[Research progress on exosomes and exosomal microRNAs in the occurrence and development of diabetic peripheral neuropathy].

Diabetic peripheral neuropathy (DPN) is one of the chronic complications of diabetic neuropathy, and also the main cause of chronic wounds and disability. Exosomes and exosomal-microRNAs (miRNAs) are closely related to DPN and participate in the signal transduction and protein expression of the peripheral nervous system by mediating intercellular communication. However, the specific role and mechanism of EVs and exosomal-miRNAs in the occurrence and development of DPN in high-glucose environments are not fully understood. This article reviews the promotion of EVs and exosomal-miRNAs in the occurrence and development of DPN in inhibiting axon growth, promoting inflammatory response, and inducing vascular injury in a high glucose environment.

[Research progress of Eubacterium and its metabolite short-chain fatty acids in regulating type 2 diabetes mellitus].

Intestinal flora and its metabolites are closely related to the progression of type 2 diabetes mellitus(T2DM). Eubacterium is one of the dominant intestinal flora, and its metabolites short-chain fatty acids (SCFAs) play a leading role in regulating intestinal metabolic balance. It has been reported that SCFAs can regulate the secretion of glucagon-like peptide-1, improve the function of pancreatic ß cells, participate in bile acids metabolism and regulate the production of inflammatory factors in T2DM. Based on the above research background, this article mainly reviews the relationship between Eubacterium and its metabolite SCFAs and T2DM and its regulatory mechanism.

[A study of the clinical curative effect of nucleos(t)ide analogues treated to pegylated interferon-α add-on therapy in patients with chronic hepatitis B].

Objective: To investigate the hepatitis B surface antigen (HBsAg) clearance condition and its predictive factors after treatment with nucleos(t)ide analogues to pegylated interferon-α add-on therapy in patients with chronic hepatitis B. Methods: Patients with chronic hepatitis B who visited the First Affiliated Hospital of Zhengzhou University from 2018~2019 were prospectively enrolled. HBsAg≤ 1500 IU/mL, hepatitis B e antigen-negative, HBV DNA undetectable, received antiviral treatment with nucleos(t)ide analogues for at least one year, and pegylated interferon-α add-on therapy for 48 weeks were included. The primary endpoint of study was to determine the proportion of HBsAg clearance at 72 weeks. Concurrently, the predictive factors for HBsAg clearance were analyzed. Quantitative and qualitative data were analyzed using a t-test or non-parametric test and a Fisher's exact test. Results: A total of 38 cases were included in this study, of which 13 cases obtained HBsAg clearance at 48 weeks of therapy and another six cases obtained HBsAg clearance throughout the extended treatment period of 72 weeks, accounting for 50.00% of all enrolled patients. There was a significant difference in HBsAg dynamics between the HBsAg clearance group and the non-clearance group (P < 0.05). Univariate logistic regression analysis showed that patients' age, baseline, 12-and 24-week HBsAg levels, and early HBsAg reduction were predictive factors for HBsAg clearance at 72 weeks of treatment. Multivariate logistic regression analysis showed that age (OR = 1.311; P = 0.016; 95% confidence interval: 1.051~1.635) and HBsAg levels at 24 weeks of treatment (OR = 4.481; P = 0.004; 95% confidence interval: 1.634~12.290) were independent predictors for HBsAg clearance. Conclusion: Hepatitis B e antigen-negative, nucleos(t)ide analogue treated, HBsAg ≤ 1500 IU/mL, and HBV DNA undetectable, peg-IFNα add-on treatment for 48 weeks could promote HBsAg clearance in patients with chronic hepatitis B. Six of the sixteen cases (37.50%) who did not obtain HBsAg clearance at week 48 did so with the course of therapy extended to week 72. Hence, the optimal individualized treatment strategy should be customized according to the predictors rather than the fixed 48-week course. Age (≤ 38), baseline HBsAg level (≤2.86 log(10)IU/ml), HBsAg level at 24 weeks (≤ 0.92 log(10)IU/ml), and 12-week HBsAg decrease from baseline (≥ 0.67 log(10)IU/ml) indicate that patients are highly likely to obtain HBsAg clearance at the 72 weeks of combination therapy, in which the combined indicator based on HBsAg level ≤0.92 log(10)IU/ml at 24 weeks will identify 85.0% to 100.0% of patients with HBsAg clearance.

