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Biomedical subjects

M Petrova

Publications and source records attributed to M Petrova.

At least 19 recordsLinked to original sources
PubMed2001

Mercury resistance transposons of gram-negative environmental bacteria and their classification.

A total of 29 mercury resistance transposons were isolated from mercury-resistant environmental strains of proteobacteria collected in different parts of Eurasia and the USA and tested for hybridization with probes specific for transposase genes of known mercury resistance transposons. 9 were related to Tn21 in this test, 12 were related to Tn5053, 4 to Tn5041 and 1 to Tn5044; three transposons were negative in this test. Restriction mapping and DNA sequencing revealed that 12 transposons were identical or nearly identical to their corresponding relatives while the rest showed varying divergence from their closest relatives. Most of these previously unknown transposons apparently arose as a result of homologous or site-specific recombination. One of these, Tn5046, was completely sequenced, and shown to be a chimera with the mer operon and the transposition module derived from the transposons related to Tn5041 and to Tn5044, respectively. Transposon Tn5070, showing no hybridization with the specific probes used in this study, was also completely sequenced. The transposition module of Tn5070 was most closely related to that of Tn3 while the mer operon was most closely related to that of plasmid pMERPH. The merR of Tn5070 is transcribed in the same direction as the mer structural genes, which is typical for mer operons of gram-positive bacteria. Our data suggest that environmental bacteria may harbor many not yet recognized mercury resistance transposons and warrant their further inventory.

Bacterial Proteins↗
PubMed1998

Incidence of dental caries /Is/ on milk molars /M1,M2/ in 3-8 year-old children from Plovdiv.

The incidence of dental caries /Is/ on deciduous molars in 1216 children aged 3 to 8 from Plovdiv has been studied. The results showed highest Is in the fissures of m1 and m2 and lowest Is on the smooth surfaces. The incidence of dental caries is getting higher with statistically significant differences in the lower jaw up to the 6th year and in the upper jaw up to 7th year of age. Is in the lower jaw is higher than that of the upper jaw only in the fissures.

Bulgaria↗
PubMed1998

Dimensions of hard dental tissues and pulp cavity of the crown in first mandibular molar measured with computerized tomography.

In spite of the numerous studies (carried out by different authors and with various methods) to determine the dimensions of teeth, the size of the enamel and the dentin in different topographic regions of the tooth crown have not yet been established. The present study aimed at developing a mathematical model of the first mandibular molar by measuring the thickness of its enamel, dentin and pulp cavity. The study was conducted upon 15 first mandibular molars in 18-year-old high-school students with intact dentition using computerized tomography (SY-3000). The hard dental tissues dimensions in different topographic regions of first mandibular molar were determined by densoprofile measuring of four 1-mm-wide sections oriented in relation to the frontal plane and axis of the tooth. The obtained data are presented in a tabular form. The basic values for the crown height, the mediodistal and vestibulo-oral dimensions do not differ significantly from the values that are currently widely-known in the literature. The thickness of the enamel and dentin in different topographic regions are determined in details, which gives a clear picture of the safety zones location around the pulp cavity. On the basis of the obtained results it is possible to develop a mathematical model of the first mandibular molar.

Adolescent↗
PubMed1998

Topographic distribution of occlusal contacts of the first mandibular molar--comparative study.

The specification of the occlusal contacts in the posterior teeth region is a necessary clinical reference point for creating optimal interrelations between the teeth and dentition. The methods, such as the photo-occlusal method, the quasiplanimetric method, two-phase proof imprint in central occlusion, recording of contacts with profile wax, that have been used in studying the number and location of occlusal contacts at various positions of the mandible in relation to the maxilla are exact but difficult to apply clinically. The purpose of the present study is to find the topographic distribution of occlusal contacts in intact first mandibular molars using a method that is easy to utilise clinically and to compare the present results with the findings of the authors. The masticatory teeth of 100 high-school students (18 years old) without subjective complaints or objective structural or functional disorders of the temporomandibular joint were studied by means of articulation paper. From that sample 41 students with intact dentition and orthognathic occlusion were selected. The first mandibular molars (N = 77) were studied. The results are as follows. The occlusal contacts in the first mandibular molar vary from 1 to 7. The greatest percentage of contacts is observed in the tubercles. In the first mandibular molar the biting pressure upon the tubercle apex areas is greater compared to that on the sloping areas. Our results were compared with the findings obtained by the other three methods mentioned above. Our method allows objective specification of the topographic distribution of occlusal contacts.

Adolescent↗
PubMed1996

Side reactions in the pyroglutamic acid-7-amino-4-methylcoumarin synthesis.

N-Formylpyroglutamic acid-7-amido-4-methylcoumarine and pyroglutamyl-pyroglutamic acid-7-amido-4-methylcoumarin are the major products in the synthesis of pyroglutamic acid-7-amido-4-methylcoumarin by phosphorus pentachloride in dimethylformamide and dicyclohexylcarbodiimide under pyridine activation.

Chlorides↗
PubMed1995

[The restoration of the weight-bearing capacity of the lower extremities and the gait of patients with traumatic detachments].

