Behavioral and neuropsychological foundations of olfactory fear conditioning

Pavlovian fear conditioning procedures have been a fruitful means of exploring the neural substrates of associative learning. There is now substantial evidence suggesting that many aspects of conditioned fear depend critically upon the integrity of the amygdala and the perirhinal cortex. Recent studies in our laboratory examining the contributions of these areas to olfactory and contextual fear conditioning are reviewed; collectively the results of these studies suggest that the amygdala participates critically in the acquisition and expression of fear conditioned to both an olfactory conditioned stimulus (CS) and to the training context, while the perirhinal cortex contributes to olfactory, but not contextual, fear conditioning. Moreover, it appears that perirhinal cortex may play a prominent role in recognition of the CS following conditioning. These results are discussed in light of the extent to which they replicate and extend previous research examining the contributions of these areas to fear conditioned to auditory and visual CSs.

Comparison of immunogenicity and safety of a virosome influenza vaccine with those of a subunit influenza vaccine in pediatric patients with cystic fibrosis

The objective of this study was to compare the immunogenicity and safety of a single-dose regimen and a two-dose regimen of a trivalent virosome influenza vaccine (Inflexal Berna V) with those of a trivalent subunit influenza vaccine (Influvac) in children and adolescents with cystic fibrosis (CF). In an open, randomized, multicenter study with parallel groups, 11 young children with CF (1 to 6 years old) and 53 older children and adolescents with CF (>6 years old) were randomly assigned to one of the following immunization regimens: virosome vaccine at 0.5 ml on study day 0 or 0.25 ml on days 0 and 28 or a standard regimen of subunit vaccine, i. e., 0.5 ml on day 0 for older children and 0.25 ml on days 0 and 28 for younger children. Safety assessments, i.e., recording of systemic and local adverse events (AEs) and vital signs, were made for a 5-day observation period after each immunization. Hemagglutination inhibition (HI) titers were determined at baseline and 4 weeks after the single-dose and the two-dose immunizations, respectively. Immunogenicity was assessed according to the criteria of the European Agency for the Evaluation of Medicinal Products (EMEA). Both vaccines induced comparable HI antibody titers. Seroconversion (> or =4-fold rise in HI antibody titers, reaching a titer of > or =1:40) was achieved in 41 to 100% of the participants. Seroprotection (HI titer, > or =1:40) and a >2.5-fold increase in geometric mean titers were achieved in 100% of the participants. Thus, all three EMEA requirements for influenza vaccine efficacy were met by all treatment groups and for both vaccines. The virosome vaccine, when administered as a single dose, seemed to induce superior immunogenicity compared with the standard pediatric two-dose regimen. Totals of 42 and 57% of vaccinees receiving virosome and subunit vaccines, respectively, reported at least one local AE (predominantly pain). Totals of 84 and 71% of subjects receiving virosome and subunit vaccines, respectively, complained in response to questions of at least one systemic AE (mainly cough, fatigue, coryza, or headache). The majority of events were mild or moderate and lasted 1 or 2 days only. No obvious relationship was found between AE reporting rate and vaccine formulation, age group, or dose regimen. The relatively high AE reporting rate seemed to be partly related to the symptomatology of the underlying CF disease. In summary, the virosome and subunit vaccines induced in both age groups and against all three influenza strains an efficient immune response and were well tolerated by the children and adolescents with CF.

Foreign-body reaction to silastic burr-hole covers with seroma formation: case report and review of the literature

Because silastic material is one of the most commonly used biomaterials in modern medicine, the biocompatibility of these implants is still a source of long standing controversy. Though several studies have established silastic material as biologically inert, numerous authors have repeatedly described characteristic pathological tissue responses to silicone and its elastomeres. We report a case of foreign-body reaction to silastic burr-hole cover with successive formation of a seroma following resection of an olfactory groove meningioma. Within 30 days postoperatively, the patient developed a marked bulge in the glabbelar region. Histopathological examination revealed a seroma-like lesion obviously caused by a chronic inflammatory allergic reaction to the silastic burr-hole cover. Although the silicone-induced tissue damage clinically shows a wide variability and a conclusive model of pathogenesis is presently not available, the histopathological findings in some patients, in the form of granulomatous lesions and inflammatory cell response, might partly be due to an immunological reaction. Such a reaction has been previously described both clinically and experimentally, as detected in our patient. In addition, a review of the literature is given.

