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Papers by Ronald Young

Research paper thumbnail of Motor Pathway Analysis in HAM/TSP Using Magnetic Stimulation and F-waves

Canadian Journal of Neurological Sciences, Feb 1, 1998

Background: Tropical Spastic Paraparesis/HTLV-I Associated Myelopathy (HAM/TSP) is a chronic, pro... more Background: Tropical Spastic Paraparesis/HTLV-I Associated Myelopathy (HAM/TSP) is a chronic, progressive myelopathy endemic to the Caribbean. In HAM/TSP, peripheral motor pathways have been assessed using electromyography and nerve conduction studies; central motor pathways have been assessed to a limited extent using electrocortical stimulation. We used magnetic cortical stimulation (a painless alternative to electrocortical stimulation) and F-wave analysis to study conduction in the central and peripheral motor pathways in 18 HTLV-I seropositive, Jamaican TSP patients (ages 29-70 years; duration of symptoms 3-20 years) and 22 normal controls. Methods: Magnetic cortical stimulation was effected using a 9 cm diameter undamped MES10 coil. F-waves and M-responses were elicited by electrical stimulation of the ulnar nerve at the wrist, and deep peroneal stimulation at the knee. Stimulation and recording of response latencies in abductor digitii minimi (ADM) and tibialis anterior (TA) were carried out using a Cadwell Excel system. Results: With cortical stimulation, response latencies (TMCTs) to ADM and TA were prolonged in the patients relative to controls. F-wave and M-response latencies were unaffected, suggesting no peripheral pathology. Latency (CMCT) between cortex and lumbar cord was significantly prolonged; that between cortex and C7/T1, also, but less markedly (P < 0.0005). Amplitudes of cortically evoked responses were significantly reduced only in the lower limbs (TA). CMCT increased as the disease progressed from mild to moderate, thereafter remaining largely unchanged. Conclusions: Meta-analysis of interlaboratory control data revealed no significant differences in TMCTs between our controls and others studied using similar techniques. The observations are consistent with pathology affecting mainly the thoracolumbar cord in HAM/TSP. RESUME: Analyse des voies motrices dans la MAV/PST au moyen de la stimulation magnetique et des ondes F. Introduction: La myelopathic associee au VLTH/parapar6sie spastique tropicale MAV/PST est une myelopathic progressive chronique endemique dans les CaraTbes. Nous avons evalue les voies motrices peripheYiques dans la MAV/PST au moyen de l'electromyographie et d'etudes de la conduction nerveuse et, de facon plus limited, les voies motrices centrales au moyen de la stimulation electrocorticale. Nous avons utilise la stimulation magneYique corticale, une alternative indolore a la stimulation dlectrocorticale et l'analyse des ondes F pour eYudier la conduction dans les voies motrices centrales et peYipheriques chez 18 patients jamai'cains seropositifs pour le VLTH-1 atteints de PST, agds de 29 a 70 ans et symptomatiques depuis 3 a 20 ans, et 22 sujets contr61es normaux. Methodes: La stimulation corticale magnetique a ete effectuee au moyen d'une inductance MES 10 non amortie de 9 cm de diametre. Les ondes F et les reponses M etaient obtenues par stimulation electrique du nerf radial au poignet et du nerf tibial anterieur au genou. La stimulation et l'enregistrement des temps de latence dans l'abducteur du V e doigt (AVD) et dans le jambier ant6rieur (JA) ont ete effectues au moyen d'un systeme Cadwell Excel. Resultats: Avec la stimulation corticale, les temps de latence (TLSCs) de l'AVD et du JA etaient prolonged chez les patients. Les ondes F et les latences M n'6taient pas atteintes, suggerant qu'il n'existait pas de pathologie peripherique. Le temps de latence entre le cortex et la moelle lombaire etait significativement prolonge, de meme qu'entre la cortex et C7/D1, mais beaucoup moins (p < 0.0005). L'amplitude des reponses evoquees corticales etait significativement diminu6e seulement aux membres infeYieurs (JA). Le temps de latence augmentait a mesure que la maladie progressait de 16gere a modeYfie et demeurait stable par la suite. Conclusions: Une meta-analyse de donn&s controles interlaboratoires n'a pas revdle' de differences significatives entre les TLSCs de nos controles et d'autres sujets etudids par des techniques semblables. Ces observations sont compatibles avec une pathologie affectant surtout la moelle dorsolombaire dans la MAV/PST.

Research paper thumbnail of Nervous control of ventilation in the shore crab carcinus maenas

CCKCIUL'ICNS. ACKHQWLEDG&fEimj. Appendix I « The main features of a Digital Computer Pi mil at io... more CCKCIUL'ICNS. ACKHQWLEDG&fEimj. Appendix I « The main features of a Digital Computer Pi mil at ion DeKir^ed by Mr# P. R. Balch to simulate the characteristics of sciall neuronal networks. appendix 4.~ . Jerivatlon of the Expected I ndoia Latency Distribution for the Occurrence of a test spike in the interspike intervals of a reference spike train, given the frequency distribution of the reference intervale. REFERENCES.

