Diurnal variations in responsiveness of the hypothalamo-pituitary-adrenocortical axis of the rat

Hypothalami, anterior pituitary gland segments and adrenal glands were removed from female Wistar-derived rats decapitated at various times of the day. Blood and tissue hormone concentrations were measured and the tissues challenged with appropriate stimuli in vitro. Both bioactive and immunoreactive corticotrophin-releasing factor (CRF) content of the hypothalami were significantly higher in the evening than in the morning, as was the basal release of bioactive CRF in vitro. The response of the hypothalami to serotonin or acetylcholine added in vitro did not change with time of day. Basal bioactive and immunoreactive adrenocorticotrophin (ACTH) release from the anterior pituitary gland was significantly increased in the evening, as was the response to synthetic ovine CRF in vitro. Plasma ACTH concentrations in intact rats given crude CRF (hypothalamic extract) in vivo were higher in the evening at all times after injection tested, but this difference was markedly reduced in animals with mediobasal hypothalamic lesions. Corticosterone released basally from adrenal glands in vitro was significantly increased in the evening and the response to added ACTH 1-24 was slightly enhanced. For adrenal glands removed from lesioned rats, the pattern was reversed, corticosterone release in vitro being lower in the evening for all doses of ACTH added. Similarly in vivo, in intact rats given ACTH 1-24, plasma corticosterone concentrations and corticosterone release in vitro from adrenal glands removed after the injection were higher in the evening. After the placement of basal hypothalamic lesions, the situation was reversed, the response to ACTH administration in vivo being greater in the morning.(ABSTRACT TRUNCATED AT 250 WORDS)

Assay methodology for quantification of the ester and ether glucuronide conjugates of diflunisal in human urine

Diflunisal is a salicylate derivative with analgesic and anti-inflammatory properties. It is excreted in the urine as an ether glucuronide, a 1-O-acyl glucuronide and as unchanged drug. The 1-O-acyl glucuronide rearranges to isomeric esters of glucuronic acid under neutral to alkaline pH conditions. The development of a urine assay for the conjugates enables the elucidation of diflunisal non-linear pharmacokinetics. The assay quantitates the ether and ester glucuronides and free diflunisal in urine at 0.5-1.0 micrograms/ml. Analysis of the glucuronides does not require authentic standards.

An improved dispersed adrenal cell assay for corticotropin in rat plasma

The present study was designed to improve the dispersed adrenal cell technique for determining adrenocorticotrophic hormone (ACTH) concentrations in small amounts of rat plasma. Priming with ACTH, incubation with methyl-isobutylxanthine, or dexamethasone pre-treatment were employed as modifications. Of these, only dexamethasone pre-treatment increased the sensitivity of the assay. The adrenal fragments obtained from 10-12 adult male rats pre-treated with dexamethasone (100 micrograms/kg B.W.) one hour before sacrifice, were digested with collagenase and deoxyribonuclease solution for 30 minutes. The dispersed cells were collected by centrifugation and resuspended in Krebs-Ringer bicarbonate buffer containing 0.2% glucose and 0.5% bovine serum albumin. Aliquots of cell suspension (3-4 X 10(4)/tube) were incubated with various doses of ACTH1-24 or the eluate of plasma samples at 37 degrees C for 2 hours in an atmosphere of 95% O2/5% CO2 in a Dubnoff shaker. The quantity of corticosterone produced was measured fluorimetrically. The assay is precise (lambda = 0.06), extremely sensitive (10 fg/tube), and convenient. One skilled technician can handle 15 to 20 plasma samples per day using 10 rats as the source of assay cells. ACTH can be measured in as little as 10-50 microliters of eluate.

Relation of family history of hypertension to platelet aggregation, ratio of total cholesterol to HDL cholesterol and urinary kallikrein excretion

Some of the relatively easily measurable and possibly hypertension-associated parameters were evaluated in thirty normotensive young subjects divided into the PHT (either parent hypertensive) group and the PNT (both parents normotensive) group. In subjects of the PHT group, the platelet aggregating sensitivity to the arachidonic acid and the ratio of total cholesterol to HDL cholesterol were significantly (p less than 0.05) increased while urinary kallikrein excretion was decreased without simultaneously significant elevation of blood pressure. The enhanced platelet aggregating sensitivity to the arachidonic acid and the increased ratio of total cholesterol to HDL cholesterol suggest that subjects with a positive family history of hypertension might have a greater tendency to atherosclerosis and could contribute to the development of essential hypertension. Decreased urinary kallikrein excretion suggests that the vasodepressive activity of the kallikrein-kinin system might be inhibited in subjects with a positive family history of hypertension.

