Abstract 1260: Tumor hypoxia conditions glioblastoma cells for immunosuppression

Glioblastoma (GBM) is the most common and lethal malignant brain tumor that invariably recurs after standard therapy, with a median survival of only ~16 months. A major determinant of high GBM lethality is the overall immunosuppressive tumor microenvironment and the presence of treatment resistant hypoxic niches. In a recent study, we engineered murine GBM cell line GL261 with a lentiviral HRE driven fluorescent reporter, HRE-UnaG-PEST to study the relationship between tumor hypoxia and immunosuppression. By 3-4 weeks post-transplant in mice, we observed an abundance of UnaG+ GBM cells that were organized as pseudopalisading patterns around necrotic cores, similar to histological features observed in GBM patient specimens. We also observed an accumulation of TAMs and cytotoxic T cells inside hypoxic cores surrounded by UnaG+ GBM cells, which coincided with a gradual increase in vascular disarray and development of hypoxic niches. Single cell RNA sequencing (scRNA-seq) revealed that UnaG+ GBM cells were negatively enriched for neuroinflammation, Type II IFN signaling, TNFα and NF-κB signaling pathways, and IFNα and IFNγ responses. Furthermore, the gene ontology term “Negative Regulation of Immune System Process” (including genes such as Mif, Lgals3, Sdc4, Cd44, Dusp1) was predominantly upregulated in UnaG+ GBM cells. Hypoxia transcriptional program in GL261 GBM thus favors immunosuppression. To longitudinally study the immunosuppressive transcriptional programs of hypoxic GBM cells, we combined lentiviral HRE-CreERT2 with a knock-in of CAG-loxP-STOP-loxP-tdTomato (LSL-tdTom) reporter into the Rosa26 locus as a lineage tracing reporter for hypoxia-exposed GBM cells. A subclone of GL261-HRE-CreERT2; LSL-tdTom cells that displayed low baseline expression and faithful induction of tdTomato upon exposure to 1% O2 and 4-hydroxytamoxifen was identified and intracranially transplanted in mice. After a single tamoxifen injection day 21 post-transplant, mice were traced for 2 days or 7 days before analysis. At both timepoints, we observed abundant tdTom+ GBM cells spread throughout the tumor. Few tdTom+ GBM cells showed GLUT1 expression, more so in 7-day tracing than 2-day tracing. Hence, as the tumor progressed, most tdTom+ GL261 cells no longer experienced hypoxia, likely due to new angiogenesis or migration away from hypoxic areas. No tdTom+ GL261 cells were observed in parallel control experiments where tamoxifen was not injected. To investigate if hypoxia-induced immunosuppressive adaptations are preserved along tumor progression, further scRNA-seq and FACS studies will be performed to characterize the transcriptional profile of tdTom+ GBM cells. To test if hypoxic exposure is a critical conditioning event that promotes an immunosuppressive environment in GBM, we plan to genetically eliminate hypoxic GBM cells by inducing expression of Diptheria Toxin and evaluate effect on functional state of immune cells.

Citation Format: Anirudh Sattiraju, Sangjo Kang, Hongyan Zou, Roland Friedel. Tumor hypoxia conditions glioblastoma cells for immunosuppression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1260.

TAMI-59. RECIPROCAL IMPACT OF CANCER IMMUNITY AND TUMOR HYPOXIA DURING GLIOBLASTOMA PROGRESSION

Tumor hypoxia is linked to poor outcome for glioblastoma (GBM), a highly malignant brain cancer, but the underlying mechanisms and the environmental factors that initiate tumor hypoxia are poorly understood. We tracked tumor hypoxia in GBM in immunocompetent mice with a hypoxia sensitive fluorescent reporter combined with single cell transcriptomics. We found that hypoxic GBM cells are quiescent, immunosuppressive and display a mesenchymal transition, all of which are linked to malignant potency. We also captured in vivo hypoxia gene signature, which is more represented in recurrent GBM and predicts worse outcome. Interestingly, hypoxic GBM cells is a diverse population, consisted of four subclusters, and enriched for immune pathways. Concordantly, our reporter highlighted a distinct geographic pattern of immune cells in hypoxic regions, with phagocytic tumor-associated macrophages (TAMs) and CD8+ cytotoxic T cells (CTLs) congregated in hypoxic cores confined by hypoxic GBM cells in pseudo-palisading patterns. Mechanistically, this is a dynamic temporospatial process, requiring cytokine CCL8. Remarkably, the sequestered TAMs also experience hypoxia, and they are reprogrammed to express immunotolerant markers by factors released from hypoxic GBM cells. Contrary to the conventional viewpoint that hypoxia arises from rapid tumor expansion outstripping vascular supply, we discovered anticancer immunity as an important driving force of tumor hypoxia; attenuating immune responses by implanting GBM in host mice with immunodeficiency or IL1β deletion greatly decreased GBM hypoxia. Analyses of human patient GBM samples highlighted a connection of mesenchymal subtype, immune response, and tumor hypoxia, all contributing to poor survival. Altogether, our study revealed a reciprocal influence of anti-tumor immunity and tumor hypoxia, which has significant ramifications for prognosis and immunotherapy for GBM.

