Biomedical subjects
M Kon
Publications and source records attributed to M Kon.
Non-decay type fast-setting calcium phosphate cement: setting behaviour in calf serum and its tissue response.
Non-decay type fast-setting calcium phosphate cement (nd-FSCPC) was evaluated in terms of its setting behaviour in calf serum and its tissue response to investigate the feasibility of its clinical use in surgical applications. Non-decay type cements were prepared by adding various amounts of sodium alginate to the liquid phase of base cements, fast-setting calcium phosphate cement (FSCPC) and conventional calcium phosphate cement (c-CPC). Cement pastes were immersed in serum at 37 degrees C immediately after mixing, and decay behaviour, setting time and mechanical strength were measured to evaluate the possibility of their use in surgical applications. Also, nd-FSCPC was implanted into rat subcutaneous tissue for the initial evaluation of biocompatibility of this potential bioactive cement. nd-FSCPC set in approximately 6-7 min in serum, even when the cement paste was immersed in the serum immediately after mixing, whereas c-CPC and FSCPC decayed completely upon immersion. nd-FSCPC transforms to hydroxyapatite (HA) within 24 h and shows a diametral tensile strength of approximately 4-5 MPa. As a result of transformation to HA, nd-FSCPC showed excellent tissue response when implanted subcutaneously in rats. We conclude that nd-FSCPC has good potential value for use in orthopaedics, plastic and reconstructive surgery, and oral and maxillofacial surgery, where the cement is exposed to blood.
Dysfunctional postures of the hand as part of a conversion reaction.
A dysfunctional posture of the hand could be due to an anatomical disorder or a conversion reaction. A conversion reaction implies that an unconscious intrapsychic conflict is expressed in a physical dysfunction. Treatment of dysfunctional postures due to conversion reactions is often difficult, and case reports are used to outline management. The need for a multidisciplinary approach is stressed.
Correction of severe blepharoptosis.
An analysis is made of 81 patients with severe blepharoptosis who underwent correction with autogenous fascia. In case of severe blepharoptosis, which means a levator function of less than 5 mm, correction by levator resection gives insufficient results. Better results are obtained by frontalis suspension, whereby the upper eyelid is connected to the frontalis muscle using fascia lata strips according to Crawford. The operative technique is described in detail. Particular interest has been paid to the width of the vertical lid fissure and symmetry between both upper eyelids after operation. The overall results were rated satisfactory to excellent with an average of 9 mm of postoperative vertical lid fissure. Comparison of the results of unilateral versus bilateral blepharoptosis correction revealed better results in the group of bilateral ptosis correction. In 76% of the bilateral patients, there was an asymmetry of less than 0.5 mm between both palpebral fissures, while in the unilateral group this result was achieved in only 35% of the cases. Symmetry is difficult to achieve in the unilateral group, especially when the vertical lid fissure of the nonptotic eye is 10 mm or more. In these cases, correction of both upper eyelids should be considered. The best time to operate on patients with severe congenital blepharoptosis is around the age of 4 to 5 years, because lagophthalmus after operation is better tolerated and the leg has developed sufficiently to provide an adequate amount of fascia. The correction of severe blepharoptosis by frontalis suspension with autogenous fascia shows a high rate of success and few complications.
Fascia lata suspension of malpositioned ears.
A new technique for the correction of malpositioned ears in congenital or acquired disorders is described. The use of a fascia lata strip makes a rigid fixation of the ear to the pericranium possible without total fixation of the ear in all directions. The configuration of the auricle is not altered, and the scars are inconspicuous.
Auricular hypermobility due to agenesis of the extrinsic muscles.
A patient is presented with complaints of a hypermobile right ear due to agenesis of the superior and posterior auricularis muscles and a thin concha cartilage. Suturing the concha cartilage to the mastoid bone and temporal fascia gave sufficient support of the external ear without creating a gross difference in appearance of both ears.
Pathophysiology and treatment of diabetic diarrhea.
