Two angular dioxygenases contribute to the metabolic versatility of dibenzofuran-degrading Rhodococcus sp. strain HA01.

Rhodococcus sp. strain HA01, isolated through its ability to utilize dibenzofuran (DBF) as the sole carbon and energy source, was also capable, albeit with low activity, of transforming dibenzo-p-dioxin (DD). This strain could also transform 3-chlorodibenzofuran (3CDBF), mainly by angular oxygenation at the ether bond-carrying carbon (the angular position) and an adjacent carbon atom, to 4-chlorosalicylate as the end product. Similarly, 2-chlorodibenzofuran (2CDBF) was transformed to 5-chlorosalicylate. However, lateral oxygenation at the 3,4-positions was also observed and yielded the novel product 2-chloro-3,4-dihydro-3,4-dihydroxydibenzofuran. Two gene clusters encoding enzymes for angular oxygenation (dfdA1A2A3A4 and dbfA1A2) were isolated, and expression of both was observed during growth on DBF. Heterologous expression revealed that both oxygenase systems catalyze angular oxygenation of DBF and DD but exhibited complementary substrate specificity with respect to CDBF transformation. While DfdA1A2A3A4 oxygenase, with high similarity to DfdA1A2A3A4 oxygenase from Terrabacter sp. strain YK3, transforms 3CDBF by angular dioxygenation at a rate of 29% +/- 4% that of DBF, 2CDBF was not transformed. In contrast, DbfA1A2 oxygenase, with high similarity to the DbfA1A2 oxygenase from Terrabacter sp. strain DBF63, exhibited complementary activity with angular oxygenase activity against 2CDBF but negligible activity against 3CDBF. Thus, Rhodococcus sp. strain HA01 constitutes the first described example of a bacterial strain where coexpression of two angular dioxygenases was observed. Such complementary activity allows for the efficient transformation of chlorinated DBFs.

Molecular detection and diversity of novel diterpenoid dioxygenase DitA1 genes from proteobacterial strains and soil samples.

Resin acids are tricyclic diterpenoids naturally synthesized by trees that are released from wood during pulping processes. Using a newly designed primer set, genes similar to that encoding the DitA1 catalytic alpha-subunit of the diterpenoid dioxygenase, a key enzyme in abietane resin acid degradation by Pseudomonas abietaniphila BKME-9, could be amplified from different Pseudomonas strains, whereas ditA1 gene sequence types representing distinct branches in the evolutionary tree were amplified from Burkholderia and Cupriavidus isolates. All isolates harbouring a ditA1-homologue were capable of growth on dehydroabietic acid as the sole source of carbon and energy and reverse transcription polymerase chain reaction analysis in three strains confirmed that ditA1 was expressed constitutively or in response to DhA, demonstrating its involvement in DhA-degradation. Evolutionary analyses indicate that gyrB (as a phylogenetic marker) and ditA1 genes have coevolved under purifying selection from their ancestral variants present in the most recent common ancestor of the genera Pseudomonas, Cupriavidus and Burkholderia. A polymerase chain reaction-single-strand conformation poylmorphism fingerprinting method was established to monitor the diversity of ditA1 genes in environmental samples. The molecular fingerprints indicated the presence ofa broad, previously unrecognized diversity of diterpenoid dioxygenase genes in soils, and suggest that other bacterial phyla may also harbour the genetic potential for DhA-degradation.

Lincomycin dose response for treatment of necrotic enteritis in broilers.

A dose response study was conducted to determine the appropriate (optimal) lincomycin concentration in drinking water for the treatment of necrotic enteritis (NE) in broilers. The study was replicated twice over time using a total of 2,895 broilers. Birds were raised in a facility containing a built-up litter from a source that experienced NE. They were commingled from 1 day of age until NE was observed. Lincomycin was mixed in drinking water at a rate of 0, .528, 2.114, 8.454, or 33.818 mg/liter for a period of 7 days. The study was terminated 3 weeks after initiation of therapy. Necrotic enteritis was diagnosed by mortality and pathological findings. The data on mortality were analyzed statistically using analysis of variance procedures. The Walker-Carmer technique was applied to estimate the appropriate lincomycin concentration. Lincomycin was effective for the treatment of NE in broilers at concentrations of greater than or equal to 2.114 mg/liter of drinking water. The minimal effective dose that would achieve maximal treatment response (optimal dose) against NE in broilers was estimated to be 16.9 mg lincomycin/liter of drinking water.

