Awareness and Preventative Behaviours Regarding Toxoplasma, Listeria and Cytomegalovirus Among Pregnant Women

Aim Infection with toxoplasma, listeria and cytomegalovirus (CMV) infections can negatively affect pregnancy outcomes. Awareness of these infections, knowledge of preventive practices and pertinent behaviours was assessed. Methods A survey of patients at antenatal clinics in a Dublin maternity hospital was conducted over a six month period. Analysis was undertaken using SPSS. Results The response rate was 36% (287/800). One in two respondents were aware of toxoplasma, one in four of Listeria but only 1 in 10 of CMV. Overall, knowledge was highest among older, more educated pregnant women. Nativity had a significant effect on knowledge and behaviour, but increasing parity did not. However the majority practised key safe behaviours. Conclusion Information must be conveyed to pregnant women in a user friendly format and in a culturally sensitive way.

Is Increasing Life Expectancy Leading To More Complexity?

Life expectancy is increasing in Ireland, but whether this has resulted in healthier life years among the elderly and its impact (if any) on hospital services is unknown. The purpose of the study was to use routinely available data to explore the relationship of age and indicators of clinical complexity in acute hospitals over ten years. The study included all in-patients aged 65+ years from the Hospital In-Patient Enquiry (HIPE) discharged between 2005 and 2014. Indicators of complexity included the Charlson index, overall length of stay (LOS), intensive care unit LOS and deaths in hospital, analysed by the major clinical classification software (CCS). Over the period, the number and rate of admissions increased, especially among those aged 85+. Indicators of patient complexity increased and LOS decreased. In-hospital mortality decreased from 5.9% to 4.7%. Hospitals appear to be managing the emergency care of the older and more complex patient more efficiently and with better outcomes.

Potential role of asymptomatic kitchen food handlers during a food-borne outbreak of norovirus infection, Dublin, Ireland, March 2009

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IL-10 and TGF-beta1 are associated with variations in fluke burdens following experimental fasciolosis in sheep

Infection with Fasciola hepatica causes an economically important disease in ruminants. Variability in parasite load may indicate innate differences in the host immune system. This study aimed to investigate the immunological mechanisms that are associated with variability in parasite burden following experimental F. hepatica infection in cross-bred sheep. Of a total of 16 animals, four were randomly chosen as uninfected controls, and the remainder infected with 100 viable metacercariae. Uninfected animals were used as the control group for evaluation of cytokine gene expression levels. For comparative analysis, specific animals were selected on the basis of extremes of fluke burdens, and were categorised into light (n = 4) and heavy burdened (n = 3) cohorts. Serum antibody levels, haematological parameters, and expression of IL-4 and IFN-gamma genes in hepatic lymph nodes were equivalent in both groups. However, significant differences in mitogen-specific lymphocyte proliferation in vitro and in expression of TGF-beta1 and IL-10 genes in hepatic lymph nodes were observed at acute and chronic phases of infection, respectively. These results provide useful information in developing further understanding of natural resistance to fasciolosis in sheep.

Detection of genes with moderate effects on disease resistance using ovine mhc and resistance to nematodes as an example

Detecting some of the genes that influence disease resistance would improve our understanding of the processes that cause disease and also simplify disease control. Genes within the major histocompatibility complex (mhc) are strong candidates for disease resistance and they have been intensely studied for the last 30 years. Recently, several groups working independently have reported the existence of alleles within the mhc that are associated with enhanced resistance to nematode infection. This article uses hindsight to describe some of the potential pitfalls that hinder the search for valid disease resistance genes. The search requires a good understanding of disease biology, molecular genetics, statistical genetics and especially, the design and analysis of experiments. The power to detect mhc effects is quite low and is quite sensitive to the frequency of the putative resistance alleles.

Breed differences in mucosal and systemic antibody response to nematode infection in sheep: an important role for IgE?

