Exacerbative effect of vitamin A on malabsorption syndrome in chicks

The interaction between malabsorption syndrome (MAS) and dietary vitamins A and D was studied in broiler chicks reared in floor pens for 4 weeks. The chicks were naturally infected with MAS, whereas hatchmates fed the same diets but in a separate facility (battery brooder) did not exhibit signs of MAS and, therefore, were considered controls. MAS significantly reduced body weights, bone ash, serum calcium and phosphorus concentrations, and liver lipids and increased the incidence of skeletal abnormalities (tibial dyschondroplasia and rickets). Rather than ameliorating the effects of MAS, vitamin A caused a further reduction in body weight and bone ash. A possible nutrient interaction between vitamin A and vitamin D or vitamin E in birds with MAS may account for the exacerbative effect of vitamin A.     

Vitamin D-dependent rickets type 2 in a four-month-old cat

Vitamin D-dependent rickets type 2 in a four-month-old cat A 4-month-old male domestic shorthair cat was examined because of lethargy, vomiting, diarrhea, muscle tremors, and mydriasis. Laboratory evaluation revealed hypocalcemia, hyperphosphatemia, and high intact parathormone and calcitriol concentrations. Findings were compatible with a diagnosis of vitamin D-dependent rickets type 2. Treatment consisted of oral administration of calcium and calcitriol supplements. During the subsequent 18 months, the cat remained clinically normal. Treatment with oral calcium supplements was eventually discontinued, and the cat was able to maintain serum calcium concentrations within reference limits.     

Vitamin D-dependent rickets type II in a cat

A cat with clinical signs Indicating rickets was diagnosed as having a defect of vitamin D receptors. Clinical signs had been seen from four months of age. Treatment with calcium supplementation and various forms of vitamin D did not alter plasma calcium levels or reverse skeletal lesions of lateral antebrachial bowing, lumbar spinal lordosis and costochondral beading. Analgesics were effective for relieving skeletal pain during the bone growth phase and were withdrawn when the animal reached skeletal maturity. Therapy for hip osteoarthritis was given from five years of age until the cat was euthanased at nine years of age as a result of refractory hip pain.     

Rickets caused by excessive renal phosphate loss and apparent abnormal vitamin D metabolism in a cat

Rickets was diagnosed in a 1-year-old cat with a history of weakness, osteopenia, and recurrent fractures. Processes causing rickets include vitamin D deficiency caused by inadequate, nutrition, lack of exposure to sunlight, defective metabolism of parent vitamin D to active metabolites, inherited vitamin D receptor defects, hypoparathyroidism, chronic renal failure, renal loss of phosphate, or malabsorptive states resulting from gastrointestinal or hepatic diseases. On the basis of analysis of serum 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D2 and D3 concentrations, serum biochemical analysis, and urinary fractional clearance of electrolytes, the causes of rickets in our cat, were most compatible with a combination of excessive loss of phosphorus via the kidneys and deficient or abnormal hepatic 25-hydroxylation of vitamin D. Calcifediol treatment and twice daily administration of phosphate salts resulted in clinical improvement and increases in mineralization of the skeleton, as evidenced on radiographic evaluation.     

Rickets in growing pigs and response to treatment

The clinical, radiological and pathological findings in a natural outbreak of rickets affecting 82 pigs are described. An interesting feature was the presence of gross articular abnormalities including resorption of subchondral bone with folding and ulceration of the articular cartilage. The diet was deficient in calcium and vitamin D. A diagnosis of rickets complicated by nutritional secondary hyperparathyroidism was made. The results of treatment and the economics of the outbreak are discussed.     

Cytochrome P450-mediated hepatic metabolism of new fluorescent substrates in cats and dogs

