Pharmacokinetics of florfenicol, thiamphenicol, and chloramphenicol in turkeys.

The pharmacokinetics of florfenicol (FF), thiamphenicol (TP) and chloramphenicol (CP) after single intravenous (i.v.) or oral (p.o.) administration was studied in an independent cross-over study in broiler turkeys. All the fenicol antibiotics were administered at a dose of 30 mg/kg b.w. and their concentrations in plasma samples were assayed using the same validated high-performance liquid chromatography method. Pharmacokinetic parameters were calculated by a noncompartmental method. The kinetic profiles of the compounds were compared with the results of the structure-activity relationship. According to the proposed mathematical description, no differences in plasma clearance values for the studied antibiotics were observed. The mean residence time values of FF, TF, and CP after i.v. injection were 3.37+/-0.63, 2.43+/-0.29, and 2.12+/-0.21 h, respectively. The mean values of Varea for FF (1.39+/-0.31 L/kg) and TP (1.31+/-0.19 L/kg) were similar, but significantly different from that of CP (1.04+/-0.12 L/kg). The bioavailabilities of FF, TP, and CP after oral administration were 82%, 69%, and 45%, respectively. Differences in the bioavailability values of the compared fenicol antibiotics correspond to the ratio of the apolar/polar surface areas of their particles.

Effects of thymomimetic drugs and zinc supplementation on the cellular immune response in hydrocortisone-suppressed mice.

The studies were carried out on Balb/c mice (5-6 weeks of age) exposed to immunosuppression by a single intraperitoneal dose (125 mg/kg) of hydrocortisone. Prior to hydrocortisone injection the mice were treated with diethyldithiocarbamate (DTC) intra-peritoneally at a dose of 20 mg/kg, five times at 48 h intervals or calf thymus extract (TFX) at a dose of 10 mg/kg, 10 times at 24 h intervals. The two drugs were used per se or in zinc ions interactions, by adding zinc ions (as sulphate salt) to drinking water at a dose of 72 microg/mouse per day. The results obtained in the study show that hydrocortisone injection drastically decreases the number of thymocytes and splenocytes, which is also accompanied by a decreasing weight ratio of the thymus and spleen. The decreasing number of thymic and spleen cells corresponds to a decreasing percentage of CD4+, CD8+ and CD19+ splenocytes and double positive CD4+CD8+ thymocytes. Changes in the number of thymic cells affect their activity, which is expressed in a decreased proliferative response of thymocytes stimulated in vitro with concanavalin A (Con A) and phytohaemagglutinin (PHA). It has also been found that a single hydrocortisone dose decreases interleukin (IL)-1 production by murine intraperitoneal macrophages stimulated in vitro with lipopolysaccharide (LPS) from Escherichia coli. TFX or DTC counteract hydrocortisone-induced immunosuppression, which is expressed in partial normalization of the total number of thymic and spleen cells, accelerated regeneration of the two lymphatic organs, shorter suppressive action of hydrocortisone on the percentage of CD4+, CD8+ splenocytes and double positive (CD4+CD8+) and CD4+ thymocytes. Furthermore, total counteraction against the suppressive action of hydrocortisone to proliferative activity of thymocytes stimulated in vitro with Con A and PHA was observed. TFX administered prior to hydrocortisone injection partially prevented the suppressive action of the drug on IL-1 production by intraperitoneal macrophages, but such an effect was not observed with DTC. The immunorestorative effect of TFX and DTC was augmented by zinc supplementation. The results obtained in the study show that neither TFX nor DTC administration per se and in interaction with zinc supplementation were able to change the suppressive effect of hydrocortisone on the percentage of B splenocytes (CD19+ cells).

Effects of lysozyme dimer on humoral response to sheep erythrocytes in non-treated and cyclophosphamide-immunosuppressed mice.