[Prediction of severe outcomes of patients with COVID-19].

Objective: To establish a new model for the prediction of severe outcomes of COVID-19 patients and provide more comprehensive, accurate and timely indicators for the early identification of severe COVID-19 patients. Methods: Based on the patients' admission detection indicators, mild or severe status of COVID-19, and dynamic changes in admission indicators (the differences between indicators of two measurements) and other input variables, XGBoost method was applied to establish a prediction model to evaluate the risk of severe outcomes of the COVID-19 patients after admission. Follow up was done for the selected patients from admission to discharge, and their outcomes were observed to evaluate the predicted results of this model. Results: In the training set of 100 COVID-19 patients, six predictors with higher scores were screened and a prediction model was established. The high-risk range of the predictor variables was calculated as: blood oxygen saturation <94%, peripheral white blood cells count >8.0×10(9), change in systolic blood pressure <-2.5 mmHg, heart rate >90 beats/min, multiple small patchy shadows, age >30 years, and change in heart rate <12.5 beats/min. The prediction sensitivity of the model based on the training set was 61.7%, and the missed diagnosis rate was 38.3%. The prediction sensitivity of the model based on the test set was 75.0%, and the missed diagnosis rate was 25.0%. Conclusions: Compared with the traditional prediction (i.e. using indicators from the first test at admission and the critical admission conditions to assess whether patients are in mild or severe status), the new model's prediction additionally takes into account of the baseline physiological indicators and dynamic changes of COVID-19 patients, so it can predict the risk of severe outcomes in COVID-19 patients more comprehensively and accurately to reduce the missed diagnosis of severe COVID-19.

[Oncologic outcomes of early stage cervical cancer performed operation by different laparoscopic surgical procedures: analysis of clinical data from mutiple centers].

Objective: To evaluate the oncologic outcomes of different laparoscopic radical hysterectomy. Methods: From January 2011 to December 2014, the laparoscopic operation cases of cervical cancer at stage Ⅰb1, Ⅰb2, Ⅱa1 and Ⅱa2, including the histologic subtypes of squamous-cell carcinoma, adenocarcinoma and adenosquamous carcinoma, were collected in five clinical centers. The data were divided into two groups according to the surgical procedures, that is, modified laparoscopic-vaginal radical hysterectomy (mLVRH) and total laparoscopic radical hysterectomy (TLRH). The overall survival rate (OS), disease-free survival rate (DFS) at 5 years were retrospectively analyzed in this study. Results: There were 674 cases in total, including 377 cases of mLVRH, 297 cases of TLRH. (1) The OS at 5 years: the mLVRH was 96.1% and the TLRH was 92.0%, and the mLVRH was higher than that of TLRH （P=0.010）. Stratify analysis， including stage of disease （Ⅰb1 and Ⅱa1）， histologic subtypes （squamous-cell carcinoma, adenocarcinoma）， lymph node metastasis， revealed that, ① Stage of disease: in stage Ⅰb1, the OS at five years of mLVRH was higher than that in TLRH group （98.6% vs 93.6%, P=0.012）. In stage Ⅱa1, there was significant difference between the two groups, the OS at five years of mLVRH and TLRH were 93.6% and 77.6% （P=0.007）. ② Histologic subtypes: for the OS at five years of squamous-cell carcinoma, mLVRH and TLRH were 96.1% and 92.3%, and there was significant difference （P=0.046）； for adenocarcinoma, the OS at five years were 91.0% and 88.6%， and there was no difference between two groups （P=0.230）. ③ Lymph node metastasis： the mLVRH and TLRH with lymph node metastasis, the OS at five years were 98.6% and 96.4%; the mLVRH and TLRH without lymph node metastasis, the OS at five years were 89.3% and 80.8%. There were no significant differences between the two groups,respectively (P=0.156， P=0.093）. (2) The DFS at 5 years: there was no significant difference between mLVRH and TLRH (94.1% vs 90.9%, P=0.220). Stratify analysis for stage of disease, the mLVRH group was higher than that in the TLRH group in stage Ⅰb1 (97.0% vs 92.8%, P=0.039). However, for stage Ⅱa1, there was no significant difference between mLVRH and TLRH group （88.2% vs 75.8%, P=0.074）. Conclusions: The results of this retrospective study indicated that different laparoscopy surgical procedures had diverse oncologic outcomes. The OS at 5 years of the mLVRH is superior to the TLRH. The DFS at 5 years in Ⅰb1 stage, the mLVRH is higher than the TLRH. Therefore, the modified laparoscopy is still an alternative surgery for early cervical cancer patients when following the principle of no-tumor-exposure.

