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Mazzini G, Le Foll C, Boyle CN, Garelja ML, Zhyvoloup A, Miller MET, Hay DL, Raleigh DP, Lutz TA. The processing intermediate of human amylin, pro-amylin(1-48), has in vivo and in vitro bioactivity. Biophys Chem 2024; 308:107201. [PMID: 38452520 PMCID: PMC11223094 DOI: 10.1016/j.bpc.2024.107201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 01/31/2024] [Accepted: 02/13/2024] [Indexed: 03/09/2024]
Abstract
Amylin is released by pancreatic beta-cells in response to a meal and its major soluble mature form (37 amino acid-peptide) produces its biological effects by activating amylin receptors. Amylin is derived from larger propeptides that are processed within the synthesizing beta-cell. There are suggestions that a partially processed form, pro-amylin(1-48) is also secreted. We tested the hypothesis that pro-amylin(1-48) has biological activity and that human pro-amylin(1-48) may also form toxic pre-amyloid species. Amyloid formation, the ability to cross-seed and in vitro toxicity were similar between human pro-amylin(1-48) and amylin. Human pro-amylin(1-48) was active at amylin-responsive receptors, though its potency was reduced at rat, but not human amylin receptors. Pro-amylin(1-48) was able to promote anorexia by activating neurons of the area postrema, amylin's primary site of action, indicating that amylin can tolerate significant additions at the N-terminus without losing bioactivity. Our studies help to shed light on the possible roles of pro-amylin(1-48) which may be relevant for the development of future amylin-based drugs.
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Affiliation(s)
- Giulia Mazzini
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Christelle Le Foll
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Christina N Boyle
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Michael L Garelja
- Department of Pharmacology and Toxicology, University of Otago, New Zealand
| | - Alexander Zhyvoloup
- Research Department of Structural and Molecular Biology, University College London, UK
| | | | - Debbie L Hay
- Department of Pharmacology and Toxicology, University of Otago, New Zealand.
| | - Daniel P Raleigh
- Research Department of Structural and Molecular Biology, University College London, UK; Department of Chemistry, Stony Brook University, USA; Laufer Center for Quantitative Biology Stony Brook University, USA.
| | - Thomas A Lutz
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
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Lutz TA. Mammalian models of diabetes mellitus, with a focus on type 2 diabetes mellitus. Nat Rev Endocrinol 2023; 19:350-360. [PMID: 36941447 DOI: 10.1038/s41574-023-00818-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/21/2023] [Indexed: 03/23/2023]
Abstract
Although no single animal model replicates all aspects of diabetes mellitus in humans, animal models are essential for the study of energy balance and metabolism control as well as to investigate the reasons for their imbalance that could eventually lead to overt metabolic diseases such as type 2 diabetes mellitus. The most frequently used animal models in diabetes mellitus research are small rodents that harbour spontaneous genetic mutations or that can be manipulated genetically or by other means to influence their nutrient metabolism and nutrient handling. Non-rodent species, including pigs, cats and dogs, are also useful models in diabetes mellitus research. This Review will outline the advantages and disadvantages of selected animal models of diabetes mellitus to build a basis for their most appropriate use in biomedical research.
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Affiliation(s)
- Thomas A Lutz
- Institute of Veterinary Physiology, Vetsuisse Faculty University of Zurich, Zurich, Switzerland.
