Confirmation of tracheal intubation in a neonate using the Fenem CO2 detector.
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Breath Tests↗
Biomedical subjects
D Higgins
Publications and source records attributed to D Higgins.
Seroepidemiology of Q fever among cats in New Brunswick and Prince Edward Island.
The indirect microimmunofluorescence test was used to determine the presence of antibodies to phase I and phase II Coxiella burnetii antigens in New Brunswick and Prince Edward Island cats. Twenty of 104 (19.2%) New Brunswick cats tested had antibodies to phase II antigen; five of these (4.8%) also had antibodies to phase I antigen. Six of 97 (6.2%) Prince Edward Island cats tested had antibodies to phase I and phase II antigens. Our data suggest that cats may be important in the epidemiology of Q fever in these provinces.
Animals↗
Astrocytes induce dendritic development in cultured sympathetic neurons.
Sympathetic neurons in culture require the influence of Schwann cells in order to develop dendrites comparable to those seen in vivo. This study demonstrates that astrocytes induce dendritic development in greater than 90% of sympathetic neurons after two weeks of co-culture. We conclude that dendrite inducing factors are distributed on both central and peripheral glia.
Animals↗
Age-dependent changes in the capacity of rat sympathetic neurons to form dendrites in tissue culture.
We compared the ability of prenatal and postnatal rat sympathetic neurons to form dendrites in tissue culture. Dendrites were distinguished from axons by light microscopic criteria after intracellular dye injection and by differential immunostaining with antibodies to microtubule-associated protein-2 and to both non-phosphorylated and phosphorylated forms of the M and H neurofilament subunits. When maintained in the absence of serum and non-neuronal cells, most (72%) prenatal neurons were unipolar and had only an axon. In contrast, most (89%) neurons derived from postnatal ganglia were multipolar and extended both axons and dendrites. The dendritic morphology of postnatal neurons was usually simple with cells commonly having 2-5 short (50-200 microns), relatively unbranched dendrites. Thus, as the development of the dendritic arbor progresses in situ, sympathetic neurons acquire an enhanced ability to extend dendrites in tissue culture. To determine whether changes in the capacity to develop dendrites might occur with aging in vitro, ganglia were removed from prenatal rats and grown as explants for 3 weeks in the presence of non-neuronal cells; under these conditions, prenatal neurons within the explant became multipolar. When neurons derived from aged explants were subsequently maintained in dissociated cell culture, most formed dendrites. In cultures treated with an antimitotic agent, neurons typically had 1-4 unbranched dendrites; greater amounts of dendritic growth occurred in cultures in which ganglionic non-neuronal cells were allowed to proliferate. We conclude that: (1) the acquisition of the capacity to form dendrites in dissociated cell culture does not require either normal afferent input or physical contact with the target tissue; and (2) even after aging in vitro, sympathetic neurons remain responsive to the dendrite-promoting activity of ganglionic non-neuronal cells.
Adrenergic Fibers↗
Laminin and a basement membrane extract have different effects on axonal and dendritic outgrowth from embryonic rat sympathetic neurons in vitro.
We have characterized the effects of laminin and a basement membrane extract (BME) on the morphology of embryonic rat sympathetic neurons maintained in tissue culture in the absence of nonneuronal cells. Neurons were grown on polylysine-coated coverslips in the presence or absence of laminin or BME in serum-free medium. Axons were distinguished from dendrites using intracellular dye injections, immunocytochemistry, and [3H]uridine autoradiography. In short-term (less than or equal to 24 hr) culture, laminin had a potent neurite-promoting effect, causing increases in the number of processes, total neuritic length, and neuritic branching. In long-term (3-35 days) cultures chronically exposed to laminin, most (greater than 75%) neurons maintained supernumerary axons but failed to form dendrites. In contrast, most neurons (greater than 70%) grown in long-term culture on polylysine in the absence of laminin were unipolar, extending a single axon. BME caused sympathetic neurons to extend multiple (range, 1-15) dendrites. Morphometric measurements made after 1 month of exposure to BME indicated that the amount of dendritic growth that occurred in vitro was similar to that normally occurring during a comparable period in situ. BME did not cause changes in the number of axons per neuron or in the uptake of neurotransmitter. Preliminary characterization of the dendrite-promoting activity of BME suggests that it resides in extracellular matrix (ECM) molecules and not in low-molecular weight contaminants. These observations indicate that (1) axonal and dendritic growth may be differentially regulated by various constituents of the ECM, and (2) such process-specific interactions can significantly affect the morphological development of sympathetic neurons.
