GaAs (904-nm) laser radiation does not affect muscle regeneration in mouse skeletal muscle.

BACKGROUND AND OBJECTIVE: We evaluated the effect of GaAs (904-nm) laser, applied directly to the skin of injured muscle, in muscle regeneration. STUDY DESIGN/MATERIAL AND METHODS: Muscle injury was induced in the Tibialis anterior (TA) muscle by ACL myotoxin (5 mg/kg). Two groups were irradiated with doses of 3 (n = 8) and 10 J/cm(2)(n = 8). GaAs laser (power 1.5 mW, intensity 7.5 mW/cm(2), spot 0.2 cm(2)) was applied daily for five days. Contralateral TA received a sham procedure. RESULTS: Similar morphological aspects were found in both laser irradiated and sham muscles. No differences were found in the muscle weight, but animals irradiated with 10 J/cm(2) showed a significant gain of body weight (P = 0.002). CONCLUSIONS: Doses of 3 and 10 J/cm(2) of GaAs laser were not efficient to promote significant morphological changes in the regenerated skeletal muscle, but the dose of 10 J/cm(2) promoted significant gain of body weight.     

EMLA does not permit pain-free retrobulbar injection

BACKGROUND: Retrobulbar injection can be associated with significant pain, due to both needle insertion and deposition of the local anaesthetic solution. The local anaesthetic cream EMLA (eutectic mixture of local anaesthetics) which contains a mixture of lignocaine and prilocaine has been shown to reduce the pain associated with skin puncture. The efficacy of EMLA in alleviating the pain of retrobulbar injection for cataract surgery was assessed in this study. METHODS: In this, randomised double-blind study, EMLA (n = 53) or lignocaine 5% ointment (n = 50) was administered to the inferior orbital margin at least 45 min before retrobulbar block in 103 patients. Pain assessed during retrobulbar block was marked subjectively by the patient on a 10-point numerical rating scale. RESULTS: Median verbal pain scores were 3.0 with an interquartile range of 1.5-6.5 in the control group and 3.50 with an interquartile range of 2.0-6.0 in the EMLA(R) group (P = 0.67). There was no significant difference between the EMLA group and the lignocaine ointment group according to this pain assessment. CONCLUSION: EMLA does not permit pain-free retrobulbar injection.     

Gene therapy in wound repair and regeneration

The potential use of gene therapy to treat human disease increases with the development of various physical, chemical, and biological methods to deliver genes to mammalian cells, and with our rapidly expanding knowledge of the human genome. One area of therapeutic interest for gene therapy is the treatment of wound healing disorders. Most recently, recombinant human growth factor therapy has been examined as a means to treat problem wounds. However, this approach suffers from the difficulty in providing an accurate dose of growth factor and the expense of the recombinant proteins. Delivery of a gene that could be expressed within the wound is an attractive alternative to application of the protein. This review discusses several methods that have been used to deliver genes encoding growth factor proteins into wounds and the advantages/disadvantages of each approach. Novel methods to regulate the expression of the transgene are also presented, highlighting the ability of these unique vector systems to adjust gene dose as the wound heals. We expect that gene therapy will become a significant treatment modality for those wound healing pathologies refractory to other wound management approaches in the years ahead.     

Famotidine does not inhibit liver regeneration

The H2-blockers, cimetidine and ranitidine, are reported to inhibit liver regeneration. In this work, the effects of a new powerful H2-receptor antagonist, famotidine, on liver regeneration were studied in rats. The animals were divided into three groups: group I in which a standard two-thirds hepatectomy was performed, group II in which the rats were treated with famotidine (intramuscular dose of 0.8 mg/kg body weight) on the day of operation and 24 and 48 h after hepatectomy, and group III in which the animals were intramuscularly injected with a larger dose of famotidine (1.2 mg/kg body weight) in the same way as group II. The histology and mitotic index of remnant livers and serum levels of aminotransferase and albumin were examined from 24 h to 10 days after the operation. The treatment with famotidine (groups II and III) did not inhibit hepatocyte mitosis but, on the contrary, raised the index on day 3 after hepatectomy when compared with the controls (group I). The albumin synthesis was well preserved in the famotidine-treated animals. The noninhibitory effects of famotidine on liver regeneration are discussed.     

