Biomedical subjects

M Pavlova

Publications and source records attributed to M Pavlova.

At least 19 recordsLinked to original sources

PubMed2003

Pyramidal tract damage correlates with motor dysfunction in bilateral periventricular leukomalacia (PVL).

In children with periventricular leukomalacia (PVL), motor dysfunction is thought to be related to involvement of pyramidal tract fibres in the periventricular white matter. The purpose of the present study was to test this hypothesis. Thirteen former preterm adolescents with PVL, ten of whom were suffering from bilateral spastic cerebral palsy, were studied by MRI. The severity of pyramidal tract damage was assessed on semicoronal MRI reconstructions along anatomical landmarks of somatotopy in the precentral gyrus and the internal capsule; for comparison, the overall volume of cerebral white matter (determined by automated volumetry) served as a global measure of lesion severity. The motor dysfunction of each of the four extremities correlated much more strongly with the severity of pyramidal tract damage assessed on the respective MRI reconstruction (range of correlation coefficients, 0.647 to 0.922) than with the total volume of white matter (range of correlation coefficients, - 0.458 to - 0.212; Spearman). These findings corroborate the notion that an involvement of pyramidal tract fibres in the periventricular white matter is indeed a relevant factor for motor dysfunction in children with PVL.

Adolescent↗

PubMed2001

Self-reported hyperarousal traits among insomnia patients.

Hyperarousal Scale scores for certain self-reported behaviors reportedly correlate with EEG arousal measures. We tested whether an insomnia subject group had different Hyperarousal Scale scores compared with hypersomnia, delayed sleep phase syndrome, procrastinator or normal subject groups. Compared with 139 normal subjects, mean scores for a group of 256 insomnia subjects was significantly 1.2 S.D. higher on Hyperarousal total scale score, 0.82 S.D. higher on React subscale score and 0.85 S.D. higher on Introspectiveness subscale score. The insomnia group median Extreme score was 2.25 times that of the normal group. These self-report findings suggest that insomnia subjects may be more responsive generally. All sleep disorder groups had increased total Hyperarousal scores, although these increases were accounted for by different scale items. The procrastinator group had Hyperarousal score patterns that generally differed from those of the other groups.

Adult↗

PubMed2001

Recognition of point-light biological motion displays by young children.

We tested the ability of children 3-5 years of age to recognise biological motion displays. Children and adults were presented with moving point-light configurations depicting a walking person, four-legged animals (dogs), and a bird. Participants were able to reliably recognise displays with biological motion, but failed in the identification of a static (four consecutive frames taken from each sequence) version. The results indicate that, irrespective of the highly reduced and unusual structural information available in point-light displays, biological motion is sufficient for reliable recognition of human and non-human forms at an age as early as 3 years. Moreover, 5-year-olds exhibit the ceiling level of recognition. The findings are discussed in the context of the neuropsychological and brain mechanisms involved in biological motion perception.

Adolescent↗

PubMed2001

[Antenatal atrial tachycardia. Two case reports].

The authors report two cases of foetal supraventricular tachycardia in healthy hearts with 1/1 atrioventricular conduction which turned out to be atrial tachycardias in the postnatal period. The first foetus had permanent tachycardia at 190/minute at 34 weeks' amenorrhea with left ventricular dysfunction at 36 weeks. In the postnatal period, treatment with digoxine and amiodarone restored sinus rhythm and normal left ventricular function. Permanent foetal tachycardia, even at a rate of less than 200 beats/minute, should suggest an arrhythmia and may lead to left ventricular dysfunction in utero. The other foetus had an aneurysm of the foramen ovale with paroxysmal tachycardias at 220/minute without cardiac dysfunction. A Holter at 1 month showed paroxysmalatrial tachycardia. Postnatal rhythm monitoring is necessary in paroxysmal foetus tachycardia, especially with prenatal aneurysm of the foramen ovale.

Adult↗

PubMed2000

Appraising the financial reform in Bulgarian public health care sector: the Health Insurance Act of 1998.

The public health care services in Bulgaria were deteriorating, especially during the decade of transitional process. The method of health care finance was a major reason for the poor performance of the Bulgarian public health care sector. Bulgarian policy-makers decided that an insurance-based financial mechanism could help to rescue the failing public health care services. This paper explores the social benefits and the feasibility of the insurance-based finance in the Bulgarian public health care sector. The discussion in the paper implies that, in the current conditions of economic recession, the insurance-based health care finance can not be socially beneficial for Bulgaria. Moreover, the insurance implementation seams to be unfeasible due to a lack of sufficient financial resources.

