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J Stone

Publications and source records attributed to J Stone.

At least 73 records · Page 4Linked to original sources
PubMed2001

Effects of oxygen and bFGF on the vulnerability of photoreceptors to light damage.

PURPOSE: To test whether tissue oxygen levels affect the vulnerability of photoreceptors to damage by bright continuous light (BCL). METHODS: Albino rats were raised in standard conditions of cyclic light (12-hour light, 12-hour darkness) with the light level at 5 to 10 lux or 40 to 65 lux. They were then exposed to BCL (1000-1400 lux), either continuously for 48 hours or for the day or night components of the 48-hour period. During BCL, some rats were kept in room air (normoxia, 21% oxygen), some in hypoxia (10%), and some in hyperoxia (70%). Their retinas were examined for cell death, for the expression of basic fibroblast growth factor (bFGF), and for response to light (electroretinogram, ERG). RESULTS: The death of retinal cells induced by BCL was confined to photoreceptors. Within the retina, the severity of death was inversely related to the level of bFGF immunolabeling in the somas of the outer nuclear layer (ONL) before exposure. The death of photoreceptors was accompanied by an upregulation of bFGF protein levels in the ONL and by a decline in the ERG. Both hypoxia and hyperoxia during BCL reduced the photoreceptor death, bFGF upregulation, and ERG decline caused by BCL. The protective effects of hyperoxia and hypoxia were evident during both the day and night halves of the daily cycle. Hypoxia or hyperoxia alone did not upregulate bFGF or ciliary neurotrophic factor (CNTF) expression in the retina. CONCLUSIONS: Photoreceptors are protected from light damage by hypoxia and hyperoxia during exposure. The protection provided by oxygen levels operates during both day and night. The protection is not mediated by an upregulation of bFGF or CNTF.

Animals↗
PubMed2001

Serum amylase and lipase elevation is associated with intracranial events.

Serum amylase and lipase elevation has been observed in trauma patients and patients with traumatic intracranial bleeding. However, the causes of this elevation have not been clearly elucidated. A further question remains as to whether other intracranial events are associated with such enzyme elevation as well. We retrospectively reviewed 75 patients consecutively admitted to Cook County Hospital Neurosurgical Intensive Care Unit over a 3-month period for trauma, infection, tumor, or other space-occupying lesions with an unstable condition or neurological deficit. Eleven patients (15%) had elevated amylase and lipase levels. The patients were divided into two groups: Group I (n = 64) had normal and Group II (n = 11) had raised amylase and lipase levels [amylase 402 +/- 444 U/L with normal < or = 125 U/L and lipase 474 +/- 313 U/L with normal < or = 55 U/L]. All Group II patients suffered an intracranial event. Twenty-four Group I (38%) and 10 Group II (91%) patients required craniotomy (P < 0.01). No patients had clinical or radiographic evidence of pancreatitis. In summary, intracranial events are associated with serum amylase and lipase elevation probably through centrally activated pathways. Because of the lack of diagnostic value, routine pancreatic enzyme monitoring should not be performed in this patient population.

Aged↗
PubMed2001

The 2000 Canadian recommendations for the management of hypertension: Part one--therapy.

OBJECTIVE: To provide updated, evidence-based recommendations for the therapy of hypertension in adults. OPTIONS: For patients with hypertension, there are a number of lifestyle manoeuvres and antihypertensive agents that may control blood pressure. Randomized trials evaluating first- line therapy with thiazides, beta-adrenergic antagonists, angiotensin-converting enzyme inhibitors, calcium channel blockers, alpha-blockers, centrally acting agents or angiotensin II receptor antagonists were reviewed. OUTCOMES: The health outcomes considered were changes in blood pressure, cardiovascular morbidity, and cardiovascular and/or all-cause mortality rates. Economic outcomes were not considered due to insufficient evidence. EVIDENCE: Medline searches were conducted from the period of the last revision of the Canadian Recommendations for the Management of Hypertension (May 1998 to October 2000). Reference lists were scanned, experts were polled, and the personal files of the subgroup members and authors were used to identify other studies. All relevant articles were reviewed and appraised, using prespecified levels of evidence, by content experts and methodological experts. VALUES: A high value was placed on the avoidance of cardiovascular morbidity and mortality. BENEFITS, HARMS, AND COSTS: Various lifestyle manoeuvres and antihypertensive agents reduce the blood pressure of patients with sustained hypertension. In certain settings, and for specific classes of drugs, blood pressure lowering has been associated with reduced cardiovascular morbidity and/or mortality. RECOMMENDATIONS: The present document contains detailed recommendations pertaining to all aspects of the therapy of patients with hypertension, including lifestyle modifications proven to lower blood pressure, treatment thresholds, target blood pressures, choice of agents in various settings and strategies to enhance adherence. Lower thresholds for blood pressure treatment are advocated for people with other cardiovascular risk factors or established hypertensive target organ damage. Implicit in the recommendations for therapy is the principle that treatment should be individualized for each patient and the choice of agent should be dictated by coexistent conditions. For the treatment of uncomplicated essential hypertension, thiazides, beta-adrenergic antagonists, angiotensin-converting enzyme inhibitors or calcium channel blockers may be appropriate, depending on individual circumstances. VALIDATION: All recommendations were graded according to strength of the evidence and voted on by the Canadian Hypertension Recommendations Working Group. Only those recommendations achieving high levels of consensus are reported here. These guidelines will be updated annually.

