Analysis of Risk Factors for a Low Immune Response to Messenger RNA COVID-19 Vaccine in Kidney Transplant Recipients and Differences Between Second and Third Dose

BACKGROUND

The efficacy of the response to SARS-CoV-2 vaccination in kidney transplant recipients is low. The aim of our study was to evaluate the risk factors correlated with the low antibody response and whether there was an improvement between the second and the third dose.

METHODS

A prospective study was conducted on 176 kidney transplant recipients who received the second and the third dose of the anti-SARS-CoV-2 mRNA Comirnaty vaccine. We evaluated the seroconversion process after administration of the second and the third dose and assessed a possible correlation with age, time between transplant and vaccination, and type of immunosuppressive therapy.

RESULTS

A total of 98 of the 176 patients (55.7%) responded positively after the inoculation of the second dose and according to the multivariable logistic regression analysis the lack of seroconversion was independently associated with patient age ≥60 (P = .025; odds ratio [OR], 2.094), time since transplant of 1 to 3 months (P = .032; OR, 2.118), and triple therapy (P = .044; OR, 2.327). After the vaccine third dose, the seroconversion increased to 62.5%, and it was negatively influenced by calcineurin inhibitor use (12/21, 57.1% vs 71/78, 91.0%, P = .0006) and triple therapy (13/21, 61.9% vs 72/78, 92.3%, P = .0014). The median of antispike antibody response significantly increased from 18.5 IU/mL after the second dose to 316.9 IU after the third dose (P < .0001).

CONCLUSIONS

We demonstrated a correlation between older age and shorter distance from the transplant and triple immunosuppressive therapy with the lack of seroconversion. We noticed a significant improvement in antibody response by a third dose of messenger RNA vaccine.

Discovery of 4-((1-(1H-imidazol-2-yl)alkoxy)methyl)pyridines as a new class of Trypanosoma cruzi growth inhibitors

The identification of a new series of growth inhibitors of Trypanosoma cruzi, the causative agent of Chagas' disease, is described. In vitro screening of a subset of compounds from our in-house compound collection against the parasite led to the identification of hit compound 1 with low micromolar inhibition of T. cruzi growth. SAR exploration on the hit compound led to the identification of compounds that show nanomolar parasite growth inhibition (T. cruzi EC₅₀ ≤ 100 nM) and no cytotoxicity in human cells (HeLa CC₅₀ > 50 μM). Further investigation identified CYP51 inhibition (compound 11 CYP51 IC₅₀ 52 nM) as a possible mechanism of action of this new class of anti-parasitic agents.

Improved Selective Class I HDAC and Novel Selective HDAC3 Inhibitors: Beyond Hydroxamic Acids and Benzamides

The application of class I HDAC inhibitors as cancer therapies is well established, but more recently their development for nononcological indications has increased. We report here on the generation of improved class I selective human HDAC inhibitors based on an ethylketone zinc binding group (ZBG) in place of the hydroxamic acid that features the majority of HDAC inhibitors. We also describe a novel set of HDAC3 isoform selective inhibitors that show stronger potency and selectivity than the most commonly used HDAC3 selective tool compound RGFP966. These compounds are again based on an alternative ZBG with respect to the ortho-anilide that is featured in HDAC3 selective compounds reported to date.

Gender, lifestyles, illness perception and stress in stable atrial fibrillation

AIMS

The study is aimed at investigating if perceived stress in Stable Atrial Fibrillation (AF) has any gender-associated feature and relationships with lifestyle indicators and education level, and which relationship self efficacy, anxiety and depression and illness perception have, if any.

PATIENTS AND METHODS

88 consecutive patients referred for stable AF are studied by Psychological Stress Measure (PSM) test, Illness Perception Questionnaire (IPQ-R), Generalized Self-Efficacy scale (GSE) and Hospital Anxiety and Depression Scale (HADS). Mediterranean diet, physical activity increase and smoking withdrawal counseling were provided.

RESULTS

AF patients have higher PSM associated with gender (women), older age, anxiety and depression. Higher GSE, greater Adherence to Mediterranean Diet profile and coffee habits (greater coffee users) are associated with a reduced hazard of perceived stress. By multiple linear regression, PSM is explained by Anxiety and IPQr (statistically significant are emotional representation and illness coherence subscales), which account for 92.2% of the variance (p<0.0001).

