PROTACs Targeting BRM (SMARCA2) Afford Selective In Vivo Degradation over BRG1 (SMARCA4) and Are Active in BRG1 Mutant Xenograft Tumor Models

The identification of VHL-binding proteolysis targeting chimeras (PROTACs) that potently degrade the BRM protein (also known as SMARCA2) in SW1573 cell-based experiments is described. These molecules exhibit between 10- and 100-fold degradation selectivity for BRM over the closely related paralog protein BRG1 (SMARCA4). They also selectively impair the proliferation of the H1944 "BRG1-mutant" NSCLC cell line, which lacks functional BRG1 protein and is thus highly dependent on BRM for growth, relative to the wild-type Calu6 line. In vivo experiments performed with a subset of compounds identified PROTACs that potently and selectively degraded BRM in the Calu6 and/or the HCC2302 BRG1 mutant NSCLC xenograft models and also afforded antitumor efficacy in the latter system. Subsequent PK/PD analysis established a need to achieve strong BRM degradation (>95%) in order to trigger meaningful antitumor activity in vivo. Intratumor quantitation of mRNA associated with two genes whose transcription was controlled by BRM (PLAU and KRT80) also supported this conclusion.

Identification of GDC-1971 (RLY-1971), a SHP2 Inhibitor Designed for the Treatment of Solid Tumors

Protein tyrosine phosphatase SHP2 mediates RAS-driven MAPK signaling and has emerged in recent years as a target of interest in oncology, both for treating with a single agent and in combination with a KRAS inhibitor. We were drawn to the pharmacological potential of SHP2 inhibition, especially following the initial observation that drug-like compounds could bind an allosteric site and enforce a closed, inactive state of the enzyme. Here, we describe the identification and characterization of GDC-1971 (formerly RLY-1971), a SHP2 inhibitor currently in clinical trials in combination with KRAS G12C inhibitor divarasib (GDC-6036) for the treatment of solid tumors driven by a KRAS G12C mutation.

Descriptive analysis of poisoning cases involving attention deficit hyperactivity disorder medications in Hong Kong

INTRODUCTION

The number of poisoning cases involving attention deficit hyperactivity disorder (ADHD) medications has reportedly risen with their increased use. However, there is limited relevant evidence from Asia. We analysed the characteristics of poisoning events involving these medications in Hong Kong.

METHODS

We retrieved data regarding ADHD medication-related poisoning cases from the Hong Kong Poison Information Centre and conducted a descriptive analysis of the demographic information and poisoning information including sources of cases, exposure reason, exposure location, and outcome. The HKPIC data were linked with the Hospital Authority Clinical Data Analysis and Reporting System (CDARS) via de-identified Accident and Emergency numbers of public hospitals to investigate clinical characteristics. We also retrieved ADHD medication prescription records from the CDARS, then compared trends between poisoning cases and ADHD medication use.

RESULTS

We identified 72 poisoning cases involving ADHD medications between 2009 and 2019, of which approximately 70% occurred in the affected individual's residence; most were intentional poisoning events (65.3%). No statistically significant association was observed between ADHD medication prescription trends and poisoning events involving ADHD medications. Of the 66 cases (91.7%) successfully linked to CDARS, 40 (60.6%) occurred in individuals with ADHD (median age: 14 years); 26 (39.4%) occurred in individuals who lacked ADHD (median age: 33 years) but displayed higher rates of other mental disorders including depression and anxiety.

CONCLUSION

No significant correlation was evident between ADHD medication prescriptions and poisoning events involving ADHD medications. However, medication management and caregiver education must be emphasised to prevent potential poisoning events.

Assessment of KRAS G12C Target Engagement by a Covalent Inhibitor in Tumor Biopsies Using an Ultra-Sensitive Immunoaffinity 2D-LC-MS/MS Approach

KRAS is one of the most frequently mutated oncogenes, with KRAS G12C recently becoming an actionable target for small molecule intervention. GDC-6036 is an investigational KRAS G12C inhibitor that acts by irreversibly binding to the switch II pocket of KRAS G12C when in the inactive GDP-bound state, thereby blocking GTP binding and activation. Assessing target engagement is an essential component of clinical drug development, helping to demonstrate mechanistic activity, guide dose selection, understand pharmacodynamics as it relates to clinical response, and explore resistance. Here, we report the development of an ultra-sensitive approach for assessing KRAS G12C engagement. Immunoaffinity enrichment with a commercially available anti-RAS antibody was combined with a targeted 2D-LC-MS/MS technique to quantify both free and GDC-6036-bound KRAS G12C proteins. A KRAS G12C-positive non-small cell lung cancer xenograft model was dosed with GDC-6036 to assess the feasibility of this assay for analyzing small core needle biopsies. As predicted, dose-dependent KRAS G12C engagement was observed. To date, a sensitivity of 0.08 fmol/μg of total protein has been achieved for both free and GDC-6036-bound KRAS G12C with as little as 4 μg of total protein extracted from human tumor samples. This sub-fmol/μg level of sensitivity provides a powerful potential approach to assess covalent inhibitor target engagement at the site of action using core needle tumor biopsies from clinical studies.

No decrease in incidence of arthroscopic meniscectomy in a Canadian province

PURPOSE

Arthroscopic meniscectomy (APM) is the most common procedure in orthopedic surgery, despite increasing evidence questioning its benefit over conservative management for treatment of degenerative meniscal tears. The purpose of this study is to determine the epidemiology and trends of APM in Saskatchewan, a Canadian province, over a 20 year period.

METHODS

Physician billing codes were used to identify patients who underwent APM in Saskatchewan between January 1, 1998 and December 31, 2017. Records were obtained from eHealth Saskatchewan, a provincial health database. Data was analyzed for overall incidence and age-specific trends of APM.

RESULTS

A total of 35,099 APMs were performed during the study period. The population of Saskatchewan ranged from 992,314 to 1,150,782 (median 1,017,368) during this time interval, with 81 orthopedic surgeons performing APM. Overall incidence rate of APM did not change significantly over time. No decrease was observed in patients presumed to have degenerative tears (≥ 50 years). The number of meniscectomies in patients ≥ 50 years was significantly greater during the second decade of study compared to the first (OR 1.48, p < 0.01). Conversely, the increase in incidence rate among older patients was not statistically significant (R² = 0.125, n.s.).

CONCLUSION

Overall incidence rate of APM in Saskatchewan has not decreased during the last 20 years. Furthermore, APM frequency increased over time for individuals ≥ 50 years. Several regional factors may have contributed to these findings, including the large proportion of Saskatchewan residents engaged in physically demanding work and barriers to accessing physiotherapy services. Given recent evidence disputing the benefit of APM over conservative measures, this study highlights the need for improved dissemination of evidence, as well as the importance of an individualized treatment plan to address patient-specific factors.

LEVEL OF EVIDENCE

Level IV.

