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Biomedical subjects

M A Hart

Publications and source records attributed to M A Hart.

At least 19 recordsLinked to original sources
PubMed2000

Manipulations of sensory information: a test of the hypothesis of redundancy of knowledge of results.

The hypothesis of redundancy in knowledge of results was examined by manipulating the amount and location of sensory information available to participants performing a coincident anticipation timing task. Either the last 8 lights or the last 16 lights of the visual display were visible to 48 participants. Following an acquisition phase, learning was tested over immediate (5-min.) and delayed (24-hr.) retention intervals. The main finding was that performance was better when knowledge of results was present, regardless of the amount of sensory information available; therefore, knowledge of results was not redundant information for learning this task.

Adult↗
PubMed1999

Ocular anterior chamber dysgenesis in craniosynostosis syndromes with a fibroblast growth factor receptor 2 mutation.

Fibroblast growth factor receptor (FGFR) mutations have been found in craniosynostosis syndromes with and without limb and/or dermatologic anomalies. Ocular manifestations of FGFR2 syndromes are reported to include shallow orbits, proptosis, strabismus, and hypertelorism, but no ocular anterior chamber, structural abnormalities have been reported until now. We evaluated three unrelated patients with severe Crouzon or Pfeiffer syndrome. Two of them had ocular findings consistent with Peters anomaly, and the third patient had opaque corneae, thickened irides and ciliary bodies, and shallow anterior chambers with occluded angles. Craniosynostosis with and without cloverleaf skull deformity, large anterior fontanelle, hydrocephalus, proptosis, depressed nasal bridge, choanal stenosis/ atresia, midface hypoplasia, and elbow contractures were also present. These patients had airway compromise, seizures, and two died by age 15 months. All three cases were found to have the same FGFR2 Ser351Cys (1231C to G) mutation predicted to form an aberrant disulfide bond(s) and affect ligand binding. Seven patients with isolated Peters anomaly, two patients with Peters plus syndrome, and three cases with typical Antley-Bixler syndrome were screened for this mutation, but none was found. These phenotype/genotype data demonstrate that FGFR2 is involved in the development of the anterior chamber of the eye and that the Ser351Cys mutation is associated with a severe phenotype and clinical course.

Acrocephalosyndactylia↗
PubMed1998

Back to class.

Pregnancy is typically viewed as a normal, joyous time for families. Most expectant parents have reasonable assumptions that the pregnancy will progress smoothly from conception through birth and the eventual homecoming with the newborn (Snyder, 1979). However, for high-risk antepartum patients and their families, that Norman Rockwell-like scenario may be interrupted by long hospital stays, confinements to bed rest, and complications before the baby's birth. Providing care for these families offers both a challenge and an opportunity for perinatal nurses.

Adaptation, Psychological↗
PubMed1998

Self-care agency in two groups of pregnant women.

Self-care agency, a multidimensional concept in Orem's self-care deficit nursing theory, includes motivation, decision-making, energy, and knowledge necessary to perform self-care actions. Basic conditioning factors affect individuals' development and exercise of self-care agency. Secondary analysis of Appraisal of Self-Care Agency (ASA) scores in two groups of pregnant women, (1) a childbirth education group (n = 119) and (2) a clinic group (n = 127) was completed. Group 2 had significantly higher ASA scores. Several basic conditioning factors influenced ASA scores. Results offer implications for Orem's theory and maternity nursing practice.

Adult↗
PubMed1997

Couples' attitudes toward childbirth participation: relationship to evaluation of labor and delivery.

The article reports a correlational, partial replication study investigating the relationship between couples' prenatal attitudes toward childbirth participation and perceptions of their labor and delivery experiences. The Prenatal Attitude toward Childbirth Participation Scale was administered to 119 couples before and after attendance at a childbirth education course. The Labor Delivery Evaluation Scale, the Labor Agency Scale, and the Delivery Agency Scale were administered after delivery. Results showed that childbirth education affected couples' anticipated levels of control during labor and delivery. Anticipated and perceived levels of control were associated, and perceived levels of control correlated with overall evaluations of childbirth experiences. These findings suggest that childbirth educators and health care providers should focus on participants' opportunities to exercise control during childbirth and on identifying emergency situations during which control must be relinquished to the health care team.

