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Biomedical subjects

L DeSantis

Publications and source records attributed to L DeSantis.

At least 37 records · Page 2Linked to original sources
PubMed1995

Feeding and weaning practices of Cuban and Haitian immigrant mothers.

The decline of breast feeding among immigrant mothers is of concern to transcultural nurses and other health care professionals. A descriptive survey of 30 Cuban and 30 Haitian immigrant mothers in South Florida explored their feeding and weaning beliefs and practices. Findings revealed that social, economic, and political factors in their country of origin and in South Florida affected their traditional health-culture beliefs and practices related to breast and bottle feeding and weaning, initial fluid intake, introduction of supplemental foods, and administration of vitamins, minerals, and medications. Implications for transcultural nursing care are presented.

Adult↗
PubMed1994

The direct vascular relaxing action of betaxolol, carteolol and timolol in porcine long posterior ciliary artery.

The vascular relaxing properties of three beta adrenoceptor antagonists, betaxolol, carteolol and timolol, currently used in the treatment of glaucoma, were characterized, compared and contrasted in the porcine long posterior ciliary artery. Isolated arterial ring segments precontracted with increased extracellular KCl (plus 40 mM) or the thromboxane analog, U-46619 (3 x 10(-7) M), were relaxed in a concentration-dependent fashion by betaxolol, carteolol, timolol or nitroprusside. In vessel segments depolarized with increased extracellular KCl, EC50 values indicated that the intrinsic relaxant sensitivity to betaxolol was equal to that of nitroprusside, six-fold greater than that of carteolol, and ten-fold greater than that of timolol. Similarly, the maximum relaxation occurring at equimolar concentrations (10(-4) M) for the beta adrenoceptor antagonists was betaxolol > carteolol = timolol. Qualitatively similar results were noted in ring segments of the rabbit external iliac artery precontracted with increased extracellular KCl (plus 30 mM). Under conditions in which specific receptor-linked events are absent and voltage-gated Ca++ entry is maximized, the Ca++ concentration response relationship in porcine long posterior ciliary artery was shifted to the right in an apparent competitive manner by betaxolol, reflecting a 5.6-fold reduction in the sensitivity to Ca++. Conversely, nitroprusside reduced the Ca++ sensitivity three-fold in a noncompetitive fashion; not only shifting the Ca++ concentration response relationship to the right, but also depressing the maximum by 57%. Porcine long posterior ciliary arterial segments precontracted to a similar degree with U-46619, in which voltage-gated Ca++ entry is only one component of many specific cell signalling transduction mechanisms contributing to the precontraction, exhibited a sensitivity to betaxolol that was six-fold less than to nitroprusside, but two-fold greater than to timolol and 20-fold greater than to carteolol. These results are consistent with an obvious direct vascular relaxing capacity for beta adrenoceptor antagonists that primarily represents a capacity for inhibiting voltage-gated Ca++ entry in vascular smooth muscle. Additionally, the differential potencies of these three beta adrenoceptor antagonists characterized in this study suggests that this property is much more likely to contribute to any potentially beneficial effects of betaxolol than carteolol or timolol.

Animals↗
PubMed1994

Making anthropology clinically relevant to nursing care.

Transcultural nursing is generally seen as the interface between anthropology and nursing. A prime objective of transcultural nursing has been the translation of concepts from anthropology and nursing into the nursing process to guide a culturally informed clinical practice. To date, there has been a general inability of transcultural nursing to operationalize the concept of culture to develop culturally competent clinicians; that is, nurses who are capable of knowing, utilizing, and appreciating the effects of culture in the resolution of an individual, group, community, and/or family problem. A model of transcultural nursing is described, for incorporating the concept of culture into patient care. It includes the concepts of cultural brokerage, simultaneous dual ethnocentrism, multiple clinical realities, the patient as cultural informant, and cultural assessment of patient views of clinical reality. The problems of making anthropology and transcultural nursing clinically relevant through the transcultural nursing model are presented and methods are recommended for addressing such problems.

