Computational Identification of Tumor Anatomic Location Associated with Survival in 2 Large Cohorts of Human Primary Glioblastomas

BACKGROUND AND PURPOSE

Tumor location has been shown to be a significant prognostic factor in patients with glioblastoma. The purpose of this study was to characterize glioblastoma lesions by identifying MR imaging voxel-based tumor location features that are associated with tumor molecular profiles, patient characteristics, and clinical outcomes.

MATERIALS AND METHODS

Preoperative T1 anatomic MR images of 384 patients with glioblastomas were obtained from 2 independent cohorts (n = 253 from the Stanford University Medical Center for training and n = 131 from The Cancer Genome Atlas for validation). An automated computational image-analysis pipeline was developed to determine the anatomic locations of tumor in each patient. Voxel-based differences in tumor location between good (overall survival of >17 months) and poor (overall survival of <11 months) survival groups identified in the training cohort were used to classify patients in The Cancer Genome Atlas cohort into 2 brain-location groups, for which clinical features, messenger RNA expression, and copy number changes were compared to elucidate the biologic basis of tumors located in different brain regions.

RESULTS

Tumors in the right occipitotemporal periventricular white matter were significantly associated with poor survival in both training and test cohorts (both, log-rank P < .05) and had larger tumor volume compared with tumors in other locations. Tumors in the right periatrial location were associated with hypoxia pathway enrichment and PDGFRA amplification, making them potential targets for subgroup-specific therapies.

CONCLUSIONS

Voxel-based location in glioblastoma is associated with patient outcome and may have a potential role for guiding personalized treatment.

Arterial spin-labeled perfusion of pediatric brain tumors

BACKGROUND AND PURPOSE

Pediatric brain tumors have diverse pathologic features, which poses diagnostic challenges. Although perfusion evaluation of adult tumors is well established, hemodynamic properties are not well characterized in children. Our goal was to apply arterial spin-labeling perfusion for various pathologic types of pediatric brain tumors and evaluate the role of arterial spin-labeling in the prediction of tumor grade.

MATERIALS AND METHODS

Arterial spin-labeling perfusion of 54 children (mean age, 7.5 years; 33 boys and 21 girls) with treatment-naive brain tumors was retrospectively evaluated. The 3D pseudocontinuous spin-echo arterial spin-labeling technique was acquired at 3T MR imaging. Maximal relative tumor blood flow was obtained by use of the ROI method and was compared with tumor histologic features and grade.

RESULTS

Tumors consisted of astrocytic (20), embryonal (11), ependymal (3), mixed neuronal-glial (8), choroid plexus (5), craniopharyngioma (4), and other pathologic types (3). The maximal relative tumor blood flow of high-grade tumors (grades III and IV) was significantly higher than that of low-grade tumors (grades I and II) (P < .001). There was a wider relative tumor blood flow range among high-grade tumors (2.14 ± 1.78) compared with low-grade tumors (0.60 ± 0.29) (P < .001). Across the cohort, relative tumor blood flow did not distinguish individual histology; however, among posterior fossa tumors, relative tumor blood flow was significantly higher for medulloblastoma compared with pilocytic astrocytoma (P = .014).

CONCLUSIONS

Characteristic arterial spin-labeling perfusion patterns were seen among diverse pathologic types of brain tumors in children. Arterial spin-labeling perfusion can be used to distinguish high-grade and low-grade tumors.

Normal sagittal and coronal suture widths by using CT imaging

BACKGROUND AND PURPOSE

Pediatric cranial sutures are often evaluated for abnormal diastasis upon presentation to the emergency department after trauma or during a neurologic consultation; however, few normative data for CT measurements exist. This study establishes normal means for the sagittal and coronal suture widths during the first year of life by using CT.

MATERIALS AND METHODS

The sagittal suture and bilateral coronal sutures were evaluated for 483 patients, ages 1 day to 395 days collected retrospectively from electronic medical records. Histograms as well as normality and boxplots were used to view the distribution of the data. An analysis of variance was performed for each suture measured by using month of age as the independent class variable.

RESULTS

The average proximal suture widths for the sagittal and coronal sutures at zero months of age were 5.0 ± 0.2 and 2.5 ± 0.1 mm, respectively. From zero to 1 month of age, these sutures narrowed significantly to 2.4 ± 0.1 and 1.3 ± 0.1 mm, respectively. From 1 to 12 months of age, sutures narrowed gradually. The proximal coronal suture widths showed a significant reduction from 1 month to 12 months (1.3 ± 0.1-0.8 ± 0.1 mm).

CONCLUSIONS

The normative values for suture widths established by CT scan among this large population may be used to assess the infant calvaria for suture diastasis.

The TUNEL assay consistently underestimates DNA damage in human spermatozoa and is influenced by DNA compaction and cell vitality: development of an improved methodology

The purpose of this study was to evaluate the terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) assay as a method for assessing DNA damage in human spermatozoa. The conventional assay was shown to be insensitive and unresponsive to the DNA fragmentation induced in human and mouse spermatozoa on exposure to Fenton reagents (H₂O₂ and Fe(2+) ). However, both time- and dose-dependent responses could be readily detected if the chromatin was exposed to 2 mm dithiothreitol (DTT) for 45 min prior to fixation. This modified version of the assay significantly enhanced the TUNEL signals generated by subpopulations of spermatozoa isolated on discontinuous Percoll gradients as well as the responses triggered by reagents (arachidonic acid and menadione) that are known to stimulate superoxide anion production by human spermatozoa. DTT exposure also improved the signals detected with chromomycin A₃ (CMA₃), a probe designed to determine the efficacy of chromatin protamination, and enhanced the correlation observed between this criterion of sperm quality and the TUNEL assay. Finally, the output of the TUNEL assay was found to be highly correlated with sperm vitality. The TUNEL methodology was therefore further refined to incorporate a vital stain that covalently bound to intracellular amine groups in non-viable cells. This tag remained associated with the spermatozoa during fixation and processing for the TUNEL assay so that ultimately, both DNA integrity and vitality could be simultaneously assessed in the same flow cytometry assay. The methods described in this article are simple and robust and should facilitate research into the causes of DNA damage in human spermatozoa.

Analysis of chaperone proteins associated with human spermatozoa during capacitation

Mammalian spermatozoa must undergo a post-ejaculatory period of maturation, known as capacitation, before they can engage in the process of fertilization. Studies in the mouse have established that capacitation facilitates sperm-zona recognition via mechanisms that involve the appearance of tyrosine phosphorylated chaperone proteins on the sperm surface overlying the acrosome, the site of sperm-zona recognition. In this study, we examined whether a similar relationship existed between the tyrosine phosphorylation events associated with capacitation and sperm-zona interaction in human spermatozoa. These studies confirmed that capacitation is associated with an increase in both sperm-zona binding and an increase in tyrosine phosphorylation over the sperm tail. However, we could not detect the surface expression of phosphotyrosine residues over the sperm head, as observed with murine spermatozoa. Moreover, although we could clearly detect a number of chaperone proteins in human spermatozoa including HSPE1, DNAJB1, HSPD1, HSPA1A, HSPCA, HSPH1, HSPA5 and TRA1, none of these molecules were expressed on the sperm surface. On the basis of these results, it is unlikely that these proteins play an active role in the remodeling of the sperm surface during capacitation. We conclude that strong species-specific differences exist in the molecular mechanisms that drive sperm-egg recognition and that alternative, chaperone-independent, mechanisms must underpin sperm-zona interaction in the human.

