Fractal-based analysis of optical coherence tomography data to quantify retinal tissue damage

BACKGROUND

The sensitivity of Optical Coherence Tomography (OCT) images to identify retinal tissue morphology characterized by early neural loss from normal healthy eyes is tested by calculating structural information and fractal dimension. OCT data from 74 healthy eyes and 43 eyes with type 1 diabetes mellitus with mild diabetic retinopathy (MDR) on biomicroscopy was analyzed using a custom-built algorithm (OCTRIMA) to measure locally the intraretinal layer thickness. A power spectrum method was used to calculate the fractal dimension in intraretinal regions of interest identified in the images. ANOVA followed by Newman-Keuls post-hoc analyses were used to test for differences between pathological and normal groups. A modified p value of <0.001 was considered statistically significant. Receiver operating characteristic (ROC) curves were constructed to describe the ability of each parameter to discriminate between eyes of pathological patients and normal healthy eyes.

RESULTS

Fractal dimension was higher for all the layers (except the GCL + IPL and INL) in MDR eyes compared to normal healthy eyes. When comparing MDR with normal healthy eyes, the highest AUROC values estimated for the fractal dimension were observed for GCL + IPL and INL. The maximum discrimination value for fractal dimension of 0.96 (standard error =0.025) for the GCL + IPL complex was obtained at a FD ≤ 1.66 (cut off point, asymptotic 95% Confidence Interval: lower-upper bound = 0.905-1.002). Moreover, the highest AUROC values estimated for the thickness measurements were observed for the OPL, GCL + IPL and OS. Particularly, when comparing MDR eyes with control healthy eyes, we found that the fractal dimension of the GCL + IPL complex was significantly better at diagnosing early DR, compared to the standard thickness measurement.

CONCLUSIONS

Our results suggest that the GCL + IPL complex, OPL and OS are more susceptible to initial damage when comparing MDR with control healthy eyes. Fractal analysis provided a better sensitivity, offering a potential diagnostic predictor for detecting early neurodegeneration in the retina.

Automated classifiers for early detection and diagnosis of retinopathy in diabetic eyes

BACKGROUND

Artificial neural networks (ANNs) have been used to classify eye diseases, such as diabetic retinopathy (DR) and glaucoma. DR is the leading cause of blindness in working-age adults in the developed world. The implementation of DR diagnostic routines could be feasibly improved by the integration of structural and optical property test measurements of the retinal structure that provide important and complementary information for reaching a diagnosis. In this study, we evaluate the capability of several structural and optical features (thickness, total reflectance and fractal dimension) of various intraretinal layers extracted from optical coherence tomography images to train a Bayesian ANN to discriminate between healthy and diabetic eyes with and with no mild retinopathy.

RESULTS

When exploring the probability as to whether the subject's eye was healthy (diagnostic condition, Test 1), we found that the structural and optical property features of the outer plexiform layer (OPL) and the complex formed by the ganglion cell and inner plexiform layers (GCL + IPL) provided the highest probability (positive predictive value (PPV) of 91% and 89%, respectively) for the proportion of patients with positive test results (healthy condition) who were correctly diagnosed (Test 1). The true negative, TP and PPV values remained stable despite the different sizes of training data sets (Test 2). The sensitivity, specificity and PPV were greater or close to 0.70 for the retinal nerve fiber layer's features, photoreceptor outer segments and retinal pigment epithelium when 23 diabetic eyes with mild retinopathy were mixed with 38 diabetic eyes with no retinopathy (Test 3).

CONCLUSIONS

A Bayesian ANN trained on structural and optical features from optical coherence tomography data can successfully discriminate between healthy and diabetic eyes with and with no retinopathy. The fractal dimension of the OPL and the GCL + IPL complex predicted by the Bayesian radial basis function network provides better diagnostic utility to classify diabetic eyes with mild retinopathy. Moreover, the thickness and fractal dimension parameters of the retinal nerve fiber layer, photoreceptor outer segments and retinal pigment epithelium show promise for the diagnostic classification between diabetic eyes with and with no mild retinopathy.

[Hearing impairment and tinnitus in patients with type 2 diabetes]

INTRODUCTION

Hearing impairment is one of the most frequent chronic health issue. The incidence of hearing impairment and tinnitus increases with age.

AIM

The aim of the authors was to determine the prevalence of hearing impairment and tinnitus in type 2 diabetic patients and to examine the possible associations between hearing impairment and/or tinnitus and increased HbA1c levels.

