Monoclonal antibody to transferrin receptor blocks transferrin binding and inhibits human tumor cell growth in vitro

A murine hybridoma has been obtained that produces a monoclonal antibody against the human transferrin receptor. In contrast to previously characterized monoclonal antibodies that recognize the transferrin receptor, this antibody, designated 42/6, blocks the binding of transferrin to its receptor and inhibits the growth of the human T leukemic cell line, CCRF-CEM, in vitro. Inhibition of cell growth was dose dependent, and as little as 2.5 micrograms of purified antibody per ml had a detectable effect, even though transferrin was present in the tissue culture medium in large molar excess. Cells grown in the presence of antibody for 7 days accumulated in S phase of the cell cycle. The addition of iron to antibody-treated cultures in the form of ferric complexes or ferrous sulfate did not overcome the growth inhibitory effects of the anti-transferrin-receptor antibodies. This result suggests that either transferrin is the only means by which CCRF-CEM leukemic cells can be provided with sufficient iron in vitro or that other factors in addition to iron starvation are involved in the antibody-mediated growth inhibition. The inhibition of cell growth by 42/6 monoclonal antibody suggests that monoclonal antibodies against proliferation-associated cell surface antigens, such as the transferrin receptor, may be useful pharmacological reagents to modify cell growth in vitro.

Large-scale statistical analyses of rice ESTs reveal correlated patterns of gene expression

Large, publicly available collections of expressed sequence tags (ESTs) have been generated from Arabidopsis thaliana and rice (Oryza sativa). A potential, but relatively unexplored application of this data is in the study of plant gene expression. Other EST data, mainly from human and mouse, have been successfully used to point out genes exhibiting tissue- or disease-specific expression, as well as for identification of alternative transcripts. In this report, we go a step further in showing that computer analyses of plant EST data can be used to generate evidence of correlated expression patterns of genes across various tissues. Furthermore, tissue types and organs can be classified with respect to one another on the basis of their global gene expression patterns. As in previous studies, expression profiles are first estimated from EST counts. By clustering gene expression profiles or whole cDNA library profiles, we show that genes with similar functions, or cDNA libraries expected to share patterns of gene expression, are grouped together. Promising uses of this technique include functional genomics, in which evidence of correlated expression might complement (or substitute for) those of sequence similarity in the annotation of anonymous genes and identification of surrogate markers. The analysis presented here combines the application of a correlation-based clustering method with a graphical color map allowing intuitive visualization of patterns within a large table of expression measurements.

Use of solid-phase microextraction for the quantitative determination of herbicides in soil and water samples

An in-depth study of SPME optimization and application has been made, considering not only aqueous (surface water and groundwater samples) but also the more complex soil samples. Seven herbicides widely used in the area of study have been selected including five triazine herbicides (atrazine, simazine, terbumeton, terbuthylazine, terbutryn), molinate, and bromacil. linearity range was between 0.1 and 10 ng/mL and the repeatability below 10% when applying the optimized SPME procedure to water samples. Reproducibility was found to be lower than 20% at the 1 ng/mL level, and the limits of determination in environmental water samples using GC/MS (SIM mode) were well below 0.1 ng/mL (values ranging from 10 to 60 ng/L). Extraction of selected herbicides from soil was carried out by microwave-assisted solvent extraction using methanol in screw-capped vials, leading to recoveries over 80% in spiked soil samples at the 5-200 ng/g level. SPME application over methanolic soil extracts required a 10-fold dilution with distilled water. The recommended procedure was found to be fully applicable for quantitative determination of selected herbicides in soils containing low organic matter content with coefficients of variation below or around 10% and limits of determination ranging from 1 to 10 ng/g. Both procedures were applied to real-world surface water and soil samples where several pesticides were detected including atrazine, simazine, terbuthylazine, and molinate.