New-onset temporal lobe epilepsy in children: lesion on MRI predicts poor seizure outcome

OBJECTIVE

To determine factors predictive of long-term seizure outcome in children with new-onset temporal lobe epilepsy (TLE).

METHODS

A community-based cohort of 77 children with new-onset TLE, including 14 with possible TLE, were followed prospectively with formal review 7 and 14 years following seizure onset. Diagnoses were re-evaluated at each review, and changed when new clinical, EEG, or imaging data were compelling.

RESULTS

Sixty-four patients sustained the diagnosis of TLE over time; two were lost to follow-up. Age at follow-up was 12 to 29 years (median 20 years). Median follow-up was 13.7 years, 95% being followed for greater than 10 years. Nineteen patients were seizure free (SF) and off treatment, having not had seizures for 5 to 15 years. Duration of active TLE in the SF group was 1 to 8 years, the children being treated with 0 to 3 antiepileptic drugs (AEDs). Forty-three patients were not seizure free (NSF) and had ongoing seizures or had undergone epilepsy surgery. These children were treated with 1 to 10 AEDs. Fifteen NSF patients experienced 22 nonterminal seizure remissions of 1 to 7 years duration. Seventeen children had a significant antecedent to TLE. Lesions were identified on neuroimaging in 28 and included hippocampal sclerosis (HS) in 10, tumor in 8, and dysplasia in 7. All children with lesions on MRI were NSF (p < 0.001). Focal slowing on EEG was also associated with persistent seizures (p = 0.05), although this was correlated with a lesion on MRI. Infantile onset of epilepsy, family history of seizures, initial seizure frequency, antecedents, and early seizure remissions were not predictive of seizure outcome.

CONCLUSION

Seizures spontaneously remit in approximately one third of children with new-onset TLE. A lesion on MRI predicts intractable seizures in TLE and the potential need for epilepsy surgery.

Mucosal immunization against hepatitis A: antibody responses are enhanced by co-administration of synthetic oligodeoxynucleotides and a novel cationic lipid

Hepatitis A caused by hepatitis A virus (HAV) transmitted by the fecal-oral route, results in considerable morbidity and economic loss. Mucosal immunization can be more effective than conventional injection at inducing both local and systemic immunity to HAV. Here we show that co-administration of killed HAV with synthetic oligodeoxynucleotides (ODNs) containing CpG sequences, and a novel polycationic sphingolipid (CCS)/cholesterol liposomal delivery system, markedly enhances the HAV-specific antibody response at the intestinal interface, particularly when delivered intrarectally or intranasally, to Balb/c mice at low HAV doses. A mucosally delivered, antigen-sparing HAV vaccine that is easily administered without specialized equipment or personnel, is an attractive alternative for facilitating mass immunization in hepatitis A outbreaks.

Multiple adaptive mechanisms to chronic liver disease revealed at early stages of liver carcinogenesis in the Mdr2-knockout mice

Molecular events preceding the development of hepatocellular carcinoma were studied in the Mdr2-knockout (Mdr2-KO) mice. These mice lack the liver-specific P-glycoprotein responsible for phosphatidylcholine transport across the canalicular membrane. Portal inflammation ensues at an early age followed by hepatocellular carcinoma development after the age of 1 year. Liver tissue samples of Mdr2-KO mice in the early and late precancerous stages of liver disease were subjected to histologic, biochemical, and gene expression profiling analysis. In an early stage, multiple protective mechanisms were found, including induction of many anti-inflammatory and antioxidant genes and increase of total antioxidant capacity of liver tissue. Despite stimulation of hepatocyte DNA replication, their mitotic activity was blocked at this stage. In the late stage of the disease, although the total antioxidant capacity of liver tissue of Mdr2-KO mice was normal, and inflammation was less prominent, many protective genes remained overexpressed. Increased mitotic activity of hepatocytes resulted in multiple dysplastic nodules, some of them being steatotic. Expression of many genes regulating lipid and phospholipid metabolism was distorted, including up-regulation of choline kinase A, a known oncogene. Many other oncogenes, including cyclin D1, Jun, and some Ras homologues, were up-regulated in Mdr2-KO mice at both stages of liver disease. However, we found no increase of Ras activation. Our data suggest that some of the adaptive mechanisms induced in the early stages of hepatic disease, which protect the liver from injury, could have an effect in hepatocarcinogenesis at later stages of the disease in this hepatocellular carcinoma model.

Identification of the sex-determining locus of Atlantic salmon (Salmo salar) on chromosome 2

We have integrated data from linkage mapping, physical mapping and karyotyping to gain a better understanding of the sex-determining locus, SEX, in Atlantic salmon (Salmo salar). SEX has been mapped to Atlantic salmon linkage group 1 (ASL1) and is associated with several microsatellite markers. We have used probes designed from the flanking regions of these sex-linked microsatellite markers to screen a bacterial artificial chromosome (BAC) library, representing an 11.7x coverage of the Atlantic salmon genome, which has been HindIII fingerprinted and assembled into contigs. BACs containing sex-linked microsatellites and their related contigs have been identified and representative BACs have been placed on the Atlantic salmon chromosomes by fluorescent in situ hybridization (FISH). This identified chromosome 2, a large metacentric, as the sex chromosome. By positioning several BACs on this chromosome by FISH, it was possible to orient ASL1 with respect to chromosome 2. The region containing SEX appears to lie on the long arm between marker Ssa202DU and a region of heterochromatin identified by DAPI staining. BAC end-sequencing of clones within sex-linked contigs revealed five hitherto unmapped genes along the sex chromosome. We are using an in silico approach coupled with physical probing of the BAC library to extend the BAC contigs to provide a physical map of ASL1, with a view to sequencing chromosome 2 and, in the process, identifying the sex-determining gene.

Structural abnormalities remote from the seizure focus: a study using T2 relaxometry at 3 T

OBJECTIVE

To determine the extent and severity of mesial temporal and subcortical signal abnormalities in patients with partial epilepsy.

METHODS

T2 relaxation time maps were acquired in 50 consecutive patients and 55 control subjects on a 3 T MRI scanner. Twenty-two patients had hippocampal sclerosis (HS), 16 had malformations of cortical development (MCD), and 12 had no obvious MR abnormalities (normal MR). The following eight regions were measured bilaterally: hippocampus, anterior temporal lobe (ATL) white matter, amygdala, frontal lobe white matter, caudate, putamen, pallidum, and thalamus.

RESULTS

In patients with HS, increased T2 relaxation times were found in the ipsilateral hippocampus and ATL but not in subcortical nuclei. In patients with MCD, increased T2 relaxation times were found in the temporal lobe (hippocampus, ATL) and in subcortical areas (caudate, putamen, and pallidum); in patients with normal MR, increased T2 relaxation times were found in the hippocampus and putamen. The degree of abnormality did not correlate with the duration of epilepsy or the estimated seizure load.

CONCLUSIONS

Mesial temporal structures show increased T2 relaxation times not only in patients with hippocampal sclerosis but also in patients with a seizure focus remote from the hippocampus. Patients with normal MR and focal malformations of cortical development have increased T2 relaxation times in subcortical structures. Therefore, abnormalities in T2 relaxation time can be found remote from the seizure focus. They cannot be simply attributed to secondary seizure effects.

