Sustained release of locally delivered celecoxib provides pain relief for osteoarthritis: a proof of concept in dog patients

OBJECTIVE

Drug delivery platforms that allow for gradual drug release after intra-articular administration have become of much interest as a treatment strategy for osteoarthritis (OA). The aim of this study was to investigate the safety and efficacy of an intra-articular sustained release formulation containing celecoxib (CXB), a cyclooxygenase-2 (COX-2) selective inhibitor.

METHODS

Amino acid-based polyesteramide microspheres (PEAMs), a biodegradable and non-toxic platform, were loaded with CXB and employed in two in vivo models of arthritis: an acute inflammatory arthritis model in rats (n = 12), and a randomized controlled study in chronic OA dog patients (n = 30). In parallel, the bioactivity of sustained release of CXB was evaluated in monolayer cultures of primary dog chondrocytes under inflammatory conditions.

RESULTS

Sustained release of CXB did not alleviate acute arthritis signs in the rat arthritis model, based on pain measurements and synovitis severity. However, in OA dog patients, sustained release of CXB improved limb function as objective parameter of pain and quality of life based on gait analysis and owner questionnaires. It also decreased pain medication dependency over a 2-month period and caused no adverse effects. Prostaglandin E2 levels, a marker for inflammation, were lower in the synovial fluid of CXB-treated dog OA patients and in CXB-treated cultured dog chondrocytes.

CONCLUSION

These results show that local sustained release of CXB is less suitable to treat acute inflammation in arthritic joints, while safe and effective in treating pain in chronic OA in dogs.

Intra-articular injection of triamcinolone acetonide releasing biomaterial microspheres inhibits pain and inflammation in an acute arthritis model

Inflammation of the synovium and joint capsule is a main driver of pain in an osteoarthritic (OA) joint. Triamcinolone acetonide (TAA) is a classical corticosteroid that reduces synovitis and alleviates pain, albeit transiently. Biomaterial-based local TAA release may prolong the suppression of pain without the need for multiple injections. Polylactic-co-glycolic acid (PLGA) formulations of TAA prolong OA pain relief to a limited extent. A novel polyesteramide (PEA) microsphere platform allows for extended release in the OA joint for over 3 months. To evaluate their effect on pain and inflammation, TAA-loaded microspheres were intra-articularly delivered to the knee joint in a rat model of acute arthritis induced by intra-articular injection of streptococcal cell wall peptidoglycan-polysaccharide (PGPS) and subsequent flare-ups by intravenous PGPS injections. PEA-loaded microspheres were benchmarked with TAA-loaded PLGA microspheres and bolus TAA injection. TAA treatments were injected intra-articularly before the first induced flare-up. TAA-loaded PEA and PLGA microspheres reduced joint swelling and signs of pain-like behavior over the entire study period, as assessed by weight bearing and referred mechanical hypersensitivity, whereas bolus suspension was effective for a shorter time period. TAA-loaded PEA microspheres reduced lameness to a greater extent than TAA-loaded PLGA microspheres. In conclusion, a single intra-articular injection of TAA-loaded PEA microspheres reduced joint swelling and induced longer pain relief compared to bolus injection. Hence relief of inflammation and pain by PEA-based delivery of TAA may prove to be effective and durable.

Local controlled release of corticosteroids extends surgically induced joint instability by inhibiting tissue healing

Background and Purpose

Corticosteroids are intra‐articularly injected to relieve pain in joints with osteoarthritis (OA) or acute tissue damage such as ligament or tendon tears, despite its unverified contraindication in unstable joints. Biomaterial‐based sustained delivery may prolong reduction of inflammatory pain, while avoiding harmful peak drug concentrations.

Experimental Approach

The applicability of prolonged corticosteroid exposure was examined in a rat model of anterior cruciate ligament and medial meniscus transection (ACLT + pMMx) with ensuing degenerative changes.

Key Results

Intra‐articular injection of a bolus of the corticosteroid triamcinolone acetonide (TAA) resulted in enhanced joint instability in 50% of the joints, but neither instability‐induced OA cartilage degeneration, synovitis, nor the OA‐related bone phenotype was affected. However, biomaterial microsphere‐based extended TAA release enhanced instability in 94% of the animals and induced dystrophic calcification and exacerbation of cartilage degeneration. In healthy joints, injection with TAA releasing microspheres had no effect at all. In vitro, TAA inhibited cell migration out of joint tissue explants, suggesting inhibited tissue healing in vivo as mechanisms for enhanced instability and subsequent cartilage degeneration.