Adult↗
PubMed2000

Fine-scale genetic structuring on Manacus manacus leks.

Leks have traditionally been considered as arenas where males compete to attract females and secure matings. Thus, direct fitness benefits mediated through competition between males to fertilize females have been considered to be the primary force driving the evolution of lekking behaviour. Inclusive fitness benefits mediated through kin selection may also be involved in lek formation and evolution, but to date this theory has been largely ignored. According to kin-selection theory, both reproducing and non-reproducing males may gain indirect inclusive fitness benefits. If females are attracted to larger leks, non-reproducing males add attractiveness to a lek, and therefore, in a genetically structured population, boost the reproductive success of kin. Theory predicts that the attractiveness of leks is plastic, and that males establish themselves on a lek in which the top male, in terms of reproductive success, is a close relative. Here we show that in white-bearded manakins (Manacus manacus), for which larger leks are more attractive to females and so secure the maximum number of matings, there is extraordinary fine-scale genetic structure, with leks being composed of clusters of related kin. We propose that males establish themselves where they find relatives to such an extent that they form groups within leks, and that such behaviour is consistent with kin-selection theory to maximize reproductive success of the group.

Alleles↗
PubMed2000

A randomized controlled trial of filgrastim for the treatment of hospitalized patients with multilobar pneumonia.

This study assessed the safety and efficacy of filgrastim (r-metHuG-CSF [recombinant human methionine granulocyte colony-stimulating factor]), when combined with intravenous (IV) antibiotics, in the treatment of hospitalized adult patients with multilobar community-acquired pneumonia (CAP). Four hundred eighty patients were randomized to receive placebo (n=243) or filgrastim 300 microg/day (n=237), in addition to standard therapy. Treatment with study drug was continued for 10 days, until the peak white blood cell (WBC) count reached 75x109/L, until discharge from the hospital, until death, or until IV antibiotics were discontinued. Study-related observations continued through day 29. Filgrastim increased WBC counts (baseline median, 13.3x109/L; median peak, 43. 8x109/L). The 2 treatment groups were not statistically different with respect to the study end points; however, there was a trend toward reduction of mortality in patients with pneumococcal bacteremia. Although further studies will be required to validate this observation, filgrastim was safe and well tolerated when administered to patients with multilobar CAP.

Adult↗
PubMed2000

Commercial trials using emamectin benzoate to control sea lice Lepeophtheirus salmonis infestations in Atlantic salmon Salmo salar.

