Ischemic Preconditioning Preserves Liver Energy Charge and Function on Hepatic Ischemia/Reperfusion Injury in Rats.

BACKGROUND: Cell energy during ischemia/reperfusion depends on mechanisms including adenosine diphosphate degradation, oxygen species and cytokine liberation, neutrophil infiltration, and endothelial dysfunction. Preconditioning-a brief ischemic episode that confers a state of protection against subsequent ischemia-reperfusion injury-involves NO and adenosine production, reduction in oxygen species liberation, and preservation of microcirculation. During hypoxia, constitutive NO production assures adequate oxygen delivery and reduced energy loss. The aim was to determine the role of ischemic preconditioning in the stimulation of constitutive endothelial nitric oxide (NO) production and its effect on energy charge, radical oxygen species generation, cytokine liberation, and neutrophil infiltration during reperfusion. MATERIALS AND METHODS: Rats were assigned to one of four groups depending on the preconditioning protocol: hepatic ischemia/reperfusion, or hepatic ischemia/reperfusion and ischemic preconditioning, for 5, 10, or 20 min. A portosystemic shunt was established between the portal and left jugular veins during ischemia. RESULTS: Preconditioning produced rises in plasma nitrites, but no rise in inducible nitric oxide synthase gene expression. A 5 or 10 min preconditioning period allowed for higher energy charge, bile production, and glutathione levels, with less lipoperoxide, alanine aminotransferase, tumor necrosis factor-α, and interleukin-1 production and neutrophil infiltration, compared with 20 min or control. Survival was 80% in the G10 group, 70 in G5, 10 in GC, and 0% in the G20 group. CONCLUSIONS: Ten-min liver preconditioning improves survival and prevents energy loss during hepatic ischemia/reperfusion by stimulating constitutive NO production, maintaining glutathione concentrations and reducing oxygen species and proinflammatory cytokine generation as well as neutrophil infiltration.

[Impact of vacuum-assisted closure management in deep neck abscesses]. / Impacto del manejo con cierre asistido al vacío en abscesos profundos de cuello.

BACKGROUND: The presence of deep neck abscesses is potentially serious; they can lead to death in a short period of time. The vacuum-assisted closure (V.A.C.) therapy has been used in many areas of surgery for complex wound healing. This treatment modality has recently been considered in the field of head and neck surgery. OBJECTIVE: Evaluate the efficacy of healing therapy using V.A.C. therapy in deep neck abscesses. MATERIAL AND METHODS: Open-label trial. Patients with deep neck abscesses were included using V.A.C. therapy versus conventional therapy. Cultures were taken before and during surgery, and prior to primary wound closure. The percentages of healing, viable tissue, wound healing time, and hospital stay were evaluated. RESULTS: A total of 18 patients were included. Affected neck spaces: submaxilar 29%, parapharyngeal 22%, submental 21% and masticatory 13%. The final postsurgical culture was negative in 78%. Viable tissue of the wound for the V.A.C. group was 42%, and for the control group was 36% (p=0.025). Healing time was 22±6 days and 38±15.5, respectively (p = 0.01). The mean number of hospital stay was 12 days for both groups. CONCLUSIONS: Therapy with V.A.C. is useful in the treatment of deep neck abscesses; it decreased healing time as a result of more viable tissue allowing suture closure of the wound in a shorter period.

[Larrea tridentata. Effect on a non-metabolic model of urolithiasis in rats]. / Larrea tridentata en urofitiasls. Efecto en un modelo no metabólico en ratas.

OBJECTIVE: To evaluate the effect of L. tridentata infusion on the development of urinary calculi in a non-metabolic model. METHODS: Male Wistar rats were divided into two groups (n = 10 each). The experimental group received 1 mL of oral L. tridentata infusion three times daily for 95 days. Control group received 1 mL tap water. Five days after initiating treatment, urolithiasis was induced inserting a series of 15 knots of 5-0 chromic catgut into the urinary bladder. Measurements included body weight and water intake, complete blood counts, glucose, BUN, creatinine, bacterial culture, and weight of urinary stones and sands. RESULTS: No statistically significant differences were found between groups for any variable. CONCLUSIONS: An infusion of L. tridentata was not effective in the prevention of urolith formation in the suture-induced rat model. It produced no alterations in body weight gain, blood counts, or water intake. Future work is needed to completely rule out any effect of the plant on urolith formation.

