Amisulpride as a potential disease-modifying drug in the treatment of tauopathies

INTRODUCTION

Hyperphosphorylation and aggregation of the microtubule-associated protein tau cause the development of tauopathies, such as Alzheimer's disease and frontotemporal dementia (FTD). We recently uncovered a causal link between constitutive serotonin receptor 7 (5-HT7R) activity and pathological tau aggregation. Here, we evaluated 5-HT7R inverse agonists as novel drugs in the treatment of tauopathies.

METHODS

Based on structural homology, we screened multiple approved drugs for their inverse agonism toward 5-HT7R. Therapeutic potential was validated using biochemical, pharmacological, microscopic, and behavioral approaches in different cellular models including tau aggregation cell line HEK293 tau bimolecular fluorescence complementation, primary mouse neurons, and human induced pluripotent stem cell-derived neurons carrying an FTD-associated tau mutation as well as in two mouse models of tauopathy.

RESULTS

Antipsychotic drug amisulpride is a potent 5-HT7R inverse agonist. Amisulpride ameliorated tau hyperphosphorylation and aggregation in vitro. It further reduced tau pathology and abrogated memory impairment in mice.

DISCUSSION

Amisulpride may be a disease-modifying drug for tauopathies.

Induced Remodelling of Astrocytes In Vitro and In Vivo by Manipulation of Astrocytic RhoA Activity

Structural changes of astrocytes and their perisynaptic processes occur in response to various physiological and pathophysiological stimuli. They are thought to profoundly affect synaptic signalling and neuron-astrocyte communication. Understanding the causal relationship between astrocyte morphology changes and their functional consequences requires experimental tools to selectively manipulate astrocyte morphology. Previous studies indicate that RhoA-related signalling can play a major role in controlling astrocyte morphology, but the direct effect of increased RhoA activity has not been documented in vitro and in vivo. Therefore, we established a viral approach to manipulate astrocytic RhoA activity. We tested if and how overexpression of wild-type RhoA, of a constitutively active RhoA mutant (RhoA-CA), and of a dominant-negative RhoA variant changes the morphology of cultured astrocytes. We found that astrocytic expression of RhoA-CA induced robust cytoskeletal changes and a withdrawal of processes in cultured astrocytes. In contrast, overexpression of other RhoA variants led to more variable changes of astrocyte morphology. These induced morphology changes were reproduced in astrocytes of the hippocampus in vivo. Importantly, astrocytic overexpression of RhoA-CA did not alter the branching pattern of larger GFAP-positive processes of astrocytes. This indicates that a prolonged increase of astrocytic RhoA activity leads to a distinct morphological phenotype in vitro and in vivo, which is characterized by an isolated reduction of fine peripheral astrocyte processes in vivo. At the same time, we identified a promising experimental approach for investigating the functional consequences of astrocyte morphology changes.

Activation of the 5-HT7 receptor and MMP-9 signaling module in the hippocampal CA1 region is necessary for the development of depressive-like behavior

Major depressive disorder is a complex disease resulting from aberrant synaptic plasticity that may be caused by abnormal serotonergic signaling. Using a combination of behavioral, biochemical, and imaging methods, we analyze 5-HT7R/MMP-9 signaling and dendritic spine plasticity in the hippocampus in mice treated with the selective 5-HT7R agonist (LP-211) and in a model of chronic unpredictable stress (CUS)-induced depressive-like behavior. We show that acute 5-HT7R activation induces depressive-like behavior in mice in an MMP-9-dependent manner and that post mortem brain samples from human individuals with depression reveal increased MMP-9 enzymatic activity in the hippocampus. Both pharmacological activation of 5-HT7R and modulation of its downstream effectors as a result of CUS lead to dendritic spine elongation and decreased spine density in this region. Overall, the 5-HT7R/MMP-9 pathway is specifically activated in the CA1 subregion of the hippocampus during chronic stress and is crucial for inducing depressive-like behavior.

