Astrocyte-secreted lipocalin-2 elicits bioenergetic failure-induced neuronal death that is causally related to high fatality in a mouse model of hepatic encephalopathy.

Hepatic encephalopathy (HE) is a neurological complication arising from acute liver failure with poor prognosis and high mortality; the underlying cellular mechanisms are still wanting. We previously found that neuronal death caused by mitochondrial dysfunction in rostral ventrolateral medulla (RVLM), which leads to baroreflex dysregulation, is related to high fatality in an animal model of HE. Lipocalin-2 (Lcn2) is a secreted glycoprotein mainly released by astrocytes in the brain. We noted the presence of Lcn2 receptor (Lcn2R) in RVLM neurons and a parallel increase of Lcn2 gene in astrocytes purified from RVLM during experimental HE. Therefore, our guiding hypothesis is that Lcn2 secreted by reactive astrocytes in RVLM may underpin high fatality during HE by eliciting bioenergetic failure-induced neuronal death in this neural substrate. In this study, we first established the role of astrocyte-secreted Lcn2 in a liver toxin model of HE induced by azoxymethane (100 µg/g, ip) in C57BL/6 mice, followed by mechanistic studies in primary astrocyte and neuron cultures prepared from postnatal day 1 mouse pups. In animal study, immunoneutralization of Lcn2 reduced apoptotic cell death in RVLM, reversed defunct baroreflex-mediated vasomotor tone and prolonged survival during experimental HE. In our primary cell culture experiments, Lcn2 produced by cultured astrocytes and released into the astrocyte-conditioned medium significantly reduced cell viability of cultured neurons. Recombinant Lcn2 protein reduced cell viability, mitochondrial ATP (mitoATP) production, and pyruvate dehydrogenase (PDH) activity but enhanced the expression of pyruvate dehydrogenase kinase (PDK) 1, PDK3 and phospho-PDHA1 (inactive PDH) through MAPK/ERK pathway in cultured neurons, with all cellular actions reversed by Lcn2R knockdown. Our results suggest that astrocyte-secreted Lcn2 upregulates PDKs through MAPK/ERK pathway, which leads to reduced PDH activity and mitoATP production; the reinforced neuronal death in RVLM is causally related to baroreflex dysregulation that underlies high fatality associated with HE.

Genome sequence of PSonyx, a singleton bacteriophage infecting Corynebacterium glutamicum.

PSonyx is a newly isolated phage that infects Corynebacterium glutamicum. This siphovirus was isolated from a French pond in the south of Paris by students from Paris-Saclay University. Its 80,277-bp singleton genome carries 136 protein-coding genes and 5 tRNAs.

Expert laparoscopist performance on virtual reality simulation tasks with and without haptic features.

BACKGROUND: Virtual reality (VR) simulation for laparoscopic training is available with and without haptic feedback features. Currently, there is limited data on haptic feedback's effect on skill development. Our objective is to compare expert laparoscopists' skills characteristics using VR delivered laparoscopic tasks via haptic and nonhaptic laparoscopic surgical interfaces. METHODS: Five expert laparoscopists performed seven skills tasks on two laparoscopic simulators, one with and one without haptic features. Tasks consisted of 2-handed instrument navigation, retraction and exposure, cutting, electrosurgery, and complicated object positioning. Laparoscopists alternated platforms at default difficulty settings. Metrics included time, economy of movement, completed task elements, and errors. Progressive change in performance for the final three iterations were determined by repeated measures ANOVA. Iteration quartile means were determined and compared using paired t-tests. RESULTS: No change in performance was noted in the last three iterations for any metric. There were no significant differences between platforms on the final two quartiles for most metrics except avoidance of over-stretch error for retraction; and cutting task was significantly better with haptics on all iteration quartiles (p < 0.03). Economy of movement was significantly better with haptics for both hands for clip application (p < 0.01) and better for right hand on complex object positioning (p < 0.05). Accuracy was better with haptics for retraction and cutting (p < 0.05) and clip application (p < 0.05). CONCLUSION: Results showed higher performance in accuracy, efficient instrument motion, and avoidance of excessive traction force on selected tasks performed on VR simulator with haptic feedback compared to those performed without haptics feedback. Laparoscopic surgeons interpreted machine-generated haptic cues appropriately and resulted in better performance with VR task requirements. However, our results do not demonstrate an advantage in skills acquisition, which requires additional study.

