Air quality and respiratory disease in Newcastle, New South Wales

OBJECTIVE

To investigate respiratory illnesses in the Newcastle region, their change over time, and their geographic relationship to industrialised areas.

DESIGN

We analysed admissions to public hospitals by postcode area in the Newcastle region, for all causes and for all the various respiratory causes, for the years 1979-1988. Comparisons were made between the State of New South Wales and the Newcastle area, and between geographic areas within Newcastle. Changes over the 10-year period were noted.

RESULTS

For both all causes and respiratory causes, admission rates to Newcastle hospitals, 1979-1988, were significantly lower than those for the rest of New South Wales in 1986. There was a correlation between living in the industrial part of the city and hospital admission for all causes and respiratory causes. There was also a correlation between mean disposable family income and hospital admissions, with those areas with the higher incomes having lower admission rates. Over the 10 years studied there was a statistically significant decline in admissions for respiratory causes, both in absolute terms and after controlling for changes in admissions for all causes. In children aged 0-14 years a significant increase in admissions for asthma occurred between 1979 and 1988, which could not be explained by diagnostic shift.

CONCLUSIONS

On the basis of hospital statistics, the members of the Newcastle population seem little different from those in the remainder of New South Wales. From 1979-1988, the efforts by industry, with the support of the community, to reduce industrial pollution have been accompanied by a reduction in hospital admission rates for respiratory diseases in general and for chronic obstructive lung disease in older people. Other contributing factors include reduced smoking rates and improved medical management. Correlations between geographic location and respiratory admission rates may be a manifestation of social class rather than poor air quality, although a contribution from the latter cannot be discounted. A concomitant rise in asthma admission rates in children aged 0-14 is likely to be unrelated to any change in air quality.

Protective immunization with invariant peptides of the Plasmodium falciparum antigen MSA2

Three octapeptides from the N and C terminal C regions of the merozoite surface Ag 2 (MSA2) of Plasmodium falciparum elicit anti-MSA2 antibody when given as diphtheria toxoid conjugates. These antibodies also bind to the MSA2 homolog from the rodent malaria Plasmodium berghei. All mice vaccinated with these conjugates and challenged with an otherwise lethal inoculum of P. berghei showed substantial protection with most surviving. There was a inverse correlation between the development of the parasitemia and the antibody titer, with alum, algammulin, and CFA giving comparable results. These observations show that the conserved region of MSA2 could form the basis of a malaria vaccine when presented in a suitably immunogenic form, thus avoiding the problems of antigenic diversity [corrected].

Protective immunization with invariant peptides of the Plasmodium falciparum antigen MSA2

Three octapeptides from the N and C terminal C regions of the merozoite surface Ag 2 (MSA2) of Plasmodium falciparum elicit anti-MSA2 antibody when given as diphtheria toxoid conjugates. These antibodies also bind to the MSA2 homolog from the rodent malaria Plasmodium berghei. All mice vaccinated with these conjugates and challenged with an otherwise lethal inoculum of P. berghei showed substantial protection with most surviving. There was a inverse correlation between the development of the parasitemia and the antibody titer, with alum, algammulin, and CFA giving comparable results. These observations show that the conserved region of MSA2 could form the basis of a malaria vaccine when presented in a suitably immunogenic form, thus avoiding the problems of antigenic diversity [corrected].

Immunological fine structure of the variable and constant regions of a polymorphic malarial surface antigen from Plasmodium falciparum

The 51-kDa merozoite surface antigen MSA2 of Plasmodium falciparum shows considerable strain-dependent polymorphism. Although marked sequence variation occurs in the central region of the molecule, the N and C-terminal sequences are highly conserved. A number of monoclonal antibodies directed against MSA2 have been described which inhibit parasite growth in vitro, but these are all directed against variable regions. In an attempt to raise strain independent antibodies we have prepared peptide-diphtheria toxoid (DT) constructs from 36 N-terminal octapeptides spanning the constant region and extending into the variable region of the FCQ/27 PNG variant staggered by one amino acid at either end. Similarly, we prepared 26 C-terminal octapeptides spanning the C-terminal constant region as well as 10 octapeptides from the variable region of the Indochina I variant MSA2. Most of the peptides elicited antipeptide titres in excess of 1/10(4) when administered to mice as peptide-DT adducts emulsified with Freund's complete adjuvant. Only 3 of the 43 N- and C-terminal constant region peptides elicited antibodies which reacted appropriately on immunofluorescence (IFA) or immunoblotting analysis with the intact MSA2 of both strains studied (FCQ/27 and Indochina I), whereas 3 other peptides from the variable region elicited antibodies reactive with the parent MSA2 only. Peptide constructs eliciting antibodies recognising the intact protein corresponded to elements in the cognate sequence of high antigenicity as predicted by the Jameson and Wolf algorithm.

