Decompressive laminectomies with clinical improvement but persistent myelographic blocks

Surgical decompression for spinal cord compression secondary to metastatic epidural neoplasms is a common procedure. Preoperative myelography is nearly always done, and clinical improvement postoperatively is assumed to be correlated with relief of the radiologically demonstrated subarachnoid block. Three cases with postoperative clinical improvement but persistent subarachnoid blocks are reported. The recognition of this is important to avoid unnecessary secondary surgery.     

Structure-activity relationships of four 11-hydroxyestrones isomeric at the C-9 and C-11 positions

The synthesis of 11 alpha-hydroxyestrone, 11 alpha-hydroxy-9 beta-estrone, and 11 beta-hydroxy-9 beta-estrone are presented. The reduction of 11-keto-9 beta-estrone 17-ethyleneketal by sodium in ethanol or sodium borohydride resulted in 11-hydroxy-9 beta-estrones. The 11-hydroxyl group configurations were opposite to expectations: sodium in boiling ethanol afforded the axial 11 beta-hydroxy-9 beta-estrone, while sodium borohydride in boiling tetrahydrofuran gave the equatorial 11 alpha-hydroxy-9 beta-estrone. In immature rat uterotropic bioassays using subcutaneous injections, 11 alpha-hydroxyestrone was 2 times as active as 11 alpha-hydroxy-9 beta-estrone, and 11 beta-hydroxyestrone was 10 times as active as 11 beta-hydroxy-9 beta-estrone.     

Detection and sequence analysis of hepatitis B virus integration in peripheral blood mononuclear cells

A PCR-based technique was used to detect hepatitis B virus (HBV) integration in peripheral blood mononuclear cells from patients with chronic hepatitis B. Integrated HBV DNA sequences, with virus-cell junctions located in the cohesive region between direct repeat 1 (DR1) and DR2, were found in 2 of 10 studied patients.     

A cruciform-dumbbell model for inverted dimer formation mediated by inverted repeats

Small inverted repeats (small palindromes) on plasmids have been shown to mediate a recombinational rearrangement event in Escherichia coli leading to the formation of inverted dimers (giant palindromes). This recombinational rearrangement event is efficient and independent of RecA and RecBCD. In this report, we propose a cruciform-dumbbell model to explain the inverted dimer formation mediated by inverted repeats. In this model, the inverted repeats promote the formation of a DNA cruciform which is processed by an endonuclease into a linear DNA with two hairpin loops at its ends. Upon DNA replication, this linear dumbbell-like DNA is then converted to the inverted dimer. In support of this model, linear dumbbell DNA molecules with unidirectional origin of DNA replication (ColE1 ori ) have been constructed and shown to transform E.coli efficiently resulting in the formation of the inverted dimer. The ability of linear dumbbell DNA to transform E.coli suggests that the terminal loops may be important in bypassing the requirement of DNA supercoiling for initiation of replication of the ColE1 ori.     

Expression of fibronectin splicing variants in organ transplantation: a differential pattern between rat cardiac allografts and isografts

Allograft rejection is associated with infiltration of inflammatory cells and deposition of extracellular matrix proteins. The extent to which diversity in the extracellular matrix regulates inflammatory cell function in transplants remains unclear. One group of extracellular matrix proteins, termed fibronectins (FNs), exhibits inherent diversity as a consequence of alternative splicing in three segments: EIIIA, EIIIB, or V. Although the EIIIA segment has documented functions in mesenchymal cell differentiation, neither this segment nor the EIIIB segment have been tested for effects specific to leukocyte functions. By contrast, the V region can include the CS-1 segment to which leukocytes may adhere through alpha 4 beta 1 integrins. In this study, we demonstrate that EIIIA+, EIIIB+, and V+ FN variants are synthesized, primarily by macrophages in distinct temporal and spatial patterns in two rat cardiac transplant models: either with antigenic challenge, allografts, or without challenge, isografts. The ratio of EIIIA inclusion into FN increases by day 1 in allografts and isografts and remains high until allografts are rejected (approximately 7 days) but falls to normal levels in tolerated isografts (day 6). EIIIB+ FN ratios in allografts peak later than do EIIIA+ FNs (day 4). EIIIB+ FN ratios remain relatively low in isografts. Interestingly, EIIIA+ and EIIIB+ FNs are deposited prominently in the myocardium of rejecting allografts in close association with infiltrating leukocytes, and FN expression and deposition are prominent at sites of infarction. By contrast, these FNs are largely restricted to the epicardium and to a lesser degree in the immediately adjacent myocardium in isografts. CS-1+ FNs increase in allografts and isografts at 3 hours after transplantation but are particularly prominent in allografts 1 to 3 days before rejection. Our data suggest that FN splicing variants have a differential role in the effector functions of leukocytes in allografts and isografts and provide a foundation for testing their function on leukocytes and a rationale for FN-based therapeutics to modulate allograft rejection in transplant recipients.