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Biomedical subjects

S G Taylor

Publications and source records attributed to S G Taylor.

At least 19 recordsLinked to original sources
PubMed2001

The cytoplasmic tail of alpha 1,2-fucosyltransferase contains a sequence for golgi localization.

The Golgi apparatus has a central role in the glycosylation of proteins and lipids. There is a sequential addition of carbohydrates by glycosyltransferases that are distributed within the Golgi in the order in which the glycosylation occurs. The mechanism of glycosyltransferase retention is considered to involve their transmembrane domains and flanking regions, although we have shown that the cytoplasmic tail of alpha1,2-fucosyltransferase is important for its Golgi localization. Here we show that the removal of the alpha1,2-fucosyltransferase cytoplasmic tail altered its function of fucosylation and its localization site. When the tail was removed, the enzyme moved from the Golgi to the trans Golgi network, suggesting that the transmembrane is responsible for retention and that the cytoplasmic tail is responsible for localization. The cytoplasmic tail of alpha1,2-fucosyltransferase contains 8 amino acids (MWVPSRRH), and mutating these to alanine indicated a role for amino acids 3 to 7 in localization with a particular role of Ser(5). Mutagenesis of Ser(5) to amino acids containing an hydroxyl (Tyr and Thr) demonstrated that the hydroxyl at position 5 is important. Thus, the cytoplasmic tail, and especially a single amino acid, has a predominant role in the localization and thus the function of alpha1,2-fucosyltransferase.

Amino Acid Sequence↗
PubMed2001

Effects of centrally administered orexin-B and orexin-A: a role for orexin-1 receptors in orexin-B-induced hyperactivity.

RATIONALE: Orexin-A and orexin-B are hypothalamic neuropeptides derived from a 130-amino acid precursor, prepro-orexin, and are potent agonists at both the orexin-1 (OX1) and orexin-2 (OX2) receptors. Orexin-A has been ascribed a number of in vivo functions in the rat after intracerebroventricular (ICV) administration, including hyperphagia, neuroendocrine modulation and a role in the regulation of sleep-wake function. The in vivo role of orexin-B is not as clear. OBJECTIVES: To investigate the behavioural, endocrine and neurochemical effects of orexin-B in in-vivo tests. In a number of experiments, these effects were compared with those of orexin-A. METHODS: Experiments were carried out in male, Sprague-Dawley rats with a guide cannula directed towards the lateral ventricle. The effects of orexin-B (ICV) upon grooming behaviour were compared with those of orexin-A. The effects of orexin-B upon the motor activity response to both novel and familiar environments were assessed in an automated activity monitor. Orexin-B was tested upon startle reactivity and body temperature. Further, plasma hormones and [DOPAC+ HVA]/[DA] and [5-HIAA]/[5-HT] ratios in six brain areas were measured 40 min post-orexin-B or orexin-A. RESULTS: The clearest behavioural response to orexin-B was increased motor activity in both novel and familiar environments. Orexin-B-induced hyperactivity was blocked by an OX1 receptor antagonist, SB-334867-A, implicating OX1 receptors in this behavioural response. In common with orexin-A, orexin-B reduced plasma prolactin and failed to influence startle reactivity. However, in contrast with orexin-A, orexin-B increased head grooming but failed to cause a robust whole body grooming response or increase plasma corticosterone levels. Further, orexin-B, but not orexin-A, increased plasma TSH and increased hypothalamic and striatal [5-HIAA]/[5-HT] ratios. CONCLUSIONS: The present study has demonstrated a number of behavioural, neuroendocrine and neurochemical effects of orexin-B that distinguish it from orexin-A. Further, we have demonstrated a role for OX1 receptors in the actions of orexin-B upon motor activity.

Animals↗
PubMed2001

Does contraction of mesh following tension free hernioplasty effect testicular or femoral vessel blood flow?

