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Biomedical subjects

J D England

Publications and source records attributed to J D England.

At least 19 recordsLinked to original sources
PubMed2005

Distal symmetric polyneuropathy: a definition for clinical research: report of the American Academy of Neurology, the American Association of Electrodiagnostic Medicine, and the American Academy of Physical Medicine and Rehabilitation.

The objective of this report was to develop a case definition of distal symmetric polyneuropathy to standardize and facilitate clinical research and epidemiologic studies. A formalized consensus process was employed to reach agreement after a systematic review and classification of evidence from the literature. The literature indicates that symptoms alone have relatively poor diagnostic accuracy in predicting the presence of polyneuropathy; signs are better predictors of polyneuropathy than symptoms; and single abnormalities on examination are less sensitive than multiple abnormalities in predicting the presence of polyneuropathy. The combination of neuropathic symptoms, signs, and electrodiagnostic findings provides the most accurate diagnosis of distal symmetric polyneuropathy. A set of case definitions was rank ordered by likelihood of disease. The highest likelihood of polyneuropathy (useful for clinical trials) occurs with a combination of multiple symptoms, multiple signs, and abnormal electrodiagnostic studies. A modest likelihood of polyneuropathy (useful for field or epidemiologic studies) occurs with a combination of multiple symptoms and multiple signs when the results of electrodiagnostic studies are not available. A lower likelihood of polyneuropathy occurs when electrodiagnostic studies and signs are discordant. For research purposes, the best approach to defining distal symmetric polyneuropathy is a set of case definitions rank ordered by estimated likelihood of disease. The inclusion of this formalized case definition in clinical and epidemiologic research studies will ensure greater consistency of case selection.

Clinical Protocols↗
PubMed2005

Distal symmetrical polyneuropathy: definition for clinical research.

The objective of this report was to develop a case definition of "distal symmetrical polyneuropathy" to standardize and facilitate clinical research and epidemiological studies. A formalized consensus process was employed to reach agreement after a systematic review and classification of evidence from the literature. The literature indicates that symptoms alone have relatively poor diagnostic accuracy in predicting the presence of polyneuropathy; signs are better predictors of polyneuropathy than symptoms; and single abnormalities on examination are less sensitive than multiple abnormalities in predicting the presence of polyneuropathy. The combination of neuropathic symptoms, signs, and electrodiagnostic findings provides the most accurate diagnosis of distal symmetrical polyneuropathy. A set of case definitions was rank ordered by likelihood of disease. The highest likelihood of polyneuropathy (useful for clinical trials) occurs with a combination of multiple symptoms, multiple signs, and abnormal electrodiagnostic studies. A modest likelihood of polyneuropathy (useful for field or epidemiological studies) occurs with a combination of multiple symptoms and multiple signs when the results of electrodiagnostic studies are not available. A lower likelihood of polyneuropathy occurs when electrodiagnostic studies and signs are discordant. For research purposes, the best approach for defining distal symmetrical polyneuropathy is a set of case definitions rank ordered by estimated likelihood of disease. The inclusion of this formalized case definition in clinical and epidemiological research studies will ensure greater consistency of case selection.

Electrodiagnosis↗
PubMed2002

Accumulation of PN1 and PN3 sodium channels in painful human neuroma-evidence from immunocytochemistry.

BACKGROUND: The axolemmal distribution and density of voltage-gated sodium channels largely determines the electrical excitability of sprouting neurites. Recent evidence suggests that accumulation of sodium channels at injured axonal tips may be responsible for ectopic axonal hyperexcitability and the resulting abnormal sensory phenomena of pain and paresthesias. For future improvement in pain management it is necessary to identify structurally significant generators of autorhythmicity. A first step in this regard will be to determine the predominant types of sodium channels in injured axons. The opportunity to test human specimens from painful and non-painful neuroma is of great value. METHODS: We employed immunocytochemical methods to investigate if two types of highly specific voltage-gated sodium channel subtypes could be detected in sections of human neuroma. FINDINGS: Both subtypes of sodium channels PN1 and PN3 accumulated abnormally in human neuromas. The immunoreactive pattern was more pronounced in painful neuromas. This is in contrast to previous reports that focused either on PN1 or PN3 as main generators of hyperexcitability induced pain. INTERPRETATION: Both, PN1 and PN3 seem to be involved in hyperexcitability induced pain. It can be expected that a variety of other highly specific voltage gated sodium channel subtypes will be detected in regenerating peripheral nerve in the near future, which contribute to the development of neuropathic pain states. Thus, in order to therapeutically control hyperexcitability induced neuropathic pain, it might be worthwhile to develop pharmaceuticals that can selectively block different sodium channel subtypes and subunits.A review of the role of sodium channels in neuropathic pain is implemented in the discussion.

