Tdp1 protects from topoisomerase 1–mediated chromosomal breaks in adult zebrafish but is dispensable during larval development

Deficiency in the DNA end-processing enzyme, tyrosyl-DNA phosphodiesterase 1 (TDP1), causes progressive neurodegeneration in humans. Here, we generated a tdp1 knockout zebrafish and confirmed the lack of TDP1 activity. In adulthood, homozygotes exhibit hypersensitivity to topoisomerase 1 (Top1) poisons and a very mild locomotion defect. Unexpectedly, embryonic tdp1−/− zebrafish were not hypersensitive to Top1 poisons and did not exhibit increased Top1-DNA breaks. This is in contrast to the hypersensitivity of Tdp1-deficient vertebrate models reported to date. Tdp1 is dispensable in the zebrafish embryo with transcript levels down-regulated in response to Top1-DNA damage. In contrast, apex2 and ercc4 (xpf) transcripts were up-regulated. These findings identify the tdp1−/− zebrafish embryo as the first vertebrate model that does not require Tdp1 to protect from Top1-DNA damage and identify apex2 and ercc4 (xpf) as putative players fulfilling this role. It highlights the requirement of distinct DNA repair factors across the life span of vertebrates

Activation of neutrophils within pulmonary microvessels of rabbits exposed to cigarette smoke.

Previous studies have shown that polymorphonuclear leukocytes (PMN) are delayed in the pulmonary capillaries by the presence of cigarette smoke. To determine if the PMN delayed by smoking are activated, we estimated the in vivo expression of CD11/CD18 and L-selectin on the surface of PMN in lungs and peripheral blood of rabbits because these molecules are known to be upregulated and downregulated, respectively, on the surface of activated PMN. New Zealand white rabbits (3.5 +/- 0.1 kg) were exposed to either air (n = 5) or cigarette smoke (n = 5), and we used an established protocol to measure pulmonary vascular blood flow, volume, and red blood cell (RBC) transit time in the left lung. The right lungs were then fixed in 0.025% glutaraldehyde and stored in liquid nitrogen. Ultrathin sections were immuno-labeled with either the anti-CD18 monoclonal antibody 60.3 or the anti-L-selectin antibody Dreg-200, followed by a secondary antibody conjugated to 10 nm colloidal gold. The target antigens were quantified by counting the number of gold particles per micron (G/microns) of PMN surface membrane. The data show that smoke exposure had no effect on pulmonary blood flow, volume, or RBC transit time. However, it increased the expression of CD11/CD18 on intravascular PMN in the upper region of the lung (control, 7.4 +/- 1.3 G/microns; smoke-exposed, 13.2 +/- 3.3 G/microns; P < 0.05) and decreased the expression of L-selectin on intravascular PMN in both the lower (control, 5.5 +/- 2.0 G/microns; smoke-exposed, 2.6 +/- 1.5 G/microns; P = 0.05) and the upper (control, 6.8 +/- 1.4 G/microns; smoke-exposed, 2.6 +/- 1.2 G/microns; P < 0.05) regions

Investigation of the role of VHL-HIF signaling in DNA repair and apoptosis in zebrafish

pVHL is a tumor suppressor. The lack of its function leads to various tumors, among which ccRCC (clear cell renal cell carcinoma) has the most serious outcome due to its resistance to chemotherapies and radiotherapies. Although HIF promotes the progression of ccRCC, the precise mechanism by which the loss of VHL leads to tumor initiation remains unclear. We exploited two zebrafish vhl mutants, vhl and vll, and Tg (phd3:: EGFP)i144 fish to identify crucial functions of Vhl in tumor initiation. Through the mutant analysis, we found that the role of pVHL in DNA repair is conserved in zebrafish Vll. Interestingly, we also discovered that Hif activation strongly suppressed genotoxic stress induced DNA repair defects and apoptosis in vll and brca2 mutants and in embryos lacking ATM activity. These results suggest the potential of HIF as a clinical modulator that can protect cells from accumulating DNA damage and apoptosis which can lead to cancers and neurodegenerative disorders

