Metabolism of D(-)lactic acid in rats given high intragastral doses

In rats given D[u-14C]-labelled DL-lactate with 3.8-13.4 mmol D-lactate per kg 0.75 by stomach tube, the exhalation of CO2 produced from and the renal excretion of D-lactate and metabolites were measured. Exhalation of D-lactate-C accounted for 45-30% of the dosage given with a decreasing proportion at higher doses. The renal excretion of D-lactate averaged 0.9% and that of metabolites from D-lactate 2.4% of the doses given. The fraction of unrecovered D-lactate accounted for about 54-68% of the doses given and increased with doses. The time course of D-lactate oxidation indicated a maximum rate of about 1.5 mmol C per kg 0.75 in 1 hr which was reached at 1 hr after infusion at the earliest and extended up to 8 hr if high doses were given.     

The benzodiazepine receptor antagonist, flumazenil does not block clinical effects of delta-9-tetrahydrocannabinol

Fifteen normal volunteer men were given intravenous doses of 2 mg of delta-9-tetrahydrocannabinol (THC) and 3 were given doses of 0.5 mg. Five, 15 and 30 minutes later, they were given intravenous doses of the benzodiazepine receptor antagonist, flumazenil. Doses of this compound ranged between 0.1 and 3.2 mg for single doses and 0.7 and 6.4 mg for total doses, being increased progressively with each successive subject, until dose-ranging was completed in 10 subjects. After that 5 subjects were given doses of 2 mg of THC on two occasions, followed by either doses of 3.2 or 6.4 mg flumazenil or placebo, administered under blind conditions. Three subjects were treated with 0.5 mg doses of THC followed by 3.2 mg of flumazenil or placebo under similar conditions. Despite doses of the antagonist which would have been adequate to reverse the effects of substantial doses of benzodiazepines, little ameliorative action was observed on the level of intoxication or the degree of conjunctival injection, two quite reliable clinical indicators of THC action. The benzodiazepine receptor does not seem to play any significant role in the psychoactive actions and conjunctival injection produced by THC.     

Eimeria acervulina, E. brunetti, and E. maxima: immunity in chickens with low multiple doses of mixed oocysts.

Young chickens inoculated with multiple low doses of mixed oocysts of Eimeria acervulina, E. brunetti, and E. maxima had a high level of resistance to reinfection with a mixed challenge dose on Day 28, Day 84, or Day 140. Immunity was enhanced when the number of immunizing doses was increased from three to four. Resistance was also high in birds maintained on a proprietary mixture of amprolium, ethopabate, and sulphaquinoxaline (Pancoxin-Merck, Sharp and Dohme Ltd.) during immunization, although immunity to E. acervulina was lower in these birds. Oocyst production was lower in birds given mixed infections as compared with that of birds given pure infections with similar doses of oocysts. Competition between species did not inhibit the development of immunity in birds given low doses of mixed oocysts.     

Low-dose meningeal worm (Parelaphostrongylus tenuis) infections in moose (Alces alces)

Parelaphostrongylosis has a rapid onset and is lethal in neonatal moose (Alces alces) when large numbers of third-stage Parelaphostrongylus tenuis larvae (L3) are given experimentally. Little is known, however, about the severity and prognosis of infections acquired naturally by accidentally ingesting terrestrial gastropods which are rarely infected and have few larvae. To investigate the relationship between infecting dose, age of moose, and severity of disease, five calves were given low doses of three to 10 L3 when five (n = 2) or 9.5 mo old (n = 3). Each of two animals initially given low doses were later challenged with a dose of 15 L3. As positive controls, two calves were given doses of 15 and 30 L3, considered to be high. All five calves given low doses showed abnormal locomotory signs at 20-28 days postinoculation (DPI) that progressively became more pronounced with hind quarter weakness and front lameness. However, after 77-130 DPI, signs diminished markedly in two of these animals and disappeared in another two. Challenge infections of 15 L3 given 199 days after initial infections had no noticeable effects although an immature worm, probably resulting from the challenge, was found in the spinal cord of one animal killed 51 days later. Two positive control animals given the high doses of 15 and 30 L3 showed moderate to severe, non-resolving, locomotory signs and had to be euthanized. Results demonstrate that single, low doses of three to 10 P. tenuis L3 cause moderate disease in moose calves but over time, some worms die and animals can recover. A degree of protection may develop against future infection.     

