Second generation anti-androgens and androgen deprivation therapy with radiation therapy in the definitive management of high-risk prostate cancer

BACKGROUND

Evolving data suggest that men with high-risk localized prostate cancer may benefit from more potent androgen receptor inhibition in the context of curative intent radiotherapy. Recently updated American Society for Clinical Oncology (ASCO) evidence-based guidelines and the National Comprehensive Cancer Network (NCCN) Guidelines have updated recommendations for the consideration of adding second generation anti-androgens to androgen deprivation therapy (ADT) in men receiving radiation therapy (RT) for noncastrate locally advanced high and very high risk nonmetastatic or node positive prostate cancer.

METHODS AND RESULTS

We conducted a comprehensive review of existing published and abstract presented evidence behind RT with ADT for the definitive management of high-risk prostate cancer, particularly focused on the current phase II and III trial evidence for the addition of second generation anti-androgens to ADT in definitive RT treatment of high-risk prostate cancer and specifically focused on the recent STAMPEDE trial results with abiraterone acetate. We review the biological mechanisms in which second generation anti-androgens may help mitigate ADT resistance and provide radiosensitization through inhibition of DNA repair. Finally, we discuss ongoing clinical trials of potent androgen receptor (AR) inhibitors with ADT in this non-metastatic high-risk radiotherapy setting that may inform on future treatment guidelines.

CONCLUSIONS

Recent data suggest an overall survival benefit as well as increased probabilities of disease free and metastasis free survival in men with high and very high-risk localized, node positive, and oligometastatic hormone sensitive prostate cancer with abiraterone acetate and prednisone and support the use of potent AR inhibitors in this setting after informed decision making.

Prostate MRI in Stereotactic Body Radiation Treatment Planning and Delivery for Localized Prostate Cancer

Prostate MRI is increasingly being used to make diagnoses and guide management for patients receiving definitive radiation treatment for prostate cancer. Radiologists should be familiar with the potential uses of prostate MRI in radiation therapy planning and delivery. Radiation therapy is an established option for the definitive treatment of localized prostate cancer. Stereotactic body radiation therapy (SBRT) is an external-beam radiation therapy method used to deliver a high dose of radiation to an extracranial target in the body, often in five or fewer fractions. SBRT is increasingly being used for prostate cancer treatment and has been recognized by the National Comprehensive Cancer Network as an acceptable definitive treatment regimen for low-, intermediate-, and high-risk prostate cancer. MRI is commonly used to aid in prostate radiation therapy. The authors review the uses of prostate MRI in SBRT treatment planning and delivery. Specific topics discussed include the use of prostate MRI for identification of and dose reduction to the membranous and prostatic urethra, which can decrease the risk of acute and late toxicities. MRI is also useful for identification and appropriate dose coverage of the prostate apex and areas of extraprostatic extension or seminal vesicle invasion. In prospective studies, prostate MRI is being validated for identification of and dose intensification to dominant intraprostatic lesions, which potentially can improve oncologic outcomes. It also can be used to evaluate the placement of fiducial markers and hydrogel spacers for radiation therapy planning and delivery. ^©RSNA, 2022.

Novel Coronavirus International Public Health Emergency: Guidance on Radiation Oncology Facility Operation

PURPOSE

The current situation of coronavirus disease 2019 (COVID-19) is rapidly evolving. Radiation therapy facilities are places of concentrated patient interactions. Oncology patients with immunosuppression are at a higher risk for contracting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and easily developing severe postinfection events during the SARS-CoV-2 outbreaks. This review aimed to provide some guidance and be a reference to medical professionals in radiation oncology so that they may provide oncology patients with safe and high-quality care.

METHODS AND MATERIALS

This paper discussed how radiation therapy departments or centers can most effectively respond to this public health emergency through summarizing the procedures and protocols implemented at hospitals in ShenZhen, China.

RESULTS

The impact of the virus in radiation therapy facilities can be mitigated and managed with appropriate and timely implementation of infection control procedures and protocols.

CONCLUSIONS

In the face of acute infectious disease, it is critical to maintain strict infectious disease control procedures and to create a clear clinical workflow protocol to best protect medical staff and patients from the effect of acute infectious diseases.

Abstract P6-17-28: Outcomes of real-world use of eribulin plus trastuzumab for HER2-positive metastatic breast cancer

Background

Eribulin mesylate is approved for the treatment of metastatic breast cancer (mBC) after two prior chemotherapy regimens including an anthracycline or a taxane in either the metastatic or adjuvant setting. Eribulin in combination with trastuzumab (E+T) has demonstrated tolerability and anti-tumor activity in phase I and II trials but is not FDA-approved for the treatment of HER2-positive mBC. Case series and retrospective research have noted the use of E+T in clinical practice. We sought to describe patient characteristics and long-term outcomes of treatment with E+T for HER2-positive mBC patients treated outside of clinical trials in the US.

Methods

US-based community oncologists from an open network of over 7,000 oncologists, hematologists, and urologists were invited to participate in identifying HER2-positive mBC patients treated with E+T between 01/01/11 and 12/31/13 outside of clinical trials. Data were collected from 03/18/2016 until 09/01/2016. Providers completed an electronic case report form (CRF) by abstracting data on disease characteristics, treatment patterns, disease response (per provider assessment), adverse events (Aes), and date of death. Duration of treatment and overall survival (OS) were calculated from the initiation of the E+T regimen. The target sample size was 60 patients and patients were selected according to resource available for chart data abstraction.

Results

Twenty-three providers submitted CRFs for 62 total patients. After data collection, 59 of 62 submitted records were validated for analysis. At mBC diagnosis, 69.4% of patients were ER/PR negative and 42.4% of patient had de novo stage IV disease. At initiation of E+T, the median age was 57 years and 81.4% were ECOG-OS 0/1. Mean length of follow-up from the initiation of any therapy was 33.6 months. Twenty-two (37.3%) patients initiated E+T as their first- or second-line of treatment; those remaining were in third-line or greater. At initiation of E+T, 72.8% of patients had prior treatment with trastuzumab in combination with chemotherapy, 25.4% had prior trastuzumab in combination with pertuzumab and chemotherapy, and 16.9% had received TDM-1. Mean duration of E+T treatment was 5.2 months (SD=2.4). A response (complete [CR] or partial [PR]) was recorded by the providers for 64.4% of patients (not independently verified). The most common Aes reported were fatigue (67.8%), weakness (50.8%), decreased appetite (28.8%), decreased hemoglobin (27.1%), peripheral neuropathy (25.4%), and neutropenia (18.6%). At the end of the study period, 34 patients (57.6%) were deceased; the median OS from the initiation of E+T was 23.9 months (95% CI: 17.8-30.4).

Conclusions

In a small cohort of patients treated with E+T in the community setting, the observed response rate of 64.4% (CR+PR) was comparable to that of a prior phase II trial of E+T which reported an ORR with first-line E+T of 71.2% overall, 77.4% among T-naïve and 61.9% in T-pretreated patients. Further research is warranted to examine the tolerability and efficacy of E+T for metastatic HER2-positive breast cancer patients in different treatment settings.

Citation Format: Mougalian SS, Copher R, McAllister L, Radtchenko J, Wang EC, Broscious M, Yu H-T, Kish J. Outcomes of real-world use of eribulin plus trastuzumab for HER2-positive metastatic breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-17-28.

Leptomeningeal failure in patients with breast cancer receiving stereotactic radiosurgery for brain metastases

PURPOSE

Prior studies suggest a high incidence of leptomeningeal failure (LMF) in breast cancer metastatic to brain. This study examines breast cancer-specific variables affecting development of LMF and survival after Gamma-Knife Radiosurgery (GKS).

METHODS

Between 2000-2010, 149 (breast) and 658 other-histology patients were treated with GKS. Hormone/HER2, age, local/distant brain failure, prior craniotomy, and prior whole-brain radiotherapy (WBRT) were assessed. Median follow-up was 54months (range, 0-106). Serial MRI determined local and distant-brain failure and LMF. Statistical analysis with categorical/continuous data comparisons were done with Fisher's-exact, Wilcoxon rank-sum, log-rank tests, and Cox-Proportional Hazard models.