Elucidating regulators of astrocytic Ca2+ signaling via multi-threshold event detection (MTED)

Recent achievements in indicator optimization and imaging techniques promote the advancement of functional imaging to decipher complex signaling processes in living cells, such as Ca²⁺ activity patterns. Astrocytes are important regulators of the brain network and well known for their highly complex morphology and spontaneous Ca²⁺ activity. However, the astrocyte community is lacking standardized methods to analyze and interpret Ca²⁺ activity recordings, hindering global comparisons. Here, we present a biophysically-based analytical concept for deciphering the complex spatio-temporal changes of Ca²⁺ biosensor fluorescence for understanding the underlying signaling mechanisms. We developed a pixel-based multi-threshold event detection (MTED) analysis of multidimensional data, which accounts for signal strength as an additional signaling dimension and provides the experimenter with a comprehensive toolbox for a differentiated and in-depth characterization of fluorescence signals. MTED was validated by analyzing astrocytic Ca²⁺ activity across Ca²⁺ indicators, imaging setups, and model systems from primary cell culture to awake, head-fixed mice. We identified extended Ca²⁺ activity at 25°C compared to 37°C physiological body temperature and dissected how neuronal activity shapes long-lasting astrocytic Ca²⁺ activity. Our MTED strategy, as a parameter-free approach, is easily transferrable to other fluorescent indicators and biosensors and embraces the additional dimensionality of signaling activity strength. It will also advance the definition of standardized procedures and parameters to improve comparability of research data and reports.

S-Palmitoylation of Synaptic Proteins as a Novel Mechanism Underlying Sex-Dependent Differences in Neuronal Plasticity

Although sex differences in the brain are prevalent, the knowledge about mechanisms underlying sex-related effects on normal and pathological brain functioning is rather poor. It is known that female and male brains differ in size and connectivity. Moreover, those differences are related to neuronal morphology, synaptic plasticity, and molecular signaling pathways. Among different processes assuring proper synapse functions are posttranslational modifications, and among them, S-palmitoylation (S-PALM) emerges as a crucial mechanism regulating synaptic integrity. Protein S-PALM is governed by a family of palmitoyl acyltransferases, also known as DHHC proteins. Here we focused on the sex-related functional importance of DHHC7 acyltransferase because of its S-PALM action over different synaptic proteins as well as sex steroid receptors. Using the mass spectrometry-based PANIMoni method, we identified sex-dependent differences in the S-PALM of synaptic proteins potentially involved in the regulation of membrane excitability and synaptic transmission as well as in the signaling of proteins involved in the structural plasticity of dendritic spines. To determine a mechanistic source for obtained sex-dependent changes in protein S-PALM, we analyzed synaptoneurosomes isolated from DHHC7-/- (DHHC7KO) female and male mice. Our data showed sex-dependent action of DHHC7 acyltransferase. Furthermore, we revealed that different S-PALM proteins control the same biological processes in male and female synapses.

Amelioration of Tau pathology and memory deficits by targeting 5-HT7 receptor

Tauopathies comprise a heterogeneous family of neurodegenerative diseases characterized by pathological accumulation of hyperphosphorylated Tau protein. Pathological changes in serotonergic signaling have been associated with tauopathy etiology, but the underlying mechanisms remain poorly understood. Here, we studied the role of the serotonin receptor 7 (5-HT7R), in a mouse model of tauopathy induced by overexpressing the human Tau[R406W] mutant associated with inherited forms of frontotemporal dementia. We showed that the constitutive 5-HT7R activity is required for Tau hyperphosphorylation and formation of highly bundled Tau structures (HBTS) through G-protein-independent, CDK5-dependent mechanism. We also showed that 5-HT7R physically interacts with CDK5. At the systemic level, 5-HT7R-mediated CDK5 activation induces HBTS leading to neuronal death, reduced long-term potentiation (LTP), and impaired memory in mice. Specific blockade of constitutive 5-HT7R activity in neurons that overexpressed Tau[R406W] prevents Tau hyperphosphorylation, aggregation, and neurotoxicity. Moreover, 5-HT7R knockdown in the prefrontal cortex fully abrogates Tau[R406W]-induced LTP deficits and memory impairments. Thus, 5-HT7R/CDK5 signaling emerged as a new, promising target for tauopathy treatments.

