Double outlet right ventricle and other associated congenital cardiac anomalies in an American miniature horse foal.
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Animals↗
Biomedical subjects
M W Miller
Publications and source records attributed to M W Miller.
Cholinergic transmission at the first synapse of the circuit mediating the crayfish lateral giant escape reaction.
1. The chemical synapses between mechanoreceptor neurons and first-order interneurons in the lateral giant (LG) neuron escape circuit of the crayfish have plastic properties, some of which are believed to be the basis for behavioral habituation and sensitization. In this investigation pharmacological experiments were conducted to assess the role of cholinergic synaptic transmission in this pathway. 2. Arterial perfusion of the cholinergic agonist carbachol produced increased activity of many abdominal nerve cord units, including an identified first-order interneuron (interneuron A) in the LG circuit. A general increase in activity of interneurons in this circuit in the presence of certain cholinergic agonists was inferred from an increase in the frequency of occurrence of spontaneous excitatory postsynaptic potentials (EPSPs) recorded in the LG. 3. Cholinergic antagonists reduced the amplitude of spontaneous and evoked sensory neuron-to-interneuron A EPSPs and decreased the disynaptic (via 1st-order interneurons) component of evoked EPSPs in the LG. These effects indicate that postsynaptic cholinergic receptors are utilized in mechanosensory synaptic transmission to the first-order interneurons of this circuit. The relative potencies of the blockers tested (mecamylamine > picrotoxin >>> curare > atropine) suggest that the receptors on the interneurons belong to a previously characterized class of crustacean cholinergic receptors that resemble the ganglionic nicotinic subtype of vertebrates. 4. Nicotinic agonists (carbachol, tetramethylammonium hydroxide, 1,1-dimethyl-4-phenyl-piperazium iodide) produced depolarizing (decreased input resistance) responses on the LG neuron itself. These responses persisted during blockade of chemical transmission by cobalt. The presence of cholinergic receptors on the LG, a cell in which all known inputs mediating sensory excitation are electrical, is discussed. 5. Application of muscarinic agonists (pilocarpine, oxotremorine) resulted in a long-lasting reduction of the evoked sensory neuron-to-interneuron A EPSP and the disynaptic component of the evoked EPSP in the LG. No effects on the membrane potential or input resistance of the interneurons were detected. It is proposed that presynaptic receptors with a muscarinic profile are present on mechanosensory neurons and that these receptors mediate a reduction of transmitter release.
Acetylcholine↗
Gross and microscopic lesions of naturally occurring tuberculosis in a captive herd of wapiti (Cervus elaphus nelsoni) in Colorado.
A Mycobacterium bovis-infected herd of captive wapiti (Cervus elaphus nelsoni) in Colorado was depopulated after lesions of bovine tuberculosis were confirmed in 8 of 10 tuberculin skin test reactors. Of the 43 animals > 1 year of age, 26 had gross lesions suggestive of tuberculosis, 24 had microscopic lesions of tuberculosis, and 23 had acid-fast bacilli associated with the lesions. Lungs and retropharyngeal lymph nodes were the most frequently affected sites. Most lesions grossly and microscopically resembled tuberculosis in cattle; however, some lesions resembled abscesses or ovine caseous lymphadenitis lesions. Special stains and immunohistochemical techniques labeled few to numerous mycobacteria associated with the lesions.
Animals↗
Using ribosomal RNA gene restriction patterns in distinguishing isolates of Pasteurella haemolytica from bighorn sheep (Ovis canadensis).
Pasteurella haemolytica isolates (n = 31) from two isolated captive herds of Rocky Mountain bighorn sheep (Ovis canadensis canadensis) were characterized and compared phenotypically (biotype, serotype, hemolytic activity) and by a genomic fingerprinting method known as ribotyping. Seven to nine distinct phenotypes were observed. Depending on the method used for serotyping, one to three phenotypes were common to both herds. Eighteen isolates, recovered from both herds, were non-hemolytic, biotype T, indirect hemagglutination assay serotype 4. Ribotyping, a method for highlighting genetically conserved deoxyribonucleic acid restriction site heterogeneity with a 32P-labelled Escherichia coli ribosomal ribonucleic acid probe, produced six to eight distinct ribotype pattern groups within the 31 P. haemolytica isolates, depending on the restriction enzyme used. In contrast to phenotypes, ribotypes appeared unique to each herd, and ribotyping helped to further differentiate some isolates of the same biotype and serotype. In addition, ribotyping provided an alternative means for evaluating relationships between isolates differing in hemolytic activity but which were otherwise phenotypically identical. We propose that ribotyping may be a useful adjunct to other bacterial characterization methods in studying the epizootiology of pasteurellosis in bighorn sheep.
