Transcytosis of payloads that are non-covalently complexed to bispecific antibodies across the hCMEC/D3 blood-brain barrier model

A transcellular shuttle system was generated for the delivery of non-covalently linked payloads across blood-brain barrier (BBB) endothelial cells. Transcytosis-enabling shuttles are composed of bispecific antibodies (bsAbs) that simultaneously bind transferrin receptor (TfR) and haptens such as digoxigenin or biocytinamide. Haptenylated payloads are attached to these vehicles via non-covalent hapten-antibody complexation. This enables targeting to and internalization into human BBB-derived microvascular endothelial hCMEC/D3 cells. In contrast to other shuttles, this system does not require special affinities or formats of their TfR-binding moieties for transcytosis and subsequent release. Non-covalent payload complexation to bsAb is flexible and robust, works for a multitude of payloads and enables separation of payloads from shuttles during transcytosis. Released payloads can enter the brain without connected bsAb entities, minimizing potential interference with distribution or functionality. Intracellular separation of shuttle and payload and recycling to cell surfaces may also enable recharging of the cell-bound BBB shuttle with payload for subsequent (merry-go-round) transport cycles.

Quantification of cell surface proteins with bispecific antibodies

Flow cytometry is an established method for fast and accurate quantitation of cellular protein levels and requires fluorescently labeled antibodies as well as calibration standards. A critical step for quantitation remains the production of suitable detection antibodies with a precisely defined ratio of antigen-binding sites to fluorophores. Problems often arise as a consequence of inefficient and unspecific labeling which can influence antibody properties. In addition, the number of incorporated fluorophores necessitates a special normalization step for quantitation. To address these problems, we constructed different mono- and bivalent bispecific antibodies with binding site(s) for the cell surface antigens, cMET, EGFR1/HER1, ErbB2/HER2 or ErbB3/HER3 and with an additional digoxigenin-binding single-chain Fv fusion. The fluorophore Cy5 was covalently coupled to digoxigenin and quantitatively bound by the bispecific antibody. A panel of tumor cell lines was assessed under different culture conditions for absolute receptor expression levels of the indicated antigens and the data were set in relation to mRNA, gene count and immunoblot data. We could reproducibly quantify these receptors, omit the otherwise required normalization step and demonstrate the superiority of a 1 + 1 bispecific antibody. The same antibodies were also used to quantify the number of proteins in intracellular vesicles in confocal microscopy. The antibodies can be stored like regular antibodies and can be coupled with different digoxigenin-labeled fluorophores which makes them excellent tools for FACS and imaging-based experiments.

Vesselplasty: a new minimally invasive approach to treat pathological vertebral fractures in selected tumor patients - preliminary results

PURPOSE

To evaluate the effectiveness and safety of percutaneous vesselplasty in pathological vertebral fractures of the thoracolumbar spine in selected tumor patients.

MATERIALS AND METHODS

Eleven pathological vertebral fractures in nine patients were treated with vesselplasty (Vessel-X®, MAXXSPINE). Nine of eleven vertebras (81.8 %) had major posterior wall deficiency (> 30 %). Clinical and radiological (CT) measures were obtained before and 3 months after the procedure.

RESULTS

The mean VAS improved significantly from preoperative to postoperative (6.9 ± 2.2 to 3.7 ± 2.3; p < 0.05), as did the ODI (59.7 %± 19.2 % to 40.3 %± 24.0 %; p < 0.05). The physical component summary of the SF-36 was significantly improved by the operation (19.2 ± 8.0 to 31.0 ± 16.5; p < 0.05). Symptomatic cement leakage or other operation-associated complications were not observed. Three patients were primarily treated with concomitant minimally invasive stabilization via fixateur interne. One patient had to undergo minimally invasive stabilization via fixateur interne 4 months after vesselplasty due to further collapse of the treated vertebral body.

CONCLUSION

From these preliminary results, vesselplasty appears to be a treatment option worth considering in pathological vertebral fractures, even in the case of posterior wall deficiency. Selected tumor patients might benefit from vesselplasty as a minimally invasive procedure for stabilization of the fractured vertebra, pain control, and improvement in body function and quality of life. Long-term prospective studies with a larger sample size are required to validate these results.

GHB-Induced Cognitive Deficits During Adolescence and the Role of NMDA Receptor

We have earlier reported that γ-hydroxybutyric acid (GHB) disrupts the acquisition of spatial learning and memory in adolescent rats. GHB is known to interact with several neurotransmitter systems that have been implicated in cognitive functioning. The N-methyl-D-aspartate receptor (NR) -type of glutamate receptor is considered to be an important target for spatial learning and memory. Molecular mechanisms governing the neuroadptations following repeated GHB treatment in adolecent rats remain unknown. We examined the role of NMDA receptor in adolescent GHB-induced cognitive deficit. Adolescent rats were administered with GHB on 6 consecutive days, and surface-expressed NMDA receptor subunits levels were measured. GHB significantly decreased NR1 levels in the frontal cortex. Adolescent GHB also significantly reduced cortical NR2A subunit levels. Our findings support the hypothesis that adolescent GHB-induced cogntive deficits are associated with neuroadaptations in glutamatergic transmission, particulaly NR functioning in the frontal cortex.

Efficacy and Frequency of Cerebrospinal Fluid Drainage in Operative Management of Thoracoabdominal Aortic Aneurysms

BACKGROUND

Paraplegia remains the most dreaded complication following thoracoabdominal aortic repair. We investigated the efficacy of cerebrospinal fluid drainage as a spinal cord-protecting modality. We also evaluated the correlation between the frequency of cerebrospinal fluid drainage and the Crawford classification.

METHODS

Spinal cord function was monitored during 20 open surgical procedures (group I) and 27 stent-graft implantations (group II). Evoked potentials and intracranial pressure were monitored in each operation. If intracranial pressure exceeded 15 mmHg, cerebrospinal fluid was drained.

RESULTS

Cerebrospinal fluid drainage was necessary in 75 % of patients in group I (Crawford type I: 33 %, type II: 40 %, type III: 20 %, type IV: 7 %) and in 22 % of patients in group II (Crawford type I: 33 %, type II: 66 %). Evoked potential alterations correlated with an increase in intracranial pressure. Timely cerebrospinal fluid drainage reversed these changes in 72 %. Three patients remained paraplegic.

