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Biomedical subjects

M Smith

Publications and source records attributed to M Smith.

At least 487 records · Page 27Linked to original sources
PubMed1996

Transcriptional regulation of the tissue factor gene in human epithelial cells is mediated by Sp1 and EGR-1.

Tissue factor (TF) gene expression is rapidly induced in epithelial cells by phorbol 12-myristate 13-acetate and serum. We have shown that this induction is mediated by a novel serum response region (SRR) (-111 to +14 bp) within the human TF promoter. In this study, we characterized cis-acting genetic elements within the SRR that regulated basal and inducible expression of the TF gene in HeLa cells. Gel mobility shift assays using oligonucleotides spanning the entire SRR identified three 12-base pair (bp) motifs within subregions 1, 2, and 3 that bound constitutively expressed Sp1 and inducibly expressed EGR-1. Analysis of protein binding to these 12-bp motifs by competition with Sp1 and EGR-1 sites, mutation, and antibody supershift experiments indicated that they each contained distinct EGR-1 and Sp1 sites that overlapped by 6 bp. Functional studies using HeLa cells transfected with plasmids containing the wild-type TF promoter (-111 to +14 bp) or derivatives containing mutations in the three Sp1 and/or EGR-1 sites examined basal and inducible expression. The Sp1 sites mediated basal promoter activity, and both Sp1 and EGR-1 sites were required for maximal induction of the TF promoter by phorbol 12-myristate 13-acetate or serum. These data indicated that TF gene expression in HeLa cells was regulated by both Sp1 and EGR-1.

Base Sequence↗
PubMed1996

Platelet activation and thrombosis: studies in a patient with essential thrombocythemia.

Recent advances permit the detection of activated platelets using specific monoclonal antibodies and flow cytometry. Nevertheless, there are few reports in which activated platelets have been studied over a period of time in patients at risk for thrombosis. Our patient S.D. has essential thrombocythemia and a prothrombotic state manifested in two major thrombotic episodes involving the portal vein and a mesenteric artery. Investigation revealed both spontaneous aggregation and hyperaggregability in response to ADP and the presence of activated platelets in platelet-rich plasma as revealed by flow cytometry. Interestingly, the activated platelets were recognized by an anti-RIBS ("receptor-induced binding site") monoclonal antibody that recognized bound fibrinogen but not by antibodies reactive with antigens whose presence on the platelet surface was secretion dependent. Treatment with aspirin inhibited spontaneous platelet aggregation but had little effect on the activated platelet profile. A change of therapy to ticlopidine suppressed expression of platelet activation markers. Treatment with ticlopidine has continued for 1 year so far without further thrombotic complications.

Adenosine Diphosphate↗
PubMed1996

Identity formation and religious orientation among high school students from the United States and Canada

Two studies were conducted to examine the relations between Marcia's four identity statuses and Allport and Ross' four religious orientations. Study 1 was conducted among 38 Mormon and 47 non-Mormon high school students living in a predominantly Mormon Utah community. Study 2 was conducted among 102 Jewish high school students living in Ontario, Canada. It was revealed through the use of MANCOVA procedures that, in both studies, identity diffusion was associated with the extrinsic religious orientation. The indiscriminate proreligious scored significantly higher on foreclosure than the intrinsic and nonreligious groups, and the extrinsic scored significantly higher on moratorium than the intrinsic and nonreligious groups in Study 1. The indiscriminate proreligious scored significantly higher on identity achievement than those classified as extrinsic or nonreligious in Study 2. The indiscriminate proreligious and intrinsic religious orientations were associated with higher scores in three subscales of ethnic identity for the Jewish adolescents. Potential moderating influences of religious orthodoxy, religious attendance, grade, and gender were found to not operate between identity and religious orientation.

Journal Article↗
PubMed1996

High yield hepatocyte isolation from pig livers for investigation of hybrid liver support systems: influence of collagenase concentration and body weight.

Cultured hepatocytes would be required in large quantities if a hybrid liver support system became available. We have therefore performed a study of larger scale enzymatic hepatocyte isolation on whole pig livers. A new method of open-loop and recirculating perfusion in five steps using both the portal venous and the hepatic arterial vascular systems has been developed. In a study of the yield and cell viability of hepatocytes afer isolation, the collagenase concentration of the perfusate was investigated over a range of 0.02 to 0.15%. The effect of animal weight on yield and cell viability was determined within the body weight range of 6 to 40 kg. At collagenase concentrations of less than 0.08%, yield and viability declined. As collagenase concentration increased, the yield continuously increased while the viability peaked at 0.1%. There was a decline of viability and yield with rising body weight. Optimal results were obtained with the lowest body weight (6 kg) which gave a yield of 95% (g wet weight) and a viability of 98% (trypan blue). This novel five-step collagenase perfusion technique with arterial perfusion appears to be reproducible and safe. Application of this method enables the large scale investigations to be undertaken towards the development of hybrid liver support.

