Does using anatomical models improve patient satisfaction in orthopaedic consenting? Single-blinded randomised controlled trial.

BACKGROUND: Patient satisfaction in consenting is a major pillar of clinical governance and healthcare quality assessment. The purpose was to observe the effect of using 3D anatomical models of knee and shoulder joints on patient satisfaction during informed consent in the largest single-blinded randomised controlled trial in this field. METHODS: 52 patients undergoing elective knee or shoulder surgery were randomised into two groups when being consented. The intervention group (n = 26) was shown an anatomical model of the knee/shoulder joint while the control group (n = 26) was given only a verbal explanation without a model. Patients rated their satisfaction on the validated Medical Interview Satisfaction Scale (MISS-26) questionnaire. Semi-structured interviews were analysed for specific themes to determine key factors that influenced patient satisfaction. The mean score ±SD were calculated with significance set at p < 0.05. RESULTS: There was a significant difference in the overall satisfaction between the control and intervention cohorts (MISS-26 score 4.33 [86.6%] ± 0.646 vs 4.70 [94.0%] ± 0.335 respectively, 7.4% improvement, 8.5% difference, p = 0.01). Behavioural criteria showed a 13% increase in satisfaction (p = 0.02). Semi-structured interviews determined that the factors influencing satisfaction included the surgeon's interpersonal manner, the use of the visual aid and seeing the consultant surgeon in clinic. All patients in the intervention cohort identified factors contributing to their satisfaction, whereas a fifth of the control cohort claimed nothing at all made them feel satisfied. CONCLUSION: Anatomical models as visual aids significantly increased patient satisfaction during the consenting process and played an integral part of the surgeon's explanation. Patients exposed to anatomical models also claimed to be more satisfied with the surgeon's inter-personal skills. This study recommends the use of anatomical models, which are both cost-effective and easily implementable, during explanation and consent for orthopaedic procedures.

NF-kappa B-like factors mediate interleukin 1 induction of c-myc gene transcription in fibroblasts.

Interleukin 1 (IL-1) is a pluripotent cytokine involved in mediating a variety of physiological processes, including induction of cell proliferation upon wound healing. Treatment of quiescent FS-4 human dermal fibroblast cells with IL-1 activates c-myc gene transcription, and nuclear localization of NF-kappa B. Previously, we have noted that the murine c-myc gene contains two functional NF-kappa B sites located at -1101 to -1081 bp (upstream regulatory element [URE]) and +440 to +459 bp (internal regulatory element [IRE]) relative to the P1 promoter. Here we have demonstrated that IL-1 treatment induced binding of NF-kappa B-like proteins (p50/p65) to these c-myc elements. Heterologous promoter-CAT constructs driven by multiple copies of either the URE or IRE were IL-1 inducible when transfected into FS-4 cells. In contrast, constructs harboring elements with two G to C residue conversions, such that they were no longer able to bind NF-kappa B, were not responsive to IL-1. Mutation of these two base pairs at both NF-kappa B sites within a c-myc promoter/exon I-CAT construct, resulted in loss of inducibility with IL-1 upon transfection into quiescent FS-4 cells. Thus, IL-1 significantly induces c-myc expression through positive regulation by NF-kappa B, suggesting a role for this family of factors in activation of proliferation associated with wound healing.

Inhibition of myogenic bHLH and MEF2 transcription factors by the bHLH protein Twist.

The myogenic basic helix-loop-helix (bHLH) and MEF2 transcription factors are expressed in the myotome of developing somites and cooperatively activate skeletal muscle gene expression. The bHLH protein Twist is expressed throughout the epithelial somite and is subsequently excluded from the myotome. Ectopically expressed mouse Twist (Mtwist) was shown to inhibit myogenesis by blocking DNA binding by MyoD, by titrating E proteins, and by inhibiting trans-activation by MEF2. For inhibition of MEF2, Mtwist required heterodimerization with E proteins and an intact basic domain and carboxyl-terminus. Thus, Mtwist inhibits both families of myogenic regulators and may regulate myotome formation temporally or spatially.

Inhibition of myogenic differentiation in proliferating myoblasts by cyclin D1-dependent kinase.

