Biomedical subjects
Publications and source records attributed to S Kay.
Microsurgical reconstruction offers unique opportunities for improving function and appearance in children's hands affected by congenital anomalies or following trauma. Strong parallels exist between the surgery for congenital and post-traumatic defects. This article defines some of the methods used in replacement of skin, the creation of new digits, and the transfer of muscles.
In this article relevant key findings of a review of selected published work are used to provide a foundation for a new approach to developing a shared understanding of aspects of health care delivery. The new approach makes use of simulation models. It is hoped that this approach will provide support for improved decision-making and for the development of more appropriate enabling tools.
The CEN TC 251 Electronic Health Care Record Architecture is the first part of a four part communication prestandard intended to facilitate the safe communication of clinical information, irrespective of circumstances related to time, distance, and responsibility. The work has important implications for a diversity of stakeholders and must embody clinical principles if it is to succeed. The issue at hand is how to enable clinicians to validate the reference architecture, which is necessarily a technical document, so that they have confidence that it can meet the clinical requirement for safe communication. A model of communication that has been used to ground the architecture is shown to be useful in creating relevant clinical scenarios to permit the first steps towards coherent validation in a systematic way.
Explore the source record for details and available documents.
This is an account of the development and use of a context model for facilitating the communication of clinical information. Its function is to articulate the principle of context within a reference architecture for the Electronic Health Care Record (EHCR). The work required a re-examination of established models of communication, the purpose being to use them to support an architecture that could be reasonably expected to accommodate future, and by definition unforeseeable, developments in EHCR communication. The Context Model is built upon seven recognized constituents of communication. These constituents, although having their origin in the engineering of signal communication, have been found to be useful for explication both in the verbal and textual communication of narratives between people. The electronic health care record architecture supported by the model is the European prestandard ENV13606-1.
The pyridoxal phosphate (PLP) dependent enzyme dialkylglycine decarboxylase (DGD) specifically binds alkali metal ions near the active site. Large ions (Rb+, K+) activate the enzyme while smaller ones (Na+, Li+) inhibit it. Crystallographic results have shown that DGD undergoes a metal ion size dependent structural switch [Hohenester, E., Keller, J. W., and Jansonius, J. N. (1994) Biochemistry 33, 13561], but no evidence for multiple conformations in crystalline DGD was obtained. Here, evidence is presented that DGD-K+ in solution exists in two conformations differing in catalytic competence. Initial rate traces for DGD-K+ exhibit a high degree of curvature due to decreasing activity over time. DGD remains tetrameric under the assay conditions as demonstrated by gel filtration experiments, arguing against the possibility of subunit dissociation as the source of activity loss. Likewise, the mass spectrum of DGD shows a single covalent form. A hysteretic model that assumes two slowly interconverting enzyme forms accounts well for the initial rate data when kinetic parameters from biphasic pre-steady-state kinetics are employed. The fit of the model to the data yields an estimate of 59 +/- 1% for the fast form. A cooperative model cannot account for the data. Double reciprocal plots for coenzyme binding to DGD exhibit two linear phases. Similarly, two kinetic phases are observed in PLP association kinetics. The substitution of Na+ or Rb+ for K+ alters the steady-state kinetic parameters of DGD. Preincubation of DGD-K+ with the competitive inhibitor 1-aminocyclopropane-1-carboxylate (ACC) lowers both kcat and KAIB apparently by drawing the enzyme toward the less active, tighter binding form observed in the pre-steady-state kinetics. These results suggest that the structure of the protein around the alkali metal ion determines the conformational distribution. The transamination reaction with l-alanine was coupled in the pre-steady-state to the LDH-catalyzed oxidation of NADH. This experiment yields an estimate of 68 +/- 4% for the fast form, in agreement with the hysteretic fit to the steady-state data. The reaction of DGD with dithiobis(nitrobenzoate) was used to probe the preexisting forms of DGD. Preincubation of DGD with ACC, like the exchange of Na+ for K+, shifts the conformational distribution, in agreement with the steady-state kinetics. These experiments clearly demonstrate that DGD is a hysteretic enzyme whose conformational distribution is controlled by the identity of the alkali metal ion bound near the active site, and that cooperativity does not play a role in catalysis or regulation.
