Solid-phase differential display and bacterial expression systems in selection and functional analysis of cDNAs

Differential gene expression can be expected during activation and differentiation of cells as well as during pathological conditions, such as cancer. A number of strategies have been described to identify and understand isolated differentially expressed genes. The differential display methodology has rapidly become a widely used technique to identify differentially expressed mRNAs. In this chapter we described a variant of the differential display method based on solid-phase technology. The solid-phase procedure offers an attractive alternative to solution-based differential display because minute amounts of sample can be analyzed in considerably less time than previously. The employed solid support, monodisperse super paramagnetic beads, which circumvents precipitation and centrifugations steps, has also allowed for optimization of the critical enzymatic and preparative steps in the differential display methodology. We also described how bacterial expression can be used as a means to elucidate gene function. An efficient dual-expression system was presented, together with a basic concept describing how parallel expression of selected portions of cDNAs can be used for production of cDNA-encoded proteins as parts of affinity-tagged fusion proteins. The fusion proteins are suitable both for the generation of antibodies reactive to the target cDNA-encoded protein and for the subsequent affinity enrichment of such antibodies. Affinity-enriched antibodies have proved to be valuable tools in various assays, including immunoblotting and immunocytochemical staining, and can thus be used to localize the target cDNA-encoded protein to certain cells in a tissue section or even to a specific cell compartment or organelle within a cell. High-resolution localization of a cDNA-encoded protein would provide valuable information toward the understanding of protein function.

Odor identification in normal aging and early Alzheimer's disease: effects of retrieval support

Odor sensitivity and identification were examined in normal aging and early Alzheimer's disease (AD). The aims were to investigate AD as associated with lower odor sensitivity, odor identification as a function of retrieval support, and the relationship between global cognitive functioning (Mini-Mental State Exam [MMSE]; M. F. Folstein, S. E. Folstein, & P. R. McHugh, 1975) and olfactory performance. Results indicated intact odor sensitivity but deficient odor identification in AD. Both groups benefited from cues in identification, and the size of the gains was equally large in AD patients and controls. The finding of no selective benefit from retrieval support in AD suggests that a degradation of olfactory knowledge contributes to the odor identification deficits in these patients. MMSE and identification were positively related, whereas MMSE and olfactory sensitivity were unrelated. These findings suggest that the AD-related olfactory impairment stems from lesions in cortical rather than peripheral structures.

A recombinant vaccinia virus based ELISPOT assay detects high frequencies of Pol-specific CD8 T cells in HIV-1-positive individuals

OBJECTIVES

HIV-1-specific CD8 T cells are considered to be critical in anti-HIV responses. It is important to quantify these cells and to determine their antigenic targets. Here quantification of interferon (IFN)-gamma secreting, virus-specific cells was achieved with an enzyme linked immuno spot (ELISPOT) assay.

METHODS

Peripheral blood mononuclear cells (PBMC) were infected with recombinant vaccinia vectors expressing HIV-1 genes (gag, pol, env or nef) and added to wells precoated with anti-IFN-gamma monoclonal antibodies. Spot forming cells (SFC), i.e. antigen-specific T cells were detected 24 h later by the addition of biotinylated anti-IFN-gamma monoclonal antibodies, followed by avidin-bound biotinylated horseradish peroxidase.

RESULTS

In a cohort of 19 patients, of whom 15 were on highly active antiretroviral therapy, 18 had primed T cells directed against one or more HIV-1 antigens (P < 0.0001). Pol-specific T cells routinely dominated the CD8 response with frequencies up to 2000 SFC per 10(6) PBMC. In HLA A*0201-positive patients, the vaccinia vectors detected much higher frequencies of SFC than haplotype-restricted peptides. Elimination of CD8 T cells resulted in > 90% loss of antigen-specific SFC when vaccinia virus was used as a vector. The number of CD8 SFC exceeded the number of memory cells detected in limiting dilution assays by > 1 log10, whereas a correlation was found between the frequency of effector cells detected by both ELISPOT and MHC class I peptide tetramer assays.

CONCLUSIONS

Vaccinia virus vectors used in ELISPOT assays are useful for determining the frequency and specificity of CD8 T cells for individual HIV-1 gene products. The dominance of cytolytic T lymphocytes (CTL) recognizing pol proteins suggests that this antigen should be considered in vaccine strategies.

