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Sibbing D, Shan J, Bourhis F, Hofer K, Kasireddy E, Qian A, Khan I. Clopidogrel monotherapy following dual antiplatelet therapy in patients with acute coronary syndrome post-drug-eluting stent implantation: a systematic review and direct/indirect treatment comparison. Eur Heart J 2022. [DOI: 10.1093/eurheartj/ehac544.1387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Background
In patients with acute coronary syndromes (ACS) receiving a drug-eluting stent (DES), treatment with dual antiplatelet therapy (DAPT) reduces the risk of recurrent ischemic events. Optimal duration of DAPT depends on patient characteristics and switching to single antiplatelet therapy (SAPT) is recommended after the course of DAPT.
Purpose
The aim of this study was to evaluate the comparative efficacy and safety of switching to clopidogrel SAPT following DAPT in patients with ACS post DES-implantation.
Methods
A systematic literature review (SLR) was conducted by searching MEDLINE®, Embase, and CENTRAL up to July 27, 2021. Randomized controlled trials (RCTs) and observational studies that evaluated clopidogrel SAPT following DAPT in adults with ACS post-DES implantation were included. Heterogeneity of included studies was vetted in a feasibility assessment. Random effects meta-analyses were conducted using the metafor package for R. Direct comparisons were conducted for clopidogrel vs. aspirin and clopidogrel vs. DAPT. Using the Bucher method, aspirin vs. DAPT was indirectly compared by taking the difference between their respective pooled treatment effects vs. clopidogrel. A sensitivity analysis was conducted by including studies with a follow-up of 12 months.
Results
Of 5,349 records identified, seven unique studies (four RCTs and three observational studies) were eligible to be included in the SLR and quantitative treatment comparison. Risk of major adverse cardiovascular events (MACE) was lower in patients who switched to clopidogrel SAPT after DAPT compared with those who switched to aspirin monotherapy (hazard ratio [HR]: 0.72; 95% confidence interval [CI]: 0.54, 0.98), and this difference was significant. No significant difference in risk of MACE was found between switching to clopidogrel SAPT after DAPT and continuation of DAPT (HR: 0.90; 95% CI: 0.65, 1.25). This finding was consistent with the sensitivity analysis representing studies with follow-up of 12 months (HR: 0.95; 95% CI: 0.69, 1.31). Risk of bleeding was not analysed due to insufficient data across included studies for patients with ACS. However, within-study findings from one RCT of 4,136 patients demonstrated a significantly lower risk of bleeding, defined as thrombolysis in myocardial infarction (major and/or minor, for switching to clopidogrel SAPT following DAPT compared with continuation of DAPT (0.54% vs. 1.17% of patients had bleeding [HR: 0.46; 95% CI: 0.23, 0.94]).
Conclusion
Findings from this SLR suggest switching to clopidogrel SAPT after DAPT in ACS post-DES implantation has a lower risk of MACE compared with switching to aspirin monotherapy, and no difference in the risk of MACE compared with continuation of DAPT. There was insufficient data across the included studies to evaluate the bleeding risk, however, a single study indicated a lower bleeding risk with switching to clopidogrel SAPT.
