Biomedical subjects

S Aksoy

Publications and source records attributed to S Aksoy.

At least 37 records · Page 2Linked to original sources

PubMed2001

Characterization of genes expressed in the salivary glands of the tsetse fly, Glossina morsitans morsitans.

Salivary gland products of haematophogous insects including tsetse flies (Diptera: Glossinidia) are involved in antihaemostasis to allow for efficient blood feeding. In addition, salivary products of tsetse are thought to indirectly support the metacyclogenesis and eventual transmission of the African trypanosome protozoan parasites to their mammalian hosts. We have previously characterized the major anticoagulant, Tsetse Thrombin Inhibitor (TTI), from salivary extracts, and described molecular aspects of its cDNA from a Glossina morsitans morsitans salivary gland cDNA library. In addition, a family of two related genes with growth factor and adenosine-deaminase motifs (TSGF-1 and TSGF-2) have also been described. Here, we report on the molecular aspects of three different cDNAs and their putative products expressed in salivary glands: cDNAs TAg5, Tsal1 and Tsal2. The full-length transcript encoded by Tsetse Antigen 5 (TAg5) cDNA is 926 bp excluding the poly(A) stretch, and has an open reading frame of 259 amino acids that can encode for a protein of 28 925 Da. The putative product of TAg5 shows extensive similarities to cDNAs characterized from Drosophila (Agr and Agr2) and sandfly Lutzomyia (LuLoAG5). The cDNAs Tsal1 and Tsal2 are predicted to encode for mature proteins of 45 612 Da (399 amino acids) and 43 930 Da (389 amino acids), respectively, and their putative products exhibit over 42% identity to one another. The N terminus of each putative protein contains a hydrophobic region with signal peptide characteristics indicating that they may be secretory in nature. Transcripts specific for TAg5 and Tsal2 genes can be detected in all developmental stages of tsetse while Tsal1 expression is limited to adult and larval stages. A reverse transcription polymerase chain reaction based amplification approach indicates that TAg5 transcipts can be detected from proventriculus and midgut tissues of the fly in addition to salivary glands, while Tsal1 and Tsal2 expression is restricted to salivary gland and proventriculus. The salivary glands of adult males are found to express higher levels of TAg5 and Tsal2 in comparison to females while no significant sex-based difference is observed for Tsal1 expression. The expression of these cDNAs in different tsetse species (G. m. morsitans, Glossina austeni and Glossina fuscipes) shows wide variations.

Amino Acid Sequence↗

PubMed2001

Blastocyst transfer following intracytoplasmic injection of ejaculated, epididymal or testicular spermatozoa.

Recent studies indicate a strong paternal influence on embryo development and progression of the embryo to the blastocyst stage. The aim of this study was to compare, during extended culture, the in-vitro development of embryos resulting from intracytoplasmic sperm injection (ICSI) of ejaculated spermatozoa (group 1, n = 347), epididymal (group 2, n = 22) or testicular (group 3, n = 18) spermatozoa from obstructive azoospermic and testicular spermatozoa from non-obstructive azoospermic (group 4, n = 31) subjects. Fertilization and blastocyst formation rates were significantly lower in group 4 (P < 0.05). The incidence of expanded and hatching blastocysts was significantly lower in group 4 (P < 0.05). Overall in 93.2% ejaculate ICSI cycles, blastocysts were transferred on day 5. This was significantly higher than the 62% day 5 transfers in the non-obstructive azoospermic group (P < 0.05). Implantation rate per embryo was significantly higher in the ejaculate ICSI group compared with the other groups (P < 0.05). Clinical pregnancy per transfer was similar between groups; however, significantly fewer multiple pregnancies were encountered in the non-obstructive azoospermic group (P < 0.01). In conclusion, the source of the spermatozoa, most likely to be indicative of the severity of spermatogenic disorder, affects the rate of blastocyst formation and blastocyst implantation. Spermatozoa from non-obstructive azoospermic subjects, when utilized for ICSI, result in embryos that progress to the blastocyst stage at a lower and slower rate and implant less efficiently.

Adult↗

PubMed2001

The effect of pronuclear morphology on embryo quality parameters and blastocyst transfer outcome.