Therapeutic effect of optimal lincomycin concentration in drinking water on necrotic enteritis in broilers.

The efficacy of 16.9 mg lincomycin/liter of drinking water was evaluated for the treatment of necrotic enteritis (NE) in 743 broiler-type chickens. Birds were raised in a facility containing a built-up litter obtained from a source that experienced NE. They were commingled from 1 day of age until NE was observed. Two groups of 6 pens each were given 0 or 16.9 mg lincomycin/liter of drinking water. Water medication was offered fresh daily for 7 days and the study was terminated 3 weeks after initiation of therapy. The susceptibility of Clostridium perfringens to lincomycin was determined in vitro. The test organism was susceptible to lincomycin as reflected by minimal inhibitory concentration and minimal lethal concentration of .156 microgram/ml. Mortality attributed to NE was 0% in lincomycin treated birds and 14% in nonmedicated control birds (P less than .01). Lincomycin water medication was highly effective for the treatment of NE in broilers.

Efficacy of lincomycin-spectinomycin water medication on Mycoplasma meleagridis airsacculitis in commercially reared turkey poults.

A field trial was conducted to compare the efficacy of a combination of the drugs lincomycin and spectinomycin (LS) with Tylan (tylosin, T) against Mycoplasma meleagridis (MM) airsacculitis in 50,320 commercially reared turkey poults in Ohio. Both drugs were administered at 2 g per gallon of drinking water for the first 5 days of life. The poults were allotted randomly to two treatment groups with 8 or 5 replicates each. Initially, 250 poults were weighed, necropsied, and examined microbiologically and grossly for airsacculitis. At 3 weeks of age, 33 poults from each replicate were randomly selected, necropsied, and examined for airsacculitis. The data indicate that LS is superior to T as an aid in the control of MM airsacculitis in poults, as reflected by fewer air-sac lesions and greater improvement in weight gain (P less than 0.05).

Comparison between circulating interferon and drug levels following administration of 2-amino-5-bromo-6-phenyl-4(3H)-pyrimidinone (ABPP) to different animal species.

Using a high-performance liquid chromatographic assay, these studies attempted to correlate circulating levels of 2-amino-5-bromo-6-phenyl-4(3H)-pyrimidinone (ABPP) with the serum interferon response induced in mice, cats, dogs, cattle, and rabbits. The order of greatest sensitivity for interferon induction by ABPP was mice greater than cats greater than dogs greater than cattle greater than rabbits. Experiments to date indicate that the circulating drug levels associated with a detectable interferon response were 10-15 microgram/ml (mice), 15-30 micrograms/ml (cats and dogs), and 30-50 micrograms/ml (cattle). Whereas rabbits produced large amounts (greater than 10(4) units/ml) of interferon when induced with Newcastle disease virus, we could not demonstrate unequivocally that rabbits were induced by ABPP even when circulating drug levels reached 50 micrograms/ml, or greater. We also observed differences in the pharmacokinetics of ABPP in the different species which may contribute to the differences described for the interferon responses. The data point out the need for cautious selection of animal models for preclinical efficacy evaluation and cautious extrapolation of data from preclinical studies to eventual clinical evaluation.

High performance reversed phase chromatography of cholesterol and cholesteryl esters of human plasma lipoproteins.

