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Biomedical subjects

J Harty

Publications and source records attributed to J Harty.

17 recordsLinked to original sources
PubMed2001

Right-sided non-bacterial thrombotic endocarditis in a chronic hemodialysis patient with Muir-Torre syndrome.

Endocarditis is a recognised complication ofhemodialysis. This is generally only thought of in terms of infective vegetations. We present a case of right-sided NBTE in a patient with an indwelling venous catheter who also had advanced pelvic malignancy. The unusual side of this patient's endocarditic lesions implicates a role for the venous catheter in determining the site of non-bacterial thrombus formation. It is also a reminder that endocarditis is always a risk when using central venous catheters, even after appropriate sterile precautions have been taken.

Adult↗
PubMed1997

Impact of increasing dialysis volume on adequacy targets: a prospective study.

Failure to achieve target values for both urea (Kt/V) and creatinine clearance has been associated with increased morbidity and mortality in continuous ambulatory peritoneal dialysis patients. The conventional continuous ambulatory peritoneal dialysis regimen, which uses four 2-L exchanges per day, has resulted in up to 40% of such patients failing to achieve proposed targets for weekly Kt/V of 1.7 and weekly creatinine clearance (WCC) of 50 L. In a prospective study, the impact of increasing prescribed volumes by 0.5 L per exchange was evaluated on attaining urea and creatinine clearance targets over a 1-yr period. At 1 yr, 17 patients remaining on the increased dialysis prescription were compared with 18 patients remaining on an unchanged regimen. The mean increase in daily prescribed volume was 1.5 L (22%). This resulted in a significant increase in both peritoneal dialysis Kt/V (1.59 to 1.78 L = 12%) and peritoneal dialysis WCC (45.8 to 50.1 L = 10%) by 1 yr. Because of loss of renal function, there was no significant increase in total clearance at 1 yr, but this loss of renal clearance was offset by the gain in peritoneal clearance. Residual renal function fell at a similar rate in both the increased dialysis and control groups. In the latter, although peritoneal clearance remained stable over the 1-yr period, loss of renal function resulted in reductions in both total Kt/V and WCC. In conclusion, exchange volume can be increased to compensate for loss of renal function over a 1-yr period. Progressive loss of renal clearance resulted in only a modest gain in total solute clearance. It was the larger patients who tolerated the increase in exchange volumes. However, such patients (by virtue of their size) tended not to achieve target values for solute clearance, and the modest gain in peritoneal clearance was insufficient to increase the number of patients in this group achieving such targets for dialysis adequacy.

Adult↗
PubMed1996

The influence of small solute clearance on dietary protein intake in continuous ambulatory peritoneal dialysis patients: a methodologic analysis based on cross-sectional and prospective studies.

The statistical relationship between solute clearance (expressed as Kt/V) and dietary protein intake (DPI; estimated from the normalized protein catabolic rate [NPCR]) has led to the assumption that dialysis dose is one of the most important determinants of DPI in continuous ambulatory peritoneal dialysis patients. However, there is increasing concern about the clinical value of such a correlation between variables that contain common components. We have investigated the statistical nature of the cross-sectional correlation between Kt/V and NPCR using mathematical modelling. In addition, in a prospective study, the impact of increasing Kt/V on protein intake estimated from the NPCR and from 3-day food diaries (DPI) was evaluated in 59 patients over a 1-year period. Two thousand sets of random numbers were generated for the components, from which Kt/V and NPCR were calculated. The subsequent cross-sectional correlation between the randomly generated Kt/V and NPCR was highly significant (r = 0.64 to 0.74). In contrast, there was a much weaker cross-sectional correlation between relatively independent measures of dialysis dose (urea clearance) and protein intake measured from food diaries (r = 0.36). Analysis of the prospective relationship revealed a significant correlation with a decrease in urea clearance (due to loss of renal function) accompanied by a decrease in both PCR (r = -0.80) and DPI (r = -0.51). In contrast, when Kt/V was increased (by larger volume exchanges) there was no significant increase in protein intake. This study has demonstrated that the strength of the cross-sectional relationship between Kt/V and NPCR is due to mathematical coupling of "like with like," and this correlation cannot be used to substantiate a link between dialysis dose and nutrition. Prospective analysis does show a dependence of protein intake on urea clearance. However, this dependence is only seen in those patients undergoing a reduction in clearance due to loss of renal function. Increasing exchange volume to offset such losses was not accompanied by improvements in protein intake.

