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M McPheeters

Publications and source records attributed to M McPheeters.

11 recordsLinked to original sources
PubMed2001

Maintenance of rat taste buds in primary culture.

The differentiated taste bud is a complex end organ consisting of multiple cell types with various morphological, immunocytochemical and electrophysiological characteristics. Individual taste cells have a limited lifespan and are regularly replaced by a proliferative basal cell population. The specific factors contributing to the maintenance of a differentiated taste bud are largely unknown. Supporting isolated taste buds in culture would allow controlled investigation of factors relevant to taste bud survival. Here we describe the culture and maintenance of isolated rat taste buds at room temperature and at 37 degrees C. Differentiated taste buds can be sustained for up to 14 days at room temperature and for 3-4 days at 37 degrees C. Over these periods individual cells within the cultured buds maintain an elongated morphology. Further, the taste cells remain electrically excitable and retain various proteins indicative of a differentiated phenotype. Despite the apparent health of differentiated taste cells, cell division occurs for only a short period following plating, suggesting that proliferating cells in the taste bud are quickly affected by isolation and culture.

Animals↗
PubMed1998

A basolateral chloride conductance in rat lingual epithelium.

We used Ussing chamber measurements and whole-cell recordings to characterize a chloride conductance in rat lingual epithelium. Niflumic acid (NFA) and flufenamic acid (FFA), nonsteroidal anti-inflammatory aromatic compounds known to inhibit Cl- conductances in other tissues, reduced transepithelial short-circuit current (Isc) in the intact dorsal anterior rat tongue epithelium when added from the serosal side, and reduced whole-cell currents in rat fungiform taste cells. In both Ussing chamber and patch-clamp experiments, the effect of NFA was mimicked by replacement of bath Cl- with methanesulfonate or gluconate. In low Cl- bath solution, the effect of NFA on whole-cell current was reduced. Replacement of bath Ca2+ with Ba2+ reduced the whole-cell Cl- current. We conclude that a Ca2+-activated Cl- conductance is likely present in the basolateral membrane of the rat lingual epithelium, and is present in the taste receptor cells from fungiform papillae. Further experiments will be required to identify the role of this conductance in taste transduction.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1998

The prevalence of homelessness among adolescents in the United States.

OBJECTIVES: Homeless adolescents represent one of the nation's most vulnerable populations. This study reports the 12-month prevalence of homeless episodes among US adolescents. METHODS: Personal, audiotaped interviews were conducted in 1992 and 1993 with a representative household sample of 6496 adolescents aged 12 to 17 as part of the Youth Risk behavior Survey sponsored by the Centers for Disease Control and Prevention. Respondents reported whether they had spent the night in any of a variety of locations other than home during the previous 12 months. RESULTS: Altogether, 7.6% of the youths questioned reported that they had spent at least 1 night in youth or adult shelter (3.3%), public place (2.2%), an abandoned building (1.0%), outside 2.2%), underground (0.4%), or with a stranger (1.1%). Boys were much more likely than girls to report having experienced a homeless episode. CONCLUSIONS: This study suggests that homelessness among adolescents is not simply an urban problem and that prevention programs targeting homeless youths should be implemented nationwide. Additional research is needed to assess the frequency and duration of homeless experiences. Future studies of homelessness in the general population should include questions pertinent to adolescents.

Adolescent↗
PubMed1997

Development of membrane properties in taste cells of fungiform papillae: functional evidence for early presence of amiloride-sensitive sodium channels.

