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Biomedical subjects

D Rodbard

Publications and source records attributed to D Rodbard.

180 records · Page 10Linked to original sources
PubMed1970

Unified theory for gel electrophoresis and gel filtration.

Unified theory for gel electrophoresis and gel filtration: The behavior of macromolecules in gel filtration and gel electrophoresis may be predicted from Ogston's model for a random meshwork of fibers. This model has been generalized to apply to nonspherical molecules and to several gel types. The model provides equations for inter-relationships between mobility, partition coefficient, gel concentration, and molecular radius; it gives a non-Gaussian distribution of pore sizes as a function of gel concentration. The theory defines conditions for optimal separation and optimal resolution in gel filtration and gel electrophoresis. The difference in resolving power between the two fractionation methods is accounted for by the fact that gel filtration is a form of partition chromatography.

Chromatography, Gel↗
PubMedDate not supplied

Vasopressin receptors in human seminal vesicles: identification, pharmacologic characterization, and comparison with the vasopressin receptors present in the human kidney.

Because of the presence of a high density of vasopressin receptors in the epithelial cells of porcine seminal vesicles similar to the V2 vasopressin receptors of renal tubules, human seminal vesicles and kidney were investigated using quantitative binding and adenylate cyclase studies. Tissues were obtained at surgery from 17 patients with urologic diseases. A homogeneous class of vasopressin binding sites have been found in both seminal vesicles and renal medulla. However, the vasopressin receptors present in these tissues are different in terms of ligand specificity and adenylate cyclase activation. In seminal vesicles, the V1 vasopressin antagonist d(CH2)5 TyrMeAVP is 36-fold, more potent than the V2 agonist dVDAVP in displacing [3H]AVP binding, while in the medullopapillary portion of kidney dVDAVP is 24-fold, more selective than d(CH2)5 TyrMeAVP for the arginine vasopressin binding site. Furthermore, arginine vasopressin induces a dose-dependent increase in adenylate cyclase activity in renal membranes, while it was ineffective in seminal vesicle membranes. These results indicate that a very high affinity (0.2 nM), low capacity (14 fmoles/mg protein) class of vasopressin receptors is present in human seminal vesicles, having pharmacologic characteristics similar to the V1 subtype of vasopressin receptors. The presence of a high affinity (1.6 nM), high capacity (350 fmoles/mg protein) V2 subtype of vasopressin receptors in human renal membranes is also confirmed. The density of the vasopressin receptors present in human seminal vesicles is inversely correlated with patient age, consistent with a physiologic role for vasopressin in the regulation of accessory sex gland activity.

Adenylyl Cyclases↗
PubMedDate not supplied

EXPFIT: a program for simultaneous analysis of families of exponential decay curves.

We have developed a program to facilitate the simultaneous analysis and weighted least-squares curve fitting of families of exponential decay curves, subject to appropriate constraints. The simultaneous analysis of all curves allows one to pool information from several subjects or experiments, and avoids the need for approximations inherent in normalizing or transforming data. Selected parameters of the model can be constrained, i.e. shared among several curves, or set to a constant value. Hypotheses about the system under study can be tested in an objective, statistically valid manner. A BASIC computer program for routine data analysis is presented, with an example of its application to illustrative data.

Data Interpretation, Statistical↗
PubMedDate not supplied

Increased pulse wave velocity and shortened pulse wave transmission time in hypertension and aging.

We measured pulse wave velocity (PWV) and pulse transmission time (PTT) in 29 patients with hypertension, ranging in age from 37 to 73 years, in a series of 36 normal subjects with the same age range, and in an additional series of 44 normal subjects aged 18-35 years. PWV increases linearly with age for both normal subjects and patients with hypertension, with a corresponding significant decrease in PTT. There was a statistically highly significant (p < 0.001) increase in PWV in hypertension at all ages examined. The present simple noninvasive methods may be useful when evaluating risk factors for atherosclerosis and when evaluating response to therapeutic intervention.

Adolescent↗
PubMedDate not supplied

Ambulatory glucose profile: representation of verified self-monitored blood glucose data.