Humans↗
PubMed2000

A possible role for nerve growth factor in the augmentation of sodium channels in models of chronic pain.

Inflammation induces an upregulation of sodium channels in sensory neurons. This most likely occurs as a result of the retrograde transport of cytochemical mediators released during the inflammatory response. The purpose of this study was to determine the effect of the subcutaneous administration of one such mediator, nerve growth factor (NGF), on the production of sodium channels in neurons of the rat dorsal root ganglion. For this, hindpaw withdrawal from either a thermal or mechanical stimulus was measured in rats at selected intervals for up to 2 weeks following injections of NGF. Sodium channel augmentation was then examined in dorsal root ganglia using site-specific, anti-sodium channel antibodies. Both thermal and mechanical allodynia was observed between 3 and 12 h post-injection. The hyperalgesic response returned to baseline by approximately 24 h post-injection. Sodium channel labeling was found to increase dramatically in the small neurons of the associated dorsal root ganglia beginning at 23 h, reached maximum intensity by 1 week, and persisted for up to 3 months post-injection. Pre-blocking NGF with anti-NGF prevented the NGF-induced decrease in paw withdrawal latencies and significantly reduced the intensity of sodium channel labeling. The results indicate that NGF is an important mediator both in the development of acute hyperalgesia and in the stimulation of sodium channel production in dorsal root ganglia during inflammation.

Animals↗
PubMed2000

Unusual electrophysiological findings in X-linked dominant Charcot-Marie-Tooth disease.

X-linked Charcot-Marie-Tooth disease (CMTX) is the second most common form of Charcot-Marie-Tooth disease. Variable histopathological and nerve conduction velocity (NCV) results have suggested either a primary demyelinating or axonal polyneuropathy. We identified five individuals across three generations in a family with CMTX associated with a mutation in the gene coding for connexin 32. All individuals were studied by clinical neurological examination, DNA analysis, and nerve conduction studies. The proband (1174/KD) also underwent a sural nerve biopsy. As expected, all the affected males were more clinically affected than the females. All affected males and obligate female carriers exhibited some electrophysiological characteristics of demyelination. However, striking heterogeneity of nerve conduction velocities was seen. This family shows that CMTX is a heterogeneous and distinctly nonuniform demyelinating polyneuropathy, the severity of which varies with sex and age. Such electrophysiological variability is unique among hereditary neuropathies.

Charcot-Marie-Tooth Disease↗
PubMed2000

Long-term topical timolol and blood lipids: the Blue Mountains Eye Study.

OBJECTIVES: To examine whether an association exists between long-term use of topical timolol and blood lipids, including high-density lipoprotein cholesterol (HDL-C), cholesterol, and triglycerides, among participants of the Blue Mountains Eye Study. METHODS: From 1992 through 1994, a detailed medical and eye examination was performed in 3,654 people aged 49 years or older, representing 82% of permanent residents in two postcode areas west of Sydney. Glaucoma and ocular hypertension were diagnosed, and an ophthalmic history was taken, including use of topical timolol. Fasting blood tests were performed in 89% of subjects. Lipid levels were compared in subjects using topical timolol for at least 1 year with those not using timolol, after excluding people using oral beta-blockers, topical beta1-selective agents, or oral lipid-lowering medications. RESULTS: Analyses compared blood lipids of 63 people who had used topical timolol for at least 1 year with 2,597 nonusers. No statistically significant differences were found in any blood lipid mean levels between treated and untreated people, after multivariate adjustment. However, subgroup analyses of men and women separately showed that male timolol users had a mean value of HDL-C 0.13 mmol/L (11%) lower then the mean value of male nonusers, while female timolol users had a mean value of HDL-C 0.09 mmol/L (5%) higher than the mean for female nonusers. There were no statistically significant associations between timolol treatment duration and HDL-C or other lipid levels. Previously reported adverse effects of oral beta-blockers on blood lipid levels were confirmed. CONCLUSIONS: These population-based data suggest that long-term administration of topical timolol for glaucoma or ocular hypertension can cause adverse effects on HDL-C in men, but not in women. The magnitude of the effect in men was similar to that previously described in a number of short-term studies.

