Increased serum endotoxin and elevated CD14 and IL-1beta expression in a rat model of cerebrogenic multiple organ dysfunction syndrome

OBJECTIVES

To study the mechanisms underlying cerebrogenic multiple organ dysfunction syndrome (CMODS) through investigation of endotoxin levels and the expression of endotoxin receptor CD14 and interleukin IL-1beta mRNAs in a rat CMODS model.

METHODS

Acute cerebral hemorrhage was induced in Wistar rats by focal intracerebral injection of collagenase into the caudate nucleus. Serum endotoxin levels were quantitated using a chromogenic limulus lysate method; CD14 endotoxin receptor mRNA and IL-1beta mRNA levels in lung and intestine were determined by in situ hybridization.

RESULTS

Serum endotoxin levels increased after 12 h, reaching a peak after 24 h, and declined to control levels at 72 h. The increase was statistically significant (P<0.05) compared to unoperated controls and the sham-operated group respectively. CD14 mRNA in lung and intestine increased after 12 h, peaked after 24-36 h, and then declined after 48 h. IL-1beta mRNA levels were also increased in lung and intestine (P<0.05), peaking at 36 h and declining thereafter. Expression levels of both CD14 and IL-1beta mRNAs correlated significantly with serum endotoxin levels (Plt;0.01). We conclude that acute cerebral hemorrhage results in endotoxemia and widespread increases in CD14 and IL-1beta expression. We suggest that acute cerebrovascular challenge leads to a stress/shock response that compromises the intestinal mucosal barrier. In turn, this allows endotoxin translocation into the body that provokes the release of pro-inflammatory lymphokines, leading to a systemic inflammatory response syndrome (SIRS) that culminates in multiple organ dysfunction.

Paediatric PNET: pre-surgical MRI features

AIM

To describe the preoperative magnetic resonance imaging (MRI) characteristics of primitive neuroectodermal tumours (PNETs), in particular the diffusion-weighted imaging (DWI), MR spectroscopy (MRS) features and cerebrospinal fluid (CSF) tumour dissemination.

MATERIAL AND METHODS

Twelve patients with PNETs were reviewed: nine with medulloblastoma and three with supratentorial PNETs (SPNETs). The MRI examination included contrast-enhanced intracranial and spinal MRI, and in some patients, gradient recalled echo, fluid-attenuated inversion recovery (FLAIR), DWI, and MRS.

RESULTS

All PNETs were either hypointense or isointense on T1-weighted images. Ten of the 12 tumours were either isointense or hypointense on T2-weighted images, and 11 were isointense on FLAIR images. Patients with SPNETs had large, vascular and haemorrhagic tumours. On DWI, all PNETs were hyperintense and had restricted apparent diffusion coefficient. MRS (two patients with medulloblastoma and one with a SPNET), showed elevated choline, decreased N-acetyl aspartate, and a small taurine peak in all three patients. Intraspinal tumour dissemination, visible as uniform or nodular enhancement coating the conus medullaris, was detected in six of 12 patients, two of whom also had intracranial dissemination.

CONCLUSION

PNETs have a characteristic imaging appearance on FLAIR, DWI and MRS, which may help in differentiating these highly cellular neoplasms from other tumours. There is CSF tumour dissemination in a high proportion of patients, and spinal imaging is important for disease staging and to formulate treatment protocols.

High affinity promotes more effective ADCC by anti-HER2/neu monoclonal antibodies

2538

Background: Although monoclonal antibodies have emerged as useful cancer therapeutics, the antibody structural features and biologic properties that maximize therapeutic benefit are not fully understood. Antibody-dependent cellular cytotoxicity (ADCC) is believed to be a major mechanism of some anti-cancer antibodies. Herein, we describe the relationship between antibody affinity and the biologic properties of ADCC. Methods: A series of human IgG1 antibodies was created from the anti-HER2/neu C6.5 scFv and its affinity mutants (affinity ranging from 10−7 to 10−11 M). The IgGs were tested for their ability to elicit ADCC using a standard 51Cr-release assay. The ability of these IgGs to inhibit tumor cell proliferation and to induce apoptosis was evaluated using a colorimetric cell proliferation assay and homogeneous caspase assay/Annexin-V-FLUOS assay, respectively. Three tumor cell lines with differing levels of HER2/neu expression were used as target cells, and unactivated human PBMC from healthy donors were the effector cells. Results: There was a clear influence of both intrinsic and functional affinity on ADCC, with higher levels of peak cytotoxicity as apparent affinity approached 10−11 M. Among the antibodies with apparent affinity of 10−11 M, antibodies with higher intrinsic affinities elicited more ADCC. There also was an affinity-dependent increase in cytotoxicity at lower antibody concentrations and lower effector: target ratios. These antibodies elicited more cytotoxicity against tumor cells expressing high levels of HER2/neu than against cells expressing lower amounts of HER2/neu. None of these IgGs inhibited tumor cell proliferation, or induced apoptosis. Conclusions: Additional studies are needed to determine why, at the same functional avidity, ADCC is improved in antibodies with higher intrinsic affinities. These findings justify the examination of high affinity antibodies for ADCC promotion, although the impaired tumor targeting associated with high affinity may be an important confounding factor in the design of unconjugated anti-tumor antibodies. A careful examination of antibody structure: function relationships is required to develop optimized therapeutic unconjugated antibodies.

No significant financial relationships to disclose.