Animals↗
Project SENSOR: occupational disease and injury surveillance.
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Accidents, Occupational↗
Glial cells promote dendritic development in rat sympathetic neurons in vitro.
Many types of glial-neuronal interactions occur during the development of the nervous system. To determine how such interactions might affect the development of autonomic ganglia, we compared the morphology of embryonic rat sympathetic neurons grown in the absence and in the presence of ganglionic nonneuronal cells in serum-free medium. Dye injections, electron microscopy, and immunocytochemistry were used to distinguish axons from dendrites. In cultures without nonneuronal cells, most (greater than 80%) sympathetic neurons extended only a single axonal process, and this unipolar state persisted for at least 8 weeks. Coculture with ganglionic nonneuronal cells caused sympathetic neurons to become multipolar and to extend multiple (range 1-17) dendrites. Morphometric measurements made after 1 month of coculture indicated that the amount of dendritic growth that occurred in vitro (mean number of dendrites/cell = 7.5; total dendritic length = 1,050 micron) was similar to that normally occurring during a comparable period in situ. In contrast to its prominent effects on dendritic growth, coculture did not cause changes in the number of axons/neuron or in the uptake of neurotransmitter. Cultures with ganglionic nonneuronal cells were immunostained for antigens present on the surfaces of fibroblasts (Thy-1.1, fibronectin) and of glia of the peripheral nervous system (laminin). Fewer than 1% of the nonneuronal cells displayed immunoreactivity for fibroblastic antigens; in contrast, greater than or equal to 99% reacted with antibody to laminin. Moreover, reconstitution experiments revealed that purified populations of laminin-positive Schwann cells promoted dendritic growth. Fibroblasts and heart cells lacked this activity. These data indicate that glia selectively promote dendritic development in sympathetic neurons maintained in serum-free medium.
Animals↗
Mutation of lysine-48 to arginine in the yeast RAD3 protein abolishes its ATPase and DNA helicase activities but not the ability to bind ATP.
The RAD3 gene of Saccharomyces cerevisiae is required for excision repair of DNA damaged by UV radiation and is also essential for cell viability. The approximately 89 kd protein encoded by RAD3 possesses single-stranded DNA dependent ATPase and DNA helicase activities. The sequence Gly-X-Gly-Lys-Thr, believed to be involved in the interaction with purine nucleotides in proteins that bind and hydrolyze the nucleotides, is present in the RAD3 primary structure between amino acids 45 and 49. We report here that the point mutation of Lys-48 to arginine abolishes the RAD3 ATPase and DNA helicase activities but not the ability to bind ATP. These observations highlight the involvement of this lysine residue in the hydrolysis of ATP and indicate that the positive charge on arginine can replace that of the lysine residue in the binding of ATP but not in its hydrolysis. The rad3 Arg-48 mutant is apparently defective in a step subsequent to incision at the damage site in DNA; it can incise UV damaged DNA, but does not remove pyrimidine dimers. The role of the ATPase and DNA helicase activities of the RAD3 protein in its DNA repair and viability functions is discussed.
Adenosine Triphosphatases↗
Morphological differentiation of embryonic rat sympathetic neurons in tissue culture. I. Conditions under which neurons form axons but not dendrites.
We have examined the morphology of fetal rat sympathetic neurons grown in serum-free medium in the absence of nonneuronal cells. Because cell density can affect phenotypic expression in vitro, the morphological analysis was subdivided into the study of isolated neurons (neurons whose somata were at least 150 micron from their nearest neighbor) and of more highly aggregated neurons. When isolated neurons were injected with intracellular markers, it was found that most (79%) had a single process emanating from their somata and that this unipolar state persisted for at least 8 weeks in vitro. The processes of unipolar sympathetic neurons had the appearance of axons in that they were thin and long, had a constant diameter, and were relatively unbranched. Cytochemical methods revealed that such processes had other axonal characteristics: (1) they were more reactive with a monoclonal antibody against phosphorylated forms of the M and H neurofilament subunits than with an antibody to nonphosphorylated forms of these proteins; (2) they also reacted with antibodies to the tau microtubule-associated protein and to the phosphorylated forms of the H neurofilament subunit; and (3) they contained only small amounts of RNA as determined by [3H]uridine autoradiography. These data indicate that neurons which normally form dendrites in vivo need not express this capacity in vitro and that axonal and dendritic growth can be dissociated under some conditions in culture. While most isolated neurons were unipolar, neurons in regions of high neuronal cell density were usually multipolar. In addition to axons, multipolar neurons had processes with some of the characteristics expected of rudimentary dendrites: they ended locally (usually within 100 micron), were often highly branched, and reacted with an antibody to nonphosphorylated forms of the M and H neurofilament subunits. The effects of density were most prominent when neurons were within aggregates in which the somata were in close apposition. Density-dependent changes in morphology were less frequently observed when neuronal somata were separated by greater distances (30-100 micron). These data indicate that the morphology of sympathetic neurons is subject to environmental regulation and that neuron-neuron interactions can promote the extension of rudimentary dendrites in vitro.
