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Daou BJ, Palmateer G, Wilkinson DA, Thompson BG, Maher CO, Chaudhary N, Gemmete JJ, Hayman JA, Lam K, Wahl DR, Kim M, Pandey AS. Radiation-Induced Imaging Changes and Cerebral Edema following Stereotactic Radiosurgery for Brain AVMs. AJNR Am J Neuroradiol 2020; 42:82-87. [PMID: 33214183 DOI: 10.3174/ajnr.a6880] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 08/17/2020] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE T2 signal and FLAIR changes in patients undergoing stereotactic radiosurgery for brain AVMs may occur posttreatment and could result in adverse radiation effects. We aimed to evaluate outcomes in patients with these imaging changes, the frequency and degree of this response, and factors associated with it. MATERIALS AND METHODS Through this retrospective cohort study, consecutive patients treated with stereotactic radiosurgery for brain AVMs who had at least 1 year of follow-up MR imaging were identified. Logistic regression analysis was used to evaluate predictors of outcomes. RESULTS One-hundred-sixty AVMs were treated in 148 patients (mean, 35.6 years of age), including 42 (26.2%) pediatric AVMs. The mean MR imaging follow-up was 56.5 months. The median Spetzler-Martin grade was III. The mean maximal AVM diameter was 2.8 cm, and the mean AVM target volume was 7.4 mL. The median radiation dose was 16.5 Gy. New T2 signal and FLAIR hyperintensity were noted in 40% of AVMs. T2 FLAIR volumes at 3, 6, 12, 18, and 24 months were, respectively, 4.04, 55.47, 56.42, 48.06, and 29.38 mL Radiation-induced neurologic symptoms were encountered in 34.4%. In patients with radiation-induced imaging changes, 69.2% had new neurologic symptoms versus 9.5% of patients with no imaging changes (P = .0001). Imaging changes were significantly associated with new neurologic findings (P < .001). Larger AVM maximal diameter (P = .04) and the presence of multiple feeding arteries (P = .01) were associated with radiation-induced imaging changes. CONCLUSIONS Radiation-induced imaging changes are common following linear particle accelerator-based stereotactic radiosurgery for brain AVMs, appear to peak at 12 months, and are significantly associated with new neurologic findings.
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Affiliation(s)
- B J Daou
- Neurosurgery (B.J.D., G.P., D.A.W., B.G.T., C.O.M., N.C., J.J.G., A.S.P.)
| | - G Palmateer
- Neurosurgery (B.J.D., G.P., D.A.W., B.G.T., C.O.M., N.C., J.J.G., A.S.P.)
| | - D A Wilkinson
- Neurosurgery (B.J.D., G.P., D.A.W., B.G.T., C.O.M., N.C., J.J.G., A.S.P.)
| | - B G Thompson
- Neurosurgery (B.J.D., G.P., D.A.W., B.G.T., C.O.M., N.C., J.J.G., A.S.P.)
| | - C O Maher
- Neurosurgery (B.J.D., G.P., D.A.W., B.G.T., C.O.M., N.C., J.J.G., A.S.P.)
| | - N Chaudhary
- Neurosurgery (B.J.D., G.P., D.A.W., B.G.T., C.O.M., N.C., J.J.G., A.S.P.).,Radiology (N.C., J.J.G.)
| | - J J Gemmete
- Neurosurgery (B.J.D., G.P., D.A.W., B.G.T., C.O.M., N.C., J.J.G., A.S.P.).,Radiology (N.C., J.J.G.)
| | - J A Hayman
- From the Departments of Radiation Oncology (J.A.H., K.L., D.R.W., M.K.).,Radiation Oncology (J.A.H., K.L., D.R.W., M.K.), University of Michigan, Ann Arbor, Michigan
| | - K Lam
- From the Departments of Radiation Oncology (J.A.H., K.L., D.R.W., M.K.).,Radiation Oncology (J.A.H., K.L., D.R.W., M.K.), University of Michigan, Ann Arbor, Michigan
| | - D R Wahl
- From the Departments of Radiation Oncology (J.A.H., K.L., D.R.W., M.K.).,Radiation Oncology (J.A.H., K.L., D.R.W., M.K.), University of Michigan, Ann Arbor, Michigan
| | - M Kim
- From the Departments of Radiation Oncology (J.A.H., K.L., D.R.W., M.K.).,Radiation Oncology (J.A.H., K.L., D.R.W., M.K.), University of Michigan, Ann Arbor, Michigan
| | - A S Pandey
- Neurosurgery (B.J.D., G.P., D.A.W., B.G.T., C.O.M., N.C., J.J.G., A.S.P.)
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Yegneswaran PK, Gray MR, Thompson BG. Experimental simulation of dissolved oxygen fluctuations in large fermentors: effect on Streptomyces clavuligerus. Biotechnol Bioeng 2012; 38:1203-9. [PMID: 18600716 DOI: 10.1002/bit.260381012] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
An experimental Monte Carlo method was used to study the effect of fluctuations in oxygen concentration on the synthesis of antibiotics by Streptomyces clavuligerus. Air was supplied to the culture in a 2-L fermentor in random cycles following the lognormal distribution in order to model the circulation within large production-scale vessels. Each cycle consisted of air supply for 5 s followed by no aeration for the balance of the cycle time which ranged from 8 to 44 s, with a mean time of 20 s. Comparable experiments were also conducted with constant period cycling of air and with continuous supply of air. The yields of cephamycin C and its precursor, penicillin N, were suppressed by the Monte Carlo simulation of circulation in a large tank, as compared to constant period cycling. The concentration of dissolved oxygen remained at a low, ca. 5% of saturation, for 5-10 h longer during the Monte Carlo experiment than during the periodic aeration experiment. The biosynthetic enzymes, which are sensitive to oxygen levels, were likely affected not only by the mean time of cycling but also by the distribution of the cycles.