Although the myogenic regulator MyoD is expressed in proliferating myoblasts, differentiation of these cells is limited to the G0 phase of the cell cycle. Forced expression of cyclin D1, but not cyclins A, B, or E, inhibited the ability of MyoD to transactivate muscle-specific genes and correlated with phosphorylation of MyoD. Transfection of myoblasts with cyclin-dependent kinase (Cdk) inhibitors p21 and p16 augmented muscle-specific gene expression in cells maintained in high concentrations of serum, suggesting that an active cyclin-Cdk complex suppresses MyoD function in proliferating cells.

Correlation of terminal cell cycle arrest of skeletal muscle with induction of p21 by MyoD.

Skeletal muscle differentiation entails the coordination of muscle-specific gene expression and terminal withdrawal from the cell cycle. This cell cycle arrest in the G0 phase requires the retinoblastoma tumor suppressor protein (Rb). The function of Rb is negatively regulated by cyclin-dependent kinases (Cdks), which are controlled by Cdk inhibitors. Expression of MyoD, a skeletal muscle-specific transcriptional regulator, activated the expression of the Cdk inhibitor p21 during differentiation of murine myocytes and in nonmyogenic cells. MyoD-mediated induction of p21 did not require the tumor suppressor protein p53 and correlated with cell cycle withdrawal. Thus, MyoD may induce terminal cell cycle arrest during skeletal muscle differentiation by increasing the expression of p21.

pRb is required for MEF2-dependent gene expression as well as cell-cycle arrest during skeletal muscle differentiation.

BACKGROUND: The onset of differentiation-specific gene expression in skeletal muscle is coupled to permanent withdrawal from the cell cycle. The retinoblastoma tumor-suppressor protein (pRb) is a critical regulator of this process, required for both cell-cycle arrest in G0 phase and high-level expression of late muscle-differentiation markers. Although the cell-cycle defects that are seen in pRb-deficient myocytes can be explained by the well-described function of pRb as a negative regulator of the transition from G1 to S phase, it remains unclear how pRb positively affects late muscle-gene expression. RESULTS: Here, we show that the myogenic defect in Rb-/- cells corresponds to a deficiency in the activity of the transcription factor MEF2. Without pRb, MyoD induces the accumulation of nuclear-localized MEF2 that is competent to bind DNA yet transcriptionally inert. When pRb is present, MyoD stimulates the function of the MEF2C transcriptional activation domain and the activity of endogenous MEF2-type factors. Co-transfection of MyoD together with an activated form of MEF2C containing the Herpesvirus VP16 transcriptional activation domain partially bypasses the requirement for pRb and induces late muscle-gene expression in replicating cells. This ectopic myogenesis is nevertheless significantly augmented by co-expression of an E2F1-pRb chimeric protein that blocks the cell cycle. CONCLUSION: These findings indicate that pRb promotes the expression of late-stage muscle-differentiation markers by both inhibiting cell-cycle progression and cooperating with MyoD to promote the transcriptional activation activity of MEF2.

An antisense promoter of the murine c-myc gene is localized within intron 2.

Previously we have demonstrated the existence of stable transcripts from the noncoding strand of a rearranged c-myc gene in murine plasmacytomas in which the oncogene has translocated to an immunoglobulin constant-region gene element (M. Dean, R. B. Kent, and G. E. Sonenshein, Nature [London] 305:443-446, 1983). The resulting RNAs are chimeric, containing c-myc antisense and immunoglobulin sense sequences. A normal unrearranged murine c-myc gene is transcribed in the antisense orientation throughout much of the gene; however, stable transcripts have not been detected. In this study, using Northern (RNA) blot, S1 nuclease, and primer extension analyses, we have mapped the 5' end of the stable chimeric transcripts to a site 175 bp from the start of exon 3, within intron 2 of the c-myc gene. In vitro transcription assays with constructs containing this site and 400 bp upstream, in the antisense orientation, and nuclear extracts from plasmacytoma cells, as well as a number of cell lines with normal unrearranged c-myc genes, indicated that this promoter was functional. This finding was confirmed in transient transfection assays using the antisense promoter linked to the chloramphenicol acetyltransferase reporter gene. These results suggest that a normal promoter of antisense transcription is used following c-myc gene translocation.

Changes in mammographic densities induced by a hormonal contraceptive designed to reduce breast cancer risk.

