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PubMed2000

Activity and toxicity of GI147211 in breast, colorectal and non-small-cell lung cancer patients: an EORTC-ECSG phase II clinical study.

BACKGROUND: GI147211 is a water-soluble synthetic analogue of camptothecin showing promising in vivo and in vitro antitumor activity and an acceptable toxicity profile. PATIENTS AND METHODS: Between April 1995 and November 1996, 67 eligible patients with pretreated breast cancer (25 patients) and chemo-naïve colorectal (19 patients) and non-small-cell lung cancer (23 patients) were entered into three multicentric, non-randomized phase II trials. Treatment schedule consisted of intravenous GI1147211 administered at a dose of 1.2 mg/m2/day for five consecutive days every three weeks. RESULTS: Hematological toxicity was common with grade 3-4 neutropenia in 54% of patients and neutropenic fever together or not associated with infection in 14.5% of patients. Grade 3-4 thrombocytopenia and grade 2-4 anemia were observed in 20% and in 68% of patients, respectively. Non-hematological toxicity was generally mild to moderate and consisted mainly of gastrointestinal toxicity, asthenia and alopecia. A dose-escalation to 1.5 mg/m2/d was feasible in 17 (25%) patients. The antitumor activity of GI1147211 was moderate in breast cancer patients (3 partial responses (PRs), response rate (RR) 13%) and minimal in non-small cell lung cancer patients (2 PRs, RR 9%). No objective responses were obtained in colorectal patients. CONCLUSIONS: GI147211, at the dose and schedule employed in this study, showed an acceptable safety profile but a modest antitumor activity in the examined tumor types.

Adult↗
PubMed2000

Octreotide acetate long-acting release in patients with metastatic neuroendocrine tumors pretreated with lanreotide.

BACKGROUND: In the present study we investigated the efficacy and tolerability of i.m. octreotide acetate (octreotide LAR) in patients with metastatic neuroendocrine tumors (NETs) previously treated and failed on i.m. lanreotide. PATIENTS AND METHODS: Fifteen patients (8 females, 7 males, median age 67 years, range 28-81 years) with metastatic NETs (8 endocrine pancreatic tumors, 7 midgut carcinoids) were enrolled in the study. All patients were in progressive disease (objective: 11 patients, symptomatic: 10 patients, biochemical: 11 patients) after treatment with slow release lanreotide, 30 mg every 14 days for a median time of 8 months (range 3-19 months). All patients had measurable disease; 12 patients had elevated serum and/or urine markers and 11 were symptomatic. Octreotide scintigraphy was positive in 13 of 15 patients. Octreotide LAR was administered as i.m. injection at the dose of 20 mg every four weeks until disease progression. RESULTS: An objective partial response (PR) was documented in one patient (7%), no change (NC) in six (40%), and progressive disease (PD) in eight patients (53%). The PR was observed in one patient with non-functioning endocrine pancreatic tumor with progressive liver and lymph node metastases after 16 months of i.m. lanreotide therapy. The median duration of disease stabilization was 7.5 months (range 6-12+ months). The overall biochemical response rate was 41%, including CRs (33%) and PRs (8%); biochemical responses were observed in carcinoids as well as in endocrine pancreatic tumors; the median duration of response was 5 months for CRs and 7.5 months for PRs. The overall symptomatic response rate was 82%. The median duration of response for diarrhoea, abdominal pain, or both was 6.5 months (range 3-12+ months). Improvement in performance status (PS) was obtained in 5 of 11 patients with PS of 1 at study entry. Median duration of octreotide LAR treatment was seven months (range 3-12+ months). No serious adverse events were reported; mild side effects were reported in 26% of patients. CONCLUSIONS: Octreotide LAR 20 mg shows significant efficacy in terms of objective response rate (PR + SD), biochemical and symptomatic control in patients with metastatic NETs of the GEP system pretreated and progressing on slow release lanreotide.

Adult↗
PubMed1998

A phase I-II study of bi-weekly paclitaxel as first-line treatment in metastatic breast cancer.