Pyridoxine and atherosclerosis: role of pyridoxine in the metabolism of lipids and glycosaminoglycans in rats fed normal and high fat, high cholesterol diets containing 16% casein

The effect of administration of low and high doses of pyridoxine on the metabolism of lipids and glycosaminoglycans has been studied in rats fed normal and high fat, high cholesterol diets. Low doses of pyridoxine (0.005 mg/100 g body weight) caused increased concentrations, of cholesterol and triglycerides in the serum and aorta in animals fed normal and high fat, high cholesterol diets. Administration of high doses of pyridoxine (5.0 mg/100 g body weight) caused decrease in the concentration of these lipids in these tissues except in the case of the aorta in the animals fed a normal diet. Low doses of pyridoxine generally caused a decrease in the concentration of many glycosaminoglycan fractions in the aorta in rats fed normal and high fat, high cholesterol diets, whilst high doses caused an increase. The activity of glucosaminephosphate isomerase (glutamine-forming) and UDPglucose dehydrogenase, both key enzymes in the biosynthetic pathway of glycosaminoglycans, decreased in rats given low doses of pyridoxine and increased in rats given high doses. The activity of many enzymes concerned with degradation of glycosaminoglycans--hyaluronoglucosidase, beta-glucuronidase, beta-N-acetylglucosaminidase, aryl sulphatase, and cathepsin D--generally increased in rats fed low doses of the pyridoxine and decreased in those given high doses. The concentration of hepatic 3'-phosphoadenosine-5'-phosphosulphate, and the activity of the sulphate-activating system and of aryl sulphotransferase decreased when the dose of pyridoxine was low and increased when the dose was high.     

Dose response kinetics of serum vitellogenin, liver DNA, RNA, protein and lipid after induction by estradiol-17 beta in male flounders (Platichthys flesus L.).

1. Male flounders receiving 100 micrograms estradiol each second day were fully induced to vitellogenin synthesis within 11 days, while fishes given 5 micrograms doses continued to accumulate vitellogenin in the serum at a progressive rate through 17 days. 2. Liver DNA per unit fish remained constant, while RNA per unit fish in flounders given 100 and 5 micrograms doses attained values 80 and 25% respectively, above the values found in control animals. 3. Liver RNA per unit DNA increased at maximal rate within 6 days in fishes receiving 100 micrograms doses. RNA synthesis continued at a progressive rate through 17 days in fishes given 5 micrograms doses of estradiol. 4. Liver protein per unit DNA elevated at a plateau 60% above control within 6 days with 100 micrograms doses. Doses of 5 micrograms had only little effect on liver protein. 5. Estradiol had a lipogenic effect on the liver. Cellular lipid rose 120 and 60% above control after treatment with 100 and 5 micrograms respectively. 6. Liver dry weight per unit DNA increased 60 and 55% above control with 100 and 5 micrograms doses respectively. Cellular hypertrophy in fishes receiving the smaller dose was primarily associated with an increase in lipid concentration, while protein and lipid contributed almost equally to cellular growth in fishes receiving the high dose.     

Multivariate slope ratio assay with repeated measurements

A method is given for analyzing a slope ratio assay in which a test drug is compared with a standard drug, two or more response variates being measured on each subject at each of several successively increased drug doses. The method requires all subjects to receive the same number of doses, all subjects on the same drug to receive the same doses, the ratio of corresponding doses of the two drugs to be constant over the successive increases, and response variables to be measured only once on each subject at each dose with no missing data allowed. The technique is also applicable when doses are randomly assigned, provided there is no carry-over effect between doses. For each of the J response variates, the relative potency of the test drug with respect to the standard is defined and estimated in the usual way; a 100(1-alpha)% confidence region is then obtained for the vector of the J relative potencies. A procedure is given for testing the equality of some or all of the J relative potencies; an estimator of a common relative potency is obtained by a standard multivariate least squares method. A common relative potency is of interest because the multiple outcome variables are often different indicators of a general physiologic response. The procedures in the paper are illustrated by a simple example concerning the effects of two anesthetics on children.     

