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Biomedical subjects

C W McIntyre

Publications and source records attributed to C W McIntyre.

At least 19 recordsLinked to original sources
PubMed2003

Biofeedback controlled hemodialysis (BF-HD) reduces symptoms and increases both hemodynamic tolerability and dialysis adequacy in non-hypotension prone stable patients.

BACKGROUND: It is now possible to link relative blood volume (RBV) measurements to a software loop designed to actuate a biofeedback response. This allows changes in RBV to determine constant alterations in both ultrafiltration rate and dialysate conductivity. RBV, plasma sodium and weight loss are driven throughout the treatment to achieve the best compromise. This system has been demonstrated to markedly reduce intradialytic hypotension in unstable patients. We have applied this treatment to stable, non-hypotension prone HD patients and report on the short-term outcomes. METHODS: We prospectively studied all 15 patients in a dedicated 4-station minimal care treatment area. Patients were studied for 3 weeks of standard HD, to understand the morphology and response to RBV in that individual. BF-HD was then instituted for a similar period (after a 2-week optimization period). Dialysis adequacy was assessed with equilibrated Kt/V measurements and urea mass removed in spent dialysate. RESULTS: We studied 263 treatment sessions. There was a reduction in symptomatic episodes (per patient over 3 weeks) from 3 +/- 0.5 (0-9) to 0.13 +/- 0.13 (0-2) with BF-HD, p < 0.001. Reductions in systolic BP > 40% fell from 1.4 +/- 0.4 (0-4) to 0.46 +/- 0.16 (0-2). Episodes of RBV falling > 10% fell from 6.3 +/- 0.85 (1-13) to 1.13 +/- 0.27 (0-4) with BF-HD, p < 0.001. Interdialytic weight gains fell from 2.08 +/- 0.05 (0.35-3.8) kg to 1.82 +/- 0.06 (0-3.7) kg, p = 0.009. Equilibrated Kt/V increased from 1.01 +/- 0.03 (0.61-1.35) to 1.13 +/- 0.03 (0.7-1.5), p = 0.01, and mass removed of urea increased from 24.9 +/- 3 (12.8-45) g to 32.7 +/- 1.9 (17.3-48.5) g. CONCLUSIONS: This is the first report of BF-HD increasing tolerability, reducing interdialytic fluid gains and enhancing urea clearance in non-hypotension prone chronic HD patients. These data suggest that the previously reported associated benefits of BF-HD may be applicable to the majority of HD patients.

Adult↗
PubMed2002

Simultaneous non-surgical removal and insertion of peritoneal dialysis catheters for defective drainage: a bedside, day case technique.

BACKGROUND: Outflow failure of peritoneal dialysis catheters is a commonly encountered problem. It may be possible to reposition the catheter by a variety of means, but this can be problematical and has variable long-term success. Commonly surgical catheter exchange is utilized, entailing inconvenience, expense and often, a reliance on temporary hemodialysis. We describe a technique allowing exchange of poorly functioning catheters with a relatively simple outpatient/day case percutaneous technique, allowing the continuation of peritoneal dialysis. METHODS: We report percutaneous exchange of 25 peritoneal dialysis catheters in 21 patients. The exchanges were performed under local anesthesia with a degree of sedation (if required). It involved the dissection down the distal cuff of the catheter and mobilization of the catheter below it. This was followed by division of the catheter, allowing passage of a guide wire into the peritoneal cavity and insertion of a further peel away sheath and insertion of a new catheter. The new catheter was tunneled out of the existing exit site after removal of the extraperitoneal portion of the old catheter by traction. RESULTS: Outflow failure was associated with fecal loading and malposition of the catheter in 14 out of the 21 patients. Exchange of catheter was successful in all the patients with good pelvic positioning of the replacement catheter in all but 1 of the cases. The mean period until the reinstitution of peritoneal dialysis was 5.1 days (range 0-14 days). Temporary hemodialysis was not required for any of the patients. One patient exhibited a small leak of peritoneal dialysis fluid after insertion, but this had spontaneously resolved within 6 days. Protracted satisfactory function of the peritoneal dialysis catheters was obtained in all but 1 of the patients (mean follow-up 51 weeks, range 11-73 weeks). CONCLUSIONS: We conclude that exchange of peritoneal dialysis catheters for problems with dialysate drainage, utilizing a non-invasive percutaneous technique is both effective and safe.

