Structure-based design of highly selective 2,4,5-trisubstituted pyrimidine CDK9 inhibitors as anti-cancer agents

Cyclin-dependent kinases (CDKs) are a family of Ser/Thr kinases involved in cell cycle and transcriptional regulation. CDK9 regulates transcriptional elongation and this unique property has made it a potential target for several diseases. Due to the conserved ATP binding site, designing selective CDK9 inhibitors has been challenging. Here we report our continued efforts in the optimization of 2,4,5-tri-substituted pyrimidine compounds as potent and selective CDK9 inhibitors. The most selective compound 30m was >100-fold selective for CDK9 over CDK1 and CDK2. These compounds showed broad anti-proliferative activities in various solid tumour cell lines and patient-derived chronic lymphocytic leukaemia (CLL) cells. Decreased phosphorylation of the carboxyl terminal domain (CTD) of RNAPII at Ser-2 and down-regulation of anti-apoptotic protein Mcl-1 were confirmed in both the ovarian cancer model A2780 and patient-derived CLL cells.

Influence of common clinical variables on intraoperative parathyroid hormone monitoring during surgery for primary hyperparathyroidism

BACKGROUND

Intraoperative monitoring of parathyroid hormone (IOPTH) is a reliable method of predicting the cure of primary hyperparathyroidism (PHPT). The aim of this study is to assess whether common clinical variables (CCV) frequently encountered in patients with PHPT may affect the magnitude of PTH drop or the likelihood of patients meeting the intraoperative cure criterion.

DESIGN

Patients who were surgically cured from PHPT caused by single gland disease (SGD) and had full IOPTH protocol (4 measurements) were stratified according to age, gland weight, renal function, vitamin D status and severity of hypercalcemia. The percentage of IOPTH drop and the frequency of patients who had true positive IOPTH test results were compared among groups.

RESULTS

762 patients had surgery for PHPT, of whom 746 were (98%) cured. Of these 746 patients, 511 who had SGD and a full IOPTH protocol were included in this study. The median IOPTH drop was significantly higher among younger patients, those with severe hypercalcaemia at 5, 10, 15 min after gland excision, giant glands (at 5-min only), patients with vitamin D deficiency (at 10, 15 min), and those with normal renal function (at 15 min only). The likelihood of the patients meeting the intraoperative cure criterion was not significantly affected among the groups except in patients with mild hypercalcaemia, who were significantly less likely to have 50% IOPTH drop than those with severe hypercalcaemia at all time points. The frequency of mildly hypercalcaemic patients who met cure criterion was significantly improved by extending measurement to 15 min.

CONCLUSIONS

IOPTH monitoring has the ability to mitigate the variability of IOPTH kinetics associated with most clinical variables. Mildly hypercalcemic patients in particular may benefit from waiting for 15-min measurement before any surgical decision is made.

Targeting CDK9 for treatment of colorectal cancer

Colorectal cancer (CRC) remains one of the most lethal human malignancies, and pursuit of new therapeutic targets for treatment has been a major research focus. Cyclin-dependent kinase 9 (CDK9), which plays a crucial role in transcription, has emerged as a target for cancer treatment. CDKI-73, one of the most potent and pharmacologically superior CDK9 inhibitors, has demonstrated excellent anti-tumour efficacy against several types of cancers. In this study, we evaluated its therapeutic potential against CRC. CDKI-73 elicited high cytotoxicity against all colon cancer cell lines tested. Cell cycle and apoptosis analysis in HCT 116 and HT29 cells revealed that CDKI-73 induced cell death without accumulation of DNA at any phase of the cell cycle. Moreover, it caused depolarisation of mitochondrial membrane, leading to caspase-independent apoptosis. Knockdown by shRNA demonstrated the CDK9-targeted mechanism of CDKI-73, which also affected the Mnk/eIF4E signalling axis. In addition, RT-qPCR analysis showed that CDKI-73 down-regulated multiple pro-survival factors at the mRNA level. Its in vivo anti-tumour efficacy was further evaluated in Balb/c nude mice bearing HCT 116 xenograft tumours. CDKI-73 significantly inhibited tumour growth (***P < 0.001) without overt toxicity. Analysis of the tumour tissues collected from the xenografted animals confirmed that the in vivo anti-tumour efficacy was associated with CDK9 targeting of CDKI-73. Overall, this study provides compelling evidence that CDKI-73 is a promising drug candidate for treating colorectal cancer.

