Sexual differentiation of behaviour in monkeys: role of prenatal hormones.

The theoretical debate over the relative contributions of nature and nurture to the sexual differentiation of behaviour has increasingly moved towards an interactionist explanation that requires both influences. In practice, however, nature and nurture have often been seen as separable, influencing human clinical sex assignment decisions, sometimes with disastrous consequences. Decisions about the sex assignment of children born with intersex conditions have been based almost exclusively on the appearance of the genitals and how other's reactions to the gender role of the assigned sex affect individual gender socialisation. Effects of the social environment and gender expectations in human cultures are ubiquitous, overshadowing the potential underlying biological contributions in favour of the more observable social influences. Recent work in nonhuman primates showing behavioural sex differences paralleling human sex differences, including toy preferences, suggests that less easily observed biological factors also influence behavioural sexual differentiation in both monkeys and humans. We review research, including Robert W. Goy's pioneering work with rhesus monkeys, which manipulated prenatal hormones at different gestation times and demonstrated that genital anatomy and specific behaviours are independently sexually differentiated. Such studies demonstrate that, for a variety of behaviours, including juvenile mounting and rough play, individuals can have the genitals of one sex but show the behaviour more typical of the other sex. We describe another case, infant distress vocalisations, where maternal responsiveness is best accounted for by the mother's response to the genital appearance of her offspring. Taken together, these studies demonstrate that sexual differentiation arises from complex interactions where anatomical and behavioural biases, produced by hormonal and other biological processes, are shaped by social experience into the behavioural sex differences that distinguish males and females.

Urinary cadmium elimination as a biomarker of exposure for evaluating a cadmium dietary exposure--biokinetics model.

The Cadmium Dietary Exposure Model (CDEM) utilizes national survey data on food cadmium concentrations and food consumption patterns to estimate dietary intakes in the U.S. population. The CDEM has been linked to a modification of the cadmium biokinetic model of Kjellström and Nordlberg (KNM) to derive predictions of kidney and urinary cadmium that reflect U.S. dietary cadmium intake and related variability. Variability in dietary cadmium intake was propagated through the KNM using a Monte Carlo approach. The model predicts a mean peak kidney cadmium burden of approximately 3.5 mg and a 5th-95th percentile range of 2.2-5.1 mg in males. The corresponding peak renal cortex cadmium concentration in males is 15 microg/g wet cortex (10-22, 5th-95th percentile). Predicted kidney cadmium levels in females were higher than males: 5.1 (3.3-7.6) mg total kidney, 29 (19-43) microg/g wet cortex. Predicted urinary cadmium in males and females agreed with empirical estimates based on the NHANES III, with females predicted and observed to excrete approximately twice the amount of cadmium in urine than males. An explanation for the higher urinary cadmium excretion in females is proposed that is consistent with the NHANES III data as well as experimental studies in humans and animals. Females may absorb a larger fraction of ingested dietary cadmium than males, and this difference may be the result of lower iron body stores in females compared to males. This would suggest that females may be at greater risk of developing cadmium toxicity than males. The predicted 5th-95th percentile values for peak kidney cadmium burden are approximately 60% of the peak kidney burden (8-11 mg) predicted for a chronic intake at the U.S. Environmental Protection Agency (EPA) chronic reference dose of 1 microg/kg-d.

Screening for asymptomatic deep vein thrombosis in surgical intensive care patients.