Agglutination Tests↗
Ultrasonically induced in vitro cell lysis: node-antinode interactions.
An attempt was made to discriminate between two hypotheses (standing wave, bubble recycling) of the mechanism of ultrasonically induced cell lysis in a rotating tube. A tube containing an aqueous suspension of P-388 cells was moved back and forth (+/- 3 or +/- 7 mm) during insonation (1 MHz, 5 W/cm2, continuous wave, 5 min). Cell lysis (approximately 20%) occurred. As a positive control, some tubes were also partially or completely rotated during insonation; considerable cell lysis (approximately 60%) occurred. The results are interpreted to suggest that both hypotheses are simultaneously useful in explaining the observed effect of cell lysis in a rotating tube.
Air↗
Evaluation of accuracy of pulse oximetry in dogs.
The accuracy of a pulse oximeter was evaluated over a wide range of arterial oxygen and carbon dioxide tensions, using 2 probes (finger probe and ear probe) and 2 monitoring sites (tongue and tail) in anesthetized dogs. The arterial oxygen saturation of hemoglobin (SaO2) measured directly with a multiwavelength spectrophotometer was compared with saturation estimated by pulse oximetry (SpO2). Linear regression analysis of the pooled data from 399 simultaneous measurements of SpO2 and SaO2 indicated a highly significant correlation of SpO2 with SaO2 (r = 0.97; P less than or equal to 0.0001). Although the mean difference (+/- SD) between SpO2 and SaO2 for pooled data was small (-0.06 +/- 6.8%), SpO2 tended to underestimate high SaO2 values (greater than or equal to 70%) and to overestimate low SaO2 values (less than 70%). When SaO2 values were greater than or equal to 70%, the ear probe applied to the tail was less accurate (produced a significantly greater SpO2-SaO2 difference) than the ear probe on the tongue, or the finger probe at either site. When SaO2 values were less than or equal to 50%, the finger probe applied at the tail was more accurate (produced significantly smaller SpO2-SaO2 differences) than the ear probe at either site. When SaO2 values were less than or equal to 70%, high arterial carbon dioxide tension (greater than or equal to 60 mm of Hg) was associated with greater overestimation of SaO2.
Animals↗
Localization of myomodulin-like immunoreactivity in the central nervous system and peripheral tissues of Aplysia californica.
The distribution of myomodulin-like peptides in the nervous system of Aplysia californica was examined by using immunocytochemical techniques. Neurons and cell clusters containing immunoreactive material were located in each of the major central ganglia. Myomodulin-like immunoreactivity was also present in fibers in each of the connectives between the ganglia and in peripheral nerves. Varicosities containing immunoreactive material were located on specific regions of peripheral tissues associated with the feeding, digestive, cardiovascular, and reproductive systems. Double-labeling experiments were used to demonstrate myomodulin-like immunoreactivity in two identified neurons, the motor neuron B16 in the buccal ganglion and the widely acting interneuron L10 in the abdominal ganglion. Structures in the eye and cerebral ganglion that may correspond to the optic circadian pacemaker system were also stained. The central and peripheral distribution of myomodulin-like immunoreactivity indicates that this family of neuropeptides is present in specific efferent, afferent, and interneuronal elements that participate in a diversity of neural circuits in Aplysia.
Amino Acid Sequence↗
Expression of ALZ-50 immunoreactivity in the developing principal sensory nucleus of the trigeminal nerve: effect of transecting the infraorbital nerve.
Many neurons in the CNS die as a consequence of normal development. As these neurons die, they may be programmed to produce 'death proteins'. We explored the possibility that an antigen recognized by ALZ-50, a protein expressed in Alzheimer's-type neurofibrillary tangles, is generated during the process of neuronal death. The effects of transecting the infraorbital nerve on the expression of ALZ-50 immunoreactivity and neuronal death in the principal sensory nucleus of the trigeminal nerve (PSN) was examined. In normal rats, a small number of PSN neurons was ALZ-50-positive on postnatal day (P) 3. Transections on the day of birth (i.e. during the period of naturally occurring neuronal death) led to a 5-fold increase in the number of immunoreactive neurons expressing a 56-kDa protein on P3. In contrast, lesions on P25 (i.e. after the period of naturally occurring neuronal death) did not induce any neurons to exhibit ALZ-50 immunoreactivity. Thus, the 56-kDa protein recognized by ALZ-50 appears to be a death protein which is transiently expressed during the period of naturally occurring neuronal death. It is appealing to speculate that the pathological degeneration described in Alzheimer's brains results from the up-regulation of a quiescent developmental program.