CONCLUSION

Cerebrospinal fluid drainage is a valuable neuroprotective interventional tool to lower the risk of spinal cord ischemia. The combination of neurophysiological monitoring and cerebrospinal fluid drainage optimizes the prevention of paraplegia during aortic repair.

Thoracoabdominal Aortic Aneurysm Repair: Interplay of Spinal Cord Protecting Modalities

BACKGROUND

The purpose of this study was to assess the complementary use of different methods of measuring spinal cord perfusion during thoracoabdominal aortic surgery.

METHODS

The spinal cords of 28 patients undergoing surgery on the thoracoabdominal aorta were monitored with transcranial electrical stimulation (tcMEP) and somatosensory-evoked potentials (SSEP). Available approaches of spinal cord-protection included: Moderate systemic hypothermia, constant cerebrospinal fluid (CSF) drainage and pressure monitoring, reimplantation of segmental arteries, cardiopulmonary bypass (CPB), and staged clamping.

RESULTS

Fourteen of 19 patients (75%) undergoing open surgical treatment (Group I) exhibited loss of tcMEP after proximal aortic clamping. In nine cases (47%), we observed recovery of tcMEP after intraoperative interventions, while two patients subsequently developed paraplegia and three died. Seventeen of 19 patients showed loss of SSEP, with recovery in 12 cases (63%). During stent-graft implantation (Group II), one of nine patients (11%) demonstrated tcMEP loss with intraoperative, intervention-related recovery. The SSEP-recording course remained stable.

CONCLUSIONS

tcMEP/SSEP monitoring has proved to be an excellent means of detecting spinal cord ischaemia during surgery on thoracoabdominal aortic aneurysms. The prognostic value of tcMEP monitoring should be considered superior to that of SSEP measurements, because of its direct and rapid response to spinal malperfusion. Through combined neurophysiological monitoring, vital parameter balancing and intraoperative interventions, spinal cord perfusion improves and recovery of tcMEP and SSEP is achievable, reducing the prevalence of postoperative paraplegia.

Setup of Neurophysiological Monitoring with tcMEP/SSEP During Thoracoabdominal Aneurysm Repair

OBJECTIVES

The article describes a procedure for the intraoperative neurophysiological placement of electrodes to control the spinal cord function during thoracoabdominal aortic aneurysm repair.

MATERIAL AND METHODS

Intraoperative monitoring is performed by motor-evoked myogenic potentials after transcranial electric stimulation (tcMEP) and somatosensory-evoked potentials (SSEP). In tcMEP, the stimulating percutaneous needle electrodes are placed at C3 and C4 according to the 10 - 20 system for EEG recordings. TcMEP are recorded from the anterior tibial and gastrocnemius muscles on both sides. The SSEP electrodes are placed laterally and caudally onto the malleolus medialis in order to stimulate the tibial nerve. The stimulus is documented via electrodes attached to the scalp within the sensory cortex region.

RESULTS

The application of the electrodes is both easy to learn and can be performed without further difficulties. Once attached, the electrodes provide a quick assessment and interpretation of spinal cord function. The identification of external sources of disturbance during the monitoring (e. g. insufficient impedance, unfavourable electrode positioning, and technical interference caused by medical equipment) enables the supervisor to differentiate between normal and abnormal neurological responses.

CONCLUSIONS

TcMEP and SSEP allow an adequate, direct, and reliable intraoperative assessment of spinal cord function, enabling the surgeon to diagnose an impending ischaemia and act accordingly. This measurement technique provides the surgical team with a means of integrating neurological aspects during thoracoabdominal aneurysm repair.

Postnatal stress selectively upregulates striatal N-methyl-D-aspartate receptors in male rats

Early life events have been thought to contribute towards vulnerability to drug addiction later in life. In the present investigation, the effect of daily neonatal maternal isolation stress on NMDA channel activity was studied. [3H]MK-801 binding was measured in several brain regions from neonatally isolated (ISO) and nonhandled (NH) adult male and female rats. Maximal [3H]MK-801 binding in the caudate-putamen of male ISO rats was 58% higher compared to same sex NH rats. Unlike male rats, maximal [3H]MK-801 binding in the caudate-putamen of female ISO rats was lower than female NH rats. No other brain region showed any significant difference in maximal [3H]MK-801 binding between ISO and NH male and female rats, respectively. There was no effect of pup isolation on the binding affinity (K(d) value) in either sex. Repeated maternal isolation is associated with alterations in the NMDA channel activity in the caudate-putamen of adult rats, and may be responsible for the augmentation in the addictive behavior reported.

Effect of melatonin on cocaine-induced behavioral sensitization

Melatonin, a pineal hormone and a potent free radical scavenger with neuroprotective actions, has been reported to act as an inhibitor of nitric oxide synthase (NOS). We have earlier shown that inhibitors of NOS (N(omega)-nitro-L-arginine methyl ester [L-NAME], 7-nitroindazole [7-NI]) block cocaine-induced behavioral sensitization. In the present study, the effects of melatonin on cocaine behavior were studied. A single injection of melatonin markedly augmented cocaine-induced locomotor activity. Rats injected daily with melatonin prior to cocaine injections failed to elicit cocaine sensitization. These behavioral effects of melatonin do not completely mimic those of other NOS inhibitors, suggesting that the effects of melatonin on cocaine behavior are mediated by both NOS-dependent as well as NOS-independent mechanisms.

