Cloning and characterization of a novel human class I histone deacetylase that functions as a transcription repressor

Histone acetylation alters chromatin state by modifying lysines on histone and plays an important role in modulating gene transcription. A dynamic balance of histone acetylation/deacetylation is maintained by histone acetyltransferases and histone deacetylases. Emerging evidence suggests that a family of histone deacetylases may exist to regulate diverse cellular functions, including chromatin structure, gene expression, cell cycle progression, and oncogenesis. We describe here a novel human histone deacetylase, named HDAC8, cloned from human kidney. HDAC8 encodes 377 amino acid residues and shares extensive homology to several known HDACs, in particular a histone deacetylase from Arabidopsis thaliana. Northern blot analyses revealed that HDAC8 expression pattern for HDAC8 is distinct from that for HDAC1 and HDAC3, and expression of HDAC8 mRNA occurs in multiple organs including heart, lung, kidney, and pancreas. HDAC8 mRNA was also observed in several cell lines derived from cancerous tissues. When expressed in HEK293 cells, HDAC8 exhibited deacetylase activity toward acetylated histone, indicating that this protein is a bona fide histone deacetylase. Its histone deacetylase activity was inhibited by trichostatin and other known histone deacetylase inhibitors. Furthermore, active recombinant HDAC8 was expressed and purified from Escherichia coli. When ectopically expressed in cells, HDAC8 was found to be localized to the nucleus. Co-transfection experiments demonstrated that expression of HDAC8 repressed a viral SV40 early promoter activity. These results indicate that HDAC8 is a novel member of the histone deacetylase family, which may play a role in the development of a broad range of tissues and potentially in the etiology of cancer.

Caltech Faint Galaxy Redshift Survey. XI. The Merger Rate to Redshift 1 from Kinematic Pairs

The rate of mass accumulation due to galaxy merging depends on the mass, density, and velocity distribution of galaxies in the near neighborhood of a host galaxy. The fractional luminosity in kinematic pairs combines all of these effects in a single estimator that is relatively insensitive to population evolution. Here we use a k-corrected and evolution-compensated volume-limited sample having an R-band absolute magnitude of Mk,eR</=-19.8+5logh mag drawing about 300 redshifts from the Caltech Faint Galaxy Redshift Survey and 3000 from the Canadian Network for Observational Cosmology field galaxy survey to measure the rate and redshift evolution of merging. The combined sample has an approximately constant comoving number and luminosity density from redshift 0.1 to 1.1 (OmegaM=0.2, OmegaLambda=0.8); hence, any merger evolution will be dominated by correlation and velocity evolution, not density evolution. We identify kinematic pairs with projected separations less than either 50 or 100 h-1 kpc and rest-frame velocity differences of less than 1000 km s-1. The fractional luminosity in pairs is modeled as fL&parl0;Deltav,rp,Mk,er&parr0;&parl0;1+z&parr0;mL, where &sqbl0;fL,mL&sqbr0; are &sqbl0;0.14+/-0.07,0+/-1.4&sqbr0; and &sqbl0;0.37+/-0.7,0.1+/-0.5&sqbr0; for rp</=50 and 100 h-1 kpc, respectively (OmegaM=0.2, OmegaLambda=0.8). The value of mL is about 0.6 larger if Lambda=0. To convert these redshift-space statistics to a merger rate, we use the data to derive a conversion factor to a physical space pair density, a merger probability, and a mean in-spiral time. The resulting mass accretion rate per galaxy (M1,M2>/=0.2M*) is 0.02+/-0.01&parl0;1+z&parr0;0.1+/-0.5M* Gyr-1. Present-day high-luminosity galaxies therefore have accreted approximately 0.15M* of their mass over the approximately 7 Gyr to redshift 1. Since merging is likely only weakly dependent on the host mass, the fractional effect, deltaM&solm0;M approximately 0.15M*&solm0;M, is dramatic for lower mass galaxies but is, on the average, effectively perturbative for galaxies above 1M*.

Overexpression of ribonucleotide reductase as a mechanism of resistance to 2,2-difluorodeoxycytidine in the human KB cancer cell line

In this study, human oropharyngeal epidermoid carcinoma KB cells that were resistant to 2,2-difluorodeoxycytidine (dFdCyd) were selected and designated the KB-Gem clone. The KB parental cell line IC50 was 0.3 microM dFdCyd, as compared with the KB-Gem clone IC50 of 32 microM dFdCyd. The KB-Gem clone demonstrated overexpression of ribonucleotide reductase (RR) M2 subunit mRNA (9-fold) and overexpression of M2 protein (2-fold); RR activity was 2.3-fold higher than the KB parental cell line. Both the dATP and dCTP pools of the KB-Gem clone increased 2-fold over the parental cell line, with no change in the dGTP and dTTP pools. Reverse transcriptase-PCR was used to clone the cDNA of deoxycytidine kinase (DCK). Resulting sequences revealed two silent mutations in the KB-Gem clone. The amino acid sequence of the DCK protein and mRNA expression remained unchanged. The KB-Gem clone's DCK enzyme activity was 56% of that of the parental cell line. After the endogenous dNTPs were removed with a G-25 column, no difference was evident between the enzyme activities of the KB-Gem clone and parental cells. Thus, contrary to previous hypotheses, DCK deficiency does not play the primary role in the resistance mechanism of dFdCyd, accepting a secondary role to the overexpression of the target gene, RR, and pool expansion.

DEF-1, a novel Src SH3 binding protein that promotes adipogenesis in fibroblastic cell lines

The Src homology 3 (SH3) motif is found in numerous signal transduction proteins involved in cellular growth and differentiation. We have purified and cloned a novel protein, DEF-1 (differentiation-enhancing factor), from bovine brain by using a Src SH3 affinity column. Ectopic expression of DEF-1 in fibroblasts resulted in the differentiation of a significant fraction of the culture into adipocytes. This phenotype appears to be related to the induction of the transcription factor peroxisome proliferator-activated receptor gamma (PPARgamma), since DEF-1 NIH 3T3 cells demonstrated augmented levels of PPARgamma mRNA and, when treated with activating PPARgamma ligands, efficient induction of differentiation. Further evidence for a role for DEF-1 in adipogenesis was provided by heightened expression of DEF-1 mRNA in adipose tissue isolated from obese and diabetes mice compared to that in tissue isolated from wild-type mice. However, DEF-1 mRNA was detected in multiple tissues, suggesting that the signal transduction pathway(s) in which DEF-1 is involved is not limited to adipogenesis. These results suggest that DEF-1 is an important component of a signal transduction process that is involved in the differentiation of fibroblasts and possibly of other types of cells.

