Recent Research Articles from UNTHSC

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Assessment of the role of DNA repair in damaged forensic samples.

Tue, 05/13/2014 - 4:04am

Assessment of the role of DNA repair in damaged forensic samples.

Int J Legal Med. 2014 May 3;

Authors: Ambers A, Turnbough M, Benjamin R, King J, Budowle B

Abstract
Previous studies on DNA damage and repair have involved in vitro laboratory procedures that induce a single type of lesion in naked templates. Although repair of singular, sequestered types of DNA damage has shown some success, forensic and ancient specimens likely contain a number of different types of lesions. This study sought to (1) develop protocols to damage DNA in its native state, (2) generate a pool of candidate samples for repair that more likely emulate authentic forensic samples, and (3) assess the ability of the PreCR(TM) Repair Mix to repair the resultant lesions. Complexed, native DNA is more difficult to damage than naked DNA. Modified procedures included the use of higher concentrations and longer exposure times. Three types of samples, those that demonstrated damage based on short tandem repeat (STR) profile signals, were selected for repair experiments: environmentally damaged bloodstains, bleach-damaged whole blood, and human skeletal remains. Results showed trends of improved performance of STR profiling of bleach-damaged DNA. However, the repair assay did not improve DNA profiles from environmentally damaged bloodstains or bone, and in some cases resulted in lower RFU values for STR alleles. The extensive spectrum of DNA damage and myriad combinations of lesions that can be present in forensic samples appears to pose a challenge for the in vitro PreCR(TM) assay. The data suggest that the use of PreCR in casework should be considered with caution due to the assay's varied results.

PMID: 24792635 [PubMed - as supplied by publisher]

Transient focal cerebral ischemia induces long-term cognitive function deficit in an experimental ischemic stroke model.

Tue, 05/13/2014 - 4:04am
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Transient focal cerebral ischemia induces long-term cognitive function deficit in an experimental ischemic stroke model.

Neurobiol Dis. 2013 Nov;59:18-25

Authors: Li W, Huang R, Shetty RA, Thangthaeng N, Liu R, Chen Z, Sumien N, Rutledge M, Dillon GH, Yuan F, Forster MJ, Simpkins JW, Yang SH

Abstract
Vascular dementia ranks as the second leading cause of dementia in the United States. However, its underlying pathophysiological mechanism is not fully understood and no effective treatment is available. The purpose of the current study was to evaluate long-term cognitive deficits induced by transient middle cerebral artery occlusion (tMCAO) in rats and to investigate the underlying mechanism. Sprague-Dawley rats were subjected to tMCAO or sham surgery. Behavior tests for locomotor activity and cognitive function were conducted at 7 or 30days after stroke. Hippocampal long term potentiation (LTP) and involvement of GABAergic neurotransmission were evaluated at 30days after sham surgery or stroke. Immunohistochemistry and Western blot analyses were conducted to determine the effect of tMCAO on cell signaling in the hippocampus. Transient MCAO induced a progressive deficiency in spatial performance. At 30days after stroke, no neuron loss or synaptic marker change in the hippocampus were observed. LTP in both hippocampi was reduced at 30days after stroke. This LTP impairment was prevented by blocking GABAA receptors. In addition, ERK activity was significantly reduced in both hippocampi. In summary, we identified a progressive decline in spatial learning and memory after ischemic stroke that correlates with suppression of hippocampal LTP, elevation of GABAergic neurotransmission, and inhibition of ERK activation. Our results indicate that the attenuation of GABAergic activity or enhancement of ERK/MAPK activation in the hippocampus might be potential therapeutic approaches to prevent or attenuate cognitive impairment after ischemic stroke.

PMID: 23845275 [PubMed - indexed for MEDLINE]

Comparison of the accuracy of kriging and IDW interpolations in estimating groundwater arsenic concentrations in Texas.

Tue, 05/13/2014 - 4:04am
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Comparison of the accuracy of kriging and IDW interpolations in estimating groundwater arsenic concentrations in Texas.

Environ Res. 2014 Apr;130:59-69

Authors: Gong G, Mattevada S, O'Bryant SE

Abstract
Exposure to arsenic causes many diseases. Most Americans in rural areas use groundwater for drinking, which may contain arsenic above the currently allowable level, 10µg/L. It is cost-effective to estimate groundwater arsenic levels based on data from wells with known arsenic concentrations. We compared the accuracy of several commonly used interpolation methods in estimating arsenic concentrations in >8000 wells in Texas by the leave-one-out-cross-validation technique. Correlation coefficient between measured and estimated arsenic levels was greater with inverse distance weighted (IDW) than kriging Gaussian, kriging spherical or cokriging interpolations when analyzing data from wells in the entire Texas (p<0.0001). Correlation coefficient was significantly lower with cokriging than any other methods (p<0.006) for wells in Texas, east Texas or the Edwards aquifer. Correlation coefficient was significantly greater for wells in southwestern Texas Panhandle than in east Texas, and was higher for wells in Ogallala aquifer than in Edwards aquifer (p<0.0001) regardless of interpolation methods. In regression analysis, the best models are when well depth and/or elevation were entered into the model as covariates regardless of area/aquifer or interpolation methods, and models with IDW are better than kriging in any area/aquifer. In conclusion, the accuracy in estimating groundwater arsenic level depends on both interpolation methods and wells' geographic distributions and characteristics in Texas. Taking well depth and elevation into regression analysis as covariates significantly increases the accuracy in estimating groundwater arsenic level in Texas with IDW in particular.