Identification of Apo B-100 segments mediating the interaction of low density lipoproteins with arterial proteoglycans

The interactions of low density lipoprotein (LDL) and apolipoprotein (apo) B-100 segments with chondroitin-6-SO4 rich aortic proteoglycans aggregate (CSPG) were studied by using quantitative frontal elution affinity chromatography. The affinity of the agarose-CSPG was higher for LDL than for very low density lipoprotein and high density lipoprotein was not bound. LDL from different individuals had dissociation coefficients (Kd) from 28 to 179 nM. Experiments with tryptic hydrolysates of apo B suggested that the capacity of LDL to bind with CSPG resides in the protein. Nine apo B-100 hydrophilic peptides, 12 to 26 amino acids long, were selected, and three were found to interact with the agarose-bound CSPG: apo B P-1 (LRKHKLIDVISMYRELLKDLSKEA, residues 4230 to 4254), apo B P-2 (RLTRKRGLKLATALSLSNK, residues 3359 to 3377), and apo B P-11 (RQVSHAKEKLTALTKK, residues 2106 to 2121). These peptides competed with LDL for binding to the agarose-bound and soluble CSPG; apo B P-2 was the most effective. This correlates with Kd values: 63, 86, and 82 microM for apo B P-2, P-1, and P-11, respectively. The peptides shared an excess of positive-charged side chains. Apo B P-2 belongs to the lys- and arg-rich, LDL-receptor domain. Apo E also binds to the agarose-proteoglycan. The results suggest that apo B regions with sequences and charge distributions analogous to those of residues 3359 to 3377, 4230 to 4254, and 2106 and 2121 are among those responsible for the interaction of LDL with intima-media CSPG.

Modalities of synthesis of Ki67 antigen during the stimulation of lymphocytes

The antibody Ki67 is currently used to evaluate the proliferative fraction of solid tumors and some hematological malignancies. We have used phytohemagglutinin (PHA)-stimulated peripheral blood lymphocytes as a model to study the entry of quiescent cells into cell cycle and to follow their progress to the next cycle. Flow cytometric analysis of lymphocyte samples stained with the antibody Ki67 and a DNA marker has allowed us to follow the expression of Ki67 antigen (Ki67 Ag) as a function of the position of the cells in the cell cycle. The use of drugs blocking the stimulated lymphocytes in different phases of the cell cycle permitted us to demonstrate that Ki67 Ag expression started from the beginning of the first S phase. The level of Ki67 Ag increased during S phase until mitosis, when its expression was maximal. After division, the cells in G1 phase showed a decrease in Ki67 Ag expression (possibly corresponding to degradation) until they reentered S phase, when the level of Ki67 Ag increased again. The results confirm that the expression of Ki67 Ag is related to the proliferative state of the cells and suggest that it may be used to determine the proliferative cell fraction in hematopoietic tissues.

The tyrosine phosphatase SHP-1 associates with the sst2 somatostatin receptor and is an essential component of sst2-mediated inhibitory growth signaling

Activation of the somatostatin receptor sst2, a member of the Gi protein-coupled receptor family, results in the stimulation of a protein-tyrosine phosphatase activity involved in the sst2-mediated growth inhibitory signal. Here, we report that SHP-1, a cytoplasmic protein-tyrosine phosphatase containing two Src homology 2 domains constitutively associated with sst2 as evidence by coprecipitation of SHP-1 protein with sst2, in Chinese hamster ovary cells coexpressing sst2 and SHP-1. Activation of sst2 by somatostatin resulted in a rapid dissociation of SHP-1 from sst2 accompanied by an increase of SHP-1 activity. SHP-1 was phosphorylated on tyrosine in control cells and somatostatin induced a rapid and transient dephosphorylation on tyrosine residues of the enzyme. Stimulation of SHP-1 activity by somatostatin was abolished by pertussis toxin pretreatment of cells. Gialpha3 was specifically immunoprecipitated by anti-sst2 and anti-SHP-1 antibodies, and somatostatin induced a rapid dissociation of Gialpha3 from sst2, suggesting that Gialpha3 may be involved in the sst2.SHP-1 complexes. Finally, somatostatin inhibited the proliferation of cells coexpressing sst2 and SHP-1, and this effect was suppressed in cells coexpressing sst2 and the catalytic inactive SHP-1 (C453S mutant). Our data identify SHP-1 as the tyrosine phosphatase associated with sst2 and demonstrate that this enzyme may be an initial key transducer of the antimitogenic signaling mediated by sst2.

