Requirement for the von Hippel-Lindau tumor suppressor gene for functional epidermal growth factor receptor blockade by monoclonal antibody C225 in renal cell carcinoma

Renal cell carcinoma (RCC) is a cytologically and histologically diverse disease in which a spectrum of distinct molecular alterations occurs, including the inactivation of the von Hippel-Lindau (VHL) tumor suppressor gene, which is specific for the clear cell variant of RCC. The prognosis for RCC is poor, and, to date, no effective systemic treatment is available for this cancer. In the present study, we assessed the extent to which the transforming growth factor alpha-epidermal growth factor receptor (EGFR) autocrine loop could be used as a potential therapeutic target for RCC. Northern blot analysis of transforming growth factor alpha and EGFR revealed variable but consistent expression of these transcripts in cell lines derived from both clear cell and non-clear cell RCC variants, indicating the potential for this autocrine loop in both tumor types. The therapeutic utility of interruption of this feedback loop was determined by examining growth inhibition after the exposure of these cell lines to a humanized anti-EGFR monoclonal antibody, C225. In vitro treatment of clear cell RCC-derived cell lines lacking VHL resulted in only a modest decrease in growth rate. In contrast, non-clear cell RCC-derived cell lines that retained VHL responded significantly to C225 treatment. Transfection of VHL into VHL-negative RCC cell lines restored responsiveness to C225, indicating that this tumor suppressor gene is required for effective EGFR blockade. Growth inhibition by C225 in VHL-positive cells was linked to a requirement for VHL to up-regulate p27 in response to C225. These data provide compelling evidence that treatment modalities for RCC are likely to be strongly influenced by the molecular etiology of this phenotypically diverse cancer.

Effects of oxidised alpha-lipoic acid and alpha-tocopherol on xenobiotic-mediated methaemoglobin formation in diabetic and non-diabetic human erythrocytes in-vitro

The effects of oxidised alpha-lipoic acid and alpha-tocopherol were investigated on a human erythrocytic in vitro model of diabetic metabolic stress. Preincubation of non-diabetic and diabetic erythrocytes with oxidised alpha-lipoic acid or alpha-tocopherol resulted in marked increases in nitrite-mediated methaemoglobin formation. In contrast, oxidised alpha-lipoic acid resulted in considerable reductions in 4-aminophenol-mediated methaemoglobin formation in both diabetic and non-diabetic cells. alpha-Tocopherol showed an increase only in diabetic cells, at one time point. Monoacetyl dapsone hydroxylamine (MADDS-NHOH)-mediated methaemoglobin formation was reduced by oxidised alpha-lipoic acid in non-diabetic and diabetic cells at all three time points, although alpha-tocopherol had no effect with MADDS-NHOH. In diabetic cells only, alpha-tocopherol incubation caused a reduction in GSH levels compared with non-diabetic cells. As the agents showed pro- as well as anti-oxidant effects in this study, further studies are required to demonstrate potential diabetic benefit from alpha-lipoic acid adminstration.

Mechanisms of epithelial development and neoplasia in the metanephric kidney

Recent studies on the mechanisms of normal epithelial development in the kidney, and on the aetiology of renal neoplasms, are converging to reveal remarkably close relationships between the phenotypes and behaviours of normally-developing and neoplastic cells. Normal renal epithelia arise from two sources; those of the collecting duct system develop by arborisation of an initially-unbranched ureteric bud, in a manner similar to the development of other glandular organs, while epithelial nephrons develop via an unusual mesenchyme-to-epithelial transition. Both types of development require controlled proliferation, cell-cell and cell-matrix interactions, protease activity etc., but of the two tissues, the development of the nephrons is arguably the more complex. It includes many defined stages, signals and checkpoints that ensure that events happen at the right time, and that processes such as proliferation, apoptosis and differentiation are properly balanced. Detailed investigation of renal neoplasms has revealed some to be caused by mutations in molecules with known roles in normal nephrogenesis (e.g. Wilms' tumour and the WT-1 gene, renal cell carcinoma and the c-met receptor tyrosine kinase gene), some to be caused by mutations in genes expressed during normal development (e.g. renal cell carcinoma and the TSC-2 gene, renal cell carcinoma of the clear cell variety and the VHL gene). Furthermore, these and other tumours of unknown aetiology re-express genes such as Pax-2 that are expressed during the normal mesenchyme-to-epithelium transition but are shut off during terminal differentiation. Their re-appearance in tumours suggests that the cells have 'regressed' in an ontogenic sense, and their biology may therefore be understood most clearly by reference to the properties of normal developing cells rather than cells of a mature kidney.

