Pancreatic lipomatosis is a structural marker in nondiabetic children with mutations in carboxyl-ester lipase

Severe pancreatic dysfunction but compensated nutritional status in monogenic pancreatic disease caused by carboxyl-ester lipase mutations

OBJECTIVES

The impact of pancreatic dysfunction in several diseases of the pancreas, including chronic pancreatitis and cystic fibrosis, is obscured by concomitant extra-pancreatic disease. Carboxyl-ester lipase-maturity-onset diabetes in the young (CEL-MODY) is a monogenic, highly penetrant and progressive pancreatic disease with no known primary extrapancreatic manifestations. It is characterized by low fecal elastase, steatorrhea, and development of diabetes mellitus. We sought to determine the nature of the exocrine dysfunction in CEL-MODY and relate the findings to clinical parameters of malnutrition.

METHODS

We examined CEL-MODY patients and control subjects by rapid, endoscopic secretin test and dynamic magnetic resonance imaging of the pancreas. The findings were related to the subjects' clinical status.

RESULTS

The CEL-MODY patients displayed severely reduced acinar function and moderately reduced ductal function of the pancreas compared with control subjects. Surprisingly, CEL-MODY patients did not have clinical or biochemical signs of malnutrition, except for subnormal levels of vitamin E. Vitamin E levels seemed to be directly related to pancreatic acinar function.

CONCLUSIONS

Pancreatic exocrine dysfunction in CEL-MODY is associated with severely reduced acinar and moderately reduced ductal dysfunction. Despite severely reduced exocrine pancreatic function, CEL-MODY patients revealed only minor signs of malnutrition.

Exocrine pancreatic function in hepatocyte nuclear factor 1β-maturity-onset diabetes of the young (HNF1B-MODY) is only moderately reduced: compensatory hypersecretion from a hypoplastic pancreas

OBJECTIVES

To examine the exocrine pancreatic function in carriers of the hepatocyte nuclear factor 1β gene (HNF1B) mutation by direct testing.

METHODS

Patients with HNF1B mutations and control subjects were assessed using rapid endoscopic secretin tests and secretin-stimulated magnetic resonance imaging. Seven patients and 25 controls underwent endoscopy, while eight patients and 20 controls had magnetic resonance imaging. Ductal function was assessed according to peak bicarbonate concentrations and acinar function was assessed according to peak digestive enzyme activities in secretin-stimulated duodenal juice. The association of pancreatic exocrine function and diabetes status with pancreatic gland volume was examined.

RESULTS

The mean increase in secretin-stimulated duodenal fluid was smaller in patients than controls (4.0 vs 6.4 ml/min; P = 0.003). We found lower ductal function in patients than controls (median peak bicarbonate concentration: 73 vs 116 mEq/L; P < 0.001) and lower acinar function (median peak lipase activity: 6.4 vs 33.5 kU/ml; P = 0.01; median peak elastase activity: 0.056 vs 0.130 U/ml; P = 0.01). Pancreatic fluid volume outputs correlated significantly with pancreatic gland volumes (r² = 0.71, P = 0.008) in patients. The total fluid output to pancreatic gland volume ratios were higher in patients than controls (4.5 vs 1.3 ml/cm³; P = 0.03), suggesting compensatory hypersecretion in the remaining gland.

CONCLUSION

Carriers of the HNF1B mutation have lower exocrine pancreatic function involving both ductal and acinar cells. Compensatory hypersecretion suggests that the small pancreas of HNF1B mutation carriers is attributable to hypoplasia, not atrophy.

Absence of diabetes and pancreatic exocrine dysfunction in a transgenic model of carboxyl-ester lipase-MODY (maturity-onset diabetes of the young)

Background

CEL-MODY is a monogenic form of diabetes with exocrine pancreatic insufficiency caused by mutations in CARBOXYL-ESTER LIPASE (CEL). The pathogenic processes underlying CEL-MODY are poorly understood, and the global knockout mouse model of the CEL gene (CELKO) did not recapitulate the disease. We therefore aimed to create and phenotype a mouse model specifically over-expressing mutated CEL in the pancreas.