Effect of product inhibition on elimination kinetics of ethoxybenzamide in rabbits. Analysis by physiological pharmacokinetic model

In our previous study [Lin, Sugiyama, Awazu, and Hanano: J. Pharmacokin. Biopharm. 10,649 (1982)], we successfully applied a physiological pharmacokinetic model to quantitative prediction of the elimination and distribution kinetics of ethoxybenzamide in rats and rabbits. The predictions of the time course of ethoxybenzamide concentrations in plasma were good at lower doses (10 and 20 mg/kg), whereas those at high dose (80 mg/kg) were poor. In the present study, therefore, product inhibition was suspected and examined. Product inhibition of ethoxybenzamide deethylation by its metabolite, salicylamide, was demonstrated both in vivo and in vitro studies. The plasma disappearances of ethoxybenzamide after a 20 mg/kg iv injection were determined both in the control and the salicylamide-treated rabbits. In the salicylamide-treated rabbits, the plasma disappearance of ethoxybenzamide was significantly delayed compared to that in control rabbits. This delay was quantitatively explained by the physiological pharmacokinetic model taking the competitive-type of product inhibition into consideration. The apparent dissociation constant for the salicylamide-enzyme complex in vivo was estimated as 0.14 mM. The inhibition of ethoxybenzamide de-ethylation by salicylamide was observed also in in vitro study using liver microsome of rabbits.

Corrosion product formation sequence on Cu-rich amalgams in various solutions

A single particle and four blended Cu-rich amalgam systems were immersed in 37 degrees C solutions for 1-20 months in order to determine the characterization and sequence of corrosion product formation. X-ray diffraction and SEM/EDS were used to characterize the products. The same sequence of formation occurred in all systems in Ringer's and 0.1% Ringer's solutions. The times at which each product formed varied with the brand of the amalgam and the concentration of the solution. The initial products were ZnSn(OH)6 in Zn-containing systems and SnO2 in most other systems. Cu2O formed next, followed by CuCl2 X 3Cu(OH)2. Immersion in 1% Na2S yielded only HgS on all brands. A combination of 1% Na2S and Ringer's solution yielded CaSn(OH)6 after 2 months and Cu2O at later periods. Artificial saliva resulted in a retardation of corrosion product formation and only limited amounts of a Sn-rich product could be found after 20 months. Interactions of the various components appear to alter the nature and rate of corrosion product formation on these systems and additional systematic investigations are necessary to understand the influence of these interactions on corrosion.

Effects of organic anions on the uptake of 1-anilino-8-naphthalenesulfonate by isolated liver cells

Uptake of the fluorescent probe, 1-anilino-8-naphthalene-sulfonate (I) into isolated rat liver cells was studied using both fluorescence and filtration methods. The time course of the fluorescence enhancement of I after addition to the isolated liver cells was analyzed in terms of rapid, medium, and slow phases. The slow phase (half-time approximately 7 min) was characteristic of viable cells. The fluorescence enhancement was proportional to the amount of I taken into the cells, as measured by the filtration method. The uptake of I followed Michaelis-Menten kinetics with an apparent Km of 39 microM and Vmax of 1.4 nmole/10(6) cells/min. The temperature coefficient (Q10) of the uptake of I was found to be approximately 1.9. No pH optimum was observed, and various metabolic inhibitors did not affect the uptake of I. Among the amino acid reagents used, only 2,4-dinitrofluorobenzene decreased the uptake of I (by approximately 45%). The effects of various organic anions on the uptake of I were measured. The inhibition of the uptake of I by sulfobromophthalein could be analyzed in terms of competitive inhibition; the slight inhibition by sodium taurocholate could not. It is concluded that the uptake of I is a carrier-mediated facilitated process, and that the carrier is common to both I and sulfobromophthalein.

