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Biomedical subjects

S West

Publications and source records attributed to S West.

At least 109 records · Page 6Linked to original sources
PubMed1991

Central and peripheral nervous system demyelination after infection with Mycoplasma pneumonia: evidence of an autoimmune process.

We have reported a unique case of multiple central and peripheral nervous system abnormalities after a serologically documented infection due to Mycoplasma pneumoniae. The evidence suggests that this organism is capable of causing demyelination, probably through an autoimmune process. This case may help to provide further insight into the pathogenetic mechanisms involved in other demyelinating diseases in which the triggering exogenous agent is unknown. Certainly this case demonstrated that both central and peripheral nervous system demyelination can occur and that patients with M pneumoniae infections should be observed closely for possible development of neurologic symptoms.

Adult↗
PubMed1991

Longitudinal study of the microbiology of endemic trachoma.

A longitudinal study of trachoma in 100 members of nine Tanzanian families was conducted to assess the sources of variation in the laboratory identification of trachoma and the changes that might occur over time. Multiple conjunctival swabs were collected every 3 months for 1 year and examined by direct fluorescent-antibody cytology (DFA), enzyme immunoassay, or microimmunofluorescence serology for tear antichlamydial antibodies. DFA specimens collected 5 min apart had a discordance rate of 10% and this is attributable to sampling variation. DFA specimens collected 2 days or more apart show a 25% discordance rate. This suggests a biologic variation in shedding in addition to sampling variation. Good correlation existed between the DFA and the enzyme immunoassay. Tear serology was quite specific in predicting the presence of clinical disease and correlated with the other two antigen detection tests, although it does not seem to offer any practical advantages. These studies indicate that there is considerable variation in the shedding of chlamydia by people living in trachoma-endemic areas.

Adolescent↗
PubMed1990

A multiple-staining procedure for the detection of different DNA fragments on a single blot.

We have developed a method that implies the use of a particular type of substrate which can be used in combination with alkaline phosphatase in detecting nucleic acid on filters. The method allows the detection of several different nucleic acid sequences on a single filter. In consecutive steps, the target DNA molecules are hybridized with different digoxigenin-labeled DNA probes. After each hybridization step, digoxigenin is detected with an antibody-alkaline phosphatase conjugate. This enzyme is subsequently visualized by a color reaction using different 2-hydroxy-3-naphthoic acid anilide (naphthol AS) phosphates as substrates in combination with varying diazonium salts. The multiple-staining procedure is based on the fact that the probe DNA-antibody complex can be removed while the color precipitate remains stably bound at its place on the filter. This allows several repeated hybridizations with other digoxigenin-labeled probes followed by antibody detection and color reaction with other naphthol AS phosphate-diazonium salt combinations. Aside from the ability to simultaneously visualize different target DNAs on a single filter, this new method provides several important features that are more powerful than the conventional 5-bromo-4-chloro-3-indolyl phosphate-nitro blue tetrazolium (BCIP-NBT) color reaction for alkaline phosphatase. The colors are more stable and brilliant than BCIP-NBT; their development is faster, the resolution of closely spaced bands is greater, and the background is much lower. The detection limit for alkaline phosphates is as good as with BCIP-NBT (0.1 pg of DNA). One major advantage is the simplicity of removing the colors by ethanol incubation. In this paper, the method is described using the example of Southern blotted DNA fragments.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1990

Association of nonmelanoma skin cancer and actinic keratosis with cumulative solar ultraviolet exposure in Maryland watermen.

To establish the relationship between ultraviolet-B radiation and squamous cell carcinoma (SCC), basal cell carcinoma (BCC), and actinic keratosis (AK), a cross-sectional prevalence survey was performed in a sample of 808 white, male watermen 30 years of age and older residing in the Eastern Shore of Maryland. A measure of personal cumulative ultraviolet-B exposure was determined for each subject from data collected through interviews and field and laboratory measurements. A personal interview elicited skin type, medication history, and other factors. Clinical diagnoses and histologic confirmation were done for current and previously removed skin tumors. The ratio of subjects with SCC to subjects with BCC was approximately 1:1; however, the ratio of BCC to SCC was 1.25:1 because BCC cases were more prone to multiple lesions. Watermen with SCC or AK but not BCC had higher average annual ultraviolet-B doses than age-matched controls. This was particularly marked in watermen younger than 60 years of age. Logistic regression showed that an older age, childhood freckling, and blue eyes significantly increased the risk of the development of all three types of skin tumor. Ease of sunburning was associated with BCC and AK, but not with SCC. Watermen in the upper quartile of cumulative ultraviolet-B exposure had a 2.5 times higher risk for the development of SCC when compared with the lower 3 quartiles. This suggests that high levels of ultraviolet-B exposure are important in SCC occurrence. The risk of AK developing was 1.5 times higher for those whose cumulative ultraviolet-B exposure exceeded the median. The relationship of BCC to cumulative ultraviolet-B exposure was not clear and this suggests that different etiologic mechanisms operate for SCC and BCC.

Adult↗
PubMed1990

Changing water-use patterns in a water-poor area: lessons for a trachoma intervention project.

