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Biomedical subjects

J Clarke

Publications and source records attributed to J Clarke.

At least 289 records · Page 16Linked to original sources
PubMed1986

The association of antivascular endothelial cell antibody with hyperacute rejection: a case report.

Early graft loss almost always occurs when recipients of a renal allograft develop antibody directed against antigens specific for donor vascular endothelial cells (VECs) and peripheral blood monocytes. In studies involving recipients of human leukocyte antigen identical, living-related grafts exhibiting preformed antibody to the VEC antigens of their donors, the median onset of rejection was 3 days after transplantation. Although preformed antibody to VEC antigens has been related in numerous articles to early graft loss, there has never been a published report of anti-VEC antibody leading to hyperacute rejection. We report a patient who hyperacutely rejected a renal allograft after undergoing a donor-specific transfusion protocol with her mother in which the kidney was removed in less than 24 hours. Nine months later the patient had a retransplantation with an allograft from a cadaveric donor. The cadaveric graft was again hyperacutely rejected, and this kidney was removed immediately. Anti-VEC/monocyte antibody directed against both donors was detected in the patient's pretransplant sera. With the exception of a positive B-lymphocyte crossmatch with her mother, all the standard crossmatches were negative.

Adolescent↗
PubMed1985

Molecular cloning and physical mapping of the genome of fish lymphocystis disease virus.

A defined and complete gene library of the fish lymphocystis disease virus (FLDV) genome was established. FLDV DNA was cleaved with EcoRI, BamHI, EcoRI/BamHI and EcoRI/HindIII and the resulting fragments were inserted into the corresponding sites of the pACYC184 or pAT153 plasmid vectors using T4 DNA ligase. Since FLDV DNA is highly methylated at CpG sequences (Darai et al., 1983; Wagner et al., 1985), an Escherichia coli GC-3 strain was required to amplify the recombinant plasmids harboring the FLDV DNA fragments. Bacterial colonies harboring recombinant plasmids were selected. All cloned fragments were individually identified by digestion of the recombinant plasmid DNA with different restriction enzymes and screened by hybridization of recombinant plasmid DNA to viral DNA. This analysis revealed that sequences representing 100% of the viral genome were cloned. Using these recombinant plasmids, the physical maps of the genome were constructed for BamHI, EcoRI, BestEII, and PstI restriction endonucleases. Although the FLDV genome is linear, due to circular permutation the restriction maps are circular.

Animals↗
PubMed1985

Separation of complementary strands of plasmid DNA using the biotin-avidin system and its application to heteroduplex formation and RNA/DNA hybridizations in electron microscopy.

A method for the separation of complementary strands with the help of the biotin-avidin system is described. Restriction fragments were terminally labeled at both ends with biotinylated nucleotides. The DNA was cut by a second restriction enzyme, and the fragments were bound to an avidin agarose column. The non-biotinylated strands were eluted with 0.1 M NaOH, and the biotin-labeled strands were subsequently released from the column by elution with 50% guanidine isothiocyanate/formamide. Contamination of the separated strands by complementary single strands was less than 4%.-Separated linear single strands of the vector pEMBL were prepared. On annealing with recombinant circular DNA a substitution loop is formed which provides position and orientation markers for the unambiguous electron microscopic analysis of heteroduplexes or hybrids formed with the inserted sequences. -The terminal biotin label was visualized by complex formation with a streptavidin-ferritin conjugate.

Avidin↗
PubMed1985

The structure of precursor mRNAs and of excised intron RNAs in chloroplasts of Euglena gracilis.

