Effect of age and neurovascular grafting on the mechanical function of medial gastrocnemius muscles of Fischer 344 rats

Both aging and grafting of whole skeletal muscle are associated with decreased specific force and resistance to fatigue. This study tested the hypothesis that the recovery of mechanical function in nerve-repair skeletal muscle grafts in senescent rats would be impaired compared with recovery in similar grafts in younger animals. Following a 120-day recovery period, the contractile properties of grafted medial gastrocnemius (MGN) muscles from young-mature (6 months), middle-aged (12 months), and senescent (24 months) Fischer 344 rats were measured and compared to age-matched controls. Although there was full recovery of muscle mass, grafting and aging alone both were associated with diminished maximum twitch and tetanic tension, maximum power, and maximum sustained power. In addition, the deleterious effect of grafting on maximum tetanic tension, specific force, and sustained power of MGN muscle was significantly greater in old animals. These findings suggest that aging limits full recovery of the quality of muscle contractions from the nerve-repair grafting procedure, possibly due to an age-related impairment of reinnervation.     

Changes in fecal fat excretion from allo-intestine transplanted rats after discontinuance of immunosuppressive agents

We have previously shown in a rat model of segmental small bowel transplantation, that an ileal graft was more favorable for lipid absorption than a jejunal graft. In the present study, we investigated changes in the lipid absorption of allo-ileal grafts after the withdrawal of an immunosuppressant (methyldeoxyspergualin; given for 1 or 2 weeks at 2.5 mg/kg per day) and compared the findings with the results of histological examinations. Heterotopic segmental small bowel transplantation (SBT) was performed using cuff anastomoses in the inbred rat strain combination DA (RT1^a) and LEW (RT1^l). Orthotopic SBT was performed as reconstruction SBT. Reconstruction after resection of the original intestinal tract of the recipient was performed on the seventh day after heterotopic segmental ileal grafting. For the histological evaluation of graft rejection, we performed biopsies in the heterotopic model and autopsies in the orthotopic model. Fecal fat excretion from the orthotopically reconstructed recipients was measured by Folch's method. One- and 2-week use of methyldeoxyspergualin allowed the heterotopic allografts to remain intact histologically for 16.8 ± 5.6 and 25.3 ± 3.3 (mean ± SD) days, respectively, whereas the grafts were rejected at 7.3 ± 1.1 days when the immunosuppressive drug was not used. All the recipients in the orthotopic group had died by 19 days after reconstruction. After discontinuance of the immunosuppressive agent, fat excretion in feces in the surviving orthotopic grafted rats had increased markedly prior to histologically assessed heterotopic graft rejection. Evaluation of fecal lipid excretion may be a useful parameter for detecting graft rejection in rats. (Received Jan. 7, 1998; accepted Sept. 25, 1998)     

Luteinizing-hormone-mediated precocious puberty induced in female rats by a prepuberal pituitary graft

The present study analyzes the mechanism of precocious puberty induced in female rats after a 'young' pituitary graft (obtained from 21-day-old animals). For this purpose, the following experiments have been performed: (1) female rats were grafted or sham-operated on day 21 with a littermate's pituitary the follicle-stimulating hormone (FSH), luteinizing hormone (LH) and estradiol plasma levels as well as the ovarian, uterine and adrenal weights were determined at different times after the graft; (2) female rats grafted or sham-operated on day 21 were treated with 0.2 ml of LH antiserum (LHAS) or the same volume of a normal horse serum (NHS); (3) female rats were injected on day 1 of life with 0.1 mg of estradiol benzoate or olive oil. Groups of these animals were decapitated daily between days 6 and 21 in order to measure gonadotropins and prolactin (PRL) pituitary content. Since on day 21 estrogenized females showed decreased gonadotropin content and normal PRL content, females in experiment 4 were grafted on day 21 with pituitaries obtained from control or neonatally estrogenized female rats. The results obtained showed that FSH, LH and estradiol plasma levels as well as ovarian and uterine weights increased after pituitary grafts. LHAS blocked the precocious puberty induced by the pituitary graft, and pituitaries obtained from neonatally estrogenized female rats were unable to modify the occurrence of puberty when grafted. In conclusion, this work evidences that precocious puberty induced by 'young' pituitary grafts was mediated by the increase in LH secretion from the graft.     

