Power analysis for idiographic (within-subject) clinical trials: Implications for treatments of rare conditions and precision medicine

Power analysis informs a priori planning of behavioral and medical research, including for randomized clinical trials that are nomothetic (i.e., studies designed to infer results to the general population based on interindividual variabilities). Far fewer investigations and resources are available for power analysis of clinical trials that follow an idiographic approach, which emphasizes intraindividual variabilities between baseline (control) phase versus one or more treatment phases. We tested the impact on statistical power to detect treatment outcomes of four idiographic trial design factors that are under researchers' control, assuming a multiple baseline design: sample size, number of observations per participant, proportion of observations in the baseline phase, and competing statistical models (i.e., hierarchical modeling versus piecewise regression). We also tested the impact of four factors that are largely outside of researchers' control: population size, proportion of intraindividual variability due to residual error, treatment effect size, and form of outcomes during the treatment phase (phase jump versus gradual change). Monte Carlo simulations using all combinations of the factors were sampled with replacement from finite populations of 200, 1750, and 3500 participants. Analyses characterized the unique relative impact of each factor individually and all two-factor combinations, holding all others constant. Each factor impacted power, with the greatest impact being from larger treatment effect sizes, followed respectively by more observations per participant, larger samples, less residual variance, and the unexpected improvement in power associated with assigning closer to 50% of observations to the baseline phase. This study's techniques and R package better enable a priori rigorous design of idiographic clinical trials for rare diseases, precision medicine, and other small-sample studies.

Addition of Metastasis-Directed Therapy to Standard of Care Systemic Therapy for Oligometastatic Breast Cancer (EXTEND): A Multicenter, Randomized Phase II Trial

PURPOSE/OBJECTIVE(S)

Prior retrospective and prospective evidence have suggested a potential survival benefit of adding metastasis-directed therapy (MDT) to standard of care systemic therapy for oligometastatic breast cancer. This has led to the increased utilization of MDT in this setting despite the lack of randomized evidence to support this approach. Furthermore, the recent presentation of NRG-BR002 has questioned the value of MDT. Thus, we evaluated whether the addition of MDT to systemic therapy improves PFS in oligometastatic breast cancer.

MATERIALS/METHODS

EXTEND (NCT03599765) is a phase II randomized basket trial for multiple solid tumors testing whether the addition of MDT improves PFS. The primary endpoint was pre-specified to be independently assessed and reported for the breast basket when a minimum of 6 months of follow-up had been reached. Patients with ≤5 metastases were randomized to standard of care systemic therapy with or without MDT. The choice of systemic therapy was at the discretion of the treating medical oncologist. Number of metastatic lesions and prior lines of systemic therapy for metastatic disease were used as stratification variables pre-randomization. The primary endpoint was progression-free survival (PFS) defined as time to randomization to date of clinical or radiographic progression or death. The study was designed to have 80% power to detect an improvement in median PFS from 18 to 36 months, with a type I error of 0.1.

RESULTS

Between September 2018 to July 2022, 43 patients were randomized. 22 patients were assigned to the MDT arm, and 21 patients to the no MDT arm. Three patients were not evaluable. The MDT arm patients were older vs the no-MDT arm patients (median 61.5 years vs 48 years, p = 0.01). Otherwise, the arms were well-balanced. Overall, 8 patients had triple negative disease (18.6%), and 12 patients (30%) had de novo metastatic disease. Of those patients with de novo presentation randomized to MDT, all except one had the primary tumor treated with surgery and radiation. At a median follow-up of 19.4 months, 20 events were observed. Among the 40 evaluable patients, there were 5 deaths (3 in the MDT arm and 2 in the no MDT arm). There was no difference in PFS between the MDT and no MDT arms (median 15.6 v 24.9 months, p = 0.66). Similarly, there was no difference in the secondary endpoint of time to new metastatic lesion appearance between the MDT and no MDT arms (median 15.6 months vs not reached, p = 0.09). Two grade 3 toxicities were observed in the MDT arm, and 1 in the no MDT arm. Further analysis of correlative translational biomarkers, including immune markers and ctDNA, are ongoing.

CONCLUSION

The addition of MDT to standard of care systemic therapy did not improve PFS or time to new metastatic lesion in patients with oligometastatic breast cancer. This data coupled with the recently presented NRG-BR002 results, suggests there is no benefit to MDT in an otherwise unselected oligometastatic breast cancer population.

