Intercellular Mechanisms of Therapeutic Resistance at the Tumor-Stromal Interface Using Ultra High-Plex Single-Cell Spatial Transcriptomics and Genetically-Engineered Tumoroids

PURPOSE/OBJECTIVE(S)

There is a major gap in knowledge regarding how intercellular interactions in the tumor microenvironment (TME) mediate therapeutic resistance. Achievement of this goal has been limited by a lack of (1) spatial context in dissociated single-cell methods; (2) single-cell resolution in spatial profiling approaches; (3) high quality data and yield with FFPE patient specimens; and (4) computational methods for ligand-receptor analyses that consider both gene expression and spatial coordinates.

MATERIALS/METHODS

We developed an innovative spatial biology paradigm that combines cutting-edge experimental and computational methods to enable high-resolution, spatially-guided discovery of critical mediators of therapeutic resistance. We applied this approach to dissect the single-cell spatial transcriptomic landscape of untreated vs. chemoradiotherapy-treated primary human pancreatic ductal adenocarcinoma (PDAC; n = 21) using ultra-high plex spatial molecular imaging (SMI) optimized for high-sensitivity, subcellular detection of up to 6000 gene transcripts in FFPE sections-an order of magnitude greater than contemporary methods.

RESULTS

We recovered over 1,000,000 high-quality single cells in situ representing more than 20 distinct cell types, including epithelial, immune, endothelial, endocrine, and diverse stromal cells. We developed an optimal transport-based computational method to infer cell-cell communication at the cancer-stromal interface. Treatment with chemoradiotherapy was associated with the largest increase in fibroblast-malignant interactions. Comparing the SMI data with orthogonal single-nucleus RNA-sequencing and digital spatial profiling data, we identified CLCF1-CNTFR as the fibroblast-malignant interaction most associated with resistance to chemoradiotherapy in PDAC. CLCF1 is a gp130-family cytokine that activates Jak-STAT signaling and acts as a potent neurotrophic factor. Notably, the CLCF1-CNTRF (fibroblast-malignant) interaction has prominent pro-oncogenic effects in lung adenocarcinoma and an engineered CNTFR decoy receptor with therapeutic potential has been developed. To functionally validate the role of the CLCF1-CNTFR (fibroblast-malignant) interaction in mediating resistance to cytotoxic therapy, we created CRISPR-engineered cancer-fibroblast tumoroids and modulated expression of this ligand-receptor pair. Pancreatic cancer cell viability in the presence of 5-fluorouracil was better maintained with increased CLCF1-CNTFR signaling.

CONCLUSION

In this study, we integrated ultra high-plex single-cell spatial transcriptomics, optimal transport ligand-receptor predictions, and genetically-engineered stromal tumoroids to identify and validate CLCF1-CNTFR as an important intercellular mechanism of resistance to chemoradiotherapy in PDAC-pioneering a paradigm for translating single-cell spatial biology to clinical oncology.

Abstract OT3-03-01: Open-label, single-arm study evaluating the antitumor activity and safety of niraparib as neoadjuvant treatment in patients with localized, HER2-negative, BRCA-mutant breast cancer

Background: Neoadjuvant chemotherapy is administered to patients with operable breast cancer to downstage the tumor to allow for less extensive surgery and to provide prognostic information about drug efficacy and risk of disease recurrence. Patients who achieve a pathological complete response (pCR) following neoadjuvant treatment have a more favorable outcome than patients with residual invasive disease. Single-agent poly(ADP-ribose) polymerase (PARP) inhibitors have clinical efficacy in BRCA-mutated breast cancer. Niraparib, a potent and selective PARP1/2 inhibitor, is approved for maintenance treatment of patients with recurrent ovarian cancer and has demonstrated strong antitumor activity in in vivo studies with BRCA1-mutant breast cancer. The objective of this study is to evaluate the antitumor activity of single-agent niraparib in the neoadjuvant treatment of patients with localized, human epidermal growth factor receptor 2 (HER2)-negative, BRCAmut breast cancer.