Single stage cell seeding of small diameter prosthetic cardiovascular grafts

Small-diameter prosthetic cardiovascular bypass grafts have high occlusion rates. Thrombogenicity caused by the lack of endothelial cells (ECs) on the luminal surface of the grafts is one of the main reasons for its occlusion. One strategy to improve the clinical performance of cardiovascular prosthetic grafts has been to seed its luminal surface with a monolayer of the patient's own ECs. In this strategy a "two stage" seeding procedure is utilized whereby cells obtained from a vein are amplified in cell culture, then seeded onto a fibrin-arginine-glycine-aspartate (RGD) tripeptide-enriched expanded polytetrafluoroethylene (ePTFE) graft in a rotating bioreactor for one week, after which it is surgically implanted. This achieves patency rates approaching those of vein grafts. The disadvantage of two stage seeding is that it requires culture facilities, a large amount of RGD, which is expensive and is confined to elective cases because of the delay between cell cultivation, seeding, and graft implantation. A single stage seeding using freshly extracted ECs that is transplanted onto the graft at the same time frame of the bypass operation without the need for cell cultivation would be an ideal answer for the disadvantages of two stage seeding. Animal trials have been successful but human trials of single stage seeding have been disappointing. It has been hypothesized that extracted ECs are scarce, furthermore, they are washed off the graft surface once exposed to blood flow. This review examines the various techniques/technologies to improve endothelial cell extraction from various sources and retention onto the luminal surface of prosthetic cardiovascular grafts in order to develop a clinically applicable strategy for single stage seeding.     

小鼠下腔静脉移植模型的建立和改良

目的建立异体下腔静脉移植于颈动脉的动物模型,以模拟冠状动脉旁路移植术后静脉桥再狭窄的病理过程。方法游离供体小鼠下腔静脉,切断受体小鼠右颈总动脉,实验组采用"袖套式"结扎吻合法、对照组采用缝合法将下腔静脉两端分别与颈总动脉断端行端端吻合。术后对比两组血管通畅情况,于术后1周、2周、4周、6周对实验组小鼠取材,行HE染色及免疫组织化学染色观察桥血管病理变化情况。结果实验组1例麻醉过量死亡,手术完成即刻各吻合口均通畅,无出血、狭窄及血管扭曲等情况。术后2例急性血栓形成,手术平均耗时46.0±10.6 m in;对照组手术完成即刻2例近端吻合口出血死亡,术后2例急性血栓形成,手术平均耗时68.0±12.4m in;后期静脉桥管壁逐渐增厚,管腔逐渐狭窄,HE染色及免疫组织化学染色显示中膜、内膜不同程度增生及炎症细胞浸润。结论小鼠异体下腔静脉移植模型能真实反映冠状动脉旁路移植术后静脉桥狭窄的情况,是进一步研究移植静脉内膜增生的理想模型。"袖套式"结扎吻合法建立小鼠下腔静脉移植模型,较以往常用的吻合法时间短、出血少、通畅率高。     

纤维蛋白生物胶外周支持对大鼠颈静脉移植物的增殖和凋亡的影响

目的研究纤维蛋白胶血管外周支持对静脉移植物平滑肌细胞增殖、凋亡的影响。方法建立大鼠颈总动脉自体颈静脉移植模型,按照有无纤维蛋白胶血管外周支持,分为外周支持组、无外周支持组,每组24只。术后1周、2周、4周分别切除移植静脉,用免疫组织化学方法检测静脉移植物平滑肌细胞增殖细胞核抗原(PCNA)表达,用原位DNA断裂位点3’-羟基末端标记(TUNEL)法检测静脉移植物平滑肌细胞凋亡的变化,以及检测内膜厚度。结果静脉移植术后1-4周,无外周支持组静脉移植物血管平滑肌细胞的凋亡和增殖均明显升高,内膜明显增厚;纤维蛋白胶血管外周支持组静脉移植物血管平滑肌细胞的凋亡和增殖同处于低水平,内膜增厚不明显。两组静脉移植物血管平滑肌细胞的凋亡和增殖具有显著相关性。结论纤维蛋白胶外周支持可以抑制血管平滑肌的增殖和凋亡,使两者同时处于低水平,一方面减少细胞凋不足所造成的对血管重塑造成的影响,另一方面使凋亡程度与巨噬细胞及正常血管平滑肌吞噬作用达到平衡,抑制了静脉移植物的内膜增生。     

