A Dual Effect of Dopamine on Hippocampal LTP and Cognitive Functions in Control and Kindled Mice

The impact of dopamine on synaptic plasticity and cognitive function following seizure is not well understood. Here, using optogenetics in the freely behaving animal, we examined exploratory behavior and short-term memory in control and kindled male mice during tonic stimulation of dopaminergic neurons within the ventral tegmental area (VTA). Furthermore, using field potential recording, we compared the effect of dopamine on synaptic plasticity in stratum radiatum and stratum oriens layers of both ventral and dorsal hippocampal CA1 regions, and again in both control and kindled male mice. Our results demonstrate that tonic stimulation of VTA dopaminergic neurons enhances novelty-driven exploration and short-term spatial memory in kindled mice, essentially rescuing the seizure-induced cognitive impairment. In addition, we found that dopamine has a dual effect on LTP in control versus kindled mice, such that application of dopamine prevented LTP induction in slices from control mice, but rescued LTP in slices taken from the kindled animal. Taken together, our results highlight the potential for dopaminergic modulation in improving synaptic plasticity and cognitive function following seizure.

Effects of optogenetic and visual stimulation on gamma activity in the visual cortex

Studying brain functions and activity during gamma oscillations can be a challenge because it requires careful planning to create the necessary conditions for a controlled experiment. Such an experiment consists of placing the brain into a gamma state and investigating cognitive processing with a careful design. Cortical oscillations in the gamma frequency range (30-80 Hz) play an essential role in a variety of cognitive processes, including visual processing and cognition. The present study aims to investigate the effects of a visual stimulus on the primary visual cortex under gamma oscillations. Specifically, we sought to explore the behavior of gamma oscillations triggered by optogenetic stimulation in the II and IV layers of the visual cortex, both with and without concurrent visual stimulation. Our results show that optogenetic stimulation increases the power of gamma oscillation in both layers of the visual cortex. However, the combined stimuli resulted in a reduction of gamma power in layer II and an increase and reinforcement in gamma power in layer IV. Modelling the results with the Wilson-Cowan model suggests changes in the input of the excitatory population due to the combined stimuli. In addition, our analysis of the data using the Lempel-Ziv complexity method supports our interpretations from the modeling. Thus, our results suggest that optogenetic stimulation enhances low gamma power in both layers of the visual cortex, while simultaneous visual stimulation has differing effects on the two layers, reducing gamma power in layer II and increasing it in layer IV.

Levels of DNA, Protein, Lipid Oxidation and Apoptosis Biomarkers in Semen of Men with Hyperviscous Semen: A Cross-Sectional Study

BACKGROUND

Semen hyperviscosity is a threatening cause of abnormal spermatozoa and infertility in men. We aimed to evaluate oxidative stress, antioxidants depletion and sperm apoptosis as main reasons for poor quality of spermatozoa in men with hyperviscous semen.

MATERIALS AND METHODS

In this cross-sectional study, ejaculate specimens were collected from fertile (n=102) and infertile men with hyperviscous semen (n=123) and without semen hyperviscosity (n=143). Total antioxidant capacity (TAC), glutathione (GSH), malondialdehyde (MDA), protein carbonyl (PC), 8-hydroxydeoxyguanosine (8-OHdG), and were measured in semen samples to estimate oxidative stress status. Gene expression pattern of BAX, CASPASE-9, CASPASE-3, and BCL2 was assessed to estimate sperm apoptosis.

RESULTS

The average of sperm count, normal morphology, normal motility, and sperm vitality in men with hyperviscous semen was significantly lower than infertile subjects without hyperviscous semen (P<0.01). Men with hyperviscous semen exhibited higher levels of PC (8.34 ± 1.03 nmol/mg vs. 6.01 ± 0.93 nmol/mg, P=0.008), MDA (1.14 ± 0.27 nmol/ ml vs. 0.89 ± 0.22 nmol/ml, P=0.031), 8-OHdG (259.71 ± 24.59 ng/ml vs. 197.13 ± 18.47 ng/ml, P=0.009), but lower TAC contents (1250.44 ± 66.23 μM/L vs. 1784.31 ± 89.87 μM/L, P=0.018) and GSH (3.82 ± 1.05 μM vs. 5.89 ± 0.87 μM, P=0.021) than men with non-viscous semen. The expression of BAX, CASPASE-3 and CASPASE-9 genes in men with hyperviscous semen was significantly increased by 1.39-fold (P=0.041), 1.47-fold (P=0.046), 1.29-fold (P=0.048), respectively, as compared with the infertile subjects without hyperviscous semen. However, BCL2 expression in infertile men without hyperviscous semen was higher compared to those with hyperviscous semen (1.36-fold, P=0.044).

