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Biomedical subjects

D Graf

Publications and source records attributed to D Graf.

69 records · Page 4Linked to original sources
PubMed1988

Morbidity following the Ross operation.

Aortic valve replacement (AVR) with a pulmonary valve autograft (PVA) was first reported by Donald N. Ross in 1967. The expectation of this procedure was to avoid degenerative changes seen in other biological tissue valves such as calcification, attenuation, and rupture of the leaflets. Recent reports by the original investigator's group have confirmed the lack of degenerative changes in PVA. To corroborate their conclusions, the fate of 12 patients undergoing AVR with PVA by Dr. Gonzalez-Lavin has been ascertained. From March 1969 to June 1971, 12 patients underwent AVR with PVA. The right ventricular outflow tract (RVOT) was reconstructed with an aortic homograft valved conduit. The mean age was 42.7 years (range 21 to 52 years). The mean follow-up for 11 hospital survivors is 12.4 years. Three PVAs have been replaced; one following infective endocarditis at 13 years, and two at 15 and 73 months due to technical malalignment. There was no evidence of PVA degeneration during histologic examination of these explanted PVA. Six patients are alive and retain the original PVA at 12 years (55%). This analysis corroborates the conclusions of Dr. Ross and strongly suggests an immunological mechanism in the process of calcification of other biological tissue valves. The Ross operation is believed to be the preferred method of AVR in young patients.

Adult↗
PubMed1988

Homograft valve preparation and predicting viability at implantation.

An experimental study was performed using C14 proline uptake in order to: (1) assess the effects of current sterilization and storage methods on fibroblast viability, and (2) establish a control tissue that could be used to determine viability of each homograft valve at the time of implantation in the clinical setting. The results were expressed as disintegrations per minute per milligram of tissue (DPM/mg). Swine aortic (AV), pulmonary (PV), and tricuspid leaflets (TV), and adjacent AV and PV arterial wall were procured sterile and subjected to routine sterilization and storage. Thirty samples of AV were analyzed for incorporation of labeled proline at procurement (208 +/- 7 DPM/mg), following 48-hour antibiotic exposure (87 +/- 6 DPM/mg, P less than .0001), and following controlled rate cryopreservation and storage for 12 days at -80 degrees C (78 +/- 8 DPM/mg, P = .42). Proline uptake of the other tissues at the same intervals disclosed that only the TV resulted in the same degree of viability at implantation (AV 78 +/- 8, PV 68 +/- 3, TV 75 +/- 2, P = NS). The homograft valves were obtained under sterile conditions from brain dead, multiorgan donors (homovital). It has been postulated that these valves are sterile and ready for implantation. Of 17 homovital valves cultured at procurement, 9 had positive cultures within 48 hours (53%). We conclude that: (1) the TV can be processed as a control tissue with each homograft and then utilized to predict viability at the time of implantation in the clinical setting; (2) antibiotic exposure is an essential step in the preparation of all homografts, however, modification of the antibiotic solution is necessary.

Carbon Radioisotopes↗
PubMed1988

Instantaneous risk of events following aortic valve replacement with pericardial valves: a ten-year experience.

Actuarial curves and linearized rates of occurrence are statistical functions that traditionally have been used to evaluate freedom from, or incidence of, valve-related events that occur as a result of aortic valve replacement (AVR); however, the instantaneous risk of an event can be more precisely pinpointed by the use of a time-related hazard function. This function was used to analyze 240 cases involving patients who underwent AVR with the Ionescu-Shiley bovine pericardial valve. Follow-up was for 10 years. The period from 60 to 70 months after implantation was apparently critical, since specific and cumulative events (intrinsic tissue failure, thromboembolism, prosthetic valve endocarditis, cumulated events, and death due to valve-related events) peaked during this period. We suspect important degenerative bioprosthetic changes take place during this period and are the cause, in part, for this pattern. In an effort to reduce the incidence of thromboembolism, close observation, and probably antiplatelet drug administration, should be initiated 60 months after implantation of this valve.

Journal Article↗
PubMed1988

[Perforation of the large intestine by a contrast medium enema with barium].

