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Biomedical subjects

J Jordanov

Publications and source records attributed to J Jordanov.

At least 19 recordsLinked to original sources
PubMed1992

Structural investigations by extended X-ray absorption fine structure spectroscopy of the iron center of mitochondrial aconitase in higher plant cells.

We have obtained iron K-edge extended x-ray absorption fine structure spectra of the plant mitochondrial aconitase in its active state, in the presence (aconitase (+)) and absence (aconitase (-)) of the substrate citrate. Analysis of the data indicates that oxygens are present in the first coordination shell, at an average Fe-O distance of 1.96/1.98 A (aconitase (+)/aconitase(-)). Part of these oxygens is provided by the citrate, which binds at 1.99 A from the iron in aconitase (+). The second shell (sulfur) contribution is split and is consistent with Fe-S distances of 2.30/2.29 and 2.56/2.59 A, and the third shell (iron) is consistent with an Fe-Fe distance of 2.83/2.84 A. Both Fe-S and Fe-Fe distances are longer than similar distances found in most Fe-S centers. A strong scattering at approximately 5 A has been identified as originating from an iron atom which is near to, but not part of, the Fe-S cluster. These data indicate that active plant mitochondrial aconitase contains a novel type of iron center.

Aconitate Hydratase↗
PubMed1988

Symbolic trepanations of skulls from the Middle Ages (IXth-Xth century) in Bulgaria.

Symbolic trepanations (ST) of skulls (IXth-Xth century) found in north-eastern Bulgaria near the West coast of the Black Sea were Studied. It was established that trepanations were performed on subjects well over the age of thirty and cover 41% from the total material which is the highest frequency documented so far. Tracks of the ST are localized most often on and round the sagittal suture, bregma and lambda. Their number ranges from 1 to 9 per cranium with a diameter of 3-4 to 20-28 mm and a depth of 1 to 6 mm. They are usually round and encircled with a prominent ridge. In this article we try to explain the reasons for the symbolic trepanations as well as the link between the traditions of the ancient Turkish nations and Chinese medicine.

Adult↗
PubMed1984

Effects of steroid sex hormones on chick embryo gonads in organ culture, with special reference to hormonal control of gonadal sex differentiation.

At the initial stages of sex differentiation (7.5 and 8.5 days of incubation), chick embryo gonads were treated directly with testosterone or estradiol-17 beta in organ cultures. Chemically-defined media containing cholesterol as a steroid precursor were used. The differentiation of gonads in the 10 to 12-day controls, cultured in media containing no hormones, was close to that of gonads of equivalent age in ovo. Testosterone added to the medium exerted an inhibitory effect on the cortex of the female gonad and a masculinizing one on its medulla. The results of estradiol treatment confirmed the known feminizing effect of that hormone on the male gonad, the meiotic prophase in the genetically male germ cells being initiated in the induced cortex. These data may be interpreted in favour of a bihormonal theory of gonadal sex differentiation in birds, where the predominantly-synthesized male or female hormone in the gonad determines the male or female pattern of development of the corresponding gonad.

Animals↗
PubMed1978

Interaction of the anti-tumour drug cis-Pt(en)Cl2 with Cytidilyl-3'--5'-guanosine.

Chemical shifts occurring in 1H nuclear magnetic resonance and Sephadex G 25 chromatography are used to follow the reaction of the dinucleotide C3'p5'G (cytidilyl-3'phosphate5'-guanosine) in aqueous solution and to separate its products. Binding of the platinum occurs in first place at the cytosine, then at the guanine base. Two major complexes are produced, Pt:CpG and (Pt:CpG)2, which account for respectively for an internal and an external cross-linking effect.

Antineoplastic Agents↗
PubMed1978

[Relationship between the retromolar space and the mandibular measurements in Bulgarians].

We examined 412 mandibles from adult males. Using the classic anthropometric methods according to Martin-Saller, we took 17 measurements: length, width, height and angle of the mandible. The data obtained were subjected to variance and correlation analyses. We observed poor correlations for the length of the dental arch, the height of the ascending ramus, the condylar width and the width of the chin; there were medium correlations for the following measurements: mental plane, median plane and angular width in the region of 46, 47, 36, 37 and the thickness of the alveolar portion. The correlations for all the other measurements were high; in some cases, they approximated the normal value.

Adult↗
PubMed1978

[Asymmetry in the structure of the middle part of the facial skull].

The results of study of the middle third of the facial region, performed on a total of 412 skulls of male individuals, lead to the following conclusions: 1. In the investigated upper section, the zygomatic bone inclusive, downwards to its lower section along the alveolar process of the maxillary bone, a complete and approximative symmetry displayed by the width values is more frequently met with, whilst asymmetry is rather rarely. In the same direction, from above downwards, the number of skulls with differences in favour of the right side decrease, whereas the number in favour of the left side increase, with the rarely observed asymmetry in the lowermost section usually involving the leftside. 2. The height of the upper jaw-bone region near the sagittal line shows more frequently symmetry (complete and approximative), and rather rarely asymmetry, whilst insofar as the zygomatic bone is concerned the opposite is observed; therefore, in the direction from medial to lateral-wards the incidence of asymmetry increases, whereas that of the symmetry decreases. In the same direction the number of skulls with differences in favour of the right side increases, while the number in favour of the left side decreases. 3. The coincidence of absolute differences recorded in 69%, respectively 61.6%, between right and left side of closely positioned dimensions (20 and 31, resp. 20 and 42) proves that the data about these dimensions are apt to determine symmetry and asymmetry manifestations with a sufficient reliability. 4. The individual values of the pairs of breadth dimensions of one and the same region of the studies craniofacial portion show a higher degree of correlation than those of different regions which is due to the differences between the latter in terms of incidence of symmetry and asymmetry in their build up. 5. The width of the middle third of the median craniofacial portion and the lateral distance of the skull Zygomaxillare--Porion do not correlate, i.e. there is no parallelism between the fluctuations of their individual values. 6. In most of the cases the bones of the external nose are symmetrical, and hence its asymmetry is attributed to the soft parts as cartilage and skin.