Animals↗
Birthdates of trigeminal ganglion cells contributing axons to the infraorbital nerve and specific vibrissal follicles in the rat.
Prenatal labelling with [3H]-thymidine was combined with retrograde tracing techniques in adult rats to determine the birthdates of the trigeminal (V) ganglion cells that contributed axons to the infraorbital nerve (ION) and the generation of the subsets of ION cells that innervated specific vibrissae follicles (C-1 and C-5). The V ganglion cells contributing axons to the ION are born between embryonic (E-, E-0 = the day of conception) days 9.5 and 14.5. The percentages (normalized so that they total 100%) of the total V ganglion population born on E-9.5 through E-14.5 were 5.8, 25.7, 19.8, 23.4, 21.0, and 4.4%, respectively. The distribution of birthdates for the V ganglion cells that were retrogradely labelled from the ION closely matched that for the ganglion as a whole. All of these neurons were also born on E-9.5 through E-14.5, and the percentages born on each day were 6.3, 23.6, 18.1, 24.0, 23.6, and 4.4%. Finally, a similar distribution of birthdates was obtained for the V ganglion cells that were retrogradely labelled after injection of retrograde tracers into either the C-1 or C-5 vibrissae follicles. We were unable to detect any distinctive spatial distributions for either all V ganglion or ION cells born on a specific embryonic day. Furthermore, neurons with a given birthdate and that innervated a given follicle were distributed throughout the entire region containing all of the ganglion cells supplying the follicle in question. Therefore, it appears that the V ganglion cells contributing axons to the ION are born over the entire period of ganglion neurogenesis and further that the organization of the ION's innervation of the periphery is not a function of cell birthdate.
Animals↗
Chylothorax in cats: 37 cases (1969-1989).
Case records of 37 cats with chylothorax examined at 2 institutions were retrospectively evaluated. Dyspnea and coughing were the most common abnormalities noticed by the owners, and most cats were dyspneic on initial examination. There was no statistically significant difference in the gender distribution of cats studied when compared with reference populations; however, purebred cats appeared to be overrepresented in the study population. Four of the cats had unilateral pleural effusion (2 left side, 2 right side) and 9 cats had effusions that were primarily, but not exclusively, on the right side. Surgery was performed on 20 cats. Fifteen cats underwent thoracic duct or cisterna chyli ligation; 20% had complete resolution of pleural fluid. There was no significant difference in the survival rate of cats that underwent thoracic duct ligation and those that were treated by other means. Six cats had mesenteric lymphangiography performed; 2 cats had normal results, and the remainder had various degrees of thoracic lymphangiectasia. Two cats in which pleuroperitoneal shunts were placed and 2 of 3 cats that underwent pleurodesis were euthanatized or died after surgery.
Age Factors↗
Failure to reproduce increased calcium uptake in human lymphocytes at purported cyclotron resonance exposure conditions.
An attempt was made to verify a report (Liboff et al. 1987) that a unique combination of DC and AC magnetic field exposures at room temperature results in a 3-fold increase in 45Ca2+ uptake by human lymphocytes in vitro. Exposures at "resonance condition", as well as at frequencies and amplitudes above and below the reported effective exposure conditions, were without effect, as were exposures at 37 degrees C. Treatment with ionomycin (0.25 microM), a positive control, resulted in a highly significant increase 45Ca2+ uptake. Some experiments were performed simultaneously by different investigators. Their results did not differ significantly. All experiments were conducted "double blindly".
Analysis of Variance↗
Lack of increase in cell transformation frequency of C3H cells after exposure to pulsed ultrasound.
Liebeskind et al. reported that ultrasound from a diagnostic ultrasound unit caused an increase in cell transformation of in vitro C3H cells. The objective of this study was to attempt verification of this result, using the same cell line and a similar ultrasound exposure regimen. Four experiments were undertaken, each involving an ultrasound, X-ray (positive control) and sham exposure regimen. There was no increase in cell transformation frequency with the ultrasound exposure, but a small and statistically significant increase with the X-ray regimen.
