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Biomedical subjects

A Pol

Publications and source records attributed to A Pol.

At least 55 records · Page 3Linked to original sources
PubMed1994

Isolation of a dimethylsulfide-utilizing Hyphomicrobium species and its application in biofiltration of polluted air.

The methylotrophic bacterium Hyphomicrobium VS was enriched and isolated, using activated sewage sludge as inoculum in mineral medium containing dimethylsulfide (DMS) at a low concentration to prevent toxicity. DMS concentrations above 1 mM proved to be growth inhibiting. Hyphomicrobium VS could use DMS, dimethylsulfoxide (DMSO), methanol, formaldehyde, formate, and methylated amines as carbon and energy source. Carbon was assimilated via the serine pathway. DMS-grown cells respired sulfide, thiosulfate, methanethiol, dimethyldisulfide and dimethyltrisulfide. To test Hyphomicrobium VS for application in biofiltration of air polluted with volatile sulfur compounds two laboratory scale trickling biofilters with polyurethane and lava stone as carrier material were started up by inoculation with this bacterium. Both methanol- and DMS-grown cells could be used. Only a short adaptation period was needed. Short term experiments showed that high concentrations of DMS (1-2 mumol l-1) were removed very efficiently by the biofilters at space velocities up to 100 h-1.

Air Pollutants↗
PubMed1992

Signal-averaged electrocardiography and detection of heart transplant rejection: comparison of time and frequency domain analyses.

To evaluate the role of the signal-averaged electrocardiogram (ECG) in the detection of heart transplant rejection, findings on 277 ECGs were compared with those in 218 endomyocardial biopsy specimens in 25 patients followed up for a median duration of 5.2 months (range 7 days to 17.5 months). Signal-averaged ECGs obtained at intervals of 16.4 +/- 22.3 days were analyzed in the time domain before and after high pass filtering at 25 and 70 Hz. Frequency domain analysis was performed with use of a fast Fourier transform algorithm. Sixteen severe rejection episodes requiring treatment were observed. These episodes induced significant decreases in peak and root-mean-square voltages of both filtered and unfiltered QRS complexes, as well as in the total spectral area. Conversely, QRS duration and 50- to 250-Hz or 70- to 110-Hz spectral areas were not significantly altered. In 14 cases mild rejection episodes were observed that did not significantly alter any of the variables studied. The root-mean-square voltage of the 70-Hz high pass filtered QRS complex was found to be the most accurate variable in detecting rejection. Moreover, this variable was also the most reproducible in 10 healthy control subjects. The optimal rejection criterion was defined as an 11% decrease in voltage between two consecutive recordings. It provided 87.5% sensitivity with 78.4% specificity. In conclusion, the signal-averaged ECG is helpful in the management of heart transplant rejection. Frequency domain analysis of the QRS complex does not increase the accuracy of the technique compared with the time domain approach.

Adult↗
PubMed1992

[Primary Aspergillus endocarditis. Apropos of a case and review of the international literature].

The authors report a case of primary aspergillus endocarditis with endophthalmitis and vertebral osteomyelitis. No underlying disease and no predisposing factors were found. Valve replacement plus combined antifungal chemotherapy proved to be effective as the patient is asymptomatic 18 months after the first symptoms. 48 cases of aspergillus endocarditis, without prior cardiac surgery have been reported in the literature. Aspergillus endocarditis was valvular or mural. Extracardiac dissemination was common but endophthalmitis and osteomyelitis were infrequent. In 11 cases, the diagnosis was made by histologic examination of embolectomy or ocular, skin biopsy tissue. All patients were febrile. Blood cultures showed no Aspergillus species. Clinical manifestations of endocarditis were described in less than fifty per cent of cases. Echocardiographic visualization of vegetations was obtained in 5 cases. Many patients experienced embolic phenomena. Mortality from Aspergillus endocarditis is extremely high (96%). Surgery is the main treatment, consisting of valve replacement. Antifungal chemotherapy should be combined. The proper duration and dosage and the combination of antifungal drugs have not been clearly defined.

Amphotericin B↗
PubMed1991

Analysis of risk factors for surgical wound infections following vascular surgery.

Although surgical wound infections (SWI) following implantation of prosthetic devices can be catastrophic and often require removal of the prosthesis, few studies have identified risk factors for these infections. We conducted a prospective multicenter study to identify risk factors for SWI. Of 561 vascular surgery patients enrolled in the study, 23 (4.1%) developed SWI. Multivariate analysis using logistic regression analyses identified surgery on lower extremities, delayed surgery, diabetes mellitus, past history of vascular surgery, and short antimicrobial prophylaxis (three doses of cefamandole) as independent risk factors for SWI. Consequences of SWI were serious; two (9%) died, 11 (48%) required reoperation, and five (22%) had their prosthesis removed. A risk index was developed using the independent risk factors for SWI identified by logistic regression analyses. When no risk factors were present, no SWI was observed (0 of 100), and the rate of SWI increased from 2.5% when one risk factor was present to 53.8% (7 of 13) when greater than or equal to 4 risk factors were present.

