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Biomedical subjects

S Bakalis

Publications and source records attributed to S Bakalis.

7 recordsLinked to original sources
PubMed2002

Outcome of antenatally diagnosed talipes equinovarus in an unselected obstetric population.

OBJECTIVE: To investigate the natural history and outcome of fetal talipes diagnosed by routine ultrasound scanning at 18-23 weeks' gestation. PATIENTS AND METHODS: This was a retrospective study of 103 228 pregnancies undergoing routine ultrasound scanning at 18-23 weeks' gestation. A computer search was made to identify all cases of fetal talipes and the records of these patients were examined to determine the incidence of other defects and pregnancy outcome. RESULTS: The incidence of fetal talipes following routine ultrasound examination was 0.10% (107/103 228) and was bilateral in 64 (59.8%) and unilateral in 43 (40.2%) cases. In 52 (48.6%) cases, talipes was of complex etiology, as it was associated with other defects, while, in 55 (51.4%) cases, it was classified as idiopathic. In 19% of cases, an initial diagnosis of idiopathic talipes was changed to complex, because of the subsequent development of associated features. Perinatal death and long-term neurodevelopmental or musculoskeletal problems were significantly more common when the talipes was complex rather than idiopathic (odds ratio, 150; 95% confidence interval, 34-665). Adverse outcomes were also seen more frequently with bilateral compared to unilateral talipes (odds ratio, 3.44; 95% confidence interval, 1.50-7.90). CONCLUSION: The outcome of antenatally detected talipes is mainly dependent on the presence or absence of other defects. A significant proportion of cases, thought to be idiopathic at presentation, will develop associated complex features when reassessed on subsequent scans or postnatally.

Clubfoot↗
PubMed2001

Outcome of pregnancy in chromosomally normal fetuses with increased nuchal translucency in the first trimester.

OBJECTIVES: To study the outcome of chromosomally normal pregnancies with increased nuchal translucency at the 10-14-week scan. DESIGN: Retrospective study of 1320 chromosomally normal singleton pregnancies with nuchal translucency of > or = 3.5 mm. In addition to fetal karyotyping these patients were managed with follow-up scans at 14-16 and 20-22 weeks, specialist fetal echocardiography and in selected cases by infection screening and further genetic testing. RESULTS: In the 1320 pregnancies there were 68 (5.15%) spontaneous abortions or intrauterine deaths, 18 (1.36%) neonatal and infant deaths and 154 (11.67%) terminations of pregnancy. In the 1080 (81.82%) survivors, 60 (5.56%) had abnormalities requiring medical or surgical treatment or leading to mental handicap. The chance of a livebirth with no defects in the group with nuchal translucency of 3.5-4.4 mm was 86%, for those with translucency of 4.5-5.4 mm it was 77%, for those with translucency of 5.5-6.4 mm it was 67%, and for those with translucency of > or = 6.5 mm it was 31%. CONCLUSIONS: Increased fetal nuchal translucency is associated with chromosomal abnormalities, many fetal defects and genetic syndromes. In the majority of cases a series of antenatal investigations, including fetal karyotyping, detailed scans, fetal echocardiography, as well as genetic testing and infection screening, that can be completed by 20 weeks of gestation would distinguish between the pregnancies destined to result in adverse outcome and those leading to the delivery of infants without major defects.

Female↗
PubMed1994

Tau confers drug stability but not cold stability to microtubules in living cells.