Dendritic cells generated from blood monocytes of HIV-1 patients are not infected and act as competent antigen presenting cells eliciting potent T-cell responses

The CTL response to HIV-I can be vigorous, but antigen presenting cell requirements have not been studied in detail. To approach this question, we have examined the dendritic cell populations that can be obtained from the blood of HIV-1 infected individuals. We studied 13 asymptomatic patients, who spanned a wide range of plasma viremia and CD4 counts. We show here that sizeable numbers of mature dendritic cells can be generated from nonproliferating progenitors in the blood of HIV + patients using a recently developed approach. The procedure involves two steps. The first step or 'priming' phase is a 7 day culture of T-cell depleted mononuclear cells in medium supplemented with GM-CSF and IL-4. The second step or 'differentiation' phase requires the exposure to monocyte conditioned medium. The yields of DCs from HIV + individuals were comparable to normal blood donors, 0.4 - 3 x 10(6) mature dendritic cells from 50 ml of blood. Strong APC function was evident for both the proliferation of allogeneic T-cells in the MLR, and the generation by syngeneic T-cells of class I restricted, CTL responses to influenza virus. A panel of dendritic cell restricted markers are expressed, including CD83, p55, and perinuclear CD68. By semi-quantitative PCR analysis, the cytokine derived cells did not express HIV-1 DNA. We suggest that these blood derived dendritic cells will be effective for studies of immune responses to HIV-1 antigens and may be considered as adjuvants for active immunotherapy.

Effects of extracellular calcium on the subcellular translocation of bovine parathyroid PKC isozymes

The release of parathyroid hormone is regulated by the extracellular concentration of Ca2+ through a sensor(s) on the surface of the parathyroid cells, but few details are known on the further relay of the signal inside the cell. Activation of protein kinase C (PKC) isozymes is associated with their translocation from the cell soluble fraction to the particulate fraction of the cell. Therefore, identification of a subcellular localization of a PKC isozyme in parathyroid cells as a response to changes in extracellular Ca2+ should be an indication for its putative role in signal transduction coupled to the Ca2+ sensor. We have determined the subcellular localization of six PKC isozymes (alpha, betaI, betaII, epsilon, zeta, and iota) in nonstimulated parathyroid cells and in those treated with low (0.5 mM) and high (3.0 mM) extracellular Ca2+ by confocal microscopy. At the physiological concentration of serum Ca2+, all PKC isozymes studied were localized mainly to the cytosol, although to different extents. Low extracellular Ca2+ caused a redistribution of PKCalpha to the periphery of the cells. In contrast, PKCbetaI, -epsilon, -zeta, and -iota were translocated to the periphery of the cells at high extracellular Ca2+. These results indicate that PKCalpha, -betaI, -epsilon, -zeta, and -iota are involved in the response of parathyroid cells to changes in extracellular Ca2+.

Characterization of a molten globule state of bovine carbonic anhydrase III: loss of asymmetrical environment of the aromatic residues has a profound effect on both the near- and far-UV CD spectrum

Bovine muscle carbonic anhydrase (isoenzyme III; BCAIII) exhibited a three-state unfolding process at equilibrium upon denaturation in guanidine hydrochloride (GuHCl). The stable folding intermediate appeared to be of molten globule type. The stability towards GuHCl in terms of mid-point concentrations of denaturation were very similar for BCAIII and human CAII (HCAII). It was further demonstrated that the aromatic amino acid residues contributed significantly to the circular dichroism (CD) spectrum in the far-UV wavelength region during the native-->molten globule state transition. Thus, the ellipiticity change at 218 nm was shown to monitor the loss of tertiary interactions of aromatic side chains at the first unfolding transition as well as the rupture of secondary structure at the second unfolding transition. Similar aromatic contributions to the far-UV CD spectrum, but with varying magnitudes, were also noted for BCAII and HCAII, further emphasizing that interference of aromatic residues should not be neglected at wavelengths that normally are assigned to secondary structural changes.

Odor identification in normal aging and early Alzheimer's disease: effects of retrieval support

Odor sensitivity and identification were examined in normal aging and early Alzheimer's disease (AD). The aims were to investigate AD as associated with lower odor sensitivity, odor identification as a function of retrieval support, and the relationship between global cognitive functioning (Mini-Mental State Exam [MMSE]; M. F. Folstein, S. E. Folstein, & P. R. McHugh, 1975) and olfactory performance. Results indicated intact odor sensitivity but deficient odor identification in AD. Both groups benefited from cues in identification, and the size of the gains was equally large in AD patients and controls. The finding of no selective benefit from retrieval support in AD suggests that a degradation of olfactory knowledge contributes to the odor identification deficits in these patients. MMSE and identification were positively related, whereas MMSE and olfactory sensitivity were unrelated. These findings suggest that the AD-related olfactory impairment stems from lesions in cortical rather than peripheral structures.

