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Biomedical subjects

U Althaus

Publications and source records attributed to U Althaus.

At least 73 records · Page 4Linked to original sources
PubMed1993

Absence of rhodamine 123-photochemotoxicity in human tumor xenografts.

Rhodamine 123 (R123)-photochemotoxicity was assessed in BALB/c nude mice bearing a xenografted human squamous cell carcinoma at various power densities and wavelengths and a given incident fluence of 150 Joules/cm2. One hour before light delivery, 1 mg R123/kg was injected i.p. in 20 animals. Surface irradiance was performed on the tumor and an equal size hind leg area of 40 animals. Three groups of 10 animals were treated at 514.5 nm and 0.1 W/cm2, 1 W/cm2, and 30 W/cm2, and one at 488 nm and 30 W/cm2. In each group, five animals received R123. The R123 concentration was measured in the tumor (0.023 +/- 0.007 micrograms/g) and tumor-free tissue (0.023 +/- 0.008 micrograms/g) in three additional animals by high performance liquid chromatography 1 hour after R123-administration. Histologic assessment 72 hours after light delivery revealed no tissue damage at nonthermal power densities, either in the tumor or in the tumor-free tissue, irrespective of R123-administration. At 30 W/cm2, neither in the tumor nor in tumor-free tissues was there any significant difference in the depth of necrosis, irrespective of R123-administration and the wavelength applied. Our results question the validity of R123 as a photosensitizer, at least in this rodent tumor model.

Animals↗
PubMed1993

Experimental assessment of thrombogenicity in vascular prostheses before and during prostaglandin E1 treatment.

The effect of prostaglandin E1 (PGE1; Prostavasin), a powerful platelet blocking agent, was assessed on various new synthetic or biological prostheses in a 6-min in vivo extra corporal arterio-venous (AV) shunt. In eight anaesthetised and heparinised minipigs (weight 25.1 +/- 1.9 kg) the following materials were tested before and during PGE1 infusion (alprostadil-alpha-CD; 40 micrograms/50 ml NaCl/50 min or 0.8 microgram/min): PTFE, (Gore-tex, TW, 4 mm ID); Xenograft, Biologic (Solcograft, 5 mm ID), (non-porous) and Dacron (Atrium, 4 mm ID); polyurethane 1 (Braun-Melsungen, 4 mm ID); polyurethane 2 (S. Gogolewski, 4 mm ID), (porous). Technetium-labelled platelet deposition and blood flow were measured; morphology was assessed by scanning electron microscopy (SEM) and histology. Compared to control levels, PGE1 infusion had a significant systemic effect on mean arterial pressure required by the protocol (MAP 82.6 vs. 66.6 mm Hg; p < 0.001) and flow (173.6 vs. 134.8 mm/min; p < 0.001). Standardised platelet counts per area showed a marked overall decrease from 197 to 130 counts/min/mm2; NS). The morphological assessment by SEM showed a slight increase of surface cellular deposition (score: 6.7 vs. 8.3), the histology score being unchanged (3.9 vs. 3.7). Looking at deposition of platelets for each prosthesis, the porous materials showed a net improvement after PGE1 treatment as compared to non-porous materials. We conclude that PGE1 may be of benefit by reducing platelet deposition in synthetic porous vascular prostheses in the early phase.

Alprostadil↗
PubMed1993

Traumatic rupture of the thoracic aorta in childhood with special reference to the therapeutic strategy.

Acute traumatic tear of the thoracic aorta is extremely rare in childhood. Based upon our own experience with two children, the essential diagnostic and therapeutic measures are discussed with special reference to timing of surgery. Aortic disruption must be suspected in a child who sustains severe blunt chest injury and develops an abnormally wide mediastinum. Definite diagnosis is established by aortography or computed tomography. The appropriate therapeutic approach is determined by the clinical symptomatology and particularly by the severity of concomitant lesions. In the absence of a significant hemothorax and if no difference in pulse amplitude between upper and lower extremities is evident, the risk of free aortic rupture with intrathoracic exsanguination is presumed to be rather low if the patient reaches the hospital alive. In that situation, the continuity of the injured aorta is maintained by the adventitia and surrounding mediastinal structures. Therefore, these patients may derive the best benefit from an initially conservative management including pharmacological intervention to reduce the risk of free aortic rupture. This concept is particularly indicated if aortic disruption is associated with severe concomitant injury such as intraabdominal or intracranial lesions. Such injuries preclude safe aortic repair immediately after establishment of diagnosis. Delay of aortic repair until recovery from associated major injury allows heparinization and the use of a pump oxygenator, which is regarded as the most effective method to prevent spinal cord ischemia and to reduce the risk of paraplegia.

