Biomedical subjects

B Hammer

Publications and source records attributed to B Hammer.

At least 55 records · Page 3Linked to original sources

PubMed2001

[Fractures of the edentulous atrophic mandible. Fracture management and complications].

BACKGROUND: With increasing atrophy, fractures of the edentulous mandible tend to have a higher incidence of nonunion. However, the connection between disturbances of bony consolidation and inadequate primary stability is often insufficiently discussed. FIXATION: Rigid internal fixation with 2.7 or now 2.4 AO compression and reconstruction plates is a safe procedure to achieve short-term rehabilitation in the mostly elderly patients by ensuring immediate function without intermaxillary fixation. With increasing atrophy, our concept suggests the use of stronger plates and fixation of screws in safe bony regions far from the fracture site. RESULTS AND DISCUSSION: This study reports the results of treatment of 40 fractures of the edentulous mandible in 25 patients from 1979 until 1996: 38 fractures (95%) showed primary healing, and only 1 nonunion was revealed after fracture of the plate. The criteria for choice of plates are discussed as well as fracture exposure and the question of primary and secondary bone grafting.

Adult↗

PubMed2001

Endoscopically assisted Le Fort I osteotomy.

OBJECTIVES: A new technique of the Le Fort I osteotomy using endoscopic techniques through limited approaches has been evaluated. PATIENTS: This technique was first carried out successfully in a study on six cadavers. Thereafter we performed endoscopically assisted Le Fort l osteotomy in two patients. METHODS: Four vertical incisions were used in the vestibule (paranasally and posteriorly) as approaches. The endoscope allowed direct visualization of the osteotomy of the maxilla including the pterygomaxillary junction. The osteotomies could be accomplished with a straight 4 mm osteotome for medial and lateral antral walls and nasal septum and a curved osteotome for the pterygomaxillary junction. RESULTS: The procedures were successful. The descending palatal arteries could be preserved in all cases as a result of endoscopic control. Rigid fixation of the downfractured maxillae was carried out using self-drilling titanium screws and plates. CONCLUSION: Endoscopic visualization allowed safe osteotomy of the medial antral wall preserving the descending palatal artery in all cases and hence less bleeding. Postoperative oedema and swelling in the two clinical cases was definitely reduced when compared with the conventional technique. The time needed for these first two clinical cases was approximately 1 h 30 min, i.e., about 30 min more than with the open technique. Further experience and experimental work, and refinements in technique will help to improve this procedure in its clinical application.

Adult↗

PubMed2001

Repair of composite zygomatico-maxillary defects with free bone grafts and free vascularized tissue transfer.

INTRODUCTION: Three-dimensional repair of the zygomatico-maxillary defect calls for an elaborate technique to achieve facial symmetry and correct globe position. We present a technique, which combines the use of a free vascularized soft tissue flap and free bone grafts for repair of composite zygomatico-maxillary defects. PATIENTS: Three patients that underwent radical resection of the maxilla and the zygoma have undergone facial reconstruction using this technique. The mean follow up was 9 months. METHODS: The key points of this technique are: (1) precise reconstruction of the zygomatico-maxillary complex including the orbit; (2) creation of a skeletal framework for canthopexy and suspension of the free flap; (3) repair of through-and-through soft tissue defects with a folded musculocutaneous free flap; and (4) simultaneous harvesting and reconstruction using two surgical teams to reduce the duration of surgery. RESULTS: Reconstruction of the zygomatico-maxillary complex could be successfully accomplished in a single surgical procedure. CONCLUSION: This paper presents a method of repairing zygomatico-maxillary defects with free bone grafts and vascularized soft tissue. However, this concept has yet to be reviewed in the long term.

Aged↗

PubMed2000

Dynamics of high-barrier surface reactions: laser-assisted associative desorption of N2 from Ru(0001)

We have determined the dynamics and energetics of associative desorption of N2 from Ru(0001) using both an experimental technique, laser-assisted associative desorption, and density functional calculations. These show that N2 is preferentially desorbed into very high vibrational states and that the barriers between gas phase N2 and adsorbed N atoms increase from 2 to >3 eV with increasing N coverage on the surface. This experimental technique is found to be quite insensitive to low barrier steps and defects which complicate interpretations from other methods of studying high-barrier surface reactions.

Journal Article↗

PubMed2000

Catalytic concepts for the enantioselective synthesis of alpha-amino and alpha-hydroxy phosphonates.