The evolution of methods for urinary steroid metabolomics in clinical investigations particularly in childhood

The metabolites of cortisol, and the intermediates in the pathways from cholesterol to cortisol and the adrenal sex steroids can be analysed in a single separation of steroids by gas chromatography (GC) coupled to MS to give a urinary steroid profile (USP). Steroids individually and in profile are now commonly measured in plasma by liquid chromatography (LC) coupled with MS/MS. The steroid conjugates in urine can be determined after hydrolysis and derivative formation and for the first time without hydrolysis using GC-MS, GC-MS/MS and liquid chromatography with mass spectrometry (LC-MS/MS). The evolution of the technology, practicalities and clinical applications are examined in this review. The patterns and quantities of steroids changes through childhood. Information can be obtained on production rates, from which children with steroid excess and deficiency states can be recognised when presenting with obesity, adrenarche, adrenal suppression, hypertension, adrenal tumours, intersex condition and early puberty, as examples. Genetic defects in steroid production and action can be detected by abnormalities from the GC-MS of steroids in urine. New mechanisms of steroid synthesis and metabolism have been recognised through steroid profiling. GC with tandem mass spectrometry (GC-MS/MS) has been used for the tentative identification of unknown steroids in urine from newborn infants with congenital adrenal hyperplasia. Suggestions are made as to areas for future research and for future applications of steroid profiling. As routine hospital laboratories become more familiar with the problems of chromatographic and MS analysis they can consider steroid profiling in their test repertoire although with LC-MS/MS of urinary steroids this is unlikely to become a routine test because of the availability, cost and purity of the internal standards and the complexity of data interpretation. Steroid profiling with quantitative analysis by mass spectrometry (MS) after chromatography now provides the most versatile of tests of adrenal function in childhood.

Discovery and pharmacological characterization of a novel series of highly selective inhibitors of cyclin-dependent kinases 4 and 6 as anticancer agents

BACKGROUND AND PURPOSE

Cyclin D-dependent kinases 4 and 6 (CDK4/6) are crucial regulators of the G1 to S phase transition of the cell cycle and are actively pursued as therapeutic targets in cancer. We sought to discover a novel series of orally bioavailable and highly selective small molecule inhibitors of CDK4/6.

EXPERIMENTAL APPROACH

The discovery of pharmacological inhibitors and optimization for potency, selectivity and drug properties were achieved by iterative chemical synthesis, biochemical screening against a panel of kinases, cell-based assays measuring cellular viability, cell cycle distribution, induction of apoptosis and the level of retinoblastoma tumour suppressor protein (Rb) phosphorylation and E2 factor (E2F)-regulated gene expression and in vitro biopharmaceutical and in vivo pharmacokinetic profiling.

KEY RESULTS

We discovered several lead compounds that displayed >1000-fold selectivity for CDK4/6 over other members of the CDK family. The lead compounds, 82, 91 and 95, potently inhibited the growth of cancer cells by inducing G1 arrest with a concomitant reduction in the phosphorylation of Rb at S780 and in E2F-regulated gene expression. With a remarkable selectivity for CDK4 over 369 human protein kinases, 91 was identified as a highly potent and orally bioavailable drug candidate.

CONCLUSIONS AND IMPLICATIONS

We have identified unique and new inhibitors of CDK4/6 as potential drug candidates. Compound 91 represents an ideal candidate for further development as targeted cancer therapy.

Anesthesia for patients with tracheal bronchus

Tracheal bronchus is a congenital anatomical variant of patients with accessory bronchus in the right upper lobe deriving directly from the supracarinal trachea. Pre-operative consultation with the anesthesiologist is important for patient safety and can avoid adverse effects induced by endotracheal intubation. In this report, we described a case of tracheal bronchus in which general anesthesia was performed for video-assisted thoracoscopic surgery. We discussed some of the issues surrounding to complications in tracheal bronchus.