Developmental maturation of the N-methyl-D-aspartic acid receptor channel complex in postnatal rat brain

The N-methyl-D-aspartate (NMDA) receptor plays an important role in developmental plasticity. Previous studies have reported differences between the NMDA receptor-channel complex in the rat pup brain and the adult brain. In the present study, modulation of the NMDA channel complex as a function of age was measured to determine when the temporal switching of the NMDA receptor from the immature form to the adult mature form takes place. [(3)H]MK-801 binding was measured in the rat forebrain from postnatal day 1 to day 21. Our data suggest the presence of two types of NMDA receptors - an immature type and a mature type. The immature NMDA receptor, seen during the early postnatal period (day 1-day 14) is highly sensitive to spermidine, L-glutamate alone potentiates [(3)H]MK-801 binding, and glycine failed to potentiate an L-glutamate-induced increase in [(3)H]MK-801 binding. During the late postnatal period (after day 14) spermidine alone did not increase [(3)H]MK-801 binding as potently as it did during the early postnatal period, high-affinity [(3)H]MK-801 binding was not seen in the presence of L-glutamate alone, and L-glutamate and glycine or L-glutamate and spermidine or L-glutamate, glycine and spermidine together, significantly increased [(3)H]MK-801 binding in a manner similar to that reported in the adult brain. Together, the pharmacology of the NMDA receptor during the early postnatal period differs from the adult-like receptor seen during the late postnatal period, and that in rats the apparent switching of the NMDA receptor from the immature type to the mature type takes place after the second postnatal week.

Characterization of a chimeric T-cell receptor with specificity for the Hodgkin's lymphoma-associated CD30 antigen

Recombinant receptors with antibody-like specificity for tumor-associated antigens were shown to direct specifically T cells to target tumor cells. Hodgkin and Reed-Sternberg cells, the malignant cell population in Hodgkin's lymphoma, express high amounts of the cell surface antigen CD30. An anti-CD30 T-cell receptor with cellular activation properties is expected to graft T cells with specificity to Hodgkin cells. Here, the authors characterize a chimeric T-cell receptor with an extracellular domain consisting of the single-chain antibody fragment HRS3-scFv with specificity for the CD30 antigen and intracellular domain of the signal transducing part of the Fc-epsilon-I-gamma receptor. The HRS3-scFv was derived from the monoclonal anti-CD30 antibody HRS3 and retained specificity for the CD30 antigen. The recombinant HRS3-scFv-gamma receptor was expressed under control of the RSV-LTR after transfection into MD45 T-cells. The chimeric receptor protein is detected and analyzed by enzyme-linked immunosorbent assay (ELISA) and immunoprecipitation. Expression of the chimeric receptor converts MD45 T cells to specificity for CD30+ lymphoma cells. Specific cross-linking of the chimeric receptor with antigen resulted in cytolytic reactivity against CD30+ tumor cells in vitro. The results demonstrate that the chimeric receptor HRS3-scFv-gamma converts T cells to a specific MHC-unrestricted cytolytic response against CD30+ tumor cells offering an alternative strategy in cellular immunotherapy of Hodgkin's disease.

Female gonadal hormones differentially modulate cocaine-induced behavioral sensitization in Fischer, Lewis, and Sprague-Dawley rats

Evidence suggests the existence of genetic differences in cocaine sensitization in male rats. The present study was undertaken to investigate cocaine sensitization in female rats of genetically distinct inbred (Fischer 344 and Lewis) and outbred (Sprague-Dawley) strains. All female rats were bilaterally ovariectomized and randomly assigned to one of four experimental groups: 1) estradiol benzoate group, 2) progesterone group, 3) estradiol benzoate-plus-progesterone group, and 4) ovariectomized group. Additional controls included sham-operated female rats, female rats that received a single oil injection, and female rats that received repeated oil injections. To determine gender-related differences in the acute and chronic effects of cocaine, data obtained from female rats were compared with those from strain- and weight-matched male rats. Estradiol benzoate-plus-progesterone female rats showed greater locomotor effect in response to an acute dose of cocaine and had more robust sensitization in response to repeated cocaine than did male rats. The bilateral removal of ovaries abolished cocaine sensitization. In all strains of rats studied, progesterone alone did not alter the ovariectomy-induced attenuation of cocaine behavior, but estrogen alone restored cocaine-induced behavioral sensitization. There were significant strain effects on the degree of gonadal hormonal-induced modulation of cocaine sensitization in female rats. Female Lewis rats were extremely sensitive to repeated-cocaine effects, whereas the Fischer 344 female rats showed only marginal effects. The Sprague-Dawley rats ranked intermediate in their behavioral sensitivity. The present study strongly supports the hypothesis that female rats are more sensitive to both acute and chronic behavioral effects of cocaine than are male rats and that the effects are strain dependent. It also shows that estrogen plays an important role in the increased sensitivity of female rats to cocaine sensitization. Together, these data indicate significant interactions between ovarian steroid hormones and genetic factors in cocaine-induced behavioral effects.

A chimeric receptor that selectively targets membrane-bound carcinoembryonic antigen (mCEA) in the presence of soluble CEA

Chimeric T cell receptors with specificity for tumor-associated antigens are successfully used to target T cells to tumor cells. The efficacy of this approach, however, is reduced by soluble antigen that is frequently present in high serum concentrations. To overcome this situation, we constructed an anti-CEA chimeric receptor whose extracellular moiety is composed of a humanized single chain antibody fragment (scFv) derived from the anti-CEA mAb BW431/26 and the CH2/CH3 constant domains of human IgG. The intracellular moiety consists of the gamma-signaling chain of the human Fc epsilon RI receptor constituting a completely humanized chimeric receptor. After transfection, the humBW431/26 scFv-CH2CH3-gamma receptor is expressed as a homodimer on the surface of MD45 T cells. Co-incubation with CEA+ tumor cells specifically activates grafted MD45 T cells indicated by IL-2 secretion and cytolytic activity against CEA+ tumor cells. Notably, the efficacy of receptor-mediated activation is not affected by soluble CEA up to 25 micrograms/ml demonstrating the usefulness of this chimeric receptor for specific cellular activation by membrane-bound CEA even in the presence of high concentrations of CEA, as found in patients during progression of the disease.

