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Biomedical subjects

M Kon

Publications and source records attributed to M Kon.

At least 19 recordsLinked to original sources
PubMed1998

Effects of added antibiotics on the basic properties of anti-washout-type fast-setting calcium phosphate cement.

The effect of added antibiotics on the basic properties of anti-washout-type fast-setting calcium phosphate cement (aw-FSCPC) was investigated in a preliminary evaluation of aw-FSCPC containing drugs. Flomoxef sodium was employed as the antibiotic and was incorporated into the powder-phase aw-FSCPC at up to 10%. The setting time, consistency, wet diametral tensile strength (DTS) value, and porosity were measured for aw-FSCPC containing various amounts of flomoxef sodium. X-ray diffraction (XRD) analysis was also conducted for the identification of products. To evaluate the drug-release profile, set aw-FSCPC was immersed in saline and the released flomoxef sodium was determined at regular intervals. The spread area of the cement paste as an index of consistency of the cement increased progressively with the addition of flomoxef sodium, and it doubled when the aw-FSCPC contained 8% flomoxef sodium. In contrast, the wet DTS value decreased with increase in flomoxef sodium content. Bulk density measurement and scanning electron microscopic observation revealed that the set mass was more porous with the amount of flomoxef sodium contained in the aw-FSCPC. The XRD analysis revealed that formation of hydroxyapatite (HAP) from aw-FSCPC was reduced even after 24 h, when the aw-FSCPC contained flomoxef sodium at > or = 6%. Therefore, the decrease of wet DTS value was thought to be partly the result of the increased porosity and inhibition of HAP formation in aw-FSCPC containing large amounts of flomoxef sodium. The flomoxef sodium release from aw-FSCPC showed the typical profile observed in a skeleton-type drug delivery system (DDS). The rate of drug release from aw-FSCPC can be controlled by changing the concentration of sodium alginate. Although flomoxef sodium addition has certain disadvantageous effects on the basic properties of aw-FSCPC, we conclude that aw-FSCPC is a good candidate for potential use as a DDS carrier that may be useful in surgical operations.

Biocompatible Materials↗
PubMed1998

Function of rat skeletal muscles after storage at 10 degrees C in various preservation solutions.

1. The purpose of this study was to assess the potential of various preservation solutions, orginally designed for solid organs, to protect muscle function during cold storage. 2. The soleus (SOL) and the cutaneous trunci (CT) muscle from the rat were isolated and stored for 2, 4 or 8 h at 10 degrees C. The solutions used, listed in order from an intracellular to an extracellular-like composition, were: University of Wisconsin (UW), Euro-Collins (EC), HTK-Bretschneider (HTK), reversed St. Thomas' Hospital (ST2) and Krebs-Henseleit (KH). After cold storage, the muscles were tested by direct electrical stimulation to obtain the maximum twitch tension (Pt) and the maximum tetanus tension (P0). Subsequently, the muscles were prepared for morphological analysis. 3. In general, storage at 10 degrees C caused a gradual decrease of Pt and P0 with time. After 8 h of storage in the extracellular-like solutions KH and ST2, the P0 was about 50% (SOL) and 35% (CT) of control. Eight hours of storage in intracellular-like solutions resulted in a P0 of 50% of control for HTK, in a P0 of 40% (SOL) and 67% (CT) for UW, but in a P0 of 5% (SOL) and 26% (CT) for EC. These findings corresponded well with the morphological observations. 4. It is concluded that the effects of 10 degrees C storage on skeletal muscle function are not predominantly determined by the intra- or extracellular-like composition of the solutions used. Both UW and HTK were most effective (P0 > 50% of control) in preserving muscle function.

Animals↗
PubMed1998

Electrically stimulated free-flap graciloplasty for urinary sphincter reconstruction: a new surgical procedure.

In electrically stimulated (dynamic) graciloplasty for urinary incontinence, the gracilis muscle is transposed into the pelvis, and the distal part is used to reconstruct a neosphincter. Clinical outcomes using this technique have been disappointing due to stricture of the urethra caused by ischemia in the distal part of the gracilis and limited gracilis length available for neosphincter construction. Furthermore, the urethra is twisted by the contracting gracilis, rather than circumferentially squeezed. The purpose of the present study was to test the anatomical and functional feasibility of a new surgical approach to reconstruct a urinary sphincter, using the gracilis muscle as a free flap. In 12 human cadavers, the anatomical feasibility for creating a neosphincter by using the gracilis free flap was determined. In all cases, transfer of the gracilis muscle into the pelvis as a free flap (with the nerve intact) was feasible, and ample muscle was available to construct a neosphincter around the bladder neck. Gracilis neosphincter function was studied in seven dogs. The left gracilis muscle was subjected to transfer into the pelvis as an innervated free flap to create a neosphincter around the urethra. The right (control) gracilis muscle was lifted as a single pedicle flap, remained in situ, and was wrapped around a stent to mimic the urethra. Function (expressed as peak pressure generation and fatigue rate) and surface perfusion were determined for all gracilis muscles. In each dog, both sides were compared using the paired Student's t test for statistical analysis, and no significant difference was measured for the two groups. In conclusion, an innervated gracilis free flap can be used to create a neosphincter around the bladder neck. In an acute study in dogs, function and perfusion of the innervated gracilis free flap are not compromised.

