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Biomedical subjects

F Hess

Publications and source records attributed to F Hess.

At least 19 recordsLinked to original sources
PubMed2004

Transdiaphragmatic pleural lavage in penetrating thoracoabdominal trauma.

BACKGROUND: The purpose of this study was to determine the incidence of thoracic sepsis following a systematic thoracic cavity washout through the injured diaphragm in patients with penetrating thoracoabdominal trauma. METHODS: Prospectively collected data on all patients presenting with penetrating thoracoabdominal trauma between July 1999 and July 2002 were analysed. Patients with peritoneal biliary-gastroenteric (BGE) contamination and a diaphragmatic laceration were managed by laparotomy and transdiaphragmatic thoracic lavage. RESULTS: A total of 217 patients had penetrating thoracoabdominal injuries, of whom 110 had BGE contamination of the peritoneal cavity with spillage into the pleural cavity. The mean Injury Severity Score was 38.1. Gunshot and stab wounds occurred in 79 (71.8 per cent) and 31 (28.2 per cent) respectively. Contamination was from the stomach (55.4 per cent), large bowel (37.3 per cent), small bowel (29.1 per cent), gallbladder and bile ducts (9.1 per cent) and pancreas (6.4 per cent). Thoracic complications occurred in six patients (5.5 per cent): empyema in two, Escherichia coli-related pneumonia in three and pleuritis in one. There were no deaths. CONCLUSION: A thoracic washout through the injured diaphragm in patients with penetrating thoracoabdominal trauma and BGE contamination was associated with a low rate of intrathoracic septic complications.

Abdominal Injuries↗
PubMed2003

Obstacle avoidance during human walking: H-reflex modulation during motor learning.

The goal of this study was to investigate changes of H-reflex amplitudes during a motor learning task. Subjects with reduced vision were instructed to step over an obstacle on a treadmill as low as possible, while the soleus H-reflex was elicited. Acoustic warning and feedback signals about performance were provided. Performance improvement was associated with a decrease of muscle activity, needed to step over the obstacle (rectus femoris, biceps femoris, tibialis anterior and gastrocnemius medialis muscles), and of foot clearance, while joint angle trajectories from knee and ankle became more stable. The experiment consisted of five runs, three with normal treadmill walking and two with randomly stepping over the obstacle (100 times). H-reflexes were elicited at early and late stance phase before stepping over the obstacle. H/M ratio, latency and duration were determined. The values of these measures were calculated for the onset and end of a run and their course over time was evaluated using a correlation coefficient. The largest adaptations with a significant increase of reflex amplitude occurred during the first obstacle run. This increase lasted only briefly and the reflex amplitudes decreased to their previous values. During the later obstacle run, no H-reflex modulation occurred. It is concluded that a motor learning task causes adaptational effects not only on performance, but also on H-reflex responses. The results indicate that most of the modulation of H-reflexes is probably due to supraspinal influences on reflex transmission. The observations made are probably less specific for this motor task (stepping over the obstacle), but rather associated with the increased attention required by the motor learning task during the first obstacle run.

Adult↗
PubMed2000

LDL-receptor-related proteins in Wnt signal transduction.

The Wnt family of secreted signalling molecules are essential in embryo development and tumour formation. The Frizzled (Fz) family of serpentine receptors function as Wnt receptors, but how Fz proteins transduce signalling is not understood. In Drosophila, arrow phenocopies the wingless (DWnt-1) phenotype, and encodes a transmembrane protein that is homologous to two members of the mammalian low-density lipoprotein receptor (LDLR)-related protein (LRP) family, LRP5 and LRP6 (refs 12-15). Here we report that LRP6 functions as a co-receptor for Wnt signal transduction. In Xenopus embryos, LRP6 activated Wnt-Fz signalling, and induced Wnt responsive genes, dorsal axis duplication and neural crest formation. An LRP6 mutant lacking the carboxyl intracellular domain blocked signalling by Wnt or Wnt-Fz, but not by Dishevelled or beta-catenin, and inhibited neural crest development. The extracellular domain of LRP6 bound Wnt-1 and associated with Fz in a Wnt-dependent manner. Our results indicate that LRP6 may be a component of the Wnt receptor complex.

Animals↗
PubMed1998

Sensitive ELISA dipstick test for the detection of chloroquine in urine under field conditions.