Anthropology, Cultural↗
PubMed1994

Characterization of muscarinic receptor involvement in human ciliary muscle cell function.

Muscarinic agonist-induced contraction of the ciliary muscle is generally believed to increase aqueous outflow facility and effect accommodation. We used cultured human ciliary muscle cells as a model to study the muscarinic receptor subtype(s) involved in the contractile response of the muscle. Thus, a single cell contraction assay for these muscle cells was developed. And since agonist-induced contraction of smooth muscles is expected to involve the activation of phospholipase C (PLC), we also monitored the PLC activity in these cells. Carbachol caused contraction of the muscle cells in a dose-dependent and time-dependent manner with an estimated EC50 of 1-3 microM. The contractile effect of 100 microM carbachol was antagonized by pretreatment of atropine (1 microM) and 4DAMP (10 nM, antagonist selective for the M1 and M3 receptors) but not by pirenzepine (10 microM, antagonist selective for the M1 receptor), suggesting the involvement of the M3 but not the M1 muscarinic receptor. M3 receptor is also essential for the carbachol-induced PLC activation in the ciliary muscle cells, as indicated by the activity profiles of receptor subtype selective antagonists. For example, the stimulative effect of carbachol (EC50 = 20 microM) was antagonized by pirenzepine (pKi = 6.8), HHSiD (pKi = 7.6), 4DAMP (pKi = 9.5) and methoctramine (pKi < 6). Thus, these results indicate that an M3-like receptor subtype is essential in mediating the muscarinic agonists-induced functional changes, such as PLC activation or muscle contraction, in the ciliary muscle.

Atropine↗
PubMed1994

Things that help and hinder adolescent sibling bereavement.

A taxonomy of the things that help and hinder adolescents' sibling bereavement was developed from the responses of 140 bereaved adolescents to the questions What helped you cope with your sibling's death? and What made it harder to cope with your sibling's death? The dichotomous taxonomic framework revealed five categories. The categories of self, family, friends, social system, and time contained descriptions of things that helped coping. The categories of self, family, and social system also included descriptions of things that hindered coping with sibling grief. Support considered helpful was perceived as "people being there for me." Support that was considered as not helpful (insensitive) was perceived as "people not being there for me." Two themes emerged from the data. The theme of resourcefulness pervaded each of the helped categories and served to increase the adolescents' sense of resiliency. The theme of helplessness pervaded the three hindered categories and created a sense of vulnerability.

Adaptation, Psychological↗
PubMed1994

Preliminary characterization of a transformed cell strain derived from human trabecular meshwork.

Cells isolated from the trabecular meshwork (TM) of a male glaucoma patient were transformed by transfection with an origin defective mutant of SV40 virus. Transformation dramatically increased the growth rate of these cells (designated HTM-3 cells), allowing biochemical and pharmacological characterization. The HTM-3 cells had cytoskeletal components that were reported to be present in TM tissue and non-transformed TM cells. Vimentin, tubulin and smooth muscle specific alpha-actin, but not desmin, were localized in these cells by immunocytochemistry. The extracellular matrix components collagen types I, III and IV, fibronectin and laminin were found in HTM-3 cells as well as their non-transformed parental cells. As predicted, the protein profile of the HTM-3 cells revealed by two-dimensional gel electrophoresis was different from that of the non-transformed cells, probably due to the enhanced growth characteristics of these cells. Furthermore, HTM-3 cells had various intracellular second messenger systems that responded to pharmacological agents. Forskolin, prostaglandin E2, beta-adrenergic and adenosine A2 agonists stimulated the adenylyl cyclase in these cells, whereas muscarinic, serotonergic, dopaminergic and other agonists were ineffective. Sodium nitroprusside increased the intracellular concentration of cGMP, demonstrating the presence of a functional guanylyl cyclase. Phospholipase C activity in these cells was also detected. Muscarinic agonists, histamine and bradykinin, but not adrenergic, serotonergic agonists or prostaglandins, increased phosphoinositide turnover. These drug responses of HTM-3 cells agree with published data on primary TM cells and TM tissues, suggesting that the transformed cells may be a valid substitute for certain pharmacological studies of TM.