This is a report about five patients who suffered a perforation of the colon during a barium-sulfate enema. In one case, barium leaked into the intraperitoneal cavity causing a barium peritonitis. In the other four cases, leakage into the retroperitoneal cavity occurred. All patients underwent surgical removal and drainage of the barium-sulfate and subsequently required a colostomy. In two cases a bowel resection was additionally performed. In one case the defect re-sutured. Antibiotic therapy was included in all cases. All patients survived the incident and were discharged between 20 days and four months postoperatively. Publications and personal experience led us to manage intraperitoneal or large retroperitoneal perforations by prompt laparotomy with removal of barium and faeces. A proximal colostomy is also required. In smaller retroperitoneal perforations conservative management is feasible, however, if the patient's condition deteriorates, they should be treated as recommended for an intraperitoneal perforation.

Aged↗
PubMed1987

Determining viability of fresh or cryopreserved homograft valves at implantation.

Studies of homograft valves in the past two decades have suggested that "viable" valves, i.e., those maintaining chemical and structural integrity of their leaflet intercellular matrix, have a better long-term function than nonviable valves. The most effective qualitative methods of assessing leaflet viability involve destruction of the valve leaflets; thus, these methods have been limited to random use in selected valves. A study was conducted in swine in an attempt to establish a control tissue which could be tested in place of the homograft leaflets, thereby determining viability levels of every valve clinically implanted and correlating the results with long-term clinical function. Thirty samples each of the aortic and pulmonary artery wall and tricuspid leaflet were compared with aortic and pulmonary leaflets. Utilizing the technique of C14-proline uptake, viability was assessed at procurement, following sterilization, and following cryopreservation and short-term storage. The tricuspid leaflet was found to retain the same level of viability as the aortic and pulmonary leaflets before and after the cryopreservation period. It was concluded that the tricuspid leaflet could be utilized as the control tissue.

Animals↗
PubMed1986

[Antibiotic treatment of perforated appendicitis in childhood--a prospective study].

A prospective randomised study (I) was carried out on 130 children undergoing laparotomy for perforated appendicitis. The present study evaluates the therapeutic effectiveness of different antibiotic regimens in modifying the rate of post-operative complications (intraabdominal abscess, ileus, wound infiltration or abscess). During the first year of this study two treatment groups were used. Group A consisted of 29 children treated with Sulfometrol/Trimethoprim; the rate of postoperative complications was 44.8%. Group B consisted of 36 children treated with mezlocillin, the rate of complications being 13.8%. However, the same treatment with mezlocillin during the second year of the prospective study showed an increase of this rte to 39% (28 children--group C). The final group of 37 children was treated during the second year with mezlocillin and metronidazole (group D). The postoperative rate of complications was 10.8%. A retrospective analysis of further 80 children (study II) with perforated appendicitis treated with mezlocillin and metronidazole showed a consistent low rate of postoperative complications at 10.2%. In 6.8% of children studied, an operative intervention was necessary (four cases of ileus, four wound abscesses). The mean postoperative hospitalisation period decreased from 22.7 days in group A to 15.2 days in group D and finally to 14 days in study II. The present study shows that an effective and persistent attenuation of the rate of postoperative complications after perforated appendicitis in children depends on an early onset of therapy and on the appropriate choice of antibiotic drugs that are effective against aerobic and anaerobic microorganisms.

Anti-Bacterial Agents↗
PubMed1985

Dynamic responses to intravenous urapidil and dihydralazine in normal subjects.

Hemodynamic responses after urapidil were compared with those after dihydralazine in placebo-controlled, double-blind studies after cumulative intravenous doses. We recorded heart rate, blood pressure, systolic time intervals corrected for heart rate (electromechanical systole and preejection period), electrical impedance cardiography [(dZ/dt)/RZ index and mean electrical thorax impedance], and M-mode echocardiogram (end-systolic and -diastolic diameters, end-systolic wall stress, fractional shortening, and cardiac output). Both drugs induced dose-dependent reductions in total peripheral resistance, which resulted in reduction in left ventricular end-systolic wall stress and increases in heart rate (limited at +10 bpm with urapidil), fractional shortening, cardiac output, and the (dZ/dt)/RZ index. With each drug, diastolic blood pressure fell by 5 mm Hg, the corrected preejection period shortened (dihydralazine greater than urapidil), the corrected electromechanical systole did not change, and mean electrical thorax impedance rose with urapidil. The spectrum of effects indicates that both drugs reduce left ventricular afterload, thereby increasing left ventricular pump performance. Urapidil also exerts some preload reduction.