Adult↗
PubMed2002

Characterization of treatment dose delivered by albumin dialysis in the treatment of acute renal failure associated with severe hepatic dysfunction.

BACKGROUND: Acute liver cell failure (ALCF) commonly results in death and when complicated by acute renal failure (ARF), the mortality approaches 90%. Albumin dialysis allows partial replacement of some of the liver's excretory functions. The molecular absorbents recirculating system (MARS) has been recently introduced to provide this therapy. Thus allowing bridging to transplantation or hepatic regeneration. We have attempted to define the degree of "uremic" dialysis that this system can deliver as well as characterizing the dose of "hepatic" treatment, using a similar approach to solute remove as applied to assessing hemodialysis adequacy. As a secondary issue we also report on the clinical outcomes of this group of patients. METHOD: We treated 7 patients with ALCF and acute renal failure (6 of the patients having a formal diagnosis of hepatorenal syndrome), aiming to deliver a 5 treatment consecutive course consisting of 8 hours of albumin dialysis using the MARS monitor, combined with hemodialysis. Clinical and biochemical outcomes were assessed, and dialysis adequacy measured using urea reduction ratios, calculated Kt/V and measured Kt/V (using ionic dialysance). Treatment dose, with respect to the highly protein bound and lipophilic toxins that accumulate in hepatic failure, was assessed by calculating the bilirubin reduction ratio and percentage reduction in plasma ammonia and total bile acids. RESULTS: All of the patients had a degree of biochemical improvement with albumin dialysis. Urine output increased and the degree of encephalopathy improved. Mean bilirubin fell from 612 +/- 105.5 micromol/l (range 165.6 - 1,024 micromol/l) to 370.4 +/- 49.7 micromol/l (range 190.4 - 569.2 micromol/l), ALT reduced from 3,280 +/- 2,266 IU/l (range 40 - 18,876) to 639 +/- 230 IU/l (range 33 - 1677). Hepatic synthetic function improved with INR falling from 4.1 +/- 0.5 (range 2.1 - 6.4) to 2.8 +/- 0.6 (range 1.4 - 5.5). Plasma ammonia was reduced, falling from 162.4 +/- 15.4 (range 131.1 - 191.9 micromol/l) to 73.1 +/- 15 micromol/l (range 45.6 - 106.4 micromol/l). Bile acid levels fell from 132 +/- 10.2 micromol/l (range 110.7 - 155.8 micromol/l) to 36.9 +/- 6.1 micromol/l (range 24.6 49.6 micromol/l). The mean urea reduction ratio (URR) was 58.4 +/- 3.2% (range 39 - 76%). Mean Kt/V as assessed by ionic dialysance was 1.7 +/- 0.01 (range 0.8-2.4). Mean bilirubin reduction ratio (BRR) was 28.6 +/- 1.4% (range 12.5 - 39%). BRR was proportional to both URR and Kt/V. BRR was also proportional to the percentage reduction of ammonia and bile acid levels. Three of the 7 patients survived to be discharged from hospital and 4 died. CONCLUSION: Albumin dialysis appears capable of improving the outcome in patients with ALCF and hepatorenal syndrome. Eight-hour intermittent treatments with the MARS system in combination with hemodialysis deliver an adequate dose of dialysis with respect to urea. BRR may be an appropriate tool to allow further quantitative and comparative study of this technique.

Acute Kidney Injury↗
PubMed2002

Long-term use of 1.1% amino acid dialysis solution in hypoalbuminemic continuous ambulatory peritoneal dialysis patients.