Animals↗
Morphological differentiation of embryonic rat sympathetic neurons in tissue culture. II. Serum promotes dendritic growth.
In the preceding paper, we reported that embryonic rat sympathetic neurons formed axons, but not dendrites, when they were maintained in the absence of serum and nonneuronal cells. To assess the effects of serum-derived factors on cellular morphology, cultures were initially maintained in serum-free medium while nonneuronal cells were eliminated. Subsequently some cultures were chronically exposed either to fetal calf serum (10%) or to a high-molecular-weight ammonium sulfate fraction of serum (P40 material, 500 micrograms/ml). Phase-contrast microscopy revealed that serum and P40 material did not alter neuronal survival, but did cause flattening of the somata and fasciculation of processes. When neurons exposed to serum or P40 material were injected with Lucifer Yellow, it was found that the majority (greater than or equal to 90%) had local, tapered processes that could be identified as dendrites by light microscopic criteria. These local processes also exhibited other dendritic characteristics in that (1) they reacted with monoclonal antibodies to nonphosphorylated forms of the M and H neurofilament subunits and to microtubule-associated protein 2; and (2) they had substantial amounts of RNA as determined by [3H]uridine autoradiography. Quantitative measurements of the effects of serum and P40 material on dendritic morphology revealed that (1) an 8-day exposure caused most neurons (greater than 80%) to form dendrites; (2) neurons typically had more than one dendrite (mean of 4.1 +/- 0.2 dendrites/cell after a 28-day exposure); and (3) the dendrites were relatively short with the maximum extent of the dendritic arbor being 110 +/- 13 micron after 4 weeks. Serum and P40 material did not routinely cause the formation of supernumerary axons, did not alter radial axonal outgrowth from ganglion explants, and did not significantly increase [3H]leucine incorporation. Thus, serum contains a factor (or factors) which selectively stimulates the extension of dendrites, but not axons. If such a factor were operative in situ, it could play an important role in determining the morphology of sympathetic neurons. In examining the mechanism of serum-induced dendritic growth, we found that even high concentrations (5 micrograms/ml) of nerve growth factor failed to promote dendritic growth in the absence of serum; thus, nerve growth factor by itself is not a sufficient condition for the extension of dendrites.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
The distribution of microtubule-associated protein 2 changes when dendritic growth is induced in rat sympathetic neurons in vitro.
We have examined the distribution of microtubule-associated protein 2 in embryonic rat sympathetic neurons grown under culture conditions that alter morphological development. Cultures were established in serum-free medium. After 8 days some were transferred to a serum-containing medium, which promotes dendritic development. Sister cultures were maintained in serum-free medium, which inhibits dendritic growth but permits normal axonal development. After growth for 2-6 weeks in serum-containing medium, sympathetic neurons were multipolar, with short, tapering dendrites and long, thin axons. Intense immunoreactivity for microtubule-associated protein 2 was observed in the somata and dendrites of all neurons, but there was little or no staining of the network of axonal processes that ran between cell somata. When the morphology of individual cells was assessed by injection of fluorescent dye before immunostaining, we found that staining for microtubule-associated protein 2 extended to the distal tips of the dendrites while the axon was essentially unstained, even in its proximal portion. Neurons from sister cultures that were not exposed to serum were usually unipolar, having only an axon. Under these conditions microtubule-associated protein 2 was also expressed, but its distribution was altered: intense immunostaining for microtubule-associated protein 2 was present in axons as well as somata. Staining in axons could sometimes be traced for several millimeters, but, since unstained segments of axons were also common, microtubule-associated protein 2 probably was not present throughout the entire axonal arborization. These results show that the expression of microtubule-associated protein 2 is not of itself sufficient to induce the formation of dendrites. Despite the association of microtubule-associated protein 2 with the axonal cytoskeleton, the light microscopic morphology of the axons was not obviously altered.
Animals↗
Chronic treatment with bromocriptine induces behavioral supersensitivity in rats.