BACKGROUND: Single-agent bi-weekly paclitaxel was studied as first-line metastatic treatment for breast cancer in a phase I-II trial. PATIENTS AND METHODS: Thirty-eight women with metastatic breast cancer were enrolled. Thirty-seven are evaluable for toxicity, 35 for response. RESULTS: The MTD was defined at 160 mg/m2 q two weeks with dose limiting toxicity in two patients consisting of hematological toxicity (1) and neurotoxicity (2). Twenty patients were treated at 150 mg/m2, the recommended dose. Response rates were two CRs and nine PRs (overall 61%) at the RD of 150 mg/m2 and three CRs and 11 PRs for an overall RR of 67% for the two top doses. CONCLUSIONS: The good drug tolerance, response rates, and convenience over weekly treatment suggest this may be a worthwhile regimen.

Adult↗
PubMed2001

Decennial trends of social differentials in smoking habits in Italy.

OBJECTIVE: To present social trends of smoking habits in Italy during the period 1980-1994. METHODS: Data from five national health surveys (1980, 1983, 1986-1987, 1990-1991, 1994) were analyzed in order to calculate smoking prevalences. Education attained was used as social class indicator. MAIN MEASURES: SDPs (prevalence rate standardized on the 1981 Italian population) and PRs (prevalence ratios primary school/degree). Confidence intervals and p-values were calculated as indicators of statistical significance. RESULTS: Among men SDP decreased from 59.5% in 1980 to 37.3% in 1994 and PRs for social classes varied from 1.21 in 1980 to 1.47 in 1994. Corresponding results for women were 17.9% to 20.0% and 0.36 to 0.73. CONCLUSIONS: Lower-educated men smoke more than those in higher social categories, and data collected during 1980-1994 in Italy show a tendency to increase such differentials. Among women this pattern was the opposite in 1980, with a tendency to reduce differences over time. Therefore, for both genders data show a progressive disadvantage for the low-educated categories. The greater compliance of better-educated groups with anti-smoking interventions must be taken into account, and should suggest "unequal" interventions that can be more effective among disadvantaged social groups.

Adolescent↗
PubMed2003

Autism-related language, personality, and cognition in people with absolute pitch: results of a preliminary study.

Reports of a relatively high prevalence of absolute pitch (AP) in autistic disorder suggest that AP is associated with some of the distinctive cognitive and social characteristics seen in autism spectrum disorders. Accordingly we examined cognition, personality, social behavior, and language in 13 musicians with strictly defined AP (APS) and 33 musician controls (MC) without AP using standardized interviews and tests previously applied to identify the broad autism phenotype seen in the relatives of autistic probands. These included the Pragmatic Rating Scale (PRS) (social aspects of language) the Personality Assessment Schedule (PAS) (rigidity, aloofness, anxiety/worry, hypersensitivity), and WAIS performance subtests (PIQ). On the basis of their behavior in the interviews, subjects were classified as socially eccentric, somewhat eccentric, or not eccentric. Forty-six percent of the APS, but only 15% of the MC, were classified as socially eccentric (p < .03). APS but not MC showed higher scores on block design than on the other PIQ tests (p < .06), a PIQ pattern seen in autism spectrum disorders. Although APS and MC did not differ significantly on other measures it is of note that APS mean scores on the PRS and PAS (5.69, 4.92) were almost twice as high as those for the MC (3.03, 2.45). Thus, musicians with AP show some of the personality, language, and cognitive features associated with autism. Piecemeal information processing, of which AP is an extreme and rare example, is characteristic of autism and may be associated as well with subclinical variants in language and behavior. We speculate that the gene or genes that underlie AP may be among the genes that contribute to autism.

Adolescent↗
PubMed2003

The DNA-B of the non-phloem-limited bean dwarf mosaic virus (BDMV) is able to move the phloem-limited Abutilon mosaic virus (AbMV) out of the phloem, but DNA-B of AbMV is unable to confine BDMV to the phloem.

