Marked synergism of cytotoxic agents with either a prenylation inhibitor or M-TOR inhibitor in acute leukemia cell lines: Potential clinical implications

13103

Background: The most combinations of anticancer drugs are based upon empiricism. The potential permutations of drugs overwhelm the clinical trials system. Acute leukemia is sensitive to a variety of agents but relapses are common. Targeted agents are attractive new venues of therapy both as single agents and in combination with older agents. Isobologram median effect analysis allows up to three agents to be studied together in vitro to identify interesting combinations. We evaluated a commercially available statin, fluvastatin, to block prenylation which affects a variety of pathways, rapamycin and its experimental analogue RAD001 as M-TOR inhibitors to block downstream of the AKT pathway, and cytotoxic agents. Methods: The human leukemia cell lines AML-193 and KG-1 were obtained from ATTC (Rockville, MD), fluvastatin and RAD001 from Novartis Pharma, and the other agents from Sigma-Aldrich (St. Louis, MO). The IC50 of the single agent was determined by a 72 hr incubation of log growth cells using a MTT assay and the EZ-ED50 program (Perrella Scientific, Conyers, CA). The dosages of all agents were at clinically achievable concentrations. All reported values were the means of at least 3 experiments with each study using 4 wells per point. For isobologram analysis, a minimum of 8 concentrations of drug mixtures were studied above and below the IC50. Median effect CI values less than 1 are synergistic. Results: Doublets of fluvastatin with Ara-C (0.7), daunomycin (0.4), idarubicin (0.7), RAD001 (0.5), or rapamycin (0.3) demonstrated synergy. Doublets of RAD001 with Ara-C (0.3), daunomycin (0.7), or idarubicin (0.5) demonstrated synergy. Triplets of RAD001/daunorubicin/Ara-C, RAD001/daunomycin/fluvastatin, and RAD001/Ara-C/idarubicin all demonstrated marked synergy in both cell lines. Conclusion: A new potential non classical combination for further investigation is RAD001 or rapamycin with an inhibitor of prenylation such as fluvastatin. Additional potential combinations include cytotoxics with either fluvastatin or RAD001, and triplet combinations.

No significant financial relationships to disclose.

Fluorophore-assisted carbohydrate electrophoresis (FACE) of glycosaminoglycans

OBJECTIVE

Quantitation and analyses of the fine structure of glycosaminoglycans are increasingly important for understanding many biological processes, including those most critical for understanding skeletal biology. We have developed a novel procedure, fluorophore-assisted carbohydrate electrophoresis (FACE), for determination of glycosaminoglycan fine structure and estimation of chain length.

DESIGN

FACE utilizes enzymes that cleave glycosaminoglycans to create products, usually disaccharides, characteristic of the enzyme specificity. Each cleavage exposes a new reducing terminus that is fluorotagged by reductive amination with 2-aminoacridone. The tagged products are then displayed by electrophoresis, identified by their characteristic migration and chemistry, and quantitated by their molar fluorescence.

RESULTS

Each class of glycosaminoglycan and the enzymes specific for each class are discussed. Specific application of the FACE technology is shown for analysis of the glycosaminoglycans on aggrecan isolated from knee cartilage of 5- and 68-year-old patients, and assessment of hyaluronan oligosaccharides.

CONCLUSIONS

The FACE technology is a powerful tool for analysis of all four classes of glycosaminoglycans obtained from a wide variety of biologic sources. While the FACE protocols are relative simple, they provide a wealth of information including quantitation in the pmole range, determination of fine structure, and estimation of chain length.

Novel methods for the preparation and characterization of hyaluronan oligosaccharides of defined length

Hyaluronan is a ubiquitous glycosaminoglycan of high molecular weight that acts as a structural component of extracellular matrices and mediates cell adhesion. There have been numerous recent reports that fragments of hyaluronan have different properties compared to the intact molecule. Though many of these results may be genuine, it is possible that some activities are due to minor components in the preparations used. Therefore, it is important that well-characterized and highly purified oligosaccharides are used in cell biological and structural studies so that erroneous results are avoided. We present methods for the purification of hyaluronan oligomers of defined size using size exclusion and anion-exchange chromatography following digestion of hyaluronan with testicular hyaluronidase. These preparations were characterized by a combination of electrospray ionization mass spectrometry, matrix-assisted laser desorption/ionization mass spectrometry with time-of-flight analysis, and fluorophore-assisted carbohydrate electrophoresis. Hyaluronan oligomers ranging from tetrasaccharides to 34-mers were separated. The 4- to 16-mers were shown to be homogeneous with regard to length but did contain varying amounts of chondroitin sulfate. This contaminant could have been minimized if digestion had been performed with medical-grade hyaluronan rather than the relatively impure starting material used here. The 18- to 34-mer preparations were mixtures of oligosaccharides of different lengths (e.g., the latter contained 87% 34-mer, 10% 32-mer, and 3% 30-mer) but were free of detectable chondroitin sulfate. In addition to oligomers with even numbers of sugar rings, novel 5- and 7-mers with terminal glucuronic acid residues were identified.

Relationship of early carotid artery disease with lipoprotein (a), apolipoprotein B, and fibrinogen in asymptomatic essential hypertensive patients and normotensive subjects

BACKGROUND

We investigated the relationships between plasma lipids and lipoprotein fractions and carotid artery lesions (CAL) in 177 cerebro-vascularly asymptomatic subjects, of whom 107 were primary hypertensive patients and 70 normotensive controls.

METHODS

The prevalence and severity of CAL, as assessed by calculating a score of severity (score of CAL) and the maximal stenosis of both sides, as well as the intimal-medial thickness (IMT) were evaluated with a high-resolution echo-Doppler technique. We measured total serum cholesterol, triglycerides, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, lipoprotein (a) [Lp(a)], Apo (apolipoprotein)AI, ApoAII, ApoB, and fibrinogen.

RESULTS

Both the prevalence (59.4% vs 26.2%) and severity of sex- and age-adjusted and unadjusted CAL and IMT were significantly higher in hypertensive patients than in controls. Regression analysis showed different predictors of IMT and maximal stenosis. The variables that remained in the model were age, mean blood pressure (BP), and smoking for IMT; pulse pressure, known duration of hypertension (HT), fibrinogen, and ApoB for the score of CAL; and the last four variables along with age and mean BP for maximal stenosis. Furthermore, we identified a link between the atherogenic lipoprotein fractions Lp(a) and ApoB, fibrinogen and early carotid artery atherosclerotic changes.

