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Biomedical subjects

M Jones

Publications and source records attributed to M Jones.

At least 829 records · Page 46Linked to original sources
PubMed1982

Failure of porcine aortic and bovine pericardial prosthetic valves: an experimental investigation in young sheep.

Seventeen porcine aortic and 10 bovine pericardial bioprosthetic valves were implanted in the tricuspid position in 27 young sheep. Clinical, hemodynamic and morphologic evaluations were performed after a mean of 4.7 +/- 0.3 months (range 3-7 months) after implantation. Eight sheep developed ascites (five with porcine aortic and three with bovine pericardial bioprosthetic valves); all 27 sheep had microscopic evidence of hepatic congestion. Three porcine and three bovine valves became infected. Hemodynamic studies (n = 15) performed immediately after implantation and at the time of terminal elective studies showed that tricuspid valve end-diastolic gradients increased from 0.7 +/- 0.4 mm Hg to 4.5 +/- 0.5 mm Hg (p less than 0.01). All 27 valves had calcific deposits. By quantitative analyses, unimplanted cuspal tissue (n = 9) had 0.6 +/- 0.1 mg/g of calcium/g tissue dry weight; explanted porcine aortic valves (n = 16) had 182 +/- 74 and bovine pericardial valves (n = 6) 421 +/- 115 mg/g of calcium/g of tissue dry weight (NS for porcine aortic vs bovine pericardial valves). Morphologic findings were similar in both porcine aortic and bovine pericardial valves, and consisted of calcific deposits, collagen degeneration, microthrombi and fibrous sheaths. These findings are almost identical to those associated with bioprosthetic valvular failure in humans. In our experimental study, we found no significant differences in the development of calcification in porcine aortic and bovine pericardial bioprosthetic valves.

Animals↗
PubMed1982

Intracuspal hematomas in bioprosthetic valves: pathologic findings and clinical implications.

The presence of intracuspal hematomas (ICHs) was investigated in 156 valvular bioprostheses, including 57 (all porcine aortic valvular bioprostheses) that had been implanted in patients and 99 (64 porcine aortic valvular bioprostheses, 29 bovine pericardial bioprostheses and six human dura mater bioprostheses) that had been implanted in sheep. ICHs were found in three mitral bioprostheses in patients and in 14 porcine aortic valvular bioprostheses (nine mitral and five tricuspid) in sheep. Hematomas were not found in the dura mater or pericardial bioprostheses. In each patient and in six of the 14 sheep, the hematomas involved more than one cusp and consisted of erythrocyte accumulations in the spongiosa. They extended from the basal region toward the free edge of the cusp and formed a plane of dissection that involved the spaces left in the spongiosa by removal of proteoglycan material during commercial processing. ICHs may become sites of formation of calcific deposits. ICHs result from entry of blood into the space between the sewing ring and the most basilar region of the bioprosthetic tissue. This space extends throughout the circumference of the bioprosthesis and is continuous with the spongiosa, the layer in which the hematoma develops. The blood penetrates this space through the suture line between bioprosthetic tissue and sewing ring on the inflow surface of porcine valvular bioprostheses mounted on atrioventricular-type stents. ICHs were not found in porcine valvular bioprostheses mounted on aortic-type stents, in which the sutures are more protected and more closely spaced, on in bioprostheses constructed of tissues (parietal pericardium and dura mater), which lack a spongiosa.

Adolescent↗
PubMed1981

Specific localization of 2',3'-cyclic nucleotide 3'-phosphohydrolase, (Ca2+/Mg2+)-ATPase, and acetylcholinesterase in human erythrocyte membrane.

A procedure was developed for the detection of 2',3'-cyclic nucleotide 3'-phosphohydrolase in myelin. This assay was sufficiently to detect the low levels of 2',3'-cyclic nucleotide 3'-phosphohydrolase in human erythrocytes. The 2',3'-cyclic nucleotide 3'-phosphohydrolase of human erythrocytes was determined to be exclusively associated with the inner (cytosolic) side of the membrane. Leaky ghosts and resealed ghosts were assayed for 2',3'-cyclic nucleotide 3'-phosphohydrolase (Ca2+/Mg2+)-ATPase, and acetylcholinesterase activity, and the 2',3'-cyclic nucleotide 3'-phosphohydrolase profile is the same as that of the (Ca2+/Mg2+)-ATP, an established inner membrane marker.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1981

Screening for metastases in breast cancer: an assessment of biochemical and physical methods.

Ten tumor markers were measured in serum or urine at approximately three month intervals in patients with breast cancer following mastectomy but before development of overt metastatic disease. In 23 patients who later had metastases, only three markers, alkaline phosphatase, carcinoembryonic antigen (CEA), and gamma-glutamyl transpeptidase (gamma-GT) were consistently abnormal prior to the development of detectable metastases in more than one patient. In half the patients, a "lead interval" of three months or more was obtained using these three markers and little advantage was obtained by the addition of any other biochemical marker. The value of these three measurements was then assessed in a larger group of patients and compared with other tests for metastases. Alkaline phosphatase, CEA, gamma-GT, clinical examination, and chest x-ray were the best indices of the metastatic state in breast cancer, being collectively abnormal in 98% of patients at first presentation with metastases. The authors recommend screening patients postoperatively with these five tests for metastases; more detailed tests should only be carried out if results of one or more these are abnormal.

