Success of Liquid Tumor Biopsy in Men with Metastatic Prostate Cancer According to Self-Identified Race

PURPOSE/OBJECTIVE(S)

Liquid biopsy using cell-free DNA (cfDNA) is increasingly used to identify somatic prostate cancer (PrCa) alterations when tissue biopsy of a metastatic lesion is infeasible or impractical. High-risk somatic alterations identified by cfDNA have been recently shown to predict the benefit of metastasis-directed therapy with stereotactic body radiation therapy in PrCa. However, given the older age of PrCa patients, liquid biopsy is often contaminated with alterations related to clonal hematopoiesis of indeterminate potential (CHIP), generating uncertainty in the clinical utility of the results. Given the higher incidence and aggressiveness of metastatic PrCa in Black men, we sought to determine if the success of cfDNA testing varied by race in a large and diverse cohort of United States Veterans with metastatic PrCa, hypothesizing that race would not influence the success of cfDNA testing.

MATERIALS/METHODS

Veterans with metastatic PrCa underwent next-generation sequencing of cfDNA biopsy specimens through the VA National Precision Oncology Program from February 2019 to November 2022. Successful identification of PrCa with cfDNA testing was defined as the identification of an alteration in one or more PrCa-related related genes in the gene panel tested (AR, CDK12, SPOP, MED12, CCND1, BRAF, AKT1, TMPRSS2, ERG, ETV1, and ETV4). Univariate logistic regression was employed to explore the association between patient self-identified race, as well as other patient and disease-specific factors at the time of cfDNA biopsy, with the likelihood of yielding a successful cfDNA biopsy result.

RESULTS

A total of 2066 cfDNA tests from 1985 Veterans were related to a diagnosis of PrCa, passed quality control measures, and were linkable to patient-level demographics. Median age at testing was 74, median PSA at testing was 22.7, median PSA doubling time (PSADT) was 3.6 months, and median Gleason score was 8. 57% of Veterans self-identified as White, 33% as Black, and 10% as Other. Eight hundred fourteen (39%) tests were deemed successful by finding a PrCa related gene alteration. Among successful tests, the most frequently encountered alterations were AR alterations in 60.4% White men and 33.9% Black men (p = 0.72), followed by TMPRSS2 alterations in 70.3% White men and 22.0% Black men (p<0.001). Despite a lower rate of PrCa-specific alterations in Black men, on univariate analysis, Veteran self-identified race was not associated with successful cfDNA testing (OR 0.95, 95% CI 0.78-1.14, p = 0.6), whereas PSA in quintiles 2-4, PSADT <12 months, and unit increase in Gleason score were associated with successful cfDNA testing (p<0.01 for all).

CONCLUSION

Successful cfDNA biopsy in metastatic PrCa is associated with PSA and PSADT, but not related to patient self-identified race. In appropriate clinical scenarios, patients who self-identify as Black or White are equally likely to have PrCa-specific alterations detected on cfDNA testing when evaluating metastatic PrCa patients for local and systemic therapies.

Assessing COVID-19 testing strategies in K-12 schools in underserved populations: study protocol for a cluster-randomized trial

Background

Since March 2020, COVID-19 has disproportionately impacted communities of color within the United States. As schools have shifted from virtual to in-person learning, continual guidance is necessary to understand appropriate interventions to prevent SARS-CoV-2 transmission. Weekly testing of students and staff for SARS-CoV-2 within K-12 school setting could provide an additional barrier to school-based transmission, especially within schools unable to implement additional mitigation strategies and/or are in areas of high transmission. This study seeks to understand the role that weekly SARS-CoV-2 testing could play in K-12 schools. In addition, through qualitative interviews and listening sessions, this research hopes to understand community concerns and barriers regarding COVID-19 testing, COVID-19 vaccine, and return to school during the COVID-19 pandemic.

Methods/design

Sixteen middle and high schools from five school districts have been randomized into one of the following categories: (1) Weekly screening + symptomatic testing or (2) Symptomatic testing only. The primary outcome for this study will be the average of the secondary attack rate of school-based transmission per case. School-based transmission will also be assessed through qualitative contact interviews with positive contacts identified by the school contact tracers. Lastly, new total numbers of weekly cases and contacts within a school-based quarantine will provide guidance on transmission rates. Qualitative focus groups and interviews have been conducted to provide additional understanding to the acceptance of the intervention and barriers faced by the community regarding SARS-CoV-2 testing and vaccination.

Discussion

This study will provide greater understanding of the benefit that weekly screening testing can provide in reducing SARS-CoV-2 transmission within K-12 schools. Close collaboration with community partners and school districts will be necessary for the success of this and similar studies.

Trial Registration

NCT04875520. Registered May 6, 2021.

The effects and effectiveness of electromotive drug administration and chemohyperthermia for treating non-muscle invasive bladder cancer

INTRODUCTION

Preliminary studies show that device assisted intravesical therapies appear more effective than passive diffusion intravesical therapy for the treatment of non-muscle invasive bladder cancer (NMIBC) in specific settings, and phase III studies are now being conducted. Consequently, we have undertaken a non-systematic review with the objective of describing the scientific basis and mechanisms of action of electromotive drug administration (EMDA) and chemohyperthermia (CHT).