CONCLUSIONS

The different correlates of IMT, CAL, and maximal degree of stenosis suggest that they reflect different events occurring in the arterial wall in response to aging, HT, and other risk factors, rather than simply different stages of the same atherosclerotic process.

In vitro effects of dexrazoxane (Zinecard) and classical acute leukemia therapy: time to consider expanded clinical trials?

Anthracyclines have been the backbone of acute leukemia therapy in the adult for many years, but little attention has been paid to the long-term toxicity of these agents in this disease because of the poor survival of this population of patients. Recent studies have examined dose-intensified daunorubicin with dosages as high as 95 mg/m2 daily x 3 in this population with the attendant concerns of both acute and chronic toxicity. We have examined three human leukemia cell lines in vitro, treated with either daunorubicin, mitoxantrone, with or without cytosine arabinoside in the presence of dexrazoxane to determine whether such treatment would be synergistic or antagonistic. AML-193, CRF-SB, and Molt-4 cell lines were grown to confluence, plated into microtiter dishes and incubated for 72 h with varying concentrations of the above drugs. Cytotoxicity was determined by the MTT assay, and synergy or antagonism by median effect analysis. Dexrazoxane demonstrated additive or synergistic cytotoxic effects (CI <1) under most conditions. The triplet of daunorubicin, cytosine arabinoside, and dexrazoxane showed profound synergy in all three cell lines. These effects occurred at clinically achievable levels. If high dosages of anthracyclines are contemplated in this population, these preclinical data suggest that the addition of dexrazoxane to classical therapy is not antagonistic and thus may allow an investigation of the role of dexrazoxane as a cardiac protectant.

Myxomatous mitral valve chordae. II: Selective elevation of glycosaminoglycan content

BACKGROUND AND AIM OF THE STUDY

Chordal rupture in myxomatous mitral valves is the leading cause of leaflet prolapse and regurgitation. Increased glycosaminoglycan (GAG) content has been reported in these valves. Therefore, the biochemical differences between myxomatous and control mitral valve chordae were investigated.

METHODS

The contents of hexuronic acid, DNA, water, and collagen in chordae from 45 myxomatous valves and 10 control valves were measured. Collagen and hexuronic acid quantities were normalized to wet and dry weights, and to DNA content. Different GAG classes were measured using fluorophore-assisted carbohydrate electrophoresis (FACE).

RESULTS

Myxomatous chordae contained significantly more GAGs than controls after quantities were normalized for wet weight, dry weight, and DNA content. The FACE assay showed that the myxomatous chordae contained significantly more chondroitin/dermatan 6-sulfate when normalized to both wet and dry weight, and slightly more hyaluronan. In contrast to leaflets, which contain predominantly hyaluronan, the predominant GAG class in chordae was chondroitin/dermatan sulfate. Keratan sulfate, a GAG class previously unreported in valve tissues, was also discovered in the chordae. Myxomatous chordae contained more water and less collagen than control chordae, but equal quantities of DNA when normalized for wet weight.

CONCLUSION

Cells in the chordae of myxomatous valves may produce more GAGs than cells in the chordae of control valves. The resulting accumulation of GAGs and bound water likely gives myxomatous valves their characteristic thickening and floppy, gelatinous nature, and may account for their reported mechanical weaknesses.

A reexamination of PSC 833 (Valspodar) as a cytotoxic agent and in combination with anticancer agents

BACKGROUND

The cyclosporins have been thought as being mainly immunosuppressive agents which interfere with the function of the MDR pump and thus play a role in resistance to drug anticancer effects. We reexamined their cytotoxicity in defined cell lines both as single agents and in combination with agents which may be of value in human malignant disease.

METHODS

Cells were grown to confluence following inoculation at 5,000-8,000 cells/well in 96-well dishes, and growth patterns and death were determined by an MTT assay. Median effect analysis was used to look for synergy, additive effects, or antagonism between the cyclosporins and drugs with antitumor effects in humans.

RESULTS

Cyclosporin A and PSC 833 were found to have cytotoxic activity at clinically achievable concentrations in breast, leukemia, and prostate cell lines. Synergistic or additive effects were demonstrated in all three prostate cell lines when PSC 833 was combined with estramustine, etoposide, ketoconazole, suramin, or vinorelbine in the prostate cancer cell lines. Cell line-selective additive effects or synergism were also identified with bicalutamide, carboplatin, cisplatinum, cis-retinoic acid, dexamethasone, 5-fluorouracil, liarozole, and trans-retinoic acid.

CONLCLUSIONS

PSC 833 or cyclosporin alone or in combination with other agents may have an anticancer effect independently of their modulatory action on MDR. Several of the synergistic combinations which are not mediated by the MDR pump need to be tested in vivo for efficacy.

Synergism of cytotoxic effects of vinorelbine and paclitaxel in vitro

Empiric combinations of vinca alkaloids with taxanes have been recently used in clinical oncology. To enhance the activity of these two classes of agents, we evaluated the sequence and duration of exposure, looking for synergistic effects. Cell lines DU 145, PC 3, LnCaP, LL 86, MCF7wt, and MCF7/ADR (NCI/ADR-RES) were incubated with varying concentrations of paclitaxel or vinorelbine. Cytotoxicity was evaluated by a semiautomated MTT (3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide) method. Synergism or antagonism of these two agents either sequentially or in combination was determined by median effect analysis. Prolonged exposure of cells to either drug enhanced cytotoxic effect. Synergism or antagonism with vinorelbine and paclitaxel were both sequence dependent and cell line specific. In the case of MCF7wt, synergism was seen when a 48-hr exposure to vinorelbine preceded paclitaxel, whereas antagonism was noted when both agents were applied simultaneously or when the sequence was reversed. Concurrent vinorelbine and paclitaxel were synergistic in four of six cell lines when the exposure was extended to 96 hr but not for shorter durations of exposure. Sequential exposure of vinorelbine preceding paclitaxel or prolonged exposure to both agents concurrently needs to be tested clinically to determine whether the antitumor activity of this combination can be enhanced. In addition, these studies suggest concurrent administration of these two agents may lead to a less than optimal cytotoxic result.