CONCLUSION

Our results outline that psychological stress is greater in women in comparison with men. Illness perceptions are important in the context of perceived stress in AF. This effect appears to be modulated by greater self-efficacy and by Adherence to Mediterranean Diet profile, that when higher, are associated with a reduced hazard of perceived stress. We suggest that therapeutic interventions on illness perceptions can be warranted in order to achieve a lower psychological distress in AF patients.

Stress, abdominal obesity and intrarenal resistive index in essential hypertension

AIM

Although it is commonly believed that a strong causal link exists between psychological stress and hypertension, as well with other factors, such as obesity, just what kind of empirical evidence supports this assumption is still controversial. The aim of the study is to investigate if perceived stress have any interference with intrarenal resistance and hence with mechanisms related to Essential Hypertension (EH) and if Anxiety, Depression, Self efficacy and Illness Perception can account for perceived stress.

PATIENTS AND METHODS

Obesity, insulin resistance (HOMA), Doppler Renal Resistive Index (RRI) and glomerular filtration rate (GFR) are studied along with Psychological Stress Measure (PSM), Illness Perception Questionnaire (IPQ-R), Generalized Self-Efficacy scale (GSE) and Hospital Anxiety and Depression Scale (HADS) in 119 hypertensive patients referred for stable lasting EH, and 150 normal controls. Lower salt/lower calories Mediterranean diet, physical activity increase and smoking withdrawal counseling were provided.

RESULTS

By Odds Ratios, higher risk of EH is associated with greater perceived stress, older age, lower GFR, obesity, greater RRI and insulin resistance. By Multiple Linear Regression the most significant variable that accounts for higher RRI are abdominal obesity and arterial pulse pressure; the only significant independent psychological variable that accounts for abdominal obesity are PSM and identity IPQ subscale. Self-Efficacy anxiety and Illness perception subscales (IPQr), accounts significantly for 62.0% of the variance to PSM, with possible effects on RRI and on the pathophysiological hypertension cascade.

CONCLUSION

Worst identity and treatment control perceptions of EH, and a lower self-efficacy are the main psychological factors accounting for a greater stress. Interventions aimed to reduce perceived stress can be warranted in EH.

Pain assessment in fibromyalgia and rheumatoid arthritis: influence of physical activity and illness perception

OBJECTIVE

Pain visual analog scales (VAS) have been validated for clinical use in fibromyalgia (FM) and rheumatoid arthritis (RA) patients. There are potential limitations, however, not only considering their use as a continuous measurement, but also with regard to the influence of personal illness perceptions, habitual physical activity and other life-style features. The aim of the study was to ascertain whether different illness perception, physical activity and clinical and laboratory characteristics can predict the severity of perceived pain assessed by VAS.

MATERIALS AND METHODS

This is an observational comparative study of forty consecutive out-patients, 20 of them with fibromyalgia and 20 with rheumatoid arthritis, treated by medical and physical therapy. Patients were assessed also by Pain VAS, Health Assessment Questionnaire (HAQ) disability index, Ritchie index, Baecke questionnaire for physical activity, Illness Perception Questionnaire (IPQr) and SF36.

RESULTS

Pain VAS is explained differently by some of the studied variables: in the total group HAQ and Ritchie index explain 29.8% of the variance; in the RA patients number of joints with pain and Ritchie index explain 52.7% of the variance; in FM patients total SF36 score and IPQr personal control dimension explains 44.7% of the variance. No definite role of anxiety and/or depression was found as predictor of perceived pain and disability.

CONCLUSION

Pain perception and complaint are explained by belief in FM patients: This seems to suggest the need for a more articulated cognitive approach; addressing both diagnostic and therapeutic interventions to anxiety/depression issues is not supported by our results.

Novel P2-P4 macrocyclic inhibitors of HCV NS3/4A protease by P3 succinamide fragment depeptidization strategy

Hepatitis C represents a serious worldwide health-care problem. Recently, we have disclosed a novel class of P2-P4 macrocyclic inhibitors of NS3/4A protease containing a carbamate functionality as capping group at the P3 N-terminus. Herein we report our work aimed at further depeptidizing the P3 region by replacement of the urethane function with a succinamide motif. This peptidomimetic approach has led to the discovery of novel P2-P4 macrocyclic inhibitors of HCV NS3/4A protease with sub-nanomolar enzyme affinities. In addition to being potent inhibitors of HCV subgenomic replication, optimized analogues within this series have also presented attractive PK properties and showed promising liver levels in rat following oral administration.

