Calixto Machado

Prof. Calixto Machado

Institutte of Neurology and Neurosurgery, Havana, La Habana, Cuba
orcid

Research Focus & Metrics

Academic Career Length

24Years (2003-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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19 September 2013 in Journal of Autism and Developmental Disorders
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Journal Article
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CMCalixto Machado
Calixto Machado
MEMario Estévez
Mario Estévez
Gerry LeismanGerry Leisman
Gerry Leisman
RMRobert Melillo
Robert Melillo
RRRafael Rodríguez
Rafael Rodríguez
CBCarlos Beltrán
Carlos Beltrán
We studied autistics by quantitative EEG spectral and coherence analysis during three experimental conditions: basal, watching a cartoon with audio (V–A), and with muted audio band (VwA). Significant reductions were found for the absolute power spectral density (PSD) in the central region for delta and theta, and in the posterior region for sigma and beta bands, lateralized to the right hemisphere. When comparing VwA versus the V–A in the midline regions, we found significant decrements of absolute PSD for delta, theta and alpha, and increments for the beta and gamma bands. In autistics, VwA versus V–A tended to show lower coherence values in the right hemisphere. An impairment of visual and auditory sensory integration in autistics might explain our results.

30 March 2007 in Journal of Medical Ethics
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CMCalixto Machado
Calixto Machado
JKJulius Kerein
Julius Kerein
YFYazmina Ferrer
Yazmina Ferrer
LPLiana Portela
Liana Portela
MGMaria de la C García
Maria de la C García
Jose Maria ManeroJose Maria Manero
Jose Maria Manero
Although it is commonly believed that the concept of brain death (BD) was developed to benefit organ transplants, it evolved independently. Transplantation owed its development to advances in surgery and immunosuppressive treatment; BD owed its origin to the development of intensive care. The first autotransplant was achieved in the early 1900s, when studies of increased intracranial pressure causing respiratory arrest with preserved heartbeat were reported. Between 1902 and 1950, the BD concept was supported by the discovery of EEG, Crile’s definition of death, the use of EEG to demonstrate abolition of brain potentials after ischaemia, and Crafoord’s statement that death was due to cessation of blood flow. Transplantation saw the first xenotransplant in humans and the first unsuccessful kidney transplant from a cadaver. In the 1950s, circulatory arrest in coma was identified by angiography, and the death of the nervous system and coma dépassé were described. Murray performed the first successful kidney transplant. In the 1960s, the BD concept and organ transplants were instantly linked when the first kidney transplant using a brain-dead donor was performed; Schwab proposed to use EEG in BD; the Harvard Committee report and the Sydney Declaration appeared; the first successful kidney, lung and pancreas transplants using cadaveric (not brain-dead) donors were achieved; Barnard performed the first human heart transplant. This historical review demonstrates that the BD concept and organ transplantation arose separately and advanced in parallel, and only began to progress together in the late 1960s. Therefore, the BD concept did not evolve to benefit transplantation.

1 July 2004 in Clinical Eeg and Neuroscience
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CMCalixto Machado
Calixto Machado
ECElena Cuspineda
Elena Cuspineda
PVPedro Valdés
Pedro Valdés
TVTrinidad Virues
Trinidad Virues
FLFrancis Liopis
Francis Liopis
YAYoel Avila
Yoel Avila
This paper focuses on the application of quantitative electric tomography (qEEGT) to map changes in EEG generators for detection of early signs of ischemia in patients with acute middle cerebral artery stroke.Thirty-two patients were studied with the diagnosis of acute ischemic stroke of the left middle cerebral artery territory, within the first 24 hours of their clinical evolution. Variable Resolution Electrical Tomography was used for estimating EEG source generators. High resolution source Z-spectra and 3- dimensional images of Z values for all the sources at each frequency were obtained for all cases. To estimate statistically significant increments and decrements of brain electric activity within the frequency spectra, the t-Student vs. Zero test was performed.A significant increment of delta activity was observed on the affected vascular territory, and a more extensive increment of theta activity was detected. A significant alpha decrement was found in the parieto-occipital region of the affected cerebral hemisphere (left), and in the medial and posterior region of the right hemisphere.These findings suggest that qEEGT Z delta images are probably related to the main ischemic core within the affected arterial territory; penumbra, diaschisis, edema, might explain those observed theta and alpha abnormalities. It was concluded that qEEGT is useful for the detection of early signs of ischemia in acute ischemic stroke.

14 June 2005 in Neurology
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CMCalixto Machado
Calixto Machado
In 1968, publication of the Harvard committee’s report concerning “irreversible coma” established a paradigm for defining death by neurologic criteria (brain death [BD]). Five years earlier, Dr. Guy Alexandre, a Belgian surgeon, had not only adopted closely similar diagnostic criteria for BD but also applied those criteria in performing the first organ transplant from a brain-dead donor—a procedure many of his colleagues considered ethically unacceptable. To put those events into present-day perspective, the author reviewed the proceedings of a Ciba Symposium held in London in 1966 at which Alexandre introduced his pioneering view, obtaining information and documents from Alexandre and others who attended that meeting. Comparing Alexandre’s approach with the Harvard report and later advances helps in understanding how both defining death by brain criteria and transplanting organs from a brain-dead donor have become morally tolerable today.

25 February 2010 in Neurology International
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CMCalixto Machado
Calixto Machado
Brain death (BD) should be understood as the ultimate clinical expression of a brain catastrophe characterized by a complete and irreversible neurological stoppage, recognized by irreversible coma, absent brainstem reflexes, and apnea. The most common pattern is manifested by an elevation of intracranial pressure to a point beyond the mean arterial pressure, and hence cerebral perfusion pressure falls and, as a result, no net cerebral blood flow is present, in due course leading to permanent cytotoxic injury of the intracranial neuronal tissue. A second mechanism is an intrinsic injury affecting the nervous tissue at a cellular level which, if extensive and unremitting, can also lead to BD. We review here the methodology of diagnosing death, based on finding any of the signs of death. The irreversible loss of cardio-circulatory and respiratory functions can cause death only when ischemia and anoxia are prolonged enough to produce an irreversible destruction of the brain. The sign of such loss of brain functions, that is to say BD diagnosis, is fully reviewed.

30 November 2007 in Journal of Medical Ethics
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Journal Article
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CMCalixto Machado
Calixto Machado
JKJ Korein
J Korein
YFY Ferrer
Y Ferrer
LPL Portela
L Portela
MGM de la C García
M de la C García
Jose Maria ManeroJose Maria Manero
Jose Maria Manero
On 5 August 1968, publication of the Harvard Committee’s report on the subject of “irreversible coma” established a standard for diagnosing death on neurological grounds. On the same day, the 22nd World Medical Assembly met in Sydney, Australia, and announced the Declaration of Sydney, a pronouncement on death, which is less often quoted because it was overshadowed by the impact of the Harvard Report. To put those events into present-day perspective, the authors reviewed all papers published on this subject and the World Medical Association web page and documents, and corresponded with Dr A G Romualdez, the son of Dr A Z Romualdez. There was vast neurological expertise among some of the Harvard Committee members, leading to a comprehensible and practical clinical description of the brain death syndrome and the way to diagnose it. This landmark account had a global medical and social impact on the issue of human death, which simultaneously lessened reception of the Declaration of Sydney. Nonetheless, the Declaration of Sydney faced the main conceptual and philosophical issues on human death in a bold and forthright manner. This statement differentiated the meaning of death at the cellular and tissue levels from the death of the person. This was a pioneering view on the discussion of human death, published as early as in 1968, that should be recognised by current and future generations.