Bulgaria↗

PubMed2000

Speed perception is affected by the Ebbinghaus-Titchener illusion.

We examined whether the apparent extent of motion affects speed perception. On the first presentation of each trial, a light dot travelled horizontally across a central circle of one of the Ebbinghaus configurations (with either small or large inducing elements). On the second presentation, observers adjusted the speed of a dot moving within the central circle alone so as to match the speed perceived in the first presentation. For all stimulus speeds (1.3, 2.1, and 5.5 deg s-1), the matched speed with small inducing circles was systematically less than that with large inducing circles. The findings indicate that the perceived speed depends on the apparent extent of motion: the larger the apparent size of a frame, the slower the apparent speed. These results are consistent with the predictions of transposition effects in visual motion.

Adolescent↗

PubMed2000

Orientation specificity in biological motion perception.

We addressed the issue of how display orientation affects the perception of biological motion. In Experiment 1, spontaneous recognition of a point-light walker improved abruptly with image-plane display rotation from inverted to upright orientation. Within a range of orientations from 180 degrees to 90 degrees, it was dramatically impeded. Using ROC analysis, we showed (Experiments 2 and 3) that despite prior familiarization with a point-light figure at all orientations, its detectability within a mask decreased with a change in orientation from upright to a range of 90 degrees-180 degrees. In Experiment 4, a priming effect in biological motion was observed only if a prime corresponded to a range of deviations from upright orientation within which the display was spontaneously recognizable. The findings indicate that display orientation nonmonotonically affects the perception of biological motion. Moreover, top-down influence on the perception of biological motion is limited by display orientation.

Adolescent↗

PubMed2000

Primacy and frequency effects in absolute judgments of visual velocity.

In absolute judgment tasks, identical stimuli are rated higher (or lower) when presented in a series of more frequent small (or large) stimuli. Using visual stimuli differing in velocity, we show that this conventional frequency effect is largely modulated by the primacy effect--that is, by the stimuli occurring on the early trials of a run. In Experiment 1, a frequency-like primacy effect was obtained with equal-frequent velocities. Identical velocities were rated faster when mainly slow rather than fast ones occurred on initial trials. In Experiment 2, we contrasted the frequency effect and the primacy effect: In runs with frequent slow velocities, mainly fast ones occurred earlier, whereas in runs with infrequent slow velocities, mainly slow ones did so. Lack of differences of ratings in the two conditions suggests that the two effects canceled each other. In Experiment 3, when mainly frequent velocities occurred earlier, the conventional frequency effect was obtained. We conclude that the conventional frequency effect represents a combination of the primacy effect and the pure frequency effect.

Acceleration↗

PubMed1999

Gamma-band MEG activity to coherent motion depends on task-driven attention.

We examined gamma-band magnetoencephalographic (MEG) activity in humans manipulating attention to visual stimuli by auditory distractors. After exposure to both visual and auditory noise (a baseline), subjects attended to the first of two stimuli (either regular motion of bars or a tone sequence) presented asynchronously, and responded to its offset. A spectral power analysis revealed an increased, relative to baseline, 40 Hz MEG response to attended coherent motion. The enhancement occurred within the initial 50-250 ms from motion onset over modality-specific (occipital) cortices. The increase was not observed when attention was captured by auditory distractors. Our findings suggest that 40 Hz activity in the human visual cortex is related to integration of featural information that is supported by attention.

Acoustic Stimulation↗

PubMed1999

Notochord-dependent expression of MFH1 and PAX1 cooperates to maintain the proliferation of sclerotome cells during the vertebral column development.

During axial skeleton development, the notochord is essential for the induction of the sclerotome and for the subsequent differentiation of cartilage forming the vertebral bodies and intervertebral discs. These functions are mainly mediated by the diffusible signaling molecule Sonic hedgehog. The products of the paired-box-containing Pax1 and the mesenchyme forkhead-1 (Mfh1) genes are expressed in the developing sclerotome and are essential for the normal development of the vertebral column. Here, we demonstrate that Mfh1 like Pax1 expression is dependent on Sonic hedgehog signals from the notochord, and Mfh1 and Pax1 act synergistically to generate the vertebral column. In Mfh1/Pax1 double mutants, dorsomedial structures of the vertebrae are missing, resulting in extreme spina bifida accompanied by subcutaneous myelomeningocoele, and the vertebral bodies and intervertebral discs are missing. The morphological defects in Mfh1/Pax1 double mutants strongly correlate with the reduction of the mitotic rate of sclerotome cells. Thus, both the Mfh1 and the Pax1 gene products cooperate to mediate Sonic hedgehog-dependent proliferation of sclerotome cells.

