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.

Interlaboratory variation in scoring dicentric chromosomes in a case of partial-body x-ray exposure: implications for biodosimetry networking and cytogenetic "triage mode" scoring.

The international radiation biodosimetry community has recently been engaged in activities focused on establishing cooperative networks for biodosimetric triage for radiation emergency scenarios involving mass casualties. To this end, there have been several recent publications in the literature regarding the potential for shared scoring in such an accident or incident. We present details from a medical irradiation case where two independently validated laboratories found very different yields of dicentric chromosome aberrations. The potential reasons for this disparity are discussed, and the actual reason is identified as being the partial-body nature of the radiation exposure combined with differing criteria for metaphase selection. In the context of the recent networking activity, this report is intended to highlight the fact that shared scoring may produce inconsistencies and that further validation of the scoring protocols and experimental techniques may be required before the networks are prepared to deal satisfactorily with a radiological or nuclear emergency. Also, the findings presented here clearly demonstrate the limitations of the dicentric assay for estimating radiation doses after partial-body exposures and bring into question the usefulness of rapid "triage mode" scoring in such exposure scenarios.

Quartz crystal microbalance-based measurements of shear-induced senescence in human embryonic kidney cells.

Fluid shear and other mechanical forces play an important role in the normal biophysical, biochemical, and gene regulatory responses of vertebrate tissue that are reflected in the expression of normal cell differentiation, growth, and function. Despite some promising work reported on the application of the quartz crystal microbalance (QCM) to both prokaryote and eukaryote cells over the last decade, QCM has yet to be successfully applied to cells in culture under conditions of flow-induced shear. In this study, high sensitivity QCM in conjunction with fluid modelling was used to monitor the onset of senescence in immortalised human embryonic kidney cells under laminar shear stresses of between 0.04 and 335 dyne/cm(2). The feasibility of this approach as a means of quantification and characterisation of cell physiological response and adhesion are explored and discussed.

Aedes aegypti transducing densovirus pathogenesis and expression in Aedes aegypti and Anopheles gambiae larvae.

Aedes aegypti densovirus (AeDNV) is a small DNA virus that has been developed into an expression and transducing vector for mosquitoes [Afanasiev et al. (1994) Exp Parasitol 79: 322-339; Afanasiev et al. (1999) Virology 257: 62-72; Carlson et al. (2000) Insect Transgenesis: Methods and Applications (Handler, A.M. & James, A.A., eds), pp. 139-159. CRC Press, Boca Raton]. Virions carrying a recombinant genome expressing the GFP gene were used to characterize the pathogenesis of the virus in 255 individual Aedes aegypti larvae. The anal papillae of the larvae were the primary site of infection confirming previous observations (Afanasiev etal., 1999; Allen-Muira et al. (1999) Virology 257: 54-61). GFP expression was observed in most cases to spread from the anal papillae to cells of the fat body, and subsequently to many other tissues including muscle fibers and nerves. Infected anal papillae were also observed to shrink, or melanize and subsequently fall off in a virus dependent manner. Three to four day-old larvae were less susceptible to viral infection and, if infected, were more likely to survive into adulthood, with 14% of them still expressing GFP as adults. Higher salt concentrations of 0.10-0.15 M inhibited viral infection. Anopheles gambiae larvae also showed infection of the anal papillae (17%) but subsequent viral dissemination did not occur. The persistence of the reporter gene expression into adulthood of Aedes aegypti indicates that transduction of mosquito larvae with recombinant AeDNV may be a means of introducing a gene of interest into a mosquito population for transient expression.

Ocular rosacea.

Ocular rosacea was diagnosed in 6.3% of a cornea/external disease referral practice where more than half of the patients referred are for corneal surgery. The most common signs and symptoms are also common to many patients in the general practice of ophthalmology, i.e., foreign body sensation, burning, superficial punctate erosions, chalazia and blepharitis. Less common but dangerous to the vision was corneal thinning, vascularization and infiltrates. Three new associated symptoms were described. These were map dot subepithelial opacities, recurrent erosions and moderately severe foreign body sensation, pain or burning with minimal associated signs. Oral tetracycline 250 mg q.i.d. resulted in improvement in almost all patients from 4 to 17 days after initiation of therapy. Although most of the patients have been able to taper and stop therapy, those with foreign body sensation, burning and pain have had recurrences of their symptoms with all attempts at stopping therapy.