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Camptodactyly caused by an anomalous origin of the flexor digitorum superficialis tendon. Case Report.
A 20 year old man with a progressive flexion contracture of the proximal interphalangeal joint of his right ring finger had an anomalous origin of the flexor digitorum superficialis tendon. After excision of the aberrant flexor tendon the patient had a normal range of movement of the proximal interphalangeal joint.
Oxidative processes and free radical scavengers in ischaemia-reperfusion injury in adipocutaneous flaps: in vitro lipid peroxidation assessment.
An in vitro lipid peroxidation study measuring Schiff base and TBAR formation in homogenates of the fat and skin fractions of epigastric free flaps of DA-rats was performed to determine the role of oxygen-derived free radicals (ODFRs) in the aetiology of ischaemic injury and of ischaemia and reperfusion injury following cold (0-1 degree C) storage. The storage intervals were 0, 48, 72, 96 and 120 h in the study on ischaemic injury and 72 and 96 h in the study on combined ischaemia and reperfusion injury. Reperfusion was accomplished by anastomosing the pedicle vessels of the flap to the femoral vessels of a recipient; the reperfusion period was 15 min. In addition to a control group (C), three experimental groups were created to test the benefit of a preischaemic single passage perfusion with a hypertonic citrate solution (HCA), a pre- and postischaemic treatment with desferrioxamine (DFX) and a pre- and postischaemic treatment with lipoic acid (LA). The susceptibility of homogenates of skin and fat fractions of epigastric free flaps in DA-rats for lipid peroxidation increased significantly whenever the cold (0-1 degree C) ischaemic interval was prolonged from 0 to 72 h. These findings offer circumstantial evidence for the role of ODFRs in the aetiology of ischaemic injury. Following a short reperfusion period after extended periods of cold (0-1 degree C) ischaemia, no significant increase in susceptibility for lipid peroxidation could be found. Furthermore, no unequivocal role in the prevention of ischaemia and/or reperfusion injury by the use of either HCA, or DFX or LA could be found. The exact role of ODFRs in the aetiology of ischaemia-reperfusion injury in this setting remains unclear.
Non-decay type fast-setting calcium phosphate cement: composite with sodium alginate.
Non-decay type fast-setting calcium phosphate cement (nd-FSCPC) was prepared by introducing sodium alginate (0-2.0 wt%) into the liquid phase of FSCPC. nd-FSCPC was stable even when the cement paste was immersed in distilled water immediately after mixing, whereas conventional FSCPC (c-FSCPC) decayed completely within 1 min upon immersion. The setting time of the cement, approximately 5 min, was not dependent on the presence of sodium alginate. In contrast, the introduction of sodium alginate into conventional CPC, i.e. CPC without neutral phosphate in the liquid phase, resulted in no setting when the amount of sodium alginate introduced was more than 1 wt%. Powder X-ray diffraction analysis revealed no significant difference for the conversion of cement to apatite for any concentrations of sodium alginate studied (0-2.0 wt%). The mechanical strength of the cement increased rapidly with the addition of sodium alginate up to 0.8 wt% when the cement paste was immersed and kept in distilled water at 37 degrees C, whereas further addition of sodium alginate decreased the mechanical strength. The results obtained in this investigation, taken together with sodium alginate's known excellent biocompatibility and absorption behaviour, indicate that the use of sodium alginate composite FSCPC as nd-FSCPC should be of value in orthodontics and oral and maxillofacial surgery where the cement is exposed to blood.
In vivo setting behaviour of fast-setting calcium phosphate cement.
