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Biomedical subjects

M Miller

Publications and source records attributed to M Miller.

At least 667 records · Page 37Linked to original sources

Nocturnal plasma prolactin rise in patients with complex partial seizures.

We measured plasma prolactin and cortisol concentrations in 12 epileptic men with complex partial seizures during all-night polygraphic recording, with continuous video monitoring and sequential blood sampling at 30-minute intervals. There was a significant but moderate elevation of all-night mean plasma prolactin concentration (p less than 0.001), but not of cortisol, in epileptics when compared with normal subjects studied in a similar fashion. The data obtained in this environmentally controlled study of males with complex partial seizure disorder indicate a disruption of prolactin regulatory mechanisms resulting in a modest elevation of plasma concentrations independent of ictal electrographic discharges.

Adult↗

A morphologic and morphometric analysis of the aqueous outflow system of the developing cat eye.

The cellular and tissue changes accompanying the development and growth of the aqueous outflow system of the cat were investigated by quantitative light microscopy and by scanning and transmission electron microscopy. As in primates, the trabecular beams and sheets of the cat aqueous outflow system developed by reorganization of cells and extracellular matrix within the tissue filling the anterior chamber angle recess. Enlargement and coalescence of intercellular spaces gave rise to intertrabecular channels. From 3 to 9 days after birth, communications were established between the anterior chamber and intertrabecular spaces by perforation and resorption of tissue which initially covered the angle apex and appeared to be a peripheral extension of Descement's membrane and the corneal endothelium. Macrophage-like cells could be involved in this process. A rapid increase in the volume of the intertrabecular spaces and in the number of trabecular cells coincided with the opening of the trabecular meshwork to the anterior chamber. The trabecular meshwork grew 150-fold in volume from birth to adulthood, mainly as a result of a similar-fold expansion of its connective tissue components. The volume of the intertrabecular spaces increased 24-fold and trabecular cell number increased 14-fold during this same period. The disproportionate increase in volume of the various components of the trabecular meshwork was responsible for the decreased cell density and rarefaction displayed by this tissue as development progressed. Development of the aqueous outflow system of the cat is thus a complex, but highly co-ordinated, process, that depends on continued proliferation of cells and extracellular matrix, a progressive ordering of these components, and selective atrophy and removal of specific tissue components.

Aging↗

Altered emotionality of the vasopressin-deficient Brattleboro rat.

Observation of open field behavior of vasopressin-deficient (DI) and normal Long-Evans rats indicated elevated levels of open field activity for the DI rats. Exposure to an acoustic stressor resulted in decreased activity in both groups of animals but with a lesser effect on the DI rat. Handling prior to experimentation diminished the differences between DI and normal rats. Although both groups displayed an equivalent rise in plasma corticosterone in response to the open field, the addition of the acoustic stressor resulted in greater elevation of corticosterone in the normal animals. The behavioral and hormonal data suggest that the DI rat exhibits decreased emotional reactivity. Measurement of brain neurotransmitter levels revealed higher concentrations of serotonin, norepinephrine and dopamine in the limbic regions of the DI rat. These alterations may underlie the behavior reflecting decreased emotionality of the DI rat. In turn, the altered emotional state may be the basis for alteration in performance on learning/memory tasks of these animals. Thus, vasopressin effects on the retrieval and/or consolidation of information may not be direct but rather through its ability to influence the emotional state of the animal.

Acoustic Stimulation↗

Discordant monozygotic twins with trisomy 13.

Monozygotic twins with typical trisomy 13 are reported. Despite an identical karyotype, the twins were dimorphic for the presence of an omphalocele. Reasons for the rarity of MZ twins with trisomy 13 are presented. It is suggested that the presence of a chromosomal abnormality in MZ twins may predispose to dimorphism.

Child, Preschool↗

Measures of the sentence intonation of read and spontaneous speech in American English.

The visual abstraction procedure used in previous studies of declination was tested using 12 subjects who each fit the F0 contours of 19 spoken short simple sentences with baselines. These baselines were found to be poorly replicated the fitters. An objective all-points least-squares best-fit procedure was tested on this corpus and on a set of sentences that had been produced in both spontaneous and read speech by six speakers. The all-points linear regression line was a better descriptor of the F0 contours than either baselines or toplines. Declination did not always occur in these simple declarative sentences; there was more variation present in the F0 contours of sentences that had been uttered during spontaneous speech; 35% of the spontaneous sentences did not show declination; 45% of these sentences better fit the breath-group model. Their F0 contours could be described by a level all-points linear regression line followed by a falling terminal segment.

Adult↗

Preparation and characterization of monoclonal antibodies to the trichothecene mycotoxin T-2.

