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Biomedical subjects

R Rahmanzadeh

Publications and source records attributed to R Rahmanzadeh.

At least 19 recordsLinked to original sources
PubMed2005

The Linderniaceae and Gratiolaceae are further lineages distinct from the Scrophulariaceae (Lamiales).

The Lamiales are one of the largest orders of angiosperms, with about 22,000 species. The Scrophulariaceae, as one of their most important families, has recently been shown to be polyphyletic. As a consequence, this family was re-classified and several groups of former scrophulariaceous genera now belong to different families, such as the Calceolariaceae, Plantaginaceae, or Phrymaceae. In the present study, relationships of the genera Craterostigma, Lindernia and its allies, hitherto classified within the Scrophulariaceae, were analyzed. Sequences of the chloroplast trnK intron and the matK gene (approximately 2.5 kb) were generated for representatives of all major lineages of the Lamiales and the former Scrophulariaceae. Bayesian and parsimony analyses revealed two isolated lineages, one of which consists of Lindernia and its allies, the other of Gratiola and allies. Gratiola was previously assumed to be related to Lindernia and was therefore included here. It is proposed to treat the two clades as separate families, Linderniaceae and Gratiolaceae. For the Linderniaceae, several morphological synapomorphies exist in addition to molecular data, such as conspicuous club-shaped stamen appendages.

Bayes Theorem↗
PubMed2001

Inhibition of mitogen-activated protein kinase kinase induces apoptosis of human chondrocytes.

We previously have reported that the mitogen-activated protein kinase (MAPK) pathway is stimulated by adhesion of human chondrocytes to anti-beta(1)-integrin antibodies or collagen type II in vitro. These mechanisms most likely prevent chondrocyte dedifferentiation to fibroblast-like cells and chondrocyte death. To investigate whether this pathway plays an essential role for the differentiation, phenotype, and survival of chondrocytes, we blocked mitogen-activated protein kinase/extracellular signal-regulated kinase (Erk) (MEK), a kinase upstream of the kinase Erk by using U0126. Exposure of chondrocytes to U0126 caused activation of caspase-3 in a dose-dependent manner. Western blot analysis with an antibody specific for dually phosphorylated Erk shows that collagen type II induced phosphorylation of Erk1/2 was specifically blocked by U0126 in a dose-dependent manner. Immunohistochemical analysis showed that treated chondrocytes were caspase-3 positive. In treated chondrocytes, the cleavage of 116-kDa poly(ADP-ribose)polymerase resulted in the 85-kDa apoptosis-related cleavage fragment and was associated with caspase-3 activity. Analysis by electron microscopy showed typical morphological signs of apoptosis, such as crescent-shaped clumps of heterochromatin, and a degraded pericellular matrix. Thus, these results indicate that the MEK/Erk signal transduction pathway is involved in the maintenance of chondrocytes differentiation and survival. These data stimulate further investigations on the role of mitogen-activated protein kinase pathways in human chondrocytes.

Apoptosis↗
PubMed2001

[Madreporic hydroxyapatite granulates for filling bone defects].

Two macrocrystalline madreporic granular hydroxyapatite implants of different size range (single crystal size within both implants 1-3 microns) were implanted for 7, 28, 84 and 168 days into the trabecular bone of the distal femur epiphysis of rabbits. Both materials were investigated histologically. For testing of granular materials a new animal model has been developed. The drill hole was closed by reimplantation of an autologeous chondrocortical tissue slice to prevent loss of particles into the knee-joint. Both of the granular materials tested developed increasing bone bonding from the 7th day on to outer surfaces and pore surfaces. The degradation of both of the materials affected the superficial implant layers in soft-tissue interfaces exclusively and was mainly due to passive processes, e.g. leaching, fragmentation of granules after crack-production, particulate degradation and subsequent phagocytosis of liberated implant particles by macrophages and foreign body giant cells. Zones of superficial implant degradation were bonded partially to bone a second time. A possible low-degree, active superficial degradation by foreign body giant cells is discussed. Osteoclasts of typical morphology as being observed on other hydroxyapatite implant surfaces were not demonstrated. This was related to the low degradation rate of the implants. Both of the granular materials tested are useful in filling bone defects. A guided tissue regeneration due to partial implant degradation and subsequent bone formation seems to be impossible since the degradation rate of the materials is too low.

Animals↗
PubMed1999

Signal transduction by beta1 integrin receptors in human chondrocytes in vitro: collaboration with the insulin-like growth factor-I receptor.