Molecular cloning and characterization of a mouse gene with homology to the Duffy-antigen receptor for chemokines

The Duffy antigen receptor for chemokines (DARC) is a receptor for both CXC and CC chemokines. We have cloned a mouse gene with a predicted amino acid sequence homology of approximately 63% to human DARC and localized this gene to mouse chromosome 1 between the Xmv41 and D1Mit166 loci. We further demonstrated that, like the human gene, the mouse gene exhibits a single intron of 462 bp which interrupts the open reading frame between the codons for the seventh and eighth amino acid residues. Northern blot analyses revealed that putative mDARC mRNA is highly expressed in adult mouse spleen and skeletal muscle and in whole embryos between embryonic days 8.5 to 12. Northern blot analysis of hemangiosarcomas which develop spontaneously in the spleen of the Eker rat reveal expression of mRNAs which hybridize with both DARC and CXCR2 probes, suggesting a potential role of these receptors in the angiogenesis associated with tumor formation.

Genetic variants of the tuberous sclerosis 2 tumour suppressor gene in mouse t haplotypes

The murine t complex on chromosome 17 contains a number of homozygous lethal and semi-lethal mutations that disrupt development of the mouse embryo. We recently characterized an embryonic lethality in the rat that results from a germ-line mutation in the tuberous sclerosis 2 (Tsc-2) tumour suppressor gene (the Eker mutation). Remarkably, mouse embryos homozygous for tw8 mutation display cranial defects reminiscent of those observed in rat embryos homozygous for the Eker mutation. To determine whether the Tsc-2 gene, which is in the t complex, is mutated in tw8 or other t haplotypes, we characterized this gene in a series of t haplotype mice. Four Tsc-2 polymorphisms were identified: three in the coding region and one intronic that appeared to be common to all t haplotypes analysed. No evidence was found to argue that the Tsc-2 gene is altered in tw8 haplotype mice. However, in the tw5 haplotype we found a G to T mutation in Tsc-2 that was present only in this t haplotype. In contrast to other polymorphisms within the Tsc-2 coding region which did not result in amino acid changes in Tsc-2 gene product tuberin, this mutation substituted a phenylalanine for a conserved cysteine in tw5 tuberin. Within the t complex, the Tsc-2 gene and the putative tw5 locus appeared to map to different positions, complicating identification of Tsc-2 as a candidate for the tw5 locus and suggesting that the G to T mutation in the Tsc-2 gene may have arisen independently of the tw5 functional mutation.

Estrogen receptor activation via activation function 2 predicts agonism of xenoestrogens in normal and neoplastic cells of the uterine myometrium

The possible contribution of endocrine disrupters to human disease, particularly those compounds that modulate the estrogen receptor (ER), has recently drawn considerable attention. The tissue specificity of effects mediated by the ER is well recognized, although the mechanism of this specificity is not understood sufficiently to predict the effects of a particular ligand in different target tissues. Although the divergence of ER-mediated effects in the breast, bone, and uterine endometrium has been described, a frequently overlooked site of estrogen action is the smooth muscle of the uterus. The uterine myometrium is the tissue of origin of an extremely common hormone-responsive tumor, uterine leiomyoma, a tumor with a significant impact on women's health and a possible environmental influence. This report describes an in vitro/in vivo system for identifying the effects of ER ligands in the myometrium and elucidating their mechanism of action. Several natural and synthetic xenoestrogens were evaluated at the cellular and molecular level for their ability to mimic estrogen action in uterine myometrial tissues. Diethylstilbestrol, coumestrol, genistein, naringenin, and endosulfan were able to activate the AF2 function of the ER in vitro and demonstrated agonist activity in estrogen-responsive myometrial cells, as determined by induction of proliferation and increased message levels of progesterone receptor. Compounds that could not activate AF2 function (4-hydroxy-tamoxifen, LY117018, and LY317783) did not act as estrogen agonists. For agonists, rank order of potency was predicted by receptor affinity; however, endosulfan displayed a surprising degree of activity, despite negligible receptor binding. Additionally, diethylstilbestrol and tamoxifen demonstrated prototypical agonist and antagonist effects, respectively, in the intact myometrium of sexually mature rats. The results presented here suggest that some exogenous ER ligands may mimic the effects of endogenous estrogens on uterine leiomyoma and may contribute to a complex hormonal milieu that impacts both normal and neoplastic myometrium.

Cyclins and cell cycle checkpoints

The eucaryotic cell cycle is regulated by the periodic synthesis and destruction of cyclins that associate with and activate cyclin-dependent kinases. Cyclin-dependent kinase inhibitors, such as p21 and p16, also play important roles in cell cycle control by coordinating internal and external signals and impeding proliferation at several key checkpoints. Understanding how these proteins interact to regulate the cell cycle has become increasingly important to researchers and clinicians with the discovery that many of the genes that encode cell cycle regulatory activities are targets for alterations that underlie the development of cancer. Several therapeutic agents, such as DNA-damaging drugs, microtubule inhibitors, antimetabolites, and topoisomerase inhibitors, take advantage of this disruption in normal cell cycle regulation to target checkpoint controls and ultimately induce growth arrest or apoptosis of neoplastic cells. Other therapeutic drugs being developed, such as UCN-01, specifically inhibit cell cycle regulatory proteins.