Discovery of raltegravir, a potent, selective orally bioavailable HIV-integrase inhibitor for the treatment of HIV-AIDS infection

Human immunodeficiency virus type-1 (HIV-1) integrase is one of the three virally encoded enzymes required for replication and therefore a rational target for chemotherapeutic intervention in the treatment of HIV-1 infection. We report here the discovery of Raltegravir, the first HIV-integrase inhibitor approved by FDA for the treatment of HIV infection. It derives from the evolution of 5,6-dihydroxypyrimidine-4-carboxamides and N-methyl-4-hydroxypyrimidinone-carboxamides, which exhibited potent inhibition of the HIV-integrase catalyzed strand transfer process. Structural modifications on these molecules were made in order to maximize potency as HIV-integrase inhibitors against the wild type virus, a selection of mutants, and optimize the selectivity, pharmacokinetic, and metabolic profiles in preclinical species. The good profile of Raltegravir has enabled its progression toward the end of phase III clinical trials for the treatment of HIV-1 infection and culminated with the FDA approval as the first HIV-integrase inhibitor for the treatment of HIV-1 infection.

Integrase inhibitors for the treatment of HIV infection

HIV-1 integrase catalyzes the insertion of HIV-1 DNA into the genome of the host cell and, therefore, represents a rational target for chemotherapeutic intervention in the treatment of HIV-1 infection. Raltegravir, marketed as Isentress, is the first integrase inhibitor to be approved by the FDA for the treatment of HIV AIDS infection. This review briefly describes the successful medicinal chemistry efforts that culminated in the discovery of raltegravir, and highlights more recent progress that has been made in the field of HIV-1 integrase inhibition.

4-Hydroxy-5-pyrrolinone-3-carboxamide HIV-1 integrase inhibitors

The viral enzyme integrase is essential for the replication of HIV-1 and, after the discovery of Isentress, represents a validated target for anti-retroviral therapy. Incorporation of the dihydroxycarbonyl pharmacophore into a pyrrolinone scaffold led to the discovery of 5-pyrrolinone-3-carboxamides as a structurally diverse class of HIV-1 integrase inhibitors.

Discovery and Synthesis of HIV Integrase Inhibitors: Development of Potent and Orally Bioavailable N-Methyl Pyrimidones

The human immunodeficiency virus type-1 (HIV-1) encodes three enzymes essential for viral replication: a reverse transcriptase, a protease, and an integrase. The latter is responsible for the integration of the viral genome into the human genome and, therefore, represents an attractive target for chemotherapeutic intervention against AIDS. A drug based on this mechanism has not yet been approved. Benzyl-dihydroxypyrimidine-carboxamides were discovered in our laboratories as a novel and metabolically stable class of agents that exhibits potent inhibition of the HIV integrase strand transfer step. Further efforts led to very potent compounds based on the structurally related N-Me pyrimidone scaffold. One of the more interesting compounds in this series is the 2-N-Me-morpholino derivative 27a, which shows a CIC95 of 65 nM in the cell in the presence of serum. The compound has favorable pharmacokinetic properties in three preclinical species and shows no liabilities in several counterscreening assays.

Dihydroxypyrimidine-4-carboxamides as novel potent and selective HIV integrase inhibitors

Human immunodeficiency virus type-1 (HIV-1) integrase, one of the three constitutive viral enzymes required for replication, is a rational target for chemotherapeutic intervention in the treatment of AIDS that has also recently been confirmed in the clinical setting. We report here on the design and synthesis of N-benzyl-5,6-dihydroxypyrimidine-4-carboxamides as a class of agents which exhibits potent inhibition of the HIV-integrase-catalyzed strand transfer process. In the current study, structural modifications on these molecules were made in order to examine effects on HIV-integrase inhibitory potencies. One of the most interesting compounds for this series is 2-[1-(dimethylamino)-1-methylethyl]-N-(4-fluorobenzyl)-5,6-dihydroxypyrimidine-4-carboxamide 38, with a CIC95 of 78 nM in the cell-based assay in the presence of serum proteins. The compound has favorable pharmacokinetic properties in preclinical species (rats, dogs, and monkeys) and shows no liabilities in several counterscreening assays, highlighting its potential as a clinically useful antiviral agent.

4,5-dihydroxypyrimidine carboxamides and N-alkyl-5-hydroxypyrimidinone carboxamides are potent, selective HIV integrase inhibitors with good pharmacokinetic profiles in preclinical species

The dihydroxypyrimidine carboxamide 4a was discovered as a potent and selective HIV integrase strand transfer inhibitor. The optimization of physicochemical properties, pharmacokinetic profiles, and potency led to the identification of 13 in the dihydroxypyrimidine series and 18 in the N-methylpyrimidinone series having low nanomolar activity in the cellular HIV spread assay in the presence of 50% normal human serum and very good pharmacokinetics in preclinical species.