An epidemiological survey carried out in the Dodoma region of Tanzania found that high rates of trachoma infection in pre-school children were associated with unwashed faces. Prior to a planned trachoma intervention project, a pilot study was done on household decisions about water use and perceptions about face washing and eye disease. The study found that mothers overestimated the amount of water necessary to wash a child's face. In addition, mothers would not change their water-use priorities without the consent of their husbands and the support of the community. Therefore a health education program was designed to address the perception that face washing required a great deal of water. The program also sought to involve and re-educate the whole community rather than focus only on the mothers who were most likely to wash the children's faces.

Child↗
PubMed1990

Visible light and risk of age-related macular degeneration.

Sunlight exposure has been suggested as a cause of AMD. To examine this, we collected detailed histories of ocular sun exposure in 838 watermen who work on the Chesapeake Bay. The presence and severity of AMD was assessed in stereo macular photographs. Macular changes were classified into four grades of increasing severity ranging from the presence of 5 or more drusen (AMD-1) to extensive geographic atrophy or disciform scars (AMD-4). Previously, we found no association between AMD and ocular exposure to either UV-B (290 to 320 nm) or two bands of UV-A (320 to 340 nm and 340 to 400 nm). We have undertaken further analysis to determine whether ocular exposure to violet light (400 to 450 nm), blue light (400 to 500 nm), or all visible light (400 to 700 nm) was associated with AMD. Ocular exposure was estimated using model computations of ambient irradiance and estimates of the ratio of ocular to ambient exposure. Compared to age-matched controls, established cases (AMD-4), but not milder cases, had significantly higher exposure to both blue and visible light over the preceding 20 years (Wilcoxon sign rank test, P = 0.027). There was no difference in exposure at younger ages. These data suggest that high levels of exposure to blue and visible light late in life may be important in causing AMD.

Adult↗
PubMed1990

Placental anticoagulant protein-I: measurement in extracellular fluids and cells of the hemostatic system.

Placental anticoagulant protein-I (PAP-I), a member of the lipocortin protein family, is a potent in vitro anticoagulant whose in vivo function is unknown. Very low levels of PAP-I were present in plasma of normal volunteers (0 to 5 ng/ml) and in randomly chosen plasma specimens from hospitalized patients (0 to 28 ng/ml). Review of selected hospital records did not reveal any single clinical entity that correlated with plasma levels. PAP-I was also found in amniotic fluid (12 to 107 ng/ml) and in conditioned medium of cultured endothelial cells (49 +/- 20 ng/ml). Gel filtration experiments showed that PAP-I was intact and uncomplexed in plasma and amniotic fluid. The protein was fairly abundant intracellularly: 4080 +/- 2560 ng/mg total protein in cultured umbilical vein endothelial cells; 178 +/- 109 ng/mg in platelets; 564 +/- 384 ng/mg in leukocytes; and 8.4 +/- 4.3 ng/mg in erythrocytes. The levels of PAP-I increased in platelet-rich plasma after stimulation of platelets with arachidonic acid but not after stimulation with ADP, epinephrine, thrombin, ristocetin, or collagen. These data suggest that PAP-I probably does not function as a circulating natural anticoagulant in normal persons.

Amniotic Fluid↗
PubMed1990

The effect of hyperinflation on respiratory muscle work in acute induced asthma.

To examine the relationship between end-expiratory lung volume and respiratory muscle work during acute bronchoconstriction, we measured the work of breathing in nine asthmatic subjects, in whom bronchoconstriction was induced with histamine aerosol. When the forced expiratory volume in one second (FEV1) fell below 60% of the control value, work was measured at the spontaneously hyperinflated lung volume (VLS), at a volume equivalent to the control functional residual capacity (FRC) and at a volume 30% of vital capacity (VC) above the control FRC. Hyperinflation to VLS caused a 39% decrease in the total positive work per breath from 2.8 +/- 0.4 to 1.7 +/- 0.1 J, entirely due to a decrease in expiratory work per breath from 1.6 +/- 0.4 to 0.10 +/- 0.05 J. Inspiratory work did not change at any lung volume, because the increase in inspiratory elastic work due to hyperinflation was offset by the decrease in flow resistive work. Breathing above VLS did not alter the total positive muscle work, but did increase the negative work of the inspiratory muscles from 0.4 +/- 0.1 to 0.8 +/- 0.1 J.breath. We conclude that during induced asthma spontaneous hyperinflation minimizes the total respiratory muscle work and may constitute a mechanism for minimizing energy expenditure.

Adult↗
PubMed1989

Cigarette smoking and risk of nuclear cataracts.

The current study was undertaken to assess the relationship of smoking to the risk of lens opacities. The risk was evaluated separately for nuclear and cortical opacities and for both types together. We studied 838 watermen in Maryland by detailed ocular examination for the presence and severity of each cataract type. All subjects were interviewed regarding smoking history, and a cumulative smoking dose was calculated. The results suggest a significantly increased risk of pure nuclear opacities associated with cigarette smoking. The increase in smoking dose was associated with increasing severity of nuclear opacity. The risk of nuclear opacities increased with increasing cigarette dose and decreased if the subject had quit smoking. The effect of smoking was most striking in those less than 80 years old. No increased risk of nuclear opacities was observed with earlier age when smoking started, after adjusting for dose and cessation of smoking. Further investigations are warranted on the biochemical and physical damage to the nucleus of the lens from smoking cigarettes.