Scleral-fixated intraocular lens implants-evolution of surgical techniques and future developments

Varied options are available for the implantation of secondary intraocular lens implants in the absence of zonular or capsular support. Loss of the capsule can occur in the context of complicated cataract surgery, trauma or inherited conditions such as Marfan syndrome or pseudoexfoliation. Approaches to overcome this include optical measures such as the use of spectacles or contact lenses, and surgical therapy incorporating the use of anterior chamber, iris-fixated or scleral-fixated lenses. Surgical techniques to implant scleral-fixated lenses have undergone various modifications, since the first publication of sutured intrascleral fixation described in the 1980s. However, despite the advances in surgical techniques, studies are limited either by their retrospective nature, small sample size and most importantly small duration of follow-up. This comprehensive review aims to amalgamate the evolution of various surgical techniques with regards to intrascleral lens fixation and suggests areas for future development.

Short- and potential long-term adverse health outcomes of COVID-19: a rapid review

The coronavirus disease 2019 (COVID-19) pandemic has resulted in millions of patients infected worldwide and indirectly affecting even more individuals through disruption of daily living. Long-term adverse outcomes have been reported with similar diseases from other coronaviruses, namely Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). Emerging evidence suggests that COVID-19 adversely affects different systems in the human body. This review summarizes the current evidence on the short-term adverse health outcomes and assesses the risk of potential long-term adverse outcomes of COVID-19. Major adverse outcomes were found to affect different body systems: immune system (including but not limited to Guillain-Barré syndrome and paediatric inflammatory multisystem syndrome), respiratory system (lung fibrosis and pulmonary thromboembolism), cardiovascular system (cardiomyopathy and coagulopathy), neurological system (sensory dysfunction and stroke), as well as cutaneous and gastrointestinal manifestations, impaired hepatic and renal function. Mental health in patients with COVID-19 was also found to be adversely affected. The burden of caring for COVID-19 survivors is likely to be huge. Therefore, it is important for policy makers to develop comprehensive strategies in providing resources and capacity in the healthcare system. Future epidemiological studies are needed to further investigate the long-term impact on COVID-19 survivors.

Timing of syrinx reduction and stabilization after posterior fossa decompression for pediatric Chiari malformation type I

OBJECTIVE

The aim of this study was to determine the timeline of syrinx regression and to identify factors mitigating syrinx resolution in pediatric patients with Chiari malformation type I (CM-I) undergoing posterior fossa decompression (PFD).

METHODS

The authors conducted a retrospective review of records from pediatric patients (< 18 years old) undergoing PFD for the treatment of CM-I/syringomyelia (SM) between 1998 and 2015. Patient demographic, clinical, radiological, and surgical variables were collected and analyzed. Radiological information was reviewed at 4 time points: 1) pre-PFD, 2) within 6 months post-PFD, 3) within 12 months post-PFD, and 4) at maximum available follow-up. Syrinx regression was defined as ≥ 50% decrease in the maximal anteroposterior syrinx diameter (MSD). The time to syrinx regression was determined using Kaplan-Meier analysis. Multivariate analysis was conducted using a Cox proportional hazards model to determine the association between preoperative, clinical, and surgery-related factors and syrinx regression.

RESULTS

The authors identified 85 patients with CM-I/SM who underwent PFD. Within 3 months post-PFD, the mean MSD regressed from 8.1 ± 3.4 mm (preoperatively) to 5.6 ± 2.9 mm within 3 months post-PFD. Seventy patients (82.4%) achieved ≥ 50% regression in MSD. The median time to ≥ 50% regression in MSD was 8 months (95% CI 4.2-11.8 months). Using a risk-adjusted multivariable Cox proportional hazards model, the patients who underwent tonsil coagulation (n = 20) had a higher likelihood of achieving ≥ 50% syrinx regression in a shorter time (HR 2.86, 95% CI 1.2-6.9; p = 0.02). Thirty-six (75%) of 45 patients had improvement in headache at 2.9 months (IQR 1.5-4.4 months).

CONCLUSIONS

The maximum reduction in syrinx size can be expected within 3 months after PFD for patients with CM-I and a syrinx; however, the syringes continue to regress over time. Tonsil coagulation was associated with early syrinx regression in this cohort. However, the role of surgical maneuvers such as tonsil coagulation and arachnoid veil identification and sectioning in the overall role of CM-I surgery remains unclear.

Risk of Periprosthetic Joint Infection in Patients With Multiple Arthroplasties

BACKGROUND

Risk of subsequent periprosthetic joint infection (PJI) in a second prosthetic joint following initial PJI has been shown to be 19%-20%. We sought to identify (1) the risk of developing a second PJI for our patients with multiple prosthetic joints and (2) the effect of bacteremia on development of a subsequent PJI.

METHODS

We retrospectively reviewed all patients treated surgically for PJI by a single surgeon from 2003 to 2014. Time between initial and subsequent infection, bacteremia, and risk factors for PJI were identified.

RESULTS

Of 167 patients treated for PJI, 76 had multiple prosthetic joints. Thirteen percent (10/76) developed a PJI in a second location. Excluding simultaneous infections, the rate was 8.3% (6/72), despite having a 57% incidence of immunosuppression, diabetes, renal failure, smoking, or steroid use. Average follow-up for patients with 1 PJI was 4.6 years (range 0.03-13.6). Seventy percent (7/10) of patients with multiple infections were bacteremic at the time of initial infection compared to 18.1% (12/66) of patients with a single infection (P = .0004). Excluding the 4 simultaneous infections (all bacteremic), the risk of developing an infection in a second joint was 20% if bacteremic and 5.2% if not bacteremic.

CONCLUSION

Our study identified the risk of developing a subsequent PJI to be one half of previous studies. Bacteremia at the time of PJI is an important factor for developing subsequent PJI. Multiple prosthetic joints may be less hazardous than previously thought for patients with PJI suggesting that suppressive antibiotics may only be necessary in cases with bacteremia.