This study compared the immunological and biochemical responses of co-grazed Suffolk and Texel lambs to a natural gastrointestinal nematode infection. Variables analysed included serum pepsinogen, total protein, albumin, haematological variables and nematode-specific serum immunoglobulin activity, at 11, 14 and 17 weeks of age. At 17 weeks, randomly selected lambs were necropsied to determine worm burdens, nematode-specific mucosal abomasal and intestinal immunoglobulin activity. Nematode burden, faecal egg count and pepsinogen concentrations were significantly higher in Suffolks relative to Texels, at all 3 time-points investigated. Suffolks displayed significantly higher erythrocyte, total leukocyte, lymphocyte and neutrophil counts, mean cell volume and packed cell volume, than Texels (P<0·01). However, breed differences in eosinophil counts were not significant. While serum nematode-specific antibody activity levels were significantly higher (P<0·001) in Texels for all isotypes measured, antibody activity levels at a mucosal level were equivalent in both breeds. Correlation analysis of mucosal antibody levels and nematode variables highlighted a more consistent pattern of events in Texels, with more mucosal antibodies negatively correlated with FEC and worm burden, in comparison to Suffolks. In particular, an important role for mucosal IgE is proposed. In Texels, a significant and negative correlation was identified between IgE and faecal egg counts and worm burden (FEC: −0·48, P<0·005). This was not observed in Suffolks. The evidence suggests that susceptibility in Suffolks may be mediated through poor IgE affinity/avidity and/or through deficiencies in related mechanisms such as mast cell production, recruitment or activation.

Hepatitis A antibody prevalence among people with an intellectual disability in Ireland

This manuscript aims to determine the prevalence of antibody to and risk factors for hepatitis A virus (HAV) in individuals attending three intellectual disability services through a cross-sectional survey held in Dublin, Ireland. Participants were 636 individuals aged four to 78 years attending three intellectual disability services. The main outcome measure was the measurement of anti-HAV (IgG antibody) in oral fluid swabs using an antibody capture enzyme immunoassay (EIA) technique. Risk factor information was obtained by questionnaire from the individual’s medical record.

Haemolytic uraemic syndrome associated with interfamilial spread of E. coli O26:H11

In September 2000, haemolytic uraemic syndrome (HUS) was diagnosed in a 10-month-old child with a prodromal history of vomiting and diarrhoea (non-bloody). Investigation revealed that a self-limiting gastrointestinal illness (mean duration 48 h) had occurred among immediate and extended family in the 2 weeks prior to the child's admission. The epidemiology of the illness suggested person-to-person spread. Five children (close family contacts) had E. coli O26 verocytotoxin (VT1 and VT2) isolated from stools. Stool culture and serology from the index case were negative for shiga toxin-producing E. coli (STEC) organisms. Control measures in accordance with the Public Health Laboratory Service (PHLS), verocytotoxogenic organisms (VTEC) guidelines were applied to prevent further spread among the extended family and contacts. Despite detailed food and environmental exposure histories, the source of the illness was not identified. This incident highlights the importance of investigation of cases of post-diarrhoeal HUS, for potential shiga toxin E. coli aetiology.

Gastrointestinal nematode infection in sheep--a review of the alternatives to anthelmintics in parasite control

Efforts to curb production losses caused by nematode parasitism in sheep have led to the development of a number of control methods to complement or replace anthelmintics. The need for alternative control measures stems from the emergence of anthelmintic-resistant parasitic nematodes with reports of multi-class resistance to these drugs now emerging. A number of these control methods such as predacious microfungi, protein supplementation, plant extracts in feed and vaccines have demonstrated potential to control infection but require development and examination under natural conditions. Breeding for natural resistance to nematode infection has already shown success in controlling the disease under natural conditions. Selection for resistance is currently based on fecal egg count measurements but identification of genetic indicators of resistance will provide a more efficient method of selection. Current quantitative trait loci for nematode resistance include the MHC genes, interferon gamma gene, IgE gene and microsatellites on chromosome 1, 5 and 6. This paper reviews the current alternatives to anthelmintics to control infection, with an emphasis on breeding for host resistance and identification of genetic indicators of resistance.