Safety and immunogenicity of intranasally administered inactivated trivalent virosome-formulated influenza vaccine containing Escherichia coli heat-labile toxin as a mucosal adjuvant

A trivalent influenza virosome vaccine containing hemagglutinin and Escherichia coli heat-labile toxin (HLT) was administered intranasally to young adults and elderly subjects. Symptoms that followed immunization were mild and transient. A significant increase in serum hemagglutination inhibition (HI) antibody was noted for the 3 vaccine strains. There was no significant difference in postimmunization geometric mean titers or seroconversion rates between age groups. The percentage of subjects attaining protective HI titers (>/=40%) was comparable in both groups for the A/Bayern (P=.5) and B/Beijing (P=.3) strains but was higher among young adults (92.2%) versus elderly subjects (76.5%; P=.057) for the A/Wuhan strain. The proportion of subjects with nonprotective baseline titers who attained protective levels after immunization was similar in both age groups for the A/Bayern and B/Beijing components. For the A/Wuhan component, significantly (P=.017) more young adults achieved protective titers versus elderly subjects (85. 7% and 53.8%, respectively). Vaccination evoked a significant (P<. 005) increase in anti-HLT antibody titers.

Regeneration of olfactory receptor neurons following chemical lesion: time course and enhancement with growth factor administration

Although it has been known for over 50 years that olfactory receptor neuron (ORN) neurogenesis and subsequent reinnervation of the olfactory bulb (OB) occurs following ORN injury, the precise intrinsic and extrinsic factors that regulate this dynamic process have not yet been fully identified. In the first of two experiments, we characterized the time course of anatomical recovery following zinc sulfate (ZnSO(4)) lesion of ORNs in adult male Sprague-Dawley rats. ZnSO(4) produced a near complete deafferentation of OB within 3 days following intranasal administration. A time-dependent increase in ORN reinnervation of OB was observed following 10, 20, and 30 day recovery intervals. Given the evidence that bFGF, EGF, and TGF-alpha have mitogenic effects on ORNs in vitro, a second experiment examined the extent to which these growth factors (GFs) might enhance ORN regeneration and subsequent reinnervation of OB in vivo. Rats received intranasal infusions of ZnSO(4) on day 0, followed by subcutaneous injections of either bFGF (5, 10, or 50 microgram/kg), EGF (5, 10, or 50 microgram/kg), or TGF-alpha (5 or 10 microgram/kg) on days 3-6. Horseradish peroxidase (HRP) histochemistry of OB following a 10-day recovery period revealed a dose-related enhancement in reinnervation of OB for each of the three growth factors examined, with the greatest enhancement produced by TGF-alpha. These data suggest that GFs may regulate ORN mitogenesis in vivo in a way similar to that which has been characterized in vitro.

[Noninvasive protocol for surgical treatment of focal epilepsies]

We present a non-invasive epilepsy surgery protocol, which includes EEG-video-monitoring, magnetic resonance imaging (MRI), interictal positron emission tomography (PET) and ictal single photon emission computerized tomography (SPECT). According to this non-invasive protocol 50 of 173 patients with medically intractable focal epilepsy underwent resective surgery. The localization of the epileptogenic zone was based on the congruence of the localizing results of EEG-video-monitoring, MRI, interictal PET and ictal SPECT. 46 (92%) of the patients had temporal and 4 (8%) had extratemporal epilepsies. 78% (n = 39) of all patients operated according to our non-invasive protocol were postoperatively completely or almost seizure free. Extramesiotemporal resections could be carried out without invasive EEG-recording if the epileptogenic zone was not adjacent to the eloquent cortex. We conclude from our results that in a considerable number of patients with medically intractable particularly temporal focal epilepsies, resective epilepsy surgery can be based on non-invasive EEG-evaluations and the risk of invasive recordings can be avoided.