Trial Design: This is an open-label, single-arm pilot study with a target enrollment of 20 evaluable patients. Eligible patients are those ≥18 years old with histologically-confirmed HER2-negative localized breast cancer and either a BRCA1 or BRCA2 mutation (germline or somatic) and no prior anti-cancer therapies for the current malignancy. Patients will receive 200 mg of oral niraparib once daily for 2 months, after which they may either proceed directly to surgery or receive chemotherapy at the discretion of the physician. The primary endpoint is tumor response rate based on the change in tumor volume as measured by breast MRI after 2 months of treatment with niraparib; a response is defined as ≥30% reduction of tumor volume from baseline. Secondary endpoints include pCR rate, tumor response rate based on the change in tumor volume as measured by breast ultrasound, and safety and tolerability. Data will be summarized in a descriptive nature by frequency distributions (number and percentage of patients) for categorical variables and by the mean, median, and standard deviation for continuous variables. Tumor response rate will be tabulated together with its 95% binomial exact confidence interval.

Funding: TESARO, Inc., Waltham, MA, USA sponsored the study.

Citation Format: Han H, Hamilton E, Irie H, Isakoff S, Jelovac D, Liem A, Liu MC, Milillo A, Nangia J, Page D, Reeves J, Santa-Maria C, Duncan M, Graham JR, Chen J, Dezube BJ, Spring L. Open-label, single-arm study evaluating the antitumor activity and safety of niraparib as neoadjuvant treatment in patients with localized, HER2-negative, BRCA-mutant breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT3-03-01.

Safety of intravenous metoprolol use in unmonitored wards: a single-centre observational study

BACKGROUND AND AIM

This study aims to examine and quantify the risks associated with the use of intravenous metoprolol on unmonitored wards.

METHOD

This study was a retrospective single-centre observational study from 1 January 2009 to 31 December 2013. The study hospital was a 415-bed, private hospital in Melbourne, Victoria. The study population was all patients who received intravenous metoprolol on an unmonitored ward. The primary outcome measure was the rate of serious adverse events (SAE), defined as a complication of intravenous metoprolol resulting in transfer to a critical-care environment, a medical emergency team call or death.

RESULTS

Six hundred and nine patients received a total of 8260 doses of intravenous metoprolol. Seven cases were identified with a SAE deemed possibly related to beta-blocker use and there was one death. All SAE were hypotension, giving an overall rate of hypotension of 7/609 or 1.1% (95% confidence interval (CI), 0.5 to 2.4%) with a rate per dose delivered of 0.8/1000 doses (95% CI 0.3 to 1.7). The death occurred in a 94-year-old woman with abdominal sepsis. After case file review, consensus opinion deemed this to be unrelated to intravenous metoprolol.

CONCLUSION

The use of intravenous metoprolol on unmonitored wards appears to be safe. The complication rate was low, suggesting that this may be a sensible approach to the management of in-hospital populations at risk of beta-blocker withdrawal.

Periodontal health--challenges in restorative dentistry

As the population ages and life expectancy increases, clinicians today find themselves in the wake of an ever-growing demand for high-quality aesthetic dental treatment, by increasingly informed patients. The long-term success of both cosmetic and restorative dentistry is dependent on well designed restorations and the health of the periodontal tissues. Overhanging restorations, full crown restorations with poor marginal fit, and implant-supported prosthetics with inadequate hygiene access all increase the risk for periodontal sequelae and interproximal caries. When planning restorative treatment, consideration should be given to the restorative design, the need for hygiene access and the location of intended implants. In addition, the patient's manual dexterity and ability to manipulate oral hygiene aids is a crucial consideration, as is adequate access for the hygienist to manually debride and maintain the restorations.

The effects of high-fat diet, branched-chainamino acids and exercise on female C57BL/6 mouse Achilles tendon biomechanical properties

Objectives

The goals of this study were: 1) to determine if high-fat diet (HFD) feeding in female mice would negatively impact biomechanical and histologic consequences on the Achilles tendon and quadriceps muscle; and 2) to investigate whether exercise and branched-chain amino acid (BCAA) supplementation would affect these parameters or attenuate any negative consequences resulting from HFD consumption.

