Dylan Stewart

Genetic Contribution To The Septic Response In A Mouse Model

The response to injury is dependent on several factors, including the type and extent of the injury, genetics, and the environment. In the present study, the genetic contribution to sepsis was evaluated in a mouse model. Sepsis was induced in two inbred mouse strains, C57BL/6J (B6) and A/J, by cecal ligation and single puncture (CLP). Frequency of mortality was significantly higher in B6 than A/J mice from 36 to 132 h after CLP. Plasma TNF-&agr;, IL-1&bgr;, and IL-6 levels were similar in both strains after CLP. IL-10 plasma levels were significantly higher in B6 mice as opposed to A/J mice after 24 h of CLP. Similarly, hepatic myeloperoxidase activity, an index of polymorphonuclear leukocytes, was elevated in B6 mice as compared with A/J mice after 24 h of CLP. On the contrary, metallothionein mRNA levels were higher in A/J mice compared with B6 mice. Finally, leptin levels were also higher in A/J than B6 mice within 19 h of CLP. This study demonstrates a genetic contribution in the response to sepsis.

Genetic background conditions the effect of sex steroids on the inflammatory response during endotoxic shock.

ObjectiveThe contribution of gender to the mortality and morbidity of trauma patients is controversial. In addition, a genetic contribution has been recently indicated. The influence of these two variables was studied in a murine model of endotoxemia. DesignProspective, controlled, and randomized animal study. SettingA university research laboratory. SubjectsFemale and male mice (6–8 wks old) were injected with Escherichia coli lipopolysaccharide (15 mg/kg). Additionally, mice were gonadectomized and supplemented with 5-&agr;-dihydrotestosterone (357 mg/day), 17-&bgr;-estradiol (23.8 &mgr;g/day), or placebo for 21 days and injected with lipopolysaccharide. Tumor necrosis factor-&agr; was measured in plasma samples obtained after 1.5 hrs of lipopolysaccharide injection. Measurements and Main ResultsHigher tumor necrosis factor-&agr; plasma levels were observed in C57BL/6J (B6) female mice as compared with males. Because this phenotype is not sex linked, we evaluated the role of sex steroids. Castrated male B6 mice showed higher lipopolysaccharide-induced tumor necrosis factor-&agr; plasma levels than nonoperated controls. These lipopolysaccharide-induced tumor necrosis factor-&agr; levels were further increased after the administration of 17-&bgr;-estradiol to castrated B6 male mice as compared with nonoperated male or female mice. In addition, 17-&bgr;-estradiol-supplemented castrated mice showed a higher frequency of mortality than castrated males without hormone replacement or nonoperated mice. Analysis of castrated male mice from other strains (A/J, DBA/2J, AKR/J, BALB/cJ) supplemented with 17-&bgr;-estradiol presented the opposite effect, a reduction in lipopolysaccharide-induced tumor necrosis factor-&agr; plasma levels. ConclusionsThese results suggest that sex steroids can modulate the inflammatory response and the outcome after injury in mice. The effect of sex steroids depends on the genetic background.

Age at presentation of common pediatric surgical conditions: Reexamining dogma

PURPOSE The commonly cited ages at presentation of many pediatric conditions have been based largely on single center or outdated epidemiologic evidence. Thus, we sought to examine the ages at presentation of common pediatric surgical conditions using cases from large national databases. METHODS A retrospective analysis was performed on Healthcare Cost and Utilization Project databases from 1988 to 2009. Pediatric discharges were selected using matched ICD9 diagnosis and procedure codes for malrotation, intussusception, hypertrophic pyloric stenosis (HPS), incarcerated inguinal hernia (IH), and Hirschsprung disease (HD). Descriptive statistics were computed. RESULTS A total of 63,750 discharges were identified, comprising 2744 cases of malrotation, 5831 of intussusception, 36,499 of HPS, 8564 of IH, and 10,112 of HD. About 58.2% of malrotation cases presented before age 1. Moreover, 92.8% of HPS presented between 3 and 10weeks. For intussusception, 50.3% and 91.4% presented prior to ages 1 and 4years, respectively. Also, 55.8% of IHD cases presented before their first birthday. For HD, 6.5% of cases presented within the neonatal period and 45.9% prior to age 1year. CONCLUSION Our findings support generally cited presenting ages for HPS and intussusception. However, the ages at presentation for HD, malrotation, and IH differ from commonly cited texts.

Promoter activity of the rat connexin 43 gene in NRK cells.

