Predicting the response of a long-distance migrant to changing environmental conditions in winter.

Access to high-quality food is critical for long-distance migrants to provide energy for migration and arrival at breeding grounds in good condition. We studied effects of changing abundance and availability of a marine food, common eelgrass (Zostera marina L.), on an arctic-breeding, migratory goose, black brant (Brant bernicla nigricans Lawrence 1846), at a key non-breeding site, Bahía San Quintín, Mexico. Eelgrass, the primary food of brant, is consumed when exposed by the tide or within reach from the water's surface. Using an individual-based model, we predicted effects of observed changes (1991-2013) in parameters influencing food abundance and availability: eelgrass biomass (abundance), eelgrass shoot length (availability, as longer shoots more within reach), brant population size (availability, as competition greater with more birds), and sea level (availability, as less food within reach when sea level higher). The model predicted that the ability to gain enough energy to migrate was most strongly influenced by eelgrass biomass (threshold January biomass for migration = 60 g m-2 dry mass). Conversely, annual variation in population size (except for 1998), was relatively low, and variation in eelgrass shoot length and sea level were not strongly related to ability to migrate. We used observed data on brant body mass at Bahía San Quintín and annual survival to test for effects of eelgrass biomass in the real system. The lowest observed values of body mass and survival were in years when biomass was below 60 g m-2, although in some years of low biomass body mass and/or survival was higher. This suggests that the real birds may have some capacity to compensate to meet their energy demands when eelgrass biomass is low. We discuss consequences for brant population trends and conservation.

FishMORPH - An agent-based model to predict salmonid growth and distribution responses under natural and low flows.

Predicting fish responses to modified flow regimes is becoming central to fisheries management. In this study we present an agent-based model (ABM) to predict the growth and distribution of young-of-the-year (YOY) and one-year-old (1+) Atlantic salmon and brown trout in response to flow change during summer. A field study of a real population during both natural and low flow conditions provided the simulation environment and validation patterns. Virtual fish were realistic both in terms of bioenergetics and feeding. We tested alternative movement rules to replicate observed patterns of body mass, growth rates, stretch distribution and patch occupancy patterns. Notably, there was no calibration of the model. Virtual fish prioritising consumption rates before predator avoidance replicated observed growth and distribution patterns better than a purely maximising consumption rule. Stream conditions of low predation and harsh winters provide ecological justification for the selection of this behaviour during summer months. Overall, the model was able to predict distribution and growth patterns well across both natural and low flow regimes. The model can be used to support management of salmonids by predicting population responses to predicted flow impacts and associated habitat change.

Expression of the insulin-like growth factor (IGF)-I and -II and the IGF-I and -II receptor genes during postnatal development of the rat ovary.

Solution hybridization/RNase protection assays were used to study the developmental expression of the insulin-like growth factor-I (IGF-I), IGF-II, IGF-I receptor, and IGF-II/mannose-6-phosphate receptor genes in the rat ovary between postnatal days 1-80. Maximal IGF-I mRNA levels occurred during the 15- to 25-day postnatal period, and the level on day 20 represented a 9-fold increase over the baseline at earlier and later stages. IGF-II mRNA levels were maximal during the 1- to 5-day postnatal period and subsequently declined to undetectable levels after day 10. IGF-I receptor mRNA levels increased 10-fold to a maximum in the 20- to 25-day postnatal period. This pattern was similar to the developmental pattern of [125I]IGF-I binding in the ovary. Two apparent peaks of IGF-II/mannose-6-phosphate receptor mRNA levels were seen, on day 20 and between days 50-80. These specific and significant changes in the expression of the genes encoding the IGFs and their receptors suggest a role for the IGF system in postnatal ovarian development.

The psychedelic model of schizophrenia: the case of N,N-dimethyltryptamine.