Aged↗
PubMed1994

Childhood independence: views of Cuban and Haitian immigrant mothers.

Failure of nurses and other health care providers to recognize the influence of culture on child development may lead to inappropriate expectations and mislabeling of children as developmentally slow. The effect of cultural influences on parental expectations of children was evident in a study of child-rearing beliefs of 30 Cuban and 30 Haitian immigrant mothers in South Florida. Both Cuban and Haitian children would be considered lagging developmentally when compared with measurements on the personal-social dimension of the Denver II and expectations of American society. Culture-specific implications for transcultural nursing care based on the concept of culture brokerage are discussed.

Adult↗
PubMed1994

Muscarinic effects on cellular functions in cultured human ciliary muscle cells.

PURPOSE: To characterize the pharmacology of the carbachol-induced changes of phospholipase C (PLC) activity and intracellular calcium concentration ([Ca2+]i) in cultured human ciliary muscle cells. METHODS: Changes in PLC activity of cultured human ciliary muscle cells were determined by production of inositol phosphates. Single-cell dynamic fluorescence ratio imaging was used to determine [Ca2+]i. RESULTS: Carbachol, oxotremorine-M, aceclidine, and pilocarpine stimulated PLC with mean EC50s of 20, 8, 17, and 2 microM, respectively. The effect of carbachol on PLC was partially suppressed by extracellular Ca2+ depletion. This muscarinic effect was blocked by muscarinic antagonists, such as atropine (apparent pKi = 9.12, nonselective for muscarinic receptor subtypes), pirenzepine (pKi = 6.76, selective for the M1 receptor subtype), 4DAMP (pKi = 9.25, selective for the M1 and M3 subtypes), and fHHSiD (pKi = 7.77, selective for the M3 subtype). In [Ca2+]i experiments, carbachol increased [Ca2+]i transients in human ciliary muscle cells in a dose-dependent manner with a mean EC50 of 7 microM. 4DAMP was approximately 100 times more potent than pirenzepine in the inhibition of the carbachol-induced [Ca2+]i increase. [Ca2+]i oscillations were observed after carbachol stimulation and persisted after extracellular Ca2+ depletion. CONCLUSIONS: Muscarinic agonists activate PLC and increase [Ca2+]i in cultured human ciliary muscle cells through an M3-like muscarinic receptor subtype.

Calcium↗
PubMed1993

Characterization of soluble guanylyl cyclase in transformed human non-pigmented epithelial cells.

Topical application of nitro vasodilators, such as sodium nitroprusside, reduces intraocular pressure. In brain and blood vessels, nitro vasodilators activate soluble guanylyl cyclases, producing cGMP. The location and molecular identity of ocular guanylyl cyclases are unknown. We studied transformed human non-pigmented ciliary epithelial cells, whose parental cells are responsible for the production of aqueous humor. Sodium nitroprusside increased cGMP 40 to 60 fold in a time and concentration dependent manner (EC50 40 to 100 microM). Methylene blue inhibited this effect (IC50 0.6 microM in the presence of 100 microM sodium nitroprusside). We also detected mRNA for the alpha 1 and beta 1, but not the beta 2, subunit isoforms of soluble guanylyl cyclase in these cells by Northern blotting. We conclude that transformed non-pigmented epithelial cells contain an active heterodimeric soluble guanylyl cyclase composed of at least alpha 1 and beta 1 subunits.

Blotting, Northern↗
PubMed1993

Colour vision anomalies following experimental glaucoma in monkeys.