CONCLUSION

Hyperviscous semen is markedly associated with depletion of seminal plasma antioxidants, sperm membrane lipid peroxidation, DNA and protein oxidation, and sperm apoptosis. Antioxidant therapy might be considered as a valuable strategy to protect sperm cells against oxidative damage in cases with seminal fluid hyperviscosity.

Involvement of dopamine D2 -like receptors in the antiepileptogenic effects of deep brain stimulation during kindling in rats

AIMS

Deep brain electrical stimulation (DBS), as a potential therapy for drug resistive epileptic patients, has inhibitory action on epileptogenesis. In the present investigation, the role of dopamine D₂ -like receptors in the antiepileptogenic action of DBS was studied.

METHODS

Seizures were induced in adult rats by stimulating the perforant path in a semi-rapid kindling method. Five minutes after the last kindling stimulation, daily DBS was applied to the perforant path at the pattern of low frequency stimulation (LFS; 1 Hz; pulse duration: 0.1 ms; intensity: 50-150 μA; 4 trains of 200 pulses at 5 min intervals). Sulpiride (10 μg/1 μl, i.c.v.), a selective dopamine D₂ -like receptor antagonist, was administered prior to the daily LFS application.

RESULTS

Kindling stimulations increased cumulative daily behavioral seizure stages, daily afterdischarge duration (dADD), and population spike amplitude (PS) in dentate gyrus following perforant path stimulation, while applying LFS decreased the kindled seizures' parameters. In addition, kindling potentiated the early (at 10-50 ms inter-pulse interval) and late (at 150-1000 ms inter-pulse interval) paired-pulse inhibition and decreased the paired-pulse facilitation (at 70-100 ms inter-pulse interval). These effects were also inhibited by applying LFS. All inhibitory effects of LFS on kindling procedure were prevented by sulpiride administration.

CONCLUSION

These data may suggest that LFS exerts its preventive effect on kindling development, at least partly, through the receptors on which sulpiride acts which are mainly dopamine D₂ -like (including D₂ , D₃ , and D₄ ) receptors.

Anti-apoptotic properties of N-Acetyl cysteine and its effects on of Liver X receptor and Sirtuin 1 expression in the liver of rats exposed to Lead

BACKGROUND

This study aimed to evaluate the expression of Liver X receptor (Lxr), Sirtuin 1 (Sirt1), apoptotic-related genes, and the protective role of N-acetylcysteine (NAC) in the liver of rats treated with Lead (Pb).

METHODS

Rats were randomly divided into 5 groups, including G1 (control), G2 (single dose of Pb), G3 (continuous dose of Pb), G4 (single dose of Pb + NAC), and G5 (continuous dose of Pb + NAC). Lipid profiles and liver specific enzymes were assessed. Expression of Lxr, Sirt1, Bax and Caspase-3 genes was considered using RT-PCR.

RESULTS

Exposure to Pb caused a significant accumulation of Pb in the blood and liver tissue, increase in serum AST, ALT and ALP enzymes, as well as lipid profiles. Chronic exposure to Pb caused a significant decrease in Lxr (3.15-fold; p < 0.001) and Sirt1 (2.78-fold; p = 0.009), but significant increase in expression of Bax (4.49-fold; p < 0.001) and Caspase-3 (4.10-fold; p < 0.001) genes when compared to the control. Combined therapy with Pb + NAC in rats caused a significant decrease in AST, ALT and ALP values (28.93%, 20.80% and 28.86%, respectively) in the blood as compared to rats treated with Pb alone. Co-treated with Pb + NAC significantly increased the expression of Lxr (1.72-fold; p = 0.043) and Sirt1 (2.45-fold; p = 0.008), but decreased the expression of Bax (1.96-fold; p = 0.03) and Caspase 3 (2.22-fold; p = 0.029) genes when compared to rats treated with Pb alone.