Ethanol euthanasia and its effect on the binding of antibody generated against an immunogenic peptide construct

Mice were immunised with an immunogenic peptide construct CKNNNSTNSGI coupled to diphtheria toxoid as a carrier. This peptide sequence contains the epitope STNS which is the target of inhibitory monoclonal antibodies directed against the second merozoite surface antigen of Plasmodium falciparum. Antisera raised against the peptide construct were taken using an injection of 70 per cent ethanol or sodium pentobarbitone as methods of euthanasia and these methods compared by determining their effects on the binding specificity of the antibody to the antigen using the immunological criteria of immunofluorescence, immunoblotting criteria of immunofluorescence, immunoblotting and ELISA assays. There was no significant decrease in antibody binding with either sodium pentobarbitone, or ethanol with a final concentration of less than 30 per cent in mouse antisera. Antisera with an added ethanol concentration of 40 to 60 per cent relaxed antibody conformation and this raises the possibility of using the differential effects of ethanol as a tool in mapping antigenic fine structure of a range of antibodies directed against defined epitopes. The cross-reactive response of non-specific antibodies in polyclonal antisera was lowered at the suggested dosage for ethanol euthanasia. Ethanol has immense potential as an alternative method of euthanasia when barbiturate drugs, such as sodium pentobarbitone, are unavailable in specific experimental protocols. This may especially aid research workers in developing countries involved in vaccine development, antibody production and subsequent serological analysis.

High-titer antisera production using three adjuvants and peptide conjugates derived from malarial surface antigen MSA-2

We have identified a 51-kDa glycosylated myristoylated merozoite surface antigen as the target of a number of monoclonal antibodies that inhibit P. falciparum invasion. This antigen has been shown to exist in a limited number of strain-specific forms, but despite wide variation in the sequences of the internal repeat regions both N- and C-terminal elements of the protein are almost totally conserved. Accordingly, we prepared a large number of overlapping peptide constructs and demonstrated that one peptide, SNTFINNA (E-71), from the N-terminus and two peptides, QHG HMHGS (G-5) and NTSDSQKE (G-12), from the C-terminus were capable, when suitably conjoined to carrier protein diphtheria toxoid, of eliciting antibodies reactive with MSA-2 from diverse strains of P. falciparum. Here we compared the immunogenicity of the peptide constructs when formulated with a Freund's adjuvant, alum and algammulin. Both peptide constructs E-71 and G-5 elicit high-titer antibodies with all three adjuvants when tested by ELISA against the immunogens themselves and by Western blotting of whole parasite extracts from two distinct parasite strains.

[Comparative analysis between the circumoval precipitin test and ELISA with raw antigens for the diagnosis of schistosomiasis in Venezuela]

Schistosomiasis has special characteristics in Venezuela, since the majority of the infected population is asymptomatic and the elimination of eggs is very low, difficulting in this way parasitologic diagnosis. It is thus necessary to develop sensitive and specific immunologic methods to be applied in field surveys. The present study compares two serologic tests for Schistosomiasis, the enzyme linked immunosorbent assay (ELISA) with eggs (SEA) and adult (AWA) antigens and the traditional circumoval precipitation test (COPT). Sensitivity and specificity of the test were performed being 100% and 92% in COPT, 79% and 71% in ELISA-SEA and 71% and 91% in ELISA-AWA respectively. Advantages and disadvantages of each test are discussed.

Comparative immunogenicity of free and carrier-conjugated peptides derived from the constant regions of a polymorphic malarial surface antigen

One peptide (L7) representing the entire constant N-terminal region, and two peptides (L5 and L6) representing the entire C-terminal constant region of the variable merozoite surface antigen MSA2, were synthesised by solid-state (tBOC) chemistry. Mice were immunised with the peptides alone and conjoined to the carrier protein diphtheria toxoid (DT) using the hetero-bifunctional reagent maleimidocaproyloxysuccinimide (MCS). Immune response was evaluated against the peptide itself by ELISA and against the intact protein MSA2 by immunoblotting and immunofluorescence assay (IFA). Whereas all peptides elicited a strong specific antipeptide response when administered as conjugates only L7 and L6 elicited an anti-peptide response in the absence of carrier. L5 and L7 conjugates elicited sera reactive with the intact MSA2, whereas only L7 elicited such specificity in the absence of carrier.