Generation of the single chain antibody fragment conserves the idiotypic profile of the anti-CD30 monoclonal antibody HRS3

Recombinant single chain antibody fragments (scFv) derived by combining immunoglobulin VL and VH regions provide valuable antibody-like reagents. A number of them are shown to have retained the antigen specificity of the parental monoclonal antibody (MoAb). Little is known about the idiotypic profile of scFv fragments compared with that of the parental MoAb. To address this question we analysed the idiotypic profile of a scFv that was derived by phage-display techniques from the anti-CD30 MoAb HRS3. We assayed (i) binding of HRS3-scFv to recombinant CD30-Fc antigen and to four different anti-idiotypic MoAbs defining at least three different idiotopes on HRS3, and (ii) cross-competition with the parental MoAb HRS3 and the closely related anti-CD30 MoAb HRS4. The assays revealed that the HRS3-scFv fragment exhibits the same specificity for both CD30 antigen and the tested anti-idiotypic MoAbs compared with the parental MoAb demonstrating that the recombinant scFv fragment has retained the complete idiotope of the parental MoAb.

Isolation of single chain antibody fragments with specificity for cell surface antigens by phage display utilizing internal image anti-idiotypic antibodies

Recombinant single chain antibody fragments (scFv) with specificity for membrane-bound antigens can be isolated by phage display techniques. The strategy involves selection of recombinant phage antibodies by binding to cells expressing the respective antigen. This results frequently in high nonspecific adherence of phages to cellular membranes. To resolve the problem we have made use of an internal image anti-idiotypic antibody mimicking the membrane-bound CD30 antigen and successfully isolated scFv fragments with specificity for CD30. The cDNA coding for the immunoglobulin heavy and light chain variable regions of the anti-CD30 monoclonal antibody (mAb) HRS3 was expressed by phage display techniques. Recombinant HRS3-scFv phages were efficiently enriched by one cycle of panning on the internal image anti-idiotypic mAb 9G10. The isolated HRS3-scFv clone retained the binding specificity of the parental mAb HRS3 to the internal image anti-idiotypic mAb 9G10 as well as to an anti-idiotypic mAb without the internal image. Furthermore HRS3-scFv reacted with recombinant and cell-bound CD30 antigen, respectively. Binding of scFv fragments to anti-idiotypic mAbs will provide a versatile strategy for the efficient isolation of recombinant antibody fragments.

Chimeric anti-TAG72 receptors with immunoglobulin constant Fc domains and gamma or zeta signalling chains

We recently described the generation and expression of a chimeric T cell receptor with specificity for the tumor antigen TAG72 consisting of the single chain antibody (scFv) B72.3-scFv and the gamma chain of the FcepsilonRI receptor. The corresponding chimeric receptor containing the zeta chain of the TCR as signalling unit is not functionally expressed reflecting that the requirements for functional expression of chimeric receptors containing the gamma signalling chain are apparently different compared to those containing the CD3zeta signalling chain of the TCR. We describe a novel set of chimeric anti-TAG72 receptors including in their extracellular moiety the constant immunoglobulin CH2/3 domains that allow stable expression of chimeric gamma as well as zeta receptors. We designed anti-TAG72 receptors that consist of a scFv fragment derived from an anti-TAG72 second generation antibody (CC49) and of the CH2/3 domains of the human IgG and intracellularily either of the zeta or gamma signalling chain. The recombinant CC49-CH2/3-zeta and CC49-CH2/3-gamma DNA, respectively, was transfected into MD45 T cells and expressed under control of the RSV LTR. Both receptors were found on the cell membrane of transfected cells as demonstrated by flow cytometry analysis using an anti-human IgG Fc antibody directed to the CH2/3 immunoglobulin domains of the chimeric receptor. Specific cross-linking of the chimeric zeta as well as the gamma receptor by antigen or anti-human Ig antibodies resulted in specific activation of transfected cells. Our results demonstrate that both the gamma chain and the zeta chain++ containing receptor are stably expressed and convert T cells to specificity for the TAG72 antigen. This receptor design will facilitate efficient generation of genetically modified peripheral T cells and may provide valuable tools for the cellular immunotherapy of TAG72+ tumors.

Repeated neonatal phencyclidine treatment impairs performance of a spatial task in juvenile rats

The present study was designed to determine whether repeated postnatal blockade of N-methyl-D-aspartate (NMDA) channel produces cognitive deficit in juvenile rats. Rats receive phencyclidine (PCP) intraperitoneally (i.p.) from postnatal Day 5 and continued daily till Day 15. On Day 28, saline- and PCP-treated rats were trained in the Morris water maze task. PCP-treated rats performed as well as the saline-treated rats on the first day of testing, but on the second day of testing they did significantly poorly compared to saline-treated controls. These data suggest that chronic postnatal NMDA channel blockade by PCP impairs processes that enable rats to retain spatial information.

An anti-CD30 chimeric receptor that mediates CD3-zeta-independent T-cell activation against Hodgkin's lymphoma cells in the presence of soluble CD30

Hodgkin's lymphoma patients fail to establish an efficient cellular response against CD30+ Hodgkin/Reed-Sternberg cells. An impaired T-cell receptor/CD3-zeta-mediated activation of T cells is thought to be involved in this situation. We here present a chimeric anti-CD30 receptor that mediates MHC and T-cell receptor/CD3-zeta-independent T-cell activation against CD30+ lymphoma cells even in the presence of soluble CD30. The receptor consists of the binding domain of the monoclonal antibody HRS3 and the signaling unit of the Fc epsilonRI-receptor gamma-chain. After expression in MD45 T cells, receptor cross-linking with immobilized anti-idiotypic monoclonal antibody and CD30+ cells, respectively, results in increased interleukin 2 secretion and specific cytolysis of CD30+ Hodgkin's lymphoma cells. Soluble CD30 in concentrations up to 6000 units/ml did not interfere with cellular activation induced by membrane-bound antigen. This demonstrates the feasibility of the chimeric anti-CD30-scFv-gamma receptor in CD30+ lymphoma cell targeting, even in the presence of as high concentrations of soluble CD30 as are found in patients during progression of the disease.

T cell targeting of TAG72+ tumor cells by a chimeric receptor with antibody-like specificity for a carbohydrate epitope

BACKGROUND & AIMS

Chimeric receptors with specificity for defined tumor antigens are valuable tools for targeting cytolytic T cells specifically to tumor cells. The aim of this study, for the situation of gastrointestinal cancer, was to investigate the generation of a chimeric T cell receptor that specifically binds the tumor antigen TAG72 (CA72-4) and transmits a signal for cellular activation.

