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Leavitt ML, Pieper F, Sachs AJ, Martinez-Trujillo JC. A Quadrantic Bias in Prefrontal Representation of Visual-Mnemonic Space. Cereb Cortex 2017; 28:2405-2421. [DOI: 10.1093/cercor/bhx142] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Indexed: 11/13/2022] Open
Affiliation(s)
- Matthew L Leavitt
- Department of Physiology, McGill University, Montreal, Quebec, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, Ontario, Canada
| | - Florian Pieper
- Department of Neuro- & Pathophysiology, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Adam J Sachs
- Division of Neurosurgery, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Julio C Martinez-Trujillo
- Department of Physiology, McGill University, Montreal, Quebec, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, Ontario, Canada
- Robarts Research Institute, University of Western Ontario, Ontario, Canada
- Brain and Mind Institute, University of Western Ontario, Ontario, Canada
- Department of Psychiatry, University of Western Ontario, Ontario, Canada
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Leavitt ML, Mendoza-Halliday D, Martinez-Trujillo JC. Sustained Activity Encoding Working Memories: Not Fully Distributed. Trends Neurosci 2017; 40:328-346. [PMID: 28515011 DOI: 10.1016/j.tins.2017.04.004] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 04/14/2017] [Accepted: 04/18/2017] [Indexed: 10/19/2022]
Abstract
Working memory (WM) is the ability to remember and manipulate information for short time intervals. Recent studies have proposed that sustained firing encoding the contents of WM is ubiquitous across cortical neurons. We review here the collective evidence supporting this claim. A variety of studies report that neurons in prefrontal, parietal, and inferotemporal association cortices show robust sustained activity encoding the location and features of memoranda during WM tasks. However, reports of WM-related sustained activity in early sensory areas are rare, and typically lack stimulus specificity. We propose that robust sustained activity that can support WM coding arises as a property of association cortices downstream from the early stages of sensory processing.
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Affiliation(s)
- Matthew L Leavitt
- Department of Physiology, McGill University, Montreal, QC H3G 1Y6, Canada.
| | - Diego Mendoza-Halliday
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Julio C Martinez-Trujillo
- Robarts Research Institute, Brain and Mind Institute, Department of Psychiatry, and Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5B7, Canada.
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Leavitt ML, Pieper F, Sachs A, Joober R, Martinez-Trujillo JC. Structure of spike count correlations reveals functional interactions between neurons in dorsolateral prefrontal cortex area 8a of behaving primates. PLoS One 2013; 8:e61503. [PMID: 23630595 PMCID: PMC3632589 DOI: 10.1371/journal.pone.0061503] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Accepted: 03/11/2013] [Indexed: 11/25/2022] Open
Abstract
Neurons within the primate dorsolateral prefrontal cortex (dlPFC) are clustered in microcolumns according to their visuospatial tuning. One issue that remains poorly investigated is how this anatomical arrangement influences functional interactions between neurons during behavior. To investigate this question we implanted 4 mm×4 mm multielectrode arrays in two macaques' dlPFC area 8a and measured spike count correlations (rsc) between responses of simultaneously recorded neurons when animals maintained stationary gaze. Positive and negative rsc were significantly higher than predicted by chance across a wide range of inter-neuron distances (from 0.4 to 4 mm). Positive rsc were stronger between neurons with receptive fields (RFs) separated by ≤90° of angular distance and progressively decreased as a function of inter-neuron physical distance. Negative rsc were stronger between neurons with RFs separated by >90° and increased as a function of inter-neuron distance. Our results show that short- and long-range functional interactions between dlPFC neurons depend on the physical distance between them and the relationship between their visuospatial tuning preferences. Neurons with similar visuospatial tuning show positive rsc that decay with inter-neuron distance, suggestive of excitatory interactions within and between adjacent microcolumns. Neurons with dissimilar tuning from spatially segregated microcolumns show negative rsc that increase with inter-neuron distance, suggestive of inhibitory interactions. This pattern of results shows that functional interactions between prefrontal neurons closely follow the pattern of connectivity reported in anatomical studies. Such interactions may be important for the role of the prefrontal cortex in the allocation of attention to targets in the presence of competing distracters.