Methods

We established a monotransgenic floxed (flanking LOX sequences) mouse line carrying the human CEL mutation c.1686delT and crossed it with an elastase-Cre mouse to derive a bitransgenic mouse line with pancreas-specific over-expression of CEL carrying this disease-associated mutation (TgCEL). Following confirmation of murine pancreatic expression of the human transgene by real-time quantitative PCR, we phenotyped the mouse model fed a normal chow and compared it with mice fed a 60% high fat diet (HFD) as well as the effects of short-term and long-term cerulein exposure.

Results

Pancreatic exocrine function was normal in TgCEL mice on normal chow as assessed by serum lipid and lipid-soluble vitamin levels, fecal elastase and fecal fat absorption, and the normoglycemic mice exhibited normal pancreatic morphology. On 60% HFD, the mice gained weight to the same extent as controls, had normal pancreatic exocrine function and comparable glucose tolerance even after resuming normal diet and follow up up to 22 months of age. The cerulein-exposed TgCEL mice gained weight and remained glucose tolerant, and there were no detectable mutation-specific differences in serum amylase, islet hormones or the extent of pancreatic tissue inflammation.

Conclusions

In this murine model of human CEL-MODY diabetes, we did not detect mutation-specific endocrine or exocrine pancreatic phenotypes, in response to altered diets or exposure to cerulein.

The role of pancreatic imaging in monogenic diabetes mellitus

In neonatal diabetes mellitus resulting from mutations in EIF2AK3, PTF1A, HNF1B, PDX1 or RFX6, pancreatic aplasia or hypoplasia is typical. In maturity-onset diabetes mellitus of the young (MODY), mutations in HNF1B result in aplasia of pancreatic body and tail, and mutations in CEL lead to lipomatosis. The pancreas is not readily accessible for histopathological investigations and pancreatic imaging might, therefore, prove important for diagnosis, treatment, and research into these β-cell diseases. Advanced imaging techniques can identify the pancreatic features that are characteristic of inherited diabetes subtypes, including alterations in organ size (diffuse atrophy and complete or partial pancreatic agenesis), lipomatosis and calcifications. Consequently, in patients with suspected monogenic diabetes mellitus, the results of pancreatic imaging could help guide the molecular and genetic investigation. Imaging findings also highlight the critical roles of specific genes in normal pancreatic development and differentiation and provide new insight into alterations in pancreatic structure that are relevant for β-cell disease.

Diabetes and pancreatic exocrine dysfunction due to mutations in the carboxyl ester lipase gene-maturity onset diabetes of the young (CEL-MODY): a protein misfolding disease

CEL-maturity onset diabetes of the young (MODY), diabetes with pancreatic lipomatosis and exocrine dysfunction, is due to dominant frameshift mutations in the acinar cell carboxyl ester lipase gene (CEL). As Cel knock-out mice do not express the phenotype and the mutant protein has an altered and intrinsically disordered tandem repeat domain, we hypothesized that the disease mechanism might involve a negative effect of the mutant protein. In silico analysis showed that the pI of the tandem repeat was markedly increased from pH 3.3 in wild-type (WT) to 11.8 in mutant (MUT) human CEL. By stably overexpressing CEL-WT and CEL-MUT in HEK293 cells, we found similar glycosylation, ubiquitination, constitutive secretion, and quality control of the two proteins. The CEL-MUT protein demonstrated, however, a high propensity to form aggregates found intracellularly and extracellularly. Different physicochemical properties of the intrinsically disordered tandem repeat domains of WT and MUT proteins may contribute to different short and long range interactions with the globular core domain and other macromolecules, including cell membranes. Thus, we propose that CEL-MODY is a protein misfolding disease caused by a negative gain-of-function effect of the mutant proteins in pancreatic tissues.