Adult↗
PubMed1982

Subcellular metabolism of [3H]-oestrone sulphate in human gestational myometrium.

Human myometrium obtained at caesarean sections from term pregnancies was homogenized and separated into nuclear, mitochondrial, microsomal and cytosol fractions. Purity of the individual fractions was assessed by microscopy and by determination of marker enzymes. Homogenate and subcellular fractions were incubated with [3H]-oestrone sulphate in a concentration of 5 x 10(-10) M after addition of NADPH2 and a coenzyme regenerating system at 37 degrees C. Incubation were terminated after 10, 20, 40, 60, 120 and 180 min. Substrate and metabolites were characterized by repeated chromatographies on Sephadex LH 20 using various solvent systems. Further characterization of the metabolites was achieved by simultaneous chromatography of the isolated compounds and their authentic cold standards. The enzymes involved in the metabolism of oestrone sulphate to oestrone and oestradiol-17 beta are primarily located in the microsomal fraction. After 40 min 71.1%-73.0% was converted to oestrone, while the conversion rate to oestradiol-17 beta was in the order of 1.38-1.90%. Metabolism of oestrone sulphate seen in the other subcellular fractions is probably due to microsomal contamination. The findings presented indicate that human myometrium is capable of converting oestrone sulphate to free oestrone and oestradiol-17 beta under in vitro conditions.

Estradiol↗
PubMed1981

[Megaoesophagus -- differential diagnosis and therapy (author's transl)].

Functional hindrances in passage of the oesophageal tract are particularly recognised in achalasia, which occurs in less than 5% of children. The megaoesophagus accompanying massive gastro-oesophageal reflux can also be a consequence of functional disturbances. In addition, peptic stenosis of the oesophagus usually causes dilatation of this organ. Other organic stenoses are just as rare, whether they are congenital membranous or fibromuscular stenoses, or occur as secondary narrowing of the oesophagus, following accidental acid-burns. Treatment of choice in achalasia is cardiomyotomy with insertion of a fundus patch. Gastro-oesophageal reflux is usually treated conservatively at first. Operation and fundoplication is indicated only when this treatment is unsuccessful, or primarily in peptic stenosis. In congenital membranous stenosis or acid-burn stenosis, forceful treatment with bougies usually attains the desired ends. On the other hand, congenital fibromuscular narrowing generally requires operative resection.

Adolescent↗
PubMedDate not supplied

Events following implantation of an intraluminal ringed prosthesis in the ascending, transverse, and descending thoracic aorta.

From March 1978 through July 1985, 23 patients underwent implantation of 24 intraluminal ringed prostheses (IRP). There were 18 men and 5 women, with a mean age of 54.7 years, range 15-74 years. Eleven IRP were placed in the ascending aorta, two in the transverse arch, and 11 in the descending aorta. Pathology included acute aortic dissection in four patients, chronic dissection in four, and aortic aneurysm in 16. There were eight hospital deaths (35%). Causes of death included acute cardiac failure in seven patients, and ruptured abdominal aortic aneurysm in one. IRP complications requiring revision included right coronary artery occlusion in three of 11 patients (27%) with an IRP in the ascending aorta. Graft revision was also required in three of 11 IRP implanted in the descending aorta (27%), due to graft occlusion in one and graft stenosis in two. Of the six patients with IRP complications, there were three hospital deaths (50%). All 15 hospital survivors were followed for a mean of 68.5 months, range 5-112 months. There were four late deaths (26.7%). Causes of late death included hemoptysis in one, cardiomyopathy in one, and aortic redissection and rupture in two. We conclude that patients undergoing repair of aortic pathology with IRP have an important risk of early phase events, as technical problems can occur due to malposition and slippage of the securing rings.

Adolescent↗
PubMedDate not supplied

[Relation between grades of histologic differentiation and hormone receptors in breast cancer].

The relationship between the grade of histologic differentiation of the tumor and estrogen (ER) and progesterone (PgR) receptor values was analyzed in 261 patients with breast cancer of the invasive duct type. There was a statistically significant difference in concentration and incidence of positive and negative ER and PgR with regard to histologic grade. The concentration and number of positive hormone receptors increased with better differentiation of the tumor. A statistically significant correlation between histologic grade, hormone receptor values and axillary nodal involvement was obtained only in patients with no metastases to axillary lymph nodes.

Breast Neoplasms↗