We have examined the mechanism by which collagen-binding integrins co-operate with insulin-like growth factor-I (IGF-I) receptors (IGF-IR) to regulate chondrocyte phenotype and differentiation. Adhesion of chondrocytes to anti-beta1 integrin antibodies or collagen type II leads to phosphorylation of cytoskeletal and signalling proteins localized at focal adhesions, including alpha-actinin, vinculin, paxillin and focal adhesion kinase (FAK). These stimulate docking proteins such as Shc (Src-homology collagen). Moreover, exposure of collagen type II-cultured chondrocytes to IGF-I leads to co-immunoprecipitation of Shc protein with the IGF-IR and with beta1, alpha1 and alpha5 integrins, but not with alpha3 integrin. Shc then associates with growth factor receptor-bound protein 2 (Grb2), an adaptor protein and extracellular signal-regulated kinase. The expression of the docking protein Shc occurs only when chondrocytes are bound to collagen type II or integrin antibodies and increases when IGF-I is added, suggesting a collaboration between integrins and growth factors in a common/shared biochemical signalling pathway. Furthermore, these results indicate that focal adhesion assembly may facilitate signalling via Shc, a potential common target for signal integration between integrin and growth-factor signalling regulatory pathways. Thus, the collagen-binding integrins and IGF-IR co-operate to regulate focal adhesion components and these signalling pathways have common targets (Shc-Grb2 complex) in subcellular compartments, thereby linking to the Ras-mitogen-activated protein kinase signalling pathway. These events may play a role during chondrocyte differentiation.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Tissue engineering of biphasic joint cartilage transplants.

In isolated posttraumatic or idiopathic joint defects the chondral layers and adjacent subchondral spongy bone are usually destructed. For regeneration we suggest the in vitro formation of a cartilage-coated biomaterial carriers (biphases) in order to fill the correspondingjoint defects. In this study Biocoral, a natural coralline material made of calcium carbonate, and calcite, a synthetic calcium carbonate, were used as supports for the cultivation of bovine chondrocytes in a three-dimensional polymer fleece. The cell-polymer-structure was affixed to the biomaterial with a fibrin-cell-solution. The artificial cartilage formed a new matrix and fused with the underlying biomaterial. The results indicate a promising technical approach to anchor tissue engineered cartilage in joint defects.

Animals↗
PubMed1999

Presence and distribution of collagen II, collagen I, fibronectin, and tenascin in rabbit normal and osteoarthritic cartilage.

OBJECTIVE: To investigate changes in the composition of articular cartilage matrix during the development of experimental osteoarthritis (OA), collagen type II, collagen type I, and the noncollagenous proteins fibronectin and tenascin were studied in normal and osteoarthritic cartilage of rabbits. METHODS: OA of the knee joint was induced by a medial meniscectomy and section of the medial collateral ligament and anterior cruciate ligament. Frozen sections of rabbit normal and OA cartilage were stained with monoclonal antibodies against collagen type II, collagen type I, fibronectin, and tenascin. RESULTS: Collagen II manifested a decreased interterritorial staining and seemed to increase territorially in the deeper zones of the OA cartilage. Collagen I was found in normal cartilage as a thin layer covering the surface and also in OA fibrillated cartilage. Fibronectin was present in normal and OA cartilage. Whereas a layer covered the normal cartilage, a thicker layer was observed in OA cartilage. In addition, changes in fibronectin distribution from the pericellular to the interterritorial matrix were observed. Tenascin was also found in normal cartilage matrix, particularly in the territorial and interterritorial matrix of the deeper zones. It showed an increased staining intensity in fibrillated cartilage, in the pericellular matrix of the upper chondrocytes, and on the surface lining in OA cartilage. CONCLUSION: Collagen type II deposition seems to increase in the deeper cartilage zones during the osteoarthritic process, as a sign of tissue repair response. Collagen type I, fibronectin, and tenascin show enhanced deposition in the upper, fibrillated osteoarthritic cartilage, suggesting a common mediator controlled pathway.

Animals↗
PubMed1998

[Comparison of internal fixation methods for the symphysis in multi-directional dynamic gait simulation].