Adverse effects of high dose aspirin on platelet adhesion to experimental autogenous vein grafts

Prostacyclin (PGI2) production and platelet adhesion were studied in veins grafted into the arterial system of rabbits. Animal groups consisted of: no treatment; low dose aspirin (ASA) (0.5 mg . kg-1 X 24 h-1) plus dipyridamole (2 mg . kg-1 X 6 h-1); high dose ASA (40 mg . kg-1 X 24 h-1) plus dipyridamole (2 mg . kg-1 X 6 h-1); dipyridamole (2 mg . kg-1 X 6 h-1) alone. Results showed that vein grafts from animals treated with high dose ASA plus dipyridamole produced significantly less PGI2 than the other three groups (p less than 0.05 compared with the dipyridamole group; p less than 0.01 compared with the other two groups). In addition, there was significantly greater platelet deposition on the vein grafts from this high dose ASA group as compared to the low dose ASA group (p less than 0.05). By contrast, animals treated with dipyridamole alone had significantly less platelet deposition compared to both the control and high dose ASA groups (p less than 0.05). High dose ASA given to prevent thrombotic occlusion following coronary artery bypass grafting may, by reducing PGI2, result in enhanced platelet deposition. This in turn is likely to increase intimal hyperplasia as has been demonstrated previously with high dose ASA. Clinical studies, which have shown the early anti-thrombotic benefits of high dose ASA plus dipyridamole, have not measured graft intimal thickness. Since this process is an important cause of graft narrowing, ASA, in high dose, may adversely affect long-term graft survival.     

Gene transfer of endothelial nitric oxide synthase to the penis augments erectile responses in the aged rat

Nitric oxide (NO), a mediator involved in penile erection, is synthesized by the nitric oxide synthase (NOS) family of enzymes. It has been shown that NOS activity decreases with age. To determine whether adenoviral-mediated overexpression of endothelial NOS (eNOS) could enhance erectile responses, we administered a recombinant adenovirus containing the eNOS gene (AdCMVeNOS) into the corpora cavernosum of the aged rat. Adenoviral expression of the beta-galactosidase reporter gene was observed in cavernosal tissue 1 day after intracavernosal administration of AdCMVbetagal; 1 day after administration of AdCMVeNOS, transgene expression was confirmed by immunoblot staining of eNOS protein, and cGMP levels were increased. The increase in cavernosal pressure in response to cavernosal nerve stimulation was enhanced in animals transfected with eNOS, and erectile responses to acetylcholine and zaprinast were enhanced at a time when the erectile response to the NO donor sodium 1-(N,N-diethylamino)diazen-1-ium-1,2-diolate was not altered. These results suggest that in vivo gene transfer of eNOS, alone or in combination with a type V phosphodiesterase inhibitor, may constitute a new therapeutic intervention for the treatment of erectile dysfunction.     

Esophageal replacement in rat using porcine intestinal submucosa as a patch or a tube-shaped graft

This study compares the efficacy of porcine intestinal submucosa (SIS) patch graft versus SIS-tube graft in esophageal replacement, using a novel esophageal regeneration model. Clinical function, as well as macroscopic and microscopic morphology were evaluated in both SIS-treated groups. We performed semi-circumferential esophageal excision followed by repair of the defect using either a SIS-patch graft (group I) or segmental esophageal excision followed by a SIS-tube interposition graft (group II) in rats. The 28-day survival rate was significantly different between the SIS-treated groups (100% in group I vs. 0% in group II). Unlike the rats in group II, which died within the first postoperative month due to esophageal dysfunction, all surviving animals in group I resumed a normal solid diet within a few days after surgery, without signs of esophageal dysfunction and gained weight. Barium swallow studies showed no evidence of fistula, significant stenosis or diverticula. No hematological or serum biochemistry abnormalities were found. By day 150 the SIS patch was replaced by esophageal-derived tissues. In the rat model, a patch graft technique using SIS appeared to induce esophageal regrowth and provided an initial and long-term satisfactory function, while a tube-shaped graft technique using SIS was unsuccessful.     

