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PubMed2003

The disposition of diclofenac in camels after intravenous administration.

The pharmacokinetics of diclofenac was studied in camels (Camelus dromedarus) (n=6) following intravenous (i.v.) administration of a dose of 2.5 mg kg(-1) body weight. The metabolism and urinary detection time were also studied. The results obtained (median and range) were as follows: the terminal elimination half-life (t(1/2beta)) was 2.35 (1.90-2.73)h, total body clearance (Cl(T)) was 0.17 (0.16-0.21)lh kg(-1). The volume of distribution at steady state (V(SS)) was 0.31 (0.21-0.39)l(-1)kg(-1), the volume of the central compartment of the two compartment pharmacokinetic model (V(C)) was 0.15 (0.11-0.17)l kg(-1). Five metabolites of diclofenac were tentatively identified in urine and were excreted mainly in conjugate form. The main metabolite was identified as hydroxy diclofenac. Both diclofenac and hydroxy diclofenac, appear to be the main elimination route for diclofenac when administered i.v. in camels. Diclofenac could be identified up to 4 days following i.v. administration in camels using a sensitive gas chromatography/mass spectrometry (GC/MS) method.

Animals↗
PubMed1999

Purification and some properties of camel carboxypeptidase B.

A carboxypeptidase B-like enzyme was purified 116-fold with a recovery of activity of 29% from a crude extract of camel pancreas by a four-step procedure consisting of two anion exchange chromatographies in succession, gel filtration and hydrophobic interaction chromatography. The enzyme was homogeneous on SDS and non-denaturing gel electrophoresis and on gel isoelectric focusing. Its molecular mass was found to be 31.5 kDa and its isoelectric point was estimated as 6.1. It was active towards a number of substrates that are cleaved by carboxypeptidases B from other species and was also susceptible to inhibition by inhibitors of such enzymes. The camel enzyme showed a pH optimum of 8.0 and it was seen to be a relatively potent kininase in vitro. The enzyme purified in this study was very similar to carboxypeptidases B isolated from other species in size, charge, substrate specificity and susceptibility to inhibition and thus it can be identified as camel carboxypeptidase B.

Animals↗
PubMed2000

Purification and characterization of cationic chymotrypsin from the pancreas of the Arabian camel (Camelus dromedarius).

This study reports on the purification and characterization of a cationic enzyme with chymotryptic activity from camel pancreas. The enzyme was purified 52-fold in a 48% yield by a three-step chromatographic procedure consisting of anion-exchange, cation-exchange and affinity chromatographies. The purified enzyme was homogeneous on gel isoelectric focusing and on SDS gel electrophoresis. Its isoelectric point was estimated to be 7.3 and its molecular mass was found to be 23,600 Da. The enzyme was identified as a cationic chymotrypsin according to its physiochemical properties, substrate specificity and susceptibility to inhibition. It was active towards esters of aromatic amino acids but much less active towards a leucine ester. In all cases, the k(cat) values of the camel enzyme were less than the corresponding values of bovine chymotrypsin A. It also showed a lower level of kininase activity. Camel chymotrypsin was more susceptible than its bovine equivalent to inhibition by soybean trypsin inhibitor and aprotinin. It showed the same pH optimum as bovine chymotrypsin A for its esterolytic activity, but was more dependent on CaCl2 for long-term stability.

Animals↗
PubMed2004

Salmonella prevalence and distribution of serotypes in apparently healthy slaughtered camels (Camelus dromedarius) in Eastern Ethiopia.

The present study was undertaken to determine the prevalence and distribution of Salmonella from apparently healthy slaughtered camels in Eastern Ethiopia. A total of 714 samples (faeces, mesenteric, lymph nodes, spleen, liver, abdominal and diaphragmatic muscles) from 119 slaughtered camels were analysed. Salmonellae were detected from 116 (16.2%) of the 714 samples examined. Eighteen (15.1%) faeces, 19 (15.9%) mesenteric lymph nodes, 14 (11.8%) livers and 17 (14.3%) spleen samples (n = 119 for each) were positive for Salmonella. Salmonellae were found in 20.1% of the abdominal and diaphragmatic muscles. A total of sixteen different serotypes were identified of which Salmonella saintpaul (38.8%) and S. braenderup (22.4%) were the most prevalent followed by S. muenchen (8.6%), S. kottbus (6.0%) and S. havana (5.2%). Other serotypes, including S. typhimurium, S. heidelberg and S. enteritidis were also detected from Ethiopian camels.

Animals↗
PubMed2004

The zinc and copper content of the plasma of Sudanese camels (Camelus dromedarius).