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Affiliation(s)
- P K Yegneswaran
- Department of Chemical Engineering, University of Alberta, Edmonton, Canada T6G 2G6
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Abstract
A control system has been devised for the maintenance of stable ammonium concentrations throughout a fedbatch fermentation. The control system is based on an ammonia gas-sensing electrode that monitors a pH-adjusted effluent stream from the fermentor. To overcome the time lag between the fermentor and the electrode, feedback control included metered flows of ammonium to both the fermentor and the electrode vessel. The system was used to study the growth of Escherichia coli B (ATCC 11303) at controlled ammonium concentrations of 5 to 200mM. Apparent specific growth rates, biomass and protein production, and glucose yields were essentially constant from 5 to 170mM. Above 170mM ammonium growth was inhibited. As ammonium concentration decreased from 170 to 5mM, ammonium yields increased from 1 to 24 g cell dry wt/g ammonium utilized. The results demonstrate that control of ammonium concentrations at levels so low that ammonium would be exhausted in batch fermentations can significantly increase overall ammonium yields.
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Affiliation(s)
- B G Thompson
- Biotechnology Department, Alberta Research Council, 11315 87th Avenue, Edmonton, Alberta, T6G 2C2 Canada
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Abstract
Murine hybridoma cells were grown in a bubble column that was inclined up to 45 degrees from vertical. Inclining the column by a few degrees separated the rising bubbles against the upper surface, leaving the bulk of the liquid bubble free. The liquid was circulated well by the rising bubbles, but collection of cells by rising bubbles and exposure of cells to bursting bubbles were minimized. Maximum viable cell count and exponential growth of the cells were not affected by inclination, but an inclination of 30 degrees gave an antibody titer of 42 mg/L, which more than doubled the yield of 17 mg/L in the vertical position. By comparison, the culture gave yields of 30 mg/L when grown in spinner flasks. The enhanced antibody production in the inclined bioreactor corresponded to a prolonged stationary phase of 45 h. (c) 1995 John Wiley & Sons, Inc.
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Affiliation(s)
- G Z Lu
- Department of Chemical Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2G6
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Abstract
Escherichia coli DH5alpha, carrying the pUC19 plasmid for the lacZ fragment of beta-galactosidase and ampicillin resistance, was grown in a batch fermentor under conditions of fluctuating oxygen supply. A Monte Carlo method was used to control the on/off supply of air to simulate circulation of cells in a large fermentor. Rapid changes in oxygen supply reduced the rates of oxygen uptake the carbon dioxide release and prolonged the active second growth phase in batch culture, compared to growth with continuous aeration. Amplification of the plasmid was observed during the stationary phase when air supplied continuously, but not during the Monte Carlo experiments.
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Affiliation(s)
- P K Namdev
- Department of Chemical Engineering, University of Alberta, Edmonton, Alberta, Canada
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Gandhi D, Pandey A, Ansari SA, Gemmete JJ, Thompson BG, Mukherji SK. Multi-detector row CT angiography with direct intra-arterial contrast injection for the evaluation of neurovascular disease: technique, applications, and initial experience. AJNR Am J Neuroradiol 2009; 30:1054-8. [PMID: 19213819 DOI: 10.3174/ajnr.a1438] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The purpose of this study was to evaluate the usefulness of 64-section multi-detector row CT angiography (CTA) with direct intra-arterial contrast injection (IA-CTA) for the evaluation of neurovascular disease. This technique was used in 11 patients at our institution. All studies were technically successful, and there were no complications. Small vascular malformations were mapped easily on high-resolution IA-CTA images, enabling microsurgical resection or stereotactic radiosurgery. In a similar fashion, additional morphologic features were revealed on IA-CTA images not seen on standard 2D and 3D digital subtraction angiography. Of 11 patients undergoing IA-CTA, 7 patients had further anatomic clarity of the small arteriovenous fistula/malformation and 4 patients had changes in the treatment plan on the basis of the IA-CTA findings.
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Affiliation(s)
- D Gandhi
- Division of Interventional Neuroradiology, Russell H. Morgan Department of Radiology, Johns Hopkins Medical Institutions, Baltimore, MD 21287, USA.