INTRODUCTION: Malnutrition is a common problem in patients treated with continuous ambulatory peritoneal dialysis (CAPD). Hypoalbuminemia in CAPD patients is an independent risk factor for death and is associated with malnutrition. Previous short-term studies have examined the use of amino acid based PD solutions in terms of albumin levels and anthropometric changes, but not clinical outcome. We report on the extended use of 1.1% amino acid based peritoneal dialysis solution (Nutrineal) and have assessed clinical utility in terms of nutrition, biochemical indices, dialysis adequacy and clinical outcomes. METHODS: The effect of Nutrineal was studied retrospectively in 22 patients during the past 30 months. All patients had an albumin level of < 35 g/l prior to commencing Nutrineal, and had either a protein intake < 1.2 g/kg or weight loss of > 5% in the previous 3 months. 19 of the 22 patients underwent an 8-week trial of oral nutritional supplements with no improvement in serum albumin level. Albumin level, normalized protein catabolic rate, weight, Kt/V and creatinine clearance were assessed for all patients prior to Nutrineal and at the end of the study period. RESULTS: The mean time on Nutrineal therapy was 13.6 months (range 6-26 months). There were no reported side effects of the treatment. There was an average of 1 episode of peritonitis per 23 treatment months, and only 1 patient died (4% annually adjusted mortality cf 8.9% on the peritoneal dialysis program as a whole). There was a significant increase in albumin level from 22.45 +/- 0.97 range 14-33 g/l to 25.68 +/- 1.159 range 16-35 g/l (p = 0.0036). Normalized protein catabolic rate increased significantly, from 0.898 +/- 0.053 to 1.085 +/- 0.056 g/kg/day (p = 0.0057). Weight decreased slightly although this did not reach statistical significance. Kt/V and creatinine clearance both decreased significantly, but remained within the adequate range in > 80% of the patients. There was no significant change in residual renal function (mean residual creatinine clearance 3.8 +/- 0.59 ml/min at the start of the study period, cf 3.4 +/- 0.61 ml/min at the end). CONCLUSION: These data suggest that Nutrineal can be used safely and effectively for an extended period of time. Such use is associated with a low mortality rate and a low peritonitis rate, although dialysis adequacy is compromised to a degree.

Amino Acids↗
PubMed2001

Steroid and cyclophosphamide therapy for IgA nephropathy associated with crescenteric change: an effective treatment.

BACKGROUND: IgA nephropathy is the most common form of idiopathic glomerulonephritis. There is no current consensus on treatment for this condition. We report on the effect of immunosuppression with corticosteroids and cyclophosphamide for the treatment of IgA nephropathy associated with crescenteric change. METHODS: The effect of oral prednisolone (0.8 mg/kg initially, reducing to 0.4 mg/kg after 4 weeks) and cyclophosphamide (1.5 mg/kg) given until a plateau of response was obtained was studied in 9 patients with IgA nephropathy associated with severe inflammatory change and crescents. The initial diagnostic renal biopsies of these patients revealed 25-70% of the glomeruli effected with active cellular crescents. When response to therapy, plateaued cyclophosphamide was discontinued and prednisolone reduced from 0.4 mg/kg. Follow-up renal biopsy was performed in 8 of the 9 patients. Patients were maintained on prednisolone (5- 7.5 mg) and azathioprine (1 mg/kg) for further 2 years. RESULTS: The mean time until discontinuation of cyclophosphamide was 17.8 weeks (+/-1.23, range 12-25 weeks). There were no serious complications of therapy. There was an improvement in renal function in all patients with serum creatinine falling from a mean of 149.6+/-16.5, range 81-227 micromol/l to 116.4+/-8.6, range 80-158 micromol/l, p=0.01. Creatinine clearance improved from a mean of 57.1+/-9.9, range 21-104 ml/min to 87.2+/-10.1, range 39-125 ml/min, p=0.004. 24-hour urinary total protein fell over the same time m period from a mean of 4.54+/-1.1, range 1.0-11.27 g to 1.2+/-0.27, range 0.01-2.65 g, p=0.004. There were no significant differences in blood pressure during this time. Repeat renal biopsies showed significant degrees of histological improvement with healing of crescents and a reduction in acute inflammatory change in all except one patient. The mean period of follow-up after cessation of cyclophosphamide was 17.4+/-2.8 months, range 10-36 months. There was no significant change over this period in serum creatinine, creatinine clearance or urinary protein losses. CONCLUSION: These data suggest that IgA nephropathy associated with severe inflammatory and crescenteric change can be effectively and safely treated with a low-cost regime based on oral corticosteroids and cyclophosphamide tailored to a plateau of treatment response in individual patients.