Evaluation of Kodak EDR2 film for dose verification of intensity modulated radiation therapy delivered by a static multileaf collimator

A new type of radiographic film, Kodak EDR2 film, was evaluated for dose verification of intensity modulated radiation therapy (IMRT) delivered by a static multileaf collimator (SMLC). A sensitometric curve of EDR2 film irradiated by a 6 MV x-ray beam was compared with that of Kodak X-OMAT V (XV) film. The effects of field size, depth and dose rate on the sensitometric curve were also studied. It is found that EDR2 film is much less sensitive than XV film. In high-energy x-ray beams, the double hit process is the dominant mechanism that renders the grains on EDR2 films developable. As a result, in the dose range that is commonly used for film dosimetry for IMRT and conventional external beam therapy, the sensitometric curves of EDR2 films cannot be approximated as a linear function, OD = c * D. Within experimental uncertainty, the film sensitivity does not depend on the dose rate (50 vs 300 MU/min) or dose per pulse (from 1.0 x 10(-4) to 4.21 x 10(-4) Gy/pulse). Field sizes and depths (up to field size of 10 x 10 cm2 and depth = 10 cm) have little effect on the sensitometric curves. Percent depth doses (PDDs) for both 6 and 23 MV x rays were measured with both EDR2 and XV films and compared with ion chamber data. Film data are within 2.5% of the ion chamber results. Dose profiles measured with EDR2 film are consistent with those measured with an ion chamber. Examples of measured IMRT isodose distributions versus calculated isodoses are presented. We have used EDR2 films for verification of all IMRT patients treated by SMLC in our clinic. In most cases, with EDR2 film, actual clinical daily fraction doses can be used for verification of composite isodose distributions of SMLC-based IMRT.

Logical modelling of regulatory networks with GINsim 2.3

Many important problems in cell biology require the consideration of dense nonlinear interactions between functional modules. The requirement of computer simulation for the understanding of cellular processes is now widely accepted, and a variety of modelling frameworks have been designed to meet this need. Here, we present a novel public release of the Gene Interaction Network simulation suite (GINsim), a software designed for the qualitative modelling and analysis of regulatory networks. The main functionalities of GINsim are illustrated through the analysis of a logical model for the core network controlling the fission yeast cell cycle. The last public release of GINsim (version 2.3), as well as development versions, can be downloaded from the dedicated website (http://gin.univ-mrs.fr/GINsim/), which further includes a model library, along with detailed tutorial and user manual.

A high-resolution radiation hybrid map of the human genome draft sequence

We have constructed a physical map of the human genome by using a panel of 90 whole-genome radiation hybrids (the TNG panel) in conjunction with 40,322 sequence-tagged sites (STSs) derived from random genomic sequences as well as expressed sequences. Of 36,678 STSs on the TNG radiation hybrid map, only 3604 (9.8%) were absent from the unassembled draft sequence of the human genome. Of 20,030 STSs ordered on the TNG map as well as the assembled human genome draft sequence and the Celera assembled human genome sequence, 36% of the STSs had a discrepant order between the working draft sequence and the Celera sequence. The TNG map order was identical to one of the two sequence orders in 60% of these discrepant cases.

Gut mucosal atrophy after a short enteral fasting period in critically ill patients

PURPOSE

The purpose of this study was to evaluate the presence of gut mucosal atrophy and changes in mucosal permeability in critically ill patients after a short fasting period.

