Citations

AbstractIron-regulatory proteins (IRPs) 1 and 2 posttranscriptionally regulate expression of transferrin receptor (TfR), ferritin, and other iron metabolism proteins. Mice with targeted deletion of IRP2 overexpress ferritin and express abnormally low TfR levels in multiple tissues. Despite this misregulation, there are no apparent pathologic consequences in tissues such as the liver and kidney. However, in the central nervous system, evidence of abnormal iron metabolism in IRP2-/- mice precedes the development of adult-onset progressive neurodegeneration, characterized by widespread axonal degeneration and neuronal loss. Here, we report that ablation of IRP2 results in iron-limited erythropoiesis. TfR expression in erythroid precursors of IRP2-/- mice is reduced, and bone marrow iron stores are absent, even though transferrin saturation levels are normal. Marked overexpression of 5-aminolevulinic acid synthase 2 (Alas2) results from loss of IRP-dependent translational repression, and markedly increased levels of free protoporphyrin IX and zinc protoporphyrin are generated in IRP2-/- erythroid cells. IRP2-/- mice represent a new paradigm of genetic microcytic anemia. We postulate that IRP2 mutations or deletions may be a cause of refractory microcytic anemia and bone marrow iron depletion in patients with normal transferrin saturations, elevated serum ferritins, elevated red cell protoporphyrin IX levels, and adult-onset neurodegeneration.

AbstractCyclin-dependent kinase (CDK) inhibitors have the potential to induce cell-cycle arrest and apoptosis in cancer cells. Seliciclib (CYC202 or R-roscovitine) is a potent CDK inhibitor currently undergoing phase-2 clinical testing in lung and B-cell malignancies. Here we studied the in vitro cytotoxic activity of seliciclib against multiple myeloma (MM) cells. Our data demonstrate that seliciclib has potent cytotoxicity against MM cells that are both sensitive and resistant to conventional therapy as well as primary MM cells from patients. Cell-cycle and Western blot analysis confirmed apoptosis. Importantly, seliciclib triggered a rapid down-regulation of Mcl-1 transcription and protein expression independent of caspase cleavage. Adherence of MM cells to bone marrow stromal cells (BMSCs) induced increased Mcl-1 expression associated with signal transducer and activator of transcription 3 (STAT3) phosphorylation, which was inhibited in a time- and dose-dependent manner by seliciclib. Furthermore, seliciclib inhibited interleukin 6 (IL-6) transcription and secretion triggered by tumor cell binding to BMSCs. Up-regulation of Mcl-1 expression in cocultures was only partially blocked by neutralizing antibody to IL-6, suggesting alternative mechanisms of Mcl-1 modulation by seliciclib. Finally, combination studies of seliciclib with doxorubicin and bortezomib show in vitro synergism, providing the rationale for testing these drug combinations to improve patient outcome in MM.

Extracellular proteolysis plays a key role in many pathophysiologic processes including cancer, inflammatory diseases, and cardiovascular conditions such as atherosclerosis and restenosis. Whereas matrix metalloproteinases are their best known member, many others are becoming better known. The extracellular proteases are a complex and heterogeneous superfamily of enzymes. They include metalloproteinases (matrix metalloproteinases, adamalysins, or pappalysins), serine proteases (elastase, coagulation factors, plasmin, tissue plasminogen activator, urokinase plasminogen activator), and the cysteine proteases (such cathepsins). In addition to their matrix degradation capabilities, they have other less well known biologic functions that include angiogenesis, growth factor bioavailability, cytokine modulation, receptor shedding, enhancing cell migration, proliferation, invasion, and apoptosis. This review discusses extracellular proteases relevant to the vasculature, their classification and function, and how protease disorders contribute to arterial plaque growth, including chronic atherosclerosis, acute coronary syndromes, restenosis, and vascular remodeling. These broad extracellular protease functions make them potentially interesting therapeutic targets.

The mechanisms mediating the more striking age related increase in cardiovascular disease in women than in men are poorly understood. We tested the hypothesis that aging has a greater impact on sympathetic traffic in women than in men. Muscle sympathetic nerve activity (MSNA), blood pressure, and heart rate were measured in 120 healthy males and 96 healthy females aged 20 to 72 years. MSNA increased with age in both sexes, but age explained 53% of MSNA variance in female subjects and only 8% of MSNA variance in male subjects. Both the slope and intercept of the regression lines were significantly different between male and female groups ( P <0.01 and P <0.001, respectively). For each decade of life, women showed an increase of 6.5 bursts/min in comparison to an increase of 2.6 bursts/min in males. Menopause did not explain the age-related increase in sympathetic traffic. For every 10-burst/min increment in MSNA in subjects older than 40, mean blood pressure increased by 2.7 mm Hg in men and by 6.1 mm Hg in women. Aging is accompanied by a greater increase in sympathetic traffic in women than in men, independent of menopausal status. Sympathetic neural mechanisms may contribute importantly to the more marked influence of age on blood pressure and cardiovascular disease in women.