Physiological casein and gluten protein requirements of growing rats

Using mounting casein and wheat gluten protein values (0-40%) in the animals' diet, the optimum and minimum physiological daily doses were determined in 49-day-old growing rats from changes in their body water, body nitrogen and protein intake. The optimum physiological doses were identical with the peak of linearity of the given parameters, which coincided with a 15% casein protein and a 20% gluten protein concentration in the diet. This was also confirmed by the maximum body amino acid values, which were found in animals given a 15% casein or 20% gluten protein diet. It was further confirmed by the finding of significantly elevated alanine aminotransferase and aspartate aminotransferase activity in the liver of animals with a higher intake of the above protein sources. The minimum physiological dose of the given protein was determined from the equations of the regression curves in the presence of zero changes in the body nitrogen or body water content. The optimum physiological daily doses of casein and wheat gluten protein were 3.25 g and 4.05 g respectively. The minimum physiological daily doses of casein protein were 268 mg (from body nitrogen changes) and 371 mg (from body water changes) and the minimum physiological daily doses of gluten protein were 892 mg (from body nitrogen changes) and 1,000 mg (from body water changes). The above indicators demonstrate, in the presence of higher and high dietary concentrations, that an intake of the given proteins over and above the optimum physiological daily dose is at the very least uneconomical (gluten), if not harmful (casein), making this a highly topical problem for further study.     

Acute Toxicity of Ochratoxins A and B in Chicks

Ochratoxins A and B were given to 1-day-old Babcock B-300 cockerels to evaluate acute toxic effects. Two trials with ochratoxin A gave 7-day oral median lethal dose estimates of 116 mug (3.3 mg/kg) and 135 mug (3.9 mg/kg) per chick. Chicks given daily oral doses of 100 mug of ochratoxin A died on the second day. Single subcutaneous doses of 400 mug of ochratoxin A were also lethal. The 7-day oral median lethal dose of B was estimated at 1,890 mug (54 mg/kg) per chick. Chicks given oral doses of 100 mug of ochratoxin B daily for 10 days survived. Sublethal doses of both ochratoxins A and B resulted in growth suppression which was proportional to the amount of ochratoxin given. Visceral gout was the principal gross finding. Microscopic examinations revealed acute nephrosis, hepatic degeneration or focal necrosis, and enteritis. Suppression of hematopoiesis in the bone marrow and depletion of lymphoid elements from the spleen and bursa of Fabricius were frequently seen. Both ochratoxins appeared to have similar pathological effects. This is the first report on the toxicity of ochratoxin B.     

Plasma concentrations of choline in man following choline chloride

Plasma choline levels were measured in patients being treated with choline chloride for movement disorders. Following single doses of 5 g given orally in aqueous solution, plasma concentrations rose to a peak within four hours and then rapidly declined. The degree of increase was variable both between and within patients. During chronic treatment, plasma choline concentrations tended to rise as the dose increased, although the relationship was not strong. The highest concentrations attained by patients were always at a dose of 16 or 20 g daily. Following chronic treatment, the disappearance of choline from plasma was rapid, with most patients reaching baseline by four days. Choline chloride is generally given in four divided doses, which seems reasonable in the early stages of treatment. Most therapeutic effect is seen when patients are treated with daily doses in the 12 to 20 g range, doses likely to produce substantial increases in plasma choline concentration. However, the relationship of plasma choline concentration to clinical efficacy may be tenuous. Following discontinuation of treatment, clinical improvement tends to persist long after plasma choline has returned to baseline concentrations.     

Vaccine against human hepatitis B virus prepared from antigen derived from human hepatoma cells in culture

Vaccine against human hepatitis B was prepared using antigen derived from hepatitis B carrier hepatoma cells grown in the interstices of a Diaflo hollow filter unit. Hepatitis B surface antigen (HBsAg) produced by these cells was purified by immune affinity chromatography, digestion with DNase and pepsin, and Sephadex G-150 separation. The Formalin-treated antigen was formulated in 20-micrograms dose on alum adjuvant with thimerosal added as a preservative. This cell culture vaccine was as potent as human plasma-derived vaccine as measured in a mouse potency assay. The vaccine proved safe in tests in chimpanzees and in human subjects who were in late stages of cancer of the central nervous system and who were receiving therapy for their condition. None of five subjects who received the vaccine developed untoward clinical reactions. Two of the subjects who received all three doses of vaccine developed antibody against HBsAg. Three persons, two given only the primary doses and one who was given all three doses but was lost to follow-up, demonstrated no response. The slow and relatively low antibody responses to the vaccine were similar to those in other immunosuppressed persons who were given vaccine of human plasma origin.     