Methods

We examined the effects of 16 weeks of 60% HFD feeding, voluntary exercise (free choice wheel running) and BCAA administration in female C57BL/6 mice. The Achilles tendons and quadriceps muscles were removed at the end of the experiment and assessed histologically and biomechanically.

Results

HFD feeding significantly decreased the Achilles tendon modulus without histological alterations. BCAA administration significantly decreased the stiffness of Achilles tendons in the exercised normal diet mice. Exercise partially ameliorated both the weight gain and glucose levels in the HFD-fed mice, led to a significant decrease in the maximum load of the Achilles tendon, and an increase in the average fibril diameter of the quadriceps femoris muscle. There were significant correlations between body weight and several biomechanical properties, demonstrating the importance of controlling obesity for maintaining healthy tendon properties.

Conclusions

In summary, this study showed a significant impact of obesity and body weight on tendon biomechanical properties with limited effects of exercise and BCAAs.

Cite this article: Bone Joint Res 2013;2:186–92.

Cloning and pharmacological characterization of the dog P2X7 receptor

BACKGROUND AND PURPOSE

Human and rodent P2X7 receptors exhibit differences in their sensitivity to antagonists. In this study we have cloned and characterized the dog P2X7 receptor to determine if its antagonist sensitivity more closely resembles the human or rodent orthologues.

EXPERIMENTAL APPROACH

A cDNA encoding the dog P2X7 receptor was isolated from a dog heart cDNA library, expressed in U-2 OS cells using the BacMam viral expression system and characterized in electrophysiological, ethidium accumulation and radioligand binding studies. Native P2X7 receptors were examined by measuring ATP-stimulated interleukin-1beta release in dog and human whole blood.

KEY RESULTS

The dog P2X7 receptor was 595 amino acids long and exhibited high homology (>70%) to the human and rodent orthologues although it contained an additional threonine at position 284 and an amino acid deletion at position 538. ATP possessed low millimolar potency at dog P2X7 receptors. 2'-&3'-O-(4benzoylbenzoyl) ATP had slightly higher potency but was a partial agonist. Dog P2X7 receptors possessed relatively high affinity for a number of selective antagonists of the human P2X7 receptor although there were some differences in potency between the species. Compound affinities in human and dog blood exhibited a similar rank order of potency as observed in studies on the recombinant receptor although absolute potency was considerably lower.

CONCLUSIONS AND IMPLICATIONS

Dog recombinant and native P2X7 receptors display a number of pharmacological similarities to the human P2X7 receptor. Thus, dog may be a suitable species for assessing target-related toxicity of antagonists intended for evaluation in the clinic.

An open-label, multicenter, phase I/II study of AT-101 in combination with docetaxel (D) and prednisone (P) in men with castrate-resistant prostate cancer (CRPC)

5062

Background: Antiapoptotic Bcl-2 family proteins are overexpressed in CRPC and contribute to resistance to therapy. The oral pan-Bcl-2 inhibitor AT-101 (Bcl-2, Bcl-XL, Bcl-W, Mcl-1) is active as a single agent and in combination in in vitro and in vivo tumor models and as a single agent in CRPC. The Phase 1 portion of the study determined the recommended dose for phase II to be D (75mg/m2 q3weeks) in combination with P (5mg b.i.d. on days 1–21), and AT-101 at 40mg b.i.d. on days 1–3 of each 21-day cycle, and was previously reported. Methods: Men ≥18 years of age with chemotherapy-naïve CRPC (N = 36). Safety (NCI CTCAE v3.0) and efficacy (Bubley Criteria for PSA) were assessed at 3-wk intervals. Radiological assessments were performed at 6-wk intervals for pts with soft tissue disease and bone scans were performed after cycle 6 and at the completion of therapy. Results: 36 patients (pts) have been enrolled in the study. Twenty-four (67%) pts achieved a partial response (PR) (>50% PSA decline), and 26 (72%) pts treated had at least a 30% decrease in PSA level. Nine of 19 pts (47%) with measurable disease had a PR. One PR was unconfirmed per RECIST. Thirteen pts (36%) completed >10 cycles of therapy (range 2–24) thus far. Four pts remains active. Safety data is available for 31 pts. The most common (>20%) Adverse Events (AEs) include: fatigue (68%), nausea (52%), diarrhea (45%), alopecia (32%), constipation and dysgeusia (26%), and neutropenia and vomiting (26%). Neutropenia was the only gr. 4 event occurring in more than one pt (3pts). Serious Adverse Events (SAEs) considered related were reported in 5 pts (16%). The only SAEs reported in 2 or more pts were urinary tract infection (3 pts) and deep vein thrombosis (2 pts) and none were considered related. No ileus has been reported. Conclusions: AT-101 when given in combination with D/P is well tolerated and shows preliminary evidence of efficacy in pts with CRPC. A randomized trial is ongoing.