Animals↗
PubMed1996

Pediatric drug development: a perspective from the Cancer Therapy Evaluation Program (CTEP) of the National Cancer Institute (NCI).

Well-designed and carefully conducted pediatric phase 1 trials are critical to the process of evaluating new agents for potential benefit in children with cancer, and the National Cancer Institute (NCI) has for a number of years sponsored pediatric phase I trials. The development of new agents for children with cancer differs in important ways from drug development for adults with cancer, primarily necessitated by the smaller number of children eligible for phase I trials in comparison to adults. Pediatric drug development is characterized by a greater need to prioritize new agents for evaluation, since many more agents can be evaluated in adults than can be evaluated in children. Pediatric phase I trials are also commonly conducted as multi-institutional collaborations, since most single institutions do not have enough eligible patients to complete phase I trials within a reasonable time. In addition, pediatric phase I trials begin at doses close to the adult maximum tolerated dose, thereby minimizing the number of patients required to complete pediatric phase I trials. While pediatric phase I trials have traditionally evaluated conventional cytotoxic agents, new classes of agents with distinctive mechanisms of action are entering clinical evaluation. These agents target specific cellular proteins (e.g., protein tyrosine kinases, protein kinase C isoforms, enzymes involved in controlling progression through the cell cycle). Determining whether these agents with specificity for critical cellular proteins will be effective anti-cancer agents will be an important objective of pediatric clinical investigations in the coming years.

Antineoplastic Agents↗
PubMed1996

Tumor necrosis factor priming of peripheral blood neutrophils from rheumatoid arthritis patients.

Recently it was shown that tumor necrosis factor-alpha (TNF) receptors on neutrophils may be down-regulated after stimulation with proinflammatory mediators. Since in rheumatoid arthritis neutrophils are likely to encounter these mediators in the circulation, we tested the hypothesis that rheumatoid arthritis neutrophil TNF receptors are down-regulated. Peripheral blood neutrophils from patients with rheumatoid arthritis and healthy subjects were compared with respect to their TNF binding activity and ability to be primed by TNF. There were no differences between rheumatoid arthritis and control neutrophils in receptor-mediated TNF binding, superoxide release in response to agonist, and TNF priming of this respiratory burst or in the ability to degrade cartilage in vitro and TNF priming for increased cartilage damage. It is evident that rheumatoid arthritis blood neutrophils retain the ability to bind TNF and can be primed by TNF for increased oxygen radical production and augmented cartilage damage. These findings further implicate the role of neutrophils in the pathogenesis of arthritis.

Aged↗
PubMed1996

The safety assessment of novel foods. Guidelines prepared by ILSI Europe Novel Food Task Force.

The diversity of novel foods and novel ingredients covered by the scope of the EU regulation is such that a check list approach to safety evaluation is inappropriate. Rather, a case-by-case approach is required taking into account the composition of the novel food, its intake, its role in the diet and the intended target group. The SAFEST approach provides a means of targeting the safety evaluation on those aspects, nutritional or toxicological, of a novel food which are of particular concern. Using this approach, novel foods are assigned to one of three classes on the basis of certain background information. For those novel foods which can be shown to be in SAFEST class 1, namely those which are substantially equivalent to a traditional counterpart, no further information is required to demonstrate their safety. For those novel foods in SAFEST class 2, i.e. those sufficiently similar to a traditional counterpart or differing from it only in particular, well defined, characteristics, the evaluation will focus on those differences. Only in the case of novel foods which are not in class 1 or class 2 is extensive testing of the whole food likely to be required. Even in these cases, the testing should follow a scientifically-based hierarchical approach involving: literature reviews; chemical analysis; appropriate in vitro and in vivo tests; and, if necessary, confirmation of safety and nutritional value in humans. Examination of the causes of any adverse effects reported by consumers after the novel food or ingredient has been approved and is introduced into the market may provide additional reassurance of safety.

Animals↗
PubMed1996

In situ hybridization analysis of vasopressin mRNA expression in the mouse hypothalamus: diurnal variation in the suprachiasmatic nucleus.