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3
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Zini E, Lunardi F, Zanetti R, Heller RS, Coppola LM, Ferro S, Guscetti F, Osto M, Lutz TA, Reusch CE, Cavicchioli L. Endocrine Pancreas in Cats With Diabetes Mellitus. Vet Pathol 2015; 53:136-44. [DOI: 10.1177/0300985815591078] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Pancreatic amyloidosis and loss of α and β cells have been shown to occur in cats with diabetes mellitus, although the number of studies currently available is very limited. Furthermore, it is not known whether pancreatic islet inflammation is a common feature. The aims of the present study were to characterize islet lesions and to investigate whether diabetic cats have inflammation of the pancreatic islets. Samples of pancreas were collected postmortem from 37 diabetic and 20 control cats matched for age, sex, breed, and body weight. Histologic sections were stained with hematoxylin and eosin and Congo red; double labeled for insulin/CD3, insulin/CD20, insulin/myeloperoxidase, insulin/proliferating cell nuclear antigen, and glucagon/Ki67; and single labeled for amylin and Iba1. Mean insulin-positive cross-sectional area was approximately 65% lower in diabetic than control cats ( P = .009), while that of amylin and glucagon was similar. Surprisingly, amyloid deposition was similar between groups ( P = .408). Proliferation of insulin- and glucagon-positive cells and the number of neutrophils, macrophages, and T (CD3) and B (CD20) lymphocytes in the islets did not differ. The presence of T and B lymphocytes combined tended to be more frequent in diabetic cats ( n = 8 of 37; 21.6%) than control cats ( n = 1 of 20; 5.0%). The results confirm previous observations that loss of β cells but not α cells occurs in diabetic cats. Islet amyloidosis was present in diabetic cats but was not greater than in controls. A subset of diabetic cats had lymphocytic infiltration of the islets, which might be associated with β-cell loss.
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Affiliation(s)
- E. Zini
- Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
- Department of Animal Medicine, Production, and Health, University of Padova, Legnaro, Italy
- Istituto Veterinario di Novara, Granozzo con Monticello, Italy
| | - F. Lunardi
- Department of Cardiac, Thoracic and Vascular Sciences, University of Padova, Padova, Italy
| | - R. Zanetti
- Department of Comparative Biomedicine and Food Sciences, University of Padova, Legnaro, Italy
| | - R. S. Heller
- Department of Histology and Imaging, Novo Nordisk A/S, Måløv, Denmark
| | - L. M. Coppola
- Department of Animal Medicine, Production, and Health, University of Padova, Legnaro, Italy
| | - S. Ferro
- Department of Comparative Biomedicine and Food Sciences, University of Padova, Legnaro, Italy
| | - F. Guscetti
- Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - M. Osto
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - T. A. Lutz
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
- Institute of Laboratory Animal Science, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
- Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - C. E. Reusch
- Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - L. Cavicchioli
- Department of Comparative Biomedicine and Food Sciences, University of Padova, Legnaro, Italy
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Osto M, Lutz TA. Translational value of animal models of obesity-Focus on dogs and cats. Eur J Pharmacol 2015; 759:240-52. [PMID: 25814247 DOI: 10.1016/j.ejphar.2015.03.036] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 01/15/2015] [Accepted: 03/12/2015] [Indexed: 12/11/2022]
Abstract
A prolonged imbalance between a relative increase in energy intake over a decrease in energy expenditure results in the development of obesity; extended periods of a positive energy balance eventually lead to the accumulation of abnormally high amounts of fat in adipose tissue but also in other organs. Obesity is considered a clinical state of impaired general heath in which the excessive increase in adipose tissue mass may be associated with metabolic disorders such as type 2 diabetes mellitus, hyperlipidemia, hypertension and cardiovascular diseases. This review discusses briefly the use of animal models for the study of obesity and its comorbidities. Generally, most studies are performed with rodents, such as diet induced obesity and genetic models. Here, we focus specifically on two different species, namely dogs and cats. Obese dogs and cats show many features of human obesity. Interestingly, however, dogs and cats differ from each other in certain aspects because even though obese dogs may become insulin resistant, this does not result in the development of diabetes mellitus. In fact, diabetes in dogs is typically not associated with obesity because dogs present a type 1 diabetes-like syndrome. On the other hand, obese cats often develop diabetes mellitus which shares many features with human type 2 diabetes; feline and human diabetes are similar in respect to their pathophysiology, underlying risk factors and treatment strategies. Our review discusses genetic and endocrine factors in obesity, discusses obesity induced changes in lipid metabolism and includes some recent findings on the role of gut microbiota in obesity. Compared to research in rodent models, the array of available techniques and tools is unfortunately still rather limited in dogs and cats. Hence, even though physiological and pathophysiological phenomena are well described in dogs and cats, the underlying mechanisms are often not known and studies investigating causality specifically are scarce.
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Affiliation(s)
- Melania Osto
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, CH 8057 Zurich, Switzerland
| | - Thomas A Lutz
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, CH 8057 Zurich, Switzerland; Institute of Laboratory Animal Science, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 190, CH 8057 Zurich, Switzerland; Zurich Center for Integrative Human Physiology, University of Zurich, Winterthurerstrasse 190, CH 8057 Zurich, Switzerland.