Funding Acknowledgement
Type of funding sources: Private company. Main funding source(s): Sanofi
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Affiliation(s)
- D Sibbing
- Privatklinik Lauterbacher Mühle am Ostersee , Seeshaupt , Germany
| | | | | | - K Hofer
- Evidinno Outcomes Research Inc. , Vancouver , Canada
| | - E Kasireddy
- Evidinno Outcomes Research Inc. , Vancouver , Canada
| | - A Qian
- Evidinno Outcomes Research Inc. , Vancouver , Canada
| | - I Khan
- Sanofi , Bridgewater , United States of America
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Simi H, Gaupmann V, Wallner D, Hofer K, Tuttner S, Amort FM. Quality criteria of generation playgrounds. Eur J Public Health 2017. [DOI: 10.1093/eurpub/ckx189.119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- H Simi
- FH JOANNEUM University of Applied Sciences, Bad Gleichenberg, Austria
| | - V Gaupmann
- FH JOANNEUM University of Applied Sciences, Bad Gleichenberg, Austria
| | - D Wallner
- FH JOANNEUM University of Applied Sciences, Bad Gleichenberg, Austria
| | - K Hofer
- FH JOANNEUM University of Applied Sciences, Bad Gleichenberg, Austria
| | - S Tuttner
- FH JOANNEUM University of Applied Sciences, Bad Gleichenberg, Austria
| | - FM Amort
- FH JOANNEUM University of Applied Sciences, Bad Gleichenberg, Austria
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3
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Hofer K, Jennetten B, Hauer B, Strempfl A. Workplace health promotion through health coaching on styrian farms: outcomes from project evaluation. Eur J Public Health 2016. [DOI: 10.1093/eurpub/ckw166.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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4
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Hofer K, Käfer G. Mixed-Methods-Design als Methode der Prozessevaluation in der lebensweltorientierten Gesundheitsförderung. Gesundheitswesen 2015. [DOI: 10.1055/s-0035-1563106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Hofer K, Amort FM. Partizipation in der Betrieblichen Gesundheitsförderung als Einstiegshilfe für Unternehmen und deren Stakeholder. Gesundheitswesen 2014. [DOI: 10.1055/s-0034-1386925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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6
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Hildner F, Eder MJ, Hofer K, Aberl J, Redl H, van Griensven M, Gabriel C, Peterbauer-Scherb A. Human platelet lysate successfully promotes proliferation and subsequent chondrogenic differentiation of adipose-derived stem cells: a comparison with articular chondrocytes. J Tissue Eng Regen Med 2013; 9:808-18. [PMID: 23303715 DOI: 10.1002/term.1649] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [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: 09/30/2011] [Revised: 07/20/2012] [Accepted: 10/19/2012] [Indexed: 11/10/2022]
Abstract
Fetal calf serum (FCS) bears a potential risk for carrying diseases and eliciting immune reactions. Nevertheless, it still represents the gold standard as medium supplement in cell culture. In the present study, human platelet lysate (PL) was tested as an alternative to FCS for the expansion and subsequent chondrogenic differentiation of human adipose-derived stem cells (ASCs). ASCs were expanded with 10% FCS (group F) or 5% PL (group P). Subsequently, three-dimensional (3D) micromass pellets were created and cultured for 5 weeks in chondrogenic differentiation medium. Additionally, the de- and redifferentiation potential of human articular chondrocytes (HACs) was evaluated and compared to ASCs. Both HACs and ASCs cultured with PL showed strongly enhanced proliferation rates. Redifferentiation of HACs was possible for cells expanded up to 3.3 population doublings (PD). At this stage, PL-expanded HACs demonstrated better redifferentiation potential than FCS-expanded cells. ASCs could also be differentiated following extended passaging. Glycosaminoglycan (GAG) quantification and qRT-PCR of 10 cartilage related markers demonstrated a tendency for increased chondrogenic differentiation of PL-expanded ASCs compared to cells expanded with FCS. Histologically, collagen type II but also collagen type X was mainly present in group P. The present study demonstrates that PL strongly induces proliferation of ASCs, while the chondrogenic differentiation potential is retained. HACs also showed enhanced proliferation and even better redifferentiation when previously expanded with PL. This suggests that PL is superior to FCS as a supplement for the expansion of ASCs and HACs, particularly with regard to chondrogenic (re)differentiation.