Serotonin receptor 4 regulates hippocampal astrocyte morphology and function

Astrocytes are an important component of the multipartite synapse and crucial for proper neuronal network function. Although small GTPases of the Rho family are powerful regulators of cellular morphology, the signaling modules of Rho-mediated pathways in astrocytes remain enigmatic. Here we demonstrated that the serotonin receptor 4 (5-HT₄ R) is expressed in hippocampal astrocytes, both in vitro and in vivo. Through fluorescence microscopy, we established that 5-HT₄ R activation triggered RhoA activity via Gα₁₃ -mediated signaling, which boosted filamentous actin assembly, leading to morphological changes in hippocampal astrocytes. We investigated the effects of these 5-HT₄ R-mediated changes in mixed cultures and in acute slices, in which 5-HT₄ R was expressed exclusively in astrocytes. In both systems, 5-HT₄ R-RhoA signaling changed glutamatergic synaptic transmission: It increased the frequency of miniature excitatory postsynaptic currents (mEPSCs) in mixed cultures and reduced the paired-pulse-ratio (PPR) of field excitatory postsynaptic potentials (fEPSPs) in acute slices. Overall, our present findings demonstrate that astrocytic 5-HT₄ R-Gα₁₃ -RhoA signaling is a previously unrecognized molecular pathway involved in the functional regulation of excitatory synaptic circuits.

Amelioration of Tau pathology and memory deficits by targeting 5-HT7 receptor

Tauopathies comprise a heterogeneous family of neurodegenerative diseases characterized by pathological accumulation of hyperphosphorylated Tau protein. Pathological changes in serotonergic signaling have been associated with tauopathy etiology, but the underlying mechanisms remain poorly understood. Here, we studied the role of the serotonin receptor 7 (5-HT7R), in a mouse model of tauopathy induced by overexpressing the human Tau[R406W] mutant associated with inherited forms of frontotemporal dementia. We showed that the constitutive 5-HT7R activity is required for Tau hyperphosphorylation and formation of highly bundled Tau structures (HBTS) through G-protein-independent, CDK5-dependent mechanism. We also showed that 5-HT7R physically interacts with CDK5. At the systemic level, 5-HT7R-mediated CDK5 activation induces HBTS leading to neuronal death, reduced long-term potentiation (LTP), and impaired memory in mice. Specific blockade of constitutive 5-HT7R activity in neurons that overexpressed Tau[R406W] prevents Tau hyperphosphorylation, aggregation, and neurotoxicity. Moreover, 5-HT7R knockdown in the prefrontal cortex fully abrogates Tau[R406W]-induced LTP deficits and memory impairments. Thus, 5-HT7R/CDK5 signaling emerged as a new, promising target for tauopathy treatments.

Spermidine protects from age-related synaptic alterations at hippocampal mossy fiber-CA3 synapses

Aging is associated with functional alterations of synapses thought to contribute to age-dependent memory impairment (AMI). While therapeutic avenues to protect from AMI are largely elusive, supplementation of spermidine, a polyamine normally declining with age, has been shown to restore defective proteostasis and to protect from AMI in Drosophila. Here we demonstrate that dietary spermidine protects from age-related synaptic alterations at hippocampal mossy fiber (MF)-CA3 synapses and prevents the aging-induced loss of neuronal mitochondria. Dietary spermidine rescued age-dependent decreases in synaptic vesicle density and largely restored defective presynaptic MF-CA3 long-term potentiation (LTP) at MF-CA3 synapses (MF-CA3) in aged animals. In contrast, spermidine failed to protect CA3-CA1 hippocampal synapses characterized by postsynaptic LTP from age-related changes in function and morphology. Our data demonstrate that dietary spermidine attenuates age-associated deterioration of MF-CA3 synaptic transmission and plasticity. These findings provide a physiological and molecular basis for the future therapeutic usage of spermidine.

NDUFA4 expression in clear cell renal cell carcinoma is predictive for cancer-specific survival

Like other cancers, renal cell carcinoma (RCC) derives the essential energy for proliferation and survival from high rates of glycolysis rather than from oxidative phosphorylation of the mitochondrial respiration pathway. NDUFA4 (NADH Dehydrogenase (Ubiquinone) 1 Alpha Subcomplex, 4) is encoding a protein belonging to the respiratory chain of mitochondria. For a better understanding of the tumor biology and for identification of a potential new biomarker, we analyzed the regulation of NDUFA4 in RCC compared to normal tissue cells. Downregulation of NDUFA4 mRNA and protein was detected in RCC compared to normal renal tissues in quantitative real-time PCR as well as in western blot and immunohistochemical staining. Histological analysis revealed higher NDUFA4 expression in the distal tubules compared to the proximal tubules and the loop of Henle. A higher molecular weight of the NDUFA4 protein was discovered in RCC samples, possibly indicating a posttranslational modification. Moreover, NDUFA4 protein expression was predictive for cancer-specific survival. Our analysis revealed a potential new biomarker, but future studies are warranted to investigate the prognostic value of NDUF4A expression.

