Three spontaneous H-2Db mutants are generated by genetic micro-recombination (gene conversion) events. Impact on the H-2-restricted immune responsiveness.

Sequence analysis of the mutant Dbm13, Dbm14, and Dbm24 genes indicate that they differ from the parental Db gene by 4, 1, and 8 nucleotides, respectively. The mutant sequences substituted into Dbm13 and Dbm24 are identical to those found in the Kb gene, at the homologous positions. Thus, similar to the Kb gene, the Db gene is able to undergo micro-recombination (gene conversion) events with other class I genes. Such data suggest that micro-recombination events could be an important mechanism for the diversification of all H-2 genes. The Db mutant products share a common theme: the alterations in all occur at amino acid residues whose side chains in the homologous class I HLA-A2 molecule project into the postulated peptide antigen-binding cleft, and hence, would be expected to alter the binding of foreign or self peptides. Due to such changes, the bm14 mouse has become a nonresponder in the CTL response to Moloney murine leukemia virus (M-MuLV), as the alteration of one amino acid residue at position 70 (a Gln to His) is sufficient to entirely abrogate the cell-mediated response to the virus. On the other hand, the bm13 mouse has shifted the major part of its M-MuLV restriction to Kb, a profound alteration in CTL responsiveness due to the alteration of three amino acids (Leu to Gln at 114, Phe to Tyr at 116, and Glu to Asp at 119) in a peptide stretch of beta-pleated sheet structure lining the bottom of the antigen-binding cleft. Thus, study of these mutants reveals that, in one step, micro-recombination at the genetic level has resulted at the protein level in profound changes in the immune response to viral infection. Such a mechanism operating at the population level can be a driving force during evolution for modulating the character of CTL immunity.

Reduction in susceptibility to natural killer cell-mediated lysis of human FO-1 melanoma cells after induction of HLA class I antigen expression by transfection with B2m gene.

Induction of HLA class I antigens on cultured melanoma cells FO-1 after transfection with a human or a mouse B2m gene was associated with a statistically significant reduction in their susceptibility to natural killer (NK) cell-mediated lysis. These results indicate that the structural differences between human and mouse beta 2-mu do not abolish the ability of the HLA class I molecular complex to modulate NK cell-mediated lysis of melanoma cells FO-1. The role of HLA class I antigens in the phenomenon is corroborated by the ability of anti-HLA class I MAb to enhance, although to a different extent, the susceptibility of transfected FO-1 cells to NK cell-mediated lysis. Gamma interferon (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) significantly reduced the susceptibility to NK cell-mediated lysis of transfected FO-1 cells. Surprisingly, TNF-alpha reduced the extent of lysis more than IFN-gamma, although the latter cytokine enhanced HLA class I antigen expression more than the former one. This finding, in conjunction with a reduction in the susceptibility to NK cell-mediated lysis of untransfected FO-1 cells incubated with IFN-gamma or TNF-alpha, suggests that the two cytokines reduce NK cell-mediated lysis of transfected cells by modulating not only the expression of HLA class I antigens, but also that of other structures. Induction of HLA class I antigens and their modulation with IFN-gamma did not affect the susceptibility to lymphokine-activated killer (LAK) cell-mediated lysis of transfected FO-1 cells. Characterization of the molecular mechanism(s) underlying abnormalities in HLA class I antigen expression by melanoma cells and of the role of these molecules in the interactions of melanoma cells with various types of effector cells may suggest novel immunotherapeutic approaches to melanoma.

Lack of HLA class I antigen expression by cultured melanoma cells FO-1 due to a defect in B2m gene expression.