Variable linking region immunogenicity using malarial peptide carrier protein conjugates of defined composition

Thirty-five overlapping peptides from both conserved and variable parts of the N-terminal region of a malarial merozoite surface antigen (MSA2) were synthesised using solid phase chemistry. All peptides were synthesised with an added N-terminal cysteine and purified by reverse-phase HPLC to facilitate coupling to a carrier protein diphtheria toxoid (DT) using the hetero-bifunctional reagent maleimidocaproloxysuccinimide (MCS). Mice were immunised with these peptide-DT conjugates using Freund's complete adjuvant (FCA). The immune response of these mice was tested against peptide hapten, carrier protein (DT) and the linking region itself, using enzyme-linked immunoassay (ELISA). Although there was great variation in the immune response to each part of the immunogen construct, no significant correlation could be seen between each set of responses.

The role of handwashing in prevention of endemic intensive care unit infections

Handwashing is believed to be the most important means of preventing nosocomial infections. Previous studies of healthcare workers (HCWs) have shown that handwashing practices are poor. No one has shown that handwashing practices can be easily improved and that this prevents endemic (nonepidemic) nosocomial infection. Handwashing and infection rates were studied in two intensive care units (ICUs) of a community teaching hospital. Handwashing rates were monitored secretly throughout the study. After six months of observation, we started interventions to increase handwashing. Handwashing increased gradually, but overall rates before (22.0%) and after (29.9%) interventions were not significantly different (p = .071). Handwashing never occurred before intravenous care, whereas it occurred 67.5% for all other indications (p less than .0001). When questioned, nurses felt they were washing appropriately nearly 90% of the time. Infection rates seemed unrelated to handwashing throughout the study, and no clusters of infection were detected. We conclude that handwashing rates, when measured against arbitrary but reasonable standards, are suboptimal, difficult to change and not closely related to evidence of cross-infection. Further, nurses wash hands selectively, depending on the indication for handwashing, and generally believe they are washing much more frequently than an objective observer believes they are.

Peptide vaccines derived from a malarial surface antigen: effects of dose and adjuvants on immunogenicity

Peptides P2122 (CKNNNSTNSGI) and P513 (CSQRSTNSAST) containing an epitope of a malarial surface antigen (MSA2) recognised by inhibitory monoclonal antibodies were conjugated to diphtheria toxoid (DT) protein and formulated with various gel-based and water in oil emulsion adjuvants in vaccine trials in mice and rabbits. The P2122-DT construct was effective in raising antibodies reactive with both the immunising peptide and the native antigen. Effective adjuvanticity as measured by the titre of the anti-peptide or anti-protein response in mice varied in the order: Algammulin, Montanide ISA 50 greater than or equal to Freund's adjuvant, Montanide ISA 708, 721, 70 much greater than alum, Squalene Arlacel greater than SAF-1. A similar order of adjuvant efficacy: Freund's greater than alum greater than Squalene Arlacel greater than SAF-1, was observed in rabbits.

The use of maleimidocaproyloxysuccinimide to prepare malarial peptide carrier immunogens. Immunogenicity of the linking region

Malarial peptides synthesized with an added N terminal cysteine were conjugated to purified diphtheria toxoid (DT) protein using the bifunctional reagent maleimidocaproyloxysuccinimide (MCS). The molar ratio of peptide to carrier was determined by subtractive sulphydryl titration and confirmed by sodium dodecyl sulphate (SDS) electrophoresis. For enzyme-linked immunoabsorbent (ELISA) analysis of sera from animals immunized with the DT conjugates, peptides were conjugated to bovine serum albumin (BSA) using MCS as well as a glutaraldehyde based coupling procedure. Western blotting analysis shows that both DT and BSA adducts were recognized by monoclonal antibodies (Mabs) directed against the peptide epitopes in the native sequences. Animals immunized with the DT-peptide conjugates produced antibodies to the coupling reagent (MCS) as well as diphtheria toxoid and peptide specific antibodies. This MCS specificity could be largely abolished by pre-incubation of sera with a soluble MCS homologue, a thiosuccinimidocaproylamide (TSC).