Sixty-nine individuals with diabetes (23 with type I, 15 with pregestational, and 31 with gestational) used specially modified reflectance meters containing memory chips enabling the instruments to store 440 individual blood glucose values with corresponding time and date. These data were organized into 14-day periods and then collapsed into a graphic depiction, the Ambulatory Glucose Profile (AGP), which was represented as the pattern of the 25th, 50th, and 75th percentiles of blood glucose values. These three curves illustrate the median level of control and provide an index of variability in control at each hour of a "typical day." We observed distinctive AGPs related to the variability in metabolic control and the type of diabetes. Comparisons between diagnostic groups showed consistent differences between groups, independent of level of glycemic control. Review of serial AGPs obtained for sequential 2-wk periods for 23 non-pregnant individuals with type I diabetes and 10 women with gestational diabetes revealed changes in AGP corresponding to alterations in regimen. The AGP provides a new approach to the evaluation of glycemic control, with applications to patient and physician education, clinical investigation, and individual patient care.

Adult↗
PubMedDate not supplied

Computer simulation of plasma insulin and glucose dynamics after subcutaneous insulin injection.

We developed a computer program for the simulation of plasma insulin and glucose dynamics after subcutaneous injection of insulin. The program incorporates a pharmacokinetic model to calculate the time courses of plasma insulin for various combinations of popular preparations (regular, NPH, lente, and ultralente). With the use of a pharmacodynamic model describing the dependence of glucose dynamics on plasma insulin and glucose levels, the program can predict the expected time course of plasma glucose in response to a change in carbohydrate intake, insulin dose, timing, or regimen. A set of typical parameters has been obtained by analysis of data from the literature. The results of several computer simulations are presented showing the effect on a 24-h insulin and glucose profile of systematically changing insulin regimen, dose, timing of meals, or timing of preprandial insulin administration. The program can be used to explore on a theoretical basis the impact of various factors associated with glycemic control in insulin-dependent diabetes mellitus. As an educational tool, the program provides a realistic environment for demonstration of the combined or isolated effects of insulin and diet on glycemia.

Absorption↗
PubMedDate not supplied

Personal computer programs to assist with self-monitoring of blood glucose and self-adjustment of insulin dosage.

We have developed computer programs in compiled BASIC for the IBM-PC and compatible microcomputers for use by physicians, paramedical personnel, and/or patients to assist with self-monitoring of blood glucose (SMBG) and self-adjustment of insulin dosage. The programs can potentially assist with patient education and motivation, and provide: a customized "electronic notebook" for storage and retrieval of information on blood glucose, insulin dosage, hypoglycemic reactions, urinary ketones, diet, activity, weight, illness, apparent explanations for hypoglycemic reactions or glucose values outside target ranges, and comments; graphic displays of glucose and insulin versus date, and of a "glucose profile" versus time of day or versus day of the week; simple and detailed statistical analyses; a legible summary of data; a facility to permit the physician to prepare a "customized treatment plan" for each patient, involving a choice of six regimens, target levels for each of eight time periods, four supplement tables (when well or sick, before meals, or at bedtime), rules to reduce insulin in response to hypoglycemic reactions or documented hypoglycemia, rules to increase routine insulin doses in response to persistent unexplained hyperglycemia, and rules when the patient should call the physician; suggestions regarding compensatory supplements and adjustments of routine insulin dosage; explanations why various insulin dosages should or should not be altered, and why various glucose values should be tested; comparisons of the insulin dosage administered by the patient and the recommendations of the program, together with explanations for discrepancies offered by the patient, to help evaluate compliance. The program is "user-friendly," easy to learn, and easy to use.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Glucose↗
PubMedDate not supplied

Potential role of computers in clinical investigation and management of diabetes mellitus.

Computers are likely to play an increasingly important role in the clinical investigation and management of patients with diabetes. The applications fall primarily into four areas: 1) data-base systems in clinics, hospitals, and research centers to facilitate surveillance of patients and analysis of data; 2) personal microcomputers for use by physicians and patients in storing, analyzing, and transmitting data; 3) portable devices to provide recommendations regarding insulin dose for patient use; and 4) memory-equipped glucose meters that provide verified data and have associated software with the capacity for sophisticated graphic and statistical analysis and detection of trends. An important outgrowth of the memory-based meter and the personal microcomputer is the ambulatory glucose profile (AGP). This is a display of the average pattern of glucose throughout the day, usually based on data from a 2-wk period. The AGP shows the median blood glucose, range, and 25th and 75th percentiles for each hour or in relationship to meals. By virtue of signal averaging in the presence of large random variability, this display may reveal patterns that are not evident on individual days.

Blood Glucose↗