Phase synchronization measurements using electroencephalographic recordings: what can we really say about neuronal synchrony?

Phase synchrony analysis is a relatively new concept that is being increasingly used on neurophysiological data obtained through different methodologies. It is currently believed that phase synchrony is an important signature of information binding between distant sites of the brain, especially during cognitive tasks. Electroencephalographic (EEG) recordings are the most widely used recording technique for recording brain signals and assessing phase synchrony patterns. In this study, we address the suitability of phase synchrony analysis in EEG recordings. Using geometrical arguments and numerical examples, employing EEG and magnetoencephalographic data, we show that the presence of a common reference signal in the case of EEG recordings results in a distortion of the synchrony values observed, in that the amplitudes of the signals influence the synchrony measured, and in general destroys the intended physical interpretation of phase synchrony.     

Insulin sensitivity, insulin secretion and beta-cell function during puberty in overweight Hispanic children with a family history of type 2 diabetes

OBJECTIVE: To examine cross-sectional differences in insulin sensitivity, insulin secretion and beta-cell function during puberty in overweight Hispanic boys and girls with a family history of type 2 diabetes. STUDY DESIGN AND PARTICIPANTS: This cross-sectional, observational study included 214 8-13-y-old Hispanic children with a BMI percentile > or = 85th percentile and family history of type 2 diabetes. METHODS AND ANALYSES: Participants underwent a physical examination, body composition measures, oral glucose tolerance test (OGTT), and frequently-sampled intravenous glucose tolerance test. Unadjusted and adjusted general linear models (GLM) tested whether insulin/glucose dynamics differed by Tanner stage and gender. RESULTS: Unadjusted group comparisons showed that fasting insulin increased whereas insulin sensitivity (SI) and the disposition index (DI) (a measure of pancreatic beta-cell function) decreased across Tanner stage groups (all P < 0.05). No differences in the acute insulin response to glucose (AIRg), fasting glucose or 2-h glucose were found. After adjusting for covariates, there was no independent effect of Tanner stage on SI (P = 0.9) or AIRg (P = 0.2), but DI was slightly lower in later Tanner stages suggesting decreased beta-cell function in the more mature groups (P = 0.10). CONCLUSIONS: Overweight Hispanic children with a family history of type 2 diabetes may represent a unique population given that pubertal insulin resistance was not evident once analyses controlled for body composition. Longitudinal analyses are required to determine whether the slightly diminished beta-cell function in later Tanner stages plays a role in the development of type 2 diabetes.     

The results of the treatment of right ventricle myocardial infarction

AIM: To present the results and experience in diagnosing and treating of patients with acute right ventricle infarction, during the period of hospitalization of one month, with adjuvant analyses of the obtained results in the period of fifteen years. METHODS: Acute right ventricle infarction porved clinicaly, enzymologicaly, by ECG, echochardiographically or scintigraphically we treated with thrombolitic therapy within first six hours after admittion, with salvaged PTA in case of the cardiogenic shock or AV block II degrees-III degrees despite of thrommbolitic therapy, or with postponed PTA within first month of intrahospital treatment. RESULTS: In the period from 1990 to 2004, 3 225 patients of both sexes were treated for acute myocardial infarction at the different localization in patients' at the mean age of 53.7 +/- 5.8. One-hundred-thirty-nine (43.9%) patients were treated with thrombolitic therapy according to the speed up protocole. Heparin was administered to 160 (50.7%) patients with water load, and 17 (5.4%) patients had the primary percutaneous transluminal coronary angioplasty (PPTCA), so that the mechanical blood flow could be established, by the implantation of a stent when necessary. In 316 patients with right ventricle infarction, 58 (18.3%) had postponed and salvaged percutaneous transluminal coronary angioplasty (PTCA). Twenty-two (15.8%) patients had thrombolitic therapy, whereas 36 (22.5%) patients were treated with heparin. We had a successful balloon dilatation in 21 (36.2%), whereas 32 (55.2%) patients had 1-3 intracoronary stents inplanted, depending upon the necessity, and 5 (8.6%) patients from this group were sent to surgical intervention. In the group of 214 (67.7%) patients treated with heparin or thrombolitic therapy combined therapy, with PTCA, 12 (5.7%) patients died, whereas in the group of 124 (39.3%) patients treated only with heparin 26 (16.2%) patients died, statistically significant difference (p < 0.001, chi2 = 18.423). Was noticed n the group of 1 204 patients with inferoposterior infarction, 122 (10.1%) patients died. In the group of 316 patients with right ventricle infarction, 38 (12%) died. In the group of 888 control patients with inferoposterior infarction, but without right ventricle infarction, 84 (9.4%) patients died. In the group of 2 021 patients (62.2%) with anterior infarction, 248 (12.3%) died. CONCLUSION. The obtained results showed that the patients with right ventricle infarction, due to the great expansion of necrosis and the involvement of the inferoposterior wall of the left ventricle, as well as the ischemia of sinus and AV nodes, were the patients of a high risk. That was why it was essential to do urgent widening of the artery to reestablish blood flow either by using drugs or by means of mechanical methods.     

Acute leg compartment syndrome after exertion

A case of a 22-year old soldier, with a history of pain in the leg during heavy exercise, which desisted at rest, was presented. One day before admission, the patient had felt an extreme exertion-induced pain in his right leg which had not lessenned at rest. At the same time, the patient noticed persistent severe leg edema. On physical examination, the intracompartmental pressure was 62 mmHg (> 30 mmHg). The patient was urgently operated on, and fasciotomy according to Mubarak was used. At second surgery, the debridement of the muscles of the posterior group of the leg, and the evacuation of hemathoma from the anterior and lateral group of the right leg muscles were perfomed. Postoperative recovery was uneventful. Fasciotomy wounds were closed within 14 days of the surgery. The complete physical treatment was done. Follow-up examinations 1, 3, and 6 months afterwards were satisfactory. The soldier completed his compulsory military service without any sequelae. Laboratory results were normal. Overlooked, unrecognized or surgically untreated compartment syndrome can cause severe damage, including even the loss of the extremity.     