RESULTS

Of 149 patients, 21 (14%) developed LMF (median time of 11.9months). None of the following predicted for LMF: Her2-status (HR=0.49, p=0.16), hormone-receptor status (HR=1.15, p=0.79), prior craniotomy (HR=1.58, p=0.42), prior WBRT (HR=1.36, p=0.55). Non-significant factors between patients that did (n=21) and did not (n=106) develop LMF included neurologic death (p=0.34) and median survival (8.6 vs 14.2months, respectively). Breast patients who had distant-failure after GKS (65/149; 43.6%) were more likely to later develop LMF (HR 4.2, p=0.005); including 15/65 (23%) patients who had distant-failure and developed LMF. Median time-to-death for patients experiencing LMF was 6.1months (IQR 3.4-7.8) from onset of LMF. Median survival from LMF to death was much longer in breast (6.1months) than in other (1.7months) histologies CONCLUSION: Breast cancer patients had a longer survival after diagnosis of LMF versus other histologies. Neither ER/PR/HER2 status, nor prior surgery or prior WBRT predicted for development of LMF in breast patients.

Gamma Knife radiosurgery for brain metastases from gastrointestinal primary

INTRODUCTION

In this study, we assessed clinical outcomes of patients with brain metastases from a gastrointestinal (GI) primary cancer and patterns of failure after stereotactic radiosurgery including failure within the radiosurgical volume, distant failure and leptomeningeal failure (LMF). We also assessed other factors associated with the patients' neurologic and extraneuraxial disease that may affect clinical outcomes.

METHODS

We reviewed our institutional series of 62 consecutive patients with brain metastases treated with stereotactic radiosurgery, which included 17 patients with oesophageal, 44 patients with colorectal and one patient with anal canal primary. The median marginal dose to the radiosurgery volume was 17 Gy (range 10-24 Gy). Thirteen patients were treated with whole-brain radiotherapy (WBRT) prior to GKS.

RESULTS

The median dose delivered to the margin of the tumour was 17 Gy (range: 10-24 Gy). The median largest tumour diameter was 2.7 cm (range: 0.60-6.1 cm). The median overall survival (OS) was 7.1 months with a median follow-up of 6.1 months and a range of 0-31.7 months. Freedom from local failure was 86.5% and 62.2% at 6 and 12 months respectively. Freedom from distant failure was 73.2% and 42.2% at 6 and 12 months, respectively, and 40% of patients died of neurologic death. LMF occurred in seven patients, all of whom had colorectal primaries. Multivariate analysis revealed that craniotomy for resection of brain metastasis (HR = 2.63, P < 0.02), an absence of extracranial disease (HR = 2.28, P < 0.03), and prolonged time to distant brain failure (HR = 2.85, P < 0.01) predicted for improved survival.

CONCLUSIONS

Colorectal cancer metastases tend to have a higher rate of leptomeningeal failure than other types of GI cancer metastases. Radiosurgical management of brain metastases from GI primary represents an acceptable management option. Neurologic death remains problematic.

Nanoparticles and their applications in cell and molecular biology

Nanoparticles can be engineered with distinctive composition, size, shape, and surface chemistry to enable novel techniques in a wide range of biological applications. The unique properties of nanoparticles and their behavior in biological milieu also enable exciting and integrative approaches to studying fundamental biological questions. This review will provide an overview of various types of nanoparticles and concepts of targeting nanoparticles. We will also discuss the advantages and recent applications of using nanoparticles as tools for drug delivery, imaging, sensing, and for the understanding of basic biological processes.

Effect of drug release kinetics on nanoparticle therapeutic efficacy and toxicity

The effects of nanoparticle (NP) properties, such as size, shape and surface charge, on their efficacy and toxicity have been studied extensively. However, the effect of controlled drug release on NP efficacy and toxicity has not been thoroughly evaluated in vivo. Our study aims to fill this knowledge gap. A key challenge in characterizing the relationship between drug release and therapeutic ratio is to fabricate NPs that differ only in their drug release profile but are otherwise identical. To overcome this challenge, we developed crosslinkable lipid shell (CLS) NPs, where the drug release kinetics can be modulated without changing any other NP property. Using CLS NPs with wortmannin and docetaxel as model drugs, we determined the relationship between the release kinetics and therapeutic efficacy and toxicity of the drugs. We have determined that drug release kinetics can affect the therapeutic efficacy of NP docetaxel and NP wortmannin in vitro and in vivo. Our study also demonstrates that a decrease in drug release kinetics can result in a decrease in the hepatotoxicity of CLS NP wortmannin. Using two model drugs, the current findings provide the first direct evidence that NP drug release profile is a critical factor in determining the NP therapeutics' efficacy and toxicity in vivo.

Differential cell responses to nanoparticle docetaxel and small molecule docetaxel at a sub-therapeutic dose range

Current preclinical evaluations of nanoparticle taxanes have focused on the effect of nanoparticle size and shape on the efficacy and toxicity. It is generally assumed that nanoparticle therapeutics have the same cellular response on tumor and normal cells as their small molecule counterparts. Here, we show that nanoparticle taxanes can mediate cellular effects distinct from that of small molecule taxanes at the sub-therapeutic dose range. Cells that are exposed to two polymeric nanoparticle formulations of docetaxel were found to undergo a different cell cycle and cell fate than those of cells that were exposed to small molecule docetaxel. Our results suggest that nanoparticle formulation of therapeutics can affect the therapeutic effect of its cargo.

FROM THE CLINICAL EDITOR

This study investigates the differences between subtherapeutic doses of docetaxel applied as small molecules vs. nanoparticle formulations, demonstrating differential effects on the cell cycle and overall cell fate. The study suggests that the carrier may change the therapeutic effects of its cargo, which has important implications on future research.

Preclinical evaluation of Genexol-PM, a nanoparticle formulation of paclitaxel, as a novel radiosensitizer for the treatment of non-small cell lung cancer

PURPOSE

A key research objective in radiation oncology is to identify agents that can improve chemoradiation therapy. Nanoparticle (NP) chemotherapeutics possess several properties, such as preferential accumulation in tumors, that are uniquely suited for chemoradiation therapy. To facilitate the clinical translation of NP chemotherapeutics in chemoradiation therapy, we conducted preclinical evaluation of Genexol-PM, the only clinically approved NP chemotherapeutic with a controlled drug release profile, as a radiosensitizer using non-small cell lung cancer (NSCLC) as a model disease.

METHODS AND MATERIALS

The physical characteristics and drug release profile of Genexol-PM were characterized. Genexol-PM's efficacy as a radiosensitizer was evaluated in vitro using NSCLC cell lines and in vivo using mouse xenograft models of NSCLC. Paclitaxel dose to normal lung and liver after Genexol-PM administration were quantified and compared with that after Taxol administration.

RESULTS

Genexol-PM has a size of 23.91 ± 0.41 nm and surface charge of -8.1 ± 3.1 mV. It releases paclitaxel in a controlled release profile. In vitro evaluation of Genexol-PM as a radiosensitizer showed it is an effective radiosensitizer and is more effective than Taxol, its small molecule counterpart, at the half maximal inhibitory concentration. In vivo study of Genexol-PM as a radiosensitizer demonstrated that it is more effective as a radiosensitizer than Taxol. We also found that Genexol-PM leads to lower paclitaxel exposure to normal lung tissue than Taxol at 6 hours postadministration.

CONCLUSIONS

We have demonstrated that Genexol-PM is more effective than Taxol as a radiosensitizer in the preclinical setting and holds high potential for clinical translation. Our data support the clinical evaluation of Genexol-PM in chemoradiation therapy for NSCLC.