Tissue restricted expression of two human Frzbs in preadipocytes and pancreas

Frzb is a newly discovered family of secreted glycoproteins that function to modulate signaling activity of Wnt. Frzb proteins share sequence homology with the extracellular domain of the Wnt receptor (frizzled) and are capable of binding to Wnt. Thus, Frzb functions to antagonize Wnt activity by sequestering Wnt and preventing its binding to the frizzled receptor. Since the initial identification of bovine and human Frzb, several related members of this family have been isolated from rodent and human. In this paper, we describe the cloning and expression of two human frzb homologues termed hFRP-1b and hFRP-2. These human FRPs share significant homology to mouse sFRP-1 and sFRP-2 (55 and 98% identity at amino acid level, respectively). Northern blot experiments revealed that these Frzb homologues have highly restricted tissue distribution. hFRP-1b is exclusively expressed in pancreatic tissue while high levels of hFRP-2 were found in adipose tissue. In addition, low levels of hFRP-2 were also observed in other tissues including heart, pancreas and muscle. Remarkably, FRP-2 is predominantly expressed in un-differentiated preadipocytes in both rodent and man. The expression of FRP-2 is also significantly reduced in fat pads from obese mice. Taken together, these data indicate that distinctive members of the Frzb family exhibit different expression patterns in vivo, suggesting their ability to modulate diverse aspects of Wnt signaling. The expression and dysregulation of sFRP-2 in fat and obesity also suggest a potential roles on the Wnt signaling pathway in the pathology of obesity and related metabolic diseases. Molecular cloning and expression of these Frzbs will allow detailed molecular and biochemical analysis of Wnt-Frzb interaction and their impact on Wnt-Frizzled receptor signal transduction.

Short-wave cone signal in the red-green detection mechanism

Previous work shows that the red-green (RG) detection mechanism is highly sensitive, responding to equal and opposite long-wave (L) and middle-wave (M) cone contrast signals. This mechanism mediates red-green hue judgements under many conditions. We show that the RG detection mechanism also receives a weak input from the short-wave (S) cones that supports the L signal and equally opposes M. This was demonstrated with a pedestal paradigm, in which weak S cone flicker facilitates discrimination and detection of red-green flicker. Also, a near-threshold +S cone flash facilitates detection of red flashes and inhibits green flashes, and a near-threshold -S cone flash facilitates detection of green flashes and inhibits red flashes. The S contrast weight in RG is small relative to the L and M contrast weights. However, a comparison of our results with other studies suggests that the strength of the absolute S cone contrast contribution to the RG detection mechanism is 1/4 to 1/3 the strength of the S contribution to the blue-yellow (BY) detection mechanism. Thus, the S weight in RG is a significant fraction of the S weight in BY. This has important implications for the 'cardinal' color mechanisms, for it predicts that for detection or discrimination, the mechanisms limiting performance do not lie on orthogonal M-L and S axes within the equiluminant color plane.

Peroxisome proliferator-activated receptor gamma and the control of adipogenesis

The adipose cell is now known to play a complex role in energy homeostasis, storing energy and signaling to other tissues concerning the state of energy balance. The past several years have seen an explosive increase in our knowledge of the transcriptional basis of adipocyte differentiation. This review describes the role of peroxisome proliferator-activated receptor gamma in this process, and describes how other transcription factors may affect adipogenesis by modulating the amount or activity of peroxisome proliferator-activated receptor gamma. Furthermore, peroxisome proliferator-activated receptor gamma and other adipogenic transcription factors provide a focus for beginning to understand how various hormones and metabolites influence the development of this tissue in vivo.

PPAR gamma and the control of adipogenesis

We recently cloned PPAR gamma as a factor that binds to an enhancer which has specificity for adipose cells. When expressed ectopically, PPAR gamma converts fibroblasts into bona fide preadipose cells. Upon application of activators or PPAR gamma ligands, these cells differentiate into fat cells. Most recently, we have been trying to understand the nature of natural ligands that activate PPAR gamma and the protein domains that control adipogenesis. With regards to ligands, we have shown that an unusual prostanoid, 15-deoxy delta 12,14PG J2, can bind to PPAR gamma and activate it. A second transcription factor that is induced early in differentiation, ADD1/SREBP1, appears to promote the formation of PPAR gamma ligands. Transfection of this molecule, a member of the bHLH family, causes the secretion of molecules that can serve as ligands for PPAR gamma. This ligand-like activity is specific for the gamma isoform of PPAR. Current studies are attempting to identify these potentially novel ligands. With regard to structure-function of PPAR gamma, we first analyzed the adipogenic activity of the three isoforms of PPAR: alpha, gamma and delta. Using appropriate activators of each it is clear that PPAR gamma has the most adipogenic action. PPAR alpha can be adipogenic with high levels of the strongest activators and PPAR delta does not stimulate fat cell differentiation. To identify the domain(s) of PPAR gamma responsible for differentiation, chimeras between PPAR gamma and PPAR delta were created and transfected into fibroblasts. This has allowed the isolation of relatively small regions of this molecule that are responsible for differentiation.

Inhibition of adipogenesis through MAP kinase-mediated phosphorylation of PPARgamma

Adipocyte differentiation is an important component of obesity and other metabolic diseases. This process is strongly inhibited by many mitogens and oncogenes. Several growth factors that inhibit fat cell differentiation caused mitogen-activated protein (MAP) kinase-mediated phosphorylation of the dominant adipogenic transcription factor peroxisome proliferator-activated receptor gamma (PPARgamma) and reduction of its transcriptional activity. Expression of PPARgamma with a nonphosphorylatable mutation at this site (serine-112) yielded cells with increased sensitivity to ligand-induced adipogenesis and resistance to inhibition of differentiation by mitogens. These results indicate that covalent modification of PPARgamma by serum and growth factors is a major regulator of the balance between cell growth and differentiation in the adipose cell lineage.

Adipocyte differentiation: a transcriptional regulatory cascade

The adipose cell is now known to play a complex role in energy homeostasis, energy storage and signaling to other tissues concerning the state of energy balance. The past few years have seen an explosive increase in our knowledge of the transcriptional basis of adipocyte differentiation. Factors such as peroxisome proliferator-activated receptor gamma, the CCAAT/enhancer binding protein family members, and adipocyte determination- and differentiation-dependent factor 1 play important regulatory roles in this process. Furthermore, these factors provide a focus for beginning to understand how various hormones and metabolites influence the development of adipose tissue in vivo.