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Affiliation(s)
- F Hildner
- Red Cross Blood Transfusion Service of Upper Austria, Linz, Austria.,Austrian Cluster for Tissue Regeneration
| | - M J Eder
- Red Cross Blood Transfusion Service of Upper Austria, Linz, Austria.,Austrian Cluster for Tissue Regeneration
| | - K Hofer
- Red Cross Blood Transfusion Service of Upper Austria, Linz, Austria.,Austrian Cluster for Tissue Regeneration
| | - J Aberl
- Red Cross Blood Transfusion Service of Upper Austria, Linz, Austria.,Austrian Cluster for Tissue Regeneration
| | - H Redl
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, AUVA Research Centre, Linz, Vienna, Austria.,Austrian Cluster for Tissue Regeneration
| | - M van Griensven
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, AUVA Research Centre, Linz, Vienna, Austria.,Austrian Cluster for Tissue Regeneration
| | - C Gabriel
- Red Cross Blood Transfusion Service of Upper Austria, Linz, Austria.,Austrian Cluster for Tissue Regeneration
| | - A Peterbauer-Scherb
- Red Cross Blood Transfusion Service of Upper Austria, Linz, Austria.,Austrian Cluster for Tissue Regeneration
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Stabentheiner S, Danzer M, Niklas N, Atzmüller S, Pröll J, Hackl C, Polin H, Hofer K, Gabriel C. Overcoming methodical limits of standard RHD genotyping by next-generation sequencing. Vox Sang 2010; 100:381-8. [PMID: 21133932 DOI: 10.1111/j.1423-0410.2010.01444.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND AND OBJECTIVES Molecular variations of the RHD gene may result in the reduced expression of the D antigen and altered Rh phenotypes. In many occasions, they cannot be typed reliably by standard serological methods. Sequence-based typing is the gold standard to determine rare and unknown RHD genotypes. For this pilot study, sequence-based typing by standard Sanger sequencing was compared to a newly established next-generation sequencing approach based on pyrosequencing. MATERIALS AND METHODS Twenty-six DNA samples were selected after primary serological testing exhibiting a weak reaction in Rh phenotype. Parallel sequence analysis of the complete coding sequence including adjacent intronic sequences allowed a comparison of the methodical potency in mutation detection of Sanger with next-generation sequencing. RESULTS Sanger sequencing revealed 39 RHD polymorphisms in 21 of 26 samples in the RHD coding region, while pyrosequencing detected all but two alterations resulting in a concordance rate of 94·9% and clearly revealed a heterozygous compound mutation in one sample with RHDψ and Weak D type 4 alleles. The resolution of cis/trans linkage of polymorphisms and exact characterization of a 37 bp duplication was achieved by next-generation sequencing. CONCLUSION Our data suggest that next-generation sequencing offers a new development for high-throughput and clonal sequencing for molecular RHD genotyping. However, further attempts in the methodical set-up have to be undertaken prior to validation and introduction as a routine service.
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Affiliation(s)
- S Stabentheiner
- Red Cross Transfusion Service for Upper Austria, Krankenhausstrasse 7, Linz, Austria.
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Stadler G, Hennerbichler S, Lindenmair A, Peterbauer A, Hofer K, van Griensven M, Gabriel C, Redl H, Wolbank S. Phenotypic shift of human amniotic epithelial cells in culture is associated with reduced osteogenic differentiation in vitro. Cytotherapy 2009; 10:743-52. [PMID: 18985480 DOI: 10.1080/14653240802345804] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
BACKGROUND Amniotic membrane is a highly promising cell source for tissue engineering. Being part of the placenta, this tissue is abundantly available. It can be processed easily to yield large amounts of epithelial and mesenchymal cells that have shown broad differentiation potential. For tissue-engineering purposes, cells may be applied either directly after isolation from the tissue or after a period of in vitro expansion to obtain higher cell numbers. In order to investigate the advantages and drawbacks of these strategies we compared freshly isolated and cultivated human amniotic epithelial cells (hAEC) regarding their surface antigen (Ag) expression profile and osteogenic differentiation capacity. METHODS Expression of surface Ag that are characteristic for mesenchymal stromal and embryonic stem cells was analyzed by flow cytometry. Different protocols for osteogenic and adipogenic differentiation were compared. RESULTS We have demonstrated that expression of surface Ag changes dramatically during cultivation of hAEC. While not or only weakly expressed on primary isolates, the mesenchymal markers CD13, CD44, CD49e, CD54, CD90 and CD105 are strongly up-regulated during in vitro propagation. In contrast, expression of the embryonic markers TRA-1-60 and TRA-1-81, but not SSEA-4, rapidly decreases upon cultivation. This phenotypic shift is associated with a reduction in osteogenic differentiation. DISCUSSION Our results suggest that phenotypic alterations of hAEC during in vitro cultivation might be responsible for a functional reduction of the differentiation potential, which has to be considered for the potential application of these cells in regenerative medicine.
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Affiliation(s)
- G Stadler
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology/AUVA Research Center, Linz/Vienna, Austria
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Abstract
We report here the novel human leukocyte antigens (HLA)-Cw*0429 and HLA-DRB3*0223 alleles identified during routine cord blood characterisation by sequence-based typing.
