Merkel Cell Carcinoma - Current Controversies and Future Directions

Merkel cell carcinoma is a rare, aggressive neuroendocrine skin malignancy. Evidence for management comes from case series and single-arm trials. Optimal outcomes require assessment of the patient in a multidisciplinary team setting. Rapid diagnosis and staging are essential for locoregional control and may reduce metastasis. Sentinel lymph node biopsy (SLNB) adds prognostic information. FDG-positron emission tomography has high sensitivity and specificity and affects management in a quarter of cases. Surgical excision and radiotherapy provide good locoregional control even with positive margins. Wide surgical margins are needed if adjuvant radiotherapy is not used. It is uncertain whether adjuvant radiotherapy or elective surgery for uninvolved nodes or for patients selected by positive SLNB improves survival. Total doses of 50 Gy provide high levels of control for microscopic disease but at least 60 Gy should be given for macroscopic disease. Chemotherapy can be given safely with radiotherapy, but the benefit of adjuvant chemotherapy remains uncertain. Trials of adjuvant immune therapy are underway. Unresectable primaries might be controlled with radiotherapy alone or combination systemic therapy, radiotherapy and surgery. Metastatic disease often responds to chemotherapy, but the response duration can be short. Immunity is central to disease control. Immune checkpoint inhibitor treatment resulted in high response rates in chemotherapy-naive patients and lower rates in chemotherapy-refractory patients. Durable responses are observed.

Multisite randomised controlled trial to evaluate polypropylene clips applied to the breech of lambs as an alternative to mulesing. I: effects on body weight, breech bare area measurements and scores, wrinkle scores and faecal and urine staining

OBJECTIVE

 To assess the effects of application of occlusive polypropylene clips to lambs on body weight, breech bare area measurements and scores, wrinkle scores, and faecal and urine stain scores.

PROCEDURES

 A randomised controlled trial using 32,028 lambs was conducted on 208 properties across Australia. Polypropylene clips were applied at lamb marking. At each site, 160 lambs were weighed, measured for breech bare area and scored for bare area, wrinkle, dag and urine staining, and skin type and thickness. Lambs were allocated to a control (no clips) or treatment (breech and tail clips) group. Lambs were assessed on days 14 (range 10-19) and 55 (range 34-129) after clip application for body weight, breech bare area measurements and scores. On day 55 the operators also scored wrinkling and urine staining.

RESULTS

 At an average of 55 days after treatment, treated ewe and wether lambs had 16% and 21% greater horizontal bare area measurements, and 31.7% and 32.7% higher bare area scores than control lambs, respectively. The ewes and wether lambs also had lower wrinkle (6.8% and 5.8%, respectively) and dag scores (12% and 12.3%, respectively) than controls. Treated ewes had lower urine stain scores (18.8%) than controls. However, body weight was slightly lower in clip-treated lambs compared with controls by 0.320 kg (1.2%) and 0.430 kg (1.6%) for ewes and wethers, respectively.

CONCLUSION

 Polypropylene clips applied to the breech and tail of lambs increased breech bare area and reduced dag, urine and wrinkle scores. Improvements in these measures of factors that predispose to blowfly strike suggest that the application of clips may reduce the risk of breech flystrike.

Exploring the role of environmental variables in shaping patterns of seabed biodiversity composition in regional-scale ecosystems

1. Environmental variables are often used as indirect surrogates for mapping biodiversity because species survey data are scant at regional scales, especially in the marine realm. However, environmental variables are measured on arbitrary scales unlikely to have simple, direct relationships with biological patterns. Instead, biodiversity may respond nonlinearly and to interactions between environmental variables.

2. To investigate the role of the environment in driving patterns of biodiversity composition in large marine regions, we collated multiple biological survey and environmental data sets from tropical NE Australia, the deep Gulf of Mexico and the temperate Gulf of Maine. We then quantified the shape and magnitude of multispecies responses along >30 environmental gradients and the extent to which these variables predicted regional distributions. To do this, we applied a new statistical approach, Gradient Forest, an extension of Random Forest, capable of modelling nonlinear and threshold responses.

3. The regional‐scale environmental variables predicted an average of 13–35% (up to 50–85% for individual species) of the variation in species abundance distributions. Important predictors differed among regions and biota and included depth, salinity, temperature, sediment composition and current stress. The shapes of responses along gradients also differed and were nonlinear, often with thresholds indicative of step changes in composition. These differing regional responses were partly due to differing environmental indicators of bioregional boundaries and, given the results to date, may indicate limited scope for extrapolating bio‐physical relationships beyond the region of source data sets.

4.  Synthesis and applications. Gradient Forest offers a new capability for exploring relationships between biodiversity and environmental gradients, generating new information on multispecies responses at a detail not available previously. Importantly, given the scarcity of data, Gradient Forest enables the combined use of information from disparate data sets. The gradient response curves provide biologically informed transformations of environmental layers to predict and map expected patterns of biodiversity composition that represent sampled composition better than uninformed variables. The approach can be applied to support marine spatial planning and management and has similar applicability in terrestrial realms.

Gradient Forest offers a new capability for exploring relationships between biodiversity and environmental gradients, generating new information on multispecies responses at a detail not available previously. Importantly, given the scarcity of data, Gradient Forest enables the combined use of information from disparate data sets. The gradient response curves provide biologically informed transformations of environmental layers to predict and map expected patterns of biodiversity composition that represent sampled composition better than uninformed variables. The approach can be applied to support marine spatial planning and management and has similar applicability in terrestrial realms.

Spatial scale of similarity as an indicator of metacommunity stability in exploited marine systems

The spatial scale of similarity among fish communities is characteristically large in temperate marine systems: connectivity is enhanced by high rates of dispersal during the larval/juvenile stages and the increased mobility of large-bodied fish. A larger spatial scale of similarity (low beta diversity) is advantageous in heavily exploited systems because locally depleted populations are more likely to be "rescued" by neighboring areas. We explored whether the spatial scale of similarity changed from 1970 to 2006 due to overfishing of dominant, large-bodied groundfish across a 300 000-km2 region of the Northwest Atlantic. Annually, similarities among communities decayed slowly with increasing geographic distance in this open system, but through time the decorrelation distance declined by 33%, concomitant with widespread reductions in biomass, body size, and community evenness. The decline in connectivity stemmed from an erosion of community similarity among local subregions separated by distances as small as 100 km. Larger fish, of the same species, contribute proportionally more viable offspring, so observed body size reductions will have affected maternal output. The cumulative effect of nonlinear maternal influences on egg/larval quality may have compromised the spatial scale of effective larval dispersal, which may account for the delayed recovery of certain member species. Our study adds strong support for using the spatial scale of similarity as an indicator of metacommunity stability both to understand the spatial impacts of exploitation and to refine how spatial structure is used in management plans.