Quantitative analysis of the nephron during human fetal kidney development

BACKGROUND: The development of human kidney is a complex process. The number, shape, size, and distribution of nephrons as functional units in a kidney, provide some important information about the organization of the kidney. The aim of this study was to extend the knowledge of the developing human kidney by studying nephrons in the kidney's cortex during gestation. METHODS: Kidney tissue specimens of 32 human fetuses, the gestational age from IV lunar month (LM IV) to LM X, were analysed. Specimens were divided in ten groups based on gestational age. Stereological methods were used at the light microscopic level to estimate the volume densities of the corpuscular and tubular components of the nephron in the cortex of the developing human kidney. RESULTS: Nephron polymorphism was the main characteristic of the human fetal kidney during development. In younger fetuses, just below the renal capsule, there was a wide nephrogenic zone. It contained the condensed mesenchyme and terminal ends of the ureteric bud. Nephrons, in the different stages of development, were located around the ureteric bud which branched in the cortical nephrogenic zone and induced nephrogenesis. More mature nephrons were located in the deeper part of the cortex, close to the juxta-medullary junction. During gestation, nephrogenesis continually advanced, and the number of nephrons increased. Glomeruli changed their size and shape, while the tubules changed their length and convolution. Renal cortex became wider and contained the more mature glomeruli and the more convoluted tubules. The volume density of the tubular component of the nephron increased continually from 10.53% (LM IVa) to 27.7% (LM X). Renal corpuscles changed their volume density irregularly during gestation, increasing from 13% (LM IVa) to 15.5% (LM IVb). During the increase of gestational age, the volume density of corpuscular component of the nephron decreased to 11.7% (LM VIII), then went on increasing until the end of the intrauterine development (LM X) when corpuscles occupied 16.73% of the cortical volume. The volume density of the developing nephrons (corpuscular and tubular portion) showed the significant positive correlation (r = 0.85; p<0.01) with gestational age. CONCLUSION: The present study was one of few quantitative studies of the human developing nephron. Knowledge about the normal development of the human kidney should be important for the future medical practice.     

The aqueous humour antioxidative capacity in different types and color of the age-related cataract

BACKGROUND/AIM: Oxidative stress results from increased oxidative processes, decreased antioxidative protection, or both processes simultaneously. Photooxidative stress, as a form of oxidative stress, induced by the energy of solar radiation, today is considered as crucial in the age-related cataractogenesis. Other known and unknown, endogenous and egsogenous factors that contribute to the oxidative stress intensity, can influnce the cataract type and brunescence. Thus the oxidative stress intensity and its form might determine the cataract type and brunescence, and also make the efforts in cataract prevention more complex. Hence, the objective of the present paper was to investigate the current amount of antioxidative capacity in aqueous humour during the cataract genesis of different types and pigmentation of cataract. METHODS: Transversal review of 80 samples of humour aqueous obtained during extracapsular cataract extraction. Aqueouses were analyzed by tiobarbituric acid (TBA) method for the total antioxidant activity estimation, expressed as %iMDA, and by using 0.1 ml of aqueous. RESULTS: The mixed type of cataract showed the statistically significantly lower values of the intensities of antioxidative protection in aqueous humour compared to cortical and nuclear cataracts (p < 0.001, respectively). Between pure nuclear and cortical cataracts we found the small differences of the investigated parameter, but they pointed to the decreased level of antioxidative protection, i.e. the increased intensity of the aqueous humour oxidative stress in the cortical cataract type. A significant correlation betweer the cortical cataract maturation and the %iMDA (p < 0.05) was found. CONCLUSIONS: The role of the oxidative stress, here expressed as the antioxidative capacity of aqueous humour, could not be the same for all the cataract types. The lower level of antioxidative protection of aqueous in brunescent and mixed cataracts may point to the higher intensity of oxidative stress in those cataract types. The correlation betweer the cortical cataract maturity and %iMDA points to the significant decrease of the aqueous antioxidative protection in the cataract progression.     

Increased apoptosis and inflammation after focal brain ischemia in mice lacking connexin43 in astrocytes

Astrocytes secrete cytokines and neurotrophic factors to neurons, consistent with a neurosupportive role for astrocytes. However, in ischemic or metabolic insults, the function of astrocytic gap junctions composed mainly from connexin43 (Cx43) remains controversial. We have previously shown that heterozygous Cx43 null mice subjected to middle cerebral artery occlusion exhibited significantly enhanced stroke volume and apoptosis compared to wild-type mice. In this study, we used mice in which the human GFAP promoter-driven cre transgene deletes the floxed Cx43 gene in astrocytes, excluding the effects from reduced Cx43 expression in many other cell types as well as astrocytes. We induced focal brain ischemia in mice lacking Cx43 in astrocytes [Cre(+)] and control littermates [Cre(-)]. Cre(+) mice showed a significantly increased stroke volume and enhanced apoptosis, detected by terminal dUTP nick-end labeling and caspase-3 immunostaining, compared to Cre(-) mice. Inflammatory response assessed by the microglial marker CD11b was amplified in the penumbra of Cre(+) mice compared to that of Cre(-) mice. Our results suggest that astrocytic gap junctions could be important for the regulation of neuronal apoptosis and the inflammatory response after stroke. These findings support the view that astrocytes play a critical role in neuroprotection during ischemic insults.