Alkaline Phosphatase↗
PubMed1981

N-Methyl-N'-nitro-N-nitrosoguanidine sensitivity of E. coli mutants deficient in DNA methylation and mismatch repair.

E. coli mutants deficient in DNA methylation (dam) and mismatch repair (mut) have been characterized with respect to their sensitivity to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Dam bacteria are more sensitive than mutH, mutL, and mutS single mutant bacteria. Dam mutL and dam mutS double mutant bacteria are less sensitive than dam bacteria, whereas dam mutH double mutant bacteria are as sensitive as dam bacteria. This pattern of MNNG sensitivity may be a result of the specificity of the components of the E. coli mismatch repair system.

DNA (Cytosine-5-)-Methyltransferases↗
PubMed1981

Changes in peripheral vascular and cardiac sympathetic activity before and after coronary artery bypass surgery: interrelationships with hemodynamic alterations.

The plasma catecholamine levels obtained simultaneously from radial artery (A), pulmonary artery (MV), brachial vein (PV), and coronary sinus (CS) were measured concurrent with hemodynamic determinations during coronary artery bypass graft (CABG) operations. Arterial catecholamine levels decreased after induction of anesthesia and increased after sternotomy; changes in veno-arterial norepinephrine (NE) differences ([PV-A]ne, [MV-A]ne, and [CS-A]ne) were of the same magnitude and direction, suggesting that NE release from various organs was of the same extent. After operation, arterial NE increased further, but the veno-arterial NE differences were in striking contrast; [PV-A]ne became markedly positive, whereas [CS-A]ne became markedly negative, indicating that NE release from extremity peripheral vasculature increased markedly while cardiac NE release decreased. These differential changes in regional sympathetic activity appear to be related to postoperative hypertension (HT) and low cardiac output (CO). There were close relationships of changes in [MV-A]ne to mean arterial pressure (r = 0.78, p less than 0.001) and systemic vascular resistance (r = 0.62, p less than 0.010, suggesting that the sympathetic nervous system plays an important role in CABG perioperative hemodynamic alterations.

Adult↗
PubMed1981

Occurrence and significance of endothelial cells in implanted porcine bioprosthetic valves.

Histologic and scanning and transmission electron microscopic studies were made to determine the frequency of occurrence of endothelial cells in 49 porcine valve bioprostheses removed from 43 patients 2 days to 113 months (average 35 months) after implantation. Endothelial cells were found in none of 17 bioprostheses in place for less than 1 year, in 5 (23 percent) of 22 in place for 1 to 5 years and in 7 (70 percent) of 10 in place for longer than 5 years. The 12 bioprostheses in which endothelial cells were present had been implanted in the atrioventricular position (7 of 32 in the mitral position and 5 of 6 in the tricuspid position) for 21 to 113 months (average 71). Endothelial cells were not found in any of 11 bioprostheses implanted in the semilunar position (9 in the aortic position and 2 in pulmonary conduits); however, all but one of these bioprostheses had been in place for less than 5 years. Endothelial cells were concentrated along the basal regions of the cusps. These cells did not grow in direct contact with valve collagen, but were attached to fibrin, thrombi or fibroelastic host tissue (fibrous sheath) on the valve surfaces. The growth of endothelial cells and associated fibrous tissue may serve to increase the structural stability of bioprosthetic valve cusps, which may be of functional importance several years after implantation when the porcine connective tissue may have undergone significant deterioration.

Adult↗
PubMed1981

Structure and classification of cuspal tears and perforations in porcine bioprosthetic cardiac valves implanted in patients.

Morphologic studies were made of cuspal tears and perforations in 16 porcine valve bioprostheses that had been implanted in 14 patients (9 male and 5 female) ranging in age from 2 to 65 years. Eleven bioprostheses had been in the mitral position for 30 to 123 months, four in the aortic position for 15 to 40 months and one in a varied pulmonary conduit for 96 months. The cuspal lesions were classified into four types. Type I lesions, which involved the free edges of the cusps, were the most common of all lesions and occurred with equal frequency in mitral and aortic bioprostheses. Regardless of position of implantation, type I lesions were more frequent in the right coronary cusp than in the other cusps. Ultrastructural study showed that these lesions develop as consequences of breakdown of collagen at the free edges of the cusps, usually near the commissures. Type II lesions consisted of linear perforations that extended along the basal regions of the cusps, forming an arc parallel to the sewing ring. These lesions were uncommon an resulted from separation of bundles of collagen. Type III lesions, which were large, round or oval perforations that occupied central regions of the cusps, were more common in aortic than in mitral bioprostheses. They were characterized by marked destruction of cuspal tissue and were most frequently associated with infection. Type IV lesions were small pinhole-like perforations; they usually were multiple, localized in central regions of the cusps and associated with calcific deposits. Type IV lesions were more common in mitral than in aortic bioprostheses. Regardless of position, they were more frequent in the left and noncoronary cusps than in the right coronary cusp (which may be protected by its muscle shelf against this type of perforation). It is concluded that cuspal tears and perforations develop in implanted bioprostheses as consequences of structural failure of connective tissue components.