Protective role of VEGF/VEGFR2 signaling against high fatality associated with hepatic encephalopathy via sustaining mitochondrial bioenergetics functions.

BACKGROUND: The lack of better understanding of the pathophysiology and cellular mechanisms associated with high mortality seen in hepatic encephalopathy (HE), a neurological complication arising from acute hepatic failure, remains a challenging medical issue. Clinical reports showed that the degree of baroreflex dysregulation is related to the severity of HE. Furthermore, mitochondrial dysfunction in the rostral ventrolateral medulla (RVLM), a key component of the baroreflex loop that maintains blood pressure and sympathetic vasomotor tone, is known to underpin impairment of baroreflex. Realizing that in addition to angiogenic and vasculogenic effects, by acting on its key receptor (VEGFR2), vascular endothelial growth factor (VEGF) elicits neuroprotection via maintenance of mitochondrial function, the guiding hypothesis of the present study is that the VEGF/VEGFR2 signaling plays a protective role against mitochondrial dysfunction in the RVLM to ameliorate baroreflex dysregulation that underpins the high fatality associated with HE. METHODS: Physiological, pharmacological and biochemical investigations were carried out in proof-of-concept experiments using an in vitro model of HE that involved incubation of cultured mouse hippocampal neurons with ammonium chloride. This was followed by corroboratory experiments employing a mouse model of HE, in which adult male C57BL/6 mice and VEGFR2 wild-type and heterozygous mice received an intraperitoneal injection of azoxymethane, a toxin used to induce acute hepatic failure. RESULTS: We demonstrated that VEGFR2 is present in cultured neurons, and observed that whereas recombinant VEGF protein maintained cell viability, gene-knockdown of vegfr2 enhanced the reduction of cell viability in our in vitro model of HE. In our in vivo model of HE, we found that VEGFR2 heterozygous mice exhibited shorter survival rate and time when compared to wild-type mice. In C57BL/6 mice, there was a progressive reduction in VEGFR2 mRNA and protein expression, mitochondrial membrane potential and ATP levels, alongside augmentation of apoptotic cell death in the RVLM, accompanied by a decrease in baroreflex-mediated sympathetic vasomotor tone and hypotension. Immunoneutralization of VEGF exacerbated all those biochemical and physiological events. CONCLUSIONS: Our results suggest that, acting via VEGFR2, the endogenous VEGF plays a protective role against high fatality associated with HE by amelioration of the dysregulated baroreflex-mediated sympathetic vasomotor tone through sustaining mitochondrial bioenergetics functions and eliciting antiapoptotic action in the RVLM.

Validation of a simple technique of volumetric analysis of complex incisional hernias without 3D CT scan reconstruction.

