Treatment of a life-threatening dapsone intoxication.

The case report describes a case of a severe dapsone (more than 200 tablets dapsone 100 mg) and mild methotrexate intoxication (10 tablets methotrexate 10 mg) as an attempt to commit suicide, resulting in severe cyanosis with elevation in methemoglobin concentration, treated with methylene blue, ascorbic acid, folinic acid, multidose activated charcoal and hemodialysis. Measurements of blood gases, dapsone and methotrexate levels were performed. Furthermore a hepatitis, pulmonary artery thrombus and a strange taste sensation were diagnosed, probably related to dapsone. The patient recovered and was discharged from hospital after five days. Acute intoxication from excessive dapsone intake is uncommon and clear treatment guidelines are lacking. We here report the treatment modalities as a result of a dapsone intoxication, including the effects on the overall condition of the patient.

Insight in Information Provision Prior to Obtaining Surgical Informed Consent-by Audiotaping Outpatient Consultations.

BACKGROUND: Literature suggests that patient-informing process prior to obtaining surgical informed consent (SIC) does not function well. This study aimed to provide insight into the current practice of SIC in the Netherlands. METHODS: This is a prospective, observational, and multicenter study, conducted in one academic and two non-academic teaching hospitals in the Netherlands. Audio recordings were made during outpatient consultations with patients presenting with Dupuytren Disease. The recorded informing process was scored according to a checklist. Written documentation of the SIC process in the patient's chart was compared to these scored checklists. Time spent on SIC during the consultations was also recorded. RESULTS: A total of 41 outpatient consultations were included in the study. Consultations were conducted by 25 plastic surgeons and their residents. Average time spent on SIC was 55.6% of the total consultation time. Considerable variation was observed concerning the amount and type of information given and discussed. In 59% of the consultations, discrepancies were observed between written documentation of consultations and audio recordings. Information on treatment risks, the postoperative period, and the operating surgeon was addressed the least. CONCLUSION: Despite a relatively large part of the consultation time being spent on SIC, patients received scarce information concerning treatment risks, postoperative period, and who their operating surgeon would be. Discrepancies were observed between the written documentation of SIC and information recorded on the audio recordings. This occurred predominantly in one hospital that used a pre-made list of 'discussed information' in its digital patient chart.

A decade of litigation regarding surgical informed consent in the Netherlands.

OBJECTIVE: An inadequate surgical informed consent process (SIC) may result in a medical malpractice claim or medical disciplinary board (MDB) complaint. Aim of this study was to analyse characteristics of a decade of malpractice claims and MDB decisions regarding SIC in the Netherlands. METHODS: A retrospective analysis of malpractice claims and MDB decisions concerning SIC disputes in four major surgical specialties was conducted based on company data from the largest medical malpractice insurance company and two public available online MDB databases. RESULTS: A total of 11376 malpractice claims and 661 MDB complaints were filed between 2004-2013 and 676(6%) of these claims and 69(10%) of these complaints involved an alleged deficient SIC process. A random sample of 245(37%) claims and all MDB decisions were analysed. Reasons for filing a claim or complaint were insufficient counselling or recording of SIC elements. In 20% of lawsuits and 25% of claims the case resulted in favour of the complainant. CONCLUSION: A substantial portion of malpractice claims and MDB decisions is related to a deficient SIC process. PRACTICE IMPLICATIONS: Focusing on crucial SIC elements for patients may improve satisfaction and expectations and result in a lower risk for malpractice claims and MDB complaints.

Stability of filgrastim and epoetin alfa in a system designed for enteral administration in neonates.

OBJECTIVE: To determine the stability of recombinant granulocyte colony-stimulating factor (rG-CSF, filgrastim) and recombinant erythropoietin (rEpo, epoetin alfa) in a solution designed for enteral administration in the neonatal intensive care unit. DESIGN: Filgrastim and epoetin alfa were added to a solution with NaCl 0.9%, sodium acetate, potassium chloride, and human albumin in concentrations designed to mimic human amniotic fluid. Additionally, the solution was dripped through polyvinyl chloride feeding tubes to simulate feedings, and aliquots were collected before, during, and after priming of the tube. Other aliquots were either frozen immediately, stored at room temperature, or refrigerated for 0, 6, 12, 18, and 24 hours. MAIN OUTCOME MEASURES: Filgrastim and epoetin alfa concentrations in the various aliquots were compared with the concentrations in the original solution. RESULTS: Filgrastim and epoetin alfa concentrations were stable for at least 24 hours when refrigerated and for at least three weeks when frozen. At room temperature, filgrastim was stable for 18 hours and epoetin alfa for 24 hours. Filgrastim concentrations did not vary significantly before, during, or after priming of the feeding tube, whereas epoetin alfa concentrations decreased significantly unless the feeding tube was primed with 10 mL of solution. CONCLUSIONS: Filgrastim and epoetin alfa were stable in our amniotic fluid-like solution. In this respect, our solution is suitable for enteral administration to patients in the neonatal intensive care unit.

