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Biomedical subjects

J R Curtis

Publications and source records attributed to J R Curtis.

At least 73 records · Page 4Linked to original sources
PubMed1993

Race and survival time with AIDS: a synthesis of the literature.

OBJECTIVE: This study summarizes the evidence concerning the association of Black and White race with acquired immunodeficiency syndrome (AIDS) survival time. METHODS: English-language articles measuring survival time with AIDS for Black and White persons were reviewed. Each article was assigned to one of three groups based on the method of subject accrual. RESULTS: Of the nine eligible studies identified, five studies had inclusive methods of accruing study subjects, and four of these five showed decreased survival time among Black persons. In the studies with more restrictive accrual methods, survival time for Blacks was not decreased. CONCLUSIONS: Although the published studies vary in their results, this variation appears to be systematic according to the method of accruing study subjects. If the accrual method serves to minimize socioeconomic differences between Blacks and Whites, there is no difference in survival time by race. However, if a more inclusive method is used, a significant decrease in AIDS survival time is observed among Blacks. This analysis suggests that, in some studies, race may function as a marker for socioeconomic factors and/or access to health care and that AIDS patients in the lowest socioeconomic or access group have significantly shorter survival times.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Antithrombotic properties of dermatan sulphate (MF 701) in haemodialysis for chronic renal failure.

The therapeutic potential of the glycosaminoglycan (GAG), dermatan sulphate (DS), as an antithrombotic agent in humans has yet to be established. We have performed dose ranging studies of DS to determine its effectiveness as an antithrombotic agent in patients (n = 6-8) undergoing haemodialysis for chronic renal failure. In an initial study, Study 1, i.v. bolus doses of 2-4 mg/kg and 5-6 mg/kg DS were given to patients dialysing with polyacrylonitrile hollow fibre (PAN HF) membranes. In a second crossover study, Study 2, performed using cuprophane hollow fibre (CHF) membranes, i.v. bolus doses of 3 mg/kg and 6 mg/kg DS were compared to a standard unfractionated heparin (UFH) regime that has been shown previously to inhibit fibrin formation. Further infusion studies, Study 3 and Study 4 evaluated the antithrombotic efficacy of an i.v. DS bolus of 3 mg/kg plus an i.v. infusion of DS 0.6 mg kg-1 h-1 and a DS bolus of 5 mg/kg plus an infusion of 1 mg kg-1 h-1 over 5 h, respectively. These studies were compared to standard UFH regimes in a randomised crossover design. Plasma levels of fibrinopeptide A (FPA) and thrombin-antithrombin (TAT) were used as markers of fibrin formation and thrombin generation during dialysis using both membranes. The changes in DS concentration following administration of the different doses were similar in Studies 1 and 2. However, the effectiveness of DS as an anticoagulant appeared to depend markedly on the different dialyser types used in the two studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Dermatan sulphate in haemodialysis.

Experimental work suggests that dermatan sulphate has potential as an antithrombotic agent: it can inhibit venous thrombi yet has less effect upon bleeding than heparin. While heparin functions as an anticoagulant primarily by its ability to accelerate the action of the plasma protein inhibitor antithrombin III, dermatan sulphate acts selectively through a structurally related inhibitor, heparin co-factor II, to inhibit thrombin. We have done a series of dose-finding studies of the use of dermatan sulphate as an anticoagulant/antithrombotic agent in patients on maintenance haemodialysis. Dermatan sulphate proved to be an effective anticoagulant in this setting.

Dermatan Sulfate↗
PubMed1992

Prevalence of antibodies to hepatitis C in dialysis patients and transplant recipients with possible routes of transmission.