The enantioselective synthesis of alpha-amino- and alpha-hydroxy phosphonates by catalytic processes has attracted considerable interest in the last few years, not least because of the pharmaceutical interest in such compounds. This article contains a compilation of the asymmetric synthesis methods developed to date. The described synthetic routes are based on different catalytic concepts, namely, hydrogenation, reductions, dihydroxylation, aminohydroxylation, and hydrophosphonylation.

Amino Acids↗

PubMed2000

[New possibilities for reconstructing extensive jaw defects with prefabricated microvascular fibula transplants and ITI implants].

The reconstruction of extensive jaw defects is frequently only possible with microvascular bone flaps. Here we are presenting an operative technique using prefabricated fibular flaps and osseointegrated implants. In a first operation, the fibula is prepared with implants, split skin graft, and a nonresorbable membrane. The jaw defect is reconstructed 6 weeks later and can be treated directly with a prosthesis thanks to osseointegrated implants. The technique is described with reference to 5 patients already operated according to this technique and the initial findings are evaluated.

Adult↗

PubMed2000

Manipulation of callus after linear distraction: a "lifeboat" or an alternative to multivectorial distraction osteogenesis of the mandible?

Despite impressive results, distraction osteogenesis of the mandible is still compromised by difficulties with vector control. Because of the action of the masticatory muscles, the gonion angle has the tendency to open, resulting in an open bite. We report two patients, aged 10 and 12 years, who developed a severe open bite during mandibular distraction. As a salvage procedure, manual shaping of the soft regenerate was done immediately after distraction. Uneventful bony consolidation was observed, which resulted in anatomically shaped gonion angles. The fact that a regenerate created by distraction osteogenesis can be molded to virtually any shape offers interesting perspectives for the correction of complex mandibular deformities.

Bony Callus↗

PubMed1999

Utility of abdominal sonography in patients with idiopathic deep vein thrombosis.

PURPOSE: Studies have confirmed an association between idiopathic deep vein thrombosis (DVT) and malignant tumors. We assessed the usefulness of routine abdominal sonography in patients with idiopathic DVT to detect malignant tumors and other relevant findings. METHODS: We retrospectively analyzed abdominal sonograms and records from 135 consecutive patients with confirmed idiopathic DVT and interviewed patients and their physicians during the follow-up period (mean, 30 months). Malignancy and other clinically relevant findings determined by sonography were tabulated, and the cost of each malignancy detected by abdominal sonography in this study was calculated. RESULTS: Malignant tumors were found in 14 patients (10%), 7 by routine abdominal sonography, 3 by other means during hospitalization, and 4 during the follow-up period. Other clinically relevant findings detected by routine abdominal sonography were found in 33 patients (24%). The estimated cost of discovering malignancy by using screening abdominal sonography was approximately US$3,000/malignancy. CONCLUSIONS: Abdominal sonography was useful in detecting a variety of clinically relevant findings in addition to half of the malignant tumors found in our study.

Abdomen↗

PubMed1999

Repair of complex orbital fractures: technical problems, state-of-the-art solutions and future perspectives.

Within the wide range of severity of orbital fractures, the small group of complex fractures causes most of the sequelae. Therefore identification of severe injuries and adequate treatment is of major importance. The introduction of craniofacial techniques made possible a wide exposure of even large orbital wall defects and their reconstruction by grafts. In spite of significant progresses, repair of complex orbital wall defects remains a difficult surgical problem even for the experienced. This paper outlines the specific technical problems concerning surgical anatomy, exposure and defect reconstruction of this type of injuries. A number of new developments providing interesting future perspectives for orbital wall reconstruction such as intraoperative navigation, endoscopic techniques and new materials are discussed.

Animals↗

PubMed1998

[Chronic giardiasis with intestinal dwarfism and delayed puberty in immunoglobulin deficiency syndrome: complete catch-up growth after therapy].

A 10-year-old, previously healthy Swiss boy suffered from repeated episodes of watery diarrhea for some months following a summer camp holiday. No etiology was found, and except for symptomatic treatment no other therapy was necessary. Five years later he was investigated because of growth failure, with a bone age of 11.5 years, but the correct diagnosis was not established. Only when he was reinvestigated at the age of 20 years, because of persistent growth failure and a bone age of 14 years, were Giardia lamblia trophozoites seen microscopically on the surface of duodenal mucosa biopsy specimens. At the same time dysgammaglobulinemia was detected which may have predisposed the gastrointestinal tract to chronic giardiasis. After a 10-day course of metronidazole the patient experienced catch-up growth and completed his pubertal development. The dysgammaglobulinemia persisted after therapy. This case showed that in patients with intestinal growth failure, catch-up growth and completion of pubertal development are possible even after the age of 20 years if nutritional supply is sufficient. Bone age determinations serve to indicate remaining growth potential.

