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Biomedical subjects

G Mast

Publications and source records attributed to G Mast.

At least 19 recordsLinked to original sources
PubMed2000

[Pedicled musculocutaneous and fasciocutaneous flap].

Pedicled musculocutaneous and fasciocutaneous flaps are still a prerequisite of reconstructive surgery. Although microvascular free flap transfer today plays a major role in modern one-step reconstruction concepts, the surgeon should be familiar with the anatomy and techniques of pedicled flaps. In the head and neck region especially, pedicled flaps from the pectoralis major and the latissimus dorsi muscle are of clinical importance. A major advantage of these flaps is in their simple and standardized surgical technique, which requires no further surgical qualification compared to microvascular transfer. The flaps are reliable and safe. They have a high degree of resistance against infection and therefore can be used in compromised tissues, which are frequently found in irradiated patients. The disadvantages are a reduced mobility regarding the arch of rotation. Pedicled fasciocutaneous flaps have no importance in reconstructive surgery of the head and neck region.

Follow-Up Studies↗
PubMed1998

[3-D imaging of the facial surface by topometry using projected white light strips].

Three-dimensional registration of the facial surface by methods which are currently in use is difficult because of the long measuring times required by point-based imaging systems. Artifacts caused by movement appear, e.g., blinking. Also the production of a facial plaster-cast model for measuring is not an adequate solution. In order to acquire data of the facial surface in a contact-free manner, a system is needed that has short measuring times, is able to record data of complex surfaces and at the same time does no harm to the open eyes. The method described here represents a new development of an industrial high tech CAD/CAM system. Unlike customary point-based imaging systems, the stripe projection method works using entire planes. Structured light is aimed at the surface to be measured, recorded by videocamera and calculated by triangulation; then the different views are combined by computer. The system has an optic sensor that can record approximately 500,000 measuring points within seconds (ca. 1.7s). Test persons' faces and plaster-cast models of them (n = 15) were measured comparatively and serially (n = 5) to test the validity and reliability of the method for maxillofacial procedures. These investigations show that this method is appropriate for recording three-dimensional soft-tissue profiles. First studies on patients before and after dysgnathia operations were undertaken. A prospective long-term study for collecting data on pre- and postoperative dysgnathia patients has been begun. Initially, it will record the changes in facial soft tissue on the basis of skeletal displacement. Later, predictions about the soft-tissue changes subsequent to dysgnathia surgery can be worked out on the basis of stored data matched with three-dimensional bone data.

Adolescent↗
PubMed1998

[Anuria].

Explore the source record for details and available documents.

Adult↗
PubMed1996

Continued benefit of coronary stenting versus balloon angioplasty: one-year clinical follow-up of Benestent trial. Benestent Study Group.

OBJECTIVES: This study sought to determine the 1-year clinical follow-up of patients included in the Benestent trial. BACKGROUND: The Benestent trial is a randomized study comparing elective Palmaz-Schatz stent implantation with balloon angioplasty in patients with stable angina and a de novo coronary artery lesion. Seven-month follow-up data have shown a decreased rate of restenosis and fewer clinical events in the stent group. It is not established whether this favorable clinical outcome is maintained for longer periods or whether coronary stenting defers restenosis and its subsequent clinical manifestations. METHODS: To clarify this uncertainty, we updated clinical information on all but 1 of 516 patients enrolled in the Benestent trial (257 in balloon group, 259 in stent group) at least 12 months after the intervention. Major clinical events (primary clinical end point) were tabulated according to the intention to treat principle and included death, the occurrence of a cerebrovascular accident, myocardial infarction, the need for bypass surgery or a further percutaneous intervention in the previously treated lesion. RESULTS: After 1 year, no significant differences in mortality (1.2% vs. 0.8%), stroke (0.0% vs. 0.8%), myocardial infarction (5.0% vs. 4.2%) or coronary bypass graft surgery (6.9% vs. 5.1%) were found between the stent and balloon angioplasty groups, respectively. However, the requirement for a repeat angioplasty procedure was significantly lower in the stent group (10%) than the balloon angioplasty group (21%, relative risk [RR] 0.49, 95% confidence interval [CI] 0.31 to 0.75, p = 0.001), and overall primary end points were less frequently reached by stent group patients (23.2%) than those in the balloon group (31.5%, RR 0.74, 95% CI 0.55 to 0.98, p = 0.04). No differences were found between groups with respect to functional class angina and prescribed medication at the time of follow-up. CONCLUSIONS: These clinical follow-up data show that the benefit of elective native coronary artery stenting in patients with stable angina is maintained to at least 1 year after the procedure and results in a significantly reduced requirement for repeat intervention.

