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Biomedical subjects

M Simsek

Publications and source records attributed to M Simsek.

At least 19 recordsLinked to original sources
PubMed2001

Investigation of the vertebrobasilar arterial system in vertigo by vestibulocochlear test, SPECT and angiography.

OBJECTIVE: Perfusion of the areas of cochleovestibular structures was investigated using Tc-99m HMPAO single photon emission computerized tomography (SPECT) in the young patients with vertigo presumed to have peripheral vestibular abnormalities and compared the results with cochleovestibular test results, and vertebrobasilar angiography findings. METHODS AND PATIENTS: The study was performed on 20 patients with vertigo and 17 control subjects who had performed vertebral arteriography due to another disease. The patients with vertigo presumed to be on peripheral vestibular disorder were included in the study. Systemic and otorhinolaryngological examination were carried out. Audiovestibular function was evaluated in all patients and control subjects. Brain SPECT was performed with a one-head rotating gamma camera system from 64 projections into a 64x64 matrix, using low energy and high-resolution fan beam collimators with a sampling time of 30 s. The images taken from cerebellum, temporal, parietal and occipital lobes which are supplied by a vertebrobasilar system were compared visually with the other side and asymmetry in the perfusion was searched. After cochleovestibular tests and laboratory had been completed, vertebral arteriography was performed bilaterally in all patients. Results of digital subtraction angiography (DSA) and the vestibulocochlear test were compared with images of SPECT. Data analysis was done with Yates Chi(2) and percentages of sensitivity and specificity were calculated. RESULTS: There was vestibular test and cochlear test abnormalities in eight and ten of the patients with vertigo, respectively. SPECT imaging showed hypoperfusion and decreased regional blood flow in 12 of the patients. There was statistically significant differences between the study and control groups in SPECT (P<0.05). Five patients showed abnormal findings in DSA examinations. CONCLUSION: It is believed that SPECT may be helpful in the detection of vascular pathology in the patients with vertigo.

Adult↗
PubMed2001

A seminested PCR test for simultaneous detection of two common mutations (35delG and 167delT) in the connexin-26 gene.

BACKGROUND: Several mutations described in the connexin-26 gene cause nonsyndromic autosomal recessive deafness (NARD). The prevalence of two frame-shift mutations, known as 35delG and 167delT, was relatively high in patients with NARD from different populations. METHODS AND RESULTS: A seminested PCR test has been developed for simultaneous detection of two common mutations in the connexin-26 gene. The test is based on PCR amplification of a 285-bp DNA fragment that covers both the 35delG and 167delT mutations. The latter mutation destroys a Pst I site and is easily detected by Pst I digestion of the 285-bp DNA fragment. However, the 35delG mutation does not destroy or create a restriction site. To create a site, we designed a mismatched primer that generated an EcoN I site in an 87-bp DNA fragment, but only if the 35delG mutation was present. The test was validated using five DNA samples previously characterized for the connexin-26 mutations. After validation, we screened 45 unrelated patients with NARD and 280 healthy Omani subjects for the presence or absence of the 35delG and 167delT mutations. Neither mutation was found to be present in patients or control subjects. CONCLUSION: We developed a seminested PCR test for the simultaneous detection of both common mutations in the connexin-26 gene. In our analysis of 45 patients and 280 control subjects, the 35delG and 167delT mutations were absent in both groups.

Connexin 26↗
PubMed2000

Giant polypoid tumor of the esophagus.

A patient with a giant polypoid tumor of the esophagus, measuring 22 cm in length is described in this report. The patient presented with cough attacks and respiratory distress. Diagnostic and therapeutic intervention required aggressive airway management, radiographic and endoscopic evaluation, and definitive surgical treatment. Benign esophageal tumors are rarely seen and originate from the upper third of esophagus, frequently close to the cricopharyngeus muscle. They may attain giant proportions. A variety of clinical presentations are described, the most serious being asphyxia secondary to laryngeal obstruction. We observed a giant esophageal tumor which was interpreted as angiofibromyolipoma that caused laryngeal obstruction. We present the clinical picture and histopathological findings of the tumor.

Angiofibroma↗
PubMed2000

Epidermoid cyst of the ovary: a case report.

In the ovary, epidermoid cysts are rare and their origin is controversial. This rare lesion was uniformly an incidental finding in the study of hysterectomy specimens. The patient was a 48-year-old woman. Because of multiple leiomyomas she had a total hysterectomy and bilateral salpingo-oopherectomy operation. A Epidermoid cyst was found incidentally in the right ovary on the microscopic examination.

Epidermal Cyst↗
PubMed1999

Lumbar epidural brucellar abscess causing nerve root compression.

