Various factors are known to regulate cell growth and differentiation, but less is known of agents which affect movement and positioning, particularly in epithelial-mesenchymal interactions. Cultured human embryo fibroblasts release a protein with a relative molecular mass (Mr) of approximately 50,000 (50K) that affects epithelial cells by causing a disruption of junctions, an increase in local motility and a scattering of contiguous sheets of cells. To investigate specificity, a range of cells has been examined for the ability to produce the factor and for sensitivity to its action. Most freshly isolated normal epithelia and epithelia from cell lines of normal tissue, but not epithelia from tumour cell lines or fibroblasts, were sensitive to scatter factor. In contrast, production of the factor, as identified by activity and by chromatography, was restricted to embryonic fibroblasts and certain variants of 3T3 and BHK21 cells and their transformed derivatives. We conclude that the scatter factor is a paracrine effector of epithelial-mesenchymal interaction, which affects the intercellular connections and mobility of normal epithelial cells. The factor might be involved in epithelial migration, such as occurs in embryogenesis or wound healing.

The population prevalence of multiple sclerosis is 0.1%; however, the risk of the disease in the siblings of affected individuals is very much higher at 3-5%. The importance of genetic factors in accounting for this increased risk is confirmed by the results of twin and adoption studies. Despite the evidence for a strong genetic effect, a weak major histocompatibility complex (MHC) association is the only consistently observed feature in the genetics of multiple sclerosis. Other candidates have been proposed, including genes encoding the immunoglobulin heavy chain, T cell receptor beta chain and APOC2, but none has yet been confirmed. Evidence for linkage and association to the myelin basic protein gene has been reported in a genetically isolated Finnish population, but it has not been possible to reproduce these results in other populations. We used a two-stage approach to search the human genome for the genes causing susceptibility to multiple sclerosis. Two principal regions of linkage are identified, chromosomes 17q22 and 6p21 (MHC). Our results are compatible with genetic models involving epistatic interaction between these and several additional genes.

Scatter factor is a fibroblast-derived protein that causes separation of contiguous epithelial cells and increased local mobility of unanchored cells. Highly purified scatter factor has been obtained by a combination of ionexchange and reverse-phase chromatography from serum-free medium conditioned by a ras-transformed clone (D4) of mouse NIH 3T3 fibroblasts. Under nonreducing conditions scatter factor has a pI of -9.5 and migrates in SDS/polyacrylamide gels as a single band at -62 kDa from which epithelial scatter activity can be recovered. Treatment with reducing agents destroys biological activity and is associated with the appearance of two major bands at "57 and "30 kDa. Whether both the 57-kDa and 30-kDa polypeptides are required for biological activity remains to be established. All the activities observed in crude medium conditioned by cells producing scatter factor are retained by highly purified preparations of scatter factor.These include (i) increased local movement, modulation of morphology, and inhibition of junction formation by single epithelial cells and (it) disruption of epithelial interactions and cell scattering from preformed epithelial sheets. These changes occur with picomolar concentrations of purified scatter factor and without an effect on cell growth.Cell movement is restricted by the interaction with basement and extracellular membrane proteins (1) and, in certain tissues, by cell-cell interactions that involve cell-specific adhesion molecules (2). Movement of epithelial cells is further limited by cell-cell (desmosomes, tight and gap junctions) and cell-substratum (hemidesmosomes) junctional systems. Cytokines are also involved in the regulation of cell movement, as it appears that certain growth factors, including nerve growth factor (3), platelet-derived growth factor (4), and epidermal growth factor (5, 6) may stimulate cell movement as well as cell growth.There is increasing evidence, however, for a new group of cytokines that regulate cell movement with little or no effect on cell growth. Pioneering studies by Yoshida et al. (7) indicated that certain mouse and rat hepatoma lines and mouse and human leukemias produced a protein of 70 kDa that was chemotactic for the producer cells as well as for other tumor cells but not for polymorphonuclear cells (7). More recently, another motility factor has been isolated from serum-free medium conditioned by the human melanoma line A2058. This 55-kDa protein has both chemotactic and chemokinetic activity for the producer cells (but not for polymorphonuclear cells) and has been designated autocrine motility factor (AMF) (8). ras-transformed derivatives of mouse NIH 3T3 fibroblasts also produce AMF and respond to it and, interestingly, normal NIH 3T3 firboblasts, which do not produce AMF, are able to respond to the AMF secreted by ras-tranformed cells (8). A factor similar to AMF has been isolated from serum-free medium conditioned by a highly metastatic clone (MTLn3) of rat mammary adenocarcinoma (9). This factor (53 kDa) is chemota...