Conclusions and Implications

We conclude that short‐term TAA exposure has minor effects on surgically induced unstable joints, but its extended presence is detrimental by extending instability and associated joint degeneration through compromised healing. This supports a contraindication of prolonged corticosteroid exposure in tissue damage‐associated joint instability, but not of brief exposure.

Intra-articular injection of triamcinolone acetonide releasing biomaterial microspheres inhibits pain and inflammation in an acute arthritis model

Inflammation of the synovium and joint capsule is a main driver of pain in an osteoarthritic (OA) joint. Triamcinolone acetonide (TAA) is a classical corticosteroid that reduces synovitis and alleviates pain, albeit transiently. Biomaterial-based local TAA release may prolong the suppression of pain without the need for multiple injections. Polylactic-co-glycolic acid (PLGA) formulations of TAA prolong OA pain relief to a limited extent. A novel polyesteramide (PEA) microsphere platform allows for extended release in the OA joint for over 3 months. To evaluate their effect on pain and inflammation, TAA-loaded microspheres were intra-articularly delivered to the knee joint in a rat model of acute arthritis induced by intra-articular injection of streptococcal cell wall peptidoglycan-polysaccharide (PGPS) and subsequent flare-ups by intravenous PGPS injections. PEA-loaded microspheres were benchmarked with TAA-loaded PLGA microspheres and bolus TAA injection. TAA treatments were injected intra-articularly before the first induced flare-up. TAA-loaded PEA and PLGA microspheres reduced joint swelling and signs of pain-like behavior over the entire study period, as assessed by weight bearing and referred mechanical hypersensitivity, whereas bolus suspension was effective for a shorter time period. TAA-loaded PEA microspheres reduced lameness to a greater extent than TAA-loaded PLGA microspheres. In conclusion, a single intra-articular injection of TAA-loaded PEA microspheres reduced joint swelling and induced longer pain relief compared to bolus injection. Hence relief of inflammation and pain by PEA-based delivery of TAA may prove to be effective and durable.

Safety of intradiscal delivery of triamcinolone acetonide by a poly(esteramide) microsphere platform in a large animal model of intervertebral disc degeneration

BACKGROUND CONTEXT

Local corticosteroids have been used to relieve symptoms of chronic low back pain, although treatment effects have been shown to wear off relatively fast. Prolonging corticosteroid presence by controlled release from biomaterials may allow for longer pain relief while circumventing adverse effects such as high bolus dosages.

PURPOSE

The purpose of this study was to evaluate the safety and efficacy of intradiscal controlled release of triamcinolone acetonide (TAA) by poly(esteramide) microspheres in a canine degenerated intervertebral disc (IVD) model.

STUDY DESIGN

In a preclinical experimental large animal model, the effect of prolonged glucocorticoid exposure on disc degeneration was evaluated.

METHODS

Degeneration was accelerated by nucleotomy of lumbar IVDs of Beagle dogs. After 4 weeks, microspheres loaded with 8.4 µg TAA, and 0.84mg TAA were administered to the degenerated IVDs by intradiscal injection (n=6 per group). Empty microspheres (n=6) and all adjacent non-nucleotomized noninjected IVDs were included as controls (n=24). Immediately prior to TAA administration and after 12 weeks, magnetic resonance imaging was performed. Degenerative changes were evaluated by disc height index, Pfirrmann grading, T1ρ and T2 mapping values, postmortem CT scans, macroscopic and microscopic grading, and biochemical/immunohistochemical analysis of inflammation and extracellular matrix content. In addition, nerve growth factor (NGF) protein expression, a biomarker for pain, was scored in nucleus pulposus (NP) tissues. The study was funded by a research grant from Health Holland (1.3million euros = 1.5million US dollars).

RESULTS

Macroscopic evaluation and CT images postmortem were consistent with mild disc degeneration. Other abnormalities were not observed. Nucleotomy-induced degeneration and inflammation was mild, reflected by moderate Pfirrmann grades and PGE₂ levels. Regardless of TAA dosage, local sustained delivery did not affect disc height index nor Pfirrmann grading, T1ρ and T2 mapping values, PGE₂ tissue levels, collagen, GAG, and DNA content. However, the low dosage of TAA microspheres significantly reduced NGF immunopositivity in degenerated NP tissue.