Cholesterol and cholesteryl esters were separated according to their carbon number and number of double bonds by high performance reversed-phase chromatography (HPRC) using acetonitrile/chloroform/methanol (1:1:1, v/v) as a mobile phase. It was found that within the same equivalent carbon number (ECN) category, cholesteryl esters with the highest number of double bonds eluted ahead of those with a lower number of double bonds, and with the cis isomers eluting ahead of their trans partners. Thus, cholesteryl oleate (C27-18:1c) elutes ahead of cholesteryl palmitate (C27-16:0) and ahead of cholesteryl elaidate (C27-18:1t). Human lipoprotein, as well as rat liver cholesteryl esters, were separated using this technique.

Therapeutic effects of parenteral administration of lincomycin on experimentally transmitted swine dysentery.

The therapeutic effects of 2 dose levels of lincomycin and a reference drug (tylosin) were compared in 80 growing pigs with experimentally transmitted swine dysentery (SD). The pigs were allotted equally to 4 groups. Treatment was initiated 5 days after pigs were exposed to SD. Lincomycin was administered IM at doses of 11.0 or 4.4 mg/kg of body weight once daily for 3 to 7 days. Tylosin was injected IM at a dose of 8.8 mg/kg once daily for 3 days (highest recommended dose). The control (nontreated) infected pigs were not given the drug. The effects was terminated 22 days after exposure to SD. The effects were measured in terms of mortality, survival, physical activity, performance, and necroscopy findings. The 2 drugs reduced the clinical signs of SD. Pigs treated with either dose of lincomycin had a better treatment response than did pigs treated with tylosin, as evidenced by less mortality, longer survival time, and greater feed intake (P = 0.05). In addition, pigs treated with the larger dose of lincomycin, 11.0 mg/kg, had better treatment responses in 12 of the 14 measured criteria than did pigs treated with tylosin. Also, these pigs treated with the larger lincomycin dose had better treatment responses tha did the pigs treated wih the smaller dose of lincomycin, 4.4 mg/kg, as evidenced by dysentery, fecal consistency, physically active and intermediately active pig days, body weight gain, and feed intake.

Efficacy of Linco-Spectin medication on mycoplasma meleagridis airsacculitis in turkey poults.

The efficacy of Linco-Spectin (LS) water medication was determined against Mycoplasma meleagridis (MM) airsacculitis in turkey poults under controlled conditions. The poults were obtained from commercial flocks naturally infected with MM. Water medication was given for the first five days of life. In Georgia and Ohio, LS was given at 0, 1, 2, and 4 g per gallon of drinking water. In California and Minnesota, LS was administered at 0 and 2 g per gallon of drinking water. At three weeks old, the birds were weighed individually and examined serologically, culturally, and grossly for MM airsacculitis. LS at 2 g activity per gallon of drinking water was beneficial in controlling MM airsacculitis in all four trials.

Effect of a single injection of lincomycin, spectinomycin, and linco-spectin on early chick mortality caused by Escherichia coli and Staphylococcus aureus.

The efficacies of lincomycin (L) and spectinomycin (S), alone and in various combinations (L/S), were determined against Escherichia coli (EC) and Staphylococcus aureus (SA) of avian origin, both in vitro and in vivo. L contributed significantly to L/S activity against SA, while S contributed significantly to L/S activity against EC, and L/S (2.5 mg L + 5.0 mg S) was more effective than either L or S against SA and EC. The suggested optimum dose for controlling early chick mortality caused by SA and EC is 2.5/5.0 mg of L/S per chick.

Therapeutic effects of various concentrations of lincomycin in drinking water on experimentally transmitted swine dysentery.

Three experimental studies were conducted in 232 growing pigs (8 to 12 weeks old) to evaluate the therapeutic effects of various concentrations of lincomycin in drinking water, against swine dysentery experimentally transmitted, by oral inoculation or by contact-commingling exposure. Four or 5 concentrations of lincomycin were used in each experiment (132, 66, 33, 16.5 or 0.0 mg/L of drinking water). Medication was initiated 7 to days after exposure and was continued for 6 to 10 days. Both methods of exposure were capable of transmitting the disease successfully. A more marked dose response was noticed in pigs inoculated orally than in pigs that were exposed by contact. All concentrations of lincomycin were effective for the treatment of swine dysentery by oral or by contact exposure. At the smaller concentration of 16.5 mg/L of drinking water, lincomycin was less effective for treating the disease than it was at greater concentrations. The suggested optimal concentration was 33 mg of lincomycin/L of drinking water for the treatment of swine dysentery.