Adolescent↗
PubMed1997

A preliminary comparison of stimulus presentation methods with the Bassin Anticipation Timing Task.

The Bassin Anticipation Timing Task was used to compare response performance when the stimulus terminated at the target location to when the stimulus continued past the target location. Two conditions (terminating and continuing) were tested by measuring timing errors on the task. Analyses indicated no significant differences in absolute error and variable error between the conditions. However, analysis of constant error showed a significant effect, with the timing errors being fewer on the terminating condition. These results suggest that the two stimulus presentation methods with the Bassin Anticipation Task differentially influence timing performance.

Discrimination, Psychological↗
PubMed1995

Orem's self-care deficit theory: research with pregnant women.

A causal model of relationships among self-care agency, basic prenatal care actions, foundations for dependent-care agency, and selected pregnancy outcomes was investigated. This cross-sectional correlation study was conducted on a random sample of 127 women at least 30 weeks pregnant. Path analysis was used to analyze the data. Self-care agency was significantly and directly related to basic prenatal care actions and foundations for dependent-care agency, which in turn were directly related to infant birth weight. Findings lend support to Orem's theory and offer implications for maternity nursing practice and research.

Adult↗
PubMed1989

Role of C1q in phagocytosis of Salmonella minnesota by pulmonary endothelial cells.

The Re mutant of Salmonella minnesota adheres in much greater numbers than the wild type to endothelial cells derived from the bovine pulmonary artery. Since the Re mutant is distinguished from wild-type S. minnesota by its ability to bind C1q and since endothelial cells possess receptors for C1q, we examined the role of C1q in the phagocytosis of the S. minnesota Re mutant. First, preincubating endothelial cells with C1q-enriched medium resulted in increased adherence of the Re mutant (17.9 x 10(4) versus 6.6 x 10(4]. Second, preincubating the Re mutant with C1q-enriched medium resulted in increased numbers of adherent bacteria (62.1 x 10(4) versus 6.6 x 10(4]. Preincubation of both endothelial cells and bacteria with C1q-enriched medium resulted in increased adherence above control levels but less adherence than when either cells or bacteria were preincubated separately in C1q-enriched medium. If serum depleted of C1q was used for preincubation of endothelial cells or bacteria, adherence was reduced below control levels. Thus, C1q plays an important role in the initial steps (recognition, binding, and ingestion) of phagocytosis. Next, the role of C1q was investigated in the respiratory burst response. Levels of superoxide anion released from endothelial cells 15 min after phagocytosis of the Re mutant (100 bacteria per endothelial cell) were assayed by measurement of the superoxide dismutase-inhibitable reduction of ferricytochrome c. Superoxide anion release was increased during phagocytosis of the Re mutant (35 nmol of O2- per 3 x 10(6) endothelial cells) and was also elevated above control values by incubation with soluble C1q (10 nmol of O2- per 3 x 10(6) endothelial cells). These results indicate a role for C1q in both the ingestion and the response of endothelial cells to the S. minnesota Re mutant.

Animals↗
PubMed1986

Aggregate anaphylaxis and carboxypeptidase N.