Hypertensive encephalopathy: antecedent to hippocampal sclerosis and temporal lobe epilepsy?

The authors describe three patients with refractory temporal lobe epilepsy (TLE) following an episode of hypertensive encephalopathy as their only identified antecedent event. All patients had typical MR features of hippocampal sclerosis (HS), and the two operated cases had typical HS histology and became seizure-free postoperatively. These cases suggest that hypertensive encephalopathy may be a rare form of initial precipitating injury, leading to TLE and HS.

Rectal immunization of mice with hepatitis A vaccine induces stronger systemic and local immune responses than parenteral immunization

Systemic (spleen cell (SPLC), serum antibodies) and intestinal mucosal (Peyer's patch cells (PPC), lamina propria lymphocytes (LPLs), coproantibodies) immune responses were compared in mice immunized with varying doses (144, 72, 36, 18 ELISA units [EU]) of HAVRIX, an alum-adsorbed killed hepatitis A virus (HAV) vaccine, delivered either intrarectally (i.r.) or intraperitoneally (i.p.) in three doses at weekly intervals. HAV-specific IgG, IgM, and IgA antibody responses were evaluated by ELISPOT and EIA and HAV-responsive lymphocytes by lymphocyte stimulation assays. Systemic IgG responses were greater in mice immunized intraperitoneally with 144, 72, and 36EU of HAVRIX, while IgM and IgA responses were greater in PPC and LPL cell populations, serum and coproantibodies of rectally immunized mice, particularly at HAVRIX doses of 36 and 18EU. Rectal immunization at lower doses (36, 18EU) also elicited strong cellular responses in all cell populations while parenteral (i.p.) vaccination, did not. Results suggest that rectal immunization may be a highly effective way of inducing both local and systemic immunity to HAV.

Parvovirus B19 nonstructural (NS1) protein as a transactivator of interleukin-6 synthesis: common pathway in inflammatory sequelae of human parvovirus infections?

This review focuses on the role that human parvovirus B19 nonstructural (NS1) protein as a transactivator of the proinflammatory cytokine, interleukin-6 (IL-6), might play in triggering the multiparametric inflammatory outcomes of B19 infection. Parvovirus B19 is a ubiquitous virus, and it is often expressed during conditions of immunodepression including that induced by long-term chemotherapy, viral infection (HIV, HTLV-1), or genetic immunodeficiency disorders. Through NS1 expression, B19 may contribute to the immune dysregulation associated with these disorders, or serve as a cofactor in enhancing retroviral replication. Hence, NS1 transactivation of proinflammatory cytokine promoters such as IL-6 may be pivotal in triggering the various inflammatory and autoimmune disorders that have been linked to parvovirus B19 infections.

Linoleic acid prevents chloride influx and cellular lysis in rabbit renal proximal tubules exposed to mitochondrial toxicants

Despite many studies elucidating the mechanisms of necrotic cell death, the role of fatty acids released during necrosis remains to be determined. The goals of this study were to determine whether linoleic acid could protect rabbit renal proximal tubules (RPT) from necrotic cell death associated with mitochondrial dysfunction and oxidative injury and to determine the mechanisms involved. Exposure to antimycin A (10 microM) for 1 h or hypoxia (perfusion with 95% N(2)/5% CO(2)) for 1 or 2 h induced approximately 70% cellular lysis, as measured by lactate dehyrogenase release, versus 10% in controls. Preincubation with linoleic acid (100 microM) fully protected RPT from cellular lysis. RPT were also protected from lysis if linoleic acid was added 15 min after the addition of antimycin A. Measurements of free intracellular Ca(2+) concentrations showed that linoleic acid did not prevent the rise in intracellular Ca(2+) associated with a 30-min exposure to antimycin A. However, the influx of extracellular (36)Cl(-) following a 30-min exposure to antimycin A was ameliorated in the presence of linoleic acid. Linoleic acid did not prevent cellular lysis after exposure to hypoxia/reoxygenation (1 h/1 h) or t-butyl hydroperoxide (500 microM, 3 h). These data suggest that linoleic acid protects RPT during the late phase of cell death associated with inhibition of the electron transport chain but not oxidative injury. Several other fatty acids also protected RPT from lysis, and structure-activity relationship studies suggest that a free carboxyl terminus and at least one double bond are required for this action.

Lymphocyte recognition of human parvovirus B19 non-structural (NS1) protein: associations with occurrence of acute and chronic arthropathy?

Immune recognition of recombinant parvovirus B19 non-structural (rNS1) protein was studied by immunoblot and lymphoproliferative assays in blood from the following B19 seropositive groups: B19 infected (n = 14), B19 exposed but non-infected (n = 16), other illness with rash (n = 3), chronic arthropathy of unknown aetiology (n = 4) and healthy controls (n = 7). Sera from 11 B19 seronegative subjects were also studied. Sera collected at initial diagnosis or at the time of accidental B19 exposure in pregnancy were tested for NS1 antibody and evidence of B19 DNA by nested PCR. Follow-up specimens were obtained 3-12 months later for serological, PCR and proliferation studies. B19 DNA was detected sporadically in early specimens and in one follow-up specimen from a subject who developed chronic arthropathy after B19 infection. There was no correlation with development of arthropathy. NS1-specific IgG was detected in early sera from B19-infected and exposed subjects but to a lesser degree in follow-up specimens, and in only one healthy control serum. No correlation with the presence of NS1-specific antibodies was found with development of acute or chronic arthropathy. Although lymphocyte proliferation in response to stimulation with rNS1 in vitro occurred at a higher frequency in patients who developed acute and chronic joint manifestations after B19 infection, suggesting an association with this outcome, NS1-reactive lymphocytes were also found in three B19 seronegative patients, two of whom had recently been exposed to B19 but had no illness. Hence, immune recognition of NS1 may be more indicative of recent infection with, or exposure to, parvovirus B19 than associated with development of arthropathy as previously reported.

Near-total absence of the cerebellum

We report five cases of near-total absence of the cerebellum with accompanying pontine hypoplasia. The cerebellar remnant in each case comprised only antero-superior masses, the posterior fossa being otherwise fluid filled. Three of these patients, two teenagers and an infant, presented a fairly consistent clinical and neuroradiological phenotype, and a few similar cases are recorded in the literature. The cerebellar remnant was irregular and asymmetrical, and no ventral pontine prominence was discernible. In at least the older two, cerebellar motor functions were not greatly compromised, and intellectual handicap was of a mild degree. We propose that these cases represent a distinct entity of "near-total absence of the cerebellum with flat ventral pons, and relatively mild clinical affection". All cases have been sporadic, implying that the risk of recurrence within a family may be low. Quite different clinical pictures, of considerably greater severity, are demonstrated in the remaining two cases. One had pontocerebellar hypoplasia type 2, while the other had a complex cerebellar and cerebral malformation.