[Table: see text]

Preliminary report of an open-label, multicenter, phase I/II study of AT-101 in combination with docetaxel (D) and prednisone (P) in men with docetaxel refractory prostate cancer

5145

Background: Antiapoptotic Bcl-2 family proteins are overexpressed in castrate resistant prostate cancer (CRPC) and contribute to resistance to therapy. AT-101 is a pan-Bcl-2 inhibitor (Bcl-2, Bcl-XL, Bcl-W, and Mcl-1) and potent inducer of proapoptotic proteins. AT-101 is active as a single agent and in combinations with standard therapies in in vitro and in vivo tumor models, as a single agent in a phase II trial in CRPC, and in combination with D/P as first-line therapy in CRPC, as demonstrated by declines in PSA and RECIST responses. Methods: Men ≥18 years of age with docetaxel-refractory CRPC were eligible. Patients (pts) must have PSA progression per the Bubley criteria or documented disease progression while receiving prior D/P therapy. Pts (n = 40) were treated with D (75 mg/m2 day 1), P (5mg b.i.d. on days 1–21) and AT-101 40mg b.i.d. on days 1–3 of each 21-day cycle. Safety (NCI CTCAE v3.0) and efficacy (Bubley Criteria for PSA) were assessed at 3-wk intervals. Radiological assessments were performed at 6-wk intervals for pts with soft tissue disease and bone scans were performed after cycle 6 and at the completion of therapy. Results: Efficacy data was available on 34 pts. Thirty-five percent (12/34) of pts treated had at least a 30% decrease in PSA level and 18% (6/34) of pts achieved a >50% PSA decline. Twenty one of 34 pts included in this analysis had measurable disease. Five pts (24%) with measurable disease had a PR or CR by RECIST criteria and one additional patient had tumor shrinkage of 29%. Two (2) RECIST PRs are unconfirmed. Thus far, 3 pts have been on therapy for 6 months or more and 15 pts remain on study. Safety data was available on 22 pts. The most common (>20%) adverse events (AEs) included fatigue (55%), anorexia, including weight decreased (45%), diarrhea and nausea (27%), vomiting and neutropenia (23%). The grade 3/4 AEs occurring in more than 1 pt were: neutropenia (5), anemia, anorexia, dyspnea and leukopenia (2 pts each). One partial small bowel obstruction was the only related, serious adverse event (SAE) reported to date. Conclusions: This data supports that AT-101 can be administered safely with D/P in pts with CRPC who are docetaxel-refractory. Durable PSA and RECIST responses were observed.

[Table: see text]

Systems biology of the neurospora biological clock

A major challenge of systems biology is explaining complex traits, such as the biological clock, in terms of the kinetics of macromolecules. The clock poses at least four challenges for systems biology: (i) identifying the genetic network to explain the clock mechanism quantitatively; (ii) specifying the clock's functional connection to a thousand or more genes and their products in the genome; (iii) explaining the clock's response to light and other environmental cues; and (iv) explaining how the clock's genetic network evolves. Here, the authors illustrate an approach to these problems by fitting an ensemble of genetic networks to microarray data derived from oligonucleotide arrays with approximately all 11 000 Neurospora crassa genes represented. A promising genetic network for the clock mechanism is identified.