Animals↗
The use of frequency mixing to distinguish size distributions of gas-filled micropores.
The presence of difference frequencies produced by frequency mixing from the nonlinear resonance of gas bodies has been employed to detect gas in porous hydrophobic membranes and to distinguish between gas bodies in the membranes with pore sizes. Calculations based on measured pore sizes were used to predict the range of frequencies over which resonance may be expected and also to predict that the two different nominal pore sizes in this study would have distinguishable resonance characteristics. Measurements of porous and nonporous membrane scattering characteristics before and after membrane pressurization and measurements of receiver linearity indicate that resonance of the gas bodies in the membranes is the origin of the observed difference-frequency amplitudes. Difference-frequency amplitudes in the spectra of signals scattered from the membranes with smaller pores are found to peak at excitation frequencies higher than difference-frequency amplitudes produced by membranes with larger pores and generally follow the predictions of the calculations. The results show that a two-frequency mixing technique is capable of detecting and distinguishing sizes of gas bodies that may exist in vivo and serve as cavitation nuclei.
Gases↗
Lack of induced increase in sister chromatid exchanges in human lymphocytes exposed to in vivo therapeutic ultrasound.
In 1984 Stella et al. reported that each of 10 patients exposed to therapeutic ultrasound had a statistically significant increase in sister chromatid exchanges (SCEs) at mid- and end of therapy; there was a wide range of clinical symptoms (e.g., elbow epicondylitis to knee arthrosis) in this set of patients. In the present study, a set of 4 patients each with some diagnosis recommending therapeutic ultrasound was similarly tested for SCE induction; an additional set of 4 healthy persons underwent sham-therapeutic ultrasound exposures. For both sets of subjects (patients, nonpatients) there was no increase in the frequency of SCEs.
Adult↗
Effect of prenatal exposure to ethanol on the cell cycle kinetics and growth fraction in the proliferative zones of fetal rat cerebral cortex.
Prenatal exposure to ethanol produces profound changes in the number of neurons in the mature cortex. These changes in neuronal number may reflect ethanol-induced disturbances in early developmental processes, that is in the proliferation of neuronal precursors. Hence, the present study examined the effect of ethanol on cell proliferation in the two neocortical proliferative zones, the ventricular zone (VZ) and subventricular zone (SZ). From gestational day 5 to 21, pregnant rats were fed an ethanol diet (6.7% v/v), pair-fed an isocaloric control diet, or fed chow and water. Pregnant rats were given a series of one to nine injections of bromodeoxyuridine (BrdU). After immunohistochemical processing, the ratio of cells in each proliferative zone that were labeled with BrdU to the total population was determined. The portion of the population that was cycling (growth fraction), the total length of the cell cycle, and the length of the S-phase of the cell cycle were calculated for VZ and SZ cells. Exposure to moderate levels of ethanol has markedly different effects upon the two neocortical proliferative zones. In the VZ, the length of the total cell cycle was significantly greater in ethanol-treated rats than in controls; however, the growth fraction and the length of the S-phase were unaffected by ethanol. In contrast, in the SZ, the growth fraction was significantly greater in ethanol-treated rats, but ethanol had no effect on the length of the total cell cycle or of the S-phase. These differences may underlie the ethanol-induced abnormalities in neuronal generation.
Animals↗
Detecting nonhemolytic Pasteurella haemolytica infections in healthy Rocky Mountain bighorn sheep (Ovis canadensis canadensis): influences of sample site and handling.
Effects of sampling procedures on ability to culture Pasteurella spp. from Rocky Mountain bighorn sheep (Ovis canadensis canadensis) were examined experimentally. Sample site influenced (P less than 0.0001) recovery of P. haemolytica in adult bighorn sheep. We isolated nonhemolytic P. haemolytica from 18 of 19 tonsillar swabs and 18 of 19 tonsillar biopsies from adult sheep, yet only four of 19 nasal swabs yielded isolates. Sample handling also affected (P less than 0.0001) recovery of P. haemolytica. Nonhemolytic P. haemolytica was cultured from 14 of 19 tonsillar swabs plated directly onto blood agar, but from only two of 19 swabs stored for 24 hr in modified Stuart's medium. We detected nonhemolytic P. haemolytica at least once in bronchial aspirates from four and in nasal swabs from three of six bighorn lambs. Based on direct cultures of tonsillar swabs and/or biopsies, all 26 bighorn sheep (seven lambs, 19 adults) sampled were infected with nonhemolytic P. haemolytica; only two lambs developed pneumonia during the study period. Thirty-four of 37 nonhemolytic P. haemolytica isolates tested were biotype T; three were biotype A. Serotypes 3; 4; 3, 4 and 3, 4, 10 were identified in a subsample of 17 isolates. Our data suggest tonsillar swabs or biopsies plated directly onto blood agar and incubated immediately offer the greatest probability of recovering nonhemolytic P. haemolytica from health bighorn sheep.
