Restricted diet delays accelerated ageing and genomic stress in DNA-repair-deficient mice

Mice deficient in the DNA excision-repair gene Ercc1 (Ercc1^∆/-) show numerous accelerated ageing features that limit their lifespan to 4-6 months. They also exhibit a 'survival response', which suppresses growth and enhances cellular maintenance. Such a response resembles the anti-ageing response induced by dietary restriction (also known as caloric restriction). Here we report that a dietary restriction of 30% tripled the median and maximal remaining lifespans of these progeroid mice, strongly retarding numerous aspects of accelerated ageing. Mice undergoing dietary restriction retained 50% more neurons and maintained full motor function far beyond the lifespan of mice fed ad libitum. Other DNA-repair-deficient, progeroid Xpg^-/- (also known as Ercc5^-/-) mice, a model of Cockayne syndrome, responded similarly. The dietary restriction response in Ercc1^∆/- mice closely resembled the effects of dietary restriction in wild-type animals. Notably, liver tissue from Ercc1^∆/- mice fed ad libitum showed preferential extinction of the expression of long genes, a phenomenon we also observed in several tissues ageing normally. This is consistent with the accumulation of stochastic, transcription-blocking lesions that affect long genes more than short ones. Dietary restriction largely prevented this declining transcriptional output and reduced the number of γH2AX DNA damage foci, indicating that dietary restriction preserves genome function by alleviating DNA damage. Our findings establish the Ercc1^∆/- mouse as a powerful model organism for health-sustaining interventions, reveal potential for reducing endogenous DNA damage, facilitate a better understanding of the molecular mechanism of dietary restriction and suggest a role for counterintuitive dietary-restriction-like therapy for human progeroid genome instability syndromes and possibly neurodegeneration in general.

Effect of Bovine Granulocyte Colony-Stimulating Factor on the Development of Pneumonia Caused by Mannheimia haemolytica

The role of recruited neutrophils in Mannheimia haemolytica infection is controversial. We hypothesized that the neutrophilia induced by recombinant bovine granulocyte colony-stimulating factor (GCSF) would lead to rapid bacterial clearance and less severe lesions after infection with M. haemolytica. Two experiments (A and B) were conducted in which four calves per experiment were treated daily with 5 μg/kg GCSF and four calves per experiment were treated with saline. All 16 calves were challenged with 5 × 109 colony-forming units (cfu)/ml (experiment A) or 4.5 × 108 cfu/ml (experiment B) of M. haemolytica bacteria, into the right bronchus by bronchoscope-placed catheter. The mean maximal blood neutrophil counts in non-GCSF-treated and GCSF-treated calves before bacterial challenge were 5.6 ± 0.7 × 109/liter and 25.4 ± 2.7 × 109/liter, respectively. Two untreated calves became neutropenic and were euthanatized 2 days after infection because of severe respiratory distress. GCSF-treated calves had a 37% reduction in lung lesions compared with nontreated calves, and this difference was significant ( P = 0.04) when the effect of previous antibody titre to leukotoxin was considered. The effect of GCSF treatment on the severity of clinical signs seemed to be influenced by the antibody titre to M. haemolytica leukotoxin, although this effect could not be conclusively addressed. In conclusion, GCSF induced neutrophilia and partially protected calves against experimental infection with M. haemolytica. These results imply that increased numbers of neutrophils may, under some circumstances, protect against severe pneumonia caused by M. haemolytica.

Amplification of R-spondin1 signaling induces granulosa cell fate defects and cancers in mouse adult ovary

R-spondin1 is a secreted regulator of WNT signaling, involved in both embryonic development and homeostasis of adult organs. It can have a dual role, acting either as a mitogen or as a tumor suppressor. During ovarian development, Rspo1 is a key factor required for sex determination and differentiation of the follicular cell progenitors, but is downregulated after birth. In human, increased RSPO1 expression is associated with ovarian carcinomas, but it is not clear whether it is a cause or a consequence of the tumorigenic process. To address the role of Rspo1 expression in adult ovaries, we generated an Rspo1 gain-of-function mouse model. Females were hypofertile and exhibited various ovarian defects, ranging from cysts to ovarian tumors. Detailed phenotypical characterization showed anomalies in the ovulation process. Although follicles responded to initial follicle-stimulating hormone stimulation and developed normally until the pre-ovulatory stage, they did not progress any further. Although non-ovulated oocytes degenerated, the surrounding follicular cells did not begin atresia. RSPO1-induced expression not only promotes canonical WNT signaling but also alters granulosa cell fate decisions by maintaining epithelial-like traits in these cells. This prevents follicle cells from undergoing apoptosis, leading to the accumulation of granulosa cell tumors that reactivates the epithelial program from their progenitors. Taken together, our data demonstrate that activation of RSPO1 is sufficient in promoting ovarian tumors and thus supports a direct involvement of this gene in the commencement of ovarian cancers.