The melanoma cell line FO-1 does not express HLA class I antigens and does not acquire them on the cell surface after incubation with IFN-gamma. Immunochemical studies showed that FO-1 cells synthesize HLA class I heavy chain, but do not synthesize beta 2-microglobulin (beta 2-mu). The latter abnormality is associated with lack of beta 2-mu mRNA which remains undetectable in FO-1 cells incubated with IFN-gamma. The defect was identified as a genetic lesion in the B2m gene, since DNA hybridization analysis detected a deletion of the first exon of the 5'-flanking region, and of a segment of the first intron of the B2m gene. HLA class I antigen expression was reconstituted on melanoma cells FO-1 after transfection with the wild-type mouse B2m gene, thereby confirming the abnormality of the endogenous B2m gene. The defect identified in FO-1 cells is distinct from that underlying the lack of HLA class I antigen expression by lymphoblastoid cells Daudi, but is remarkably similar to that causing lack of H-2 class I antigen expression by mouse lymphoblastoid cells R1 (TL-). These results suggest that genetic recombination in the 5' region of the B2m gene is a recurrent mechanism in B2m gene defects. In addition to contributing to our understanding of molecular abnormalities in HLA class I antigen expression by melanoma cells, FO-1 cells represent a useful model for analyzing the role of HLA class I antigens in the biology of melanoma cells and in their interaction with cells of the immune system.

Lack of HLA class I antigen expression by melanoma cells SK-MEL-33 caused by a reading frameshift in beta 2-microglobulin messenger RNA.

The lack of HLA class I antigen expression by the melanoma cell line SK-MEL-33 is caused by a unique lesion in beta 2-microglobulin (beta 2-mu). Sequencing of beta 2-mu mRNA detected a guanosine deletion at position 323 in codon 76 that causes a frameshift with a subsequent introduction of a stop codon at a position 54 base upstream of the normal position of the stop codon in the message. The loss of 18 amino acids and the change of 6 amino acids, including a cysteine at position 80 in the carboxy terminus of beta 2-mu, are likely to cause marked changes in the structure of the polypeptide. The latter may account for the inability of beta 2-mu to associate with HLA class I heavy chains and for its lack of reactivity with the anti-beta 2-mu mAb tested. HLA class I antigen expression on SK-MEL-33 cells was reconstituted after transfection with a wild-type B2m gene, therefore indicating that the abnormality of endogenous B2m gene is the only mechanism underlying lack of HLA class I antigen expression by SK-MEL-33 cells. The guanosine deletion in B2m gene was detected also in the melanoma tissue from which SK-MEL-33 cells had originated. Therefore, the molecular lesion identified in the SK-MEL-33 melanoma cell line is not caused by a mutation acquired during growth in vitro but is likely to reflect a somatic mutation during tumor progression.

Interaction between Kb and Q4 gene sequences generates the Kbm6 mutation.

Genetic interaction as a mechanism for the generation of mutations is suggested by recurrent, multiple nucleotide substitutions that are identical to nucleotide sequences elsewhere in the genome. We have sequenced the mutant K gene from the bm6 mouse, which is one of a series of eight closely related, yet independently occurring mutants known collectively as the "bg series." Two changes from the Kb gene are found, positioned 15 nucleotides apart: an A-to-T change and a T-to-C change in the codons corresponding to amino acids 116 and 121, resulting in Tyr-to-Phe and Cys-to-Arg substitutions, respectively. Hybridization analysis with an oligonucleotide specific for the altered Kbm6 sequence identifies one donor gene, Q4, located in the Qa region of the H-2 complex. The two altered nucleotides that differentiate Kbm6 and Kb are present in Q4 in a region where Kb and Q4 are otherwise identical for 95 nucleotides, delineating the maximum genetic transfer between the two genes. Because the Kbm6 mutation arose in an homozygous mouse these data indicate that the Q4 gene contains the only donor sequence and demonstrates that Q-region gene sequences can interact with the Kb gene to generate variant K molecules.