Use of Mobile Technology Paired with Heart Rate Monitor to Remotely Quantify Behavioral Health Markers among Military Reservists and First Responders

INTRODUCTION

Heart rate variability (HRV) is a biological marker that reflects an individual's autonomic nervous system regulation. Psychological resilience is an individual's ability to recover from an adverse event and return to physiological homeostasis and mental well-being, indicated by higher resting HRV. The Biofeedback Assisted Resilience Training (BART) study evaluates a resilience-building intervention, with or without HRV biofeedback. This article evaluates the feasibility of remote psychophysiological research by validating the HRV data collected.

MATERIALS AND METHODS

The BART platform consists of a mobile health application (BART app) paired to a wearable heart rate monitor. The BART app is installed on the participant's personal phone/tablet to track and collect self-report psychological and physiological data. The platform collects raw heart rate data and processes HRV to server as online biofeedback. The raw data is processed offline to derive HRV for statistical analysis. The following HRV parameters are validated: inter-beat interval, respiratory sinus arrhythmia, low-frequency HRV, biofeedback HRV, and heart period. Bland-Altman and scatter plots are used to compare and contrast online and offline HRV measures. Repeated-measures ANOVA are used to compared means across tasks during the stress (rest, stress, and recovery) and training (rest and paced breathing) sessions in order to validate autonomic nervous system changes to physiological challenges.

RESULTS

The analyses included 245 participants. Bland-Altman plots showed excellent agreement and minimal bias between online and offline unedited inter-beat interval data during the stress session. RMANOVA during the training session indicated a significant strong effect on biofeedback HRV, F(11,390) = 967.96, P < .01. During the stress session, RMANOVA showed significant strong effect on respiratory sinus arrhythmia and low-frequency HRV, and a significant but weak effect on heart period.

CONCLUSIONS

The BART digital health platform supports remote behavioral and physiological data collection, intervention delivery, and online HRV biofeedback.

The effect of hybrid zinc oxide/graphene oxide (ZnO/GO) nano-catalysts on the photocatalytic degradation of simazine

The photocatalytic degradation of simazine (SIM) was investigated using zinc oxide/graphene oxide (ZnO/GO) composite materials under visible light irradiation. The reaction kinetics was studied to optimize the reaction parameters for efficient degradation of SIM. Batch studies were performed to investigate the effects of initial reaction pH, the loading of the ZnO onto GO, and mass of catalyst on the removal of SIM from aqueous solution. A pH of 2 was determined to be the optimal reaction pH for the different ZnO-loaded GO catalysts. In addition, a mass of 40 mg of catalyst in the reaction was observed to be the most effective for the catalysts synthesized using 20 and 30 mmol of Zn²⁺ ions; whereas a mass of 10 mg was most effective for the ZnO/GO composite material synthesized using 10 mmol Zn²⁺ ions. The reaction was observed to follow a second-order kinetics for the degradation process. Furthermore, the synthesized ZnO/GO composite catalysts resulted in higher reaction rates than those observed for pure ZnO. The 30 mmol ZnO/GO composite expressed a rate of SIM degradation ten times greater than the rate observed for pure ZnO, and sixty-two times greater than the rate of photolysis. In addition, the catalyst cycling exhibited a constant photocatalytic activity for the ZnO/GO composite over three reaction cycles without the need of a conditioning cycle.

P506Brugada Syndrome: is the addition of the electrocardiographic risk markers the clue?

Background

Risk stratification in Brugada Syndrome (BS) remains a clinical challenge. Several electrocardiografic (ECG) risk markers had been described, as a spontaneous type 1 Brugada pattern (ST1B), maximal time interval between the peak and the end of the t wave in precordial leads (Tpe Max), the presence of an S Wave on DI, a PR interval (PRi) ≥ 200ms and fragmented QRS (f-QRS).

Purpose

Evaluate the association of ECG risk markers with sudden cardiac death (SCD) or appropriate shocks (A-Sh) by implantable cardioverter defibrillator (ICD) in patients (p) with BS.