Animals↗

PubMed1998

Factors affecting the prognosis of Ebstein's anomaly during fetal life.

BACKGROUND: The echocardiographic criteria that have been used to evaluate severity of Ebstein's anomaly in utero are the same as those applied after birth. OBJECTIVE: The objective of this study was to establish prognostic criteria that take into account the peculiarities of the fetal hemodynamics. METHOD: The video recordings of eight fetuses with Ebstein's anomaly were retrospectively reviewed. RESULTS: The following indexes had no prognostic significance either on fetal or neonatal outcome: the ratio of functional tricuspid opening over the diameter of the annulus, the degree of displacement of the tricuspid valve opening, and the degree of tricuspid regurgitation. The index of severity (based on the surfaces of right atrium + atrialized right ventricle) and the cardiothoracic ratio had a significant impact only on neonatal survival. The smallest fossa ovalis were found in two fetuses who had hydrops. Fetuses who reached term without problems had higher left ventricular outputs. A positive linear correlation was found between the z score of the left ventricular output and the size of the fossa ovalis (r = 0.81, p < 0.05). CONCLUSION: The prognosis of Ebstein's anomaly during fetal life is not influenced by criteria described for postnatal life and may be related to factors that control the volume load of the left ventricle.

Ebstein Anomaly↗

PubMed1998

An assessment of the exposure of technicians working in a chemical laboratory for aromatic hydrocarbons at Neftochim, Burgas.

The average exposure to aromatic hydrocarbons per working shift of laboratory assistants at a chemical laboratory were measured. The laboratory is one of the service departments for four different production departments at Neftochim, Burgas--the largest oil refinery in Bulgaria. Long-term sampling of the air from different workplaces in the laboratory was performed by sampling charcoal sorbent tubes (type CT-CN-2), manufactured by Higitest (type NIOSH). The concentration of benzene, toluene, ethyl benzene, xylene and isopropyl benzene in the air at the laboratory was determined by gas chromatography using the Varian MEGA 1 with a flame ionisation detector and Inowax capillary column. The measured exposure levels of toxic substances in the aromatic hydrocarbons analysis laboratory were as follows: Benzene, 0.15-1.3 mg/m3, in single samples its concentration was 4.06-8.63 mg/m3; toluene, 0.15-0.46 mg/m3, in single samples its concentration was 5.5-15.62 mg/m3; ethyl benzene in most samples was 0.02 mg/ m3, in single samples its concentration was 20.68 mg/m3; xylene in most samples was 0.4 mg/m3, in single samples its concentration was 0.51-1.68 mg/m3; isopropyl benzene in most samples was 0.1 mg/m3, in single samples its concentration was 0.20-1.12 mg/m3. The results, obtained by measuring the average work-shift exposure of laboratory assistants to aromatic hydrocarbons in the air at the analytical laboratories, show that the measured concentrations are smaller than the respective threshold limit values. Bearing in mind, however, that some of these substances have an effect on the human organism, exposure to them is excessively hazardous for laboratory technicians.

Bulgaria↗

PubMed1997

Therapeutic efficacy of "Milgamma" in patients with painful diabetic neuropathy.

Forty-five diabetes patients with painful peripheral polyneuropathy were enrolled in a 3-month observational study comparing the therapeutic efficacy of Milgamma tablets (50 mg benfothiamine and 0.25 mg cyancobalamine) with parallel randomized treatment assignment with the conventional vitamin B complex treatment regimen Neurobex. Thirty patients in group one were randomized to receive two Milgamma tablets qid for three weeks followed by 1 Milgamma tablet tid for 9 weeks. In group two 15 patients received two Neurobex tablets tid for the entire 3-month study period. Therapeutic efficacy was assessed on the basis of within-patient differences in pain severity between Milgamma and Neurobex-treated patients and in vibration perception thresholds using the Rydel-Seiffer biothesiometer at baseline and at the end of the study. Statistically significant relief of both background and peak neuropathic pain was achieved in all of the Milgamma-treated patients and vibration perception thresholds dramatically improved with a median of 1.56 measured on the biothesiometer scale (t = 3.24, P < 0.01). The sensory symptoms improvement was insignificant in the Neurobex-treated patient group and the changes in the vibration perception thresholds failed to reach statistical significance. The therapeutic efficacy of Milgamma was greater in patients with early-stage diabetes as compared with those with advanced diabetic neuropathy. No adverse reactions were observed following the administration of the medication. Our results underscore the importance of Milgamma tablets as an indispensable element in the therapeutic regimen of patients with painful diabetic polyneuropathy.

