Sexually dimorphic and developmentally regulated expression of tubulin-specific chaperone protein A in the LMAN of zebra finches

Sex differences in brain and behavior exist across vertebrates, but the molecular factors regulating their development are largely unknown. Songbirds exhibit substantial sexual dimorphisms. In zebra finches, only males sing, and the brain areas regulating song learning and production are much larger in males. Recent data suggest that sex chromosome genes (males ZZ; females ZW) may play roles in sexual differentiation. The present studies tested the hypothesis that a Z-gene, tubulin-specific chaperone protein A (TBCA), contributes to sexual differentiation of the song system. This taxonomically conserved gene is integral to microtubule synthesis, and within the song system, its mRNA is specifically increased in males compared to females in the lateral magnocellular nucleus of the anterior nidopallium (LMAN), a region critical for song learning and plasticity. Using in situ hybridization, Western blot analysis, and immunohistochemistry, we observed effects of both age and sex on TBCA mRNA and protein expression. The transcript is increased in males compared to females at three juvenile ages, but not in adults. TBCA protein, both the number of immunoreactive cells and relative concentration in LMAN, is diminished in adults compared to juveniles. The latter was also increased in males compared to females at post-hatching day 25. With double-label immunofluorescence and retrograde tract tracing, we also document that the majority of TBCA+ cells in LMAN are neurons, and that they include robust nucleus of the arcopallium-projecting cells. These results indicate that TBCA is both temporally and spatially primed to facilitate the development of a sexually dimorphic neural pathway critical for song.

Expression of aromatase and two isozymes of 5α-reductase in the developing green anole forebrain

Neural steroids, as well as the enzymes that produce these hormones, are important for sexual differentiation of the brain during development. Aromatase converts testosterone into oestradiol. 5α-reductase converts testosterone to 5α-dihydrotestosterone and occurs in two isozymes: type 1 (5αR1) and type 2 (5αR2). Each of these enzymes is present in the developing brain in many species, although no work has been carried out examining the expression of all three enzymes in non-avian reptiles with genetic sex determination. In the present study, we evaluated mRNA expression of neural aromatase, 5αR1 and 5αR2, on the day of hatching and at day 50 in one such lizard, the green anole. We describe the distribution of these enzymes throughout the brain and the quantification of mRNA expression in three regions that control adult sexual behaviours: the preoptic area (POA) and ventromedial amygdala (AMY), which are involved in male displays, as well as the ventromedial hypothalamus, which regulates female receptivity. Younger animals had a greater number (POA) and density (AMY) of 5αR1 mRNA expressing cells. We detected no effects of sex or age on aromatase or 5αR2. In comparison with data from adults, the present results support the idea that the green anole forebrain has not completely differentiated by 50 days after hatching and that 5αR1 may play a role in the early development of regions important for masculine function.

Developmental changes in the sexually dimorphic expression of secretory carrier membrane protein 1 and its co-localisation with androgen receptor protein in the zebra finch song system

The song system of zebra finches differs dramatically between the sexes in terms of both structure and function. Only males sing and the brain regions regulating the learning and production of this behaviour are far more developed in males than females. Mechanisms regulating sexual differentiation likely include both direct genetic and hormonal processes. Expression of both mRNA and the protein product for secretory carrier membrane protein 1 (SCAMP1), a sex chromosome gene, are increased in the brains of juvenile males compared to females. Here we investigated developmental changes in SCAMP1 containing cells in song nuclei and co-localisation with androgen receptor (AR) protein from post-hatching day 25 through adulthood. Almost all SCAMP1 cells co-expressed AR and approximately half of the AR cells expressed SCAMP1 in the HVC and robust nucleus in the arcopallium (RA) of both sexes and in the Area X of males (which could not be clearly defined in females). In HVC and RA, more single and double-labelled cells were detected in males than females overall, and the sex differences increased as animals matured. The results suggest the potential for interaction of these two proteins in regulating development of brain and/or behaviour.

Aromatase mRNA in the brain of adult green anole lizards: effects of sex and season

Neural testosterone metabolism, particularly the synthesis of oestradiol (E(2)) via the aromatase enzyme, is important for sexual behaviours in many vertebrates. In green anole lizards, E(2) metabolised from testosterone facilitates female receptivity and increases sexual motivation in males. Testosterone treatment increases aromatase activity in the whole brain homogenates of gonadectomised male, but not female, anoles, which is an effect limited to the breeding season (BS). To investigate the potential for local effects of this enzyme in reproductive behaviour, we used in situ hybridisation for aromatase mRNA to examine expression during the BS and nonbreeding season (NBS) in areas of the brain that control male sexual behaviours [preoptic area (POA) and amygdala (AMY)], as well as one regulating female reproductive behaviours ventromedial hypothalamus (VMH). Males had a greater total number of aromatase-expressing cells in the POA than females, and the density of aromatase-expressing cells (number per unit volume) was greater in the VMH and AMY of females. This density was also higher during the BS than NBS in the POA. Expression of aromatase in the AMY appeared to be lateralised because trends were detected for the left side to have more total cells and more cells per unit volume than the right. These results suggest that, similar to other vertebrates, regional aromatisation of testosterone may be important for the control of sex-specific reproductive behaviours.