The authors review the research on N,N-dimethyltryptamine (DMT) as a possible "schizotoxin." DMT produces psychedelic effects when administered to normal subjects, the means are present to synthesize it in man, it has occasionally been found in man, and tolerance to its behavioral effects is incomplete. However, DMT concentrations have not been proven to differ significantly in schizophrenics and normal controls. Also, in vivo synthesis of DMT has not been convincingly demonstrated, and the psychological changes it produces do not closely mimic the symptoms of schizophrenia. The authors conclude that more data are necessary before the validity of this theory can be determined.

Altered lateralization of cognitive processes in depressed women.

Eighteen normal men and women had a left hemisphere advantage for processing a verbal task, but depressed women showed a trend toward right hemisphere superiority. In depression the right hemisphere may share functions performed exclusively by the left hemisphere in normal subjects. Altered laterality may be a trait of depression-prone people or a change related to depressive episodes themselves. In the latter case, the right hemisphere may be compensating for relative deactivation of the dominant left hemisphere.

Soy protein and isoflavones: their effects on blood lipids and bone density in postmenopausal women.

The effects of soy protein (40 g/d) containing moderate and higher concentrations of isoflavones on blood lipid profiles, mononuclear cell LDL receptor messenger RNA, and bone mineral density and content were investigated in 66 free-living, hypercholesterolemic, postmenopausal women during a 6-mo, parallel-group, double-blind trial with 3 interventions. After a control period of 14 d, during which subjects followed a National Cholesterol Education Program Step I low-fat, low-cholesterol diet, all subjects were randomly assigned to 1 of 3 dietary groups: Step I diet with 40 g protein/d obtained from casein and nonfat dry milk (CNFDM), Step I diet with 40 g protein/d from isolated soy protein containing 1.39 mg isoflavones/g protein (ISP56), or Step I diet with 40 g protein/d from isolated soy protein containing 2.25 mg isoflavones/g protein (ISP90). Total and regional bone mineral content and density were assessed. Non-HDL cholesterol for both ISP56 and ISP90 groups was reduced compared with the CNFDM group (P < 0.05). HDL cholesterol increased in both ISP56 and ISP90 groups (P < 0.05). Mononuclear cell LDL receptor mRNA was increased in subjects consuming ISP56 or ISP90 compared with those consuming CNFDM (P < 0.05). Significant increases occurred in both bone mineral content and density in the lumbar spine but not elsewhere for the ISP90 group compared with the control group (P < 0.05). Intake of soy protein at both isoflavone concentrations for 6 mo may decrease the risk factors associated with cardiovascular disease in postmenopausal women. However, only the higher isoflavone-containing product protected against spinal bone loss.

A comparison of bone mineral densities among female athletes in impact loading and active loading sports.

The purpose of this study was to compare bone mineral densities (BMD) of collegiate female athletes who compete in impact loading sports; volleyball players (N = 8) and gymnasts (N = 13), to a group of athletes who participate in an active loading sport; swimmers (N = 7), and a group of controls (N = 17). All of the volleyball, swimming, and control subjects were eumenorrheic (10-12 cycles/year), whereas two of the gymnasts were amenorrheic (0-3 cycles/year), eight were oligomenorrheic (4-8 cycles/year), and three were eumenorrheic (10-12 cycles/year). Lumbar spine, proximal femur, and total body BMD were measured with dual-energy X-ray absorptiometry. The groups were compared with respect to the following regions: lumbar spine (L1-4); femoral neck; Ward's triangle; right and left arms; right and left legs; pelvis; and torso. When controlling for differences in height and weight the impact loading group (volleyball and gymnastic) had significantly greater BMD at the lumbar spine, femoral neck, Ward's Triangle, and total body when compared to the active loading (swimming) and control groups. The regional analysis from the total body scan revealed that the gymnasts had significantly (p < 0.05) greater BMD than all other groups at the right and left arm sites. The impact loading groups (gymnastic and volleyball) had a greater BMD in the legs and pelvis than the active loading (swimming) and control groups. Furthermore, the impact loading group had a greater torso BMD than the control group. There were no differences at any site between the active loading group (swimming) and control groups.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of alcohol abuse on perceptual reference frames.