The effects of lysozyme dimer on humoral response to sheep erythrocytes (SRBC) and restoration of the response impaired by a single cyclophosphamide dose (200 mg/kg) were tested on mice. The effect of lysozyme dimer on the humoral response to SRBC in non-treated with cyclophosphamide mice was determined in relation to doses (0.2, 2, 20 or 200 micrograms/kg) and the time of the drug administration with respect to the antigen before or after SRBC immunization. Moreover, the effect of lysozyme dimer on the humoral response in cyclophosphamide-treated mice was studied depending on the dose applied and time of exposure to the drug in relation to SRBC. It has been found that lysozyme dimer potentiates the humoral response to SRBC in mice, resulting in an increased number of splenocytes producing haemolytic antibodies (PFC) and the total and 2-mercaptoethanol resistant level of anti-SRBC antibodies. A single exposure to lysozyme dimer gave the strongest stimulating action on SRBC when the doses of 2 or 20 micrograms/kg were administered 2 h prior to the antigen. The potentiating effect of the drug was reduced when it was administered 24 h before the antigen and also when single doses were as high as 200 micrograms/kg and as low as 2 micrograms/kg. Exposure to four doses of lysozyme dimer at 24 h intervals was more activating than a single injection. A strong potentiating effect on the specific response to SRBC was noted after four injections of lysozyme dimer at doses from 0.2 to 20 micrograms/kg. The effect of the drug did not depend on the time of exposure to the antigen. It has also been found that lysozyme dimer significantly reduces the suppressive effect of a high cyclophosphamide dose (200 mg/kg) on the humoral response of SRBC-immunized mice. The protective action of lysozyme dimer was dose- and time-dependent. The strongest protection was observed after three doses of 20 micrograms/kg administered prior to pharmacological immunosuppression. Reduction in the dose to 2 micrograms/kg and shorter treatment resulted in reduced protective effects. We have also found that the protective action of three doses of lysozyme dimer (2 or 20 micrograms/kg each) administered between cyclophosphamide injection and the antigen, or after antigen administration is weaker than such a treatment prior to cyclophosphamide immunosuppression.

Modulation of secondary antibody response in SRBC-immunized mice by lysozyme dimer.

The effect of lysozyme dimer (20 micrograms/kg) injected i.p. once or four times to sheep erythrocytes-immunized mice on the secondary humoral response was studied with respect to the time of exposure to the drug in relation to priming and challenge. It has been found that lysozyme dimer potentiates secondary humoral response to SRBC; as a result, the number of splenocytes producing hemolytic anti-SRBC antibodies (PFC) and anti-SRBC hemagglutinin titers, especially 2-mercaptoethanol resistant increases provided that the drug is administered after the challenge. Lysozyme dimer (both a single dose and four times' exposure to the drug) administered after priming does not affect secondary humoral response of SRBC-immunized mice.

Effect of DTC on humoral response of SRBC-immunized mice exposed to restraint stress. Comparison with calf thymus extract.

The studies were conducted on Balb/c mice exposed to restraint stress twice for 12 h at 24 h intervals. Some of the experimental mice were immunized i.p. with sheep red blood cells (SRBC). The antigen was injected before the first exposure of the mice to restraint stress, or immediately after the second loading was ended. Sodium diethyldithiocarbamate (DTC) at a dose of 20 mg/kg or calf thymus extract (TFX) at a dose of 10 mg/kg were injected i.p. four times at 24 h intervals, before or after the exposure to restraint stress. In our experiment restraint stress drastically reduced the number of thymocytes and splenocytes as well as the weight ratio of the thymus and spleen and the changes sustained for 10 days of the observation. Besides, humoral response of the restrained mice to SRBC was deteriorated, as the number of plaque forming cells (PFC) and anti-SRBC antibody titers (total and 2-mercaptoethanol resistant) decreased. The suppressive action of the stress on humoral response was weaker when the antigen injection preceded the first exposure of mice to restraint stress as compared with that observed when antigen stimulation took place immediately after the exposure of mice to stress. It has been found that DTC and TFX administered to mice either before or after the exposure to restraint stress effectively inhibit stress-induced immunosupression. The protective or immunomodulating action of the two drugs is expressed in accelerated and enhanced recovery of the spleen and thymus and in total or partial restoration of the humoral response to thymus-dependent antigen. TFX, administered after the exposure of mice to restraint stress, proves to have a stronger protective and reconstructive impact on thymus, while DTC has a stronger restoring effect on the humoral response dependent on effector T lymphocytes. DTC administered immediately after the exposure of mice to restraint stress results in total restoration of humoral response to SRBC.