Partially spliced precursor mRNAs (pre-mRNAs) in the steady-state population of RNA from chloroplasts of Euglena gracilis were found by electron microscopy. The structure and the frequency of the pre-mRNAs of the psbA gene (the gene for the 32-kd protein of photosystem II), which is split by four introns in Euglena chloroplasts was analysed by electron microscopy. A chloroplast DNA (cpDNA) fragment containing the psbA gene from Euglena, was cloned into a pEMBL vector. The single-stranded recombinant phage DNA of the coding strand was prepared and hybridized with cpRNA. The majority of hybrids were formed with mature mRNA, but approximately 8% of the hybrids were formed with pre-mRNAs. The pre-mRNAs were either unspliced or incompletely spliced. A detailed analysis of the structure and the frequency of the pre-mRNAs of the psbA gene showed that the four introns are neither spliced out in a strictly random way, nor in a 5'-3' or 3'-5' direction. Introns 2 and 3 are preferentially spliced out first, intron 1 intermediately and intron 4 is generally spliced out last. However, this sequence is not a strict rule. We conclude that the introns can be spliced independently, each one at a different rate. The coding strand from a fragment of the psbA gene was separated and annealed with low mol. wt. cpRNA, which was isolated from an agarose gel. Small circular hybrids were found at the positions of the four introns, demonstrating for the first time covalently closed circular excised intron RNAs (iRNAs) in chloroplasts.

Animals↗
PubMed1985

A putative transforming gene of Jijoye virus differs from that of Epstein-Barr virus prototypes.

The P3HR-1 strain of Epstein-Barr virus (EBV), a nontransforming clonal derivative of Jijoye (EBV), is characterized by a deletion of 6.6 kb involving part of the BamHI-W repeats and the adjacent region including the NotI repeats. In the transforming parental Jijoye virus this region differs from the corresponding regions in B95-8 or M-ABA virus. The HindIII-B fragments which carry this region from both Jijoye and prototype M-ABA (EBV) viruses have been cloned and subclones have been constructed which contain the left-hand part of HindIII-B from the HindIII to the BglII site (BglII-delta C fragment). By restriction enzyme analysis the inserts were found to be of equal size (6.3 kb) but to differ in their restriction enzyme pattern. Heteroduplexes formed under stringent conditions in the presence of T4 gene 32 protein revealed a substitution loop of 1750 +/- 200 nucleotides. Heteroduplex formation under nonstringent conditions showed that the substituted sequences are partially homologous to each other, with the regions of nonhomology confined to three distinct areas of 100 to 200 nucleotides. The partial homology observed between both regions indicates that they have evolved from a common ancestor. By hybridization of a Jijoye virus subclone containing only sequences of the substituted region to Northern blots a 2.8-kb polyadenylated transcript was detected indicating that the substituted region is expressed in Jijoye cells.

Cell Line↗
PubMed1985

Circulatory effects of intravenous and oral acebutolol in acute myocardial infarction.

The hemodynamic dose-response effects of intravenous (25 and 50 mg) and oral (200 and 400 mg) acebutolol were compared in a randomized between-group study in men within 17 hours of an acute uncomplicated myocardial infarction. Six subjects were evaluated in each of the four groups. After a 1-hour control period, hemodynamic variables and plasma drug concentrations were determined at 15 (intravenous therapy only), 30, 60, 90, 120, and 240 minutes after dosing. At the doses studied, hemodynamic dose-response effects were not evident after either intravenous or oral acebutolol. In all groups acebutolol reduced systolic and mean systemic arterial pressure, heart rate, cardiac output, and stroke volume. Pulmonary artery occluded pressure and systemic vascular resistance were transiently increased. Maximum changes developed between 15 and 30 minutes after intravenous dosing and between 1 and 2 hours after oral dosing. However, there were substantial reductions in cardiac output (-0.7 L/min/m2; P less than 0.05) by 30 minutes after oral dosing. Effects lasted for 2 hours after intravenous dosing and for 4 hours after oral dosing. Our data confirm the hemodynamic safety of acebutolol after acute myocardial infarction. The relevance of the time-dependent hemodynamic differences between intravenous and oral initiation of beta-blockade to the overall goal of reducing myocardial oxygen requirements after acute coronary artery occlusion merits closer examination.

Acebutolol↗
PubMed1985

The vascular endothelial cell antigen system.

