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PubMed1998

Multiplicity and tissue specific expression of camel cytochrome P450(s).

The presence of multiple forms of the cytochrome P450 was demonstrated enzymatically in camel tissues using a variety of isoenzyme specific substrates and immunochemically using isoenzyme specific antibodies. The maximum catalytic activity using xenobiotics as substrate was observed in the liver followed by the kidney. However, lauric acid hydroxylation was found to be higher in the kidney than in any other tissues. Camel liver microsomal monooxygenase activity using aniline, aminopyrene, ethoxycoumarin, ethoxyresorufin and benzo(a)pyrene as substrates was comparable with those of rat and human livers. The activity of the enzymes in extrahepatic tissues of the camel was comparable with those of the rat extrahepatic tissues. The maximum expression of P450 protein was seen in the camel liver and kidney while the brain and intestine exhibited relatively low levels of expression. P450 expression in camel tissues appeared to be higher than in rat tissues. Immunohistochemical staining of P450 in the camel liver, kidney and brain confirmed the higher expression of P450 enzyme proteins in the liver and kidney as compared to other extrahepatic tissues. The maximum expression of P450 in the liver was observed in hepatocytes around the central vein and in the kidney it was observed in the proximal tubules. These results demonstrate that the multiple forms of P450s are differentially expressed in camel tissues and that the relative levels of expression are comparable with those of rat and human tissues. These observations may be important in understanding the differential susceptibility of camel tissues to the toxic/therapeutic effects of xenobiotics/drugs and environmental pollution.

Animals↗

PubMed2002

Immunohistochemical investigations of the autonomous nerve distribution in the testis of the camel (Camelus dromedarius).

The distribution of autonomous nerves in the testis of the camel was studied by immunohistochemical methods. A total of 26 testes was collected during the different seasons of the year. As pan-neuronal markers, antibodies to protein gene product 9.5 and to neurofilaments are superior to antibodies against neuron-specific enolase and acetylcholinesterase histochemistry for the description of the nerves in the camel testis. Testicular nerves reach the camel testis by three access-routes as (1) funicular contribution, (2) mesorchial contribution and (3) as caudal contribution. The main target for testicular nerves is the arterial vascular tree of the organ, whereas all veins of testis and pampiniform plexus are devoid of any innervation in the camel. In the wall of the arteries, the nerves form a plexus at the media-adventitia border. The density of the arterial plexuses increases along the vascular tree: smaller septal and mediastinal arteries are better innervated than albugineal arteries and the latter better than the A. testicularis. The nerves in the septula testis, in the mediastinum and between the Leydig cells show clear seasonal changes, being particularly abundant in autumn and particularly scarce in spring. The nerves that reach the camel testis are unmyelinated and represent in the vast majority postjunctional sympathetic neurons. Cholinergic fibers are absent in the camel testis. Neuropeptide Y is the dominating peptidergic transmitter in the testicular nerves and colocalized with noradrenaline in the same axons. Vasoactive intestinal polypeptide-containing fibers reach the camel testis exclusively as parts of the caudal nervous contribution via the ligamentous bridge between testis and epididymal tail and are restricted to the caudal pole of the testis. Calcitonin gene-related peptide-positive axons are not frequent in the camel testis; nevertheless, they seem to be the most important sensory pathway of this organ.

3-Hydroxysteroid Dehydrogenases↗

PubMed2002

Vitamin C concentrations in blood plasma, tissues and urine of camels (Camelus dromedarius) in Sudanese herds.

There is suggestive evidence that a low status of ascorbic acid in ruminants is related with decreased disease resistance. In a first attempt to identify conditions in camels that could affect their health, an inventory was made of ascorbic acid (vitamin C) concentrations in plasma and tissues as related to breed, gender, sexual activity and season. A total of 3429 camels were studied and sub-samples were used for selected comparisons. The highest concentrations of ascorbic acid were found in adrenals (152 mg/100 g wet tissue) and the lowest in heart (8 mg/100 g), the levels being unrelated with season. Arabi camels had higher plasma concentrations of ascorbic acid (6.42 microg/ml) than did Anafi and Bishari camels, the latter breed showing the lowest concentrations (3.24 microg/ml). Female camels of the Anafi breed had higher concentrations urinary ascorbic acid than did their male counterparts. It is suggested that in camels the main elimination route of vitamin C is with urine. Female and male Arabi camels that were sexually active had 52 and 23% lower plasma ascorbic acid concentrations than did their sexually inactive counterparts. It is suggested that especially Bishari camels during the breeding season might be sensitive to disease.