Adolescent↗
PubMed1993

Reduction of plasma cold agglutinin titers by means of plasmapheresis to prepare a patient for coronary bypass surgery.

A 53-year-old man with abnormally elevated cold agglutinins was treated successfully by plasma exchange so that he was able to sustain coronary artery surgery and extracorporeal circulation. Two plasma exchanges, consisting in the exchange of one plasma volume with a 5% albumin solution each, were performed in our intensive care unit with careful monitoring of vital parameters. The plasma exchanges resulted in a reduction of the titer of the cold agglutinins and of the thermal amplitude as well. With the exception of postoperative bleeding requiring re-intervention, the patient was successfully operated and could be dismissed on the 16th postoperative day in good condition.

Agglutinins↗
PubMed1993

[Therapy of pulmonary arteriovenous aneurysm].

Connections of branches of the pulmonary artery to branches of the pulmonary vein resulting in aneurysmatic dilatation are defined as pulmonary arterio-venous aneurysm (pava). The spontaneous course shows a morbidity of 26% and a mortality of 11% within a six-year observation period following diagnosis. If there is an arterial branch with small diameter (< 15 mm) we recommend the embolisation with the catheter; this procedure is less stressing for the patient and does not involve the loss of pulmonary tissue. If the arterial branch has a big diameter, if a complex pava or a pulmonary abscess is present a conventional surgical resection should be envisaged.

Adult↗
PubMed1993

[Intraoperative aspiration and reinfusion of autologous blood in resection of abdominal aortic aneurysms with Solcotrans plus].

Quantitative and qualitative assessment of intraoperative aspiration and reinfusion of autologous blood with the Solcotrans was carried out in 11 males (52-79 years) undergoing elective resection of abdominal aortic aneurysms. Hematology, blood chemistry, coagulation parameters and complement activation were studied in the patient's blood at the following time points: preoperatively, before and after heparinisation, after retransfusion of the first and last Solcotrans, 6 and 20 hours postoperatively. In addition the same quality control was performed in the first and last Solcotrans blood. Results (mean values of 11 patients +/- 1 SD): Intraoperatively 2-3 Solcotrans units were salvaged (total 1039 +/- 565 ml) of which 805 +/- 487 ml were retransfused to the patients. As a mean patients required only 1 unit of homologous RBC's (395 +/- 781 ml) intraoperatively. Patient's intraoperative hemoglobin concentration amounted to 10 g/dl or more. Whereas the hemoglobin level in the Solcotrans attained only 8.2 g/dl. Thrombocyte counts (48 +/- 18 x 10(9)/l) and ionized calcium (0.2 +/- 0.4 mmol/l) were significantly depressed when compared to the preoperative patient values (p < 0.05). The protein concentration remained within normal limits in the patient's and in the Solcotrans blood. Complement activation (C4a, C5a [des Arg]) showed a significant increase after initiation of surgery and there was no significant difference between the solco- or patient blood. Whereas plasma free hemoglobin, coagulation and fibrinolysis parameters showed a significant elevation in the Solcotrans blood. In conclusion the solcotrans system offers a fast, efficient and simple method for salvage and retransfusion of intraoperative autologous blood.

Aged↗
PubMed1993

Thoracoscopic pleurectomy for treatment of complicated spontaneous pneumothorax.

This report describes a thoracoscopic approach for performing parietal pleurectomy. We have developed and used this technique successfully in 12 patients for treatment of recurrent spontaneous pneumothorax with extended bullous lung alterations (stage 4 according to the classification of Vanderschueren). For this purpose we need videoendoscopy and specially designed equipment, including pliable silicone trocars and angled instruments. The mean age of the patients was 38 years; no deaths and no complications occurred. The average period of postoperative hospitalization was 3.3 days. During the follow-up period ranging between 5 and 10 months (mean 7.5), no relapsing pneumothorax was observed.