Visuospatial processing in alcoholics was investigated by aligning two elements along different axes of an equilateral triangle and asking subjects to report the direction the triangle appeared to point when first observed. Alcoholics were not as affected as controls by alignment of the elements. The implications of these findings are discussed.

When enough is not enough: shorebirds and shellfishing.

In a number of extensive coastal areas in northwest Europe, large numbers of long-lived migrant birds eat shellfish that are also commercially harvested. Competition between birds and people for this resource often leads to conflicts between commercial and conservation interests. One policy to prevent shellfishing from harming birds is to ensure that enough food remains after harvesting to meet most or all of their energy demands. Using simulations with behaviour-based models of five areas, we show here that even leaving enough shellfish to meet 100% of the birds' demands may fail to ensure that birds survive in good condition. Up to almost eight times this amount is needed to protect them from being harmed by the shellfishery, even when the birds can consume other kinds of non-harvested prey.

Intramural lymphatic cyst of bovine heterograft.

An intramural lymphatic cyst of a bovine heterograft is described. This previously unreported complication presented as a pulsatile mass in the thigh of an 84-year-old woman who had undergone vascular reconstruction 12 months previously. The clinical presentation, operative findings, and pathological findings are described, and the management of the case is discussed.

Improved performance 4 hours after cocaine.

Cocaine (2 mg/kg) was given orally to 13 healthy volunteers and physiologic, subjective, attentional and performance effects were measured over a period of 4 h. Posner's reaction time paradigm measured the effects of cocaine on performance and on attention to visual cues. Cocaine increased heart rate, systolic blood pressure and pupil diameter and reduced skin temperature. Physiologic effects, subjective rating of intoxication, and cocaine levels in saliva peaked at approximately 75 min and returned to precocaine levels within 3 h. In contrast, a reaction time measure of performance speed on the visual attention task showed improvement for 4 h after cocaine. A measure of covert attention in the cocaine condition failed to show the improvement which occurred in the placebo condition. Less fatigue was reported 4 h after cocaine than after placebo. Cocaine users may experience the drug's stimulant effects considerably longer than the euphoriant effects.

Retrograde enhancement of human memory with alcohol.

In two experiments with normal male subjects, the ingestion of alcohol (1 ml/kg) immediately after learning significantly improved subsequent remembering. By comparison, marijuana (15 mg) had no significant post-acquisition effect. Facilitation of visual and verbal memory with alcohol under these conditions has implications for the interference and consolidation views of memory.

The alcohol facilitation effect on memory: a dose-response study.

Sixteen normal male subjects participated in four sessions where they studied a set of pictures followed by either placebo, 0.025, 0.50, or 1.0 ml/kg alcohol. Later, when sober, recognition memory was tested. These doses resulted in peak blood alcohol concentrations (BAC) of 0.00, 0.018, 0.034, and 0.067 g/100 ml, respectively. The 1.0 and 0.50 ml/kg doses significantly improved memory for pictures studied before drinking. Alcohol appears to enhance memory directly rather than indirectly via a reduction in interference. It is suggested that a particular phase of the rising blood alcohol curve (0.02-0.03 g/100 ml) facilitates trace consolidation. The facilitating and possibly excitatory effects of alcohol may be important for understanding the rewarding aspects of drinking.

Validity of multiple-choice examinations in surgery.