Adenovirus-mediated human topoisomerase IIalpha gene transfer increases the sensitivity of etoposide-resistant human breast cancer cells

Cellular resistance to chemotherapeutic agents is attributable to several mechanisms, including alteration of topoisomerase IIalpha (topo IIalpha) gene expression. Etoposide-resistant MDA-VP human breast cancer cells express lower amounts of enzymatically active and drug-sensitive topo IIalpha than do MDA parent cells, suggesting that the low level of topo IIalpha is the mechanism of resistance. To determine whether transfer of a normal topo IIalpha gene into MDA-VP cells can increase topo IIalpha gene expression, topo IIalpha protein production, and cell sensitivity to etoposide, a recombinant adenovirus, Ad-hTopoIIalpha, containing the human topo IIalpha gene, was constructed. The shuttle vector pAvCvSv-hTopIIalpha was constructed and co-transfected with the pBHG10 packaging vector into 293 cells. Infectious recombinant adenovirus plaques were isolated and purified. Presence of the topo IIalpha gene was confirmed by PCR and restriction enzyme digestion. After infection with Ad-hTopoIIalpha, topo IIalpha mRNA expression in MDA-VP cells increased 7.4-fold, topo IIalpha protein production increased 5.9-fold, and sensitivity to etoposide was enhanced 4.5-fold compared with control transfected cells. Infection of normal human embryonic lung cells and human fibroblast cells with Ad-hTopoIIalpha did not enhance the expression of topo IIalpha or sensitivity to etoposide. Viral uptake was comparable in the MDA-VP and normal cell lines. These data suggest that topo IIalpha gene transfer using an adenoviral vector can selectively increase etoposide sensitivity in drug-resistant tumor cells and may enhance the therapeutic index of etoposide.

Structure and function of residue 104 and water molecules in the xenobiotic substrate-binding site in human glutathione S-transferase P1-1

Two variants of human class pi glutathione (GSH) S-transferase 1-1 with either isoleucine or valine in position 104 (hGSTP1-1[I104] and hGSTP1-1[V104]) have distinct activity toward (+)-anti-7, 8-dihydroxy-9,10-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene [(+)-anti-BPDE]. To elucidate their structure-function relationship, we determined the crystal structures of the two variants in complex with GSBpd, the GSH conjugate of (+)-anti-BPDE, at 2.1 and 2.0 A resolution, respectively. The crystal structures reveal that residue 104 in the xenobiotic substrate-binding site (H-site) dictates the binding modes of the product molecule GSBpd with the following three consequences. First, the distance between the hydroxyl group of Y7 and the sulfur atom of GSBpd is 5.9 A in the hGSTP1-1[I104].GSBpd complex versus 3.2 A in the V104 variant. Second, one of the hydroxyl groups of GSBpd forms a direct hydrogen bond with R13 in hGSTP1-1[V104].GSBpd; in contrast, this hydrogen bond is not observed in the I104 complex. Third, in the hydrophilic portion of the H-site of the I104 complex, five H-site water molecules [Ji, X., et al. (1997) Biochemistry 36, 9690-9702] are observed, whereas in the V104 complex, two of the five have been displaced by the Bpd moiety of GSBpd. Although there is no direct hydrogen bond between Y108 (OH) and the hydroxyl groups of GSBpd, indirect hydrogen bonds mediated by water molecules are observed in both complexes, supporting the previously suggested role of the hydroxyl group of Y108 as an electrophilic participant in the addition of GSH to epoxides.

