Rigid bronchoscopy induces bacterial translocation: an experimental study in rats.

Bronchoscopy has the potential to propagate infections. Bacterial translocation was hypothesised to be the cause of infections observed following bronchoscopy and this study was designed to assess the risk of bacterial translocation following rigid bronchoscopy in rats. A total of 30 rats were evaluated. The study group (n=15) underwent rigid bronchoscopy. Arterial blood gas analysis was performed in all rats. Blood and tissue cultures from the ileum, caecum, mesenteric lymph nodes, liver, spleen, mediastinal lymph nodes and lung were obtained 24 h following bronchoscopy. Bacterial translocation to the mesenteric lymph nodes was found in seven of 15 rats (46.7%) that underwent bronchoscopy, compared with none of the controls. Of the seven positives, three rats (42.8%) also demonstrated other organ involvement, such as the liver and spleen. Escherichia coli, Salmonella typhymirium, S. enteritidis and Pseudomonas spp. were found as translocating bacteria. In the study group, pH and arterial oxygen tension were significantly lower and arterial carbon dioxide tension was higher, compared with controls. This study shows that rigid bronchoscopy may induce bacterial translocation in rats. Further investigations aimed at understanding the clinical consequences of this phenomenon are warranted.     

Achieving efficient anti-adhesion in re-mediastinoscopy: an experimental study in rats

OBJECTIVE: Re-mediastinoscopy can be a difficult procedure due to fibrosis in the mediastinum. We have investigated the effect of an anti-adhesive barrier agent "hylan B gel" on the formation of adhesions after dissection in the superior mediastinum in a rat model. METHODS: The study was conducted in 70 male Sprague-Dawley rats weighing 300 g. The strap muscles were divided by a midline cervical incision. The anterior and lateral aspects of the trachea were dissected to the level of the carina. Hylan B gel (Sepragel Sinus, Genzyme Company, Redgefield, NJ, USA) was used to create an anti-adhesive barrier. The rats who were subjected to surgery were sacrificed on postoperative days 14 and 28. All rats were previously divided into 5 groups: Sham group (n = 10); Group 1 (n = 15) surgery alone, sacrificed on day 14; Group 2 (n = 15) surgery and Sepragel, sacrificed on day 14; Group 3 (n = 15) surgery alone, sacrificed on day 28; Group 4 (n = 15) surgery and Sepragel, sacrificed on day 28. Histopathological analysis was performed to study the effect of the anti-adhesive agent. Scores were calculated based on collagen fibrosis, fibroblasts, granulation tissue, muscle alterations/inflammation, histiocytes, mononuclear giant cells, inflammation and vascular proliferation. RESULTS: Collagen fibrosis and fibroblast scores, which represent adhesions, were significantly higher in Groups 1, 2, 3, 4 than in the Sham group ( P < 0.01). The degree of adhesions on day 14 was found to be higher in Group 1 compared to Group 2 ( P < 0.01). Adhesions on day 28 were higher in Group 3 compared to Group 4 ( P < 0.01). There were no differences between groups with regard to foreign body reactions ( P > 0.05). CONCLUSION: Adhesions causing technical difficulty during re-mediastinoscopy can be reduced by the application of anti-adhesive agents during the primary procedure.     

Ultrasonic clot disruption: an in vitro study

We studied in vitro the efficacy of ultrasound in human blood clot disruption, as well as the effects of clot age, wire probe length, and streptokinase on the outcome. The study included sizing the resulting particulate debris. Clot age (1 to 7 days) had no effect on the time required for disruption. Three groups of 1-day-old clots (n = 10 for each) were exposed to the same ultrasonic power source via probes of different lengths. The time required for clot disruption varied approximately as the square of the length for probes of 31, 56, and 105 cm, but was less than 3 minutes even for the longest probe employed. Disrupted whole-blood clot as well as cell-free fibrin clot solutions were analyzed for particulates by the resistive-pulse technique (size range: 2.5 to 80 microns). Debris as large as 80 microns were seen after disruption of whole blood clots, while cell-free fibrin clots contributed little above 40 microns. In all size ranges, whole blood clots produced two orders of magnitude more particulates than cell-free fibrin clots. Addition of streptokinase (7500 U/mL) had little effect on the size distribution of debris, with 99% of all particulates being smaller than 10 microns. D-dimer analysis was performed on the dissolved cell-free fibrin clots with and without streptokinase. While the former had analytically higher D-dimer concentrations than the latter (from eight- to 16-fold), the levels in both cases would be below detectability if measured in vivo. Hence the present study supports the concept that ultrasound can be employed to disrupt human blood clots by mechanisms (mechanical and cavitational) other than fibrinolysis.     

