Biomedical subjects

J Korner

Publications and source records attributed to J Korner.

At least 19 recordsLinked to original sources

PubMed2005

The influence of bone allograft processing on osteoblast attachment and function.

In order to assess the influence of eight different sterilisation and disinfection methods for bone allografts on adhesion, proliferation, and differentiation of human bone marrow stromal cells (BMSC), cells were grown in culture and then plated onto pieces of human bone allografts. Following processing methods were tested: autoclavation (AUT), low-temperature-plasma sterilisation of demineralised allografts (D-LTP), ethylene oxide sterilisation (EtO), fresh frozen bone (FFB), 80 degrees C-thermodisinfection (80 degrees C), gamma-irradiation (Gamma), chemical solvent disinfection (CSD), and Barrycidal-disinfection (BAR). The seeding efficiency was determined after one hour to detect the number of attached cells before mitosis started. The cell viability was determined after 3, 7, and 21 days. Tests to confirm the osteoblastic differentiation included histochemical alkaline phosphatase staining and RT-PCR for osteocalcin. Human BMSC showed greatest attachment affinities for D-LTP-, 80 degrees C-, and CSD-allografts, whereas less cells were found attached to AUT-, EtO-, FFB-, Gamma-, and BAR-probes. Cell viability assays at day 3 revealed highest proliferation rates within the FFB- and 80 degrees C-groups, whereas after 21 days most viable cells were found in D-LTP-, 80 degrees C-, CSD-, and Gamma-groups. BAR-treatment showed a considerably toxic effect and therefore was excluded from all further experiments. Highest AP-activity and gene expression of osteocalcin were detected in the D-LTP-group in comparison with all other groups. In summary, our results demonstrate that cell adhesion, final population, and function of BMSC are influenced by different disinfection and sterilisation methods. Therefore, processing-related alterations of BMSC-function may be important for the success of bone grafting. The experimental setup used in the present work may be useful for further optimisation of bone allograft processing.

Alkaline Phosphatase↗

PubMed2005

[Surgical treatment of type I capitellar-humeral fractures using the Henry ventral approach approach. Short- and medium-term results].

Capitellar fractures are rare. Despite adequate surgical treatment, patients suffer frequently from limited range of motion, osteonecrosis, and neurological deficits. The purpose of this retrospective study was to evaluate short- and medium-term surgical results in seven patients who had type I capitellar fractures according to Bryan and Morrey. All patients were treated via an anterior approach, according to Henry, and open reduction and internal fixation with two screws. Seven patients were examined clinically, neurologically, and radiologically after 10-65 months. The fracture healed in all patients. None of the patients had a neurological deficit. According to the Morrey Score, five of seven patients had an excellent or good functional result. Open reduction and internal fixation with two screws via the Henry approach is a suitable option for surgical treatment for type I capitellar fractures.

Adult↗

PubMed2004

[Monteggia injuries in adults: Critical analysis of injury pattern, management, and results].

BACKGROUND: Complications, revision surgery, and unsatisfactory functional results after operative management of Monteggia fractures are frequent. Moreover, hardly any studies exist that deal exclusively with the therapeutic concept for adults. PATIENTS AND METHODS: Between January 1988 and December 2001, 68 patients with Monteggia fractures or equivalent injury were surgically treated. A total of 49 patients could be followed up after 83 months (25-176). Fracture type was assessed according to Bado's classification, functional results according to the Mayo elbow performance score, and the extent of osteoarthritis based on the criteria of Baird and Johnson. RESULTS: The median age of the follow-up patients was 38 years (18-89, 31 men, 18 women). Corresponding to Bado's classification the following injuries were observed: 18 cases of type 1, 22 of type 2, 5 of type 3, and 4 cases of type 4. After surgical intervention, 14 patients achieved "very good", 21 "good", 9 "satisfactory", and 5 "poor" results. Of the 14 patients with either "satisfactory" or "poor" results, 9 manifested a type 2 injury. Complications requiring revision surgery occurred in 14 patients and complications not requiring revision in another 14. Severe osteoarthritic changes in the humeral or radioulnar joint were observed in 4 cases. CONCLUSIONS: Monteggia fractures in adults are fraught with complications despite good functional results in the majority of cases. The patient should be made aware early on of the risk of residual functional deficits and the need for further surgical intervention.