PURPOSE: To identify the presence of occult deep vein thrombosis (DVT) in surgical intensive care unit (SICU) patients and to avoid unnecessary screening, we reviewed our experience with routine duplex screening for DVT in SICU patients. METHODS: Over a 24-month period, all patients who were admitted to an SICU with an anticipated length of stay greater than 36 hours were studied to determine the prevalence of risk factors for asymptomatic proximal DVT. Risk factors, demographics, and operative data were collected and analyzed with multilinear regression, t tests and chi 2 analysis. RESULTS: There was a 7.5% prevalence of major DVT in the 294 patients studied. APACHE II scores (14.5 +/- 6.24 vs 10.3 +/- 3.15; p < 0.0001) and emergent procedures (45.5% vs 23.2%; p > 0.0344) were associated with DVT by multifactorial analysis. Age was significant by univariate analysis. An algorithm based on the presence of any one of the three risk factors identified (APACHE II score 12 or more; emergent procedures; or age 65 or greater) could be used to limit screening by 30% while achieving a 95.5% sensitivity for identification of proximal DVT. CONCLUSION: Absence of all three risk factors indicates a very low risk for DVT (1.1%). Screening of SICU patients is indicated because of a high prevalence of asymptomatic disease. Patients who have proximal DVT require active therapy and not prophylaxis. Costs and resources may be contained by using the above risk factors as a filter for duplex screening.

Assessing antibacterial pharmacoeconomics in the intensive care unit.

Intensive care units (ICUs) represent areas of high use of antibacterials and other pharmacy goods and services. Many institutions view their ICUs as a target for drug-use surveillance and cost-containment programmes. Economic assessment of antibacterial interventions in the ICU should include all direct costs and patient outcomes. Nonetheless, many of these institutions focus their efforts at reducing antibacterial costs without considering the consequences of these actions. It is possible that devoting more resources to antibacterials can have an overall positive economic impact if more appropriate antibacterial use reduces length of stay, decreases bacterial resistance or lowers frequency of adverse complications. Two consequences of antibacterial use which can result in substantial economic burdens to institutions are drug-induced complications (toxicities and adverse events) and the development of antibacterial-resistant organisms. These events are logical targets for performing pharmacoeconomic studies to evaluate appropriate and inappropriate antibacterial use. Either of these problems can increase length of stay, which is the single most important variable influencing the overall cost of patient care. The primary goal of patient care is to hasten patients' clinical improvement. This will result in decreased antibacterial acquisition costs, decreased lengths of ICU and hospital stays, and ultimately decreased consumption of hospital resources. These can be accomplished by using strategies to guide antibacterial use in order to reduce failures, adverse events, toxicity and antimicrobial resistance.

Early tracheostomal healing in rabbits with use of various tracheal incisions.

Various tracheal incisions (vertical, horizontal, or window) are used by surgeons for creation of a tracheostomy. The inflammatory response and healing varies with each incision and may contribute to complications such as tracheal stenosis. This study evaluates the effect of these tracheotomies on early stomal wound healing in a rabbit model. Male juvenile New Zealand rabbits underwent tracheotomy, with each animal randomized to the type of tracheal incision used (vertical, horizontal, or window). After recovery, they were killed on postoperative days 2, 4, 6, and 8, with tissue removed for histologic examination. Paraffin-embedded stomal sections were analyzed quantitatively for amounts of granulation tissue, fibrosis, and epithelization. Groups were compared statistically using chi-square, ANOVA, Spearman's rho, and Mann-Whitney U tests with p less than 0.05 considered significant. Fibrosis was significantly increased in the vertical and horizontal groups when compared with the window group. This increase was statistically significant between postoperative days 2 and 4 (p < 0.05). The amount of granulation tissue was only significantly increased in the window group, whereas no difference was seen in the rate at which epithelization occurred with the various incisions. Vertical and horizontal tracheal wounds have less granulation tissue formation and more fibrosis compared with window tracheotomies during initial wound healing. This could lead to a "safer" tracheostomy tract in the early postoperative period.

Lesion width as a discriminator of plaque characteristics.

This study evaluated the relative ability of two techniques to quantify carotid atheroma. Diameter stenosis and lesion width were used to predict clinical significance and morphologic characteristics of 54 carotid endarterectomy specimens. Diameter stenosis was a better predictor of symptoms than lesion width (P=0.03 versus P=0.085). Both parameters were predictive of complex atheroma (diameter stenosis P=0.000; lesion width P=0.03). However, use of lesion width allowed finer definition of categories permitting more precise subclassification of plaque. This resulted in a better correlation of symptoms to complexity when lesion width was used as the discriminating variable (lesion width P=0.04; diameter stenosis P=0.121). Lesion width is a valuable parameter for the classification of carotid atheroma, correlating with symptoms and plaque complexity. Lesion width should be evaluated in future studies of carotid atheroma. The discriminative ability of lesion width as detected by high-resolution ultrasonography needs to be evaluated.

