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Biomedical subjects

M Hughes

Publications and source records attributed to M Hughes.

At least 73 records · Page 4Linked to original sources
PubMed1999

Generation of influenza A viruses entirely from cloned cDNAs.

We describe a new reverse-genetics system that allows one to efficiently generate influenza A viruses entirely from cloned cDNAs. Human embryonic kidney cells (293T) were transfected with eight plasmids, each encoding a viral RNA of the A/WSN/33 (H1N1) or A/PR/8/34 (H1N1) virus, flanked by the human RNA polymerase I promoter and the mouse RNA polymerase I terminator-together with plasmids encoding viral nucleoprotein and the PB2, PB1, and PA viral polymerases. This strategy yielded >1 x 10(3) plaque-forming units (pfu) of virus per ml of supernatant at 48 hr posttransfection. The addition of plasmids expressing all of the remaining viral structural proteins led to a substantial increase in virus production, 3 x 10(4)-5 x 10(7) pfu/ml. We also used reverse genetics to generate a reassortant virus containing the PB1 gene of the A/PR/8/34 virus, with all other genes representing A/WSN/33. Additional viruses produced by this method had mutations in the PA gene or possessed a foreign epitope in the head of the neuraminidase protein. This efficient system, which does not require helper virus infection, should be useful in viral mutagenesis studies and in the production of vaccines and gene therapy vectors.

Animals↗
PubMed1999

Efficacy and safety of delavirdine mesylate with zidovudine and didanosine compared with two-drug combinations of these agents in persons with HIV disease with CD4 counts of 100 to 500 cells/mm3 (ACTG 261). ACTG 261 Team.

To evaluate the antiretroviral activity of delavirdine mesylate, a non-nucleoside reverse transcriptase inhibitor of HIV-1, we performed a phase II, randomized, double-blind, multicenter trial comparing the three-drug combination of delavirdine with zidovudine and didanosine to two-drug combinations of these drugs. Patients with CD4 cell counts between 100 and 500 cells/mm3 without prior or <6 months of monotherapy with zidovudine or didanosine were randomized to one of four arms and observed on a follow-up basis for 48 weeks. In total, 544 patients were evaluated. In those assigned to the three-drug regimen, mean short-term (weeks 4-12) and long-term (weeks 40-48) change in CD4 cells from baseline were 49.3+/-8.1 and 65.4+/-13.4 cells/mm3, respectively; mean short-term and long-term HIV-1 RNA changes from baseline were -1.13 log10+/-0.12 and -0.73+/-0.12 copies/ml, respectively. These responses in CD4 cell counts and HIV-1 RNA levels were better in comparisons with each of the two-drug arms at all study points; however, differences were not consistently significant. Gastrointestinal side effects were experienced by 33% of patients (178 of 544), and 30% (121 of 407) receiving delavirdine experienced rash, only one case of which was severe. In this study, therapy with delavirdine + zidovudine + didanosine was safe and showed modest, but not always significant, antiviral activity and CD4 cell count benefit compared with two-drug regimens with these agents. Key

Adult↗
PubMed1999

Successful preimplantation genetic diagnosis for sex Link Lesch--Nyhan Syndrome using specific diagnosis.

Lesch-Nyhan syndrome (LN) is a severe X-linked recessive disorder caused by a deficiency of the enzyme hypoxanthine phosphoribosyl transferase (HRT). Clinical features displayed by affected boys are particularly severe and disturbing and include hyperuricaemia, Characteristic neurological features including self-mutilation, choreothetosis, spasticity and mental retardation. A couple with a boy diagnosed with LN and a history of pregnancy termination was referred to the Hammersmith Hospital. Their affected son was born in 1982 after an uncomplicated pregnancy and vaginal delivery. Eight subsequent pregnancies had been unsuccessful. There were five therapeutic terminations and three spontaneous abortions, one at least directly caused by the sampling procedure during amniocentesis. From 1989 to 1991 two unsuccessful preimplantation genetic diagnosis (PGD) cycles by sexing were performed by DNA amplification. The mutation was characterized and a nested PCR protocol was designed which allowed the efficient amplification of the affected loci followed by the detection of the mutant allele by restriction digestion. Three PGD cycles were performed using this specific diagnostic test before a successful pregnancy was achieved resulting in the birth of a healthy unaffected baby girl.

