Molecular characterization of rotaviruses circulating in the population in Turkey.

Of a total of 508 stool specimens from children with acute diarrhoea, mostly under the age of 5 years, collected in nine cities in the western and southeastern regions of Turkey between May 2000 and October 2002, 119 (23.4%) were found positive for rotaviruses (RV) by ELISA. Positive samples were characterized by electropherotyping and G and P genotyping. A subset of G and P types were confirmed by nucleic acid sequencing. The most prevalent types found in this collection included G4P[8], accounting for 27/64 (42.2%) of the fully characterized strains. G1P[8], G2P[4] and G3P[8] were found in 17 (26.6%), 2 (3.1%) and one (1.5%) samples respectively. Less common strains such as G9P[8] were found in two (3.2%) samples and G2P[8], G1P[6], G2P[6] and G4P[6], possible reassortant viruses, were found in five (7.8%), 2 (3.1%), one (1.5%) and four (6.3%) samples respectively. Mixed infections were found in six (7.3%) samples and were associated with combinations of G1 + G2, G1 + G4, G1 + G9 and G4 + G9 strains. This is the first molecular epidemiology study of its kind to be carried out in Turkey and suggests a significant diversity of co-circulating rotavirus strains.

Formalin fixing and paraffin embedding may lead to extra band development in PCR.

The molecular biological analysis of infectious agents requires the availability of a reliable source of microorganisms to be used to recover DNA. Clinical samples can be obtained directly from infected patients or can be propagated using in vitro or in vivo systems. However, repeated sampling from patients is not always possible as the procedure may be invasive or unpleasant, or it is not possible to catch the same agent at the time of second sampling. Moreover, the techniques used may also produce false-positive and false-negative results. We therefore studied the impact of formalin-fixing and paraffin embedding on tissue sampling, and the methodologies such as DNA isolation and PCR amplification of DNAs from archival materials in the diagnosis of Mycobacterium tuberculosis. PCR analyses were done according to standard methods with some modifications. Demonstration of mycobacteria was successful both in tissue sections of the formalin-fixed lymph nodes and in stained fresh materials from patients. However, the results showed the presence of two extra bands in the gel. We accounted for extra band development due to the harshness of the methodology used to isolate nucleic acids from formalin-fixed and paraffin embedded tissue samples or the nature of the fixation procedure, or because of the time passed during storage in which alteration in the chromosomal DNA would take place. Thus, if disease- and tissue specific morphological features, such as sample size, type of fixation, and intralesional heterogeneity are ignored, errors because of sampling and methodologies used may lead to false-positive and false-negative results.

Possible association of temporomandibular joint pain and dysfunction with a polymorphism in the serotonin transporter gene.

The purpose of this study was to evaluate the relationship between temporomandibular joint pain and dysfunction and serotonin transporter (5-HTT) gene polymorphism. Forty-eight patients with temporomandibular joint pain and 111 healthy control subjects were examined. The results for the patients and control subjects were not significantly different (P >.05). The analysis of genotype distribution (homozygous for STin 2.10 genotypes of the variable-number tandem-repeat polymorphism) showed significant differences between the patients and control subjects (P =.003). ST 2.10 allele was more frequent in the patients with temporomandibular joint pain and dysfunction. In the control group, however, STin 2.12/12 genotype was significantly higher (P =.017). In the patients who were homozygous or heterozygous for variable-number tandem-repeat variants of 5-HTT STin 2.12 copies, the average scores of somatization and anger were significantly higher than those who were homozygous for STin 2.10 variant (P <.05). The patients who were homozygous for STin 2.10 genotype were also homozygous for "L" genotype (P =.019). However, this was not the condition in the control subjects. This study does not provide evidence to support the involvement of 5-HTT gene-linked polymorphic region in temporomandibular joint pain and dysfunction. Our findings indicated that only the presence of the homozygous STin 2.10 genotype of variable-number tandem-repeat is likely to play a substantial role in the genetic predisposition to temporomandibular joint pain and dysfunction and that the STin 2.12/12 genotype may have a protective role against temporomandibular joint pain and dysfunction.

Significance of serotonin transporter gene polymorphism in migraine.

OBJECTIVE: To elucidate significance of the serotonin transporter gene (STG) polymorphism in migraine, and to address the polymorphic patterns of STG, both in the migraineurs and healthy people in this country. STUDY DESIGN: A PCR study of STG in 52 migraineurs and 80 healthy controls. METHODS: Using the PCR technique, STG polymorphism was studied in the DNA obtained from leukocytes of the patients and healthy controls. Polymorphism of the two regions (VNTR and 5-HTTLPR) of STG was assessed. RESULTS: VNTR STin 2.10 and STin 2.12 alleles were detected in migraineurs and healthy controls. Both homozygous and heterozygous STin 2.10 allele predominated in the migraine group (p=0.01), while STin 2.12 allele was more frequent in the healthy controls (p=0.02). There was no relationship between the migraine type, family history of migraine and STG polymorphism. CONCLUSION: STin 2.10 and STin 2.12 alleles of VNTR are frequent in this country. While the presence of STin 2.10 allele increases the risk of migraine, 5-HTTLPR polymorphism is not associated with this risk.