Adrenal Glands↗

PubMed2005

Embryo transfer in the dromedary camel (Camelus dromedarius) using asynchronous, meclofenamic acid-treated recipients.

A total of 40 (Day 7) embryos were recovered from the uteri of 10 superovulated camels. Recipient camels (n = 30) were prepared by injection with 20 (1/4)g of the gonadotrophin-releasing hormone analogue buserelin (i.v.) to induce ovulation and then treatment with 1 g meclofenamic acid (a prostaglandin synthetase inhibitor), orally, once on Day 7 and twice daily on Days 8 and 9 after ovulation and thereafter at a dose of 1 g day(-1) until 8 days after embryo transfer. Embryos were transferred into recipients on Day 8 (n = 10), Day 10 (n = 10) or Day 12 (n = 10) after ovulation and another 10 embryos were transferred into untreated recipients on Day 8 after ovulation as controls. In addition, serum samples from all recipient camels were recovered daily throughout the period of meclofenamic acid administration and for a further 7 days after treatment had ceased and were assayed for progesterone concentrations. Results showed that whereas only one of 10 of the control group of recipients (10%) was diagnosed pregnant, a total of eight of 10 Day 8 (80%), six of 10 Day 10 (60%) and seven of 10 Day 12 (70%) recipients were diagnosed pregnant by ultrasonography 12 days after the embryo had been transferred. Subsequently, however, four pregnancies were lost when the conceptus was aged between 22 and 60 days, but this is not considered above the early fetal mortality rate expected in camels after natural mating or after transferring camel embryos to untreated recipients. Serum progesterone concentrations remained elevated, above 2 ng mL(-1), throughout the period of meclofenamic acid administration in all recipient camels; thereafter, concentrations remained above 2 ng mL(-1) in pregnant animals, whereas in non-pregnant camels concentrations had declined to baseline values (<1 ng mL(-1)) within 3 days of the end of the treatment period. In conclusion, treatment of recipient camels with meclofenamic acid reduced the need for tightly timed synchrony between donor and recipient because pregnancies were established in recipients that had ovulated as much as 5 days ahead of the donor.

Animals↗

PubMed2003

CD4+ Th2 cell recognition of HLA-DR-restricted epitopes derived from CAMEL: a tumor antigen translated in an alternative open reading frame.

Tumor Ag NY-ESO-1 is an attractive target for immunotherapy of cancer, since both CD8(+) CTL and CD4(+) Th cells against NY-ESO-1 have been described. Moreover, NY-ESO-1 as well as the highly homologous tumor Ag LAGE-1 are broadly expressed in various tumor types. Interestingly, the NY-ESO-1 and LAGE-1 genes also encode for proteins translated in an alternative open reading frame. These alternatively translated NY-ESO-ORF2 and CAMEL proteins, derived from the NY-ESO-1 and LAGE-1 genes, respectively, have been demonstrated to be immunogenic, since CTL specific for these proteins have been isolated from melanoma patients. In this study a panel of advanced melanoma patients was screened for the presence of Th cells specific for the alternatively translated tumor Ags NY-ESO-ORF2 and CAMEL. PBMC of melanoma patients were stimulated for 4 days with mixes of overlapping peptides covering the entire NY-ESO-ORF2 and CAMEL protein sequences and were tested for the release of type 1 (IFN-gamma) and type 2 (IL-13) cytokines in ELISPOT assays. In three of 15 patients, T cells specific for two CAMEL peptides (CAMEL(71-92) and CAMEL(81-102)) could be detected. From one of these patients, CD4(+) T cell clones specific for CAMEL(81-102) could be generated. These clones recognized a naturally processed epitope presented in both HLA-DR11 and HLA-DR12 and produced high levels of IL-4, IL-5, and IL-13. In conclusion, this study shows the presence of Th cells specific for the alternatively translated tumor Ag CAMEL in melanoma patients and is the first report that describes the isolation of tumor Ag-specific CD4(+) Th 2 clones.