TAMI-60. MODULATION OF CELL BIOMECHANICS THROUGH GUIDANCE RECEPTOR PLEXIN-B2 FACILITATES GLIOBLASTOMA INFILTRATION

Infiltrative growth is a major cause of the high lethality of malignant brain tumors such as glioblastoma (GBM). The study of the contribution of biomechanical processes to GBM invasion is an emerging field. We show here that GBM cells upregulate the guidance receptor Plexin-B2 to gain invasiveness by modulating their biomechanical properties. Deletion of Plexin-B2 in GBM stem cells limited tumor spread and shifted invasion paths from axon fiber tracts to perivascular routes. On a cellular level, Plexin-B2 adjusts cell adhesiveness, migratory responses to different matrix stiffness, and actomyosin dynamics, thus empowering GBM cells to leave stiff tumor bulk and infiltrate softer brain parenchyma. Correspondingly, gene signatures affected by Plexin-B2 were associated with locomotor regulation, matrix interactions, and cellular biomechanics. On a molecular level, the intracellular Ras-GAP domain contributed to Plexin-B2 function, while the signaling relationship with downstream effectors Rap1/2 appeared variable between GBM stem cell lines, reflecting intertumoral heterogeneity. Our studies have established Plexin-B2 as a modulator of cell biomechanics that is usurped by GBM cells to gain invasiveness. Ongoing investigations focus on the regulation of the biomechanical properties of cell membrane and cell actomyosin cortex through plexins that provide GBM cells with the mechanical dynamics to penetrate to restricted space.

TAMI-61. EXAMINING THE ROLE OF HYPOXIA INDUCED GENES CXCR4 AND NXPH4 IN INVASION OF HYPOXIC GLIOBLASTOMA CELLS

Hypoxia (low oxygen) has been associated with adverse effects in tumor biology by exaggerating the capabilities of invasion, proliferation, and survival of tumor cells within the tumor microenvironment. We engineered glioblastoma (GBM) proneural cells with a novel hypoxia reporter, HRE-UnaG, to study areas of tumor hypoxia and the effects that these hypoxic cells have on tumorigenesis. Single cell RNA-seq analysis from a mouse intracranially injected with our HRE dUnaG GBM cells revealed a shift to a mesenchymal state upon hypoxia (detected by expression of UnaG). Two genes, CXCR4 and NXPH4, were identified as being specifically induced in the hypoxic population. Our studies focus on the hypothesis that these two hypoxia induced genes, CXCR4 and NXPH4, are upregulated in hypoxic GBM cells, which may allow tumor cells to become more aggressive and resistant to conventional forms of therapies. GBM cells will be transduced with lentiviral vectors for Dox inducible shRNA knockdown of CXCR4 or NXPH4 to test specific contribution of these genes to the phenotype of the hypoxic population, with particular focus on the change in invasion and overall tumor burden upon gene silencing.

TAMI-21. TUMOR-ASSOCIATED MICROGLIA GUIDE GBM INFILTRATION VIA PLEXIN-B2

Glioblastoma (GBM) is the most common malignant primary brain tumor. The nature of invasiveness of GBM makes complete surgical resection difficult. However, how GBM cells achieve wide infiltration in the brain is poorly understood. Microglia, the resident immune cells in the brain can support GBM growth and invasion, but the underlying mechanisms remain elusive. Here, we show that microglia are activated in a wide field away from tumor boundaries, ahead of tumor cell infiltration. Invading GBM cells are in close contact with microglia, progressively aligned with one another in the direction of tumor invasion. Moreover, ECM is also aligned with the infiltrating tumor and microglia, which may serve as invasion tracks in the brain. Mechanistically, we demonstrate that microglia direct cellular alignment and ECM remodeling in the invasion tracks through an axon guidance receptor Plexin-B2. Myeloid-specific ablation of Plexin-B2 perturbs microglia and tumor cell alignment, microglia migration, ECM organization, and GBM invasiveness. Together, our data reveal a hitherto under-appreciated role of microglia in providing directional cues for GBM invasion through physical interaction and alignment of ECM and tumor cells, thus providing new insights and novel molecular targets in curbing GBM invasion.

