The spatial relationship between neurons and astrocytes in HIV-associated dementia

Specific neuronal spatial distributional patterns have previously been correlated with increasing severity of HIV-associated dementia (HAD). As astrocytes are also a putative site of neurotoxicity, we investigated the spatial relationships of astrocytes with pyramidal and interneurons in the superior frontal gyrus from 29 patients who died from acquired immunodeficiency syndrome. Frontal cortical brain tissue was taken from diseased HIV patients who had been assessed for the presence and severity of HAD using the Memorial Sloan-Kettering Scale. No correlation was found between neuronal density and severity of dementia. However, the pattern of astrocytes became more clustered as dementia progressed. Bivariate spatial pattern analysis of neuronal populations with astrocytes revealed that, with increasing dementia severity, astrocytes and large pyramidal neurons increasingly “repelled” each other, while astrocytes and interneurons evidenced increasing “attraction.” This implies that astrocytes may be more likely to be situated in the vicinity of surviving interneurons but less likely to be situated near surviving large pyramidal neurons in the setting of progressing HAD.     

Asymptomatic transmission of Treponema pallidum (syphilis) through deceased donor liver transplantation

A 55‐year‐old woman underwent liver transplantation (LT) with a graft from a deceased donor. Mandatory pre‐donation investigations showed positive syphilis serology that was available only after the transplant, with high Treponema pallidum particle agglutination assay titer compatible with donor syphilis infection. Despite the institution of appropriate post‐exposure prophylaxis, the recipient demonstrated latent seroconversion; however, liver graft function improved without evidence of syphilitic hepatitis or other manifestations of the disease. Through this first reported case of asymptomatic transmission of syphilis following LT, we highlight the investigations and treatment strategies for donor‐derived syphilis in liver transplant recipients. This report supplements the existing limited evidence on safe use of infected grafts from syphilitic donors through appropriate post‐exposure prophylaxis.     

Vertebral fractures and trabecular microstructure in men with prostate cancer on androgen deprivation therapy

Androgen deprivation therapy (ADT), a treatment for prostate cancer, is associated with bone loss and fractures. Dual‐energy X‐ray absorptiometry (DXA)–measured bone mineral density does not assess vertebral fractures (VF). High‐resolution micro‐magnetic resonance imaging (HR‐MRI) assesses bone microarchitecture and provides structural information. To determine if VF identification increased the diagnosis of osteoporosis beyond DXA and if HR‐MRI demonstrated skeletal deterioration in men with VF, we cross‐sectionally studied 137 men aged ≥ 60 years with nonmetastatic prostate cancer on ADT for ≥ 6 months. Vertebral fracture assessment (VFA) by DXA was confirmed with X‐rays. HR‐MRI of the wrist included bone volume to total volume (BV/TV), surface density (trabecular plates), surface/curve ratio (plates/rods), and erosion index (higher depicts deterioration). VF were found in 37% of men; the majority were unknown. Seven percent of participants were classified as osteoporotic by hip or spine DXA. Thirty‐seven percent of men without osteoporosis by DXA had VF identified, suggesting that 90% of patients with clinical osteoporosis would have been misclassified by DXA alone. By ANOVA comparison across VF grades, the BV/TV, surface density, and spine, hip, and wrist DXA were lower, and erosion index was higher in men with moderate‐severe VF compared with lesser grades (all p < 0.05). By unadjusted ROC analysis, the addition of HR‐MRI to DXA at the spine, hip, and femoral neck added substantially (AUC increased 0.831 to 0.902, p < 0.05) to prediction of moderate‐severe vertebral fracture. HR‐MRI indices were associated with spine, hip, and wrist DXA measures (p < 0.01). Longer duration of ADT was associated with lower BV/TV, surface density, and surface/curve ratio (p < 0.05). ADT for men with prostate cancer is associated with silent VF. DXA alone leads to misclassifications of osteoporosis, which can be avoided by VF assessment. HR‐MRI provides a novel technique to assess deterioration of structural integrity in men with VF and adds micro‐structural information. © 2013 American Society for Bone and Mineral Research     

Low virulent oral Candida albicans strains isolated from smokers

It is widely accepted that tabagism is a predisposing factor to oral candidosis and cumulate data suggest that cigarette compounds may increase candidal virulence. To verify if enhanced virulence occurs in Candida albicans from chronic smokers, a cohort of 42 non-smokers and other of 58 smokers (all with excellent oral conditions and without signs of candidosis) were swabbed on tong dorsum and jugal mucosa. Results showed that oral candidal loads do not differ between smoker and non-smokers. Activities of secreted aspartyl-protease (Sap), phospholipase, chondroitinase, esterase-lipase, and haemolysin secretions were screened for thirty-two C. albicans isolates. There were detected significant increments in phospholipasic and chondroitinasic activities in isolates from non-smokers. For other virulence factors, no differences between both cohorts were achieved.