A20 prevents chronic liver inflammation and cancer by protecting hepatocytes from death

An important regulator of inflammatory signalling is the ubiquitin-editing protein A20 that acts as a break on nuclear factor-κB (NF-κB) activation, but also exerts important cytoprotective functions. A20 knockout mice are cachectic and die prematurely due to excessive multi-organ inflammation. To establish the importance of A20 in liver homeostasis and pathology, we developed a novel mouse line lacking A20 specifically in liver parenchymal cells. These mice spontaneously develop chronic liver inflammation but no fibrosis or hepatocellular carcinomas, illustrating an important role for A20 in normal liver tissue homeostasis. Hepatocyte-specific A20 knockout mice show sustained NF-κB-dependent gene expression in the liver upon tumor necrosis factor (TNF) or lipopolysaccharide injection, as well as hepatocyte apoptosis and lethality upon challenge with sublethal doses of TNF, demonstrating an essential role for A20 in the protection of mice against acute liver failure. Finally, chronic liver inflammation and enhanced hepatocyte apoptosis in hepatocyte-specific A20 knockout mice was associated with increased susceptibility to chemically or high fat-diet-induced hepatocellular carcinoma development. Together, these studies establish A20 as a crucial hepatoprotective factor.

Pathology of the Aging Brain in Domestic and Laboratory Animals, and Animal Models of Human Neurodegenerative Diseases

According to the WHO, the proportion of people over 60 years is increasing and expected to reach 22% of total world’s population in 2050. In parallel, recent animal demographic studies have shown that the life expectancy of pet dogs and cats is increasing. Brain aging is associated not only with molecular and morphological changes but also leads to different degrees of behavioral and cognitive dysfunction. Common age-related brain lesions in humans include brain atrophy, neuronal loss, amyloid plaques, cerebrovascular amyloid angiopathy, vascular mineralization, neurofibrillary tangles, meningeal osseous metaplasia, and accumulation of lipofuscin. In aging humans, the most common neurodegenerative disorder is Alzheimer’s disease (AD), which progressively impairs cognition, behavior, and quality of life. Pathologic changes comparable to the lesions of AD are described in several other animal species, although their clinical significance and effect on cognitive function are poorly documented. This review describes the commonly reported age-associated neurologic lesions in domestic and laboratory animals and the relationship of these lesions to cognitive dysfunction. Also described are the comparative interspecies similarities and differences to AD and other human neurodegenerative diseases including Parkinson’s disease and progressive supranuclear palsy, and the spontaneous and transgenic animal models of these diseases.

Pathology of Mouse Models of Accelerated Aging

Progeroid mouse models display phenotypes in multiple organ systems that suggest premature aging and resemble features of natural aging of both mice and humans. The prospect of a significant increase in the global elderly population within the next decades has led to the emergence of "geroscience," which aims at elucidating the molecular mechanisms involved in aging. Progeroid mouse models are frequently used in geroscience as they provide insight into the molecular mechanisms that are involved in the highly complex process of natural aging. This review provides an overview of the most commonly reported nonneoplastic macroscopic and microscopic pathologic findings in progeroid mouse models (eg, osteoporosis, osteoarthritis, degenerative joint disease, intervertebral disc degeneration, kyphosis, sarcopenia, cutaneous atrophy, wound healing, hair loss, alopecia, lymphoid atrophy, cataract, corneal endothelial dystrophy, retinal degenerative diseases, and vascular remodeling). Furthermore, several shortcomings in pathologic analysis and descriptions of these models are discussed. Progeroid mouse models are valuable models for aging, but thorough knowledge of both the mouse strain background and the progeria-related phenotype is required to guide interpretation and translation of the pathology data.

Equine multinodular pulmonary fibrosis: a newly recognized herpesvirus-associated fibrotic lung disease