Adult↗
PubMed1993

[Thoracoscopic lobectomy in the animal model].

To evaluate the possibility of a pure thoracoscopic lobectomy by preparation and selective division of hilar structures we performed left cranial lobectomies in 5 Göttingen mini-pigs. The vessels and the main bronchus were isolated and divided by an Endo-GIA stapler. As an alternative technique we used clips or endoscopic ligation. Inside the thoracic cavity the resected lobes were divided into 2 or 3 parts by the Endo-GIA. They could be extracted without destroying the tissue therefore making macroscopic examination possible. The intraoperative blood loss was minimal and all the pigs survived the operation. Two pigs were sacrificed initially, the remaining three one month later. These three showed no evidence of pleural fistula or atelectasis in remaining lung tissue either macroscopically or histologically. It appears that thoracoscopic selective lobectomy is technically possible at least in pig studies. Further studies will show whether thoracoscopic lobectomy in patient with malignancy is as effective as open radical thoracotomy techniques and if endoscopic mediastinal division is possible.

Animals↗
PubMed1992

[Heart valve substitution: the effect of preoperative findings on long-term outcome].

BACKGROUND: In a retrospective analysis of 653 consecutive patients who underwent heart valve replacement by one single type of mechanical prosthesis (St. Jude Medical) at three Swiss university medical centers (Basel, Bern, Lausanne), the outcome was judged on the basis of preoperative variables. These variables should facilitate the timing of heart valve replacement. METHODS: Preoperative evaluation includes NYHA classification of symptoms, chest X-ray, ECG, and LVEF on angiography. Postoperative outcome was assessed clinically at yearly intervals by NYHA classification, documentation of complications and mortality. RESULTS: Five-year-survival rates were 96 and 88%, and complication-free rates were 82 and 76% respectively in patients after isolated aortic and mitral valve replacement. An unsatisfactory outcome with death or persistent severe symptoms was more frequent when preoperative symptoms at rest and atrial fibrillation were present. CONCLUSION: Heart valve replacement should not be postponed until severe symptoms and functional impairment occur. Clinical criteria are at least as important for the timing of operation as the findings of more complex investigations.

Adolescent↗
PubMed1992

Prevention of cardiac allograft rejection by FK506 and rapamycin: assessment by histology and nuclear magnetic resonance.

We assessed the effect of FK506 and rapamycin (RPM) in a heterotopic abdominal rat heart transplant model using a major histocompatibility mismatch (DA to LEW). The end-point of our study was the histologic grading of rejection (Stanford) and 31P magnetic resonance spectroscopy (MRS) at 1 week after transplantation. Two dosages of FK506 (2.0 and 8.0 mg/kg per os daily) and RPM (1.5 and 6.0 mg/kg intraperitoneally daily) were compared in allografts without and with cyclosporine (12.5 mg/kg per os daily) treatment. The results show: Weak heartbeat and full rejection at day 5 in all untreated allografts; severe rejection in groups on a low dose of FK506 and RPM; mild rejection in both high dose groups comparable to the results of the hearts treated with cyclosporine; MRS does not allow differentiation between no or mild forms of rejection. Energy-rich phosphates are near normal in the high dosage immunosuppression groups but show a significant reduction in the low dosage groups. We conclude that all three tested drugs can reduce the degree of rejection from severe (untreated allografts) to mild if given in an adequate dosage. MRS correlates well with the degree of histologic rejection but permits only the diagnosis of moderate or severe rejection.

Animals↗
PubMed1992

Assessment of new immunosuppressive drugs in a rat cardiac allograft heterotopic model.