Defining mechanisms of toxicity for linoleic acid monoepoxides and diols in Sf-21 cells

Linoleic acid monoepoxides have been correlated with many pathological conditions. Studies using insect cells derived from Spodoptera frugiperda (Sf-21 cells) have suggested that conversion of the epoxides to the diols is required for toxicity. However, more recent studies using rabbit renal proximal tubules have suggested that linoleic acid monoepoxides are direct mitochondrial toxins. To better understand these discrepancies, we compared the toxicity of these linoleic acid metabolites in Sf-21 cells using mitochondrial respiration as an end point. Linoleic acid (100 microM) and 12,13-epoxy-9-octadecenoic acid (12,13-EOA, 100 microM) increased the rate of oligomycin-insensitive respiration by approximately 3.5- and 3-fold, respectively, decreased the rate of oligomycin-sensitive respiration by approximately 52 and 68%, respectively, and had no effect on the integrity of the electron transport chain. These effects were concentration-dependent, occurred within 1 min, and recovered to basal levels within 45 min. 12,13-Dihydroxy-9-octadecenoic acid (12,13-DHOA, 100 microM) had no effect on oligomycin-insensitive respiration but decreased the rate of oligomycin-sensitive respiration and uncoupled respiration in a concentration-dependent manner. Approximately 79 and 68% of oligomycin-sensitive respiration and uncoupled respiration was inhibited by 12,13-DHOA (100 microM), respectively. These effects occurred within 1 min and were not reversible in 6 h. Effects similar to those induced by 12,13-DHOA (100 microM) were observed using 12,13-EOA (100 microM) in Sf-21 cells expressing human soluble epoxide hydrolase. These data suggest that in this Sf-21 model linoleic acid and linoleic monoepoxides have transient uncoupling effects, whereas the primary mechanism of toxicity for linoleic acid diols in this model is inhibition of the electron transport chain.

Analysis of the cytotoxic properties of linoleic acid metabolites produced by renal and hepatic P450s

Cytochrome P450 epoxidation of linoleic acid produces biologically active metabolites which have been associated with many pathological conditions that often lead to acute renal failure. In the present study, we evaluated the ability of specific cytochrome P450s to produce linoleic acid monoepoxides. We then tested the cytotoxic properties of linoleic acid, linoleic acid monoepoxides, and corresponding diols in a rabbit renal proximal tubule model. CYP1A2, CYP2E1, CYP2J2, CYP2J3, CYP2J5, and CYP2J9 metabolized linoleic acid at rates comparable to arachidonic acid and produced linoleic acid monoepoxides as major products. Cytotoxicity studies showed that linoleic acid, linoleic acid monoepoxides, and corresponding diols are toxic at pathologically relevant concentrations (100-500 microM). Concentration-dependent studies showed that linoleic acid and linoleic acid monoepoxides are the most toxic and induce mitochondrial dysfunction prior to cell death. Cytoprotectants known to block cell death associated with mitochondrial dysfunction and oxidative stress did not prevent cell death induced by linoleic acid and linoleic acid monoepoxides. This study shows that P450s in the CYP1 and CYP2 gene families metabolize linoleic acid to linoleic acid monoepoxides and that the monoepoxides, as well as linoleic acid, disrupt mitochondrial function without causing oxidative stress.

Cross-reactive rubella virus and glutamic acid decarboxylase (65 and 67) protein determinants recognised by T cells of patients with type I diabetes mellitus

AIMS/HYPOTHESIS

To examine the cross-reaction between viral and beta-cell protein determinants and to further understand the potential role of this mechanism in Type I (insuline-dependent) diabetes mellitus.

METHODS

Immune responses to a panel of 28 viral and beta-cell protein peptides representing selected sequences of rubella virus (RV), Coxsackie virus, human 38 KDa31G and glutamic acid decarboxylase (GAD 65 and 67) proteins in proliferation or cytotoxicity assays have been studied using uncloned and cloned T-cell cohorts from a group of 60 Type I diabetic patients.

RESULTS

Peptide GAD65(252-266) induced the responses of patients with recent onset diabetes in proliferation assays at the highest frequency (77%), whereas GAD67(212-226) stimulated the cellular responses at the highest rate (61%) in patients with late-onset diabetes. RVE1(157-176) was recognised by all groups of patients at the highest frequency and the largest amplitude among the viral peptides tested. T-cell clones specific to GAD65(252-266), GAD65(274-286) or GAD67(212-226) were tested in cytotoxicity assays for their responses to rubella virus peptides. Each of these T-cell clones cross-reacted with two to four rubella virus peptides, including RVE1(157-176) and RVE2(87-107). Analysis of the sequences of cross-reactive viral and glutamic acid decarboxylase antigens showed that these epitopes shared similar peptide binding motifs to HLA DR3/DR4. There is a statistically significant correlation between the response amplitude of patient's peripheral blood mononuclear cells to RVE1(157-176), RVE2(87-107) and GAD65(274-286) in patients with recent onset diabetes, and to RVE1(157-176) and GAD67(212-226) in patients with late onset diabetes.

CONCLUSION/INTERPRETATION

Cross-reactive glutamic acid decarboxylase and rubella virus determinants identified by T-cell clones were also recognised at high frequencies by general T-cell populations of Type I diabetic patients.

Hippuric acid as a major excretion product associated with black tea consumption

1. Nine habitual tea-drinking volunteers were recruited and asked to follow a low-polyphenol and low-caffeine diet for 6 days and to provide daily 24-h urine samples. On day 4 of the experiment strong black tea brewed under standardized conditions was re-introduced to the volunteers' diet. 2. 1H-NMR and HPLC profiling of the urine samples indicated that consumption of black tea (6-10 mugs per day) was associated with a significant (p = 0.00017) increase in hippuric acid excretion relative to control, increasing from 153-512 to 742-1374 mg day(-1). The excretion of substantial amounts of hippuric acid has not previously been associated with black tea consumption. 3. For some volunteers, the quantity of benzoic acid processed exceeded the acceptable daily intake (ADI), but this is not considered to constitute any hazard. 4. A mass-balance analysis indicated that the necessary quantity of benzoic acid could not be obtained from the contents of gallic acid, flavanols, flavonol glycosides and theaflavins in black tea even if 100% transformation was obtained, suggesting that the thearubigins (the major and chemically ill-defined polyphenols of black tea) may be an important source.

Rubella virus vaccine associated arthropathy in postpartum immunized women: influence of preimmunization serologic status on development of joint manifestations

OBJECTIVE

To measure preimmunization rubella virus (RV)-specific IgG levels and to relate these to the development of acute and chronic (persistent or recurrent) joint manifestations following rubella vaccination.

METHODS

Specific IgG was determined by whole RV enzyme immunoassays (EIA) (Abbott Rubazyme and M33, an in-house method), immunoblot, neutralization domain peptide (BCH-178c) EIA, and neutralization bioassay in prevaccine samples of 268 RV seronegative women (Abbott absorbance < 0.999 units) who had received monovalent live attenuated RA27/3 strain RV vaccine in a clinical trial that recorded joint manifestations.

RESULTS

Of rubella vaccinated women tested for prevaccine antibodies, 21.7% were actually positive (> or = 10 IU/ml) by M33 EIA, 33.2% had Abbott values > or = 0.250 units, and 47.6% had RV protein-specific antibody (immunoblot), while only 17.6% were positive (> or = 10 IU/ml) by neutralization domain peptide EIA and 12.7% had neutralization titers > or = 1:8. Seropositivity by the various methods was compared to recorded occurrence of acute and chronic arthropathy (arthralgia and/or arthritis) after RV vaccination. Relative to women who had no joint manifestations, prevaccine seropositivity rates for subjects with acute arthropathy were significantly (p < 0.05) lower in the Abbott test (< 0.250 units), BCH-178c peptide EIA, and neutralization bioassay, while those who also developed chronic arthropathy had significantly lower prevaccine seropositivity rates for the Abbott (< 0.250 units) and M33 EIA and neutralization bioassay.