METHODS

103 patients with type 2 diabetes (47 men, 56 women; age, 61.6±10.3 years, mean±SD; range, 33-88 years) evaluated at the 2nd Department of Medicine, Semmelweis University were enrolled in this study and the results were compared to those obtained from 589 type 2 diabetic (253 men, 336 women; age, 55.4±11.0 years, mean±SD; range, 26-97 years) and 15 622 non-diabetic patients (7002 men, 8620 women; age, 55.1±11.1 years, mean±SD; range, 26-98 years) who participated in a comprehensive health screening programme in Hungary. Hearing impairment was determined using the Interacoustics model AS608 screening audiometer in all patient groups. Tinnitus was evaluated with questionnaire.

RESULTS

It was found that hearing impairment and/or tinnitus occurred in a very high proportion of type 2 diabetic patients evaluated at the 2nd Department of Medicine, Semmelweis University (80% of cases) as compared to type 2 diabetic (34% of cases) and non-diabetic patients (14% of cases) enrolled in the national health screening programme. There was no significant correlation between increased HbA1c levels and hearing impairment or tinnitus in type 2 diabetic patients.

CONCLUSION

These results suggest that the prevalence of hearing impairment and tinnitus is higher and develop at an earlier age in patients with type 2 diabetes. The results indicate a high prevalence of hearing impairment and tinnitus in type 2 diabetic patients.

[Oral antidiabetic drugs in chronic renal disease]

Decline in renal function may increase plasma concentration of several drugs - including oral antidiabetics - with a possible need for dose adjustment in this patient population. In this review, the pathophysiology and progression of diabetic kidney diseases is summarized. Guidance is given about appropriate administration of oral antidiabetic drugs in chronic kidney diseases, based on approved product label information. In addition to pioglitazon, recent availability of the new dipeptidyl peptidase-4 inhibitor linagliptin provides another option for diabetic patients with renal impairment without the need for dose reduction due to its predominant enterohepatic elimination.

Formation of amino acids and nucleotide bases in a Titan atmosphere simulation experiment

The discovery of large (>100 u) molecules in Titan's upper atmosphere has heightened astrobiological interest in this unique satellite. In particular, complex organic aerosols produced in atmospheres containing C, N, O, and H, like that of Titan, could be a source of prebiotic molecules. In this work, aerosols produced in a Titan atmosphere simulation experiment with enhanced CO (N(2)/CH(4)/CO gas mixtures of 96.2%/2.0%/1.8% and 93.2%/5.0%/1.8%) were found to contain 18 molecules with molecular formulae that correspond to biological amino acids and nucleotide bases. Very high-resolution mass spectrometry of isotopically labeled samples confirmed that C(4)H(5)N(3)O, C(4)H(4)N(2)O(2), C(5)H(6)N(2)O(2), C(5)H(5)N(5), and C(6)H(9)N(3)O(2) are produced by chemistry in the simulation chamber. Gas chromatography-mass spectrometry (GC-MS) analyses of the non-isotopic samples confirmed the presence of cytosine (C(4)H(5)N(3)O), uracil (C(5)H(4)N(2)O(2)), thymine (C(5)H(6)N(2)O(2)), guanine (C(5)H(5)N(5)O), glycine (C(2)H(5)NO(2)), and alanine (C(3)H(7)NO(2)). Adenine (C(5)H(5)N(5)) was detected by GC-MS in isotopically labeled samples. The remaining prebiotic molecules were detected in unlabeled samples only and may have been affected by contamination in the chamber. These results demonstrate that prebiotic molecules can be formed by the high-energy chemistry similar to that which occurs in planetary upper atmospheres and therefore identifies a new source of prebiotic material, potentially increasing the range of planets where life could begin.

[Type 1 diabetes mellitus: most recent advances in its pathogenesis and treatment]

The incidence and prevalence of diabetes mellitus is globally increasing. The causes of this trend are relatively obvious in the case of type 2 diabetes. In contrast, in case of type 1 diabetes the amount of available data is continuously growing, but the causes are not so well defined. The genetic risk, especially related to the MHC genes is well known, and the increasing amount of data underlines the role of additional risks due to non-MHC genetic polimorphisms. Hopefully, they will provide the basis for future diagnostic and therapeutic approaches. There is increasing knowledge about the pathophysiological aspects including the role of immunological disregulation (balance of autotolerance, role of regulatory T-cells) and environmental triggers (nutrients, viruses). Information on the entero-insular axis and the β-cell protective role of incretin hormones might offer an opportunity for new therapeutic strategies. In this paper, the authors try to summarize some current aspects of the pathomechanism and related therapeutic approaches.