Spectral sensitivity defects, associated with chronic elevated intraocular pressure (IOP) produced by Argon laser trabeculoplasty, were studied in monkeys. Increment-threshold spectral sensitivity (ITSS) and threshold versus intensity (TVI) functions were measured using a behavioural model. Elevated IOP resulted in short wavelength (SW) sensitivity losses characteristic of many ocular diseases. The amount of SW sensitivity loss for ITSS functions depended upon the intensity level and chromatic composition of the background field. The optimum condition identifying the greatest SW sensitivity reduction was a yellow background of moderate intensity (100-1000 Td). In the early stages of experimental glaucoma, the cone mechanisms and the rod mechanism typically showed decreased test and field sensitivities. The SW cone pathway has slightly greater threshold elevation (approximately 0.3 log unit) compared to the rod and cone pathways. On the other hand, in the advanced stages of experimental glaucoma, the largest sensitivity losses were in the longer-wavelength, red-green opponent mechanisms, with the rod and SW cone pathways showing smaller losses. The similarities of the colour vision anomalies in this animal model with those of patients with glaucoma, provides support for its use as an experimental model for human glaucoma.

Animals↗
PubMed1993

Mechanisms mediating visual detection in static perimetry.

PURPOSE: The usual stimuli in static perimetry are white-light luminance increments. However, the specific visual detection mechanisms involved in perimetry are unknown because all classes of neural mechanisms are sensitive to spectrally broadband stimuli. The objective of this study was to determine the relative sensitivities of nonopponent and opponent detecting mechanisms under standard perimetry test conditions. METHODS: Using trained rhesus monkey subjects, the relative sensitivities of the vision mechanisms for the detection of perimetry test stimuli were determined through psychophysical measurements of spectral sensitivity at each of the test field locations of the C24-2 threshold program on the Humphrey Field Analyzer (Allergan Humphrey, San Leandro, CA). The spectral sensitivity functions were analyzed by a three-channel model that incorporated independent short-wavelength-sensitive, nonopponent (luminance), and opponent (chromatic) spectral sensitivity mechanisms. RESULTS: The visual detection mechanisms for perimetry thresholds varied as a function of the size and wavelength of the test field. With the perimeter's standard stimulus (Goldmann Size III) and bowl illumination (31.5 asb), the presence of a short-wavelength-sensitive mechanism was clearly evident at all field locations, but its relative sensitivity systematically declined with eccentricity. Under these conditions, the sensitivities of the opponent and nonopponent mechanisms were approximately equal at most field locations. With a larger stimulus (Goldmann Size V), however, the contribution of the opponent spectral sensitivity mechanism was more apparent over most of the central field and the alterations of sensitivity with eccentricity were less pronounced. In contrast, a small test field (Goldmann Size II) appeared to bias detection toward nonopponent mechanisms. CONCLUSION: The results of these investigations indicate that detection thresholds during perimetry can be effectively biased toward different photopic, visual processing channels through the appropriate selection of size and wavelength of the test stimulus.

Animals↗
PubMed1993

Behavioral perimetry in monkeys.

PURPOSE: Normative data on the systematic changes in visual sensitivity as a function of retinal eccentricity have provided the basis for efficient threshold strategies and data analysis routines for static perimetry. The standard methods of assessing visual field changes in patients also could be used for monkeys with experimentally induced ocular disorders if the normal visual fields of monkeys and humans were similar. METHODS: Normal visual field data from three rhesus monkeys were compared to data from eight human subjects using the standard threshold programs of the Humphrey Field Analyzer. RESULTS: The experimental paradigm developed for these measurements provided excellent behavioral control for the monkeys, with reliability indices well within acceptable limits. The visual field data from monkeys were comparable to those from humans with respect to: (1) sensitivity as a function of stimulus field size; (2) the derived Statpac global indices; and (3) the variance of threshold measurements across the visual field. CONCLUSION: The visual fields of monkeys and humans are similar, and the techniques of computerized perimetry may be applied to monkey subjects without significant modification.

Adult↗
PubMed1993

Single-cell contraction assay for human ciliary muscle cells. Effect of carbachol.

