PubMed Health⌕ Search

Biomedical subjects

J F Howard

Publications and source records attributed to J F Howard.

At least 55 records · Page 3Linked to original sources
PubMed1988

Immediate effects of intravenous IgG administration on peripheral blood B and T cells and polymorphonuclear cells in patients with myasthenia gravis.

Five patients with myasthenia gravis, who received treatment with intravenous 7S gamma-globulin were monitored for changes in immunological status. Serum immunoglobulin G increased from an average of 1.4 to 4.7 g/dl during the 5-day course of therapy. Specific antibody to the acetylcholine receptor present in three of five patients did not change. A transient decrease in total peripheral blood leukocytes was observed in five patients due to decreases in the absolute number of polymorphonuclear cells and lymphocytes in the circulation. Lymphocyte surface marker studies revealed that the percentage of surface immunoglobulin positive cells increased in all patients from an average of 13 to 26% by day 5 of therapy; however, the percentage of HLA-Dr- and Leu 12 (CD19)-positive B cells did not change. Lymphoid cells positive for the Leu 11 (CD16) marker doubled from an average of 11 to 24% during the 5-day course of therapy. Surface Ig-positive cells and Leu 11 (CD16)-positive cells returned to pretreatment values by 7 days posttherapy. Helper/suppressor cell ratios slowly decreased in all patients from an average of 2.9 to 2.2 by 1 week posttherapy and remained low for several weeks.

B-Lymphocytes↗
PubMed1987

Incidents of auditory perception during anaesthesia with traumatic sequelae.

The literature on auditory perception during anaesthesia, while by no means scarce, presents contradictory experimental findings; its reported prevalence ranges from nil to 80%. Due to their anecdotal nature and lack of control, case histories are difficult to evaluate statistically. Nevertheless, they provide a broader base for the understanding of the phenomenon and its implications. Two case histories are presented, both with traumatic sequelae. In the first case, the anaesthetist confirmed his off-the-cuff utterance that was perceived by the patient and retained in the anaesthetized patient's memory and acted upon by the patient postoperatively. A possible explanation of auditory perception and its behavioural characteristics are outlined. A suggestion is offered for the potential beneficial application of auditory perception during anaesthesia.

Adult↗
PubMed1985

Automated data acquisition and analysis of neural evoked potentials.

A software system to collect, analyze and store trains of neural evoked potentials is presented. Real-time waveform capture permits sampling of a variable-duration data window of 6 to 399.6 ms with a sample delay accurately adjustable up to 1 001 ms (20 microseconds resolution). The digitized representation of each waveform is stored for individual analysis. Off-line processing determines 17 parameters of each waveform, including an arrow-selected amplitude and time. Individual processing of waveforms preserves all degrees of freedom for statistical analysis across waveforms. Ensemble averages may optionally be formed from the individual waveforms with processing performed on the averaged responses. The software provides MENU-selectable support functions including stimulus-to-artifact timing, storage and retrieval of data and calculated parameters, digital display of waveforms, data calibration and gain modification, table referenced data editing, file management, simple statistics, hardcopy output, and optional database interfacing with output formatted for compatibility with a statistics package (SAS).

Animals↗
PubMed1983

Interpretation of cerebrospinal fluid protein assays in various neurologic diseases.

Albumin and immunoglobulin G (IgG) were determined in cerebrospinal fluid (CSF) and serum, and the CSF/serum albumin Index (CSF X 10(3)/serum albumin concentration ratio) and IgG Index [(CSF/serum IgG)/(CSF/serum albumin)] were calculated. Data for these indices and oligoclonal banding are described in 23 cases of multiple sclerosis (MS), 19 of systemic lupus erythematosus (SLE), eight of sarcoidosis, 48 cases of miscellaneous disease, and 25 control patients with nonspecific complaints. Of the MS, SLE, and sarcoidosis patient groups, 8.5%, 26%, and 12.5% showed an abnormally high CSF/serum albumin Index; 87%, 16%, and 0% an increased IgG Index; and 87.5%, 42% and 0% showed positive oligoclonal banding. IgG Index and oligoclonal banding results for MS patients differed significantly from the sarcoidosis (p less than .001) and SLE (p less than .05) groups. When the CSF/serum albumin Index is considered also, the control and sarcoidosis patient results differ significantly from the MS group (p less than .001 and p less than .01). A strong correlation between the IgG Index and oligoclonal banding is implicated.

Blood-Brain Barrier↗
PubMed1981

Intercostal muscle biopsy studies in myasthenia gravis: clinical correlations and the direct effects of drugs and myasthenic serum.