Administration, Oral↗
PubMed1999

Effects of new analogues of vitamin D on bone cells: implications for treatment of uremic bone disease.

BACKGROUND: The use of calcitriol in the treatment of uremic hyperparathyroidism and renal osteodystrophy is limited in many patients by hypercalcemic side-effects. New less calcemic analogues of calcitriol are being developed, and some are under clinical evaluation. To investigate whether these compounds possess important differences in their action on bone cells, we have studied their effects [with and without parathyroid hormone (PTH)] on the release and synthesis of the resorptive osteotropic cytokine, interleukin-6 (IL-6). METHODS: MG 63 and SaOS-2 human osteoblastic cell lines were cultured for 6 or 24 hours in media containing calcitriol, the sterols of interest, or 1-34 synthetic PTH. IL-6 release was assayed by commercially available enzyme-linked immunosorbent assay. IL-6 mRNA levels were assessed by reverse transcriptase-polymerase chain reaction. RESULTS: We found that calcitriol and paricalcitol behaved in a similar fashion, resulting in increased IL-6 release only at higher concentrations (10(-7) to 10(-9) M). In contrast, 22-oxacalcitriol and 1,25-dihydroxydihydrotachysterol2 stimulated release to a similar extent but at concentrations three to four orders of magnitude lower (10(-11) to 10(-13) M), despite being less potent as suppressers of parathyroid function than calcitriol. Studies of IL-6 mRNA showed a similar pattern of concentration and cell line-dependent transcription. CONCLUSIONS: Compounds stimulating IL-6 release at concentrations achievable during the treatment of uremic hyperparathyroidism might favor continuing linked bone formation and resorption and thereby avoid adynamic bone disease while still allowing profound suppression of PTH.

Bone Diseases↗
PubMed1995

Prostate-specific antigen levels in patients receiving long-term dialysis.

OBJECTIVE: To investigate the effect, if any, of renal failure upon prostate-specific antigen (PSA) levels and the validity of PSA estimation as a marker of prostatic disease in renal failure. PATIENTS AND METHODS: PSA was measured in 65 men (median age 67 years, range 39-84) on regular haemodialysis and 37 men (median age 70 years, range 42-77) on continuous ambulatory peritoneal dialysis (CAPD). Patients with a PSA level > 4 ng/mL underwent prostatic biopsy guided by transrectal ultrasonography. RESULTS: There was no evidence of an artefactual elevation of PSA attributable solely to renal failure. All eight patients with a PSA level > 4 ng/mL had prostatic disease. CONCLUSION: PSA measurements in patients with end-stage renal failure treated by dialysis remain a useful marker of prostatic disease.

Adult↗
PubMed1992

Affect, personality, and social activity.

These studies examined relations between social activity and state and trait measures of Positive and Negative Affect. In Study 1 Ss completed scales relevant to 3-factor models of personality and a weekly mood and social activity questionnaire for 13 weeks. In Study 2 Ss completed measures of the 5-factor model of personality and a daily mood and social activity survey for 6-7 weeks. In within- and between-Ss analyses, socializing correlated significantly with state measures of Positive Affect and with trait measures of Extraversion/Positive Emotionality. These relations were relatively general across various types of positive affect and social events; however, specific types of social events also were differentially related to affect. In contrast, social activity had no consistent association with measures of Negative Affect or the other personality dimensions. The results support a temperamental view of Extraversion.

Adult↗
PubMed1989

Visual and auditory coding confusability in students with and without learning disabilities.