MATERIALS AND METHODS

Fifteen critically ill patients underwent a period of enteral fasting of at least 4 days (mean 7.8 days). We took the following measurements the day before initiating enteral nutrition: indirect calorimetry, serum albumin, prealbumin, and lymphocyte count. We also performed a duodenal endoscopic biopsy with histopathological and mucosal morphometric analysis including villus height and crypt depth. The lactulose-mannitol test was performed to assess gut permeability. A total of 28 healthy volunteers served as controls for duodenal biopsy or lactulose-mannitol test. Clinical data, such as length of fasting, severity score, and previous parenteral nutritional support, were recorded.

RESULTS

We found gut mucosal atrophy, expressed as a decrease in villus height and crypt depth, in patients compared with controls. The patients also exhibited an abnormal lactulose-mannitol test. Morphometric changes did not correlate with permeability. Further, we found no correlation between the results of the lactulose-mannitol test and of mucosal morphometry with clinical data.

CONCLUSIONS

We found that a short period of enteral fasting was associated with significant duodenal mucosal atrophy and abnormal gut permeability in critically ill patients.

Solid-phase microextraction for quantitative analysis of organophosphorus pesticides in environmental water samples

Solid-phase microextraction (SPME) is a relatively new technique that appears as a convenient and efficient extraction method in contrast with more complex techniques used for pesticide residue analysis based on liquid-liquid and solid-phase extraction. This extraction procedure involves the absorption of analytes into a polymeric film coated onto a fine silica fiber directly dipped in the aqueous sample. An SPME procedure for the determination of 12 organophosphorus pesticides in clean environmental water samples at low ng/ml concentration level has been developed by optimising variables involved in extraction and desorption. The absorption equilibrium has been estimated by mathematical treatment of the process using an expression that describes experimental absorption time profiles. The method was evaluated according to the reproducibility, linearity range and limits of detection using two different fiber coatings: 100 microm polydimethylsiloxane and 85 microm polyacrylate. The limits of detection obtained using nitrogen-phosphorus detection ranged between 0.01 and 0.2 ng/ml with relative standard deviations lower than 15% at the 1 ng/ml level. The method showed good linearity between 0.1 and 10 ng/ml with regression coefficients ranging between 0.97 and 0.999. Determination of organophosphorus pesticides in water samples in concentration below 0.1 ng/ml can be easily carried out with this fast, economic and solvent-free SPME procedure.

Colocalization of galanin and luteinizing hormone-releasing hormone in a subset of preoptic hypothalamic neurons: anatomical and functional correlates

Colocalization of neurotransmitters, including neuropeptides and amines, in the same neuron of certain areas or well-defined nuclei of the central and peripheral nervous systems appears to be the rule rather than the exception. The coexistent neurotransmitters can be coreleased and interact at pre- and postsynaptic levels in a synergistic or antagonistic manner. Galanin is a recently isolated and characterized "gut-brain" peptide. It is colocalized with many neurotransmitters in both the central and the peripheral nervous systems. Among other regions in the central nervous system, galanin is present in neuronal perikarya of the septum and the hypothalamus. The dense accumulation of nerve terminals in the external zone of the median eminence suggests that galanin is an important peptide regulating neuroendocrine functions. Although most galanin and luteinizing hormone-releasing hormone (LHRH) neurons have a distinctly different morphology, a subset of galanin-immunoreactive perikarya in the diagonal band of Broca and the medial preoptic area, near the organum vasculosum of the lamina terminalis, have morphological features similar to those of LHRH neurons. By using double-labeling immunocytochemistry, we have found that in the preoptic region of the male rat brain approximately 15-20% of these "LHRH-like" galanin-immunoreactive neurons are also immunopositive for LHRH. Moreover, in the medial preoptic area and the diagonal band of Broca, some of the single-labeled LHRH cells are surrounded with galanin-immunoreactive nerve terminals, suggesting that LHRH perikarya have synaptic contacts with galanin-immunoreactive terminals. Additional studies indicated that galanin can readily enhance in vitro release of LHRH from nerve terminals in the median eminence. The observations that (i) galanin is coexpressed with LHRH, (ii) galanin seems to innervate LHRH-producing neurons, and (iii) galanin acts as a putative neurotransmitter to enhance the release of LHRH suggest that galanin should be considered an important regulator of LHRH-containing neurons and, therefore, of reproductive functions.