Sequence variation within botulinum neurotoxin serotypes impacts antibody binding and neutralization

The botulinum neurotoxins (BoNTs) are category A biothreat agents which have been the focus of intensive efforts to develop vaccines and antibody-based prophylaxis and treatment. Such approaches must take into account the extensive BoNT sequence variability; the seven BoNT serotypes differ by up to 70% at the amino acid level. Here, we have analyzed 49 complete published sequences of BoNTs and show that all toxins also exhibit variability within serotypes ranging between 2.6 and 31.6%. To determine the impact of such sequence differences on immune recognition, we studied the binding and neutralization capacity of six BoNT serotype A (BoNT/A) monoclonal antibodies (MAbs) to BoNT/A1 and BoNT/A2, which differ by 10% at the amino acid level. While all six MAbs bound BoNT/A1 with high affinity, three of the six MAbs showed a marked reduction in binding affinity of 500- to more than 1,000-fold to BoNT/A2 toxin. Binding results predicted in vivo toxin neutralization; MAbs or MAb combinations that potently neutralized A1 toxin but did not bind A2 toxin had minimal neutralizing capacity for A2 toxin. This was most striking for a combination of three binding domain MAbs which together neutralized >40,000 mouse 50% lethal doses (LD(50)s) of A1 toxin but less than 500 LD(50)s of A2 toxin. Combining three MAbs which bound both A1 and A2 toxins potently neutralized both toxins. We conclude that sequence variability exists within all toxin serotypes, and this impacts monoclonal antibody binding and neutralization. Such subtype sequence variability must be accounted for when generating and evaluating diagnostic and therapeutic antibodies.

Molecular Evolution of Antibody Affinity for Sensitive Detection of Botulinum Neurotoxin Type A

Botulism is caused by botulinum neurotoxin (BoNT), the most poisonous substance known. Potential use of BoNT as a biothreat agent has made development of sensitive assays for toxin detection and potent antitoxin for treatment of intoxication a high priority. To improve detection and treatment of botulism, molecular evolution and yeast display were used to increase the affinity of two neutralizing single chain Fv (scFv) antibodies binding BoNT serotype A (BoNT/A). Selection of yeast displayed scFv libraries was performed using methods to select for both increased association rate constant (k(on)) and decreased dissociation rate constants (k(off)). A single cycle of error prone mutagenesis increased the affinity of the 3D12 scFv 45-fold from a K(D) of 9.43x10(-10)M to a K(D) of 2.1x10(-11)M. Affinity of the HuC25 scFv was increased 37-fold from 8.44x10(-10)M to 2.26x10(-11)M using libraries constructed by both random and site directed mutagenesis. scFv variable region genes were used to construct IgG for use in detection assays and in vivo neutralization studies. While IgG had the same relative increases in affinity as scFv, (35-fold and 81-fold, respectively, for 3D12 and HuC25) higher solution equilibrium binding constants were observed for the IgG, with the 3D12 K(D) increasing from 6.07x10(-11)M to 1.71x10(-12)M and the HuC25 K(D) increasing from 4.51x10(-11)M to 5.54x10(-13)M. Affinity increased due to both an increase in k(on), as well as slowing of k(off). Higher affinity antibodies had increased sensitivity, allowing detection of BoNT/A at concentrations as low as 1x10(-13)M. The antibodies will also allow testing of the role of affinity in in vivo toxin neutralization and could lead to the generation of more potent antitoxin.

Dengue virus infection of human microvascular endothelial cells from different vascular beds promotes both common and specific functional changes

Dengue shock syndrome (DSS), the major life threatening outcome of severe dengue disease, which occurs in some patients in the course of dengue infection, is the consequence of plasma leakage in the microvascular territories. Data from clinical and in vitro studies suggest that an inadequate immunological response is partly responsible for the pathophysiology of DSS, but few is known concerning the consequences of direct infection of endothelial cells by dengue virus per se. In this study, an attempt was made to study the response of two microvascular human cell lines originating, respectively, from liver and dermis to infection by a dengue type 2 virus, by analyzing the virus-induced modulation of functional markers. It is shown that the two microvascular cell lines exhibit both common and specific behaviors upon infection. In particular, LSEC and HMEC-1 replicate efficiently the low-passage virus and respond to infection by over-producing inflammatory mediators involved in the cross talk with circulating immune cells. However, direct infection modulates differently the cell surface expression of molecules critically involved in the interactions between endothelial and inflammatory cells. ICAM-1 and HLA-I are up regulated as a consequence of infection in LSEC whereas direct infection results in downregulation of ICAM-1 in HMEC-1. The present results show that infection of human microvascular cells by unadapted dengue virus results in both common and specific activation patterns depending likely on the tissue origin of the cells, thus suggesting that endothelia from different territories may contribute differently to the pathophysiological events in the course of dengue infection.

Primary immunodeficiency diseases in Singapore--the last 11 years

OBJECTIVES

To describe the clinical features, disease complications, treatment modalities and overall outcome of 39 local patients with Primary Immunodeficiency Diseases (PID) in Singapore over the last 11 years.

METHODS

Paediatric and adult patients who presented to the The Children's Medical Institute, National University Hospital, Tan Tock Seng Hospital and KK Women's and Children's Hospital between January 1990 and December 2000 were identified. Their diagnoses were categorised into six groups according to the IUIS (International Union of Immunological Societies, affiliated to World Health Organisation) classification: antibody deficiencies, combined immunodeficiencies, immunodeficiencies associated with other major defects, congenital phagocytic defects, complement deficiencies and other well-defined immunodeficiency syndromes. Patients were selected from screening of inpatients with discharge diagnoses associated with primary immunodeficiency and of patients undergoing tests for immunodeficiency. Patient data were collated from case files and compiled using a standard questionnaire.

RESULTS

There were 39 Singaporean patients diagnosed and treated for PID during the study period. The age at diagnosis ranged from three weeks to 69 years. Antibody deficiency (41%) was the most common form of PID. Seven patients had a family history of PID. Recurrent bacterial respiratory tract infections were the most common clinical manifestation. Associated conditions included autoimmune diseases, allergies and malignancies. Infection was the commonest cause of mortality. Eighteen patients (46.2%) with antibody or combined deficiencies received regular intravenous immunoglobulin (IVIG) as the primary treatment modality. Two children successfully received sibling-matched haematopoietic stem cell transplantation (HSCT).

CONCLUSIONS

Antibody deficiencies are the most common form of PID in Singapore. Treatment with antibiotics, IVIG and HSCT are the main therapeutic modalities currently available. Early referral to an immunologist is needed to achieve good outcomes.