Adolescent↗

PubMed1998

Design of a surface alloy catalyst for steam reforming

Detailed studies of elementary chemical processes on well-characterized single crystal surfaces have contributed substantially to the understanding of heterogeneous catalysis. Insight into the structure of surface alloys combined with an understanding of the relation between the surface composition and reactivity is shown to lead directly to new ideas for catalyst design. The feasibility of such an approach is illustrated by the synthesis, characterization, and tests of a high-surface area gold-nickel catalyst for steam reforming.

Journal Article↗

PubMed1998

[Experimental reconstruction of the sheep orbit with biodegradable implants].

In a complex animal model in sheep, polydioxanone (PDS) and polylactic membranes were used for the reconstruction of large orbital-wall defects. In a long-term experiment over 1 year, polylactic implants alone showed the best performance as compared with combinations involving autogenous bone grafts and titanium miniplate fixation. As soon as these polylactic implants are approved for human surgery, they will be used to solve the still challenging problem of anatomical reconstruction of large comminuted fractures of more than one orbital wall.

Animals↗

PubMed1998

Atypical, cytoplasmic and perinuclear anti-neutrophil cytoplasmic antibodies in patients with inflammatory bowel disease.

Atypical, cytoplasmic and perinuclear anti-neutrophil cytoplasmic antibodies (x-, c- and pANCA, respectively) are associated with a variety of inflammatory diseases, including inflammatory bowel disease (IBD). Anti-neutrophil cytoplasmic antibodies are more common in patients with ulcerative colitis (UC) than in patients with Crohn's disease (CD). Most publications only refer to p- and cANCA in relation to IBD. We have prospectively evaluated the reactivity of sera from 58 patients with IBD and 10 healthy controls against human neutrophils with emphasis on the distinction of the ANCA types. The sera were incubated with ethanol- and formaldehyde-fixed granulocytes to differentiate between c-, p- and xANCA. The results showed that 10 of 24 patients with UC were positive for ANCA, whereas only one of 34 patients with CD was ANCA positive. These results correspond to a sensitivity of 42%, a specificity of 97%, a negative predictive value of 91% and a positive predictive value of 75% in UC. Of the 11 ANCA-positive sera, two showed a cytoplasmic staining pattern, three showed a perinuclear and six an atypical staining pattern. The disease activity was not correlated to either the ANCA titre or to the presence of ANCA in the serum. In conclusion, ANCA are of limited value in differentiating between UC and CD. Because the majority of ANCA in patients with IBD are xANCA, these ANCA should be explored by not only incubating on ethanol-fixed granulocytes, but also on formaldehyde-fixed granulocytes.

Adolescent↗

PubMed1997

Osteosynthesis of condylar neck fractures: a review of 30 patients.

This article reviews 31 condylar neck fractures in 30 patients stabilized with different types of plates with emphasis on complications associated with different types of plates. Indications for stabilization were predominantly bilateral fractures, shortening of the ascending ramus due to lack of occlusal buttressing and condylar neck fractures associated with panfacial fractures. Stabilization was achieved with a single (23 fractures) or a double adaptation miniplate (4 fractures), a 2.4 mm plate (2 fractures) or a TMJ prosthesis (2 fractures). Eight fractures exhibited complications requiring reoperation (4 plate fractures, 3 cases of screw loosening associated with infection, 1 malposition). Complications occurred exclusively in the fractures stabilized with a single adaptation miniplate. Recommendations for stabilization, therefore, include a double miniplate, a 2.4 plate, a minidynamic compression plate (finger-plate) or a 2.0 mandibular-miniplate. Screws are preferably placed bicortically.

Adolescent↗

PubMed1997

Diffuse abdominal pain, nausea and vomiting due to retroperitoneal fibrosis: a rare but often missed diagnosis.

Retroperitoneal fibrosis is a rare chronic inflammatory disease usually involving the ureters, retroperitoneal vessels and nerves; however, any intestinal organ may also be involved. In recent years, a few successful immunosuppressive treatments of this disease have been described and surgery can, therefore, probably be avoided in most cases. We report here on a case of secondary retroperitoneal fibrosis with compression and midline deviation of the ureters and impaired renal function which was probably caused by ergotamine abuse because of migraine. The patient complained of diffuse abdominal pain, nausea and vomiting. After immunosuppressive treatment with azathioprine and prednisone for a year, we observed a complete resolution of the retroperitoneal mass on computed tomography, although renal function remained impaired. Eleven months after the cessation of treatment, the patient had not relapsed.