Abutilon mosaic virus (AbMV) and bean dwarf mosaic virus (BDMV) are two phylogenetically related bipartite begomoviruses. While AbMV is restricted to phloem, BDMV spreads to non-phloem tissues. Cell-to-cell and long-distance movement of AbMV and BDMV were investigated after replacing the coat protein (CP) gene with the reporter gene encoding the green fluorescence protein (GFP). The DNA-A and DNA-B genomic components of AbMV and BDMV, and their pseudorecombinants (PR), were delivered to bean (Phaseolus vulgaris) seedlings and detached leaves with DNA-coated microprojectiles. Virus-associated fluorescence was observed with the confocal microscope. Delivery of AbMV and BDMV GFP reporters showed that the epidermal tissue was the main recipient of the viral DNA; the DNA-A of the two viruses was unable to move out of the recipient cells. AbMV DNA-A co-inoculated with AbMV DNA-B did not move from cell to cell in the epidermis and did not reach the phloem. However, co-inoculation of AbMV DNA-A with BDMV DNA-B resulted in PR cell-to-cell movement out of the epidermis and long-distance movement in the phloem. In contrast, BDMV DNA-A moved from cell to cell and over a long distance when co-inoculated with either its own DNA-B or with the DNA-B of AbMV. Thus, the DNA-B of the non-phloem-limited BDMV overcame the phloem limitation of AbMV. In the reciprocal case, the DNA-B of the phloem-limited AbMV did not confine the non-phloem limited BDMV to the phloem. Hence, we assume that the DNA-A component of BDMV includes determinants involved in the movement pattern of the virus in addition to the DNA-B-encoded BC1 and BV1 which have previously been shown to be involved in virus movement. The results also confirm that the CP is not necessary for virus movement; however, replacing the CP of AbMV and BDMV with GFP resulted in a decrease in symptom severity. DNA-B was involved in symptom severity; the B component of BDMV produced symptoms more severe than those induced by that of AbMV, whether in wild-type PRs or in PRs with CP-GFP replacement. It is interesting to note that when the GFP gene under the control of the CaMV 35S promoter (35S-GFP) was delivered to the bean tissue, with or without the DNA-B component of BDMV, GFP was expressed but did not move from cell to cell. However, when the 35S-GFP was delivered together with BDMV DNA-A and DNA-B, GFP showed cell-to-cell movement in the epidermis but was restricted to these cells. Hence, infection of cells with a functional bipartite begomovirus may facilitate cell-to-cell movement of macromolecules.

Biolistics↗
PubMed1990

Oral tegafur in the treatment of gastrointestinal tract cancers: a phase II study.

Fifty patients affected by histologically confirmed gastrointestinal tract cancer (GTC) were treated with oral tegafur (TG) 1,000 mg m-2 p.o. on days 1-14 repeated after a 14 day interval. Out of 42 evaluable patients seven patients had a partial response (PR. 17%) with a median duration of 20.5 weeks, three had a minimal response (7%) with a median duration of 23.7 weeks, nine showed a stabilisation which lasted a median of 31.3 weeks, and 23 progressed (55%). No response was obtained in patients affected by carcinoma of the pancreas and the hepatobiliary system. All PRs were achieved in patients with metastatic disease to the liver. No response was seen in patients with bone, lung or nodal metastasis. Three PRs were obtained in patients resistant to 5-fluorouracil. The difference in survival between patients who achieved PR and those who had a stabilisation was not statistically significant. On the other hand the survival of patients with PR was significantly longer than that of patients who progressed. Oral TG was well tolerated by most patients. WHO grade 1-2 gastrointestinal and neurological toxicities were seen respectively in 36% and 25% of cases. Five patients had grade 3 nausea/vomiting and one had grade 3 diarrhoea. Our data suggest that oral TG is effective in the treatment of stomach and colorectal cancers.

Administration, Oral↗
PubMed1995

EORTC (30885) randomised phase III study with recombinant interferon alpha and recombinant interferon alpha and gamma in patients with advanced renal cell carcinoma. The EORTC Genitourinary Group.

In the treatment of renal cell carcinoma both complete (CRs) and partial remissions (PRs) have been obtained using recombinant (r) interferon alpha (IFN-alpha), with response rates ranging from 0 to 31% (mean 16%). rIFN-gamma is a potent immunostimulating agent, but the clinical experience of its use is limited and results are conflicting. In a phase II study with the combination of rIFN-alpha 2c (Boehringer Ingelheim) and rIFN-gamma (Genentech, supplied by Boehringer Ingelheim) in 31 eligible patients, a response rate of 25% was recorded. Based on this observation a randomised phase III study was initiated to investigate the possible advantage of the addition rIFN-gamma to rIFN-alpha 2c treatment. Treatment consisted of rIFN-alpha 2c 30 micrograms m-2 = 10 x 10(6) IU m-2 s.c. twice weekly in arm A and the same dose of rIFN-alpha combined with rIFN-gamma 100 micrograms m-2 = 2 x 10(6) IU m-2 in arm B. Eligibility criteria included documented progression of disease; patients with bone lesions only and overt central nervous system metastases were excluded. Between November 1988 and September 1990, 102 patients were entered into the study. An interim analysis showed a response in 7/53 (13%) patients (two CRs and five PRs) in the rIFN-alpha 2c monotherapy arm and in 2/45 (4%) (one CR and one PR) patients in the combination arm. This difference was not statistically significant (P = 0.17). The probability of missing an eventual 10% advantage for the combination is 0.001. The numbers are insufficient to rule out a negative effect of the addition of rIFN-gamma. The dose intensity of IFN-alpha 2c for the two treatment arms was the same. The addition of rIFN-gamma does not improve the response rate of rIFN-alpha 2c monotherapy. A possible detrimental effect cannot be excluded.