This study aimed to investigate the biotransformation of cat liver microsomes in comparison to dogs and humans using a high throughput method with fluorescent substrates and classical inhibitors specific for certain isozymes of the human cytochrome P450 (CYP) enzyme family. The metabolic activities associated with CYP1A, CYP2B, CYP2C, CYP2D, CYP2E and CYP3A were measured. Cat liver microsomes metabolized all substrates selected for the assessment of cytochrome P450 activity. The activities associated with CYP3A and CYP2B were higher than the activities of the other measured CYPs. Substrate selectivity could be demonstrated by inhibition studies with α-naphthoflavone (CYP1A), tranylcypromine/quercetine (CYP2C), quinidine (CYP2D), diethyldithiocarbamic acid (CYP2E) and ketoconazole (CYP3A) respectively. Other prototypical inhibitors used for characterization of human CYP activities such as furafylline (CYP1A), tranylcypromine (CYP2B) and sulfaphenazole (CYP2C) did not show significant effects in cat and dog liver microsomes. Moreover, IC50-values of cat CYPs differed from dog and human CYPs underlining the interspecies differences. Gender differences were observed in the oxidation of 7-ethoxy-4-trifluoromethylcoumarin (CYP2B) and 3-[2-(N, N-diethyl-N-methylamino)ethyl]-7-methoxy-4-methylcoumarin (CYP2D), which were significantly higher in male cats than in females. Conversely, oxidation of the substrates dibenzylfluorescein (CYP2C) and 7-methoxy-4-trifluoromethylcoumarin (CYP2E) showed significant higher activities in females than in male cats. Overall CYP-activities in cat liver microsomes were lower than in those from dogs or humans, except for CYP2B. The presented difference between feline and canine CYP-activities are useful to establish dose corrections for feline patients of intensively metabolized drugs licensed for dogs or humans.     

Successful therapy of vitamin D-dependant rickets in a kitten

A 7 mo old, 2.4 kg, intact female kitten was evaluated for an inability to walk after falling out of the owner's arms. Diagnostic testing abnormalities included hypocalcemia, low ionized calcium, and elevated intact parathyroid hormone concentration. The 25-hydroxyvitamin D level was normal. Radiographic abnormalities included generalized osteopenia, a nondisplaced, folding fracture of the proximal right fibula, and sclerosis with a compression fracture of the proximal right tibia. Based on these findings and response to calcium carbonate and calcitriol therapy, a diagnosis of vitamin D-dependent rickets was made. Reports of similar cases in veterinary medicine are sparse and no other reports to date document radiographic abnormalities with a successful therapeutic outcome.     

Rickets in turkey poults

Fifteen outbreaks of rickets were diagnosed in turkey poults in Saskatchewan between 1978 and 1981. No relationship to farm, source of poults, or source of feed was apparent. Most outbreaks started when the poults were between 10 and 14 days of age, and they had recovered by 28 days of age. Losses varied from 1% to 14% of poults started. Skeletal lesions were characteristic of a vitamin D or calcium deficiency. On the basis of chemical analyses, adequate levels of calcium and phosphorus and proper amounts of vitamin premixes were present in the feed, but in five outbreaks biological feed tests implicated feed as a causative factor. The severity of rickets in poults fed defective feeds was markedly reduced by providing the poults with extra vitamin D in the drinking water or by injection. Two premixes used in different feeds contained adequate available vitamin D on the basis of biological testing. In some of the outbreaks, the rickets may have resulted from inadequate distribution of vitamin D in the feed, destruction of vitamin D during feed processing, or some unknown factor in the feed interfering with vitamin D utilization.     

Avian tibial dyschondroplasia: a comparison of the incidence and severity as assessed by gross examination and histopathology.

The assessment of avian tibial dyschondroplasia (TD) in many recent studies is based on examination of slices of the proximal tibiotarsus with the naked eye. This study examines the incidence and severity of TD in broilers under four different dietary regimes and compares the efficacy of naked eye assessment with histopathological examination. The diets contained reduced levels of calcium relative to phosphorus with adequate (diet 1) and high (diet 2) levels of vitamin D3 supplementation; a very low calcium diet (diet 3) and a standard diet (diet 4) were also included. Gross examination suggested that TD was present in 80 per cent, 79 per cent and 27 per cent of tibiotarsi from birds on diets 1, 2 and 4, respectively. However, histological examination indicated TD, correspondingly, to be present in 18 per cent, 39 per cent and 6 per cent of tibiotarsi. Some birds on diet 1 exhibited physeal changes consistent with mild hypocalcaemic rickets. Many of the bone extremities which, grossly, were considered dyschondroplastic (diets 1, 2 and 4), histologically were shown to have an extensive hypertrophied zone with poor metaphyseal vessel penetration, but no cellular or matrix changes consistent with TD. This cast doubt on the validity of earlier studies of TD which relied solely on naked eye examination. The birds on diet 3 all demonstrated histopathology considered consistent with severe hypocalcaemic rickets and the present study suggests that in three-week-old broilers a moderately hypocalcaemic diet with a high level of vitamin D3 will not cause rickets but will increase the incidence and severity of TD.(ABSTRACT TRUNCATED AT 250 WORDS)     

