Blocking intrahepatic deletion of activated CD8+ T cells by an altered peptide ligand

BACKGROUND: Activated CD8(+) T cells are retained by the healthy liver where the majority undergo apoptosis. The intrahepatic apoptosis of activated CD8(+) T cells is enhanced by the presence of SIINFEKL peptide. It is of great interest to identify strategies for maintaining intrahepatic T cell number and function in the presence of SIINFEKL peptides. AIM: Our aim was to test if low affinity peptides can block SIINFEKL peptide induced T cell deletion. METHODS: We used an in vivo model of intrahepatic CD8(+) T cell deletion with peptides of different affinities. RESULTS AND DISCUSSION: We show that the intrahepatic deletion of CD8(+) T cells by SIINFEKL peptide results in loss of in vivo cytotoxic T lymphocyte function. In contrast we show that a low affinity peptide (G4) does not result in intrahepatic deletion of CD8(+) T cells. High concentrations G4 peptide can however block intrahepatic deletion of activated CD8(+) T cells, and prevent loss of in vivo cytotoxicity due to SIINFEKL peptide. This is the first demonstration of blocking of SIINFEKL peptide induced CD8(+) T cell deletion in the liver, with enhancement of in vivo cytotoxicity.     

Computational model for cell migration in three-dimensional matrices

Although computational models for cell migration on two-dimensional (2D) substrata have described how various molecular and cellular properties and physiochemical processes are integrated to accomplish cell locomotion, the same issues, along with certain new ones, might contribute differently to a model for migration within three-dimensional (3D) matrices. To address this more complicated situation, we have developed a computational model for cell migration in 3D matrices using a force-based dynamics approach. This model determines an overall locomotion velocity vector, comprising speed and direction, for individual cells based on internally generated forces transmitted into external traction forces and considering a timescale during which multiple attachment and detachment events are integrated. Key parameters characterize cell and matrix properties, including cell/matrix adhesion and mechanical and steric properties of the matrix; critical underlying molecular properties are incorporated explicitly or implicitly. Model predictions agree well with experimental results for the limiting case of migration on 2D substrata as well as with recent experiments in 3D natural tissues and synthetic gels. Certain predicted features such as biphasic behavior of speed with density of matrix ligands for 3D migration are qualitatively similar to their 2D counterparts, but new effects generally absent in 2D systems, such as effects due to matrix sterics and mechanics, are now predicted to arise in many 3D situations. As one particular sample manifestation of these effects, the optimal levels of cell receptor expression and matrix ligand density yielding maximal migration are dependent on matrix mechanical compliance.     

Evaluation of remotely delivered leuprolide acetate as a contraceptive agent in female elk (Cervus elaphus nelsoni)

Practical application of fertility control technology in free-ranging wild ungulates often requires remote delivery of the contraceptive agent. The objective of this investigation was to evaluate the potential of remote delivery of leuprolide acetate for suppressing fertility in female elk (Cervus elaphus nelsoni). Fifteen captive adult female elk were randomly allocated to one of three experimental groups. Six elk were injected intramuscularly with a dart containing leuprolide, and the remaining nine elk received the same formulation without leuprolide. We determined pregnancy rates, suppression of luteinizing hormone (LH) and progesterone concentrations, and reversibility of treatments during 1 August 2002 to 3 September 2003. Leuprolide formulation caused a decrease in concentrations of LH and progesterone, temporary suppression of ovulation and steroidogenesis, and effective contraception (100%) for one breeding season. These results extend the practical application of this contraceptive agent to include dart delivery, where in the absence of such technology, wild elk must first be captured and restrained before treatment.     

The anatomy of the sheep cervix and its influence on the transcervical passage of an inseminating pipette into the uterine lumen

The anatomy of the sheep cervix is highly variable between animals and may explain the differing success of transcervical AI between individuals. This study aims to quantify the variation in cervical morphology between ewes and investigate the relationship between cervical anatomy and cervical penetration. Two series of reproductive tracts were collected. Series A: 132 adult anoestrous ewes, and series B: 165 cycling adult ewes and ewe lambs which were identified as luteal or non-luteal based on the presence of a corpus luteum. The morphology of the cervical external os was classified as slit, papilla, duckbill, flap or rose. An inseminating pipette was inserted into the lumen and the depth of penetration recorded. The cervix was opened longitudinally, its length recorded, the number of cervical rings counted and the arrangement of those rings graded. The maximum depth of cervical penetration was affected by cervical grade (series A: P=0.021; series B: P=0.037) and the stage of the oestrous cycle (P=0.008). Grade 1 cervices were more penetrable than grade 2, with grade 3 the least penetrable and non-luteal cervices could be penetrated further than luteal cervices. The distribution of os types differed with age, with rose types more common in adult ewes, and papilla os types more common in ewe lambs. These results indicate that the depth of cervical penetration is affected by the anatomy of the cervical lumen. Cervices with a less convoluted lumen (grade 1) were more penetrable. Non-luteal cervices are likely to have higher oestradiol concentrations than luteal, stimulating cervical relaxation and enabling deeper penetration. The difference in os types with age may be contributable to a morphological alteration at parturition.     

