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Biomedical subjects

S Jovanovic

Publications and source records attributed to S Jovanovic.

At least 55 records · Page 3Linked to original sources
PubMed1998

Acquired resistance of a mammalian cell line to hypoxia-reoxygenation through cotransfection of Kir6.2 and SUR1 clones.

Reoxygenation after transient hypoxia is a common clinical condition that often causes greater tissue damage than persistent hypoxia itself. This warrants the development of a means to protect cells against hypoxia-reoxygenation injury. Adenosine triphosphate (ATP)-sensitive K+ (KATP) channels have been proposed to play an essential role in the mechanisms of endogenous cellular protection. Thus far, however, KATP channel proteins have not been exploited to generate an injury-resistant cellular phenotype by delivering KATP channel genes into injury-prone cells. A first step in this direction is the evaluation of the outcome of transferring genes encoding KATP channels into a KATP channel-deficient cell type exposed to metabolic stress. Untransfected COS-7 monkey kidney cells, which natively lack KATP channels, were found to be vulnerable to hypoxia-reoxygenation injury, which induced cytosolic Ca2+ loading, as measured by digital epifluorescent imaging. COS-7 cells cotransfected with KATP channel genes, Kir6.2 and SUR1, gained resistance to hypoxia-reoxygenation. This acquired resistance was abolished by glyburide, the KATP channel antagonist. We have previously shown that Kir6.2 and SUR1 physically associate to form a functional KATP channel, not reconstituted by either of the subunits alone. Transfection with individual channel subunits, Kir6.2 or SUR1, failed to produce resistance to hypoxia-reoxygenation induced Ca2+ loading. This is a first demonstration that transfer of KATP channel subunits can generate an injury-resistant cellular phenotype. The findings from this study may, thus, provide a framework for future therapeutic strategies based on gene delivery of KATP channel subunits in cells and tissues vulnerable to hypoxia-reoxygenation insults.

Animals↗
PubMed1997

Effects of pulsed laser systems on stapes footplate.

BACKGROUND AND OBJECTIVE: The aim of the present study was to investigate the tissue ablation capacity of various pulsed lasers at the stapes footplate. STUDY DESIGN/MATERIALS AND METHODS: Isolated human stapes and bovine compact-bone platelets were used to determine the effective laser parameters and appropriate application technique for achieving a perforation measuring 500-600 microns in diameter. Of interest were also the shape and quality of the perforations, the reproducibility of the perforation effect, and the thermically altered marginal zones occurring at the footplate. Three pulsed laser systems were used: excimer, holmium:YAG (Ho:YAG), and erbium:YSGG (Er:YSGG) lasers. RESULTS: The tissue-ablating effect of pulsed laser systems permits a precise and controlled management of the stapes footplate through low and readily reproducible ablation rates. The extent of thermic side effects at the footplate is lower in comparison to the purely thermically acting cw and superpulse laser systems. The Er:YSGG laser exhibits the highest ablation rate at the stapes and is thus the most effective laser for perforation of the stapes footplate. Though somewhat less effective, the Ho:YAG laser also appears to be suitable for stapedotomy. On the other hand, we do not consider the applied excimer laser (308 nm) to be particularly appropriate at the stapes because of its low ablation rates. CONCLUSION: Thus, the erbium laser could represent an alternative to the argon, KTP 532, and CO2 lasers, already clinically successful in stapes surgery. However, further studies are necessary to examine the transmission of thermic energy into the vestibule and the acoustic stress to the inner ear during laser stapedotomy, to be able to make a definitive statement about the safest and most effective laser system for stapes surgery.

Animals↗
PubMed1997

[New treatment possibilities for skin changes with the CO2 laser in head and neck surgery].

Laser treatment of various skin changes has become common clinical practice in recent years. Due to its physical properties, the CO2 laser is particularly well suited for cutting and ablating tissue. The high absorption of its wavelength in water (lambda = 10600 nm) is responsible for its low penetration depth in biological tissue. Shortening the exposure time minimizes thermal side effects, such as carbonization and coagulation. This effect can be lessened with the Silk Touch scanner, since the focussed laser beam is moved over a defined area by rapidly rotating mirrors. This enables a controlled and reliable removal of various dermal lesions. Particularly well-suited for treatment hypertrophic scars, post-acne scarring, perioral and periorbital wrinkles, rhinophymas and benign neoplasms including verruca vulgaris. Cosmetically favorable reepithelialization of the treated skin surfaces occurs within a very short time after treatment. Periorbital resurfacing and correction of a rhinophyma are used as examples of dermal treatment with the CO2 laser and the Silk Touch scanner.

