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Biomedical subjects

D R Cornblath

Publications and source records attributed to D R Cornblath.

At least 91 records · Page 5Linked to original sources
PubMed1991

Molecular insight into the asymmetric distribution of pathogenetic human mitochondrial DNA deletions.

Pathogenetic human mitochondrial DNA deletions occur very rarely in the minor region between the origins of replication. In order to understand the molecular basis of this asymmetry, we analyzed the structure of such a 4.680 kilobase deletion (position 471 - 5151). Directly repeated sequences (12/13 nucleotides) are present in the deletion junction, both promoters of heavy chain replication and both ribosomal RNA genes are deleted, and the 5' extent further narrows the absolute limits of mitochondrial DNA deletions. Several factors are identified that may contribute to the paucity of minor region deletions.

Base Sequence↗
PubMed1991

Treatment of chronic inflammatory demyelinating polyneuropathy with intravenous immunoglobulin.

Chronic inflammatory demyelinating polyneuropathy is an immune-mediated demyelinating peripheral neuropathy usually treated with immunosuppressants. We reviewed our experience treating 15 patients (9 men, 6 women) with intravenous immunoglobulin. Six patients were on other therapies at the time of intravenous immunoglobulin infusions (4, prednisone; 2, prednisone and azathioprine). The dose of intravenous immunoglobulin was either 0.3 or 0.4 gm/kg/day for 4 to 5 days. Transient fever occurred in 1 patient. Subjective improvement in sensory symptoms was reported by almost all patients. Objective improvements in strength or functional tasks occurred in only 3 patients, a man with human immunodeficiency virus infection, a 14-year-old girl, and a woman with an immunoglobulin G kappa paraprotein. Our results suggest that individual patients may respond to intravenous immunoglobulin therapy. A multicenter controlled trial is needed to assess properly the role of intravenous immunoglobulin therapy in patients with chronic inflammatory demyelinating polyneuropathy.

Adolescent↗
PubMed1991

Inter- and intra-examiner reliability of nerve conduction measurements in normal subjects.

Nerve conduction studies are widely employed in evaluating patients with peripheral nerve disease and are often used serially to measure disease progression or to assess a therapeutic intervention. We determined the inter- and intra-examiner reliability of electrophysiological data by performing serial nerve conduction studies on 7 normal subjects. A high degree of intra-examiner reliability was present, but significant inter-examiner differences were found. Our results suggest that if nerve conduction studies are to be used longitudinally, they should optimally be performed by a single examiner to minimize the degree of variability associated with different examiners.

Electromyography↗
PubMed1991

Conduction block in diabetic neuropathy.

Symmetric sensorimotor polyneuropathy is a common complication of diabetes. Sensory and motor evoked amplitudes and conduction velocities are reduced. Both demyelination and axon loss have been reported in pathologic studies. Conduction block (CB), a manifestation of segmental demyelination, has not been previously studied in diabetic neuropathy. We determined the prevalence of conduction block in patients with diabetes by analyzing electrodiagnostic data from 24 diabetics. Conduction block was defined as a greater than 20% drop in peak-to-peak amplitude, and a less than 15% change in negative-peak duration between proximal and distal stimulation sites. A total of 76 nerve segments were studied. The criteria for conduction block were met in only 6 segments in 6 patients. The mean decrease in peak-to-peak amplitude between stimulation sites was 28% (range 21% to 40%). We conclude that conduction block over long nerve segments is uncommon in diabetic neuropathy, and, if present, suggests that other causes for neuropathy in diabetic patients should be sought.

Demyelinating Diseases↗
PubMed1991

Stimulated single-fiber electromyography in Lambert-Eaton myasthenic syndrome.

The Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disorder of neuromuscular transmission. Electrodiagnosis is confirmed by an increase in compound muscle action potential amplitude during high-frequency repetitive nerve stimulation or following brief exercise. We describe the results of stimulated single-fiber electromyography in 4 patients with disorders of neuromuscular transmission: LEMS (2), LEMS/myasthenia gravis (MG) overlap (1), and MG (1). Stimulated SFEMG was performed in the extensor digitorum communis muscle with axonal intramuscular suprathreshold stimulation at low and high rates. In all 4 patients, a rate dependence of jitter was found. In LEMS and LEMS/MG, jitter and blocking improved with high stimulation rates, as compared with the opposite effect in MG. We conclude that stimulated SFEMG is a valuable technique in the diagnosis of LEMS.