METHODS

A single-chain antibody (scFv) was derived from the monoclonal anti-TAG72 antibody B72.3 by phage display techniques (B72.3-scFv) and fused to the signaling unit of the Fc epsilon-RI receptor gamma chain, resulting in a chimeric signaling receptor, B72.3-scFv-gamma.

RESULTS

The B72.3-scFv and the chimeric B72.3-scFv-gamma receptor bound specifically to the TAG72 antigen. After transfection, T cells expressing the chimeric B72.3-scFv-gamma specifically recognized TAG72 positive cells. Cross-linking of the chimeric receptor with antigen resulted in interleukin 2 release and cytolytic activity against TAG72 positive tumor cells in vitro.

CONCLUSIONS

T cells equipped with the chimeric anti-TAG72 receptor can be specifically activated to target and lyse TAG72 positive gastrointestinal tumor cells.

Specific activation of resting T cells against CA19-9+ tumor cells by an anti-CD3/CA19-9 bispecific antibody in combination with a costimulatory anti-CD28 antibody

Specific activation of resting lymphocytes for tumor targeting can be achieved by bispecific monoclonal antibodies (bi-mAb) with specificity for tumor antigens and T-cell-activating antigens, respectively, in combination with a costimulatory anti-CD28 antibody. We describe the generation and function of a bi-mAb with specificity for CD3 and for the tumor antigen CA19-9. The bi-mAb OKT3/NSI19-9 was generated by somatic fusion of two hybridoma lines secreting antibodies against CA19-9 and CD3, respectively. A hybrid/hybridoma was established, and its bi-mAb was characterized. In combination with a costimulatory anti-CD28 mAb resting peripheral lymphocytes could be activated specifically with T-cell proliferation and secretion of high amounts of interferon-gamma. On specific T-cell activation, bi-mAb OKT3/NSI19-9 could also redirect the cytotoxic effects of these T cells toward CA19-9+ tumor cells in vitro. Our results indicate that specific activation of resting T cells with bi-mAb OKT3/NSI19-9 in combination with an anti-CD28 mAb can activate resting T cells specifically and leads to antigen-dependent bi-mAb-mediated cytotoxicity against CA19-9+ target cells. This approach may offer new perspectives for the specific immunotherapy of CA19-9+ tumors.

Specific activation of resting T cells against tumour cells by bispecific antibodies and CD28-mediated costimulation is accompanied by Th1 differentiation and recruitment of MHC-independent cytotoxicity

Specific activation of resting lymphocytes for tumour targeting can be achieved by bispecific monoclonal antibodies (bi-MoAbs) with specificity for tumour antigens and T cell-activating antigens in combination with a costimulatory anti-CD28 antibody. In this study we focus on the immunomodulatory function of an anti-CD3/CA19-9 bi-MoAb in combination with a costimulatory anti-CD28 antibody which may result not only in antigen-specific, T cell-mediated tumour cell lysis but also in recruitment of other cellular effector functions. In combination with costimulatory anti-CD28 antibodies, resting peripheral lymphocytes could be activated specifically to secrete high amounts of Th1 cytokines (IL-2, interferon-gamma (IFN-gamma)) characterizing a cellular immune response. In contrast, no IL-4 and only low amounts of IL-10 could be detected. Furthermore, bi-MoAb-mediated CA19-9-specific activation of T cells was accompanied by recruitment of MHC- and CA19-9-independent cytotoxicity, as was determined by lysis of different CA19-9-cell lines. This MHC-independent cytotxicity was mediated at least in part by activated natural killer (NK) cells, as depletion of CD16+ NK cells resulted in substantial decrease of cytotoxicity against CA19-9- targets. Our results indicate that specific activation of resting T cells with CD3-associated bi-MoAbs in combination with an anti-CD28 antibody leads to a Th1 differentiation pathway and is accompanied by recruitment of MHC-independent lymphokine-activated killer (LAK) cell cytotoxicity which can possibly be directed against a heterogeneous tumour.

Effects of nitric oxide synthase inhibitors on cocaine sensitization

Behavioral sensitization to cocaine was tested for in rats pretreated with a nitric oxide (NO) synthase inhibitor, N omega-nitro-L-arginine methyl ester (L-NAME) or 7-nitro indazole (7-NI). A 5-day pre-exposure to once daily cocaine (15 mg/kg, i.p.) injections yielded sensitization to cocaine (15 mg/kg)-induced behavioral activation. Pretreatment injections of L-NAME (100 mg/kg) or 7-NI (30 mg/kg), administered 30 min before each cocaine pre-exposure injection, acutely inhibited cocaine-induced behavioral activation. No sensitization was found after L-NAME pretreatment in a protocol with a 3-day withdrawal between pre-exposure and test cocaine injections. With a 10-day withdrawal period, cocaine sensitization was prevented by L-NAME or 7-NI pretreatment. These results after a 10-day withdrawal are unlikely to arise from deficient brain NO synthase activity on the test day. Instead, these findings suggest a role for NO in mechanisms underlying the development of cocaine sensitization. We conclude that NO participates in both the development of sensitization as well as the expression of cocaine-induced behavior in previously drug-naive animals.

Postnatal phencyclidine treatment differentially regulates N-methyl-D-aspartate receptor subunit mRNA expression in developing rat cerebral cortex

The present study was designed to determine the effects of chronic neonatal exposure to the NMDA receptor antagonist phencyclidine (PCP) on [3H]MK-801 binding and on gene expression of NMDA receptor subunits in juvenile male rats. Rat pups were injected daily with PCP from day 5 to 15 and killed on day 21. [3H]MK-801 binding was measured by quantitative autoradiography. A sensitive RNase protection assay was employed to determine simultaneously the mRNA levels of NR1 subunit (comprising all different splice variants) and three NR2 subunits (NR2A-NR2C). The relative distribution profile of NMDA receptor subunits in the cerebral cortex was NR2B > NR1 > NR2A > NR2C and in the cerebellum NR2C = NR1 > NR2A = NR2B. Chronic PCP administration in postnatal rats produced significant reduction in both [3H]MK-801 binding and mRNA level of the NR2B subunit in the cerebral cortex. Expression of the other NMDA receptor subunits in the cerebral cortex did not change following the drug treatment. In the cerebellum, neither [3H]MK-801 binding nor any of the NMDA receptor subunit expression levels showed any alteration. Together, these data provide a molecular correlate for chronic postnatal PCP-induced down-regulation of [3H]MK-801 binding in rat cerebral cortex and suggest that the NR2B subunit plays an important role in developmental plasticity.