Adolescent↗

PubMed2004

[Are angle-fixed implants with elastic properties advantageous for the internal fixation of proximal humerus fractures?].

There is a recent interest for the use of angle-fixed plates in the management of proximal humerus fractures. Rigid implants might be associated with an increased risk of cutting-out. In order to analyse the potential beneficial effects of the implant elasticity on fracture fixation, the biomechanical properties of a rigid and an elastic angle-fixed plating system were assessed in an experimental study. An unstable fracture of the surgical neck was created in 8 pairs of human humeri. Specimens were subjected to axial loading and torque. Stiffness, subsidence and load to failure were assessed. The implant with elastic properties was characterized by a lower torsional stiffness and a higher subsidence during axial loading and torque. This implant failed at lower loads than the rigid implant did. Elastic implant properties of angle-fixed plates have shown not to be advantageous for the management of fractures of the proximal humerus.

Bone Plates↗

PubMed2003

Proximal humeral fractures: how stiff should an implant be? A comparative mechanical study with new implants in human specimens.

BACKGROUND: The objective of this study was to determine the in vitro characteristics of the clinically used and newly developed implants for the stabilization of proximal humeral fractures under static and cyclic loading. The goal was to optimize implant stiffness for fracture stabilization even in weak bone stock. METHODS: In a laboratory study using 35 fresh human humeri, the specimens were randomized into 5 groups, which included the clinically used humerus T-plate (HTP), the cross-screw osteosynthesis (CSO), the unreamed proximal humerus nail with spiral blade (UHN), the recently developed Synclaw Proximal Humerus Nail (Synclaw PHN) and the angle-stable Locking Compression Plate Proximal Humerus (LCP-PH). The implant stiffness was determined for three clinically relevant load cases: axial compression, torsion and varus bending. In addition, a cyclic varus-bending test was performed to determine the implant properties under cyclic loading. RESULTS: In contrast to a rather elastic and minimally invasive implant(LCP-PH), the conventionally designed ones (Synclaw PHN, CSO, HTP, UHN) showed rather high stiffness values under static loading. In cyclic loading, a strong decrease in stiffness ( p<0.05) was found for the rigid implants HTP and UHN. In comparison with the other implants, only the elastic implant (LCP-PH) showed a significantly lower load reduction in a weak bone stock (17+/-6.2%). CONCLUSION: The high initial stiffness of rigid implants led to an early loosening and failure of the implant-bone interface under cyclic loading. Implants with low stiffness and elastic characteristics, however, appear to minimize the peak stresses at the bone-implant interface, making them particularly suitable for fracture fixation in osteoporotic bone.

Adult↗

PubMed2003

[Tibial plateau fracture--biodegradable bonecement-augmentation].

Between October 1996 and January 1999,29 patients (f:16,m:13,age: 22-86) with fractures of the lateral tibial plateau were operated on arthroscopic,fluoroscopic control or were treated with open reduction and internal fixation. 15 of them were retrospective and 14 prospective analysed. The metaphyseal defect after elevation of the depressed fragment was augmented in 11 cases with autologous spongeous bone grafting,in 9 cases with biodegradable bone cement (Norian SRS). Augmentation was unnecessary in 9 cases. The results according to the Lysholm score and the radiological results were good or excellent. Concerning the kind of augmentation no difference was noted. In the Norian SRS-group the duration of postoperative treatment was shorter than in the other group. The duration of partial weight bearing was shorter too. The results of the present study suggest that an injectable calcium phosphate cement may be a competent material for augmentation in lateral tibial plateau fractures because of the application form and the initial high mechanical stability.

Adult↗

PubMed2003

Effects of agouti-related protein on metabolism and hypothalamic neuropeptide gene expression.

