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Biomedical subjects

B R Brown

Publications and source records attributed to B R Brown.

At least 19 recordsLinked to original sources
PubMed2001

Fast pitch softball injuries.

The popularity of fast pitch softball in the US and throughout the world is well documented. Along with this popularity, there has been a concomitant increase in the number of injuries. Nearly 52% of cases qualify as major disabling injuries requiring 3 weeks or more of treatment and 2% require surgery. Interestingly, 75% of injuries occur during away games and approximately 31% of traumas occur during nonpositional and conditioning drills. Injuries range from contusions and tendinitis to ligamentous disorders and fractures. Although head and neck traumas account for 4 to 12% of cases, upper extremity traumas account for 23 to 47% of all injuries and up to 19% of cases involve the knee. Approximately 34 to 42% of injuries occur when the athlete collides with another individual or object. Other factors involved include the quality of playing surface, athlete's age and experience level, and the excessive physical demands associated with the sport. Nearly 24% of injuries involve base running and are due to poor judgement, sliding technique, current stationary base design, unorthodox joint and extremity position during ground impact and catching of cleats. The increasing prevalence of overtraining syndrome among athletes has been attributed to an unclear definition of an optimal training zone, poor communication between player and coach, and the limited ability of bone and connective tissue to quickly respond to match the demands of the sport. This has led routinely to arm, shoulder and lumbar instability, chronic nonsteroidal anti-inflammatory drug (NSAID) use and time loss injuries in 45% of pitching staff during a single season. Specific attention to a safer playing environment, coaching and player education, and sport-specific training and conditioning would reduce the risk, rate and severity of fast pitch traumas. Padding of walls, backstops, rails and dugout areas, as well as minimising use of indoor facilities, is suggested to decrease the number of collision injuries. Coaches should be cognisant of overtraining, vary day-to-day training routines to decrease repetitive musculoskeletal stress, focus on motor skills with equal emphasis on speed and efficiency of movement, and use drills that reinforce sport-specific, decision making processes to minimise mental mistakes. Conditioning programs that emphasise a combination of power, acceleration, flexibility, technical skill, functional capacity and injury prevention are recommended. Due to the limited body of knowledge presently available on this sport, a greater focus on injury surveillance would provide a clearer picture of injury causation and effective management procedures, leading toward safer participation and successful player development.

Adolescent↗
PubMed1999

Fiberoptic bronchoscopic placement of self-expandable metallic airway stents for the treatment of tracheobronchial obstruction and fistulas.

Tracheobronchial stent use has been reported in the medical literature for more than 40 years. Silicone stents are the most widely used stents in therapy for varying tracheobronchial lesions at most centers. However, newer designs and modifications of stents are now available with delivery systems that have been designed to facilitate using fiberoptic bronchoscopy. We describe our initial experience placing 13 self-expandable metallic Wallstent stents, including the covered design, in a total of seven patients via a fiberoptic bronchoscope. All patients had benign or malignant obstructing lesions and one patient had an associated malignant tracheoesophageal fistula. The procedure was technically easy and was well tolerated. Following stenting there was a visible increase in airway diameter and a marked improvement in symptoms for all patients. Median survival after stent placement is currently 10 months.

Adult↗
PubMed1997

Improved results in the management of surgical candidates with lung cancer.

BACKGROUND: Perioperative mortality and morbidity after lung resection for carcinoma are generally reported to be 3% to 6% and 15% to 30%, respectively, and higher in the elderly and those with limited cardiopulmonary reserve. METHODS: To minimize this risk and extend the surgical option to more high-risk patients, we adopted a protocol in 1991 that included preoperative digitalis, subcutaneous heparin and venoocclusive stockings, aggressive perioperative pulmonary toilet, and video-directed limited resections for many patients with limited pulmonary reserve. In October 1996, we reviewed our results with 173 consecutive patients (median age, 60 years; range, 17 to 89 years) undergoing operation for suspected lung carcinoma. Forty-one patients were 70 years old or older, and 70 patients were considered high risk on the basis of advanced age (> or = 70 years), poor cardiac or pulmonary reserve, or serious medical comorbidity. Procedures included pneumonectomy (n = 31), lobectomy (n = 83), bilobectomy (n = 12), and limited resection (n = 45). Two patients had unresectable disease. RESULTS: Hospital mortality was 1.6% (3/173) and morbidity was experienced by 15% (26/173). Among the high-risk subgroup mortality was 4.2% (3/70) and morbidity was 20% (14/70; p < 0.03). For the older patients these values were 4.8% (2/41) and 17.9% (7/41), respectively. CONCLUSIONS: Morbidity and mortality from lung resections may be minimized with the perioperative management strategy outlined above. This would allow more high-risk patients to benefit from surgical resection, and do so with an acceptably low risk.

