep model of myelomeningocele: A standardized defect grading system

BACKGROUND/PURPOSE

The fetal sheep model of myelomeningocele (MMC) is well-established. While the variability of innate fetal healing of the defect at the time of the repair operation has been acknowledged, it remains poorly described. We characterized the healing within the fetal sheep MMC model and present a standardized defect grading system.

METHODS

Forty-three fetuses underwent surgical MMC creation at a gestational age of 75 days and repair at 100 days. Defects were graded based on percentage of exposed spinal cord and degree of scarring. A scale was developed and validated by interrater reliability testing.

RESULTS

The phenotypic appearance of the defect at the time of the repair operation was highly variable. The defect length ranged from 3.0 to 5.5cm. Three spinal cords remained fully exposed across their length; 18 were completely covered in fibrinous exudate. Twenty-two fetuses demonstrated varying degrees of open spinal cord. Interrater reliability revealed consistent grades 91% of the time.

CONCLUSION

Despite consistent defect creation, the fetal MMC defect has a wide spectrum of appearance at the time of the second surgery. This study describes the innate fetal healing within the model and presents a feasible and valid grading scale to ensure scientific rigor within the model.

Placental mesenchymal stromal cells rescue ambulation in ovine myelomeningocele

Myelomeningocele (MMC)-commonly known as spina bifida-is a congenital birth defect that causes lifelong paralysis, incontinence, musculoskeletal deformities, and severe cognitive disabilities. The recent landmark Management of Myelomeningocele Study (MOMS) demonstrated for the first time in humans that in utero surgical repair of the MMC defect improves lower limb motor function, suggesting a capacity for improved neurologic outcomes in this disorder. However, functional recovery was incomplete, and 58% of the treated children were unable to walk independently at 30 months of age. In the present study, we demonstrate that using early gestation human placenta-derived mesenchymal stromal cells (PMSCs) to augment in utero repair of MMC results in significant and consistent improvement in neurologic function at birth in the rigorous fetal ovine model of MMC. In vitro, human PMSCs express characteristic MSC markers and trilineage differentiation potential. Protein array assays and enzyme-linked immunosorbent assay show that PMSCs secrete a variety of immunomodulatory and angiogenic cytokines. Compared with adult bone marrow MSCs, PMSCs secrete significantly higher levels of brain-derived neurotrophic factor and hepatocyte growth factor, both of which have known neuroprotective capabilities. In vivo, functional and histopathologic analysis demonstrated that human PMSCs mediate a significant, clinically relevant improvement in motor function in MMC lambs and increase the preservation of large neurons within the spinal cord. These preclinical results in the well-established fetal ovine model of MMC provide promising early support for translating in utero stem cell therapy for MMC into clinical application for patients.

SIGNIFICANCE

This study presents placenta-derived mesenchymal stromal cell (PMSC) treatment as a potential therapy for myelomeningocele (MMC). Application of PMSCs can augment current in utero surgical repair in the well-established and rigorously applied fetal lamb model of MMC. Treatment with human PMSCs significantly and dramatically improved neurologic function and preserved spinal cord neuron density in experimental animals. Sixty-seven percent of the PMSC-treated lambs were able to ambulate independently, with two exhibiting no motor deficits whatsoever. In contrast, none of the lambs treated with the vehicle alone were capable of ambulation. The locomotor rescue demonstrated in PMSC-treated lambs indicates great promise for future clinical trials to improve paralysis in children afflicted with MMC.

Development of a locomotor rating scale for testing motor function in sheep

BACKGROUND/PURPOSE

Research to cure paralysis associated with myelomeningocele (MMC) is ongoing using the fetal sheep model of MMC. Despite decades of research using this model, no standardized motor function assessment exists. The purpose of this study is to develop a sensitive and reliable locomotor scale for assessing the functional status of sheep.

METHODS

Twenty lambs were used to develop and validate the locomotor scale. Lambs (n=15) underwent a surgically created MMC defect at gestational age (GA) 75 days, followed by repair with various methods at GA 100. One lamb underwent a sham operation (n=1). Normal lambs (n=4) served as controls. All lambs were born via spontaneous vaginal delivery, and motor function was assessed for 24 hours. A locomotor rating scale was developed based on behavioral observations of lambs. Inter-rater reliability testing was performed to determine if the scale could be reliably applied by different raters.