Loss of function of the tuberous sclerosis 2 tumor suppressor gene results in embryonic lethality characterized by disrupted neuroepithelial growth and development

Germline defects in the tuberous sclerosis 2 (TSC2) tumor suppressor gene predispose humans and rats to benign and malignant lesions in a variety of tissues. The brain is among the most profoundly affected organs in tuberous sclerosis (TSC) patients and is the site of development of the cortical tubers for which the hereditary syndrome is named. A spontaneous germline inactivation of the Tsc2 locus has been described in an animal model, the Eker rat. We report that the homozygous state of this mutation (Tsc2(Ek/Ek)) was lethal in mid-gestation (the equivalent of mouse E9.5-E13.5), when Tsc2 mRNA was highly expressed in embryonic neuroepithelium. During this period homozygous mutant Eker embryos lacking functional Tsc2 gene product, tuberin, displayed dysraphia and papillary overgrowth of the neuroepithelium, indicating that loss of tuberin disrupted the normal development of this tissue. Interestingly, there was significant intraspecies variability in the penetrance of cranial abnormalities in mutant embryos: the Long-Evans strain Tsc2(Ek/Ek) embryos displayed these defects whereas the Fisher 344 homozygous mutant embryos had normal-appearing neuroepithelium. Taken together, our data indicate that the Tsc2 gene participates in normal brain development and suggest the inactivation of this gene may have similar functional consequences in both mature and embryonic brain.

Identification of a tumor-specific methylation site in the Wilms tumor suppressor gene

Malignant mesothelioma is one of the very few extrarenal neoplasms in which the Wilms tumor suppressor gene (wt1) is expressed. We examined wt1 for alterations in rat mesotheliomas, a well characterized animal model for the human disease. Southern analysis revealed a 3.5 kb EcoRI wt1 fragment readily detectable in majority of mesothelioma cell lines and primary mesotheliomas but not in normal rat tissues. Cloning and sequencing of this fragment revealed that the presence of this EcoRI fragment resulted from an inability of this enzyme to cut at a EcoRI site in intron 1 of wt1. This site contains potential motifs for cytosine methylation and treatment of mesothelioma cells with 5-azadeoxycytosine restored the normal EcoRI digestion pattern of wt1 in these cells indicating that cleavage was inhibited by methylation at this site. Southern analysis using HpaII/MspI digestion revealed no differences in methylation between mesothelioma cell lines and normal mesothelium at other CpG sites in wt1 5' region. Renal cell carcinoma lines which did not express wt1 were also methylated at this EcoRI site. Our identification of a site frequently methylated in malignant cells, independent of gene expression, provides a new model system to study determinants of site-specific methylation in tumors.

Magnetic resonance imaging of ultrasonic fields

A nuclear magnetic resonance imaging (MRI) method is described that allows noninvasive, quantitative mapping of medical ultrasound (US) fields in tissue. Application of a resonant magnetic field gradient operating at the US frequency permits detection of nanometer motions associated with ultrasound, and allows direct measurement of absolute pressure, intensity, and speed of sound. By altering gradient timing, the propagation of US fields in time and space can be observed; this enables tracking of US scattering phenomena in a tissue-equivalent medium. An experimental apparatus was constructed that combined a 515-kHz focused US transducer configured with its focus in the center of a small-bore oscillating gradient. This provided an oscillating gradient with a peak gradient strength of 0.40 T/m over a useable imaging volume of 61 cm3. When used in conjunction with 1.5-T clinical MRI system, this apparatus allowed the clear visualization of the focused US field within this volume and its propagation with time. Current limits of sensitivity indicate a noise equivalent sensitivity of 3.8 nm in displacement amplitude, 19 kPa in pressure amplitude and 12 mW/cm2 in acoustic intensity. These studies indicate that MRI can provide a new, noninvasive method for US exposimetry and the basic study of ultrasound biophysics in tissue.

Altered expression of transforming growth factor-alpha: an early event in renal cell carcinoma development

Transforming growth factor-alpha (TGF-alpha) is a multifunctional cell regulatory protein with a wide range of effects on cell growth and differentiation and has been implicated in the neoplastic transformation of a variety of cell types. Altered expression of TGF-alpha and its cognate receptor (epidermal growth factor receptor) is enhanced in human and rat renal cell carcinomas. The objective of the study reported here was to determine whether altered TGF-alpha expression is an early or late event in renal tubular oncogenesis. The immunohistochemical expression of TGF-alpha was studied in preneoplastic renal tubular lesions in a rat model of hereditary renal cell carcinoma. Strong TGF-alpha immunoreactivity was present at all stages of renal cell tumor development, including the earliest detectable dysplasias. In contrast, the non-neoplastic regenerating tubular epithelium of rat degenerative nephropathy did not stain for TGF-alpha, although this tissue exhibited a proliferative capacity similar to that observed in the dysplastic and neoplastic lesions. This study indicated that altered TGF-alpha expression was detectable early in the development of renal cell tumors and may be an important feature of the transformed phenotype.