Animals↗
PubMed1998

The prepuce free flap: dissection feasibility study and clinical application of a super-thin new flap.

The aim of this study was to develop a free flap of the male prepuce. First, a dissection feasibility study was performed in eight male cadavers. Dissection proved feasible, and the mean surface area of the prepuce, when folded out, was 46.7 cm2. The mean pedicle length was 15 cm, with a mean diameter of the inferior external pudendal artery at its origin of 1.2 mm and a mean diameter of the inferior external pudendal vein at its origin of 1.9 mm. Next, a viability study was performed by isolating a prepuce free flap during male-to-female sex reassignment procedures. The flap as well as the residual skin of the penis shaft remained well perfused. Thereafter, the new prepuce free flap was successfully applied for the reconstruction of defects of the floor of the mouth, tongue, and oropharynx in two patients. The thinness and pliability of the flap, its large surface area, the long vascular pedicle, and the limited donor-site morbidity are the major advantages of this new flap. The possibility to raise the flap simultaneously with the tumor resection is an additional advantage. The small caliber of the flap artery seems to be the only drawback.

Aged↗
PubMed1998

Neurotmesis of the lateral femoral cutaneous nerve when coring for iliac crest bone grafts.

Two patients are presented suffering from meralgia paresthetica, owing to neurotmesis of the lateral femoral cutaneous nerve following bone-graft harvesting from the iliac crest with a cylindrical osteotome. Despite this donor-site complication, the advantages of a coring technique as compared with traditional bone-graft harvesting techniques are numerous: better cosmetic results, less pain, no need for general anesthesia, shorter hospitalization, and a minimum of donor-site morbidity. Also, this technique has proven itself easy and effective. To minimize donor-site morbidity, some clinical recommendations to avoid neurotmesis are given with regard to the anatomy and anatomic variations of the lateral femoral cutaneous nerve.

Adult↗
PubMed1998

Estimation of residual stress in dental porcelain by laser-Raman spectroscopy.

Residual stress in the surface of dental porcelain was estimated using laser Raman spectroscopy. Sixteen different magnitudes of residual stress were generated in commercial porcelain disks by tempering, ion exchange, and slow cooling. The specimens were analyzed using a laser-Raman spectrometer with an Ar+ laser. The Raman shift of the largest peak near 500 cm-1 originating from silica was used as an indicator of the level of residual stress. For comparison, the residual stress in the specimen was estimated by the indentation micro-fracture method. The Raman shift of the porcelain increased with increasing residual stress at 3.7 x 10(-2) cm-1/MPa (R2 = 0.89). The increase in the Raman shift corresponded to the increase in compressive stress. In addition, the value of full width at half maximum on the peak corresponded to the residual stress (-1.57 x 10(-1) cm-1/MPa: R2 = 0.82). These results revealed that the increase of residual stress in porcelain clearly appears on the Raman spectrum as an increase in the Raman shift. It is thus feasible to estimate residual stress in porcelain by laser-Raman spectroscopy.

Aluminum Silicates↗
PubMed1997

Tissue response to fast-setting calcium phosphate cement in bone.