Finding the mutation responsible for inherited rickets in Corriedale sheep

Inherited rickets of Corriedale sheep is of simple autosomal recessive inheritance. The gross and histological lesions include segmental thickening of physes, persistence of hypertrophic chondrocytes at sites of endochondral ossification, excessive osteoclastic resorption, microfractures and wide unmineralised osteoid seams lining trabeculae and filling secondary osteons. Initial testing revealed concentrations of 25-hydroxyvitamin D₃ were normal, but those of 1,25-dihydroxyvitamin D₃ were increased in serum of affected sheep, suggesting a defect in the vitamin D receptor. However, in vitro studies on cultured skin fibroblasts revealed normal binding and function of the vitamin D receptor.

A genome-wide association study was conducted using the Illumina OvineSNP50 BeadChip. A homozygous region of 199 consecutive single-nucleotide polymorphism loci was identified in affected sheep, covering a region of 10 megabase pairs on ovine chromosome 6. Of the 91 candidate genes in this region, dentin matrix protein 1 gene (dmp1) was considered the most likely as it is known to play critical roles in osteocyte maturation and mineral metabolism. Sequencing of DNA from carriers showed a nonsense mutation 253T/C in dmp1. This T/C transition introduced a stop codon (R145X) that could truncate C-terminal amino acids. Using PCR restriction fragment length polymorphism for this mutation, genotyping showed that all affected sheep were “TT” genotypes, and phenotypically normal sheep were either “CT” or “CC”. These findings suggest that a mutation in dmp1 is responsible for inherited rickets of Corriedale sheep. A simple diagnostic test is currently being designed to identify carriers with the defective “T” alleles.     

内毒素致兔线粒体DNA基因突变的SSCP检测

将20只健康实验用白兔随机分为4组（5只／组）：正常对照组（A组）、阳离子A处理组（B组）、内毒素处理组（C组）、阳离子A＋内毒素处理组（D组），运用改进的碱变性法提取肝细胞的线粒体DNA（mitochondrial DNA，mtDNA），设计4对引物扩增mtDNA的tRNA^Leu（UUR）、tRNA^Lys、ATPase8、ATPase6基因，同时运用分光光度计法对扩增产物进行质量鉴定，并运用聚合酶链式反应-单链构象多态性分析技术对PCR产物进行突变分析。结果发现：c组tRNA^Leu（UUR）基因在凝胶中的带型出现泳动异常，表明该基因发生了碱基突变，序列测定表明该突变为2716位的A—G点突变，同时其他各组的tRNA^Leu（UUR）基因无突变发生。该结果提示内毒素可以导致mtDNA的tRNA^Leu（UUR）基因发生突变，而阳离子A对这一突变具有保护效应。     

Altered vitamin D metabolic system in follicular cysts of sows

This study aimed to examine 25OHD₃ concentration in the fluid of follicular and follicular lutein cysts of sows in comparison with preovulatory follicles as well as immunolocalize vitamin D metabolic enzymes (CYP27B1 and CYP24A1) and determine their protein abundances in the cyst wall. We have shown for the first time that 25OHD₃ level in the fluid of both cyst types was significantly lower than in preovulatory follicles. Furthermore, we have demonstrated CYP27B1 and CYP24A1 protein immunolocalization and abundance in follicular and follicular lutein cysts. The abundance of protein for both metabolic enzymes was decreased in ovarian cysts when compared to preovulatory follicles. We propose that altered VD metabolism in ovarian cyst might associate with their formation in sows.     

Suspected inherited rickets in Corriedale sheep

A suspected inherited form of rickets was diagnosed in Corriedale sheep on a commercial sheep farm in Marlborough. Affected lambs were normal at birth but showed a reduced growth rate and a range of skeletal abnormalities, including both varus and valgus deformities and a characteristic dip in the shoulder region. Up to 20 affected lambs had been born on the property over the last two seasons. Skeletal lesions in affected lambs included swollen costochondral junctions, moderate to marked thickening of physes in long bones, and collapse of weakened subchondral bone, particularly in the proximal humerus. These lesions, together with the microscopic changes, strongly suggested a diagnosis of rickets. Affected lambs were hypocalcaemic and hypophosphataemic, consistent with a deficiency of vitamin D.