Adult↗
PubMed1997

Rehabilitation in Franceschetti syndrome: an interdisciplinary approach using bone-anchored hearing aids.

The purpose of the study was to determine the effectiveness of a concept of combined interdisciplinary rehabilitation for children with mandibulofacial dysostosis, developed at the Center for Facial Malformations. It consists of binaural implantation of bone-anchored hearing aids and gradual distraction of the mandible. After audiological testing and mandibular distraction on a phantom head designed with data from a spiral CT, the surgery was done in three steps: implanting the fixtures for BAHA and the bone-lengthening device, removing the device after six weeks and completing the BAHA implantation two months later. The distraction procedure and orthodontic treatment were performed on an outpatient basis. The results (six patients, ages 6-19 years) were excellent: after implantation of the BAHA system speech perception increased from approximately 85% with the conventional BCHA to 95-100% with the BAHA. Quality of life was reported to be much better because of the general cosmetic improvement as well as the good acoustic orientation and sound quality with the new hearing devices. We conclude that the interdisciplinary approach provides favorable conditions for rehabilitation in cases of complex malformations of the head and neck.

Abnormalities, Multiple↗
PubMed1997

[Poisoning of a family by a mercury-containing ointment].

Within the framework of a project entitled "Observation by Public Health Offices" we discovered a strikingly high mercury concentration of 30 micrograms in the urine of a 10-year old girl from an Albanian family formerly residing in the Kosovo area in Serbia. We investigated into the cause of this mercury load and found that it was also present in other members of the same family. Symptoms of mercury poisoning were evident to varying degrees in individual family members. Ultimately, we traced the source to a bleaching ointment containing mercury. On analysing the same we found a mercury content of 389 mg per g ointment. The use of this ointment with its extremely high mercury content had also contaminated the living-rooms.

Adolescent↗
PubMed1996

Effects of continuous-wave laser systems on stapes footplate.

BACKGROUND AND OBJECTIVE: The aim of the present study was to clarify which of the presently available continuous-wave laser systems are best suited for application in stapes surgery. STUDY DESIGN/MATERIALS AND METHODS: Isolated human stapes and bovine compact-bone platelets were used to investigate the connections between the parameters of various laser systems and their effects on bone tissue. The purpose was to optimize the laser parameters required to achieve a perforation measuring 500 microns to 600 microns in diameter. Three different laser systems were applied: the argon and CO2 laser in continuous wave (cw) mode and the CO2 laser in superpulse mode. RESULTS: The suitability of the argon laser for stapedotomy is doubtful in view of the lower absorption coefficient of the stapes for the argon beam and the considerable influence which the degree of pigmentation of the irradiated medium exerts on its effect with the resultant poor reproducibility of the perforation diameter. The beam of the CO2 laser is far better absorbed at the footplate than that of the argon laser. This results in higher effectivity, lower thermic side effects, and better reproducibility of the perforation. The two modes of the CO2 laser do not show any appreciable differences. CONCLUSION: The experimental results presented indicate that the CO2 laser in cw and superpulse mode is the most suitable of the systems now clinically applied in stapes surgery.

Animals↗
PubMed1996

[Intra-orbital space occupying lesion. Differential diagnostic considerations based on a rare case].

The differential diagnosis of an intraorbital tumor is discussed on the basis of a rare case of cyst formation that presented clinically in the lacrimal duct. Rapid progression of exophthalmos and visual loss required an immediate surgical intervention. Using a medial orbitotomy, a cystic tumor was extirpated that had no connection to the paranasal sinuses. Postoperatively, the visual defect and exophthalmos resolved completely. This case demonstrates the problems of differential diagnosis within the orbit that require close interdisciplinary cooperation. The final diagnosis can often be made only after surgical exploration and histopathology of tissue specimens.

