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Biomedical subjects

J Jamart

Publications and source records attributed to J Jamart.

At least 163 records · Page 9Linked to original sources
PubMed1992

Statistical tests in medical research.

Various propositions have been made to improve the statistical quality of medical journals: using statistical referees, promoting better collaboration between statisticians and researchers, and teaching of basic statistics to clinicians. The most frequent errors found in medical articles are misinterpretation of p-values or non-significant results and confusion between statistical and clinical significance, inappropriate use of tests requiring precise assumptions, inappropriate or not controlled multiple testing and particularly testing of post hoc hypotheses, and overemphasis on p-values. Many errors arising from the misinterpretation of results of statistical hypothesis tests, the basic principles of this methodology are emphasized, and the usual fallacies found in the medical literature are reviewed.

Research↗
PubMed1992

Does flow character of cardiopulmonary bypass make a difference?

The influence of pulsatile bypass flow on the performance of the cardiovascular system, fluids and blood balance, acid-base equilibrium, and splanchnic function was investigated. One hundred patients scheduled for elective coronary artery bypass grafting were randomly divided into a group of standard perfusion (NP) and a group of pulsatile perfusion (PP). At the end of the operation, similar cardiac performance developed in both groups that was higher than before bypass: left ventricular stroke work index after bypass, 56.8 +/- 2.7 gm/beat per square meter in the NP group and 56.7 +/- 2.6 gm/beat per square meter in the PP group (not significant). Further determinations did not differ among the groups. After discontinuation of cardiopulmonary bypass, bypass grafts flow measured using an electromagnetic probe did not differ among the groups. During the postbypass period, mean arterial pressure and systemic vascular resistance were similar (mean arterial pressure 86.8 +/- 1.6 mm Hg in the NP group and 88.5 +/- 1.7 in the PP group; systemic vascular resistance 817 +/- 33 dyne.sec/cm5 in the NP group and 881 +/- 34.5 in the PP group), as were further determinations. However, severe hypotension requiring the administration of vasoconstrictors was observed more frequently in PP group of patients (20 versus 6%; p < 0.05). Fluid balance determined at the second postoperative day was similar among the groups (+1307 +/- 239 ml in the NP group and +1535 +/- 266 ml in the PP group). Blood loss was 1122 +/- 120 ml in the NP group and 1263 +/- 119 ml in the PP group during the first postoperative day (p = 0.407). Urine output during bypass was lower in the PP group (261 +/- 25 versus 341 +/- 26 ml/hr; p = 0.028). The creatinine clearance was 96.4 +/- 10.3 ml/min in the NP group and 92.6 +/- 7.0 ml/min in the PP group (not significant); amylase and lipase clearance did not differ among the groups. Finally, no significant difference was detected in arterial lactic acid determinations and acid-base balance assessment between the groups postoperatively. Thus equivalent cardiovascular hemodynamics, a good control of fluids and blood balance, acid-base equilibrium, and a satisfactory protection of the function of kidneys and pancreas were obtained with both types of perfusion.

Cardiopulmonary Bypass↗
PubMed1992

Regenerative nodules in hepatic cirrhosis. Value of gradient-echo MR imaging with a surface coil.

To evaluate the accuracy of surface coil gradient-echo (GRE) imaging in the detection of regenerative nodules of hepatic cirrhosis, 53 patients with diffuse liver disease, among whom 31 had cirrhosis, were prospectively investigated. Three GRE sequences acquired with a surface coil were used in the study: a T2*-weighted, a T1-weighted, and a gadopentetate-enhanced sequence. ROC analysis showed that two surface coil GRE sequences were superior to conventional T2-weighted spin-echo imaging acquired with a body coil for the detection of regenerative nodules. The detection of regenerative nodules was also more accurate for the diagnosis of cirrhosis than the measurement of the caudate-to-right lobe ratio. These results suggest that there could be a potential for surface coil GRE imaging in the assessment of the characteristic macroscopic alterations of cirrhosis.