Alternative Splicing↗

PubMed1995

[Blood parameters and enzyme values of healthy and sick racing camels (Camelus dromedarius)].

Camel races have a long tradition in Arabia. Since the oil boom of the 1960s a tremendous revival of the old Bedouin tradition of camel racing has occurred in the United Arab Emirates. These camel races are comparable to horse races in Europe and the U.S.A. Since 1985 the most valuable racing camels of Dubai are routinely tested in the Central Veterinary Research Laboratory (CVRL) for their stamina and endurance. Blood and serum enzyme values, which have been statistically ascertained through testing of 10000 healthy racing camels, are now generally accepted as reference values. Besides these check-ups of healthy racing camels, hematological tests, enzyme and substrate estimations are performed on sick racing camels. These tests support the diagnosis, therapy and prognosis of sick camels. In this connection three diseases are discussed: B. cereus intoxication, Clostridium perfringens enterotoxemia and Trypanosomiasis.

Animals↗

PubMed1993

The epidemiology and control of camel dermatophilosis.

Camel dermatophilosis was only recently described. It appears however that it is more widespread than originally thought. In Kenya it has generally been found in the main semi-arid camel rearing areas of Samburu and Laikipia districts although it has not yet been found in the arid areas of Turkana district. In an investigation of ticks on 200 camels, no Amblyomma variegatum ticks were found although many other ticks were present. A. variegatum is suspected to transmit dermatophilosis in many domestic animals. The only control method of dermatophilosis currently practised in Kenya is in one commercial farm, where camels are regularly washed with a 1% potassium aluminium sulphate solution. The camels have shown progressive improvement. Recently, some 50 camels imported from Pakistan in this farm came down with a severe skin infection which closely resembled dermatophilosis. All imported adult camels were involved although no calves were involved. Since no bacteria were isolated from all the sick camels, it was thought to be due to vitamin deficiency.

Actinomycetales Infections↗

PubMed1998

Comparative study of copper and zinc metabolism in cattle and camel.

At an experimental farm, five camels and five cows were fed a similar basal diet for 6 mo. They received oral trace element supplementation for 3 mo (day 22-112). This supplementation included zinc, copper, selenium, manganese, iodine, and cobalt, and corresponded to twice the requirements generally recommended for cows. Plasma copper and zinc concentrations were significantly lower in the camels (61 micrograms/100 mL for copper and 38 micrograms/100 mL for zinc) than in the cows (111 and 83, respectively). The supplementation had no effect on plasma zinc concentration in the camels in spite of the low observed values in this species. Liver copper concentration at the beginning of the trial was lower in the camels (9 ppm) than in the cows (35 ppm), and stayed at lower levels during the entire supplementation period. There was no clear difference in fecal excretion of copper and zinc between the camels and the cows. The results suggested that trace element requirements are lower in camels than in cows and that camels regulate their plasma zinc concentration at a very low level (< 40 micrograms/100 mL).

Animals↗

PubMed1992

The influence of high dietary protein, energy and mineral intake on deficient young camel (Camelus dromedarius)--I. Changes in metabolic profiles and growth performance.

1. The main forage for camels in northern Djibouti (mangrove with Avicennia marina) is very poor in nitrogen and energy. In a trial, 32 young camels (less than 2 years old) were used in four groups of eight each. 2. All the camels received mangrove as basal diet ad lib. 3. After 1 month, the camels received mineral supplementation in copper and zinc (groups 1 and 3) or/and a concentrate rich in protein and energy (groups 2 and 3) or continued with the basal diet (controls). 4. Any supplementation was stopped after 2 months for 1 month. 5. Growth performance was 550 g/day (concentrate-supplemented camels) and 570 g/day (concentrate+mineral-supplemented camels). 6. The growth was negative for the two others groups (-260 g/day). 7. Food intake of mangrove was slightly more important with mineral supplementation only and with mineral+concentrate supplementation. 8. The changes in metabolic profiles have shown an important catabolism in non-supplemented animals, an increase of urea and free fatty acid concentrations in plasma and a decrease of glucose concentrations. 9. Three camels died in the control group with symptoms of starvation and signs of liver damage (increase of liver enzymes glutamate dehydrogenase and gamma-glutamyl transferase).

