Biomedical subjects

Ian Hsiao

Publications and source records attributed to Ian Hsiao.

7 recordsLinked to original sources

PubMed2006

Re-growth of catecholaminergic fibers and protection of cholinergic spinal cord neurons in spinal repaired rats.

The extent of re-growth of catecholaminergic fibers, the survival of cholinergic neurons and the degree of autonomic dysreflexia were assessed in complete spinal cord-transected adult rats that received a repair treatment of peripheral nerve grafts and acidic fibroblast growth factor (aFGF). The rats were randomly divided into three groups: (1) sham control group (laminectomy only); (2) spinal cord transection at T8 (transected group); and (3) spinal cord transection at T8, followed by aFGF treatment and peripheral nerve graft (repaired group). The spinal cords and brains of all rats were collected at 6 months post-surgery. Immunohistochemistry for tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DBH), and fluoro-gold (FG) retrograde tracing were used to evaluate axon growth across the damage site, and immunocytochemistry for choline acetyl transferase (ChAT) was used to evaluate cholinergic neuronal cell survival following the injury and treatment. When comparing with the transected group, the repaired group showed: (1) lower elevation of mean arterial pressure during colorectal distension; (2) retrogradely labeled neurons in the hypothalamus, zona incerta, subcoeruleus nuclei and rostral ventrolateral medulla following application of FG below the repair site; (3) the presence of TH- and DBH-labeled axons below the lesion site; (4) higher numbers of ChAT-positive neurons in ventral horn and intermediolateral column near the lesion site. We conclude that peripheral nerve graft and aFGF treatments facilitate the re-growth of catecholaminergic fibers, also protect sympathetic preganglionic neurons and spinal motor neurons, and reduce autonomic dysfunction in a T-8 spinal cord-transected rat model.

Acetylcholine↗

PubMed2005

Modulation of cardiovascular excitatory responses in rats by transcutaneous magnetic stimulation: role of the spinal cord.

This study investigated the efficacy of magnetic stimulation on the reflex cardiovascular responses induced by gastric distension in anesthetized rats and compared these responses to those influenced by electroacupuncture (EA). Unilateral magnetic stimulation (30% intensity, 2 Hz) at the Jianshi-Neiguan acupoints (pericardial meridian, P 5-6) overlying the median nerve on the forelimb for 24 min significantly decreased the reflex pressor response by 32%. This effect was noticeable by 20 min of magnetic stimulation and continued for 24 min. Median nerve denervation abolished the inhibitory effect of magnetic stimulation, indicating the importance of somatic afferent input. Unilateral EA (0.3-0.5 mA, 2 Hz) at P 5-6 using similar durations of stimulation similarly inhibited the response (35%). The inhibitory effects of EA occurred earlier and were marginally longer (20 min) than magnetic stimulation. Magnetic stimulation at Guangming-Xuanzhong acupoints (gallbladder meridian, GB 37-39) overlying the superficial peroneal nerve on the hindlimb did not attenuate the reflex. Intravenous naloxone immediately after termination of magnetic stimulation reversed inhibition of the cardiovascular reflex, suggesting involvement of the opioid system. Also, intrathecal injection of delta- and kappa-opioid receptors antagonists, ICI174,864 (n=7) and nor-binaltorphimine (n=6) immediately after termination of magnetic stimulation reversed inhibition of the cardiovascular reflex. In contrast, the mu-opioid antagonist CTOP (n=7) failed to alter the cardiovascular reflex. The endogenous neurotransmitters for delta- and kappa-opioid receptors, enkephalins and dynorphin but not beta-endorphin, therefore appear to play significant roles in the spinal cord in mediating magnetic stimulation-induced modulation of cardiovascular reflex responses.

Afferent Pathways↗

PubMed2004

Functional magnetic ventilation in dogs.

