Targeting MYC-driven replication stress in medulloblastoma with AZD1775 and gemcitabine

Journal of Neuro-Oncology - MYC-driven medulloblastomas are highly aggressive childhood tumors with dismal outcomes and a lack of new treatment paradigms. We identified that targeting replication...     

Development of a synthetic peptide-based tartrate-resistant acid phosphatase radioimmunoassay for the measurement of bone resorption in rat serum

Selective markers of bone turnover provide a convenient and reproducible alternative to the complex and expensive histochemical techniques used commonly to study the effect of pharmacological agents and the pathogenesis of bone disease in the ovariectomized (OVX) rat model. One marker, which has been specifically linked to terminally differentiated osteoclasts and, thus, provides useful insight at cellular levels, is type-5 tartrate-resistant acid phosphatase (TRACP). We describe the development of a TRACP radioimmunoassay (RIA), which requires synthetic peptide for antibody development. To develop the RIA, polyclonal antibodies were generated in goats against a synthetic peptide, DPSVRHQRKCY, corresponding to amino acid residues 267–275 of the rat type-5 TRACP sequence. In the RIA, 50 μl of rat serum, 100 μl of goat anti-TRACP antibodies, and 100 μl of tracer were incubated overnight. The antibody-bound fraction was separated, counted, and unknown values were calculated by comparison with the peptide calibrator. Rat serum shows parallelism with the synthetic peptide calibrator used in the RIA. The sensitivity of the RIA was 24.7 μg/l, and the measuring range was 19–2476 μg/l. The average intra-assay coefficients of variation for (CV) two controls were less than 7%. The average dilution and spike recoveries were 107% and 87%, respectively. We applied our peptide-based RIA to study bone resorption in an OVX rat model. TRACP concentrations in serum in 12-week-old OVX Sprague Dawley rats were 14%–22% (P < 0.05) higher than those in the sham-operated rats, and TRACP concentrations in OVX rats treated with estradiol were 24%–32% lower (P < 0.01) than those in the vehicle-treated OVX group. Similarly, as compared with those in OVX rats, TRACP concentrations decreased to those of sham levels in OVX rats receiving 10 μg/kg per day of alendronate for 10 days. In addition, the TRACP levels determined by RIA showed a significant correlation with serum C-telopeptide (type-I collagen) concentrations (r = 0.56; P < 0.001) measured by an enzyme-linked immunosorbent assay (ELISA) developed earlier for the rat model. In conclusion, we have developed a TRACP RIA that could be used to monitor the rate of bone resorption in the rat model. Received: June 18, 2001 / Accepted: October 26, 2001     

A time course of bone response to jump exercise in C57BL/6J mice

 Exercise, by way of mechanical loading, provides a physiological stimulus to which bone tissue adapts by increased bone formation. The mechanical stimulus due to physical activity depends on both the magnitude and the duration of the exercise. Earlier studies have demonstrated that jump training for 4 weeks produces a significant bone formation response in C57BL/6J mice. An early time point with significant increase in bone formation response would be helpful in: (1) designing genetic quantitative trait loci (QTL) studies to investigate genes regulating the bone adaptive response to mechanical stimulus; and (2) mechanistic studies to investigate early stimulus to bone tissue. Consequently, we investigated the bone structural response after 2, 3, and 4 weeks of exercise with a loading cycle of ten jumps a day. We used biochemical markers and peripheral quantitative computed tomography (pQCT) of excised femur to measure bone density, bone mineral content (BMC), and area. Four-week-old mice were separated into control (n= 6) and jump groups (n= 6), and the latter groups of mice were subjected to jump exercise of 2-week, 3-week, and 4-week duration. Data (pQCT) from a mid-diaphyseal slice were used to compare bone formation parameters between exercise and control groups, and between different time points. There was no statistically significant change in bone response after 2 weeks of jump exercise as compared with the age-matched controls. After 3 weeks of jump exercise, the periosteal circumference, which is the most efficient means of measuring adaptation to exercise, was increased by 3% (P < 0.05), and total and cortical area were increased by 6% (P < 0.05) and 11% (P < 0.01), respectively. Total bone mineral density (BMD) increased by 11% (P < 0.01). The biggest changes were observed in cortical and total BMC, with the increase in total BMC being 12% (P < 0.01). Interestingly, the increase in BMC was observed throughout the length of the femur and was not confined to the mid-diaphysis. Consistent with earlier studies, mid-femur bone mass and area remained significantly elevated in the 4-week exercise group when compared with the control group of mice. The levels of the biochemical markers osteocalcin, skeletal alkaline phosphatase, and C-telopeptide were not significantly different between the exercise and control groups, indicating the absence of any systemic response due to the exercise. We conclude that a shorter exercise regimen, of 3 weeks, induced a bone response that was greater than or equal to that of 4 weeks of jump exercise reported earlier. Received: October 1, 2001 / Accepted: January 18, 2002     

Leiomyosarcoma of the inferior vena cava: a case report and review of literature

Tumors of the inferior vena cava are rare, and most of these are leiomyosarcomas. They are most frequent in the sixth decade of life, with a female predominance. We present a 45-year-old male patient with a tumor involving the entire extent of the inferior vena cava. Computerized tomography revealed a heterogeneously enhancing mass with marked expansion of the inferior vena cava with extraluminal extension. Computerized tomography--guided biopsy of the extraluminal component showed features of a fasciculated spindle cell tumor positive for vimentin, smooth muscle actin, and calponin and negative for S-100 antigen. We discuss the clinical presentation imaging findings and review the literature.     

