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Biomedical subjects

J S Gill

Publications and source records attributed to J S Gill.

At least 19 recordsLinked to original sources
PubMed2007

The importance of transitions between dialysis and transplantation in the care of end-stage renal disease patients.

Analyses describing outcomes of kidney transplantation usually exclude the survival of wait-listed patients and dialysis patients with failed kidney transplants, and thus reflect only a portion of the typical transplant process. We determined death rates during the continuum of wait-listing, transplantation, and after allograft failure among adult end-stage renal disease patients in the United States between 1995 and 2003. Before transplantation, death rates increased with longer waiting times. Death rates were lowest during the period of allograft function and highest after allograft failure. Patients were at particularly high risk during periods of transition between dialysis and transplantation (death rates during the peri-transplant period and during the re-initiation of dialysis after transplant failure were 8.2/100 patient-years (95% confidence interval (CI) 7.7, 8.8) and 17.9/100 patient-years (95% CI 15.7, 20.3), respectively compared to 6.4/100 patient-years (95% CI 6.25, 6.51) during the period of wait-listing. Diabetic patients and older patients were at increased risk at all time points. The most common known cause of death in all age subgroups was cardiovascular disease. The proportion of death owing to sepsis was greatest after allograft failure (16.8% of all deaths were due to sepsis compared to 14.0% during wait-listing, and 12.7% during the period of allograft function). Consideration of the entire transplant experience as a whole should help to focus patient care on periods of particularly high risk, and emphasizes opportunities to improve outcomes by strategies aimed at preventing death owing to cardiovascular and infectious causes.

Adolescent↗
PubMed2007

Epoetin use and Kidney Disease Outcomes Quality Initiative hemoglobin targets in patients returning to dialysis with failed renal transplants.

Patients with failed renal transplants represent an increasing proportion of the current dialysis population. Although their risk of anemia might be expected to be high, whether these patients receive adequate anemia therapy after returning to dialysis is unknown. We studied intravenous iron use, epoetin doses, and hemoglobin levels in patients with and without failed renal transplants who survived for 6 months after initiation of dialysis in the United States between 1996 and 2001. Of the study population (n=220 557), 9922 (4.5%) had failed renal transplants. In spite of a greater likelihood of receiving intravenous iron therapy (adjusted odds ratio (AOR) 1.47, P<0.0001) and epoetin (AOR 1.57, P<0.0001), patients with failed transplants were more anemic and had higher epoetin doses in each month of follow-up. During month 6, patients with failed transplants were more likely to have hemoglobin levels below 11 g/dl (AOR 1.50, P<0.0001) and to have epoetin-to-hemoglobin ratios above the population median of 1030 U/week per g/dl (AOR 1.73, P<0.0001). Patients who return to dialysis with failed transplants are at a higher risk of anemia than other patients who start dialysis; the pattern of lower hemoglobin levels and higher ratios of epoetin-to-hemoglobin suggests that relative epoetin resistance may be contributory.

Adolescent↗
PubMed2006

Association between residence location and likelihood of kidney transplantation in Aboriginal patients treated with dialysis in Canada.

For reasons that are not well understood, Aboriginal people with end-stage renal disease (ESRD) have lower rates of kidney transplantation. We hypothesized that distance between residence location and the closest transplant center was greater in Aboriginal dialysis patients and would partially explain the lower rate of transplantation in this population. We studied a random sample of 9905 patients initiating dialysis in Canada between 1990 and 2000. We calculated the distance between residence location at dialysis inception and the closest transplant center. Cox proportional hazards models were used to examine the relation between residence location and the likelihood of transplantation over a median period of 2.3 years. The proportion of Aboriginal participants living 300 km from the closest transplant center was 25, 18, 18, and 39% respectively, compared with 55, 19, 11, and 15% among white subjects. The relative likelihood of transplantation was significantly lower for Aboriginal compared to white participants across all four distance strata, with no apparent effect of residence location. For example, the relative likelihood of transplantation was hazard ratio (HR) 0.47, 95% confidence interval (CI) (0.31-0.72) in Aboriginal participants residing 300 km from the closest transplant center. Results were similar for transplants from deceased donors and living donors, and in all seven regions studied. In conclusion, remote location of residence does not explain the lower rate of kidney transplantation among Aboriginal people treated for ESRD in Canada.

Aged↗
PubMed2006

Potential advantages and limitations of applying the chronic kidney disease classification to kidney transplant recipients.

