Search PubMed⌕ Search

Biomedical subjects

K Stevens

Publications and source records attributed to K Stevens.

At least 37 records · Page 2Linked to original sources
PubMed1999

Effects of pregnancy and delivery on serum concentrations of Clara Cell Protein (CC16), an endogenous anticytokine: lower serum CC16 is related to postpartum depression

There is now some evidence that lower serum concentrations of Clara Cell Protein (CC16) are related to stress-induced anxiety, psychoses and major depression. This study was developed to determine whether serum CC16 is lowered in the early puerperium and whether Postnatal Depression and Postnatal Blues are associated with lower levels of serum CC16. Serum concentrations of CC16 were assayed in 17 non-pregnant women and in 98 pregnant women before delivery and 1 and 3 days after delivery. On each occasion the parturients completed the State version of the Spielberger State-Trait Anxiety Inventory (STAI) and the Zung Depression Rating Scale (ZDS). Serum CC16 was significantly lower in pregnant women, at the end of pregnancy as well as 1 and 3 days after delivery, than in the non-pregnant women. Serum CC16 was somewhat, although significantly, higher 1 and 3 days after delivery than before delivery. Parturients who developed a postpartum depression had significantly lower serum CC16 concentrations than women who did not. There were no significant differences in serum CC16 between the puerperal women whose STAI or ZDS scores increased in the puerperium and those whose scores did not. It is concluded that in puerperal women there is a decreased anti-inflammatory capacity in the serum, in part caused by lowered serum CC16, and that the latter may be related to the development of postpartum depression.

Journal Article↗
PubMed1999

Update of the Human MitBASE database.

Human MitBASE is a database collecting human mtDNA variants. This database is part of a greater mitochondrial genome database (MitBASE) funded within the EU Biotech Program. The present paper reports the recent improvements in data structure, data quality and data quantity. As far as the database structure is concerned it is now fully designed and implemented. Based on the previously described structure some changes have been made to optimise both data input and data quality. Cross-references with other bio-databases (EMBL, OMIM, MEDLINE) have been implemented. Human MitBASE data can be queried with the MitBASE Simple Query System (http://www.ebi.ac.uk/htbin/Mitbase/mit base.pl) and with SRS at the EBI under the 'Mutation' section (http://srs.ebi.ac.uk/srs5/). At present the HumanMitBASE node contains approximately 5000 variants related to studies investigating population polymorphisms and pathologies.

Animals↗
PubMed1999

Morphology of rhinoceros platelets.

Basic hematological information about rhinoceros species is limited. In this study, we have determined the platelet counts and described the platelet morphology of free-living white (Ceratotherium simum) and black (Diceros bicornis) rhinoceros using light and electron microscopy. The platelet counts of the two species were similar, but there were significant differences in platelet size as well as morphology between the species. The presence of large, nondiscoid platelet forms, resembling proplatelet or stress platelet forms, were observed in both, although not as often in the white rhinoceros as in the black rhinoceros.

Animals↗
PubMed1999

Genetic basis for lipopolysaccharide O-antigen biosynthesis in bordetellae.

Bordetella bronchiseptica and Bordetella parapertussis express a surface polysaccharide, attached to a lipopolysaccharide, which has been called O antigen. This structure is absent from Bordetella pertussis. We report the identification of a large genetic locus in B. bronchiseptica and B. parapertussis that is required for O-antigen biosynthesis. The locus is replaced by an insertion sequence in B. pertussis, explaining the lack of O-antigen biosynthesis in this species. The DNA sequence of the B. bronchiseptica locus has been determined and the presence of 21 open reading frames has been revealed. We have ascribed putative functions to many of these open reading frames based on database searches. Mutations in the locus in B. bronchiseptica and B. parapertussis prevent O-antigen biosynthesis and provide tools for the study of the role of O antigen in infections caused by these bacteria.

Bordetella↗
PubMed1999

Splice variants of the mouse Tec gene are differentially expressed in vivo.