Adenocarcinoma↗
PubMed1996

Compound A concentrations during sevoflurane anesthesia in children.

BACKGROUND: Sevoflurane is a new inhalation agent that should be useful for pediatric anesthesia. Sevoflurane undergoes degradation in the presence of carbon dioxide absorbents; however, quantification of the major degradation product (compound A) has not been evaluated during pediatric anesthesia. This study evaluates sevoflurane degradation compound concentrations during sevoflurane anesthesia using a 2-1 fresh gas flow and a circle system with carbon dioxide absorber in children with normal renal and hepatic function. METHODS: The concentrations of compound A were evaluated during sevoflurane anesthesia in children using fresh soda lime as the carbon dioxide absorbent. Nineteen patients aged 3 months-7 yr were anesthetized with sevoflurane (2.8% mean end-tidal concentration) using a total fresh gas flow of 21 in a circle absorption system. Inspiratory and expiratory limb circuit gas samples were obtained at hourly intervals, and the samples were analyzed using a gas chromatography-flame ionization detection technique. Carbon dioxide absorbent temperatures were measured in the soda lime during anesthesia for hepatic and renal function studies. Venous blood samples were obtained before anesthesia, at the end of anesthesia, and 2h after anesthesia for plasma inorganic fluoride ion concentration. RESULTS: The maximum inspiratory concentration of compound A was 5.4 +/- 4.4 ppm (mean +/- SD), and the corresponding expiratory concentration was 3.7 +/- 2.7 ppm (mean +/- SD). The maximum inspiratory compound A concentration in any patient was 15 ppm. Mean concentrations of compound A peaked at intubation and remained stable, declining slightly after 120 min of anesthesia. The duration of anesthesia was 240 +/- 139 min (mean +/-SD). Maximum soda lime temperature ranged between 23.1 degrees C and 40.9 degrees C. There was a positive correlation between maximum absorbent temperature and maximum compound A concentration (r2 = 0.58), as well as between the child's body surface area and maximum compound A concentration (r2 = 0.59). Peak plasma inorganic fluoride ion concentration was 21.5 +/- 6.1 microgmol/1. There were no clinically significant changes in hepatic or renal function studies performed 24 h postanesthesia. CONCLUSIONS: Sevoflurane anesthesia of 4 h in normal children using a 2-1 flow circle system produced concentrations of compound A of 15 ppm or less. There was no evidence of abnormality of renal or hepatic function up to 24 h after anesthesia; however, larger studies will be required to confirm the absence of organ toxicity.

Anesthesia↗
PubMed1996

Searching for the Magic Johnson effect: AIDS, adolescents, and celebrity disclosure.

The objectives of this study were to measure changes in AIDS-related attitudes and behaviors in adolescents in the 13 months following Magic Johnson's disclosure that he was HIV positive, and to test whether gender, race, age, sexual experience, and pre-existing HIV-avoidant behaviors would emerge as significant dependent variables. Adolescent clinic attendees (N = 181) ages 12-19 in four cities completed a questionnaire assessing change in AIDS-related attitudes and behaviors since Johnson's announcement. Respondents were divided into low-risk and at-risk groups. Sixty percent of respondents reported that Magic Johnson's announcement had increased their awareness of AIDS, 65.4% reported increased self-efficacy in a sexual situation, 37.2% reported that they had changed their perceived AIDS risk, 37.8% described increased resistance to peer pressure for sexual intercourse. The low-risk group was more likely to report increased self-efficacy and resistance to peer pressure but no change in perceived risk or increased AIDS awareness. Significant relationships were found between gender and increased AIDS awareness, gender and increased resistance to peer pressure to engage in sexual intercourse, race and increased AIDS awareness, and more lifetime sex partners and increased self-efficacy.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Renal concentrating function with prolonged sevoflurane or enflurane anesthesia in volunteers.