METHODS

PubMed, ClinicalTrials.gov and the Cochrane Library were searched to source evidence for this non-systematic review. Randomised controlled trials, systematic reviews and meta-analyses were evaluated. Publications regarding the scientific basis and mechanisms of action of EMDA and CHT were identified, as well as clinical studies to date.

RESULTS

EMDA takes advantage of three phenomena: iontophoresis, electro-osmosis and electroporation. It has been found to reduce recurrence rates in NMIBC patients and has been proposed as an addition or alternative to bacillus Calmette-Guérin (BCG) therapy in the treatment of high risk NMIBC. CHT improves the efficacy of mitomycin C by three mechanisms: tumour cell cytotoxicity, altered tumour blood flow and localised immune responses. Fewer studies have been conducted with CHT than with EMDA but they have demonstrated utility for increasing disease-free survival, especially in patients who have previously failed BCG therapy.

CONCLUSIONS

It is anticipated that EMDA and CHT will play important roles in the management of NMIBC in the future. Techniques of delivery should be standardised, and there is a need for more randomised controlled trials to evaluate the benefits of the treatments alongside quality of life and cost-effectiveness.

Imaging, procedural and clinical variables associated with tumor yield on bone biopsy in metastatic castration-resistant prostate cancer

BACKGROUND

Understanding the mechanisms driving disease progression is fundamental to identifying new therapeutic targets for the treatment of men with metastatic castration-resistant prostate cancer (mCRPC). Owing to the prevalence of bone metastases in mCRPC, obtaining sufficient tumor tissue for analysis has historically been a challenge. In this exploratory analysis, we evaluated imaging, procedural and clinical variables associated with tumor yield on image-guided bone biopsy in men with mCRPC.

METHODS

Clinical data were collected prospectively from men with mCRPC enrolled on a phase II trial with serial metastasis biopsies performed according to standard clinical protocol. Imaging was retrospectively reviewed. We evaluated the percent positive biopsy cores (PPC), calculated as the number of positive cores divided by the total number of cores collected per biopsy.

RESULTS

Twenty-nine men had 39 bone biopsies. Seventy-seven percent of bone biopsies had at least one positive biopsy core. We determined that lesion size and distance from the skin to the lesion edge correlated with tumor yield on biopsy (median PPC 75% versus 42% for lesions >8.8 cm(3) versus ⩽ 8.8 cm(3), respectively, P=0.05; median PPC 33% versus 71% for distance ⩾ 6.1 versus <6.1 cm, respectively, P = 0.02). There was a trend towards increased tumor yield in patients with increased uptake on radionuclide bone scan, higher calcium levels and shorter duration of osteoclast-targeting therapy, although this was not statistically significant. Ten men had 14 soft tissue biopsies. All soft tissue biopsies had at least one positive biopsy core.

CONCLUSIONS

This exploratory analysis suggests that there are imaging, procedural and clinical variables that have an impact on image-guided bone biopsy yield. In order to maximize harvest of prostate cancer tissue, we have incorporated a prospective analysis of the metrics described here as part of a multi-institutional project aiming to use the molecular characterization of mCRPC tumors to direct individual therapy.

GDF15 is a potential predictive biomarker for TPF induction chemotherapy and promotes tumorigenesis and progression in oral squamous cell carcinoma

BACKGROUND

Randomized trials have not shown major survival benefits when induction chemotherapy plus standard therapy is compared with standard therapy alone in patients with oral squamous cell carcinoma (OSCC). Induction chemotherapy is likely to be effective for biologically distinct subgroups and biomarker development may lead to identification of patients whose tumors are likely to respond to a particular treatment.

PATIENTS AND METHODS

We evaluated immunohistochemical staining for GDF15 in pretreatment biopsy specimens of 230 of 256 OSCC patients who were treated in a prospective, randomized, phase III trial on induction chemotherapy including docetaxel, cisplatin and 5-fluorouracil (TPF). Relationship between GDF15 intervention and cell proliferation, migration, invasion, colony formation and tumorigenicity was analyzed using in vitro and in vivo OSCC models.

RESULTS

Low GDF15 expression predicted a better survival in OSCC patients, especially overall survival [P = 0.049, hazard ratio (HR) = 0.597] and distant metastasis-free survival (DMFS; P = 0.031, HR = 0.562). cN+ patients with low GDF15 expression benefitted from induction TPF in overall survival (P = 0.039, HR = 0.247) and DMFS (P = 0.039, HR = 0.247), cN- patients with high GDF15 expression benefitted from induction TPF in overall survival (P = 0.019, HR = 0.231), disease-free survival (P = 0.011, HR = 0.281), locoregional recurrence-free survival (P = 0.035, HR = 0.347) and DMFS (P = 0.009, HR = 0.197). Decreased GDF15 expression in OSCC lines significantly inhibited cell proliferation, migration, invasion, colony formation and tumorigenesis through increased phosphorylation of AKT and ERK1/2 (P < 0.05). Likewise, overexpression of GDF15 significantly promoted cell proliferation, migration, invasion and colony formation through decreased phosphorylation of AKT and ERK1/2 (P < 0.05).

CONCLUSIONS

GDF15 expression can be used as a prognostic biomarker for OSCC, and as a predictive biomarker for benefitting from TPF induction chemotherapy. GDF15 promotes tumorigenesis and progression through phosphorylation of AKT and ERK1/2 in OSCC. The clinical trial in this study was registered with www.ClinicalTrials.gov (NCT01542931).