Semantic mediation of age-related deficits in episodic recognition of common odors

In the present research, the relationship between various semantic memory functions and episodic odor memory across the adult life span is addressed. In contrast to earlier evidence that odors may be encoded and stored as unique, nonlinguistic whole percepts, the present work suggests that episodic odor information is mediated by factors that can be subsumed under the rubric of semantic memory. Specific olfactory knowledge, such as perceived familiarity and identifiability, is strongly and positively related to episodic odor memory performance. In contrast to research using verbal and visual stimuli, proficiency in complex verbal intellectual abilities, such as vocabulary and fluency, seems to be of minor importance in memory for olfactory information. In agreement with earlier findings, this research indicates that episodic odor memory deteriorates across the adult life span. A similar negative age trend was observed for odor naming. Most importantly, statistical control of odor naming resulted in the elimination of age-related odor memory deficits. These results suggest that age-related failures in accessing specific semantic information of odors determine largely age-related deficits in episodic odor recognition.

Expression of ciliary tektins in brain and sensory development

Many types of neural tissues and sensory cells possess either motile or primary cilia. We report the first mammalian (murine testis) cDNA for tektin, a protein unique to cilia, flagella, and centrioles, which we have used to identify related proteins and genes in sensory tissues. Comparison with the sequence database reveals that tektins are a gene family, spanning evolution from Caenorhabditis elegans (in which they correlate with touch receptor cilia) and Drosophila melanogaster, to Mus musculus and Homo sapiens (in which they are found in brain, retina, melanocytes, and at least 13 other tissues). The peptide sequence RPNVELCRD, or a variant of it, is a prominent feature of tektins and is likely to form a functionally important protein domain. Using the cDNA as a probe, we determined the onset, relative levels, and locations of tektin expression in mouse for several adult tissues and embryonic stages by Northern blot analysis and in situ hybridization. Tektin expression is significant in adult brain and in the choroid plexus, the forming retina (primitive ependymal zone corresponding to early differentiating photoreceptor cells), and olfactory receptor neurons of stage embryonic day 14 embryos. There is a striking correlation of tektin expression with the known presence of either motile or primary cilia. The evolutionary conservation of tektins and their association with tubulin in cilia and centriole formation make them important and useful molecular targets for the study of neural development.

Gene discovery in the wood-forming tissues of poplar: analysis of 5, 692 expressed sequence tags

A rapidly growing area of genome research is the generation of expressed sequence tags (ESTs) in which large numbers of randomly selected cDNA clones are partially sequenced. The collection of ESTs reflects the level and complexity of gene expression in the sampled tissue. To date, the majority of plant ESTs are from nonwoody plants such as Arabidopsis, Brassica, maize, and rice. Here, we present a large-scale production of ESTs from the wood-forming tissues of two poplars, Populus tremula L. x tremuloides Michx. and Populus trichocarpa 'Trichobel.' The 5,692 ESTs analyzed represented a total of 3,719 unique transcripts for the two cDNA libraries. Putative functions could be assigned to 2,245 of these transcripts that corresponded to 820 protein functions. Of specific interest to forest biotechnology are the 4% of ESTs involved in various processes of cell wall formation, such as lignin and cellulose synthesis, 5% similar to developmental regulators and members of known signal transduction pathways, and 2% involved in hormone biosynthesis. An additional 12% of the ESTs showed no significant similarity to any other DNA or protein sequences in existing databases. The absence of these sequences from public databases may indicate a specific role for these proteins in wood formation. The cDNA libraries and the accompanying database are valuable resources for forest research directed toward understanding the genetic control of wood formation and future endeavors to modify wood and fiber properties for industrial use.

Case control study of feline Borna disease in Sweden

A questionnaire-based, retrospective case-control study of 174 Swedish cats was used to identify possible risk factors for feline Borna disease. The questionnaire consisted of 32 questions on a wide range of subjects, including lifestyle and possible modes of virus transmission. Two control groups were used: a healthy-control and a hospital-control. Variables with significant odds ratios in either the Borna disease:healthy-control or Borna disease:hospital-control comparison were included in multiple logistic regression analyses. Overall, the models suggested that feline Borna disease has a predominantly rural/woodland distribution, that affected cats were more likely to be males than females and intact than neutered, and that they were more likely than not to have hunted mice. The results indicate that, in contrast to other feline viral infections, Borna disease virus is not readily transmitted between cats. The natural reservoir of the virus is unknown. The fact that exposure to mice by hunting was a risk factor for the disease suggests that rodents may be subclinically infected and act as virus carriers.