Fast-setting calcium phosphate cement (FSCPC) is a promising new bioactive cement with a significantly short setting time (approximately 5-6 min) compared to conventional calcium phosphate cement (c-CPC) (30-60 min) at physiologic temperatures. As a result of its ability to set quickly, it is applicable in surgical procedures where fast setting is required. In this study, FSCPC was implanted in rat tibiae to evaluate tissue response and biocompatibility. FSCPC was converted to hydroxyapatite (HAP) in bone faster than c-CPC in the first 6 h. By 24 h, significant amounts of both FSCPC and c-CPC had been converted to HAP. The conversion of FSCPC into HAP further proceeded gradually, reaching 100% within 8 weeks. Infrared spectroscopic analysis disclosed the deposition of B-type carbonate apatite, which is a biological apatite contained in human dentin or bone, on the surface of the FSCPC. Histologically, FSCPC showed a tissue response similar to that of c-CPC. A slight inflammatory reaction was observed in the soft tissue apposed to both cements in the early period, and new bone was formed along the surface of the FSCPC at the adjacent bone. However, no resorption of either cement by osteoclasts or macrophages was observed within 8 weeks. We conclude that FSCPC is superior to c-CPC in clinical applications in oral and maxillofacial, orthopedic, plastic, and reconstructive surgery, since it shows a faster setting time and higher mechanical strength in the early period that are required in these surgical procedures, as well as osteoconductivity and excellent biocompatibility similar to that of c-CPC.

Animals↗
PubMed1997

Non-decay type fast-setting calcium phosphate cement: hydroxyapatite putty containing an increased amount of sodium alginate.

A hydroxyapatite [(HAP) Ca10(PO4)6(OH)2] putty that behaves like a putty or self-curing resin was made by increasing the amount of sodium alginate in non-decay type fast-setting calcium phosphate cement (nd-FSCPC). nd-FSCPC became viscous as the sodium alginate concentration was increased. The best handling properties were obtained when nd-FSCPC contained 8% sodium alginate in its liquid phase. When a 2-kg glass plate was placed on the paste, HAP putty spread to form an area three times that of FSCPC paste. Thus, HAP putty is expected to be easier to use than FSCPC in the filling of bone defects. HAP putty did not decay; in fact, it set within approximately 20 min when immersed in distilled water immediately after mixing. The wet diametral tensile strength value of HAP putty was approximately 12 MPa after 24 h, the same as that for nd-FSCPC containing 0.5% sodium alginate in its liquid phase, or FSCPC that is free from sodium alginate. The elements constituting set HAP putty were examined using powder X-ray diffraction and found to be predominantly apatitic minerals after 24 h. Since the handling properties of a putty or self-curing resin-like cement are very useful in certain surgical procedures, HAP putty made by increasing the sodium alginate concentration in nd-FSCPC is potentially a valuable new biomaterial for use in plastic and reconstructive surgery, as well as oral and maxillofacial surgery.

Alginates↗
PubMed1997

[Iatrogenic cicatricial endometriosis].

A woman aged 36, who two years previously had undergone a caesarean section, developed a painful swelling of the scar attributed to cicatricial endometriosis. This is a rare disorder brought about by peroperative displacement of normally or ectopically situated uterine mucous membrane to the surgical wound. There, it may proliferate and cause characteristic signs and symptoms that are simple to diagnose: cyclic pain, swellings and sometimes, bleedings. Pharmaceutical, possible hormonal treatment is of limited value, because cessation of the medication is frequently followed by recurrences. Consequently, ample surgical excision in endometriosis is to be preferred; this is to be regarded as a curative therapy.

Abdominal Muscles↗
PubMed1997

Surface modifications of titanium in calcium-ion-containing solutions.

The surface of titanium was modified in calcium-ion-containing solutions to improve bone conductivity. Three kinds of aqueous solutions for the modification were prepared using calcium nitrate, calcium chloride, and calcium oxide. The pH values of the solutions were 3.9, 7.4, and 12.6, respectively. At first, anatase powder was immersed in the solutions of 7 days to confirm the effect of the solutions on the modification. As a result, calcium titanate was formed on the anatase powder, indicating that the titanium surface was possibly modified by the solutions. Titanium plates were then immersed in the solutions at ambient temperature for 7 days, washed by deionized water, and dried. X-ray photo-electron spectroscopy of surface-modified titanium revealed that the surface-modified layer contained calcium hydroxide and/or calcium titanate. The surface-modified layer in which titanium was modified was thickest in this order: calcium oxide, calcium chloride, and calcium nitrate solutions. Apatite was formed on the surface-modified titanium in Hanks' solution while apatite was undetected on unmodified titanium. Therefore, the surface modification of titanium may improve bone conductivity. The amount of apatite corresponded to the thickness of the surface-modified layer and the amount of calcium in the layer.

Apatites↗
PubMed1997

Review of facilitated approaches to vascular anastomosis surgery.