PURPOSE: Volumetric analysis is being increasingly utilized in the preoperative evaluation of complex incisional hernias. Three-dimensional (3D) reconstruction of abdominal computed tomography (CT) scan has been used to obtain surface area (SA) and volume (Vol.) measurements, while others have used simple mathematical formulas to obtain SA and Vol. estimates without 3D reconstruction. Our objective was to assess the correlation of SA and Vol. measurements and estimates of complex incisional hernias. METHODS: We conducted a retrospective agreement study of adults who underwent abdominal wall reconstruction from 2007 to 2018. Demographics, hernia characteristics, and operative data were collected from the medical record. SA and Vol. measurements were obtained after 3D CT reconstruction. Linear CT variables were obtained independently by two surgeons and SA and Vol. estimates were calculated. Because both surgeons reported similar results, only lead author values are reported in the abstract. We used Pearson's correlation coefficient (r) to assess inter-rater agreement and the agreement between SA and Vol. measurements and estimates. RESULTS: A total of 108 patients were eligible for analysis. The mean age was 57 ± 11 years and 53 (49%) were female. 42 (39%) hernias were recurrent, 10 (9%) patients had a stoma, and 9 (8%) had a history of open abdomen. The mean defect width was 11 ± 4 cm and mean defect surface area (DSA) was 150 ± 95 cm2. Inter-rater agreement of SA and Vol. estimates was high (r ≥ 0.80). There was high correlation between SA and Vol. measurements and estimates for DSA, hernia sac volume (HSV), abdominal cavity volume (ACV), and HSV/ACV ratio (r = 0.81, 0.89, 0.94 and 0.91, respectively). CONCLUSION: SA and Vol. estimates demonstrated high level of agreement with SA and Vol. measurements using 3D reconstruction. SA and Vol. estimates can be obtained using simple mathematical formulas using easily obtained linear variables negating the need for the time and effort consuming 3D reconstruction.

Neuroinflammation and Microglial Activation at Rostral Ventrolateral Medulla Underpin Cadmium-Induced Cardiovascular Dysregulation in Rats.

PURPOSE: Cadmium is a heavy metal and environmental toxicant known to act on the central cardiovascular regulatory mechanisms, and one of its brain targets is the rostral ventrolateral medulla (RVLM), a brainstem site that maintains blood pressure and sympathetic vasomotor tone. The present study assessed the hypothesis that cadmium elicits cardiovascular dysregulation by inducing neuroinflammation and microglial activation, two potential cellular mechanisms, in RVLM. METHODS: Adult male Sprague-Dawley rats were used for measuring cardiovascular responses after intravenous administration of cadmium. We further conducted real-time PCR, immunofluorescence staining, in situ determination of mitochondrial superoxide, hematoxylin and eosin staining, and enzyme-linked immunosorbent assay (ELISA) to identify cytokine and chemokine mRNA expression, microglia activation, superoxide production, and necrotic and apoptotic cell death in RVLM. RESULTS: We found animals maintained under propofol anesthesia, intravenous administration of cadmium acetate (4 mg/kg) resulted in an increase, followed by a rebound and a secondary decrease in spontaneous baroreflex-mediated sympathetic vasomotor tone, a progressive reduction in mean arterial pressure and heart rate, alongside augmentation of pro-inflammatory cytokine and chemokine in RVLM. All those cardiovascular and neuroinflammatory events were reversed by pretreatment with an anti-inflammatory drug, pentoxifylline (50 mg/kg, i.p.). There were also concurrent microglial activation, reactive oxygen species production, hypoxia, reduced blood flow, and necrotic and apoptotic cell death in RVLM. CONCLUSION: Based on these biochemical, pharmacological and morphological observations, we conclude that neuroinflammation and microglial activation at RVLM, and their downstream cellular mechanisms, causally underpin cadmium-induced cardiovascular dysregulation.

Disproportional cardiovascular depressive effects of isoflurane: Serendipitous findings from a comprehensive re-visit in mice.

Employment of anesthetics, including isoflurane, though mandatory in animal experiments, is often regarded as a major limitation because results obtained with anesthetics may be different from those obtained under a conscious state. This study re-visits two issues related to the use of isoflurane. First, does isoflurane exert depression equally on all aspects of cardiovascular functions and their regulations? Second, is the circulatory supply of oxygen to brain tissues sufficient under isoflurane anesthesia? We determined in male C57BL/6J mice the temporal effects of 1.5% (vol/vol) isoflurane on blood pressure (BP), heart rate (HR), cardiac performance, baroreflex-mediated sympathetic vasomotor tone, cardiac vagal baroreflex, functional connectivity within the baroreflex neural circuits, carotid or cerebral blood flow, cortical tissue oxygen level, respiratory rate and blood gas. Over 150 min after exposure to 1.5% isoflurane, BP and HR were sustained at 71% and 79% of their awake levels amid a trend of progressive increase. Cardiac performance was within physiological ranges. Baroreflex-mediated sympathetic vasomotor tone gradually reversed from an 85% reduction toward the conscious level, alongside a parallel decrease in inhibitory connectivity between nucleus tractus solitarii (NTS) and rostral ventrolateral medulla. A decline in excitatory connectivity between NTS and nucleus ambiguus accompanied the decrease in cardiac vagal baroreflex. There were progressive increases in carotid or cerebral blood flow and tissue oxygen tension in cerebral cortex, alongside gradual hypoventilation, mild respiratory acidosis and hypercapnia. We conclude that, by eliciting disproportional depressive actions on cardiovascular functions and their regulations, which sustain circulatory supply of oxygen to brain tissues, 1.5% isoflurane is sufficient to maintain optimal cardiovascular functions in mice.