CONCLUSIONS

This is the first in vivo application in a preclinical large animal model of a controlled release formulation of corticosteroids in mild IVD degeneration. Sustained release of TAA locally in the IVD appeared safe and reduced NGF expression, suggesting its potential applicability for pain relief, although beneficial effects were absent on tissue degeneration.

CLINICAL SIGNIFICANCE

The present platform seems to be promising in extending the local controlled delivery of TAA with the potency to provide long-standing analgesia in the subset of LBP patients suffering from discogenic pain.

Prolonged inhibition of inflammation in osteoarthritis by triamcinolone acetonide released from a polyester amide microsphere platform

Controlled biomaterial-based corticosteroid release might circumvent multiple injections and the accompanying risks, such as hormone imbalance and muscle weakness, in osteoarthritic (OA) patients. For this purpose, microspheres were prepared from an amino acid-based polyester amide (PEA) platform and loaded with triamcinolone acetonide (TAA). TAA loaded microspheres were shown to release TAA for over 60days in PBS. Furthermore, the bioactivity lasted at least 28days, demonstrated by a 80-95% inhibition of PGE₂ production using TNFα-stimulated chondrocyte culture, indicating inhibition of inflammation. Microspheres loaded with the near infrared marker NIR780-iodide injected in healthy rat joints or joints with mild collagenase-induced OA showed retention of the microspheres up till 70days after injection. After intra-articular injection of TAA-loaded microspheres, TAA was detectable in the serum until day seven. Synovial inflammation was significantly lower in OA joints injected with TAA-loaded microspheres based on histological Krenn scores. Injection of TAA-loaded nor empty microspheres had no effect on cartilage integrity as determined by Mankin scoring. In conclusion, the PEA platform shows safety and efficacy upon intra-articular injection, and its extended degradation and release profiles compared to the currently used PLGA platforms may render it a good alternative. Even though further in vivo studies may need to address dosing and readout parameters such as pain, no effect on cartilage pathology was found and inflammation was effectively lowered in OA joints.

Marker-free motion correction in weight-bearing cone-beam CT of the knee joint

PURPOSE

To allow for a purely image-based motion estimation and compensation in weight-bearing cone-beam computed tomography of the knee joint.

METHODS

Weight-bearing imaging of the knee joint in a standing position poses additional requirements for the image reconstruction algorithm. In contrast to supine scans, patient motion needs to be estimated and compensated. The authors propose a method that is based on 2D/3D registration of left and right femur and tibia segmented from a prior, motion-free reconstruction acquired in supine position. Each segmented bone is first roughly aligned to the motion-corrupted reconstruction of a scan in standing or squatting position. Subsequently, a rigid 2D/3D registration is performed for each bone to each of K projection images, estimating 6 × 4 × K motion parameters. The motion of individual bones is combined into global motion fields using thin-plate-spline extrapolation. These can be incorporated into a motion-compensated reconstruction in the backprojection step. The authors performed visual and quantitative comparisons between a state-of-the-art marker-based (MB) method and two variants of the proposed method using gradient correlation (GC) and normalized gradient information (NGI) as similarity measure for the 2D/3D registration.

RESULTS

The authors evaluated their method on four acquisitions under different squatting positions of the same patient. All methods showed substantial improvement in image quality compared to the uncorrected reconstructions. Compared to NGI and MB, the GC method showed increased streaking artifacts due to misregistrations in lateral projection images. NGI and MB showed comparable image quality at the bone regions. Because the markers are attached to the skin, the MB method performed better at the surface of the legs where the authors observed slight streaking of the NGI and GC methods. For a quantitative evaluation, the authors computed the universal quality index (UQI) for all bone regions with respect to the motion-free reconstruction. The authors quantitative evaluation over regions around the bones yielded a mean UQI of 18.4 for no correction, 53.3 and 56.1 for the proposed method using GC and NGI, respectively, and 53.7 for the MB reference approach. In contrast to the authors registration-based corrections, the MB reference method caused slight nonrigid deformations at bone outlines when compared to a motion-free reference scan.