Intron 1 of the interferon γ gene: Its role in nematode resistance in Suffolk and Texel sheep breeds

Genetic variation at intron 1 of the interferon gamma gene has recently been associated with variation in faecal egg count in Romney, Merino and Soay breeds of sheep. The Texel breed is more resistant to gastrointestinal nematode infection than the Suffolk breed, based on faecal egg count. Hence, the objective of this experiment was to characterise the polymorphisms of intron 1 of the interferon gammagene in Suffolk and Texel sheep, and to determine if the characterised haplotype variants were associated with faecal egg count variation in these breeds. Intron 1 haplotypes and faecal egg measurements were determined for Suffolks (n=113) and Texels (n=135). Four haplotypes were identified in Suffolks (A, B, C and D), two haplotypes as previously described, and two previously unknown haplotypes. However, there was no association between interferon gamma intron 1 haplotype and faecal egg count in Suffolks. In contrast, two previously identified haplotypes (A and B) were present in the Texel breed, and the B haplotype was associated with resistance to nematode infection (P=0.02). These results suggest that intron 1 of the interferon gamma gene has an important role in resistance to nematode infection in the Texel breed.

Epidemiological findings and medical, legal, and public health challenges of an investigation of severe soft tissue infections and deaths among injecting drug users -- Ireland, 2000

In May 2000, public health authorities in Dublin, Ireland, identified a cluster of unexplained severe illness among injecting drug users (IDUs). Similar clusters were also reported in Scotland and England. Concurrent investigations were undertaken to identify the aetiology and source of the illnesses. In Dublin, 22 IDUs were identified with injection-site inflammation resulting in hospitalization or death; eight (36%) died. Common clinical findings among patients with severe systemic symptoms included leukaemoid reaction and cardiogenic shock. Seventeen (77%) patients reported injecting heroin intramuscularly in the 2 weeks before illness. Of 11 patients with adequate specimens available for testing, two (18%) were positive by 16S rDNA PCR for Clostridium novyi. Clinical and laboratory findings suggested that histotoxic Clostridia caused a subset of infections in these related clusters. Empiric treatment for infections among IDUs was optimized for anaerobic organisms, and outreach led to increased enrolment in methadone treatment in Dublin. Many unique legal, medical, and public health challenges were encountered during the investigation of this outbreak.

Major histocompatibility complex DRB1 gene: its role in nematode resistance in Suffolk and Texel sheep breeds

A potential control strategy for nematode infection in sheep is the implementation of a breeding programme to select for genes associated with resistance. The Texel breed is more resistant to gastrointestinal nematode infection than the Suffolk breed, based on faecal egg count, and this difference should enable the identification of some of the genes responsible for resistance. The objective of this study was to determine if variation at the ovine MHC-DRB1 locus was associated with variation in faecal egg count in Suffolk and Texel sheep. Ovar-DRB1 alleles and faecal egg count were determined for Texel (n = 105) and Suffolk (n = 71) lambs. Eight Ovar-DRB1 alleles, including 1 previously unknown allele, were identified in the Texel breed by sequence-base-typing. Seven Ovar-DRB1 alleles were identified in the Suffolk breed. Two Ovar-DRB1 alleles were common to both breeds, but were among the least frequent in the Suffolk population. In the Suffolk breed 1 Ovar-DRB1 allele was associated with a decrease in faecal egg count and 2 alleles with an increase in faecal egg count. This locus accounted for 14% of the natural variation in faecal egg count in Suffolks. There was no evidence for an association between Ovar-DRB1 alleles and faecal egg count in the Texel breed and the Ovar-DRB1 locus accounted for only 3% of the phenotypic variation in faecal egg count. These results suggest that the Ovar-DRB1 gene plays an important role in resistance to nematode infection in the Suffolk breed. The difference in faecal egg counts between these breeds may be attributable in part to the different allele profile at the Ovar-DRB1 locus.

Folic acid supplements to prevent neural tube defects: trends in East of Ireland 1996-2002

Promotion of folic acid to prevent neural Tube Defects (NTD) has been ongoing for ten years in Ireland, without a concomitant reduction in the total birth prevalence of NTD. The effectiveness of folic acid promotion as the sole means of primary prevention of NTD is therefore questionable. We examined trends in folic acid knowledge and peri-conceptional use from 1996-2002 with the aim of assessing the value of this approach. From 1996-2002, 300 women attending ante-natal clinics in Dublin hospitals annually were surveyed regarding their knowledge and use of folic acid. During the period the proportion who had heard of folic acid rose from 54% to 94% between 1996 and 2002 (c2 test for trend: p<0.001). Knowledge that folic acid can prevent NTD also rose from 21% to 66% (c2 test for trend: p<0.001). Although the proportion who took folic acid during pregnancy increased from 14% to 83% from 1996 to 2002 (c2 test for trend: p<0.001), peri-conceptional intake did not rise above 24% in any year. There is a high awareness of folic acid and its relation to NTD, which is not matched by peri-conceptional uptake. The main barrier to peri-conceptional uptake is the lack of pregnancy planning. To date promotional campaigns appear to have been ineffective in reducing the prevalence of NTD in Ireland. Consequently, fortification of staple foodstuffs is the only practical and reliable means of primary prevention of NTD.

