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Biomedical subjects

D M Jones

Publications and source records attributed to D M Jones.

At least 109 records · Page 6Linked to original sources
PubMed1992

Synthesized or digitized? A guide to the use of computer speech.

In addition to technical and cost determinants, a range of human factors issues governs the appropriateness of synthesized or digitized speech for a particular system. For example, since synthesized messages are created textually, they may reflect the rules and habits of written language, rather than spoken language. This may cause listeners some difficulty interpreting the intended meaning of the message. Moreover, the different speech media place constraints upon techniques of message creation editing, transmission and reception. Synthesized speech is easy to edit in terms of lexical content, but the production of sophisticated prosodic features can be problematic. In contrast, unedited digitized speech will normally have appropriate prosodic cues and because of this will be difficult to edit. The influence of these factors is examined and illustrations of both good and poor practice are given. The paper concludes with a decision criteria checklist for speech output devices.

Journal Article↗
PubMed1992

The lipooligosaccharide immunotype as a virulence determinant in Neisseria meningitidis.

We have studied the antigenic (immunotype) and physical characteristics of the lipooligosaccharide (LOS) of epidemiologically related Neisseria meningitidis case (36) and carrier (76) isolates associated with a virulent clone of meningococci (ET-5 complex). LOS immunotypes were determined by dot blotting using immunotype specific monoclonal antibodies and physical characteristics were determined from silver stained SDS-PAGE following proteinase K digestion. The genetic similarity of the different isolates was confirmed by analysis of the restriction fragment length polymorphisms. An association between LOS immunotype expression and invasive disease was found; 97% of case isolates expressed the L3,7,9 immunotype, of which 13% additionally expressed the L1,8,10 determinant. The LOS immunotypes of carrier strains were much more heterogeneous. The predominant immunotype was L1,8,10 (70%) and only 24% expressed L3,7,9 alone. Genotypically related case isolates from Norway (6) and Austria (18) expressed the L3,7,9 immunotype with similar frequency to the U.K. isolates. The combination of LOS immunotype and capsule expression appears to be related to the virulence of these meningococcal strains.

Antibodies, Bacterial↗
PubMed1992

The development of a microwave fluid-bed processor. I. Construction and qualification of a prototype laboratory unit.

The static bed- and planetary-type microwave dryers currently available to process pharmaceutical materials are not designed to use hot-air fluidization for the purpose of maximizing microwave energy inputs and particle drying. To take advantage of the benefits offered by fluidization, a 1-kg Uni-Gatt laboratory fluid bed processor was modified to support microwave-assisted fluid bed drying of several representative pharmaceutical granulations. The construction, design features, and validation of this new microwave fluid bed processor are presented.

Calibration↗
PubMed1992

H. pylori, the most common bacterial infection in Africa: a random serological study.

This study was carried out to determine the prevalence of antibodies to Helicobacter pylori in northern Nigeria, a region with a low incidence of peptic ulceration. In a random, serological survey of 268 subjects, 228 (85%) of the population studied had IgG antibodies to H. pylori. Fifty-eight of these subjects had experienced dyspepsia in the preceding 6 months. The majority of the population (82%) is infected between the ages of 5 and 10. Despite the high prevalence of antibodies to H. pylori, peptic ulcer is uncommon, suggesting that H. pylori is not important in the etiology of peptic ulcer in this population. Indeed, most patients infected by H. pylori are asymptomatic. The possible reasons for this are discussed.

Adolescent↗
PubMed1991

Influenza A and meningococcal disease.

There are several anecdotal accounts of the association between outbreaks of influenza and meningococcal disease. The exceptional increase in the number of cases of meningococcal infection 2 weeks after an influenza A outbreak in England and Wales during November and December, 1989, provided an opportunity to investigate the relation between the two events. Patients with meningococcal disease in December, 1989, were more likely than age-matched controls to show serological evidence of recent influenza A infection (odds ratio 3.9, 95% Cl 1.2-13.9). The most likely explanation for the association is immune suppression induced by influenza A, though a lowering of mucosal resistance to meningococcal invasion may also be a factor. Public health authorities should be aware of the association and should be prepared to alert medical practitioners and the public to the increased risk of meningococcal disease when influenza A outbreaks occur.

Adult↗
PubMed1991

Point mutation in meningococcal por A gene associated with increased endemic disease.