Thrombotic microangiopathy from Australian brown snake (Pseudonaja) envenoming

BACKGROUND

Australian brown snake (genus Pseudonaja) envenoming causes a venom-induced consumptive coagulopathy (VICC). A proportion of cases go on to develop thrombotic microangiopathy characterized by thrombocytopenia, microangiopathic haemolytic anaemia (MAHA) and acute renal failure (ARF).

AIM

The aim of the study was to define better the natural history and empirical treatments for thrombotic microangiopathy in brown snake envenoming.

METHODS

A review of brown snake bites recruited to the Australian Snakebite Project (ASP), a national multicentre study of snake envenoming was undertaken. Serial data are recorded on clinical effects and laboratory results, including measurement of venom concentrations. We describe cases of thrombotic microangiopathy and compare these to cases without thrombotic microangiopathy.

RESULTS

From 32 cases of brown snake envenoming with severe VICC, four (13%) developed thrombotic microangiopathy, we also included two cases of thrombotic microangiopathy from prior to ASP. All six developed severe thrombocytopenia (<20 x 10(-9)/L), worst 3 days after the bite and resolving over a week, MAHA with fragmented red blood cells on the blood film and five developed anuric ARF requiring dialysis and lasting 2-8 weeks. All six received antivenom, which was delayed compared with other brown snake-envenoming cases. Four were treated with plasmapheresis. The severity and recovery of the thrombocytopenia, anaemia and renal function were similar with and without plasmapheresis. The median length of stay for MAHA cases was 14 days (interquartile range (IQR) 12-14) compared to 1.8 days (IQR 1.3-2) for all other cases.

CONCLUSION

Thrombotic microangiopathy resulting from brown snake bite appears to have a good prognosis and management should focus on early antivenom therapy and supportive care including dialysis. The role of plasmapheresis is yet to be defined.

High dose chemotherapy and autologous stem cell transplantation as adjuvant therapy for primary breast cancer patients with four or more lymph nodes involved: long-term results of an international randomised trial

BACKGROUND

The purpose of this study was to assess whether a short course of anthracycline containing chemotherapy followed by high dose therapy with autologous stem-cell support improves disease-free and overall survival as compared with conventional, anthracycline containing chemotherapy, in patients with primary breast cancer and four or more histologically involved lymph nodes.

PATIENTS AND METHODS

Two hundred and eighty one patients entered into a randomised clinical trial were allocated to receive standard, conventional treatment (5-fluorouracil, epirubicin and cyclophosphamide-FEC for six cycles) or FEC for three cycles followed by high dose therapy consisting of cyclophosphamide, thiotepa and carboplatin and stem cell rescue (HDT). To be eligible, patients had to be free of overt metastatic disease and be < or =60 years of age. Analyses were according to intention to treat.

RESULTS

At a median follow up of 68 months, 118 patients have experienced a relapse or death from breast cancer (62 in the FEC followed by HDT arm and 56 in the conventional FEC arm) and a total of 100 patients have died (54 in the FEC followed by HDT arm and 46 in the conventional FEC arm). No significant difference was observed in relapse-free survival [hazard ratio 1.06, 95% CI 0.74-1.52, p = 0.76] or overall survival [hazard ratio 1.18, 95% CI 0.80-1.75, p = 0.40]. Five patients died from treatment related causes, three as a consequence of HDT and two in the conventional FEC arm.

CONCLUSIONS

At the present time, no benefit has been observed from replacing three cycles of conventional chemotherapy with the HDT regimen described here. Patients should continue to receive conventional chemotherapy as adjuvant therapy for breast cancer.

In vitro effects of isoprinosine and a dipeptide methyl ester on Echinococcus multilocularis protoscoleces

A protoscoleces/vesicles in vitro maintenance test with assessment of viability by eosin exclusion was used to evaluate the quantitative and qualitative activities of isoprinosine, its active component inosine and the dipeptide methylester L-Phe-Phe-OMe on isolated protoscoleces of Echinococcus multilocularis for 24 and 48 h. Isoprinosine and inosine showed dose- and time-dependent activity, the latter displaying a more rapid effect than the former. A high activity was shown with L-Phe-Phe-OMe, when compared to praziquantel. Ultrastructural alterations were much more striking with L-Phe-Phe-OMe, with an effect similar to that of praziquantel, whereas the chemotherapeutic activity of inosine and isoprinosine appeared to be directed against a metabolic target, with a lethal effect not immediately visible at the ultrastructural level. Thus, the previously reported in vivo activities of these drugs result largely from a direct effect on the parasite.

Echinococcus multilocularis alkaline phosphatase as a marker for metacestode damage induced by in vitro drug treatment with albendazole sulfoxide and albendazole sulfone

Alveolar echinococcosis (AE) is caused by the metacestode stage of the fox tapeworm Echinococcus multilocularis. The disease affects the human liver and occasionally other organs and is fatal if treatment is unsuccessful. The present chemotherapy of AE is based on the administration of benzimidazole carbamate derivatives, such as mebendazole and albendazole. Albendazole treatment has been found to be ineffective in some cases, parasitostatic rather than parasiticidal, and the recurrence rate is rather high. Therefore, chemotherapy usually involves the lifelong uptake of massive doses of albendazole and new treatment options are urgently needed. In order to avoid costly and time-consuming animal experimentation, a first step in searching for novel parasiticidal compounds could be the in vitro drug screening of novel compounds by employing metacestode cultivation. However, presently used techniques (e.g., transmission electron microscopy) for determination of parasite viability involve costly equipment and time-consuming preparation of rather large amounts of parasite material. We therefore searched for a parasite marker which can be easily traced and the presence or absence of which is indicative of parasite viability. In this study we show that the increase of E. multilocularis alkaline phosphatase activity in culture supernatants during in vitro drug treatment with albendazole derivatives correlates with the progressive degeneration and destruction of the metacestode tissue. The inexpensive and rapid assay presented here will serve as an ideal tool for performing first-round in vitro tests on the efficacy of a large number of antiparasitic compounds.