A cluster of leptospirosis cases in canoeists following a competition on the River Liffey

On 6 November 2001, a possible case of leptospirosis was notified in a canoeist following a white-water event on the River Liffey. It emerged that a second race participant was also a possible case. An outbreak control team coordinated the epidemiological investigation, laboratory investigation, environmental assessment, communication and control measures. A cluster of six laboratory-confirmed cases of leptospirosis, serologically Leptospira interrogans serogroup Icterohaemorrhagiae was found. The attack rate was 9.2% (6/65). Fever, chills, red eyes and shortness of breath were significantly associated with being a confirmed case. Five cases were hospitalized. Swallowing more than one mouthful of water was associated with an increased risk of developing leptospirosis. Increased rainfall and release of hydroelectric water may have contributed to this outbreak. A multidisciplinary approach and use of the Internet and e-mail facilitated rapid and effective communication.

Hepatitis A outbreak in an institution

In February 1996, four serologically confirmed cases of hepatitis A virus (HAV) occurred in one household. Investigation showed that the source was a family member with sub-clinical HAV who attended a Unit for Learning Disabilities. Reports of two further cases in the institution followed and control measures were instigated. Contacts were unwilling to accept human normal immunoglobulin (HNIG). Following salivary antibody and serological testing, hepatitis A vaccine was offered to the non-immune. An investigation found that sub-clinical infection was significantly associated with being less than 5 years old (RR = 6.07, p < 0.005) and being in one particular classroom (RR = 6.21, p < 0.0005). None of the staff in the institution became infected. In all, 31 cases of hepatitis A (18 clinical and 13 subclinical cases) occurred. This paper (a) describes an outbreak of hepatitis A (b) refers to the use of a salivary antibody test (assay performance to be published elsewhere) (c) identifies factors associated with the acquisition of HAV and (d) endeavours to assess the effectiveness of the vaccine to contain the outbreak.

Determinants of folic acid knowledge and use among antenatal women

BACKGROUND

Although recommendations on folic acid use were issued by health authorities in a number of countries in the early 1990s, uptake of peri-conceptional folic acid is still disappointingly low. Regardless of food fortification policies, folic acid promotion will probably be required in most countries to optimize folate levels among women of child-bearing age. The aim of this study was to examine folic acid knowledge and use, and their determinants among antenatal women in the east of Ireland in 1997.

METHODS

Three hundred antenatal women attending their initial booking appointment in three Dublin maternity hospitals were surveyed. An interviewer-administered questionnaire was used with questions on folic acid knowledge and use, and demographic and obstetric questions. A univariate analysis of data was undertaken followed by a multivariate analysis using logistic regression to determine factors predicting knowledge and use of folic acid.

RESULTS

Seventy-six per cent of respondents had heard of folic acid, 16 per cent had taken it before pregnancy and 51 per cent during pregnancy. Women who had planned their pregnancy, were married and were relatively affluent were significantly more likely to have heard of folic acid, to know that it could prevent neural tube defects and to have taken it peri-conceptionally. Less affluent women tended to use their general practitioner (GP) more as a source of information and advice than those who were better off. In multivariate analysis, marriage and planned pregnancy were important predictors of folic acid knowledge whereas planned pregnancy advice given before pregnancy and relative affluence were predictive of peri-conceptional use.

CONCLUSIONS

Many women know of folic acid but do not take it peri-conceptionally. Women may associate folic acid with pregnancy and less with pre-pregnancy. Greater emphasis on peri-conceptional use should improve folic acid uptake. Focusing on less affluent women for folic acid promotion by GPs and other primary care professionals is also important.