OBJECTIVE: To evaluate a new enzyme-linked immunosorbent assay (ELISA) dipstick test for detecting chloroquine (CQ) in urine in a malaria-endemic region of north-western Namibia. METHOD: Urine samples from 92 patients attending the outpatient department of Kamhaku Hospital with suspected malaria infection were tested for CQ with both the Dill-Glazko test and the ELISA dipstick test. Results were compared to the history of CQ intake as documented in the patients' health passes. RESULTS: The dipstick test proved an easy-to-handle and very sensitive tool for the detection of CQ with a lower limit of detection at 120 nmol/l. It showed high agreement with the history of CQ intake within the last 6 months. The specificity in a negative control group was 100%. The Dill-Glazko test was far less sensitive and specific with a lower detection limit of 150 micromol/l. CONCLUSION: The dipstick test can be used in pharmacological studies to evaluate the use of CQ, and as an inclusion criterion for in vivo and in vitro sensitivity tests, whereas the Dill-Glazko test is appropriate to test compliance during and a few days after CQ intake.

Adolescent↗
PubMed1997

Pharmacology of kinins in the arterial and venous mesenteric bed of normal and B2 knockout transgenic mice.

We have tested the vasoactive effects of kinins in addition to various other endothelium-dependent or independent agonists in the arterial and venous perfused mesenteric circuits of the mouse. Bradykinin (0.1 pmol-100 nmol), but not des-Arg9-bradykinin (10 nmol) induced a dose-dependent vasodilation of the precontracted arterial and venous mesenteric vasculature of the mouse. Furthermore, acetylcholine (2.5 nmol) also induced a marked arterial vasodilation but was without effect on the venous side. Other endothelium-dependent vasodilators, such as platelet-activating factor (PAF) (1 nmol), tachykinin NK1 selective agonist ([Sar9,Met(O2)(l1) ]substance P) (0.5 nmol) and adenosine diphosphate (5 nmol), were without effect on either side of the mesenteric bed of the mouse. The bradykinin B2 receptor selective antagonist (HOE 140) abolished the arterial and venous vasodilation induced by bradykinin without affecting that of acetylcholine or sodium nitroprusside. In addition, the bradykinin B1 receptor antagonist des-Arg9-[Leu8]bradykinin was without effect on the responses induced by bradykinin. A nitric oxide synthase inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) markedly reduced, whereas removal of the endothelium with 3-[3-cholamidopropyl)dimethylammonio]-1-propane sulfonate (CHAPS) abolished dilatation to bradykinin and acetylcholine (arterial side only) without affecting that induced by sodium nitroprusside in the mouse arterial and venous mesenteric circuits. In the same two circuits of transgenic B2 knockout mice, the vasodilatory responses to bradykinin were absent, whereas the arterial circuit still responded to acetylcholine by a L-NAME-sensitive vasodilation. Our results suggest the exclusive contribution of B2 receptors located on the endothelium in the vasodilatory effects of bradykinin in the arterial and venous mesenteric circuits of the mouse.

Animals↗
PubMed1996

Salt-sensitive hypertension in bradykinin B2 receptor knockout mice.

The kallikrein-kinin system regulates water and sodium excretion and thus plays a role in blood pressure (BP) homeostasis. We tested the hypothesis that mice lacking the gene encoding for the bradykinin B2 receptor (B2-KO) have a greater hypertensive response to chronic high Na+ intake (salt sensitivity) compared to controls. We also obtained dose-response curves for different vasoactive substances in both groups. The hypertensive effect of high Na+ intake was almost doubled in B2-KO mice compared to controls. A high-Na+ diet increased heart and kidney weight in B2-KO, but not in controls, suggesting an increased afterload in B2-KO mice. The BP response to bradykinin was completely abolished in B2-KO, but that to acetylcholine was conserved. The hypertensive response to angiotensin II was not exaggerated in B2-KO mice. This study describes a new salt-sensitive animal model and suggests that in mice kinins play a role in preventing salt-sensitive hypertension.

Acetylcholine↗
PubMed1996

Geographic differences in the sensitivity of a polymerase chain reaction for the detection of Plasmodium falciparum infection.

The amplification of target DNA by highly specific probes using the polymerase chain reaction (PCR) provides a highly sensitive and specific method for the detection of malaria infection. The use the of PCR in settings with varying endemicity within one survey area has not been investigated intensively. Therefore, a cross-sectional study was conducted in the districts of Kabarole and Bundibugyo in western Uganda using material from three villages with different epidemiologic situations regarding malaria and DNA primers for a PCR that had shown satisfactory sensitivity and specificity in previous trials. The sensitivity of the PCR varied significantly (P < 0.001) in the three survey villages (between 63.2% and 83.9% for the primer pair K1-14-1 and between 37.9% and 69.9% for the primer pair MSP-1) and was highly linked to geographic differences and social exchanges of the inhabitants with other areas of the district. According to the results of this investigation, it is advisable not to use a single primer pair in epidemiologic field studies for the detection of falciparum malaria. The use of combined primer pairs and the frequent confirmation of the results by microscopy are recommended.

Animals↗
PubMed1996

[Total skin electron beam irradiation in cutaneous T-cell lymphoma].