Sex- and age-related differences in ribosomal proteins L17 and L37, as well as androgen receptor protein, in the song control system of zebra finches

The zebra finch song system is sexually dimorphic--only males sing, and the morphology of forebrain regions controlling the learning and production of this song is greatly enhanced in males compared to females. Masculinization appears to involve effects of steroid hormones as well as other factors, perhaps including the expression of sex chromosome genes (males: ZZ, females: ZW). The present study investigated three proteins--two encoded by Z-linked genes, ribosomal proteins L17 and L37 (RPL17 and RPL37), including their co-localization with androgen receptor (AR), from post-hatching day 25 to adulthood. Extensive co-expression of AR with the ribosomal proteins was detected in the three song nuclei investigated (HVC, robust nucleus of the arcopallium (RA), and Area X) across these ages. In general, more cells expressed each of these proteins in males compared to females, and the sex differences increased as animals matured. Specific patterns differed across regions and between RPL17 and RPL37, which suggest potential roles of one or both of these proteins in the incorporation and/or differentiation of song system cells.

Conducting oral examinations for cancer in general practice: what are the barriers?

BACKGROUND

The incidence of oral (mouth) cancer in the UK is continuing to rise. Individuals who are at greatest risk rarely visit a dentist but do consult general medical practitioners (GMPs). Therefore, GMPs could have an important role in the early detection of oral cancer. Research has shown that GMPs do not opportunistically screen high-risk individuals; however, the barriers to screening are poorly understood.

OBJECTIVES

To understand the reasons why GMPs may not screen for oral cancer.

METHODS

A questionnaire was developed, using the Theory of Planned Behaviour (TPB), to measure GMPs attitudes to and screening for oral cancer. The questionnaire was designed using all the key theoretical constructs of the TPB and incorporating the themes identified in a qualitative elicitation study. The questionnaire was posted to 499 GPs in Surrey Primary Care trust.

RESULTS

Two hundred and twenty-eight completed questionnaires were returned (46%). Two TPB constructs [subjective norm (e.g. peer pressure) and perceived external control factors (e.g. adequate equipment, time constraints)] were identified as significant predictors of 'intention' to perform oral screening. Intention and perceived internal control factors (e.g. self-efficacy) were predictive of actually performing oral screening with patients.

CONCLUSIONS

The results of the study suggest that there is considerable potential for improving intention to perform oral cancer screening in general practice. Theory-based interventions could include further training to enhance confidence, expertise, knowledge and ease of examination, the provision of adequate equipment in the surgery and increasing the motivation to comply with significant others by introducing guidelines on opportunistic screening.

Pair bonding in the female zebra finch: a potential role for the nucleus taeniae

Male and female zebra finches are highly social and form pair bonds typically associated with reproduction. To determine how these bonds affect a female's behavioral response to future interactions, females were paired with a male for 2 weeks, separated for 48 h, and then exposed to the same or a novel male. Control females were left unpaired and introduced to a novel male. Behaviors, as well as neural ZENK expression, were quantified. Females displayed higher levels of behaviors associated with pair bonds (clumping and preening) toward their mates than novel males, and display of these behaviors was correlated with expression of the immediate early gene ZENK in the nucleus taeniae of one group of females, those interacting with their mates. Behaviors of the stimulus males were largely unaffected, but those interacting with an unpaired female attempted to mount more than those interacting with their mates. The results indicate that the nucleus taeniae may play some role in the maintenance of pair bonds in this species. Additionally, females may provide some signal to influence elements of the behavior of males.

Phase III study of irinotecan/5FU/LV (FOLFIRI) or oxaliplatin/5FU/LV (FOLFOX) ± cetuximab for patients (pts) with untreated metastatic adenocarcinoma of the colon or rectum (MCRC): CALGB 80203 preliminary results

