Ultracytochemical Localization of Calcium in the Superficial Pineal Gland of the Mongolian Gerbil

In order to demonstrate fine localization of Ca2+ in the superficial pineal gland of Meriones unguiculatus, the pyroantimonate technique was employed. Control experiments were performed with EGTA and analysis of obtained reaction product using an energy-dispersive x-ray microanalysis. Precipitates of calcium antimonate were formed almost exclusively in swollen clear pinealocytes, in and along their cell membranes, over their nuclei, in mitochondria, the Golgi apparatus, endoplasmic and integrade reticulums, acervuli, in vesicles surrounding synaptic bars, cytoplasmic matrix, and flocculent extracellular material. It has been concluded that the swollen pinealocytes represent a degenerative cell form probably occurring by impairment of plasmalemmal Ca2+-ATPase's ability to eliminate Ca2+ ion from the cell, with consecutive increase of calcium in the cytoplasmic matrix, followed by increase of intramitochondrial Ca2+ concentration, gradual arrest of mitochondrial function, depolymerization of cytoskeletal microtubuli, loss of the cell form, and cell death. Decrease of function of pinealocyte plasmalemma seems to be related to aging.     

Levofloxacin can be used effectively as a positive control in thorough QT/QTc studies in healthy volunteers

AIMS

To characterize the effects of levofloxacin on QT interval in healthy subjects and the most appropriate oral positive control treatments for International Conference on Harmonization (ICH) E14 QT/QTc studies.

METHODS

Healthy subjects received a single dose of levofloxacin (1000 or 1500 mg), moxifloxacin (400 mg) or placebo in a four-period crossover design. Digital 12-lead ECGs were recorded in triplicate. Measurement of QT interval was performed automatically with subsequent manual onscreen over-reading using electronic callipers. Blood samples were taken for determination of levofloxacin and moxifloxacin concentrations.

RESULTS

Mean QTcI (QT interval corrected for heart rate using a correction factor that is applicable to each individual) was prolonged in subjects receiving moxifloxacin 400 mg compared with placebo. The largest time-matched difference in QTcI for moxifloxacin compared with placebo was observed to be 13.19 ms (95% confidence interval 11.21, 15.17) at 3.5 h post dose. Prolonged mean QTcI was also observed in subjects receiving levofloxacin 1000 mg and 1500 mg compared with placebo. The largest time-matched difference in QTcI compared with placebo was observed at 3.5 h post dose for both 1000 mg and 1500 mg of levofloxacin [mean (95%) 4.42 ms (2.44, 6.39) in 1000 mg and 7.44 ms (5.47, 9.42) in 1500 mg]. A small increase in heart rate was observed with levofloxacin during the course of the study. However, moxifloxacin showed a greater increase compared with levofloxacin.

CONCLUSIONS

Both levofloxacin and moxifloxacin can fulfil the criteria for a positive comparator. The ICH E14 guidelines recommend a threshold of around 5 ms for a positive QT/QTc study. The largest time-matched difference in QTc for levofloxacin suggests the potential for use in more rigorous QT/QTc studies. This study has demonstrated the utility of levofloxacin on the assay in measuring mean QTc changes around 5 ms.     

Degree of genetic homozygosity and distribution of AB0 blood types among patients with spina bifida occulta and spina bifida aperta

Introduction

Assuming that spina bifida (SB) is a genetically controlled disease, the aim of our study was to evaluate the degree of genetic homozygosity and the distribution of AB0 blood types among patients with SB occulta and SB aperta by the homozygously recessive characteristics (HRC) test.

Material and methods

Our study included an analysis of the presence, distribution and individual combination of 15 selected genetically controlled morpho-physiological traits in a sample of 100 patients with SB (SB occulta N = 50 and SB aperta N = 50) and a control group of individuals (N = 100).

Results

We found a statistically significant difference between the mean values for genetic homozygosity (SB 4.5 ±0.3; control 3.0 ±0.2, p < 0.001) and also differences in the presence of certain individual combinations of such traits. In 12 (80.0%) of the 15 observed characteristics, recessive homozygosity was expressed to a greater degree among the group of SB patients, while for 9 (60.0%) of the traits this level of difference was statistically significant (Σ_χ ² = 266.3, p < 0.001). There was no difference in average homozygosity of such genetic markers between groups of SB occulta and SB aperta patients, but the type of individual variation in the two studied groups significantly differed. In the group of patients with SB the frequency of 0 blood group was significantly increased while B blood group was significantly decreased.

Conclusions

Our results clearly show that there is a populational genetic difference in the degree of genetic homozygosity and variability between the group of patients with SB and individuals without clinical manifestations, indicating a possible genetic component in the aetiopathogenesis of spina bifida.     

Distribution of affected muscles and degree of neurogenic lesion in patients with spina bifida

Introduction

Patients with spina bifida in the lumbosacral region usually have various degrees of motor and sensory dysfunctions of the lower extremities and anal sphincter. The aim of our study was to evaluate the distribution and differences in frequencies of affected muscles, number of affected muscles and degree of neurogenic lesion between patients with spina bifida occulta (SBO) and spina bifida aperta (SBA).

Material and methods

In 100 patients with SB, 6 muscles in the lower limbs were separately analysed. Due to the number of affected muscles, we evaluated 5 groups of patients: with 1 affected muscle, 2 affected muscles, 3 affected muscles, 4 affected muscles and 5 affected muscles. Three degrees of neurogenic lesions were assessed: mild, moderate and severe.