Chronic treatment of rotating rats with equipotent doses of the dopamine (DA) agonists apomorphine (APO), 3-(3,4-dihydroxyphenyl)-1-n-propylpyrrolidine hydrobromide (DPPP) and bromocriptine (BRO) for four weeks resulted in marked differences in rotational activity following acute administration of these agonists. Whereas chronic treatment with APO and DPPP failed to produce any significant changes in agonist-induced rotational behavior, chronic BRO treatment induced a progressive increase in rotational activity up to a mean 200% increase over controls at four weeks. These findings may, in part, explain the long-term clinical efficacy of bromocriptine in patients with Parkinson's disease.
Animals↗
Factors associated with the biochemical changes in vitamin D and calcium metabolism in institutionalized patients with epilepsy.
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Adolescent↗
Pharmacologic evaluation of dopaminergic receptor blockade by metoclopramide.
The occurrence of adverse extrapyramidal effects following metoclopramide (MCP) therapy has been well documented in humans. In rats, MCP produced catalepsy and inhibited apomorphine-induced stereotypy, locomotor activity, and rotational behavior. MCP also accelerated dopamine turnover, potently stimulated prolactin release, and, at high concentrations, inhibited [3H]spiperone binding to striatal membranes. These behavioral and biochemical effects induced by MCP were similar to those observed with haloperidol. We conclude that MCP possesses most of the pharmacological properties of neuroleptic agents.
Animals↗
Joint ventures revisited: we're all in this together.
Healthcare organizations are finding it advantageous, and in some cases necessary, to join together to offer new services, seek economies of scale, or just stay in business. These partnerships can take various forms including joint ventures, shared service agreements, or multiprovider arrangements. together, they represent new approaches to operating more efficiently and effectively in a changing healthcare industry. This article marks the beginning of a three-part series on the joint venture in health care. The series explores possible joint venture models, explains the legal implications in setting up a joint venture, and shows how to evaluate a potential deal. Together they provide a background and a starting point for the financial manager considering the possibility of a joint venture.
Commerce↗
Joint ventures in health care: more than a sideline business.
Many times, healthcare joint ventures are considered second class, sideline businesses, and consequently, are not viewed as complex business relationships. However, compared to other small enterprises, the joint venture presents a complex list of legal and practical issues that must be understood and resolved. Such issues as organizational form, antitrust, reimbursement, licensing, and securities laws must be considered to ensure a successful joint venture.
Economic Competition↗
Joint ventures in health care: what to do before you do the deal.
To be successful, a hospital-physician joint venture must be guided by a strategy that includes a coherent business strategy, an orientation to the specific needs of the potential physician participants, a bias towards closure, and a rigorous process for evaluating, structuring, and implementing transactions. This article focuses on the last characteristic of the strategy--a process for evaluation, structuring, and implementation. Such a process will establish the basic viability of the project, give direction to the approach, provide a fundamental understanding of the transaction, and create an overall businesslike attitude.
Capital Financing↗
Hemodynamics of human arterial stenoses.
We assessed the hemodynamic and geometric changes in compliant, human arterial stenoses in response to manipulation of vascular tone, perfusion pressure and distal resistance. Coronary and popliteal arteries were harvested from human cadavers shortly after death. Following incubation for several hours to permit recovery of physiologic energy stores and ion gradients, the vessels were attached to a perfusion apparatus and perfusion pressure (PP), distal pressure (DP), and flow (F) were recorded as perfusion pressure and distal resistance (DR) were varied. The experiments were then repeated in the presence of a vasoconstrictor (100 mM KCl). Orthogonal arteriograms were performed at maximums of vasoconstriction and vasodilation. Stenotic resistance (SR) was calculated as (PP-DP)F. Minimum cross-sectional area was determined by computer assisted analysis of the arteriograms. Stenosed vessels with normal wall segments at the stenosis responded to vasoconstriction with a large stenotic resistance increase (111 +/- 15%; P less than 0.05) and a flow decrease averaging 39.3 +/- 6.2% (P less than 0.05). In addition, decreased perfusion pressure also increased stenotic resistance significantly (P less than 0.05). Stenotic resistance changes were of sufficient magnitude to be both statistically significant and clinically important. These results confirm the existence of dynamic arterial stenoses in humans and further support the assertion that dynamic stenotic severity changes elicited by manipulation of proximal and distal vascular tone and pressure are of sufficient magnitude to create acute ischemia. This information may apply to clinical situations in which compliant stenoses and acute ischemia coexist.
Aged↗