Myeloid dendritic cells induce Th2 responses to inhaled antigen, leading to eosinophilic airway inflammation.

The aim of this study was to investigate whether dendritic cells (DCs) can induce sensitization to aeroallergen in a mouse model of allergic asthma. Ovalbumin-pulsed (OVA-pulsed) or unpulsed myeloid DCs that were injected into the airways of naive mice migrated into the mediastinal lymph nodes. When challenged 2 weeks later with an aerosol of OVA, activated CD4 and CD8 lymphocytes, eosinophils, and neutrophils were recruited to the lungs of actively immunized mice. These CD4(+) lymphocytes produced predominantly IL-4 and IL-5 but also IFN-gamma, whereas CD8(+) lymphocytes produced predominantly IFN-gamma. Histological analysis revealed perivascular and peribronchial eosinophilic infiltrates and goblet cell hyperplasia. Studies in IL-4(-/-) and CD28(-/-) mice revealed that production of IL-4 by host cells and provision of costimulation to T cells by DCs were critical for inducing the response. Lung CD4(+) T cells strongly expressed the Th2 marker T1/ST2, and signaling through this molecule via a ligand expressed on DCs was essential for the establishment of airway eosinophilia. These data demonstrate that DCs in the airways induce sensitization to inhaled antigen and that molecules expressed on the surface of these cells are critical for the development of Th2-dependent airway eosinophilia.

Selective initial in vivo homing pattern of 5T2 multiple myeloma cells in the C57BL/KalwRij mouse.

One of the main characteristics of multiple myeloma cells is their predominant localization in the bone marrow. It is, however, unclear whether this is due to a selective initial entry, or whether this entry is more random and other processes like survival and/or growth stimulation, only present in the medullar microenvironment, are unique. To investigate this, in vivo homing kinetics of murine 5T2MM cells shortly after injection were assessed in bone marrow, liver, spleen, lungs, heart, intestines, kidney and testis by tracing of radiolabelled cells, by immunostaining of isolated cells and by polymerase chain reaction analysis. We demonstrated the presence of 5T2MM cells in bone marrow, spleen and liver with all other organs being negative. Adhesion assays of 5T2MM cells to different types of endothelial cells demonstrated a selective adhesion of 5T2MM cells to bone marrow and liver and not to lung endothelial cells. We here demonstrate that the specific in vivo localization of the 5T2MM cells is a result of the combination of a selective entry/adhesion of the 5T2MM cells in the bone marrow, spleen and liver, and a selective survival and growth of these tumour cells in the bone marrow and spleen but not in the liver.

Granulocyte colony-stimulating factor serum and urine concentrations in neutropenic neonates before and after intravenous administration of recombinant granulocyte colony-stimulating factor.

BACKGROUND: Recombinant granulocyte colony-stimulating factor (rG-CSF) has been suggested as a treatment for certain varieties of neonatal neutropenia, but little is known about the pharmacologic disposition of rG-CSF in that population. METHODS: Ten neutropenic neonates were treated with rG-CSF, 10 micrograms/kg intravenously once daily for 3 to 5 days. Serum and urine samples were obtained before rG-CSF dosing and at intervals thereafter for G-CSF quantification by enzyme-linked immunosorbent assay. RESULTS: Five of the neutropenic neonates (termed group 1) were not infected but likely had hyporegenerative neutropenia (4 were born after pregnancy-induced hypertension/intrauterine growth restriction, and 1 had Rh hemolytic disease). Five other infants (group 2) had neutropenia accompanying bacterial sepsis and shock. Before receiving the first dose of rG-CSF, endogenous G-CSF serum and urine concentrations were relatively low in group 1, averaging 130 pg/mL (range: 48-209) in serum and 53 pg/mL (range: 15-141) in urine. Serum concentrations immediately before the final dose were much higher (range: 81-24 835 pg/mL), whereas urine concentrations were unchanged (range: <7 pg/mL-126 pg/mL). In group 2 patients, before receiving the first-dose of rG-CSF, endogenous concentrations were very high, averaging 59 575 pg/mL (range: 20 028-98 280) in serum and 3189 pg/mL (range: 23-4770) in urine. Predose serum concentrations before the final dose (range: 427-14 460 pg/mL) were lower than before the first dose. The area under the concentration curve after the first dose of rG-CSF administration in group 1 was significantly lower than after the first dose in group 2, but no difference in area under the concentration curve was observed between groups 1 and 2 after the last dose of rG-CSF. SPECULATION: The principal means of clearing G-CSF from the serum is by saturable binding to specific G-CSF receptors (G-CSF-Rs). Therefore, the very high G-CSF serum and urine concentrations of group 2 patients before the first rG-CSF dose implies that their G-CSF-Rs were saturated before the dose was given. We speculate that if G-CSF-Rs are saturated with endogenous G-CSF, treatment with rG-CSF will add little or nothing to the granulocytopoietic effort. On this basis, we judge that neonates with septic shock and neutropenia are unlikely to derive benefit from rG-CSF administration.