Small bowel injuries: mechanisms, patterns, and outcome.

OBJECTIVES: To determine the relationship between mechanism of injury (MI), operative management (OM), and outcome for traumatic jejunal and ileal wounds using an aggressive diagnostic, therapeutic, and support protocol. METHODS: Medical records for patients discharged with small bowel injuries from the Trauma Service between 1988 and 1992 were reviewed. The MI, presence of shock, method of diagnosis, OM, morbidity, and mortality were analyzed. RESULTS: Seventy patients had jejunal and/or ileal injuries. Blunt mechanisms caused injury in 33%, whereas the rest were penetrating wounds. Twenty-one diagnostic peritoneal lavages facilitated diagnosis (71% positive by tap). Ninety-six percent of the patients were explored within 3 hours of admission. Multiple perforations of jejunum were the most common injury of the small bowel. Using the Organ Injury Scale, grade III and IV wounds were statistically more common with penetrating injuries. Most of the injuries were managed with resection and stapled anastomosis, even in the presence of shock. CONCLUSIONS: There is a significant difference in MI and OM for small bowel wounds. Resection and stapled anastomosis is safe even in the presence of shock. Mortality and morbidity are related to associated injuries.

Risk factors for stroke after cardiac surgery: Buffalo Cardiac-Cerebral Study Group.

PURPOSE: The purpose of this study was to identify risk factors for stroke in patients undergoing heart surgery. METHODS: A retrospective chart review of patients who underwent cardiac surgery in three hospitals of the State University of New York at Buffalo system over a 36-month period was completed. Demographics and risk factors were recorded, and stroke and death were determined by chart review. Carotid artery stenosis was determined by duplex examination. Data were analyzed by chi-squared and multiple logistic regression. RESULTS: One thousand one hundred seventy-nine cases were analyzed, with a mortality rate of 2.3%, stroke rate of 1.6%, and combined stroke/death rate of 3.1%. Four variables were found to be associated with an increased risk of stroke: carotid artery stenosis greater than 50%, redo heart surgery, valve surgery, and prior stroke. Five variables were associated with increased mortality rates:; carotid artery stenosis greater than 50%, redo surgery, peripheral vascular disease, longer pump time, and hypercholesterolemia. Carotid artery stenosis greater than 50% was present in 14.7% of cases. Carotid artery stenosis greater than 75% was not itself associated with increased stroke risk. Most strokes occurred more than 24 hours after surgery. Stroke distribution did not correlate with site of carotid artery stenosis greater than 50%. CONCLUSIONS: Most neurologic events after heart surgery occur in a subset of patients who can be defined before operation. Whereas carotid artery stenosis greater than 50% is a strong risk factor, the role of prophylactic endarterectomy is unclear. Future studies should focus on this high-risk subgroup. A prospective study of prophylactic carotid endarterectomy in patients undergoing coronary artery bypass grafting is needed.

Evaluation of the pediatric surgical matching program by the directors of pediatric surgical training programs.

In a previous survey of successful candidates (SC) and unsuccessful candidates (USC) to the pediatric surgery matching program (PSMP), significant discriminating factors associated with SC included previous participation in basic science research, number of publications, number of national presentations, and contact with and letters of recommendation from well-known pediatric surgeons. The purpose of this study was to determine the selection criteria used by directors of the pediatric surgery training programs (PSTP) in choosing residents for the PSMP. A two-part survey of the PSMP was completed by directors of the PSTP (n = 24) to identify the factors (n = 31) that most influence their selection process when choosing a resident, and to help clarify questions (n = 11) posed by the candidates during the first survey. In part I, each factor was scored on a modified Likert Scale, from most (1) to least (5) important in evaluating candidates for training positions, and were ranked according to the mean score. Based on our previous survey, but blinded to the PSTP director respondents, these same factors were divided into groups that, in our first survey, did and did not discriminate between SC and USC for the PSMP, and will be referred to as "discriminating factors" (DF, n = 7) and "non-discriminating factors" (NDF, n = 8), respectively. Also, a series of questions dealt with subjective factors of the candidates, not previously analyzed in our original survey, and will be referred to as "program directors' factors" (PDF, n = 16). The three groups (DF, NDF, PDF) were analyzed by the Kruskal-Wallis test and analysis of variance (ANOVA).(ABSTRACT TRUNCATED AT 250 WORDS)

Prospective evaluation of epidural versus intrapleural catheters for analgesia in chest wall trauma.