CONCLUSION

Chronic exposure to Pb is strongly associated with accumulation of Pb in the blood and liver, hepatic cells apoptosis, down-expression of Lxr and Sirt1 genes and consequently liver injury and abnormal lipid profiles. NAC reversed the Pb-induced toxicity on the liver tissue.

Dual function of Selenium nanoparticles: Inhibition or induction of lysozyme amyloid aggregation and evaluation of their cell based cytotoxicity

Aberrant protein aggregation and the formation of amyloid deposits are associated with numerous neuro- and non-neurodegenerative disorders. Thus, one potential strategy is to eliminate these deposits by halting amyloid aggregation. Selenium nanoparticles (Se-NPs) have great potential in biomedicine for various therapeutic and diagnostic purposes and also have the ability to inhibit amyloid fibrillation. Herein, Hen Egg White Lysozyme (HEWL) was chosen as a protein model, and rod-like Se-NPs with diameters ranging from 90 to 120 nm were synthesized and the influence of shape and concentration of the particles on HEWL fibrillation was investigated. The effect of the nanoparticles on HEWL amyloid formation was analyzed using thioflavin T and Congo red binding assays, atomic force microscopy, and cytotoxicity assays. In the present study, it has been observed that these particles have a dual function in various concentrations. Using lower concentrations of Se-NPs ranging from 3-30 μg/ml, the Thioflavin T (ThT) fluorescence intensity decreased significantly by 60%, with an increased lag time compared to that of the control. While HEWL fibrillation substantially increased upon co-incubation with a higher concentration of these particles (300-2400μg/ml), and these results were verified by AFM, Congo red, and MTT assay. We showed that inhibitory or inductive influences of Se-NPs on the hen egg-white lysozyme (HEWL) amyloid aggregation are achieved via different independent mechanisms. These results demonstrate that dual-activity of Se-NPs might be a valuable targeting system for inhibiting amyloid aggregation, and thus, may play a useful role in new therapeutic and diagnostic strategies for amyloid-related disorders.

Serotonergic Modulation of Orientation Tuning of Neurons in Primary Visual Cortex of Anesthetized Mice

Introduction: Sensory processing is profoundly regulated by brain neuromodulatory systems. One of the main neuromodulators is serotonin which influences higher cognitive functions such as different aspects of perceptual processing. So, malfunction in the serotonergic system may lead to visual illusion in psychiatric disorders such as autism and schizophrenia. In this work, we examined the serotonergic modulation of visual responses of neurons to stimulus orientation in the primary visual cortex. Methods: Eight-weeks old naive mice were anesthetized and craniotomy was done on the region of interest in primary visual cortex. Spontaneous and visual-evoked activities of neurons were recorded before and during the electrical stimulation of dorsal raphe nucleus using in vivo whole-cell patch-clamp recording. Square-wave grating of 12 orientations was presented. Data was analyzed and Wilcoxon signed-rank test, used in order to compare the data of two conditions that belong to the same neurons, with or without electrical stimulation. Results: The serotonergic system changed orientation tuning of about 60 % recorded neurons by decreasing the mean firing rate in two independent visual response components: gain and baseline response. It also increased mean firing rate in a small number of neurons (about 20%). Beyond that, it left the preferred orientation and sensitivity of neurons unchanged. Conclusion: However, serotonergic modulation showed a bi-directional effect; it seems to cause predominately divisive and subtractive decreases in the visual responses of the neurons in the primary visual cortex that can modify the balance between internal and external sensory signals and result in disorders.