Pulmonary fibrosis and interstitial lung disease are poorly understood in horses; the causes of such conditions are rarely identified. Equine herpesvirus 5 (EHV-5) is a gamma-herpesvirus of horses that has not been associated with disease in horses. Pathologic and virologic findings from 24 horses with progressive nodular fibrotic lung disease associated with EHV-5 infection are described and compared with 23 age-matched control animals. Gross lesions consisted of multiple nodules of fibrosis throughout the lungs. Histologically, there was marked interstitial fibrosis, often with preservation of an "alveolar-like" architecture, lined by cuboidal epithelial cells. The airways contained primarily neutrophils and macrophages. Rare macrophages contained large eosinophilic intranuclear viral inclusion bodies; similar inclusion bodies were also found cytologically. The inclusions were identified as herpesviral-like particles by transmission electron microscopy in a single horse. In situ hybridization was used to detect EHV-5 nucleic acids within occasional macrophage nuclei. With polymerase chain reaction (PCR), the herpesviral DNA polymerase gene was detected in 19/24 (79.2%) of affected horses and 2/23 (8.7%) of the control horses. Virus genera-specific PCR was used to detect EHV-5 in all of the affected horses and none of the control horses. EHV-2 was detected in 8/24 (33.3%) of affected horses and 1/9 (11.1%) of the control horses. This disease has not been reported before, and the authors propose that based upon the characteristic gross and histologic findings, the disease be known as equine multinodular pulmonary fibrosis. Further, we propose that this newly described disease develops in association with infection by the equine gamma-herpesvirus, EHV-5.

Avian hepatitis E virus in an outbreak of hepatitis–splenomegaly syndrome and fatty liver haemorrhage syndrome in two flaxseed-fed layer flocks in Ontario

Two commercial layer chicken flocks that were fed a flax-based diet beginning at 28 weeks of age for the production of omega-3 fatty-acid-enriched eggs experienced increased mortality when the birds reached 37 weeks. The average weekly mortality was 0.34% over a 20-week period, with peak mortality of 0.9% for 1 week. Reduced feed consumption, reduced body weight gain and poor peak production were noticed prior to the onset of increased mortality. A total of 245 birds were necropsied and 78% of these had lesions in the liver and spleen, with 44% of those necropsied having changes consistent with hepatitis-splenomegaly syndrome, with lesions ranging from acute periportal lymphoplasmacytic hepatitis to chronic severe cholangiohepatitis with haemorrhage, vasculitis and amyloidosis. A total of 11% of the birds had lesions typical of fatty liver haemorrhagic syndrome, and 22% had lesions found in both hepatitis-splenomegaly syndrome and fatty liver haemorrhagic syndrome. No significant bacteria or viruses were recovered from samples of the liver/bile or spleen but 11 of 21 bile samples contained avian hepatitis E virus RNA detectable with a reverse transcriptase-polymerase chain reaction assay. Comparative sequence analysis found identities of 82 to 92% and 78 to 80% between the helicase and capsid protein genes, respectively, of the virus detected in this outbreak and those of other avian hepatitis E virus isolates, suggesting extensive genetic heterogeneity in avian hepatitis E viruses in Ontario flocks.

Synthesis and antiviral evaluation of n-glycosides derived from 6-amino-3-aryl-2-methyl-4-(3h)-quinazolinones

Reaction of monosaccharides (D-glucose. D-galactose, D-xylose or L-arabinose) with 6-amino-3-aryl-2-methyl-4-(3H) quinazolinones (1a-c) in boiling methanol yielded the corresponding N-glycopyranosides 3a-c, 4a-c, 5a,b and 6a,b. The N-glycopyranosides 3a-c, 4a-c, 5a,b and 6a,b were acetylated with acetic anhydride and pyridine to give the corresponding acetate derivatives 7a-c, 8a-c, 9a,b and 10a,b. The structures of all these glycosides were assessed by elemental analysis, IR, NMR and mass spectra. Some of these products were tested for anti-cancer and anti-AIDS activity.

The antagonistic effect of chlorpromazine on cadmium toxicity

Adult male rats were injected sc with cadmium chloride (CdCl(2)) in a single dose of 7 mg/kg body wt. Twenty-four hours postinjection, exposure to CdCl(2) increased the hemoglobin absorbance of the testes from 0.36 +/- 0.01 to 2.46 +/- 0.02. Pretreatment of rats with chlorpromazine (CPZ) 3 mg/kg ip either for 1 or 2 days before exposure to CdCl(2) significantly (p < 0.05) reduced the testicular damage and the hemoglobin absorbance decreased to 1.03 +/- 0.02 and 0.92 +/- 0.04, respectively. After CdCl(2) injection there was a progressive increase in serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities. CdCl(2) injection induced hemorrhage and a diffuse area of coagulative necrosis in liver. Pretreatment with CPZ partially protected liver from the effect of CdCl(2). Two months postinjection, exposure to CdCl(2) significantly decreased the weights of testes, epididymis, and accessory sex organs. Furthermore, CdCl(2) induced a highly significant (p < 0.01) decrease in sperm cell concentration and the percentage of mobile cells. Moreover CdCl(2) induced degenerative changes in testes, epididymis, and seminal vesicles. Pretreatment with CPZ partially protected these organs from the toxic effects of CdCl(2). It could be concluded that chlorpromazine partially antagonized the toxic effects of cadmium on liver, testes, and other male reproductive organs of rats.