Severe blunt chest trauma can produce multiple rib fractures, flail segments, and pulmonary contusions. All of these injuries produce pain and diminished pulmonary function. The effectiveness of intrapleural and epidural administration of bupivacaine was prospectively evaluated in 19 patients with severe chest trauma. Pain relief and pulmonary function were evaluated for 72 hours after catheter placement. Epidural administration of bupivacaine significantly reduced pain at rest and with motion compared with the intrapleural route (p < 0.05). Parenteral narcotic use was also significantly less in the epidural group (p < 0.05). Negative inspiratory pressure and tidal volume were significantly increased with epidural anesthesia (p < 0.05). Vital capacity, FIO2, minute ventilation, and respiratory rate were not affected. Mild hypotension was a common complication with epidural catheters. We conclude that continuous epidural analgesia is superior to intrapleural block and significantly improves tidal volume and negative inspiratory pressure.

Colon cancer in blacks: age-related presentation and survival within a similar socioeconomic group.

Young blacks with colon cancer continue to have a poor survival rate for reasons that remain undetermined. Medical records of blacks with colon cancer diagnosed at an inner-city hospital during a 10-year period were reviewed. The cohort consisted of 118 indigent, nonmigratory patients grouped by age. Group 1 consisted of 11 patients under age 50, and group 2 consisted of 107 patients age 50 and over. Admission symptoms were significantly different between groups. Patients in group 1 presented with abdominal pain more often than patients in group 2, and none of the patients in group 1 had anemia or obstruction, which comprised 14% and 11%, respectively, of the presenting symptoms in group 2 patients. Overall, survival difference was significant; the survival rate was 22.8 months for group 1 and 64.2 months for group 2 (P < .02). There was no difference in stage at presentation to account for the decreased survival in group 1. It is possible that the overwhelming majority (45%) of patients in group 1 with abdominal pain actually had more virulent disease, which accounts for the short survival. These individuals must be targeted for more aggressive patient education, surveillance, early detection and treatment, and follow-up.

Endocrine organ metastases in subjects with lobular carcinoma of the breast.

OBJECTIVE: To define the frequency and pattern of endocrine organ metastases in patients dying of invasive lobular carcinoma. DESIGN: Postmortem microscopic evaluation of the ovaries and adrenal, pituitary, thyroid, and parathyroid glands for breast cancer metastases. SETTING: Roswell Park Cancer Institute, Buffalo, NY, between 1971 and 1990. SUBJECTS: One hundred eighteen subjects who died of their cancer: 86 had infiltrating ductal carcinoma; 32, invasive lobular carcinoma. MEAN OUTCOME MEASURE: Quantitative measurements to allow frequency determinations and statistical comparisons. RESULTS: Endocrine organ metastases were found in 91% of the subjects with invasive lobular carcinoma vs 58% of subjects with infiltrating ductal carcinoma. The adrenal gland was most frequently involved. Multiple endocrine metastases were most common in the group with invasive lobular carcinoma. CONCLUSIONS: A relationship exists between invasive lobular carcinoma and endocrine metastases. This indicates that antemortem endocrine evaluation may subsequently improve quality-of-life treatment.

Colonoscopic impaction in left colon strictures resulting in right colon pneumatic perforation.