[Analysis of the therapeutic effects of different treatment modalities on the outcomes of 87 patients with lung oligometastasis from nasopharyngeal carcinoma after radiotherapy].

OBJECTIVE: The aim of the present study was to evaluate the efficacy of three different modalities in treatment of lung oligometastases from nasopharyngeal carcinoma (NPC) after radiotherapy and to identify a more appropriate treatment modality. METHODS: The clinical data of 87 cases of lung oligometastases from NPC were analyzed retrospectively. Among them, 33 patients underwent local small-field irradiation+ /- chemotherapy, 28 underwent whole-lung irradiation+ chemotherapy, and 26 underwent simple chemotherapy. The survival rates were calculated using Kaplan-Meier analysis. The differences among the modalities were evaluated using the log-rank test. Cox univariate and multivariate analyses were performed to determine the influencing factors. RESULTS: The 3-year lung metastasis survival (LMS) rates of patients with lung metastasis undergoing the three treatment modalities (local small-field irradiation+ /-chemotherapy, whole-lung irradiation+ chemotherapy and chemotherapy alone) were 89.3%, 72.7%, and 72.4%, respectively, showing a significant difference between the groups (P=0.003). Further subgroup analysis showed that the 5-year LMS rate was significantly higher in the local small-field irradiation+ /-chemotherapy group than that in the whole-lung irradiation+ chemotherapy group and chemotherapy alone group (P=0.001). The 2-year progression-free survival (PFS) rates of the three groups were 57.1%, 25.8% and 3.8%, respectively, showing significant intergroup differences (P=0.002 and P<0.001). Multivariate analysis indicated that compared with the whole lung irradiation group and the chemotherapy alone group, the local irradiation+ /- chemotherapy is an independent favorable prognostic factor for LMS and PFS (P<0.05). CONCLUSION: Local radiotherapy combined with systemic chemotherapy is the best therapeutic modality for lung oligometastases derived from NPC after radiotherapy, improving the LMS and prolonging the PFS.

Polymorphic phase transition mechanism of compressed coesite.

Silicon dioxide is one of the most abundant natural compounds. Polymorphs of SiO2 and their phase transitions have long been a focus of great interest and intense theoretical and experimental pursuits. Here, compressing single-crystal coesite SiO2 under hydrostatic pressures of 26-53 GPa at room temperature, we discover a new polymorphic phase transition mechanism of coesite to post-stishovite, by means of single-crystal synchrotron X-ray diffraction experiment and first-principles computational modelling. The transition features the formation of multiple previously unknown triclinic phases of SiO2 on the transition pathway as structural intermediates. Coexistence of the low-symmetry phases results in extensive splitting of the original coesite X-ray diffraction peaks that appear as dramatic peak broadening and weakening, resembling an amorphous material. This work sheds light on the long-debated pressure-induced amorphization phenomenon of SiO2, but also provides new insights into the densification mechanism of tetrahedrally bonded structures common in nature.

First-order liquid-liquid phase transition in cerium.