早期慢性肾脏疾病心脏病变的实验研究

目的研究早期慢性肾脏疾病大鼠心脏病变情况。方法通过减少肾脏切除量和缩短喂养时间方法建立早期慢性肾脏疾病大鼠动物模型,分析其心脏病变,包括心脏重,体重比值、心肌细胞增大、心肌间质纤维化程度和心肌间质I型、Ⅲ型胶原含量等。结果（1）实验组大鼠血尿素氮水平、尿白蛋白/肌酐比值、肾小球系膜增生程度均高于对照组,但实验组和对照组之间血肌酐水平差异无统计学意义,且病理改变较轻,表明早期CKD模型制作是成功的。（2）实验组大鼠心脏重,体重比值高于对照组（P〈0.01）,心肌细胞肥大,心肌间质纤维化明显。免疫组化测定显示心肌组织内I型和Ⅲ型胶原量均高于对照组（P均〈0.01）。结论心脏病变在早期CKD大鼠动物模型中即已经存在。表现为重量增加、间质纤维化、胶原增多等。     

The influence of chronic pancreatitis on carcinogenesis: an experimental study in rats

BACKGROUND: The literature contains many controversial or unclearly defined opinions about the risk of development of carcinoma of the exocrine part of the pancreas in patients with chronic pancreatitis. This and our own clinical observations based on analysis of patients with chronic pancreatitis treated surgically (anastomotic and resectional procedures) formed the background to an experimental study to define the risk of carcinogenesis in the course of chronic pancreatitis in rats. EXPERIMENTAL FINDINGS: In Wistar rats with chronic pancreatitis induced by etionine and then exposed to carcinogenic action of azaserine, proliferation, adenomas and acinic cell carcinomas of the exocrine part of the pancreas were diagnosed; the carcinomas were transplantable. In rats treated with azaserine only, benign proliferative lesions and adenomas were found. The presence of the p53 mutation protein was observed in carcinomatous pancreatic cells in malignant lesions of the pancreas in primary and transplantable cancers, but was not detected in benign proliferative lesions and adenomas. Chronic pancreatitis in Wistar rats predisposes the exocrine part of pancreas to malignant transformation. Growth of cancers of the exocrine part of the pancreas in male rats, but not in female rats, suggests hormonal determination of experimental pancreatic cancer. CONCLUSIONS: Results demonstrate that chronic pancreatitis in rats predisposes to malignant proliferative lesions, including acinic cell carcinoma. Expression of the protein product of p53 gene mutations correlated with neoplastic transformation of pancreas preceded by chronic pancreatitis, and was also detected in transplantable tumours.     

Distribution of calibrated talc after intrapleural administration: an experimental study in rats

STUDY OBJECTIVE: Many reports have shown that talc is the most effective and least expensive agent for the creation of a pleural symphysis. However, its use still remains controversial due to severe acute respiratory side effects possibly related to the systemic dissemination of talc particles. The purpose of this study was to assess the distribution of calibrated talc after intrapleural administration in rats. MATERIAL AMD METHODS: Thirty-seven Wistar male rats were randomly assigned to undergo pleurodesis by talc slurry (33 rats) or by simple chest tube drainage (control group; 4 rats). Forty milligrams of calibrated talc suspended in 1 mL sterile saline solution was injected into rats in the treated group. The animals were randomly assigned for autopsy at 24 or 72 h after pleural injection. Lungs, parietal pleura, diaphragm, liver, kidneys, spleen, pericardium, brain, and blood were assessed by polarized light for birefringent talc particle detection and counting. RESULTS: No deaths were observed. The autopsies showed no pleurodesis at 24 and 72 h. Despite high doses of talc (extrapolated from the dose of 10 g in a 70-kg adult man), few talc particles were found in the liver of two rats, in the spleen of one rat, and only one particle of talc was observed at the brain surface of the rat studied by scanning electron microscopy. No particles were found in the other organs, in particular in the contralateral lung and blood, contrasting with previously published results using noncalibrated talc particles. CONCLUSIONS: The lack of systemic dispersion of talc particles, with the packaging talc we currently use in our clinical practice, is probably due to the size of the talc particles, which are larger than the other talc preparations. Calibrated talc is required in case of intrapleural administration for pleurodesis to avoid systemic dissemination and potential secondary acute respiratory failures.     

