Evidence for clonal anergy as a mechanism responsible for the maintenance of transplantation tolerance

The main stimulus triggering early acute allograft rejection is known to be delivered by the allogeneic "passenger" leukocytes present within the grafts. Once these cells have been replaced by cells of recipient origin, subsequent rejection episodes are generally less frequent and less acutely destructive. How this replacement affects the cell populations responsible for allograft rejection is not known. Here we report that rat alloreactive non-cytotoxic AS (RT1I) anti-August (RT1c) CD4+ T cells, that were shown to be specific for RT1.Bc+ August spleen stimulators, were able to cause acute rejection of normal August kidney allografts transplanted into sublethally irradiated AS recipients. These cells, however, failed to reject passenger cell-depleted (PCD) August kidneys, despite the substantial expression of RT1.Bc+ products on the graft tubular epithelium. In experiments in vitro, August kidney tubular epithelial cells expressing RT1.Bc+ antigens were found to be unable to stimulate the alloreactive T cells to proliferate. Moreover, preincubation with class II-positive August kidney epithelial cells specifically abrogated the alloreactivity of the T cells. Adding recombinant interleukin-2, however, restored the response to alloantigens. These results are consistent with the hypothesis that T cell populations capable of mediating early acute allograft rejection are different from those mediating late rejection, when donor passenger leukocytes are no longer present. They also suggest clonal anergy as one of the mechanisms responsible for maintaining long-term transplantation tolerance.

Mediation of acute but not chronic rejection of MHC-incompatible rat kidney grafts by alloreactive CD4 T cells activated by the direct pathway of sensitization

It has been previously postulated that there are two pathways of sensitization of MHC-incompatible kidney allografts: a direct pathway in which the host responder T cells are activated by MHC-incompatible passenger dendritic cells of the graft, and an indirect pathway, in which graft alloantigens are processed like "nominal" T cell antigens by host accessory cells, and presented as self-MHC restricted moieties. We show here that a rat AS anti-August alloreactive CD4+ T cell line, and a presumptive clone, activated through the direct pathway are capable in an adoptive transfer model of initiating rejection of normal August kidney grafts. However, neither the T cell line nor the presumptive clone initiates rejection of passenger cell-depleted August kidneys. The results support the hypothesis that direct pathway--sensitized T cells play a dominant role in early acute rejection, but not in chronic rejection.

Hepatitis B and delta virus infection among "at risk" populations in south east London

STUDY OBJECTIVE

The hepatitis delta virus (HDV) contributes significantly to the morbidity and mortality of hepatitis B virus (HBV) infection, which is particularly prevalent among intravenous drug users and male homosexuals. A recent report has indicated that HDV first appeared in the South East London intravenous drug using population in 1982. The aim of the present study was to assess the prevalence of HDV in these two groups at risk of HBV infection in South East London.

DESIGN

The study was a cohort analysis of HBV and delta virus serum markers, stratified temporally and with respect to intravenous drug use and sexual practice.

SETTING

This was a population study of 372 consecutive intravenous drug users attending a local drug rehabilitation centre and 1481 subjects seen at a sexually transmitted disease clinic in the same area, during the years 1979 to 1988.

MEASUREMENTS AND MAIN RESULTS

Of 372 intravenous drug users, 195 (52.4%) had evidence of current or past infection with HBV, of whom 17 had chronic HBV infection--a carriage rate of 8.7%. Twelve (70.6%) of these 17 also had chronic HDV infection--the first cases being identified in 1984. By comparison, 406 (27.4%) of the sexually transmitted disease clinic patients had been been exposed to HBV, 32 having chronic HBV: a carriage rate of 7.9% (7.5% v 9.4% among male homosexuals v male heterosexuals). Ten had been exposed to HDV (the first case in 1980) but only two (who did not admit to intravenous drug use) had chronic HDV infections (p less than 0.0005 v the rehabilitation centre patients).