Adult↗
PubMed1997

A phase I/II study of leucovorin, carboplatin and 5-fluorouracil (LCF) in patients with carcinoma of unknown primary site or advanced oesophagogastric/pancreatic adenocarcinomas.

Carcinoma of unknown primary site (CUPS) accounts for 5-10% of all malignancies. Forty patients with metastatic CUPS or advanced oesophagogastric/pancreatic adenocarcinomas were recruited. Eligibility included ECOG performance status 0-2, minimum life expectancy of 3 months and measurable disease. The regimen consisted of bolus intravenous 5 fluorouracil (5-FU) and leucovorin (20 mg m-2) days 1-5 and carboplatin (AUC5) on day 3. The leucovorin/carboplatin/5-FU (LCF) was repeated every 4 weeks. The starting dose of 5-FU was 350 mg m-2 day-1 with escalation to 370 and then 400 mg m-2 day -1 after the toxicity at the previous level had been assessed. The maximum tolerated dose (MTD) was defined as the dosage of 5-FU that achieved 60% grade 3/4 toxicity. In addition, objective and symptomatic responses, quality of life and survival were assessed. The MTD of 5-FU in the LCF regimen was 370 mg m-2. The predominant toxicity was asymptomatic marrow toxicity. The 350 mg m-2 level was then expanded. There were two toxic deaths due to neutropenic sepsis, one at 370 mg m-2 after one course and one at 350 mg m-2 after four courses. The objective response rate was 25% with one complete response (CR) and nine partial responses (PRs). The median duration of response was 3.4 months (range 1-10). The CR and eight of the nine PRs were in CUPS patients. Twelve patients developed progressive disease on LCF. Median survival for all 40 patients was 7.8 months (10 months median survival for those treated at 350 mg m-2). The majority of patients described a symptomatic improvement with LCF chemotherapy. The recommended dose of 5-FU for future studies is 350 mg m-2 combined with leucovorin 20 mg m-2 and carboplatin (AUC5).

Adenocarcinoma↗
PubMed2004

Crystal structure of Dcp1p and its functional implications in mRNA decapping.

A major pathway of eukaryotic mRNA turnover begins with deadenylation, followed by decapping and 5'-->3' exonucleolytic degradation. A critical step in this pathway is decapping, which is carried out by an enzyme composed of Dcp1p and Dcp2p. The crystal structure of Dcp1p shows that it markedly resembles the EVH1 family of protein domains. Comparison of the proline-rich sequence (PRS)-binding sites in this family of proteins with Dcp1p indicates that it belongs to a novel class of EVH1 domains. Mapping of the sequence conservation on the molecular surface of Dcp1p reveals two prominent sites. One of these is required for the function of the Dcp1p-Dcp2p complex, and the other, corresponding to the PRS-binding site of EVH1 domains, is probably a binding site for decapping regulatory proteins. Moreover, a conserved hydrophobic patch is shown to be critical for decapping.

Amino Acid Sequence↗
PubMed2026

Integrating biological pathway polygenic scores and trauma in psychosis: findings from the EU-GEI study.