Redox-active DJ-1 sustains brainstem cardiovascular regulation via maintenance of mitochondrial function during mevinphos intoxication.

DJ-1 (also known as PARK7) is a redox-active protein that protects against oxidative stress. This study evaluated the hypothesis that DJ-1 sustains brainstem cardiovascular regulation via maintaining mitochondrial function in the rostral ventrolateral medulla (RVLM), a brainstem site known to maintain blood pressure and sympathetic vasomotor tone, during cardiovascular depression elicited by the organophosphate insecticide mevinphos. In Sprague-Dawley rats, intravenous administration of mevinphos (640 µg kg-1) resulted in progressive hypotension, accompanied by an increase (Phase I) followed by a decrease (Phase II) of an experimental index for spontaneous baroreflex-mediated sympathetic vasomotor tone, alongside elevation in mitochondrial superoxide levels in the RVLM. There was concurrent activation of DJ-1 induced by oxidative stress in the RVLM, which was causally and temporally related to translocation of DJ-1 to mitochondria, reduction in mitochondrial membrane potential, increase in cytosolic apoptosis-inducing factor level, and apoptotic cell death in this brainstem site. Loss-of-function by immunoneutralization of DJ-1 in the RVLM significantly exacerbated those biochemical and cellular events, enhanced the progressive hypotension, diminished the increased and augmented the decreased spontaneous baroreflex-mediated sympathetic vasomotor tone respectively during Phases I and II, and heightened lethality during mevinphos intoxication. We conclude that DJ-1 in the RVLM sustains brainstem cardiovascular regulation induced by mevinphos via maintaining mitochondrial function.

Primary School Teachers' Conceptions of Reading Comprehension Processes and Its Formulation.

Understanding reading comprehension processes is vital for teachers to effectively conduct teaching and assessment of reading in schools. Hong Kong students' outstanding reading performance internationally is commonly attributed to the implementation of reading comprehension models in its Chinese language curriculum, however, the understanding of teachers' conceptions of reading comprehension is still very limited. This phenomenographic study interviewed 28 in-service Chinese language teachers from eight Hong Kong primary schools and illustrated the elicited conceptions of a model of reading comprehension processes (i.e., Six Types of Reading Comprehension Process Model, a widely used model in Hong Kong). The three categories of teachers' conceptions found are as follows: understanding basic ideas of a text, sequential development of holistic comprehension skills, and fostering independent readers. This study further employed sense-making theory to investigate the formulation of the teachers' conceptions. It is found that the conceptions were shaped when teachers' conventional practices that focused on rote-learning interplayed with the continual regulating means of the implementation. Teachers are also highly influenced by factors like attainability by their students and agreement with own philosophy. This study also implied that teachers' beliefs will need to be brought to light in order for new learning to happen.

Senior General Surgery Resident Confidence in Performing Abdominal Wall Hernia Repairs.