The hypothalamic melanocortin system regulates feeding in part through interaction of the appetite stimulating peptide, agouti-related protein (AGRP), and the anorectic peptide, alpha-melanocyte stimulating hormone, a peptide derived from the pro-opiomelanocortin (POMC) polyprotein. Central administration of AGRP induces hyperphagia and increased gain in body weight in rodents, but may also exert metabolic effects even when hyperphagia is prevented. In the present studies, the effects of AGRP on hypothalamic neuropeptide gene expression and metabolism were examined in the rat. Central administration of AGRP for 3- and 7-day periods resulted in hyperphagia, increased body weight and increased plasma leptin and insulin concentrations compared to saline-injected controls. Hypothalamic concentrations of Pomc mRNA were also increased by 27% and 44% (in 3- and 7-day experiments, respectively). The hypothalamic concentration of Agrp mRNA was unchanged after 3 days, but was significantly decreased by 33% after 7 days of AGRP infusion. To determine if these changes were dependent upon AGRP-induced hyperphagia, pair-fed rats with restricted food intake receiving central administration of AGRP were also studied. In the absence of hyperphagia, intracerebralventricular administration of AGRP caused significant increases in plasma leptin and insulin concentrations (two-fold and 1.5-fold, respectively) and fat pad mass. A significant increase in hypothalamic Pomc mRNA concentrations was not detected in pair-fed rats. In contrast, Agrp mRNA concentrations remained suppressed by 45% in the pair-fed group after 7 days of AGRP infusion despite equal body weight compared to saline controls. The ratio of hypothalamic Pomc to Agrp mRNA was elevated two-fold in ad libitum and pair-fed AGRP-injected rats, which is consistent with increased stimulation of central melanocortin signalling pathways. Thus, central administration of AGRP exerts changes in hypothalamic neuropeptide gene expression and metabolic effects that are independent of the effects on food intake and body weight.

Agouti-Related Protein↗

PubMed2002

[Age- and gender-related distribution of bone mineral density and mechanical properties of the proximal humerus].

PURPOSE: To evaluate age- and gender-related mechanical properties and bone mineral density (BMD) of the proximal humerus at different levels and regions. MATERIALS AND METHODS: Mechanical indentation testing, DXA, QCT, pQCT and the radiogrammetry (Cortical Index, CI) were carried out in 70 freshly harvested humeri from 46 human cadavers (23 females, 23-males; median age 70.5 years). RESULTS: In the female group, a high correlation between age and BMD was found (rho = 0.62 to -0.70, p < 0.01) with statistically significant differences between specimens of patients 69 years or younger, and 70 years or older (p < 0.05). In the group of female specimens of age 70 years or older, BMD values were found to be significantly lower compared to their male counterparts (p < 0.05). Regardless of the specimen's age, the highest BMD and bone strength were found in the proximal aspect and in the medial and dorsal regions of the proximal humerus. CONCLUSION: These findings provide an insight into the fracture mechanism of the proximal humerus and should be the basis for designing structure-oriented implants with improved implant-bone stability in osteoporotic patients.

Absorptiometry, Photon↗

PubMed2001

[Perioperative local instillation of ropivacaine for postoperative pain relief after surgery on extremities].

INTRODUCTION: The relief of postoperative pain remains one of the most important goals for adequate surgical patient care. METHODS: Prospective, randomised, double-blinded study, including 118 patients (67 M;/ 51 F; median age 43 years, min. 18, max. 74). Two groups were formed. In the verum group a wound instillation with ropivacaine was performed, in the control group not. Intensity of pain, demand for analgesics and satisfaction of the patient were evaluated postoperatively. In 10 patients ropivacaine plasma levels were measured. RESULTS: Significant postoperative pain relief and a decrease in analgesic consumption were found on instillation of ropivacaine. Compared to the control group, patients receiving ropivacaine were significantly more satisfied with the postoperative pain management. Potential toxic plasma levels were not found. CONCLUSION: By the presented method, the surgeon actively contributes to a significant reduction in postoperative pain and analgesic consumption. Furthermore, the patient's benefit is reflected by higher satisfaction with the pain management. Complications due to toxic plasma levels are not seen.

Adolescent↗

PubMed2001

[Crossed screw osteosynthesis of proximal humerus fractures].

