Nathan Hardy

BACKGROUND: Genetic defects in telomere maintenance and repair cause bone marrow failure, liver cirrhosis, and pulmonary fibrosis, and they increase susceptibility to cancer. Historically, androgens have been useful as treatment for marrow failure syndromes. In tissue culture and animal models, sex hormones regulate expression of the telomerase gene. METHODS: In a phase 1-2 prospective study involving patients with telomere diseases, we administered the synthetic sex hormone danazol orally at a dose of 800 mg per day for a total of 24 months. The goal of treatment was the attenuation of accelerated telomere attrition, and the primary efficacy end point was a 20% reduction in the annual rate of telomere attrition measured at 24 months. The occurrence of toxic effects of treatment was the primary safety end point. Hematologic response to treatment at various time points was the secondary efficacy end point. RESULTS: After 27 patients were enrolled, the study was halted early, because telomere attrition was reduced in all 12 patients who could be evaluated for the primary end point; in the intention-to-treat analysis, 12 of 27 patients (44%; 95% confidence interval [CI], 26 to 64) met the primary efficacy end point. Unexpectedly, almost all the patients (11 of 12, 92%) had a gain in telomere length at 24 months as compared with baseline (mean increase, 386 bp [95% CI, 178 to 593]); in exploratory analyses, similar increases were observed at 6 months (16 of 21 patients; mean increase, 175 bp [95% CI, 79 to 271]) and 12 months (16 of 18 patients; mean increase, 360 bp [95% CI, 209 to 512]). Hematologic responses occurred in 19 of 24 patients (79%) who could be evaluated at 3 months and in 10 of 12 patients (83%) who could be evaluated at 24 months. Known adverse effects of danazol--elevated liver-enzyme levels and muscle cramps--of grade 2 or less occurred in 41% and 33% of the patients, respectively. CONCLUSIONS: In our study, treatment with danazol led to telomere elongation in patients with telomere diseases. (Funded by the National Institutes of Health; ClinicalTrials.gov number, NCT01441037.).

Staphylococcus aureus is the most common and most important pathogen following knee and hip arthroplasty procedures. Understanding the epidemiology of invasive S. aureus infections is important to quantify this serious complication. This nested retrospective cohort analysis included adult patients who had undergone insertion of knee or hip prostheses with clean or clean-contaminated wound class at 11 hospitals between 2003–2006. Invasive S. aureus infections, non-superficial incisional surgical site infections (SSIs) and blood stream infections (BSIs), were prospectively identified following each procedure. Prevalence rates, per 100 procedures, were estimated. 13,719 prosthetic knee (62%) and hip (38%) insertion procedures were performed. Of 92 invasive S. aureus infections identified, SSIs were more common (80%) than SSI and BSI (10%) or BSI alone (10%). The rate of invasive S. aureus infection/100 procedures was 0.57 [95% CI: 0.43-0.73] for knee insertion and 0.83 [95% CI: 0.61-1.08] for hip insertion. More than half (53%) were methicillin-resistant. Median time-to-onset of infection was 34 and 26 days for knee and hip insertion, respectively. Infection was associated with higher National Healthcare Safety Network risk index (p ≤ 0.0001). Post-operative invasive S. aureus infections were rare, but difficult-to-treat methicillin-resistant infections were relatively common. Optimizing preventative efforts may greatly reduce the healthcare burden associated with S. aureus infections.