Folic acid knowledge and use among expectant mothers in 1997: a comparison with 1996

This study examined changes in folic acid knowledge and use among antenatal women in Dublin maternity hospitals between 1996 and 1997, following a campaign to improve the very low uptake of peri-conceptional folic acid. The results showed significant improvements between the two years. Almost 76% of respondents had heard of folic acid in 1997 compared with 54% in 1996 (p < 0.01), with a shift in the proportion of people hearing of folic acid from hospital doctors to general practitioners (GP). Almost 43% of respondents in 1997 knew that folic acid can prevent spina bifida compared with 21% in 1996 (p < 0.01). A higher proportion was taking folic acid prior to conception in 1997 (16% vs 6%, p < 0.01). We conclude that the improvements may have been in part due to the promotional campaign among health professionals, women's groups and the media. However, less than a fifth of women were taking folic acid peri-conceptionally in 1997 and there is still scope for much improvement.

Knowledge and use of peri-conceptional folic acid among antenatal patients

Peri-conceptional folic acid can prevent more than half of all neural tube defects (NTDs). A cross-sectional interviewer administered study was undertaken among 300 women attending their first antenatal appointment in the three major Dublin maternity hospitals. The aim of the study was to monitor knowledge and behaviour with respect to peri-conceptional folic acid among antenatal patients. There was a 98% (295/300) response rate. 53.6% (158/295) had heard of folic acid. Such knowledge was significantly associated with age over 30 years (p < 0.001), a planned pregnancy (p < 0.001) and being married (p < 0.001). The majority (58.2%) found out about folic acid from lay sources such as friends or the media. One eighth (12.9%, 38/295) had been advised to take folic acid before pregnancy, the majority (58.3%, 21/38) having been advised by doctors. 21% (62/295) knew that it prevented spina bifida. 5.8% (17/295) had taken it before becoming pregnant. Taking folic acid before pregnancy was significantly associated with having a planned pregnancy (p < 0.005) and being married (p < 0.005). This study highlights the poor impact of health promotion campaigns to date and provides a challenge to health professionals.

National survey of MRSA: Ireland, 1995

The objective of this survey was to obtain an indication of the size of the methicillin-resistant Staphylococcus aureus (MRSA) problem in Ireland prior to introducing national MRSA control guidelines. A survey of all microbiology laboratories in Ireland was carried out over two weeks in Spring 1995. For patients from whom MRSA was isolated during the study period standard demographic and clinical data were requested and period prevalence/1000 discharges was calculated. All 45 microbiology laboratories surveyed responded. MRSA was isolated from 448 patients during the two-week period. The period prevalence of MRSA was 16.5/1000 discharges. Males aged > or = 65 had the highest rate (50/1000 discharges). Half of all isolates were from patients in surgical or medical wards, but 4% were from community-based sources such as GPs, nursing homes and hospices. Thirty-two percent of MRSA patients were infected rather than colonized. MRSA is clearly a significant problem in Ireland. While it is largely a hospital problem at present, the increasing trend towards day procedures and shorter hospital stay means that infection will increase in the community.

Carers of the elderly--knowledge, use of and satisfaction with day care services

This is a descriptive study of carers of dependent elderly in inner city Dublin, outlining their awareness, use of and satisfaction with day services. A striking finding from this work, consistent with other studies, is the heavy burden of care which is shouldered by informal carers which should be acknowledged by society. The study highlights a) that levels of use of domiciliary care by carers appear to be very low, b) that there is some evidence of targeting of domiciliary services to the more dependent elderly, c) that day centres and clubs are popular and acceptable to a minority of carers, d) that many carers have no informal help, e) where informal help is available, relatives of carers play a very important role in facilitating carers to accept formal domiciliary care. Recommendations include, a) improving the level and range of provision of domiciliary care, b) alerting professionals such as general practitioners and public health nurses to their role as informant and facilitator of formal care to carers, c) formulating a plan to encourage uptake of domiciliary services by carers, d) review of care provided in day centres.