The functional recovery terms are estimated in 65 patients presenting extensive traumatic detachments (decollement) and defects of the lower extremities. The series includes 40 children (61.5 per cent), and 25 adult individuals (38.5 per cent). The distribution of patients by gender, age, surface involved by the lesion, its location and concomitant damage to deep anatomical structures is studied. The patients are subjected to 2-8 years postoperative follow-up. According to type of intervention, they are distributed in three groups, as follows: group one--patients with reimplantation, group two--reimplantation with ensuing necrosis, and group three--cases presenting granulation wounds on admission. The results are evaluated by the static loadbearing test of Buglaev and ichnography, and subjected to statistical processing by variation analysis. As shown by the results, maximal functional recovery in group one is attained by the end of the first year, in group two--by the end of the second year, and in group three--by the end of the fourth year. Application of early exercise therapy, individually prescribed, contributes to the positive outcome.

Adolescent↗
PubMed1994

Oral hygiene and gingiva status in school children aged 7 to 14 from Plovdiv.

An assessment of the oral hygiene and periodontal health was made in 1596 school children (777 boys and 819 girls) aged 7-14 years from randomly selected classes and schools in Plovdiv, Bulgaria. The oral hygiene status of the school children assessed by the plaque indexes (PLI) of J. Greene and J. Vermillion, and that of J. Silness and H. Löe was found to be rather poor. The relative share of subjects with plaque index of 0.00 to 1.00 was found to increase with age for both sexes. The relative share of children with chronic catarrhal gingivitis was 42.61 +/- 2.34 indicating the necessity of active prophylaxis and treatment of the disease. A tendency was observed towards an increase of the disease incidence in comparison with data obtained in a 1983 study. A correlation between the hygiene status and chronic gingival inflammation in 14-year-old school children was found.

Adolescent↗
PubMed1991

Combined dermatoplasty in deep burns in the region of flexion of the large joints in children.

In 13 children with deep burns in the region of functionally important anatomical flexions, the wounds were covered with rotation skin flaps from the vicinity. The purpose of the method used is the prevention of post-burn contractures, which are particularly expressed in the process of the child's growth. After observation of the operated patients over 3 years, the results of operation justify the conclusion that it is purposeful to utilize skin resources from the vicinity of the wound surface to achieve more rapid and more effective restoration of anatomical integrity and function in deep burns on flexions of the body.

Burns↗
PubMed1989

[Health status of schoolchildren under five-day-week school program].

The effect of a five-day educative programme is studied with respect to the health status and morbidity of schoolchildren--from entering VIIth class in the Unified secondary professional school to completion Xth class. The data received are compared with the results from health exam on children, trained on six-day week. The results from the investigation show more favorable dynamics of the chronic, acute and neuro-psychic morbidity, the per cent of those frequently taken ill and is increased the number of healthy schoolchildren. In comparison with the traditional educative organization the five-day week programme has higher prophylactic effectiveness in the health protection of schoolchildren.

Bulgaria↗
PubMed1989

[The interferon reaction of the leukocytes in newborn infants and their mothers].

The interferon reaction of leucocytes (IRL) in the newborns and their mothers were examined in vitro. The ability of leucocytes, obtained from the blood of the umbilical cord of newborns, to synthesize interferon was established in 48.78% of the investigated newborns while in their mothers the relative part was 70.73%. The mean geometrical titre of the leucocytic interferon was lower than that of the parturients (30.90-1.02 against 41.69-1.70).

Adult↗
PubMed1986

[Natural immunity of the pupils in a secondary vocational and technical school for rubber and plastics].

In connection with the reconstruction of the educational system and occupational training of the youths, the problem of the effect of the occupational factors on the organism of the juveniles is of exceptional importance. The search of early changes by the application of immunological tests in that aspect is very rational. The state of microflora of the deep layers of the skin, the microbic contamination of nasal mucosa have been studied as well as the content of complement in serum and serum immunoglobulins G, A and M and the phagocytosis in the students from SPTS. The experimental subjects have exposed to a complex of toxic-chemical substances with different intensity during their occupational training and practice. It has been established that the training under the specific conditions for mastering the specialty has led to a slight decrease of the antimicrobic resistance and reduction of the phagocytic function of leukocytes, not affecting the humoral factors of natural immunity.

Adolescent↗
PubMed1985

[Health status of 1st- to 3d-grade pupils in a unified secondary polytechnical school entering school at different ages].

The purpose of the present work is to study the effect of training in the new unified secondary polytechnical school /USPS/ on the health status of students from I-III class, with initial school age 6 and 7 years, realized in the conditions of 5-day school week and all day organization of the training process. A longitudinal observation /I to III class/ on the health status of 6 divisions of schoolchildren in Sofia and Burgas is performed--on those starting at the age of 6 /experimental/ and 7 years /controls/. Besides a transversal investigation of a total number of 1657 students of I-III class in 10 districts of the country was carried out, distributed in like manner between 6 and 7 years old schoolchildren. On each stage of the study were made medical examinations with paraclinical ones /blood and urine/, and during every school year information has been gathered for all cases of acute diseases. It was established that the health status of the examined schoolchildren of I-III class of the unified secondary polytechnical schools, evaluated on the basis of data taken from the acute and chronic somatic diseases is good. There are no abrupt differences in the health of both compared groups of schoolchildren. A slight tendency for deterioration of the health is observed among those starting school at 6 years.

Acute Disease↗