Cellular communication mediated by gap junctions plays a major role in organ function. Gap junction channels are formed by the organization of polypeptide subunits, termed connexins (Cx), on the cell surface of adjacent cells. One mechanism to regulate gap‐junctional communication is by change in Cx expression. In the present study, the promoter region of the rat Cx43 gene was characterized. Nested deletions of the 5′ flanking region of the first Cx43 exon were coupled to the human growth hormone gene and transfected into normal rat kidney (NRK) cells, that express this gene constitutively. The minimal region of the Cx43 gene that showed maximal promoter activity was localized within 110 bp upstream of the transcriptional initiation site. One particular subregion that contains a Sp‐1 binding site (located within 98–93 bp from the transcriptional initiation site) was found to sustain Cx43 promoter activity to the same extent as that of the 110 bp promoter region. Mutations of this Sp‐1 binding site abolished transcriptional activity and DNA–protein interactions. These observations suggest that the Sp‐1 binding site plays a major role in the basal transcriptional activity of Cx43 gene in NRK cells. J. Cell. Biochem. 81:514–522, 2001.

Helicopter Overtriage in Pediatric Trauma

BACKGROUND Helicopter Emergency Medical Services (HEMS) have been designed to provide faster access to trauma center care in cases of life-threatening injury. However, the ideal recipient population is not fully characterized, and indications for helicopter transport in pediatric trauma vary dramatically by county, state, and region. Overtriage, or unnecessary utilization, can lead to additional patient risk and expense. In this study we perform a nationwide descriptive analysis of HEMS for pediatric trauma and assess the incidence of overtriage in this group. METHODS We reviewed records from the American College of Surgeons National Trauma Data Bank (2008-11) and included patients less than 16 years of age who were transferred from the scene of injury to a trauma center via HEMS. Overtriage was defined as patients meeting all of the following criteria: Glasgow Coma Scale (GCS) equal to 15, absence of hypotension, an Injury Severity Score (ISS) less than 9, no need for procedure or critical care, and a hospital length of stay of less than 24 hours. RESULTS A total of 19,725 patients were identified with a mean age of 10.5 years. The majority of injuries were blunt (95.6%) and resulted from motor vehicle crashes (48%) and falls (15%). HEMS transported patients were predominately normotensive (96%), had a GCS of 15 (67%), and presented with minor injuries (ISS<9, 41%). Overall, 28 % of patients stayed in the hospital for less than 24 hours, and the incidence of overtriage was 17%. CONCLUSIONS Helicopter overtriage is prevalent among pediatric trauma patients nationwide. The ideal model to predict need for HEMS must consider clinical outcomes in the context of judicious resource utilization. The development of guidelines for HEMS use in pediatric trauma could potentially limit unnecessary transfers while still identifying children who require trauma center care in a timely fashion.

PROTECTION FROM LETHAL ENDOTOXIC SHOCK AFTER TESTOSTERONE DEPLETION IS LINKED TO CHROMOSOME X

Men are considered more susceptible to sepsis after severe injury than are women, which has been attributed to a suppressing effect of male sex steroids on the inflammatory response. Moreover, the effect of sex steroids on the inflammatory process depends on the genetic background. The present study examined the genetic contribution to survival after endotoxic shock in mice depleted of testosterone by surgical castration. Six-week-old male mice, from strains A/J, AKR/J, C57BL/6J (B6), BALBc/J, DBA/2J, and C3H/HeN, were castrated (CX) or nonoperated (NoOp). Two weeks after surgery, mice were injected intraperitoneally with Escherichia coli lipopolysaccharide (15 mg/kg) and the frequency of mortality was monitored. CX A/J mice showed a significantly higher survival rate than NoOp mice, but this protective effect was not observed in the other strains. Administration of 5-α-dihydrotestosterone to CX A/J mice reverted the protection by CX. The protective effect of CX was also observed in crosses of female A/J and male B6 (AXB), but not female B6 and male A/J (BXA), suggesting that protection is linked to the A/J X chromosome. This possibility was corroborated by using consomic mice containing A/J chromosome X and the remaining chromosomes from B6. These results suggest that testosterone is a negative factor in the recovery from endotoxic shock, depending on the genetic background.