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5
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Herndon AM, Breshears MA, McFarlane D. Oxidative modification, inflammation and amyloid in the normal and diabetic cat pancreas. J Comp Pathol 2014; 151:352-62. [PMID: 25124331 DOI: 10.1016/j.jcpa.2014.06.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Revised: 06/18/2014] [Accepted: 06/25/2014] [Indexed: 01/15/2023]
Abstract
The pathogenesis of β-cell dysfunction leading to pancreatic β-cell failure seen in type 2 diabetes mellitus is incompletely understood. Pancreatic tissues were collected from nine control cats and nine diabetic cats and labelled immunohistochemically to examine expression of interleukin (IL)-1β, insulin, islet amyloid polypeptide (IAPP) and 4-hydroxynonenal (4-HNE). Thioflavin-S was used to stain for amyloid. All control cats showed positive labelling for IL-1β and 4-HNE. Diabetic cats showed varying degrees of inflammation and oxidative modification, owing in large part to the very small amount of islet structure remaining in the typical diabetic cat pancreas. Amyloid deposition was identified in 8/9 diabetic cats and 1/9 control cats. In order to validate these findings, paired biopsy samples taken from an additional group of cats enrolled in a study of obesity and hyperglycaemia (sampling at baseline and after 8-16 weeks of obesity and hyperglycaemia) were labelled for IL-1β and 4-HNE. A similar pattern of labelling was identified in the baseline samples to that seen in control cats. A significant increase in IL-1β and 4-HNE expression was seen after a period of hyperglycaemia and obesity. Taken together, these findings suggest that while present in normal cats, markers of inflammation and oxidative modification increase very early during the development of disease. Future studies focusing on these earlier time points are needed to understand the factors that function in protection of the islet β cell and the development of islet pathology in type 2 diabetes mellitus in the cat.
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Affiliation(s)
- A M Herndon
- Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
| | - M A Breshears
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | - D McFarlane
- Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA
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Rand JS, Fleeman LM, Farrow HA, Appleton DJ, Lederer R. Canine and Feline Diabetes Mellitus: Nature or Nurture? J Nutr 2004; 134:2072S-2080S. [PMID: 15284406 DOI: 10.1093/jn/134.8.2072s] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
There is evidence for the role of genetic and environmental factors in feline and canine diabetes. Type 2 diabetes is the most common form of diabetes in cats. Evidence for genetic factors in feline diabetes includes the overrepresentation of Burmese cats with diabetes. Environmental risk factors in domestic or Burmese cats include advancing age, obesity, male gender, neutering, drug treatment, physical inactivity, and indoor confinement. High-carbohydrate diets increase blood glucose and insulin levels and may predispose cats to obesity and diabetes. Low-carbohydrate, high-protein diets may help prevent diabetes in cats at risk such as obese cats or lean cats with underlying low insulin sensitivity. Evidence exists for a genetic basis and altered immune response in the pathogenesis of canine diabetes. Seasonal effects on the incidence of diagnosis indicate that there are environmental influences on disease progression. At least 50% of diabetic dogs have type 1 diabetes based on present evidence of immune destruction of beta-cells. Epidemiological factors closely match those of the latent autoimmune diabetes of adults form of human type 1 diabetes. Extensive pancreatic damage, likely from chronic pancreatitis, causes approximately 28% of canine diabetes cases. Environmental factors such as feeding of high-fat diets are potentially associated with pancreatitis and likely play a role in the development of pancreatitis in diabetic dogs. There are no published data showing that overt type 2 diabetes occurs in dogs or that obesity is a risk factor for canine diabetes. Diabetes diagnosed in a bitch during either pregnancy or diestrus is comparable to human gestational diabetes.
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Affiliation(s)
- Jacquie S Rand
- Centre for Companion Animal Health, School of Veterinary Science, The University of Queensland, Brisbane 4072, Australia.