[Changes in cognitive function in patients with diabetes mellitus]

Patients with diabetes are approximately 1.5 times more likely to experience cognitive decline than individuals without diabetes mellitus. Most of the data suggest that patients with diabetes have reduced performance in numerous domains of cognitive function. In patients with type 1 diabetes, specific and global deficits involving speed of psychomotor efficiency, information processing, mental flexibility, attention, and visual perception seem to be present, while in patients with type 2 diabetes an increase in memory deficits, a reduction in psychomotor speed, and reduced frontal lobe (executive) functions have been found. The complex pathophysiology of changes in the central nervous system in diabetes has not yet been fully elucidated. It is important to consider the patient's age at the onset of diabetes, the glycemic control status, and the presence of diabetic complications. Neurological consequences of diabetes appear parallel to those observed in the aging brain. Neuroimaging studies highlight several structural cerebral changes, cortical and subcortical atrophy, beside increased leukoaraiosis that occurs in association with diabetes. There is supporting evidence from many hypotheses to explain the pathophysiology of cognitive decline associated with diabetes. The main hypotheses pointing to the potential, implied mechanisms involve hyperglycemia, hypoglycemia, microvascular disease, insulin resistance, hyperinsulinism, hyperphosphorylation of tau protein, and amyloid-β deposition.

Preserved structural and functional characteristics of common carotid artery in properly treated normoglycemic women with gestational diabetes mellitus

Women with gestational diabetes mellitus (GDM) are at high risk of subsequently developing type 2 diabetes mellitus which is an important cardiovascular risk factor. We have evaluated whether preclinical morphological and functional arterial changes are present in GDM. Diameter, intima-media thickness (IMT), intima-media cross-section area (IMCSA) and elasticity features (compliance, distensibility coefficient, circumferential strain, stiffness index (SI) α and β, incremental elastic modulus) of the common carotid arteries (CCA) were studied in the 3rd trimester in 25 women with GDM, and 17 normal pregnant women matched for age and body mass index using an ultrasonographic vessel wall-movement tracking system and applanation tonometry. Mean IMT, IMCSA and SI α tended to be larger, whereas compliance was smaller in women with GDM but none of these differences were significant. Serum glucose (4.99 ± 0.51 vs. 4.79 ± 0.61 mmol/L, p=0.37) and HbA1c (5.33 ± 0.27 vs. 5.36 ± 0.47 mmol/L, p=0.85) proved normoglycemia in both groups. In conclusion, by the combination of methods we applied in this case control study, neither morphological nor functional characteristics of large elastic arteries differ significantly between well-treated normoglycemic women with GDM and non-diabetic pregnant women in the 3rd trimester.

[Clinical aspects of the link between diabetes and depression]

Diabetes mellitus and depression are public health concerns of the present and, as predicted, also the future. The observation that depression is seen more frequently in diabetic patients compared to the non-diabetic population has been proven by several recent studies. The co-occurrence carries further risks for the affected patients, as depression in diabetics may affect sufficient treatment of diabetes and enhance the development of diabetic complications. These may further worsen depressive symptoms causing a vicious cycle in these patients. In the present paper authors discuss in detail the theoretic and practical issues of the complex two directional relationships between diabetes and depression. Their goal is to draw attention to depression as co-morbidity of diabetes that may interfere with the optimization of diabetic patient's carbohydrate metabolism. If sufficient glycaemic control is not achieved using routine clinical methods depression should be evaluated as a probable cause. If needed, depression should be treated to improve the medical outcomes and quality of life of diabetic patients.

Diabetes and thyroid disorders

Both diabetes mellitus and thyroid disorders are common diseases. According to epidemiologic studies the prevalence of specific thyroid disorders in diabetic subjects is two times higher. Risk factors are age, female gender and autoimmune diabetes mellitus. However, thyroid disorders are diagnosed only half of the cases in diabetic population. The review briefly summarizes the association of autoimmune diabetes mellitus and thyreoiditis, the risk of thyroid disorders in type 1 diabetic pregnant women. Furthermore, the influence of obesity in the risk on thyroid cancer and the effect of glucagon-like peptide 1 analogue on thyroid medullary C-cells are discussed. Orv. Hetil., 2011, 152, 516–519.

Safety and efficacy of rituximab in nonviral cryoglobulinemia vasculitis: data from the French Autoimmunity and Rituximab registry

OBJECTIVE

Management of nonviral cryoglobulinemia vasculitis has yet to be defined. Rituximab has emerged as a novel and promising therapeutic alternative, but data are scarce. Our objective was to evaluate the safety and efficacy of rituximab in nonviral cryoglobulinemia vasculitis in off-trial real-life patients.

METHODS

Prospective data from the French AutoImmunity and Rituximab (AIR) registry, which includes data on patients with autoimmune disorders treated with rituximab in off-label conditions, were analyzed.

