Mucosal immunization with PLGA-microencapsulated DNA primes a SIV-specific CTL response revealed by boosting with cognate recombinant modified vaccinia virus Ankara

Systemically administered DNA encoding a recombinant human immunodeficiency virus (HIV) derived immunogen effectively primes a cytotoxic T lymphocyte (CTL) response in macaques. In this further pilot study we have evaluated mucosal delivery of DNA as an alternative priming strategy. Plasmid DNA, pTH.HW, encoding a multi-CTL epitope gene, was incorporated into poly(D,L-lactic-co-glycolic acid) microparticles of less than 10 microm in diameter. Five intrarectal immunizations failed to stimulate a circulating vaccine-specific CTL response in 2 Mamu-A*01(+) rhesus macaques. However, 1 week after intradermal immunization with a cognate modified vaccinia virus Ankara vaccine MVA.HW, CTL responses were detected in both animals that persisted until analysis postmortem, 12 weeks after the final boost. In contrast, a weaker and less durable response was seen in an animal vaccinated with the MVA construct alone. Analysis of lymphoid tissues revealed a disseminated CTL response in peripheral and regional lymph nodes but not the spleen of both mucosally primed animals.     

Extramedullary myeloid cell tumours localised to the mediastinum: a rare clinicopathological entity with unique karyotypic features

Extramedullary myeloid cell tumour (EMMT) localised to the mediastinum is a rare manifestation of acute myeloid leukaemia, forming less than 4% of all cases of EMMT. In contrast to other types of EMMT, cytogenetic characteristics of this rare entity are relatively unknown. This report describes a patient with EMMT who had evidence of superior vena cava syndrome and normal peripheral blood counts at diagnosis. The results from an initial biopsy specimen were consistent with a diagnosis of mediastinal large B cell lymphoma. A diagnosis of acute myeloid leukaemia was made three months after initial diagnosis by bone marrow examination. Review of the initial biopsy specimen showed strong positivity for myeloperoxidase, revealing that the patient had been initially misdiagnosed as having large B cell lymphoma. Cytogenetic studies revealed a near triploid and near tetraploid karyotype with structural abnormalities in 12 and three metaphases, respectively. Review of the literature showed that a near tetraploid or triploid karyotype is found in most of the reported cases of mediastinal EMMT. Thus, the presence of a near triploid/tetraploid karyotype and mediastinal EMMT may represent a specific subset of EMMT. The biological relevance of this observation is discussed.     

Ultimate tensile strength of dentin: Evidence for a damage mechanics approach to dentin failure

Dentin structure and properties are known to vary with orientation and location. The present study explored the variation in the ultimate tensile strength (UTS) of dentin with location in the tooth. Hourglass specimens were prepared from dentin located in the center, under cusps, and in the cervical regions of human molar teeth. These were tested in tension at various distances from the pulp. Median tensile strengths ranged from 44.4 MPa in the inner dentin near the pulp, to 97.8 MPa near the dentino-enamel junction (DEJ). This increase in the median UTS with distance from the pulp to the DEJ was statistically significant (P <.001). Of particular importance was the observation that the UTS measurements followed a Weibull probability distribution, with a Weibull modulus of about 4.5. The Weibull behavior of the UTS data strongly suggests that the large variances in fracture strength data result from a distribution of preexisting defects in the dentin. These findings justify a damage-mechanics approach to studies of dentin failure.     

The Schizosaccharomyces pomberfc3 + gene encodes a homologue of the human hRFC36 and Saccharomyces cerevisiae Rfc3 subunits of replication factor C

In the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe replication factor C (RF-C) plays key roles both in chromosomal DNA replication and in DNA replication checkpoint function. At the replication fork, the five-subunit RF-C complex functions to load the trimeric polymerase accessory factor PCNA onto DNA. PCNA then acts as a sliding clamp, tethering Pol δ to the DNA to maximise its processivity. Here we describe the cloning of the S. pomberfc3 ⁺ gene, encoding a homologue of the S. cerevisiae Rfc3 and human hRFC36 proteins. The 1026 bp rfc3 ⁺ ORF is interrupted by five introns, ranging in size from 49 to 165 bp. The spliced ORF is predicted to encode a 342 amino-acid protein that is approximately 50% identical at the amino acid sequence level to the S. cerevisiae Rfc3 and human hRFC36 proteins. As expected, S. pomberfc3 ⁺ is an essential gene, with rfc3Δ cells being defective for DNA replication. Loss of rfc3 ⁺ function can be rescued by heterologous expression of either the S. cerevisiae Rfc3 or human hRFC36 proteins in S. pombe. Received: 15 October 1999     

