Biomedical subjects
J D Miller
Publications and source records attributed to J D Miller.
Rate-responsive ventricular pacing in pediatric patients.
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A two-site monoclonal antibody ELISA for the quantification of the major Dermatophagoides spp. allergens, Der p I and Der f I.
A two-site monoclonal antibody (Mab) ELISA was developed to measure the Group I allergens from Dermatophagoides spp., Der p I from D. pteronyssinus and Der f I from D. farinae. Species-specific Mabs were used to coat microtiter plates which were then incubated with allergen or house dust extracts. Bound allergen was detected using a biotinylated Mab which recognized a common epitope on both Der p I and Der f I, followed by the addition of streptavidin-peroxidase and ABTS/H2O2 substrate. The assay had low non-specific binding (approximately 0.08 absorbance units) and had a sensitivity of 5 ng/nl for aqueous allergen extracts (equivalent to 0.1 microgram allergen/g dust). 53 dust samples were assayed using the Mab ELISA and an RIA previously described using 125I-labelled Mab. The results showed a very good quantitative correlation between the assays (r = 0.96, p less than 0.001 for Der p I; r = 0.92, P less than 0.001 for Der f I). A further 132 dust samples from a different geographical areas were also assayed by both methods and gave correlation coefficients of 0.90 (P less than 0.001) and 0.86 (P less than 0.001) for Der p I and Der f I, respectively. The Mab ELISA will be useful in epidemiological studies of allergic asthma, both in the assessment of levels of dust mite allergen present in houses and the efficacy of allergen avoidance regimes.
The retinohypothalamic tract in the cat: retinal ganglion cell morphology and pattern of projection.
The pattern of retinal projection to the hypothalamus and the morphological properties of the retinal ganglion cells that comprise the retinohypothalamic tract have been examined in the cat. Intraocular injections of horseradish peroxidase revealed a dense retinal projection to the ventral suprachiasmatic nucleus; however, lighter projections were seen in the dorsal suprachiasmatic nucleus, and in hypothalamic regions both dorsal and lateral to the suprachiasmatic nucleus. Intrasuprachiasmatic nucleus injections of horseradish peroxidase retrogradely labelled retinal ganglion cells that were small to medium in soma size. The labelled ganglion cells exhibited long thin dendrites that were sparsely branched. The labelled retinal ganglion cells exhibited a significant change in soma size associated with retinal eccentricity. The morphological characteristics of the ganglion cells that project to the suprachiasmatic nucleus are similar to those of gamma cells.
Effects of microgravity on brain neurotransmitter receptors.
Neurotransmitter receptor binding and Na+, K+-ATPase activity were examined in the brains of six rats exposed to 7 days of microgravity during the flight of Spacelab 3. The same variables were examined in a group of six ground control rats. 5-HT1 receptor number in the hippocampus was significantly elevated by exposure to the microgravity environment, and cortical sodium-potassium pump activity was significantly depressed. A marginal depression in dopamine D-2 binding in the striatum was noted. Dopamine and 5-HT binding in a wide variety of other central regions, in addition to GABAA, muscarinic acetylcholine, adenosine A1, and opiate receptor binding, and adrenoceptor binding, was unaffected by microgravity exposure.
Head injuries in elderly patients.
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Synovial cyst at the craniovertebral junction.
A case of synovial cyst of the upper cervical spine that resulted in spastic quadriparesis and sensory loss is reported. Radiographic evaluation included a computed tomography scan after myelography and a magnetic resonance imaging scan. The synovial cyst was removed by a laminectomy at C-1 and C-2, combined with a foramen magnum craniectomy. The patient had a good recovery.
Disseminated intravascular coagulation associated with spinal cord laceration: a case report.
A 31-year-old man was thrown from his motorcycle, sustaining a thoracolumbar fracture and cervical spine fracture with no evidence of neurologic function below L1. At the time of spinal fusion, there was diffuse bleeding from the soft tissues. Visualization of the thoracolumbar fraction revealed separation of the laminae with a dural tear and extruding spinal cord tissue. Laboratory evaluation identified abnormal clotting studies intraoperatively and postoperatively. We postulate that release of potent spinal cord thromboplastins into the systemic circulation may elicit a coagulopathy, as has been recognized following craniocerebral trauma.
GnRH analog delivery systems: present and future options.
