George Herok is a Physiologist with special interest in the structure and function of the tear film. His PhD was studying the characteristics and function of ion channels in the lacrimal glands of the rabbit.This project was part of the Dry Eye programme conducted at the CRC for Eye Research and Technology at UNSW and employed highly complex electrophysiological techniques (patch clamp) and cell culture techniques. He is currently doing research at UWS with Associate Professor Thomas Millar studying the role of meibomian lipids on tear evaporation rates.George has 8 peer- reviewed publications in international journals with two being published in high impact journals. George has gained wide clinical experience both prior to commencement of his PhD and as a post-doctoral scientist and consequently has gained excellent communication skills. These experiences involved monitoring patients undergoing heart surgery and running the Pacemaker follow clinic at RPAH, conducting electrophysiological studies (Nasal Potential Difference tests) on both Cystic Fibrosis patients and non-CF subjects at Westmead Hospital and performing clinical trials on COPD and Asthmatic patients also at Westmead Hospital.In 2004 at the annual TSANZ conference George was awarded the CF/Roche prize for the best oral presentation worth $500. In 2002 George was involved in a successful NH&MRC grant (epithelial ion transport defects in Cystic Fibrosis Pathophysiology and Treatment).George has a high affinity for teaching and enjoys very much student contact endeavouring always to promulgate complex scientific ideas and processes simply and concisely to students. He teaches Physiology to a variety of students including Nursing, Science and Medical students.He has also been involved with the new medical degree at UWS as a tutor in problem based learning.
Can supervise: YES
Reseach interests are currently in studying the effect of Meibomian lipids and tear proteins on evaporation rates.
Main teaching area is Physiology although have given Biochemistry lectures to Notre Dame medical students.Major areas of Physiology include neurophysiology, sensory physiology, cardiac-vascular and respiratory.
Chen, H, Chan, YL, Linnane, C, Mao, Y, Anwer, AG, Sapkota, A, Annissa, TF, Herok, G, Vissel, B, Oliver, BG, Saad, S & Gorrie, CA 2018, 'L-Carnitine and extendin-4 improve outcomes following moderate brain contusion injury.', Scientific reports, vol. 8, no. 1.View/Download from: Publisher's site
There is a need for pharmaceutical agents that can reduce neuronal loss and improve functional deficits following traumatic brain injury (TBI). Previous research suggests that oxidative stress and mitochondrial dysfunction play a major role in neuronal damage after TBI. Therefore, this study aimed to investigate two drugs known to have antioxidant effects, L-carnitine and exendin-4, in rats with moderate contusive TBI. L-carnitine (1.5 mM in drinking water) or exendin-4 (15 µg/kg/day, ip) were given immediately after the injury for 2 weeks. Neurological function and brain histology were examined (24 h and 6 weeks post injury). The rats with TBI showed slight sensory, motor and memory functional deficits at 24 h, but recovered by 6 weeks. Both treatments improved sensory and motor functions at 24 h, while only exendin-4 improved memory. Both treatments reduced cortical contusion at 24 h and 6 weeks, however neither affected gliosis and inflammatory cell activation. Oxidative stress was alleviated and mitochondrial reactive oxygen species was reduced by both treatments, however only mitochondrial functional marker protein transporter translocase of outer membrane 20 was increased at 24 h post injury. In conclusion, L-carnitine and exendin-4 treatments immediately after TBI can improve neurological functional outcome and tissue integrity by reducing oxidative stress.
Chen, H, Kelly, M, Hayes, C, van Reyk, D & Herok, G 2016, 'The use of simulation as a novel experiential learning module in undergraduate science pathophysiology education', ADVANCES IN PHYSIOLOGY EDUCATION, vol. 40, no. 3, pp. 335-341.View/Download from: Publisher's site
Chen, H, Chan, YL, Nguyen, LT, Mao, Y, de Rosa, A, Beh, IT, Chee, C, Oliver, B, Herok, G, Saad, S & Gorrie, C 2016, 'Moderate traumatic brain injury is linked to acute behaviour deficits and long term mitochondrial alterations', CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, vol. 43, no. 11, pp. 1107-1114.View/Download from: Publisher's site
Herok, GH, Mudgil, P & Millar, TJ 2009, 'The Effect of Meibomian Lipids and Tear Proteins on Evaporation Rate under Controlled In Vitro Conditions', CURRENT EYE RESEARCH, vol. 34, no. 7, pp. 589-597.View/Download from: Publisher's site
Herok, GH, Millar, TJ, Anderton, PJ & Martin, DK 2008, 'Role of Chloride Channels in Regulating the Volume of Acinar Cells of the Rabbit Superior Lacrimal Gland', Investigative Ophthalmology & Visual Science, vol. 49, no. 12, pp. 5517-5525.View/Download from: Publisher's site
PURPOSE. To characterize the outward chloride currents (Cl-OR) in single acinar cells isolated from the rabbit superior lacrimal gland (RSLG) to investigate the hypothesis that Cl-OR may have a role in regulating the volume of RSLG acini. METHODS. Cl-OR
Herok, G & Middleton, P 2001, 'Extracellular divalent ions appear to modulate ion transport across the normal nasal epithelium', Respirology, vol. 6, no. SUPPL. 1.