The nature of visual and auditory coding processes in students with learning disabilities (SLDs) and student controls (SCs) was examined with a letter-matching task on four types of successively presented letter pairs: identical (A,A), visually confusable (P,R), auditorily confusable (F,S), and neither visually nor auditorily confusable (N,T). Two delay intervals (0 and 2 seconds) were used between the presentation of the first and second letters. Analysis of decision latencies on the nonidentical letter pair trials revealed that with initial exposure to the task, the SLDs responded more slowly than SCs, but their general confusability patterns (visual and auditory) were similar. With additional practice, overall decision latencies were comparable for the two groups, while confusability differences emerged: SCs showed maximal visual confusability at a 0-second delay and maximal auditory confusability at a 2-second delay, while SLDs did not. Evidently, SLDs make less extensive use of visual and auditory coding processes compared to SCs.

Attention↗
PubMed1986

Birth order effects in second-generation alcoholics.

The effects of birth-order position (first-, middle- and last-born) in intact families with three children on the psychopathology scores of second-generation alcoholics were examined by administering the MMPI to 90 alcoholic sons of alcoholic parents. Analyses of variance (ANOVAs) applied to the individual MMPI scale scores revealed a consistent pattern of results: first borns evidenced significantly less exaggerated psychopathology scores than both groups of later borns. Most of the extreme scale scores obtained within this population of alcoholics were obtained from the later borns. Implications for previous generalizations about the alcoholic children of alcoholic parents are discussed.

Adult↗
PubMed1985

Neuroleptic malignant syndrome.

The neuroleptic malignant syndrome (NMS) is a potentially fatal complication of antipsychotic drugs. It is characterized by severe muscular rigidity, hyperthermia, and autonomic disturbances. Neuroleptic malignant syndrome is easily confused with other health problems; distinctions between it and malignant hyperthermia, heatstroke, and lethal catatonia are made. The relevant literature is reviewed; a case history is presented; and implications for nursing care (e.g., early detection) are discussed.

Adult↗
PubMed1983

Information processed from brief visual displays by learning-disabled boys.

The spans of apprehension of learning-disabled and normal boys were compared by means of a forced-choice letter-recognition task involving tachistoscopic exposures of letter displays. This task provides an estimate of the span that is relatively insensitive to memory or motivational influences. In Experiment 1, the spans of learning-disabled and normal boys were compared under 4 information conditions: with no noise letters present or with 2, 4, or 8 noise letters present. Experiments 2-4 examined 3 possible interpretations of the deficit in the span of apprehension observed for learning-disabled boys in Experiment 1. In Experiment 2, the possibility that the noise letters were more distracting for learning-disabled boys was examined by varying the amount of physical similarity and redundancy between the signal and noise letters. In Experiment 3, the possibility that the visual afterimage of the letter displays faded more rapidly for the learning-disabled boys was examined. In Experiment 4, the possibility that the learning-disabled boys were slower to pick up information from the decaying afterimages was examined. The results of these three experiments indicated that the decreased spans of apprehension observed for the learning-disabled boys in Experiment 1 resulted either from greater distractiveness or from the slower pickup of information, or both. The implications for visual training are discussed.

Attention↗
PubMed1978

Span of apprehension in hyperactive boys.

The spans of apprehension of hyperactive and normal boys were compared with a forced-choice letter-recognition task developed by Estes (1965). This task provides an estimate of the span which is relatively insensitive to either memory or motivational influences. The span size was the same for both groups when visual "noise" was absent. In the presence of noise, span size for the hyperactive boys decrease. Moreover, as the number of noise letters increased, the reduction in span size observed for the hyperactive boys increased. It is argued that this increasing reduction in span size represents a true deficit in attention.

Afterimage↗
PubMed1978

Effect of noise distractibility on the spans of apprehension of hyperactive boys.

Denton and McIntyre (1978), using a forced-choice letter-recognition procedure, demonstrated increasing reductions in the spans of apprehension of hyperactive as compared to normal boys when a signal letter was embedded within an increasing number of noise letters. In the present study, the effect of variations in the amount of physical signal-noise similarity and noise redundancy upon the spans of apprehension of hyperactive and normal boys was compared to determine whether noise letters act as more potent distractors for the hyperactive boys. Results indicated the spans of both groups were effected equivalently by variations in signal-noise similarity and noise redundancy. No evidence for a distractibility explanation was obtained.

Attention↗