CONCLUSIONS

Although the HBV carriage rate is very similar in these two populations, chronic HDV infections were mainly confined to intravenous drug users. However, reports from the USA and France indicate spread of delta virus to the male homosexual community and, since there is clearly a pool of HDV in SE London, vaccination against HBV in these risk groups in likely to be cost-effective and should be actively encouraged.

Fatal esophageal-arterial fistula 17 years following tetralogy of Fallot repair

Blalock-Taussig shunts (subclavian to pulmonary anastomoses) have remained the most effective palliation in cyanotic heart disease. Late complications are rare but can be devastating. The case of a 26-year-old female with tetralogy and an original Blalock shunt constructed at age four years is reported. Despite subsequent primary repair of the tetralogy and presumed ligation of the Blalock shunt, the patient succumbed to a fatal hemorrhage due to esophageal-arterial fistula involving the Blalock shunt. The circumstances leading to this dramatic outcome are outlined and discussed. It is important for cardiologists caring for congenital heart disease patients to be aware of the late complications of congenital heart surgery, and carry out the proper follow-up investigations.

Delayed haemolytic transfusion reactions in patients with sickle cell disease

We describe two cases which illustrate the difficult diagnostic and therapeutic problems posed by delayed haemolytic transfusion reactions in patients with sickle-cell disease. The cases emphasize the need for meticulous phenotypic and serological assessment of sickle-cell patients prior to transfusion therapy.

Rapid identification of specific genes in E. coli by hybridization to membranes containing the ordered set of phage clones

A simplified protocol for the hybridization of labeled oligonucleotides and other radiolabeled DNAs to membranes is described and used for the detection of specific recombinant phage in the ordered miniset collection representing virtually the entire E. coli genome.

Entrapping of the clotted intra-aortic balloon in the descending aorta

Percutaneous insertion of a catheter for intra-aortic balloon pumping (IABP) was introduced in 1979 by Bregman and Casarella and has become a popular technique. Rupture of the balloon, allowing clot to form inside it, is rare. When the clot is large, it may cause entrapping of the balloon. This is a potentially dangerous complication of IABP. We are aware of only one case report of this complication, by Aru and co-workers. The entrapping of the balloon in their report occurred at the site of insertion in the femoral artery. We report here a case in which the entrapping occurred in the descending aorta, and its removal required extensive exposure of the aortic bifurcation.

Qualitative methods in operations research on contraceptive distribution systems: a case study from Nigeria

This article discusses the application of qualitative methods in operations research on a family planning service delivery system. Market traders in Ibadan, Nigeria were trained to sell oral contraceptives, condoms, and spermicidal foaming tablets in a collaborative research project of the Fertility Research Unit of the University College Hospital, Ibadan, and the Center for Population and Family Health of Columbia University. Focus group discussion, participant observation, and semi-structured interviews were used to investigate the cultural acceptability of distribution of contraceptives in the market places and the motivations of participating traders. The strength of the market associations was a factor influencing acceptance of the project and the number of customers for the traders' other wares were found to positively influence the volume of sales of contraceptives. Traders were motivated by the status associated with participating in a program of a well-known health institution. Findings from qualitative research suggest areas for quantitative studies and vice versa in an interactive process.

Localization of the gene for human proliferating nuclear antigen/cyclin by in situ hybridization

Proliferating cell nuclear antigen (PCNA)/cyclin has been localized by in situ hybridization to the short arm of human chromosome 20 with a peak of grains over band 20p13. In addition, there were two strong secondary peaks of grains over 11p15.1 and Xp11.4 indicating the presence of two related genes in man.