Alternate polyadenylation in human mRNAs: a large-scale analysis by EST clustering

Alternate polyadenylation is an important post-transcriptional regulatory process now open to large-scale analysis by use of cDNA databases. We clustered 164,000 expressed sequence tags (ESTs) into approximately 15,000 groups and aligned each group to a putative mRNA 3' end. By use of stringent criteria to discard artifactual mRNA extremities, clear evidence for alternate polyadenylation was obtained in 189 of the 1000 EST clusters studied. A number of previously unreported polyadenylation sites were identified, together with possible instances of tissue-specific differential polyadenylation. This study demonstrates that, besides quantitative aspects of gene expression, the distribution of alternate mRNA forms can be analyzed through EST sampling.

sst2 somatostatin receptor mediates negative regulation of insulin receptor signaling through the tyrosine phosphatase SHP-1

We have previously reported in Chinese hamster ovary (CHO) cells expressing sst2 that activation of the sst2 somatostatin receptor inhibits insulin-induced cell proliferation by a mechanism involving stimulation of a tyrosine phosphatase activity. Here we show that the tyrosine phosphatase SHP-1 was associated with the insulin receptor (IR) at the basal level. Activation of IR by insulin resulted in a rapid and transient increase of tyrosine phosphorylation of IR, its substrates IRS-1 and Shc, and also of SHP-1. This was then followed by a rapid dephosphorylation of these molecules, which was related to the insulin-induced increase of SHP-1 association to IR and of SHP-1 activity. On the other hand, addition to insulin of the somatostatin analogue, RC160, resulted in a higher and faster increase of SHP-1 association to IR directly correlated with an inhibition of phosphorylation of IR and its substrates, IRS-1 and Shc. RC160 also induced a higher and more sustained increase in SHP-1 activity. Furthermore, RC160 completely suppressed the effect of insulin on SHP-1 phosphorylation. Finally, in CHO cells coexpressing sst2 and a catalytically inactive mutant SHP-1, insulin as well as RC160 could no longer stimulate SHP-1 activity. Overexpression of the SHP-1 mutant prevented the insulin-induced signaling to be terminated by dephosphorylation of IR, suppressed the inhibitory effect of RC160 on insulin-induced IR phosphorylation, and abolished the cell proliferation modulation by insulin and RC160. Our results suggest that SHP-1 plays a role in negatively modulating insulin signaling by association with IR. Furthermore, somatostatin inhibits the insulin-induced mitogenic signal by accelerating and amplifying the effect of SHP-1 on the termination of the insulin signaling pathway.

Functional analysis of Plasmodium vivax VIR proteins reveals different subcellular localizations and cytoadherence to the ICAM-1 endothelial receptor