CONCLUSIONS

The authors showed that their method based on the NGI similarity measure yields reconstruction quality close to the MB reference method. In contrast to the MB method, the proposed method does not require any preparation prior to the examination which will improve the clinical workflow and patient comfort. Further, the authors found that the MB method causes small, nonrigid deformations at the bone outline which indicates that markers may not accurately reflect the internal motion close to the knee joint. Therefore, the authors believe that the proposed method is a promising alternative to MB motion management.

Celecoxib-loaded PEA microspheres as an auto regulatory drug-delivery system after intra-articular injection

In this study, we investigated the potential of celecoxib-loaded polyester amide (PEA) microspheres as an auto-regulating drug delivery system for the treatment of pain associated with knee osteoarthritis (OA). Celecoxib release from PEA microspheres and inflammation responsive release of a small molecule from PEA was investigated in vitro. Inflammation responsive release of a small molecule from PEA was observed when PEA was exposed to cell lysates obtained from a neutrophil-like Hl-60 cell line. Following a short initial burst release of ~15% of the total drug load in the first days, celecoxib was slowly released throughout a period of >80days. To investigate biocompatibility and degradation behavior in vivo, celecoxib-loaded PEA microspheres were injected in OA-induced (ACLT+pMMx) or contralateral healthy knee joints of male Lewis rats. Bioactivity of celecoxib from loaded PEA microspheres was confirmed by PGE₂ measurements in total rat knee homogenates. Intra-articular biocompatibility was demonstrated histologically, where no cartilage damage or synovial thickening and necrosis were observed after intra-articular injections with PEA microspheres. Degradation of PEA microspheres was significantly higher in OA induced knees compared to contralateral healthy knee joints, while loading the PEA microspheres with celecoxib significantly inhibited degradation, indicating a drug delivery system with auto regulatory behavior. In conclusion, this study suggests the potential of celecoxib-loaded PEA microspheres to be used as a safe drug delivery system with auto regulatory behavior for treatment of pain associated with OA of the knee.

Zum photochemischen Verhalten einiger N-Alkylacridinium-Kationen und N, N′-Dialkyl-9.9-′-diacridane in äthanolischer Lösung II

Die N-Methyl-, N-Äthyl-, N-n-Propyl- und N-n-Butylacridiniumjodide werden synthetisiert und diese mit AgNO3 in äthanolischer Lösung in die entsprechenden Nitrate umgewandelt. Lösungen der Konzentrationen 2-3 · 10-2-m. in O2-freiem Äthanol werden in Pyrex- oder Quarzgefäßen mit Osram HBO 200- oder Hanau TQ 81-Lampen der Photolyse unterworfen.

Die N-Alkylacridiniumsalze werden dabei im Primärakt unter Übertragung eines H-Atoms vom Lösungsmittel photoreduziert. Dabei bildet sich sehr wahrscheinlich ein N-Alkylacridaniumradikal-Kation. Dieses gibt ein Proton ab, das quantitativ nachgewiesen wird; es bildet sich ein N-Alkylacridanylradikal, das mit sich selbst zu den entsprechenden N,N′-Dialkyl-9.9′-diacridanen dimerisiert. Diese Diacridane sind relativ schwer löslich und fallen bei der Photolyse als Festsubstanzen aus. Das N,N′-Diäthyldiacridan hat im Entstehungszustand die größte Löslichkeit; sie beträgt 4,4 · 10-3-m. bei 30°. Zum N,N′-Dimethyl- bzw. N,N′-Di-n-Propyl- und N,N′-Di-n-Butyldiacridan fällt die Löslichkeit rasch ab und bedingt, daß auch bei höheren Reaktionstemperaturen Umsätze von 80 - 100% vor Einsetzen einer merklichen Rückbildungsreaktion erzielt werden können.

Die N,N′-Dialkyldiacridane sind selbst photochemisch instabil. Sie zerfallen im Primärprozeß heterolytisch in ein N-Alkylacridinium-Kation und ein entsprechendes Anion, das sich rasch, vermutlich zu einem Acridan stabilisiert. Diese photolytische Instabilität der N,N′-Dialkyldiacridane bedingt bei höheren Reaktionstemperaturen und größerer Löslichkeit, daß beim N,N-Diäthyldiacridan die Rückreaktion schon bei einem 40-proz. Umsatz in den Vordergrund kommt und kein festes Diacridan gebildet wird.