Influences on breast feeding initiation and duration

The study objectives were to establish the prevalence of breast feeding at birth, at four and twelve weeks after birth and describe the factors associated with its initiation and duration. The study population consisted of all babies born in May 1993 (n = 162) to mothers resident in Kildare. The response rate was 145/162 (89 percent). Mothers were visited within fourteen days of the birth. Breast feeding mothers were re-visited when the baby was four to six weeks old and at twelve to fourteen weeks. Interviews were conducted using an interviewer administered questionnaire. Fifty-five mothers (38%) chose to breast feed at birth. Twelve (8%) had stopped by the first, ten (7%) by the second and fourteen (10%) by the third visit. Higher social class and maternal grandmother having breast fed were significantly associated with initiation (p < 0.05 and p < 0.0005 respectively). Smokers and non-working mothers were significantly less likely to breast feed and smokers had a significantly shorter duration of breast feeding but these associations disappeared on social class adjustment.

Plasmacyte-reticulum cell satellitism in multiple myeloma associated with amyloidosis

A novel morphological feature is described in a patient with myeloma and associated amyloidosis: characteristic clustering (satellitism) of neoplastic plasma cells around macrophages in bone marrow aspirates. Although described in myeloma cell culture, as far as is known, this is the first description of this phenomenon in a patient. This unique association may partly explain the origin of amyloid deposition in tissues and organs.

Identification, synthesis and immunogenicity of cuticular collagens from the filarial nematodes Brugia malayi and Brugia pahangi

The major structural proteins of the cuticle of the filarial nematode parasites Brugia malayi and Brugia pahangi were identified by extrinsic iodination and sensitivity to clostridial collagenase. At least 16 acidic components were identified in adult worms by 2-dimensional electrophoresis, with molecular weights ranging from 35,000 to 160,000. These proteins appear to be cross-linked by disulphide bonds, and localised in the basal and inner cortical layers of the cuticle. The outer cortex, containing the epicuticle, is insoluble in 1% sodium dodecyl sulphate and 5% 2-mercaptoethanol, and can be isolated free of cellular material. Despite their inaccessibility to the immune system in intact worms, antibodies to the cuticular collagens are provoked in humans infected with a variety of filarial parasites. Immunological cross-reactivity was demonstrated between a 35 kDa component and human type IV (basement membrane) collagen. Autoantibodies to type IV collagen were detected in a number of individuals with lymphatic filariasis, although no correlation could be drawn with observed pathology. Synthesis of cuticular collagens is discontinuous, occurs at negligible levels in mature adult male worms, and does not appear to involve the production of small molecular weight precursors, in contrast to Caenorhabditis elegans. Hybridisation with a heterologous cDNA probe coding for the alpha 2 chain of chicken type 1 collagen suggests that they are encoded by a multigene family.

Leishmania donovani metacyclic promastigotes: transformation in vitro, lectin agglutination, complement resistance, and infectivity

Freshly transformed Leishmania donovani amastigotes from hamster spleen were used to establish axenic cultures at high density in a modified Grace's medium, which was only partly replenished when cultures were fed. Small, free-swimming, highly active stationary phase promastigotes with a short cell body and long flagellum were induced in this medium. The freshly transformed stationary phase promastigotes so induced were less able to bind peanut agglutinin, had more than 40-fold increased resistance to killing by normal human serum, and 15-fold increased infectivity both in vivo and in vitro when compared to freshly transformed logarithmic phase or long term culture promastigotes. These short form promastigotes may correspond to the metacyclic promastigote forms in the sand fly vector.

Inflammatory responses to parasites

The patients we are concerned about in tropical medicine are unfortunately affected by a wide range of conditions, not only those seen and studied extensively in the West, such as cancer, cardiovascular diseases and viral or bacterial infections, but also the major protozoan and metazoan conditions – the parasitic diseases. It is with this spectrum of pathophysiological changes that occurs in this last group that we are presently concerned and this communication is intended to present an overview of the subject.

