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Biomedical subjects

J Thompson

Publications and source records attributed to J Thompson.

At least 271 records · Page 15Linked to original sources
PubMed1997

Rapid isolation of genomic clones for individual members of human multigene families: identification and localisation of UBE2L4, a novel member of a ubiquitin conjugating enzyme dispersed gene family.

We describe a rapid, PCR-based, screening procedure for the isolation of human genomic clones in lambda bacteriophage, containing sequences coding for individual homologous members of a multigene family. The approach is based upon the identification, by dilution, of sub-pools of the genomic library that contain members of the gene family, prior to phage isolation. The presence of specific genes is established by PCR of aliquots of individually amplified library pools, using consensus primers and subsequent sequencing. We have used the approach to isolate a fourth member of the UBE2L gene family, UBE2L4, and located it on chromosome 19q13.1-->q13.2. This PCR-based approach to library screening has wider applicability in that it could be used to isolate alternate-spliced products from cDNA libraries.

Bacteriophage lambda↗
PubMed1997

Antimicrobial activity of viridiofungins.

A family of aminoacyl alkyl citrate compounds called viridiofungins, are novel squalene synthase inhibitors. The compounds have broad spectrum fungicidal activity but lack antibacterial activity. Although the compounds inhibit squalene synthase, the first committed step in ergosterol biosynthesis, results presented in this paper show that inhibition of fungal growth is not related to inhibition of ergosterol synthesis.

Antifungal Agents↗
PubMed1997

Surgical outpatients: challenges and responses.

BACKGROUND: Faced with upward pressure on costs from ageing populations and new technologies, those responsible for funding health care are seeking innovative ways of providing that care at lower cost. A common strategy is to shift care from the inpatient to the outpatient setting. This, taken with pressure for greater accountability and improved training, is creating great challenges for those responsible for organizing outpatient care. This paper seeks to review these challenges and the various responses to them. METHODS: A critical review of literature on the changing role of outpatient care, with an emphasis on the current situation in the United Kingdom. RESULTS: Many diverse responses have been developed to address the changing nature of outpatient care. These have certain features, including the recognition that clinicians have the ability to initiate, rather than simply react to change, and an appreciation of the value of clear and definable objectives for outpatient care. They range from discrete interventions addressing a single concern to wholesale restructuring of the system of care, such as one-stop clinics. CONCLUSION: There is now considerable evidence on what can and should be done to improve the existing system of outpatient care.

Ambulatory Surgical Procedures↗
PubMed1997

Unusual neck masses secondary to jugular venous abnormalities: case report and discussion.

Thrombosis of the lateral sinus/proximal jugular vein and jugular venous ectasia are infrequent but not uncommon neck masses. Lateral sinus thrombosis was well described in the preantibiotic era, but modern-day surgeons may not be familiar with this entity. Failure to diagnose a neck mass due to jugular vein thrombosis may have deadly consequences. Jugular vein ectasia, which is innocuous, has been mistaken for laryngocele, cystic hygroma, as well as other vascular lesions. However, the management of jugular vein ectasia, which is thought to be caused by incompetence of the bicuspid jugular venous valve, is conservative. We present a case illustrating a neck mass arising from the internal jugular vein with a discussion of jugular venous pathology.

Adolescent↗
PubMed1997

Differences in CD34+ cell subpopulations between human bone marrow and "mobilized" peripheral blood as determined with counterflow centrifugal elutriation.

Engineering of hematopoietic progenitor cells (HPCs) from bone marrow (BM) or "mobilized" peripheral blood (MoPB) is becoming increasingly important. Counterflow centrifugal elutriation (CCE) has been used to separate cells on the basis of their size. In this study, CCE was applied to evaluate BM and MoPB for differences in their HPC populations. Using a standard 4-mL elutriation chamber at 2300 rpm, CD34+ cells from BM peaked at a flow rate of 19 mL/minute, with 85% of all CD34+ cells recovered from fractions 15-22 mL/minute. The CD34+ cells from MoPB, mobilized with chemotherapy and granulocyte colony-stimulating factor (G-CSF), peaked at 22 mL/minute, with 90% of all CD34+ cells recovered from fraction 19-26 mL/minute. Colony-forming cells (colony-forming units granulocyte/macrophage [CFU-GM] + burst-forming unit-erythroid [BFU-E] + multipotent colony-forming units [CFU-GEMMs]) followed the distribution of CD34+ cells very closely, also with a shift to higher flow-rates for MoPB compared with BM. The lower flow-rate fractions of both BM and MoPB contained an increased proportion of CD34+ cells that did not express HLA-DR and/or CD38 on their surface, suggesting that the earliest CD34+ cells were enriched in the low-flow rate fractions. Although CFU-GMs, BFU-Es, and CFU-GEMMs from BM all peaked in the same fraction (19 mL/minute), high-proliferative potential colony-forming cells (HPP-CFCs) were concentrated in fraction 17 mL/minute, indicating that these earlier progenitor cells were slightly smaller. With MoPB, HPP-CFCs did not appear to be smaller than BFU-Es or CFU-GEMMs. CCE appears to be an attractive method for separating HPCs from BM or MoPB into populations of different maturity. Differences in CD34+ cell populations between BM and MoPB may help explain the differences in repopulation kinetics observed after transplantation.