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Affiliation(s)
- Matthew L. Leavitt
- Cognitive Neurophysiology Laboratory, Department of Physiology, McGill University, Montréal, Canada
| | - Florian Pieper
- Institute for Neuro- & Pathophysiology, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Adam Sachs
- Division of Neurosurgery, Department of Surgery, The Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Canada
| | - Ridha Joober
- Douglas Institute, Department of Psychiatry, McGill University, Montreal, Canada
| | - Julio C. Martinez-Trujillo
- Cognitive Neurophysiology Laboratory, Department of Physiology, McGill University, Montréal, Canada
- * E-mail:
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Sekaran P, Ehrlich MP, Hagl C, Leavitt ML, Jacobs R, McCullough JN, Bennett-Guerrero E, Ehrlich M. A comparison of complete blood replacement with varying hematocrit levels on neurological recovery in a porcine model of profound hypothermic (<5 degrees C) circulatory arrest. Anesth Analg 2001; 92:329-34. [PMID: 11159225 DOI: 10.1097/00000539-200102000-00008] [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] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Profound hypothermia (<5 degrees C) may afford better neurological protection after circulatory arrest; however, there are theoretical concerns related to microcirculatory sludging of blood components at these ultra-low temperatures. We hypothesized that at temperatures <5 degrees C, complete blood replacement results in superior neurological outcome. Twelve Yorkshire pigs (30 kg) underwent thoracotomy, cardiopulmonary bypass (CPB), and were randomly assigned to one of three target hematocrits during circulatory arrest: 0%, 5%, 15%. Hextend (6% hetastarch in a balanced electrolyte vehicle) was used for the CPB prime and as an exchange fluid. Animals were cooled to a temperature <5 degrees C, underwent 1-h circulatory arrest, and were warmed to 35 degrees C with administration of blood to increase the hematocrit to >25% before separation from CPB. The primary outcome, peak postoperative neurobehavioral score, was compared between groups. The 0% group (mean +/- SD) had significantly (P: < 0.02) better neurobehavioral scores than the 5% and 15% groups (6.0 +/- 2.9 vs 1.3 +/- 1.0 and 1.5 +/- 0.6) respectively. Other variables (e.g., intracranial pressure) were similar between groups. In a porcine model of profound hypothermia (<5 degrees C) and circulatory arrest, complete blood replacement resulted in superior neurological outcome. This finding suggests that at ultralow temperatures, the presence of some blood component (e.g., erythrocytes, leukocytes) may be deleterious.
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Affiliation(s)
- P Sekaran
- Department of Anesthesiology, The Mount Sinai School of Medicine, New York, New York, USA
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Taylor MJ, Bailes JE, Elrifai AM, Shih SR, Teeple E, Leavitt ML, Baust JG, Maroon JC. A new solution for life without blood. Asanguineous low-flow perfusion of a whole-body perfusate during 3 hours of cardiac arrest and profound hypothermia. Circulation 1995; 91:431-44. [PMID: 7805248 DOI: 10.1161/01.cir.91.2.431] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
BACKGROUND The benefits of hypothermia for preventing ischemic injury are well known, but its application in surgery to protect the whole body during procedures requiring circulatory arrest is currently limited to < 1 hour at 15 degrees C using 50% hemodilution. In a significant departure from previous methods, we have developed a technique of asanguineous blood substitution with low-flow perfusion and cardiac arrest at < 10 degrees C in a canine model. Our approach has been to design a hypothermic blood substitute that would protect the brain and visceral organs during several hours of bloodless perfusion. Two different solutions have been designed to fulfill separate requirements in the procedure. METHODS AND RESULTS With the use of extracorporeal cardiac bypass, 14 adult dogs were exsanguinated during cooling; 11 dogs were blood substituted using in combination the "purge" and "maintenance" solutions (group 1), and 3 dogs were perfused throughout with the "purge" solution alone as controls (group 2). After cardiac arrest, the solutions were continuously circulated for 3 1/2 