Transcallosal approach to the third ventricle: normative morphometric data based on magnetic resonance imaging scans, with special reference to the fornix and forniceal insertion

OBJECTIVE

The ability to visualize median-sagittal brain structures by magnetic resonance imaging (MRI) improves the planning for surgical removal of lesions located in and around the third ventricle. The transcallosal approach is the most appropriate path to the anterior part of the third ventricle. The present study was undertaken to obtain normative morphometric data, derived from sagittal MRI scans, which are necessary for operation planning that takes into account the surgical microanatomy and landmarks encountered during this approach.

METHODS

The morphometric evaluation was performed on 72 median-sagittal MRI scans. The surface landmarks for the corridor were the two points, P5 and P7, located 5 and 7 cm anterior to the central sulcus, respectively. With these two points on the cortical surface as references, a variety of measurements were made to provide quantitative information about distances between brain structures encountered during the surgical approach. In addition, various parameters were determined to characterize the different shapes of the fornix and the different types of forniceal insertion.

RESULTS

The following measurements (means) were obtained: 1) the distance between P5/P7 and the cingulate sulcus was 25.76 mm (range, 17.113-42.73 mm) with reference to P5, and 25.41 mm (range, 12.91-36.29 mm) with reference to P7; 2) the distance between the cingulate sulcus and the corpus callosum was 12.91 mm (range, 7.19-22.60 mm) with reference to P5, and 12.92 mm (range, 6.75-23.37 mm) with reference to P7; 3) the height of the corpus callosum was 6.22 mm (range, 3.07-9.00 mm) with reference to P5, and 6.92 mm (range, 3.50-13.57 mm) with reference to P7; 4) the distance between the anterior commissure and the foramen of Monro was 6.78 mm (range, 1.86-14.57 mm), independent of P5 and P7; 5) the distance between the lower margin of the corpus callosum and the upper insertion point of the fornix was 12.44 mm (range, 2.71-26.13 mm) with reference to P5, and 13.34 mm (range, 3.74-27.58 mm) with reference to P7; 6) the distance between the lower margin of the corpus callosum and the lower insertion point of the fornix was 18.08 mm (range, 9.47-29.71 mm) with reference to P5, and 18.58 mm (range, 10.48-30.40 mm) with reference to P7; and 7) the distance between the lower margin of the corpus callosum and the anterior commissure was 23.46 mm (range, 11.98-32.70 mm) with reference to P5, and 22.89 mm (range, 11.05-33.04 mm) with reference to P7. Four different insertion types between the fornix and the corpus callosum were noted and classified.

CONCLUSION

Morphometric data concerning the surrounding structures of the third ventricle have received very little attention in the literature. This morphometric study permitted definition of the surgical corridor to the third ventricle by preserving important anatomic structures such as the motor strip, genu of the corpus callosum, forniceal commissure (hippocampal commissure), anterior commissure, and forniceal columns. The detailed morphometric data obtained on median-sagittal MRI scans of the brain structures involved in the transcallosal interforniceal and/or transcallosal transforaminal approach allow for exact planning of the surgical approach.

Mucosal and systemic immune responses in humans after primary and booster immunizations with orally administered invasive and noninvasive live attenuated bacteria