Ex vivo gene therapy in autologous bone marrow stromal stem cells for tissue-engineered maxillofacial bone regeneration

This study examines the clinical relevance of tissue engineering integrating gene therapy and polymer science to bone regeneration. Bilateral maxillary defects (3 x 1.2 cm(2)) in 20 miniature swine were bridged with a bioresorbable internal splint. Constructs were created using ex vivo adenovirus bone morphogenetic protein (BMP)-2-mediated gene transfer to the expanded bone marrow mesenchymal stem cells (MSCs) 7 days before implantation. Controls were performed using adenovirus beta-galactosidase. The BMP-2 cell/construct displayed white solid bone formation after 3 months. Meanwhile, the hematoxylin and eosin and Von Kossa stains demonstrated exhibited mature woven bone with good mineralization. Additionally, three-dimensional computer tomography imaging revealed a nearly complete infraorbital rim repair. Quantitative analysis demonstrated a significant difference (P<0.001) in bone formation. Finally, biomechanical testing revealed no statistically significant difference in the maximal compressive strength of new bone formed by BMP-2 cell constructs and the normal maxilla. The data evidenced de novo bone formation capable of sustaining axial compressive loads. The measurement results showed that ex vivo replication defective adenovirus-mediated human BMP-2 gene transfer to MSCs enhances autologous bone formation in the repair of maxillary defects.

Paediatric extracranial germ cell tumours: a retrospective review

INTRODUCTION

Germ cell tumours (GCTs) are rare, constituting 3% of all childhood malignancies. The aim of this study was to analyse the epidemiology and outcome of these patients.

MATERIALS AND METHODS

A retrospective, cohort study was conducted on 38 paediatric patients presenting with extracranial GCTs, treated at the Singapore General Hospital, Tan Tock Seng Hospital and Kandang Kerbau Women's and Children's Hospital from 1 January 1989 to 30 June 1999. The median age at diagnosis was 1.7 years (0 to 13 years).

RESULTS

There was no sex or racial preponderance. Eighteen patients (47.3%) had teratomas, 16 (42.1%) had yolk sac tumours, 1 (2.6%) had dysgerminoma and 3 (7.9%) had mixed GCTs. Thirty-four patients (89.5%) had Stage I disease, 1 (2.6%) had Stage II disease, 1 (2.6%) had Stage III disease and 2 (5.3%) had metastatic disease. Complete tumour resection was achieved in 36 of the 38 patients (95%). Cisplatin-based combination chemotherapy was given to 11 patients (28.9%). None of the patients received radiotherapy. Complications from chemotherapy included anaemia requiring packed red cell transfusion (n = 3), Port-a-cath sepsis requiring removal (n = 1), febrile neutropenia (n = 1) and nephropathy (n = 1).

CONCLUSION

Using the Kaplan-Meier life tables, the overall and event-free survivals at 10 years for the patients with malignant GCTs were 96% and 88%, respectively, with a mean follow-up period of 5.1 years (0.7 to 10 years). The majority of the patients presented with early Stage I disease and this contributed to our high survival rate.

Primary histiocytic lymphoma of the central nervous system: a neoplasm frequently overshadowed by a prominent inflammatory component

True histiocytic lymphoma, as defined by strict criteria, is a very rare neoplasm. We describe three cases occurring as primary tumors in the central nervous system. The patients, two females and one male, ranged in age from 11 to 69 years. The tumors involved the brain in two cases and spinal cord in one, with a size ranging from 7 to 17 mm. Two patients died at 4 months and 8 months, respectively, and one was alive with disease at 5 months. Pathologically, the tumors comprised groups and sheets of noncohesive large cells with pleomorphic vesicular nuclei, distinct nucleoli, and abundant eosinophilic cytoplasm. A dense inflammatory infiltrate consisting of neutrophils, lymphocytes, plasma cells, and histiocytes was present, with multiple foci of necrosis and abscess formation. All three cases demonstrated an identical immunophenotype: positive for CD68 and lysozyme; focally positive for S-100 protein, CD45RB, and CD4; and negative for CD3, CD20, CD21/CD35, CD1a, CD30, ALK1, myeloperoxidase, glial fibrillary acidic protein, and cytokeratin. The proliferative index ranged from 20% to 35%. Ultrastructural examination further confirmed the histiocytic nature of the tumor cells, characterized by irregularly folded or multisegmented nuclei and abundant cytoplasm containing lysosomes; Birbeck granules, interdigitating cell processes, and cell junctions were not found. Although the presence of abundant inflammatory cells could obscure the neoplastic histiocytes, making the distinction from inflammatory conditions difficult, awareness of this unusual histologic feature and the invariable finding of pleomorphic cells in some areas of the lesion permit the correct diagnosis to be made.

Beta cell replacement for the treatment of diabetes

The replacement of insulin-producing beta cells by islet transplantation can efficiently reverse diabetes. The recent improvements in clinical results were made possible by transplanting higher islet masses and through the introduction of new immunosuppressive protocols that avoid diabetogenicity. The need for alternatives to continuous immunosuppression, and an unlimited source of glucose-sensitive, insulin-secreting tissue, is emerging. In this review we discuss the various key steps in islet transplantation and offer perspectives for future developments in the replacement of insulin-producing beta cells for the treatment of type I diabetes.

BMP-12 gene transfer augmentation of lacerated tendon repair

Bone morphogenetic protein (BMP) 12 is a recently discovered member of the human BMP family. It is the human homolog of mouse growth/differentiation factor (GDF)-7. Previously we reported that injection of mesenchymal progenitor cells transferred with the BMP-12 gene into the muscles of nude mice induced tendon-like tissue formation. In this study, we further investigated the effect of BMP-12 gene transfer on tendon cells. We observed that adenovirus mediated in vitro BMP-12 gene transfer into chicken tendon cells increased type I collagen synthesis. No change in alkaline phosphatase activity was observed following BMP-12 gene transfer. We also determined that BMP-12 gene transfer into a complete tendon laceration chicken model resulted in a two-fold increase of tensile strength and stiffness of repaired tendons, indicating improved tendon healing in vivo. We conclude that BMP-12 gene transfer is a promising procedure for improving the tendon repair process.

