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F Allemann

Publications and source records attributed to F Allemann.

14 recordsLinked to original sources
PubMed2001

Effects of medium perfusion on matrix production by bovine chondrocytes in three-dimensional collagen sponges.

Various culture systems have been used for examining the anabolic and catabolic functions of isolated chondrocytes as well as for tissue engineering purposes. Perfusion or frequent medium change is beneficial for three-dimensional (3D) cultures of many cell types. In this study, bovine articular chondrocytes (bACs) were grown in 3D collagen sponges with or without medium perfusion (0.33 mL/min) for up to 15 days. The influence of medium perfusion was evaluated using markers of cartilage matrix accumulation, synthesis, and gene expression. Metachromatic matrix, collagen type II, and hyaluronan accumulated around the cells within the collagen sponges. Sulfated glycosaminoglycans (S-GAGs) that accumulated in the sponge exposed to nonperfused control were 130% of that in the perfused sponge at day 7. S-GAG accumulation after 15 days in the nonperfused control was 230% more than at day 7 (p < 0.01). (35)S-sulfate incorporation during the final 18 h of culture in the sponge exposed to nonperfusion was 180% greater than that in the perfused sponge (p < 0.01). Quantitative analyses show that at day 7, aggrecan and collagen type II gene expression were 350% and 240% greater, respectively, in the nonperfused culture than in the perfused one. These results indicate that perfused conditions that are beneficial for other cell types inhibit chondrogenesis by articular chondrocytes in 3D culture.

Animals↗
PubMed2001

Effects of hyaluronan on engineered articular cartilage extracellular matrix gene expression in 3-dimensional collagen scaffolds.

Hyaluronan (HA) is a component of cartilage matrix with known effects on chondrocytes. We tested the effects of adding HA to 3-dimensional (3-D) collagen. sponges on chondrocyte function in vitro. Bovine articular chondrocytes isolated by collagenase digestion were injected into either collagen or HA/collagen scaffolds comprising different amounts of HA (2, 5, 10, and 14% w/w). Expression of aggrecan and type II collagen genes was measured by gene-specific quantitative competitive reverse transcriptase-polymerase chain reactions, and the extracellular matrix was estimated by histomorphometrical analyses. After 7-day culture, the chondrocytes in 2% (w/w) HA sponges expressed fourfold more mRNA transcripts for type II collagen (p = 0.002) and twofold more mRNA transcripts for aggrecan (p = 0.022) than in control collagen sponges. Furthermore, there was 45% more extracellular matrix in 2% (w/w) HA sponges and 43% less matrix in the 10% (w/w) HA sponges compared with plain collagen sponges (p > 0.05). In sum, a small amount of HA in 3-D collagen scaffolds enhanced chondrogenesis, but a greater amount was inhibitory. This 3-D system represents a novel tool to identify mechanisms by which extracellular matrix molecules influence chondrocyte function. Further, these results show the potential for modifying scaffolds to improve production of engineered cartilage for in vivo applications.

Aggrecans↗
PubMed1999

Ultrasound scans done by surgeons for patients with acute abdominal pain: a prospective study.

OBJECTIVE: To evaluate the routine use of abdominal ultrasonography (US) in patients admitted to the surgical emergency unit with acute abdominal pain. DESIGN: Prospective study with a three-step evaluation of patients over a 12-month period. SETTING: University hospital, Switzerland. SUBJECTS: 496 patients (male/female = 234/262; mean age 45 years) who presented with acute abdominal pain. INTERVENTIONS: Every patient underwent routine investigations and had an abdominal US by the attending surgeon. MAIN OUTCOME MEASURES: Clinical diagnosis, post-ultrasonography diagnosis and final diagnosis. RESULTS: US improved the correct diagnostic rate from 348 (70%) to 414 (83%). The diagnostic accuracy for acute appendicitis and biliary tract disease improved after US from 455 (92%) to 488 (98%) and from 463 (93%) to 490 (99%), respectively; the corresponding sensitivities and specificities were 91% and 99% and 94% and 99%. CONCLUSIONS: Ultrasonography should be part of routine surgical investigation and should be mastered and used by surgeons.

Abdomen, Acute↗
PubMed1997

Non-small cell lung cancer: nodal staging with FDG PET versus CT with correlative lymph node mapping and sampling.

PURPOSE: To prospectively compare the accuracy of positron emission tomography (PET) with 2-[fluorine-18] fluoro-2-deoxy-D-glucose (FDG) with that of computed tomography (CT) in the nodal staging of non-small cell lung cancer. MATERIALS AND METHODS: PET and contrast material-enhanced CT were performed in 47 patients suspected of having or with newly diagnosed non-small cell lung cancer. Each imaging study was evaluated separately, and nodal stations were localized according to the American Thoracic Society mapping system. Extensive lymph node sampling (599 nodes from 191 nodal stations) of the ipsi- and contralateral tracheobronchial and mediastinal nodal stations was performed at thoracotomy and/or mediastinoscopy. Imaging findings were correlated with histopathologic staging results. RESULTS: The sensitivity of PET and CT was 89% and 57%, respectively, for the staging of N2 or N3 disease in mediastinal nodes; specificity was 99% and 94%, respectively; positive predictive value was 96% and 76%, respectively; negative predictive value was 97% and 87%, respectively; and accuracy was 96% and 85%, respectively. In assigning the correct N stage, PET was correct in 96% and CT in 79% of cases. CONCLUSION: PET with FDG appears to be superior to CT for nodal staging of non-small cell lung cancer.

Adult↗
PubMed1981

[The clinical significance of post-term pregnancy after prospective determination of delivery date (author's transl)].

From 1978 to 1980, 3300 patients had their delivery terms prospectively determined by ultrasonic measuring the first half of pregnancy. - 18.4% had a pregnancy of 281-293 days. Post-terms were found in 1.5%. - Care during pregnancy followed a standardised scheme, beginning on the 281st day. Statistical evaluation of all delivery terms shows an asymmetrical Gaussian distribution. In pregnancies up to 293 days abnormal CTG was found in 7.7%, a prepathological, resp. pathological oxytocin sensitivity test observed in 1.5%. With frequent parallel CTG-checks, amnioscopy is of lesser clinical relevance. Deliveries by forceps or vacuum extraction as well as caesarian sections were not more frequent than in a 280-days-term population. No higher perinatal mortality was observed. - In post-terms meconium was found sub partu in 31.4%. The rate of caesarian sections in post-terms shows an increase to 19.6%, but only to 10.5% in prolonged terms. 1 min. post partum the newborns show a slightly accentuated clinical depression (Apgar 4-6) compared with the control group. However, 5 min. post partum Apgar figures as well as umbilical arterial ph indicate no significant difference. No occurrence of perinatal mortality was registered. With appropriate control (resp. CTG) and management of delivery, higher risks are not to be anticipated for mothers and newborns.

Apgar Score↗
PubMed1980

[Idiopathic varicocele with special reference to childhood and adolescence].

In the past 20 years, we have treated 28 patients with idiopathic varicocele. The cases are described and the literature is reviewed in relation to clinical presentation and treatment. Since there is a correlation between varicocele and sub-fertility early surgical treatment is advocated for children and adolescents. The surgical approach described by Ivanissevich with an inguinal approach and high ligation of the testicularis vein is preferred and this allows access for associated conditions which we found in one third of our patients.

Adolescent↗