ANGI-13. PLEXIN-B2 FACILITATES DIFFUSE GLIOMA INVASION BY REGULATING CELL ADHESION AND ACTO-MYOSIN DYNAMICS

Diffuse invasion of glioblastoma (GBM) cells into brain tissue is a key factor for its high lethality. GBM cell migration is affected by functions of plexins, which are transmembrane receptors of semaphorins that regulate cell adhesion and cytoskeletal dynamics. Expression of Plexin-B2 is upregulated in GBM and correlates with malignancy. We show here that Plexin-B2 activity regulates biomechanical properties of GBM cells, promoting invasive growth. Plexin-B2 activity increased the capacity of GBM to invade as dispersed single cells by reducing the cell-cell adhesiveness between GBM cells, indicating that a major function of Plexin-B2 activity is to downregulate cell-cell adhesion systems. RNA-Seq analyses also revealed that GBM stem cells (GSC) with deletion of Plexin-B2 altered expression of genes related to cell adhesion and the matrisome, indicating compensatory mechanisms in cellular dynamics. Interestingly, in vivo intracranial transplant studies demonstrated that growth and invasion of Plexin-B2 mutant GSC was impaired, with mutant cells invading shorter distances and migrating mainly as groups of cells forming chains. Plexin-B2 mutant cells also were more likely to adhere to the vasculature, rather than to fiber tracts, suggesting altered biomechanical properties. This shift may be related to high stiffness of basal lamina of the vasculature, as Plexin-B2 KO cells have a preference for migration on stiff substrate in vitro. Intriguingly, the loss in Plexin-B2 expression also changed the distribution of the mechanosensor transction factor YAP, with high expression of Plexin-B2 correlating with increased nuclear YAP. Structure-function analyses revealed that the Ras-GAP domain as main signaling output of Plexin-B2. The Rap proteins are pleiotropic regulators of cell adhesion and actomysosin contractility. Our data also showed that overexpression of Plexin-B2 can lead to decreased levels of Rap1/Rap2. Thus, Plexin-B2 acts as a key regulator of the adhesion and contractility of GBM cells, thereby facilitating their diffuse invasion.

TMIC-59. INVESTIGATING PHYSIOLOGY OF THERAPY RESISTANT, TUMOR-INITIATING GBM CELLS IN HYPOXIC NICHES USING SPATIALLY-SENSITIVE HYPOXIA REPORTER SYSTEM AND SINGLE-CELL RNA SEQUENCING

Glioblastoma (GBM) is the most common and lethal brain cancer that invariably recurs after therapy due to presence of resistant GBM cells within hypoxic and peri-necrotic regions. Eradicating such GBM cells, which constitute a major source of tumor recurrence, is important to curb disease relapse. An endogenously expressed, spatially sensitive hypoxia reporter would therefore be a valuable tool to evaluate hypoxic zones in GBM in detail, and to measure the efficacy of hypoxia-activated drugs. For this purpose, we engineered a lentiviral vector that carries a hypoxia reporter, consisting of HIF response elements (HRE) that drive expression of UnaG fluorescent protein, which fluoresces independent of oxidative maturation. We validated the sensitivity of our reporter in vitro using U87MG, GBM2, and patient-derived GBM stem cell lines, and we performed intracranial transplantations of GBM cells in SCID mice to identify cells undergoing hypoxic stress in in vivo microenvironment. In addition, GL261 murine GBM cells with hypoxia reporter were intracranially implanted in C57BL/6 mice as syngeneic model for studies on immune responses. Brains from our transplant studies were dissociated and single-cell RNA sequencing (Drop-Seq) was performed to investigate heterogeneity in response to hypoxia within GBM cells and the cellular composition of microenvironment. We will also apply a hypoxia-activated prodrug, Evofosfamide (Evo), in our ongoing studies that can potentially eradicate hypoxic tumor cells and increase T cell infiltration and reverse immune suppression. As hypoxic niches are thought to confer resistance to radiation therapy (XRT), combining XRT with Evo could thus improve therapy efficacy. Our hypoxia gene reporter, combined with single-cell transcriptomics, could therefore serve as an effective tool to enable fundamental investigation of GBM microenvironment and could be used to evaluate therapies targeting tumor microenvironment to enhance GBM patient survival.

Outcome prediction in microsurgery by quantitative evaluation of perfusion using ICG fluorescence angiography

The purpose of this prospective study was to evaluate the clinical efficacy of laser-induced fluorescence angiography with indocyanine green (ICG-FA) for perioperative monitoring of tissue perfusion in hand surgery. Different quantitative parameters of the uptake, distribution and clearance of dye-marked blood were evaluated for their sensitivity and prognostic value in comparison to each other and to clinical parameters. One hundred and fifty-five measurements were performed prior to, or following, surgery for severe hand injuries. All quantitative parameters of ICG-FA detected intraoperatively were found to be of significant predictive value for outcome, but clinical parameters were not. For the dye uptake, a minimum slope value of 0.01 was significantly related to sufficient perfusion and good prognosis. There was no correlation between the quantitative ICG-FA results or any of the clinical parameters. Since clinical evaluation of perfusion in this surgery remains difficult, the additional use of ICG-FA may improve surgical decision making and, thereby, lead to better clinical results.

