Associations between health literacy and patient outcomes in adolescents and young adults with cystic fibrosis

BACKGROUND

Interactive health literacy (HL) skills enable individuals to participate more fully in healthcare activities and play a role in improving their outcomes. We examine the associations between HL and cystic fibrosis (CF) outcomes and compare HL in a sample from both the Irish CF and general populations.

METHODS

A total of251 CF Registry participants aged 13-30 years completed the HLS-EU-Q16 survey and a disease-specific instrument for measuring quality of life (QoL) in CF. Health outcome and healthcare resource utilization (HCRU) data were sourced from the registry. CF patient outcomes were examined using generalized linear models (GLMs) with interactive HL categorization included as a factor. General population interactive HL data are from the 2011 European HL Survey (HLS-EU). Interactive HL in 180 age-sex matched CF and general population individuals was examined using a GLM with study population, sex and educational level included as factors and age as a covariate.

RESULTS

Sufficient interactive HL (total sum score ≥13) was self-reported by 81.7% of individuals with CF. Sufficient HL was associated with fewer outpatient visits [7.02(SD = 6.7: 7.4) vs. 8.74(SD = 7.9: 9.6), P < 0.001], days hospitalized [10.25(SD = 9.8: 10.7) vs. 12.8(SD = 11.8: 13.9), P < 0.001], days on intravenous antibiotics [15.3(SD = 14.7: 15.8) vs. 19.7(18.5: 21.1), P < 0.001], days on oral antibiotics [27.4(SD = 26.7: 28.1) vs. 48.48(38.7: 42.4), P < 0.001] and better QoL [77.1(SD = 75.4-78.9) vs. 64.6(60.8-68.3), P < 0.001]. Mean HL scores in CF and general populations were sufficient, although higher among individuals with CF (14.3 vs. 13.1, P < 0.01).

CONCLUSION

CF adolescents and young adults with sufficient levels of HL to obtain, understand, appraise and apply health information have better health-related outcomes.

Estimating Direct Cost of Cystic Fibrosis Care Using Irish Registry Healthcare Resource Utilisation Data, 2008-2012

BACKGROUND

Understanding the determinants of cost of cystic fibrosis (CF) care and health outcomes may be useful for financial planning for the delivery of CF services. Registries contain information otherwise unavailable to healthcare activity/cost monitoring systems. We estimated the direct medical cost of CF care using registry data and examined how cost was affected by patient characteristics and CF gene (CF Transmembrane Conductance Regulator [CFTR]) mutation.

METHODS

Healthcare resource utilisation data (2008-2012) were obtained for CF patients enrolled with the Irish CF Registry by 2013 from linked registry and national hospitalisation database records. Mean annual hospitalisation and medication per-patient costs were estimated by demographic profile, CFTR mutation, clinical status, and CF co-morbidity, and were presented in 2014 euro values. A mixed-effects regression model was used to examine the effect of demographic, CFTR mutation, and clinical outcomes on the log₁₀ cost of direct medical CF care.

RESULTS

Using 4261 observations from 1100 patients, we found that the median annual total cost per patient increased over the period 2008-2012 from €12,659 to €16,852, inpatient bed-day cost increased from €14,026 to €17,332, and medication cost increased from €5863 to €12,467. Homozygous F508-CFTR mutation (class II) cost was highest and milder mutation (class IV/V) cost was 49% lower. Baseline estimated cost in 2008 for a hypothetical underweight, homozygous F508del-CFTR 6-year-old female without chronic Pseudomonas aeruginosa/Staphylococcus aureus, CF-related diabetes (CFRD) or methicillin-resistant S. aureus (MRSA), and with a poor percent predicted forced expiratory volume in 1 s (ppFEV₁) was €10,113, and was €21,082 in a 25-year-old with the same hypothetical profile. Chronic P. aeruginosa infection increased baseline cost by 39%, CF co-morbidity diabetes by 18%, and frequency of pulmonary exacerbation by 15%. Underweight, declining ppFEV₁, chronic S. aureus colonisation, and time also influenced cost.

CONCLUSIONS

CFTR mutation is an important factor influencing the cost of CF care. Costs differ among cohorts of CF patients eligible to access new and emerging CFTR repair therapies. These findings support the evaluation of outcome-associated cost in CFTR mutation-specific CF patient groups.