Attitude change in older age: an experimental study.

The role of age in the attitude change process was experimentally studied by exposing older (Mean age: 77.5 years) and younger (Mean age: 19.7 years) women to persuasive information presented at different speeds. In general, the higher speed levels which were employed to decrease information reception resulted in less attitude change, but no overall age differences in the amount of attitude change were observed. In fact, the older women changed their attitudes somewhat more than the younger ones in the normal speed condition. Two mediating processes--positive evaluation and information reception--seemed to counteract each other in producing attitude change in the two age groups: the older women reacted more positively toward the presentation than the younger women, but they understood less of the presented information.     

Phasic study of intestinal homeostasis disruption in experimental intestinal obstruction

AIM: To investigate the phasic alteration of intestinal homeostasis in an experimental model of intestinal obstruction.METHODS: A rabbit model of intestinal obstruction was established by transforming parts of an infusion set into an in vivo pulled-type locking clamp and creating a uniform controllable loop obstruction in the mesenteric non-avascular zone 8 cm from the distal end of the ileum. The phasic alteration of intestinal homeostasis was studied after intestinal obstruction. The changes in goblet cells, intraepithelial lymphocytes, lamina propria lymphocytes, and intestinal epithelium were quantified from periodic acid-Schiff-stained sections. Ornithine decarboxylase (ODC) activity and serum citrulline levels were measured by high-performance liquid chromatography. Claudin 1 mRNA expression was examined by real-time polymerase chain reaction analysis. Intestinal microorganisms, wet/dry weight ratios, pH values, and endotoxin levels were determined at multiple points after intestinal obstruction. Furthermore, the number and ratio of CD3⁺, CD4⁺ and CD8⁺ T cells were determined by flow cytometry, and secretory IgA levels were measured with an enzyme-linked immunosorbent assay.RESULTS: A suitable controllable rabbit model of intestinal obstruction was established. Intestinal obstruction induced goblet cell damage and reduced cell number. Further indicators of epithelial cell damage were observed as reduced serum citrulline levels and claudin 1 gene expression, and a transient increase in ODC activity. In addition, the wet/dry weight ratio and pH of the intestinal lumen were also dramatically altered. The ratio of Bacillus bifidus and enterobacteria was reversed following intestinal obstruction. The number and area of Peyer’s patches first increased then sharply decreased after the intestinal obstruction, along with an alteration in the ratio of CD4/CD8⁺ T cells, driven by an increase in CD3⁺ and CD8⁺ T cells and a decrease in CD4⁺ T cells. The number of lamina propria lymphocytes also gradually decreased with prolonged obstruction.CONCLUSION: Intestinal obstruction can induce disruption of intestinal homeostasis.     

Effect of blockade of transdiaphragmatic absorption of bacteria on survival in peritonitis: an experimental study in rats.

An experimental rat model of established peritonitis was used to test the effect of intraperitoneal injection of platelet rich plasma (PRP) on blood and peritoneal fluid culture positivity and survival rates. Thirty animals divided into two groups of 15 each were studied. The first group served as control while animals in the second group received intraperitoneal injection of PRP. The use of PRP in established. Peritonitis was of no significant benefit.     

Intestinal anastomotic healing in the absence of suture material: an experimental study in rats

In order to investigate the influence of sutures on intestinal anastomotic healing, 48 rats underwent both ileal and colonic resection. In 24 rats all intestinal sutures were removed 30 min after anastomotic construction (group 1), while in the remaining animals (group 2) the sutures were left in place. Bursting pressures and collagen (hydroxyproline) levels in anastomotic segments were measured 1, 3, and 7 days after operation. Two lethal ileal dehiscences and 9 anastomotic abscesses (5 ileal and 4 colonic) occurred in group 1, while in group 2 there were 3 ileal anastomotic abscesses. On the first day after operation, bursting pressures were significantly lower in sutureless ileal and colonic than in sutured anastomoses. During the post-operative course, changes in collagen concentrations in ileal and colonic segments did not differ between the groups. Thus, sutures are only essential in providing anastomotic strength during the immediate post-operative period, but do not seem to affect post-operative collagen metabolism.