Modulating effect of sodium diethyldithiocarbamate on neutrophils in normal, febrile and cold-stressed rabbits.

The studies were conducted on normal, febrile and cold-stressed rabbits. Fever was induced by a single intravenous injection of 1 micrograms/kg of E. coli lipopolysaccharide (LPS). The animals were submerged in ice-water for 20 s and then were kept at -15 degrees C for approx. 8 min., until their body temperature dropped by 3 degrees C. Sodium diethyldithiocarbamate (DTC) was injected i.v. to normal, febrile and cold-stressed rabbits, in a single dose of 2 or 20 mg/kg. The effect of DTC on body temperature, the number of neutrophils in blood, phagocytic activity of neutrophils and their ability to reduce nitroblue tetrazolium (NBT) were evaluated. It was found that DTC administered in a dose of 2 or 20 mg/kg did not affect the body temperature of rabbits. In normal rabbits, DTC did not change the number of neutrophils, but increased their phagocytic activity and ability to reduce NBT. In febrile rabbits, DTC depending on the dose, shortened the stimulating effect of LPS on neutrophil ability to reduce NBT but enhanced and prolonged the effect of pyrogen on neutrophil phagocytic activity. The rabbits treated with DTC prior to hypothermia exhibited shorter neutrophilia resulting from cold stress. In addition, DTC administered to the rabbits before their exposure to cold stress proved to be a partial or even total protection against the decrease in NBT reducing ability and phagocytic activity of blood neutrophils.

Effect of mechlorethamine on SRBC-induced secondary antibody response in mice.

The effect of low-dose mechlorethamine (5 micrograms/kg) on secondary humoral response to sheep red blood cells (SRBC), depending on time of exposure to the drug in relation to priming and challenge was studied in Balb/c mice. It was found that mechlorethamine in a dose of 5 micrograms/kg stimulated primary humoral response to SRBC resulting in the increased number of the plaque forming cells (PFC) and hemagglutinin titre (19S + 7S). However, this effect waned 10 days after immunization. On the other hand, the same mechlorethamine dose potentiated secondary humoral response to SRBC and increased the number of PFC and anti-SRBC hemagglutinin titres (notably 7S), which was due to the challenging antigenic stimulus. In each immunization, mechlorethamine administration prolonged the potentiating effect of the drug on anti-SRBC hemagglutinin titre. When mechlorethamine was administered to the mice only after priming, the number of PFC increased, but anti-SRBC hemagglutinin titre (7S) remained unchanged. This was likely due to the fact that mechlorethamine administered after priming increases the number of long-lived lymphocytes B, which in turn affect secondary humoral response.

Effects of levamisole, DTC and low-dose mechlorethamine on humoral response of SRBC-immunized rabbits exposed to cold stress.

The experiments were carried out on normothermal rabbits and rabbits exposed to cold stress (hypothermia). The animals of the latter group were submerged in ice-water for 20 s and then placed in a freezer at -15 degrees C for 8 min until their body temperature dropped by 3 degrees C. Both the normothermal and hypothermal rabbits were immunized i.p. with 3 ml of 10% sheep red blood cells (SRBC). Levamisole (2 mg/kg), DTC (sodium diethyldithiocarbamate, 20 mg/kg) or mechlorethamine (mustine; 5 micrograms/kg) were injected i.v. three times at 24-h intervals. The number of PFC, total (19S + 7S) and 2-mercapthoethanol resistant (7S) serum haemagglutination titres were determined. It was found that, in normothermal rabbits, all three agents potentiated the number of plaque-forming cells (PFC); the impact of DTC was the strongest, while the weakest influence was observed for mechlorethamine. Furthermore, DTC increased anti-SRBC haemagglutinin titre, whereas mechlorethamine did not. Levamisole, on the other hand, reduced total serum haemagglutinin titre. Cold stress reduced humoral response to SRBC, which was reflected in the decreased number of PFC and serum haemagglutination titres (19S + 7S and 7S). Each agent showed a different way of action. Pretreatment with DTC prevented the immunosuppression caused by cold stress, while levamisole and mechlorethamine only reduced the immunosuppressive effect.