The prenatally androgenised female rhesus monkey has become a model for polycystic ovary syndrome (PCOS) in women, with early prenatal androgenisation entraining a permanent PCOS-like phenotype characterised by luteinising hormone (LH) hypersecretion due to reduced hypothalamic sensitivity to steroid negative feedback and relative insulin excess associated with increased abdominal adiposity. These combined reproductive and metabolic abnormalities occur in combination with ovarian hyperandrogenism and follicular arrest in adulthood, and with premature follicle differentiation and impaired embryo development during gonadotrophin therapy for in vitro fertilization (IVF). The ability of prenatal androgen excess in fetal rhesus monkeys to entrain multiple organ systems in utero provides evidence that the hormonal environment of intrauterine life programmes target tissue differentiation, raising the possibility that hyperandrogenism in human fetal development promotes PCOS in adulthood. This hypothesis developed in prenatally androgenised female rhesus monkeys, however, also must include data from clinical studies of PCOS to clarify the homology between human and non-human primates in intrafollicular steroidogenesis and its impact on oocyte developmental competency. By doing so, future studies promise to develop new clinical strategies that will lead to improved pregnancy outcome and reduced pregnancy loss in women with disorders of insulin action, including PCOS, obesity and diabetes mellitus.

Abstract Background. Small bowel adenocarcinoma is a rare gastrointestinal malignancy that is treated primarily with surgery. Even with optimal resection, however, survival is poor and recurrences are common. Response rates to palliative combination chemotherapy are low, and the median duration of survival for metastatic disease is less than 1 year. This study aimed to document the response rate and survival time for patients with advanced small bowel adenocarcinoma who were not surgically curable and were treated with a regimen of 5-fluorouracil (5-FU), mitomycin C (Mutamycin®; Bristol-Myers Squibb; Princeton, NJ), and doxorubicin (Adriamycin®; Bedford Laboratories; Bedford, OH), the FAM regimen. Methods. This multi-institutional study was performed by the Eastern Cooperative Oncology Group (ECOG). Between November, 1983 and December, 1985, 39 patients with advanced or recurrent disease were enrolled. Chemotherapy was given as follows: 5-FU, 600 mg/m2 on days 1, 8, 29 and 36; mitomycin C, 10 mg/m2 on day 1; and doxorubicin, 30 mg/m2 on days 1 and 29. Eligibility criteria included an ECOG performance status score of 0–2, measurable disease, and adequate baseline organ function. Prior chemotherapy was allowed. Response was measured by examination and imaging techniques. Survival time and time to progression were evaluated by the method of Kaplan and Meier, and these outcomes were stratified by clinical and laboratory covariates. Results. Of the 39 evaluated patients, 38 were eligible and 36 were evaluable for response. Grade 3–5 toxicities were experienced by a total of 26 patients (20 grade 3, 5 grade 4, 1 grade 5). The most common adverse events were neutropenia and vomiting. Responses were seen in a total of seven patients (2 complete responses, 5 partial responses), for a response rate of 18.4% (95% confidence interval of 7.8%–34.4%). The median survival time was 8 months. Conclusions. The FAM regimen was active and tolerable for patients with advanced small bowel adenocarcinoma; however, the results were no better than those seen with other chemotherapy combinations.

Background— Although segmental or circumferential ablation is effective in eliminating pulmonary vein (PV)–mediated atrial fibrillation (AF), this procedure may be complicated by the occurrence of PV stenosis. Methods and Results— To establish the clinical presentation, diagnostic manifestations, and interventional management of PV stenosis, 23 patients with stenosis of 34 veins complicating ablation of AF were evaluated. Each patient became symptomatic 103±100 days after undergoing ablation. In 8 veins, the ablation producing the PV stenosis was a repeated procedure for continued AF. Nineteen patients presented with dyspnea on exertion, 7 with dyspnea at rest, 9 with cough, and 6 with chest pain. On multirow spiral computed tomography examination, the narrowest lumen of the affected PVs measured 3±2 mm compared with 13±3 mm at baseline ( P ≤0.001). The relative perfusion of affected lung segments on isotope scans was reduced to 4±3% of total perfusion compared with 22±10% in unaffected segments. At percutaneous intervention, these veins showed 80±13% stenosis, with a mean gradient of 12±5 mm Hg. This was significantly reduced to a residual stenosis of 9±8% ( P ≤0.001) and a residual gradient of 3±4 mm Hg ( P ≤0.001). Twenty veins were treated with balloon dilatation alone, whereas 14 veins were stented with standard 10-mm-diameter bare-metal stents. Although the symptomatic response was nearly immediate and impressive, 14 patients developed in-stent or in-segment restenosis, requiring repeated interventions in 13. Conclusions— Percutaneous intervention produces rapid and dramatic symptom relief in patients with highly symptomatic PV stenosis after radiofrequency ablation for AF. Nevertheless, alternative treatment methods will be required to decrease recurrent in-stent or in-segment restenosis.