Abstract 4530: Nanoparticle formulation of KU55933 as a potent radiosensitizer

KU55933 is a potent and specific inhibitor of the Ataxia Telangiectasia Mutated (ATM) protein. Given ATM's critical role in DNA damage repair, specifically double-strand break repair, KU55933 holds high potential as a radiosensitizer. Indeed, previous preclinical studies have demonstrated the radiosentization effect of KU55933. However, clinical translation of KU55933 as a radiosensitizer has been prevented due to concerns of its potential toxicity. Systemic administration of KU55933 would sensitize normal cells as well as cancer cells to the effects of radiotherapy. Such sensitization would not improve the therapeutic index of radiotherapy. Therefore, the key challenge in the translation of KU55933 is to identify methods that can selectively deliver KU55933 to tumors while minimizing normal tissue dose. While traditional drug delivery methods cannot overcome this challenge, the development of nanoparticle (NP) drug delivery vehicles offers a unique opportunity. NPs are known to preferentially accumulate in tumors while provide low drug dose to nearby normal tissues. We hypothesize that NP delivery of KU55933 can not only improve the therapeutic efficacy of KU55933, but also lower its toxicity. In this study, we engineered a NP formulation of KU55933 using a biodegradable lipid-polymer NP. We then compared the radiosensitization effect of NP KU55933 to that of KU55933 in vitro using the non-small cell lung cancer (NSCLC) cell lines H23, A549 and H460. Clonogenic survival assays showed that NP KU55933 is a more potent radiosensitizer than KU55933. The differential radiosensitization effect of both KU55933 formulations was also evaluated in a xenograft mouse model of NSCLC. We validated our in vitro results by demonstrating that NP KU55933 is more effective than KU55933 as radiosensitizer in flank xenograft models of NSCLC. To compare the toxicity of NP KU55933 and KU55933, we determined the skin toxicity after radiotherapy with the two drug formulations. We found lower skin toxicity in mice treated with the NP KU55933 than that for KU55933. In conclusion, our studies demonstrate that NP formulation of KU55933 can enhance the radiosensitization effect and decreases the toxicity in vitro and in vivo. Our results suggest that NP KU55933 holds potential for clinical translation.

Citation Format: Haydee Lara, Michael B. Foote, Edina C. Wang, Manish Sethi, Patricia Casbas-Hernandez, Andrew Z. Wang. Nanoparticle formulation of KU55933 as a potent radiosensitizer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4530. doi:10.1158/1538-7445.AM2013-4530

Abstract 4517: Differential cellular response to nanoparticle docetaxel and docetaxel at sub-therapeutic dose range

Nanoparticle (NP) formulations of taxanes overcome the need for excipients and improve the delivery of taxane therapeutics to tumors. These advantages have resulted in rapid clinical translation of NP taxanes and high interest in preclinical and clinical development of novel NP taxanes. However, the effects of NP taxanes on tumor cells compared to their small molecule counterparts have not been evaluated. Existing NP taxanes are polymeric NPs and release their cargo in a slow and controlled fashion. Due to this controlled release, the taxane concentration level and exposure time to a cell at any given time from NP taxanes are different from that of small molecule taxanes. We have utilized two distinct polymeric NP docetaxel formulations to study the influence of NP drug delivery of taxanes on tumor cells in vitro. We hypothesize that the cellular response to polymeric NP taxanes is different from that of small molecule taxanes due to the controlled release property.

We used docetaxel (Dtxl) as a model taxane therapeutic and studied tumor cell response to Docetaxel-PNP, a commercial polymeric NP formulation of Dtxl currently under clinical investigation, and folate-targeted nanoparticle docetaxel (FT-NP Dtxl), a targeted lipid-polymer NP formulation of Dtxl that was developed by our laboratory. The taxane formulations were evaluated using KB head and neck carcinoma. We performed liquid chromatography/mass spectrometry and determined that using the Dtxl equivalent dose of the Dtxl formulations provided the same intracellular concentration of Dtxl after 1 h exposure in KB cells. We demonstrated by fluorescence-activated cell sorting of the cell cycle distribution that NP Dtxl formulations and small molecule Dtxl have similar effects on KB tumor cells at therapeutic concentrations. However, cells treated with a sub-therapeutic concentration of NP Dtxl undergo a different progression through the cell cycle compared to cells treated with small molecule Dtxl, which suggests a difference in the cellular response between the Dtxl formulations. We validated the differential cellular response to sub-therapeutic doses of NP Dtxl and Dtxl by live cell imaging analysis of KB green fluorescent protein-histone 2B (GFP-H2B) expressing cells after treatment. We found that the cellular response of tumor cells to NP Dtxl is different from that of Dtxl at sub-therapeutic doses. In this dose range, we also found that the cellular response of cells to NP Dtxl is similar to that of Dtxl at a much lower dose, suggesting that controlled release property of NP Dtxl is responsible for the difference in the cellular response.

In conclusion, we have demonstrated that the cellular response of tumor cells to NP Dtxl is different from that to Dtxl at sub-therapeutic doses. We speculate that this difference is due to the controlled release property, which causes cells to be exposed to a lower concentration of Dtxl.

Citation Format: Edina C. Wang, Rebecca Sinnott, Michael E. Werner, Manish Sethi, Joel E. Tepper, Angelique W. Whitehurst, Andrew Z. Wang. Differential cellular response to nanoparticle docetaxel and docetaxel at sub-therapeutic dose range. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4517. doi:10.1158/1538-7445.AM2013-4517

Formulation of diblock polymeric nanoparticles through nanoprecipitation technique

Nanotechnology is a relatively new branch of science that involves harnessing the unique properties of particles that are nanometers in scale (nanoparticles). Nanoparticles can be engineered in a precise fashion where their size, composition and surface chemistry can be carefully controlled. This enables unprecedented freedom to modify some of the fundamental properties of their cargo, such as solubility, diffusivity, biodistribution, release characteristics and immunogenicity. Since their inception, nanoparticles have been utilized in many areas of science and medicine, including drug delivery, imaging, and cell biology(1-4). However, it has not been fully utilized outside of "nanotechnology laboratories" due to perceived technical barrier. In this article, we describe a simple method to synthesize a polymer based nanoparticle platform that has a wide range of potential applications. The first step is to synthesize a diblock co-polymer that has both a hydrophobic domain and hydrophilic domain. Using PLGA and PEG as model polymers, we described a conjugation reaction using EDC/NHS chemistry(5) (Fig 1). We also discuss the polymer purification process. The synthesized diblock co-polymer can self-assemble into nanoparticles in the nanoprecipitation process through hydrophobic-hydrophilic interactions. The described polymer nanoparticle is very versatile. The hydrophobic core of the nanoparticle can be utilized to carry poorly soluble drugs for drug delivery experiments6. Furthermore, the nanoparticles can overcome the problem of toxic solvents for poorly soluble molecular biology reagents, such as wortmannin, which requires a solvent like DMSO. However, DMSO can be toxic to cells and interfere with the experiment. These poorly soluble drugs and reagents can be effectively delivered using polymer nanoparticles with minimal toxicity. Polymer nanoparticles can also be loaded with fluorescent dye and utilized for intracellular trafficking studies. Lastly, these polymer nanoparticles can be conjugated to targeting ligands through surface PEG. Such targeted nanoparticles can be utilized to label specific epitopes on or in cells(7-10).

Characterization of cerebrovascular reactivity after craniectomy for acute brain injury

Analysis of slow waves in arterial blood pressure (ABP) and intracranial pressure (ICP) has been used as an index to describe cerebrovascular pressure-reactivity. It has been previously demonstrated that the pressure-reactivity index (PRx) can be used to reflect global cerebrovascular reactivity with changes in ABP. A positive PRx signifies a positive association between ABP and ICP, indicating a non-reactive vascular bed, while a negative PRx is reflective of intact cerebral autoregulation, where ABP waves provoke inversely correlated waves in ICP. To date, there has been no characterization of pressure-reactivity following decompressive craniectomy. In this prospective observational study, 33 patients who underwent surgery for acute brain injury with mass lesions for which the bone flap was left out were studied. The PRx was calculated as a moving correlation coefficient between 30 consecutive samples of values of ICP and ABP averaged for a period of 10 s. The time profiles of mean PRx values at 6-hourly intervals were analysed and compared with that in seven patients treated by medical therapy alone. The initial mean PRx 6 h after surgery was positive, indicative of disturbed pressure-reactivity. With time, PRx trended towards a more negative value, suggestive of an improving cerebrovascular autoregulatory reserve. The mean PRx 24 h after surgery was 0.28 (+/-0.26), while the mean PRx 72 h after surgery was 0.15 (+/-0.25) (p = 0.012). In contrast, the mean PRx in patients that were not decompressed did not change significantly with time (p = 0.357). Surgery in acute brain injury for which the bone flap is left out in anticipation of raised intracranial pressure in the postoperative period leads to an improved PRx as compared with controls. Craniectomy in this situation may have a contribution to the restoration of disturbed cerebrovascular pressure-reactivity.