Research paper thumbnail of Chronic stimulation of the Kölliker-Fuse nucleus region for relief of intractable pain in humans

Journal of Neurosurgery, 1992

✓ Chronic electrical stimulation in the periventricular or periaqueductal gray matter regions and... more ✓ Chronic electrical stimulation in the periventricular or periaqueductal gray matter regions and the thalamic somatosensory relay nuclei (ventralis posteromedialis and ventralis posterolateralis) provides long-term pain relief in about 50% of patients with intractable pain refractory to other conservative and/or surgical measures. To enhance the success of electrical stimulation in relief of pain, alternative brain and brain-stem targets have been sought. A series of laboratory studies indicated that the Kölliker-Fuse nucleus and the parabrachial region may provide appropriate alternatives to the “classic” targets. This report describes six patients with intractable chronic pain of nociceptive or central origin, in whom an electrode was stereotactically implanted in the region of the Kölliker-Fuse nucleus. Kölliker-Fuse nucleus stimulation alone or in combination with stimulation in the periaqueductal/periventricular gray matter region or the somatosensory thalamic nuclei provided ...

Research paper thumbnail of Cold-induced elevation of forearm vascular resistance is inversely related to birth weight

Journal of Human Hypertension, 2005

Fetal growth retardation has been linked to elevated blood pressure in adult life. This associati... more Fetal growth retardation has been linked to elevated blood pressure in adult life. This association between birth weight and blood pressure is present in childhood and is amplified with age. However, the mechanisms that underlie this association are largely unknown. We examined the relationship between birth weight and forearm vascular resistance and forearm blood flow in children aged 9-12.7 years. A total of 58 children were randomly selected from a cohort of 1610 born at the University Hospital of the West Indies in Jamaica where adequate antenatal and delivery records were available. Blood pressure, heart rate and forearm blood flow (by venous occlusion plethysmography) were measured at rest and after cold pressor and mental arithmetic tests. There was a significant inverse correlation between birth weight and the change in the vascular resistance for the cold pressor test (r ¼ À0.47; Po0.001) and the mental arithmetic stress test (r ¼ À0.26; P ¼ 0.05). The log ratio of vascular resistance under stress to resting decreased by 0.289 units per kg of birth weight (95% CI: 0.145-0.434; P ¼ 0.0002). Lower birth weight is associated with increased vascular responsiveness. Increased vascular resistance might be one mechanism linking fetal growth to subsequent elevated blood pressure.

Research paper thumbnail of Neural factors influence the degeneration of muscle fibers in the chelae of snapping shrimps

Molecular and Chemical Neuropathology

The asymmetric pincer and snapper claws in the snapping shrimp differ in external morphology and ... more The asymmetric pincer and snapper claws in the snapping shrimp differ in external morphology and musculature. The snapper is a massive claw used for displays and defense; the pincer is small and slender, used for feeding and burrowing. The snapper has only slow muscle fibers; the pincer has both slow and fast. Removal or denervation of the snapper claw induces transformation of the contralateral pincer to a snapper type of claw at the subsequent molt. A removed claw regenerates as a pincer type, as long as the innervation of the remaining claw is intact. Fast muscle fibers, found exclusively in the pincer claw, normally degenerate completely within 10 d after the moult, which transforms the pincer to a snapper. Morphological transformation of the pincer following removal of the snapper claw can occur even if the pincer claw is denervated. Denervation of the pincer, however, delays degeneration of the fast fibers, increasing the estimated half-time for muscle degeneration, from 4.4 + 0.2 to 19.5 + 0.8. d after the transforming moult. Neural influences therefore are involved both in the determination of the morphology of the claw and in the induction of degenerative changes during the remodeling of an existing claw.

Research paper thumbnail of Establishment and maintenance of claw bilateral asymmetry in snapping shrimps

Journal of Experimental Zoology

Research paper thumbnail of Neuropharmacological modulation of swimming activity and life span in a digenean parasite, Cercaria caribbea LXXI cable

Comparative Biochemistry and Physiology Part C: Comparative Pharmacology

Research paper thumbnail of Ultrastructural and neuropharmacological findings in the nerve/muscle system of a digenean (Cercaria caribbea LXXI cable)

Comparative Biochemistry and Physiology Part C: Comparative Pharmacology

Surface morphology and organization of the neuromuscular system in Cercaria caribbea LXXI are inv... more Surface morphology and organization of the neuromuscular system in Cercaria caribbea LXXI are investigated using scanning and transmission electron microscopy, respectively. 2. Direct and indirect (sarconeural) nerve-muscle junctions are identified in the cercarial tail. 3. Synaptic vesicles at the direct neuromuscular junctions suggest cholinergic or aminoacidergic transmission. Those at the sarconeural junctions suggest catecholaminergic and/or serotonergic transmission. 4. Acetylcholinesterase and non-specific cholinesterases were found in high concentrations in the proximal and distal &ail. 5. Fluorescence histochemistry showed primary catecholamines and S-HT in the body and tail. 6. S-HT in the tail may represent a slowly depleted store, perhaps associated with energy availability and utilization.