For the stabilization of the ruptured pubic symphysis, rigid forms of fixation such as plate osteosynthesis and flexible fixations such as wire loops or PDS banding have been recommended. All methods have only been tested by static unidirectional loading until failure of the system. By this experimental arrangement Ecke and Hofmann found comparable results for flexible and rigid methods of internal stabilization of the pubic symphysis. They preferred flexible methods to maintain mobility of the symphysis and to prevent symphyseal fusion. We tested dynamic compression plate osteosynthesis, reconstruction plate osteosynthesis, wire loops and PDS banding for internal fixation of injured pubic symphysis in a dynamic multidirectional experimental arrangement simulating gait conditions. The specimens were loaded with 85 N in vertical (y-) direction and 34 N in sagittal (z-) direction, which represent 50% of the forces acting at the pubic symphysis during walking and with a frequency of 1.5 Hz over 55,500 loads simulating the conditions over a 6-week mobilization period. Loading with 100% of the acting forces (corresponding to full weight bearing mobilization) led to early failure of the system. Our experimental analysis showed that neither wire loops nor PDS banding is able to stabilize the ruptured pubic symphysis, even immediately after fixation before loading. During the tests instability increased until failure of the system due to cutting of the bone or breaking of the wires or PDS banding. Success of plate osteosynthesis was dependent on the initial stability of the fixation. Overwinding of the screws, as in osteoporotic bone, lead to increasing loosening during repeated loading, whereas primary stable fixation of the screws was almost completely maintained during the test. In consequence, neither wire loops nor PDS banding should be used for stabilization of injured pubic symphysis if early mobilization with partial weight bearing is desired. Plate osteosynthesis (DC or reconstruction plate) tolerates early half weight bearing in patients with "open-book" injury only if safe screw fixation is guaranteed.

Biomechanical Phenomena↗
PubMed1996

[Long-term results of surgical and conservative treatment of ruptures of the long biceps tendon].

INTRODUCTION: The therapeutic concept for rupture of the long biceps tendon continues to be controversially discussed. Various operative procedures compete with mostly unstructured conservative ones. QUESTION INVESTIGATED: a) Is operative therapy of the long biceps tendon rupture superior to the conservative treatment? b) For which group of patients should the operative or the conservative therapy be recommended? PATIENTS AND METHOD: The value of operative versus conservative therapy was examined based on a collective of 43 ruptures (39 patients), 31 operatively and twelve conservatively treated. The investigation comprised the following: 1) the subjective evaluation of the long-term result by the patient, 2) a thorough clinical examination including the function of the shoulder and the elbow joint and 3) an isokinetic force and endurance test on Cybex II. The results of the follow-up were evaluated by a score. RESULTS: It was found that very good but also poor results can be achieved with both operative and conservative therapy, the good results distinctly predominating in the operated collective. Statistically significant differences could not be detected because of the small number of cases and the relatively large variation range. Good results after conservative therapy require a differentiated rehabilitation program corresponding to the normal course followed after operative treatment. CONCLUSION: Since results tended to be better for the operated collective in our study, we recommend a surgical procedure for active younger patients. It seems to be of decisive importance to perform the operation as early as possible and to achieve optimal tension of the muscle by refixation of the tendon.

Adult↗
PubMed1996

[Biomechanics of the pubic symphysis. Which forces lead to mobility of the symphysis in physiological conditions?].

For estimation of the loads of fixation devices, physiological movements and acting forces at the symphysis pubis are examined. Experimentally, Walheim determined the movements of the pubic symphysis under physiological conditions (one-leg stance, walking): there is no effective mobility in the horizontal direction. During the one-leg stance he observed symphyseal mobility of up to 2.6 mm (Phi 1.2 mm) in the vertical direction and 1.3 mm (Phi 0.6 mm) in the sagittal direction. During walking he found symphyseal mobility of up to 2.2 mm (Phi 0.9 mm) in the vertical direction and 1.3 mm (Phi 0.6 mm) in the sagittal direction. Until now the forces leading to symphyseal mobility have not been estimated either experimentally or mathematically. In our experimental study we examined ten fresh cadaver anterior pelvic rings by means of a multidirectional force-mobility measurement. Maximal physiological movements, as determined by Walheim, were increasingly induced in ten equal steps, and the forces required were measured for every single step. Out of the resulting force-mobility curves for the ten cadaver specimens the mean force required (with standard deviation) was calculated for each of the ten measure points, separately for the vertical (y-) direction and sagittal (z-) direction. The values were graphically transferred, and a regression curve was created. This curve allows the acting force to be estimated for every movement of the pubic symphysis: During the one-leg stance the mean force to induce mean mobility is 169 N in vertical direction and 148 N in sagittal direction; for maximal mobility a force of 398 N in the vertical direction and 148 N in the sagittal direction is necessary. During walking, the force required to induce mean movement of the symphysis pubis is 120 N in the vertical direction and 68 N in the sagittal direction; for maximal mobility 333 N is required in the vertical direction and 136 N in the sagittal direction. For mobilization of patients with a symphyseal rupture (type Tile B 1) with partial weight-bearing, neutralization of the mean acting forces during the one-leg stance (169 N in the vertical direction, 68 N in the sagittal direction) must be achieved by an adequate fixation device. In cases where full weight bearing is desirable, such as in patients with limited compliance, stability can only be reached by neutralization of the maximal acting forces during walking (333 N in the vertical direction, 136 N in the sagittal direction).