Transarterial chemoembolization (TACE) for inoperable intrahepatic cholangiocarcinoma

The aim of this retrospective study was to determine the safety and efficacy of chemoembolization (TACE) as palliative treatment for patients with unresectable intrahepatic cholangiocarcinoma (CCA) and to compare the results with those in the literature. Fifteen patients with histology-proven CCA (5 men, 10 women) had received palliative treatment with TACE over a 6-year period. The treatment protocol comprised repeated TACE at a minimum of 8-week intervals. TACE was performed with a mixture of 10 ml Lipiodol and 10 mg mitomycin C injected into the tumor-supplying vessels. Follow-up investigations after 8-10 weeks comprised contrast-enhanced multislice spiral CT and laboratory control. Statistical evaluation included survival analysis using the Kaplan-Meier method. During the investigation period 58 TACEs (3.9 +/- 3.8; 1-15) were performed in 15 patients. Mean tumor size was 10.8 +/- 4.6 cm (range, 2.0-18.0 cm). Unifocal tumor disease was diagnosed in eight patients, and multifocal disease in seven. Mean survival was 21.1 months (95% CI, 9.4-32.5 months). At the end of the investigation period 3 patients are still alive, and 12 patients have died. The 1-, 2-, and 3-year survival rate was 51.3%, 27.5%, and 27.5% respectively. According to RECIST criteria interim best response to therapy was stable disease in 9 of 15 patients, a partial response in 1 of 15 patients, and tumor progression in 4 of 15 patients. No deaths and no acute liver failure occurred under TACE therapy. Major complications were observed in two patients, comprising anaphylactic shock owing to contrast medium administration in one and gastric ulceration due to lipiodol displacement in the second patient. These results demonstrate that TACE is a safe procedure with a moderate number of complications for patients suffering from inoperable CCA. According to recently published data on i.v. chemotherapy we suggest that TACE might be able to prolong survival in selected patients who would succumb under other palliative treatment modalities.

[Hilar cholangiocarcinoma -- results of en bloc resection of tumor and liver]

The increasingly performed en bloc resection of liver and hilar tumor has contributed to the improvement of long-term survival in patients with hilar cholangiocarcinoma. Based on preoperative definition of operative strategy we tried to avoid any traumatization of the hilar region. Between September 1997 and September 2002, 82 patients with hilar cholangiocarcinoma were treated at our department. Three patients were excluded from any surgery. The resection rate was 75% (59 of 79); 79% (38 of 48) of en bloc resections of the hilar tumor and adjacent liver were formally curative. The hospital mortality was 7%. The 1- and 3-year survival rates of patients after explorative laparotomy, palliative and curative resection was 27 and 7%, 67 and 26%, 89 and 45% ( p<0.001), respectively. The 1- and 3-year survival rates of patients after en bloc resection were 78 and 49%, respectively. In patients with formally curative en bloc resection ( n=38), the 3-year survival rate was 63%; in patients with N0/R0 resection ( n=31) it was 71%. Lymph node involvement proved to be the only independent prognostic marker if patients who underwent hilar and en bloc resection were included in the multivariate analysis. The R situation was the only significant predictor for patients after en bloc resection. These data justify the extended diagnostic work-up and the principal liver resection in hilar cholangiocarcinoma.

Prolonged rat allograft survival induced by temporary elimination of alpha/beta T cells with monoclonal antibody

We tested the ability of lewis (LEW; RT-1(1)) recipients to reject DA (RT-1av1) cardiac allografts following the selective elimination of alpha/beta T cells with the mouse monoclonal antibody R73. One group of adult rats (6 weeks old) received 1000 microg R73 i.p. on days 2 and 1 before transplantation, and 100 microg R73 every third day after transplantation up to day 18. Prolonged cardiac graft survival was noted (30, 30, 32, 51, 62, 108, > 500, > 500, > 500 days). Untreated controls (n = 10) rejected their grafts within 7 +/- 1 days. R73 therapy induced a dramatic decrease in alpha/beta T cells from 69% before treatment to 5% within the first 5 days, followed by an increase to 64% by day 8. The T cell increase was paralleled by the appearance of anti-mouse antibody. A second group of adult rats (10 weeks old) received the same treatment. These "older" recipients rejected their grafts within 20 +/- 5 days. Chronic R73 therapy from birth until the day of transplantation (100 microg R73 i.p. twice a week) resulted in graft survival of 37 +/- 9 days in eight animals. Two rats had a graft survival of more than 200 days. When chronic R73 therapy was continued to day 70 after transplantation, DA hearts were accepted well in all animals for more than 100 days. Alpha/beta T cells were virtually absent throughout the whole time of treatment. Antibodies against R73 were not detected. We concluded that selective elimination of alpha/beta T cells has a strong effect on allograft survival.