[Fixation of periprosthetic femur fractures with the less invasive stabilization system (LISS)--a new minimally invasive treatment with locked fixed-angle screws]

The Less Invasive Stabilization System (LISS) is a minimally invasive technique indicated for fixation of periprosthetic fractures. This new system allows percutaneous placement of cortical-shaft screws and fixation of the fracture with fixed-angle locked screws with minimal surgical exposure of the mostly osteoporotic bone and without disturbance of the existing total joint replacement. Immediate range-of-motion exercises are begun postoperatively. A retrospective clinical review of 5 patients (2 total hip arthroplasties, 3 total knee arthroplasties) was performed to describe indications, surgical technique, intra- and postoperative complications and patient follow-up. Indications are periprosthetic distal femur fractures, per- and supracondylar fractures. Contraindications are none, except existing medical comorbidities. Extraarticular fractures were treated via stab incisions over the lateral femoral condyle. Fractures with intraarticular displacement were fixed via an anterolateral parapatellar approach to the knee joint. After anatomic reduction of femoral condyles, articular fragments are fixed with Kirschner wires, followed by closed reduction aligning the articular fragments controlling length, axis and rotation. The LISS is introduced proximally under the M. vastus lateralis along the femur. It is fixed with self-drilling cortical shaft screws, locked fixed-angle screws both proximally and distally. Range-of-motion exercises are begun on the second day postoperatively. Time to full weight bearing averaged 6-8 weeks depending on clinical and radiological findings. Benefits of the LISS technique include the minimally invasive approach with increased primary stability using monocortical fixings thus eliminating the need for spongiosaplasty and blood transfusion. Disadvantages of the percutaneous placement of the LISS include malplacement on the femur, proximal screw pull-out and postoperative rotational and axial malalignment.

[Microvascular complications following replantations and revascularisations]

PURPOSE/BACKGROUND

What are the options for early diagnosis, treatment and prevention of the occlusion of microvascular anastomosis after replantations? METHOD AND (CLINICAL) MATERIAL: This is a retrospective analysis of 336 cases involving primary microvascular repair after an injury between 1984 and 2000. In 272 cases this was a revascularisation and in 187 a replantation. In 23 cases the vascular anastomosis was located proximal to the wrist (macroreplantations) and 313 times distal to it (microreplantations/-revascularisations).

RESULTS

Vascular complications developed in seven and 54 cases respectively. 40 % of these 61 patients showed a severe soft tissue compromise or/and had sustained an injury known to cause widespread intima lesions (15 avulsions, six crush injuries, one blast, one gun shoot, one RTA). 37 of the 61 patients had been injured by circulating saws. There were 34 arterial and 22 venous occlusions, four no-reflow-syndromes and one HIT-syndrome. Almost 90 % of these vascular complications occurred within the first four post-operative days, 50 % even within the first 36 hours. Treatment was surgical in 39/61 cases and conservative 22 times. In 55 % (33/61) of all cases this treatment was successful.

CONCLUSION

With an overall incidence of 1 : 6 vascular crisis is not only the most consequential but also the most common post-operative complication after replantations. Timely operative and/or non-operative therapeutic measures can save more than half of the replants affected.

[Late results following avulsion injuries of the thumb]

Out of the 127 amputated thumbs replanted at our unit during the last 15 years, there were 27 avulsion injuries. The average age of the 24 male patients was 33 years, that of the three female patients was 34 years. 70 % of the injuries were occupational accidents. Among the 27 patients, 21 had a complete and six an incomplete avulsion of the thumb. The level of avulsion-amputation was at the MP-joint ten times, between MP and IP joint ten times and at the IP-joint seven times. The healing rate of the subtotally avulsed thumbs was 100 %, that of the completely amputated thumbs 36 %. The most important post-operative complications observed were venous and secondary arterial thrombosis, whereby most of them occurred within the first 24 hours after replantation. The duration of ischaemia had a significant influence on the healing rate. In 80 % of the cases reconstruction of nerves have been carried out secondarily. A two-point discrimination was achieved in two cases only. The osteosynthesis was done almost exclusively with K-wires. Ten of 19 patients had to change their profession, while nine of them were able to return to their previous jobs, which in these cases were pre-dominantly white collar jobs. Another patient went for early retirement (he was a painter). All 19 patients followed-up had a range of movement of their saddle joints which was sufficient for the needs of most of the activities of daily life. Stiffness of the MP and IP joints was a common finding but had little functional impact, as it has been reported by other authors previously. We conclude from the results presented that in cases of avulsion injury of the thumb replantation is a procedure with significant chances of success.

Rapid functional plasticity of the somatosensory cortex after finger amputation

Recent research indicates that areas of the primary somatosensory (SI) and primary motor cortex show massive cortical reorganization after amputation of the upper arm, forearm or fingers. Most of these studies were carried out months or several years after amputation. In the present study, we describe cortical reorganization of areas in the SI of a patient who underwent amputation of the traumatized middle and ring fingers of his right hand 10 days before cortical magnetic source imaging data were obtained. Somatosensory-evoked magnetic fields (SEF) to mechanical stimuli to the finger tips were recorded and single moving dipoles were calculated using a realistic volume conductor model. Results reveal that the dipoles representing the second and fifth fingers of the affected hand were closer together than the comparable dipoles of the unaffected hand. Our findings demonstrate that neural cell assemblies in SI which formerly represented the right middle and ring fingers of this amputee became reorganized and invaded by neighbouring cell assemblies of the index and little finger of the same hand. These results indicate that functional plasticity occurs within a period of 10 days after amputation.