CONCLUSION

Results suggest that risk for arthropathy following RA27/3 rubella vaccination may be higher in women who have very low prevaccine levels of antibody, particularly in assays measuring functional (neutralizing) antibodies.

Antenatal diagnosis of subependymal heterotopia

Subependymal heterotopia consist of gray matter nodules along the lateral ventricular walls and are associated with epilepsy and other cerebral malformations. Some cases have an X-linked inheritance, and early antenatal diagnosis of affected fetuses is important for appropriate management. We present a case of heterotopia diagnosed by sonography and MR imaging at 23 weeks' gestation and discuss the differential diagnosis, reviewing the evolution and imaging appearances of the germinal matrix and its implications for detection of heterotopia.

Occurrence of hippocampal sclerosis: is one hemisphere or gender more vulnerable?

PURPOSE

We analyzed a large group of patients investigated for suspected seizures to test whether gender or side are important factors in the origins of hippocampal sclerosis (HS).

METHODS

We studied 996 consecutive patients (48% men, 52% women) by using standard hippocampal T2-relaxometry methods.

RESULTS

HS was associated with a highly abnormal T2 time (< or =113 ms). Categoric analysis showed that hippocampal T2 time was independent of gender and side. T2 time was bilaterally normal in 81% of men and in 79% of women; it was unilaterally abnormal in 15% of both men and women; and bilaterally abnormal in 4% of men and in 6% of women. Highly abnormal T2 relaxometry, suggesting HS, occurred with equal frequency in men and women and on the right and left sides. Quantitative analysis of hippocampal T2 times showed values not differing significantly between men and women or between the right and left hemispheres. There was no significant interaction between gender and side.

CONCLUSIONS

In patients with seizure disorders, hippocampal T2 relaxometry is not different in adult men and women and in the right and left hemispheres.

Identification of rubella virus T-cell epitopes recognized in anamnestic response to RA27/3 vaccine: associations with boost in neutralizing antibody titer

Rubella virus (RV)-specific cell-mediated immunity (CMI) and antibodies were measured in healthy adolescents reimmunized with measles-mumps-rubella (MMR) vaccine. Lymphocyte proliferation to RV synthetic peptides was determined before and at 2, 4 and 10 weeks after, MMR. After MMR, increased CMI was observed with 16 peptides, including six containing antibody neutralization (NT) domains. Positive CMI (stimulation index > or =2.0) to E1(254-285) and C(1-29) before vaccination was significantly associated with a boost in NT titers, while positive CMI at weeks 2 or 4 to E1(254-285), E1(301-314), E1(389-408), E1(462-481), E2(134-150), E2(140-156), E2(168-179), C(1-29) and C(88-111) showed the same association.

Anterior temporal abnormality in temporal lobe epilepsy: a quantitative MRI and histopathologic study

OBJECTIVE

To examine the nature and frequency of anterior temporal lobe (AT) abnormalities that occur in intractable temporal lobe epilepsy (TLE).

METHODS

We reviewed the MR scans and clinical histories of 50 consecutive patients with intractable TLE. Histopathology was available in 42 surgically treated cases.

RESULTS

MRI demonstrated loss of the gray-white matter differentiation and decreased T1- and increased T2-weighted signal in the ipsilateral AT in 58% of the 50 patients. This appearance was observed in 64% of the 36 patients with hippocampal sclerosis (HS) but was also seen in patients without HS. These changes were associated with temporal lobe atrophy, a higher hippocampal T2 relaxation time, and a history of febrile convulsions. Pathologic examination showed that the MRI appearances were not caused by dysplasia, degenerative abnormalities, or inflammatory change. Histologic quantitation showed increased glial cell nuclei counts in the intractable TLE cases compared with controls. There was no difference in glial cell numbers between cases with AT abnormality and those without this appearance. Presence or absence of changes was not predictive of preoperative neuropsychology, postoperative change in neuropsychology, or seizure outcome after surgery.

CONCLUSIONS

These frequently seen ipsilateral changes are not caused by gliosis and may reflect a nonspecific increase in water content in the temporal lobe. This may be due to myelin abnormalities or some other as yet unidentified pathologic factor.

Point mutation of a rubella virus E1 protein T-cell epitope by substitution of single amino acid reversed the restrictive HLA-DR polymorphism: a possible mechanism maintaining HLA polymorphism

The influence of single amino acid substitutions within a rubella E1 protein T-cell epitope, E1(273-284) on T-cell recognition was studied. Substitutions of an uncharged amino acid A for an E or for a T and substitution of a T for S were found to not significantly reduce the T-cell responses. However, substitution of a charged residue such as E for hydrophobic residues (I, V, or W); D for Q; or a relatively larger size amino acid for polar residues completely abolished the cytotoxicities mediated by E1(273-284)-specific T-cell clone. A set of single amino acid-substituted peptide analogs of E1(273-284) not eliciting cytotoxicity of the T-cell clone was used to test the influence of point mutation of the epitope on HLA DR restrictions. A panel of B-cell lines with different DR4 subtypes was used as targets in cytotoxicity assays to determine the restrictive HLA molecules. Results showed that modification of the T-cell epitope by point mutation could reverse the HLA DR restriction from one allele to other alleles. A model based on these results has been proposed to explain the mechanism balancing major histocompatibility complex (MHC) polymorphism in outbred populations.

A new categorization of HLA DR alleles on a functional basis

In this analysis, we introduce a new categorization of HLA DR alleles which are important members of HLA class II genes encoding cell surface glycoproteins that function to present antigenic peptides to T cells. We have grouped all HLA DR molecules into seven different functional categories on the basis of their ability to bind and present antigenic peptides to T cells and their association with susceptibility or resistance to disease. This novel categorization of DR alleles on the basis of function allows for the prediction of seven similar subregion structures (supertypes or supermotifs) within pocket 4 of HLA DR peptide binding groove as the molecular basis for grouping these alleles. The physicochemical characteristics of HLA DR supertype residues, charge in particular, may influence the selectivity for binding peptide, dominate promiscuous T-cell recognition of antigenic peptides, and affect HLA DR disease associations. To rationalize the functional categories of DR alleles, we have further combined the seven DR supertype patterns into three groups based on the charges of residues within the supertypes. Grouping HLA DR alleles into functional categories may assist in understanding the mechanistic basis of autoimmunity, resolving current paradoxes in HLA disease associations, and developing new immunotherapy strategies.

Epileptology of the first-seizure presentation: a clinical, electroencephalographic, and magnetic resonance imaging study of 300 consecutive patients

BACKGROUND

Prognosis and treatment of the first seizure depends on identification of a specific epilepsy syndrome, yet patients with first seizures are generally regarded as a homogeneous group. We studied whether it is possible to diagnose specific epilepsy syndromes promptly by use of standard clinical methods, electroencephalography (EEG) and magnetic resonance imaging (MRI).

METHODS

300 consecutive adults and children presented with unexplained seizures. We systematically collected clinical data from patients and witnesses, and attempted to obtain an EEG within 24 h of the seizure. Where the EEG was negative, a sleep-deprived EEG was done. MRI was done electively.

FINDINGS

A generalised or partial epilepsy syndrome was clinically diagnosed in 141 (47%) patients. Subsequent analysis showed that only three of these clinical diagnoses were incorrect. Addition of the EEG data enabled us to diagnose an epilepsy syndrome in 232 (77%) patients. EEG within 24 h was more useful in diagnosis of epileptiform abnormalities than later EEG (51 vs 34%). Neuroimaging showed 38 epileptogenic lesions, including 17 tumours. There were no lesions in patients for whom generalised epilepsy was confirmed by EEG. Our final diagnoses were: generalised epilepsy (23% of patients); partial epilepsy (58%); and unclassified (19%).

