Administration of substances to laboratory animals requires careful consideration and planning to optimize delivery of the agent to the animal while minimizing potential adverse experiences from the procedure. For all species, many different routes are available for administration of substances. The research team and IACUC members should be aware of reasons for selecting specific routes and of training and competency necessary for personnel to use these routes effectively. Once a route is selected, issues such as volume of administration, site of delivery, pH of the substance, and other factors must be considered to refine the technique. Inadequate training or inattention to detail during this aspect of a study may result in unintentional adverse effects on experimental animals and confounded results.

Administration of substances to laboratory animals: routes of administration and factors to consider.

Intraperitoneal (IP) route of drug administration in laboratory animals is a common practice in many in vivo studies of disease models. While this route is an easy to master, quick, suitable for chronic treatments and with low impact of stress on laboratory rodents, there is a common concern that it may not be an acceptable route for drug administration in experimental studies. The latter is likely due to sparsity of information regarding pharmacokinetics of pharmacological agents and the mechanisms through which agents get systemic exposure after IP administration. In this review, we summarize the main mechanisms involved in bioavailability of IP administered drugs and provide examples of pharmacokinetic profiles for small and large molecules in comparison to other routes of administration. We conclude with a notion that IP administration of drugs in experimental studies involving rodents is a justifiable route for pharmacological and proof-of-concept studies where the goal is to evaluate the effect(s) of target engagement rather than properties of a drug formulation and/or its pharmacokinetics for clinical translation.

/pdf/intraperitoneal-route-of-drug-administration-should-it-be-2zrpws0uv8.pdf

Intraperitoneal Route of Drug Administration: Should it Be Used in Experimental Animal Studies?

Background: Correct determination of nodal status is pivotal to accurate staging and predicting survival. Methods: This is a secondary analysis of INT0089, an intergroup trial of adjuvant chemotherapy for high-risk stage II and III colon cancer. A subset of patients was studied who underwent right or left hemicolectomy and from whom at least 10 lymph nodes were examined. A mathematical model was created to estimate the probability of a true negative result on the basis of the number of nodes examined. The number of nodes needed to predict nodal negativity with 85%, 50%, and 25% probability on the basis of tumor stage was calculated. Results: In this analysis, 1585 patients were studied. The average number of nodes removed at surgery was comparable between treatment groups at 18.5 (median of 16 in all groups). With this model, when 18 nodes are removed at resection, there is a <25% probability of true node negativity in T1/T2 tumors, whereas <10 nodes need to be examined in T3 and T4 tumors to achieve the same probability. Conclusions: Tumor stage and the number of nodes retrieved at resection influence the accuracy of determining nodal status in colon cancer. Most patients are understaged. Underestimating nodal stage may influence decisions regarding adjuvant therapy, as well as overall prognosis.

Accuracy of determining nodal negativity in colorectal cancer on the basis of the number of nodes retrieved on resection.

Perioperative Management of Pheochromocytoma

One of the most commonly observational study designs employed in veterinary is the cross-sectional study with binary outcomes. To measure an association with exposure, the use of prevalence ratios (PR) or odds ratios (OR) are possible. In human epidemiology, much has been discussed about the use of the OR exclusively for case-control studies and some authors reported that there is no good justification for fitting logistic regression when the prevalence of the disease is high, in which OR overestimate the PR. Nonetheless, interpretation of OR is difficult since confusing between risk and odds can lead to incorrect quantitative interpretation of data such as "the risk is X times greater," commonly reported in studies that use OR. The aims of this study were (1) to review articles with cross-sectional designs to assess the statistical method used and the appropriateness of the interpretation of the estimated measure of association and (2) to illustrate the use of alternative statistical methods that estimate PR directly. An overview of statistical methods and its interpretation using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted and included a diverse set of peer-reviewed journals among the veterinary science field using PubMed as the search engine. From each article, the statistical method used and the appropriateness of the interpretation of the estimated measure of association were registered. Additionally, four alternative models for logistic regression that estimate directly PR were tested using our own dataset from a cross-sectional study on bovine viral diarrhea virus. The initial search strategy found 62 articles, in which 6 articles were excluded and therefore 56 studies were used for the overall analysis. The review showed that independent of the level of prevalence reported, 96% of articles employed logistic regression, thus estimating the OR. Results of the multivariate models indicated that logistic regression was the method that most overestimated the PR. The findings of this study indicate that although there are methods that directly estimate PR, many studies in veterinary science do not use these methods and misinterpret the OR estimated by the logistic regression.

/pdf/odds-ratio-or-prevalence-ratio-an-overview-of-reported-2zk7ehyw7b.pdf

Odds Ratio or Prevalence Ratio? An Overview of Reported Statistical Methods and Appropriateness of Interpretations in Cross-sectional Studies with Dichotomous Outcomes in Veterinary Medicine.