The mucosal and systemic immune responses after primary and booster immunizations with two attenuated live oral vaccine strains derived from a noninvasive (Vibrio cholerae) and an invasive (Salmonella typhi) enteric pathogen were comparatively evaluated. Vaccination with S. typhi Ty21a elicited antibody-secreting cell (ASC) responses specific for S. typhi O9, 12 lipopolysaccharide (LPS), as well as significant increases in levels of immunoglobulin G (IgG) and IgA antibodies to the same antigen in serum. A strong systemic CD4(+) T-helper type 1 cell-mediated immune (CMI) response was also induced. In contrast to results with Ty21a, no evidence of a CMI response was obtained after primary immunization with V. cholerae CVD 103-HgR in spite of the good immunogenicity of the vaccine. Volunteers who received a single dose of CVD 103-HgR primarily developed an IgM ASC response against whole vaccine cells and purified V. cholerae Inaba LPS, and seroconversion of serum vibriocidal antibodies occurred in four of five subjects. Serum IgG anti-cholera toxin antibody titers were of lower magnitude. For both live vaccines, the volunteers still presented significant local immunity 14 months after primary immunization, as revealed by the elevated baseline antibody titers at the time of the booster immunization and the lower ASC, serum IgG, and vibriocidal antibody responses after the booster immunization. These results suggest that local immunity may interfere with colonization of the gut by both vaccine strains at least up to 14 months after basis immunization. Interestingly, despite a low secondary ASC response, Ty21a was able to boost both humoral (anti-LPS systemic IgG and IgA) and CMI responses. Evidence of a CMI response was also observed for one of three volunteers given a cholera vaccine booster dose. The direct comparison of results with two attenuated live oral vaccine strains in human volunteers clearly showed that the capacity of the vaccine strain to colonize specific body compartments conditions the pattern of vaccine-induced immune responses.

Differential protection against benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide-induced DNA damage in HepG2 cells stably transfected with allelic variants of pi class human glutathione S-transferase

The pi class glutathione S-transferase (GSTP1-1), which is polymorphic in human populations, is believed to play an important role in detoxification of the ultimate carcinogen of widespread environmental pollutant benzo[a]pyrene [(+)-anti-benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide [(+)-anti-BPDE]]. The allelic variants of human GSTP1-1 (hGSTP1-1) differ in their structures by the amino acids in positions 104 (isoleucine or valine) and/or 113 (valine or alanine). Here, we have determined the protective effect of overexpression of allelic variants of hGSTP1-1, through stable transfection in HepG2 cells, against (+)-anti-BPDE-induced DNA modification. Clonal transfectants of HepG2 cells corresponding to the three allelic variants of hGSTP1-1 [(I104,A113), (V104,A113), and (V104,V113), denoted hGSTP1(IA), hGSTP1(VA), and hGSTP1(VV), respectively] with similar levels of hGSTP1 protein were identified and characterized for their GST activity and (+)-anti-BPDE-induced DNA modification. The glutathione S-transferase activity toward (+)-anti-BPDE was significantly higher (approximately 3.0-3.6-fold) in cells transfected with hGSTP1(VA) [HepG2(VA)] and hGSTP1(VV) [HepG2(VV)] compared with hGSTP1(IA) transfectant [HepG2(IA)]. The formation of (+)-anti-BPDE-DNA adducts was significantly reduced in HepG2(VA) and HepG2(VV) cells compared with cells transfected with insert-free vector (HepG2-vect). Maximum protection against (+)-anti-BPDE-induced DNA damage was afforded by the hGSTP1(VV) isoform. The results of this study indicate that the allelic variants of hGSTP1-1 significantly differ in their ability to provide protection against (+)-anti-BPDE-induced DNA damage. Thus, hGSTP1-1 polymorphism may be an important factor in differential susceptibility of individuals to tumorigenesis induced by benzo[a]pyrene.

Response to measles revaccination among toddlers in Saudi Arabia by the use of two different trivalent measles-mumps-rubella vaccines