The distribution, and diurnal variation of AVP mRNA-expressing neurons in the hypothalamus of the mouse has been investigated using in situ hybridization histochemistry. In general, cells hybridizing with an AVP mRNA-specific oligonucleotide probe in the mouse hypothalamus exhibit a similar distribution to the well-characterized distribution of AVP nuclei in the rat, but species-specific patterns of expression have been observed, a finding that confirms the results of earlier immunocytochemical studies. For example, prominent groups of AVP mRNA expressing cells are found in the region between the paraventricular (PVN) and suprachiasmatic (SCN) nuclei, forming the distinct mouse accessory nucleus, and a periventricular group that merges with the PVN neurons. Sampling of brains during both phases of the daily cycle (either 10.00 h (light) or 22.00 h (dark)) revealed a marked and significant variation in AVP mRNA abundance in the SCN whereas a similar variation was not consistently observed in the magnocellular neurons of the supraoptic nucleus (SON). This study has confirmed the distribution of AVP-synthesizing neurons in the mouse hypothalamus, and provided an anatomical substrate for molecular genetic studies in this species that are designed to investigate the basis of neuronal rhythmicity.

Animals↗
PubMed1996

Role of ubiquitin carboxyl terminal hydrolase in the differentiation of human acute lymphoblastic leukemia cell line, Reh.

We have previously demonstrated that the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA), induces differentiation of the acute lymphoblastic leukemia cell line, Reh, to a mature non-dividing state. Associated with this differentiation is the expression of ubiquitin carboxyl terminal hydrolase (UCH-L1). To investigate the role of UCH-L1 in TPA-induced Reh differentiation and apoptosis, molecular and chemical inhibition was used. Molecularly, a sequence-specific antisense oligodeoxynucleotide (AODN) directed against UCH-L1 transcript was used to inhibit the expression of the gene. In addition, its complementary sense oligodeoxynucleotide (SODN) was used to indicate the specificity of AODN action. Chemically, sodium borohydride (NaBH4), an inhibitor of UCH-L, was used to block the transcript product. TPA-induced changes in Reh cell growth and morphology, UCH-L1 protein expression, apoptosis contour, surface phenotype, and enzymatic profile were assessed in the presence or absence of NaBH4, AODN or SODN. As previously reported, TPA induced Reh cells to differentiate into monocytoid B lymphocytes and stimulated the apoptotic pathway. However, adding NaBH4 or AODN inhibited the TPA effect on all parameters measured except apoptosis. The sequence in which NaBH4 or AODN were added in relation to TPA did not affect any of the response variables measured. The use of SODN did not influence any of the parameters measured, indicating the specificity of the action. Thus, we conclude that UCH-L1 is involved in the differentiation process of the lymphoblastic leukemia cell line, Reh. Our data suggest that TPA-induced apoptosis of Reh cells has a separate pathway from that of differentiation or that UCH-L1 expression is independent of the apoptotic pathway.

Adolescent↗
PubMed1996

Use of near infrared spectroscopy to estimate cerebral blood flow in conscious and anaesthetized adult subjects.

Near infrared spectroscopy (NIRS) can be used to quantify cerebral haemodynamic states non-invasively and to estimate cerebral blood flow (CBF). In the first part of this study we have compared CBF measurements in conscious and anaesthetized subjects. In the second part we have compared paired measurements made during anaesthesia, first on the scalp and then the dura after craniotomy. Mean CBF was 17 (SD 7) ml 100 g-1 min-1 in the conscious subjects compared with 21 (8) ml 100 g-1 min-1 on the scalp during anaesthesia (P > 0.1). Mean CBF on the dura was 68 (21) ml 100 g-1 min-1 (P < 0.0001). Computer modelling suggests that the difference in magnitude between scalp and dura measurements of CBF is likely to be caused by the optical effect of extracerebral tissue which powerfully scatters light passing through it but does not contribute significantly to the measured CBF because it has only a small blood content itself. The results lend support to this method of estimating CBF although formal validation by comparison with an established technique is needed.

Adult↗
PubMed1996

Activation of the electrocorticogram by propofol during surgery for epilepsy.

Propofol is used widely during general anaesthesia but there has been concern that it may be implicated in provoking seizure activity. We have investigated the effects of low-dose propofol on the electrocorticogram of anaesthetized patients undergoing surgery for medically intractable epilepsy. During continuous peroperative recording of the electrocorticogram, propofol was administered in 25 mg increments until burst suppression occurred. Activation of the electrocorticogram occurred in 17 of 20 patients. There was an increase in mean spike frequency in 16, extension of spike distribution in 15 and polyphasia in 13 patients. The mean dose of propofol required to cause burst suppression was 88.2 (range 25-175) mg. We conclude that at low doses, propofol caused activation of the electrocorticogram in epileptic patients but at higher doses burst suppression was induced.

Adolescent↗
PubMed1996

Vestibulospinal, reticulospinal and descending propriospinal nerve fibres in man.