The National Kidney Foundation (NKF) Kidney Disease Outcomes Quality Initiative (K/DOQI) classification of Chronic Kidney Disease (CKD) characterizes patients by their level of kidney function and includes kidney transplant recipients (KTRs). Most KTRs have stage > or = 3 CKD (estimated glomerular filtration rate < 60 mL/min/1.73 m2) and may benefit from aggressive CKD care. Recent modifications to the K/DOQI CKD classification reflect the recognition of KTRs as a unique subset of CKD patients in whom the presentation, progression and implications of CKD may vary from those in nontransplant CKD populations. Currently, there is limited information about how adopting the CKD classification in KTRs will influence clinical management and outcomes. Appropriately designed studies are needed to develop transplant-specific CKD treatment recommendations, and to ensure patient, health provider and payer acceptance of the continued need for aggressive CKD care after transplantation. Education and implementation strategies will be required to ensure appropriate integration of the CKD classification and treatment guidelines into existing posttransplant care programs. The CKD classification thus represents an exciting potential strategy to improve clinical outcomes that should be adopted, further studied and modified to incorporate considerations unique to KTRs.

Cardiovascular Diseases↗
PubMed2004

Non-contact left ventricular endocardial mapping in cardiac resynchronisation therapy.

BACKGROUND: Up to 30% of patients with heart failure do not respond to cardiac resynchronisation therapy (CRT). This may reflect placement of the coronary sinus lead in regions of slow conduction despite optimal positioning on current criteria. OBJECTIVES: To characterise the effect of CRT on left ventricular activation using non-contact mapping and to examine the electrophysiological factors influencing optimal left ventricular lead placement. METHODS: and results: 10 patients implanted with biventricular pacemakers were studied. In six, the coronary sinus lead was found to be positioned in a region of slow conduction with an average conduction velocity of 0.4 m/s, v 1.8 m/s in normal regions (p < 0.02). Biventricular pacing with the left ventricle paced 32 ms before the right induced the optimal mean velocity time integral and timing for fusion of depolarisation wavefronts from the right and left ventricular pacing sites. Pacing outside regions of slow conduction decreased left ventricular activation time and increased cardiac output and dP/dt(max) significantly. CONCLUSIONS: In patients undergoing CRT for heart failure, non-contact mapping can identify regions of slow conduction. Significant haemodynamic improvements can occur when the site of left ventricular pacing is outside these slow conduction areas. Failure of CRT to produce clinical benefits may reflect left ventricular lead placement in regions of slow conduction which can be overcome by pacing in more normally activating regions.

Adult↗
PubMed2004

Detection of human blood in the bat tick Carios (Ornithodoros) kelleyi (Acari: Argasidae) in Iowa.

The argasid tick Carios (Ornithodoros) kelleyi Cooley & Kohls is a common ectoparasite of bats and has been found in massive numbers in homes with associated bat colonies in eastern Iowa. This tick feeds nearly exclusively on bats in nature. Several inhabitants of infested homes complained of "bug bites" at night while asleep that may have resulted in erythematous, edematous, urticaric skin lesions and constitutional signs and symptoms. We provide laboratory evidence that a single, engorged C. kelleyi nymph contained host blood from a human female. The clinical implications of our findings are intriguing but unclear.

Animals↗
PubMed2002

Beneficial effects of biventricular pacing in a patient with hypertrophic cardiomyopathy and intraventricular conduction delay.

The beneficial use of biventricular pacing is reported in a patient with hypertrophic cardiomyopathy and intraventricular conduction delay. This resulted in improvements in symptomatic status and exercise tolerance that may be related to cardiac resynchronisation. The improvement in symptoms by biventricular pacing in a patient with hypertrophic cardiomyopathy and intraventricular conduction delay is previously undocumented and requires further investigation.

Arrhythmias, Cardiac↗
PubMed2002

The implantable cardioverter defibrillator.

The implantable cardioverter defibrillator is the optimal treatment for both primary and secondary prevention in patients with previous aborted sudden death and with life-threatening cardiac arrhythmias. This article will review the indications and the evidence supporting implantable cardioverter defibrillator use.

Arrhythmias, Cardiac↗
PubMed2002

Atrial fibrillation current and future treatments: radiofrequency ablation and novel pacing techniques.

Atrial fibrillation (AF) is a common clinical arrhythmia with significant symptomatology and is associated with an increased risk of systemic embolic events. Until recently, the treatment options for AF were essentially pharmacological. Recent developments in the understanding of the mechanisms of AF have resulted in a series of non-pharmacological treatments becoming available. Such treatments include surgical 'maze' procedures and, more recently, the introduction of radiofrequency ablation techniques within the atria to prevent fibrillation. Complex pacing procedures, including multisite and biatrial pacing, have been used to treat AF. Tailoring treatment for individual patients is a complex task and this review will attempt to rationalise the non-pharmacological treatment paths for individual patients with AF.

Atrial Fibrillation↗
PubMed2001

Suramin-induced neuropathy in an animal model.