Cefamandole↗
PubMed1991

Cold blood cardioplegia and warm cardioplegic reperfusion in heart transplantation.

The major cause of early death after heart transplantation is graft failure. In 99 consecutive heart transplantations two protocols of myocardial protection were employed. In group 1 (n = 38) initial cold crystalloid cardioplegia combined with cold saline storage and peroperative surface cooling was used. In group 2 (n = 61) cold crystalloid cardioplegia was injected initially and cold blood cardioplegia (Buckberg) was infused every 30 min as soon as the graft arrived in the operating room. No surface cooling was used. Warm blood cardioplegic reperfusion was administered before removal of the aortic clamp. There were 8 early (within 30 days) deaths in group 1 and 6 in group 2 patients. In group 1 there were 5 cardiac deaths against 3 in group 2. Mean ischemic time was 153 +/- 37 min in group 1 and 158 +/- 51 min (p greater than 0.05) in group 2. The post-transplantation need for catecholamines was ten times higher in group 1 patients than in group 2. The first endomyocardial biopsy (after 1 week) showed cytologic lesions compatible with ischemia in 40% of group 1 and only 9% in group 2 patients. We conclude from this initial experience that intermittent cold blood cardioplegia and warm blood cardioplegic reperfusion are useful in heart transplantation in restoring the damage suffered by the graft during brain death and graft storage.

Adult↗
PubMed1991

Bipolar atrial triggered pacing to restore normal chronotropic responsiveness in an orthotopic cardiac transplant patient.

A not uncommon arrhythmia in cardiac orthotopic transplantation patients is sinus node dysfunction with chronotropic incompetence. This is a result of the surgical procedure that denervates the donor heart while the native sinus node may be normal but isolated in the remnant of the recipient atrial wall that serves as the anastomotic site. We were able to restore "normal sinus node function" in a heart transplant patient utilizing a bipolar single chamber pacemaker programmed to the triggered mode. A single unipolar active fixation lead was positioned in each atria. Both leads were connected to a bipolar AAT pulse generator utilizing a Y adaptator. The native atrium with its innervated intact sinus node effectively drove the donor atrium and thus the heart.

Arrhythmia, Sinus↗
PubMed1991

[Prognostic value and development of late potentials after aortocoronary bypass. A prospective study of 100 patients].

Ventricular late potentials are post-infarction markers of the risk of ventricular tachycardia and sudden death. In order to assess their prognostic value and evolution after coronary bypass surgery, 100 patients underwent signal-averaged electrocardiographic recordings 24 hours before and 9 days after surgery, and were then prospectively followed up for 40 +/- 8 months. Patients who displayed late ventricular potentials underwent an additional recording at 5 months with 24 hour Holter monitoring. The average age of the patients was 57.0 +/- 8.4 years; 55 had previous myocardial infarction; 32 had triple vessel disease; the mean left ventricular ejection fraction was 59.7 +/- 12.4%. Ventricular late potentials were recorded in 17 patients before surgery and their left ventricular ejection fraction was significantly lower (51.4 +/- 11.5% vs 61.4 +/- 11.9%: p less than 0.05). There was one operative death in a patient with late ventricular potentials. After surgery, late ventricular potentials were only recorded in 6 patients: at the 9th postoperative day in 3 cases and at the 5th postoperative day in 3 cases. Ventricular late potentials appeared postoperatively in 5 patients, 4 of whom had suffered perioperative myocardial infarction. The recordings became normal at the 5th month in 2 of these 5 patients. Holter monitoring at the 5th month compared with a control group, showed a significant correlation between left ventricular potentials and frequent repetitive or polymorphic ventricular extrasystoles. The 40 month survival rate was excellent: 2 patients were lost to follow-up; there were 3 cardiac deaths, one of which was sudden and 4 non-cardiac deaths. All patients with late ventricular potentials were still alive. These results show that late ventricular potentials persist after coronary bypass surgery in 2/3 of patients; their prognostic significance is not obvious. The low incidence of postoperative sudden death could be attributed to the favourable overall effects of revascularisation rather than on the arrhythmogenic substrate.

Adult↗
PubMed1991

[Circumferential laser thermo-exclusion of post-infarction ventricular tachycardia. Apropos of 11 cases].