The prevalence of hepatitis C infection and possible predisposing factors was assessed in a renal unit. Of 343 patients at our renal dialysis centre, 37 (10.8%) were anti-HCV positive by a 1st-generation assay (ELISA, Ortho/Chiron) and confirmed positive in 35 (10.2%) with a 2nd-generation test (UBI, New York). Anti-HCV positivity was significantly associated with: duration of renal replacement therapy (P < 0.0001); quantity of blood transfused (P < 0.002); duration of hospital haemodialysis (P = 0.0001); duration with a functional renal transplant (P = 0.039); and aspartate aminotransferase (P < 0.0001). Logistic regression determined the following variables to be independent risk factors: duration of renal replacement therapy with a relative risk of 34.3 for 5-9 years and 87.4 when the duration was in excess of 10 years; renal transplant for less than 1 year (relative risk of 5.0); transfusion in excess of 50 units of blood (relative risk of 11.6). Clinical assessment of anti-HCV-positive patients revealed peripheral signs of chronic liver disease in 40%, hepatomegaly in 34%, and splenomegaly in 9%. This prevalence of hepatitis C infection is similar to other European and North American centres, but contrasts with low prevalence rates reported from dialysis populations in the UK. It adds further support for routine screening of blood and possibly organ donors and implementation of further infection control measures in dialysis centres.

Adult↗
PubMed1991

Dose finding study of a low molecular weight heparin, Innohep, in haemodialysis.

A pilot investigation was performed with Innohep, a low molecular weight (LMWH) preparation (peak maximum molecular mass 3,000-6,000), to determine possible dose regimens for patients undergoing regular maintenance haemodialysis for chronic renal failure. Results from this study suggested that suppression of macroscopic clot formation and fibrinopeptide A (FPA), a marker of fibrin formation, could be achieved following bolus injections rather than bolus injections and an infusion. On the basis of these preliminary findings, a randomised crossover study was performed in eight patients undergoing regular maintenance haemodialysis for 5-7 h to determine the effective antithrombotic dose of this LMWH. Single i.v. bolus doses of 1,250 AFXa u, 2,500 AFXa u and 5,000 AFXa u (n = 7-8) were compared to an UFH regime of 5,000 iu + 1,500 iu/h. Excessive clot formation in the dialyser bubble trap, necessitating additional UFH to enable completion of a prolonged (up to 7 h) dialysis, was observed in all patients on the 1,250 AFXa u dose (mean duration of dialysis prior to UFH, 3 h) but in a single patient only receiving the other LMWH doses. A dose-related response in the AFXa activity, measured by chromogenic substrate (CS) assay was seen in the three LMWH groups, with levels declining significantly (p less than 0.05) from 1-7 h. This contrasted with the constant levels maintained during dialysis with UFH. FPA levels were significantly elevated after 2 h following the 1,250 AFXa u bolus and after 4 h following the 2,500 AFXa u bolus. There was no significant difference in FPA levels between the 5,000 AFXa u bolus and UFH.(ABSTRACT TRUNCATED AT 250 WORDS)

Dose-Response Relationship, Drug↗
PubMed1991

Hemodialysis and heparin. Alternative methods of measuring heparin and of detecting activation of coagulation.

A bolus dose of heparin was administered pre-dialysis to patients (n = 6) undergoing regular maintenance hemodialysis with cuprophane flat plate and hollow fiber membranes. Blood samples were withdrawn at hourly internals for measurement of a) heparin and b) activation markers of coagulation, fibrinolysis and platelets. Two assay methods for heparin were employed; amidolytic assay of anti-factor Xa activity in plasma and a simple whole blood clotting time based upon factor Xa inhibition (Heptest). Results from these heparin assays correlated well with each other (r = 0.89) and both showed similar negative correlations (r = -0.72, amidolytic and r = -0.66, Heptest) with levels of a marker of fibrin clot formation, fibrinopeptide A (FPA). Large differences in levels of FPA were observed during dialysis with the two dialyzer types, when similar levels of heparin were present. Heparin levels declined from 1-5-h dialysis and were associated with rises in plasma levels of FPA, thrombin-antithrombin complex (TAT) and beta thromboglobulin (BTG), but not of D-dimer. Regression analysis revealed the best correlation was between FPA and TAT (r = 0.94), followed by FPA and BTG (r = 0.81). FPA and D-dimer exhibited significant, but lower (r = 0.42), correlation. TAT levels, like FPA levels, showed good correlation with heparin (r greater than 0.65). It is concluded that the Heptest assay may be a useful bedside measurement of heparin levels and the TAT assay may be a simplified means of evaluating coagulation system activation during dialysis.