Animals↗
Spontaneous pasteurellosis in captive Rocky Mountain bighorn sheep (Ovis canadensis canadensis): clinical, laboratory, and epizootiological observations.
We observed clinical signs, compared adrenal responses, and performed diagnostic tests on 12 captive Rocky Mountain bighorn sheep (Ovis canadensis canadensis) during a spontaneous outbreak of pasteurellosis. Cortisol in urine and feces was measured for bighorns sampled three times between 20 October and 1 November 1986. By 6 November, four of these had developed pneumonia, four showed only mild rhinitis, and four remained clinically normal. Bighorns that ultimately developed pneumonia showed elevated mean urinary (P = 0.003) and fecal (P = 0.046) cortisol excretion over the 12-day sampling period. Twenty-four hour mean urine cortisol: creatinine ratios ranged from 10 to 57 ng/mg dry matter for affected and 5 to 22 ng/mg for healthy individuals; 24 hr mean fecal cortisol concentrations ranged from 7.2 to 20 ng/g dry matter for affected and 3.6 to 9.1 ng/g dry matter for healthy individuals. Elevated cortisol excretion preceded clinical pneumonia in affected bighorns by less than or equal to 16 days. Beta-hemolytic Pasteurella haemolytica biotype T, serotype 3 or 4, was isolated from nasal and pharyngeal swabs from all eight bighorns with pneumonia or mild rhinitis. We detected no evidence of parainfluenza 3, bovine respiratory syncytial virus, or Chlamydia psittaci using fluorescent antibody and/or serologic tests. Although elevated cortisol excretion was associated with pneumonia, we also believe age, reproductive physiology, and/or prior recovery from clinical pasteurellosis may have influenced individual susceptibility to pneumonia during this epizootic.
Animals↗
Identification and characterization of cerebral-to-buccal interneurons implicated in the control of motor programs associated with feeding in Aplysia.
We identified candidate neurons in the cerebral ganglion that regulate feeding responses mediated by the buccal ganglion. Backfilling the cerebral-buccal connectives revealed that each cerebral hemi-ganglion contains approximately 20 neurons that project axons to the buccal ganglion. Three M-cluster neurons (CBI-1, CBI-2, CBI-3) and one E-cluster neuron (CBI-4) were identified as cerebral-to-buccal interneurons (CBIs) based on position, morphology, synaptic connections, and ability to drive buccal motor programs (BMPs). CBI-1 responds to touch of the tentacles, lips, and buccal mass. It receives monosynaptic EPSPs from interganglionic, cerebral-to-buccal mechanoafferent (ICBM) neurons and monosynaptically excites buccal cells, some of which are also excited by the ICBMs. Tonic firing of CBI-1 usually evokes a single cycle of BMP activity. CBI-1 phase-shifts the rhythmic BMP driven by firing a dopaminergic neuron in the buccal ganglion. CBI-1 itself exhibits dopamine-like histofluorescence following formaldehyde-glutaraldehyde fixation. CBI-2 is excited by food stimuli applied to the lips. Constant-current intracellular stimulation of CBI-2 produces phasic firing of the cell that reliably evokes a rhythmic BMP that incorporates buccal and cerebral motor neurons, putative pattern-generating and pattern-initiating neurons, and neuromodulatory cells (metacerebral cells). CBI-4 also evokes a rhythmic BMP, but the details of its actions and synaptic effects differ from that of CBI-2. CBI-3 does not evoke a BMP, even though it is excited by food stimuli applied to the lips, and it makes monosynaptic connections (both excitatory and inhibitory) to many follower cells of the other CBIs. Firing of CBI-3 phase-delays the BMP driven by CBI-2. Since its activity is incorporated into BMPs and it provides direct inputs to elements of the feeding circuitry, it may play a role in pattern generation. The distinctive features of the CBIs suggest that the consummatory phase of feeding may be controlled by a population of interneurons that subserve different roles.
Animals↗