Adult↗
PubMed1996

The impact of peritoneal permeability and residual renal function on PD prescription.

Our objective was to evaluate the impact of peritoneal transport characteristics and residual renal function on peritoneal clearance and to determine the dialysis volume required to achieve targets for KT/V and weekly creatinine clearance (WCC) in patients with differing weights, renal function, and transport status. Retrospective analysis and mathematical model simulation of urea and creatinine clearance were used. This review demonstrates the important contribution of both residual renal function and peritoneal transport in attaining target values for KT/V and WCC. The limitations of a standard 4 x 2 L dialysis prescription are highlighted in anuric patients and those with low peritoneal transport. In addition, the limitations of short dwell, rapid exchange dialysis modalities are emphasized, especially in patients with low and low average peritoneal transport where daily clearance is demonstrated to be considerably less than conventional continuous ambulatory peritoneal dialysis (CAPD). Attainment of proposed targets for KT/V (1.7) and WCC (50 L) is greatly dependent on residual renal function. In CAPD, peritoneal transport characteristics determine urea clearance through an effect on ultrafiltrate. Thus low transporters of identical weight will have greater values for peritoneal dialysis KT/V. Creatinine clearance is considerably influenced by transport status. The majority of low and low average groups will need some degree of renal function to achieve currently proposed targets. In these patients, conversion to high volume, short dwell modalities will further compromise small solute clearance unless daytime long dwells or tidal dialysis is instigated.

Blood Urea Nitrogen↗
PubMed1995

Energy metabolism during CAPD: a controlled study.

Abnormalities of energy metabolism may exacerbate the high prevalence of protein-calorie malnutrition and inadequate calorie intake in continuous ambulatory peritoneal dialysis (CAPD) patients, leading to further nutritional depletion. In a controlled study, using indirect calorimetry, we evaluated oxygen consumption (VO2), CO2 production, resting energy expenditure, and respiratory exchange ratio (RER) in 12 CAPD patients at rest and during a standard CAPD exchange and in 11 healthy nonuremic control patients. In addition, we investigated the influence of nutritional status and dialysis adequacy on energy metabolism in the CAPD group. There was no significant difference in resting energy parameters between the two groups. Unlike the control group, blood glucose and RER were maintained during prolonged fasting in the CAPD patients. This observation indicates that all the absorbed glucose was used as a metabolic fuel preventing fat oxidation. There was no significant relationship between energy expenditure and dialysis adequacy. There was no significant relationship between nutritional state (including energy intake) and energy expenditure despite evidence of malnutrition in 41% of the patients. If maintenance of "normal levels" of energy expenditure occurs in dialysis patients with suboptimal calorie intake (especially with evidence of protein-calorie malnutrition), this inability to conserve energy may act as an additional risk factor for ongoing malnutrition.

Aged↗
PubMed1993

Limitations of kinetic models as predictors of nutritional and dialysis adequacy in continuous ambulatory peritoneal dialysis patients.

Nutrition has been shown to predict clinical outcome in continuous ambulatory peritoneal dialysis (CAPD) patients. However, despite the positive relationship between KT/V (urea) and the normalised protein catabolic rate, the ability of urea kinetic modelling to predict clinical outcome or nutrition remains inconclusive. We have evaluated the relationship between nutrition and achieved dialysis in a cross-sectional study of 147 stable CAPD patients on dialysis for a mean period of 22 months. Protein-energy malnutrition was present in 22-32% of the study population. 39 and 41% of the population failed to achieve suggested adequacy targets of 50 liters/week for total creatinine clearance and a weekly KT/V (urea) of 1.7, respectively. Severely malnourished patients had significantly greater normalised clearance and adequacy values than well-nourished patients. Intrinsic actual peritoneal clearance bore no relation to patient size. The subsequent normalisation of this value by a component of patient mass results in a mathematical bias against well-nourished or obese patients. This may explain the failure of such adequacy values to reflect outcome and argues against accepting such values as measures of dialysis well-being.

Body Weight↗
PubMed1991

Preliminary vascular control for renal trauma.