On the preattentive accessibility of stereoscopic disparity: evidence from visual search

We examined the generality of the claim that stereoscopic disparity is detectable in parallel across the visual field. Using a search paradigm with random-dot stereograms, we varied the relative disparity of target and distractor items. When both target and distractors had crossed disparities, both search functions (i.e., target in front of distractors and target behind distractors) were linear with positive slopes. When both target and distractors had uncrossed disparities, the pattern of results depended upon whether the target was in front of or behind the distractors-specifically, when the target was in front of the distractors, search functions were similar to those seen for "crossed" search, but when the target was behind the distractors, a nonlinear search function was found. Finally, when the target and distractors straddled the plane of fixation, a nonlinear search function was found when the target was in front of the distractors; however, when the target was behind the distractors, a linear search function with a large positive slope was found. We show that the nonlinear search functions are consistent with the effects of an intervening global surface percept. We also show that the size of the stimulus display may be a factor in some relative depth cases. Additionally, we replicate Steinman's (1987) finding that search is parallel when the distractors are located at the plane of fixation and the target disparity is crossed, eliminating monocular and spatial cues to target presence that may have been present in his original study. In a final control experiment, we showed that reaction times did not increase with set size when observers performed another kind of perceptual task on similar random-dot stereogram displays. This eliminates the possibility that some of the results obtained here can be explained by increases in the difficulty of perceiving/fusing the stimuli when the number of distractors is increased.

Characterization of the rat neurofibromatosis 2 gene and its involvement in asbestos-induced mesothelioma

The neurofibromatosis 2 (NF2) tumor suppressor gene was recently implicated in the genesis of human mesothelioma. To investigate the role of this tumor suppressor gene in rat asbestos-induced mesothelioma, a commonly used model for the human disease, we characterized the rat homologue of NF2 and examined rat chrysotile-induced primary mesotheliomas and cell lines derived from chrysotile- and crocidolite-induced mesotheliomas for alterations in this gene. The coding sequence obtained for the rat NF2 gene had 90% nucleotide homology with the human NF2 gene. The rat NF2 gene was ubiquitously expressed as a 4.4-kb transcript in normal rat tissues as well as in rat mesothelioma cell lines. Reverse transcription-polymerase chain reaction analysis to examine splicing of NF2 exons in mesothelioma cells indicated that the exon splicing pattern was similar in normal and neoplastic cells. To determine if mutations had occurred in the NF2 coding region in rat mesotheliomas, single-strand conformation polymorphism analysis and direct sequencing were used to screen 10 primary tumors and six tumor cell lines. No DNA sequence alterations were observed in any of the rat mesothelioma samples examined. These findings contrast with data reported previously for human mesotheliomas, in which the NF2 gene was found to be mutated in 40% of cases. Taken together, these data suggest that the role of NF2 in the development of rodent asbestos-induced mesothelioma may differ significantly from the role in the human disease.

Cancer susceptibility genes and molecular carcinogenesis. American Association for Cancer Research Special Conference: Cancer Susceptibility Genes and Molecular Carcinogenesis

As elaborated by Nobel Laureate Harold Varmus (Director of the National Institutes of Health, Bethesda, MD, USA) in his Keynote address, future studies must not only continue to expand our repertoire of genetic determinants of cancer susceptibility by identifying new cancer susceptibility genes, but most also now begin to address the function of these genes and their roles in the process of tumor development. Key areas for future investigation in this field, identified at the meeting, were: (1) understanding how susceptibility genes are altered in cancer cell physiology, (2) elucidating the function of these genes in the biochemistry of cellular signaling pathways; and (3) improving our ability to use this information to extrapolate basic oncology research to the clinic. At this meeting, the fields of molecular carcinogenesis, DNA repair and human genetics were very successfully integrated. These fields have converged in the areas of cell cycle control and genetic susceptibility, and this meeting capitalized on this convergence to highlight recent progress in these areas. Key areas for future research were also emphasized, including the need to apply the rapidly emerging information from these fields towards developing novel therapeutic modalities to treat and prevent cancer.

