Dr. Ngai

Research Labs:
Ngai Lab

• Research Overview
• Current Research
• Research Questions
• Research Methods
• Abstract
• Bibliography of Selected Publications

Research Overview

Alphonsus Ngai, PhD is a Research Assistant Professor of Neurological Surgery. His research focus is on cerebrovascular regulation. He has been a collaborator of Dr. Winn, Dr. Britz and now Dr. Sekhar and Dr. Kim. He is a collaborator on National Institutes of Health (NIH) grants, and a recipient of American Heart Association funding.

Current Research

1. Mechanisms that govern brain vessel function and blood flow, and how pathological states such as stroke may alter these mechanisms.
2. Developing experimental models for leptomeningeal vasoreactivity during focal stroke.
3. Determining the effect of certain stroke risk factors on impaired collateral flow and cerebrovascular reactivity.
4. Evaluating the efficacy of site and event –specific pharmacological agents that improve collateral flow and extend the time window for recanalization and other treatments.

Research Questions

1. How is cerebral blood flow regulated in health and in disease states, such as stroke?
2. How is brain blood flow coupled to neural activity in the brain?

Research Methods

• Laser Doppler Flowmetry
• Cranial window
• Cerebral artery occlusion (filament and embolic models)
• Laser speckle contrast imaging
• Infarct volume and behavioral deficit assessment.

Abstract

Collateral flow enhancement by pharmacological dilation of leptomeningeal collaterals improved outcome following middle cerebral artery occlusion. View the abstract.

Bibliography of Selected Publications

1. Ngai, A.C., K.R. Ko, S. Morii, and H.R. Winn. Effects of sciatic nerve stimulation on pial arterioles in rats. Am. J. Physiol. 254: H133-H139, 1988.
2. Ngai, A.C., and H.R. Winn. Modulation of cerebral arteriolar diameter by intraluminal flow and pressure. Circ. Res. 77: 832-840, 1995.
3. Ngai, A.C., M.A. Jolley, R. D’Ambrosio, J.R. Meno, and H.R. Winn. Frequency-dependent changes in cerebral blood flow and evoked potentials during somatosensory stimulation in the rat. Brain Research 837: 221-228, 1999.
4. Ngai, A.C., E.F. Coyne, and H.R. Winn. Receptor subtypes mediating adenosine-induced dilation of cerebral arterioles. Am. J. Physiol. Heart Circ. Physiol., Am J Physiol Heart Circ Physiol 280: H2329-H2335, 2001.
5. J.J. Iliff, R.D’Ambrosio, A.C. Ngai, and H.R. Winn. Adenosine receptors mediate glutamate-evoked arteriolar dilation in the rat cerebral cortex. Am. J. Physiol. Heart Circ. Physiol. 284: H1631-H1637, 2003.
6. Ngai, A.C., T.-S. Nguyen, J.R. Meno, and G.W. Britz. Postischemic augmentation of conducted dilation in cerebral arterioles. Stroke 38:124-130, 2007.
7. Britz G.W., J.R. Meno, I.-S. Park, T.J. Abel, A. Chowdhary, T.-S. Nguyen, H.R. Winn, and A.C. Ngai. Time-Dependent Alterations in Functional and Pharmacological Arteriolar Reactivity After Subarachnoid Hemorrhage. Stroke 38:1329-1335, 2007.
8. Park, I.-S., , J.R. Meno, C. Witt, T.K. Suttle, A. Chowdhary, T.-S. Nguyen, A.C. Ngai, and G.W. Britz. Subarachnoid hemorrhage model in the rat: modification of the endovascular filament model. J. Neurosci. Methods, 172:195-200, 2008.
9. Ngai, A.C., R.L. Mondares, Mayock, D.E., and C.A, Gleason. Fetal alcohol exposure alters cerebrovascular reactivity to VIP in adult sheep. Neonatology 93:45-51, 2008.
10. Britz G.W., I.-S. Park, C. Witt, J.R. Meno, A. Chowdhary, T.-S. Nguyen, H.R. Winn, and A.C. Ngai. Impairment of intracerebral arteriole dilation responses after subarachnoid hemorrhage. Accepted for publication, J. Neurosurg., 2009.

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