Glycosaminoglycan synthesis and secretion by the retinal pigment epithelium: polarized delivery of hyaluronan from the apical surface

Hyaluronan and chondroitin sulfate glycosaminoglycan secretion from retinal pigment epithelial cells was established in confluent cultures with high transepithelial resistance. Cell cultures were maintained on Millicell-PCF culture plates, which allow separation of culture medium exposed to apical and basal epithelial surfaces. Following various times in culture, apical and basal culture media were sampled at three day intervals and the glycosaminoglycan content was quantified. Samples were digested with proteinase K to free the glycosaminoglycans from their core proteins, the glycosaminoglycans were ethanol precipitated, and subjected to hyaluronidase SD and chondroitinase ABC digestion to release hyaluronan and chondroitin sulfate disaccharides. Disaccharides were fluorotagged with 2-aminoacridone, separated on polyacrylamide gels and the molar fluorescence in each disaccharide band quantitated. Hyaluronan in the apical medium was significantly higher than in the basal medium (5-12 times) at all recovery intervals (P&lt;0.0001). In contrast, the distribution of unsulfated chondroitin, 4-sulfated chondroitin and 6-sulfated chondroitin disaccharides in apical and basal media was non-polar. Confocal microscopy of cultures probed with a hyaluronan-specific fluorotag established that the HA evident in these cultures is restricted to the apical border of the RPE cultures. Collectively, these data indicate that hyaluronan synthesized by the retinal pigment epithelium is secreted preferentially from the apical surface, suggesting that this tissue is an important source of hyaluronan present in the interphotoreceptor matrix.

Supramolecular structure of a new family of circular proteoglycans mediating cell adhesion in sponges

Aggregationfactors are the molecules responsible for species-specific cell adhesion in sponges. Here, we present the structure of the aggregation factor from the marine sponge Microciona prolifera, which constitutes the first description of a circular proteoglycan. We have analyzed chemically dissociated and enzymatically digested aggregation factor with atomic force microscopy, agarose gel electrophoresis, and Western blots using antibodies against the protein and carbohydrate moieties. Twenty units from each of two N-glycosylated proteins, MAFp3 and MAFp4, form the central ring and radiating arms, respectively, stabilized by a hyaluronidase-sensitive component. MAFp3 carries a 200-kDa glycan involved in homologous self-interactions between aggregation factor molecules, whereas MAFp4 carries a 6-kDa glycan that binds cell surface receptors. A 68-kDa lectin found in cell membranes of several sponge species binds the aggregation factor and its protein-free glycans, as well as chondroitin sulfate and hyaluronan. Here, we show that despite their lack of clear sequence homologies with other known proteoglycan structures, the protein and carbohydrate components of sponge aggregation factors assemble to form a supramolecular complex remarkably similar to classical proteoglycans.

Rab6c, a new member of the rab gene family, is involved in drug resistance in MCF7/AdrR cells

A new Rab6 homolog cDNA, Rab6c, was discovered by a hypermethylated DNA fragment probe that was isolated from a human multidrug resistant (MDR) breast cancer cell line, MCF7/AdrR, by the methylation sensitive-representational difference analysis (MS-RDA) technique. Rab6c was found to be under-expressed in MCF7/AdrR and MES-SA/Dx5 (a human MDR uterine sarcoma cell line) compared with their non-MDR parental cell lines. MCF7/AdrR cells expressing the exogenous Rab6c exhibited less resistance to several anti-cancer drugs, such as doxorubicin (DOX), taxol, vinblastine, and vincristine, than the control cells containing the empty vector. Flow cytometry experiments confirmed that the transfectants' diminished resistance to DOX was caused by increased drug accumulation induced by the exogenous Rab6c. These results indicate that Rab6c is involved in drug resistance in MCF7/AdrR cells.

Disruption of hyaluronan synthase-2 abrogates normal cardiac morphogenesis and hyaluronan-mediated transformation of epithelium to mesenchyme

We identified hyaluronan synthase-2 (Has2) as a likely source of hyaluronan (HA) during embryonic development, and we used gene targeting to study its function in vivo. Has2(-/-) embryos lack HA, exhibit severe cardiac and vascular abnormalities, and die during midgestation (E9.5-10). Heart explants from Has2(-/-) embryos lack the characteristic transformation of cardiac endothelial cells into mesenchyme, an essential developmental event that depends on receptor-mediated intracellular signaling. This defect is reproduced by expression of a dominant-negative Ras in wild-type heart explants, and is reversed in Has2(-/-) explants by gene rescue, by administering exogenous HA, or by expressing activated Ras. Conversely, transformation in Has2(-/-) explants mediated by exogenous HA is inhibited by dominant-negative Ras. Collectively, our results demonstrate the importance of HA in mammalian embryogenesis and the pivotal role of Has2 during mammalian development. They also reveal a previously unrecognized pathway for cell migration and invasion that is HA-dependent and involves Ras activation.

Adaptation of FACE methodology for microanalysis of total hyaluronan and chondroitin sulfate composition from cartilage

Protocols for analyzing the fine structure of hyaluronan and chondroitin sulfate using fluorophore-assisted carbohydrate electrophoresis of 2-aminoacridone-derivatized hyaluronidase/chondroitinase digestion products were adapted for direct analysis of previously characterized cartilage-derived samples. The chondroitin sulfate disaccharide compositions for fetal and 68 year human aggrecan from FACE analyses were DeltaDi4S (50%), DeltaDi6S (43%), and DeltaDi0S (7%); and DeltaDi4S (3%), DeltaDi6S (96%), and DeltaDi0S (1%), respectively. The nonreducing terminal structures included predominantly 4S-galNAc with minor amounts of 6S-galNAc and Di6S for the fetal aggrecan sample and, in addition, included 4,6S-galNAc in the 68 year aggrecan sample. FACE analysis of a proteinase K digest of rat chondrosarcoma tissue gave an internal disaccharide composition for its chondroitin sulfate chains of DeltaDi0S (7%) and DeltaDi4S (93%) with no DeltaDi6S and DeltaDi4, 6S detected, while DeltaDiHA from hyaluronan was 5% of the total. Analysis of nonreducing terminal structures indicated the presence of 4S-galNAc (51%), galNAc (27%), and Di4S (22%) with no 4,6S-galNAc or Di6S detected. Unexpectedly, FACE analysis detected putative linkage oligosaccharide structures from the chondroitin sulfate chains including both unsulfated (85%) and 4-sulfated (15%) linkage oligosaccharides. Finally, the number averaged chain length estimated from the ratio of the molar fluorescence of the Deltadisaccharides to that of the nonreducing termini or the linkage oligosaccharide structures was calculated as approximately 16 kDa. A tissue glucose concentration of 0.72 g/l was also measured. These results for both samples as determined by FACE analysis were similar to results previously reported, using more labor and time intensive procedures, validating the FACE protocols.