Methods

From a registry of 97 p with BS with a median follow up of 2.3 years (Q1 0.7-Q3 7.8), 12 lead ECG were recorded in every p. QT peak interval (QTp) was measured between the QRS onset and the peak of the T wave. Tpe was calculated between the difference of QT and QTp in precordial leads (V1 to V6). TpeMax was defined as the most prolonged Tpe. If an S-DI was present, duration and amplitude was measured. PRi was measured on DII. Baseline characteristics: Age 44 ± 13 years, male 74 (76%), secondary prevention 2 (3%), malignant syncope 10 (10%), inducible electrophysiology study 22/43 (51%), SCD on first grade family &lt; 35 years 12 (12%) and ICD 34 (35%). A-Sh and SCD were compared among p with ST1B vs no ST1B, TpeMax≥100 vs &lt;100ms, S-DI ≥0.4 vs &lt;0.4ms, S-D ≥0.1 vs &lt;0.1mV, PRi≥200 vs &lt;200ms and presence of f-QRS ≥ 2 spike ≥ 2 leads. Variables that were associated with A-Sh or SCD were combined. For variables with significant difference sensibility (Sen) and specificity (Spe) was calculated.

Results

During follow up 6 p presented A-Sh and no p SCD. Results are described in the Table.

Conclusion

In our study population, there was a significant higher incidence of A-Sh in p with ST1B, Tpe Max ≥ 100ms and S-DI ≥ 0.1mV. We found that the presence of one ECG risk marker had a high sensibility to predict A-Sh. The presence of the 3 ECG risk markers highly increased specificity to predict A-Sh. Further trials should be carried out to asses if ECG risk markers would allow us to differentiate which asymptomatic patients could benefit from electrophysiological study for risk stratification (high sensibility - One ECG Risk marker) or would benefit from ICD implantation (high specificity - 3 ECG Risk markers).

Abstract Figure.

Biofeedback-Assisted Resilience Training for Traumatic and Operational Stress: Preliminary Analysis of a Self-Delivered Digital Health Methodology

Background

Psychological resilience is critical to minimize the health effects of traumatic events. Trauma may induce a chronic state of hyperarousal, resulting in problems such as anxiety, insomnia, or posttraumatic stress disorder. Mind-body practices, such as relaxation breathing and mindfulness meditation, help to reduce arousal and may reduce the likelihood of such psychological distress. To better understand resilience-building practices, we are conducting the Biofeedback-Assisted Resilience Training (BART) study to evaluate whether the practice of slow, paced breathing with or without heart rate variability biofeedback can be effectively learned via a smartphone app to enhance psychological resilience.

Objective

Our objective was to conduct a limited, interim review of user interactions and study data on use of the BART resilience training app and demonstrate analyses of real-time sensor-streaming data.

Methods

We developed the BART app to provide paced breathing resilience training, with or without heart rate variability biofeedback, via a self-managed 6-week protocol. The app receives streaming data from a Bluetooth-linked heart rate sensor and displays heart rate variability biofeedback to indicate movement between calmer and stressful states. To evaluate the app, a population of military personnel, veterans, and civilian first responders used the app for 6 weeks of resilience training. We analyzed app usage and heart rate variability measures during rest, cognitive stress, and paced breathing. Currently released for the BART research study, the BART app is being used to collect self-reported survey and heart rate sensor data for comparative evaluation of paced breathing relaxation training with and without heart rate variability biofeedback.

Results

To date, we have analyzed the results of 328 participants who began using the BART app for 6 weeks of stress relaxation training via a self-managed protocol. Of these, 207 (63.1%) followed the app-directed procedures and completed the training regimen. Our review of adherence to protocol and app-calculated heart rate variability measures indicated that the BART app acquired high-quality data for evaluating self-managed stress relaxation training programs.

Conclusions

The BART app acquired high-quality data for studying changes in psychophysiological stress according to mind-body activity states, including conditions of rest, cognitive stress, and slow, paced breathing.

Diagnostic guidelines for the histological particle algorithm in the periprosthetic neo-synovial tissue

BACKGROUND

The identification of implant wear particles and non-implant related particles and the characterization of the inflammatory responses in the periprosthetic neo-synovial membrane, bone, and the synovial-like interface membrane (SLIM) play an important role for the evaluation of clinical outcome, correlation with radiological and implant retrieval studies, and understanding of the biological pathways contributing to implant failures in joint arthroplasty. The purpose of this study is to present a comprehensive histological particle algorithm (HPA) as a practical guide to particle identification at routine light microscopy examination.