Unplanned readmission within 90 days after pediatric neurosurgery

OBJECTIVE Readmission and return to operating room after surgery are increasingly being used as a proxy for quality of care. Nearly 60% of these readmissions are unplanned, which translates into billions of dollars in health care costs. The authors set out to analyze the incidence of readmission at their center, to define causes of unplanned readmission, and to determine the preoperative and surgical variables associated with readmissions following pediatric neurosurgery. METHODS A total of 536 children who underwent operations for neurosurgical diagnoses between 2012 and 2015 and who were later readmitted were included in the final analysis. Unplanned readmissions were defined to have occurred as a result of complications within 90 days after index surgery. Patient records were retrospectively reviewed to determine the primary diagnosis, surgery indication, and cause of readmission and return to operating room. The cost for index hospitalization, readmission episode, and total cost were derived based on the charges obtained from administrative data. Bivariate and multivariable analyses were conducted. RESULTS Of 536 patients readmitted in total, 17.9% (n = 96) were readmitted within 90 days. Of the overall readmissions, 11.9% (n = 64) were readmitted within 30 days, and 5.97% (n = 32) were readmitted between 31 and 90 days. The median duration between discharge and readmission was 20 days (first quartile [Q1]: 9 days, third quartile [Q3]: 36 days). The most common reason for readmission was shunt related (8.2%, n = 44), followed by wound infection (4.7%, n = 25). In the risk-adjusted multivariable logistic regression model for total 90-day readmission, patients with the following characteristics: younger age (p = 0.001, OR 0.886, 95% CI 0.824-0.952); "other" (nonwhite, nonblack) race (p = 0.024, OR 5.49, 95% CI 1.246-24.2); and those born preterm (p = 0.032, OR 2.1, 95% CI 1.1-4.12) had higher odds of being readmitted within 90 days after discharge. The total median cost for patients undergoing surgery in this study cohort was $11,520 (Q1: $7103, Q3: $19,264). For the patients who were readmitted, the median cost for a readmission episode was $8981 (Q1: $5051, Q3: $18,713). CONCLUSIONS Unplanned 90-day readmissions in pediatric neurosurgery are primarily due to CSF-related complications. Patients with the following characteristics: young age at presentation; "other" race; and children born preterm have a higher likelihood of being readmitted within 90 days after surgery. The median cost was > $8000, which suggests that the readmission episode can be as expensive as the index hospitalization. Clearly, readmission reduction has the potential for significant cost savings in pediatric neurosurgery. Future efforts, such as targeted education related to complication signs, should be considered in the attempt to reduce unplanned events. Given the single-center, retrospective study design, the results of this study are primarily applicable to this population and cannot necessarily be generalized to other institutions without further study.

Validation of algorithms to determine incidence of Hirschsprung disease in Ontario, Canada: a population-based study using health administrative data

Objective

Incidence rates of Hirschsprung disease (HD) vary by geographical region, yet no recent population-based estimate exists for Canada. The objective of our study was to validate and use health administrative data from Ontario, Canada to describe trends in incidence of HD between 1991 and 2013.

Study design

To identify children with HD we tested algorithms consisting of a combination of diagnostic, procedural, and intervention codes against the reference standard of abstracted clinical charts from a tertiary pediatric hospital. The algorithm with the highest positive predictive value (PPV) that could maintain high sensitivity was applied to health administrative data from April 31, 1991 to March 31, 2014 (fiscal years 1991–2013) to determine annual incidence. Temporal trends were evaluated using Poisson regression, controlling for sex as a covariate.

Results

The selected algorithm was highly sensitive (93.5%) and specific (>99.9%) with excellent predictive abilities (PPV 89.6% and negative predictive value >99.9%). Using the algorithm, a total of 679 patients diagnosed with HD were identified in Ontario between 1991 and 2013. The overall incidence during this time was 2.05 per 10,000 live births (or 1 in 4,868 live births). The incidence did not change significantly over time (odds ratio 0.998, 95% confidence interval 0.983–1.013, p = 0.80).

Conclusion

Ontario health administrative data can be used to accurately identify cases of HD and describe trends in incidence. There has not been a significant change in HD incidence over time in Ontario between 1991 and 2013.

Bleeding-related hospital admissions and 30-day readmissions in patients with non-valvular atrial fibrillation treated with dabigatran versus warfarin

Essentials Bleeding is a common cause of hospital admission and readmission in oral anticoagulant users. Patients with dabigatran and warfarin were included to assess hospital admission risk. Dabigatran users had a higher risk of 30-day readmission with bleeding than warfarin users. Close monitoring following hospital discharge for dabigatran-related bleeding is warranted.

SUMMARY

Background Reducing 30-day hospital readmission is a policy priority worldwide. Warfarin-related bleeding is among the most common cause of hospital admissions as a result of adverse drug events. Compared with warfarin, dabigatran achieves a full anticoagulation effect more quickly following its initiation; hence it may lead to early-onset bleeds. Objectives To compare the incidence of bleeding-related hospital admissions and 30-day readmissions with dabigatran vs. warfarin in patients with non-valvular atrial fibrillation (NVAF). Methods This was a retrospective cohort study using a population-wide database managed by the Hong Kong Hospital Authority. Patients newly diagnosed with NVAF from 2010 through to 2014 and prescribed dabigatran or warfarin were 1:1 matched by propensity score. The incidence rate of hospital admission with bleeding (a composite of gastrointestinal bleeding, intracranial hemorrhage and bleeding at other sites) was assessed. Results Among the 51 946 patients with NVAF, 8309 users of dabigatran or warfarin were identified, with 5160 patients matched by propensity score. The incidence of first hospitalized bleeding did not differ significantly between groups (incidence rate ratio, 0.92; 95% confidence interval [CI], 0.66-1.28). Among patients who were continuously prescribed their initial anticoagulants upon discharge, dabigatran use was associated with a higher risk of 30-day readmission with bleeding over warfarin (adjusted hazard ratio, 2.87; 95%CI, 1.10-7.43). Conclusion When compared with warfarin, dabigatran was associated with a comparable incidence of first hospital admission but a higher risk of 30-day redmission with respect to bleeding. Close early monitoring of patients initiated on dabigatran following hospital discharge for bleeding is warranted.

The impact of curve severity on obstetric complications and regional anesthesia utilization in pregnant patients with adolescent idiopathic scoliosis: a preliminary analysis

OBJECTIVE

Adolescent idiopathic scoliosis (AIS), the most common type of scoliosis, often presents immediately prior to a woman’s childbearing years; however, research investigating the impact of AIS on women’s health, particularly pregnancy delivery outcomes, is sparse, with existing literature reporting mixed findings. Similarly limited are studies examining the change in scoliotic curve during or after pregnancy. Therefore, this study aims to determine 1) the impact of scoliotic curvature on obstetric complications (preterm births, induction of labor, and urgent/emergency caesarean section delivery), 2) regional anesthetic decision making and success during delivery for these patients, and 3) the effect of pregnancy on curve progression.

METHODS

Records of all pregnant patients diagnosed with AIS at the authors’ institution who delivered between January 2002 and September 2016 were retrospectively reviewed. Demographic information, pre- and postpartum radiographic Cobb angles, and clinical data for each pregnancy and delivery were recorded and analyzed. The Wilcoxon rank-sum test and the Wilcoxon signed-rank test were used for statistical analyses.

RESULTS

Fifty-nine patients (84 deliveries) were included; 14 patients had undergone prior posterior spinal fusion. The median age at AIS diagnosis was 15.2 years, and the median age at delivery was 21.8 years. Overall, the median major Cobb angle prior to the first pregnancy was 25° (IQR 15°–40°). Most births were by spontaneous vaginal delivery (n = 45; 54%); elective caesarean section was performed in 17 deliveries (20%). Obstetric complications included preterm birth (n = 18; 21.4%), induction of labor (n = 20; 23.8%), and urgent/emergency caesarean section (n = 12; 14.0%); none were associated with severity of scoliosis curve or prior spinal fusion. Attempts at spinal anesthesia were successful 99% of the time (70/71 deliveries), even among the patients who had undergone prior spinal fusion (n = 13). There were only 3 instances of provider refusal to administer spinal anesthesia. In the subset of 11 patients who underwent postpartum scoliosis radiography, there was no statistically significant change in curve magnitude either during or immediately after pregnancy.