We report the first experimental observation of a liquid-liquid phase transition in the monatomic liquid metal cerium, by means of in situ high-pressure high-temperature x-ray diffraction experiments. At 13 GPa, upon increasing temperature from 1550 to 1900 K high-density liquid transforms to a low-density liquid, with a density difference of 14%. Theoretic models based on ab initio calculations are built to investigate the observed phase behavior of the liquids at various pressures. The results suggest that the transition primarily originates from the delocalization of f electrons and is deemed to be of the first order that terminates at a critical point.

Potential role of proteomics in the diagnosis of lymphoma: a meta-analysis.

Surface-enhanced laser desorption/ionisation time-of-flight mass spectrometry (SELDI-TOF-MS) has been approved for identifying biomarkers and diagnosing many diseases such as lymphomas. It is arguable whether the SELDI technique has its value of diagnostic accuracy for lymphomas. The purpose of our study is to determine the diagnostic accuracy of SELDI-TOF-MS for diagnosing lymphomas. The Cochrane Central Register of Controlled Trials, MEDLINE, Pub Med, EMBASE, the Chinese Biomedical Literature Database, the China Academic Journals Full-text Database, and the Chinese Scientific Journals Database were searched systematically for potential studies. Reference lists of included studies and review articles were also reviewed. All studies that reported data on patients with a confirmed diagnosis of lymphomas and that compared the measurement of SELDI-TOF-MS with pathology standard were considered for inclusion. Eleven studies were included in the systematic review. The ranges of the diagnostic value of SELDI-TOF-MS for lymphoma were as follows: sensitivity (SEN) was 0.69-0.96; specificity (SPE) was 0.70-1.00; positive likelihood ratio (PLR) was 2.99-96.09; negative likelihood ratio (NLR) was 0.04-0.35; and diagnostic odds ratio (DOR) was 18.13-1250.71, respectively. Further, we analysed serum samples as a subgroup, and the pooled endpoints were as follows: pooled SEN was 0.89 (0.85-0.91); pooled SPE was 0.91 (0.88-0.93); pooled PLR was 12.35 (5.36-28.44); pooled NLR was 0.13 (0.09-0.20); and pooled DOR was 101.04 (39.57-258.04), respectively. SELDI-TOF-MS showed high accuracy in identifying lymphoma and could be a useful screening tool for diagnosing lymphoma patients.

Inhibition of ß-catenin signaling by nongenomic action of orphan nuclear receptor Nur77.

Dysregulation of ß-catenin turnover due to mutations of its regulatory proteins including adenomatous polyposis coli (APC) and p53 is implicated in the pathogenesis of cancer. Thus, intensive effort is being made to search for alternative approaches to reduce abnormally activated ß-catenin in cancer cells. Nur77, an orphan member of the nuclear receptor superfamily, has a role in the growth and apoptosis of cancer cells. Here, we reported that Nur77 could inhibit transcriptional activity of ß-catenin by inducing ß-catenin degradation via proteasomal degradation pathway that is glycogen synthase kinase 3ß and Siah-1 independent. Nur77 induction of ß-catenin degradation required both the N-terminal region of Nur77, which was involved in Nur77 ubiquitination, and the C-terminal region, which was responsible for ß-catenin binding. Nur77/ΔDBD, a Nur77 mutant lacking its DNA-binding domain, resided in the cytoplasm, interacted with ß-catenin, and induced ß-catenin degradation, demonstrating that Nur77-mediated ß-catenin degradation was independent of its DNA binding and transactivation, and might occur in the cytoplasm. In addition, we reported our identification of two digitalis-like compounds (DLCs), H-9 and ATE-i2-b4, which potently induced Nur77 expression and ß-catenin degradation in SW620 colon cancer cells expressing mutant APC protein in vitro and in animals. DLC-induced Nur77 protein was mainly found in the cytoplasm, and inhibition of Nur77 nuclear export by the CRM1-dependent nuclear export inhibitor leptomycin B or Jun N-terminal kinase inhibitor prevented the effect of DLC on inducing ß-catenin degradation. Together, our results demonstrate that ß-catenin can be degraded by cytoplasmic Nur77 through their interaction and identify H-9 and ATE-i2-b4 as potent activators of the Nur77-mediated pathway for ß-catenin degradation.

