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Biomedical subjects

N K Man

Publications and source records attributed to N K Man.

At least 109 records · Page 6Linked to original sources
PubMed1980

[Evaluation of hemodialysis systems (author's transl)].

Since March 1973, approval procedure for hemodialysis systems devices is mandatory in France. Basically it controls the minimum requirements to insure the effective, safe performance of these devices in the treatment of end stage renal disease. They include dialysing fluid systems, monitoring equipment and dialyzers. We have controlled 28 dialysate delivery system monitors and 21 dialyzer models. During the approval procedure a high rate of cases which do not meet the minimal requirements, were observed: 61 p. cent for the identification of the device, 72 p. cent for the safe electrical current limits (French National Standard), 83 p. cent for the monitoring and 22 p. cent for the duration (1,000 hours for center utilisation, 1,500 hours for home utilisation). Better results were found with dialyzer performances. Ultrafiltration flow rate and solute dialysance measured in vitro under clinical conditions of flow rates and pressures correlated well with the values claimed by the manufacturers. Problems encountered during the approval procedure stemmed from the lack of National and International Standard for hemodialysis systems and the poor compliance of the manufacturers to "good manufacturing practice" rules.

Clinical Trials as Topic↗
PubMed1980

Improvement of post-heparin lipolytic activity (PHLA) after haemofiltration, in uraemic patients.

UNLABELLED: The decrease of serum PHLA in uraemic patients has been attributed to toxic effects of 'middle molecules' on lipoprotein lipase. Haemofiltration could improve PHLA by increasing 'middle molecule' clearance. Serum triglyceride concentration decreased and PHLA improved in three uraemic patients who received haemofiltration during three weeks as the initial treatment schedule. Activated PHLA of a healthy subject failed to be inhibited by uraemic sera and uraemic plasma ultrafiltrates obtained in vitro using polyacrylonitrile and cuprophane membranes. CONCLUSION: haemofiltration is able to improve PHLA and to restore normal serum triglyceride concentrations. The reported toxicity of uraemic serum may affect metabolic steps preceding the activation of the circulating lipolytic enzymes.

Blood↗
PubMed1979

Plasma inhibitors of the erythrocyte hexose monophosphate shunt in uraemia.

Sulphaemoglobin production, induced by an oxidative stress (ascorbate and cyanide) has been studied in uraemic patients. Results are expressed as the ratio of optic density of sulphaemoglobin (620nm) to optic density of total haemoglobin (540nm). The mean (+/- SEM) ratio found was 0.35 +/- 0.03 in 28 controls and 0.56 +/- 0,03 in 51 uraemic subjects (p less than 0.001). Cross incubation tests demonstrated that the anomaly was caused by a plasma factor. In vitro studies - guanidinic compounds added to control erythrocyte suspensions before incubation - suggest that this factor might be guanidinic propionic acid.

Anemia, Hypochromic↗
PubMed1978

[Oxygen consumption and body weight development of chronic uremic rats (author's transl)].

Impaired weight gain, a common feature in experimental chronic uremia, led to compare oxygen consumtion values of chronic uremic rats and their controls. Oxygen consumption measurement may allow an approach to the evaluation of total energy requirement. Three groups of animals were considered: uremic rats (CU) of less weight (402.66 +/- 9.9 g) than their control group (NA) (498.3 +/- 26.13) and younger normal animals (NJ), showing a similar weight (376.0 +/- 8.8) to that of the uremics. Significant differences in oxygen consumption values/body weight were found between group NJ (0.927 +/- 0.042 ml O2/mn/100 g rat) and both groups CU and NA (0.788 +/- 0.036 and 0.788 +/- 0.028 respectively). Proportional decrease of energetically active body mass in chronic uremic animals may be the reason of the findings.

Animals↗
PubMed1978

Tolerance to high ultrafiltration rates during closed batch hemodialysis.

The tolerance to high levels of ultrafiltration that has been observed when using a RP-6 dialyzer with polyacrylonitrile membrane and a closed batch dialysate delivery system has led the authors to put patients on a free sodium and fluid intake. Eight patients were put on such a diet for six months. They have been dialyzed four to five hours, three times per week, on a RP-6-Rhodial 75. The mean intersession weight gain was 4.29+/-0.18 Kg after three days for a mean predialytic body weight of 63.55+/-2.54 Kg. Mean predialytic blood pressure was 1.38+/-4 mmHg for systolic pressure and 82+/-5 mmHg for diastolic pressure. Mean ultrafiltrate volume was 4.86+/-0.36 liters which corresponds to a sodium output of 661.3+/-49.5 mEq. Total plasma protein and hematocrit increased 18.8+/-3.34% and 19.13+/-3.22%, respectively, when the pre and post-dialytic values were compared. No clinical sign of fluid overload (dyspnea, edema, etc.) was noted in these patients. Cardiothoracic index remained in the normal range. This tolerance is due, possibly, to the high sodium concentration (145 mEq/L) in the dialysate. The free sodium and water diet may contribute to a better rehabilitation.

