Martin Santos

Functional recovery of chronic paraplegic pigs after autologous transplantation of bone marrow stromal cells.

Background. Bone marrow stromal cells (BMSC) transplantation offers promise in the treatment of chronic paraplegia in rodents. Here, we report the effect of this cell therapy in adult pigs suffering chronic paraplegia. Methods. Three months after spinal cord injury, autologous BMSC in autologous plasma was injected into lesion zone and adjacent subarachnoid space in seven paraplegic pigs. On the contrary, three paraplegic pigs only received autologous plasma. Functional outcome was measured weekly until the end of the follow-up, 3 months later. Results. Our present study showed progressive functional recovery in transplanted pigs. At this time, intramedullary postraumatic cavities were filled by a neoformed tissue containing several axons, together with BMSC that expressed neuronal or glial markers. Furthermore, in the treated animals, electrophysiological studies showed recovery of the previously abolished somatosensory-evoked potentials. Conclusions. These findings confirm previous observations in rodents and support the possible utility of BMSC transplantation in humans suffering chronic paraplegia.

Effects of alpha-2 adrenoceptor agonists during recovery from isoflurane anaesthesia in horses.

REASONS FOR PERFORMING STUDY Recovery from inhalant anaesthesia in the horse is a critical and difficult period to manage; however, several factors could help to obtain a calm recovery period including choice of anaesthetic and analgesic procedure used and the conditions under which anaesthetic maintenance and recovery occur. OBJECTIVES The objective of this study was to evaluate and compare the quality of recovery in horses administered saline, xylazine, detomidine or romifidine during recovery from isoflurane anaesthesia. METHODS Six mature and healthy horses were premedicated with i.v. xylazine and butorphanol, and anaesthesia induced using ketamine. After 2 h of inhalant anaesthesia with isoflurane vaporised in oxygen, saline solution, xylazine (0.1 mg/kg bwt), detomidine (2 microg/kg bwt) or romifidine (8 pg/kg bwt) were administered. The quality of recovery of each horse and the degree of sedation and ataxia were evaluated. Cardiovascular and respiratory parameters were recorded, and arterial blood samples obtained and analysed for pH, PO2 and PCO2 during recovery. RESULTS Quality of recovery was better in groups treated with alpha-2 adrenergic receptors agonists, showing less ataxia. Degree of sedation was greater in the romifidine group. CONCLUSIONS We concluded that the administration of alpha-2 adrenoceptor agonists during recovery from isoflurane anaesthesia in horses prolonged and improved the quality of recovery without producing significant cardiorespiratory effects. POTENTIAL CLINICAL RELEVANCE Administration of alpha-2 adrenoceptor agonists after inhalent anaesthesia could prevent complications during the recovery period.

Optical aggregometry versus the PFA–100™: experimental studies in pigs treated with propofol

An experimental study of platelet aggregation was performed in 22 male Landrace 2 Large-White crossbred pigs treated with propofol at different doses, to compare the results of optical aggregometry with those of the PFA-100™ (Dade Int., Miami, FL, USA), a new platelet function analyzer. Platelet aggregation was analyzed in basal blood samples by both methods, after which the pigs were divided into three groups: G1, anaesthetic induction with propofol (2 mg/kg intravenously (i.v.)); G2, anaesthetic induction with propofol (2 mg/kg i.v.), followed by a second dose of 1.5 mg/kg; and G3, anaesthetic induction with propofol (2 mg/kg i.v.), followed by 1 h of continuous i.v. infusion at 13 mg/kg/h. Four minutes after propofol injection, blood samples were again taken from each group and studied by both methods. In groups G2 and G3, both methods showed reduced platelet aggregation, while in group G1 neither evidenced an anti-aggregating effect of propofol. Under our experimental conditions: (1) the propofol effect on platelet aggregation depends on the plasma concentration; (2) the results obtained with the two methods are comparable; (3) PFA-100™ may provide an alternative to optical aggregometry for detecting the effects of anaesthetic agents ex vivo .

Aspirin synergistically potentiates isoflurane minimum alveolar concentration reduction produced by morphine in the rat.

Background The combination of opioids and nonsteroidal antiinflammatory drugs is more analgesic than the summed effect of each drug administered separately. This synergism has been used to obtain analgesia in the postoperative period at doses at which side effects are minimal. The aim of this study is to evaluate the analgesic interaction between aspirin and morphine in the rat during isoflurane anesthesia. The reduction in minimum alveolar concentration of isoflurane (MACISO) was used as an objective measure of the analgesic potency of individual drugs and their use in combination. Methods Thirty‐seven male Wistar rats were anesthetized with isoflurane in oxygen, and the MACISO was determined before and after the intravenous administration of aspirin and morphine. Rats were administered morphine alone (1, 3, and 10 mg/kg) or morphine (1 and 3 mg/kg) and aspirin (30 mg/kg). The MACISO was determined from alveolar gas samples at the time of tail clamp. The duration of MACISO reduction was recorded. Results Aspirin did not have an effect on MACISO, (average, 1.35 +/− 0.1%), whereas the combination of morphine (1 and 3 mg/kg) and aspirin (30 mg/kg) produced a reduction in the dose of morphine needed to produce the same degree of MACISO reduction. Actual MACISO+drug data were as follows: 1 mg/kg morphine, 1.17 +/− 0.14%; 3 mg/kg morphine, 0.98 +/− 0.15%; 1 mg/kg morphine plus aspirin, 0.90 +/− 0.04%; 10 mg/kg morphine, 0.63 +/− 0.13%; and 3 mg/kg morphine plus aspirin, 0.64 +/− 0.06%. Conclusions The synergistic effects of aspirin and morphine allow a clinically significant reduction in the requirements of isoflurane and isoflurane plus morphine, and these drug combinations may decrease the side effects associated with the use of single higher, equianalgesic doses of these drugs.