Prosthetic mesh can contract by 20-75% of its original size within ten months after implantation. We set out to determine whether this contraction has any effect on testicular or femoral vessel blood flow following open or laparoscopic hernia repair. Twenty patients who underwent mesh repair of a primary unilateral inguinal hernia repair by Open (10) or Laparoscopic (10) methods a median of 3 years previously were investigated by ultrasound to determine the haemodynamic characteristics of the testis and femoral vessels. There was no significant difference in testicular blood flow, volume or echogenicity between the different types of repair or the contralateral side. The vertical and transverse dimensions of the femoral artery and vein were similar in all groups as was blood flow. Mesh contraction following inguinal hernioplasty does not adversely affect the testis or femoral vessels and can be used safely for both anterior and preperitoneal approaches.

Adult↗
PubMed2001

Central effects of urotensin-II following ICV administration in rats.

RATIONALE: Urotensin-II (U-II) has recently been identified as an agonist for the G-protein-coupled receptor, GPR14. Detection of both U-II and GPR14 mRNA in the brain and spinal cord is consistent with a role for U-II in the CNS. However, the effects of central administration of U-II in rodents have not been reported previously. OBJECTIVES: To determine the localisation of GPR14 mRNA in rat tissues and to investigate the behavioural and endocrine effects of human U-II (hU-II) following intracerebroventricular (ICV) administration in rats. METHODS: Experiments were carried out in male Sprague-Dawley rats. Expression of GPR14 mRNA in rat brain was determined by semi-quantitative RT-PCR. Effects of hU-II on general behaviours were assessed by an observer and the motor activity response was measured by an automated activity monitor. Plasma hormones and [DOPAC + HVA]/[DA] and [5-HIAA]/[5-HT] ratios in five brain areas were measured 20 min post-hU-II (ICV). RESULTS: GPR14 mRNA expression was found in whole brain tissue and in all CNS regions tested. GPR14 mRNA expression was also detected in the periphery; highest levels were found in the heart. Following ICV administration, hU-II (3-10 micrograms ICV) increased rearing and grooming, and increased motor activity in a familiar environment. Further, hU-II increased plasma prolactin and TSH but did not affect levels of corticosterone. hU-II had no effects on dopamine or 5-HT levels or their metabolites in the frontal cortex, hippocampus, hypothalamus, striatum and nucleus accumbens. CONCLUSIONS: These data provide further insight into the distribution of GPR14 mRNA within the CNS and show for the first time that hU-II causes marked behavioural and endocrine effects.

Animals↗
PubMed2001

Use of a genetic marker to examine genetic interaction among subpopulations of pink salmon (Oncorhynchus gorbuscha).

In 1979 and 1981, a genetic marker was bred into one of the five identifiable subpopulations of pink salmon [Oncorhynchus gorbuscha (Walbaum)] in the Auke Lake drainage in Southeast Alaska. As a result of the marking effort, the frequencies of two malate dehydrogenase (MDH-B1, 2*) alleles were changed in the marked subpopulation, but not in other subpopulations that spawn at different times or places. Between 1983 and 1989, the marker allele frequencies were monitored in many of these subpopulations and in early- and late-run pink salmon spawning in nearby Waydelich Creek, located approximately 1 km away. Changes in allele frequencies at MDH-B1, 2*, used to obtain direct estimates of average migration rates (m) from the marked to the unmarked subpopulations, revealed little or no introgression into early subpopulations or into nearby Waydelich Creek. Moreover, spatially distinct late-run Auke Creek subpopulations were not immediately overrun by the more abundant marked subpopulation. These observations suggest that genetic isolation exists between temporally distinct spawning runs and that small temporal and spatial (or ecological) differences contribute to population structure. These observations should be considered in taking actions that affect conservation and harvest management or extensive culture of salmonids.

Alleles↗
PubMed2001

A theory of dependent-care: a corollary theory to Orem's theory of self-care.