PURPOSE: Patients with cutaneous T-cell lymphoma are treated in Germany mostly by dermatological local therapy like corticosteroids or PUVA-irradiation. Total skin electron beam irradiation is used rarely, even though it has a potentially curative character. We present an analysis of patients, who received a total skin electron beam irradiation after having progressive disease following other treatment modalities. PATIENTS AND METHODS: Twenty-one patients (mean age 58.9 years) in different stages were treated (stage IB and IIA n = 4, stage IIB n = 8, stage III n = 3, stage IV n = 6). All patients had progressive disease under other forms of local therapy. The irradiation was performed from 6 directions per hemibody using 2 axial fields which have each an 18 degree angle to the horizontal level. Six and 7 MeV fast electrons were used. Total dose was between 8 and 36 Gy in single dosis of 1 x 4 up to 5 x 2 Gy per week. In underdosed areas and areas of tumors of the skin boost irradiation with small fields was given. RESULTS: All patients had a good tumor regression (complete remission: n = 10, partial remission: n = 11). With the follow-up between 4 and 93 months total- and recurrence-free survival was 18 and 7 months (median). Patients in early stages with slow but complete remission of the symptoms had the best prognosis. Because of the small case number there was no significant difference between the groups. There were no severe side effects of the radiotherapy noted. CONCLUSION: Our analysis shows on a small patient number, that total skin electron beam irradiation has a good palliative effect on patients who have progressive disease following other types of treatment like PUVA or corticosteroids. The recurrence-free survival of 2 out of 4 patients with early stage disease (I-IIA) up to 93 month shows the potentially curative character of the treatment.

Adult↗
PubMed1995

Stand-by treatment of suspected malaria in travellers.

Travellers to malarious areas are increasingly advised to carry an emergency medication for self-treatment of suspected malaria in absence of medical attention. However, no data are available so far how travellers cope with self-diagnosis and stand by treatment (SBT). We therefore investigated the frequency, circumstances and outcome of emergency self-treatment for suspected malaria in German travellers. 3434 travellers were recruited for an open prospective study by 28 different travel clinics in Germany. 2867 travellers (90.1%) who returned questionnaires after their journey were analyzed. 40 travellers (1.4%) reported about SBT during their journey. Significant Plasmodium falciparum antibody levels could be demonstrated in only 4 of 37 SBT users (10.4%). In another 127 travellers with febrile episodes but without SBT use, no malaria was indicated by follow-up and/or serology.

Adult↗
PubMed1993

Patency and morphology of fibrous polyurethane vascular prostheses implanted in the femoral artery of dogs after seeding with subcultivated endothelial cells.

A cell culture line was established from enzymatically-derived canine jugular endothelial cells and further cultured. Whenever sufficient cells were present, fibrous polyurethane vascular prostheses, impregnated with gelatin and coated with fibronectin, were seeded with 4.8 x 10(5)/cm2 cells, sufficient to establish a confluent monolayer, and implanted in the femoral arteries of 16 dogs. A non-seeded prosthesis on the contralateral side served as control. Eight dogs received antiplatelet aggregation medication: 250 mg aspirin together with 25 mg dipyridamole, orally three times daily, starting 2 weeks prior to the implantation operation and continued for the duration of the experiment. Results show that in the non-medicated dogs all control prostheses become occluded within 3 weeks after implantation, whereas five out of eight seeded prostheses remained patent. In the medicated group, two out of eight control prostheses occluded and all seeded prostheses remained patent. Scanning and light microscopy revealed that seeded prostheses were completely lined with endothelial cells (Factor VIII positive stain) week 3 (n = 3) and 12 (n = 3) after implantation, while endothelialisation in control prostheses had advanced only 5 mm into the prostheses in 12 weeks. Two dogs of each group were included in long-term patency studies. We conclude that prostheses seeded with a confluent monolayer of endothelial cells result in superior patency rates for both medicated and non-medicated dogs. No immunological reaction against the (allogeneic) seeded endothelial cells were noted.

Anastomosis, Surgical↗
PubMed1992

Seeding of enzymatically derived and subcultivated canine endothelial cells on fibrous polyurethane vascular prostheses.