Antigens, CD34↗
PubMed1997

Inhaled nitric oxide in the management of cardiopulmonary disorders in infants and children.

The administration of NO has become an important and effective therapy in the clinical management of pulmonary hypertension associated with cardiopulmonary disorders in infants and children. It is likely to become a routine therapy in the treatment of PPHN, although dosing and timing strategies, early indicators of treatment failure, and long-term outcomes are not completely understood. The use of NO has also been beneficial in the evaluation and management of pulmonary hypertension associated with congenital heart disease. The role of NO in the management of pediatric ARDS holds promise, although further clinical trials are needed. Additional research should also be directed toward the use of NO in preterm infants and those born with CDH. Future endeavors may also include the use of NO in the evaluation and management of asthma.

Administration, Inhalation↗
PubMed1997

Delayed ulcer recurrence after gastric resection: a new postgastrectomy syndrome?

Recurrent ulceration following gastrectomy for peptic ulcer disease typically occurs within the first several years postoperatively. Since 1990, we have managed 20 patients who had undergone previous gastrectomy for peptic ulcer and developed ulcer recurrence more than 10 years postoperatively. Mean age at recurrence was 64 years, and the average time from original surgery to recurrent ulceration was 21 years (range, 10-36 years). All patients had undergone vagotomy and antrectomy (17 patients) or subtotal gastrectomy (3 patients). Presenting symptoms included gastric outlet obstruction (70%) and bezoar formation (60%). Endoscopic findings in this group of patients included a stenotic gastric outlet (70%) and marginal ulcerations (80%). Thirteen of 15 patients tested (87%) were Helicobacter pylori positive. Reoperation included partial resection of the gastric pouch and exploration for persistent vagus nerve. Twelve patients underwent Roux-en-Y reconstruction, whereas eight patients had Bilroth II reconstruction. Three of the latter group also had Braun enteroenterostomy performed. Good to excellent clinical results were obtained in 80 per cent of patients. The four patients with poor outcomes shared the following characteristics: 1) H. pylori-positive status, 2) presence of a preoperative bezoar, 3) Roux-en-Y reconstruction. Our current approach is to avoid Roux-en-Y construction in favor of Braun enteroenterostomy. Further prospective analysis of long-term postgastrectomy patients is needed to determine whether this clinical picture represents a new postgastrectomy syndrome.

Adult↗
PubMed1997

Efficacy of systemic administration of irinotecan against neuroblastoma xenografts.

The efficacy of the topoisomerase I inhibitor 7-ethyl-10-(4-[1-piperidino]-1-piperidino)-carbonyloxy-camptotheci n (irinotecan, CPT-11) has been examined against a panel of six independently derived neuroblastoma xenografts. Intensive courses of therapy, where irinotecan was administered i.v. daily 5 days per week for two consecutive weeks [(dx5)2; defined as 1 cycle], were compared to more protracted low-dose schedules where cycles were repeated every 21 days for a total of three courses ¿abbreviated [(dx5)2]3¿. When administered (dx5)2 for a single cycle, the maximum tolerated daily dose was 40 mg/kg. Irinotecan induced a high frequency of complete regressions (CRs) in four of the six lines examined; however, most tumors achieving CR regrew during the period of observation (12 weeks). Furthermore, there was no advantage in high-dose regimens as compared to low dose (10 mg/kg) on the same schedule. Protracted schedules of administration, where three courses of therapy were given at 21-day intervals ¿[(dx5)2]3¿ i.v. were examined at 10 and 5 mg/kg/dose. Even at the lower dose level, irinotecan caused 100% CR in all tumor lines that were maintained at 12 weeks. To determine the minimum dose levels required to induce objective regressions of neuroblastoma xenografts, decreasing doses were examined using the [(dx5)2]3 i.v. schedule. At 2.5 mg/kg/dose, >90% of NB-1643, NB-1691, NB-1382.2, and NB-EB xenografts demonstrated CR, whereas at 1.25 mg/kg/dose, all six tumor lines evaluated demonstrated objective regressions (>/=50% volume reduction), with a high frequency of CRs in four tumor lines. The 10-hydroxy-7-ethyl CPT lactone single-day systemic exposure measured with the minimum dose (2.5 mg/kg) associated with complete response was 198, 257, and 228 ng.h/ml for mice bearing NB-1643, NB-1691, and NB-EB tumors, respectively. These results indicate that childhood neuroblastoma xenografts are highly sensitive to irinotecan given by parenteral administration, and that efficacy is schedule dependent.