Certain phosphatidylcholine (PC) molecular species appear to be secreted into bile preferentially, but the mechanism for this selection remains obscure. We used multivariate analysis to examine the relationship between PC structure and the odds of secretion for individual PC species secreted into bile. PC was isolated from Folch extracts of bile and liver from rats, and individual molecular species of PC were quantified with reverse-phase high-performance liquid chromatography (HPLC). The odds of secretion for a given PC species were quantified as the ratio of its mole% in bile/mole% in liver. Regression analysis indicated that the odds of secretion were significantly related to length of both the sn-1 and sn-2 acyl chains (P < .0001 for both) and to relative hydrophobicity as determined by reverse-phase HPLC (P < .0001). In addition, the relationship between odds of secretion and sn-1 chain length was best described by a parabolic function. Considered together, these characteristics accounted for 88% of the observed differences in odds of secretion. This relationship between PC structure and odds of secretion was strikingly similar to the relationship between PC structure and affinity for bovine PC transfer protein. When multivariate models were used to predict both the odds of secretion and the affinity for PC transfer protein for a set of biologically plausible PC species, there was a linear relationship between the two. The likelihood of a given PC species being secreted into bile can be related to the structural characteristics of the acyl chains without having to postulate the existence of a special pool of PC destined for biliary secretion. Second, the structural characteristics that dictate selection of PC species for secretion into bile are similar to those that determine binding affinity for PC transfer protein, suggesting that the likelihood of a PC being secreted into bile is, in fact, closely related to its binding affinity for PC transfer protein (PC-TP).
PURPOSE: Anorectal diseases are common in human immunodeficiency virus-infected individuals. The aim of this prospective study was to assess the cause and clinical presentation of anorectal disease in this human immunodeficiency virus-infected population. METHODS: A registry of all human immunodeficiency virus-seropositive patients with anorectal complaints who were referred to and followed up in the colorectal surgery clinic at a county hospital was maintained, with all data collected prospectively. All patients underwent examination under anesthesia with random cultures and biopsies, along with specific sampling of any suspicious lesions. RESULTS: Data from 180 consecutive human immunodeficiency virus-seropositive patients with anorectal symptoms were analyzed. Mean age of the population was 34 years, with a male-to-female ratio of 14:1. This group comprised homosexual and bisexual males (55 percent), injection-drug users (15 percent), heterosexuals (12 percent), and others (18 percent). The average lag time from diagnosis of human immunodeficiency virus to anorectal symptoms was 48 months. The average CD4 lymphocyte count was 160 cells/mm3. The most common symptom was anorectal pain (57 percent), followed by lumps or warts (28 percent), rectal bleeding (12 percent), discharge (11 percent), and pruritus (6 percent), with 24 percent of patients having multiple complaints. Anal condyloma was the most prevalent pathology observed (43 percent), of which 10 percent was associated with anal intraepithelial neoplasia. Wide-based anal ulcers were the most frequent noncondylomatous lesions, occurring in 32 percent of patients, with the majority (91 percent) presenting with the chief complaint of anorectal pain. Some of these ulcers were associated with viral infections: herpes simplex virus (12 percent) and cytomegalovirus (7 percent). However, most ulcers were idiopathic, with negative cultures and biopsies. Other lesions encountered included fistulas (14 percent), abscesses (12 percent), hemorrhoids (6 percent), and malignancy, with two cases of Kaposi's sarcoma, one case of non-Hodgkin's lymphoma, and one case of squamous-cell carcinoma. More than one anorectal condition was identified in 16 percent of the patients. CONCLUSIONS: Human immunodeficiency virus infection is associated with a wide spectrum of anorectal disease, of which the most common lesions are anal condylomata and painful ulcers. The majority of these anal ulcers gave negative culture and biopsy results. In addition, there seems to be a high incidence of anorectal neoplasia in this patient population.
The AKR lymphoma-leukemia is a T lymphocyte neoplasm, most suitable as a model for human T cell malignancies. We have been interested in the process of tumor progression in the AKR lymphoma system. In the present study, two newly isolated variants, the TAU-42 and TAU-44, were characterized with respect to their biological behavior, by comparing them to a previously studied low-malignancy variant, the TAU-39. While the TAU-44 variant formed large s.c. local tumors, the TAU-42 variant formed only small growths or none at all. The TAU-42 lymphoma was found to have the highest malignant potential: it displayed very marked dissemination to spleen, lymph nodes, liver and lungs. The TAU-44 variant had an intermediate degree of metastatic potential but presented a predilection for spread to lymph nodes and spleen and was sometimes found to metastasize to peculiar organs, such as heart and pancreas. Cells derived from the different lymphoma variants varied in their immunophenotype: the highly malignant variant cells expressed more CD4 antigen than the low-malignancy one. The opposite was observed with regard to CD8. The variant cells also differed in their migrating capacity, the more malignant one exhibiting a higher motile activity. Studies on the tumor progression model of AKR lymphoma might contribute to the elucidation of the features determining the aggressiveness of T lymphocytic malignancies.