Barbiturate therapy for patients with refractory intracranial hypertension following severe traumatic brain injury: its effects on tissue oxygenation, brain temperature and autoregulation

The aim of this study was to explore the effects of barbiturate coma on cerebral tissue oxygen tension and cerebrovascular pressure reactivity (PRx), as an index of cerebral autoregulation in severe head injury patients. This was a prospective observational clinical study of 12 patients with severe traumatic brain injury, carried out at a tertiary-level neurosurgical intensive care unit between April 2002 and May 2005. All patients received standard neurosurgical intensive care and monitoring. Probes for intracranial pressure (ICP), brain temperature (BT) and brain tissue oxygenation (PTiO2) were inserted into (noncontused) normal-looking white matter. Cerebrovascular PRx was measured as a moving correlation between ICP and arterial blood pressure. Barbiturate coma was instituted when ICP became refractory (ICP>20 mmHg). All data from the multimodal monitoring were digitally extracted and statistically analysed. The mean ICP decreased with barbiturate coma in eight of the 12 patients (75% of the patients), but only four achieved a value below 20 mmHg. Of eight patients with prebarbiturate PTiO2 levels above 10 mmHg, six had a further improvement in oxygenation. Thus, concordant favourable changes in ICP, PRx and PTiO2 with barbiturate coma were seen in those who survived. Effective response to barbiturates can be detected by improved PTiO2 and autoregulation (PRx) in severe head injury patients.

Functional differences between influenza A-specific cytotoxic T lymphocyte clones expressing dominant and subdominant TCR

We have shown that the dominance of CD8+ T cells expressing TCR Vbeta17 in the adult HLA-A*0201-restricted influenza A/M1(58-66)-specific response is acquired following first antigen exposure. Despite the acquired dominance of Vbeta17+ cells, subdominant M1(58-66)-specific clones expressing non-Vbeta17+ TCR persist in all individuals. To determine whether the affinity of the expressed TCR for the HLA-A*0201/M1(58-66) complex could influence functional properties, M1(58-66)-specific clones expressing subdominant (non-Vbeta17+) TCR were compared to cytotoxic T lymphocyte (CTL) clones expressing dominant (Vbeta17+) TCR. The Vbeta17+ CTL required up to 10,000-fold lower amounts of M1 peptide to mediate lysis compared to CTL clones expressing other Vbeta gene segments. All Vbeta17+ CTL clones tested bound HLA-A*0201/M1(58-66) tetramer, but two of three CTL clones expressing other TCR did not bind tetramer. The inability of non-Vbeta17+ CTL to bind tetramer did not correlate with phenotype, CD8 dependence or with cytokine production profiles. This suggests a limitation for the use of tetramers in examining subdominant T cell responses. Together these findings suggest that Vbeta17+ CTL which dominate the HLA-A*0201-restricted CTL response against influenza A are not functionally distinct from subdominant non-Vbeta17+ CTL. The dominance of Vbeta17+ CTL is likely to result from a competitive advantage due to superior CTL avidity for the HLA-A*0201/M1(58-66) complex.

Use of an interactive tool to assess patients' willingness-to-pay

Assessment of willingness to pay (WTP) has become an important issue in health care technology assessment and in providing insight into the risks and benefits of treatment options. We have accordingly explored the use of an interactive method for assessment of WTP. To illustrate our methodology, we describe the development and testing of an interactive tool to administer a WTP survey in a dental setting. The tool was developed to measure patient preference and strength of preference for three dental anesthetic options in a research setting. It delivered written and verbal formats simultaneously, including information about the risks and benefits of treatment options, insurance, and user-based WTP scenarios and questions on previous dental experience. Clinical information was presented using a modified decision aid. Subjects could request additional clinical information and review this information throughout the survey. Information and question algorithms were individualized, depending on the subject's reported clinical status and previous responses. Initial pretesting resulted in substantial modifications to the initial tool: shortening the clinical information (by making more of it optional reading) and personalizing the text to more fully engage the user. In terms of results 196 general population subjects were recruited using random-digit dialing in southwestern Ontario, Canada. Comprehension was tested to ensure the instrument clearly conveyed the clinical information; the average score was 97%. Subjects rated the instrument as easy/very easy to use (99%), interesting/very interesting (91%), and neither long nor short (72.4%). Most subjects were comfortable/very comfortable with a computer (84%). Indirect evaluation revealed most subjects completed the survey in the expected time (30 min). Additional information was requested by 50% of subjects, an average of 2.9 times each. Most subjects wanted this type of information available in the provider's office for use in clinical decision making (92%). Despite extensive pretesting, three "bugs" remained undiscovered until live use. We have demonstrated that the detailed information, complex algorithms, and cognitively challenging questions involved in a WTP survey can be successfully administered using a tailor-made, patient-based, interactive computer tool. Key lessons regarding the use of such tools include allowing the user to set the pace of information flow and tailor the content, engaging the user by personalizing the textual information, inclusion of tests of comprehension and offering opportunities for correction, and pretesting by fully mimicking the live environment.

Methodology standards associated with quality reporting in clinical studies in pediatric surgery journals

BACKGROUND/PURPOSE

Reports of clinical trials often lack adequate descriptions of design and analysis; recent attention has focused on improving this omission so readers can properly assess the strength of the findings and draw their own conclusions. Similar analysis of study design and methodologic standards associated with quality reporting has not been carried out for pediatric surgery journals.

METHODS

All studies (n = 642) published in 1998 in Journal of Pediatric Surgery (JPS) and Pediatric Surgery International (PSI), were reviewed for demographic data and study design. The frequency of reporting of 11 basic elements of design and analysis was evaluated in randomized clinical trials (RCT), nonrandomized clinical trials (NRCT), and retrospective cohorts (RC) from JPS by consensus of 2 assessors.

RESULTS

Of the 642 studies, 17% of articles (111 of 642) were classified as clinical studies. Sixty-three were comparative studies and consisted of RC (n = 48), NRCT (n = 12), and RCT (n = 3). Two-thirds of articles published were either case reports or case series (431 of 642), and 16% were basic science articles. Demographic analysis showed a wide range of topics addressed, 4 authors per article, and multiple country of origin of authors. More than 66% of all RCT in JPS reported on eligibility criteria, admission before allocation, random allocation, method of randomization, patients' blindness to treatment, treatment complications, statistical analyses, statistical methods, loss to follow-up, and statistical methods; 2 elements of design and analysis, however, were poorly reported: blind assessment of outcome (33%) and power (17%).

CONCLUSIONS

There were few randomized, controlled trials in pediatric surgery journals, and further attention should be given to evaluate the causal factors. Nine elements of quality reporting were well reported; however, 2 others were poorly reported; this may improve if editors of pediatric surgical journals provide authors with guidelines on how to report clinical trial design and analysis.

DR3 regulates negative selection during thymocyte development

DR3 (Ws1, Apo3, LARD, TRAMP, TNFSFR12) is a member of the death domain-containing tumor necrosis factor receptor (TNFR) superfamily, members of which mediate a variety of developmental events including the regulation of cell proliferation, differentiation, and apoptosis. We have investigated the in vivo role(s) of DR3 by generating mice congenitally deficient in the expression of the DR3 gene. We show that negative selection and anti-CD3-induced apoptosis are significantly impaired in DR3-null mice. In contrast, both superantigen-induced negative selection and positive selection are normal. The pre-T-cell receptor-mediated checkpoint, which is dependent on TNFR signaling, is also unaffected in DR3-deficient mice. These data reveal a nonredundant in vivo role for this TNF receptor family member in the removal of self-reactive T cells in the thymus.