Effect of pregnancy on the pharmacokinetics of acetaminophen in rats

Acetaminophen (A), in single doses of 15 mg/kg and 300 mg/kg, was administered by i.v. injection to nonpregnant (180-240 g) and 20 days pregnant Lewis rats (250-330 g). Blood samples (for plasma) and urine were collected serially and analyzed by high-performance liquid chromatography for A, A glucuronide and A sulfate. Serum inorganic sulfate concentrations were determined in a separate study. With respect to the 300-mg/kg dose, pregnant animals exhibited a significant decrease in relative (body weight normalized) total clearance and no change in absolute total clearance, no change in relative apparent volume of distribution and a significantly increased biological half-life. As a fraction of the administered dose, pregnant animals excreted more A, less A sulfate and the same fraction of A glucuronide as did nonpregnant animals. Pregnancy had no apparent effect on base-line serum inorganic sulfate concentration. Both normal and pregnant rats became inorganic sulfate-depleted after injection of A, 300 mg/kg. The relative total clearance of the 300-mg/kg dose of A decreased with increasing litter size, whereas the relative apparent volume of distribution was unaffected. The relative total clearance of a 15 mg/kg dose of A was much higher than that of the 300-mg/kg dose and approximated liver plasma flow rate; it was not changed by pregnancy. The relative renal clearances of A glucuronide, A sulfate and creatinine were decreased in pregnancy, whereas the absolute renal clearances of the two conjugates and creatinine were unaffected. Comparative assessment of the effect of pregnancy on the pharmacokinetics of A and other drugs in different species requires consideration of possible dose dependence and of the implications of normalizing clearance and volume of distribution values.

Microstructures of Cu-rich amalgams after corrosion

In vitro corrosion of Cu-rich amalgams resulted in selective attack of the η' phase. Copper was removed, and SnO2 products were found in pores and along matrix grain boundaries. The corrosion process greatly accelerated the γ 1→β1 transformation.

Physiological pharmacokinetics of ethoxybenzamide based on biochemical data obtained in vitro as well as on physiological data

Ethoxybenzamide (EB) concentrations in plasma and various tissues were simulated using a physiological pharmacokinetic model. The biochemical parameters, such as plasma and tissue binding constants and Michaelis-Menten constants for EB deethylation, which were needed for these simulations, were, however, obtained from in vitro data. The simulations predicted well the observed data in plasma and various tissues of the rat. Furthermore, animal scale-up predicted reasonably well the concentrations of EB in plasma and various tissues of the rabbit from data gathered in rats.

In vitro and in vivo evaluation of the tissue-to-blood partition coefficient for physiological pharmacokinetic models

An important parameter used in physiologically based pharmacokinetic models is the partition coefficient (Kp), which is defined as the ratio of tissue drug concentration to the concentration of drug in the emergent venous blood of the tissue. Since Kp is governed by reversible binding to protein and other constituents in blood and tissue, an attempt was made here to estimate the Kp values for a model drug ethoxybenzamide (EB) by means of in vitro binding studies and to compare these Kp values to those obtained from in vivo kinetic parameters observed following the administration of EB by two different routes, i.e., i.v. bolus injection and constant rate infusion. The Kp values obtained by using these three different methods were in reasonably good agreement suggesting that binding data obtained in vitro can successfully be used to estimate in vivo distribution.

Atypical measles syndrome: pathologic and serologic findings

The clinical course of measles occurring in 17 adolescents who had previously received killed measles vaccine is described. All adolescents had a peripheral dermatitis. Fifteen had characteristic pulmonary infiltrates. Serologic study in six adolescents using immunoprecipitation of 35S-methionine-labeled measles virus antigens revealed that 5/6 acute sera lacked antibody to the hemolysin antigen whereas 5/6 sera contained antibody to hemagglutinin antigen. Skin biopsies, obtained from three patients, demonstrate a combination of an Arthus reaction and delayed hypersensitivity. The typical measles histologic complex was absent. Measles virions were seen in the deep dermal blood vessels. The serologic and histopathologic presentation of this disease indicates that killed vaccine does not adequately induce antibody to the hemolysin (F) which is necessary to prevent cell-to-cell spread of paramyxoviruses. Killed vaccine does, however, produce hemagglutinin antibody and simultaneously incites later hypersensitivity to wild virus infection, producing the unusual dermatopathologic reaction seen.

A case of leukemic reticuloendotheliosis responding to oxymetholone

A 63-year-old man presented with fever, easy bruisability, splenomegaly and pancytopenia. Bone marrow aspiration was unsuccessful, and marrow biopsy revealed crowding by sheets of mononuclear cells; a diagnosis of leukemic reticuloendotheliosis (LRE) was made and the patient underwent splenectomy. There was no hematologic improvement, and the patient continued to have a significant requirement for erythrocytes and platelet transfusions. Within two months of beginning oxymetholone therapy (50 mg orally three times a day) the patient's platelet count had normalized, followed by improved erythrocyte and leukocyte counts. When the drug was discontinued, the peripheral blood counts deteriorated drastically; he again demonstrated hematologic improvement when oxymetholone therapy was reinstated. We feel that by demonstrating a hematologic response to oxymetholone, relapse when it was withdrawn, and another remission upon readministration, that we have provided stronger evidence than previously reported for the efficacy of this drug in LRE.

