Biomedical subjects
N Wilson
Publications and source records attributed to N Wilson.
Withdrawing very low-burden interventions in chronically ill patients.
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Report of "subclinical aortic perforation" with the infant double-button (Sideris) patent ductus occluder was most likely operator related.
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Amplatzer device closure of a residual aortopulmonary window.
Significant residual defects after surgical closure of aortopulmonary windows have previously required re-operation. In this paper, we describe the use of a custom made Amplatzer closure device to occlude a hemodynamically significant defect in a 5-year-old child. The device was successfully deployed without complication, and resulted in a major reduction in aorto-pulmonary flow.
Interventional treatment of lateral tunnel dehiscence in a total cavopulmonary connection using a balloon expandable covered stent.
In this paper we present a patient with dehiscence of an intra-atrial tunnel previously constructed during a total cavopulmonary connection procedure. We describe the use of a custom made covered stent to seal off the dehisced segment, and abolish the intra-cardiac shunting. We believe this is the first account of such a procedure being undertaken.
Implementing capitation of Medicaid mental health services in Colorado: is "readiness" a necessary condition?
Two consortia of community mental health centers in Colorado varied in their administrative readiness for changing to a capitated system and, ultimately, implemented capitation using different organizational arrangements. The objective was to assess the impact of this natural experiment on administrative change, costs, and utilization of services during the first two years postcapitation. Prior to capitation, one was rated as having greater "readiness" than the other and received a capitation contract from the state, while the other did not. A private, for-profit managed behavioral health organization was awarded a contract and formed a joint venture with the less "ready" consortium, providing managed care expertise to complement the consortium's expertise in delivering mental health services. Two years later, these consortia do not look different either administratively or in their patterns of service utilization and costs. These findings suggest alternative ways of successfully implementing a capitated public mental health system.
Anthracycline induced cardiomyopathy: successful treatment with angiotensin converting enzyme inhibitors.
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Cryosections of pre-irradiated adult rat spinal cord tissue support axonal regeneration in vitro.
Neonatal X-irradiation of central nervous system (CNS) tissue markedly reduces the glial population in the irradiated area. Previous in vivo studies have demonstrated regenerative success of adult dorsal root ganglion (DRG) neurons into the neonatally-irradiated spinal cord. The present study was undertaken to determine whether these results could be replicated in an in vitro environment. The lumbosacral spinal cord of anaesthetised Wistar rat pups, aged between 1 and 5 days, was subjected to a single dose (40 Gray) of X-irradiation. A sham-irradiated group acted as controls. Rats were allowed to reach adulthood before being killed. Their lumbosacral spinal cords were dissected out and processed for sectioning in a cryostat. Cryosections (10 microm-thick) of the spinal cord tissue were picked up on sterile glass coverslips and used as substrates for culturing dissociated adult DRG neurons. After an appropriate incubation period, cultures were fixed in 2% paraformaldehyde and immunolabelled to visualise both the spinal cord substrate using anti-glial fibrillary acidic protein (GFAP) and the growing DRG neurons using anti-growth associated protein (GAP-43). Successful growth of DRG neurites was observed on irradiated, but not on non-irradiated, sections of spinal cord. Thus, neonatal X-irradiation of spinal cord tissue appears to alter its environment such that it can later support, rather than inhibit, axonal regeneration. It is suggested that this alteration may be due, at least in part, to depletion in the number of and/or a change in the characteristics of the glial cells.
Abnormal responses for blood pressure in children and adults with surgically corrected aortic coarctation.
