[Aminoguanidine prevents peroxynitrite production and cardiac hypertrophy in streptozotocin-induced diabetic rats]

The effect and possible mechanisms of action of aminoguanidine (a preferential iNOS inhibitor) has been studied on cardiovascular damages and overproduction of reactive nitrogen species in streptozotocin-induced diabetic rats.

MATERIALS AND METHODS

40 rats were divided into five groups (control and diabetic, with or without aminoguanidine treatment, diabetic with insulin treatment) and oxidative stress parameters were examined. Tissue nitric oxide levels were determined by EPR spectroscopy, while peroxynitrite generation by a chemiluminescence method. Cardiac hypertrophy, blood metabolic parameters (blood glucose, HbA1c, fructosamine), as well as tissue protein carbonyl levels were also determined.

RESULTS

Diabetic animals showed increased nitric oxide and peroxynitrite generation in the aorta along with a significant hypertrophy and protein carbonylation of the cardiac tissue. Both aminoguanidine and insulin treatment suppressed high levels of nitric oxide and peroxynitrite in the vasculature, but only aminoguanidine was able to prevent hypertrophic alterations and to reduce protein carbonylation in the heart.

CONCLUSIONS

The results show that (1) aminoguanidine reduces nitric oxide production and prevents cardiac hypertrophy, (2) insulin therapy improves carbohydrate metabolism, reduces nitrosative stress but has no effect on cardiac hypertrophy. Cardiac hypertrophy in diabetes is strongly correlated with non-enzymatic glycation. Aminoguanidine prevented hypertrophy by blocking the formation of advanced glycation end products rather than via other mechanisms.

Effects of strontium on the physicochemical characteristics of hydroxyapatite

In a previous experimental study using a chronic renal failure rat model, a dose-related multiphasic effect of strontium (Sr) on bone formation was found that could be reproduced in an in vitro set-up using primary rat osteoblasts. The results from the latter study allowed us to distinguish between a reduced nodule formation in the presence of an intact mineralization at low Sr-doses (1 microg/ml) and an interference of the element with the hydroxyapatite (HA) formation at high doses (20-100 microg/ml). To further investigate the latter effect of Sr on physicochemical bone mineral properties, an in vitro study was set up in which the UMR-106 rat osteosarcoma cell line was exposed to Sr, added to the cell culture medium in a concentration range varying between 0-100 microg/ml. Temporal growth and functionality of the culture was investigated by measurement of the alkaline phosphatase activity and calcium (Ca) concentration in the culture medium (used as an index of Ca-incorporation, i.e., HA formation) at various time points. At the end of the culture period (14 days post-confluence), samples of the mineralized cultures were taken for further analysis using X-ray diffraction (XRD) and Fourier Transform Infra-Red Spectroscopy (FTIR). Synthetic HA doped with various Sr concentrations (based on the cell culture and previous experimental studies and yielding Sr/(Sr + Ca) ratios ranging from 0-60%), was prepared and examined for crystal growth and solubility. Crystal size was assessed using scanning electron microscopy (SEM). Ca incorporation indicated a reduced mineralization in the 20 and 100 microg/ml Sr groups vs. controls. Sr-doped synthetic HA showed a significant dose-dependent reduction in crystal growth, as assessed by SEM, and an increase in solubility, apparent from 12.7% Sr/(Sr + Ca) on. Moreover, in both mineralized cultures and synthetic HA, XRD and FTIR analysis showed a reduced crystallinity and altered crystal lattice at similar concentrations. These new data support our previous in vivo and in vitro findings and point to a potential physicochemical interference of Sr with HA formation and crystal properties in vivo.

Quantification of Single Fluid Inclusions by Combining Synchrotron Radiation-Induced μ-X-ray Fluorescence and Transmission

