Alpha-amylase gene transcription in tissues of normal dog

Glycemic, insulinemic and methylglyoxal postprandial responses to starches alone or in whole diets in dogs versus cats: Relating the concept of glycemic index to metabolic responses and gene expression

Species differences between domestic cats (Felis catus) and dogs (Canis familiaris) has led to differences in their ability to digest, absorb and metabolize carbohydrates through poorly characterized mechanisms. The current study aimed to first examine biopsied small intestine, pancreas, liver and skeletal muscle from laboratory beagles and domestic cats for mRNA expression of key enzymes involved in starch digestion (amylase), glucose transport (sodium-dependent SGLTs and -independent glucose transporters, GLUT) and glucose metabolism (hexokinase and glucokinase). Cats had lower mRNA expression of most genes examined in almost all tissues compared to dogs (p < 0.05). Next, postprandial glucose, insulin, methylglyoxal (a toxic glucose metabolite) and d-lactate (metabolite of methylglyoxal) after single feedings of different starch sources were tested in fasted dogs and cats. After feeding pure glucose, peak postprandial blood glucose and methylglyoxal were surprisingly similar between dogs and cats, except cats had a longer time to peak and a greater area under the curve consistent with lower glycolytic enzyme expression. After feeding starches or whole diets to dogs, postprandial glycemic response, glycemic index, insulin, methylglyoxal and d-lactate followed reported glycemic index trends in humans. In contrast, cats showed very low to negligible postprandial glycemic responses and low insulin after feeding different starch sources, but not whole diets, with no relationship to methylglyoxal or d-lactate. Thus, the concept of glycemic index appears valid in dogs, but not cats. Differences in amylase, glucose transporters, and glycolytic enzymes are consistent with species differences in starch and glucose handling between cats and dogs.

Effect of tetrastarch (hydroxyethyl starch 130/0.4) on plasma creatinine concentration in cats: a retrospective analysis (2010-2015)

Objectives The objective was to determine survival and changes in creatinine concentrations after administration of 6% tetrastarch (hydroxyethyl starch [HES] 130/0.4) vs crystalloids in critically ill cats. Methods The medical records were reviewed for cats admitted to the intensive care unit with at least two plasma creatinine measurements and initial concentrations not exceeding the upper reference interval. Cats were excluded if they had received HES prior to admission or if they had received fluid therapy for <24 h between initial and subsequent measurements. Changes in creatinine concentrations were evaluated as the percentage change from initial values to the maximum subsequent measurements. Cats receiving only crystalloids were assigned to the crystalloid group; cats receiving only HES or HES and crystalloids were assigned to the HES group. Results Ninety-three cats were included in the study (62 in the crystalloid group, 31 in the HES group). The total median cumulative HES dose was 94 ml/kg (range 26-422 ml/kg) and 24 ml/kg/day (range 16-42 ml/kg/day). No difference was detected between the groups for age, sex, body weight or mortality. The HES group had a significantly longer length of hospitalisation ( P = 0.012), lower albumin concentrations ( P <0.001), higher Acute Patient Physiologic and Laboratory Evaluation scores ( P = 0.037) and higher incidence of systemic inflammatory response syndrome ( P = 0.009) and sepsis ( P = 0.013). There was no significant difference in initial, maximum or maximum change in creatinine concentrations between the groups. Moreover, there was no significant difference in maximum change in creatinine concentrations in the subgroups of cats with systemic inflammatory response syndrome or sepsis. Conclusions and relevance In this population of cats, the administration of HES did not result in a significantly greater increase in creatinine from values measured on admission or higher mortality compared with administration of crystalloids. Further prospective studies are needed to assess both safety and efficacy of HES in cats before recommendations can be made.

Canine Salivary Glands: Analysis of Rab and SNARE Protein Expression and SNARE Complex Formation With Diverse Tissue Properties

The comparative structure and expression of salivary components and vesicular transport proteins in the canine major salivary glands were investigated. Histochemical analysis revealed that the morphology of the five major salivary glands-parotid, submandibular, polystomatic sublingual, monostomatic sublingual, and zygomatic glands-was greatly diverse. Immunoblot analysis revealed that expression levels of α-amylase and antimicrobial proteins, such as lysozyme, lactoperoxidase, and lactoferrin, differed among the different glands. Similarly, Rab proteins (Rab3d, Rab11a, Rab11b, Rab27a, and Rab27b) and soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor (SNARE) proteins VAMP4, VAMP8, syntaxin-2, syntaxin-3, syntaxin-4, and syntaxin-6 were expressed at various levels in individual glands. mmunohistochemistry of Rab3d, Rab11b, Rab27b, VAMP4, VAMP8, syntaxin-4, and syntaxin-6 revealed their predominant expression in serous acinar cells, demilunes, and ductal cells. The VAMP4/syntaxin-6 SNARE complex, which is thought to be involved in the maturation of secretory granules in the Golgi field, was found more predominantly in the monostomatic sublingual gland than in the parotid gland. These results suggest that protein expression profiles in canine salivary glands differ among individual glands and reflect the properties of their specialized functions.