Adrenergic beta-Antagonists↗
PubMed2000

Use of GHb (HbA1c) in screening for undiagnosed diabetes in the U.S. population.

OBJECTIVE: To evaluate the use of GHb as a screening test for undiagnosed diabetes (fasting plasma glucose > or =7.0 mmol/l) in a representative sample of the U.S. population. RESEARCH DESIGN AND METHODS: The Third National Health and Nutrition Examination Survey included national samples of non-Hispanic whites, non-Hispanic blacks, and Mexican Americans aged > or =20 years. Of these subjects, 7,832 participated in a morning examination session, of which 1,273 were excluded because of a previous diagnosis of diabetes, missing data, or fasting time of <8 h before examination. Venous blood was obtained to measure fasting plasma glucose and GHb in the remaining 6,559 subjects. Receiver operating characteristic curve analysis was used to examine the sensitivity and specificity of GHb for detecting diabetes at increasing GHb cutoff levels. RESULTS: GHb demonstrated high sensitivity (83.4%) and specificity (84.4%) for detecting undiagnosed diabetes at a GHb cutoff of 1 SD above the normal mean. Moderate sensitivity (63.2%) and very high specificity (97.4%) were evident at a GHb cutoff of 2 SD above the normal mean. Sensitivity at this level ranged from 58.6% in the non-Hispanic white population to 83.6% in the Mexican-American population; specificity ranged from 93.0% in the nonHispanic black population to 98.3% in the non-Hispanic white population. CONCLUSIONS: GHb is a highly specific and convenient alternative to fasting plasma glucose for diabetes screening. A GHb value of 2 SD above the normal mean could identify a high proportion of individuals with undiagnosed diabetes who are at risk for developing diabetes complications.

Adult↗
PubMed1999

Development of inflammatory hypersensitivity and augmentation of sodium channels in rat dorsal root ganglia.

The development of thermal allodynia in relationship to sodium channel augmentation in dorsal root ganglia (DRGs) was studied in albino rats. Paw withdrawal latencies were measured hourly following complete Freund's adjuvant (CFA) injections. Sodium channels were demonstrated with immunocytochemistry. Sustained minimum latencies were attained between 10 and 12 h post-injection. Sodium channel labeling began to increase at 23 h post-injection and reached maximum levels by 24 h. Thermal hypersensitivity is thus established 12 h before sodium channel augmentation can be demonstrated.

Animals↗
PubMed1999

AAEM case report 33: costoclavicular mass syndrome. American Association of Electrodiagnostic Medicine.

A true costoclavicular mass syndrome associated with a brachial plexopathy is rare. We report the occurrence of a severe brachial plexopathy as a late complication of a displaced midclavicular fracture. An exuberant callus associated with the clavicular fracture acted as a mass lesion to compress the brachial plexus within the costoclavicular space (i.e., between the clavicle and the first rib). The clinical features and the electrodiagnostic findings in this patient were crucial in suggesting the diagnosis, which was subsequently confirmed by radiographic studies and surgical exploration. Surgical excision of the hyperabundant callus and freeing of the entrapped brachial plexus resulted in marked improvement of the patient's neurological symptoms. Recognition of this uncommon complication of a clavicular fracture is important for the timely diagnosis of this treatable problem.

Aged↗
PubMed1999

Entrapment neuropathies.