Dependent-care has its origins in people's requirements for regulatory care. The foundations for dependent-care are found in the ability of individuals to provide their required care. First introduced as a corollary to self-care, this work emerged through a process of reading and discussion. Models that support the theory of dependent-care are identified. Premises are stated. There is elaboration of the conceptualizations representing the work that has been done. There are still elements that need further development, such as specifying the enabling abilities of dependent-care agency and verifying and formalizing the various elements presented.

Adult↗
PubMed2001

Head and neck cancer.

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Clinical Trials as Topic↗
PubMed2000

Pharmacological actions of a novel, high-affinity, and selective human dopamine D(3) receptor antagonist, SB-277011-A.

SB-277011-A (trans-N-[4-[2-(6-cyano-1,2,3, 4-tetrahydroisoquinolin-2-yl)ethyl]cyclohexyl]-4-quinolininecarboxamide), is a brain-penetrant, high-affinity, and selective dopamine D(3) receptor antagonist. Radioligand-binding experiments in Chinese hamster ovary (CHO) cells transfected with human dopamine D(3) or D(2 long) (hD(3), hD(2)) receptors showed SB-277011-A to have high affinity for the hD(3) receptor (pK(i) = 7.95) with 100-fold selectivity over the hD(2) receptor and over 66 other receptors, enzymes, and ion channels. Similar radioligand-binding data for SB-277011-A were obtained from CHO cells transfected with rat dopamine D(3) or D(2). In the microphysiometer functional assay, SB-277011-A antagonized quinpirole-induced increases in acidification in CHO cells overexpressing the hD(3) receptor (pK(b) = 8.3) and was 80-fold selective over hD(2) receptors. Central nervous system penetration studies showed that SB-277011-A readily entered the brain. In in vivo microdialysis studies, SB-277011-A (2. 8 mg/kg p.o.) reversed the quinelorane-induced reduction of dopamine efflux in the nucleus accumbens but not striatum, a regional selectivity consistent with the distribution of the dopamine D(3) receptor in rat brain. SB-277011-A (2-42.3 mg/kg p.o.) did not affect spontaneous locomotion, or stimulant-induced hyperlocomotion. SB-277011-A (4.1-42.2 mg/kg p.o.) did not reverse prepulse inhibition deficits in apomorphine- or quinpirole-treated rats, but did significantly reverse the prepulse inhibition deficit in isolation-reared rats at a dose of 3 mg/kg p.o. SB-277011-A (2.5-78. 8 mg/kg p.o.) was noncataleptogenic and did not raise plasma prolactin levels. Thus, dopamine D(3) receptor blockade produces few of the behavioral effects characteristic of nonselective dopamine receptor antagonists. The effect of SB-277011-A on isolation-induced prepulse inhibition deficit suggests that blockade of dopamine D(3) receptors may benefit the treatment of schizophrenia.

Animals↗
PubMed2000

Orem's self-care deficit nursing theory: its philosophic foundation and the state of the science.

There is a preponderance of descriptive studies, ranging from those using a simple descriptive correlational approach to multivariate approaches. Only one study is clearly identified as an experimental study (Moore, 1987) and two clearly identified as replication studies (Lenatsch, 1999; Schott-Baer, Fisher, & Gregory, 1995). Fewer than half make clear links between the variables being examined and situations of nursing practice; that is, they examine elements of the theory of self-care without making the link to nursing practice an explicit part of the study. While this work is increasing our knowledge about self-care (Stage II), further work needs to be done to put the results of these in the context of nursing practice as in Stages III, IV, or V. Most of the studies reviewed are Stage II and provide an enhanced or broader description of an element or component of the theory, empirically describing the relationships between or among age, gender, self-care actions, disease, and so forth. These studies add to our understanding of existing and known or proposed relationships within the extant theory. The majority of studies examine self-care and/or self-care deficits. There are many studies but little evidence that sustained research programs are developing and expanding the theory. The bricks are piling up around the framework, but only a few scholars are working on building the walls. These programs of research are occurring in universities where a critical mass of interested scholars and students can be found. The use of theoretical language is sometimes imprecise and at other times inaccurate. Valid new terms are introduced but the relationship to existing theoretical constructs is not always explicit. There is little critical review of research in the literature. Ongoing dialog among scholars is minimal. There is a need for nurse scholars to come together and to engage in such a dialogue to enhance the work. Given the relatively short history of nursing research and, more importantly, the conduct of nursing theory-based research, the number and quality of the work being conducted is quite remarkable. There has been a substantial amount of work produced and the quality of it has improved over time. Orem has provided nurse researchers with a theoretical system comprising an ontological structure, related epistemology, and numerous models that give direction to scholarly efforts. Scholars using this theoretical system would be well-advised to use these in conceptualizing and interpreting their work.