METHODS

The cases used for particle analysis were selected retrospectively from the archives of two institutions and were representative of the implant wear and non-implant related particle spectrum. All particle categories were described according to their size, shape, colour and properties observed at light microscopy, under polarized light, and after histochemical stains when necessary. A unified range of particle size, defined as a measure of length only, is proposed for the wear particles with five classes for polyethylene (PE) particles and four classes for conventional and corrosion metallic particles and ceramic particles.

RESULTS

All implant wear and non-implant related particles were described and illustrated in detail by category. A particle scoring system for the periprosthetic tissue/SLIM is proposed as follows: 1) Wear particle identification at light microscopy with a two-step analysis at low (× 25, × 40, and × 100) and high magnification (× 200 and × 400); 2) Identification of the predominant wear particle type with size determination; 3) The presence of non-implant related endogenous and/or foreign particles. A guide for a comprehensive pathology report is also provided with sections for macroscopic and microscopic description, and diagnosis.

CONCLUSIONS

The HPA should be considered a standard for the histological analysis of periprosthetic neo-synovial membrane, bone, and SLIM. It provides a basic, standardized tool for the identification of implant wear and non-implant related particles at routine light microscopy examination and aims at reducing intra-observer and inter-observer variability to provide a common platform for multicentric implant retrieval/radiological/histological studies and valuable data for the risk assessment of implant performance for regional and national implant registries and government agencies.

Sunitinib, a receptor tyrosine kinase inhibitor, increases blood pressure in rats without associated changes in cardiac structure and function

BACKGROUND

Sunitinib, a multi-tyrosine kinase inhibitor has demonstrated clinical activity in advanced renal cell carcinoma and imatinib-resistant/intolerant gastrointestinal stromal tumor. It has been associated with manageable hypertension and other unique toxicities.

AIMS

Two nonclinical studies were conducted to determine if sunitinib has direct/indirect effects on cardiac structure/function that may be related to hypertension at clinically relevant exposures.

MATERIALS & METHODS

Rats received once-daily vehicle or sunitinib 1 or 10 mg/kg/day (n = 10/group) orally for 4 weeks, followed by 2 weeks off treatment then a 2-week rechallenge. Blood pressure (BP) and heart rate (HR) were continuously acquired and echocardiograms were obtained weekly. Effects of sunitinib and its metabolite (0.003-0.3 μM) were also evaluated in guinea pig isolated Langendorff-perfused hearts (n = 4-6 hearts/group).

RESULTS

Sunitinib 10 mg/kg/day produced significant (P < 0.05) hemodynamic changes: 24 h average BP increased during initial dosing/rechallenge, with rebound hypotension during the off-treatment period; 24 h average HR increased during the off-treatment period, and decreased during rechallenge; no changes in cardiac structure/function were observed. In guinea pig isolated hearts, neither sunitinib nor its metabolite had direct effects on contractility, HR or left ventricular pressure.

DISCUSSION & CONCLUSION

These studies demonstrate that sunitinib/metabolite had no direct effects on cardiac function ex vivo, and that therapeutically relevant concentrations of sunitinib dosed on a "clinical schedule" increased BP in rats without adverse changes in cardiac structure/function.

Semi-continuous biohydrogen production as an approach to generate electricity

In this work, a semi-continuous biological system was established to produce hydrogen and generate electricity by coupling the bioreactor to a fuel cell. Heat and acid pretreatments (at 35 and 55 degrees C) of a seed sludge used as inoculum were performed in order to increase hydrogen producers. Different initial glucose concentrations (IGC) were tested for heat pretreated inoculum at 35 degrees C to determine the optimum concentration of glucose that supported the highest hydrogen production. Results showed that the heat pretreated inoculums (35 degrees C) reached the highest hydrogen molar yield of 2.85 mol H(2)/mol glucose (0.014 L/h), which corresponds to the acetic acid pathway. At the optimum IGC (10 g/L, 35 degrees C) the hydrogen molar yield was 3.6 mol H(2)/mol glucose (0.023 L/h). The coupled bioreactor-fuel cell system yielded an output voltage of 1.06 V, power of 0.1 W (25 degrees C) and a current of 68 mA. The overall results suggest that high hydrogen molar yields can be obtained through the acetic acid pathway and that is feasible to generate electricity using hydrogen from the semi-continuous bioreactor.