Microanalysis of enzyme digests of hyaluronan and chondroitin/dermatan sulfate by fluorophore-assisted carbohydrate electrophoresis (FACE)

Hyaluronan and chondroitin/dermatan sulfate are glycosaminoglycans that play major roles in the biomechanical properties of a wide variety of tissues, including cartilage. A chondroitin/dermatan sulfate chain can be divided into three regions: (1) a single linkage region oligosaccharide, through which the chain is attached to its proteoglycan core protein, (2) numerous internal repeat disaccharides, which comprise the bulk of the chain, and (3) a single nonreducing terminal saccharide structure. Each of these regions of a chondroitin/dermatan sulfate chain has its own level of microheterogeneity of structure, which varies with proteoglycan class, tissue source, species, and pathology. We have developed rapid, simple, and sensitive protocols for detection, characterization and quantitation of the saccharide structures from the internal disaccharide and nonreducing terminal regions of hyaluronan and chondroitin/dermatan sulfate chains. These protocols rely on the generation of saccharide structures with free reducing groups by specific enzymatic treatments (hyaluronidase/chondroitinase) which are then quantitatively tagged though their free reducing groups with the fluorescent reporter, 2-aminoacridone. These saccharide structures are further characterized by modification through additional enzymatic (sulfatase) or chemical (mercuric ion) treatments. After separation by fluorophore-assisted carbohydrate electrophoresis, the relative fluorescence in each band is quantitated with a cooled, charge-coupled device camera for analysis. Specifically, the digestion products identified are (1) unsaturated internal Deltadisaccharides including DeltaDiHA, DeltaDi0S, DeltaDi2S, DeltaDi4S, DeltaDi6S, DeltaDi2,4S, DeltaDi2,6S, DeltaDi4,6S, and DeltaDi2,4,6S; (2) saturated nonreducing terminal disaccharides including DiHA, Di0S, Di4S and Di6S; and (3) nonreducing terminal hexosamines including glcNAc, galNAc, 4S-galNAc, 6S-galNAc, and 4, 6S-galNAc.

Mononuclear leukocytes preferentially bind via CD44 to hyaluronan on human intestinal mucosal smooth muscle cells after virus infection or treatment with poly(I.C)

Pathological changes in inflammatory bowel disease include an increase in intestinal mucosal mononuclear leukocytes and hyperplasia of the muscularis mucosae smooth muscle cells (M-SMCs). Because virus infections have correlated with disease flare, we tested the response of cultured M-SMCs to respiratory syncytial virus, measles virus, and the viral analogue, poly(I.C). Adhesion of U937 cells and peripheral blood mononuclear cells was used to measure the leukocyte-interactive potential of M-SMCs. Untreated M-SMCs, only minimally adhesive for leukocytes, bound U937 cells after treatment with respiratory syncytial virus or measles virus. Mononuclear leukocytes also bound to poly(I.C)-treated M-SMCs. Although both vascular cell adhesion molecule-1 mRNA and protein increased 3-4-fold in poly(I.C)-treated M-SMC cultures, U937 cell adhesion was not blocked by an anti-vascular cell adhesion molecule-1 monoclonal antibody. However, hyaluronidase digestion of poly(I.C)- or virus-treated M-SMCs dramatically reduced leukocyte adhesion ( approximately 75%). Fluorophore-assisted carbohydrate electrophoresis demonstrated a approximately 3-fold increase in surface-bound hyaluronan on poly(I.C)-treated M-SMCs compared with untreated controls. In addition, pretreatment of mononuclear cells with a blocking anti-CD44 antibody, greatly decreased adhesion to poly(I.C)-treated M-SMCs. Recognition of this virus-induced hyaluronan/CD44 mechanism of mesenchymal cell/leukocyte interaction introduces a new avenue in the research of gut inflammation.

In vitro evaluation of synergism or antagonism with combinations of new cytotoxic agents

New cytotoxics with significant activity both in preclinical and clinical situations continued to be applied in the clinic by empiric means. The use of defined cell lines allows unanticipated antagonism between agents to be identified and to suggest synergistic combinations which need to be tested. By means of a semi-automated MTT assay and median effect analysis, we have identified antagonism in two couplets being evaluated in the clinic: etoposide with paclitaxel and vinorelbine with gemcitabine. Optimal use of these agents in man may require spacing these agents in time to prevent an adverse drug interaction between the agents which may diminish the potential response rate.

Differential effects of Staphylococcus aureus alpha-hemolysin on the synthesis of hyaluronan and chondroitin sulfate by rat chondrosarcoma chondrocytes

The plasma membranes of rat chondrosarcoma chondrocytes were permeabilized by treatment with alpha-hemolysin, the major toxin produced by Staphylococcus aureus, which forms small, stable, heptameric, transmembrane pores (1-2 nm in diameter) permitting influx/efflux of low-molecular-mass molecules (< or = 2000 Da). Treated chondrocytes were permeable to entry of trypan blue and exit of ATP. We describe the effects of alpha-hemolysin on the synthesis of hyaluronan (HA) and chondroitin sulfate (CS) by chondrocytes using the simple sugar [3H]glucosamine as a metabolic precursor. Chondrocytes permeabilized with alpha-hemolysin in serum-free media decreased intracellular ATP and synthesis of CS to approximately 5% of control within 2-4 h, but synthesized HA (80% of control for 8 h; approximately 65% of control at 24 h). Adding fresh medium (with or without serum) to permeabilized cells increased ATP significantly and increased HA synthesis to near initial control values. Under the same conditions, the recovery of CS synthesis approached initial levels in control but not permeabilized cells. Our model demonstrates that the biosynthesis of HA by these cells in vitro is remarkably stable to cellular perturbations which drastically inhibit synthesis of CS on proteoglycans.

Renal agenesis, ureteral ectopia into seminal vesicle, vas deferens agenesis and hemivertebra: an incomplete form of caudal regression syndrome?

The association of seminal vesicle cyst and upper urinary tract malformation is well known in the literature [1]. More rarely, urogenital malformations are associated with vertebral [2] or anorectal anomalies [3]. A 35-year-old infertile man with unilateral renal and deferential agenesis, seminal vesicle cyst and hemivertebra is reported. This complex malformative syndrome has been reported previously by Sheih et al. [4] and, to our knowledge, this is the third case described in the literature.