Embryo Transfer↗
PubMed1999

Measurement of endogenous and exogenous alpha-granular platelet proteins in patients with immune and nonimmune thrombocytopenia.

Idiopathic thrombocytopenic purpura (ITP) is caused by antiplatelet antibodies and is characterized by increased platelet destruction and elevated levels of IgG (platelet-associated IgG, PAIgG). Nonimmune thrombocytopenic patients also have elevated levels of PAIgG. In this study we investigated two possible biological explanations for the increased levels of PAIgG in these patients. The first hypothesis suggests that a thrombocytopenic stress causes increased thrombocytopoiesis with increased numbers and content of the platelet alpha granules. The second hypothesis is that for uncertain reasons (immunological or cytokine) there is increased absorption of plasma proteins by either megakaryocytes or by the platelets themselves. To address this issue, we compared the level of megakaryocyte synthesized alpha granular proteins [platelet factor 4 (PF4) and beta-thromboglobulin (beta-TG)] to plasma-absorbed alpha granular proteins (albumin, IgG and fibrinogen) in patients with immune (n = 39) and nonimmune (n = 60) thrombocytopenias. Plasma-absorbed alpha-granular proteins were elevated in both immune and nonimmune thrombocytopenia with no increase in megakaryocyte synthesized alpha-granular proteins. These plasma-derived protein elevations were not attributable to elevated mean platelet volumes or elevated plasma concentrations of the respective protein. We hypothesize that the increased IgG in these platelets is not the result of production of larger platelets, but reflects a selective increase in the endocytosis of plasma-absorbed alpha-granular proteins at the megakaryocyte and/or platelet level.

Albumins↗
PubMed1999

Characteristics of maternal directiveness and responsiveness with young children with visual impairments.

The purpose of this study was to investigate the relation between maternal responsive and directive behaviours and the development of young children with visual impairments. The participants were 17 mother-child dyads, and the children's ages ranged from 20 to 36 months of age. The amount, quality, and appropriateness of four maternal behaviours were rated during a free play session between mother and child and compared with a developmental outcome measure designed for young children with visual impairments. In general, the results showed that the quality of maternal control and appropriateness of directiveness were positively related to children's language development; whereas, the amount of these same behaviours was negatively related to language development. The findings also indicated that both the quality and amount of maternal goal-setting behaviours, and the quality of responsiveness were positively related to children's language skills, exploration of the environment and sensorimotor development. The findings are discussed in terms of maternal influence on child development.

Child Language↗
PubMed1999

Nursing workload: an unquantifiable entity.

BACKGROUND: In the increasingly prominent drives towards cost containment and efficiency nursing is under pressure to justify its value to healthcare. On the surface nursing workload assessment methods would appear to offer a means to quantify the nursing input to patient care. AIMS: To examine the validity of nursing workload methods with respect to nursing practice and nursing knowledge. FINDINGS: Previous studies and the conclusions of subject reviews have cast doubt on the reliability and validity of most methods and indicate that they have no clear theoretical base. CONCLUSION: It appears that nursing is more concerned with knowledge processing and nurses' intentions than just with the activities of caring. It is suggested that patients control the time element of nursing care. The need for nursing workload information, despite its validity problems, is discussed and a pragmatic solution is suggested.

Diagnosis-Related Groups↗
PubMed1999

Endurance training reduces the rate of diaphragm fatigue in vitro.

PURPOSE: The present study examined the effects of endurance training on the contractile and biochemical properties of the rat costal diaphragm in vitro. METHODS: Sixty-four rats were divided into two groups: exercise trained (T) and control (C). Training consisted of treadmill running 5 d x wk(-1), 60 min x d(-1) at approximately 70% of VO2max, over a 10-wk period. RESULTS: Control diaphragm strips produced an average of 12% less force from minute 15 to 50 of a 60-min in vitro fatigue protocol, compared with the T diaphragm strips (P < 0.01). T diaphragms had 10.1% higher citrate synthase (CS) and 12.1% higher superoxide dismutase (SOD) activities compared with the C (P < 0.05). Despite a significant decrease (P < 0.05) in Type IIb myosin heavy chains (MHC) and an increase (P < 0.05) in Type I MHC in T diaphragms, maximal shortening velocity (Vmax) in the diaphragm was not different between T and C animals. No differences were observed in specific force or the relative proportions of myosin light chains between groups. CONCLUSIONS: These findings suggest that endurance training reduces the rate of diaphragm fatigue in vitro but has no effect on Vmax or specific force.

