Human Endogenous Retroviruses: Our Genomic Fossils and Companions

Approximately 8% of the human genome, over four-times more than its protein-coding regions, comprises sequences of viral origin that are known as human endogenous retroviral elements (HERVs). Present in the genome of all human cells, HERVs resulted from the integration of now-extinct exogenous retroviruses into mammalian ancestor germ cells or their precursors on several occasions, sometimes as long as tens of millions of years ago. Most HERVs have become silenced because of mutations such as substitutions, insertions, or deletions, and as a result of epigenetic changes, and are vertically transmitted in the population. Considered for a long time to be part of the "junk DNA", HERVs were shown, in more recent years, to perform critical functions in the host. Two of the very few HERVs known to encode functional proteins, syncytin-1 and syncytin-2, are critical during embryogenesis, when they contribute to the formation of the placenta and facilitate tolerance of the maternal immune system towards the developing fetus. Homologs of syncytin-encoding genes were described in several other species, and it appears that during evolution they were stably endogenized into the respective genomes on multiple occasions and became co-opted for critical physiological functions. The aberrant expression of HERVs has been linked to conditions that include infectious, autoimmune, malignant, and neurological diseases. HERVs, our genomic fossils and storytellers, provide a fascinating and somewhat mysterious insight into our co-evolution with viruses, and will undoubtedly offer many teachings, surprises, and paradigm changes for years to come.

Does Smoking Status Influence Health-Related Quality of Life Outcome Measures in Patients Undergoing ACDF?

STUDY DESIGN

Retrospective comparative study.

OBJECTIVE

Whereas smoking has been shown to affect the fusion rates for patients undergoing an anterior cervical discectomy and fusion (ACDF), the relationship between smoking and health-related quality of life outcome measurements after an ACDF is less clear. The purpose of this study was to evaluate whether smoking negatively affects patient outcomes after an ACDF for cervical degenerative pathology.

METHODS

Patients with tumor, trauma, infection, and previous cervical spine surgery and those with less than a year of follow-up were excluded. Smoking status was assessed by self-reported smoking history. Patient outcomes, including Neck Disability Index, Short Form 12 Mental Component Score, Short Form 12 Physical Component Score (PCS-12), Visual Analogue Scale (VAS) arm pain, VAS neck pain, and pseudarthrosis rates were evaluated. Outcomes were compared between smoking groups using multiple linear and logistic regression, controlling for age, sex, and body mass index (BMI), among other factors. A P value <.05 was considered significant.

RESULTS

A total of 264 patients were included, with a mean follow-up of 19.8 months, age of 53.1 years, and BMI of 29.6 kg/m2. There were 43 current, 69 former, and 152 nonsmokers in the cohort. At baseline, nonsmokers had higher PCS-12 scores than current smokers (P = .010), lower VAS neck pain than current (P = .035) and former (P = .014) smokers, as well as lower VAS arm pain than former smokers (P = .006). Postoperatively, nonsmokers had higher PCS-12 scores than both current (P = .030) and former smokers (P = .035). Smoking status was not a significant predictor of change in patient outcome in multivariate analysis.

CONCLUSIONS

Whereas nonsmokers had higher function and lower pain than former or current smokers preoperatively, smoking status overall was not found to be an independent predictor of outcome scores after ACDF. This supports the notion that smoking status alone should not deter patients from undergoing ACDF for cervical degenerative pathology.

Risk of adverse swallowing events and choking during deworming for preschool-aged children

BACKGROUND

In areas where the prevalence of soil-transmitted helminthiasis (STH) is >20%, the World Health Organization (WHO) recommends that deworming medication be given periodically to preschool-age children. To reduce risk of choking-related deaths in children <3 years old, WHO recommends that deworming tablets be crushed and given with water. Little is known about how widely this is practiced or its effectiveness.

METHODOLOGY AND PRINCIPAL FINDINGS

Albendazole distributions for STH were observed for children 1-4 years old in 65 sites in India and Haiti. Information was recorded on child demographics; child demeanor immediately before, as well as struggling or resistance during albendazole administration; tablet form (i.e., crushed or not); and adverse swallowing events (ASEs), including choking, spitting; coughing; gagging; vomiting; and expelling a crushed tablet in a "cloud" of powder. Of 1677 children observed, 248 (14.8%) had one or more ASEs. ASE risk was 3.6% with whole tablets, 25.4% with crushed tablets, and 34.6% when crushed tablets were mixed with water. In multivariate analysis, ASE risk was significantly associated with children 1 year (OR 2.7) or 2 years (OR 2.9) of age; male gender (OR 1.6); non-content child demeanor (fearful, fussy, or combative) before albendazole administration (OR 4.3); child struggling when given albendazole (OR 2.1); and giving water, either after the tablet or mixed with it (OR 5.8). Eighteen (1.1%) children choked, none fatally; 17 choking incidents occurred with crushed tablets. In a multivariate analysis that controlled for distribution site, the only significant risk factor for choking was non-content demeanor (OR 20.6).

CONCLUSIONS AND SIGNIFICANCE

Deworming-related choking deaths in young children are preventable. In our sample, risk of choking could have been reduced by 79.5% if deworming tablets were not given to young children who were fussy, fearful, or combative or who struggled to resist tablet administration, with only an 18.4% reduction in drug coverage.