Research paper thumbnail of Photoreceptor evoked potentials and phototactic behaviour in Cercaria caribbea LXXI cable

Comparative biochemistry and physiology. A, Comparative physiology, 1987

1. Transient potential changes evoked in response to light stimuli, and presumably arising from r... more 1. Transient potential changes evoked in response to light stimuli, and presumably arising from rhabdomeric eye-spots in the cercarial body, were recorded for the first time, to our knowledge, in helminth parasites. 2. Pigmented Cercaria caribbea LXXI gave a very slowly adapting response to maintained light stimulus, while a non-pigmented variety appeared to emit a stronger, rapidly adapting response to light onset. 3. Swimming towards a directional light source is disrupted by several neuropharmacological agents, which presumably disturb synaptic transmission in the nerve/muscle system. 4. The light evoked potentials were unaffected by these same agents and therefore, appeared to be directly recorded receptor potentials.

Research paper thumbnail of The effect of sub-lethal doses of dieldrin on resting and active metabolism in two species of shrimps

Comparative biochemistry and physiology. C, Comparative pharmacology and toxicology, 1986

The effects of dieldrin on the active (VaO2) and resting (VrO2) oxygen consumption rates of the s... more The effects of dieldrin on the active (VaO2) and resting (VrO2) oxygen consumption rates of the shrimps Macrobrachium faustinum (De Sassure) and Macrobrachium amazonicum (Heller) were studied during exposure for 4 days at 0.01 p.p.b. and 7 days at 0.0002 p.p.b., respectively. The VrO2 of M. faustinum increased significantly (P less than 0.01) by 48% but the VaO2 decreased by 13%. The VrO2 and VaO2 decreased by 43 and 70%, respectively, in M. amazonicum. Thus, in both species the aerobic metabolic scope for activity decreased. The increased resting metabolic rate of the indigenous M. faustinum is ascribed to energy consuming responses which allow compensation for the effects of the stressor. The stressor may be said to have moved this species into a metabolic "zone of compensation". The decreased resting metabolic rate of the pond-cultured M. amazonicum is ascribed to greater susceptibility, more extensive metabolic breakdown and failure of compensatory responses. This spec...

Research paper thumbnail of The effect of sub-lethal doses of dieldrin on the ventilatory and cardiac activity in two species of shrimps

Comparative biochemistry and physiology. C, Comparative pharmacology and toxicology, 1986

The effect of dieldrin on the heart and ventilatory activity in the shrimps Macrobranchium fausti... more The effect of dieldrin on the heart and ventilatory activity in the shrimps Macrobranchium faustinum and Macrobrachium amazonicum was studied over 4 and 7 day exposure periods, respectively. In M. faustinum, ventilatory rate increased by 43% and heart rate by 14.4%. In M. amazonicum, the ventilatory and heart rates decreased by 21 and 6%, respectively. In M. amazonicum ventilatory reversal frequency, an index of respiratory stress, was 6.7 times higher than the control values. All the changes, except for M. amazonicum heart rate were significant at the 0.01 level of probability.

Research paper thumbnail of A thermostable zone in survivorship and metabolism of a tropical marine cercaria

A thermostable zone in survivorship and metabolism of a tropical marine cercaria

Comparative Biochemistry and Physiology Part A: Physiology, 1984

ABSTRACT 1.1. Survivorship curves and their parameters are determined at different temperatures f... more ABSTRACT 1.1. Survivorship curves and their parameters are determined at different temperatures for the marine Cercaria caribbea LXXI (Cable).2.2. A relationship is demonstrated between Mean Expected Life Span and half life of the populations (t0.5) and it is argued that t0.5 is a good index of glycogen utilization rate.3.3. Q10 values for t0.5 computed on this basis were 5.8 between 10 and 20°C, 3.1 between 30 and 40°C and ∼- 1 between 20 and 30°C.4.4. The zone of thermostability corresponds with normal environmental temperatures for the cercariae and probably serves to maximize infectivity under prevailing environmental conditions.

Research paper thumbnail of Phase Coordination in the Cardiac and Ventilatory Rhythms of the Lobster Homarus Americanus

Phase Coordination in the Cardiac and Ventilatory Rhythms of the Lobster Homarus Americanus

SUMMARY 1. Relative co-ordination is demonstrated between the rhythms of the right and left scaph... more SUMMARY 1. Relative co-ordination is demonstrated between the rhythms of the right and left scaphognathites (SG) and between the heart and either right or left SG or both simultaneously. 2. The co-ordination between these rhythms results from mutual phase- dependent alteration of the period lengths as demonstrated by the phase- response curves for the interactions. 3. The standard deviation of

Research paper thumbnail of Neuropharmacological actions of some binuclear lanthanide(III) complexes

Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 2001

Binuclear lanthanide III compounds are of great interest because of the potential of their mutual... more Binuclear lanthanide III compounds are of great interest because of the potential of their mutual Ln ᎐Ln electronic couplings to produce unusually sharp images in magnetic resonance and fluorescence imaging of biological tissue. The toxicity and neuropharmacological properties of the water soluble and stable neutral binuclear complex w Ž .x La api were compared with those of binuclear complexes with lower water stability, and the components used in their 2 . Ž . syntheses. The order of the 24-h LD mgrkg body wt. of the compounds in mice was: salicylaldehyde 2.24 -H api 50 3 Ž . w 1 Ž . x Ž . Ž . 2 Ž .x Ž . Ž . w 3 32.3 -La L NO и H O 35.1triethylenetetramine 38.5 -La L NO 43.4 -La NO и 5H O s GdL 2 34 2 2 3 2 33 2 Ž .x Ž . 4 Ž . Ž . w Ž .x Ž . NO 45.7 -La L NO и CH OH 49.6 -La api ) 160 . These compounds induced convulsions, urination 3 2 2 3 4 3 2 w Ž .x and defecation in mice. Due to the relatively very low toxicity of La api , its mode of action was explored. Its 2 proconvulsant action may possibly involve an interaction of undissociated complex with muscarinic receptors, and is reversed by atropine.