Cost-effectiveness analysis of budesonide aqueous nasal spray and fluticasone propionate nasal spray in the treatment of perennial allergic rhinitis

BACKGROUND

An economic evaluation was performed analyzing direct medical costs in Canada for the treatment of perennial allergic rhinitis (PAR) with budesonide aqueous nasal spray and fluticasone propionate nasal spray. Three hundred fourteen patients with at least a 1-year history of PAR were randomized into a double-blind, parallel-group study of 6 weeks' duration. The treatments were daily doses of budesonide 256 microg, fluticasone propionate 200 microg, or placebo. Both active treatments produced significantly lower mean scores for overall nasal symptoms compared with placebo, and both were well tolerated. Budesonide was significantly more effective than fluticasone in reducing "blocked nose."

METHOD

A retrospective cost-effectiveness analysis utilizing the clinical trial data was performed on the total costs of (1) budesonide-based and (2) fluticasone-based treatment strategies, including the relative importance of the drug costs in both strategies.

RESULTS

The average treatment cost per patient in Canada over 12 months in the budesonide group was CAD 389.85 which was 23.3% lower than in the fluticasone group, which was CAD 508.06, due to lower drug acquisition costs (for the year 1998).

CONCLUSION

Budesonide aqueous nasal spray was shown to be more cost-effective than fluticasone propionate nasal spray in the treatment of perennial allergic rhinitis. This result is valid in the province of Ontario, Canada and in many other settings with the same structure of relative prices. The result is mainly driven by a difference in drug cost.

Vallecular cyst: an uncommon cause of stridor in newborn infants

Vallecular cyst, a rare but generally benign lesion in the larynx, may cause stridor and even life-threatening airway obstruction in early infancy. We retrospectively studied 14 cases of newborn infants with vallecular cyst. There was no gender predilection and most cases were full-term and appropriate for gestational age. The clinical presentations included stridor, chest wall retraction, feeding difficulties and failure to thrive. Laryngomalacia was the most common associated anomaly. Flexible laryngoscopy was sufficient for diagnosing the vallecular cyst and larygmalacia. Maintenance of airway patency, nutritional support, and de-roofing of the cyst were the mainstays of management.

CONCLUSION

Vallecular cyst should be included in the differential diagnosis of stridor in newborn infants. Respiratory and feeding difficulties in these patients can be dramatically improved after appropriate surgical removal of the cyst.

Methadone treatment during pregnancy

OBJECTIVE

To review the literature on methadone use by pregnant women.

DATA SOURCES

A search was conducted on CINAHL, MEDLINE, and PSYCHINFO under "pregnancy" and "methadone."

STUDY SELECTION

Articles published between 1988-1998 were reviewed and chosen based upon relevance to the objective.

DATA EXTRACTION

Data were extracted and organized under the following headings: effects of methadone on pregnancy outcome, management of the pregnant woman on methadone, and implications of social and political policies for pregnant women who use opiates.

DATA SYNTHESIS

Methadone treatment is most effective for pregnant women who receive care in a comprehensive service center. Few systematic investigations exist concerning methadone maintenance during pregnancy, thus no formal guidelines for management exist. Changes in federal policies for drug treatment and welfare regulations will challenge health care professionals who provide treatment for opiate-dependent pregnant women.

CONCLUSIONS

Treatment with methadone is the standard of care for the opiate-using pregnant woman, despite findings challenging its benefits and efficacy in women who continue to use illicit drugs.

A central role for alpha beta T cells in the pathogenesis of murine lupus

We have previously shown that female transgenic mice expressing IFN-gamma in the epidermis, under the control of the involucrin promoter, develop inflammatory skin disease and a form of murine lupus. To investigate the pathogenesis of this syndrome, we generated female IFN-gamma transgenic mice congenitally deficient in either alpha beta or gamma delta T cells. TCR delta-/- transgenics continued to produce antinuclear autoantibodies and to develop severe kidney lesions. In contrast, TCR beta-/- IFN-gamma transgenic mice failed to produce antinucleosome, anti-dsDNA, or antihistone autoantibodies, and kidney disease was abolished. Both alpha beta- and gamma delta-deficient transgenics continued to develop IFN-gamma-associated skin disease, lymphadenopathy, and splenomegaly. The data show that the autoantibody-mediated pathology of murine lupus in IFN-gamma transgenic mice is completely alpha beta T cell dependent and that gamma delta T cells cannot drive autoantibody production. These results imply that production of antinuclear autoantibodies in IFN-gamma transgenic animals is Ag driven, and we identified clusters of apoptotic cells in the epidermis of the mice as a possible source of self Ags. Our findings emphasize the relevance of this murine lupus model to the human disease.

The measurement of stress-related immune dysfunction in psychoneuroimmunology

In recent years there has been a dramatic increase in research dedicated to the psycho-behavioural modulation of immune function, i.e. the field of Psychoneuroimmunology (PNI). This has led, necessarily, to the use of several in vitro and in vivo techniques in attempts to delineate the relationship between these two phenomena. However, since the field's inception, considerable uncertainty has existed over the significance of the immune outcomes detected and this has been compounded by the equivocal nature of some of the published data. A great deal of this uncertainty could, however, be overcome if a clearer understanding was achieved on the advantages and limitations conferred by the manifold immune assays described in the literature. This would, in turn, encourage their more appropriate use within PNI. Hence, in this review we describe the rationale behind, and offer an evaluation of, some of the more frequently used in vitro and in vivo immunological and virological techniques. We hope that a clear understanding of the rationale behind such assays and their inherent advantages and limitations will inform the discussion of the significance of stress-related immune impairment.

Applying epidemiology-based outcomes research to clinical decision-making. A hypothetical model of biotechnology therapy in gram-negative sepsis

OBJECTIVE

Sepsis occurs in a heterogeneous population. A prospective nationwide surveillance study found that populations stratified by infection type had significant differences in the incidence of sepsis syndrome, rate of complications and mortality. The objective of this study was to explore whether successful identification of population-specific risk factors for disease-associated morbidity and mortality may allow for more accurate assessment of the cost effectiveness of treatment strategies.

DESIGN

A decision analytic model was developed using outcomes data on incidence and resolution of major complications in sepsis syndrome. Healthcare resource utilisation data were based on length of hospital stay, intensive care unit stay versus hospital ward stay, and cost of treating sepsis-related complications.

SETTING

This modelling study, conducted from the perspective of the healthcare institution, used actual outcomes data on 2 infection-specific patient populations.

PATIENTS AND PARTICIPANTS

The 2 populations studied were patients with nosocomial respiratory tract infection or community-acquired urinary tract infection who subsequently developed sepsis syndrome.

INTERVENTIONS

Treatment options modelled were standard therapy plus biotechnology therapy versus standard therapy alone in the treatment of gram-negative sepsis complications.

MAIN OUTCOME MEASURES AND RESULTS

The incremental cost-effectiveness ratios differed between the 2 study populations, due to differences in the incidence and rate of resolution of major sepsis-associated complications. The use of biotechnology therapy is always more cost effective in the respiratory tract infection population.

CONCLUSIONS

Cost-effectiveness results for a therapy may change when the epidemiology of the disease state is known and incorporated into the decision analytic model. An infection-specific approach is important in the treatment of sepsis.