Role of molecular genetics in transforming diagnosis of diabetes mellitus

Most common diseases also run in families as rare, monogenic forms. Diabetes is no exception. Mutations in approximately 20 different genes are now known to cause monogenic diabetes, a disease group that can be subclassified into maturity-onset diabetes of the young, neonatal diabetes and mitochondrial diabetes. In some families, additional features, such as urogenital malformations, exocrine pancreatic dysfunction and neurological abnormalities, are present and may aid the diagnostic classification. The finding of a mutation in monogenic diabetes may have implications for the prediction of prognosis and choice of treatment. Mutations in the GCK gene cause a mild form of diabetes, which seldom needs insulin and has a low risk for complications. By contrast, HNF1A mutations lead to a diabetes form that in severity, treatment and complication risk resembles Type 1 diabetes, although these patients may experience a good effect of sulfonylurea treatment. The majority of neonatal diabetes cases are caused by mutations in the K(ATP) channel genes ABCC8 and KCNJ11, and sulfonylurea therapy is then usually superior to insulin. Diseases with a considerable genetic component may now be explored by genome-wide approaches using next-generation DNA sequencing technology. We expect that within a few years important breakthroughs will be made in mapping cases of diabetes with a suspected, but still unsolved monogenic basis.

The clinical significance of pancreatic steatosis

More research is now focused on pancreatic steatosis. Multiple definitions, clinical associations and synonyms for pancreatic steatosis are described in the literature and can be confusing. The integration and comparison of several studies concerning this topic is therefore challenging. In the past, pancreatic steatosis was considered an innocuous condition, a bystander of many underlying diseases (such as congenital syndromes, hemochromatosis and viral infection). However, evidence that pancreatic steatosis (strongly associated with obesity and the metabolic syndrome) has a role in type 2 diabetes mellitus, pancreatic exocrine dysfunction, acute pancreatitis, pancreatic cancer and the formation of pancreatic fistula after pancreatic surgery is emerging. This Review focuses on the different etiological factors and the clinical consequences of pancreatic steatosis.

Liver and pancreatic fat content and metabolism in healthy monozygotic twins with discordant physical activity

BACKGROUND & AIMS

Ectopic fat in muscle and liver is linked to obesity and type 2 diabetes. Recently, pancreatic lipid accumulation has also been associated with β-cell dysfunction and reduced insulin production, leading to the development of type 2 diabetes. Physical exercise training has been shown to attenuate β-cell dysfunction in patients, but little is known about its effects on pancreatic and hepatic fat accumulation. In this study, we validated in-vivo proton magnetic resonance spectroscopy ((1)H MRS) in pancreatic fat measurement with biochemical measurements in a pig model. Thereafter, the effects of increased physical activity on the amounts of pancreatic and liver fat were studied in eight monozygotic twin pairs who have discordant physical activity and fitness.

METHODS

Pancreatic fat content was studied in 15 pigs using (1)H MRS and/or biochemical analyses. In addition, liver and pancreatic fat were assessed using (1)H MRS in eight monozygotic male twin pairs with 18% mean difference in VO(2max) between the twin brothers.

RESULTS

Twins with higher physical fitness had 23% less liver fat (1.3±1.3% vs. 2.1±2.6%, p=0.022) but no such difference was observed in the pancreatic fat (8.2±9.3% vs. 9.8±8.5%, respectively, p=0.3). Hepatic fat content was inversely associated with VO(2max). A positive association was found between pancreatic and liver fat contents (β=5.18, p=0.012). Pancreatic fat content was also associated with insulin sensitivity indexes and plasma adiponectin and glutamyltransferase concentrations.

CONCLUSIONS

Pancreatic fat content is associated with insulin resistance and hepatic fat content. An active lifestyle seems to beneficially influence hepatic fat metabolism.

