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Biomedical subjects

C M Harper

Publications and source records attributed to C M Harper.

At least 37 records · Page 2Linked to original sources
PubMed2000

Recurrent intraneural ganglion cyst of the tibial nerve. Case report.

Different theories have evolved to explain the pathogenesis and the cell of origin of intraneural ganglion cysts. Reportedly only three cases of intraneural ganglion of the tibial nerve have been located within the popliteal fossa, and all of these were thought to arise within the nerve. The authors report a case of a recurrent tibial intraneural ganglion in which a connection to the proximal tibiofibular joint was demonstrated on magnetic resonance (MR) images and at surgery. Surgical ligation of the articular branch and evacuation of the cyst led to symptomatic relief, and an MR image obtained 1 year after surgery documented no recurrence. This case reinforces the fact that surgeons need to consider and search for an articular connection in all cases of intraneural ganglia, especially in those that have recurred.

Adult↗
PubMed1999

Myasthenia, thymoma, presynaptic antibodies, and a continuum of neuromuscular hyperexcitability.

BACKGROUND: Autoantibodies specific for the nicotinic acetylcholine receptor (AChR) of skeletal muscle impair neuromuscular transmission in myasthenia gravis (MG). Autoantibodies specific for alpha3 neuronal AChRs or voltage-gated potassium channels have been reported in patients with Isaacs syndrome, an acquired disorder of continuous muscle fiber activity characterized by neuromyotonia. OBJECTIVE: To report the neuromuscular autoantibody profiles of three patients with a syndrome of MG and neuromuscular hyperexcitability. RESULTS: All three patients reported here had clinical and electrophysiologic evidence of MG and neuromuscular hyperexcitability. None had neuromyotonia. Thymoma was proven in two patients and suspected in the third. One had MG and thymoma and subsequently developed cramp-fasciculation syndrome; MG and rippling muscle syndrome appeared simultaneously in the other two. All patients had muscle and neuronal AChR binding antibodies and striational antibodies. Only one had antibodies reactive with alpha-dendrotoxin-complexed potassium channels. CONCLUSIONS: The coexistence of cramp-fasciculation syndrome and acquired rippling muscle syndrome with MG, thymoma, and neuronal AChR autoantibodies suggests that there is a continuum of autoimmune neuromuscular hyperexcitability disorders related pathogenically to Isaacs syndrome. Manifestations of neuromuscular hyperexcitability may be altered and less apparent in the context of MG because of the coexisting defect of neuromuscular transmission.

Adult↗
PubMed1999

Guamanian neurodegenerative disease: electrophysiologic findings.

Amyotrophic lateral sclerosis (ALS), parkinsonism and/or dementia are highly prevalent among the Chamorro population of Guam. The incidence of Guamanian ALS has markedly declined in recent years, but these incidence figures may reflect underascertainment of subclinical disease. Guamanian Chamorro patients have not been systematically studied using modern clinical neurophysiological techniques. Electromyography (EMG: needle exam and nerve conduction studies) was used to study 29 patients with the major subtypes of Guamanian neurodegenerative disease, as well as 11 neurologically normal Guamanian Chamorro subjects. Central conduction was assessed by somatosensory evoked potentials (SEP's) in 16 patients. EMG evidence of peripheral neuropathy, (often subclinical) was found in 45% of Guamanian patients but no Chamorro control subjects. Diabetes mellitus, which is highly prevalent in this population, was present in some, but not all of these cases. Clinically unsuspected motor neuron disease was identified by EMG in only one of the 23 Guamanian patients with parkinsonism and/or dementia and in none of the 11 Chamorro control subjects. Two of seven patients with the clinical phenotype of Guamanian ALS had a more benign EMG pattern on the needle electrode exam with absence of fibrillation and fasciculation potentials. Three of 16 patients (all with parkinsonism and dementia) had mildly abnormal tibial SEP's. No patient had EMG evidence of myopathy or a defect of neuromuscular transmission. We conclude: (1) peripheral neuropathy may be a manifestation of Guamanian neurodegenerative disease; (2) the declining prevalence of ALS on Guam is not associated with the development of a subclinical form of motor neuron disease; (3) the substantial overlap of Guamanian ALS with parkinsonism-dementia reported in prior decades is no longer apparent; (4) abnormal central conduction, as assessed by tibial SEP's, is present in some patients with Guamanian parkinsonism-dementia.

Adult↗
PubMed1999

Ulnar neuropathy in surgical patients.