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Mazzaferro EM, Greco DS, Turner AS, Fettman MJ. Treatment of feline diabetes mellitus using an alpha-glucosidase inhibitor and a low-carbohydrate diet. J Feline Med Surg 2003; 5:183-9. [PMID: 12765629 DOI: 10.1016/s1098-612x(03)00006-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The purpose of this study was to determine the effect of an alpha-glucosidase inhibitor (acarbose), combined with a low-carbohydrate diet on the treatment of naturally occurring diabetes mellitus in cats. Eighteen client-owned cats with naturally occurring diabetes mellitus were entered into the study. Dual-energy X-ray absorptiometry (DEXA) was performed prior to and 4 months after feeding the diet to determine total body composition, including lean body mass (LBM) and percent body fat. Each cat was fed a commercially available low-carbohydrate canned feline diet and received 12.5mg/cat acarbose orally every 12h with meals. All cats received subcutaneous insulin therapy except one cat in the study group that received glipizide (5mg BID PO). Monthly serum glucose and fructosamine concentrations were obtained, and were used to adjust insulin doses based on individual cat's requirements. Patients were later classified as responders (insulin was discontinued, n=11) and non-responders (continued to require insulin or glipizide, n=7). Responders were initially obese (>28% body fat) and non-responders had significantly less body fat than responders (<28% body fat). Serum fructosamine and glucose concentrations decreased significantly in both responder and non-responder groups over the course of 4 months of therapy. Better results were observed in responder cats, for which exogenous insulin therapy was discontinued, glycemic parameters improved, and body fat decreased. In non-responders, median insulin requirements decreased and glycemic parameters improved significantly, despite continued insulin dependence. The use of a low-carbohydrate diet with acarbose was an effective means of decreasing exogenous insulin dependence and improving glycemic control in a series of client-owned cats with naturally occurring diabetes mellitus.
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Affiliation(s)
- E M Mazzaferro
- Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
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8
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Abstract
Diabetes mellitus is a common disease in cats and dogs. Its incidence is increasing, possibly due to an increase in obesity in both species. Different types of diabetes have been identified in pet animals. The classification of diabetic dogs and cats is modeled after the human classification but especially in the diabetic dogs, many aspects are different. The diabetic cat, however, resembles type 2 diabetic human patients more closely. The clinical presentation, pathophysiology, and histologic findings are described for both dog and cat and possible etiological mechanisms are discussed.
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Affiliation(s)
- M Hoenig
- Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.
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9
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Cooper GJS. Amylin and Related Proteins: Physiology and Pathophysiology. Compr Physiol 2001. [DOI: 10.1002/cphy.cp070210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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10
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Abstract
Up to one quarter of diabetic cats can be well controlled with oral hypoglycemic drugs, although at least 75% require insulin therapy. Most available insulins provide good clinical control but only moderate glycemic control. Because mild to moderate hyperglycemia is well tolerated by cats receiving insulin but hypoglycemia can be life threatening, conservative insulin dosing is recommended. Clinical signs and water intake indicate whether a dose adjustment is required, but serial blood glucose measurements are usually needed to determine the direction of the adjustment. Starting doses of 0.3 to 0.5 IU/kg administered twice daily (rounded down to the nearest whole unit) are usually safe. Dose adjustments should not exceed 1 IU per cat every 2 to 4 weeks unless clinical hypoglycemia has occurred. Cats with clinical hypoglycemia need to be reassessed to see if they are in remission. If not, a 50% to 75% reduction in dose is advised. Approximately 30% of cats go into diabetic remission 1 to 4 months after an adequate treatment protocol is instituted.
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Affiliation(s)
- J S Rand
- Companion Animal Centre for Diabetes and Obesity, Companion Animal Sciences, School of Veterinary Science, University of Queensland, Queensland, Australia.
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11
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Abstract
Type-1 diabetes, resulting from immune-mediated destruction of beta cells, appears to be rare in cats. Type-2 diabetes, characterised by inadequate insulin secretion and impaired insulin action, is the most common form of diabetes in cats. Other specific forms of diabetes constitute a substantial minority of cases. The most common is pancreatic destruction from pancreatic adenocarcinoma. Less frequent causes are insulin resistance from other endocrinopathies including acromegaly. Diabetes in cats is characterised by variable loss of insulin secretory capacity and insulin resistance. Glucose toxicity, islet amyloid-deposition, and pancreatitis contribute to further loss of beta cells and failure of insulin secretion. A significant number of cats undergo remission of their diabetes, usually 1-3 months after good glycaemic control is instituted. Obesity, old age, and Burmese breed are recognised risk factors for the development of diabetes in cats.