OBJECTIVE: To investigate the efficacy of the magnetic stimulation of inspiratory muscles as an alternative to mechanical ventilation and functional electric stimulation. DESIGN: A prospective before-after trial. SETTING: Functional magnetic stimulation laboratory in a Veterans Administration health care system. ANIMALS: Six male mongrel dogs, each weighing between 25 and 35 kg. INTERVENTIONS: Commercially available magnetic stimulators with a round magnetic coil were used. The center of the magnetic coil was placed posteriorly over the C5-7 vertebrae of the spinal cord transected dogs. Magnetic stimulation parameters were set at 80% intensity, 20 Hz, and a 1.2-second on and 3.8-second off pulse train. MAIN OUTCOME MEASURES: The major outcomes were changes in tidal volume (VT), tracheal pressure (Ptr), and arterial partial pressure of carbon dioxide (PaCO2) and oxygen sustained by magnetic stimulation over time. RESULTS: The average Vt and Ptr produced during functional magnetic ventilation (FMV) were.47+/-.07 L and -4.7+/-.51 cmH2O, respectively. Blood gas data showed that PaCO2 increased from a baseline of 33 to 75 mmHg, whereas pH decreased from 7.33 to 6.99 at the end of the 1-hour FMV period. CONCLUSIONS: FMV was achieved for 2 hours in dogs with C2 spinal cord transection. Additional refinements in magnetic stimulation are needed to improve ventilation in animals.

Analysis of Variance↗

PubMed2004

Motor recovery and anatomical evidence of axonal regrowth in spinal cord-repaired adult rats.

Behavioral assessments of hindlimb motor recovery and anatomical assessments of extended axons of long spinal tracts were conducted in adult rats following complete spinal cord transection. Rats were randomly divided into 3 groups: 1) sham control group (laminectomy only; n = 12); 2) transection-only group, spinal cord transection at T8 (n = 20); and 3) experimental treatment group, spinal cord transection at T8, with peripheral nerve grafts (PNG) and application of acidic fibroblast growth factor (aFGF) (n = 14). The locomotor behavior and stepping of all rats were analyzed over a 6-month survival time using the Basso, Beattie, Bresnahan (BBB) open field locomotor test and the contact placing test. Immunohistochemistry for serotonin (5-HT), anterograde tracing with biotinylated dextran amine (BDA), and retrograde tracing with fluoro-gold were used to evaluate the presence of axons below the damage site following treatment. When compared with the transection-only group, the nerve graft with the aFGF group showed 1) significant improvement in hindlimb locomotion and stepping, 2) the presence of 5-HT-labeled axons below the lesion site at lumbar cord level (these were interpreted as regenerated axons from the raphe nuclei), 3) the presence of anterograde BDA labeling of corticospinal tract axons at the graft site and below, and 4) fluoro-gold retrograde labeling of neuron populations in motor cortex and in red nucleus, reticulospinal nuclei, raphe nuclei, and vestibular nuclei. We conclude that peripheral nerve grafts and aFGF treatments facilitate the regrowth of the spinal axons and improve hindlimb function in a T-8 spinal cord-transected rat model.

Animals↗

PubMed2002

High intensity magnetic stimulation over the lumbosacral spine evokes antinociception in rats.

OBJECTIVES: High intensity magnetic stimulation (MS) applied over the skin can painlessly depolarize superficial and deep nerves and we aimed to evaluate the effectiveness of MS of spinal nerves in evoking a potent analgesic response. METHODS: The MS was administered to adult male Sprague-Dawley rats using a Cadwell MES-10 high-speed magnetic stimulator. A Peltier device and von Frey fibers were used to determine heat and mechanical nociceptive responses of the rats. RESULTS: A brief (5 min) course of MS over the rat's lumbosacral spine produced a long-lasting (30-40 min) and robust (80-90% maximum possible effect) hindpaw antinociceptive effect to both mechanical and heat stimuli. Spinal cord transected rats had intact hindpaw nociceptive withdrawal responses, but transection eliminated MS evoked antinociception, indicating a critical extrasegmental component in the mechanism of MS antinociceptive action. The opiate receptor antagonist naloxone (5 mg/kg, i.p.) completely blocked MS evoked antinociception, demonstrating an opioidergic mechanism for MS antinociception. The alpha(2) adrenoceptor antagonist atipamezole (5 mg/kg, i.p.) slightly reduced the MS antinociceptive response to heat and had no effect on MS antinociception for mechanical stimuli. CONCLUSIONS: These data indicate that MS can evoke a robust, long-lasting antinociceptive effect, which requires an intact supraspinal pathway and is opioidergic mediated.