The subcellular localization and function of variant subtelomeric multigene families in Plasmodium vivax remain vastly unknown. Among them, the vir superfamily is putatively involved in antigenic variation and in mediating adherence to endothelial receptors. In the absence of a continuous in vitro culture system for P. vivax, we have generated P. falciparum transgenic lines expressing VIR proteins to infer location and function. We chose three proteins pertaining to subfamilies A (VIR17), C (VIR14) and D (VIR10), with domains and secondary structures that predictably traffic these proteins to different subcellular compartments. Here, we showed that VIR17 remained inside the parasite and around merozoites, whereas VIR14 and VIR10 were exported to the membrane of infected red blood cells (iRBCs) in an apparent independent pathway of Maurer's clefts. Remarkably, VIR14 was exposed at the surface of iRBCs and mediated adherence to different endothelial receptors expressed in CHO cells under static conditions. Under physiological flow conditions, however, cytoadherence was only observed to ICAM-1, which was the only receptor whose adherence was specifically and significantly inhibited by antibodies against conserved motifs of VIR proteins. Immunofluorescence studies using these antibodies also showed different subcellular localizations of VIR proteins in P. vivax-infected reticulocytes from natural infections. These data suggest that VIR proteins are trafficked to different cellular compartments and functionally demonstrates that VIR proteins can specifically mediate cytoadherence to the ICAM-1 endothelial receptor.

Signal transduction of somatostatin receptors negatively controlling cell proliferation

Somatostatin acts as an inhibitory peptide of various secretory and proliferative responses. Its effects are mediated by a family of G-protein-coupled receptors (sst1-5) that can couple to diverse signal transduction pathways such as inhibition of adenylate cyclase and guanylate cyclase, modulation of ionic conductance channels, and protein dephosphorylation. The five receptors bind the natural peptide with high affinity but only sst2, sst5 and sst3 bind the short synthetic analogues. Somatostatin negatively regulates the growth of various normal and tumour cells. This effect is mediated indirectly through inhibition of secretion of growth-promoting factors, angiogenesis and modulation of the immune system. Somatostatin can also act directly through sst receptors present on target cells. The five receptors are expressed in various normal and tumour cells, the expression of each receptor being receptor subtype and cell type specific. According to the receptor subtypes, distinct signal transduction pathways are involved in the antiproliferative action of somatostatin. Sst1, 4 and 5 modulate the MAP kinase pathway and induce G1 cell cycle arrest. Sst3 and sst2 promote apoptosis by p53-dependent and -independent mechanisms, respectively.

Galanin stimulates luteinizing hormone-releasing hormone secretion from arcuate nucleus-median eminence fragments in vitro: involvement of an alpha-adrenergic mechanism

Galanin (GAL), a 29-amino acid peptide originally isolated from porcine intestine, has been shown to be widely distributed not only in the gut, but also in the central nervous system. Several studies have shown that GAL participates in the hypothalamic regulation of PRL, GH, and LH secretion. In this study, we evaluate the effects of rat GAL (rGAL) on LHRH and prostaglandin (PG) E2 release from arcuate nucleus-median eminence fragments in vitro. Fragments were incubated for 30-min periods in Krebs-Ringer bicarbonate buffer containing the different test substances. The addition to the medium of rGAL in concentrations ranging from 5-1000 nM increased the release of both LHRH and PGE2 in a concentration-dependent manner. The ED50 values were approximately 55 and 80 nM for LHRH and PGE2, respectively. rGAL-induced LHRH and PGE2 release were related, as suggested by the finding that the addition to the medium of indomethacin (10 microM), a PG synthesis blocker, completely blocked rGAL-induced LHRH release. In addition, an active catecholaminergic system appears to be necessary for obtaining the stimulatory effect of rGAL. The addition to the medium of the alpha-adrenergic blocker phentolamine or prazosin impaired the ability of rGAL to release both LHRH and PGE2. rGAL-induced stimulation of LHRH and PGE2 release was blocked by phentolamine at doses of 1-10 microM, while prazosin was able to block it at doses as low as 0.1 microM. In summary, rGAL stimulates LHRH and PGE2 release from arcuate nucleus-median eminence fragments in vitro in a dose-dependent fashion. Such an effect is blocked by both indomethacin and alpha-adrenergic blockers, indicating that rGAL-induced stimulation of LHRH secretion is exerted through alpha-adrenergic receptors and requires PGE2 as an intracellular mediator.