We assessed FK506 (FK) and rapamycin (RPM) in a heterotopic abdominal rat heart transplant model using a major histocompatibility mismatch (DA to LEW). The end point of our study was histologic grading of rejection (Billingham and working formulation) at 1 week. Two doses of FK (2.0 and 8.0 mg/kg p.o., q.d.) and RPM (1.5 and 6.0 mg/kg i.p., q.d.) were compared to allografts without and with ciclosporin (12.5 mg/kg p.o., q.d.) treatment. Results show: (1) weak heartbeat and full rejection on day 5 in all untreated allografts; (2) weak heartbeat and high degree of rejection in groups receiving low doses of FK and RPM; (3) strong heartbeat and mild rejection in both high FK and RPM dose groups comparable to the results of the hearts treated with ciclosporin; (4) 1 animal in each high FK and RPM dose group showed possible signs of toxicity, and (5) the strength of the heartbeat was not a reliable indicator of the efficacy of an immunosuppressive drug. We conclude that even in a major histocompatibility mismatch model at the time of the strongest immune response (1 week), all three tested drugs can reduce the degree of rejection from severe (untreated allografts) to mild if given in an adequate dosage.

Animals↗
PubMed1992

Influence of failed arterial reconstruction on the outcome of major limb amputation.

BACKGROUND: Unsuccessful vascular repair may further preexisting limb ischemia and thus increase the risk of revascularization procedures. METHODS: The results of 94 primary major amputations (group A) have been analyzed and compared with 112 secondary ablations (group B) carried out after failed revascularization efforts. All patients suffered from chronic critical ischemia (grades III and IV) of the lower extremities. In group A the severity of ischemic symptoms was more pronounced (trophic changes in 80% vs 66% in group B), and a preponderance for older age, diabetes mellitus, and incidence of cardiac failure and cerebrovascular insufficiency was evident. RESULTS: In patients undergoing secondary amputation the final transection level was adversely affected by preceding unsuccessful reconstructive attempts. In spite of the better risk profile, 30% of patients in group B were subjected to above-knee amputation compared with 13% of patients in group A. The aggravated limb ischemia caused by graft failure is reflected by the decrease of the mean ankle systolic pressure index from 0.27 to 0.13 (before and after failed revascularization attempts). Although more amputations at the below-knee level were performed initially in group A, primary wound healing was obtained among these subjects in 68% of patients (compared with only 39% for patients in group B). CONCLUSIONS: In a substantial number of cases preexisting limb ischemia may be promoted by failed attempts at vascular reconstruction, thus leading to severe wound healing complications and a higher level of amputation.

Aged↗
PubMed1991

[Benefits and side effects of preoperative autologous blood donation in 11 heart surgery patients].

Patients scheduled for cardiac surgery are prone to adverse reactions during blood donation due to hemodynamic instability. 11 selected patients donated three units of red blood cell concentrates and three units of fresh frozen plasma (FFP) preoperatively in 11-day intervals under careful hemodynamic monitoring. 24 hours preoperatively autologous plasmapheresis (500 ml) was carried out in 10 patients at bedside. No complications were seen in any patients. The patients' mean hemoglobin concentrations were 142 +/- 11, 133 +/- 6, 128 +/- 7 and 126 +/- 7 g/l (mean +/- 1 SD) before each autologous blood donation and before the plasmapheresis respectively. No significant changes were noted in major hematological and chemical screening tests. Serum iron, iron-binding capacity and ferritin levels remained within the normal range. Due to additional perioperative blood saving methods, such as reinfusion of centrifuged oxygenator-blood (559 +/- 119 ml) and shed mediastinal blood (518 +/- 353 ml), only two patients needed additional transfusion of 1 homologous red cell unit each. On average 2.18 autologous red cell concentrates were retransfused per patient.

Blood Chemical Analysis↗
PubMed1991

[Accidental hypothermia in Switzerland (1980-1987)--case reports and prognostic factors].