The difficulty of creating new, unambiguous, pertinent multiple-choice questions of a level appropriate to medical students implies that examinations must be compiled from a limited number of items. Furthermore, it is impossible to keep used questions inaccessible to all subsequent students. This study was undertaken to determine if these realities are compatible with examinations that are both valid and reliable. A pool of 480 multiple-choice questions was distributed to 232 students during the surgical clerkship. At the conclusion of each quarter, a 120-item multiple-choice examination that consisted of entirely new questions was administered (group I). These 960 questions were then made available to the next group of 218 students; each subsequent examination consisted of 50% new questions and 50% questions repeated verbatim from the publicized pool (group II). With the available pool now increased to 1200, the next examination consisted of 20% new and 80% repeat questions (group III). Reliability (internal consistency) was measured by the Kuder-Richardson-21 formula. Validity was measured by correlation between the multiple-choice examination and the average score of evaluations of each student by two oral examinations and five faculty members. Despite the expected increase in mean examination score, there is loss of neither reliability nor validity by inclusion of even 80% of items repeated from a large pool of multiple-choice questions that have been distributed to the students. Hence, instead of adding irrelevant, trivial, or inappropriate items or trying in vain to hide old examinations from new students, simple preparation of examinations from a large pool of questions is recommended. To insure fairness to all students, this pool should be made public knowledge.

Pitfalls in evaluating the surgical student.

One hundred five students in our surgical clerkship were evaluated independently by two faculty members, a chief resident, a written multiple-choice examination, and two oral examinations. Faculty and chief resident evaluations included a written explanation and a score from 1 (honors) to 5 (failing). Oral and written examination scores were adjusted to the same numerical scale. Correlation coefficients (r) and probabilities (P) by the t test were calculated to determine validity of the components of the students' grades. In comparison with the oral examination, written examination, and final mean score, the chief residents' evaluations exhibited a validity significantly lower than that of both faculty groups (P less than 0.01). This finding was associated with the following differences in content of associated written evaluations. Residents were more likely to mention "skills" or "technique" (P less than 0.001) and less likely to comment on "logic," "judgment," or "reasoning" (P less than 0.001). Comments concerning "appearance," "enthusiasm," "diligence," and "motivation" were not significantly different among these groups. Experience gained as a member of a surgical teaching faculty or by an affiliation with a teaching program resulted in a greater tendency to focus on thought processes and less emphasis on technical factors in the evaluation of the student on a surgical rotation. Education of surgical house staff must include elucidation of appropriate criteria by which students should be judged. A welcome by-product might be a shift in emphasis in surgical education from a myriad of technical details to a logical approach to diagnosis and treatment.

Effect of prior clinical experience on students' knowledge and performance in surgery.

Approaches to designing an optimal surgical curriculum and studies of validity and reliability of students' evaluations have neglected the potential effect of prior clinical experience, although this admittedly increases greatly from those entering surgery as the first clinical clerkship to those taking surgery after completion of all other clinical rotations. The present study assesses students' knowledge on entering the surgery clerkship, reevaluates knowledge, assesses performance on completion of the surgery clerkship, and determines the effect of prior clinical experience on both knowledge and performance. Four hundred fifty consecutive students were evaluated during 2 academic years with a 100-question multiple-choice pretest, posttest, two oral examinations, and three subjective evaluations by surgical faculty members and housestaff. Reliability of the multiple choice examinations averaged 0.70 as determined by the KR-21 coefficient. Both mean pretest and posttest scores decreased with increasing clinical experience, mainly due to loss of preclinical knowledge. Nevertheless, scores on subjective evaluations increased. Regression analysis demonstrated positive intercorrelation among the subjective evaluations but no correlation to the objective forms of evaluation. It is suggested that multiple-choice examinations lack the ability to assess clinical competence and decision-making skills, qualities that are better evaluated by faculty members. The efficiency of teaching methods and the fairness of final grades may benefit from recognition of the effects of prior clinical rotations.

Evaluation of the student: improving validity of the oral examination.

Medical students completing a surgical clerkship were scored independently by faculty members, a chief resident and a written multiple-choice examination. In group I, an oral examination was administered by two faculty members together in one room, while in group II, the examiners were in separate rooms. The average oral examination grade correlated with none of the other facets of the student evaluation in group I, but did so for most parameters in group II. The correlation coefficient between the oral examination and mean grade became significant, however, for oral examinations in which five or more core topics were covered. It is concluded that even with limited professional resources, changes in the method of administering an oral examination can increase its validity.