Dysfunctional glucocorticoid receptor with a single point mutation ablates the CCAAT/enhancer binding protein-dependent growth suppression response in a steroid-resistant rat hepatoma cell variant

We used glucocorticoid-resistant and -sensitive hepatoma cell variants to characterize the mechanism of hepatoma cell resistance to the growth inhibitory effects of glucocorticoids. BDS1 hepatoma cells express transcriptionally active glucocorticoid receptors and undergo a stringent G1 cell cycle arrest in response to glucocorticoids that is dependent on the induced expression of the CCAAT/enhancer binding protein alpha (C/EBPalpha) transcription factor. In contrast, EDR1 hepatoma cells, which express normal levels of glucocorticoid receptors, fail to growth arrest or express C/EBPalpha when treated with glucocorticoids. Ectopic expression of wild-type rat glucocorticoid receptors into EDR1 cells restored the growth suppression response, suggesting a defect in the EDR1 receptor. DNA sequence analysis revealed a single point mutation causing a cysteine-to-tyrosine substitution at amino acid position 457 (C457Y-GR) in the zinc finger region of the glucocorticoid receptor that mediates both receptor-DNA and receptor-protein interactions. Glucocorticoid activation of the alpha1-acid glycoprotein (AGP) promoter, a liver acute-phase response gene, requires receptor-DNA binding as well as an interaction with C/EBPalpha. In contrast to the wild-type glucocorticoid receptor, ectopic expression of C/EBPalpha in EDR1 cells, or coexpression of C/EBPalpha along with the C457Y-GR into receptor-deficient EDR3 cells was required to partially restore glucocorticoid responsiveness of the AGP promoter by the EDR1 glucocorticoid receptor. Constitutive expression of the wild-type glucocorticoid receptor, but not the C457Y-GR mutant, was sufficient to restore the glucocorticoid growth suppression response to receptor-deficient EDR3 cells. Thus, we have identified a glucocorticoid-resistant hepatoma cell variant with a single point mutation in the zinc finger region of the glucocorticoid receptor gene that ablates the glucocorticoid growth suppression response and attenuates transcriptional activation of the AGP promoter.

Human cytomegalovirus infection downregulates expression of the cellular aminopeptidases CD10 and CD13

During the course of a productive infection, human cytomegalovirus (HCMV) has a sophisticated relationship with its host cell. An increasing number of virus-encoded genes are being identified which act specifically to usurp or modulate functions in the host cell associated with transcriptional control, cell signalling, and protein synthesis. While HCMV infection is associated with a general upregulation of cellular gene expression, the expression a small subset of cellular proteins, including the MHC-1 heavy chain and fibronectin, is downregulated. This study now identifies two additional cellular proteins, aminopeptidase N (CD13) and neutral endopeptidase (CD10), that are downregulated during HCMV infection. While aminopeptidase N and neutral endopeptidase exhibit no significant sequence homology, both are expressed on the cell surface and have very similar enzymatic properties. HCMV infection was associated with reduced surface expression and enzyme activity of CD13 and CD10, an apparent decrease in the rate of synthesis of both proteins in metabolic-labelling experiments, and inhibited glycosylation of the nascent CD13 and CD10 polypeptide chains that were synthesized. Levels of CD10 poly A+ RNA were suppressed efficiently at all stages of virus infection; however, the reduction in CD13 poly A+ RNA levels was much less pronounced. This differential effect suggests that HCMV may be downregulating expression of CD10 and CD13 by independent mechanisms. Indeed, treatment of cells with an inhibitor of viral DNA synthesis blocks downregulation of CD13, whilst downregulation of CD10 is unaffected. While it is not yet clear what advantage is bestowed on the virus by downregulating expression of CD13 and CD10, aminopeptidases are known to have a role in peptide processing in both the MHC class I the MHC class II antigen presentation pathways.

Traumatic posterior fossa extradural haematomas (PFEDH)

OBJECTIVES

While posterior fossa extradural haematomas (PFEDH) may lead to rapid neurological deterioration and death because of brainstem compression, prompt treatment often leads to a good outcome. The non-specific clinical signs and the rarity of this lesion in craniocerebral trauma adds to the difficulty in diagnosis. The aim of this study was to identify features which could lead to an early diagnosis.

METHODS

Seventeen patients with posterior fossa extradural haematomas were operated on over 4 1/2 years, accounting for 7.5% of the 226 surgically operated extradural haematomas in the Department of Neurosurgery, Tan Tock Seng Hospital, Singapore. Four patients were excluded from this study due to non-availability of the case records. The remaining 13 patients formed the study group in this retrospective analysis.

RESULTS

The majority of cases (77%) presented acutely within 24 hours. The mechanism of injury varied from a fall in 7 cases, a road traffic accident in 4 cases and assault in 2. Nine patients had evidence of external injury to the occiput, 8 patients had skull fractures, and diastasis of the lambdoid suture was seen in 2 cases. Presence of aerocele was noted in the CT scan of 4 cases. All 9 cases admitted with a high GCS score of more than 8 had a very good outcome.

CONCLUSION

An early CT scan head is recommended if a combination of the following features is present: occipital soft tissue injury, drowsiness, occipital fracture or diastasis of the lambdoid suture.

Role of the CCAAT/enhancer binding protein-alpha transcription factor in the glucocorticoid stimulation of p21waf1/cip1 gene promoter activity in growth-arrested rat hepatoma cells

The preceding paper (Cha, H. H., Cram, E. J., Wang, E. C., Huang, A. J., Kasler, H. G., and Firestone, G. L. (1998) J. Biol. Chem. 273, 0000-0000(478563) defined a glucocorticoid responsive region within teh promoter of the p21 CDK inhibitor gene that contains a putative DNA-binding site for the transcription factor CCAAT/ enhancer binding protein-alpha (C/EBP alpha). Wild type rat BDS1 hepatoma cells as well as as4 hepatoma cells, which express antisense sequences to C/EBP alpha and ablate its protein production, were utilized to investigate the role of this transcription factor in the glucocorticoid regulation of p21 gene expression. The stimulation of p21 protein levels and promoter activity, as well as inhibition of CDK2-mediated retinoblastoma protein phosphorylation, by the synthetic glucocorticoid, dexamethasone, required the expression of C/EBP alpha. Overexpression of C/EBP alpha in as4 cells rescued the dexamethasone responsiveness of the p21 promoter. Site-directed mutagenesis of the p21 promoter revealed that dexamethasone stimulation of p21 promoter activity required the C/EBP consensus DNA-binding site. Furthermore, in glucocorticoid receptor-defective EDR1 hepatoma cells, dexamethasone failed to stimulate C/EBP alpha and p21 protein expression and promoter activities. Our results have established a functional link between the glucocorticoid receptor signaling pathway that mediates a G1 cell cycle arrest of rat hepatoma cells and the transcriptional control of p21 by a cascade that requires the steroid induction of C/EBP alpha gene expression.

Glucocorticoids stimulate p21 gene expression by targeting multiple transcriptional elements within a steroid responsive region of the p21waf1/cip1 promoter in rat hepatoma cells

Glucocorticoids can induce a G1 arrest in the cell cycle progression of BDS1 rat hepatoma cells. In these cells, dexamethasone, a synthetic glucocorticoid, stimulated a rapid and selective increase in expression of the p21 cyclin-dependent kinase (CDK) inhibitor mRNA and protein and virtually abolished CDK2 phosphorylation of the retinoblastoma protein. Expression of the p27 CDK inhibitor, and other G1-acting cell cycle proteins, remained unaffected. Dexamethasone stimulated p21 promoter activity in a p53-independent manner that required functional glucocorticoid receptors. Transforming growth factor-beta, which also induced a G1 cell cycle arrest of the hepatoma cells, failed to elicit this response. Analysis of 5' deletions of the p21 promoter uncovered a glucocorticoid responsive region between nucleotides -1481 and -1184, which does not contain a canonical glucocorticoid response element but which can confer dexamethasone responsiveness to a heterologous promoter. Fine mapping of this region uncovered three distinct 50-60-base pair transcriptional elements that likely function as targets of glucocorticoid receptor signaling. Finally, ectopic expression of p21 had no effect on hepatoma cell growth in the absence of glucocorticoids but facilitated the ability of dexamethasone to inhibit cell proliferation. Thus, our results have established a direct transcriptional link between glucocorticoid receptor signaling and the regulated promoter activity of a CDK inhibitor gene that is involved in the cell cycle arrest of hepatoma cells.

A longitudinal study of immunological status in Chinese haemophiliacs: importance of the heat viral inactivation of factor concentrates. II. Improvements of CD4/CD8 ratio after treatments with heat-inactivated factor concentrates

Screened and heated clotting factor concentrates of intermediate purity have been used in Taiwanese haemophiliacs since the end of 1986. A significant improvement of CD4/CD8 ratio during the years 1987-1989 as compared with those during the years 1984-1986 was observed in haemophilia A patients [mean +/- SD (median), 1.191 +/- 0.495 (1.163) vs. 0.880 +/- 0.325 (0.838), P = 0.0020] who were seronegative for human immunodeficiency virus. Almost all patients received an increased amount of factor VIII concentrates and total plasma products since 1987. Multiple linear regression analysis for the association of CD4/CD8 ratio with changes in dosage of plasma products revealed that there was a significant positive association of CD4/CD8 ratio measured during 1987-1989 with dosage of factor VIII concentrate administered during 1984-1986 (P = 0.0230), which is an indicator for changes in viral load, but not with changes in dosage of plasma products, which are indicators for changes in plasma protein intake. Our data indicate that immunological abnormalities after replacement therapy observed in haemophiliacs are mainly attributed to virus infection through infusion of factor concentrates, not to allogeneic proteins existing in plasma products.