RESULTS

Observations led to the definition of 7 categories of locomotor recovery. A scoring system was developed to rank these categories. The scale captured a wide variety of neurologic outcomes. Inter-rater reliability revealed minimal variability between examiners (average standard deviation ±0.431). The average score for all raters was within 1 point of the consensus score 100% of the time.

CONCLUSIONS

The sheep locomotor rating scale is capable of capturing subtle differences in neurologic function with minimal inter-rater variability. We propose a standardized rating scale for neurologic outcomes and believe this is a critical component for assessing the validity of experimental treatments to cure paralysis in MMC.

Effects of meal form and composition on plasma testosterone, cortisol, and insulin following resistance exercise

The purpose of this study was to examine the effects of postexercise feeding on plasma levels of insulin, testosterone, cortisol, and testosterone:cortisol (T:C). Ten experienced, resistance trained males (20.7 +/- 0.95 years) were given whole food (WF: protein 38 g; carbohydrate 70 g; fat 7 g), a supplemental drink (SD; isocaloric and isonitrogenous to WF), an isocaloric carbohydrate beverage (C), or a placebo beverage (P) immediately, 2 and 4 hours after a standardized weight training protocol on 4 days, each separated by 1 week, in a repeated measures design. Subjects also received a standardized meal at 7 and 12 hours postexercise. Insulin, testosterone, and cortisol were measured pre-exercise and during 24 hours of recovery (at 0.5, 2.5, 4.5, 8, and 24 hours) using venous blood samples. Significant (condition 3 time) interactions were found for insulin, testosterone, and T:C, but not for cortisol (p <. 05). The SD yielded a greater response for insulin than all other conditions. Conversely, P demonstrated the greatest values for testosterone and T:C at 2.5 and 4.5 hours postexercise. Cortisol did not vary between conditions and there were no condition effects for insulin, testosterone, cortisol, and T:C at 8 or 24 hours. In conclusion, the efficacy of postexercise feeding for optimizing T:C and muscle growth is unclear; however, consumption of SD appears to maximize circulating insulin for several hours following resistance exercise.

Mutations at arg486 and glu571 in human topoisomerase IIalpha confer resistance to amsacrine: relevance for antitumor drug resistance in human cells

Human topoisomerase II, a nuclear protein involved in chromosome segregation, is the target of amsacrine and other clinically important anticancer drugs. The enzyme is expressed as alpha and beta isoforms whose mutation/down-regulation has been implicated in drug resistance. To understand the role of target mutations in cellular drug resistance, we have used yeast to select and characterize plasmid-borne human topoisomerase IIalpha mutants resistant to amsacrine. Single point changes of Glu571 to Lys (E571K) or Arg486 to Lys (R486K) in the conserved PLRGK motif, both of which reside in the GyrB homology domain of human topoisomerase IIalpha, were frequently selected and could be shown in vivo to confer >25-fold and >100-fold resistance, respectively, to amsacrine and approximately 3-fold cross-resistance to etoposide. Highly purified E571K and R486K human topoisomerase IIalpha proteins required 100-fold higher levels of amsacrine to induce DNA cleavage similar to that of wild-type protein, consistent with a resistance mechanism involving reduced cleavable complex formation. Our functional studies of the R486K mutation, previously identified in two amsacrine-resistant human cell lines and in human biopsy material, establish unequivocally that it confers resistance, and suggest mechanisms for its phenotypic expression in vivo. These results differ significantly from previous work using yeast topoisomerase II as a model system: introduction of the equivalent mutation to R486K (R476K) into the yeast enzyme did not give amsacrine resistance. We conclude that species-specific differences in topoisomerase II enzymes can affect the drug resistance phenotype of particular mutations and highlight the need to study the relevant human homolog.

Noninvasive estimation of the maximal lactate steady state in trained cyclists

PURPOSE

The purposes of this study were to estimate noninvasively the maximal lactate steady state (MLSS) in trained cyclists on a windload simulator with a velocity based technique and to determine whether the HR at MLSS (HR(MLSS)) elicited a similar blood lactate concentration (BLC) during field testing.

