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Biomedical subjects

L R Robinson

Publications and source records attributed to L R Robinson.

At least 37 records · Page 2Linked to original sources
PubMed1997

Laryngeal electromyography for the diagnosis and management of swallowing disorders.

Laryngeal electromyography has proved useful for the evaluation of neurologic disorders of the larynx. The techniques for this procedure are also well suited to investigate disorders of the pharyngeal phase of swallowing. The responses from the thyroarytenoid muscles, the cricothyroid muscles, and the cricopharyngeus muscle can offer information to aid in the diagnosis, prognosis, and in some cases, treatment of dysphagia. A general review of electromyographic responses with sample tracings from the larynx are included in this article.

Deglutition↗
PubMed1996

ETS1 and ETS2 in p53 regulation: spatial separation of ETS binding sites (EBS) modulate protein: DNA interaction.

p53 is an extensively studied tumor suppressor gene implicated in the genesis of a large number of varied tumors. However, the pathways of regulation for the wild-type p53 gene and its product are as yet unknown. In situ hybridization analyses of ETS1 and ETS2 expression during mouse embryogenesis, have shown a pattern similar to that of p53 gene expression. Significantly, we have identified several ETS-binding sites (EBS) in the promoter regions of the human and mouse p53 genes. In the human promoter two of these EBS are present in the form of a palindrome, with the two EBS cores being separated by four nucleotides. This report shows that the EBS palindrome of the human p53 promoter has a high affinity for ETS1 and ETS2 and that such binding interaction intracellularly is able to activate the transcription of a CAT reporter gene by 5-10-fold using COS cells. To investigate whether the spacing between the two EBS cores influences the DNA binding activity, we synthesized oligonucleotides with increasing distances (4,12,16, and 20 bases respectively) between the two EBS cores of the palindrome. We observed an inverse correlation between an increasing distance in the two EBS cores of the palindrome and the ETS1 and ETS2 DNA binding activity respectively. Interestingly, optimal DNA binding activity was observed when the distance between the two EBS cores was four bases, identical to that which occurs in the natural promoter. Furthermore we show that the p53 mRNA is expressed at higher levels in NIH3T3 cells overexpressing ETS2 gene product, suggesting that the ETS2 transcription factor is a likely candidate for regulating the expression of p53 in vivo.

3T3 Cells↗
PubMed1994

M/RMS: an EMG method for quantifying upper motoneuron and functional weakness.

A new method for quantifying upper motoneuron (UMN) weakness using standard EMG equipment is presented and compared to the twitch occlusion method. Control subjects and patients with stroke, spinal cord injury (SCI), and peripheral nerve injury (PNI) were evaluated. Force, EMG, and twitch force from nerve electrical stimulation were recorded during isometric contractions of the biceps and triceps. Ratios of the elicited CMAP amplitude (M)/voluntary-root-mean-square EMG activity (RMS) and of the voluntary contraction twitch force (Ti)/the resting twitch force (Tmax) were the two measures of UMN weakness studied. Both ratios are linearly correlated with force for controls, log M/RMS (r = 0.96) and Ti/Tmax (r = 0.86). Log M/RMS ratio was abnormally high (> mean + 2 SD; i.e., > 1.09) for weak muscles affected by stroke and incomplete SCI, but was normal in muscles weakened by PNI. An elevated M/RMS ratio, may aid in quantification of deficient supraspinal activation from UMN or functional weakness.

Adult↗
PubMed1994

The quality of life after orthotopic liver transplantation: an analysis of 166 cases.

We surveyed by questionnaire 346 patients who underwent orthotopic liver transplantation to determine their postoperative status. One hundred sixty-six patients returned the questionnaires, which were administered at least 12 months after the transplants. Universally, the patients could perform necessary activities of daily living, but 36.7% noted some extremity weakness, 18.1% noted pain in an extremity, and 40.4% noted "arthritis." Of the respondents, 41.3% rode a bike often, 28.4% swam, and endurance improved from 43.9% severely affected to 8.0% severely affected. Posttransplant employment was related to marital status (3.18 times more likely to be employed if married); duration of liver disease with patients having the disease more than 2 years 3.22 times more likely to be employed. Patients without pain, weakness, or arthritis were 7.8 times more likely employed. The exact nature of the musculoskeletal complaints remains to be defined.

Activities of Daily Living↗
PubMed1994

Diabetes and diabetes risk factors in second- and third-generation Japanese Americans in Seattle, Washington.