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Ansari SA, Lassig JP, Nicol E, Thompson BG, Gemmete JJ, Gandhi D. Transarterial embolization of a cervical dural arteriovenous fistula. Presenting with subarachnoid hemorrhage. Interv Neuroradiol 2006; 12:313-8. [PMID: 20569588 DOI: 10.1177/159101990601200404] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Accepted: 11/15/2006] [Indexed: 11/17/2022] Open
Abstract
SUMMARY We describe a case of a 75-year-old man who presented with acute onset of headache and subarachnoid hemorrhage and initial cerebral angiography was deemed "negative". In retrospect, a faint contrast collection was present adjacent to the right vertebral artery at the C1 level suspicious for a small dural arteriovenous fistula (dAVF). Follow-up angiography with selective microcatheter injections of the right vertebral artery and C1 radicular artery confirmed a complex dAVF with characteristically specific venous drainage patterns associated with a subarachnoid hemorrhage presentation. Subsequently, the cervical dAVF was treated with superselective glue embolization resulting in complete occlusion. Cervical dAVFs are extremely rare vascular causes of subarachnoid hemorrhage. Both diagnostic angiography and endovascular treatment of these lesions can be challenging, especially in an emergent setting, requiring selective evaluation of bilateral vertebral arteries and careful attention to their cervical segments. Although only a single prior case of a cervical dAVF presenting with subarachnoid hemorrhage has been successfully treated with embolization, modern selective transarterial techniques may allow easier detection and treatment of subtle pathologic arteriovenous connections.
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Affiliation(s)
- S A Ansari
- Department of Radiology, University of Michigan Health System, Ann Arbor, MI, U.S.A. -
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Affiliation(s)
- R M Pluta
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland, USA
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Abstract
OBJECTIVE To determine the efficacy of topical dexamethasone in reducing nerve dysfunction after axonotmesis injury. STUDY DESIGN A three-armed, blinded study including sham, control, and test groups was designed using the rat sciatic nerve crush injury model. METHODS Twenty-two rats were randomly assigned to a control group or a topical steroid group. A standardized sciatic nerve crush injury was performed under sterile conditions on each animal. A separate group of five rats underwent a sham operation to isolate the crush injury as the source of postoperative dysfunction in the control and steroid groups. All animals underwent walking track analysis with calculation of the sciatic functional index (SFI) before surgery and through the postoperative recovery period. Dexamethasone saturated Gelfoam was placed at the site of injury in the topical steroid group. The functional performance of each group was compared throughout the recovery period. RESULTS No morbidity associated with topical application of steroids at the injury site was noted. The topical steroid group had improved recovery at postoperative days 14, 18, and 22. This difference was statistically significant at day 14. At the termination of the study, there was a clear trend toward superior recovery for the steroid group compared with controls (90% vs. 73%), but this difference did not reach statistical significance. CONCLUSIONS Clinical use of topical steroids to reduce postoperative nerve dysfunction warrants further study.
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Affiliation(s)
- E B Galloway
- Division of Otolaryngology, University of Utah, Salt Lake City, USA
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Abstract
Telemedicine technology enabled this class to meet. The Chapel Hill instructor could not have traveled to Scotland Neck for the classes, and the class members could not have taken time away from their jobs to travel to Chapel Hill. The technology allowed the participants to fit the classes into their schedules. For the group of managers at this small, isolated hospital, the experience of participating in a management class with an expert was a positive one. They were introduced to standard management practices, learned new skills, and formed a support group/team onsite. The students felt close to the leader, yet the physical distance made her an outsider in a way that encouraged frankness. The technology seemed to foster the best of both worlds--intimacy, yet physical distance and, thus, safety. These new managers were able to take part in a course that taught tangible skills for improving their job performance and, more important, afforded access to resources outside of Halifax County. They were able to step away from their daily routine and interact with outsiders and each other in new ways, without the stress and expense of travel. The results of this pilot study indicate that distance learning is feasible for courses of this kind. Staff burnout and turnover are chronic problems in rural facilities, with isolation contributing to job dissatisfaction. Distance learning offers exciting possibilities for addressing these problems in healthcare settings across the country.
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Affiliation(s)
- L Whitener
- Cecil G. Sheps Center for Health Services Research, University of North Carolina at Chapel Hill, USA
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Harrigan MR, Satti JA, Deveikis JP, Thompson BG. Effect of hematocrit on calculation of cerebral blood flow and lambda in xenon CT. Keio J Med 2000; 49 Suppl 1:A36-7. [PMID: 10750333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Knowledge of the patient's hematocrit is necessary for calculation of cerebral blood flow (CBF) with xenon CT, and is a potential source of error. This study quantifies the effect of hematocrit on the calculation of CBF and lambda, and determines if the magnitude of the effect is dependent on actual CBF or lambda. The effect of hematocrit was measured empirically using software employing the numerical calculation method. CBF and lambda were found to be inversely related to hematocrit. The percent error produced by an inaccurate hematocrit is greater for lower actual CBF values.