[The Marjolin's ulcer": a malignant and rarely complication after burn trauma of the upper extremity - a case report]

The,Marjolin's ulcer" is a malignant lesion which is developed especially at chronic wounds after burn trauma. The latency from primary trauma to the malignant transformation is about 30 years. The lesion is more aggressive than other squamous cell carcinomas. We report on the combined radiation and surgical therapy of an 65-year-old patient with this lesion on the right hand and regional lymph node metastases. The extensive tissue defect after wide excision was reconstructed with a reversal radial forearm flap.

[Fibrolipomatous hamartoma of the nerve--a rare etiology of macrodactyly. A case report]

Fibrolipomatous hamartoma of nerve is a rare, tumor-like fibro-fatty growth arising from the epi- and perineurium. It mainly affects peripheral nerves and the median nerve in particular. An association with Klippel-Trenaunay syndrome and macrodactyly has been described. We present a 30-year-old patient, in whom the diagnosis of Klippel-Trenaunay syndrome had been made at the age of two, based on macrodactyly of the right hand. Because of increasing functional limitation and pain, the patient was referred to our department, after angiographic exclusion of Klippel-Trenaunay syndrome, for operative reduction of the tumor. Histologic examination revealed a fibrolipomatous hamartoma of the nerve. Further treatment consisted of surgical tumor reduction, which resulted in satisfactory recovery of function in the right hand. After eight months follow-up, the patient was able to perform all normal daily activities, and there was no evidence of recurrence of the lesion. Diagnostic evaluation of macrodactyly is necessary, since there may be an underlying cause such as fibrolipomatous hamartoma of a nerve, which if corrected early by surgical excision may prevent long-term disability.

[Traumatic peripheral vascular injuries]

2-4% of vascular injuries need operative reconstruction. In polytraumatized patients the rate is even 10%. Arterial vascular repair should precede venous reconstruction and orthopaedic stabilization due to limb threatening ischemia. Penetration or blunt vascular trauma result either in acute blood loss, ischemia or compartmental compression. Reperfusion syndrome leads to vital threat of patient. Clinical assessment, measurement of limb pressures using a Doppler device and use of duplex ultrasonography are reliable adjuncts in the rapid evaluation. Arteriography is rarely indicated and should be spared for patients with abnormal physical examination. Minimizing ischemia (6-8 h) is an important factor in maximizing limb salvage. Vascular repair include direct anastomosis or lateral suture repair mostly combined with primary shortening of the extremity. In most cases autogenous vein graft is required. Rethrombosis, arteriovenous fistula and pseudoaneurysms are possible complications. Stabilisation of the fracture has priority over vascular reconstruction. The initial steps to success are surgical debridement, adequate bony stabilization mostly by external fixation, revascularisation of vascular injury, immediate fascial decompression and early soft-tissue reconstruction. The best results are obtained when a multidisciplinary approach is used combining expertise in orthopedic surgery, vascular surgery and plastic surgery.

[The treatment concept in severe hand injuries]

Treatment of complex injuries of the hand aims at best possible reconstruction of function and quick social and professional rehabilitation. This objective is hardly to achieve in most cases due to the severity of injury. Outcome depends on patients' age and injury pattern and essentially on the strategy of surgical treatment. Errors in prehospital emergency treatment can hardly be corrected, no matter how excellent the surgical technique may be. Traumatic multiple finger or thumb amputations are clear indications for replantation. Beginning with osteosynthesis, suture of tendons and ligaments the restoration of blood supply is the most important step. Nerve reconstruction should be performed immediately, but if tension free repair is impossible, secondary nerve grafting is preferred. Primary skin closure should be carried out if possible, in case of defects skin grafts, local or free flaps have to be used.

[Late outcome of severed extensor tendons in the area of the hand and fingers]

In the care and further treatment of patients with hand injuries, a necessary requirement of the hand surgeon is that he be able to cope with the interlocking factors that are no longer influential, for example, the type and extent of the trauma or the age of the patient; the influential factors are a thought-out care plan, atraumatic action with regard to optimal restoration of the hand. This also showed a retrospective analysis of results and post-examination from flexor tendon injuries in the hand of 298 patients, who were surgically cared for from 1984 to 1994 at the surgical clinic of the University of Jena. Of the 298 patients 119 patients with 198 flexor tendon injuries (165 fingers and 33 thumbs) were followed up. For objective assessment of the treatment results, the assessment scheme Buck-Gramcko was used.

[Functional fracture treatment of the upper arm]

Using a functional brace, we treated 67 patients who had a fracture of the humeral shaft over a 5-year period from 1987 to 1992. We analysed several parameters of the fractures to discover those which influence healing. Desault, plaster cast or traction were used before applying a brace in an average time of 15 days. The osseous consolidation was 10 weeks in the average. The functional results were very good and good in 78.3%, acceptable in 18.3% and poor in 3.4% of the cases. Twelve humeral-shaft fractures were associated with a radial nerve palsy. Every patient recovered a full radial nerve function under the treatment with a functional brace. The retentive management of an operative treatment of humeral-shaft fractures associated with a nerve injury can be supported because of our experience.