Animal Feed↗

PubMed1991

Onchocerca fasciata Railliet and Henry, 1910 and its nodule development in camels in Saudi Arabia.

A total of 192 male camels of three age groups (young, adult and old) from Saudi Arabia were examined for Onchocerca fasciata infection by detection of microfilariae in skin snips and nodules in the nuchal ligaments and subcutaneous tissues of the neck and shoulder. The overall prevalence rates were 10.9 and 33.3%, respectively. The prevalence rate by the skin snip technique and the number of microfilariae per gram of skin were higher in young and adult camels than in old camels. However, the prevalence rate by the detection of nodules and the number of nodules per infected camel, increased with increase in age of the camels. An increase in size and weight of nodules was reported with an increase in age of the camels. Nodules varied in diameter from 2 to 36 mm and in weight from 0.5 to 5.0 g. The overall percentage of soft viable and calcified nodules was 42.5 and 57.5%, respectively. The viability of worms decreased, but calcification increased with increased age of the camels. Four levels of degeneration and calcification of worms were described following scanning electron microscopy.

Animals↗

PubMed1994

Metabolism of benzo(a)pyrene, dimethylbenzanthracene and aflatoxin B1 by camel liver microsomes.

The ability of camel liver microsomes to metabolise a range of common environmental carcinogens including benzo(a)pyrene, dimethylbenzanthracene and aflatoxin B1 has been investigated. The camel liver has shown the ability to metabolise benzo(a)pyrene, dimethylbenzanthracene and aflatoxin B1 to a number of metabolites. The major metabolites of benzo(a)pyrene produced by camel liver enzymes were identified as its mono-hydroxy derivatives and suggest that the metabolic detoxification pathways of carcinogen metabolism are predominant in this species. Benzo(a)pyrene metabolising activity in camel liver required NADPH and was inhibited by CO and alpha-naphthoflavone suggesting the involvement of cytochrome P450 in the metabolism of this carcinogen by camel liver. The cytochrome P450-dependent metabolism of carcinogen and other specific substrates such as ethoxyresorufin and ethoxycoumarin, by camel liver enzymes, was about 50% higher than that of rat liver enzymes. The cytochrome P450-dependent metabolism of a variety of carcinogenic and other substrates by camel liver demonstrated that there are multiple forms of cytochrome P450 enzymes involved in the metabolism of a wide array of xenobiotics and pollutants.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2006

Disaccharidase activities in camel small intestine: biochemical investigations of maltase-glucoamylase activity.

Disaccharidases (maltase, cellobiase, lactase, and sucrase), alpha-amylase, and glucoamylase in the camel small intestine were investigated to integrate the enzymatic digestion profile in camel. High activities were detected for maltase and glucoamylase, followed by moderate levels of sucrase and alpha-amylase. Very low activity levels were detected for lactase and cellobiase. Camel intestinal maltase-glucoamylase (MG) was purified by DEAE-Sepharose and Sephacryl S-200 columns. The molecular weight of camel small intestinal MG4 and MG6 were estimated to be 140,000 and 180,000 using Sephacryl S-200. These values were confirmed by SDS-PAGE, where the two enzymes migrated as single subunits. This study encompassed characterization of MGs from camel intestine. The Km values of MG4 and MG6 were estimated to be 13.3 mM and 20 mM maltose, respectively. Substrate specificity for MG4 and MG6 indicated that the two enzymes are maltase-glucoamylases because they catalysed the hydrolysis of maltose and starch with alpha-1,4 and alpha-1,6 glycosidic bonds, but not sucrose with alpha-1,2 glycosidic bond which was hydrolyzed by sucrase-isomaltase. Camel intestinal MG4 and MG6 had the same optimum pH at 7.0 and temperature optimum at 50 degrees C and 40 degrees C, respectively. The two enzymes were stable up to 50 degrees C and 40 degrees C, followed by strong decrease in activity at 60 degrees C and 50 degrees C, respectively. The effect of divalent cations on the activity of camel intestinal MG4 and MG6 was studied. All the examined divalent cations Ca(2+), Mn(2+), Mg(2+), Co(2+) and Fe(3+) had slight effects on the two enzymes except Hg(2+) which had a strong inhibitory effect. The effect of different inhibitors on MG4 and MG6 indicated that the two enzymes had a cysteine residue.