BACKGROUND: It is expected that graduating general surgery residents be confident in performing common abdominal wall hernia repairs. The objective of our study was to assess the confidence of senior surgical residents in these procedures and to identify factors that correlate with confidence. METHODS: We performed a cross-sectional survey of PGY-4 and PGY-5 general surgery residents at ACGME-accredited programs in the United States in the spring of 2019. Respondents rated their confidence level in 12 hernia procedures on a Likert scale from 1 (not confident) to 5 (extremely confident). Respondents were classified as "Not Confident" (Not Confident, Minimally Confident, Neutral responses) or "Confident" (Confident, Extremely Confident responses). Resident characteristics, program characteristics, and operative experience were collected, and we calculated the area under the curve to screen which factors discriminated between those confident versus not. Multivariable Poisson regression was used to estimate prevalence ratios (PR) and 95% confidence intervals (CI) to identify which factors were most predictive. RESULTS: A total of 93 surveys were completed. Respondents reported low confidence rates (25%-60%) in the following hernia repairs: minimally invasive (MIS) inguinal, femoral, tissue (nonmesh) inguinal, pediatric inguinal, and abdominal wall reconstruction. High confidence rates (>80%) were reported for open umbilical, open ventral, and MIS ventral hernia repairs. For MIS inguinal hernia repair, PGY-5 level was associated with a twofold increase in confidence (PR = 2.01; 95% CI = 1.34-3.30), and dedicated research years were associated with low confidence (PR = 0.67; 95% CI = 0.43-1.04). In general, higher operative volumes of a specific repair were associated with increased confidence in that procedure. CONCLUSIONS: Senior surgical residents reported low confidence in performing a variety of essential hernia repairs (particularly MIS inguinal, femoral, and tissue inguinal). Addressing factors associated with low confidence may help increase resident confidence.

Frequency of Large Intrafractional Target Motions During Spine Stereotactic Body Radiation Therapy.

Spine stereotactic body radiation therapy frequently involves the delivery of high doses to targets in proximity to the spinal cord; thus, the radiation must be delivered with great spatial accuracy. Monitoring for large shifts in target and cord position that might occur during dose delivery is a challenge for clinics equipped with a conventional C-arm Linac. Treatment must be halted, then imaging and registration must be done to determine whether a significant shift has occurred. In this retrospective study of 1019 spine SBRT treatments, we investigated the number of target shifts >2 mm in any direction that occurred in carefully immobilized patients. Orthogonal kV images were acquired 3 to 5 times during each session using in an in-room imaging system. Although the likelihood of large intrafractional shifts was found to be very low, they did occur in 6 treatment sessions. Intrafractional monitoring was found to be an important safety component of treatment delivery.

Dose-Dependent Acute Circulatory Fates Elicited by Cadmium Are Mediated by Differential Engagements of Cardiovascular Regulatory Mechanisms in Brain.

Whereas cadmium is a toxicant that has been shown to cause cardiovascular toxicity and mortality in mammals, few mechanistic studies address its acute circulatory actions. The present study assessed the hypothesis that cadmium effects dose-dependent acute circulatory fates via differential participation of the cardiovascular regulatory mechanisms in brain. In Sprague-Dawley rats maintained under propofol anesthesia, cadmium acetate (8 mg/kg, iv) induced significantly high mortality rate within 10 min, concomitant with progressive decline toward zero level of mean arterial pressure (MAP), heart rate (HR), baroreflex-mediated sympathetic vasomotor tone, and carotid blood flow (CBF). There were concurrent tissue anoxia, cessation of microvascular perfusion, reduction of mitochondrial membrane potential and ATP production, and necrotic cell death in the rostral ventrolateral medulla (RVLM), the brain stem site that maintains blood pressure and sympathetic vasomotor tone. On the other hand, a lower-dose of cadmium (4 mg/kg, iv) resulted in only a transient decrease in MAP that was mirrored by an increase in CBF and baroreflex-mediated sympathetic vasomotor tone, minor changes in HR, along with transient hypoxia, and apoptotic cell death in RVLM. We conclude that cadmium elicits dose-dependent acute cardiovascular effects with differential underlying biochemical and neural mechanisms. At a higher-dose, cadmium induces high mortality by effecting acute cardiovascular collapse via anoxia, diminished tissue perfusion, mitochondrial dysfunction and bioenergetics failure that echo failure of cerebral autoregulation, leading to necrosis, and loss of functionality in RVLM. On the other hand, a lower-dose of cadmium elicits low mortality, transient decrease in arterial pressure, and hypoxia and apoptosis in RVLM that reflect sustained cerebral autoregulation.