Animals↗
PubMed1996

Coordinate expression of splice variants of the murine pregnancy-specific glycoprotein (PSG) gene family during placental development.

The human and murine pregnancy-specific glycoprotein (PSG) gene families encode a large number of closely related proteins which are abundantly expressed in the fetal trophoblast and secreted into the maternal circulation. Although the presence of a well conserved tripeptide sequence His or Arg-Gly-Asp or Glu or Lys (H/RGD/E/K) similar to the RGD motif found in extracellular matrix proteins hints towards a possible interaction with integrin-type receptors, the function of this group of proteins related to the carcinoembryonic antigen family is still unknown. It is also not clear whether the various members of the PSG family exert the same function. Here we describe the cloning of two splice variants of Cea4 (Cea4a, Cea4b), a murine PSG family member, which lacks the RGD-related consensus motif. Cea4a, like most of the other rodent PSG members, is composed of three immunoglobulin (Ig) variable-like domains (N1-N3) and and one Ig constant-like domain (A). In contrast, Cea4b lacks the N2 domain (N1N3A), demonstrating for the first time that PSG isoforms produced by alternative splicing also exist in mice. The mRNAs coding for Cea4a and Cea4b exhibit the same expression kinetics during placental development as found for two other murine PSGs, Cea2 and Cea3, which contain the RGD-like motif. Expression starts after day 12.5 of embryonic development (E12.5) and maximum steady-state levels are reached around E15.5-E17.5 as determined by RNase protection analyses. At E17.5, PSG transcripts can be detected exclusively in the spongiotrophoblast of the placenta. In addition, PCR analyses revealed that Cea2, Cea3, and Cea4 transcripts are also found in RNA from a pool of embryos (E12-E15) but are absent from a number of adult tissues tested (kidney, lung, testis, ovary, liver, brain, thymus, heart, spleen). These results indicate that the various PSG isoforms exert their function(s) at the same time during placental and embryonic development.

Alternative Splicing↗
PubMed1996

FOS expression induced by interleukin-1 or acute morphine treatment in the rat hypothalamus is attenuated by chronic exposure to morphine.

Interleukin-1 (IL-1) is a cytokine involved in a variety of biological activities. It has been hypothesized that the immunomodulatory effects of IL-1 are the result of both direct action on immune cells and indirect action on a regulatory cascade mediated through the hypothalamus. Chronic exposure to substances of abuse, such as morphine, appears to modulate immunoresponsiveness by mechanisms not yet defined. The expression of FOS, the protein product of the c-fos proto-oncogene, has been widely used as an anatomical marker for monitoring neuronal activity. We have previously shown that acute treatment with either morphine or IL-1 induces FOS immunoreactivity in the rat brain, including the paraventricular (PVN) and supraoptic (SON) nuclei of the hypothalamus. In this study, using immunocytochemical staining of FOS, we demonstrate that chronic exposure to morphine attenuates the cellular responsiveness to IL-1 and to morphine in the PVN and SON, whereas pretreatment with naloxone, an opiate receptor antagonist, does not reverse the effect of IL-1 on FOS expression. The results not only confirm that the PVN and SON are neuroanatomical sites where the actions of both morphine and IL-1 converge, but also indicate that chronic exposure to morphine may desensitize the cellular response involved in hypothalamic functions through an IL-1-dependent pathway.

Animals↗
PubMed1996

Catheterisation: extending the scope of practice.

Continuing our series on issues surrounding the Scope of Professional Practice, this article describes the nurse's role in male and suprapubic catheterisation. It relates to UKCC Professional Development Categories: Care enhancement and Reducing risk.

Cystostomy↗
PubMed1996

Identification of lysine residues required for signal-induced ubiquitination and degradation of I kappa B-alpha in vivo.