Inhibition of hamster mesothelioma tumorigenesis by an antisense expression plasmid to the insulin-like growth factor-1 receptor

We evaluated the effect of antisense insulin-like growth factor (IGF) receptor transcripts on the proliferation and tumorigenicity in an SV40-induced, immunocompetent hamster mesothelioma model (H9A). Expression of IGF-1 and IGF-1 receptor (IGF-1R) genes was identified from H9A RNA using reverse transcription-PCR and Northern analysis. H9A cells were electroporated with inducible expression vectors (under the transcriptional control of heat shock promoter HSP70) containing a cDNA fragment corresponding to base pairs 1-309 of IGF-1R in the sense or antisense orientation to generate the respective clones A3 sense or B9 antisense. The expression vector in genomic DNA was detected with PCR analysis as a 173-bp fragment on ethidium bromide gels. The effects of the expression vectors were then evaluated in vitro under active (at 39 degrees C) or inactive (at 34 degrees C) conditions. At 39 degrees C, the B9 antisense transfectants demonstrated significantly less proliferation than A3 sense transfectants (P2 < 0.02). At 34 degrees C, cell growth of A3 sense- and B9 antisense-transfected cells was not significantly different. In vivo tumorigenicity was evaluated in hamsters inoculated with 10(5) A3 sense- or B9 antisense-transfected cells. The A3 sense clones resulted in greater numbers of tumors in vivo compared to the B9 antisense clone (P2 = 0.0001). When genomic DNA from tumors that developed in A3 sense and B9 antisense animals was analyzed for the expression vectors, a 173-bp fragment amplified from the expression vector was identified in the sense tumors but not in antisense B9 or wild-type H9A tumors, indicating a loss of the vector from the antisense clones that proliferated in vivo. The inhibitory effect of IGF-1R antisense transcripts on hamster mesothelioma demonstrated in this study by decreased growth and tumorigenicity in vitro and in vivo may have implications for the therapy of human mesothelioma.

Hereditary renal cell carcinoma in the Eker rat: a unique animal model for the study of cancer susceptibility

A class of genes, the so-called tumor suppressor genes or anti-oncogenes, was originally identified as being responsible for germ-line transmission of cancer susceptibility in humans. Tumor suppressor genes are recessive at the cellular level with respect to oncogenesis but often manifest as dominantly inherited familial cancer syndromes. This type of cancer syndrome arises in the Eker rat due to a genetic defect in the tuberous sclerosis 2 (Tsc2) gene. The Eker rat familial cancer syndrome serves as a unique animal model in which to study the molecular pathways of renal tubular epithelial carcinogenesis as well as a valuable tool for studies that examine how chemical carcinogens interact with cancer susceptibility genes.

Allelic loss at the tuberous sclerosis 2 locus in spontaneous tumors in the Eker rat

Somatic events leading to the inactivation of tumor suppressor genes often involve chromosomal alterations that can be detected as loss of heterozygosity (LOH). In the Eker rat, spontaneous tumors of the kidney, uterus, and spleen develop as a result of a germline mutation of the tuberous sclerosis 2 (Tsc2) gene. We examined the pattern and frequency of LOH at the predisposing locus in 77 primary tumors and cell lines to gain an understanding of the role of Tsc2 allelic loss in the pathogenesis of Eker-derived tumors. Although most renal and uterine tumors (primary and cell lines) displayed LOH, splenic hemangiosarcomas did not. Although the presence of normal tissue may account for some of this difference, the possibility exists that an alternative mechanism, such as subtle mutation or gene dosage effects, may be involved during splenic tumorigenesis. Northern analysis confirmed that LOH resulted in loss of the wild-type transcripts for the Tsc2 gene. Thus, the inactivation of both alleles plays an important role in renal and uterine tumor development, in keeping with Knudson's two-hit hypothesis. In addition, renal tumors that retained the wild-type allele also did not express the normal transcript, suggesting that the remaining Tsc2 alleles had acquired subtle mutations resulting in loss of gene function.

Expression of insulin-like growth factor II in spontaneously immortalized rat mesothelial and spontaneous mesothelioma cells: a potential autocrine role of insulin-like growth factor II

Insulin-like growth factors (IGFs) are polypeptides that play an important role in cellular proliferation and differentiation. The present study examines the role of IGFs in the growth of mesothelial cells. Cell lines derived from normal rat mesothelium as well as lines derived from spontaneous rat mesotheliomas were found to express RNA transcripts for IGF-II. In contrast, cell lines derived from asbestos-induced rat mesotheliomas did not express this growth factor. All cell lines expressed receptors for IGF-I and IGF-II, as well as insulin receptors. Coexpression of IGF-II and its cognate receptor suggested that IGF-II was acting as an autocrine growth factor in the spontaneously immortalized cells and the cells derived from the spontaneous tumors. The biological activity of IGF-II secreted by the cell lines into conditioned medium could be neutralized using an IGF-II-specific antibody. Growth was inhibited in a dose-dependent manner; at the highest antibody concentration used (100 micrograms anti-IGF-II/ml), cell growth was decreased to 47% of control values. This inhibition was partially reversible by treatment of the cultures with IGF-II (91% of the control). These data suggest that IGF-II expression may be involved in the spontaneous alteration of rat mesothelial cells and may function as an autocrine or paracrine growth factor to modulate the growth of these cells in vitro and in vivo. Ubiquitous expression of IGF-II by cells that have not been exposed to asbestos and the lack of IGF-II expression by asbestos-transformed cells suggest that the mechanisms of changes in growth factor expression differ in mesothelial cells transformed by different pathways.