CONCLUSIONS

The results of this study suggest that there was no effect of the severity of scoliosis on delivery complications or regional anesthetic decision making in pregnant patients with AIS. Moreover, scoliosis was not observed to progress significantly during or immediately after pregnancy. Larger prospective studies are needed to further investigate these outcomes, the findings of which can guide the prenatal education and counseling of pregnant patients with AIS.

GNE-781, A Highly Advanced Potent and Selective Bromodomain Inhibitor of Cyclic Adenosine Monophosphate Response Element Binding Protein, Binding Protein (CBP)

Inhibition of the bromodomain of the transcriptional regulator CBP/P300 is an especially interesting new therapeutic approach in oncology. We recently disclosed in vivo chemical tool 1 (GNE-272) for the bromodomain of CBP that was moderately potent and selective over BRD4(1). In pursuit of a more potent and selective CBP inhibitor, we used structure-based design. Constraining the aniline of 1 into a tetrahydroquinoline motif maintained potency and increased selectivity 2-fold. Structure-activity relationship studies coupled with further structure-based design targeting the LPF shelf, BC loop, and KAc regions allowed us to significantly increase potency and selectivity, resulting in the identification of non-CNS penetrant 19 (GNE-781, TR-FRET IC₅₀ = 0.94 nM, BRET IC₅₀ = 6.2 nM; BRD4(1) IC₅₀ = 5100 nΜ) that maintained good in vivo PK properties in multiple species. Compound 19 displays antitumor activity in an AML tumor model and was also shown to decrease Foxp3 transcript levels in a dose dependent manner.

Light rare earth element depletion during Deepwater Horizon blowout methanotrophy

Rare earth elements have generally not been thought to have a biological role. However, recent work has demonstrated that the light REEs (LREEs: La, Ce, Pr, and Nd) are essential for at least some methanotrophs, being co-factors in the XoxF type of methanol dehydrogenase (MDH). We show here that dissolved LREEs were significantly removed in a submerged plume of methane-rich water during the Deepwater Horizon (DWH) well blowout. Furthermore, incubation experiments conducted with naturally methane-enriched waters from hydrocarbon seeps in the vicinity of the DWH wellhead also showed LREE removal concurrent with methane consumption. Metagenomic sequencing of incubation samples revealed that LREE-containing MDHs were present. Our field and laboratory observations provide further insight into the biochemical pathways of methanotrophy during the DWH blowout. Additionally, our results are the first observations of direct biological alteration of REE distributions in oceanic systems. In view of the ubiquity of LREE-containing MDHs in oceanic systems, our results suggest that biological uptake of LREEs is an overlooked aspect of the oceanic geochemistry of this group of elements previously thought to be biologically inactive and an unresolved factor in the flux of methane, a potent greenhouse gas, from the ocean.

Improving medication safety and diabetes management in Hong Kong: a multidisciplinary approach

INTRODUCTION

Patients with diabetes often require complex medication regimens. The positive impact of pharmacists on improving diabetes management or its co-morbidities has been recognised worldwide. This study aimed to characterise drug-related problems among diabetic patients in Hong Kong and their clinical significance, and to explore the role of pharmacists in the multidisciplinary diabetes management team by evaluating the outcome of their clinical interventions.

METHODS

An observational study was conducted at the Diabetes Clinic of a public hospital in Hong Kong from October 2012 to March 2014. Following weekly screening, and prior to the doctor's consultation, selected high-risk patients were interviewed by a pharmacist for medication reconciliation and review. Drug-related problems were identified and documented by the pharmacist who presented clinical recommendations to doctors to optimise a patient's drug regimen and resolve or prevent potential drug-related problems.

RESULTS

A total of 522 patients were analysed and 417 drug-related problems were identified. The incidence of patients with drug-related problems was 62.8% with a mean of 0.9 (standard deviation, 0.6) drug-related problems per patient. The most common categories of drug-related problems were associated with dosing (43.9%), drug choice (17.3%), and non-allergic adverse reactions (15.6%). Drugs most frequently involved targeted the endocrine or cardiovascular system. The majority (71.9%) of drug-related problems were of moderate clinical significance and 28.1% were considered minor problems. Drug-related problems were totally solved (50.1%) and partially solved (11.0%) by doctors' acceptance of pharmacist recommendations, or received acknowledgement from doctors (5.5%).

CONCLUSIONS

Pharmacists, in collaboration with the multidisciplinary team, demonstrated a positive impact by identifying, resolving, and preventing drug-related problems in patients with diabetes. Further plans for sustaining pharmacy service in the Diabetes Clinic would enable further studies to explore the long-term impact of pharmacists in improving patients' clinical outcomes in diabetes management.

Independent Preoperative Predictors of Prolonged Length of Stay after Laparoscopic Appendectomy in Patients over 30 Years of Age: Experience from a Single Institution

Prompt discharge after laparoscopic appendectomy (LA) is a marker of quality of care, fiscally desirable and feasible in select patients. Patients over 30 comprise a more heterogeneous cohort known to experience worse outcomes after LA. We aimed to identify easily available preoperative risk factors portending a postoperative length of stay ≥2 days among patients above age 30. In this investigation, 296 included patients from a single institution who underwent LA for acute appendicitis from 2010 to 2014 were retrospectively reviewed for preoperative demographics, laboratory studies, comorbidities, presentation characteristics, radiographic finding, and other rationally selected factors for association with postoperative length of stay ≥2 days. Bivariate and multivariate analysis was conducted to determine independent risk factors, which were subsequently modeled via receiver-operating characteristic curve generation and Kaplan-Meier analysis. “Classic” presentation [odds ratio (OR) = 0.5, P = .02], elevated red cell distribution width (RDW; OR = 1.5/% increase, P = 0.004) as well as evidence of rupture on CT (OR = 6.9, P < 0.001) were independently associated with postoperative length of stay ≥ 2 days. Modeling length of stay using these factors generated an area under the curve of 0.713 ± 0.037. Kaplan-Meier analysis of “classic” presentation, elevated RDW, and evidence of rupture on CT through the fifth postoperative day generated log-rank P values of 0.02, 0.05, and ≤ 0.001, respectively. In summary, lack of “classic” presentation, elevated RDW, and CT evidence of rupture are novel risk factors for prolonged postoperative length of stay in LA patients over 30. These findings may help target patients most appropriate for prompt discharge.

