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Biomedical subjects

P Allen

Publications and source records attributed to P Allen.

At least 163 records · Page 9Linked to original sources
PubMed1982

Strut fracture and disc embolization of a Björk-Shiley mitral valve prosthesis: localization of embolized disc by computerized axial tomography.

The case of a patient who survived strut fracture and embolization of a Björk-Shiley mitral prosthetic disc is presented. Prompt surgical treatment was directly responsible for survival. In addition, computerized axial tomography of the abdomen aided in localizing and retrieving the embolized disc, which was lodged at the origin of the superior mesenteric artery. A review of similar case reports from the literature supports our conclusions that the development of acute heart failure and absent or muffled prosthetic heart sounds in a patient with a Björk-Shiley prosthetic heart valve inserted prior to 1978 should raise the possibility of valve dysfunction and lead to early reoperation.

Adult↗
PubMed1982

Experience with the Carpentier-Edwards porcine valve prosthesis in 700 patients.

The Carpentier-Edwards porcine valve prosthesis has afforded our patients a satisfactory quality of life and a low incidence of valve-related complications at follow-up periods of up to five years. From December, 1975 to March, 1980, 768 prosthesis were implanted in 700 patients (aortic valve replacement [AVR], 334; mitral valve replacement [MVR], 292; tricuspid valve replacement [TVR), 6; and multiple valve replacement, 68). One hundred and thirty-seven patients (19.6%) had had previous cardiac operations. Concomitant aortocoronary bypass was performed in 127 patients (18.1%). There were 52 hospital deaths, for a mortality of 7.4% (AVR, 4.8%; MVR, 9.2%; multiple valve replacement, 11.8%). Total follow-up was 1,047 patient-years (range, 6 to 60 months, mean, 19.4 months). There were 33 late deaths (AVR, 1.7% per patient-year; MVR, 4.0% per patient-year; multiple valve replacement, 8.1% per patient-year). Eight percent of AVR patients and 47% of MVR and multiple valve replacement patients were taking anticoagulants. The valve-related complications (expressed as events per 100 patient-years) were as follows: (1) thromboembolism (AVR, 0.94; MVR,. 1.42; multiple valve replacement, 4.62); (2) infective endocarditis (AVR, 0.94; MVR, 0.24; multiple valve replacement, 2.31); (3) periprosthetic leak (AVR, 0.94; MVR, 0.71; multiple valve replacement, 3.46); and (4) valve dysfunction (MVR, 0.24). The only case of valve dysfunction was a calcified mitral prosthesis in a 13-year-old girl. Actuarial survival, including operative deaths, was as follows: AVR, 90.5% at 36 months; MVR, 84% at 36 months; and multiple valve replacement, 74% at 24 months. Of surviving patient, 93.6% were in New York Heart Association Class I or II at follow-up evaluation.

Adolescent↗
PubMed1982

Primary cardiac tumors: experience with 25 cases.

The case histories of patients with primary cardiac neoplasms are presented. The mean age was 49.6 years and females predominated (17:8). Nineteen of the tumors were benign (76%), 18 myxomas and one mesenchymal hamartoma. There were six malignant neoplasms; two myxosarcomas, two rhabdomyosarcomas, one skeletal angiomatosis, and one malignant melanoma. The clinical presentation was congestive heart failure in 17 patients and peripheral embolization in five (one patient with both). There were four asymptomatic patients. Antemortem diagnosis was made in 20 patients and five were discovered at autopsy. After 1970, almost 95% of the patients were diagnosed preoperatively while only 14% of the patients had preoperative diagnosis before 1970. Cardiac catheterization and echocardiography were the most useful diagnostic procedures performed but a computed tomographic scan of the heart performed in a patient with right ventricular hamartoma was of great value in delineating the lesion. Twenty-one patients underwent a total of 26 operations but complete excision of the lesion was possible in only 16 patients. Three patients underwent extensive resection and reconstruction. Associated procedures consisted of coronary artery bypass grafts in two patients, mitral valve annuloplasty in one, and a right lung biopsy. Although there was no operative mortality following the original procedure, one patient died after a third operation for recurrence and another underwent unsuccessful emergency pericardiectomy. All patients with malignant lesions died from recurrence 6 to 13 months postoperatively while only three patients in the benign group died and these of unrelated causes. Surgical resection is the treatment of choice for all primary cardiac neoplasms since it is curative in the benign tumors and may prolong life for up to a year with malignant tumors.

Adolescent↗
PubMed1982

Mechanism of regression of mammary adenocarcinomas in rats following plasma adsorption over protein A-containing Staphylococcus aureus.

The plasma from 7,12-dimethylbenz(a)anthracene-induced mammary tumor-bearing rats was adsorbed ex vivo with nonviable protein A-containing Staphylococcus aureus Cowan I and then injected into the rats, along with its original blood cells. Tumors in the treated rats showed significant (p less than 0.005) growth inhibition. There were fewer metastatic nodules; cellular cytotoxicity in the presence of plasma was augmented, and there was increased antitumor cytotoxic antibody activity in treated rats. Plasma from sham-treated rats, however, showed blocking activity. It appears that plasma perfusion over S. aureus decreases blocking activity and augments antitumor immunoreactivity of plasma. The exact mechanism by which growth of 7,12-dimethylbenz(a)anthracene-induced mammary tumors was inhibited in these treated Sprague-Dawley rats is not known. However, it is hypothesized that the observed tumor regression is at least partly attributable to the augmentation of antitumor immunoreactivity in the treated animals.

