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Biomedical subjects

J Chu

Publications and source records attributed to J Chu.

177 records · Page 10Linked to original sources
PubMedDate not supplied

Gene exchange in a ground cricket hybrid zone.

The ground crickets Allonemobius fasciatus and A. socius (Orthoptera: Gryllidae) are sister species that form a mosaic hybrid zone in the eastern United States. The genetic structure of the hybrid zone has been studied extensively by the use of protein electrophoresis. Here, we report the discovery of several random amplification of polymorphic DNA (RAPD) markers that distinguish the two species, and we assess the congruence of RAPD markers and protein markers with regard to the identification of hybrids in mixed populations. Both sets of markers indicate that gene flow between A. fasciatus and A. socius is quite limited.

Animals↗
PubMedDate not supplied

The effect of collimator backscatter radiation on photon output of linear accelerators.

The field-size dependence of the photon output of linear accelerators in air has been attributed in part to changes in the amount of radiation backscattered from the collimator jaws into the dose monitor chamber. This possible effect was investigated for a variety of accelerators with energies from 4 to 15 MV by measuring the monitor unit rate (MU/min) for different collimator openings. This measurement was made without dose rate feedback control, i.e., with constant electron beam current in the accelerator. The monitor unit rate was independent of collimator setting for all machines tested. Hence, it is concluded that backscattered radiation from the collimator jaws into the dose monitor chamber does not contribute to the variation of output with field size.

Particle Accelerators↗
PubMedDate not supplied

Lumbosacral radiculopathic pain presenting as groin and scrotal pain: pain management with twitch-obtaining intramuscular stimulation. A case report and review of literature.

BACKGROUND: Chronic groin and scrotal pain is a common entity plaguing a significant population of young athletic individuals. Aside from urologic and visceral etiologies, there is a vast array of underlying musculoskeletal and spinal abnormalities that may be found in these individuals. FINDINGS: Presented is a patient found to have chronic, spine-related groin and scrotal pain diagnosed with lower lumbar discogenic disease by physical examination findings, imaging studies and multi-level chronic radiculopathy by electrodiagnostic studies who was treated with twitch-obtaining intramuscular stimulation (TOIMS). Symptoms of groin and scrotal pain abated with therapy. CONCLUSION: Twitch-obtaining intramuscular stimulation has a promising role in the treatment of groin and scrotal pain of radiculopathic origin.

Adult↗
PubMedDate not supplied

Twitch-obtaining intramuscular stimulation in reflex sympathetic dystrophy.

BACKGROUND: Reflex Sympathetic Dystrophy (RSD) remains a painful disease entity of undetermined etiology and variable response to therapy. FINDINGS: Presented is a patient with left leg early RSD and chronic musculoskeletal back pain who received automated and electrical twitch-obtaining intramuscular stimulation (ATOIMS & ETOIMS) treatments. Diagnosis combined clinical symptoms of pain and allodynia, signs of motor/trophic changes and electromyographic evidence of especially of left L5 root level irritation, with chronic bilateral, multiple level partial lumbosacral nerve root involvement. Signs and symptoms of early RSD resolved with therapy. CONCLUSIONS: ATOIMS-ETOIMS have a promising role in the treatment of early RSD associated with neuropathic pain resulting from spondylotic radiculopathy.

Electric Stimulation Therapy↗
PubMedDate not supplied

The muscle twitch in myofascial pain relief: effects of acupuncture and other needling methods.

Proposed is that needling methods such as acupuncture, primarily effect pain relief in myofascial pain through a local mechanism, elicitation of muscle twitches. Occasionally, diagnostic needling procedures such as electromyography (EMG) can relieve such pain through insertional intramuscular movements of the needle electrode. This results in stimulation of the motor end-plate zones (MEPZs), eliciting muscle twitches. As needle elicitation of muscle twitches is a common diagnostic technique to identify myofascial trigger points (MTrPs), muscle twitches elicited at such points may be therapeutic, not just diagnostic. Occasionally evoked small local muscle twitches are observed in pain relieving methods using needle penetration or manipulation, such as classical or electrical acupuncture and intramuscular stimulation (IMS). Twitch elicitation has been observed to be essential to obtain myofascial pain relief associated with the needling methods of automated and electrical twitch-obtaining intramuscular stimulation (ATOIMS and ETOIMS). These two methods facilitate the elicitation of larger force twitches by mechanical or electrical stimulation respectively at motor end-plate zones.