Between March 1997 and October 1999 thirty-one patients with displaced proximal humeral fractures were treated with crossed screw osteosynthesis. Insertion of the screws was realized by using a deltoideo-pectoral approach placing the screws anteriorly and posteriorly in a crossed manner from the distal fragment into the humeral head. Additionally, in all two-part-fractures a tension band was applied. In all three-part-fractures, the greater tuberosity was reattached by additional screws. In 21 patients (14 female, 7 male, median age 62 years, 18-86) a clinical and radiological follow-up (median 18 months, 10-29) was obtained. Fractures were classified as two-part-fractures in 10 patients and as three-part-fractures in 11 patients. According to the Constant-Score, "excellent" and "good" results were achieved in 15 patients, "moderate" results were found in 3 patients. However, in 3 patients results were only "poor" (1 two-part-, 2 three-part-fractures). The complication rate was 29% (premature hardware removal due to head perforation in 3 cases; humeral head necrosis necessitating prosthetic replacement in 2 patients; secondary displacement in 1 case). Crossed screw osteosynthesis represents an justified alternative in the surgical treatment of displaced proximal humeral fractures permitting early functional therapy.

Adolescent↗

PubMed2001

Fracture-dislocations of the elbow joint--strategy for treatment and results.

Between January 1993 and December 1996, 41 patients with fracture dislocation of the elbow joint were treated in our department. In 28 patients (median age 46 years, range 15-77 years; 16 male, 12 female), a clinical and radiological follow-up was obtained after median 34 months (range 12-59 months). In addition to the humero-ulnar dislocation, isolated fractures were present in 13 patients and combined fractures in 15 (all with involvement of the radial head). Primary neurological deficits were found in 7 and open fractures in 3 patients. In 7 patients, primary definitive surgical therapy was carried out by open reduction and internal fixation. A two-step surgical management (initial closed reduction and immobilization, 5 patients with external fixator, 7 with plaster; secondary open surgical procedure) was performed in 12 and conservative treatment in 9 patients. According to the Leipzig Elbow Score, taking subjective, clinical and radiological criteria into consideration, 4 patients achieved 'excellent' and 5 patients a 'good' result. Ten patients were scored 'moderate' and 9 'poor'. The rate of secondary complications necessitating revision was 36%. Poor results were primarily caused by extensive initial soft-tissue damage, delayed definitive surgical therapy, and ectopic heterotopic ossification. In contrast, fracture localization and degree of arthrosis were not of significant importance for the final outcome. In fracture dislocations, the goal is a primary definitive surgical treatment aiming for early postoperative physiotherapy.

Adolescent↗

PubMed2001

An update on the science and therapy of obesity and its relationship to osteoarthritis.

Obesity and osteoarthritis are two commonly encountered clinical problems that can lead to significant physical and emotional disability. This report examines the association between obesity and osteoarthritis, and discusses potential mechanisms by which obesity influences osteoarthritis. Special attention is devoted to reviewing the molecular and genetic mechanisms that underlie the development of clinical obesity. Improved understanding of obesity will hopefully lead to improved treatment and subsequent amelioration of this important risk factor for osteoarthritis.

Humans↗

PubMed2001

Arthroscopic-assisted simultaneous reconstruction of the posterior cruciate ligament and the lateral collateral ligament using hamstrings and absorbable screws.

Arthroscopic-assisted simultaneous reconstruction of the posterior cruciate ligament (PCL) and the lateral collateral ligament (LCL) using hamstring tendon grafts is described. The femoral tunnel is drilled through an incision over the medial femoral condyle and the tibial tunnel through the same skin incision used for harvesting the tendon graft. PCL reconstruction is performed using a 4-strand hamstring tendon graft and absorbable screw fixation. The tendon of the semitendinosus muscle of the uninvolved knee is used as a lateral loop for LCL reconstruction. After pulling the transplant through the fibular head, femoral fixation of the loop is made with an absorbable screw.

Absorbable Implants↗

PubMed2001

Leptin regulation of Agrp and Npy mRNA in the rat hypothalamus.

