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)