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Biomedical subjects

S Todorović

Publications and source records attributed to S Todorović.

At least 19 recordsLinked to original sources
PubMed2005

Haplotype analysis of the DM1 locus in the Serbian population.

OBJECTIVES: Analysis of the CTG-repeat number and three biallelic markers, Alu(+/-), HinfI(+/-), and TaqI(+/-), in the DMPK gene in healthy and myotonic dystrophy type 1 (DM1) Serbian individuals. Also, the consideration of haplotypes in the light of the proposed models of CTG-repeat evolution and origin of the DM1 mutation. MATERIALS AND METHODS: Markers were analyzed by PCR and haplotypes were obtained on 203 unrelated normal chromosomes and 24 unrelated DM1 chromosomes. RESULTS: A strong linkage disequilibrium was detected between the three biallelic markers alone (P <0.0001) and between distinct CTG-repeat size classes and reconstructed haplotypes. Greater than 98% of normal chromosomes contain (+++) and (- - -) haplotypes. The (+++) haplotype is the most common, while the (CTG)(9-17) are the most frequent alleles. We found a complete association of (+++) haplotype with (CTG)(> or =18) and mutated alleles. CONCLUSIONS: (CTG)(9-17)/(+++) haplotype is the ancestral haplotype and DM1 mutation occurred on (CTG)(18-35)/+++ chromosome.

Case-Control Studies↗
PubMed2001

Is the 31 CAG repeat allele of the spinocerebellar ataxia 1 (SCA1) gene locus non-specifically associated with trinucleotide expansion diseases?

A number of human hereditary neuromuscular and neurodegenerative disorders are caused by the expansion of trinucleotide repeats within certain genes. The molecular mechanisms that underlie these expansions are not yet known. We have analyzed six trinucleotide repeat-containing loci [spinocerebellar ataxias (SCA1, SCA3, SCA8), dentatorubral-pallidoluysian atrophy (DRPLA), Huntington chorea (HD) and fragile X syndrome (FRAXA)] in myotonic dystrophy type 1 (DM1) patients (n = 52). As controls, we analyzed two groups of subjects: healthy control subjects (n =133), and a group of patients with non-triplet neuromuscular diseases (n = 68) caused by point mutations, deletions or duplications (spinal muscular atrophy, Charcot-Marie-Tooth disease, type 1A, hereditary neuropathy with liability to pressure palsies, and Duchenne and Becker muscular dystrophy). Allele frequency distributions for all tested loci were similar in these three groups with the exception of the SCA1 locus. In DM1 patients, the SCA1 allele with 31 CAG repeats account for 40.4% of all chromosomes tested, which is significantly higher than in two other groups (11.3% in healthy controls and 6.6% in the group of non-triplet diseased patients; P < 0.001, Fisher's exact test). This is consistent with our previous findings in HD patients. The absence of this association in non-triplet diseases as well as in healthy controls could indicate a possible role of this SCA1 allele with 31 repeats in triplet diseases. Here we discuss a possible role of the SCA1 region in pathological trinucleotide repeat expansions.

Alleles↗
PubMed1998

Influence of pyridine and urea on the rat brain ATPase activity.

The neurotoxicity of pyridine and urea was investigated in respect to their ability to alter the activity of synaptosomal membrane Na+/K(+)-ATPase and Mg(2+)-ATPase. In vitro treatment with pyridine and urea stimulated Na+/K(+)-ATPase activity in a dose-dependent manner up to 40% and 60%, respectively. Mg(2+)-ATPase activity increased up to 40% after pyridine treatment, while urea had no effect at all. The neuroactive potencies of pyridine and urea were evaluated by estimating parameters Km and delta Vmax for enzyme stimulation, as well as Hill coefficient to estimate the levels of cooperativity for pyridine and urea binding. The results suggest that pyridine stimulates both enzymes, probably by interacting with some neuronal membrane components, and altering the lipid micro-environment of the ATPases. In contrast, urea stimulates the Na+/K(+)-ATPase only, assumingly by acting on it directly or via some other regulatory mechanism. Stimulation of Na+/K(+)-ATPase and Mg(2+)-ATPase by the substances tested and subsequent alteration of neuronal cell functioning could contribute to the CNS dysfunction upon chronic exposure to pyridine and urea.