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Pluta RM, Afshar JK, Thompson BG, Boock RJ, Harvey-White J, Oldfield EH. Increased cerebral blood flow but no reversal or prevention of vasospasm in response to L-arginine infusion after subarachnoid hemorrhage. J Neurosurg 2000; 92:121-6. [PMID: 10616090 DOI: 10.3171/jns.2000.92.1.0121] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT The reduction in the level of nitric oxide (NO) is a purported mechanism of delayed vasospasm after subarachnoid hemorrhage (SAH). Evidence in support of a causative role for NO includes the disappearance of nitric oxide synthase (NOS) from the adventitia of vessels in spasm, the destruction of NO by hemoglobin released from the clot into the subarachnoid space, and reversal of vasospasm by intracarotid NO. The authors sought to establish whether administration of L-arginine, the substrate of the NO-producing enzyme NOS, would reverse and/or prevent vasospasm in a primate model of SAH. METHODS The study was composed of two sets of experiments: one in which L-arginine was infused over a brief period into the carotid artery of monkeys with vasospasm, and the other in which L-arginine was intravenously infused into monkeys over a longer period of time starting at onset of SAH. In the short-term infusion experiment, the effect of a 3-minute intracarotid infusion of L-arginine (intracarotid concentration 10(-6) M) on the degree of vasospasm of the right middle cerebral artery (MCA) and on regional cerebral blood flow (rCBF) was examined in five cynomolgus monkeys. In the long-term infusion experiment, the effect of a 14-day intravenous infusion of saline (control group, five animals) or L-arginine (10(-3) M; six animals) on the occurrence and degree of cerebral vasospasm was examined in monkeys. The degree of vasospasm in all experiments was assessed by cerebral arteriography, which was performed preoperatively and on postoperative Days 7 (short and long-term infusion experiments) and 14 (long-term infusion experiment). In the long-term infusion experiment, plasma levels of L-arginine were measured at these times in the monkeys to confirm L-arginine availability. Vasospasm was not affected by the intracarotid infusion of L-arginine (shown by the reduction in the right MCA area on an anteroposterior arteriogram compared with preoperative values). However, intracarotid L-arginine infusion increased rCBF by 21% (p < 0.015; PCO2 38-42 mm Hg) in all vasospastic monkeys compared with rCBF measured during the saline infusions. In the long-term infusion experiment, vasospasm of the right MCA occurred with similar intensity with or without continuous intravenous administration of L-arginine on Day 7 and had resolved by Day 14. The mean plasma L-arginine level increased during infusion from 12.7+/-4 microg/ml on Day 0 to 21.9+/-13.1 microg/ml on Day 7 and was 18.5+/-3.1 microg/ml on Day 14 (p < 0.05). CONCLUSIONS Brief intracarotid and continuous intravenous infusion of L-arginine did not influence the incidence or degree of cerebral vasospasm. After SAH, intracarotid infusion of L-arginine markedly increased rCBF in a primate model of SAH. These findings discourage the use of L-arginine as a treatment for vasospasm after SAH.
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Affiliation(s)
- R M Pluta
- Surgical Neurology Branch and Clinical Neuroscience Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA.
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Thompson BG. The role of performance assessment in the regulation of underground disposal of radioactive wastes: an international perspective. Risk Anal 1999; 19:809-846. [PMID: 10765435 DOI: 10.1023/a:1007010409328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Much has been written about the development and application of quantitative methods for estimating under uncertainty the long-term radiological performance of underground disposal of radioactive wastes. Until recently, interest has been focused almost entirely on the technical challenges regardless of the role of the organization responsible for these analyses. Now the dialogue between regulators, the repository developer or operator, and other interested parties in the decision-making process receives increasing attention, especially in view of some current difficulties in obtaining approvals to construct or operate deep facilities for intermediate or high-level wastes. Consequently, it is timely to consider the options for regulators' review and evaluation of safety submissions, at the various stages in the site selection to repository closure process, and to consider, especially, the role for performance assessment (PA) within the programs of a regulator both before and after delivery of such a submission. The origins and broad character of present regulations in the European Union (EU) and in the OECD countries are outlined and some regulatory PA reviewed. The issues raised are discussed, especially in regard to the interpretation of regulations, the dangers from the desire for simplicity in argument, the use of regulatory PA to review and challenge the PA in the safety case, and the effects of the relationship between proponent and regulator. Finally, a very limited analysis of the role of PA in public hearings is outlined and recommendations are made, together with proposals for improving the mechanisms for international collaboration on technical issues of regulatory concern.
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Ross DA, Marentette LJ, Thompson BG, Haller JS. Use of hydroxyapatite bone cement to prevent cerebrospinal fluid leakage through the frontal sinus: technical report. Neurosurgery 1999; 45:401-2; discussion 402-3. [PMID: 10449089 DOI: 10.1097/00006123-199908000-00045] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
OBJECTIVE To test the efficacy of a simple technique of frontal sinus obliteration during low frontal craniotomy using hydroxyapatite cement instead of more traditional methods, such as pericranial flaps, free muscle or adipose grafts, lumbar drainage, or fibrin glue. METHODS Eight patients undergoing low frontal craniotomy for intradural surgery had the frontal sinus obliterated by careful removal of mucosa followed by filling of the sinus with hydroxyapatite bone cement. No other adjuncts for preventing cerebrospinal fluid leakage through the sinus were used. RESULTS At an average follow-up of 9 months, there were no cerebrospinal fluid leaks, infections, instances of resorption, or cosmetic deformities. CONCLUSION Hydroxyapatite bone cement seems to be a simple and effective method for frontal sinus obliteration and prevention of cerebrospinal fluid leakage.