Psychotic disorders are complex, multifactorial conditions influenced by both genetic liability and early environmental adversity. Polygenic risk scores (PRSs) derived from genome-wide association studies have shown utility in capturing genetic predisposition, but their biological interpretability remains limited. In this study, we evaluated whether biologically informed pathway-specific polygenic scores (pPGSs) for psychosis, restricted to neurotransmitter-related pathways, could help clarify gene-environment interplay. Using data from 1 192 individuals in the EU-GEI multi-site case-control study, we constructed pPGSs for dopamine, glutamate, GABA, and serotonin systems. We investigated associations between pPGSs and childhood trauma (rGE), their interactions on psychosis risk (GxE), and the influence of the genome-wide psychosis PRS on these relationships. Serotonin, dopamine, and glutamate pPGSs were positively associated with a composite trauma exposure (i.e., abuse and neglect), suggesting shared genetic factors contributing to both psychosis liability and early adversity. Significant negative GxE effects were observed for both dopamine and serotonin pPGSs, indicating that higher trauma exposure diminished the relative influence of genetic liability on psychosis risk. Adjustment for the genome-wide psychosis PRS attenuated most effects, but serotonergic and dopaminergic associations remained robust, supporting pathway-specific contributions beyond general polygenic risk. These findings provide proof-of-concept for the utility of pPGSs in psychiatric research, suggesting both genetic contributions to trauma exposure and GxE effects on psychosis risk. Further research incorporating epigenetic data and longitudinal designs may enhance mechanistic insight and translational potential.

Adult↗
PubMed2025

Clinical implications of bone marrow adiposity identified by phenome-wide association and Mendelian randomization in the UK Biobank.

Bone marrow adiposity changes in diverse diseases, but the full scope of these, and whether they are directly influenced by marrow adiposity, remains unknown. To address this, we previously measured the bone marrow fat fraction of the femoral head, total hip, femoral diaphysis, and spine of over 48,000 UK Biobank participants. Here, we first use these data for PheWAS to identify diseases associated with marrow adiposity at each site. This reveals associations with 47 incident diseases across 12 disease categories, including osteoporosis, fracture, type 2 diabetes, cardiovascular diseases, cancers, and other conditions that burden public health worldwide. Intriguingly, type 2 diabetes associates positively with spine bone marrow adiposity but negatively with marrow adiposity at femoral sites. We then establish PRSs based on bone-marrow-fat-fraction-associated SNPs and use PRS-PheWAS and Mendelian randomization to explore causal associations between marrow adiposity and disease. PRS-PheWAS reveals that genetic predisposition to increased marrow adiposity is positively associated with osteoporosis and fractures. Mendelian randomization further suggests that increased marrow adiposity at the diaphysis and total hip is causally associated with osteoporosis. Our findings substantially advance understanding of how marrow adiposity impacts human health and highlight its potential as a biomarker and/or therapeutic target for diverse human diseases.

Humans↗
PubMed2003

Neoadjuvant systemic fluorouracil and mitomycin C prior to synchronous chemoradiation is an effective strategy in locally advanced rectal cancer.

This study was designed to evaluate the benefits of neoadjuvant chemotherapy prior to chemoradiation and surgery in patients with locally advanced rectal cancer. Patients with previously untreated primary rectal cancer, reviewed in a multidisciplinary meeting and considered to have locally advanced disease on the basis of physical examination and imaging (MRI+CT n=30, CT alone n=6), were recruited. Patients received protracted venous infusion 5-FU (300 mg m(-2) day(-1) for 12 weeks) with mitomycin C (MMC) (7 mg m(-2) i.v. bolus every 6 weeks). Starting on week 13, 5-FU was reduced to 200 mg m(-2) day(-1) and concomitant pelvic radiotherapy 45 Gy in 25 fractions was commenced followed by 5.4-9 Gy boost to tumour bed. Surgery was planned 6 weeks after chemoradiation. Postoperatively, patients received 12 weeks of MMC and 5-FU at the same preoperative doses. Between January 99 and August 01, 36 eligible patients were recruited. Median age was 63 years (range=40-85). Following neoadjuvant chemotherapy, radiological tumour response was 27.8% (one CR and nine PRs) and no patient had progressive disease. In addition, 65% of patients had a symptomatic response including improvement in diarrhoea/constipation (59%), reduced rectal bleeding (60%) and diminished pelvic pain/tenesmus (78%). Following chemoradiation, tumour regression occurred in 80.6% (six CRs and 23 PRs; 95% CI=64-91.8%) and only one patient still had an inoperable tumour. R0 resection was achieved in 28 patients (82%). When compared with initial clinical staging, the pathological downstaging rate in T and/or N stage was 73.5% and pathological CR was found in one patient. Neoadjuvant systemic chemotherapy as a prelude to synchronous chemoradiation can be administered with negligible risk of disease progression and produces considerable symptomatic response with associated tumour regression.