Unique synergism or antagonism of combinations of chemotherapeutic and hormonal agents in human prostate cancer cell lines

OBJECTIVE

To evaluate combinations of anti-tumour agents in tissue cultures using three established cell lines derived from patients with prostate cancer to obtain potential candidates for therapeutic testing in patients with prostate cancer.

MATERIALS AND METHODS

Seventeen anti-tumour agents were tested for synergism or antagonism in combination studies in DU 145, PC 3 and LnCaP cell lines. After determining the dose required for 50% inhibition of growth in each, combinations were screened using the median-effect plot and combination-index isobolograms.

RESULTS

Estramustine (the primary product of dephosphorylation of estramustine phosphate) showed strong synergism in all three cell lines with hydroxyflutamide, the non-immunosuppressive cyclosporin analogue PSC 833, and Liarozole. In the hormone-sensitive cell line LnCaP alone, synergism was also observed with vinblastine, paclitaxel, docetaxel, bicalutamide, ketoconazole and all-trans-retinoic acid. Other synergistic combinations of two agents were: Liarozole plus docetaxel in LnCaP, PSC 833 plus bicalutamide in DU 145 and PC 3, dexamethasone plus docetaxel in LnCaP, and finasteride plus hydroxyflutamide. Synergistic combinations of three agents were: estramustine plus PSC 833 and Liarozole and schedule-dependent combinations of estramustine, PSC 833, and all-trans-retinoic acid.

CONCLUSION

Some of the synergistic combinations have shown clinical effects in patients with hormone-refractory prostate cancer. Based on these findings, new combinations, e.g. estramustine with either PSC 833 or Liarozole, need to be clinically evaluated.

Epidermal growth factor modulates pepsinogen secretion in guinea pig gastric chief cells

BACKGROUND & AIMS

Although epidermal growth factor (EGF) inhibits gastric acid secretion, the effects it exerts on gastric chief cells are unknown. The aim of this study was to investigate whether EGF modulates pepsinogen release and intracellular Ca2+ concentrations ([Ca2+]i) and whether the effect involves mitogen-activated protein (MAP) kinase, eicosanoid generation, and nitric oxide.

METHODS

Chief cells were obtained by sequential digestion with collagenase and Ca2+ chelation. [Ca2+]i was measured in cells loaded with Fura-2 and NO generation by the NO coproduct citrulline.

RESULTS

In situ hybridization, immunohistochemistry, and immunoblotting showed that EGF receptor and MAP kinases were constitutively expressed in chief cells. EGF caused a concentration-dependent stimulation of pepsinogen secretion and MAP kinase activity and determined a 2.5-7.0-fold increase in [Ca2+]i, inositol 1,4,5-tryphosphate, prostaglandin E2, and leukotriene B4. Tyrosine kinase inhibitors and cyclooxygenase and lipoxygenase inhibitors reduced pepsinogen secretion and eicosanoid generation induced by EGF. EGF increased citrulline generation and guanosine 3',5'-cyclic monophosphate accumulation sixfold; the effect was blocked by NG monomethyl-L-arginine, which is an NO synthase inhibitor.

CONCLUSIONS

EGF stimulates pepsinogen secretion by activating eicosanoid generation, tyrosine kinases, MAP kinases, Ca2+, NO, and guanosine 3',5'-cyclic monophosphate.

Self-injection devices for intracavernosal pharmacotherapy: operational classification and safety considerations

Several self-injection devices have been recently proposed as an aid to home intracavernosal self-injection treatment for erectile dysfunction, with the purpose of allowing an easier drug administration, decreasing the artificiality of intracavernosal pharmacotheraphy, with the overall goal of increasing the acceptability of this treatment. We propose a classification of these devices according to the type of mechanical impact on the cavernosal tissue: self-injection pens, allowing for manual needle insertion and manual drug delivery; autoinsertors, with automatic needle insertion and manual drug delivery, and autoinjectors, that provide both automatic needle insertion and automatic drug delivery. The use of autoinjectors bears two theoretical risks: extra-corporal drug delivery in cases of wrong injection site, and trabecular damage due to high delivery pressure. In one device pressures 15 times higher the values reached by manual injection, and statistically higher than pressures obtained by maximal strength manual injection, were observed in an in-vitro investigation. Specific studies are needed to define a threshold pressure value for trabecular damage in the flaccid state; accordingly, information on autoinjector developed pressures should be provided by manufacturers. Clinical studies with adequate follow-up are needed as well, to verify the risk of autoinjector-induced extracorporal drug delivery, and the occurrence of intracavernosal nodules or penile curvature, compared to manual self-injection.

Clinical pharmacokinetics of amonafide (NSC 308847) in 62 patients

Amonafide (A) demonstrates dose-related increases in area under the curve (AUC) and Cmax values. Total body clearance for A (ranging from 44.2 to 53.8 L/hr/m2) is relatively constant within the dosing range of this study. The dose-related increase of AUC was also observed for the two identified metabolites, acetylamonafide (AA) and noramonafide (NA). A and NA plasma data could be described by a four-compartmental model (two compartments for A, one compartment each for NA and AA). The fitting for NA was poor owing to its low plasma concentration. The terminal half-lives for A, NA, and AA were in the range of 3-6 hr. No cumulative accumulation of parent compound or metabolites was detected after daily administration, The concentrations of A, NA, and AA 24 hr after dosing were either below or very close to the quantitative limits of the assay. Polymorphic disposition of A was confirmed by a frequency distribution of AUC value versus dose plot.

Nonreducing end structures of chondroitin sulfate chains on aggrecan isolated from Swarm rat chondrosarcoma cultures

Chondrocyte cultures derived from the Swarm rat chondrosarcoma were metabolically labeled with [35S]sulfate or [6-3H]GlcN. Radiolabeled aggrecan was purified from the cell layer and exhaustively digested with chondroitin ABC lyase. Digestion products were resolved into disaccharide and monosaccharide residues using Toyopearl HW40S chromatography. The separated saccharide pools were reduced with NaBH4 and applied onto a CarboPac PA1 column to resolve all of the internal disaccharide alditols (unsaturated) from the nonreducing end disaccharide (saturated) and monosaccharide alditols. Mercuric acetate treatment was used prior to carbohydrate analysis to identify unambiguously the saturated from the unsaturated disaccharides. The chondroitin sulfate (CS) chains from these aggrecan preparations contained: (a) an internal disaccharide composition of unsulfated (3-4 per chain), 4-sulfated (approximately 32 per chain), 6-sulfated (approximately 1 per 14 chains), and 4,6-sulfated disaccharides (approximately 1 per 6 chains) and (b) a nonreducing terminal composition of 4-sulfated GalNAc (approximately 4 out of every 7 chains), 4,6-disulfated GalNAc (approximately 2 out of every 7 chains), and GlcUA adjacent to a 4-sulfated GalNAc residue (approximately 1 out of every 7 chains). Thus, the vast majority of these CS chains terminated with a sulfated GalNAc residue. The presence of 4,6-disulfated GalNAc at nonreducing termini is 60-fold more abundant than 4,6-disulfated GalNAc in interior disaccharides. This observation is consistent with the suggestion that disulfation of terminal GalNAc residues is involved in chain termination.