Evaluation of a primary care-oriented brief counselling intervention for obesity with and without orlistat

OBJECTIVE

There is a significant need for an obesity treatment model suitable for the primary care environment. We examined the effectiveness of a brief counselling intervention alone, in combination with orlistat, and drug-alone in a 12-month randomized-clinical trial at a medical school obesity centre.

METHODS

Participants (N = 250) with body mass index (BMI) >or=27 were randomized. Changes in body weight, lipids, blood pressure and serum glucose were examined. Drug adherence and attendance were also evaluated.

RESULTS

Completers analysis was conducted on 136 participants with data at baseline, 6 and 12 months and intention-to-treat analyses (ITT) for the total sample. Amongst completers, participants in the drug only (P = 0.012) and drug + brief counselling (P = 0.001) groups lost more weight (mean +/- SD: -3.8 +/- 5.8 kg and -4.8 +/- 4.4 kg, respectively) than participants in the brief counselling only group at 6 months (-1.7 +/- 3.3 kg), but there were no significant group differences at 12 months. ITT model results were similar to completers at 6 months and remained significant at 12 months, but the weight losses were more modest (<3 kg) for both groups receiving orlistat. For brief counselling alone, participants gained weight (1.7 +/- 4.2 kg). Cardiovascular disease (CVD) parameter changes were negligible.

CONCLUSIONS

Pharmacotherapy alone or combined with brief counselling resulted in modest weight losses that had minimal impact on cardiovascular parameters, but were greater than brief counselling alone. Whilst brief interventions and primary pharmacotherapy have been suggested as viable treatments for implementation in primary care settings, our study suggests that such minimal interventions provide minimal benefits.

Weight loss with meal replacement and meal replacement plus snacks: a randomized trial

OBJECTIVE

To evaluate whether snacking would improve weight loss and weight maintenance in overweight individuals within the context of a structured meal replacement (MR) weight loss program.

DESIGN

A prospective 24 week, 2 (snacking vs nonsnacking) x 2 (MR vs meal replacement augmented with snacks (MRPS)) randomized trial. Participants were instructed to limit their total daily intake to 1200 (women) or 1500 (men) kcals. Those receiving the MR program were instructed not to snack while those in the MRPS program were told to snack three times per day.

SUBJECTS

A total of 100 participants were block-randomized, based on prestudy snacking status (high vs low), to receive a standard meal replacement program (MR) or MRPS.

MEASUREMENTS

Weight, height, blood pressure, lipid fractions, glucose, and insulin were assessed at the baseline, 12-, and 24 weeks.

RESULTS

Completers analysis at 24 weeks demonstrated a significant time effect (F(1,46)=44.6, P<0.001), indicating that all participants lost significant amounts of weight regardless of group assignment. An intention-to-treat model resulted in similar results. By week 24, the average weight loss across groups was 4.6 kg. There also were significant improvements across all groups among completers for systolic blood pressure (P=0.047), cholesterol (P=0.001), LDL (P=0.001), glucose (P=0.004), and insulin (P=0.001) at week 12, and glucose (P=0.001) and insulin at week 24 (P=0.003).

CONCLUSIONS

Our results suggest that a participant's preferences for snacking did not affect their response to treatment. Snackers and nonsnackers responded equally well whether they received a standard meal replacement program or one augmented with snacks.

Analysis of changes in optical fibers during arc-fusion splicing by use of quantitative phase imaging

A non-interferometric imaging technique in conjunction with Abel inversion is used to directly and quantitatively examine the changes in optical fibers due to the heating produced during arc-fusion splicing as a function of fusion arc parameters. Phase images in the vicinity of a fusion splice are obtained using Quantitative Phase Microscopy, allowing the refractive-index change to be reconstructed with high spatial resolution. This simple, nondestructive method confirms that, for a fixed arc current, while the fusion time increases, the refractive-index of both fiber cores within the fusion region decreases in magnitude, the core region broadens, and the axial gradient decreases.