Acupuncture Therapy↗
PubMedDate not supplied

The efficacy of automated/electrical twitch obtaining intramuscular stimulation (atoims/etoims) for chronic pain control: evaluation with statistical process control methods.

INTRODUCTION: Automated and/or electrical twitch-obtaining intramuscular stimulation (ATOIMS & ETOIMS) evoke twitches at/or near motor end plate zones to relieve muscle pain. OBJECTIVES: To demonstrate that pain levels recorded daily by patients enable statistical process control (SPC) analysis of ATOIMS & ETOIMS effects over time. METHODS: Four chronic fibromyalgic patients received ATOIMS & ETOIMS treatments to bilateral C3-C8 and L3-S1 myotomes and recorded daily pain on a visual analogue scale. Mechanical stimulation with ATOIMS involved a custom device to insert, oscillate and retract a monopolar needle (MN) at 2 Hz x2s. ETOIMS involved manual insertion of the MN and stimulating with 5 Volts, 0.5 ms pulse duration at 2 Hz for 2s to multiple sites. Positive outcome measures include two pain scales reduction. RESULTS: Patient 1-4 had 89, 38, 40, 36 treatments during a follow-up time of 625, 1018, 378, 466 days with 5.4 +/- 3.7, 8.0 +/- 4.9, 4.2 +/- 2.4 and 4.6 +/- 2.7 days between treatments (DBT) during the first 6 months and 4.7 +/- 3.0, 21.8 +/- 15.6, 6.2 +/- 4.4 and 4.3 +/- 2.5 DBT respectively in the latter phase of the therapy. The average pain level (APL) in 1st week of treatment for patient 1-4 were 6.4 +/- 1.1, 3.7 +/- 1.1, 6.6 +/- 2.8 and 7.5 +/- 0.4 and in the last week of treatment were 4.5 +/- 0.4, 1.2 +/- 0.1, 4.2 +/- 1.0 and 4.7 +/- 0.7 respectively. APL correlated negatively with time during the first 6 months for patients 2-4 and also after 6 months for patients 4 & 1 who had unchanged and reduced DBT respectively. APL correlated positively with time for patient 2 with no correlation for patient 3 (both had increased DBT) after 6 months. CONCLUSIONS: Patients will chronically record their pain scales daily enabling analysis by SPC. ATOIMS & ETOIMS applied periodically can be helpful in relieving fibromyalgic pain.

Adult↗
PubMedDate not supplied

Skill and selection bias has least influence on motor unit action potential firing rate/frequency.

INTRODUCTION: Motor unit action potential (MUAP) rise time in quantitative electromyography (QEMG) using multi-MUAP analysis may influence neuromuscular disease diagnosis. OBJECTIVE: To demonstrate in QEMG that MUAP firing rate/frequency (FR) is the parameter least dependent on electrodiagnostician skill (EDXc) skill and selection bias. METHODS AND MATERIALS: During minimal contraction (< 6 MUAPs/4.8 s analysis period) of tibialis anterior, 20 MUAPs were selected for QEMG at each of the 3 insertion sites. There were three EDXcs (professor & two fellows), each an independent MUAP selector + EMG machine itself (EMGM), for a total of four independent MUAP selectors. EDXc and selector order variation at each site involved the following. At insertion site1, during EMG by EDXc 1, the MUAP selector order was EDXc 1, EMGM, EDXc 2 and EDXc 3. At the following two sites, the previous 1st selector was sequentially rotated to become the last selector during EMG by the subsequent EDXc. The protocol was repeated in two subjects. MUAP inclusion criteria by EDXcs was MUAP rise time < 1 ms by visual inspection and, by the EMGM, any and all MUAPs during the 4.8 s analysis period. RESULTS: The reproducibility of measurements between MUAP selectors for mean frequency was satisfactory (correlation coefficient for inter-EDXc was 0.57, and 0.66 between the most experienced EDXc and EMGM. Inter- EDXc correlation coefficient was poor for amplitude (0.10), duration (0.34), size index (0.35), phases (-0.13) and turns (-0.22). Of the MUAPs collected by EMGM, the mean amplitude was smaller and mean duration was longer than those collected by the other 3 selectors with no significant differences for the other parameters. CONCLUSIONS: FR was the only satisfactorily reproduced parameter from QEMG of MUAPs between selectors, and least dependent on skill and/or selection bias. From this, FR appears a relatively objective parameter, while other parameters appear unduly influenced by EDXc skill and/or MUAP selection bias.