Abstract 2353: CDKI-15, a novel and highly selective CDK4/6 inhibitor: discovery, in vitro and in vivo anticancer efficacy

Cyclin D dependent kinases CDK4 & CDK6 are crucial regulators of the G1 to S phase transition of the cell cycle. The facts that myriad cancer types show aberrance in INK4-CDK4/6-cyclin D-Rb-E2F pathway, & the rapidly emerging positive clinical data of pharmacological inhibitors have validated CDK4/6 as anticancer drug targets. As the first commercialized CDK inhibitor, palbociclib in combination with letrozole or fulvestrant has received regulatory approval for the treatment of breast cancer. This represents an important scientific advance in the field. However, the limited structural diversity & undesired side effects due to broader kinase interactions of existing inhibitors mean that the hunt for new & highly selective CDK4/6 inhibitor drug candidates continues. Using our advanced medicinal chemistry, targeted biochemical & cell-based assays, & animal pharmacology, we synthesized & evaluated a novel series of inhibitors. Many compounds were highly potent & selective against CDK4/6, & exhibited low nanomolar potency against a range of human cancer cell lines. Notably, inhibition of CDK4D1 by compound CDKI-15 (Ki = 4 nM) was over 3 orders of magnitude greater than CDK1B, CDK2A, CDK7H & CDK9T1. Interrogation of a panel of 369 protein kinases revealed CDKI-15 to be highly selective for CDK4/6 with only 3 other kinases inhibited potently. CDKI-15 reduced the level of Rb phosphorylation & induced G1 cell cycle arrest, confirming cellular inhibition of CDK4/6 in cancer cells. Moreover, CDKI-15 possesses superior pharmacokinetic profile with oral bioavailability of 100% in mice. Treatment of nude BALB/c mice bearing human MV4-11 acute myeloid leukemia cells with CDKI-15 at daily dose of 100 mg/kg by oral administration resulted in a robust inhibition of tumor growth compared to vehicle treated animals (T/C = 30%, p &lt; 0.00001). Strikingly, CDKI-15 caused a complete & sustained tumor regression in one-third of the animals. No detectable toxicity was observed in the animals during & post treatment. Taken together, our data provide a rationale for CDKI-15 to be developed towards clinic for cancer therapy.

Citation Format: Solomon Tadesse, Laychiluh Bantie, Khamis Tomusange, Saiful Islam, Muhammed H. Rahaman, Benjamin Noll, Frankie Lam, Mingfeng Yu, Shudong Wang. CDKI-15, a novel and highly selective CDK4/6 inhibitor: discovery, in vitro and in vivo anticancer efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2353. doi:10.1158/1538-7445.AM2017-2353

Highly Potent, Selective, and Orally Bioavailable 4-Thiazol-N-(pyridin-2-yl)pyrimidin-2-amine Cyclin-Dependent Kinases 4 and 6 Inhibitors as Anticancer Drug Candidates: Design, Synthesis, and Evaluation

Cyclin D dependent kinases (CDK4 and CDK6) regulate entry into S phase of the cell cycle and are validated targets for anticancer drug discovery. Herein we detail the discovery of a novel series of 4-thiazol-N-(pyridin-2-yl)pyrimidin-2-amine derivatives as highly potent and selective inhibitors of CDK4 and CDK6. Medicinal chemistry optimization resulted in 83, an orally bioavailable inhibitor molecule with remarkable selectivity. Repeated oral administration of 83 caused marked inhibition of tumor growth in MV4-11 acute myeloid leukemia mouse xenografts without having a negative effect on body weight and showing any sign of clinical toxicity. The data merit 83 as a clinical development candidate.

Targeting RNA transcription and translation in ovarian cancer cells with pharmacological inhibitor CDKI-73