Coulomb drag in metal monochalcogenides double-layer structures with Mexican-hat band dispersions

We theoretically study the Coulomb drag resistivity and plasmon modes behavior for a system composed of two parallelp-type doped GaS monolayers with Mexican-hat valence energy band using the Boltzmann transport theory formalism. We investigate the effect of temperature,T, carrier density,p, and layer separation,d, on the plasmon modes and drag resistivity within the energy-independent scattering time approximation. Our results show that the density dependence of plasmon modes can be approximated byp^0.5. Also, the calculations suggest ad^0.2and ad^0.1dependencies for the acoustic and optical plasmon energies, respectively. Interestingly, we obtain that the behavior of drag resistivity in the double-layer metal monochalcogenides swings between the behavior of a double-quantum well system with parabolic dispersion and that of a double-quantum wire structure with a large carrier density of states. In particular, the transresistivity value reduces exponentially with increasing the distance between layers. Furthermore, the drag resistivity changes asT²/p⁴(T^2.8/p^4.5) at low (intermediate) temperatures. Finally, we compare the drag resistivity as a function of temperature for GaS with other Mexican-hat materials including GaSe and InSe and find that it adopts higher values when the metal monochalcogenide has smaller Mexican-hat height.

Genetic risk score associations for myocardial infarction are comparable in persons with and without rheumatoid arthritis: the population-based HUNT study

Persons with rheumatoid arthritis (RA) have increased risk of myocardial infarction (MI). Overlapping associations with MI of weighted genetic risk scores (wGRS) for coronary artery disease (CAD) and RA is unknown in a population-based setting. Data from the prospective Nord-Trøndelag Health Study (HUNT2: 1995–1997 and HUNT3: 2006–2008) were used. wGRS added each participant’s carriage of all risk variants weighted by the coefficient from published association studies. Published wGRS for CAD and RA were analysed in Cox regression with MI as outcome, age as analysis time, and censoring at the first MI, death, or 31.12.2017. 2609 of 61,465 participants developed MI during follow-up (mean 17.7 years). The best-fitting wGRS for CAD and RA included 157 and 27 single-nucleotide polymorphisms, respectively. In multivariable analysis including traditional CAD risk factors, the CAD wGRS was associated with MI [hazard ratio = 1.23 (95% CI 1.18–1.27) for each SD increase, p < 0.0001] in RA patients (n = 433) and controls. The RA wGRS was not significant (p = 0.06). Independently from traditional risk factors, a CAD wGRS was significantly associated with the risk for MI in RA patients and controls, whereas an RA wGRS was not. The captured genetic risk for RA contributed little to the risk of MI.

Effects in broiler hens of genetic lines differing in fertility, biotin supplementation, and age on relative abundance of oviductal transforming growth factor-β and carbonic anhydrase mRNA transcripts

There was evaluation of effects of biotin administration on oviductal abundance of transforming growth factor-β (TGF-β) and carbonic anhydrase (CA) mRNA transcript in younger and older broiler hens of relatively lesser and greater fertility lines. Additionally, effects of biotin supplementation on attenuation of age-related subfertility were evaluated. Hens from the relatively greater (Line D, n = 60) and lesser (Line B, n = 60) fertility rate line were randomly assigned to three treatment groups. Biotin was not or was administered in drinking water from 30 to 33 (younger age) and 53 to 56 (older age) wk of age to have access to no biotin (T₀), or 0.3 (T₁), or 0.45 (T₂) mg/L of biotin. There was assessment the relative oviductal abundances of TGF-β and CA mRNA transcript abundances. Supplemental biotin and age had no effect on the relative abundance of oviductal TGF-β mRNA transcript in hens of Line D. There, however, was a ten-fold greater abundance of TGF-β in hens of the T₀ group of Line B compared with Line D. Relative abundance of TGF-β mRNA transcript was greater in younger hens of Line B; however, biotin supplementation of older hens of the T₂ group of Line B resulted in a similar TGF-β abundance to that of younger hens. Inconstant with the TGF-β abundance, CA abundance in hens of Line B was not affected by supplemental biotin or bird age. Overall, differences in TGF-β or CA abundances did not affect fertility of broiler hens.

High prevalence of SCC mec-associated Phenol-soluble modulin gene in clinical isolates of methicillin-resistant. Staphylococcus aureus

INTRODUCTION

We aimed to determine the distribution of Phenol-soluble modulin-mec (psm-mec) gene and its relationship with biofilm formation in clinical methicillin-resistant S. aureus (MRSA).

METHODS

In a descriptive study, a total of 94 cefoxitin-resistant S. aureus isolates were collected from patients and tested for antibiotic susceptibility testing, multiplex polymerase chain reaction (MPCR) for detection of mecA and pvl genes, PCR for detection of psm-mec gene and SCCmec typing of psm-mec and pvl-positive isolates. Furthermore, isolates were tested by microtiter plate method for biofilm formation assay.

