(1/105) Model ecosystem evaluation of the environmental impacts of the veterinary drugs phenothiazine, sulfamethazine, clopidol, and diethylstilbestrol.
Four veterinary drugs of dissimilar chemical structures were evaluated for environmental stability and penchant for bioaccumulation. The techniques used were (1) a model aquatic ecosystem (3 days) and (2) a model feedlot ecosystem (33 days) in which the drugs were introduced via the excreta of chicks or mice. The model feedlot ecosystem was supported by metabolism cage studies to determine the amount and the form of the drug excreted by the chicks or mice. Considerable quantities of all the drugs were excreted intact or as environmentally short-lived conjugates. Diethylstilbestrol (DES) and Clopidol were the most persistent molecules, but only DES bioaccumulated to any appreciable degree. Phenothiazine was very biodegradable; sulfamethazine was relatively biodegradable and only accumulated in the organisms to very low levels. Data from the aquatic model ecosystem demonstrated a good correlation between the partition coefficients of the drugs and their accumulation in the fish. (+info)
(2/105) N-acetylation of the heterocyclic amine batracylin by human liver.
Batracylin (8-aminoisoindolo[1,2-b]quinazolin-12(10 H)-one; BAT) is a heterocyclic amine that exhibits antitumor activity in a number of in vivo and in vitro models. The acetyl product has been implicated in BAT toxicity in animals, cells, and bacteria. The ability of human N-acetyltransferase (NAT) to form this product was investigated. Nine human liver samples were analyzed for NAT1 and NAT2 genotypes. Seven of the samples possessed at least one NAT1*4 allele. Three samples contained one or more NAT2*4 allele and were classified as rapid acetylators. The remaining six had two alleles associated with the slow phenotype. NAT activities were evaluated with BAT, sulfamethazine (SMZ), a preferential substrate for human NAT2, and p-aminobenzoic acid, a substrate for NAT1. BAT activities in the nine donor samples ranged from 14.9 to 0.56 nmol/min/mg. The mean apparent K(m) values in rapid acetylators for BAT, SMZ, and p-aminobenzoic acid were 6.59 +/- 3.21, 278 +/- 69.4, and 31.2 +/- 12.5 microM, respectively. The apparent K(m) values for slow acetylators did not differ from the rapid acetylator phenotype. However, a significant difference in the apparent V(max) for BAT and SMZ was observed between rapid and slow acetylators. Comparing the apparent intrinsic clearance (V(max)/K(m)) for BAT and SMZ, a significant correlation (r(2) = 0.97, p <.001) was observed. These data demonstrate that BAT N-acetylation is similar to SMZ, and suggests that BAT is a preferential substrate for human NAT2. Thus, rapid acetylators would be more likely to develop toxicity when exposed to this drug. (+info)
(3/105) N-Acetylation of paraphenylenediamine in human skin and keratinocytes.
Skin is the major target of allergic reactions to paraphenylenediamine (PPD). Such small molecules require activation to become immunogenic. The balance between activation and/or detoxification processes is critical for immunogenic potentials of compounds. Therefore, we investigated N-acetylation (NAT) capacities of human skin for PPD to gain a better understanding of its mechanisms of action. PPD is acetylated to monoacetyl-PPD (MAPPD), which in turn is acetylated to N,N'-diacetyl-PPD (DAPPD). This was found using cytosolic fractions from human skin (n = 9) and cultured normal human epidermal keratinocytes (n = 7). The cutaneous activities for MAPPD formation ranged from 0.41 to 3.68 nmol/mg/min (9-fold variation) and DAPPD formation from 0.65 to 3.25 nmol/mg protein/min (5-fold), respectively. Similar results were obtained with keratinocytes. NAT activities toward both substrates, PPD and MAPPD, were correlated in keratinocytes (r = 0.930), suggesting that the reactions were catalyzed by the same enzyme. Formation of MAPPD and DAPPD was competitively inhibited in the presence of p-aminobenzoic acid (300 microM), a typical NAT1 substrate, but not by sulfamethazine. These kinetic characteristics suggest that the acetylation of PPD in human skin and keratinocytes is predominantly attributable to the polymorphic NAT1, although both mRNAs (NAT1 and NAT2) are synthesized in human skin and keratinocytes. The metabolism of PPD by NAT1 in human skin and keratinocytes as well as the virtual absence of NAT2 activity may have important toxicological implications. In the case of PPD, our results emphasize that N-acetylation status may be a susceptibility factor for the development of an allergy to PPD. (+info)
(4/105) Effect of feed intake on antimicrobially induced increases in porcine serum insulin-like growth factor I.