Research paper thumbnail of Effects of embryonic exposure to α-lipoic acid or ascorbic acid on hatching rate and development of zebrafish (Danio rerio)

Aquaculture Research, 2012

This study investigates the e¡ects of embryonic exposure to two di¡erent antioxidants on growth a... more This study investigates the e¡ects of embryonic exposure to two di¡erent antioxidants on growth and development in ¢sh. Zebra¢sh (Danio rerio) embryos (100 per group) were exposed to lipoic acid (LA, 61 2 mM) or ascorbic acid (AA, 100^200 mM) and the hatching rate, standard lengths (SL) at hatching, development and growth post-hatching monitored. The SLs at hatching were increased (Po0.05) in both antioxidant-exposed groups relative to the controls, with no e¡ect on yolk reserves. This enhanced development persisted up to 15 days post hatching. At hatching, cell proliferation rates (Po0.0005) and basic ¢broblast growth factor (Po0.001), were greater in the antioxidant-exposed ¢sh than in the controls (0 mM antioxidant); no oxidative DNA damage was detected (P40.05). Activity of the endogenous antioxidant enzyme superoxide dismutase was greater (Po0.001) in LA-treated ¢sh than in the controls. The results suggest that embryonic treatment of zeb-ra¢sh with LA or AA during embryogenesis enhanced cell proliferation, leading to increased somatic growth in the larval stages, persisting into the juvenile stage. The ¢ndings support the treatment of embryonic ¢sh with antioxidants for enhanced results in aquaculture.

Research paper thumbnail of Electrophysiological assessment of brain function in severe malnutrition

Electrophysiological assessment of brain function in severe malnutrition

Acta Paediatrica, 1995

Brain function in 10 severely malnourished children and matched controls was assessed using spect... more Brain function in 10 severely malnourished children and matched controls was assessed using spectral analysis of electroencephalographic responses to photic driving during slow-wave sleep. The percentage power in the classical EEG broad-band domains was derived from temporo-occipital records. The malnourished group (5-23 months old; z-score height-for-age -3.2 +/- 0.3, weight-for-height -2.5 +/- 0.3) were tested on admission and on discharge from hospital. No significant differences were found between admission and discharge. Significant differences were found between malnourished and control groups, in the alpha 1 band in the undriven EEG, and in the alpha/beta 1 power ratio while driving at 8 Hz. These electrophysiological abnormalities, persisting despite somatic rehabilitation, must be associated with the chronic rather than the acute aspects of malnutrition, and can index the deviation of brain function from normality.

Research paper thumbnail of Effect of exercise therapy on lipid profile and oxidative stress indicators in patients with type 2 diabetes

BMC Complementary and Alternative Medicine, 2008

Background: Yoga has been shown to be a simple and economical therapeutic modality that may be co... more Background: Yoga has been shown to be a simple and economical therapeutic modality that may be considered as a beneficial adjuvant for type 2 diabetes mellitus. This study investigated the impact of Hatha yoga and conventional physical training (PT) exercise regimens on biochemical, oxidative stress indicators and oxidant status in patients with type 2 diabetes. Methods: This prospective randomized study consisted of 77 type 2 diabetic patients in the Hatha yoga exercise group that were matched with a similar number of type 2 diabetic patients in the conventional PT exercise and control groups. Biochemical parameters such as fasting blood glucose (FBG), serum total cholesterol (TC), triglycerides, low-density lipoprotein (LDL), very low-density lipoproteins (VLDL) and high-density lipoprotein (HDL) were determined at baseline and at two consecutive three monthly intervals. The oxidative stress indicators (malondialdehyde-MDA, protein oxidation-POX, phospholipase A2-PLA2 activity) and oxidative status [superoxide dismutase (SOD) and catalase activities] were measured. Results: The concentrations of FBG in the Hatha yoga and conventional PT exercise groups after six months decreased by 29.48% and 27.43% respectively (P < 0.0001) and there was a significant reduction in serum TC in both groups (P < 0.0001). The concentrations of VLDL in the managed groups after six months differed significantly from baseline values (P = 0.036). Lipid peroxidation as indicated by MDA significantly decreased by 19.9% and 18.1% in the Hatha yoga and conventional PT exercise groups respectively (P < 0.0001); whilst the activity of SOD significantly increased by 24.08% and 20.18% respectively (P = 0.031). There was no significant difference in the baseline and 6 months activities of PLA2 and catalase after six months although the latter increased by 13.68% and 13.19% in the Hatha yoga and conventional PT exercise groups respectively (P = 0.144). Conclusion: The study demonstrate the efficacy of Hatha yoga exercise on fasting blood glucose, lipid profile, oxidative stress markers and antioxidant status in patients with type 2 diabetes and suggest that Hatha yoga exercise and conventional PT exercise may have therapeutic preventative and protective effects on diabetes mellitus by decreasing oxidative stress and improving antioxidant status.