The course and location of vestibulospinal, reticulospinal and descending propriospinal fibres in man are reported. The investigation was carried out on three patients with supraspinal lesions, four with transection of the spinal cord and 33 with anterolateral cordotomies. The lateral vestibulospinal tract at the medullospinal junction and in the first three cervical segments lies on the periphery of the spinal cord lateral to the anterior roots. It moves to the sulcomarginal angle in the remaining cervical segments. In the thoracic cord, it moves laterally, being traversed by the most lateral of the anterior roots. Reticulospinal fibres descend bilaterally in the spinal cord with a preponderance of ipsilateral fibres. Reticulospinal fibres in general do not form well-defined tracts, but are scattered throughout the anterior and lateral columns. They are intermingled with propriospinal fibres and with ascending and descending fibres of other systems. Most reticulospinal fibres move posterolaterally as they descend. It follows that fibres from the brainstem that enter the cord in the anterior column may be in the lateral column anterior to the lateral corticospinal tract at lower levels. Reticulospinal fibres within the lateral column lie anterior to the lateral corticospinal tract. They consist of scattered fibres between the lateral horn and the periphery, most of them in the medial two-thirds of the column. In addition, they are present in a more compact group, forming a triangle on transverse section on the periphery of the lateral column, immediately anterior to the lateral corticospinal tract. On the periphery of the anterior and anterolateral columns reticulospinal fibres descend as small groups or as a continuous band of fibres. The most medial of these reaches the sacral segments and is included in the sulcomarginal fasciculus. A compact group of fibres, shown previously to be central sympathetic fibres ending in the intermediolateral and intermediomedial cell columns, surrounds the lateral horn. They do not extend throughout the thoracic cord in all cases. Anterior to this group is another group of fibres lying on the anterolateral surface of the anterior horn. As these fibres were degenerating following a pontine lesion, they must be reticulospinal fibres. The fibres were not seen in all cases and they did not always reach the lowest thoracic segments. Reticulospinal fibres enter the grey matter in the zona intermedia and along the anterolateral and anterior surfaces of the anterior horns. Caudal to the cervical enlargement, the number of reticulospinal fibres decreases, and their place is taken by propriospinal fibres. But they are not totally replaced by the propriospinal fibres, for reticulospinal fibres continue down into the lowest sacral segments. Of the propriospinal fibres, the majority are short: descending fibres within the juxtagriseal layer are one to two segments long or less.

Adult↗
PubMed1996

Transmission-ratio distortion through F1 females at chromosome 11 loci linked to Om in the mouse DDK syndrome.

We determined the genotypes of > 200 offspring that are survivors of matings between female reciprocal F1 hybrids (between the DDK and C57BL/6J inbred mouse strains) and C57BL/6J males at markers linked to the Ovum mutant (Om) locus on chromosome 11. In contrast to the expectations of our previous genetic model to explain the "DDK syndrome, " the genotypes of these offspring do not reflect preferential survival of individuals that receive C57BL/6J alleles from the F1 females in the region of chromosome 11 to which the Om locus has been mapped. In fact, we observe significant transmission-ratio distortion in favor of DDK alleles in this region. These results are also in contrast to the expectations of Wakasugi's genetic model for the inheritance of Om, in which he proposed equal transmission of DDK and non-DDK alleles from F1 females. We propose that the results of these experiments may be explained by reduced expression of the maternal DDK Om allele or expression of the maternal DDK Om allele in only a portion of the ova of F1 females.

Animals↗
PubMed1996

The stoned locus of Drosophila melanogaster produces a dicistronic transcript and encodes two distinct polypeptides.

The stoned gene of Drosophila melanogaster is required for normal neuronal function in both adult and larva. We have identified DNA sequences that lie within a genetic region that is known to include the stoned gene and that also reveal restriction site variations in two stoned lethal mutants. This genomic region contains a single transcription unit coding for an approximately 8.4-kb transcript. The transcript is preferentially expressed in the head of adult flies. The isolation and sequencing of cDNA and genomic clones reveals that stoned appears to encode a dicistronic mRNA, although the possible existence of other forms of mRNA cannot be excluded. Antibody cross-reactivity shows that two proteins are translated from the stoned locus in vivo. Both open reading frames (ORFs) encode novel proteins. The protein encoded by the first ORF contains four tandemly repeated motifs, and one domain of the protein encoded by the second ORF shows similarity to a family of proteins (AP50s) associated with clathrin assembly protein complexes.

Amino Acid Sequence↗
PubMed1996

Homozygous and compound heterozygous mutations at the Werner syndrome locus.

The Werner syndrome (WS) is a rare autosomal recessive progeroid disorder. The Werner syndrome gene (WRN) has recently been identified as a member of the helicase family. Four distinct mutations were previously reported in three Japanese and one Syrian WS pedigrees. The latter mutation was originally described as a 4 bp deletion spanning a spliced junction. It is now shown that this mutation results in a 4 bp deletion at the beginning of an exon. Nine new WRN mutations in 10 additional WS patients, both Japanese and Caucasian, are described. These include three compound heterozygotes (one Japanese and two Caucasian). The new mutations are located all across the coding region.

Asian People↗