Use of Percoll for the infection of cells in vitro with Cryptosporidium parvum oocysts

A method for the infection of non-adherent THP-1 cells and adherent MDBK cells with Cryptosporidium parvum oocysts using isotonic Percoll solutions was developed. Excystation was maximal after 2 h, but toxicity increased with the oocyst/cell ratio and the incubation time. The infection rates did not increase with the oocyst/cell ratio and both cell types were equally parasitized.

Electroconvulsive therapy is associated with superior symptomatic and functional change in depressed patients after psychiatric hospitalization

BACKGROUND

Major depressive episode is associated with quality of life (QOL) deficits, and QOL improves following remission of depression. We conducted an observational study of the relationship between depressive symptoms and QOL for 1 year after psychiatric hospitalization, and compared QOL in patients who received ECT against those who did not.

METHODS

We examined 88 patients with major depressive disorder (53.4+/-15.4 years old; 69 women) upon admission, with repeated measurements at discharge, 1, 3, 6, and 12 months after discharge. Depression severity was measured with the Beck Depression Inventory. QOL measurements encompassed ADLs, IADLs, performance in major roles, and satisfaction with relationships. Treatment for depression was at the discretion of the respective physicians.

RESULTS

Depression severity dropped dramatically by discharge, and changed little thereafter. QOL measures showed improvement at the first month, with additional improvement at the third month. Improvement in QOL was closely tied to improvement in depression severity. ECT during the index hospitalization was associated with greater improvement in depressive symptoms and in most measures of QOL.

LIMITATIONS

The results of this study may not apply to the treatment of outpatients, and the large number of statistical comparisons may have resulted in some spurious associations.

CONCLUSIONS

Inpatient treatment of depression is followed by improvement in QOL. Novel findings in this study include evidence that maximum improvement in QOL does not occur until an average of 3 months after discharge, and that ECT-treated patients had superior outcomes.

Mice transgenic for BAFF develop lymphocytic disorders along with autoimmune manifestations

The cause of many autoimmune and inflammatory diseases is unresolved, although dysregulated production of tumor necrosis factor (TNF) family members appears to be important in many cases. BAFF, a new member of the TNF family, binds to B cells and costimulates their growth in vitro. Mice transgenic for BAFF have vastly increased numbers of mature B and effector T cells, and develop autoimmune-like manifestations such as the presence of high levels of rheumatoid factors, circulating immune complexes, anti-DNA autoantibodies, and immunoglobulin deposition in the kidneys. This phenotype is reminiscent of certain human autoimmune disorders and suggests that dysregulation of BAFF expression may be a critical element in the chain of events leading to autoimmunity.

Effects of mood and age on quality of life in depressed inpatients

BACKGROUND

Prior investigations have demonstrated a link between quality of life (QOL) deficits and depression. This report elaborates on prior investigations findings by implementation of formal assignment of the diagnosis of depression and a hierarchical approach to assessment of QOL.

METHODS

A masters or doctoral level mental health clinician used the SCID to confirm a diagnosis of major depression in ninety psychiatric inpatients. Function was assessed with the PSMS (a measure of ADL), the IADL scale, and the "daily living and role functioning" and the "relation to self and others" subscales of the Basis-32.

RESULTS

Patient age and severity of depression were the most consistent predictors of QOL deficits, although the direction of the age-effect on QOL depended on the specific measure of QOL. Increasing severity of depression was consistently associated with worse QOL, and remained significant after adjusting for age.

LIMITATIONS

The cross-sectional method of this study limits the inference of causality between depression severity and poor QOL.

CONCLUSIONS

QOL deficits in acutely depressed hospitalized patients occur at multiple strata in the hierarchy of behavior and are most consistently influenced by age and severity of depression. The effect of age on QOL in depressed inpatients is complex, and age is not uniformly associated with poor QOL.

Pretreatment differences in specific symptoms and quality of life among depressed inpatients who do and do not receive electroconvulsive therapy: a hypothesis regarding why the elderly are more likely to receive ECT

Electroconvulsive therapy (ECT) is among the most commonly performed medical procedures requiring general anesthesia in the United States. Nevertheless, very little is known about the characteristics of depressed patients who receive ECT and how they differ from depressed patients receiving psychotropic medication. We conducted a detailed examination of demographic, clinical, and quality-of-life (QOL) measurements in a group of 90 depressed inpatients, and we then used these measurements to contrast the 31 patients who received ECT with the 59 who received alternative therapies. The ECT group did not differ from the non-ECT group in gender composition, marital status, race, education, employment status, overall severity of depression, chronicity of depression, adequacy of prehospitalization antidepressant treatment, extent of physical illness, or extent of social support. The ECT group was older. Furthermore, the ECT group had greater weight loss, worse functioning in activities of daily living (ADLs), and worse functioning in instrumental activities of daily living (IADLs). The differences in weight loss, ADL, and IADL scores disappeared after age adjustment. However, statistical adjustment for age revealed that the ECT group reported worse capacity in their daily living and role functioning than did the non-ECT group. We conclude that the decision to pursue ECT is based in part on the perceived effect of the depression on QOL, as well as the severity of specific symptoms such as weight loss. The elderly seem particularly vulnerable to depression-related functional deficits and weight loss, and this may explain why prior studies showed a differential use of ECT in the elderly.