Current status of cytogenetic procedures to detect and quantify previous exposures to radiation

The estimation of the magnitude of a dose of ionizing radiation to which an individual has been exposed (or of the plausibility of an alleged exposure) from chromosomal aberration frequencies determined in peripheral blood lymphocyte cultures is a well-established methodology, having first been employed over 25 years ago. The cytogenetics working group has reviewed the accumulated data and the possible applicability of the technique to the determination of radiation doses to which American veterans might have been exposed as participants in nuclear weapons tests in the continental U.S.A. or the Pacific Atolls during the late 1940s and 1950s or as members of the Occupation Forces entering Hiroshima or Nagasaki shortly after the nuclear detonations there. The working group believes that with prompt peripheral blood sampling, external doses to individuals of the order of about 10 rad (or less if the exposure was to high-LET radiation) can accurately be detected and measured. It also believes that exposures of populations to doses of the order of maximum permissible occupational exposures can also be detected (but only in populations; not in an individual). Large exposures of populations can also be detected even several decades after their exposure, but only in the case of populations, and of large doses (of the order of 100 to several hundred rad). The working group does not believe that cytogenetic measurements can detect internal doses from fallout radionuclides in individuals unless these are very large. The working group has approached the problem of detection of small doses (less than or equal to 10 or so rad) sampled decades after the exposure of individuals by using a Bayesian statistical approach. Only a preliminary evaluation of this approach was possible, but it is clear that it could provide a formal statement of the likelihood that any given observation of a particular number of chromosomal aberrations in a sample of any particular number of lymphocytes actually indicates an exposure to any given dose of radiation. It is also clear that aberration frequencies (and consequently doses) would have to be quite high before much confidence could be given to either exposure or dose estimation by this method, given the approximately 3 decades of elapsed time between the exposures and any future blood sampling.(ABSTRACT TRUNCATED AT 400 WORDS)     

A nonparametric Bayesian modeling approach for cytogenetic dosimetry

In cytogenetic dosimetry, samples of cell cultures are exposed to a range of doses of a given agent. In each sample at each dose level, some measure of cell disability is recorded. The objective is to develop models that explain cell response to dose. Such models can be used to predict response at unobserved doses. More important, such models can provide inference for unknown exposure doses given the observed responses. Typically, cell disability is viewed as a Poisson count, but in the present work, a more appropriate response is a categorical classification. In the literature, modeling in this case is very limited. What exists is purely parametric. We propose a fully Bayesian nonparametric approach to this problem. We offer comparison with a parametric model through a simulation study and the analysis of a real dataset modeling blood cultures exposed to radiation where classification is with regard to number of micronuclei per cell.     

Effect of treatment with submaximal and excessive doses of caerulein on pancreatic growth in newborn rats

Different groups of CFY female newborn rats were treated with saline, or 1 microgram/kg or 100 micrograms/kg doses of caerulein given s. c. 3 x/day. Application of 100 micrograms/kg dose of caerulein for 3 days stimulated pancreatic growth inducing pancreatic hyperplasia; both (1 and 100 micrograms/kg) doses evoked increase in trypsin/DNA ratio inducing pancreatic hypertrophy in 4-days-old rats. Using the indices as before application of 1 microgram/kg caerulein for 10 days stimulated pancreatic growth and both (1 and 100 micrograms/kg) doses elicited glandular hypertrophy in 11-days-old rats. In 24-old-rats the 1 microgram/kg doses of caerulein given for 3 days stimulated pancreatic growth and induced pancreatic hypertrophy, the 100 micrograms/kg doses of the peptide given for 3 days, however, evoked pancreatic aplasia and atrophy.     

Modulation of gastric acid secretion by adenosine in conscious rats

Basal (nonstimulated) gastric acid output was determined in conscious rats fitted with indwelling gastric cannulae. The adenosine deaminase resistant analog of adenosine, R-phenylisopropyladenosine, elevated intraluminal pH beyond 7.0 and decreased gastric acid secretion when given at doses of 0.10 or 1.0 mg/kg, while S-phenylisopropyladenosine at similar doses did not affect either gastric acid output or pH. The potent adenosine receptor antagonist, 8-phenyltheophylline, given at doses of 0.1, 1.0, and 2.5 mg/kg augmented gastric acid output and, at doses of 0.01, 0.1, 1.0, and 2.5 mg/kg, blocked the acid-reducing effect of R-phenylisopropyladenosine (0.1 mg/kg). These data suggest that adenosine systems may be important regulators of gastric function.     