Vascular endothelial cells (VEC) are clearly immunogenic and express antigens unique to vascular endothelial cells. The observation that peripheral blood monocytes also express this VEC antigen system made prospective testing feasible. Preformed antibody to the VEC/monocyte antigen system of the donor usually leads to graft rejection in HLA-identical combinations, but antibody directed against donor monocytes exclusively (monocyte-specific antigens) appears to be benign. Clearly the VEC antigen system is an important immunogen in HLA-identical living-related donor combinations--and, in addition, this antigen system may be equally important in the non-HLA-identical combinations. The identification of antibody directed against the VEC/monocyte antigens of the donor is frequently masked by the concurrent development of anti-HLA antibody. Preliminary family segregation studies support the concept of genetic linkage between the VEC/monocyte antigen system and the major histocompatibility complex. A group of 153 consecutive, prospective monocyte crossmatches performed have yielded approximately a 7% incidence of positive monocyte crossmatches, with traditional crossmatches being negative. This frequency of patients sensitized to the VEC/monocyte antigens of the donor could conceivably account for up to 70% of the observed early graft loss in living-related donors. We think a positive monocyte crossmatch to the donor in the presence of positive reactivity to concordant VEC and monocytes remains a contraindication to transplantation.

Endothelium↗
PubMed1985

Identification of the antibody to vascular endothelial cells in patients undergoing cardiac transplantation.

Acute cardiac dysfunction occurred in four cardiac allograft recipients with negative donor-specific lymphocyte crossmatches. In two recipients the transplanted heart was removed and the patients were maintained on bypass for several hours until a second cardiac allograft was available. In these patients the second transplanted heart also underwent acute dysfunction. The lymphocyte crossmatch was again negative in both second transplants. Two of the four recipients had no detectable antibody to a panel of lymphocytes. Examination of the hearts demonstrated histologic findings consistent with hyperacute rejection. Direct immunofluorescence performed on the transplanted hearts revealed the presence of immunoglobulin and complement deposited on the vascular endothelium. Pathology data was available on 3 of the 4 patients who experienced acute cardiac dysfunction. Pretransplant sera from these four recipients were screened for the presence of antivascular endothelial cell (VEC) antibody. The sera from all four recipients were found to contain antibody against an endothelial cell panel. In addition, donor-specific aorta and vena cava were available from one of the heart donors. The recipient was found to have donor-specific antibody to VEC. Thus, antibody directed against VEC specific antigens appears to be related to hyperacute rejection of heart allografts.

Antibodies↗
PubMed1985

Molecular cloning and physical mapping of the tupaia herpesvirus genome.

Purified virion DNA of about 200 kilobase pairs of tupaia herpesvirus strain 2 was cleaved with EcoRI or HindIII restriction endonuclease. Restriction fragments representing the complete viral genome including both termini were inserted into the EcoRI, HindIII, and EcoRI-HindIII sites of the bacterial plasmid pAT153. Restriction maps for the restriction endonucleases EcoRI and HindIII were constructed with data derived from Southern blot hybridizations of individual viral DNA fragments or cloned DNA fragments which were hybridized to either viral genome fragments or recombinant plasmids. The analysis revealed that the tupaia herpesvirus genome consists of a long unique sequence of 200 kilobase pairs and that inverted repeat DNA sequences of greater than 40 base pairs do not occur, in agreement with previous electron microscopic data. No DNA sequence homology was detectable between the tupaia herpesvirus DNA and the genome of murine cytomegalovirus, which was reported to have a similar structure. In addition, seven individual isolates of tupaia herpesvirus were characterized. The isolates can be grouped into five strains by their DNA cleavage patterns.

Animals↗
PubMed1984

The inner arm fasciocutaneous flap.

A fasciocutaneous flap raised on the inner surface of the upper arm has been used to release 16 burn scar contractures of the anterior axillary fold. It is a relatively quick and simple procedure that adequately corrects the contracture and does not have to followed by prolonged splinting.

Adolescent↗