Results

The tibialis anterior muscle was most frequently affected in SB patients. The outer anal sphincter was frequently affected in the group of SBA patients. Single muscle affection is frequent in the group of patients with SBO, while in the group of patients with SBA, 4 muscles were significantly frequently affected. The great majority of patients (45.46%) with affected outer anal sphincter (OAS) in the group of SBO were without affection of other muscles, while for the SBA group it was for every third patient. Mild neurogenic lesion was significantly frequent in SBO patients, while severe form was significantly frequent in SBA patients.

Conclusions

Patients with SBO usually present with mild to moderate clinical presentation, while multiple root involvement and severe degree of neurogenic lesion is associated more frequently with SBA.     

Die Einwirkung von K?lte auf mit Zinkjodid-Osmium tetroxyd reagierende synaptische Bl?schen in den Nervenendigungen im Corpus pineale der Ratte

Zusammenfassung In den synaptischen Bläschen der Nervenendigungen der Epiphyse von Ratten, welche 2 und 4 Tage einer Temperatur von –6° bis –8°C ausgesetzt worden waren, hat man eine signifikante Vermehrung des Zinkjodid-Osmiumtetroxyd (ZIO) reaktiven Materials festgestellt. Der durchschnittliche Durchmesser der ZIO-positiven synaptischen Vesiculae betrug bei den Kontrollratten 234 Å und bei den Ratten, welche 2 und 4 Tage unter der Kälte gelebt hatten, 380 Å, bzw. 379 Å. Die ZIO-Reaktion war bei den Kontrollratten in 49,3% der synaptischen Vesiculae positiv, nach zweitägiger Kälteeinwirkung waren 58,7% und nach viertägiger Kälteeinwirkung 72,1% der synaptischen Vesiculae ZIO-positiv. Auf Grund der vorliegenden Arbeit war es jedoch nicht möglich zu entscheiden, ob die Vermehrung des ZIO-reaktiven Materials mit einer gleichzeitigen Zunahme der biogenen Amine verbunden ist.

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The influence of cold on zinc iodide-osmium tetroxide reactive synaptic vesicles in the pineal nerve endings of the rat

Summary In the synaptic vesicles of pineal nerve endings of Wistar rats exposed for 2 and 4 days to a temperature of –6° to –8° C, a significant increase of the zinc iodide-osmium tetroxide (ZIO) reactive material was observed. The mean diameter of ZIO reactive synaptic vesicles of control rats was 234 Å; in rats exposed to cold for 2 and 4 days it was 380 Å, respectively 379 Å. In control rats the ZIO reaction was positive in 49,3% of the synaptic vesicles. The reactivity increased to 58,7% in rats exposed to cold for 2 days, and to 72,1% in rats exposed to cold for 4 days. However, the results of the present study do not permit to conclude if an increase of ZIO reactive material is accompanied by a simultaneuos increase of biogenic amines.

     

Comparison of Six Commonly Used QT Correction Models and Their Parameter Estimation Methods

This paper compares six commonly used QT correction models and three available parameter estimation methods using five indices for QTc evaluation based on real and simulated electrocardiograph (ECG) datasets. The results show that the golden section approach always finds the correction factor making QTc interval uncorrelated to heart rate for all six formulas. However, the correction formulas derived from mixed model sometimes fail to make QTc interval invariant of heart rate. The performance of an individual least-square regression method lies between the golden section iteration approach and the mixed model in terms of QTc–RR relationship.     

Susceptibility to oxidative stress, insulin resistance, and insulin secretory response in the development of diabetes from obesity

BACKGROUND/AIM: [corrected] Oxidative stress plays a critical role in the pathogenesis of various diseases. Recent reports indicate that obesity may induce systemic oxidative stress. The aim of the study was to potentiate oxidative stress as a factor which may aggravate peripheral insulin sensitivity and insulinsecretory response in obesity in this way to potentiate development of diabetes. The aim of the study was also to establish whether insulin-secretory response after glucagonstimulated insulin secretion is susceptible to prooxidant/antioxidant homeostasis status, as well as to determine the extent of these changes. METHODS: A mathematical model of glucose/insulin interactions and C-peptide was used to indicate the degree of insulin resistance and to assess their possible relationship with altered antioxidant/prooxidant homeostasis. The study included 24 obese healthy and 16 obese newly diagnozed non-insulin dependent diabetic patients (NIDDM) as well as 20 control healthy subjects, matched in age. RESULTS: Total plasma antioxidative capacity, erythrocyte and plasma reduced glutathione level were significantly decreased in obese diabetic patients, but also in obese healthy subjects, compared to the values in controls. The plasma lipid peroxidation products and protein carbonyl groups were significantly higher in obese diabetics, more than in obese healthy subjects, compared to the control healthy subjects. The increase of erythrocyte lipid peroxidation at basal state was shown to be more pronounced in obese daibetics, but the apparent difference was obtained in both the obese healthy subjects and obese diabetics, compared to the control values, after exposing of erythrocytes to oxidative stress induced by H2O2. Positive correlation was found between the malondialdehyde (MDA) level and index of insulin sensitivity (FIRI). CONCLUSION: Increased oxidative stress together with the decreased antioxidative defence seems to contribute to decreased insulin sensitivity and impaired insulin secretory response in obese diabetics, and may be hypothesized to favour the development of diabetes during obesity.