Chalazia and rosacea.

Fifty-seven percent of patients scheduled for excision of chalazia over 19 years of age and 64% of patients over the age of 29 were found to have rosacea. This compares to an incidence in our control group of 12% and 13%, respectively. Rosacea was almost twice as common in patients with recurrent chalazia as in those with only one occurrence.

Ocular rosacea.

Ocular rosacea was diagnosed in 49 patients. The most common signs and symptoms were foreign body sensation, burning, superficial punctate erosions, chalazia, and belpharitis. Less common but dangerous to the vision was corneal thinning, vascularization, and infiltrates. Three new associated symptoms were found. These were mapdot subepithelial opacities, recurrent erosions, and moderately severe foreign body sensation, pain or burning with minimal associated signs. Of the 49 patients, 37 were treated with 250 mg of oral tetracycline four times a day, which resulted in improvement in almost all patients from four to 17 days after initiation of therapy. Most of the patients have been able to taper, or taper and stop therapy without recurrence of their symptoms. Those patients with foreign body sensation, burning, and pain required the most prolonged therapy in order to taper or stop treatment with tetracycline.

Significance of donor age in penetrating keratoplasty.

Because the significance of donor age in penetrating keratoplasty remains controversial, a study was undertaken to analyze the results of keratoplastics performed with older (greater than 70) and younger (less than 55) donor corneas. Thirty-seven eyes which received older donor corneas were divided into 4 diagnostic categories and were compared with 37 eyes having the same diagnosis which received younger donor corneas. The average follow-up for both groups was 24 months. There was no significant difference between the number of clear grafts in each group. It would appear that older donor corneas can withstand the surgical trauma of transplantation and remain clear for a relatively significant period.

The acute manifestations of ocular cicatricial pemphigoid: diagnosis and treatment.

Seven patients with ocular cicatricial pemphigoid displayed acute inflammatory activity that could not be attributed to secondary bacterial infections, trichiasis, or lagophthalmos secondary to symblepharon. This acute inflammatory activity was manifested either as a localized conjunctival mound that was ulcerated and intensely hyperemic or as diffuse and intense conjunctival hyperemia and chemosis. Acute disease activity developed shortly after conjunctival biopsy in three patients and appeared spontaneously in the other four patients. Conjunctival biopsy specmens disclosed a heavy infiltrate of polymorphonuclear leucocytes within and beneath the conjunctival epithelium in addition to the chronic inflammatory cells typically found in this condition. The acute manifestations of ocular cicatricial pemphigoid cause rapid shrinkage and scarring of the conjunctiva. Systemic corticosteroids suppressed the acute disease activity and prevented additional scarring in all five patients treated.

Prevention of vitreous loss in aphakic keratoplasty.

Controlled aspiration of aqueous before excising the recipient cornea resulted in maintenance of an intact vitreous face during aphakic penetrating corneal transplants in eight of 11 eyes. Vitreous corneal contact or subsequent graft opacification has not occurred in the study group during the observation period.

A simple technique for removal of recurring granular dystrophy in corneal grafts.

A 63-year-old man and his 24-year-old son developed recurrences of granular dystrophy in their three corneal grafts within three years after surgery. We regrafted one of the son's corneas. Histologic examination of the corneal button removed during surgery showed an avascular connective tissue layer with the histochemical characteristics of granular dystrophy interposed between the epithelium and Bowman's layer. In the remaining two corneal grafts, we fixed the globe with corneal forceps and removed the opaque dystrophic layer by separating it from the cornea with a spatula. Postoperatively, all three corneal grafts were once more transparent.

A simple device to improve blinking.

A blink beeper was devised to remind patients with incomplete or infrequent blinking to blink completely and at normal intervals; the beeper worked by transmitting an audible tone every ten seconds through an earphone. In three postkeratoplasty patients, this simplistic approach not only resulted in a complete blink at regular intervals, but seemed to condition this response to continue when the blink beeper was taken away; this resulted in healing of large chronic epithelial defects. The blink beeper has also proved valuable in patients with either punctate epithelial erosions or those who wore hard contact lenses unsuccessfully because of infrequent or incomplete blinking.