Growth of Bifidobacterium longum BB536 in medida (fermented cereal porridge) and their survival during refrigerated storage

AIMS: To develop medida, a Sudanese fermented thin porridge as a probiotic dietary adjunct with high total solids. METHODS AND RESULTS: Fifteen per cent brown rice flour of 2-day-old malted paddy and skim milk were used for formulation. Levels of 2.25, 4.5 and 10% of added skim milk were studied. The initial pH was 6.7 and fermentation was run to a final pH of 4.4 using culture of Bifidobacterium longum BB 536. The highest count of 9.9 +/- 0.07 log CFU ml(-1) was obtained with 10% of added skim milk. The total solids at this level was 21%, 11.1 times more compared with the traditionally prepared medida using un-malted brown rice. The viscosity was low and the flowing characteristic was stable. The final productions of lactic and acetic acids were 56.8 +/- 0.80 and 56.3 +/- 2.00 mumol ml(-1) respectively. The high ratio of acetate to lactate decreased as fermentation continues due to the increase in the rate of lactate production. Under refrigerated storage the count of B. longum BB 536 remained relatively stable during the first week (9.7 +/- 0.10 log CFU ml(-1)) then subsequently decreased by 0.9 log CFU ml(-1) in the following week. CONCLUSIONS: The results of this study demonstrated that fermented medida made from malted brown rice is a suitable food system for the delivery of B. longum BB 536 with a relatively stable shelf life. SIGNIFICANCE AND IMPACT OF THE STUDY: The present study is the first attempt to prepare fermented medida from malted flour with bifidobacteria having the highest total solids while still maintaining the flowing characteristics. Previous studies on medida did not go beyond the use of alpha amylase enzyme and pure lactic acid bacteria isolates from spontaneously fermented dough.     

Okra-leaf accessions of the upland cotton (Gossypium hirsutum L.): genetic variability in agronomic and fibre traits

Okra-leaf types of the upland cotton have the potential to be competitive to the normal-leaf types in yield and fibre quality, in addition to its potential resistance to insect pests and drought. Okra-leaf cotton accessions, collected at Cotton Research Institute, Faisalabad, Pakistan, were evaluated in respect of genetic variance and relative performance in half- and full-sib crosses (combining ability) for 2 years. Variation due to parents x years interaction was significant for lint percentage, seed weight and earliness index, resulting in moderately low but significant genetic variance across environments (years) for these traits. Interaction of environment with general combining ability was significant for seed yield, seed weight, and earliness index. General combining ability variation, contributed by females and males together, accounted for 71% of the total variation available for seed cotton yield, 60% of that for seed weight and height to node ratio each, and 75% of that for earliness index. Specific combining ability variation accounted for 85% and 51% of the total variation available for lint percentage and staple length, respectively. The contribution of female parents to general combining ability variation was higher than that of male parents for seed cotton yield, seed weight, height to node ratio, and earliness index. Okra-leaf accessions HR-VO-MS and HR107-NH were predicted to produce progenies having high yield, HR109-RT high lint percentage, while HR100-Okra, Gambo-Okra and HR-VO-1 were predicted to impart early crop maturity to their progenies by reason of their good general combining ability for these traits. The results also provided evidence that genes controlling high yield in HR-VO-MS and HR107-NH were different from those controlling high yield in HR109-RT. The set of genes controlling the high earliness index in HR100-Okra and that in HR-VO-MS also appeared to differ in expression.     

Peptides mimicking Vibrio cholerae O139 capsular polysaccharide elicit protective antibody response

Vibrio cholerae is the etiological agent of cholera. V. cholerae serogroup O1 had been, until 1992, the only serogroup responsible for large epidemics and pandemics of cholera. In 1992, a new serotype of V. cholerae emerged in South-East Asia that caused a massive outbreak of cholera in India and neighboring countries. The new serotype was named V. cholerae O139. The main differences between V. cholerae O139 and O1 are that the former possesses a capsular polysaccharide and different lipopolysaccharide. Capsular polysaccharides are, in general, T-independent antigens giving rise to poor immune responses lacking immunological memory. In order to overcome this, monoclonal antibodies against the capsular polysaccharide of V. cholerae O139 were used to screen different phage-displayed random peptide libraries. Eight different phage clones were selected and characterized using enzyme immunoassay with the monoclonal antibodies, and then tested for specificity by competition with V. cholerae O139 capsular polysaccharide. Selected peptides were sequenced, synthesized and conjugated to bovine serum albumin (BSA) and keyhole limpet hemocyanin (KLH). The conjugated peptides were used to immunize mice. It is evident that the anti-peptide mouse antibodies bind to the V. cholerae O139 capsular polysaccharide. In addition, the anti-peptide antibodies are protective in a suckling mouse model. The protective efficacy is both specific and dose-dependent. A PCT (PCT/IT2003/000489) with the publication number WO 2004/056851 has been filed for the sequences of the eight peptides.     

Phage phiC31 integrase: a new tool in plastid genome engineering

Plastid transformation offers the unique advantages of high-level transgene expression and increased transgene containment compared with conventional transgenic technologies. The process relies on the homologous recombination machinery of the plastid incorporating foreign DNA into the plastome, which restricts the method to species where this type of incorporation works well. However, Pal Maliga and colleagues have recently reported a novel approach for integrating foreign DNA into the plastid genome that works independently of homologous recombination.