Mapping of class alpha glutathione S-transferase 2 (GST-2) genes to the vicinity of the d locus on mouse chromosome 9

Recombinant inbred strains of mice were used to localize the genes coding for the class alpha glutathione S-transferase 2 (Gst-2). The genes showed three distinct strain distribution patterns, indicating that they occur in at least three clusters separable by recombination. All three clusters are located in the vicinity of the d locus on mouse chromosome 9, but two of them are closer to d than the third. Linked to Gst-2 on mouse chromosome 9 are two enzyme-encoding loci, Pgm-3 and Mod-1. The human counterparts of Gst-2, Pgm-3, and Mod-1 map to 6p12, 6q12, and 6q12, respectively. Thus, the pericentric region of human chromosome 6 has its homolog in the segment spanning Gst-2, Pgm-3, and Mod-1 on mouse chromosome 9. The fact that the syntenic group extends across the centromere of human chromosome 6 can best be explained by a pericentric inversion postulated to have taken place in the primate lineage leading to Catarhini.

Genetic heterogeneity of the human glutathione transferases: a complex of gene families

The glutathione transferases (GSTs) are involved in the metabolism of a wide range of compounds of both exogenous and endogenous origin. There is evidence that deficiency of GST may increase sensitivity to certain environmentally derived carcinogens. In contrast, elevated expression has been implicated in resistance to therapeutic drugs. The GSTs are the products of several gene families. This review summarizes the present knowledge of the genetic interrelationships between the various isoenzymes, their deficiencies and the physical locations of their genes.

An approach to the teaching of host/parasite population modelling

Computer-aided learning is considered to be useful in the teaching of host/parasite population modelling. The STELLA programme for the Apple Macintosh microcomputer allows dynamic models to be developed by drawing a diagram of the interactions and then defining the relationships between variables in terms of simple mathematics or as graphs. Our experience in using this programme for project-based teaching is described.

Resistance studies with ofloxacin

The selection of ofloxacin-resistant mutants from susceptible wild-type bacterial populations was investigated by three methods. Resistant mutants selected from populations of Escherichia coli (NCTC 10418) and Staphylococcus aureus (NCTC 6571) by single-step passage at either four or eight times the MIC occurred at a frequency of less than 1 x 10(-10). Ofloxacin-resistant mutants of Pseudomonas aeruginosa (NCTC 10662), selected at four times the MIC, occurred with a 100-fold greater frequency at 3.3 X 10(-8), however, mutants of this species selected at eight times the MIC, occurred at a frequency of less than 1 X 10(-10). Sequential selection of ofloxacin-resistant mutants during multiple passages at 1/2 MIC, resulted in a 16- to 32-fold increase in MICs for isolates of P. aeruginosa and Klebsiella aerogenes, a four- to eight-fold increase in MICs for some strains of E. coli and a two- to four-fold increase in MICs for Staph. aureus and Streptococcus spp. During prolonged exposure of populations of E. coli (NCTC 10418) and Staph. aureus (NCTC 6571) to concentrations of ofloxacin at 1, 10 and 100 times the MIC no resistant-mutants were selected after seven days incubation. In similar experiments with P. aeruginosa (NCTC 10662) ofloxacin-resistant mutants were selected from populations exposed to the MIC which required 64 mg/l ofloxacin for inhibition. No ofloxacin-resistant mutants were selected from populations of P. aeruginosa (NCTC 10662) exposed to either ten or 100 times the MIC.(ABSTRACT TRUNCATED AT 250 WORDS)

The burden of illness that is imposed by drug abuse and the allocation of research monies in the field: three views

The views of politicians, experts in the field of drug abuse and randomly-selected members of the community were sought concerning the burden of illness that is imposed by the abuse of alcohol, tobacco, narcotic agents, prescribed drugs, cocaine, volatile substances, over-the-counter drugs and cannabis. Politicians and community members perceived illicit drugs to have the greatest associated burden. Experts ranked in descending order alcohol, tobacco, narcotic agents, prescribed drugs, cocaine, volatile substances, over-the-counter drugs and then cannabis to have the greatest burden of illness. Priorities that were perceived by each group for research funding corresponded with their judgements of the burden of illness. Experts' views on the burden of illness most closely matched the data that are available on drug-associated mortality. It is suggested that unless a close correspondence among the views of the three groups is present, conflict in regards to allocation of resources is likely.