Tec is a cytoplasmic protein tyrosine kinase that participates in the signalling pathways of a broad range of cytokines. Up to five different Tec isoforms have been reported in the literature. We report here the genomic organisation of the mouse Tec gene and the tissue expression pattern of the two predominant transcripts, TecIII and TecIV. The mouse Tec gene consists of 18 exons, spans more than 86 kb, and is 2.6 kb 5' to the gene for Txk, a Tec family member. Comparison of mouse and human Btk, human TXK, and mouse Tec genomic structures shows a high level of conservation of exon/intron boundaries. Compared with TecIV, the TecIII transcript has a 66-bp deletion in the SH3 domain encoding region and is revealed here to arise by alternative splicing of exon 8. We show that both TecIII and TecIV are expressed as early as embryonic day 10.5 in mouse development, as well as in adult and embryonic organs. The ratio of TecIV to TecIII expression is markedly reduced in adult liver and kidney tissues and d16 embryonic limb.

Alternative Splicing↗
PubMed1998

Binding of the winged-helix transcription factor HNF3 to a linker histone site on the nucleosome.

The transcription factor HNF3 and linker histones H1 and H5 possess winged-helix DNA-binding domains, yet HNF3 and other fork head-related proteins activate genes during development whereas linker histones compact DNA in chromatin and repress gene expression. We compared how the two classes of factors interact with chromatin templates and found that HNF3 binds DNA at the side of nucleosome cores, similarly to what has been reported for linker histone. A nucleosome structural binding site for HNF3 is occupied at the albumin transcriptional enhancer in active and potentially active chromatin, but not in inactive chromatin in vivo. While wild-type HNF3 protein does not compact DNA extending from the nucleosome, as does linker histone, site-directed mutants of HNF3 can compact nucleosomal DNA if they contain basic amino acids at positions previously shown to be essential for nucleosomal DNA compaction by linker histones. The results illustrate how transcription factors can possess special nucleosome-binding activities that are not predicted from studies of factor interactions with free DNA.

Amino Acid Sequence↗
PubMed1998

The mitBASE human dataset structure.

MitBASE is a comprehensive and integrated mitochondrial genome database funded within the EU BIOTECH PROGRAM. It is a project for the development and implementation of an integrated and comprehensive database of mitochondrial data which will collect all available information from different organisms and from intraspecies variants and mutants. The present paper describes the structure of the Human dataset in mitBASE where human molecular data are distinguished from clinical and pathological data. MitBASE home page address is: http://www.ebi.ac.uk/htbin/Mitbase/mitb ase.pl

Computer Communication Networks↗
PubMed1998

Susceptibility of stromelysin 1-deficient mice to collagen-induced arthritis and cartilage destruction.

OBJECTIVE: It has long been proposed that stromelysin is one of the major degradative matrix metalloproteinases responsible for the loss of cartilage in rheumatoid arthritis (RA) and osteoarthritis (OA). This hypothesis was tested by examining the arthritic paws of stromelysin 1 (SLN1)-deficient mice for loss of cartilage and for generation of neoepitopes that would be indicative of aggrecan cleavage. METHODS: The SLN1 gene was inactivated in murine embryonic stem cells, and knockout mice deficient in SLN1 activity were bred onto the B10.RIII background. The incidence and severity of collagen-induced arthritis (CIA) were compared in wild-type and knockout mice. Paws from mice with CIA were examined for loss of cartilage and for proteoglycan staining, as well as for the generation of the neoepitope FVDIPEN341. RESULTS: SLN1-deficient mice developed CIA, as did the wild-type N2 mice. Histologic analyses demonstrated no significant differences among the B10.RIII, wild-type, and knockout mice in loss of articular cartilage and proteoglycan staining. No decrease in the FVDIPEN341 epitope was observed in the SLN1-deficient mice. CONCLUSION: Disruption of the SLN1 gene neither prevents nor reduces the cartilage destruction associated with CIA. Moreover, SLN1 depletion does not prevent the cleavage of the aggrecan Asn341-Phe342 bond.

