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Biomedical subjects

S Daniel

Publications and source records attributed to S Daniel.

At least 37 records · Page 2Linked to original sources
PubMed1994

Characterization of a fluorescent substance P analog.

We describe the development and characterization of substance P labeled at Lys3 with fluorescein ([fluorescein Lys3]SP) as a fluorescent probe for the neurokinin 1 (NK1) receptor. [fluorescein Lys3]SP is an agonist at the human NK1 receptor, with an affinity for both the high-affinity and low-affinity binding states of the receptor approximately 6-fold lower than that of substance P. Binding of the probe to the human NK1 receptor expressed in Sf9 insect cells was observed directly by monitoring either a decrease in fluorescence intensity or an increase in anisotropy of the [fluorescein Lys3]SP. Detection by anisotropy gave the larger signal and thus was used to characterize the interaction of [fluorescein Lys3]SP with the receptor. The anisotropy of the bound ligand was 0.17, compared to 0.04 for the free ligand. The fluorescence was quenched by about 15% upon binding to the receptor. Bound [fluorescein Lys3]SP was displaced by unlabeled SP and by the quinuclidine antagonist L-703,606. As expected for an agonist, binding was also reduced by the addition of the nonhydrolyzable guanine nucleotide analog GppNHp. [fluorescein Lys3]SP should provide a useful structural and kinetic probe for the NK1 receptor.

Amino Acid Sequence↗
PubMed1994

Critical phosphorylation sites for acetyl-CoA carboxylase activity.

Acetyl-CoA carboxylase (ACC) is rapidly regulated by reversible phosphorylation; phosphorylation inactivates ACC, whereas dephosphorylation activates the enzyme. Among protein kinases only cAMP-dependent protein kinase and 5'-AMP-dependent protein kinase can inactivate ACC; cAMP-dependent protein kinase phosphorylates Ser-77 and -1200; 5'-AMP-dependent protein kinase phosphorylates Ser-79, -1200, and -1215. In this report, the construction and expression of ACC cDNA containing the entire coding region (7.2 kilobase pairs) is described. In order to identify the critical phosphorylation site(s) for each protein kinase, we introduced site-specific mutations at Ser-77, -79, -1200, and -1215 of ACC cDNA and a series of mutated ACCs containing various combinations of these four mutated sites was expressed. By examination of the various mutant ACCs, we provided evidence that the effect of cAMP-dependent protein kinase is entirely mediated by the phosphorylation of Ser-1200 and that Ser-79 is important for 5'-AMP-dependent protein kinase action in vitro.

Acetyl-CoA Carboxylase↗
PubMed1994

Trophic exchanges between parent and young during development of Glossiphonia complanata (Annelida, Hirudinea).

Glossiphoniids are iteroparous hirudineans that brood their offspring. The young are attached by the posterior sucker to the parent's ventral side until development is complete. The weight loss of the brooding adults is commonly attributed to their reduced possibility of feeding and to the increased metabolic expense for movements needed to ventilate the offspring. The present study showed that there is a passage of nutritive substrates between the parental body wall and the young's sucker. A possible correlation between this passage and the reabsorption of some muscle fibers that occurs in the adult's body wall is also analyzed.

3-O-Methylglucose↗
PubMed1994

Cloning of human acetyl-CoA carboxylase cDNA.

Acetyl-CoA carboxylase is the rate-limiting enzyme in the biogenesis of long-chain fatty acids. In order to understand the mechanisms that regulate human acetyl-CoA carboxylase at the gene level, and the relationship between its structure and function, cDNA clones for human acetyl-CoA carboxylase have been isolated and sequenced. Human acetyl-CoA-carboxylase cDNA contains 7020 nucleotides encoding a protein of 2340 amino acids with a calculated relative molecular mass of 264575. The human enzyme shows approximately 85% identity in nucleotide sequence with previously cloned rat acetyl-CoA carboxylase, and shows 90% identity in the amino acid sequence. Two human acetyl-CoA-carboxylase mRNA species, which differ in the 5' untranslated region with the same coding sequence, have been identified. The sequence analysis reveals that type I and type II acetyl-CoA-carboxylase mRNA contain 313- and 173-base-long 5' untranslated regions, respectively. The first 240 nucleotides in the 5' untranslated region of type I acetyl-CoA-carboxylase mRNA replace the first 100 nucleotides of the (G + C)-rich region of the 5' untranslated region of the type II mRNA. These two species of mRNAs are the only species of human ACC mRNA which have been detected compared to at least five species in rat tissues, and they are expressed in a tissue-specific manner.

Acetyl-CoA Carboxylase↗
PubMed1994

Alterations in glutathione levels in Parkinson's disease and other neurodegenerative disorders affecting basal ganglia.