Genetic structure of the genera Psorophora (Diptera: Culicidae) in Columbian and North American populations using isoenzymes and ITS2 sequences

Two, a priori, Psorophora columbiae and one, a priori, Ps. toltecum populations from Colombia were studied by means of eleven isoenzyme loci. The levels of genetic diversity, Hardy-Weinberg equilibrium, gene flow estimates, isolation by distance and genetic relationships among these three populations were studied and the results were as follows: 1. The gene diversity levels were high as well as very similar among the three populations indicating no differences between them. 2. Within each population and from a hierarchical standpoint several loci were not in Hardy-Weinberg equilibrium simultaneously by excess and defect of heterozygous. This could reflect that several natural selection forces are acting upon these mosquito populations. 3. The gene flow estimate for these populations showed the existence of this event between them. This agrees quite well with the fact that the three populations really belong to a single species. In addition, maximum parsimony analyses with 16 isoenzyme for several individuals from four Colombian and two United States Psorophora populations showed that effectively only one species was present in the Colombian area surveyed, and that this species is Ps. columbiae, which hardly contrast with that previously suggested by other authors.

Identification of a peptide that protects the human acetylcholine receptor against antigenic modulation

mAb 192 is a rat monoclonal antibody with very high affinity for the major immunogenic region (MIR) of the human muscle acetylcholine receptor (AChR). An epitope mimic of this antibody was selected from a phage display peptide library screened with mAb 192. The peptide-presenting phage has been shown to specifically bind to solid phase mAb 192 with an equilibrium dissociation constant (K(d)) of 8.45x10(-9) M, as directly measured with surface plasmon resonance. This value represents the avidity of the interaction between selected phage and mAb 192. A synthetic version of this peptide QPSPYNGWRMEI, referred to as MG15, binds to its selecting antibody and blocks the interaction of mAb 192 with human AChR. Peptide MG15 was able to protect acetylcholine receptors on human RD cells from antibody-mediated down-modulation. The negative charge of glutamic acid plays a important role in antibody binding. Replacement of the glutamic acid with an alanine completely abolishes the inhibitory activity.

Epidermal growth factor reduces multiorgan failure induced by thioacetamide

BACKGROUND

Multiorgan failure is a severe life threatening state where present therapeutic approaches are suboptimal. Epidermal growth factor (EGF) is a potent stimulant of repair in in vitro and in vivo models. We therefore examined its potential beneficial effect in reducing mortality and injury induced by the noxious agent thioacetamide (TAA).

METHODS

Mice (20 per group) were fasted overnight and received a single intraperitoneal dose of human recombinant EGF at 10 or 30 microg/kg or saline (control). Either 30 minutes before or after EGF, all animals also received TAA (40 mg/kg intraperitoneally). Twenty four hours later, surviving animals were killed, tissues collected, and degree of organ injury assessed.

RESULTS

Fifty per cent (10/20) of control animals died within the first 24 hour period. Mortality was almost completely prevented by the higher dose of EGF whether given before or after TAA (p<0.01) and was reduced by about 50% with the lower dose of EGF. In control animals, the entire length of the jejunum and ileum had necrosis with or without mucosal denudation. In contrast, necrosis affected only about 10-20% of the total length in EGF treated groups (both p<0.01 v control). Control animals showed marked glomerular tuft collapse, interstitial haemorrhage, and increased plasma creatinine levels. These effects were significantly reduced in animals given EGF (30 microg/kg; p<0.01). All groups showed similar changes in liver histology (centrilobular necrosis) and alanine transaminase levels (10-fold increase).

CONCLUSIONS

Although EGF did not prevent the hepatotoxicity associated with TAA, it reduced mortality, renal injury, and gastrointestinal damage. These studies provide preliminary evidence that EGF may be a novel approach for the prevention and/or treatment of multiorgan failure.

Visual evoked potentials related to motion-onset are modulated by attention

The effects of attention on visual evoked potentials triggered by motion-onset were examined in four experiments. A set of randomly oriented bars was used as stimuli. The first experiment showed that responses to motion-onset following pattern-onset by less than 300 ms were suppressed. In the other three experiments, the amplitude of N170 was reduced when attention was drawn away from the moving elements and towards spatially interspersed bars that remained static. The superposition of the two sets made spatial selection unlikely. These results support the existence of an attentional 'motion filter' (separating stationary from moving elements) that can operate at early stages of visual processing.