Methylphenidate and the risk of psychotic disorders and hallucinations in children and adolescents in a large health system

Previous studies have suggested that risk of psychotic events may be increased in children exposed to methylphenidate (MPH). However, this risk has not been fully examined, and the possibility of confounding factors has not been excluded. Patients aged 6-19 years who received at least one MPH prescription were identified using Hong Kong population-based electronic medical records on the Clinical Data Analysis and Reporting System (2001-2014). Using the self-controlled case series design, relative incidence of psychotic events was calculated comparing periods when patients were exposed to MPH with non-exposed periods. Of 20,586 patients prescribed MPH, 103 had an incident psychotic event; 72 (69.9%) were male and 31 (30.1%) female. The mean age at commencement of observation was 6.95 years and the mean follow-up per participant was 10.16 years. On average, each participant was exposed to MPH for 2.17 years. The overall incidence of psychotic events during the MPH exposure period was 6.14 per 10,000 patient-years. No increased risk was found during MPH-exposed compared with non-exposed periods (incidence rate ratio (IRR) 1.02 (0.53-1.97)). However, an increased risk was found during the pre-exposure period (IRR 4.64 (2.17-9.92)). Results were consistent across all sensitivity analyses. This study does not support the hypothesis that MPH increases risk of incident psychotic events. It does indicate an increased risk of psychotic events before the first prescription of MPH, which may be because of an association between psychotic events and the behavioural and attentional symptoms that led to psychiatric assessment and initiation of MPH treatment.

Independent Preoperative Predictors of Prolonged Length of Stay after Laparoscopic Appendectomy in Patients Over 30 Years of Age: Experience from a Single Institution

Prompt discharge after laparoscopic appendectomy (LA) is a marker of quality of care, fiscally desirable and feasible in select patients. Patients over 30 comprise a more heterogeneous cohort known to experience worse outcomes after LA. We aimed to identify easily available preoperative risk factors portending a postoperative length of stay ≥2 days among patients above age 30. In this investigation, 296 included patients from a single institution who underwent LA for acute appendicitis from 2010 to 2014 were retrospectively reviewed for preoperative demographics, laboratory studies, comorbidities, presentation characteristics, radiographic finding, and other rationally selected factors for association with postoperative length of stay ≥2 days. Bivariate and multivariate analysis was conducted to determine independent risk factors, which were subsequently modeled via receiver-operating characteristic curve generation and Kaplan-Meier analysis. "Classic" presentation [odds ratio (OR) = 0.5, P = .02], elevated red cell distribution width (RDW; OR = 1.5/% increase, P = 0.004) as well as evidence of rupture on CT (OR = 6.9, P < 0.001) were independently associated with postoperative length of stay ≥ 2 days. Modeling length of stay using these factors generated an area under the curve of 0.713 ± 0.037. Kaplan-Meier analysis of "classic" presentation, elevated RDW, and evidence of rupture on CT through the fifth postoperative day generated log-rank P values of 0.02, 0.05, and ≤ 0.001, respectively. In summary, lack of "classic" presentation, elevated RDW, and CT evidence of rupture are novel risk factors for prolonged postoperative length of stay in LA patients over 30. These findings may help target patients most appropriate for prompt discharge.

Discovery of a Potent and Selective in Vivo Probe (GNE-272) for the Bromodomains of CBP/EP300

The single bromodomain of the closely related transcriptional regulators CBP/EP300 is a target of much recent interest in cancer and immune system regulation. A co-crystal structure of a ligand-efficient screening hit and the CBP bromodomain guided initial design targeting the LPF shelf, ZA loop, and acetylated lysine binding regions. Structure-activity relationship studies allowed us to identify a more potent analogue. Optimization of permeability and microsomal stability and subsequent improvement of mouse hepatocyte stability afforded 59 (GNE-272, TR-FRET IC₅₀ = 0.02 μM, BRET IC₅₀ = 0.41 μM, BRD4(1) IC₅₀ = 13 μM) that retained the best balance of cell potency, selectivity, and in vivo PK. Compound 59 showed a marked antiproliferative effect in hematologic cancer cell lines and modulates MYC expression in vivo that corresponds with antitumor activity in an AML tumor model.

Abstract 5000: Immunotherapy with anti-PSMA x anti-CD3 bispecific antibody stimulates potent killing of a human prostate cancer cell line and target-mediated T cell activation in monkeys: A potential therapy for prostate cancer

PSMA (Prostate-Specific Membrane Antigen) is a promising therapeutic target in prostate cancer. Exploiting the high and selective expression of PSMA in the prostate, capromab and J591 antibodies are used as imaging or therapeutic agents, and antibody-toxin conjugates such as MLN2704 are being developed. Such antibodies do not stimulate T cell-mediated killing of prostate cancer cells; however, promising clinical data with T cell-recruiting bispecific agents and chimeric antigen receptor (CAR) T cells have created new immunotherapy paradigms that may also have potential in prostate cancer.

We designed long-acting humanized bispecific antibodies that coengage PSMA+ cells and CD3+ T cells to stimulate redirected T cell-mediated cytotoxicity (RTCC) of prostate cancer cells. Unlike other bispecific formats, our antibodies possess an Fc domain and form stable heterodimers that are easily manufactured. Binding to Fcγ receptors was also abolished (reducing the potential for nonselective T cell activation), yet binding to human FcRn was preserved to maintain long serum half-life.

We screened several anti-PSMA x anti-CD3 bispecific antibodies in vitro, and selected XmAb14484 based on its potent (&lt; 1ng/ml) stimulation of human T cell killing of the LNCaP prostate tumor cell line. RTCC activity required PSMA binding, because a non-specific control (XENP13245, anti-RSV x anti-CD3) was inactive. XmAb14484 crossreacts with monkey but not mouse targets; therefore, we evaluated its effects in cynomolgus monkeys. Peripheral blood cells do not express PSMA, so we were unable to monitor target cell depletion. However, T cell engagement of target cells induces distinct effects on peripheral T cells, which can be used as surrogate markers for activity in the prostate. After treatment with 0.03 mg/kg XmAb14484, CD4+ and CD8+ T cells were rapidly activated (quantified by CD69 upregulation) and redistributed from the periphery. Serum cytokines including IL-6 and TNF were also strongly induced. T cell and cytokine responses returned to baseline within 2-3 days. In marked contrast, a 100-fold higher dose (3 mg/kg) of the anti-RSV x anti-CD3 control antibody induced minimal effects, demonstrating that PSMA+ target cells are required for T cell activation by XmAb14484.

In summary, the pharmacologic activities of XmAb14484 on human cells and in monkeys support its clinical assessment in prostate cancer. We also demonstrate that T cell effects readily measured in peripheral blood (T cell redistribution, activation and cytokine induction) are useful surrogate markers of target-specific engagement.

Citation Format: Seung Y. Chu, Erik W. K. Pong, Rumana Rashid, Hsing Chen, Emily W. Chan, Sheryl Phung, Nancy A. Endo, Maria C. Ardila, Christine Bonzon, Irene W. L. Leung, Umesh S. Muchhal, Gregory L. Moore, Matthew J. Bernett, John R. Desjarlais, David E. Szymkowski. Immunotherapy with anti-PSMA x anti-CD3 bispecific antibody stimulates potent killing of a human prostate cancer cell line and target-mediated T cell activation in monkeys: A potential therapy for prostate cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5000.