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Auditory-perceptual interpretation of the vowel.
The major issues in relating acoustic waveforms of spoken vowels to perceived vowel categories are presented and discussed in terms of the author's auditory-perceptual theory of phonetic recognition. A brief historical review of formant-ratio theory is presented, as well as an analysis of frequency scales that have been proposed for description of the vowel. It is illustrated that the monophthongal vowel sounds of American English can be represented as clustered in perceptual target zones within a three-dimensional auditory-perceptual space (APS), and it is shown that preliminary versions of these target zones segregate a corpus of vowels of American English with 93% accuracy. Furthermore, it is shown that the nonretroflex vowels of American English fall within a narrow slab within the APS, with spread vowels near the front of this slab and rounded vowels near the back. Retroflex vowels fall in a distinct region behind the vowel slab. Descriptions of the vowels within the APS are shown to be correlated with their descriptions in terms of dimensions of articulation and timbre. Additionally, issues related to talker normalization, coarticulation effects, segmentation, pitch, transposition, and diphthongization are discussed.
Evaluation of the Abbott TESTPACK RSV enzyme immunoassay for detection of respiratory syncytial virus in nasopharyngeal swab specimens.
The Abbott TESTPACK RSV assay (Abbott Laboratories, North Chicago, Ill.), a rapid (20-min) enzyme immunoassay, was compared with culture and direct immunofluorescence (DFA) of nasopharyngeal cells for the detection of respiratory syncytial virus (RSV) in nasopharyngeal swab specimens. Nasopharyngeal swab specimens, collected from 234 infants, were placed in viral transport medium. Portions of specimen in transport medium were used for each test. Of 234 specimens, 70 (30%) were culture positive, 103 (44%) were DFA positive, 107 (46%) were culture or DFA positive, and 112 (48%) were TESTPACK RSV positive. Of 19 specimens positive by TESTPACK RSV but negative by culture or DFA, 15 were positive by the blocking assay. A total of 122 specimens were culture, DFA, or blocking assay positive; TESTPACK RSV detected 108 specimens (sensitivity, 89%). The specificity, positive predictive value, and negative predictive value of TESTPACK RSV as compared with those of culture, DFA, and the blocking assay were 96, 96, and 89%, respectively. By comparison, the sensitivity, specificity, positive predictive value, and negative predictive value of combined culture and DFA were 88, 100, 100, and 88%, respectively. TESTPACK RSV is a rapid and reliable enzyme immunoassay for the direct detection of RSV antigen in nasopharyngeal swab specimens.
Alzheimer's disease: longitudinal CT studies of ventricular change.
A 3-year longitudinal study was conducted with 50 Alzheimer's disease patients and 45 elderly control subjects. All study participants received an extensive evaluation that included brain CT at baseline and follow-up. Quantitation of ventricular size, using both linear and volume methods, revealed highly significant cross-sectional and longitudinal differences between the Alzheimer patients and control subjects. Specifically, the annual rate of change in ventricular volume was approximately 9% in the Alzheimer patients and approximately 2% in the controls. The presence of age-related white matter lesions had no effect on the clinical course of the patients or on the changes in ventricular size. Among the Alzheimer patients, the rate of clinical decline was strongly related to the rate of change in ventricular size. Baseline ventricular measurements were of no value in predicting the subsequent rate of clinical deterioration or ventricular enlargement. The results suggest that changes in ventricular size closely reflect the clinical changes in Alzheimer patients.
Outcome following aneurysm wrapping: a 10-year follow-up review of clipped and wrapped aneurysms.
One hundred and eighty-one patients with single aneurysms involving the anterior circulation were treated either by wrapping (60 cases) or clipping (121 cases), and 96.1% of them were followed for 10 years. The rate of early rebleeding (less than 6 months) from wrapped aneurysms was 8.6% (confidence interval 1.4% to 15.8%) and the late rebleeding (6 months to 10 years) rate was 1.5% per annum (confidence interval 0.3% to 2.5%/yr). Wrapping an aneurysm offers some protection from rebleeding, particularly during the first 6 months when the risk of rebleeding is high.
Gas gangrene occurring soon after compound depressed skull fracture.