Activated clotting time and heparin administration in Sprague-Dawley rats and Syrian golden hamsters.

To determine the activated clotting time (ACT) in rats and hamsters from our colony and to evaluate the response of this parameter to different heparin doses in these species, ACTs were measured using a Medtronic HemoTec ACT measurement system in samples obtained by intracardiac puncture from normal, nonanticoagulated, anesthetized rats and hamsters. Another groups of animals received different intravenous boluses of heparin to determine the dose needed to maintain ACT values > 480 sec for at least 30 min. The ACT (mean +/- SEM) was 48.0 +/- 2.17 sec for the 50 rats sampled and 42.5 +/- 2.35 sec for the 48 hamsters. Rats required a bolus of 1200 IU/kg intravenous heparin to maintain an ACT > 480 sec for 30 min; hamsters required 1000 IU/kg heparin for the same effect. We concluded that compared with humans, rats and hamsters from our colony have short ACTs and low sensitivity to heparin, in terms of the dose needed to reach a target ACT as well as the time required to sustain it. Further the ACT values in these animals showed great variability.

Melatonin ameliorates renal ischemia/reperfusion injury.

BACKGROUND: We studied whether melatonin is able to reduce organ damage during renal ischemia/reperfusion via its effects on the oxidative response in early and late reperfusion. MATERIALS AND METHODS: Renal ischemia/reperfusion injury (I/R) was induced in two groups of rats by 75 min occlusion of the left renal artery and vein and right nephrectomy, followed by reperfusion. The formation of reactive oxygen species was evaluated in the early reperfusion phase (60 min) by lipid peroxidation products and glutathione assay. In the late reperfusion phase (24 h) tissue neutrophil infiltration, inducible nitric oxide synthase (iNOS) gene expression, and histopathology were evaluated. Groups received either systemic melatonin (MEL) or normal saline (NS). There were two nonischemic sham control groups, one with and another without melatonin (S+MEL and S). RESULTS: Creatinine was higher in the NS group at all times. A reduction in glutathione and increases in lipid peroxidation products and myeloperoxidase activity induced by I/R indicated renal injury involving reactive oxygen formation. Melatonin reversed this oxidant response and reduced the rise in creatinine and iNOS expression. Seven-day group survivals were 5/10 for NS, 8/10 for MEL, and 10/10 for both Sham groups. CONCLUSIONS: Exogenous melatonin is able to preserve renal functional status following I/R-induced injury by increasing glutathione and reducing lipid peroxidation in the early reperfusion phase, without any apparent effect on neutrophil infiltration in the late reperfusion phase.

Cambios en los gases ateriales de perros de raza Beagle durante el neumoperitoneo con bióxido de carbono / Changes in arterial blood gases from Beagles during carbono dioxide pneumoperitoneum

La laparoscopia es una alternativa común en humanos para la resolución de patología quirúrgica. Su uso en medicina veterinaria tiene a aumentar: Aunque se conocen las alteraciones gasométricas en animales adultos sometidos a neumoperitoneo con CO2, se diseñó este trabajo con el fin de valorar dichas alteraciones específicamente en perros de menos de 10 kg de peso. Cuatro de estos últimos, de raza Beagle, adultos, de entre 6 y 9 kg fueron sometidos a anestesia, ventilación de presión y neumoperitoneo con CO2 a 8 mmHg de presión durante 75 min. Se observó elevación significativa (P < 0.05) de la PaCO2 desde valores normales, hasta 51.6 ñ 1.28 mmHg, con una reducción simultánea del pHa hasta 7.29 ñ 0.02 (P < 0.05). La hiperventilación durante los últimos 50 min tendió a corregir estos valores. La PaO2 se mantuvo dentro de rangos normales, y alcanzó hasta 320 ñ 57 mmHg con la hiperventilación. Las alteraciones gasométricas en perros Beagle, entre 6 y 9 kg de PC, durante neumoperitoneo con CO2 (8 mmHg), son similarea a las observadas en animales de mayor talla. Estas pueden ser controladas modificando la frecuencia ventilatoria