Endogenously produced substance P contributes to lymphocyte proliferation induced by dendritic cells and direct TCR ligation.

Substance P (SP) is an immunoregulatory tachykinin which augments antigen- and mitogen-induced lymphocyte proliferation via signaling through the neurokinin-1 receptor (NK1-R). Non-neuronal cells of the immune system such as monocytes, T lymphocytes and eosinophils can be a source of SP. We have investigated if antigen-presenting dendritic cells (DC) produce SP. DC were grown from bone marrow precursors using a cocktail of GM-CSF, IL-4 and Flt-3 ligand. Reverse transcriptase-PCR amplification using primers for the mouse preprotachykinin-A gene and direct DNA sequencing of amplified products from purified DC demonstrated the presence of the gamma-transcript of the gene, coding for SP and neurokinin A. At the protein level, mouse DC expressed SP as determined by an enzyme immunoassay and confirmed by immunostaining. The functional role of endogenous SP release was determined. During the interaction with syngeneic or allogeneic DC, the addition of a specific NK1-R antagonist partly reduced proliferation in responding T lymphocytes. This was confirmed by using responders derived from NK1-R-deficient mice. In the absence of DC, proliferation of T cells induced by direct TCR ligation and soluble CD28 was partly dependent on signaling through NK1-R, revealing an autocrine effect of SP production by T cells. In conclusion, these results demonstrate that endogenously produced SP contributes to T cell proliferation induced by DC or TCR / CD28 stimulation.

CD40 ligation prevents Trypanosoma cruzi infection through interleukin-12 upregulation.

Because of the critical role of the CD40-CD40 ligand (CD40L) pathway in the induction and effector phases of immune responses, we investigated the effects of CD40 ligation on the control of Trypanosoma cruzi infection. First, we observed that supernatants of murine spleen cells stimulated by CD40L-transfected 3T3 fibroblasts (3T3-CD40L transfectants) prevent the infection of mouse peritoneal macrophages (MPM) by T. cruzi. This phenomenon depends on de novo production of nitric oxide (NO) as it is prevented by the addition of N-nitro-L-arginine methyl ester, a NO synthase inhibitor. NO production requires interleukin (IL)-12-mediated gamma interferon (IFN-gamma) and tumor necrosis factor alpha (TNF-alpha) synthesis as demonstrated by inhibition experiments using neutralizing anti-IL-12, anti-IFN-gamma, and anti-TNF-alpha monoclonal antibodies (MAb). We found that an activating anti-CD40 MAb also directly stimulates IFN-gamma-activated MPM to produce NO and thereby to control T. cruzi infection. To determine the in vivo relevance of these in vitro findings, mice were injected with 3T3-CD40L transfectants or 3T3 control fibroblasts at the time of T. cruzi inoculation. We observed that in vivo CD40 ligation dramatically reduced both parasitemia and the mortality rate of T. cruzi-infected mice. A reduced parasitemia was still observed when the injection of 3T3-CD40L transfectants was delayed 8 days postinfection. It was abolished by injection of anti-IL-12 MAb. Taken together, these data establish that CD40 ligation facilitates the control of T. cruzi infection through a cascade involving IL-12, IFN-gamma, and NO.

Retrovirally transduced bone marrow-derived dendritic cells require CD4+ T cell help to elicit protective and therapeutic antitumor immunity.