Otto Hilgenfeldt (1900-1983): tribute to an important pioneer of European hand surgery

The German surgeon Otto Hilgenfeldt (1900-1983) was a great innovator in European hand surgery in the 20th century, particularly in respect of the tactile (sensate) thumb and grip reconstruction in amputation injuries. His experience, beginning in the 1930s, helped him to treat hundreds of soldiers with mutilating hand injuries from 1941 to 1945 during World War II. While totally isolated and without any access to international publications, he devised many innovative ideas such as a neurovascular middle finger transposition for pollicization (first case done in July 1943) and a sensory dorsoradial first metacarpal flap for thumb resurfacing. His book Operative thumb replacement and substitution of finger losses published in 1950 is regarded as one of the most important German contributions to modern hand surgery. Hilgenfeldt's life and work remain fascinating and exemplary from a historical and surgical point of view. Many of his pragmatic surgical solutions remain valid despite the advent of microsurgery.

Interleukin 6--a potential mediator of lethal sepsis after major thermal trauma: evidence for increased IL-6 production by peripheral blood mononuclear cells

We studied the plasma levels of the acute phase mediator interleukin 6 (IL-6) in 21 severely burned patients (burn injuries ranging from 24% to 75% total body surface area). The posttraumatic course of the IL-6 plasma levels was closely related to the clinical outcome. The nonseptic survivors as well as survivors with suspected sepsis (n = 14) exhibited maximal amounts of IL-6 (251 +/- 32 pg/mL) during the first 3 days post-burn, which subsequently returned to values within the normal range (days 30 to 50; 26 +/- 8 pg/mL). In the nonsurvivors (n = 7) IL-6 concentrations permanently increased (up to 1,921 +/- 356 pg/mL) until death (days 10 to 19) resulting from sepsis with consecutive multiple organ failure. Peripheral blood mononuclear cells (PBMCs) of patients expressed IL-6-specific mRNA in vivo at high levels in contrast to the PBMCs of healthy donors. In addition, the spontaneous and PHA-induced in vitro production of IL-6 by patients' PBMCs was enhanced compared with healthy controls, whereas no significant differences were obtained with bacterial endotoxin (LPS). The findings suggest that interleukin 6 is a potential mediator of lethal sepsis after major thermal trauma.

Serum CD14 levels in polytraumatized and severely burned patients

Recently it has been demonstrated that the CD14 molecule which is expressed on monocytes and macrophages serves as a receptor for lipopolysaccharide (LPS) bound to LPS-binding protein (LBP) and thus mediates LPS-induced tumour necrosis factor (TNF) production. Here we report that CD14 is found as a soluble (s) molecule in serum. In healthy volunteers sCD14 levels (mean +/- s.e.m.) were 3.7 +/- 0.05 micrograms/ml (n = 30, 25-50 years of age) as determined by ELISA (detection limit 20 ng/ml serum) using two monoclonal antibodies in a sandwich technique. In polytraumatized patients (n = 16) significantly decreased levels (1.7 +/- 0.3) were detected immediately after the trauma, which increased to 4.9 +/- 0.3 micrograms/ml within the first 6 days post trauma. sCD14 remained elevated during the first 14 days post trauma in patients with the most severe injuries (injury severity score greater than 45 points), whereas a return to normal levels was observed in patients with an injury score of less than 45 points. In addition, the levels of the high-density lipoproteins that partially inactivate free endotoxin are significantly decreased post trauma. No correlation between parameters of inflammation (C3a and neopterin levels, leucocyte counts, amount of band cells), liver function and sCD14 levels was established. Comparable to polytraumatized patients, increased sCD14 serum levels were observed in five patients with burn trauma (burned area greater than 35%) within the second week post trauma when clinical signs of septicaemia were evident.

