Microvascular stress analysis. Part I: simulation of microvascular anastomoses using finite element analysis

PURPOSE OF THE STUDY: To develop a finite element model (FEM) to study the effect of the stress and strain, in microvascular anastomoses that result from the geometrical mismatch of anastomosed vessels. MATERIAL AND METHODS: FEMs of end-to-end and end-to-side anastomoses were constructed. Simulations were made using finite element software (NISA). We investigated the angle of inset in the end-to-side anastomosis and the discrepancy in the size of the opening in the vessel between the host and recipient vessels. The FEMs were used to predict principal and shear stress and strain at the position of each node. RESULTS: Two types of vascular deformation were predicted during different simulations: longitudinal distortion, and rotational distortion. Stress values ranged from 151.1 to 282.4MPa for the maximum principal stress, from -122.9 to -432.2MPa for the minimum principal stress, and from 122.1 to 333.1MPa for the maximum shear stress. The highest values were recorded when there was a 50% mismatch in the diameter of the vessels at the site of the end-to-end anastomosis. CONCLUSION: The effect of the vessel's size discrepancy on the blood flow and deformation was remarkable in the end-to-end anastomosis. End-to-side anastomosis was superior to end-to-end anastomosis. FEM is a powerful tool to study vascular deformation, as it predicts deformation and biomechanical processes at sites where physical measurements are likely to remain impossible in living humans.     

Engineering antigen-specific primary human NK cells against HER-2 positive carcinomas

NK cells are promising effectors for tumor adoptive immunotherapy, particularly when considering the targeting of MHC class I low or negative tumors. Yet, NK cells cannot respond to many tumors, which is particularly the case for nonhematopoietic tumors such as carcinomas or melanoma even when these cells lose MHC class I surface expression. Therefore, we targeted primary human NK cells by gene transfer of an activating chimeric receptor specific for HER-2, which is frequently overexpressed on carcinomas. We found that these targeted NK cells were specifically activated upon recognition of all evaluated HER-2 positive tumor cells, including autologous targets, as indicated by high levels of cytokine secretion as well as degranulation. The magnitude of this specific response correlated with the level of HER-2 expression on the tumor cells. Finally, these receptor transduced NK cells, but not their mock transduced counterpart, efficiently eradicated tumor cells in RAG2 knockout mice as visualized by in vivo imaging. Taken together, these results indicate that the expression of this activating receptor overrides inhibitory signals in primary human NK cells and directs them specifically toward HER-2 expressing tumor cells both in vitro and in vivo.     

Spinal anesthesia for elective lumbar spine surgery

Study Objective: To evaluate a large series of elective lumbar spine surgical procedures by a single surgeon whose patients were all offered spinal anesthesia.

Design: Retrospective chart review.

Setting: Tertiary-care teaching hospital.

Measurements and Main Results: The records of all elective lumbar spine procedures between 1984 and 1995 performed by one surgeon (GRB) were obtained, and 803 were identified. Of those 803 patients, 611 accepted spinal anesthesia. Data collected included patient demographics, details of the spinal and general anesthesia, perioperative complications, and impact of the spinal anesthetic options on the outcome of spinal anesthesia. General and spinal anesthesia patients were comparable for age, gender, height, and ASA physical status. Patients who received spinal anesthesia were significantly heavier than the general anesthesia patients. Among perioperative complications, nausea and deep venous thrombosis occurred significantly more often in the general than spinal anesthesia patients. Mild hypotension and decreased heart rate (HR) were the most common hemodynamic changes with spinal anesthesia, whereas hypertension and increased HR were the result of general anesthesia. Among spinal anesthetic drugs, plain bupivacaine was associated with the lowest incidence of supplemental local anesthetic use intraoperatively compared to hyperbaric bupivacaine or hyperbaric tetracaine.

Conclusion: Spinal anesthesia is an effective alternative to general anesthesia for lumbar spine surgery and has a reduced rate of minor complications.     

One-stage zygomaticomandibular approach for improved access to the hemimaxilla and the middle base of the skull

In this report, we describe a 1-stage zygomaticomandibular composite flap for improved access to the retromaxillary space and the base of the skull. The zygoma and the mandible were not detached from the facial musculature or from its overlying tissues, maintaining an optimum bone-soft tissue relationship. The advantage of this approach was the enhanced exposure of the deep lesion, which provided a shorter and wider view to the maxilla, the retromaxillary space, and the base of the skull. Restoration of the skeletal symmetry and the three-dimensional contour of the maxilla was greatly enhanced by using preadapted plates and a stereolithographic model. To the best of our knowledge, no references were found in the literature regarding the use of the same technique for treating defects of similar nature to those described in this article. The deep circumflex iliac artery flap was used to reconstruct the midfacial defect and the base of the skull. The use of the flap provided optimum results because the defect was closed with the muscle that became epithelialized with minimal bulk.     