Transplantation with selected autologous peripheral blood CD34+Thy1+ hematopoietic stem cells (HSCs) in multiple myeloma: impact of HSC dose on engraftment, safety, and immune reconstitution

OBJECTIVE

The aims of our study performed in myeloma were to evaluate the performance and the safety of Systemix's high-speed clinical cell sorter, to assess the safety and efficacy of deescalating cell dose cohorts of CD34+Thyl+ hematopoietic stem cells (HSCs) as autologous grafts by determining engraftment, and to assess the residual tumor cell contamination using polymerase chain reaction (PCR) amplification assays of patient-specific complementarity determining region III (CDR III) analysis for residual myeloma cells.

MATERIALS AND METHODS

The clinical trial was performed in 31 multiple myeloma patients, using purified human CD34+Thyl+ HSCs mobilized from peripheral blood with cyclosphosphamide and granulocyte-macrophage colony-stimulating factor to support a single transplant after high-dose melphalan 140 mg/m2 alone (cohort 1) and with total body irradiation (TBI) (cohorts 2-5) after an HSC transplant cell dose de-escalation/escalation design.

RESULTS

Twenty-three patients were transplanted. Engraftment data in the melphalan + TBI cohorts confirmed that HSC doses above the threshold dose of 0.8 x 10(6) CD34+Thy1+ HSCs/ kg provided prompt engraftment (absolute neutrophil count >0.5 x 10(9)/L day 10; platelet count >50 x 10(9)/L day 13). A higher rate of infections was observed in the early and late follow-up phases than usually reported after CD34+ selected or unselected autologous transplantation, which did not correlate with the CD34+Thy1+ HSC dose infused. Successful PCR for CDR III could only be performed in five patients on initial apheresis product and final CD34+Thy1+ HSC product and showed a median tumor log reduction >3.12.

CONCLUSIONS

CD34+Thy1+ HSCs are markedly depleted or free of detectable tumor cells in multiple myeloma and are capable of producing fast and durable hematopoietic reconstitution at cell doses >0.8 x 10(6) CD34+Thy1+ HSCs/kg. The delayed immune reconstitution observed is not different from that described in unselected autologous bone marrow and peripheral blood mononucleated cells transplants in multiple myeloma and may be corrected by addition of T cells either to the graft or to the patient in the posttransplant phase.

Induction of promiscuous G protein coupling of the follicle-stimulating hormone (FSH) receptor: a novel mechanism for transducing pleiotropic actions of FSH isoforms

Under physiological conditions, FSH is secreted into the circulation as a complex mixture of several isoforms that vary in the degree of glycosylation. Although it is well established that the glycosylation of FSH is important for the serum half-life of the hormone and coupling of the receptor to adenylate cyclase, little is known concerning how physiologically occurring glycosylation patterns of this hormone affect receptor signaling. In this study, we have examined the biological activity of deglycosylated human FSH (DeGly-phFSH), recombinant mammalian-expressed hFSH (CHO-hFSH), and insect cell-expressed hFSH (BV-hFSH, alternatively glycosylated) as compared with that of purified human pituitary FSH (phFSH) using a Chinese hamster ovarian cell line stably expressing the hFSH receptor (3D2 cells). Differentially glycosylated forms of FSH did not bind to the FSH receptor in the same manner as phFSH. Although all hormones showed similar potency in competing for [125I]phFSH binding to the hFSH receptor, competition curves for deglycosylated and insect cell-produced FSH were steeper. Similarly, glycosylation of FSH had a profound effect on bioactivity of the hormone. Purified hFSH produced a sigmoidal dose-dependent stimulation in cAMP production, whereas DeGly-phFSH and BV-hFSH induced biphasic (bell-shaped) dose-response curves. BV-hFSH also elicited biphasic effects on steroidogenesis in primary cultures of rat granulosa cells. The cellular response to BV-hFSH was dependent on the degree of receptor-transducer activation. BV-hFSH bioactivity was strictly inhibitory when combined with the ED80 of phFSH. Lower concentrations of phFSH resulted in a gradual shift from inhibition to a biphasic activity in the presence of the ED20 of phFSH. Biphasic responses to BV-hFSH were attributed to activation of different G protein subtypes, since treatment of 3D2 cells with cholera toxin or pertussis toxin differentially blocked the two phases of BV-hFSH bioactivity. These data suggest that alternative glycosylation of FSH leads to a functionally altered form of the hormone. Functionally different hormones appear to convey distinct signals that are transduced by the receptor-transduction system as either stimulatory or inhibitory intracellular events via promiscuous, glycosylation-dependent G protein coupling. Promiscuity in signaling of the FSH receptor, in turn, may represent a potentially novel mechanism for FSH action, whereby the gonad may respond in diverse ways to complex hormonal signals such as those presented by circulating FSH isoforms.

