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Biomedical subjects

C M Gregory

Publications and source records attributed to C M Gregory.

12 recordsLinked to original sources
PubMed2007

Resistance training and locomotor recovery after incomplete spinal cord injury: a case series.

STUDY DESIGN: Longitudinal intervention case series. OBJECTIVE: To determine if a 12-week resistance and plyometric training program results in improved muscle function and locomotor speed after incomplete spinal cord injury (SCI). SETTING: University research setting. METHODS: Three ambulatory individuals with chronic (18.7+/-2.2 months post injury) motor incomplete SCI completed 12 weeks of lower extremity resistance training combined with plyometric training (RPT). Muscle maximum cross-sectional area (max-CSA) of the knee extensor (KE) and plantar flexor (PF) muscle groups was determined using magnetic resonance imaging (MRI). In addition, peak isometric torque, time to peak torque (T (20-80)), torque developed within the initial 220 ms of contraction (torque(220)) and average rate of torque development (ARTD) were calculated as indices of muscle function. Maximal as well as self-selected gait speeds were determined pre- and post-RPT during which the spatio-temporal characteristics, kinematics and kinetics of gait were measured. RESULTS: RPT resulted in improved peak torque production in the KE (28.9+/-4.4%) and PF (35.0+/-9.1%) muscle groups, as well as a decrease in T(20-80), an increased torque(220) and an increase ARTD in both muscle groups. In addition, an increase in self-selected (pre-RPT=0.77 m/s; post-RPT=1.03 m/s) and maximum (pre-RPT=1.08 m/s; post-RPT=1.47 m/s) gait speed was realized. Increased gait speeds were accompanied by bilateral increases in propulsion and hip excursion as well as increased lower extremity joint powers. CONCLUSIONS: The combination of lower extremity RPT can attenuate existing neuromuscular impairments and improve gait speed in persons after incomplete SCI.

Adolescent↗
PubMed2005

Lower extremity skeletal muscle function in persons with incomplete spinal cord injury.

STUDY DESIGN: A cross-sectional study design. OBJECTIVES: To characterize and specifically quantify impairments in muscle function after chronic incomplete spinal cord injury (SCI). SETTING: University of Florida, Gainesville, FL, USA. METHODS: Voluntary and electrically elicited contractile measurements were performed and voluntary activation deficits were quantitatively determined in the knee extensor and ankle plantar flexor muscle groups in 10 individuals with chronic incomplete SCI (C5-T8, ASIA C or D) and age-, gender-, height- and body weight matched healthy controls. RESULTS: Persons with incomplete-SCI were able to produce only 36 and 24% of the knee extensor torque and 38 and 26% of the plantar flexor torque generated by noninjured controls in the self-reported less-involved and more-involved limbs, respectively (P<0.05). In addition, both indices of explosive or instantaneous muscle strength, torque200 (absolute torque reached at 200 ms) and the average rate of torque development (ARTD) were dramatically reduced in the ankle plantar flexor and knee extensor muscle groups in persons with incomplete-SCI. However, the deficit in instantaneous muscle strength was most pronounced in the ankle plantar flexor muscles, with an 11.7-fold difference between the torque200 measured in the self-reported more involved limb and a 5-fold difference in the less-involved limb compared to control muscles. Voluntary activation deficits ranged between 42 and 66% in both muscle groups. Interestingly, electrically elicited contractile properties did not differ between the groups. CONCLUSION: The resultant impact of incomplete-SCI is that affected muscles not only become weak, but slow to develop voluntary torque. We speculate that the large deficit in torque200 and ARTD in the ankle plantar flexors muscles of persons with incomplete-SCI may limit locomotor function. The results presented in this study provide a quantitative and sensitive assessment of muscle function upon which future research examining rehabilitation programs aimed at restoring muscle function and promoting functional recovery after incomplete-SCI may be based.

Adult↗
PubMed2003

Effects of testosterone replacement therapy on skeletal muscle after spinal cord injury.