Physiological and pathophysiological evaluation of baroreflex functionality with concurrent diffusion tensor imaging of its neural circuit in the rat.

BACKGROUND: By measuring the prevalence of neuronal traffic between two brain structures based on the notion that diffusion of water molecules along the axon in parallel bundles will create prominent anisotropy in the direction of the passage of action potentials, diffusion tensor imaging (DTI) may be taken as an effective tool for functional investigations. Demonstration of complementary results obtained from synchronized DTI of the baroreflex neural circuit and physiological or pathophysiological evaluation of baroreflex functionality should validate this notion. METHODS: We implemented concurrent changes in neuronal traffic within the neural circuit of the baroreflex-mediated sympathetic vasomotor tone in the brain stem and alterations of its experimental surrogate under physiological and pathophysiological conditions. We further evaluated the functional and clinical implications of results obtained from this experimental paradigm in conjunction with baroreflex induction and a mevinphos intoxication model of brain stem death. RESULTS: We found that robust connectivity existed between the nucleus tractus solitarii and rostral ventrolateral medulla, the afferent and efferent nuclei of the baroreflex-mediated sympathetic vasomotor. Intriguingly, this connectivity was either reversibly disrupted or irreversibly severed to reflect alterations in baroreflex responses to physiological or pathophysiological challenges. CONCLUSIONS: The capability to observe simultaneous and complementary changes in neuronal traffic within the neural circuit of the baroreflex-mediated sympathetic vasomotor tone and alterations of its experimental surrogate that bears technical, scientific and clinical implications sustains the notion that coupled with relevant physiological phenotypes, DTI can be an effective investigative tool for functional evaluations of brain stem activities.

PTEN/FLJ10540/PI3K/Akt cascade in experimental brain stem death: A newfound role for a classical tumorigenic signaling pathway.

Despite great advances in contemporary medicine, brain death still remains enigmatic and its cellular and molecular mechanisms unsettled. This review summarizes recent findings that substantiate the notion that PTEN/FLJ10540/PI3K/Akt cascade, the classical tumorigenic signaling pathway, is actively engaged in experimental brain stem death. These results were based on a clinically relevant animal model that employs the pesticide mevinphos as the experimental insult in Sprague-Dawley rats to mimic brain stem death in patients died of organophosphate poisoning. The neural substrate investigated is the rostral ventrolateral medulla (RVLM), a brain stem site classically known to maintain arterial pressure (AP) and is established to be the origin of a "life-and-death" signal detected from AP, which reflects brain stem cardiovascular dysregulation that precedes death. Activation of PI3K/Akt signaling pathway in the RVLM upregulates the nuclear factor-κB/nitric oxide synthase II/peroxynitrite cascade, resulting in impairment of brain stem cardiovascular regulation that leads to the loss of the "life-and-death" signal in experimental brain stem death. This process is reinforced by FLJ10540, a PI3K-association protein; and is counteracted by PTEN, a negative regulator of PI3K/Akt signaling. The concept that a classical signaling pathway in tumorigenesis is also an active player in cardiovascular dysregulation in brain stem death provides new ramifications for translational medicine. It promulgates the concept that rather than focusing on a particular disease condition, a new vista for future therapeutic strategy against both fatal eventualities should target at this common cellular cascade.

A case report of unexpected pathology within an incarcerated ventral hernia.