Paclitaxel and concurrent radiation for locally advanced pancreatic and gastric cancer: a phase I study

PURPOSE

To determine the maximum-tolerated dose (MTD), dose-limiting toxicities, and potential antitumor activity of weekly paclitaxel with concurrent radiation (RT) for locally advanced pancreatic and gastric cancer.

PATIENTS AND METHODS

Thirty-four patients with locally advanced adenocarcinoma of the pancreas or stomach were studied. The initial dose of paclitaxel was 30 mg/m2 by 3-hour intravenous (I.V.) infusion repeated every week for 6 weeks with 50 Gy RT. Doses were escalated at 10-mg/m2 increments in successive cohorts of three new patients until dose-limiting toxicity was observed.

RESULTS

The dose-limiting toxicities at 60 mg/m2/wk were abdominal pain within the RT field, nausea, and anorexia. Of 23 patients with assessable disease, 11 (seven with gastric, four with pancreatic cancer) had objective responses for an overall response rate of 48%.

CONCLUSION

Concurrent paclitaxel with upper abdominal RT is well tolerated at dosages that have substantial activity. A phase II trial of neoadjuvant paclitaxel and RT at the MTD of 50 mg/m2/wk is underway.

Efficacy of mycophenolate mofetil in the treatment of chronic graft-versus-host disease

Current treatment of chronic graft-versus-host disease (cGVHD) with prednisone (PSE) alone or with added cyclosporine or tacrolimus still has a very high failure and complication rate, and new treatment approaches are needed for both primary and salvage therapy. Mycophenolate mofetil (MMF) is an immunosuppressive agent currently in use for acute graft-versus-host disease prophylaxis. To determine whether MMF had activity in the treatment of cGVHD, we added MMF to standard cyclosporine, tacrolimus, and/or PSE as salvage/second-line (n = 24) or first-line (n = 10) therapy in 34 patients. Nine (90%) of 10 patients receiving first-line and 18 (75%) of 24 receiving second-line MMF therapy responded. Twelve (35%) patients had a complete remission, 15 (44%) had a partial remission, 5 (15%) had stable disease, and only 2 (6%) had progressive disease. Out of 30 patients receiving PSE, 22 (73%) were able to decrease PSE doses (median decrease of 50%; range, 25%-100%). With a median follow-up of 24 months (range, 6-28 months), 29 (85%) patients are alive. Three patients had to discontinue MMF because of abdominal cramps within 3 months of starting treatment. These data suggest that MMF is an active, well-tolerated agent in the treatment of cGVHD and may have a beneficial effect on the survival of patients with this complication.

Ordered stacking fault arrays in silicon nanowires

Correlated Raman microscopy and transmission electron microscopy were used to study the ordering of {111} planar defects in individual silicon nanowires. Detailed electron diffraction and polarization-dependent Raman analysis of individual nanowires enabled assessments of the stacking fault distribution, which varied from random to periodic, with the latter giving rise to local domains of 2H and 9R polytypes rather than the 3C diamond cubic structure. Some controversies and inconsistencies concerning earlier reports of polytypes in Si nanowires were resolved.