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Affiliation(s)
- D A Ross
- Department of Surgery, University of Michigan Medical Center, Ann Arbor, USA
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Jacobs JM, Shelton C, Thompson BG. Combined transarterial and transvenous embolisation of jugulotympanic paragangliomas. Interv Neuroradiol 1998; 4:223-30. [PMID: 20673414 DOI: 10.1177/159101999800400306] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/1998] [Accepted: 06/20/1998] [Indexed: 11/17/2022] Open
Abstract
SUMMARY Paragangliomas of the jugular region present a greater challenge to the surgeon than paragangliomas in other locations. Because of the vascular nature of the tumour, bleeding can be substantial not only from arterial inflow to the tumour, but also from venous bleeding, if not embolised prior to surgery. Six patients were treated with combined transarterial and transvenous embolisation followed by surgical resection. In each instance, the diagnosis of jugulotympanic paraganglioma was suspected based on MR features. Substantial reduction in loss of blood appears to result from the combined transarterial and transvenous embolisation approach.
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Affiliation(s)
- J M Jacobs
- Department of Radiology, University of Utah Medical School; Salt Lake City, Utah, USA
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Abstract
The morbidity and mortality associated with third ventriculostomy has decreased significantly over the past 75 years since its introduction by Walter Dandy. Now more commonly performed using an endoscopic method, the significant morbidity of third ventriculostomy has dropped to approximately 5%; essentially that associated with ventriculoscopy in general. However, the possible complication of massive subarachnoid hemorrhage resulting from perforation of the basilar artery or its branches in the course of fenestration of the floor of the third ventricle has only recently been reported. In our case, subsequent to a vascular injury, a pseudoaneurysm developed at the site of vascular perforation, which was then appropriately controlled. The patient has since made a full recovery. Our goal is to remind the endoscopist of this unusual complication and to discuss our management strategies.
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Affiliation(s)
- K Abtin
- Department of Neurological Surgery, University of Utah, Primary Children's Medical Center, Salt Lake City 84113, USA
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Abstract
When exposing the horizontal petrous carotid artery in preparation for intrapetrous carotid bypass, the surgeon has no definite landmarks to localize the perimeter of the cochlea. The results of this study provide a practical, consistent, and safe method to maximize carotid artery exposure while minimizing cochlear injury. We measured the carotid-cochlea distance (mean, 4.3 mm) and the carotid-cochlear angle (mean, 10.8 degrees) in 33 temporal bones in which the extended middle fossa approach had been performed. We correlated this distance to the width of a Sheehy weapon knife, which can be easily measured intraoperatively. Twenty-five temporal bones were imaged prior to surgical exposure using a new computed tomography (CT) protocol that can be used for preoperative assessment of the carotid-cochlear anatomy. The carotid-cochlea distance and carotid-cochlear angle measured on CT are compared with postsurgical measurements.
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Affiliation(s)
- L A Dew
- Division of Otolaryngology, University of Utah, Salt Lake City, USA
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Affiliation(s)
- M E Williams
- Program on Aging, School of Medicine, University of North Carolina, Chapel Hill 27599-7550, USA
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Williams ME, Thompson BG. Geriatric health care in the 21st century. N C Med J 1996; 57:368-71. [PMID: 8937162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- M E Williams
- Program on Aging, School of Medicine, University of North Carolina, Chapel Hill 27599, USA
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Abstract
To determine the distribution of nitric oxide synthase (NOS) in the primate cerebral artery nervi vasorum and to examine the potential role of NOS in cerebral vasospasm after subarachnoid hemorrhage (SAH) in primates, the distribution of NOS immunoreactivity (NOS-IR) in the major cerebral arteries was examined immunohistochemically in cynomolgus monkeys by the use of whole, mounted preparations of the circle of Willis. In four normal monkeys, NOS-IR was localized to the endothelial and adventitial layers of the large cerebral arteries. On the abluminal side, NOS-IR staining was densely concentrated in perivascular nerve fibers (nervi vasorum) of the anterior circulation. Staining was less prominent in the posterior circulation. In six monkeys with vasospasm on Day 7 after placement of preclotted arterial blood to form an SAH around the right middle cerebral artery (MCA) (42% +/- 8.3% decrease of MCA area, mean +/- standard deviation), NOS-IR was virtually absent in nerve fibers around the spastic right MCA but was normal on the contralateral side. In five monkeys in which vasospasm resolved by Day 14 after SAH (36% +/- 14% decrease of right MCA area on Day 7, and 5% +/- 14% decrease on Day 14), NOS-IR was also absent in the right MCA adventitial nerve fibers and remained normal in the left MCA. Adventitial NOS-IR was also normal in cerebral vessels of a sham-operated, nonspastic monkey. These findings provide further evidence that nitric oxide (NO) functions as a neuronal transmitter to mediate vasodilation in primates and indicate a role for adventitial NO in the pathogenesis of cerebral vasospasm after SAH in humans.
