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Savc M, Glaser V, Holobar A. On the Impact of Muscle Shortening on Non-Negative Matrix Factorization of Dynamic Surface Electromyograms. Annu Int Conf IEEE Eng Med Biol Soc 2018; 2018:5970-5973. [PMID: 30441696 DOI: 10.1109/embc.2018.8513670] [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: 11/10/2022]
Abstract
We analyzed the sensitivity of Non-negative Matrix Factorization (NMF) of dynamic surface electromyograms (EMG) to muscle shortening. We first identified Motor unit action potentials (MUAPs) by decomposing experimentally recorded EMG signals during slow shortening of biceps brachii muscle in five young healthy males. We then used these MUAPs to generate different synthetic EMG signals with different muscle shortening and excitation profiles. Afterwards, we applied NMF to the synthetic EMG signals and calculated Pearson correlation coefficient (CC) between the extracted NMF components and a) muscle shortening and b) muscle excitation profiles. The results demonstrated good match between NMF components and muscle excitation profiles, but only when the muscle excitation level changed for at least 10 % during the muscle shortening. During constant muscle excitation, the resulting NMF components correlated significantly with the muscle shortening profiles. These results demonstrate that NMF components reflect not only the muscle excitation profiles but also muscle shortening profiles. Therefore, the results of NMF analysis of dynamic EMG signals need to be interpreted with caution.
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Glaser V, Farina D, Holobar A. Simulations of high-density surface electromyograms in dynamic muscle contractions. Annu Int Conf IEEE Eng Med Biol Soc 2018; 2017:3453-3456. [PMID: 29060640 DOI: 10.1109/embc.2017.8037599] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We describe the extension of pre-existing cylindrical volume conductor model to synthetic high-density surface electromyograms (hdEMG), simulated during dynamic contractions of fusiform skeletal muscles. Its modular structure comprises two main parts. First, dynamic changes of motor unit action potentials (MUAPs) during 36 discrete steps of muscle shortening are simulated. Second, the increase in depth of simulated motor units (MUs) due to shortening and thickening of muscle fibers is simulated. MU firing patterns are generated with the model proposed by Fuglevand et al. and convolved with simulated MUAPs. In this way, the hdEMG simulator can be used to generate dynamic hdEMG of arbitrary muscle shortening, thickening and excitation profiles. In order to demonstrate the value of the aforementioned simulator we independently analyze the impact of muscle shortening and muscle thickening on MU identification by Convolution Kernel Compensation (CKC) technique.
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Glaser V, Holobar A. On the impact of spike segmentation on motor unit identification in dynamic surface electromyograms. Annu Int Conf IEEE Eng Med Biol Soc 2017; 2017:430-433. [PMID: 29059902 DOI: 10.1109/embc.2017.8036854] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We discuss the adaptation of preexisting Convolution Kernel Compensation (CKC) surface electromyogram (EMG) decomposition technique to dynamic muscle contractions. In particular, three different algorithms for segmentation of motor unit (MU) spike trains into MU firings are discussed and mutually compared on synthetic dynamic surface EMG. The first segmentation algorithm employs a priori knowledge of the regularity of MU firings. The second one builds on K-means classification of MU spikes, whereas the third one combines both the regularity of MU firings and the previously introduced Pulse-to-Noise Ratio (PNR). On average, 5.5 ± 0.6 MUs were identified with sensitivity of 88.4 % ± 17.0 %, 83.8 % ± 16.7 % and 90.7 % ± 15.1 % for the first, the second and the third segmentation algorithm, respectively, demonstrating the feasibility of MU identification in moderate dynamic muscle contractions. In our tests, the third segmentation approach demonstrated superior accuracy in MU identification.