Dysregulation of cellular transcription and translation is a fundamental hallmark of cancer. As CDK9 and Mnks play pivotal roles in the regulation of RNA transcription and protein synthesis, respectively, they are important targets for drug development. We herein report the cellular mechanism of a novel CDK9 inhibitor CDKI-73 in an ovarian cancer cell line (A2780). We also used shRNA-mediated CDK9 knockdown to investigate the importance of CDK9 in the maintenance of A2780 cells. This study revealed that CDKI-73 rapidly inhibited cellular CDK9 kinase activity and down-regulated the RNAPII phosphorylation. This subsequently caused a decrease in the eIF4E phosphorylation by blocking Mnk1 kinase activity. Consistently, CDK9 shRNA was also found to down-regulate the Mnk1 expression. Both CDKI-73 and CDK9 shRNA decreased anti-apoptotic proteins Mcl-1 and Bcl-2 and induced apoptosis. The study confirmed that CDK9 is required for cell survival and that ovarian cancer may be susceptible to CDK9 inhibition strategy. The data also implied a role of CDK9 in eIF4E-mediated translational control, suggesting that CDK9 may have important implication in the Mnk-eIF4E axis, the key determinants of PI3K/Akt/mTOR- and Ras/Raf/MAPK-mediated tumorigenic activity. As such, CDK9 inhibitor drug candidate CDKI-73 should have a major impact on these pathways in human cancers.

Enhanced 3-epi-25-hydroxyvitamin D3 signal leads to overestimation of its concentration and amplifies interference in 25-hydroxyvitamin D LC-MS/MS assays

Background

3-epi-25-hydroxyvitamin D3 (3-epi-25OHD3) interferes in most liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays for 25-hydroxyvitamin D (25OHD). The clinical significance of this is unclear, with concentrations from undetectable to 230 nmol/L reported. Many studies have quantified 3-epi-25OHD3 based on 25OHD3 calibrators or other indirect methods, and we speculated that this contributes to the observed variability in reported 3-epi-25OHD3 concentrations.

Methods

We compared continuous MS/MS infusions of 3-epi-25OHD3 and 25OHD3 solutions, spiked both analytes into the same serum matrix and analysed patient samples to assess the effect of three different quantitation methods on 3-epi-25OHD3 concentration. Experiments were performed on an LC-MS/MS system using a phenyl column which does not resolve 3-epi-25OHD3, and a modified method utilizing a Zorbax SB-CN column that chromatographically resolves 3-epi-25OHD3 from 25OHD3.

Results

A greater 3-epi-25OHD3 signal, compared with 25OHD3, was observed during equimolar post-column continuous infusion of analyte solutions, and following analysis of a serum pool spiked with both analytes. 3-epi-25OHD3 signal enhancement was dependent on mobile phase composition. Compared with 3-epi-25OHD3 calibrators, indirect quantitation methods resulted in up to 10 times as many samples having 3-epi-25OHD3 concentrations ≥ 10 nmol/L, and an approximately fourfold increase in the maximum observed 3-epi-25OHD3 concentration to 95 nmol/L.

Conclusions

Enhanced 3-epi-25OHD3 signal leads to overestimation of its concentrations in the indirect quantitation methods used in many previous studies. The enhanced signal may contribute to greater interference in some 25OHD LC-MS/MS assays than others. We highlight that equimolar responses cannot be assumed in LC-MS/MS systems, even if two molecules are structurally similar.

Substituted 4-(thiazol-5-yl)-2-(phenylamino)pyrimidines are highly active CDK9 inhibitors: synthesis, X-ray crystal structures, structure-activity relationship, and anticancer activities

Cancer cells often have a high demand for antiapoptotic proteins in order to resist programmed cell death. CDK9 inhibition selectively targets survival proteins and reinstates apoptosis in cancer cells. We designed a series of 4-thiazol-2-anilinopyrimidine derivatives with functional groups attached to the C5-position of the pyrimidine or to the C4-thiazol moiety and investigated their effects on CDK9 potency and selectivity. One of the most selective compounds, 12u inhibits CDK9 with IC(50) = 7 nM and shows over 80-fold selectivity for CDK9 versus CDK2. X-ray crystal structures of 12u bound to CDK9 and CDK2 provide insights into the binding modes. This work, together with crystal structures of selected inhibitors in complex with both enzymes described in a companion paper, (34) provides a rationale for the observed SAR. 12u demonstrates potent anticancer activity against primary chronic lymphocytic leukemia cells with a therapeutic window 31- and 107-fold over those of normal B- and T-cells.