Negative regulation of peroxisome proliferator-activated receptor-gamma gene expression contributes to the antiadipogenic effects of tumor necrosis factor-alpha

Recent studies indicate that a peroxisome proliferator-activated receptor, PPAR gamma, functions as an important adipocyte determination factor. In contrast, tumor necrosis factor-alpha (TNF alpha) inhibits adipogenesis, causes dedifferentiation of mature adipocytes, and reduces the expression of several adipocyte-specific genes. Here, we report that treatment of 3T3-L1 adipocytes with TNF alpha resulted in a time- and concentration-dependent decrease in PPAR gamma mRNA expression to the level detected in preadipocytes. PPAR gamma mRNA levels were reduced by 95% with 3 nM TNF alpha treatment for 24 h. Half-maximal effects were seen after 3 h treatment with 3 nM TNF alpha or with 50 pM TNF alpha (24-h exposure). Parallel reductions in PPAR gamma protein levels were also observed after treatment of 3T3-L1 adipocytes with TNF alpha. Using a ribonuclease protection assay, both alternatively spliced PPAR gamma isoforms (gamma 1 and gamma 2) were shown to be negatively regulated by TNF alpha. The down-regulation of PPAR gamma by TNF-alpha preceded the diminution in expression of other adipocyte-specific genes including CCAAT/enhancer binding protein and adipocyte fatty acid-binding protein (aP2). The effect of TNF alpha was specific for the gamma-isoform of PPARs, since the expression of PPAR delta mRNA was not affected by treatment with TNF alpha. Low level constitutive expression of PPAR gamma in 3T3-L1 adipocytes (at levels approximately 2- to 3-fold higher than in preadipocytes) partially blocked the inhibitory effect of TNF alpha on aP2 and adipsin expression. These findings support the following conclusions: 1) PPAR gamma expression is necessary for the maintenance of the adipocyte phenotype. 2) PPAR gamma, but not PPAR delta, expression is sufficient to attenuate TNF alpha-mediated effects on adipocyte phenotype. 3) Reduced PPAR gamma gene expression is likely to represent an important component of the mechanism by which TNF alpha exerts its antiadipogenic effects.

Routine use of unilateral and bilateral radial arteries for coronary artery bypass graft surgery

OBJECTIVES

This study sought to evaluate the routine use of radial artery (RA) grafts in patients undergoing coronary artery revascularization.

BACKGROUND

Previous long-term studies have documented poor patency of saphenous vein grafts compared with internal thoracic artery (ITA) grafts.

METHODS

We performed a prospective review of 175 of 249 consecutive patients.

RESULTS

Fifty-four patients had bilateral RAs harvested. Mean number (+/- SD) of grafts/patient was 3.27 +/- 0.93, with 2.76 +/- 0.97 arterial grafts; a mean of 1.53 +/- 0.68 grafts were performed with the RA. The operative mortality rate was 1.6%. No deaths were related to RA grafts, and there were no RA harvest site hematomas or infections. Transient dysesthesia 1 day to 4 weeks in duration occurred in the distribution of the lateral antebrachial cutaneous nerve in six extremities (2.6%). Elective cardiac catheterization in 60 patients at 12 weeks postoperatively demonstrated a 95.7% patency rate.

CONCLUSIONS

Because of potential benefit of long-term patency associated with arterial grafts, minimal morbidity and mortality associated with use of the RA and excellent short-term patency rates, we cautiously recommend use of one or both RAs as additional conduits to be used concomitantly with the ITA for arterial revascularization of the coronary arteries.

Regulation of PPAR gamma gene expression by nutrition and obesity in rodents

The orphan nuclear receptor, peroxisome proliferator-activated receptor (PPAR) gamma, is implicated in mediating expression of fat-specific genes and in activating the program of adipocyte differentiation. The potential for regulation of PPAR gamma gene expression in vivo is unknown. We cloned a partial mouse PPAR gamma cDNA and developed an RNase protection assay that permits simultaneous quantitation of mRNAs for both gamma l and gamma 2 isoforms encoded by the PPAR gamma gene. Probes for detection of adipocyte P2, the obese gene product, leptin, and 18S mRNAs were also employed. Both gamma l and gamma 2 mRNAs were abundantly expressed in adipose tissue. PPAR gamma 1 expression was also detected at lower levels in liver, spleen, and heart; whereas, gamma l and gamma 2 mRNA were expressed at low levels in skeletal muscle. Adipose tissue levels of gamma l and gamma 2 were not altered in two murine models of obesity (gold thioglucose and ob/ob), but were modestly increased in mice with toxigene-induced brown fat ablation uncoupling protein diphtheria toxin A mice. Fasting (12-48 h) was associated with an 80% fall in PPAR gamma 2 and a 50% fall in PPAR gamma mRNA levels in adipose tissue. Western blot analysis demonstrated a marked effect of fasting to reduce PPAR gamma protein levels in adipose tissue. Similar effects of fasting on PPAR gamma mRNAs were noted in all three models of obesity. Insulin-deficient (streptozotocin) diabetes suppressed adipose tissue gamma l and gamma 2 expression by 75% in normal mice with partial restoration during insulin treatment. Levels of adipose tissue PPAR gamma 2 mRNA were increased by 50% in normal mice exposed to a high fat diet. In obese uncoupling protein diphtheria toxin A mice, high fat feeding resulted in de novo induction of PPAR gamma 2 expression in liver. We conclude (a) PPAR gamma 2 mRNA expression is most abundant in adipocytes in normal mice, but lower level expression is seen in skeletal muscle; (b) expression of adipose tissue gamma1 or gamma2 mRNAs is increased in only one of the three models of obesity; (c) PPAR gamma 1 and gamma 2 expression is downregulated by fasting and insulin-deficient diabetes; and (d) exposure of mice to a high fat diet increases adipose tissue expression of PPAR gamma (in normal mice) and induces PPAR gamma 2 mRNA expression in liver (in obese mice). These findings demonstrate in vivo modulation of PPAR gamma mRNA levels over a fourfold range and provide an additional level of regulation for the control of adipocyte development and function.

AdipoQ is a novel adipose-specific gene dysregulated in obesity

Adipose differentiation is accompanied by changes in cellular morphology, a dramatic accumulation of intracellular lipid and activation of a specific program of gene expression. Using an mRNA differential display technique, we have isolated a novel adipose cDNA, termed adipoQ. The adipoQ cDNA encodes a polypeptide of 247 amino acids with a secretory signal sequence at the amino terminus, a collagenous region (Gly-X-Y repeats), and a globular domain. The globular domain of adipoQ shares significant homology with subunits of complement factor C1q, collagen alpha 1(X), and the brain-specific factor cerebellin. The expression of adipoQ is highly specific to adipose tissue in both mouse and rat. Expression of adipoQ is observed exclusively in mature fat cells as the stromal-vascular fraction of fat tissue does not contain adipoQ mRNA. In cultured 3T3-F442A and 3T3-L1 preadipocytes, hormone-induced differentiation dramatically increases the level of expression for adipoQ. Furthermore, the expression of adipoQ mRNA is significantly reduced in the adipose tissues from obese mice and humans. Whereas the biological function of this polypeptide is presently unknown, the tissue-specific expression of a putative secreted protein suggests that this factor may function as a novel signaling molecule for adipose tissue.