---

Résumé Dans le but d'étudier l'influence des sutures sur la cicatrisation des anastomoses intestinales, 48 rats ont subi une résection à la fois iléale et colique. 24 rats ont eu une résection de leur suture intestinale 30 minutes après la réalisation de l'anastomose, tandis que chez les animaux restants les sutures étaient laissé en place. 3 à 7 jours après l'opération la pression de rupture et les taux de collagène dans les segments anastomotiques ont été mesurés. Des fistules iléales mortelles et 9 abcés anastomotiques (5 iléaux et 4 coliques) sont survenus dans le groupe expimental contre trois abcés anastomotiques dans le groupe de contrôle. La pression de rupture était significativement plus basse au niveau des anastomoses à la fois iléales et coliques sans suture mais seulement le premier jour après l'opération. Les modifications postopératoires des concentrations de collagène dans les segments iléaux ou coliques ne différaient pas entre les deux groupes. Ainsi les sutures ont seulement un rôle essentiel en renforçant l'anastomose durant la période post-opératoire tout à fait initiale mais ne semblent pas affecter le métabolisme post-opératoire du collagène.

     

大鼠脑出血后血肿周围微血管变化的研究

目的 对大鼠脑出血后血肿清除前后血肿周围组织内微血管的病理学变化进行初步研究.方法 雄性SD大鼠36只,采用配伍组设计,分为血肿组、血肿清除组和假手术组.每组12只大鼠,每组中各有1只大鼠取自同一窝别,体重相似.采用大鼠尾状核注射自体凝固动脉血法制作脑出血模型.血肿清除组大鼠术后30min注入尿激酶清除血肿.术后6 h用墨汁-右旋糖酐溶液于升主动脉灌注脑组织.用MIAS2000图像分析系统测定大鼠紧邻血肿部位1 mm2区域组织内的平均微血管直径,计算微血管密度指数.结果 血肿组血肿周围组织内微血管数目明显减少,微血管断裂、僵直、变细、血流淤滞.早期血肿清除后血肿周围组织内微血管数目大致恢复正常,微血管变细、僵直及墨汁浓集现象基本消失.血肿组、血肿清除组、假手术组血肿周围微血管平均直径分别为(10.4±2.4)、(19.8±2.0)、(19.6±1.7)μm;微血管密度指数为0.025±0.007、0.264±0.044、0.214±0.020.血肿组与血肿清除组及假手术组平均直径比较,差异均有统计学意义(P＜0.01);血肿清除组与假手数组间差异无统计学意义.血肿组平均微血管密度指数与血肿清除组及假手术组差异均有统计学意义(P＜0.01).结论 血肿周围组织内存在微循环障碍.超早期血肿清除可明显改善血肿周围组织的微循环状态.     

Ossification in cancer of the stomach: an experimental study.

In rats with Nitrosoguanidine induced carcinomas of the gastric stump, heterotopic ossifications are found freqently. The following stages of differentiation during the desmal ossification in the stump carcinomas are demonstrated: 1. Osteoblasts, 2. Osteoid, 3. Woven bone, 4. Lamellar bone. --The islands of metaplastic bone cells are predominantly located in the invasive marginal zone of the carcinoma of the gastric stump. The histology of the heterotopic ossification in the gastric stump of the rat is similar to that one seen in stomach cancer of men. The model here described seems to be suitable for further study of metaplastic bone formation in the gastrointestinal tract.     