Differential effect of human and mouse beta 2-microglobulin on the induction and the antigenic profile of endogenous HLA-A and -B antigens synthesized by beta 2-microglobulin gene-null FO-1 melanoma cells.

beta 2-Microglobulin (beta 2-mu) gene-null human melanoma FO-1 cells display lower reactivity with anti-HLA class I monoclonal antibodies (mAb) following transfection with a wild-type mouse beta 2-mu gene (referred to as FO-1C cells) than following transfection with a wild-type human beta 2-mu gene (referred to as FO-1H cells). Furthermore, binding assays with a panel of anti-HLA class I mAb detected higher reactivity of FO-1C cells with mAb TP25.99 than with mAb CR1-S63, CR10-215, CR11-115, TP67, and W6/32 but similar reactivity of FO-1H cells with all the mAb tested. While mAb TP25.99 recognizes a determinant expressed on beta 2-mu-free and beta 2-mu-associated HLA class I heavy chains, the remaining mAb recognize determinants expressed only on beta 2-mu-associated HLA class I heavy chains. The differential effects of mouse and human beta 2-mu on the reactivity with anti-HLA class I mAb of FO-1 cells reflect more than one mechanism. Besides abnormalities in the processing of HLA class I heavy chains associated with mouse beta 2-mu, this molecular complex appears to be unstable on the plasma membrane of FO-1 cells. To analyze the interaction of mouse beta 2-mu with HLA-A and -B antigens, the HLA phenotype of FO-1 cells was determined, using a combination of isoelectric focusing analysis of antigens immunoprecipitated from radiolabeled cells with mAb to monomorphic determinants of HLA class I antigens, binding assays with a limited number of mAb recognizing HLA class I allospecificities, and sequence-specific oligonucleotide probe typing. Although association with mouse beta 2-mu does not cause marked differences in the expression of HLA-A25 and -B8 antigens on the cell surface of FO-1 cells, it causes a selective reduction in the expression of determinants recognized by anti-HLA-A mAb F4/72 and VF19-LL67 and by anti-HLA class I mAb W6/32 on HLA-A25 allospecificities. The differential effect of the association with mouse beta 2-mu on the antigenic profile of HLA-A25 and -B8 antigens may reflect the different characteristics of the amino acids at residue 12, which interact with residue 33 of beta 2-mu. The latter residue is the only one to differ between human and mouse beta 2-mu in the stretch of amino acids interacting with the alpha 1 and alpha 2 domains of HLA class I heavy chains.(ABSTRACT TRUNCATED AT 400 WORDS)

Failure in expression of structurally altered (CYS164-->TYR) H-2Kb molecules is mitigated with high affinity peptide-ligand.

A C164Y somatic mutation in the H-2Kb class I molecule causes a disruption of the alpha 2 domain disulfide bond and results in a loss of H-2Kb cell surface expression by the 69.9.15 cell line. In vitro culture of the somatic cell variant at 30 degrees C induced weak, but reproducible, expression of the H-2Kb mutant molecule on the cell surface, which suggests that a temperature-sensitive mutation was contributing to the H-2Kb null phenotype. Based on the inherent structural instability of the mutant H-2Kb molecules synthesized by 69.9.15 cells, we sought to determine the ability of high affinity peptide-ligand to counteract the null expression of H-2Kb. Treatment of 69.9.15 cells was performed with acid-eluted cell-derived peptides, as well as synthetic H-2Kb-restricted peptides, ovalbumin (OVA) p257-264 (YSIINFEKL), and vesicular stomatitis virus-nuclear protein p52-59 (RGYVYQGL). Whereas the endogenous and vesicular stomatitis virus peptides were ineffective at inducing H-2Kb expression at either 37 degrees C or 30 degrees C, treatment with the OVA peptide at 30 degrees C gave rise to dose-dependent enhancement in H-2Kb expression, an effect that was independent of exogenous sources of bovine beta 2-microglobulin at the time of peptide treatment. By comparison, expression of H-2Kb remained unaltered when cells were treated with the OVA peptide at 37 degrees C, consistent with the temperature-sensitive expression of the mutant molecules. Decay of H-2Kb from the cell surface was similar for both 69.9.15 and RMA-S cells, an indication that binding of OVA p257-264 provided the same level of stability for class I molecules with either a cis-(69.9.15) or trans-acting (RMA-S) defect in heavy chain transport. These data provide novel evidence that transport-defective MHC class I molecules, similar in nature to those encoded by class I genes isolated from human genomic libraries, i.e., the 12.4 pseudogene with a polymorphism at amino acid position 164 (C-->F), are subject to high affinity peptide-induced stabilization which reverses the class I null phenotype.