METHODS

To determine and verify MLSS, 10 male cyclists performed five to seven laboratory trials on separate days, including a VO2max test; a 5-km time trial (TT); and two or more 30-min trials at specific percentages of each subject's average 5-km TT speed (AVS5km). Mean+/-SD for the following variables were obtained at MLSS: velocity was 90.3+/-2.7% of the AVS5km, BLC was 5.4+/-1.6 mM, RPE was 15+/-2.1, VO2 was 80+/-6.3% of VO2max, and HR was 167+/-9.5 beats x min(-1), which was 88+/-3.8% of the mean maximum HR. Field tests included three laps of an 8-km road circuit at HR(MLSS) +/-3 beats x min(-1) and one lap at maximum sustainable velocity (a road TT).

RESULTS

There were no significant differences in BLC, HR, and RPE between the three steady-state road laps and the lab MLSS trial. There was also good agreement between the road and lab MLSS velocity/TT velocity ratios.

CONCLUSIONS

Our data suggest that 5-km TT cycling velocity, as measured on a windload simulator, may be used to estimate MLSS and the HR at MLSS for training purposes.

Impact of rapid weight loss on cognitive function in collegiate wrestlers

PURPOSE

The purpose of this study was to examine the effects of rapid weight loss (RWL) on cognitive function in collegiate wrestlers.

METHODS

Wrestlers (N = 14) and controls (N = 15) were college-aged males who were tested at three different times: baseline, RWL, and rehydration. Wrestlers practiced RWL in preparation for competition while controls maintained normal body weight and dietary practices throughout the study. At each test session, blood glucose, hemoglobin (Hgb), hematocrit (Hct), plasma volume (PV), and body weight were measured. Subjects also completed mood and hypoglycemic profiles as well as five short cognitive tests.

RESULTS

Two-way ANOVA and post-hoc tests revealed poorer performance for wrestlers than controls in two recall tests as well as greater mood negativity for the wrestlers after RWL. With RWL, between group differences were also evident in hypoglycemic profile, blood glucose, PV, and body weight. All measures returned to near baseline values after rehydration, suggesting that all physiological and cognitive effects associated with RWL were reversible. It is possible that precompetition anxiety may partially explain the results.

CONCLUSIONS

RWL in collegiate wrestlers before a competition appears to cause physiological effects that are accompanied by transient mood reduction and impairment of short-term memory. The potential negative impact of this practice on the student-athlete should be considered.

Identification of yeast DNA topoisomerase II mutants resistant to the antitumor drug doxorubicin: implications for the mechanisms of doxorubicin action and cytotoxicity

Doxorubicin is a therapeutically useful anticancer drug that exerts multiple biological effects. Its antitumor and cardiotoxic properties have been ascribed to anthracycline-mediated free radical damage to DNA and membranes. Evidence for this idea comes in part from the selection by doxorubicin from stationary phase yeast cells of mutants (petites) deficient in mitochondrial respiration and therefore defective in free radical generation. However, doxorubicin also binds to DNA topoisomerase II, converting the enzyme into a DNA damaging agent through the trapping of a covalent enzyme-DNA complex termed the 'cleavable complex.' We have used yeast to determine whether stabilization of cleavable complexes plays a role in doxorubicin action and cytotoxicity. A plasmid-borne yeast TOP2 gene was mutagenized with hydroxylamine and used to transform drug-permeable yeast strain JN394t2-4, which carries a temperature-sensitive top2-4 mutation in its chromosomal TOP2 gene. Selection in growth medium at the nonpermissive temperature of 35 degrees in the presence of doxorubicin resulted in the isolation of plasmid-borne top2 mutants specifying functional doxorubicin-resistant DNA topoisomerase II. Single-point changes of Gly748 to Glu or Ala642 to Ser in yeast topoisomerase II, which lie in and adjacent to the CAP-like DNA binding domain, respectively, were identified as responsible for resistance to doxorubicin, implicating these regions in drug action. None of the mutants selected in JN394t2-4, which has a rad52 defect in double-strand DNA break repair, was respiration-deficient. We conclude that topoisomerase II is an intracellular target for doxorubicin and that the genetic background and/or cell proliferation status can determine the relative importance of topoisomerase II- versus free radical-killing.