Fibrous polyurethane (FPU) prostheses with or without fibronectin coating and gelatin impregnation and FPU prostheses with or without fibronectin coating were seeded with 4.8 x 10(5) subcultivated dog endothelial cells per cm2 prosthesis. Expanded polytetrafluoroethylene (ePTFE) prostheses with and without fibronectin coating served as controls. The numbers of cells retained on uncoated polyurethane prostheses were minimal but increased with fibronectin coating and/or gelatin impregnation. Adhering cells were predominantly round in shape and few cells were seen stretched over the prosthetic fibres. Optimum numbers of cells were found in prostheses impregnated with gelatin and coated with fibronectin, where almost all the cells were stretched forming a confluent monolayer. In ePTFE prostheses only minimal numbers of cells were retained but in the fibronectin-coated prostheses a high cell count was noted. Gelatin-impregnated and fibronectin-coated FPU prostheses, as well as ePTFE prostheses coated with fibronectin, were additionally perfused in vitro after seeding under nearly physiological conditions for 1 h. Cells in the FPU prostheses were still present after perfusion, whereas all the cells in the ePTFE prostheses were lost from the inner surface. It is concluded that FPU prostheses impregnated with gelatin and coated with fibronectin are a suitable substrate for subcultivated endothelial cells to be seeded on. The cells remained at the surface even after 1 h in vitro perfusion with tissue culture medium under nearly physiological conditions. Further research including in vivo implantations is indicated.

Animals↗
PubMed1991

Failure to obtain long-term patency after implantation of fibrous polyurethane prostheses in the carotid arteries of rabbits.

Fibrous polyurethane prostheses were implanted in the carotid arteries and aortae of New Zealand white (NZW) and Chinchilla (CHIN) rabbits. No immediate post-implantation patency was obtained after implantation in the carotid arteries in NZW rabbits. In CHIN rabbits patency up to 1 week was obtained after carotid implantation. Attempts to increase patency rates by administration of 20 mg/kg body weight/day of both dipyridamol (DIP) and acetyl-salicylic acid (ASA) p.o., starting the week before implantation, had an adverse effect; prostheses became occluded within a few hours after implantation. Coagulation tests (Lee and White, Am J Med Sci 145:495-503, 1913) carried out with blood drawn from CHIN rabbits revealed hypercoaguability after administration of either 10 or 20 mg/kg body weight/day of both DIP and ASA compared to pre-medication values. Prostheses implanted in the aortae of both strains remained patent without anti-platelet-aggregation therapy for a 3-month observation period. It is concluded that in the NZW rabbit carotid implantation was not successful due to severe spasmic reactions and that in CHIN rabbits only very short-term patency could be obtained both with and without administration of 10 or 20 mg/kg body weight/day medication DIP and ASA.

Animals↗
PubMed1989

[The pathogenic effect of human immunodeficiency virus. Molecular biological results].

Recent data suggest that the pathogenicity of HIV is mediated by the production of metabolised viral components which act as hormones. In particular the replication and maturation of T-lymphocytes, and the cellular interaction of immunocompetent cells and nerve cells are affected. The recognition of HIV by the immune system and consequently also the progression of the disease, is influenced by the HLA-type (DR-1) of the infected person. Replication of HIV may be accelerated by the simultaneous presence of other viruses (i.e. cytomegalovirus). So-called apathogenic, attenuated HIV variants have been described.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Neointima formation in expanded polytetrafluoroethylene vascular grafts with different fibril lengths following implantation in the rat aorta.

Expanded polytetrafluoroethylene (PTFE) prostheses with fibril lengths of 30 and 60 microns were implanted in the rat infrarenal aorta. Sequential scanning electron and light microscopic studies of the prostheses after implantation demonstrated a different pattern of endothelialization. Prostheses with a fibril length of 60 microns had a continuous multilayered neointima at week 25 postimplantation, whereas prostheses with a 30-microns fibril length had a discontinuous and single layer of endothelium after the same interval. It was concluded, therefore, that a prerequisite for the development of a lining in a vascular prosthesis is for the inner surface of the prosthesis to have adequate pores for effective anchoring of the invading endothelioid cells. Expanded PTFE prostheses with an internodular distance of 60 microns provided sufficient anchoring possibilities for invading endothelioid cells to form a continuous neointima.

Actin Cytoskeleton↗
PubMed1989

Auxiliary liver transplantation in jaundiced rats with UDP-glucuronyltransferase deficiency and defective hepatobiliary transport.

In this study auxiliary liver transplantation (ALT) has been tested as a means of correcting the UDP-glucuronyltransferase deficiency in Gunn rats and the UDP-glucuronyltransferase deficiency and impaired hepatobiliary bilirubin transport in double mutant rats. In both groups serum bilirubin normalized and remained low until the end of the study at 12 weeks after transplantation in 4 out of 6 rats. Excretion of 99mTc-HIDA in non-transplanted double mutants was considerably slower than in Gunn rats (kel 0.9 x 10(-3) versus 4.3 x 10(-3) s-1). HIDA excretion by transplants in double mutants and Gunn rats was about equal (kel 1.6 x 10(-3) and 1.1 x 10(-3) s-1). Experiments with bile duct-cannulated transplants showed that in double mutants bile flow, bile acid and bilirubin excretion was 2-4 times higher than in Gunn rats. This study shows that auxiliary liver transplants can conjugate and excrete bilirubin when one of these or both functions are lacking in the recipient's liver.

Animals↗