Colonic perforation during flexible colonoscopy is a rare but recognized complication. We reviewed 4,593 colonoscopies performed from 1984 to 1989. The perforation rate for diagnostic colonoscopy was 0.17% (6/3,538) and for therapeutic colonoscopy it was 2% (21/1,055). Four perforations of the right colon occurred at a site proximal to the level of the impacted colonoscope. The lesions being evaluated were obstructive in nature: two diverticular strictures (sigmoid colon), one ischemic stricture (descending colon), and one annular carcinoma (descending colon). The four perforations occurred in the right colon and manifested as distension with pneumoperitoneum or retroperitoneal emphysema. Operative management included total abdominal colectomy in two patients (ileoproctostomy in one and ileostomy in one) and right colectomy in two. Outcome was favorable in all cases.

Experience as a surgeon determines resident knowledge.

BACKGROUND: This is a prospective study that compares operative experience with performance on the American Board of Surgery Inservice Training Examination (ABSITE) to establish the primacy of procedural experience in the graduate training environment. METHODS: Operative experience was determined from a computerized log of surgical procedures. The Report D of the 1991 ABSITE was used to assign each test item to specific operative procedures and to determine the frequency of the correct response (Fcr) for each item. The fraction of operative procedures (Fs) was determined for each category of surgical procedures (Fs = Number of procedures as surgeon/Total number of procedures). The Fcr was compared to the Fs by use of the Pearson correlation coefficient with significance at 95% confidence. RESULTS: Forty-two residents reported doing 8357 surgical procedures as surgeon in 12 months. Report D contained 209 test items. Of these, 162 items could be assigned to 26 categories of surgical procedures. The Fcr correlated directly with the Fs (p = 0.002, r = 0.605). CONCLUSIONS: A significant correlation exists between the experience of surgical residents as surgeon and their performance on the ABSITE:

Comparative analysis of successful and unsuccessful candidates for the pediatric surgical matching program.

Only one third of the applicants for training in pediatric surgery obtain a position through the pediatric surgery matching program. In order to identify factors that contribute to a successful outcome, we conducted a retrospective survey of all participants in the matching process for positions during the years 1983 to 1991. This survey was designed to identify characteristics associated with success in the match through comparison of successful and unsuccessful applicants. Significant factors associated with a successful match included: a greater incidence of residency-supported research (P = .012) with a greater number of publications (P = .003) and national presentations (P = .014), specifically at the annual meetings of the American Pediatric Surgical Association (P = .05) and the American Academy of Pediatrics (P = .05). In addition, successful candidates had more contact with (P = .004) and letters of recommendation from (P = .015) well-known pediatric surgeons involved in the general surgical residency program. This information should be invaluable to those counseling medical students and residents interested in a career in pediatric surgery.

Liver lacerations--a marker of severe but sometimes subtle intra-abdominal injuries in adults.

Experience with conservative management of solid viscus injuries from abdominal trauma in children has produced the impetus for a similar management in adults. To explore the implications of such a policy, we reviewed the records of 82 patients with hepatic injuries noted at laparotomy. Indications for laparotomy were positive findings on diagnostic peritoneal lavage (DPL) or CT scan, or a history of penetrating trauma. The liver injuries were graded according to severity: grade I, 19 patients; grade II, 20 patients (low severity = LS); grade III, 14 patients; grade IV, 6 patients (high severity = HS). Twenty-three injuries were not classified by the operating surgeon. Of the 53 patients with blunt hepatic trauma, 23 (43%) had concomitant injuries that required operative intervention. Twenty-nine patients had penetrating liver injuries. Fourteen (48%) had associated injuries requiring intervention. Patients most likely to have nonoperative management, those with grade I and grade II liver injuries (LS), comprised 48 of the total. In this subgroup there were 26 (54.2%) associated injuries requiring operative intervention. Shock could not be used as a factor to differentiate patients not requiring operative intervention. Nineteen of the LS patients requiring operative intervention secondary to associated injury were never in shock. In adult trauma victims positive DPL findings secondary to minor hepatic injuries that might not require operative intervention serve as a marker for associated injuries that do require operation. The risk of nonoperative management of hepatic injuries based upon radiologic diagnosis is not the result of complications from the hepatic injury.(ABSTRACT TRUNCATED AT 250 WORDS)