Suramin is being used either alone, or in combination with other chemotherapeutic agents, in the treatment of hormone-refractory or metastatic prostate cancer. Use of this potentially valuable chemotherapy is limited by a dose-dependent polyneuropathy. It has been difficult in human studies to characterize peripheral suramin toxicity separately from cancer-related neuropathy. To characterize suramin-induced neuropathy in a rat model, adult rats were given either a single dose of 500 mg/kg (high dose) or 50 mg/kg (low dose) weekly suramin for 2 months. Electrophysiology and peroneal/sural nerve morphometry were performed. In high dose animals, neuropathy developed within 2 weeks, most severe in the digital sensory responses (DSR) (p<0.05) and tail and hind limb compound muscle action potential (p<0.001). Histologically, there was evidence of axonal degeneration and axon atrophy. With low dose suramin, the DSR (p<0.05) and tail distal sensory and motor responses (p<0.01) were most severely affected at 2 months. Axonal degeneration was seen in teased fibers from most animals. With TEM, there were abundant characteristic lysosomal inclusion bodies in DRG and Schwann cells. Electrophysiological and histological evidence of peripheral demyelination was rare, being observed in only one animal. Suramin induced a length, dose and time-dependent axonal sensorimotor polyneuropathy associated with axonal degeneration, atrophy, and accumulation of glycolipid lysosomal inclusions.

Animals↗
PubMed2001

Atrial arrhythmia suppression by atrial overdrive pacing: pacemaker Holter assessment.

The purpose of this study was to assess the efficacy of overdrive, single-site right atrial appendage pacing to reduce the burden of atrial fibrillation (AF) when compared with a standard lower rate limit of 60 bpm. This was verified by using the pacemaker's Holter. Eighteen subjects with a pre-implant history of paroxysmal AF and implanted DDDR mode-switching pacemakers were recruited. The pacemaker lower rate limit was programmed in random order to 60, 75 or 90 bpm for three 2-month periods and the amount of AF quantified. In addition, the exercise tolerance (ET), general well being (GWB), functional capacity (FC) and specific symptom prevalence (SSP) were assessed. The main finding of the study was that when ranked according to the amount of AF, there was no significant difference in the amount of AF according to the pacing rate. Six patients failed to tolerate pacing at 90 bpm. There were no differences in the ET, GWB, FC and SSP scores. It is concluded that those clinicians that manage patients with paroxysmal

Adult↗
PubMed2000

Ceramide initiates NFkappaB-mediated caspase activation in neuronal apoptosis.

The objective of the present study was to evaluate the role of ceramide in mediating apoptosis of dorsal root ganglion neurons induced by either nerve growth factor withdrawal or treatment with the chemotherapeutic agents suramin and cisplatin. Measurement of ceramide accumulation by mass spectrometry and the diacylglycerol kinase assay revealed elevation of intracellular ceramide only in suramin treated cultures. Ceramide-mediated neuronal cell death was inhibited by the caspase inhibitor zVAD.fmk. In these experimental models, ceramide accumulation mediated activation and nuclear translocation of the transcription factor NFkappaB and cyclin D1 protein expression. Specific inhibition of NFkappaB using a molecular decoy strategy resulted in increased cell viability accompanied by diminished caspase activity and cyclin D1 expression. Inhibition of NFkappaB did not alter intracellular ceramide levels. Our study suggests that ceramide generation occurs upstream of NFkappaB activation, cell cycle reentry, and caspase activation in the neuronal death pathway.

Animals↗
PubMed2000

Reversible cardiomyopathy after radiofrequency ablation of lateral free-wall pathway-mediated incessant supraventricular tachycardia.

Incessant supraventricular tachycardia leading to reversible cardiomyopathy has been reported. Cardiomyopathy usually only develops after prolonged episodes of tachycardia at a significant heart rate. Left ventricular free-wall pathways rarely cause fast and incessant tachycardia. Therefore cardiomyopathy has not been reported with left ventricular free-wall pathway-mediated supraventricular tachycardia. We report on two cases of left ventricular free-wall-mediated supraventricular tachycardia leading to reversible cardiomyopathy after radiofrequency ablation. These cases illustrate the difficulty in diagnosing tachycardia-mediated cardiomyopathy, as the tachycardia may be clinically silent. In addition, they emphasize the importance of making this diagnosis, as the cardiomyopathy is reversible.

Adult↗
PubMed1998

Paracrine production of nerve growth factor during rat dorsal root ganglion development.

Nerve growth factor is a target derived growth factor. In the peripheral nervous system, it is produced by tissues innervated by the sympathetic nervous system and small sensory neurons. In the present study, we tested the hypothesis that an alternate source of nerve growth factor must be available to support dorsal root ganglion neurons before they make connection with the target. Using reverse transcriptase polymerase chain reaction (RT-PCR), we detected nerve growth factor mRNA at embryonic day 12 to 17, but not in adult dorsal root ganglia. In situ hybridization studies revealed positive staining in satellite/supportive cells juxtaposed to dorsal root ganglion neurons. Our study suggests that nerve growth factor from supporting cells may have a paracrine function during development of primary sensory neurons.

Animals↗