This retrospective study comprises 234 cases of accidental hypothermia (core temperature less than 35 degrees C) hospitalized in 95 Swiss clinics between 1980 and 1987. The most frequent accidents were alpine (n = 78) in origin, followed by cold exposure after injuries (n = 63) and suicide attempts (n = 43). Hypothermia was induced by cold air in 129 cases and by water in 47 cases. Patients were divided evenly between the degree of hypothermia: 75 mild (32-35 degrees C), 79 moderate (28-32 degrees C) and 66 severe (less than 28 degrees C). Among the survivors the coldest patient had a core temperature of 17.5 degrees C and the longest cardiac arrest with a favourable outcome lasted 4.75 hours. Out of the 234 patients 68 died (29%). We assessed all variables relative to outcome, in particular the mechanism of the accident, the mode of cooling, temperature, circulation, age and sex, underlying diseases, rewarming methods, medication and complications during the hospital course. All variables were tested in two multiple regression analysis models (retrospective model n = 181: prospective model n = 128) with regard to significance (p less than 0.05) and survival. Results are expressed with ODD's ratios (OR). The negative survival factors are asphyxia (OR 30), invasive rewarming methods (OR 20), slow rate of cooling (OR 10), asystole on arrival (OR 9), pulmonary edema or ARDS during hospitalization (OR 8), elevated serum potassium (OR 2/mmol/l) and age (OR 1.03/year). The positive survival factors are rapid cooling rate (OR 10), presence of ventricular fibrillation in cardiac arrest patients (OR 9) and presence of narcotics and/or alcohol during hypothermia (OR 5).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Differentiation of cardiac ischemia and rejection by nuclear magnetic spectroscopy.

Nuclear magnetic resonance (NMR) criteria of early cardiac rejection are similar to those seen in myocardial ischemia, that is, a reduction of high energy phosphatases (Pc; ATP) and an increase of inorganic phosphates (Pi). Our aim was to assess in vivo changes of phosphorous spectroscopy (31P) induced by cardiac rejection and myocardial ischemia in the same animal. Heterotopic heart isografts (n = 5) and untreated allografts (n = 5) were examined at seven days on a two tesla wide-bore magnet with a surface coil. Subtotal global ischemia was produced for sequential NMR measurements, followed by heart excision for histological rejection grading (Billingham). Results 1. Isograft served as controls and showed normal energy-rich phosphate compounds and pH. 2. Rejecting (moderate to severe) allografts showed a decrease of Pc/Pi and beta-ATP/Pi ratio compared with isografts. However no significant pH drop could be detected. 3. Induced ischemia was confirmed by marked ECG-ST elevation and showed a significant early global myocardial acidosis (pH less than 6.9) particularly in severe prolonged ischemia (p less than 0.05). 4. Using 31P NMR techniques, ischemically induced changes were similar in isografts and allografts with a trend towards a more pronounced extent in the latter groups. In conclusion, magnetic resonance spectroscopy (31P and pH) allows in vivo differentiation between cardiac rejection and acute myocardial ischemia.

Acute Disease↗
PubMed1991

Major coagulation disorders when using aprotinin--observations on a case.

Intraoperative application of the proteinase inhibitor aprotinin allows to drastically reduce blood loss during and after cardiopulmonary bypass operation. The side effects of this therapy (if any) have not been systematically registered and a possible interaction with heparin is not excluded. Such an interaction seems to have occurred in one of our patients. He developed a resistance to heparin shortly after prophylactic administration of aprotinin and maintained it for about one hour after discontinuation of the aprotinin. Prophylactic and therapeutic implications of this observation are briefly exposed.

Aged↗
PubMed1991

Surgery and chemotherapy for pulmonary metastases: long-term results from a combined modality approach.

Eighty-three patients underwent pulmonary metastatectomy as part of a combined modality approach between 1. 1. 1972 and 31. 12. 1988 and 80 were followed up until 1. 1. 1990 or until death, with an average follow-up of 110 months. The estimated 5-, 10-, and 15-year survival rate was 38%, 32%, and 22% respectively. Recurrent pulmonary metastases were observed in 60% of the patients during follow-up with an estimated 24 months relapse-free survival rate of 50%. An additional 20% of the patients developed extrapulmonary recurrent tumor manifestation without evidence of pulmonary disease. One of five patients remained tumor free up to 207 months (an average of 87 months) after the initial pulmonary metastatectomy. A multivariate analysis identified completeness of tumor removal, the type of primary tumor, and a difference in histology between primary and metastatic neoplasm as three independent prognostic factors with significant impact on overall survival, the completeness of tumor removal being the most important one. Disease-free long-term survival for patients with pulmonary metastases treated by surgery and chemotherapy is related to completeness of tumor removal and the type of primary tumor.

Combined Modality Therapy↗