Animals↗
PubMed1998

Schizophrenia, sensory gating, and nicotinic receptors.

A series of human and animal investigations has suggested that altered expression and function of the alpha7-nicotinic cholinergic receptor may be responsible for the auditory sensory gating deficit characterized in schizophrenia patients and their relatives as diminished suppression of an auditory-evoked response (P50) to repeated stimuli. This finding, in conjunction with evidence for familial transmission of this sensory gating deficit, suggests a pathogenic role of the gene for the alpha7-nicotinic receptor in schizophrenia. This article considers the possible effects of this dysfunction in a broader context. Not only is this dysfunction consistent with difficulties in sensory gating, but it might also predispose patients to problems with learning efficiency and accuracy. Such learning problems could underlie schizophrenia patients' delusional thinking, hallucinations, and social dysfunction. In addition, heavy smoking in many schizophrenia patients is consistent with the high concentration of nicotine necessary to activate the receptor and with the receptor's extremely rapid desensitization. Finally, the receptor's possible role in cell growth and differentiation should be considered in connection with developmental deficits and other cellular abnormalities in schizophrenia.

Animals↗
PubMed1997

Regulation of the mating pheromone and invasive growth responses in yeast by two MAP kinase substrates.

BACKGROUND: In the budding yeast Saccharomyces cerevisiae, components of a single mitogen-activated protein (MAP) kinase pathway transduce two distinct signals, each of which activates an independent developmental programme: peptide mating pheromones initiate the mating response, whereas nutrient limitation initiates filamentous growth. One of the MAP kinases in this pathway, Fus3, triggers mating but antagonizes filamentous growth, while the other, Kss 1, preferentially triggers filamentous growth. Both kinases activate the same transcription factor, Ste 12, which can stimulate gene expression specific to each of the developmental programmes. The precise mechanism by which these MAP kinases activate Ste 12, however, is not clear. RESULTS: Two newly identified proteins, Rst 1 and Rst 2 (also known as Dig1 and Dig2), were found to associate physically with Fus3 and Ste12. Rst1 and Rst2 were prominent substrates in kinase reactions of Fus3 immune complexes from pheromone-treated cells. Association of Fus3 with Ste12 required Rst1 and Rst2, and activation of Fus3 by pheromone caused release of Ste12 from the Fus3 complex. Although rst1 and rst2 single mutants had no obvious phenotype, both filamentous growth and mating-specific gene expression were constitutive in rst1 rst2 double mutants. The phenotype of rst1 rst2 cells required Ste12 function, but did not require the function of upstream kinases. Consistent with Rst1 and Rst2 having a role in Ste12 regulation, both proteins were localized to the nucleus. CONCLUSIONS: Rst1 and Rst2 repress the mating and filamentous growth responses of S. cerevisiae by directly inhibiting Ste12. Activation of Fus3 or Kss1 may cause phosphorylation-dependent release of Ste12 from Rst1/Rst2 and thereby activate Ste12-dependent transcription.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1997

Impala, Aepyceros melampus, platelets: count, morphology, and morphometric observations.

There is little published information regarding the platelets of impala (Aepyceros melampus). In this study we determined the platelet counts of 12 healthy adult male impalas and describe the morphology of the platelets. The platelet counts of the animals are high. Although the platelets appear to be extremely small, they have the characteristic ultrastructure of the platelets of the family Bovidae. They have few but prominent alpha-granules. Other cytoplasmic inclusions are the dense bodies, microtubules, mitochondria, and glycogen. There is no surface-connecting canalicular system present.

Animals↗
PubMed1997

Umbilical cord blood transplants: treatment for selected hematologic and oncologic diseases.