Pancreatic function in carboxyl-ester lipase knockout mice

BACKGROUND/AIMS

CEL-MODY is a monogenic form of diabetes and exocrine pancreatic insufficiency due to mutations in the carboxyl-ester lipase (CEL) gene. We aimed to investigate endocrine and exocrine pancreatic function in CEL knockout mice (CELKO).

METHODS

A knockout mouse model with global targeted deletion of CEL was investigated physiologically and histopathologically, and compared to littermate control CEL+/+ mice at 7 and 12 months on normal chow and high-fat diets (HFD), i.e. 42 and 60% fat by calories.

RESULTS

CELKO+/+ and -/- mice showed normal growth and development and normal glucose metabolism on a chow diet. Female CEL-/- mice on 60% HFD, on the other hand, had increased random blood glucose compared to littermate controls (p = 0.02), and this was accompanied by a reduction in glucose tolerance that did not reach statistical significance. In these mice there was also islet hyperplasia, however, α- and β-islet cells appeared morphologically normal and pancreatic exocrine function was also normal.

CONCLUSION

Although we observed mild glucose intolerance in female mice with whole-body knockout of CEL, the full phenotype of human CEL-MODY was not reproduced, suggesting that the pathogenic mechanisms involved are more complex than a simple loss of CEL function. and IAP.

Measurement of pancreatic fat by magnetic resonance imaging: predicting the occurrence of pancreatic fistula after pancreatoduodenectomy

OBJECTIVE

The purpose of this study was to determine whether patients who develop a pancreatic fistula after pancreatoduodenectomy are more likely to have higher pancreatic fat levels than matched controls and if so, to investigate whether preoperative dual gradient-echo magnetic resonance (MR) imaging can be used to measure pancreatic fat and predict the development of postoperative pancreatic fistula.

SUMMARY BACKGROUND DATA

Pancreatic fistula is a major complication and its most frequently reported risk factors tend to be anatomic features of the pancreatic remnant, such as a soft pancreatic texture.

METHODS

Between January 2007 and September 2007, a total of 96 cases of pancreatoduodenectomy were performed at Seoul National University Hospital. Of total, 20 patients (20.8%) who developed a pancreatic fistula were carefully matched for multiple parameters including age, gender, pancreatic pathology, surgeon, and type of operation with 20 control patients who did not develop a pancreatic fistula. In the pancreatic fistula group, 9 patients (45%) had a grade A fistula and 11 (55%) grade B fistula. Degrees of pancreatic fatty infiltration and fibrosis were assessed quantitatively. In-phase and opposed-phase images were obtained by dual-gradient-echo MR imaging. Percentage decreases in pancreatic signal intensity on opposed-phase images relative to those on in-phase images were calculated and defined as relative signal intensity decreases (RSID).

RESULTS

More patients in the pancreatic fistula group had a soft pancreatic texture or a smaller pancreatic duct and total fat and RSID were significantly higher. In soft pancreatic texture group, intralobular, interlobular, and total fat were significantly elevated. Furthermore, pancreatic fat levels were found to be correlated positively with RSID (P=0.013). RSID was correlated with total pancreatic fat and when an RSID criterion more than 7.032 was used, pancreatic fistula could be predicted as 72.7% sensitivity and 75.9% specificity.

CONCLUSION

Our findings suggest that increased pancreatic fat is a risk factor of postoperative pancreatic fistula. Preoperative measurements of pancreatic fat by MRI offer a noninvasive predicting the occurrence of pancreatic fistula.

MRI-determined fat content of human liver, pancreas and kidney

AIM: To assess and correlate the lipid content of various organs in obese subjects and in persons with a normal body weight.

METHODS: Magnetic resonance spectroscopy and a previously validated gradient echo magnetic resonance imaging method with Dixon’s two point technique were used in this study to quantify fat in liver, pancreas as well as kidney.