Association of rat p15INK4B/p16INK4 deletions with monosomy 5 in kidney epithelial cell lines but not primary renal tumors

Recently the putative tumor suppressor gene p16INK4 was mapped to human chromosome 9p21, which is homologous to rat chromosome 5. Monosomy of rat chromosome 5 occurs with high frequency in rat kidney tumor-derived cell lines (ERC lines). Thus, we studied these lines in order to investigate the involvement of p15INK4B and p16INK4 in the genesis of this tumor type. p15INK4B and p16INK4 were found by Southern blot analysis to be codeleted in five of seven of these lines. This was confirmed by Northern blot analysis with a probe for the rat p15INK4B gene. In normal rat tissues, expression of p15INK4B was abundant in lung (2.5 and 2.0 kilobases), less abundant in testis (2.5, 2.0, 1.1, and 0.9 kilobases), barely detectable in liver (2.0 kilobases), and not detectable in neonatal kidney, adult kidney, brain, heart, or spleen. In the ERC lines, p15INK4B was expressed as a single 2.0-kilobase transcript observed only in those cell lines in which the gene was detected by Southern blot analysis. However, neither p15INK4B nor p16INK4 were deleted in 12 of 12 primary kidney tumors examined, suggesting that deletion of these genes is not directly involved in the process of renal tumor development but may be related to tumor progression or autonomous growth in vitro. A panel of rat kidney epithelial cell lines chemically transformed in vitro (TRKE lines) that had high-frequency monosomy 5 were also examined, but deletion of p15INK4B and p16INK4 was observed in only one of six of the TRKE lines. To our knowledge, this is the first reported investigation of these genes in rodent tumors and cell lines, and its data support the theory that alterations of genes located in the INF region of rat chromosome 5 may play a role in rodent cell transformation.

Colocalization of the rat homolog of the von Hippel Lindau (Vhl) gene and the plasma membrane Ca++ transporting ATPase isoform 2 (Atp2b2) gene to rat chromosome bands 4q41.3-->42.1

Using fluorescence in situ hybridization, we localized the rat homolog of the von Hippel-Lindau gene (Vhl) to rat chromosome band 4q41.3-->q42.1. We also mapped the gene encoding the plasma membrane Ca(++)-transporting ATPase isoform 2(Atp2b2) to the same chromosome subregion. These two genes together with Raf1 appear to be members of a large syntenic gene cluster that maps to human chromosome bands 3p25-->p26, mouse chromosome bands 6 C3-->E, and rat chromosome bands 4q41-->q42. Cytogenetic analysis of NRK 52E cells derived from immortalized normal rat kidney epithelial cells revealed an inverted duplication of the region containing this gene cluster.

Characterization of cell lines derived from formaldehyde-induced nasal tumors in rats

Cell lines derived from formaldehyde-induced nasal tumors in Fischer 344 rats were established. All of the lines were found to be epithelial and aneuploid and to express keratin, transforming growth factor-alpha, and epidermal growth factor receptor transcripts. Two of four lines were tumorigenic upon injection into nude mice, and these lines also contained point mutations in the p53 suppressor gene. The data indicate that these lines possess characteristics that make them a valuable tool for the study of chemically induced respiratory tract carcinogenesis.

Sibling bereavement and grief responses

A child's death can have a profound and lasting effect on surviving siblings. Early researchers and clinicians have suggested that siblings were at risk for serious psychopathology. However, in later studies, researchers found that although the grief process was emotionally difficult, siblings may have grown and matured as a result of living through the loss. The purpose of this report was to review and summarize the literature on sibling bereavement and grief as well as to present nursing implications.

Hospital control and decision making: a financial perspective

A study was conducted to test the hypothesis that there are no significant differences in financial decision making among hospitals in different control categories. Significant differences were found in financial decision making in for-profit hospitals, voluntary hospitals with religious affiliations, and secular voluntary hospitals. Managers of for-profit hospitals base their financial decisions more on the need to achieve operating efficiency and profitability than do managers of voluntary hospitals. Managers of voluntary hospitals with religious affiliations and secular voluntary hospitals give about the same emphasis to efficiency. Surprisingly, however, managers of voluntary hospitals with religious affiliations emphasize profitability and financial leverage more than managers of secular voluntary hospitals do.

A cross-sectional analysis of hospital profitability

This study used logit regression to discriminate between profitable and non-profitable hospitals. The specified model worked best for voluntary hospitals, and the classification results were consistently higher for profitable hospitals than for non-profitable hospitals. Only one financial variable, the operating margin, was consistently significant in each regression equation. The results challenged the "general consensus" that operating efficiency is uniform across control categories. Teaching status was found to have a significant and positive effect, but only for voluntary hospitals. Lastly, the results indicate that uncompensated care is a major concern for voluntary hospitals. These findings raise the question of whether reimbursement rates under PPS should incorporate local factors. They also indicate that hospital management style does not and will not model business operations. As such, hospital managers may be unable to dramatically change a hospital's level of profitability.