Cystic Fibrosis (CF) is an autosomal recessive disorder characterised by abnormal ion transport across the respiratory epithelium, which can be assessed using the nasal potential difference (PD). We have previously demonstrated that CF patients do not respond to a low Cl" solution in the presence of Ca-+, but exhibit a small sustained hyperpolarization when exposed to a Ca+ free low Cl" solution. To determine whether a similar response occurs in non-CF individuals, we have examined the effect of extracellular divalent ions on the low Cl" response. Methods: Nasal PD was measured using standard techniques (Ear Respir J1994:7:2050-2056) in 7 normal subjects. The absolute values of PD are reported, which was always lumen negative. The following sequence of solutions were perfused: (1) Krebs HEPES diluent (containing 2mM Ca-+ and ImM Mg2T), (2) amiloride (lOOuM), (3) amiloride (lOOjiM) in low Cl" (6mM) Krebs HEPES, (4) amiloride / low Cl- so!ution(with no added divalent ions), (5) amiloride / low Cl" solution (with divalent ions). Results: The baseline nasal PD was 13.2 (1.3) mV with Krebs HEPES solution, decreasing to 4.2 ( 1.1 ) mV with amiloride. Perfusion with low Cl" solution increased the PD to 21.6(1.7). Following the change to divalent free solutions, the PD gradually increased by a further 6.6 (0.8) mV over 5 minutes to 28.2 (1.9) mV. Washout of the divalent free solution was associated with a decrease in the PD back to 21.1(2.1) mV. Conclusions: The additional low Cl" response measured following removal of divalent ions was 6.6 (0.8) mV, compared with our previous study in the CF subjects of [8.0 (0.7) mV, n=7]. This suggests that extracellular Ca2f modulates ion transport in both CF and non CF airway epithelia, possibly via a similar ion transport mechanism.
Middleton, P & Herok, G 2001, 'Hypertonic responses of the cystic fibrosis airway', Respirology, vol. 6, no. SUPPL. 1.
Aerosols of Hypertonie saline and mannitol improve mucociliary clearance and are currently being investigated as potential new treatments for suppurative lung diseases. We have recently demonstrated that the normal human airway responds to addition of hypertonic saline to the airway surface liquid (ASL) with a decrease in potential difference (PD). This rapid and reversible response was related to changes in the ASL Cl" concentration, and not osmolarity, as mannitol did not decrease PD in the normal subjects. To further investigate the mechanisms underlying these responses, we have now compared the effects of these hypertonic solutions on nasal PD in 6 subjects with cystic fibrosis (CF). Methods: Nasal PD was measured using standard techniques (EtirRespirJ 1994:7:2050-2056). On separate days, the effect of addition of 500 mM sodium chloride and IM mannitol to the Krebs HEPES diluent was tested, either with or without pretreatment with the sodium channel blocker amiloride. Results: Addition of mannitol to the Krebs HEPES perfusate significantly (pO.OOl ) decreased PD (became less negative), with a mean (SEM) change of 22.1 (4.6) mV in the CF subjects. Following amiloride pretreatment, the mannitol response was almost completely abolished [5.7 (1.2) mV]. Addition of 500 mM sodium chloride significantly (p<0.001) decreased nasal PD by 33.7 (5.2) mV. Following amiloride pretreatment the saline response was significantly decreased to 15.8 (2.0) mV. Discussion: This data suggests that a large hypertonic stimulus (mannitol) decreases Na+ absorption across the CF airway. The significantly greater response to additional saline suggests a dual response - both to the osmolarity and to the increased sodium chloride concentration in the ASL. The CF airway responses to hypertonic saline and mannitol solutions are qualitatively different from our previous work in non-CF subjects. This suggests that CF related ion transport mechanisms may be involved in the hypertonic responses.
Herok, GH, Millar, TJ, Anderton, PJ & Martin, DK 2000, 'Role of chloride channels in regulating the volume of acinar cells in the rabbit superior lacrimal gland', MOLECULAR BIOLOGY OF THE CELL, vol. 11, pp. 221A-221A.
Herok, GH, Millar, TJ, Anderton, PJ & Martin, DK 2000, 'Role Of Chloride Channels In Regulating The Volume Of Acinar Cells In The Rabbit Superior Lacrimal Gland', Molecular Biology Of The Cell, vol. 11, pp. 1-1.
Herok, GH, Millar, TJ, Anderton, PJ & Martin, DK 1998, 'Characterization Of An Inwardly Rectifying Potassium Channel In The Rabbit Superior Lacrimal Gland', Investigative Ophthalmology & Visual Science, vol. 39, no. 2, pp. 308-314.
PURPOSE. To characterize the properties of an inwardly rectifying K+ (K-IR) current in fresh, enzymatically isolated acinar cells from the rabbit superior lacrimal gland. METHODS. New Zealand White rabbits of both sexes were killed by injecting 45 mg/kg
Herok, GH, Millar, TJ, Anderton, PJ & Martin, DK 1998, 'Inward-rectifying Potassium Channels In The Rabbit Superior Lacrimal Gland', Lacrimal Gland, Tear Film, And Dry Eye Syndromes 2, vol. 438, pp. 205-208.
Herok, GH, Millar, TJ, Anderton, PJ & Martin, DK 1998, 'Voltage- And Ca2+-dependent Chloride Current Activated By Hyposmotic And Hyperosmotic Stress In Rabbit Superior Lacrimal Acinar Cells', Lacrimal Gland, Tear Film, And Dry Eye Syndromes 2, vol. 438, pp. 129-132.
Millar, TJ, Herok, GH, Koutavas, H, Martin, DK & Anderton, PJ 1996, 'Immunohistochemical And Histochemical Characterisation Of Epithelial Cells Of Rabbit Lacrimal Glands In Tissue Sections And Cell Cultures', Tissue & Cell, vol. 28, no. 3, pp. 301-312.View/Download from: Publisher's site
The purpose of this study was to establish conditions for isolation and long term culture of acinar cells from the Harderian gland, and superior and inferior lacrimal glands of the rabbit and to compare the in vitro growth patterns of cultured cells from