Giardia lamblia: incorporation of free and conjugated fatty acids into glycerol-based phospholipids

Giardia lamblia trophozoites are flagellated protozoa that inhabit the human small intestine, where they are exposed to various dietary lipids and fatty acids. It is believed that G. lamblia, which colonizes a lipid-rich environment of the human small intestine, is unable to synthesize phospholipids, long-chain fatty acids, and sterols de novo. Therefore, it is possible that this protozoan has developed a special process for acquiring lipids from its host. We have previously shown that G. lamblia can take up saturated fatty acids and incorporate them into phosphatidylglycerol (PG) and other glycerol-based phospholipids (Stevens et al., Experimental Parasitology, 86, 133-143, 1997). In the present study, an attempt has been made to investigate the underlying mechanisms of transesterification and interesterification reactions of giardial phospholipids by free and conjugated fatty acids. Results show that exogenously supplied, unsaturated, fatty acids were taken up by Giardia and incorporated into various phosphoglycerides, including PG. To test whether this intestinal pathogen can utilize conjugated fatty acids, live trophozoites were exposed to either [3]H;cbphosphatidylcholine (PC), where the fatty acid was 3H-labeled at its sn2 position, or to [14C]lyso-PC (fatty acid was 14C-labeled at the sn1 position) for 90 min, followed by phospholipid analysis using thin-layer chromatography. The results suggest that conjugated fatty acids, like free fatty acids, were incorporated into PG. It was also observed that aristolochic acid, an inhibitor of Ca2+-ionophore-stimulated phospholipase A2, decreased the transfer of fatty acids from [3H]PC to PG, indicating that giardial phospholipases were involved in these esterification reactions. Additional experiments, which include culturing trophozoites in serum-supplemented and serum-deprived medium, along with numerous biochemical analyses suggest that (i) PG is a major transesterified and interesterified product, (ii) it is likely that giardial phospholipases are involved in esterification reactions, (iii) in G. lamblia, PG is localized in perinuclear membranes, as well as intracellularly, but not in the plasma membrane, and (iv) various synthetic analogs of PG inhibit the growth of the parasite in vitro. These studies suggest that PG is an important phospholipid of Giardia and a potential target for lipid-based chemotherapy against giardiasis.

CD86 (B7-2), but not CD80 (B7-1), expression in the epidermis of transgenic mice enhances the immunogenicity of primary cutaneous Candida albicans infections

Transgenic (Tg) mice whose epidermal keratinocytes constitutively overexpress either B7-1 (CD80) or B7-2 (CD86) exhibited exaggerated cutaneous delayed type hypersensitivity (DTH) to haptens compared to non-Tg mice. To determine whether enhanced DTH in these Tg mice is seen in response to cutaneous fungal infections, a primary infection with Candida albicans was established by inoculating this organism on the occluded skin of Tg and non-Tg mice. These infections resolved 7 days after removal of occlusive dressing in all three groups of mice, without evidence of exaggerated inflammation in either the Tg or non-Tg mice. Only B7-2 Tg mice developed enhanced Th1-lymphocyte-mediated immune responses to C. albicans antigens after resolving this infection: enhanced footpad swelling in response to intradermal C. albicans antigens, enhanced production of mRNA encoding Th1 lymphokines in draining lymph nodes, and increased gamma interferon secreted into culture supernatants by lymph node T lymphocytes stimulated with Candida antigens in vitro. Lastly, Western blotting of sera from mice that had resolved this fungal infection indicated that only B7-2 Tg mice recognized a wide range of Candida-associated antigens. These data suggest that these two costimulatory molecules, when expressed by keratinocytes, do not deliver identical signals to C. albicans antigen-reactive Th1 lymphocytes. The enhanced immune response in B7-2 Tg mice to a cutaneous C. albicans infection demonstrates the importance of antigen presentation and costimulation in immune reactivity to fungi. Furthermore, B7-2 Tg mice may be useful in identification of protective Candida antigens.