OBJECTIVES: To evaluate the usefulness of MR sequences for the differential diagnosis of spinal brucellar abscesses which mimic lumbar disc herniation. METHODS: We analyzed six patients with brucellar abscesses who had symptoms mimicking lumbar disc herniation. The study group consisted of three women and three men who were 15-67 (mean = 37) years old. Patients were imaged in the axial and sagittal planes with a I.0-T MR scanner using a spine coil. RESULTS: The level of abscesses were accurate in 100% (six of six) of patients with MR imaging. MRI examinations revealed an extradural soft tissue mass which were iso- to hypointense compared to spinal cord on T1WI and hyperintense on T2-weighted images. By contrast study, diffuse homogeneous or slightly heterogeneous enhancements were seen. CONCLUSION: Lumbar extradural brucellar abscess can have lumbar disc disease symptoms. MRI may non-invasively and rapidly reveal the presence of spinal abscess and degree of extension to the spinal canal. Extradural brucellar abscess should be included in the differential diagnosis of radicular symptoms caused by disc herniation.

Abscess↗
PubMed1996

Plasma beta-carotene concentrations in pregnancies, newborn infants and their mothers.

Concentrations of beta-carotene were determined in maternal and fetal blood. The samples were collected from 33 mothers, their 33 newborns and 50 pregnant and 29 non-pregnant women. Beta-carotene concentrations of the non-pregnant, pregnant, newborn infant and their mothers were 140.31, 171.54, 63.57 and 175.74 micrograms/dl, respectively. There was a significant correlation (P < 0.001) between beta-carotene values of the maternal plasma and cord plasma. Mean maternal plasma beta-carotene concentration was higher (P < 0.0005) than that of the cord. These results suggest that plasma transport capacity of beta-carotene was low from mother to their fetus.

Adult↗
PubMed1992

Heredity of asthma in Saudi population.

In a cross-sectional study, the prevalence of asthma, hay fever and eczema was studied in 1150 schoolchildren attending school in Jeddah Western region of Saudi Arabia. The family histories of asthma, hay fever and eczema were examined in first degree relatives. The age range of children studied was 7-12 years, with a mean of 9.3 years (47% boys and 53% girls). A self-administered questionnaire was completed by the parents of the child to collect information concerning bronchial asthma, hay fever, and eczema in the target child and family history of respiratory allergy. A detailed family history and personal histories of asthma were available for 1035 Saudi children aged 7-12 years old. The rate of asthma and hay fever were significantly higher among siblings and offspring (cases) compared to their parents (p < 0.001). The results showed a high positive correlation between the relatives of affected children with respect to asthma and hay fever. These findings support the hypothesis that asthma and hay fever may be inherited in the Saudi population, but the mode of inheritance has yet to be determined.

Asthma↗
PubMed1990

The human cytomegalovirus immediate early enhancer-promoter is responsive to activation by the adenovirus-5 13S E1A gene.

The stimulatory effects of the 13S adenovirus E1A gene product on the human cytomegalovirus (HCMV) major immediate early (IE) enhancer were examined. Chimeric plasmids containing cloned portions of the HCMV major IE enhancer-promoter positioned upstream of the chloramphenicol acetyltransferase gene (cat) were cotransfected into HeLa cells with the plasmid p13S-wt which contained a cDNA encoding the adenovirus 13S E1A gene product. CAT expression from chimeric plasmids containing at least one copy of the HCMV 19 base pair (bp) repetitive motif was stimulated 10-fold in the presence of p13S-wt. The 19-bp motif contains a potential binding site for the cellular transcription factor ATF/CREB. Deletion analysis indicated that the ATF/CREB site was crucial for E1A-mediated stimulation. Insertion of a synthetic oligonucleotide homologous to a 19-bp motif and containing an ATF/CREB binding site into an HCMV chimera lacking ATF/CREB motifs conferred E1A responsivity on HCMV promoter-mediated CAT expression whereas insertion of a similar oligonucleotide containing a change of two bases in the sequence of the ATF/CREB site did not. Measurement of CAT-specific RNA verified the results of the CAT enzyme experiments. The ATF/CREB motif may be a target for stimulation of HCMV gene expression through either viral or cellular transcription factors.

Activating Transcription Factors↗
PubMed1989

Direct detection of human cytomegalovirus in urine specimens from renal transplant patients following polymerase chain reaction amplification.