SDF-1α在大鼠静脉移植物再狭窄中的作用

目的:观察基质细胞衍生因子（SDF）-1α在大鼠自体颈外静脉移植物新生内膜增厚中的作用。方法:将60只体质量在250~300 g的 SD雄性大鼠随机分为模型组和CXC趋化因子受体4拮抗剂（AMD3100）组［AMD3100 1mg/(kg·d)×7腹腔注射］,每组30只,建立大鼠自体颈外静脉端侧吻合到颈总动脉的移植物模型后,给予不同的干预。两组大鼠分别在术后0、3、7、14及28 d取静脉移植物,经HE染色后观察移植物新生内膜的厚度;用免疫荧光染色法检测SDF-1α的表达。结果:随着时间的延长,模型组移植物新生内膜的厚度逐渐增加（P<0.01）。与模型组相同时间点相比较,AMD3100组新生内膜的厚度减少（P<0.01）;免疫荧光染色法显示,SDF-1α在移植物中的表达增加,术后7 d表达达到高峰,术后28 d仍能检测到SDF-1α表达。结论:SDF-1α参与了静脉移植物新生内膜的增厚,AMD3100能减轻新生内膜的增厚。     

Marrow transplantation with or without donor buffy coat cells for 65 transfused aplastic anemia patients

Sixty-five multiply transfused patients with severe aplastic anemia were given cyclophosphamide followed by grafts anemia were given cyclophosphamide followed by grafts from HLA-identical siblings. The effect of the administration of viable donor buffy coat cells following the marrow inoculum was evaluated with regard to graft rejection and survival. Results in 43 patients so treated are presented along with those in 22 concurrent patients given marrow alone. Most patients given buffy coat had positive in vitro tests of sensitization indicating a high risk for graft rejection, while all but one of the patients given marrow alone had negative tests. Thirty of the 43 (70%) patients given marrow and buffy coat are alive between 10 and 61 mo (median 36) after grafting; 4 died after graft rejection and 6 with acute or chronic graft-versus-host disease (GVHD). Eleven of the 22 (50%) patients given marrow alone are alive between 29 and 65 mo (median 52); 7 died after graft rejection and 3 with GVHD. The addition of buffy coat cell infusions to the marrow inoculum reduced the risk of rejection and increased survival in the currently reported transfused patients when compared to patients grafted before 1976. However, there was an increased risk of chronic GVHD. Recipients of marrow from female donors survived slightly better (73%) than recipients of male marrow (58%).     

Fibrin glue coating of e-PTFE prostheses enhances seeding of human endothelial cells

A laboratory study was undertaken to improve the initial count of endothelial cells (EC) adhering to the wall of e-PTFE prostheses when seeding of human EC is attempted. In our experiments pretreatment of the prosthetic wall with commercially available fibrin glue (Tissucol) improved the reliability of the seeding procedure. The number and the distribution of EC seeded onto fibrin glue presealed e-PTFE prostheses was compared to the number and distribution of EC adhering to blood preclotted grafts 24 hours following the initial seeding procedure. Fibrin glue presealed grafts showed a higher number of initially adhering EC and a more equal distribution over the graft surface when compared to blood pretreated grafts. Our results suggest that the use of fibrin glue enhances the seeding of human EC on e-PTFE grafts.     