RESULTS: In 36 volunteers with body mass index (BMI) ranging from 20.0 to 42.9 kg/m², the median fat content of liver, pancreas and kidney was 2.3% (interquartile range: 0.2%-7.8%), 2.7% (1.0%-6.5%) and 0.7% (0.1%-1.4%), respectively. BMI and subcutaneous fat correlated significantly with liver and pancreas fat content. We show for the first time the significant correlation of liver and pancreas fat content in healthy controls (r = 0.43, P < 0.01). These observations are related to body weight as measured by BMI and the amount of subcutaneous fat. Kidney fat content is very low and correlates with none of the other fat depots.

CONCLUSION: Renal lipid accumulation, unlike the coupled accumulations of fat in liver and pancreas, is not observed in obese subjects. Unlike suggestions made in previous studies, renal lipid accumulation appears not to be involved in the pathogenesis of renal disease in humans.

Fat replacement of the malignant pancreatic tissue after neoadjuvant therapy

Pancreatic lipomatosis is characterized as massive lipid infiltration of the pancreatic tissue. Although its etiology is ill defined; obesity, diabetes mellitus, chronic pancreatitis, hereditary pancreatitis, and conditions that cause pancreatic ductal obstruction, for example tumors and stones, are related to its pathogenesis. Recently, with the increased use of computerized tomography and magnetic resonance imaging, it has become possible to observe the fat replacement of the pancreas. Herein, we report a 60-year-old man complaining of abdominal pain and weight loss. Preoperative work-up revealed a locally advanced (Stage III) pancreatic adenocarcinoma. Multimodal treatment was carried out and a 100% complete response was detected after neoadjuvant therapy. The patient underwent a standard pancreaticoduodenectomy, without complications. The tissue pathology revealed lipomatosis of the pancreas. He was disease-free and symptom-free at 1 year follow-up. To our knowledge, this is the first report in the literature of pancreatic head carcinoma with total fat replacement of the pancreas after neoadjuvant chemoradiotherapy.

Metastatic uterine adenocarcinoma and hepatic lipomatosis in a llama (Lama glama)

A 6-year-old, female llama (Lama glama) presented with progressive anorexia and ascites. Postmortem examination revealed an infiltrative uterine adenocarcinoma with widespread metastases. The neoplasm completely replaced and infiltrated the myometrium of the uterine body and cervix and metastasized largely to the serosal surfaces of the peritoneal cavity. Histopathology identified a highly invasive growth of neoplastic cells in solid packets or tubular arrangements and marked fibroplasia. No bovine or llama papillomavirus DNA was detected intralesionally by polymerase chain reaction.

Reduced pancreatic volume in hepatocyte nuclear factor 1A-maturity-onset diabetes of the young

CONTEXT

There are interplays between the endocrine and exocrine pancreas. We recently reported an increased frequency of exocrine dysfunction in HNF1A-maturity-onset diabetes of the young (MODY3) patients, compared with controls. Reduced pancreatic volume is seen in HNF1B-MODY (MODY5) and diabetes types 1 and 2.

OBJECTIVE

The aim of this study was to investigate whether HNF1A mutation carriers have reduced pancreatic volume or abnormal pancreatic structure and whether any changes are associated with exocrine dysfunction.

METHODS

Fifteen HNF1A mutation carriers recruited from the Norwegian MODY Registry, 31 subjects with type 1 diabetes, 10 subjects with type 2 diabetes, and 11 controls underwent computed tomography of the pancreas. We measured pancreatic volume and X-ray attenuation. Pancreatic volume index was defined as pancreatic volume divided by body surface area.

RESULTS

Pancreatic volume index was reduced in subjects with HNF1A-MODY (34.5 ml/m2; P < 0.02) and type 1 diabetes (21.4 ml/m2; P < 0.001) as compared with nondiabetic controls (45.7 ml/m2), and was reduced in subjects with diabetes in combination with fecal elastase deficiency (P = 0.03). Subjects with type 1 diabetes had smaller pancreatic volume index, compared with HNF1A mutation carriers (P < 0.001). Reduced pancreatic volume index was associated with increasing duration of diabetes. Pancreatic X-ray attenuation in HNF1A mutation carriers was not significantly different from that of nondiabetic controls.