The influence of long-term administration of Tolpa Peat Preparation on immune reactivity in mice. III. The effect on primary humoral response to sheep erythrocytes.

Tolpa Peat Preparation (TPP) was administered to mice in daily doses of 1, 10 and 50 mg.kg-1 for 3, 5, 7, 9 or 12 consecutive weeks. After each of the above mentioned periods the primary response to sheep erythrocytes (SRBC) was examined by determination of the percentage of splenocytes forming E rosettes, the number of splenocytes producing anti-SRBC haemolysins of 19S and 7S type, and the level of serum haemagglutinins to SRBC (19S + 7S and 7S types). The effect of enhanced humoral response by TPP was observed in mice immunized with SRBC. This effect depended, first of all on TPP does but also on the duration of time TPP administration. The stimulating effect on the humoral response occurred after the daily dose of 1 mg.kg-1 during 12 weeks. On the other hand, the daily doses of 10 or 50 times higher enhanced the humoral response only during the first 5-7 weeks of TPP administration. Longer administration of TPP in these doses caused disappearance of this effect or reduction of the response to SRBC.

The dose-dependent effect of Tolpa Peat Preparation on the humoral response of mice immunized with sheep erythrocytes.

The Balb/c strain mice were immunized by single intraperitoneal administration of 0.2 cm3 of 10% sheep erythrocyte suspension (SRBC). Tolpa Peat Preparation (TPP) used in the study was a peat-derived substance obtained in prof. St. Tolpa's laboratory. It was given to mice intraperitoneally, 4 times at 24-hour intervals. The first dose was administered 2 hours before immunization. Testing was performed with the following doses: 0.5, 2.5, 5, 10, 25, 50, 100 and 250 mg/kg. The determinations comprised the number of spleen cells producing anti-SRBC haemolysins, the level of serum haemagglutinins to SRBC (19S+7S and 7S types) and the percentage of splenocytes forming spontaneous E-rosettes. It was found that the effect of TPP on these immunologic parameters of the mice immunized with SRBC was dose-dependent. The effect potentiating the humoral response occurred for the doses of 0.5-10 mg/kg. The doses of 25 and 50 mg/kg did not affect the immunologic response to SRBC, while the doses of 100 and 250 mg/kg had a suppressive effect. The impact of TPP on the percentage of splenocytes forming E-rosettes was also dose-dependent, but in this case stimulating activity was observed for the doses of 2.5-25 mg/kg.

The effect of Tolpa Peat Preparation on the phagocytic and metabolic activity of neutrophils in normothermic rabbits and with pyrogen-induced fever.

The studies on normothermic rabbits show that intravenous administration of Tolpa Peat Preparation (TPP) at a dose of 5 mg/kg for 3 or 6 consecutive days increases the percentage of phagocytizing cells and the number of bacteria phagocytized by a single neutrophil. The stimulated phagocytic activity of neutrophils coincides with increased nitroblue tetrazolium (NBT) reduction. In contrast, a single administration of TPP to rabbits with fever induced by E.coli lipopolysaccharide (LPS) has a modulating effect on the metabolic activity of neutrophils, depending on TPP dose. TPP administered at a dose of 0.5 mg/kg potentiates the stimulating effect of pyrogen on the percent of NBT-positive neutrophils. A tenfold increase of TPP dose (5 mg/kg) reduces the stimulating effect of LPS and a hundredfold increase (50 mg/kg) leads to total inhibition of LPS-induced changes.

Stimulatory effect of low doses of mechlorethamine on humoral response of ovalbumin-immunized rabbits--comparison with levamisole.