STUDY DESIGN: Randomized control. OBJECTIVE: To examine the effects of testosterone replacement therapy (TRT) on skeletal muscle 11 weeks after complete SCI. SETTING: Athens, Georgia USA. METHODS: Soleus (SOL), gastrocnemius (GA), tibialis anterior (TA), vastus lateralis (VL) and triceps brachii (TRI) muscles were taken from twelve young male Charles River rats 11 weeks after complete SCI (T-9 transection, n=8) or sham surgery (n=4). Rats received either TRT (two 5 cm capsules, n=4) or empty capsules (n=8) implanted at surgery. Muscle samples were sectioned and fibers analyzed qualitatively for myosin ATPase and quantitatively for succinate dehydrogenase (SDH), alpha-glycerol-phosphate dehydrogenase (GPDH) and actomyosin ATPase (qATPase) activities using standard techniques. RESULTS: SCI decreased average fiber size (49+/-4%) in affected muscles and the percentage of slow fibers in SOL (93+/-3% to 17+/-2%). In addition, there was a decrease in SDH and an increase in GPDH and qATPase activities across the four hind-limb muscles of the SCI animals. Fiber size in the TRI was increased (31+/-2%) by SCI while enzyme activities were not altered. Average fiber size across the four hind limb muscles was decreased by only 30% in TRT SCI animals and their SOL contained 39+/-2% slow fibers. TRT also attenuated changes in enzyme activities. There was no effect of TRT on the TRI relative to SCI. CONCLUSIONS: TRT was effective in attenuating alterations in myofibrillar proteins during 11 weeks of SCI in affected skelatal muscles. SPONSORSHIP: Supported by a grant from The National Institutes of Health (HD-33738) and HD-37645 to KV, and HD-39676 to GAD.

Analysis of Variance↗
PubMed2001

Metabolic enzymes and phenotypic expression among human locomotor muscles.

Percutaneous biopsies were taken from the right vastus lateralis (VL), tibialis anterior (TA), soleus (Sol), and lateral gastrocnemius (LG) muscles of eight recreationally active adult males. Approximately 60 fibers in each sample were analyzed for their type (I, IIa, or IIx), cross-sectional area (CSA), and succinic dehydrogenase (SDH), alpha glycerol phosphate dehydrogenase (GPDH) and calcium-activated actomyosin adenosine triphosphatase (qATPase) activities. This was done to test the hypothesis that metabolic enzyme activities are more reflective of the functional diversity among human locomotor muscles than fiber type composition. The results showed that enzymatic characteristics differed more or less than expected between muscles of the same or different fiber type. For example, the relative CSA occupied by fast fibers was only about 50% greater in the mixed (LG and VL) than in the slow (Sol and TA) muscles (57 vs. 38%). At the same time, average fiber SDH activity and fiber type specific SDH:qATPase*%CSA, both used as estimates of fatigue resistance, were greater in Sol and LG than in TA and VL. As a result, the two slow muscles and the two mixed muscles had different values, and a mixed muscle (LG) had higher values than a slow muscle (TA). The findings suggest that differences in enzymatic profile, more than fiber type composition, afford human locomotor muscles the capacity to perform their purportedly divergent functional tasks.

Energy Metabolism↗
PubMed1995

I should have been with Lisa as she died.

A mother's experience of the death of her 23-year-old daughter, who died in the Accident and Emergency (A & E) department where access to the resuscitation room (and her daughter) were denied to her. This mother was a senior nursing sister in another department at the same hospital, and she subsequently wrote an open letter to the A & E department, outlining her experience of this traumatic event. It was her hope that this information might help to improve the situation for other families, who might have similar desires and needs, but might not feel they had the right or maybe the articulation skills to express them. Nursing and medical management made the decision not to circulate this open letter to other professionals in the department.

Adult↗
PubMed1994

Computing for synchrotron radiation experiments.

Computing provision is of major concern to synchrotron radiation researchers. An overview is presented of the computing facilities for synchrotron radiation work at the Synchrotron Radiation Source, Daresbury Laboratory. Data acquisition, reduction and analysis are seen as an integrated activity essential for full utilization of beam time. We discuss the evolution of data-acquisition systems from stand-alone systems of limited computing power, to a unified project computing village using state-of-the-art equipment for combined-technique, high-data-rate experiments. A brief account of software packages for data reduction and analysis is also given.

Journal Article↗
PubMed1993

Histological examination of peroperative frozen sections in suspected lung cancer.

BACKGROUND: Despite extensive investigations some patients with suspected lung cancer may undergo thoracotomy without preoperative histological proof of malignancy. A questionnaire on the use of histological examination of peroperative frozen sections in such patients was sent to 50 thoracic surgeons. Replies were received from 41 surgeons and indicated an absence of consensus on the usefulness of histological examination of frozen sections in this context, confirming the need for this study. METHODS: During one year 60 consecutive patients undergoing thoracotomy for suspected lung cancer without a prior histological diagnosis were studied prospectively. At thoracotomy the surgeon assessed the lesion macroscopically and a verdict on whether it was malignant was recorded. A biopsy specimen was then taken for examination of a frozen section and the result recorded. The appropriate operation was performed and the surgeon's verdict and the report on the frozen section were compared with the definitive histological diagnosis based on a paraffin section. RESULTS: Of 50 malignant lesions, 43 were identified by the surgeon and 47 by examination of the frozen section (sensitivity 86% and 94% respectively). Of 10 benign lesions, four were identified by the surgeon and nine by examination of the frozen section (specificity 40% and 90% respectively). CONCLUSIONS: Clinical and macroscopic assessment at thoracotomy are inferior to examination of frozen sections in suspected lung cancer, particularly where the lesion is benign. Lung resection should not be performed without examination of peroperative frozen sections when thoracotomy is performed for suspected but unproved lung cancer.