BACKGROUND: Embryo quality may be accurately assessed as early as the pronuclear zygote phase, as shown in recent studies. However, it is not known whether good quality zygotes are destined to become good quality cleavage stage embryos and blastocysts. METHODS: In this retrospective study, 86 intracytoplasmic sperm injection-embryo transfer cycles were studied where each available embryo was scored from the zygote until the blastocyst stage. Embryonic normality parameters such as pronuclear pattern, early cleavage, cleavage stage embryo grade, the presence of embryos with > or =8 cells on day 3 and blastocyst quality were recorded. Embryo transfer was undertaken at the blastocyst stage and the outcome was studied according to the pronuclear pattern exhibited by the zygotes. RESULTS: Embryos that showed an ideal pronuclear pattern (0 PN pattern) cleaved earlier and faster and resulted in better quality cleavage stage embryos and blastocysts. The incidence of blastocyst formation was 72% in zygotes showing a 0 PN pattern, compared with 12.7% in zygotes with double pronuclear abnormality. Higher implantation and pregnancy rates were obtained when at least one blastocyst derived from a 0 PN pattern zygote was included in the set of embryos to be transferred. CONCLUSIONS: Our results indicate that the pronuclear pattern of the zygote is closely related to blastocyst formation and quality. Blastocysts derived from 0 PN zygotes have a higher potential for implantation.

Blastocyst↗

PubMed2001

A critical approach to the current understanding of Islamic scholars on using cadaver organs without prior permission.

Chronic organ diseases and the increasing demand for organ transplantation have become an important health care problem within the last few decades. Campaigns and regulations to encourage people to donate organs after death have not met with much success. This article discusses the subject from an Islamic perspective. It beings with some basic information on how Muslims reach legal rulings on a particular issue, and goes on to debate contemporary thinking among Islamic scholars on the ethical-legal issues of organ donation and organ transplantation. It is shown that there are two groups of scholars, one allowing organ donation and organ transplantation, the other refusing it in any circumstances. Both groups agree that is is fundamentally wrong to harvest organs from cadavers without prior permission of the deceased or the relatives. This dogma is re-examined, and it is argued that, under the rule of necessity and the imperative to preserve life, there is enough moral and theological ground to allow the state to harvest organs from the deceased without prior permission.

Brain Death↗

PubMed2001

Genome size determination and coding capacity of Sodalis glossinidius, an enteric symbiont of tsetse flies, as revealed by hybridization to Escherichia coli gene arrays.

Recent molecular characterization of various microbial genomes has revealed differences in genome size and coding capacity between obligate symbionts and intracellular pathogens versus free-living organisms. Multiple symbiotic microorganisms have evolved with tsetse fly, the vector of African trypanosomes, over long evolutionary times. Although these symbionts are indispensable for tsetse fecundity, the biochemical and molecular basis of their functional significance is unknown. Here, we report on the genomic aspects of the secondary symbiont Sodalis glossinidius. The genome size of Sodalis is approximately 2 Mb. Its DNA is subject to extensive methylation and based on some of its conserved gene sequences has an A+T content of only 45%, compared to the typically AT-rich genomes of endosymbionts. Sodalis also harbors an extrachromosomal plasmid about 134 kb in size. We used a novel approach to gain insight into Sodalis genomic contents, i.e., hybridizing its DNA to macroarrays developed for Escherichia coli, a closely related enteric bacterium. In this analysis we detected 1,800 orthologous genes, corresponding to about 85% of the Sodalis genome. The Sodalis genome has apparently retained its genes for DNA replication, transcription, translation, transport, and the biosynthesis of amino acids, nucleic acids, vitamins, and cofactors. However, many genes involved in energy metabolism and carbon compound assimilation are apparently missing, which may indicate an adaptation to the energy sources available in the only nutrient of the tsetse host, blood. We present gene arrays as a rapid tool for comparative genomics in the absence of whole genome sequence to advance our understanding of closely related bacteria.

Animals↗

PubMed2001

Microsatellite polymorphism in tsetse flies (Diptera: Glossinidae).