PMID: 24559533 [PubMed - indexed for MEDLINE]

Dual plating of humeral shaft fractures: orthogonal plates biomechanically outperform side-by-side plates.

Tue, 05/06/2014 - 4:04am
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Dual plating of humeral shaft fractures: orthogonal plates biomechanically outperform side-by-side plates.

Clin Orthop Relat Res. 2014 Apr;472(4):1310-7

Authors: Kosmopoulos V, Nana AD

Abstract
BACKGROUND: Single large-fragment plate constructs currently are the norm for internal fixation of middiaphyseal humerus fractures. In cases where humeral size is limited, however, dual small-fragment locking plate constructs may serve as an alternative. The mechanical effects of different possible plate configurations around the humeral diaphysis may be important, but to our knowledge, have yet to be investigated.
QUESTIONS/PURPOSES: We used finite element analysis to compare the simulated mechanical performance of five different dual small-fragment locking plate construct configurations for humeral middiaphyseal fracture fixation in terms of (1) stiffness, (2) stress shielding of bone, (3) hardware stresses, and (4) interfragmentary strain.
METHODS: Middiaphyseal humeral fracture fixation was simulated using the finite element method. Three 90° and two side-by-side seven-hole and nine-hole small-fragment dual locking plate configurations were tested in compression, torsion, and combined loading. The configurations chosen are based on implantation using either a posterior or anterolateral approach.
RESULTS: All three of the 90° configurations were more effective in restoring the intact compressive and torsional stiffness as compared with the side-by-side configurations, resulted in less stress shielding and stressed hardware, and showed interfragmentary strains between 5% to 10% in torsion and combined loading.
CONCLUSIONS: The nine-hole plate anterior and seven-hole plate lateral (90° apart) configuration provided the best fixation. Our findings show the mechanical importance of plate placement with relation to loading in dual-plate fracture-fixation constructs.
CLINICAL RELEVANCE: The results presented provide novel biomechanical information for the orthopaedic surgeon considering different treatment options for middiaphyseal humeral fractures.

PMID: 24218163 [PubMed - indexed for MEDLINE]

Thoracic and abdominal lymphatic pump techniques inhibit the growth of S. pneumoniae bacteria in the lungs of rats.

Tue, 05/06/2014 - 4:04am
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Thoracic and abdominal lymphatic pump techniques inhibit the growth of S. pneumoniae bacteria in the lungs of rats.

Lymphat Res Biol. 2013 Sep;11(3):183-6

Authors: Creasy C, Schander A, Orlowski A, Hodge LM

Abstract
BACKGROUND: Osteopathic physicians utilize manual medicine techniques called lymphatic pump techniques (LPT) to improve lymphatic flow and enhance immunity. Clinical studies report that LPT enhances antibody responses to bacterial vaccines, shortens duration of cough in patients with respiratory disease, and shortens the duration of intravenous antibiotic therapy and hospital stay in patients with pneumonia. The purpose of this study was to identify if thoracic LPT (Th-LPT) or abdominal LPT (Ab-LPT) would reduce Streptococcus pneumoniae colony-forming units (CFU) in the lungs of rats with acute pneumonia.
METHODS AND RESULTS: Rats were nasally infected with S. pneumoniae and received either control, sham, Ab-LPT, or Th-LPT once daily for 3 consecutive days. On day 4 post-infection, lungs were removed and bacteria were enumerated. Three daily applications of either Ab-LPT or Th-LPT were able to significantly (p<0.05) reduce the numbers of pulmonary bacteria compared to control and sham. There were no significant differences in the percentage or concentration of leukocytes in blood between groups, suggesting neither Ab-LPT nor Th-LPT release leukocytes into blood circulation.
CONCLUSIONS: Our data demonstrate that LPT may protect against pneumonia by inhibiting bacterial growth in the lung; however, the mechanism of protection is unclear. Once these mechanisms are understood, LPT can be optimally applied to patients with pneumonia, which may substantially reduce morbidity, mortality, and frequency of hospitalization.

PMID: 24024572 [PubMed - indexed for MEDLINE]

Assessment and management of back pain.

Tue, 05/06/2014 - 4:04am
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Assessment and management of back pain.

JAMA Intern Med. 2014 Mar;174(3):478-9

Authors: Licciardone JC, Gatchel R, Dagenais S

PMID: 24590092 [PubMed - indexed for MEDLINE]