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Affiliation(s)
- M Danzer
- Red Cross Transfusion Service of Upper Austria, Linz, Austria.
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10
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Polin H, Danzer M, Prll J, Hofer K, Heilinger U, Zopf A, Gabriel C. Introduction of a real-time based blood group genotyping approach. Vox Sang 2008; 95:125-30. [DOI: 10.1111/j.1423-0410.2008.01067.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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11
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Abstract
The new allele HLA-A*1129 showed one nucleotide difference form A*110101 at codon 172 (CTG>CAG).
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Affiliation(s)
- M Danzer
- Red Cross Transfusion Service of Upper Austria, Linz, Austria.
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13
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14
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Cheung B, Heskin R, Hofer K, Gagnon M. The menstrual cycle and susceptibility to coriolis-induced sickness. J Vestib Res 2002; 11:129-36. [PMID: 11847456] [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: 02/23/2023]
Abstract
Survey studies on motion sickness susceptibility suggest that females tend to report greater severity in illness and higher incidence of vomiting than males. Menstruation is said to be a contributing factor. A recent study suggested that females were least susceptible to seasickness during ovulation in a "round the world" yacht race. Sixteen subjects (18-36 years old) were exposed to Coriolis cross-coupling stimulation in the laboratory. They were tested once during permenstruation (Day 1-5), ovulation (Day 12-15) and premenstruation (Day 24-28), based on a normalized 28-day cycle, in a randomised design. Physiological measurements of motion sickness included forearm and calf cutaneous blood flow. Subjective evaluation of sickness symptoms was based on Graybiel's diagnostic criteria and Golding's rating method. Our results indicated that under controlled laboratory conditions, different phases of the menstrual cycle appear to have no influence on subjective symptoms of motion sickness or on cutaneous blood flow increase in the forearm and calf. The lack of commonality between the types and levels of hormones that are released during motion sickness and those that are involved in different menstrual phases appears to support our findings.
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Affiliation(s)
- B Cheung
- Aerospace Life Support Section, Defence and Civil Institute of Environmental Medicine, 1133 Sheppard Ave. W, Toronto, Ontario, Canada.
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15
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Abstract
Using venous occlusion plethysmography, Sunahara et al. reported that Coriolis-induced nausea was accompanied by an increase in forearm blood flow, suggesting a decrease in sympathetic activity to this vascular bed. No significant blood pressure and heart rate changes were observed. Vasodilation of the limbs theoretically impairs orthostatic tolerance, particularly if blood flow is shown to increase simultaneously in the lower limbs. This study examined the latter possibility. Seventeen subjects were exposed to the Coriolis cross-coupling effects induced by 20 RPM yaw rotation, and a simultaneous 45 degrees pitch forward head movement in the sagittal plane every 12 s. Forearm and calf skin blood flow were monitored in real-time using laser Doppler flowmetry (PeriFlux 4001). Our results indicated a significant (p < 0.001) simultaneous forearm and calf skin blood flow increase as a result of Coriolis cross-coupling across all 15 susceptible subjects. No significant changes in blood pressure and heart rate were observed. Coriolis-induced cardiovascular changes may confound previous reports on reduced G tolerance using ground-based centrifuges that invariably evoke cross-coupling effects.
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Affiliation(s)
- B Cheung
- Defence and Civil Institute of Environmental Medicine, Toronto, ON, Canada.