BACKGROUND: The goal of this project was to study the frequency and natural history of perioperative ulnar neuropathy. METHODS: A prospective evaluation of ulnar neuropathy in 1,502 adult patients undergoing noncardiac surgical procedures was performed. Patients were assessed with a standard questionnaire and neurologic examination before surgery, daily during hospitalization in the first week after surgery, and by telephone if they were discharged before 1 postoperative week. Patients in whom ulnar neuropathy developed were followed for 2 yr. RESULTS: Ulnar neuropathy developed in seven patients (0.5%; 95% confidence interval, 0.2% to 1.0%). Six of the seven patients were men. Symptoms of ulnar neuropathy began 2-7 days after surgery. Manifestations were mild and confined to sensory deficits in six patients. Symptoms resolved in four patients within 6 weeks. The remaining three patients had residual symptoms 2 yr later. CONCLUSIONS: In this surgical population, ulnar neuropathy was an infrequent complication. It occurred primarily in men who were 50-75 yr old and was not symptomatic until several days after surgery. Gender-dependent differences in the anatomy of the ulnar nerve and related structures at the elbow may serve as risk factors for ulnar neuropathy in patients having surgery.

Aged↗
PubMed1999

Lipoxygenase products increase monocyte adhesion to human aortic endothelial cells.

The development of atherosclerosis is accelerated in individuals with type 2 diabetes. Adhesion of monocytes to the vascular endothelium is a key initial step in atherogenesis. We have previously shown that monocyte adhesion to human aortic endothelial cells (HAECs) cultured long-term in high-glucose medium (25 mmol/L, 2 passages) is increased compared with cells grown in normal glucose (5 mmol/L). One potential mechanism for increased monocyte adhesion to HAECs under hyperglycemic conditions is via the 12-lipoxygenase (12-LO) pathway. In this study, we demonstrated in HAECs that the major LO metabolite of arachidonic acid was the 12-LO product, 12(S)-hydroxyeicosatetraenoic acid [12(S)-HETE], which was increased severalfold in HAECs cultured under high-glucose conditions. Furthermore, treatment of HAECs with 12(S)-HETE induced monocyte, but not neutrophil, adhesion an average of 3-fold (range of 1.5- to 5-fold) compared with untreated cells (75+/-5 versus 26+/-1 monocytes per field, respectively, P<0.001). Expression of the adhesion molecules vascular cell adhesion molecule-1, E-selectin, and intercellular adhesion molecule-1 was not significantly increased. However, both glucose and 12(S)-HETE induced a 60% increase in HAEC surface expression of connecting segment-1 (ie, CS-1) fibronectin, a ligand for very late-acting antigen-4 (VLA-4). The antibodies used to block monocyte integrin VLA-4 and leukocyte function-related antigen-1, a monocytic counterreceptor for intercellular adhesion molecule-1, inhibited the ability of both 12-LO products and high glucose to induce monocyte adhesion. These results definitively demonstrate for the first time in HAECs that the 12-LO pathway can induce monocyte-endothelial cell interaction and that the effects of glucose may be mediated, at least in part, through this pathway. Thus, these results suggest that the 12-LO pathway may play a role in the increased susceptibility of diabetics to atherosclerosis.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1998

Quinidine sulfate therapy for the slow-channel congenital myasthenic syndrome.

The slow-channel congenital myasthenic syndrome (SCCMS) is caused by gain of function mutations in subunits of the end-plate acetylcholine receptor (AChR). The mutations prolong the opening episodes of the AChR channel, leading to a depolarization block and an end-plate myopathy. Because levels of quinidine sulfate attainable in clinical practice shorten the opening episodes of genetically engineered mutant SCCMS receptors in vitro, we tested the notion that the drug can be of benefit in SCCMS. We treated 6 SCCMS patients with quinidine sulfate in an open-label trial, using objective clinical measures of muscle strength and repetitive stimulation studies as end points. One patient became allergic to quinidine after 7 days. The remaining patients tolerated the drug well and after 30 days of continuous therapy showed statistically significant improvement in muscle strength and in decrement of the compound muscle action potential elicited by rapid rates of stimulation.

Action Potentials↗
PubMed1998

Clinical and electrophysiologic attributes as predictors of results of autonomic function tests.