Pathogenesis of cerebral malaria: recent experimental data and possible applications for humans

Malaria still is a major public health problem, partly because the pathogenesis of its major complication, cerebral malaria, remains incompletely understood. Experimental models represent useful tools to better understand the mechanisms of this syndrome. Here, data generated by several models are reviewed both in vivo and in vitro; we propose that some pathogenic mechanisms, drawn from data obtained from experiments in a mouse model, may be instrumental in humans. In particular, tumor necrosis factor (TNF) receptor 2 is involved in this syndrome, implying that the transmembrane form of TNF may be more important than the soluble form of the cytokine. It has also been shown that in addition to differences in immune responsiveness between genetically resistant and susceptible mice, there are marked differences at the level of the target cell of the lesion, namely, the brain endothelial cell. In murine cerebral malaria, a paradoxical role of platelets has been proposed. Indeed, platelets appear to be pathogenic rather than protective in inflammatory conditions because they can potentiate the deleterious effects of TNF. More recently, it has been shown that interactions among platelets, leukocytes, and endothelial cells have phenotypic and functional consequences for the endothelial cells. A better understanding of these complex interactions leading to vascular injury will help improve the outcome of cerebral malaria.

Quantitative variation in vascular endothelial growth factor mRNA expression during early flexor tendon healing: an investigation in a canine model

Vascular endothelial growth factor (VEGF) is a potent mediator of angiogenesis, with direct mitogenic activity on cells of endothelial origin. We quantified the temporal accumulation of VEGF mRNA at the repair site of an in vivo canine intrasynovial flexor tendon repair and rehabilitation model by means of quantitative Northern blot analysis, in order to detail a molecular signal involved in the intrinsic angiogenic process that accompanies early flexor tendon healing. Significant accumulation of VEGF mRNA occurred at the flexor tendon repair site at 7 days post-operatively, with peak levels seen at post-operative days 7 and 10. Levels returned to baseline by day 14. Local VEGF mRNA accumulation at the repair site temporally precedes and is spatially distinct from the vascular ingrowth itself, which has been shown to occur maximally at day 17. These data suggest that cells within the flexor tendon repair site are involved in molecular processes other than the synthesis of extracellular matrix, such as modulation of angiogenesis.

Antibodies in haystacks: how selection strategy influences the outcome of selection from molecular diversity libraries

Antibodies against most antigens can be isolated from high quality phage antibody libraries. However, not all antibodies binding a particular antigen are necessarily found when standard selections are performed. Here we investigate the effect of two different selection strategies on the isolation of antibodies against a number of different antigens, and find that these different strategies tend to select different antibodies, with little overlap between them. This indicates that the full diversity of these libraries is not tapped by a single selection strategy and that each selection strategy imposes different selective criteria in addition to that of antigen binding. To fully exploit such libraries, therefore, many different selection strategies should probably be employed for each antigen. The use of alternative strategies should be considered when selection apparently fails, or when the number of different antibodies recognizing an antigen needs to be maximised. Furthermore, the microtitre selection strategy developed is likely to prove useful in the application of phage antibody libraries to the human genome project, allowing the high throughput selection of antibodies against multiple antigens simultaneously.

In vivo recombination as a tool to generate molecular diversity in phage antibody libraries

The creation of diversity in populations of polypeptides has become an important tool in the derivation of polypeptides with useful characteristics. This requires efficient methods to create diversity coupled with methods to select polypeptides with desired properties. In this review we describe the use of in vivo recombination as a powerful way to generate diversity. The novel principles for the recombination process and several applications of this process for the creation of phage antibody libraries are described. The advantage and disadvantages are discussed and possible future exploitation presented.

Evidence for expression of estrogen receptor cofactor messenger ribonucleic acid in the ovary and uterus of domesticated animals (sheep, cow and pig)

Expression levels of estrogen receptor cofactors (coactivators or corepressors) in specific tissue compartments and cells are thought to influence the expression of estrogen responsive genes and thereby influence overall hormonal responsiveness of target tissues. To date, the presence of cofactors has been reported in tissues from humans, rats and mice. We analyzed the presence and distribution of messenger ribonucleic acids (mRNAs) encoding several transcriptional cofactors in the ovary and uterus of three domestic animal species, the sheep, cow and pig. Northern analysis for cofactors SRC-1, GRIP1, RAC3, p300, RIP140, and SPA showed expression in ovaries from all three species. In addition, lower expression of SRC-1, GRIP1, RAC3, p300, and RIP140 mRNAs was observed during the luteal phase (day 10-12 of the estrous cycle) than at estrus (day 0); however, SPA transcript levels remained unchanged. We then examined expression of mRNAs for changing (SRC-1, RIP140) and constitutively expressed (SPA) cofactors in ovine ovaries. SRC-1 and RIP140 transcripts in corpus luteum were lower compared to the surrounding ovarian tissue. SPA mRNA expression, however, was similar in corpus luteum and surrounding tissues. To determine which ovarian cell types express SRC-1, RIP140, and SPA, in situ hybridization was performed on sheep ovaries. Silver grains corresponding to these cofactors were seen in ovarian granulosa, theca and stromal cells, but appeared to be most abundant in the granulosa cells. Expression of SRC-1 and RIP140 in corpus luteum, however, was reduced compared to expression in follicular cells. Finally, we examined cofactor expression in ovine, bovine, and porcine uterus. Northern blot analysis for SRC-1, GRIP1, RAC3, p300, and RIP140 mRNAs showed higher expression in extracts of the endometrium compared to whole uterus. We provide the first evidence for the presence of estrogen receptor cofactor mRNAs in the ovary and uterus of three domestic animal species. We suggest that coactivators are conserved among species and associated with hormonal responsiveness of reproductive tract tissues in sheep, cow and pig.

