Maternally inherited diabetes and deafness: a multicenter study

BACKGROUND

Maternally inherited diabetes and deafness (MIDD), which is seen in 0.5% to 2.8% of patients with type 2 diabetes mellitus, is related to a point mutation at position 3243 of mitochondrial (mt) DNA. Its clinical description is incomplete.

OBJECTIVE

To study the clinical presentation and complications of diabetes in patients with MIDD and to identify clinical characteristics that may help select diabetic patients for mtDNA mutation screening.

DESIGN

Multicenter prospective descriptive study.

SETTING

16 French departments of internal medicine, diabetes and metabolic diseases, or both.

PATIENTS

54 patients with type 2 diabetes mellitus and the mtDNA 3243 mutation.

MEASUREMENTS

Characteristics of diabetes, metabolic control (glycosylated hemoglobin level), complications of diabetes, and involvement of other organs.

RESULTS

On average, patients with MIDD were young at diabetes onset and presented with a normal or low body mass index. None were obese. Seventy-three percent of probands had a maternal family history of diabetes. Diabetes was non-insulin-dependent at onset in 87% of patients; however, 46% of patients had non-insulin-dependent disease at onset but progressed to insulin therapy after a mean duration of approximately 10 years. Neurosensory hearing loss was present in almost all patients. Eighty-six percent of patients who received an ophthalmologic examination had macular pattern dystrophy (a specific retinal lesion). Forty-three percent of patients had myopathy, 15% had cardiomyopathy, and 18% (9 of 51) had neuropsychiatric symptoms. Although the prevalence of diabetic retinopathy was 8% among patients who received an ophthalmologic examination, lower than expected after a mean 12-year duration of diabetes, prevalence of kidney disease was 28%. This suggests that a specific renal involvement was the result of mitochondrial disease.

CONCLUSIONS

Maternally inherited diabetes and deafness has a specific clinical profile that may help identify diabetic patients for mtDNA testing.

Three-dimensional reconstruction of painted human interphase chromosomes: active and inactive X chromosome territories have similar volumes but differ in shape and surface structure

This study provides a three-dimensional (3D) analysis of differences between the 3D morphology of active and inactive human X interphase chromosomes (Xa and Xi territories). Chromosome territories were painted in formaldehyde-fixed, three-dimensionally intact human diploid female amniotic fluid cell nuclei (46, XX) with X-specific whole chromosome compositive probes. The colocalization of a 4,6-diamidino-2-phenylindole dihydrochloride-stained Barr body with one of the two painted X territories allowed the unequivocal discrimination of the inactive X from its active counterpart. Light optical serial sections were obtained with a confocal laser scanning microscope. 3D-reconstructed Xa territories revealed a flatter shape and exhibited a larger and more irregular surface when compared to the apparently smoother surface and rounder shape of Xi territories. The relationship between territory surface and volume was quantified by the determination of a dimensionless roundness factor (RF). RF and surface area measurements showed a highly significant difference between Xa and Xi territories (P < 0.001) in contrast to volume differences (P > 0.1). For comparison with an autosome of similar DNA content, chromosome 7 territories were additionally painted. The 3D morphology of the chromosome 7 territories was similar to the Xa territory but differed strongly from the Xi territory with respect to RF and surface area (P < 0.001).

Measurement of visceral adipose tissue by DXA combined with anthropometry in obese humans

OBJECTIVE

To get accurate measurements of visceral adipose tissue (VAT) using dual energy X-ray absorptiometry (DXA).

DESIGN

DXA and anthropometric data and their combinations were compared to the VAT area calculated from a computed tomography (CT) single scan.

SUBJECTS

71 overweight subjects (44 women, 27 men), age: 16-70 y, BMI: 27-52 kg/m2.

MEASUREMENTS

Total body and segmental tissue composition, and new parameters obtained from DXA, in addition to waist and hip circumferences and abdominal sagittal diameter measurements.

RESULTS

The ratio measured at the umbilical level (sagittal diameter - subcutaneous fat width) x (transverse internal diameter)/(height) was closely related to VAT (r=0.94 for women and 0.88 for men). It gave the most predictive equation for VAT: y = 79.6x (s.e. 3.9) - 149 cm2 for the whole population (r2=0.86, P<0.0001, root mean square error=38.2 cm2. An independent relationship between lean mass or its index (r=0.52 and 0.72, P<0.001) and VAT was also found in women.