Results of renal transplantation using pediatric cadaver donors.

In order to determine the results of transplantation using pediatric cadaver donors, a retrospective analysis of a series of 502 renal transplant recipients was carried out. Methods of procurement, preservation, recipient selection, and immunosuppressive regimen were similar for all patients. Sixty-five recipients were approximately equally divided into three groups whose donors were younger than 5 years of age, 6 to 10 years old, and 11 to 15 years. These three groups then were compared with each other and to a randomly selected representative group of recipients whose donors were adults (16 years or older) for the following parameters: actuarial graft and patient survival, causes of graft failure and patient death, level of serum creatinine in currently functioning grafts, and recipient age. There were no statistically significant differences between groups for any parameter except that the mean age of recipients was approximately 16 years for the donors up to 5 years of age and was between 31 and 36 years for the other donor age groups (P = 0.01). These results support the contention that brain-dead pediatric patients of any age should be considered to be potential cadaveric kidney donors. Exclusion of these patients is very wasteful and also is unnecessary since results of transplantation equal to those obtained with adult donors can be expected. Technical graft failures should not be more frequent than with adult kidneys, and there is no need to modify the basic surgical technique for small kidneys in order to achieve this.

Determining the content of a surgical curriculum.

The purpose of undergraduate surgical education is to prepare the student for both the residency and eventual practice of medicine. To help determine the surgical knowledge and skills that would eventually the useful to the student, we conducted a survey of residents in training, physicians in practice, and surgical educators (department chairpersons and clerkship directors). Members of the Curriculum Committee of the Association for Surgical Education developed a questionnaire in which the respondents were asked to grade the functional importance of 84 areas of knowledge and 46 skills (0 = unnecessary, 3 = proficiency necessary). Using a modified Delphi technique to collect information, we sent the questionnaire to eight medical school graduation classes of 1975 (730 persons) and 1980 (776 persons) and all department chairpersons and/or clerkship directors (179). The results of the survey (46% response) revealed considerable agreement about the importance of certain skills and areas of knowledge, enabling us to rank order skills and knowledge based on mean responses (0.0 to 3.0). Physicians in practice, residents, and educators believed that certain areas of knowledge (e.g., acute abdominal problems, appendicitis, shock, cancer of the breasts) and skills (e.g., history taking and physical examination, gowning, suture removal) were very important (greater than 2.250, while other areas of knowledge (e.g., transplantation, liver abscess, soft tissue sarcomas) and skills (e.g., insertion of Swan-Ganz catheter, abdominal paracentesis, cricothyroidotomy) were less important (less than 1.3). This approach allows us to assign priorities to areas of knowledge and skills when determining curriculum content and to include functional criteria when developing educational objectives.

Association between mullerian duct malformations and Asherman syndrome in infertile women.

Mullerian duct malformations were found in 8% and Asherman syndrome in 4.8% of 537 infertile women undergoing hysterosalpingogram and/or hysteroscopy among 840 consecutive infertile couples evaluated. Among the 43 patients with mullerian duct malformations and the 26 with Asherman syndrome, seven had both mullerian duct malformations and Asherman syndrome (16 and 29%, respectively). This association was highly significant (P less than .005), especially for those patients with a septate uterus (P less than .001). Secondary infertility was present in 44% of the 840 infertile couples; 41% of the 537 women undergoing hysterosalpingogram and/or hysteroscopy and 44% of the patients with mullerian duct malformations versus 81% of those with Asherman syndrome (P less than .001). Prior reproductive performance was dismal for the patients with Asherman syndrome and/or mullerian duct malformations, and among all classes of mullerian duct malformations, and among all classes of mullerian duct malformations. The predisposing and causative factors leading to Asherman syndrome can be observed with mullerian duct malformations and a strong association in this population of infertile couples is reported for the first time.