Two trials were conducted at commercial salmon farms to evaluate the efficacy of emamectin benzoate (Slice, 0.2% aquaculture pre-mix, Schering-Plough Animal Health) as a treatment for sea lice Lepeophtheirus salmonis (Krøyer) and Caligus elongatus Nordmann infestations in Atlantic salmon Salmo salar L. Trials were carried out in 15 m2 commercial sea pens, at temperatures of 5.5 to 7.5 degrees C and 10.8 to 13.8 degrees C. Each pen was stocked with 14,000 to 17,500 fish with mean weights of 0.44 to 0.74 and 1.33 to 1.83 kg. Fish were naturally infested with sea lice at the start of each trial. At Day -1, samples of 10 or 15 fish were taken from each pen to determine pre-treatment numbers of lice. Emamectin benzoate was administered in feed, to 4 replicate pens, at a dose of 50 micrograms kg-1 biomass d-1 for 7 consecutive days (Days 0 to 6). Sea lice were counted again, between Days 7 and 77, and comparisons made with untreated control fish. Despite adverse weather conditions, wide variations in fish weights and exposure to new infestations, treatment was effective against chalimus and motile stages of L. salmonis. In the autumn trial, efficacy at Day 27 was 89%, and lice numbers remained lower on treated fish than on control fish 64 d from the start of treatment. In the winter trial, reductions in lice numbers at low temperatures were slower but good efficacy was achieved by Day 35. Although control fish had to be treated with hydrogen peroxide at Day 21, fish treated only with emamectin benzoate on Days 0 to 6 still had 89% fewer lice than control fish at Day 35. There were very few C. elongatus present, but at the end of both trials numbers were lower on treated fish. No adverse effects were associated with treatment of fish with emamectin benzoate.

Animals↗
PubMed2000

M11L: a novel mitochondria-localized protein of myxoma virus that blocks apoptosis of infected leukocytes.

M11L, a novel 166-amino acid membrane-associated protein expressed by the poxvirus, myxoma virus, was previously found to modulate apoptosis after infection of rabbit leukocytes. Furthermore, infection of rabbits with an M11L knockout virus unexpectedly produced lesions with a profound proinflammatory phenotype. We show here that M11L is antiapoptotic when expressed independently of other viral proteins, and is directed specifically to mitochondria by a short COOH-terminal region that is necessary and sufficient for targeting. This targeting region consists of a hydrophobic domain flanked by basic amino acid residues, adjacent to a positively charged tail. M11L blocks staurosporine-induced apoptosis by preventing mitochondria from undergoing a permeability transition, and the mitochondrial localization of this protein is essential for this function. We show that M11L is specifically required to inhibit the apoptotic response of monocytes/macrophages during virus infection, as cells of this lineage undergo apoptosis when infected with the M11L knockout virus. As monocyte apoptosis is uniquely proinflammatory, we propose that this observation reconciles the paradoxical proapoptotic and proinflammatory phenotypes of the M11L knockout virus. We suggest that apoptosis of tissue macrophages represents an important antiviral defense, and that the inhibition of apoptosis by viral proteins can be directed in a cell-specific fashion.

Amino Acid Sequence↗
PubMed2000

Prevalence of the APC E1317Q variant in colorectal cancer patients.

The notion that some common variants of APC might confer an increased colorectal tumour risk is supported by studies of the I1307K polymorphism. Recently it has been proposed that the E1317Q variant is also associated with an increased risk. We have studied the prevalence of E1317Q in 364 colorectal cancer patients and in 290 controls. Two patients were shown to possess E1317Q. Neither had a family history of colorectal cancer or co-existent adenomatous polyps. Two controls also carried E1317Q. This finding suggests that E1317Q is unlikely to be associated with anything more than a moderate increase in risk of colorectal cancer.

Adenomatous Polyposis Coli Protein↗
PubMed2000

Airflow limitation and control of end-expiratory lung volume during exercise.

To test the hypothesis that the presence of airflow limitation (AFL) influences the control of end-expiratory lung volume (EELV) during exercise, 11 subjects with normal lung function, performed submaximal exercise (SM) on a cycle ergometer, with and without AFL. AFL was achieved during exercise by increasing the density of the air via a hyperbaric chamber, compressed to a depth of 3 atm (3 ATA; with AFL). Five subjects achieved AFL during SM exercise at 3 ATA while the remaining six subjects did not achieve AFL. SM exercise was performed with the same apparatus in the hyperbaric chamber at sea level pressure with none of the subjects achieving AFL (SL; no-AFL). EELV (% of TLC, BTPS), was significantly larger during exercise at 3 ATA than during exercise at SL for the AFL group (SL = 44 +/- 6%; 3 ATA-AFL = 51 +/- 9%, P < 0.05; but, was not for the no-AFL group (SL = 46 +/- 6%; 3 ATA-no AFL = 46 +/- 7%). End inspiratory lung volume was significantly elevated during exercise at 3 ATA compared with SL in the AFL group (SL = 80 +/- 6%; 3 ATA-AFL = 86 +/- 6%; P = 0.01) but not in the no-AFL group (SL = 82 +/- 4%; 3 ATA-no AFL = 84 +/- 4%). Tidal volume and ventilation were not different for any condition. These data suggest that the occurrence of AFL influences the control of EELV.