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Affiliation(s)
- J Rand
- Companion Animal Sciences, School of Veterinary Science and Animal Production, The University of Queensland, Australia 4072
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12
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Nelson RW, Griffey SM, Feldman EC, Ford SL. Transient Clinical Diabetes Mellitus in Cats: 10 Cases (1989-1991). J Vet Intern Med 1999. [DOI: 10.1111/j.1939-1676.1999.tb02161.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Goossens MM, Nelson RW, Feldman EC, Griffey SM. Response to insulin treatment and survival in 104 cats with diabetes mellitus (1985-1995). J Vet Intern Med 1998; 12:1-6. [PMID: 9503353 DOI: 10.1111/j.1939-1676.1998.tb00489.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Medical records of 104 cats with diabetes mellitus were reviewed. Information from 54 cats that had multiple blood glucose concentrations evaluated at least 5 times over a minimum of 3 months, beginning at the time insulin treatment was initiated, was used to evaluate the efficacy of insulin in treating diabetes mellitus. Fourteen of 54 cats were treated with protamine zinc insulin (PZI), 26 with ultralente insulin, and 14 with lente insulin. Six, 29, and 19 cats had good, mediocre, and poor glycemic control, respectively, based on mean blood glucose concentrations, whereas 31, 21, and 2 owners thought clinical response was good, mediocre, and poor, respectively. No significant difference was found in glycemic control among cats treated with PZI, ultralente, or lente insulin. Glycemic control was significantly (P < .05) better in 33 cats without than in 21 cats with concurrent disease. All 104 cats were used to calculate survival data. Fifty-one of 104 cats were alive at the time of the study. Mean (+/- standard deviation [SD]) and median survival times were 24 (+/- 16) and 20 months, respectively, in the 51 cats still alive at the end of the evaluation, and 25 (+/- 4) and 17 months, respectively, in the 53 cats that had died during the period of evaluation. Pancreatic abnormalities identified in 37 cats that underwent necropsy included chronic pancreatitis (n = 17), acute to subacute pancreatitis (n = 2), exocrine pancreatic adenocarcinoma (n = 7) and adenoma (n = 1), islet cell atrophy and vacuolar degeneration (n = 27), and islet amyloidosis (n = 8). No association was found between glycemic control and islet amyloidosis or exocrine pancreatic neoplasia, or between survival time and chronic pancreatitis, islet amyloidosis, or exocrine pancreatic neoplasia. In conclusion, diabetic cats evaluated in this study showed a variable response to exogenously administered insulin, ranging from excellent to poor. By maintaining mean blood glucose concentrations under 300 mg/dL, clinical signs were improved, and owners were satisfied with insulin treatment. Concurrent potentially insulin-antagonistic diseases were common and deleteriously affected glycemic control and survival time.
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Affiliation(s)
- M M Goossens
- Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis 95616, USA
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Abstract
OBJECTIVE To determine if Burmese cats in Queensland have an increased risk of diabetes mellitus. DESIGN A retrospective study of diabetic and nondiabetic cats that had blood submitted to a veterinary clinical laboratory over a 22 month study period. SAMPLE POPULATION 4402 cats PROCEDURE Cats were considered diabetic if blood glucose concentration was > 11 mmol/L and fructosamine was > 406 mumol/L or hydroxybutyrate was > 1 mmol/L. Cats were grouped into Burmese and non-Burmese. Adjusted odds ratios of diabetes were calculated for breed, gender and age group amongst cats with blood glucose > 11 mmol/L. RESULTS Burmese cats comprised 20% of 45 diabetic cats of known breed, which was higher (P < 0.001) than among the normoglycemic reference population of 2203 cats (7% Burmese). There were more females among the diabetic Burmese (62%), but this did not differ (P > 0.05) from the Burmese reference population (45% females). In contrast, males seemed to predominate among diabetic non-Burmese (63%), although this also did not differ (P > 0.05) from the reference population (55%) of from diabetic Burmese (38% males). The majority (90%) of diabetic cats were older than 6 years, irrespective of breed (median age 12 years, interquartile range 10 to 13 years). This was higher (chi(2) = 8.13, P < 0.005) than among the normoglycaemic reference population, where 69% were older than 6 years. CONCLUSIONS Burmese cats were significantly over represented among cats with diabetes mellitus. Irrespective of breed, the risk of diabetes in the study population increased with age.