In vitro and in vivo induction of bone formation using a recombinant adenoviral vector carrying the human BMP-2 gene

It has been well established that bone morphogenetic protein-2 (BMP-2) can induce bone formation both in vivo and in vitro, although high concentrations (up to milligrams) of BMP-2 have been required to achieve this effect in vivo. Further, clinical applications are usually limited to a single dose at the time of implantation. In an attempt to prolong the transforming effect of BMP-2 we used a recombinant adenoviral vector carrying the human BMP-2 gene (Adv-BMP2) to transduce marrow-derived mesenchymal stem cells (MSC) of skeletally mature male New Zealand white rabbits. The pluripotential MSC were incubated with Adv-BMP2 overnight followed by culture in growth medium for 1 week. Assays on tissue cultures demonstrated that these Adv-BMP2 transduced MSC produced BMP-2 protein, differentiated into an osteoprogenitor line, and induced bone formation in vitro. These MSC had increased alkaline phosphatase activity, increased expression of type I collagen, osteopontin, and osteocalcin mRNA, and induced matrix mineralization compared with both non-transduced cells and cells transduced with a control adenoviral construct. To analyze the osteogenic potential in vivo, Adv-BMP2-transduced MSC were autologously implanted into the intertransverse process space between L5 and L6 of the donor rabbits. The production of new bone was demonstrated by radiographic examination 4 weeks later in areas implanted with cells transduced with Adv-BMP2, whereas no bone was evident at sites implanted with cells transduced with the control adenoviral construct. Histological examination further confirmed the presence of new bone formation. These accumulated data indicate that it is possible to successfully transduce mesenchymal stem cells with a recombinant adenoviral vector carrying the gene for BMP-2 such that these cells will produce BMP-2, differentiate into an osteoprogenitor line, and induce bone formation both in vitro and in vivo. Moreover, incubation of the Adv-BMP2-transduced cells for an additional 7 days in culture before transplantation enhances the success rate in bone formation (three out of three) as compared with our previous report (one out of five, Calcif Tissue Int 63:357-360, 1998).

In Vitro andIn Vivo induction of bone formation using a recombinant adenoviral vector carrying the human BMP-2 gene

It has been well established that bone morphogenetic protein-2 (BMP-2) can induce bone formation bothin vivo andin vitro, although high concentrations (up to milligrams) of BMP-2 have been required to achieve this effectin vivo. Further, clinical applications are usually limited to a single dose at the time of implantation. In an attempt to prolong the transforming effect of BMP-2 we used a recombinant adenoviral vector carrying the human BMP-2 gene (Adv-BMP2) to transduce marrow-derived mesenchymal stem cells (MSC) of skeletally mature male New Zealand white rabbits. The pluripotential MSC were incubated with Adv-BMP2 overnight followed by culture in growth medium for 1 week. Assays on tissue cultures demonstrated that these Adv-BMP2 transduced MSC produced BMP-2 protein, differentiated into an osteoprogenitor line, and induced bone formationin vitro. These MSC had increased alkaline phosphatase activity, increased expression of type I collagen, osteopontin, and osteocalcin mRNA, and induced matrix mineralization compared with both nontransduced cells and cells transduced with a control adenoviral construct. To analyze the osteogenic potentialin vivo, Adv-BMP2-transduced MSC were autologously implanted into the intertransverse process space between L5 and L6 of the donor rabbits. The production of new bone was demonstrated by radiographic examination 4 weeks later in areas implanted with cells transduced with Adv-BMP2, whereas no bone was evident at sites implanted with cells transduced with the control adenoviral construct. Histological examination further confirmed the presence of new bone formation. These accumulated data indicate that it is possible to successfully transduce mesenchymal stem cells with a recombinant adenoviral vector carrying the gene for BMP-2 such that these cells will produce BMP-2, differentiate into an osteoprogenitor line, and induce bone formation bothin vitro andin vivo. Moreover, incubation of the Adv-BMP2-transduced cells for an additional 7 days in culture before transplantation enhances the success rate in bone formation (three out of three) as compared with our previous report (one out of five, Calcif Tissue Int 63:357-360, 1998).

Determination of the platelet activating factor in silicotic patients and its effect on fibroblasts

Platelet-activation factor (PAF), one of the potent proinflammatory mediators, is produced from a large range of cells, including polymorphonuclear neutrophils, monocytes, and natural killer cells. To study the role of PAF in the pathogenesis of silicosis, we determined the PAF in silicotic patients and in healthy persons. The results showed that the concentration of PAF in the plasma of silicotic patients was significantly higher than that of healthy persons. Ourin vitro experimental results showed that the total numbers of fibroblasts were markedly raised with added PAF from 0 to 1 μ g/ml. Adding 1 μ g/ml PAF significantly increased the total numbers of fibroblasts after culture for 48, 72, 96 hrs. Therefore, we suggest that PAF be possibly involved in the pathogenesis of silicosis. However, the mechanism remains to be further elucidated.

Xenogeneic islet re-transplantation in mice triggers an accelerated, species-specific rejection

Xenogeneic islets could provide an unlimited source of tissue for the treatment of diabetes, and could in theory be transplanted repeatedly in a recipient. However, little is known on the consequences of islet re-transplantation in a recipient who has rejected a first graft. In this study, we investigated the functional consequence of xeno islet re-transplantation in mice sensitized with islets from different species. Sprague-Dawley (SD)-rat islets transplanted in sensitized C57/Bl6 mice that rejected either SD- or Lewis-rat islets underwent accelerated rejection. However, accelerated rejection was not found in mice sensitized with pig or human islets, suggesting that accelerated rejection was species specific. Immunohistochemistry showed increased binding of antibodies and accelerated leucocyte infiltration on re-grafted islets in sensitized mice. In situ apoptosis detection indicated that islet cell apoptosis was correlated with the time of leucocyte infiltration, but not with the time of antibody binding. In vitro experiments with cultured islet cells showed that although antibody binding was increased after incubation with sensitized mouse serum, islet cell cytotoxicity was not increased, suggesting that humoral immunity did not play a direct role in islet destruction. These results indicate that there is a cell-mediated, species-specific accelerated rejection after re-transplantation of xenogeneic islets.

