Immunocytochemical localization of oestrogen receptors in perichondrium of antlers in red deer (Cervus elaphus)

Remodelling of cancellous bone of antlers to compact bone can be stimulated by administration of oestrogens and previous work has demonstrated the presence of specific oestrogen binding in this tissue. In this study the presence of oestrogen receptors (ER) in antler tissue from red deer males was examined by immunocytochemistry using a monoclonal mouse anti-human ER serum. Strong positive staining was detected in the tip regions of immature antlers and was confined primarily to the cells forming a fibrous layer of the perichondrium. This finding indicates that the effects of oestrogens on remodelling of cancellous bone of the antler may be mediated indirectly by the surrounding connective tissue layers.

Mutation frequency in the lacI gene of liver DNA from lambda/lacI transgenic mice following the interaction of PCBs with iron causing hepatic cancer and porphyria

The synergistic interaction of iron overload, AHR: genotype and exposure to a mixture of polychlorinated biphenyls (PCBs) (Aroclor 1254) in mice leads to hepatic porphyria, oxidative DNA damage and cancer. In humans, hepatocellular cancer is associated with iron overload and hepatic porphyria. Neither the mechanism of hepatic carcinogenesis induced by PCBs in rodents nor hepatocellular cancer induced by iron and porphyria in humans are understood. To test the hypothesis that chronic interaction of iron and PCBs may induce mutagenesis in liver DNA, lambda /lacI transgenic C57BL/6 mice were given iron dextran (600 mg iron/kg) and then administered Aroclor 1254 in the diet (0.01%) for 7 weeks. Hepatic iron, CYP1A activity and CYP1A1/1A2 protein were elevated >20-fold as a result of iron or Aroclor treatments, respectively, but porphyria with associated histological changes only developed in the combined iron/Aroclor treatment group. lambda/lacI shuttle vectors were isolated from liver genomic DNA and the mutational frequency (MF) in the lacI gene determined. Both iron and Aroclor treatments alone caused significant small increases in MF (1.5- and 1.4-fold, respectively), however, the MF following the combined iron and Aroclor treatment (1. 6-fold) was not greater than the additive effects. In contrast, the MF was significantly elevated (4.7-fold) in liver DNA of mice 2 weeks following five daily doses of N-nitrosodimethylamine (4 mg/kg). These studies demonstrate that neither PCBs nor iron overload caused marked point mutations even in a combination regime that leads to oxidative damage and cancer. There was also no strong evidence either that porphyrins or chronic CYP1A1 expression induced by the PCBs after this period caused marked point mutagens or simple deletions. Hence, to understand the PCBs-iron synergism more complex scenarios than point mutations or simple deletions must be invoked.

Partners' expressed emotion and the control and management of type 1 diabetes in adults

OBJECTIVE

"Expressed emotion" (EE) refers to a set of valid and reliable measures of family emotional attitudes, which are robust predictors of illness course in several psychiatric conditions and which have recently been studied in some medical conditions. We hypothesised that high EE in partners of diabetes patients would be associated with poorer glucose control, management of and adaptation to diabetes.

METHODS

Sixty adult Type 1 diabetes patients, who were attending routine clinics at a specialist diabetes centre, and their partners were interviewed separately and completed various questionnaire measures. Partners' EE was rated from a modified Camberwell Family Interview; patients were interviewed to assess self-management practices. Glycated hemoglobin (HbA(1c)) was the measure of glucose control.

RESULTS

Only 10/60 (17%) partners were classified as high EE. Patients with high-EE partners had significantly worse self-management scores, more negative appraisal of diabetes, and higher depression scores than those with low-EE partners, but there was no association between EE measures and HbA(1c).

CONCLUSIONS

In contrast to findings from previous research on the families of patients with psychiatric illnesses, only a minority of partners of adult patients with Type 1 diabetes are classified as high-EE. We found no evidence that partners' EE was related to patients' blood glucose control.

Effectiveness of two fluoride dentifrices to arrest root carious lesions

PURPOSE

To compare the effectiveness of Prevident 5000 Plus (5,000 ppm F) and Colgate Winterfresh Gel (1100 ppm F) to arrest root carious lesions.

MATERIALS AND METHODS

201 subjects with at least one root carious lesion were recruited from dental school patients. They were randomly assigned to use either Prevident 5000 Plus (5000 ppm F) or Colgate Winterfresh Gel (1100 ppm F) as sodium fluoride in the same silica base. Measurements of lesion hardness, area, distance from the gingival margin, cavitation and plaque were recorded at baseline and after 3 months by a single examiner.