This trial confirmed the immunogenicity of a standard dose of measles vaccine Edmonston-Zagreb strain administered at the age of 6 months as evaluated serologically at 12 months of age in 94 healthy children in Saudi Arabia. The residual seropositivity rate for measles was 53.4 and 80.6% as measured by enzyme immunoassay (EIA) and plaque neutralization, respectively, and could be increased to virtually 100% seroprotection after immunization with 1 of 2 measles-mumps-rubella (MMR) vaccines (Triviraten Berna or MMR II MSD) at 12 months of age. In both groups, more than 90% of infants showed an immune response to the mumps and rubella vaccine strains at 14 months of age. There was a difference in the geometric mean titres of mumps antibodies in favour of MMR II (P < 0.001). The seroconversion rates for mumps antibodies differed between the 2 vaccines because of the different test systems and/or the different cut-off levels used. The study reconfirmed that for the assessment of Rubini mumps vaccine-induced antibodies the indirect immunofluorescence test is superior to the EIA. The systemic tolerability of both vaccines was excellent. Triviraten Berna is exclusively propagated on human diploid cell cultures and hence free of avian proteins.

Structure of catalase-A from Saccharomyces cerevisiae

The structure of the peroxisomal catalase A from the budding yeast Saccharomyces cerevisiae, with 515 residues per subunit, has been determined and refined to 2.4 A resolution. The crystallographic agreement factors R and Rfree are 15.4% and 19.8%, respectively. A tetramer with accurate 222-molecular symmetry is located in the asymmetric unit of the crystal. The conformation of the central core of catalase A, about 300 residues, remains similar to the structure of catalases from distantly related organisms. In contrast, catalase A lacks a carboxy-terminal domain equivalent to that found in catalase from Penicillium vitalae, the only other fungal catalase structure available. Structural peculiarities related with the heme and NADP(H) binding pockets can be correlated with biochemical characteristics of the catalase A enzyme. The network of molecular cavities and channels, filled with solvent molecules, supports the existence of one major substrate entry and at least two possible alternative pathways to the heme active site. The structure of the variant protein Val111Ala, also determined by X-ray crystallography at 2.8 A resolution, shows a few, well-localized, differences with respect to the wild-type enzyme. These differences, that include the widening of the entry channel in its narrowest point, provide an explanation for both the increased peroxidatic activity and the reduced catalatic activity of this mutant.

Contributions of anterior perirhinal cortex to olfactory and contextual fear conditioning

The present experiments examined the effects of excitotoxic lesions of anterior perirhinal cortex (PRH) on the expression of fear conditioned to an explicit olfactory CS and to the context in which CS-US pairing took place. Animals with anterior PRH lesions exhibited an attenuation of fear conditioned to the explicit CS, but no attenuation of fear conditioned to the training context. These data replicate previous findings in our laboratory examining the effects of aspirative lesions of anterior PRH, and are consistent with the notion that this cortical region comprises a critically important component of the neural system mediating the acquisition and/or expression of associations between olfactory cues and footshock.

Adverse events after oral vaccination against cholera with CVD103-HgR

The goal of the present study was to evaluate the tolerability and acceptability of an oral cholera vaccine (CVD103HgR) in individuals preparing for travel to countries endemic for cholera. 2545 Austrian travelers between 6 months and 81.5 years of age received a single dose of CVD103HgR and were asked to complete a questionnaire for documentation of adverse events during a 7 day period post immunization. Events were recorded regardless of whether they were caused by concomitant vaccinations or other factors and thus, a causative relationship was not necessarily present. Despite this drawback and the possibility of overreporting this study has proven a low frequency in side effects and the good tolerability of CVD103HgR. Occasional gastrointestinal side effects (15% diarrhea, 8.1% nausea, 1.1% vomiting) were seen and were of mild character and probably a consequence of associated intake of sodium bicarbonate buffer. Other events (7% skin eruptions, 2.7% fever) were mild and considered as harmless (or not vaccine related). The results show that the oral cholera vaccine CVD103HgR was well tolerated and accepted by travelers.

