Feasibility and potential role of ferumoxytol-enhanced neuroimaging in HIV-associated neurocognitive disorder

We assessed ferumoxytol-enhanced brain MRI to identify monocyte/macrophage accumulation in HIV-associated neurocognitive disorder (HAND). Four HIV-infected subjects with undetectable HIV RNA levels on antiretroviral therapy, HIV DNA level in CD14+ cells ≥10 copies/10⁶ cells, and cognitive impairment underwent ferumoxytol-enhanced brain MRI. On post-ferumoxytol susceptibility-weighted images, all HIV-infected subjects demonstrated a diffuse “tram track” appearance in the perivascular regions of cortical and deep white matter vessels suggesting ferumoxytol uptake in monocytes/macrophages. This finding was not present in an HIV-seronegative control. While ferumoxytol may have potential as an imaging biomarker for monocyte/macrophage accumulation in patients with HAND, future study is needed.     

Development of an animal model to investigate optimal laparoscopic trocar site fascial closure

Background

The rate of hernia formation after closure of 10–12 mm laparoscopic trocar sites is grossly under-reported. Using an animal model, we have developed a method to assess trocar site fascial dehiscence and the strength of different methods of fascial closure.

Materials and methods

Pigs (n = 9; 17 ± 2.5 lbs) underwent placement of 12 mm Hasson trocars with pneumoperitoneum maintained for 1 h. Three closure techniques (Figure-of-eight; simple interrupted; pulley) were compared with no fascial closure and to native fascia at five randomly allocated abdominal wall midline locations. Necropsy was performed on the fourth postoperative d. Statistical comparisons of tensile strength and breaking strength based on closure type and trocar location were made using ANOVA with Tukey’s tests.

Results

The mean (SD) force (Newtons) required for fascial disruption varied significantly with closure type [Native Fascia 170 (39), Figure-of-eight 169 (31), Pulley 167 (59), Simple Interrupted 151 (27), No Closure 108 (28)]; P = 0.007. The mean force required for fascial disruption was significantly increased for Native Fascia, Figure-of-eight, and Pulley relative to No Closure (P = 0.013, P = 0.015, P = 0.023, respectively). The mean (SD) force (in Newtons) required for fascial disruption also varied significantly with location of trocar [subxiphoid 181 (43), supraumbilical 151 (23), Umbilical 146 (23), infraumbilical 168 (62), suprapubic 120 (38)]; P = 0.03. The mean force for subxiphoid location was significantly increased relative to the suprapubic location (P = 0.021).

Conclusions

We have developed a novel assessment model that reliably detects differences in fascial integrity after laparoscopic trocar placement and closure. This model will allow for further testing of various trocars and closure techniques, and facilitate hernia prevention strategies.     

Should waist circumference be replaced by index of central obesity (ICO) in definition of metabolic syndrome?

Waist circumference has been widely used as the parameter of central obesity in defining metabolic syndrome. Global consensus definition of metabolic syndrome has suggested various race- and gender-specific cutoffs of waist circumference for quantifying central obesity. We have earlier proposed that using index of central obesity (ICO), the need for race- and gender-specific cutoffs may be obviated. We propose that waist circumference be supplanted with index of central obesity in all definitions of metabolic syndrome. Using index of central obesity a common cutoff of 0.5 applicable across races and genders might be obtained. Moreover, it will enhance the sensitivity of definition by diagnosing subjects who are shorter than general population. Among 258 male and 242 female diabetic patients, subjects with metabolic syndrome (defined as per gender-specific waist circumference cutoffs), were found to have a common lower range of index of central obesity suggesting that a common cutoff of waist circumference may be obtained. In another study from National Health and Nutrition Examination Survey database, replacing index of central obesity with waist circumference was found to enhance the specificity and sensitivity of definition of metabolic syndrome.