Abdominal Pain↗

PubMed1997

Significance of histologic criteria for the management of patients with malignant colorectal polyps and polypectomy.

BACKGROUND: The management of invasive cancer in colorectal polyps (malignant polyps) is controversial, particularly with regard to the different sets of histologic criteria for deciding whether malignant colorectal polyps should be treated by polypectomy alone or be followed by surgical resection. We report on the outcome of patients in accordance with the histologic assessment of their malignant polyps. METHODS: Malignant polyps were defined as having favourable histology (free margin, grade I or II, and no angiolymphatic invasion) or unfavorable histology (no free margin, grade III, or angiolymphatic invasion). Malignant polyps with favourable histology were treated by endoscopic polypectomy alone, whereas further therapy was recommended for malignant polyps with unfavourable histology. Residual cancer in a resection specimen and local or metastatic recurrence during the follow-up period (mean, 60 months; range, 12 - 120) were defined as adverse outcome. RESULTS: Thirty-seven malignant polyps were detected in 35 (0.5%) of 6605 patients. Five of these 35 patients were treated by primary bowel resection and analysed separately. In the other 30 patients the following unfavourable histologic signs were detected in 20 (62.5%) of 32 malignant polyps; no free margin in 16, grade III in 1, and angiolymphatic invasion in 3 polyps. Twelve polyps with favourable histology had no adverse outcome; in contrast, 5 of 20 polyps with unfavourable histology had an average outcome (P < 0.05). CONCLUSIONS: Locally excised malignant polyps without unfavourable histologic signs may not need further surgical treatment; for all other malignant polyps an ensuing bowel resection is recommended.

Adult↗

PubMed1997

Self-expanding metal stents in malignant esophageal obstruction: a comparison between two stent types.

OBJECTIVES: Self-expanding metal stents are a promising alternative in the palliation of malignant esophageal obstruction, but the relative value of different stent types is not well established. METHODS: During a 3-year enrollment period in four different centers, 82 consecutive patients with malignant dysphagia without tumor recurrence after surgery or esophagorespiratory fistulas received either an uncovered Wallstent (44 patients) or a knitted nitinol stent (38 patients). RESULTS: Age (median: 79 yr), sex (F:M = 33:67), dysphagia score (median: 3), Karnofsky score (median: 53), body mass index (median: 19), type of pretreatment, tumor stage, stricture length (median: 5.4 cm), and stricture location were comparable in both stent groups. After stent placement, median dysphagia score improved markedly in both groups by two points. Procedure-related mortality (16 vs 0%; p < 0.01), early complication rate (32 vs 8%; p < 0.01), and severe persistent pain after stent placement (23 vs 0%; p < 0.002) were higher in the Wallstent compared with the knitted nitinol stent group. In contrast, stent dysfunction (7 vs 32%; p < 0.005), reintervention rate (9 vs 34%; p < 0.005), and costs were lower in the Wallstent compared with the nitinol stent group. CONCLUSIONS: In malignant esophageal obstruction, both stents markedly improved dysphagia. Uncovered Wallstents seem to cause more early severe complications than knitted nitinol stents. In contrast, stent dysfunction, reintervention rate, and costs appear to be higher in the nitinol stent group.

Adult↗

PubMed1997

Study with two prokinetics in functional dyspepsia and GORD: domperidone vs. cisapride.

The HT4-agonist Cisapride (CIS) and the peripheral D2-antagonist Domperidone (DOMP) have distinct prokinetic actions. We compared their clinical efficacy in 127 dyspeptic patients. Patients with upper abdominal complaints of > 1 month duration, who had a normal UGE were allocated to the REFLUX-group (RG), (predominance of heartburn, acid regurgitation or retrosternal pain) or if devoid of this specific symptomatology to the DYSPEPSIA-group (DG) In a double-blind randomised fashion and allocated to 10 mg CIS or 20 mg DOMP qid (RG) or tid (DG) for 1 month and followed-up for further 2 months. In RG (N = 43, p < 0.05) the response rates were clearly in favour of CIS, but not in DG (N = 84). In RG DOMP was more effective against nausea. The benefit of both therapies was largely maintained in the follow-up period. Cisapride and domperidone were effective in the treatment of dyspepsia. Cisapride was more effective than domperidone in the REFLUX-Group.

Adult↗