Fasting plasma glucose as initial screening for diabetes and prediabetes in irish adults: The Diabetes Mellitus and Vascular health initiative (DMVhi)

Objective

Type 2 diabetes has a long pre clinical asymptomatic phase. Early detection may delay or arrest disease progression. The Diabetes Mellitus and Vascular health initiative (DMVhi) was initiated as a prospective longitudinal cohort study on the prevalence of undiagnosed Type 2 diabetes and prediabetes, diabetes risk and cardiovascular risk in a cohort of Irish adults aged 45-75 years.

Research Design and Methods

Members of the largest Irish private health insurance provider aged 45 to 75 years were invited to participate in the study. Exclusion criteria: already diagnosed with diabetes or taking oral hypoglycaemic agents. Participants completed a detailed medical questionnaire, had weight, height, waist and hip circumference and blood pressure measured. Fasting blood samples were taken for fasting plasma glucose (FPG). Those with FPG in the impaired fasting glucose (IFG) range had a 75gm oral glucose tolerance test performed.

Results

122,531 subjects were invited to participate. 29,144 (24%) completed the study. The prevalence of undiagnosed diabetes was 1.8%, of impaired fasting glucose (IFG) was 7.1% and of impaired glucose tolerance (IGT) was 2.9%. Dysglycaemia increased among those aged 45-54, 55-64 and 65-75 years in both males (10.6%, 18.5%, 21.7% respectively) and females (4.3%, 8.6%, 10.9% respectively). Undiagnosed T2D, IFG and IGT were all associated with gender, age, blood pressure, BMI, abdominal obesity, family history of diabetes and triglyceride levels. Using FPG as initial screening may underestimate the prevalence of T2D in the study population.

Conclusions

This study is the largest screening study for diabetes and prediabetes in the Irish population. Follow up of this cohort will provide data on progression to diabetes and on cardiovascular outcomes.

Validation and use of a parametric model for projecting cystic fibrosis survivorship beyond observed data: a birth cohort analysis

Background

The current lifetable approach to survival estimation is favoured by CF registries. Recognising the limitation of this approach, we examined the utility of a parametric survival model to project birth cohort survival estimates beyond the follow-up period, where short duration of follow-up meant median survival estimates were indeterminable.

Methods

Parametric models were fitted to observed survivorship data from the US CF Foundation (CFF) Patient Registry 1980–1994 birth cohort. Model-predicted median survival was estimated. The best fitting model was applied to a Cystic Fibrosis Registry of Ireland dataset to allow an evaluation of the model's ability to estimate predicted median survival. This involved a comparison of birth cohort lifetable predicted and observed (Kaplan–Meier) median survival estimates.

Results

A Weibull model with main effects of gender and birth cohort was developed using a US CFF dataset (n=13 115) for which median survival was not directly estimable. Birth cohort lifetable predicted median survival for male and female patients born between 1985 and 1994 and surviving their first birthday was 50.9 and 42.4 years respectively. To evaluate the accuracy of a Weibull model in predicting median survival, a model was developed for the 1980–1984 Cystic Fibrosis Registry of Ireland birth cohort (n=243), which had an observed (Kaplan–Meier) median survival of 27.7 years. Model-predicted median survival estimates were calculated using data censored at different follow-up periods. The estimates converged to the true value as length of follow-up increased.

Conclusions

Accurate prognostic information that is clinically critical for care of patients affected by rare, life-limiting disorders can be provided by parametric survival models. Problems associated with short duration of follow-up for recent birth cohorts can be overcome using this approach, providing better opportunities to monitor survival and plan services locally.

The stability of solitons in biomembranes and nerves

We examine the stability of a class of solitons, obtained from a generalization of the Boussinesq equation, which have been proposed to be relevant for pulse propagation in biomembranes and nerves. These solitons are found to be stable with respect to small-amplitude fluctuations. They emerge naturally from non-solitonic initial excitations and are robust in the presence of dissipation. Solitary waves pass through each other with only minor dissipation when their amplitude is small. Large-amplitude solitons fall apart into several pulses and small-amplitude noise upon collision when the maximum density of the membrane is limited by the density of the solid phase membrane.

The application of current lifetable methods to compare cystic fibrosis median survival internationally is limited

BACKGROUND

Comparing international estimates of survival can be a useful way of highlighting differences in life expectancy between cystic fibrosis (CF) populations. In this study, we compared survival in two CF populations.

