Presentation on theme: "A Seminar on Taurine Deficiency in Cats Group 10"— Presentation transcript:
1A Seminar on Taurine Deficiency in Cats Group 10 March 3, 2014
2Biochemistry of Taurine Figure 1. Chemical structure of taurineIUPAC name : 2-aminoethanesulfonic acidTaurine is an sulfonic acid containing an amino group, yet it is not an amino acid as it is often called one, because it lacks a carboxyl group.
3Biosynthesis of Taurine MethionineVitTransulfurationCysteaminePhosphopantothenateCysteinCysteaminedioxygenaseCysteinedioxygenase (CDO)HypotaurineCysteine sulfunic acidCysteine sulfinate decarboxylaseCysteine sulfinic acid pathwayHypotaurinedecarboxylaseCysteine sulfinic aciddehydrogenaseTaurineCysteine sulfinate decarboxylaseCysteic acidA dietary deficiency of vitamin B6 shows a depressing effect on taurine biosynthesis.
4Taurine Transport in the Body Taurine transport across cell membraneNa+ - dependent taurine transporterTaurine release from the cell via three mechanismsExocytosis occurs at basal membraneEnergy-dependent transporterCa2+ - dependent transport
5Physiological Function of Taurine systemVisual systemImmune systemRenal systemBile acidconjugationNervoussystemCardiovascular
6Roles of Taurine in Nervous System Taurine acts as a neurotransmitter.- Its ability to elicit neuronal hyperpolarization.- The presence of specific taurine synthesizing enzymes (CSAD), taurine-specific receptor, and a taurine transporter system.Taurine is essential for normal function of central nervous system. Its accumulation varies in location, depends on species and age.Its amount gradually decreases after development.Taurine can be found in majority of brain cells, more concentrated in glial cells than neurons. Astrocytes can accumulate taurine up to 20 mM.CSAD = Cysteine sulfinic acid decarboxylase
7Taurine as a neuroprotective agent. - Cellular injury prevention- Intracellular calcium-ion modulation- Change of anti-apoptotic protein (Bcl-2) and pro-apoptotic protein (Bax) ratio- Autolysis inhibitionTaurine as a neuroprotective agent.
8Roles of Taurine in Cardiovascular System Taurine acts as positive inotropes by promoting calcium-ion release from sarcoplasmic reticulum in cardiac myocytes by modulates calcium transportation during the excitation- contraction coupling.
9Roles of Taurine in Cardiovascular System Excitation-contraction couplingof cardiac myocyte.
10Roles of Taurine in Visual System Taurine is found in high concentration at the retina, particularly in photoreceptor cell bodies of outer nuclear layer.Kittens are more prone to taurine depletion in photoreceptor cells compared to adult cats.
11Photoreceptor cell Phototransduction system outer segment Inner segmentSynaptic terminalPhotoreceptor cellPhototransductionsystem
13Roles of Taurine in Immune System MyeloperoxidaseTaurine can eradicate free radicals generated from specific myeloperoxidase reaction, i.e. hypochlorous acid (HOCl) and hypobromous acid (HOBr), thus it can reduce oxidative stress.Myeloperoxidase enzyme presents in leucocytes as a defense against microbes can generate free radicals which are potentially toxic to host cells.
14Roles of Taurine in Renal System Renal vascular resistanceTaurine aids in renal blood flow regulation.GlomerulusElimination of reactive oxygen species (ROS)Proximal tubuleTaurine affects sodium transportation.Regulation of taurine body pool size.Medullary collecting ductTaurine acts as osmoregulator, thus it can control the cell volume.Taurine may prevent glomerulonephritis, diabetic nephopathy, chronic renal failure, and acute kidney injury (AKI)
15Taurine transport in renal tubular cell Roles of Taurine in Renal SystemTaurine transport in renal tubular cell
16Taurine Deficiency in Cats -Bile conjugation-CSADWhy are cats more likely to develop taurine deficiency?How does taurine deficiency affects cats health?Cats have low activity of cysteine sulfinic acid decarboxylase (CSAD) in the liver, which is essential for taurine biosynthesis.It is obligatory that cats conjugate bile acid solely with taurine, even in the status of taurine depletion.