Animals↗
PubMed1999

Exercise-induced alterations in skeletal muscle myosin heavy chain phenotype: dose-response relationship.

This study investigated the effects of exercise training duration on the myosin heavy chain (MHC) isoform distribution in rat locomotor muscles. Female Sprague-Dawley rats (120 days old) were assigned to either a sedentary control group or to one of three endurance exercise training groups. Trained animals ran on a treadmill at approximately 75% maximal O2 uptake for 10 wk (4-5 days/wk) at one of three different exercise durations (30, 60, or 90 min/day). Training resulted in increases (P < 0.05) in citrate synthase activity in the soleus and extensor digitorum longus in both the 60 and 90 min/day duration groups and in the plantaris (Pla) in all three exercise groups. All durations of training resulted in a reduction (P < 0.05) in the percentage of MHCIIb and an increase (P < 0.05) in the percentage of MHCIIa in the Pla. The magnitude of change in the percentage of MHCIIb in the Pla increased as a function of the training duration. In the extensor digitorum longus, 90 min of daily exercise promoted a decrease (P < 0.05) in percentage of MHCIIb and increases (P < 0.05) in the percentages of MHCI, MHCIIa, and MHCIId/x. Finally, training durations >/=60 min resulted in an increase (P < 0.05) in the percentage of MHCI and a concomitant decrease (P < 0.05) in the percentage of MHCIIa in the soleus. These results demonstrate that increasing the training duration elevates the magnitude of the fast-to-slow shift in MHC phenotype in rat hindlimb muscles.

Animals↗
PubMed1999

Suxamethonium and critical illness polyneuropathy.

Administration of suxamethonium to patients with critical illness polyneuropathy may produce life-threatening hyperkalaemia. A questionnaire to assess the awareness of this problem was sent to all UK intensive care units. A clinical scenario suggestive of critical illness polyneuropathy was accompanied by a list of possible drugs used to facilitate endotracheal intubation. Most respondents (68.7%) chose suxamethonium while 20.4% avoided any muscle relaxant. This result suggests a worrying lack of appreciation of the dangers of suxamethonium use in critical illness polyneuropathy.

Adult↗
PubMed1999

Ran-GTP stabilises microtubule asters and inhibits nuclear assembly in Xenopus egg extracts.

Ran is an abundant GTPase of the Ras superfamily that is highly conserved in eukaryotes. In interphase cells, Ran is mainly nuclear and thought to be predominantly GTP-bound, but it is also present in the cytoplasm, probably GDP-bound. This asymmetric distribution plays an important role in directing nucleocytoplasmic transport. Ran has also been implicated in cell cycle control, including the transition from mitosis to interphase when the compartmentalisation of the nucleus is established. Here, we have examined the role of Ran in this transition using a cell-free system of Xenopus egg extracts supplemented with sperm heads that provides a model for microtubule aster formation and post-M phase nuclear assembly. Ran-GTP, added as wild-type protein, a mutant defective in GTPase activity (Q69L), or generated by addition of the specific nucleotide exchange factor RCC1, stabilises large microtubule asters nucleated at the sperm centrosome, prevents the redistribution of NuMA from the aster to the nucleus and blocks chromatin decondensation. In contrast, Ran GDP does not stabilise microtubules or inhibit nuclear assembly. RanT24N and RanBP1, which oppose the generation of Ran-GTP by RCC1, arrest nuclear growth after disappearance of the aster. Ran associates with microtubule asters in egg extracts and with mitotic spindles in somatic Xenopus cells, suggesting that it may affect microtubule stability directly. These results show that Ran has a novel function in the control of microtubule stability that is clearly distinct from nucleocytoplasmic transport. The Ran GDP/GTP switch may play a role in co-ordinating changes in the structure of microtubules and the assembly of the nucleus associated with the transition from mitosis to interphase.

Animals↗
PubMed1998

HIV-1 reverse transcriptase codon 215 mutation in plasma RNA: immunologic and virologic responses to zidovudine. The AIDS Clinical Trials Group Study 175 Virology Team.