It has been extensively documented that murine dendritic cells loaded with tumor-associated Ag (TAA)-derived peptides or protein can prime Ag-specific CD8+ cytotoxic T cells in vivo and can elicit Ag-specific immunity. Optimal presentation of TAA might be achieved by retroviral transduction of DCs allowing long term and stable expression of the TAA-peptides as well as the presentation of multiple epitopes in the context of MHC class I and/or class II molecules. Here we show that retroviral transduction of bone marrow-derived dendritic cells (DCs) with chicken OVA cDNA or the reporter gene green fluorescent protein retained their potent stimulatory capacity and that the transduced DCs could process and present the endogenously expressed OVA protein. The DCs transduced with cDNA encoding native OVA protein presented OVA-derived peptides in the context of MHC class I as well as MHC class II and induced a strong Ag-specific CTL response. DCs expressing a cytosolic form of OVA presented OVA peptides only in the context of MHC class I and failed to induce an OVA-specific CTL response in vivo when they had been cultured in the absence of exogenous protein. Immunization with retrovirally transduced DCs resulted in an Ag-specific immunity and rejection of a tumor cell challenge and a significant survival advantage in tumor-bearing mice. These results obtained in this rapidly lethal tumor model suggest that DCs transduced with TAA may be useful for tumor immunotherapy and underscore the importance of the simultaneous delivery of T cell help in the development of Ag-specific cytotoxic T-cells.

In vivo retargeting of T cell effector function by recombinant bispecific single chain Fv (anti-CD3 x anti-idiotype) induces long-term survival in the murine BCL1 lymphoma model.

As demonstrated in several preclinical models, bispecific Abs are attractive immunotherapeutic agents for tumor treatment. We have previously reported that a bacterially produced anti-CD3 x antitumor bispecific single chain variable fragment of Ab fragment (BsscFv), which is capable of retargeting CTLs toward BCL1 tumor cells, exhibits antitumor activity in vitro. To further facilitate BsscFv production, the coding sequence was subcloned in a eukaryotic expression vector and introduced into Chinese hamster ovary cells for large-scale production. In this report, we have determined the serum stability and the clearance rate from the circulation of BsscFv. Most important, we prove here the therapeutic value of BsscFv in the treatment of BCL1 lymphoma, a murine model for human non-Hodgkin's lymphoma. Tumor-bearing mice that were treated with rscFv in combination with staphylococcal enterotoxin B superantigen, human rIL-2, or murine rIL-12 showed long-term survival, whereas untreated mice all died. This is the first report of the successful in vivo use of BsscFv as an immunotherapeutic agent. Furthermore, long-term survival was the result of complete tumor removal and was not due to the induction of dormancy.

IL-12 prevents neonatal induction of transplantation tolerance in mice.

We investigated the effect of IL-12 on the induction of transplantation tolerance by neonatal injection of allogenic cells. We first observed that injection of newborn BALB/c mice with IL-12 and (A/J x BALB/c)F1 spleen cells prevented the Th2 alloimmune response induced by neonatal inoculation of F1 cells alone and allowed the differentiation of T cells secreting high amounts of IL-2 and IFN-gamma in mixed lymphocyte cultures with donor-type stimulators. Furthermore, IL-12 administration resulted in the emergence of anti-donor cytotoxic T lymphocyte responses although at lower levels than in control uninjected mice. In parallel, we found that mice injected at birth with IL-12 and F1 cells did not develop chimerism and were able to reject a donor-type skin graft as efficiently as control mice. We conclude that IL-12 inhibits the Th2 polarization of the newborn response to alloantigens and prevents thereby the establishment of transplantation tolerance.

Enteral glutamine supplementation for very low birth weight infants decreases morbidity.

Glutamine, described as a "conditionally essential" amino acid for critically ill patients, has not been routinely added to parenteral amino acid formulations for critically ill neonates and is provided in only small quantities by the enteral route when enteral intake is low. We conducted a blinded, randomized study of enteral glutamine supplementation in 68 very low birth weight neonates randomly assigned to receive glutamine-supplemented premature formula versus premature formula alone between days 3 and 30 of life. Primary end points consisted of hospital-acquired sepsis, tolerance to subsequent enteral feedings (days with no oral intake), and duration of hospital stay. Hospital acquired sepsis was 30% (control group) and 11% (glutamine group). Logistic regression with birth weight as a covariate showed that: (1) feeding group was significant (p = 0.048) in determining the probability of developing proven sepsis over the course of hospitalization and (2) the estimated odds of developing sepsis were 3.8 times higher for infants in the control group than for those treated with glutamine. Glutamine-supplemented infants had better tolerance to enteral feedings as measured by percent of days on which feedings needed to be withheld (mean percentage of 8.8 vs 23.8, p = 0.007). Analysis of T cells demonstrated a blunting of the rise in HLA-DR+ and CD16 subsets in glutamine-supplemented infants. There were no differences in growth; in serum ammonia, urea, liver transaminase, or prealbumin concentrations; or in mean hospital stay. This study provides evidence for decreased morbidity in very-low-birth-weight neonates who receive enteral glutamine supplementation.