Differential regulation of T- and B-lymphocyte activation in severely burned patients

We studied the in vitro expression and regulation of the CD23 and CD25 (Tac) surface antigens by peripheral blood lymphocytes (PBL) from severely burned patients (burn injuries ranging from 25% to 72% TBSA) in order to evaluate T- and B-lymphocyte activation processes after thermal trauma. The spontaneous and cytokine (IL-4, IL-2)-induced expression of CD23 which represents a B-cell activation marker was significantly reduced during the second to fifth week postburn when compared to healthy donors. In contrast, CD25, which is expressed on activated T cells, showed a marked increase both spontaneously, indicating an in vivo activation, and after stimulation with IL-2 or PHA. Concomitantly, T-cell proliferation induced by PHA or Con A was suppressed. However, the number of T and B cells remained unchanged. The data demonstrate the impairment of early events in the lymphocyte program in severely burned patients. The activation of B cells is downregulated, since they become refractory to external helper signals. In addition, T cells are highly activated but fail to proceed to proliferation in response to mitogenic stimuli.

Metabolism of platelet activating factor (PAF) and lyso-PAF in polymorphonuclear granulocytes from severely burned patients

We studied the metabolism of 3H-platelet activating factor (PAF) and lyso-PAF in human polymorphonuclear granulocytes (PMN) from severely burned patients (n = 6) on days 1, 5, 9, 15, and 25 post-trauma. All patients suffered from a severe burn trauma of more than 30% total body surface area. Stimulation of PMN in healthy donors (n = 10) with the Ca-ionophore resulted in the conversion of 3H-lyso-PAF into PAF (18 +/- 2% of total radioactivity) and alkyl-acyl-glycero-phosphorylcholine (alkyl-acyl-GPC, 50 +/- 6%). In burned patients a significantly reduced formation of 3H-PAF was observed between days 1 and 15 post-trauma (day 9: 1 +/- 1%, p less than 0.0001). This pattern was normalized again in patients (n = 5) who survived the trauma after septic periods and was observed during the second week post-trauma. In one patient who succumbed to his injuries a sustained inhibition of PAF formation was observed up to his death. The decreased formation of PAF correlated weakly with the appearance of immature granulocytes within the analyzed cell fraction (ratio of immature cells versus PAF-formation, r = -0.55, p = 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Basophil releasability in severely burned patients

Thermal injury is known to induce dysregulation of the immune system; however, the precise mechanisms have to be clarified. We investigated the histamine release of basophil granulocytes from severely burned patients (n = 12) after stimulation with anti-IgE or the Ca-ionophore A 23187, respectively. The anti-IgE-induced basophil histamine release of all patients was reduced in comparison to healthy donors beginning at day one postburn (p.b.) (5.0 +/- 2.3% vs. 30.5 +/-3.4%), while the Ca-ionophore-induced release was not decreased before day two p.b. Basophils of patients who finally succumbed to their injuries showed poor responsiveness (to zero levels) over the total time. In contrast, the basophil releasability of surviving patients returned to nearly normal levels (fifth to seventh week p.b.). Already in the second week p.b. there was a significant difference in histamine release between survivors and nonsurvivors [e.g., days 6-9 p.b.: 23.7 +/- 4.0 vs. 6.9 +/- 2.7 (p less than 0.005) after Ca-ionophore stimulation]. The altered basophil histamine release was neither due to a diminished dose- or a delayed time-response to the stimuli nor due to differences in the basophil counts or the cellular histamine content. Our data indicate that the decrease of the basophil releasability, which may be secondary to altered signal transduction pathways in severely burned patients correlates with the clinical outcome.

Studies on B-lymphocyte dysfunctions in severely burned patients

We studied in vitro functional parameters of peripheral blood B-lymphocytes from severely burned patients (n = 10; burn injuries ranging from 25 to 72% TBSA). While the number of B-cells remained unchanged, B-cell proliferation induced by Staphylococcus aureus strain Cowan I (SAC) was normal or even enhanced at early and late phases postburn, but showed a marked suppression during the second to fourth week. A similar pattern was observed for the pokeweed mitogen (PWM)- or SAC-stimulated synthesis of immunoglobulin M (IgM), whereas IgG production was decreased over the whole postburn period monitored. Cytokine (interleukin 4)-induced B-cell activation as indicated by the expression of the CD23 surface antigen was impaired throughout the second to fifth week. In parallel, the release of the proteolytic cleavage product sCD23 which represents a B-cell growth and differentiation factor was reduced. Our data provide evidence that activation, proliferation, and differentiation processes of B-lymphocytes are impaired in severely burned patients, which may contribute to their enhanced susceptibility to infection and sepsis.