Adult↗
PubMed1991

Effect of dialysis membrane and patient's age on signs of dialysis-related amyloidosis. The Working Party on Dialysis Amyloidosis.

This 12 center study was designed to assess factors affecting the development and progression of beta 2-microglobulin amyloidosis in long-term dialysis. A total of 221 patients who were on hemodialysis for more than five years, and who were treated the entire time only with AN69, a biocompatible, highly permeable membrane, or cuprophane, a less permeable, poorly biocompatible membrane (Cell) were evaluated for time on dialysis, development of carpal tunnel syndrome, and cystic bone lesions. X-ray documentation was taken in a minimum of four of the six following joints: both hips, wrists and shoulders. The data demonstrate that patients treated solely by AN69 membranes display signs of bone amyloidosis less frequently than do those treated by Cell membranes. Age at onset of dialysis was found to have a striking correlation with the development of carpal tunnel syndrome and bone amyloidosis, while no significant influence was found for hyperparathyroidism, sex or year of first dialysis.

Acrylic Resins↗
PubMed1990

Surgery in patients on long-term steroid therapy: a tentative model for risk assessment.

Increased morbidity after operation has been associated with long-term steroid therapy. To determine the correlation between steroid therapy and such morbidity, the perioperative course of 55 steroid-treated patients was reviewed: 27 had bronchopulmonary disorders (group P) and 28 had non-pulmonary diseases (group NP). There were six (11 per cent) deaths, of which three were steroid related. Among the 13 non-lethal postoperative complications, eight were considered to be steroid related in group P and one in group NP. The duration of steroid therapy was for a median of 24 months (range 1-408 months) in group P and for a median of 6 months (range 1-240 months) in group NP (P less than 0.01). In contrast, the daily dose of hydrocortisone or equivalent before operation was significantly lower in group P, with a median of 0.51 mg kg-1 day-1 (range 0.20-2.56 mg kg-1 day-1) than in group NP, with a median of 1.20 mg kg-1 day-1 (range 0.23-7.38 mg kg-1 day-1) (P less than 0.01). In conclusion, bronchopulmonary disorders requiring a long duration of steroid therapy are associated with a higher risk of steroid-related complications after surgery. A convenient mathematical model is proposed which may allow a preoperative assessment of surgical risk, using steroid dose and duration of treatment.

Adult↗
PubMed1990

Dynamic spin-echo imaging with Gd-DTPA: value in the differentiation of hepatic tumors.

Thirty patients with hemangiomas (n = 6), benign liver cell tumors (n = 7), and primary or metastatic malignant tumors of the liver (n = 17) underwent dynamic MR imaging with Gd-DTPA to determine the value of the procedure in the differentiation of hepatic tumors. The diagnoses were proved by histology or follow-up. Hemangiomas had a significantly greater mean T2 value (192.1 +/- 34.8 msec) than did both benign liver cell tumors (71.9 +/- 16.9 msec; p less than .01) and primary or metastatic malignant tumors (79.7 +/- 21.2 msec; p less than .01), but the T2 values of benign liver cell tumors and malignant tumors were not significantly different. Both hemangiomas and benign liver cell tumors had a significantly greater mean signal-intensity ratio (1.86 +/- 0.60 and 1.77 +/- 0.26, respectively) than did malignant tumors (1.04 +/- 0.34; p less than .01) in the early phase after Gd-DTPA administration, and hemangiomas had a significantly greater signal-intensity ratio (1.59 +/- 0.21) than did both benign liver cell tumors (1.21 +/- 0.08; p less than .01) and malignant tumors (1.06 +/- 0.26; p less than .01) in the delayed phase. These results suggest that dynamic MR images obtained after administration of Gd-DTPA are useful in differentiating hepatic hemangiomas, benign liver cell tumors, and malignant liver lesions.