Behavioral and physiological studies have demonstrated a reduced sensitivity to several taste stimuli early in development. It has been suggested that this reduced sensitivity results from a late maturation of underlying transduction mechanisms. Little is known, however, about maturation of membrane properties of taste cells early in development. We have obtained whole-cell recordings from single fungiform taste cells of rat pups to examine the development of the NaCl transduction system. Although taste buds undergo a considerable increase in size during development, membrane capacitance measurements revealed no change in membrane surface area of individual taste cells, suggesting that the increase in size results from an increase in the total number of cells per bud. Whole-cell recordings showed that taste cells from very young pups [postnatal day 2 (PND2)] already possessed voltage-activated Na+ and K+ currents with no apparent differences in size or kinetics compared with adults. Surprisingly, amiloride-sensitive Na+ responses, important for Na+ transduction, were found as early as PND2. The magnitude of responses to amiloride and the percentage of amiloride-sensitive cells remained the same throughout all age groups. Furthermore, the similarity of amiloride inhibition constants suggested that the channel in neonates is the same channel that is expressed in adult taste buds. Our results indicate that taste cells at PND2 already have acquired the transduction elements necessary for signaling NaCl responses to the afferent nerve. We hypothesize that complete functionality of the salt taste transduction system, however, may not be reached until amiloride-sensitive Na+ channels become selectively localized at the apical membrane. This would explain previous studies indicating that amiloride sensitivity cannot be detected before PND12 in the intact tongue. Apical clustering of channels along with the opening of the taste pore and an increase in the total number of taste cells per bud likely constitute additional important steps toward a fully functional sensory system.

Amiloride↗
PubMed1996

Intrauterine devices: learning from the past and looking to the future.

This paper reviews the historical development of the IUD, describing the challenges and successes, and attempts to offer a balanced perspective for family planning service workers today. Modern IUDs are an important component of family planning services and an excellent contraceptive choice for properly screened women, providing contraception that is safe, effective, long lasting and cost effective. Potential research strategies for the future are also discussed.

Family Planning Services↗
PubMed1995

A review of safety, efficacy, pros and cons, and issues of puerperal tubal sterilization--an update.

This review focuses on the safety, efficacy, pros and cons of tubal sterilization procedures performed during the puerperium period while the woman is still in hospital. Findings from four previous reviews are synthesized, and the results published in more recent literature are evaluated. The review finds that tubal sterilization performed while the woman is still on the delivery table, or during a woman's early puerperium while she remains hospitalized, is operationally easy and medically safe, and does not adversely affect lactation. However, reported pregnancy rates are generally higher in puerperal tubal sterilization than in interval sterilization, especially when the mechanical tubal occlusion technique is used. The Pomeroy method, and its modifications via minilaparotomy, is highly recommendable. On the other hand, electrocoagulation via laparoscopy is associated with high efficacy, but a potentially increased risk of complications and difficulties in tubal reversal. Tubal sterilizations can be easily and safely performed at cesarean delivery in selected cases. Tubal sterilization performed during puerperium has a number of advantages over short-acting contraceptive methods, which require strict compliance, for postpartum use. However, candidates for puerperal tubal sterilization need to be carefully screened and counseled, since post-sterilization regret is more likely to occur. Unsettled issues for puerperal tubal sterilization and a number of practical problems that need to be addressed before initiation of a puerperal tubal sterilization program in a maternity clinic/hospital are discussed.

Female↗
PubMed1994

Electrophysiological and morphological properties of light and dark cells isolated from mudpuppy taste buds.

Isolated Necturus taste receptor cells were studied by giga-seal whole-cell recording and electron microscopy to correlate electrophysiological properties with taste cell structural features. Dark (type I) cells were identified by the presence of dense granular packets in the supranuclear and apical regions of the cytoplasm. In response to a series of depolarizing voltage commands from a holding potential of -80 mV, these cells exhibited a transient, TTX-sensitive inward Na+ current, a sustained outward K+ current, and a slowly inactivating inward Ca++ current. Light (type II) cells were identified by a lack of granular packets and by an abundance of smooth endoplasmic reticulum distributed throughout the cell. In addition, isolated light cells had clear vesicular inclusions in the cytoplasm and blebs on the plasma membrane. Light cells were divided into two functional populations based upon electrophysiological criteria: cells with inward and outward currents, and cells with outward currents only. Light cells with inward and outward currents had voltage-activated Na+, K+, and Ca++ currents with properties similar to those of dark cells. In contrast, the second group of light cells had only voltage-activated outward K+ currents in response to depolarizing voltage commands. These data suggest that dark cells and light cells with inward and outward currents are capable of generating action potentials and releasing neurotransmitters onto gustatory afferent neurons in response to taste stimulation. In contrast, light cells with outward currents only likely serve a different function in the taste bud.