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Affiliation(s)
- R M Pluta
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, 20892, USA
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Abstract
The authors sought to develop a model for assessing in vivo regulation of cerebral vasoregulation by nitric oxide (NO), originally described as endothelial-derived relaxing factor, and to use this model to establish the role of NO in the regulation of cerebral blood flow (CBF) in primates. By using regional intraarterial perfusion, the function of NO in cerebral vasoregulation was examined without producing confounding systemic physiological effects. Issues examined were: whether resting vasomotor tone requires NO; whether NO mediates vasodilation during chemoregulation and autoregulation of CBF; and whether there is a relationship between the degree of hypercapnia and hypotension and NO production. Twelve anesthetized (0.5% isoflurane) cynomolgus monkeys were monitored continuously for cortical CBF, PaCO2, and mean arterial pressure (MAP), which were systematically altered to provide control and experimental curves of chemoregulation (CBF vs. PaCO2) and autoregulation (CBF vs. MAP) during continuous intracarotid infusion of 1) saline and 2) an NO synthase inhibitor (NOSI), either L-n-monomethyl arginine or nitro L-arginine. During basal conditions (PaCO2 of 38-42 mm Hg) NOSI infusion of internal carotid artery (ICA) reduced cortical CBF from 62 (saline) to 53 ml/100 g/per minute (p<0.01), although there was no effect on MAP. Increased CBF in response to hypercapnia was completely blocked by ICA NOSI. The difference in regional (r)CBF between ICA saline and NOSI infusion increased linearly with PaCO2 when PaCO2 was greater than 40 mm Hg, indicating a graded relationship of NO production, increasing PaCO2, and increasing CBF. Diminution of CBF with NOSI infusion was reversed by simultaneous ICA infusion of L-arginine, indicating a direct role of NO synthesis in the chemoregulation of CBF. Hypotension and hypertension were induced with trimethaphan camsylate (Arfonad) and phenylephrine at constant PaCO2 (40 +/- 1 mm Hg). Autoregulation in response to changes in MAP from 50 to 140 mm Hg was unaffected by ICA infusion of NOSI. In primates, cerebral vascular tone is modulated in vivo by NO; continuous release of NO is necessary to maintain homeostatic cerebral vasodilation; vasodilation during chemoregulation of CBF is mediated directly by NO production; autoregulatory vasodilation with hypertension is not mediated by NO; and increasing PaCO2 induces increased NO production.
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Affiliation(s)
- B G Thompson
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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Affiliation(s)
- M E Williams
- Program on Aging, School of Medicine, University of North Carolina at Chapel Hill 27599-7550, USA
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Afshar JK, Pluta RM, Boock RJ, Thompson BG, Oldfield EH. Effect of intracarotid nitric oxide on primate cerebral vasospasm after subarachnoid hemorrhage. J Neurosurg 1995; 83:118-22. [PMID: 7782826 DOI: 10.3171/jns.1995.83.1.0118] [Citation(s) in RCA: 113] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The continuous release of nitric oxide (NO) is required to maintain basal cerebrovascular tone. Oxyhemoglobin, a putative spasmogen, rapidly binds NO, implicating loss of NO in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage (SAH). If vasospasm is mediated by depletion of NO in the vessel wall, it should be reversible by replacement with NO. To investigate this hypothesis, the authors placed blood clots around the right middle cerebral artery (RMCA) of four cynomolgus monkeys; four unoperated animals served as controls. Arteriography was performed before and 7 days after surgery to assess the presence and degree of vasospasm, which was quantified in the anteroposterior (AP) projection by computerized image analysis. On Day 7, cortical cerebral blood flow (CBF) in the distribution of the right MCA was measured during four to six runs in the right internal carotid artery (ICA) of brief infusions of saline followed by NO solution. Arteriography was performed immediately after completing the final NO infusion in three of the four animals with vasospasm. Right MCA blood flow velocities were obtained using transcranial Doppler before, during, and after NO infusion in two vasospastic animals. After ICA NO infusion, arteriographic vasospasm resolved (mean percent of preoperative AP area, 55.9%); that is, the AP areas of the proximal portion of the right MCA returned to their preoperative values (mean 91.4%; range 88%-96%). Compared to ICA saline, during ICA NO infusion CBF increased 7% in control animals and 19% in vasospastic animals (p < 0.002) without significant changes in other physiological parameters. During NO infusion, peak systolic right MCA CBF velocity decreased (130 to 109 cm/sec and 116 to 76 cm/sec) in two vasospastic animals. The effects of ICA NO on CBF and CBF velocity disappeared shortly after terminating NO infusion. Intracarotid infusion of NO in a primate model of vasospasm 1) increases CBF, 2) decreases cerebral vascular resistance, 3) reverses arteriographic vasospasm, and 4) decreases CBF velocity in the vasospastic artery without producing systemic hypotension. These findings indicate the potential for the development of targeted therapy to reverse cerebral vasospasm after SAH.
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Affiliation(s)
- J K Afshar
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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Villeneuve PE, Wenger KS, Thompson BG, Kedar T, Dunlop EH. Development of a CELSS bioreactor: oxygen transfer and micromixing in parabolic flight. Adv Space Res 1994; 14:75-78. [PMID: 11540221 DOI: 10.1016/0273-1177(94)90282-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The gas exchange portion of a phase-separated loop bioreactor was tested with respect to oxygen mass transfer and micromixing in accelerations of 0.01g, 1g, and 2g. A plot of the overall mass transfer coefficient versus gravity indicates the rate of oxygen transfer does not change as a function of acceleration. Also, it was determined that the micromixing did not exhibit significant changes in the various gravitational fields. These observations indicate the loop bioreactor should function independent of acceleration.