EH Networks as a scaffold for skeletal muscle regeneration in abdominal wall hernia repair

Incisional hernias are a common clinical problem occurring in up to 10% of all patients undergoing abdominal procedures. Primary closure, synthetic biomaterials, as well as xenografts and allografts have been used in hernia defect repair. Despite these approaches, the incidence of hernia recurrence ranges from 32% to 63%. To address this high recurrence rate, we propose an incisional hernia treatment that utilizes a functional biomaterial developed for skeletal muscle regeneration. In particular, we have developed a cyclic acetal biomaterial (EH network) based on 5-ethyl-5-(hydroxymethyl)-beta,beta-dimethyl-1,3-dioxane-2-ethanol diacrylate. Initial tests of the scaffold's mechanical properties indicate that the complex modulus of the EH network decreased after a significant increase in initiator concentration. Subsequent studies indicate that EH networks promote myoblastic cell attachment and proliferation as well as delivers functional insulin-like growth factor-1 to an in vitro population of skeletal myoblasts. This work establishes that an EH network, a degradable cyclic acetal biomaterial, can function as a scaffold for skeletal muscle engineering.     

创伤修复与组织再生面临的新课题

创伤修复与组织再生面临的问题很多,但近年来人们主要关注两个方面,一是创面愈合的速度问题,即怎样在短时间内使创面迅速地封闭以减少并发症的发生。二是创面愈合的质量问题,即怎样使受创的组织解剖结构和功能恢复到损伤前的状态。对于前一个问题,通过近20年的努力,特别是外科治疗手段的改进和各种综合治疗措施的应用,包括胶原酶用于小面积创面的清创、基因工程生长因子药物应用于加速创面愈合等,已经使急性创面（主要包括浅二度烧伤、深二度烧伤和供皮区等）的愈合时间较传统的治疗方法提前。     

Histomorphologic examination of skeletal muscle preparations does not differentiate between malignant hyperthermia-susceptible and -normal patients

BACKGROUND: It has been suggested that malignant hyperthermia (MH) can be diagnosed by specific myopathologic alterations. The purpose of this study was to investigate whether there are characteristic myopathologic changes in skeletal muscles of MH-susceptible (MHS) compared with MH-normal (MHN) patients. METHODS: Four hundred forty patients with clinical suspicion of MH were classified as MHN, MH equivocal (MHE), or MHS by the in vitro contracture test with halothane and caffeine. In addition, a small muscle sample excised from each patient was analyzed by histologic, histochemical, immunohistochemical, and computer-aided morphometric methods. RESULTS: MHN was diagnosed in 243 patients, MHE was diagnosed in 65, and MHS was diagnosed in 132. No myopathologic abnormalities were found in 53.5% of the MHN, 53.9% of the MHE, and 56.1% of the MHS patients. Thirty-five percent of all patients showed one, 9.8% showed two, and only 0.9% showed three different pathologic findings within skeletal muscle preparations. The frequency of pathologic findings did not differ between the MHN and the MHS patients; only fiber type I predominance was observed more often in MHN. MHE patients could not be assigned to a diagnostic group by detection of myopathologic alterations. In six clinically unaffected patients, a former unrecognized myopathy, such as central core disease, was diagnosed. This disease is characterized by a specific alteration (cores). CONCLUSIONS: Histologic differences between MHS and MHN statuses could not be demonstrated in this study. Histopathologic examinations can neither improve the diagnosis of MH nor contribute to a better definition of the MH status. However, histopathologic examinations might be useful to detect formerly unrecognized specific myopathies.     