The effect of low doses of mechlorethamine (1-10 micrograms/kg) and levamisole (2.5 mg/kg) on humoral response of rabbits immunized twice with ovalbumin (0.1 mg/kg) was compared. It was shown that mechlorethamine given in a dose of 5 or 10 micrograms/kg potentiates the increase in the level of serum anti-ovalbumin hemagglutinins; this increase is induced both after the first and the second (after 14 days) antigen administration. Levamisole acted similarly but with much lower efficiency.

Responses of neutrophils and lymphocytes in the cold stress: effects of nonsteroid anti-inflammatory drugs.

The cold stress induced in rabbits by lowering their body temperature by 3 degrees C resulted in neutrophilia and a decrease in number of phagocytes and phagocytized bacteria. The stress did not affect the number of lymphocytes and the ability of forming E rosettes by T lymphocytes, but depressed the formation of EAC rosettes by B lymphocytes. This inhibition of neutrophil activity was antagonized completely by acetylsalicylic acid, and substantially by mefenamic acid and indomethacin administered, in doses inhibiting pyrogen-induced fever, either 2.5 h before or 1.5 h after the hypothermia. The drugs did not antagonize the depression of the ability of formation of EAC rosettes.

The dose-dependent influence of mechloretamine on the response to sheep erythrocytes in mice. Comparison of immunostimulating properties of mechloretamine with levamisole.

The effect of the following doses of mechloretamine: 1, 5, 10, 25, 50, 100, 250 and 500 micrograms/kg on the immunological response in mice immunized with sheep red blood cells (SRBC) was investigated. The number of plaque forming cells (PFC) to SRBC, the serum hemagglutinins level and the number of lymphocytes forming E or EAC-rosettes were determined. Depending on mechloretamine dose the following effects on the tested parameters were obtained: (i) only stimulating--1 and 5 micrograms/kg, (ii) stimulating or suppressive according to the test--10-100 micrograms/kg, (iii) only suppressive--250 and 500 micrograms/kg. Mechloretamine (5 micrograms/kg) induced the increase in PFC in comparison with levamisole (2 mg/kg). The difference between the action of mechloretamine and levamisole used in immunostimulating doses on the increased anti-SRBC antibodies or on the E-rosette forming lymphocytes was revealed.

[Immunomodulating effects of low doses of nitrogen mustard derivatives]. / Immunomodulujace dzialanie malych dawek pochodnych iperytu azotowego.

Chlormethine (Nitrogen mustard) in small doses proved to have immunopotentiating and anti-inflammatory activities. The influence of two nitrogen mustard derivatives : chlorambucil (1 or 10 micrograms/kg p.o.) and cyclophosphamide (0.03 or 0.3 mg/kg i.v.) as well as busulphan (0.5 or 5 micrograms/kg p.o.)--the agent of ++alkylating cytostatic group were investigated in rabbits. Whole blood count, the number of T and B lymphocytes, serum IgG level, phagocytic and microbicidal activities of neutrophils and the plasma level of free glucocorticoids were estimated. The drugs were used in the doses 10-100 times lower than cytostatic ones. Moreover, the ability of alkylating drugs to enhance or to suppress the changes evoked by lipopolysaccharide of E. coli in examined parameters was assessed. The results were compared with chlormethine data obtained previously. None of two nitrogen mustard derivatives (chlorambucil or cyclophosphamide) in the doses many times lower than cytostatic ones, exhibited an immunostimulating and adjuvant properties characteristic of chlormethine. Such properties did not demonstrate small doses of busulphan, another compound of alkylating drugs.

Influence of nonsteroid anti-inflammatory drugs on lymphocyte subpopulation and on the primary humoral response in normothermic and feverish rabbits.

Rabbit peripheral blood was tested for the ratio of T and B lymphocytes and for the number of plaque forming cells (PFC) on day 5 and 6 after immunization with sheep erythrocytes. Fever was induced by intravenous injection of lipopolysaccharide (LPS) of E. coli. At higher doses, suppressing the fever, only indomethacin (40 mg/kg per day) inhibited the number of lymphocytes, subpopulation of B cells and their capability for hemolytic antibodies synthesis. This effect was not observed with indomethacin at five fold lower dose. Mefenamic acid (60 mg/kg per day) and acetylsalicylic acid (200-900 mg/kg per day) per se irrespectively of the dose applied, do not affect lymphocyte subpopulations and the primary humoral response. All the three drugs investigated counteracted with the changes in the number of B lymphocytes and PFC induced by LPS.