Phe-Met-Arg-Phe-amide activates a novel voltage-dependent K+ current through a lipoxygenase pathway in molluscan neurones.

The neuropeptide Phe-Met-Arg-Phe-amide (FMRFa) dose dependently (ED50 = 23 nM) activated a K+ current in the peptidergic caudodorsal neurones that regulate egg laying in the mollusc Lymnaea stagnalis. Under standard conditions ([K+]o = 1.7 mM), only outward current responses occurred. In high K+ salines ([K+]o = 20 or 57 mM), current reversal occurred close to the theoretical reversal potential for K+. In both salines, no responses were measured below -120 mV. Between -120 mV and the K+ reversal potential, currents were inward with maximal amplitudes at approximately -60 mV. Thus, U-shaped current-voltage relations were obtained, implying that the response is voltage dependent. The conductance depended both on membrane potential and extracellular K+ concentration. The voltage sensitivity was characterized by an e-fold change in conductance per approximately 14 mV at all [K+]o. Since this result was also obtained in nearly symmetrical K+ conditions, it is concluded that channel gating is voltage dependent. In addition, outward rectification occurs in asymmetric K+ concentrations. Onset kinetics of the response were slow (rise time approximately 650 ms at -40 mV). However, when FMRFa was applied while holding the cell at -120 mV, to prevent activation of the current but allow activation of the signal transduction pathway, a subsequent step to -40 mV revealed a much more rapid current onset. Thus, onset kinetics are largely determined by steps preceding channel activation. With FMRFa applied at -120 mV, the time constant of activation during the subsequent test pulse decreased from approximately 36 ms at -60 mV to approximately 13 ms at -30 mV, confirming that channel opening is voltage dependent. The current inactivated voltage dependently. The rate and degree of inactivation progressively increased from -120 to -50 mV. The current is blocked by internal tetraethylammonium and by bath- applied 4-aminopyridine, tetraethylammonium, Ba2+, and, partially, Cd2+ and Cs+. The response to FMRFa was affected by intracellular GTPgammaS. The response was inhibited by blockers of phospholipase A2 and lipoxygenases, but not by a cyclo-oxygenase blocker. Bath-applied arachidonic acid induced a slow outward current and occluded the response to FMRFa. These results suggest that the FMRFa receptor couples via a G-protein to the lipoxygenase pathway of arachidonic acid metabolism. The biophysical and pharmacological properties of this transmitter operated, but voltage-dependent K+ current distinguish it from other receptor-driven K+ currents such as the S-current- and G-protein-dependent inward rectifiers.

Bispecific antibody treatment of murine B cell lymphoma.

This report summarizes our experimental data concerning the use of bispecific antibodies (bsAb) for the treatment of the murine BCL1 B cell lymphoma model. Initially we used a hybrid-hybridoma-derived bsAb with specificity for the TcR/CD3 complex on T cells and the idiotype of the membrane-bound IgM on the tumor cells. The bsAb used as a single agent could cure animals with a low tumor load (resembling minimal residual disease). However, in experiments aimed at increasing the therapeutic effect in animals with a higher tumor burden, we could demonstrate the importance of additional T-cell-costimulatory signals and the careful timing of the bsAb administration. Recently we have generated a bispecific single-chain Fv (bsscFv) fusion protein with the same dual specificity as the hybrid-hybridoma-derived bsAb. Immunotherapy with this smaller molecule also resulted in tumor elimination in BCL1-bearing mice. A second bsscFv (alpha-CD19 x alpha-CD3) with a broader applicability is now being characterized and tested in vivo.

Pharmacokinetics and effectiveness of recombinant erythropoietin administered to preterm infants by continuous infusion in total parenteral nutrition solution.