Adenoma, Bile Duct↗
PubMed1990

Prediction of risk in noncardiac operations after cardiac operations.

To determine the preoperative variables affecting the mortality rate and the development of severe complications in patients who have had myocardial revascularization or a valve replacement and who then undergo a noncardiac operation, we retrospectively studied data from 120 such patients over the 5 years from 1982 through 1986. Thirty-six percent of patients had a noncardiac operation during the first month after the cardiac operation. The mortality rate was 11%, and the morbidity rate was 56%. The statistical comparison of the predictive accuracy of postoperative complications of three simple, widely used classifications (American Society of Anesthesiologists physical status, New York Heart Association classification, Massachusetts General Hospital cardiac risk index) demonstrated the superiority of the simplified three-class cardiac risk index (Massachusetts General Hospital-cardiac risk index; predictive accuracy of 84%). In a multivariate discriminant analysis of 21 variables in this population, five variables (myocardial infarction in previous 6 months, S3 gallop or jugular vein distention, arrhythmia on last preoperative electrocardiogram, emergency operation, delay between cardiac and noncardiac operation) were identified as being the most predictive of a postoperative complication. When these variables were used in the function (DF3) obtained by linear discriminant analysis, the prediction accuracy of a postoperative complication reached 83%. Performance of the new models in a prospective validation population remained satisfactory (75% for Massachusetts General Hospital-cardiac risk index three-class index and 72% for DF3). Extensive statistical analysis of our data tested by a validation study provided simple predictive models based on clinical variables easily available even in emergency situations.

Adult↗
PubMed1989

Evidence that atrial natriuretic factor is the humoral factor by which volume loading or mannitol infusion produces an improved renal function after acute ischemia. An experimental study in dogs.

This experimental study in dogs was designed to investigate whether maximal loading produces atrial natriuretic factor (ANF) release and whether this physiological peptide is involved in the improvement of the early renal function recovery after acute ischemia. The experimental protocol included a renal artery occlusion for 45 min in uninephrectomized dogs and the measurement of various parameters of renal function over 2-hr period after declamping. There were 3 experimental groups. In the control group (I) (n = 10), the dogs received, after ischemia, an isotonic saline solution infusion at a rate of 0.2 ml/kg/min. In group II, (n = 10) the animals underwent acute volemic expansion (1 ml/kg/min) with whole blood (hematocrit approximately equal to 25%) during the ischemic period, and after declamping, an isotonic saline infusion (NaCl 0.9%) infusion at the same rate as in the control group. In group III, (n = 8) the dogs only received NaCl 0.9% (0.2 ml/kg/min) before ischemia and alpha human ANF (3.6 ng/kg/min) dissolved in saline after ischemia and during the 2 hr of the renal recovery period. Volemic expansion induced a highly significant increase of the cardiac filling pressures concomitant with a prompt but transient 5-6-fold increase in ANF levels (357 +/- 92 pg/ml versus 60 +/- 4.1 pg/ml in controls at the time of declamping [P less than 0.05]). With these higher plasma ANF levels in overloaded animals, we observed, 2 hr after declamping, considerably improved renal function recovery in terms of glomerular filtration rate--37.5% +/- 8.7 versus 11.8 +/- 3.9%; urinary sodium excretion rate--53.89 mu eq/min versus 5.36 +/- 1.2 mu eq/min (P less than 0.01); total Na reabsorption rate--1.2 +/- 0.23 meq/min versus 0.28 +/- 0.09 meq/min (P less than 0.01) (group II vs. controls, respectively). A 1-28 alpha ANF infusion after the ischemic insult allowed a comparable but more significant improved recovery of renal function--indeed, 2 hr after declamping, the GFR reached 73.7 +/- 14% of the preoperative GFR values. The urinary sodium excretion rate was 15-fold higher than in controls, and the total and fractional sodium reabsorption rates followed a similar increase. These beneficial effects of ANF were obtained with low doses of synthetic ANF (3.6 ng/kg/min) inducing plasma levels slightly higher (120 pg/ml) than in controls and comparable to the levels reached in the overloading group. In addition, maximal loading or ANF infusion produces an inhibition of the aldosterone rise occurring after the ischemic insult.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Prevention of acute cyclosporine nephrotoxicity by atrial natriuretic factor after ischemia in the rat.

