Modelling hospital disinfectant against multi-drug-resistant dry surface biofilms grown under artificial human sweat

BACKGROUND

Dry surface biofilms (DSBs) have been found abundantly across hospital surfaces within intensive care units and may explain how nosocomial pathogens can remain virulent and persist on surfaces for extended periods. Testing standards governing the performance of disinfectant products employ planktonic models under routine growth conditions, which are known to be less tolerant than their biofilm counterpart.

AIM

To evaluate biofilm models cultured under artificial human sweat (AHS), a source of nutrient expected on touch surfaces, to assess the antimicrobial performance of common cleaning agents, including a quaternary ammonium, hydrogen peroxide and active chlorine.

METHODS

Five single-species biofilms, using pathogenic bacteria such as Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis, were generated on stainless-steel substrates using a sedimentation protocol under both AHS and nutrient-rich conditions for a direct comparison of phenotypic tolerance. The biofilm models were grown over five days followed by desiccation cycles, before being submerged into the disinfectant solutions for up to 25 min. Epifluorescence (EF) microscopy using LIVE/DEAD™ stain was used to visualize microcolony viability.

FINDINGS

The results revealed biofilms cultured under AHS exhibited a greater antimicrobial tolerance and reduced speed of kill for all cleaning agents compared with the routine media; an average reduction of 72.4% vs 96.9%, respectively. EF microscopy revealed traces of viable bacteria across all coupons after disinfection indicating a potential opportunity for regrowth and recontamination.

CONCLUSION

The notable difference in biocidal performance between the two growth conditions highlights potential pitfalls within current antimicrobial test standards, and the importance of accurate representation of the microbial challenge.

An automated contact model for transmission of dry surface biofilms of Acinetobacter baumannii in healthcare

BACKGROUND

Dry surface biofilms (DSBs) have been recognized across environmental and equipment surfaces in hospitals and could explain how microbial contamination can survive for an extended period and may play a key role in the transmission of hospital-acquired infections. Despite little being known on how they form and proliferate in clinical settings, DSB models for disinfectant efficacy testing exist.

AIM

In this study we develop a novel biofilm model to represent formation within hospitals, by emulating patient to surface interactions.

METHODS

The model generates a DSB through the transmission of artificial human sweat (AHS) and clinically relevant pathogens using a synthetic thumb capable of emulating human contact. The DNA, glycoconjugates and protein composition of the model biofilm, along with structural features of the micro-colonies was determined using fluorescent stains visualized by epifluorescence microscopy and compared with published clinical data.

RESULTS

Micrographs revealed the heterogeneity of the biofilm across the surface; and reveal protein as the principal component within the matrix, followed by glycoconjugates and DNA. The model repeatably transferred trace amounts of micro-organisms and AHS, every 5 min for up to 120 h on to stainless-steel coupons to generate a biofilm model averaging 1.16 × 103 cfu/cm2 falling within the reported range for clinical DSB (4.20 × 102 to 1.60 × 107 bacteria/cm2).

CONCLUSION

Our in vitro DSB model exhibits many phenotypical characteristics and traits to those reported in situ. The model highlights key features often overlooked and the potential for downstream applications such as antibiofilm claims using more realistic microbial challenges.

Evaluating the environmental microbiota across four National Health Service hospitals within England

Hospital surfaces contaminated with microbial soiling, such as dry surface biofilms (DSBs), can act as a reservoir for pathogenic micro-organisms, and inhibit their detection and removal during routine cleaning. Studies have recognized that such increases in bioburden can hinder the impact of disinfectants and mask the detection of potential pathogens. Cleanliness within healthcare settings is often determined through routine culture-based analysis, whereby surfaces that exhibit >2.5 colony-forming units (CFU) per cm² pose a risk to patient health; therefore, any underestimation could have detrimental effects. This study quantified microbial growth on high-touch surfaces in four hospitals in England over 19 months. This was achieved using environmental swabs to sample a variety of surfaces within close proximity of the patient, and plating these on to non-specific low nutrient detection agar. The presence of DSBs on surfaces physically removed from the environment was confirmed using real-time imaging through episcopic differential interference contrast microscopy combined with epifluorescence. Approximately two-thirds of surfaces tested exceeded the limit for cleanliness (median 2230 CFU/cm²), whilst 83% of surfaces imaged with BacLight LIVE/DEAD staining confirmed traces of biofilm. Differences in infection control methods, such as choice of surface disinfectants and cleaning personnel, were not reflected in the microbial variation observed and resulting risk to patients. This highlights a potential limitation in the effectiveness of the current standards for all hospital cleaning, and further development using representative clinical data is required to overcome this limitation.

The Varietal Influence of Flavour Precursors from Grape Marc on Monoterpene and C13-Norisoprenoid Profiles in Wine as Determined by Membrane-Assisted Solvent Extraction (MASE) GC-MS

The winemaking by-product grape marc (syn. pomace) contains significant quantities of latent flavour in the form of flavour precursors which can be extracted and used to modulate the volatile composition of wine via chemical hydrolysis. Varietal differences in grapes are widely known with respect to their monoterpene content, and this work aimed to extend this knowledge into differences due to cultivar in volatiles derived from marc precursors following wine-like storage conditions. Marc extracts were produced from floral and non-floral grape lots on a laboratory-scale and from Muscat Gordo Blanco marc on a winery -scale, added to a base white wine for storage over five to six months, before being assessed using a newly developed membrane-assisted solvent extraction gas chromatography-mass spectrometry (GC-MS) method. The geraniol glucoside content of the marc extracts was higher than that of juices produced from each grape lot. In all wines with added marc extract from a floral variety, geraniol glucoside concentration increased by around 150–200%, with increases also observed for non-floral varieties. The relative volatile profile from extracts of the floral varieties was similar but had varied absolute concentrations. In summary, while varietally pure extracts would provide the greatest control over flavour outcomes when used in winemaking, aggregated marc parcels from floral cultivars may provide a mechanism to simplify the production logistics of latent flavour extracts for use in the wine sector.

A review of treatment options for behavioural manifestations of clinical anxiety as a comorbidity in dogs with idiopathic epilepsy

Psychiatric comorbidities affect a large percentage of people with epilepsy and have a detrimental impact on their quality of life. Recently, behavioural comorbidities, with similar characteristics to human psychiatric diseases, have been identified in dogs with idiopathic epilepsy. In particular, behaviours motivated by the fear-anxiety emotional system have been found to be associated with the occurrence of idiopathic epilepsy in both dogs receiving anti-epileptic drugs, and drug-naïve dogs. There has been little research into the relationship between epilepsy and behavioural signs, and even less into potential treatment protocols. The following article will review available literature from human medicine to describe the current state of knowledge about the bi-directional relationship between anxiety and epilepsy, draw parallels from reported anxiogenic and anxiolytic properties of anti-epileptic drugs and attempt to provide pharmaceutical and behavioural guidance for veterinary patients with epilepsy and comorbid anxiety.