Differential effects of brefeldin A on chondroitin sulfate and hyaluronan synthesis in rat chondrosarcoma cells

Brefeldin A, a fungal metabolite, interferes with vesicular transport causing disassembly of the Golgi complex with redistribution of Golgi components to the endoplasmic reticulum, and isolation of the trans-Golgi cisternae from the trans-Golgi network. We examined the effects of brefeldin A on the synthesis of hyaluronan and chondroitin sulfate by chondrocytes from the Swarm rat chondrosarcoma. Hyaluronan synthesis continues at a constant rate in the presence of brefeldin A for at least 8 h, and is therefore independent of vesicular transport. By contrast, chondroitin sulfate synthesis is rapidly inhibited (to < 1% within 15 min) by brefeldin A indicating that addition of chondroitin sulfate chains to the aggrecan core protein precursor requires vesicular transport. Removal of brefeldin A rapidly restored chondroitin sulfate chain elongation and sulfation on the aggrecan core protein precursor reaching 100% of control in 2 h and consistently establishing a higher steady state rate (up to 120%) by 4 h. Addition of p-nitrophenyl-beta-D-xylopyranoside, an exogenous acceptor for the synthesis of chondroitin sulfate chains, does not reverse the brefeldin A block. This suggests that xyloside-initiated synthesis of chondroitin sulfate depends on transport vesicles as might occur if the enzymes for synthesizing the linkage tetrasaccharide (i.e. galactosyltransferases) reside in the Golgi, while those required to elongate the chains reside in the trans-Golgi network. Recovery of chondroitin sulfate synthesis from brefeldin A treatment occurred efficiently in the presence of cycloheximide, indicating that the machinery for chondroitin sulfate synthesis reassembles from previously existing proteins. The results are consistent with the current model that hyaluronan synthesis occurs at the plasma membrane and is independent of vesicular transport, and with the hypothesis that the enzyme complex for chondroitin sulfate elongation and sulfation residues within the trans-Golgi network, and therefore isolated from the aggrecan core protein precursor in the presence of brefeldin A.

Effects of brefeldin A on aggrecan core protein synthesis and maturation in rat chondrosarcoma cells

In this paper, the effects of the fungal metabolite, brefeldin A, on the synthesis and maturation of aggrecan core protein precursor were studied in rat chondrosarcoma chondrocytes. The aggrecan core protein precursor was partially identified in total protein pools isolated from cell extracts based on its selective cleavage at a single site by the restriction protease factor Xa. During a 2-h labeling period with [3H]serine as precursor, brefeldin A inhibited the synthesis of mature aggrecan from its aggrecan core protein precursor consistent with an inhibition of chondroitin sulfate chain elongation and sulfation as described in the accompanying paper (Calabro, A., and Hascall, V. C. (1994) J. Biol Chem. 269, 22764-22770). This inhibition is presumably the result of the disruption of vesicular transport by brefeldin A, which isolates the aggrecan core protein precursor at the level of the trans-Golgi cisternae from the enzymes for chondroitin sulfate chain elongation and sulfation located in the trans-Golgi network. Brefeldin A also inhibited the exocytosis of all radiolabeled secretory proteins from the cell layer into the medium compartment, which is also consistent with the disruption of vesicular transport attributed to this metabolite. Although total protein synthesis was inhibited by 12% in the presence of brefeldin A, the aggrecan core protein precursor accumulated within the cell layer indicating that the inhibition of chondroitin sulfate synthesis by brefeldin A was not the result of a lack of aggrecan core protein precursor. When the brefeldin A block was removed and cultures chased in the presence of cycloheximide to prevent new protein synthesis, vesicular transport through the cell was re-established and chondroitin sulfate chains were added to a large proportion of the aggrecan core protein precursor that had accumulated during the brefeldin A block. These results suggest that the machinery for chondroitin sulfate synthesis and for protein exocytosis, that were disrupted by brefeldin A treatment, recover after removal of the brefeldin A, even in the presence of cycloheximide, and that the structures involved in these processes reassemble from previously existing proteins. Interestingly, two other proteins with the same relative abundance as the aggrecan core protein precursor were observed. An approximately 210-kDa protein with the characteristics of the fibronectin subunit, and an unidentified approximately 150-kDa protein which was efficiently cleaved by the protease Xa enzyme.

Anophthalmia and benomyl in Italy: a multicenter study based on 940,615 newborns

Following the report on clusters of anophthalmia and microphthalmia in England and Wales and their possible relation to the pesticide Benomyl, we analyzed the situation in Italy for the period 1986 to 1990 using data from the Italian registries of congenital malformations and national data on Benomyl use. Of 940,615 consecutive births, 33 cases of clinical anophthalmia and 78 cases of microphthalmia were reported (birth prevalence: 0.35 and 0.83/10,000). Birth prevalence by region for 18 of Italy's 20 political regions was evaluated for the two malformations, grouped together after exclusion of defects associated with chromosomal anomalies, no dishomogeneity in space or time among registries or among regions was observed for the study period. In no region was a statistically significant difference identified between observed and expected overall birth prevalence. Correlation analysis between the prevalence of micro/anophthalmia and Benomyl use by region showed a negative, nonsignificant coefficient, and an inverse correlation was found when the 18 regions were divided into four groups by increasing levels of Benomyl use. Parental occupation in agriculture did not seem to be associated with micro/anophthalmia when compared to a control group affected with isolated prearicular tags (odds ratio 0.63; CL 0.07-2.52). On the basis of these results, though the limits intrinsic to ecologic correlation studies must be taken into account, an association between Benomyl use and congenital micro/anophthalmia appears to be unlikely.