Hereditary renal cell carcinoma in the Eker rat: a rodent familial cancer syndrome

A rodent model of hereditary cancer in which a single gene mutation predisposes rats to bilateral multicentric renal cell carcinoma (RCC) is described. This rat hereditary cancer syndrome shares certain similarities with von Hippel-Lindau disease (VHLD). In addition to the early development of renal epithelial tumors with morphologic similarity to human RCC, rats which bear the RCC gene are predisposed to the development of secondary primary cancers later in life. Splenic vascular proliferative lesions, including hemangiosarcoma, were seen in 23% of 14-month-old rats of both sexes that had renal tumors. At fourteen months of age, 62% of female rats with renal cell tumors had sarcomas of the lower reproductive tract of probable smooth muscle origin. Non-carrier siblings of affected animals did not have renal, reproductive, or splenic neoplasia. The finding of a specific constellation of familial neoplasms, including multicentric bilateral renal cell carcinoma, in this autosomal dominant disorder of rats suggests that this syndrome is analogous to human VHLD. In addition to its usefulness for studies of the biochemical and molecular mechanisms of renal carcinogenesis, this animal model will provide a unique tool to investigate how cancer susceptibility genes interact with environmental risk factors such as chemical carcinogens.

Influenza vaccination: a successful outpatient program

We initiated a program to evaluate patient reasons for refusing immunization in an allergy clinic. A general medicine clinic was studied for comparison. For the Northwestern University Allergy Service (NUAS) there were five full-time salaried and seven voluntary physicians. In the general medicine clinic there was one part-time salaried physician. Four hundred eighty-eight NUAS patients and 48 general medicine patients were evaluated. Ninety-five percent of the patients agreed to vaccination. Egg allergy, the only valid contraindication to influenza vaccination, was reported by three (< 1%) patients. Transient mild symptoms consisting of fatigue, myalgias, rhinitis and/or diarrhea were reported in 20% of the patients who received vaccination. No severe systemic reactions were reported. No significant difference in the vaccination acceptance rate was noted between the subspecialty and primary care outpatient clinics. The importance of influenza immunization in patients with asthma and in other high-risk populations deserves emphasis, and high success rates are achievable when emphasized by physicians.

Arthroscopic fixation of osteochondritis dissecans. Outpatient treatment for condylar defects

According to a 1990 study, 88% of the patients assessed their postoperative result as excellent or good after two years of follow up. One disadvantage to this repair is the need for a second arthroscopy for compression screw removal; however, this allows the surgeon an opportunity to assess healing. Surgeons are continuing to advance arthroscopic surgery by using supplemental bone grafts, with or without compression screw fixation. Arthroscopic compression screw fixation of osteochondritis dissecans is a progressive alternative for patients who may otherwise have been candidates for an open-knee arthrotomy.

The Barr body is a looped X chromosome formed by telomere association

We examined Barr bodies formed by isodicentric human X chromosomes in cultured human cells and in mouse-human hybrids using confocal microscopy and DNA probes for centromere and subtelomere regions. At interphase, the two ends of these chromosomes are only a micron apart, indicating that these inactive X chromosomes are in a nonlinear configuration. Additional studies of normal X chromosomes reveal the same telomere association for the inactive X but not for the active X chromosome. This nonlinear configuration is maintained during mitosis and in a murine environment.

Hypogammaglobulinemia associated with cytomegalovirus pneumonia

Transient but profound hypogammaglobulinemia occurred during cytomegalovirus (CMV) pneumonia in a patient who developed striking declines in number of T lymphocytes. A 66-year-old, female, human immunodeficiency virus-negative patient requiring long-term hemodialysis had normal serum immunoglobulin concentrations before the onset of CMV pneumonia (IgG, 1070-1470 mg/dl; IgA, 94-102 mg/dl; IgM, 30-48 mg/dl). During the pneumonia episode, serum immunoglobulin concentrations were profoundly reduced (IgG, 440 mg/dl; IgA, 40 mg/dl; IgM, 25 mg/dl). Total lymphocytes declined from 3048/mm3 to 212/mm3 with reductions in CD4+CD45- lymphocytes (inducers of B cells) to 9% (nl, 24%-32%) and CD4+CD45+ lymphocytes (inducers of suppressor T cells) to 4% (nl, 14%-22%). CD8 lymphocytes were reduced to 5% (nl, 19%-31%). As the pneumonia resolved, serum immunoglobulin concentrations returned to normal. This is one of the few reported instances of CMV infection apparently causing hypogammaglobulinemia.