Antithrombin III↗
PubMed1990

A low-molecular-weight heparin (Kabi 2165, 'Fragmin') in repeated use for haemodialysis: prevention of clotting and prolongation of the venous compression time in comparison with commercial unfractionated heparin.

We have compared a low-molecular-weight heparin (LMWH), Kabi 2165, with commercial unfractionated heparin (UFH) in 21 patients undergoing haemodialysis (1 month with each heparin). The UFH dose regimen comprised a UFH-saline prime of the extracorporeal circuit, an initial bolus of 5000 international units (IU) and an infusion of 1500 IU/h. The LMWH dose regimen comprised a LMWH-saline prime, a bolus of 3000-4000 anti-factor Xa units (aXa U) and an infusion of 750 aXa U/h. Plasma concentrations of the LMWH were slightly less than those of UFH for the first hour of dialysis (0.87 aXa U/ml vs 0.99 IU/ml) but were very similar by the end of the infusion (0.96 vs 1.00) and slightly greater at the end of dialysis, an hour later (0.85 vs 0.69). All haemodialysis sessions were completed uneventfully, with infrequent wispy clot deposits in the drip chamber. The mean frequency of clot deposition was slightly higher with the LMWH (0.20 vs 0.15). Fibrin generation was almost fully suppressed: plasma concentrations of fibrinopeptide A were slightly greater during dialysis with the LMWH (3.31-3.98 vs 2.29-2.75 pmol/ml) but were almost identical by the end of dialysis (5.62 vs 5.49 pmol/ml). The mean 'venous' compression time at the end of dialysis was significantly shorter with the LMWH than with UFH (8.45 min vs 11.12 min). We conclude that the LMWH is effective and safe in repeated use for haemodialysis. It prevents fibrin generation and clot formation to a similar degree as UFH. The shorter venous compression time of the LMWH may reflect a reduced haemorrhagic risk.

Bleeding Time↗
PubMed1990

Macroglossia and amyloidoma of the buttock: evidence of systemic involvement in dialysis amyloid.

A 48-year-old male on cuprophane haemodialysis for 18 years, with a history of dialysis arthropathy and recurrent carpal tunnel syndrome developed macroglossia and bilateral buttock tumoral masses. The tongue and buttock masses were biopsied. Histology of both biopsies showed amyloid deposits of the beta 2-microglobulin (B2M) variety. Amyloidomas in the gluteal region and macroglossia have not been previously described in amyloid derived from B2M. These findings suggest that systemic B2M amyloidosis can have a similar tissue distribution to AL amyloidosis. This case also stresses the importance of inspection of the tongue, and palpation of the gluteal region for masses, in the assessment of patients with dialysis arthropathy.

Amyloid↗
PubMed1989

Prescribing efficiently in nursing homes.

Giving medications in nursing homes is time consuming and expensive. The orders for medications in a community nursing home were examined to determine if nursing time could be saved by consolidating the administration of medications. Nineteen percent of the medication administration visits could be eliminated by this method according to the independent judgments of two physicians. This could save up to $19,000 in nursing time per year, and the time could be redirected to other nursing activities that could improve the quality of care in nursing homes.

Aged↗
PubMed1989

Survey of blood lead and plasma aluminium concentrations in patients of a renal unit.