Humans↗
PubMed1999

Development of a protocol for the automated analysis of amino acids in brain tissue samples and microdialysates.

An automated precolumn derivatisation method has been developed for the measurement of fourteen amino acids in brain tissue and microdialysate samples. The method involves labelling amino acids with naphthalene-2,3-dicarboxaldehyde (NDA) in the presence of cyanide (CN-). The resulting highly stable N-substituted 1-cyanobenz[f]isoindole (CBI) derivatives were separated using a binary gradient elution profile and detected fluorometrically. The order of elution of the derivatised amino acids was confirmed by using liquid chromatography with fluorescence and mass spectrometric detection in tandem. Linear calibration plots were obtained for all amino acids in the range studied (0.2-12.5 microM). The limit of detection for CBI derivatives of amino acids was in the range 5-20 fmol (S/N=2) using a 5 microl injection volume. The method has been used for the measurement of amino acids in microdialysates from rat brain and tissue homogenates from different regions of mouse brain.

Amino Acids↗
PubMed1999

Orexin A activates locus coeruleus cell firing and increases arousal in the rat.

The localization of orexin neuropeptides in the lateral hypothalamus has focused interest on their role in ingestion. The orexigenic neurones in the lateral hypothalamus, however, project widely in the brain, and thus the physiological role of orexins is likely to be complex. Here we describe an investigation of the action of orexin A in modulating the arousal state of rats by using a combination of tissue localization and electrophysiological and behavioral techniques. We show that the brain region receiving the densest innervation from orexinergic nerves is the locus coeruleus, a key modulator of attentional state, where application of orexin A increases cell firing of intrinsic noradrenergic neurones. Orexin A increases arousal and locomotor activity and modulates neuroendocrine function. The data suggest that orexin A plays an important role in orchestrating the sleep-wake cycle.

Animals↗
PubMed1999

5-CT stimulation of adenylyl cyclase activity in guinea-pig hippocampus: evidence for involvement of 5-HT7 and 5-HT1A receptors.

1. A number of compounds, including the selective 5-HT7 receptor antagonist SB-258719, were investigated for their effect on [3H]-5-carboxamidotryptamine (5-CT) radioligand binding and 5-CT-stimulated adenylyl cyclase activity in guinea-pig hippocampal membranes, in order to confirm the presence of functionally coupled 5-HT7 receptors in this tissue. 2. The [3H]-5-CT radioligand binding profile was consistent with binding predominantly to 5-HT7 receptors. The affinity of SB-258719 (pKi 7.2+/-0.1) was similar to its reported human 5-HT7 receptor affinity. 3. In the adenylyl cyclase functional assay, 5-CT was a potent and full agonist compared to 5-HT, whereas 8-hydroxy-dipropylaminotetralin (8-OH-DPAT) was a partial agonist (intrinsic activity 0.4+/-0.1). The rank order of potency for agonists (5-CT>5-HT approximately 8-OH-DPAT) was consistent with activation of 5-HT7 receptors. SB-258719 (5 microM) and methiothepin (1 microM) surmountably antagonized the response to 5-CT, consistent with competitive antagonism. The pKB for SB-258719 (7.2+/-0.1) was in good agreement with its reported antagonist potency at the human cloned 5-HT7 receptor. 4. In the functional assay, WAY-100635 (100 nM) and cyanopindolol (1 microM) induced a biphasic 5-CT response curve, consistent with selective antagonism of a component of the response to 5-CT. The estimated pKB values for WAY-100635 and cyanopindolol (9.6 and 8.4 respectively) were in good agreement with their reported 5-HT1A receptor affinities. 5. The data are consistent with the presence of 5-HT7 receptors in guinea-pig hippocampus which are positively coupled to adenylyl cyclase. In addition, 5-HT7 receptor-mediated stimulation of adenylyl cyclase activity in this tissue appears to be augmented by a mechanism involving 5-HT1A receptor activation.