3509

Background: FOLFIRI or FOLFOX are 1st-line treatments (Rx) for MCRC. Cetuximab is an IgG1 Mab that targets the epidermal growth factor receptor (EGFR) and is approved as monotherapy or in combination with irinotecan in irinotecan-refractory, EGFR + pts with MCRC. CALGB 80203 randomized untreated MCRC pts to FOLFOX or FOLFIRI ± cetuximab (independent of EGFR status.) Methods: Pts with performance status 0–1 with tumor blocks available for EGFR analysis received either irinotecan 180 mg/m2 over 1.5 hours (h) or oxaliplatin 85 mg/m2 over 2h combined with LV 400 mg/m2 over 2h and 5FU 400 mg/m2 bolus, then 46–48h CI 5FU 2400 mg/m2 q o w. Cetuximab dose: 400 mg/m2 loading dose, then 250 mg/m2 qw. Rx continued until progression or toxicity; subsequent Rx was not mandated although information was collected on such rx. Accrual goal was 2200 pts with intended 1° endpt of overall survival (OS). 80203 closed administratively in 1/05 (due to slow accrual) with 238 pts accrued. 2° endpts of response rate (RR), progression free survival (PFS), duration of R and toxicity are now able to be analyzed. Results: Accrual: FOLFIRI (A) - 61; FOLFIRI + cetuximab (B) - 59: FOLFOX (C) - 60; FOLFOX + cetuximab (D) - 58; approx median follow-up (f/u) is 12 months. RR (CR + PR, not all yet confirmed): A - 34%; B - 42%; C - 32%; D - 55%. RR was similar in the FOLFIRI or FOLFOX arms (A+B v. C+D; 38% v. 43%, p=0.44; chi-square) while C225 containing arms (B+D) v. non-C225 arms (A+C) had a superior RR (49% v. 33%; p=0.014, chi-square) It is too early to tell if there are differences in PFS, duration of response or OS. No significant differences in gr III diarrhea or any gr IV toxicities were seen. Conclusions: These results suggest that FOLFIRI and FOLFOX are similar in efficacy for pts with untreated MCRC and that adding cetuximab to either in1st-line Rx appears to increase response rates. PFS and duration of response do not appear different at this analysis. Further f/u and an analysis of prospective companion correlative studies may help to further clarify these results.

[Table: see text]

Low oxygen exposure does not cause pulmonary injury in the newborn rat

BACKGROUND

Two recent studies have suggested that low levels of supplemental inspired oxygen may cause lung injury in preterm infants.

AIMS

To assess lung injury of newborn rats exposed to 14 days of low-level variation of oxygen.

STUDY DESIGN

Four groups were compared with 12 animals per group and 4 lung sections per animal. These were, a control group raised in room air and three groups raised in levels of inspired oxygen fluctuating around the following mean values: group Lo (mean FiO(2) 0.179), group N (mean FiO(2) 0.213), and group Hi (mean FiO(2) 0.247). The degree of oxygen variability was identical for each group. Lungs were inflated at 20 cm H(2)O, fixed and stained with H and E and Millers Elastin.

SUBJECTS

Sprague Dawley albino newborn rats.

OUTCOME MEASURES

Random alveolar areas were studied and analysed using imaging software to assess total amount of tissue and elastin, number of secondary septa, and mean linear intercept.

RESULTS

There were no significant differences between the three experimental oxygen groups and the control group in terms of lung/body weight ratio and the measured markers of lung development.

CONCLUSION

We conclude that low-level oxygen supplementation during early lung development does not affect alveolar development in the newborn rat.

Testosterone regulates androgen receptor immunoreactivity in the copulatory, but not courtship, neuromuscular system in adult male green anoles

Androgens regulate the expression of male reproductive behaviour in diverse vertebrate species, often acting on androgen receptors (AR) to induce structural or functional changes in the nervous system and periphery. Male green anoles possess two sexually dimorphic neuromuscular systems, one controlling throat fan (dewlap) extension, which occurs during courtship, and the other mediating copulatory organ function. Although androgens are required for behavioural activation in both systems, testosterone has differential effects on the neuromuscular morphology. It increases the size of copulatory muscle fibres during the breeding season, but significant effects on dewlap muscle fibre size and motoneurone soma size in either system have not been detected. Corresponding to the lack of testosterone-induced morphological effects in the courtship system, relatively low levels of AR are expressed in the associated motoneurones. The present experiment had two goals, aiming to determine whether: (i) the other courtship and copulatory neuromuscular tissues express AR and (ii) testosterone and/or seasonal environmental changes regulate AR expression. The percentage of AR+ nuclei was evaluated in both the breeding and nonbreeding seasons in gonadally intact adult males (Experiment 1) and in castrated males treated with either testosterone or vehicle (Experiment 2). AR was extensively expressed in the dewlap and copulatory muscles, and in a high percentage of the copulatory motoneurones, but immunoreactivity did not vary across season. Testosterone increased the percentage of AR+ nuclei in the copulatory muscles of both breeding and nonbreeding males but not in the dewlap muscle or copulatory motoneurones. Finally, the target structures for both systems (cartilages and hemipenes) expressed AR in all animals. Therefore, the effects of testosterone on AR immunoreactivity suggest that up-regulation of the receptors may be important for morphological change. However, because all structures investigated in the present experiment expressed AR, the data also indicate that the receptors are involved with other functions.