Chronic ulcerated plaques: new insights into the pathogenesis of acute coronary disease.

Ulcerated atherosclerotic plaques form the substrate for the vast majority of coronary thrombi, but this association does not prove that either one or both of these lesions represents a recent development. Recent reports suggest ulcerated plaques may exist for weeks, months, and possibly years without resolving and reestablishing endothelial integrity. The coronary arteries of 83 patients dying of acute coronary disease were extensively examined, histologically, to determine the pathologic features associated with ulcerated plaques but not associated with an intraluminal thrombus. These findings were then correlated with the degree of luminal stenosis, the presence of inflammatory cell infiltrates, calcification, and necrotic atherosclerotic plaques. The results show ulcerated plaques without thrombosis are ubiquitous, multiple, are unrelated to the degree of luminal stenosis, and are consistently associated with inflammatory cell infiltrates, calcification, and necrotic plaques. Our observations suggest acute coronary disease may result from thrombosis and possibly other biochemical reactions, superimposed on chronic, rather than on recent, ulcerated plaques that have been present for an indeterminate length of time before the onset of acute symptoms. These observations form the basis for an alternative approach to the understanding of the pathogenesis of acute coronary disease and have implications for the prevention of thrombosis.

Streptokinase in the treatment of an acute cerebral embolus--a case report.

During cerebral angiographic examination of a sixty-five-year-old white male, an acute right hemiplegia resulting from embolic occlusion of the left middle cerebral artery developed. Intravenous streptokinase therapy was initiated within forty-five minutes of symptom onset and the hemiplegia cleared in approximately one hour with no evidence of intracranial hemorrhage. This observation underscores the applicability and potential benefits of immediate intravenous thrombolytic therapy for selected patients presenting with acute cerebral thrombosis or embolism.

Coronary thrombosis and platelet/fibrin microemboli in death associated with acute myocardial infarction.

The frequency and clinical significance of platelet/fibrin microemboli in the microcirculation were investigated in 24 patients whose deaths (before and during hospital admission) were associated with acute myocardial infarction. An acute coronary thrombus was present in all the hearts. In nine hearts an acute thrombus was found in more than one major epicardial coronary artery. A total of 35 acute thrombi were found in the 24 hearts. Platelet/fibrin microemboli were found in 19 (79%) hearts. Eighteen patients died in hospital. The hearts of 16 of these cases showed microemboli; 16 had important arrhythmias or various forms of heart block; 13 showed acute pathological changes in the conduction system. Fourteen of the deaths in hospital were primarily the result of cardiogenic shock and four were primarily caused by arrhythmia. Six of the deaths that occurred before admission to hospital were regarded as being arrhythmic in origin. Three of these showed microemboli and the other three had acute pathological changes in the conduction system. Microemboli were found in two (24%) of 12 control hearts. Coronary thrombosis was found in most deaths caused by acute myocardial infarction and platelet/fibrin microemboli were present in the majority of such hearts. These may arise from the coronary thrombus in the larger upstream vessel supplying the microcirculation.

Long-term follow-up of patients having cardiac catheterization and cardiac operation. Small community hospital results before and after surgery program.

We followed, for a mean period of 67 months, 710 unselected consecutive cases of cardiac catheterization. Catheterizations were done on 298 patients without an in-house cardiac surgery team. When a cardiac operation was required, patients in this group were referred to a distant university medical center and were followed up after 49 and again at 103 months. After the community hospital's surgical team was established, 412 patients were catheterized and follow-up carried out for 45 months. Results show that patients in a community hospital without an in-house cardiac surgery team can be catheterized with low risk, then transferred safely to a distant center for surgical treatment without interim mortality and with good long-term results.

Herpes simplex virus types 1 and 2 homology in the region between 0.58 and 0.68 map units.

The homology between herpes simplex virus type 1 and type 2 (HSV-1 and HSV-2, respectively) DNA between 0.58 and 0.674 map units was compared by Southern and dot blot analysis with DNA of one type of virus as a hybridization probe against the other type. Regions of high homology were interspersed with regions of detectably lower homology. However, only one region (between 0.647 and 0.653 map units) contained few or no homologous sequences. In situ RNA blot hybridization demonstrated that the mRNA species transcribed in the right-hand portion of the region are homologous between HSV-1 and HSV-2, as was previously found for the left-hand portion. A 2.7-kilobase HSV-2 transcript in the right-hand portion of the studied region was clearly that encoding HSV-2 glycoprotein C. Comparative nucleotide sequence analysis of specific regions demonstrated that homologous translational reading frames could be identified in the virus types. This analysis also demonstrated that homology could be abruptly lost outside such reading frames. Comparison of regions of homology with published HSV-1 transcription maps suggests that there can also be large divergence within translational reading frames. Some, but not complete, sequence homology was seen in the putative promoter sequence for the 730-base HSV-1 mRNA mapping to the right of glycoprotein C and the corresponding HSV-2 DNA. This suggests that the rather strict conservation of promoter sequences between homologous HSV-1 and HSV-2 transcripts seen in other regions of the genome may not be a necessary feature between these virus types.

