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Biomedical subjects

M H Jackson

Publications and source records attributed to M H Jackson.

At least 19 recordsLinked to original sources
PubMed2001

Sources of the eutrophication problems associated with toxic algae: an overview.

Blooms of cyanobacteria (toxic blue-green algae) can produce health and environmental hazards in water, including water used for drinking or recreational purposes. How, why, and when these blooms are produced, as well as how to deal with them, are questions whose answers are vital to the safeguarding of public health in regions where the algae occur. The blooms are linked to eutrophication of water, and this paper discusses the eutrophication problems, their nature, and their relevance to the production of cyanobacteria. Nutrient limitations on algal productivity are considered, as is the involvement of the atmosphere, the storage of nutrients in soils, and the influence of anthropogenic activity.

Agriculture↗
PubMed2000

The putative proteinase maturation protein A of Streptococcus pneumoniae is a conserved surface protein with potential to elicit protective immune responses.

Surface-exposed proteins often play an important role in the interaction between pathogenic bacteria and their host. We isolated a pool of hydrophobic, surface-associated proteins of Streptococcus pneumoniae. The opsonophagocytic activity of hyperimmune serum raised against this protein fraction was high and species specific. Moreover, the opsonophagocytic activity was independent of the capsular type and chromosomal genotype of the pneumococcus. Since the opsonophagocytic activity is presumed to correlate with in vivo protection, these data indicate that the protein fraction has the potential to elicit species-specific immune protection with cross-protection against various pneumococcal strains. Individual proteins in the extract were purified by two-dimensional gel electrophoresis. Antibodies raised against three distinct proteins contributed to the opsonophagocytic activity of the serum. The proteins were identified by mass spectrometry and N-terminal amino acid sequencing. Two proteins were the previously characterized pneumococcal surface protein A and oligopeptide-binding lipoprotein AmiA. The third protein was the recently identified putative proteinase maturation protein A (PpmA), which showed homology to members of the family of peptidyl-prolyl cis/trans isomerases. Immunoelectron microscopy demonstrated that PpmA was associated with the pneumococcal surface. In addition, PpmA was shown to elicit species-specific opsonophagocytic antibodies that were cross-reactive with various pneumococcal strains. This antibody cross-reactivity was in line with the limited sequence variation of ppmA. The importance of PpmA in pneumococcal pathogenesis was demonstrated in a mouse pneumonia model. Pneumococcal ppmA-deficient mutants showed reduced virulence. The properties of PpmA reported here indicate its potential for inclusion in multicomponent protein vaccines.

Amino Acid Sequence↗
PubMed2000

Problems associated with the use of pit latrines in Blantyre, Republic of Malawi.

A questionnaire and observational study was conducted to determine the problems associated with construction, design and hygiene methods used to maintain pit latrines in a high-density urban township in Malawi. The survey comprised 100 randomly selected households and the person responsible for the latrine maintenance was interviewed. Eighty-seven percent of householders used traditional latrines, 67% with earthen and 20% with concrete (i.e. sanitation platform, also known as San-plats) floors. A variety of makeshift squat-hole covers (e.g. iron sheets, rocks, cardboard) are used by those who cannot afford San-plats to reduce fly and odour problems. Most squat-hole covers were fouled with faecal matter and some presented risk of invasive injury due to sharp edges. Five households used ventilated improved latrines whilst the remaining eight per cent made use of their neighbour's latrine. Ownership of property, poverty and theft in the area significantly influenced the type and structural condition of the latrine. Walls, ceilings and doors of the superstructure comprised a mixture of miscellaneous materials (i.e. cardboard, paper, cloth, brick) making the hygienic upkeep of the latrine difficult. Cloth doors were often used for hand drying. Geographical location, such as rocky terrain with inadequate soil consolidation, and environmental conditions, such as heavy rains and floods, exacerbate structural defects. Coupled with the lack of attention afforded to the disposal of young children's faeces, wash-water and pit surcharging, the potential exists for widespread contamination of the surrounding environment and transmission of faecal-oral disease. More than half of the respondents stressed that they had not received any information regarding health education and hygienic maintenance of the latrine. As such, there is need for a hygiene education programme to promote awareness of appropriate sanitation and behavioural change. Cultural and religious factors were found not to influence latrine use.

Female↗
PubMed1998

Intravenous corticotrophin vs. hydrocortisone in the treatment of hospitalized patients with Crohn's disease: a randomized double-blind study and follow-up.