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Affiliation(s)
- P E Villeneuve
- Colorado State University, Department of Ag. and Chem. Engineering, Fort Collins 80523, USA
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Golfinos JG, Thompson BG, Zabramski JM, Spetzler RF. Are the calcium antagonists really useful in cerebral aneurysmal surgery? A retrospective study. Neurosurgery 1994; 35:541-2. [PMID: 7800152 DOI: 10.1227/00006123-199409000-00037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
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Abstract
Cranial dural arteriovenous fistulae (AVF's) of the tentorial incisura or the dura of the middle fossa have a much higher incidence of draining via leptomeningeal veins than do AVF's of the transverse-sigmoid sinuses or the cavernous sinus. Such a drainage pattern is associated with an increased incidence of intracranial hemorrhage and progressive focal neurological deficits. Patients with cranial dural AVF's often undergo surgical excision and/or endovascular embolization for elimination of the AVF. Since these lesions are frequently large and involve the skull base or adjacent dural sinuses, extensive surgery is often required. In contrast, spinal dural AVF's with only intradural venous drainage to the medullary venous system are treated successfully by simply interrupting the vein that drains the dural AVF as it enters the subarachnoid space. The authors identified a subgroup of patients with cranial dural AVF's in whom the AVF was drained only by leptomeningeal veins, and sought to establish whether simple interruption of the vein draining the blood from the AVF into the subarachnoid space is effective and lasting treatment in this subgroup of patients, as it is in patients with spinal dural AVF's. Four adult patients with symptomatic cranial dural AVF's (two petrotentorial, one middle fossa floor, and one posterior fossa base) were identified on arteriography as having fistulae that were supplied by the internal and/or external carotid arteries and drained only via leptomeningeal veins (two entered the petrosal vein, one a cerebellar hemispheric vein, and one a mesencephalic vein). All patients underwent interruption of the vein draining the dural AVF as it penetrated the dura to enter the subarachnoid space, and experienced neurological improvement after surgery. Repeat arteriography at 1 to 2 weeks (three patients), 3 months (3 patients), 12 to 15 months (three patients), and 4 years (two patients) revealed no residual AVF and no evidence of abnormal blood flow. Many cranial dural AVF's with leptomeningeal venous drainage (the type with the most aggressive behavior) are drained only by leptomeningeal veins. This subgroup of patients can be identified by selective arteriography and requires only interruption of the draining vein as it enters the subarachnoid space for successful, lasting elimination.
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Affiliation(s)
- B G Thompson
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
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Macaloney G, Hall JW, Rollins MJ, Draper I, Thompson BG, McNeil B. Monitoring biomass and glycerol in an Escherichia coli fermentation using near-infrared spectroscopy. ACTA ACUST UNITED AC 1994. [DOI: 10.1007/bf00155422] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Lu GZ, Gray MR, Thompson BG. Physical modeling of animal cell damage by hydrodynamic forces in suspension cultures. Biotechnol Bioeng 1992; 40:1277-81. [DOI: 10.1002/bit.260401018] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Namdev PK, Thompson BG, Ward DB, Gray MR. Effects of glucose fluctuations on synchrony in fed-batch fermentation of Saccharomyces cerevisiae. Biotechnol Prog 1992. [DOI: 10.1021/bp00018a005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
This is a report of a primary extraosseous osteogenic sarcoma of the lung. The patient presented with fever and productive cough. Chest radiography and CT showed a cavitary lesion with an air-fluid level. The lesion was treated as an abscess. Despite aggressive antibiotic therapy and drainage, the patient continued to deteriorate rapidly. At autopsy the lesion was found to be a primary extraosseous pulmonary osteogenic sarcoma.
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Affiliation(s)
- M Bhalla
- Department of Radiology, Massachusetts General Hospital, Boston 02114
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Yegneswaran PK, Gray MR, Thompson BG. Effect of dissolved oxygen control on growth and antibiotic production in Streptomyces clavuligerus fermentations. Biotechnol Prog 1991; 7:246-50. [PMID: 1367597 DOI: 10.1021/bp00009a008] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A proportional-integral control system was used to control dissolved oxygen in a fermentor at constant shear and mass transfer conditions. Growth and antibiotic production in Streptomyces clavuligerus were studied at different dissolved oxygen levels during the fermentation. Three protocols were employed: no-oxygen control to provide a base case, oxygen controlled to a preset saturation level throughout the fermentation, and oxygen controlled at a high level only during the growth phase. The last protocol was aimed at optimizing the consumption of oxygen. Lower specific growth rates and cephamycin C yields were obtained when dissolved oxygen was controlled at 50% throughout the fermentation, compared to the base case. A 2.4-fold increase in the final cephamycin yield was observed when dissolved oxygen was controlled at saturation levels during the growth phase, compared to the experiments without dissolved oxygen control. This enhancement in yield was independent of the dissolved oxygen (DO) level after exponential growth, in the range of 50-100% saturation. The most effective control strategy, therefore, was to control DO only during active growth when the biosynthetic enzymes were probably synthesized.