This study was conducted to determine whether an antimicrobially induced (ASP-250) increase in serum IGF-I was the result of differences in feed intake. Serum IGF-I concentrations were measured in crossbred pigs that were fed a control diet or a diet supplemented with ASP-250 either for ad libitum consumption or limited to 85% of the control pigs' consumption. The pigs that consumed either diet ad libitum, control or ASP-250, consumed similar quantities of feed. The ASP-250 ad libitum-intake pigs had serum IGF-I concentrations that were greater (P<.01) than those of their ad libitum-intake control littermates. Similarly, the ASP-250 limit-fed pigs had serum IGF-I concentrations that were greater (P<.01) than those of the controls. Although the serum IGF-I concentrations of pigs fed the ASP-250-supplemented diet for ad libitum intake were greater than the serum IGF-I concentrations of the pigs limit-fed the ASP-250-supplemented diet, the differences were not significant (P<.08). The ASP-250-fed pigs had higher serum IGF binding protein (BP)-3 concentrations than did their control littermates (P<.003). A time course of antimicrobially induced alterations in serum IGF-I concentrations revealed that the effect of increased serum IGF-I levels in ASP-250-supplemented pigs (P<.02) was observed within 4 d and was maintained throughout the 4-wk study. These findings show that feed intake is not responsible for the increase in serum IGF-I observed with ASP-250 supplementation. Additionally, the antimicrobially induced increase in serum IGF-I concentrations occurs within a few days after initiation of the treatment. (+info)
(5/105) Direct competitive enzyme-linked immunosorbent assay for sulfamethazine.
A direct competitive enzyme-linked immunosorbent assay (ELISA) for screening sulfamethazine (SMZ) in pork tissues was developed. The assay was made with the affinity-purified polyclonal antibody-coated microtiter plate. A cross reactivity of IgG was observed at 3.5 microg/g of sulfamerazine among nine kinds of sulfonamide tested. Pork tissues fortified with SMZ was mixed with octadecyl silica (C18), and extracted with dichloromethane. The extracted SMZ was measured by homemade ELISA, commercial ELISA, and HPLC. The results were correlated (r=0.993, p<0.01). The homemade ELISA was sensitive to determine SMZ at the maximum residue level (MRL) as commercial one. During stability test of the IgG coated microtiter plate performed at 40 degrees C for 14 days, no difference in sensitivity was observed. We developed homemade ELISA with a detection limit of 10 ng of SMZ per g of pork tissues, and it could be used to screen SMZ in pork tissues. (+info)
(6/105) Luminous vibriosis in rock lobster Jasus verreauxi (Decapoda: Palinuridae) phyllosoma larvae associated with infection by Vibrio harveyi.
Studies were conducted to determine the cause of outbreaks of luminous vibriosis in phyllosoma larvae of the packhorse rock lobster Jasus verreauxi reared in an experimental culture facility. On 2 separate occasions mortalities of up to 75% over a period of 4 wk were observed in 4th to 5th and 8th to 10th instar phyllosomas at water temperatures of 20 and 23 degrees C, respectively. Affected larvae became opaque, exhibited small red spots throughout the body and pereiopods, and were faintly luminous when viewed in the dark. Histopathology showed that the gut and hepatopancreas tubules of moribund phyllosomas contained massive bacterial plaques. The hepatopancreas tubules of moribund larvae were atrophic and some contained necrotic cells sloughed into the lumen. Dense, pure cultures of a bacterium identified as Vibrio harveyi were isolated from moribund larvae. The disease syndrome was reproduced by in vivo challenge and V. harveyi was successfully reisolated from diseased larvae after apparently healthy larvae were exposed by immersion to baths of more than 10(4) V. harveyi ml(-1) at 24 degrees C. Injured larvae were more susceptible to infection than were healthy larvae. Survival of larvae experimentally and naturally exposed to V. harveyi was improved when antibiotics were administered via bath exposures. (+info)
(7/105) Preparation of superior thin-layer chromatograms for quantitative in situ densitometry by nonequilibrated development. I. Trisulfapyrimidines: sulfadiazine, sulfamerazine, and sulfamethazine.
A method of obtaining controlled nonequilibrated horizontal plate development by employing a developing system open to room atmosphere is described and compared with other plate-developing techniques. Nonequilibrated plate development produced spot configurations with the precise physical outline and densitometric distribution needed for optical scanning. (+info)
(8/105) Peripheral blood lymphocyte response to phytomitogens in systemic lupus erythematosus.
The response of peripheral blood lymphocytes to the phytomitogens, PHA, Con A, and PWM, was evaluated in 30 SLE patients and in 30 age, sex, and race-matched controls using dose and time responses. The proliferative response to the three phytomitogens was not depressed in this group of subacute and chronic SLE patients. Active lupus nephritis and a slow acetylator phenotype were associated with a decreased lymphocyte response. The incidence of a slow acetylator phenotype in spontaneous SLE was 68%. In interpreting the lymphocyte response to phytomitogens, the importance of a clear definition of the SLE group under study, the activity of the disease, and treatment status are emphasized. (+info)