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Aguiar A, Moreira E, Hoeller A, Oliveira P, Córdova F, Glaser V, Walz R, Cunha R, Leal R, Latini A, Prediger R. Exercise attenuates levodopa-induced dyskinesia in 6-hydroxydopamine-lesioned mice. Neuroscience 2013; 243:46-53. [DOI: 10.1016/j.neuroscience.2013.03.039] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 03/02/2013] [Accepted: 03/23/2013] [Indexed: 11/15/2022]
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Holobar A, Glaser V, Gallego JA, Dideriksen JL, Farina D. Non-invasive characterization of motor unit behaviour in pathological tremor. J Neural Eng 2012; 9:056011. [PMID: 22962251 DOI: 10.1088/1741-2560/9/5/056011] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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de Oliveira J, Hort MA, Moreira ELG, Glaser V, Ribeiro-do-Valle RM, Prediger RD, Farina M, Latini A, de Bem AF. Positive correlation between elevated plasma cholesterol levels and cognitive impairments in LDL receptor knockout mice: relevance of cortico-cerebral mitochondrial dysfunction and oxidative stress. Neuroscience 2011; 197:99-106. [PMID: 21945034 DOI: 10.1016/j.neuroscience.2011.09.009] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Revised: 08/23/2011] [Accepted: 09/05/2011] [Indexed: 11/30/2022]
Abstract
Convergent epidemiological, clinical, and experimental findings indicate that hypercholesterolemia contributes to the onset of Alzheimer's disease (AD)-like dementia, but the exact underlying mechanisms remains unknown. In this study, we evaluated the cognitive performance of mice submitted to a model of hypercholesterolemia, as well as its relationship with mitochondrial dysfunction and oxidative stress, two key events involved in AD pathogenesis. Wild-type C57bl/6 or low density lipoprotein receptor (LDLr)-deficient mice were fed with either standard or cholesterol-enriched diet for a 4-week period and tested for spatial learning and memory in the object location task. LDLr⁻/⁻ mice displayed spatial learning and memory impairments regardless of diet. Moreover, LDLr⁻/⁻ mice fed cholesterol-enriched diet presented a significant decrease in the mitochondrial complexes I and II activities in the cerebral cortex, which were negatively correlated with respective blood cholesterol levels. Additionally, hypercholesterolemic LDLr⁻/⁻ mice presented a significant decrease in glutathione levels, about 40% increase in the thiobarbituric acid-reactive substances levels, as well as an imbalance between the peroxide-removing-related enzymes glutathione peroxidase/glutathione reductase activities in the cerebral cortex. These findings indicate a significant relationship between hypercholesterolemia, cognitive impairment, and cortico-cerebral mitochondrial dysfunctional/oxidative stress. Because of the involvement of such alterations in AD patients, our data render this mouse model of hypercholesterolemia a useful approach to comprehend the molecular events mediating AD pathogenesis.
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Affiliation(s)
- J de Oliveira
- Departamento de Bioquímica, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC, Brazil
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Sigwalt AR, Budde H, Helmich I, Glaser V, Ghisoni K, Lanza S, Cadore EL, Lhullier FLR, de Bem AF, Hohl A, de Matos FJ, de Oliveira PA, Prediger RD, Guglielmo LGA, Latini A. Molecular aspects involved in swimming exercise training reducing anhedonia in a rat model of depression. Neuroscience 2011; 192:661-74. [PMID: 21712072 DOI: 10.1016/j.neuroscience.2011.05.075] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Revised: 04/19/2011] [Accepted: 05/28/2011] [Indexed: 12/19/2022]
Abstract
Patients suffering from depression frequently display hyperactivity of the hypothalamic-pituitary-adrenal axis (HPA) resulting in elevated cortisol levels. One main symptom of this condition is anhedonia. There is evidence that exercise training can be used as a rehabilitative intervention in the treatment of depressive disorders. In this scenario, the aim of the present study was to assess the effect of an aerobic exercise training protocol on the depressive-like behavior, anhedonia, induced by repeated dexamethasone administration. The study was carried out on adult male Wistar rats randomly divided into four groups: the "control group" (C), "exercise group" (E), "dexamethasone group" (D) and the "dexamethasone plus exercise group" (DE). The exercise training consisted of swimming (1 h/d, 5 d/wk) for 3 weeks, with an overload of 5% of the rat body weight. Every day rats were injected with either dexamethasone (D/DE) or saline solution (C/E). Proper positive controls, using fluoxetine, were run in parallel. Decreased blood corticosterone levels, reduced adrenal cholesterol synthesis and adrenal weight (HPA disruption), reduced preference for sucrose consumption and increased immobility time (depressive-like behavior), marked hippocampal DNA oxidation, increased IL-10 and total brain-derived neurotrophic factor (BDNF; pro-plus mature-forms) and a severe loss of body mass characterized the dexamethasone-treated animals. Besides increasing testosterone blood concentrations, the swim training protected depressive rats from the anhedonic state, following the same profile as fluoxetine, and also from the dexamethasone-induced impaired neurochemistry. The data indicate that physical exercise could be a useful tool in preventing and treating depressive disorders.