Effect of subclinical lead toxicity on the immune response of chickens to Newcastle disease virus vaccine

The effect of lead acetate (20 and 40 mg kg-1 bodyweight daily) administered via the crop from day old to 56 days of age on the immune response to Newcastle disease virus vaccine (NDVV, La Sota strain) was studied in 354 Lohman chickens. Lead decreased the mitogenic response of peripheral blood lymphocytes (PBL) to phytohaemagglutinin-P (PHA-P) in birds vaccinated with NDVV. It also decreased the weights of the bursa of Fabricius, the thymus glands and the spleen relative to bodyweight. Lead administration decreased the antibody titre to NDVV in the vaccinated groups. The percentage mortality due to a challenge with a virulent velogenic Newcastle disease virus was higher in the lead intoxicated birds.

Influence of Phoxim on testicular and seminal vesicle organs, testosterone and cholinesterase level and its tissue residues in male rats

The effect of Phoxim (Volaton) at two dosage levels (23 and 46 mg/kg b.wt.) on male reproduction tissues and their residues in rats were studied. The tested doses were given orally to male rats for 60 consecutive days. Sex organs weight analysis, semen picture, testosterone and cholinestrase enzyme (ChE) levels, histochemistry, histopathological changes and mating trials were the criteria used to evaluate the reproductive efficiency of the treated rats. There was a dose-related decrease in the weights of testicles and sperm motility associated with an increase in the percentages of dead and morphologically abnormal spermatozoa of treated rats. A decrease in plasma testosterone levels was observed in the treated groups. Histopathological examination revealed that phoxim caused testicular lesions characterized by moderate to severe degenerative changes of spermatogonial cells and by partial arrest of spermatogenesis. Plasma, brain and testicular ChE levels were reduced in treated rats. Phoxim and its oxygen analog concentrations were progressively increased by the time of exposure and represented double fold in liver as compared to that in skeletal muscles and testicles. The histochemical examination of testicles of treated rats showed a marked decreament in the ChE activity in tunica albuginea and sperms. A decrease in this enzyme was also noticed in liver hepatocytes, granular layer of the cerebral cortex and medulla of suprarenal gland.

Interaction between lead toxicity and some sulphonamides in rabbits: effect on certain blood constituents and serum enzymes

Two main equal groups of clinically healthy, non pregnant rabbits were classified into 4 subgroups (5 rabbits each). The 1st and 2nd subgroups were treated with sulphaquinoxaline or sulphadiazine in a single oral dose of 100 mg/kg b. wt., while the 3rd and 4th subgroups received a repeated oral dose of 100 mg/kg b. wt., daily for 5 successive days, respectively. The second main group received lead acetate in a dose of 4.2 mg/kg b. wt. per day for 2 months, then was classified as in case of the 1st main group and administered the respective sulphonamides in their recommended doses. The experimental lead intoxication was found to decrease the free delta-aminolevulinic acid dehydratase (delta-ALA-D) activity in blood of lead intoxicated rabbits after 4 and 8 weeks. Also, the ratio of free and with glutathione reactivated delta-ALA-D was increased 2.9 and 2.2 after 4 and 8 weeks, respectively as compared with before lead administration (1.19), indicating toxicity. The sulphonamide/creatinine ratio was increased after administration of both sulphonamides but higher in lead intoxicated rabbits as compared with healthy ones. The AST/ALT ratio was decreased 4 and 8 weeks after lead exposure. The AST, ALT and AST/ALT ratio, alkaline phosphatase, urea and creatinine were not altered in healthy rabbits. Repeated oral administration of sulphadiazine caused a significant increase in serum AST, ALT, alkaline phosphatase and creatinine level in healthy and lead intoxicated rabbits. On the other hand, AST/ALT ratio in both healthy and lead intoxicated rabbits was found to decrease 1 h after the last dose as compared with before treatment.

Comparative neuromuscular blocking potency of pipecuronium and pancuronium

The effects of pipecuronium bromide (Pi.) and pancuronium bromide (Pa.) on the contractile response of rat-phrenic nerve diaphragm and frog's musculus rectus abdominis preparation were studied. Pi. and Pa. were found to have a dose-dependent reduction in the contractile response of the tested preparation. Trials were made to estimate the potency of Pi. in a comparison with Pa. In this respect Pi. exhibited a more potent effect than Pa. The duration of action is about twice as long as that of Pa. in equieffective doses. Neostigmine rapidly and completely antagonises the neuromuscular blockade caused by Pi. and Pa.