Diverse cyclization catalyzed by In(OTf)3 for the convergent assembly of substituted tetrahydrofurans and tetrahydropyrans.

[reaction: see text]. A novel In(OTf)3-catalyzed (3,5) oxonium-ene type cyclization for the facile construction of various multisubstituted tetrahydrofurans and tetrahydropyrans was successfully developed. Further mechanistic investigations unveiled an In(OTf)3-catalyzed skeletal reorganization of the tetrahydrofuran to its thermodynamic isomer under thermal conditions.

Synthetic studies toward anisatin: a formal synthesis of (+/-)-8-deoxyanisatin.

[figure: see text] An efficient strategy to construct the congested C-7a quaternary chiral center of anisatin was developed, by way of an Eschenmoser-Claisen rearrangement. Conversion of the resultant amide to Kende's epsilon-lactone intermediate 3 in four steps completed a concise formal synthesis of (+/-)-8-deoxyanisatin (2).

Prevention of ischemia-reperfusion injury in a rat skin flap model: the role of mast cells, cromolyn sodium, and histamine receptor blockade.

The objective of this study was to examine the role of mast cells and their principal product, histamine, in ischemia/reperfusion injury. Cromolyn sodium, diphenhydramine, and cimetidine were administered to ischemic flaps just before reperfusion and evaluated for flap survival, mast cell count, neutrophil count, and myeloperoxidase levels. Epigastric island skin flaps were elevated in 49 rats; they were rendered ischemic by clamping the artery for 10 hours. Thirty minutes before reperfusion, the rats were treated with intraperitoneal saline (n = 11), cimetidine (n = 11), diphenhydramine (n = 11), or cromolyn sodium (n = 10). Flap survival was evaluated at 7 days. Neutrophil counts, mast cell counts, and myeloperoxidase levels were evaluated 12 hours after reperfusion. Flap necrosis in the sham group of animals (n = 6) was 0.0 percent, as expected, whereas the control group (saline-treated animals) had 47.3+/-33.4 percent necrosis. Animals treated with diphenhydramine and cimetidine demonstrated a significant decrease in flap necrosis to 17.7+/-8.8 percent and 19.4+/-14.7 percent, respectively. This protective effect was not seen with cromolyn sodium (44.3+/-35.6 percent). Both neutrophil and mast cell counts were significantly decreased in flaps from antihistamine-treated and sham animals versus both saline- and cromolyn sodium-treated groups. The administration of diphenhydramine and cimetidine before reperfusion can significantly reduce the extent of flap necrosis and the neutrophil and mast cell counts caused by ischemia/reperfusion. This protective effect is not seen with cromolyn sodium. The protective effect of antihistamines on flap necrosis might be related to the decrease in neutrophils and, possibly, mast cells within the flap.

Reconstruction of the mandible with osseous free flaps: a 10-year experience with 150 consecutive patients.

Osseous free flaps have become the preferred method for reconstructing segmental mandibular defects. Of 457 head and neck free flaps, 150 osseous mandible reconstructions were performed over a 10-year period. This experience was retrospectively reviewed to establish an approach to osseous free flap mandible reconstruction. There were 94 male and 56 female patients (mean age, 50 years; range 3 to 79 years); 43 percent had hemimandibular defects, and the rest had central, lateral, or a combination defect. Donor sites included the fibula (90 percent), radius (4 percent), scapula (4 percent), and ilium (2 percent). Rigid fixation (up to five osteotomy sites) was used in 98 percent of patients. Aesthetic and functional results were evaluated a minimum of 6 months postoperatively. The free flap success rate was 100 percent, and bony union was achieved in 97 percent of the osteotomy sites. Osseointegrated dental implants were placed in 20 patients. A return to an unrestricted diet was achieved in 45 percent of patients; 45 percent returned to a soft diet, and 5 percent were on a liquid diet. Five percent of patients required enteral feeding to maintain weight. Speech was assessed as normal (36 percent), near normal (27 percent), intelligible (28 percent), or unintelligible (9 percent). Aesthetic outcome was judged as excellent (32 percent), good (27 percent), fair (27 percent), or poor (14 percent). This study demonstrates a very high success rate, with good-to-excellent functional and aesthetic results using osseous free flaps for primary mandible reconstruction. The fibula donor site should be the first choice for most cases, particularly those with anterior or large bony defects requiring multiple osteotomies. Use of alternative donor sites (i.e., radius and scapula) is best reserved for cases with large soft-tissue and minimal bone requirements. The ilium is recommended only when other options are unavailable. Thoughtful flap selection and design should supplant the need for multiple, simultaneous free flaps and vein grafting in most cases.