Adrenocorticotrophic hormone (ACTH) and corticosteroids have no maintenance values for inflammatory bowel disease but serve to reduce the severity of disease. The effectiveness of intravenous corticotrophin versus hydrocortisone in ulcerative colitis has been determined including whether previous steroid therapy influenced the better response to one rather than the other, but no such studies have ever been done in Crohn's disease. Eighty-eight patients hospitalized with moderate-to-severe Crohn's disease (Present-Korelitz [P-K] Index -3 to -2 and the International Organisation for the Study of Inflammatory Bowel Disease-Crohn's & Colitis Foundation of America [IOIBD-CCFA] Index, mean 14, range 5-23) were treated in a prospective, randomized, double-blind clinical trial to receive either continuous intravenous infusion of 120 U/day of ACTH (44 patients) or hydrocortisone 300 mg/day (44 patients). Patients were also subdivided into those who received oral steroids during the 30 days prior to intravenous therapy and those who had not. Response was followed on a daily basis and tabulated at 3, 5, and 10 days. Patients were followed from 1-3 years to determine the later status. After 10 days of intravenous therapy 36 of 44 patients (82%) who received ACTH and 41 of 44 patients (93%) who received hydrocortisone fully responded (P-K index +3 and IOIBD-CCFA Index mean of 3). At the end of the study, response to intravenous ACTH and hydrocortisone was not statistically different whether or not patients received oral steroids during the 30 days prior to admission, although the response to IV ACTH tended to be faster at 3 days in those who had received previous steroid therapy. Intravenous ACTH and hydrocortisone are equally effective in achieving therapeutic goals in patients with Crohn's disease who have not achieved results with oral medications. Moreover the response rate was high (mean 88%), serving to buy time for establishment of successful maintenance programs of treatment with oral 5-ASA and immunosuppressive drugs for 69% of patients at 1-3 years.

Administration, Oral↗
PubMed1995

Self-concept correlates between at-risk and not-at-risk ninth-grade students.

This study examined whether the Tennessee Self-concept Scales could be used to discriminate among 43 ninth-grade students who were designated as being at risk of dropping out of high school and 47 students who were thought to show probability of persisting. Scores on the scales were submitted to stepwise multivariate discriminant analysis. Scores on the Self-satisfaction Scale constituted a linear function that correctly classified 72.22% of the subjects. Further investigation confirmed a 13-item scale selected from the Tennessee Self-concept Scales correctly identified the classification of 76.67% of the students.

Adolescent↗
PubMed1995

Bittering agents: their potential application in reducing ingestions of engine coolants and windshield wash.

Ethylene glycol automobile engine coolants and methanol-based windshield washer liquids are toxic. Despite international attempts to improve the safety of these products through better labelling and packaging, accidental and intentional ingestions continue a source of poisonings worldwide. The rejection of bitter tasting substances forms part of the human defense against ingestion of harmful substances. Denatonium benzoate (DB) is currently recognised as a means to prevent ingestion of ethyl alcohol intended for industrial use. This study investigated the use of this bitter substance also as a deterrent against ingesting ethylene glycol and methanol. The palatability of ethylene glycol and methanol with and without the addition of DB was assessed using a human taste panel; 30 ppm DB rendered each product intolerable to the panel. The addition of DB to ethylene glycol engine coolants and methanol-based windshield washer liquids at low concentrations could afford protection against accidental ingestions.

Adolescent↗
PubMed1993

Occurrence of Giardia sp. cysts and Cryptosporidium sp. oocysts in faeces from public parks in the west of Scotland.

One hundred faecal specimens, randomly collected from various locations within seven public parks in the west of Scotland, were examined for the presence of Giardia sp. cysts and Cryptosporidium sp. oocysts. Eleven percent of samples contained Giardia sp. cysts and 1% contained Cryptosporidium sp. oocysts. Occurrence data from individual parks varied from 0 to 40% for Giardia and 0 to 2.4% for Cryptosporidium. The occurrence of parasitic organisms in public parks, especially in the vicinity of children's playing areas is a matter of concern for public health officials and regulators of leisure and recreation amenities.

Animals↗
PubMed1992

Neutrophil count and activation in vascular disease.

An elevated peripheral leucocyte count is associated with an increased risk of myocardial infarction and progression of coronary artery disease. The aim of this study was to determine neutrophil count and activation, measured as an increase in plasma neutrophil elastase, in patients with stable ischaemic heart disease, insulin-dependent diabetes mellitus and essential hypertension compared with a comparable group of control subjects. Neutrophil count and neutrophil elastase were raised significantly for patients with ischaemic heart disease (p less than 0.005; p less than 0.002), diabetes mellitus (p less than 0.001; p less than 0.01) and hypertension (p less than 0.05; p less than 0.0001) respectively compared to the control subjects. Neutrophil elastase did not correlate with subject age or leucocyte count. This study confirms the association between leucocyte count and vascular disease, and is consistent with neutrophil activation contributing to the progression of vascular disease.