The complete genome sequence, organization and affinities of carrot red leaf virus

A sequence of 5723 nucleotides (GenBank accession number: AY695933) is reported for the RNA genome of an isolate of Carrot red leaf virus (CtRLV). The sequence is predicted to contain six large open reading frames and non coding sequences of 28 nucleotides at the 5' end, 110 nucleotides at the 3' end, and 215 nucleotides between the two main blocks of coding sequences. The 5' coding region encodes two polypeptides with calculated molecular masses (Mr) of 28.6 kDa (P0) and 68.2 kDa (P1) that overlap in different reading frames. Circumstantially, the third ORF in the 5' block is putatively translated by frameshift read-through to yield a polypeptide (P1 + P2) with a calculated Mr of 116.9 kDa. Frameshifting is predicted at a "shifty" sequence (GGGAAAC; nt 1523-1529) also found in most members of the genus Polerovirus. The C-terminal region of the 116.9 kDa polypeptide includes the consensus sequence for the viral RNA-directed RNA polymerase. The 3' block of coding sequence defines three putative polypeptides of: 23.0 kDa (P3), 21.3 kDa (P4, in a different reading frame) and 77.2 kDa (P3 + P5, by read-through of P3) respectively. From the genome structure of CtRLV, it is suggested that this virus belongs to the genus Polerovirus, rather than either the genus Luteovirus or the genus Enamovirus.

Construction and properties of a gene-silencing vector based on Poplar mosaic virus (genus Carlavirus)

A gene-silencing vector based on a full-length genomic clone of Poplar mosaic virus (PopMV) was constructed, with coat protein and movement protein genes removed, and containing instead, the coding sequence for green fluorescent protein (GFP). This paper demonstrates that the PopMV-derived gene-silencing vector was able to silence GFP expression in GFP transgenic Nicotiana benthamiana plants. The full-length genome of an Oxford isolate of PopMV (PV275) was cloned and sequenced. A full-length PopMV clone, under transcriptional control of the 35SCaMV promoter was then constructed, and the clone was able to replicate locally in Nicotiana species. Several autonomous plant RNA and DNA viruses have been converted into vectors and implemented for virus-induced gene-silencing (VIGS) of transgenes and endogenous genes [Burton, R., Gibeaut, D., Bacic, A., Findlay, K., Roberts, K., Hamilton, A., Baulcombe, D., Fincher, G., 2000. Virus-induced silencing of a plant cellulose synthase gene. Plant Cell 12, 691-706; Dalmay, T., Horsefield, R., Braunstein, T.H., Baulcombe, D.C., 2001. SDE3 encodes an RNA helicase required for post-transcriptional gene silencing in Arabidopsis. EMBO J. 20, 2069-2077; Gossele, V., Fache, I., Meulewaeter, F., Cornelissen, M., Metzlaff, M., 2002. SVISS--a novel transient gene silencing system for gene function discovery and validation in tobacco plants. Plant J. 32, 859-866; Holzberg, S., Brosio, P., Gross, C., Pogue, G.P., 2002. Barley stripe mosaic virus-induced gene silencing in a monocot plant. Plant J. 30, 315-327; Ratcliff, F., Martin-Hernandez, A., Baulcombe, D., 2000. Tobacco rattle virus as a vector for analysis of gene function by silencing. Plant J. 25, 237-245; Ruiz, M., Vionnet, O., Baulcombe, D., 1998. Initiation and maintenance of virus-induced gene silencing. Plant Cell 10, 937-946]. The use of a virus that naturally infects trees as a gene-silencing vector has not been demonstrated before. The ability to systemically silence a plant transgene following the production of a gene-silencing signal from a locally replicating viral-construct derived from a carlavirus has not to our knowledge been shown before.

