Assessment and outcome of 496 penetrating gastrointestinal warfare injuries.

AIM: The abdominal viscera are among the most vulnerable organs of the body to penetrating trauma. Proper management of such trauma in war victims at the first-line hospital where these victims are first seen is of paramount importance. We reviewed medical records of war victims suffering small bowel and colorectal injuries treated at first, second and third-line hospitals during the Iraq-Iran War (1980-88) to assess surgical outcomes. METHODS: The medical records of 496 Iranian war victims suffering penetrating gastrointestinal (GI) injuries treated at first, second and third-line (tertiary) hospitals, a total of 19 centres, were reviewed. Laparotomy had been performed at the 1st line hospitals for all patients who had an acute abdomen, whose wounds violated the peritoneum or whose abdominal radiographs showed air or shrapnel in the abdominal cavity. Stable patients were transferred from first-line to second-line or from second line to tertiary hospitals postoperatively. The treatments, complications and patient outcomes were documented and analyzed. RESULTS: There were 496 patients; 145, 220 and 131 victims underwent laparotomy for GI injuries at first, second and third-line hospitals respectively. The small intestine and colon respectively were the most prevalent abdominal organs damaged. Those first treated for GI injuries at front-line hospitals (145 victims) had more serious conditions and could not be transferred prior to surgery and presented a higher prevalence of complications and mortality. Overall mortality from GI surgery was 3.6% (18 patients). Eleven patients (7.5%) whose first GI operation was performed at frontline hospitals and 7 patients (3.2%) who underwent their first surgical operation at second-line hospitals died. The most common reason for these deaths was complications relating to the gastrointestinal operation such as anastomotic leak. Six missed injuries were seen at the frontline and one at second line hospitals. There were no deaths at the 3rd line hospitals. CONCLUSION: Penetrating abdominal injuries were common in Iranian victims of war often causing multiple organ injuries. The colon and small intestine were the more commonly injured organs and carried the most postoperative complications. Mortality at 1st line hospitals was more than double that of 2nd line hospitals; the complication rate was also greater as was the number of missed injuries. Adherence to the standard surgical protocols, prompt evaluation, proper triage and management are factors which may lower patient morbidity and complications.

Studies on the mechanism of RNAi-dependent heterochromatin assembly.

Assembly of heterochromatin at centromeric DNA regions in the fission yeast Schizosaccharomyces pombe involves an intimate interplay between chromatin modifying complexes and components of the RNAi pathway. The RNA-induced transcriptional silencing (RITS) complex, containing Chp1, Ago1, Tas3, and centromeric siRNAs, localizes to centromeric DNA repeats and is required for the assembly and maintenance of heterochromatin. RITS brings together two types of molecular recognition modules: a chromodomain protein, which binds to lysine 9 methylated histone H3 (H3K9), and Argonaute, which binds to specific sequences by siRNA-directed base-pairing interactions. The RNA-directed RNA polymerase complex (RDRC), composed of Rdp1, the Hrr1 helicase, and the Cid12 Poly(A) polymerase family member, synthesizes double-stranded RNA and creates the substrate for Dicer to generate siRNAs. RDRC physically associates with RITS, and both complexes localize to noncoding centromeric RNAs and centromeric DNA repeats, suggesting that recognition of nascent RNA transcripts may be involved in localization of these complexes to specific chromosome regions. In support of this possibility, tethering of the RITS complex to the transcript of the normally euchromatic ura4 (+) gene results in siRNA generation and RNAi- and heterochromatin-dependent silencing of the ura4 (+) gene. Finally, silencing of a subset of endogenous and transgene promoters within heterochromatic DNA domains occurs by RNAi-dependent degradation of nascent transcripts by a mechanism that we have termed co-transcriptional gene silencing (CTGS).

Surgical technique for the treatment of high-flow arteriovenous malformations of the mandible.

The high-flow intraosseous arteriovenous malformation is a problematic vascular lesion which may affect bone and the dentition. Variable clinical presentations of this anomaly have resulted in a gamut of treatment modalities being reported ranging from simple curettage, resection, radiotherapy, sclerosing injections, and various forms of embolization, to immediate replantation of the resected segments. Embolization techniques alone have not been universally successful and have often resulted in rapid development of collaterals from surrounding vessels. Definitive treatment has usually involved complete surgical resection (when feasible) either alone, or in combination with other modalities such as embolization. Jaw resection, however, is deforming and leaves a defect often requiring subsequent reconstruction of the hard and soft tissues and replacement of any teeth lost with the resected segment. We report a surgical technique to treat mandibular arteriovenous malformations, which permits ligation of the feeding vessels and provides access allowing for complete removal of the intraosseous lesion. At the same time it not only prevents facial deformity by preserving the mandibular bone and oral soft tissue, but also, and more importantly, may preserve the dentition as well.

Double-strand-break repair recombination in Escherichia coli: physical evidence for a DNA replication mechanism in vivo.

DNA double-strand-break repair (DSBR) is, in many organisms, accomplished by homologous recombination. In Escherichia coli DSBR was thought to result from breakage and reunion of parental DNA molecules, assisted by known endonucleases, the Holliday junction resolvases. Under special circumstances, for example, SOS induction, recombination forks were proposed to initiate replication. We provide physical evidence that this is a major alternative mechanism in which replication copies information from one chromosome to another generating recombinant chromosomes in normal cells in vivo. This alternative mechanism can occur independently of known Holliday junction cleaving proteins, requires DNA polymerase III, and produces recombined DNA molecules that carry newly replicated DNA. The replicational mechanism underlies about half the recombination of linear DNA in E. coli; the other half occurs by breakage and reunion, which we show requires resolvases, and is replication-independent. The data also indicate that accumulation of recombination intermediates promotes replication dramatically.