RESULTS

After 3 months 38% of subjects using Prevident 5000 Plus and 10% using Winterfresh Gel had one or more lesions that had become hard (P < 0.001). Non-cavitated lesions at baseline were more likely to become hard than cavitated lesions. Compared to the Winterfresh group there was significant increase in the distance from the base of the lesion to the gingival margin and plaque scores were reduced in those using Prevident 5000 Plus.

A six-week clinical efficacy study of a tooth whitening tartar control dentifrice for the removal of extrinsic tooth stain

The objective of this double-blind clinical study was to investigate the tooth whitening efficacy of a new commercially available calculus-inhibiting dentifrice (Colgate Tartar Control Plus Whitening Fluoride dentifrice) containing tetra-sodium pyrophosphate, sodium tripolyphosphate, and PVM/MA copolymer in a 0.243% sodium fluoride/silica base (test dentifrice), compared to a commercially available, non-tooth whitening dentifrice containing 0.243% sodium fluoride in a silica base (control dentifrice). Following a baseline examination for, extrinsic tooth stain, qualifying adult male and female subjects from the Manchester, United Kingdom area were randomized into two treatment groups which were balanced for gender, age and level of extrinsic tooth stain. Subjects were instructed to brush their teeth twice daily (morning and evening) for one minute with their assigned dentifrice using a soft-bristled toothbrush. Examinations for extrinsic tooth stain were repeated after six weeks' use of the study dentifrices. Seventy-nine(79) subjects complied with the protocol and completed the entire study. At the six-week examination, subjects assigned to the test dentifrice treatment group exhibited statistically significant reductions of over 40% with respect to both extrinsic tooth stain area and extrinsic tooth stain intensity relative to those subjects assigned to the control dentifrice treatment group.

Cortical cell death induced by IL-1 is mediated via actions in the hypothalamus of the rat

The cytokine IL-1 mediates diverse forms of neurodegeneration, but its mechanism of action is unknown. We have demonstrated previously that exogenous and endogenous IL-1 acts specifically in the rat striatum to dramatically enhance ischemic and excitotoxic brain damage and cause extensive cortical injury. Here we tested the hypothesis that this distant effect of IL-1 is mediated through polysynaptic striatal outputs to the cortex via the hypothalamus. We show that IL-1beta injected into the rat striatum with the excitotoxin alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (S-AMPA) caused increased expression of IL-1beta (mRNA and protein) mainly in the cortex where maximum injury occurs. Marked increases in IL-1beta mRNA and protein were also observed in the hypothalamus. S-AMPA, injected alone into the striatum, caused only localized damage, but administration of IL-1beta into either the striatum or the lateral hypothalamus immediately after striatal S-AMPA resulted in widespread cell loss throughout the ipsilateral cortex. Finally we showed that the cortical cell death produced by striatal coinjection of S-AMPA and IL-1beta was significantly reduced by administration of the IL-1 receptor antagonist into the lateral hypothalamus. These data suggest that IL-1beta can act in the hypothalamus to modify cell viability in the cortex. We conclude that IL-1-dependent pathways project from the striatum to the cortex via the hypothalamus and lead to cortical injury, and that these may contribute to a number of human neurological conditions including stroke and head trauma.

A celebration of 100 years' achievement in child health

This, the second of a two-part article, will reflect upon the gains made in the health and welfare of children within the UK over the last 50 years of the 20th century. It will show how government reforms covering health, welfare, and education have continued to improve all aspects of children's lives. It will also show how nursing, midwifery, and health visiting have tried to continue to meet the changing needs of children and their families. Lastly, it will highlight the increasing rate of change during this time and predict what may await children and young people in the first part of the new millennium.

Highly purified CD34+ cells isolated using magnetically activated cell selection provide rapid engraftment following high-dose chemotherapy in breast cancer patients

The primary objective of this study was to evaluate the safety of infusion of CD34+ cells, selected using a clinical scale magnetically activated cell sorting device, assessed by time to hematological engraftment and incidence of adverse events. Secondary objectives included evaluation of device performance in terms of purity and recovery of the CD34+ cell product. Breast cancer patients suitable for transplantation received cyclophosphamide and filgrastim for mobilisation, followed by three leukaphereses. The products of the first two leukaphereses underwent CD34+ cell selection. The product of the third leukapheresis was cryopreserved unmanipulated. Following high-dose cyclophosphamide, thiotepa and carboplatin, selected CD34+ cells were infused. In 54 patients who received selected cells only, the median time to platelet recovery and neutrophil recovery was 11 days (range 5-51) and 9 days (range 5-51), respectively. There were no adverse events associated with infusion of selected cells. A total of 126 leukapheresis samples was available before and after selection for central CD34+ analysis. The median purity was 96.1% (27.4-99.4) and the median recovery was 52. 3% (15.2-146.3). These data show that cells selected using magnetically activated cell selection provide safe and rapid engraftment after high-dose therapy. Bone Marrow Transplantation (2000) 25, 243-249.