Adult↗

PubMed1997

Percutaneous ethanol sclerotherapy of autonomous thyroid nodules: preliminary results.

Percutaneous ethanol sclerotherapy was applied to 20 patients (17 women and 3 men, aged 30 to 77 yrs) with autonomous thyroid nodules. The patients either were contraindicated because of hazardous concomitant diseases or refused surgical or 131I treatment. Ethanol (95 alc%) was injected in 4 to 6 sessions at a mean dose of 0.63 ml/cc nodular tissue. Physical examination, T3, T4 and TSH assays, thyroid scintigraphy, sonography, and fine needle aspiration biopsy were used to evaluate the treatment results within a 12-month follow-up. Two months after ethanol injection all patients showed an improvement; in six patients the symptoms recurred in the 6th month. Two of them underwent a second cycle of ethanol injection. 12 months later an euthyroid state was maintained in 16 (80%) patients, while 4 (20%) did not respond to the treatment. The treatment results were markedly determined by the nodule size as no effect was achieved in nodules larger than 15-20 ml in volume. This method appears to be an appropriate and harmless alternative to the surgical and 131I treatment of autonomous thyroid nodules less than 15-20 ml in volume, especially in patients with grave concomitant diseases.

Adult↗

PubMed1996

[Importance of intrauterine diagnosis of rudimentary autonomic circulation in an acardiac twin].

Foetal acardia is a major complication of twin pregnancies which endangers the life of the healthy twin. The authors report the case of a twin pregnancy with an acardiac twin followed up by repeated echocardiography from the 20th week of pregnancy until delivery at the 36th week. Despite the presence of a parasitic mass, the healthy twin showed no sign of heart failure. Attentive ultrasonography of this mass showed a certain degree of autonomic circulation ensured by a rudimentary cardiac pump. This case confirms the favorable effect of this finding on the healthy twin, moreover, it clarifies some haemodynamic features of the parasitic mass: to-and-fro circulation, characteristic of a cardiac pump without a valve, anastomoses and competitive flow between the two circulatory systems.

Abnormalities, Multiple↗

PubMed1995

Treatment of delayed sleep phase syndrome.

Delayed sleep phase syndrome (DSPS) is a common but little reported cause of severe insomnia. Affected individuals complain of difficulty falling asleep and difficulty awaking at socially acceptable hours. It results from a dysregulation of the circadian sleep-wake cycle. DSPS presents in clinically heterogenous ways as modulated by motivation, psychopathology, drug status, and treatment compliance factors. Patients respond variably to the range of possible treatments. Bright light treatment potentially corrects the circadian abnormality of DSPS. Other treatments reported to relieve some DSPS patients include schedule shifts, drugs, and vitamin and hormone treatments. The safety and efficacy of light treatment have not been conventionally defined, but available information suggests that it is ophthalmologically safe. At present, DSPS must be managed empirically by various methods.

Adolescent↗

PubMed1994

Structure of the Drosophila HeT-A transposon: a retrotransposon-like element forming telomeres.

Telomeres of Drosophila appear to be very different from those of other organisms. A transposable element, HeT-A, plays a major role in forming telomeres and may be the sole structural element, since telomerase-generated repeats are not found. HeT-A transposes only to chromosome ends. It appears to be a retrotransposon but has novel structural features, which may be related to its telomere functions. A consensus sequence from cloned HeT-A elements defines an element of approximately 6 kb. The coding region has retrotransposon-like overlapping open reading frames (ORFs) with a -1 frameshift in a sequence resembling the frameshift region of the mammalian HIV-1 retrovirus. Both the HeT-A ORFs contain motifs suggesting RNA binding. HeT-A-specific features include a long non-coding region, 3' of the ORFs, which makes up about half of the element. This region has a regular array of imperfect sequence repeats and ends with oligo(A), marking the end of the element and suggesting a polyadenylated RNA transposition intermediate. This 3' repeat region may have a structural role in heterochromatin. The most distal part of each complete HeT-A on the chromosome, the region 5' of the ORFs, has unusual conserved features, which might produce a terminal structure for the chromosome.

Amino Acid Sequence↗

PubMed1994

Hydrolytic stability of polyurethane medical adhesive dressings.

The present study deals with the effect of the type and chemical character of incorporated polyester (polyether blocks) on the hydrolytic stability of different types of polyurethane medical adhesive dressings. Diffusion parameters of the investigated polyurethane adhesives, giving information concerning the chemical changes taking place in water or physiological solution, have also been determined.

Adhesives↗