BACKGROUND: It has been known for some time that oral contraceptives substantially reduce the risk of endometrial and ovarian cancer, but they do not reduce the risk of breast cancer. A hormonal contraceptive regimen has been developed which uses a gonadotropin-releasing hormone against (GnRHA) to suppress ovarian function, and this regimen includes the administration of very low doses of both estrogen and progestogen. This hormonal contraceptive regimen attempts to minimize exposure of the breast epithelium to these steroids and to preserve the maximum beneficial effects of estrogen, while still preventing endometrial hyperplasia. PURPOSE: Our purpose was to determine whether changes occurred in mammographic densities between baseline and 1 year for women on this hormonal contraceptive regimen with reduced estrogen and progestogen levels compared with women in a control group. METHODS: Twenty-one women were randomly assigned in a 2:1 ratio to the GnRHA-based contraceptive group (14 women) or to a control group (seven women). The contraceptive group received the following: 7.5 mg leuprolide acetate depot by intramuscular injection every 28 days; 0.625 mg conjugated estrogen by mouth for 6 days out of 7 every week; and 10 mg medroxyprogesterone acetate orally for 13 days every fourth 28-day cycle. The control group received no medication. Baseline and 1-year follow-up mammograms of contraceptive and control subjects were reviewed in a blinded fashion by two radiologists. RESULTS: Comparison of the changes between the baseline and 1-year mammograms in the two groups of women showed significant (P = .039) reduction in mammographic densities at 1 year for women on the contraceptive regimen. Assessing the reduction in mammographic densities by noting the fineness of fibrous septae showed a highly significant (P = .0048) difference in the contraceptive regimen group. One of the women on the contraceptive regimen was withdrawn from the study because of poor compliance. CONCLUSION: The reduced estrogen and progestogen exposures to the breast that were achieved by the hormonal contraceptive regimen resulted in substantial reductions in follow-up mammographic densities at 1 year compared with baseline. Although there is no direct evidence that such a reduction in densities will lead to a reduced risk of breast cancer, indirect evidence for a protective effect of this regimen is that early menopause reduces breast cancer risk, and that menopause is associated with a reduction in mammographic densities.

PIP: In California, physicians randomly assigned 21 women aged 25-40 to either the contraceptive group or the control group as part of a study aimed to determine whether or not a hormonal contraceptive regimen with reduced estrogen and progestogen levels affects mammographic densities. Eligibility criteria included premenopausal women with a 5-fold greater than normal risk of breast cancer, no prior cancer, bone mineral density not less than 2 standard deviations below normal, normal cholesterol, and a normal physical and pelvic examination. The contraceptive group received intramuscular injection of 7.5 mg leuprolide acetate depot every 28 days, 0.625 mg oral conjugated estrogen for 6 out of 7 days every week, and 10 mg oral medroxyprogesterone acetate for 13 days every fourth 28-day cycle. The reduction in mammographic densities in women on the contraceptive regimen between baseline and 1 year was significantly different than that of the controls whose mammographic densities remained essentially the same (p = 0.039). Cases had significantly more change in fibrous septae between baseline and 1 year than did controls (+0.82 units vs. -0.07; p = 0.0048). These results indicate that lower levels of estrogen and progestogen reduces mammographic densities, which may reduce the risk of breast cancer since increased mammographic densities are linked to an increased risk of breast cancer. Reduced mitotic activity in breast epithelial cells during menopause and with lower levels of estrogen and progestogen (i.e., reduced mammographic densities) suggest that early menopause may also protect against breast cancer.

Reevaluation of the maximum tolerated dose of continuous venous infusion of 5-fluorouracil with pharmacokinetics.

5-Fluorouracil (5-FU) was administered as a continuous ambulatory venous infusion to 25 patients in a Phase I trial. The principal dose limiting toxic effect observed was mucositis. Skin rash and diarrhea occurred less frequently. Hematological toxicity was modest, and no hepatic toxicity was seen. One partial remission of 138 days duration was seen in a patient with metastatic breast carcinoma who was previously refractory to a 5-FU combination regimen. Patient tolerance of 5-FU delivered in this manner appeared highly variable. On the basis of this trial, we recommend that future studies evaluating the efficacy of long-term venous infusion of 5-FU should utilize a dosage of 450 mg/m2/day.

