The dependence of the conformation of cyclosporin A (CPA), a cyclic undecapeptide with potent immunosuppressive activity, on the type of solvent environment is examined using the computer simulation method of molecular dynamics (MD). Conformational and dynamic properties of CPA in aqueous solution are obtained from MD simulations of a CPA molecule dissolved in a box with water molecules. Corresponding properties of CPA in apolar solution are obtained from MD simulations of CPA in a box with carbontetrachloride. The results of these simulations in H2O and in CCl4 are compared to each other and to those of previous simulations of crystalline CPA and of an isolated CPA molecule. The conformation of the backbone of the cyclic polypeptide is basically independent of the type of solvent. In aqueous solution the beta-pleated sheet is slightly weaker and the gamma-turn is a bit less pronounced than in apolar solution. Side chains may adopt different conformations in different solvents. In apolar solution the hydrophobic side chain of the MeBmt residue is in an extended conformation with its hydroxyl group hydrogen bonded to the backbone carbonyl group. In aqueous solution this hydrophobic side chain folds over the core of the molecule and the mentioned hydrogen bond is broken in favor of hydrogen bonding to water molecules. The conformation obtained from the MD simulation in CCl4 nicely agrees with experimental atom-atom distance data as obtained from nmr experiments in chloroform. In aqueous solution the relaxation of atomic motion tends to be slower than in apolar solution.

Chemical Phenomena↗

PubMedDate not supplied

Induction of heme oxygenase-1 in the donor reduces graft immunogenicity.

There is increasing evidence that the induction of the enzyme heme oxygenase-1 (HO-1) improves both graft function and survival. Although it has been shown that HO-1 promotes graft protection, it remains unknown whether it reduces graft immunogenicity by modulating dendritic cells. In the current experiment, we investigated the impact of HO-1 induction on frequencies and trafficking of donor-derived dendritic cells (DCs). Kidneys from DA rats were transplanted into untreated Lewis recipients. Donor animals were treated with cobalt protoporphyrin (CoPP; 5 mg/kg IP) 24 hours prior to organ harvesting to induce HO-1. Controls remained untreated or received zinc protoporphyrin (ZnPP; 20 mg/kg, IP) to block HO-1 induction. Analyses of grafts, spleens, lymph nodes and blood of Lewis recipients were performed at days 1 and 3 posttransplantation. Donor-specific DCs were determined by flow cytometry using haplotype-specific mAb against RT1(ab) and mAb against OX62(+) antigens. Cell markers (CD4/CD8(+) T cells, ED1(+) monocytes, MHC class II(+) CD86(+) DC) were measured by immunohistochemical staining. T-cell alloreactivity of recipient splenocytes was measured by ELISPOT. Induction of HO-1 reduced frequencies of donor-derived DCs in the graft and recipient compartments, which was associated with reduced frequencies of CD4(+) T cells and CD8(+) T cells and alloreactivity. Expression of costimulatory molecule CD86 and MHC class II antigens were also reduced, although not significantly. Thus, induction of HO-1 reduced graft immunogenicity. These mechanisms may explain the protective effects of HO-1 induction.

Animals↗

PubMedDate not supplied

CT staging of esophageal carcinoma in patients treated by primary radiation therapy and chemotherapy.

Primary radiation therapy with concurrent chemotherapy is under study as definitive and palliative therapy for patients with esophageal carcinoma. To evaluate the correlation between CT staging and outcome, we retrospectively reviewed the CT scans of 48 patients treated with primary radiation therapy and concurrent chemotherapy and correlated CT staging with disease-free survival, overall survival, and site of relapse. Excluding one patient who was understaged and six patients who died of problems unrelated to esophageal carcinoma, mean survival of CT stage I, II, and III patients was 14.7, 21.3, and 5.2 months, respectively. When the CT stage is modified by the presence of nodal involvement on CT, the mean survival of stage IIn and IIIn (nodes greater than 1.5 cm in diameter) and stage IV patients (distant metastases) was 16.4, 19.2, and 10.6 months, respectively. Despite thickening of the esophageal wall greater than 3.0 cm in five patients with stage IIn cancer, mean survival was still 19.2 months. Patients with pericardial effusion had the worst survival of only 4.3 months. Stage II patients had a significantly longer (p less than 0.05) disease-free period than all other groups and the difference between stage II and III patients was highly significant (p less than 0.01). Stage II patients were also more likely to be disease-free at the time of death or last follow-up (p less than 0.05). Computed tomographic staging of esophageal carcinoma is useful in radiation therapy treatment planning and predicting outcome of patients managed with a nonsurgical technique of concurrent radiation and chemotherapy.