Modality memory across the adult life span: evidence for selective age-related olfactory deficits

Item memory and memory for modality format were assessed in young, young-old, and old women. Participants were presented with mixed-modality lists and items were related to four modality formats: auditory, olfactory, visual, and tactile. Memory was tested immediately after and 48 hours after inspection. Results indicated that both the young-old and old adults were disproportionately impaired in source memory relative to item memory, although they were not selectively impaired for any type of information in item memory. However, when recollection of source was required, the older age groups generated disproportionately more confusions to auditory items for olfactory information at delayed testing, and the reverse was true for the auditory information, which was most often confused with odors. Taken together, these results suggest that elaborating and reconstructing the source of olfactory information may be particularly difficult for older adults.

The amygdala and individual differences in human fear conditioning

While animal research on fear conditioning suggests crucial involvement of the amygdala, this has not been corroborated in humans when using subtractive neuroimaging methodology. Correlation analyses might be more able to reveal relations between individual differences in conditionability and central neural activity. Hence, we performed a directed search for amygdalar participation in human fear conditioning by correlating central and autonomic nervous activity. [15O]Butanol positron emission tomography evaluated regional cerebral blood flow (rCBF) in six subjects before and after aversive conditioning to visual snake stimuli. Non-specific electrodermal fluctuations (EDA) were recorded simultaneously. A significant positive correlation was obtained between conditioned EDA and conditioned rCBF in the right amygdala (r = 0.75, p < 0.05), supporting involvement of the amygdala in human fear conditioning.

Semantic factors in episodic recognition of common odors in early and late adulthood: a review

Information on long-term memory for common odors is discussed. Olfactory parameters (i.e. familiarity, recognition, identification) and their relationship to current memory theory are highlighted. Emphasis is focused on the impact of semantic memory on episodic odor recognition. In contrast to previous research suggesting that verbal/semantic factors play a negligible role in olfactory memory, the present review indicates that episodic odor information is mediated by factors that can be subsumed under the rubric of semantic memory. Specific odor knowledge, such as perceived familiarity and identifiability, is strongly and positively related to episodic odor memory performance. Age-related impairments in various olfactory and cognitive parameters and the potential detrimental effects in episodic odor memory are discussed. Finally, the issue of whether olfactory memory should be conceptualized as an independent process, or whether it shares characteristics with memory for verbal and visual information, is addressed.

Role of annexins in endocytosis of antigens in immature human dendritic cells

We have evaluated the uptake of a soluble protein antigen, denitrophenylated human serum albumin (DNP-HSA), and two different intracellular bacteria; Chlamydia trachomatis serovar L2 and Mycobacterium tuberculosis strain H37Ra, by immature human dendritic cells. These were generated by culturing progenitor cells from blood in the presence of cytokines (granulocyte-macrophage colony-stimulating factor and interleukin-4). Dendritic cells play a crucial part in antigen presentation for the induction of T-cell-dependent immune responses in various tissues. Recently, macropinocytic and phagocytic activity has been shown for immature dendritic cells of mouse, rat and human origin. In the present study, macropinocytosis characterized the uptake of the soluble protein-antigen DNP-HSA, whereas the C. trachomatis were ingested via receptor-mediated endocytosis in coated pits, and opsonized M. tuberculosis via phagocytosis. To follow the intracellular routes of the antigens, their positions were compared with the localization of annexins, a family of Ca(2+)-and phospholipid-binding proteins, involved in membrane fusion, aggregation and transport of different vesicles. To elucidate further the intracellular pathway of the antigens, two other proteins, lysosome-associated membrane protein-1 (LAMP-1) and cathepsin D, were labelled. They are known to colocalize with major histocompatibility complex class II compartments in the immature dendritic cells. We observed a distinct translocation of annexin V to DNP-HSA containing endosomes, and annexin III to vesicles with C. trachomatis. Furthermore, annexin III, IV and V redistributed to phagosomes with M. tuberculosis. Both LAMP-1 and cathepsin D colocalized with DNP-HSA endosomes, and with phagosomes with M. tuberculosis. Thus, immature human dendritic cells have the capacity to phagocytose. Moreover, the handling of these antigens by dendritic cells may represent three distinct intracellular pathways, albeit some properties and compartments are shared.