STUDY DESIGN: Therapeutic anti-infective trial in rabbits. OBJECTIVE: The purpose of the present study was to assess the efficacy of intrawound tobramycin powder in terms of eradicating a known bacterial contamination in an Escherichia coli-infected rabbit spinal implantation model. SUMMARY OF BACKGROUND DATA: Implant-associated surgical site infections (SSIs) remain a dreaded complication of spinal surgery. Currently, >30% of all spine SSIs are secondary to gram-negative bacteria. METHODS: Twenty healthy New Zealand white female rabbits underwent simulated partial laminectomies and implantation of a 10-mm titanium wire at L5-L6. All surgical sites were inoculated with 100 μL of tobramycin-sensitive E coli (EC ATCC 25922, 1 × 10 colony-forming units [CFU]/mL). Before closure, tobramycin powder (120 mg) was placed into the wound of 10 rabbits. All rabbits were sacrificed on postoperative day 4. Tissue and wire samples were explanted for bacteriologic analysis. A Fisher exact test was used to assess differences in categorical variables and an independent samples t test was used to assess mean group differences. RESULTS: The experimental and control rabbits were similar in weight (mean ± standard deviation, 3.22 ± 0.12 kg and 3.22 ± 0.14 kg, respectively, P = 1.0), sex distribution, and duration of surgery (13.1 ± 2.4 minutes and 11.6 ± 2.1 minutes, P = 0.39). Bacterial cultures of the tissue samples were negative for all 10 tobramycin-treated rabbits and positive for all 10 control rabbits (P < 0.0001). Bacterial growth occurred in 39 of 40 samples from control rabbits, but zero of the 40 samples from the tobramycin group (P < 0.0001). Blood culture samples from all rabbits were negative for bacterial growth. No rabbit had evidence of sepsis or tobramycin toxicity. CONCLUSION: In a rabbit spine-infection model, intrawound tobramycin eliminated E coli surgical site contamination. All rabbits without intrawound tobramycin had persistent E coli contamination. LEVEL OF EVIDENCE: N /A.

Abstract Abnormal telomere lengths have been linked to cancer and other hematologic disorders. Determination of mean telomere content (MTC) is traditionally performed by Southern blotting and densitometry, giving a mean telomere restriction fragment (TRF) value for the total cell population studied. Here, we compared a quantitative Polymerase Chain Reaction approach (qPCR) and a flow cytometric approach, fluorescence in situ hybridization (Flow‐FISH), to evaluate telomere content distribution in total patient peripheral blood mononuclear cells or specific cell populations. Flow‐FISH is based on in situ hybridization using a fluorescein‐labeled peptide nucleic acid (PNA) (CCCTAA) 3 probe and DNA staining with propidium iodide. We showed that both qPCR and Flow‐FISH provide a robust measurement, with Flow‐FISH measuring a relative content longer than qPCR at a single cell approach and that TRF2 fluorescence intensity did not correlate with MTC. Both methods showed comparable telomere content reduction with age, and the rate of relative telomere loss was similar. Published 2016 Wiley Periodicals Inc. This article is a US government work and, as such, is in the public domain in the United States of America.

STUDY DESIGN: A randomized complete block animal spinal implant infection model with internal control. OBJECTIVE: The aim of this study was to develop a spinal implant animal infection model to simulate postoperative gram-negative wound infection. SUMMARY OF BACKGROUND DATA: Implant-associated surgical site infections (SSIs) remain a dreaded complication of spinal surgery. Currently, over 30% of all spine SSIs are secondary to gram-negative bacteria. Traditional animal models have utilized gram-positive inoculums to simulate postoperative infection, but there exists no model in the literature for gram-negative infection in the setting of spinal instrumentation. METHODS: Five New Zealand white female rabbits underwent simulated partial laminectomies and implantation of a 5 mm titanium wire adjacent to the spinous processes of vertebra T4, T9, L1, and L6 to mimic posterior spinal instrumentation. The second site, T9, was used as the sterile internal control sites, while all other sites were challenged with varying inoculums of Escherichia coli (EC American Type Culture Collection 25922): 10, 10, 10, 10, and 10 Colony Forming Units (CFU). The rabbits were sacrificed 4 days postoperatively and bacterial loads were assayed from the implants and surrounding tissue. RESULTS: No evidence for infection was observed in any of the sterile control sites. The lowest inoculum of E. coli (10 CFU) did not produce a reliable infection. Inoculation with 10 CFU created a consistent soft tissue infection, but inconsistent infection on implants. Inoculation with 10 CFU was required to consistently produce both soft tissue and implant infection. CONCLUSION: Consistent soft tissue and implant infection was produced with inoculation of 10 CFU of E. coli. Gram-negative infections represent greater than 30% of all spinal SSIs, and this animal model can reliably reproduce such infections with spinal instrumentation that can guide future development of anti-infective therapies. LEVEL OF EVIDENCE: 2.