Heart allograft survival in rats following immunization with soluble peptide MHC class I donor antigens: evidence for the role of indirect recognition in rejection

The current series of experiments addressed the question of whether indirect priming with donor MHC antigens affects heart allograft survival. LEW (RT-1(1)) rats were immunized with a mixture of two peptides corresponding to the variable region of MHC class I locus Aa antigen (alpha1 and alpha2 domain). The recipients were transplanted with a DA (RT1-1a) heart 1 month after immunization, and graft survival was closely monitored by ECG. All peptide-treated recipients presented with anti-peptide antibodies at the time of transplantation and developed a strongly accelerated graft rejection. These findings indicated that indirect recognition of MHC I donor antigens promotes heart allograft rejection.

Characterization and reduction of ischemia/reperfusion injury after experimental pancreas transplantation

Reperfusion injury after pancreas transplantation is a cause of early graft pancreatitis. The aim of this study was to quantify pancreatic microcirculation after pancreas transplantation in correlation with cold ischemia time. In a second step the effect of N-acetylcysteine on reperfusion damage was tested. Pancreas transplantation was performed in three different groups of male Lewis rats. Groups 1 and 2 received no special treatment. Cold ischemia time was 1.5 hours in group 1 and 16 hours in groups 2 and 3. In group 3 donor and recipient were both treated with N-acetylcysteine (300 mg/kg) 1.5 hours after reperfusion graft microcirculation was quantified by means of intravital microscopy. Rhodamine-labeled leukocytes, fluoroscein isothiocyanate-labeled erythrocytes, and fluoroscein isothiocyanate-albumin were used as fluorochromes. After a cold ischemia time of 16 hours, functional capillary density, erythrocyte velocity, and leukocyte-endothelium interaction were reduced significantly compared to a cold ischemia time of 1.5 hours (P<0.05). After 16 hours of cold ischemia, treatment with N-acetylcysteine improved all of these parameters (P</=0.05). Ischemia/reperfusion injury after experimental pancreas transplantation is characterized by a disturbance of the pancreatic microcirculation exhibiting a correlation with the duration of cold ischemia. Treatment of donor and recipient with N-acetylcysteine resulted in prevention of cold ischemia-induced microcirculatory disturbance.

[Basic documentation: inpatient management in a region by a psychiatric hospital and a psychiatric department. Results of a joint evaluation]

A mental hospital and a psychiatric department of a general hospital in the region of Kassel have jointly analysed their basic documentation to produce an overview of hospital treatment of psychiatric patients in the region. Patients from the urban population occupy twice as many beds as those from the rural population which is a hint that standard bed-ratios per population are inadequate. Instead of the unsuitable official definition of duration of stay in hospital we used "days in hospital per person per year". Making allowance for groups of diagnoses this made possible interesting comparisons about the contributions of the two hospitals to the treatment of the psychiatric patients in the region. The two hospitals are not similar and the results show how the patients make use of the possibility of choosing the various specialities of the two hospitals.

[Decreasing reperfusion damage with N-acetylcysteine in experimental pancreas transplantion]

In this study we investigated the effect of donor and recipient conditioning with N-acetylcysteine on the ischemia/reperfusion injury after experimental pancreas-transplantation. We performed standardized pancreaticoduodenal transplantation in male lewis rats. The pancreas was perfused with UW-solution, harvested and conserved at 4 degrees C. Cold ischemia time was 1.5 hours and 16 hours respectively. The microcirculation in the transplanted organ was quantified by means of intravital microscopy 1.5 hours after implantation and reperfusion in the recipient. After 16 hours of cold ischemia we found a significant reduction in capillary erythrocyte velocity and a significantly enhanced leucocyte/endothelium interaction. The treatment with N-acetylcysteine resulted in a significant improvement of these microcirculatory disorders after prolonged cold ischemia.

