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Biomedical subjects

J R Chipley

Publications and source records attributed to J R Chipley.

At least 37 records · Page 2Linked to original sources
PubMed1974

Further characterization of tissue distribution and metabolism of (14C)aflatoxin B1 in chickens.

The distribution and metabolism of [(14)C]aflatoxin B(1) in chicken tissues were further investigated. Previously dried and frozen ethyl acetate extracts of liver, heart, gizzard, breast, leg, blood, and fecal samples were obtained from either layer or broiler chickens fed subclinical levels of [(14)C]aflatoxin B(1). Treatment of these extracts with either carboxypeptidase A, leucine aminopeptidase, pepsin, or trypsin revealed that an average of 50% of the (14)C detected in the acetate extracts was a liberated peptide (or amino acid) conjugate of [(14)C]aflatoxin B(2a). When a prepared standard of B(2a) was made by incubation of B(1) with cold dilute aqueous HCl, the R(f) values and absorbance maxima were identical with those of the tissue extracts after enzymatic treatment.

Acetates↗
PubMed1973

Ochratoxins.

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Animals↗
PubMed1973

Tissue distribution and metabolism of aflatoxin B 1 - 14 C in Broiler chickens.

The effects of administering low levels of aflatoxin B(1)-(14)C by crop intubation daily for 14 days to broiler chickens were determined. Studies on the distribution of (14)C in the blood, selected organs, tissues, and excreta were conducted. No toxic effects were observed in broiler chickens during the 14 days of the experiment. The broiler chickens excreted 90.64% of the (14)C administered. Of the (14)C retained, 11.04, 9.83, 4.30, 12.52, 31.66, and 30.63% were detected in the blood, liver, heart, gizzard, breast, and leg, respectively. Chemical assay of those samples demonstrating radioactivity revealed that 81.2% of the radioactivity in these substrates was not extractable by classical extraction procedures while approximately 10% was extractable. Treatment of aqueous extracts for conjugated steroids by treatments with beta-glucuronidase revealed that 31.5% of the (14)C detected in the aqueous extract was a liberated glucuronide conjugate of aflatoxin M(1)-(14)C.

Aflatoxins↗
PubMed1971

Microbial flora of pecan meat.

Microorganisms found associated with commercially shelled pecan meats are numerous and varied. No bacteria and only two fungal microorganisms, Aspergillus clavatus and Tricothecium species, were found on aseptically shelled pecans.

Bacteria↗
PubMed1968

Survival of aerobic and anaerobic bacteria in chicken meat during freeze-dehydration, rehydration, and storage.

Total and anaerobic counts were ascertained on boneless, cooked, cubed, frozen chicken meat. We determined survival of aerobes and anaerobes in the natural flora after the meat was freeze-dehydrated and rehydrated at room temperature for 30 min and at 50, 85, and 100 C for 10 min. Total and anaerobic counts of bacteria in the rehydrated meat were established during storage of samples at 4, 22, and 37 C-until a spoilage odor was detected. Samples were also inoculated with Clostridium sporogenes and were dried and rehydrated at 100 C and stored at 37 C. Approximately 21% of the aerobes and 37% of the anaerobes survived drying and rehydration at room temperature. Many genera of aerobes, anaerobes, and facultative anaerobes survived drying and rehydration at 50 C; only sporeformers survived rehydration at 85 or 100 C. Low-temperature (4 C) storage of rehydrated meat produced ample shelf life (over 20 days), whereas storage at the higher temperature resulted in a shelf life of less than 30 hr. Approximately 81% of the C. sporogenes cells survived rehydration at 100 C and grew to over 10(7) cells within 40 hr. Our study presents additional data for adequate microbiological control in processing of freeze-dehydrated meat. Also, it points out the natural selection for sporeformers at high temperature of rehydration, stressing the need for consumer education in product handling for safety purposes.

Animals↗
PubMedDate not supplied

Interaction of aflatoxin B1 with bacterial DNA: possible relationship to bacteriophage induction in lysogenic Bacillus megaterium.

Studies were conducted to determine possible interactions between aflatoxin B1 and deoxyribonucleic acid (DNA) and induction of bacteriophage formation in lysogenic Bacillus megaterium NRRL-B-3695. At pH 7.4, the spectrophotometric characteristics of B1 with various concentrations of calf thymus DNA were altered with both a hypochromic shift and a shift of the wavelength for maximum absorbance of the toxin. Aflatoxin B1 apparently interacted with DNA as indicated by spectrophotometric analysis and ultrafiltration studies. Under alkaline conditions (pH 10.0), spectrophotometric characteristics of this interaction were altered from those observed at pH 7.4. Toxin incubated at pH 7.4 could induce bacteriophage formation but failed to do so at pH 10. Preincubation of toxin with calf thymus DNA did not block subsequent induction. It is proposed that a bacterial DNA-toxin interaction, involving an alkaline-labile bond of aflatoxin B1, is necessary to cause induction of bacteriophage formation in lysogenic B. megaterium.

Aflatoxin B1↗
PubMedDate not supplied

Effects of mixed-function oxidase and aflatoxin B1 on lysogenic and indicator strains of Bacillus subtilis.

The present study was conducted to determine the effects of metabolized aflatoxin B1 (via a mammalian liver mixed-function oxidase system) and native aflatoxin B1 upon induction of bacteriophage in Bacillus subtilis and growth of B. subtilis. A lysogenic strain of B. subtilis (BDS-1, phi 105) and an indicator strain of this species (DBS-1) were utilized in the present experiment. Lysogenic cultures were incubated for various lengths of time in the presence of either native or metabolized toxin, and plaque-forming units were determined. Identical experiments were conducted with the indicator strain and colony-forming units were determined. At a native toxin concentration of 25 micrograms/ml of medium, the maximum number of plaque-forming units was induced in lysogenic cells. However, when cells were incubated in the presence of aflatoxin B1 and mixed-function oxidase, neither plaque-forming units nor colony-forming units could be detected from lysogenic or indicator cells, respectively. This organism is apparently much more susceptible to inhibition of cellular replication than to lysis via bacteriophage induction. Thus, from the present study and from previously reported research, differences in susceptibility to native and metabolized aflatoxin B1 exist among species of Bacillus.

Aflatoxin B1↗