Evaluating different concentrations of hydrogen peroxide in an automated room disinfection system

A comparative study was made on the efficacy of 5, 10 and 35% weight by weight (w/w) hydrogen peroxide solutions when applied using an automated room disinfection system. Six-log biological indicators of methicillin-resistant Staphylococcus aureus (MRSA) and Geobacillus stearothermophilus were produced on stainless steel coupons and placed within a large, sealed, environmentally controlled enclosure. Five percent hydrogen peroxide was distributed throughout the enclosure using a Bioquell hydrogen peroxide vapour generator (BQ-50) for 40 min and left to reside for a further 200 min. Biological indicators were removed at 10-min intervals throughout the first 120 min of the process. The experiment was repeated for 10 and 35% hydrogen peroxide solutions. Five percent and 10% hydrogen peroxide solutions failed to achieve any reduction of MRSA, but achieved full kill of G. stearothermophilus spores at 70 and 40 min respectively. Thirty-five percent hydrogen peroxide achieved a 6-log reduction of MRSA after 30 min and full kill of G. stearothermophilus at 20 min. The concentration of 5% hydrogen peroxide within the enclosure after the 200-min dwell was measured at 9·0 ppm. This level exceeds the 15-min Short Term Exposure Limit (STEL) for hydrogen peroxide of 2·0 ppm. Users of automated hydrogen peroxide disinfection systems should review system efficacy and room re-entry protocols in light of these results.

SIGNIFICANCE AND IMPACT OF THE STUDY

This research allows hospital infection control teams to consider the impact and risks of using low concentrations of hydrogen peroxide for disinfection within their facilities, and to question automated room disinfection system providers on the efficacy claims they make. The evidence that low concentration hydrogen peroxide solutions do not rapidly, autonomously break down, is in contradiction to the claims made by some hydrogen peroxide equipment providers and raises serious health and safety concerns. Facilities using hydrogen peroxide systems that claim autonomous break down of hydrogen peroxide should introduce monitoring procedures to ensure rooms are safe for re-entry and patient occupation.

Combination of GM-CSF and cytosine in myelodysplasia results in improved neutrophil function

Granulocyte-macrophage colony-stimulating factor (GM-CSF) was given concurrently with low-dose cytosine arabinoside for 3 weeks to patients with myelodysplasia. Neutrophil activation as evidenced by increased chemiluminescence and reduced surface expression of CD16 was consistently seen during therapy. An attendant fall in chemotaxis was also observed. These effects occurred even when neutrophil counts did not rise significantly at lower doses of GM-CSF. Although no improvement in anaemia or thrombocytopenia was observed, the neutrophil counts became normal during therapy without significant expansion of marrow cellularity or colony-forming ability. No major toxicities were observed, even at higher dosages of GM-CSF.

Three centuries of stomach symptoms in Scotland

BACKGROUND

Stomach pain and discomfort have been reported since antiquity.

AIM

To follow the time trends since the 18th century of dyspepsia, gastric ulcer, duodenal ulcer, and benign oesophageal disease to test when dyspepsia started to become a major clinical problem.

METHODS

The annual in- and out-patient records of the last three centuries from the Scottish Royal Infirmaries of Edinburgh, Aberdeen, Glasgow and Dundee were analysed. In addition, dispensary attendances, clinicians' casebooks, students' notebooks and medical texts have been scrutinized for historic statistics of upper gastrointestinal disease.

RESULTS

Dyspepsia was first recorded in the 1750s and increased markedly subsequently. Such dyspepsia persisted after gastric and duodenal ulcers appeared in the late 19th century and then declined again in the late 20th century. Non-ulcer dyspepsia has remained the commonest diagnosis made after endoscopy for stomach pain in the beginning of the 21st century.

CONCLUSION

The current commonest diagnosis of stomach pain, dyspepsia dates from the mid-18th century. Any explanations of its causation need to consider this timing.

Why do women decline prenatal screening and diagnosis? Australian women's perspective

In this paper, we examine reasons for declining both prenatal screening, and diagnosis among a small group of pregnant women in Victoria, Australia. Semi-structured questionnaires were used to elicit women's account of their refusals of offers during pregnancy. Previous literature suggests that women decline prenatal screening and diagnosis because they are against abortion and the medicalisation of pregnancy, and have conoerns about the health and well-being of their fetuses. Women in this study had similar reasons but they also had other reasons for declining. Most clearly was that related to 'risk' brought about by the prospect of knowledge gained from undertaking prenatal screening and diagnostic tests, which would cause emotional distress and lead to further difficult decisions. The results have implications for the development and expansion of prenatal screening and diagnosis for pregnant women in Australia and elsewhere. We are not suggesting that prenatal screening and diagnosis is a problem for all women or even most women. However, health service providers must provide information about prenatal screening and diagnosis that is appropriate for all pregnant women, presenting all options, including that of not having any screening or diagnostic test. In doing so we will be facilitating the opportunity for women to make an informed choice and acknowledging the existence and importance of this small, but concerned group of women.

Transcriptional activation of the rat vesicular monoamine transporter 2 promoter in gastric epithelial cells: regulation by gastrin

Vesicular monoamine transporter 2 is important for the accumulation of monoamine neurotransmitters into synaptic vesicles and histamine transport into secretory vesicles of the enterochromaffin-like cell of the gastric corpus. In this study we have investigated the mechanisms regulating the transcriptional activation of the rat vesicular monoamine transporter 2 (VMAT2) promoter in gastric epithelial cells. Maintenance of basal levels of transcription was dependent on the presence of SP1, cAMP-response element (CRE), and overlapping AP2/SP1 consensus sequences within the region of promoter from -86 to +1 base pairs (bp). Gastrin stimulation increased transcriptional activity, and responsiveness was shown to be dependent on the CRE (-33 to -26 bp) and AP2/SP1 (-61 to -48 bp) consensus sites but independent of the SP1 site at -86 to -81 bp. Gastrin-induced transcription was dependent on the cooperative interaction of an uncharacterized nuclear factor of approximately 23.3 kDa that bound to the putative AP2/SP1 site, CRE-binding protein (CREB), and CREB-binding protein/p300. Gastrin stimulation resulted in the increased binding of phosphorylated CREB to the promoter, but it did not result in the increased binding of the AP2/SP1-binding protein. The gastrin responsiveness of the promoter was shown to be dependent on both the protein kinase C and mitogen-activated protein kinase/extracellular signal-regulated kinase kinase-signaling pathways, which may converge on the AP2/SP1-binding protein.

Seasonality of eating pathology on the eating attitudes test in a nonclinical population

OBJECTIVE

To determine whether there are seasonal fluctuations in eating pathology in a nonclinical population.

METHOD

The Eating Attitudes Test (EAT) was completed by 322 subjects during winter and again during summer. Summer and winter responses were compared to investigate differences in EAT total and subscale scores and for individual EAT items. Numbers of subjects fluctuating across the seasons by more than 2 SDs of the cohort's scores were identified.