Size controlled production of biodegradable microparticles with supercritical gases

Polymer microparticles were produced by means of the aerosol solvent extraction system. A solution of 3% w/w poly(L-lactic acid) in dichloromethane was sprayed into supercritical or near critical carbon dioxide gas phase. The mean particle size by volume moderately depended on the nozzle diameter and the spraying pressure used. When the polymer solution was saturated with carbon dioxide up to 5.0 MPa, the particle size and morphology of the particles were unchanged and the product was less agglomerated. Microparticles with mean diameters from 6 to 50 microns were achieved by decreasing the carbon dioxide density from 690 to 250 kg/m3. The surface structure of the particles sprayed in low density carbon dioxide showed cracks and holes. All other particles were non-porous with a smooth surface.

[Indications, technical implementation and results of endobronchial stent implantation]

14 patients with central malignant airway obstructions (n = 10), poststenotic pneumonia (n = 2) and esophagotracheal fistulas (n = 2) were treated with self-expanding stents in the trachea (n = 9), right (n = 4) and left (n = 1) main bronchus. The results showed that stent implantation in the tracheobronchial system is a very effective palliative treatment in the above-mentioned indications which takes immediate effect and complements the already established palliative therapy modalities in central airway malignancies.

Thoracoscopic resection of parenchymal blebs in spontaneous pneumothorax. Indications, operative management and results

The success rate of thoracoscopic resection of parenchymal blebs in spontaneous pneumothorax was evaluated after 54 thoracoscopies (cases) in 52 patients. Switch to open thoracotomy was necessitated by interpleural adhesions or large bullae in five cases, while 49 were treated thoracoscopically. The median duration of the operation was 75 (25-240) min, and the postoperative hospital stay was 7 (3-25) days. Early postoperative complications were haemothorax and recurrence of pneumothorax, each in one case, treated with thoracoscopy and chest drain, respectively. Forty-six patients were followed up for a median of 11 (1-32) months. there were two recurrences (at 4 and 6 months). One was successfully treated with thoracoscopy and the other with thoracotomy. Only five patients complained of slight sensitivity in the scar area, caused by weather changes. Thoracoscopic bleb resection is an effective alternative to thoracotomy, with low rates of complications and recurrent pneumothorax.

Short-term T cell receptor directed immunotherapy induces organ specific peripheral tolerance in a strongly incompatible rat model

We analysed the effect of selective alpha/beta-T cell elimination on allograft survival in a strongly histoincompatible DA-->LEWIS rat model by treatment of recipients with the mouse monoclonal antibody R73 two times before and seven times after transplantation. R73 induced virtually indefinite cardiac allograft survival in 44% of six-week-old LEWIS recipients, whereas donor-type skin allografts were rejected within 11 days. The remaining 56% of animals presented a mean cardiac survival time of 41 +/- 13 days. Graft prolongation was age dependent since in ten-week-old animals the survival time was only of 19 +/- 5 days (untreated controls: 7 +/- 1 days). R73 induced a rapid decrease of R73-positive T cells in the peripheral blood from 70% before treatment to 2%. From the fifth day of treatment a gradual T cell recovery was registered. The T cell marker CD5 decreased from 72% to 17% but recovered already from the second day of treatment. Determination of alpha/beta-TCR, CD3 and CD5 density on T cells during R73 therapy showed that the initial T cell decrease was due to T cell elimination, whereas modulation of alpha/beta-TCR was predominant during the following days. Anti-R73 antibodies appeared regularly during the first week of treatment and blocked R73 activity, indicating their anti-idiotypic nature. The present findings show that short-term R73 therapy is able to induce long-lasting allograft survival. This experimental model can be used to study the basis of peripheral organ specific T cell tolerance.

Deficiency of cartilage in the segmental bronchi of a child: congenital or acquired?

The case of a 4-year-old girl suffering from a severe bronchopneumonia of the left lower lobe is presented. Microscopically no cartilage was found in the resected lobe distal to the lobar bronchus. The case is unusual because a congenital lobar emphysema associated with an aplasia of bronchial cartilage has to be considered as well as secondary cartilage destruction due to chronic relapsing inflammations.