The timing and nature of neovascularization of jejunal free flaps: an experimental study in a large animal model.

The present study was designed (1) to determine whether a free jejunal transfer in a large animal model can develop collateral circulation that is adequate to maintain viability after division of the pedicle and (2) to determine the earliest time pedicle ligation is safe after transplantation. A 15-cm jejunal segment was transferred to the necks of 18 dogs weighing 25 to 35 kg. The bowel segment was inset longitudinally under the skin on one side of the neck, partially covered by the neck muscles, and the mesenteric vessels were anastomosed to recipient vessels in the neck. The proximal and distal bowel stomas were exteriorized through skin openings 12 cm apart and matured. The dogs were subjected to ligation of the vascular pedicle at different intervals: postoperative day 7 (group I, n = 3), day 14 (group II, n = 5), day 21 (group III, n = 5), and day 28 (group IV, n = 5). Blood perfusion was measured in the proximal and distal bowel stomas before pedicle division (control) and 24 hours later using hydrogen gas clearance and fluorescein dye. Bowel necrosis was analyzed using planimetry. The bowel was also stained with hematoxylin and eosin and factor VIII, and new blood vessels were counted. Mean values (+/- standard deviation) were compared with control values for each test and with normal values in the intact bowel using analysis of variance with Neumann-Keuls post-hoc test for multiple comparisons. No jejunal free flaps survived when the vascular pedicle was divided 1 week postoperatively. Bowel survival was 60 percent at 2 weeks, 83 percent at 3 weeks, and 100 percent at 4 weeks. Hydrogen gas clearance values (ml/min/100 g) were 49.6 +/- 8.7 in the mucosa of the intraabdominal jejunum and 37.9 +/- 9.4 in the jejunum that was transferred to the neck before division of the pedicle. Twenty-four hours after pedicle division, hydrogen gas clearance values were 2.8 +/- 6.4 in group I (p < 0.05), 22.4 +/- 12.4 in group II, 23.9 +/- 9.3 in group III, and 34.2 +/- 7.5 in group IV. FluoroScan readings in the transferred jejunum were 201 +/- 7.2 in the control group, 9.3 +/- 2.8 in group I (p < 0.05), 79.1 +/- 10.6 in group II, 66.2 +/- 7.3 in group III, and 164 +/- 11.9 in group IV. New vessel formation as identified by factor VIII staining correlated with increasing bowel perfusion and flap survival rate. Bowel neovascularization, perfusion, and survival increased progressively 1 week after transfer. Significant portions of the transferred bowel will neovascularize and survive as early as 2 weeks postoperatively. However, a minimum of 4 weeks before ligation of the pedicle is necessary to maximize flap perfusion and guarantee survival.

Use of a nitric oxide precursor to protect pig myocutaneous flaps from ischemia-reperfusion injury.