Adolescent↗
PubMed1981

Congenitally bicuspid aortic valve causing severe, pure aortic regurgitation without superimposed infective endocarditis. Analysis of 13 patients requiring aortic valve replacement.

Although stenosis and infective endocarditis are commonly appreciated complications of the congenitally bicuspid aortic valve, pure severe aortic regurgitation complicating this congenital malformation, unassociated with either stenosis or infection, is not well recognized. Among 189 patients who had aortic valve replacement at the National Heart, Lung, and Blood Institute because of isolated pure aortic regurgitation, the congenitally bicuspid aortic valve, never the site of infective endocarditis, was responsible for the aortic regurgitation in 13 (7 percent). This report describes certain clinical and morphologic findings in 13 men, aged 26 to 65 years (mean 43), who required aortic valve replacement because of severe aortic regurgitation secondary to a noninfected, nonstenotic congenitally bicuspid aortic valve. Although not generally recognized, the noninfected congenitally bicuspid aortic valve is an important cause of pure aortic regurgitation severe enough to warrant aortic valve replacement.

Adult↗
PubMed1981

Calcific deposits developing in a bovine pericardial bioprosthetic valve 3 days after implantation.

Calcific deposits, localized in a thin layer of thrombus covering the cuspal surfaces, were present 3 days after implantation in a valved pulmonic conduit that contained an Ionescu-Shiley bovine pericardial valve and was placed in a 29-year-old man with double outlet right ventricle, valvular and infundibular pulmonic stenosis, and ventricular septal defect. Factors that may have contributed to such a rapid calcification were the relatively young age of the patient, the development of acute renal insufficiency postoperatively, and the administration of large amounts of calcium chloride intravenously during blood transfusions and during episodes of cardiac arrest.

Adult↗
PubMed1981

Modified Blalock-Taussig shunt. Use of subclavian artery orifice as flow regulator in prosthetic systemic-pulmonary artery shunts.

Between April, 1975, and December, 1979, 99 modified Blalock-Taussig shunts (MBTSs) were carried out at The Hospital for Sick Children, Great Ormond Street. The operation consists of interposing between the subclavian artery and the pulmonary artery a prosthesis of greater diameter than that of the subclavian artery. The first 13 operations were performed with a prosthesis of woven Dacron. Conduits of expanded polytetrafluorethylene (PTFE) were used for 86 MBTSs, and these form the basis of this report. Forty-four (51.1%) shunts were performed in infancy, 25 in patients under the age of 1 month (29.0%). Prostheses of 4 mm were used in 34 cases, 5 mm in 14, and 6 mm in 38. There were five shunt failures (5.8%) documented at postmortem or angiocardiographic investigation. Including two late deaths for which postmortem examinations were not obtained, the overall failure rate was 8.1% (seven patients). All these patients were operated upon in infancy, four of them in the neonatal period. Although a longer follow-up is necessary to assess the validity of these shunts, the early results are encouraging. We believe we can now recommend MBTS as an alternative when the classical Blalock-Taussig shunt is considered unsuitable.

Blood Vessel Prosthesis↗
PubMed1981

Structure of bovine parietal pericardium and of unimplanted Ionescu-Shiley pericardial valvular bioprostheses.

To obtain a basis for the evaluation of postimplantation changes in bioprostheses made of parietal pericardium, we conducted comparative histologic, scanning and transmission electron microscopic studies of the structure of (1) normal bovine parietal pericardium, (2) glutaraldehyde-treated pericardial patches to be used for repair of cardiac defects, and (3) pericardial tissue cusps of unimplanted Ionescu-Shiley valves. Bovine parietal pericardium has three layers: (1) the serosa, or mesothelial cell layer; (2) the fibrosa, formed by diversely oriented, wavy bundles of collagen and by elastic fibers, and (3) the epipericardial connective tissue layer, which is partly continuous with the pericardiosternal ligaments. Pericardial patches and pericardial bioprosthetic cusps differ from normal pericardium by being denuded of mesothelium but they have normal degrees of waviness in their collagen. In Ionescu-Shiley valves, the inflow and outflow surfaces of each cusp correspond to the epipericardial and serosal surfaces of parietal pericardium, respectively. The inflow surfaces have a coarse texture, characterized by large bundles of collagen, and the outflow surfaces have numerous grooves, 10 to 30 mu in width and 20 mu in depth, which probably result from pressure exerted on the cuspidal surfaces by cotton material either during manufacturing or packing of the valves. Comparisons of the structure of bioprosthetic pericardial cusps and porcine aortic valve cusps show that the latter have reduced degrees of collagen waviness and a different layered structure: A layer similar to the spongiosa of aortic valve cusps is not present in pericardium. The functional implications of these observations are discussed in detail.

Animals↗