Consequences of live poliovirus vaccine administration in chronic fatigue syndrome

The effect of live oral polio virus vaccination on chronic fatigue syndrome (CFS) patients was examined in a double-blind study. CFS patients were allocated randomly to placebo (N = 7) or vaccine (N = 7) conditions. All controls subjects received the vaccine (9). Vaccine administration was not associated with clinical exacerbation of CFS. However, objective responses to the vaccine revealed differences between patients and controls: increased poliovirus isolation, earlier peak proliferative responses, lower T-cell subsets on certain days post vaccination and a trend for reduced gamma-interferon in the CFS-vaccine group. Polio vaccination was not found to be clinically contraindicated in CFS patients, however, there was evidence of altered immune reactivity and virus clearance.

The role of the Cys191-Cys220 disulfide bond in trypsin: new targets for engineering substrate specificity

The S1 binding site of trypsin is cross-linked by the conserved Cys191-Cys220 disulfide bond. The substitution of Cys191 and Cys220 with Ala decreases the activity of trypsin by 20-200-fold as measured by kcat/K(m) for the hydrolysis of amide substrates; in contrast, ester hydrolysis is decreased by < 10-fold. Similar decreases are observed in the hydrolysis of oligopeptide and single amino acid substrates. This decrease in activity results from a decrease in the acylation rate. The substrate binding and deacylation rate are not affected by the loss of the disulfide bond. C191A/C220A binds BPTI with the same affinity as trypsin, although the affinity of benzamidine is decreased 10-fold and the affinity of leupeptin is decreased 1000-fold. The CD spectrum of C191A/C220A displays significant differences from that of trypsin; these differences most likely result from the loss of the disulfide chromophore, although perturbation of enzyme structure cannot be discounted. The loss of the Cys191-Cys220 disulfide has no effect on the stability of trypsin as measured by urea denaturation. Single and double substitutions of Ser at positions 191 and 220 have a similar activity to C191A/C220A. These results indicate that the Cys191-Cys220 disulfide bond is not essential for the function, structure or stability of trypsin.

CD8high+ (CD57+) T cells in patients with rheumatoid arthritis

OBJECTIVE

To investigate the development and T cell receptor (TCR) usage of CD8+, CD57+ T cells in rheumatoid arthritis (RA) patients.

METHODS

Three-color flow cytometry using monoclonal antibodies (MAb) to CD8, CD57 and different TCR V beta gene products.

RESULTS

The proportion of CD8+ T cells expressing CD57 (CD57/CD8) was significantly higher in RA patients compared with age-matched controls. Expanded TCR V beta populations were more frequent, and were found in both RA patient-derived CD8high+ (CD57+) and CD8+, CD57- populations. TCR V beta 5+ and TCR V beta 13+ expansions were present at high frequency (5 of 26 and 7 of 26, respectively). TCR V beta expansions in CD8high+ (CD57+) lymphocytes from RA patients were significantly larger than those in age-matched controls (expansion index 2.38 +/- 0.28, n = 41 and 1.63 +/- 0.09, n = 32, respectively), and were stable over time.

CONCLUSION

RA leads to an increase in the frequency of expanded CD8+ T cell subsets expressing selected TCR, due to expansion of TCR V beta + populations in CD8high+ (CD57+) T cells. Their restricted TCR usage suggests potential specificity for RA antigens and, therefore, a potential role in the pathogenesis of RA.

CD8highCD57+ T lymphocytes in normal, healthy individuals are oligoclonal and respond to human cytomegalovirus

CD8+CD57+ lymphocytes from normal peripheral blood are divided into T cells expressing high levels of CD8 and NK cells expressing low levels of surface CD8. Increased numbers of CD8highCD57+ T cells correlate with previous exposure to human cytomegalovirus (HCMV) infection, but no virus-specific function or function for CD8highCD57+ cells has been recorded. We have studied the TCR repertoire and responses of the CD8highCD57+ population induced by virus-infected fibroblasts in healthy individuals. Using three-color flow cytometry of PBL, we detected restricted TCRBV usage in the CD8highCD57+ subset of 11/15 subjects, compared with 1/15 in the CD8+, CD57- subset. The results of anchored PCR and sequencing also showed oligoclonality of TCR; 40-70% of CD8highCD57+ lymphocytes (10-20% of total CD8+ T cells) were derived from single clones. Such expansions were stable with time and detected in one subject over a 2-yr period. Functionally, CD8highCD57+ lymphocytes proliferated strongly to HCMV-, but not HSV-, VZV-, or influenza-infected fibroblasts in an MHC-unrestricted manner in vitro, including preferential augmentation of particular in vivo oligoclonally expanded subpopulations. HCMV-specific MHC-restricted CTL were detected, but limiting dilution analysis showed that these were a minority (< 10%) and not the oligoclonal subsets. In contrast, depletion of oligoclonally expanded CD8highCD57+ subpopulations, resulted in the increase of HCMV-specific CTL, suggesting functional heterogeneity in these cells.

CD8highCD57+ T lymphocytes in normal, healthy individuals are oligoclonal and respond to human cytomegalovirus

CD8+CD57+ lymphocytes from normal peripheral blood are divided into T cells expressing high levels of CD8 and NK cells expressing low levels of surface CD8. Increased numbers of CD8highCD57+ T cells correlate with previous exposure to human cytomegalovirus (HCMV) infection, but no virus-specific function or function for CD8highCD57+ cells has been recorded. We have studied the TCR repertoire and responses of the CD8highCD57+ population induced by virus-infected fibroblasts in healthy individuals. Using three-color flow cytometry of PBL, we detected restricted TCRBV usage in the CD8highCD57+ subset of 11/15 subjects, compared with 1/15 in the CD8+, CD57- subset. The results of anchored PCR and sequencing also showed oligoclonality of TCR; 40-70% of CD8highCD57+ lymphocytes (10-20% of total CD8+ T cells) were derived from single clones. Such expansions were stable with time and detected in one subject over a 2-yr period. Functionally, CD8highCD57+ lymphocytes proliferated strongly to HCMV-, but not HSV-, VZV-, or influenza-infected fibroblasts in an MHC-unrestricted manner in vitro, including preferential augmentation of particular in vivo oligoclonally expanded subpopulations. HCMV-specific MHC-restricted CTL were detected, but limiting dilution analysis showed that these were a minority (&lt; 10%) and not the oligoclonal subsets. In contrast, depletion of oligoclonally expanded CD8highCD57+ subpopulations, resulted in the increase of HCMV-specific CTL, suggesting functional heterogeneity in these cells.

Human HLA-A0201-restricted cytotoxic T lymphocyte recognition of influenza A is dominated by T cells bearing the V beta 17 gene segment

The major histocompatibility complex class I-restricted cytotoxic T lymphocyte (CTL) response is important in the clearance of viral infections in humans. After influenza A infection, a peptide from the matrix protein, M58-66, is presented in the context of the MHC allele HLA-A0201 and the resulting CTL response is detectable in most HLA-A0201 subjects. An initial study suggested that M58-66-specific CTL clones show conserved T cell receptor (TCR) alpha and beta gene segments. We have addressed the significance of this observation by determining the expression of V beta 17 during the development of M58-66-specific CTL lines in 21 unrelated HLA-A0201 subjects, and analyzing TCR usage by M58-66-specific CTL clones. TCR V beta 17 was the dominant V beta segment used and CD8 V beta 17 expansion correlated with M58-66-specific lysis. Limiting dilution analysis from five subjects showed the M58-66 CTL precursor frequency to vary between 1/54,000 and less than 1/250,000, and that up to 85% of the matrix peptide (M58-66)-specific CTL used the V beta 17 gene segment. The M58-66 specific CTL response was dependent on previous viral exposure and specific V beta 17 expansion, as it was not found in cord blood, despite a readily expandable V beta 17+ CD8+ T cell subpopulation. Sequence analysis of 38 M58-66-specific V beta 17 transcripts from 13 subjects revealed extensive conservation in the CDR3 region including conservation of an arginine-serine motif. To test the dependence of this CTL response on the V beta 17 gene segment, peripheral blood lymphocytes were depleted of CD8+ TCR V beta 17+ cells, before the generation of M58-66-specific CTL. In most cases such depletion blocked or severely reduced the generation of the M58-66-specific response, and under limiting dilution conditions could abolish M58-66-specific CTL precursors. These studies reveal the dependence of this natural human immune response on a particular TCR gene segment.