In Seattle, Washington, the prevalence of diabetes was 20% in second-generation (Nisei) Japanese-American men and 16% in Nisei women 45-74 years old, while the prevalence of impaired glucose tolerance (IGT) was 36% in Nisei men and 40% in Nisei women. Hyperglycemia was less and duration of diabetes shorter in women. Related to diabetes and IGT in Nisei were higher fasting plasma insulin levels and central (visceral) adiposity. Prevalence of diabetes was low among the younger (34-53 years old) third-generation (Sansei) men and women. Among self-reported non-diabetic Sansei, however, prevalence of IGT was 19% in men and 29% in women, and IGT was associated with both increased fasting plasma insulin levels and more visceral fat, suggesting that many Sansei are at risk of future diabetes. An important lifestyle factor in the development of NIDD in Japanese Americans appeared to be dietary saturated (animal) fat. Another factor may be physical inactivity. In Japanese-American women, menopause also appeared to be an important risk factor. These risk factors may be related to fostering the accumulation of visceral fat and the development of insulin resistance. Five-year follow-up examinations performed in non-diabetic Nisei men and women have yielded additional information concerning the prognosis of IGT. Of those women who were IGT at baseline, 34% were diabetic at follow-up while 17% returned to normal. In men who had been IGT at baseline, 18% were diabetic at follow-up while 36% returned to normal. Over the 5-yr follow-up interval, proportionally more women progressed from normal to IGT (54%) then went from IGT to normal (17%). For men, roughly equal proportions went from normal to IGT (37%) as from IGT to normal (36%). It would therefore appear that greater proportions of Nisei women are progressing to IGT and to NIDD than are Nisei men. This observation may be related to the increased risk of developing central obesity and insulin resistance following menopause. Prevalence of cardiovascular disease (hypertension, peripheral vascular disease, and/or coronary heart disease) was increased in Japanese Americans with IGT and NIDD. Neuropathy and retinopathy were associated only with NIDD.

Adult↗
PubMed1994

Further studies on the electrodiagnosis of diabetic peripheral polyneuropathy using discriminant function analysis.

Discriminant function analysis can be useful when applied to multiple nerve conduction parameters for diabetic and nondiabetic subjects to reveal the essential dimension along which key neuropathic differences occur between these groups. In this study, 19 electrophysiologic parameters were used in a stepwise discriminant function analysis to reveal a highly significant dimension of intergroup differences between 67 diabetic and 75 normal adult Japanese-American males. The classification functions thereby derived are more sensitive and specific than those reported previously for this population. Furthermore, when 72 additional subjects with impaired glucose tolerance were examined, they showed considerable overlap with the normal and separation from the diabetic groups, respectively. Their intermediate position between normal and diabetics in the key discriminant dimension indicates that essential neuropathic change is, at most, incipient in this latter group.

Cross-Sectional Studies↗
PubMed1994

Comparative efficacy of sunscreen reapplication regimens in children exposed to ambient sunlight.

Undercompliance with sunscreen reapplication recommendations is a probable factor in suboptimal childhood ultraviolet radiation (UVR) protection. However, improving on the ability of sunscreens to absorb UVR without requiring frequent reapplication is difficult because the models most frequently used to develop and evaluate photoprotectants have only a limited ability to incorporate behavioral and environmental variables that are primarily responsible for loss of sunscreen efficacy. Hence, the objective of the present work was to develop a method to evaluate the efficacy of various regimens of sunscreen reapplication in children, under conditions of unrestricted behavior and exposure to ambient sunlight. Ninety-eight children, ages 7-12, Fitzpatrick skin types I-III, were divided between two study groups. The majority were types I-II, and all types were approximately equally represented between the groups. The children received single or multiple applications of a sun protection factor 25 sunscreen to preassigned lateral halves of the body and engaged in unrestricted activities throughout a 6- (group I) or 8-h (group II) period of sun exposure at a seaside location. The end measurement for these studies was incidence and severity of erythema 18 to 22 h after peak UV exposure. The results obtained showed that 1 or 4 sunscreen applications yielded comparable erythema protection after a 6-hour sun exposure, totaling 13 minimal erythema doses (MED). However, after an 8-h, 21 MED exposure, incidence and severity of erythema was greater at body sites treated with 1 compared with 5 sunscreen applications.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrylates↗
PubMed1994

Normal limits of side-to-side H-reflex amplitude variability.