Comparative haemodynamic alterations induced by pipecuronium and pancuronium

Haemodynamic effects of pipecuronium bromide (Pi.) and pancuronium bromide (Pa.) were studied on isolated rabbit's heart, guinea pig's tracheal chain as well as the blood pressure in pentobarbital anaesthetized dogs. Pi. induced negative inotropic and chronotropic effects on the isolated rabbit's heart especially in lower concentrations. However, higher concentrations provoked two opposite effects, negative chronotropic and positive inotropic activity. In addition, Pa. in lower concentrations caused positive inotropic and negative chronotropic activity, while higher concentrations induced negative inotropic and chronotropic activity. Cardioinhibitory actions of both tested drugs are not due to either cholinergic or beta 1-adrenergic blocking effect but it may be due to nicotine-like activity. In anaesthetized dogs, i.v. injections of both tested drugs produced a transient decrease in systolic and diastolic pressure in doses above the therapeutic level. This effect may be referred to the partial ganglion blocking effect of both tested drugs.

Kinetic disposition, systemic bioavailability and tissue distribution of salinomycin in chickens

Salinomycin was administered to chickens orally and intravenously to determine blood concentration, kinetic behaviour, bioavailability and tissue residues. The drug was given by intracrop and intravenous routes in a single dose of 20 mg kg-1 body-weight. The highest serum concentrations of salinomycin were reached half an hour after oral dosage with an absorption half-life (t0.5(ab)) of 3.64 hours and elimination half-life (t0.5(beta)) of 1.96 hours. The systemic bioavailability percentage was 73.02 per cent after intracrop administration, indicating the high extent of salinomycin absorption from this route in chickens. Following intravenous injection the kinetics of salinomycin can be described by a two-compartment open model with a t1/2(alpha) of 0.48 hours, Vd ss (volume of distribution) of 3.28 litre kg-1 and Cl(beta) (total body clearance) of 27.39 ml kg-1 min-1. The serum protein-binding tendency of salinomycin as calculated in vitro was 19.78 per cent. Salinomycin concentrations in the serum and tissues of birds administered salinomycin premix (60 ppm) for two weeks were lower than those after administration of a single intracrop dose of pure salinomycin (20 mg kg-1 bodyweight). The highest concentration of salinomycin residues were present in the liver followed by the kidneys, muscles, fat, heart and skin. No salinomycin residues were detected in tissues after 48 hours except in the liver and these had disappeared completely by 72 hours.

Influence of E. coli infection on the disposition kinetic of nalidixic acid in broiler chickens

The pharmacokinetic data of nalidixic acid were investigated in normal and E. coli infected chickens. The highest serum concentration were reached after 2 hours with t0.5 (ab) of (1.706 +/- 0.1 min in normal and 2.030 +/- 0.11 min in diseased) and (1.72 +/- 0.11 min in normal and 1.416 +/- 0.044 in diseased chickens) following oral and intramuscular administration, respectively. The elimination half-life t0.5 (beta) were (2.514 in normal and 2.35 hr in diseased) and (2.567 hr in normal and 2.672 hr in diseased) respectively. Following intravenous injection the kinetic of nalidixic acid followed two compartments open model with t0.5 of (6.27 and 9.15 hr), Vd (0.45 and 0.79 L/kg), Cltot (8.86 and 13.32 ml/kg/min) in normal and E. coli infected chickens, respectively. Administration of nalidixic acid twice daily for 5 successive days in a dose level of 25 mg/kg b. wt. by oral and intramuscular routes showed a cumulative behaviour.

Disposition of tylosin in goats

The disposition kinetics of tylosin was studied in goats after intravenous or intramuscular injection of 15 mg/kg b. wt. Following i.v. injection, tylosin was rapidly and widely distributed in goats (half life of distribution: 0.2 h and volume of distribution: 1.7 l/kg). It was slowly eliminated with a mean elimination half life of 3.04 h and a total body clearance rate of 6.8 ml/kg/min. Following i.m. injection, tylosin was slowly absorbed (T1/2ab of 1.82 h). Tylosin concentration in serum was greater than 1 microgram/ml after 1 h and persisted up to 12 h post-injection. The peak concentration (Cmax, 2.38 micrograms/ml) was obtained after 4.19 h. The systemic bioavailability of tylosin injected intramuscularly was 72.6% and the serum protein bound fraction was 37.6% of the total drug. Tylosin was excreted in milk and urine at concentrations much higher than that in serum. Low concentrations of tylosin were reported in ruminal juice of goats. In conclusion tylosin should be injected every 15 hours to obtain an appreciable concentration in serum, milk and urine.

