Activation of androgen receptor-expressing neurons in the posterior medial amygdala is associated with stress resistance in dominant male hamsters.

Social stress is a negative emotional experience that can increase fear and anxiety. Dominance status can alter the way individuals react to and cope with stressful events. The underlying neurobiology of how social dominance produces stress resistance remains elusive, although experience-dependent changes in androgen receptor (AR) expression is thought to play an essential role. Using a Syrian hamster (Mesocricetus auratus) model, we investigated whether dominant individuals activate more AR-expressing neurons in the posterior dorsal and posterior ventral regions of the medial amygdala (MePD, MePV), and display less social anxiety-like behavior following social defeat stress compared to subordinate counterparts. We allowed male hamsters to form and maintain a dyadic dominance relationship for 12 days, exposed them to social defeat stress, and then tested their approach-avoidance behavior using a social avoidance test. During social defeat stress, dominant subjects showed a longer latency to submit and greater c-Fos expression in AR+ cells in the MePD/MePV compared to subordinates. We found that social defeat exposure reduced the amount of time animals spent interacting with a novel conspecific 24 h later, although there was no effect of dominance status. The amount of social vigilance shown by dominants during social avoidance testing was positively correlated with c-Fos expression in AR+ cells in the MePV. These findings indicate that dominant hamsters show greater neural activity in AR+ cells in the MePV during social defeat compared to their subordinate counterparts, and this pattern of neural activity correlates with their proactive coping response. Consistent with the central role of androgens in experience-dependent changes in aggression, activation of AR+ cells in the MePD/MePV contributes to experience-dependent changes in stress-related behavior.

Differences in NMDA receptor expression during human development determine the response of neurons to HIV-tat-mediated neurotoxicity.

HIV infection of the CNS can result in neurologic dysfunction in a significant number of infected individuals. NeuroAIDS is characterized by neuronal injury and loss, yet there is no evidence of HIV infection in neurons. Thus, neuronal damage and dropout are likely due to indirect effects of HIV infection of other CNS cells, through elaboration of inflammatory factors and neurotoxic viral proteins, including the viral transactivating protein tat. We and others demonstrated that tat induces apoptosis in differentiated mature human neurons. We now demonstrate that the high level of tat toxicity observed in human neurons involves specific developmental stages that correlate with N-methyl-D-aspartate receptor (NMDAR) expression, and that tat toxicity is also dependent upon the species being analyzed. Our results indicate that tat treatment of primary cultures of differentiated human neurons with significant amounts of NMDAR expression induces extensive apoptosis. In contrast, tat treatment induces only low levels of apoptosis in primary cultures of immature human neurons with low or minimal expression of NMDAR. In addition, tat treatment has minimal effect on rat hippocampal neurons in culture, despite their high expression of NMDAR. We propose that this difference may be due to low expression of the NR2A subunit. These findings are important for an understanding of the many differences among tissue culture systems and species used to study HIV-tat-mediated toxicity.

HIV tat and neurotoxicity.

HIV tat is the transactivator of HIV-1, supporting efficient viral replication by stabilizing the transcription of viral genes. Tat can be released from HIV-infected cells and alter several functions in uninfected cells. In the brain, tat induces neuronal dysfunction/toxicity, even though neurons cannot be directly infected with HIV, resulting in CNS pathology, such as the dementia and encephalitis associated with NeuroAIDS. This review discusses the most recent data addressing tat-induced neurotoxicity and integrates these new findings in the context of NeuroAIDS.

Sensitivity and specificity of immunohistochemical markers used in the diagnosis of epithelioid mesothelioma: a detailed systematic analysis using published data.

AIMS: Immunohistochemistry is frequently employed to aid the distinction between mesothelioma and pulmonary adenocarcinoma metastatic to the pleura, but there is uncertainty as to which antibodies are most useful. We analysed published data in order to establish sensitivity and specificity of antibodies used to distinguish between these tumours with a view to defining the most appropriate immunohistochemical panel to use when faced with this diagnostic problem. METHODS AND RESULTS: A systematic analysis of the results of 88 published papers comparing immunohistochemical staining of a panel of antibodies in mesothelioma with epithelioid areas, and pulmonary adenocarcinoma metastatic to the pleura. Results for a total of 15 antibodies were analysed and expressed in terms of sensitivity and specificity. The most sensitive antibodies for identifying pulmonary adenocarcinoma were MOC-31 and BG8 (both 93%), whilst the most specific were monoclonal CEA (97%) and TTF-1 (100%). The most sensitive antibodies to identify epithelioid mesothelioma were CK5/6 (83%) and HBME-1 (85%). The most specific antibodies were CK5/6 (85%) and WT1 (96%). CONCLUSIONS: No single antibody is able to differentiate reliably between these two tumours. The use of a small panel of antibodies with a high combined sensitivity and specificity is recommended.

U.S. Army dental emergency rates in Bosnia.