BACKGROUND: Sevoflurane, a new inhalational anesthetic, is biotransformed, producing peak plasma inorganic fluoride concentrations that may exceed 50 microM. We evaluated plasma inorganic fluoride concentrations with prolonged (> 9 MAC-h) sevoflurane or enflurane anesthesia in volunteers and compared renal concentrating function with desmopressin testing 1 and 5 days after anesthesia. METHODS: Fourteen healthy male volunteers received either enflurane or sevoflurane (1-1.2 MAC) for more than 9 MAC-h. Each volunteer was administered three tests of renal concentrating function, with intranasal desmopressin and urine collections performed 1 week before anesthesia and 1 and 5 days after anesthesia. Venous blood samples were obtained for plasma fluoride concentrations during and after anesthesia. Creatinine clearance was determined by 24-h urine collections 7 days before and 4 days after anesthesia. Urine samples were obtained before and 1, 2, and 5 days after anesthesia for determination of n-acetyl-beta-glucosaminidase and creatinine concentrations. RESULTS: Prolonged sevoflurane anesthesia (9.5 MAC-h) did not impair renal concentrating function on day 1 or 5 postanesthesia, as determined by desmopressin testing. Maximal urinary osmolality on day 1 postanesthesia was decreased (< 800 mOsm/kg) in two of seven enflurane-anesthetized volunteers; however, mean results did not differ from the those of the sevoflurane group. Mean peak plasma fluoride ion concentrations were 23 +/- 1 microM 6 h postanesthesia for enflurane and 47 +/- 3 microM at the end of anesthesia for sevoflurane (P < 0.01). There were no changes in creatinine clearance or urinary n-acetyl-beta-glucosaminidase concentration in either anesthetic group. DISCUSSION: Prolonged sevoflurane anesthesia did not impair renal concentrating function, as evaluated with desmopressin testing 1 and 5 days postanesthesia in healthy volunteers. Although with prolonged enflurane anesthesia, mean maximal osmolality values on day 1 postanesthesia did not differ from sevoflurane values, there was evidence in two volunteers at this time point of impairment in renal concentrating function, which normalized 5 days postanesthesia. These results occurred despite a higher peak plasma fluoride ion concentration and greater total inorganic fluoride renal exposure with sevoflurane anesthesia.

Acetylglucosaminidase↗
PubMed1994

Understanding mechanical ventilation: indications for and initiation of therapy.

The growing complexity of mechanical ventilators and the proliferation of new ventilator modes may confuse and intimidate clinicians who on occasion must manage a mechanical ventilator. The fundamental indications for and types of mechanical ventilation are reviewed, and guidelines for basic ventilator settings are provided. By understanding and applying these essentials, the clinician can provide effective mechanical ventilation to most patients who require it. A subsequent article published in this journal will review the related topics of patient monitoring during mechanical ventilation, complications of mechanical ventilation, and weaning from mechanical ventilation.

Acute Disease↗
PubMed1994

Understanding mechanical ventilation: patient monitoring, complications, and weaning.

Mechanical ventilation can provide life saving support to critically ill patients with respiratory failure. The implementation of appropriate monitoring techniques and an awareness of potential complications can increase the safety of mechanical ventilation. Several efficacious weaning methods can be utilized and none is clearly superior to the others. The improper use of any weaning technique can result in respiratory muscle fatigue delaying extubation. Determining patient suitability for extubation is an inexact science. The physical examination during a spontaneous breathing trial and the use of the rapid shallow breathing index can assist the clinician in the difficult decision as to the timing of extubation.

Adult↗
PubMed1994

Guidelines for overseas eye surgery expeditions using short-term volunteers. Surgical Eye Expeditions international.