Bioprosthetic tissue calcification: influence of blood contact and arterial pressure. an experimental study in rats and sheep

BACKGROUND AND AIM OF THE STUDY: Several animal models are currently used to study bioprosthetic tissue calcification. The study aim was to evaluate the influence of species and environmental factors (blood contact and arterial pressure) on valve tissue mineralization. METHODS: Glutaraldehyde-fixed porcine cusps and aortic wall samples were implanted subcutaneously in rats (n = 6) and sheep (n = 18). In sheep, similar samples were also implanted into the jugular vein (blood contact) and carotid artery (blood contact and arterial pressure). Tissue was explanted at intervals up to three months and evaluated macroscopically, and by X-radiography, light and electron microscopy and calcium content measurement. RESULTS: After eight weeks in the subcutaneous position, glutaraldehyde-fixed cusps were severely calcified in rats, but not in sheep (78.6 +/- 28.3 and 0.3 +/- 0.5 microg Ca/mg, respectively; p <0.001). Aortic wall samples were calcified in both species, but less in sheep (p <0.001). In sheep, blood contact without arterial pressure (venous implants) significantly increased the calcification of cusp and even more of aortic wall tissue. Arterial pressure had no effect on calcification of aortic wall tissue. CONCLUSION: Major inter-species inconsistencies were found in valve tissue calcification after subcutaneous implantation. In sheep, blood contact increased tissue calcification significantly, mainly in aortic wall samples. Arterial pressure did not enhance mineralization of aortic wall tissue.     

Role of nonesterified fatty acids in necrotizing pancreatitis: an in vivo experimental study in rats

INTRODUCTION: In acute pancreatitis, nonesterified fatty acids (NEFA) might be released by lipase and cause tissue necrosis by their detergent properties, but this has not been established in vivo. AIMS: To measure the release of NEFA in the blood stream, pancreatic tissue, and peritoneal cavity during taurocholate-induced acute necrotizing pancreatitis in rats. METHODOLOGY: Ascites and blood were repeatedly sampled; after 24 hours, pancreatic lesions were scored, and NEFA were measured in the pancreas. The effects of a specific lipase inhibitor (Tetrahydrolipstatin [THL]) were also studied. RESULTS: A slight transient increase (22%) of NEFA concentration was observed in systemic circulation but did not parallel the time course of lipase activity, arguing against an intravascular production of NEFA by circulating lipase. Pancreatic NEFA did not differ between rats with pancreatitis and control rats. NEFA in ascites increased to threefold the basal value immediately after taurocholate and decreased rapidly thereafter, whereas lipase increased later in ascites and remained elevated during the 24-hour duration of the experiment. Lipase inhibition by THL neither modified the early increase of NEFA in ascites, nor altered the macroscopic, enzymatic, and histologic evolution of pancreatitis. CONCLUSION: This in vivo study does not confirm the hypothetical role of NEFA produced by pancreatic lipase in the necrotic process and its systemic complications, up to now mainly suggested on the basis of ex vivo experiments.     

Amelioration of adriamycin skin necrosis: an experimental study.

Skin necrosis following subcutaneous Adriamycin extravasation is a significant clinical problem. In this study Adriamycin dilution and various drugs were tested for their ability to ameliorate this toxic effect. When Adriamycin was diluted to a concentration of less than or equal to 0.25 mg/ml, no skin ulceration was observed. Drugs such as hydrocortisone, dexamethasone, lidocaine, bupivacaine, phentolamine, and hyaluronidase were ineffective in modifying Adriamycin skin necrosis. Care in iv drug administration and dilution of Adriamycin are the best means of preventing the sequelae of subcutaneous Adriamycin extravasation.     

Oval cell proliferation in cirrhosis in rats. An experimental study

Aim: Oval cells are liver stem cells involved in liver regeneration following liver damage. Previous studies have shown that pretreatment with a hepatocyte inhibitor is required to allow full oval cell activation. This study investigates whether oval cells develop and proliferate in a model of experimental liver fibrosis without pretreatment with a known hepatocyte inhibitor. Methods: The study comprised 66 male Wistar rats divided into two groups: A (n = 6): controls; and B (n = 60): CCl(4) injection (intraperitoneally 2 mL/kg bodyweight 1:1 volume in corn oil twice weekly). Rats were sacrificed at four, eight and 12 weeks. Liver tissues were evaluated for the degree of fibrosis (Masson's trichrome), cell proliferation (Ki67 antigen), expression of alpha-fetoprotein (AFP) mRNA (RT-PCR and in situ hybridization), AFP protein (Western blot) and cytokeratin-19. Cells with morphologic features of oval cells that were cytokeratin 19 (CK19)+ and AFP mRNA+ were scored in morphometric analysis. Results: Oval cells were present in all 66 specimens; their percentage was higher in group B compared to group A (P < 0.001). AFP mRNA and protein expression increased as fibrosis advanced. Similarly, the numbers of CK19+, AFP mRNA+ and Ki67+ oval cells were higher in advanced fibrosis stages. Conclusion: This study demonstrates that oval cells develop and proliferate in a model of experimental liver fibrosis without pretreatment with a known hepatocytic inhibitor. However, further research is warranted in order to identify the exact molecular mechanisms involved in this process.     