The present experimental study investigates whether the atrial natriuretic factor (ANF) is able to prevent the nephrotoxic effects of cyclosporine infused after 30 min of warm renal ischemia in the rat. At 2 hr after the end of ischemia, the glomerular filtration rate was improved by an ANF infusion: 390 +/- 19 microliters/min/100 g versus 298.3 +/- 31 microliters/min/100 g in ANF and saline-infused rats, respectively (P less than 0.05). Intravenous CsA infusion at a dose of 2.5 mg/kg/day produced a more pronounced fall in GFR when compared with the control: 205.4 +/- 19.7 microliters/min/100 g versus 298.3 +/- 31 microliters/min/100 g in CsA and saline, respectively (P less than 0.05). In contrast, a synthetic rat atriopeptin III (0.5 microgram/kg/min) infusion after ischemia given together with CsA prevented its deleterious effects upon GFR: 316 +/- 22 microliters/min/100 g versus 205.4 +/- 19 microliters/min/100 g in ANF/CsA versus CsA alone (P less than 0.001). Moreover, the natriuretic ANF effects remained unaffected by high plasma CsA peak levels: indeed, other parameters of renal function--urinary flow, urinary sodium concentration and excretion rates, and urinary sodium reabsorption and fractional excretion rates, were significantly increased in ANF alone or CsA/ANF groups. These preliminary results suggest that ANF may be useful in renal transplantation or in the management of patients given large doses of CsA (liver or heart transplant) since, despite nephrotoxic CsA levels (greater than 1500 ng/ml), ANF provides an improved GFR and tubular function after ischemia.

Acute Kidney Injury↗
PubMed1987

Tobacco and occupation as risk factors in bladder cancer: a case-control study in southern Belgium.

A pilot case-control study on bladder cancer, with population-based controls matched for each of 74 cases, has been conducted in two industrial areas of Southern Belgium in order to analyze the influence of tobacco use and occupation. Observed bladder cancer risk for smokers is more than 5 times higher than that for non-smokers, and the risk for people having an a priori hazardous occupation is about 3.5 times higher than that of other subjects. A dose-response relationship was found for tobacco exposure and duration of employment. It seems that the risk is increased in a log-linear way by these variables. Population attributable risks show that in 20 cases of bladder cancer, 17 could be explained by the two factors combined. This study also reveals an increased risk for metal workers, truck and engine drivers, coal-miners, and rubber and coal-tar workers. The risk for metal workers is specially high in the case of turners, metal fitters, blacksmiths, stokers and workers exposed to hot metal.

Adult↗
PubMed1983

Total colectomy with ileorectal anastomosis in surgical management of toxic megacolon.

Twenty-five patients with toxic megacolon are reported. The most frequent etiology of this syndrome was ulcerative colitis and the main complication colonic perforation. Toxic dilatation generally involved the transverse colon. Twenty patients were treated by a surgical procedure, namely two enterostomies and eighteen colectomies. A total colectomy with ileorectal anastomosis was performed in ten patients. Mortality for the whole series was 32%, but was reduced to 14% in the last 4 years. There were no deaths and no complications needing surgical management in the group of patients treated by total colectomy with ileorectal anastomosis. However, the method resulted in one failure. The satisfactory results obtained with this procedure must be emphasized. Despite the small number of so-treated patients reported in world literature, it is suggested that total colectomy with ileorectal anastomosis must be regarded as the procedure of choice for toxic megacolon without peritonitis.

Adolescent↗