PURPOSE: The authors developed an assay to observe the contraction of a single human ciliary muscle cell. METHODS: Cultured human ciliary muscle cells were partially detached from the culture dish by incubation with a nonenzymatic dissociation buffer and treated with carbachol or pilocarpine. Contraction was quantified by measuring the cross-sectional surface areas of the cells. RESULTS: Carbachol decreased the cell surface area in a time-dependent manner. Contraction was observed within 1 min after the addition of carbachol and completed in less than 15 min. The effect of carbachol was dose dependent. For example, at 10 min after treatment with 10 mumol/l carbachol, the relative surface areas of cells decreased to 47% +/- 4% (mean +/- standard error of the mean, n = 7, with surface area at 0 min defined as 100%). The relative surface areas were 74% +/- 4% (n = 7) after 1 mumol/l and 100% +/- 9% (n = 7) after 0.1 mumol/l carbachol treatment. This contractile effect was antagonized by pretreatment with atropine, a specific muscarinic antagonist. CONCLUSIONS: A simple method was established to study the functional changes of human ciliary muscle cells.

Biological Assay↗
PubMed1992

Health education and the immigrant Haitian mother: cultural insights for community health nurses.

Lack of information about health education from the perspective of immigrants was the basis of a descriptive survey of 30 Haitian mothers in southeast Florida. Subjects were interviewed regarding the value of health education received while seeking preventive health care for infants and preschool children in community health settings, their access to other sources of health education, and their perceptions of what community health care providers could do to assist them in improving child health. Ninety-seven percent took children for well-child care to medical facilities, and 66% received health education during the visits. Seventy percent had access to health-education programs through clinics or the media. Impediments to effective health education were lack of providers who speak Haitian Creole, need for more nurses, and long clinic waiting periods. Nurses were considered the best persons to do health teaching; radio and clinic lectures were the preferred media. Teaching was valuable if it was understandable and practical, reinforced parenting abilities, and allowed time for questions. Results are related to socioeconomic and political factors, traditional Haitian health culture, and cultural views of the cognitive development in children. Culture-specific strategies related to the modes and foci of health education are discussed.

Community Health Nursing↗
PubMed1991

Development of substantive theory in nursing.

The lack of a comprehensive, substantive theory base has resulted in the profession of nursing borrowing theoretical assumptions, concepts, and research instruments from other disciplines to examine nursing phenomena. Nurse researchers have focused their attention primarily on applied research leaving the development of substantive theory to others. If the nursing profession is to develop a scientifically-based practice, nurses will need to engage in debates about the need for and methods of generating substantive theory and shift from the use of borrowed knowledge and methods to original nursing research. In order to broaden the theoretical conceptualisations and directions of nursing research for the development of a substantive theory base, multi-method perspectives are necessary. Triangulation of qualitative and quantitative methods is one way to design research that will allow for development of substantive theory through the use of multiple methodology. This paper describes one method of preparing doctoral nurse students for triangulation of methods and to develop substantive theory for nursing practice.

Humans↗
PubMed1990

The immigrant Haitian mother: transcultural nursing perspective on preventive health care for children.

Thirty immigrant Haitian mothers in Southeast Florida were interviewed regarding their beliefs and practices about preventive health care (illness prevention and health maintenance measures) for infants and preschool children (up to age 5). All mothers used preventive health care measures from both the Western biomedical and traditional Haitian ethnomedical (folk) systems. Ninety-seven percent used magico-religious measures; 47% administered home remedies; 47% gave children over-the-counter drugs; and 35% utilized a variety of measures to ensure cold air did not enter neonates and cause illness or pain. The Haitian mothers considered the preventive health care measures effective because the children remained healthy and will likely use them again. They sought consultation from a variety of individuals who formed their health management groups and child caretaker networks. Infants and toddlers were considered at higher risk than newborns for illness due to "evil harm" inflicted by other people and/or voodoo spirits. Implications for transcultural nursing practice include developing community outreach programs, implementing nursing interventions that combine biomedical and ethnomedical preventive health care measures, and functioning as part of the health management group. The authors wish to thank Maude Vincent, R.N., for her assistance in data gathering and analysis.

Adult↗