Research paper thumbnail of Motor Pathway Analysis in HAM/TSP Using Magnetic Stimulation and F-waves

Canadian Journal of Neurological Sciences, Feb 1, 1998

Background: Tropical Spastic Paraparesis/HTLV-I Associated Myelopathy (HAM/TSP) is a chronic, pro... more Background: Tropical Spastic Paraparesis/HTLV-I Associated Myelopathy (HAM/TSP) is a chronic, progressive myelopathy endemic to the Caribbean. In HAM/TSP, peripheral motor pathways have been assessed using electromyography and nerve conduction studies; central motor pathways have been assessed to a limited extent using electrocortical stimulation. We used magnetic cortical stimulation (a painless alternative to electrocortical stimulation) and F-wave analysis to study conduction in the central and peripheral motor pathways in 18 HTLV-I seropositive, Jamaican TSP patients (ages 29-70 years; duration of symptoms 3-20 years) and 22 normal controls. Methods: Magnetic cortical stimulation was effected using a 9 cm diameter undamped MES10 coil. F-waves and M-responses were elicited by electrical stimulation of the ulnar nerve at the wrist, and deep peroneal stimulation at the knee. Stimulation and recording of response latencies in abductor digitii minimi (ADM) and tibialis anterior (TA) were carried out using a Cadwell Excel system. Results: With cortical stimulation, response latencies (TMCTs) to ADM and TA were prolonged in the patients relative to controls. F-wave and M-response latencies were unaffected, suggesting no peripheral pathology. Latency (CMCT) between cortex and lumbar cord was significantly prolonged; that between cortex and C7/T1, also, but less markedly (P < 0.0005). Amplitudes of cortically evoked responses were significantly reduced only in the lower limbs (TA). CMCT increased as the disease progressed from mild to moderate, thereafter remaining largely unchanged. Conclusions: Meta-analysis of interlaboratory control data revealed no significant differences in TMCTs between our controls and others studied using similar techniques. The observations are consistent with pathology affecting mainly the thoracolumbar cord in HAM/TSP. RESUME: Analyse des voies motrices dans la MAV/PST au moyen de la stimulation magnetique et des ondes F. Introduction: La myelopathic associee au VLTH/parapar6sie spastique tropicale MAV/PST est une myelopathic progressive chronique endemique dans les CaraTbes. Nous avons evalue les voies motrices peripheYiques dans la MAV/PST au moyen de l'electromyographie et d'etudes de la conduction nerveuse et, de facon plus limited, les voies motrices centrales au moyen de la stimulation electrocorticale. Nous avons utilise la stimulation magneYique corticale, une alternative indolore a la stimulation dlectrocorticale et l'analyse des ondes F pour eYudier la conduction dans les voies motrices centrales et peYipheriques chez 18 patients jamai'cains seropositifs pour le VLTH-1 atteints de PST, agds de 29 a 70 ans et symptomatiques depuis 3 a 20 ans, et 22 sujets contr61es normaux. Methodes: La stimulation corticale magnetique a ete effectuee au moyen d'une inductance MES 10 non amortie de 9 cm de diametre. Les ondes F et les reponses M etaient obtenues par stimulation electrique du nerf radial au poignet et du nerf tibial anterieur au genou. La stimulation et l'enregistrement des temps de latence dans l'abducteur du V e doigt (AVD) et dans le jambier ant6rieur (JA) ont ete effectues au moyen d'un systeme Cadwell Excel. Resultats: Avec la stimulation corticale, les temps de latence (TLSCs) de l'AVD et du JA etaient prolonged chez les patients. Les ondes F et les latences M n'6taient pas atteintes, suggerant qu'il n'existait pas de pathologie peripherique. Le temps de latence entre le cortex et la moelle lombaire etait significativement prolonge, de meme qu'entre la cortex et C7/D1, mais beaucoup moins (p < 0.0005). L'amplitude des reponses evoquees corticales etait significativement diminu6e seulement aux membres infeYieurs (JA). Le temps de latence augmentait a mesure que la maladie progressait de 16gere a modeYfie et demeurait stable par la suite. Conclusions: Une meta-analyse de donn&s controles interlaboratoires n'a pas revdle' de differences significatives entre les TLSCs de nos controles et d'autres sujets etudids par des techniques semblables. Ces observations sont compatibles avec une pathologie affectant surtout la moelle dorsolombaire dans la MAV/PST.

Research paper thumbnail of Nervous control of ventilation in the shore crab carcinus maenas

CCKCIUL'ICNS. ACKHQWLEDG&fEimj. Appendix I « The main features of a Digital Computer Pi mil at io... more CCKCIUL'ICNS. ACKHQWLEDG&fEimj. Appendix I « The main features of a Digital Computer Pi mil at ion DeKir^ed by Mr# P. R. Balch to simulate the characteristics of sciall neuronal networks. appendix 4.~ . Jerivatlon of the Expected I ndoia Latency Distribution for the Occurrence of a test spike in the interspike intervals of a reference spike train, given the frequency distribution of the reference intervale. REFERENCES.