BAFF, a novel ligand of the tumor necrosis factor family, stimulates B cell growth

Members of the tumor necrosis factor (TNF) family induce pleiotropic biological responses, including cell growth, differentiation, and even death. Here we describe a novel member of the TNF family, designated BAFF (for B cell activating factor belonging to the TNF family), which is expressed by T cells and dendritic cells. Human BAFF was mapped to chromosome 13q32-34. Membrane-bound BAFF was processed and secreted through the action of a protease whose specificity matches that of the furin family of proprotein convertases. The expression of BAFF receptor appeared to be restricted to B cells. Both membrane-bound and soluble BAFF induced proliferation of anti-immunoglobulin M-stimulated peripheral blood B lymphocytes. Moreover, increased amounts of immunoglobulins were found in supernatants of germinal center-like B cells costimulated with BAFF. These results suggest that BAFF plays an important role as costimulator of B cell proliferation and function.

Both the lymphotoxin and tumor necrosis factor pathways are involved in experimental murine models of colitis

BACKGROUND & AIMS

Membrane lymphotoxin (LT) alpha/beta, a member of the tumor necrosis factor (TNF) family of immune regulatory molecules, is involved both in the development of secondary lymphoid tissues and the maintenance of organized lymphoid tissues in the adult. Defects observed in the mucosal immune system in animals with a genetically disrupted LTalpha/beta pathway coupled with the expression of LTalpha/beta in activated T cells motivated an examination of the importance of this pathway in experimental colitis.

METHODS

Soluble LTbeta receptor (LTbetaR) immunoglobulin fusion protein was used to inhibit the LTalpha/beta/light axis in two independent rodent models of colitis: CD45RBhi CD4(+)-reconstituted SCID mice and bone marrow-transplanted tg26 mice (BM --> tg26).

RESULTS

Treatment with LTbetaR immunoglobulin attenuated the development of both the clinical and histological manifestations of the disease in these two murine models of colitis. Given the success of TNF inhibitors in the treatment of human Crohn's disease, the effects of LTbetaR immunoglobulin have been compared with antibody to TNF in the BM --> tg26 model, and both treatments were equally efficacious.

CONCLUSIONS

The LT pathway plays a role in the development of colitis as important as that of the TNF system and, therefore, represents a potential novel intervention point for the treatment of inflammatory bowel disease.

Feeding response of the dendrochirote sea cucumber Cucumaria frondosa (Echinodermata: Holothuroidea) to changing food concentrations in the laboratory

Sea cucumbers (Cucumaria frondosa) (Echinodermata: Holothuroidea) held in flow-through tanks were exposed to different chloropigment concentrations by manipulating the seston concentration via the use of water filters in the inflow lines and the addition of cultured algae or natural plankton to tanks. The percentage of sea cucumbers open and feeding increased asymptotically as the seston chloropigment concentration increased. Below 50 µg·L-1 the percentage of sea cucumbers with tentacles extended and feeding decreased. The rate at which sea cucumbers inserted their tentacles into their mouths (0.96 ± 0.34 insertion/min (mean ± SD)) increased with increasing seston quality. Cucumaria frondosa fed at faster rates at the higher concentrations. There was a significant positive relationship between the stomach content (amount of chloropigment) of sea cucumbers and the seston chloropigment concentration to which they were exposed (r2 = 0.200, p < 0.001).

Alterations of Toxoplasma gondii induced by 2',3'-dideoxyinosine in vitro

The time-course of action of the antiviral agent 2',3'-dideoxyinosine (ddI) against Toxoplasma gondii tachyzoites in vitro and its effects at the ultrastructural level were investigated. The very short latency of effect and high efficacy of ddI were evidenced by the fact that the drugs' effects on parasite growth occurred 2 hr after addition to the culture medium, and that an IL90 value of 0.5 microg/ml was reached after 72 hr. Although without apparent effect on uninfected cells, ddI clearly acted on the intracellular parasites, which tended to disappear. Remaining tachyzoites were almost exclusively extracellularly located and often exhibited a clustering of mitochondria-like bodies and subsequent deep alterations of their plasma membranes. These results confirm previous findings and emphasize the potential usefulness of ddI in the management of cerebral toxoplasmosis, a major health problem in acquired immune deficiency syndrome patients.

In vitro cultivation of Cryptosporidium parvum in the non-adherent human monocytic THP-1 cell line

This study shows that the human monocytic cell line THP-1 supports the growth of C. parvum. Immunofluorescence controls showed that only scarce oocysts remained after infection and disappeared within the first 24 h of culture. A continuous asexual life cycle proceeded throughout the experiments, with at least 15-d cultures. This model provides a useful tool for studies on the biology of C. parvum in cells involved in its transport in immunocompromised host.

Characterization of lymphotoxin-alpha beta complexes on the surface of mouse lymphocytes

The lymphotoxin-alpha beta complex (LT alpha beta) is found on the surface of activated lymphocytes and binds to a specific receptor called the LT beta receptor (LT beta R). In the mouse, signaling through this pathway is important for lymph node development and splenic organization, yet the biochemical properties of murine LT alpha and LT beta are essentially unknown. Here we have used soluble receptor-Ig forms of LT beta R and TNF-R55 and mAbs specific for murine LT alpha, LT beta, and LT beta R to characterize the appearance of surface LT alpha beta complexes and LT beta R on several common murine cell lines. Cells that bound LT beta R also bound anti-LT alpha and anti-LT beta mAbs in a FACS analysis. The ability of these reagents to discriminate between surface TNF and LT was verified by analysis of surface TNF-positive, LPS-activated murine RAW 264.7 monocytic cells. Primary mouse leukocytes from spleen, thymus, lymph node, and peritoneum were activated in vitro, and CD4+ and CD8+ T cells as well as B cells expressed surface LT ligand but not the LT beta R. Conversely, elicited peritoneal monocytes/macrophages were surface LT negative yet LT beta R positive. This study shows that on mononuclear cells, surface LT complexes and receptor are expressed similarly in mice and man, and the tools described herein form the foundation for study of the functional roles of the LT system in the mouse.