Systematic review with meta-analysis: the association between the use of calcium channel blockers and gastrointestinal bleeding

BACKGROUND

Due to their potential anti-platelet effect, it is suggested that calcium channel blockers (CCBs) are associated with gastrointestinal bleeding (GIB). However, results from previous studies are conflicting.

AIM

To conduct a systematic review and meta-analysis of randomised controlled trials (RCTs) and observational studies to clarify the association between CCBs and GIB.

METHODS

We conducted a systematic search of PubMed, EMBASE, Cochrane library and Trial Register databases up to January 2015. Studies that evaluated exposure to CCBs reporting GIB outcomes were included in the meta-analysis. The inverse variance method with random effects model was used to calculate the pooled estimates.

RESULTS

Seventeen studies (four RCTs, eleven case-control and two cohort studies) were included in the meta-analysis. The summary risk ratio (RR) for GIB was 1.17 (95% CI 1.01-1.36) for CCB users vs. non-users. Subgroup analysis showed that CCB use was associated with a moderately higher risk of lower GIB (RR = 1.83, 95% CI 1.17-2.84) but not upper GIB. However, data from four RCTs did not support association between CCBs and GIB (RR = 0.93, 95% CI 0.82-1.05). Subgroup analyses further showed that the increased risk of GIB among CCB users was only observed in studies that failed to adjust for prior history of GIB (RR = 1.67, 95% CI 1.34-2.08) or use of anti-ulcer drugs (RR = 1.40, 95% CI 1.19-1.65).

CONCLUSION

Our meta-analysis showed a marginal association between calcium channel blocker use and the risk of gastrointestinal bleeding. This association is of dubious clinical significance, as the effects of different comparators or adjustment for confounding factors render this association nonsignificant.

Efficacy and safety of lorcaserin in obese adults: a meta-analysis of 1-year randomized controlled trials (RCTs) and narrative review on short-term RCTs

Lorcaserin is a new anti-obesity drug recently approved by US Food and Drug Administration. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to evaluate the association of lorcaserin therapy with weight loss and adverse events in obese adults (18-65 years old). Weight loss of 3.23 kg (95% confidence interval [CI]: 2.70, 3.75) and body mass index reduction of 1.16 kg m⁻² (95% CI: 0.98, 1.34) was observed compared with placebo in RCTs of 1 year duration. The use of lorcaserin for 8 and 12 weeks reduced weight of 1.60 kg (95% CI: 0.34, 2.86) and 2.9 kg (95% CI: 2.2, 3.5), respectively. In comparison to placebo, lorcaserin decreased waist circumference, blood pressure, total cholesterol, low-density lipoprotein-cholesterol and triglycerides, however did not statistically affect heart rate or high-density lipoprotein-cholesterol. Headache, nausea and dizziness were found to be significantly higher in the patients receiving lorcaserin than patients receiving placebo, whereas diarrhoea is no more likely than in patients receiving placebo. In conclusion, lorcaserin achieves modest weight loss and appears to be well tolerated. Clinical and pharmacovigilance studies with longer study duration are needed to inform of the long-term efficacy and safety of lorcaserin.

Validity of EuroQOL-5D, time trade-off, and standard gamble for age-related macular degeneration in the Singapore population

BACKGROUND/AIMS

Utility values of age-related macular degeneration (AMD) in Asian patients are unknown. This study aims to assess utility values and construct validity of the EuroQOL-5D (EQ-5D), time trade-off (TTO), and standard gamble (SG) instruments in the Singapore multi-ethnic AMD population.

METHODS

Cross-sectional, two-centre, institution-based study. Visual acuity (VA), clinical AMD severity, and utility scores on the EQ-5D, TTO, and SG were obtained from 338 AMD patients. VA was analysed in terms of the better-seeing eye (BEVA), worse-seeing eye (WEVA), and weighted average of both eyes (WVA). We evaluated SG on the perfect health-death (SG(death)) and binocular perfect vision-binocular blindness (SG(blindness)) scales. Construct validity was determined by testing a priorihypotheses relating the EQ-5D, TTO, and SG utility scores to VA and clinical AMD severity.

RESULTS

The mean utilities on the EQ-5D, TTO, SG(death), and SG(blindness) were 0.89, 0.81, 0.86, and 0.90, respectively. EQ-5D scores correlated weakly with BEVA, WEVA, and WVA (Pearson's correlation coefficients -0.291, -0.247, and -0.305 respectively, P<0.001 for all). SG(death) and SG(blindness) demonstrated no correlation with BEVA, WEVA, or WVA (Pearson's correlation coefficients, range -0.06 to -0.125). TTO showed weak association only with WEVA and WVA (correlation coefficients -0.237, -0.228, P<0.0001), but not with BEVA (correlation coefficient -0.161). Clinical AMD severity correlated with EQ-5D and SG(death), but not with TTO and SG(blindness) (P=0.004, 0.002, 0.235, and 0.069, respectively).

CONCLUSIONS

AMD has a negative impact on utilities, although utility scores were high compared with Western cohorts. EQ-5D, TTO, and SG showed suboptimal construct validity, suggesting that health status utilities may not be sufficiently robust for cost-utility analyses in this population.

Multiple roles for the receptor tyrosine kinase axl in tumor formation

A focus of contemporary cancer therapeutic development is the targeting of both the transformed cell and the supporting cellular microenvironment. Cell migration is a fundamental cellular behavior required for the complex interplay between multiple cell types necessary for tumor development. We therefore developed a novel retroviral-based screening technology in primary human endothelial cells to discover genes that control cell migration. We identified the receptor tyrosine kinase Axl as a novel regulator of endothelial cell haptotactic migration towards the matrix factor vitronectin. Using small interfering RNA-mediated silencing and overexpression of wild-type or mutated receptor proteins, we show that Axl is a key regulator of multiple angiogenic behaviors including endothelial cell migration, proliferation, and tube formation in vitro. Moreover, using sustained, retrovirally delivered short hairpin RNA (shRNA) Axl knockdown, we show that Axl is necessary for in vivo angiogenesis in a mouse model. Furthermore, we show that Axl is also required for human breast carcinoma cells to form a tumor in vivo. These findings indicate that Axl regulates processes vital for both neovascularization and tumorigenesis. Disruption of Axl signaling using a small-molecule inhibitor will hence simultaneously affect both the tumor and stromal cell compartments and thus represents a unique approach for cancer therapeutic development.