Meloxicam, a specific COX-2 inhibitor, does not enhance the isoflurane minimum alveolar concentration reduction produced by morphine in the rat.

A synergistic effect of nonselective cyclooxygenase (COX) inhibitors on morphine-induced decrease of isoflurane minimum alveolar concentration (MACISO) has been observed in the rat. We studied the influence of specific COX-2 inhibitors on this decrease of MAC. Sixty-four female rats were anesthetized with isoflurane in oxygen. The animals were grouped into saline solution, aspirin (30 mg/kg), morphine (1 mg/kg), morphine (1 mg/kg) + aspirin (30 mg/kg), meloxicam (1 and 3 mg/kg), and morphine (1 mg/kg) + meloxicam (1 and 3 mg/kg). Then the MACISO was determined from alveolar gas samples at the time of tail clamp. The groups treated with saline solution, aspirin, and 1 and 3 mg/kg meloxicam did not express any statistically relevant changes among them. The administration of morphine + meloxicam 1 or 3 mg/kg significantly reduced the MACISO just as in the group where only morphine was administered (morphine 1.35% ± 0.07%, morphine + 1 mg/kg meloxicam 1.36% ± 0.04%, and morphine + 3 mg/kg meloxicam 1.37% ± 0.08%). The greatest reduction of MACISO was after administration of morphine + aspirin (1.19% ± 0.05%). The administration of meloxicam does not potentiate the morphine-induced decrease of MACISO in the rat.

Stem cells and bronchial stump healing

OBJECTIVE Bronchial stump dehiscence is still the most feared complication for the thoracic surgeon, with mortality rates ranging from 25% to 75%. This study reports the histologic effect of adult stem cells in the healing process of the bronchial stump after lung resection. METHODS A left pneumonectomy was performed in 36 Wistar rats. Half of them received previously labeled bone marrow-derived stem cells applied to the bronchial stump. In each group, 7 rats were sacrificed on day 7 and 11 rats were sacrificed on day 21. Macroscopic variables and histopathologic features were analyzed. RESULTS On days 7 and 21, there were fewer adhesions in the stem cell group (P = .042 and .031, respectively). Bronchial stump restitutio ad integrum on day 21 was found predominantly in rats from the stem cell group (P = .012). At that time, the same group showed significantly less inflammation in every layer of the stump (P < .050). CONCLUSIONS Bone marrow-derived stem cells administered topically on a bronchial stump are able to migrate, reach the bronchial wall, and participate in the healing process. This induces fewer adhesions, less inflammatory response, and better regeneration of the tissue.

Beneficial effects of synthetic KL4­surfactant in experimental lung transplantation

The aim of this study was to investigate whether intratracheal administration of a new synthetic surfactant that includes the cationic, hydrophobic 21-residue peptide KLLLLKLLLLKLLLLKLLLLK (KL4), might be effective in reducing ischaemia–reperfusion injury after lung transplantation. Single left lung transplantation was performed in Landrace pigs 22 h post-harvest. KL4 surfactant at a dose of 25 mg total phospholipid·kg body weight−1 (2.5 mL·kg body weight−1) was instilled at 37°C to the donor left lung (n = 8) prior to explantation. Saline (2.5 mL·kg body weight−1; 37°C) was instilled into the donor left lung of the untreated group (n = 6). Lung function in recipients was measured during 2 h of reperfusion. Recipient left lung bronchoalveolar lavage (BAL) provided native cytometric, inflammatory marker and surfactant data. KL4 surfactant treatment recovered oxygen levels in the recipient blood (mean±sd arterial oxygen tension/inspiratory oxygen fraction 424±60 versus 263±101 mmHg in untreated group; p=0.01) and normalised alveolar–arterial oxygen tension difference. Surfactant biophysical function was also recovered in KL4 surfactant-treated lungs. This was associated with decreased C-reactive protein levels in BAL, and recovery of surfactant protein A content, normalised protein/phospholipid ratios, and lower levels of both lipid peroxides and protein carbonyls in large surfactant aggregates. These findings suggest an important protective role for KL4 surfactant treatment in lung transplantation.

Heterotopic tracheal transplantation animal model of bronchiolitis obliterans: a reproducible model.

BACKGROUND Chronic rejection or bronchiolitis obliterans (BO) is the main cause of morbidity and mortality 1 year after lung transplantation. The objective of this study was to develop a reproducible animal model that mimics the typical histological findings in human BO after lung transplantation. MATERIAL AND METHODS We used 2 rat strains - Lewis (L) and Wistar (W) - and transplanted a segment of donor trachea into each recipient. The animals were divided into 2 groups: 1) donor and recipient of the same strain (W-W), and 2) donor and recipient of different strains (L-W). From each group, we created 4 subgroups examined at different time-points after transplantation (7, 14, 21, and 28 days). Variables were: degree of narrowing of the tracheal lumen, histological findings classified into 1 of 5 patterns, location of the ink (green or black), and presence of foreign body granuloma. RESULTS In the W-W group, we observed a gradual onset of fibrosis, notable at 21 and 28 days post-implant. In the L-W group, obliteration of the tracheal lumen was observed in all animals, with acute inflammation by day 7, and fibrosis from then on, loose fibrosis by day 14, and frank fibrosis on days 21 and 28. Green ink was observed in vascular structures, located in granulation tissue in the early phases of the BO-type lesion, then the staining becoming less clear as the histological features developed towards frank fibrosis. This trend was seen in both groups. CONCLUSIONS The obliteration and fibrosis are more extensive if the donor and recipient are from different strains (L-W). Histological findings in the L-W group corresponded to progressive fibrosis until day 21.