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16
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Cheung B, Askari V, Hofer K, Goodman L. Roll vs. pitch rotation. Aviat Space Environ Med 2000; 71:1262. [PMID: 11439729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
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17
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Cheung B, Hofer K, Brooks CJ, Gibbs P. Underwater disorientation as induced by two helicopter ditching devices. Aviat Space Environ Med 2000; 71:879-88. [PMID: 11001339] [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: 02/17/2023]
Abstract
BACKGROUND Spatial orientation is based on the integration of concordant and redundant information from the visual, vestibular, and somatosensory systems. When a person is submerged underwater, somatosensory cues are reduced, and vestibular cues are ambiguous with respect to upright or inverted position. Visual cues may be lost as a result of reduced ambient light. Underwater disorientation has been cited as one of the major factors that could inhibit emergency egress after a helicopter ditching into water. One countermeasure to familiarize aircrew with underwater disorientation is emergency egress training. This study examined the relative degree of underwater disorientation induced by the Modular Egress Training Simulator (METS) and the Shallow Water Egress Trainer (SWET). METHODS There were 36 healthy subjects (28 males and 8 females) who participated in the study. Underwater disorientation was quantified by measuring the deviation of subjective vertical-pointing from the gravitational vertical, time to egress, and subjective reports of disorientation and ease of egress. A repeated measure design was employed with seat position (SWET chair, METS window, and METS aisle) as the sole factor. RESULTS Subjective response data indicated that the degree of disorientation is rated significantly higher, and the ease of egress is rated worse from the two METS seat positions than from the SWET. This is supported by the findings that subjective vertical-pointing accuracy is worse in the METS seat positions than in the SWET (p < 0.01). The time to egress is longer from the two METS seat positions than from SWET (p < 0.01). CONCLUSION Our results indicate that the METS device is effective for inducing underwater disorientation as provoked by simulated helicopter ditching. disorientation, vestibular, subjective pointing.
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Affiliation(s)
- B Cheung
- Defense and Civil Institute of Environmental Medicine, Toronto, Ontario, Canada.
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19
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Abstract
The cognitive-energetical approach, which relies on the discrete stage model of additive factors logic, asserts that basal energetical mechanisms such as arousal act via particular information processing stages. The anaesthetic gas nitrous oxide (N(2)O) produces additivity at four of the five perceptual and central stages, but its effect on the remaining stage, feature extraction, is unknown. We investigated this stage using 12 subjects who performed a visual oddball experiment in which two levels of stimulus quality, three levels of breathing mixture (air, 25% and N(2)O, 35%) and three levels of stimulus probability were combined factorially. Reaction time (RT) and P300 were collected simultaneously. The RT results showed additivity between N(2)O, stimulus quality and probability. P300 latency also showed additivity between N(2)O and stimulus quality. Since the discrete stage model cannot easily account for the exhaustive additivity displayed by N(2)O on perceptual and central stages, we performed a continuous cascade model simulation to determine whether it is better able to account for this phenomenon. We found that exhaustive additivity could be reproduced by adding a time delay to the activation rate of the first stage, which we interpreted as evidence that N(2)O causes slowing prior to stage processing. To account for these results, we propose a two-tiered energetical model in which a lower GABAergic reticular system (influenced by N(2)O) modulates the activity of upper 'arousal-like' multidimensional ascending thalamocortical systems. The applicability of this model to drugs such as the barbiturates, the benzodiazepines and ethanol, as well as the aging process, is discussed.
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Affiliation(s)
- B Fowler
- Department of Kinesiology and Health Science, 353 Bethune College, York University, 4700 Keele Street, North York, Canada.
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20
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Cheung B, Hofer K, Goodman L. The effects of roll vs. pitch rotation in humans under orthostatic stress. Aviat Space Environ Med 1999; 70:966-74. [PMID: 10519474] [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: 02/14/2023]
Abstract
BACKGROUND It has been known since 1953 that pre-exposure to less than +1 Gz will reduce subsequent +Gz-tolerance. With few exceptions, during operational flying, the transition from hypogravity to hypergravity involves roll as well as pitch rotation. We examined the effect of roll vs. pitch rotation while undergoing transition from hypogravity to +1 Gz on a tilt table. METHODS Twelve subjects (28-47 yr old) were rotated at 45 degrees x s(-1) from head-up (HU) at 15 degrees relative to gravitational vertical to 135 degrees head-down (HD) and back to the HU position after different HD dwell times. HD dwell times were set at 7, 15, and 30 s. The subject was rotated about the interaural axis (pitch) and about the naso-occipital axis (roll). Both the HD dwell times and axes of rotation were randomized within and across subjects. BP and heart rate were recorded during the HU-HD-HU maneuver. RESULTS Analysis of variance, repeated measure design revealed that the rate and magnitude of BP decrease induced by the HD to HU maneuver is significantly higher (p < 0.01) in roll than in pitch during all HD dwell times. The decrease of BP at 7s is significantly (p < 0.01) higher than at 15s and 30s. Heart rate increases significantly higher (p < 0.01) in pitch than in roll at 7s-dwell time. CONCLUSION Our results suggest that the compensatory mechanism to orthostatic stress is more efficient in response to pitch than roll rotation. This is reflected from the findings that the mean magnitude of OH (orthostatic hypotension) and the rate of BP decrease induced by the HD-HU maneuver is significantly greater in roll rotation than pitch rotation. The mean HR increase post HD-HU rotation is significantly higher in the pitch than the roll rotation. The significant rate of BP decrease during HD-HU roll rotation could have important implications for maintaining G-tolerance and spatial orientation during subsequent exposure to hypergravity.