Mutations in topoisomerase genes of fluoroquinolone-resistant salmonellae in Hong Kong

A total of 88 salmonella isolates (72 clinical isolates for which the ciprofloxacin MIC was >0.06 microg/ml, 15 isolates for which the ciprofloxacin MIC was < or =0.06 microg/ml, and Salmonella enterica serotype Typhimurium ATCC 13311) were studied for the presence of genetic alterations in four quinolone resistance genes, gyrA, gyrB, parC, and parE, by multiplex PCR amplimer conformation analysis. The genetic alterations were confirmed by direct nucleotide sequencing. A considerable number of strains had a mutation in parC, the first to be reported in salmonellae. Seven of the isolates sensitive to 0.06 micro g of ciprofloxacin per ml had a novel mutation at codon 57 of parC (Tyr57-->Ser) which was also found in 29 isolates for which ciprofloxacin MICs were >0.06 micro g/ml. Thirty-two isolates had a single gyrA mutation (Ser83-->Phe, Ser83-->Tyr, Asp87-->Asn, Asp87-->Tyr, or Asp87-->Gly), 34 had both a gyrA mutation and a parC mutation (29 isolates with a parC mutation of Tyr57-->Ser and 5 isolates with a parC mutation of Ser80-->Arg). Six isolates which were isolated recently (from 1998 to 2001) were resistant to 4 micro g of ciprofloxacin per ml. Two of these isolates had double gyrA mutations (Ser83-->Phe and Asp87-->Asn) and a parC mutation (Ser80-->Arg) (MICs, 8 to 32 microg/ml), and four of these isolates had double gyrA mutations (Ser83-->Phe and Asp87-->Gly), one parC mutation (Ser80-->Arg), and one parE mutation (Ser458-->Pro) (MICs, 16 to 64 micro g/ml). All six of these isolates and those with a Ser80-->Arg parC mutation were S. enterica serotype Typhimurium. One S. enterica serotype Typhi isolate harbored a single gyrA mutation (Ser83-->Phe), and an S. enterica serotype Paratyphi A isolate harbored a gyrA mutation (Ser83-->Tyr) and a parC mutation (Tyr57-->Ser); both of these isolates had decreased susceptibilities to the fluoroquinolones. The MICs of ciprofloxacin, levofloxacin, and sparfloxacin were in general the lowest of those of the six fluoroquinolones tested. Isolates with a single gyrA mutation were less resistant to fluoroquinolones than those with an additional parC mutation (Tyr57-->Ser or Ser80-->Arg), while those with double gyrA mutations were more resistant.

What have we learnt from community-acquired infections in Hong Kong?

This study was initiated throughout Hong Kong, to reveal the characteristics of community-acquired infections. All specimens collected by general practitioners from infected patients were followed prospectively, and those that were culture-positive were analysed. Four thousand seven hundred and forty-one specimens were collected from 3977 patients by 89 doctors from July 2000 to October 2001. The most common specimens were throat swabs (33%), urine (26%) and sputa (16%). The average culture-positive rate was 28%. The most common organisms were Escherichia coli (18%), beta-haemolytic streptococci (15%) and Staphylococcus aureus (12%). Fluoroquinolone resistance was relatively high (up to 35%) in organisms commonly causing urinary tract infection (E. coli, Proteus and Morganella). Although none of the pneumococci was resistant to penicillin 1 mg/L, the proportion with intermediate resistance (0.1-1 mg/L) was alarming (81%). There were three strains of methicillin-resistant S. aureus. A decrease in ampicillin resistance but a high prevalence of macrolide resistance were noted in Haemophilus influenzae. All Neisseria gonorrhoeae isolates were resistant to penicillin, up to 79% to the fluoroquinolones, 15% to spectinomycin, but all were susceptible to ceftriaxone. Respiratory pathogens (Streptococcus pneumoniae, beta-haemolytic streptococci and H. influenzae) were relatively susceptible to the newer fluoroquinolones (0-2%, 0.5-6% and 2% resistant, respectively) or third-generation cephalosporins (0-2% resistant). The distribution of organisms and their antibiotic resistance varied over time. Thus frequent surveillance is needed to provide information on the drugs of choice for different infections.

Triptolide induced cytotoxic effects on human promyelocytic leukemia, T cell lymphoma and human hepatocellular carcinoma cell lines

Triptolide, a traditional Chinese medicine, has been reported to be effective in the treatment of auto-immune diseases, and it can also induce anti-neoplastic activity on several human tumor cell lines. This study investigates the cytotoxic function and the functional mechanism of triptolide on tumor cells. Promyelocytic leukemia, (HL-60), T cell lymphoma (Jurkat), and human hepatocelluar carcinoma (SMMC-7721) cells were subjected to triptolide treatment, and cell growth inhibition was examined by XTT cell viability assay. Cell death mechanism (apoptosis) was confirmed through DNA fragmentation and DAPI staining. Triptolide inhibited 50% of cell growth (IC(50)) on HL-60 cells at 7.5 nM, Jurkat cells at 27.5 nM and SMMC cells at 32 nM. Characteristic apoptotic features including internucleosomal DNA fragmentation and chromatin condensation were observed in triptolide treated cells. Data from the study indicates that triptolide could induce apoptosis in human tumor cell lines and it may be applicable as a potential chemotherapeutic agent for cancer treatment.

Molecular epidemiological analysis of Salmonella enterica serotype Derby infections in Hong Kong

OBJECTIVES

We aimed to study the antimicrobial susceptibilities and molecular epidemiology of Salmonella enterica serotype Derby, a unique and common salmonella serotype in Hong Kong.

METHODS

Salmonella Derby strains isolated from stools of patients in a large general hospital in Hong Kong from 1989 to 1994 and from food samples isolated in the Public Health Laboratory were randomly selected and investigated for the antimicrobial susceptibilities by determining the minimal inhibitory concentrations of 19 antimicrobial agents and their relatedness using plasmid analysis, ribotyping, pulsed-field gel electrophoresis (PFGE) and total DNA fingerprinting.

RESULTS

About 50% of the 127 isolates studied were susceptible to all the 19 antibiotics tested, although resistance to tetracycline (49%) and sulfamethoxazole (38%) was high. Only 12% did not harbour any detectable plasmids, while the rest contained plasmids in 51 profiles. There were two predominant clones, one comprising of 35% of isolates that could not be pulsotyped because discrete bands were not discernible after PFGE and another comprising 34% of isolates that could be pulsotyped. The remaining 31% belonged to a variety of types.

CONCLUSIONS

Approximately 70% of S. Derby belonging to two clones were endemic in the community, while the remaining isolates belonged to a variety of types which were probably a result of sporadic infection. The sources of human infections were foods, since most isolates from foods also belonged to the two endemic clones. Typing of S. Derby isolates from other sources such as animals or the environment would help elucidate how foods were contaminated. PFGE might not be universally applicable to all salmonella strains.