[Muscle incoordination phenomena after surgical management of proximal rupture of the biceps tendon]

A significant atrophy of the biceps brachii muscle without decreasing maximal force during flexion in the elbow joint was shown at least 1.5 years after surgical refixation in 6 patients with a tendon-rupture of the long head of the right biceps. A decreased myoelectrical activity was found in the caput longum region of the muscle. The decrease correlates with an increase of spectral myoelectrical power in the region of caput breve or brachioradialis muscle. In addition compensatory recruitment processes can be supposed because of changed spectral myoelectrical power in the low-frequency bands. Changes of the morphological structure of the muscle were only found in 1 patient by sonography.

[Proximal humerus shaft fracture as a complication after keyhole-plasty. A case report]

Six weeks after operative treatment of a rupture of the long head of biceps brachii using keyhole tenodesis on the left arm in a man 69 years old a fracture of the upper arm happened. The reason seems to be the localization of keyhole osteotomy being probably to much distal.

[Amputation injuries of the upper extremity--early complications after replantation and revascularization]

Within a time of ten years 144 patients with difficult injuries on their hands were operated. These were 95 replantations and 102 revascularizations. 26 patients had to be operated again because of arterial and venous thrombosis. 46% of our patients had early vascular complications already within 24 hours. The frequency of thrombosis was increasing with the accompanying soft tissue injury and therefore with the gravity of the trauma. Avulsion injuries had of course the worst prognosis. After diagnosis of vascular occlusion within the replanted finger there should be a quick surgical revision of the anastomosis. With the help of application of urokinase into the artery we could create the circulation without any new production of the anastomosis in two cases. With a subtile technique of the disposition of the anastomosis and two venous connections to one artery with the replanted fingers we could reduce the rate of thrombosis and improve the results.

Induction of an endothermic transition in the Arrhenius plot of fatty acid uptake by lipid-depleted ascites tumor cells

Cultured ascites tumor cells and their lipid-depleted variants containing 35-40% less membrane phospholipid and cholesterol were used to study uptake and metabolism of fatty acids complexed to albumin. Uptake of stearate and oleate at 37 degrees C was considerably higher in the lipid-depleted cells, but no significant difference in the affinity constants for stearate uptake of 3.70 microM for the lipid-depleted and 2.50 microM for the control cells was observed. Similar rates of uptake of both cultures were observed at lower temperatures up to 30 degrees C. The drastic increase in stearate uptake above 30 degrees C resulted in an endothermic transition in the Arrhenius plot with an activation energy of 20.8 kJ/mol versus 6.5 kJ/mol for the control cells. Uptake of stearate and oleate of the control cells was only slightly reduced by metabolic inhibitors, which was similar to stearic acid transport in the lipid-depleted variants. However, oleate uptake was substantially decreased in these variants. Incorporated stearate was esterified to about 50% in both cultures, and oleate between 85 and 90%. Mainly triacylglycerols and phospholipids with phosphatidylcholine (41%) and phosphatidylethanolamine (35%) as major polar lipid components, and also lower acylglycerols and cholesterol were found to be labeled. Under lipid-depleted conditions, a pronounced increase in the relative proportion of oleate incorporation into triacylglycerols was determined. It is suggested that fatty acid uptake is controlled by the number of active sites of the putative transport protein, which increases upon lipid depletion as shown from the V values. This increase may result from the segregation of membrane-bound proteins into domains (Haeffner et al. (1986) Cell Mol. Biol. 32, 359-368), which are known to be formed as a consequence of lipid phase separation in the lipid-depleted cells.

Tolerance and pharmacokinetics of oral fendiline

Two studies with healthy volunteers were carried out to correlate safety with pharmacokinetics of the calcium antagonistic drug N-(3,3-diphenylpropyl)-(1-phenylethyl)-amine (fendiline, Sensit) after single and multiple oral doses. In the first study single doses of 200, 400, 600, 800, 1000, and 1200 mg of fendiline hydrochloride were administered to 6 subjects per dose level. 3 additional subjects per dose level received placebo. No significant objective or subjective effects were noted in the dose range studied. The pharmacokinetic analysis revealed that doses higher than 800 mg were absorbed incompletely. In the second study initially 400 mg twice daily was given to 9 subjects. 3 additional subjects received placebo. Due to subjective intolerability (trembling, dizziness) after 5 days, the dose was reduced stepwise to 2 X 200 mg and was then continued for another 19 days. The pharmacokinetic evaluation revealed manifold interindividual differences in plasma levels for maximal concentrations (9-170 ng/ml) as well as for minimal concentrations (4-96 ng/ml). The absorption profile in both studies has linear and nonlinear components. Maximal plasma levels were reached after about 4 h. Terminal elimination half-lives were about 20 h.