Evaluation of the upper urinary tract using transureteric ultrasound--a review of the technique and typical imaging appearances

Ureteric strictures and pelviureteric junction obstruction often present a diagnostic conundrum to radiologists, particularly after the first-line investigations have failed to provide a definitive answer. Transureteric ultrasonography (TUU) is a relatively novel technique performed by the radiologist, which uses a miniature endoluminal ultrasound probe to interrogate the ureteric anatomy and peri-ureteric soft tissues. In this review, we discuss how TUU is performed, and the normal imaging appearances of the ureter and surrounding anatomical structures. We also focus on the various pathological processes that can be accurately evaluated or diagnosed using TUU including lymphadenopathy, calculi, ureteric neoplasms, ureteritis, crossing vessels and aneurysms. As TUU is not well established in UK practice as yet, we suggest possible indications for its use in the diagnostic work-up of urological patients and future applications.

Within-subject variability of measures of beta cell function derived from a 2 h OGTT: implications for research studies

AIMS/HYPOTHESIS

Knowledge of the within-subject variability of a parameter is required to properly design and calculate sample sizes for longitudinal studies. We sought to determine the day-to-day variability of measures of beta cell function derived from an OGTT.

METHODS

Thirty-seven adults (13 with normal glucose tolerance, ten with impaired glucose tolerance, 14 with type 2 diabetes) underwent a standard 2 h 75 g OGTT on two separate days (median time between tests, 7 days; range, 5-14). From these data, the reproducibility of several indices of beta cell function were determined: insulinogenic index (DeltaI(0-30)/DeltaG(0-30)), early C-peptide response (DeltaCP(0-30)/DeltaG(0-30)), incremental AUC insulin to glucose response (incAUC(ins)/incAUC(glu)), integrated insulin secretion response from 0 to 120 min (IS/Glu(0-120)) and indices of beta cell function derived from a mathematical model.

RESULTS

Within-subject variability for DeltaI(0-30)/DeltaG(0-30) (CV 57.1%) was higher than DeltaCP(0-30)/DeltaG(0-30) (CV 34.7%). Measures integrated over the full 120 min of the OGTT, incAUC(ins)/incAUC(glu) (CV 24.9%) and IS/Glu(0-120) (CV 17.4%), demonstrated less variability. The mathematical model-derived measures of beta cell glucose sensitivity (CV 20.3%) and potentiation (CV 33.0%) showed moderate variability. The impact of the different measures' variability on sample size (30% change from baseline) is demonstrated by calculated sample sizes of 89 for DeltaI(0-30)/DeltaG(0-30), 37 for DeltaCP(0-30)/DeltaG(0-30), 21 for incAUC(ins)/incAUC(glu) and 11 for IS/Glu(0-120).

CONCLUSIONS/INTERPRETATION

Some OGTT-derived indices of beta cell function, in particular the insulinogenic index, demonstrate high within-subject variability. Integrated measures that utilise multiple time points and measures that use C-peptide show less variability and may lead to a reduced sample size requirement.

Multi-center study evaluating circulating tumor cells (CTCs) as a surrogate for survival in men treated for castration refractory prostate cancer (CRPC)

5016

Background: Monitoring CTCs in patients undergoing therapy for metastatic breast cancer is an effective means to predict outcome and monitor treatment. The primary endpoint of this prospective multi-center study was to demonstrate a significant relation between the presence of CTCs and survival in men treated for CRPC. Methods: 276 patients with diagnosed CRPC, PSA progression, and an ECOG score of 0–2 about to begin initial or salvage chemo and/or combination therapy were enrolled. CTCs were enumerated with the CellSearch System in blood drawn pre-treatment and monthly thereafter for up to 18 months. Patient data were collected and maintained by an independent CRO. Median overall survival (OS) was determined for patients with =5 CTC /7.5mL at baseline and specified intervals. Results: Of 240 evaluable patients, 142 (59%) are alive - mean follow-up 11.4 ± 4.4 months. Median OS (in months) and significance between the two groups (logrank p-value) at different time points after the initiation of therapy are indicated in the table . Median OS for 40 (19%) patients with a reduction of CTCs below 5 CTCs 2–5 weeks after initiation of therapy was significantly longer as compared to those 78 (38%) patients that remained above 5 CTCs (>20 vs. 9.3mth, p=0.0000) and was not significantly different from the 83 (40%) patients with 20 vs. >20mth, p=0.2725). In multivariate analyses, which included stage at diagnosis, age, ECOG, Gleason score, LDH, Alkaline Phosphotase, and PSA, CTCs remained the most significant independent predictor of outcome. Conclusions: CTC levels in CRPC patients are a strong predictor of OS. The persistence of CTCs after initiation of therapy suggests that the patients are deriving less than optimal benefit from their current therapy. CTC levels may be a valid surrogate end-point in monitoring response to chemotherapy.

[Table: see text]

No significant financial relationships to disclose.