Rapid exacerbation of renal function after administration of hydroxyethyl starch in a dog

Hydroxyethyl starches (HES) are commonly used synthetic colloidal solution in veterinary medicine. Despite of possible adverse effect to kidney injury in human, there is no report about nephrotoxic effects of HES in dogs. HES was administered to a Golden retriever (4-year-old, intact male) with ascites in order to increase plasma osmolality. Initially, the dog was mild azotemic, however, kidney function was rapidly deteriorated after several days of HES administration. Finally, histopathological examination revealed remarkable osmotic nephrosis. In the case reported herein, acute kidney injury was remarkably developed after HES administration. Clinical and histopathologic findings of acute kidney injury support nephrotoxic effects of HES to a dog.

Retrospective evaluation of the effects of administration of tetrastarch (hydroxyethyl starch 130/0.4) on plasma creatinine concentration in dogs (2010-2013): 201 dogs

OBJECTIVE

To determine changes in creatinine concentrations following the administration of 6% tetrastarch (hydroxyethyl starch [HES] 130/0.4) compared to crystalloids (CRYSs) in critically ill dogs.

DESIGN

Retrospective case series (2010-2013).

SETTING

University teaching hospital.

ANIMALS

Two hundred and one dogs admitted to the intensive care unit with initial plasma creatinine concentrations not exceeding laboratory reference intervals (52-117 μmol/L [0.6-1.3 mg/dL]) and receiving either CRYSs alone (CRYS group, n = 115) or HES with or without CRYSs (HES group, n = 86) for at least 24 hours.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Creatinine concentrations at admission to the intensive care unit (T0), and 2-13 days (T1) and 2-12 weeks (T2) after initiation of fluid therapy were analyzed. Creatinine concentrations were analyzed as absolute values and as the maximum percentage change from T0 to T1 (T1max%) and from T0 to T2 (T2max%), respectively. Creatinine concentrations were available for 192 dogs during T1 and 37 dogs during T2. The median cumulative dose of HES was 86 mL/kg (range, 12-336 mL/kg). No difference was detected between the groups for age, gender, body weight, and length of hospitalization. Outcome was significantly different between the HES (66% survived) and the CRYS (87% survived) groups (P = 0.014). No significant difference was detected between groups for creatinine concentrations at T0, T1, T2, T1max%, or T2max%. No significant difference was detected between the groups for T1max% creatinine in dogs subclassified as having systemic inflammatory response syndrome or sepsis.

CONCLUSIONS

HES administration in this canine population did not result in increased creatinine concentrations compared to administration of CRYSs. Further studies are needed to establish the safety of HES in critically ill dogs.

Controversies in the use of hydroxyethyl starch solutions in small animal emergency and critical care

OBJECTIVES

To (1) review the development and medical applications of hydroxyethyl starch (HES) solutions with particular emphasis on its physiochemical properties; (2) critically appraise the available evidence in human and veterinary medicine, and (3) evaluate the potential risks and benefits associated with their use in critically ill small animals.

DATA SOURCES

Human and veterinary original research articles, scientific reviews, and textbook sources from 1950 to the present.

HUMAN DATA SYNTHESIS

HES solutions have been used extensively in people for over 30 years and ever since its introduction there has been a great deal of debate over its safety and efficacy. Recently, results of seminal trials and meta-analyses showing increased risks related to kidney dysfunction and mortality in septic and critically ill patients, have led to the restriction of HES use in these patient populations by European regulatory authorities. Although the initial ban on the use of HES in Europe has been eased, proof regarding the benefits and safety profile of HES in trauma and surgical patient populations has been requested by these same European regulatory authorities.

VETERINARY DATA SYNTHESIS

The veterinary literature is limited mostly to experimental studies and clinical investigations with small populations of patients with short-term end points and there is insufficient evidence to generate recommendations.

CONCLUSIONS

Currently, there are no consensus recommendations regarding the use of HES in veterinary medicine. Veterinarians and institutions affected by the HES restrictions have had to critically reassess the risks and benefits related to HES usage based on the available information and sometimes adapt their procedures and policies based on their reassessment. Meanwhile, large, prospective, randomized veterinary studies evaluating HES use are needed to achieve relevant levels of evidence to enable formulation of specific veterinary guidelines.