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Affiliation(s)
- J S Rand
- School of Veterinary Science, University of Queensland, South Australia
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15
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Lutz TA, Rand JS. Detection of amyloid deposition in various regions of the feline pancreas by different staining techniques. J Comp Pathol 1997; 116:157-70. [PMID: 9131431 DOI: 10.1016/s0021-9975(97)80073-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Deposition of islet amyloid is a common finding in the pancreas of diabetic cats and it may contribute to the deterioration of glucose tolerance. Three techniques for detecting pancreatic amyloid deposition were compared in cats not known to be diabetic. Congo red (CR) staining was used for histological sections (35 cats) and tissue smear preparations (crush and smear [CS] technique; 35 cats, and an immunohistochemical method (18 cats) was used for the detection of amyloid derived from amylin. Six diabetic cats were used as positive controls for the immunohistochemical method. The amount of pancreatic amyloid demonstrated immunohistochemically was significantly correlated with that shown by CR staining in histological sections but not in CS preparations, which were less satisfactory. However, the amount of amyloid determined immunohistochemically was slightly but significantly higher than that seen in CR-stained sections. There was no difference in the amount of amyloid between the left limb middle segment and right limb of the pancreas. Amylin labelling was seen in about 70 to 80% of islet cells, mainly those located in the islet periphery and the labelling was most intense in the cell periphery.
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Affiliation(s)
- T A Lutz
- Companion Animal Medicine and Surgery, School of Veterinary Science, University of Queensland, St. Lucia, Australia
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Abstract
Cats are one of the few species that develop a form of diabetes mellitus that is clinically and histologically analogous to human type 2 diabetes mellitus. Figure 9 summarizes the etiologic factors thought to be involved in the development of feline and human type 2 diabetes. The main metabolic characteristics of type 2 diabetes mellitus are impaired insulin secretion and resistance to the action of insulin in its target tissues. Impaired beta cell function occurs before histologic changes become evident. The characteristic histologic finding in cats with type 2 diabetes is deposition of amyloid in pancreatic islets. Amyloid deposition occurs before the onset of clinical signs, but does not seem to be the primary defect. Pancreatic amyloid is derived form the recently discovered pancreatic hormone amylin. Amylin is synthesized in pancreatic beta cells, and is co-stored and co-secreted with insulin. Amylin has been postulated to be involved in the pathogenesis of feline diabetes mellitus both through its metabolic effects, which include inhibition of insulin secretion and induction of insulin resistance, and via progressive amyloid deposition and beta cell degeneration. Increased amylin concentration has been documented intracellularly in cats with impaired glucose tolerance and in the plasma of diabetic cats, and supports the hypothesis that amylin is involved in the pathogenesis of type 2 diabetes. Obesity is a common finding in diabetic felines and is a contributing factor to the insulin resistance present in type 2 diabetes. Clinical signs of diabetes develop once total insulin secretion decreases to 20% to 25% of normal levels. Many diabetic cats have been treated successfully with oral hypoglycemics, but 50% to 70% of diabetic cats are insulin dependent. Based on histologic evidence, this is the result of extensive amyloid deposition and subsequent beta cell degeneration, rather than autoimmune destruction of pancreatic beta cells associated with type 1 diabetes. Alternative ways of treating type 2 diabetes currently are being investigated. Amylin antagonists recently have been proposed as a novel treatment to reverse the deleterious effects of excessive amylin concentrations. The gastrointestinal hormone glucagon-like peptide-1 may also prove useful in treating diabetic cats, because of its stimulatory effect on insulin secretion and synthesis, and the absence of significant hypoglycemic effect.
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Affiliation(s)
- T A Lutz
- Institute of Veterinary Physiology, University of Zůrich, Switzerland
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