Transdifferentiation of myoblasts by the adipogenic transcription factors PPAR gamma and C/EBP alpha

Skeletal muscle and adipose tissue development often has a reciprocal relationship in vivo, particularly in myodystrophic states. We have investigated whether determined myoblasts with no inherent adipogenic potential can be induced to transdifferentiate into mature adipocytes by the ectopic expression of two adipogenic transcription factors, PPAR gamma and C/EBP alpha. When cultured under optimal conditions for muscle differentiation, murine G8 myoblasts expressing PPAR gamma and C/EBP alpha show markedly reduced levels of the myogenic basic helix-loop-helix proteins MyoD, myogenin, MRF4, and myf5 and are completely unable to differentiate into myotubes. Under conditions permissive for adipogenesis including a PPAR activator, these cells differentiate into mature adipocytes that express molecular markers characteristic of this lineage. Our results demonstrate that a developmental switch between these two related but highly specialized cell types can be controlled by the expression of key adipogenic transcription factors. These factors have an ability to inhibit myogenesis that is temporally and functionally separate from their ability to stimulate adipogenesis.

Regulation of adipocyte gene expression and differentiation by peroxisome proliferator activated receptor gamma

Peroxisome proliferator activated receptor (PPAR)gamma is an orphan member of the nuclear hormone receptor superfamily and is expressed at high levels specifically in adipose tissue. Recent data suggest that this factor is a central regulator of adipocyte gene expression and differentiation. Fibroblastic cell lines that express PPARgamma ectopically can be induced to differentiate into fat cells by a variety of lipids and lipid-like activators of PPARs, suggesting that this protein may function to link adipogenesis with systemic lipid metabolism.

PPAR gamma 2 regulates adipose expression of the phosphoenolpyruvate carboxykinase gene

Phosphoenolpyruvate carboxykinase (PEPCK) is expressed at high levels in liver, kidney, and adipose tissue. This enzyme catalyzes the rate-limiting step in hepatic and renal gluconeogenesis and adipose glyceroneogenesis. The regulatory factors important for adipose expression of the PEPCK gene are not well defined. Previous studies with transgenic mice established that the region between bp -2086 and -888 is required for expression in adipose tissue but not for expression in liver or kidney tissue. We show here that a DNA fragment containing this region can function as an enhancer and direct differentiation-dependent expression of a chloramphenicol acetyltransferase gene from a heterologous promoter in cultured 3T3-F442A preadipocytes and adipocytes. We further demonstrate that the adipocyte-specific transcription factor PPAR gamma 2, previously identified as a regulator of the adipocyte P2 enhancer, binds in a heterodimeric complex with RXR alpha to the PEPCK 5'-flanking region at two sites, termed PCK1 (bp -451 to -439) and PCK2 (bp -999 to -987). Forced expression of PPAR gamma 2 and RXR alpha activates the PEPCK enhancer in non-adipose cells. This activation is potentiated by peroxisome proliferators and fatty acids but not by 9-cis retinoic acid. Mutation of the PPAR gamma 2 binding site (PCK2) abolishes both the activity of the enhancer in adipocytes and its ability to be activated by PPAR gamma 2 and RXR alpha. These results establish a role for PPAR gamma 2 in the adipose expression of the PEPCK gene and suggest that this factor functions as a coordinate regulator of multiple adipocyte-specific genes.

Stimulation of adipogenesis in fibroblasts by PPAR gamma 2, a lipid-activated transcription factor

Peroxisome proliferator-activated receptor gamma 2 (PPAR gamma 2) is an adipocyte-specific nuclear hormone receptor that has recently been identified as a key regulator of two fat cell enhancers. Transcriptional activation by PPAR gamma 2 is potentiated by a variety of lipids and lipid-like compounds, including naturally occurring polyunsaturated fatty acids. We demonstrate here that retroviral expression of PPAR gamma 2 stimulates adipose differentiation of cultured fibroblasts. PPAR activators promote the differentiation of PPAR gamma 2-expressing cells in a dose-dependent manner. C/EBP alpha, a second transcription factor induced during adipocyte differentiation, can cooperate with PPAR gamma 2 to stimulate the adipocyte program dramatically. Our results suggest that the physiologic role of PPAR gamma 2 is to regulate development of the adipose lineage in response to endogenous lipid activators and that this factor may serve to link the process of adipocyte differentiation to systemic lipid metabolism.

Adipocyte-specific transcription factor ARF6 is a heterodimeric complex of two nuclear hormone receptors, PPAR gamma and RXR alpha

Previously, we identified a novel transcription factor, ARF6, as a key regulator of the tissue-specific adipocyte P2 (aP2) enhancer. In order to identify the proteins which comprise the adipocyte ARF6 complex, we have purified this DNA binding activity from a cultured adipocyte cell line. We have developed a system for growth and differentiation of HIB-1B brown adipocytes in suspension culture that facilitates the production of large quantities of adipocyte nuclear extract. ARF6 was purified from HIB-1B nuclear extract by a combination of conventional and sequence-specific DNA affinity chromotography. Chemical sequencing and mass spectral analysis of tryptic peptides derived from the purified polypeptides identifies the ARF6 complex as a heterodimer of the retinoid X receptor alpha (RXR alpha) and the murine peroxisome proliferator activated receptor gamma (PPAR gamma). Of the known PPAR gamma isoforms, PPAR gamma is the predominant form expressed in adipose tissue. These results suggest that PPAR gamma 2 serves a unique function among PPAR family members as an important regulator of adipocyte-specific gene expression.

Targeted disruption of the c-fos gene demonstrates c-fos-dependent and -independent pathways for gene expression stimulated by growth factors or oncogenes

The c-fos proto-oncogene is believed to play a pivotal role in transducing growth factor-mediated signals from the extracellular milieu into the nucleus. c-fos protein dimerizes with c-jun and related proteins and mediates transcription via AP-1 sites. Using c-fos-deficient mice generated through gene knockout techniques, we derived 3T3-type cell lines from primary embryonic fibroblasts. The c-fos-deficient cells grow normally under optimal culture conditions and show only a slight reduction in growth rate in low serum culture compared with control cells. They also express mRNA for most of the Fos and Jun family members at normal levels. The overall levels of AP-1 DNA binding activity are normal and several genes (c-jun, MCP1, metallothionein) known to contain functional AP-1 sites are expressed normally in the c-fos-deficient and control cells. In contrast, mRNA for the metalloproteases stromelysin (MMP-3) and type I collagenase (MMP-1), which are often induced by oncogenes and growth factors and have been implicated in tumor invasiveness, cannot be induced by epidermal growth factor or platelet-derived growth factor in c-fos-deficient cells. Transformation of mutant cells with polyoma middle T oncogene essentially restores wild-type levels of stromelysin expression, while transformation with v-src leads to only a weak induction of the metalloprotease. These results clearly demonstrate that some AP-1-dependent genes require c-fos for full expression while others do not; oncogenes may activate expression of metalloproteases via either fos-dependent or fos-independent mechanisms. These results also imply that c-fos may play an important regulatory role in the invasive behavior of malignant tumors, independent of any role this proto-oncogene might play in cell growth per se.