Aged↗
PubMed1991

Early invasive CNS aspergillosis. An easily missed diagnosis.

A 46-year-old woman with non-Hodgkin's lymphoma presented with a new onset of seizures. A cranial CT was interpreted as normal. Eight months later, she presented with changed mental status and leg weakness, and a repeat CT scan showed multiple ring-enhancing lesions close to the left frontal sinus, with mass effect. A review of the previous CT scan showed a very small area of sinusitis as well as a small ring-enhancing lesion contiguous to it. A short course of intravenous steroids markedly relieved her symptoms, and a stereotactic biopsy confirmed Aspergillus fumigatus to be the cause of the infection. She was successfully treated with Amphotericin B. Central nervous system (CNS) aspergillosis is a potentially fatal disease. The therapeutic success in this case was related to a high index of suspicion at her second presentation. As the early signs of infection might be subtle and easily missed, patients at high risk for opportunistic infection should be studied carefully when new onset of CNS symptoms occur. Early initiation of therapy should improve the prognosis in such cases.

Aspergillosis↗
PubMed1991

Neopterin and interferon-gamma in serum and cerebrospinal fluid of patients with HIV-associated neurologic disease.

We measured the levels of interferon-gamma (IFN-gamma) and neopterin in the serum and cerebrospinal fluid of 121 human immunodeficiency virus-seropositive (HIV+) and 62-seronegative (HIV-) individuals evaluated for neurologic disease. CSF levels of IFN-gamma and serum and CSF levels of neopterin were higher in HIV+ than in HIV- individuals. Patients with HIV- related meningitis and with opportunistic CNS infections had higher serum neopterin levels than HIV+ asymptomatic individuals. CSF levels of IFN-gamma were slightly higher in CSF of HIV+ individuals in all groups (0.31 +/- 0.03 U/ml) than in HIV- individuals (0.12 +/- 0.03). CSF levels of neopterin were similar in HIV+ asymptomatic individuals (6.9 +/- 0.7 nmol/l) and HIV- individuals (5.9 +/- 1.1), but were elevated in those HIV-infected individuals with neurologic disease, particularly patients with HIV-associated meningitis (72.1 +/- 13.3 nmol/l), opportunistic CNS infections (36 +/- 9.1), and inflammatory demyelinating polyneuropathies (32.4 +/- 17.2). Levels of neopterin correlated positively with levels of soluble interleukin 2 receptor and soluble CD8, 2 additional indicators of immune activation. In the absence of neurologic disease, levels of IFN-gamma and neopterin in both serum and CSF were stable for up to 4 years after seroconversion. These data suggest that increased CSF neopterin is associated with HIV-associated neurologic disease.

Biopterins↗
PubMed1991

HIV-1 infection and nervous system abnormalities among a cohort of intravenous drug users.

A group of 109 HIV seropositive and 51 seronegative intravenous drug users was evaluated for the presence of HIV-1-related neurologic disease using clinical, neurologic, neuropsychological, and electrophysiologic evaluations. About 80% of HIV seropositive subjects had less than two constitutional symptoms. CD4 cell counts were less than 500/mm3 among 56% of seropositive participants; three individuals were receiving zidovudine. Neurologic abnormalities were found frequently among the cohort, independently of HIV-1 serostatus; electrophysiologic abnormalities were uncommon. Participants from both serologic groups scored significantly lower on neuropsychological tests as compared with norms established for a cohort of homosexual men, and there was no clear association between HIV-1 serostatus and performance on these tests. This study suggests that HIV infection was not the dominant cause of neurologic abnormalities among the study cohort.

Adult↗
PubMed1990

Ataxic sensory neuropathy and dorsal root ganglionitis associated with Sjögren's syndrome.

