Thomas F. Kellogg

The effect of sample composition and vial type on Cerenkov counting in a liquid scintillation counter

The effect of sample vial type and sample composition on the Cerenkov count rate detected from 32P and 36Cl was studied using a liquid scintillation counter. When counting was done in the noncoincident mode, glass vials allowed higher counting efficiency than plastic vials. In the coincident mode light scattering caused by polyethylene and polyproplyene vials allowed higher counting efficiency than glass vials. Highest coincident counting efficiency was from plastic minivials in a glass carrier vial. Increased solute concentration in samples caused increased counting efficiency due to changes in the refractive index of the solution. This can cause significant counting efficiency changes with no sample channel ratio change in density gradient fractions. The use of wavelength shifters is shown to be inappropriate when the sample pH varies, as this can change the fluorescent properties of the shifters and thereby the observed count rate.

Changes in Serum Lipid, Lipoprotein and Corticosterone Concentrations during Neonatal Chick Development

Broiler chicks were given a standard commercial starter diet from day 0 (day of hatch) to 9 days of age. Body weight and concentrations of the following serum constituents were measured daily: glucose (GLU), triglycerides (TRI), corticosterone (CORT), cholesterol (CHOL), and high (HDL) and low (LDL) density lipoproteins. Serum GLU and TRI increased at each sampling day to reach a peak on days 3 and 4, respectively, and then decreased thereafter. However, CHOL, HDL, and LDL decreased sharply by day 1 and then gradually decreased to day 5. Conversely, CORT peaked on day 1 and then decreased to day 4. It peaked again on day 5 and remained at that level throughout the remainder of the experiment. In summary, serum concentrations of all constituents measured fluctuated drastically between 1 and 5 days of age, with few changes occurring between days 6 and 9.

On the site of the microbiological reduction of cholesterol to coprostanol in the rat

The microbiological reduction of the 5-ene bond of cholesterol (cholest-5-en-3β-ol) to form coprostanol (5β-cholestan-3β-ol) occurs in the gastrointestinal tract of many species. Data are presented which show that this activity occurs predominantly in the ceca in cholesterol fed rats. This explains the report by others that the removal of the ceca causes coprostanol to disappear from the feces.

The biliary bile acids of the channel catfish, Ictalurus punctatus, and the blue catfish, Ictalurus furcatus☆

Abstract 1. 1. The biliary bile acids of the channel catfish, Ictalurus punctatus , and the blue catfish, Ictalurus furcatus , have been determined. 2. 2. In both species the biliary bile acids are composed of taurocholic acid: 83%— I. punctatus , 84%— I. furcatus ; taurochenodesoxycholic acid: 15%— I. punctatus , 16%— I. furcatus ; taurodesoxycholic acid: 2%— I. punctatus only. 3. 3. These bile acids are consistent with the phylogenetic placement of these species in suborder silurodei.

Triton-X-100 acts as a scintillant when used as a wavelength shifter in Čerenkov counting systems

Abstract When Triton-X-100 ∗ is added to Cerenkov counting systems as a wavelength shifter it acts as a scintillant. When Triton-X-100 is combined with other wavelength shifters such as sodium salicylate the counting efficiency for beta particles, which have insufficient energy to cause a Cerenkov response, can exceed 80%. This can cause potential errors for dual-radionuclide counting by liquid scintillation- Cerenkov counting methods.

Cholesterol metabolism in poultry, Gallus domesticus: fecal neutral sterol and bile acid excretion☆

1. 1. Fecal neutral sterol and bile acid excretion of White Leghorn pullets and laying hens, Gallus domesticus, were determined. 2. 2. Variations in poultry fecal neutral sterol excretion were detected between different ages. Neutral sterol variations correlated with egg laying capacity. 3. 3. Variations in poultry fecal bile acid excretion were detected between different ages. No correlation was found between bile acid excretion and poultry egg laying capacity. 4. 4. Variations in total poultry fecal steroid excretion were detected between different ages. No correlation was found between total fecal steroid excretion and poultry egg laying capacity. 5. 5. Intestinal microbial modification of fecal neutral sterols and bile acids varied with poultry age. No microbial modifications of fecal steroids were detected at 8 weeks of age, but were found to develop through 26 and 58 weeks of age.

A water-miscible, nonhazardous liquid scintillation cocktail

The optimal way to count aqueous samples by liquid scintillation counting is in a homogeneous solution. Technical limitations have previously made this difficult. Triton X-100 is a water-miscible liquid scintillant which counts 14C with 80% efficiency and 3H with 17% efficiency. It has a high flash point (over 300°F), is nonvolatile, and does not cause swelling or leaching when used in polyethylene vials. Liquid-scintillation counting cocktail using Triton X-100 as the sole scintillant (i.e., no toluene or xylene) does not have to be disposed of as a hazardous waste. The large aqueous sample capacity of a miscible cocktail, its safety, and ease of disposal make its use highly attractive for many applications.

Bile Acid Metabolism in Gnotobiotic Animals

The bile acid metabolism of conventional animals is an intimately related blend of effects caused by the enzymes of the host and the enzymes of the indigenous microbial flora. In the absence of pathogenic conditions, significant populations of enteric microorganisms will be found in the lower small intestine, and in the colon (and cecum if present) they will reach up to 1010 organisms per gram of intestinal contents. This microflora exerts a profound effect on the biology of the host and particularly on those systems which come into intimate contact with it.

An improved technique for the determination of respiratory 14CO2 as Ba 14CO3, utilizing thermal decomposition in a sample oxidizer

Abstract Respiratory 14CO2 radioactivity determination as Na2 14CO3 or Ba 14CO3 by liquid-scintillation counting is prone to procedural errors. Ba 14CO3 was collected on filter paper which was oxidized in a commercial sample oxidizer. The high temperatures generated by the combustion of the filter paper decomposed the Ba 14CO3 to BaO and 14CO2, the latter of which was trapped and prepared for liquid-scintillation counting by the sample oxidizer. Recoveries of 14C were 96%±4%. This method can be performed in minutes and is particularly applicable where large quantities of trapping solution are required for 14CO2 collection, because the Ba 14CO3 may be collected quantitatively on filter paper.

The effect of cecectomy on fecal bile acid and neutral steroid excretion of the rat

Abstract 1. 1. The quantitative and qualitative effects of cecectomy on fecal steroid excretion of rats were examined. 2. 2. Fecal steroid was measured by gas-liquid chromatography. 3. 3. The cecectomized rats were observed to mainly excrete bile acids and neutral steroids which had not undergone microbial modification. 4. 4. No difference was found in the total steroid excretion, indicating that decreased microbial dehydroxylation activity did not alter the steroid fecal excretion rate. 5. 5. Fecal β-glucuronidase activity was observed to decrease to 10% of its original activity following cecectomy.