Action Potentials↗
PubMedDate not supplied

Motor unit action potential (MUAP) parameters affected by editing duration cursors.

INTRODUCTION: Quantitative electromyography (QEMG) allows fast analysis of motor unit action potential (MUAP) parameters such as amplitude, duration, size index (SI), phases, turns and firing rate. When automated duration cursor placement is incorrect, the electrodiagnostician will manually edit this function potentially introducing bias to the final results. OBJECTIVE: To identify that (1) size index is the MUAP parameter least affected by manually editing duration cursors and (2) MUAP amplitude will influence the manual cursor correction rate. MATERIALS AND METHODS: Included were twenty-one consecutive patients who had QEMG with monopolar needle electrode for diagnostic evaluation of their myofascial pain symptoms. Evaluated for neck pain included 6 bilateral upper limb and cervical paraspinal muscles and for lower back pain were 5 bilateral lower limb and lower back muscles. Twenty MUAPs were recorded from each muscle and hardcopies of data obtained before and after manual edit. RESULTS: Of a total of 5360 MUAPs analyzed 1764 (33%) required manual editing of duration cursors. Cursor correction rate 120 MUAP s/individual muscle analyzed was also similar at 33+/-17%. Percentage change in duration more so than turns, before and after correction, was significantly larger than that of other parameters. No significant differences in percentage changes noted between SI and phases. CONCLUSIONS: SI and phases are least influenced by the manual correction of duration cursors since there is insubstantial amplitude and area at the tail-end of the MUAP.

Action Potentials↗
PubMedDate not supplied

Quantitative motor unit action potentials (QMUAP) in whiplash patients with neck and upper-limb pain.

INTRODUCTION: Needle EMG studies in patients with whiplash symptoms to document presence of neural injury, such as cervical radiculopathy, are not available. OBJECTIVE: To document presence of motor unit action potential (MUAP) parameter changes compatible with neurogenic involvement in symptomatic-limb muscles in whiplash induced acute and chronic pain states. DESIGN: Retrospective review. SETTING: Out patient quantitative electromyography (QEMG) laboratory. PARTICIPANTS: 72 consecutive patients (mean age 43.6 years) who underwent QEMG between 1/2001 - 12/2004 for electrodiagnosis of neck and upper-limb pain related to auto-accidents (mean symptom duration 15.3 months). INTERVENTIONS: QEMG with MUAP parameter analysis. MAIN OUTCOME MEASURES: Amplitude, duration, size-index (SI), percentage of polyphasic units and firing rate analysis in chosen bilateral muscles representing C3-C8 myotomes. RESULTS: No spontaneous activity noted in muscles examined. Without subsetting symptom duration, symptomatic-side: asymptomatic-side MUAP parameter comparison showed significant increase in MUAP frequency on the symptomatic-side C6-muscle (10.4 +/- 1.3 vs. 9.7 +/- 1.4, p = < 0.05), and C7 muscle (10.0 +/- 1.2 vs. 9.1 +/- 1.1, p < or = 0.01). The symptomatic-side C6-muscle also showed increased percentage of polyphasic-MUAPs (23.7 +/- 13.1 vs. 15.9 +/- 12.7, p < 0.001). Patients with acute symptom duration (< 6 months, mean duration 3.4 +/- 1.4 months, N=26), showed increased percentage of polyphasic MUAPs in the symptomatic-side C6-muscle (27.0 +/- 12.3% vs. asymptomatic 22.2 +/- 17.6%, p < or = 0.05). In patients with chronic symptom duration (> or =6 months, mean duration 22.0 +/- 17.9 months, N=46), symptomatic-side C6-muscle showed increased polyphasic MUAPs (22.2 +/- 13.2%) vs. asymptomatic (15.5 +/- 11.6%), p < or = 0.02, and higher firing rates (10.3 +/- 1.7 vs. 9.6 +/- 1.3 respectively, p < or = 0.003). CONCLUSIONS: QEMG changes suggest neural injury in symptomatic side C6 and C7 innervated muscles, even in the absence of spontaneous activity. In acute and chronic pain patients a higher percentage of polyphasic MUAPs is noted in the symptomatic side C6 muscle. In chronic pain patients higher MUAP frequencies are noted in the symptomatic side C6 muscle.

Action Potentials↗