In vitro cytotoxicity of a remineralizing resin-based calcium phosphate cement.

Recently, a resin-based calcium phosphate cement (RCPC) has been reported as a remineralizing pulp-capping or lining cement. RCPC consists mainly of tetracalcium and dicalcium phosphates, ethoxylated bisphenol A dimethacrylate and pyromellitic glycerol dimethacrylate monomers and photo- and chemical initiators. OBJECTIVES: Here, the cytotoxic effects of RCPC were evaluated. The hypothesis was that RCPC induced only minor cytotoxic response in immortalized murine odontoblast and pulp cells, comparable to that produced by similar dimethacrylates due to unpolymerized dimethacrylate monomer present after curing. METHODS: Cytotoxicity was determined following the changes in cell succinate dehydrogenase activity after 24 h exposure to the cement components and after a 24 h recovery period. A fourfold range of concentrations was tested of the monomers, the eluate of cured RCPC leached in Dulbecco's modified Eagle's medium, and crushed cured cement in dimethyl sulfoxide. RESULTS: The monomers themselves had cytotoxicities similar to those reported for other dimethacrylates, although they are significantly less toxic than Bis-GMA. Differential cell sensitivity was demonstrated, with the pulp cells having greater sensitivity to the unpolymerized monomer than the odontoblast-like cells. The leached components have cytotoxicity similar to that of the free monomers. The crushed material demonstrated no apparent cytotoxicity at the dilutions tested. SIGNIFICANCE: These data demonstrate that RCPC has an in vitro cytotoxicity that is comparable to other materials containing dimethacrylate monomers and suggest that the material may be suitable for use in dental restorations. The data also indicate that the pulp cells appear more sensitive to dimethacrylates than the odontoblasts.     

Update on chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease is one of the most significant chronic illnesses of adults. Comprehensive care of the affected patient requires the medical-surgical nurse to have knowledge of the disease process, collaborative management, and nursing care based on research and current practice guidelines.     

Correlation between 5-HT7 receptor affinity and protection against sound-induced seizures in DBA/2J mice

Audiogenic seizures can be induced in DBA/2J mice following intense auditory stimulation. A number of neurotransmitters, including 5-hydroxytryptamine (5-HT), are believed to be involved in mediating this effect since it has been shown previously that depletion of 5-HT or blockade of 5-HT receptors protects DBA/2J mice from these audiogenic seizures. The present study was undertaken to determine whether antagonism of the newly identified 5-HT₇ receptor may protect DBA/2J mice from audiogenic seizures by attempting to correlate in vivo potency of compounds with their affinity at the 5-HT₇ receptor. All compounds used in the correlation were shown to be antagonists at the 5-HT₇ receptor and a statistically significant correlation was observed between 5-HT₇ affinity and doses for half-maximal response (ED₅₀) for protection of DBA/2J mice from sound-induced seizures (r = 0.80; P < 0.05). No significant correlation was observed between in vivo activity and affinity at either 5-HT_1A, 5-HT_2A or 5-HT_2C receptors. It is also unlikely that interactions between the 5-ht₅ receptor will protect DBA/2J mice from audiogenic seizures since metergoline and mesulergine which are both active in this in vivo model have no affinity for the 5-ht₅ receptor. There are similarities between the pharmacology of the 5-HT₇ receptor and that of the 5-HT_1A receptor, however the correlation between the in vivo potency in DBA/2J mice and 5-HT_1A affinity was not significant. Furthermore, the 5-HT_1A receptor antagonist WAY 100135 did not protect DBA/2J mice from audiogenic seizures at doses that antagonise 5-HT_1A receptor-mediated effects in mice. These data suggest that antagonism of 5-HT₇ receptors may protect against audiogenic seizures in DBA/2J mice although a definitive conclusion must await studies with selective 5-HT₇ antagonists. Received: 20 March 1997 / Accepted: 10 August 1997     

Risk Factors for a First Febrile Seizure: A Matched Case-Control Study

Summary We conducted a matched casecontrol study to identify risk factors for first febrile seizures, with special emphasis on characteristics of the acute illness episode. Cases were identified through hospital emergency departments; controls were identified through outpatient clinics and emergency departments. Sixtynine children with first febrile seizures and no history of previous unprovoked seizures were matched for age (±6 months), site of routine pediatric care, and date of visit (±weeks) with 1 or 2 febrile controls who had no history of previous febrile or unprovoked seizures. Medical records for the index visit were reviewed, and parents were interviewed by telephone. Illness characteristics examined included height of temperature, type of underlying illness, contact with a physician during the illness but before the index visit, and use of acetaminophen or decongestants. Family history of febrile and of unprovoked seizures, sociodemographic characteristics, daycare use, and selected preand perinatal variables were also studied. On multivariable analysis, significant independent risk factors were height of temperature, history of febrile seizures in a firstor in a higher degree relative. Gastroenteritis as the underlying illness had a significant inverse (i.e., protective) association with febrile seizures. Maternal smoking during pregnancy was a marginally significant predictor of febrile seizures.     

