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Biomedical subjects

A Hill

Publications and source records attributed to A Hill.

At least 19 recordsLinked to original sources
PubMed1996

A conserved domain of the viviparous-1 gene product enhances the DNA binding activity of the bZIP protein EmBP-1 and other transcription factors.

The maize VP1 protein is a seed-specific regulator of gene expression that effects the expression of a subset of abscisic acid (ABA)-regulated genes that are expressed during the maturation program of the seed. In addition, VP1 has pleiotropic effects on seed development that are not related to ABA. In transient expression assays, VP1 has been shown to transactivate gene expression through at least two distinct promoter elements: the G boxes from the ABA-inducible wheat Em gene and the SphI box from the maize C1 gene. We have investigated how VP1 can transactivate gene expression through diverse promoter elements by analyzing its association in vitro with EmBP-1, a factor that binds the Em promoter. We demonstrate that VP1 can greatly enhance the DNA binding activity of EmBP-1 in a gel retardation assay. This enhancing activity has also been observed on transcription factors as diverse as Opaque-2, Max, Sp1, and NF-kappaB. Deletion of a small but highly conserved region (BR2) in VP1 eliminates the enhancement in vitro as well as the ability of VP1 to transactivate Em gene expression in a transient expression assay. A 40-amino acid fragment from VP1 sandwiched between the maltose-binding protein and LacZ can confer the enhancement function to this fusion protein in vitro. A weak and relatively nonspecific interaction between BR2 and DNA is demonstrated by UV cross-linking. The in vitro properties we observe for VP1 might explain the regulatory effects of VP1 on a diverse set of genes and why mutations in the vp1 locus have pleiotropic effects.

Base Sequence↗
PubMed1996

Changes in plasma HIV-1 RNA and CD4+ lymphocyte counts and the risk of progression to AIDS. Veterans Affairs Cooperative Study Group on AIDS.

BACKGROUND: Clinical trials of antiretroviral drugs can take years to complete because the outcomes measured are progression to the acquired immunodeficiency syndrome (AIDS) or death. Trials could be accelerated by the use of end points such as changes in CD4+ lymphocyte counts and plasma levels of human immunodeficiency virus type 1 (HIV-1) RNA and beta 2-microglobulin, but there is uncertainty about whether these surrogate measures are valid predictors of disease progression. METHODS: We analyzed data from the Veterans Affairs Cooperative Study on AIDS, which compared immediate with deferred zidovudine therapy. Patients' plasma levels of HIV-1 RNA and beta 2-microglobulin were measured in stored plasma. RESULTS: Among the 129 patients in the immediate-treatment group, 34 had disease that progressed to AIDS, as compared with 57 of the 141 patients in the deferred-treatment group (P = 0.03). Progression to AIDS correlated strongly with base-line CD4+ lymphocyte counts (P = 0.001) and plasma levels of HIV-1 RNA (P < 0.001), but not with base-line levels of beta 2-microglobulin (P = 0.14). A decrease of at least 75 percent in the plasma level of HIV-1 RNA over the first six months of zidovudine therapy accounted for 59 percent of the benefit of treatment, defined as the absence of progression to AIDS (95 percent confidence interval, 13 to 112 percent). Plasma beta 2-microglobulin levels and CD4+ lymphocyte counts explained less of the effect of treatment. A 75 percent decrease in the plasma HIV-1 RNA level plus a 10 percent increase in the CD4+ lymphocyte count could explain 79 percent of the treatment effect (95 percent confidence interval, 27 to 145 percent). CONCLUSIONS: Treatment-induced changes in the plasma HIV-1 RNA level and the CD4+ lymphocyte count, taken together, are valid predictors of the clinical progression of HIV-related disease and can be used to assess the efficacy of zidovudine and possibly other antiretroviral drugs as well.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Fluorescent multiplex microsatellites used to define haplotypes associated with 75 CFTR mutations from the UK on 437 CF chromosomes.