Male aerial display and reversed sexual size dimorphism in the dunlin

Reversed sexual size dimorphism, with males smaller than females, is common in waders. The aerial display hypothesis suggests that sexual selection in males favours aerial agility, and hence small size, in species with male display flights. We tested this hypothesis in the dunlin, Calidris alpinaDisplay flights were uncommon in the early breeding season but increased markedly when females began laying. Male display areas were largely overlapping, and display flight seemed to be mainly an advertising signal to potential mates. Display rate, as well as proportion of time spent in aerial display, increased with decreasing male size. During aerial display, small males also performed costly hovering flights more often and for relatively longer than large males. These results support the aerial display hypothesis.Copyright 1997 The Association for the Study of Animal Behaviour1997The Association for the Study of Animal Behaviour

The melanocortin 1, 3, 4 or 5 receptors do not have a binding epitope for ACTH beyond the sequence of alpha-MSH

ACTH(1-39), and several shorter N- and/or C-terminally truncated fragments of ACTH, with and without N-terminal acetylation and/or C-terminal amidation, were tested for binding on a single eukaryotic cell line transiently and independently expressing the melanocortin MC1, MC3, MC4 and MC5 receptors. The results show that none of these MC receptors has specific binding epitopes for the ACTH peptides beyond the amino acid sequence of alpha-MSH, when tested for their ability to compete with 125I-labelled [Nle4,D-Phe7]alpha-MSH and ACTH. The MC3 receptor favours the natural desacetylated N-terminal end of the ACTH peptides, and it has generally more than 10-fold higher affinity for the ACTH peptides than the MC4 receptor. Considering earlier anatomical localisation data, together with the present data, we suggest that the MC3 receptor is the most likely candidate of the MC receptors to mediate the short-loop negative feedback release of corticotrophin-releasing factor (CRF) caused by ACTH/MSH peptides.

DISSOCIATIVE RECOMBINATION WITH ION STORAGE RINGS

The development of heavy-ion storage-cooler rings for atomic physics has made it possible to produce high-quality beams of molecular ions that are internally cold. The stored molecular-ion beam is immersed in a cold electron bath, which gives a beam of low divergence and small cross-sectional area. The electron cooler also serves as a target for electron-molecular ion collision experiments. This allows the study of dissociative recombination of cold molecules with respect to cross sections, branching ratios, and angular distributions at an unprecedented luminosity.

Indirect calorimetry during treadmill walking--a study of two methods

Walking is a complex process and the physiotherapist must focus on physical signs as well as functional and practical tests to evaluate treatment. Measurement of energy expenditure during level walking is a useful objective parameter for assessing walking as being a valuable supplement to evaluate the outcome of physiotherapy. This study had two purposes. The first purpose was to investigate whether sampling and measurement of oxygen consumption were reproducible when using two different devices during walking on a treadmill. A second purpose was to find out whether the measurements were sensitive enough to reveal differences in energy expenditure and respiratory quotient (RO) during different walking speeds. Ten healthy students (mean age 22 years; range 20-25 years) volunteered in the test-retest of a slightly adjusted Deltatrac metabolic monitor. Thirteen volunteers (mean age 45 years; range 31-57 years) participated in the test-retest of Sensormedics 2900. In the first test, the subjects walked for 10 min in order to get a steady state both at an individual comfortable speed and at a preset speed. The retest was done with the same design and within 2 weeks. Nobody experienced any discomfort during the tests. The repeatability of measuring energy expenditure and RQ was acceptable for both methods and the methods were sensitive in revealing differences in energy expenditure during different walking speeds. The RQ were, however, too low when using the Deltatrac monitor, probably as a result of low air flow. We therefore conclude that only the method using Sensormedics 2900 may be used for the evaluation of energy expenditure during walking on a treadmill.

Age-related differences in episodic odour recognition: the role of access to specific odour names

This study addressed the relationship between semantic memory variables and episodic odour recognition across the adult lifespan. Young (19-34 years), young-old (60-69 years), and old women (70-79 years) were tested in a number of measures of semantic memory: letter fluency, category fluency, vocabulary, odour familiarity, and odour naming. Odour recognition memory was assessed on two occasions: immediately after and 48 hours after inspection. Young women outperformed both groups of older women in odour recognition and odour naming, although the two older age groups did not differ. For all age groups, performance declined from immediate to delayed testing. Individual differences in fluency and vocabulary did not predict performance in odour recognition. Rather, odour recognition was related to the subjects' specific semantic knowledge of the odour, as indexed by familiarity and accuracy in odour naming. Hierarchical regression analyses indicated that age and odour naming were the most potent variables in predicting performance in both immediate and delayed odour recognition. Controlling for odour naming resulted in the effect of age disappearing, indicating the pivotal role of accessibility of odour names for successful episodic odour recognition, and for age-related differences in odour recognition.