OBJECTIVE: Our objective is to report on overall dental emergency rates and rates by dental classification of a U.S. Army peacekeeping operation longer than 6 months in the year 2000. MATERIALS AND METHODS: This study was a retrospective cohort analysis of dental emergencies experienced by soldiers of the 3rd Armored Cavalry Regiment as a part of Stabilization Force VII. Before the deployment, all soldiers received dental examinations and the necessary dental treatment to make them class 1 or 2. A dental emergency was identified from field treatment records when a soldier presented to the clinic for a "sick call," emergency, or trauma visit. RESULTS: Retrospective review of the records identified 211 dental emergencies. Class 1 soldiers experienced 75 dental emergencies and class 2 soldiers experienced 136 emergencies. 3rd Armored Cavalry Regiment soldiers spent an average of 201.95 days deployed. The overall emergency rate was 156 dental emergencies per 1,000 soldiers per year. Class 1 and 2 rates were 121 and 185 dental emergencies per 1,000 troops per year, respectively. CONCLUSIONS: The results tend to confirm that dental emergencies continue to be a threat to overall readiness in deployed environments. Military planners need to ensure that the dental component of future forces are sufficient to care for the expected emergencies.

The heritability of personality factors in chimpanzees (Pan troglodytes).

Human personality and behavior genetic studies have resulted in a growing consensus that five heritable factors account for most variance in human personality. Prior research showed that chimpanzee personality is composed of a dominance-related factor and five human-like factors--Surgency, Dependability, Emotional Stability, Agreeableness, and Openness. Genetic, shared zoo, and nonshared environmental variance components of the six factors were estimated by regressing squared phenotypic differences of all possible pairs of chimpanzees onto 1 - Rij, where Rij equals the degree of relationship and a variable indicating whether the pair was housed in the same zoo. Dominance showed significant narrow-sense heritability. Shared zoo effects accounted for only a negligible proportion of the variance for all factors.

Familial adenomatous polyposis: results after ileal pouch-anal anastomosis in teenagers.

PURPOSE: Virtually all untreated patients with familial adenomatous polyposis develop colorectal carcinoma. Thus, prophylactic colectomy is indicated. Detractors of ileal pouch-anal anastomosis prefer ileorectal anastomosis for teenagers because of the potential negative impact of ileal pouch-anal anastomosis on quality of life. The aim of this study was to assess the effects on quality of life of ileal pouch-anal anastomosis in teenagers with familial adenomatous polyposis. METHODS: Between 1981 and 1998, 48 teenagers underwent ileal pouch-anal anastomosis for familial adenomatous polyposis. One patient had proctectomy and ileal pouch-anal anastomosis after previous ileorectal anastomosis. A temporary diverting loop ileostomy was established in 42 patients (87.5 percent). One patient had colonic carcinoma diagnosed preoperatively. Two other patients were found to have unsuspected rectal cancer at surgery. Mean follow-up (+/- standard deviation) in 43 patients was 80.5 +/- 42 months. RESULTS: There was no immediate postoperative mortality. Postoperative complications included pelvic sepsis (3 patients; 1 requiring reoperation) and bleeding (1 patient; no surgery required). One patient died of metastatic colonic carcinoma. Ten patients required reoperation, seven had bowel obstruction, one had portal hypertension, and two required an ileostomy. The mean (+/- standard deviation) daytime and nighttime stool frequency was 4 +/- 1.5 and 1 +/- 1, respectively. One patient reported daytime and nighttime incontinence, and two patients reported nighttime incontinence only. No patient experienced impotence or retrograde ejaculation. Social, sexual, sport, housework, recreation, family, travel, and work activities were improved or unchanged in 82.5, 87, 80, 90, 80, 92.5, 77.5, and 89 percent of patients, respectively. Three male patients fathered children, and three female patients had a total of six children after normal pregnancies and deliveries. CONCLUSION: The impact of ileal pouch-anal anastomosis on quality of life was favorable in the majority of teenagers. The risk of rectal cancer should be the major consideration before proposing an operation to teenagers with familial adenomatous polyposis.

Care of patients and their families with familial adenomatous polyposis.

Familial adenomatous polyposis (FAP) is a dominantly inherited disorder that is typically characterized by the appearance of multiple colorectal adenomas usually by the teenage years, with a risk of early colorectal cancer approaching 100%. Genetic testing can help determine which family members have the disorder and require surveillance endoscopy. Astute physicians may detect unsuspected FAP in patients with extraintestinal manifestations such as hard or soft cutaneous tumors. Colectomy will prevent cancer but is often necessary before the patient is 20 years old. Postoperative lifelong surveillance is indicated to screen for associated duodenal, thyroid, and rectal or ileal neoplasms. Attenuated FAP variants are less typical and may be confused with other types of familial colorectal neoplasia. Chemoprevention, regression, and other treatment strategies are being developed to improve the management of extracolonic neoplasms and desmoid tumors. A better understanding of the natural history of these FAP-associated phenomena will facilitate the rational selection of interventions. Management guidelines that were recently developed at Mayo Clinic Rochester to provide for uniform care and surveillance are discussed.