mPPAR gamma 2: tissue-specific regulator of an adipocyte enhancer

Previously, we have isolated and characterized an enhancer from the 5'-flanking region of the adipocyte P2 (aP2) gene that directs high-level adipocyte-specific gene expression in both cultured cells and transgenic mice. The key regulator of this enhancer is a cell type-restricted nuclear factor termed ARF6. Target sequences for ARF6 in the aP2 enhancer exhibit homology to a direct repeat of hormone response elements (HREs) spaced by one nucleotide; this motif (DR-1) has been demonstrated previously to be the preferred binding site for heterodimers of the retinoid X receptor (RXR) and the peroxisome proliferator-activated receptor (PPAR). We have cloned a novel member of the peroxisome proliferator-activated receptor family designated mPPAR gamma 2, and we demonstrate that a heterodimeric complex of mPPAR gamma 2 and RXR alpha constitute a functional ARF6 complex. Expression of mPPAR gamma 2 is induced very early during the differentiation of several cultured adipocyte cell lines and is strikingly adipose-specific in vivo. mPPAR gamma 2 and RXR alpha form heterodimers on ARF6-binding sites in vitro, and antiserum to RXR alpha specifically inhibits ARF6 activity in adipocyte nuclear extracts. Moreover, forced expression of mPPAR gamma 2 and RXR alpha activates the adipocyte-specific aP2 enhancer in cultured fibroblasts, and this activation is potentiated by peroxisome proliferators, fatty acids, and 9-cis retinoic acid. These results identify mPPAR gamma 2 as the first adipocyte-specific transcription factor and suggest mechanisms whereby fatty acids, peroxisome proliferators, 9-cis retinoic acid, and other lipids may regulate adipocyte gene expression and differentiation.

Casein kinase II from Caenorhabditis elegans. Cloning, characterization, and developmental regulation of the gene encoding the beta subunit

Complementary DNAs encoding the beta subunit of casein kinase II (CKII beta) from the nematode Caenorhabditis elegans were cloned and sequenced. The predicted beta subunit polypeptide comprises 234 amino acid residues and has a Mr of 26,452. CKII beta is not homologous with other types of proteins. In synchronously developing C. elegans the abundance of the 1.3-kilobase mRNA for CKII beta varies in parallel with the level of mRNA encoding the catalytic subunit (alpha) of CKII. Thus, the developmental expression of CKII subunits is controlled coordinately and pretranslationally. CKII beta and CKII alpha mRNAs are enriched 5-10-fold in C. elegans embryos relative to their concentrations at several other stages of nematode development. A 3.8-kilobase pair segment of C. elegans DNA that contains the CKII beta gene and an extensive 5'-flanking region was cloned and sequenced. The CKII beta gene is divided into 6 exons by introns ranging from 49 to 533 base pairs in length. The first exon encodes 88 nucleotides of 5'-untranslated mRNA. Exon 2 (72 base pairs) contains the initiator Met codon and only 5 additional codons. Exons 3-6 encode 52, 63, 64, and 49 amino acid residues, respectively. The 5' terminus of CKII beta mRNA is modified post-transcriptionally by trans-splicing with a leader sequence of 22 nucleotides. The CKII beta gene was mapped to a position on C. elegans chromosome 2 that is in close proximity to the lin-11 gene.

Distribution, antibiotic susceptibility and tolerance of bacterial isolates in culture-positive cases of endocarditis in The Netherlands

During a two-year period data were collected nationwide in The Netherlands on 438 episodes of bacterial endocarditis (BE) in 432 patients. Of the strains isolated in these patients 419 were available for analysis. Of these, 326 were isolated in native valve endocarditis (NVE) and 93 in prosthetic valve endocarditis (PVE). Viridans streptococci, staphylococci and enterococci together constituted 87% of the isolates. More than 46% of the viridans streptococci consisted of Streptococcus sanguis. Enterococcus faecalis and Staphylococcus aureus were the predominant species in the late form of PVE. The majority of the viridans streptococci and haemolytic streptococci were highly susceptible to penicillin. Five of 35 strains of coagulase negative staphylococci were resistant to methicillin. Eleven percent of a random sample of the streptococci collected were tolerant to penicillin. After repeated exposure to a concentration gradient of an appropriate beta-lactam antibiotic, this figure increased to 49%. Of the staphylococci, 5-6% of the strains were tolerant before induction and 16-20% after induction. Of the Enterococcus strains (n = 40), 12.5% showed high-level resistance to one or more aminoglycoside.

Expression of wild-type and mutated forms of the catalytic (alpha) subunit of Caenorhabditis elegans casein kinase II in Escherichia coli

A full-length Caenorhabditis elegans cDNA that encodes the alpha subunit of casein kinase II was inserted into the inducible bacterial expression vector pET3a to generate the plasmid pCK alpha. Escherichia coli DE21 lysozyme S that was transformed with pCK alpha expressed soluble, catalytically active casein kinase II alpha upon induction with isopropyl beta-D-thiogalactopyranoside. The expressed alpha subunit was purified to homogeneity with a 60% yield by chromatography on CM-Sephadex, P-11 phosphocellulose, and heparin-agarose. The Mr values estimated from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (Mr = 42,000) or calculated from hydrodynamic measurements (s20,w = 3.3 S, Stokes radius = 2.8 nm, Mr = 37,000) were similar, thereby indicating that the expressed enzyme is monomeric. The native holoenzyme and the expressed alpha subunit exhibited several similar properties including the utilization of both ATP and GTP as substrates and the susceptibility to inhibition of phosphotransferase activity by low concentrations of heparin. However, the kcat for E. coli-derived alpha was only 9% of the kcat for the native holoenzyme, and catalytic activity was not stimulated by polyamines. Recombinant casein kinase II alpha aggregates at low ionic strength, and the aggregation is partially reversible. A mutant alpha subunit in which Lys74 and Lys75 were substituted by glutamic acid residues was constructed by site-directed mutagenesis. The mutant enzyme was not inhibited by typically effective concentrations of heparin (e.g. IC50 = 0.3 micrograms/ml) because the affinity of modified recombinant casein kinase II Glu-74Glu-75 for heparin decreased approximately 70-fold. Thus, Lys74 and Lys75 are implicated in the heparin binding, inhibitory domain. The successful expression of casein kinase II alpha in E. coli will facilitate the analysis of the structural basis for functional domains in this enzyme.

Phase I toxicity and pharmacology study of trimethylcolchicinic acid in patients with advanced malignancies

A phase I study of trimethylcolchicinic acid (TMCA) given orally once daily for 5 days every 3rd week was performed in 19 patients with advanced malignancies. Myelosuppression and mucositis were the major toxicities observed. Serum TMCA levels were monitored and appear to be useful in predicting toxicities. A partial response was seen in one lymphoma patient and stabilization of disease was noted in one patient each with prostatic and ovarian cancer.