Effects of an angiotensin-converting-enzyme inhibitor, ramipril, on cardiovascular events in high-risk patients

BACKGROUND

Angiotensin-converting-enzyme inhibitors improve the outcome among patients with left ventricular dysfunction, whether or not they have heart failure. We assessed the role of an angiotensin-converting-enzyme inhibitor, ramipril, in patients who were at high risk for cardiovascular events but who did not have left ventricular dysfunction or heart failure.

METHODS

A total of 9297 high-risk patients (55 years of age or older) who had evidence of vascular disease or diabetes plus one other cardiovascular risk factor and who were not known to have a low ejection fraction or heart failure were randomly assigned to receive ramipril (10 mg once per day orally) or matching placebo for a mean of five years. The primary outcome was a composite of myocardial infarction, stroke, or death from cardiovascular causes. The trial was a two-by-two factorial study evaluating both ramipril and vitamin E. The effects of vitamin E are reported in a companion paper.

RESULTS

A total of 651 patients who were assigned to receive ramipril (14.0 percent) reached the primary end point, as compared with 826 patients who were assigned to receive placebo (17.8 percent) (relative risk, 0.78; 95 percent confidence interval, 0.70 to 0.86; P<0.001). Treatment with ramipril reduced the rates of death from cardiovascular causes (6.1 percent, as compared with 8.1 percent in the placebo group; relative risk, 0.74; P<0.001), myocardial infarction (9.9 percent vs. 12.3 percent; relative risk, 0.80; P<0.001), stroke (3.4 percent vs. 4.9 percent; relative risk, 0.68; P<0.001), death from any cause (10.4 percent vs. 12.2 percent; relative risk, 0.84; P=0.005), revascularization procedures (16.3 percent vs. 18.8 percent; relative risk, 0.85; P<0.001), cardiac arrest (0.8 percent vs. 1.3 percent; relative risk, 0.62; P=0.02), [corrected] heart failure (9.1 percent vs. 11.6 percent; relative risk, 0.77; P<0.001), and complications related to diabetes (6.4 percent vs. 7.6 percent; relative risk, 0.84; P=0.03).

CONCLUSIONS

Ramipril significantly reduces the rates of death, myocardial infarction, and stroke in a broad range of high-risk patients who are not known to have a low ejection fraction or heart failure.

Achievements in child health over the first half of the 20th century

This article will reflect upon the gains made in the health and welfare of children in the UK over the first half of this century. It will discuss how government reforms covering health, welfare and education have improved all aspects of children's lives and the contribution made by the relatively new professions of nursing, midwifery and health visiting. Finally, it will show how changing attitudes towards children and the two World Wars culminated in international recognition of children's rights. A future article will highlight the increasing rate of change seen in the second half of this century.

Loss-of-function mutations in the cathepsin C gene result in periodontal disease and palmoplantar keratosis

Papillon-Lefèvre syndrome, or keratosis palmoplantaris with periodontopathia (PLS, MIM 245000), is an autosomal recessive disorder that is mainly ascertained by dentists because of the severe periodontitis that afflicts patients. Both the deciduous and permanent dentitions are affected, resulting in premature tooth loss. Palmoplantar keratosis, varying from mild psoriasiform scaly skin to overt hyperkeratosis, typically develops within the first three years of life. Keratosis also affects other sites such as elbows and knees. Most PLS patients display both periodontitis and hyperkeratosis. Some patients have only palmoplantar keratosis or periodontitis, and in rare individuals the periodontitis is mild and of late onset. The PLS locus has been mapped to chromosome 11q14-q21 (refs 7, 8, 9). Using homozygosity mapping in eight small consanguineous families, we have narrowed the candidate region to a 1.2-cM interval between D11S4082 and D11S931. The gene (CTSC) encoding the lysosomal protease cathepsin C (or dipeptidyl aminopeptidase I) lies within this interval. We defined the genomic structure of CTSC and found mutations in all eight families. In two of these families we used a functional assay to demonstrate an almost total loss of cathepsin C activity in PLS patients and reduced activity in obligate carriers.