Long-term follow-up of different therapy procedures in spontaneous pneumothorax

The objective of this follow-up study was to evaluate the success rate of different therapy procedures in spontaneous pneumothorax. In order to achieve comparable conditions the study was restricted to those patients who were treated because of a first episode (n = 96) in the time between January 1978 and December 1987. Seventy-one were males and 25 females, ratio 3:1. The right side to left side ratio was 3:2. Both sides were affected in 11% (n = 11). All patients received an intercostal tube drainage with a permanent suction. In case of treatment failure thoracoscopy, pleurodesis or an operation were performed. The follow-up investigations was performed in January 1990 thus to further evaluate the outcome of 79 patients (82%) after 2 to 12 years after treatment. Among the patients, 33 patients presented a persistence or an early recurrence, 26 of them were operated during their first stay in hospital. A further 25 patients presented a late recurrence, of whom 14 underwent a later thoracotomy. Consequently the drainage therapy had a failure rate of 61% (n = 58). The frequency of operation was 42% (n = 40). The results after thoracotomy (n = 26) were as follows: slight complications, which did not require surgical treatment occurred in 8% (n = 2). The long-term results after surgical intervention (lung apex resection and/or parietal pleurectomy) were excellent concerning the rate of late recurrences (0% within the follow-up group) and the general condition (96% free or almost free of symptoms) regardless the method of operation.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatic reperfusion injury following orthotopic liver transplantation in the rat

At 24 hr following orthotopic transplantation, rat liver grafts were perfused in situ for 7 min with trypan blue, a vital dye that provides information on hepatic microcirculation and stains nuclei of nonviable cells. Spotty and uneven dye distribution was observed indicating that hepatic microcirculation was disturbed 24 hr following transplantation surgery. Under these conditions, 15-20% of the hepatocytes were nonviable as assessed from trypan blue staining and frank necrosis. In contrast, perfusion of livers from untransplanted rats or liver explants exposed to cold ischemia for 60 min were judged normal by the criteria of uniform distribution of dye in the organ and absence of necrosis and nuclear dye uptake. Thus the observed damage was associated with reintroduction of blood and can therefore be classified as a reperfusion injury. The altered microcirculation and cell death following the operation was reduced markedly by perfusion of the cold, ischemic explant with nitrogen-saturated but not with oxygen-saturated buffer for 5 min prior to the implantation operation. Protection was even greater if the perfusion medium contained verapamil (20 micrograms/ml), a Ca++ channel blocker. We conclude that reperfusion of the stored liver causes an oxygen-dependent alteration in hepatic microcirculation that leads to hypoxia and scattered hepatocellular necrosis in the implanted graft. Brief perfusion of the hypoxic implant under anaerobic conditions may remove substrates involved in oxygen radical generation and prevent reperfusion injury upon introduction of oxygen into the graft via the blood. Taken together, these results suggest that removal of Euro-Collins' solution under anaerobic conditions may be beneficial clinically in preventing injury of surgical explants.

The influence of (+/-)-15-deoxyspergualin on experimental transplantation and its immunopharmacological mode of action

15-Deoxyspergualin, a novel structure which was described to have anti-tumor activity, was tested on its influence on the survival time of transplanted organs. Prolongation of graft survival was demonstrated in rat skin (LEW----Fischer), islet cells heart and kidney transplantation (DA----LEW) as well as in allogeneic tumor transplantation in mice (C57Bl/6----Balb/c). Especially in the kidney transplantation a long-lasting transplant survival time was observed, indicating induction of tolerance. Examination of its immunopharmacological properties showed that the mononuclear phagocytes and not the lymphocytes are primarily affected by the substance, thus expressing a new mode of action for a substance being effective in transplantation immunology.

[Tasks of the psychiatric polyclinic]

Results of a random sample investigation at the psychiatric out-patient department of the University of Göttingen are reported: Data derived from 1479 consultations of 757 patients are given (age, sex, diagnosis, way of referral, advice for further treatment) and compared to those attending other in-patient and out-patient services and practitioners. We discuss the achievements of an out-patient department, also considering, however, that patients suffering from schizophrenia, alcoholism and psychogeriatric illness are only insufficiently taken care of, thus wanting further means of attendance to be offered.