Amylase activity is associated with AMY2B copy numbers in dog: implications for dog domestication, diet and diabetes

High amylase activity in dogs is associated with a drastic increase in copy numbers of the gene coding for pancreatic amylase, AMY2B, that likely allowed dogs to thrive on a relatively starch-rich diet during early dog domestication. Although most dogs thus probably digest starch more efficiently than do wolves, AMY2B copy numbers vary widely within the dog population, and it is not clear how this variation affects the individual ability to handle starch nor how it affects dog health. In humans, copy numbers of the gene coding for salivary amylase, AMY1, correlate with both salivary amylase levels and enzyme activity, and high amylase activity is related to improved glycemic homeostasis and lower frequencies of metabolic syndrome. Here, we investigate the relationship between AMY2B copy numbers and serum amylase activity in dogs and show that amylase activity correlates with AMY2B copy numbers. We then describe how AMY2B copy numbers vary in individuals from 20 dog breeds and find strong breed-dependent patterns, indicating that the ability to digest starch varies both at the breed and individual level. Finally, to test whether AMY2B copy number is strongly associated with the risk of developing diabetes mellitus, we compare copy numbers in cases and controls as well as in breeds with varying diabetes susceptibility. Although we see no such association here, future studies using larger cohorts are needed before excluding a possible link between AMY2B and diabetes mellitus.

Amylase α-1A (AMY1A): a novel immunohistochemical marker to differentiate chromophobe renal cell carcinoma from benign oncocytoma

Chromophobe renal cell carcinoma (ChRCC) and oncocytoma present with a perplexing overlap of morphologic and immunohistochemical features. ChRCC have deletions in the 1p21.1 region including the amylase α-1A gene (AMY1A). No such deletions are found in oncocytoma. Instead, oncocytomas shared other deletions on chromosome 1: 1p31.3, 1q25.2, and 1q44. We performed AMY1A immunostaining on 75 oncocytomas (57 tissue microarray [TMA] cores, 18 whole slides) and 54 ChRCCs (20 TMA cores, 34 whole slides). Staining was assessed using the H-score method. The intensity was graded as follows: no staining=0, weak=1, moderate=2, and strong=3. The AMY1A immunostain preferentially stained the distal tubules and collecting ducts of normal kidney. All oncocytomas (100%) expressed AMY1A with an H-score that varied from 100 to 300 (mean 205). Mild to moderate heterogeneity in staining intensity was noted within a given oncocytoma. For oncocytomas, 87% (65/75) cases had H-scores of at least 120 with a mean score of 221. Notably, the 13% (10/75) of oncocytoma cases that had an H-score of 100 were derived from the TMA. A total of 87% (47/54) of the ChRCC cases were negative for the AMY1A immunostain. Of the ChRCC cases, 4% (2/54) showed very weak cytoplasmic staining (H-score of 70 each), which was less than the lowest H-score of oncocytoma cases. All 5 cases of ChRCC, which showed an H-score of 100 or more, were referred to as eosinophilic variants of ChRCC. Three of these 5 cases showed a very nondescript, diffuse staining of the cytoplasm. Two of these 5 cases showed an H-score of 130. We think that as the staining pattern of these 2 cases is similar to that of oncocytoma, they should be put in a category of renal oncocytic neoplasms favoring oncocytoma. This result shows that AMY1A staining could be very helpful in further classifying even a subset of the eosinophilic variants of ChRCC. The difference between ChRCC and oncocytoma was statistically significant (χ test, P<0.0001). All cases of clear cell RCC and papillary RCC were negative for AMY1A expression. Overall, sensitivity and specificity of AMY1A staining for oncocytoma was 100% (95% confidence interval, 0.95-1.00) and 96.75% (95% confidence interval, 0.93-0.99), respectively. Similarly, the sensitivity and specificity for distinguishing oncocytoma from ChRCC was 100% (95% confidence interval, 0.95-1.00) and 90.74% (95% confidence interval, 0.80-0.97), respectively. These data show that the novel marker AMY1A can be of great diagnostic utility when trying to differentiate ChRCC (classic and eosinophilic variant) and oncocytoma.

In situ reverse transcription: the magic of strength and anonymity

In this study, we describe an approach that enables a highly specific, effective and fast detection of polyadenylated RNA sequences in situ at the light and electron microscopy levels. The method developed is based on the incorporation of 5-bromo-2′-deoxyuridine into the growing cDNA strand by means of the reverse transcriptase. We have shown that unlike the previously used deoxyuridine tagged with biotin or digoxigenin, 5-bromo-2′-deoxyuridine is ‘invisible’ in the DNA–DNA duplex but easily detectable in the DNA–RNA duplex. This feature is an important pre-requisite for the correct interpretation of the data obtained, as our results strongly indicate that reverse transcriptase uses DNA breaks as primers efficiently. We have also shown that the replacement of deoxythymidine by 5-bromo-2′-deoxyuridine considerably stabilizes the growing DNA–RNA duplex, thus enabling the one-step detection of polyadenylated RNA in structurally well-preserved cells. The method developed provides a highly specific signal with the signal/noise ratio higher than 130 for permeabilized cells and 25 for conventional acrylic resin sections under the conditions used. When the high pressure freezing technique followed by the freeze substitution is employed for the cell's preparation, the ratio is higher than 80.