Animals↗
PubMed1996

Association of Krabbe leukodystrophy and congenital fiber type disproportion.

Hypotonia and weakness developed in a 12-month-old boy whose psychomotor development had previously been normal. The muscle biopsy demonstrated a disparity in the mean diameters of type 1 and type 2 fibers and satisfied major histologic criteria for diagnosis of congenital fiber type disproportion (CFTD). However, deterioration of motor and mental function, which developed subsequently, strongly suggested progressive encephalopathy. Examination of leukocyte cerebral enzymes at 15 months of age revealed a complete lack of galactosylceramide-beta-galactosidase. Selective type 1 fiber atrophy with type 1 fiber predominance has been observed in various conditions, including Krabbe disease. We report an additional case of Krabbe leukodystrophy associated with CFTD. The finding on the molecular level will resolve the dilemma of whether CFTD is a congenital myopathy or whether these patterns of disproportion may result from a number of different processes that interfere with the maturation of the developing motor unit.

Fatal Outcome↗
PubMed1990

5-HT2 and 5-HT3 receptors mediate two distinct depolarizing responses in rat dorsal root ganglion neurons.

The effects of serotonin (5-HT) were studied on transmembrane potentials in 188 rat dorsal root ganglion cells (150 A-type, 16 C-type and 22 unidentified neurons). 5-HT produced a concentration-dependent depolarization in 88% of these neurons. Membrane input resistance (Rin), determined from the slope of current-voltage displacement curves, was increased in 51% and decreased in 41% of the responding neurons. Both responses occurred in 8% of the neurons. No differences in these responses were observed between A- and C-type neurons. Norepinephrine (NE) depolarized 75% (n = 20) of the neurons tested while increasing the Rin. In cells where 5-HT decreased Rin, 2-methyl 5-HT, but not alpha-methyl 5-HT, mimicked the response. The selective 5-HT3 antagonist, ICS 205-930, blocked this response, but ketanserin and methiothepin did not affect it. The 5-HT-induced increase in Rin was blocked by 5-HT2 antagonists (ketanserin, methiothepin and spiperone); mimicked by alpha-methyl 5-HT, but not affected by 2-methyl 5-HT. The selective 5-HT3 antagonist, ICS 205-930, did not antagonize this response. The action of NE but not 5-HT was blocked by the selective alpha 1 antagonist, prazosin. These data indicate that the 5-HT induced depolarization with decreased Rin is mediated by 5-HT3 receptors and the depolarization with increased Rin is mediated by 5-HT2 receptors. Furthermore, these two receptors can occur on the same cell.

Animals↗
PubMed1989

Rigid spine syndrome and progressive external ophthalmoplegia in a 15-year-old girl.

A 15-year-old girl presented with rigid spine syndrome (RSS) associated with a myopathy of benign course, marked proliferation of perimysial and endomysial connective tissue, severe scoliosis, and progressive paralysis of upward and lateral gaze. This is the first report of RSS and progressive ophthalmoplegia in the same patient.

Adolescent↗
PubMed1979

[Allergic reactions in cytostatic therapy].

The cytostatics used in treatment of malignant diseases may, similar to other drugs sensibilize the organism and cause various allergic manifestations. The authors present 6 children with malignant diseases in whom various allergic reactions, from urticaria to a severe form of Stivens-Johnson syndrome, were observed to appear during the treatment with cytostatics. All symptoms of allergy withdrew after the administration of antihistaminics. Difficulties in differential diagnosis of an allergy and tocsic effects of cytostatics are also pointed out.

Adolescent↗
PubMedDate not supplied

[Deletions in the dystrophin gene and its phenotype expression].