Many developing countries face the overwhelming problem of addressing preventable and curable blindness. United States-based ophthalmologists can make important contributions in this regard by volunteering to teach and deliver eye care overseas. However, there are a number of potential risks and difficulties. Surgical Eye Expeditions (SEE) International has developed a logistical outline and planning checklist designed to minimize or avoid such problems. Critical components include a firm timetable, advanced planning, advance contact with a local ophthalmologist or organization, and a thorough understanding of the importance of adapting to the needs of other cultures. With a little planning, the average philanthropic ophthalmologist can make major contributions to individuals and communities in developing nations.

Developing Countries↗
PubMed1993

Interphenylene 7-oxabicyclo[2.2.1]heptane oxazoles. Highly potent, selective, and long-acting thromboxane A2 receptor antagonists.

A series of interphenylene 7-oxabicyclo[2.2.1]heptane oxazoles (2) were prepared and evaluated for their thromboxane (TxA2) antagonistic activity in vitro and duration of action in vivo. Examination of the carboxyl side chain indicated that the interphenylene ring substitution pattern and, to a lesser extent, chain length were important factors in determining TxA2 antagonistic potency. For the carboxyl side chain, ortho substitution, a single methylene spacer between the interphenylene and oxabicycloheptane rings, and a propionic acid side-chain length were determined to be optimal. With respect to the oxazole side chain a wide range of amide substituents with diverse structures and lipophilicities were compatible with potent antagonistic activity. Finally, an acidic functional group on the alpha-chain and a hydrogen bond acceptor on the 4-position of the oxazole ring were critical for potent activity. From the analogs prepared 42 (BMS-180,291: [(+)-1S-(1 alpha, 2 alpha, 3 alpha, 4 alpha)-2-[[3-[4-[(n- pentylamino)carbonyl]-2-oxazolyl]-7-oxabicyclo[2.2.1]hept-2- yl]methyl]benzenepropanoic acid) was found to be a potent, selective, and orally-active TxA2 antagonist with a long duration of action and has been selected as a candidate for clinical development. In human platelet-rich plasma, 42 inhibited arachidonic acid (800 microM) and U-46,-619 (10 microM) induced aggregation with I50 values of 7 and 21 nM, respectively. Radioligand binding studies of 42 with [3H]-SQ 29,548 showed a Kd value of 4.0 +/- 1.0 nM in human platelet membranes. Both in vitro and in vivo studies indicated 42 was devoid of direct agonistic activity. In vivo 42 (0.2 mg/kg, po) showed extended protection (T50 = 14.4 h) from U-46,619 (2 mg/kg, iv) induced death in mice, and a single oral dose of 42 (3 mg/kg) abolished U46,619-induced platelet aggregation ex vivo in African green monkeys for > 24 h.

Animals↗
PubMed1993

Renal function after sevoflurane or enflurane anesthesia in the Fischer 344 rat.

Sevoflurane is metabolized to inorganic fluoride, a potential nephrotoxin. To evaluate the nephrotoxic potential of sevoflurane, 1-yr-old male Fischer 344 rats were anesthetized with 10 minimal alveolar anesthetic concentration (MAC) h sevoflurane or enflurane with or without pretreatment with biotransformation-enhancing agents. Peak serum fluoride levels reached 35 microM with sevoflurane anesthesia after pretreatment with phenobarbital and 40 microM after enflurane anesthesia after pretreatment with isoniazid. One day after anesthesia, sevoflurane-anesthetized rats concentrated urine normally in response to subcutaneous administration of 1-deamino-8-D-arginine vasopressin and exhibited no increase in urinary excretion of N-acetyl beta-glucosaminidase. Isoniazid-treated, enflurane anesthetized rats developed a 31% reduction in maximal urinary concentrating ability and a 3.5-fold increase in excretion of N-acetyl-beta-glucosaminidase. Sevoflurane produced no evidence of fluoride-induced nephrotoxicity in noninduced or enzyme-induced rats. Under similar conditions, enflurane produced laboratory evidence of nephrotoxicity.

Anesthesia, Inhalation↗
PubMed1993

Plasma inorganic fluoride levels with sevoflurane anesthesia in morbidly obese and nonobese patients.