Implication of Reg I in human pancreatic duct-like cells in vivo in the pathological pancreas and in vitro during exocrine dedifferentiation

A feature associated frequently with the pathologic pancreas is the presence of tubular complexes produced by a phenotypic modulation of acinar cells that take on the characteristics of ductular cells. Since the type I Reg gene, an acinar cell product, is increased in the pancreas following an acinar injury, we aimed to evaluate whether the Reg I protein might be involved in this dedifferentiation process in the human pancreas. We studied duct-like structures in fixed human pathologic pancreatic tissues and human cells with a ductal phenotype obtained by culturing human exocrine preparations. Immunocytochemistry, Western blotting, and RT-PCR were applied for detection of type I Reg. Reg I was observed not only in acinar cells but also in the duct-like cells and dilated duct cells, both positive for cytokeratin 19. However, none of the other acinar markers was observed in these cells. In vitro, human acinar cells dedifferentiated, losing their acinar phenotype, but expression of Reg I remained constant throughout the culture duration. Furthermore, Reg I was not associated with proliferation. We demonstrated that Reg I expression was linked to acinar cell dedifferentiation. We postulate that Reg I might be used as a marker to understand the events leading to phenotypic changes of acinar cells to address the physiological role of Reg I in the pancreas.

Preferential expression of reg I beta gene in human adult pancreas

In human pancreas two genes, reg I alpha and reg I beta, have been characterized but only the reg I alpha protein has been isolated from human pancreatic secretion. To examine their respective physiological roles in fetal and adult pancreas we have compared the patterns of gene expression using a specific RT-PCR method. No progressive evolution in the two mRNAs levels was observed during fetal development (16--41 weeks). A discoordinate expression of the two genes was found with a higher level of reg I alpha mRNA in fetus and a higher level of regI beta in adult. In addition, if reg I alpha mRNA level was correlated with the expression of genes encoding exocrine proteins in adults, reg I beta mRNA level presented no correlation with any ductular, endocrine, or exocrine gene expression. In human pancreatic cell lines we showed the only expression of reg I beta gene and protein. All these data suggest that the two reg genes and proteins could play different roles in the pancreas.

Cloning and expression of a chicken alpha-amylase gene

We have isolated and sequenced a genomic clone for a pancreatic alpha-amylase gene (amy) of the chicken (Gallus gallus). The gene is interrupted by nine introns, spans over 4 kb, and encodes a protein (AMY) of 512 aa that is 83% identical to the human pancreatic alpha-amylase enzyme. Southern blot analysis of chicken DNA revealed two distinct pancreatic amy loci. In addition, we have generated a cDNA from chicken pancreatic RNA corresponding to the coding sequence of the genomic clone. The cDNA was inserted into a yeast expression vector, and the resulting construct used to transform Saccharomyces cerevisiae cells. Transformed yeast cells synthesized and secreted active AMY enzyme, and the gel migration pattern of the alpha-amylase produced by the yeast cells was identical to that of the native chicken enzyme.

Emergence in human dental plaque and host distribution of amylase-binding streptococci

Salivary amylase is known to bind specifically to several species of oral streptococci. To assess the importance of this interaction in bacterial colonization of the oral cavity, we determined the proportion and identity of amylase-binding bacteria (ABB) in dental plaque of humans and various salivary amylase-secreting and non-secreting mammalian species. The numbers of ABB in undisturbed plaque collected over time from tooth surfaces of six human volunteers or from 14 other mammalian species were determined by means of a replicating assay. The mean proportion of ABB cultured aerobically from human teeth at 2 h was 10.5% (SD 10), at 8 h 7.9% (8), at 24 h 13% (11), and at 48 h 12% (9). The mean proportion of anaerobically cultured ABB found at 2 h was 3% (SD 4), at 8 h 5% (5), at 24 h 12% (9), and at 48 h 16% (12). Amylase-binding bacteria cultured from these samples resembled Streptococcus mitis, Streptococcus gordonii, Streptococcus salivarius, Streptococcus crista, or unidentified streptococci. In addition, only animals exhibiting salivary amylase activity in their saliva harbored ABB (ranging from 2 to 31% of the total flora), with the exception of the pig, where no ABB were found to colonize, despite considerable amylase activity in saliva. Only strains resembling S. mitis and S. salivarius and unspeciated strains were isolated from these mammals. These results suggest that amylase-binding streptococci are the predominant ABB in human plaque, and their numbers generally increase as plaque develops. Since ABB colonized only the oral cavities of hosts demonstrating salivary amylase activity, the ability to bind amylase may play an important role in oral colonization by these bacteria.