Investigation into the thermal distribution of microwave helical antennas designed for the treatment of Barrett's oesophagus

A set of helical microwave antennas was designed to investigate their potential use in thermal therapy of Barrett's oesophagus. The antennas had a diameter of up to 3.3 mm and various lengths between 20 and 37 mm; these were designed to operate at 915 MHz. Sets of polytetrafluoroethylene (PTFE) formers were constructed to improve the repeatability and reproducibility of the helix manufacture. Small diameter copper wire was wound over the formers and connected to the coaxial cable at the inner and outer conductor junctions. The power deposition profiles of the antennas were measured in a muscle-equivalent phantom using an infrared camera. The effects of antenna length and coil spacing were characterized. It was observed that uniform temperature profiles along the antenna length were achieved with a length of wire of 99 mm +/- 2 mm. The effective heating length (length of the antenna that exhibits > 50% of the maximum temperature rise) was comparable to the antenna length. The radial penetration depth of 50% of the antenna surface temperature for the optimum 20 mm antenna was 2.5 mm from the antenna outer surface.

HER2 as a prognostic and predictive marker for breast cancer

In recent years investigators have looked at the human epidermal growth factor receptor-2 (HER2), which is overexpressed in 20%-30% of breast cancer patients, with regard to its role as a prognostic and predictive factor. Although many studies have suggested that HER2 overexpression may be associated with a poor clinical outcome, other studies have not fully supported this observation. The inconsistencies between studies may be due in part to discrepancies between different HER2 testing methods. To overcome this problem, a radioimmunohistochemical method was developed to quantitatively measure HER2 overexpression levels in breast tumor samples. The application of this method demonstrated that 85% of all breast tumor samples expressed HER2 at levels greater than normal. Of these, 23% expressed HER2 at levels between 45 and 480 times greater than normal, and this was associated with poor clinical outcome. The investigation of HER2 status as a predictor of response to therapy has also yielded many conflicting results. Overall, it appears that HER2 overexpression may correlate with resistance to hormonal therapy, sensitivity to anthracycline-based chemotherapy and resistance to CMF. With the development of targeted anti-HER2 therapies, assessment of HER2 status will be important in stratifying patients to the most appropriate treatment regimens.

The potential of diffuse reflectance spectroscopy for the determination of carbon inventories in soils

Investigations have shown that near- and mid-infrared reflectance spectroscopy can accurately determine organic-C in soil. Efforts have also demonstrated that both can differentiate between organic and inorganic-C in soils, but the mid-infrared produces more accurate calibrations. Nevertheless, the greatest benefit would come with in situ determinations where factors such as particle size, sample heterogeneity and moisture can be important. While the variations in large (> 20 mesh) particle size can adversely effect calibration accuracy, efforts have demonstrated that the scanning of larger amounts of sample can overcome this, but the effects of moisture have not been fully explored. While under in situ conditions C distribution and sample heterogeneity are a problem for any analytical method, the rapid analysis possible with spectroscopic techniques will allow many more samples to be analyzed. In conclusion, near- and mid-infrared spectroscopy have great potential for providing the C values needed for C sequestration studies.

The value of the human epidermal growth factor receptor-2 (HER2) as a prognostic marker

The prognosis for patients with breast cancer is determined by well-established pathological features associated with biological aggressiveness, histological grade, tumour size and nodal involvement. These remain the key determinants, despite the identification of numerous other potential biological markers. The use of prognostic indices, such as the Nottingham Prognostic Index (NPI), which combines and weights these factors, enables clinicians to predict outcome with a certain amount of accuracy. Approximately 20-30% of breast cancers express very high quantities of the human epidermal growth factor receptor-2 (HER2) protein and this is almost always associated with gene amplification. With the use of sensitive techniques, such as the radio-immunohistochemical method (rIHC) described herein, to quantify HER2 protein levels, up to a further 50% of such cancers will be found to express the HER2 receptor at least 4-fold higher than normal breast cells. Adding HER2 expression to the NPI helps to determine more accurately the prognosis for individual patients, particularly those with node-negative disease. Overall, the main value of HER2 measurement is likely to be in the prediction of response to therapies targeting the HER2 gene and protein.