Two mouse immunoglobulin G1 monoclonal antibodies that bind to the trichothecene mycotoxin T-2 were prepared. These antibodies, designated 12C12 and 15H6, had affinities for T-2 of 3.5 X 10(6) and 5.8 X 10(7) liters/mol, respectively. A competitive inhibition enzyme immunoassay that employed these antibodies had a sensitivity for T-2 of 50 ng per assay. Both antibodies bound to the metabolite HT-2 but not to the related trichothecenes monoacetoxyscirpenol, diacetoxyscirpenol, deoxynivalenol, and deoxyverrucarol. Evidence is presented that T-2-protein conjugates inhibit protein synthesis in lymphoid cells and that this apparent immunotoxicity may be due to the release of T-2 from the protein carrier.

Animals↗

Nonuniformity of inner and outer systolic wall thickening in conscious dogs.

Transmural differences in systolic wall thickening were analyzed in 13 conscious dogs by implanting sonomicrometers to continuously measure total wall thickness (WT) and outer WT approximately half the distance through the myocardium at a closely adjacent location. Inner WT was derived by subtraction of outer WT from total WT. Outer wall measurements spanned, on average, the outer 44 +/- 10% (+/- SD) of the wall; derived inner wall measurements spanned the remaining 56 +/- 10%. At rest the fractional contribution (FC) of the outer wall to total systolic wall thickening was 29 +/- 9%, which was significantly less than the FC of the inner wall, 71 +/- 9%. These data are in good agreement with simplified modeling of a cross section of the left ventricle as two concentric rings that predicts that the FC of inner and outer halves of the wall should be approximately 67 and 33%, respectively. During treadmill exercise, the extent of both inner and outer thickening increased significantly (30 and 29%, respectively) but the relative FC of the inner and outer wall remained the same. The data indicate that systolic wall thickening is nonuniform and that this nonuniformity remains constant during the increased inotropic and chronotropic stimulation associated with exercise.

Animals↗

Evaluating drug effectiveness in an office setting for children with attention deficit disorders.

Stimulant medications have been demonstrated to be useful in treating groups of children with attention deficit disorders, but placebo effects and situational differences in behavior in individual cases need to be followed and assessed. A simple procedure for systematically assessing these factors in the individual child in the office setting is described and illustrated. The procedure provides an objective means of determining the drug and placebo effects on the reported problem behavior and the differences between parent and teacher perceptions of the behavior.

Ambulatory Care↗

A statistical model for species extrapolation using categorical response data.

Predictions of human health risk for single chemicals are often based on animal studies and hence require some sort of adjustment for species differences in toxic susceptibility. In the past, either the animal dose has been divided by an uncertainty factor or the dose has been transformed by a mathematical model into a human equivalent dose. A generalization of the allometric model previously used for carcinogens, the so-called "surface area model," is investigated here for use with graded severity response data for noncarcinogenic systemic toxicity. Statistical methods for estimating one of the model's parameters, the power of body weight, are proposed and tested on simulated and actual toxicity data. Early results indicate reasonable accuracy if data are available for a large number of dose groups.

Animals↗

Calcitonin produces hypercalcemia in leopard sharks.

Calcitonin was detected by RIA in sera from four marine species, leopard sharks (Triakis semifasciata), horn sharks (Heterodontus francisci), thornback rays (Platyrhinoides triseriata), and kelp bass (Paralabrax clathratus). These animals have levels of calcitonin and calcium higher than freshwater and terrestrial species have. The administration of salmon calcitonin to bass (4 micrograms/kg BW) produced hypocalcemia and hypophosphatemia as has been reported for other bony vertebrates. In marked contrast, calcitonin produced a prompt hypercalcemia in sharks; the average was 9.8% increase in serum calcium in nine animals with no attendant change in phosphorus. These findings demonstrate that calcitonin can increase serum calcium in sharks. Because shark skeleton is composed of cartilage, this hypercalcemic effect of calcitonin does not require a bony skeleton.

Animals↗

Failure of postictal growth hormone rise in a patient with thalamic lesions.

A patient with bilateral thalamic lesions had a spontaneous generalized convulsion during nocturnal polygraphic recording. Postictal measurements of cortisol and prolactin showed the expected rise of plasma values at 30 and 60 minutes after the seizure, but growth hormone did not increase. This observation suggests that suprahypothalamic mechanisms regulating growth hormone release differ from those involved in the neural control of cortisol-ACTH and prolactin secretion. The thalamus may intervene as a regulatory center in the release of growth hormone.

Adult↗

Noise exposure levels from model airplane engines.

Previous research indicates that noise levels from unmuffled model airplane engines produce sufficient noise to cause TTS. The present study explored SPLs of smaller engines under 3.25 cc (.19 cu. in.) and the effectiveness of engine mufflers. Results showed that model airplanes can exceed a widely used damage risk criterion (DRC) but that engine mufflers can reduce levels below DRC. Handling model gasoline engines should be added to the list of recreational activities such as snow-mobile and motorcycle riding, shooting, etc. in which the participant's hearing may be in jeopardy. Suggestions are presented to the model engine enthusiast for avoiding damage to hearing.

Aircraft↗