Utilization of hepatitis B core antibody-positive donor liver grafts

Background

The inclusion of hepatitis B core antibody-positive (HBcAb+) liver donors is a strategy utilized to increase organ availability. This study examined HBcAb+ transplantation practices to identify specific factors influencing outcomes.

Methods

Twenty-five HBcAb+ liver transplants were identified retrospectively among 868 adult transplants performed between 1 January 1997 and 31 December 2009. Twelve (48%) recipients had hepatitis C and five (20%) had hepatitis B. Patient and donor demographics, preoperative morbidity, transplant data and outcomes were examined. Statistical analysis was completed using Student''s t-test or the Kaplan–Meier method. A P-value of <0.05 was considered significant.

Results

There was no difference in age, body mass index or comorbidities between HBcAb+ liver recipients and control subjects. Model for End-stage Liver Disease (MELD) scores of >30 were significantly more frequent in HBcAb+ liver recipients (32% vs. 15%; P = 0.04). All patients received immunoglobulin and longterm antiviral therapy as prophylaxis against graft hepatitis B resurgence. No patients who received HBcAb+ livers developed hepatitis B infection on follow-up. Overall survival at 30 days, 1 year and 5 years in HBcAb+ liver recipients was 92%, 74% and 74%, respectively, compared with 96%, 89% and 76%, respectively, in the control group (P = not significant, log-rank test). All except one of the deaths in the HBcAb+ liver recipient group occurred within 90 days postoperatively and in patients with MELD scores >30.

Conclusions

The practice of transplanting HBcAb+ grafts incurs low risk for infection using current methods of prophylaxis. The highest mortality risk was in the early postoperative period, specifically in patients with very high MELD scores. This probably reflects the practice of using positive serology grafts in emergent situations.     

Clinical profile and response to steroids in post-fever retinitis: a nine-year experience from a referral institute in the rural hinterland of Central India

Purpose

To describe the demographics, clinical features, and treatment outcomes with systemic steroids in eyes presenting with post-fever retinitis (PFR) from Central India.

Methods

Single-center, retrospective analysis of 147 eyes of 98 PFR cases between 2011 and 2019.

Results

Mean age of the study cohort was 33.46?±?12.76 years, with 72 males and 26 females. The mean interval between the onset of fever and the diminution of vision was 21.10?±?13.54 days (range 0–60 days). The number of PFR cases increased over the nine years with 89 cases (90.1%) presenting during winters. Unilateral involvement was seen in 49 cases, while 49 had bilateral involvement. Clinical characteristics included: multifocal retinitis (n?=?122; 61.2%), hemorrhages (n?=?132; 89.8%), disc edema (n?=?57; 38.8%), anterior chamber reaction (n?=?28; 19%), and vitritis (n?=?103; 70.1%). Treatment included intravenous followed by oral steroids in 70 patients and oral steroids exclusively in 23; five patients denied treatment. The visual acuity improved from 1.09?±?0.52 LogMAR to 0.29?±?0.42 LogMAR (p?<?0.05).

Conclusion

There has been an increase in the prevalence of PFR cases over the last decade with clustering during the winters. Multifocal retinitis, retinal hemorrhages, and vitritis were the most common clinical findings in our series. The retinitis resolved with improvement in vision following steroid therapy in all eyes.

     

(iii) Biomechanics of the knee and TKR

The principal aim of a total knee replacement (TKR) is to restore painless movements of the knee joint. Osteoarthritis, along with other pathologies that damage the articular surface of the knee, results in painful limitation of knee movement and alteration of shape and alignment of the joint. Restoration of the functional anatomy of the knee, including alignment, soft tissue balancing and restoration of the joint line, are integral to improving function. Factors that ensure long-term survival of the replaced knee have to be addressed while performing this procedure. Biomechanics of the knee and its restoration are key to improving both function and survival of a total knee replacement. Screw home movement in terminal extension and femoral roll back in flexion are unique to the knee joint. The patella improves extensor function by increasing its lever arm. Implant designs available include femoral components of fixed or multiple radii, high flexion knee replacements, posterior cruciate retaining or substituting designs and fixed or mobile tibial inserts. Computer navigation has been used to achieve accurate bone alignment and soft tissue balancing. Further research on these advances is essential to define their role in improving the results of TKR.     

Temporal complexity and heterogeneity of single-neuron activity in premotor and motor cortex

The relationship between neural activity in motor cortex and movement is highly debated. Although many studies have examined the spatial tuning (e.g., for direction) of cortical responses, less attention has been paid to the temporal properties of individual neuron responses. We developed a novel task, employing two instructed speeds, that allows meaningful averaging of neural responses across reaches with nearly identical velocity profiles. Doing so preserves fine temporal structure and reveals considerable complexity and heterogeneity of response patterns in primary motor and premotor cortex. Tuning for direction was prominent, but the preferred direction was frequently inconstant with respect to time, instructed-speed, and/or reach distance. Response patterns were often temporally complex and multiphasic, and varied with direction and instructed speed in idiosyncratic ways. A wide variety of patterns was observed, and it was not uncommon for a neuron to exhibit a pattern shared by no other neuron in our dataset. Response patterns of individual neurons rarely, if ever, matched those of individual muscles. Indeed, the set of recorded responses spanned a much higher dimensional space than would be expected for a model in which neural responses relate to a moderate number of factors-dynamic, kinematic, or otherwise. Complex responses may provide a basis-set representing many parameters. Alternately, it may be necessary to discard the notion that responses exist to "represent" movement parameters. It has been argued that complex and heterogeneous responses are expected of a recurrent network that produces temporally patterned outputs, and the present results would seem to support this view.     

Reference frames for reach planning in macaque dorsal premotor cortex

When a human or animal reaches out to grasp an object, the brain rapidly computes a pattern of muscular contractions that can acquire the target. This computation involves a reference frame transformation because the target's position is initially available only in a visual reference frame, yet the required control signal is a set of commands to the musculature. One of the core brain areas involved in visually guided reaching is the dorsal aspect of the premotor cortex (PMd). Using chronically implanted electrode arrays in two Rhesus monkeys, we studied the contributions of PMd to the reference frame transformation for reaching. PMd neurons are influenced by the locations of reach targets relative to both the arm and the eyes. Some neurons encode reach goals using limb-centered reference frames, whereas others employ eye-centered reference fames. Some cells encode reach goals in a reference frame best described by the combined position of the eyes and hand. In addition to neurons like these where a reference frame could be identified, PMd also contains cells that are influenced by both the eye- and limb-centered locations of reach goals but for which a distinct reference frame could not be determined. We propose two interpretations for these neurons. First, they may encode reach goals using a reference frame we did not investigate, such as intrinsic reference frames. Second, they may not be adequately characterized by any reference frame.