Preliminary control of the renal vascular pedicle prior to opening Gerota's fascia is advocated as the standard approach for decreasing the rate of nephrectomy from trauma. This method, however, has not been studied widely. Previous reports failed to grade the severity of the renal injury and involved small patient series and historic control for comparison of nephrectomy rates. We studied 297 patients with renal trauma during a ten year period. Sixty-three of 75 patients with penetrating injuries and 12 of 222 patients with blunt injuries underwent renal exploration. We obtained vascular control prior to opening Gerota's fascia in 32 patients; it was obtained in 43 patients after opening Gerota's fascia. The nephrectomy rate depended on the degree of injury rather than on the type of renal vascular control obtained. Obtaining vascular control after opening Gerota's fascia did not increase the nephrectomy rate and shortened operative time by an average of 58 minutes. We recommend vascular control after opening Gerota's fascia when there is a large hematoma crossing the midline, a rapidly expanding renal hematoma, if the patient is unstable, or if Gerota's fascia has already been opened by the injury.

Accidents, Traffic↗
PubMed1990

Polyclonal B cell activation of IgG2a and IgG2b production by infection of mice with lactate dehydrogenase-elevating virus is partly dependent on CD4+ lymphocytes.

Concentrations of IgM and IgG isotypes were determined by capture ELISA in plasma of Swiss, BALB/c and C58/M mice. Plasma IgG isotype concentrations, especially of IgM, IgG1 and IgG2a, varied considerably between mouse strains, batches of mice of the same strain and individual mice and as a function of age. Infection of the mice with LDV, which is known to replicate primarily in a subpopulation of macrophages, consistently resulted in a rapid elevation of plasma IgG2a (or of IgG2b in some Swiss nu/+ mice), but no plasma IgG increases were observed in mice immunized with inactivated LDV. Plasma IgG2a elevation after LDV infection was greatly delayed and reduced by depletion of the mice of CD4+, but not of CD8+, T cells by administration of protein-G-purified anti-CD4 or anti-CD8 mAbs, and completely inhibited by repeated treatment of the mice with cyclophosphamide. Treatment with anti-CD4 mAbs, or cyclophosphamide also greatly reduced the production of anti-LDV antibodies, while not significantly affecting the replication of LDV in these mice. Nude Swiss mice also failed to produce anti-LDV antibodies, though supporting normal LDV replication. Plasma IgM, IgG1, IgG2a and IgG2b levels increased in LDV-infected nu/nu mice, but similar changes were observed in uninfected mice. The results indicate that the LDV-induced polyclonal activation of B cells requires productive LDV infection of mice and is, at least partly, dependent on functioning CD4+ cells. They suggest that productive infection of the LDV-permissive subpopulation of macrophages leads to the activation of CD4+ T lymphocytes of subset 1 and their Spleen cells from 5-day LDV-infected BALB/c mice incorporated [3H]thymidine 2-3 times more rapidly in vitro than spleen cells from companion uninfected mice, whereas their responses to concanavalin A and lipopolysaccharide were reduced 60-70%.

Animals↗
PubMed1982

Open pelvic fractures.

Open pelvic fracture is a devastating injury with a reported 50% mortality rate from massive bleeding and pelvic sepsis. Utilizing a graded approach to management of hemorrhage that included wound packing, anti-shock trousers, angiographic embolization, and hemipelvectomy, we controlled bleeding in all but one of the 35 patients in this series. Patients lost an average of 15 units of blood. The overall survival rate was 94.5% in this series, with one death each from hemorrhage and head injury. Prevention of invasive infection by a diverting colostomy in patients with buttock wounds or perineal wounds was stressed, while anterior soft-tissue wound were managed selectively. Debridement and frequent dressing changes under anesthesia were necessary to prevent and/or treat soft-tissue infection. Associated injuries occur commonly with genitourinary and peripheral nerve trauma and account for the majority of the long-term morbidity.

Adolescent↗
PubMed1977

Ex vivo perfusion of the canine and human prostate gland.

It has been shown that the perfused canine prostate is capable of responding to pilocarpine stimulation in vitro producing prostatic secretions similar in quantity and quality to those observed in the living dog with a prostatic fistula. Furthermore, the perfused gland is capable of metabolizing testosterone. This perfusion technique has been extended to a human prostate gland harvested from a beating heart cadaver and shows the feasibility of this procedure for future studies in the human.

Animals↗