INTERPRETATION

An epilepsy syndrome can be diagnosed in most first-seizure patients. Ideally, an EEG should be obtained within 24 h of the seizure followed by a sleep deprived EEG if necessary. MRI aids diagnosis and should be done for all patients except for those with idiopathic generalised epilepsies and for children with benign rolandic epilepsy.

Serologic responses to measles, mumps, and rubella (MMR) vaccine in healthy infants: failure to respond to measles and mumps components may influence decisions on timing of the second dose of MMR

Measles, mumps, and rubella-specific IgG antibodies were evaluated in 134 healthy infants routinely immunized with trivalent live attenuated measles-mumps-rubella (MMR) vaccine at one year of age. Blood samples were collected just before, and at 1, 3, and 12 months after MMR. Specific IgG was measured by commercial enzyme immunoassays. Before vaccination, 98.5%, 99.2%, and 98.5% of the infants tested were seronegative for measles, mumps, and rubella, respectively. One year after MMR, 16.4% and 22.4% of vaccinees lacked demonstrable antibody to measles and mumps while none were found to be seronegative for rubella. Response profile analysis revealed primary failure rates of 12.1% (measles) and 8.6% (mumps) while 4% (measles) and 13.8% (mumps) of the infants responded initially but became seronegative within one year. These observations suggest that earlier administration (at age 18 months) of the second dose of MMR may be more desirable than revaccination at school entry.

Experience with diffusion-weighted imaging in an acute stroke unit

We performed diffusion-weighted MRI (DWI) on a standard 1.5-tesla MRI scanner using a high-speed stimulated echo pulse sequence (turboSTEAM) in 9 stroke patients and 9 control subjects to investigate whether this technique can be used clinically to assist in ischaemic stroke diagnosis within the time frame for potential therapy. Stroke patients underwent DWI between 3.75 h and 3 days after stroke onset. Three patients were studied on more than one occasion. DWI was normal in the 9 controls. Seven of 9 stroke patients showed areas of increased signal on DWI. DWI detected cerebral ischaemia 3.75 h after stroke onset when both CT and T2-weighted MRI were normal. In 6 DWI-positive patients studied at later times, increased signal on T2-weighted images was present at the same time. Two patients had normal CT, T2-weighted and DWI images; both made good neurological recoveries. For the routine assessment of stroke patients, DWI implemented on a standard MRI system can provide additional information of clinical value to that obtained with conventional pulse sequences. In particular it facilitates early detection of cerebral ischaemia during the first few hours after stroke.

Promiscuous T-cell recognition of a rubella capsid protein epitope restricted by DRB1*0403 and DRB1*0901 molecules sharing an HLA DR supertype

Two T cell clones derived from different donors with HLA-DRB1*0403 or DRB1*0901 phenotype recognize a rubella capsid peptide, C(265-273) in the context of several different HLA-DR molecules in addition to DRB1*0403 and DRB1*0901. All DR molecules restricting the T-cell clones have in common residues, R or Q at position beta 70, R at position beta 71, and E at position beta 74 in pocket '4' of the DR peptide binding groove, suggesting that a DR subregion structure or supertype, "Q/RRE" underlies the promiscuous T-cell recognition of this peptide. Single amino acid substituted analogs of peptide C(263-275) at anchor position 4 for natural residue R were tested for their ability to induce clonal T-cell cytotoxic responses. The results indicated that a positively charged residue, R or K, was required for T-cell recognition, suggesting a possible mechanism of electrostatic interactions between the negatively charged residue E at position beta 74 of these DR molecules and the positively charged residue at anchor position 4 of the peptide in T-cell recognition.

HLA-DR class II associations with rubella vaccine-induced joint manifestations

HLA class II (HLA-DR) frequencies were examined in relation to incidence of acute arthralgia or arthritis in 283 white women who had received RA27/3 rubella vaccine (n = 146) or placebo (n = 137) postpartum. Leukocyte DNA was molecularly typed for HLA-DRB1 gene expression. Univariate analysis revealed higher frequencies of DR2 (odds ratio [OR], 4.8; 95% confidence interval [CI], 1.2-18.8) and DR5 (OR, 7.5; 95% CI, 1.5-37.5) but lower frequencies of DR4 (OR, 2.3; 95% CI, 1.1-4.9) and DR6 (OR, 2.8; 95% CI, 1.4-5.8), in rubella vaccinees compared with placebo recipients with arthropathy. Logistic regression modelling of DR, treatment, age, time postpartum, and arthropathy revealed that the odds of developing arthropathy was 1.9 times greater (95% CI, 1.07-3.44) after rubella vaccine than placebo. Risk for arthropathy (regardless of rubella vaccination) was also influenced by DR interactions: odds were 8 times greater in individuals with both DR1 and DR4 (95% CI, 1.45-44.02) and 7.1 times greater with both DR4 and DR6 present (95% CI, 1.85-27.52), suggesting that coexpression of these specificities may predispose to postpartum arthropathy.

Characterization of an overlapping CD8+ and CD4+ T-cell epitope on rubella capsid protein

A synthetic peptide corresponding to rubella virus capsid protein residues 263 to 275 which contains an epitope recognized by a cloned CD4+ cytotoxic T-lymphocyte (CTL) line was used to induce CD8+ T-cell lines specific to this peptide. A peptide-specific CD8+ CTL clone was derived and characterized. This peptide-specific CD8+ CTL clone exhibited cytotoxicity against target cells infected by a vaccinia recombinant virus expressing rubella virus capsid protein, but not by target cells infected by vaccinia recombinant virus expressing rubella virus E1 or E2 envelope proteins. Analysis of HLA class I restriction of the CD8+ CTL clone revealed that A11 and A3 were restrictive elements. Fine mapping with truncated and overlapping peptide analogs revealed a nonamer sequence, C(264-272), as the T-cell epitope eliciting stronger cytotoxicity. Two anchor residues for binding to HLA A11 and A3 were identified at position 2 (isoleucine) and at position 9 (histidine) or at position 8 (arginine) of the epitope sequence. The identification of overlapping CD4+ and CD8+ T-cell epitopes within the capsid protein sequence C(263-275) implicates a strategy for using such epitopes in a candidate peptide-based rubella vaccine.

Randomised double-blind placebo-controlled study on adverse effects of rubella immunisation in seronegative women

BACKGROUND

The objective of our study was to investigate the association of adverse clinical musculoskeletal and neurological events in healthy postpartum women with live attenuated (RA27/3 strain) rubella-virus vaccine, and to assess the frequency of acute and recurrent arthralgia and arthritis and associations with acute and recurrent muscle pain (myalgia) and neurological manifestations (paraesthesias).

METHODS

We used a randomised placebo-controlled, double-blind design in a community setting. 636 women were enrolled and, after 90 women dropped out, 546 healthy women aged 18-41 years, who were rubella seronegative on routine screening were immunised parenterally with either monovalent live attenuated (RA27/3 strain) rubella vaccine (n = 270) or saline placebo (n = 276) in the postpartum period. Outcome measures were the occurrence of acute and persistent or recurrent joint manifestations (arthralgia or arthritis) at 1, 3, 6, 9, and 12 months after immunisation. Occurrence of muscle pain (myalgia), and neurological symptoms (paraesthesia) was also assessed at the same times.