The monoethyl ester of meconic acid is an active site inhibitor of HCV NS5B RNA-dependent RNA polymerase

Screening of the in-house sample collection for compounds with HCV NS5B RNA dependent RNA polymerase inhibition led to the identification of a new lead. Afterwards, we discovered that the screening lead, rather than containing the expected structure 1, was comprised of roughly a 1:1 mixture of meconic acid 2 and its monoethyl ester 3, with all inhibitory potency residing with 3. We propose that this compound shares critical common features for activity with alpha,gamma-diketoacids inhibitors previously discovered by our group. SAR around this molecule will be presented to provide an improved basis for structure-based ligand design.

HCV NS5b RNA-dependent RNA polymerase inhibitors: from alpha,gamma-diketoacids to 4,5-dihydroxypyrimidine- or 3-methyl-5-hydroxypyrimidinonecarboxylic acids. Design and synthesis

A new class of the HCV NS5b RNA-dependent RNA polymerase inhibitors, the dihyroxypyrimidinecarboxylic acid derivative, was designed from a diketoacid and meconic acid derivative discovered by screening. Mechanism of action and essential moieties required for activity were identified. The corresponding N-methylpyrimidinone was also prepared; both classes are novel, reversible, and selective inhibitors of the HCV NS5b polymerase with improved druglike characteristics.

Gliotoxin is a dual inhibitor of farnesyltransferase and geranylgeranyltransferase I with antitumor activity against breast cancer in vivo

Gliotoxin is a natural mycotoxin with immunosuppressive and antimicrobial activity. Inhibition of farnesyltransferase (IC50 80 microM) and geranylgeranyltransferase I (IC50 17 microM) stimulated interest in the potential antitumor activity of this epidithiodioxopiperazine. Gliotoxin inhibited proliferation of six breast cancer cell lines in culture with mean +/- SD IC50 289 +/- 328 microM (range 38-985 microM); intracellular farnesylation of Lamin B and geranylgeranylation of Rap1A were inhibited in a dose-dependent manner. In randomized controlled studies using the N-methyl-N-nitrosourea rat mammary carcinoma model, gliotoxin had pronounced antitumor activity in vitro and little systemic toxicity when administered to 10 animals at 10 mg/kg by subcutaneous injection weekly for 4 wk compared with 10 controls. Single doses up to 25 mg/kg were well tolerated. The present studies confirm that gliotoxin is a dual inhibitor of farnesyltransferase and geranylgeranyltransferase I with pronounced antitumor activity and favorable toxicity profile against breast cancer in vitro and in vivo.

Refractive index profiles of Ge-doped optical fibers with nanometer spatial resolution using atomic force microscopy

We show a quantitative connection between Refractive Index Profiles (RIP) and measurements made by an Atomic Force Microscope (AFM). Germanium doped fibers were chemically etched in hydrofluoric acid solution (HF) and the wet etching characteristics of germanium were studied using an AFM. The AFM profiles were compared to both a concentration profile of the preform determined using a Scanning Electron Microscope (SEM) and a RIP of the fiber measured using a commercial profiling instrument, and were found to be in excellent agreement. It is now possible to calculate the RIP of a germanium doped fiber directly from an AFM profile.

Discovery of alpha,gamma-diketo acids as potent selective and reversible inhibitors of hepatitis C virus NS5b RNA-dependent RNA polymerase

alpha,gamma-Diketo acids (DKA) were discovered from screening as selective and reversible inhibitors of hepatitis C virus NS5b RNA-dependent RNA polymerase. The diketo acid moiety proved essential for activity, while substitution on the gamma position was necessary for selectivity and potency. Optimization led to the identification of a DKA inhibitor of NS5b polymerase with IC(50) = 45 nM, one of the most potent HCV NS5b polymerase inhibitors reported.

Synthesis of Medium-Ring Nitrogen Heterocycles via Palladium-Catalyzed Heteroannulation of 1,2-Dienes

Seven-, eight-, and nine-membered-ring nitrogen heterocycles are readily prepared by the palladium-catalyzed heteroannulation of a variety of 1,2-dienes by a range of tosylamide- and amine-containing aryl and vinylic halides. The ease of ring formation is seven > eight > nine, and better results are obtained using aryl halides, rather than vinylic halides, and tosylamide functionality, rather than amine functionality. The reaction is suggested to proceed by the formation and addition of an aryl or vinylic palladium compound to the allene to generate a pi-allylpalladium intermediate, which subsequently undergoes nucleophilic displacement of palladium at the less hindered end of the pi-allyl system.

