The effects of mild hypothermia on coagulation tests and haemodynamic variables in anaesthetized rabbits / Efectos de la hipotermia leve sobre las pruebas de coagulación y las variables hemodinámicas en conejos anestesiados

OBJECTIVE: Hypothermia has been associated with coagulation defects. The purpose of this experimental study was to investigate the effect of mild hypothermia on clinically used coagulation tests and on haemodynamic variables. METHODS: Νine New Zealand rabbits were subjected to mild core hypothermia by administration of general anaesthesia and exposure to room temperature of 22°C for 60 minutes. Blood samples were obtained at normothermia and mild hypothermia for measurement of prothrombin time, activated partial thromboplastin time, fibrinogen levels, platelet count and haemoglobin concentration. Hypothermic values were compared to the normothermic values. Additionally, the progressive temperature drop and haemodynamic changes (blood pressure, heart rate) were recorded. RESULTS: Core temperature decreased significantly over time changing from 39.4 ± 0.27 to 36.6 ± 0.28°C (p = 0.0001). Prothrombin time and activated partial thromboplastin time decreased at hypothermia, but the changes were not statistically significant (p = 0.203 and p = 0.109, respectively). Platelet count, fibrinogen levels and haemoglobin concentration decreased significantly (p = 0.0001, p = 0.03 and p = 0.027) but remained within normal limits. Mean arterial pressure and heart rate declined significantly over time (p = 0.0001 and p = 0.0001, respectively). CONCLUSION: The results of this study suggest that short term mild hypothermia may affect the coagulation mechanism to a clinically nonsignificant extent, while haemodynamic responses are significantly suppressed.

OBJETIVO: La hipotermia ha sido asociada con defectos de coagulación. El propósito de este estudio experimental fue investigar el efecto de la hipotermia leve sobre las pruebas de coagulación de uso clínico, así como sobre las variables hemodinámicas. MÉTODOS: Nueve conejos de Nueva Zelanda fueron sometidos a hipotermia central leve mediante la administración de anestesia general y exposición a una temperatura ambiente de 22°C durante 60 minutos. Se obtuvieron muestras de sangre en condiciones de normotermia e hipotermia leve para medir el tiempo de protrombina, el tiempo de tromboplastina parcial activada, los niveles de fibrinógeno, el conteo de plaquetas, y la concentración de hemoglobina. Se compararon los valores hipotérmicos con los valores normotérmicos. Además, se registraron la caída progresiva de la temperatura y los cambios hemodinámicos (presión sanguínea, frecuencia cardíaca). RESULTADOS: La temperatura corporal central disminuyó significativamente con el tiempo, cambiando de 39.4 ± 0.27 a 36.6 ± 0.28°C (p = 0.0001). El tiempo de protrombina y el tiempo de tromboplastina parcial activado disminuyeron en la hipotermia, pero los cambios no fueron estadísticamente significativos (p = 0.203 y p = 0.109, respectivamente). El conteo de plaquetas, los niveles de fibrinógeno y la concentración de la hemoglobina disminuyeron significativamente (p = 0.0001, p = 0.03 y p = 0.027) pero permanecieron dentro de los límites normales. La presión arterial promedio y la frecuencia cardíaca disminuyeron significativamente con el tiempo (p = 0.0001 y p = 0.0001, respectivamente). CONCLUSIÓN: Los resultados de este estudio sugieren que la hipotermia leve a corto plazo puede afectar el mecanismo de la coagulación hasta un punto clínicamente no significativo, mientras que respuestas hemodinámicas se suprimen significativamente.

Improvement of skin-graft survival after autologous transplantation of adipose-derived stem cells in rats.

BACKGROUND: Skin grafts are frequently used for a variety of indications in plastic and reconstructive surgery. Their necrosis is a common complication, while different therapies have been proposed. Currently, adipose-derived stem cells (ASCs) hold great promise for their angiogenic potential and role during tissue repair. In this study, autologous transplantation of ASCs was used in skin grafts in rats to determine if it increases angiogenesis, skin-graft survival and wound healing. METHODS: ASCs were isolated, cultured, labelled with fluorescent dye and injected under full-thickness skin grafts in 10 rats (group 1), while 10 others served as controls (group 2). Skin grafts were analysed after 1 week. Collagen's framework was assessed with Masson's trichrome stain and angiogenesis with von Willebrand factor (vWF) immunohistochemistry. In addition, immunohistochemical staining intensity of vascular endothelial growth factor (VEGF) and transforming growth factor b3 (TGFb3) was assessed in all grafts. RESULTS: Mean area of graft necrosis was significantly less in group 1 than in group 2 (6.12% vs. 32.62%, p<0.01). Statistically significant increase of microvessel density, collagen density, VEGF and TGFb3 expression was noted in group 1 compared with group 2 (all: p<0.01). CONCLUSIONS: These findings suggest that autologous ASCs transplantation increases full-thickness skin-graft survival and shows promise for use in skin-graft surgery. This might be both due to in situ differentiation of ASCs into endothelial cells and increased secretion by ASCs of growth factors, such as VEGF and TGFb3 that enhance angiogenesis and wound healing.

Malignant pleural effusion and talc pleurodesis. Experimental model regarding early kinetics of talc particle dissemination in the chest after experimental talc pleurodesis.