Research paper thumbnail of Chronic stimulation of the Kölliker-Fuse nucleus region for relief of intractable pain in humans

Journal of Neurosurgery, 1992

✓ Chronic electrical stimulation in the periventricular or periaqueductal gray matter regions and... more ✓ Chronic electrical stimulation in the periventricular or periaqueductal gray matter regions and the thalamic somatosensory relay nuclei (ventralis posteromedialis and ventralis posterolateralis) provides long-term pain relief in about 50% of patients with intractable pain refractory to other conservative and/or surgical measures. To enhance the success of electrical stimulation in relief of pain, alternative brain and brain-stem targets have been sought. A series of laboratory studies indicated that the Kölliker-Fuse nucleus and the parabrachial region may provide appropriate alternatives to the “classic” targets. This report describes six patients with intractable chronic pain of nociceptive or central origin, in whom an electrode was stereotactically implanted in the region of the Kölliker-Fuse nucleus. Kölliker-Fuse nucleus stimulation alone or in combination with stimulation in the periaqueductal/periventricular gray matter region or the somatosensory thalamic nuclei provided ...

Research paper thumbnail of Cold-induced elevation of forearm vascular resistance is inversely related to birth weight

Journal of Human Hypertension, 2005

Fetal growth retardation has been linked to elevated blood pressure in adult life. This associati... more Fetal growth retardation has been linked to elevated blood pressure in adult life. This association between birth weight and blood pressure is present in childhood and is amplified with age. However, the mechanisms that underlie this association are largely unknown. We examined the relationship between birth weight and forearm vascular resistance and forearm blood flow in children aged 9-12.7 years. A total of 58 children were randomly selected from a cohort of 1610 born at the University Hospital of the West Indies in Jamaica where adequate antenatal and delivery records were available. Blood pressure, heart rate and forearm blood flow (by venous occlusion plethysmography) were measured at rest and after cold pressor and mental arithmetic tests. There was a significant inverse correlation between birth weight and the change in the vascular resistance for the cold pressor test (r ¼ À0.47; Po0.001) and the mental arithmetic stress test (r ¼ À0.26; P ¼ 0.05). The log ratio of vascular resistance under stress to resting decreased by 0.289 units per kg of birth weight (95% CI: 0.145-0.434; P ¼ 0.0002). Lower birth weight is associated with increased vascular responsiveness. Increased vascular resistance might be one mechanism linking fetal growth to subsequent elevated blood pressure.

Research paper thumbnail of Neural factors influence the degeneration of muscle fibers in the chelae of snapping shrimps

Molecular and Chemical Neuropathology

The asymmetric pincer and snapper claws in the snapping shrimp differ in external morphology and ... more The asymmetric pincer and snapper claws in the snapping shrimp differ in external morphology and musculature. The snapper is a massive claw used for displays and defense; the pincer is small and slender, used for feeding and burrowing. The snapper has only slow muscle fibers; the pincer has both slow and fast. Removal or denervation of the snapper claw induces transformation of the contralateral pincer to a snapper type of claw at the subsequent molt. A removed claw regenerates as a pincer type, as long as the innervation of the remaining claw is intact. Fast muscle fibers, found exclusively in the pincer claw, normally degenerate completely within 10 d after the moult, which transforms the pincer to a snapper. Morphological transformation of the pincer following removal of the snapper claw can occur even if the pincer claw is denervated. Denervation of the pincer, however, delays degeneration of the fast fibers, increasing the estimated half-time for muscle degeneration, from 4.4 + 0.2 to 19.5 + 0.8. d after the transforming moult. Neural influences therefore are involved both in the determination of the morphology of the claw and in the induction of degenerative changes during the remodeling of an existing claw.

Research paper thumbnail of Establishment and maintenance of claw bilateral asymmetry in snapping shrimps

Journal of Experimental Zoology

Research paper thumbnail of Neuropharmacological modulation of swimming activity and life span in a digenean parasite, Cercaria caribbea LXXI cable

Comparative Biochemistry and Physiology Part C: Comparative Pharmacology

Research paper thumbnail of Ultrastructural and neuropharmacological findings in the nerve/muscle system of a digenean (Cercaria caribbea LXXI cable)

Comparative Biochemistry and Physiology Part C: Comparative Pharmacology

Surface morphology and organization of the neuromuscular system in Cercaria caribbea LXXI are inv... more Surface morphology and organization of the neuromuscular system in Cercaria caribbea LXXI are investigated using scanning and transmission electron microscopy, respectively. 2. Direct and indirect (sarconeural) nerve-muscle junctions are identified in the cercarial tail. 3. Synaptic vesicles at the direct neuromuscular junctions suggest cholinergic or aminoacidergic transmission. Those at the sarconeural junctions suggest catecholaminergic and/or serotonergic transmission. 4. Acetylcholinesterase and non-specific cholinesterases were found in high concentrations in the proximal and distal &ail. 5. Fluorescence histochemistry showed primary catecholamines and S-HT in the body and tail. 6. S-HT in the tail may represent a slowly depleted store, perhaps associated with energy availability and utilization.