A study was undertaken to investigate the variations in the content of zinc and copper in the plasma of Sudanese camels (Camelus dromedarius). A total of 993 Arabi camels, aged 0.5-8 years, were used to assess the effect of season, age, sex and physiological status on the plasma concentrations of copper and zinc. There was an increase in the concentration of Cu and a decrease in the concentration of Zn in the plasma with age. The concentrations of both Cu and Zn in the plasma were higher in the rainy season than in the dry season. The plasma copper concentrations in pregnant, low-lactating and high-lactating camels were 81.3 +/- 4.7, 59.7 +/- 6.1 and 61.3 +/- 5.5 microg/100 ml, respectively. The corresponding values for zinc were 51.0 +/- 8.9, 53.4 +/- 6.4 and 67.1 +/- 5.5 microg/100 ml, respectively. However, there was no effect of sex on the content of these minerals in the plasma.

Animals↗
PubMed2007

Studies of thermostability in Camelus bactrianus (Bactrian camel) single-domain antibody specific for the mutant epidermal-growth-factor receptor expressed by Pichia.

Camelids have a unique immune system capable of producing heavy-chain antibodies lacking the light chains and CH1 (constant heavy-chain domain 1). It has been shown that, in contrast with conventional antibody fragments, the variable domains of these heavy-chain antibodies are functional at or after exposure to high temperatures. In the present study, the VHH (variable domain of heavy-chain antibody) camel antibody was subcloned into vector Ppiczc and expressed in Pichia pastoris. ORB1-83 VHH antibody recognizes the external domain of the mutant EGFR [EGF (epidermal growth factor) receptor], EGFR VIII. This tumour-specific antigen is ligand-independent, contains a constitutively active tyrosine kinase domain and has been shown to be present in a number of human malignancies. We report here that, although expression from P. pastoris resulted in a significantly increased level of expression of the anti-EGFR VIII VHH antibodies compared with Escherichia coli [Omidfar, Rasaee, Modjtahedi, Forouzandeh, Taghikhani, Bakhtiari, Paknejad and Kashanian (2004) Tumor Biol. 25, 179-187; Omidfar, Rasaee, Modjtahedi, Forouzandeh, Taghikhani and Golmakany (2004) Tumor Biol. 25, 296-305], this antibody selectively bound to the EGFR VIII peptide and reacted specifically with the immunoaffinity-purified antigen from non-small-cell lung cancer. Furthermore, thermal denaturation stability and CD spectra analysis of the Camelus bactrianus (Bactrian camel) VHH and heavy-chain antibodies at different temperature proved reversibility and binding activity after heat denaturation. Our results indicate that the P. pastoris expression system may be useful for the expression of camel single domain antibody and the ability of the expressed protein to reversibly melt without aggregation, allowing it to regain binding activity after heat denaturation.

Animals↗
PubMed1966

Camel myoglobin.

1. Crystalline myoglobin was prepared from camel heart muscle. 2. A method was developed for the isolation of myoglobin that employs molecular-sieve chromatography. 3. Analytical chromatography of the camel myoglobin on a molecular-sieve column and on two types of ion-exchange columns gave in each case a single elution band, which accounted for better than 98% recovery and showed that the product was free from haemoglobin. 4. The iron content on a dry weight basis was 0.308%. This value corresponds to a molecular weight of 18100. 5. The spectra of acidic ferrimyoglobin, basic ferrimyoglobin and ferrimyoglobin cyanide were measured. 6. The pK(a) of the dissociation of the haem-bound water molecule in acidic ferrimyoglobin was 8.53 at 25 degrees . 7. Conclusions are drawn about the charge on the surface of the camel ferrimyoglobin molecule as compared with horse and sperm-whale ferrimyoglobins.

Animals↗
PubMed2002

The pharmacokinetics, metabolism and urinary detection time of etamiphylline in camels after intramuscular administration.

The pharmacokinetics of etamiphylline were determined after an intramuscular (i.m.) dose of 3.5 mg/kg body weight in six healthy camels. Furthermore, the metabolites and drug detection time were evaluated. The data obtained median and (range) were as follows: the terminal elimination half-life (t(1/2 beta), h) was 3.04 (2.03-3.62); apparent total body clearance (Cl/F, L/h/kg) was 1.27 (0.74-2.99); the apparent volume of distribution at steady state (V(ss)/F, L/kg) was 4.94 (3.57-12.54); and renal clearance (Cl(r), L/h/kg) determined in two camels was 0.005 and 0.004, respectively. The detection time of etamiphylline in urine after an i.m. dose of 3.5 mg/kg body weight ranged between 12 and 13 days. Three etamiphylline metabolites were tentatively identified in camels urine: The first one desethyletamiphylline was the main metabolite and resulted from N-deethylation of etamiphylline had a molecular weight of 251, and was detected in urine for about 13-14 days. Theophylline (molecular weight 180) was the second metabolite and resulted from ring N-dealkylation of etamiphylline. It was present in small amounts and was detected for about 5 h after drug administration in urine. The third metabolite, possibly resulted from demethylation of etamiphylline, had a molecular weight of m/z 265, and was present in small amounts and was detected in urine for about 5 h after drug administration.