RESULTS

The cohort showed no significant seasonal change on EAT-40 totals, EAT-26 totals, or within the EAT subscales. There were significant (p <.025) seasonal fluctuations on four of the EAT-40 questions. For individual respondents, there was no greater likelihood of scoring significantly higher in the winter than in the summer.

DISCUSSION

Clinically significant seasonal fluctuations in eating pathology on the EAT did not occur in this nonclinical population. It is debatable whether items within the EAT which show significant seasonal fluctuations should be retained or discarded.

Transcriptional activation of vesicular monoamine transporter 2 in the pre-B cell line Ea3.123

Uptake and storage of monoamines in secretory granules is accomplished by vesicular monoamine transporters, and it is likely that vesicular monoamine transporter 2 (VMAT2) is important for histamine transport in vivo. In the present study we have used the pre-B-cell line Ea3.123 to investigate the mechanisms involved in the transcriptional activation of the VMAT2 gene. In Ea3.123 cells, VMAT2 mRNA abundance was increased following mobilization of intracellular calcium, and this increased mRNA expression was paralleled by changes in l-histidine decarboxylase mRNA, suggesting that VMAT2 may be responsible for sequestration of histamine into secretory vesicles in this cell line. We cloned the 5'-flanking region of the VMAT2 gene and determined its transcriptional start site by primer extension of rat VMAT2 mRNA. There was no TATA or TATA-like sequence upstream of this region; instead there were GC-rich elements, Ca2+/cAMP-response-element- and SP1-binding motifs. Approx. 900 bp upstream of the transcriptional start site was a purine-pyrimidine repeat sequence that may form a Z-DNA structure. A series of 5'-deletional VMAT2-promoter segments cloned upstream of a luciferase reporter were capable of driving transcription and indicated the presence of multiple regulatory elements, while stimulation with ionomycin or PMA resulted in an increased level of the transcriptional activity of the 5'-promoter segments studied.

Stimulation of primed neutrophils by soluble immune complexes: priming leads to enhanced intracellular Ca2+ elevations, activation of phospholipase D, and activation of the NADPH oxidase

Soluble immune complexes activate a rapid burst of reactive oxidant secretion from neutrophils that have previously been primed with GM-CSF. Binding of these complexes to the cell surface of unprimed neutrophils results in the generation of intracellular Ca2+ transients, but the NADPH oxidase fails to become activated. No phospholipase D activity was observed following the addition of soluble immune complexes to unprimed cells. Upon priming with GM-CSF, the intracellular Ca2+ signal generated following soluble complex binding was greatly extended and phospholipase D was activated: there was also increased phosphorylation of proteins on tyrosine residues and the NADPH oxidase was activated. When Ca2+ influx was prevented, this phospholipase D activity was not observed. This primed oxidase activity was completely inhibited by erbstatin. Treatment of unprimed neutrophils with pervanadate (to inhibit protein tyrosine phosphatases) mimicked the effects of priming in that pervanadate-treated neutrophils secreted reactive oxidants in response to soluble immune complexes. The data indicate that during priming a new signaling pathway is activated that involves Ca2+ influx, phosphorylation on tyrosine residues, phospholipase D activity, and NADPH oxidase activation.

Activation of human neutrophils by soluble immune complexes: role of Fc gamma RII and Fc gamma RIIIb in stimulation of the respiratory burst and elevation of intracellular Ca2+

Activation of control, unprimed neutrophils with soluble immune complexes fails to generate a respiratory burst. However, if the cells are primed with either tumor necrosis factor-alpha or granulocyte-macrophage colony-stimulating factor prior to addition of soluble immune complexes, then a rapid and transient burst of reactive oxidant secretion is observed. In unprimed neutrophils the soluble immune complexes stimulate an intracellular Ca2+ transient that arises from the mobilization of intracellular Ca2+. However, in primed cells, an "extra" intracellular Ca2+ signal is observed that arises from Ca2+ influx. After removal of Fc gamma RIIIb by treatment with pronase or PI-PLC, the soluble immune complexes fail to activate a respiratory burst in unprimed neutrophils and the "extra" Ca2+ signal is not observed. These results indicate that during priming Fc gamma RIIIb becomes functionally activated and thence its ligation leads to stimulated Ca2+ influx and the generation of intracellular signals that lead to NADPH oxidase activation. Experiments using Fab/F(ab')2 fragments to specifically crosslink either Fc gamma RII or Fc gamma RIIIb and experiments with neutrophils from an individual with Fc gamma RIIIb gene deficiency confirm this important function for Fc gamma RIIIb in neutrophil activation.

Stimulation of intracellular Ca2+ levels in human neutrophils by soluble immune complexes. Functional activation of FcgammaRIIIb during priming

Soluble immune complexes bind to unprimed neutrophils and generate intracellular Ca2+ transients but fail to activate the NADPH oxidase. Following priming of the neutrophils with either tumor necrosis factor alpha or granulocyte-macrophage colony-stimulating factor, stimulation of the cells with the soluble immune complexes leads to an enhanced Ca2+ signal and significant secretion of reactive oxidants. The enhanced Ca2+ signal observed in primed neutrophils results from the influx of Ca2+ from the external environment and is partly sensitive to tyrosine kinase inhibitors. This is in contrast to the Ca2+ signal observed in unprimed neutrophils, which arises from the mobilization of intracellular stores. When the surface expression of FcgammaRIIIb on primed neutrophils was decreased either through incubation with Pronase or phosphoinositide-specific phospholipase C, the extra enhanced Ca2+ mobilization seen in primed cells was significantly lowered, while the initial rise in intracellular Ca2+ was unaffected. Depletion of FcgammaRIIIb had no significant effect on the Ca2+ transients in unprimed neutrophils. Cross-linking FcgammaRII, but not FcgammaRIIIb, induced increases in intracellular Ca2+ in unprimed neutrophils, while cross-linking either of these receptors increased Ca2+ levels in primed neutrophils. The FcgammaRII-dependent intracellular Ca2+ rise in primed cells was unaffected by incubation in Ca2+-free medium, whereas the FcgammaRIIIb-dependent transient was significantly decreased when Ca2+ influx was prevented in Ca2+-free medium supplemented with EGTA. Cross-linking either FcgammaRII or FcgammaRIIIb in primed or unprimed cells failed to stimulate substantial levels of inositol 1,4,5-trisphosphate production. These results indicate that following stimulation of primed neutrophils with soluble immune complexes the enhanced Ca2+ mobilization observed is the result of a functional activation of the glycosylphosphatidylinositol-linked FcgammaRIIIb.