Structural and functional alterations of lipid-depleted ascites tumor cells in culture

Ascites tumor cells growth-arrested in lipid-depleted medium were modified with respect to their lipid composition, i.e. mainly cholesterol and the phospholipid fraction. These so-called lipid-depleted cells were generally smaller, had a surface area reduced by 55% compared to the control cells and had an altered cell surface architecture with large parts being smooth, interrupted by isolated bundles of microvilli and blebs as revealed by scanning electron microscopy. This deorganization process of the cells. Lectin-induced agglutination and receptor binding capacity was reduced, and also the receptor distribution was changed resulting in a cap-like formation on the surface as shown with FITC-labelled concanavalin A. The reduction in lipid content yielding a lower C/P ratio profoundly decreased the plasma membrane fluidity which was determined by fluorescence polarization measurements. Studies on fatty acid and cholesterol de novo synthesis revealed only small increases under lipid-free conditions not sufficient to meet the requirements of the lipid-depleted cells for these substances. It is therefore concluded that ascites tumor cells need exogenous preformed lipids for adequate functioning of the cell.

Long-term observation of plasma and tissue enzyme activities in the rat

During a long-term study in the rat some enzyme activities were determined in plasma, lung, spleen and skeletal muscle. Twelve rats of each sex were investigated every 49 days from 35 until 1115 days of life. Lactate dehydrogenase in lung and spleen decreases; in muscle and plasma, however, the activity varies considerably. Malate dehydrogenase in the tissues remains nearly unchanged apart from distinct peaks in the first year of life; in plasma the activity takes an M-shaped course. In contrast to the changes of glutamate dehydrogenase in the tissues with a tendency to diminish, this enzyme increases in plasma during the lifetime. Aspartate aminotransferase activity in the tissues, except muscle, varies with a rhythmical behaviour, and in plasma shows a gradual increase. Alanine aminotransferase in lung and spleen has two activity peaks. In muscle this enzyme varies only slightly after a steep initial decrease. In plasma the activity has a tendency to rise. Creatine kinase in the tissues reveals several activity peaks. In plasma the activity course is U-shaped. Adenylate kinase in spleen and lung rises, whereas in muscle the activity varies considerably. The nearly identical decrease of alkaline phosphatase activity in the tissues during ageing is also reflected by a concomitant behaviour in plasma. Leucine arylamidase in lung and muscle both have a U-shaped characteristic, whereas in spleen the activity changes in a shorter period. In plasma, a rhythmical behaviour is apparent. Aldolase in plasma tripled during the observation period. Except for lactate dehydrogenase and aldolase, distinct sex-differences are observed in plasma. With progressive age the animals suffer increasingly from characteristic diseases, which beside experimental components have influenced the enzyme pattern. Enzyme activities in plasma and tissues show a complex pattern and are only of limited importance in understanding the ageing process.

Capillary radioimmunoassay of insulin

Capillary radioimmunoassay -- a modification of the coated tube technique -- is described. The assay is equivalent (accuracy, sensitivity, precision) to conventional methods for insulin determination; it overcomes, however, the necessity of centrifugation or filtration and offers the added bonus of being automation compatible.

Stress response of rats to handling and experimental procedures

The effects were observed of moving male, adult Han:Sprague rats in their cages or of exposure to ether for 1 min on the plasma concentration profiles of 25 blood characteristics linked with stress and shock reactions. 5 min after the stress serum prolactin, corticosterone, thyroid-stimulating hormone, follicle-stimulating hormone, luteinizing hormone, triiodothyronine and thyroxin levels were elevated 150-500% compared with those in blood collected within 100 s of entering the animal room.

Heart rate (telemetrically recorded), packed cell volume,, haemoglobin and plasma protein content were 10-20% elevated 2-10 min after cage movement or 2-20 min after ether confrontation over those of controls sampled within 50 s, indicating circulatory and microcirculatory shock reactions.

Serum glucose, pyruvate and lactate concentrations rose by 20-100% 1-5 min after cage movement and 1-15 min after ether exposure. Phosphate, calcium, urea, apartate and alanine transferases, alkaline phosphalase and leucine arylamidase were not altered significantly by either stressor, while potassium and bound glycerol fell for 1 min and 5-20 min respectively.

The presence of a familiar animal attendant working in the room without touching the cages did not markedly affect the blood characteristics being studied.

Lymphatic transport of cellular enzymes from muscle into the intravascular compartment

In an experimental study, employing anaesthetized dogs, it was investigated whether cellular enzymes from peripheral skeletal muscle get into the circulating blood by diffusion across capillary membranes or by lymphatic transport. In the experimental group 1, the animals were anaesthetized only. The plasma activities of the four enzymes measured--lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, creatine kinase--did not show any mentionable change during a time period of 6 h. In group 2 one hind limb of each animal was moved passively for 1 h. Alanine aminotransferase remained unchanged in plasma, the activities of the three other enzymes increased significantly. In group 3 one hind limb was made hypoxic by clamping the femoral blood vessels for 1 h. No activity changes were observed. When the period of hypoxia was followed by a 1-hour period of passive movement in group 4, the alterations in plasma activities were almost identical to those observed in group 2. In group 5 the experimental procedure was as in group 4, in addition the lymph from the thoracic duct was quantitatively withdrawn. The enzyme activities in plasma revealed a tendency to decrease rather than increase. Lymph flow increased significantly as well as the lymphatic activities of those enzymes which have high intracellular activities in muscle. The results prove, that enzymes from muscle are transported from the interstitial into the intravascular compartment mainly by lymphatic transport. Indications were found that the interruption of blood flow in one hind limb did not result in an enzyme release from muscle cells. It is discussed how changes in lymph flow, occurring during physical exercise for example, affect enzyme activities in plasma.