Fluid inclusions represent the only direct samples of ancient fluids in many crustal rocks; precise knowledge of their chemical composition provides crucial information to model paleofluid-rock interactions and hydrothermal transport processes. Owing to its nondestructive character, micrometer-scale spatial resolution, and high sensitivity, synchrotron radiation-induced micro-X-ray fluorescence has received great interest for the in situ multielement analysis of individual fluid inclusions. Major uncertainties associated with the quantitative analysis of single fluid inclusions arise from the inclusion depth and the volume of fluid sampled by the incident beam. While the depth can be extracted directly from the fluorescence spectrum, its volume remains a major source of uncertainty. The present study performed on natural and synthetic inclusions shows that the inclusion thickness can be accurately evaluated from transmission line scans. Experimental data matched numerical simulations based on an elliptical inclusion geometry. However, for one nonelliptical inclusion, the experimental data were confirmed using a computed absorption tomography reconstruction. Good agreement between the imaging and scanning techniques implies that the latter provides reliable fluid thickness values independent of the shape of the inclusion. Taking into consideration the incident angle, the incident beam energy, the inclusion fluid salinity, and the transmission measurement stability resulted in errors of 0.3-2 microm on calculated fluid inclusion thicknesses.

Effect of vitamin E on carotid artery elasticity and baroreflex gain in young, healthy adults

In this study we tested the hypothesis that dietary vitamin E supplementation can improve carotid artery elasticity and cardio-vagal baroreflex gain in young, healthy individuals. A total of 20 subjects were studied in a double-blind, placebo-controlled, randomized study. Subjects in the active treatment group received 700 IU/day vitamin E for 1 month. Each subject was studied three times: before, during and 1 month after treatment. Plasma vitamin E levels were determined using high-performance liquid chromatography. Carotid artery diameter was measured by ultrasound and radial artery pressure by tonometry. Baroreflex function was assessed by time and frequency domain spontaneous indices. Plasma vitamin E levels increased by 123%, which was associated with a 20% increase in carotid artery compliance and a 30-60% increase in baroreflex indices. All these changes regressed 1 month after cessation of vitamin E supplementation. Significant correlations were observed across conditions (control, treatment and recovery), among plasma vitamin E concentrations, carotid artery compliance and distensibility values and two of the baroreflex gain indices in the treatment group. Our results demonstrate that vitamin E supplementation can increase carotid artery compliance and baroreflex gain in young, apparently healthy adults.

[Role of free radicals and reactive nitrogen species in the late complications of diabetes mellitus in rats]

In this time-course study the levels of different reactive species, especially those of nitric oxide and peroxynitrite were determined in streptozotocin-induced diabetic rat tissues at different time-points after the onset of the disease, before the development of histopathological damages. Significantly higher steady state free radical concentrations were found in the liver 3 weeks after the onset of diabetes, compared to age matched control groups. Increased nitric oxide levels in diabetic vasculature and kidney, and its rapid reaction with reactive oxygen species, resulted in high peroxynitrite generation. This suggested the onset of processes characteristic to premature aging of the endothelium. According to the histopathological results, there were no signs of late complications in the tissues up to seven weeks after induction of diabetes. In conclusion, the authors' experimental evidences support the idea of a complex role for nitric oxide, reactive oxygen species and peroxynitrite in the development of early diabetic tissue injury before the evolution of late complications. This study showed for the first time a time-course dependence for changes in nitric oxide production in diabetic tissues compared to age-matched controls at an early stage of the disease. These results suggest that oxidative stress in increased at a very early stage of diabetes and, in particular, that high levels of nitric oxide and peroxynitrite could play a decisive role in the development of late complications in the diabetic vasculature and kidney.

[Diabetes mellitus and tumors of the oral cavity--epidemiologic correlations]

INTRODUCTION AND AIMS

Numerous publications have already demonstrated that diabetes mellitus (DM) is a risk factor for the development of periodontal diseases and various inflammatory lesions in the oral mucosa. A possible correlation between DM and oral premalignancies and tumors was examined in this study, as no literature data are available concerning this problem.

METHODS

Stomato-oncological screening was carried out on 200 DM patients in the medical departments: The lesions found were classified in three groups: inflammatory lesions, benign tumors and precancerous lesions. Benign tumors were found in 14.5%, and precancerous lesions in 8% of diabetics. Earlier Hungarian screening studies indicated lower frequency of these lesions in the general population. A retrospective DM screening of 610 inpatients with histologically confirmed oral malignancies was also performed. The control group comprised 574 complaint- and tumor-free adults. Fasting blood glucose levels were determined in both groups, and the tumor location was registered in the cancer patients.

RESULTS

In the group of the oral cancer patients, DM was present in 14.6% and an elevated blood glucose level in 9.7%. These values are significantly higher than those for the tumor-free control group (p < 0.01). The gingival and labial tumor location was significantly more frequent among diabetic cancer patients than in the non-diabetic group (p < 0.01).