The cystic fibrosis (CF) transmembrane conductance regulator (CFTR) gene contains three highly informative microsatellites: IVS8CA, IVS17bTA, and IVS17bCA. Their analysis improves prenatal/ carrier diagnosis and generates haplotypes from CF chromosomes that are strongly associated with specific mutations. Microsatellite haplotypes were defined for 75 CFTR mutations carried on 437 CF chromosomes (220 for delta F508, 217 for other mutations) from Northern Ireland and three English regions: the North-West, East Anglia, and the South. Fluorescently labelled microsatellites were amplified in a triplex PCR reaction and typed using an ABI 373A fluorescent fragment analyser. These mutations cover all the common and most of the rare CF defects found in the UK, and their corresponding haplotypes and geographic region are tabulated here. Ancient mutations, delta F508, G542X, N1303K, were associated with several related haplotypes due to slippage during replication, whereas other common mutations were associated with the one respective haplotype (e.g., G551D and R560T with 16-7-17, R117H with 16-30-13, 621 + 1G > T with 21-31-13, 3659delC with 16-35-13). This simple, fast, and automated method for fluorescent typing of these haplotypes will help to direct mutation screening for uncharacterised CF chromosomes.

Chromosomes, Human↗
PubMed1996

Pain memories in phantom limbs: a case study.

Pain experienced in a limb prior to amputation may influence the course of phantom limb pain many months later. Katz and Melzack (1990) found that 42% of their sample reported a 'somatosensory pain memory' which resembled the quality and location of a painful, or non-painful pre-amputation sensation. For many amputees, pain memories are vivid experiences which incorporate both emotional and sensory aspects of the pre-amputation pain (Katz 1992). Katz and Melzack (1990) suggest that sensory input will 'trigger' somatosensory pain memories while the affective component of a pain memory is generated by the intensity, quality and location of the current experience of phantom limb pain. The present case study used a diary design to examine whether 'triggers' could be identified for somatosensory pain memories. Over a 9-month period, the patient reported daily experience of ongoing phantom limb pain, generally confined to the distal part of the limb, and 5 episodes of injury-related phantom limb pain, primarily experienced in the calf of the missing limb. A 'trigger' was identified for each of the episodes of injury-related phantom limb pain, and a significant finding in this study was that two episodes of injury-related phantom limb pain were associated with cognitive and/or emotional, rather than sensory 'triggers'.

Abscess↗
PubMed1995

A 4-megabase YAC contig that spans the Langer-Giedion syndrome region on human chromosome 8q24.1: use in refining the location of the trichorhinophalangeal syndrome and multiple exostoses genes (TRPS1 and EXT1).

We have constructed a physical map covering over 4 Mb of human chromosome 8q24.1 and used this map to refine the locations of the genes responsible for Langer-Giedion syndrome. The map is composed of overlapping YAC clones that were identified and ordered in relation to sequence tagged sites mapped to the Langer-Giedion chromosomal region on somatic cell hybrids. The minimal region of overlap of Langer-Giedion syndrome deletions, previously identified by analysis of 15 patients, was placed on the map by analysis of 2 patients whose deletions define the endpoints. The chromosome 8 breakpoint of a balanced t(8;9)(q24.11;q33.3) translocation from a patient with trichorhinophalangeal syndrome (TRPS I) was found to be located just within the proximal end of the minimal deletion region. A deletion of 8q24.11-q24.3 in a patient with multiple exostoses was found to overlap the distal end of the LGS deletion region, indicating that the EXT1 gene is distal to the TRPS1 gene and supporting the hypothesis that Langer-Giedion syndrome is due to loss of functional copies of both the TRPS1 and the EXT1 genes.

Animals↗
PubMed1995

HIV positive patients first presenting with an AIDS defining illness: characteristics and survival.