Neutrophils from the synovial fluid of patients with rheumatoid arthritis express the high affinity immunoglobulin G receptor, Fc gamma RI (CD64): role of immune complexes and cytokines in induction of receptor expression

Neutrophils isolated from the synovial fluid of 16/24 patients with rheumatoid arthritis expressed Fc gamma RI (CD64), the high-affinity receptor for monomeric immunoglobulin G (IgG), on their cell surface. Receptor expression ranged from 17% to 168% of the level of expression obtained after incubation of control blood neutrophils with 100 U/ml interferon-gamma (IFN-gamma) for 24 hr in vitro. Similarly, mRNA for Fc gamma RI was detected in synovial fluid neutrophils from 12/15 patients and transcript levels ranged from 5% to 200% of the values obtained after treatment of blood neutrophils with IFN-gamma for 4 hr in vitro. No surface expression nor mRNA were detected in freshly isolated blood neutrophils from either patients or from healthy controls. Addition of cell-free synovial fluid to control blood neutrophils induced both mRNA and surface expression of Fc gamma RI to levels that were comparable to those achieved after addition of IFN-gamma. Neither soluble nor insoluble immune complexes appeared to be involved in induction of Fc gamma RI expression in spite of the ability of these complexes to induce protein biosynthesis. Synovial fluid-induced expression of Fc gamma RI was partially blocked by incubation with neutralizing IFN-gamma antibodies, whilst neutralizing interleukin (IL)-6 antibodies had little effect. Levels of IFN-gamma measured within these synovial fluids ranged from 0 to 2.7 U/ml, well within the range known to induce neutrophil Fc gamma RI expression. These data thus indicate that gene expression in synovial fluid neutrophils is selectively activated as the cells enter the diseased joint. Furthermore, these data indicate that induced expression of Fc gamma RI may alter the ability of infiltrating neutrophils to respond to IgG-containing immune complexes present in these joints.

Regulated expression of GATA-6 transcription factor in gastric endocrine cells

BACKGROUND & AIMS

GATA transcription factors may regulate gene expression in developing tissues, including gut epithelium. In the stomach, their expression has been linked to regulation of proton pump genes. However, GATA consensus sequences also occur in the promoter of the histidine decarboxylase gene, located in enterochrommafin-like cells. The aim of this study was to determine if GATA factors are located in gastric endocrine cells and to examine their expression during development and in response to changes in the gastric luminal environment.

METHODS

Polymerase chain reaction cloning, Northern blot, and gel shift assays were used to examine GATA expression in gastric endocrine cells; changes in GATA messenger RNA during development and in response to fasting, feeding, and gastric achlorhydria were determined by Northern blot.

RESULTS

GATA-6 was expressed strongly in rodent gastric endocrine cell fractions, in a human ECL cell tumor, and in an endocrine cell line (STC-1) derived from gut epithelium; proteins from STC-1 cells bound specifically to GATA consensus sequences in the human histidine decarboxylase promoter. GATA messenger RNA abundance was up-regulated during terminal differentiation of the rat stomach and on feeding after a fast.

CONCLUSIONS

The GATA-6 transcription factor is expressed in gastric endocrine cells and is a potential regulator of gastric differentiation and of genes involved in the response to feeding.

Stimulation of primed neutrophils by soluble immune complexes

Soluble IgG-containing immune complexes are unable to initiate oxidant production in unprimed neutrophils. However, priming of the neutrophils with either granulocyte-macrophage colony-stimulating factor (GM-CSF) or cytochalasin B prior to exposure to these complexes results in activation of a rapid and extensive secretion of reactive oxidants. In this study, we have investigated the ability of soluble immune complexes to: (1) induce oxidant generation; (2) bind to the cell surface; and (3) induce Ca2+ transients in neutrophils primed by incubation with GM-CSF or cytochalasin B. Our findings give new insight into the molecular processes involved in the "priming" phenomenon.

Phospholipases Involved in Activation of the Neutrophil NADPH Oxidase

Stimulation of neutrophils with a variety of stimuli can result in the activation of phospholipases A2, C, or D with the resultant hydrolysis of plasma membrane phospholipids and the formation of important second messenger molecules. In the neutrophil, the activities of these phospholipases have been implicated in the processes of both stimulating and maintaining oxidase activation. In this review, some of the methods currently used to measure the products of phospholipase activation in the neutrophil are described, along with the possible role of their products in reactive oxidant production by the neutrophil NADPH oxidase.

Nutritional status and food security: winter nutrition monitoring in Sarajevo 1993-1994

OBJECTIVE

To monitor nutritional status and food security throughout the winter of 1993-1994 in order to provide early warning of any deterioration, identify the nutritionally vulnerable and so enable humanitarian agencies to respond appropriately.

DESIGN

Four different household groups were prospectively followed: residents, refugees in collective centres, refugees in private accommodation and elderly living alone (either residents or refugees). Four local communities were purposively selected and two collective centres were randomly selected. Households were randomly selected within each community and collective centre. An additional sample of all elderly inhabitants of the old people's home were nutritionally assessed only.

SETTING

Monitoring was implemented in the besieged city of Sarajevo.

SUBJECTS

143 households with 90 children (< 18 years), 230 adults (18-59 years), and 94 elderly (60 + years) members, and 40 elderly inhabitants of the old people's home were monitored.

INTERVENTIONS

Every month from December 1993 to March 1994, information on household food security was collected through structured questionnaires. All subjects were weighed and their heights measured. Weight for age Z scores in children (six months to 12 years) and body mass index (BMI) in adults and the elderly were calculated.

RESULTS

While the nutritional status of adults and children consistently remained normal, high levels of undernutrition were detected among the elderly ranging from 16% to 21% (BMI < 18.5). Between December 1993 and February 1994, adults lost an average of 260 grams in weight (paired t test p = 0.005). Indicators of household food security (food stocks per person, market food prices and access to food aid) showed negative trends during the same time period.

CONCLUSIONS

Whilst there was no nutritional disaster in Sarajevo over the winter 1993-1994, there were signs that capacity to cope was weakening in some groups. The elderly were identified as the most nutritionally vulnerable due to sickness, cold, stress and problems related to food preparation. The most food insecure group were refugees in collective centres who were highly dependent on food aid, were less likely to have relatives outside Sarajevo to support them, had fewer possessions to sell and were least likely to have gardens.

Who is nutritionally vulnerable in Bosnia-Hercegovina?

OBJECTIVE

To monitor nutritional status and food security in order to identify nutritionally vulnerable groups.

DESIGN

Members of five different household groups (urban and rural residents, displaced people in collective centres and private accommodation, elderly people living without younger family) and all residents of two old people's homes were prospectively followed. Households were selected from 20 local communities and nine collective centres.

SETTING

Monitoring carried out in three besieged areas of Bosnia-Hercegovina (Sarajevo, Tuzla, and Zenica).

SUBJECTS

1739 individuals sampled.

INTERVENTIONS

Data collected every month from December 1993 to May 1994. Information on household food security was collected through structured questionnaires. All subjects were weighed and their heights measured. Weight for age Z scores were calculated for children; body mass index was calculated for adults and elderly people.