CONCLUSION

The combination of DM and smoking means a higher risk for oral precancerous lesions and malignancies. DM may be a risk factor for oral premalignancies and tumors.

Diabetes and oral tumors in Hungary: epidemiological correlations

OBJECTIVE

Numerous publications have already demonstrated that diabetes is a risk factor for the development of periodontal diseases and various inflammatory lesions in the oral mucosa. A possible correlation between diabetes and oral premalignancies and tumors was examined in this study, as no literature data are available concerning this problem.

RESEARCH DESIGN AND METHODS

Stomato-oncological screening was carried out on 200 diabetic patients in the medical departments; the control group included 280 adult dentistry outpatients. The lesions found were classified into three groups: inflammatory lesions, benign tumors, and precancerous lesions. A retrospective diabetes screening of 610 inpatients with histologically confirmed oral malignancies was also performed. The control group comprised 574 complaint- and tumor-free adults. Fasting blood glucose levels were determined in both groups, and the tumor location was registered in the cancer patients.

RESULTS

Benign tumors were found in 14.5% and precancerous lesions in 8% of diabetic patients. In the control group these values were significantly lower, at 6.4 and 3.2%, respectively (P>0.01). Earlier Hungarian screening studies indicated similar frequency of these lesions in the general population. The proportion of oral cavity lesions was higher among diabetic patients compared with that of the control patients. In the oral cancer patient group, diabetes was present in 14.6% and an elevated blood glucose level in 9.7%. These values are significantly higher than those for the tumor-free control group (P<0.01). The gingival and labial tumor location was significantly more frequent among diabetic cancer patients than in the nondiabetic group (P<0.01). The combination of diabetes and smoking means a higher risk for oral precancerous lesions and malignancies.

CONCLUSIONS

Diabetes may be a risk factor for oral premalignancies and tumors.

Increased nitric oxide levels as an early sign of premature aging in diabetes

The levels of different reactive species, especially those of nitric oxide and peroxynitrite, were determined in streptozotocin-induced diabetic rat tissues, before the development of histopathological damages. Significantly higher steady state free radical concentrations were found in the liver 3 weeks after the onset of diabetes compared to age-matched control groups. Increased nitric oxide levels in diabetic vasculature and kidney decreased the production of detectable reactive oxygen species. High peroxynitrite generation suggested the onset of processes characteristic to premature aging of the endothelium. According to the histopathological results, there were no signs of late complications in the tissues up to 7 weeks after induction of diabetes. These results support the idea that oxidative stress is increased at a very early stage of diabetes and, in particular, that high levels of nitric oxide and peroxynitrite could play a decisive role in the development of late complications in the diabetic vasculature and kidney.

[Stomato-oncological screening in diabetic patients]

The data of the literature suggest that studies have not been performed to date on possible correlations between diabetes and precancerous states and tumors in the oral cavity. Internationally, only one investigation appears to have dealt with the incidence of leukoplakia among diabetics. In the present work, stomato-oncological screening was performed on 200 treated diabetics. Precancerous lesions were found in 8%, and benign lesions in 14.5%. Comparison with earlier Hungarian screening studies indicated that benign and precancerous lesions occur with greater frequency among diabetics than in the average population. The proportion of oral cavity lesions is higher among diabetics of type 2 than among those of type 1. The combination of diabetes mellitus and smoking means an enhanced risk from the aspect of precancerosis of the oral cavity.

[Blood pressure volatility--a new parameter for determining blood pressure variability in type-1 diabetes mellitus]

INTRODUCTION

In diabetes the heart rate variability is decreased because of the autonomic neuropathy and parallel with this phenomenon the overnight blood pressure fall is lost. Presumably this change in the hemodynamic parameters is connected with the fact that the cardiovascular complications in type 1 diabetic patients are 2-4 times more frequent than in healthy patients. The volatility, as a new factor, is the dispersion of the proportion of the blood pressure values following each other. It exactly reflects the 24-hour blood pressure fluctuation, while the dipper/non-dipper determination differentiates only between the daytime and night-time average blood pressure values. The volatility follows the changes of the measured values in accordance to the frequency of the measurements during the whole day.

AIM

Our aim was to compare the blood pressure variability of type 1 diabetic patients (DM) and healthy controls (C).