In vivo gene transfer into tendon by recombinant adenovirus

Recombinant adenovirus mediated Escherichia coli lacZ gene transfer into chicken tendon and tendon sheath has been reported in the current study. The constructed recombinant virus carrying lacZ gene was injected between tendon and tendon sheath to conduct in vivo gene transfer. During the course of the study, each tendon received a 10 uL injection containing 10(5) plaque forming units of recombinant adenovirus with beta-galactosidase gene. The samples were harvested at 3 days, 30 days, and 75 days after injection. For the virus dose-transduction rate study, five different doses were injected to groups of chicken tendons. LacZ gene transfer was detected for its coding product beta-galactosidase by staining with X-gal solution. Results showed that the tendon and tendon sheath received the gene transfer with blue staining. The transferred lacZ gene remained stable for 75 days in the tendon and tendon sheath. A virus dose-dependent pattern of transduction rate was observed in the gene transferred tendons. The area of tendon transduction was approximately 2% for 3 x 10(6) plaque forming units recombinant adenovirus with beta-galactosidase versus 40% for 6 x 10(7) plaque forming units recombinant adenovirus with beta-galactosidase gene. The data suggested that functional exogene could be transferred into the tendon and tendon sheath by the same strategy to improve healing and avoid adhesion.

Reversible immortalization of human primary cells by lentivector-mediated transfer of specific genes

We exploited the ability of lentiviral vectors to govern the stable transduction of cells irrespective of their cycling status to induce the reversible immortalization of human primary cells. First, bicistronic HIV-derived lentiviral vectors expressing GFP- and the HSV1 thymidine kinase and containing the LoxP sequence in their LTR (HLox) were used to transduce HeLa cells. Cre expression led to efficient proviral deletion, and unexcised cells could be eliminated by ganciclovir treatment. A human liver biopsy was then exposed to a combination of HLox vectors that harbored either the SV40 large T (TAg) or the human telomerase (hTERT) DNAs in place of GFP. This led to the isolation of liver sinusoidal endothelial cell (LSEC) clones that exhibited an immortalized phenotype while retaining most of the features of primary hLSEC. Complete growth arrest of these cells was observed in 2 days of Cre expression, and the resulting stationary culture could be kept for at least 2 weeks. Transduction of human adult pancreatic islets with HLox vectors coding for Tag and Bmi-1 also induced the proliferation of insulin-positive cells. These results indicate that lentivectors can be used to mediate the reversible immortalization of primary nondividing cells and should allow for the production of large supplies of a wide variety of human cells for both therapeutic and research purposes.

Thermodynamics of the bilinear-biquadratic spin-One heisenberg chain

The magnetic susceptibility and specific heat of the one-dimensional S = 1 bilinear-biquadratic Heisenberg model are calculated using the transfer matrix renormalization group. By comparing the results with the experimental data of LiVGe2O6 measured by Millet et al. [Phys. Rev. Lett. 83, 4176 (1999)], we find that the susceptibility data of this material, after subtracting the impurity contribution, can be quantitatively explained with this model. The biquadratic exchange interaction in this material is found to be ferromagnetic, i.e., with a positive coupling constant.

The binding of cocaine to cyclodextrins

Cocaine binds into beta-cyclodextrin, but not detectably into alpha- or gamma-cyclodextrin, in water solution. NMR studies indicate the geometry of the complex, which is confirmed by molecular mechanics calculations and binding studies on cocaine analogues and cyclodextrin dimers.

[An evaluation of adenosine triphosphate bioluminescence assay for tumor in vitro chemosensitivity testing]

This study was aimed at the feasibility of using ATP-bioluminescence assay for tumor in vitro chemosensitivity testing. With the use of this assay, the authors determined dose-response curve in mouse fibroma cell line L929 treated with chemotherapeutic agents, and investigated the different in vitro responses of 6 ovarian carcinomas (5 from fresh tumor tissues, 1 from ascites) treated with etopside, cis-plating, 5-fluorouracil and adriamycin. The results showed that the coefficients of variation for triplicate assays ranged from 1.2% to 15.8% which means high reproducibility of the assay. The single cell suspension (including < 30 cells clusters) could be separated from tissue fragments by means of enzyme cocktail (collagenase, Dnase, pronase). The viable cells were over 90%. This study demonstrates that ATP-bioluminescence assay is a sensitive, reliable and efficient method for tumor chemosensitivity testing. In this connection, the correlation between in vitro drug sensitivity and in vivo patient response is worth further studying.

[An adenosine triphosphate bioluminescence assay for detecting the number of living cells]

The method for detecting the number of living cells was studied. Using an adenosine triphosphate (ATP) bioluminescence assay, the present authors reported a perfect linear relationship between lg ATP concentrations and lg luminescence counts (r = 0.9963) as well as a relationship between lg number of cells and lg ATP luminescence counts (r = 0.9922). The detectable cells ranged from 10(2) to 10(6) cells/ml, the coefficients of variation 1-3%. This method is simple, accurate and sensitive and has a high reproducibility.

Exogenous cdk4 overcomes reduced cdk4 RNA and inhibition of G1 progression in hematopoietic cells expressing a dominant-negative CBF - a model for overcoming inhibition of proliferation by CBF oncoproteins

Core Binding Factor (CBF) is required for the development of definitive hematopoiesis, and the CBF oncoproteins AML1-ETO, TEL-AML1, and CBFbeta-SMMHC are commonly expressed in subsets of acute leukemia. CBFbeta-SMMHC slows the G1 to S cell cycle transition in hematopoietic cells, but the mechanism of this effect is uncertain. We have sought to determine whether inhibition of CBF-mediated trans-activation is sufficient to slow proliferation. We demonstrate that activation of KRAB-AML1-ER, a protein containing the AML1 DNA-binding domain, the KRAB repression domain, and the Estrogen receptor ligand binding domain, also slows G1, if its DNA-binding domain is intact. Also, exogenous AML1 overcame CBFbeta-SMMHC-induced inhibition of proliferation. Representational difference analysis (RDA) identified cdk4 RNA expression as an early target of KRAB-AML1 activation. Inhibition of CBF activities by KRAB-AML1-ER or CBFbeta-SMMHC rapidly reduced endogenous cdk4 mRNA levels, even in cells proliferating at or near control rates as a result of exogenous cdk4 expression. Over-expression of cdk4, especially a variant which cannot bind p16INK4a, overcame cell cycle inhibition resulting from activation of KRAB-AML1-ER, although cdk4 did not accelerate proliferation when expressed alone. These findings indicate that mutations which alter the expression of G1 regulatory proteins can overcome inhibition of proliferation by CBF oncoproteins. Oncogene (2000).