17Taurochenodeoxycholic acid Bile acid conjugationCholesterol7αHydroxylase7αHydroxyCholesterolCholic acid(primary bile acid)Chenodeoxy(primary bile acid)GlycineTaurineTaurineCats have low activity of cysteine sulfinic acid decarboxylase (CSAD) in the liver, which is essential for taurine biosynthesis.It is obligatory that cats conjugate bile acid solely with taurine, even in the status of taurine depletion.Taurochenodeoxycholic acidGlyconolic acidTaurocholic acidLinthocolic acid(secondary bile acid)
18Taurine Deficiency on Cats Health Cardiac FunctionVisual SystemImmune SystemReproductive System & Development
19Impaired sensitivity of contractile protein to Ca2+ Cardiac FunctionImpaired sensitivity of contractile protein to Ca2+DecreaseCa2+ influxCellApoptosisImpaired systole and diastoleFeline Dilated Cardiomyopathy (DCM)Decrease in calcium influx to cardiac myocytes.Impaired sensitivity of contractile protein to calcium ion.Decrease in number of cardiac myocytes due to apoptosis.Heart failure
20Retina Visual system Lens Tapetum Lucidum Feline central retinal degeneration(FCRD)RetinaTapetum LucidumVisual systemLateral geniculate bodySuperior colliculusLens
23Immune system Leucopenia Decrease respiratory burst of neutrophils Decrease phagocytic activity of phagocytes
24Reproductive System & Development Taurine-deficient pregnant queenKittens born from taurine- deficient female catsMore incidences of fetal death (resorption), abortion, or stillbirth.Reduction of taurine concentration in feline maternal milk.Low survival rateLow birth weightGrowth retardationBone malformationImpaired nervous and visual system development.Kitten obtain taurine from the queenIn other species, the placenta provides the fetus with essential nutrients. The mechanism by which the queen supplied taurine to the kittens in utero was not known. This work was conducted in collaboration with scientists at the University of Manchester (Champion et al. 2004; Champion et al.2005). Taurine uptake was characterised in placental fragments obtained from queens during normal parturition. For the first time, it was shown that the cat placenta possesses amino acid transport systems that are functionally similar to the system β and system A transporters of the human placenta (Champion et al. 2004).
25Kittens born from taurine-deficient female cats. A premature kitten with congenital hydrocephalus.A stillbirth kitten with anencephaly.Severe congenital hydrocephalus, a brain from 1-year old kitten.Kitten obtain taurine from the queenIn other species, the placenta provides the fetus with essential nutrients. The mechanism by which the queen supplied taurine to the kittens in utero was not known. This work was conducted in collaboration with scientists at the University of Manchester (Champion et al. 2004; Champion et al.2005). Taurine uptake was characterised in placental fragments obtained from queens during normal parturition. For the first time, it was shown that the cat placenta possesses amino acid transport systems that are functionally similar to the system β and system A transporters of the human placenta (Champion et al. 2004).
26Effects on digestive physiology Nutritional AspectsRecommended amountCommercial dietsBioavailabilityIngredientsProcessingDry dietEffects on digestive physiologyCanned dietProcessing
27Taurine Requirement for Cats The Association of American Feed Control Officials (AAFCO) Growth and ReproductionAdult MaintenanceNutrientMinimumMaximumTaurine (extrude,%)0.10Taurine (canned,%)0.20AAFCONutrient requirements are indicated on a dry-matter basis. These AAFCO nutrient profiles for cat foods presume an energy density of 4.0 kcal ME/g dry matter.By comparison, the average mature body weight of domestic cats is 3.2 kg (7 lb) for toms and 2.8 kg (6 lb) for queens. Normal birth weight of kittens is 90–100 g. The growth rate is exceptionally rapid for the first 3–4 mo, and kittens gain 50–100 g/wk. The growth rate begins to plateau at 150–160 days of age, and growth is usually completed within 200–220 days.
28How to prevent taurine deficiency in cats? Nutritional AspectsHow to prevent taurine deficiency in cats?Commercial dietsHomemade mealProcessing
29Taurine amount labelled on Hill’s commercial cats diets
31Case study Feline Dilated Cardiomyopathy History takingDomestic male cat, 4 years old, 3.8 kg. body weightSigns of depression, poor appetite, cough, and dyspnea since 3 weeks ago.The cat has muffled cardiac sound.The owner had fed the cat with commercial dog food for 1 year and 6 months.
32ExaminationThoracic radiograph shows severe fluid accumulation in pleural space.Electrocardiography shows decrease in 'R' wave amplitudeEchocardiography shows incress in EDV = End diastolic volume or LVIDd ↓ , ESV = End systolic volume or LVIDs ↓ and shortening fraction ↑Hematology and Serum biochemical parameter are normalDirect opthalmoscopic is normal
33Shortening fraction Measurement Normal LVIDd (cm) 2.45 1.59 ± 0.19 LVISd (cm)2.270.80 ± 0.14∆ D (%)8.549.8 ± 5.3