Care of chronically ill children in schools.
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Child↗
Biomedical subjects
D K Walker
Publications and source records attributed to D K Walker.
New generation tissue valves. Their in vitro function in the mitral position.
The in vitro function of six tissue valves from four manufacturers has been assessed. One porcine bioprosthesis (Carpentier-Edwards supra-annular) and five pericardial valves (Edwards, Hancock, Ionescu-Shiley, Ionescu-Shiley low-profile, and Mitral Medical Mitroflow) were tested. Valve function was measured in a pulse duplicator simulating conditions of sinus rhythm (60, 80, and 120 beats/min and stroke volume 70 ml) and supraventricular tachycardia (200 beats/min and stroke volume 30 ml). Under each of these test conditions, mean transvalvular pressure, regurgitation, and transvalvular energy loss were determined and used to compare valve function. The porcine valve showed the largest mean transvalvular pressure during forward flow. The total energy loss of this valve, however, was not the largest for the valves tested. The total transvalvular energy loss ranged between 3% and 12% for all valves and conditions. For all valves, energy loss and regurgitation were greatest during simulated tachycardia.
Bioprosthesis↗
Development and in vitro assessment of a new two-leaflet replacement heart valve designed using computer-generated bubble surfaces.
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Computers↗
The Björk-Shiley and Ionescu-Shiley heart valve prostheses. In vitro comparison of their hydrodynamic performance in the mitral position.
Shiley Scientific Inc., are now manufacturing six types of prosthetic heart valves. There are four different models of the Björk-Shiley and two versions of the Ionescu-Shiley pericardial heart valve. The Björk-Shiley valves are those with a spherical disc, 60 degrees and 70 degrees opening convexo-concave discs, and the latest monostrut model. The Ionescu-Shiley valves are the original titanium stent model and the latest Delrin stent low profile model. The hydrodynamic performance of these valves in the mitral position all having a tissue annulus diameter of 29 mm, has been measured. Tests were performed in a pulse duplicator simulating sinus rhythm at heart rates of 60, 80 and 120 beats per minute (BPM) with a stroke volume (SV) between 69 and 73 ml and at a heart rate of 200 BPM with SV between 27 and 34 ml. The latter test condition simulates a situation of supraventricular tachycardia. Mean transmitral pressure, regurgitation, and transmitral energy loss for each valve under each set of conditions were compared. All the Björk-Shiley valves were tested in two orientations with the major flow orifice oriented either anteriorly (A) or posteriorly (P). For all valves, it was found that the major contribution to the total transmitral energy loss, most apparent at 200 BPM, was caused by regurgitation and that at 60, 80 and 200 BPM, the forward flow phase contributed only a small amount to the total energy loss. The small intentional leakage across the Björk-Shiley valves is minor compared to closing regurgitation but is a major contributor to transmitral energy loss.(ABSTRACT TRUNCATED AT 250 WORDS)
Cardiac Output↗
Comparisons between inner-city and private school adolescents' perceptions of health problems.
A youth health survey was administered to 247 students in an inner-city ghetto high school and 404 students in a private boarding school. Significant differences between the two socioeconomic groups were found for responses about health information, health concerns and problems, and health status and service utilization. Sex-related issues were of greater concern to the private school youth and they desired more help with depression-sadness and birth control. Inner-city youth had more health worries and indicated a desire for more help with physical problems such as toothaches, headaches, and stomach aches, and social problems such as racial discrimination and parent relations. From a list of 22 health problems, the inner-city youth ranked dental problems, acne, and health worries highest while the private school youth ranked depression-sadness, tiredness, and acne highest. Regardless of social class, most adolescents perceived large gaps in their health education. One implication of our data is that the specific self-reported needs and concerns of adolescents should be considered in planning health services and education programs.
Adolescent↗
Parental smoking and the risk of childhood asthma.
Data from two random population surveys are used to assess the relationship between parental smoking and the prevalence of asthma in children aged 0-17. Data from a 1977 Midwestern urbanized county indicate that, if mothers smoked, the prevalence of parent reported asthma increased from 5.0 per cent to 7.7 per cent (estimated relative risk of 1.5), and the prevalence of functionally impairing asthma increased from 1.1 per cent to 2.2 per cent (relative risk of 2.0). In a more rural Eastern county in 1980, a lower overall prevalence of asthma was noted. However, similar estimated relative risks of asthma (1.8) and functionally impairing asthma (2.4) were found to be associated with maternal smoking. Inconsistent relationships were found between the estimated prevalence of asthma and paternal smoking. When multivariate controls were introduced, the relationships between maternal smoking and asthma persisted. Estimated attributable risks indicate that between 18 per cent and 34 per cent of the asthma reported in these samples can be attributed to maternal smoking. Implications of these findings for primary care physicians are discussed.
Adolescent↗
New tilting disc cardiac valve prostheses. In vitro comparison of their hydrodynamic performance in the mitral position.
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Heart Valve Prosthesis↗
In vitro assessment of mitral valve prostheses.