Skeletal muscle stem cells do not transdifferentiate into cardiomyocytes after cardiac grafting

Skeletal muscle cell-derived grafts in the heart may benefit myocardial performance after infarction. Several studies have suggested that skeletal muscle stem cells (satellite cells) from adult muscle undergo transdifferentiation into cardiomyocytes after grafting into the heart, but expression of cardiac markers in graft cells has not been rigorously confirmed. To determine the fate of satellite cell-derived grafts in the heart, adult rat satellite cells were tagged in vitro with bromodeoxyuridine (BrdU) and grafted into normal hearts of syngeneic rats. At 4 and 12 weeks the graft cells formed multinucleated, cross-striated myofibers that expressed fast skeletal myosin heavy chain (MHC), thus indicating a mature skeletal muscle phenotype. Double staining for the BrdU tag and cardiac-specific markers was employed to identify transdifferentiation. Aside from four questionable cells, none of the 11 grafts examined expressed alpha-MHC, cardiac troponin I, or atrial natriuretic peptide. At 4 weeks, grafts expressed beta -MHC, a hallmark of slow twitch myofibers. By 12 weeks, however, the myofibers had atrophied and downregulated beta-MHC. Grafts never expressed the intercalated disk proteins N-cadherin or connexin43, hence electromechanical coupling did not occur. In conclusion, satellite cells differentiate into mature skeletal muscle and do not express cardiac-specific genes after grafting into the heart. Thus, transdifferentiation into cardiomyocytes did not occur.     

Striatal progenitors derived from human ES cells mature into DARPP32 neurons in vitro and in quinolinic acid-lesioned rats

Substitutive cell therapy using fetal striatal grafts has demonstrated preliminary clinical success in patients with Huntington's disease, but the logistics required for accessing fetal cells preclude its extension to the relevant population of patients. Human embryonic stem (hES) cells theoretically meet this challenge, because they can be expanded indefinitely and differentiated into any cell type. We have designed an in vitro protocol combining substrates, media, and cytokines to push hES cells along the neural lineage, up to postmitotic neurons expressing striatal markers. The therapeutic potential of such hES-derived cells was further substantiated by their in vivo differentiation into striatal neurons following xenotransplantation into adult rats. Our results open the way toward hES cell therapy for Huntington's disease. Long-term proliferation of human neural progenitors leads, however, to xenograft overgrowth in the rat brain, suggesting that the path to the clinic requires a way to switch them off after grafting.     

Secretion of melanocyte-stimulating hormone and adrenocorticotropin from transplanted pituitary pars intermedia in stressed and nonstressed rats

Rats bearing kidney grafts of the pituitary pars intermedia were divided into three groups: unstressed, acutely stressed, and chronically stressed. Corresponding sham-operated rats were used for comparisons. Twenty days after grafting, the rats were sacrificed and alpha-melanocyte-stimulating hormone (alpha-MSH), adrenocorticotropin (ACTH), and corticosterone were estimated in plasma. The adrenal/body weight ratio and DNA content of the glands were also investigated. The following results were obtained: MSH was found not to be increased in unstressed rats, but it was in grafted animals subjected to acute and chronic swimming stress. ACTH and corticosterone rose in all three groups. Adrenal/body weight ratio and DNA content increased only in grafted chronically stressed rats. Moreover, plasma corticosterone was found higher in grafted hypophysectomized rats than in non-grafted hypophysectomized animals. Administration of ergocryptine to nonstressed grafted rats induced a decrease in the blood content of ACTH and MSH, indicating that the grafts were the source of a part of the circulating ACTH. On the other hand, the fall in MSH levels could show the effect of the drug upon the pars intermedia. Comparison of the ratios of both hormones released in incubations showed that grafts secreted more ACTH than MSH; on the other hand, when intact neurointermediate lobes were incubated, MSH predominated over ACTH. For the first time it is demonstrated that the pars intermedia can secrete ACTH in vivo. Nevertheless, the ability to secrete this hormone is not a property of normal intact pars intermedia, but it manifests in the transplantations probably due to the overactivity of light cells induced by chronic stoppage of dopaminergic inhibition.     