Aged↗
PubMed1996

Does laser turbinectomy influence local allergic inflammation in the nose?

The purpose of our study was to evaluate the effects of laser turbinectomy on local allergic inflammation by measuring the secretion of mediators (histamine, bradykinin, and TAME-esterase activity) in nasal lavage fluid after nasal provocation with different allergen concentrations. Our study included 15 patients, aged 15-35 years, who displayed perennial housedust-mite rhinitis (positive prick test, RAST class > 2, and positive nasal provocation with Dermatophagoides pteronyssinus (D.p.) extract) and hypertrophic inferior turbinates. Rhinomanometry (Rhino-test 441, Allergopharma, Germany) and nasal provocation with D.p. extract (Allergopharma, Germany) followed by lavage were performed in all patients. The procedure was repeated three and 12 months after Neodynium:YAG laser turbinectomy. Three and 12 months after laser turbinectomy, we found a significant improvement of nasal flow (p < 0.01 and p < 0.05, respectively) and resistance (p < 0.1 and p < 0.01, respectively) with a tendency towards airway blockage in the long-term follow-up, but no changes in mediator levels of nasal lavages after allergen provocation, suggesting that laser turbinectomy has no effects on local allergic inflammation.

Adolescent↗
PubMed1996

[Thermal stress on the inner ear in laser stapedotomy].

Apart from ablation properties at the stapes footplate, the degree of thermal stress of the inner ear is important when considering the suitability of pulsed lasers for stapedotomy. The aim of the present study was to compare the heating of cochlear structures with presently available pulsed laser systems during stapedotomy under reproducible conditions. Temperature increases and heat-exchange processes were examined in a physiologic model of the cochlea using various laser parameters effective for footplate perforations. With all systems, increases in energy density, number of pulses and resultant total energy led to higher temperatures. In the effective energy density range, the highest temperature increases achieved with the requisite number of pulses at a distance of 2 mm behind the footplate perforation were 30 degrees and 26 degrees C with the pulsed CO2 and Ho:YAG lasers, respectively. The lowest temperature recorded was 5.5 degrees C with the Er:YAG and <5 degrees C with the Er:YSGG laser. The excimer laser investigated at only one energy density showed maximum temperatures of 10 degrees C. With regard to possible inner ear damage from thermal stress during laser stapedotomy, the Er:YSGG laser can be used safely over a relatively broad energy density range. The Er:YAG laser investigated also appears suitable for stapedotomy when considering thermal effects. In contrast, application of the pulsed CO2 laser at parameters effective for stapedotomy leads to high temperatures and wide scattering to compromise its use. The Ho:YAG laser also appears to be unsuitable because of the higher energy density and pulse rate required for sufficient perforation and the resultant higher temperature increases in the perilymph. Although footplate perforations can be achieved with only slight temperature increases in the fluid of the cochlea model, the excimer laser does not seem to be appropriate for stapedotomy because of the long period of heat exposure required and the lower ablation rates at the stapes.

Body Temperature↗
PubMed1995

Experimental studies on the suitability of the erbium laser for stapedotomy in an animal model.

Animal experiments in mature guinea pigs were devised to determine whether and to what extent inner ear damage can be caused by in vivo use of the erbium laser for stapedotomy. The present study examined the laser effect in connection with perforation of the basal convolution of the cochlea and subsequent application in the opened cochlea. Acoustic evoked potentials as compound action potentials (CAP) were recorded for changes in inner ear function. Findings demonstrated that five applications of the erbium:YSGG (yttrium-scandium-gallium-garnet) laser (energy, 85 mJ/pulse; energy density, 36 J/cm2) were needed to create a footplate perforation of 500-600 microns and did not lead to CAP alteration in any animal (n = 20). An increase of the repetition rate from 1 to 5 Hz likewise caused no CAP alteration (n = 17). Application of high total energies in the open cochlea (n = 5) to determine the safety of the laser system for stapedotomy revealed that a 10-fold increase in the total energy required for adequate perforation led to irreversible CAP alterations and no CAP could be recorded at a 15-fold increase in total energy. In contrast, a 5-fold maximum increase in total energy caused no CAP alterations. These results demonstrate the safety of the Er:YSGG laser comparable to that of the CO2 laser for stapedotomy, supporting its utility as an alternative method for surgery.