Cytotoxic activities of recombinant soluble murine lymphotoxin-alpha and lymphotoxin-alpha beta complexes

Human lymphotoxin-alpha (LT alpha) is found in a secreted form and on the surface of lymphocytes as a complex with a second related protein called lymphotoxin-beta (LT beta). Both secreted human LT alpha and TNF have similar biological activities mediated via the TNF receptors, whereas the cell surface LT alpha beta complex binds to a separate receptor called the LT beta receptor (LT beta R). The murine LT alpha and LT beta (mLT alpha and mLT beta) proteins have never been characterized. When recombinant mLT alpha was produced by either of several methods, the protein had a very low specific activity relative to that of human LT alpha in the conventional WEHI 164 cytotoxicity bioassay. The weak activity observed was inhibited by a soluble murine TNF-R55 Ig fusion protein (mTNF-R55-Ig), but not by mLT beta R-Ig. Coexpression of both mLT alpha and a soluble version of mLT beta in insect cells led to an LT alpha beta form that was cytotoxic in the WEHI 164 assay via the LT beta R. To determine whether natural mLT alpha-like forms with cytotoxic activity comparable to that of secreted human LT alpha were secreted from primary spleen cells, splenic lymphocytes were activated in various ways, and their supernatants were analyzed for cytotoxic activity. Using specific Abs to distinguish between mTNF and mLT, a TNF component was readily detected; however, there was no evidence for a secreted mLT alpha cytotoxic activity using this assay. Combined, these observations suggest that secreted mLT alpha may not play a role in the mouse via interactions with TNF-R55, and the ramifications of this hypothesis are discussed.

Echinococcus multilocularis metacestodes: immunological and immunocytochemical analysis of the relationships between alkaline phosphatase and the Em2 antigen

Echinococcus multilocularis metacestodes possess an alkaline phosphatase (EmAP) which has been extensively characterized at the biochemical level in previous studies. The apparent molecular weight of the enzyme monomer and its isoelectric point matched those originally described for the Em2 antigen, a reference antigen currently used for the immunodiagnosis of E. multilocularis infection. These observations raised questions about the molecular relationship between the two molecules. In order to investigate the relations between EmAP and the Em2 antigen, immunoblotting and ELISA were carried out using polyclonal and monoclonal antibodies directed against EmAP and the Em2 antigen, respectively. In addition, the localization of EmAP and the Em2 antigen was compared by immunofluorescence and immunogold electron microscopy in in vitro-generated E. multilocularis metacestodes. The results show that common epitopes between EmAP and Em2 exist, which are predominantly of a peptidic nature. Both antigens are localized in an acellular parasite structure, the laminated layer, with additional locations for the EmAP on the glycocalyx and in the central region of invaginated protoscoleces. These results suggest a putative functional relationship between the two antigens and that Em2 could originate from EmAP.

Cytotoxic activities of recombinant soluble murine lymphotoxin-alpha and lymphotoxin-alpha beta complexes

Human lymphotoxin-alpha (LT alpha) is found in a secreted form and on the surface of lymphocytes as a complex with a second related protein called lymphotoxin-beta (LT beta). Both secreted human LT alpha and TNF have similar biological activities mediated via the TNF receptors, whereas the cell surface LT alpha beta complex binds to a separate receptor called the LT beta receptor (LT beta R). The murine LT alpha and LT beta (mLT alpha and mLT beta) proteins have never been characterized. When recombinant mLT alpha was produced by either of several methods, the protein had a very low specific activity relative to that of human LT alpha in the conventional WEHI 164 cytotoxicity bioassay. The weak activity observed was inhibited by a soluble murine TNF-R55 Ig fusion protein (mTNF-R55-Ig), but not by mLT beta R-Ig. Coexpression of both mLT alpha and a soluble version of mLT beta in insect cells led to an LT alpha beta form that was cytotoxic in the WEHI 164 assay via the LT beta R. To determine whether natural mLT alpha-like forms with cytotoxic activity comparable to that of secreted human LT alpha were secreted from primary spleen cells, splenic lymphocytes were activated in various ways, and their supernatants were analyzed for cytotoxic activity. Using specific Abs to distinguish between mTNF and mLT, a TNF component was readily detected; however, there was no evidence for a secreted mLT alpha cytotoxic activity using this assay. Combined, these observations suggest that secreted mLT alpha may not play a role in the mouse via interactions with TNF-R55, and the ramifications of this hypothesis are discussed.

Characterization of lymphotoxin-alpha beta complexes on the surface of mouse lymphocytes

The lymphotoxin-alpha beta complex (LT alpha beta) is found on the surface of activated lymphocytes and binds to a specific receptor called the LT beta receptor (LT beta R). In the mouse, signaling through this pathway is important for lymph node development and splenic organization, yet the biochemical properties of murine LT alpha and LT beta are essentially unknown. Here we have used soluble receptor-Ig forms of LT beta R and TNF-R55 and mAbs specific for murine LT alpha, LT beta, and LT beta R to characterize the appearance of surface LT alpha beta complexes and LT beta R on several common murine cell lines. Cells that bound LT beta R also bound anti-LT alpha and anti-LT beta mAbs in a FACS analysis. The ability of these reagents to discriminate between surface TNF and LT was verified by analysis of surface TNF-positive, LPS-activated murine RAW 264.7 monocytic cells. Primary mouse leukocytes from spleen, thymus, lymph node, and peritoneum were activated in vitro, and CD4+ and CD8+ T cells as well as B cells expressed surface LT ligand but not the LT beta R. Conversely, elicited peritoneal monocytes/macrophages were surface LT negative yet LT beta R positive. This study shows that on mononuclear cells, surface LT complexes and receptor are expressed similarly in mice and man, and the tools described herein form the foundation for study of the functional roles of the LT system in the mouse.

Lymphotoxin but not tumor necrosis factor functions to maintain splenic architecture and humoral responsiveness in adult mice

To compare the function of the tumor necrosis factor (TNF) and lymphotoxin (LT)alpha/beta systems in the mature immune system, these two pathways were blocked with soluble receptor-immunoglobulin (R-Ig) fusion proteins in normal adult mice. Inhibition of LT alpha/beta signaling using LT betaR-Ig or a blocking monoclonal antibody against murine LT beta had profound effects. The spleen lacked discrete B cell follicles and the marginal zone was altered. Less marked changes were detected in lymph nodes. LT alpha/beta inhibition also prevented germinal center formation in the spleen and impaired Ig production in response to sheep red blood cells (SRBC) immunization. These results show that the LT alpha/beta system is required for the maintenance of splenic architecture and normal immune responses, and not simply for the development of peripheral immune organs during ontogeny. In contrast, inhibition of the TNF/LT alpha pathway with TNF-R55-Ig did not affect the splenic architecture or the anti-SRBC response. Splenic defects and impaired antibody responses are seen in TNF-deficient mice, suggesting that TNF is important during development. Therefore relative to TNF, the LT system has the dominant influence on splenic organization and anti-SRBC Ig formation in the adult mouse.