Detailed analysis of the portion of the herpes simplex virus type 1 genome encoding glycoprotein C.

We previously showed that the right third of HindIII fragment L (0.59 to 0.65) of herpes simplex virus type 1 (HSV-1) encodes a family of mRNAs some members of which appear to be related by splicing. In the experiments described in this communication, we determined the nucleotide sequence of the DNA encoding this mRNA family and precisely located the mRNAs associated with this DNA sequence. The major mRNA species is unspliced and encoded by a 2.520-nucleotide region. Just upstream of the 5' end are TATA and CAT box sequences characteristic of HSV-1 promoters. The 3' end maps near a region containing a nominal polyadenylation signal. Three minor species (2,400, 2,200, and 1,900 bases, respectively) appear to share a very short leader sequence with the 5' end of the major mRNA and are then encoded by uninterrupted DNA sequences beginning about 100, 400, and 625 bases downstream of the 5' end of the major unspliced mRNA. These positions map at or very near positions which agree reasonably well with consensus splice acceptor sequences. The fourth mRNA is encoded by a contiguous 730-nucleotide sequence at the 3' end of the major unspliced mRNA and has its 5' end just downstream of recognizable TATA and CAT box sequences. We suggest that this mRNA is controlled by its own promoter. The nucleotide sequence data, in combination with the mRNA localization, demonstrate four potential polypeptides encoded by the region. The largest is 1,569 bases long and defines a 523-amino acid protein with sequence features characteristic of a glycoprotein. This was confirmed to be HSV-1 glycoprotein C by immune precipitation of the in vitro translation product of the major unspliced mRNA, performed with a polyspecific antibody to HSV-1 envelope glycoproteins (anti-env-1 serum), and by comparison of tryptic peptides of this translation product with those of authentic HSV-1 glycoprotein C. Polypeptides encoded by some of the minor species also were tentatively identified.

Detailed characterization of an apparently unspliced beta herpes simplex virus type 1 gene mapping in the interior of another.

We precisely localized the coding region and determined the nucleotide sequence of a 1.2-kilobase beta herpes simplex virus type 1 mRNA which underlies the 3' region of the 5.2-kilobase beta mRNA mapping in HindIII fragment K. This mRNA, which lacks readily detectable splices, has its own promoter by the criteria of identification of putative herpes simplex virus type 1 control sequences and in vitro transcription by a Manley polymerase system.

Herpes simplex virus mRNA species mapping in EcoRI fragment I.

We described the detailed characterization and high-resolution mapping of nine herpes simplex virus type 1 mRNAs encoded in EcoRI fragment I. Four of these mRNAs are partially colinear and encode the same sized polypeptide in vitro. Nucleotide sequence analysis of the DNA around the 5' ends of these mRNAs suggested that the larger may encode a small (ca. 100-dalton) polypeptide not resolvable by in vitro translation.

Uninfected cell polymerase efficiently transcribes early but not late herpes simplex virus type 1 mRNA.

The sequences of the DNAs encoding the 5' ends of one early and one late herpes simplex virus type 1 mRNA were analyzed, and the 5' ends of these mRNA species were precisely located. Neither mRNA species is spliced and the noncoding strand of the DNA contains recognizable T-A-T-A and C-A-T boxes upstream from their respective 5' ends. The early mRNA was efficiently transcribed by a commercially available uninfected cell lysate system, but the late mRNA was not. This difference between early and late mRNAs appears to be general in this virus.

Herpes simplex virus type 1 HindIII fragment L encodes spliced and complementary mRNA species.

We have used DNA bound to cellulose to isolate and translate in vitro herpes simplex virus type 1 (HSV-1) mRNA's encoded by HindIII fragment L (mapping between 0.592 and 0.647), and 8.450-base-pair (8.45-kb) portion of the long unique region of the viral genome. Readily detectable, late mRNA's 2.7 and 1.9 kb in size encoding 69,000- and 58,000-dalton polypeptides, respectively, were isolated. A very minor late mRNA family composed of two colinear forms, one 2.6 kb and one 2.8 kb, was isolated and found to encode only an 85,000-dalton polypeptide. A major early mRNA, 1.8 kb in size encoding a 64,000-dalton polypeptide, was also isolated. High-resolution mapping of these mRNA's by using S1 nuclease and exonuclease VII digestion of hybrids between them and 5' and 3' end-labeled DNA fragments from the region indicated that the major early mRNA contained no detectable splices, and about half of its 3' end was complementary to the 3' region of the very minor 2.6- to 2.8-kb mRNA's encoded on the opposite strand. These mRNA's also contained no detectable splices. The major late 2.7-kb mRNA was found to be a family made up of members with no detectable splices and members with variable-length (100 to 300 bases) segments spliced out very near (ca. 50 to 100 bases) the 5' end.