The Canadian Study of Cardiac Transplantation. Atherosclerosis. Investigators of the CASCADE Study

OBJECTIVES

To describe risk factors associated with the development of transplantation coronary artery disease (TCAD).

DESIGN

A retrospective study of the Canadian experience.

PATIENTS

Seven hundred and nineteen patients with follow-up of at least 12 months following transplantation and a minimum of one coronary angiogram were analyzed.

RESULTS

Two hundred and fourteen patients (30%) developed angiographic evidence of TCAD during an average follow-up of 50+/-25 months. Actuarial freedom rate from TCAD averaged 60%, and survival averaged 85% five years following transplantation. Abnormal coronary angiograms increased from 11% to 40% between the first and the fifth year following transplantation. The Cox multivariate final model showed that recipients of donor hearts of 50 years and older (RR 4.35, 95% CI 2.32 to 8.15), patients with two or more episodes of acute rejection (RR 1.56, 95% CI 1.11 to 2.21) and patients with a diagnosis of ischemic cardiomyopathy before transplantation (RR 1.38, 95% CI 1.03 to 1.84) were at higher risk of TCAD. The same risk factors also had a significant effect on survival, although patients who were administered a hepatic hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitor during follow-up had a higher survival rate (95% versus 85%, P=0.01) five years following heart transplantation.

CONCLUSIONS

Recipients of hearts from older donors, patients with an ischemic heart disease before transplantation and those with several episodes of acute rejection are at increased risk for TCAD. Patients who are administered an HMG-CoA reductase inhibitor during follow-up have a higher survival rate five years following transplantation.

Antimicrobial susceptibility of enterococci recovered from commercial swine carcasses: effect of feed additives

Enterococcus faecium is an important nosocomial pathogen often displaying multiple antibiotic resistance. The increase in clinical isolates can be attributed in part to hospital practices in antibiotic usage, but there is concern that antibiotic-resistant strains might also originate in animals fed rations containing antibiotic growth promoters. Ingestion of meat from carcasses contaminated with faecal enterococci might then result in human colonization or resistance gene transfer to human enterococci. Because there are few comparisons of bacteria isolated from matched animals that have, or have not, been fed a diet containing antibiotic, two such groups of pig carcasses were sampled at a commercial abattoir. Forty isolates from each group of pigs were tested for their resistance to avilamycin and tylosin. Although a modest number of pigs was examined, and the number of strains of E. faecium tested was small, there was no evidence that the feeding of a growth promoter caused selection of enterococci resistant to tylosin or avilamycin.

Aortic dissection, patent ductus arteriosus, iris hypoplasia and brachytelephalangy in a male adolescent

We describe a 14-year-old male with dissection of the descending aorta, bilateral iris hypoplasia, striae distensae and brachytelephalangy, the latter being most marked in the thumbs. Inguinal herniae and a patent ductus arteriosus were surgically repaired in infancy. The pattern of abnormalities may constitute a previously undescribed syndrome. The proband died suddenly at the age of 17 years.

Tamoxifen induces G:C-->T:A mutations in the cII gene in the liver of lambda/lacI transgenic rats but not at 5'-CpG-3' dinucleotide sequences as found in the lacI transgene

Tamoxifen, a rat liver carcinogen, can induce mutations in the lacI gene in the livers of lambda/lacI transgenic rats. However, the presence of persistent tamoxifen adducts on the liver DNA raises the possibility that some contribution to the mutagenesis from ex vivo mutations during the in vitro lacI assay cannot be ruled out. To address this issue, mutagenesis at the cII gene of the transgenic shuttle vector was determined using a selection based assay which is unaffected by the presence of tamoxifen-DNA adducts. Female lambda/lacI transgenic rats were dosed orally with tamoxifen (20 mg/kg body wt) daily for 6 weeks, causing a 3.2-fold increase in the mutant frequency (MF) in the cII gene compared with that obtained with solvent treated animals. This was similar to the MF found previously at the lacI gene and confirms that tamoxifen is mutagenic in vivo. The major class of mutation induced by tamoxifen in the cII gene was G:C-->T:A transversions as was found previously in the lacI gene. However, in the one unreplicated study of mutations in the p53 gene of liver tumours induced by tamoxifen, no G:C-->T:A transversions were found; possible differences between mutagenesis in normal and tumour tissues are explored. The major proportion of the G:C-->T:A transversions occurred at 5'-CpG-3' dinucleotide (CpG) sites in the lacI gene, but not at such sites in the cII gene. The methylation of CpG sites greatly enhances the targeting of deoxyguanosine by carcinogens, thus this finding might be explained by differences in the methylation patterns at their respective CpG sites; however, nothing is known about the methylation status of either the lacI nor the cII gene in this transgenic rat. This study raises the important issue of which target genes (mammalian or transgenic) should be used as endpoints in mammalian mutagenesis assays.