The por A gene, which encodes expression of meningococcal class 1 outer membrane protein, responsible for antigenic subtype specificity, has been cloned and sequenced in an isolate of Neisseria meningitidis (B:15:P1.7,16) from a patient in the Gloucester area with meningococcal meningitis. Comparison of the sequence with that of the equivalent gene from the P1.7,16 reference strain reveals a point mutation which generates a single aminoacid change in the epitope responsible for P1.16 specificity. Monoclonal antibodies with P1.16 specificity do not react with synthetic peptides that correspond to the altered epitope, and do not promote complement-mediated bactericidal killing of the isolate. Analysis of other strains shows widespread distribution of infections due to B:15:P1.7,16 meningococci with the altered epitope (P1.16b) in England and Wales.

Antibodies, Monoclonal↗
PubMed1991

Successful engraftment of human postnatal thymus in severe combined immune deficient (SCID) mice: differential engraftment of thymic components with irradiation versus anti-asialo GM-1 immunosuppressive regimens.

To develop a model of human thymus growth in vivo, we have implanted postnatal human thymus under the renal capsule of severe combined immune deficient (SCID) mice and assayed for graft survival and graft characteristics 1-3 mo after engraftment. Three groups of SCID mice were engrafted with postnatal human thymus: untreated SCID mice, SCID mice pretreated with 400 cGy of gamma irradiation 1-5 d before engraftment, and SCID mice treated with intraperitoneal anti-asialo GM-1 antiserum every 4-5 d during engraftment. In the untreated group of SCID mice, only 37% of grafts survived and consisted of human thymic microenvironment components and human immature thymocytes. Irradiation of SCID mice before engraftment improved survival of human thymic grafts to 83%, but these grafts were largely devoid of thymocytes and contained only thymic microenvironment components with large numbers of thymic macrophages. Treatment of SCID mice with anti-asialo GM-1 antiserum throughout the engraftment period also promoted human thymus engraftment (70%) and induced SCID B cell Ig production (SCID[Ig+]) in 38% of animals. In SCID(Ig-) anti-asialo GM-1-treated mice, the human thymic grafts were similar in content to those in untreated SCID mice. However, in anti-asialo GM-1-treated animals with grafts that became SCID(Ig+), all animals were found to have mouse-human chimeric grafts in that the human thymic microenvironment (human fibroblasts, thymic epithelium, vessels) was colonized by murine T cells. These data demonstrate that human postnatal thymus will grow as xenografts in SCID mice, and that the components of human thymus that engraft are dependent on the immunosuppressive regimen used in recipient mice. A striking finding in this study was the induction of T and B lymphopoiesis in SCID mice by abrogation of NK cell activity with in vivo anti-asialo GM-1 treatment. These data strongly suggest that asialo GM-1+ NK cells and/or macrophages play a role in mediation of suppression of lymphopoiesis in SCID mice.

Animals↗
PubMed1991

Updating one's knowledge about the current status of vehicles in a freight system simulation.

The use of simulations of real-world settings can provide data relevant to ergonomics problems in a wide range of similar settings. This paper reports on a simulation of a freight service operation. It examines the effect of manipulating the type and format of information representation on the ability to update knowledge about the status of three vehicles. In addition, the effects of display type and the detection of violations of pre-learned rules on the ability to update are examined. The display format proved not to be a critical factor but the requirement to detect rule violations of a specific vehicle resulted in better memory-updating performance for that vehicle. The results are discussed in terms of a human memory mechanism, which is analogous to a computer operating system, involved in updating memory and detecting violations. Finally, the value of using this tool to examine complex cognitive processes relevant to the workplace is discussed.

Journal Article↗
PubMed1991

Chemoprophylaxis of meningitis.

Chemoprophylaxis of meningitis caused by Neisseria meningitidis and Haemophilus influenzae may be determined by the epidemiology of transmission, the antibiotic susceptibility patterns of the organisms, and the usage of vaccines. A review of transmission in England distinguishes differences in sporadic and cluster meningococcal infections. Because of resistance to sulphadiazine, rifampicin and ciprofloxacin are prophylactic agents of choice. Vaccination can be a useful adjunct to antibiotic prophylaxis. Prophylaxis for meningitis due to H. influenzae type b can be provided by rifampicin and vaccination can also be an adjunct to antibiotic prophylaxis.

Ciprofloxacin↗
PubMed1991

The surface structure seen on gonococci after treatment with CMP-NANA is due to sialylation of surface lipopolysaccharide previously described as a 'capsule'.