Nitric oxide is a radical with vasodilating properties that protects tissues from neutrophil-mediated ischemia-reperfusion injury in the heart and intestine. Previous studies in our laboratory suggested that L-arginine, a nitric oxide precursor, can protect skin flaps from ischemia-reperfusion injury. In this study, we examined the effects of L-arginine on the survival of myocutaneous flaps in a large animal model and established whether this effect was mediated by nitric oxide and neutrophils. Two superiorly based 15 x 7.5 cm epigastric myocutaneous island flaps were dissected in 15 Yorkshire pigs weighing 45 to 50 kg. One of the flaps was subjected to 6 hours of arterial ischemia and then reperfused for 4 hours (ischemia-reperfusion flaps), whereas the other flap was used as a non-ischemic control (non-ischemia-reperfusion flaps). The flaps were divided into four groups: control non-ischemia-reperfusion flaps that received only saline (group I); ischemia-reperfusion flaps that were treated with saline (group II); and flaps treated with either L-arginine (group III) or Nomega-nitro-L-arginine methylester (L-NAME), a nitric oxide synthase competitive inhibitor, plus L-arginine in equimolar amounts (group IV). These drugs were administered as an intravenous bolus 10 minutes before the onset of reperfusion, followed by a 1-hour continuous intravenous infusion. Full-thickness muscle biopsies were taken at baseline, 3 and 6 hours of ischemia, and 1 and 4 hours of reperfusion. The biopsies were evaluated by counting neutrophils and measuring myelo-peroxidase activity. At the end of the experiment, skeletal muscle necrosis was quantified using the nitroblue tetrazolium staining technique, and a full-thickness biopsy of each flap was used for determination of water content. Statistical analysis was performed using analysis of variance and the Newman-Keuls test. Non-ischemia-reperfusion flaps showed no muscle necrosis. Ischemia-reperfusion flaps treated with saline had 68.7 +/- 9.1 percent necrosis, which was reduced to 21.9 +/- 13.6 percent with L-arginine (p < 0.05). L-NAME administered concomitantly with L-arginine demonstrated a necrosis rate similar to that of saline-treated ischemia-reperfusion flaps (61.0 +/- 17.6 percent). Neutrophil counts and myeloperoxidase activity after 4 hours of reperfusion were significantly higher in ischemia-reperfusion flaps treated with L-NAME and L-arginine as compared with the other three groups (p < 0.05). Flap water content increased significantly in ischemia-reperfusion flaps treated with saline and L-NAME plus L-arginine versus non-ischemia-reperfusion flaps (p < 0.02) and L-arginine-treated ischemia-reperfusion flaps (p < 0.05). There was no difference in flap water content between ischemia-reperfusion flaps treated with L-arginine and non-ischemia-reperfusion flaps. Administration of L-arginine before and during the initial hour of reperfusion significantly reduced the extent of flap necrosis, neutrophil accumulation, and edema due to ischemia-reperfusion injury in a large animal model. This protective effect is completely negated by the use of the nitric oxide synthase blocker L-NAME. The mechanism of action seems to be related to nitric oxide-mediated suppression of ischemia-reperfusion injury through neutrophil activity inhibition.

A review of 716 consecutive free flaps for oncologic surgical defects: refinement in donor-site selection and technique.

Free-tissue transfer has become an important method for reconstructing complex oncologic surgical defects. This study is a retrospective review of a 10-year experience with 716 consecutive free flaps in 698 patients. Regional applications included the head and neck (69 percent), trunk and breast (14 percent), lower extremity (12 percent), and upper extremity (5 percent). Donor sites included the rectus abdominis (195), fibula (193), forearm (133), latissimus dorsi (69),jejunum (55), gluteus (28), scapula (26), and seven others (17). Microvascular anastomoses were performed to large-caliber recipient vessels using a continuous suture technique; end-to-end anastomoses were preferred (75 percent). Flaps were designed to avoid the need for vein grafts. Conventional postoperative flap monitoring methods were used. These included clinical observation supplemented by Doppler ultrasonography, surface temperature probes, and pin prick testing. Buried flaps were either evaluated with Doppler ultrasonography or not monitored. The overall success rate for free-flap reconstruction of oncologic surgical defects was 98 percent. Fifty-seven flaps (8 percent) were reexplored for either anastomotic or infectious problems. Reexplored flaps were salvaged in 40 cases (70 percent). Surviving flaps resulted in a healed wound and did not delay postoperative radiation or chemotherapy. The incidence of major and minor postoperative complications was 34 percent. The mean duration of hospitalization was 20 days, and the average cost was $40,224. The results of this study support the need for only seven donor sites to solve the majority (98 percent) of oncologic problems requiring microsurgical expertise. The evolution of preferred donor sites for specific regional applications is illustrated in this 10-year experience. Technical refinements have simplified performing the microsurgical anastomoses and essentially eliminated the need for vein grafts. Conventional monitoring has led to the rapid identification of vascular compromise and subsequent flap salvage in the majority of non-buried free flaps.