RESULTS

From December 1993 to February 1994, before a temporary cease fire, access to food was reduced. In February 1994 no significant signs of undernutrition were detected among children or adults, but elderly people had higher than expected levels of undernutrition (15.5% with body mass index < 18.5), a higher rate of weight loss than adults (1.2 kg over two months), and a higher prevalence of self reported illness.

CONCLUSIONS

Elderly people in Bosnia-Hercegovina are at greater risk of undernutrition than other age groups. Undernutrition may be precipitated in elderly people by sickness, cold, stress, and problems related to food preparation. The health and welfare of elderly people during the emergency in Bosnia-Hercegovina require special attention, and integrated age care programmes are needed.

The impact of a reduced and uncertain food supply in three besieged cities of Bosnia-Hercegovina

Nutritional status and household food security were longitudinally monitored in three besieged cities of Bosnia-Hercegovina (Sarajevo, Zenica and Tuzla) during the winter and spring of 1993 to 1994. The objectives were to provide early warning of a deterioration in the food and nutrition situation and identify particularly vulnerable groups so that action could be taken to prevent potential undernutrition and target resources to the most needy. Before the cease-fire, which came into effect at the end of February 1994, trends in various indicators (weight loss, decline of household food stocks, rising food prices, reduction in food aid distribution, sale of possessions) suggested that the situation was deteriorating. Access to food improved as a result of the cease-fire, however, which was reflected in improvements in indicators of food security and weight gain. The impact of, and response to, the food emergency differed between individuals, households and locations; the elderly were found to be more nutritionally vulnerable than children or adults, households with the least access to resources were the most food insecure, while the city of Zenica appeared to be particularly hard hit. The findings show the effects of an uncertain and reduced food supply on a previously well-fed healthy population in an industrialised country. The value and constraints of an Early Warning System set up to monitor trends in an emergency in a European context are discussed.

Role of Fc gamma receptors in the activation of neutrophils by soluble and insoluble immunoglobulin aggregates isolated from the synovial fluid of patients with rheumatoid arthritis

OBJECTIVES

Synovial fluid from patients with rheumatoid arthritis contains both soluble and insoluble immunoglobulin aggregates which activate reactive oxidant production in human neutrophils. The objectives were to determine the roles played by Fc gamma receptors in activation of neutrophils by these complexes.

METHODS

Pronase treatment was used to remove Fc gamma RIII from the neutrophil surface and blocking monoclonal antibodies were used to prevent the binding of complexes to Fc gamma RII and Fc gamma RIII.

RESULTS

When Fc gamma RIII was removed from the cell surface by pronase treatment, activation by the soluble aggregates did not occur [mean (SD) inhibition 89 (16)%, n = 6] whereas activation via the insoluble aggregates was less affected [34 (16)%, n = 6]. Blocking the binding to Fc gamma RIII with antibodies decreased activation in response to the soluble aggregates [mean (SD) inhibition 71 (22)%, n = 8] but again had a lower effect on activation by the insoluble aggregates [40 (17)%, n = 9]. When binding to Fc gamma RII was blocked, activation via the soluble aggregates was substantially inhibited [mean (SD) 93 (13)%, n = 8] whereas that via the insoluble aggregates was inhibited to a much lesser extent [28 (38)%, n = 9]. When Fc gamma RII and III were simultaneously blocked, activation by the insoluble aggregates was only inhibited by 45% [(19), n = 5].

CONCLUSION

These data thus indicate that activation of human neutrophils by soluble immunoglobulin aggregates from rheumatoid synovial fluid occurs via cooperative occupancy of both Fc gamma RII and III: perturbation of binding to either of these receptor classes will abrogate activation.

Identification of a subgroup of myelodysplastic patients with a neutrophil stimulation-signalling defect

f-Met-Leu-Phe-stimulated luminol-enhanced chemiluminescence was found to be repeatedly defective in some MDS patients. This defect was not attributed to myeloperoxidase deficiency, nor to a defect in NADPH oxidase function, because PMA chemiluminescence was found to be normal in these individuals. An arbitrary value of 7 mV (half the mean control value) was chosen to subdivide the group: MDS patients with values < 7 mV had a mean f-Met-Leu-Phe chemiluminescence response of 2.5 +/- 0.5 compared to MDS patients with values > 7 mV who had a mean response of 15.6 +/- 1.6 mV, P < 0.01 (healthy controls 14 +/- 2 mV). The characteristics of the f-Met-Leu-Phe receptor and initial calcium flux results suggested that the receptor itself was normal in number and function in low f-Met-Leu-Phe responders. The rate of superoxide generation, which is calcium-dependent, was also found to be in the normal range in low f-Met-Leu-Phe responders, although total superoxide production was reduced in some of these patients. When MDS neutrophils with a low f-Met-Leu-Phe response were stimulated with PMA, chemiluminescence was normal, suggesting normal activity of the NADPH-oxidase complex. Furthermore, myeloperoxidase activity was reduced in only three out of the 11 low f-Met-Leu-Phe responders. Following priming with GM-CSF, f-Met-Leu-Phe chemiluminescence was 27 +/- 1.6 mV in low f-Met-Leu-Phe responders compared to controls (87.7 +/- 11 mV, P < 0.005). Thus, although responses were improved, they were not as marked as in control neutrophils. These data suggest that a subgroup of MDS patients have a low f-Met-Leu-Phe chemiluminescence response which is not due to a defect in the f-Met-Leu-Phe receptor or oxidase activity, and in the majority of cases MPO activity is normal. Initial patient survival data suggest that these patients may have an increased risk of infective mortality. It is proposed that defective f-Met-Leu-Phe chemiluminescence results from a putative defect in cell-signalling mechanism upstream of PKC, and GM-CSF priming only partially improves responsiveness.

Phospholipase D-dependent and -independent activation of the neutrophil NADPH oxidase

Stimulation of the respiratory burst of human neutrophils by fMet-Leu-Phe (in the absence of cytochalasin B) is largely unaffected when the activities of protein kinase C and phospholipase D are inhibited. This has been confirmed using three separate assays to measure the respiratory burst. However, whilst these enzymes are not required for the initiation or maximal rate of oxidant generation, they are required to sustain oxidase activity. In contrast, in the presence of cytochalasin B, fMet-Leu-Phe stimulated oxidase activity is much more dependent on phospholipase D activity. It is proposed that (in the absence of cytochalasin B) activation of the NADPH oxidase utilises cytochrome b molecules that are already present on the plasma membrane and activation occurs independently of phospholipase D and protein kinase C. Once these complexes are inactivated, then new cytochrome b molecules must be recruited from sub-cellular stores. This translocation and/or activation of these molecules is phospholipase D dependent. Some support for this model comes from the finding that the translocation of CD11b (which co-localises with cytochrome b) onto the cell surface is phospholipase D dependent.