Thirteen patients, 11 women and 2 men, developed sensory and autonomic neuronopathies in association with features of primary Sjögren's syndrome. In 11, Sjögren's syndrome had not been previously diagnosed at the time of neurological presentation. All had prominent loss of kinesthesia and proprioception. Pain and thermal sensibility were less severely affected. Most had evidence of autonomic insufficiency. In some this was severe, with Adie's pupils, fixed tachycardia, and orthostatic hypotension. The course ranged from an abrupt, devastating onset to indolent progression over years. Stabilization or functional improvement occurred in 6 patients, 2 of whom received no drug therapy. Sensory nerve conduction studies and examination of nerve biopsy specimens demonstrated a wide spectrum in the severity of loss of large myelinated fibers. The cutaneous nerves of 6 patients had perivascular mononuclear infiltrates without necrotizing arteritis. Examination of biopsy specimens of dorsal root ganglia in 3 patients revealed lymphocytic (T-cell) infiltration in the dorsal roots and ganglia, with focal clusters around neurons. In the more mildly affected ganglia, individual sensory neurons were undergoing degeneration. In the most advanced case, very few neurons remained. The possibility of Sjögren's syndrome should be considered in patients, especially women, who develop acute, subacute, or chronic sensory and autonomic neuropathies, with ataxia and kinesthetic loss.

Adult↗
PubMed1990

Lower motor neuron syndromes defined by patterns of weakness, nerve conduction abnormalities, and high titers of antiglycolipid antibodies.

We studied 74 patients with progressive, asymmetrical lower motor neuron syndromes. Clinical features of these patients, including age, sex, disease duration, patterns of weakness, and reflex changes, were evaluated by review of records. In each patient the clinical features were compared to the type of nerve conduction abnormalities and to the specificities of high-titer serum antiglycolipid antibodies. Antibody specificities were determined by an enzyme-linked immunosorbent assay using purified glycolipids and carbohydrates as substrates. Our results show that high titers of antibodies to glycolipids are common in sera of patients with lower motor neuron syndromes. Selective patterns of reactivity indicate that specific carbohydrate epitopes on the glycolipids are the targets of the high-titer antibodies in individual patients with lower motor neuron syndromes. Several distinct lower motor neuron syndromes can be identified based on clinical, physiological, and antiglycolipid antibody characteristics. These syndromes include multifocal motor neuropathy with evidence of multifocal conduction block on motor, but not sensory, axons and frequent (84%) high titers of anti-GM1 ganglioside antibodies; a lower motor neuron syndrome with predominantly distal weakness early in the disease course, no conduction block, and a high incidence (64%) of anti-GM1 antibodies; and a lower motor neuron syndrome with predominant early weakness in proximal muscles and serum antibodies to asialo-GM1 that do not cross-react with GM1 ganglioside.

Adult↗
PubMed1990

Electrophysiology in Guillain-Barré syndrome.

Clinical electrophysiological studies are important in the evaluation of patients with Guillain-Barré syndrome. Physiological evidence of demyelination occurs in almost all patients with Guillain-Barré syndrome, especially if serial studies are performed. Criteria for demyelination are proposed. Prognostic information concerning patient outcome can be deduced from computation of the mean of the summed motor evoked compound muscle action potential amplitudes from distal stimulation. Future studies of the electrophysiology of Guillain-Barré syndrome should allow increased use of the data for prognostication and should enhance our understanding of the mechanisms of the disease.

Humans↗
PubMed1990

Macrophage responses in inflammatory demyelinating neuropathies.

Macrophages are prominent participants in inflammatory demyelinating neuropathies. To provide a different means of evaluating macrophage behavior, we used immunostaining of teased nerve fibers and endoneurial blood vessels. We assessed the frequency with which macrophages were seen in inflammatory demyelinating neuropathies, their relationship to normal and demyelinating fibers, and their expression of major histocompatibility Class II markers (Ia antigen). In 6 patients with chronic inflammatory neuropathy and 1 with Guillain-Barré syndrome, we found regularly that macrophages were adherent to teased blood vessels. Cells presumed to be entering the nerve were elongated, often with a polarized appearance suggesting motility, and were Ia-positive. After entry into nerve, the Ia-positive macrophages were adherent to both normal and demyelinating fibers. They often retained their Ia positivity after penetrating into the nerve fiber and removing myelin. Foamy macrophages, judged to be postphagocytic, were Ia-negative. The foamy macrophages found adhering to blood vessels were presumed to be leaving the nerve. This pattern of entry as Ia-positive prephagocytic cells and evolution to Ia-negative foamy macrophages was compared with other experimental and human neuropathies.

Demyelinating Diseases↗