[Prognostic significance of macroscopic and microscopic findings in acute inhalation damage in the most severely burned patients]

The bronchoscopic examination of the upper respiratory tract is thought to be of major value recognizing and determining the severity of an inhalation injury in burn patients. From clinical observation however it can be questioned if the initial bronchoscopic aspect has indeed any prognostic significance concerning soon or later developing pulmonary complications in those patients. In 15 burn patients with inhalation injury the endoscopically evident lesions of the respiratory tract were classified and documented by photography. Additionally bronchus biopsies for histological examination were taken from different levels of the bronchus tree and a bronchoalveolar lavage (BAL) was performed to gather lung cells of peripheral lung areas. Summarizing the results no firm relations between macroscopically classified degrees of respiratory damage and histopathological diagnosed destructions were found; patients, however, whose differentiation of BAL cells showed an extreme neutrophilia developed progressive lung insufficiency (ARDS) a few days later.

Induction of inflammatory mediators (histamine and leukotrienes) from rat peritoneal mast cells and human granulocytes by Pseudomonas aeruginosa strains from burn patients

Clinical isolates of Pseudomonas aeruginosa from severely burned patients were analyzed with regard to their capacity to induce inflammatory-mediator release from rat mast cells or human granulocytes. The bacterial strains were characterized according to their cell-associated hemolysin activity as well as their secreted hemolysin and phospholipase C activities. P. aeruginosa expressing heat-labile hemolysin and phospholipase C induced histamine release from rat mast cells and leukotriene formation from human granulocytes, while bacterial strains expressing heat-stable hemolysin were potent releasers of histamine but did not lead to leukotriene formation. The mediator-inducing capacity was dependent on the growth characteristics of the bacterial strains. The purified glycolipid (heat-stable hemolysin) of P. aeruginosa was a potent inducer of histamine release but did not initiate leukotriene formation. Exotoxin A did not affect inflammatory-mediator release. P. aeruginosa with leukotriene-inducing capacity also enhanced omega oxidation of endogenous leukotriene B4, suggesting an additional inactivation of the chemotactic potential. Our data suggest that both hemolysins of P. aeruginosa contribute to the pathogenicity of P. aeruginosa by inducing and modulating inflammatory-mediator release from various cells.

[In vitro virulence of wound infecting staphylococcal isolates from severely burned patients]

The hemolysin and histamine releasing activity of 30 S. aureus strains isolated from third degree burns of heavily burned patients was detected. The culture supernatants (cs) of Staphylococcus aureus isolated during episodes of invasive burn wound infection displayed significantly lower amounts of hemolysin and histamine releasing activity as compared to cs of bacteria isolated when no sign of septicemia was present. In contrast, when washed bacterial cells were analysed, a reversed ratio could be observed. These data clearly indicate that in strains isolated during invasive burn wound infection pathogenicity factors remain attached to the bacterial surface of the staphylococci investigated.

Studies on the mechanisms of granulocyte dysfunctions in severely burned patients--evidence for altered leukotriene generation

The leukotriene generation (LTB4, 20-OH-LTB4, 20-COOH-LTB4) from PMNs of severely burned patients (n = 6) was studied by reversed-phase HPLC. Granulocytes from all patients showed a decrease in leukotriene generation which only returned to normal levels when the patients recovered from their injuries. The leukotriene generation induced by different stimuli, i.e., the Ca++-ionophore A23187 (7.3 microM) or opsonized zymosan (2 mg) in the presence of exogenous arachidonic acid (60 microM) showed similar stimulation profiles. The cellular differentiation of the respective granulocyte fractions revealed that the decreased leukotriene generation was accompanied by the occurrence of immature granulocytes in the peripheral blood. Furthermore, the studies in the presence of exogenous arachidonic acid showed that the defect in leukotriene generation from granulocytes of surviving patients was due to the availability of metabolizable substrate (i.e., free arachidonic acid). Granulocytes from one nonsurviving patient showed in addition a defect in the metabolic ability of arachidonic acid to generate the respective leukotrienes. The generation of reactive oxygen species did not correlate with the observed alterations in the formation of the leukotrienes.

Decreased expression of leukotriene B4 receptor sites on polymorphonuclear granulocytes of severely burned patients

Polymorphonuclear granulocytes were isolated from patients with burn injury and the specific binding of (3H)leukotriene B4 was assessed. We observed a decreased receptor expression as compared to healthy donor cells, which may be the result of receptor downregulation as a consequence of cellular preactivation. In addition, leukotriene B4-synthesis was also reduced and differential cell counts demonstrated a shift from segmented neutrophils to immature cells. In survivors the values returned to normal parameters whereas nonsurvivors who succumbed in the course of generalized sepsis showed depressed cellular functions up to their death.