Administration of several of the inhaled anesthetics result in plasma inorganic fluoride concentrations that are higher in obese compared to nonobese patients. Sevoflurane, a new inhaled anesthetic, is metabolized to inorganic fluoride; however, plasma inorganic fluoride levels with sevoflurane anesthesia in obese subjects have not been evaluated. We studied plasma inorganic fluoride concentrations during and after sevoflurane surgical anesthesia in morbidly obese (n = 13, body mass index > 35) and nonobese (n = 10) patients. Sevoflurane anesthesia in 60% nitrous oxide/40% oxygen was administered with a semiclosed circle absorption system. Mean anesthetic duration was 1.4 minimum alveolar anesthetic concentration (MAC) hours (sevoflurane MAC = 2.05%) for both groups. Pre- and postoperative blood urea nitrogen, creatinine, and liver function tests were evaluated. Venous blood samples were obtained during and after anesthesia for plasma inorganic fluoride analysis. In six morbidly obese and nonobese patients arterial blood samples were obtained during and after sevoflurane anesthesia for determining sevoflurane blood concentration. Plasma fluoride concentrations during and after anesthesia did not differ between morbidly obese and non-obese groups. Peak plasma inorganic fluoride ion concentrations were 30 +/- 2 mumol/L (mean +/- SEM) in obese and 28 +/- 2 mumol/L in nonobese patients 1 h after discontinuing anesthesia. The hourly rate of change of fluoride ion concentration in plasma during anesthesia was similar between the groups. The maximal recorded plasma fluoride concentrations were 49 mumol/L in an obese patient and 42 mumol/L in a nonobese patient. Pre- and postoperative hepatic and renal tests did not differ significantly in either group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Pulmonary epithelial cell urokinase-type plasminogen activator. Induction by interleukin-1 beta and tumor necrosis factor-alpha.

Diffuse alveolar damage, presenting clinically as adult respiratory distress syndrome, is characterized initially by widespread intra-alveolar fibrin deposition. Alveolar epithelial cells play a central role in the subsequent repair process. We have recently shown that alveolar epithelial cells have the capacity to promote fibrinolysis (Marshall, B. C., Sageser, D. S., Rao, N. V., Emi, M., and Hoidal, J. R. (1990) J. Biol. Chem. 265, 8198-8204) and may therefore directly participate in the extensive remodeling that follows acute lung injury. Because the tissue repair process occurs in an acute inflammatory setting, we investigated the effects of inflammatory mediators on urokinase-type plasminogen activator (u-PA) expression by pulmonary epithelial cells. We found that interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) upregulated PA activity in A549 human pulmonary epithelial cells. Biosynthetic labeling and immunoprecipitation showed that both cytokines caused marked accumulation of newly synthesized u-PA. Northern blot analyses demonstrated that both IL-1 beta and TNF-alpha induced relatively rapid accumulation of u-PA mRNA which did not require de novo protein synthesis and was substantially inhibited by glucocorticoids. Nuclear run-off transcription studies showed that both cytokines caused rapid transcriptional activation of the u-PA gene. While the effects of IL-1 beta and TNF-alpha were qualitatively similar, some differences emerged. Most notably, TNF-alpha led to a more sustained accumulation of u-PA mRNA than did IL-1 beta. In contrast to their effects on u-PA expression, IL-1 beta and TNF-alpha had minimal effect on PA inhibitor-1 expression. These effects of IL-1 beta and TNF-alpha, mediators known to play a key role in acute lung injury and inflammation, may promote lysis of alveolar fibrin by alveolar epithelium, thereby aiding in restoration of normal lung architecture.

Blotting, Northern↗
PubMed1992

Coaches. A missing link in the health care system.

The number of children and adolescents who participate in interscholastic athletics demands attention to the quality of the coaching they receive and to the opportunities that the athlete-coach relationship provides for modification of high-risk behaviors, social skills training, and character formation. Although the need for coaches has increased due to the advent of girls' athletic programs, which was mandated by Title IX legislation, only a minority of states require certification for coaches who work in school systems. Four coaching curricula are summarized and contrasted: the American Coaching Effectiveness Program, the curriculum of the National Youth Sports Coaches Association, the Athletic Health Care System, and the Coach Effectiveness Training Program. Recommendations for coach certification by states, physician advocacy for coaching standards, and improved sports medicine services are discussed.

Faculty↗