Thymidylate synthetase inhibition in malignant tumors and normal liver of patients given intravenous 5-fluorouracil.

Single surgical biopsies of solid tumor were obtained at 20 to 240 min after drug administration in 21 patients given first-dose bolus i.v. 5-fluorouracil (5-FUra), 500 mg/sq m, and assayed for 5-fluorodeoxyuridylate (FdUMP), deoxyuridylate (dUMP), total thymidylate synthetase (TS), and non-FdUMP-bound, free enzyme. Nineteen patients had cancer of gastrointestinal origin, 13 of these colorectal, and 2 patients had breast adenocarcinoma. In 9 patients, synchronous biopsies of surgically normal liver were obtained along with samples of hepatic tumors metastatic from gastrointestinal sites. Total TS averaged 4.18 pmol/g in the malignant tissues and 2.23 pmol/g in liver. FdUMP levels in the gastrointestinal tumors were higher than in normal liver, were highest at the earliest time interval studied, 20 to 30 min, and appeared to decrease exponentially through 120 min. TS inhibition averaged 70 to 80% in gastrointestinal tumor biopsies and less than 50% in normal liver. Levels of dUMP were low and varied little with time. Those gastrointestinal tumors with higher FdUMP:dUMP ratios showed significantly greater TS inhibition. Tumors of 3 patients who benefited from 5-FUra therapy (1 patient with colonic adenocarcinoma and the 2 patients with breast adenocarcinoma) showed greater TS inhibition than did tumors of remaining patients. It is concluded that the apparent time course changes observed in FdUMP, dUMP, and TS in the grouped data are qualitatively similar to findings of murine studies in vivo and that the relationship between FdUMP:dUMP ratios and TS inhibition are consistent with established in vitro enzymic kinetics. Thus, biopsies of tumors at short time periods after 5-FUra administration may be usefully studied for biochemical parameters of TS inhibition, with the objectives of correlation of sensitivity to subsequent 5-FUra therapy and clarification of mechanisms of drug resistance.

White matter apoptosis is increased by delayed hypothermia and rewarming in a neonatal piglet model of hypoxic ischemic encephalopathy.

Therapeutic hypothermia is widely used to treat neonatal hypoxic ischemic (HI) brain injuries. However, potentially deleterious effects of delaying the induction of hypothermia and of rewarming on white matter injury remain unclear. We used a piglet model of HI to assess the effects of delayed hypothermia and rewarming on white matter apoptosis. Piglets underwent HI injury or sham surgery followed by normothermic or hypothermic recovery at 2h. Hypothermic groups were divided into those with no rewarming, slow rewarming at 0.5°C/h, or rapid rewarming at 4°C/h. Apoptotic cells in the subcortical white matter of the motor gyrus, corpus callosum, lateral olfactory tract, and internal capsule at 29h were identified morphologically and counted by hematoxylin & eosin staining. Cell death was verified by terminal deoxynucleotidyl transferase (TdT) dUTP nick end labeling (TUNEL) assay. White matter neurons were also counted, and apoptotic cells were immunophenotyped with the oligodendrocyte marker 2',3'-cyclic-nucleotide 3'-phosphodiesterase (CNPase). Hypothermia, slow rewarming, and rapid rewarming increased apoptosis in the subcortical white matter relative to normothermia (p<0.05). The number of white matter neurons was not lower in groups with more apoptosis after hypothermia or rapid rewarming, indicating that the apoptosis occurred among glial cells. Hypothermic piglets had more apoptosis in the lateral olfactory tract than those that were rewarmed (p<0.05). The promotion of apoptosis by hypothermia and rewarming in these regions was independent of HI. In the corpus callosum, HI piglets had more apoptosis than shams after normothermia, slow rewarming, and rapid rewarming (p<0.05). Many apoptotic cells were myelinating oligodendrocytes identified by CNPase positivity. Our results indicate that delaying the induction of hypothermia and rewarming are associated with white matter apoptosis in a piglet model of HI; in some regions these temperature effects are independent of HI. Vulnerable cells include myelinating oligodendrocytes. This study identifies a deleterious effect of therapeutic hypothermia in the developing brain.