BACKGROUND: Despite successful surgical repair of aortic coarctation, life expectancy is reduced, and up to one-third of patients remain or become hypertensive. So as to characterize the responses for blood pressure, we have studied 55 patients with surgically repaired coarctation. Their mean age was 11.3 +/- 5.97 years. We documented maximal uptake of oxygen, anaerobic threshold, plasma renin activity and blood pressures during a Bruce protocol treadmill test. The velocity across the site of repair as imaged by cross-sectional echocardiography was measured before and after exercise. We measured the changes in heart rate and blood pressure subsequent to an infusion of 1 ug per kg of isoprenalin, monitoring blood pressure over 24 hours in all patients. RESULTS: When compared with 40 healthy age-matched controls, the patients with coarctation had a normal exercise capacity. Resting systolic blood pressures above the 95th percentile were present in 45% of the patients. Exercise-induced hypertension, and an elevation in the average systolic 24 hour blood pressures, were observed, but less frequently than elevated baseline values, suggesting that so-called white-coat" hypertension may be present in this population. Abnormal reactions and elevation of plasma renin activity were related to a history of paradoxical hypertension at the time of surgery. Attenuation of the circadian rhythm for blood pressure was a frequent finding, and may have implications in the development of long-term damage to end-organs. A high correlation was found between mean systolic blood pressure measured by 24 hour monitoring and left ventricular hypertrophy (r=0.65, p<0.05). CONCLUSIONS: Abnormalities in blood pressure occurred independently of significant mechanical obstruction. Despite successful surgical repair, abnormalities in the shape of the aortic arch, reduced sensitivity of baroreceptor reflexes, and neurohumoral factors may all contribute to the development of hypertension.
A psychoanalytic contribution to psychic vampirism: a case vignette.
In conclusion, the vampire is a complex symbol of the voracious, ambiguous, horrific, transformed, and transforming, early mother figure. What may cause a regressive reaction leading to loss of object constancy? In this study I have addressed a specific physical transformation of the mother that created profound anxiety in her child. This experience can be felt as horrific. An emotional deadening may be another response. We are all susceptible to anxiety stemming from some loss of object constancy. Mr. A. certainly suffered from this phenomenon: witness his need to experience me as always available and sustained. He experienced his mother as an elusive, vague entity. We can only conjecture that his very early, preverbal upbringing was similarly experienced. To some extent, we were all exposed to some element of imperfect, inconsistent mothering. This reality, along with the other previously mentioned variables, could make us all vulnerable to vampiric anxieties. Also, I have suggested that these infantile experiences of frightening changes in the transformed mother, who may be felt as draining the life from the child, can become the basis for an organizing fantasy and lead to type of object-relating that is self-sacrificing to an extreme--a masochistic yielding to a severely demanding object. Through identification with that object a demanding, insatiable quality is acquired. Finally, this form of early experience is, perhaps, so much a part of human experience that it has become the basis of a myth of universal proportions.
Hyperthermia to normal human skin in vivo upregulates heat shock proteins 27, 60, 72i and 90.
This study was performed to test the hypothesis that expression of heat shock proteins (HSPs) exhibits a spatially selective response within intact human skin following in vivo exposure to thermal stress. This response is believed to protect cells and tissues from further damage. Using Western blotting and immunohistochemistry, we studied the expression of a range of HSPs in normal human skin of 5 subjects prior to and following heating in vivo. The skin was heated to 41 +/- 0.5 degrees C for 1 h and biopsies were taken at 4, 8 and 24 h and from control, untreated skin. HSPs 27, 60, 72i, 90, 110 and heat shock constitutive (HSC)70 were expressed in normal skin, but the extent and distribution of these HSPs showed considerable variation. HSP27, 60 and 72i were found predominantly in the epidermis, whereas HSC70 showed weak epidermal staining but strong dermal expression. Heating the skin in vivo resulted in an increased skin content of HSP27, 60, 72i and 90, with maximal increase at 24 h following hyperthermia, while the skin content of HSC70 and HSP110 were unchanged. Significant increases in the content of HSP72i and HSP90 had occurred by 4 h following hyperthermia, with a mean +/-SEM of 206 +/- 50% and 197 +/- 38% of the control, untreated values, respectively (p<0.05). These findings indicate the complexity of HSP dynamics in human skin, and suggest that heating within the experimental range may protect the skin from further stresses for at least 24 h.
Copulating with multiple mates enhances female fecundity but not egg-to-adult survival in the bruchid beetle Callosobruchus maculatus.
