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Biomedical subjects

M Stevanović

Publications and source records attributed to M Stevanović.

At least 19 recordsLinked to original sources

Campomelic dysplasia and autosomal sex reversal caused by mutations in an SRY-related gene.

Induction of testis development in mammals requires the presence of the Y-chromosome gene SRY. This gene must exert its effect by interacting with other genes in the sex-determination pathway. Cloning of a translocation chromosome breakpoint from a sex-reversed patient with campomelic dysplasia, followed by mutation analysis of an adjacent gene, indicates that SOX9, an SRY-related gene, is involved in both bone formation and control of testis development.

Amino Acid Sequence

SOX3 is an X-linked gene related to SRY.

The mammalian genome contains a family of genes that are related to SRY, the mammalian sex determining gene. The homology is restricted to the region of SRY that encodes a DNA binding motif of the HMG-box class. These genes have been named SOX genes (SRY-related HMG-box genes). We have cloned and characterised SOX3, a member of the human SOX gene family. SOX3 maps to the X chromosome in the region Xq26-27. A mentally retarded male patient with haemophilia B is deleted for both the Factor IX gene and SOX3. This suggests that SOX3 is not essential for testis formation. The phenotype of the patient and the expression of SOX3 gene in neuronal tissues raises the possibility that this gene is a candidate gene for Borjeson-Forssman-Lehmann, an X-linked mental retardation syndrome.

Adult

Origin of rat beta-globin haplotypes containing three and five genes.

We have reported in rat three adult beta-gene haplotypes containing either five or three genes. Detailed sequence analysis reveals that the leftmost gene is the major gene and that at the opposite end downstream lies the minor gene. All of the genes lying between them are minor-major hybrids indicating their origin by unequal crossing-over. In two haplotypes beta-globin genes were found with an L1(1) element inserted directly into IVS2. The described results allow the formulation of a pathway of mutational events leading from the ancient two-beta-gene rodent ancestor through a three-gene haplotype to five-gene haplotypes, one of which is postulated to have arisen in common laboratory strains since their capture in the wild.

Animals

Variant chromosomal arrangement of adult beta-globin genes in rat.

The genomic organization of three haplotypes of beta-globin genes was determined to resolve the question of the number of those genes in rat. Haplotype a, found in inbred strain DA, has three genes or pseudogenes, while haplotypes b, found in AO, Y5 and Wistar strains, and c, found in Wistar strain, have five genes or pseudogenes each. In haplotypes b and c, the first gene is of beta major type and the remaining four are of beta minor type. Partial sequencing of six out of 13 genes shows that duplications of beta minor genes are causing polymorphism in a number of genes. Also, in haplotype b two beta minor genes have a 6.5-kb intron 2, while in haplotype c only one beta minor gene contains such a large intron 2. The three structurally different haplotypes described are not interconvertible by single recombination events. The results indicate that the rat has the highest number of adult beta-globin genes found in mammals so far.

Amino Acid Sequence

[Successful autotransplantation of intra-abdominal testes into the scrotum using microvascular technics].

The surgical treatment of undescended and nonpalpable testes still remains controversial. The shorter the vascular stem, the greater difficulties are during orchidopexy. The results of the formerly used "stage" and "Loop" techniques are unsure and frequently lead to postoperative atrophy of the testes. Thanks to the marked development of the microsurgical technique, over the past 10 years, besides the conventional methods for orchidopexy of the testes with a short vascular stem, microvascular revascularization on the autotransplanted testes from the abdomen into the scrotum is also used. During the last year two boys were successfully operated upon with this method with which this microvascular anastomosis technique is described and the problems openly discussed.

Adolescent

Limited polymorphism of both classes of MHC genes in four different species of the Balkan mole rat.

We analyzed the restriction fragment length polymorphism of class I and class II MHC genes in DNA from 20 individuals belonging to the four different species of the complex of species of Balkan mole rats Spalax leucodon captured at four different localities in Yugoslavia. All populations were tested with four restriction enzymes and one conserved mouse probe for each of the two classes of MHC genes. The probes employed detect either limited polymorphism of class I genes or lack of polymorphic bands containing class II genes. Of the two other subterranean rodents that have been studied, four karyotype forms of the Israeli mole rat show polymorphism in both classes of MHC genes similar to the one found in all other mammals (Nizetić et al. 1985), and the Syrian hamster shows limited polymorphism of class I genes and high polymorphism of class II genes (McGuire et al. 1985). Balkan mole rats belong to a new group in this respect, different from all mammals studied so far, since they apparently show limited polymorphism of both classes of MHC genes.

Animals

Simultaneous fractures of the distal end of the radius and the scaphoid bone.

Simultaneous fracture of the scaphoid bone occurred in 26 (4%) of the 650 injuries of the distal end of the radius seen at our institution. These injuries occur after a fall on the outstretched hand with a pronated wrist joint and extended hand. In a 4-year period (1983-1987), 26 simultaneous fractures of the distal end of the radius and the scaphoid bone were seen. Typically, the fracture of the radius had minimal or slight displacement, and the fracture of the scaphoid bone occurred always as a transverse thin line without displacement. The simultaneous fracture of the scaphoid bone was often very difficult to recognize radiographically and could very easily be overlooked. Discovery of the simultaneous fracture is important for adequate immobilization. Inadequate treatment, due to an overlooked fracture of the scaphoid bone, can result in a painful wrist joint and, possibly, Sudeck's atrophy.

Adolescent