Efficacy of a mouthrinse containing 0.05% cetylpyridinium chloride for the control of plaque and gingivitis: a 6-month clinical study in adults

The objective of this 6-month, double-blind, clinical study, conducted following the American Dental Association (ADA) guidelines, was to provide an assessment of the effectiveness of a newly developed mouthrinse containing 0.05% cetylpyridinium chloride (CPC) for the control of supragingival dental plaque and gingivitis. Adult men and women from the Manchester, England, area were entered in the study, and stratified into two treatment groups (CPC mouthrinse and control mouthrinse), which were balanced for baseline Quigley-Hein Plaque Index scores and baseline Löe-Silness Gingival Index scores. Participants were given an oral prophylaxis and instructed to brush their teeth twice daily (morning and evening) for 1 minute with a soft-bristled toothbrush and fluoride dentifrice provided, immediately followed by rinsing for 30 seconds with 15 cc of their assigned mouthrinse. Examinations for supragingival plaque and gingivitis were conducted after 3 months' and again after 6 months' participation in the study. One hundred eleven participants complied with the protocol and completed the entire 6-month clinical study. At both the 3- and 6-month study examinations, the CPC mouthrinse group exhibited statistically significantly less supragingival plaque and gingivitis than did the control mouthrinse group. At the 6-month examination, the magnitude of these differences met or exceeded 24% for all 4 parameters measured (28.2% for Quigley-Hein Plaque Index, 63.4% for Plaque Severity Index, 24.0% for Löe-Silness Gingival Index, and 66.9% for Gingivitis Severity Index). The magnitude of the reductions in supragingival plaque and gingivitis were adequately large to support a claim of efficacy, in accordance with the criteria provided by the published guidelines of the ADA for the demonstration of the efficacy of a chemotherapeutic agent for the control of supragingival plaque and gingivitis. Thus, the results of this 6-month clinical study support the conclusion that a newly developed mouthrinse containing 0.05% cetylpyridinium chloride provides a statistically significant, clinically relevant level of efficacy for the control of supragingival plaque, and for the control of gingivitis, in accordance with the criteria provided by current ADA guidelines.

Extraction of teeth over 5 years in regularly attending adults

OBJECTIVES

This prospective study was conducted to describe the incidence of tooth extraction in a group of regularly attending adults and to assess factors that are predictive of tooth loss.

METHODS

Baseline and annual incremental clinical data were obtained from 23 general dental practitioners on a group of their regularly attending, dentate adult patients over a 5-year period. The patients completed a postal questionnaire with questions relating to dental health behaviours, attitudes and knowledge, and social factors.

RESULTS

Complete clinical data were obtained from 2799 patients. Four hundred and seventy (17%) patients underwent extractions, 72% of which were posterior teeth. The majority of extractions were for reasons other than caries (79%). Bivariate analyses revealed many significant differences between patients who underwent extractions and those who did not, with respect to the clinical, social, behavioural and attitudinal variables. The logistic regression model for tooth loss included three clinical variables, number of teeth, crowns and sites with recession. Other variables in the final model included the dentist's and patient's prediction of treatment need, having sensitive teeth, having a sweet tooth, living alone and smoking. The sensitivity for the model was 0.57 with specificity 0.72.

CONCLUSIONS

This study is unique in its examination of patients and has highlighted that both clinical and other factors are important in predicting who will undergo extractions. Future investigations should assess the consequence of having extractions in terms of health benefit or detriment.

Asthma management with HFA-BDP (Qvar)

This report reviews the role of hydrofluoroalkane-beclomethasone dipropionate (HFA-BDP; Qvar, 3M, Laughborough) in the management of asthma, based on pharmacokinetic, efficacy and safety clinical trial data presented at a satellite symposium to the European Respiratory Society in 1998. Qvar provides equivalent efficacy and safety to chlorofluorocarbon-BDP at about half the dose.