METHODS

The current lifetable method takes age-specific mortality rates observed in a given year and applies them to a hypothetical population assuming those rates will remain the same in the future. This was used to compare median predicted survival in the United States (US) and the Republic of Ireland (RoI) (1986-2008). Median age at death among decedents was also examined.

RESULTS

In both countries, median age at death was lower than median predicted survival. Successive increases in annual median predicted survival were not observed; rather an overall improvement was discerned over time. In the RoI, where absolute numbers of deaths were small, year-on-year fluctuations in age-specific mortality rates resulted in wide-ranging annual median predicted survival estimates.

CONCLUSION

Median age at death is not a good measure of CF survival. Though median predicted survival improved in each country over the study period, between-country comparison at a given time point may be misleading for rare disorders like CF. Longitudinal outcomes must be examined.

Characterising transmission of a tuberculosis genotype in Scotland: a qualitative approach to social network enquiry

SETTING

Contact investigation resulting from specimens sent to the Scottish Mycobacteria Reference Laboratory.

OBJECTIVE

To characterise patients and types of exposures associated with transmission of a prevalent Mycobacterium tuberculosis genotype in Scotland.

DESIGN

A combined approach using molecular epidemiology and semi-structured patient interviews for social network enquiry.

RESULTS

We investigated social connections between 64 patients diagnosed between 1994 and 2004. Fifty-five per cent had > or = 1 identifiable contact. One third (n = 14, 32.6%) of the 43 epidemiological links detected were discerned as a result of patient interviews and were not previously recorded on surveillance reports, nor recognised by nurse specialists (all were non-household contacts). Sixteen putative sites of exposure were identified, 11 were public houses. Rather than a single-source outbreak, eight pockets of transmission were identified, the largest involving UK-born alcohol-misusing males frequenting several public houses.

CONCLUSIONS

Using a standardised approach to explore themes around which individuals may have been exposed to TB resulted in the detection of previously unrecognised epidemiological links. Epidemiological data obtained from cluster investigations, e.g., risk and social behaviours that increase the risk of infection and sites of putative exposure, can enhance the development of more appropriate questions for the contact tracing interview.

Tuberculosis outbreak associated with a mosque: challenges of large scale contact tracing

In this report, we describe the investigation and management of an outbreak of TB associated with a mosque in Scotland, and consider the implications of large-scale TB contact tracing. In 2005, an Algerian man living in the north-east of Scotland was found to be sputum smear-positive for TB. Initial investigation identified three (18.8%) close contacts with active disease. Due to the high rate of transmission, contact tracing was extended to casual contacts of the index case at a mosque. No sub-group at highest risk of exposure could be defined at the mosque. Screening of mosque attendees identified two cases (0.53%), with a further two identified by review of existing cases and enhanced surveillance. Two additional cases were linked to the outbreak by genetic profile. Response to the screening exercise was initially poor, but after modification of the communication strategy, 438 people were offered screening with 86% attending. The investigation and management of a TB outbreak is challenging and requires a complex message about risk to be communicated. In a mosque setting, there were additional complexities that, to the best of our knowledge, have not been reported previously. It was crucial, in designing the communication strategy, to identify key individuals within the community to assist with tailoring the message to address risk perception and to help to deliver the message. Despite this, approximately 50% of those considered to have the highest exposure (adult males regularly attending Friday lunchtime prayer meetings) did not come forward for screening. The screening of casual contacts in this setting was complex and time-consuming with a low detection rate.

Tuberculosis outbreak associated with a mosque: challenges of large scale contact tracing

In this report, we describe the investigation and management of an outbreak of TB associated with a mosque in Scotland, and consider the implications of large-scale TB contact tracing. The screening of casual contacts in this setting was complex and time-consuming with a low detection rate.

Citation networks in high energy physics

The citation network constituted by the SPIRES database is investigated empirically. The probability that a given paper in the SPIRES database has k citations is well described by simple power laws, P(k) proportional to k(-alpha), with alpha approximately 1.2 for k less than 50 citations and alpha approximately 2.3 for 50 or more citations. A consideration of citation distribution by subfield shows that the citation patterns of high energy physics form a remarkably homogeneous network. Further, we utilize the knowledge of the citation distributions to demonstrate the extreme improbability that the citation records of selected individuals and institutions have been obtained by a random draw on the resulting distribution.