Animals↗

PubMed2004

Flavin-containing monooxygenase activity in camel tissues: comparison with rat and human liver enzymes.

We previously reported the occurrence of multiple forms of drug metabolizing enzymes in camel tissues. In this study, we demonstrated for the first time, flavin-containing monooxygenase (FMO)-dependent metabolism of two model substrates methimazole (MEM) and N,N'-dimethylaniline (DMA) by camel liver, kidney, brain and intestine. FMO-catalyzed metabolism in the microsomes of camel tissues was independent of cytochrome P450 (CYP) activity and exhibited a pH and temperature dependence characteristic of FMO enzymes. Use of inhibitors of CYP activities, SKF525A, octylamine or antibody against NADPH-P450 reductase, did not significantly alter the FMO-dependent substrate metabolism. Using MEM as a model substrate for FMO activity, we show that camel liver has an activity similar to that in rat and human livers. MEM metabolism in extrahepatic tissues in camels was significantly lower (60%-80%) than that in liver. Our results suggest occurrence of FMO in camel tissues, with catalytic properties similar to those in rat and human livers. These results may help in better understanding the effects of pharmacologically and toxicologically active compounds administered to camels.

Adult↗

PubMed2005

Osmotic and diffusive properties of intracellular water in camel erythrocytes: effect of hemoglobin crowdedness.

Camel erythrocytes have exceptional osmotic resistance and is believed to be due to augmented water-binding associated with the high hydrophilicity of camel hemoglobin. In practical terms this means that the proportion of osmotically non-removable water in camel erythrocytes is nearly 3-fold greater than that in human erythrocytes (approximately 65 vs approximately 20%). The relationship between water diffusion and the osmotic characteristics of intracellular water is the subject of this report. The amount of osmotically inactive water is 2-fold greater in camel hemoglobin solution in vitro compared to that of human, but water diffusion does not differ in camel and human hemoglobin solutions. However, the evaluation of water diffusion by magnetic resonance measurements in camel erythrocytes revealed approximately 15% lower apparent diffusion coefficient (ADC) compared with human erythrocytes. When human erythrocytes were dehydrated to the level of camel erythrocytes, their osmotic and water diffusion properties were similar. These results show that a lower ADC is associated with a more pronounced increase in osmotically inactive water fraction. It is proposed that increased hemoglobin hydrophilicity allows not only augmented water-binding, but also a closer hemoglobin packaging in vivo, which in turn is associated with slower ADC and increased osmotic resistance.

Animals↗

PubMed1997

Changes in classical pathway complement activity in dromedary camels experimentally infected with Trypanosoma evansi.

The complement system is known to have important effector functions in immune responses. However, its role in camel trypanosomosis has not been determined. The present study was undertaken to evaluate haemolytic complement activity in Trypanosoma evansi-infected and uninfected camels. Five dromedary camels were experimentally infected with T. evansi and classical pathway haemolytic complement activity was assayed. Parasitaemia and packed cell volume were also monitored. Following infection, classical pathway haemolytic complement showed a slight initial increase (7%) in all the camels. The amounts later dropped as the infection progressed and correlated negatively with parasitaemia. Haemolytic complement recovered following elimination of trypanosomes by treatment with melarsomine. Treatment of uninfected camels had no effect on complement. This study has demonstrated that complement concentration increases in the initial phase of infection followed by a drop as the infection progresses towards chronicity. In addition, the study has shown that activation of the classical complement pathway occurs in camels infected with T. evansi. Complement could therefore be involved in the in vivo control of parasitaemia in dromedary camels infected with T. evansi. Decreased complement levels in this species could lead to immunosuppression, widely reported in animal trypanosomosis.

Animals↗

PubMed2002

A review of camel brucellosis.