Animals↗
PubMed1999

Ultrastructure of the thyroid gland of the one-humped camel (Camelus dromedarius).

Follicular epithelium of the thyroid gland of the one-humped camel was examined by light and electron microscopy. It consisted of a single type of epithelial cell which varied from flattened to columnar in shape. Follicular epithelial cells were characterized by the presence of markedly dilated cisternae of rough-surfaced endoplasmic reticulum, well developed Golgi apparatus, abundant small vesicles (150 nm to 200 nm in diameter) in the apical cytoplasm, and electron-dense colloid droplets measuring from 250 nm to 1600 nm. Follicular epithelial cells frequently showed apocrine secretion into colloidal lumens. Apocrine protrusions with smooth surface were dome-like or balloon-like structures and contained a fine granular matrix. These findings indicate that the morphological features of the follicular epithelial cells of the thyroid gland of the camel are essentially similar to those of mammals except for the presence of apocrine secretion, which is unique to the camel.

Animals↗
PubMed1999

Ultrasonographic determination of the dimensions of ocular components in enucleated eyes of the one-humped camel (Camelus dromedarius).

The refractive status and visual capabilities of the one-humped camel are not currently known. Schematic eyes are important tools in studying the optical characteristics and refractive status of an eye. The variables required in developing a schematic eye for a particular animal species include the dimensions of the optical components. We have employed A-scan ultrasonography to measure the dimensions of optical components in freshly enucleated eyes of the one-humped camel. Measurements were made in eyes immersed in distilled water kept at 20 degrees C. The average values of the optical components were as follows: anterior chamber depth = 5.27 mm, lens thickness = 10.93 mm, vitreous chamber depth = 14.85 mm and axial length = 31.05 mm. The uncorrected average corneal thickness was 0.76 mm. These values would have to be confirmed in live animal subjects before they can be used to design a schematic eye for the one-humped camel.

Animals↗
PubMed2000

The pharmacokinetics, metabolism and urinary detection time of caffeine in camels.

The pharmacokinetics of caffeine were determined in 10 camels after an intravenous dose of 2.35 mg kg(-1). The data obtained (median and range) were as follows. The elimination half-life (t(1/2)) was 31.4 (21.2 to 58.9) hours, the steady state volume of distribution (V(SS)) was 0.62 (0.51 to 0.74) litre kg(-1)and the total body clearance (Cl(T)) was 14.7 (8.70 to 19.7) ml kg(-1)per hour. Renal clearance estimated in two camels was 0.62 and 0.34 ml kg(-1)per hour. In vitro plasma protein binding (mean +/-SEM, n = 10) to a concentration of 2 and 8 microg ml(-1)was 36.0 +/- 0.24 and 39.2 +/- 0.36 per cent respectively. Theophylline and theobromine were identified as caffeine metabolites in serum and urine. The terminal elimination half-life of the former, estimated in two camels, was 70. 4 and 124.4 hours. Caffeine could be detected in the urine for 14 days.

Animals↗
PubMed2000

Camel single-domain antibodies as modular building units in bispecific and bivalent antibody constructs.

Single-domain antibodies against various antigens are isolated from the unique heavy-chain antibodies of immunized camels and llamas. These minimal sized binders are very robust and bind the antigen with high affinity in a monomeric state. We evaluated the feasibility to produce soluble, functional bispecific and bivalent antibodies in Escherichia coli with camel single-domain antibody fragments as building blocks. Two single-domain antibody fragments were tethered by the structural upper hinge of a natural antibody to generate bispecific molecules. This linker was chosen for its protease resistance in serum and its natural flexibility to reorient the upstream and downstream located domains. The expression levels, ease of purification, and the solubility of the recombinant proteins were comparable with those of the constituent monomers. The individual moieties fully retain the binding capacity and the binding characteristics within the recombinant bispecific constructs. The easy generation steps and the biophysical properties of these bispecific and bivalent constructs based on camel single-domain antibody fragments makes them particularly attractive for use in therapeutic or diagnostic programs.

Amino Acid Sequence↗
PubMed2001

Antigen specificity and high affinity binding provided by one single loop of a camel single-domain antibody.