Two cases of Clostridium perfringens infection occurring less than 24 hours after compound depressed skull fracture are reported. The infection was principally intracranial in the first and extracranial in the second; both required surgical debridement and antibiotic treatment. Attention is drawn to the rapidity with which a potentially life-threatening infection can develop in civilian head injury and to the implications for acute management of patients with compound depressed fractures.
Reactions of patients with focal cerebral lesions to success or failure.
Multiple measures were used to investigate emotional reactions to card sorting in patients with focal cerebral lesions and in matched non-brain-injured controls. Spontaneous facial expressions of patients with anterior lesions were impoverished, relative to the posterior group, on a quantitative index of facial movement. This deficit did not appear to be attributable to group differences on lesion variables, or degree of cognitive deficit. There were also indications that a "non-emotional" facial-motor deficit was not the primary cause. The marked anterior deficit for facial movement was not, however, associated with equally pronounced deficits on qualitative, self-report and heart rate indices of emotional response. Right hemisphere patients differed from left hemisphere patients on only one qualitative measure of emotional reaction, but this may have been due to the stronger negative reactions of dysphasic patients. Left unilateral neglect was not associated with reduced emotional response.
Multicentric glioma presenting with hemorrhage.
We report a case of multicentric malignant astrocytoma occurring simultaneously in both cerebrum and cerebellum, presenting with hemorrhage into the cerebellar tumor. Hemorrhage into a cerebellar glioma in an adult is very rare. None of the cases of multicentric glioma described in the literature presented with intratumoral hemorrhage. This combination in our patient has prompted us to report this case and to reaffirm the need to consider the diagnosis of malignant glioma in patients with multiple intracranial tumors.
Response to heavy nitrogen applications in fertilizer experiments in British forests.
Increasing concern over the level of nitrogen inputs to forests in polluted rain has led to a number of suggestions of possible adverse consequences under the general heading of nitrogen saturation. A saturated ecosystem may be one (a) in which the trees show no growth response to the addition of further nitrogen, (b) in which addition of further nitrogen leads to growth disturbances or reduction, or (c) in which elevated nitrogen inputs lead to increased losses of nitrate in streamwater. Experience gained from forest fertilizer experiments is used to examine each of these suggestions. A definition involving a lack of growth response (a) is shown to be based on a lack of understanding of the continuing changing patterns of nitrogen demand and mineralization in even-aged forests. Similarly, using growth disturbances (b) is unsatisfactory because, it is suggested, these are either secondary deficiencies that appear once growth accelerates with added nitrogen or are a consequence of changing growth with increasing size. A definition based on increased loss of nitrate is, by analogy with the situation for sulphate, at least superficially attractive. However, the fact that nitrate retention is predominantly biological, rather than chemical, makes for difficulties and the limited evidence available suggests that many exceptions and variations may exist. Whilst experience with forest fertilizers might not be entirely apposite, for example foliar uptake from polluted rain may be a factor, it is urged that at least any hypothesis put forward should be compatible with information gained from fertilizer trials.
Pharmacokinetic fate of 14C-labeled deoxynivalenol in swine.
The pharmacokinetics of the trichothecene mycotoxin deoxynivalenol (DON) was investigated in swine following intravenous (0.30 mg, 0.35 microCi/kg) and intragastric (0.60 mg, 0.60 microCi/kg) administration of the 14C-labeled toxin. After iv dosing, plasma concentration data favored a three-compartment open model with half-life values for the rapid distribution (alpha), slower distribution (beta), and terminal elimination (gamma) phases of 5.8, 96.7, and 510.0 min, respectively. The apparent volume of distribution (V'd) was 1.34 liter/kg, the volume of the central compartment (Vc) was 0.166 liter/kg, and the plasma clearance was 1.81 ml/min/kg. DON was rapidly cleared essentially unchanged (greater than 95%), and was excreted primarily in urine (86-104%), with minor elimination in bile (3-5%). Following intragastric dosing DON was very rapidly absorbed, reaching near peak plasma levels within 15-30 min. Levels remained elevated (63-325 ng/ml) for approximately 9 hr, and began declining slowly (t1/2 beta = 7.1 hr) thereafter. The calculated systemic bioavailability (F) was between 48 and 65%, although urinary and biliary recoveries indicated marginally greater absorption actually occurred (54-85%). Overall, although DON was eliminated rapidly and completely within 24 hr following a single iv or intragastric dose, data suggest that residues may undergo temporary sequestration in a tissue depot.