增龄对大鼠阴茎勃起功能的影响

目的　探讨增龄在勃起功能障碍 ( ED)中的作用。方法　应用注射阿朴吗啡和电刺激海绵体神经的方法 ,观察低月龄大鼠与老龄大鼠阴茎勃起情况 ,采用免疫组化方法检测大鼠阴茎组织一氧化氮合酶 ( NOS)的染色情况。结果　注射阿朴吗啡后 ,老龄大鼠阴茎勃起次数要少于低月龄大鼠 ( P<0 .0 5) ;电刺激海绵体神经后 ,老龄组大鼠阴茎海绵体内压增幅与低月龄大鼠相近 ( P>0 .0 5) ,但勃起潜伏期延长 ( P<0 .0 5) ;组织化学染色显示低月龄大鼠阴茎组织 NOS的染色明显强于老龄大鼠。结论　增龄对大鼠阴茎勃起功能有一定的影响 ,主要表现在中枢调节及 NOS水平下降两方面     

微创经左胸小切口非体外循环单支、多支冠状动脉旁路移植术33例

目的 探讨左侧肋间小切口非体外循环单支、多支冠状动脉旁路移植术的安全性和可行性。方法 回顾性分析2014年5月~2019年10月左胸前外侧小切口非体外循环下冠状动脉旁路移植术33例资料。单支病变17例,多支病变16例。左胸前外侧小切口6cm-10cm,直视下获取左乳内动脉(LIMA),完成LIMA-左前降支(LAD)吻合,升主动脉（Ao）-大隐静脉(SVG)序贯-对角支(D)或中间支（ICA）-钝缘支(OM)-后降支(PDA)或左室后支(PLV)共2~4支旁路移植血管吻合。结果 全组LIMA-LAD桥32例,Ao-SVG-LAD 1例。Ao-SVG-D 2例,Ao-SVG-OM 2例、Ao-SVG-OM-PDA 2例,Ao-SVG-ICA-PDA 3例,Ao-SVG-D-OM-PDA 4例,Ao-SVG-D-OM-PLV 3例。33例手术均顺利完成,围术期无死亡、心肌梗死、脑卒中、呼吸衰竭、肾功能衰竭、切口感染等并发症。术后呼吸机时间7h~18 h(9.14±3.82)h;ICU时间6h~20 h（12±8）h。术后住院5d~11d(8±3)d。出院时复查冠状动脉CT,33例均提示左乳内动脉桥、大隐静脉序贯桥通畅性良好。随访3个月~3年,平均8个月,无死亡、心绞痛和心肌梗死。30例复查冠状动脉, LIMA桥、SVG序贯桥通畅性良好。结论 左侧肋间小切口非体外循环下多支冠状动脉旁路移植术安全可行。     

Time-dependent effects of increased serum prolactin levels on corticosterone synthesis and secretion in male rats

To investigate the role of prolactin (PRL) on adrenal cortex function, male rats of the Wistar strain were rendered hyperprolactinemic by the grafting of one pituitary gland under the kidney capsule at 30 days of life. Age-matched animals were sham-operated to be used as controls. The well known increase of serum PRL levels, in grafted rats, observed in samples taken at 10 a.m. was only maintained at 2 a.m. on days 2, 4 and 14 after grafting, when compared to sham-operated rats. A differential time-dependent effects was observed for corticosterone (B) secretion. An increase in adrenal B content is observed during the whole period studied in grafted animals, as compared to sham-operated animals being statistically significant on days 2, 4, 14 and 40 days after the transplant operation. A biphasic pattern is described for serum B levels: whereas increased serum B levels were found on days 2 and 8 of the experimental period; a decrease in serum B levels were found in the chronic situation. The expected increase in adrenal weight was not sustained over the whole period studied being only increased on days 4, 8 and 30 after the grafting. All these data suggest that PRL exert a time-dependent modification in B secretion from the adrenal gland.     

Thymus graft reconstitution of T-cell-deprived mice infected with Trypanosoma musculi

T-cell-deprived CBA mice were given thymus graft implants during the course of an infection with Trypanosoma musculi and at a time when the parasitaemia was high. As a consequence of the grafts, most of the mice survived the infection whereas control ungrafted mice died. In grafted animals there was generally a period of 6&80 days after grafting during which time parasitic numbers remained high, and a further period of 200 or more days when trypanosomes were still detectable in the circulation. The mice were highly variable in their responses and possible reasons for this are considered.