Detailed knowledge on antibody-antigen recognition is scarce given the unlimited antibody specificities of which only few have been investigated at an atomic level. We report the crystal structures of an antibody fragment derived from a camel heavy chain antibody against carbonic anhydrase, free and in complex with antigen. Surprisingly, this single-domain antibody interacts with nanomolar affinity with the antigen through its third hypervariable loop (19 amino acids long), providing a flat interacting surface of 620 A(2). For the first time, a single-domain antibody is observed with its first hypervariable loop adopting a type-1 canonical structure. The second hypervariable loop, of unique size due to a somatic mutation, reveals a regular beta-turn. The third hypervariable loop covers the remaining hypervariable loops and the side of the domain that normally interacts with the variable domain of the light chain. Specific amino acid substitutions and reoriented side chains reshape this side of the domain and increase its hydrophilicity. Of interest is the substitution of the conserved Trp-103 by Arg because it opens new perspectives to 'humanize' a camel variable domain of heavy chain of heavy chain antibody (VHH) or to 'camelize' a human or a mouse variable domain of heavy chain of conventional antibody (VH).

Amino Acid Sequence↗
PubMed1986

Dermatophytosis of camels.

A survey of ringworm in camels showed over 25% of young animals suffered from T. verrucosum infection, and fewer than 0.5% of the camels had T. mentagrophytes. Amino acid analyses of hair samples taken from human, camel and cow showed the compositions were similar to within 11%.

Amino Acids↗
PubMed2001

Fatty acids and lipids of camel milk and colostrum.

Total fat content was 32.8 +/- 14 g/L in camel milk (10-240 days post partum) or 30.1 +/- 19.5 g/L in colostrum (1-7 days post partum). Triacylglycerols accounted for 96% of the total lipids in milk. Triacyglycerols of camel milk contained saturated fatty acids (66.1%) and unsaturated fatty acids (30.5%). The predominant saturated fatty acids were 16:0 (34.9%) 14:0 (14.5%) and 18:0 (9.7%). The content of these fatty in acids in colostrum was lower (52.4%) than that of mature milk. The colsotrum contained a relatively high amount of 18:1 (25.4%), and 16:1 (13.9%), with the remainder being a mixture of dienoic and trienoic long-chain fatty acids. Triacylglycerols contained low amount of short-chain fatty acids (C4-C8). There is a high content of polyunsaturated fatty acids in camel colostrum and milk.

Animals↗
PubMed1996

The nature of the inhibition of camel retina acetylcholinesterase (EC 3.1.1.7) activity by tetrahydroaminoacridine.

The nature of the inhibition of camel retina acetylcholinesterase (AChE) activity by tetrahydro-aminoacridine (THA, tacrine) has been investigated in the present study. The non-significant change of the percent inhibition of AChE by THA with respect to various lengths of the preincubation period showed the type of the reversible inhibition. THA reversibly inhibited AChE activity in a concentration dependent manner; IC50 was 0.23 microM while the IC100 was 14.22 microM. The K(m) for the hydrolysis of acetylthiocholine iodide was found to be 62.6 microM in the control system; a value increased in the THA treated systems. The Vmax was 0.472 mumole/min/mg protein for the control system, while it decreased in the THA treated systems. Dixon, as well as Lineweaver-Burk, plots and their secondary replots indicated that the nature of the inhibition is of the linear mixed type, which is considered to be a partial competitive and pure non-competitive mixture. The values of Ki(slope) and K'i(intercept) were estimated as 0.068 microM and 0.181 microM, respectively. The K'i was greater than Ki indicating that THA has a greater affinity of binding for the peripheral site than the active site of the camel retina AChE. The use of camel retina as a good experimental animal model may open new avenues for studying acetylcholine and AChE metabolism.

Acetylcholine↗
PubMed1986

Mating-induced luteinizing hormone surge and ovulation in the female camel (Camelus dromedarius).

Blood samples were collected after mating from four female one-humped camels every 10 min for 9-12 h. Luteinizing hormone (LH) was quantified in plasma by radioimmunoassay using antibovine LH. Of the seven observed matings, five were followed by a release of LH, and three by an ovulation (indicated by a subsequent secretion of progesterone). LH levels at the time of mating ranged from 0.7 to 3 ng/ml. When an LH response occurred, the levels increased 1 h after mating and reached a maximum in 2-3 h (ranging from 2.9 to 19.1 ng/ml). A decrease in LH was observed starting 6 h after mating and lasting for 6 h. These results are in agreement with a coitus-induced mechanism of ovulation in the one-humped camel (Camelus dromedarius). They confirm and extend the observations reported in the bactrian camel (Camelus bactrianus).

Animals↗