Vitamin D assays revealed significantly higher 1,25(OH) vitamin D concentrations in affected lambs than in controls, suggesting a defect in the vitamin D receptor as the likely mechanism. DNA testing revealed that 4/10 Corriedale rams used during the previous season had sired affected lambs. Studies aimed at confirming the genetic nature of the disease and the mechanism are continuing at Massey University.     

牛孕激素受体SNP分析及其与精液品质的关系

孕激素受体(PR)对于正常雌性动物生殖功能的实现具有重要调节作用,该基因在雄性动物中生物学作用尚不十分清楚。本研究通过PCR-SSCP方法对种公牛群体的PR基因所有外显子及5′UTR多态性进行检测。结果表明:PR基因外显子4、外显子8及5′UTR均检测到了多态性位点,其他外显子没有发现遗传多态性;测序表明外显子4发生了A20G突变,没有导致氨基酸的改变,外显子8发生G86T和A207T突变,其中G86T突变导致所编码的G(甘氨酸)变成V(缬氨酸),A207T突变导致所编码的Q(谷氨酰胺)变成H(组氨酸),5′UTR处存在G-1809A和C-1808G碱基突变。最后用最小二乘分析方法对其基因型和生产性状进行了相关性分析,第4及第8外显子的遗传多态性与部分精液品质性状呈显著相关。     

Abnormal coagulation factor VIII transcript in a Tennessee Walking Horse colt with hemophilia A

Hemophilia A is an X‐chromosome‐linked disorder caused by a deficiency in factor VIII (FVIII). Although foals have been diagnosed with hemophilia A based on deficiency in FVIII activity, causative gene mutations have not been identified. The genomic DNA and cDNA encoding FVIII of a Tennesee Walking Horse colt affected with hemophilia A and the genomic DNA of his dam and a normal unrelated horse were analyzed with no splice site or coding sequence abnormalities identified in any of the horses. Polymerase chain reactions (PCR) were then performed on hepatic cDNA from the affected colt and an unrelated normal horse, and no product was obtained for the sequence between and including exon 1 and exon 2 in the affected colt. Based on these results, suspected mutations were identified in the noncoding region of FVIII (intron 1), and genomic sequencing of intron 1 in the dam and the affected colt suggested maternal inheritance.     

伊犁马MyoG基因外显子1多态性与肉质性状及肌纤维性状关联分析

为寻找伊犁马肉质性能的分子标记,试验以38匹伊犁马为材料,测定肉质性状（失水率、熟肉率、剪切力）和肌纤维性状（肌纤维横截面积、肌纤维直径、肌纤维密度）,利用PCR直接测序法检测肌细胞生成素（meyogenin,MyoG）基因外显子1在伊犁马群体中的多态性,并对MyoG基因SNPs不同基因型与肉质、肌纤维性状进行关联分析。结果表明,MyoG基因外显子1检测出5个突变位点,分别为SNP1（g.31187343 A>C）、SNP2（g.31187333 G>A）、SNP3（g.31187132 C>T）、SNP4（g.31187105 C>G）和SNP5（g.31187099 C>T）,其中SNP1为错义突变,碱基A突变为C使得氨基酸由苏氨酸突变为脯氨酸,其他位点均为无义突变。SNP3和SNP4为中度多态位点,SNP1和SNP2为低度多态位点,这4个位点均处于Hardy-Weinberg平衡状态。MyoG基因外显子1中SNP1和SNP4不同基因型个体失水率、熟肉率、肌纤维横截面积、肌纤维直径、肌纤维密度差异显著（P<0.05）;SNP3不同基因型个体熟肉率、肌纤维横截面积、肌纤维密度差异显著（P<0.05）;SNP2不同基因型个体各指标差异均不显著（P>0.05）。综上,伊犁马MyoG基因外显子1检测到5个多态位点,其中SNP1（g.31187343 A>C）、SNP3（g.31187132 C>T）和SNP4（g.31187105 C>G）位点不同基因型对肉质及肌纤维性状有显著影响,这些位点可作为伊犁马肉质性能潜在分子标记。     