In sub-Saharan Africa, tsetse flies are the vectors of trypanosomes, the causative agents of sleeping sickness in humans and nagana in animals. Certain wild populations of the palpalis group exhibit intraspecific variation and are suspect of manifest differences in vectorial capacity. The current study reports the identification of 13 polymorphic microsatellite loci from Glossina palpalis palpalis Robinean-Desvoidy. The majority of these markers amplify corresponding loci from the related species C. p. gambiensis Vanderplank, G. f. fuscipes Newstead, and G. tachinoides Westwood. Only seven of 13 loci were amplified from G. austeni Newstead. Genetic variability was estimated in one field population of G. p. gambiensis. These results confirmed that microsatellite markers may be used to examine the subpopulation structure of tsetse flies.

Alleles↗

PubMed2001

[Ancient Indian and Chinese medical oaths and the comparison of their medical rules].

The art of medicine has existed on earth since the existence of mankind. Although the traditions and practices may vary, the mere intention has been to help people remain healthy and restore their health when they get sick. Since health is man's most important fortune, the medical profession has always been open to abuse or misuse. To prevent this, it came to be a tradition to bound health care professionals with oaths and codes. This article examines medical oaths and codes in two different Eastern traditions, namely China and India. Two different medical oaths from two major ancient Indian medical books, Charaka Samhita and Susuruta will be addressed and elaborated. They will be compared and contrasted with each other and their commons and differences from the other medical oaths will be examined. Chinese medical codes, one from the 7th and the other from the 17th century are reviewed in the article. It has appeared from the discussion that although there are some 'unchangeables' in the codes and oaths, like the reference to some sacred or transcendental being or commitment to show respect to the teachers, there are differences due to the time and place. It is also interesting to note how medical practice and its values are influenced by the respective society.

China↗

PubMed2000

A family of genes with growth factor and adenosine deaminase similarity are preferentially expressed in the salivary glands of Glossina m. morsitans.

A cDNA library constructed from salivary glands of tsetse fly, Glossina morsitans morsitans (Diptera: Glossinidae), was differentially screened, and two related full-length cDNAs were molecularly characterized: tsetse salivary growth factor, TSGF-1 and TSGF-2. The cDNAs encode for open reading frames (ORFs) of 494 and 506aa, respectively, and display an overall 45% amino acid identity and 61% similarity to one another. Both genes are preferentially expressed in the salivary glands of male and female adult flies. In addition to salivary glands, both transcripts can be detected from the gut tissue. Only transcripts specific for TSGF-2 are detected in ovary and testes tissues of adults as well as in puparia, while neither gene is expressed during the larval developmental stages. The N-terminal region of both putative proteins contains a hydrophobic sequence with secretory signal peptide characteristics, and analysis of proteins in saliva by Western blot indicates that both are secreted. Western blot analysis indicates that TSGF-1 is synthesized at significantly higher levels than TSGF-2. The deduced protein sequences of both cDNAs display extensive similarities to two other proteins: insect derived growth factor (IDGF) characterized from Sarcophaga peregrina with growth-factor activity, and atrial gland specific antigen (AGSA or MDSF) characterized from Apylasia californica. In addition to growth factor similarity, all four related proteins share the evolutionarily conserved amino acid residues associated with the enzymatic deamination of adenosine, which is shown here to be present in salivary gland extracts of tsetse. While both genes are present and expressed in G. m. morsitans and G. p. palpalis, only TSGF-1 is present in G. austeni. We present the molecular characteristics of the cDNAs, their genomic arrangement and their regulation of expression in different fly tissues and species. We discuss the potential role of these proteins in hemostatis and in African trypanosome transmission by different species of tsetse.

Adenosine Deaminase↗

PubMed2000

Abnormal development of Purkinje cells and lymphocytes in Atm mutant mice.