Denervation retards but does not prevent toetip regeneration

Toetips of mammals regrow after amputation by a process similar, but not identical, to that which occurs during regeneration of a newt limb. Nerve is needed as a mitotic stimulant for newt limb regeneration but the requirement for nerve during rodent digit-tip regeneration is not known. Nerve dependence in rats was tested by severing the sciatic nerve in one hindlimb, amputating digit-tips from the central digits of both hind feet, and comparing the amount of regrowth in innervated and denervated digits. Denervation delayed soft-tissue wound healing. However, denervation did not significantly affect bone regrowth when animals were examined at one month. Because we suspected delayed bone regrowth, we used a new method that we developed to follow bone growth at several time points in each animal. Termed visible bone fluorescence through nail, this technique used serial injections of fluorescent calcium-deposition markers and observation through the toenails to observe bone growth in living animals. Using this method it was possible to detect retarded bone regrowth in denervated digits. Thus, although denervation of rodent tips delayed both soft tissue healing and bone regrowth, it did not prevent ultimate restitution of the amputated part. This suggests that neurotrophic stimulation in the mammalian digit-tip is not identical to that documented during newt limb regeneration, and that growth stimulation may be provided by tissues other than nerve.     

ACE在皮肤组织损伤修复与再生中作用的研究

血管紧张素转化酶（angiot ensin-converting enzyme,ACE）是肾素-血管紧张素系统（renin-angiotensin system,RAS）激活过程中的关键性限速酶之一,可催化血管紧张素Ⅰ水解生成RAS最重要的活性产物血管紧张素Ⅱ。ACE也可使具有扩张血管反应的缓激肽生成苯丙-精二肽,还可直接作用于肾上腺皮质促进醛固酮分泌。近年来发现ACE除了降解血管紧张素I和缓激肽外,还能降解其它产物如：β-内啡肽、P物质、Ac-SDPK等。同时,ACE和中性内肽酶（neutral endopeptidase,NEP）作为终止皮肤神经-内分泌介质作用的关键酶可调控皮肤细胞的存活、创伤愈合和组织再生。本文主要阐述近年来有关ACE及其底物在皮肤组织损伤修复与再生中作用的相关研究。     

Recovery of skeletal muscle after laceration and repair

Few data are available regarding structural and functional recovery of lacerated skeletal muscle after repair. This study used the extensor digitorum longus muscle of rabbits to document recovery after laceration and repair and a healing period of 12 weeks. Completely lacerated muscles recovered approximately 50% of their ability to produce tension but were able to shorten to 80% of normal. Partially lacerated muscle bellies recovered approximately 60% of their ability to produce tension and normal ability to shorten. Histologic specimens revealed that the lacerations did not cause necrosis of either segment. After the recovery period, histologic and histochemical sections revealed that the distal segment initially isolated from the nerve supply showed histologic changes of fiber atrophy and size variability, increased fibrosis, and nuclear centralization suggestive of denervation. Dense scar separated the two fragments. Data show that skeletal muscle can recover useful but not normal function after laceration and repair.     

Insulin-stimulated glucose uptake does not require p38 mitogen-activated protein kinase in adipose tissue or skeletal muscle