Nutritional status indicators and their interactions in rural Guatemalan elderly: a study in San Pedro Ayampuc.

Anthropometry and body-composition measures, hematologic and biochemical measures of nutritional status, and helminthic infection were studied in the population of elderly persons (> or = 60 y of age) in a rural village in Guatemala that was 65% Mayan (indigenous) and 35% ladino (European). The population had low levels of literacy and formal education. The elderly persons were much shorter and lighter than reference populations. Anemia was present in 18% of the population, and riboflavin and vitamin B-12 deficiencies were detected in 70% and 38%, respectively. Both anthropometric and biochemical-hematologic variables were lower, on average, in the Mayan descendants than in the ladinos. When grouped by body mass index (BMI; in kg/m2), greater BMI signified higher values for almost all biochemical-hematologic measures. Sixty-five percent of the sampled population had mild-to-moderate Ascaris lumbricoides and Trichuris trichiura infections. The lifestyle in rural Guatemala is evolving, and the present findings provide insights into the evolution of nutritional status in the growing number of elderly in the countryside.

Amino Acid Utilization in Seeds of Loblolly Pine during Germination and Early Seedling Growth (I. Arginine and Arginase Activity).

The mobilization and utilization of the major storage proteins in loblolly pine (Pinus taeda L.) seeds following imbibition were investigated. Most of the seed protein reserves were contained within the megagametophyte. Breakdown of these proteins occurred primarily following radicle emergence and correlated with a substantial increase in the free amino acid pool in the seedling; the majority of this increase appeared to be the result of export from the megagametophyte. The megagametophyte was able to break down storage proteins and export free amino acids in the absence of the seedling. Arginine (Arg) was the most abundant amino acid among the principal storage proteins of the megagametophyte and was a major component of the free amino acid pools in both the seedling and the megagametophyte. The increase in free Arg coincided with a marked increase in arginase activity, mainly localized within the cotyledons and epicotyl of the seedling. Arginase activity was negligible in isolated seedlings. Experiments with phenylphosphorodiamidate, a urease inhibitor, supported the hypothesis that arginase participates in Arg metabolism in the seedling. The results of this study indicate that Arg could play an important role in the nutrition of loblolly pine during early seedling growth.

Laterality in hand preferences and reaching accuracy of cotton-top tamarins (Saguinus oedipus).

Manual laterality of cotton-top tamarins (Saguinus oedipus) was observed for five different types of reaching. The tamarins displayed species-level right-handedness for spontaneous grasping for food but not for one-arm vertical suspension or any of 3 other types of elicited reaching. The results showed that difficult or novel tasks are neither necessary nor sufficient for the emergence of species-level handedness. Accuracy in retrieving food from a rotating platform was greatest (a) for highly lateralized tamarins, (b) when the preferred hands were used for reaching, (c) for young tamarins, and (d) when the tamarins stood on a narrow, unstable platform instead of a wide, stable one. The results suggest that evolution of species-level handedness is dependent on prior natural selection for increased manual performance that accompanies strongly lateralized hand preferences.

Continuous measurement of systemic vascular resistance.

We have successfully linked a standard patient monitor system (Hewlett Packard M1166A-A66) with the Baxter Edwards Critical-Care Swan Ganz Intellicath continuous cardiac output catheter and the Vigilance continuous cardiac output monitor system to produce continuous values of systemic vascular resistance. Six cases are presented in which marked changes in indexed systemic vascular resistance were observed as a result of clinical interventions. The continuous derivation of systemic vascular resistance has much potential as a diagnostic and research tool as well as allowing rapid accurate assessment of the response of patients to therapy.

Postural effects on manual reaching laterality in squirrel monkeys (Saimiri sciureus) and cotton-top tamarins (Saguinus oedipus).

Squirrel monkeys (Saimiri sciureus) and cotton-top tamarins (Saguinus oedipus) made unimanual food reaches from either a horizontal, quadrupedal posture or a vertical, clinging posture. No population-level handedness occurred in either species. However, in both species, directional lateral preferences weakly expressed for reaching from the stable quadrupedal posture were intensified in the vertical cling posture. This phenomenon, which we designate as soft handedness, may have been an evolutionary precursor to population-level handedness. Right or left turning by the squirrel monkeys before reaching closely predicted use of the right or left hand. However, the magnitude of the association decreased in the more highly lateralized vertical cling condition. This result suggests that as lateral hand preference increases, hand use may become increasingly independent of constraints from prior behavioral and environmental influences.

Dental epidemiology of military operations.

In this paper we review studies that have been conducted on the epidemiology of oral, dental, and maxillofacial conditions during military deployments. The limitations of our current knowledge base are discussed, as is a proposed research effort to enhance the responsiveness of dental support in theaters of operation.