CONCLUSION

This study demonstrates the potential usefulness of DXA to supply accurate measurements of VAT in addition to total body composition determination in obese subjects.

The clinical variability of maternally inherited diabetes and deafness is associated with the degree of heteroplasmy in blood leukocytes

CONTEXT

Maternally inherited diabetes and deafness (MIDD) is a rare form of diabetes with a matrilineal transmission, sensorineural hearing loss, and macular pattern dystrophy due to an A to G transition at position 3243 of mitochondrial DNA (mtDNA) (m.3243A>G). The phenotypic heterogeneity of MIDD may be the consequence of different levels of mutated mtDNA among mitochondria in a given tissue.

OBJECTIVE

The aim of the present study was thus to ascertain the correlation between the severity of the phenotype in patients with MIDD and the level of heteroplasmy in the blood leukocytes.

PARTICIPANTS

The GEDIAM prospective multicenter register was initiated in 1995. Eighty-nine Europid patients from this register, with MIDD and the mtDNA 3243A>G mutation, were included. Patients with MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) or with mitochondrial diabetes related to other mutations or to deletions of mtDNA were excluded.

RESULTS

A significant negative correlation was found between levels of heteroplasmy and age of the patients at the time of sampling for molecular analysis, age at the diagnosis of diabetes, and body mass index. After adjustment for age at sampling for molecular study and gender, the correlation between heteroplasmy levels and age at the diagnosis of diabetes was no more significant. The two other correlations remained significant. A significant positive correlation between levels of heteroplasmy and HbA(1c) was also found and remained significant after adjustment for age at molecular sampling and gender.

CONCLUSIONS

These results support the hypothesis that heteroplasmy levels are at least one of the determinants of the severity of the phenotype in MIDD.

Protection from insulin-dependent diabetes mellitus is linked to a peptide transporter gene

HLA class II association with insulin-dependent diabetes mellitus (IDDM) is well established but is still difficult to map to a particular locus. Polymorphism of the genes coding for transporter associated with antigen processing (TAP1 and TAP2), and located in the HLA class II region, was studied in 167 IDDM patients (116 adult-onset and 51 childhood-onset patients) and 98 normal controls using oligotyping after genomic amplification. A dominant protective effect was observed for the TAP2*0201 allele [relative risk (RR) = 0.3, corrected probability (pc) < 0.001]. Conversely, susceptibility to IDDM was associated with apparent homozygosity for the TAP2*0101 allele (RR = 3.4, pc < 0.001). Protection was independent from but additive to the protection conferred by the DRB1*02 DQB1*0602 haplotype (RR = 0.06, pc < 0.05), and antagonistic to the DRB1*03 DQB1*0201 and DRB1*04 DQB1*0302 haplotypes predisposing effect (RR = 1.1, not significant), arguing in favor of an absence of linkage disequilibrium between TAP2 and HLA class II genes. This was assessed by chi 2 analysis. TAP1 allelic distribution was not different among diabetics and controls. A significant association was observed between the presence of TAP2*0101 and that of islet cell antibodies (p < 0.05). These data suggest that the TAP2 gene, which encodes protein required for delivery of antigen peptides to class I molecules in the endoplasmic reticulum, could modulate the autoimmune response leading to beta cell destruction. From a practical point of view, they make the combined screening of HLA class II and TAP2 loci a highly valuable tool in IDDM prediction.

Evaluation of dual-energy X-Ray absorptiometry for body-composition assessment in rats

Recent developments in dual-energy X-ray absorptiometry (DXA) have rendered feasible the determination of whole-body composition in small laboratory animals by directly measuring fat, fat-free and mineral bone masses. Our aim was to evaluate this technique by cross-calibrating the DXA method with the carcass chemical analysis in a heterogeneous population of nondiabetic Wistar and diabetic GK rats (21 animals were used for precision error and reproducibility determinations and 26 were used for accuracy studies). We report that this technique is optimized for weights >200 g. The respective CV for lean mass, fat mass and percentage of fat mass determined in short-term or transversal studies was 1.1 +/- 0.1, 3.0 +/- 1.3 and 3. 1 +/- 0.4% (mean +/- SD) respectively. Further, this technique is valid for rats weighing from 130 to 200 g by using three successive scans. In longitudinal studies, daily calibrations significantly increased the percentage of fat mass CV to 6.6 +/- 3.3%, but it was significantly decreased to 3.0 +/- 2.7% by the use of triplicate scans. The accuracy for DXA was excellent in reference to the chemical extraction technique (r2 = 0.95 for percentage of fat mass, P < 0.0001), using an adjustment factor of 0.75 (limits of agreement between the two methods for percentage of fat mass = -1.7-2.3%). Mimicry of longitudinal changes in body composition with intraperitoneal injections of saline solution demonstrated a satisfactory detection of body component changes (</=2% of error for each final component analyzed, when increasing total lean mass by 11. 8%). We conclude that DXA is appropriate for rat whole-body composition determination, allowing reliable long-term follow-up of individual animals for the first time.