Angina Pectoris↗
PubMed1996

[Treatment of mandibular fractures with different fixation techniques--results of a prospective fracture study].

In a prospective study 150 adult patients with mandible fractures were analysed. Criteria for entry into the study were fractures of the mandibular body with and without associated condylar fractures. The fractures must fit to the Spiessl-classes F1 and F2, L1 to L4, W0 to W3 and the patients must have had a sufficient dentition to judge their occlusion. Not included were patients with combinations of mandible and Le Fort fractures, comminuted and defect fractures and patients who could not communicate preoperatively in order to have a full preoperative examination. The patients were equally distributed among 3 different treatment groups. Group 1 was treated conservatively with MMF, only displaced fractures which needed open reduction were internally fixed with wire osteosynthesis. Group 2 received rigid internal fixation with AO 2.7-plates from an intraoral approach, group 3 internal fixation with miniadaption-plates also from an intraoral approach. Using a standardized treatment protocol the patients were followed in defined intervals up to a maximum of 2 years after therapy. Group 1 presented with the lowest complication rate, group 2 with the highest rate of overall complications as far as disturbances of the occlusion and sensory disturbances were concerned. Except one plate fracture in group 3 with subsequent pseudarthrosis, which required a reosteosynthesis with a rigid plate, no major complications in bone healing were observed.

Adult↗
PubMed1996

[Development of a mandibular model for evaluating and optimizing the design of osteosynthesis materials using finite element analysis].

The present study was designed to investigate biomechanical and clinical changes in the mandibular complex by means of finite element analysis. An analytical model developed from human native mandibles was used for this model, CT image data were transferred to a computer, and an edge extraction program generated the cross-section of bone by specifying a range of CT values for each slice. Pixel data from the CT scan were converted into a vector of points (x, y, z) which can specify the boundaries of bone. Lateral surfaces are defined by stacking up the slices and making use of the vectorized data. The constructed model was used as input data for the finite element analysis. The models were solved for stresses and forces. The highest principal stresses occurred at the bite point, anterior aspects of the coronoid processes, symphyseal region, and right and left sides of the mandibular corpus. For further investigation muscular structures have to be integrated to establish a model, which can be analysed under multivariate aspects.

Biomechanical Phenomena↗
PubMed1993

Usefulness of quantitative and qualitative angiographic lesion morphology, and clinical characteristics in predicting major adverse cardiac events during and after native coronary balloon angioplasty. CARPORT and MERCATOR Study Groups.

Major, adverse cardiac events (death, myocardial infarction, bypass surgery and reintervention) occur in 4 to 7% of all patients undergoing coronary balloon angioplasty. Prospectively collected clinical data, and angiographic quantitative and qualitative lesion morphologic assessment and procedural factors were examined to determine whether the occurrence of these events could be predicted. Of 1,442 patients undergoing balloon angioplasty for native primary coronary disease in 2 European multicenter trials, 69 had major, adverse cardiac procedural or in-hospital complications after > or = 1 balloon inflation and were randomly matched with patients who completed an uncomplicated in-hospital course after successful angioplasty. No quantitative angiographic variable was associated with major adverse cardiac events in univariate and multivariate analyses. Univariate analysis showed that major adverse cardiac events were associated with the following preprocedural variables: (1) unstable angina (odds ratio [OR] 3.11; p < 0.0001), (2) type C lesion (OR 2.53; p < 0.004), (3) lesion location at a bend > 45 degrees (OR 2.34; p < 0.004), and (4) stenosis located in the middle segment of the artery dilated (OR 1.88; p < 0.03); and with the following postprocedural variable: angiographically visible dissection (OR 5.39; p < 0.0001). Multivariate logistic analysis was performed to identify variables independently correlated with the occurrence of major adverse cardiac events. The preprocedural multivariate model entered unstable angina (OR 3.77; p < 0.0003), lesions located at a bend > 45 degrees (OR 2.87; p < 0.0005), and stenosis located in the middle portion of the artery dilated (OR 1.95; p < 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1991

Organ-preserving surgery in renal cell carcinoma--change of the therapeutical concept.