Circumferential laser thermoexclusion was assessed in the treatment of postinfarction ventricular tachycardia resistant to drug therapy in 11 patients between December 1986 and April 1989. There were 10 men and 1 woman with an average age of 63.7 +/- 5.6 years whose ventricular tachycardia occurred 10.7 +/- 7.5 years after infarction. All had left ventricular aneurysm or an akinetic plaque. Circumferential thermoexclusion was carried out by Mesnildrey's method, systematically associated with resection of the aneurysm or, when this was not feasible, with coronary revascularisation. Programmed ventricular stimulation was performed before and after surgery in 8 patients. Sustained ventricular tachycardia remained inducible in 4 patients after surgery but the prescription of antiarrhythmic drugs in 2 of these cases resulted in tachycardia becoming non-inducible. The increase in the left ventricular ejection fraction after surgery was not statistically significant (36.9 +/- 9.4% to 44.4 +/- 12.8%). After an average follow-up of 16.7 +/- 10.6 months, there were 2 cardiac deaths not related to arrhythmias (18%), 1 early at the 20th postoperative day and 1 late, 10 months after surgery. There were 2 recurrences of tachycardia (18%) controlled by antiarrhythmic therapy. Late ventricular potentials were recorded in 9 out of the 11 patients before surgery but in only 3 of these cases (33%) after surgery. Circumferential laser thermoexclusion guided visually in the border zone of the infarct scar would seem to be a simple, safe, rapid and therefore attractive, surgical antiarrhythmic technique, the efficacy of which should be evaluated by programmed ventricular stimulation. This should be undertaken on a large scale in order to define the indications and results of this method.

Aged↗
PubMed1989

[Durability of the Carpentier-Edwards porcine bioprosthesis in aortic or mitral positions. 10 years' results on 458 surgically treated cases].

458 patients with a Carpentier-Edwards porcine bioprosthesis (aortic (Ao): 169, mitral (Mi): 289) operated between January 1975 and December 1981, were studied during the first trimester of 1987. Forty seven patients underwent an associated operation. The total follow-up was 3,001 patient-years with a maximum follow-up of 11.4 years and a mean follow-up of 6.5 years. Only 5.6% of patients were lost to follow-up. The patients were aged between 20 and 80 years. The actuarial 9-year survival rate was 69.2 +/- 6.3% for aortic prostheses and 79.6 +/- 3.9% for mitral prostheses. The principal cause of valve failure, appearing with a considerable frequency after 5 years, was primary tissue degeneration which alone represented 67.8% of the causes of valve failure. The rate of absence of valve failure, for all causes combined, was 77.8 +/- 5.9% for the aortic position and 74.9 +/- 4.9% for the mitral position. The actuarial rate of absence of primary tissue degeneration at 9 years was 79.7 +/- 4.1% for aortic prostheses and 75.2 +/- 4.4% for mitral prostheses. The frequency of tissue degeneration decreased with increasing age, representing 2.9%, 1.9% and 1.5% patient-years respectively for the age-groups: 20 to 39 years, 40 to 59 years and 60 to 80 years. However, this difference was not statistically significant. Tissue degeneration was the principal cause for reoperation (n = 59) with an operative mortality of 7.8%.

Actuarial Analysis↗
PubMed1988

Fermentation of methanol in the sheep rumen.

Sheep fed a hay-concentrate diet were adapted to pectin administration and ruminal infusion of methanol. Both treatments resulted in a strong increase in the rate of methanogenesis from methanol. Quantitative data show that methanol was exclusively converted into methane. Treatments did not influence ruminal volatile fatty acid percentages.

Animals↗
PubMed1985

[Hematologic changes induced by extracorporeal circulation].

The plasma and cellular changes seen during the use of extracorporeal circulatory circuits define the system's degree of haemocompatibility. Heparin is still very much used to prevent activation of the blood clotting mechanisms and to reduce their effects. The fall in concentration of the clotting factors and their inhibitors is usually moderate; it is due to haemodilution, particularly important in cardiac surgery and during plasma exchanges. Fibrinolysis is often activated. In cardiac surgery, it is seen in nearly 20% of cases straight after the end of the ECC, and in nearly 80% of cases during the ECC. In all cases of resin haemoperfusion, there is an early transitory fibrinolytic burst, seen only rarely during haemodialysis and plasma exchanges. This phenomenon is usually well controlled by the natural inhibitors; it can be prevented by antifibrinolytic drugs. Cellular changes show the same trends during cardiac surgery, haemoperfusion and haemodialysis. Thrombopaenia is seen within a few minutes starting of ECC. It is caused by platelet activation, with aggregate formation; these are then trapped by the microcirculation. Leukopaenia occurs at the same time, later followed by rebound; complement activation could be the main cause by forming aggregates of polymorphonuclear cells and monocytes. Intravascular mechanical haemolysis reaches significant levels only in a few cardiac surgical procedures. The great speed of activation of the plasma and platelet enzyme systems by the ECC circuits explains these early changes. They are not only due to direct effects of the physiological circulatory characteristics and to contact with artificial surfaces, but also to plasma-cell interactions and to the patients' reaction to these first alterations.

Blood Cell Count↗