A new mechanism of estrogen action in prostate cancer: Inhibition of tissue androgen production and prostate cancer growth by Estradiol in androgen independent prostate cancer xenografts

15509

Background: Estrogens are effective agents in treating prostate cancer in patients in which serum androgens are already at ‘castrate‘ or anorchid levels. The mechanisms whereby estrogens inhibit ‘androgen-independent‘ prostate cancer are unclear. Methods: The androgen-independent human prostate cancer xenograft LuCaP 35V was implanted into orchiectomized male SCID mice and established tumors were treated with placebo pellets, 17β-estradiol (E2) slow-release pellets or E2 with the estrogen receptor antagonist ICI 182,780 as previously described (Clin Cancer Res 8:1003). Effects of E2 on tumor growth and tissue testosterone (T) and dihydrotestosterone (DHT) levels were evaluated by radioimmunoassay. Results: E2 significantly inhibited growth of androgen-independent LuCaP35V ( ∼35% inhibition at 4 weeks, p=0.0047, and increased survival of tumor bearing animals, (p trend =0.03) . The estrogen receptor antagonist ICI 182,780 did not block E2 inhibition of tumor growth, suggesting a receptor independent mechanism of tumor suppression. We then examined the effect of E2 on tissue T and DHT. E2 suppressed levels of tumor T and DHT in treated tumors. Tissue androgens in placebo treated LuCaP35V xenografts were; T=1.21 (± 0.18) pg/mg and DHT=3.54 (±1.07) pg/mg, and in E2-treated LuCaP35V T=0.23 (±0.09) pg/mg and DHT =0.44 (±0.14) pg/mg, (p<0.001). Levels of T and DHT in control liver tissue from both placebo and E2-treated animals were equivalent, at less than 0.2 pg/mg. Conclusions: We have shown that E2 inhibits growth of the androgen- independent human prostate cancer xenograft LuCaP35V, and that this inhibition is estrogen receptor independent. E2 significantly suppressed tumor tissue T and DHT suggesting a new mechanism of E2 mediated growth inhibition of androgen independent prostate cancer, potentially through inhibition of tumoral steroidogenesis. This model of ‘intracrine‘ tumor androgen production can be used to evaluate other inhibitors of tissue steroidogenesis.

No significant financial relationships to disclose.

Diethylstilbestrol and docetaxel: A phase II study in patients with metastatic, androgen independent prostate cancer

4627

Background: The combination of diethylstilbestrol (DES) and docetaxel has additive to synergistic activity against prostate cancer in preclinical models and DES inhibits expression of taxane resistant tubulin isoforms. The objective of this study is to determine the effects of the combination of DES and docetaxel on PSA, overall response, and toxicity. Methods: Twenty nine patients with metastatic androgen independent prostate cancer progressing by rising PSA or scan were treated with DES 5 mg daily the day prior to docetaxel and 1 mg daily continuously in combination with Docetaxel 36mg/m2 IV weekly for 3 weeks of a 4 week cycle. Prophylactic anticoagulation was used in all patients. All patients were assessed by PSA monthly and CT or bone scans every 3 cycles. Dose modifications for hematologic, hepatic and renal toxicity were made. The RECIST criteria and PSA decline by >50% which was maintained for 4 weeks were used. Results: The median age is 69 years (56–84), SWOG PS 0 (0–1), alkaline phosphatase 120 U/L (45–523), Hgb 12.6 g/dL (9.2–16.3), PSA 67 ng/dL (6–1962). The median number of cycles is 5. The median follow up after completion of therapy is 6 mos (1–18). Soft tissue metastases were present in 46% of patients and bone metastases in 96%. Twenty four patients are evaluable for response and toxicity. Of these, 18 patients (75%) had PSA responses and the PSA declined by >90% in 9 patients (38%). The overall response for was 75%. 11 patients suffered grade 3/4 toxicity. Two patients died of causes unrelated to therapy and another died from a steroid induced ulcer. The median number of cycles for responding patients is 9. Two patients developed thrombosis and were positive for Factor V mutations. Conclusions: The combination of DES and docetaxel is well tolerated and toxicity is indistinguishable from docetaxel alone. The overall response rate was 75%, with approximately half of responding patients achieving a PSA < 4.0, suggesting that DES improves the therapeutic index of docetaxel substantially and is an effective regimen using easily administered drugs. (Supported by Sanofi Aventis).

[Table: see text]

Outcome analysis and patient satisfaction following octant transrectal ultrasound-guided prostate biopsy: a prospective study comparing consultant urologist, specialist registrar and nurse practitioner in urology

PURPOSE

To determine whether transrectal ultrasound-guided biopsy of the prostate is equally reliable and acceptable if performed by urology nurse practitioner or urologist.

SCOPE

Octant biopsies were taken by each operator (consultant urologist n=2, urology specialist registrar n=1 and urology nurse practitioner n=2) from 50 consecutive unselected patients and demographics and cancer detection rate were compared between the groups. A postal survey was performed following nurse practitioner biopsy to assess patient satisfaction and acceptance of nurse practitioner biopsy.

CONCLUSION

Transrectal ultrasound-biopsy of prostate whether performed by nurse practitioner or urologist is equally reliable if adequate training is provided. Patients are happy to undergo prostate biopsy and receive information about the diagnosis from an appropriately trained prostate cancer nurse specialist.