Animals↗
PubMed1993

Morphological types of neurons located at taste-responsive sites in the solitary nucleus of the hamster.

HRP histochemistry and microelectrode mapping were combined to study the sizes, shapes, and orientations of neuronal cell bodies and dendrites located at sites of taste-elicited single unit activity in the nucleus of the solitary tract (NST). Cells responding to sapid stimulation of the anterior tongue were extracellularly recorded using micropipettes containing HRP. Iontophoretic injection of the marker at the recording sites resulted in small (50-200 microns diameter) opaque zones bordered by a small number (2-15) of neurons with Golgi-like filling of their cell bodies, dendrites, and to some extent, their axons. The cell bodies were near (50-250 microns) the injection sites into which they sent labelled dendrites. Two broad categories of neurons were typically filled. Elongate cells had oval- to spindle-shaped cell bodies oriented mediolaterally. Two primary dendrites extended 100-300 microns from the cell body, one medially and one laterally, and branched within a cylindrical dendritic field oriented mediolaterally. A minority of the HRP-filled elongate cells had unusually long rostrally or caudally directed dendritic branches. Stellate cells had oval, round, triangular, or polygonal cell bodies and 3-5 primary dendrites coursing 200-300 microns in all directions and branching as unoriented, spheroidal fields. A minority of stellate cells had relatively unbranched wavy dendrites, resembling tentacles, while others had unusually small cell bodies (10-15 microns diameter), small dendrites, and locally arborizing axons. Of 151 labelled cells, all but 12 were remarkably confined to the rostral NST. Nearly 90% were concentrated in the rostral central cytoarchitectonic subdivision, where stellate cells predominated, or in the rostral lateral subdivision, where elongate cells predominated. These morphological types of neurons, filled at neurophysiological recording sites, are compared with cell types identified in previous light and electron microscopic studies of the cytoarchitecture, connections, and synaptic organization of the gustatory NST.

Animals↗
PubMed1990

Taste-responsive neurons and their locations in the solitary nucleus of the hamster.

The solitary nucleus (nucleus tractus solitarii), the first central relay for taste in mammals, was studied anatomically and physiologically in the golden hamster (Mesocricetus auratus). Activity of neurons to anterior tongue stimulation with sucrose, NaCl and KCl were extracellularly recorded. Electrolytic lesions or horseradish peroxidase deposits allowed subsequent localization of recording sites. Anterior tongue taste-responsive sites were restricted to a very small part of the rostral pole of the solitary nucleus, which is about 3% of the entire nucleus. Sites were confined to the rostral-central and rostral-lateral subdivisions of Whitehead, which contain a number of morphological cell types. Some chemotopic organization was seen with multi-unit recordings, with NaCl-selective sites concentrated rostrally and sucrose- and KCl-selective sites concentrated caudally. Sites with broad sensitivity were distributed throughout the gustatory region. Single neural units showing inhibition to taste stimuli, units highly reactive to all three stimuli, and units with high spontaneous rates were seen in the solitary nucleus, as well as units that responded very selectively and had low spontaneous rates. Single units with similar response profiles to sucrose, NaCl and KCl were not segregated to separate restricted locations within the taste-reactive region; their distributions overlapped. In the hamster, neurons in the anterior tongue taste region of the solitary nucleus process taste quality information in diverse ways. Highly reactive non-specific neurons, neurons that show inhibition, and neurons with high spontaneous rates are more frequently observed in the solitary nucleus than in the afferent input fibers of the chorda tympani nerve. The small region of the rostral pole enclosing taste-responsive neurons is complexly organized in relation to taste quality and contains a number of morphological cell types whose functional role in taste is not yet known.

Action Potentials↗
PubMedDate not supplied

Evidence-based practice and nursing: commentary.

With changes in health care, it has become clear that nurses need data to establish evidence for their decisions and interventions. Evidence-based practice involves the use of the best evidence available for making clinical decisions about patient care. The identification of the knowledge base for nursing practice contributes to achieving patient outcomes and making nursing practice credible.

Benchmarking↗