hours by the extracorporeal pump (flow rate, 40 to 85 mL.kg-1.min-1; mean arterial blood pressure, 25 to 40 mm Hg). The temperature was maintained at < 10 degrees C (nadir, 6.6 +/- 0.1 degrees C) for 3 hours, and the hematocrit was kept at < 1% before controlled rewarming and autotransfusion. In the experimental group, the heart always started spontaneously in the temperature range of 11 degrees C to 27 degrees C, and 8 animals have survived long-term (current range, 14 to 110 weeks) without any detectable neurological deficit. In contrast, two control animals survived after extensive and aggressive cardiac resuscitation efforts; after surgery they exhibited transient motor and sensory deficits for approximately 1 week. Evaluation of biochemical and hematological parameters showed only a transient and inconsequential elevation in enzymes (eg, brain, liver, cardiac) in group 1 compared with the markedly greater elevations in group 2. For example, immediate postoperative values (mean +/- SEM) for lactate dehydrogenase were 114 +/- 10 for group 1 versus 490 +/- 210 for group 2 (P < .03); for SGOT, values were 93 +/- 18 for group 1 versus 734 +/- 540 for group 2 (P < .05). On day 1 for creatine kinase (CK), the group 1 value was 7841 +/- 2307 versus 71,550 +/- 2658 for group 2 (P = .03), and for CK-BB, the group 1 value was 108 +/- 22 versus 617 +/- 154 for group 2 (P = .03). Neurological evaluation using deficit scores (NDS) was based on a modification of the Glasgow Coma Scale score: 0, normal; 1, minimal abnormality; 2, weakness; 3, paralysis; 4, coma; and 5, death. At days 1 and 2 after surgery, NDS (mean +/- SEM) were 0 +/- 0 for the experimental group versus 1.5 +/- 0.5 for the control group. At days 3 and 7 after surgery, NDS were 0 +/- 0 for group 1 versus 1.0 +/- 1.0 for group 2. CONCLUSIONS The faster neurological recovery of dogs treated with the "intracellular-type" maintenance solution supports the biochemical data showing the benefits of this type of blood substitute for extending the safe limits of hypothermic cardiac arrest procedures to > 3 hours.
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Affiliation(s)
- M J Taylor
- Department of Neurosurgery Research, Allegheny-Singer Research Institute, Pittsburgh, PA 15212
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Taylor MJ, Bailes JE, Elrifai AM, Shih TS, Teeple E, Leavitt ML, Baust JC, Maroon JC. Asanguineous whole body perfusion with a new intracellular acellular solution and ultraprofound hypothermia provides cellular protection during 3.5 hours of cardiac arrest in a canine model. ASAIO J 1994; 40:M351-8. [PMID: 8555538 DOI: 10.1097/00002480-199407000-00022] [Citation(s) in RCA: 15] [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: 01/31/2023] Open
Abstract
Temporary cessation of blood flow is a necessary aid for certain complex neurosurgical and cardiovascular procedures, and hypothermia is often used to help protect against the deleterious effects of ischemia and anoxia. In an attempt to protect cellular integrity during ultraprofound hypothermia (< 10 degrees C) and complete blood substitution, two new crystalloid-colloid blood substitutes (Hypothermosol-maintenance [HTS-M] and Hypothermosol-purge [HTS-P]) have been evaluated. Using extracorporeal bypass, 14 dogs were totally exsanguinated during cooling using the HTS-P solution, then perfused (40-85 ml/kg/min; mean arterial blood pressure = 25-40 mmHg) with either TS-M (Group I, n = 11), or with HTS-P as controls (Group II, n = 3) for 3 hr at 7 degrees C. During warming, the dogs were autotransfused and observed neurologically and biochemically during recovery. All dogs in Group I recovered and eight have survived long term (12-80 weeks) without apparent neurologic deficits. In contrast, dogs in Group II were more difficult to revive (cardiac resuscitation); two survived long term with delayed neurologic recovery. Evaluation of biochemical parameters showed only a transient and inconsequential elevation in enzymes (e.g., brain, liver, and heart) in Group I compared with the markedly greater elevations in Group II. The faster neurologic recovery of dogs treated with the "intracellular" maintenance solution supports the biochemical data showing the benefits of this type of blood substitute for extending the safe limits of hypothermic cardiac arrest to beyond 3 hr.