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Affiliation(s)
- B Cheung
- Defence and Civil Institute of Environmental Medicine, Toronto, Ont., Canada.
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21
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Cheung B, Hofer K. Degradation of visual pursuit during sustained +3 Gz acceleration. Aviat Space Environ Med 1999; 70:451-8. [PMID: 10332939] [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: 02/12/2023]
Abstract
BACKGROUND During positive acceleration, there is a diminished flow of blood to all regions above the heart. This is manifested by the commonly described loss of peripheral vision, greyout and blackout, which have been investigated extensively. The ability to select appropriate scanning patterns and to efficiently process visual information is one of the important determinants of scan effectiveness. This study investigates the performance of the smooth pursuit system under sustained +3 Gz before any signs of loss of vision. METHODS Eleven subjects with no known oculomotor and vestibular anomalies participated in the study. Horizontal and vertical pursuit at amplitudes of 10 and 20 degrees were investigated in each of the subjects over 4 separate days. During each test session, pursuit targets of a predictable sine wave, oscillating at 0.2, 0.4, 0.8, 1.2 and 1.6 Hz were presented to the subjects in a random order. Horizontal and vertical eye movements were recorded using the El-Mar eye tracking system. The subjects were tested in 4 trials: 1) at 1 G before exposure to increased acceleration; 2) during sustained +3 Gz; 3) immediately after the +3 Gz exposure; and 4) 5 min after the +3 Gz exposure. RESULTS Breakdown in smooth pursuit in response to horizontal and vertical sinusoidal stimuli during +3 Gz is indicated by a statistically significant decrease in gain and an increase in phase lag (p < 0.01). This is most obvious when the stimulus frequency is greater than 0.4 Hz. Qualitatively, the pursuit response during acceleration was ataxic and disorganized in appearance. CONCLUSION It is postulated that degradation of pursuit gain and phase could be due to central hypoxia, and that the increase of G loading on the vestibular system could affect the neural integration of the pursuit signal in the vestibular nuclei with its direct output to the oculomotor system.
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Affiliation(s)
- B Cheung
- Defence and Civil Institute of Environmental Medicine, Toronto, Ont., Canada
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23
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Hofer K, Johari GP. Effect of ions on intermolecular association and sub‐Tg dielectric relaxation in isomeric octanols. J Chem Phys 1991. [DOI: 10.1063/1.461000] [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: 11/14/2022] Open
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Gieren A, Brüggeller P, Hofer K, Hübner T, Ruiz-Pérez C. Hydrido{tris[2-(diphenylphosphino)ethyl]phosphino-P,P',P'',P'''}platin(II) tetraphenylborat. Acta Crystallogr C 1989. [DOI: 10.1107/s010827018801073x] [Citation(s) in RCA: 3] [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: 11/11/2022] Open
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Hofer K. Dr. Lucy Hobbs Taylor, first woman dentist. CAL 1981; 45:13-5, 18. [PMID: 7028217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Hofer K. Try Hippocrates' home made tooth powder. CAL 1978; 42:27-8. [PMID: 380787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Hofer K. President's message: attributes of profession and barriers to obtaining professional status. Med Rec News 1978; 49:4. [PMID: 10238852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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Hofer K. Issues related to RRA and ART roles and responsibilities. Med Rec News 1978; 49:4. [PMID: 10307019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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Hofer K. [Climate comfort and health resort]. Wien Med Wochenschr 1967; 117:444-6. [PMID: 5300694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Hofer K. [The influence of the preparation stimulus on the ultraviolet ray resistance of the outer epidermis of Allium cepa]. Protoplasma 1966; 61:1-11. [PMID: 5920038 DOI: 10.1007/bf01247909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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