Products of random matrices

We derive analytic expressions for infinite products of random 2 x 2 matrices. The determinant of the target matrix is log-normally distributed, whereas the remainder is a surprisingly complicated function of a parameter characterizing the norm of the matrix and a parameter characterizing its skewness. The distribution may have importance as an uncommitted prior in statistical image analysis.

Lieb mode in a quasi-one-dimensional bose-einstein condensate of atoms

We calculate the dispersion relation associated with a solitary wave in a quasi-one-dimensional Bose-Einstein condensate of atoms confined in a harmonic, cylindrical trap in the limit of weak and strong interactions. In both cases, the dispersion relation is linear for long-wavelength excitations and terminates at the point where the group velocity vanishes. We also calculate the dispersion relation of sound waves in both limits of weak and strong coupling.

Genetic survival analysis of age-at-onset of bipolar disorder: evidence for anticipation or cohort effect in families

Age-at-onset (AAO) in a number of extended families ascertained for bipolar disorder was analysed using survival analysis techniques, fitting proportional hazards models to estimate the fixed effects of sex, year of birth, and generation, and a random polygenic genetic effect. Data comprised the AAO (for 171 affecteds) or age when last seen (ALS) for 327 unaffecteds, on 498 individuals in 27 families. ALS was treated as the censored time in the statistical analyses. The majority of individuals classified as affected were diagnosed with bipolar I and II (n = 103) or recurrent major depressive disorder (n = 68). In addition to the significant effects of sex and year of birth, a fitted 'generation' effect was highly significant, which could be interpreted as evidence for an anticipation effect. The risk of developing bipolar or unipolar disorder increased twofold with each generation descended from the oldest founder. However, although information from both affected and unaffected individuals was used to estimate the relative risk of subsequent generations, it is possible that the results are biased because of the 'Penrose effect'. Females had a twofold increased risk in developing depressive disorder relative to males. The risk of developing bipolar or unipolar disorder increased by approximately 4% per year of birth. A polygenic component of variance was estimated, resulting in a 'heritability' of AAO of approximately 0.52. In a family showing strong evidence of linkage to chromosome 4p (family 22), the 'affected haplotype' increased the relative risk of being affected by a factor of 46. In this family, there was strong evidence of a time trend in the AAO. When either year of birth or generation was fitted in the model, these effects were highly significant, but neither was significant in the presence of the other. For this family, there was no increase in trinucleotide repeats measured by the repeat expansion detection method in affected individuals compared with control subjects. Proportional hazard models appear appropriate to analyse AAO data, and the methodology will be extended to map quantitative trait loci (QTL) for AAO.

Random matrix theory and acoustic resonances in plates with an approximate symmetry

We discuss a random matrix model of systems with an approximate symmetry and present the spectral fluctuation statistics and eigenvector characteristics for the model. An acoustic resonator like, e.g., an aluminum plate may have an approximate symmetry. We have measured the frequency spectrum and the widths for acoustic resonances in thin aluminum plates, cut in the shape of the so-called three-leaf clover. Due to the mirror symmetry through the middle plane of the plate, each resonance of the plate belongs to one of two mode classes and we show how to separate the modes into these two classes using their measured widths. We compare the spectral statistics of each mode class with results for the Gaussian orthogonal ensemble. By cutting a slit of increasing depth on one face of the plate, we gradually break the mirror symmetry and study the transition that takes place as the two classes are mixed. Presenting the spectral fluctuation statistics and the distribution of widths for the resonances, we find that this transition is well described by the random matrix model.

Weakly interacting Bose-Einstein condensates under rotation: mean-field versus exact solutions

We consider a weakly interacting, harmonically trapped Bose-Einstein condensed gas under rotation and investigate the connection between the energies obtained from mean-field calculations and from exact diagonalizations in a subspace of degenerate states. From the latter we derive an approximation scheme valid in the thermodynamic limit of many particles. Mean-field results are shown to emerge as the correct leading-order approximation to exact calculations in the same subspace.

