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Biomedical subjects

D Perry

Publications and source records attributed to D Perry.

At least 37 records · Page 2Linked to original sources
PubMed2000

Myofilament lattice spacing as a function of sarcomere length in isolated rat myocardium.

The Frank-Starling relationship of the heart has, as its molecular basis, an increase in the activation of myofibrils by calcium as the sarcomere length increases. It has been suggested that this phenomenon may be due to myofilaments moving closer together at longer lengths, thereby enhancing the probability of favorable acto-myosin interaction, resulting in increased calcium sensitivity. Accordingly, we have developed an apparatus so as to obtain accurate measurements of myocardial interfilament spacing (by synchrotron X-ray diffraction) as a function of sarcomere length (by video microscopy) over the working range of the heart, using skinned as well as intact rat trabeculas as model systems. In both these systems, lattice spacing decreased significantly as sarcomere length was increased. Furthermore, lattice spacing in the intact muscle was significantly smaller than that in the skinned muscle at all sarcomere lengths studied. These observations are consistent with the hypothesis that lattice spacing underlies length-dependent activation in the myocardium.

Actin Cytoskeleton↗
PubMed2000

Psychological and social preparation for bone marrow transplantation.

Bone marrow transplantation (BMT) is a treatment for some malignant conditions which is considered both physically and psychologically demanding. This paper considers the impact of an intervention aimed at encouraging patients to be more involved in their own transplant preparation. A social research design was used to explore the psychosocial impact of BMT. Qualitative and quantitative data collection methods were used to survey 25 intervention-group and 229 comparison-group respondents. After controlling for identified confounding factors, comparisons were made between these groups. Contrary to expectation, no statistically significant differences were observed between the two groups on the outcome measures. However, when matched for categorical confounding factors, the intervention group had statistically significant improvement on "preparation," "post-transplant problems" and "anxiety" measures. The intervention group were also found to have higher scores on the "helplessness" and "fatalism" scales. The qualitative analyses suggest that this may have been due to a combination of raised expectations and non-encouraging hospital staff. Factors contributing to poor post-transplant adjustment were identified, as well as less problematic experiences common to the majority of transplant patients.

Adaptation, Psychological↗
PubMed2000

A simple effective splinting technique for the mallet finger.

We describe an inexpensive, simple, and effective technique for the closed treatment of mallet fingers. This technique splints the mallet finger in 0 degrees of extension. It is simple, readily reproducible, and easy to use, requiring materials that are readily available to any physician. Thirty-seven patients, ages 21 to 65 years, presented with a closed mallet finger injury at day zero to 5 months after injury. Ten of these patients had a fracture. All were treated with this splinting technique. We report excellent results in 35 of 37 patients, who recovered either complete or near-complete active extension. Our results compare favorably with results from other techniques and splints.

Adult↗
PubMed1999

Resolving disagreements in the patient-physician relationship: tools for improving communication in managed care.

Managed care uses financial incentives and restrictions on tests and procedures to attempt to influence physician decision making and limit costs. Increasingly, the public is questioning whether physicians are truly making decisions based on the patient's best interest or are unduly influenced by economic incentives. These circumstances lead to the potential for disagreements and conflict in the patient-physician relationship. We convened a group of individuals in October 1998, including patient representatives, leaders from health care organizations, practicing physicians, communication experts, and medical ethicists, to articulate the types of disagreements emerging in the patient-physician relationship as a result of managed care. We addressed 3 specific scenarios physicians may encounter, including allocation, illustrated by a patient who is referred to a different ophthalmologist based on a new arrangement in the physician's group; access, illustrated by a patient who wishes to see his own physician for a same-day visit rather than a nurse specialist; and financial incentives, illustrated by a patient who expects to have a test performed and a physician who does not believe the test is necessary but is afraid the patient will think the physician is not ordering the test because of financial incentives. Using these scenarios, we suggest communication strategies that physicians can use to decrease the potential for disagreements. In addition, we propose strategies that health plans or physician groups can use to alleviate or resolve these disagreements.

Communication↗
PubMed1998

Congenital factor X deficiency: spectrum of bleeding symptoms in 32 Iranian patients.

The spectrum of the clinical manifestations of congenital factor X deficiency was studied in 32 Iranian patients. The most frequent symptom was epistaxis, which occurred in 72% of patients, with all degrees of deficiency. Other mucosal haemorrhages (e.g. haematuria, gastrointestinal bleeding) were less frequent and occurred mainly in patients with unmeasurable factor X. Menorrhagia occurred in half of the women of reproductive age. Soft tissue bleeding occurred in two-thirds of the patients; spontaneous haematomas and haemarthroses led to severe arthropathy in five patients. Bleeding from the umbilical stump was an unexpected finding in nine patients. This study demonstrated that the bleeding tendency of factor X deficiency is severe and correlates with factor levels.

