Collision tumour of the oesophagus: a challenge for histological diagnosis.

An unusual case of mantle cell lymphoma metastasising to squamous cell carcinoma of the oesophagus, in a 62 year old Chinese man, is reported. A histological diagnosis based on examination of a small endoscopic biopsy specimen, in the absence of detailed clinical information, may be difficult, as the lymphoma component can be mistaken for reactive lymphoid infiltrate which is sometimes present adjacent to squamous cell carcinoma. Correlation with the clinical history, careful assessment of the subtle histological changes, and use of ancillary methods such as immunohistochemistry are most helpful in making the correct diagnosis. This case also illustrates further the possible occurrence of lymphomatous infiltrates surrounding other lesions in patients with a previous or concurrent history of lymphoma.     

"Waste" follicular aspirate from fertility treatment--a potential source of human germline stem cells?

Fertility clinics worldwide routinely produce a large volume of 'waste' follicular aspirate, which is potentially an abundant source of immature ovarian follicles. Current attempts to cultivate these further in vitro to yield viable mature oocytes for fertility treatment have not yet achieved much success. Instead, recent lines of evidence have emerged that are suggestive of a potential stem cell niche within such immature ovarian follicles. The recent discovery of follicular renewal and putative germ-line stem cells within the postnatal mammalian ovary shook the foundations of reproductive biology by challenging the established dogma that mammalian females lose the capacity for germ cell renewal during fetal life, such that a fixed reserve of germ cells (oocytes) enclosed within follicles is endowed at birth. More intriguingly, another recent study in the Drosophila model provided compelling evidence that somatic progenies (nurse cells) of germ-line stem cells had the ability to revert back to the stem-cell-like state. This introduces the exciting possibility that within the mammalian ovarian follicle, similar somatic progenies of germ-line stem cells may also possess a greater intrinsic ability to revert back into functional stem cells. If this is the case, then a favored candidate would be the cumulus/granulosa of immature ovarian follicles, since such cells are true homologues of nurse cells found within the Drosophila ovary. The successful elucidation of a human germ-line stem cell niche within immature ovarian follicles is likely to have huge ramifications in stem cell biology and regenerative medicine.     

Neural progenitor cells lack immunogenicity and resist destruction as allografts

Multipotent, self-renewing stem and progenitor cells isolated from the mammalian central nervous system (CNS) have been shown to survive as allografts following transplantation to sites throughout the neuraxis. However, studies of this type shed little light upon the immunologic properties of the cells themselves, primarily because little is learned about the intrinsic immunogenic properties of a cell when it is grafted into an immune-privileged site. We have therefore investigated the immunogenic and antigenic properties of CNS progenitor cells by grafting them into a conventional (i.e., non-immune-privileged) site, namely, beneath the kidney capsule. Our results indicate that allogeneic CNS progenitor cells survive at least 4 weeks in a conventional site, during which time they neither sensitize their hosts nor express detectable levels of major histocompatibility complex (MHC) class I or II. These in vivo data are in accord with flow cytometric results showing that CNS progenitor cells do not express MHC class I or class II, either at baseline or upon differentiation in 10% serum. Exposure to interferon gamma, however, reversibly upregulates expression of these key transplantation antigens. Together, these results reveal CNS progenitor cells to possess inherent immune privilege. Since CNS progenitor cell allografts were rejected beneath the kidney capsule following specific sensitization of the host, CNS progenitor cells were able to display alloantigens, albeit not in an immunogenic form.     

The rise and fall of i-STAT point-of-care blood gas testing in an acute care hospital

In response to a $350,000 laboratory budget cut and closure of an intensive care unit-based laboratory and a desire to maintain turnaround times of 10 minutes or less, a multidisciplinary group developed and implemented point-of-care (POC) testing. Only blood gases (pH, PO2, and PCO2) and ionized calcium values were deemed essential stat tests. Three commercially available POC blood gas devices were evaluated; all yielded results comparable to in-house reference methods. The 1 device with a US Food and Drug Administration-approved method for ionized calcium testing and with an existing interface for laboratory information systems was selected. Fiscal analysis predicted annual savings of approximately $225,000. POC blood gas analysis was implemented in April 1996 coincident with closure of the intensive care unit-based laboratory. Clinical laboratories and POC blood gas test volumes remained constant through August 1998; in contrast, the number of ionized calcium tests decreased dramatically after April 1996. In August 1998, clinically significant (i.e., artificial ventilation parameters would have been altered based on test results) discrepant PCO2 values were observed sporadically and noted only with patient specimens, not with commercial controls or electronic simulators. Because investigation failed to identify the cause, use of the POC device was discontinued in September 1998.     

Micro-centrifugation of human spermatozoa: its effect on fertilization of hamster oocytes after micro-insemination spermatozoal transfer

Micro-centrifugation (MC) at 6500 r.p.m. (3352 g) has not beenused previously for spermatozoal concentration and subsequentfertilization. We investigated MC for micro-insemination spermatozoaltransfer (MIST) of human spermatozoa from normal donors intohamster oocytes. MC resulted in reduced penetration of hamsteroocytes, both after MIST [77.4% (41/53) versus 87.8% (43/49)for control; NS] and after exposure to zona-free hamster oocytes[60.8% (79/130) versus 72.7% (88/121) for control; P < 0.05].However, MIST under the zona resulted in better incorporationof sperm nuclei when compared with zona-free hamster oocytes,for spermatozoa exposed to micro-centrifugation (77.4 versus60.8%, P < 0.05) and controls (87.8 versus 72.7%, P <0.05). Polyspermy was higher after MIST [22.0% (9/41) versus13.9% (11/79); NS] for MC + , and [25.6% (11/43) versus 13.6%(12/88); NS] for MC-. We conclude that MC does have a negative,but minimal effect on the fertility of human spermatozoa withrespect to hamster oocytes.     

Seven new HLA-B alleles associated with antigens in the B7 CREG

This paper describes seven novel HLA-B alleles. Five of these new alleles contain polymorphic motifs previously reported in HLA-B alleles, suggesting an origin resultant from a gene conversion mechanism. B*0723 contains a polymorphism previously unreported in class I HLA molecules. B*4105 contains a nucleotide substitution previously unreported in class I HLA molecules, which encodes a protein sequence previously reported only in HLA-C locus alleles.     

Role of antigen density in immune lysis of interferon-treated human lymphoid cells: analysis with monoclonal antibodies to the HLA-A,B antigenic molecular complex and to Ia-like antigens

Cultured human lymphoid WI-L2 cells incubated with human leucocyte interferon (final concentration 500 and 2000 U/ml) for 16 h at 37 degrees C acquire increased susceptibility to complement and cell-dependent lysis mediated by monoclonal antibodies to HLA-A,B antigens and to human beta 2-microglobulin but do not change in their susceptibility to immune lysis mediated by monoclonal antibodies to human Ia-like antigens. Changes in susceptibility to immune lysis of interferon-treated lymphoid cells are likely to reflect changes in antigen density, since binding assays with monoclonal antibodies and quantitative absorption assays with alloantisera have shown that the expression of HLA-A,B antigens and beta 2-microglobulin is significantly increased on interferon-treated lymphoid cells, whereas that of Ia-like antigens in not changed.