Determination of free and total cyst(e)ine in plasma of dogs and cats

Tôrres, Cristina L.; Miller, Joshua W.; Rogers, Quinton R.

doi:10.1111/j.1939-165x.2004.tb00378.x

Cited by 23 publications

(22 citation statements)

References 13 publications

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“…In the present study it was unfortunately not possible to meaningful assess the cats’ cyst(e)ine status because the low plasma/serum cyst(e)ine concentrations noted in all cats were likely artefactual, due to cysteine interaction with sulphydryl groups on plasma proteins and subsequent loss when the protein was precipitated during sample preparation. This loss occurs rapidly in feline plasma/serum that is not deproteinised immediately after collection [29]. …”

Section: Discussionmentioning

confidence: 99%

Alterations in amino acid status in cats with feline dysautonomia

McGorum

Symonds

Knottenbelt³

et al. 2017

PLoS ONE

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Feline dysautonomia (FD) is a multiple system neuropathy of unknown aetiology. An apparently identical disease occurs in horses (equine grass sickness, EGS), dogs, rabbits, hares, sheep, alpacas and llamas. Horses with acute EGS have a marked reduction in plasma concentrations of the sulphur amino acids (SAA) cyst(e)ine and methionine, which may reflect exposure to a neurotoxic xenobiotic. The aim of this study was to determine whether FD cats have alterations in amino acid profiles similar to those of EGS horses. Amino acids were quantified in plasma/serum from 14 FD cats, 5 healthy in-contact cats which shared housing and diet with the FD cats, and 6 healthy control cats which were housed separately from FD cats and which received a different diet. The adequacy of amino acids in the cats’ diet was assessed by determining the amino acid content of tinned and dry pelleted foods collected immediately after occurrences of FD. Compared with controls, FD cats had increased concentrations of many essential amino acids, with the exception of methionine which was significantly reduced, and reductions in most non-essential amino acids. In-contact cats also had inadequate methionine status. Artefactual loss of cysteine during analysis precluded assessment of the cyst(e)ine status. Food analysis indicated that the low methionine status was unlikely to be attributable to dietary inadequacy of methionine or cystine. Multi-mycotoxin screening identified low concentrations of several mycotoxins in dry food from all 3 premises. While this indicates fungal contamination of the food, none of these mycotoxins appears to induce the specific clinico-pathologic features which characterise FD and equivalent multiple system neuropathies in other species. Instead, we hypothesise that ingestion of another, as yet unidentified, dietary neurotoxic mycotoxin or xenobiotic, may cause both the characteristic disease pathology and the plasma SAA depletion.

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Section: Discussionmentioning

confidence: 99%

Alterations in amino acid status in cats with feline dysautonomia

McGorum

Symonds

Knottenbelt³

et al. 2017

PLoS ONE

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“…Previous studies have indicated that methionine is susceptible to oxidation during storage [30], whilst cysteine is unstable in storage if samples are not deproteinised by treating with sulphosalicylic acid immediately after sampling [31]. Given that the storage conditions of the current study were not optimized for either amino acid, we were concerned that results would not be reliable and, therefore, chose not to analyse them.…”

Section: Discussionmentioning

confidence: 99%

“…Methionine was not measured because previous studies have demonstrated that this amino acid is susceptible to oxidation during storage [30]. Cysteine was also not measured because this amino acid is susceptible to breakdown if not treated with sulfosalicylic acid immediately after sampling [31]. …”

Section: Methodsmentioning

confidence: 99%

Status of selected nutrients in obese dogs undergoing caloric restriction

et al. 2013

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BackgroundThe purpose of this study was to test the hypothesis that dog plasma concentrations of selected nutrients decrease after undergoing caloric restriction for weight loss. Thirty-one overweight dogs that had successfully lost at least 15% of initial body weight were included in the study. Nutrients that had been previously identified to be at potential risk of deficiency during caloric restriction were measured in plasma (choline, amino acids) and urine (selenium) at the initiation and completion of a standardized weight loss regimen in dogs.ResultsDogs remained healthy throughout the study, and no signs attributable to nutrient deficiency were noted. Percentage weight loss was 28.3% (16.0-40.1%) starting body weight, over a period of 250 days (91–674 days). Median energy intake during the weight loss period was 62 (44 to 74) Kcal/kg0.75 target weight per day. Choline (P = 0.046) and threonine (P = 0.02) decreased after weight loss. Glycine (P = 0.041), and urinary selenium:creatinine ratio (P = 0.006) both increased after weight loss. There were no other significant differences in plasma nutrient concentrations.ConclusionsSince concentrations of most measured nutrients did not change significantly, the data are not consistent with widespread nutrient deficiency in dogs undergoing caloric restriction using a diet formulated for weight loss. However, the significance of the decrease in plasma choline concentration requires further assessment.