Detailed characterization of the mRNA mapping in the HindIII fragment K region of the herpes simplex virus type 1 genome.

We have isolated as recombinant DNA clones, in the plasmid pBR322, regions of the herpesvirus type 1 genome spanning the region between 0.53 and 0.6 on the prototypical arrangement. This 11,000-base-pair region corresponds to 10% of the large unique region and encodes five major and several minor mRNA species abundant at different times after infection, which range in length from 7 to 1 kilobase. In this report, we have used RNA transfer blots and S1 nuclease digestion of hybrids between viral DNA and polyribosomal RNA to precisely localize (+/- 0.1 kilobase) these mRNA's. Comparison of neutral and alkaline gels of S1 nuclease-digested hybrids indicates no internal introns in the coding sequences of these mRNA's, although noncontiguous leader sequences near (ca. 0.1 kilobase) the 5' ends of any or all mRNA's could not be excluded. The 5' ends of several late mRNA's that are encoded opposite DNA strands map very close to one another, and the 3' ends of a major late and a major early mRNA, which are partially colinear, terminate in the same region. In vitro translation of the viral mRNA's isolated by hybridization with DNA bound to cellulose and fractionation of mRNA species on denaturing agarose gels allowed us to assign specific polypeptide products to each of the mRNA's characterized. Among other results, it was demonstrated unequivocally that two major late mRNA's, which partially overlap, encode the same polypeptide.

Localization of the site of adenylylation of glutamine synthetase by electron microscopy of an enzyme-antibody complex.

Antibodies to the nucleosidel,N(6)-ethenoadenosine have been used to localize the site of adenylylation of the glutamine synthetase [L-glutamate:ammonia ligase (ADP-forming), EC 6.3.1.2] of Escherichia coli. Antibodies were induced in rabbits by injection of a bovine albumin-ethenoadenosine conjugate. The resulting antisera strongly bound ethenoadenosine, its 5'-nucleotide, or protein conjugates of the nucleoside; little or no crossreaction was seen to adenosine, AMP, or the protein carrier. Ethenoadenylylated glutamine synthetase was prepared by modification of the enzyme by the E. coli adenylyltransferase, using etheno-ATP as a substrate. The ethenoadenylylated glutamine synthetase was precipitated by antibodies to ethenoadenosine in conjunction with goat anti-rabbit gamma globulin. Electron micrographs of reaction mixtures of ethenoadenylylated glutamine synthetase and anti-ethenoadenosine showed individual enzyme molecules complexed with one or more antibodies and pairs of enzyme molecules crosslinked by a single antibody. The approximate site of adenylylation was located from the apparent area of contact between enzyme and antibody. We conclude that the adenylylation sites are on the periphery of the bilayered hexagonal disc, offset by 15 +/- 10 degrees from the 2-fold axis of symmetry through a vertex of the hexagon and 20 +/- 10 A from the plane between the layers of the disc.

Nonobstructive coronary thrombosis in sudden cardiac death.

Careful histologic studies were performed on the coronary arteries, myocardium and conduction system of the hearts of six men aged 32 to 44 years who died suddenly with no history of heart disease. All six hearts demonstrated coronary atherosclerosis without evidence of complete obstruction or myocardial infarction. A nonobstructing mural coronary thrombus was found in all six hearts; in four, the thrombus was located in the left anterior descending coronary artery. Distal microthrombi were found in four hearts. In these six men, the terminal event, often a ventricular arrhythmia, may have been related to the mural coronary thrombus. Small fragments originating from such lesions can obstruct the microcirculation producing sudden lethal arrhythmias. Nonobstructing mural coronary thrombosis may be more prevalent and more significant than previously suspected and should be considered in cases of sudden cardiac death.

Mechanism of the bradycardia during coronary angiography.

Bradycardia occurring during coronary angiography may be due to the direct effect of dye or to reflex vagal effects on pacemaker centers. Fifteen patients were classified according to the origin of the sinus nodal and atrioventricular nodal arteries. In patients with type A anatomy, both the sinus and the atrioventricular nodal arteries arose from the right coronary artery. In those with type B anatomy, only the atrioventricular nodal artery arose from the right coronary artery. Heart rate recordings were made during coronary angiography before and after selective infusion of atropine (0.2mg) into the right coronary artery. In type A patients, the sinus bradycardia observed during right coronary dye injection was caused by a combination of both direct and reflex effects on pacemaker tissue. Sinus bradycardia occurring with left coronary dye injections was entirely reflex in nature and was completely blocked with right coronary arterial injection of atropine. In type B patients, sinus bradycardia with right coronary dye injections was produced by reflex suppression of the sinus pacemaker. A junctional rhythm was consistently produced after administration of atropine. Junctional bradycardia in type B patients was caused by direct suppression of the junctional pacemaker. Thus, angiographic dye appears to decrease heart rate by a direct effect on pacemaker tissue and by reflex vagal suppression of the sinus pacemaker.