Research paper thumbnail of Photoreceptor evoked potentials and phototactic behaviour in Cercaria caribbea LXXI cable

Comparative biochemistry and physiology. A, Comparative physiology, 1987

1. Transient potential changes evoked in response to light stimuli, and presumably arising from r... more 1. Transient potential changes evoked in response to light stimuli, and presumably arising from rhabdomeric eye-spots in the cercarial body, were recorded for the first time, to our knowledge, in helminth parasites. 2. Pigmented Cercaria caribbea LXXI gave a very slowly adapting response to maintained light stimulus, while a non-pigmented variety appeared to emit a stronger, rapidly adapting response to light onset. 3. Swimming towards a directional light source is disrupted by several neuropharmacological agents, which presumably disturb synaptic transmission in the nerve/muscle system. 4. The light evoked potentials were unaffected by these same agents and therefore, appeared to be directly recorded receptor potentials.

Research paper thumbnail of The effect of sub-lethal doses of dieldrin on resting and active metabolism in two species of shrimps

Comparative biochemistry and physiology. C, Comparative pharmacology and toxicology, 1986

The effects of dieldrin on the active (VaO2) and resting (VrO2) oxygen consumption rates of the s... more The effects of dieldrin on the active (VaO2) and resting (VrO2) oxygen consumption rates of the shrimps Macrobrachium faustinum (De Sassure) and Macrobrachium amazonicum (Heller) were studied during exposure for 4 days at 0.01 p.p.b. and 7 days at 0.0002 p.p.b., respectively. The VrO2 of M. faustinum increased significantly (P less than 0.01) by 48% but the VaO2 decreased by 13%. The VrO2 and VaO2 decreased by 43 and 70%, respectively, in M. amazonicum. Thus, in both species the aerobic metabolic scope for activity decreased. The increased resting metabolic rate of the indigenous M. faustinum is ascribed to energy consuming responses which allow compensation for the effects of the stressor. The stressor may be said to have moved this species into a metabolic "zone of compensation". The decreased resting metabolic rate of the pond-cultured M. amazonicum is ascribed to greater susceptibility, more extensive metabolic breakdown and failure of compensatory responses. This spec...

Research paper thumbnail of The effect of sub-lethal doses of dieldrin on the ventilatory and cardiac activity in two species of shrimps

Comparative biochemistry and physiology. C, Comparative pharmacology and toxicology, 1986

The effect of dieldrin on the heart and ventilatory activity in the shrimps Macrobranchium fausti... more The effect of dieldrin on the heart and ventilatory activity in the shrimps Macrobranchium faustinum and Macrobrachium amazonicum was studied over 4 and 7 day exposure periods, respectively. In M. faustinum, ventilatory rate increased by 43% and heart rate by 14.4%. In M. amazonicum, the ventilatory and heart rates decreased by 21 and 6%, respectively. In M. amazonicum ventilatory reversal frequency, an index of respiratory stress, was 6.7 times higher than the control values. All the changes, except for M. amazonicum heart rate were significant at the 0.01 level of probability.

Research paper thumbnail of A thermostable zone in survivorship and metabolism of a tropical marine cercaria

A thermostable zone in survivorship and metabolism of a tropical marine cercaria

Comparative Biochemistry and Physiology Part A: Physiology, 1984

ABSTRACT 1.1. Survivorship curves and their parameters are determined at different temperatures f... more ABSTRACT 1.1. Survivorship curves and their parameters are determined at different temperatures for the marine Cercaria caribbea LXXI (Cable).2.2. A relationship is demonstrated between Mean Expected Life Span and half life of the populations (t0.5) and it is argued that t0.5 is a good index of glycogen utilization rate.3.3. Q10 values for t0.5 computed on this basis were 5.8 between 10 and 20°C, 3.1 between 30 and 40°C and ∼- 1 between 20 and 30°C.4.4. The zone of thermostability corresponds with normal environmental temperatures for the cercariae and probably serves to maximize infectivity under prevailing environmental conditions.

Research paper thumbnail of Phase Coordination in the Cardiac and Ventilatory Rhythms of the Lobster Homarus Americanus

Phase Coordination in the Cardiac and Ventilatory Rhythms of the Lobster Homarus Americanus

SUMMARY 1. Relative co-ordination is demonstrated between the rhythms of the right and left scaph... more SUMMARY 1. Relative co-ordination is demonstrated between the rhythms of the right and left scaphognathites (SG) and between the heart and either right or left SG or both simultaneously. 2. The co-ordination between these rhythms results from mutual phase- dependent alteration of the period lengths as demonstrated by the phase- response curves for the interactions. 3. The standard deviation of

Research paper thumbnail of Neuropharmacological actions of some binuclear lanthanide(III) complexes

Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 2001

Binuclear lanthanide III compounds are of great interest because of the potential of their mutual... more Binuclear lanthanide III compounds are of great interest because of the potential of their mutual Ln ᎐Ln electronic couplings to produce unusually sharp images in magnetic resonance and fluorescence imaging of biological tissue. The toxicity and neuropharmacological properties of the water soluble and stable neutral binuclear complex w Ž .x La api were compared with those of binuclear complexes with lower water stability, and the components used in their 2 . Ž . syntheses. The order of the 24-h LD mgrkg body wt. of the compounds in mice was: salicylaldehyde 2.24 -H api 50 3 Ž . w 1 Ž . x Ž . Ž . 2 Ž .x Ž . Ž . w 3 32.3 -La L NO и H O 35.1triethylenetetramine 38.5 -La L NO 43.4 -La NO и 5H O s GdL 2 34 2 2 3 2 33 2 Ž .x Ž . 4 Ž . Ž . w Ž .x Ž . NO 45.7 -La L NO и CH OH 49.6 -La api ) 160 . These compounds induced convulsions, urination 3 2 2 3 4 3 2 w Ž .x and defecation in mice. Due to the relatively very low toxicity of La api , its mode of action was explored. Its 2 proconvulsant action may possibly involve an interaction of undissociated complex with muscarinic receptors, and is reversed by atropine.