Efficacy of Linco-Spectin water medication on Mycoplasma synoviae Airsacculitis in broilers.

Three trials were conducted to evaluate the efficacy of Linco-Spectin (LS) water medication on Mycoplasma synoviae (MS) air-sacculitis in broilers under controlled experimental conditions. Day-old chicks were vaccinated against infectious bronchitis and Newcastle disease virus and exposed to a broth culture of MS by the respiratory route. In each trial, one-half of the flock was treated with 2 g of LS per gallon of drinking water for the first five days of life, and the other half was kept as a control. At two and eight weeks postinoculation (PI) birds were weighted individually and examined serologically, culturally, and grossly for MS airsacculitis. Linco-Spectin water medication was effective in controlling MS airsacculitis in broilers.

Efficacy of lincomycin and spectinomycin on canine pathogens.

Lincomycin (L), spectinomycin (S), and both (L-S) were evaluated in vitro and vivo against canine pathogens. In vitro, a wider spectrum of antimicrobial activity was achieved with L-S than with either L or S. The therapeutic effects of the antibiotics were investigated in 36 dogs inoculated with a mixture of the microbal agents. Tonsillitis, conjunctivitis, laryngitis, abscess formation, and necropsy findings were measured. The L-S combination was effective for the treatment of tonsillitis, conjunctivitis, laryngitis, and pneumonia in dogs.

Activity of penicillin and novobiocin against bovine mastitis pathogens.

Penicillin (P), novobiocin (N), and both (P-N) were evaluated in vitro against 143 clinical isolates of bovine mastitis, including, Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, and Streptococcus uberis. Greater antistaphylococcal activities were demonstrated with N alone and P-N than with P alone. Streptococcus spp were more susceptible to P alone than to N alone, and the effectiveness of P-N corresponded with that of P alone. In vitro, P-N had a wider spectrum of antibacterial activity than did either P or N. Similar results were also obtained in vivo, using the mouse protection test. The P-N gave a greater protection rate in mice experimentally infected with S aureus and Str agalactiae than did P or N.

Therapeutic effect of lincomycin and spectinomycin water medication on swine dysentery.

The therapeutic effects of various water medications on swine dysentery were determined in 223 pigs under controlled conditions. Carrier pigs were mixed with test animals until the disease was established. Lincomycin (22 mg/liter), spectinomycin (44 mg/liter) alone and lincomycin and spectinomycin in combination (66 mg/liter) and sodium arsanilate (161 mg/liter) in drinking water for seven days were the drugs evaluated. Negative and positive controls were also included. The experiment was terminated 41 to 43 days after initial medication. Mortality, mean value for stool consistency, incidence of dysenteric days and gross lesions of swine dysentery were the parameters measured for each treatment group.The lincomycin-spectinomycin water medication was effective for the treatment of swine dysentery. Pigs treated with lincomycin-spectinomycin had a higher survival rate, a lower incidence of dysenteric days and fewer gross lesions of swine dysentery than pigs treated with sodium arsanilate, lincomycin or spectinomycin alone or the infected controls (P < 0.05).

In vitro activity of lincomycin and spectinomycin against serotypes of avian mycoplasma.

Twenty strains of avian mycoplasma, representing 12 serotypes, were tested in vitro for their susceptibility to the action of lincomycin and spectinomycin alone and in combination. They varied in their sensitivity pattern. The ranges of minimal inhibitory concentration were 1 to 20 mug/ml for lincomycin or spectinomycin alone and 0.5/1 to 3/6 mug/ml for the lincomycin and spectinomycin combination. The ranges of minimal lethal concentration were greater with either single antibiotic than with the antibiotic combination. The amount of each antibiotic required to achieve mycoplasmacidal action of the relatively resistant strains was less with the antibiotic combination than with the single antibiotics.