Adult↗
PubMed2000

Urinary tract infection and patient satisfaction after flexible cystoscopy and urodynamic evaluation.

OBJECTIVES: To investigate the incidence of symptomatic and asymptomatic bacteriuria and to assess patient satisfaction after flexible cystoscopy (FC) and urodynamic (UD) evaluation in a prospective survey. The incidence of urinary tract infection after FC and UD studies and the use of prophylactic antibiotics are issues of debate. The tolerability and acceptance of FC and UD studies by patients have not been thoroughly documented. It would be helpful to be able to give such information to patients before performing these procedures. METHODS: A total of 215 nonconsecutive patients seen as outpatients for FC and UD studies to evaluate various indications were studied. A midstream urine sample was taken before and 48 hours after the procedures. Patients were given a questionnaire that inquired about the presence of lower urinary tract symptoms before and 48 hours after the procedures. The self-administered questionnaire included questions to assess patients' tolerance of the procedures and how it compared with their expectations. RESULTS: Of the 201 patients analyzed (FC 103, UD studies 98), 9 patients (4. 5%) developed significant bacteriuria within 48 hours of FC and UD studies. Only 2 patients with significant bacteriuria reported newly developed symptoms within 48 hours. In a subgroup of 25 patients who were given prophylactic antibiotics for various reasons, 6 (24%) reported new symptoms, although none developed significant bacteriuria. The association between patients who had preprocedure pyuria (n = 7) and the development of significant growth after the procedure (n = 6) was significant (P <0.01). In response to the patient-satisfaction questionnaire, 166 (82.5%) reported that the procedure was not as bad as they expected, and 200 (99.5%) said that they would undergo the test again if necessary. CONCLUSIONS: FC and UD studies are safe, well-tolerated procedures. The addition of prophylactic antibiotics in these procedures is unnecessary, unless specific indications are present.

Adult↗
PubMed2000

Ethical issues in complementary and alternative medicine.

Julie Stone is a health care lawyer and ethicist, specializing in law and ethics of the CAM relationship. She is currently a Visiting Scholar at University of Hawaii, where she is researching the interface between Western biomedicine and indigenous healing practices. As a member of a multi-centre research ethics committee, she has a particular interest in the process of ethical review and its implications for CAM.

Child↗
PubMed2000

Beyond multidisciplinary care: a new conceptual model for spina bifida services.

Medical care for people who are born with spina bifida (myelodysplasia) is complex and challenging, but the goal of such care is to optimize health and function for people with this condition. Despite years of expert agreement that multidisciplinary care is the medical standard for individuals with spina bifida, this model does not seem to go far enough towards accomplishing the goal of improved function as well as health for all people with spina bifida. Advances in the medical and surgical management of people with spina bifida and society's increased desire to include those with disabilities in family and community life has heightened our expectations for functional/participatory improvement for people with this condition. Some large spina bifida programs have added a separate rehabilitation component to the comprehensive package of services offered to people with spina bifida. The problem with adding further services to the traditional multidisciplinary spina bifida program is the increased complexity and potential for fragmentation that it presents, particularly for the patient and family. We performed a MEDLINE literature search to find information on integrating these services. Although several articles address the importance of either the multidisciplinary spina bifida clinic or a rehabilitation approach, there is little information about integration of medical and rehabilitation services. We propose a new model for spina bifida services throughout the lifespan that integrates the medical and functional/rehabilitative perspectives. Our model for conceptualizing spina bifida services builds on the WHO framework for coding disability (ICIDH-2). This framework includes not only health and functional perspectives, but a participation dimension as well. Furthermore, our new model emphasizes the importance of anticipatory guidance and transitional planning as an integrating dimension applicable across the lifespan. The model is based on three main conceptual dimensions--comprehensiveness, coordination and longitudinality. We are using the model to create standards of care, integrate services and improve their efficiency, and to develop policies regarding spina bifida services. Through this effort we hope to provide better medical and rehabilitation services to those with spina bifida and meet the complex challenge the condition presents throughout the lifespan.