Agouti-related protein (AGRP) is synthesized in the same neurones in the arcuate nucleus as neuropeptide Y (NPY), another potent orexigenic peptide. AGRP antagonizes the action of alpha-melanocyte stimulating hormone, a derivative of pro-opiomelanocortin (POMC) at the hypothalamic MC4 receptor to increase food intake. Although leptin has been shown to regulate Agrp/Npy and Pomc-expressing neurones, there are differences with respect to Agrp regulation in leptin receptor-deficient mice and rats. Unlike the obese leptin receptor-deficient db/db mouse, which exhibits upregulation of Agrp mRNA expression in the medial basal hypothalamus (MBH) compared to lean controls, the obese leptin receptor-deficient (faf; Koletsky) rat does not exhibit upregulation of Agrp expression. To determine whether this represents a general difference between leptin receptor-deficient mice and rats, neuropeptide gene expression was analysed in the MBH of lean and obese rats segregating for a different leptin receptor mutation, Leprfa (Zucker). Fasting in lean rats (+/fa) for 72 h significantly increased Agrp and Npy mRNA expression, and decreased Pomc mRNA expression as detected by a sensitive solution hybridization/S1 nuclease protection assay. Npy mRNA levels were significantly increased in fed obese fa/fa compared to lean rats, and further increased in the obese animals after fasting. In contrast, Agrp mRNA levels did not differ between fed lean and fed obese rats, and fasting did not significantly change Agrp levels in obese rats. To determine whether the change in Agrp expression that occurs with food deprivation in lean rats could be prevented by leptin replacement, Sprague-Dawley rats were fasted and infused via subcutaneous osmotic micropumps for 48 h with either saline or recombinant mouse leptin. Fasting significantly increased Agrp and Npy, and decreased Pomc mRNA levels. Leptin infusion almost completely reversed these changes such that there was no significant difference between the levels in the fasted rats and those that were fed ad libitum. Thus, in fasted lean rats, Agrp and Npy are upregulated in parallel when leptin levels fall and are downregulated by leptin infusion. By contrast, the absence of a functional leptin receptor results in the upregulation of Npy but not Agrp mRNA.

Agouti-Related Protein↗

PubMed2001

[Conservative treatment of dislocated proximal humeral fractures].

Between 11/1989 and 6/1998 52 patients (10 m., 42 f., age median 72 years, 31-88) with proximal humeral fractures have been treated by conservative means (angulation of humeral head > 45 degrees and/or shaft displacement > 1 cm and displacement of greater tuberosity > 0.5 cm). In 37 patients (71%, 31 f., 6 m., age median 75 years, 36-88) a clinical and radiological follow-up could be obtained after median 20 months (3-93). According to the Neer-classification, subcapital 2-part fractures were found in 19 cases and 3-part fractures in 12 cases. 4-part fractures were diagnosed in 6 cases. By using the Constant-Score, the final result was scored "excellent" in 10 patients and "good" in 13 patients. In 7 patients each the results achieved were "moderate" or "poor". The underlying cause for the poor results was primarily due to persisting painful impairment in range of motion and loss of strength. Radiologically, persisting axial deviation was present in 23 cases, arthrosis in 14 patients and humeral head necrosis in 8 patients. Most commonly, poor functional and radiological results occurred in 4-part fractures. However, conservative therapy of displaced 2-part and 3-part fractures is a considerable therapeutical option since the final results are predominantly good. In contrast, due to the poor results after conservative therapy 4-part fractures should be treated surgically.

Adult↗

PubMed2000

Effects of leptin receptor mutation on Agrp gene expression in fed and fasted lean and obese (LA/N-faf) rats.

Agouti-related protein provides an orexigenic signal, probably through interaction with central melanocortin receptors. Expression of Agrp is markedly increased in the hypothalamus of mice deficient in leptin (Lep(ob)/Lep(ob)) or its receptor (Lepr(db)/Lepr(db)), suggesting that leptin mediates signals suppressing Agouti-related protein production. The regulation of Agrp expression in the rat hypothalamus has not been reported. We, therefore, analyzed the expression of Agrp in the medial basal hypothalamus of lean (+/+, +/fa(f)) and obese leptin receptor-deficient (fa(f)/fa(f)) LA/N rats. Using a sensitive solution hybridization/S1 nuclease protection assay, we found no significant difference in Agrp messenger RNA (mRNA) levels (pg/microg total RNA +/- SEM) in obese rats (n = 5), compared with lean controls (n = 5): 0.46 +/- 0.06 vs. 0.47 +/- 0.06 (P = 0.9). Similarly, no difference in Agrp expression was found using in situ hybridization or semiquantitative RT-PCR. In contrast to Agrp, Pomc mRNA levels were significantly suppressed in the obese, compared with the lean, rats (P = 0.001). Thus, the ratio of Pomc to Agrp mRNA is decreased in the obese rats and may be an important modulator of food intake. To assess the physiological regulation of Agrp in rats, we examined the effect of food deprivation in lean Sprague Dawley (SD) rats. There was a 273% increase in medial basal hypothalamus Agrp mRNA in SD rats fasted for 48 h (n = 8), compared with rats fed ad libitum (n = 8): 0.82 +/- 0.23 vs. 0.30 +/- 0.08 (P = 0.0001). Lean LA/N rats (n = 7) fasted for 48 h also showed a 231% increase in Agrp expression, compared with fed lean controls (n = 8): 0.74 +/- 0.11 vs. 0.32 +/- 0.03 (P = 0.002), whereas Pomc expression was decreased by 32% in fasted animals from the same experiment (0.34 +/- 0.05 vs. 0.50 +/- 0.07; P = 0.03). There were no significant differences in Agrp or Pomc mRNA levels between fasted and fed obese LA/N-fa(f) rats. These results suggest that, in the rat, the Agrp response to fasting may involve leptin-mediated phenomena, but factors in addition to leptin must also be involved in the regulation of Agrp gene expression.