Collection of wind-borne haematophagous insects in the Torres Strait, Australia

Circumstantial evidence has implicated wind-borne mosquitoes (Diptera: Culicidae) in the introduction of Japanese encephalitis (JE) virus into Australia from the New Guinea mainland. A study was initiated on Saibai Island in the northern Torres Strait, during January and February 2000, to identify the potential source of insects collected in aerial (kytoon) and surface-level traps. Wind speed and direction were recorded to determine wind profiles during insect sampling. Northerly winds capable of carrying insects from New Guinea to Saibai Island were only present on three out of 18 nights sampled. Only three male mosquitoes, comprising two Verrallina funerea (Theobald) and one Ochlerotatus vigilax (Skuse), were collected in aerial samples, and were most likely of local origin. Culicoides midges were also collected in aerial nets and included gravid/parous C. bundyensis Lee and Reye, and one parous C. histrio Johannsen. Highest densities of arthropods (up to 1562/million m3) were on 30 January 2000 when NW winds, sustained for six hours, probably introduced midges from the New Guinea mainland. Adult mosquitoes (including three female Ve. funerea and a single female Ficalbia) and Culicoides (including two gravid C. bundyensis and one parous C. cordiger Macfie) were also collected in 2 m high mast nets during northerly surface winds. Although the results do not provide evidence that wind-blown mosquitoes introduced JE from New Guinea into Australia, they do not preclude that strong N winds associated with low pressure systems SW of the Torres Strait could have done so. However, results suggest that Culicoides were more likely than mosquitoes to reach high altitude and travel long distances during the light N winds experienced during the study.

Validation of a flexible cystoscopy course

OBJECTIVE

To examine the instructional effectiveness of a course for nurses wishing to learn flexible cystoscopy, using a virtual reality flexible cystoscopy simulator to measure the outcome.

SUBJECTS AND METHODS

Fourteen urology nurse practitioners with no previous experience of cystoscopy were taught the basic techniques of flexible cystoscopy. They then had supervised group instruction during which they practised flexible cystoscopy on an inanimate latex model, and were taught how to handle the cystoscope, followed by unsupervised practice, including use of the virtual reality (VR) simulator (URO Mentor, Simbionix, Israel). They then undertook a cystoscopy task on the simulator; within the bladder there were 10 flags (numbered 1-10) at key positions. By visualizing and photographing each of the flags the subject would have visualized the entire bladder mucosa. The number of flags seen was thus used as a measure of how much of the bladder mucosa was examined. The VR simulator also measured the total procedure time. After a day of training the subjects were reassessed and the changes in performance evaluated. Subjects were also asked their opinion of the use of VR for flexible cystoscopy.

RESULTS

The median (range) time to complete the procedure before the course was 3.33 (2-5.5) min and the number of flags seen 7 (6-9). After the course, the median time decreased to 2.85 (1.5-4.42) min and the number of flags seen increased to 8 (6-9). The change in time was significant (P = 0.03) but the difference in the number of flags was not (P = 0.12). All 14 subjects enjoyed the use of VR for learning flexible cystoscopy; they all reported that they were more confident in handling a flexible cystoscope and in undertaking flexible cystoscopy.

CONCLUSION

The virtual reality simulator was an effecctive tool for teaching flexible cystoscopy.

Importance of early phase insulin secretion to intravenous glucose tolerance in subjects with type 2 diabetes mellitus

Insulin secretion is impaired in type 2 diabetes with the early response being essentially absent. The loss of this early insulin secretion is hypothesized to be important in the deterioration of glucose tolerance. To determine whether enhancement of the early-phase insulin response can enhance glucose tolerance, we administered 1) 120 mg nateglinide, an insulinotropic agent that enhances early insulin secretion; 2) 10 mg glyburide, which enhances the later phases of insulin secretion; or 3) placebo in random order to 21 subjects with type 2 diabetes (14 males and 7 females; aged 59.2 +/- 2.1 yr, x +/- SEM; body mass index 29.7 +/- 1.0 kg/m(2); fasting plasma glucose 8.1 +/- 0.1 mM). beta-Cell function was quantified as the incremental area under the curve for different time periods for the 5 h following iv glucose administration and glucose tolerance as the glucose disappearance constant (Kg) from 10 to 60 min. Insulin release commenced immediately after nateglinide administration, even before glucose injection, but this was not observed with glyburide. Both nateglinide and glyburide enhanced glucose-induced insulin release, compared with placebo (area under the curve -15-300 min: nateglinide 23,595 +/- 11,212 pM/min, glyburide 54,556 +/- 15,253 pM/min, placebo 10,242 +/- 2,414 pM/min). The profiles of insulin release demonstrated significant enhancement of release between -15 and 30 min for nateglinide, compared with glyburide and between 60 and 300 min for glyburide over nateglinide. Kg increased by 15% with nateglinide (0.87 +/- 0.04%/min), but it did not increase significantly with glyburide (0.79 +/- 0.04%/min), compared with placebo (0.76 +/- 0.04%/min). The enhancement of insulin release by glyburide resulted in a lower minimal glucose concentration with glyburide (3.8 +/- 0.2 mM), compared with nateglinide (5.0 +/- 0.2 mM) and placebo (5.9 +/- 0.2 mM). Thus, enhancement of the early phase of insulin secretion improves iv glucose tolerance, whereas delaying it by 30 min results in a slower rate of glucose disappearance for the first 2 h after iv glucose administration. Further, the differences in the kinetics of nateglinide and glyburide action results in continued insulin release with glyburide despite the fact that glucose levels have returned to basal, thus resulting in a further reduction in glucose levels and a lower nadir.