The performance of five prosthetic mitral valves (Ionescu-Shiley, Hancock, Carpentier-Edwards, Starr-Edwards, and Björk-Shiley), all of the same nominal size (29 mm), has been assessed in a hydromechanical simulation of the left heart at three pulse rates. The mean and maximum transvalvular pressure differences, the observed and/or calculated area, and the energy loss for each valve were compared. It was found that each measure of performance rates the valves in the same order or merit, with the Ionescu-Shiley valve performing the best and the Hancock the worst among the valves tested.
Biomechanical Phenomena↗
In vitro comparison of observed and calculated mitral valve areas.
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Bioprosthesis↗
Construction and evaluation of a hydromechanical simulation facility for the assessment of mitral valve prostheses.
A hydromechanical simulator of the human left heart and systemic circulation system has been built for evaluating the dynamic actions of mitral valve prostheses. The facility includes a transparent and compliant model ventricle pumping into a simulation of the systemic circulation impedance. Transparent materials permit detailed high speed photography of valve action from the left ventricular aspect. This action has been analyzed by digitizing the valve open area and computing the variation of area with time. Additionally, pressures across and flows through the valves have been measured. Comparison has been made between the maximum observed valve open areas and the areas computed using the appropriate pressure and flow measurements substituted in clinically used equations.
Heart Valve Prosthesis↗
Potential role for P-glycoprotein in the non-proportional pharmacokinetics of UK-343,664 in man.
1. UK-343,664 is a potent and specific PDE5 inhibitor. Following single oral doses to human volunteers, it exhibited non-proportional pharmacokinetics over the dose range 30-800 mg. Over this 27-fold dose range, Cmax and AUCt increased 247- and 287-fold respectively. The half-life (4-6 h) was similar at all doses. No systemic exposure was quantifiable at doses <10 mg. 2. UK-343,664 is a lipophilic molecule (log D7.4 = 3.1) and as such is expected to be cleared mainly by metabolism. Based on studies with expressed human P450 enzymes it was concluded that the metabolism of UK-343,664 was predominantly mediated by CYP3A4. With a moderate Km = 76 microM for this enzyme, saturation of first-pass metabolism alone was considered unlikely to account for the non-proportional pharmacokinetics. 3. UK-343,664 showed high affinity for P-glycoprotein in vitro, with a Km = 7.3 microM. In transport studies in LLC-PK1 cell monolayers transfected with P-glycoprotein, UK343,664 showed marked polarized transport which was concentration dependent. 4. The high affinity of UK-343,664 for P-glycoprotein is considered to be the primary source of the non-proportional pharmacokinetic profile observed in man.
3',5'-Cyclic-GMP Phosphodiesterases↗
Pharmacokinetics and metabolism of a selective PDE5 inhibitor (UK-343,664) in rat and dog.
1. UK-343,664 is a novel potent and selective PDE5 inhibitor. Plasma clearances in the male and female rat were high (120 and 54 ml min(-1) kg(-1)), giving rise to short elimination half-lives (0.2 and 0.3h respectively). Lower clearance in dog (14 ml min(-1) kg(-1)) was the primary factor resulting in a longer elimination half-life (3.7 h). The higher clearance in rat than dog was in agreement with in vitro metabolism rates in hepatic microsomes. 2. The volume of distribution was lower in rat (1.3-2.11 kg(-1)) compared with dog (4.61 kg(-1)) probably due to increased plasma protein binding in rat (96 versus 81% in dog). 3. Oral bioavailabilities were 2, 12 and 70% in the male and female rat and dog respectively. Tmax < or = 0.5 h in all animals. 4. In multiple oral dose studies, increased systemic exposure was seen with increasing dose up to doses of 200 mg kg(-1) in rat and 150 mg kg(-1) in dog. A marked super-proportional increase in the male rat indicated a capacity-limited clearance at high doses. 5. At the maximal dose of 200 mg kg(-1) in the female rat, no clinical signs were observed after 14 days of treatment. Only minimal signs were recorded in the male rat and dog at the highest dose levels investigated. 6. After single oral or intravenous doses of [14C]-UK-343,664, the majority of radioactivity was excreted in the faeces of both species. 7. UK-343,664 was extensively metabolized in both rat and dog. The major primary pathways in dog involved piperazine N-deethylation and loss of a two carbon fragment from the piperazine ring (N,N'-de-ethylation). More extensive metabolism in the rat included additional notable metalbolites arising from hydroxylation and lactamization of the piperazine ring, which were only minor metabolites in the dog.
3',5'-Cyclic-GMP Phosphodiesterases↗
Assessing managed care for children with chronic conditions.
This paper reviews opportunities to monitor managed care for children and adolescents with chronic conditions and considers how well the Health Plan Employer Data and Information Set, version 3.0 (HEDIS 3.0), assesses care for these children. We propose four steps to strengthen the applicability of HEDIS to children with chronic conditions: (1) develop methods of identifying and monitoring groups of children with chronic conditions; (2) report HEDIS indicators for these children separately from those for other children; (3) develop and implement consumer and provider surveys that elicit information specific to these populations; and (4) develop specific structure, process, and outcomes indicators for children with chronic conditions.