绵羊催乳素受体基因外显子10的多态性分析

将催乳素受体(prolactin receptor, PRLR)基因作为绵羊高繁殖力的候选基因,对其外显子10设计2对引物, 采用PCR SSCP 技术检测其在常年发情的湖羊及季节性发情的中国美利奴羊、罗米丽羊和罗米丽×中国美利奴（新疆军垦型）中的单核苷酸多态性。结果表明,引物P1、P2 的扩增片段均有多态性。与已知序列相比,P1扩增片段的AB型在第53 bp处出现A→G突变、在81 bp处出现G→A突变, BB型在该片段第53 bp处发生A→G的突变;对于P2扩增片段, CC、DD、CE和EF型均在第89 bp处发生C→T的突变,导致氨基酸由脯氨酸变为亮氨酸(Pro→Leu),DD型还在146 bp处出现了C→G的突变,此突变导致氨基酸由丙氨酸变为甘氨酸(Ala→Gly);CE型在该片段第132 bp处发生G→A的突变,未导致氨基酸的改变;EF型还在第132 bp处和第167 bp处分别发生了G→A、C→T突变,第167 bp处的突变导致氨基酸由脯氨酸变为亮氨酸(Pro→Leu)。通过卡方独立性检验结果发现,4种绵羊在P1、P2引物扩增片段上各基因型的构成与品种间有极显著差异(P<0.01),说明PRLR基因对绵羊的繁殖性状有一定的影响。     

Management and prevention of vitamin D deficiency rickets in captive-born juvenile chimpanzees (Pan troglodytes).

Vitamin D deficiency rickets was diagnosed in three juvenile chimpanzees (Pan troglodytes) raised indoors under skylights and consuming only breast milk. Two cases detected early had mild but characteristic radiographic changes. More advanced disease presented with florid x-ray features of rickets and pathologic fractures, as well as hypocalcemia, hypophosphatemia, and low serum 25-hydroxyvitamin D levels. Treatment by a single injection of vitamin D2 in sesame oil (slow release) followed by daily oral supplementation with vitamin D2 corrected the condition. On the basis of experience with these cases and comparison with rickets in humans, a prevention protocol for mother-reared, inside-housed, chimpanzee juveniles was developed. Injection with slow release vitamin D2 (5,000 IU i.m. once) at 4 mo of age, followed by oral supplementation of 400 IU vitamin D2 daily until weaning, prevents rickets in juvenile chimpanzees raised indoors.     

Clinical,metabolic, and genetic characterization of hereditary methemoglobinemia caused by cytochrome b5 reductase deficiency in cats

Two non‐pedigreed male castrated cats had persistent cyanosis over a 3‐year observation period. Clinical cardiopulmonary evaluations did not reveal abnormalities, but the blood remained dark after exposure to air. Erythrocytic methemoglobin concentrations were high (~40% of hemoglobin) and cytochrome b₅ reductase (CYB5R) activities in erythrocytes were low (≤15% of control). One cat remained intolerant of exertion, and the other cat developed anemia and died due to an unidentified comorbidity. Whole‐genome sequencing revealed a homozygous c.625G>A missense variant (B4:137967506) and a c.232‐1G>C splice acceptor variant (B4:137970815) in CYB5R3, respectively, which were absent in 193 unaffected additional cats. The p.Gly209Ser missense variant likely disrupts a nicotinamide adenine dinucleotide (NADH)‐binding domain, while the splicing error occurs at the acceptor site for exon 4, which likely affects downstream translation of the protein. The 2 novel CYB5R3 variants were associated with methemoglobinemia using clinical, biochemical, genomics, and in silico protein studies. The variant prevalence is unknown in the cat population.     

兴义鸭肌肉生长抑制素基因多态性与屠宰性状的相关性分析

为了解兴义鸭肌肉生长抑制素(myostatin,MSTN)基因SNPs与屠宰性状的相关性,本研究采用基因克隆及PCR产物直接测序的方法,将MSTN基因作为鸭屠宰性状的候选基因,对兴义鸭的MSTN基因外显子进行多态性检测.结果表明,在60个兴义鸭个体中筛选出8个SNPs,其中,第1外显子有5个突变位点:SNP1(G77A)、SNP2(A91G)、SNP3(G130A)、SNP4(C325T)和SNP5(C331T);在第2外显子中并未发现突变位点;第3外显子有3个突变位点:SNP6(C206T)、SNP7(A235G)和SNP8(C256A);对这8个SNPs与屠宰性状进行关联性分析,结果并未达到显著水平(P>0.05).本研究结果可丰富MSTN基因的研究数据,为鸭的育种提供参考.