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Affiliation(s)
- M J Taylor
- Neurosciences Research Center, Allegheny-Singer Research Institute, Pittsburgh, PA 15212, USA
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Abstract
The authors report dose-response relationships for atropine in their rat model of human delirium. In this model, anticholinergic mechanisms are an important cause and may be a neurochemical final common pathway for diverse etiologies of delirium. Four intravenous (i.v.) bolus doses of atropine (27.5, 13.5, 6.875, and 3.44 mg/kg) were studied along with the originally reported dose of 55 mg/kg and saline control. Subsequent iv infusions were also proportionately reduced. EEG frequency and amplitude, maze performance, and subjective behavioral descriptions were taken over 320-minute study periods. Repeated-measures analysis of variance compared data between groups, and effect sizes were calculated. Dosages to be used in future studies are discussed.
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Affiliation(s)
- M L Leavitt
- Medical College of Pennsylvania, Allegheny-Singer Research Institute, Pittsburgh
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Elrifai AM, Bailes JE, Shih SR, Maroon JC, Leavitt ML, Teeple E, Loesch DV, Cottington EM, Taylor MJ, Bazmi B. Rewarming, ultraprofound hypothermia and cardiopulmonary bypass. J Extra Corpor Technol 1992; 24:107-12. [PMID: 10148321] [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] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Rewarming, a key event in resuscitation from accidental, experimental and clinical hypothermia, is sometimes followed by neurologic, cardiac, and respiratory sequelae and may lead to death. The rate of rewarming has been implicated but not quantified as etiologic in these sequelae. Under anesthesia fifteen dogs were cannulated and connected to an extracorporeal circuit for oxygenation, core cooling and rewarming. They were subjected to ultra-profound hypothermia with a core (esophageal) temperature as low as 1.3 degrees C, cardiac arrest, blood substitution, and continuous low flow perfusion. After 2-3 hours of cardiac arrest, rewarming began. Mechanical activity of the heart was seen between 10 degrees and 28 degrees C and respiration resumed at 29 degrees C. The rewarming rates of the 15 dogs were retrospectively studied. They were placed into three categories (G) based on the outcome. G-I (N=2):no neurological complications, G-II (N=8):transient neurological problems, and G-III (N=5):death, mainly from cardiovascular and respiratory complications confirmed at death by autopsy. Heat gain by each animal was recorded as a function of time for all experiments. The time it took each dog to reach 35 degrees C was determined and a mean was calculated (rewarming rate). Normal body temperature for a dog is 37.8 degrees C. Statistical analysis (ANOVA) was performed ex post facto to determine the relationship between rewarming rate and outcome. Our data contradicts the notion that slow core rewarming from nadir to normal temperature offers better outcome.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- A M Elrifai
- Department of Neurosurgery, Allegheny-Singer Research Institute, Pennsylvania 15212
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Leavitt ML, Bailes JE, Elrifai AM, Teeple E, Shih TS, Ciongoli K, Devenyi C, Bazmi B, Maroon JC. Comparison of the effects of total blood substitution during two different levels of hypothermic cardiac arrest. Biomater Artif Cells Immobilization Biotechnol 1992; 20:963-72. [PMID: 1391541 DOI: 10.3109/10731199209119749] [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: 12/26/2022]
Abstract
The effect of total blood replacement with a solution containing neither hemoglobin nor fluorocarbon was studied under two different levels of hypothermia. Ten dogs were anesthetized and esophageal temperature lowered to about 24 degrees at which time exsanguination began. Upon cardiac arrest and the completion of exsanguination, continuous whole body closed chest extracorporeal circulation of an oxygenated blood substitute was begun. Hematocrit was 1% while core temperature remained less than 10 degrees C for 3 hours of perfusion during which nadirs of 1.3 degrees C (Group I, N = 5) and 7.3 degrees (Group II, N = 5) were achieved. Replacement of the perfusate with whole blood began once the dog was rewarmed to approximately 10 degrees C. All dogs survived the procedure. Two dogs from each group died by the fourth post-operative day but the others survived long term. Group II showed a faster return to normal based on motor behavioral, biochemical and hematological changes. Thus the combination of profound hypothermia and complete blood substitution with a solution lacking any special oxygen carrying molecule, can be tolerated for 3 hours using both levels of hypothermia, however, the warmer one appears to be associated with faster recovery.