Metabolic behaviour and tissue distribution of nalidixic acid in chickens

The metabolic behaviour and tissue distribution of nalidixic acid in normal and E. coli infected chickens were carried out using spectrofluorimetric and microbiological techniques following a single and multiple oral administration of 25 mg/kg b. wt. The obtained results revealed that free nalidixic acid (free NA) is the major fraction of the total drug concentration in serum, liver and kidneys. The free active nalidixic acid was in a higher concentration than hydroxynalidixic acid (free HNA) and both conjugates of NA and HNA following single and multiple oral administration. The obtained results showed that nalidixic acid was highly distributed in all tissues in normal and E. coli infected chickens, with the highest concentrations in kidneys, liver and heart and lowest concentrations in brain, muscles and intestine following oral administration of 25 mg/kg b. wt. twice daily for 5 successive days. Spectrofluorimetic technique was more sensitive for nalidixic acid determination than microbiological method. Nalidixic acid revealed longer withdrawal time in diseased chickens than in normal chickens.

Influence of sodium taurocholate on the potency and duration of action of some neuromuscular blocking agents

The effect of sodium taurocholate (S. T.) on the contractile response of rat-phrenic nerve diaphragm, frog's musculus rectus abdominis and frog's musculus gastrocnemius sciatic nerve preparation was studied. Moreover, interaction of S. T. with neuromuscular blockers are carried out, too. S. T. was found to have a dose-dependent reduction in the contractile response of the tested preparation. On the other hand, the inhibitory effect induced by S. T. did not block or alter the stimulatory effect of either acetylcholine or prostigmine. Trials were made to estimate the potency of S. T. in a comparison with other skeletal muscle relaxant drugs. In this respect S. T. exhibited a more potent effect than gallamine. In contrast, other skeletal muscle relaxants (dtubocurarine, atracurium, pancuronium and succinylcholine) were highly potent. There was also a marked synergistic effect between S. T. and other neuromuscular agents.

Disposition of tylosin in goats

The disposition kinetics of tylosin was studied in goats after intravenous (i.v.) or intramuscular (i.m.) injection of 15 mg/kg body wt. Following i.v. injection, tylosin was rapidly and widely distributed with a distribution half-life of 0.2 h and volume of distribution of 1.7 l/kg. It was slowly eliminated with a mean elimination half-life of 3.04 h and a total body clearance rate of 6.8 ml/kg/min. Following i.m. injection, tylosin was slowly absorbed (tau 1/2 ab of 1.82 h). Tylosin concentration in serum was greater than 1 microgram/ml after 1 h and persisted up to 12 h post-injection. The peak concentration (Cmax 2.38 micrograms/ml) was obtained after 4.19 h. The systemic bioavailability of tylosin injected intramuscularly was 72.6% and the serum protein bound fraction was 37.59% of the total drug. Tylosin was excreted in milk and urine at concentrations much higher than that in serum. Low concentrations of tylosin were reported in ruminal juice of goats. In conclusion tylosin should be injected every 14 h to obtain an appreciable concentration in serum, milk and urine.

Haemodynamic alterations induced by toxic level of sodium taurocholate

Haemodynamic effects of sodium taurocholate (S.T.) were studied on isolated guinea pig's auricles, rabbit's heart, rabbit's aortic strip, guinea pig's tracheal chain as well as the blood pressure and ECG pattern changes in pentobarbital anaesthetized dogs. S.T. induced significant negative inotropic and chronotropic effects on the isolated auricles of guinea pig's especially in higher concentrations. Using isolated rabbit's heart, the negative inotropic and chronotropic effects induced by S.T. were found to be depending on the concentration. Cardio-inhibitory actions of the salt are not due to either cholinergic beta 1-adrenergic blocking effect or nicotine like activity. S.T. in all tested concentrations had no effect on the contractile response of isolated rabbit's aortic strip or guinea pig's tracheal chain and did not prevent the contractile response induced by noradrenaline and histamine. In anaesthetized dogs, i.v. injections of the salt in a dose of 30 mg/kg b. wt. produced a significant decrease in systolic and diastolic pressure, but lower doses induced no significant changes. A dose of 30 mg/kg b. wt. of the salt potentiates the decrease in systolic and diastolic pressure when coadministered with the neuromuscular blocking agent, atracurium besylate. Atropine, propranolol and phentolamine did not alter the hypotensive effect of S.T. (neither cholinergic nor beta 1-adrenergic blocking effect). The electrocardiographic pattern induced by S.T. (20-30 mg/kg b. wt.) in dogs were mainly characterized by decrease in heart rate and prolongation of P-T interval.