Targeting Mnks for cancer therapy

Deregulation of protein synthesis is a common event in human cancer and a key player in translational control is eIF4E. Elevated expression levels of eIF4E promote cancer development and progression. Recent findings suggest that eIF4E activity is a key determinant of the PI3K/Akt/mTOR and Ras/Raf/MEK/ERK mediated tumorigenic activity and targeting eIF4E should have a major impact on these pathways in human cancer. The function of eIF4E is modulated through phosphorylation of a conserved serine (Ser209) by Mnk1 and Mnk2 downstream of ERK. While the phosphorylation event is necessary for oncogenic transformation, it seems to be dispensable for normal development. Hence, pharmacologic Mnk inhibitors may provide non-toxic and effective anti-cancer strategy. Strong circumstantial evidence indicates that Mnk inhibition presents attractive therapeutic potential, but the lack of selective Mnk inhibitors has so far confounded pharmacological target validation and clinical development.

CDKI-71, a novel CDK9 inhibitor, is preferentially cytotoxic to cancer cells compared to flavopiridol

Cancer cells appear to depend heavily on antiapoptotic proteins for survival and so targeted inhibition of these proteins has therapeutic potential. One innovative strategy is to inhibit the cyclin-dependent kinases (CDKs) responsible for the regulation of RNA polymerase II (RNAPII). In our study, we investigated the detailed cellular mechanism of a novel small-molecule CDK inhibitor (CDKI-71) in cancer cell lines, primary leukemia cells, normal B - & T- cells, and embryonic lung fibroblasts and compared the cellular and molecular responses to the clinical CDK inhibitor, flavopiridol. Like flavopiridol, CDKI-71 displayed potent cytotoxicity and caspase-dependent apoptosis induction that were closely associated with the inhibition of RNAPII phosphorylation at serine-2. This was caused by effective targeting of cyclinT-CDK9 and resulted in the downstream inhibition of Mcl-1. No correlation between apoptosis and inhibition of cell-cycle CDKs 1 and 2 was observed. CDKI-71 showed a 10-fold increase in potency in tumor cell lines when compared to MRC-5 human fibroblast cells. Significantly, CDKI-71 also demonstrated potent anti-chronic lymphocytic leukemia activity with minimal toxicity in normal B- and T-cells. In contrast, flavopiridol showed little selectivity between cancer and normal cells. Here, we provide the first cell-based evidence that flavopiridol induces DNA double-strand breaks: a fact which may explain why flavopiridol has such a narrow therapeutic window in preclinical and clinical settings. Taken together, our data provide a rationale for the development of selective CDK inhibitors as therapeutic agents and CDKI-71 represents a promising lead in this context.

Synthesis and biological evaluation of benzyl styrylsulfonyl derivatives as potent anticancer mitotic inhibitors

We herein report the synthesis, biological activity and structure activity relationship of derivatives of benzylstyrylsulfone, benzylstyrylsulfine and benzylsulfonyl-N-phenylacetamide. A lead compound 7 represents a new class of mitotic inhibitors that demonstrates potent anti-proliferative activity and selectively induces cancer cell apoptosis while sparing non-transformed lung fibroblast.

Open repair of massive rotator cuff tears in patients aged sixty-five years or over: is it worthwhile?

The purpose of the study was to evaluate the functional outcome and identify possible preoperative prognostic factors in patients aged 65 years or over undergoing open repair for a massive (>5 cm) full-thickness rotator cuff tear. Patients were assessed after a mean of 48 months by an independent observer by use of the Constant score and the Oxford Shoulder Questionnaire. The outcome was excellent or good in 44% and poor in 23%. The patient satisfaction rate was 84%. Pain relief was obtained in 93%. We found three preoperative variables to be significantly associated with a poor outcome: female sex, duration of symptoms greater than 34 months before surgery, and American Society of Anesthesiologists grade. The results of our study suggest that appropriately selected patients who are aged 65 years or over with a massive full-thickness rotator cuff tear can be expected to have a good functional outcome and pain relief after repair.

Open repair of massive rotator cuff tears in patients aged sixty-five years or over: is it worthwhile?

The purpose of the study was to evaluate the functional outcome and identify possible preoperative prognostic factors in patients aged 65 years or over undergoing open repair for a massive (>5 cm) full-thickness rotator cuff tear. Patients were assessed after a mean of 48 months by an independent observer by use of the Constant score and the Oxford Shoulder Questionnaire. The outcome was excellent or good in 44% and poor in 23%. The patient satisfaction rate was 84%. Pain relief was obtained in 93%. We found three preoperative variables to be significantly associated with a poor outcome: female sex, duration of symptoms greater than 34 months before surgery, and American Society of Anesthesiologists grade. The results of our study suggest that appropriately selected patients who are aged 65 years or over with a massive full-thickness rotator cuff tear can be expected to have a good functional outcome and pain relief after repair.