Antagonist of N-methyl-D-aspartate receptors partially prevent the development of cocaine sensitization

Behavioral sensitization to cocaine was tested for in rats pretreated with MK-801, a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, or D-3-(2-carboxypiperazin-4-yl)-1-propenyl-1-phosphonic acid (D-CPPene), a competitive NMDA antagonist. A 5-day regimen of once-daily cocaine (15 mg/kg) injections yielded sensitization to cocaine (15 mg/kg)-induced behavioral activation. Cocaine sensitization was partially prevented by MK-801 (0.25 mg/kg) or D-CPPene (20 mg/kg) pretreatment. These results differ from previous reports that NMDA receptor antagonists completely prevented the development of stimulant sensitization. While raising questions about methodological differences among laboratories studying this issue, our findings suggest that sensitization may involve mechanisms dependent on NMDA-receptor function as well as NMDA receptor-independent mechanisms.

Repeated postnatal phencyclidine administration in female juvenile rat delays onset of puberty but has no effect on pentylenetetrazol-induced seizure-susceptibility

The effects of chronic phencyclidine (PCP) treatment on sexual maturation and seizure-susceptibility in the developing female rat were studied. Postnatal female rats were injected once daily with 5 mg/kg PCP from Day 5 till Day 15 and were observed for sexual maturation--vaginal opening and estrus cyclicity were used as indices of sexual maturation. PCP-treated rats showed a delay in both vaginal opening and in estrus cyclicity compared to saline-treated pair-fed controls. On postnatal Day 21, PCP-treated rats and saline-treated controls were tested for seizure-susceptibility using the pentylenetetrazol (PTZ)-induced seizure paradigm. PCP-treated female rats did not differ from saline-treated controls in their susceptibility to PTZ-induced seizures. In conclusion, chronic PCP administration during development in female rats disrupts sexual maturation but has no short-term effect on seizure susceptibility.

Chronic postnatal phencyclidine treatment on [3H](+) pentazocine binding in juvenile rat brain

Chronic phencyclidine (PCP) administrations in postnatal rats produce long-term behavioral changes. Here we report the effects of repeated postnatal PCP treatment on [3H](+)pentazocine binding in juvenile rats. Saturation analyses of the binding data showed no significant difference in any of the binding characteristics between chronic PCP-related rats and saline-treated controls suggesting that mechanisms other than alterations in sigma1 binding underlie the behavioral effects of repeated postnatal PCP administration in immature rats.

Chronic neonatal phencyclidine treatment produces age-related changes in pentylenetetrazol-induced seizures

Although excitatory amino acids are known to play a critical role in the plasticity of developing brain, the behavioral effects of blocking the N-methyl-D-aspartate (NMDA) receptor-gated ion channel during development are not clear. Here we report the effects of chronic postnatal administration of 1-phenylcyclohexylpiperidine (phencyclidine or PCP), a NMDA channel blocker, on seizure susceptibility. To study the short-term effects of chronic PCP administration on pentylenetetrazol (PTZ)-induced seizures, rats were treated with PCP (5 mg/kg, i.p.) for 11 days from postnatal days 5-15, 24-34 or 44-54 and tested in the PTZ-induced seizure paradigm on postnatal days 21, 40 and 60, respectively. Administration of PCP in 5-15-day-old rats resulted in increased seizure susceptibility at day 21, while administration of PCP in postweanling rats (days 24-34) markedly attenuated their susceptibility to seizures at day 40. PCP injection had little effect on the seizure susceptibility of older rats. To study the long-term effects of postnatal PCP treatment, rats were injected with PCP (5 mg/kg from postnatal day 5-15, i.p.) and were tested for PTZ-induced seizures on postnatal days 40 and 60; each rat was tested only once. When tested for PTZ-induced seizure on day 40, PCP-treated rats did not differ from saline-treated controls. When tested on day 60, PCP-treated rats had a lower incidence of seizures and in the rats that did have seizures their latencies were significantly prolonged compared to controls. Together, our data suggest that chronic PCP administration alters PTZ-induced seizure susceptibility in an age-dependent manner and chronic PCP administration in postnatal rats produces long-term changes that persist into adulthood.

PCP/NMDA receptor-channel complex and brain development

Phencyclidine (PCP) acts on a variety of neurotransmitter systems--cholinergic, catechoaminergic, indoleaminergic, and peptidergic--but the dose at which it produces its psychotomimetic effects is lower than the concentration at which it affects these systems. At low doses, PCP interacts primarily with a binding site located within the ionophore associated with the NMDA receptor complex--binding to this site has been used as a biochemical marker for NMDA channel activity. PCP/NMDA receptor-channel complex has been shown to play an important role in brain development but little is known of the neurochemical effects following postnatal administration of NMDA antagonists in rats. In the present study, rats were treated with PCP from Day 5 until Day 15 after birth and binding to the PCP receptor was measured on postnatal Day 21 using [3H]MK-801; MK-801 is a more potent and specific ligand at the PCP receptor than PCP itself. Postnatal PCP administration produced specific alterations in PCP receptor binding in 21-day-old rat forebrain. There was a reduction in the high affinity component of [3H]MK-801 binding under baseline binding conditions. In the presence of both L-glutamate and glycine, [3H]MK-801 binding in PCP-treated rats increased significantly compared to baseline but did not differ from saline-treated controls. These findings suggest that chronic PCP administration in developing rats alter NMDA channel functioning which could have long-term neurobehavioral consequences.