Acoustic Stimulation↗
PubMed1995

External fixation as a primary and definitive treatment of open limb fractures.

This paper analyses the medical records of 5024 injured persons treated and operated on at the Surgical Clinic of the Clinical Hospital in Osijek, during the war against Croatia (1991 and 1992). There were 1653 (33.0 per cent) admitted, while the rest were treated as out-patients. Of the admitted patients 82.7 per cent (1372) had limb injuries. In 760 (15.0 per cent) of the wounded, 1320 limb fractures caused by explosives were diagnosed, out of which 856 were of the lower and 464 of the upper limbs. One hundred and ninety-two (3.9 per cent) were treated by external fixation. External fixators were applied to 147 lower and 68 upper open long bones, respectively. Adequate reconstructive operations were performed on 106 (2.1 per cent) patients with associated injuries to important blood vessels. The stabilization of the open and unstable external fractures was achieved by external fixation, mostly at one level, regardless of the wound size. The importance of good wound cleaning has been particularly stressed as well as bone fragment reposition. Special attention has been given to the preoperative and intra-operative assessment of the limbs. In 20 patients (9.3 per cent) treated with external fixation, osteitis occurred. Twenty-one more patients (9.7 per cent), because of bad fracture healing after external fixation, were submitted to secondary internal bone fixation combined with bone grafts. Out of these, nine (42.8 per cent) developed osteitis as a consequence of the additional treatment.

Arm Injuries↗
PubMed1995

[Animal experiment studies on CO2 laser stapedotomy].

Experiments were performed in guinea pigs to clarify which, if any, of the CO2 lasers used can damage the inner ear on application of the laser parameters required for stapedotomy. A further aim was to determine their application safety. The basal convolution of the guinea-pig cochlea was chosen as the application site, since its thickness is similar to that of the human stapes base. We examined the laser effect in connection with perforation of the basal convolution and subsequent application in the open cochlea. Acoustic evoked potentials (compound action potentials [CAP]) yielded information on inner-ear function. Animals without laser treatment were used as controls. Perforation of the basal convolution and laser applications in the open cochlea with the same parameters did not lead to a measurable CAP alteration with the CO2 cw laser (power: 8 W, pulse duration: 50 ms, power density: 3200 W/cm2). An increase of the laser power to 15 W (power density: 6000 W/cm2) and of the pulse duration to 200 and 500 ms (energy: 3 J and 7.5 J) caused partly irreversible CAP alterations; finally, no potential could be recorded any more at a maximal laser power and pulse duration (15 W and 500 ms). Examination of high power densities (40,000 and 60,000 W/cm2) through reduction of the laser beam diameter to 180 microns yielded comparable results.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

[Nd:YAG laser surgery in treatment of allergic rhinitis].

The purpose of our study was to evaluate the effects of laser turbinectomy on local allergic inflammation by measuring the secretion of mediators (histamine, bradykinin, and TAME-esterase activity) in nasal lavage fluid after nasal provocation with different allergen concentrations. Our study included fifteen patients, aged fifteen to 35, who displayed perennial house-dust-mite rhinitis (positive prick test, RAST class > 2 and positive nasal provocation with Dermatophagoides pteronyssinus [D.p.] extract) and hypertrophic inferior turbinates. Rhinomanometry (Rhino-Test 441, Allergopharma, Reinbeck, Germany) and nasal provocation with D.p. extract (Allergopharma, Germany) followed by lavage were performed in all patients. The procedure was repeated three and twelve months after neodymium:YAG laser turbinectomy. Three and twelve months after laser turbinectomy, we found a significant improvement of nasal flow (p < 0.01, p < 0.05) and resistance (p < 0.01, p < 0.01) but no change of mediator levels in nasal lavage after allergen provocation, suggesting that laser turbinectomy has no effects on local allergic inflammation.

Adolescent↗
PubMed1995

[Subjective and objective evaluation of the outcome of rhinoplasty. A retrospective study].