Phase I study of combination recombinant interleukin-2 and interferon gamma in patients with advanced malignancies

A phase I trial of interleukin-2 and interferon gamma combination treatment in patients with advanced malignancies was performed based on preclinical in vitro and in vivo data which demonstrated synergistic antitumor effect. The toxicities, immune parameters, and tumor responses are described. The clinical and biologic maximal tolerated doses were extrapolated from these data.

Active-specific immunotherapy for melanoma

Twenty-five patients with metastatic melanoma were treated with a therapeutic vaccine ("theraccine") consisting of allogeneic melanoma lysates and a novel adjuvant, DETOX (Ribi ImmunoChem Research, Inc, Hamilton, MT). Each patient received 200 antigenic units (20 x 10(6) tumor cell equivalents) subcutaneously on weeks 1, 2, 3, 4, and 6. Clinical responses included one complete remission, three partial remissions, and a long-term (17-month) stability. Two other patients had mixed responses, with partial remissions of numerous subcutaneous nodules. Sites of responsive disease included primarily the skin, but ileal, breast, and a liver metastasis also responded. Removal of residual lesions in patients with partial remissions, whose other lesions had disappeared during treatment, led to long disease-free survivals. The median duration of remission was 17 months, with four of the five responders alive for at least 24 months after treatment. An increase in precursors of cytolytic T cells (CTLs) correlated with clinical outcome, when complete, partial, and mixed responses and long-term stability were considered. The CTLs recognized melanoma-associated antigens on many cell lines, but not other types of tumor or normal lymphocytes. Skin-test reactivity to melanoma antigens and serum antibodies against the melanoma cells was unrelated to clinical response. Toxicity was minimal, restricted largely to minor soreness at the site of injection. Only five patients, four of whom were treated with repeated courses, developed severe granulomas. These results confirm that active-specific immunization with allogeneic lysates of melanoma administered with the adjuvant DETOX can induce immunity to melanoma, and can induce regressions of disease in a proportion of patients with metastatic disease with little toxicity.

Hemolytic anemia in a cancer patient treated with recombinant interferon-gamma

Currently, three classes of interferon are used in the treatment of malignancies. Interferon-gamma is the best studied. Bone marrow suppression as well as immune hemolytic anemia have been described. Heretofore, only bone marrow suppression has been attributed to interferon-gamma (IFN gamma). In this report, we describe a woman with lung cancer being treated with IFN gamma in whom acute hemolytic anemia occurred. Immune hemolysis did not appear to be the cause. We concluded that in addition to bone marrow suppression, hemolysis should be considered in a patient receiving IFN gamma in whom an unexplained drop in hematocrit occurs.

Casein kinase II from Caenorhabditis elegans. Properties and developmental regulation of the enzyme; cloning and sequence analyses of cDNA and the gene for the catalytic subunit

The nematode Caenorhabditis elegans provides a model system for investigating the structure, function, and regulation of casein kinase II. Cytosols from C. elegans embryos and gravid adults, which contain fertilized eggs and embryos, are enriched in casein kinase II activity; cytosols from newly hatched larva, four subsequent larval stages, and immature adults exhibit casein kinase II levels that are 3-10-fold lower than those observed in embryo cytosol. C. elegans casein kinase II contains alpha (Mr = 42,000) and beta (Mr = 29,000) subunits and has a Stokes radius of 50 nm. The enzyme utilizes ATP and GTP as substrates, is potently inhibited by heparin and undergoes autophosphorylation. Sequence analyses of cloned cDNAs corresponding to the 1.7-kilobase mRNA encoding the alpha (catalytic) subunit of casein kinase II indicate that the alpha polypeptide contains 359 amino acid residues. Variations in the abundance of casein kinase II alpha mRNA are coordinated with changes in enzyme activity during C. elegans development, indicating that alpha subunit expression is controlled at a pretranslational level. However, the magnitude of the developmentally controlled changes in phosphotransferase activity exceeded the corresponding increments in alpha subunit mRNA content. This suggests that translational and/or post-translational mechanisms also play an important role in the developmental regulation of C. elegans casein kinase II activity. The 2.9-kilobase casein kinase II alpha gene is divided into eight exons by intervening sequences ranging from 48 to 457 base pairs in length. The alpha gene promoter contains a TATA box, and a unique transcription start site has been identified. The intron/exon organization of the casein kinase II alpha gene differs markedly from the gene structure of the catalytic subunit of murine cAMP-dependent protein kinase (Chrivia, J. C., Uhler, M. D., and McKnight, G. S. (1988) J. Biol. Chem. 263, 5739-5744).

Immunogenetic analysis of bone marrow aspirates in patients with non-Hodgkin lymphomas

The immunogenetic analysis (IGA) on the staging bone marrow aspirates in 15 patients with non-Hodgkin lymphoma (NHL) is reported. We found the sensitivity of IGA and morphologic examination in detecting bone marrow involvement by malignant lymphoma to be 91% and 82%, respectively. In 11 cases there was agreement between the morphologic findings and IGA. In 8 of these 11 cases, IGA confirmed the morphologic involvement of the bone marrow by demonstrating clonal rearrangement of either the immunoglobulin heavy- and/or light-chain or the T-cell receptor beta chain (TCR) genes. In 3 of these 11 cases, morphology showed no involvement and IGA showed germline configurations for both the immunoglobulin heavy- and light-chain or the TCR genes. In 2 additional cases the techniques proved to be complementary, as involvement was detected by only 1 of the 2 procedures. In 1 of these 2 cases, IGA showed gene rearrangement while morphologic examination was negative for involvement by NHL, while in the other case, morphologic examination showed involvement by NHL, but IGA did not show gene rearrangement. IGA was also useful in determining the clonality of solitary lymphoid nodules in the 2 remaining cases when morphologic interpretation was equivocal. In the 12 cases with bone marrow involvement, the immunophenotype and immunogenotype agreed in 11 cases. In the one case in which there was a discordance between the immunophenotype and immunogenotype, the immunophenotype was incorrectly interpreted as B-cell lineage, while the immunogenotype demonstrated a T-cell lineage. IGA also demonstrated a clonal population in 1 case of T-chronic lymphocytic leukemia where other techniques could not demonstrate the clonality of the pathologic process. IGA analysis may detect bone marrow involvement in NHL which may not be detected by morphologic examination because of patchy distribution.

Acute hepatic injury after the withdrawal of immunosuppressive chemotherapy in patients with hepatitis B

Five patients with lymphoproliferative malignancies and chronic hepatitis B suffered severe acute hepatic injury after the withdrawal of multiagent chemotherapy that included high-dose corticosteroid. Four patients died of hepatic failure, three of whom received corticosteroid as treatment for the hepatic injury. We believe that the cause of this entity is massive immune-associated cytolysis of hepatitis B virus infected hepatocytes occurring after a period of immunosuppression and increased viral replication. The literature regarding this complication of chemotherapy and its pathophysiology is reviewed.