[Asylum seekers and refugees in general practice: problems and possible developments]

Health and health services provided to asylum seekers and refugees by the Swiss National Health System have so far not been systematically investigated. The aim of this cross-sectional study was to describe the attending asylum seekers and refugees demographically and clinically, to identify main problem areas as perceived by general practitioners and to highlight options and venues for improvements. 272 questionnaires have been filled in by GPs of eight "federal districts" (Kantone) and the consultations of 1477 asylum seekers and refugees have been documented during one month in 193 surgeries. The documented asylum seekers and refugees reflected the distribution of this population in Switzerland. Low consultation rates of asylum seekers and refugees in the majority of surgeries and high diversity of this population in respect to places of origin, education and proficiency in languages appear to be the major determinants of the difficulties in providing adequate health services to them. Readily available information on the past medical history and on the ethnic background of these patients and continuing education on specific topics concerning health care for asylum seekers and refugees were thought to be particularly useful. This needs to be considered in the planning of services for this group. General practitioners specialized in health care for asylum seekers and refugees is an option for providing improved specific services (interpreters, institutional links, culturally adapted medical care).

Vascular endothelial growth factor up-regulates its receptor fms-like tyrosine kinase 1 (FLT-1) and a soluble variant of FLT-1 in human vascular endothelial cells

The growth of solid tumors and the formation of metastases are dependent on neoangiogenesis. One of the most important factors in inducing the formation of new blood vessels is the vascular endothelial growth factor (VEGF), which acts specifically on endothelial cells. VEGF is expressed and secreted by almost all solid tumors. The molecular mechanisms leading to enhanced production of this angiogenic mitogen are manyfold and have been elucidated to some degree. Two VEGF receptors, fms-like tyrosine kinase 1 (FLT-1) and KDR, have been identified almost specifically on human endothelial cells. They are expressed preferentially in the proliferating endothelium of vessels lining and/or penetrating solid tumors, whereas they are almost undetectable by convenient methods in vessels of healthy tissue. However, the underlying mechanisms are not understood. We could show that media conditioned by various cancer cell lines grown under hypoxic conditions were able to up-regulate expression of FLT-1 mRNA and protein but not of KDR mRNA. Furthermore, up-regulation of a shorter mRNA species was observed that most probably codes for the soluble variant of FLT-1. These effects were completely inhibited by VEGF-neutralizing extracellular VEGF receptor domains. The effect could be mimicked by adding recombinant VEGF instead of conditioned cancer cell medium to the endothelial cell cultures. Both mutant VEGF, which activates only KDR, and placenta growth factor, which activates only FLT-1, were able to enhance FLT-1 expression. VEGF-stimulated FLT-1 mRNA expression was inhibited by actinomycin D. These data suggest that VEGF itself is the main factor secreted by tumor cells that is able to enhance the expression of its receptor FLT-1 and of a soluble variant of FLT-1 in endothelial cells.

High-dose sequential chemotherapy and autologous stem cell reinfusion in advanced pediatric solid tumors

Between January 1993 and December 1996, 21 children with advanced solid tumors were entered in a dose-escalating study of high-dose sequential chemotherapy followed by autologous stem cell transplantation. The diagnoses included neuroblastoma (NB) for 13 patients; Ewing's sarcoma (ES) for six patients and osteosarcoma for two patients. Nine patients received therapy as consolidation for primary metastatic disease, and 12 patients had had previous relapses. Treatment consisted of CY given i.v. at a dose of 7 g/m2 on day 1, followed by G-CSF until myeloid recovery. After 3 weeks of rest, all patients were given thiotepa i.v. on days 22-24. The total dose of thiotepa was 450 mg/m2 in three patients, 600 mg/m2 in six patients, and 750 mg/m2 in 12 patients. Melphalan was given i.v. at a dose of 180 mg/m2 i.v. on day 27 followed by stem cell infusion on day 28. Major toxic reactions included stomatitis, esophagitis, diarrhea and dermatitis. Three patients died of treatment-related complications. Twelve patients have had a relapse. Six patients (five with NB and one with ES) are alive in continuous remission 5-50 months (median 36) after transplantation. The results of this study show that it is feasible to administer high-dose sequential chemotherapy to children with advanced solid tumors.