The issue of prophylactic antibiotics prior to flexible cystoscopy

OBJECTIVE

The aim of this study was to determine whether single-dose parenteral antibacterial therapy significantly alters the rate of infection in patients undergoing flexible cystourethroscopy.

PATIENTS AND METHODS

162 patients were studied prospectively having either received parenteral antibacterial chemoprophylaxis prior to flexible cystourethroscopy or not. Pre- and postprocedure mid stream samples of urine (MSSU) were obtained to objectively evaluate the presence of infection.

RESULTS

Gentamicin prophylaxis reduced the rate of post-cystoscopy-positive MSSUs from 21 to 5%.

CONCLUSION

The surprisingly high rate of infection after flexible cystoscopy was significantly reduced by a single dose of gentamicin.

Do patients with rheumatoid arthritis established on methotrexate and folic acid 5 mg daily need to continue folic acid supplements long term?

BACKGROUND

It is postulated that some aspects of methotrexate toxicity may be related to its action as an anti-folate. Folic acid (FA) is often given as an adjunct to methotrexate therapy, but there is no conclusive proof that it decreases the toxicity of methotrexate and there is a theoretical risk that it may decrease the efficacy of methotrexate.

OBJECTIVES

To look at the effect of stopping FA supplementation in UK rheumatoid arthritis (RA) patients established on methotrexate <20 mg weekly and FA 5 mg daily, to report all toxicity (including absolute changes in haematological and liver enzyme indices) and to report changes in the efficacy of methotrexate.

METHODS

In a prospective, randomized, double-blind, placebo-controlled study, 75 patients who were established on methotrexate <20 mg weekly and FA 5 mg daily were asked to stop their FA and were randomized to one of two groups: placebo or FA 5 mg daily. Patients were evaluated for treatment toxicity and efficacy before entry and then at intervals of 3 months for 1 yr.

RESULTS

Overall, 25 (33%) patients concluded the study early, eight (21%) in the group remaining on FA and 17 (46%) in the placebo group (P = 0.02). Two patients in the placebo group discontinued because of neutropenia. At 9 months there was an increased incidence of nausea in the placebo group (45 vs. 7%, P = 0.001). The placebo group had significantly lower disease activity on a few of the variables measured, but these were probably not of clinical significance.

CONCLUSIONS

It is important to continue FA supplementation over the long term in patients on methotrexate and FA in order to prevent them discontinuing treatment because of mouth ulcers or nausea and vomiting. Our data suggest that FA supplementation is also helpful in preventing neutropenia, with very little loss of efficacy of methotrexate.

Relationship of telomeres and p53 in aging bovine corneal endothelial cell cultures

PURPOSE

To demonstrate a relationship between telomere lengths and levels of p53 in cultured bovine corneal endothelial cells (CECs) during aging.

METHODS

Bovine CECs were grown and aged as long-term cultures. Telomere lengths were determined directly on gels with 32P probes after treatment of isolated DNA with RsaI and HinfI. Protein p53 was determined using an enzyme-linked immunosorbent sandwich assay. Cellular aging and the development of replicative senescence were monitored by the appearance of senescent morphology and the beta-galactosidase assay.

RESULTS

Bovine CEC telomeres lost 4 kb (from 12.8 to 8.8 kb) over 1 year (89 population doublings [PDs]). The p53 levels in bovine CECs were initially small (approximately 60 pg/million cells), but rose 3.5-fold by culture age of 260 days (64 PDs). On initiation, cultured bovine CECs did not stain for the senescent marker beta-galactosidase. However, these cells stained at 89 PDs and senescent morphology was observed in the cultures at 64 PDs.

CONCLUSIONS

The data indicate an inverse relationship between telomere lengths (decreasing) and levels of p53 (increasing) in bovine CECs during aging. These properties may influence the ability of these cells to divide as they enter into replicative senescence.

Effects of mannitol on cultured corneal endothelial cell Na,K-ATPase activity

Mannitol was introduced into the media of bovine corneal endothelial cells grown in culture. This was accomplished in order to compare its influence on Na,K-ATPase activity with that of high levels of glucose that inhibit the enzyme. The study was conducted with the intent of showing possible adverse osmolar effects on enzyme activity. Mannitol was found to inhibit NA,K-ATPase when compared with mannitol-free medium (11 U vs. 202 U). However, this inhibition was significantly greater than that produced by high levels of glucose. When mannitol was introduced directly into the assay for the plasma membrane-extracted enzyme, the inhibition was as severe (14 U) as for that placed in the culture medium. By way of comparison, glucose introduced into the enzyme assay caused no significant inhibition (189 U). The mannitol concentration used was 20 mM and in the media there was an osmotic pressure of 347 mOsmol/kg. The high glucose concentration was 25 mM and the osmotic pressure in the media was 341 mOsmol/kg. These osmotic pressures were compared with that of the control medium (with 5 mM glucose), which generated a pressure of 308 mOsmol/kg. None of these values were judged sufficiently high to rupture cell plasma membranes or alter cell morphology as seen by vital staining and phase contrast microscopy. In addition, it was found that mannitol had no effect on cellular DNA, whereas a previous study showed that high glucose caused an increased unwinding of duplex DNA. This study suggests that mannitol inhibits endothelial cell Na,K-ATPase by a different mechanism than that of glucose. It further points out that osmotic effects may not be involved with either mechanism.