Stimulation of reactive oxidant production in neutrophils by soluble and insoluble immune complexes occurs via different receptors/signal transduction systems

Cell-free synovial fluid from patients with rheumatoid arthritis contains soluble and insoluble IgG-containing immune complexes which activate reactive oxidant production in human neutrophils. In this report we have measured the effects of inhibitors of signal transduction pathways on neutrophil activation by these complexes and also following activation by synthetic soluble and insoluble immune complexes made from human serum albumin (HSA) and anti-(HSA) antibodies. In all aspects studied, the soluble rheumatoid complexes and the soluble synthetic complexes were indistinguishable in the ways in which they activated neutrophils. Activation of reactive oxidant production in response to these soluble complexes was completely inhibited by pertussis toxin (indicating G-protein coupling of receptor occupancy), completely insensitive to staurosporine (indicating that oxidant production did not require protein kinase C activity), only marginally (< 30%) inhibited by butanol (indicating that dependence upon activity of phospholipase D was minimal), and completely inhibited by chloracysine, an inhibitor of phospholipase A2. In contrast, activation of reactive oxidant production in response to the insoluble rheumatoid or insoluble synthetic immune complexes was largely pertussis toxin insensitive, inhibited by > 50% by staurosporine, inhibited by > 50% by butanol, and completely inhibited by chloracysine. These results show that the receptor-mediated signal transduction systems activated by the soluble and insoluble immune complexes are different. Because the soluble complexes activate a transient burst of reactive oxidant secretion from primed neutrophils, the mechanisms regulating either the release or the intracellular production of oxidants within rheumatoid joints are distinct and hence may be pharmacologically modified independently of each other.

Strong inhibition of fibrinogen binding to platelet receptor alpha IIb beta 3 by RGD sequences installed into a presentation scaffold

In order to probe the structural constraints on binding of RGD sequences to the platelet receptor alpha IIb beta 3 we have used recombinant DNA techniques to install the RGD sequence into 'presentation scaffolds', small proteins of known 3-D structure chosen to present guest sequences in constrained orientations. Using Escherichia coli expression systems we made sequence variants in which loop residues of the immunoglobulin VL domain REI and of human interleukin-1 beta were replaced (without changing polypeptide length) by the RGD sequence at positions predicted, based on small molecule studies, to orient the RGD moiety into an active conformation. These variants do not compete for fibrinogen binding to alpha IIb beta 3 up to almost 1 mM concentration. Unfolded or proteolytically fragmented forms of these same proteins do compete, however, showing that the RGD sequences in the mutants must be prohibited from binding by constraints imposed by scaffold structure. To suppress the effects of such structural constraints we constructed two sequence variants in which RGD-containing sequences 42-57 or 44-55 from the snake venom platelet antagonist kistrin were inserted (this increasing the length of the loop) into the third complementarity determining loop of REI. Both of these variants compete strongly for fibrinogen binding with IC50s in the nM range. These results, plus data on kistrin-related peptides also presented here, suggest that the molecular scaffold REI is capable of providing to an installed sequence a structural context and conformation beneficial to binding. The results also suggest that in order to bind well to alpha IIb beta 3, RGD sequences in protein ligands must either project significantly from the surface of the scaffold and/or retain a degree of conformational flexibility within the scaffold. Molecular scaffolds like REI should prove useful in the elucidation of structure-function relationships and the discovery of new active sequences, and may also serve as the basis for novel therapeutic agents.

Receptor expression in synovial fluid neutrophils from patients with rheumatoid arthritis

OBJECTIVES

The aim of this study was to determine if neutrophils isolated from the blood and synovial fluid of patients with rheumatoid arthritis had patterns of receptor expression resembling those of blood neutrophils from controls which had been activated and primed in vitro.

METHODS

Fluorescence activated cell sorting was used to measure receptor expression in paired blood and synovial fluid neutrophils from patients and in control neutrophils exposed to phorbol myristate acetate and granulocyte-macrophage colony stimulating factor.

RESULTS

There was no significant difference in the patterns of receptor expression in blood neutrophils from patients and healthy controls, but neutrophils in the synovial fluid had been primed and activated within the joint. About 50% of rheumatoid synovial fluid neutrophil samples expressed Fc gamma RI, a high affinity receptor for monomeric IgG, which is only expressed in neutrophils exposed to cytokines.

CONCLUSIONS

Synovial fluid neutrophils are activated and primed within the inflamed joint and hence their ability to respond to activating factors such as immune complexes will be modulated. As the expression of Fc gamma RI requires active biosynthesis, this work indicates that selective gene activation occurs when neutrophils are recruited into rheumatoid joints.

Activation of neutrophils by soluble and insoluble immunoglobulin aggregates from synovial fluid of patients with rheumatoid arthritis

OBJECTIVES

Previous work has shown that synovial fluid isolated from patients with active rheumatoid arthritis contains soluble (not sedimented by centrifugation at 11,600 g for two minutes) and insoluble (sedimented by centrifugation at 11,600 g for two minutes) immunoglobulin aggregates that are capable of activating reactive oxidant production by bloodstream neutrophils. The purpose of this study was to determine which of these types of immunoglobulin aggregates activated the secretion of reactive oxygen metabolites and granule enzymes from neutrophils.

METHODS

Cell free synovial fluid (from patients with rheumatoid arthritis) was added to neutrophils isolated from blood of healthy controls that had been incubated in the presence and absence of granulocyte-macrophage colony stimulating factor (GM-CSF). Reactive oxidant production was measured by luminol chemiluminescence (which detects both intracellular and extracellular oxidant production) and by cytochrome c reduction (which measures superoxide secretion).

RESULTS

The soluble aggregates only activated neutrophils that were previously primed, and activated a rapid and transient burst of reactive oxidant secretion. On the other hand, the insoluble aggregates activated primed and unprimed neutrophils with similar efficacy and most of the oxidants generated (especially in unprimed cells) were intracellular. The soluble aggregates, but not the insoluble aggregates, also activated the secretion of myeloperoxidase from neutrophils that had either been pretreated with cytochalasin B or primed with GM-CSF.

CONCLUSION

It is thus proposed that these soluble immunoglobulin aggregates are responsible for activation of the release of tissue damaging granule enzymes and reactive oxidants from primed neutrophils within the rheumatoid joint.