Binding of cyclic and linear MSH core peptides to the melanocortin receptor subtypes

We report here the binding of 5-, 6- and 7-amino-acid-long linear and cyclic core peptides of MSH (melanocyte-stimulating hormone) to cells transiently expressing the human melanocortin MC1, MC3, MC4 and MC5 receptors. The results show that, in contrast to the natural peptides, the core peptides did not differentiate between the melanocortin MC3 and MC4 receptors. All tested cyclic peptides had much lower affinities than their corresponding linear homologues. Interestingly, the relative loss of binding due to the cyclisation did not change as the ring size decreased. Therefore, decreasing the ring size does not seem to force the peptide into a more unfavourable conformation.

Human dendritic cells handling of binding, uptake and degradation of free and IgG-immune complexed dinitrophenylated human serum albumin in vitro

The handling of free and IgG-complexed dinitrophenylated human serum albumin (DNP-HSA) by human dendritic cells (DC) cultured with granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4) was studied. It has been shown that the amount of uncomplexed or IgG-complexed antigen required by DC to start an immune response is low compared with other antigen-presenting cells. We therefore examined whether such efficient presentation of immune complexes is due to an enhanced Fc gamma RII-mediated endocytosis or to a specialized and efficient antigen handling, i.e., macropinocytosis. The Fc gamma RII expression was found to be heterogeneous on the GM-CSF- and IL-4-cultured DC, i.e. it ranges from low to high expression. The handling of antigen and immune complexes revealed, that the level of binding and uptake of IgG-DNP-HSA complexes by in vitro expanded DC is low compared with free antigen. Uncomplexed DNP-HSA is probably handled either by endocytosis via receptors being more abundant and/or efficient than the Fc gamma RII or via non-receptor-mediated endocytosis. The binding and uptake of IgG-complexed DNP-HSA was blocked by anti-Fc gamma RII antibody, indicating the specificity of the interaction.

Improved zinc and iron absorption from breakfast meals containing malted oats with reduced phytate content

The absorption of Zn or Fe from breakfast meals containing oat porridge prepared from malted and soaked oats and a control porridge made from untreated oats was measured in human subjects. The effect on Zn and Fe absorption of reducing the phytate content of oat-porridge meals was examined in each subject by extrinsic labelling of porridge with 65Zn and of bread rolls with 55Fe and 59Fe, and measuring whole-body retention and the erythrocyte uptake of isotopes. Each experiment comprised nine to ten subjects. The absorption of Zn from malted-oat porridge with a phytate (inositol hexaphosphate) content of 107 mumol was 18.3%, and significantly higher (P < 0.05) than from the control porridge containing 432 mumol phytate (11.8%). Fe absorption from the meal containing malted-oat porridge with 107 mumol phytate (Expt 2) was also significantly improved (P < 0.05) compared with that from the meal containing control porridge with 437 mumol phytate. The average increase in Fe absorption was 47%, or from 4.4 to 6.0%. In the breakfast meal containing malted porridge with 198 mumol phytate (Expt 3) the increase in Fe absorption was not significantly improved. Even though the phytate content was reduced to a greater extent in Expt 3 than Expt 2, the average increase in Fe absorption in Expt 3 was only 25% more than that from the meal containing control porridge (with 599 mumol phytate), depending on the higher absolute amount of phytate. In conclusion, an improvement in Zn and Fe absorption from oat products can be achieved by practising malting and soaking in the processing of oats. This may be of importance in the prevention of mineral deficiency in vulnerable groups.

Multiple affinity domains for the detection, purification and immobilization of recombinant proteins

Affinity systems based on specific molecular recognition are valuable tools for detection, purification and immobilization of recombinant proteins. Here, novel multipartite affinity fusion vectors were assembled and investigated to allow flexible binding and elution conditions. The rationale for the assembly of different combinations of affinity domains was to take advantage of the wide variety of molecular interactions of these domains for purification, solubilization, detection and immobilization. In total, seven different affinity tags representing five different types of tag-ligand interactions were studied: (i) monoclonal antibodies-peptides (T7-tag and FLAG peptide); (ii) streptavidin-peptide (Strep-tag); (iii) hexahistidyl-metal ions (His6-tag; (iv) bacterial receptors-serum proteins (staphyloccal protein A-Fc and streptococcal protein G-serum albumin); (v) streptavidin-biotin (in vivo biotinylated peptide). Selected tags were evaluated for the production and purification of Escherichia coli DNA polymerase I (Klenow fragment). On the basis of the results, a vector (pAff2c) was assembled using a novel combination of affinity domains: (i) an in vivo biotinylated peptide; (ii) a His6 sequence, and (iii) a highly soluble serum albumin binding region. Using these three affinities, a wide variety of conditions can be employed for both the binding and the elution steps.