We reviewed the literature on camel brucellosis. The seroprevalence of brucellosis in camels appears to follow two distinct patterns: a low (2-5%) prevalence in nomadic or extensively kept camels and a high (8-15%) prevalence in camels kept intensively or semi-intensively. The infection is caused by different biotypes of Brucella abortus and Brucella melitensis. Many gaps exist in the literature on the epidemiology of camel brucellosis. There is no clear policy in any of the camel-keeping countries regarding the control of brucellosis in camels. We suggest whole-herd vaccination in low-prevalence countries and test-and-slaughter followed by vaccination in high-prevalence countries.

Africa↗

PubMed1997

Comparative aspects of glucose tolerance in camels, sheep, and ponies.

The aim of the study was to gain informations about factors responsible for the higher level of plasma glucose in camels as compared to sheep and ponies. An intravenous glucose tolerance test was carried out with four camels, four ponies, and four sheep by infusing 1 mmol glucose per kg body weight intravenously within 3 min. Concentrations of glucose, insulin, and non-esterified fatty acids (NEFA) were estimated in venous plasma samples taken before and within 6 hr after infusion. Basal glucose values were higher in camels (7.1 +/- 0.3 mmol/l) than in ponies (4.2 +/- 0.4 mmol/l) and sheep (3.4 +/- 0.2 mmol/l). The rate of glucose elimination was markedly lower in camels (0.270 +/- 0.018 hr-1) than in sheep (0.804 +/- 0.036 hr-1) and ponies (0.858 +/- 0.084 hr-1). The insulin response after glucose infusion was more pronounced in ponies and sheep than in camels. Concentrations of NEFA in plasma dropped 30 min after the infusion in all species, however, NEFA level decreased slower in camels than in sheep and ponies. It is concluded that the markedly higher plasma concentration of glucose in camels compared to sheep and ponies may be caused by a poorer insulin response and/or a reduced tissue sensitivity to insulin.

Animals↗

PubMed2003

Evaluation of antigen and antibody rapid detection tests for Trypanosoma evansi infection in camels in Kenya.

The card agglutination test for Trypanosoma evansi (CATT/T. evansi) for the detection of antibodies, and Suratex for the detection of circulating antigens were compared in a cross-sectional study involving camels in eastern and central parts of Kenya. Of the 2227 camels screened, 2038 were owned by nomadic pastoralists in T. evansi endemic areas in eastern Kenya. A herd of 86 camels were from a ranch in Mugwoni. In Athi River area, 35 camels belonged to Kenya Trypanosomiasis Research Institute, and 68 were slaughter animals. Diagnostic sensitivity estimates were obtained by testing sera from 51 camels that had been found to be parasitologically positive by the haematocrit centrifugation technique, buffy-coat technique and mouse inoculation. Diagnostic specificity was estimated by testing sera from 35 camels known to be trypanosome-free. Positive and negative predictive values (NPVs) were calculated using a range of prevalence values. The sensitivity of CATT/T. evansi (68.6%) was higher than that of Suratex (58.8%), but not significantly. Both tests had equally high specificity (100%). The overall prevalence was 2.3% (51 out of 2227) by parasite detection, 32.2% (327 out of 1017) by CATT/T. evansi and 19.6% (188 out of 961) by Suratex. Overall, there was a positive association between CATT/T. evansi and Suratex though the strength of association was low (McNemar's test=46.12, P=0.001; kappa=0.26, CI: 0.20-0.33). Parasite prevalence ranged from 0% in several herds to 27.8% in a herd in Isiolo. Prevalence was highest in Isiolo with 2.5% (51 out of 2030) by parasitological detection, 38.8% (321 out of 828) by CATT/T. evansi and 21.9% (169 out of 772) by Suratex. In Mugwoni prevalence was 7 and 18% by CATT/T. evansi and Suratex, respectively, and no parasites were detected. In Athi River Suratex detected 2.9% (3 out of 103) positive while CATT/T. evansi and parasitological methods gave negative results. At prevalence values between 10 and 100%, CATT/T. evansi as well as Suratex had infinitely high positive predictive values, whereas Suratex had a lower NPV than CATT/T. evansi. In conclusion, results of this study showed that CATT/T. evansi and Suratex were able to detect aparasitaemic infections rapidly and were more sensitive than parasitological methods in revealing the true extent of trypanosomosis in a herd. The tests effectively complemented parasitological methods in the detection of T. evansi infections in camels.

Agglutination Tests↗