Adolescent↗
PubMed1998

A comprehensive approach to facilitating the recovery of cardiac surgery patients.

This article describes the cardiac surgery program at Baystate Medical Center. It emphasizes the importance of planning for the discharge process, early extubation, and structured activity guidelines and their effect on patient outcomes. The unique roles of the staff nurse, mid-level practitioner, and the clinical resource coordinator in facilitating the case management process are addressed.

Cardiac Surgical Procedures↗
PubMed1998

Range spectra in electron penetration problems.

The theory of electron penetration as predicted by the Fokker-Planck equation is first reviewed within a restricted context that considers the multiple scattering and transport of charged particles. We then broaden the context and show that range straggling effects also fit successfully into this framework, which completes an electron model initiated by Yang. We introduce those effects with a superposition of Fokker-Planck solutions, i.e., by using an incident beam that contains a spectrum of initial energies, or equivalently, a set of csda ranges. Straggling effects appear to be a beam property in this approach but are returned to the material when we use it. All the information needed to construct the spectrum is obtained from a measurement of the electron rest charge distribution in polystyrene. To illustrate the correctness of this procedure, we consider the case of a 20 MeV electron beam incident on water. We predict the absorbed dose distribution as a function of depth and also measure it with an ionization chamber in a water tank. We find nearly perfect agreement between calculation and experiment in this case where all the results derive and apply to a clinically operational machine.

Electrons↗
PubMed1998

The effect of sire breed on the melting point and fatty acid composition of subcutaneous fat in steers.

Fatty acid composition and the melting point of subcutaneous fat was determined in 18 Hereford, 25 Brahman x Hereford, 22 Simmental x Hereford, and 15 Friesian x Hereford steers that were grown out on pasture at two sites and slaughtered when the mean weight of the Herefords at each site was ca. 450 kg. Multivariate and univariate analyses tested the relations of fatty acid composition, degree of saturation, and melting point with sire breed, environment, age, and carcass characteristics. Hereford and Brahman steers were fatter than the Simmental and Friesian steers. Fat from Brahman-sired steers had a melting point 2.5 degrees C lower than fat from the Bos taurus-sired steers at the same age and had a higher proportion of unsaturated fatty acids, independent of variation in carcass weight and fatness. Melting point and degree of saturation decreased as age increased. Step-down discriminant analyses identified a set of three acids (14:0, 16:0, and 17:1) that differed among sire breeds, independent of differences in melting point: the acids 14:0 and 16:0 discriminated between Brahman and Bos taurus steers and 17:1 between Hereford and Simmental and Friesian steers. Increase in fatness was associated with an increase in 17:1, but, at the same fatness, no acids discriminated among the Bos taurus-sired steers. The use of Bos indicus cattle or their crossbreeds in situations in which hard-setting fat is likely may mitigate the problem.

Adipose Tissue↗
PubMed1998

Rapid growth in the use of automated peritoneal dialysis (APD) in adult patients on peritoneal dialysis.

Inadequate dialysis dose is associated with poor patient-survival in peritoneal dialysis (PD). Most patients would require more than four exchanges a day after losing residual renal function. The use of automated peritoneal dialysis (APD) seems to be a practical way to provide extra dialysis for these patients. In our Dialysis Centre in Northern Alberta, we started to use APD for our adult patients only from 1993. When we evaluated our practice recently, we found that we are progressively increasing the use of APD (including cyclers and night exchange devices) from 3% to 21% for our total adult PD patients in the last 3 years. This increase in the use of APD is mostly to accommodate PD prescription changes and not changes in lifestyle. Increase in the use of APD was associated with decrease in the rate of our PD dropout to hemodialysis. We conclude that to maintain adequate dialysis, rapid growth of APD will become common in North American PD centers in the future and will reduce transfer to hemodialysis.

Adult↗
PubMed1997

Bcl-2 antagonizes apoptotic cell death induced by two new ceramide analogues.

Ceramides which arise in part from the breakdown of sphingomyelin comprise a class of antiproliferative lipids and have been implicated in the regulation of programmed cell death better known as apoptosis. In the present study, two new synthetic ceramide analogues, N-thioacetylsphingosine and FS-5, were used in Molt 4 cells to induce cell death. Besides their cytotoxic effects at concentrations > or = 14 microM the data obtained clearly show that both analogues induced apoptosis at concentrations below this critical concentration as assessed by trypan blue exclusion and cleavage of the death substrate poly-(ADP-ribose) polymerase (PARP). Additional experiments in bcl-2-transfected Molt 4 cells revealed that the apoptotic but not the lytic effects of the analogues were antagonized by the apoptosis inhibitor Bcl-2. Furthermore, neither N-thio-acetylsphingosine nor FS-5 induced PARP cleavage in bcl-2-transfected Molt 4 cells indicating that the induction of apoptotic cell death by cell permeable ceramides is not due to unspecific disturbance of the cell membrane.