Genomic organization of human centromeric alpha satellite DNA: characterization of a chromosome 17 alpha satellite sequence

We characterized a recombinant clone E7 containing a 1.6-kb Eco RI insert of human alpha satellite DNA (alpha DNA) which hybridized in situ predominantly to the centromere of chromosome 17. Three thousand copies of this sequence were detected on chromosome 17, although a lesser number of copies were also found on the centromeres of chromosomes 11, X, and the other human chromosomes, except Y. In the human genome, sequences homologous to E7 were organized principally as five major polymorphic (Pst I) forms of tandem alpha DNA repeats with molecular weights between 2.0 and 2.7 kb. We We studied the higher-order organization of these major forms using a series of 12 cosmid clones. Close linkage of the different polymorphic forms was demonstrated, with no two cosmids showing an identical linkage pattern. Six of the cosmid clones carried a considerable amount (20-25%) of nonhomologous (non-alpha) DNA, indicating that the repeat arrays are relatively frequently interrupted by other genomic DNA. In none of the cosmid inserts were the repeat arrays bound on both sides by non-alpha DNA, suggesting that short arrays are not common. However, some of the intervening non-alpha DNA sequences were relatively short, and vary in size from 6 to 24 kb. Our results suggest an irregular and complex pattern of organization of alpha DNA in the human genome.

Simple, rapid 125I-labeled cyclosporine double antibody/polyethylene glycol radioimmunoassay used in a pediatric cardiac transplant program

We modified the Sandoz cyclosporine radioimmunoassay because of our need for frequent clinical monitoring of cyclosporine drug levels in allo- and xenograft pediatric cardiac transplant patients. With application of a commercially available [125I]cyclosporine label in place of [3H]cyclosporine and a second antibody/polyethylene glycol (PEG) method of separation in place of charcoal separation, we simplified and enhanced the speed and precision of assay performance. Studies of 140 whole blood samples comparing this new method to the [3H]cyclosporine radioimmunoassay (RIA) method of Berk and colleagues yielded a coefficient of correlation of 0.96 (p less than 0.00001) with means of 626 and 667 ng/ml for [3H]RIA and [125I]RIA, respectively, and a regression equation of y = 28 + 1.02x. The major advantages are that total assay time is reduced to approximately 1 h; [125I]cyclosporine label is used, avoiding the problems associated with liquid scintillation counting; and precision is enhanced by separating bound and free fractions with second antibody/PEG. These modifications should provide for greater ease of assay performance and improved clinical utility of cyclosporine monitoring not only in the pediatric but also in the adult transplant patient.

Chromosome study of Presbytis cristatus: presence of a complex Y-autosome rearrangement in the male

The karyotypes of a female and of a male Presbytis cristatus are analysed. In the latter, there is a complex Y-autosome rearrangement. The phyletic position of this species, in relation to genus Colobus, previously studied, is proposed, considering the sequence of chromosomal rearrangements which occurred during their evolution. These rearrangements, in addition to the t(Y-autosome), are characterized by a high frequency of inversions, and above all, by several non-Robertsonian translocations which occurred very rarely during evolution of other Primates.

Neuroimmaturity of learning-disabled children: a controlled study

A 46-component neurological exam was administered to 119 learning-disabled children and to 152 control children, and a Neuroimmaturity Index (NI) was constructed. The results were compared by age and sex. Neuroimmaturity decreased significantly with age, and after controlling for age and sex there were statistically significant differences in NI between the learning-disabled and control children. Male children from both groups, controlling for age, tended to have a higher NI than females. Patterns of disability were related to communication skills; older learning-disabled males had difficulty writing and spelling, whereas younger female learning-disabled children had difficulty with spoken language.