RESULTS

Twenty-three patients received treatment with rituximab for cryoglobulinemia vasculitis. Tolerance was marked by the occurrence of side effects in almost half of the patients, including severe infections in 6 (26%) of 23, with a rate of 14.1 per 100 patient-years. These infections occurred in a particular subset of patients ages>70 years, with essential type II mixed cryoglobulinemia and renal failure with a glomerular filtration rate of <60 ml/minute, and receiving high-dose corticosteroids. Three of these patients died. In contrast, clinical and immunologic efficacy was noted in all evaluable patients. Clinical relapses occurred in half of the patients after a median time of 13.5 months following rituximab administration, and were more frequent in patients refractory to previous immunosuppressive therapy than in previously untreated patients.

CONCLUSION

Data from the AIR registry show a dramatic efficacy and a steroid-sparing effect of rituximab, but also show the occurrence of severe infections in elderly patients with renal failure and high-dose steroids. The role of rituximab in nonviral cryoglobulinemia vasculitis remains to be defined in well-designed randomized controlled trials.

Evolution and predictors of morphological and functional arterial changes in the course of type 1 diabetes mellitus

BACKGROUND

Diabetes mellitus results in accelerated atherosclerosis. We evaluated preclinical, morphological and functional vascular changes in type 1 diabetes mellitus.

METHODS

Diameter, intima-media thickness, intima-media cross-section area, and elasticity features (compliance, distensibility coefficient, circumferential strain, stiffness index, incremental elastic modulus) of the common carotid arteries and carotid-femoral pulse wave velocity were studied in 42 patients with type 1 diabetes mellitus without macroangiopathy, and 41 control subjects matched for sex, age and body mass index using an ultrasonographic vessel wall-movement tracking system and applanation tonometry.

RESULTS

Significantly larger intima-media thickness (523 ± 55 versus 567 ± 89 µm, p < 0.01), intima-media cross-section area (11.60 ± 1.81 versus 13.08 ± 3.02 mm(2) , p < 0.01), SI (5.58 ± 1.24 versus 7.08 ± 2.69, p < 0.01) and pulse wave velocity (6.00 ± 0.82 versus 6.61 ± 1.56 m/s, p < 0.05) were found in type 1 diabetes mellitus patients compared to controls. When type 1 diabetes mellitus patients with short and long disease duration (≤ or > 10 years) were compared, diameter (6450 ± 433 versus 6847 ± 750 µm, p < 0.05), intima-media cross-section area (11.97 ± 1.98 versus 14.01 ± 3.43 mm, p < 0.05) and pulse wave velocity (5.90 ± 0.92 versus 7.20 ± 1.74 m/s, p < 0.01) differed significantly. When multivariate analyses were restricted to type 1 diabetes mellitus patients, age was an independent predictor of stiffness index and pulse wave velocity, the duration of diabetes mellitus of intima-media cross-section area and pulse wave velocity, systolic blood pressure of diameter and pulse wave velocity, and low-density lipoprotein-cholesterol of intima-media thickness, intima-media cross-section area and stiffness index.

CONCLUSIONS

There are differences in the time course of evolution and in predictors of morphological and functional changes in arteries in type 1 diabetes mellitus.

Elevated serum dipeptidyl peptidase-4 activity in type 1 diabetes mellitus: a direct comparison

A dipeptidil-peptidáz-4 enzim – amely azonos a T-lymphocyta membránfelszínhez kötött CD26 molekulával – az inkretin hormonok bontásával jelentős szerepet játszik a szénhidrát-anyagcsere szabályozásában. Célkitűzés: Vizsgálatunk célja az volt, hogy meghatározzuk az éhomi és postprandialis szérum-DPP-4 enzimaktivitását 41 1-es, 87 2-es típusú cukorbetegben, valamint 25 egészséges személyben. Módszer: A szérum-DPP-4-enzimaktivitás meghatározása microplate-alapú kinetikus eljárással történt éhomi, majd étkezést követően 60 és 120 perces időszakokban. Eredmények: A DPP-4-enzimaktivitás mind éhomi, mind postprandialis állapotban szignifikánsan magasabb volt az 1-es típusú diabetesben szenvedőknél, mint a 2-es típusú diabeteses vagy a kontrollszemélyekben. Nem találtunk változást az enzimaktivitásban egyik csoporton belül sem a postprandialis és az éhomi állapot között. Nem volt korreláció sem az éhomi plazmaglükóz- és a szérum-DPP-4-enzimaktivitás, sem a HbA 1c és a szérum-DPP-4-enzimaktivitás között. Következtetés: Eredményeink felvetik annak a valószínűségét, hogy a DPP-4-gyel kapcsolatba hozható vércukorszint-változás nem a szérumban mérhető DPP-4-aktivitás-változás következménye, hanem parakrin módon ható DPP-4-hatásként jelentkezik. Az 1-es típusú diabetesben észlelhető emelkedett DPP-4-enzimaktivitás ugyanakkor a pancreas autoimmun folyamatára utalhat, de hormonális feed-back mechanizmust, esetleg célszervkárosodást is jelezhet.