PURPOSE: Talc remains a commonly used agent for pleurodesis malignant pleural effusion. Nevertheless, it is associated with a 3-9% incidence of pulmonary reactions ranging from simple pneumonitis to acute respiratory distress syndrome (ARDS). The underlying lung pathology and the size and rate of talc particle dissemination have been implicated as the cause of these complications. There seems to be an acknowledged lack of evidence regarding detailed very early intrathoracic talc particle migration. MATERIALS AND METHODS: Thirty white male New Zealand rabbits underwent experimental pleurodesis and were randomly assigned to 3 (A, B, C) study groups (10 in each group). Rabbits were sacrificed 6, 12 and 18 h after talc administration. Samples from both lungs, mediastinum and parietal pleura were obtained. The number of talc crystals (m) deposited was counted and averaged along all slices of the various tissue samples. RESULTS: A high degree of early talc deposition and subsequent epithelial injury in all examined tissues was observed. Diffuse talc deposition occurred in both lungs, but in a different manner. On the side of talc administration, talc particles were deposited in a time-dependent fashion. On the contralateral side, talc was rapidly deposited during the first hours after the procedure, then the rate of deposition decreased, and increased again between 12 and 18 h after the procedure. CONCLUSION: Large-sized talc particles are deposited on both lungs very early after pleurodesis. At the same time inflammatory pulmonary changes appear bilaterally. Despite contradicting data in the literature, these findings should always be kept in mind when performing this procedure in high risk patients.

Diabetes may increase risk for oral cancer through the insulin receptor substrate-1 and focal adhesion kinase pathway.

In light of recent epidemiological studies that associate diabetes mellitus with increased risk for oral cancer, we investigated in diabetic (type I) and normal rats with induced oral squamous cell carcinoma whether the molecular basis for that putative association involves insulin receptor substrate-1 (IRS-1) and focal adhesion kinase (FAK). Fourteen diabetic and 12 normal rats developed cancer after 4-nitroquinoline-N-oxide treatment, while six diabetic and six normal animals were used as controls. Oral sections were studied using monoclonal antibodies against IRS-1 and FAK proteins. Expression of IRS-1 was significantly higher in diabetic than normal rats, but it decreased in diabetic animals with tumor, especially in more advanced stages. FAK expression was significantly higher in rats with cancer in comparison to the ones without it, regardless the diabetes status. These data suggest that the IRS-1/FAK pathway is altered by diabetes resulting in reduced cell adhesion and possibly increasing risk for oral cancer.

Cell proliferation and apoptosis culminate in early stages of oral oncogenesis.

Markers of cell proliferation (Ki-67 antigen) and apoptosis (Bax, Bcl-2) were studied in an experimental system of induced oral carcinogenesis in Syrian golden hamsters. Thirty-seven animals were divided into one control group and three experimental groups, which were treated with a carcinogen and sacrificed at 10, 14 and 19 weeks after treatment. The histological status of the lesions in the three experimental groups corresponded well with tumour advancement (from oral mucosal dysplasia to moderately differentiated squamous cell carcinoma). Tumour sections were studied using monoclonal antibodies against Bax, Bcl-2 and Ki-67 proteins. Pro-apoptotic Bax expression maintained high levels during all stages of oral carcinogenesis. Anti-apoptotic Bcl-2 expression decreased significantly in dysplastic and early invasion lesions and consequently increased almost to normal tissue level in consequent stages. Finally, Ki-67 expression increased sharply in initial stages of oral carcinogenesis, but significantly decreased in later stages.

Rapid alterations of serum oxidant and antioxidant status with the intravenous administration of n-6 polyunsaturated fatty acids.

In an attempt to achieve the safe intravenous administration of two n-6 polyunsaturated fatty acids (PUFAs), gamma-linolenic acid (GLA) and arachidonic acid (AA), and to study the subsequent changes on the total oxidant and antioxidant status, various steadily increasing doses of each acid were injected intravenously at different infusion times in 28 male rabbits. Blood samples were collected at 15-min time intervals by the hepatic veins and from the carotid artery; oxidant status was determined by the thiobarbiturate assay and total antioxidant status (TAS) was assessed by a colorimetric assay. Both n-6 PUFAs were administered with safety at a dose of 25 mg/kg within 10 min accompanied by an increase of malonodialdehyde concentrations in the hepatic veins and in the carotid artery 30-45 min, respectively, after the end of the infusion of GLA and/or AA. Similar changes did not occur in red cell membranes after the infusion of AA. TAS presented reciprocal changes to malonodialdehyde production; the main consumption of TAS was observed in all samples 30-60 min after the end of the infusion of n-6 PUFAs. The above-mentioned rapid alterations occurring in both serum oxidant and antioxidant status after GLA might have a future clinical therapeutic significance in conditions like cancer and disseminated infectious diseases.

[Changes in tissue enzymes during "in situ" renal ischemia with or without protection of the kidneys]. / Etude des variations des enzymes tissulaires au cours de l'ischémie rénale "in situ" associée ou non à des méthodes de protection du rein.

Three methods of preservation of the in situ temporarily ischaemic kidney were compared in dogs. The study was carried out in 24 dogs, divided in 4 groups. Each group included 4 dogs in which the ischaemic time was 60 minutes, and 3 dogs in which the ischaemic time was 90 minutes. The experimental animals of the first group served as controls (warm ischaemia); in the second group renal hypothermia was accomplished by an arterial infusion of Collins' solution at 4 degrees C; in the third group preservation of the kidney was attempted only by an arterial infusion of inosine (90-120 mg/kg); finally in the fourth group, the infusion of Collins' solution was combined with infusion of inosine (800-1 000 mg/l Collins' solution). The assessment of the damage of the ischaemic kidney was made by histo-enzymological analysis of renal tissue specimens received from each animal just before initiation of the ischaemia and on the 21st post-operative days. The enzymes examined in this analysis were: Alkaline Phosphatase, ATP-ase, Glutamate Dehydrogenase, Glucose-6-phosphatase, Hydroxybutyrate Dehydrogenase and gamma-GT. These studies have shown that the ischaemic kidney is best preserved by the arterial infusion of Collins' solution with simultaneous infusion of inosine.