Mutants of human beta2-microglobulin map an immunodominant epitope within the three-stranded beta-pleated sheet.

Genetically engineered structural variants of human beta2-microglobulin (beta2m) were produced by sequence exchange with mouse beta2m for the purpose of examining species-specific antigenic determinant expression. For aggregate mapping, mouse and human beta2m, which differ by 30% in their primary sequence of 99 amino acids, were prepared as chimeric (human X mouse) molecules and expressed in the FO-1 beta2m-null human melanoma cell line. A chimera containing residues 1-69 from human beta2m (and residues 70-99 from mouse beta2m) induced expression of the epitopes defined by the anti-beta2m monoclonal antibodies (mAb) BBM.1, NAMB-1, and L368; the reverse chimera did not, although HLA class I heavy chain was evident on the cell surface as determined with the TP25.99 mAb. For fine dissection of the epitopes defined by these mAbs, site-directed mutants of beta2m were prepared by replacement of individual amino acids in human beta2m with the dimorphic residue from mouse beta2m. Substitutions were made at each divergent residue between positions 1 and 66 and, as controls for COOH-terminal modification, a series of residues between positions 75 and 94. Replacement of amino acids 38, 44, and 45, but not 16 other dimorphic residues in the linear stretch from residue 1 to residue 66, resulted in the loss of, or gross reduction in, binding by mAbs BBM.1 and NAMB-1. A reduction in binding was also observed for mAb L368. These data provide strong evidence that the antigenic epitopes defined by these mAb map to a region including S3 and its adjacent intra-beta-strand turn of the three-stranded beta-pleated sheet of beta2m. The mapping of these epitopes is consistent with their accessibility in the assembled major histocompatibility complex class I molecule and indicates that the region from amino acid 38 to 45 is an important structural feature in the "foreignness" of human and mouse beta2m.

The role of beta-2 microglobulin in temperature-sensitive and interferon-gamma-induced exocytosis of HLA class I molecules.

The passage of MHC class I heavy chains through the exocytic pathway is promoted by association with beta 2 microglobulin (beta 2m). In order to analyze the structural basis of this phenomenon, processing and cell surface expression of HLA class I molecules have been investigated in the beta 2m null human melanoma cell line FO-1 transfected with either the human or mouse beta 2m genes. These natural structural variants of beta 2m display 30% amino acid sequence divergence. In comparison with a human beta 2m transfectant of the FO-1 cell line (designated FO-1H), FO-1 cells transfected with the mouse beta 2m gene (FO-1C) express HLA class I molecules that are processed with grossly altered kinetics and are present on the cell surface at reduced levels. The suboptimal expression of HLA class I heavy chains encoded by FO-1C cells reflects a defect in heavy chain stability since cell surface expression of HLA class I antigens was increased following incubation at 30 degrees C. The increased cell surface expression paralleled accelerated processing of HLA class I heavy chains by FO-1C cells. In contrast, no induction in either cell surface expression or processing of HLA class I heavy chains was observed for the beta 2m-negative FO-1 parent cell line, which remained HLA class I antigen null when cultured at 30 degrees C, or the FO-1H human beta 2m transfectant, which expressed equivalent levels of HLA class I antigens on the cell surface at 37 degrees C and 30 degrees C. Further up-regulation of the temperature-sensitive induction of HLA class I antigen expression was accomplished by treatment of the FO-1C transfectant with interferon-gamma; this latter effect appears to be active at a posttranscriptional step for FO-1 cells since IFN-gamma was not as potent a transcriptional activator at 30 degrees C as it was at 37 degrees C. These results indicate that HLA class I heavy chains expressed by FO-1C cells are subject to temperature-sensitive and cytokine-inducible stabilization that increases their affinity for the structural variant of beta 2m and promotes exocytosis of the HLA class I heterodimer to the cell surface. Furthermore, beta 2m non-conformed MHC class I heavy chains undergo stabilization that is not associated with enhanced cell surface expression, indicating that the exocytosis of putative "empty" HLA class I antigens is a process dependent upon association with beta 2m.