Between 1983 and 1988, 206 patients underwent a septorhinoplasty in the ENT Department of the University Hospital Benjamin Franklin in Berlin. The results of the operation were analysed by an "objective" evaluation form including measurements of cephalometric angles and a "subjective" questionnaire reflecting the patient's view. Ninety-nine patients responded to our questionnaire. About one third of our patients were foreigners (mostly Turks). Seventy-five percent of the results were good in objective as well as subjective terms. Comparison of results between the two sexes did not show a significant difference. A relevant discrepancy between the objective and the subjective results was seen in the foreign patients. The low average age and therefore unrealistically high expectations are a possible explanation for this phenomenon. Patients with small preoperative deformities also turned out to be less satisfied with the outcome even though the objective result was better. While obtaining the objective results, we also realized that the nasofrontal angle seems to be of minor importance for the facial profile. The nasofacial and the nasolabial angle actually seem to be more important for the rhinoplasty and reflect the aesthetic correction of the nose better than the nasofrontal angle. It was much more often possible to correct the nasofacial and the nasolabial angle, while the nasofrontal angle remained uncorrected in many cases. Our retrospective study was able to answer the question whether the aesthetic outcome after rhinoplasty can be rated objectively.

Adult↗
PubMed1995

[Revision of the stapes foot plate with various laser systems. 1: Continuous laser irradiation].

During stapedotomy, the small dimensions and highly sensitive anatomic structures present require the highest degree of precision and safety. The risk of damage to middle and inner ear structures through manipulation with conventional instruments can be reduced by non-contact perforation of the footplate with the laser beam. The present study was devised to clarify which of the presently available laser systems was best suited for use in stapes surgery and thus represent a significant alternative to conventional stapedotomy. Isolated human stapes and bovine compact-bone platelets were used to investigate the connections between the parameters of various laser systems and their effects on bone tissue. The aim was to optimize the laser parameters required to achieve a perforation of 500 microns to 600 microns in diameter. In addition, the thermal effects of laser irradiation were assessed. Three different systems were employed: the argon and CO2 lasers in continuous wave (cw) modes and the CO2 laser in superpulse mode. The lasers investigated offered the advantage of achieving an adequately large perforation with one or a few juxtaposed applications but caused in part extensive thermal side effects at the stapes footplate. To reduce thermal effects, footplate perforation was best performed by several juxtaposed single shots at low power, short pulse duration and small beam diameter. The suitability of the argon laser for stapedotomy was rendered doubtful in view of the lower absorption coefficient of the stapes for the argon laser beam and the considerable influence exerted by the degree of pigmentation of the irradiated tissue sites with a resultant poor reproducibility of the perforation diameter.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

[Modifying the stapes footplate with various laser systems. II. The pulsed laser].

The object of the present study was to examine the tissue ablation capacity of various pulsed lasers at the stapes footplate. Isolated human stapes and bovine compact-bone platelets (thickness 90 microns) were used to determine effective laser parameters for achieving a perforation measuring 500 microns to 600 microns in diameter. Apart from achieving the perforation diameters, particular attention was given to the form and quality of the perforations, reproducibility of the perforation effect and the thermally altered border zones occurring at the footplate. Four pulsed laser systems were used: excimer, Ho:YAG, Er:YSGG and CO2 lasers. An adequately large perforation generally could only be achieved by several repeated shots at the same application site, since only a small amount of tissue was ablated per application. The mechanism of the photoablation caused the extent of the thermal side effects to be markedly lower than with the continuous wave (cw) and superpulse systems. For this reason and because of their highly reproducible perforation effect, they were basically better suited for stapedotomy than the cw systems. It was possible, however, that as a result of the longer application time and the need to repeatedly irradiate the same application site, the higher pulse counts could prove to be disadvantageous in clinical practice. Among the pulsed laser systems, the Er:YSGG laser had the highest ablation rate at the stapes and was thus the most effective laser for interventions at the footplate. Although somewhat less effective than the Er:YSGG laser in our studies, the Ho:YAG and pulsed CO2 lasers also appear to be suitable for stapes surgery. On the other hand, we did not consider the excimer laser (308 nm) to be particularly effective at the footplate because of its low ablation rates.

Animals↗