Adult↗
PubMed1990

Workplace protection factors of HSE approved negative pressure full-facepiece dust respirators during asbestos stripping: preliminary findings.

This research was designed to evaluate the workplace protection factors of Health and Safety Executive Approved, negative pressure full-facepiece dust respirators, during asbestos stripping. A standard method to measure the concentration of asbestos fibres inside full-facepiece respirators has been developed and the workplace protection factors have been calculated from the data obtained. The respirators in this study are approved for use by the Health and Safety Executive in concentrations of up 900 times the Control Limit [HEALTH AND SAFETY EXECUTIVE, Guidance Note EH 41 (1985)] but the preliminary test results suggest that this level is inappropriately high for this type of respiratory protective equipment.

Asbestos↗
PubMed1989

Neutrophil activation during cell separation procedures.

Leucocytes labelled with 111In or 99Tcm are used as diagnostic agents for detecting sites of infection by scintigraphy. Before radiolabelling is performed, leucocytes are isolated from whole blood. The effect of isolation procedures on neutrophil activation has been studied by measuring the neutrophil elastase produced during incubation of whole blood with three erythrocyte sedimentation agents (dextran 70, hydroxyethyl starch and methylcellulose) and two density gradient media (Percoll and Mono-Poly Resolving Medium). Neutrophil elastase was measured using a standard radioimmunoassay. At 21 degrees C, dextran caused no elastase release while hydroxyethyl starch and methylcellulose induced significant release (p = 0.01 and p less than 0.01 resp.). All three agents caused significant elastase release at 37 degrees C. When whole blood was incubated with Percoll and Mono-Poly Resolving Medium, no release of neutrophil elastase was observed. These results show that neither density gradient medium induces neutrophil activation but that certain erythrocyte sedimentation agents do. Of the three sedimentation agents investigated, dextran is the agent of choice if neutrophil activation is to be minimized.

Cell Separation↗
PubMed1987

A seroepidemiological survey of toxoplasmosis in Scotland and England.

The Sabin-Feldman dye test was used to detect the presence of Toxoplasma antibodies in two groups of blood donors in central Scotland, one group from a rural area and one from an urban area, and in patients attending a medical outpatients clinic and females attending an antenatal clinic serving a mixed urban and rural area in the midlands of England. Results obtained from these four groups showed that 7.6, 7.8, 35.7 and 14.9% respectively had antibody titres of 1: greater than or equal to 10. A group of travelling people, defined in the Local Government and Planning (Scotland) Act, 1982, as '...persons of nomadic habit of life, whatever their race or origin...', from Scotland were also surveyed and 28% of this group had antibodies of 1: greater than or equal to 10. Individuals in this latter group were reported to have minimal contact with cats because of their lifestyles. The prevalences of the travelling people were analysed by age group and showed no correlation with age, but other groups did show an increasing prevalence with age. The significance of these results is discussed.

Adolescent↗
PubMed1979

Classic migraine with cerebral cortical infarction causing permanent hemianopia.

A patient with typical classic migraine, including clear-cut visual auras, who had been followed up clinically for more than 15 years developed permanent right homonymous hemianopia. The underlying cause of this clinical syndrome was established by computerized axial tomography as vascular infarction or ischemia, involving the contralateral visual cortex.

Cerebral Infarction↗
PubMed1976

Effects of nicotine on rebound excitation of guinea-pig small intestine.

Poststimulus rebound contractions and associated action potentials of the circular muscle layer occurred after termination of transmural electrical stimulation. Low concentrations of nicotine (1 x 10(-6) to 5 x 10(-6) g/ml) either abolished or greatly reduced the poststimulus response. The contractile force and time duration of the response were reduced, and the latency of the response was increased by low concentrations of nicotine. The depressant action of low concentrations of nicotine was reversed by an increase in concentration from 5 x 10(-6) to 1 x 10(-4) g/ml. The effects of low concentrations of nicotine were mimicked by 1,1-dimethyl-4-phenylpiperazinium iodide, and they were prevented by hexamethonium, pentolinium, gallamine and large concentrations of atropine. Gallamine increased myogenic electrical and mechanical activity and potentiated the poststimulus rebound response. Pretreatment with guanethidine produced a small reduction in the inhibitory action of nicotine. Propranolol and phentolamine suppressed the poststimulus response, but the specificity of the action was questionable. The effects of nicotine may be mediated by excitation of intrinsic inhibitory neurons.

Action Potentials↗