The danger of freely rocking cradles

OBJECTIVE

To assist the Adelaide State Coroner with his inquest into the death of two infants in South Australia, and to assist the Department of Public and Consumer Affairs develop Australian Standards for rocking cradles.

METHODOLOGY

A sample of each brand of new cradle commercially available in South Australia was examined. Videotapes were made of 11 healthy infants in rocking cradles to examine how they moved and how they reacted in different positions.

RESULTS

Many cradles had insecure locking pins. Infants in a cradle tilted at 10 degrees greater, face down with the side of the face against the bars, and an aim trapped between the body and bars or through the bars, were unable to obtain a clear airway unless a dummy was in the mouth.

CONCLUSIONS

Infants should never be left unattended in freely rocking cradles. Australian Standards should recommend locking pins be bolted into place and that cradles cannot tilt to greater than 5 degrees.

Caregiver education: feminist or male model?

Most nurses have become aware that they work in patriarchal organizations and understand how oppressive and destructive this is to their career and their work. Few nurses recognize that this same male model dominates many nursing education programs, even those designed, delivered, and controlled by nurses. A study was undertaken to determine the learning needs of critical care nurses in Atlantic Canada and identify obstacles that prevented them from meeting their needs. The findings and the subsequent development of an education program are described. The findings are related to feminist values and feminist-based models of education that seem to be congruent with women's needs.

Pain assessment from patients with burns and their nurses

We investigated pain experienced during burn wound debridement. Forty-nine adult patients with burns and 27 nurses submitted 123 pairs of visual analog scale pain ratings for burn wound debridements. While patients' overall visual analog scale pain scores were found to be evenly distributed, worst pain scores yielded a bimodal distribution with groups centered around means of 2.0 (low pain group) and 7.0 (high pain group). Low and high pain groups did not differ in age, sex, or total body surface area burned. Patient and nurse pain ratings were found to be highly correlated. According to one researcher's criteria, 53% of nurse pain ratings were accurate. Accuracy of nurses' ratings was unrelated to nursing experience or educational level. Future strategies are presented for comparing high and low pain groups and increasing nurse pain rating accuracy.

Low-molecular-weight peptides in corneal tissue culture media and in bovine aqueous fluid

Eight putative, low-molecular-weight peptides have been found in the media of bovine corneal tissue cocultures and in bovine aqueous fluid. By investigating amine fluid extracts from these sources by HPLC, possible amino acids, vitamins and urea were eliminated as the unknown peaks of interest. The molecular weights of these substances were equal to or less than 1,000 D. The peaks did not correspond to glutathione or bradykinin either which fall in this molecular weight range. As the cultures aged from 10 to 32 days, it was found that 5 of the 8 peptides varied in concentration. Five peptides increased in concentration to day 17 and slowly decreased afterwards. Efforts are not directed toward the identification of these peptides.

Adjunctive interventions for burn pain control: comparison of hypnosis and ativan: the 1993 Clinical Research Award

Thirty-two patients hospitalized for the care of major burns were randomly assigned to groups that received hypnosis, lorazepam, hypnosis with lorazepam, or placebo controls as adjuncts to opioids for the control of pain during dressing changes. Analysis of scores on the Visual Analogue Scale indicated that although pain during dressing changes decreased over consecutive days, assignment to the various treatment groups did not have a differential effect. This finding was in contrast to those of earlier studies and is likely attributable to the low baseline pain scores of subjects who participated. A larger number of subjects with low baseline pain ratings will likely be necessary to replicate earlier findings. The results are argued to support the analgesic advantages of early, aggressive opioid use via PCA or through careful staff monitoring and titration of pain drugs.

Alteration of ATPase activity and duplex DNA in corneal cells grown in high glucose media

An investigation was made on the possible effects of high levels (450 mg/dl) of glucose on the activities of Na,K-ATPase [E.C. (Enzyme Commission) 3.6.1.37] and Mg-ATPase (E.C. 3.6.1.4) in plasma membrane preparations of bovine corneal endothelial cells grown in tissue culture. The activities of these enzymes were compared with the activities of the same enzymes from cells grown in low or "fasting" levels (90 mg/dl) of glucose. All activities were assayed from cells that were secondary cultures (15-25 days after trypsinization). The results indicated a 76% decrease in activity for Na,K-ATPase (0.04 units in high glucose vs. 0.17 units in low glucose). The activity for Mg-ATPase also decreased by 33% (0.24 units in high glucose vs. 0.36 units in low glucose). A t-test for significance indicated that the loss of activity in both enzymes was highly significant (p < 0.001) in the high glucose media. Assays for ATPase activity of plasma membranes were also made directly in high glucose after removal of the membranes from cells grown in low-glucose media. However, those membrane ATPases showed no significant decrease in activity. Tests for DNA damage of cells grown in the presence of high levels of glucose indicated a 15.5% change (decrease) in the amount of double-stranded DNA remaining after alkali treatment. This change was highly significant also (p < 0.001). These data suggest that the diabetic state may negatively affect membrane-bound ATPases of the corneal endothelium and further point to the possibility of an altered synthetic rate of ATPase polypeptides as a result of DNA damage.