Effects of hypo- and hyper-thyroidism on liver composition, blood glucose, ketone bodies and insulin in the male rat

1. Thyroidectomized rats injected daily with 0, 0.1, 2 or 25mug of l-thyroxine/100g body wt. were compared with intact controls. In plasma, the protein-bound iodine was decreased in the rats given the 0 or 0.1mug doses and increased in those given the 25mug dose. 2. Blood glucose decreased in those given 2mug and was augmented in those given 25mug, and ketone bodies were the same in all the groups. 3. Plasma insulin was lowest in the rats given the 0 or 0.1mug doses and was highest in those given the 2 or 25mug doses of thyroxine. 4. After 48h starvation, the decrease in blood glucose and increase in ketone bodies observed in all the groups was greatest in the group not supplemented with thyroxine. 5. Plasma insulin concentrations remained at the value for fed animals in the rats given the 25mug dose of thyroxine but decreased in the other groups. 6. In fed animals, concentrations of hepatic DNA P, citrate, total fatty acids and acetyl-CoA were similar in all the groups, and glycogen was low only in the rats given the 25mug dose of thyroxine. 7. After 48h starvation, liver DNA P, total fatty acids and acetyl-CoA increased in all the groups, except in the rats given the 25mug dose, where both total fatty acids and acetyl-CoA remained at the value for fed animals. Liver citrate did not change in the groups given the 0 or 25mug doses of thyroxine, but decreased in the other groups. 8. The results are discussed in relation to the regulation of intermediary metabolism in hypo- and hyper-thyroidism.     

The antibody response of seronegative infants to inactivated poliovirus vaccine of enhanced potency

The immunogenic efficacy of inactivated poliovirus vaccine of enhanced potency (IPV-E), containing 40, 8 and 32 D-antigen units of types 1, 2 and 3, respectively, was evaluated in tritypic seronegative infants. Eighty infants aged six to 45 weeks, with no antibody detectable at a 1 : 4 dilution, were given two doses of a quadruple vaccine containing diphtheria-pertussis-tetanus (DPT) vaccine and IPV-E at intervals of four weeks (37 infants, group 1) or eight weeks (43 infants, group 2) between doses. All infants of group 2 responded with antibody to the three types of polioviruses. In group 1, all responded to types 1 and 3 antigens but only 36 responded to type 2. Antibody titres were higher in infants immunized at eight week than at four week intervals. Thus, two doses of IPV-E, especially when given eight weeks apart, are sufficient for primary immunization against poliomyelitis. If DPT vaccine of enhanced potency is combined with IPV-E, two doses of such a quadruple vaccine may be sufficient for primary immunization against four diseases; this possibility deserves evaluation.     

The evaluation of a multiple dosing protocol for the mouse bone-marrow micronucleus assay using benzidine and 2,6-xylidine

Male ICR mice were treated with 1, 2 or 3 daily doses of either benzidine or 2,6-xylidine. Groups of 5 animals were sacrificed 24 h after the last dose and the bone marrow examined for micronuclei. Benzidine was given at dose levels of 40 and 200 mg/kg and 2,6-xylidine was given at dose levels of 75 and 375 mg/kg. These doses represent 10 and 50% of the respective median lethal doses. Benzidine produced a significant (p less than 0.001) dose related increase in the incidence of micronucleated polychromatic erythrocytes (MPE), while 2,6-xylidine had no effect on the frequency of micronucleated cells. Statistical analyses of the data indicated that the incidence of MPE was independent of the number of doses administered prior to bone marrow harvest.     

Relationship between the dose of 1-deamino-8-d-arginine vasopressin (ddavp) and the antidiuretic response in man.

A definite relationship was found between the dose of DDAVP (1-24 mug intravenously and 5-320 mug intranasally) and the antidiuretic effects (expressed in changes in free water clearance per 100 ml GFR and in urine osmolality determined in 24 hour urine collection periods) in 7 patients with diabetes insipidus. The relationship was more conspicuous when the second 12 hour antidiuretic responses were considered, indicating a dose-dependent prolongation of the antidiuretic action. Time-curves of the antidiuretic responses proved the dose-dependent prolongation of the duration of antidiuretic action. Second 12 hour antidiuretic response increased more markedly when DDAVP was given divided in two doses a day as compared to the effects of the same quantity of the drug given as a single dose; only by the administration of excessive single doses the effects of the divided doses could be reproduced.     

The effect of pentosan polysulphate (SP54) on the fibrinolytic enzyme system. An experimental animal study

Pentosan polysulphate (SP54) causes a transient increase in blood fibrinolysis in conscious and anaesthetized rats. Postoperative "fibrinolytic shutdown" was prevented by a dose of 2 mg/kg body weight but there appeared to be no dose-response relationship with higher doses. Fibrinolysis was also measured in conscious unstressed animals using an indwelling jugular cannula. The venous response to SP54 in these animals was substantially higher than the arterial response. Experiments with an inferior vena cava model of thrombosis suggest that a single dose of 10 mg/kg pentosan polysulphate given 90 min after thrombus formation is sufficient to achieve thrombolysis. This effect was more marked if the animals were given multiple doses over 24 to 48 hours.