Tissue engineering of bone for mandibular augmentation in immunocompetent minipigs: preliminary study.

Large mandibular defects caused by trauma, infection or resection of a tumour are still a major problem for plastic and maxillofacial surgeons. The modern concept of tissue engineering combines the osteoinductive effects of osteogenic cells with a suitable scaffold structure to promote differentiation of osteoblasts and optimal matrix production. Critical size mandibular bone defects were therefore made to investigate the osteogenic potential of periosteal cells and a bioabsorbable polymer fleece (Ethisorb 510) in minipigs. Periosteal cells were isolated from four minipigs, expanded in vitro and seeded with fibrin glue into Ethisorb 510 fleeces. Tissue constructs were used to repair critical size mandibular defects and compared with two minipigs with untreated bone defects. Bone healing was evaluated after 90 and 180 days by radiographs and a histological scoring system. The radiographs showed increased radiodensity of defects filled with the cell-fibrin-fleece-constructs compared with the untreated control group after 90 and 180 days in vivo. The defects repaired by the cell-fibrin-scaffolds (180 days in vivo) obtained the highest histological mean score 2.9 (range 2-3), while defects filled by cell-fibrin-scaffolds (90 days in vivo) achieved a mean score of 2.1 (range 2-3). In contrast, the control group (n = 2) scored 1 and 2. The results show that a combination of periosteal cells and polymer fleeces may be a promising approach for clinical mandibular augmentation.     

Radiation therapy in proliferative vitreoretinopathy

In a prospective study of the effect of postoperative radiation therapy for the prevention of reproliferation of membranes and recurrent proliferative vitreoretinopathy (PVR) two similar groups of patients with retinal detachment and PVR grade D1 to D3 in one eye were compared. Half the eyes (30) received a total dose of 3000 cGy after surgery; the other half remained untreated. After a followup of 6 months and 14 months or more (maximum 36 months) the anatomical and functional results of each group were compared. After 6 months in the unirradiated group 57% (17/30) remained attached and 43% (13/30) had detached again. In the irradiated group 63% (19/30) were attached and 37% (11/30) had detached. However, there was no statistically significant difference between the two groups (P=0.479, Fisher's Exact Test). After 14 months the number of cured and uncured eyes remained the same in the unirradiated group, while in four of the eyes in the irradiated group a later onset of reproliferation and detachment occurred (after 7, 8, 12 and 14 months, respectively). A final cure rate of 57% (17/30) was achieved in the unirradiated group and a 50% (15/30) cure rate in the irradiated group. Thus the failure rate was 43% (13/30) in the unirradiated group and 50% (15/30) in the irradiated group (P=0.473, Fisher's Exact Test). No side effects from the radiation were observed in any case and no radiation retinopathy occurred during an observation period of up to 3 years. The visual acuity of the cured treated and cured untreated eyes was similar in the two groups. From these results we conclude that immediate radiation treatment does not improve the long-term results and does not reduce the number of reoperations. In a considerable number of treated eyes the onset of reproliferation was delayed from 7 to 14 months, whereas in the untreated group reproliferation was always observed during the first 6 months. A combination of various antiproliferative and antiinflammatory therapies are needed to suppress recurrent PVR after succesful vitreoretinal surgery and to minimize the side effects of these treatments.Presented in part at the XVIIth Meeting of the Club Jules Gonin, 1–6 September 1990, Lausanne     

Macrophage response to microtextured silicone

Seven different silicone surface textures were tested for effect on macrophage spreading and metabolic activity in vitro. Variables of the textured arrays that could modify spreading were determined to be the size, spacing between, depth, density, and orientation of the individual surface events and the roughness of the surfaces. Cells were influenced by the size of the events and the roughness of the surfaces more than any other variables. Cell morphology data, surface area and perimeter, could be divided into discrete regions that correlated well with the size of the events. Cell dimensions on 5μm textures were smallest while those on smooth silicone and glass surfaces were the largest. Surface texture events may be modifying contact guidance of the cells or interacting with specific transmembrane proteins to alter cell shape and function. The mitochondrial activity of cells attached to the textured silicones was determined by measuring the amount of reduced MTT directly through live cells. Cells on polystyrene (PS), 5VP and 8VP textures were metabolically more active than cells on the other textures. PMA was used to stimulate cells on the various textures. PMA-stimulated cells, on the smaller textures, 2VP, 5VP and 5CP, were less active than test cells that were not stimulated. The inability of PMA to stimulate these cells may be due to a structural alteration of protein kinase C. An hypothesis is introduced that includes a possible mechanism of how a micrometre-sized surface texture could modify cell function.     

Recurrent venous thrombosis following free flap surgery: The role of heparin-induced thrombocytopenia

Complications following free tissue transfer have been well established in the literature. Common and rare causes of free flap failure must be addressed by the treating surgeon when microvascular patency is threatened. With the evolution and prevalence of microsurgery, ‘rare’ causes of free flap failure will become increasingly frequent. A high index of suspicion must be established in patients with multiple failed operative interventions. A case of recurrent free flap failure secondary to heparin-induced thrombocytopenia is presented in a patient with a history of squamous cell carcinoma of the floor of the mouth, and a long-standing history of alcohol and tobacco consumption.     

Referral pattern of patients with oral mucosal lesions in The Netherlands

The referral pattern of 140 Dutch patients with oral mucosal lesions, who had been referred to a Department of Oral & Maxillofacial Surgery and Oral Pathology, shows that patients with oral mucosal lesions consult the dentist as often as the family doctor as the first source of help or information. Furthermore, family doctors were much more used to refer patients with oral mucosal disease to medical specialists rather than to the dentist or the oral and maxillofacial surgeon.     

