Lung resident mesenchymal stem cells isolated from human lung allografts inhibit T cell proliferation via a soluble mediator

Development of allograft rejection continues to be the major determinant of morbidity and mortality postlung transplantation. We have recently demonstrated that a population of donor-derived mesenchymal stem cells is present in human lung allografts and can be isolated and expanded ex vivo. In this study, we investigated the impact of lung resident mesenchymal stem cells (LR-MSCs), derived from allografts of human lung transplant recipients, on T cell activation in vitro. Similar to bone marrow-derived MSCs, LR-MSCs did not express MHC II or the costimulatory molecules CD80 or CD86. In vitro, LR-MSCs profoundly suppressed the proliferative capacity of T cells in response to a mitogenic or an allogeneic stimulus. The immunosuppressive function of LR-MSCs was also noted in the absence of direct cell contact, indicating that LR-MSCs mediated their effect predominantly via a soluble mediator. LR-MSCs isolated from lung transplant recipients demonstrated PGE(2) secretion at baseline (385 +/- 375 pg/ml), which increased in response to IL-1beta (1149 +/- 1081 pg/ml). The addition of PG synthesis inhibitors (indomethacin and NS-398) substantially abrogated LR-MSC-mediated immunosuppression, indicating that PGE(2) may be one of the major soluble mediators impacting T cell activity. This is the first report to demonstrate that human tissue-derived MSCs isolated from an allogeneic environment have the potential to mediate immunological responses in vitro.     

Differential regulation of trypsinogen mRNA translation: full-length mRNA sequences encoding two oppositely charged trypsinogen isoenzymes in the dog pancreas.

In the absence of changes in functional mRNA levels, stimulation of the pancreas with caerulein, a peptide analog of cholecystokinin, has been previously shown to increase the synthesis of anionic but not cationic trypsinogen. To look for structure-function correlations, a high-yield, full-length cDNA library has been constructed from canine pancreatic poly(A)+ mRNA. Full-length clones coding for the two major trypsinogen isoenzyme forms have been identified by colony hybridization and verified by in vitro translation of hybrid-selected mRNA in the presence of microsomal membranes and an optimal redox potential. Disulfide-bonded translation products were separated and identified by two-dimensional isoelectric focusing-sodium dodecyl sulfate-gel electrophoresis. Nucleotide sequence analysis allowed us to deduce the amino acid sequences for the anionic and cationic forms of canine trypsinogen, which contain 232 and 231 residues, respectively (77% amino acid identity), and the 15-residue amino terminal signal sequences (53% amino acid identity) associated with the two presecretory forms. Measurements of relative and absolute mRNA levels, when related to relative protein synthesis values, indicated that the translational efficiency of anionic trypsinogen mRNA exceeded that of cationic trypsinogen mRNA by 1.5- to 2.9-fold under basal conditions. Analysis of the 5' noncoding regions of trypsinogen mRNAs revealed a striking conservation of sequence (10 of 12 bases) between dog and rat anionic trypsinogen forms. This contrasted markedly with the divergence of the 5' noncoding regions observed between dog anionic and cationic trypsinogen mRNAs.     

Male pseudohermaphroditism: diagnosis in cell culture.

Testicular feminization is a classic form of complete male pseudohermaphroditism. The individuals have a normal XY karyotype but unambiguously female external genitalia. They have congenital complete insensitivity to androgen due to an X-linked mutation. In four patients (from tow families with several affected members) with the typical phenotype of testicular feminization, a severe deficit of specific androgen-binding activity was detected in cultured fibroblasts from labium majus skin. Measurement of this activity in genital skin fibroblasts improves the differential diagnosis in patients with complete or imcomplete male pseudohermaphroditism before puberty.     

A 3D model of muscle reveals the causes of nonuniform strains in the biceps brachii

Biomechanical models generally assume that muscle fascicles shorten uniformly. However, dynamic magnetic resonance (MR) images of the biceps brachii have recently shown nonuniform shortening along some muscle fascicles during low-load elbow flexion (J. Appl. Physiol. 92 (2002) 2381). The purpose of this study was to uncover the features of the biceps brachii architecture and material properties that could lead to nonuniform shortening. We created a three-dimensional finite-element model of the biceps brachii and compared the tissue strains predicted by the model with experimentally measured tissue strains. The finite-element model predicted strains that were within one standard deviation of the experimentally measured strains. Analysis of the model revealed that the variation in fascicle lengths within the muscle and the curvature of the fascicles were the primary factors contributing to nonuniform strains. Continuum representations of muscle, combined with in vivo image data, are needed to deepen our understanding of how complex geometric arrangements of muscle fibers affect muscle contraction mechanics.     

The role of the complement cascade in ischemia/reperfusion injury: implications for neuroprotection

BACKGROUND: The complement cascade plays a deleterious role in multiple models of ischemia/reperfusion (I/R) injury, including stroke. Investigation of the complement cascade may provide a critical approach to identifying neuroprotective strategies that can be effective at clinically relevant time points in cerebral ischemia. This review of the literature describes the deleterious effects of complement activation in systemic I/R models and previous attempts at therapeutic complement inhibition, with a focus on the potential role of complement inhibition in ischemic neuroprotection. Translation of these concepts into ischemic stroke models and exploration of related neuroprotective strategies are also reviewed. SUMMARY OF REVIEW: We performed a MEDLINE search to identify any studies published between 1966 and 2001 dealing with complement activation in the setting of I/R injury. We also searched for studies demonstrating up-regulation of any complement components within the central nervous system during inflammation and/or ischemia. CONCLUSIONS: The temporal and mechanistic overlap of the complement cascade with other biochemical events occurring in cerebral I/R injury is quite complex and is only beginning to be understood. However, there is compelling evidence that complement is quite active in the setting of acute stroke, suggesting that anticomplement strategies should be further investigated through genetic analysis, nonhuman primate models, and clinical investigations.     

Neostriatal administration of somatostatin:differential effect of small and large doses on behavior and motor control

The administration of small doses of somatostatin (SRIF) (0.01 and 0.1 microgram) into the neostriatal complex of unrestrained, freely moving rats induced general behavioral excitation associated with a variety of stereotyped movements, tremors, and a reduction of rapid eye movements (REM) and deep slow wave sleep (SWS). In contrast, the higher doses of SRIF (1.0 and 10.0 microgram) caused movements to be uncoordinated and frequently induced more severe difficulties in motor control such as contralateral hemiplegia-in-extension which restricted or completely prevented the expression of normal behavioral patterns. As a result, the animals appeared drowsy and inhibited. Analysis of the sleep-waking cycle revealed prolonged periods of a shallow SWS while REM sleep and deep SWS were markedly reduced; electroencephalogram recordings revealed periods of dissociation from behavior. The administration of endocrinologically inactive as well as the active analogues of SRIF failed to induce effects comparable with those observed after the administration of the same dose of the native hormone (10.0 microgram).