Interval or permanent nonoperative management of acute type A aortic dissection

HYPOTHESIS

Selected patients with acute type A (ascending) aortic dissection who are treated with delayed operation or nonoperative therapy may have better early and short-term outcomes than was previously expected.

DESIGN AND SETTING

Retrospective cohort at a university hospital.

SUBJECTS

Data on 75 patients with acute or chronic type A aortic dissection treated at one institution from January 1, 1985, to November 30, 1997, were analyzed. Of these 75 patients, 34 (21 male and 13 female, with a mean age of 65.5 years) did not undergo initial operative treatment, and 15 (10 male and 5 female, with a mean age of 72.6 years) never underwent surgery. For the 19 patients who underwent delayed surgery, the mean period between aortic dissection and intervention was 11.4+/-4.83 days. The follow-up period ranged from 0.27 to 149 months, with a mean of 20.2 months.

MAIN OUTCOME MEASURES

Vascular complications, hospital mortality, and early survival.

RESULTS

Reasons for interval delay in surgical treatment included initial misdiagnosis or delay in diagnosis (13 [68%] of 19), need to address significant comorbidity (4 [21%] of 19), and initial refusal of operative intervention (2 [11%] of 19). For the 15 patients treated entirely by medical therapy, reasons for electing nonoperative management included extensive comorbidity (5 [33%] of 15), refusal of surgical intervention (6 [40%] of 15), and misdiagnosis or long delay in diagnosis (4 [27%] of 15). Of the 34 patients, 15 (44%) presented with moderate or severe aortic insufficiency, 5 (14%) had evidence of pericardial effusion, 6 (21%) had evidence of concomitant coronary ischemia on electrocardiogram, and 8 (24%) had extension of the dissection into the descending aorta. Four patients (11.8%) died while in the hospital. Of the 34 patients, 30 (88%) who underwent either delayed or no surgery received aggressive medical treatment (beta-adrenergic blocking agents and afterload-reducing agents) and were discharged from the hospital. All patients who were operative candidates in the interval treatment group survived to reach definitive operation. There was no statistically significant difference in short-term survival between the group of patients undergoing delayed surgery or medical treatment only and the group of 41 patients undergoing early operation (P = .42).

CONCLUSIONS

Immediate surgical therapy is still recommended for acceptable operative candidates with acute type A aortic dissection who seek immediate treatment. However, this study permits the following 2 conclusions: (1) patients with type A aortic dissection who are referred or whose conditions are diagnosed several days after presentation have survived the early dangerous period and can safely undergo surgery semielectively (rather than emergently); and (2) selected patients who are not considered operative candidates and who survive the initial type A aortic dissection without complication may be treated with aggressive medical therapy and achieve acceptable early and short-term outcomes, which is better than previously expected.

Multiple roles for the Wilms' tumor suppressor, WT1

Wilms' tumor is a childhood kidney tumor that is a striking example of the way that cancer may arise through development gone awry. A proportion of these tumors develop as a result of the loss of function mutations in the Wilms' tumor suppressor gene, WT1. Inherited mutations in the WT1 gene can lead to childhood kidney cancer, severe gonadal dysplasia, and life-threatening hypertension. Knockouts show that the gene is essential for the early stages of kidney and gonad formation. These tissues are completely absent in null mice. The WT1 gene encodes numerous protein isoforms, all of which share four zinc fingers. There is a large body of evidence supporting the notion that WT1 is a transcription factor, particularly a transcriptional repressor. Recently, however, we obtained evidence that WT1 colocalizes and is physically associated with splice factors. What is more, one alternative splice isoform of WT1 containing three amino acids, Lys-Thr-Ser (KTS; inserted between zinc fingers 3 and 4) is preferentially associated with splice factors, whereas the other alternative splice version, lacking these three amino acids, preferentially associates with the transcriptional apparatus. Both genetic and evolutionary considerations suggest that these two different forms of the protein have different functions. We will discuss recent evidence to further implicate WT1 in splicing. Our results raise the possibility that regulation of splicing is a crucial factor in the development of the genitourinary system, and that tumors may arise through aberrant splicing. To pursue the regulation and function of WT1 in whole animals, we have been introducing the human gene and large flanking regions cloned in yeast artificial chromosomes directly into mice. These studies have allowed us to dissect the function of WT1 at late as well as at early stages in organogenesis and to identify new sites and surprising new potential functions for the gene.