OBJECTIVES: To compare the pharmacokinetics and effectiveness of continuously administered recombinant erythropoietin (Epo) in total parenteral nutrition (TPN) solution with daily subcutaneously administered Epo. METHODS: Forty preterm infants in the first 72 hours of life were randomly assigned to receive Epo (200 units/kg per day for 10 consecutive days), either subcutaneously (20 infants, 1051 +/- 40 gm, 28.3 +/- 0.4 weeks of gestation; mean +/- SEM), or added daily to their TPN fluids (20 infants, 1028 +/- 36 gm, 27.9 +/- 0.4 weeks of gestation). Both groups received iron supplementation (1 mg/kg per day iron dextran in the TPN solution). Absolute reticulocyte counts and complete blood cell counts with differentials were measured, and transfusions and phlebotomy losses were recorded. Pharmacokinetics were determined in the first 16 infants. RESULTS: In the infants who received Epo subcutaneously, the elimination half-life was 17.6 +/- 4.4 hours on day 3 and 11.2 +/- 1.5 hours on day 10; the volume of distribution was 802 +/- 190 ml/kg on day 3 and 1330 +/- 243 m/kg on day 10. Serum Epo concentrations were higher on day 3 than on day 10 for both groups (subcutaneous: 400 +/- 64 mU/ml vs 177 +/- 29 mU/m, p <0.05; TPN: 395 +/- 64 vs 194 +/- 41 mU/ml, p <0.05). Clearance did not differ between the two groups with regard to route of administration and increased significantly from days 3 to 10 in both groups. Reticulocyte counts were similar in both groups. There were no differences between groups in the number of transfusions given, and the overall decline in hematocrit was similar. No adverse effects of Epo were noted in either group. CONCLUSIONS: Adding Epo to the TPN solution in this population results in similar Epo concentrations, clearance, and effectiveness as subcutaneous dosing.

Interference of polychlorinated biphenyls in hepatic and brain thyroid hormone metabolism in fetal and neonatal rats.

The effects of prenatal oral administration of 0.2, 0.6, and 1.8 mg/kg body wt of 3,3',4,4'5,5'-hexachlorobiphenyl (HCB) on Day 1 of gestation and a combination of 1 mg/kg 3,3',4,4'-tetrachlorobiphenyl (TCB) from Day 2 to Day 18 with 0.6 mg HCB/kg body wt on Day 1 of gestation on thyroid hormone status and peripheral thyroid metabolism were studied in pregnant Wistar rats and their fetuses and offspring. Plasma total thyroxine and free thyroxine levels were reduced by HCB in a dose-dependent fashion in pregnant rats (Days 12 and 20 of gestation) and neonates (Day 21 postpartum), while only a combined dose of HCB and TCB was effective in decreasing fetal thyroid hormone levels by 65% on Day 20 of gestation. The activity of type II thyroxine 5'-deiodinase (5'D-II), the enzyme responsible for the deiodination of thyroxine (T4) to biologically active triiodothyronine in the brain, was examined in whole brain homogenates in fetuses and neonates. Decreases in plasma thyroid hormones were accompanied by significant increases, up to 100%, in 5'D-II activity in brain homogenates from fetuses (Day 20 of gestation) and neonates (Days 7 and 21 postpartum). The glucuronidation of 125I-T4 by hepatic microsomes was increased by at least 100% relative to control levels by all treatments in fetuses (Day 20 of gestation) and increased at least 40% in neonates (Days 7 and 21 postpartum) by a dose of 0.6 and 1.8 mg HCB/kg and the combined dose. These data indicate that prenatal HCB and/or TCB administration result in increased peripheral T4 metabolism. The increase in 5'D-II activity suggests that local hypothyroidism occurs in the brains of fetal and neonatal rats exposed to HCB and/or TCB. Since these effects occur during a period in which thyroid hormones play an important role in brain maturation, they may help explain the mechanism of developmental neurotoxicity induced by polychlorinated biphenyls.

Hippocampal neuronal responsiveness to NMDA agonists and antagonists in the adult rat neonatally treated with MK-801.

Long-lasting effects of neonatal interference with N-methyl-D-aspartate (NMDA) receptors were investigated by measuring responses to micro-iontophoretically applied NMDA agonists/antagonist in hippocampal neurons of the adult rat. Rat pups were chronically treated with MK-801 from postnatal day 8 through 19 and tested at postnatal day 70-100. CA1 cell responses to glutamate were not affected by the neonatal treatment. However, a stronger suppression of the NMDA evoked response by the NMDA site antagonist amino-5-phosphonovalerate (APV) was measured, suggesting a long-lasting configurational change of the NMDA receptor. The NMDA evoked responses were equally strong suppressed by MK-801 in both groups, suggesting that channel sites were not affected by this treatment.