Adult↗

PubMedDate not supplied

Therapeutic effect of arginine-glycine-aspartic acid peptides in acute renal injury.

1. Previous studies from our laboratory have suggested that arginine-glycine-aspartic acid (RGD) peptides, serving as a decoy, may prevent tubular obstruction in the ischaemic model of acute renal failure. Specifically, we have demonstrated that: (i) stressed tubular epithelial cells reverse the polarity of integrin receptors from the predominantly basolateral location to the apical cell membrane as a part of a more generalized process of the loss of epithelial cell polarity; (ii) depletion of integrins expressed on the basal cell surface leads to the loss of anchorage to the basement membrane and cell desquamation; (iii) expression of integrin receptors on the apical cell membrane leads to indiscriminate interactions (e.g. the adhesion of desquamated cells to the cells remaining in situ), thus initiating the process of tubular obstruction; and (iv) conglomeration of the desquamated cells via integrin receptors further aggravates tubular obstruction. 2. Importantly, these integrin-based interactions can be blocked by synthetic RGD peptides. The linear RGD peptide injected into the renal artery upon release of the renal artery clamp prevented the elevation of proximal tubular hydrostatic pressure characteristically seen in animals with renal ischaemia that received injection of the vehicle of an inactive peptide. 3. In vivo study of RGD peptides in ischaemic acute renal failure in rats demonstrated attenuation of renal injury and accelerated recovery of renal function. 4. Using linear RGD peptide labelled with 99mTc; we have shown that this probe was retained in ischaemic kidneys. 5. To visualize RGD binding sites at the cellular level, we performed a mapping using fluorescent derivatives of two RGD peptides, a cyclic biotinylated (Bt)-RGD peptide and a linear Rhodamine green-labelled (RhoG)-RGD peptide. 6. The findings suggest that the binding sites for RGD peptide are represented by the alphaVbeta3 integrin in the vasculature and some desquamated cells, whereas the majority of the desquamated cells bind Bt-RGD via beta1 integrins. 7. These findings were further tested using cultured endothelial cells co-incubated with leucocytes. When co-incubation experiments were performed in the presence of cyclic RGD pentapeptide, the adhesion of HL-60 cells to both control and hypoxic endothelial monolayers was significantly reduced.

Acute Kidney Injury↗

PubMedDate not supplied

AIDS-related body cavity-based lymphoma. A case report.

BACKGROUND: Body cavity-based lymphomas are rare malignancies in human immunodeficiency virus (HIV)-infected patients, but because of their unusual clinical, morphologic and immunophenotypic features, they are recognized as a distinct subgroup of lymphomas connected to human herpesvirus 8 (HHV-8) infection. CASE: A 39-year-old, HIV-positive, homosexual man was admitted to the hospital because of a left-sided pleural effusion that contained malignant lymphoid cells. He responded partially to a low-dose cyclophosphamide/doxorubycin/vincristine/prednisone regimen and died five months after the diagnosis of lymphoma. On cytology, the sediments contained exclusively large, round, neoplastic, lymphoid cells with abundant basophilic cytoplasm and large, round nuclei with prominent nucleoli. Many cells had immunoblastic features, and some had plasmocytoid differentiation. Mitotic figures were numerous. On flow cytometry, the homogeneous population of large cells expressed CD45, CD38, HLA-DR and CD7 positivity. Other specific T-, B- and NK-cell markers tested negative. Polymerase chain reaction demonstrated Epstein-Barr virus (EBV) and HHV-8 in the malignant effusion. CONCLUSION: Primary effusion from lymphoma with molecular evidence of HHV-8 and EBV coinfection represents a distinct clinical and morphologic entity in AIDS patients. However, immunophenotypic markers of malignant clones can be diverse in different cases.

AIDS-Related Opportunistic Infections↗