Umbilical cord blood transplantation is a rapidly growing form of treatment for many types of cancer and hematologic disorders. The concepts behind the use of umbilical cord blood transplantation are based on information gained from experience in bone marrow transplantation. Previously discarded as human waste, the blood in the umbilical cord remnant and the placenta has been observed to be rich in hematopoietic stem cells. Techniques for collecting these stem cells from the placenta may vary among the institutions, physicians, and other health care providers, including midwives and nurse practitioners, involved with this procedure. This source of hematopoietic stem cells in transplantation has many advantages, disadvantages, and controversies associated with its use.

Fetal Blood↗
PubMed1997

The ultrasound appearances of galactocoeles.

Galactocoeles are an uncommon cause of breast masses, usually occurring in lactating women. The purpose of this study was to review the ultrasound (US) features of galactocoeles presenting to the Nottingham Breast Unit. Eight women with galactocoeles were scanned during 1994 and 1995. All the scans were abnormal, 50% of lesions were cystic or multicystic, 37% mixed cystic/solid and 13% appeared solid. A fat-fluid level was seen in only one case. Two of the cystic/solid lesions had ill defined solid components, raising the possibility of an intracystic carcinoma. All cases were confirmed by the aspiration of milk and clinical resolution following aspiration.

Adult↗
PubMed1997

Targeted disruption of the tumor necrosis factor-alpha gene: metabolic consequences in obese and nonobese mice.

To address the hypothesis that tumor necrosis factor (TNF)-alpha has a role in obesity-associated insulin resistance or the regulation of in vivo lipid metabolism, mice with targeted disruption of the TNF-alpha gene were generated and studied. The absence of TNF-alpha protein in TNF-null (-/-) mice was confirmed. Lean or obese (gold-thioglucose [GTG]-injected) homozygous (-/-) mice were compared with lean or obese age- and sex-matched wild-type (+/+) mice derived from the same line at 13, 19, and 28 weeks of age. The following parameters were significantly affected in lean -/- versus +/+ mice: Body weight was not affected until week 28 (decreased by 14%); epididymal fat pad weight also decreased (25%) at this time, as did percentage body fat (16%), while percentage body protein was increased 13%. Fed plasma insulin levels decreased 47% (28 weeks), triglyceride levels decreased (all three ages; maximum 35% at 19 weeks), and fed plasma leptin decreased 33% (28 weeks). Fasting glucose was slightly (10%) reduced, but the glucose response to an oral glucose tolerance test (OGTT) was not affected. There was a trend (NS) toward increased total adipose tissue lipoprotein lipase in -/- versus +/+ mice. GTG-treatment resulted in obese -/- and +/+ mice with equal mean body weights (42 and 58% increased weight versus lean mice). The following parameters were significantly different in obese -/- mice: fasting plasma glucose decreased 13% (28 weeks), fed plasma insulin decreased 67% (28 weeks), and insulin response to OGTT was decreased by 50%. For both groups of obese mice, glucose levels during the OGTT were substantially increased compared with those in lean mice; however, mean stimulated glucose levels were 20% lower in obese -/- versus +/+ mice. We conclude 1) that TNF-alpha functions to regulate plasma triglycerides and body adiposity and 2) that although TNF-alpha contributes to reduced insulin sensitivity in older or obese mice, the absence of TNF-alpha is not sufficient to substantially protect against insulin resistance in the GTG hyperphagic model of rodent obesity.

Animals↗
PubMed1996

Ultrastructure of buffalo, Syncerus caffer, platelets: comparison with bovine and human platelets.

Platelets are found in the blood of all mammals and serve the same basic hemostatic functions in all. Species differences in the morphology and activities of platelets in human and domesticated animals have been observed, but there is little published information regarding the blood pictures of wild animals. In this study, the ultrastructure of buffalo platelets was compared with that of bovine and human platelets. Buffalo platelets were found to be smaller than human platelets and intracellularly had larger alpha-granules, possessed distinctive dense granules and a more distinct microtubuli system, but they lacked the open canalicular system observed in the human type. This morphology is similar to that of cattle platelets.

Animals↗