Airway goblet-cell mucus secretion

A mucus hypersecretory phenotype is a dominant characteristic of chronic airways diseases such as chronic bronchitis and asthma. This phenotype develops following chronic exposure of the respiratory tract to particulate matter, allergens, irritants and/or pathogens. The associated increase in the mucus-producing potential of the respiratory epithelium represents an innate host response that can be modulated by elements of the adaptive host response. Although elevation of mucus production is designed to protect the airways, increasing evidence suggests that in excess it can be detrimental to health. Considerable progress has been made over the past five years in understanding the mechanisms involved in the development and regulation of the hypersecretory phenotype. This progress has set the stage for the development of successful dedicated mucomodulatory strategies to counter the negative impact of excess mucus production in respiratory disease.

Analytical results for the interaction energy of a trapped, weakly interacting Bose-Einstein condensate

We examine the problem of a repulsive, weakly interacting and harmonically trapped Bose-Einstein condensate under rotation. We derive a simple analytic expression for the energy incorporating the interactions when the angular momentum per particle is between zero and one and find that the interaction energy decreases linearly as a function of the angular momentum in agreement with previous numerical and limiting analytical studies.

Partitioning composite finite systems

We compare different analytical and numerical methods for studying the partitions of a finite system into fragments. We propose a numerical method of exploring the partition space by generating the Markov chains of partitions based on the Metropolis algorithm. The advantages of the method for the problems where partitions are sampled with nontrivial weights are demonstrated.

Effect of salmeterol on Pseudomonas aeruginosa infection of respiratory mucosa

We have studied the effect of salmeterol on both P. aeruginosa interactions with the mucosa of nasal turbinate organ cultures and on pyocyanin-induced (20 microg/ml) and elastase-induced (100 microg/ml) damage to nasal epithelial cells. Organ cultures were exposed to salmeterol either by preincubation with 4 x 10(-7) M salmeterol for 30 min or by pipetting 20 microl of 4 x 10(-7) M salmeterol onto the organ culture surface immediately prior to bacterial inoculation. Infected organ cultures (8 h) had significantly (p < or = 0.01) increased epithelial damage, and P. aeruginosa was predominantly associated with damaged epithelium and mucus. Salmeterol significantly (p < or = 0.02) reduced epithelial damage caused by infection and the total number of adherent bacteria (p < or = 0.05), but bacterial distribution on the mucosa was unchanged. Nasal epithelial cells incubated with pyocyanin (20 microg/ml) or elastase (100 microg/ml) for 3 h had significantly (p < or = 0.05) increased cytoplasmic blebbing and mitochondrial damage versus control values. Elastase also significantly (p < or = 0.05) increased cell projection and reduced the level of ciliation. Cells preincubated with salmeterol (2 x 10(-7) M) showed a significant reduction in some features of cell damage caused by both toxins, which was inhibited by the beta2-adrenoceptor antagonist propranolol. Our results indicate that salmeterol reduces P. aeruginosa-induced damage to both organ culture and nasal epithelium.

The effect of mutations in genes required for lipopolysaccharide synthesis on Haemophilus influenzae type b colonization of human nasopharyngeal tissue

Haemophilus influenzae type b (Hib) is an upper respiratory tract commensal that can cause invasive disease, particularly in young children. Lipopolysaccharide (LPS) has been implicated as a major virulence determinant of Hib, and changes in LPS structure may influence bacterial interactions with the respiratory mucosa. We have examined the effect of variations in LPS on the interaction of Hib with human nasal turbinate tissue maintained in an organ culture model with an air-interface, by using isogenic derivatives of strains RM153 (Eagan) and RM7004 expressing truncated LPS due to mutations in genes contained within the chromosomal loci lic1 and lic2 (lic1lic2) or in the galE and galK genes (galEK). Tissue was infected with an inoculating dose of 2.3-3.3 x 10(6) colony forming units (cfu) in 2 microliters of PBS and maintained for 24 h. By scanning electron microscopy the percentage of the organ culture surface exhibiting epithelial damage increased from 5.3 +/- 1.4 in controls to 12.5 +/- 6.4-26.3 +/- 9.1 following infection, with no significant difference between parent strains and their derivatives. There was significant bacterial tropism for mucus, and to a lesser extent damaged cells, which was not influenced by the LPS phenotype. All strains caused separation of epithelial cells, adhered to non-luminal cell surfaces, and invaded the epithelium intercellularly. We conclude that Hib associated with mucus and damaged epithelium, and infrequently with normal epithelium, but changes in the LPS phenotype did not affect the interaction between Hib and the mucosal surface of human nasal turbinate tissue.