OBJECTIVES: To study the presentation and survival of patients who present with their first diagnosis of being HIV positive at the same time as their AIDS defining illness. DESIGN: Retrospective study of patients presenting with AIDS between 1991 and 1993. SETTING: Department of genitourinary medicine, St Mary's Hospital, London. MAIN OUTCOME MEASURES: AIDS defining illness at presentation and survival after diagnosis of AIDS. RESULTS: Between January 1991 and December 1993, 97 out of 436 patients (22%) presented with their first AIDS defining illness coincident with their first positive result of an HIV test (group B). The remaining 339 patients (78%) had tested positive for HIV-1 infection within the previous eight years and had consequently been followed up in clinics before developing their first AIDS defining illness (group A). The two groups of patients did not differ in age and sex distribution, risk factors for HIV-1 infection, nationality, country of origin, or haematological variables determined at the time of the AIDS defining illness. However, the defining illnesses differed between the two groups. Illnesses associated with severe immunodeficiency (the wasting syndrome, cryptosporidiosis, and cytomegalovirus infection) were seen almost exclusively in group A whereas extrapulmonary tuberculosis and Pneumocystis carinii pneumonia were more common in group B. The survival of patients in group B after the onset of AIDS was significantly longer than that of patients in group A as determined by Kaplan-Meier log rank analysis (P = 0.0026). CONCLUSIONS: Subjects who are HIV positive and present late are a challenge to the control of the spread of HIV infection because they progress from asymptomatic HIV infection to AIDS without receiving health care. The finding that presentation with an AIDS defining illness coincident with a positive result in an HIV test did not have a detrimental effect on survival gives insights into the effects of medical intervention on disease progression after a diagnosis of AIDS.

AIDS Serodiagnosis↗
PubMed1995

Herpes simplex virus turns off the TAP to evade host immunity.

Many viruses have evolved mechanisms to avoid detection by the host immune system. Herpes simplex virus (HSV) expresses an immediate early protein, ICP47, which blocks presentation of viral peptides to MHC class I-restricted cells. The properties of the newly synthesized class I molecules in HSV-infected cells resemble those of cell lines deficient in the transporter associated with antigen processing (TAP) in that class I molecules are retained in the endoplasmic reticulum, and the heavy chain and beta 2-microglobulin subunits dissociate in detergent extracts but the complex can be stabilized by peptides. We show here that ICP47 binds to TAP and prevents peptide translocation into the endoplasmic reticulum.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1995

Failure of macrophage activation in experimental obstructive jaundice: association with bacterial translocation.

Bacterial translocation from the gastrointestinal tract and macrophage activation are central to current theories of sepsis. The relevance of both in obstructive jaundice is unclear. The effect of bile duct ligation for 7 days on bacterial translocation to mesenteric lymph nodes and on macrophage activation in a rat model was examined. Compared with an incidence of zero in sham-ligated controls, bile-duct ligated rats had a 67 per cent incidence of Gram-negative colonization of mesenteric lymph nodes. This was associated with a significant (P < 0.001) decrease in macrophage tumour necrosis factor, superoxide anion and nitric oxide production compared with that in sham controls. Spontaneous bacterial translocation occurs in experimental obstructive jaundice and is associated with marked suppression of macrophage activation. This suggests a mechanism whereby jaundiced patients may be more susceptible to persistent infection but relatively protected against uncontrolled sepsis.

Animals↗
PubMed1995

Characterization of two Epstein-Barr virus epitopes restricted by HLA-B7.

We have identified two epitopes for Epstein-Barr virus specific cytotoxic T lymphocytes (CTL) restricted by the common allele HLA-B7. They are EBNA 3C 881-9 (QPRAPIRPI) and EBNA 3A 379-387 (RPPIFIRRL). The epitopes conform well to the recently described motif for HLA-B7-binding peptides (Huckzo et al., J. Immunol. 1993. 151:2572). Titration of the peptides in CTL assays and detergent lysate binding assays revealed that extending the peptides at either the N or C terminus did not reduce their affinity for HLA-B7. This behavior contrasted with HLA-B51, which binds peptides with a similar motif to B7, and has identical amino acid residues at sites expected to form the "F" pocket of the peptide-binding groove. HLA-B51 also bound the peptide EBNA 3C 881-9, but was unable to bind peptides extended at the C terminus.

Amino Acid Sequence↗
PubMed1995

Effects of resistance training on regional and total bone mineral density in premenopausal women: a randomized prospective study.