PATIENTS AND METHODS

The authors examined 43 diabetic patients from our outpatient clinic and 45 healthy people. The blood pressures were measured with Meditech ABPM 02 monitor on workdays. The measurements started in the mornings. The frequency of the measurements was 20 minutes during the day and 50 minutes at night-time. The authors took the history of all the patients and detailed laboratory results. The patients also had ophthalmology examination, ECG and echocardiography tests.

RESULTS

During the Ambulatory Blood Pressure Monitoring we found that the systolic volatility of blood pressure values was significantly lower in DM compared to C patients. Systolic volatility: 0.133 +/- 0.011 vs. 0.175 +/- 0.014 p < 0.026. Comparing only the normotonic C and DM group systolic volatility of blood pressure values were significantly lower in DM. Systolic volatility: 0.128 +/- 0.016 vs. 0.177 +/- 0.021 p < 0.036.

CONCLUSION

It is an important new finding that in type 1 diabetic patient the volatility--a new parameter for determining blood pressure variability--is lower than in the healthy control group. At normotension state other parameters describing the blood pressure variability (like diurnal index or standard deviation) could not show this change.

Miniature ionization chamber detector developed for X-ray microprobe measurements

A windowless small ionization chamber detector has been developed for monitoring the intensity of the microbeam at the ID18F microprobe end-station of the European Synchrotron Radiation Facility. The small dimensions of the ionization chamber (10 mm along the beam direction and 5 mm perpendicular to it) make it possible to place it very close to the sample. A pinhole of diameter 50 microm was used for defining the entrance window of the ionization chamber; thus the small counter can be used as an order-selecting aperture while measuring simultaneously the intensity after the aperture. In the present work the technical characteristics, such as the current-voltage curve, stability and linearity, of the small monitor have been tested.

[Crowned dens syndrome: three new cases]

INTRODUCTION

Crowned dens syndrome is due to a microcrystalline infringement (hydroxyapatite or calcium pyrophosphate) of the retro-odontoidal ligament of atlas, often leading to the erroneous diagnosis of meningitis or spondylitis. We report on three new cases diagnosed from 1996 to 1999.

EXEGESIS

The patients complained of cervicalgies, headaches or fever. The initially evoked diagnoses were meningitis, spondylodiscitis or endocarditis. Clinical exam found meningism and an inflammatory syndrome in all patients. Analysis of the cerebro-spinal fluid realised in two cases was normal. The diagnosis of crowned dens syndrome was assessed in two cases by cervical CT scan of C1/C2. In the third case, chondrocalcinosis of a wrist allowed this diagnosis. We report a probably non fortuitous case of crowned dens syndrome associated with genetic hemochromatosis. A non steroidal anti-inflammatory treatment allowed a dramatic regression of clinical symptoms.

CONCLUSION

This entity should be better known; it can mimick numerous diagnosis and be responsible for fever in the long course.

CT densitometry of the brain: a novel method for early detection and assessment of irradiation induced brain edema

The purpose of the study was to examine if the CT densitometric analysis during radiotherapy (RT) of brain tumors is suitable for the early detection of RT induced brain edema (BE), predicting related neurological progress, and assessing the effects of different edema therapies. Planimetric CT-densitograms were constructed by modifying the "High-Lighting" method. Three theoretical density regions were defined and color-coded on the images of the brain. These were defined as edema (10-20 HU), mild edema, and normal brain (29-38 HU). Corresponding axial CT slices were created at the mid-level of the lesion and that of the periventricular white matter to verify the changes in perifocal and diffuse BE. The monitoring was performed on 50 solitary brain tumor patients treated with RT. During RT courses weekly CT-densitometric examinations were carried out. We experienced that changes in densitograms coincided with clinical symptoms, furthermore, preceded the latter. With the use of preventive edema medication based on diuretics and along with adjunctive edema medication adopted to densitograms, the 5-7 week irradiation was completed without ultimate worsening in performance state in 49 of 50 cases and besides we succeeded in avoiding the routine usage of steroids. Based on our findings the CT-densitometry is suitable for early detection and continuous assessment of BE and preventing patient distress during RT. This simple, reproducible and non-invasive procedure could provide an additional clinical tool for new treatment strategies.