The biology of bacterial colonization and invasion of the respiratory mucosa

Despite being regularly exposed to particulate matter during breathing, which contains bacteria from the commensal flora in the nasopharynx and from the environment, the healthy lung is kept sterile by efficient defence mechanisms. Bacterial infections of the respiratory mucosa represent a dynamic interaction, to which both host and bacterial factors contribute. The abnormal host defences associated with chronic respiratory infections (e.g. cystic fibrosis and other forms of bronchiectasis) serve to emphasize their permissive role. The bacteria that cause bronchial infections possess a wide array of potential virulence factors that contribute to their pathogenicity. Many of these factors influence the mucociliary system, an important first-line defence mechanism. The multiplication, spread and persistence of bacteria within the bronchial lumen, and consequent damage to the epithelium, stimulates a chronic inflammatory response, which also impairs mucociliary clearance and damages lung tissue. A greater understanding of host-bacterial interactions during mucosal infections should in the future lead to the development of new therapies and treatment strategies.

Comparison of haemophilus influenzae type b interaction with respiratory mucosa organ cultures maintained with an air interface or immersed in medium

Haemophilus influenzae type b infection of immersed and air interface organ cultures for 24 h caused significant epithelial damage. Bacterial association with mucus, damaged epithelium, and unciliated cells was significantly higher in air interface than immersed organ cultures, and total bacterial association was 55.8 times greater. Bacteria exhibited tropism for mucus only on explants maintained with an air interface. We conclude that immersion of nasopharyngeal tissue in medium may influence bacterial interaction with the mucosal surface.

A human respiratory-tissue organ culture incorporating an air interface

The immersion of respiratory tissue in organ cultures is unphysiologic and may influence the interactions of the tissue with experimental agents. We have assessed an organ culture of human nasal turbinate tissue with an air interface by light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), with and without replacement of culture medium. Without replacement of medium, ciliary beat frequency (CBF) was normal (11.3 +/- 0.5 Hz) at 5 d, but fell significantly (p<0.05) to 7.9 +/- 0.8 Hz at 10 d. The degree of ciliation decreased significantly (p<0.05) at 4 and 10 d. Nuclear heterochromatin in all cell types was significantly (p<0.05) reduced at 5 d. Significant (p<0.05) mitochondrial abnormalities occurred in ciliated cells at 5 d and in both ciliated and unciliated cells at 10 d. With daily replacement of medium, CBF fell significantly (p<0.05) from 11.6 +/- 0.2 Hz at Time 0 to 10.6 +/- 0.3 Hz after 20 d. The proportions of ciliated and nonciliated cells did not change after 20 d, but the proportion of mucus cells was higher at 20 d (26.3 +/- 5.4%) than at Time 0 (9.8 +/- 2.7%). No mitochondrial abnormalities, changes in nuclear heterochromatin levels, or reduction in cilial density on ciliated cells were present. The amount of damaged epithelium was less at 20d (7.2 +/- 3.8%) than at Time 0 (19.0 +/- 5.8%). This model more closely reproduces physiologic conditions in vitro than do models involving the immersion of respiratory tissue in media. Its long viability will permit studies of virus and bacterial infections, and of the effects of pharmacologic agents and environmental factors.

Fabrication of a new crown and provisional to an existing removable partial denture

A method of fabricating a new crown to an existing removable partial denture is described. A press-form plastic shell made from the diagnostic cast provides the outer contours for the abutment tooth, while an acrylic resin coping is fabricated on a die to provide accurate internal adaptation. The acrylic resin coping is seated on the prepared abutment. Autopolymerizing acrylic resin is mixed and placed in the plastic shell that is then placed in the mouth over the coping, forming the acrylic resin crown pattern. The removable partial prosthesis is fitted over the crown pattern intraorally. The pattern is transferred back to the die, the margins are refined, and the casting is completed and finished, avoiding reduction of the established contours. The same plastic shell is used with tooth-shaded acrylic resin to construct a provisional crown directly in the mouth. This technique allows the patient to wear the removable partial denture while the laboratory procedures are completed.