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Affiliation(s)
- M L Leavitt
- Allegheny-Singer Research Inst., Allegheny General Hospital, Pittsburgh, PA
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Leavitt ML, Bailes JE, Shih TS, Elrifai AM, Teeple E, Ciongoli K, Devenyi C, Bazmi B, Maroon JC. Complete blood substitution during profound hypothermic cardiac arrest in dogs. Biomater Artif Cells Immobilization Biotechnol 1992; 20:1063-7. [PMID: 1391427 DOI: 10.3109/10731199209119764] [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: 12/26/2022]
Abstract
This study compared the effects of 3 hours of cardiac arrest performed at 2 different levels of profound hypothermia in totally exsanguinated, blood substituted dogs. Dogs (N = 10) were anesthetized and esophageal temperature was lowered to 24 degrees at which time exsanguination began. Once exsanguination was complete and the heart had arrested, continuous whole body perfusion of an oxygenated blood substitute solution was performed for 3 hours. Core temperature during this period remained below 10 degrees C and reached nadirs of 1.3 degrees C in Group 1 (N = 5) versus 7.3 degrees C in Group II (N = 5). Once the dog was allowed to rewarm to 10 degrees C replacement of the perfusate with blood was begun. All dogs survived the procedure but 2 dogs from each group died by 4 days following the experiment. The remaining 6 dogs were observed for between 10 and 85 days. The group perfused with blood substitute at the warmer nadir had a faster recovery of motor behavior and showed smaller changes from normal in several biochemical and hematological parameters. These findings indicate that profound hypothermia and total blood substitution can be successfully achieved at either temperature nadir, but the warmer level appears to be associated with a faster recovery.
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Affiliation(s)
- M L Leavitt
- Allegheny-Singer Research Institute, Allegheny General Hospital, Pittsburgh, Pennsylvania
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Elrifai AM, Bailes JE, Leavitt ML, Teeple E, Shih SR, Taylor MJ, Maroon JC, Ciongoli KA, Bazmi B, Devenyi C. Blood substitution: an experimental study. J Extra Corpor Technol 1991; 24:58-63. [PMID: 10147908] [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] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Priming fluids for cardiopulmonary bypass have been extremely varied, with resultant hemodilution. Furthermore, major surgeries utilizing cardiopulmonary bypass require multiple postoperative transfusions of blood and blood products. The appeal of having a readily available blood substitute for major cardiovascular and neurosurgical operations could prove to be a life saver, while also eliminating the risk of diseases transmitted by transfusion. Blood substitutes could also lessen the reported complications resulting from blood damage due to prolonged circulation of the blood by the extracorporeal pump. A technique was examined in 15 dogs using hypothermia for maximum metabolic suppression, incorporating an aqueous blood substitute (Cryomedical Sciences, Inc., Rockville, MD). The anesthetized animals were cannulated for extracorporeal pump oxygenation. As temperature was lowered the dogs were exsanguinated and volume replaced with blood substitute to lower the hematocrit to less than 1%. After 3 hours of cardiac arrest and continuous perfusion at a core temperature less than 10 degrees C, rewarming began. When temperature reached greater than or equal to 10 degrees C, the blood substitute was drained and the animals were autotransfused. The heart was started at 15 degrees C and spontaneous respiration resumed at 29 degrees C. Using the first generation blood substitute the survival rate was maximal (100%) at 2.5 hrs under 10 degrees C and 3 hours of cardiac arrest. Research is underway on a new blood substitute, which is to serve as a universal hypothermic preservation solution (in situ organ preservation).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- A M Elrifai
- Allegheny-Singer Research Institute, Pittsburgh, PA 15212