Computed tomography of the normal and abnormal superior sagittal sinus

The appearances on computed tomography (CT) of the normal and abnormal superior sagittal sinuses are presented. The varied patterns of non-enhanced and enhanced normal superior sagittal sinuses are correlated with and reflect the findings of anatomical dissection. Cases of abnormal superior sagittal sinus include thrombosis, brain death and sinus displacement.

Effect of experimental renal failure on sulfate retention and acetaminophen pharmacokinetics in rats

The investigation was designed to determine the effect of experimental renal failure on the retention of free (inorganic) sulfate and on the pharmacokinetics of acetaminophen in rats. Adult male Sprague-Dawley rats with renal failure produced by uranyl nitrate treatment or ligation of ureters had much higher serum free sulfate concentrations (about 2 and 5 mM, respectively) than normal animals (about 1 mM). The time-averaged total clearance of a 100-mg/kg dose of acetaminophen was higher in animals with renal failure than in normal rats and was positively correlated with serum free sulfate concentration (r = 0.76, P less than .001). Renal failure had no effect on the total clearance of a 15-mg/kg dose of acetaminophen, apparently because free sulfate was not appreciably depleted by this small dose. A 6-hr infusion of acetaminophen, at 36 mg/kg/hr, produced steady-state plasma concentrations of about 20 micrograms/ml within 2 hr in renal failure (ureter-ligated) animals, whereas in normal animals the plasma concentrations increased continuously to about 100 micrograms/ml at 6 hr. Free sulfate concentrations in serum at the end of the infusion were about 0.2 mM in normal animals and generally greater than 1 mM in the renal failure animals. The rats with renal failure converted most of the administered dose to acetaminophen sulfate, whereas normal animals metabolized much of the drug to acetaminophen glucuronide. These observations demonstrate the important effect of the endogenous free sulfate level in the body on the elimination kinetics and metabolic fate of a drug that is subject to conjugation with sulfate.

Cu2O and CuCl2 . 3Cu(OH)2 corrosion products on copper rich dental amalgams

In addition to Sn-rich corrosion products found in conventional amalgams, Cu-rich amalgams also form Cu-containing corrosion products. The nature of these Cu-rich products was investigated by immersion of samples of 13 Cu-rich amalgam systems in Ringer's solution for prolonged periods. SEM/EDS and x-ray diffraction studies were used to identify the compounds formed and their morphology. Two products were identified: Cu2O, a red product, and CuCl2 . 3Cu(OH)2, a green product.

Correlation between in vitro and in vivo drug metabolism rate: oxidation of ethoxybenzamide in rat

In vitro and in vivo correlations of the microsomal oxidation of drugs were examined, using ethoxybenzamide as a model drug. Ethoxybenzamide disappearance time course from rat plasma in vivo was analyzed by a two-compartment model assuming a Michaelis-Menten type elimination process. Ethoxybenazmide oxidation in vitro was measured by the appearance rate of salicylamide in rat liver microsomal suspension. Parameters obtained were Vmax = 3.46 and 3.77 mumoles/min/kg body weight and Km = 0.378 and 0.192 mM, in vitro and in vivo, respectively.

Sensitive colorimetric determination of cholesterol in dairy products

Cholesterol can be determined colorimetrically in dairy products at levels of larger than or equal to 10 mug (coefficient of variation = 5.3%) with an o-phthalaldehyde reagent when non-cholesterol lipids are eliminated prior to color development. Absorbance for 2 mg tripalmitin was found to be equivalent to about 20 mug cholesterol. Saponification followed by hexane extraction removed interfering lipids. Using the described procedure, 238 individual raw milk samples were found to contain 144.4+/-37.9 mug cholesterol/ml, while their skim milk portions had 26.5+/-6.4 mug cholesterol/ml (mean +/- standard deviation). The o-phthalaldehyde cholesterol estimates agreed with those obtained by a gas-liquid chromatographic procedure when cheese and ice cream were analyzed by the colorimetric procedure with and without prior fat extraction.

Microcirculation in diabetes mellitus: a study of gingival biopsies

Gingival biopsy specimens from 24 diabetic patients, six obese persons, and six controls were studied statistically and morphologically to detect vascular basement membrane changes using a proposed classification of microvessels. Statistically significant basement membrane thickening is seen in all diabetic groups in most true capillaries and vessels proximal to them, especially in terminal arterioles and metarterioles, although the degree and extent of the changes vary among different clinical groups and vessel types. The basement membrane thickening is characterized by increased amorphous, granular, and fibrillary material with occasional scattered collagenous fibrils. Although nonspecific, basement membrane thickening in microvessels at, and especially proximal to, the level of true capillaries is intimately related to diabetes. Gingival biopsy may possibly be used as an adjunct in the diagnosis of diabetes.