Detection of specific t(14;18) chromosomal translocations in fixed tissues

The present study was undertaken to establish the incidence of t(14;18) (q32:q21) chromosomal translocations detectable by a polymerase chain reaction (PCR) assay on fixed lymphoma biopsies. DNA samples from 113 formalin-fixed, paraffin-embedded tissue biopsies (non-Hodgkin's lymphomas, 96 cases; Hodgkin's disease, six cases; reactive, 11 cases) were amplified by the PCR. Of the 96 non-Hodgkin's lymphoma cases, 56 had a follicular pattern and 40 had a diffuse pattern. Polymerase chain reaction-amplifiable t(14;18) chromosomal translocations were detected in 23 of 43 follicular low-grade lymphomas, one of eight follicular intermediate grade lymphomas, one of five follicular high-grade lymphomas, and one of 10 diffuse large-cell lymphomas. The remaining 30 diffuse lymphomas represented the spectrum of the Working Formulation classification. There were six biopsy specimens of Hodgkin's disease and 11 biopsy specimens of follicular hyperplasia; all were negative. The translocation was not detected in 16 biopsies (non-Hodgkin's lymphomas, seven cases; follicular hyperplasia, nine cases) from patients infected with the human immunodeficiency virus. Since this procedure uses the widely available fixed paraffin-embedded material, correlative studies between histology and genetic aberrations can be readily undertaken.

Detection of occult CNS involvement of follicular small cleaved lymphoma by the polymerase chain reaction

A patient with follicular small cleaved lymphoma presented with an unusual clinical relapse in the central nervous system (CNS) without morphologic evidence of lymphoma cells in the cerebral spinal fluid (CSF). Molecular genetic analysis of the small number of cells in the CSF after in vitro DNA amplification by the polymerase chain reaction demonstrated the presence of an abnormal translocation sequence between chromosomes 14 and 18. A similar translocation could be detected from the original fixed archival lymph node biopsy and from a small proportion of circulating mononuclear cells. These results indicated that occult lymphoma cells were present in the CSF and peripheral blood. Secondary CNS lymphoma involvement was identified at autopsy. This case demonstrates the enhanced sensitivity of lymphoma diagnosis from poorly cellular specimens after in vitro DNA amplification.

Synergistic antitumor effects of interleukin 2 and the monoclonal Lym-1 against human Burkitt lymphoma cells in vitro and in vivo

Interleukin 2 (IL-2) regulates immune responses by inducing proliferation and differentiation of T-cells into cytotoxic cells, inducing lymphokine activated killer activity and enhancing antibody dependent cellular cytotoxicity (ADCC). Lym-1, a monoclonal antibody, recognizes a membrane antigen present on the surface of B-lymphoma cells and can be used for ADCC. We therefore used Raji (human Burkitt lymphoma) cells to study the efficacy of combination therapy with IL-2, lymphokine activated killer activity, and Lym-1. In vitro ADCC assays using Lym-1 showed that preincubation of peripheral blood lymphocytes with IL-2 had a synergistic antitumor effect. The maximum synergism was achieved when peripheral blood lymphocytes were incubated with IL-2 for 3 days as compared to 1 or 2 days, with the optimal concentration of IL-2 being 1000 units/ml. This effect was specific for Lym-1 as demonstrated by experiments using an irrelevant (antimelanoma) monoclonal antibody or an irrelevant target cell (A375). The ADCC was blocked by an anti-Fe receptor antibody (3G8). In vivo experiments performed by growing Raji tumors in nude mice also demonstrated the increase in ADCC and the synergism between IL-2 and Lym-1 in terms of decreased tumor size and growth. The mechanism of this synergy is probably from activation of cells mediating ADCC. This raises the possibility that treatment of patients with low doses of IL-2 in combination with Lym-1 may enhance immune responses and thereby antitumor activity.

Detection of clonal T-cell receptor gene rearrangements in the peripheral blood of patients with mycosis fungoides/Sezary syndrome

Involvement of the peripheral blood in mycosis fungoides/Sezary syndrome (MF/SS) has a significant impact upon prognosis, but it is often difficult to distinguish circulating cells of MF/SS from atypical reactive lymphocytes. We compared the standard morphologic method of identifying leukemic cells, the Sezary preparation, to a genotypic method using Southern blot analysis of T-cell receptor gene rearrangements in concurrent blood samples. We studied 26 MF/SS patients, five of them in remission, together with five controls from cases of various non-MF/SS skin diseases. Six of 26 MF/SS patients had morphologically atypical circulating leukocytes (3%, 4%, 5%, 14%, 16%, 19%). Seven of 26 MF/SS patients had clonal T-cell receptor gene rearrangements, including the four patients with the greatest percentages of atypical cells and three patients lacking atypical cells. Six of seven patients had skin disease at the time of sampling, including three with erythroderma, two with generalized thick plaques, and one with generalized patches, while one patient was in clinical remission. All five controls lacked morphologic and genotypic evidence of atypical or clonal T-cells. Relative to genotyping, in our series the Sezary preparation was less sensitive and less specific. There were three apparent false negative results in the Sezary preparations, and two potential false positive (patients with 3% and 4% atypical leukocytes); however, there was agreement between the two techniques in most cases. We conclude that gene rearrangement studies may provide an effective test with which to assess the peripheral blood of MF/SS patients.

A phase 1a clinical trial of LYM-1 monoclonal antibody serotherapy in patients with refractory B cell malignancies

Ten patients with refractory B cell lymphomas were treated with weekly intravenous infusions of escalating doses of murine monoclonal antibody (MoAb) LYM-1 over four weeks. LYM-1 is a recently developed IgG2a murine MoAb that recognizes a polymorphic HLA-Dr antigen on surfaces of normal and malignant B cells but does not bind to any other normal tissues. MoAb LYM-1 has several advantages for serotherapy, since the antigen it recognizes is not shed from the cell surface and does not modulate in response to MoAb therapy. Furthermore, in vitro studies have indicated significant anti-tumour activity against lymphoma cell lines. In the current trial, dose-dependent levels of free LYM-1 were detected in the serum of all patients, but penetration of extravascular tumour tissues was poor. No significant toxicity or human anti-mouse antibody responses were observed in any patient. Clinical responses were minor and appeared to correlate with the number of infiltrating T cells seen in the initial lymphoma specimens. LYM-1 appears to be well-tolerated and has demonstrated several potential advantages as a therapeutic agent in patients with lymphoma. The mechanism of anti-tumour effect and plans for further clinical studies are discussed.

