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Biomedical subjects

A L Babb

Publications and source records attributed to A L Babb.

At least 37 records · Page 2Linked to original sources
PubMed1979

Effect of residual renal function on minimum dialysis requirements.

In two groups of haemodialysis patients, the effect of residual renal function (RRF) on motor nerve conduction velocity (MNCV) was prospectively studied. Patients belonging to Group I had stable GFR of greater than 1 ml/min while Group II patients had gradually declining GFR. As a result, the dialysis index for middle molecules, DI(MM), remained above 1.0 in Group I despite dialysis schedules as short as 6 hr/wk. DI(MM) in Group II fell gradually below 1.0 as renal function deteriorated on equally short dialysis schedules. None of the five patients in Group I developed neuropathy during 1.2-4.1 years of reduced dialysis. However, all four patients belonging to Group II developed significant (p less than .01) slowing of MNCV when their GFR declined below 0.5 ml/min. Neuropathy in this group was arrested or reversed by increasing DI(MM). It is, therefore, proposed that residual renal function is a major determinant of dialysis requirements.

Glomerular Filtration Rate↗
PubMed1978

Uremic neuropathy: evidence of middle molecule toxicity.

Ten dialysis patients were followed in a prospective study to determine the neurotoxicity of metabolites in the middle molecule (MM) molecular weight (mol wt) range of 500-200 daltons/molecule. In the absence of readily available direct serum measurements of MM concentrations, a theoretically calculated dialysis index, D1(MM), which included the combined effects of dialysis and residual glomerular filtration rate (GFR) on MM removal was used to estimate changes in their predialysis concentrations. The ten patients were dialyzed on protocols which yielded a D1(MM) less than 1.0. Evidence of uremic neuropathy developed in six of these ten patients, and five of these six also developed a progression in their anemia. Two additional patients with no signs of neuropathy developed a progression in their anemia. One patient developed pericarditis with tamponade. A total of eight patients developed complications. One additional patient developed increased weakness, tiredness and general malaise without change in objective findings. When the dialysis therapy to reduce MM concentrations by increasing the D1(MM) above 1.0 was instituted, the complications were reversed. Our data support the findings of others, namely, that there are toxic substances in the MM mol wt range of 500-2000 daltons/molecule. However, a synergism between elevated concentrations of small molecules and MM cannot be ruled out.

Blood Urea Nitrogen↗
PubMed1978

Less dialysis-induced morbidity and vascular instability with bicarbonate in dialysate.

We devised three protocols to test the postulate that increased morbidity during high-efficiency dialysis with large-surface-area units (LS) might be due in part to the increased flux of bicarbonate out and acetate into the patient inherent is LS dialysis. The first protocol showed that with LS-acetate dialysis there was a marked fall in plasma bicarbonate and Pco2 during the first 3 to 4 h, followed by a rapid rise in bicarbonate above normal and return to control in Pco2. With LS-bicarbonate dialysis, these oscillations were largely eliminated. A second double-blind protocol showed that central nervous system-type symptoms noted during and after LS-acetate dialysis were reduced significantly by switching to LS-bicarbonate dialysis. The third protocol showed that with LS-carbonate the tolerable rate of ultrafiltration could be increased 67% compared with LS-acetate dialysis.

Acetates↗
PubMed1978

Carbamylation distributions in extracorporeal treatment of sickle cell anemia.

The extracorporeal exposure of blood from patients with sickle cell anemia results in the binding of different amounts of cyanate to the hemoglobin of individual erythrocytes. This distribution pattern of carbamylated hemoglobin may affect the efficacy of treatment. A computer model has been developed to predict the carbamylation distribution attained in batch ex vivo exposures. In addition, an autoradiographic technique has been developed whereby the actual distribution pattern of carbamylated hemoglobin in small volumes of blood can be determined. Agreement was demonstrated between the computer model predictions and the actual distribution patterns. The model was applied to published results of extracorporeal treatments of sickle cell patients, and profiles of loading were compared. With the use of such approaches it will be possible to test the importance of the erythrocyte distribution of carbamylated hemoglobin on clinical effects and to design protocols to achieve an optimum distribution. The procedure may be adapted to the distribution of other therapeutic agents as they become available.

Anemia, Sickle Cell↗
PubMed1977

Kinetics of the cyanate-hemoglobin reaction in whole blood.

The kinetics of the cyanate-hemoglobin reaction in normal whole blood have been investigated. The mechanism was found to be second order, irreversible, bimolecular. The influence of the temperature, pH, Po2, and Pco2 on the reaction rate constant was examined. A temperature change from 37 degrees to 42 degrees C, resulted in a 50 percent increase in the rate constant. The rate constant increased in proportion to the pH decrease, and deoxygenated whole blood was carbamylated approximately twice as fast as oxygenated blood. Carbon dioxide pressures had no influence on rates of carbamylation when a constant pH was maintained. A maximum rate constant of 3.7 M-U min.-u was obtained with conditions which were compatible with the red blood cells. This knowledge of the reaction mechanism and the influence of important system parameters on the reaction rate constant may be applied to the development of an extracorporeal system for the treatment of sickle cell anemia.

Carbon Dioxide↗
PubMed1976

Whole blood trace element concentrations during total parenteral nutrition.

Samples of whole blood in eight patients on long-term total parenteral nutrition (TPN) and in four who served as controls were analyzed for trace element concentrations of Au, Br, Cu, Mn, Cr, Sb, Fe, Zn, Co, Hg, Rb, and Se. The concentrations of essential elements in the patients deviated significantly from those in the control group. The Mn concentration in blood was consistently higher in patients, owing to the high Mn concentration in the nutrient solutions. A reciprocal relationship between Cu and Zn was demonstrated in one patient. Some trace element concentrations are correlated with the duration of malabsorption and the amount of oral intake during TPN. This study shows that patients on TPN may have abnormal trace element profiles and that TPN currently does not supply the necessary concentrations of trace elements.

Adolescent↗