Polyamine effects upon N-methyl-D-aspartate receptor functioning: differential alteration by glutamate and glycine site antagonists

Polyamines such as spermidine potentiate activation of the N-methyl-D-aspartate (NMDA)-type excitatory amino acid receptor. The goal of the present study was to investigate interactions between the putative polyamine binding site and previously described sites for glutamate and glycine. Binding of the high-potency PCP receptor ligand [3H]MK-801 to well-washed rat brain membranes was used as an in vitro probe of NMDA receptor activation. Spermidine concentration-response studies were performed in the absence and presence of both glutamate and glycine, with and without D-(-)-2-amino-5-phosphonovaleric acid (D(-)-AP-5) or 7-chlorokynurenic acid (7Cl-KYN). Incubation in the presence of spermidine alone induced a 20.4-fold increase in [3H]MK-801 binding with an EC50 value of 13.3 microM. The mean concentration of spermidine which induced maximal stimulation of binding was 130 microM (n = 10, S.E.M. = 24.66, range = 25-250 microM). Glutamate (10 microM) decreased the EC50 value for spermidine-induced stimulation of [3H]MK-801 binding to 3.4 microM. Glycine (10 microM) did not significantly alter either maximum spermidine-induced [3H]MK-801 binding or the EC50 value for spermidine-induced stimulation of [3H]MK-801 binding. Incubation in the presence of the specific glutamate antagonist D(-)AP-5 attenuated [3H]MK-801 binding in a glutamate-reversible fashion. The competitive glycine antagonist 7Cl-KYN decreased maximum spermidine-induced [3H]MK-801 binding in a glycine-reversible fashion. In addition, 7Cl-KYN increased the EC50 value for spermidine-induced stimulation of [3H]MK-801 binding while D(-)AP-5 was without effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Kinetic mechanisms of glycine requirement for N-methyl-D-aspartate channel activation

Glycine potentiates N-methyl-D-aspartate (NMDA) receptor-mediated responses via its interaction with a strychnine-insensitive glycine recognition site. We have previously shown that the potent glycine receptor antagonist 7-chlorokynurenic acid (7Cl-KYN) dose-dependently inhibits [3H]MK-801 binding to the PCP receptor and that this effect is reversed by glycine. [3H]MK-801 binding to the PCP receptor within the NMDA receptor-gated ion channel is a measure of channel activation. Association of PCP receptor ligands is biexponential with the fast component of binding serving as a marker of activated NMDA channels. In the present study we utilize 7Cl-KYN as a probe of the kinetic mechanism of the glycine effect upon NMDA receptor functioning. In the presence of L-glutamate, incubation with 7Cl-KYN completely abolished the fast component of [3H]MK-801 association in 4 out of 5 experiments. In the fifth experiment where the fast component was detected, it accounted for less than half of that seen in the presence of L-glutamate alone. 7Cl-KYN-induced inhibition of the fast component of [3H]MK-801 association was reversed by the addition of glycine. Since the fast component represents ligand binding to the PCP receptor via the open NMDA channel, selective reduction of this component by 7Cl-KYN indicates that glycine receptor antagonists reduce the probability of channel opening, and also that the selective reduction in the component of [3H]MK-801 binding that manifests fast kinetics can serve as a marker for glycine antagonists.

Glycine reverses 7-chlorokynurenic acid-induced inhibition of [3H]MK-801 binding

7-Chlorokynurenic acid (7-Cl KYNA) has been reported to attenuate N-methyl-D-aspartate (NMDA) receptor functioning by a potent and selective inhibitory action mediated at the strychnine-insensitive glycine recognition site of the NMDA complex. Here we report that 7-Cl KYNA dose-dependently inhibits [3H]MK-801 binding to the PCP receptor, and that this effect is reversed by addition of glycine. Since [3H]MK-801 binding is a measure of channel activation, our results are consistent with the hypotheses that 7-Cl KYNA exerts its NMDA receptor antagonism by acting at the glycine site, and that activation of the glycine site is required for NMDA channel activity to occur.

Direct method for detecting small quantities of hepatitis B virus DNA in serum and plasma using the polymerase chain reaction

Serum components inhibit DNA polymerase, thereby obviating direct detection of serum viral DNA sequences by the polymerase chain reaction (PCR). This has necessitated extraction of nucleic acid from sera before performing PCR and has resulted in loss of sensitivity. By adsorbing virus to a solid surface (microcentrifuge tubes or antibody coated microparticles) followed by proteinase K digestion, as little as three viruses per 200 microliters serum may be directly detected by PCR without nucleic acid extraction. The sensitivity is dependent on the surface area of the adsorptive surface and is increased by having antibodies on the adsorptive surface. The nucleic acid sequence of the amplified DNA fragments may be directly determined by the dideoxy method. Of 24 plasma samples from HBsAg+ volunteer blood donors, HBV DNA was detected in 7 by dot blot assay, 7 by liquid hybridization, and 9 by PCR. PCR detected DNA in every sample that was positive by another assay. Analysis of serial samples of two patients with acute self-limited hepatitis B found detectable HBsAg and pre-S2 antigenemia before HBV DNA by the PCR method. These results suggest that surface antigenemia may precede viremia during acute hepatitis.

The novel anticonvulsant MK-801: a potent and specific ligand of the brain phencyclidine/sigma-receptor

MK-801 (5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate) is a novel anticonvulsant agent reported to antagonize certain N-methyl-D-aspartate (NMDA)-mediated effects non-competitively. The question arises of the mechanism underlying the anti-NMDA and anticonvulsant effects of MK-801. In the present study MK-801 is shown to be an extremely potent inhibitor of the binding of N-[3H] (1-[2-thienyl]cyclohexyl)piperidine ([3H]TCP) to brain phencyclidine (PCP)/sigma-receptors. Its IC50 value of 3.8 +/- 0.8 nM in this assay ranks it as the most potent known ligand of brain PCP/sigma-receptors. Addition of MK-801 altered the apparent Kd but not the apparent Bmax values for [3H]TCP binding, indicating a competitive interaction. The specificity of action of MK-801 is supported by the finding that MK-801 strongly inhibited the binding of (+)-N-[3H]allylnormetazocine ((+)-[3H]SKF 10,047) to the PCP/sigma-receptor but its effect on (+)-[3H]SKF 10,047 binding to the non-PCP, haloperidol-sensitive sigma-binding site was weaker by several orders of magnitude. Furthermore, MK-801 exerts PCP-like antagonistic effects upon NMDA-induced [3H]norepinephrine release. These findings support the concept that the anticonvulsant and anti-NMDA effects of MK-801 result from its being the most potent known ligand of PCP/sigma-receptors.