The value of the human epidermal growth factor receptor-2 (HER2) as a prognostic marker

The prognosis for patients with breast cancer is determined by well-established pathological features associated with biological aggressiveness, histological grade, tumour size and nodal involvement. These remain the key determinants, despite the identification of numerous other potential biological markers. The use of prognostic indices, such as the Nottingham Prognostic Index (NPI), which combines and weights these factors, enables clinicians to predict outcome with a certain amount of accuracy. Approximately 20-30% of breast cancers express very high quantities of the human epidermal growth factor receptor-2 (HER2) protein and this is almost always associated with gene amplification. With the use of sensitive techniques, such as the radio-immunohistochemical method (rIHC) described herein, to quantify HER2 protein levels, up to a further 50% of such cancers will be found to express the HER2 receptor at least 4-fold higher than normal breast cells. Adding HER2 expression to the NPI helps to determine more accurately the prognosis for individual patients, particularly those with node-negative disease. Overall, the main value of HER2 measurement is likely to be in the prediction of response to therapies targeting the HER2 gene and protein.

High throughput fluorescence polarization: a homogeneous alternative to radioligand binding for cell surface receptors

High throughput fluorescence polarization (FP) assays are described that offer a nonradioactive, homogeneous, and low-cost alternative to radioligand binding assays for cell surface receptors (G protein-coupled receptors and ligand-gated ion channels). FP assays were shown to work across a range of both peptide (vasopressin V1a and delta-opioid) and nonpeptide (beta1-adrenoceptor, 5-hydroxytryptamine3) receptors. Structure-activity relationships were investigated at beta1-receptors and were found to be consistent with radioligand binding assays. FP was shown to tolerate up to 5% DMSO with no loss in sensitivity or signal window. From a random set of 1,280 compounds, 1.9% were found to significantly interfere with FP measurement. If fluorescent or quenching compounds were eliminated (3% of all compounds), less than 0.4% of compounds were found to interfere with FP measurement. Assays could be run in 384-well plates with little loss of signal window or sensitivity compared to 96-well plate assays. New advances in FP measurement have therefore enabled FP to offer a high throughput alternative to radioligand binding for cell surface receptors.

Knowledge about the assessment and management of undernutrition: a pilot questionnaire in a UK teaching hospital

BACKGROUND & AIMS

The detection, prevention and treatment of undernutrition in hospitals is often poor. This study assesses the knowledge about undernutrition of staff in a UK teaching hospital.

METHODS

Twenty nine doctors, 65 final year medical students, 45 nurses, 11 dietitians, and 11 pharmacists anonymously completed a questionnaire of 20 multiple choice questions. One of five possible answers was considered correct. Twelve questions were about adult nutritional assessment and requirements, five about oral/enteral nutrition and three about parenteral nutrition.

RESULTS

Dietitians scored significantly more (median 16) than the other groups (doctors: seven, medical students: eight, nurses: seven and pharmacists: nine) (P < 0.0001). Medical students scored more than doctors (P < 0.001). Examples of areas in which knowledge could be improved are: 67% respondents thought the prevalence of hospital undernutrition to be less than 30%. While 91% of respondents correctly chose a well 70 kg man to need about 2000 kcal/day, only 23% knew that approximately the same amount was needed for a febrile post-operative patient. Sixteen percent knew antibiotic treatment to be the most common reason for enteral feeding-related diarrhoea.

CONCLUSIONS

Knowledge about the assessment and management of undernutrition among doctors, medical students, nurses and pharmacists was poor. This questionnaire provides a framework for teaching and auditing the effectiveness of an educational program.

Are long hours and hard work detrimental to end-clerkship examination scores?

BACKGROUND

Third-year medical students' complaints focus on the number of hours worked and subsequent lack of study time among three general surgery blocks. We hypothesize that this difference between the surgical blocks does not adversely influence student examination scores.

METHODS

Student scores for the academic years 1996-97 to 1997-98 for the National Board of Medical Examiners (NBME) surgery subtests were compiled. A comparison of two "slow" general surgery blocks (B/C) with one "busy" block (A) was made using a two-tailed t test. A multiple regression analysis was also employed. Finally, United States Medical Licensing Examination (USMLE) part I scores were used to determine equivalency of groups.

RESULTS

No significant difference existed between block A and blocks B/C in USMLE part I and NBME (P = 0.35 and 0.16 respectively). However, USMLE and rotation sequence influenced NBME scores (P < 0.001).