Activation of transcription factor NF-kappaB involves signal-induced degradation of the protein inhibitor IkappaB-alpha and release of NF-kappaB which translocates to the nucleus where it influences transcription of responsive genes. Although multiple regions of IkappaB-alpha are involved in this process, the N-terminal region of the protein has been identified as a regulatory region that is required for signal induced phosphorylation and degradation. The sensitivity of IkappaB-alpha degradation to peptide aldehydes which inhibit components of the proteasome and the detection of ubiquitinated forms of IkappaB-alpha indicate that IkappaB-alpha is degraded by the ubiquitin-proteasome pathway. To identify lysine residues that represent the sites of ubiquitin addition, a series of lysine to arginine mutations were introduced into IkappaB-alpha and the mutant proteins tested for their ability to function in vivo. Exposure of COS7 cells, cotransfected with IkappaB-alpha and a TNF-responsive NF-kappaB reporter gene, resulted in stimulation of reporter activity as a consequence of IkappaB-alpha degradation. In contrast, this effect was drastically reduced when an IkappaKB-alpha mutant carrying serine to alanine changes at amino-acids, 32 and 36, which blocks both signal-induced phosphorylation and ubiquitin conjugation of the protein, was co-transfected with the reporter gene. Likewise, a mutant form of IkappaB-alpha containing lysine to arginine changes at positions 21 and 22 (K21R, K22R) severely reduces TNF-induced activation of the NF-kappaB-dependent reporter gene. Examination of the metabolism of mutant IkappaB-alpha molecules reveals that, while the K21R, K22R mutant inhibits the DNA-binding activity of NF-kappaB and undergoes signal induced phosphorylation, it is neither ubiquitinated nor degraded in response to TNF. Thus, it is likely that after signal-induced phosphorylation Of IkappaB-alpha on serine residues 32 and 36, lysine residues 21 and 22 are major sites of ubiquitin ligation which target the protein for rapid degradation by the proteasome.

Amino Acid Sequence↗
PubMed1996

Role of IkappaBalpha ubiquitination in signal-induced activation of NFkappaB in vivo.

In unstimulated cells, the transcription factor NF-kappaB is held in the cytoplasm in an inactive state by the inhibitor protein IkappaBalpha. Stimulation of cells results in rapid phosphorylation and degradation of IkappaBalpha, thus releasing NF-kappaB, which translocates to the nucleus and activates transcription of responsive genes. Here we demonstrate that in cells where proteasomal degradation is inhibited, signal induction by tumor necrosis factor alpha results in the rapid accumulation of higher molecular weight forms of IkappaBalpha that dissociate from NF-kappaB and are consistent with ubiquitin conjugation. Removal of the high molecular weight forms of IkappaBalpha by a recombinant ubiquitin carboxyl-terminal hydrolase and reactivity of the immunopurified material with a monoclonal antibody specific for ubiquitin indicated that IkappaBalpha was conjugated to multiple copies of ubiquitin. Western blot analysis of immunopurified IkappaBalpha from cells expressing epitope-tagged versions of IkappaBalpha and ubiquitin revealed the presence of multiple copies of covalently bound tagged ubiquitin. An S32A/S36A mutant of IkappaBalpha that is neither phosphorylated nor degraded in response to signal induction fails to undergo inducible ubiquitination in vivo. Thus signal-induced activation of NF-kappaB involves phosphorylation-dependent ubiquitination of IkappaBalpha, which targets the protein for rapid degradation by the proteasome and releases NF-kappaB for translocation to the nucleus.

Amino Acid Sequence↗
PubMed1996

Affinity maturation of a high-affinity human monoclonal antibody against the third hypervariable loop of human immunodeficiency virus: use of phage display to improve affinity and broaden strain reactivity.

The present study set out to investigate whether phage display could be used to improve the properties of a high-affinity human monoclonal antibody directed against the third hypervariable loop (V3 loop) of human immunodeficiency virus (HIV). The aim was to increase affinity through slowing the dissociation rate (off-rate constant of koff), whilst retaining the ability of this antibody to bind diverse V3 loop sequences. When reformatted as a scFv, the antibody fragment retained the properties of the parental IgG, including the ability to neutralise virus. Heavy and light chains were sequentially replaced with repertoires of variable domains from non-immunised human donors followed by selection on biotinylated synthetic peptide. All selected variants derived from the same germline as the parental antibody. Variants of the light chain provided little if any improvement, whereas two residue changes in VHCDR2 and one in VHFR3 resulted in a reduced koff from gp120 protein of the MN strain (MNgp120) and synthetic V3 loop peptides as measured by surface plasmon resonance using the BIAcore instrument (Pharmacia Biosensor). VHCDR3 was modified using synthetic oligonucleotides and several clones with reduced koff identified, a number of different substitutions occurring at a single residue position. The residues in the heavy chain identified as reducing koff were simultaneously randomised by site-directed mutagenesis, resulting in scFv variants with koff slowed up to sevenfold. Far from compromising recognition of variant loops, binding to these sequences was improved; the koff from synthetic peptides modelled on V3 loop variants being slowed to a degree similar to that observed with MNgp120. All four changes were located towards either extremes of CDRs 2 and 3, suggesting that the mechanism of improvement may be one of alternation of loop conformation. This work illustrates that phage display can be used to tailor the properties of a therapeutic monoclonal antibody in a predefined fashion.

Amino Acid Sequence↗