Limb loss following the use of heparin. A lesson to be remembered

The optimal method of prophylaxis against venous thromboembolism after total hip replacement (THR) remains uncertain. Most surgeons use some form of pharmacological prophylaxis, most commonly heparin. The precise balance of the benefits and risks is unclear, and serious complications can occur. We describe a case of heparin-induced thrombocytopenia and thrombosis syndrome in a 62-year-old woman after THR.

LIMB LOSS FOLLOWING THE USE OF HEPARIN

The optimal method of prophylaxis against venous thromboembolism after total hip replacement (THR) remains uncertain. Most surgeons use some form of pharmacological prophylaxis, most commonly heparin. The precise balance of the benefits and risks is unclear, and serious complications can occur. We describe a case of heparin-induced thrombocytopenia and thrombosis syndrome in a 62-year-old woman after THR.

Traumatic asymmetrical bilateral hip dislocation in an adult

Bilateral hip dislocation occurring as a result of trauma is a rare condition. Simultaneous anterior and posterior traumatic dislocation of both hips is even more unusual. A case is reported of asymmetrical bilateral traumatic hip dislocation without an associated fracture of the pelvis or femur occurring in a young adult with no previous history of hip abnormality or ligamentous laxity. An unusual mechanism for this injury is also described.

Selection analyses of insertional mutants using subgenic-resolution arrays

We describe a method of genome-wide analysis of quantitative growth phenotypes using insertional mutagenesis and DNA microarrays. We applied the method to assess the fitness contributions of Escherichia coli gene domains under specific growth conditions. A transposon library was subjected to competitive growth selection in Luria-Bertani (LB) and in glucose minimal media. Transposon-containing genomic DNA fragments from the selected libraries were compared with the initial unselected transposon insertion library on DNA microarrays to identify insertions that affect fitness. Genes involved in the biosynthesis of nutrients not provided in the growth medium were found to be significantly enriched in the set of genes containing negatively selected insertions. The data also identify fitness contributions of several uncharacterized genes, including putative transcriptional regulators and enzymes. The applicability of this high-resolution array selection in other species is discussed.

Clinical and cost-effectiveness of continuous subcutaneous terbutaline versus oral tocolytics for treatment of recurrent preterm labor in twin gestations

OBJECTIVE

To compare the clinical and cost-effectiveness of treating recurrent preterm labor with continuous subcutaneous terbutaline versus oral tocolytics in twin gestations.

STUDY DESIGN

In a retrospective, matched-cohort design, twin pregnancies treated as outpatients with continuous subcutaneous terbutaline were identified from a perinatal database, then matched 1:1 by gestational age at recurrent preterm labor to those receiving oral tocolytics. There were 353 patients per treatment group. A cost model was used to compare antepartum hospital, nursery, and outpatient charges.

RESULTS

Infants of the subcutaneous terbutaline group had greater gestational age at delivery, higher birth weights, and less frequent neonatal intensive care unit admission. Charges for antepartum hospitalization and nursery were significantly less in the subcutaneous terbutaline group, while charges for outpatient services were less for the oral group. Mean total estimated charges were US$17,109 less for those receiving subcutaneous terbutaline.

CONCLUSION

Improved clinical outcomes and decreased nursery utilization suggest cost-effectiveness of outpatient continuous subcutaneous terbutaline versus oral tocolytics for the treatment of recurrent preterm labor.