Neuropathy associated with “benign” anti-myelin-associated glycoprotein IgM gammopathy: Clinical,immunological, neurophysiological pathological findings and response to treatment in 33 cases

We studied 33 patients presenting with a peripheral neuropathy associated with non-malignant anti-myelin-associated glycoprotein (MAG) IgM monoclonal gammopathy (MG) in an attempt to delineate their clinical, immunological, electrophysiological and pathological characteristics; we also reviewed our experience concerning long-term follow-up and therapy. Peripheral neuropathy associated with non-malignant anti-MAG IgM MG was observed mostly in males (sex ratio 7.2), and mean age at onset was 67 years (range 46–81). A predominantly sensory pattern was noted in more than 80% of cases, although some patients were affected by a predominantly motor peripheral neuropathy. Although disease progression was slow in most cases, 45% of patients suffered severe disability, and in 2 cases, the patient's death appeared to stem directly from the neuropathy. The electrophysiological findings were indicative of a demyelinating process in 90% of cases, and electron microscopic examination of nerve biopsy specimens demonstrated widening of the myelin lamellae in more than 95% of cases. Most of our patients showed a disappointing response to steroids and chemotherapy or plasma exchanges. Intravenous immune globulin, evaluated in 17 patients, had a transient, mostly subjective effect in 35% and led to a clear-cut improvement in 24% of cases. We did not observe any correlation between the severity of the clinical picture and the anti-sulphoglucuronyl paragloboside antibody titre; in individual cases, clinical improvement occurred without lowering of IgM levels. Although the severity and the rate of progression may greatly vary from patient to patient, the combination of clinical, electrophysiological and pathological features delineates a characteristic pattern in peripheral neuropathy associated with non-malignant anti-MAG IgM MG.     

The role of radio-oncology in the treatment of bronchial cancer

The treatment results obtained in patients with both small and non small cell lung cancer have remained stagnant for years. Therefore, in order to select patients who will have a profit from radiotherapy the indication has to take into account prognostic factors such as tumor stage, extent of resection, patient's age, lymph node status, weight loss and the patient's performance status. Non small cell lung cancer: Postoperative radiotherapy seems to benefit only in patients with hilar or mediastinal lymph node involvement, where a five-year survival rate of up to 30% of cases can be achieved. Postoperative irradiation should not be applied following curative resection and negative lymph node status (R0 N0). In inoperable cases conventional fractionated radiotherapy may definitively have a favourable effect on the patient's survival time, even when the treatment was originally intended to be merely palliative. Only those patients will live five years, who received more than 50 Gy to the hilar and mediastinal nodes and at least 60 Gy to the primary lesion. The volume to be irradiated must include the primary tumor, the ipsilateral and contralateral hilum, the mediastinum, and both supraclavicular regions. If a Pancoast tumor is present, radiotherapy alone obtains a similar result as preoperative irradiation followed by resection. Small cell lung cancer: Radiation treatment of the primary tumor region and the lymph drainage area increases the remission rate by roughly 20% compared with chemotherapy alone, considerably reduces the incidence of local recurrences and exerts a beneficial effect on the survival of the patients. Recently, this has been confirmed by prospectively randomised protocols. Prophylactic brain irradiation has been found to decrease the risk of cerebral metastases to 4-6% in patients affected by limited disease and complete tumor remission under chemotherapy, and to improve the quality of life without, however, showing the benefit on survival time. Future efforts in radiotherapy should be aimed not only at increasing dose intensities but also at developing less toxic treatment modalities to the benefit of the quality of life.     

Isolated and combined effects of prolonged exposures to noise and whole-body vibration on hearing,vision and strain

Summary This study was carried out in order: (1) to examine the effects of isolated and combined prolonged exposures to noise and whole-body vibration on hearing, vision and subjectively experienced strain, and (2) to check the combined effects with repeated exposures. Six male subjects were exposed twice to noise (N) at 92 dBA, whole-body vibration (V) in the Z-axis at 4 Hz and 1.0 ms^–2 rms, and noise and vibration (NV) for 90 min with each condition. Temporary threshold shifts of hearing (TTS) and their integrals (ITTS) were measured at 4, 6, 10, and 12 kHz. Visual acuity was examined by means of a very sensitive test. Cross-modality matching (CMM) of the handgrip force was used to judge the subjectively experienced strain. NV induced a clear tendency of higher TTS and ITTS than N, with several significant differences most pronounced at 10 kHz. With repeated exposures, the effect of NV decreased, while the reactions to N and V remained unchanged. The individual reactions to NV differed. The influence of the duration of exposures on vision depended on the condition; N caused time-dependent changes, whereas V did not. CMM-data increased with the duration of the exposure during V and NV. N was generally judged to be more straining than V; NV caused higher strain than V during the first 30 min of exposure only. Correlations between different effects suggest certain links between them. Additionally, less motivation — daily obtained by a questionnaire — often correlated with higher ITTS during N and NV. The results also illustrate the combined effects on the individual susceptibility, repetition of exposure, the kind of response, and, possibly, the actual psychic state.Abbreviations CMM cross-modality matching - MVC maximum voluntary contraction force - N exposure condition: noise level 92dBA, no whole-body vibration - NV exposure condition: combined exposure to noise with a level of 92 dBA and wholebody vibration with 4 Hz, 1 ms^–2 rms - V exposure condition: whole-body vibration with 4 Hz, 1 ms^–2 rms - TTS temporary threshold shift - ITTS integral of temporary threshold shift - WBV whole-body vibration in the common sense This work was done in the Temporary International Research Team on Combined Effects of Noise and Vibration of the Council of Mutual Economic Assistance of the Socialist Countries. The authors gratefully acknowledge the help and assistance of L.-M. Brumm, Y. Bening, M. Godau, G. Weber, and R. Vizcaino.