Motor incoordination, immune deficiencies, and an increased risk of cancer are the characteristic features of the hereditary disease ataxia-telangiectasia (A-T), which is caused by mutations in the ATM gene. Through gene targeting, we have generated a line of Atm mutant mice, Atm(y/y) mice. In contrast to other Atm mutant mice, Atm(y/y) mice show a lower incidence of thymic lymphoma and survive beyond a few months of age. Atm(y/y) mice exhibit deficits in motor learning indicative of cerebellar dysfunction. Even though we found no gross cerebellar degeneration in older Atm(y/y) animals, ectopic and abnormally differentiated Purkinje cells were apparent in mutant mice of all ages. These findings establish that some neuropathological abnormalities seen in A-T patients also are present in Atm mutant mice. In addition, we report a previously unrecognized effect of Atm deficiency on development or maintenance of CD4(+)8(+) thymocytes. We discuss these findings in the context of the hypothesis that abnormal development of Purkinje cells and lymphocytes contributes to the pathogenesis of A-T.

Animals↗

PubMed2000

Blastocyst quality affects the success of blastocyst-stage embryo transfer.

OBJECTIVE: To determine the relationship between blastocyst quality and the results of embryo transfer at the blastocyst stage. DESIGN: Retrospective case analysis. SETTING: Tertiary care private hospital IVF center. PATIENT(S): A total of 350 blastocyst-stage embryo transfer cycles. INTERVENTION(S): In vitro culture to the blastocyst stage was undertaken in 350 ICSI cycles where four or more cleavage-stage embryos were available on day 3. MAIN OUTCOME MEASURE(S): Relationship between blastocyst quality and implantation and clinical and multiple pregnancy rates. RESULT(S): Transfer of at least one grade 1 or grade 2 blastocyst or one hatching blastocyst was associated with very high implantation and pregnancy rates. However, transfer of grade 3 blastocysts yielded very low implantation and pregnancy rates. CONCLUSION(S): There appears to be a strong correlation between blastocyst quality and success of blastocyst transfer.

Blastocyst↗

PubMed2000

Tsetse--A haven for microorganisms.

Arthropods are involved in the transmission of parasitic and viral agents that cause devastating diseases in animals and plants. Effective control strategies for many of these diseases still rely on the elimination or reduction of vector insect populations. In addition to these pathogenic organisms, arthropods are rich in microbes that are symbiotic in their associations and are often necessary for the fecundity and viability of their hosts. Because the viability of the host often depends on these obligate symbionts, and because these organisms often live in close proximity to disease-causing pathogens, they have been of interest to applied biologists as a potential means to genetically manipulate populations of pest species. As knowledge on these symbiotic associations accumulates from distantly related insect taxa, conserved mechanisms for their transmission and evolutionary histories are beginning to emerge. Here, Serap Aksoy summarizes current knowledge on the functional and evolutionary biology of the multiple symbionts harbored in the medically and agriculturally important insect group, tsetse, and their potential role in the control of trypanosomiasis.

Animals↗

PubMed2000

Tissue distribution and prevalence of Wolbachia infections in tsetse flies, Glossina spp.

Tsetse flies Glossina spp. (Diptera: Glossinidae) harbor three different symbiotic microorganisms, one being an intracellular Rickettsia of the genus Wolbachia. This bacterium infects a wide range of arthropods, where it causes a variety of reproductive abnormalities, one of which is termed cytoplasmic incompatibility (CI) that, when expressed, results in embryonic death due to disruptions in fertilization events. We report here that in colonized flies, Wolbachia infections can be detected in 100% of sampled individuals, while infections vary significantly in field populations. Based on Wolbachia Surface Protein (wsp) gene sequence analysis, the infections associated with different fly species are all unique within the A group of the Wolbachia pipientis clade. In addition to being present in germ-line tissues, Wolbachia infections have been found in somatic tissues of several insects. Using a Wolbachia-specific PCR-based assay, the tissue tropism of infections in Glossina morsitans morsitans Westwood, Glossina brevipalpis Newstead and Glossina austeni Newstead were analysed. While infections in G. m. morsitans and G. brevipalpis were limited to reproductive tissues, in G. austeni, Wolbachia could be detected in various somatic tissues.

Animals↗

PubMed2000

In-vitro spermatogenesis resumption in men with maturation arrest: relationship with in-vivo blocking stage and serum FSH.