CONCLUSIONS

HNF1A mutation carriers have reduced pancreatic volume but less reduced than in patients with type 1 diabetes. Insulinopenia could explain both the pancreatic volume reduction and the associated pancreatic dysfunction.

Neurological features and enzyme therapy in patients with endocrine and exocrine pancreas dysfunction due to CEL mutations

OBJECTIVE

To further define clinical features associated with the syndrome of diabetes and pancreatic exocrine dysfunction due to mutations in the carboxyl-ester lipase (CEL) gene and to assess the effects of pancreatic enzyme substitution therapy.

RESEARCH DESIGN AND METHODS

Nine patients with CEL gene mutation, exocrine deficiency, and diabetes were treated and followed for 30 months.

RESULTS

Treatment improved symptoms in seven of nine patients. Exocrine and endocrine function assessed by fecal elastase and A1C were not affected, although fecal lipid excretion was reduced. Vitamin E was low in all patients but increased with treatment (P < 0.001 at 30 months) and improved in five subjects. A predominantly demyelinating neuropathy was seen in a majority of patients, and carpal tunnel syndrome was common.

CONCLUSIONS

Pancreatic enzyme substitution alleviated symptoms and malabsorption and normalized vitamin E levels. Glycemic control was not significantly affected. The CEL syndrome seems associated with a demyelinating neuropathology.

Lack of pancreatic body and tail in HNF1B mutation carriers

AIMS

Hepatocyte nuclear factor 1B (HNF1B) gene mutation carriers have a systemic disease characterized by congenital malformations in the urogenital tract, diabetes mellitus of maturity-onset diabetes of the young type and dysfunction of the liver and exocrine pancreas. We aimed to investigate pancreatic structure and exocrine function in carriers of HNF1B mutations.

METHODS

We studied five subjects from two families with the previously reported mutation R137_K161del and the novel mutation F148L in HNF1B. All patients underwent computed tomography (CT) and magnetic resonance cholangiopancreatography (MRCP). We measured faecal elastase and serum vitamins D and E.

RESULTS

One of the mutation carriers reported abdominal symptoms. All five subjects had faecal elastase deficiency, three had vitamin D deficiency and two had vitamin E deficiency. Neither CT nor MRCP depicted tissue corresponding to the pancreatic body and tail in the five mutation carriers, indicating agenesis of the dorsal pancreas. The head of the pancreas was slightly atrophic but had normal X-ray attenuation at CT in all patients.

CONCLUSIONS

Agenesis of the pancreatic body and tail and pancreatic exocrine dysfunction are parts of the phenotype in HNF1B mutation carriers. This strengthens the evidence for a critical role of HNF1B in development and differentiation of at least the dorsal pancreas.

Screening of proteins binding to hepatitis B core antigen from human pancreas cDNA library by yeast two-hybrid system

AIM: To screen proteins in human pancreas cDNA library interacting with hepatitis B core antigen (HbcAg) by yeast two-hybrid system.

METHODS: After amplification, purification, and identification, the human pancreas cDNA library plasmid was transformed into yeast Y187. Thereafter, the reconstructed bait plasmid (pGBKT7-HBcAg) was transformed into yeast cells AH109. Then, the transformed AH109 was mated with Y187 that contained the library plasmid. The diploid yeast cells were plated on nutrient deficiency medium SD/-Trp/-Leu/-His/-Ade and SD/-Trp/-Leu/-His/-Ade containing X-α-gal for selecting. The plasmids in diploid yeast cells were extracted and electrotransformed into E.coli DH5α. The plasmids in DH5α were extracted, sequenced and analyzed by bioinformatic methods.

RESULTS: The human pancreas cDNA library was constructed successfully. The reconstructed bait plasmid (pGBKT7-HBcAg) was transformed into yeast cells AH109 successfully. Nine proteins interacting with HBcAg were screened, and their sequences were homologous with human pancreatic lipase (PNLIP), CEL, CTRC, trypsinogen, carboxypeptidase 1 (CPB1), human complete mitochondrial genome, human pancreatic elastinase 2A, human complement lipase (CLPS) and human ribosomal protein (RPL10A).