Water running with and without a flotation vest in competitive and recreational runners

The purpose of this study was to determine whether competitive and recreational runners would replicate land training intensity during water immersion (WI) running with (V) and without (NV) a flotation vest and during treadmill running (Tm). Seven female competitive runners (CR) and seven female noncompetitive runners (NR) were asked to replicate preferred land training intensity characteristic of a 45-min run under three conditions (Tm, V, and NV). When 20-min submaximal runs at the preferred land training intensity were performed for Tm, V, and NV conditions, CR were able to elicit a similar submaximal VO2 for all three conditions. In contrast, the NR group had a significantly (P < 0.05) lower VO2 (27%), HR (23%), VE (26%) and %VO2max (27%) during V versus Tm condition. During the NV condition, NR had a significantly lower VO2 (13%), %VO2max (13%), and a higher RPE compared with Tm running, and a significantly higher VO2 (16%), HR (15%), VE (24%), %VO2max (15%) and RPE compared with the V condition. Competitive runners were able to achieve training intensities similar to land training for WI running with or without a flotation vest. However, recreational runners failed to replicate land training pace, where intensity was significantly lower during WI running without a vest and lowest with a vest, despite efforts to maintain a similar level of exertion.

Molecular cloning and expression of the Candida albicans TOP2 gene allows study of fungal DNA topoisomerase II inhibitors in yeast

Candida albicans topoisomerase II, encoded by the TOP2 gene, mediates chromosome segregation by a double-strand DNA break mechanism and is a potential target for anti-fungal therapy. In this paper, we report the characterization of the C. albicans TOP2 gene and its use to develop a yeast system that allows the identification and study of anti-fungal topoisomerase II inhibitors in vivo. The gene, specifying a 1461-residue polypeptide with only 40% identity with human topoisomerase IIalpha and beta isoforms, was isolated from C. albicans on a 6.3 kb EcoRI fragment that mapped to chromosome 4. It was used to construct a plasmid in which TOP2 expresses a recombinant enzyme (residues 57-1461 of C. albicans topoisomerase II fused to the first five residues of Saccharomyces cerevisiae topoisomerase II) under the control of a galactose-inducible promoter. The plasmid rescued the lethal phenotype of a temperature-sensitive S. cerevisiae DNA topoisomerase II mutant allowing growth at 35 degrees C. Yeast cells, bearing ISE2 permeability and rad52 double-strand-break-repair mutations the growth of which at 35 degrees C was dependent on C. albicans topoisomerase II, were killed by the known topoisomerase II inhibitors amsacrine and doxorubicin. Parallel experiments in yeast expressing human topoisomerase IIalpha allowed the relative sensitivities of the fungal and host topoisomerases to be examined in the same genetic background. To compare the killing in vivo with drug inhibition in vitro, the recombinant C. albicans topoisomerase II protein was expressed and purified to near-homogeneity from S. cerevisiae yielding a 160 kDa polypeptide that displayed the expected ATP-dependent DNA-relaxation and DNA-decatenation activities. The enzyme, whether examined in vitro or complementing in S. cerevisiae, was comparably sensitive to amsacrine and doxorubicin. Our results suggest that potential topoisomerase II-targeting anti-fungal inhibitors can be identified and studied in S. cerevisiae.

Modification in movement accuracy in the triphasic pattern during a rapid forearm-flexion task

The present study was designed to investigate modifications in the triphasic EMG pattern during a forearm-flexion task at maximum speed which required three levels of movement accuracy. 36 subjects participated in 4 training sessions, performing a total of 200 repetitions of each movement. The fastest movement time was associated with the least accurate movement task. Likewise, the slowest movement time was found for the movement requiring the greatest accuracy. Differences in the duration and amplitude of agonist 1 activity, the start of agonist 2 activity, and the start and amplitude of antagonist activity were observed for the three movements. The results indicate that agonist 1 provides a propulsive force to initiate limb movement. The antagonist EMG activity was thought responsible for braking and correcting limb movement. Modifications in agonist 2 activity suggest this burst is related to movement velocity.