The inhibition of Na, K-ATPase, and Mg-ATPase by timolol maleate in cultured non-pigmented epithelial cells of the ciliary body

Bovine, non-pigmented, ciliary body epithelial cells were isolated and grown in culture to determine whether timolol maleate might affect the activity of their plasma membrane ATPases. The possible effects were tested in drug concentrations in a range of 5 x 10(-19) to 5 x 10(-5) M over an incubation period of 30 min at 37 degrees. Assays of specific activity showed that the drug significantly (p less than .001 for most concentrations) inhibited both Na,K-ATPase and Mg-ATPase. However, the inhibition was partially reversed in concentrations greater than 10(-6) M for Na,K-ATPase and 10(-5) M for Mg-ATPase. The latter enzyme also indicated a second partial reversal in activity at concentrations between 10(-12) and 10(-9) M. These reversals in activity suggest that more than one binding site is involved in the inhibition of both enzymes. Since Na,K-ATPase in non-pigmented, ciliary body cells is responsible for the generation of aqueous fluid and the intraocular pressure (IOP), this inhibition demonstrates a possible mechanism for the pharmacological action of timolol maleate in lowering IOP.

Age as a function of ATPase activity in cultured corneal endothelial cells

As cells grown in tissue culture age, they typically become altered when compared to their in vivo counterparts. Bovine corneal endothelial cells were grown in culture for periods up to 60 days (primary = 10 days; secondary = 50 days). The plasma membrane enzymes: Na+K+ ATPase and Mg2+ ATPase were assayed for specific activity at selected intervals throughout the growth periods. In primary cultures, it was found that Na+K+ ATPase was quite low at 5 days (0.05 units), but increased fourfold at 10 days (0.22 units). By contrast, Mg2+ ATPase changed little over the same period. Tissue cultures grown secondarily had Na+K+ ATPase activity fall 0.3 units (0.52 to 0.22) for 35 days after a single trypsinization. After five trypsinizations over a 50-day period, the activity fell 0.23 units (0.33 to 0.10). The alterations in Mg2+ ATPase activity were more complex in secondary cultures. In the instance in which a single trypsinization was used, the activity fell 0.15 units at day 20, rose 0.12 units (above the starting value) at day 25, then returned to the initial level by day 35. When multiple trypsinizations were used, the activity fell 0.06 units by day 30, then remained stable for the duration. The data may be indicative of mechanisms such as receptor alteration, feedback inhibition and genetic instability when these cells are grown in culture.

The acidification response of normal subjects to ammonium chloride using a 3-day loading test

The acidification response to NH4 Cl loading (0.1 g/kg bw/day) was tested in 16 normal healthy subjects in the basal fasting state on Day 4, the subjects having taken the salt daily for the 3 previous days. The response was measured in terms of blood pH and in urine, creatinine, phosphate, pH, titratable acidity, ammonium, net acidity and creatinine clearance. To minimise inter-subject variation the urine values were adjusted to a standard body surface area of 1.73 m2. A normal range for the blood pH of the mean value +/- 2 SD, encompassed the observed range of values. However, to fit the observed range of acid-base values in urine into the 2 SD range required a logarithmic transformation of the data. Statistical analysis confirmed a significant correlation between blood [H+] net acid secretion, urine titratable acidity and ammonium. Urine net acid secretion was positively correlated with urinary phosphate, titratable acidity and ammonium.

Sodium and potassium saturation kinetics of Na+K+-ATPase in plasma membranes from corneal endothelium: fresh tissue vs. tissue culture

The maximal velocity (Vmax) and the apparent dissociation constant (K0.5) of Na+K+-ATPase have each been estimated with respect to sodium and potassium ion activation. These estimations were made from the enzymatic activity of plasma membrane preparations derived from bovine corneal endothelial cells. The determinations were made on cells obtained from fresh tissue and from secondary tissue cultures. Two methods were used to obtain the estimates: the first used a combination of Eadie-Hofstee and Hill plots; the second used Eisenthal-Cornish-Bowden plots. The Vmax for sodium was 5.58-5.60 mumol Pi/mg protein/30 min for fresh tissue vs. 2.00-1.80 mumoles Pi/mg protein/30 min for tissue cultures. The corresponding K0.5 values were 62-57 mM (fresh tissue) vs. 7.9-6.7 mM (tissue culture). Vmax for potassium was 4.28-4.00 mumoles Pi/mg protein/30 min for fresh tissue vs. 1.37-1.34 mumoles Pi/mg protein/30 min for tissue cultures. The corresponding K0.5 values were 3.3-3.1 mM (fresh tissue) and 1.7-1.7 mM (tissue culture). The results indicate a lowered activity and change in affinity of the enzyme for the two ions in tissue cultures compared to fresh tissues. The detergent Lubrol W-X increased activity in both tissue sources. Sonication had no significant effect on the activity. Variations in pH (7-9) indicated that the highest activity was obtained at pH 7.8 for the enzyme in tissue culture while activity was highest at pH 8.0 for the enzyme in fresh tissues. These differences in kinetic activity suggest a response to changes in the ion requirements of these cells due to their environment, developmental stage or some other parameter.