Biopsy↗
PubMed1993

High and low affinity 5-HT2 and 5-HT1C binding sites: responses to neonatal 5,7-DHT lesions in rat brain.

5-HT receptor denervation supersensitivity has been proposed to explain behavioural supersensitivity to L-5-HTP in rats with 5,7-dihydroxytryptamine (5,7-DHT) lesions. No upregulation of 5-HT2 binding sites was found despite supersensitivity to putative 5-HT2,1C drugs. To test the hypothesis that the 5-HT1C properties of these drugs are involved instead, dose-response and time-course studies of 5-HT1C and 5-HT2 receptors were performed using several different radioligands in rat brain after making neonatal 5,7-DHT lesions by intraperitoneal injection. 5-HT1C sites labelled with [3H]-mesulergine showed a distinct regional distribution: brainstem > diencephalon > cortex > hippocampus > cerebellum, constituting 65, 70, 31, 70, and 73% of total sites labelled by [3H]-mesulergine in the absence of 20 nM spiperone to block 5-HT2 sites, respectively. 5,7-DHT lesions did not significantly alter BMAX, KD, or nH of [3H]-mesulergine-labelled 5-HT1C sites in cortex or other regions but did reduce the density of cortical [3H]-paroxetine sites (-55%). Cortical 5-HT1C sites labelled by [3H]-5-HT or [3H]-mianserin, and cortical 5-HT2 sites labelled by [3H]-DOB or [3H]-ketanserin, were also unaffected. These data suggest that although denervation supersensitivity of 5-HT1C or 5-HT2 receptors may occur at the level of the receptor transducer-effector, there is no evidence it occurs at the receptor recognition site.

5,7-Dihydroxytryptamine↗
PubMed1989

Effects of dantrolene sodium in rodent models of cardiac arrhythmia.

Dantrolene sodium has been compared with reference antiarrhythmic agents in rodent models of cardiac arrhythmia. In a coronary-artery-ligation model in rats, dantrolene sodium (3, 10 and 20 mg/kg i.v.) significantly decreased extrasystoles, episodes of ventricular tachyarrhythmia, and frequency, duration, and total episodes of ventricular fibrillation in a dose-dependent manner. In an electrically induced fibrillation model in rats, dantrolene sodium (10 and 20 mg/kg i.v.) significantly raised ventricular fibrillation threshold in a dose- and time-dependent manner. In contrast to its activity in these models, dantrolene sodium was not active in two chemically induced models involving automaticity. Aconitine-induced arrhythmias in rats and mice and ouabain-induced arrhythmias in guinea pigs were not suppressed by i.v. (10 or 20 mg/kg) or i.p. (100-3000 mg/kg) doses of the drug. These results show that the antiarrhythmic potential of dantrolene sodium, predicted by in vitro Class III and Class IV electrophysiological effects, is expressed in whole animal models.

Action Potentials↗
PubMedDate not supplied

One-dimensional modelling of foulant reduction in a microflow, amperometric-sensor system.

This paper presents one-dimensional simulations of an experimental, amperometric sensor system designed to reduce fouling at the sensor surface. The effect exploited in this system depends on differences in the diffusion coefficients of the analytes and foulants. We describe this effect and present simulations of a typical analyte (H2O2) and foulant (bovine serum albumin). The simulations show effective reduction of foulants: the concentration at the sensor surface is more than five orders of magnitude smaller than in the sample, while concentration of analyte is only reduced by one order of magnitude, and so remains measurable. Thus in cases where the target species has a lower diffusivity than the foulant (for example ions in samples containing protein) this technique can be very effective in extending the maintenance interval or lifetime of a sensor and increasing its operational value. Using a calibration factor obtained from experiments to relate concentration to amperometric signal, we predict a signal strength from the simulations that is consistent with the experimental results. The peak signal is approximately 10(-7) Amps in both simulation and experiment, and the time taken to reach this peak value is within a factor of three.

Chemistry Techniques, Analytical↗