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“…The LP diet was made by adding additional fat, pregelatinised starch, minerals and vitamins to a moist commercial diet (which had passed a minimum feeding protocol for proving an adult maintenance claim for a cat food (11) ), in order to reduce the protein content ( Table 1). After a 9 d period during which the animals adapted to the metabolism cages (days 1-9), urine was collected quantitatively for 5 d (days [10][11][12][13][14] and pooled per cat. Thereafter, the cats received the moist HP diet (Table 1) for a further 9 d (days 15-23) before urine was again collected for 5 d (days [24][25][26][27][28] and pooled per cat.…”

Section: Animals and Housingmentioning

confidence: 99%

Urinary felinine excretion in intact male cats is increased by dietary cystine

et al. 2008

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Felinine is a branched-chain sulfur amino acid present in the urine of certain Felidae, including domestic cats. The objective of the present study was to determine if additional cystine and/or dietary N would increase felinine and N-acetylfelinine excretion by intact male cats fed a low-protein (LP) diet. Feeding five adult intact male cats an LP diet (18·8 % of metabolisable energy (ME) as protein) v. a high-protein diet (38·6 % of ME as protein) resulted in a trend (P¼ 0·08) for decreased urinary felinine and no change in N-acetylfelinine excretion. In a 23 d study, when the LP diet was supplemented with L-cystine at 9·3 g/kg DM, urinary felinine:creatinine ratio showed a linear two-fold (121 %) increase (P,0·01) from 0·24 (SEM 0·05) to 0·53 (SEM 0·13) after 10 d. Subsequent feeding of the LP diet resulted in a decrease in felinine excretion to base levels. Plasma gglutamylfelinylglycine concentrations were consistent with the excretion of felinine. Supplementation of the LP diet with L-cystine (9·3 g/kg DM), dispensable amino acids and arginine to a second group (n 5) also resulted in a significant (P,0·01) but smaller (þ 72 %) increase in the daily felinine:creatinine ratio (0·25 (SEM 0·04) to 0·43 (SEM 0·05)). The degree of felinine N-acetylation within groups was unaffected by dietary addition and withdrawal of amino acids. The results indicate that felinine synthesis is regulated by cystine availability, and that arginine may be physiologically important in decreasing felinine biosynthesis in intact male cats. N-acetylfelinine: Arginine: Cats: Cysteine: FelinineFelinine is a unique amino acid excreted by certain species within the Felidae family, including the domestic cat. This sulfur-containing, branched-chain amino acid has been found in concentrations of 3·6 g/l in the urine of intact male cats (Felis catus), with castrated males excreting approximately one-quarter as much as intact males (1) . Synthesis of felinine is believed to occur from glutathione and isopentenylpyrophosphate, through a unique glutathione sulfur transferase enzyme which is under hormonal control (2,3) to form a felinine-containing tripeptide: g-glutamylfelinylglycine or methylbutanolglutathione (MBG). The g-glutamylfelinylglycine is transported in the blood (4) to the kidney where hydrolysis by g-glutamyltransferase present on the surface of the brushborder membrane of proximate tubular cells results in felinylglycine and glutamic acid. The dipeptide can be further hydrolysed to felinine and glycine by either dipeptidase activities or a recently discovered enzyme with carboxylesterase activity (5) . This 70 kDa enzyme (cauxin) has been found in relatively high concentrations in feline urine and has been shown to be able to hydrolyse felinylglycine but not MBG (5) . Following the hydrolysis of felinylglycine, N-acetylation of felinine can occur. This is an intracellular process catalysed by cysteine-S-conjugate N-acetyltransferase and yielding mercapturic acids via the addition of an acetyl group transferred from acetyl-CoA, whi...

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Determination of free and total cyst(e)ine in plasma of dogs and cats

Abstract: These results emphasize the importance of removing plasma proteins within 1 hour after blood collection for reliable assay of free plasma cyst(e)ine.

Cited by 23 publications

References 13 publications

Alterations in amino acid status in cats with feline dysautonomia

Alterations in amino acid status in cats with feline dysautonomia

Status of selected nutrients in obese dogs undergoing caloric restriction

Urinary felinine excretion in intact male cats is increased by dietary cystine

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