Hepatitis B disease in dialysis and transplant patients. Further epidemiologic and serologic studies

As hepatitis B virus (HBV) infection in renal transplant recipients is associated with a high incidence of progressive liver disease it may be inadvisable to transplant hemodialysis patients with hepatitis B antigenemia. To determine the natural history of HBV disease in hemodialysis patients, all 49 patients on hemodialysis treatment for at least 1 year, at 3 centers, who developed circulating hepatitis B surface antigen (HBsAG), were studied. A subgroup of these patients (n = 31) aged less than or equal to 50 years, followed for 55 +/- 6 months after detection of HBsAg was compared with 22 previously studied HBsAg-positive transplant patients followed for 81 +/- 9 months. Significantly more transplant patients developed chronic hepatitis defined biochemically (P less than .001) and none of the transplant patients became HBsAg-negative compared with 19% of the hemodialysis group. Taking difference in follow-up into account, mortality was significantly higher in the transplant recipients (P less than .005) following development of HBsAg antigenemia, and the mortality difference was attributable to deaths from liver disease. A total of 36 serum samples from 14 of the 22 HBsAg-positive renal transplant recipients was analyzed for hepatitis B e antigen (HBeAg), antibody to hepatitis D virus (anti-HD), and hepatitis B virus deoxyribonucleic acid (HBVDNA) concentration. No serum sample was anti-HD-positive. Twelve of the 14 patients were HBeAg-positive. Five patients became HBeAg-negative, 3 of whom developed aggressive liver disease. One HBeAg-negative anti-HBe-positive patient had progression of liver disease from asymptomatic carrier status to chronic active hepatitis (CAH). Of 14 patients, 9 developed progressive CAH. HBVDNA concentration was not diagnostic of disease activity on liver biopsy. However only 1 sample of 10 measured in 5 patients with nonprogressive disease had a level greater than 100 pg/L, compared with 9 of 17 in the group who progressed to CAH. During the interval when the liver histology progressed from asymptomatic carriage or chronic persistent hepatitis (CPH) to CAH, the HBVDNA concentration increased by greater than 10 times baseline in 4 of 5 patients who had serial samples, whereas this did not occur in 4 patients with nonprogressive disease. We conclude that the long-term outcome of hepatitis B infection in transplant recipients is significantly worse than in hemodialysis patients. Therefore it may be inadvisable to transplant HBsAg-positive hemodialysis patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Non-competitive regulation of phencyclidine/sigma-receptors by the N-methyl-D-aspartate receptor antagonist D-(-)-2-amino-5-phosphonovaleric acid

D-(-)-2-Amino-5-phosphonovaleric acid (D(-)AP5), a selective, potent competitive antagonist of N-methyl-D-aspartate (NMDA)-type excitatory amino acid receptors was used to investigate the relationship between NMDA receptors and phencyclidine (PCP) binding. Incubation of rat brain membranes with D(-)AP5 decreased the apparent number of PCP/sigma-receptors in dose-dependent fashion without affecting their affinity for [2-thienyl-3H]cyclohexylpiperidine (TCP). These data, taken together with electrophysiological evidence that PCP non-competitively antagonizes NMDA receptor-mediated transmission, are consistent with the hypothesis that the PCP/sigma-receptor may be situated in or near a channel regulated by an NMDA receptor complex.

Characterization and autoradiographic visualization of (+)-[3H]SKF10,047 binding in rat and mouse brain: further evidence for phencyclidine/"sigma opiate" receptor commonality

The binding specificity of (+)-[3H]N-allylnormetazocine, the dextrorotatory isomer of the prototypical sigma opiate SKF10,047, was determined in rat and mouse brain and the neuroanatomical distribution of its binding sites elucidated by quantitative autoradiography in sections of rat brain. Computer-assisted Scatchard analysis revealed an apparent two-site fit of the binding data in both species and in all rat brain regions examined. In whole rat brain, the Kd values were 3.6 and 153 nM and the maximum binding values were 40 fmol and 1.6 pmol/mg of protein for the apparent high- and low-affinity binding sites, respectively. (+)-SKF10,047, haloperidol and pentazocine were among the most potent inhibitors of 7 nM (+)-[3H]SKF10,047 binding to the higher affinity sites; rank orders of ligand potencies at these sites differ sharply from those that have been reported for the [3H]phencyclidine (PCP) site, or for eliciting PCP-like or SKF10,047-like behaviors. By contrast, rank orders of potency of sigma opiods, PCP derivatives and dioxolanes for displacement of 100 nM (+)-[3H]SKF10,047 from the more numerous lower affinity sites in the presence of 100 nM haloperidol agreed closely with their potencies in the [3H]PCP binding assay as well as their potencies in exerting PCP- or SKF10,047-like behavioral effects. In order to compare directly the anatomical localizations of PCP and (+)-SKF10,047 binding sites, quantitative light microscopy autoradiography utilizing tritium-labeled PCP and (+)-SKF10,047 was carried out in rat brain sections. (+)-[3H]SKF10,047 binding was observed to follow the regional pattern of [3H]PCP binding but also to bind in other regions not associated with PCP receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitative localization of [3H]TCP binding in rat brain by light microscopy autoradiography

The anatomical localization of phencyclidine (PCP)/sigma-opiate receptors in rat brain was determined by quantitative light microscopy autoradiography using the new ligand N-(1-[2-thienyl]cyclohexyl) [3H]piperidine ([3H]TCP). TCP is a potent analog of PCP which possesses a higher affinity for PCP/sigma-opiate receptor than does PCP itself. The highest level of [3H]TCP binding was detected in the hippocampus. Intermediate levels were found in frontal cortex, striatum, amygdala and cerebellum. Specific [3H]TCP binding was undetectable in anterior commissure and corpus callosum. The distribution pattern of [3H]TCP binding sites is similar to the pattern obtained with [3H]PCP but more sharply defined. On the basis of its greater potency and specificity, [3H]TCP may prove superior to [3H]PCP as a molecular probe for the study of brain sigma opiate/phencyclidine receptors.