BACKGROUND: There is an increasing demand for an easier, quicker, less damaging, but reliable procedure to create a vascular anastomosis. This demand is not new but is revitalized by the movement of vascular procedures in various specialties, including cardiac surgery, toward minimally invasive procedures. This article reviews the most important representatives of devices or methods that have been developed in the last two centuries. METHODS: A thorough literature search was performed. The outcome is presented and discussed in four parts: (1) stapling and clipping devices, (2) coupling devices, (3) glues, and (4) laser welding. RESULTS: Stapling devices have not become the standard fashion to create an anastomosis because they are too complicated to use. In selected cases clips have potential in vascular surgery. There is a ring-pin coupling system available that is easy to use and especially suitable for creating an end-to-end anastomosis. The ideal glue is yet to be developed, and the currently available laser welding techniques have to become refined. CONCLUSIONS: It is anticipated that the future lies in hybrid techniques that combine sutures or clips with glues or laser-welding techniques.

Anastomosis, Surgical↗
PubMed1997

The role of suture material in hypertrophic scar formation: Monocryl vs. Vicryl-rapide.

The development of hypertrophic scars and keloids is an unsolved problem in the process of wound healing. There are indications that inflammation plays an important role in this process, but its exact mechanism remains unclear. In this study the amount of inflammation and the development of hypertrophic scars and keloids was investigated in inframammary skin incisions sutured with synthetic absorbable suture materials: a monofilamentous suture (Monocryl) compared with a multifilamentous suture (Vicryl-rapide). In 81 breast reduction patients Monocryl (N = 28) has proved to give significantly smaller, less reactive scars with a lower tendency toward hypertrophic scar formation compared with Vicryl-rapide (N = 53).

Abscess↗
PubMed1997

Influence of modification of Na2O in a glass matrix on the strength of leucite-containing porcelains.

The desirable thermal properties of matrix glass to the strength of feldspar porcelain with leucite crystal were investigated. Five kinds of feldspar glasses, each with different a content of Na2O, were prepared for the matrix glasses of the leucite-containing porcelains. The specimens were arranged by mixing each glass powder with high-purity natural leucite crystals (0, 20 and 40%) followed by firing. The thermal properties of the glass and the transformation temperature of the leucite were measured. A three-point bending test was performed to measure the flexural strength of the porcelains. The glass transition temperature and deformation temperature of the glass-only porcelains were decreased as the Na2O content increased. The Na2O-modified glasses were substantially strengthened by the leucite dispersion. However, the strength of the porcelains was affected by the relation between the transformation temperature of the leucite and the thermal properties of the glass matrix. It was concluded that control of the residual stress in the composite porcelain is an important factor in developing high strength porcelain containing leucite.

Aluminum Silicates↗
PubMed1997

Adventitial stripping does not strip the adventitia.

This study investigates the process of stripping the adventitia off a blood vessel, which is a normal procedure prior to performing a microvascular anastomosis. In five rats, the common carotid and the superficial femoral arteries of one side were stripped sharply, whereas the arteries of the other side were left unstripped to serve as controls. In a further set of five rats, the arteries were stripped bluntly. Immediately following stripping, experimental and control arterial segments were removed. Histology of cross sections of the segments was studied. In no case was there complete removal of the adventitia. When stripped and control arterial sections were compared, no significant difference between cross-sectional adventitial areas could be demonstrated. Morphologic study revealed that stripping mainly removes large collagen fibers from the adventitia. The small collagen fibrils that are still in place fan out in such a way that although considerable tissue is removed, the volume that the adventitia occupies remains the same. Stripping the adventitia does not cause complete removal of the adventitia, and in this study no significant reduction in the adventitial volume could be found. Stripping does, however, allow a better view of the cut edge of the vessel wall under an operating microscope. Since blunt stripping could cause damage to other vessel wall layers, sharp stripping is to be preferred.

Anastomosis, Surgical↗
PubMed1996

Anatomy of the feeding blood vessels of the cremaster muscle in the rat.

Since the early seventies over 300 studies have used the cremaster muscle as a flap model, yet little has been reported on the upstream feeding vessels of this muscle. The purpose of this study was to investigate the anatomy of the cranial feeding vessels of the left and right cremaster muscle in Sprague-Dawley rats. An additional aim was to compare these results with the anatomy of the feeding vessels of the cremaster muscle in another strain (Wistar). To permit identification of the cranial feeding vessels, the pedicle was dissected very carefully and thereafter perfused with green dye, which was administered through a cannula placed in the distal femoral artery. In Sprague-Dawley rats it was found that the cremaster muscle in only 30% of the animals received its total blood supply through the superior external pudendal artery. In Wistar rats the same was true in less than 45%. The cremaster muscle of the rest of the animals appeared to receive its blood either in part or in total from the hypogastric trunk. We suggest that the name pudic-epigastric trunk be abandoned.

Animals↗