In clinical studies, the relative likelihood of an event occurring between 2 groups is often expressed as the risk ratio (RR) or the odds ratio (OR). The RR is an intuitive parameter that is relatively easy to interpret. Quantitative interpretation of an OR is much more difficult and is often incorrectly equated to that of an RR. The problem is that OR may differ substantially from RR, especially when the outcome of interest is common in the study population. This article explains and clarifies controversial issues surrounding the use and interpretation of the OR. Theoretical concepts relating to ORs are illustrated by examples from the surgical literature. By reviewing articles from 5 surgical journals over a 5-year period, we show that the OR is often presented and misinterpreted as equivalent to the RR. When the discrepancy is large, using OR uncritically as an estimate of RR will strongly bias inferences about treatment effect or cause of disease by amplifying the apparent strength of an association between an exposure and an outcome.

http://canjsurg.ca/wp-content/uploads/2014/03/48-5-400.pdf

What is so odd about odds

BACKGROUND Because heat can improve the activity of selected drugs when administered heated in the peritoneal cavity in the treatment of peritoneal carcinomatosis from colorectal origin, there is a great interest to evaluate new cytotoxic agents in this context. The purpose of this study is to assess the effect of heat on the pharmacokinetic profile of Raltitrexed administered intraperitoneally in rats. MATERIAL/METHODS Rats #1 to #40 have been submitted to different doses of intraperitoneal Raltitrexed (2, 4, and 8 mg/m2) at different perfusion temperatures (37, 40 and 43 degrees C). After 25 minutes of perfusion, peritoneal fluid, portal and systemic blood were harvested and prepared for dosage of Raltitrexed. Rats #41 to #50 have been submitted to 8 mg/m2 of intraperitoneal Raltitrexed (37 and 43 degrees C) during 25 minutes. Then, a segment of small bowel and a section of parietal peritoneum were harvested and prepared for intracellular dosage of Raltitrexed. RESULTS The dose of Raltitrexed administered is a determinant of its concentration in peritoneal perfusate, in portal vein blood and in systemic blood (p < 0.0002). We noticed that perfusate temperature had no significant effect on the concentration of drug in the portal vein blood (p = 0.29) and in the systemic blood (p = 0.25). However, temperature increased significantly (p < 0.04) the intracellular absorption of Raltitrexed. CONCLUSIONS Because the effect of Raltitrexed is proportional to its intracellular concentration, it seems clear that Raltitrexed is of greatest interest when administered heated in the peritoneum because it can reach greater intracellular concentrations without a significant increase in systemic concentration, which is responsible of toxicity.

A study of the effect of temperature on the pharmacokinetic profile of raltitrexed administered by intraperitoneal route in the rat.

liters of free blood and major injuries to the right kidney, head of the pancreas, duodenum, and transection of the superior mesenteric vein were found. The trauma team performed ligation of the mesenteric vein, right nephrectomy, and a pancreaticoduodenectomy with reconstruction of the gastrointestinal tract. At the end of his initial laparotomy lasting 4 hours, the patient was severely coagulopathic, hypothermic, acidotic, and developed massive bowel edema. The abdominal packing was performed, and after resuscitation, secondary closure was performed 36 hours later. A high-output, proximal intestinal fistula developed on postoperative day 7. The patient was started on parenteral nutrition, and central venous catheters were inserted or changed over the next 3 weeks. Bacteremia secondary to line sepsis occurred, leading to endocarditis, and septic shock, and a massive stroke led to the death of the patient on postoperative day 34. I would differ with the decision of the trauma team to persist with a prolonged surgical procedure and even perform reconstructive surgery in the presence of major vascular injury and shock. If I were the plaintiff’s expert witness, I would point out the principle of damage control laparotomy in the care of this patient. Damage control laparotomy has been a well established and recommended procedure for nearly two decades. Here, the primary aim should have been to control bleeding and perform temporary closure and take the patient to the intensive care unit for resuscitation. Major resectional or reconstructive surgery should have been undertaken only when patient was resuscitated and stable. Postoperative morbidity and mortality are known to be unacceptably high when prolonged surgical procedures are performed in unstable patients. By following the well established principles of damage control laparotomy and delayed reconstruction of the gastrointestinal tract after pancreaticoduodenectomy, the likelihood of postoperative intraabdominal complications could be reduced. So, the scenario discussed here raises not only the concern about following the guidelines recommended for insertion and management of central venous line sepsis, but also about the initial surgical care provided to this patient.

Laparoscopic Colorectal Surgery in Elderly Patients: A Matched Case-Control Study in 178 Patients

Introduction: Early feeding within 24 hours of intestinal surgery seems advantageous in terms of reduction of wound infection, pneumonia and length of hospital stay. The aim of the study is to evaluate the impact of early enteral nutrition in length of hospital stay in comparison to traditional postoperative feeding regimen. Method: This prospective study enrolled 95 patients randomized in two groups: control group patients receive enteral feeding in absence of nausea or vomiting, abdominal distension and after passage of flatus or stools, while patients in experimental group were fed a liquid diet within 12 hours of surgery, followed by a regular diet at the next meal. The primary endpoint was the impact of early oral feeding on hospital length of stay. The secondary endpoint was to measure the impact of the diet reintroduction modality on the incidence of early postoperative morbidity and return of bowel function. Result: Length of hospital stay was slightly diminished in the experimental group compared to control (8.78 ± 3.85 versus 9.41 ± 5.22), but the difference was not statistically significant. Postoperative nausea and vomiting were reported in 24 (51.0%) patients in experimental group and 30 (62.5%) in control group. Only one patient required nasogastric tube insertion. The majority of patients did not demonstrate any postoperative morbidity in both groups. Conclusion: Early enteral nutrition is safe after intestinal surgery. However we did not demonstrate that early enteral feeding diminished length of hospital stay or hastened the return of bowel function.

/pdf/impact-of-early-postoperative-enteral-feeding-on-hospital-30nbrlax9v.pdf

Impact of Early Postoperative Enteral Feeding on Hospital Length of Stay in Patients Undergoing Colonic Surgery: Results of a Prospective Randomized Trial

Biomechanical Comparison of Small Versus Large Bites for the Closure of a Midline Incision in a Synthetic Abdominal Wall

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