Erythema multiforme and Stevens-Johnson syndrome. Descriptive and therapeutic controversy

Diagnosis and particularly the management of erythema multiforme and Stevens-Johnson syndrome are controversial in medical textbooks and thus in individual cases. In these diseases, fatalities may result from various causes, including secondary infection or visceral organ damage to lung, liver, or kidneys. We present a series of 13 cases managed by one group of physicians which demonstrates the controversy in certain cases, and we review the controversy in the medical literature. Corticosteroid therapy used in this series was considered beneficial in every case by the managing physician and lifesaving in some cases. There were no fatalities in this series. Although the summation may be considered as our opinion only, the frequently suggested "controlled trial of corticosteroid therapy" can probably never be done for ethical reasons, and series such as this will have to establish the standard of therapy.

Problems of instrument selection

There are many problems in selecting appropriate instruments to use in research with children. Four problem areas have been outlined: instrument sensitivity, data source (adult report or observation v child self-report), adaptability to different ages and developmental levels, and the context or setting.

Siblings of children with cancer

The psychosocial concerns of siblings of children with cancer have been studied for more than 30 years. This article reviews the research and clinical literature on the major stressors affecting siblings of pediatric patients with cancer with particular focus on the coping process. The coping process includes adaptive and maladaptive coping strategies used by the children. Negative and positive sibling psychosocial responses to the diagnosis and treatment of a malignancy are detailed with suggested nursing interventions.

Prednisonephobia

The use of chronic systemic corticosteroids in allergic diseases should be restricted to cases where these agents are essential. Potentially fatal asthma and idiopathic anaphylaxis are examples of essential need for prednisone. The usual dose requirements on an alternate day regimen are often modest in these diseases, and complications of steroid therapy are minimal and are of no major concern particularly when the alternative may be a fatality. In spite of these facts, certain patients have a phobic response to the requirement for prednisone therapy. We report seven cases of prednisonephobia and classify this phobia as interpersonal, iatrogenic, bibliophilic, or parental. Some of these phobic reactions may seriously interfere with medical management or patient survival. An information sheet is included which may help certain of these patients.

T cell function and expression are dramatically altered in T cell receptor V gamma 1.1J gamma 4C gamma 4 transgenic mice

We have characterized transgenic mice carrying a functional T cell receptor (TCR) C gamma 4 (V gamma 1.1J gamma 4C gamma 4) gene. Results indicate that active transcription of the C gamma 4 transgene can influence expression of the endogenous C gamma 4, C gamma 1 (V gamma 3-, V gamma 4-, V gamma 2-, or V gamma 5J gamma 1C gamma 1) and C gamma 2 (V gamma 1.2J gamma 2C gamma 2) genes, while the ultimate expression of other TCR delta, alpha, and beta chain genes, as well as the adult T cell response, are relatively unaltered. Cells expressing transgenic C gamma 4 and endogenous delta TCR transcripts can migrate to the skin as dendritic epithelial cells (DEC) even though C gamma 4 cells are rarely, if at all, found in the skin. Transgenic and control mice were compared at 2 weeks, 6-7 weeks, and older. At 2 weeks, the thymus of transgenic mice, particularly the medulla, was much larger than control. Moreover, peripheral lymphoid tissues of younger mice were markedly (as much as 100-fold) more immunoreactive (both Con A response and alloreactivity). These differences, although persistent, became smaller in older mice. The data suggest that transgene expression has a major effect on T cell development and reactivity.

Baker's asthma: report of an unusual case

Using immunologic techniques recently available, we report the evaluation of baker's asthma due to wheat flour and demonstrate the usefulness of these techniques in occupational asthma. The diagnosis of baker's asthma was very important in this case, as even a trial of avoidance of work exposure was not possible because of the social and economic factors involved. A commercial wheat extract was obtained and the wheat flour actually used at the work site was extracted. Prick skin testing with each of these extracts resulted in positive wheal and flare responses. Enzyme linked immunosorbent assay and inhibition assays were performed to assess the worker's antibody response to wheat flour and wheat extracts. Significant specific IgE and IgG levels to the wheat flour and wheat extracts were detected in the worker's serum. Because of unique psychosocial and educational factors, this worker was unable to change occupations. Even with respiratory protection, she continued to be symptomatic. She is currently controlled on bronchodilators and inhaled steroids.

Diphenylmethane diisocyanate hypersensitivity pneumonitis: a serologic evaluation

We describe the clinical and immunologic evaluation of a steel plant maintenance supervisor who had clinical symptoms consistent with hypersensitivity pneumonitis. No antigen was obvious but after a thorough occupational history and review of the industrial hygiene data, the most likely antigen appeared to be diphenylmethane diisocyanate. Precipitating antibodies were not detected in the worker's serum; however, significant antibody levels of IgG specific for diphenylmethane diisocyanate-human serum albumin were detected by other immunoassays. This case highlights the importance of a thorough occupational history and an aggressive laboratory immunologic evaluation in identifying the offending agent in a worker with hypersensitivity pneumonitis. Hypersensitivity pneumonitis due to an inhaled reactive chemical may be present without precipitins demonstrated in vitro due to the nature of the haptenized chemical protein conjugate or the concentration of IgG antibody.