Adult↗
PubMed1978

Evaluation of plasma neurotoxin concentration in uraemic polyneuropathic patients.

Purification of b4-2 sub-peak obtained on DEAE Sephadex A25 chromatography gave us the possibility of quantifying the plasma concentration of the neurotoxin present in uraemic patients with active polyneuropathy. From the purified neurotoxin isolated by kieselguhr and cellulose chromatography we calibrated analytic columns for b4-2 analysis. Plasma concentration, measured in 6 uraemic neuropathic patients, is between 13 and 19 mg/litre. In 52 uraemic patients without neuropathy, the plasma concentration is between 3 and 9 mg/litre. In 20 healthy subjects the plasma concentration is less than 1 mg/litre. The weekly neurotoxin removal in uraemic patients without neuropathy, treated by a five hours RP6 session 3 times a week, is of the same order of magnitude as the weekly urinary excretion in healthy subjects. Preliminary results of a tentative identification of this purified product indicate that it is not a polypeptide but an acid-polyol with carbohydrate structure.

Chromatography, Ion Exchange↗
PubMed1978

Anemia and secondary hyperparathyroidism.

Anemia has been recognized recently as a possible complication of primary hyperparathyroidism. If the hyperparathyroid state can induce anemia in patients with normal kidney function, the extremely high levels of circulating parathyroid hormone usually observed in hyperparathyroidism secondary to chronic renal failure may have an unfavorable influence on the anemia of uremic patients. We investigated the influence of subtotal parathyroidectomy on the severity of the anemia of 18 uremic subjects undergoing long-term hemodialysis therapy. Subtotal parathyroidectomy resulted in a significant increase of mean hematocrit value. RBC count, and hemoglobin level. Serial bone biopsies suggested a relationship between the amount of marrow fibrosis and the improvement of anemia after surgery, but the precise mechanism of this phenomenon is still unknown.

Adult↗
PubMed1977

Structural study of circulating thymic factor: a peptide isolated from pig serum. I. Isolation and purification.

A circulating thymic factor (FTS) has been characterized by a bioassay based on its ability to render theta-negative rosette-forming cells theta-positive and azathioprine-sensitive. FTS was sequentially purified and finally isolated from 1000 liters of pig serum by ultrafiltration, gel filtration, and ion exchange chromatography. Its amino acid composition and apparent molecular weight estimated by Sephadex G-25 chromatography, indicate that FTS is a nonapeptide of composition lysine, aspartic acid (or asparagine), serine 2, glutamic acid (or glutamine) 2, glycine 2, and alanine.

Amino Acids↗
PubMed1977

Effects of high dialysate calcium concentration on bone remodelling, serum biochemistry, and parathyroid hormone in patients with renal osteodystrophy.

The influence of a dialysate calcium concentration of 8.0 mg/100 ml (treatment period 2) vs. 7.0 mg/100 ml (treatment period 1) on plasma calcium, phosphorus, serum immunoreactive parathyroid hormone (iPTH), bone histology, intestinal calcium absorption, and calcium transfer across the dialysis membrane was investigated in six patients with renal osteodystrophy undergoing intermittent hemodialysis. During the periods 1 and 2, the plasma calcium changes before and after dialysis were not significantly different. A significant increase in mean postdialysis plasma calcium level was observed during both periods when compared to mean predialysis level. A significant, inverse relation was found between predialysis plasma calcium and the increase in plasma calcium during hemodialysis runs. Calcium transfer across the dialysis membrane and fractional intestinal absorption of calcium in the postdialysis state were determined in four out of the six patients. During period 2, calcium transfer was higher in all four patients but intestinal calcium absorption was moderately higher only in one and strikingly lower in the remaining three patients when compared to period 1. Although brought up to 8.0 mg/100 ml, this higher dialysate calcium significantly decreased the level of serum iPTH only in one out of the six patients; in this patient, osteoclast count, active resorption surface, and periosteocytic osteolysis decreased. In a second patient, although the level of serum iPTH seemed to decrease markedly osteoclastic and osteocytic resorption did not change. In the remaining four patients, the level of serum iPTH was unchanged and bone resorption parameters were found unchanged or aggravated. It is concluded that providing additional calcium (using a dialysate calcium concentration of 8.0 mg/100 ml), the goal of which was to decrease secondary hyperparathyroidism, proved to be successful only in one patient and failed to do so in the five others. Secondary hyperparathyroidism was even found aggravated in three of them. Thus, the use of a dialysate calcium concentration of 8.0 mg/100 ml did not result in any advantage over that of 7.0 mg/100 ml in five out of six patients studied.

Adult↗