About 60% of both Duchenne's muscular dystrophy (DMD) and Becker's muscular dystrophy (BMD) is due to deletions of dystrophin gene. For cases with deletion mutations the "reading frame" hypothesis predicts that deletions which result in disruption of the translation reading frame prevent production of stable protein and are associated with DMD. In contrast, intragenic deletions that involve exons encoding an integral number of triplet codons maintain proper reading frame. The resulting abnormal proteins are stable and partially functional, resulting in a milder and more variable BMD phenotype. To test the validity of this theory,we analyzed 40 patients-19 independent deletions at the DMD/BMD locus. Clinical/molecular correlations based on the altera-tions of the reading frame were valid in 69.2% of cases. After exclusion of: --2 patients with del 3-6 (with no consistent clinical expression); --1 DMD patient with large in-frame deletion; --2 patients that were too young to be classified; --4 patients in whom it was impossible to identify the extent of deletion (del 47 and del 44-45), the correlation between deletion and clinical severity was as predicted in 92.4% of cases. The present data should be useful in establishing the prognosis in individual patients even in sporadic cases with no affected relatives.

Dystrophin↗
PubMedDate not supplied

[Hardness of composite materials used for restoration of front teeth].

The evaluation comprised four anterior two-components composite materials: concise-"B", concise-"T", adaptic and silar and six anterior one-component composite materials: heliosit, visio-dispers, visio-fill, durafill, estilux and prisma-fill. The Amsler press of 600-2000 kg was used for evaluation of hardness on pressure, flexion and extension of 10 composite materials using the original "accessory apparatus" PAC-s and PAC-e. For evaluation of hardness 15 samples of each material were made. On the basis of the results obtained it has been concluded that no evenly regular dependence exists among the evaluated hardness of different composite materials so it is necessary to evaluate all three hardness for their adequate categorization. Taking into account levels of all three hardness, AJKM was recommended as better material than ADKM, while some of them are much better (such as estilux, prisma-fill and visio-fill) for restoration of angular defects of teeth structures of crowns of anterior teeth.

Dental Materials↗
PubMedDate not supplied

[Composite inlay].

Explore the source record for details and available documents.

Acrylic Resins↗
PubMedDate not supplied

[Use of enamel-dentin adhesive in the restoration of defects in the cervico-root region of teeth].

The incidence of cervical defects was epidemilogically studied on a sample of 60 teeth with periodonatl disease and cervical defects which were classified in three groups. Also, the control clinical prospective study comprised 44 esthetic external restorations made of monocomponent resin (Heliosit and Visio-Disperse) and bicomponent resin (Silar and Dentosit) in the cervico-radical region of the vestibular surface od teeth with periodontal disease. Enamel-dentin adhesive was used as a bonding agent. Two parameters were followed up: 1. restoration margin staining, and 2. retentional state of restoration. The studies have shown that: a) the cervico-radical defects affecting both the dentin-coronary third of the root and the dentin-cervical third of the crown were found in 64% of subjects with periodontal disease and cervical defects requiring application of monocomposite resin in the same percentage, b) enamel-dentin adhesive+ composite restorations made of monocomposite resin showed changes in both mentioned parameters in a significantly lower percentage being of markedly smaller intensity than those made of bicomposite resins, and c) bonding capacity of enamel-dentin adhesives is an important additional factor of retention of esthetic restorations made in the cervico-radial dental region.

Acrylic Resins↗
PubMedDate not supplied

[The rigid spine syndrome].

Five patients with the clinical picture of rigid spine syndrome are presented. Three of them were females. All these patients fulfilled the clinical criteria for rigid spine syndrome. On the basis of the analysis of these patients and the data from literature, it was established that Dystrophia musculorum progressiva--Emery-Dreifuse was one of the causes of rigid spine syndrome in one patient. In the other four patients unspecific myopathic changes were found. The only common feature was marked proliferation of endomysium and perimysium (connective tissue). An effort was made to solve the nosological problems on the contemporary level of knowledge. The heterogenous group of rigid spine syndrome was divided into the three subgroups: 1) Rigid spine syndrome with nosologically determined neuromuscular disorder; 2) Rigid spine syndrome on myopathic basis, but nonspecific and unrecognizable as an entity; 3) Rigid spine syndrome with disorders of non-neuromuscular origin, but with that related to bones, joints or connective tissue.

Adolescent↗