Treatment of psoriatic arthritis with extracorporeal photochemotherapy and conventional psoralen-ultraviolet A irradiation

OBJECTIVE

To study the use of combined photopheresis and psoralen-ultraviolet A irradiation (PUVA) in the treatment of psoriatic arthritis.

METHODS

Eight patients with psoriasis and sero-negative arthritis received photopheresis for 12 weeks, followed by photopheresis plus PUVA for another 12 weeks. Clinical and laboratory examinations were performed every 3 months for up to 1 year after therapy.

RESULTS

Four patients experienced a marked improvement of joint symptoms that lasted for > or = 12 months post-therapy (74% decrease in the Ritchie articular index; P < 0.01). Prior to therapy, these patients had a higher CD4:CD8 ratio than the poor responders. Only minor laboratory changes occurred.

CONCLUSION

A more extensive trial of photopheresis plus PUVA in psoriatic arthritis is warranted.

Cloning and sequencing of human gp330, a Ca(2+)-binding receptor with potential intracellular signaling properties

We present here the complete primary structure of human gp330, the human variant of the principal kidney autoantigen causing Heymann membranous glomerulonephritis in rats. The deduced 4655 amino acid residues give a calculated molecular mass of 519636 Da for the mature protein and consists of a probable 25-amino-acid N-terminal signal peptide sequence, an extracellular region of 4398 amino acids, a single transmembrane-spanning domain of 23 amino acids, and an intracellular C-terminal region of 209 amino acid residues. Three types of cysteine-rich repeats characteristic of the low density lipoprotein receptor (LDLR) superfamily are present in human gp330. In the extracellular region, there are a total of 36 LDLR ligand-binding repeats, comprising four distinct domains, 16 growth factor repeats separated by eight YWTD spacer regions, and one epidermal growth factor-like repeat. No consensus cleavage sequence for the processing endoprotease furin is detected in human gp330. The intracellular tail contains not only two copies of the F(X)NPXY coated-pit mediated internalization signal characteristic of LDLR superfamily members, but also intriguing and potentially functional motifs including several Src-homology 3 recognition motifs, one Src-homology 2 recognition motif for the p85 regulatory subunit of phosphatidylinositol 3-kinase, and additional sites for protein kinase C, casein kinase II and cAMP-/cGMP-dependent protein kinase. There is approximately 77% amino acid identity between human and rat gp330 with minor differences between the extracellular and intracellular regions. Recently gp330 has been implicated in Ca2+ regulation in the parathyroid, the placenta, and the renal tubule, but its overall physiological and pathological role still remains uncertain.

A general bacterial expression system for functional analysis of cDNA-encoded proteins

A general system for functional analysis of cDNA-encoded proteins is described. The basic concept involves the expression in Escherichia coli of selected portions of cDNAs in an approach toward the understanding of the function of the corresponding proteins. A selected cDNA is expressed as part of a fusion protein used for immunization to elicit antibodies, and a corresponding fusion protein, having the cDNA-encoded portion in common, for purification of target protein-specific antibodies. This antiserum could be used for functional analysis of the cDNA-encoded protein, e.g., by immunohistology. Two general expression vector systems for E. coli have been constructed, both (i) designed with multiple cloning sites in three different reading frames, (ii) having their protein production controlled by the tightly regulated T7 promoter, and (iii) enabling affinity purification of the expressed target proteins by fusions to IgG-binding domains derived from staphylococcal protein A or a serum albumin-binding protein derived from streptococcal protein G, respectively. This novel system has been evaluated by expressing five cDNAs, isolated from prepubertal mouse testis by a differential cDNA library screening strategy. All five clones could be expressed intracellularly in E. coli as fusion proteins with high production levels, ranging from 4 to 500 mg/liter, and affinity purification yielded essentially full-length products. Characterization of affinity-purified antibodies revealed that there exists no cross-reactivity between the two fusion systems and that such antibodies indeed could be used for immunohistology. The implications for the described system for large-scale functional analysis of cDNA libraries are discussed.