CD8high (CD57+) T cells in normal, healthy individuals specifically suppress the generation of cytotoxic T lymphocytes to Epstein-Barr virus-transformed B cell lines

We have previously identified two subsets of CD8+, CD57+ lymphocytes in normal peripheral blood: i) T cells expressing high levels [CD8high(CD57+)] and ii) natural killer cells expressing low levels of surface CD8[CD8low(CD57+)]. We investigated the cytotoxic and suppressive function of CD8high(CD57+) T lymphocytes from normal, healthy individuals using standard chromium-release assays and limiting dilution analysis. In normal, healthy subjects, this cell subset suppressed the generation of cytotoxic T lymphocytes (CTL) to autologous, Epstein-Barr virus (EBV)-transformed B cell lines (BCL). Depletion of CD8high(CD57+) T lymphocytes from peripheral blood mononuclear cells (PBMC) resulted in a three- to sevenfold rise in CTL precursor frequency to autologous EBV-transformed BCL, but not allogeneic PBMC or BCL by LDA. Replacement of CD8high(CD57+) T lymphocytes in limiting dilution cultures led to the dose-dependent suppression of EBV-specific, but not allogeneic, CTL generation. Supernatant from CD8high(CD57+) T lymphocytes cultured with autologous BCL did not exhibit suppression, suggesting that soluble factors were not responsible. As CD8high(CD57+) T lymphocytes did not, themselves, exhibit cytotoxicity against autologous BCL, removal of BCL stimulator cells in co-culture was not the mechanism of suppression. Furthermore, while the CD8high(CD57+) T lymphocytes from healthy subjects suppressed the generation of CTL to autologous BCL, they did not suppress the cytotoxic activity of established mixed lymphocyte reactions or peptide-specific CTL clones, as has been reported in bone marrow transplant recipients and human immunodeficiency virus patients. This suggests that CD8high(CD57+) T lymphocytes from healthy subjects suppress the generation of, rather than killing by, CTL in a contact-dependent manner. To our knowledge, this is the first identification of a phenotypically distinct subset of human CD8+ T cells that can suppress generation of antigen-specific major histocompatibility complex class I-restricted CTL.

Incidence of postoperative epilepsy in children following subfrontal craniotomy for tumor

Thirty-one children who underwent 36 subfrontal craniotomies were retrospectively studied to determine the incidence of postoperative epilepsy and the effectiveness of antiepileptic drugs for seizure prophylaxis. The incidence of postoperative epilepsy following a subfrontal craniotomy did not exceed 12% when examined at various time periods during a 3-year postoperative course. Antiepileptic drugs were not warranted to reduce the incidence of postoperative seizures after the 1-month postoperative period and should not be used for long-term prophylactic therapy in children following a subfrontal craniotomy.

Subsets of CD8+, CD57+ cells in normal, healthy individuals: correlations with human cytomegalovirus (HCMV) carrier status, phenotypic and functional analyses

Two different subsets of CD8+, CD57+ cells have been defined, one expressing high levels (CD8high+(CD57+)), the other expressing low levels of surface CD8 (CD8low+(CD57+)). Increased numbers of CD8high+(CD57+) cells correlated with previous HCMV infection. By three-colour fluorescence analysis, the CD8high+(CD57+) population expressed T cell markers such as CD3 and CD5, and most were alpha beta T cell receptor (alpha beta TCR)-positive. A significant proportion also expressed CD71 (transferrin receptor) and MHC class I, although little if any CD25 (IL-2R-p55). Some (> or = 40%) co-expressed CD45RA and CD45RO. The CD8low+(CD57+) population expressed classical natural killer (NK) cell markers--CD2, CD16 and CD56. The two subsets were also functionally distinct; CD8high+(CD57+) cells suppressed pokeweed mitogen (PWM)-driven, but not phytohaemagglutinin (PHA)-driven proliferation and immunoglobulin production; CD8low+(CD57+) cells exhibited NK cytotoxic activity which was not increased by interferon-alpha (IFN-alpha). Supernatant from cultured CD8high+(CD57+) cells suppressed PWM-driven immunoglobulin production, but not proliferation, and this effect was abrogated by physical separation with tissue culture inserts. Thus, a T cell subset expressing activation and memory T cell markers with direct non-specific suppressor activity was present in peripheral blood mononuclear cells (PBMC) of healthy subjects with asymptomatic HCMV infection.

5-Benzylbarbituric acid derivatives, potent and specific inhibitors of uridine phosphorylase

5-Benzylbarbituric acid derivatives were synthesized as a series of new, specific, and potent inhibitors of uridine phosphorylase. Among these, 5-(m-benzyloxy)benzyl-1-[(2-hydroxyethoxy)methyl] barbituric acid (5-benzyloxybenzylbarbituric acid acyclonucleoside, BBBA) was found to be the most potent with Ki values of 1.1 +/- 0.2 and 2.6 +/- 0.3 nM with uridine phosphorylase from human and mouse livers, respectively. BBBA exhibited competitive inhibition with uridine phosphorylase from both human and mouse livers. The 5-benzylbarbituric acid derivatives are specific inhibitors of uridine phosphorylase, as they had no effect on thymidine phosphorylase (EC 2.4.2.4), thymidine kinase (EC 2.7.1.21), uridine-cytidine kinase (EC 2.7.1.48), orotate phosphoribosyltransferase (EC 2.4.2.10), orotidine 5'-monophosphate decarboxylase (EC 4.1.2.23), and dihydrouracil dehydrogenase (EC 1.3.1.2). These compounds are more potent, easier to synthesize, and have better water solubility than their uracil counterparts as inhibitors of uridine phosphorylase. Furthermore, the 5-benzylbarbituric acids were found to be better inhibitors of human uridine phosphorylase than the murine enzyme, whereas the reverse holds true for the 5-benzyluracil derivatives. The 5-benzylbarbituric acid derivatives have potential usefulness in the therapy of cancer and AIDS, as well as other pathological and physiological disorders.

Analysis of the human T-cell response to picornaviruses: identification of T-cell epitopes close to B-cell epitopes in poliovirus

Little is known about the nature and specificity of T-cell-mediated responses to picornaviruses in humans. In this study, the nature of the T-cell response to seven picornaviruses, including polioviruses, coxsackieviruses B3 and B4, human rhinovirus 14, and encephalomyocarditis virus, was determined. Twenty-nine individuals responded to poliovirus type 3, coxsackievirus B3, and encephalomyocarditis virus by proliferation of T cells, and from such cultures, 130 virus-specific T-cell lines were established. T-cell lines generated in response to encephalomyocarditis virus were exclusively strain specific. However, the majority of T-cell lines established in response to viruses, other than encephalomyocarditis virus, were cross-reactive to each other. Their cross-reactivity was confirmed in 2 of the 30 picornavirus-specific clonally derived T-cell lines from two subjects, but the majority of these lines were serotype specific. T-cell epitopes adjacent to each of the B-cell antigenic sites in VP1 of poliovirus type 3 were identified. The response to the region adjacent to B-cell antigenic site 1 (residues 97 to 114) was dominant between individuals. The localization of this major CD4 T-cell epitope may permit the construction of chimeric viruses utilizing the natural picornavirus T-cell response to augment production of antibody specific for inserted sequences.