Generation of leukotrienes from human polymorphonuclear granulocytes of severely burned patients

The Ca ionophore A23187-induced leukotriene (LT) release (LTC4, LTB4, 20-OH-LTB4, 20-COOH-LTB4) of human PMN's from severely burned patients (n = 6) was studied by reversed-phase HPLC. The patients' granulocytes demonstrated a decrease (to zero levels) in LT generation postburn. The level of generated LT's resembled that of healthy donors when the patients recovered from their trauma (after day 40 postburn). In contrast, the granulocytes of patients who finally succumbed to their injuries showed poor responsiveness over the total time. An enhanced LTC4 production by granulocytes correlated with an increase in eosinophils within the granulocyte fraction. In addition, the reduced LTB4 production was accompanied by an enhanced LTB4 metabolism to biologically less active products (omega-oxidated metabolites). Thus, the capacity of patients' PMN's to release chemotactic substances was further decreased. The onset of this PMN dysfunction correlated with the onset of invasive microbial growth as determined by the quantitative bacterial analysis of full-thickness biopsy specimens. Our data provide evidence that the altered mediator release of patients' PMN's is closely related to a depressed host defense.

[Comparison of 4 methods of bacterial count determination in burn wounds]

The present study includes twelve patients with second and third degree fresh burns involving 10-70 per cent total body surface area. Standardized surface swab, gaze pad contact, Rodac plates, and burn wound biopsy cultures were obtained twice per week. The various techniques were compared by 48 independent measurements. Confluent growth occur in more than 70 per cent of the Rodac agar plates. There was a significant (alpha less than 1%) correlation between the results of the surface swab and the gaze pad method. A comparison of the number of viable bacteria detected with the burn wound biopsy technique and the surface methods (gaze pad and surface swab) showed no significant correlation. In addition, the number of colony forming units in 8 parallel cultures obtained from different sites of the burn wound was determined. The standard error of mean (SEM) varied between 1.01 log (biopsy), 0.91 log (gaze pad) and 0.61 log (surface swab). Several case reports emphasize that the quantitative biopsy culture seems to give most reliable data in predicting burn wound sepsis.

[Epidemiologic studies of the microbial colonization of severely burned patients]

Bacteria isolated between 1/1/1983 and 12/31/1984 from the burns of 122 patients in a burns unit at the Ruhr-Universität Bochum were studied. Grampositive bacteria were predominant in colonizing the burn wounds (62.5% of all strains isolated). In the patients with more than 40% of total body surface area (TBSA) burn, isolation of Staph aureus was most frequent. The exogenous colonization rate with Staph. aureus was 86%. Coagulase negative Staphylococci were identified in 89.6% of all patients (71.4% of the patients with more than 40% TBSA burn). There was a constant decline in detecting Pseudomonas aeruginosa from the second half of 1983. Microbial sensitivity testing was performed in 834 cases. Gramnegative strains of bacteria resistant to Ampicillin, Mezlocillin, Piperacillin and Ticarcillin were found in 10 up to 97% of the tested strains. Acinetobacter calcoaceticus var. antitratus and Enterobacter cloacae usually displayed a wide resistant pattern. Some strains were resistant as to 16 antibiotics. The incidence of multiresistant Staph. aureus was studied. The time course of multiresistance was paralleled by the incidence of a 6-fold resistance to Benzylpenicillin, Oxacillin, Tetracyclin(T), Gentamycin(G), Erythromycin(E), and Sulfadiacin(S). The probability of simultaneous resistance to 2 of the 4 antibiotics (T, G, E, S) ranged between 0.7 and 0.98. 98 out of 336 Staph. aureus isolates showed a simultaneous resistance to T, G, E and S (29%).

[Late results of 1,046 breast reduction-plasties]

Between 1971 and 1985 1046 reduction mammaplasties were performed using the Strömbeck technique with personal modifications and also subtotal amputations with free nipple grafting were carried out in 162 cases. Late results of these patients show in detail the age, the amount of weight resected, the histology and the complications.