Adult↗
PubMed2004

Phase I dose-escalation trial of irinotecan with continuous infusion 5-FU first line, in metastatic colorectal cancer.

This single-centre phase I trial was designed to determine the maximum tolerated dose of irinotecan and the recommended dose to use in combination with a fixed dose of 5-fluorouracil (5-FU) administered as a protracted venous infusion, for the first-line treatment of metastatic colorectal cancer (CRC). Tolerability and efficacy were secondary end points. In all, 22 patients, median age 57 years, were treated with escalating, weekly doses of irinotecan (50, 75, 100 and 85 mg m(-2)) in combination with 250 mg m(-2) 5-FU administered as a continuous infusion. All patients had measurable disease. The combination was well tolerated up to an irinotecan dose of 75 mg m(-2). However, three out of five patients at the 100 mg m(-2) irinotecan dose level had their dose reduced due to multiple grade 2 toxicities, and eventually one patient stopped treatment due to grade 3 diarrhoea and multiple grade 2 toxicities. Subsequent patients were recruited at an irinotecan dose level of 85 mg m(-2). The overall response rate was 55%, comprising one complete and 11 partial responses (PRs). Six patients also achieved sustained stable disease (SD), giving a clinical benefit (complete response/PR/SD) response of 82%. The median duration of response was 238 days (8.5 months) and median time to progression was 224 days (8.0 months). Two patients who achieved PRs underwent partial hepatectomies. Thus, irinotecan (85 mg m(-2)) combined with a continuous infusion of 5-FU (250 mg m(-2)) is an active and well-tolerated regimen for the treatment of metastatic CRC. It represents an effective treatment for patients who require close supervision and support, throughout their initial exposure to chemotherapy for this disease, and this dose combination was recommended for an ongoing phase II study.

Adult↗
PubMed2004

Cholinergic facilitation of erection and ejaculation in spinal cord-transected rats.

Penile reflexes (PRs) were monitored in chronic spinal cord-transected rats by identifying them visually, and at the same time they were recorded as the electromyographic activity of bulbospongiosus muscles. Intraperitoneal injection of the agonist muscarine (10 microg) produced a facilitation of PRs. A decrease in the latency, an increase in the number of clusters and often an increase in the duration of cups were found after muscarine. In addition, 66% (six out of nine) of the animals ejaculated after muscarine. These results suggest that cholinergic receptor stimulation may be involved in erectile and ejaculatory mechanisms mediated by the spinal cord.

Animals↗
PubMed2005

Estrogen-induced loss of progesterone receptor expression in normal and malignant ovarian surface epithelial cells.

While estrogens are suspected risk factors for epithelial ovarian cancer (OCa), progesterone (P4) has been shown to exert protective effects. The biological actions of P4 in target cells are mediated by progesterone receptors (PRs) that exist principally as A- and B-isoforms. We observed overexpression of PR-A and PR-B protein in two lines of OCa cells when compared to two lines of nontumorigenic, normal human ovarian surface epithelial (HOSE) cells. Treatment of HOSE or OCa cells with estrone or 17beta-estradiol at 10(-8) M for a period of 72 h induced significant loss of PR-A and PR-B mRNA and protein expression, with the regulation primarily controlled at the transcriptional level. In contrast, breast cancer cells (line MCF-7) exposed to estrogens upregulated PR-A and PR-B expression. Of significance, both the inhibitory and stimulatory actions of estrogens were blocked by the specific ER-antagonist ICI 182,780 (ICI, 10(-5) M), confirming estrogen specificity. Co-treatment of estrogen-exposed HOSE, OCa, and MCF-7 cell lines with inhibitors of type 1- and type 2-17beta hydroxysteroid dehydrogenase did not affect the previously observed changes in PR expression, suggesting that the action of each estrogen is direct and not mediated via conversion to its metabolic counterpart. Green fluorescence protein (GFP)-PR-A and GFP-PR-B were localized in the cytoplasmic compartment of untreated HOSE cells and translocated to the nucleus after P4 treatment, while both chimera PRs resided in the nuclei of OCa cells in a ligand-independent manner. In OCa cell cultures, P4 (10(-6) M), but not RU486 (10(-5) M), induced apoptosis that was blocked by co-treatment with the antiprogestin but enhanced by co-treatment with ICI. In sharp contrast, P4 induced proliferation, while ICI and RU486 caused cell death in MCF-7 cells. In conclusion, this study is first to demonstrate estrogens as negative regulators of PR expression in HOSE/OCa cells and to provide a mechanistic basis upon which to explain the antagonism of estrogens on the anti-OCa action of progestins. It also raises the possibility of using progestin and ICI as a combinational therapy for OCa treatment.