Bulgaria↗
PubMed1978

Ultrastructure of developing interstitial cells in chick embryonic gonad in relation to their genesis and steroidogenic function.

Electron microscopic studies on the development of interstitial (steroidogenic) cells in embryonic chick gonads were carried out in a chronological sequence from the time of their appearance to the end of incubation, in a comparative aspect in both female and male sexes, and through a comparison with light microscopic findings. An asynchrony in the development of these cells in both sexes is established. In the ovaries (left and right) individual steroidogenic cells are detected for the first time towards the 7th embryonic day, grouping themselves towards the 9th...10th embryonic day in nests, interstitial organoids. In the testis this takes place towards the 10th and 14th...15th days, respectively, the interstitial organoids forming as incomplete muffs around the seminiferous cords and later on (towards the 16th embryonic day) also as nests in stroma. On the basis of observations that the precursers of the steroidogenic cells differentiate within the sex cords (first proliferation) and separate from them, falling into the stroma, the authors adopt the concept of the mesothelial (epithelial) origin of those cells. Particular protrusions (multivesicular structures) of the cytoplasm of the interstitial cell are described whose role is believed to be connected with the mechanism of the steroid secretion of the gonads. The results are discussed in relation to some biochemical and experimental data on the morphogenetic function of the embryonic sex hormones.

Animals↗
PubMed1978

Adaptation of the ammoniacal silver reaction to cytochemical demonstration of myelin basic protein.

A modification of Black and Ansley's ammoniacal silver reaction (ASR) for histones is proposed for visualizing myelin basic protien (MBP) in the nervous system. The reaction is performed on histological sections of tissues fixed in neutralized formalin-alcohol and delipidized in the course of the routine paraffin embedding. The deparaffinized sections are again treated with formalin in order to make the "unmasked" by the delipidization basic groups of MBP reactive to ammoniacal silver. After treatment with this reagent MBP of the myelin sheaths of the nerve fibres is impregnated brownish-black. Deparaffinized sections subjected to an extraction of MBP with hydrochloric acid exhibit a negative reaction at the level of the myelin sheaths the same reaction being preserved at the level of the nuclear histones. The reaction is positive in paper spots of nervous tissue extracts obtained with the same acid. These assays indicate the specificity of the modified ASR. The method can be used for studies on the processes of myelination and demylination in normal histogenesis and in pathology of the nervous tissue.

Animals↗
PubMed1976

On the cytochemical demonstration of basic proteins in the cell nucleus, including the nucleolus.

A combined Feulgen-alkaline fast green method is described for simultaneous demonstration of DNA and basic proteins in the cell nucleus. The method is based on preserving both types of substances in the tissue section and releasing in them reactive groups for the 2 kinds of staining. These conditions are best provided, as proved by staining tests on tissue hydrolysates, if formalin-containing mixtures (SERRA's or LILLIE's fluids) are employed for fixation, and cold 5 N HCl is used for FEULGEN hydrolysis. In this way, a good cytological picture is also achieved. Nuclear euchromatin stains with this method red, while heterochromatin, pycnotic nuclei and sperm heads exhibit a deep violet to blue-violet colour. Prominent nucleoli of metabolically active cells display a distinct blue-green staining thus manifesting their high content of basic proteins. Acetylation test reveals that these proteins are of lysine-rich type. The known negative reaction of the nucleoli with the routine alkaline fast green method according to ALFERT and GESCHWIND must be attributed to an extraction of the nucleolar basic proteins with the hot TCA used in this method. Certain analogy in the cytochemical behaviour between the nucleolous and the chromatin under various conditions of hydrolysis leads to the suggestion that the nucleolar basic proteins demonstrated should be in the form of a ribonucleoprotein complex, probably of the pre-ribosomal material of the nucleolus.

Animals↗
PubMed1976

[Asymmetry in artificially deformed skulls from a Protobulgarian mass grave of the 9th century].

A series of 18 skulls with pronounced asymmetry, picked up out of a total of 52 artificially deformed and accordingly restored skulls are studied. It is a matter of material discovered in a circular tomb near by the village of Devnja, dating back to the end of the 9th century. To obtain metrical determination of the asymmetry, the authors performed measurements of chords, resp. arches between the anthropological points sphenion and asterion, as well as of the distance from the latter and from the porion on either side up to the glabella, inion, bregma and lambda. Besides the 18 sizes directly recorded, 18 chords constructed on the craniograms (three per skull) mainly between the above mentioned points were also utilized. For each dimension the absolute differences between left and right, the mean value of the differences and the asymmetry index after Duncker were calculated. Using the method outlined, an accurate and quantitative determination was made of the asymmetry both in the occipito-parietal and temporo-clinoidal parts of the skull (compensatory and persisting asymmetry). It is demonstrated that the discrepancies between some of the size values established in individual skulls, and the skull asymmetry, recorded scopically with other measurements, are due to displacements of the anthropological points (sphenion, asterion, inion), produced by differences in growth rate and size of bones. The arrested development of bones and the resulting depressions along their surfaces under the effect of the artificial deformation dressing are of utmost importance for the processes developing within the deformed skulls.

Anthropology, Cultural↗