Adherence to antibiotics prescribed in an accident and emergency department: the influence of consultation factors

The objective of this study was to investigate the extent of non-adherence to prescribed antibiotics and the relationship of non-adherence to consultation and attitudinal factors. Self-completion postal questionnaires were sent to 202 consecutive adult attenders to an accident and emergency (A&E) department who had been given antibiotics to take home, within a week of the A&E attendance. The questionnaire included a detailed log of dosing, two sections of eight questions each on the patients' perceptions of the consultation and of their attitudes to medicines in general, which were marked on Likert scales; and questions inviting free text answers. Efforts were made to maximize the response rate, and to contact a random sample of 10 non-responders to assess any non-response bias. The response rate was 56%. The non-responders sampled reported similar non-adherence to that of the responders. Of the 113 responders, 10 (9%) indicated that they had taken none of their prescribed medicines, and 25 (22%) that they had taken less than 80%. The most common pattern of non-adherence was early cessation. Two aspects of the consultation (expectations about a prescription, and that there were too many tablets) were related to adherence. In conclusion, this study suggests that the effectiveness of some A&E consultations is reduced by inadequate exploration of patients' concerns and expectations.

A comparison of gestational days gained with oral terbutaline versus continuous subcutaneous terbutaline in women with twin gestations

OBJECTIVE

To compare gestational days gained with oral versus subcutaneous terbutaline for maintenance tocolysis.

STUDY DESIGN

In retrospective fashion 386 women enrolled in an outpatient preterm labor identification program met the following criteria: twin gestation, development of threatened preterm labor resulting in treatment with oral terbutaline, and subsequent recurrence of threatened preterm labor resulting in treatment with continuous subcutaneous terbutaline. The primary outcome was gestational days gained with oral terbutaline versus gain with continuous subcutaneous terbutaline.

RESULTS

There were significantly more days gained during subcutaneous treatment than during oral treatment (34.0 +/- 19.8 versus 19.3 +/- 15.3 days). Thirty-three percent of desired prolongation was achieved with oral terbutaline, whereas 79% of desired prolongation was achieved with subcutaneous terbutaline (p < 0.001). Patients gained a mean of 53.4 +/- 21.4 days overall with outpatient tocolysis. The mean gestational age at delivery was 35.2 +/- 1.9 weeks.

CONCLUSION

Continuous subcutaneous terbutaline was superior to oral terbutaline in prolonging gestation in women with twin gestations.

Predicting BMI in young adults from childhood data using two approaches to modelling adiposity rebound

OBJECTIVE

To identify the age of adiposity rebound and the value of its associated BMI and examine their association with BMI at ages 18 and 21 y for males and females.

DESIGN

A longitudinal study of a large cohort of people born in Dunedin, New Zealand between 1972-1973.

SUBJECTS

Four hundred and seventy-four males and 448 females aged between birth and 21 y.

MEASUREMENTS

BMI was derived from measurements of weight and height made when the participants were born and at intervals from age 3-21 y.

RESULTS

When a random coefficients model was fitted to the data for those who had five or more measures of BMI between age 3 and age 18y, adiposity rebound occurred at 6.0 y of age for boys and 5.6y for girls. The values of BMI associated with these were 15.7 kg/m2 for boys and 15.5 kg/m2 for girls. The correlations between age at adiposity rebound and BMI at ages 18 and 21 y were between -0.72 and -0.65 for boys and -0.59 and -0.47 for girls. These were higher than those derived from fitting individual curves or from deriving the adiposity rebound from data collected up to age 11 y. The correlation between BMI at age 7y and BMI at ages 18 and 21 y were 0.70 and 0.61 for boys and 0.56 and 0.52 for girls. The correlations between measures of skeletal maturity at age 7y and adiposity rebound were statistically significant for boys but not for girls.

CONCLUSIONS

BMI in early adulthood was associated with both age of adiposity rebound and BMI at that age. As the correlations between BMI at age 7 y and BMI at ages 18 and 21 y were similar in magnitude, BMI at age 7 y may be a more practical way of predicting BMI in early adulthood.

Clinical issues surrounding the use of terbutaline sulfate for preterm labor

beta-mimetics have been prescribed by physicians to arrest or prevent premature labor for more than 20 years. Although not approved by the Food and Drug Administration (FDA) for tocolytic use, terbutaline sulfate has been the most widely prescribed beta-mimetic in the United States. Recently, the role of terbutaline in the treatment and prevention of preterm labor has been questioned by the FDA. Because the off-label use of drugs is a formally accepted practice in medicine when scientific studies support such use, we reviewed the currently available clinical literature on terbutaline use in various routes of delivery: intravenous, oral, and subcutaneous via infusion pump. This review describes the clinical evidence that supports the safe and effective use of terbutaline as a tocolytic agent in certain patient populations. Practicing physicians should continue to have unrestricted use of terbutaline for tocolysis as one of the few remaining therapeutic options remaining in the fight against preterm birth.