MHC class I heavy chain-dependent expression of discontinuous antigenic epitopes on beta 2-microglobulinb is inducible with peptide-ligand.

Previously, we reported that expression of the murine beta 2-microglobulinb (beta 2mb) antigenic epitopes defined by the mAb S19.8 and 23 (SJL [beta 2ma] anti-B10.S beta 2mb]) was dependent upon association of beta 2m with MHC class I heavy chains. We have further explored the antigenic properties of beta 2m under circumstances requiring the induction of MHC class I surface expression with heavy chain-specific peptide-ligand. For the RMA-S cell line, which is class I surface null due to a defect in the TAP-2 peptide transporter, treatment with the H-2Kb-specific vesicular stomatitis virus-derived N p52-59 peptide resulted in the cell surface expression of the epitopes defined by the anti-H-2Kb mAb Y-3, as well as equally strong expression of the epitopes defined by the anti-beta 2mb mAb S19.8 and 23. Similarly, the FLU-NP p366-374 peptide induced H-2Db on the surface of RMA-S cells as determined by cytofluorometry with the mAb MKQ8; however, expression of the epitope defined by S19.8 was only partially recovered and no reactivity was observed for mAb 23. That the H-2Db heavy chain was assembled with beta 2mb on the cell surface was established from immunoprecipitation experiments with 125I-surface-radiolabeled RMA-S cells treated with FLU-NP p366-374; MKQ8 immunoprecipitated prominent heavy chain and beta 2m bands, whereas S19.8 and 23 isolated a weak beta 2m band (12-15% of that co-immunoprecipitated with MKQ8). These results are consistent with the observation that human beta 2m-deficient cells (designated FO-1) transfected with the B2mb allele were induced, in combination with the endogenous HLA class I heavy chains, to express the epitope defined by S19.8, but not mAb 23, whereas both were expressed when contransfection was performed with the H-2Kb gene. That the determinants recognized by S19.8 and 23 were formed by a discontinuous cluster of amino acids within beta 2m was established from experiments demonstrating that H-2Kb heavy chain assembled with a chimeric beta 2m molecule (comprising human beta 2m from 1-69 and mouse beta 2m from amino acid 70-99, including the polymorphic residue Ala 85) did not lead to expression of the S19.8 and 23 epitopes. The results of this study provide evidence that heavy chain polymorphism can affect the antigenic properties of beta 2m and offer insight into the basis by which CTL may react against beta 2mb when assembled with the H-2Kb molecule.

Failure of cell surface expression of a class I major histocompatibility antigen caused by somatic point mutation.