FINDINGS

543 women completed 1-month follow-up. 456 women completed the 12-month assessment. There were no differences at the time of immunisation between rubella vaccine and placebo groups in distribution of age, ethnic origin, parity, time between delivery and immunisation, breastfeeding history, or histories of earlier rubella vaccination or joint complaints. Results indicated a significantly higher incidence (p = 0.006; odds ratio = 1.73 [95% CI = 1.17-2.57]) of acute joint manifestations in rubella-vaccine recipients (30%) than in placebo recipients (20%). Frequency of chronic (recurrent) arthralgia or arthritis was only marginally significant (p = 0.042; 1.58 [1.01-2.45]).

INTERPRETATION

RA27/3 rubella vaccine given to seronegative women during the postpartum period was significantly associated with development of acute arthralgia or arthritis. Although the numbers of women assessed and length of follow-up revealed only marginally significant differences in persistent or recurrent joint manifestations between rubella vaccine and placebo recipients, it is possible that susceptible women who are given rubella vaccination may experience this outcome.

Recognition of contiguous allele-specific peptide elements in the rubella virus E1 envelope protein

Peptides which bind to human HLA-DRB1 class II molecules in an allele-specific fashion were derived from the immunodominant E1 envelope protein of rubella virus. Two nonoverlapping E1 peptide epitopes were recognized by rubella virus-specific T cells in the context of independent HLA alleles when presented either separately or as a contiguous polypeptide containing both epitopes. Direct binding analysis of potential peptide epitopes to distinct HLA molecules provides a direct approach for selecting antigenic peptides useful for epitope-based vaccine targeted to multiple HLA types.

HLA-DR restrictive supertypes dominate promiscuous T cell recognition: association of multiple HLA-DR molecules with susceptibility to autoimmune diseases

The association of individual autoimmune diseases with multiple HLA molecules has remained an enigma. That T cells can recognize the same peptide presented by several different HLA-DR alleles (i.e., promiscuous recognition) has been well documented. To explain this, we propose the "DR restrictive supertype pattern (DR RSP)" hypothesis. We focus on the known amino acid polymorphisms at positions beta 70, beta 71, and beta 74 located within pocket 4 of the DR molecule and their potential influence on promiscuous T cell recognition. We have shown that HLA-DR alleles may be grouped, on the basis of their polymorphisms at these positions, into at least 6 sets of DR alleles, 4 of which share, respectively, one of the RSP: A (Q/RR/KA), D (DE/R[K]A/L), E (Q/RRE), or R (QKR/Q) and 2 of which share the restrictive patterns Q (DRQ) or a (QAA). Most of the RSP have been shown to be associated with promiscuous T cell recognition of antigenic peptides. We also provide a rationale on how different DR alleles, exhibiting a particular RSP, might be capable of binding an antigenic peptide and presenting it, in a promiscuous fashion, to peptide-specific T cells. By identifying these RSP represented by DR alleles that have been clinically associated with certain autoimmune disease, we also extend the DR RSP hypothesis to account for the association of certain autoimmune diseases with multiple HLA-DR alleles.

New, ultrasensitive enzyme immunoassay for detecting vaccine- and disease-induced hepatitis A virus-specific immunoglobulin G in saliva

Although detection of disease-induced hepatitis A virus (HAV)-specific antibodies in saliva has been successfully utilized in a few epidemiological studies, available assays fail to detect lower salivary anti-HAV levels associated with vaccine-induced immunity. We present a new capture enzyme immunoassay which employs a three-layer antibody recognition system. Evaluation of paired saliva-serum specimens from 1,025 international travellers, 134 other volunteers, and 91 hepatitis A vaccine recipients demonstrated 99.6% (95% confidence interval, 98.4 to 99.9) specificity and 98.7% (95% confidence interval, 97.7 to 99.4) sensitivity of this salivary assay in differentiating between immune and susceptible individuals, compared with serum-based methods. We conclude that this assay is sufficiently sensitive for reliable detection of both vaccine- and infection-induced HAV-specific immunoglobulin G in saliva, even when corresponding anti-HAV levels in serum are very low (< 1 IU/ml).

Characterization of the HLA-restrictive elements of a rubella virus-specific cytotoxic T cell clone: influence of HLA-DR4 beta chain residue 74 polymorphism on antigenic peptide-T cell interaction

The influence of glutamic acid (E)-alanine (A) dimorphism at position 74 of the DR4 beta chain on cytotoxic T cell recognition of an antigenic rubella virus peptide, E1(273-284), was studied using a panel of B cell lines and B cell transfectants expressing different HLA-DRB1 alleles as antigen-presenting cells and targets in 51Cr-release assays. Only B cell lines expressing the DRB1*0403, DRB1*0406 or DRB1*0407 subtypes which shared a residue, E, at position 74 in the DR4 beta chain when sensitized with E1(273-284) elicited strong cytotoxic T lymphocyte responses. However, in direct binding and antibody inhibition assays, it was shown that biotinylated E1(272-285) could bind to DR molecules with residues other than E at position 74, including DRB1*0401, DRB1*0404 and DRB1*1101 expressed on transfectants. E1(272-285) bound with similar affinity to the transfectant with DRB1*0403, which has E at position 74, as well as the transfectant with DRB1*0404, which does not. When T-B cell engagement rates were compared in cell conjugate assays, the percentage of T-B conjugates was higher when peptide-pulsed transfectants with DRB1*0403 were used than with transfectants expressing DRB1*0404. Hence, the HLA DR beta 1 polymorphism at position 74, while not critical for the binding affinity of E1(272-285) to the HLA molecule, appears to be a primary determinant of restricted recognition and subsequent activation of the peptide-specific T cells.

Rubella reimmunization: comparative analysis of the immunoglobulin G response to rubella virus vaccine in previously seronegative and seropositive individuals

Rubella virus (RV)-specific immunoglobulin G (IgG) antibodies were studied in military recruits undergoing unselected immunization with live attenuated measles, mumps, and rubella virus (MMR) vaccine. Three different whole-RV enzyme immunoassays (EIAs) and an epitope-specific EIA with a synthetic peptide (BCH-178c) representing a heutralization domain on the RV E1 envelope protein were used. Before vaccination, 84.2, 87.7, and 84.5% of the subjects tested (n = 399) were found to be seropositive (> 10 IU/ml or assay equivalent) by the three whole-RV EIAs, respectively, while only 82.5% were seropositive by the BCH-178c EIA. Although prevaccination seropositivity rates were similar for the whole-RV EIAs (sensitivity, 94 to 100%), many sera considered seropositive by the whole-RV EIAs had E1 peptide EIA antibody levels of < 10 IU/ml (sensitivity, 77.4 to 80.7%). One month after vaccination, 97.8, 97.2, and 93.5% of the subjects who were followed (n = 356) were seropositive by the three whole-RV EIAs, respectively, while 89% had BCH-178c peptide-specific IgG titers of > 10 IU/ml. After vaccination, depending on the assay used, up to 20.6% of initially seropositive individuals exhibited a greater than fourfold increase in RV-specific IgG, while up to 47.3% showed a greater than twofold increase. Increased antibody titers after vaccination (seroboosting) were most frequently associated with low levels of BCH-178c peptide-specific IgG before vaccination. RV protein-specific IgG was also studied by immunoblot assays in a subset (n = 56) of individuals receiving the MMR vaccine. Of these, 89.4 and 91.1% exhibited RV protein (E1, E2, and C protein)-specific IgG before and after vaccination, respectively. Seroboosting (two- to fourfold increase in EIA titers of individuals seropositive by the whole-RV EIA before vaccination) was usually accompanied by a shift in the IgG immunoblot pattern from a single (E1) to multiple (E1-E1, E1-C, or E1-E2-C) specificities, suggesting exposure of new epitopes as a result of viral replication.