We previously defined two classes of microtubule polymer in the axons of cultured sympathetic neurons that differ in their sensitivity to nocodazole by roughly 35-fold (Baas and Black (1990) J. Cell Biol. 111, 495-509). Here we demonstrate that virtually all of the microtubule polymer in these axons, including the drug-labile polymer, is stable to cold. What factors account for the unique stability properties of axonal microtubules? In the present study, we have focused on the role of tau, a microtubule-associated protein that is highly enriched in the axon, in determining the stability of microtubules to nocodazole and/or cold in living cells. We used a baculovirus vector to express very high levels of tau in insect ovarian Sf9 cells. The cells respond by extending processes that contain dense bundles of microtubules (Knops et al. (1991) J. Cell Biol. 114, 725-734). Cells induced to express tau were treated with either cold or 2 micrograms/ml nocodazole for times ranging from 5 minutes to 6 hours. The results with each treatment were very different from one another. Virtually all of the polymer was depolymerized within the first 30 minutes in cold, while little or no microtubule depolymerization was detected even after 6 hours in nocodazole. Based on these results, we conclude that tau is almost certainly a factor in conferring drug stability to axonal microtubules, but that factors other than or in addition to tau are required to confer cold stability.

Animals↗
PubMed1992

Phosphorylated baculovirus p10 is a heat-stable microtubule-associated protein associated with process formation in Sf9 cells.

Insect ovarian Sf9 cells extend processes with complex morphologies when infected with a recombinant baculovirus encoding the catalytic subunit of protein kinase A. Within the shafts of the processes are abundant microtubules, which, in contrast to those in Sf9 cells expressing the microtubule-associated protein tau, are generally not organized into parallel bundles. During infection the late viral polypeptide p10 becomes phosphorylated by the protein kinase A catalytic subunit at its penultimate residue, Ser92. The expression or phosphorylation of other major host cell or viral polypeptides does not change, compared with polypeptides from a wild-type viral infection. Once phosphorylated, p10 associates with microtubules in the infected cells and may thereby play a role in process formation.

Amino Acid Sequence↗
PubMed1989

Developmentally regulated expression of specific tau sequences.

Tau protein undergoes a shift in its molecular mass and its electrophoretic complexity during early postnatal development. We have sequenced a tau cDNA from an adult rat brain expression library and have found two inserted sequences. One of these inserts predicts a fourth repeated sequence homologous to the other three in the carboxyl end of tau that have the property of microtubule binding. Oligonucleotide probes directed against the insert hybridized only to tau mRNA at postnatal time points, even though tau is first expressed as early as embryonic day 13. A probe directed against the junction revealed expression of non-insert-containing tau mRNA from embryonic day 14 until postnatal day 8, after which time there was an abrupt decline in the expression of this immature form. Comparison of the developmentally expressed tau sequences with those sequences obtained directly from Alzheimer paired helical filaments revealed the presence of both the mature and the immature tau mRNA sequences.

Alzheimer Disease↗
PubMed1988

Partial sequence of MAP2 in the region of a shared epitope with Alzheimer neurofibrillary tangles.

A 3.3-kilobase DNA complementary to human microtubule-associated protein 2 (MAP2) was sequenced by the dideoxy method. The 3' end terminates at an internal EcoRI site before the polyA tail. Due to the arrangement of the cDNA insert in the lambda gt11 vector, the MAP2 fragment is not fused to beta-galactosidase when expressed. The Chou Fasman algorithm for the initial 58 amino acids from the first in-frame methionine predicts an alpha helix. Beyond this point, a series of turns is predicted until amino acid 160. The frequent presence of basic residues in proximity to serines or threonines is consistent with multiple phosphorylation sites. The minimum specificity determinant for Ca2+/calmodulin-dependent kinase is repeated 13 times. The sequence of a region containing a MAP2 epitope that is shared with the Alzheimer neurofibrillary tangle was determined by DNase treatment of the cDNA and antibody selecting the small resultant clones in a lambda gt11 sublibrary. Likewise, a MAP2 epitope that is not shared with the neurofibrillary tangle also has been located. Both epitopes are in the projection portion of the molecule. A bovine MAP2 cyanogen bromide fragment, which contains the epitope shared with the neurofibrillary tangle, is partially insoluble under aqueous conditions, probably due to the aggregation of oppositely charged residues. Thus, rapid cleavage of MAP2 to small peptides is probably necessary in vivo to prevent the aggregation of larger cleavage fragments.

Alzheimer Disease↗