Genetic susceptibility to multiple sclerosis is implicated on the basis of classical family studies and phenotype analyses. The only reproducible legacy from the candidate gene approach has been the discovery of population associations with alleles of the major histocompatibility complex. Systematic genome scanning has since been applied using a panel of anonymous markers to identify areas of linkage in co-affected siblings. Here, we describe the principles of genome screening and update the UK survey of multiple sclerosis. This identified 20 regions of potential interest, but in none was there unequivocal linkage. In theory, attempting to replicate these findings in a second set of sibling pair families is the most appropriate way to distinguish true from false positives, but unfortunately the number of families required to do this reliably is prohibitively large. We used three approaches to increase the definition achieved by the screen: (i) the number of sibling pairs typed in an identified region of potential linkage was extended; (ii) the information extraction was increased in an identified region; and (iii) a search was made for missed regions of potential linkage. Each of these approaches has considerable limitations. A chromosome-by-chromosome account is given to direct future searches. Although an additional marker placed distal to the 'hit' on chromosome 14q increased linkage in this area, and typing extra sibling pairs increased linkage on chromosomes 6p and 17q, evidence for linkage was more commonly reduced and no additional regions of interest were found. A further refinement of the genome screen was undertaken by conditioning for the presence of HLA-DR15. This produced a surprising degree of segregation among the regions of interest, which divided into two distinct groups depending on DR15 sharing: the DR15-sharing cohort comprised loci on chromosomal areas 1p, 17q and X; and the DR15-non-sharing cohort was made up of loci on 1cen, 3p, 7p, 14q and 22q. This result further highlights the genetic complexity of multiple sclerosis. What can now be inferred is that a gene of major effect is excluded from 95% of the genome and one with a moderate role from 65%, whereas genes which make a very small biological contribution cannot be discounted from any region. The available results suggest that multiple sclerosis depends on independent or epistatic effects of several genes each with small individual effects, rather than a very few genes of major biological importance.

SUMMARY Of the first 250 heart and 35 heart and lung transplant recipients at Papworth Hospital, Cambridge, who survived for more than one month after transplantation, 217 heart and 33 heart and lung patients were investigated serologically for evidence of Toxoplasma gondii infection. Six patients acquired primary Tgondii infection, most probably from the donor organ. Five patients experienced Tgondii recrudescence, two of whom had recovered from primary infection a few years earlier. Two patients died from primary Tgondii infection and the severity of symptoms in the other patients with primary infection was related to the amount of immunosuppressive treatment. Prophylaxis with pyrimethamine (25 mg a day for six weeks) was introduced for Tgondii antibody negative transplant recipients who received a heart from a T gondii antibody positive donor after the first four cases of primary toxoplasmosis. Ofthe seven patients not given pyrimethamine, four (57%) acquired primary Tgondii infection. This compared with two of the 14 patients (14%) given prophylaxis.

Linkage analysis in multiplex families has provisionally identified several genomic regions where genes influencing susceptibility to multiple sclerosis are likely to be located. It is anticipated that association mapping will provide a higher degree of resolution, but this more powerful approach is limited by the substantial genotyping effort required. Here, we describe the first use of DNA pooling to screen the whole genome for association in multiple sclerosis based on a 0.5 cM map of microsatellite markers and using four DNA pools derived from cases (n = 216), controls (n = 219) and trio families (n = 745 affected individuals and their 1490 parents). The 10 markers showing the greatest evidence for association with multiple sclerosis that emerge from this analysis include three from the HLA region on chromosome 6p (D6S1615, D6S2444 and TNFa), providing a positive control for the method, four from regions previously identified by linkage analysis in UK multiplex families (two mapping to chromosome 17q GCT6E11 and D17S1535; one to chromosome 1p GGAA30B06; and one to 19q D19S585), and three from novel sites with respect to linkage analysis (D1S1590 at 1q; D2S2739 at 2p; and D4S416 at 4q). Our results thus provide further supporting evidence for the candidature of 6p, 17q, 19q and 1p as regions encoding susceptibililty genes for multiple sclerosis. The protocol used in this UK-based study is now being extended to 18 additional sites in Europe in order to search for susceptibility genes shared between populations of common ancestry, as well as those that exert ethnically more restricted effects.

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Aims-To determine the accuracy of eight commercially available kits for the serological diagnosis of Helicobacterpylori infection, and hence whether a serology service could be introduced to reduce endoscopy workload. Methods-Eighty four patients newly presenting to their general practitioners with dyspepsia were recruited. Gold standard diagnosis of H pylori infection was obtained both by a histological examination of gastroduodenal biopsy specimens and by the "C-urea breath test (UBT). The performance of six quantitative and two qualitative enzyme linked immunosorbent assays for H pylori IgG, used according to the manufacturers' instructions, with serum samples obtained during the endoscopy visit, were compared. Results-The study population had a median age of 45 years, and the prevalence of H pyloni infection was 35%. With one exception, where the patient had received a course of anti-H pylori treatment between endoscopy and UBT, there was 100% concordance in the results of the two gold standard techniques. Discordant serology results were more common in patients aged >50 years (42% of the total) than in younger patients (21%), and this was most noticeable in uninfected patients. The sensitivity of the kits was good (90-100%), but specificity was more variable (76-96%), and the rate of equivocal results was unacceptably high in some cases (0-12%). The overall accuracy of the kits ranged from 83 to 98%. Two kits in particular performed well (Pylori-Elisa II, BioWhitaker and Premier, Launch; qualitative) with 98% and 100% accuracy, respectively. Conclusions-In a symptomatic population with a prevalence of H pyloni infection of 35%, particularly in patients aged <50 years, some but not all serology kits may be used as a highly accurate and inexpensive alternative to the gold standard techniques.