Adenocarcinoma↗
PubMed1981

Stability of activating systems for in vitro mutagenesis assays: enzyme activity and activating ability following long-term storage at - 85 degrees C.

Activating systems for in vitro mutagenesis assays are commonly prepared and stored at low temperature until required. The objective of the studies reported here was to determine the long-term stability of activating systems stored at - 85 degrees C. A broad range of microsomal enzymes in the postmitochondrial supernatant (PMS) and the microsomal fraction of livers from Aroclor 1254 treated rats were studied in conjunction with the ability of these fractions to catalyse the conversion of dimethylnitrosamine (DMN) and benzo(a)pyrene (B(a)P) to products mutagenic to Chinese hamster ovary (CHO) cells and Salmonella typhimurium TM677. Biphenyl-2- and biphenyl-4-hydroxylase showed a rapid decline in activity on storage, epoxide hydratase activity increased with storage and other enzyme activities studied were relatively stable for up to 32 weeks. No consistent trends in the ability of either the microsomes or the PMS to catalyze DMN or B(a)P induced mutation were observed for up to 12 weeks with CHO cells and 24 weeks with bacteria. It is concluded that low temperature storage of activating systems is an acceptable procedure. However, the results also indicate that certain enzyme activities change during storage, suggesting that aberrant results may be obtained when stored activating systems are used in in vitro tests to screen for mutagens.

Animals↗
PubMed1981

Cardiac valve replacement in the elderly: a review of 320 consecutive cases.

Cardiac valve replacement in 320 consecutive elderly patients (age 65 years and older) was examined retrospectively to determine the results of valvular replacement. From January 1966 to August 1979, 336 valve prostheses (146 mechanical and 190 porcine) were implanted in 320 patients (mean age 68.9 years, range 65-85 years). There were 190 aortic valve replacements (AVR), 116 mitral replacements (MVR) and 16 multiple valve replacements (MR). There were 178 patients ages 65-69 years, 114 patients ages 70-74 years, and 28 patients ages 75 years and older. Twenty (6.3%) had had previous cardiac surgery. Aortocoronary bypass was performed in 59 (18.4%). Twenty-eight patients (8.75%) died in the hospital (AVR 4.7%, MVR 11.4%, MR 37.5%). The mean follow-up was 30.2 months (total 735 patient-years). There were 92 late deaths, or 12.5% per patient year (AVR 11.3%, MVR 14.9%, MR 20.0%). Actuarial survival for all patients at 5 years was 49 +/- 7.6% (AVR 56 +/- 9.7%, MVR 47 +/- 12.5%). Survival at 24 months was 72 +/- 6.3% for ages 65-69 years, 66 +/- 9.2% for ages 70-74 years and 81 +/- 16% for patients 75 years and older. Valve-related complications were infective endocarditis (three mechanical and five porcine), periprosthetic leak (five mechanical and one porcine), valve dysfunction (12 mechanical) and thromboembolism (18 mechanical and seven porcine). At follow-up, 93.2% of surviving patients were in New York Heart Association functional class I or II.

Aged↗
PubMed1981

Embolic complications of porcine heterograft cardiac valves.

From January, 1975, until August, 1978, 509 porcine valves were implanted in 465 patients. Patient follow-up was done at 6 to 45 months (mean 20.2 months), for a total observation of 713 patient-years. There were six early embolic events (mitral four, aortic two). Four of these six patients were in atrial fibrillation and none was receiving anticoagulants at the time of the embolism. There were 18 late emboli. Four occurred in patients with aortic prostheses and produced mild, transient symptoms only. Fourteen occurred in patients with mitral or multiple prostheses. These resulted in death in five patients and permanent sequelae in three. The rate of embolic events was 1.32/100 patient-years for aortic prostheses, 3.27/100 patient-years for mitral prostheses, and 4.91/100 patient-years for multiple prostheses. Thirteen of the 14 patients with emboli were in atrial fibrillation and only three were receiving anticoagulants. Anticoagulation is vital in patients with mitral prostheses who remain in atrial fibrillation, but it appears unnecessary in patients with aortic prostheses and those with mitral or multiple prostheses who remain in sinus rhythm.

Adolescent↗
PubMed1980

Role of I-region gene products in macrophage induction of an antibody response. II. Restriction at the level of T cell in recognition of I-J-subregion macrophage determinants.

The effect of specific anti-I-J reagents on macrophage-T cell interactions was studied in an in vitro antibody response to burro erythrocytes. Macrophages were prepared from the spleens of F1 hybrid mice whose parental strains differed at the I-J subregion. Two F1 hybrids were used for these experiments, [B10.A(3R) X B10.A(5R)]F1 and [B10.S(9R) X B10.HTT]F1. F1 macrophages responded equally well with F1 T-B cells or with T-B cells of either parental strain. When F1 macrophages were pretreated with anti-I-J serum (without complement) specific for one parental haplotype, they were only able to cooperate with T helper (TH) cells of the unblocked haplotype and with F1 TH cells. Identical results were obtained with (Jb X Jk)F1 and (Js X Jk)F1 mice. The results indicate that TH cells possess genetically restricted receptors for macrophage I-J-subregion gene products and that the interaction between this receptor and the macrophage I-J-subregion determinants is essential for the initiation of a primary in vitro antibody response to an erythrocyte antigen.

Animals↗