Epidermal growth factor protects against carbon tetrachloride-induced hepatic injury

1. Epidermal growth factor (EGF) is known to protect the gastrointestinal tract against various noxious agents. Its potential value in preventing/ treating hepatic injury is, however, largely unexplored. We therefore examined whether EGF could influence CCl4-induced hepatic injury. 2. Female Sprague-Dawley rats (8 per group) received saline or recombinant EGF (500 or 750 micrograms/kg, intraperitoneal) 30 min before CCl4 (20% v/v, in olive oil, intraperitoneal). Eighteen hours later, animals were killed, serum was collected for assay of biochemical markers of hepatic injury and livers were removed for histological analyses. 3. Administration of CCl4 resulted in severe hepatic necrosis and caused a 10-fold rise in plasma alanine aminotransferase levels compared with levels seen in control animals (218 +/- 15 compared with 23 +/- 9 mumol/l in controls, mean +/- SEM, P < 0.01). Serum malondialdehyde levels, used as a marker of lipid peroxidation, showed a 2-fold rise in response to CCl4 treatment (median 4.0, quartile range 3.3-5.8 units/l compared with median 2.3, quartile range 2.1-2.5 units/l in controls, P < 0.05). Administration of EGF at 500 micrograms/kg, before the CCl4, did not protect against injury, as assessed by histology or rise in plasma alanine aminotransferase levels. In contrast, animals given EGF at 750 micrograms/kg, before the CCl4, had only minimal changes in histology, with only a minor rise in alanine aminotransferase levels (37 +/- 4 compared with 23 +/- 9 mumol/l in animals not given CCl4) and had no significant rise in malondialdehyde levels. 4. EGF protects against CCl4-induced hepatic injury and may provide a novel approach to the treatment of liver damage.

Longitudinal study of plasma HIV-1 RNA concentrations during the asymptomatic stage of HIV infection measured using AMPLICOR HIV monitor and NASBA HIV-1 RNA QT tests. ACCTES Association

The predictive value of two methods for measuring HIV RNA concentration in plasma was assessed in relation to CD4 lymphocyte counts during the asymptomatic period of infection. The design was a retrospective longitudinal case-control study for a mean period of 60 months involving 20 asymptomatic patients included in the French National prospective survey. The CD4 counts in these patients during the last 36 months of the study were stable (non-progressors) or declined (progressors). Plasma RNA concentrations were determined in each subject annually using the AMPLICOR and NASBA techniques. Only AMPLICOR gave RNA titers above the cut-off value for all the patients. The techniques agreed satisfactorily, although there was a difference, median 0.4 log10, between the AMPLICOR and NASBA values. The non-progressors had low and stable RNA concentrations. The concentration was higher in the progressors, according to the AMPLICOR technique, from their inclusion in the study, and according to the NASBA technique, from 1 year after inclusion. However, only four of ten individual progressors had stable plasma HIV RNA concentrations significantly above those of the non-progressors before the decline in their CD4 counts. These were all and only the patients with a decline in lymphocyte counts more than 100 CD4/mm3/year. In each of the other progressors, the RNA concentration was not significantly different from those of the non-progressors. Thus, when making decisions about therapy, plasma HIV RNA determinations cannot be used in place of CD4 counts and may provide valuable additional information.

Synaptophysin immunoreactivity in the aging rat pituitary gland

The density of synaptophysin (SN)-immunoreactivity (IR) was examined in pituitary glands of aging male Sprague-Dawley rats. SN-IR was observed as dense dots among endocrine cells of the intermediate lobe, while the neural lobe contained numerous, highly dense immunopositive regions. Some anterior lobe secretory cells contained SN-IR within the cytoplasm, suggestive of the presence of the protein in secretory granules, but no dot-like staining was observed between endocrine cells of that region. A quantitative analysis of the dot-like SN-immunostaining within the intermediate lobe found that tissue from groups of rats aged 13 months, or 15-17 months, contained significantly fewer SN-immunopositive areas than did tissues from 8-month-old animals. Diminished SN immunostaining is suggestive of reduced numbers of synapses in the intermediate lobe, which may lead to alterations in regulation of pituitary hormone secretion from endocrine cells in the older animals.