Effects of 2',3'-dideoxyinosine on Toxoplasma gondii cysts in mice

The activity against Toxoplasma gondii of 2',3' dideoxyinosine (ddI), an anti-human immunodeficiency virus drug, was examined in an in vitro and in vivo study. Cell cultures infected with a strain known to cause chronic infections were used to show the dose-dependent effect of this drug compared with spiramycin and sulfadiazine. When a dose of 4 microg/ml was used, no infected THP-1 cells or parasites were found after 60 h of incubation. An electron-microscopic study confirmed that after 12 h at 1 microg/ml, the few parasites observed were severely altered. The treatment of chronically infected mice 3 months postinfection showed that a 30-day treatment with 2 mg of ddI/ml induced a significant reduction in the number of T. gondii cysts in the cerebral tissue. These cysts were not viable, as confirmed by immunofluorescence and reinfection experiments. These experiments suggest a possible role for ddI in the treatment of toxoplasmosis, and this possibility deserves further investigation.

Distinct roles in lymphoid organogenesis for lymphotoxins alpha and beta revealed in lymphotoxin beta-deficient mice

Lymphotoxin alpha (LT alpha)-deficient mice revealed critical roles for LT alpha in lymphoid organogenesis, but it is not clear whether LT alpha functions through an LT alpha homotrimer (LT alpha3) or LT alpha/beta heterotrimers. We generated LTbeta-deficient mice and found them to lack Peyer's patches, peripheral lymph nodes, splenic germinal centers, and follicular dendritic cells. Unlike LT alpha-deficient mice, LT beta-deficient mice had cervical and mesenteric lymph nodes. Furthermore, the mesenteric lymph nodes had germinal center-like regions, although these structures appeared to lack follicular dendritic cells. The absence of cervical and mesenteric lymph nodes in LT alpha-deficient mice, and yet their presence in LT beta-deficient mice and in mice deficient in tumor necrosis factor receptor types I and II, suggest that LT alpha3 may signal via an as yet unidentified receptor.

Antibodies against Echinococcus multilocularis alkaline phosphatase as markers for the specific diagnosis and the serological monitoring of alveolar echinococcosis

The immunological properties of the purified alkaline phosphatase (pAP) of Echinococcus multilocularis metacestodes have been investigated using alveolar echinococcosis (AE) patient sera in ELISA tests. A comparative study was done with EmC-Ag (crude antigen) and pAP-Ag (purified antigen). When the parasite purified enzyme pAP was used as antigen, the specificity of the ELISA was markedly increased since it reached 100% without any decrease of its sensitivity (100%). The serologic follow-up of AE patients was conducted during several months with these two antigens in three categories of patients: cured, stabilized and aggravated. There was a good correlation between clinical and serologic data when the pAP was used as antigen in ELISA tests. The anti-pAP antibodies titres did change more rapidly than anti-EmC antibodies titres when a recurrence occurred. Modifications of the anti-pAP antibodies levels were also observed during the patient's therapy: mebendazole, albendazole and Isoprinosine. These results suggest that pAP-Ag should be used for the diagnosis and the follow-up of AE patients.

Echinococcus granulosus, E. multilocularis and mammalian liver-type alkaline phosphatases: a comparative study

The alkaline phosphatases (EC 3.1.3.1) from Echinococcus granulosus and E. multilocularis (Cestoda) were compared to each other and to a liver-type enzyme. The purified proteins (210 and 220 kDa, respectively) had a tetrameric structure composed of 4, 56/53 kDa subunits. Enzymatic removal of their N-linked sugar moieties abolished the differences in their apparent molecular weight under reducing conditions. After phase separation in Triton X-114, the E. multilocularis enzyme was the most amphiphilic, and treatment with PI-P1C reduced the amount of the parasite alkaline phosphatases that were in a hydrophobic form by about 50%. Both parasite enzymes were highly resistant to heat denaturation and insensitive to the inhibitors L-phenylalanine and L-leucine. In addition, L-homoarginine, levamisole and ZnCl2 can be used to differentiate the parasite and mammalian liver-type enzymes from each other. The Echinococcus alkaline phosphatases have original biochemical properties when compared to the mammalian liver-type enzyme.

Characterization of the mouse lymphotoxin-beta gene

Lymphotoxin-beta (LT-beta) is a member of the TNF family of ligands which when expressed with lymphotoxin-alpha (LT-alpha, i.e., the original LT or TNF-beta) forms a heteromeric complex with LT-alpha on the cell surface. The mouse gene structure was determined by both cDNA cloning and analysis of a genomic DNA fragment encompassing the TNF/LT locus in the H-2 region of chromosome 17. The mouse and human genomic structures were found to be similar in terms of location in the class III region of the MHC; however, the mouse gene lacks one intron found in most members of the family. Both the cDNA and the genomic sequences revealed an altered splice donor in the conventional intron 2 position, rendering it nonfunctional. The altered gene retains an open reading frame such that an additional 66 amino acids are inserted into the stalk region connecting the transmembrane domain with the receptor binding domain encoded by exon 4 in this type II membrane protein. Northern analysis showed that this gene is expressed predominantly in lymphoid organs. The outlining of the complete mouse TNF locus will further studies of the relationship between these genes and immune function.