The in vivo setting behaviour of fast-setting calcium phosphate cement (FSCPC) between femoral muscles of the rat was investigated to evaluate the possible value of FSCPC for medical and dental application. Conventional CPC (c-CPC) and FSCPC were implanted between femoral muscles, and various aspects of the setting behaviour such as setting time, mechanical strength and conversion ratio of cement into hydroxyapatite (HAP: Ca10(PO4)6(OH)2) were measured by the Vicat needle method, diametral tensile strength (DTS) measurement, and quantitative powder X-ray diffraction (XRD) analysis, respectively. The setting time of FSCPC in vivo was 5-7 min, in contrast to 48 min for c-CPC. As a result of its fast setting, set specimens of FSCPC showed higher mechanical strength from the initial stage than c-CPC. Higher DTS values were observed in FSCPC than c-CPC implanted after 24 h. Powder XRD analysis revealed faster conversion of FSCPC than c-CPC into HAP, which was responsible both for the faster setting and higher mechanical strength from the initial stage. We concluded, therefore, that FSCPC may be used for a wide range of clinical applications, i.e. fields where fast setting is required such as orthopaedic, plastic and reconstructive, and oral and maxillofacial surgery.
Development of calcium phosphate based functional gradient bioceramics.
A functional gradient bioceramic that can function gradually with respect to body tissue was studied by changing the composition of calcium phosphate gradually from the surface to the inside. Diamond powder was spread on the surface of compact hydroxyapatite (HA) powder and fired at 1280 degrees C under reduced pressure, followed by firing under atmospheric conditions. The sintered body thus prepared was dense and alpha-tricalcium phosphate (alpha-TCP: alpha-Ca3(PO4)2) was found on its surface. The content of alpha-TCP gradually decreased with increasing depth from the surface. In contrast, the content of HA increased with increasing depth from the surface. The gradient ratio of alpha-TCP and HA depends on the firing time for each condition, i.e. reduced or atmospheric pressure. The alpha-TCP formation was ascribed to the decomposition of HA due to the spontaneous combustion of diamond powder.
Neuroendocrine carcinoma of the finger: a case report.
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Thigh augmentation.
Based on the experience with calf and buttock augmentation, a new type of implant was designed for thigh augmentation. A case report is presented.
A histological study of cutaneous thermal wounds using a Clostridium perfringens-derived wound healing substance with wound healing stimulation activity.
We studied the effects of a Clostridium perfringens-derived wound-healing substance (WHS) on the healing of thermal burn wounds. Third-degree burn injuries were inflicted on the back skin of rats. We histologically evaluated the effects of WHS ointments and compared them with those of lysozyme chloride ointment. We observed the formation of dermal collagen fibers and the increase of capillaries in the WHS ointment treated groups. From the results of hematoxylin and eosin staining and silver staining, an increase in capillaries was observed one week after the application of WHS ointment. Three weeks after the application, when the epithelization was in the final stage, capillary formation ceased. In the WHS ointment-applied groups, electron microscopic observation showed that new collagen fibers were regularly formed in the dermis. On the other hand, in the lysozyme chloride ointment-applied groups, new collagen fibers were present, but were irregularly formed. The main wound healing stimulative action of the WHS ointment could be due to its acceleration of new capillary formation.
[Treatment of progressive rectal cancer].
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Influence of crystallization on strength and color of castable glass-ceramics containing two crystals.
The mechanical properties, color and transparency of glass-ceramics are highly dependent on the ceramming temperature and/or amount of the crystal phase in the glass matrix. In this study, the influence of crystallization on the strength and color, translucency of castable ceramics containing crystalline apatite and magnesium titanate were measured. It was concluded that magnesium titanate precipitated during ceramming, appeared to be an important factor in decreasing total transmittance and in determination of the color of glass-ceramics.
Cold (0 degree C) ischaemic tolerance of latissimus dorsi free flaps in rats: a macroscopic and morphological study.
The purpose of this study was to define the cold (0 degree C) ischaemic tolerance (CIT) of the latissimus dorsi free flap in inbred rats. Flaps were isolated, stored at 0 degree C for periods of time ranging from 0 to 120 hr and then revascularised and reperfused for 14 days. Thereafter the CIT was assessed macroscopically, and by light microscopy. Electron microscopy was performed in flaps after 0 and 24 hr of reperfusion following a cold ischaemic interval ranging from 0 to 120 hr. From this preliminary study, it was concluded that the CIT was 48-72 hr.