Human polyreactive and monoreactive antibodies: effect of glycosylation on antigen binding

The present experiments were initiated to determine whether the carbohydrate portions of antibody molecules contribute to polyreactivity. Cell lines making human monoclonal polyreactive or monoreactive antibodies of the immunoglobulin (Ig) M, IgG and IgA isotypes were treated with tunicamycin to block N-linked glycosylation of the proteins. Analysis of the secreted native and non-glycosylated proteins revealed a > 95% inhibition of [3H]mannose incorporation. Electrophoresis on sodium dodecyl sulphate-polyacrylamide gels of the proteins from tunicamycin-treated cells showed increased mobility and the absence of [3H]mannose incorporation of the immunoglobulin heavy chains, consistent with the lack of glycosylation. The native and non-glycosylated antibodies were then tested for their ability to bind different antigens. Despite the lack of glycosylation, both polyreactive and monoreactive antibodies bound to antigens with little if any loss of reactivity or specificity. It is concluded that the carbohydrate moieties do not contribute significantly to polyreactivity.

X-linked mental retardation, microcephaly, and growth delay associated with hereditary bullous dystrophy macular type: report of a second family

We report on 2 patients with mental retardation and bullous dystrophy, macular type. The observation of the condition in a male and his maternal uncle is consistent with recessive X-linkage. Due to the rarity of the condition, nosologic definition was difficult before the birth of the propositus. The clinical picture in the two patients described, characterized by mental retardation, dwarfism, microcephaly, alopecia, bullous dystrophy macular type, hypogenitalism, is very much like the one observed in the patients, all males, belonging to the only other family reported to date. The recent localization of the bullous dystrophy gene in the Xq24-qter segment opens the possibility of prenatal diagnosis.

Carotid artery endarterectomy in patients with contralateral carotid artery occlusion: perioperative hazards and late results

The aim of this study was to analyze and compare the perioperative hazards and late results of internal carotid endarterectomy (CEA) in patients with and without contralateral internal carotid artery occlusion. From March 1980 to April 1990, 375 consecutive patients underwent 439 CEAs at the First Department of Vascular Surgery of Padova Medical School. Patients were divided into two groups; group 1 (61 patients) had contralateral internal carotid artery occlusion and group 2 (314 patients) did not (378 CEAs, 64 bilateral). Indications for CEA were similar in both groups. The only significant difference in patient characteristics was a higher rate of previous stroke in group 1 (11% vs. 3%, p < 0.001). General anesthesia, continuous EEG monitoring, selective intraluminal shunt, and arteriotomy closure with a polytetrafluoroethylene patch (PTFE) were used routinely in both groups. An intraluminal shunt was inserted more frequently in group 1 than in group 2 (69% vs. 17%, p < 0.001). Major perioperative stroke occurred in one patient in each group (1.7% vs. 0.31%, respectively; NS). Early fatal stroke rates were 0% and 0.95% in groups 1 and 2, respectively (NS). All patients had neurologic examinations and duplex scans every 6 months (range 6 to 118 months; mean 42 months). Kaplan-Meier survival curves were virtually identical in the two groups; the majority of deaths were caused by myocardial infarction and cancer. There were no stroke-related deaths in group 1 as compared with 8.2% in group 2 (NS). New neurologic symptoms appeared in 4.7% of patients in group 1 and 6% in group 2 (NS) whereas the late stroke rates were 0% and 3.1%, respectively (NS).(ABSTRACT TRUNCATED AT 250 WORDS)

High-resolution separation of disaccharide and oligosaccharide alditols from chondroitin sulphate, dermatan sulphate and hyaluronan using CarboPac PA1 chromatography

Recent literature indicates that specific glycosaminoglycan structures are involved in various biological processes, such as anticoagulation, growth factor activation and viral infection. The initial step in the structural analysis of glycosaminoglycans is a definitive compositional analysis of its characteristic disaccharide repeat structures. Current chromatographic or electrophoretic procedures may have limitations in analysing glycosaminoglycan samples that are in low abundance, contain novel structures that need to be further characterized, or are metabolically labelled from radioactive precursors as a result of biosynthetic experiments. This study presents a new methodology for analysing disaccharides and oligosaccharides derived from chondroitin sulphate, dermatan sulphate and hyaluronan that fulfils the above criteria. The procedure involves the separation of reduced forms of these glycoconjugates on a CarboPac PA1 column using alkaline eluants. This study adopted a strategy which uses specific enzymes to release these disaccharides from their glycosaminoglycan forms. A borohydride reduction reaction was modified to be compatible with the buffer conditions commonly used with these enzymes in order to quantitatively reduce the disaccharides to their alditol forms (thereby stabilizing them to alkaline pH). Chromatography conditions were established which separated all known disaccharide alditol structures from chondroitin sulphate, dermatan sulphate and hyaluronan with extremely high resolution in a single run. Integrated pulsed amperometry was compared to UV absorbance measurement at 232 nm as two sensitive methods for detecting these reduced disaccharides; most of them could be routinely detected in the range of 50-500 ng. Data are presented applying this method to quantify hyaluronan in a biological sample which contains approximately 5000 cells and only approximately 10 ng of hyaluronan. Additional data are presented to demonstrate that this procedure will also separate oligosaccharide alditols derived from hyaluronan.

Uronic acid-containing glycosaminoglycans and keratan sulfate are present in the tectorial membrane of the inner ear: functional implications

The tectorial membrane is a gel-like, acellular connective tissue overlying the microscopic organ of Corti--the auditory sensory structure. It is instrumental in the sound-synchronous deflection of the stereocilia of the hair cells, a central event in auditory transduction. It is well established that collagen, primarily type II, constitutes the major protein of the tectorial membrane, with smaller amounts of types IX and XI also present. However, conclusive information on the proteoglycans in this structure is lacking. Tectorial membranes were extracted with a 4 M guanidine--HCl solvent, and proteoglycans isolated after ethanol precipitation and collagenase treatment. A colorimetric assay based on the binding of the cationic dye safranin O to glycosaminoglycans, in combination with enzymatic techniques, detected significant amounts of chondroitin sulfate and keratan sulfate (0.29 and 0.17% on a wet weight basis, respectively). Agarose-polyacrylamide electrophoresis of chondroitinase-digested samples revealed a core protein with a similar molecular mass to that of the large cartilage proteoglycan aggrecan. This proteoglycan reacted with the antibody 3-B-3 (recognizing modified chondroitin 6-sulfate linkage region oligosaccharides). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed several low molecular mass proteins which reacted with 5-D-4, specific for keratan sulfate, one of which showed characteristics of fibromodulin. Comparison of the quantitative aspects of various connective tissue components of tectorial membrane with other type II collagen-containing structures revealed that this tissue resembles highly hydrated cartilage.