A polymerase chain reaction (PCR) assay was used to amplify human cytomegalovirus (HCMV) directly from urine specimens taken from renal transplant patients. In serial urine samples from patients who had at least one specimen positive for HCMV; the PCR assay consistently detected the presence of HCMV DNA sequences, whereas virus detection by other tests such as enzyme-linked immunosorbent assay (ELISA), nonradioactive DNA hybridization assay, and virus isolation were variable. Of 37 specimens positive by PCR, 36 were positive by either ELISA, hybridization assay, or virus isolation. Infectious virus was detected in 13 of the 37 PCR-positive urines. HCMV DNA was detected by PCR in all samples that were positive for HCMV by either hybridization assay or virus isolation. The viral genome copy number was determined by PCR assay for several urine samples that were positive by virus isolation but negative for HCMV by ELISA or hybridization assay. Viral genome copy number estimates indicated the presence of HCMV at very low levels in these urines verifying the fidelity of the virus isolation procedures. The consistency of the PCR assay makes it an ideal method for detection of infection and monitoring antiviral drug therapy in patients infected with HCMV.

Antigens, Viral↗
PubMed1989

Polymerase chain reaction assay for detection of human cytomegalovirus.

Direct detection of human cytomegalovirus (HCMV) from clinical specimens was examined by using the polymerase chain reaction (PCR) for amplifying HCMV DNA. The efficiency of the amplification reaction was examined by using three different buffers and concentrations of deoxynucleotide triphosphates. The PCR assay was most efficient with a reaction mixture containing 17 mM ammonium sulfate, 67 mM Tris hydrochloride (pH 8.5), 7 mM MgCl2, 10 mM 2-mercaptoethanol, 170 micrograms of bovine serum albumin per ml, and each deoxynucleotide triphosphate at a final concentration of 1.5 mM. After 35 cycles of amplification, 0.15 fg of a plasmid containing the cloned target gene (corresponding to approximately six gene copies) was detected. The PCR assay correctly identified all of 24 clinical isolates of HCMV. Virus in urine specimens could be disrupted by heating at 93 degrees C for 30 min. The viral DNA was amplified directly from 5 microliters of preheated urine, with no further treatment before amplification. We tested the PCR assay on urine specimens from patients who had undergone renal transplantation that had been screened for the presence of HCMV by enzyme-linked immunosorbent assay, hybridization assay, and direct virus isolation. Specimens that were positive by one or more of these assays were screened by PCR. HCMV was consistently detected by PCR in all specimens that were positive by at least one other test. No cross-reactivity to other herpesviruses or MRC-5 cellular DNA was observed.

Cytomegalovirus↗
PubMed1988

Translation of globin RNA spliced in vitro.

Pre-mRNA (precursor mRNA) enriched for globin-gene transcription products was prepared from murine erythroleukaemia cells induced to differentiate with dimethyl sulphoxide. The pre-mRNA was prepared from nuclear RNA by oligo(dT)-cellulose chromatography followed by sucrose-gradient centrifugation. The pre-mRNA thus obtained was utilized as the substrate for a splicing assay based on sequential splicing and translation reactions. Small nuclear ribonucleoprotein particles, which were shown to inhibit translation, were removed by an intermediate high-speed centrifugation step. The assay developed is based on a three-step procedure: (1) incubation of pre-mRNA with HeLa-cell nuclear extract in the presence of ATP; (2) incorporation of 3H-labelled amino acid into proteins by wheat-germ extract by using RNA from step 1; and (3) immunoprecipitation of globin chains with rabbit anti-(mouse globin) antibody. No incorporation of label into immune complexes was observed in the absence of HeLa-cell extract or ATP. Preincubation with these components was unnecessary for the incorporation of label into immune complexes when mature cytoplasmic RNA was used as a template for protein synthesis. The assay was further validated by fluorography after polyacrylamide-gel electrophoresis, when the only band detectable corresponded to globin chains. These results demonstrate, for the first time, translational activity of transcripts spliced in vitro. The current assay can be utilized with a few micrograms of pre-mRNA and may have potential for further characterization of the splicing system.

Cell Line↗
PubMed1988

A precaution when preparing very large plasmids by alkaline lysis procedure.

The extractabilities of plasmids of different sizes by the sodium lauryl sulfate (SDS)-alkali procedure were compared using either sodium acetate or potassium acetate buffer as the neutralizing agent. There was a selective loss of large plasmids (above 100 kb) when the potassium salt was used. When N-lauryl sarcosine instead of SDS was used as the detergent, no loss of large plasmids occurred in the presence of potassium salt. A comparison of the kinetics of precipitate formation with sodium acetate and potassium acetate indicated that the rate and the amount of lauryl sulfate precipitated were lower with the sodium salt. It is suggested that faster precipitation of lauryl sulfate with potassium acetate leads to trapping of large denatured plasmids that cannot renature as fast as the small ones.

Acetates↗
PubMed1982

Nucleotide sequence of wheat germ cytoplasmic initiator methionine transfer ribonucleic acid.