Endothelin-induced cardiac myocyte hypertrophy: role for focal adhesion kinase

Endothelin-1 (ET) produces neonatal rat ventricular myocyte (NRVM) hypertrophy and activates focal adhesion kinase (FAK) in other cell types. In the present study, we examined whether ET activated FAK in NRVM and whether FAK was necessary and/or sufficient for ET-induced NRVM hypertrophy. Chronic ET-1 stimulation (100 nM, 48 h) increased protein-to-DNA and myosin heavy chain (MHC)-to-DNA ratios and stimulated the assembly of newly synthesized MHC into sarcomeres. ET-1 also induced the assembly of focal adhesions and costameres, as evidenced by increased phosphotyrosine, FAK, and paxillin immunostaining. Acutely, ET treatment rapidly increased tyrosine phosphorylation of FAK and paxillin. FAK was also activated by phorbol 12-myristate 13-acetate (2 microM, 5 min). Pretreatment with chelerythrine (5 microM) or rottlerin (10 microM) completely blocked ET-induced FAK phosphorylation, indicating that protein kinase C activation was upstream of ET-induced FAK activation. In contrast, ET-induced FAK activation was not affected by blocking calcium influx via L-type voltage-gated calcium channels. Adenoviruses (Adv) containing FAK and FAK-related nonkinase (FRNK) were used to specifically define the role of FAK in ET-induced hypertrophy. ET stimulation failed to increase total protein-to-DNA or MHC-to-DNA ratios or to stimulate sarcomeric assembly in myocytes infected with Adv-FRNK. However, Adv-FAK alone did not increase total protein-to-DNA or MHC-to-DNA ratios and failed to increase the number or size of myofibrils as evidenced by double immunofluorescence labeling for MHC and FAK. Thus, although FAK is necessary for ET-induced NRVM hypertrophy, other ET-generated signals are also required to elicit the hypertrophic phenotype.

Human islet transplantation: lessons from 13 autologous and 13 allogeneic transplantations

BACKGROUND

A series of 13 islet autotransplantations and 13 islet allotransplantations performed between 1992 and 1999 at the University Hospital of Geneva are presented. Factors affecting the outcome are analyzed.

METHODS

Islet autotransplantation has been performed in seven patients with chronic pancreatitis and in six patients with benign tumors undergoing extensive pancreatectomy. Islet allografts were performed in C-peptide-negative patients simultaneously or after a kidney or lung transplantation. Each recipient received islets from one to four donors. Panel-reactive antibodies were monitored by microlymphocytotoxicity test.

RESULTS

Eleven of 13 patients who underwent autotransplantation maintained insulin independence for 6 months to 5 years. Two years after autologous islet transplantation, five of nine patients were insulin independent with an glycosylated hemoglobin of 5.9%. Three late islet failures occurred in patients with chronic pancreatitis. Islet yield was significantly lower in patients with chronic pancreatitis than in patients with benign tumors (2044 equivalent islet number/gram resected pancreas versus 5184 equivalent islet number/gram; P=0.037). In islet allotransplantation, no early graft loss was found. All 13 patients who underwent allotransplantation had basal C-peptide levels above 0.3 nmol/L for 3 months to 5 years. Mean glycosylated hemoglobin decreased from 9.1% before transplantation to 5.5% at month 3. Insulin independence was achieved in two type I diabetic patients. In four of six patients with graft failure, the graft had induced panel-reactive antibodies.

CONCLUSIONS

In islet autotransplantation, the reduced number of islets that can be isolated from fibrotic pancreata may be the major limiting factor. In islet allotransplantation, early graft function can now be consistently achieved. Islet allografts seem to be highly immunogenic, and chronic islet failure cannot be prevented consistently by conventional immunosuppression.

Involvement of ERK in BMP-2 induced osteoblastic differentiation of mesenchymal progenitor cell line C3H10T1/2

The signaling mechanisms responsible for bone morphogenetic protein (BMP) induced osteoblast differentiation remains poorly understood. Previous research demonstrated that Smad proteins are the substrates and the mediators of BMP bound serine/threonine receptor kinase. In the present study, we examined the possible involvement of extracellular signal-regulated kinase (Erk) in the BMP induced osteoblast differentiation of mesenchymal progenitor cell C3H10T1/2. Our results indicate that BMP-2 inducement increased MAP kinase activity in mesenchymal progenitor cell line C3H10T1/2. Contrary to previous reports, this increased MAP kinase activity showed a latent but sustained pattern. Elevation of Erk1 and Erk2 protein levels was observed simultaneously. RT-PCR results demonstrated that the elevation of Erk protein level in BMP-2 induced cells was from the upregulation of mRNA expression. Furthermore, upregulated Erk proteins present enhanced phosphorylation. By using a dominant-negative Erk2 cell line, we demonstrated that nonfunctional Erk2 partially eliminated BMP-2 induced cell proliferation and ALP activity in the C3H10T1/2 cell. These results indicate that Erk is involved in BMP-2 induced osteoblast differentiation. The results also demonstrate that a latent and sustained signaling pattern exists in BMP induced signaling cascade.