Effects of IL-3 on promoter usage, attenuation and antisense transcription of the c-myc oncogene in the IL-3-dependent Ba/F3 early pre-B cell line.

The c-myc gene uses two major promoters, P1 and P2, for production of mRNA. In most proliferating normal cells, transcripts initiated from P2 predominate over the ones from P1. Furthermore, transcription of normal and translocated c-myc genes is bidirectional and overlapping. In this study, we have measured the effects of interleukin 3 (IL-3) deprivation and restimulation on c-myc promoter usage in the IL-3-dependent pre-B cell line Ba/F3. The rapid drop in c-myc mRNA expression observed in Ba/F3 cells upon IL-3 deprivation is reversible upon restimulation with interleukin. The use of P1 and P2 promoters, as judged by P1/P2 ratio, shifted from 0.2 in cells in exponential growth or in quiescence to 1.3 following IL-3 stimulation. This change was not due to selective instability of one of the two myc transcripts. In vitro nuclear run-on experiments indicated that IL-3 addition resulted in a large release of transcriptional attenuation, as well as a significant increase in transcriptional initiation. These results are consistent with the hypothesis that P1/P2 promoter usage is involved in the control of transcriptional elongation. Furthermore, deprivation of IL-3 resulted in a dramatic increase in antisense transcription, whereas little change was observed in the rate of initiation of elongation of c-myc mRNA precursors. This correlation suggests a negative role for antisense transcription in expression of c-myc mRNA levels in IL-3-deprived Ba/F3 cells.

A novel NF-kappa B element within exon 1 of the murine c-myc gene.

We have mapped a site within exon 1 of the murine c-myc gene that forms a variety of complexes with nuclear proteins derived from the murine WEHI 231 B-lymphoma cell line in exponential growth that are altered following treatment with phorbol ester, when transcription of this gene is reduced [Levine, R.A., McCormack, J.E., Buckler, A.J. & Sonenshein, G.E. (1986). Mol. Cell Biol., 6, 4112-4116]. This site, located at +440 to +459 bp relative to the P1 promoter, contains an NK-kappa B-like binding element. The sequence of this element, AGGGAATTTTT, is unusual in that the stretch of pyrimidines is entirely T residues. Binding of NF-kappa B protein was demonstrated by oligonucleotide competition, induction of binding upon 70Z/3 pre-B- to B-cell differentiation, response to GTP in the binding reaction, reduction of binding upon addition of I kappa B protein and uv cross-linking analysis. Functional activity of this internal regulatory element (IRE) was demonstrated in transfection assays using chloramphenicol acetyl transferase (CAT) reporter constructs containing multimerized copies of the IRE driving a heterologous promoter. Mutation of the IRE within the context of the c-myc promoter prevented NF-kappa B-mediated induction of transcription of this oncogene. Thus additional NF-kappa B elements may be defined by this new sequence.

Cardioprotection with dexrazoxane for doxorubicin-containing therapy in advanced breast cancer.

PURPOSE: To determine the cardioprotective effect of dexrazoxane (DZR) used in a doxorubicin-based combination therapy in advanced breast cancer. PATIENTS AND METHODS: Between November 1988 and January 1991, 534 patients with advanced breast cancer were randomized to two multicenter, double-blind studies (088001 and 088006). Patients received fluorouracil, doxorubicin, and cyclophosphamide (FAC) with either DZR (DZR-to-doxorubicin ratio, 10:1) or placebo (PLA) every 3 weeks and were monitored with serial multiplegated acquisition (MUGA) scans. RESULTS: The hazards ratio (HR) of PLA to DZR for a cardiac event, which was predefined ejection fraction changes or congestive heart failure (CHF), was 2.63 (95% confidence interval [CI], 1.61 to 4.27; P < .001) for 088001 and 2.00 (95% CI, 1.01 to 3.96; P = .038) for 088006. The objective response rates for 088001 were 46.8% for DZR and 60.5% for PLA, a difference of 14% (95% CI, -25% to -2%; P = .019), and for 088006 were 53.7% for DZR and 49.3% for PLA, a difference of 4% (95% CI, -13% to 22%; P = .63). Time to progression and survival were not significantly different between treatment arms in either study. Toxicities on the DZR arms included lower granulocyte and platelet counts at nadir (P = .009 and P = .004, respectively) and more pain on injection (P = .001), with no difference in the rates of fever, infection, or hemorrhage. CONCLUSION: DZR had a significant cardioprotective effect as measured by noninvasive testing and clinical CHF. One of the two studies (088001) showed a lower response rate with DZR, but time to progression and survival were not significantly different. DZR is the first agent shown to reduce cardiotoxicity from doxorubicin.

