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Biomedical subjects

C C Peck

Publications and source records attributed to C C Peck.

At least 73 records · Page 4Linked to original sources
PubMed1982

Toxic potential of the plasticizer Di(2-ethylhexyl) phthalate in the context of its disposition and metabolism in primates and man.

Although human toxicity from exposure to the plasticizer di(2-ethylhexyl) phthalate (DEHP) is unknown, reports of animal toxicity from DEHP have stimulated extensive toxicological studies. In the absence of direct toxicity data, information on the disposition and metabolism of DEHP in primates and man may enhance our assessment of the toxic potential of DEHP in man. Studies of DEHP disposition and metabolism in the African Green monkey and man show that the compound is rapidly and extensively metabolized. It is excreted largely in the urine (greater than 90%) as conjugated (glucuronide) oxidation products of mono(2-ethylhexyl) phthalate; excretion in feces accounts for the other 10% of the administered DEHP. Plasma disappearance of parenterally administered DEHP is equally rapid so that by 24 hr following DEHP administration, plasma DEHP concentrations are virtually undetectable, while greater than 70% of the dose has been excreted in urine and stool. The transience of DEHP in primates and the extent to which it is metabolized and conjugated may play a role in the observed lack of toxicity.

Animals↗
PubMed1981

Continuous transepidermal drug collection: basis for use in assessing drug intake and pharmacokinetics.

Continuous transepidermal drug collection (CTDC) has been proposed for use in assessing ethanol intake and in monitoring compliance with therapeutic regimens. Exploration of a theoretical basis for use of CTDC in these circumstances and for its use in assessing other aspects of drug disposition kinetics was undertaken. Effects of single and multicompartmental drug disposition models, single dose and multiple dose regimens, with regular and irregular doses and dosing intervals, and zero-order, first-order, and Michaelis-Menten excretion patterns were explored. First-order transepidermal drug transfer was assumed with and without back transfer from the collection device. These analyses suggest that the utility of CTDC is severely restricted when back transfer from the collection device is substantial. With back transfer minimized, CTDC may be a useful tool for assessing amount of drug exposure, compliance with therapeutic regimens, and relative bioavailability, but offers little advantage over discrete sampling of other body fluids in the study of other aspects of drug disposition kinetics.

Half-Life↗
PubMed1981

An evaluation of the effects of lithium in the treatment of chronic alcoholism. I. Clinical results.

To evaluate the efficacy of lithium in chronic alcoholism, we enrolled 47 male alcoholics in a prospective double-blind two-period crossover study. Nineteen subjects completed the 6-mo study during which they received lithium and placebo each for a 3-mo period. Self-reported alcohol intake and social and psychological factors were monitored. Three subjects claimed that they did not drink during the study. Mean self-reported alcohol intake of the remaining 16 was less during lithium therapy but was also less during the first treatment period. Neither of these differences reached statistical significance. The nine depressed patients, diagnosed from their profiles of the Minnesota Multiphasic Personality Inventory did not consume significantly less alcohol and did not change scores for depression significantly during lithium therapy. We could not demonstrate the lithium therapy was of benefit in our group of alcoholic patients.

Adult↗
PubMed1981

An evaluation of the effects of lithium in the treatment of chronic alcoholism. II. Assessment of the two-period crossover design.

Analysis of self-reported alcohol intake by alcoholic subjects participating in a two-period crossover trial of lithium versus placebo failed to demonstrate a significant effect of lithium in reducing alcohol consumption. An appraisal of the adequacy of this study design to meet the original objective of the trial was undertaken. It was impossible under this study design to simultaneously and unequivocally estimate effects of treatment periods, drug carryover, sequence group and other period by treatment interactions in addiction to the lithium/placebo effects. Presence of one or more of these additional influences on the trial outcome not only complicated the interpretation of results but diminished the power of the trial design to test the major hypothesis of interest, that lithium could reduce alcohol intake. We conclude that the two-period crossover design has serious drawbacks in this clinical trial setting and that alternative strategies need to be considered for future trials.

Adult↗
PubMed1981

Adenine in blood preservation.

The recent Food and Drug Administration (U.S.) approval of a new blood preservative (CPDA-1) which contains adenine not only introduces a new blood product into the American blood banking system, but also heralds the advent of novel approaches to blood product preservation. The use of adenine to effect maintenance of red cell adenosine triphosphate (ATP), and hence to prolong storability, has a well-founded biochemical rationale. Effects of adenine on red cell metabolism are generally well understood, but effects on other blood components have not been fully delineated. The efficacy of adenine preservatives in enhancing the duration of red cell storage appears to outweigh the small risk of toxicity from free adenine. Clinical use of millions of units of adenine-preserved blood in Europe during more than a decade has resulted in only one report of possible adenine toxicity. Marginal acceptability of 24-hr 51Cr red cell recovery of packed red cells stored for 35 days in CPDA-1 has stimulated development and evaluation of an improved preservative (CPDA-2) which may extend blood storability beyond 35 days. A heightened awareness of the hematological consequences of prolonged storage has come with the extension of blood storage beyond 21 days. The concepts of component-specific preservation systems and optimal preservation systems have emerged as a result of experimentation on adenine preservatives. While the influence of adenine preservatives on American blood banking is yet to become manifest, the ultimte impact of adenine on blood preservation may be the development of novel systems which optimally preserve specific blood components at the option of the user.