Entrapment neuropathies occur when nerves are chronically compressed or mechanically injured at specific locations. Some of these focal neuropathies such as carpal tunnel syndrome are common, and others such as neurogenic thoracic outlet syndrome are rare. This article highlights recent advances and interesting observations that cover a wide spectrum of such focal neuropathies. Selected disorders that can affect individual peripheral nerves and masquerade as 'entrapment neuropathies' are also emphasized.

Carpal Tunnel Syndrome↗
PubMed1998

Abnormal distributions of potassium channels in human neuromas.

Twenty-seven human traumatic neuromas were examined immunocytochemically using highly specific antibodies directed against the voltage-gated delayed-rectifier potassium channel, Kv1.1. Normal sural nerves from six of the above-noted patients served as control specimens. Additionally, nine of the neuromas and two of the sural nerves were immunostained for voltage-gated calcium channels using an antibody that reacts with a wide spectrum of calcium channels. Normal myelinated fibers showed Kv1.1 specific immunoreactivity only at the juxtaparanodal regions. In contrast, within the neuromas approximately 30% of the myelinated fibers exhibited Kv1.1 specific immunoreactivity in dense patches along internodal axonal regions. The clustering of Kv1.1 channels along myelin-ensheathed internodal segments of axon was highly specific for the neuromas, and was never seen in normal nerve. Specific calcium channel immunoreactivity was not detectable in either the neuromas or sural nerves. Taken together with prior studies on sodium channels, these results suggest that selective and specific mechanisms control the distribution of ion channels within neuromas. Further investigation of ion channel changes within neuromas should provide a better understanding of the abnormal axonal hyperexcitability that frequently develops after nerve injury.

Axons↗
PubMed1998

Rapid sodium channel augmentation in response to inflammation induced by complete Freund's adjuvant.

The mechanisms by which inflammation induces a chronic pain state are poorly understood. Following the induction of many painful conditions, an increase in the spontaneous firing rate of neurons is often observed in peripheral sensory ganglia. Since ion channels are essential mediators of spike generation and impulse conduction, it is reasonable to postulate that local changes in ion channel expression might underlie the changes in membrane excitability. Such alterations may serve to enhance the efficiency by which painful stimuli are transduced and then conducted to the central nervous system. In these studies, we employed immunocytochemical methods to investigate the changes in sodium channel expression in dorsal root ganglia of rats following a subcutaneous injection of complete Freund's adjuvant, an inducer of chronic inflammation. We find that sodium channel immunoreactivity within primary sensory neurons is dramatically increased within 24 h of the complete Freund's adjuvant injection. These changes persist in small neurons for at least 2 months and roughly parallel the time course of behaviorally measured changes in pain thresholds. Thus, the regulation of sodium channel synthesis may play a role in the generation and maintenance of the hyperesthetic state seen in chronic inflammation.

Animals↗
PubMed1998

Focal conduction block in n-hexane polyneuropathy.

A 19-year-old man with an asymptomatic history of recreational gasoline vapor inhalation presented with subacute progressive quadriparesis. For 2 weeks, he had intensely inhaled Coleman fuel oil vapor, which contains n-hexane. Nerve conduction studies including near-nerve needle stimulation showed focal conduction block in the bilateral median and ulnar nerves. Sural nerve biopsy was consistent with giant axonal neuropathy. Conduction block as seen in this case has not heretofore been described in n-hexane polyneuropathy.

Administration, Inhalation↗
PubMed1998

Cocaine-induced peripheral vascular occlusive disease--a case report.

Two patients with cocaine-induced peripheral vascular occlusive disease are presented. A 37-year-old man was admitted to the hospital for evaluation of severe pain and numbness of his feet. He had used cocaine prior to admission. Arteriography showed bilateral occlusions of superficial femoral, popliteal, and trifucation arteries. Despite repeated infusions of urokinase, he developed progressive bilateral gangrene of both legs necessitating bilateral below-knee amputations. The second patient developed similar symptoms after smoking cocaine. Arteriography showed vasospasm bilaterally from the iliac arteries distally. I.v. nitroglycerin infusion caused resolution of the vasospasm and ischemic symptoms.

Acute Disease↗