Recognition of altered self major histocompatibility complex molecules modulated by specific peptide interactions

Antigen-specific and major histocompatibility complex (MHC)-restricted recognition by the T cell receptor involves multiple structural contacts over a large molecular surface area. Using a human T cell clone specific for a rubella viral peptide restricted by subsets of HLA DR4 molecules, we identified structurally diverse combinations of peptide-MHC complexes which were functionally equivalent to T cell recognition. Presentation of the rubella-derived peptide on DR4 molecules with an E-74 polymorphism triggered T cell recognition, as did presentation of a single amino acid-substituted peptide in the context of DR4 molecule which lacked the E-74 site. Peptide binding and molecular modeling analysis indicates the structural and functional complementarity of T cell recognition for a specific amino acid side chain, whether contributed by the peptide or by the MHC molecule.

Analysis of meningococcal serogroup C-specific antibody levels in British Columbian children and adolescents

The effects of age, sex, and possible prior exposure to serogroup C meningococci on group C-specific antibody levels (total and functional) were examined in 2- to 19-year-olds just before and 1 and 12 months after immunization with divalent (groups A + C) meningococcal capsular polysaccharide vaccine. Only age was found to have a significant effect on antibody levels. At 1 month, only 50% of 2- to 6-year-olds had detectable serum bactericidal antibody, in contrast to 84.1% and 96.3% of 9- to 12- and 13- to 19-year-olds respectively. By 12 months, only 20%, 40.9%, and 53.8% of subjects in these age groups had serum bactericidal antibody, suggesting that current meningococcal C polysaccharide vaccines provide only short-term protection. However, the drop in total specific antibody levels (by EIA) was less pronounced. Persistence of antibodies detectable by EIA (but not serum bactericidal antibodies) suggests that this vaccine may also give rise to antibodies of low affinity or directed to nonfunctional (nonprotective) epitopes (or both).

Lipomatous meningioma: characteristic computed tomographic appearance

A case of lipomatous meningioma is reported. This is a rare variant of meningioma in which metaplasia of meningoepithelial cells occurs and mature adipocytes are present within the tumour. The heterogeneous attenuation and heterogeneous enhancement visualized on computed tomography (CT) can mimic necrotic malignant tumours. However, the demonstration of fat attenuation within the tumour explains the heterogeneity and suggests a benign process. The differential diagnosis of an extra-axial fat-containing tumour should include lipomatous meningioma.

Predicting total weight of retail-ready lamb cuts from bioelectrical impedance measurements taken at the processing plant

Data of sixty finished, crossbred lambs were used to develop prediction equations of total weight of retail-ready cuts (SUM). These cuts were the leg, sirloin, loin, rack, shoulder, neck, riblets, shank, and lean trim (85/15). Measurements were taken on live lambs and on both hot and cold carcasses. A four-terminal bioelectrical impedance analyzer (BIA) was used to measure resistance (Rs, ohms) and reactance (Xc, ohms). Distances between detector terminals (L, centimeters) were recorded. Carcass temperatures (T, degrees C) at time of BIA readings were also recorded. The equation predicting SUM from cold carcass measurements (n = 53, R2 = .97) was .093 + .621 x weight-.0219 x Rs + .0248 x Xc + .182 x L-.338 x T. Resistance accounted for variability in SUM over and above weight and L (P = .0016). The above equation was used to rank cold carcasses in descending order of predicted SUM. An analogous ranking was obtained from a prediction equation that used weight only (R2 = .88). These rankings were divided into five categories: top 25%, middle 50%, bottom 25%, top 50%, and bottom 50%. Within-category differences in average fat cover, yield grade, and SUM as a percentage of cold carcass weight of carcasses not placed in the same category by both prediction equations were quantified with independent t-tests. These differences were statistically significant for all categories except middle 50%. This shows that BIA located those lambs that could more efficiently contribute to SUM because a higher portion of their weight was lean.

Use of synthetic peptides to map regions of rubella virus capsid protein recognized by human T lymphocytes

Synthetic peptides (SPs), 18-29 amino acids long, representing selected sequences of rubella virus (RV) capsid (C) protein were used in lymphocyte proliferation assays to identify antigenic regions recognized by T lymphocytes from healthy RV-reactive adults. Four SPs, C(1-29), C(90-114), C(108-134) and C(255-300), stimulated proliferation of peripheral blood mononuclear cells and RV-specific T-cell lines from the same donors. C(1-29V), an SP analogue containing an RA27/3 RV vaccine strain sequence, stimulated higher levels of proliferation in T cells obtained from RV-vaccinated subjects than did the comparable wild-type (M33 strain) RV sequence.

Analysis of overlapping T- and B-cell antigenic sites on rubella virus E1 envelope protein. Influence of HLA-DR4 polymorphism on T-cell clonal recognition

A CTL antigenic site located between residues 273 and 291 of the E1 envelope protein of RV was identified by 51Cr-release assays employing SPs. Two E1-specific CTL clones were examined for immune recognition of RV wild-type and attenuated vaccine strains and recombinant E1 protein. The exact sequence (273-284) recognized by both clones was delineated by using truncated and overlapping SPs covering these residues. The defined T-cell site overlapped almost completely with a virus neutralizing antibody-binding site previously identified with mouse monoclonal and human antibodies. A series of single aa-substituted SP analogues of E1(273-284) was used to define residues critical for T-cell recognition. Using EBV-BL displaying different HLA-DR haplotypes and -DR4 subtypes as targets to determine MHC class II restriction elements, immune recognition by both T-cell clones was shown to be associated with HLA-DR4. Three HLA-DR4 subtypes (DR4Dw13A, DR4Dw13B, and DR4KT2) sharing a common residue, glutamic acid at position 74 in their beta 1 chains, were able to present SP E1(273-284) to the T-cell clones.

A simple simulation for the visualisation of CSF flow in infants with hydrocephalus

Cerebrospinal fluid (CSF) flow was demonstrated incidentally in our unit during the routine cranial colour Doppler examination of infants with hydrocephalus. Pulsed Doppler analysis of the flow jets within CSF has shown that for each CSF flow jet there is a characteristic sinusoidal wave pattern that decreases in amplitude at the end of each jet episode. Any activity that transiently elevates the intracranial pressure, such as crying, increased the intensity of this signal. A study was subsequently carried out to investigate the origin of these clinical observations of CSF flow. Using a simple flow phantom, experiments with degassed water demonstrated the transient production of a Doppler signal at a stenosis in an otherwise uniform bore tube. We postulate that in infants with obstructive hydrocephalus, high CSF velocities in excess of 25 cm/s are produced as a result of the pressure caused by the excess cerebrospinal fluid. In some instances fluid jets may give rise to the production of microbubbles that act as transient but extremely efficient reflectors for the ultrasound, thus enabling the visualisation of CSF flow in these patients.