The ability to down-regulate major histocompatibility complex class I antigen expression on allografts prior to transplantation would be expected to improve their survival in immunocompetent recipients. In order to identify genetic mechanisms that mediate attenuation of MHC class I antigen expression, we have begun characterizing H-2Kb surface null somatic cell variants derived from an H-2 heterozygous tumor cell line (H-2b X H-2d). These variants have sustained a modification in cell surface MHC phenotype, as evidenced by their failure to be recognized by both anti-H-2Kb antibodies and cytotoxic T lymphocytes. The mutant phenotype for one such variant (designated 69.9.15) was marked by the expression of abundant H-2Kb mRNA and immuno-precipitable H-2Kb protein in cell lysates. The failure in cell surface expression of the H-2Kb antigen was caused by a single base change (G to A transition) in exon 3, encoding the second external domain (alpha 2) of the H-2Kb molecule. The mutation resulted in the substitution of Tyr for Cys at amino acid position 164, thereby disrupting an intrachain disulfide linkage formed between Cys 101 and 164. In contrast to the wild-type H-2Kb gene, DNA-mediated transfer of the mutant H-2Kb gene into mouse L cell fibroblasts failed to result in cell surface expression of the H-2Kb antigen, although both the wild-type and mutant genes were transcribed to equivalent levels. These data indicate that a genetic event as limited as somatic point mutation can abrogate expression of a MHC class I antigen and provide support for the hypothesis that protein folding plays an important role in the cell surface expression of MHC class I molecules.

Tissue factor expression in human leukocytes and tumor cells.

Tissue factor (TF) exists in a cryptic form [i.e. without procoagulant activity (PCA)] in peripheral blood monocytes and quiescent tissue macrophages but is expressed constitutively in most human tumor cells. Induction and cell surface expression of TF in these cells in vivo is associated with activation of intravascular and extravascular coagulation in patients with a variety of inflammatory or malignant diseases. The regulation of TF synthesis in cells is complex and new information from transfection studies suggests that changes in cellular glycosylation pathways impair cell surface expression of functional TF. Such dysregulation may also characterize the lineage-unfaithful expression of TF in leukemic cells and perhaps explain some of the thrombohemorrhagic complications in patients with acute progranulocytic leukemia. The importance of carbohydrate modification of TF is reviewed.

Tissue factor expression in human leukemic cells.

Patients with acute leukemia are at increased risk for thrombotic and hemorrhagic complications, particularly those patients with acute promyelocytic leukemia (APL) undergoing induction chemotherapy. These serious complications have been attributed by some authors to the release of tissue factor (TF) procoagulant activity (PCA), particularly during cytotoxic chemotherapy. In previous studies of normal peripheral blood cells, only cells of the monocyte lineage have been found to express TF PCA. Therefore, several questions remain regarding the origin and characterization of the PCA in malignant leukemic cells, particularly those thought to be derived from granulocyte progenitor cells. We utilized a full-length cDNA probe, several monoclonal antibodies (MAbs) and a sensitive one-stage PCA assay to study the expression of TF in the human cell line, HL-60, in human peripheral blood monocytes/macrophages (Mo/Mø) and in highly purified populations of human polymorphonuclear leukocytes (PMN). In the HL-60 cells we detected low but significant levels of TF mRNA and TF antigen (TF:Ag). In unstimulated cells, coordinate increased levels of TF mRNA, TF:Ag and TF PCA expression were noted following phorbol-ester-induced macrophage differentiation of the cells, but a decreased level of TF mRNA with no change in the basal level of TF:Ag expression occurred following retinoic acid-induced granulocyte differentiation of this cell line. Long-term cultures of stimulated mature Mo/Mø demonstrated initial coordinate expression of TF mRNA, TF:Ag and TF PCA, but TF:Ag expression persisted even after 7 days (when TF PCA was undetectable). No TF PCA, TF:Ag or TF mRNA was demonstrated in highly purified populations of human PMN, regardless of culture conditions. Discordant expression of TF mRNA, TF:Ag and TF PCA in HL-60 cells suggests the possibility of novel, post-synthetic mechanisms for the regulation of TF PCA expression, which might be dependent on the phenotypic differentiation level of the cell. Such mechanisms (yet to be defined) might account for the ability of some leukemic cells, which frequently express characteristics of more than one cell line (e.g. monocytes and granulocytes), to express a TF gene product capable of activating blood coagulation.

Emergency coronary artery reperfusion: a choice therapy for evolving myocardial infarction. Results in 339 patients.