Postcopulatory sexual selection theory has come a long way since the evolutionary implications of sperm competition were first spelled out by Parker (1970). However, one of the most enduring questions remains: why do females copulate with multiple males? Here we show that females copulating with multiple males lay more eggs than those copulating repeatedly with the same male. We also show egg-to-adult survival to be more variable when females copulate multiply with different males and less variable when they copulate multiply with the same male. This supports the notion that egg-to-adult survival may depend on the genetic compatibility of males and females. However, pre-adult survival was highest when females copulated repeatedly with the same male rather than with different males. Thus, it would appear that polyandry in this species does not function to reduce the risk of embryo failure resulting from fertilization by genetically incompatible sperm.
Images in cardiology. Exclusion of a pulmonary artery aneurysm using a covered stent.
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Inflammatory markers in clinical practice.
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Ectoparasitic insects of bats in British Columbia, Canada.
One species of parasitic bug (Hemiptera : Cimicidae), 3 species of fleas (Siphonaptera: Ischnopsyllidae), and 2 species of parasitic flies (Diptera : Nycteribiidae) were collected from 9 species of bats (Chiroptera : Vespertilionidae) in southern interior and northeastern British Columbia, Canada. Female bats that return daily to maternity roosts were more frequently infested with both cimicids and ischnopsyllids than were male bats. Some differences in ectoparasite infestation can be attributed to differences in roosting behavior of the host. New national records for 2 parasite species, and 8 new host records are established for Canada.
Helex Septal Occluder for Closure of Atrial Septal Defects.
The HELEX Septal Occluder (W.L. Gore and Associates, Flagstaff, AZ) is a new device with many desirable characteristics. These include direct placement of the delivery catheter across the septal defect without the need for a long sheath; rounded, flexible and atraumatic shape; easy deployment while maintaining the ability to withdraw the device back into the delivery system at any time prior to release; safety cord to allow for removal of the device even after release from the formed elements of the delivery system; and highly biocompatible expanded polytetrafluoroethylene (ePTFE) covering. The design of the device has been thoroughly tested by computer modeling, in vitro testing, and in vivo evaluations in an animal model of atrial septal defect (ASD). Early human experience in Europe for ASD and patent foramen ovale (PFO) indications has been encouraging. Food and Drug Administration (FDA) trials in the United States are anticipated this year.
Criteria for disposable brush tips for use in dentistry.
PURPOSE: The purpose of this paper is to document criteria considered appropriate for disposable brush tips used to apply agents in liquid and gel form and to carry out an assessment of examples of brush tips supplied by manufacturers of dental materials. MATERIALS AND METHODS: Three brush tips were selected at random from sixteen packs of dental materials and one dedicated pack of brushes, and examined under 4X magnification. The brush tips were assessed with regard to criteria such as cost, flexibility, shape, size, etc to determine, in particular, whether any correlation existed between brush tip characteristics and the type (i.e., fluid or gel) and thickness of agent to be applied. RESULTS: When assessed with regard to the ideal criteria, no correlation was apparent between brush tip features and the type and thickness of agent to be applied. CONCLUSION: It is suggested that brush tip effectiveness may be found to be dependent upon the correct choice of tip shape, length, and size for each particular function, and that operators and manufacturers alike should choose the brush tip considered most suitable for any given application. Before application of a given material, clinicians should select the brush tip to be used to ensure that the appropriate amount of material will be applied in the intended thickness.
Socio-demographic characteristics of New Zealand smokers: results from the 1996 census.
AIMS: To examine the key socio-demographic characteristics of adult smokers in New Zealand based on 1996 census data. METHODS: Data were obtained from the 1996 Census of Populations and Dwellings on smoking status and key socio-demographic variables. Age standardised smoking prevalence rates were calculated. RESULTS: Of the New Zealand population aged 15 years and over, 23.7% reported that they were regular smokers. Maori have the highest smoking prevalence in New Zealand (40.5%) and the peak rate is 55% among young Maori women aged 25-29 years. Pacific Island people, particularly males, have higher smoking rates than Europeans, while among Asians, the rate for males is three to four times the rate for females. People with no qualifications, who are unemployed or earning less than $30,000 per year, and women with high parities also have relatively high smoking prevalence rates. CONCLUSION: The smoking rates of New Zealand population groups are highly heterogeneous and there is substantial scope for focusing tobacco control interventions on those groups with the highest prevalence.