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Biomedical subjects

H K Mandelkow

Publications and source records attributed to H K Mandelkow.

5 recordsLinked to original sources

Accurate diagnosis of acute appendicitis: a retrospective and prospective analysis of 686 patients.

OBJECTIVE: To formulate a score system that would make the preoperative diagnosis of acute appendicitis more accurate. DESIGN: Retrospective then prospective study. SETTING: City University Hospital. SUBJECTS: 536 patients who had their appendixes removed between 1981 and 1986 (retrospective study), and 150 consecutive patients admitted with a presumptive diagnosis of appendicitis between 1987 and 1988 (prospective study). MAIN OUTCOME MEASURES: Correlation between the histological diagnosis of appendicitis and variables representing history, clinical examination, and laboratory investigations. RESULTS: The rate of histologically proven negative appendicectomies in the retrospective series was 40% and in the prospective series 33%. The variables that were thought to be predictive were: male sex, white cell count of greater than 11 x 10(9)/l, history of less than 24 hours with no previous complaints, rebound tenderness, shift of pain from the epigastrium, and localised guarding, but all criteria had low specificities and sensitivities when applied prospectively, and combining the scores did not improve them. CONCLUSION: The accurate diagnosis of appendicitis depends largely on the experience of the surgeon and is not improved by the application of a score system that includes the above variables.

Acute Disease↗

Bone transplantation.

According to one principle of surgery, the transplantation of vital tissue is the best method of reconstructing a defect. Because of absent immunologic reactions, high osteogenic potency, and preserved stability, transplantation of autogenous bone shows the best results. Necrosis of transplanted bone, leading inevitably to absorption and remodeling of the graft, can be avoided if microsurgically vascularized autogenous bone segments are transferred. Disadvantages are the low availability and the necessity of additional operations. As an alternative, deep-frozen allogeneic bone is used. However, this kind of bone shows delayed incorporation based on cellular and humoral immune reactions, and it is also installed into the host bed after overcoming the immune barrier. The risk of microbiological contamination or transmission of unrecognized germs such as HIV is a cause of great expense in bone banking techniques. If one succeeds in reducing (a) the immunologic defense reaction and (b) the risk of infection by sterilization or disinfection without damaging the osteoinductive proteins of bone matrix, the rate of complications can be lowered. Demineralized bone matrix can be used if biomechanical stability is not required. Its ability to induce osteogenesis without a major immune reaction or the risk of transmitting diseases justifies its clinical application. Further intensive research in these areas is unavoidable.

Bone Transplantation↗

[Retro- and prospective studies on the value of clinical and laboratory chemical data in acute appendicitis].

In a retrospective study 536 appendicectomized patients were analyzed, in order to identify anamnestic, clinical and laboratory findings which allow the differentiation between acute and non-acute appendicitis. 150 consecutive patients were studied prospectively, which were referred to our department with a presumptive diagnosis of acute appendicitis. Eight single criteria were found, which exhibited a significantly different frequency in acute and non-acute appendicitis. Each criterion showed a low sensitivity and specificity; a score, which was created by combination of these single criteria also had low sensitivity and specificity. We conclude that the correct indication for appendicectomy highly depends on clinical experience of the surgeon.

Acute Disease↗

[New bone formation following implantation of various hydroxyapatite ceramics. Animal experiment with bore hole models of the sheep tibia].

The aim of this study was to measure new bone formation after implantation of hydroxylapatite ceramic materials compared with autogenous and allogenous cancellous bone implantations. Eight standardised bore holes, each 6 mm in diameter, were drilled in the left medial tibia of each of seven merino sheep. Seven of these holes were filled with hydroxylapatite ceramic materials: Bio-Oss, Pyrost, autogenous and deep frozen allogenous spongiosa in various sequences. The empty hole was used for comparison. Results were evaluated after fluorescent marking with calcein green 6 weeks postoperatively. The extent of new bone formation was determined by means of fluorescence microscopy, microradiography and histological sections and quantified by means of an automatic surface-measuring programme. Whilst implantation of autogenous spongiosa resulted in almost complete slicing of the defect, the holes filled with hydroxylapatite ceramic materials showed no significant difference from the empty defect. We conclude that this purely inorganic material cannot stimulate new bone formation.

Animals↗