Between 1975 and 1982, 339 patients underwent emergency coronary artery reperfusion for treatment of evolving myocardial infarction (MI). Group I (112 patients) had reperfusion with intracoronary streptokinase. Group II (46 patients) had reperfusion with a combination of intracoronary streptokinase and percutaneous transluminal coronary angioplasty (PTCA). Group III (181 patients) had saphenous vein bypass grafting. Twenty Group I patients and one Group II patient had emergency bypass grafting as streptokinase and PTCA were unsuccessful and significant myocardium remained at risk due to residual stenosis in the MI artery. Seventy-nine percent of Group III patients had successful thrombectomy of the infarcted artery, 33% of Group I had significant residual lesions after clot lysis, and 16% of Group I and 17% of Group III patients had no observable lesion on restudy. There were 10 early and two late deaths in the surgical patients. There were two deaths in Group I and no deaths in Group II. All deaths occurred in patients who were in cardiogenic shock before reperfusion (Group IV). Late follow-up (220 patients to 78 months) revealed three late MIs, four cerebral vascular accidents, two late cardiac and three noncardiac late deaths, and 31 patients with residual symptoms. Patients with an emerging MI should be treated via reperfusion of the MI vessel by one of these techniques. With single-vessel involvement, streptokinase lysis of the intercoronary thrombosis should be attempted. If this is successful and there is a significant residual stenotic lesion, the vessel should undergo balloon angioplasty at that time. If PTCA is unsuccessful, then bypass grafting should be done. When significant multiple-vessel disease exists in conjunction with an acute MI, the patient should have emergency saphenous vein bypass grafting as the treatment of choice.

Immediate coronary bypass following failed streptokinase infusion in evolving myocardial infarction.

Since December of 1980, 184 patients with evolving myocardial infarction (EMI) have undergone streptokinase infusion, with associated percutaneous transluminal coronary angioplasty (PTCA) in 68 patients. Emergency coronary bypass was deemed necessary in 24 of these patients. All 24 patients had severe triple-vessel disease and moderate to marked ventricular dysfunction, with eight (33%) requiring intra-aortic balloon pump (IABP) support for profound cardiac decompensation preoperatively. All 24 patients underwent immediate coronary bypass (average 4.1 grafts/patient), with four operative and two late deaths. Average postoperative blood loss was 1,453 ml, and average blood transfusion postoperatively was 8.2 units per patient. Thirteen patients had normal clotting studies immediately postoperatively, and only two patients developed frank coagulopathy (hyperfibrinolysis). Four patients required reexploration; two for coagulopathy, one for surgical bleeding, and one to rule out tamponade (negative). In those patients with EMI in whom streptokinase fails to result in adequate reperfusion, immediate emergency saphenous vein bypass grafting may be performed with reasonable morbidity and with acceptable hematologic consequences.

Influence of primary closure of the pericardium after open-heart surgery on the frequency of tamponade, postcardiotomy syndrome, and pulmonary complications.

Experiences with primary closure of the pericardium in a series of 100 patients undergoing open-heart operations are described. The pericardium was kept under tension during the operation to minimize shrinkage and permit closure at the end of the procedure. In 28 patients one pleural space was opened for drainage, whereas in 72 patients intra- and extrapericardial sumps alone were used for drainage. Measurements of sump drainage revealed that most postoperative bleeding originates from outside the pericardium. There were no instances of cardiac tamponade although 19 patients lost more than 1 L. of blood after operation and 5 required reoperation for hemorrhage. Transpleural drainage tubes were shown to be ineffective and in addition were associated with a fourfold increase in postcardiotomy syndrome and a significantly greater frequency of pleural effusion and atelectasis when compared to the use of mediastinal sump drainage alone. We have concluded that closing the pericardium and using mediastinal sump drainage minimizes the risk of cardiac tamponade and allows early localization of the site of postoperative bledding. Another advantage of pericardial closure and drainage is that postoperative adhesions and postcardiotomy syndrome will be less significant. As a consequence the danger of injuring the heart in a subsequent operation is lessened.