Effect of bone morphogenetic protein-12 gene transfer on mesenchymal progenitor cells

Recombinant adenovirus mediated human bone morphogenetic protein-12 gene transfer induced tendon and cartilage-like tissue formation in vivo. The recombinant adenovirus with the human bone morphogenetic protein-12 gene was constructed, and mature human bone morphogenetic protein-12 expression mediated by adenovirus gene transfer was detected by specific antibody. Unlike bone morphogenetic protein-2 gene transfer, bone morphogenetic protein-12 gene transferred mesenchymal progenitor cell line C3H 10T1/2 showed no change of alkaline phosphatase activity, which is the mark of cell differentiation into osteoblastic phenotype. Injection of bone morphogenetic protein-12 gene transferred C3H 10T1/2 cells into nude mice thigh muscles induced tendon and cartilage-like tissue formation. The results indicate bone morphogenetic protein-12 has different effects on mesenchymal progenitor cell differentiation, and it may influence the cell differentiation into a nonosteoblast lineage.

Effects of physisorption of xenon on the thermal conductivity of resorcinol-formaldehyde aerogels

The effects of adsorption of xenon to the thermal conductivity of a resorcinol-formaldehyde aerogel were investigated in a temperature range from 20 to 120 K. It was found that at temperatures below 75 K, the adsorbed xenon has little effect on the thermal conductivity. Rapid rises of the thermal conductivity develop at temperatures around 75-80 K with magnitudes roughly proportional to the amount of xenon adsorbed. The effect is explained as due to adsorbed xenon atoms that enhance the neck connection between aerogel particles.

Expression of alpha-1 proteinase inhibitor in human islet microvascular endothelial cells

There is a microcirculation system within the islets of Langerhans. However, little is known about the phenotypic and functional characterization of islet microvascular endothelial cells (MVEC). In this study, we purified MVEC from human pancreatic islets by using Ulex europaeus (Sigma, St. Louis, MO) agglutinin-1 (UEA-1)-coated dynabeads (Dynal A.S., Oslo, Norway). These purified human islet MVEC (HI-MVEC) express von Willebrand factor, take up high levels of acetylated LDL, and upregulate endothelial cell leukocyte adhesion molecule 1 in response to tumor necrosis factor-alpha. Ultrastructure examination shows the presence of microvilli and fenestrations on the cell surface, Weibel-Palade bodies in the cytoplasm, and tight junctions between cells. Furthermore, we show that vascular endothelial cell growth factor contributes to the formation of surface fenestrations on cultured HI-MVEC. After purification, HI-MVEC exhibit a very low proliferation capacity and are strongly resistant to trypsin, compared with other original MVEC. We also demonstrate that alpha-1 proteinase inhibitor (Api) is expressed on HI-MVEC and specifically located at the area of cell-cell junctions. By reverse transcription-polymerase chain reaction, a significant messenger RNA band of Api was found only in HI-MVEC, but not in other organ-derived MVEC, indicating that expression of Api is islet MVEC specific. Antibodies to Api significantly reversed the resistance to trypsin and promoted proliferation of HI-MVEC, suggesting that these specific functional characteristics of HI-MVEC are related to the expression of Api. These results indicate that HI-MVEC exhibit some specific morphological and functional characteristics that differ from MVEC derived from other organs.

Congenital acute megakaryoblastic leukemia (M7) with chromosomal t(1;22)(p13;q13) translocation in a set of identical twins

Chromosomal translocations at t(1;22)(p13;q13) have been reported to occur in a number of infants with acute megakaryoblastic leukemia. A set of female twins with acute megakaryoblastic leukemia are reported with this unique translocation of 1p13 to 22q13. The twins presented at 2 months of age with fever and poor feeding and subsequently developed progressive hepatosplenomegaly. One twin died before treatment could be started; the other became septicemic 5 days after initiation of chemotherapy and eventually died.

Interferon-beta inhibits activated leukocyte migration through human brain microvascular endothelial cell monolayer

Perivascular leukocyte infiltration into the central nervous system is characteristic of multiple sclerosis (MS) pathology. Interferon-beta (IFN-beta) has shown efficacy in the treatment of patients with MS, but the relevant mechanisms remain incompletely understood. In this study the effects of IFN-beta on leukocyte transendothelial migration were investigated using cells relevant to MS pathogenesis, namely human brain microvascular endothelial cells (HB-MVEC). Activated, but not resting leukocytes exhibited a high transendothelial migration capacity. HB-MVEC prestimulated with tumor necrosis factor (TNF) and IFN-gamma significantly promoted leukocyte transendothelial migration. IFN-beta inhibited the activated leukocyte transendothelial migration on TNF/IFN-gamma-activated HB-MVEC in a dose-dependent manner. A matrix metalloproteinase (MMP) inhibitor and monoclonal antibodies to lymphocyte function antigen-1 (LFA-1) or intercellular adhesion molecule-1 (ICAM-1), but not to very late antigen-4 or to vascular cell adhesion molecule-1 significantly inhibited the transendothelial migration of stimulated leukocytes, suggesting that this phenomenon involves the LFA-1/ICAM-1 interaction and MMP. However IFN-beta did not interfere with the binding of leukocytes to HB-MVEC unless IFN-beta was preincubated with leukocytes or added to HB-MVEC at the time of stimulation. Furthermore IFN-beta did not modulate the expression of adhesion molecules on either stimulated leukocytes or activated HB-MVEC, but partially reduced TNF and interleukin-1 production from stimulated leukocytes during coculture with HB-MVEC. Interestingly, in the presence of IFN-beta, a significant down-regulation of MMP-9 release from stimulated leukocytes was found, especially for the activated form of MMP-9. These results indicate that inhibition of leukocyte transendothelial migration is an important mechanism accounting for the beneficial effects of IFN-beta in the treatment MS patients.

Enantioselective binding of an 11-cis-locked cyclopropyl retinal. The conformation of retinal in bovine rhodopsin

[formula: see text] The conformation of the retinal chromophore in rhodopsin is central for understanding the visual transduction process. The absolute twist around the 12-s bond of the chromophore in rhodopsin has been determined by studies with 11-cis-locked 11,12-cyclopropylretinal analogues (11S,12R)-2 and (11R,12S)-3, enantioselectively synthesized with the aid of an enzyme. The finding that enantiomer 2 binds to opsin while the other 3 does not defines the absolute sense of twist around the 12-s bond.