[Do the interferons have an antifibrotic action? The internist's point of view]

PURPOSE

The antifibrotic action of interferon alpha on the liver is now established in hepatitis C (cf. article by T. Poynard). Numerous in vitro experimental evidences may lead people into believing in the efficacy of interferon gamma in patients with mucous membrane and pulmonary fibrosis.

CURRENT KNOWLEDGE AND KEY POINTS

A randomized study has confirmed the efficacy of interferon gamma in the idiopathic pulmonary fibrosis, probably by an anti TGF beta action. Several open studies have shown the efficacy of interferon gamma in patients with post-radiation cutaneous fibrosis (Chernobyl survivors, sequelae of radiotherapy for cancer). In systemic sclerosis, several teams have shown that interferon gamma reduced collagen synthesis by sclerodermic fibroblasts in vitro. Four open studies have also confirmed the efficacy of interferon gamma in systemic sclerosis. In our experience concerning 20 patients with diffuse systemic sclerosis, the five years survival with long term therapy was 85% and we observed an improvement in the cutaneous suppleness in 40% of these cases. There was no serious side effect.

FUTURE PROSPECTS AND PROJECTS

These encouraging results need to be confirmed by large randomized studies in pulmonary fibrosis and systemic sclerosis. Other indications should be assessed, particularly extra-cutaneous radiation sequelae and in systemic fibrosis (retroperitoneal, mediastinal and cervical).

Quantitative trace element analysis of individual fly ash particles by means of X-ray microfluorescence

A new quantification procedure was developed for the evaluation of X-ray microfluorescence (XRF) data sets obtained from individual particles, based on iterative Monte Carlo (MC) simulation. Combined with the high sensitivity of synchrotron radiation-induced XRF spectroscopy, the method was used to obtain quantitative information down to trace-level concentrations from micrometer-sized particulate matter. The detailed XRF simulation model was validated by comparison of calculated and experimental XRF spectra obtained for glass microsphere standards, resulting in uncertainties in the range of 3-10% for the calculated elemental sensitivities. The simulation model was applied for the quantitative analysis of X-ray tube and synchrotron radiation-induced scanning micro-XRF spectra of individual coal and wood fly ash particles originating from different Hungarian power plants. By measuring the same particles by both methods the major, minor, and trace element compositions of the particles were determined. The uncertainty of the MC based quantitative analysis scheme is estimated to be in the range of 5-30%.

Adrenomedullin and diabetes mellitus

Adrenomedullin (AM) is a novel 52 amino acid peptide hormone, originally isolated from human pheochromocytoma. AM acts as a local autocrine and/or paracrine vasoactive hormone and has vasodilator and blood pressure lowering properties. AM as a vasodilative molecule protects the vascular wall but its exact role is still uncertain. AM is considered to play an important endocrine role in various tissues in maintaining electrolyte and fluid homeostasis. Its plasma concentration in healthy conditions is low. In hypertension, chronic renal failure and congestive heart failure its plasma concentration increases in a parallel manner with the severity of the disease. It is assumed that this peptide plays an important role in physiological and pathological conditions compensating the effects of vasoconstrictive molecules. Investigations have proven that in diabetic angiopathies the levels and production of vasoconstrictive factors and AM are increased, while other relaxing substances such as nitric oxide (NO) are decreased. It is still uncertain whether the increased release of AM is a compensatory mechanism or a coincidental event. Although the precise role of AM in the pathogenesis of diabetic complications is still to be elucidated, the altered concentration of AM in diabetes could indicate a certain interaction between AM induction and vascular function. Hence, the induction of vascular AM can be a new target of therapeutic approach to diabetic complications.

Mild thrombocytopenia as presenting symptom of type 1 Gauchers's disease

A young woman was examined for a mild thrombocytopenia which was present for some months. No signs of bleeding had so far occurred. Physical examination was normal except for a moderately enlarged spleen. Laboratory investigations showed a low platelet count. There was no evidence of an autoimmune or hematologic disease. Bone narrow aspirate indicated Gaucher's-like cells raising the suspicion of Gaucher's disease. This was further supported by electron microscopic demonstration of Gaucher's bodies in crista biopsy specimens. However, the definitive diagnosis was obtained by verifying deficient lysosomal glucosylceramide-beta-D-glucosidase activity in peripheral blood leukocytes. Upon the absence of neurologic involvement the patient was typical for the adult-onset or type 1 form of Gaucher's disease.