CONCLUSION

The data suggest that no difference exists in examination scores between students assigned to a busy general surgery block versus those students assigned to slow blocks.

Comparison of single-dose oral granisetron versus intravenous ondansetron in the prevention of nausea and vomiting induced by moderately emetogenic chemotherapy: a multicenter, double-blind, randomized parallel study

PURPOSE

The antiemetic effectiveness and safety of single-dose oral granisetron were compared with intravenous (I.V.) ondansetron in chemotherapy-naive patients who received moderately emetogenic chemotherapy.

PATIENTS AND METHODS

In this double-blind, parallel-group study, patients naive to emetogenic chemotherapy (N = 1,085) who were scheduled to receive cyclophosphamide- (500 to 1,200 mg/m2) or carboplatin (> or = 300 mg/m2) based chemotherapy, were randomized to receive either oral granisetron (n = 542) or I.V. ondansetron (n = 543). Efficacy assessments included the proportion of patients in each treatment group with total control over the 24 and 48 hours following chemotherapy initiation, as well as incidence and severity of nausea and emesis and use of antiemetic rescue medication. Prophylactic corticosteroids were allowed. Safety assessment was based on patients' reports of adverse experiences.

RESULTS

Approximately 80% of patients received prophylactic corticosteroids. Single-dose oral granisetron (2 mg) and I.V. ondansetron (32 mg) resulted in equivalent levels of total emetic control during the first 48 hours after chemotherapy. The proportion of nausea- and emesis-free patients at 24 and 48 hours were also approximately equivalent. The most commonly reported adverse experiences were headache, asthenia, and constipation. More patients who received ondonsetron than granisetron reported dizziness (9.6% v 5.4%, respectively; P = .011) and abnormal vision (4.2% v 0.6%, respectively; P < .001).

CONCLUSION

A single oral dose of granisetron (2 mg) resulted in equivalent levels of antiemetic protection as I.V. ondansetron (32 mg). Both agents were well tolerated, although more dizziness and abnormal vision were reported with ondansetron. Because the two antiemetic regimens exhibited equivalent efficacies, additional factors such as convenience and cost of therapy should be considered.

Renal replacement therapy in the ICU: the Australian experience

The structure of health care drives medical practice in a powerful way, shaping choices of therapy and approaches, and influencing scientific evidence. The Australian experience with continuous renal replacement therapy (CRRT) confirms the importance of structure. A public health system like that of Australia's contains the following variables: well-developed intensive care tradition and expertise, a dominant "closed" intensive care unit (ICU) model, well-developed training of intensive care nurses with established one-to-one nurse-patient ratios, salaried medical practitioners, overworked general dialysis units with inadequate nursing resources, and lack of fee-for-service incentive for nephrologists to see ICU patients with acute renal failure. The likely outcome of such a system is for CRRT to be run by intensive care staff. As shown by a recent regional survey, this approach, although somewhat unique, is dominant and appears to work well with excellent clinical results and constant clinical research output.

Who should manage CRRT in the ICU? The intensivist's viewpoint

The arrival of continuous renal replacement therapy (CRRT) has given the intensivist and the intensive care nurse the opportunity to treat acute renal failure (ARF) independently by giving them the necessary technology and taking CRRT away from absolute nephrological control. This structural shift has created a controversy between those countries where control of CRRT has completely shifted to the intensivist and those countries where nephrological input is still dominant. The argument in favor of intensivist-driven CRRT rests upon several observations, including the fact that therapy is continuous, as is the presence of the intensivist in the intensive care unit (ICU). Critically ill patients require rapid changes in treatment that are best directed by physicians who are at the bedside all the time. CRRT must be seen within the totality of patient care, and the intensivist can see the larger picture more accurately. Intensivists are successfully performing more and more procedures that were previously seen as part of other specialties and, last but not least, "closed" models of ICU care appear to work best. Australian intensivists have taken up CRRT from the start and now control it. Patient outcomes under such a system, as reported here, are above average, and confirm the effectiveness of such an approach.