An analysis of autopsy findings in 108 patients who died after valve replacement

The pathological findings and the causes of death were reviewed in 108 patients who had received 142 heart valve prostheses (52 mechanical and 90 bioprostheses) at the National Cardiovascular Center in Osaka, Japan, from 1977 to 1991. Rheumatic heart disease was the major underlying disease (60.2%), and the age distribution at death ranged from 21 to 80-year-old. Survival duration after the surgery extended from 0 day to 9 years. Thirty-three patients (30.6%) died of perioperative complications such as myocardial haemorrhage and damage, or from heart failure which had been evident prior to the operation, a cause of death which pre-dominated in patients who died within 1 week of surgery (15/17; 88.2%). Thirty-eight patients (35.2%) died of prostheses-related problems such as prosthetic valve failure (cuspal tears and calcifying destruction of the xenograft), thromboembolism, and prosthetic valve endocarditis. Endocarditis was frequent in patients who had survived longer than 1 year (25/33; 75.8%). None of the patients died of prostheses-related problems within 1 week. Non-infectious valve failure was more common in patients with bioprostheses than in those with mechanical valves; thromboembolism showed the opposite association. Prosthetic valve infective endocarditis was nearly equal in frequency in both types of valve.

Detection of enteroviral genome and its significance in cardiomyopathy

Myocarditis is an important disease that can lead to dilated cardiomyopathy (DCM). Using the polymerase chain reaction (PCR), we examined whether viral genomes were present specifically in the hearts of viral myocarditis or DCM patients in our autopsy series and compared the results with their clinicopathological features. We applied three different criteria of myocarditis to fully describe the histological features. The presence of a viral genome was detected by PCR but was not specific in DCM or myocarditis. PCR might be helpful in the diagnosis of viral myocarditis, when combined with other clinical information.

Structural and functional relationships of human DNA polymerases

A continuing theme of our laboratory has been the understanding of human DNA polymerases at the structural level. We have purified DNA polymerases delta, epsilon and alpha from human placenta. Monoclonal antibodies to these polymerases were isolated and used as tools to study their immunochemical relationships. These studies have shown that while DNA polymerases delta, epsilon and alpha are discrete proteins, they must share common structural features by virtue of the ability of several of our monoclonal antibodies to exhibit cross-reactivity. A second approach we have taken is the molecular cloning of human DNA polymerase delta and epsilon. We have cloned the DNA polymerase delta cDNA, and this has allowed us to compare its primary structure to those of human polymerase alpha and other members of this polymerase family. Multiple sequence alignments have revealed that human DNA polymerase delta is also closely related to the herpes virus family of DNA polymerases. In situ hybridization has shown that the human DNA polymerase delta gene is localized to chromosome 19 q13.3-q13.4. In order to further determine the functional regions of the DNA polymerase delta structure we are currently expressing human pol delta in E. coli and baculovirus systems. Other work in our laboratory is directed toward examining the expression of DNA polymerase delta during the cell cycle.

N omega-nitro-L-arginine blocks the second phase but not the first phase of the endothelium-dependent relaxations induced by substance P in isolated rings of pig carotid artery

Endothelium-dependent relaxations can be evoked by a variety of stimuli, among them substance P (SP), which is found in sensory nerve fibers supplying the adventitia-media junction of most muscular arteries. This study determined the role of endothelium-derived nitric oxide as a mediator of endothelium-dependent relaxations to SP in isolated rings of the pig carotid artery suspended in organ chambers for isometric tension recording. SP (10(-12)-10(-7) M) caused concentration-dependent relaxations of arteries precontracted with norepinephrine (10(-7) M). The relaxations were characterized by a partially transient relaxation (phase 1) and a sustained relaxation of the artery (phase 2). The inhibitor of nitric oxide formation, N omega-nitro-L-arginine (L-NNA) methyl ester caused a gradual increase in tension, the phase I response at 3 x 10(-10) to 3 x 10(-7) M SP was shifted to the right, but the maximal relaxation was comparable in the presence of L-NNA. However, the sustained relaxation after addition of substance P (phase II) was lost and tension in the presence of L-NNA returned to a level above that induced by L-NNA and norepinephrine (10(-9) M). These results suggest that the endothelium-dependent relaxations to SP, particularly the prolonged relaxation (phase II), are due to de novo synthesis of nitric oxide and hence fully abolished by a specific inhibitor.

Molecular cloning of the cDNA for the catalytic subunit of human DNA polymerase delta

The cDNA of human DNA polymerase delta was cloned. The cDNA had a length of 3.5 kb and encoded a protein of 1107 amino acid residues with a calculated molecular mass of 124 kDa. Northern blot analysis showed that the cDNA hybridized to a mRNA of 3.4 kb. Monoclonal and polyclonal antibodies to the C-terminal 20 residues specifically immunoblotted the human pol delta catalytic polypeptide. A multiple sequence alignment was constructed. This showed that human pol delta is closely related to yeast pol delta and the herpes virus DNA polymerases. The levels of pol delta message were found to be induced concomitantly with DNA pol delta activity and DNA synthesis in serum restimulated proliferating IMR90 cultured cells. The human pol delta gene was localized to chromosome 19 by Southern blotting of EcoRI digested DNA from a panel of rodent/human cell hybrids.