Autonomic dysfunction is a feature of some neuropathies and not others. It has been suggested that some clinical and electrophysiologic attributes are predictable of autonomic impairment detected using laboratory testing; however, dear guidelines are unavailable. We evaluated 138 relatively unselected patients with peripheral neuropathy who underwent neurologic evaluation, electromyography (EMG), nerve conduction studies, and autonomic function tests to determine which variables were predictive of laboratory findings of autonomic failure. The variables evaluated were 1) clinical somatic neuropathic findings, 2) clinical autonomic symptoms, and 3) electrophysiologic findings. Autonomic symptoms were strongly predictive (Rs = 0.40, p < 0.001) of autonomic failure. Among the non-autonomic indices, absent ankle reflexes were mildly predictive (Rs = 0.19, p = 0.022) of autonomic impairment, but all others were not (duration, clinical pattern, severity, weakness, sensory loss). Electrophysiologic changes of an axonal neuropathy predicted autonomic impairment while demyelinating neuropathy did not. We conclude that autonomic studies will most likely be abnormal in patients who have symptoms of autonomic involvement and those who have an axonal neuropathy.

Autonomic Nervous System Diseases↗
PubMed1998

Melanocortin mediated inhibition of feeding behavior in rats.

Melanocortinergic neurons are believed to play a role in the control of food intake. Melanocortin receptor agonists and antagonists modulate feeding in several mouse models of chemically and genetically induced hyperphagia. To date, little information is available describing the role of this neurological system in the control of the natural feeding cycle in genetically intact rats. To evaluate the involvement of melanocortins in spontaneous nocturnal feeding, the synthetic melanocortin receptor agonist, MTII and the antagonist, SHU9119 were administered ICV (third ventricle) alone and in combination. Dose-dependent inhibition or stimulation of food intake was observed with MTII or SHU9119, respectively. Co-injections containing equal concentrations of MTII and SHU9119 resulted in food intake that was indistinguishable from controls. Food intake patterns observed in studies in which various dose combinations of MTII and SHU9119 were co-injected are consistent with the concept that both affect feeding by acting on similar melanocortin receptors. The hypothesis that effects of melanocortins on feeding may be mediated via an NPY related pathway was tested by co-injecting MTII and NPY in a 2-h satiated food intake paradigm. MTII inhibited food intake induced by 5.0 microg hNPY in a dose dependent manner with the highest dose tested abolishing the NPY feeding response. The studies suggest that melanocortins act via specific receptors to control food intake in rats, possibly via an NPY related pathway. If similar neurochemical processes operate in humans, selectively modulating specific melanocortin receptor signaling may be an approach to the treatment of human obesity.

Animals↗
PubMed1998

Facial nerve electromyography and other cranial nerve monitoring.

Cranial nerves can be damaged during a variety of surgical procedures. The function of the cranial nerves can be monitored during surgery with electromyography (EMG), compound nerve and muscle action potentials (MAP), and auditory evoked potentials (AEP). We report important technical considerations that allow reliable recordings of these modalities during surgery, the criteria for determining a significant change in these electrophysiologic measures of function, the application of these techniques to specific surgical procedures, and the data that support the utility of cranial nerve monitoring.

Cranial Nerve Injuries↗
PubMed1997

Reversible MRI findings in a patient with Hashimoto's encephalopathy.

Diffuse subcortical MRI signal abnormalities were seen during a subacute exacerbation in a patient with Hashimoto's encephalopathy. The patient had an excellent clinical response to corticosteroids. Clinical recovery paralleled normalization of MRI abnormalities and lowering of thyroid microsomal antibody titer.

Aged↗
PubMed1996

MELAS- and Kearns-Sayre-type co-mutation [corrected] with myopathy and autoimmune polyendocrinopathy.

A 35-year-old woman with features of Kearns-Sayre syndrome consisting of progressive ptosis, ophthalmoparesis, mitochondrial myopathy, and pigmentary retinopathy also had autoimmune polyglandular syndrome type 11 (Addison's disease, autoimmune insulin-dependent diabetes mellitus, Hashimoto's thyroiditis, and primary ovarian failure). There was no history of similarly affected relatives. Analysis of muscle mitochondrial DNA (mtDNA) revealed a 2,532-bp deletion of the type seen in Kearns-Sayre syndrome as well as a heteroplasmic A3243G mutation in the tRNA-Leu(UUR) gene of the type seen in mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS). The patient's blood and her mother's blood harbored the A3243G mutation but not the deletion, and the maternal grandmother's blood had neither mutation. In muscle, the species of mtDNA harboring the deletion was exclusively associated with the species harboring the A3243G mutation, suggesting that the point mutation predisposed to the large-scale deletion. The mtDNA species with both mutations accounted for 88% of total muscle mtDNA. Other and as yet unrecognized point mutations in mtDNA might also be associated with, and possible causally related to, large-scale mtDNA deletions.

Adult↗
PubMed1996

Far-field auditory brainstem response in neurotologic surgery.