Electrical stimulation of the dorsal nerve of the penis evokes reflex tonic erections of the penile body and reflex ejaculatory responses in the spinal rat

An animal model using the spinal rat was characterized. Electrical stimulation of the dorsal nerve of the penis elicited reflex tonic erections of the penile body and reflex bulbospongiosus muscle activity, flips and ejaculations. The tonic erections of the penile body are independent from contractions of the bulbospongiosus muscle and appear to be the result of a neurovascular process. Our observations suggest that reflex bulbospongiosus muscle activity, flips and ejaculations are a single complex reflex response, which we define as reflex ejaculatory response. Two parameters predicted the occurrence and type of reflex response. The visualization of bulbospongiosus muscle activity during surgical isolation of the dorsal nerve of the penis was sufficient to anticipate the elicitability of reflex ejaculatory responses. The latter, together with a systemic systolic pressure > or = 73 mmHg., warranted the elicitability of reflex tonic erections. The similarities found in the physiology of rat tonic penile body erections and of human erections make this model promising for further elucidation of sexual function. Moreover, the present model may prove useful for the investigation of neurogenic erectile dysfunction, and of neurogenic ejaculatory disorders.

Analysis of water-macromolecule proton magnetization transfer in articular cartilage

These studies were designed to establish which structural elements of cartilage are responsible for proton magnetization transfer between water (Hf) and macromolecules (Hr) observed in MRI studies on articular cartilage. Saturation transfer techniques were used to monitor magnetization transfer in vitro on samples of the two major constituents of cartilage: collagen and proteoglycan. Articular cartilage samples were also evaluated in vitro before and after the removal of the proteoglycan fraction. Isolated hydrated collagen exhibited a significant proton magnetization transfer rate with water. In contrast, proteoglycans exhibited no proton magnetization transfer. Articular cartilage, in vitro, exhibited a high degree of magnetization transfer with water protons consistent with previous MRI studies in vivo. Enzymatic removal of proteoglycan from the cartilage did not alter the magnetization transfer rate between Hr and Hf. These data demonstrate that the structure and concentration of the collagen matrix are the predominant determinants of the magnetization transfer process in articular cartilage with little or no contribution from proteoglycans. This specificity of the magnetization transfer effect may prove useful in the noninvasive evaluation of cartilage composition and structure in vivo.

Omphalocele and gastroschisis: a collaborative study of five Italian congenital malformation registries

During 1984-1989, 116 cases of omphalocele and 42 cases of gastroschisis were detected among 736,760 consecutive births in the area covered by five Italian congenital malformation registries. The prevalence rate was 1.6 per 10,000 for omphalocele and 0.6 per 10,000 for gastroschisis. Three additional cases were detected among spontaneous abortions, giving a total of 117 cases of omphalocele and 44 of gastroschisis. No variations in prevalence rates were observed among registries. A cluster of omphalocele was found in 1989 in Firenze. All cases were sporadic except for one infant with two sibs with Beckwith-Wiedemann syndrome. A predominance of male infants was observed for both defects. This study confirms the very young maternal age for isolated gastroschisis as compared to that for omphalocele and controls. Birth weight and the percentage of small-for-date is different among isolated gastroschisis, omphalocele and controls. Associated anomalies occurred in 45 cases of omphalocele and 11 cases of gastroschisis. Our data confirm the association of omphalocele with trisomies 13 and 18. Twelve cases of omphalocele and gastroschisis with associated limb defects were classified as limb body wall complex. The possible differences in etiopathology between omphalocele and gastroschisis, both isolated and associated, are discussed.

Monoclonal antibodies directed against epitopes within the core protein structure of the large aggregating proteoglycan (aggrecan) from the swarm rat chondrosarcoma

The core protein of the large hyaline cartilage proteoglycan, aggrecan, is composed of six distinct domains: globular 1 (G1), interglobular, globular 2 (G2), keratan sulfate attachment, chondroitin sulfate (CS) attachment, and globular 3 (G3). Monoclonal antibodies that recognize epitopes in these domains were raised against Swarm rat chondrosarcoma aggrecan that was either denatured through reduction and alkylation or partially deglycosylated through chondroitinase ABC digestion or alkali elimination, the latter with or without sulfite addition. Monoclonal antibodies were further characterized for reactivity to purified aggrecan substructures including rat chondrosarcoma G1 and CS attachment domains, a recombinant rat chondrosarcoma G3 domain fusion protein, bovine articular cartilage G2 domain, and rat chondrosarcoma link protein (LP). Biochemical characterization of the specificities of these monoclonal antibodies indicated that one (1C6) recognized an epitope shared by both the G1 and the G2 domains; one (5C4) recognized an epitope shared by both LP and the G1 domain; one (7D1) recognized an epitope shared by both the G1 and the CS attachment domains; two (14A1 and 15B2) recognized epitopes in the CS attachment domain; one (14B4) recognized an epitope in the G3 domain; and one (13D1) recognized a ubiquitous epitope shared by the G1, G2, G3, and CS attachment domains of aggrecan and also LP. Collectively the specificities of these antibodies confirm the occurrence of multiple repeated epitopes (both carbohydrate and protein in nature) throughout the different domain structures of aggrecan. These antibodies have been proven to be useful for identifying aggrecan-like molecules in several connective tissues other than cartilage.

[Spondylo-costal dysostosis: presentation of a new case with autosomal dominant heredity and discussion of problems in genetic counseling]

The Authors report a new family with spondylo-costal dysplasia in which three members in three generation are affected. The genetic heterogeneity of the condition and its implication in genetic counseling is discussed.

Hypomelanosis of Ito associated with chromosomal translocation involving Xp11

We report on a 3-year-old girl with hypomelanosis of Ito (HI). She has typical skin lesions and mild CNS involvement characterized by impaired walking and borderline mental retardation. Cytogenetic investigation showed a 18/X translocation with breakpoint on Xp11. This is the sixth case of HI in which this breakpoint has been reported, underlining that this event cannot be considered coincidental. Further studies are needed to understand the etiologic and pathogenetic meaning of this finding.