Adolescent↗
Bioanalytical data in decision making: discovery and development.
1. Bioanalysis is traditionally associated with the development phase of drugs; its use in discovery programmes is often ignored but can have a major impact. 2. Pharmacokinetic studies conducted in conjunction with pharmacology screening can provide additional information to that considered in conventional structure activity relationships. Such factors as half-life and bioavailability can be critical in designing improved drugs. 3. Analytical methods in discovery programmes may differ from those used in later development work: for instance bioassay allows a common assay system for a large number of project compounds. Moreover its use, when combined with conventional methods, such as h.p.l.c., allows active metabolites to be readily detected. 4. Bioanalytical data generated in discovery and pre-clinical programmes are a valuable guide to early clinical programmes. Plasma concentration-response data from these programmes can be compared with those obtained in man. Such comparisons are particularly valuable during the phase one-initial dose escalation study. To maximize this it is our practice to generate pharmacokinetic data between each dose increase.
Animals↗
Health and special education: a study of new developments for handicapped children in five metropolitan communities.
Since the implementation in 1977 of the Education for All Handicapped Children Act (Public Law 94-142), public school systems have provided special education and related services to students with a wide range of handicapping conditions, including some children served previously in hospitals or other institutions. Although the Federal law does not require physician participation in the special education process, it does imply an active new role for the medical care community, both public and private, in helping schools to identify and diagnose children with disabilities and in ensuring that those children have adequate access to health services. This study explores the experience of five nationally dispersed urban school systems in implementing P.L. 94-142, with particular reference to the interaction of physicians and the schools. The findings highlight continued problems with early identification of certain types of childhood handicaps, classification of children's functional disorders, and adequate participation of practicing physicians in the program, especially with regard to developmental and behavioral issues. In addition, inequities in community health services are documented for a substantial number of the children studied. Improved collaboration between the health and education sectors is needed to address these concerns in order to fulfill the intent of national special education policy and to maximize the potentialities of these children and their families.
Child↗
Use and sources of payment for health and community services for children with impaired mobility.
A survey was made of the parents of 380 children whose mobility impairments require the use of a wheelchair, walker, or braces. They were asked about equipment, health services, related services, and family support services used during the previous year. There was extensive use of equipment and traditional medical and health services, such as visits to primary care and specialist physicians; there was moderate use of related health services, such as physical or occupational therapy and child counseling; and there was very little use of community-based family support services, such as respite care, after-school care, homemaker services, and summer camp. The cost of health care, particularly medical specialty care, was defrayed in large part by private insurance and public programs, such as Medicaid and Title V Programs for children with special health care needs, while financial support for related services, such as physical therapy and speech therapy, came largely through the schools. Compared to funding for health and related services, financial aid for community-based family support services is largely lacking.
Adolescent↗
The in vitro function of 19-mm bioprosthetic heart valves in the aortic position.
1. The new pericardial valves tested showed better hydrodynamic performance than the porcine and the St. Jude Medical mechanical valves. 2. The Ionescu-Shiley III valve exhibited the best hydrodynamic performance, with the least transvalvular energy loss. 3. Transvalvular energy loss shows that the major loss across the 19 mm valves occurs during the forward-flow phase. 4. Our data compares well with data from other in vitro tests performed using different test apparatus. 5. The pericardial bioprostheses, in particular, function well in the 19 mm size and therefore offer an alternative to the increased operative risk associated with valve over-sizing or orifice enlarging procedures. 6. The performance of the two porcine valves tested were comparable with each other.
Animals↗
Overview of causes and costs of injuries in Massachusetts: a methodology for analysis of state data.
Massachusetts has developed the first State profile of the causes and costs of injury based on the national study, "Cost of Injury in the United States: A Report to Congress." Incidence of fatal injuries is based on Massachusetts data; nonfatal hospitalized injuries, on Massachusetts age and sex rates and U.S. cause data; and nonhospitalized injuries, on U.S. rates applied to Massachusetts census data. Lifetime costs per injured person are based on national data adjusted for higher personal health care expenditures and for higher mean annual earnings in Massachusetts. The estimated total lifetime cost for the 1.4 million injuries that occurred in 1989 is $4.4 billion--$1.7 billion for health care and $2.7 billion for lost earnings. Injuries attributed to motor vehicles and falls account for more than half of the total cost. The other cause categories are poisonings, fire-burns, firearms, drowings-near drownings, and other. For every person who dies from an injury, 17 people are hospitalized, and an estimated 535 people require outpatient treatment, consultation, or restricted activity. Development of a State-based cost report can be useful in monitoring the contribution of injuries to health status and in planning effective injury prevention strategies in a community-based health care system. The methodology described in this paper can be replicated by other States through accessing their State-specific mortality and hospital discharge data bases.
Accidents, Traffic↗