Characterization of the mouse lymphotoxin-beta gene

Lymphotoxin-beta (LT-beta) is a member of the TNF family of ligands which when expressed with lymphotoxin-alpha (LT-alpha, i.e., the original LT or TNF-beta) forms a heteromeric complex with LT-alpha on the cell surface. The mouse gene structure was determined by both cDNA cloning and analysis of a genomic DNA fragment encompassing the TNF/LT locus in the H-2 region of chromosome 17. The mouse and human genomic structures were found to be similar in terms of location in the class III region of the MHC; however, the mouse gene lacks one intron found in most members of the family. Both the cDNA and the genomic sequences revealed an altered splice donor in the conventional intron 2 position, rendering it nonfunctional. The altered gene retains an open reading frame such that an additional 66 amino acids are inserted into the stalk region connecting the transmembrane domain with the receptor binding domain encoded by exon 4 in this type II membrane protein. Northern analysis showed that this gene is expressed predominantly in lymphoid organs. The outlining of the complete mouse TNF locus will further studies of the relationship between these genes and immune function.

Characterization of surface lymphotoxin forms. Use of specific monoclonal antibodies and soluble receptors

Lymphotoxin (LT) is a cytokine related to TNF, found in human systems in both secreted and membrane bound forms. The well characterized secreted form is a trimer of a single protein, LT-alpha, whereas the surface form is composed of a complex between two related molecules, LT-alpha and LT-beta. Because there is a distinct receptor for the complex, the membrane form is believed to signal via events different from those elicited by TNF and secreted LT-alpha. By using a battery of anti-LT-alpha and LT-beta mAbs, it is clear that two LT surface forms exist on the surface of PMA-activated II-23 cells, a human T cell hybridoma. Assuming that these surface forms are trimers, a minor form appears early after induction having an apparent stoichiometry of LT-alpha 2/beta 1 and is recognized by one group of anti-LT-alpha mAbs and the p55-TNF receptor. The second and predominant form has an apparent LT-alpha 1/beta 2 composition and is recognized by a second group of pantrophic anti-LT-alpha mAbs and the LT-beta receptor. Neither of the heteromeric forms nor a putative LT-beta homotrimeric form were found to be secreted. The properties of surface LT on the II-23 cell system were similar to those of the surface LT forms on Chinese hamster ovary cells transfected with both LT-alpha and LT-beta genes and a number of lymphoid tumor lines. These experiments point toward the LT-alpha 1/beta 2 complex as the predominant membrane form of LT on the lymphocyte surface, and this complex is the primary ligand for the LT-beta receptor.

Characterization of surface lymphotoxin forms. Use of specific monoclonal antibodies and soluble receptors

Lymphotoxin (LT) is a cytokine related to TNF, found in human systems in both secreted and membrane bound forms. The well characterized secreted form is a trimer of a single protein, LT-alpha, whereas the surface form is composed of a complex between two related molecules, LT-alpha and LT-beta. Because there is a distinct receptor for the complex, the membrane form is believed to signal via events different from those elicited by TNF and secreted LT-alpha. By using a battery of anti-LT-alpha and LT-beta mAbs, it is clear that two LT surface forms exist on the surface of PMA-activated II-23 cells, a human T cell hybridoma. Assuming that these surface forms are trimers, a minor form appears early after induction having an apparent stoichiometry of LT-alpha 2/beta 1 and is recognized by one group of anti-LT-alpha mAbs and the p55-TNF receptor. The second and predominant form has an apparent LT-alpha 1/beta 2 composition and is recognized by a second group of pantrophic anti-LT-alpha mAbs and the LT-beta receptor. Neither of the heteromeric forms nor a putative LT-beta homotrimeric form were found to be secreted. The properties of surface LT on the II-23 cell system were similar to those of the surface LT forms on Chinese hamster ovary cells transfected with both LT-alpha and LT-beta genes and a number of lymphoid tumor lines. These experiments point toward the LT-alpha 1/beta 2 complex as the predominant membrane form of LT on the lymphocyte surface, and this complex is the primary ligand for the LT-beta receptor.

Purification and characterization of the alkaline phosphatase from Echinococcus granulosus cyst membranes

The purification to homogeneity and the characterization of Echinococcus granulosus alkaline phosphatase (AP; EC 3.1.3.1) from hydatid cyst membranes are described. After n-butanol extraction, the parasite enzyme was sequentially purified by affinity chromatography on concanavalin A-sepharose followed by gel filtration. The purified protein (210 kDa) had a tetrameric structure composed of 4 56-kDa subunits. Its isoelectric point (4.8) and its kinetic parameters were determined (Km = 0.24 +/- 0.05 mmol/L; Vm = 173 +/- 21 nmol/min/mg protein for p-nitrophenylphosphate). The parasite enzyme differed from the host liver enzyme in its thermal stability, optimum reaction temperature, optimum pH, and catalytic parameters, but not in its apparent molecular weight. Furthermore, sera from patients infected with E. granulosus recognized the parasite AP on immunoblots, whereas uninfected controls were negative. These results as well as the role of this enzyme in the host-parasite relationship emphasize its potential importance as a diagnostic and prognostic antigen in the monitoring of hydatid infection.

Are events after endotoxemia related to circulating phospholipase A2?

OBJECTIVE

The authors sought to determine whether the signs and symptoms of endotoxemia were related to the endotoxin-stimulated increase in circulating phospholipase A2 (PLA2) activity.

BACKGROUND

Because hypotension and pulmonary injury have been associated with elevated PLA2 activity in septic shock and PLA2 levels are reduced with the administration of glucocorticoids, the PLA2 response to endotoxin was investigated in volunteers pretreated with and without hydrocortisone.

METHODS

Carefully screened human subjects were studied under four conditions: (1) saline, (2) hydrocortisone, (3) endotoxin, and (4) hydrocortisone administration before endotoxin exposure. Pulse rate, blood pressure, temperature, and symptoms of endotoxemia were serially measured. Plasma for tumor necrosis factor concentrations and PLA2 activity was obtained.

RESULTS

After lipopolysaccharide, pulse rate and tumor necrosis factor concentrations rose at 1 to 2 hours; temperature increased maximally at 4 hours. PLA2 activity reached peak levels at 24 hours. With hydrocortisone pretreatment, a 50% reduction in the concentrations of tumor necrosis factor and PLA2 occurred. Significant correlations between other variables and PLA2 activity were not observed. The enzyme identified by monoclonal antibody was the secreted nonpancreatic PLA2 (SNP-PLA2).

CONCLUSIONS

The results of this study suggest that elevations in circulating SNP-PLA2 activity and systemic events associated with intravenous endotoxin administration are unrelated.