We have found a wide range of mean MEPP amplitude in intercostal muscle biopsies from 43 patients with MG, including several values in the normal range. There was no correlation between MEPP amplitude and the severity of clinical disease as assessed by manual muscle testing or by single-fiber EMG measurements of jitter in arm muscles. Through most of these patients were in a state of clinical remission or marked improvement after treatment with prednisone, we could not attribute the difference between our results and those of others to this factor alone. The application of morphine, meperidine and aminoglycoside antibiotics to intercostal muscle in vitro confirms effects previously demonstrated in rat muscle: (1) At equal therapeutic concentrations, meperidine has greater neuromuscular blocking effects than does morphine, but neither has significant effects at concentrations achieved in the serum clinically. (2) Tobramycin, netilmicin and neomycin have varying severity and sites of action, but their effects are the same in human myasthenic muscle as in normal rat muscle. Bath application of serum from myasthenic patients produces an acute, reversible worsening of neuromuscular blockade in myasthenic muscle. Electrophysiologic measurements in intercostal biopsies from patients with MG can provide information about the basic abnormality of neuromuscular transmission in this disease and can confirm the relevance of studies made in animal muscle.

Action Potentials↗
PubMed1980

Passive transfer of human myasthenia gravis to rats: 1. Electrophysiology of the developing neuromuscular block.

Adult female Lewis rats were rendered immunologically tolerant to human gamma globulin, and were given a single intravenous injection of human myasthenic or normal control serum containing 7.5 to 12 mg of immunoglobulin G. The mean amplitude of miniature endplate potentials (MEPPs) in the forelimb flexor digitorum longus muscles from treated animals did not differ from control values during the first 24 hours after serum injection. Subsequently, MEPP amplitude was reduced in muscles from animals that had received myasthenic serum; maximum reduction was reached by 6 days after transfer. Mean MEPP amplitude at maximum reduction was 30 to 40% below the amplitude of controls and returned to control values 14 weeks after transfer. Similar reductions in endplate potential amplitudes were found in immunologically tolerant animals receiving myasthenic serum. No significant reduction of MEPP amplitude was seen in recipients that were not immunologically tolerant or that had received cobra venom factor to reduce complement activity. The delayed development of reduced MEPP amplitude indicated that the defect of neuromuscular transmission produced by myasthenic serum was not due entirely to a simple curare-like block of the acetylcholine receptor site by an IgG antibody.

Action Potentials↗
PubMed1979

Single-fiber electromyography in myasthenia gravis.

One-hundred-sixty single-fiber EMG studies of the extensor digitorum communis muscle were performed on 127 patients with myasthenia gravis; 131 demonstrated defective neuromuscular transmission. Jitter determinations in the biceps, deltoid or frontalis muscles increased the diagnostic yield significantly. Evoked-potential EMG studies were abnormal in less than 50 percent of patients in whom they were performed. The most sensitive criterion of abnormality was the percentage of fibers with increased jitter; the sensitivity of the test was enhanced, however, if the mean jitter of the tested muscle was also used as a criterion of abnormality. Since increased jitter may also be seen in primary muscle and nerve disease, these disorders must be excluded by other means before diagnosing myasthenia gravis on the basis of the single-fiber studies.

Adult↗
PubMedDate not supplied

AAEE minimonograph #25: Single-fiber electromyography in myasthenia gravis.

Single-fiber electromyography (SFEMG) demonstrates abnormal jitter in virtually all (99%) patients with myasthenia gravis (MG). One muscle, the extensor digitorum communis, is abnormal in most patients with this disease, but to obtain the maximum diagnostic sensitivity, it may be necessary to examine other muscles, especially ones that are more involved clinically. There is no one muscle that will be more abnormal in every patient with MG. The muscle(s) to be tested must be selected based on the distribution of weakness in the individual patient. Abnormal jitter is also seen in diseases of nerve and muscle; these diseases must be excluded by other electrophysiologic and clinical examinations before diagnosing MG. If neuronal or myopathic disease is present, increased jitter does not indicate that MG is also present. However, if jitter is normal in a muscle with definite weakness, the weakness is not due to MG. When abnormal neuromuscular transmission has been demonstrated by repetitive nerve stimulation, the finding of abnormal jitter does not add to the diagnosis, though it may be useful in providing baseline values for comparison with the results of subsequent studies. SFEMG is most valuable clinically in the patient with suspected MG in whom other tests of neuromuscular transmission and antiacetylcholine receptor antibody titers are normal. Serial measurements of jitter can be useful in following the course of disease and in assessing the effect of treatment, but the results from these studies must always be interpreted in light of the overall clinical picture.

Autoantibodies↗