We examined the temporal profile of apoptosis after fluid percussion-induced traumatic brain injury (TBI) in rats and investigated the potential pathophysiological role of caspase-3-like proteases in this process. DNA fragmentation was observed in samples from injured cortex and hippocampus, but not from contralateral tissue, beginning 4 hr after TBI and continuing for at least 3 d. Double labeling of brain with terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) and an antibody directed to neuronal nuclear protein identified apoptotic neurons with high frequency in both traumatized rat cortex and hippocampus. Cytosolic extracts from injured cortex and hippocampus, but not from contralateral or control tissue, induced internucleosomal DNA fragmentation in isolated nuclei with temporal profiles consistent with those of DNA fragmentation observed in vivo. Caspase-3 mRNA levels, estimated by semiquantitative RT-PCR, were elevated fivefold in ipsilateral cortex and twofold in hippocampus by 24 hr after TBI. Caspase-1 mRNA content also was increased after trauma, but to a lesser extent in cortex. Increased caspase-3-like, but not caspase-1-like, enzymatic activity was found in cytosolic extracts from injured cortex. Intracerebroventricular administration of z-DEVD-fmk-a specific tetrapeptide inhibitor of caspase-3-before and after injury markedly reduced post-traumatic apoptosis, as demonstrated by DNA electrophoresis and TUNEL staining, and significantly improved neurological recovery. Together, these results implicate caspase-3-like proteases in neuronal apoptosis induced by TBI and suggest that the blockade of such caspases can reduce post-traumatic apoptosis and associated neurological dysfunction.

BackgroundClinical dogma is that healthy urine is sterile and the presence of bacteria with an inflammatory response is indicative of urinary tract infection (UTI). Asymptomatic bacteriuria (ABU) represents the state in which bacteria are present but the inflammatory response is negligible. Differentiating ABU from UTI is diagnostically challenging, but critical because overtreatment of ABU can perpetuate antimicrobial resistance while undertreatment of UTI can result in increased morbidity and mortality. In this study, we describe key characteristics of the healthy and ABU urine microbiomes utilizing 16S rRNA gene (16S rDNA) sequencing and metaproteomics, with the future goal of utilizing this information to personalize the treatment of UTI based on key individual characteristics.MethodsA cross-sectional study of 26 healthy controls and 27 healthy subjects at risk for ABU due to spinal cord injury-related neuropathic bladder (NB) was conducted. Of the 27 subjects with NB, 8 voided normally, 8 utilized intermittent catheterization, and 11 utilized indwelling Foley urethral catheterization for bladder drainage. Urine was obtained by clean catch in voiders, or directly from the catheter in subjects utilizing catheters. Urinalysis, urine culture and 16S rDNA sequencing were performed on all samples, with metaproteomic analysis performed on a subsample.ResultsA total of 589454 quality-filtered 16S rDNA sequence reads were processed through a NextGen 16S rDNA analysis pipeline. Urine microbiomes differ by normal bladder function vs. NB, gender, type of bladder catheter utilized, and duration of NB. The top ten bacterial taxa showing the most relative abundance and change among samples were Lactobacillales, Enterobacteriales, Actinomycetales, Bacillales, Clostridiales, Bacteroidales, Burkholderiales, Pseudomonadales, Bifidobacteriales and Coriobacteriales. Metaproteomics confirmed the 16S rDNA results, and functional human protein-pathogen interactions were noted in subjects where host defenses were initiated.ConclusionsCounter to clinical belief, healthy urine is not sterile. The healthy urine microbiome is characterized by a preponderance of Lactobacillales in women and Corynebacterium in men. The presence and duration of NB and method of urinary catheterization alter the healthy urine microbiome. An integrated approach of 16S rDNA sequencing with metaproteomics improves our understanding of healthy urine and facilitates a more personalized approach to prevention and treatment of infection.

Spinal cord injury causes secondary biochemical changes leading to neuronal cell death. To clarify the molecular basis of this delayed injury, we subjected rats to spinal cord injury and identified gene expression patterns by high-density oligonucleotide arrays (8,800 genes studied) at 30 minutes, 4 hours, 24 hours, or 7 days after injury (total of 26 U34A profiles). Detailed analyses were limited to 4,300 genes consistently expressed above background. Temporal clustering showed rapid expression of immediate early genes (30 minutes), followed by genes associated with inflammation, oxidative stress, DNA damage, and cell cycle (4 and 24 hours). Functional clustering showed a novel pattern of cell cycle mRNAs at 4 and 24 hours after trauma. Quantitative reverse transcription polymerase chain reaction verified mRNA changes in this group, which included gadd45a, c-myc, cyclin D1 and cdk4, pcna, cyclin G, Rb, and E2F5. Changes in their protein products were quantified by Western blot, and cell-specific expression was determined by immunocytochemistry. Cell cycle proteins showed an increased expression 24 hours after injury and were, in part, colocalized in neurons showing morphological evidence of apoptosis. These findings suggest that cell cycle-related genes, induced after spinal cord injury, are involved in neuronal damage and subsequent cell death.

Duchenne muscular dystrophy (DMD; dystrophin-deficiency) causes dilated cardiomyopathy in the second decade of life in affected males. We studied the dystrophin-deficient mouse heart (mdx) using high frequency echocardiography, histomorphometry, and gene expression profiling. Heart dysfunction was prominent at 9-10 months of age and showed significantly increased LV internal diameter (end systole) and decreased posterior wall thickness. This cardiomyopathy was associated with a 30% decrease in shortening fraction. Histologically, there was a 10-fold increase in connective tissue volume (fibrosis). mRNA profiling with RT-PCR validation showed activation of key profibrotic genes, including Nox4 and Lox. The Nox gene family expression differed in mdx heart and skeletal muscle, where Nox2 was specifically induced in skeletal muscle while Nox4 was specifically induced in heart. This is the first report of an altered profibrotic gene expression profile in cardiac tissue of dystrophic mice showing echocardiographic evidence of cardiomyopathy.

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