Plasmodium falciparum proteinases and red blood cell invasion

Malarial proteinases of the erythrocytic life-cycle are used to design new inhibitors capable of blocking the parasite's development. The Merozoite Proteinase for Erythrocytic Invasion (MPEI) of Plasmodium falciparum, a neutral proteinase, and the acidic Pf37 proteinase acting on spectrin as substrate, are good candidates for this kind of strategy.

Lymphotoxin beta, a novel member of the TNF family that forms a heteromeric complex with lymphotoxin on the cell surface

The lymphokine tumor necrosis factor (TNF) has a well-defined role as an inducer of inflammatory responses; however, the function of the structurally related molecule lymphotoxin (LT alpha) is unknown. LT alpha is present on the surface of activated T, B, and LAK cells as a complex with a 33 kd glycoprotein, and cloning of the cDNA encoding the associated protein, called lymphotoxin beta (LT beta), revealed it to be a type II membrane protein with significant homology to TNF, LT alpha, and the ligand for the CD40 receptor. The gene for LT beta was found next to the TNF-LT locus in the major histocompatibility complex (MHC), a region of the MHC with possible linkage to autoimmune disease. These observations raise the possibility that a surface LT alpha-LT beta complex may have a specific role in immune regulation distinct from the functions ascribed to TNF.

Elaboration of interleukin 1-receptor antagonist is not attenuated by glucocorticoids after endotoxemia

The body's response to infection/inflammation is initiated by the elaboration of cytokines, such as tumor necrosis factor, interleukin 1-beta (IL-1-beta), IL-6, and IL-8. Cytokines, in turn, stimulate the pituitary-adrenal axis, and it has been suggested that the corticosteroids elaborated serve as negative feedback signals to diminish inflammatory events. To test this hypothesis, we administered hydrocortisone shortly before endotoxin administration to normal volunteers. Steroids greatly reduced the clinical response to endotoxin and attenuated the appearance of tumor necrosis factor, IL-6, and IL-8 in the circulation. In contrast, IL-1-receptor antagonist, a competitive antagonist of the IL-1 receptor, was unaffected by steroid administration. These data suggest that IL-1-receptor antagonist may act in synergism with corticosteroids to reduce inflammation. Elevation of concentrations of these two factors, corticosteroids and IL-1-receptor antagonist, in plasma appears to be the mechanism used by the body to overcome the effects of inflammatory cytokines.

Peptide derivatives specific for a Plasmodium falciparum proteinase inhibit the human erythrocyte invasion by merozoites

A specific proteinase of P. falciparum merozoites has been detected by using hydrosoluble fluorogenic peptidic substrates synthesized by classical peptide chemistry; their N-terminal end was acylated by a gluconoyl group that protects them from aminopeptidase degradation and increases their hydrosolubility, and their carboxylic end was substituted by a 3-amino-9-ethylcarbazole group. The sequence Val-Leu-Gly-Lys was found to be the most specific substrate. On this basis, reversible peptidic inhibitors were synthesized by substituting the C-terminal lysyl residue, at the proteolytic site, by different alkylamines and amino alcohols. The activity of these compounds, studied on the P. falciparum proteinase and in in vitro cultures, strongly suggests a specific effect of this peptidic sequence on the reinvasion process. The peptidic inhibitors do not impair the release of merozoites from schizonts, but selectively inhibit the invasion step leading to the formation of rings. Although the natural target of this enzyme is not yet known, these specific peptide inhibitors could lead to a new antimalarial approach.

Human extracellular recombinant phospholipase A2 induces an inflammatory response in rabbit joints

Phospholipase A2 (PLA2) enzymes hydrolyze membrane phospholipids liberating fatty acid and lysophospholipid. This event is thought to be the rate-limiting step in the generation of the lipid proinflammatory mediators, the eicosanoids and possibly platelet-activating factor. For this reason, extracellular forms of PLA2 have been postulated to be a component of the inflammatory cascade in certain biologic settings. In the synovial fluid of patients with inflammatory arthritides, substantial amounts of PLA2 activity have been found, and subsequently, one enzyme was purified, cloned, and expressed. Here we show that the pure recombinant enzyme free of any proinflammatory contaminants elicits a dramatic inflammatory, arthritogenic response when injected into the joint space of healthy rabbits. Within 24 h, extensive leukocyte infiltration and hyperplasia of the synovial lining cells were observed, and prostaglandin production in the joint space increased. In comparison, pancreatic PLA2(2) had little activity in this system, whereas a very inflammatory cobra venom enzyme was intermediate in its effects. In view of the presence of the enzyme in inflamed joints, the fact that its synthesis and secretion can be induced by proinflammatory cytokines and its proinflammatory biologic activity, we suggest that synovial PLA2 plays an exacerbating role in acute episodes in chronic inflammatory conditions such as rheumatoid arthritis.

Human extracellular recombinant phospholipase A2 induces an inflammatory response in rabbit joints

Phospholipase A2 (PLA2) enzymes hydrolyze membrane phospholipids liberating fatty acid and lysophospholipid. This event is thought to be the rate-limiting step in the generation of the lipid proinflammatory mediators, the eicosanoids and possibly platelet-activating factor. For this reason, extracellular forms of PLA2 have been postulated to be a component of the inflammatory cascade in certain biologic settings. In the synovial fluid of patients with inflammatory arthritides, substantial amounts of PLA2 activity have been found, and subsequently, one enzyme was purified, cloned, and expressed. Here we show that the pure recombinant enzyme free of any proinflammatory contaminants elicits a dramatic inflammatory, arthritogenic response when injected into the joint space of healthy rabbits. Within 24 h, extensive leukocyte infiltration and hyperplasia of the synovial lining cells were observed, and prostaglandin production in the joint space increased. In comparison, pancreatic PLA2(2) had little activity in this system, whereas a very inflammatory cobra venom enzyme was intermediate in its effects. In view of the presence of the enzyme in inflamed joints, the fact that its synthesis and secretion can be induced by proinflammatory cytokines and its proinflammatory biologic activity, we suggest that synovial PLA2 plays an exacerbating role in acute episodes in chronic inflammatory conditions such as rheumatoid arthritis.