Plasmids encoding foot-and-mouth disease virus VP1 epitopes elicited immune responses in mice and swine and protected swine against viral infection

VP1 is a capsid protein of foot-and-mouth disease virus (FMDV) and contains epitopes of the virus. Plasmids encoding two VP1 epitopes (amino acid residues 141-160 and 200-213) and a host-self immunoglobulin molecule were constructed to produce a new type of FMD DNA vaccine. Two plasmids, namely, pCEIM and pCEIS, containing mouse immunoglobulin (IgG) or swine IgG were subjected to immunogenicity testing in mice and swine, respectively. In mice administrated pCEIM in the abdomen using a genegun, both FMDV-specific T-cell proliferation and neutralizing antibodies were detected. In swine immunized with pCEIS at the back of the ear, immune responses were achieved after the second administration. Swine showed a T-cell proliferative response with a stimulation index (SI) of up to 8.1 and a neutralizing antibody response that was able to protect suckling mice from 10(2) LD(50) (lethal dose 50) FMDV challenge. To compare the immunogenicity of the DNA-based vaccine candidate, versus the protein-based vaccine candidates, a second group of swine was immunized with the protein F1-scIgG, which was encoded by the plasmid pCEIS. Injection with F1-scIgG elicited a T-cell proliferative response of SI < 1.7 and a neutralizing antibody response that protected suckling mice from up to 10(5) LD(50) FMDV challenge. In the challenge test, three of three swine immunized with pCEIS were fully protected from FMDV challenge.

An immunoglobulin G based chimeric protein induced foot-and-mouth disease specific immune response in swine

Epitopes containing the residues 141aa-160aa and 200aa-213aa from foot-and-mouth disease (FMD) serotype O1K HK type FMDV VP1 were joined to a swine immunoglobulin G single heavy chain constant region (scIgG), creating a novel chimeric protein, named F1-scIgG. In this study, inoculation with F1-scIgG induced both FMD virus-neutralizing antibody response and T cell response in swine. Antisera from these F1-scIgG-inoculated swine protected suckling mice against 1000 lethal dose 50 (1000LD(50)) FMD challenge. F1-scIgG-inoculated swine were also fully protected against 50LD(50) FMD virus challenge. The present study demonstrates the clear potential for viral epitopes linked with self-Ig in novel FMD vaccine design.

Stability of cefazolin sodium eye drops

OBJECTIVE

Assessing the stability of cefazolin sodium in preservative-free and preservative-containing eye drops.

METHOD

Extemporaneous formulations of eye drops were prepared from a commercially-available parenteral product of cefazolin sodium: eye drops 'A' contained 50mg/ml of cefazolin sodium in 0.45% w/v sodium chloride solution, and eye drops 'B' contained 50 mg/ml, 0.005% w/v thiomersal and 1% w/v glycerol in water-for-injection. Cefazolin sodium concentrations in these eye drops were monitored by a stability-indicating HPLC assay method. Measurements of pH and osmolality, as well as tests for microbial contamination, were conducted.

RESULTS

The eye drops stored at 4 degrees C were stable for 42 days with minimal changes in pH and osmolality, but eye drops stored at room temperature were only stable for a few days with greater increments in pH and osmolality. None of the samples cultured had bacterial or fungal growth after 7 days of incubation.

CONCLUSION

Extemporaneously prepared formulations of cefazolin are unstable at room temperature and should be stored in a refrigerator.

Stability of phenoxybenzamine hydrochloride in various vehicles

The stability of phenoxybenzamine hydrochloride in various oral liquids was studied. Phenoxybenzamine hydrochloride powder or capsules were combined with various vehicles to prepare 10-mL formulations with a drug concentration of 2 mg/mL and a 20-mL stock solution containing 10 mg/mL. All formulations were prepared in triplicate and stored at 4 degrees C. A 1.0-mL sample of each of the 2-mg/mL formulations was withdrawn on days 0, 1, 2, 3, and 4, and samples of selected formulations were taken on days 7 and 10. Samples of the stock solution were withdrawn on days 0, 2, 4, 7, 10, 14, and 30. All samples were analyzed by high-performance liquid chromatography. Phenoxybenzamine hydrochloride 2 mg/mL was stable for a longer time in 1% propylene glycol, 0.15% citric acid, and water than in a similar vehicle in which syrup was used in place of water. The concentrations of the drug in both the 10-mg/mL stock solution and stock solutions diluted to 2 mg/mL were > 90% of the initial drug concentration for 30 days. Phenoxybenzamine hydrochloride 2 mg/mL in 1% propylene glycol and 0.15% citric acid in distilled water was stable for 7 days at 4 degrees C. A stock solution of phenoxybenzamine hydrochloride 10 mg/mL in propylene glycol was stable for 30 days at 4 degrees C and, after dilution with 66.7% sucrose in distilled water to a concentration of 2 mg/mL, for up to one hour at 4 degrees C.

Antiviral properties of polyinosinic acids containing thio and methyl substitutions

Polyinosinic acids containing methyl and sulphur substitutions are potent inhibitors of reverse transcriptase. Substitution of sulphur for oxygen at the 6 position produces significant effects on the properties of polyinosinic acid: the kinetics of inhibition change from competitive to mixed-type and the inhibition constant falls by three orders of magnitude. In contrast, 1-methyl substitution produces no such effects. Poly(1-methyl-6-thioinosinic acid) or poly(m1s6I) inhibits irreversibly, inhibiting all ten reverse transcriptases tested under a variety of assay conditions. In cell culture test systems, poly(m1s6I) is capable of blocking both infection by non-transforming viruses and transformation by a sarcoma virus. The presence of poly(m1s6I) in a preinfected culture results in the production of non-infectious virus particles lacking reverse transcriptase activity.

Effects of polyethylene glycol on reverse transcriptase and other polymerase activities

Polyethylene glycol enhances reverse transcription, augmenting both the rate and duration of polymerization. The effective mean molecular weight of polyethylene glycol is 6000 and the optimal concentration is 12% (w/w). Polyethylene glycol is effective on the reverse transcriptase reaction of all ten type B, C, and D viruses tested under a variety of exogenous, endogenous, and reconstitution assay systems, including the highly efficient conditions involving calf thymus DNA oligonucleotide primers. By three methods of synthesis, polyethylene glycol increased the yields of complementary [3H]DNA by a factor of 1.8--6.5. Polyethylene glycol does not alter the divalent cation requirements of the specificities of the enzyme. Complementary [3H]DNAs made in the presence of polyethylene glycol are indistinguishable in terms of size and sequence complementarity from those made in the absence of the polymer. The stimulatory effect was partly due to the ability of polyethylene glycol to stabilize reverse transcriptase. Preliminary tests indicate that polyethylene glycol also stimulates other nucleotide polymerases, such as the DNA-dependent DNA and RNA polymerases of Escherichia coli and the terminal transferase of calf thymus.

Microtissue culture plaque assay for Herpesvirus saimiri

A microtissue culture method for the plaque assay of Herpesvirus saimiri has been developed. Virus titrations carried out in Microtest II tissue culture plates (Falcon) yielded reproducible results that agreed well with those obtained by employing macrocultures. The described method is quantitative, reproducible, economical, and suitable for routine assay of large numbers of virus samples.