Our hypothesis was that side-to-side difference in the tibial H-reflex amplitude can aid in the diagnosis of unilateral S1 radiculopathy with an otherwise normal side-to-side H-reflex latency difference. We studied 47 healthy subjects, (mean +/- SD, 35 +/- 10 years) using methods similar to those described by Braddom and Johnson. Only those with side-to-side latency difference less than 1.5 msec were included (n = 45). Current was increased in 0.5 to 1.0 mA increments until the H-reflex amplitude maximized and then fell; on each side the response with the maximal peak-to-peak amplitude was measured for peak-to-peak amplitude and onset latency. The amplitude on the side of the smaller response was expressed as a ratio of the contralateral amplitude; this mean value (+/- SD) was 0.74 +/- 0.17. We conclude that a side-to-side amplitude ratio smaller than 0.4 (mean - 2 SD) in the face of a normal side-to-side latency difference is probably abnormal.

Adult↗
PubMed1994

Electrodiagnosis of upper limb weakness in acute quadriplegia.

Clinical and neuropathologic observations after cervical spinal cord injury suggest varying involvement of gray and white matter. The resulting upper limb weakness may reflect varying degrees of upper motoneuron (UMN) and/or lower motoneuron (LMN) involvement. This study uses electrophysiologic measures, including compound muscle action potential (M response) amplitude, root mean square (RMS) of the surface electromyographic activity during voluntary muscle contractions and the firing rate of motor units, to distinguish UMN and LMN weakness in upper extremities after acute quadriplegia. M response amplitude did not correlate with strength; many muscles had large M responses given their strength. These muscles manifest: (1) high M/RMS ratios (ratio of electrically elicited to voluntarily recruited electromyographic activity) and (2) slow firing rates of single motor units during maximal isometric contractions. For muscles with normal M amplitudes, M/RMS ratio correlates inversely with strength. For muscles with normal M/RMS ratios, M amplitude correlates positively with strength. Cluster analysis was used to distinguish UMN, LMN or Mixed types of weakness. Distinguishing these different types of weakness in acute quadriplegia may allow individualized rehabilitation for the type of weakness present.

Action Potentials↗
PubMed1993

The efficacy of femoral nerve intraoperative somatosensory evoked potentials during surgical treatment of thoracolumbar fractures.

Somatosensory evoked potential (SEP) monitoring of thoracolumbar procedures typically includes posterior tibial and peroneal nerve recordings. The addition of femoral nerve SEP monitoring, however, should better predict the evolution of postoperative neurologic deficits affecting the midlumbar roots. To assess the value of intraoperative femoral SEPs, 26 cases of traumatic injury to the thoracolumbar spine between T12 and L4 were prospectively assessed. Twenty-four had clear femoral nerve responses bilaterally recorded from an epidural electrode. Five had significant intraoperative SEP changes: one had isolated femoral nerve changes, two had only peroneal or tibial nerve changes, and two had concomitant changes in both femoral and peroneal or tibial nerves. Loss of the femoral nerve response in one patient was correlated with marked postoperative knee extensor weakness, in spite of immediate action taken by the surgeon. The authors conclude that femoral nerve SEPs provide an effective tool to monitor the midlumbar roots intraoperatively.

Adult↗
PubMed1993

Deriving reference values in electrodiagnostic medicine.

Traditional methods for determining nerve conduction reference values have usually involved studying a group of normal controls, and determining the mean +/- 2 standard deviations (SD) for each parameter. Recent studies suggest other factors should be taken into account. Height has a greater effect on conduction velocity than age or temperature. The common assumption that conduction values follow a normal, bell-shaped Gaussian distribution appears unwarranted. The curve for some conduction parameters is significantly skewed, making a mean +/- 2 SD definition of normality inaccurate to a clinically important degree. In developing and using reference values one should consider height, age, and temperature, and calculate the mean +/- 2 SD of the transformed data to remove the effects of skew. Reference values provide only a guide to the probability a given result came from a healthy or diseased individual; one should therefore seek multiple internally consistent abnormalities before diagnosing disease on the basis of electroneurography.

Body Height↗
PubMed1993

Selective deep peroneal nerve injury associated with arthroscopic knee surgery.

We report 3 cases of isolated deep peroneal nerve injury as a complication of arthroscopic knee surgery. At the level of the knee joint, the deep and superficial peroneal nerves are usually joined as the common peroneal nerve. However, because of the fascicular structure, a partial nerve injury can result in an isolated injury to the deep peroneal nerve fibers. Due to the intraneural topography of the peroneal nerve, electrodiagnostic studies in a partial nerve injury may erroneously indicate a more distal lesion.

