HIV testing in an ethnically diverse sample of American university students: associations with violence/abuse and covariates

Associations linking HIV infection to violence and abuse are well documented; however, little is known about how violence/abuse is related to HIV testing behavior, particularly among undergraduate university students, who test at lower rates compared to non-student peers in the United States. We assessed history of HIV testing in an ethnically diverse sample of undergraduates in California (n = 1,210); and examined potential associations between testing and various forms of violence/abuse, while controlling for covariates. Whereas 73.4 % of students were sexually active in the past year, only 26.3 % had ever tested for HIV. At the bivariate level, testing was associated with experiencing verbal abuse and sexual violence/coercion, and perpetrating verbal abuse. Experiencing verbal abuse remained significant in multivariate analysis. We discuss findings in a syndemics framework, considered in combination with social psychology-based health behavior theories. Enhanced HIV testing scale-up initiatives for undergraduates are needed and should consider integration with violence prevention programs.     

Epidural spinal cord stimulation plus quipazine administration enable stepping in complete spinal adult rats

We hypothesized that epidural spinal cord stimulation (ES) and quipazine (a serotonergic agonist) modulates the excitability of flexor and extensor related intraspinal neural networks in qualitatively unique, but complementary, ways to facilitate locomotion in spinal cord-injured rats. To test this hypothesis, we stimulated (40 Hz) the S(1) spinal segment before and after quipazine administration (0.3 mg/kg, ip) in bipedally step-trained and nontrained, adult, complete spinal (mid-thoracic) rats. The stepping pattern of these rats was compared with control rats. At the stimulation levels used, stepping was elicited only when the hindlimbs were placed on a moving treadmill. In nontrained rats, the stepping induced by ES and quipazine administration was non-weight bearing, and the cycle period was shorter than in controls. In contrast, the stepping induced by ES and quipazine in step-trained rats was highly coordinated with clear plantar foot placement and partial weight bearing. The effect of ES and quipazine on EMG burst amplitude and duration was greater in flexor than extensor motor pools. Using fast Fourier transformation analysis of EMG bursts during ES, we observed one dominant peak at 40 Hz in the medial gastrocnemius (ankle extensor), whereas there was less of dominant spectral peak in the tibialis anterior (ankle flexor). We suggest that these frequency distributions reflect amplitude modulation of predominantly monosynaptic potentials in the extensor and predominantly polysynaptic pathways in the flexor muscle. Quipazine potentiated the amplitude of these responses. The data suggest that there are fundamental differences in the circuitry that generates flexion and extension during locomotion.     

Screening for Aortic Aneurysm After Treatment of Coarctation

Isolated coarctation of the aorta (CoA) occurs in 6–8 % of patients with congenital heart disease. After successful relief of obstruction, patients remain at risk for aortic aneurysm formation at the site of the repair. We sought to determine the diagnostic utility of echocardiography compared with advanced arch imaging (AAI) in diagnosing aortic aneurysms in pediatric patients after CoA repair. The Congenital Heart Databases from 1996 and 2009 were reviewed. All patients treated for CoA who had AAI defined by cardiac magnetic resonance imaging (MRI), computed tomography (CT), or catheterization were identified. Data collected included the following: type, timing, and number of interventions, presence and time to aneurysm diagnosis, and mortality. Patients were subdivided into surgical and catheterization groups for analysis. Seven hundred and fifty-nine patients underwent treatment for CoA during the study period. Three hundred and ninety-nine patients had at least one AAI. Aneurysms were diagnosed by AAI in 28 of 399 patients at a mean of 10 ± 8.4 years after treatment. Echocardiography reports were available for 380 of 399 patients with AAI. The sensitivity of echocardiography for detecting aneurysms was 24 %. The prevalence of aneurysms was significantly greater in the catheterization group (p < 0.05) compared with the surgery group. Aneurysm was also diagnosed earlier in the catheterization group compared with the surgery group (p = 0.02). Multivariate analysis showed a significantly increased risk of aneurysm diagnosis in patients in the catheterization subgroup and in patients requiring more than three procedures. Aortic aneurysms continue to be an important complication after CoA repair. Although serial echocardiograms are the test of choice for following-up most congenital cardiac lesions in pediatrics, our data show that echocardiography is inadequate for the detection of aneurysms after CoA repair. Because the time to aneurysm diagnosis was shorter and the risk greater in the catheterization group (particularly for patients requiring more than one procedure), surveillance with cardiac MRI or CT should begin earlier in these patients.     

Voluntary exercise increases neurotrophin-3 and its receptor TrkC in the spinal cord

We have evaluated changes in the expression of neurotrophin-3 (NT-3) and its tyrosine kinase C (TrkC) receptor in the neuromuscular system as a result of voluntary physical activity. We assessed changes in the mRNAs and proteins for NT-3 and TrkC in the lumbar spinal cord and associated soleus muscle following 3 and 7 days of voluntary wheel running. We used quantitative Taqman RT-PCR to measure mRNA and ELISA to assess protein levels. NT-3 mRNA and protein levels increased in the spinal cord to reach statistical significance after 7 days of exercise compared to sedentary control rats. Immunohistochemical analyses localized the elevated NT-3 to the substantia gelatinosa (SG) and nucleus of the dorsal horn. TrkC mRNA levels were significantly elevated in the spinal cord after 3 and 7 days of running. In the soleus muscle, NT-3 mRNA levels and its receptor TrkC were elevated after 3 days, while NT-3 protein levels remained unaffected. The results demonstrate that voluntary exercise has a differential effect on NT-3 as well as its receptor TrkC in the neural and muscular components of the neuromuscular system, and emphasize the role of voluntary activity on the spinal cord and muscle.     

Construction and characterization of an acapsular mutant of Mannheimia haemolytica A1

The nmaA and nmaB genes, which code for UDP-GlcNAc-2-epimerase and UDP-ManNAc-dehydrogenase, respectively, are involved in capsular polysaccharide biosynthesis in Mannheimia haemolytica A1. A chloramphenicol resistance (Cm(r)) cassette cloned behind an M. haemolytica A1 promoter, plpcat, was created and used to interrupt nmaA and nmaB. A 1.3-kbp DNA fragment that encompasses part of nmaA and nmaB was replaced by the 1.0-kbp plpcat, resulting in a knockout mutant which is Cm(r) and unable to synthesize N-acetylmannosamine (ManNAc) and N-acetylmannosaminuronic acid (ManNAcA). The DNA replacement was confirmed by Southern hybridization and PCR analyses of the nmaA and nmaB loci. Electron microscopy examination of the mutant showed the absence of capsular materials compared to the parent strain. The loss of NmaA and NmaB activity was confirmed by analysis of carbohydrate moieties using capillary electrophoresis. Serum sensitivity assays indicated that the acapsular mutant is as resistant as the encapsulated parent to complement-mediated killing by colostrum-deprived calf serum but is more sensitive to killing by immune bovine serum. Analysis of lipopolysaccharide prepared from the acapsular mutant and encapsulated parent confirmed that these strains have long O-polysaccharide chains, possibly conferring resistance to serum-mediated killing.