Fear of hypoglycaemia in patients with type 1 diabetes: do patients and diabetologists feel the same way?

AIM

This study described and compared the perception of hypoglycaemia in both patients with type 1 diabetes and diabetologists.

METHODS

This was an observational cross-sectional study undertaken in France in 2011. Data for what hypoglycaemia represents and practices related to it were collected using a questionnaire completed by patients with type 1 diabetes (all>12 years of age) and their diabetologists. Agreement between patients and physicians was evaluated by the intraclass correlation coefficient (ICC) and Gwet's coefficient (GC).

RESULTS

A total of 485 patients were enrolled by 118 diabetologists. Half the patients thought that hypoglycaemia was always symptomatic. According to both patients and diabetologists, hypoglycaemia impaired quality of life, caused anxiety and was disturbing, especially at night. Clinical symptoms of hypoglycaemia (sweating, shakiness, anxiety) were linked to patient's age and diabetes duration. Regarding hypoglycaemia frequency, agreement was good for severe hypoglycaemia (GC: 0.61 and 0.72 for diurnal and nocturnal hypoglycaemia, respectively) and poor for mild hypoglycaemia (ICC: 0.44 and 0.40, respectively). Diabetologists correctly evaluated the impact of hypoglycaemia on quality of life, but overestimated the hypoglycaemia-induced burden and anxiety. Counteractive behaviours were frequent: 23% of patients decreased their insulin dose, 20% increased their sugar intake and 12% ate extra snacks. Diabetologists were generally aware of these measures, but not of how often patients used them.

CONCLUSION

Diabetologists and patients do not share enough information about hypoglycaemia. Fear of hypoglycaemia and counteractive behaviours should be looked for by diabetologists. Systematic advice and specially adapted education should also be provided to increase patients' awareness of hypoglycaemia.

Improvement of diaphragmatic performance through orthotopic application of decellularized extracellular matrix patch

Muscle tissue engineering can provide support to large congenital skeletal muscle defects using scaffolds able to allow cell migration, proliferation and differentiation. Acellular extracellular matrix (ECM) scaffold can generate a positive inflammatory response through the activation of anti-inflammatory T-cell populations and M2 polarized macrophages that together lead to a local pro-regenerative environment. This immunoregulatory effect is maintained when acellular matrices are transplanted in a xenogeneic setting, but it remains unclear whether it can be therapeutic in a model of muscle diseases. We demonstrated here for the first time that orthotopic transplantation of a decellularized diaphragmatic muscle from wild animals promoted tissue functional recovery in an established atrophic mouse model. In particular, ECM supported a local immunoresponse activating a pro-regenerative environment and stimulating host muscle progenitor cell activation and migration. These results indicate that acellular scaffolds may represent a suitable regenerative medicine option for improving performance of diseased muscles.

Heterogeneity of diabetes phenotype in patients with 3243 bp mutation of mitochondrial DNA (Maternally Inherited Diabetes and Deafness or MIDD)

OBJECTIVE

In patients with maternally inherited diabetes and deafness (MIDD), due to 3 243 A > G mutation of mitochondrial DNA (mtDNA), diabetes may present with variable phenotypes.

OBJECTIVE

To ascertain the existence of two distinct phenotypes, MIDD1 and MIDD2, in a series of patients with MIDD.

DESIGN

Multicenter prospective study.

PATIENTS

77 patients with diabetes and the mtDNA 3243 mutation and 139 control patients with type 1 (T1D) or type 2 (T2D) diabetes, matched according to initial presentation of diabetes, age at onset, sex, and duration of diabetes (24 T1D and 115 T2D, including 55 treated with insulin).

MEASUREMENTS

Anthropometric characteristics (height, body weight, body mass index [BMI], sex), family history of diabetes, and characteristics of diabetes (age at onset, treatment, hemoglobin A1c [HbA1c]), extrapancreatic manifestations.