A model for international nursing collaboration

This article describes arguments for the development of a model for exchange of experiences among nurses, nurse managers, and nurse educators from two countries based on theories of reflection and practice and Freire's theory of dialogical action and its characteristics. The collaboration focused on exchange of experiences within nursing practice, leadership and management, and nursing education. The model consists of several activities: careful selection of participants in the exchange program; participants' observations and studies of caring in nursing practice in the other culture; keeping a diary about one's own reflections, thoughts, and questions; and participation in reflective dialogue and meetings with colleagues. The model included selection and implementation of a subject and written assignments for planned change in nursing practice within participants' own clinical nursing setting. After an implementation period of 6 months to 1 year, the outcome of the implemented change was reported in seminars and workshops.     

Curcumin suppresses constitutive activation of nuclear factor-kappa B and requires functional Bax to induce apoptosis in Burkitt's lymphoma cell lines

We provide evidence that curcumin, a natural compound isolated from rhizomes of plant Curcuma longa, induces apoptosis in several Burkitt's lymphoma cell lines expressing Bax protein (AS283A, KK124, and Pa682PB), whereas it has no effects in cell lines with no Bax expression (BML895 and CA46). Our data show that curcumin treatment results in down-regulation of constitutive activation of nuclear factor-kappaB (NF-kappaB) via generation of reactive oxygen species where it causes conformational changes in Bax protein leading to loss of mitochondrial membrane potential and release of cytochrome c to the cytosol. This leads to activation of caspase-9, caspase-3, and poly(ADP)-ribose polymerase cleavage leading to caspase-dependent apoptosis. In addition, curcumin treatment of Burkitt's lymphoma cell lines also causes up-regulation of DR5; however, this up-regulation does not result in apoptosis. Importantly, cotreatment with curcumin and TRAIL induces apoptosis in Bax-deficient cell lines. Taken together, our findings suggest that curcumin is able to induce apoptosis in Bax-positive cell lines, whereas combinations with TRAIL result in apoptosis in Bax-negative cell lines. These findings also raise the possibility that incorporation of curcumin in treatment regimens may provide a novel approach for the treatment of Burkitt's lymphomas and provide the molecular basis for such future translational efforts.     

Long-term compliance with bladder management in patients with spinal cord injury: A Saudi-Arabian perspective

Objective: To examine long-term compliance with bladder management in patients with spinal cord injury (SCI) at a tertiary care rehabilitation facility in Saudi Arabia.

Design: Cross-sectional survey.

Setting: Tertiary care rehabilitation facility in Saudi Arabia.

Participants: A self-administered questionnaire was distributed to patients with SCI during their clinic visits. 50 patients (41 males and nine females) participated in the survey. Data documentation included demographic characteristics, type and level of injury, compliance with bladder management and barriers in compliance.

Main outcome measures: The type of bladder management employed at first follow-up visit was compared with that employed at discharge.

Results: Eleven out of 41 patients who were discharged on clean intermittent catheterization (CIC) stopped it within 3 months of discharge, mainly due to lack of accessibility and financial support to buy catheters. Of the total sample, 23% reported that they did not know the difference between catheter types and their advantages, and 49% stated that they did not receive proper health education regarding bladder management.

Conclusion: CIC was the most commonly used bladder management technique in patients with SCI following up at a tertiary care rehabilitation facility in Saudi Arabia. Compliance with CIC may be improved by ensuring access to catheters post-discharge and by providing appropriate education about bladder management during inpatient rehabilitation.     

Effectiveness and safety of generic and brand direct acting antivirals for treatment of chronic hepatitis C

BACKGROUNDDirect acting antivirals (DAAs) are a very effective treatment for hepatitis C virus (HCV). However, brand DAAs are expensive. The licensing of cheaper generic DAAs may address this issue, but there is a lack of clinical studies comparing the efficacy of generic vs brand DAA formulations. AIMTo compare the efficacy and safety of generic against brand DAAs for chronic hepatitis C treatment in Bahrain.METHODSThis was a retrospective observational study involving 289 patients with chronic HCV infection during 2016 to 2018. There were 149 patients who were treated with brand DAAs, while 140 patients were treated with generic DAAs. Commonly used DAAs were Ombitasvir/Paritaprevir/Ritonavir ± Dasabuvir ± Ribavirin, and Sofosbuvir/Daclatasvir ± Ribavirin. SVR at 12 wk post treatment was the main outcome variable.RESULTSOverall, 87 patients (30.1%) had cirrhosis and 68.2% had genotype 1 HCV infection. At 12 wk post treatment, SVR was achieved by 271 (93.8%) of the patients. In patients who were treated with generic medications, 134 (95.7%) achieved SVR at 12 wk post treatment, compared to 137 (91.9%) among those treated with brand medications (P = 0.19). Having cirrhosis [odds ratio (OR): 9.41, 95% confidence interval (CI): 2.47–35.84] and having HCV genotype 3 (OR: 3.56, 95%CI: 1.03–12.38) were significant independent predictors of not achieving SVR. Alanine transaminase, gamma-glutamyl transpeptidase, and total bilirubin levels decreased significantly following therapy with both generic and brand DAAs.CONCLUSIONGeneric and brand DAAs demonstrate comparable effectiveness in the treatment of chronic hepatitis C patients. Both are safe and equally effective in improving biochemical markers of hepatic inflammation.