Adenine↗
PubMed1979

Erythema multiforme and urticaria. Eruptions induced by chemically related ophthalmic anticholinergic agents.

Erythema multiforme developed in an 80-year-old man following the use of scopolamine hydrobromide ophthalmic drops. The erythema multiforme cleared when the medication was discontinued and recurred on challenge. Later, he was given tropicamide, an anticholinergic ophthalmic preparation that, like scopolamine, has a tropic acid residue. Within 15 minutes an immediate hypersensitivity reaction with generalized urticaria developed in the patient.

Aged↗
PubMed1979

Nonlinear least-squares regression programs for microcomputers.

Nonlinear least-squares regression can be performed on a microcomputer with BASIC language capability and 8K or more bytes of random access memory. At least five nonlinear regression programs written in BASIC exist, two of which have been implemented on microcomputers. These programs and some of their characteriscics are described. Advantages and disadvantages of performing nonlinear regression on microcomputers are contrasted with use of nonlinear regression programs requiring large computers.

Computers↗
PubMed1978

General method for determining macrodissociation constants of polyprotic, amphoteric compounds from solubility measurements.

Equilibrium solubility and pH measurements can be used to determine macrodissociation constants of weak acids and bases of some highly insoluble substances. Equations are derived extending solubility, pH, and pKa (macroscopic) relationships to polyprotic, amphoteric substances. A general method for estimating pKa values, given a set of solubility and pH measurements, is presented. Included in the estimation procedure is a subroutine for approximating thermodynamic pKa values. The method was tested on two data sets (tyrosine and 2,3-dihydroxyadenine) and rendered pKa (thermodynamic) estimates in close agreement with those using other methods.

Acids↗
PubMed1978

Alterations in intestinal structure, fat absorption and body weight after intestinal bypass for morbid obesity.

Eleven patients underwent jejunoileal bypass for morbid obesity. Serial intestinal biopsies were obtained prior to, and at timed intervals following, operation in both fasted and fat-fed states. Villus height increased asymptotically, reaching a plateau one year after operation, with an increase of 80 per cent in mean villus length. The postbypass body weight reached a plateau at 63.9 per cent of initial body weight and correlated linearly with villus height following an asymptotic curvilinear course. The time required to attain 90 per cent of total body weight loss was 15.9 months. A study of intestinal fat absorption at both the light microscopic and ultrastructural levels showed that the enlarged villi are lined along the entire villus by functionally mature epithelium capable of transporting lipid. Villus hypertrophy is an important mechanism in the plateauing of weight loss after jejunoileal bypass for morbid obesity.

Body Weight↗
PubMed1977

Serum and urinary amylase levels following pulsatile and continuous cardiopulmonary bypass.

The incidence of elevated serum and urine amylase values was examined in a prospective clinical study of patients subjected to either continuous or pulsatile extracorporeal perfusion. Mean postoperative values for urine and serum amylase were higher in the continuous group, and the incidence of abnormal values was also greater in the continuous group (70 percent versus 32 percent, p less than 0.01). Clinical pancreatitis was absent in both groups. This study documents a high incidence of elevated amylase values following bypass with either modality and provides evidence for possible improved visceral circulation with pulsatile extracorporeal bypass during routine cardiac operations.

Adult↗
PubMed1976

Ineffectiveness of human chorionic gonadotropin in weight reduction: a double-blind study.

Our investigation was designed to retest the hypothesis of the efficacy of human chorionic gonadotropin (HCG) on weight reduction in obese women in a clinic setting. We sought to duplicate the Asher-Harper study (1973) which had found that the combination of 500 cal diet and HCG had a statistically significant benefit over the diet and placebo combination as evidenced by greater weight loss and decrease in hunger. Fifty-one women between the ages of 18 and 60 participated in our 32-day prospective, randomized, double-blind comparison of HCG versus placebo. Each patient was given the same diet (the one prescribed in the Asher-Harper study), was weighed daily Monday through Saturday and was counselled by one of the investigators who administered the injections. Laboratory studies were performed at the time of initial physical examinations and at the end of the study. Twenty of 25 in the HCG and 21 of 26 patients in the placebo groups completed 28 injections. There was no statistically significant difference in the means of the two groups in number of injections received, weight loss, percent of weight loss, hip and waist circumference, weight loss per injections, or in hunger ratings. HCG does not appear to enhance the effectiveness of a rigidly imposed regimen for weight reduction.

Adult↗