CONCLUSION: HBcAg protein may be related with the exocrine pancreatic function and metabolism of glucose or lipid. HBV infection probably leads to metabolic abnormality or metabolic diseases through interacting with pancreatic enzymes.

Monogenic diabetes in the young, pharmacogenetics and relevance to multifactorial forms of type 2 diabetes

Most valuable breakthroughs in the genetics of type 2 diabetes for the past two decades have arisen from candidate gene studies and familial linkage analysis of maturity-onset diabetes of the young (MODY), an autosomal dominant form of diabetes typically occurring before 25 years of age caused by primary insulin secretion defects. Despite its low prevalence, MODY is not a single entity but presents genetic, metabolic and clinical heterogeneity. MODY can result from mutations in at least six different genes encoding the glucose sensor enzyme glucokinase and transcription factors that participate in a regulatory network essential for adult beta-cell function. Additional genes have been described in other discrete phenotypes or syndromic forms of diabetes. Whereas common variants in the MODY genes contribute very modestly to type 2 diabetes susceptibility in adults, major findings emerging from the advent of genome-wide association studies will deliver an increasing number of genes and new pathways for the pathological events of the disease.

Pancreatic ectopic fat is characterized by adipocyte infiltration and altered lipid composition

OBJECTIVE

Sustained exposure to lipids is deleterious for pancreatic islet function. This could be mediated through increased pancreatic fat following increased dietary fat and in obesity, which has implications for the onset of type 2 diabetes. The aims of this study were to determine changes in extent and composition of pancreatic, hepatic, and visceral fat in mice fed a high-fat diet (HFD, 40% by weight) compared with a control diet (5% fat) of similar fatty acid composition, and to compare composition and extent of pancreatic fat in human type 2 diabetes.

METHODS AND PROCEDURES

Mice were fed HFD for 3 or 15 weeks. Human postmortem pancreas was examined from subjects with type 2 diabetes (n = 9) and controls (n = 7). Tissue lipid content and composition were determined by gas chromatography and pancreatic adipocyte infiltration quantified by morphometry.

RESULTS

Pancreatic triacylglycerol (TG) content was 20x greater (P < 0.05) in HFD mice and there were more pancreatic perilipin-positive adipocytes compared with controls after 15 weeks. The proportions of 18:1n -9 and 18:2n -6 in pancreatic TG and the 20:4n -6/18:2n -6 ratio in phospholipids, were higher (both P < 0.05) after HFD compared with controls. Human pancreatic TG content was correlated with the proportion of pancreatic perilipin-positive adipocytes (r = 0.64, P < 0.05) and associated with unsaturated fatty acid enrichment (P < 0.05).

DISCUSSION

Adipocyte infiltration in pancreatic exocrine tissue is associated with high-fat feeding in mice and pancreatic TG content in humans. This alters the fatty acid milieu of the islet which could contribute to islet dysfunction.

Clinical implications of a molecular genetic classification of monogenic beta-cell diabetes

Monogenic diabetes resulting from mutations that primarily reduce beta-cell function accounts for 1-2% of diabetes cases, although it is often misdiagnosed as either type 1 or type 2 diabetes. Knowledge of the genetic etiology of diabetes enables more-appropriate treatment, better prediction of disease progression, screening of family members and genetic counseling. We propose that the old clinical classifications of maturity-onset diabetes of the young and neonatal diabetes are obsolete and that specific genetic etiologies should be sought in four broad clinical situations because of their specific treatment implications. Firstly, diabetes diagnosed before 6 months of age frequently results from mutation of genes that encode Kir6.2 (ATP-sensitive inward rectifier potassium channel) or sulfonylurea receptor 1 subunits of an ATP-sensitive potassium channel, and improved glycemic control can be achieved by treatment with high-dose sulfonylureas rather than insulin. Secondly, patients with stable, mild fasting hyperglycemia detected particularly when they are young could have a glucokinase mutation and might not require specific treatment. Thirdly, individuals with familial, young-onset diabetes that does not fit with either type 1 or type 2 diabetes might have mutations in the transcription factors HNF-1alpha (hepatocyte nuclear factor 1-alpha) or HNF-4alpha, and can be treated with low-dose sulfonylureas. Finally, extrapancreatic features, such as renal disease (caused by mutations in HNF-1beta) or deafness (caused by a mitochondrial m.3243A>G mutation), usually require early treatment with insulin.