Macrophage type 3 complement receptors mediate serum-independent binding of Leishmania donovani. Detection of macrophage-derived complement on the parasite surface by immunoelectron microscopy

In this study, direct visual evidence for local opsonization of L. donovani by macrophage (M phi)-derived complement components was obtained using immunoelectron microscopy. C3 deposition was detected on the surface of both promastigotes and amastigotes after 20 min serum-free incubation with murine resident peritoneal M phi (RPM), followed by fixation and incubation first with specific antibody directed against C3 and then with gold-labelled protein A. Gold deposition was not observed around either form of the parasite if the anti-C3 antibody was omitted. For promastigotes, the degree of C3 deposition under serum-free conditions was comparable with that observed in the presence of an exogenous (serum) source of C3, but did not result in the same severe damage to the parasite as did the latter. Addition of sodium salicyl hydroxamate, which prevents covalent binding of C3 to activator surfaces, abrogated promastigote binding. Hence, although the anti-C3 antibody did not distinguish between native C3 and its breakdown product iC3b, these data support our earlier conclusion that promastigote binding to the CR3 of murine RPM is complement dependent. For amastigotes, gold deposition and binding to murine RPM were not eliminated by sodium salicyl hydroxamate. The presence of normal mouse serum resulted in increased gold deposition, but did not mediate either enhanced binding to M phi or damage to the amastigote. These data suggest that a proportion of C3 binding to the amastigote surface may be via noncovalent linkages, and that the C3 bound may not be in the correct form to mediate binding to CR3.

Oxygen radical release by adherent cell populations during the initial stages of a lethal rodent malarial infection

A series of experiments was carried out to assess the levels of reactive oxygen intermediates (ROI) released by macrophages and monocytes during an acute malarial infection, and to consider the importance of oxidant-induced parasite killing in host protection. Adherent cell populations were removed from the peritoneum and spleen of BALB/c and B10/D2/n mice between Days 0-5 of a Plasmodium yoelii nigeriensis infection. These cell populations were quantified, characterized and their ROI-releasing capacity was measured by following ferricytochrome c reduction upon stimulation with phorbol myristate acetate (PMA). Both strains of mice displayed higher numbers of macrophages and macrophage precursors as the infection progressed; this rise was more marked and accompanied by splenomegaly in BALB/c mice. A concurrent decrease in peritoneal cell numbers was observed. Splenic adherent cell populations released much lower levels of ROI than peritoneal macrophages upon triggering. The levels of ROI released from BALB/c splenic adherent cells rose gradually until Day 3, when the parasitaemia was slightly decreased. In contrast, splenic populations from B10 mice had a decreased capacity to release ROI, particularly after Day 3, when the parasitaemia rose sharply. In further studies, electron microscopy was used to detect H2O2 release during the in vitro interaction of peritoneal macrophages and parasitized erythrocytes. Cerium chloride staining techniques demonstrated that H2O production was not dependent on phagocytosis or the presence of immune serum, although levels were increased by the presence of the latter.

Biochemical surface components of Brugia pahangi microfilariae

The sheath and cuticle of microfilariae of Brugia pahangi were examined by electron microscopy and the presence of various proteins, carbohydrate and enzymes sought. The epicuticle of microfilariae consists of a pentalaminate structure (24.0 +/- 1.4 nm), a cortex (13.7 +/- 3.6 nm) and a basal zone (27.8 +/- 4.8 nm) which is often banded in appearance. The pentalaminate layers are not continuous at the base of the interannular grooves. The sheath and the epicuticle of B. pahangi stained positively with concanavalin A and saccharated iron oxide. The sheath of approximately 50% of microfilariae showed activity for acid phosphatase, 5' nucleotidase and peroxidase, but not for ATPases, alkaline phosphatase or esterase. No enzymes were detected in the epicuticle although the cortex and basal layers of the cuticle did show enzymic activity. Structures beneath the cuticle in the main body of the worms contained considerable enzymic activity. Microfilariae directly isolated from the blood of infected cats were found by immunochemical means to carry serum proteins on their sheaths but not on their cuticles. These studies extend the definition of the outer structures of microfilariae and confirm that they significantly differ in morphology and enzyme content from typical mammalian cell membranes.

Isolated adrenal cortex cells: hypersensitivity to adrenocorticotropic hormone after hypophysectomy

Cells from the adrenals of hypophysectomized rats (up to 28 days after operation) require less adrenocorticotropic hormone to induce one-half maximal rate of production of 3',5'-adenosine monophosphate than do cells from the adrenals of intact rats. A corresponding increase in sensitivity is reflected in the steroidogenic response to adrenocorticotropic hormone up to 2 days after hypophysectomy.