[Facial burns]

Deep partial and full thickness facial burns require early skin grafting. Pressure face masks and local steroids reduce hypertrophic scarring. Split skin and Z-plasties are used for early reconstructive surgery. Only after softening of the scar tissue definite reconstructive work should be undertaken. For this period full thickness skin grafts and local flaps are preferred. Special regional problems require skilled plastic surgery. Reconstructive surgery is the most essential part of the rehabilitation of severe facial burns.

[Hematologic and dermatologic side-effects of antibiotic therapy]

The report details possible haematological and dermatological side effects due to co-trimoxazole: agranulocytosis and epidermiolysis bullosa (Lyell) respectively developed after short-term therapy with co-trimoxazole in two women treated for tonsillitis and acute relapse of chronic obstructive bronchitis respectively. The clinical findings, therapeutical management and clinical outcome of both patients are described. Reviewing the literature the relevance of co-trimoxazole induced side effects is discussed.

[Permanent closure of radioulcers of the lower abdomen and groin region by abdominal dermolipectomy with displacement plastic surgery]

Despite improved techniques in modern x-ray therapy of genital tumors, radioulcera of the groin and lower abdominal wall are still common. The reconstruction of this area can be achieved by a modified abdominoplasty technique. This technique is described and results are demonstrated.

[In-vitro efficacy of topical antibiotics on bacteria from burns]

The influence of topical antimicrobial agents on bacterial growth was determined with an agar diffusion technique. 349 isolates were tested with mafenide acetate and silver sulfadiazine, 226 isolates were tested with povidone iodine. None of these agents was likewise effective against all organisms of the same bacterial strain. The inhibition of growth by mafenide acetate and silver sulfadiazine demonstrated dose-response. 26 to 40% of the tested grampositive cocci were inhibited by mafenide acetate, whereas the growth of about 26 to 90% of gramnegative rods was effected by silver sulfadiazine, with the exception of proteus species (9%). Both agents influenced the growth of pseudomonas (40 to 65%). The results obtained with povidone iodine led to the consideration that the agar diffusion method might not be suitable for testing this drug.

[The effect of burns on the complement system]

Serum levels of total complement CH 50 and the complement components C1, C1 inactivator, C2, C4, C3c, and C3 activator were measured in 20 patients with burn injuries. The findings were assessed for any possible correlations between the results of serological investigations, severity of burns and clinical aspects of the patients.

[Debridement of burns with proteolytic enzymes from Bacillus subtilis]

50 patients with burns received an enzymatic debridement with bacillus subtilis (Protease-ointment = Travase. Symmetrical control sites were treated without Protease-ointment simultaneously. With the help of Protease-ointment early eschar removal was achieved in deep dermal burns. In full thickness burns the success of the treatment was dependent on the depths of the tissue damage and the early application of Protease-ointment, which allowed the removal of the dermal elements of the eschar whereas fat remained unaffected. In our experience Protease-ointment can be considered a valuable method of eschar removal in addition to surgical measures.

[Experience with deep-frozen fresh pig skin in the treatment of 100 burn injury patients]

Our report is based on the treatment of 100 extensive burns with the employment of fresh frozen porcine skin used as biological dressings. Our experience shows that fresh frozen porcine skin equals in most respects non-typed homografts. Its utilization is economical and it is also recommended in cases where the number of human donors is limited.

[Cancellous bone grafting for fingers and metacarpus]

Bone grafting using cancellous bone is a reliable method treating fresh and old fractures. In the period 1974-1977 the Department of Plastic Surgery of the University Hospital "Bergmannsheil Bochum" treated 39 cases of finger- and metacarpal-bone injuries and bone diseases successfully by cancellous bone grafting. Indications, technique and results of our methods are described.

[Primary manifestations of immunoblastic lymphoma in the area of a resected lymphedema]

A patient's trauma in childhood leads to a chronic lymphoedema requiring a Charles' operation in adult life. Eight years following the operation the primary manifestation of a malignant lymphoma is observed within the operated lymphoedema. The aetiology of the tumour remains unknown.

[Problems in intensive care for burns (author's transl)]

Severe burns are followed by a shock period of more than 48 h. Insufficient fluid replacement may lead to serious organic damage. Protein losses are high. Cardio-respiratory complications are frequent. Infection and sepsis are still frequent causes of death. Skin damage requires extensive operations for debridement and skin replacement, and blood losses must be replaced simultaneously.