Congenital and developmental pancreatic anomalies: ultrasound, computed tomography, and magnetic resonance imaging features

The purpose of this article is to provide an overview of the most common anatomic, congenital, and developmental anomalies of the pancreas. Familiarity with the imaging appearances of these anomalies as well as the range of normal appearance is important to differentiate them from other conditions, especially since some of these variants are commonly encountered. Basic knowledge of the normal embryology is of utmost importance to be able to recognize these disorders.

Pancreatic fat content and beta-cell function in men with and without type 2 diabetes

OBJECTIVE

Insulin resistance, associated with increased lipolysis, results in a high exposure of nonadipose tissue to lipids. Experimental data indicate that fatty infiltration of pancreatic islets may also contribute to beta-cell dysfunction, but whether this occurs in humans in vivo is unknown.

RESEARCH DESIGN AND METHODS

Using proton magnetic resonance spectroscopy and oral glucose tolerance tests, we studied the association of pancreatic lipid accumulation in vivo and various aspects of beta-cell function in 12 insulin-naive type 2 diabetic and 24 age- and BMI-matched nondiabetic men.

RESULTS

Patients versus control subjects had higher A1C, fasting plasma glucose, and insulin and triglyceride levels and lower HDL cholesterol, but similar waist circumference. Median (interquartile range) pancreatic fat content in patients and control subjects was 20.4% (13.4-43.6) and 9.7% (7.0-20.2), respectively (P = 0.032). Pancreatic fat correlated negatively with beta-cell function parameters, including the insulinogenic index adjusted for insulin resistance, early glucose-stimulated insulin secretion, beta-cell glucose sensitivity, and rate sensitivity (all P < 0.05), but not potentiation. However, these associations were significantly affected by the diabetic state, such that a significant association of pancreatic fat with beta-cell dysfunction was only present in the nondiabetic group (all P < 0.01), suggesting that once diabetes occurs, factors additional to pancreatic fat account for further beta-cell function decline. In control subjects, the association of pancreatic fat and beta-cell function remained significant after correction for BMI, fasting plasma glucose, and triglycerides (P = 0.006).

CONCLUSIONS

These findings indicate that pancreatic lipid content may contribute to beta-cell dysfunction and possibly to the subsequent development of type 2 diabetes in susceptible humans.

Monogenic disorders of the pancreatic β-cell: personalizing treatment for rare forms of diabetes and hypoglycemia

Over the past 10–20 years, our understanding of the genetic etiology of monogenic disorders of the pancreatic β-cell has greatly improved. This has enabled clinicians to provide patients with more accurate information regarding prognosis and inheritance and has influenced treatment. Maturity-onset diabetes of the young and neonatal diabetes are two such examples. Patients with maturity-onset diabetes of the young due to glucokinase mutations can usually be managed by diet alone, while those affected by HNF-1α and HNF-4α mutations respond well to low doses of sulfonylureas. The identification of mutations in the ATP-dependent potassium channel genes KCNJ11 and ABCC8 as the most common cause of permanent neonatal diabetes has improved treatment regimes for affected children. In addition to enabling patients to stop insulin injections, their glycemic control has also improved. These advances show the importance of unravelling the genetics of a disease to achieve the best individualized treatment for the patients affected.