INTRODUCTION: Incidence of hernial appendicitis is 0.008%, most frequently within inguinal and femoral hernias. Up to 2.5% of appendectomy patients are found to have Crohn's disease. Elucidating the etiology of inflammation is essential for directing management. PRESENTATION OF CASE: A 51-year-old female with achondroplastic dwarfism, multiple cesarean sections, and subsequent massive incisional hernia, presented with ruptured appendicitis within her incarcerated hernia. She underwent diagnostic laparoscopy, appendectomy, intra-abdominal abscess drainage, and complete reduction of ventral hernia contents. She developed a nonhealing colocutaneous fistula, causing major disruptions to her daily life. She elected to undergo hernia repair with component separation for anticipated lack of domain secondary to her body habitus. Her operative course consisted of open abdominal exploration, adhesiolysis, colocutaneous fistula repair, ileocolic resection and anastomosis, and hernia repair with bioresorbable mesh. She tolerated the procedure well. Unexpectedly, ileocolic pathology demonstrated chronic active ileitis, diagnostic of Crohn's disease. DISCUSSION: Only two cases of hernial Crohn's appendicitis have been reported, both within Spigelian hernias. Appendiceal inflammation inside a hernia sac may be attributed to ischemia from extraluminal compression of the hernia neck. This case demonstrates a rare presentation of multiple concurrent surgical disease processes, each of which impact the patient's treatment plan. CONCLUSION: This is the first report of incisional hernia appendicitis with nonhealing colocutaneous fistulas secondary to Crohn's. It is a lesson in developing a differential diagnosis of an inflammatory process within an incarcerated hernia and management of the complications related to laparoscopic hernial appendectomy in a patient with undiagnosed Crohn's disease.

PTEN, a negative regulator of PI3K/Akt signaling, sustains brain stem cardiovascular regulation during mevinphos intoxication.

Activation of PI3K/Akt signaling, leading to upregulation of nitric oxide synthase II (NOS II)/peroxynitrite cascade in the rostral ventrolateral medulla (RVLM), the brain stem site that maintains blood pressure and sympathetic vasomotor tone, underpins cardiovascular depression induced by the organophosphate pesticide mevinphos. By exhibiting dual-specificity protein- and lipid-phosphatase activity, phosphatase and tensin homolog (PTEN) directly antagonizes the PI3K/Akt signaling by dephosphorylation of phosphatidylinositol-3,4,5-trisphosphate, the lipid product of PI3K. Based on the guiding hypothesis that PTEN may sustain brain stem cardiovascular regulation during mevinphos intoxication as a negative regulator of PI3K/Akt signaling in the RVLM, we aimed in this study to clarify the mechanistic role of PTEN in mevinphos-induced circulatory depression. Microinjection bilaterally of mevinphos (10 nmol) into the RVLM of anesthetized Sprague-Dawley rats induced a progressive hypotension and a decrease in baroreflex-mediated sympathetic vasomotor tone. There was progressive augmentation in PTEN activity as reflected by a decrease in the oxidized form of PTEN in the RVLM during mevinhpos intoxication, without significant changes in the mRNA or protein level of PTEN. Loss-of-function manipulations of PTEN in the RVLM by immunoneutralization, pharmacological blockade or siRNA pretreatment significantly potentiated the increase in Akt activity or NOS II/peroxynitrite cascade in the RVLM, enhanced the elicited hypotension and exacerbated the already reduced baroreflex-mediated sympathetic vasomotor tone. We conclude that augmented PTEN activity via a decrease of its oxidized form in the RVLM sustains brain stem cardiovascular regulation during mevinphos intoxication via downregulation of the NOS II/peroxynitrite cascade as a negative regulator of PI3K/Akt signaling.

Surgeons' Experiences With Patients' Concerns Regarding Trainees.