Interaction of pneumolysin-sufficient and -deficient isogenic variants of Streptococcus pneumoniae with human respiratory mucosa

Streptococcus pneumoniae is the most common cause of community-acquired pneumonia, and pneumolysin, a hemolytic toxin, is thought to be an important virulence factor. We have studied the interaction of a pneumolysin-sufficient type II S. pneumoniae strain (PL+) and an otherwise identical pneumolysin-deficient derivative (PL-) with human respiratory mucosa in an organ culture with an air interface for up to 48 h. Ciliary beat frequency (CBF) was measured by a photometric technique, and adherence to and invasion of the epithelium were assessed by scanning and transmission electron microscopy. PL+ and PL- caused a progressive fall in CBF compared with the control which became significant (P < 0.01) at 24 h for PL+ and at 48 h for PL-. At 24 h, there was a significant increase in the percentage of the mucosa of the organ culture that was damaged for PL+ compared with the control (P < 0.01) and PL- (P < 0.02). At 48 h, there was a significant increase in mucosal damage for both PL+ (P < 0.005) and PL- (P < 0.05) compared with the control. At 24 and 48 h, PL+ and PL- adhered predominantly to mucus and damaged cells. PL+ infection alone caused separation of tight junctions between epithelial cells, and at 48 h PL+ cells were adherent to the separated edges of otherwise healthy unciliated cells. PL+ and PL- both caused damage to the epithelial cell ultrastructure. S. pneumoniae infection caused patchy damage to the respiratory mucosa and a lowered CBF. These changes were more severe and occurred earlier with the pneumolysin-sufficient variant.

The influence of teeth on denture base processing accuracy

The Michigan Computer Graphics Coordinate Measuring System was used to determine the influence of denture teeth on the accuracy of processed denture bases. Three different processing methods--compression molding, injection pressing, and vacuum-assisted resin pouring--were used. The presence of denture teeth was determined to affect the accuracy of the processed denture bases of all three techniques. For denture bases without teeth, the compression-molding technique demonstrated significant differences in accuracy; however, no significant differences were found in the injection-pressed or resin-poured denture bases.

Cystic fibrosis in the United Kingdom, 1968-1988: incidence, population and survival

A thorough survey was conducted of patients with cystic fibrosis living in the UK from 1977 onwards. This was supplemented with death certificate data back to 1968. There was one case identified for each 2475 births. The total number of cases in the UK rose linearly from 4086 in 1977 to 5426 in 1988 and is estimated to be 6000 in 1992. The probability of survival improved in the period under study for all age groups and in both sexes. It was worst in the first year of life, dropped sharply thereafter but then increased steadily with age. There has been a very marked improvement over the years in survival in the first year of life, but a lesser one in older age groups. Male mortality was greater than that in females in the first year of life, but less in subsequent years giving, overall, worse survival for females. A set of cohort and 'current' survival graphs for the two sexes are given.

In vitro phenoloxidase activity in the blood of Ciona intestinalis and other ascidians

The presence and activation of phenoloxidase in the blood of Ciona intestinalis and other ascidians was investigated in vitro. In C. intestinalis, phenoloxidase was found to exist in the cells as a proenzyme and to be activated by proteases. The microbial carbohydrates, LPS or laminarin, also enhanced enzyme activity but a similar effect was not achieved with other sugars. Calcium was not essential for enzyme activity and no enzyme suppression was seen at high calcium concentrations. Prophenoloxidase activation by LPS was further found to be dose related and inhibited by PTU and tropolone. Since benzamidine and STI reduced phenoloxidase activity in cell lysate supernatants, activation may involve other factors, possibly a serine protease. Lastly, as phenoloxidase activity was detected in the blood cells (usually the morula cells) of eight other ascidian species, it appears that it is widely distributed in the blood of this group of invertebrates.

The effect of aluminum coating on elemental standards in X-ray microanalysis

The standardisation of frozen hydrated bulk biological specimens using gelatin standards is described. The relationship between corrected elemental X-ray counts and ionic concentration was found to be linear, and minimum detectable limits for each element are stated. Variations in uncorrected standard curves were found to be due to changes in aluminium coating thickness. There was an inverse relationship between coating thickness and elemental X-ray counts. The factors causing this are discussed. To avoid errors arising from inconsistent aluminium thickness, experimental material should only be compared with standards of similar aluminium net counts. This can be achieved most easily by mounting and analysing specimen and standard together.