Human estrogen receptor beta binds DNA in a manner similar to and dimerizes with estrogen receptor alpha

The cloning of a novel estrogen receptor beta (denoted ERbeta) has recently been described (Kuiper, G. G. J. M., Enmark, E., Pelto-Huikko, M., Nilsson, S., and Gustafsson, J-A. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 5925-5930 and Mosselman, S., Polman, J. , and Dijkema, R. (1996) FEBS Lett. 392, 49-53). ERbeta is highly homologous to the "classical" estrogen receptor alpha (here referred to as ERalpha), has been shown to bind estrogens with an affinity similar to that of ERalpha, and activates expression of reporter genes containing estrogen response elements in an estrogen-dependent manner. Here we describe functional studies comparing the DNA binding abilities of human ERalpha and beta in gel shift assays. We show that DNA binding by ERalpha and beta are similarly affected by elevated temperature in the absence of ligand or in the presence of 17beta-estradiol and the partial estrogen agonist 4-hydroxy-tamoxifen. In the absence of ligand, DNA binding by ERalpha and beta is rapidly lost at 37 degrees C, while in the presence of 17beta-estradiol and 4-hydroxy-tamoxifen, the loss in DNA binding at elevated temperature is much more gradual. We show that the loss in DNA binding is not due to degradation of the receptor proteins. However, while the complete antagonist ICI 182, 780 does not "protect" human ERalpha (hERalpha) from loss of DNA binding at elevated temperature in vitro, it does appear to protect human ERbeta (hERbeta), suggestive of differences in the way ICI 182, 780 acts on hERalpha and beta. We further report that ERalpha and beta can dimerize with each other, the DNA binding domain of hERalpha being sufficient for dimerization with hERbeta. Cell and promoter-specific transcription activation by ERalpha has been shown to be dependent on the differential action of the N- and C-terminal transcription activation functions AF-1 and AF-2, respectively. The existence of a second estrogen receptor gene and the dimerization of ERalpha and beta add greater levels of complexity to transcription activation in response to estrogens.

Idoxifene is equipotent to tamoxifen in inhibiting mammary carcinogenesis but forms lower levels of hepatic DNA adducts

Tamoxifen is an effective agent preventing mammary carcinogenesis in rats but causing liver tumours. Idoxifene is a more potent antioestrogen and is effective in patients with advanced breast cancer. We therefore compared the effects of idoxifene with tamoxifen on mammary carcinogenesis and hepatic DNA adduct formation. To do this, we undertook a study designed to compare tamoxifen with idoxifene as a chemopreventive agent in rats inoculated with N-methylnitrosourea (MNU) and also measured hepatic adduct formation. We examined the time to mammary tumour development in 272 female Ludwig/Wistar/Olac rats treated with MNU followed by tamoxifen (5 mg kg(-1)), equimolar idoxifene or vehicle three times a week for up to 24 weeks. To determine duration of effect, a second study was carried out whereby all of the 129 animals surviving at the end of treatment were entered into a surveillance programme for 27 weeks after the end of the administration period. Hepatic DNA adduct formation was examined by 32P-postlabelling in a group of rats after 24 weeks' treatment. In the first study, both idoxifene and tamoxifen were effective in preventing tumour growth as only 2 out of 21 (10%) MNU and vehicle-treated animals were alive and tumour free after 24 weeks compared with 13 out of 22 (59%) animals receiving MNU followed by idoxifene or tamoxifen (P < 0.001). The second study showed that, in both idoxifene- and tamoxifen-treated animals, a progressive regrowth of tumours occurred after cessation of therapy, as by the end of the observation period only four idoxifene-treated animals and one tamoxifen-treated animal were free from disease. In the subset of animals tested, tamoxifen-treated animals had approximately 100 times higher levels of DNA hepatic adducts than idoxifene-treated animals. Adducts were not seen in the control group. These results indicate that idoxifene is as effective a chemopreventive agent as tamoxifen in the rat while causing only very low levels of DNA adducts in liver tissue and suggest that idoxifene may be a well-tolerated chemopreventive agent in women who are at increased risk of breast cancer.

High-energy hybrid Raman optical parametric amplifier eye safe laser source

A high-energy eye safe laser source at 1.54 µm is demonstrated experimentally by using a hybrid system of stimulated Raman scattering and optical parametric amplification pumped by a single 1.06-µm Nd:YAG laser source. This system overcomes some of the technical problems that occur in conventional eye safe lasers, such as optical breakdown and thermal blooming in the Raman laser, and thermal conduction problems in the erbium-doped glass solid-state laser that limit the repetition rate when high-energy output is sought. Thus this hybrid design provides a simple system that could provide a high pulse energy output (> 50 mJ) at a repetition rate of greater than 10 Hz.