OBJECTIVE: Little is known about surgeons' attitudes toward patients' concerns about the role of trainees in their care. The nature of the discussion between surgeons and their patients about trainees and the effect on how patients are cared for is an important part of patient-centered care. We aim to elucidate surgeons' attitude toward patients' concerns regarding trainee involvement in their care. DESIGN: An electronic, web-based 15-question survey (SurveyMonkey) was used. SETTING: Surveys were sent to 528 e-mail accounts of the members of the Massachusetts Chapter of the American College of Surgeons. Surgeon demographics, the frequency and nature of patients' concerns about trainees, and the reactions to these concerns by surgeons were explored. PARTICIPANTS: Of the 528 surgeons surveyed, 109 completed the online survey. Most specialties of surgery were represented. RESULTS: We analyzed 109 responses (21% response rate). Most surgeons from a variety of specialties were involved with teaching medical students and residents. Half the respondents trained fellows as well. Patients' concerns are raised more often in the community setting where surgeons are more likely to alter their practice. CONCLUSIONS: Although patients' concerns about trainee involvement are infrequent, they arise enough to deserve specific attention in the current patient-centric environment. Surgeons successfully negotiate to have trainee involvement in the vast majority of cases. Specific guidelines should be developed and adopted to ensure that patients consent to trainee involvement and understand the role of trainees and their supervision.

Transition from oxidative stress to nitrosative stress in rostral ventrolateral medulla underlies fatal intoxication induced by organophosphate mevinphos.

As the most widely used pesticides in the world, fatal incidence of suicidal poisoning by organophosphate compounds is high and is often associated with cardiovascular toxicity. Using the pesticide mevinphos as our tool, we investigated the roles of oxidative stress and nitrosative stress at the rostral ventrolateral medulla (RVLM), the brain stem site that maintains arterial pressure (AP) and sympathetic vasomotor tone, in the cardiovascular depressive effects of organophosphate poisons. Microinjection of mevinphos (10 nmol) into the RVLM of anesthetized Sprague-Dawley rats induced progressive hypotension that was accompanied by an increase (phase I), followed by a decrease (phase II) of an experimental index of baroreflex-mediated sympathetic vasomotor tone, with a fatality rate of 35%. During phase I, there was a preferential upregulation of angiotensin type I receptor (AT1R) messenger RNA (mRNA) and protein that leads to activation of NADPH oxidase (Nox) and increase in superoxide at the RVLM. Pharmacological antagonism of these signals exacerbated fatality and shorted survival time by eliminating baroreflex-mediated sympathetic vasomotor tone, AP, and heart rate. During phase II, there was a progressive upregulation of angiotensin type II receptor (AT2R) mRNA and protein that leads to increase in peroxynitrite in the RVLM, blockade of both sustained brain stem cardiovascular regulation and improved survival. We further found that AT1R and AT2R cross-interacted at transcriptional and signaling levels in the RVLM. We conclude that a transition from AT1R-mediated oxidative stress to AT2R-mediated nitrosative stress in the RVLM underlies the shift from sustained to impaired brain stem cardiovascular regulation that underpins cardiovascular fatality during mevinphos intoxication.

Ideal timing of surgery for acute uncomplicated appendicitis.

BACKGROUND: Early surgery for appendicitis is thought to avoid complications associated with appendiceal rupture. AIMS: This study was to evaluate the effect of timing of surgery on complications, length of stay (LOS) and cost in patients undergoing appendectomy. MATERIALS AND METHODS: Retrospective review of 396 patients with appendectomies from January 1, 2005 to December 31, 2007 was performed. Demographic data, time of presentation, physical findings, diagnostic data, operating room times, LOS, cost and complications were collected. Patients were divided into 4 groups based on time from presentation to appendectomy. RESULTS: Pathology confirmed appendicitis in 354 (89%) patients. Most patients (90%) had surgery within 18 h of presentation. Timing of surgery did not affect the incidence of purulent peritonitis (P = 0.883), abscess (P = 0.841) or perforation (P = 0.464). LOS was significantly shorter for patients with emergency department registration to operating room times less than 18 h (P < 0.0001). Costs were significantly higher for patients with times to operating room greater than 18 h (P < 0.001). CONCLUSION: Timing of surgery did not affect the incidence of complications or perforated appendicitis. However, delay in surgical consultation and surgery are associated with increased LOS and increased hospital costs. The optimal timing of appendectomy for uncomplicated acute appendicitis appears to be within 18 h of emergency department presentation.