Alterations in GAP-43-immunoreactive innervation in the aging rat pituitary

The levels and distribution of the growth-associated protein, GAP-43, were examined in the pituitary glands of young and aging Sprague-Dawley rats, using immunohistochemical techniques on tissue sections and Western blot analyses. GAP-43-immunoreactive innervation was observed in sections in the intermediate and neural lobes of animals aged 8-15 months, while in the oldest rats studied (17 months), stained fibers were observed mainly in the neural, but not the intermediate lobe. Western blots revealed reduced levels of GAP-43 in samples from 15 month old animals, as compared to 12 month old rats, in the neurointermediate lobes. There was no immunoreactivity for GAP-43 in the anterior lobes in the tissue sections or in the blots in any of the glands examined. A diminished level of GAP-43 in pituitary innervation in aged animals suggests a reduced ability for nerve terminals to undergo 'plastic' changes in their relationship to target endocrine cells. Since GAP-43 has also been suggested to modulate neurotransmitter release, a reduction in the protein in aging nerve terminals may diminish availability of transmitters at presynaptic sites.

HEMOCO: a French prospective study of hemophiliacs infected by human immunodeficiency virus type 1 (HIV-1)

HEMOCO is a multicenter prospective cohort set up in 1989 to monitor 407 French hemophiliacs infected by HIV-1 and recruited in 4 hemophilia treatment centers in the Paris region. As of 15 July 1995, 42% of the patients in the cohort had developed stage B HIV disease and 29% stage C disease (AIDS); 23.1% of the patients had died. The cumulative proportion of patients with AIDS was 4.5% at 5 years and 27.4% at 10 years, while the respective mortality rates were 3.8% and 19.5%. In our study, only age was predictive of AIDS, with an estimated relative risk of 1.2 per 10-year age increment; this factor was also predictive of death. After 10 years of follow-up, 6.1% of the study population had no clinical or laboratory signs of immunodepression. The follow-up protocol in the HEMOCO protocol is the same as that in the French SEROCO study, which includes men infected by HIV-1 through sexual contact. This will allow us to compare the progression of HIV infection between these two exposure groups.

Regulation of pituitary beta-endorphin secretion in aging rats: in vitro responsiveness to dopamine

The intermediate lobe of the mammalian pituitary is highly responsive to dopamine inhibition of beta-endorphin secretion. In this study, the ability of aged (12 months) intermediate lobes to respond to dopamine was compared to that of young (6 weeks) tissue, using a short-term in vitro incubation of isolated rat neurointermediate lobes, with measurement of peptide release by radioimmunoassay. Tissue from the aged rats released greater amounts of beta-endorphin peptide than amounts measured from young tissue at all time periods studied. The aged lobes were also found to be significantly more sensitive to dopamine than young glands, as measured by percent change of each group compared to respective baseline release. In comparison, incubation of tissue from young animals in which the intermediate lobe had been acutely denervated by treating rats with injections of the catecholamine neurotoxin, 6-hydroxydopamine, did not differ in responsiveness to dopamine as compared to tissue from control rats. The observations suggest that aging intermediate lobe, while being hypersecretory, is supersensitive to dopamine, perhaps as the result of gradually reduced innervation.

Effect of circulating factors on vascular smooth muscle contraction and its calcium uptake in uremia

Uremia is often associated with alterations in calcium metabolism and vascular smooth muscle function in hypertension and atherosclerosis. The ways in which these conditions inter-relate are not clearly understood. In order to study the possibility that circulating factors might influence smooth muscle function, experiments were performed on rat aortic strips. The serum from both uremic patients and rats enhanced the norepinephrine-induced contraction (NEIC) and net 45-calcium uptake in rat aortic strips. In a similar manner, the serum of parathyroidectomized uremic rats also increased the NEIC, whereas verapamil reduced the aortic response to levels below those of the control, in the presence of uremic serum. These findings suggest that in both chronic (patients) and early (rats) stages of uremia, there is a circulating factor, different from parathyroid hormone, that affects calcium uptake and vascular smooth muscle contraction.

[Prevalence of alcoholic diseases. At a teaching hospital of the Paris suburbs]

During the last 15 days of January 1989, the 757 patients admitted for more than 48 hours in any of the departments of Hôpital Beaujon (Clichy) were investigated for diseases that were certainly or probably related to alcoholism, and in order to detect drinkers at high risk, the amount of alcohol consumed in a week was recorded. The prevalence of alcohol-related diseases was 14.7 per cent (range: 12.2 per cent-17.2 per cent) and that of alcohol consumers at high risk was 4.2 per cent (range: 2.8 per cent-5.6 per cent).