Adult↗
PubMed2007

Crystal structure of human phosphoribosylpyrophosphate synthetase 1 reveals a novel allosteric site.

PRPP (phosphoribosylpyrophosphate) is an important metabolite essential for nucleotide synthesis and PRS (PRPP synthetase) catalyses synthesis of PRPP from R5P (ribose 5-phosphate) and ATP. The enzymatic activity of PRS is regulated by phosphate ions, divalent metal cations and ADP. In the present study we report the crystal structures of recombinant human PRS1 in complexes with SO4(2-) ions alone and with ATP, Cd2+ and SO4(2-) ions respectively. The AMP moiety of ATP binds at the ATP-binding site, and a Cd2+ ion binds at the active site and in a position to interact with the beta- and gamma-phosphates of ATP. A SO4(2-) ion, an analogue of the activator phosphate, was found to bind at both the R5P-binding site and the allosteric site defined previously. In addi-tion, an extra SO4(2-) binds at a site at the dimer interface between the ATP-binding site and the allosteric site. Binding of this SO4(2-) stabilizes the conformation of the flexible loop at the active site, leading to the formation of the active, open conformation which is essential for binding of ATP and initiation of the catalytic reaction. This is the first time that structural stabilization at the active site caused by binding of an activator has been observed. Structural and biochemical data show that mutations of some residues at this site influence the binding of SO4(2-) and affect the enzymatic activity. The results in the present paper suggest that this new SO4(2-)-binding site is a second allosteric site to regulate the enzymatic activity which might also exist in other eukaryotic PRSs (except plant PRSs of class II), but not in bacterial PRSs.

Allosteric Site↗
PubMed2001

A dual path programmable array microscope (PAM): simultaneous acquisition of conjugate and non-conjugate images.

A programmable array microscope (PAM) incorporates a spatial light modulator (SLM) placed in the primary image plane of a widefield microscope, where it is used to define patterns of illumination and/or detection. We describe the characteristics of a special type of PAM collecting two images simultaneously. The conjugate image (Ic) is formed by light originating from the object plane and returning along the optical path of the illumination light. The non-conjugate image (Inc) receives light from only those regions of the SLM that are not used for illuminating the sample. The dual-signal PAM provides much more time-efficient excitation than the confocal laser scanning microscope (CLSM) and greater utilization of the available emission light. It has superior noise characteristics in comparison to single-sided instruments. The axial responses of the system under a variety of conditions were measured and the behaviour of the novel Inc image characterized. As in systems in which only Ic images are collected (Nipkow-disc microscopes, and previously characterized PAMs), the axial response to thin fluorescent films showed a sharpening of the axial response as the unit cell of the repetitive patterns decreased in size. The dual-signal PAM can be adapted to a wide range of data analysis and collection strategies. We investigated systematically the effects of patterns and unit cell dimensions on the axial response. Sufficiently sparse patterns lead to an Ic image formed by the superposition of the many parallel beams, each of which is equivalent to the single scanning spot of a CLSM. The sectioning capabilities of the system, as given by its axial responses, were similar for a given scan pattern and for processed pseudorandom sequence (PRS) scans with the same size of the unit cell. For the PRS scans, optical sectioning was achieved by a subtraction of an Inc image or, alternatively, a scaled widefield image from the Ic image. Based on the comparative noise levels of the two methods, the non-conjugate subtraction was significantly superior. A point spread function for Ic and Inc was simulated and properties of the optical transfer functions (OTFs) were compared. Simulations of the OTF in non-conjugate imaging did not suffer from the missing cone problem, enabling a high quality deconvolution of the non-conjugate side alone. We also investigated the properties of images obtained by subjecting the Ic and Inc data to a combined maximum likelihood deconvolution.

Animals↗