X-ray analyses of aspartic proteinases. V. Structure and refinement at 2.0 A resolution of the aspartic proteinase from Mucor pusillus

The structure of mucor pusillus pepsin (EC 3.4.23.6), the aspartic proteinase from Mucor pusillus, has been refined to a crystallographic R-factor of 16.2% at 2.0 A resolution. The positions of 2638 protein atoms, 221 solvent atoms and a sulphate ion have been determined with an estimated root-mean-square (r.m.s.) error of 0.15 to 0.20 A. In the final model, the r.m.s. deviation from ideality for bond distances is 0.022 A, and for angle distances it is 0.050 A. Comparison of the overall three-dimensional structure with other aspartic proteinases shows that mucor pusillus pepsin is as distant from the other fungal enzymes as it is from those of mammalian origin. Analysis of a rigid body shift of residues 190 to 302 shows that mucor pusillus pepsin displays one of the largest shifts relative to other aspartic proteinases (14.4 degrees relative to endothiapepsin) and that changes have occurred at the interface between the two rigid bodies to accommodate this large shift. A new sequence alignment has been obtained on the basis of the three-dimensional structure, enabling the positions of large insertions to be identified. Analysis of secondary structure shows the beta-sheet to be well conserved whereas alpha-helical elements are more variable. A new alpha-helix hN4 is formed by a six-residue insertion between positions 131 and 132. Most insertions occur in loop regions: -5 to 1 (five residues relative to porcine pepsin): 115 to 116 (six residues); 186 to 187 (four residues); 263 to 264 (seven residues); 278 to 279 (four residues); and 326 to 332 (six residues). The active site residues are highly conserved in mucor pusillus pepsin; r.m.s. difference with rhizopuspepsin is 0.37 A for 25 C alpha atom pairs. However, residue 303, which is generally conserved as an aspartate, is changed to an asparagine in mucor pusillus pepsin, possibly influencing pH optimum. Substantial changes have occurred in the substrate binding cleft in the region of S1 and S3 due to the insertion between 115 and 116 and the rearrangement of loop 9-13. Residue Asn219 necessitates a shift in position of substrate main-chain atoms to maintain hydrogen bonding pattern. Invariant residues Asp11 and Tyr14 have undergone a major change in conformation apparently due to localized changes in molecular structure. Both these residues have been implicated in zymogen stability and activation.

Sequential phospholipase activation in the stimulation of the neutrophil NADPH oxidase

Stimulation of human neutrophils with the chemotactic peptide fMet-Leu-Phe results in activation of a rapid, transient burst of oxidant secretion, which reaches a maximal rate by about 1 min after stimulation. This phase of oxidant secretion is then followed by intracellular oxidant production, which is detected by luminol chemiluminescence but not by assays such as cytochrome c reduction or scopoletin oxidation. The rapid phase of oxidant secretion requires increases in intracellular free Ca2+ and phospholipase A2 activity, but not the activities of phospholipase D or protein kinase C. In contrast, intracellular oxidant production requires the activities of phospholipase D and protein kinase C. A model is thus proposed suggesting the sequential activation of different phospholipases which activate oxidase molecules on the plasma membrane or else from the membranes of specific granules.

Activation of neutrophil reactive-oxidant production by synovial fluid from patients with inflammatory joint disease. Soluble and insoluble immunoglobulin aggregates activate different pathways in primed and unprimed cells

Cell-free synovial fluid from patients with rheumatoid arthritis stimulated the NADPH oxidase activity in human neutrophils, which reached a peak 15-20 min after addition. Insoluble immunoglobulin aggregates isolated from these fluids activated a similar pattern of oxidase activity. However, when synovial fluid was added to neutrophil suspensions which had been previously exposed to granulocyte-macrophage colony-stimulating factor, the stimulated oxidase activity was biphasic, in that an additional transient activity was observed which reached a peak within 5 min of addition. The additional neutrophil-stimulating activity could not be sedimented by centrifugation at 330,000 g-min, and only activated oxidase activity in neutrophils which had previously been primed. The neutrophil-stimulating activity in this soluble fraction was removed by Protein A affinity chromatography, and activity was recovered in eluates from this column. Thus activity in this soluble fraction from synovial fluid is attributed to the presence of soluble immunoglobulin aggregates. Whereas oxidase activity stimulated by the isoluble immunoglobulin aggregates was inhibited by staurosporine (and hence largely dependent on the activity of protein kinase C), the activity stimulated by the soluble immunoglobulin aggregates was staurosporine-insensitive. The soluble immunoglobulin aggregates were present at significantly higher levels in synovial fluids from patients with rheumatoid arthritis compared with those from other joint arthropathies. Thus rheumatoid synovial fluids possess heterogeneous immunoglobulin aggregates which activate neutrophils via distinct molecular pathways. As neutrophils within rheumatoid joints are primed, the soluble immunoglobulin aggregates are likely to be of importance in disease pathology.

Stimulation of neutrophils by insoluble immunoglobulin aggregates from synovial fluid of patients with rheumatoid arthritis

Insoluble immunoglobulin aggregates present in the synovial fluid of patients with rheumatoid arthritis have been examined for their ability to activate reactive oxidant and granule enzyme secretion from bloodstream neutrophils. These insoluble complexes activated luminol chemiluminescence, but did not activate O2-, H2O2 or granule enzyme secretion and did not activate lucigenin chemiluminescence, which also measures reactive oxidant secretion. Hence, the luminol chemiluminescence detected after activation by insoluble immunoglobulin aggregates must be due to intracellularly generated reactive oxidants, i.e. produced within phagolysosomes. Because reactive oxidant and granule enzyme secretion has occurred within rheumatoid joints, other mechanisms of neutrophil activation must exist.

Neutrophil function in whole blood and after purification: changes in receptor expression, oxidase activity and responsiveness to cytokines

Neutrophil function and plasma membrane receptor expression was measured in cell suspensions isolated by two separate procedures and in unfractionated whole blood. When cells were prepared by a combined dextran/ficoll procedure, their ability to generate reactive oxidants in response to fMet-Leu-Phe was greater than in corresponding cells isolated by a one-step procedure on Mono-Poly Resolving Medium (M-PRM). Cells prepared by both methods could be primed in vitro by rGM-CSF, but the priming ratio was greater in cells prepared by the latter method. The ability of neutrophils in whole blood to generate reactive oxidants in response to fMet-Leu-Phe was extremely low, but this was increased by more than 10 fold if the blood was pre-incubated with rGM-CSF. Similarly, expression of CD 11b and CD 16 was very low (or undetectable) in neutrophils in whole blood, but this was rapidly increased upon priming. Activation by PMA resulted in a down regulation of CD 16 expression as the receptor was shed from the cell surface. Neutrophils isolated by either the dextran/ficoll or the M-PRM method showed increased expression of receptors compared with those in whole blood, although this expression was lower in cells isolated by the latter method. These data indicate that the isolation procedures used to obtain purified neutrophils prime both receptor expression and oxidase function, although these effects are minimalised in isolation procedures using M-PRM. Furthermore, as CD 16 expression on neutrophils in whole blood is rapidly up-regulated during priming, it seems likely that, as for complement receptors, rapidly-mobilisable intracellular stores of this receptor exist.