This study was designed to assess the effects of 18 months of resistance exercise on regional and total bone mineral density (BMD) and soft tissue lean mass (STL) in premenopausal women aged 28-39 randomly assigned to an exercise or control group. Twenty-two exercise and 34 control subjects completed the 18-month training study. All subjects were previously inactive and untrained women. Initial, 5-, 12- and 18-month assessments were made of total and regional BMD and total and regional STL using dual energy X-ray absorptiometry. All subjects consumed a 500 mg/day elemental calcium supplement throughout the study. Initial Ca intake without supplement averaged 1,023 mg/day in total sample. Serum levels of bone osteocalcin and dietary assessments using 12 randomly assigned days of diet records were also completed. Muscular strength was assessed from both 1 repetition maximum (RM) testing of 10 weightlifting exercises and by peak torque for hip abduction/adduction and knee extension/flexion. Training increased strength by 58.1% based on 1 RM testing and by 33.8% based on isokinetic testing at 18 months versus baseline. BMD increased significantly above baseline at the lumbar spine for the exercise group at 5 months (2.8%), 12 months (2.3%), and 18 months (1.9%) as compared with controls. Femur trochanter BMD increased significantly (p < 0.05) in the exercise group at 12 months (1.8%) and 18 months (2.0%) but not at 5 months (0.7%) as compared with controls. No changes in total BMD, arm BMD, or leg BMD were found. There was a 20% increase in BGP in the exercise group as compared with controls at 5 months and this difference was maintained throughout the study. For STL, significant increases for total, arm, and leg were found at 5, 12, and 18 months for the exercise group versus control ranging from 1-6% over baseline. These results support the use of strength training for increasing STL and muscular strength with smaller but significant regional increases in BMD in the premenopausal population.

Absorptiometry, Photon↗
PubMed1995

AM630, a competitive cannabinoid receptor antagonist.

AM630 (iodopravadoline), a novel aminoalkylindole, has been found to attenuate the ability of a number of cannabinoids to inhibit electrically-evoked twitches of the mouse isolated vas deferens. It did not block the inhibitory effects of morphine or clonidine on the twitch response. AM630 behaved as a competitive antagonist of CP 55,940, WIN 55,212-2, anandamide and (R)-(+)-arachidonyl-1'-hydroxy-2'-propylamide (AM356), producing rightward shifts in the log concentration response curves of these cannabinoid receptor agonists that were concentration-dependent, essentially parallel and not accompanied by any decrease in the size of maximal response. AM630 also produced concentration-dependent, parallel rightward shifts in the log concentration-response curve of delta 9-THC. However, these shifts were accompanied by a decrease in the maximal response. AM630 was markedly more potent as an antagonist of delta 9-THC and CP 55,940 (Kd = 14.0 and 17.3 nM respectively) than as an antagonist of WIN 55,212-2, AM356 or anandamide (Kd = 36.5, 85.9 and 278.8 nM respectively). These differences in dissociation constant imply that the mouse vas deferens may contain more than one type of cannabinoid receptor. The data also indicate that the receptors for which AM630 has the highest affinity may not be CB1 cannabinoid receptors as the CB1 selective antagonist, SR141716A, is known to be equally potent in attenuating the inhibitory effects of CP 55,940 and anandamide on the twitch response of the mouse vas deferens.

Animals↗
PubMed1995

Antibodies to measles, mumps and rubella in UK children 4 years after vaccination with different MMR vaccines.

Persistence of antibodies 4 years after vaccination with measles, mumps and rubella (MMR) vaccine from three different manufacturers was compared in 475 children who received a single injection of vaccine when aged 12-18 months. Antibodies to measles and mumps were measured using a plaque reduction neutralisation assay; rubella antibodies were measured by radial haemolysis and latex agglutination. Children given MMR vaccine containing the Urabe mumps strain were less likely to be antibody negative than those given the Jeryl Lynn mumps strain (39/266, 15% vs 39/204, 19%, p = 0.048). However, the relatively high proportions in both groups without detectable mumps neutralising antibody suggests the probable need for a second dose in order to achieve mumps elimination. No significant differences were found in the proportions with detectable antibody to measles between vaccines containing the Schwarz and the Enders-Edmonston strains. Overall, only 3% of vaccinees were without detectable measles antibody, although a further 28% had a level below 200 mille International Units, the putative protective level for clinical measles. Geometric mean titres (GMTs) to measles were twofold higher in girls vaccinated after than before 14 months of age; GMTs in boys were intermediate and showed no age effect. Over 99% of vaccinees were seropositive to rubella, confirming the excellent immunogenicity of the RA 27/3 rubella strain and the potential for elimination of rubella with a single dose strategy.

Antibodies, Viral↗
PubMed1995

The role of coping in adjustment to phantom limb pain.

