Diagnostic contribution of individual components of adrenal function tests to diagnose canine hyperadrenocorticism.

There is limited information regarding the value of constitutive components of the ACTH stimulation test (ACTHST) and low-dose dexamethasone suppression test (LDDST) including serum baseline cortisol (BC), difference between post-ACTH stimulation cortisol (PC) and BC (ΔACTHC), cortisol concentration 4h after dexamethasone administration (4HC), difference between 4HC and BC (Δ4C), and the difference between cortisol concentration 8h after dexamethasone administration and 4HC (Δ8C). Therefore, the objective of this study was to determine if these components can predict hyperadrenocorticism, pituitary-dependent hyperadrenocorticism (PDH), or functional adrenocortical tumor (FAT) in dogs. Cortisol concentrations were normalized, as fold change (FC), to the PC reference interval upper limit. A total of 1267 dogs were included, with hyperadrenocorticism diagnosed in 537 (PDH, n=356; FAT, n=28; undetermined, n=153) and excluded in 730. The area under the receiver operating curves for BC, ΔACTHC, 4HC, Δ4C, and Δ8C to predict hyperadrenocorticism were 0.76 (95% confidence interval (CI), 0.73-0.79), 0.91 (95% CI, 0.89-0.93), 0.83 (95% CI, 0.80-0.87), 0.55 (95% CI, 0.50-0.60), and 0.67 (95% CI, 0.62-0.72), respectively. A diagnostic limit of ≥0.78 FC for ΔACTHC had excellent sensitivity (1.00; 95% CI, 0.74-1.00), but poor specificity (0.67; 95% CI, 0.64-0.71), to predict FAT in dogs with a positive ACTHST. A diagnostic limit of ≥-0.26 FC for Δ4C had excellent sensitivity (1.00; 95% CI, 0.79-1.00), but poor specificity (0.21; 95% CI, 0.18-0.26), to predict FAT in dogs with a positive LDDST. In hyperadrenocorticoid dogs that have positive ACTHST or LDDST results, ΔACTHC or Δ4C, respectively, could be used to exclude FAT.

The effect of aging on the shape of the proximal femur.

The design of cementless femoral prostheses is based on the assumption that age and gender do not affect the shape of the proximal femur. To test this hypothesis, standard anteroposterior and lateral radiographs were prepared of 4 sets of 20 femora, obtained from young (range, 40-60 years) and elderly (range, 60-90 years) donors of both genders. The intracortical and extracortical borders of each femur were digitized electronically, and key parameters were measured to define the shape and dimensions of the medullary canal and the position of the femoral head. Systematic differences were observed between the size and shape of male and female femora. Extracortical dimensions were larger in the male femora by 14% to 19%, and endosteal dimensions by 11% to 24%. However, there were no significant differences between the canal shape of young male and young female femora in the coronal, sagittal, or transverse planes. The male femora displayed no significant differences in canal shape or endosteal width as a function of age. Profound differences were observed in the endosteal shape and diaphyseal dimensions of the young and old female femora. The older female femora had wider canals at the level of the isthmus, with a significant reduction in the canal flare index (the ratio between the canal width proximal to the lesser trochanter and at the isthmus). This study demonstrates that cementless femoral prostheses of 1 standard shape cannot provide a close fit to the endosteal contours of young and elderly women.

The adequacy of cytology and colposcopy in diagnosing cervical neoplasia in HIV-seropositive women.

The purpose of this study was to compare cytology and colposcopy as predictors of cervical intraepithelial neoplasia (CIN) in women infected with the human immunodeficiency virus (HIV). A cross-sectional analysis of cytology, colposcopy, and colposcopic biopsy results from 51 HIV-seropositive women attending an ambulatory HIV service was conducted. Cytology slides were reviewed by two cytopathologists blinded to patients' HIV status. There was strong agreement in the readings of two cytopathologists, with a kappa score of 0.9. Of 29 women with normal cytology, 21 (72%) had pathology on histology, including 7 (24%) with CIN. Colposcopic impression correlated well with histology results. Of 22 women with abnormal cytology, 82% had abnormal histology. The overall prevalence of CIN was high at 45%, increasing from 35% in women with CD4 counts over 400 to 56% in women with CD4 counts below 200. In conclusion, screening cytology is limited by false-negative results; routine colposcopy should be considered in this high-risk population.

Tetramesityldisilene, a stable compound containing a silicon-silicon double bond.

Irradiation of 2,2-bis(2,4,6-trimethylphenyl)hexamethyltrisilane in hydrocarbon solution produces tetramesityldisilene, which can be isolated as a yellow-orange solid stable to room temperature and above in the absence of air. Like the olefins of carbon chemistry, tetramesityldisilene undergoes addition reactions across the silicon-silicon double bond.