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George A Mashour

Publications and source records attributed to George A Mashour.

14 recordsLinked to original sources
PubMed2006

Integrating the science of consciousness and anesthesia.

The nature and mechanism of human consciousness is emerging as one of the most important scientific and philosophical questions of the 21st century. Disregarded as a subject of serious inquiry throughout most of the 20th century, it has now regained legitimacy as a scientific endeavor. The investigation of consciousness and the mechanisms of general anesthesia have begun to converge. In the present article I provide an introduction to the study of consciousness, describe the neural correlates of consciousness that may be targets of general anesthetics, and suggest an integrated approach to the science of consciousness and anesthesia.

Anesthesia, General↗
PubMed2006

Craniocervical extension improves the specificity and predictive value of the Mallampati airway evaluation.

BACKGROUND: The modified Mallampati (MMP) classification is a standard airway examination that assesses mouth opening and structures within the oral cavity. Recent data suggest that maximal mouth opening (as measured by interdental distance) is possible only with extension of the craniocervical junction. Because the MMP examination is performed with the head in a neutral position, the airway may appear worse because of submaximal interdental distance. We hypothesized that adding craniocervical extension to the MMP would allow for greater mouth opening, lower scores, and less false positives than the traditional MMP examination. METHODS: Multiple clinicians with at least 1 yr of airway experience evaluated adult airways (n = 60) with the MMP examination (with head in neutral position). The same examination was then repeated with the addition of craniocervical extension (Extended Mallampati Score, EMS). RESULTS: On average, craniocervical extension decreased the MMP class (P < 0.002). The EMS improved specificity from 70% to 80% and positive predictive value from 24% to 31% when compared with the traditional MMP. The sensitivity (83%) was the same for MMP and EMS. CONCLUSIONS: Craniocervical extension improves the specificity and positive predictive value of the MMP airway evaluation while retaining sensitivity of the traditional MMP examination. The introduction of the EMS into clinical practice should be considered.

Adult↗
PubMed2005

Differential modulation of malignant peripheral nerve sheath tumor growth by omega-3 and omega-6 fatty acids.

Neurofibromatosis type 1 (NF1) is a common genetic disorder of the nervous system resulting in neurofibromas and malignant peripheral nerve sheath tumors (MPNST). In this study, we report the modulation of murine and human MPNST cell growth by the fatty acids docosahexaenoic acid (DHA) and arachidonic acid (AA). DHA demonstrated a tendency to stimulate cell growth at low doses and induce apoptosis at high doses, paralleled by the activation of ERK and caspase-3. Furthermore, high-dose DHA reversed the stimulation of MPNST cell growth by a number of growth factors suggested to have a pathogenic effect in NF1 and inhibited MPNST growth in vivo. AA was found to have a reciprocal activity in vitro, stimulating MPNST cell growth at comparable concentrations and reducing DHA activation of ERK. These findings introduce fatty acids as a possible regulator of MPNST development in NF1 patients.

Animals↗
PubMed2005

Mechanisms of general anesthesia: from molecules to mind.

Despite the widespread presence of clinical anesthesiology in medical practice, the mechanism by which diverse inhalational agents result in the state of general anesthesia remains unknown. Over recent decades, our understanding of general anesthetic mechanisms has evolved dramatically from early unitary hypotheses, largely due to the development and influence of a myriad of scientific disciplines ranging from molecular biology to cognitive neuroscience. These discoveries have led to a renaissance of investigation into the mechanisms of general anesthetics and have generated both novel answers and questions. In this chapter, we review the major hypotheses of general anesthetic mechanisms of action and present an expanded overview of current investigation into those mechanisms. We also present a framework to aid in thinking about the actions of these agents, highlighting the relationship between putative targets at the molecular level and the more integrated functional changes in behavior and consciousness.

Anesthesia, General↗
PubMed2005

Psychosurgery: past, present, and future.

Psychosurgery, the neurosurgical treatment of psychiatric disease, has a history dating back to antiquity, and involves all of the clinical neurosciences. This review discusses the history of psychosurgery, its development in the 19th century, and the conditions of its use and abuse in the 20th century, with a particular focus on the frontal lobotomy. The transition to the modern era of psychosurgery is discussed, as well as the neurobiology underlying current psychosurgical procedures. The techniques of stereotactic cingulotomy, capsulotomy, subcaudate tractotomy, and limbic leukotomy are described, as well their indications and side effects. Due to the past abuse of psychosurgery, procedures are currently under strict control, and the example of the Cingulotomy Committee at the Massachusetts General Hospital is discussed. Finally, future directions of psychosurgery and somatic therapies are explored, including transcranial magnetic stimulation, vagal nerve stimulation, deep brain stimulation, gene therapy, and stem cell therapy. In summary, this review provides a concise yet comprehensive introduction to the history, current practice, and future trends of neurosurgery for psychiatric disorders.

Brain↗
PubMed2005

Spinal anesthesia and Ogilvie's syndrome.

Ogilvie's syndrome is an uncommon disorder of acute colonic pseudoobstruction that is often associated with concomitant medical disease or psychiatric medication. Therapeutic interventions include cholinesterase inhibitors, colonic decompression, and, in severe cases, surgery. We report a case of functional obstruction that was resolved after spinal anesthesia. The effect of spinal anesthesia on the autonomic control of colonic motility is discussed, and the literature on neuraxial blockade and Ogilvie's syndrome is reviewed.

Aged↗
PubMed2005

Anesthetic management of Turner syndrome: a systematic approach.

Turner syndrome is a complex and common genetic disorder that affects women and is associated with a wide variety of anatomic and physiological disorders. These abnormalities, especially those relating to the airway and cardiovascular system, pose a challenge to the anesthesiologist. We report a case of Turner syndrome associated with mental retardation and difficult airway, followed by a discussion of the perioperative management and review of the relevant literature. We also provide a concise tabular summary of the many problems associated with Turner syndrome and give guidelines for a systematic perioperative approach.

Anesthesia↗
PubMed2004

Circulating growth factor levels are associated with tumorigenesis in neurofibromatosis type 1.

PURPOSE: Neurofibromatosis type 1 (NF1) is characterized by systemic development of neurofibromas. Early clinical diagnosis can be ambiguous, and genetic diagnosis can be prohibitively difficult. Dysregulation of a number of growth factors has been suggested to be a mechanism of pathogenesis. This study was performed to assess the contribution of circulating growth factors for diffuse tumorigenesis and the diagnostic value of circulating growth factor identification in serum. EXPERIMENTAL DESIGN: The growth stimulation of neurofibroma-derived cells by serum from NF1 patients was tested, and serum growth factor levels in a cohort of NF1 patients (n = 39) between the ages of 7 and 70 years were analyzed. RESULTS: Concentrations of midkine (MK) and stem cell factor, but not epidermal growth factor, were substantially increased in serum of NF1 patients when compared with healthy controls. Within the NF1 group, MK levels increased dramatically at puberty from an average of 0.79 ng/mL in patients <18 years to 1.18 ng/mL in patients >18 years old. Stem cell factor and MK concentrations above a defined threshold in serum of NF1 patients are of diagnostic benefit for 96% of patients in the cohort tested. Furthermore, serum from NF1 patients enhanced proliferation of human neurofibroma-derived primary Schwann cells and endothelial cells substantially better than normal serum. CONCLUSIONS: Enhanced circulating growth factor levels contribute to diffuse tumorigenesis in NF1 and may provide the basis for molecular diagnosis.

Adolescent↗