Research has indicated that the way individuals cope with pain may influence pain, and physical and psychological adjustment. The present study assessed the relationship between coping strategy use and adjustment in amputees with phantom limb pain (PLP). Coping strategies were measured using the Coping Strategies Questionnaire (CSQ) and their relationship with adjustment was examined using both composite scores and individual strategy scores. The results indicated that the relationship between coping and adjustment was primarily explained by the use of strategies within the 'Helplessness' factor of the CSQ. A clearer picture of coping strategy use was gained from examining individual strategies rather than the composite measures. Catastrophizing explained the largest proportion of variance in pain report (26%), while increasing behavioral activity and hoping or praying strategies explained a smaller proportion of the variance (3% and 1%, respectively). Catastrophizing also explained a large proportion of the variance in physical and psychosocial dysfunction (11% and 22%), while hoping or praying strategies accounted for only a small proportion of the variance in physical dysfunction (3%), and re-interpreting pain sensations accounted for a small proportion of the variance in psychosocial dysfunction (3%). The findings in this study have important clinical implications in that coping strategy use was associated with increased, rather than decreased, levels of pain and disability. However, since the reported use of coping strategies in the present study was low, further research, perhaps utilizing other measures of coping, is required to clarify these findings.

Adaptation, Psychological↗
PubMed1995

Epirubicin, cisplatin and infusional 5-fluorouracil (5-FU) (ECF) in hepatobiliary tumours.

Hepatobiliary tumours are rare, often present late and have a poor prognosis, with no current effective systemic therapy available. This study aimed to evaluate the activity and toxicity of epirubicin, cisplatin and continuous infusional 5-fluorouracil (5-FU) (ECF) in patients with these tumours. From March 1991 to November 1993, 25 patients with advanced biliary tumours and 7 with hepatoma were treated with epirubicin 50 mg/m2 and cisplatin 60 mg/m2 intravenously (i.v.) day 1, each given every 21 days and 5-FU 200 mg/m2/day given as a continuous 24 h i.v. infusion throughout the treatment course. 8 of the 20 (40%) evaluable patients with biliary tumours responded. Median duration of response was 10 months. 2 of the 7 (29%) patients with hepatoma responded. The regimen was well tolerated with minimal haematological and non-haematological toxicity. This novel regimen is active in advanced hepatobiliary tumours.

Adult↗
PubMed1995

Adjuvant chemotherapy for oesophagogastric cancer with epirubicin, cisplatin and infusional 5-fluorouracil (ECF): a Royal Marsden pilot study.

Previous trials of adjuvant chemotherapy for oesophagogastric cancer have shown only modest or no improvement in survival. However, the regimens used in these studies produce low response rates in patients with advanced disease. ECF is a new regimen which results in higher response rates and may therefore be more effective in the adjuvant setting. Twenty-nine patients who had undergone a potentially curative resection for oesphagogastric carcinoma were treated with ECF [epirubicin 50 mg m-2 and cisplatin 60 mg m-2 for 18 weeks]. The median age was 52.5 years. Three patients had oesophageal tumours, 14 had tumours of the oesophagogastric junction (OGJ) and 12 had gastric tumours. All were adenocarcinomas apart from one undifferentiated carcinoma. One patient had stage I disease, nine stage II, 17 stage II and two stage IV. The mean number of chemotherapy cycles per patient was 5.2 (range 2-8). The median follow-up was 8.4 months (1.5-36.3 months). Eleven patients relapsed during follow-up (38%). One patient had an anastomotic recurrence and ten patients distant metastases. Overall 3 year survival was 61.5% (95% confidence interval 42-79); 3 year survival in stage II was 50% (21.2-86.3) and in stage III 65.6% (40-86). Chemotherapy was well tolerated, with grade 3/4 toxicity as follows: leucopenia 13.5%, nausea and vomiting 10%, diarrhoea 3.5%, infection 3.5% and thrombocytopenia 3.5%. There were no treatment-related deaths. We conclude that ECF can be administered safely as adjuvant treatment to patients with surgically resected gastro-oesophageal carcinoma. The results, especially in patients with stage III disease, are encouraging and support the investigation of this regimen within a prospective randomised trial.

Adenocarcinoma↗