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Young JW, Conte ET, Leavitt ML, Nafz MA, Schroeter AL. Cutaneous immunopathology of androgenetic alopecia. J Am Osteopath Assoc 1991; 91:765-71. [PMID: 1744007] [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] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Male pattern baldness is assumed to result from a combination of normal serum concentrations of androgen and an appropriate genetic background. To study whether inflammation contributes to the development of androgenetic alopecia, direct immunofluorescence and dermatopathologic studies were performed on biopsy specimens from bald scalp of patients, with specimens from uninvolved scalp of these patients or from scalp of volunteers who were not bald serving as controls. Granular deposits of Immunoglobulin M or C3 (or both) were found at the basement membrane in 25 (96%) of 26 study patients and 1 (12%) of 8 control subjects. Granular C3 was also deposited on eccrine myoepithelial cells in 8 (31%) of 26 study patients, but no control subjects. Porphyrins were found in the pilosebaceous canal in 15 (58%) of 26 study subjects and in 1 (12%) of 8 control subjects. These results support an inflammatory pathogenesis of androgenetic alopecia. Propionibacterium acnes is known to produce porphyrins. Ultraviolet radiation may excite microbiologic porphyrins that could activate C3 and, subsequently, the complement cascade producing inflammatory mediators.
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Affiliation(s)
- J W Young
- Department of Dermatology, Grandview Hospital Medical Center, Ohio University College of Osteopathic Medicine, Dayton
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13
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Bailes JE, Leavitt ML, Teeple E, Maroon JC, Shih SR, Marquardt M, Rifai AE, Manack L. Ultraprofound hypothermia with complete blood substitution in a canine model. J Neurosurg 1991; 74:781-8. [PMID: 2013779 DOI: 10.3171/jns.1991.74.5.0781] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [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: 12/29/2022]
Abstract
The potential for hypothermia to prevent or ameliorate ischemic injury to the central nervous system is well known. To determine if a more prolonged period of metabolic suppression with blood substitution is possible, a method was developed to lower body temperature to near the freezing point. Eight adult mongrel dogs underwent closed-chest extracorporeal circulation with both external and internal body cooling. As they were cooled, progressive hemodilution was employed until complete exsanguination and blood substitution with an aqueous solution was accomplished. Continuous circulation and a core temperature at a mean of 1.7 degrees C were maintained from 2 1/2 to 3 hours. After rewarming to 20 degrees C, the animals were autotransfused and allowed to recover. Of the eight animals, two died due to technical factors related to cardiac defibrillation. Of the six surviving animals, five survived over a long period and one died on the 10th postoperative day with hepatorenal failure resulting from a presumed blood transfusion incompatability reaction. All six showed normal neurological function and kennel behavior, except one dog with mild weakness of a hindlimb. When the dogs were sacrificed 1 to 2 months postoperatively, all organs were histologically normal. Specifically, there was no gross or microscopic evidence of ischemic or hypoxic injury to any central nervous system structures. This pilot study demonstrates that it is possible to successfully achieve complete exsanguination, blood substitution, and ultraprofound body temperature, while continuous circulation of the blood substitute is maintained. With the capability of controlling and repeatedly performing washout of the extracellular environment and by reaching lower temperatures, it may be possible to attain greater cellular metabolic suppression. This perhaps will extend the allowable times for circulatory arrest procedures. In addition, "bloodless ischemia" may be beneficial in removing both blood substances and formed elements which may mediate organ ischemia. With replacement of blood at warm temperatures, coagulopathy is avoided. This preliminary evidence demonstrates potential in the combination of ultraprofound hypothermia and complete blood component substitution. However, further study is required to confirm the potential of achieving circulatory arrest of longer duration.