Treatment of HIV infection with zidovudine (ZDV) may select for changes in the genetic sequence of the viral reverse transcriptase (RT) that imparts drug resistance. The presence of a 2-bp mutation at codon 215 of RT (from threonine to phenylalanine or tyrosine) was assessed in plasma viral RNA in 85 subjects treated with ZDV in the AIDS Clinical Trials Group (ACTG) 175 virology substudy. Median CD4 cell numbers, HIV plasma RNA levels, and infectious titers of virus were significantly different over 56 weeks of treatment among 58 subjects with the wild-type threonine at codon 215 virus at study entry compared with the 27 subjects with mutations to phenylalanine or tyrosine (MUT) virus. Thirty percent (13 of 44 subjects) with wild-type virus at study entry developed a new codon 215 mutation. Genotypic resistance at codon 215 in plasma HIV RNA is associated with the subsequent immunologic and virologic failure of ZDV monotherapy in subjects with 200 to 500 CD4 cells/mm3.

Anti-HIV Agents↗
PubMed1998

Survey of the Free and Conjugated Myricetin and Quercetin Content of Red Wines of Different Geographical Origins.

Gradient reversed-phase HPLC was used to obtain quantitative estimates of the levels of free and conjugated myricetin and quercetin in 65 red wines from Italy, Chile, France, California, Australia, Bulgaria, Spain, Romania, New Zealand, Brazil, Morocco, and Hungary. The concentrations of total flavonols ranged from 4.6 to 41.6 mg L(-1). High total flavonol levels appear to be associated with the use of thick-skinned grape varieties, such as Cabernet Sauvignon, with a high skin:volume ratio, which were left to ripen fully in sunny conditions before harvest and which were extracted efficiently by modern methods of vinification. Some Chilean Cabernet Sauvignon wines contained up to 40 mg of total flavonols L(-1), which was higher than the levels detected in Cabernet Sauvignon from France, California, and Australia. The flavonol content of 1989 and 1990 Cabernet Sauvignon from Bulgaria was <6 mg L(-1). Chilean Cabernet Sauvignon, Merlot, and Pinot Noir all contained consistently higher concentrations of flavonols than their counterparts from different geographical regions.

Journal Article↗
PubMed1998

The processing of yeast pheromones.

Yeast provides an attractive system in which to study proprotein processing. Many of their processing events are remarkably similar to those in higher eukaryotes and their amenability to experimental manipulation permits approaches that are not always feasible in multicellular organisms. Analysing the biosynthesis of the yeast mating pheromones has been particularly rewarding and has provided insights into both the proteolytic aspects of processing and other post-translational events such as prenylation and carboxymethylation.

Amino Acid Sequence↗
PubMed1998

Extracellular degradation of agonists as an adaptive mechanism.

Many cellular responses are initiated by the binding of an extracellular ligand to receptors at the cell surface. The removal of these ligands, or agonists, would therefore be expected to contribute to the process by which cells recover from stimulation. While dilution in the extracellular medium reduces the concentration of most agonists, many cells have developed specific mechanisms for removing particular ligands. One of the more effective mechanisms is to degrade the extracellular agonist and here we review the production and action of the enzymes responsible for the degradation of a number of these agonists.

Acetylcholinesterase↗
PubMed1998

Differences between African American and Caucasian men participating in a community-based prostate cancer screening program.

Prostate cancer is a major contributor to morbidity and mortality in the male population, but public awareness of the cancer has been reported as minimal. We evaluated the effectiveness of an educational prostate cancer screening program on 944 men in a midwest urban community. Digital rectal examinations and PSA blood tests were provided at no charge to participants with a grant from the Michigan Department of Community Health. An educational intervention that stressed the importance of prostate cancer early detection and treatment was conducted before screenings. A brief questionnaire administered before and after the videotape and screenings, targeted both knowledge and attitudes concerning prostate cancer. Pre-test results revealed that African American men were significantly (t = 3.7, P = .00) less likely then white men to correctly identify early symptoms of prostate cancer and the basic components of a prostate checkup. Following program involvement, scores significantly improved in all areas and differences were no longer significant between the races. Racial differences were also found for screening preferences and modes of reaching men to participate in screening. African American men were twice as likely as white men to choose private appointments over mass screening (OR = 2.2, P = .00). Radio reached the most African Americans (25%) while newspaper reached the most Caucasians (34%). The decreased level of knowledge among African Americans regarding prostate etiology and clinical factors highlights the need for educational programs to target minority populations. The need for discretion also applies by providing minority-favored access with screening through private appointments.

Adult↗