Agouti-Related Protein↗

PubMed1999

[Bilateral posterior fracture-dislocation of the shoulder caused by an epileptic seizure - diagnostic, treatment and result].

The case of an 39-year-old man is presented, who sustained a bilateral locked fracture dislocation of the shoulders occurring during an epileptic seizure. Radiographs demonstrated a compression-fracture of the anteromedial aspect of the humeral head bilaterally (reversed Hill-Sachs-lesions). Additionally, fractures of the lesser and greater tuberosity were diagnosed at the right site. Open reduction and internal fixation was performed in both shoulders within 12 hours. 6 months later the patient has no complaints with a free range of motion. Diagnostics, treatment and result are discussed in context with the literature.

Adult↗

PubMed1999

Regulation of hypothalamic proopiomelanocortin by leptin in lean and obese rats.

The mechanisms by which leptin influences energy homeostasis are not entirely understood. Several observations indicate that proopiomelanocortin (POMC) is involved in the regulation of food intake and may be a mediator of leptin action. To further study this interaction, a sensitive solution hybridization assay was used to compare the levels of POMC mRNA in the medial basal hypothalamus (MBH) of lean (+/+, +/fa(f)) and obese leptin receptor-deficient (fa(f)/fa(f)) rats. POMC peptide products were also measured by RIA in the same animals. Cytoplasmic POMC RNA levels were significantly reduced by 53% in obese rats as compared with lean controls: 0.30 +/- 0.04 vs. 0.64 +/- 0.07 pg/microgram total RNA (p < 0.02). Significant reductions in mean concentrations of hypothalamic POMC-derived peptides from the same dissections were detected in the obese rats vs. lean controls: alpha-MSH 1.77 +/- 0.07 vs. 2.34 +/- 0.10; beta-EP 4.06 +/- 0.24 vs. 5.86 +/- 0.36; gamma(3)-MSH 5.32 +/- 0. 20 vs. 6.52 +/- 0.12 ng/mg protein (p < 0.001). To determine whether leptin stimulates POMC gene transcription, the acute effect of an intracerebroventricular (i.c.v.) injection of leptin (5 microgram) on POMC primary transcript was quantified in the MBH of lean rats after a 16-hour fast. There was a significant 167% increase in mean POMC hnRNA levels 3 h after i.c.v. leptin injection (1.15 +/- 0.22 pg/MBH; p < 0.02), but not after 1 h (0.76 +/- 0.08 pg/MBH), compared to saline controls (0.69 +/- 0.08 pg/MBH). 4 h after the injection of leptin, POMC hnRNA was still increased, but to a lesser extent (140%), as compared with control animals (p = 0.006). These studies demonstrate for the first time in the leptin receptor-deficient rat that there is an associated decrease in POMC gene expression and peptide levels in the MBH. Furthermore, the acute increase in the levels of POMC primary transcript in non-obese rats after a single i.c.v. injection of leptin supports a role for leptin in the regulation of POMC gene transcription. Taken together, these studies provide further evidence that POMC is an important mediator of the effects of leptin on food intake and energy expenditure.

Animals↗