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Affiliation(s)
- J E Bailes
- Department of Neurosurgery, Allegheny General Hospital, Pittsburgh, Pennsylvania
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Leavitt ML, Yudofsky SC, Maroon JC, Riley EJ, Bavitz MB. Effect of intraventricular nadolol infusion on shock-induced aggression in 6-hydroxydopamine-treated rats. J Neuropsychiatry Clin Neurosci 1989; 1:167-72. [PMID: 2521058 DOI: 10.1176/jnp.1.2.167] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Increasingly, beta blockers are being utilized to treat patients with aggressive disorders secondary to brain lesions. To secure further data about the potential efficacy of beta blockers for this condition, a rat model was employed in which aggression was enhanced by 6-hydroxydopamine. Following lesioning of the brain, aggression in the rats increased from an average baseline of 10.9 +/- 2.1 to 42.7 +/- 2.0 fights per testing period. Thereafter, either pharmacologically inert, artificial CSF or nadolol was introduced through transcerebral, intraventricular perfusion with a significant reduction in aggression in the nadolol-treated animals when compared with those receiving artificial CSF.
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Affiliation(s)
- M L Leavitt
- Department of Neuroscience Research, Allegheny-Singer Research Institute, Allegheny General Hospital, Pittsburgh, Pennsylvania 15212
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Hoffman WE, Leavitt ML, Albrecht RF, Miletich DJ. Central cardiovascular activity of prostaglandin E2, prostaglandin F2 alpha and prostacyclin. Prostaglandins 1981; 21:899-904. [PMID: 7027321 DOI: 10.1016/0090-6980(81)90159-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Prostacyclin (PGI2), prostaglandin E2 (PGE2) and prostaglandin F2 alpha (PGF2 alpha) were tested here in unanesthetized male Sprague-Dawley rats for their effects on the cardiovascular system as mediated by the central nervous system. Cannulae were chronically implanted into the third cerebral ventricle, femoral arteries and femoral veins of rats. Both PGE2 and PGF2 alpha induced increased arterial blood pressure and tachycardia by an action on the central nervous system. The changes seen with PGE2 were larger than those observed with PGF2 alpha. Only transient depressor effects were seen with PGI2 and these changes appeared to be due to the leakage of the substance into the peripheral vascular system.
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Abstract
The mechanism by which clonidine suppresses plasma renin activity (PRA) was investigated in dogs anesthetized with pentobarbital. Injection of clonidine (1 micrograms/kg) into the cisterna magna decreased PRA from levels stimulated by prior hemorrhage into a blood reservoir to reduce mean blood pressure by 25% (21.7 ng/ml/hr +/- 6.6 SE leads to 11.1 ng/ml/hr +/- 2.4 SE; p less than 0.05). Clonidine reduced heart rate but mean arterial pressure remained constant due to fluid movement between the reservoir and the arterial circulation of the dog. These effects could not be attributed to leakage of clonidine from the cerebrospinal fluid since intravenous administration of the same dose had no effect on PRA. In animals bilaterally splanchnicotomized at the level of the diaphragm, elevated PRA was not reduced by intracisternal clonidine. When return of reservoir fluid was prevented, animals became hypotensive after central clonidine and renin tended to increase. These results indicate that clonidine reduces stimulated renin by a central mechanism that is dependent upon the integrity of the sympathetic innervation of the kidney. Other stimuli for renin release may override the inhibitory effect of central clonidine.
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