Reduced glutathione (GSH) and oxidized glutathione (GSSG) levels were measured in various brain areas (substantia nigra, putamen, caudate nucleus, globus pallidus, and cerebral cortex) from patients dying with Parkinson's disease, progressive supranuclear palsy, multiple-system atrophy, and Huntington's disease and from control subjects with no neuropathological changes in substantia nigra. GSH levels were reduced in substantia nigra in Parkinson's disease patients (40% compared to control subjects) and GSSG levels were marginally (29%) but insignificantly elevated; there were no changes in other brain areas. The only significant change in multiple-system atrophy was an increase of GSH (196%) coupled with a reduction of GSSG (60%) in the globus pallidus. The only change in progressive supranuclear palsy was a reduced level of GSH in the caudate nucleus (51%). The only change in Huntington's disease was a reduction of GSSG in the caudate nucleus (50%). Despite profound nigral cell loss in the substantia nigra in Parkinson's disease, multiple-system atrophy, and progressive supranuclear palsy, the level of GSH in the substantia nigra was significantly reduced only in Parkinson's disease. This suggests that the change in GSH in Parkinson's disease is not solely due to nigral cell death, or entirely explained by drug therapy, for multiple-system atrophy patients were also treated with levodopa. The altered GSH/GSSG ratio in the substantia nigra in Parkinson's disease is consistent with the concept of oxidative stress as a major component in the pathogenesis of nigral cell death in Parkinson's disease.

Aged↗
PubMed1994

Glutathione-related enzymes in brain in Parkinson's disease.

The activities of enzymes related to glutathione synthesis, degradation, and function were analyzed in various brain regions (cerebral cortex, caudate nucleus, putamen, globus pallidus, and substantia nigra) from patients dying with pathologically proven Parkinson's disease (PD) and multiple system atrophy (MSA), and from matched controls with no neurological disorder. The activity of the glutathione degradative enzyme, gamma-glutamyltranspeptidase, was selectively elevated in substantia nigra (SN) in PD. In contrast, the activity of the synthetic enzyme, gamma-glutamylcysteine synthetase, was unaltered in SN and other brain areas in PD. Similarly, glutathione peroxidase and glutathione transferase activities were unaltered in SN or in other brain regions in PD. gamma-Glutamylcysteine synthetase, gamma-glutamyltranspeptidase, glutathione peroxidase, and glutathione transferase activities were normal in SN and most other brain areas in MSA. However, glutathione peroxidase activity was increased in the lateral globus pallidus and caudate nucleus in MSA. The depletion of reduced glutathione (GSH) in the SN in PD, with no change in oxidized glutathione (GSSG), may be due to efflux of GSH mainly out of glia promoted by gamma-glutamyltranspeptidase, perhaps with additional increased conversion of GSH to GSSG (which itself is transported out of cells by gamma-glutamyltranspeptidase), in response to increased hydrogen peroxide formation.

Aged↗
PubMed1994

Fetus-like dystrophin expression and other cytoskeletal protein abnormalities in centronuclear myopathies.

We have investigated supposed maturational arrest of muscle in centronuclear myopathies (CNMs) by characterizing the expression of dystrophin, other cytoskeletal proteins, and fetal myosin in the muscle fibers of 9 CNM patients (4 sporadic, 3 familial, 2 adult sporadic). Dystrophin and beta-spectrin localized intracytoplasmically in centrally nucleated fibers. Talin and vinculin were normally expressed. Desmin was radially organized in several fibers in all patients. Scattered vimentinpositive fibers were found in 3 cases. Six myotonic dystrophy cases and 4 inflammatory myopathy cases with regenerating fibers were also studied: dystrophin and the membrane cytoskeletal proteins were normally expressed in the former; and dystrophin, spectrin, and vinculin were reduced in the latter. Intracytoplasmic dystrophin is further evidence of maturational arrest in CNMs. Spectrin and dystrophin codistribute in these pathological conditions as in normal muscle. We conclude that the altered cytoskeletal network found in CNMs likely plays a pathogenetic role in these conditions.

Adult↗
PubMed1994

An evaluation of a new teenage clinic and its impact on teenage conceptions in Nottingham from 1986 to 1992.

A new contraceptive clinic for teenagers was developed in the centre of Nottingham from 1987 to 1992 and provided care for over 1500 young people in its first three years. Twenty-five percent of clients were aged 16 years and 32% aged 15 or younger. Sixty-seven percent were in full-time education and young unemployed people were under-represented. The majority were young women, who came for routine contraception, usually the oral contraceptive or condom. Seventeen percent came for emergency contraception and 8% for abortion counselling and referral. Over the period 1986 to 1992, data on conceptions for teenage women and women aged over 20 years, who were resident in Nottingham Health district, were compared and when corrected for the estimated population showed that there had been no reduction in teenage conception rates; reasons for this are discussed. The value of conception rates as a measure of quality of sexual health care for teenagers is questioned and other more qualitative methods suggested.