Pharmacokinetic profile of cefotaxime in goats

Cefotaxime was once administered in goats via intravenous, intramuscular and subcutaneous routes for determination of blood and urine concentration, kinetic behaviour and bioavailability. Following a single intravenous injection, the blood concentration-time curve indicated two compartments open model, with an elimination half-life value (t1/2 beta) of 22.38 +/- 0.41 minutes. Both intramuscular and subcutaneous routes showed lower values i.e. 38.64 and 69.58 minutes. The lower apparent volume of distribution of cefotaxime in goats than one liter/kg elucidated lower distribution in tissues than in blood. After intramuscular and subcutaneous injections peak plasma cefotaxime concentrations were 77.8 +/- 1.7 and 44.0 +/- 0.8 micrograms/ml at 29.6 and 40.4 minutes, respectively. The average bioavailability of cefotaxime given by intramuscular and subcutaneous injection was 1.08 and 1.25, respectively. The cefotaxime concentration remained in urine 24 hours longer after subcutaneous injection than after intramuscular administration.

Pharmacokinetic profile of cefotaxime in goats

Cefotaxime was administered to goats intravenously, intramuscularly and subcutaneously to determine blood and urine concentration, kinetic behaviour and bioavailability. Following a single intravenous injection, the blood concentration-time curve indicated a two compartment open model, with an elimination half-life value (t1/2 beta) of 22.38 +/- 0.41 minutes. Both intramuscular and subcutaneous routes showed slower values, that is, 38.64 and 69.58 minutes. The apparent volume of distribution of cefotaxime in goats was less than 1 litre kg-1 and suggested a lower distribution in tissues than in blood. After intramuscular and subcutaneous injections peak plasma cefotaxime concentrations were 77.8 +/- 1.7 and 44.0 +/- 0.8 micrograms ml-1 at 29.6 and 40.4 minutes, respectively. The average bioavailability of cefotaxime given by intramuscular and subcutaneous injection was 1.08 and 1.25 times the intravenous availability, respectively. The cefotaxime concentration remained in urine 24 hours longer after subcutaneous injection than after intramuscular administration.

Ruminal excretion of sulfadimethoxine and sulfadimethyloxazole in goats and their influence on some enzyme activities and renal clearances

Five clinically health goats were injected with sulfadimethoxine and sulfadimethyloxazole in a single dose of 100 mg/kg b. wt. by intravenous route. Highest concentration levels of sulfadimethoxine and sulfadimethyloxazole in rumen were detected 1 hour following intravenous injection, then the concentration for both compounds declined at 12 and 8 hours post administration, respectively. In addition, both types of sulfonamide completely disappeared in ruminal fluid samples taken after 24 and 12 hours, respectively. The rate of acetylation for sulfadimethoxine and sulfadimethyloxazole were nearly similar and occurred to a high extent in ruminal fluid (22.95 and 23.72%, respectively). On the other hand, both tested drugs increased significantly the ruminal gas production from the first to eight hours after i.v. injection in goats. Changes in the serum enzyme activities (SGOT, SGPT and alkaline phosphatase) observed with sulfadimethoxine and sulfadimethyloxazole, and represented by a significant decrease in the activity of SGOT and SGPT level, alkaline phosphatase 4 hours sulfadimethoxine and in GOT/GPT ratio 24 and 48 hours after i.v. injection, respectively. The creatinine clearance was significantly decreased after 4 hours following the i.v. administration of sulfadimethoxine and sulfadimethyloxazole in goats.

Kinetic disposition, systemic bioavailability, tissue levels and acetylation of some sulphonamides in goats

Sulphamethoxazole, sulphadimethyloxazole and sulphadimethoxine were once administered in goats via oral and i.v. route (100 mg/kg b.wt.) for determination of plasma and urine concentrations of the unchanged sulphonamides and their acetylated derivatives, kinetic behavior, systemic bioavailability, tissue levels and acetylation. The highest plasma concentrations of sulphamethoxazole, sulphadimethyloxazole and sulphadimethoxine were reached after 0.64, 1.31 and 0.46 hr following oral administration, with an absorption half-life of 0.84, 1.31 and 0.38 hr and an elimination half-life of 3.51, 5.01 and 5.55 hr, respectively. Following a single i.v. injection, the kinetic disposition of sulphamethoxazole and sulphadimethoxine followed a one-compartmental model with an elimination half-life of 1.48 and 1.76 hr and a total body clearance-time curve of sulphadimethyloxazole, after a single i.v. injection, could be described by a two-compartmental open model with an elimination half-life of 3.27 hr, a volume of distribution of 248.07 ml/kg and a total body clearance of 0.82 ml/kg/min. The systemic bioavailability was 19.95, 11.37 and 23.27% after oral administration of sulphamethoxazole, sulphadimethyloxazole and sulphadimethoxine, respectively. The percentages of serum protein binding of sulphamethoxazole, sulphadimethyloxazole and sulphadimethoxine were determined in most of the body tissues, collected 4 hr after i.v. injection. The highest concentration was found in kidney and liver. On the other hand, sulphamethoxazole, sulphadimethyloxazole and sulphadimethoxine were N4-acetylated in the body tissues to a higher extent than that in plasma. Acetylation was highest in rumen and skeletal muscle.