Adult↗
PubMed1995

Relevance of carbohydrate-deficient transferrin as a predictor of alcoholism in intensive care patients following trauma.

Every second traumatized patient is a chronic alcoholic. Chronic alcoholics are at risk due to an increased morbidity and mortality. Reliable and precise diagnostic methods for detecting alcoholism are mandatory to prevent posttraumatic complications by adequate prophylaxis. The patient's history, however, is often not reliable, and conventional laboratory markers are not sensitive or specific enough. The aim of this study was to investigate whether carbohydrate-deficient transferrin (CDT) is a sensitive and specific marker to detect alcoholism in traumatized patients. One hundred and five male traumatized patients or their relatives gave their written informed consent to participate in this institutionally approved study. All patients were transferred to the intensive care unit after admission to the emergency room, followed by surgical treatment. Diagnostics included an alcoholism-related questionnaire, conventional laboratory markers (mean corpuscular volume, gamma-glutamyltransferase, aspartate aminotransferase, and alanine aminotransferase), and CDT sampling (microanion-exchange chromatography, turbidimetry, and radioimmunoassay, respectively). Only patients in whom a reliable history could be obtained were included. Alcoholism was diagnosed if the patients met the Diagnostic and Statistical Manual of Mental Disorders criteria for chronic alcohol abuse or dependence. The administration of fluids before CDT sampling was carefully documented. Patients did not differ significantly regarding age, Trauma and Injury Severity Score, and Acute Physiology and Chronic Health Evaluation score. The sensitivity of the CDT research kit was 70% and of the commercially available kit CDTect was 65%. Early sampling in the emergency room and before administration of large volumes of fluid increased the sensitivity to 83% for the CDT research kit and 74% for CDTect, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

[Long-term outcome after conservative treatment of pelvic ring injuries and conclusions for current management].

Until the early eighties conservative treatment was common even for unstable pelvic fractures. The long-term results of 114 non-operatively treated patients who had suffered a pelvic fracture (68 type A, 20 type B, 26 type C according to the classification of the ASIF) have been examined after an average time of 7.1 years after injury. 60% of cases with a stable injury of the pelvis (type A) did not suffer of any complaint. The remaining patients stated moderate pain. After conservative treatment of type B pelvic injuries 55% complained of pain or showed an impaired functional result. Former vertical-shear fractures (type C) showed worse results than type B pelvic injuries: only 15% did not suffer of any pain and 10% had no functional deficit. Patients with unstable pelvic fracture localized pain mainly in the lumbo- or iliosacral region. Radiological and CT findings suggest arthrosis, partial ancylosis and incomplete reduction of the fracture as possible reasons for unsatisfactory clinical results. As consequence of these results we nowadays proceed extended radiological examinations (a.-p.-, inlet-, outlet-views, CT) and operative reduction and internal stabilization (ORIF) of all unstable pelvic fractures.

Activities of Daily Living↗
PubMed1994

[Herpes simplex digitalis--an important differential diagnosis of paronychia].

Herpes simplex infection of the hand is often falsely diagnosed as a pyogenic paronychia or felon and treated as such, because the clinical picture is not known and pathogen isolation is difficult. However, the surgical treatment of herpes digitalis is contraindicated, since it promotes the development of superinfections and triggers recurrence. The pathogen can be isolated in cell cultures prepared from the vesicle contents or a smear from the vesicle base. Serological antibody testing is unreliable. Topical application of Acyclovir cream (Zovirax) is the treatment of choice.

Acyclovir↗
PubMed1994

[Using of a Wagner stem in revision-arthroplasty following loosening of a total hip endoprosthesis].