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Affiliation(s)
- A R Sigwalt
- Laboratório de Bioenergética e Estresse Oxidativo, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Brazil
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Holobar A, Glaser V, Gallego JA, Dideriksen JL, Farina D. Noninvasive analysis of motor unit behavior in pathological tremor. Annu Int Conf IEEE Eng Med Biol Soc 2011; 2011:7512-7515. [PMID: 22256076 DOI: 10.1109/iembs.2011.6091852] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A robust surface EMG decomposition tool, referred to as tremor-optimized Convolution Kernel Compensation (CKC) technique, is described. This technique modifies and extends the previously published CKC method in order to circumvent the typical assumption on regularity and asynchrony of motor unit firings in normal condition and adapt to the discharge patterns in pathological tremor. The results on synthetic and experimental surface EMG signals demonstrate high performance of decomposition. In the case of simulated surface EMG with 20 dB SNR, excitation level of 20% maximum voluntary contraction (MVC) and simulated tremor frequency of 8 Hz, the newly proposed method identified 8 ± 2 motor units with sensitivity of motor unit discharge identification ≥ 95 % and false alarm and miss rates ≤ 5%. The performance worsened with increasing noise power, with 5 ± 2 motor units identified at 10 dB SNR and 3 ± 1 at 0 dB SNR. In 24 recordings of high-density surface EMG signals from four tremor-affected patients, the modified CKC technique identified 134 motor units (6 ± 4 motor units per contraction).
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Affiliation(s)
- A Holobar
- Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia.
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Glaser V, Boni A, Albuquerque C. Ocorrência de Hepatozoon spp. (Apicomplexa, Hepatozoidae) em serpentes do gênero Bothrops de cativeiro. ARQ BRAS MED VET ZOO 2008. [DOI: 10.1590/s0102-09352008000500040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Glaser V. Competition between flu drugs feverishly anticipated. Nat Biotechnol 1999; 17:1059. [PMID: 10545904 DOI: 10.1038/15041] [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: 11/08/2022]
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Glaser V. Sugen's strategy: a signal for P&U purchase. Nat Biotechnol 1999; 17:745-6. [PMID: 10429230 DOI: 10.1038/11670] [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: 11/09/2022]
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Glaser V. Neuraminidase inhibitors take bite out of influenza. Nat Biotechnol 1998; 16:1002. [PMID: 9831018 DOI: 10.1038/3443] [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: 11/09/2022]
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Glaser V. Anti-inflammatory inflames Centocor's profits. Nat Biotechnol 1998; 16:900. [PMID: 9788334 DOI: 10.1038/nbt1098-900] [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: 11/09/2022]
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Glaser V. PE/TIGR provokes genome sequencing skeptics. Nat Biotechnol 1998; 16:610-1. [PMID: 9661182 DOI: 10.1038/nbt0798-610a] [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: 02/08/2023]
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Glaser V. Biotech unruffled by setbacks. Nat Biotechnol 1997; 15:610-1. [PMID: 9219254 DOI: 10.1038/nbt0797-610] [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: 02/04/2023]
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Zinchenko V, Babykin M, Glaser V, Mekhedov S, Shestakov S. Mutation in ntrC gene leading to the derepression of nitrogenase synthesis in Rhodobacter sphaeroides. FEMS Microbiol Lett 1997; 147:57-61. [PMID: 9037764 DOI: 10.1111/j.1574-6968.1997.tb10220.x] [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] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The Rhodobacter sphaeroides mutants Drn12 and Drn21 derepressed for nitrogenase synthesis in the presence of ammonia and impaired in utilization of certain nitrogen sources have been analyzed. Both mutants show a low level of expression of the glnBA operon. The DNA fragment restoring the wild-type phenotype to these mutants contains the 3'-portion of ntrB gene and the entire ntrC gene. Sequence analysis showed that Drn12 bears a missense mutation in the ntrC gene. The mutation results in the replacement of a glycine residue by aspartate within the N-terminal domain of the NtrC protein. Pleiotropic phenotypes of Drn12 and Drn21 appear to be associated with an alteration in the regulation of glnBA expression.