On the mechanism of lactate dehydrogenase release from skeletal muscle in relation to the control of cell volume

The mechanism of enzyme release from isolated skeletal muscle was illustrated by the study of the release of lactate dehydrogenase (LDH). In hypotonic media of different composition but of same tonicity the increase of LDH permeability was triggered at the same range of relative osmolality R (0.45 less than R less than 0.55), although the swelling in the respective media showed appreciable differences. The kinetics of muscle swelling showed that a deviation from the theoretically computed swelling curve to lower values of swelling was connected with an increased LDH permeability. The reduction of swelling was ATP- and Ca2+ and/or Mg2-dependent. It is concluded that swelling of cells generally precedes the leakage of soluble enzymes, and the cross-linking of filaments at the sarcoplasmic side of the sarcolemma under appropriate conditions can counteract swelling, thereby blebbing off the cell membrane from the filament meshwork. In the course of this process, sufficiently large membrane lesions are produced through which macromolecules may escape into the extracellular space.

Combined batchwise and continuous flow mechanization of solid-phase radioimmunoassays

A new modification of the "coated-tube"-technique for the radioimmunoassay of human placental lactogen is described. Polyvinylchloride capillaries are used as reaction-vessels. Most working steps of the test procedure are mechanized. The possibilities and limitations of the new technique are discussed. The reliability of the method was shown by a recovery test, dilution tests, reproducibility and a comparison of the results for 71 sera, ranging from the 6th to the 42nd week of pregnancy, with those obtained by a conventional assay procedure.

[A system for the mechanized radioimmunological determination of digoxin]

Because of the increased number of samples to be processed in digoxin radioimmunoassay for clinical diagnosis and pharmacokinetic studies these analyses require mechanization to a certain extent. A newly developed modular analyzer system is described which is capable of mechanizing radioimmunoassays for digoxin, for example, independent on the kind of reagent kits as well as the separation technique. In dependence on the number of replicates from 60 to 240 samples per hour can be processed. The reaction vessels are placed in belts during the whole assay including centrifugation. The final separation of the liquid and the solid phase after centrifugation can be performed in two different ways: 1. If a conventional automatic gamma counter is used an aliquot of the supernatant is automatically dispensed into the counting vials which are to be closed manually and transferred into the counting device. 2. Further reduction of manual working steps can be achieved by employment of a newly developed discontinuous flow-through gamma counter which is part of the modular analyzer system. An aliquot of the supernatants is automatically flushed into a measuring cuvette installed into a conventional crystal detector. After measurement of the radioactivity and data output the cuvette is rinsed thoroughly. Thereafter the following sample is delivered.

Release of enzymes from cells: transport and distribution within the extracellular space

The distribution in the extracellular space of enzymes released from organ cells was investigated using three models: (1) comparison of enzyme activities in blood plasma and lymph of the ductus thoracicus (dog) and plasma and intestinal lymph (rat); (2) i.v. injection of heterologous, homologous and autologous enzymes in order to increase acutely the activities and to measure the rate constants for the distribution and elimination of the enzymes (rat); or (3) plasmapheresis in order to create an enzyme activity gradient from the interstitial space and to determine the rate constants for the reestablishment of the equilibrium between the extra and intravascular compartments (rat). The results suggest that the enzymes are mainly released into the interstitial fluid and transported via the lymph into the intravascular compartment. From there the enzymes diffuse back into the interstitial compartment and are eliminated by a yet unknown mechanism. Transport of enzymes across the capillary membranes in both directions depends on (1) the permeability of the capillary membranes, which varies from region to region and (2) the molecular seizes of the enzymes.

[Cell enzymes in lymph. Distribution and transport of cell enzymes within the extracellular space. II (author's transl)]

Enzyme patterns were measured in the lymph of the thoracic duct of the dog and in the intestinal lymph of the rat. Those patterns were compared to the corresponding activities in blood plasma. From the results it is concluded that under physiological conditions cell enzymes are released into the interstitial space and from there are transported via the lymph into the intravascular space. Only enzymes with a low molecular weight such as myokinase are able to penetrate the capillary membrane, thereby reaching the plasma without being transported exclusively by the lymph. There is a close relationship between the molecular weight of enzymes and their plasma/lymph ratios. In the rat the enzyme patterns in mesenteric lymph nodes and in intestinal mucosa and muscularis (duodenum as well as ileum) were also determined. No direct correlation between those intracellular patterns and the enzyme patterns in the intestinal lymph could be established. The significance of lymph and lymph flow for clinical enzymology is discussed with respect to physiological and pathological conditions. High sensitivity of diagnosis by means of enzyme measurements in plasma can be achieved only if the capillary permeability in the injured organ is high and/or the lymph flow from the organ is not restricted by the injury.