Inflammatory epicardial reaction to processed bovine pericardium: case report.

Processed bovine pericardium is increasingly used as a pericardial substitute. It is allegedly nonreactive with epicardium, but adequate clinical data are lacking on this subject. A case report is presented wherein a dense epicardial reaction to processed bovine pericardium was found at reoperation. Histologic examination confirmed the presence of a severe inflammatory response.

Sternal and costochondral infections following open-heart surgery. A review of 2,594 cases.

From a series of 2,594 patients undergoing open-heart surgery, 39 had sternal or costochondral infections. Most of these infections were associated with a number of predisposing factors: prolonged perfusion time, excessive postoperative bleeding, depressed cardiac output in the postoperative period, and a history of re-exploration for the control of hemorrhage. One important factor was the use of bilateral internal mammary artery implants. The prognosis for patients with sternal wound infections appears related to the length of time required for institution of treatment and the adequacy of initial therapy. Most of these infections are caused by staphylococcus, although the more complicated infections often are caused by fungus. The prevention of serious sternal infections depends on a combination of proper preoperative preparation, attention to minute details at the time of operation, and recognition of variables predisposing to wound complications.

A newly designed arterial monitoring/perfusion cannula for cardiac operations.

A newly designed arterial monitoring and perfusion cannula for cardiopulmonary bypass eliminates the need for cannulation of a peripheral artery for pressure monitoring. The double-lumen cannula is designed as follows: the large central lumen (12 to 26f) acts as the arterial inflow conduit from the pump oxygenator, while a second, smaller lumen (18 gauge)constructed in the wall of the first cannula acts as the pressure-monitoring port and the source for blood sampling and drug infusion. This monitoring/perfusion cannula has been used succesfully in more than 250 clinical patients in a variety of settings--total cardiopulmonary bypass, left heart bypass, and when multiple arterial inflow lines were necessary (as in aortic arch replacement). Use of this cannula is advantageous in the infant and pediatric patient or in the emergency setting, when insertion of a peripheral arterial line can be difficult. Used in conjunction with a Doppler system, the cannula provides accurate, dependable blood pressure monitoring.

Reperfusion protocol and results in 738 patients with evolving myocardial infarction.

Reperfusion is an accepted therapy for evolving myocardial infarction (MI), as successful reperfusion reduces morbidity and mortality. A team approach between the cardiologists and cardiac surgeons must be applied to achieve reperfusion within a finite time from the onset of coronary thrombosis. Analysis of 738 patients grouped them by successful reperfusion in the catheterization laboratory versus the operating room. Factors that predict wall motion recovery related to the onset of clinical symptoms, time to reperfusion, coronary anatomy, and collateral network were reviewed. Comparisons were made between patients with stable versus unstable hemodynamics and successful or unsuccessful reperfusion. Of the 738 patients, the initial attempt at reperfusion was made in the catheterization laboratory with success in 331. These patients all had primarily single-vessel disease. With multiple-vessel disease identified at catheterization, 189 patients were immediately treated by surgical reperfusion. This method also was used for an additional 72 patients in whom reperfusion could not be achieved in the catheterization laboratory. Of the entire group of 738 patients, 146 (20%) could not be reperfused. Overall mortality for the 592 patients reperfused was 4.9% compared with 17% for those who could not be reperfused. Time was critical for wall motion recovery if no collaterals were demonstrated on angiography. If collaterals were present, time to reperfusion was not critical. Wall motion recovered in 90% of the patients if the endocardial anatomy on the initial angiogram was smooth. However, if the endocardial anatomy looked mottled and irregular, less than 10% of patients had recovery of wall motion.(ABSTRACT TRUNCATED AT 250 WORDS)