Third-World Hodgkin's disease at Los Angeles County-University of Southern California Medical Center

The reported experience with Hodgkin's disease (HD) in the United States has come primarily from large referral centers that attract a predominantly white population of high socioeconomic status (SES). The majority of these patients had the nodular sclerosis (NS) histologic subtype and asymptomatic stage I/II disease. We have reviewed the records of 178 patients with HD seen within the past 17 years at Los Angeles County-University of Southern California Medical Center (LAC/USC), which is a nonreferral, government-operated facility. Our patient population was found to be heterogeneous, with 38% white, 22% black, and 36% Hispanic. Systemic "B" symptoms were noted in 62% of patients at diagnosis, and 63% had advanced disease (stage III or IV). NS pathologic subtype was present in only 52% of the group. Comparison between the races revealed: (1) Hispanics had a higher incidence of lymphocyte depleted subtype and less NS than whites (P less than .06); (2) whites had equal distribution between stages I/II and III/IV; (3) blacks and Hispanics presented more frequently with stage III/IV (P = .10); and (4) extranodal involvement occurred most often in bone in whites, and was equally distributed between liver, lung, and bone in blacks and Hispanics. We conclude that the lower SES, mixed racial population seen at our institution more closely resembles the reports of HD in Third-World countries and is characterized by advanced symptomatic disease. Further, the clinical pathologic characteristics of HD in the United States may vary significantly, depending upon the precise ethnic and socioeconomic status of the patients being served.

Combined modality therapy of locally advanced breast cancer. One institution's experience and a review of the literature

Fourteen patients with locally advanced breast cancer were treated at Stanford University Medical Center with a combined modality approach. Treatment consisted of an initial 5 day course of cyclophosphamide followed by three cycles of combination chemotherapy (CAF or CMF). Patients subsequently received radiation therapy to the involved breast and regional nodal areas, followed by mastectomy if resistant disease was present following irradiation. Additional chemotherapy (CMF) was administered for 6 cycles. With a median follow up of 42 months, all fourteen patients are free of local disease. Five out of the fourteen patients have experienced distant relapses and two patients died. We conclude that an aggressive combined modality approach to treatment of locally advanced breast cancer can result in excellent local control and survival even in poor prognosis patients. A review of pertinent studies on multimodality treatment for locally advanced breast cancer confirms our findings.

Non-Hodgkin's lymphoma containing both B and T cell clones

We describe a patient in whom two lymph node biopsies removed 18 months apart disclosed histologic and immunophenotypic evidence of a non-Hodgkin's lymphoma containing neoplastic lymphocytes of both B and T type. Analyses of immunoglobulin and T cell receptor genes confirmed the presence of separate B and T cell clones. In addition, immunogenotyping revealed the possibility of a second B cell clone within the patient's tumor. Development of a multiclonal lymphoma in this patient may relate to the carcinogenic effects of chemotherapy or to a predisposition for neoplastic transformation of lymphocytes due to a previously diagnosed autoimmune condition. Another possible explanation is that the lymphoma implies the existence in this patient of a transformed lymphocyte-committed stem cell that is capable of generating both B and T lineage clones.

Phase I study of recombinant human interferon beta in patients with advanced cancer

Twenty-two patients with advanced cancer were entered into a phase I study of recombinant human interferon beta (IFN-beta). The maximum tolerated dose was 100 X 10(6) IU administered intravenously on a three times weekly schedule, and persistent fever was the dose-limiting toxicity. The majority of patients tolerated administration of IFN-beta well with negligible hematologic toxicity. Details of the clinical effects of escalating doses of recombinant human IFN-beta, administered three times weekly, are described.

Immunoglobulin gene rearrangements in Hodgkin's disease

An initial survey of biopsy specimens from 16 cases of Hodgkin's disease revealed clonal immunoglobulin gene rearrangements in one specimen, which contained large numbers of Reed-Sternberg (R-S) cells. As a result of this finding, the configuration of immunoglobulin and T-cell receptor gene DNA was investigated in biopsy tissues from other cases that were histologically and immunophenotypically consistent with Hodgkin's disease and contained numerous R-S cells. In six of seven such specimens (all of the nodular sclerosing subtype), selected solely on the basis of high R-S cell content and sufficient frozen tissue for study, at least one immunoglobulin gene was found to be rearranged in a clonal manner. Additionally, tissue samples obtained at two different time points from the original patient who showed immunoglobulin gene rearrangements revealed identical patterns of rearrangement. In the majority of cases, only a single gene showed rearrangement, and the rearranged bands in Southern blot autoradiograms were usually considerably less intense than the germline bands. No rearrangements of T-cell receptor DNA were detected in any case with a probe for the beta T-cell receptor gene. The results suggest that clonal cell populations possessing uniform immunoglobulin gene rearrangements are present in tissue in some cases of Hodgkin's disease. It is not possible to determine which cells contain these rearranged genes, but the increased incidence of detectable rearrangements in cases with high numbers of R-S cell raises the possibility that immunoglobulin gene rearrangement occurs in these cells.

Chemotherapy of malignant thymoma. Case report and review of the literature

The authors report the case of a patient with malignant thymoma unresponsive to combination chemotherapy (cyclophosphamide, doxorubicin, vincristine, and prednisone [CHOP] and cisplatin/VP-16) who subsequently achieved clinical response to continuous daily prednisone. A review of the literature indicates that prednisone and cisplatin are the most active agents in the treatment of malignant thymoma.

Diagnosis of B cell lymphoma by analysis of immunoglobulin gene rearrangements in biopsy specimens obtained by fine needle aspiration

Histologic diagnosis of lymphoma is far more difficult in the disaggregated cells obtained by percutaneous aspiration of lymph nodes than in tissue sections prepared from excisional biopsy specimens. However, the simplicity, economy, and safety of aspiration biopsy makes this an attractive diagnostic option in certain situations. In the present study, we demonstrate that lymph node aspirates provide material that is both suitable and sufficient for accurately detecting clonal proliferations of B cells by analysis of immunoglobulin gene rearrangements. The rearrangements detected in aspirated tissue serve as clonal markers that can be directly compared with the rearrangements found in histologically confirmed lymphoma removed by open biopsy. The application of gene rearrangements to aspirated material therefore offers a useful method of diagnosing lymphoma, particularly for the purposes of more thorough staging at initial presentation or the evaluation of tissues for possible relapse.

Detection of B-cell lymphoma in peripheral blood by DNA hybridisation

As an alternative to morphological identification of circulating neoplastic lymphocytes in the blood of patients with non-Hodgkin's lymphoma, DNA of peripheral blood lymphocytes was analysed for clonal immunoglobulin gene rearrangements in 29 patients with low-grade B-cell lymphomas. 76% of the patients showed clonal rearrangements of immunoglobulin genes in their blood, including 58% of those with no other evidence of disease. In seven patients from whom paired samples were available the rearranged bands found in the blood and in lymph-node biopsy specimens containing histologically confirmed lymphoma were identical. Detection of circulating lymphoma cells by use of tumour-specific anti-idiotype antibodies and cytofluorimetry showed complete agreement with the results of DNA analysis.