Blood lead and plasma aluminium concentrations have been measured in patients with end-stage chronic renal failure treated by haemodialysis (HD) or by continuous ambulatory peritoneal dialysis (CAPD) and in a control group of non-dialysed patients with chronic renal failure (CRF). Data on a group of subjects with normal renal function is included for comparison. We have found significantly increased mean blood lead and plasma aluminium concentrations in all patients with chronic renal failure compared to a group with normal renal function. All blood lead concentrations were within the accepted safe exposure range of less than 1.8 mumol/l (380 micrograms/l]. There were significant differences among the patient groups: home HD, 0.60 +/- 0.25 mumol/l (124 +/- 52 micrograms/l); hospital HD, 0.39 +/- 0.31 mumol/l (81 +/- 64 micrograms/l); CAPD, 0.32 +/- 0.17 mumol/l (66 +/- 35 micrograms/l); CRF, 0.38 +/- 0.20 mumol/l (79 +/- 41 micrograms/l); normal, 0.24 +/- 0.11 mumol/l (50 +/- 23 micrograms/l). Correction of the blood lead results for haemoglobin accentuates these differences (i.e. hospital HD, 4.61 +/- 3.25 nmol/g (0.96 +/- 0.67 micrograms/g); CRF, 3.05 +/- 1.46 nmol/g (0.63 +/- 0.30 micrograms/g); normal, 1.65 +/- 0.70 nmol/g (0.34 +/- 0.14 micrograms/g). Plasma aluminium concentrations show a similar pattern: home HD, 1.09 +/- 0.70 mumol/l (29.4 +/- 18.9 micrograms/l); hospital HD, 0.81 +/- 0.58 mumol/l (21.9 +/- 15.7 micrograms/l); CAPD, 0.34 +/- 0.34 mumol/l (9.2 +/- 9.2 micrograms/l); CRF, 0.18 +/- 0.09 mumol/l (4.9 +/- 2.4 micrograms/l); normal, 0.09 +/- 0.07 mumol/l (2.4 +/- 1.9 micrograms/l).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Characteristics, diagnosis, and treatment of alcoholism in elderly patients.

The purpose of this study is to examine the ability of physicians to diagnose alcoholism in the elderly patient and to define characteristics specific to the elderly patient with alcoholism. During a 3-month period, all new admissions to the medical service of The Johns Hopkins Hospital were screened for alcoholism with two screening tests (the CAGE questionnaire and Short Michigan Alcohol Screening Test). The prevalence of screen-positive alcoholism was 27% in patients under 60 years of age and 21% in patients 60 years and older. Elderly patients with alcoholism were more likely to be black (P less than .01), but did not differ significantly in any other way from elderly patients who did not have alcoholism. Although 60% of screen-positive young patients with alcoholism were identified by their houseofficers, only 37% of elderly patients with screen-positive alcoholism were so identified (P less than .05). The elderly patients with alcoholism were significantly less likely to be diagnosed by their houseofficer if they were white, female, or had completed high school (P less than .01). Even when diagnosed, elderly patients with alcoholism were less likely than younger patients with alcoholism to have treatment recommended by their houseofficers (P less than .05) and, if treatment were recommended, it was less likely to be initiated (P less than .05). These data suggest that current medical education is deficient in providing physicians with the skills to detect and treat elderly patients with alcoholism.

Age Factors↗
PubMed1989

Acute metabolic alkalosis during haemodialysis.

A 32-year-old woman developed acute metabolic alkalosis during haemodialysis due to dialysate with a very high bicarbonate concentration. This was subsequently discovered to have been caused by the reversed connection of bicarbonate and acid concentrate containers to the entry ports of the Monitral 'S' machine and to failure of the pH meter. Recommendations are made to prevent this potentially fatal accident.

Acute Disease↗
PubMed1989

A low molecular weight heparin ("fragmin") for routine hemodialysis: a crossover trial comparing three dose regimens with a standard regimen of commercial unfractionated heparin.