FGF and genes encoding transcription factors in early limb specification.

SnR, twist and Fgf10 are expressed in presumptive limb territories of early chick embryos. When FGF-2/FGF-8 beads are implanted in chick flank, an ectopic limb develops and SnR is irreversibly activated as early as 1 h. Ectopic Fgf10 and twist expression are activated much later at 17 and 20 h, respectively. FGF-10 can also induce SnR, but much later, and in this case activation occurs simultaneously with that of twist and Fgf10 via the Fgf8- expressing ridge. Tbx-4 and Tbx-5 are expressed in leg and wing forming regions, respectively, in a similar pattern to SnR and twist. FGF-2 leads to ectopic expression of Tbx-4 and Tbx-5 as rapidly as ectopic expression of SnR, but the patterns of ectopic transcripts suggest that induction of SnR and Tbx gene expression occur via different pathways.

Phase I and pharmacokinetic study of oral UFT, a combination of the 5-fluorouracil prodrug tegafur and uracil.

UFT is an oral preparation combining the 5-fluorouracil (FU) prodrug tegafur (FT) and uracil (U) in a 1:4 ratio, which is commercially available in Japan for the treatment of breast and gastrointestinal cancers. We sought to determine the tolerance of daily oral UFT and to relate this tolerance to the pharmacokinetics of FT and/or the derived FU, while exploring the possibility of circadian FU kinetics contributing to the results. A 28-day schedule followed by 2 weeks rest was began at the initial level of 300 mg/m2/day administered either at 8 a.m. or at 6 p.m. At the following level, 400 mg/m2/day patients were randomly assigned to a split-dose administration or to the above single, timed dose administration. Intolerance to single dosing was clearly demonstrated, and only the split dosing was advanced to 500 mg/m2/day. When this level proved too toxic, 400 mg/m2 was studied further on a 7 a.m., 3 p.m., and 11 p.m. (every 8 h) schedule. Pharmacology was determined on selected patients. In the single dose administration, areas under the curves of FU were higher following p.m. dosing, although substantial interpatient variation was present. Toxicities (diarrhea and neutropenia) were more severe in patients receiving the drug in single daily doses. We conclude that the kinetics of FT are saturable, with disproportionate increases in area under the curve (and toxicities) as dose levels are increased. With divided dosing, tolerance improves. UFT at a dose of 400 mg/m2/day administered as three divided doses (every 8 h) is suitable for Phase II studies, although toxicity requiring cessation of drug administration prior to completion of 28-day cycles will occur in some patients.

Pharmacokinetic and pharmacodynamic evaluation of the glycinamide ribonucleotide formyltransferase inhibitor AG2034.

Glycinamide ribonucleotide formyltransferase (GARFT) is a component of the de novo purine synthesis pathway. AG2034 is a specific inhibitor of GARFT that was designed based on the GARFT crystal structure. In conjunction with Phase I studies at four clinical centers in the United States and United Kingdom, AG2034 pharmacology was evaluated in 54 patients receiving 1-11 mg/m2 AG2034 as a 2-5 min injection. Blood samples were obtained just prior to and 5, 15, 30, and 45 min, and 1, 1.5, 2, 4, 6, 8, 12, 24, 48, 72, and 96 h after bolus injection during course 1. Limited sampling was also performed on course 3. Plasma AG2034 was measured using a sensitive and reproducible ELISA assay. AG2034 demonstrated a trimodal elimination pattern over 24 h, with median half-life (t(1/2))alpha = 8.7 min, t(1/2)beta = 72.6 min, and t(1/2)gamma = 364.2 min. AG2034 systemic clearance ranged from 9.4-144.5 ml/min/m2, and volume of distribution was 1.2-7.6 liters/m2. Course 1 AG2034 area under the concentration versus time curve (AUC) had a linear relationship with dose (r(s) = 0.86). Accumulation of AG2034 was evident, because course 3 AUC was higher than course 1 in 23 of 23 evaluable patients, but was not associated with an increase in erythrocyte AG2034. AG2034 systemic exposure had an impact on toxicity, because course 1 and course 3 AG2034 AUCs were significantly higher for patients with grade III/IV toxicity than patients with less than grade II toxicity (P < 0.001 and P = 0.001 for course 1 and course 3, respectively). This study demonstrates rapid systemic clearance of AG2034 and suggests pharmacokinetic approaches that may minimize patient toxicity and aid the development of this interesting class of anticancer agents.