Abortion, Induced↗
PubMed1994

Conversion of cycles involving ovarian hyperstimulation with intra-uterine insemination to in-vitro fertilization.

Conversion to in-vitro fertilization (IVF) and embryo transfer as an alternative to cancellation was offered in 27 consecutive cycles of controlled ovarian hyperstimulation and intra-uterine insemination (IUI) cycles with excessive follicular development in patients with idiopathic infertility. IVF and embryo transfer was performed in 25 cycles, resulting in 13 pregnancies (52%), with 22% of couples having at least two embryos cryopreserved. The pregnancies have resulted in one singleton and two twin births, one spontaneous abortion, and nine ongoing pregnancies (including one triplet gestation). Four patients developed severe ovarian hyperstimulation syndrome (OHSS) after IVF and embryo transfer, including two cases requiring paracentesis. Three of four OHSS patients were pregnant, resulting in live births of healthy twins, one spontaneous abortion and one ongoing singleton gestation. In two cycles a spontaneous luteinizing hormone (LH) surge occurred, preventing oocyte retrieval. For these two women, drainage of all follicles except the five most likely to fertilize (18-22 mm diameter) was performed, followed by IUI, with no pregnancies or OHSS observed. Conversion of patients from IUI cycles to IVF/embryo transfer cycles avoids cancellation of the very cycles with the best chance of achieving pregnancy. OHSS remains a problem, necessitating extensive pre-IVF counselling and post-transfer vigilance.

Embryo Transfer↗
PubMed1994

Lack of correlation between the number of circulating B cells and the concentration of serum antibodies reactive with the HIV-1 envelope glycoprotein.

Cells obtained from the peripheral blood of HIV-infected patients and volunteers immunized with HIV-1 vaccines are commonly used to study anti-viral responses, since lymphocytes from the central lymphoid organs are difficult to obtain. Analyses involving PBMC implicitly assume that circulating B cells provide an accurate reflection of the systemic humoral response induced by the HIV antigens. We examined this assumption by comparing the number of B cells secreting IgG anti-gp160/120 antibodies in the peripheral circulation with serum antibody titers. Results indicate that neither the magnitude nor duration of the serologic response detected in HIV-infected patients or gp160/gp120-immunized volunteers reproducibly correlates with the number of B cells secreting anti-envelope antibodies in the blood.

AIDS Vaccines↗
PubMed1993

Determination of the specificities of monoclonal antibodies recognizing members of the CEA family using a panel of transfectants.

Carcinoembryonic antigen (CEA), one of the most clinically important tumor markers, is mainly used in the post-surgical surveillance of patients with colorectal carcinomas. CEA belongs to a large protein family, which includes cross-reacting antigens, e.g., non-specific cross-reacting antigens (NCAs) and biliary glycoprotein (BGP) as well as pregnancy-specific glycoproteins (PSGs). The genes encoding these proteins can be subdivided into the CEA and PSG subgroups. The members of the subgroups share antigenic determinants and show high similarity in amino-acid sequences. Their derived secondary structures show them to belong to the immunoglobulin superfamily. Due to the close relationship of the members of the CEA subgroup, it is very difficult to distinguish between the individual members with MAbs. Here we have used flow cytometric analysis of transfectants expressing individual members of the CEA subgroup as an alternative approach to determine the specificities of 13 MAbs. This allows us to examine the specificities of these antibodies for members of the CEA family, even of those which have not yet been characterized at the protein level. In addition, binding of the MAbs to NCAs expressed by polymorphonuclear cells (PMN) was tested by Western-blot analysis, immunoprecipitation and flow cytometry. Four antibodies bound exclusively to NCA-50/90 and one MAb (80H3) only to NCA-95. MAb 4/3/17 recognizes CEA and BGP on the surface of transfectants and NCA-160 from granulocytes. We assume that NCA-160 is a product of the BGP gene. On granulocytes, which do not express CEA, MAb 4/3/17 is specific for NCA-160 (BGP). Mutual inhibition of the MAbs binding to NCA-50/90 revealed 3 different epitope groups.

Antibodies, Monoclonal↗
PubMed1993

Different sets of afferents are demonstrated by the fluorescent tracers fast blue and rhodamine.