During a three-year period to 50 patients a Wagner femoral revision endoprosthesis was implanted. The mean age of the patients was 67.5 years. In 39 patients replacement of an endoprosthesis was involved, in 7 patients the indication was fracture in the area of the endoprosthesis, 4 patients were operated for other reasons. Of 44 patients, who were operated at least 12 months ago, 33 were checked. Sixteen patients were classified according to Harris' score as very good, 9 as good and in 4 the result was satisfactory or poor. Wagner's revision shank is suitable in particular in damage of the proximal femur, where in case of firm distal anchoring and early ability to burden the extremity proximally, marked new formation of bone was observed with restoration of the pipe-shaped bone structure.

Aged↗
PubMed1992

Treatment of extensive aseptic defects in old Achilles tendon ruptures: methods and case reports.

Defect bridging is still problematic in the secondary treatment of Achilles tendon ruptures. Smaller defects can be treated without problems by the well-known standardized methods, whereas other methods have to be applied for treating larger defects. Free transplants with autogenous or exogenous material should be mentioned in this context. Complications are more likely to occur with exogenous material, free transplants from the fascia lata require an additional intervention to remove the transplant from another localization. These methods cannot be applied to achieve reliable restoration of continuity for defects with a length of 10 cm. Therefore, in these special cases, we carry out the tendon transplantation with a free tendon-muscle graft from the triceps surae muscle. We achieved reliable restoration of continuity with complication-free healing of the free transplant in, up to now, three cases, in association with the formation of a strong, functionally high grade scar plate in the area of the tendon.

Achilles Tendon↗
PubMed1991

[Modified after care following primary management of rupture of the Achilles tendon].

During the period ranging from 1975 to 1988, 169 Achilles tendon ruptures were operated on in the Department of Traumatology and Reconstructive Surgery of Steglitz Medical Center, Free University of Berlin. The majority of these ruptures, i.e. 149 cases, were due to sports injuries. In order to comply with our patients' wish for quick rehabilitation, we have altered our follow-up treatment concept since 1982. The surgical technique remained the same in the form of a Bunnell suture with wire or absorbable suture material. There was an initial post-operative immobilization for five to seven days in a dorsal femoral plaster splint at a 30 degree bending position. The ankle joint was immobilized in a neutral position from the start. After approximately one week, the lower leg was put in a walking cast in a neutral position. The patients were allowed to put full load on the leg. After an additional four weeks, the cast was removed and functional follow-up treatment started. The two patient collectives that were compared did not significantly differ with regard to age structure and accident mechanisms or accident causes. Changes in the follow-up treatment resulted in a marked reduction in duration from 14 to 10 weeks. Standing on the toes was likewise possible after 10 weeks. Sports activities could be resumed after four instead of six months, as before. The postoperative rate of complications was low. There were only 10 infections in the total patient collective, one being a deep-wound infection requiring surgical intervention.(ABSTRACT TRUNCATED AT 250 WORDS)

Achilles Tendon↗
PubMed1991

[Surgical treatment of acromioclavicular joint injury].

The acromioclavicular joint plate according to Rahmanzadeh allows the safe retention of the reset acromioclavicular joint in stage Tossy III and in exceptional cases also in stage Tossy II traumata when simultaneous early functional post-treatment is done from the first postoperative day on. The clinical results obtained after follow-up examinations of 53 of the 83 patients treated in this way were mostly good or very good. Perfect radiological results were obtained in 50% of these patients; 40% showed a slight subluxation and 10% a marked but pain-free subluxation.

Acromioclavicular Joint↗
PubMed1990

[Corrective osteotomy of the head of the tibia in primary and secondary gonarthrosis--a para-articular operation].

The corrective osteotomy at the head of the tibia with degenerative or posttraumatic medial or lateral gonarthrosis and misalignment of the axis is until today a procedure to be recommended prior to a total or partial implantation of an endoprosthesis. The main advantage in comparison with a mono-condylar prosthesis is the removal of the causal damage of the misalignment. Old age and general relative risks are no contraindications to this procedure. The method used most in the operative technique is the correction of valgus deviation at the head of the tibia after osteotomy of the fibula with stabilization with a fixateur externe. On the whole, the risk of the operation is very low, the main complication is the lesion of the nervus peronaeus. With regard to the subjective result from the patients point of view the most important aspect is the relief or disappearance of pain, which is reached in comparison with a partial prosthesis of the knee joint with similar security. About two thirds of the patients are subjectively contempt with the results of the operation within a time of three to five years.

Adult↗