Second generation lethality in RNAseH2a knockout zebrafish

Removal of ribonucleotides from DNA by RNaseH2 is essential for genome stability, and its impacted function causes the neurodegenerative disease, Aicardi Goutières Syndrome. We have created a zebrafish rnaseh2a mutant to model this process. Surprisingly, RNaseH2a knockouts show little phenotypic abnormality at adulthood in the first generation, unlike mouse knockout models, which are early embryonic lethal. However, the second generation offspring show reduced development, increased ribonucleotide incorporation and upregulation of key inflammatory markers, resulting in both maternal and paternal embryonic lethality. Thus, neither fathers or mothers can generate viable offspring even when crossed to wild-type partners. Despite their survival, rnaseh2a−/− adults show an accumulation of ribonucleotides in both the brain and testes that is not present in early development. Our data suggest that homozygotes possess RNaseH2 independent compensatory mechanisms that are inactive or overwhelmed by the inherited ribonucleotides in their offspring, or that zebrafish have a yet unknown tolerance mechanism. Additionally, we identify ribodysgenesis, the rapid removal of rNMPs and subsequently lethal fragmentation of DNA as responsible for maternal and paternal embryonic lethality

Circulating acute phase reactive proteins as indicators of infection in poorly controlled diabetes mellitus

Serum levels of six acute phase proteins (APP) - C-reactive protein (CRP), serum amyloid A (SAA), α1-antitrypsin, haptoglobin and complement fractions C3 and C4 - were serially studied in 24 patients with poorly controlled diabetes mellitus, ten of whom had unequivocal evidence of an underlying infection. In diabetic patients without infection, no change in APP levels was noted suggesting that hyperglycaemia per se does not quantitatively influence the acute phase response. No correlation between the presence of infection, and fever, leukocytosis, a raised erythrocyte sedimentation rate, or serum levels of α1-antitrypsin, haptoglobin or complement was apparent in these patients. However, serum CRP and SAA were initially increased 10-100 times above normal in diabetic patients with an underlying infection (P &lt; 0.01); during the following week circulating levels of CRP and SAA decreased steadily in response to the infection being brought under control. We conclude that serial measurement of CRP and/or SAA is a sensitive, albeit non-specific, parameter to detect and monitor the activity of infection in patients with diabetes.Articl

Treatment of multiple rib fractures. Randomized controlled trial comparing ventilatory with nonventilatory management

We studied the treatment of multiple rib fractures in NIC, comparing ventilatory with nonventilatory methods in 69 patients who were randomly allocated to one of the following two treatments: (1) a CPAP mask combined with regional analgesia (n = 36); or (2) endotracheal intubation and mechanical ventilation with PEEP (n = 33). Clinical outcome was as follows: mean duration of treatment, 4.5 ± 2.3 days for the group with CPAP and 7.3 ± 3.7 days for the intubated group (p = 0.0003); mean number of days spent in intensive care, 5.3 ± 2.9 days and 9.5 ± 4.4 days, respectively (p = < 0.0001); mean period of hospitalization, 8.4 ± 7.1 days and 14.6 ± 8.6 days, respectively (p = 0.0019); and patients developing complications: 28 percent (10/36) and 73 percent (24/33), respectively. Infections caused the difference in complications, primarily pneumonias, which occurred in 14 percent (5/36) of the group with CPAP but in 48 percent (16/33) of the intubated group. We conclude that treatment with a CPAP mask combined with regional analgesia can shorten and simplify treatment in these patients, mainly through a decreased infection rate, when compared with intubation and mechanical ventilation, and we recommend this treatment in patients similar to our sample.Articl

Community-acquired pneumonia: Evidence of functional inactivation of α1 proteinase inhibitor

Quantitative and qualitative elastase inhibitory capacity (EIC) α1 proteinase inhibitor (α1PI) was measured in pulmonary arterial and systemic arterial blood of patients with community-acquired pneumonia (CAP). Eleven patients with uncomplicated CAP were compared with 16 patients with fulminating pneumonia requiring intensive care management. An appropriate increase in quantitative α1PI was demonstrated in all patients. A significant functional inactivation of α1PI was demonstrated in the ICU-treated patients that was not apparent in the uncomplicated CAP patients (p &lt; .01). This low EIC returned to normal 4 wk after hospital discharge in all survivors. A significant (p &lt; .02) difference in EIC between the pulmonary arterial and systemic arterial blood was found in the nonsurvivors on admission, which suggests that α1PI is inactivated in the lungs of patients with fulminating CAP. The present data demonstrate that α1PI is functionally inactivated in patients with fulminating CAP. This low serum functional α1PI may result in proteolytic lung damage and an unfavorable outcome.Articl