We have shown previously that germ cells recovered from some men with maturation arrest can resume spermatogenesis in vitro and give rise to late elongated spermatids. This study relates the ability of germ cells to differentiate in vitro to the stage at which spermatogenesis is blocked in vivo and to the patient's serum FSH concentration. The presence of germ cells at different stages of spermatogenesis was assessed, before and after culture, by classical cytology, by fluorescence in-situ hybridization and by immunocytochemistry with a germline-specific marker. The proportion of cases of maturation arrest at the primary spermatocyte, secondary spermatocyte and spermatid stage in which in-vitro resumption of meiosis was achieved was 24.3% (9/37), 100% (3/3) and 51.1% (23/45) respectively. Serum FSH concentrations were higher than normal in most cases. However, lower values were measured in patients in whom in-vitro spermatogenesis was achieved compared with those in whom no progression was detected. These data show that, under the conditions of this study, germ cells from men with very high serum FSH concentrations (>20 IU/l) are less likely to resume spermatogenesis in vitro than those coming from men with only moderate increase (10-20 IU/l).

Adult↗

PubMed2000

Progression to the blastocyst stage of embryos derived from testicular round spermatids.

Progression to the blastocyst stage of embryos derived from testicular round spermatids in men with non-obstructive azoospermia was studied. A total of 56 men were studied in whom partial spermatogenesis failure had occurred where only very few spermatozoa (fewer than the number of oocytes retrieved) were extracted from multiple testicular biopsy specimens. Oocytes remaining after intracytoplasmic injection of testicular spermatozoa (group 1) were injected with round spermatids (ROSI, group 2). Only embryos derived from group 1 were transferred. Remaining embryos were observed under culture for 8 days and their progression to the blastocyst stage was recorded. Of the 546 oocytes injected with testicular spermatozoa, 404 (73.9%) showed evidence of 2-pronuclear (2PN) fertilization. Injection of testicular round spermatids resulted in 2PN fertilization rate of 50% (P < 0.05). Using a four-point grading system, 53% of the good quality embryos (grade 1 or 2) in group 1 reached the blastocyst stage compared with 25% in group 2 (P < 0.05). The rate of progression to the blastocyst stage of grade 3 and grade 4 embryos was 46 and 8.5% in the two groups respectively (P < 0.05). Using a different three-point grading system for the blastocysts, 75.3% of the blastocysts in group 1 were either grade 1 or grade 2 and 24.7% were grade 3. However, in group 2 all blastocysts were grade 3. All embryos observed in group 1 reached the blastocyst stage by day 5 or 6 compared with 25% of the embryos reaching the blastocyst stage by this time in group 2. While 31.2% of the blastocysts in group 1 showed evidence of spontaneous hatching in vitro, none of the blastocysts in group 2 hatched. In conclusion, progression to the blastocyst stage occurred at a much lower and slower rate in embryos derived from testicular round spermatids. Furthermore, all blastocysts resulting from ROSI were of poor quality and none showed spontaneous hatching. These results may explain the dismal outcome associated with ROSI.

Blastocyst↗

PubMed2000

Outcome of testicular sperm retrieval procedures in non-obstructive azoospermia: percutaneous aspiration versus open biopsy.

The aim of this study was to evaluate whether the extraction of testicular spermatozoa with percutaneous versus open biopsy has an effect on the treatment outcome with intracytoplasmic sperm injection (ICSI) in men with non-obstructive azoospermia. Regardless of testicular size, follicle stimulating hormone concentration, and previous biopsy result, percutaneous testicular sperm aspiration (PTSA) using a 21-gauge butterfly needle was attempted first and if this failed testicular sperm extraction (TESE) was performed. In 63 men spermatozoa were found with PTSA whereas in 228 men TESE had to be undertaken. More men in the PTSA group had previously been diagnosed with hypospermatogenesis (82 versus 50%). Compared with the PTSA group, more men in the TESE group had germ cell aplasia (27 versus 10%) or maturation arrest (22 versus 8%). There was no difference between the groups regarding mean age of men and their partners, duration of stimulation, oestradiol concentration on the day of human chorionic gonadotrophin, number of oocytes retrieved, fertilization rate, and embryo quality between the two groups. The number of embryos transferred (4.38 versus 3.90) was significantly higher in the PTSA group (P < 0.05), reflecting the increased number of embryos available for transfer. Implantation rate per embryo was 20.7% in the PTSA and 13.3% in the TESE group (P < 0.05). Clinical pregnancy rates were 46 and 29% in the PTSA and TESE groups respectively (P < 0.05). Clinical abortion rates were similar (21.2 versus 24%). It is concluded that in men with non-obstructive azoospermia, easier sperm retrieval, which is most likely indicative of a more favourable histopathology, is associated with higher implantation rates per embryo.