The primary sequence of wheat germ initiator tRNA has been determined using in vitro labelling techniques. The sequence is: pAUCAGAGUm1Gm2GCGCAG CGGAAGCGUm2GG psi GGGCCCAUt6AACCCACAGm7GDm5Cm5CCAGGA psi CGm1AAACCUG*GCUCUGAUACCAOH. As in other eukaryotic initiator tRNAs, the sequence -T psi CG(A)- present in loop IV of virtually all tRNA active in protein synthesis is absent and is replaced by -A psi CG-. The base pair G2:C71 present in all other initiator tRNAs recognized by E. coli Met-tRNA transformylase is absent and is replaced by U2:A71. Since wheat germ initiator tRNA is not formylated by E. coli Met-tRNA transformylase this implies a possible role of the G2:C71 base pair present in other initiator tRNAs in formylation of initiator tRNA species.

Base Sequence↗
PubMed1982

A transposable element from Halobacterium halobium which inactivates the bacteriorhodopsin gene.

We describe the characterization of a transposable element from an archaebacterium. The bacteriorhodopsin genes from the wild-type and two mutant Halobacterium halobium strains have been cloned as BamHI fragments in pBR322. The cloned DNA fragments from the two mutants both contain a 1.1-kilobase-pair insertion sequence (ISH1) near the NH2 terminus of the bacteriorhodopsin coding sequence. ISH1 is present in the two mutants in an identical palindromic site but in opposite orientations. The complete sequence of ISH1 has been determined; it is 1,118 nucleotides long, it has 8-base-pair interrupted inverted repeats at the ends, and it duplicates an 8-base-pair (A-G-T-T-A-T-T-G) target sequence upon insertion. As for most eukaryotic and some prokaryotic transposable elements, the sequence of the ISH1 begins with T-G and ends in C-A. ISH1 contains an open reading frame 810 nucleotides long and codes for an RNA approximately 900 nucleotides long. The copy number of ISH1 ranges from one to five or more in different H. halobium strains. In at least one of the strains, one copy of ISH1 is present also on a plasmid DNA.

Bacteriorhodopsins↗
PubMed1979

Nucleotide sequence of three isoaccepting lysine tRNAs from rabbit liver and SV40-transformed mouse fibroblasts.

The lysine isoacceptor tRNAs differ in two aspects from the majority of the other mammalian tRNA species: they do not contain ribosylthymine (T) in loop IV, and a 'new' lysine tRNA, which is practically absent in non-dividing tissue, appears at elevated levels in proliferating cells. We have therefore purified the three major isoaccepting lysine tRNAs from rabbit liver and the 'new' lysine tRNA isolated from SV40-transformed mouse fibroblasts, and determined their nucleotide sequences. Our basic findings are as follows. a) The three major lysine tRNAs (species 1, 2 and 3) from rabbit liver contain 2'-O-methylribosylthymine (Tm) in place of T. tRNA1Lys and tRNA2Lys differ only by a single base pair in the middle of the anticodon stem; the anticodon sequence C-U-U is followed by N-threonyl-adenosine (t6A). TRNA3Lys has the anticodon S-U-U and contains two highly modified thionucleosides, S (shown to be 2-thio-5-carboxymethyl-uridine methyl ester) and a further modified derivative of t6 A (2-methyl-thio-N6-threonyl-adenosine) on the 3' side of the anticodon. tRNA3Lys differs in 14 and 16 positions, respectively, from the other two isoacceptors. b) Protein synthesis in vitro, using synthetic polynucleotides of defined sequence, showed that tRNA2Lys with anticodon C-U-U recognized A-A-G only, whereas tRNA3Lys, which contains thio-nucleotides in and next to the anticodon, decodes both lysine codons A-A-G and A-A-A, but with a preference for A-A-A. In a globin-mRNA-translating cell-free system from ascites cells, both lysine tRNAs donated lysine into globin. The rate and extent of lysine incorporation, however, was higher with tRNA2Lys than with tRNA3Lys, in agreement with the fact that alpha-globin and beta-globin mRNAs contain more A-A-G than A-A-A- codons for lysine. c) A comparison of the nucleotide sequences of lysine tRNA species 1, 2 and 3 from rabbit liver, with that of the 'new' tRNA4Lys from transformed and rapidly dividing cells showed that this tRNA is not the product of a new gene or group of genes, but is an undermodified tRNA derived exclusively from tRNA2Lys. Of the two dihydrouridines present in tRNA2Lys, one is found as U in tRNA4Lys; the purine next to the anticodon is as yet unidentified but is known not be t6 A. In addition we have found U, T and psi besides Tm as the first nucleoside in loop IV.

Animals↗