Transcription of Cab genes has been previously shown to be regulated by a circadian oscillator coupled to the red light-absorbing plant photoreceptor phytochrome in various plant species. In addition, it has recently been suggested that rhythmic expression of the Cab genes could also be affected by a phytochrome-independent circadian oscillator in a developmentally regulated fashion. This study has shown that a red light-insensitive oscillator and a phytochrome-coupled circadian clock indeed coregulate the oscillating expression of individual Cab genes at the level of transcription at an early developmental stage. The study involved analysing the expression patterns of transgenes, containing short fragments of the Arabidopsis thaliana Cab2 or the wheat Cab-1 promoter fused to the firefly luciferase reporter gene, by a video-imaging system in single, etiolated tobacco seedlings. Germination and red/far-red light treatments applied between 12 and 36 h after sowing lead to the appearance of two independent circadian rhythms. These rhythms coexist, both exhibiting period lengths close to 25 h but phased differently. However, repeated red-light treatments given 60 h or later after sowing synchronize these free-running rhythms and induce a single new circadian oscillation. These data indicate that both oscillators regulate the expression of the Cab genes studied at the level of transcription and that the cis-acting element(s) of the wheat Cab-1 and A. thaliana Cab2 genes mediating these responses are located on short, 250 bp promoter regions. Furthermore, these red-light induced rhythms are also inducible by far-red light treatments alone. Therefore, in tobacco, the phytochrome-coupled oscillator is regulated, at least partially, by the very low fluence response of phytochrome A.
OBJECTIVE: Vitamin D deficiency continues to be a problem in pediatrics. This report presents four children, one Caucasian male and three African-American females aged 4 to 24 months who were treated for vitamin D deficiency rickets. METHODS: One female was diagnosed in the Emergency Department during evaluation of a viral syndrome, another presented with hypocalcemic seizures and the third was a self-referral for evaluation of widened wrists. The male had biochemical rickets discovered incidentally during a hospitalization for pneumonia. All were breastfed without formula supplements. The 24-month female had severe cow and soy protein allergies and received multivitamin supplements intermittently. Birth order was from third to sixth child. Two families practiced Islam and the mothers wore veils. The females had a weight deficit for height. The females demonstrated a rachitic rosary, widening of the wrists and leg bowing. At diagnosis the serum calcium was 5.0-8.6 mg/dl, the inorganic phosphorus was 1.5-3.9 mg/dl and the alkaline phosphatase was 408-3324 U/L. The serum intact parathormone levels and the vitamin D levels were measured at Nichols Laboratories. The 25-OH vitamin D levels were 2-22 ng/ml and the 1,25(OH)2 vitamin D levels were 14-122 pg/ml. All had elevated parathormone levels. The three females had roentgenographic evidence of rickets. Two of the children also demonstrated iron deficiency. RESULTS: All patients responded to Vitamin D supplements, beginning at 2000 IU for the male and 8,000-10,000 IU daily for the females. Two children were also given calcium supplements. The three females all showed complete healing of the rickets radiologically within six months. The serum intact parathormone demonstrated an inverse correlation with the serum calcium during recovery (r=-0.669; p<0.05). CONCLUSION: Vitamin D deficiency does still occur. Breastfed children of multiparous mothers, with increased skin pigmentation, living in the higher latitudes are at increased risk and would benefit from vitamin D supplementation while breastfeeding.
BACKGROUND: Structured lipids are being incorporated into foods to reduce their energy value. One such lipid is rich in stearic acid. OBJECTIVE: The objective of this study was to compare the effects on plasma lipids of a stearic acid-rich triacylglycerol and a fat rich in palmitic acid in hypercholesterolemic subjects. DESIGN: Fifteen subjects with an average plasma cholesterol concentration of 6.13 +/- 0.80 mmol/L initially ate a low-fat diet for 2 wk (run-in period), followed in random order and blinded fashion by 2 high-fat diets (for 5 wk each) containing foods derived from margarines rich either in palmitic acid or in the structured, stearic acid-rich triacylglycerol. RESULTS: Plasma cholesterol concentrations with the low-fat, the stearic acid-rich, and the palmitic acid-rich diets were not significantly different (5.35 +/- 0.83, 5.41 +/- 0.78, and 5.52 +/- 0.68 mmol/L, respectively) but were significantly lower (P < 0.001) than those measured during the habitual diet period (ie, 2 wk before the study began). Neither HDL cholesterol nor plasma triacylglycerol differed significantly among the 3 study diets. CONCLUSION: A similar increase in the intake of stearic and palmitic acids (differing by approximately 5% of total energy) to ensure a high fat intake resulted in plasma total and LDL-cholesterol concentrations that did not differ significantly from concentrations measured during a period of low-fat intake.