Adult↗

PubMed2000

Comparing two embryo transfer catheters. Use of a trial transfer to determine the catheter applied.

OBJECTIVE: To analyze the performance of two different embryo transfer catheters (Wallace and Frydman) in an in vitro fertilization (IVF)-intracytoplasmic sperm injection (ICSI) program. STUDY DESIGN: Four hundred twenty-eight IVF or ICSI embryo transfer cycles were analyzed. A trial transfer was performed before the initiation of controlled ovarian hyperstimulation to determine the choice of embryo transfer catheter, Wallace or Frydman. Actual transfer was undertaken with the catheter chosen from the trial transfer. RESULTS: During actual embryo transfer, 214 (93.5%) of the intended 229 Wallace transfers were successful, and in 15 transfers the Frydman catheter was used. Of the intended 199 Frydman transfers, all were successful. Clinical pregnancy rate, implantation rate per embryo and ectopic pregnancy rate per transfer for the Wallace catheter were 41.6%, 16% and 0.9%, respectively. Respective rates for the Frydman catheter were 36.0%, 14.4% and 0.9% (P > .05 for all variables). Trial catheterization prevented most of the unanticipated procedural difficulties during the actual transfer. CONCLUSION: Both Wallace and Frydman catheters performed similarly, although there was a slight but nonsignificant increase in clinical pregnancy rates with the Wallace catheter.

Adult↗

PubMed2000

Can the "quality of life" be used as a criterion in health care services?

Because the resources in health care services are limited, different criteria have been used to choose patients for treatment or for non-treatment. The 'Quality of Life' criterion is the one most commonly used in different parts of the world. However the usefulness and necessity of quality of life judgements in health services has always been controversial. This article discusses the 'Quality of Life' criterion from different perspectives. It appears from the discussion that it is not easy to define 'Quality of Life' and the difficulty originates from the relativity of the concept. The article also examines the QALY (Quality Adjusted Life Year), and concludes that it not only involves ageism and sexism but also injustice and unfair discrimination. The article finally argues that it is not possible to measure the quality of life of an individual either accurately or reliably. Therefore it cannot be used as a criterion in health care services.

Euthanasia, Passive↗

PubMed1999

Mouse phosphoinositide 3-kinase p110alpha gene: cloning, structural organization, and localization to chromosome 3 band B.

Phosphoinositide 3-Kinases (PI3-Kinases) are a family of dual specificity enzymes with a unique lipid kinase activity toward the D-3 position of the inositol ring of phosphoinositides and a less well characterized serine/threonine protein kinase activity. Class IA PI3-Kinases comprise a 110-120 kDa catalytic subunit (usually termed p110) and an 85 kDa or 50 to 55 kDa regulatory subunit (often called p85). cDNAs for three mammalian Class IA PI3-Kinase catalytic subunits designated p110alpha, p110beta, and p110delta have been cloned from several species. A YAC clone for the human p110alpha gene has also been cloned and mapped to chromosome 3q26.3. However, structural organization for any of the PI3-Kinase p110alpha genes has not been reported. Here, we report the cloning, structural organization, and chromosomal localization of the mouse PI3-Kinase p110alpha gene. The translated portion of the mouse p110alpha gene is encoded by 19 exons that span at least 24 kb. Dual color fluorescence in situ hybridization (FISH) was performed to determine the chromosomal localization of the mouse PI3-Kinase p110alpha gene. FISH results and DAPI banding demonstrated localization of the p110alpha gene to band B on mouse chromosome 3, a region syntenic with human chromosome 3q26.3.

Animals↗