RESULTS

In 13 cases (17%, MIDD1), diabetes presented as insulin-dependent from the onset, with ketoacidosis in 6 cases. In 64 cases (83%, MIDD2), diabetes resembled T2D, and was treated with diet in 12 cases, oral hypoglycemic agents in 21 cases, or insulin in 31 cases. Compared with patients with MIDD2, patients with MIDD1 were characterized by lower age at onset of first manifestation of MIDD (25.4 +/- 9.6 vs 33.7 +/- 13.2 Years, P<0.0005), lower body weight (49.1 +/- 7.4 vs 56.3 +/- 10.9 kg, P<0.0025), lower BMI (18.2 +/- 2.3 vs 20.9 +/- 3.6 kg/m2, P<0.0005), and higher HbA1c levels (9.5 +/- 2.0 vs 7.5 +/- 1.6%, P<0.0005). Frequency of family history of diabetes and of extrapancreatic manifestations was the same in both MIDD subtypes. No difference was found within the MIDD2 subtype when comparing patients treated with or without insulin. Compared with matched controls, patients with MIDD had a lower BMI (MIDD1/T1D 18.2 +/- 2.3 vs 24.0 +/- 3.6 kg/m2 and MIDD2/T2D 20.9 +/- 3.6 vs 30.2 +/- 5.9 kg/m2, P<0.0025). Lastly, male patients with MIDD had a shorter height than controls (MIDD1/T1D: 166.1 +/- 3.2 vs 177.3 +/- 6.6 cm and MIDD2/T2D: 168.4 +/- 7.2 vs 173.6 +/- 6.6 cm P<0.025).

CONCLUSIONS

These results confirm the existence of two different phenotypes in MIDD, MIDD1 and MIDD2, which may be related to the severity of the mitochondrial disease. The role of other genetic and/or environmental factors in the variable phenotype of MIDD remains to be elucidated.

Pictorial cues and three-dimensional information processing in early infancy

Adults derive 3-D information from 2-D images by initially processing local line junction cues and then combining information from many junctions. Prior research indicates that 3-month-olds are sensitive to 3-D cues in individual line junctions. In Experiment 1, we examined whether infants are sensitive to holistic combinations of line junctions that adults use to derive overall 3-D structure. Infants detected a misoriented shape in an array depicting 3-D blocks but not in 2-D patterns that contained all of the trilinear junctions of the 3-D shapes but without the connecting lines. Thus, like adults, infants exhibited sensitivity to holistic combinations of line junctions rather than to individual junctions. In Experiment 2, when confronted with two test patterns, one containing an individual novel element among 15 familiar elements and the other containing a single familiar element among 15 novel elements, infants preferred to look at the former pattern in the 3-D condition but at the latter pattern in the 2-D condition. Thus, akin to pop-out in adults, discrepancies in 3-D cues selectively engaged infants' attention. These results suggest that 3-month-olds are not only sensitive to holistic combinations of line junctions that adults use to derive 3-D information but also selectively attend to these 3-D cues in static images.

Application of confocal laser microscopy and three-dimensional Voronoi diagrams for volume and surface estimates of interphase chromosomes

This study demonstrates the use of Voronoi tessellation procedures to obtain quantitative morphological data for chromosome territories in the cell nucleus. As a model system, chromosomes 7 and X were visualized in human female amniotic fluid cell nuclei by chromosomal in situ suppression hybridization with chromosome-specific composite probes. Light optical serial sections of 18 nuclei were obtained with a confocal scanning laser fluorescence microscope. A three-dimensional (3-D) tessellation of the image volumes defined by the stack of serial sections was then performed. For this purpose a Voronoi diagram, which consists of convex polyhedra structured in a graph environment, was built for each nucleus. The chromosome territories were extracted by applying the Delaunay graph, the dual of the Voronoi diagram, which describes the neighbourhood in the Voronoi diagram. The chromosome territories were then described by three morphological parameters, i.e. volume, surface area and a roundness factor (shape factor). The complete evaluation of a nucleus, including the calculation of the Voronoi diagram, 3-D visualization of extracted territories using computer graphic methods and parameterization was carried out on a Silicon Graphics workstation and was generally completed within 5 min. The geometric information obtained by this procedure revealed that both X- and 7-chromosome territories were similar in volume. Roundness factors indicated a pronounced variability in interphase shape for both pairs of chromosomes. Surface estimates showed a significant difference between the two X-territories but not between chromosome 7-territories.