The purge line is a necessary component on arterial filters, although its presence may affect the amount of flow reaching the patient as well as the pump outlet pressure in the extracorporeal circuit. In-vitro and clinical studies conducted to investigate these effects with a commonly used purge line showed that at flows less than 1.5 L/min, rates for pediatric or infant patients, the purge line diverts as much as 40% of the intended pump flow away from the patient. A small diameter resistance tube connected in series with the purge line reduced purge flow such that over 80% of the pump flow reached the patient. Pressure monitored at the arterial filter port with the purge line open could be as much as 45 mmHg lower than the pressure measured with the purge line closed to the filter. Studies should be done to determine if the arterial filter purge line compromises flow to the patient, and if an additional resistance to the purge line is appropriate to reduce the flow through it.
'Care in the Community' is an easy catch phrase but a difficult goal. It is a phrase that addresses a current growth area within health care, and one that comes complete with an impressive array of political, economic and social factors that would seem to support the notion of a continuing trend. Technology, specifically information systems, however, has not been successfully cast in a supporting role. There are many reasons for this lack of success but a major one is the mismatch between the understanding of what is required to support the clinical care processes and the specifications of the current systems supplied. Specifically the interest here is in the use and assessment of two computer science techniques, i.e. process modelling and simulation, as suitable means of capturing and communicating requirements so as to bridge the divided and power differential between users and developers of information systems.
On an individual and a population basis, an increased incidence of coronary heart disease is associated with classical cardiovascular risk factors, but many cases occur in people not identified as at high risk. Conversely, many people at high statistical risk do not develop coronary disease. We used a questionnaire to identify unrecognised coronary heart disease in people attending large-scale health survey centres. Participants were required to report the presence and characteristics of any chest pain. Those returning responses consistent with myocardial ischaemia were offered treadmill exercise ECG tests. Over 18 months, 4070 questionnaires were returned. Of 475 respondents offered testing, 229 (198 male, 131 female) accepted. Thirty-two subjects (15 male, 17 female: a detection rate of 13.9 per cent of those assessed as likely on questionnaire, or 0.8 per cent of all respondents) had results consistent with significant coronary heart disease. Follow-up was available in 30 cases. There was no difference in classical risk-factor distribution (including multivariate risk percentiles: 42.4 (male) and 46.7 (female)) between those newly diagnosed with coronary heart disease and their community counterparts. More women than men were identified as suffering from unrecognised coronary heart disease, with a preponderance of younger women. Cost per case identified was A$1220. Screening by self-administered questionnaire is a useful and relatively cost-effective means of identifying unrecognised coronary heart disease.
Explore the source record for details and available documents.
A new disposable insert for the arterial roller pump, the Better-Header, provides safety and functionality beyond what standard tubing provides. It automatically limits pump outlet pressure to a level determined by the user and provides a self-contained, simple means to set pump occlusion. The Better-Header consists of a Starling-like pressure relief valve connected across standard header tubing. As long as arterial line pressure at the pump outlet remains below a set limit, the valve is closed. If line pressure approaches the pressure limit, the valve opens, preventing overpressurization by shunting blood from pump outlet to inlet. The Better-Header can also be used to set occlusion by the "dynamic method" to obtain nonocclusive settings. The Better-Header was evaluated in the lab for its pressure-flow characteristics. Even when the arterial line was completely clamped at a pump flow of 7 L/min, line pressure was limited to a safe level and all circuit connections were preserved. The Better-Header has been used successfully at North Shore University Hospital in over 500 clinical cases covering a wide range of patients and procedures. In several instances, the user was alerted to high pressure situations by fluid flow through the valve and by an audible alarm, allowing rapid correction of the source of pressure. Compared to the standard setup, the Better-Header maintains outlet pressure within safe, user-settable limits, and permits consistent, nonocclusive settings with predictable retrograde flow.
With the introduction of large scale health information systems which are incrementally developed from legacy systems, evaluators are faced with difficult methodological and practical problems. Some of the problems involved in multidisciplinary multi-method evaluations care discussed. It is argued that the development of a framework for evaluation is necessary in order to successfully plan an evaluation, understand the implications of the results and make future predictions based upon them. Some suggestions for arriving at such a framework are put forward.