Phenotypic serum resistance of gonococci in urethral exudates is due to sialylation of lipopolysaccharide (LPS) by host cytidine 5'-monophospho-N-acetyl neuraminic acid (CMP-NANA). A surface structure was visible on gonococci [strain BS4 (agar)] that had been stained with ruthenium red after incubation with CMP-NANA. This structure was not visible after neuraminidase treatment, which released sialic acid but not LPS. The LPS profiles of strain BS4 (agar) had another in vivo-selected strain Gc40 (variant D1), were similar. A monoclonal antibody (mAb) which recognises epitope C on the LPS of 'capsulated' gonococci was shown by immunoblotting to react with several LPS components, including one of about 4.5 kDa which contains the probable site of sialylation by CMP-NANA. The reactions with the mAb were not affected by growing the strains with CMP-NANA nor by neuraminidase treatment of the sialylated LPS. The mAb also gold-labelled the surface of both strains before and after treatment with CMP-NANA. These data indicate that sialylation by CMP-NANA and staining with ruthenium red renders more visible the surface LPS which, sometimes in the past, has been seen as a 'capsule'.

Antibodies, Monoclonal↗
PubMed1991

A study of risk factors for Campylobacter infection in late spring.

A case-control study was carried out to investigate possible reasons for the large increase in the number of cases of infection caused by Campylobacter species reported in the Regional Epidemiology Section of Manchester Public Health Laboratory in late spring each year. The hypothesis tested was that a risk factor peculiar to campylobacter infection is responsible for this phenomenon. Interviews about a wide variety of risk factors were conducted with 29 patients suffering from campylobacter enteritis and 41 out of a control group of 42 with acute diarrhoeal illness from other causes. The only statistically significant association with campylobacter infection was having had milk bottle tops pecked by birds, while previously recognised associated factors such as outdoor activities, pet ownership and consumption of chicken showed no significant association. Interviewees identified the birds responsible as magpies.

Acute Disease↗
PubMed1991

Analysis of clones derived from human CD7+CD4-CD8-CD3- thymocytes.

The differentiation of human thymocyte precursors was studied by analysis of clonal progeny of CD4-CD8-CD3- (triple negative or TN) thymocytes. Using a culture system of phytohemagglutinin, IL-2, and irradiated allogeneic lymphoid feeder cells, we found that 48% of clones (104 total) derived from TN thymocyte suspensions were TCR gamma delta cells, 12% of clones were TCR alpha beta cells, and 34% were CD16+CD3- cells. Importantly, 6% of clones were novel subsets of CD4+CD8-CD3- or CD4-CD8+CD3- thymocytes. The majority of TCR alpha beta, TCR gamma delta, and CD16+CD3- clones expressed low levels of CD4. Molecular analysis of freshly isolated TN- thymocytes prior to in vitro culture demonstrated that up to 40% of cells had TCR gamma, delta, and beta gene rearrangements, but were negative in indirect immunofluorescence assays for cytoplasmic TCR delta and beta. These data provide evidence at the clonal level for the presence of precursors of the TCR alpha beta and TCR gamma delta lineages in the human TN thymocyte pool. Moreover, a substantial proportion of freshly isolated human TN thymocytes had already undergone TCR gene rearrangement prior to in vitro culture. Whether these precursors of the TCR alpha beta and TCR gamma delta lineages mature from cells already containing TCR gene rearrangements into sTCR+ cells or differentiate in vitro from cells with TCR genes in germline configuration remains to be determined. Nonetheless, these data demonstrate that the predominant clone types that grow out of human TN thymocytes in vitro are TCR gamma delta and NK cells.

Antigens, CD↗
PubMed1991

Serological evidence of infection with Helicobacter pylori may predict gastrointestinal intolerance to non-steroidal anti-inflammatory drug (NSAID) treatment in rheumatoid arthritis.

Specific circulating antibodies to the spiral gastric organism, Helicobacter pylori (HP) were detectable in 43% of 68 patients with rheumatoid arthritis by complement fixation test (CFT) and enzyme-linked immunosorbent assay (ELISA), a frequency comparable with that of a normal, age-matched population. Presence of these antibodies correlated strongly with a previous history of peptic ulcer disease (PUD) and to the severity of NSAID-related dyspeptic symptoms, the latter often leading to multiple drug intolerance. This contrasts with short term, prospective NSAID toxicity data, which show little relationship between ulceration and HP carriage. This result suggests, however, that HP may have a definite role in the pathogenesis of symptomatic PUD associated with more chronic NSAID usage, and may have important implications for ulcer prophylaxis in these patients.

Adult↗