Adenylyl Cyclases↗
PubMed1999

Chronic groin sepsis following tension-free inguinal hernioplasty.

BACKGROUND: Chronic groin sepsis requiring mesh removal is said to be a rare complication of tension-free inguinal hernioplasty. The aim of this study was to determine the number of surgeons performing tension-free inguinal hernioplasty in the West of Scotland and assess the frequency with which chronic groin sepsis was encountered. METHODS: A questionnaire was sent to all consultant surgeons performing inguinal hernia repair in the region and follow-up of patients with chronic groin sepsis following tension-free inguinal hernioplasty was undertaken. RESULTS: Of 80 consultants who replied to the questionnaire, 79 were performing tension-free hernioplasty. Of these, 76 were performing only open repairs while three were also undertaking laparoscopic repairs. Sixteen consultants reported 20 patients with groin sepsis after mesh repair. Twelve patients were traced; eight had chronic sinuses and four had groin abscesses. The median interval between repair and presentation was 4 months (range from 2 weeks to 39 months). All have required complete (11 patients) or partial (one) removal of mesh to resolve the symptoms. CONCLUSION: Tension-free inguinal hernioplasty has become the operation of choice for surgeons in the region. Chronic groin sepsis may be more frequent than reported previously. Complete removal of mesh is required to treat this condition.

Adult↗
PubMed1999

Severe cardiotoxicity during 5-fluorouracil chemotherapy: a case and literature report.

The chemotherapeutic agent 5-fluorouracil (5-FU) is a widely accepted part of many cancer treatment protocols. Its cardiotoxic potential is known, but considered uncommon and usually not life threatening, although some cases of severe cardiotoxicity related to 5-FU have been reported. The pathogenesis of cardiotoxicity caused by 5-FU is not clear. We report a case of sudden onset of severe cardiac failure, without ischemic symptoms or signs, during 5-FU treatment with serious consequences, in a previously healthy 23-year-old patient with squamous cell carcinoma of the tongue. Endomyocardial biopsy showed proliferation of the sarcoplasmic reticulum with marked vacuolization, similar to that found with doxorubicin cardiotoxicity. Because 5-FU cardiotoxicity is unpredictable and can have potentially fatal consequences, it requires, in our opinion, further clarification. With this well-documented case, including an endomyocardial biopsy, we hope to encourage additional efforts to investigate the pathophysiologic mechanisms of 5-FU cardiotoxicity.

Adult↗
PubMed1999

Theoretical and empirical description of adult couples' collaborative self-care systems.

Couples' collaborative care systems wherein work of self-care is shared are described from the perspective of Orem's nursing theory. Couples (N = 108) completed two forms of the Self-As-Carer Inventory: their perception of their own and of their partner's self-care agency. Each completed the Couple Form of the Family Adaptability and Cohesion Evaluation Scales and self-reports of health at this moment and of health in general. The person identified by the couple as having more caregiving responsibilities completed the Caregiver Reciprocity Scale. Stepwise multiple regression yielded a three-variable model (cohesion, dyad gender, and health now), which explained 27% of the variance of collaborative care system score. A collaborative care system model is proposed.

Adaptation, Psychological↗