The protective effect of L-arginine on ischemia-reperfusion injury in rat skin flaps.

The objective of this study was to examine whether the administration of L-arginine, a precursor of nitric oxide and substrate of nitric oxide synthase, prior to reperfusion could lead to decrease in neutrophil-mediated tissue injury and improved flap survival. Epigastric island skin flaps were elevated in 70 rats and rendered ischemic. Thirty minutes prior to reperfusion, the rats were treated with intraperitoneal saline (n = 15), L-arginine (n = 15), D-arginine (n = 15), or N omega-nitro-L-arginine methylester plus L-arginine in equimolar amounts (n = 15). Flap survival at 7 days and neutrophil counts at 24 hours were evaluated. Flap necrosis as expected in the sham group of animals (n = 10) was 0.0 percent, while the control (saline-treated) animals had 59.6 percent necrosis. Animals treated with L-arginine demonstrated a significant decrease in flap necrosis to 12.7 percent. This protective effect was almost completely negated by N omega-nitrol-L-arginine methylester, which significantly increased flap necrosis to 49.3 percent and was much less pronounced with D-arginine (28.6 percent). Neutrophil counts were significantly decreased in flaps from L-arginine-treated and sham animals versus both saline and N omega-nitro-L-arginine methylester-treated groups. We conclude that administration of L-arginine prior to reperfusion can significantly reduce the extent of flap necrosis and flap neutrophil counts due to ischemia-reperfusion injury. This protective effect is completely negated by nitric oxide synthase inhibition. Since L-arginine reduces the number of neutrophils within the flap and the extent of flap necrosis only in the presence of active nitric oxide synthase, we hypothesize that this protective effect of L-arginine on ischemia-reperfusion injury is secondary to a nitric oxide-mediated suppression of neutrophil-mediated injury.

Effects of vasoactive medications on the blood flow of island musculocutaneous flaps in swine.

Pedicled flaps and microsurgical free tissue transfers are increasingly being used for reconstruction in the elderly and poorer risk patient. The use of systemically administered vasoactive agents to date has been avoided because of the fear that systemic levels of these agents perioperatively (particularly the vasopressors) might decrease blood flow and compromise the viability of the flap. There are no large-animal, real-time hemodynamic studies that support or disprove this belief. The objectives of this study were to (1) develop a musculocutaneous flap model in the pig that allows accurate, simultaneous monitoring of systemic and flap hemodynamic parameters such as flow and resistance and (2) identify the effects of commonly used vasoactive substances (dopamine, dobutamine, and phenylephrine) at clinically used levels on systemic and flap pressure/flow relationships. Vertically based rectus abdominis musculocutaneous flaps were raised in 8 anesthetized, 50- to 55-kg pigs, and a flow probe was placed around the artery. Catheters within the pulmonary artery and aorta were used to measure cardiac output and aortic root pressures. Measures of arterial blood pressure, cardiac output, and musculocutaneous flap flow were obtained at baseline and during the administration of varying doses of dopamine dobutamine and phenylephrine. Cardiac output increased significantly with low and high doses of dopamine and dobutamine, but decreased with increasing doses of phenylephrine. Flap flow, on the other hand, is increased only with dobutamine but remains unchanged with dopamine despite increased cardiac output. Flap flow decreases with high doses of phenylephrine. Flap flow also decreases relative to cardiac output with both dopamine and dobutamine. We conclude that (1) phenylephrine clearly affects flap flow adversely in a large-animal musculocutaneous model and therefore should be avoided, (2) dopamine does not affect total flap flow at either low or high doses despite increasing cardiac output, (3) dobutamine increases both flap flow and cardiac output, and (4) both dopamine and dobutamine should still be used with caution because the flap flow is not equally increased relative to total cardiac output. Possible changes in systemic and flap metabolic demand induced by these vasopressor drugs may therefore still be injurious to the flaps.