Recognition surfaces of MHC class I

Summary: Recent crystallographic results have provided dose to atomic resolution views of the recognition events mediated by MHC class I molecules. The specificity-conferring interaction of MHC class I/peptide with a T-cell antigen receptor (TCR) appears dependent on certain key interactions with the MHC scaffold. These interactions, in particular those of the TCR Va domain, define a standard orientation for TCR binding. Previous studies on biologically significant variations in the TCR recognition surface presented by a series of MHC/variant peptide complexes can be reassessed in the light of this TCR-building mode. The interaction of CDS with MHC class I resembles that between antibody and antigen in the use of loops from the CD8 structure. The interaction is of very low affinity and buries equivalent surface area to that between the TCR and MHC class I but while the TCR/MHC interface shows poor surface shape complementarity the match in the conservative interaction between MHC and CDS is precise.     

Total ovarian volume before human chorionic gonadotrophin administration for ovulation induction may predict the hyperstimulation syndrome

Total ovarian volumes were measured before the administrationof HCG in 42 women undergoing treatment for infertility by in-vitrofertilization (IVF) and embryo transfer and considered to havean exaggerated response to stimulation (>20 follicles). Sevenwomen who subsequently developed moderate or severe ovarianhyperstimulation syndrome (OHSS) (n = 7; group 1) were comparedwith 35 matched controls (five matched controls per case; n= 35; group 2) of similar age, number of follicles and durationof infertility who underwent follicular stimulation, oocyterecovery, in-vitro fertilization and embryo transfer duringthe same period but did not develop moderate or severe OHSS.The mean age, duration of infertility and total number of follicleswere similar but the mean total ovarian volume was significantlyhigher in the group of women who developed moderate or severeOHSS compared with controls (271.00 ± 87.00 versus 157.30± 54.20 ml; P < 0.01). We conclude that total ovarianvolume measured before HCG administration is higher in womenwho develop moderate or severe OHSS compared with controls andmay therefore be used as an additional parameter in the preventativestrategy for the ovarian hyperstimulation syndrome.     

Neural projections of the preoptic-suprachiasmatic region to the median eminence in the rat: A quantitative autoradiographic study

The possibility of a preferential distribution of projections from the preoptic-suprachiasmatic region (POA-Sch) to the median eminence in the male rat was studied using autoradiographic and computer procedures. A cocktail of [3H]leucine-[3H]proline was injected into the POA-Sch. Animals were killed after either 1, 4, or 24 h of incorporation time (IT). The number of silver grains per 25-micron square was counted throughout the median eminence. Squares with silver grain densities at or above the 75 percentile of the population for any given IT group were labeled as "concentrating areas." The distribution of these concentrating areas in median eminence tissue was analyzed utilizing univariate procedures. Visual inspection of the distribution of silver grain densities in a rostrocaudal fashion indicated the likelihood of uneven distribution; however, these differences were not statistically significant. In the dorsoventral plane, results indicated that the highest silver grain density was at 50 to 75 micron from the floor of the 3rd ventricle. Such distribution was apparent both ipsi- and contralateral to the injection site, but was greater on the ipsilateral side.     

Human multilineage progenitor cell sensitivity to 4-hydroperoxycyclophosphamide

This institution has documented consistent reconstitution of hematopoiesis in patients treated with marrow lethal chemoradiotherapy who are "rescued" by reinfusion of autologous cryopreserved marrow cells incubated with 4-hydroperoxycyclophosphamide (4-HC) for in vitro purging of occult tumor cells. After 4-HC incubation, the reinfusion marrow cells showed marked reduction in committed progenitor cell (BFU-E, CFU-GM) frequency, and often total absence of detectable progenitors, without significant loss of marrow reconstituting ability. Since BFU-E and CFU-GM assays did not predict marrow reconstituting ability after 4-HC incubation, we sought to determine whether multilineage progenitor cells (CFU-GEMM) might be more resistant to 4-HC incubation and therefore a more reliable predictive assay in this setting. We found that BFU-E, CFU-GM, and CFU-GEMM all show similar dose-related sensitivity to in vitro incubation with 4-HC and do not appear representative of the cell(s) responsible for marrow reconstitution.