Regulation of amyloid precursor protein catabolism involves the mitogen-activated protein kinase signal transduction pathway

Catabolic processing of the amyloid precursor protein (APP) is subject to regulatory control by protein kinases. We hypothesized that this regulation involves sequential activation of the enzymes mitogen-activated protein kinase kinase (MEK) and extracellular signal-regulated protein kinase (ERK). In the present investigation, we provide evidence that MEK is critically involved in regulating APP processing by both nerve growth factor and phorbol esters. Western blot analysis of the soluble N-terminal APP derivative APPs demonstrated that the synthetic MEK inhibitor PD 98059 antagonized nerve growth factor stimulation of both APPs production and ERK activation in PC12 cells. Moreover, PD 98059 inhibited phorbol ester stimulation of APPs production and activation of ERK in both human embryonic kidney cells and cortical neurons. Furthermore, overexpression of a kinase-inactive MEK mutant inhibited phorbol ester stimulation of APP secretion and activation of ERK in human embryonic kidney cell lines. Most important, PD 98059 antagonized phorbol ester-mediated inhibition of Abeta secretion from cells overexpressing human APP695 carrying the "Swedish mutation." Taken together, these data indicate that MEK and ERK may be critically involved in protein kinase C and nerve growth factor regulation of APP processing. The mitogen-activated protein kinase cascade may provide a novel target for altering catabolic processing of APP.

The incidence of post dural puncture headache in children

One hundred and five children with malignant disease attended for lumbar puncture which was performed under general anaesthesia. A questionnaire was answered over the next three days to determine the incidence of post dural puncture headache Ninety-seven questionnaires were returned and the results show that no child aged under ten years developed a headache. Of the children aged 10-12 years, two out of seventeen developed a headache (11.8%). In children aged 13-18 years, five out of ten developed a headache (50%).

Growth suppression by p16ink4 requires functional retinoblastoma protein

p16ink4 has been implicated as a tumor suppressor that is lost from a variety of human tumors and human cell lines. p16ink4 specifically binds and inhibits the cyclin-dependent kinases 4 and 6. In vitro, these kinases can phosphorylate the product of the retinoblastoma tumor suppressor gene. Thus, p16ink4 could exert its function as tumor suppressor through inhibition of phosphorylation and functional inactivation of the retinoblastoma protein. Here we show that overexpression of p16ink4 in certain cell types will lead to an arrest in the G1 phase of the cell cycle. In addition, we show that p16ink4 can only suppress the growth of human cells that contain functional pRB. Moreover, we have compared the effect of p16ink4 expression on embryo fibroblasts from wild-type and RB homozygous mutant mice. Wild-type embryo fibroblasts are inhibited by p16ink4, whereas the RB nullizygous fibroblasts are not. These data not only show that the presence of pRB is crucial for growth suppression by p16ink4 but also indicate that the pRB is the critical target acted upon by cyclin D-dependent kinases in the G1 phase of the cell cycle.

Reversed-phase ion-pair high-performance liquid chromatographic determination of fluoroquinolones in human plasma

A simple and sensitive method is described for the determination of fluoroquinolones by HPLC on a C-18 column using fluorescence detection. Using a mobile phase of 25% (v/v) acetonitrile phosphate buffer (pH 2.0), adequate retention and separation among the solutes norfloxacin, amifloxacin, enoxacin, and pipemidic acid have been obtained using sodium lauryl sulphate as the pairing ion and tetrabutylammonium bromide as the counter ion. The chromatographic conditions selected have been used for the quantitation of norfloxacin, amifloxacin, and enoxacin in human plasma using pipemidic acid as the internal standard. A simple single-step protein precipitation procedure has been employed for pretreatment of plasma samples. The detection limits of the assay for enoxacin, amifloxacin, and norfloxacin are approximately 100, approximately 10, and approximately 20 ng/mL, respectively. The method has been employed for the determination of amifloxacin in plasma samples from a healthy volunteer following oral administration of a 400-mg amifloxacin capsule.