Pyrogenic fever and blood plasma glucocorticoids after nonsteroid anti-inflammatory drugs.

Rabbits were injected with the lipopolysaccharide from E. coli (LPS) and received orally nonsteroid anti-inflammatory drugs (NSAIDs): acetylsalicylic acid, indomethacin, mefenamic acid, ibuprofen, aminophenazone, metamizole sodium, and phenylbutazone. These NSAIDs exerted antipyretic action without inhibiting the increase in the level of plasma glucocorticoids induced by LPS. This finding indicates the lack of correlation between the pyrogenic action of bacterial pyrogen and pyrogenic increase in the plasma glucocorticoid level. The investigated NSAIDs when given alone to normothermic rabbits differently affected the plasma glucocorticoid level: acetylsalicylic acid, indomethacin and ibuprofen depressed the plasma level of these hormones, mefenamic acid and phenylbutazone elevated it, and aminophenazone and metamizole sodium did not alter it significantly.

Inhibition of postpyrogenic increase of phagocytic and killing activity of neutrophils by nonsteroid antiinflammatory drugs.

Acetylsalicylic acid (300 mg/kg), mefenamic acid (30 mg/kg) or indomethacin (20 mg/kg) given orally in the doses preventing the postpyrogenic fever, inhibited the stimulatory effect of LPS on phagocytic and killing activity of neutrophils. The dose of acetylsalicylic acid that did not eliminate fever in rabbits (100 mg/kg), had no suppressive effect upon fever-stimulated killing activity of neutrophils. The drugs administered twice a day to normothermic animals did not evoke any suppressive changes in the activity of neutrophils.

The influence of copper-dextran complex (C-79), non-steroid anti-inflammatory drugs and bacterial pyrogen on stabilization of rabbit erythrocyte membrane.

We investigated the effect of copper-dextran complex (C-79), acetylsalicylic acid (ASA), mefenamic acid (MEFA) and indomethacin (IND), alone or combined with E. coli lipopolysaccharide (LPS) on osmotic fragility of rabbit erythrocytes. It has been found that LPS in combination with ASA, MEFA, and IND did not change the stabilizing effect of the antipyretics on rabbit erythrocyte membrane. C-79 in doses of 0.4-0.8 mg Cu/kg iv stabilized the erythrocyte membrane for several hours. In lower doses, the compound produced a weak stabilizing effect, and an opposite effect was induced by a dose of 1.6 mg Cu/kg. After administration of C-79 and LPS in combination, the duration of LPS-induced fever was shortened and the erythrocyte stabilization by C-79 was weaker. A combination of ASA with C-79 depressed the body temperature in normothermic animals, while the stabilizing effect of both compounds on the erythrocyte membrane was non-additive.

Chlormethine in small doses as immunostimulator--LPS synergism.

Normothermic rabbits and rabbits with LPS induced fever were treated with chlormethine (Nitrogranulogen, Ntg) in the doses of 1 microgram/kg and 10 micrograms/kg. The blood was collected 4, 24, 48 hrs and 4, 7, 10 days after Ntg injection. Following indices of immunity were studied: T and B cells number, number of IgM producing cells after immunization with SRBC, serum IgG level, killing activity of neutrophils and number of phagocytized bacteria. It was observed that both doses of Ntg injected intravenously to normothermic rabbits, significantly increased the number of T and B lymphocytes and of IgM producing lymphocytes a well as the level of IgG in the serum, number of phagocytized bacteria and killing activity of neutrophils. Ntg in combination with LPS shortened the period of fever, and through the synergistic effect, significantly increased T lymphocytes number in the blood, IgG level in the serum, number of phagocytized bacteria and killing activity of neutrophils.