From 1976 to 1989 in 90 patients (n = 98 tumors) with renal cell carcinoma organ-preserving surgery was performed (age 25-84 years, mean 58 years). Imperative indications for organ preservation (tumor removal by partial resection with or without clamping of the artery, autotransplantation) (n = 18) were chronic renal failure, benign pathology of contralateral kidney, functional or anatomical solitary kidney, and bilateral tumors. Elective organ-preserving surgery (n = 72) was done for small peripherally located lesions and in cases of uncertain preoperative tumor dignity. Tumors removed for imperative indications were 2-11 cm (mean 6.5 cm) in size. In the elective group tumor size ranged from 1 to 6 cm (mean 3.5 cm). Follow-up was 3 months to 13 years, 1 postoperative mortality was observed in the group with imperative indication. 15/90 patients are alive without tumor, 1 patient with metastasis, 1 patient died because of metastasis and 1 for unrelated reasons. All patients beside 1 in the group with elective indication are alive without metastasis. Renal cell carcinoma has changed its clinical feature. More and more tumors are detected by ultrasound without clinical symptoms. Though radical tumor nephrectomy still is the standard operation for renal cell cancer, in cases especially with small tumors the indication for organ-preserving operation with regard to these excellent results should be given more often.

Carcinoma, Renal Cell↗
PubMed1991

[Ameloblastomas in the growth period--aspects of differential diagnosis and therapy].

This paper is focussed on problems associated with the histological evaluation of odontogenic tissues in the growth period. It is particularly parts of the dental lamina or harmless odontogenic tumors (e.g. ameloblastic fibromas) that can be mistaken for ameloblastomas. Since these false diagnoses may occur in growing patients, radical resections for treatment of ameloblastomas should only be performed after a second histological evaluation and when typical intraosseous lesions are present.

Adolescent↗
PubMed1990

[Developmental disorders of the permanent dentition following fractures of the visceral cranium during the growth period. Incidence and morphological findings].

The retrospective examination of 70 patients who had suffered fractures in tooth-bearing segments of the maxilla and the mandible when they were between one and twelve years old revealed a high incidence of late pathologic changes (in 39 out of 70). Disorders in odontogeny, eruption of the teeth and occlusion were observed. Primary and secondary loss of teeth did also occur. Our results show the necessity to inform both the young patients and their parents about the high incidence of late changes after jaw fractures in childhood. An effective recall-system is required in order to diagnose and treat such changes as soon as possible.

Child↗
PubMed1988

Results in the use of extracorporeal piezoelectric lithotripsy (EPL) for treatment of urinary calculi.

The Piezolith 2200 as an extracorporeal shock wave lithotripter uses piezoelectrically generated, high-energy sonic impulses for treatment of urinary calculi; the shock wave generator is self-focussing. Localization of concrements is performed by means of ultrasound imaging. Treatment with the Piezolith 2200 is painless for the patient and thus possible without anesthesia and analgesia. We report on 806 cases of treatment involving a total of 572 kidneys in 567 patients (561 adults, 6 children) suffering from calculi of various sizes in the renal pelvis (n = 126), calculi in the calyces (n = 384), partial (n = 24) or full (n = 19) staghorn calculi, as well as calculi in the upper part of the ureter (n = 19). In 88% of these cases the concrements could be removed completely. Since cardiac activity is not influenced by piezoelectrically generated high-energy impulses, this procedure is particularly suited to the treatment of patients with heart problems.

Adult↗
PubMed1983

[Bladder and urethral injuries - report of experiences].

Injuries of bladder and urethra cause diagnostic and therapeutic problems to urologists and surgeons. A retrospective study of 98 patients from 1975 until 1982 with pelvic trauma and damage of the lower urinary tract is presented concerning etiology, mechanism of accident and therapeutic possibilities, as well as the analysis of 24 patients with anterior urethra damage. In all 38 cases with ruptured bladder operation was performed. 66 patients with posterior urethra damage were treated with regard to their general status. In this study conservative management with catheter or cystostomy seems to be more favourable in posterior urethra damage than primary reconstructions especially when considering the rate of urethral structure. Furthermore problems of posttraumatic difficulties with sexual potency are discussed.

Adolescent↗
PubMed1976

Does the renin-angiotensin system contribute to the vascular lesions in renal hypertensive rats?

1. Renal hypertensive rats with a normal or suppressed activity of the renin-angiotensin system develop vascular lesions which are similar to those observed in spontaneously hypertensive rats on high sodium diet. 2. Exposure of a vascular bed to high blood pressure results in a rapid damage of the vascular wall, irrespective of the state of the renin-angiotensin system.

Angiotensin II↗