Adult↗
PubMed1989

A cost-effectiveness analysis of a simple micromethod for hepatitis B screening in hepatitis B virus control programmes.

We developed a simple micromethod for identifying mothers who are most likely to transmit hepatitis B infection to their infants, using reverse passive haemagglutination for detecting HBsAg (hepatitis B surface antigen) in capillary blood. This screening method was evaluated against other strategies for hepatitis B control by means of decision- and cost-effectiveness analyses. The micromethod was shown to be cost-effective when the cost of hepatitis B vaccine was high. However, with increasingly reduced costs of the vaccine, it may have a limited role in a programme of mass immunization for hepatitis B.

Carrier State↗
PubMed1989

The lack of long-term suppressive effect of ciprofloxacin on murine bone marrow.

In order to investigate the long-term effect of therapy with ciprofloxacin on haemopoietic cells, we administered ciprofloxacin orally in a daily dosage of 150 mg/kg/day in three divided doses for 11 days to syngeneic mice. A control group of mice was treated with saline. On the second, sixth, tenth and sixteenth day of ciprofloxacin therapy complete blood counts (cbc) and determination of haemopoietic progenitor cells (cfu-gm) from the tibial and femoral bone marrow were performed and followed by the transplantation of the bone marrow into lethally irradiated syngeneic mice. Bone marrow engraftment was evaluated ten days following transplantation by counting the visible colonies formed on the spleen surface (cfu-s) and by measuring the incorporation of 125I by the spleen and by the femurs of the transplanted mice. The results revealed that there was no statistical significance between the control and the ciprofloxacin treated mice in cbc, cfu-gm and cfu-s parameters. It is concluded that the suppressive effect of ciprofloxacin on haemopoietic cells appears only with very high concentrations of ciprofloxacin and is short-term and reversible.

Animals↗
PubMed1989

Overwhelming pneumococcal bacteraemia in systemic lupus erythematosus.

An 18 year old woman presented with fulminant pneumococcal bacteraemia and subsequently died with multisystem organ failure. A search for diseases predisposing to overwhelming encapsulated bacterial infections was negative except for previously undiagnosed systemic lupus erythematosus (SLE). This case emphasises the severity of immune system dysfunction in some patients with SLE, regardless of immunosuppressive treatment. The possible relation between Fc receptor dysfunction and pneumococcal bacteraemia in SLE is discussed.

Adolescent↗
PubMed1989

The epidemiology of infection in trachoma.

Specimens for chlamydial isolation culture and direct fluorescent antibody cytology (DFA) were collected from 1671 women and children from a trachoma-endemic area in Central Tanzania. Trachoma was graded using the new World Health Organization grading scheme, and 54% of the children and 9% of the women had inflammatory trachoma (TF or TI). DFA, using the presence of five elementary bodies as the criterion for a positive test, had a sensitivity of 88.0% and a specificity of 87.5% compared to culture and a sensitivity of 54.7% and specificity of 92.8% compared to clinical diagnosis. Altogether, 52.9% of those with trachoma grade TF were positive on either or both culture and DFA versus 77.0% of those with TI. Twenty-nine isolates were serotyped; 18 were serovar A, ten were serovar B, and one was serovar Ba. Positive cultures or DFA were obtained in 6.9% of those graded clinically as not having TF or TI and in a smaller number of those without any perceptible evidence of disease. Conversely, organisms could not be demonstrated in a number of people with severe inflammation (TI) even though some became positive after multiple repeated culture. These two findings of infection without disease and disease without evidence of infection suggest the importance of the immunologic response to infection in determining the clinical status. DFA was found to be an appropriate test for future field studies of trachoma. Further studies of those with disease but without agent and of those with agent but without disease will help understand the dynamics of infection and transmission and the role of the immune response in this important blinding disease.

Adolescent↗
PubMed1989

Water availability and trachoma.

As part of an epidemiological survey of risk factors for trachoma in 20 villages in the United Republic of Tanzania, we investigated the relationship of village water pumps, distance to water source, and quantity of household water to the risk of inflammatory trachoma. We also evaluated whether there was an association between the cleanliness of children's faces and these water variables. No association was found between the presence of a village water supply and the prevalence of trachoma. However, the risk of trachoma in the household increased with the distance to a water source--although there was no association with the estimated daily amount of water brought into the house. Likewise, children were more likely to have unclean faces if they lived more than 30 minutes from a water source, but whether they had clean faces was not associated with the daily quantity of water brought into the household. The effect of the distance to water supply on trachoma may well reflect the value placed on water within the family, and this determines the priority for its use for hygiene purposes. The results of the study suggest that changing the access to water per se may be insufficient to alter the prevalence of trachoma without also a concomitant effort to change the perception of how water should be utilized in the home.

Child↗