The effects of a shortened postoperative mobilization programme after flexor tendon repair in zone 2

The effects of a shortened post-operative mobilization programme following flexor tendon repair in zone 2 in the hand were examined in a prospective, randomized study. 91 digits in 82 patients were included in the study. All injured tendons were repaired within 24 hours and all patients were subjected to the same mobilization programme during the first 6 weeks using a passive flexion-active extension régime. After 6 weeks the patients were randomized into two groups; in group A full activity was allowed after 8 weeks while in group B unrestricted use of the injured hand was not allowed until 10 weeks after the tendon repair. Functional results were compared using the Louisville, Tsuge and Buck-Gramcko assessment systems. Grip-strength was measured 16 weeks after repair, subjective assessment of hand function was recorded on a visual analogue scale, and absence from work was registered. No significant differences were observed between the groups regarding functional results, rupture rates, grip strength or subjective assessment, but absence from work was reduced by 2.1 weeks with the shorter mobilization programme. Using the described régime, full activity can be encouraged 8 weeks after flexor tendon repair in zone 2 of the hand without adverse effects on functional results or increased risk of rupture of the repair.

Increase of tryptophan in serum and in cerebrospinal fluid of patients with HIV infection during zidovudine therapy

A high percentage of patients with human immunodeficiency virus infection presents with decreased tryptophan concentrations in serum and cerebrospinal fluid. In parallel degradation products of tryptophan like kynurenine and quinolinic acid are increased. We investigated the behavior of tryptophan concentrations in 14 patients with HIV infection before and during treatment with zidovudine, and we found a significant increase of tryptophan in serum and cerebrospinal fluid after 4-14 months of therapy. In parallel, neopterin concentrations decreased significantly. Moreover, an association existed in cerebrospinal fluid between the degree of tryptophan increase and neopterin decrease. Thus, treatment with zidovudine contributes to a gradual normalization of tryptophan metabolism in patients with HIV-1 infection. The data imply that zidovudine therapy is associated not only with a reduction of virus replication but also immune activation is reduced.

Inactivated influenza virus, when presented on dendritic cells, elicits human CD8+ cytolytic T cell responses

Inactivated or subunit virus preparations have been excellent vaccines for inducing antibody responses. Generation of cytolytic T cell responses, however, is thought to require replicating virus, primarily to provide sufficiently large amounts of cytoplasmic proteins for processing and presentation on major histocompatibility complex class I molecules by antigen-presenting cells. Potent human CD8+ cytolytic T cell responses to live replicating influenza A virus are generated when dendritic cells are used as the antigen-presenting cells. Here, we demonstrate that dendritic cells pulsed with poorly replicating, heat- or ultraviolet-inactivated influenza virus, induce equally strong CD8+ cytolytic T lymphocyte responses. The cytotoxic T lymphocytes are generated in the apparent absence of CD4+ helper cells or exogenous cytokines. Active viral protein synthesis is not required to charge class I molecules on dendritic cells. When pulsed with inactivated virus, < 1% of dendritic cells express nonstructural protein 1, which is only synthesized in the infectious cycle. To be optimally effective, however, the inactivated virus must retain its fusogenic activity, and presumably access the cytoplasm of dendritic cells. The data indicate, therefore, that dendritic cells require only small amounts of viral protein to charge class I molecules, most likely via traditional class I processing pathways. These results reopen the potential use of inactivated virus preparations as immunogens for cytotoxic T lymphocyte responses.

Mobilization of annexin V during the uptake of DNP-albumin by human dendritic cells

Dendritic cells play a crucial role in antigen presentation in various tissues. The endocytic capacity of these cells has been regarded as minimal, but recent work on dendritic cells from mouse spleen has disclosed that the fluid-phase traffic through late endosomes is as active in dendritic cells as in other antigen-presenting cell types. We show that cultured human dendritic cells express the annexins I, III, IV, V and VI, as detected by immunofluorescence staining. The annexins are cytosolic Ca(2+)-dependent proteins with the ability to promote vesicle aggregation and membrane fusion through their capacity to bind to membrane phospholipids. Annexin I and VI appeared to outline the cytoskeleton and the plasma membrane in cultured human dendritic cells. Studies using confocal laser scanning microscopy showed that during the endocytosis of fluorescent dinitrophenyl-conjugated albumin by dendritic cells, there was a redistribution of annexin V which was found to colocalize with vesicles containing dinitrophenyl-FITC-conjugated albumin.