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Affiliation(s)
- V Zinchenko
- Department of Genetics, Moscow State University, Russia.
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Glaser V. "Ganske" threatens biotechnology patents worldwide. Nat Biotechnol 1997; 15:121. [PMID: 9035128 DOI: 10.1038/nbt0297-121a] [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: 02/03/2023]
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Glaser V. Berlex continues legal challenge to FDA over MS drug. Nat Biotechnol 1996; 14:811-2. [PMID: 9630997 DOI: 10.1038/nbt0796-811b] [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: 02/07/2023]
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Glaser V. Progenics, Somatix in phase III cancer vaccine trials. Nat Biotechnol 1996; 14:257, 260. [PMID: 9630880 DOI: 10.1038/nbt0396-257] [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: 02/07/2023]
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Glaser V. Consensus on future directions in Parkinson's disease research. Mol Med Today 1995; 1:350. [PMID: 9445759 DOI: 10.1016/s1357-4310(95)93587-8] [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] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Glaser V. Pharmacia challenges Genentech in rhGH market. Biotechnology (N Y) 1995; 13:1038, 1040. [PMID: 9678910 DOI: 10.1038/nbt1095-1038] [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] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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Glaser V. Soluble CD4: a new antiviral treatment for AIDS. N Y State J Med 1990; 90:280-1. [PMID: 2348952] [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: 12/31/2022]
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Glaser V. Metaproterenol inhaler taken off market. N Y State J Med 1990; 90:46. [PMID: 2296400] [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: 12/31/2022]
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Glaser V. Promoting bicycle helmet use in children. N Y State J Med 1990; 90:47. [PMID: 2296403] [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: 12/31/2022]
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Glaser V. Too many surgeons for too few operations? N Y State J Med 1990; 90:47. [PMID: 2296404] [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: 12/31/2022]
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Glaser V. Risk factors for teenage suicide. N Y State J Med 1990; 90:46. [PMID: 2296401] [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: 12/31/2022]
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Glaser V. Lung cancer rates decreasing for young people in US. N Y State J Med 1990; 90:46-7. [PMID: 2296402] [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: 12/31/2022]
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Glaser V. AIDS antibodies may enhance viral infection. N Y State J Med 1988; 88:564. [PMID: 3231380] [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: 01/04/2023]
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Glaser V. Saliva shown to inhibit HIV-1 infectivity. N Y State J Med 1988; 88:452. [PMID: 3173835] [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: 01/04/2023]
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Glaser V. Study of polio vaccine's effects on AIDS faces roadblock. N Y State J Med 1988; 88:285. [PMID: 3380396] [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: 01/05/2023]
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Glaser V. The effect of zidovudine on antigen levels in HIV infection. N Y State J Med 1988; 88:284-5. [PMID: 3164101] [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: 01/04/2023]
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