Amides↗
PubMed1997

Intolerance to protein hydrolysate infant formulas: an underrecognized cause of gastrointestinal symptoms in infants.

The purpose of this study was to determine the effectiveness of an amino acid-based infant formula in infants with continued symptoms suggestive of formula protein intolerance while they were receiving casein hydrolysate formula (CHF). Twenty-eight infants, 22 to 173 days of age, were enrolled; each had received CHF for an average of 40 days (10 to 173 days) and continued to have bloody stools, vomiting, diarrhea, irritability, or failure to gain weight, or a combination of these symptoms. Sigmoidoscopy with rectal biopsy was performed in all infants. The infants then received an amino acid-based infant formula, Neocate, for 2 weeks. After 2 weeks of treatment, 25 of the infants demonstrated resolution of their symptoms and underwent challenge with CHF. Of the 25 who were challenged, eight tolerated the CHF and the remainder had recurrence of their symptoms. The histologic features in these infants varied from eosinophilic infiltration to normal. We conclude that not all infants with apparent formula protein-induced colitis respond to CHF and that these infants may have resolution of their symptoms when fed an amino acid-based infant formula.

Dietary Proteins↗
PubMed1997

Analysis of swainsonine and its early metabolic precursors in cultures of Metarhizium anisopliae.

The alpha-mannosidase inhibitor swainsonine is produced by the filamentous fungus Metarhizium anisopliae. The primary metabolite pathway from which it is derived is known to be that leading to lysine. In order to effect improvements in the yield of swainsonine it is of interest to study the changes in the intracellular levels of lysine and its biosynthetic intermediates, as well as swainsonine itself, which accompany changes in culture conditions or in the genetics of the microbe. Czapek-Dox defined medium has been used for these studies. A reversed-phase, high performance liquid chromatography procedure was developed for the analysis of lysine, saccharopine, alpha-aminoadipic acid and pipecolic acid in mycelial extracts. The method is based upon precolumn derivatization with 9-fluorenylmethyl chloroformate (FMOC), a reagent known to be useful for the derivatization of amino-containing compounds. Elution with an acetate buffer/acetonitrile gradient effected separation of the four metabolites which were quantified by UV absorption at concentrations from 1 to 20 microg ml(-1). Swainsonine concentrations were determined using a previously described enzyme-based method, but applied now to intracellular as well as extracellular samples. Analysis of mycelial extracts from the end of swainsonine accumulation in medium supplemented with L-lysine revealed the accumulation of pipecolic acid and to a lesser extent lysine compared to control mycelium. Controlling the culture medium pH to 9.0 resulted in a drop in swainsonine yield accompanied by an increase in intracellular pipecolic acid levels. Spontaneous mutants tolerant to the presence of the toxic lysine analogue 2-aminoethylcysteine (AEC) were isolated in an attempt to generate lysine over-producers, which might be expected to produce more swainsonine. Surprisingly, four independently isolated mutants produced lower yields of swainsonine, but accumulated higher levels of saccharopine. The tolerance to AEC therefore appears to be due to a reduction in the diversion of saccharopine into swainsonine biosynthesis, allowing the biosynthesis of sufficient lysine to overcome AEC competition.

2-Aminoadipic Acid↗
PubMed1997

Gastroenteric inflammation in children with ulcerative colitis.

This is a retrospective review of five pediatric cases of inflammatory bowel disease with gastroduodenal as well as pancolonic inflammation. The presumptive diagnosis was Crohn's disease in all. Three of five also had microscopic ileitis. Chronic active gastritis was present at diagnosis in all five and duodenitis in four of five. None ever had noncaseating granulomas in any location. Prolonged (mean, 22 months) and ineffective trials of multiple medical therapies were carried out before subtotal proctocolectomy, which allowed the diagnosis of ulcerative colitis to be made in all children. Surgery remained curative after follow-up of over 1 yr (mean, 16 months). This experience confirms that gastroduodenal inflammation occurs in children with ulcerative colitis. Presence of gastroduodenal inflammation does not ensure the diagnosis of Crohn's unless other characteristic features of Crohn's are present. Accurate discrimination between Crohn's and ulcerative colitis remains important in management of pediatric inflammatory bowel disease to facilitate timely surgical referral. Upper gastrointestinal tract inflammation in ulcerative colitis warrants further study.

Adolescent↗