It has been proposed that p38 mitogen-activated protein kinase (MAPK) isoforms sensitive to the pyridinylimidazole compounds SB 203580 and SB 202190 may participate in the acute insulin-dependent activation of glucose transporters recruited to the plasma membrane of adipocytes and skeletal muscle. Here, we explore whether these kinases support the insulin stimulation of glucose uptake in these tissues by investigating the effects of a genetic loss in p38beta and that of the p38 MAPK inhibitor SB 203580. Glucose uptake in adipocytes and soleus muscle was stimulated by insulin by up to fourfold irrespective of whether tissues were isolated from wild-type or p38beta-null mice. Consistent with this finding, mice lacking p38beta exhibited normal glucose tolerance, insulinemia, and glycemia compared with their wild-type counterparts. Insulin-stimulated glucose uptake was not inhibited by SB 203580 when adipocytes were preincubated with the drug at a cytocrit of 50%, but intriguingly, uptake was suppressed (by 35%) when the cytocrit was reduced by one-half. Despite the activation of glucose uptake at the higher cytocrit, insulin failed to induce any detectable activation of p38 MAPK, whereas p38 signaling was robustly activated by anisomycin in a SB 203580-sensitive manner. Although insulin also failed to induce any detectable activation of p38 MAPK in muscle, insulin-dependent glucose uptake was reduced by SB 203580 (approximately 44%) in muscle of both wild-type and p38beta-null mice. Our results indicate that p38beta is not required for insulin-stimulated glucose uptake in adipocytes or muscle. Moreover, given that insulin fails to promote any significant activation of p38 MAPK in these tissues and the finding that sensitivity of glucose uptake, but not that of the kinase, to SB 203580 can be influenced by cytocrit, we suggest that p38 signaling is unlikely to participate in any putative activation of transporters recruited to the cell surface by insulin and that SB 203580 suppresses insulin-stimulated glucose transport by a mechanism unrelated to its inhibitory effect on p38 MAPK.     

Laparoscopic inguinal hernia repair does not impair testicular perfusion

Background

Laparoscopic inguinal hernia repair techniques close the internal ring with a suture. Concern has been raised whether or not the testicular vessels are compromised with this technique. This study was undertaken to evaluate pre- and postoperative testicular perfusion and to compare it with healthy controls.

Patients and Method

Sixty-five boys (aged 6 weeks to 11 years; median, 1.4 years) with unilateral (n = 52) or bilateral (n = 13) inguinal hernias were treated laparoscopically. Testicular perfusion was measured using a recently developed neuromonitoring device (O2C; LEA Medizintechnik GmbH, Giessen, Germany), which combines light spectroscopy and laser Doppler technique. An optical probe was placed on the surface of each scrotal pouch for measurements at 2 depths (2 and 8 mm). Measurements involved oxygen (O₂) saturation at the venous end of capillaries, the amount of hemoglobin within microvessels, the blood flow within microcirculation, and the velocity of the blood in microcirculation. Measurements were conducted before and after anesthesia, before and after surgery, and 6 weeks later. Twenty-one healthy boys of similar ages served as controls.

Results

Measurements at 2-mm depth were unreliable. At 8-mm depth, the oxygen saturation of hemoglobin was between 62% and 75% (hypoxia would be <10%). The relative blood flow was between 160 to 235 arbitrary units, better than in healthy awake controls. Values were solely influenced by the administered fraction of inspired oxygen. Relative hemoglobin volume of the testes and blood flow velocity remained unchanged after surgery. Values were also normal when measured during early and long-term follow-up.

Conclusion

Laparoscopic inguinal hernia repair using suture closure of the internal inguinal ring does not impair testicular perfusion.     

Pregabalin does not impact peripheral nerve regeneration after crush injury

Timely repair and robust regeneration after traumatic peripheral nerve injury are essential to ensure optimal recovery. Pregabalin (Lyrica; Pfizer Inc., Morris Plains, NJ), frequently prescribed to attenuate neuropathic pain in patients with traumatic nerve injury, was evaluated for its potential to alter nerve regeneration in the rat sciatic crush model. Rats were randomly assigned to one of three groups of 12 animals each: (1) sham surgery and pregabalin injections; (2) crush injury and pregabalin injections; and (3) crush injury and saline vehicle injections. Nerve regeneration was evaluated with weekly walking tracks and histomorphometry. There were no significant differences in sciatic function index or histomorphometric parameters at the 21-day endpoint between the pregabalin-treated rats undergoing crush injury and the saline-treated controls. Although we have observed a subjectively improved clinical course in human patients treated with pregabalin after traumatic nerve injury, the effect does not appear to be due to accelerated nerve regeneration.