Hormonal contraception and chemoprevention of female cancers.

Oral contraceptive (OC) use significantly reduces the risk of endometrial and ovarian cancer, has only a minimal effect on breast cancer, but may increase the risk of cervical cancer. These effects can be readily explained in terms of the effects of OCs on cell proliferation in these tissues. This analysis suggests how a hormonal contraceptive based on a GnRH agonist plus low-dose add-back sex steroids could be made that would greatly reduce lifetime risk of breast and ovarian cancer. Such a hormonal contraceptive is also likely to significantly reduce the lifetime risk of cervical cancer. It is also likely to reduce the risk of endometrial cancer, although not to the same extent as OCs.

Rat mesangial cells express two unique isoforms of laminin which modulate mesangial cell phenotype.

Rat mesangial cells express two unique isoforms of laminin which can be modulated by culture medium composition. To define further the nature of laminin expressed by cultured rat mesangial cells, synthesis of individual laminin chains, as well as their trimeric association, was examined. Based on data from Northern analysis of mRNA expression, immunoblots, immunofluorescence staining and radioimmunoprecipitation of biosynthetically labeled proteins, mesangial cells express laminin beta1, beta2, and gamma1 chains. Mesangial cells do not express laminin alpha1 or alpha2. MC produce a unique alpha chain, designated alpha'm. These laminin chains assemble into two major isoforms. One contains alpha'mbeta1gamma1, co-precipitates with entactin and is assembled into the fibrillar extracellular matrix. The second isoform contains alpha'mbeta2 and a presumed gamma chain that migrates in gel slightly ahead of gamma1. The beta2-containing isoform is concentrated in punctate sites on the cell surface. In addition, mesangial cells display different phenotypes when plated on laminin-1 (alpha1beta1gamma1), as compared to purified beta2. An LRE-containing peptide of laminin beta2 serves as an attachment site for mesangial cells and is sufficient to induce the phenotype observed with intact beta2. These data suggest that laminin isoform expression plays an important role in mesangial cell phenotype and function.

Sex steroids and breast cancer prevention.

Mitogenesis and mutagenesis are major driving forces in neoplastic development. Little is known about important breast mutagens, but much is known about breast mitogens. "Blocking" the effect of breast cell mitogens, by reducing the actual exposure of the breast to them, is an obvious strategy for breast cancer prevention. The ovarian hormones, estrogens and progesterone, are major effective (direct or indirect) breast cell mitogens. There is overwhelming epidemiologic evidence that breast cancer risk is closely related to exposure to estrogens and progestogens. A woman's exposure to endogenous ovarian estrogens and progesterone is drastically reduced by the use of combination-type oral contraceptives (COCs), but the exogenous synthetic estrogen and progestogen in the COC effectively replace the ovarian estrogen and progesterone, so that no decrease in breast cell exposure to these hormones is obtained. Doses of estrogen and progestogen in modern COCs are close to the minimum attainable, while still retaining both contraceptive efficacy and ovarian suppression (so that endogenous estrogen and progesterone do not add to the dose of estrogen and progestogen from the COC). Considerably lower effective breast cell exposure to estrogen and progestogen can, however, be achieved by using a gonadotropin-releasing hormone agonist to suppress ovarian function and compensating for the resulting hypoestrogenemia with low-dose hormone replacement. Such a contraceptive is predicted to reduce lifetime breast cancer risk by more than 50% if used for 10 years and by as much as 70% following 15 years of use. Contraception represents a unique opportunity to have a substantial beneficial impact on women's health; more than 10 million women use COCs daily in the United States.(ABSTRACT TRUNCATED AT 250 WORDS)