Anthropology, nursing and midwifery: a natural alliance?

Anthropology, and its supposed operationalisation within transcultural nursing, is becoming increasingly prominent in educational curricula in the U.K. This increase in interest is driven both by governmental pressure to provide more culturally appropriate care, and an intuitive notion that anthropology, nursing and other related professions such as midwifery have a common basis of mutually overlapping and re-enforcing theory and practice. This paper explores the question of whether there is a natural alliance between anthropology, and the applied aspects of health care disciplines such as nursing and midwifery, by examining some of the concepts underlying each discipline, and the ways in which these concepts are applied in practice. Anthropology is the study of culture, and it is suggested that a more complete understanding of this central concept is essential if it is to be utilised in the applied disciplines encompassed by the practice of nursing and midwifery.     

The poor pay more: Health-related inequality in Thailand

This paper examines the equality of utilization for equal need and equity of out-of-pocket expenditure for health services in a large urban area in Thailand. Data from a household health interview survey were used to explore patterns of perceived morbidity, utilization of various treatment sources, and out-of-pocket payment. Financial access to health care, as reflected in medical benefit/insurance cover, appeared to influence reported illness and hospitalization rates. Gross lack of access to health care amongst lower socio-economic groups was not the main problem in this densely populated urban area because people could choose and use alternative health services according to their ability and willingness to pay. The corollary, however, was an inequitable pattern of out-of-pocket health expenditure by income quintile and per capita. The underprivileged were more likely to pay out of their own pocket for their health problems, and to pay out of proportion to their household income when compared with more privileged groups. Furthermore, the underprivileged were least likely to be covered by government health benefit schemes, in contrast in particular to civil servants, who paid less out of pocket and did not contribute to their medical benefit fund. The private health sector (private clinics and private hospitals) was the major provider of health care to urban dwellers for both outpatient and inpatient services. Policy options for the short and long term to improve the equity of payment systems for health care are discussed.     

Crystallization of a copolyester in microlayers and blends with polycarbonate

The crystallization behavior of coextruded microlayered sheets comprised of 657 alternating layers of polycarbonate (PC) and a miscible copolyester of mainly 1,4-cyclohexanedimethanol and terephthalic acid (KODAR) was investigated as a function of annealing time when the KODAR was crystallized isothermally from the glass at 195°C. Comparisons were made with crystallization of KODAR alone, and with crystallization of KODAR from melt blends with PC. The kinetics of crystallization and the morphology of the crystallized KODAR were characterized with differential scanning calorimetry, and by examination of thin sections microtomed from annealed specimens in the polarized light microscope and the transmission electron microscope. The growth rate of small, birefringent KODAR spherulites was non-linear, and was strongly affected by diffusion of PC into the KODAR layers. Diffusion of amorphous PC into the KODAR layers retarded nucleation and spherulite growth and decreased spherulite density. The effect became more pronounced as the KODAR layer thickness was reduced. Spherulities nucleated randomly throughout the KODAR layers in the PC/KODAR 20/80 (w/w) microlayer and grew rapidly to form a continuous layer of impinged spherulites. In contrast, spherulites in the PC/KODAR 40/60 and 60/40 microlayers nucleated and grew along the center of the KODAR layers where the KODAR concentration was highest.     

The Effect of High-Dose Ascorbate Supplementation on Plasma Lipoprotein(a) Levels in Patients With Premature Coronary Heart Disease

Study Objective . To determine the efficacy of high-dose ascorbate supplementation in lowering lipoprotein(a) [Lp(a)] levels in patients with premature coronary heart disease (CHD). Design . Randomized, double-blind, placebo-controlled trial. Setting . Outpatient clinic. Patients . Forty-four patients with documented premature CHD. defined as confirmed myocardial infarction and/or angiographically determined stenosis of 50% or greater in at least one major coronary artery before age 60 years. Interventions . Patients were block randomized on the basis of age, gender, and screening Lp(a) concentrations to receive ascorbate 4.5 g/day or placebo for 12 weeks. Measurements and Main Results . High-dose ascorbate was well tolerated and produced a marked elevation in mean plasma ascorbate levels (+1.2 mg/dl; p<0.001). Multiple linear regression analysis revealed no significant effect of supplementation on postintervention Lp(a) levels (p=0.39) in a model that included treatment group assignment, and baseline Lp(a) levels. Conclusions . Our findings do not support a clinically important lowering effect of high-dose ascorbate on plasma Lp(a) in patients with premature CHD.