Use of polymerase chain reaction for rapid detection of gene insertions in whole yeast cells

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Protein kinase C-dependent and -independent activation of the NADPH oxidase of human neutrophils

The protein kinase C inhibitor, staurosporine, inhibited NADPH oxidase activity of human neutrophils activated by phorbol myristate acetate. However, this inhibitor had no effect on either the initiation or the maximal rate of O2- secretion activated by the chemotactic peptide, fMet-Leu-Phe, but resulted in a more rapid termination of oxidant production. Similarly, staurosporine had no effect on the rapid (1 min) increase in luminol-dependent chemiluminescence activated by fMet-Leu-Phe, but the second (intracellular) phase of oxidant production was inhibited. The initial burst of oxidant production during phagocytosis was similarly protein kinase C-independent, but again the later phases of oxidase activity were staurosporine-sensitive. Neutrophils loaded with Quin-2 at concentrations sufficient to act as a Ca2+ buffer could not secrete O2- in response to fMet-Leu-Phe; although the initial (protein kinase C-independent) burst of luminol chemiluminescence was not observed in fMet-Leu-Phe-stimulated Ca2(+)-buffered cells, the second phase of (protein kinase C-dependent) oxidant production was largely unaffected. Hence, the initial burst of oxidant production activated by fMet-Leu-Phe, opsonized zymosan, and latex beads is independent of the activity of protein kinase C-dependent intracellular activation processes, but the activity of this kinase is required to extend or sustain the duration of oxidant production.

Receptor expression and oxidase activity in human neutrophils: regulation by granulocyte-macrophage colony-stimulating factor and dependence upon protein biosynthesis

Incubation of human bloodstream neutrophils with 50 u/ml recombinant granulocyte-macrophage colony-stimulating factor (rGM-CSF) "primed" the respiratory burst (as assessed by fMet-Leu-Phe stimulated luminol-dependent chemiluminescence) and resulted in a rapid (within 15 min) up-regulation of expression of CD11b and CD18 (as measured by FACS analysis). This rapid "priming" and modulation of receptor expression was not inhibited by cycloheximide and hence appeared to be independent of de novo protein biosynthesis. When neutrophils were incubated for up to 5 h in culture, the fluorescence distributions of CD11b and CD18 declined indicating the loss of expression of these receptors as the neutrophils aged, but in rGM-CSF treated suspensions receptor expression was maintained. When neutrophils were incubated in the presence of cycloheximide, they progressively lost their ability to generate reactive oxidants in response to fMet-Leu-Phe so that by 5 h incubation with this inhibitor they could only generate about 25% of the oxidative response stimulated in untreated cells, and the expression of CD16 and CD18 was grossly impaired. Similar effects were observed in rGM-CSF treated suspensions except that cycloheximide required longer incubation times (typically 4-5 h) before impairment of function or receptor expression occurred. These data show that de novo protein biosynthesis is required for both the maintenance of neutrophil function and also for the continued expression of some plasma membrane receptors.

Sequence of the variant thyroxine-binding globulin of Australian aborigines. Only one of two amino acid replacements is responsible for its altered properties

A form of thyroxine-binding globulin (TBG) with reduced affinity for hormone and increased susceptibility to heat and acid denaturation has been identified in Australian Aborigines (TBG-A). Results of heat denaturation of TBG established that the TBGA allele is X linked and has a frequency of 50.9% in Western Australian Aborigines. The sequence of an isolated TBGA allele differed at two positions from that of the normal TBG allele (TBGC). One substitution was in codon 191, ACA (threonine) rather than GCA (alanine), and the other was in codon 283, TTT (phenylalanine) instead of TTG (leucine). These nucleotide substitutions resulted in the loss of sites for the enzymes Bgl 1 and Tth 111 II, respectively. The nucleotide substitutions in the TBG-A allele was confirmed by digestion of genomic DNA segments amplified using the polymerase chain reaction. The Bgl 1 and Tth 111 II sites were absent in the genes of two Aboriginal men expressing TBG-A and were present in those of three Aboriginal and six Caucasian males expressing TBG-C. The TBG gene of a seventh Caucasian male possessed the Bgl 1 site but had lost the Tth 111 II site; sequencing of this allele revealed only the substitution in codon 283 identical to that in the TBGA allele. As the biochemical properties of TBGPhe-283 expressed by this individual were indistinguishable from normal TBGLeu-283, we believe that the abnormal properties of TBG-A are due to substitution of alanine for threonine at residue 191.

Protection of recently shorn sheep against adverse weather using plastic coats

Sheep cold stressed for 10.5 h had plastic coats applied then the cold stress was continued. In 9 of 10 sheep (test group) showing hypothermia at the time coats were applied, body temperatures had returned to near normal 2.5 h later and to normal in 13.5 h. One sheep severely hypothermic before the coat was applied did not improve and was killed after 2.5 h. Sheep that were cold stressed without coats (wet controls) developed marked hypothermia and were killed between 10.5 h and 21 h. Rectal temperatures remained normal in controls that were cold stressed with coats on (coated wet controls) and in the controls not subjected to wetting (dry controls). Plasma cortisol increased markedly in the cold stressed sheep until plastic coats were applied, but the levels had fallen to normal levels 20 h later. Serum thyroxine levels increased at a faster rate in the test group and in wet controls than in the dry controls and coated wet controls during the first 9 h of cold stress. In 4 sheep of the test group energy utilisation increased markedly and remained high for a variable time after coats were applied then gradually returned to pre-cold stress levels. Liver tyrosine aminotransferase levels of the wet controls were markedly elevated compared to levels found in the test group sheep killed 79.5 h after coats were applied. Histological changes in the spleen and liver of wet controls was absent or only mildly present in the test group sheep. There was severe depletion of muscle and liver glycogen in the wet controls compared with the test group sheep, which were similar to the dry controls and coated wet controls.

Variant thyroxine-binding globulin in serum of Australian aborigines: its physical, chemical and biological properties

Low serum total thyroxine (TT4) and triiodothyronine (TT3) is found in approximately 40% of Australian Aborigines. Studies were carried out to characterize the properties of thyroxine-binding globulin (TBG) in these Australian Aborigines to explain the observed reduction of thyroid hormone concentration in their serum. TBG from Aborigines with low serum TT4 concentrations was compared to TBG from Aborigines with normal TT4 concentration and Caucasians and American Blacks with normal or reduced serum TBG levels due to familial partial TBG deficiency. TBG from Aborigines with low serum TT4 concentrations had a reduced affinity for thyroid hormone (Ka). The Ka for T4 was 54% and for T3 30% of the Ka values for TBG from Aborigines with normal TT4 concentration or non-Aborigines. Maximal binding values were in agreement with TBG measurements by RIA for Aborigines with low or normal serum TT4 and for non-Aborigines. An increase in the rate of heat denaturation of TBG at temperatures from 54 to 60 C was also observed in sera from Aborigines with low TT4. The heat lability was lowered by 2 C. The low concentration of TT4 in serum of these Aborigines could not explain this higher heat lability of TBG since only addition of greater than 80-fold the physiologic T4 concentration obliterated the difference of heat inactivation by denaturation.(ABSTRACT TRUNCATED AT 250 WORDS)