Early effects of fibrin sealant on colonic anastomosis in rats: an experimental and case-control study

Background Leakage from colonic anastomoses leads to mortality and morbidity. Fibrin adhesives can be used to increase the strength of the anastomosis. In this study, we evaluated the early effects of fibrin sealant and hyaluronic acid-carboxymethylcellulose on colonic anastomosis in rats. Methods Anastomoses were made in the descending colon of 38 female Wistar-Albino rats, in three groups: control group (n=12), group 1 treated with hyaluronic acid-carboxymethylcellulose (n=16), and group 2 treated with fibrin sealant (n=10). After 72 hours, adhesion scores, bursting pressure, rupture strength and histopathologic healing scores were evaluated. Results Due to postoperative mortality, we evaluated 10, 10 and 9 rats in the control group and in groups 1 and 2, respectively. Of these, we excluded 4, 5 and 4 rats that had macroperforations at autopsy. In the remaining rats, bursting pressure (123.2±14.8 mmHg) and rupture strength (400±16 mg) in the fibrin sealant group were significantly greater than in the two other groups (Control: 68.0±10.6 p=0.006 and 325±52 p=0.009; Group 1: 74.0±9.8 p=0.03, 330±27 p=0.016). However, we did not observe any significant difference between adhesion scores (2.5±0.6, 2.0±0.7, 2.0±0.7, p=0.343). Conclusions In this experimental study, fibrin sealant increased bursting pressure and rupture strength of colonic anastomoses while hyaluronic acid-carboxymethylcellulose had no effetcs in rats, but both of them showed no effect on adhesion scores. In order to use fibrin sealant to decrease the rate of early leakages from colonic anastomoses, further studies have to be performed.     

Pathophysiological role of secretory type I and II phospholipase A2 in acute pancreatitis: an experimental study in rats.

BACKGROUND: In human acute pancreatitis two different types of secretory phospholipase A2 (PLA2) have been found. AIM: To analyse the specific pattern of distribution of these PLA2 activities and their pathophysiological role in experimental acute pancreatitis. SUBJECTS AND METHODS: Catalytic activities of secretory type I (pancreatic) and type II (non-pancreatic) PLA2 and the protein concentration of immunoreactive pancreatic PLA2 (IR-PLA2) in serum and pancreatic tissue of rats with cerulein (mild form) and sodium taurocholate (severe form) induced acute pancreatitis were determined. RESULTS: Cerulein infusion caused a significant increase in type I PLA2 activity (p < 0.01) and IR-PLA2 protein concentration (p < 0.01) in serum and pancreas, whereas type II PLA2 activity remained unchanged during the 12 hour observation period. Histology showed no significant tissue destruction. In sodium taurocholate induced acute pancreatitis type II PLA2 activity significantly increased, reaching values over 10-fold higher than controls (p < 0.01), whereas IR-PLA2 protein concentration and type I PLA2 activity were only marginally increased. In this severe model of acute pancreatitis significantly lower values were detected than in the control pancreas (p < 0.002) for PLA2 activity and IR-PLA2 protein concentration. Histology showed parenchymal and fat necroses with haemorrhage, oedema, and inflammatory cell infiltration. CONCLUSIONS: Type I PLA2 activity is dependent on the IR-PLA2 protein concentration in serum and pancreatic tissue. The type II PLA2 activity is not stimulated by cerulein, which indicates an extra-acinar origin of this enzyme. Type II PLA2 activity is significantly increased in sodium taurocholate induced acute pancreatitis indicating its role in the local necrotising process and involvement in the systemic effects in severe acute pancreatitis.