The combination of polymicrobial sepsis and endotoxin results in an inflammatory process that could not be predicted from the independent insults

BACKGROUND The variable clinical profile observed in critically ill patients is the result of multiple factors. Genetic determinants have recently been shown as confounding factors in the response to injury. However, other elements, such as the environment and the type of injury, could modify this response. The objective of this investigation was to study the effect of combining insults and different genetic backgrounds on the inflammatory response. MATERIALS Male mice, C57BL/6J (B6) and A/J, were randomized to undergo cecal ligation and single puncture (CLP) or sham operation (SOP). After 24 h of recovery, mice were randomized again into two groups, one group was injected with bacterial lipopolysaccharide (LPS; 15 mg/kg) and the other was injected with normal saline (NS). An additional experimental group included mice that were not operated (NOP) and injected with LPS. Mice were evaluated by plasma cytokine content. RESULTS The combination of insults resulted in an apparent additive effect for some cytokines, such as interleukin (IL) 6. In contrast, tumor necrosis factor alpha (TNF-alpha) was considerably lower in the combined injury group with respect to injection of LPS alone. There was no relevant difference in IL-10 levels between any group, except that its decay was slower in the CLP + LPS group. Overall, cytokine levels were different between B6 and A/J mice indicating a genetic contribution. CONCLUSIONS These results indicate that the response to stress is the combination of the type of injury and the genetic background of the subject. These observations also illustrate the difficulty in predicting the inflammatory response and underlying mechanism based on cytokine plasma levels.

Utilization of a novel unidirectional knotless suture during minimal access procedures in pediatric surgery

BACKGROUND The application of minimally invasive surgery (MIS) for advanced procedures in children is logical. However, the intracorporeal placement and tying of suture can be challenging, leading to prolonged anesthesia and morbidity. We describe our initial experience with the use of a novel unidirectional barbed knotless suture (V-LOC, Covidien, Mansfield, MA) that permits a safe and efficient advanced MIS reconstruction in infants and children. METHODS From August 2010 to February 2012, 11 infants and children underwent diaphragmatic reconstruction utilizing either the absorbable or the permanent V-LOC suture. Data retrieval included gender, weight, diagnosis, operative time, complications and follow up. RESULTS Thoracoscopic or laparoscopic repairs were carried out in all children. Two of the infants with congenital diaphragmatic hernia of Bochdalek (CDH) developed a recurrence at 4 and 6 months of age and required reoperation. There were no other complications or recurrence in the remaining 9 children, and there were no mortalities in the group. CONCLUSION This is the first study to evaluate the use of the unidirectional barbed knotless suture in pediatric surgery. We demonstrate that the use of the V-LOC barbed suture is an innovative, safe and time saving option for pediatric MIS. Prospective analysis with long-term follow-up is required to confirm these initial results and to ascertain if this novel approach can be utilized in other pediatric surgical conditions.

Pediatric surgical complications of major genitourinary reconstruction in the exstrophy–epispadias complex

PURPOSE Urinary continence is the goal of exstrophy-epispadias complex (EEC) reconstruction. Patients may require a continent urinary diversion (CUD) if they are a poor candidate for bladder neck reconstruction or are receiving an augmentation cystoplasty (AC) or neobladder (NB). This study was designed to identify the incidence of surgical complications among various bowel segments typically used for CUD. METHODS A prospectively kept database of 1078 patients with EEC at a tertiary referral center from 1980 to 2012 was reviewed for major genitourinary reconstruction. Patient demographics, surgical indications, perioperative complications, and outcomes were recorded. RESULTS Among reviewed EEC patients, 134 underwent CUD (81 male, 53 female). Concomitant AC was performed in 106 patients and NB in 11. Median follow up time after initial diversion was 5 years. The most common CUD bowel segments were appendix and ileum. The most common surgical complications after CUD were small bowel obstruction, post-operative ileus, and intraabdominal abscess. There was a significantly increased risk in the occurrence of pelvic or abdominal abscess when colon was used as a conduit compared to all other bowel segments (OR=16.7, 95% CI: 1.16-239) and following NB creation compared to AC (OR=39.4, 95% CI: 3.66-423). At postoperative follow-up, 98% of patients were continent of urine via their stoma. CONCLUSION We report the largest series to date examining CUD in the EEC population. The increased risk of abdominal and pelvic abscesses in patients who receive a colon CUD and undergo NB compared to AC indicates that while surgical complications following major genitourinary reconstruction are rare, they do occur. Practitioners must be wary of potential complications that are best managed by a multi-disciplinary team approach.

ErratumThe incorrect version of the below article was published in the November 2014 issue (J Pediatr Surg 2014;49(11):1673-7). The correct version of the article appears below.Helicopter overtriage in pediatric trauma

Background Helicopter Emergency Medical Services (HEMS) have been designed to provide rapid access to trauma center care in cases of life-threatening injury. However, the ideal recipient population of this resource is not fully characterized, and the indications for helicopter transport in pediatric trauma vary dramatically by county, state, and region. Overtriage, or unnecessary utilization, can lead to additional patient risk and healthcare expense. In this study we perform a nationwide descriptive analysis of HEMS for pediatric trauma and assess the incidence of overtriage in this group.