Comprehensive Health Care↗
PubMed2000

Steady-state pharmacokinetics of indinavir in cerebrospinal fluid and plasma among adults with human immunodeficiency virus type 1 infection.

To characterize steady-state indinavir pharmacokinetics in cerebrospinal fluid and plasma, 8 adults infected with human immunodeficiency virus underwent intensive cerebrospinal fluid sampling while receiving indinavir (800 mg every 8 hours) plus nucleoside reverse transcriptase inhibitors. Nine and 11 serial cerebrospinal fluid and plasma samples, respectively, were obtained from each subject. Free indinavir accounted for 94.3% of the drug in cerebrospinal fluid and 41.7% in plasma. Mean values of cerebrospinal fluid peak concentration, concentration at 8 hours, and area under the concentration-time profile calculated over the interval 0 to 8 hours [AUC(0-8)] for free indinavir were 294 nmol/L, 122 nmol/L, and 1616 nmol/L x h, respectively. The cerebrospinal fluid-to-plasma AUC(0-8) ratio for free indinavir was 14.7% +/- 2.6% and did not correlate with indexes of blood-brain barrier integrity or intrathecal immune activation. Indinavir achieves levels in cerebrospinal fluid that should contribute to control of human immunodeficiency virus type 1 replication in this compartment. The cerebrospinal fluid-to-plasma AUC(0-8) ratio suggests clearance mechanisms in addition to passive diffusion across the blood-cerebrospinal fluid barrier, perhaps by P-glycoprotein-mediated efflux.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Multifetal pregnancy reduction.

Multifetal pregnancies have increased dramatically since the introduction and improvement in assisted reproductive techniques. Multifetal pregnancy reduction (MPR) is a technique developed over the past 15 years to deal with the sequelae of higher order multiple gestations resulting from infertility treatment. With increasing operator experience, loss rates for patients undergoing MPR have declined dramatically. The present review addresses recent data on the outcomes of patients undergoing MPR, as well as recent information on the natural history of higher-order multiple gestations in individuals not undergoing MPR. New developments in this area such as the use of chorionic villus sampling before MPR, as well as MPR to a single fetus, and information on the psychological follow-up of MPR patients are also discussed.

Female↗
PubMed2000

Biomechanical evaluation of occipital fixation.

Many studies have shown a positive correlation among screw pullout strength, screw insertional torque, bone thickness, and areal bone mineral density (BMD) measured by dual-energy X-ray absorptiometry. Variations are significant in the anatomy of the occipital bone. But no studies have correlated these variables with respect to the two locations commonly used for plate fixation to the occiput. The purpose of this study was to determine the thickness and quality of the occipital bone and to correlate these variables with the insertional torque of screws and the pullout strength of plates secured into two different locations on the occiput. The occiputs of 12 adult human fresh frozen cadaveric specimens were used. The specimens were analyzed by dual-energy X-ray absorptiometry. Direct thickness measurements of the occiput were performed. Areal and volumetric BMD were measured. A simple pelvic reconstruction plate (3.2 mm) was fixed to the occiput either laterally or at the midline with bicortical 4-mm cancellous screws. Torque was recorded at the time of insertion of each screw. Axial pullout tests were performed on all specimens. The peak load, failure load, stiffness, and energy to failure were recorded for each construct. Statistical analysis showed that the average thickness of occipital bone is greater in the midline than laterally. Occipital bone is thicker and screw torque is greater close to the inion. There is a positive correlation between bone thickness, areal BMD as measured by dual-energy X-ray absorptiometry, screw insertional torque, and strength of fixation. A plate fixed in the midline region of the occiput provides more rigid fixation than a plate fixed laterally. Areal BMD correlates better than volumetric BMD with bone thickness and is a reliable predictor of the strength of occipital fixation.

Absorptiometry, Photon↗
PubMed2000

Experiments on radiative collapse in laser-produced plasmas relevant to astrophysical jets

We report a laser experiment of astrophysical interest on radiative jet formation. Conically shaped targets are irradiated by intense laser light. An ablated plasma flow collides at the axis of the cone targets, then propagates at high Mach number, forming a jetlike structure. We measure time-resolved x-ray self-emission images from the jets. The diameter of the jet increases with decreasing atomic number of the irradiated target, suggesting that the collimation is due to radiative cooling. Two-dimensional simulations reproduce essential features of the experimental results.

Journal Article↗