Action Potentials↗
PubMed1993

Silent periods after electromagnetic stimulation of the motor cortex.

Electromagnetic stimulation has been used to excite tracts in the human motor cortex, but little has been done to study inhibitory effects. In three normal subjects we have noted that an electromagnetic stimulation applied to the motor cortex during maximum voluntary contraction produces silent periods lasting up to 300 ms in the contralateral abductor pollicis brevis. Duration of the silent period is directly proportional to the intensity of the stimulus. Abductor hallucis has similar silent periods lasting 150 to 200 ms, although proximal upper and lower limb muscles have shorter silent periods. F and H waves are easily elicited during this silent period suggesting that the alpha motoneuron is still excitable. This silent period may result, at least in part, from a synchronous volley of inhibitory postsynaptic potentials induced by the electromagnetic stimulator at the cortical level. This technique may prove useful in further delineating cortical inhibitory function.

Adult↗
PubMed1993

Combined effects of compression and hypotension on nerve root function. A clinical case.

Previous animal experiments suggest that mild compression may increase susceptibility of nerve roots to the effects of hypotension. The authors report the case of a patient with an unstable L2 burst fracture whose motor skills and senses were intact. During fracture reduction and spinal distraction, sensory-evoked potentials were recorded from the epidural space after right and left femoral and tibial nerve stimulation. Induced hypotension was used during the surgery. All responses were normal at the outset of the surgery. With hypotension, a marked drop in the amplitude of the right femoral evoked potential amplitude occurred; left femoral and both tibial responses remained unchanged. Evoked potential changes were reversible with reversal of hypotension. Postoperatively, the patient was neurologically intact. Further analysis revealed a significant correlation between the right femoral evoked potential amplitude and systolic blood pressure (r = 0.63, P < 0.005), whereas amplitudes of the other responses were not significantly correlated with systolic blood pressure. This report provides clinical evidence to support the hypothesis that hypotension and local compression exert additive adverse effects on nerve root function.

Adult↗
PubMed1993

Correlation between stroboscopy and electromyography in laryngeal paralysis.

Twenty patients with vocal fold motion impairment were reviewed to correlate the findings of electromyography (EMG) and stroboscopy. The causes of motion impairment were idiopathic, previous surgery with recurrent laryngeal nerve injury, neck and skull base trauma, and neoplasm. The EMG studies were analyzed to assess the status of innervation of the immobile vocal fold. The presence or absence of the mucosal wave prior to therapeutic intervention was determined with stroboscopic examination. Eight of 10 patients with EMG evidence of reinnervation or partial denervation were found to have mucosal waves, and 3 of 10 patients with EMG evidence of denervation were found to have mucosal waves. Six patients developed mucosal waves after surgical medialization, despite evidence of denervation by EMG criteria. These findings support the premise that tension and subglottic pressure, rather than status of innervation, determine the presence of the mucosal wave.

Adult↗
PubMed1993

Incidence and natural history of phrenic neuropathy occurring during open heart surgery.

OBJECTIVE: To study the incidence of phrenic neuropathy following coronary artery bypass grafting and determine long-term outcome. DESIGN: Prospective observational. SETTING: Surgical ICU in a university hospital, out-patient follow-up. PATIENTS: Ninety-two consecutive patients undergoing open heart surgery. INTERVENTIONS: None. MEASUREMENTS: Chest radiographs (CXR) 48 to 72 h post-operatively, ultrasonography of diaphragm, phrenic nerve conduction studies, diaphragmatic electromyogram, each repeated every 1 to 3 months until normal. MAIN RESULTS: Seventy-eight of 92 (78 percent) patients had abnormal radiographs, 42 of 78 (54 percent) with abnormal CXRs had abnormal diaphragm motion, 24 of 42 (57 percent) with abnormal motion had phrenic neuropathy. Patients with normal diaphragm motion improved faster than those without; patients with normal nerve conduction (and abnormal motion) improved faster than those with abnormal nerve conduction. CONCLUSIONS: Phrenic neuropathy is relatively common if sensitive tests are utilized for diagnosis. Nerve conduction studies can predict duration of morbidity. Most patients have low morbidity and recover fully. Abnormal diaphragm motion alone is not diagnostic of phrenic nerve injury.

Aged↗