Bradykinin (BK) is widely believed to play a role in the pathogenesis of anaphylaxis. To help clarify any such roles, we examined for effects of inhibitors of kininase II (angiotensin converting enzyme, ACE) and "kininase I" (carboxypeptidase N, CPN), on the early course of egg albumin-induced aggregate anaphylaxis in anesthetized guinea pigs. In this model, pulmonary and systemic arterial blood pressure (BP) rise (unless pulmonary fibrillation occurs), lung wgt increases by approximately 60% and pulmonary microvessels are occluded by cell-rich thrombi, all within 5 min of i.v. antigen. The 30 min mortality rate is approximately 2%. ACE inhibitors (BPP9a, Captopril and MK 422; doses up to 140 mumol/kg) do not make anaphylaxis more nor less severe in terms discernible by changes in BP, lung wgt, EKG or intravascular coagulation. In marked contrast, an inhibitor of CPN (2-mercaptomethyl-3-guanidinoethylthiopropionic acid, 2-MGP; 8-16 mumol/kg) increases the 30 min mortality rate to 94% and lung wgt to 180% of control. The animals die in ventricular fibrillation. Given the enormous BK potentiating effects of BPP9a, Captopril and MK 422, it seems likely that little if any BK is formed in the early min of anaphylaxis. 2-MGP does not potentiate BP effects of BK but markedly potentiates effects of C3a anaphylatoxin. Thus, our data support the views that BK is neither a primary nor secondary mediator of aggregate anaphylaxis, and the adverse effects of 2-MGP are best explained in terms of preservation of anaphylatoxins and not in terms of preservation of kinins.

3-Mercaptopropionic Acid↗
PubMed1979

Isolation and culture of endothelial cells from the lungs of small animals.

Techniques are descirbed for the isolation and culture of endothelial cells from the lungs of small animals. The cells are collected by retrograde perfusion of blood-free lungs with buffered saline containing collagenase. The cells are characterized by light microscopy, electron microscopy of thin sections and surface replicas, and by the presence of angiotensin-converting enzyme (ACE). ACE was assayed using 3H-benzoyl-Phe-Ala-Pro as substrate and was localized by indirect immunofluorescence using guinea pig endothelial cells incubated with rabbit antibodies to guinea pig lung ACE followed by goat anti-rabbit globulins conjugated to fluorescein. Thus, endothelial cultures can be established using small animals commonly employed in studies of pulmonary processing of vasoactive substances.

Animals↗
PubMed1978

Surface replicas of pulmonary endothelial cells in culture.

Pulmonary endothelial cells possess a variety of enzymes on their surface. However, the topographical distribution of these enzymes is not known. In this report we describe a simple technique for the preparation of surface replicas of pulmonary endothelial cells using an unmodified critical point drying apparatus and a high vacuum freeze-etch unit. The technique should be applicable for use with all cells in monolayer culture. Endothelial cells grown on glass slides or coverslips were washed thoroughly, fixed and dehydrated. The monolayers were then critical point dried. Surface replicas were prepared in a Balzer's freeze-etch unit. The advantages of surface replicas are that they can be examined with the resolving power of the transmission electron microscope and can be used to examine whole cells. The potential for the surface replica technique may lie in mapping specific enzymes, receptors and cell surface factors. Therefore, to provide a basis for such studies, we have described the appearance of pulmonary endothelial cells in surface replicas.

Cell Division↗
PubMed1975

The distribution of orthogonal assemblies and other intercalated particles in frog sartorius and rabbit sacrospinalis muscle.

Freeze-fracture replicas have been prepared from two fast-acting vertebrate muscles (frog sartorius and rabbit sacrospinalis) and are described with particular reference to the distribution of intercalated particles in the plasma membrane. T-tubule and SR cisternae. Orthogonal assemblies of small particles are present on the A face plasma membrane in each instance, and their distribution (in sartorius) is found to be random with respect to the underlying myofibrillar sarcomere repeat. Such assemblies are not present on A or B faces of T-tubule or SR cisternae. Asymmetric particle distribution is described for fracture faces of the T-tubules and SR: the profuse particle packing of the SR A face is uniform from terminal cisternae to medial fenestrated collar. Intercalated particles are present on A and B faces of T-tubule fractures; more commonly on the latter. These results are compared with studies on insect muscles, and a comparative approach to further studies on the correlation between membrane structure and function is discussed.

Animals↗