In 20 hemodialysis patients using mainly flat plate dialyzers, we have conducted a controlled randomized crossover trial of three dose regimens of a low molecular weight heparin (LMWH), "Fragmin" (Kabi 2165), in comparison with a standard dose regimen of commercial unfractionated heparin (UFH) that had previously been shown to provide effective anticoagulation. The aim of the present study was to find the lowest dosage regimen of the LMWH which would be as effective as the standard UFH regimen. The UFH regimen comprised a prime with heparinized saline, an initial intravenous bolus of 5,000 international units (IU) and an infusion of 1,500 IU/h. The three LMWH regimens comprised a LMWH-saline prime, an infusion of 750 anti-factor Xa (aXa) U/h and three different bolus doses: 1) LMWH-low: 3,000 aXa U. 2) LMWH-medium: 4,000 aXa U. 3) LMWH-high: 5,000 aXa U. With the UFH regimen, plasma heparin levels of around 1.0 IU/ml were maintained during the heparin infusion, declining to 0.71 IU/ml an hour after the infusion was terminated. The LMWH-medium regimen produced very similar plasma aXa levels. The LMWH-high regimen also produced similar plasma aXa levels: therefore, it had no advantage over the LMWH-medium regimen. The LMWH-low regimen produced significantly lower levels than the other regimens during the heparin infusion (0.81-0.85 aXa U/ml, p less than 0.025). Dialysis proceeded uneventfully at all times and plasma levels of fibrinopeptide A (FPA) were suppressed well with all 4 regimens (2.77-5.74 pmol/ml) but tended to rise after the infusion was switched off (5.52-8.45 pmol/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical Protocols↗
PubMed1989

Aluminium kinetics during haemodialysis with the Redy 2000 Sorbsystem.

Aluminium kinetics of the Redy 2000 Sorbsystem using D3260 cartridges and the latest pre-treatment protocol have been studied in vitro and in vivo. In 7 patients, aluminium kinetics were studied during haemodialysis using the Redy 2000 Sorbysystem, D3260 cartridges. S557 acetate concentrate and Gambro hollow fibre dialyser (cuprophane 120M). The same patients were also studied during conventional haemodialysis using the Gambro AK10 proportionating system with acetate dialysate and Gambro hollow fibre dialyser (cuprophane 120M). There was no significant rise in plasma aluminium concentration during dialysis on the Redy 2000 Sorbsystem. The post-dialysis plasma aluminium concentrations were significantly higher after conventional haemodialysis, however, and the explanation for this is not clear but is not accounted for by differences in the degree of ultrafiltration during the studies. A significant rise in dialysate aluminium concentration was observed after 4 hours of dialysis on the Redy 2000 Sorbsystem. The manufacturer's ammonia test papers appear to be too insensitive as indicators of cartridge exhaustion and dialysate pH may be better. The D3260 cartridges should be used for a maximum of 4 hours only. Further long-term studies of aluminium kinetics using this system are justified.

Aluminum↗
PubMed1988

Low molecular weight heparin in haemodialysis for chronic renal failure: dose finding study of CY222.

A dose finding study of the very low molecular weight heparin CY222 (MW 2500) in patients (n = 8) with chronic renal failure undergoing dialysis has been carried out to (i) establish an effective dose and (ii) determine the relationship between ex vivo anti-factor Xa levels in plasma and the anticoagulant effect (in vivo suppression of FPA levels). Doses of CY222 were compared to a dose (5000 iu bolus + 1500 iu/hr) of unfractionated heparin (UFH) that has been shown to suppress FPA levels during prolonged (greater than 5 hr) dialysis (Ireland et al., J Lab Clin Med 103, 643, 1984). CY222 given iv in increasing doses produced a dose related increase in anti-factor Xa levels (measured as Institute Choay u/ml, with CY222 itself as standard) and suppression of FPA levels. When given in its highest dose, 20,000 Institute Choay u bolus + 1500 Institute Choay u/hr, there was little effect upon KCCT, FPA levels were statistically indistinguishable from those of the UFH regime (indicating comparable anticoagulant effect), but anti-factor Xa levels (expressed in Institute Choay u/ml) were 2-3 times those of UFH (expressed in iu/ml). All samples were also assayed for anti-factor Xa level against the proposed low MW Heparin Standard. Plasma levels of CY222 were then found to be 2.78 times lower, so that the anti-factor Xa levels of CY222 required to produce comparable anticoagulant effect were then indistinguishable from those of UFH.(ABSTRACT TRUNCATED AT 250 WORDS)

Drug Evaluation↗