Sulphonamides in buffaloes: effect on certain blood constituents and serum enzymes

1. Three groups of four clinically healthy buffaloes were injected with sulphadiazine, or sulphadimidine, or sulphathiazole in a single dose of 100 mg/kg body weight. 2. Changes in the serum enzyme activities (SGOT, SGPT and alkaline phosphatase) observed with the tested sulphonamides were insignificant, except for increases in SGOT level 6 h after sulphathiazole injection, and in GOT/GPT ratio 30 min and 24 h after sulphadimidine injection. 3. The creatinine level was not affected in sulphonamide-injected animals. All blood samples collected 15 min to 24 h after sulphathiazole injection showed marked increase in glucose and urea levels. Concerning the other two sulphonamides, no significant change was observed in these parameters except for an increased glucose level 24 h after sulphadiazine injection.

Some pharmacokinetic and biochemical aspects of sulphadiazine and sulphadimidine in ewes

Eight experiments were carried out on eight clinically healthy non-pregnant ewes. Each animal was injected intravenously with either sulphadiazine or sulphadimidine at a dose rate of 100 mg/kg body weight. A two-compartment pharmacokinetic model was developed to describe the disposition of these drugs. The elimination half-lives were 7.15 +/- 0.58 h and 9.51 +/- 0.59 h and the distribution half-lives were 0.56 +/- 0.07 h and 0.42 +/- 0.05 h for sulphadiazine and sulphadimidine, respectively. The apparent specific volumes of distribution were less than 1 litre/kg (0.410 and 0.501 litres/kg for sulphadiazine and sulphadimidine, respectively) which indicates a relatively lower distribution of these drugs to tissues than in plasma in sheep. The degree of plasma protein binding was similar for both drugs (19.15 +/- 0.55% and 23.12 +/- 0.32%) for sulphadiazine and sulphadimidine, respectively). Serum concentrations of ketone bodies, total lipids and calcium were significantly reduced, and blood glucose concentration significantly increased following administration of both of these sulphonamides, whilst serum total protein concentration was unaltered. The serum cholesterol concentration was significantly reduced following sulphadiazine administration, but not after sulphadimidine.

Disposition kinetics of furosemide in dogs

In 12 experiments on 6 mongrel dogs, furosemide was given both orally and i.v. in a dose of 20mg/kg. Following i.v. injection, the blood concentration curve followed an open one-compartment model. The elimination half-lives after both oral and i.v. routes were nearly similar, i.e. 1.42 +10.13 and 1.13 +0.06 hours respectively. The apparent volume of distribution corresponded well to the total body water (about 60%), i.e. 69.64 +5.61 and 52.06+4.82% b.wt. after oral and i.v. routes respectively. The body clearance of this drug after i.v. and oral administration showed close values, i.e. 5.27 +0.19 and 5.96 +0.14 mg/kg(-1) min(-1) respectively. The systemic bioavailablity of furosemide after oral administration amounted to 77.13 +5.24% with a maximum blood conc. (Cmax.) of 22.73 +2.03 microgram/ml, 30 min after administration.

Fortification of some Egyptian foods with soybean

Flours from full fat and defatted soybeans were made in the laboratory and used as supplements to Egyptian bread and two popular legume foods (lentil soup and falafil). The effect of fortification level on water absorption, dough rheology, loaf quality, and major chemical constituents of fino (pulp) and Arabic (flat) breads were investigated. Water absorption was slightly affected, dough mixing time, stability, and valorimetric values increased, but the mixing tolerance index decreased by adding defatted soy flour to wheat flour. Loaves were slightly smaller in volume than the control at high levels of defatted soy flour. Morover, bread score and panel evaluation showed deterioration of fino bread characteristics above 6% and Arabic bread above 8% defatted soy flour, but above 3% full fat soy. Organoleptic properties of the enriched lentil soup and falafil were similar to those of control at a level of 25% and 50% full fat soy and of 40% and 60% defatted soy flour, respectively. The most favorable change of the chemical composition of lentil soup and falafil is the increased protein content. Also, increasing the level of defatted soy flour increased ash content and decreased the level of fat absorption by fried falafil. On the other hand, increasing the level of full fat soy may replace the addition of shortening to lentil soup to make it more palatable.