This is a review of our experience using far-field auditory brainstem monitoring during acoustic neuroma removal. The observations are based on 144 consecutive cases beginning in 1986. The factors of importance are tumor size, preoperative auditory function, and the preoperative presence of a wave V on the auditory brainstem response. Our experience suggests that preservation of hearing in tumors > 2.5 cm is rare. It was observed that preserving wave V does not guarantee preservation of hearing. Conversely, loss of wave V does not preclude preservation of hearing. It has also been noted that the presence of only wave I preoperatively does offer some hope that hearing can be preserved postoperatively. Finally, postoperative hearing function is usually equal to or worse than the preoperative function. Only rarely does the postoperative function improve.

Adolescent↗
PubMed1995

Pristane-induced effects on cytochrome P-4501A, ornithine decarboxylase and putrescine in rats.

The effects of pristane (2,6,10,14-tetramethylpentadecane) on cytochrome P-4501A (cP4501A) activity in microsomes, as well as on ornithine decarboxylase (ODC) activity and concomitant putrescine levels were examined in Copenhagen rats. In general, pristane treatment led to increased cP4501A levels when compared to basal levels, while co-treatment with 3-methylcholanthrene (3-MC) and pristane elicited augmented cP4501A responses when compared to responses induced by 3-MC alone. Increases in both ODC activity and putrescine levels were also observed in pristane treated rats. Collectively, these results indicate that pristane influences cP4501A activity and elicits promoter-like responses as reflected in elevated ODC activity and increased amount of putrescine.

Animals↗
PubMed1995

Treatment of stable chronic demyelinating polyneuropathy with 3,4-diaminopyridine.

OBJECTIVE: To determine whether 3,4-diaminopyridine (3,4-DAP) would improve clinical or electrophysiologic function in patients with stable chronic demyelinating polyneuropathy. DESIGN: We conducted a prospective, randomized, placebo-controlled, blinded, crossover study of 3,4-DAP in 34 patients with demyelinating polyneuropathy. MATERIAL AND METHODS: Of the 17 men and 17 women, who were 21 to 80 years of age, 27 had hereditary motor and sensory neuropathy type I and 7 had acquired demyelinating polyneuropathy. Treatment consisted of stepped doses of 3,4-DAP (increasing to 20 mg four times daily) or placebo for 4 days. Pretreatment and posttreatment determination of the Neurologic Disability Score (NDS); isometric muscle strength testing; median, ulnar, and peroneal nerve conduction studies; and measurement of serum 3,4-DAP were performed. Quantitative computer-assisted sensory examinations were done in five patients. RESULTS: The results for the final day of treatment with 3,4-DAP or placebo and the differences between pretreatment and posttreatment findings for total NDS, sensory NDS, isometric muscle strength testing, compound muscle action potential amplitude, sensory nerve action potential amplitude, motor and sensory conduction velocities, and vibration and cold detection thresholds did not vary significantly. A small improvement of 4 points in the motor NDS (P < 0.05) was found. Five patients with electrophysiologic conduction block had no significant reduction in the degree of block. CONCLUSION: Because no improvement was noted in most measurements of neurologic function, despite use of high doses of drug, 3,4-DAP is unlikely to be beneficial in the treatment of stable chronic demyelinating polyneuropathy.

4-Aminopyridine↗
PubMed1994

Recipient mononuclear cell recognition and adhesion to graft endothelium after human cardiac transplantation. Lymphocyte recognition leads to monocyte adhesion.

Transendothelial migration of mononuclear cells is crucial in the development of allograft rejection and transplant coronary disease. Adhesion of circulating cells to endothelium is the initial step in transendothelial migration. Human aortic endothelial cell cultures were established from aortic tissue harvested at the time of organ donation for cardiac transplantation which allowed specific recipient mononuclear cell-graft endothelial interactions to be studied. Confluent untreated endothelial cells were incubated with recipient mononuclear cells for 15 min to assess adhesion. Adhesion of recipient mononuclear cells to endothelium derived from their graft was threefold higher than adhesion to nonspecific endothelium (93 +/- 20 vs. 30 +/- 11 cells/high power field, P < 0.005). Graft-specific adhesion was inhibited by preincubation of the endothelium with antibodies to class I HLA (34 +/- 16 cells/high power field, P < 0.005). Immunofluorescence performed after adhesion showed that 73 +/- 6% of both specific and nonspecific adherent cells were monocytes. The use of purified lymphocyte and monocyte preparations showed that graft-specific lymphocytes induce unrelated monocytes to become adherent. These results suggest that lymphocytes are primed in vivo to recognize endothelium derived from their graft which leads to a rapid increase in lymphocyte and monocyte adhesion. Such allo-recognition may involve endothelial class I HLA molecules.

CD3 Complex↗