Diagnostic assessment of laryngeal cancer

Laryngeal carcinoma must be diagnosed expeditiously to maximize curative efforts. Our approach combines useful aspects of the patient's presentation with application of appropriate diagnostic modalities. Newer methods of assessment and follow-up are being scientifically validated and will likely enhance the diagnostic efforts of the head and neck surgical oncologist.     

Analytical and clinical evaluation of the Bio-Rad HPLC kit for measurement of type I collagen cross links

 The measurement of hydroxylysylpyridinoline (PYD) and lysylpyridinoline (DPD), the degradation products of type I collagen, by manual HPLC assay posed practical difficulties. The present study was undertaken to evaluate the first commercially available HPLC kit, which provides a convenient substitute for cumbersome classical HPLC methods. The HPLC procedure is based on an improved sample clean-up chromatography, convenient ready-to-use HPLC reagents, and quicker isocratic elution of PYR and DPD on reverse-phase analytical column. The analytical parameters assessed include sensitivity, within- and between-assay variation, method comparison, recoveries, and interference. Clinical evaluation included discriminatory power of PYD and DPD and response to treatment of osteoporosis patients with Alendronate. DPD and PYD concentrations showed linear (r ² > 0.99) response between 10–400 pmol/ml and 75–4000 pmol/ml, respectively. The average within-assay imprecision, over a range of clinically relevant cross-links concentrations, was CV < 7% (n = 30). The total imprecision (n = 35 days), by ANOVA, for PYD and DPD was CV < 7.5% and CV < 10%, respectively. Average spike recovery was 95.4% ± 6.5%. Comparison with the historical HPLC method exhibited a close correlation (r values between 0.87 and 0.91, P < 0.0001). Creatinine-corrected DPD in postmenopausal (Z score = 2.4, P < 0.05, n = 17) and osteoporotic (Z score = 3.0, P < 0.01, n = 29) women were 44% and 64% higher, respectively, compared to premenopausal samples (n = 15). Similarly, PYD concentration was 26% and 54% higher in postmenopausal and postmenopausal osteoporotic women, respectively. There was a 47% (P < 0.001) decrease in DPD concentration (n = 16), and a 30% decrease in PYD concentration after 90 days of treatment of osteoporotic patients with Alendronate. DPD concentration correlated with N-telopeptide with an r value of 0.69 (n = 67, P < 0.0001). The reported kit method is substantially simpler and precise than the manual method. DPD concentrations determined by the current method reaffirm the clinical value in identifying increased bone resorption in pathological conditions and monitoring response to antiresorptive therapy. Received: June 28, 2002 / Accepted: November 6, 2002 Offprint requests to: D.J. Baylink     

Pharmacogenomics: road to anticancer therapeutics nirvana?

Interindividual differences in the toxicity and response to anticancer therapies are currently observed for essentially all available treatment regimens. Such 'unpredictable' drug responses are particularly dangerous in the context of anticancer agents that have narrow therapeutic indices. Pharmacogenomics attempts to elucidate the inherited basis of interindividual differences in drug response, with the eventual goal of minimizing such variability through the use of 'individualized' treatments. There are several emerging examples of genetic polymorphisms of drug-metabolizing enzymes, DNA repair genes and drug targets that have been shown to influence the toxicity and efficacy of anticancer treatment. This review discusses the role of genetic variants of UGT1A1, TS and EGFR to exemplify the potential impact of phramacogenomics on the field of anticancer therapeutics.     

Attitudes and perceptions regarding subspecialty training in female pelvic medicine and reconstructive surgery

The objective of the study was to evaluate perceptions regarding subspecialty training in female pelvic medicine and reconstructive surgery (FPMRS) in the United States. A 57-item questionnaire was anonymously mailed to fellows and applicants to FPMRS fellowship. Seventy-four American fellowship interviewees and current fellows completed the entire questionnaire (56% response rate). Key factors associated with higher interest in FPMRS compared to general obstetrics and gynecology (OBG) included competitiveness to get into fellowship and new developments. Key factors associated with higher interest in FPMRS compared to other subspecialties in obstetrics and gynecology (SUB) were lower risk of malpractice and higher sense of career satisfaction. Commonly cited attributes of FPMRS that attract to the field relate to the complexity of cases and the quantity of time spent in the operating room. Majority of responders preferred academics over private practice or a mixture (55.4%, 17.6%, and 27%, respectively). The most important reason for interest in FPMRS compared to OBG and SUB is quality time in the operating room and lower risk of malpractice, respectively. Results of this study may help attract medical students to OBG and help mentors with career counseling.