Research paper thumbnail of Effects of embryonic exposure to α-lipoic acid or ascorbic acid on hatching rate and development of zebrafish (Danio rerio)

Aquaculture Research, 2012

This study investigates the e¡ects of embryonic exposure to two di¡erent antioxidants on growth a... more This study investigates the e¡ects of embryonic exposure to two di¡erent antioxidants on growth and development in ¢sh. Zebra¢sh (Danio rerio) embryos (100 per group) were exposed to lipoic acid (LA, 61 2 mM) or ascorbic acid (AA, 100^200 mM) and the hatching rate, standard lengths (SL) at hatching, development and growth post-hatching monitored. The SLs at hatching were increased (Po0.05) in both antioxidant-exposed groups relative to the controls, with no e¡ect on yolk reserves. This enhanced development persisted up to 15 days post hatching. At hatching, cell proliferation rates (Po0.0005) and basic ¢broblast growth factor (Po0.001), were greater in the antioxidant-exposed ¢sh than in the controls (0 mM antioxidant); no oxidative DNA damage was detected (P40.05). Activity of the endogenous antioxidant enzyme superoxide dismutase was greater (Po0.001) in LA-treated ¢sh than in the controls. The results suggest that embryonic treatment of zeb-ra¢sh with LA or AA during embryogenesis enhanced cell proliferation, leading to increased somatic growth in the larval stages, persisting into the juvenile stage. The ¢ndings support the treatment of embryonic ¢sh with antioxidants for enhanced results in aquaculture.

Research paper thumbnail of Electrophysiological assessment of brain function in severe malnutrition

Electrophysiological assessment of brain function in severe malnutrition

Acta Paediatrica, 1995

Brain function in 10 severely malnourished children and matched controls was assessed using spect... more Brain function in 10 severely malnourished children and matched controls was assessed using spectral analysis of electroencephalographic responses to photic driving during slow-wave sleep. The percentage power in the classical EEG broad-band domains was derived from temporo-occipital records. The malnourished group (5-23 months old; z-score height-for-age -3.2 +/- 0.3, weight-for-height -2.5 +/- 0.3) were tested on admission and on discharge from hospital. No significant differences were found between admission and discharge. Significant differences were found between malnourished and control groups, in the alpha 1 band in the undriven EEG, and in the alpha/beta 1 power ratio while driving at 8 Hz. These electrophysiological abnormalities, persisting despite somatic rehabilitation, must be associated with the chronic rather than the acute aspects of malnutrition, and can index the deviation of brain function from normality.

Research paper thumbnail of Effect of exercise therapy on lipid profile and oxidative stress indicators in patients with type 2 diabetes

BMC Complementary and Alternative Medicine, 2008

Background: Yoga has been shown to be a simple and economical therapeutic modality that may be co... more Background: Yoga has been shown to be a simple and economical therapeutic modality that may be considered as a beneficial adjuvant for type 2 diabetes mellitus. This study investigated the impact of Hatha yoga and conventional physical training (PT) exercise regimens on biochemical, oxidative stress indicators and oxidant status in patients with type 2 diabetes. Methods: This prospective randomized study consisted of 77 type 2 diabetic patients in the Hatha yoga exercise group that were matched with a similar number of type 2 diabetic patients in the conventional PT exercise and control groups. Biochemical parameters such as fasting blood glucose (FBG), serum total cholesterol (TC), triglycerides, low-density lipoprotein (LDL), very low-density lipoproteins (VLDL) and high-density lipoprotein (HDL) were determined at baseline and at two consecutive three monthly intervals. The oxidative stress indicators (malondialdehyde-MDA, protein oxidation-POX, phospholipase A2-PLA2 activity) and oxidative status [superoxide dismutase (SOD) and catalase activities] were measured. Results: The concentrations of FBG in the Hatha yoga and conventional PT exercise groups after six months decreased by 29.48% and 27.43% respectively (P < 0.0001) and there was a significant reduction in serum TC in both groups (P < 0.0001). The concentrations of VLDL in the managed groups after six months differed significantly from baseline values (P = 0.036). Lipid peroxidation as indicated by MDA significantly decreased by 19.9% and 18.1% in the Hatha yoga and conventional PT exercise groups respectively (P < 0.0001); whilst the activity of SOD significantly increased by 24.08% and 20.18% respectively (P = 0.031). There was no significant difference in the baseline and 6 months activities of PLA2 and catalase after six months although the latter increased by 13.68% and 13.19% in the Hatha yoga and conventional PT exercise groups respectively (P = 0.144). Conclusion: The study demonstrate the efficacy of Hatha yoga exercise on fasting blood glucose, lipid profile, oxidative stress markers and antioxidant status in patients with type 2 diabetes and suggest that Hatha yoga exercise and conventional PT exercise may have therapeutic preventative and protective effects on diabetes mellitus by decreasing oxidative stress and improving antioxidant status.