Adrenergic alpha-Antagonists↗

PubMed2002

Functional magnetic stimulation facilitates gastric emptying.

OBJECTIVE: To evaluate the effect of functional magnetic stimulation (FMS) on gastric emptying in able-bodied and spinal cord injury (SCI) subjects. DESIGN: A prospective, nonrandomized clinical experiment. SETTING: SCI and disorder center in a Veterans Affairs medical facility. PARTICIPANTS: Five healthy, able-bodied subjects and 4 subjects with SCI. INTERVENTION: A commercially available magnetic stimulator was used; a round magnetic coil was placed along the T9 spinous process. The intensity of the magnetic stimulation was 60%, with a frequency of 20 Hz, and a burst length of 2 seconds for the gastric emptying protocol. Man Outcome Measures: Rate of gastric emptying and time required to reach gastric emptying half-time (GE(t1/2)) with and without FMS. Data fit into linear regression curve. RESULTS: Accelerated gastric emptying was achieved in both able-bodied and SCI subjects. The mean +/- standard error of mean of the GE(t1/2) at baseline and with FMS was 36+/-2.9 minutes and 33+/-3.1 minutes, respectively, for able-bodied subjects, and 84+/-11.1 minutes and 59+/-12.7 minutes, respectively, for SCI subjects. CONCLUSION: Gastric emptying was enhanced by FMS in able-bodied subjects and was greatly enhanced in SCI subjects. FMS can be a useful noninvasive therapeutic tool to facilitate gastric emptying in humans.

Adult↗

PubMed2002

Peripheral nerve grafts and aFGF restore partial hindlimb function in adult paraplegic rats.

The purpose of this study was to evaluate the degree of functional recovery in adult rats with completely transected spinal cord following experimental treatment regimens that include implantation of peripheral nerve segments and local application of acidic fibroblast growth factor (aFGF). Rats were randomly divided to five groups: (1) spinal cord transection, (2) spinal cord transection and aFGF treatment, (3) spinal cord transection and peripheral nerve grafts, (4) spinal cord transection, aFGF treatment, and peripheral nerve grafts, and (5) sham control (laminectomy only). The locomotor behavior of all rats was analyzed by the Basso, Beattie and Bresnahan (BBB) open field locomotor test over the six months survival time. Immunohistochemisty for neurofilament protein, and somatosensory (SSEP) and motor evoked potentials (MEP) were used to evaluate axon growth across the damage site following the different treatments. The results show four principal findings: (1) Only the combination of peripheral nerve grafts and aFGF treatment improved hindlimb locomotor function after spinal cord transection. (2) The SSEP and MEP demonstrated electrophysiological evidence of both sensory and motor information crossing the damaged site, but only in the combined nerve grafts and aFGF treatment rats. (3) Immunostaining demonstrated neurofilament positive axons extending through the graft area and into distal end of spinal cord, but only in the group with combined nerve grafts and aFGF treatment. (4) Retransection of group 4 rats eliminated the behavioral recovery, MEP, and SSEP responses, indicating that the improvement of hindlimb locomotor activity came from supraspinal control. These results demonstrate the ability of the repair strategy combining peripheral nerve grafts and aFGF treatment to facilitate the regeneration of spinal ascending and descending tracts and also recovery of motor behavior following spinal cord injury.

Animals↗