Odor-guided fear conditioning in rats: 2. Lesions of the anterior perirhinal cortex disrupt fear conditioned to the explicit conditioned stimulus but not to the training context

Previous studies examining the neural substrates of fear conditioning have indicated unequivocally that the acquisition and expression of conditioned fear depends critically on the integrity of the amygdala. The extent to which the rhinal cortical areas contribute to fear conditioned to either the explicit conditioned stimulus (CS) or to the training context is less clear, however. The effects of pretraining lesions of the anterior perirhinal (PRH) cortex on fear conditioned to an explicit odor CS and to the context in which CS-unconditioned stimulus pairing took place was examined in rats. Rats with PRH cortex lesions demonstrated a robust attenuation of fear conditioned to the explicit CS, but no attenuation of fear conditioned to the training context. These data suggest that the PRH cortex is an important component of the neural system supporting the association between olfactory cues and footshock and add to a growing body of evidence implicating the rhinal cortical regions in associative learning.

Activity of four allelic forms of glutathione S-transferase hGSTP1-1 for diol epoxides of polycyclic aromatic hydrocarbons

Allelic forms of hGSTP1-1 which differ from each other by their catalytic properties and, structurally, by the amino acid(s) in position(s) 104 or (and) 113 are known to exist in human populations. The four possible isoforms of hGSTP1-1 with isoleucine or valine in position 104 and with alanine or valine in position 113 were produced by site-directed mutagenesis of the cDNA followed by bacterial expression and purification of the proteins. Glutathione-conjugating activity was measured with the diol epoxides of benzo(a)pyrene and chrysene, as well as with the model substrate 1-chloro-2,4-dinitrobenzene. Isoenzymes with valine in position 104 were more effective with the diol epoxides of polycyclic aromatic hydrocarbons but less effective with 1-chloro-2,4-dinitrobenzene than the isoforms with isoleucine 104. In addition, the transition A113V in the presence of V104 caused a pronounced increase in catalytic efficiency for the benzo(a)pyrene but not the chrysene diol epoxide. It is proposed that amino acid 113 functions as part of a clamp that lines the mouth of the water channel leading to the active sites of the hGSTP1-1 dimer and controls the access to substrates. Therefore, the hydrophobicity and the size of residue 113 are important in co-determining the substrate specificity of the isoenzymes. The widely different activities of the allelic isoforms toward carcinogenic diol epoxides of polycyclic aromatic hydrocarbons may help to explain the correlation between cancer susceptibility and genotype at the hGSTP1 locus that has been found by others.

Immunogenicity and protectivity of a new liposomal hepatitis A vaccine

In this study we investigated a new liposomal hepatitis A vaccine (Epaxal) developed by the Swiss Serum and Vaccine Institute clinically and immunologically using a one dose priming schedule and a booster injection after 1 year. This vaccine contains formalin inactivated hepatitis A virus particles attached to phospholipid vesicles together with influenza virus haemagglutinin. Two doses of the vaccine were administered at months 0 and 12 in 117 volunteers. Blood samples were drawn at days-7, 14 and 28 and after 6, 12 and 13 months, local and systemic reactions were monitored by means of questionnaires. Immunogenicity was evaluated as usual by the determination of anti-HAV from the collected sera using the ELISA technique. In order to evaluate the protective efficacy of the vaccine induced antibodies a sample of 25 sera mainly from vaccinees showing low ELISA titres was additionally analysed by means of a virus NT. The vaccine was excellently tolerable and highly immunogenic. Seroconversion evaluated by ELISA was 97 and 99%, respectively, 14 and 28 days after the first dose and 100% after the second dose. NT titres were well correlated with ELISA titres and showed similar seroconversion rates even in the early phase of immunization. The results of this study show that with two doses of the liposomal hepatitis A vaccine administered at months 0 and 12 early protection within 14 days and long lasting immunity can be achieved.