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Affiliation(s)
- P K Yegneswaran
- Department of Chemical Engineering, University of Alberta, Edmonton, Canada
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Namdev PK, Yegneswaran PK, Gray MR, Thompson BG. Experimental simulation of large-scale bioreaetor environments using a Monte Carlo method. CAN J CHEM ENG 1991. [DOI: 10.1002/cjce.5450690216] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Thompson BG, Coffey RJ, Flickinger JC, Lunsford LD. Stereotactic radiosurgery of small intracranial tumors: neuropathological correlation in three patients. Surg Neurol 1990; 33:96-104. [PMID: 2154869 DOI: 10.1016/0090-3019(90)90018-k] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The mechanism by which radiosurgery can stop the growth of some tumors is poorly understood, in part because postmortem neuropathological findings in patients have been reported only rarely. To define further the effects of radiosurgery, we present the correlation among clinical, neuroimaging, and neuropathological data in three patients with different intracranial tumors who died between 2 and 39 weeks after radiosurgery. The target volumes in two patients with malignant tumors showed sharply demarcated coagulative necrosis. In the third patient, who had a benign acoustic nerve tumor, neuropathological examination found intratumoral hemorrhage and cyst formation, but no necrosis. Radiosurgery appears to cause acute necrosis of malignant cells, although its effectiveness may be limited by the infiltrative nature of some tumors. In benign tumors, necrosis following radiosurgery is relatively delayed, and may not be required for growth arrest.
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Affiliation(s)
- B G Thompson
- Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pennsylvania
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Thompson BG. Controlled ecological life support systems (CELSS) in high pressure environments. Acta Astronaut 1989; 19:463-465. [PMID: 11541157 DOI: 10.1016/0094-5765(89)90112-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Future space habitats may be constructed in high pressure environments. The biological components of any controlled ecological life support systems (CELSS) used in these habitats will have to be able to grow and metabolize normally for the CELSS to operate.
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Affiliation(s)
- B G Thompson
- Biotechnology Department, Alberta Research Council, Edmonton, Canada
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Abstract
Lemna minor (common duckweed) and a Wolffia sp. were grown in submerged growth systems. Submerged growth increased the productivity unit volume (P/UV) of the organisms and may allow these plants to be used in a controlled ecological life support system (CELSS).
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Affiliation(s)
- B G Thompson
- Biotechnology Department, Alberta Research Council, Edmonton, Canada
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Abstract
The effects of low gravity, as produced by a reduced gravity aircraft, the KC135, on the formation and coalescence of gas bubbles were examined over a range of gas-liquid ratios and with various medium constituents. These effects will influence design considerations of fermentors operating in reduced gravity conditions.
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Affiliation(s)
- B G Thompson
- Biotechnology Department, Alberta Research Council, Edmonton, Canada
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Delany DJ, Scatliff JH, Thompson BG. A multimodality projection console for the radiology conference room. Invest Radiol 1987; 22:336-7. [PMID: 3583654 DOI: 10.1097/00004424-198704000-00010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A multimodality projection console for the radiology conference room is described. The configuration of the TV camera, view boxes, switches, and adjacent lectern allows better transmission and easier manipulation of images during consultation and lecture sessions with the faculty, and house officers.
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Abstract
Mutations occur at a higher rate in space than under terrestrial conditions, primarily due to an increase in radiation levels. These mutations may effect the productivity of plants found in a controlled ecological life support system (CELSS). Computer simulations of plants with different ploidies, modes of reproduction, lethality thresholds, viability thresholds and susceptibilities to radiation induced mutations were performed under space normal and solar flare conditions. These simulations identified plant characteristics that would enable plants to retain high productivities over time in a CELSS.
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Affiliation(s)
- B G Thompson
- Biotechnology Department, Alberta Research Council, Edmonton, Canada
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Affiliation(s)
- B G Thompson
- Department of Biotechnology, Alberta Research Council, 11315-87 Avenue, Edmonton, Alberta, T6G 2C2 Canada
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Abstract
A nitrate control system has been devised for the maintenance of stable nitrate concentrations throughout fed-batch fermentations of Corynebacterium glutamicum. The feedback control system was based on the use of a nitrate-ion-selective electrode to directly monitor the nitrate levels in the fermentor and an automatic controller to activate a nitrate feed pump. The electrode which was used for controlling the nitrate level was stable through-out the fermentation period. The apparent maximum specific growth rate, biomass production, protein production, biomass yields on glucose and nitrate, and amino acid production were all optimal at approximately 50mM nitrate.
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Affiliation(s)
- M M Kole
- Alberta Research Council, Biotechnology Department, 250 Karl Clark Rd., Edmonton, Alberta, Canada T6H 5X2
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Thompson BG, Ward D. Gas transfer in microgravity fermentations. Acta Astronaut 1986; 13:105-117. [PMID: 11542837 DOI: 10.1016/0094-5765(86)90041-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Fermentations performed under microgravity conditions may be used in future long duration space missions for recycling expendable life support materials. These fermentations will differ from similar fermentations performed at one gravity in the manner in which gas transfer in the fermentor is carried out.
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Affiliation(s)
- B G Thompson
- Department of Biotechnology, Alberta Research Council, Edmonton, Canada
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Staab EV, Perry JR, Brenton BC, Thompson BG, Parrish DM, Creasy JL, Yankaskas BC. Image communications. What is needed and why. Appl Radiol 1985; 14:19-20, 25-9. [PMID: 10280628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Better communications are essential in the new medical environment. Methods to make more efficient the throughput in an existing department, foster confidence of patients, and improve the communications and efficiency of referring physicians are needed. The most difficult and thus the driving component of the new communications environment is image transmission. Concepts of picture archiving and communications systems, or PACS, arising from digital technology make possible unique and ubiquitous solutions to image communications. Better quality control and improved interpretation throughout the system, including the offices of referring physicians, will be possible. Radiologists are in a position to mold this new medical industry.
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