The fluorescent retrograde tracers Rhodamine B Isothiocyanate (RITC) and Fast Blue (FB) were injected either into the thalamic nucleus rotundus or into the complexus neck muscle in pigeons. Both in the rotundal and the peripheral motor preparations RITC yielded a 3-5 times larger number of afferent ipsilateral neurones than FB. While RITC additionally labelled a large number of contralateral afferents, virtually no labelled cells were detected contralateral to the injection site using FB. This selective omission of the contralateral input with FB was identical for both neural systems despite differences in injection volume, survival time, and transport length. In the present case, this structure-specific sensitivity of FB would lead to the erroneous conclusion that contralateral afferents are virtually non-existent in the visual tectofugal and the peripheral motor system. Thus, these results make it likely that the choice for a certain tracer may lead to different connectional interpretations of a neural system. Although the mechanism for these structure-specific sensitivity differences are unknown, it is suggested that tracers with lower effectivity like FB may be unable to label afferent structures with fewer axon terminals.

Afferent Pathways↗
PubMed1993

An aggressive philosophy in controlled ovarian stimulation cycles increases pregnancy rates.

To assess the effect of timing of human chorionic gonadotrophin (HCG) administration in ovarian stimulation cycles, the serum oestradiol concentration and follicle profile were compared with the clinical pregnancy rate in 582 ovarian stimulation-intra-uterine insemination (OS-IUI) cycles and 3917 in-vitro fertilization-embryo transfer (IVF-ET) cycles. The pregnancy rates increased exponentially with increasing oestradiol in both OS-IUI and IVF-ET cycles (R2 = 0.720, P < 0.001) but then decreased in OS-IUI cycles when the oestradiol concentration exceeded 5000 pmol/l (R2 = 0.936, P < 0.004) at HCG administration. In OS-IUI cycles the percentages of cycles with three or more mature follicles (> or = 18 mm diameter) increased up to an oestradiol concentration of 5000 pmol/l then declined, mirroring the pregnancy rate (R2 = 0.900, P = 0.01). The exponential increase in pregnancy rate with increasing oestradiol concentration in IVF-ET cycles suggests that high oestradiol concentration does not have a deleterious effect on endometrial receptivity. The decrease in pregnancy rate in OS-IUI cycles when oestradiol concentration exceeded 5000 pmol/l reflected fewer mature follicles, resulting from premature administration of HCG to avoid severe ovarian hyperstimulation syndrome (OHSS). We recommend that HCG administration be delayed until multiple follicles have reached maturity, and reducing the risk of severe OHSS by converting high risk OS-IUI cycles to IVF-ET, or if funds or facilities are unavailable, transvaginally draining all but four or five mature follicles.

Chorionic Gonadotropin↗
PubMed1992

Giant thoracoabdominal lymphangioma with features of lymphangiomyoma.

A 15-year-old girl who presented with cough and dyspnea was found to have a mediastinal tumor that clinically resembled a lymphangioma. The tumor was unusual for its large size and its histologic features, which showed smooth muscle proliferation, generally considered a feature of lymphangiomyoma.

Adolescent↗
PubMed1991

Activation of protein kinase C in lipid monolayers.

The potential of lipid monolayers spread at an air-water interface was investigated as a well defined membrane model able to support protein kinase C (PKC) association and activation. PKC association to a mixed phospholipid film (phosphatidylcholine, phosphatidylserine) could be detected by an increase of the monolayer surface pressure. This association was strikingly dependent upon the presence of submicromolar concentrations of Ca2+. The effect of Ca2+ resulted in an increase of the PKC penetration into the lipid core at a given permissive surface pressure as well as in a marked increase of the critical surface pressure (29-38 dynes/cm) above which the enzyme was excluded from the membrane. Inclusion of diacylglycerol or tetradecanoate phorbol acetate (TPA) did not modify the PKC-monolayer association in a detectable manner. PKC associated to the lipid layer exhibited the expected catalytic property and was fully activated when diacylglycerol or TPA was included in the membrane. PKC activity was highly dependent upon the surface pressure of the lipid monolayer, being optimal between 30 and 35 dynes/cm. Study of the compression isotherm of various diacylglycerol structures revealed that all potent PKC agonists exhibited an expanded liquid phase behavior with collapse pressure below 40 dynes/cm, in contrast to weak activators which showed condensed isotherms with high collapse pressure (approximately equal to 60 dynes/cm). These observations showed that the lipid monolayer system is well adapted to the study of the molecular mechanisms involved in the regulation of PKC activity at a model membrane interface. They are in line with the suggestion of a major role of Ca2+ in the association (translocation) of PKC to membrane in living cell and suggest that diacylglycerol (and TPA) might activate membrane-associated PKC through local change in the surrounding lipid phase organization.

Animals↗