RESULTS

Multiplex PCR for detection of mecA and pvl genes was performed for all cefoxitin-resistant isolates. The mecA gene was found in 92 (97.9%) isolates but none of the isolates carried the pvl gene. Sixty-five (69.1%) isolates harbored psm-mec genes and 95.4% of these isolates belong to SCCmec type III. Statistical analysis showed a significant difference between the presence or absence of psm-mec gene and biofilm production (P<0.001).

CONCLUSION

In this study, more than half of the MRSA strains harbored psm-mec gene and almost one-fifth of them produced strong biofilm. Since the strains with strong biofilm formation have more antibiotic resistance and cause the long-lasting infection, for the suitable treatment of hospitalized patients with this kind of MRSA strains, we should be paid more attention to these strains.

Biofilm-producing ability of Staphylococcus spp isolated from different foodstuff products

BACKGROUND

In recent times, microbial-biofilm contamination has attracted considerable attention to the food industry. Pathogenic microorganisms can attach to food surfaces, grow on them, and form biofilm that cause an increase in the food safety risk. The mechanisms of biofilm formation have become an important issue in the food-processing industry, therefore, the aim of this study is to determine the biofilm formation and profiles of genes involved in biofilm production of staphylococci isolated from various foodstuff products.

MATERIAL AND METHODS

This cross-sectional study was conducted at some grocery stores and confectionaries from September 2015 to October 2016 in different areas of Isfahan, Iran. Staphylococcus spp were isolated from different foodstuff samples including sweet pastries, cakes and similar baked goods, dairy products such as cheese and yogurt, meat products such as sausages, and hamburgers. Standard microbiological methods were used for identification of Staphylococcus spp isolates. Antibiotic susceptibility pattern was determined by the disc diffusion method and icaA/icaD genes have been investigated as PCR target because of their role in the expression of intercellular adhesions involved in biofilm formation by S. aureus.

RESULTS

From a total of 194 different foodstuffs samples, 84 Staphylococcus spp were isolated. Out of the 84 Staphylococcus isolates, 95.2% (80/84) were positive to the ability of biofilm formation. Overall, 35.7% (30/84) and 26.2% (22/84) of Staphylococcus spp isolates were positive for icaA and icaD genes, respectively.

CONCLUSION

The results of the present study indicate that the remarkable rate of biofilm formation with the emergence of antibiotic resistance still remains a significant risk for the food safety, especially in foodstuff samples.

Comparison of methods to construct a genetic risk score for prediction of rheumatoid arthritis in the population-based Nord-Trøndelag Health Study, Norway

Objectives

To evaluate selection methods among published single-nucleotide polymorphisms (SNPs) associated with RA to construct predictive genetic risk scores (GRSs) in a population-based setting.

Methods

The Nord-Trøndelag Health (HUNT) Study is a prospective cohort study among the whole adult population of northern Trøndelag, Norway. Participants in HUNT2 (1995–1997) and HUNT3 (2006–2008) were included (489 RA cases, 61 584 controls). The initial SNP selection from relevant genome-wide studies included 269 SNPs from 30 studies. Following different selection criteria, SNPs were weighted by published odds ratios. The sum of each person’s carriage of all weighted susceptibility variants was calculated for each GRS.

Results

The best-fitting risk score included 27 SNPs [weighted genetic risk score 27 (wGRS27)] and was identified using P-value selection criterion ≤5 × 10−8, the largest possible SNP selection without high linkage disequilibrium (r2 &lt; 0.8), and lasso regression to select for positive coefficients. In a logistic regression model adjusted for gender, age and ever smoking, wGRS27 was associated with RA [odds ratio 1.86 (95% CI 1.71, 2.04) for each s.d. increase, P &lt; 0.001]. The AUC was 0.76 (95% CI 0.74, 0.78). The positive and negative predictive values were 1.6% and 99.7%, respectively, and the positive predictive value was not improved in sensitivity analyses subselecting participants to illustrate settings with increased RA prevalences. Other schemes selected more SNPs but resulted in GRSs with lower predictive ability.

Conclusion

Constructing a wGRS based on a smaller selection of informative SNPs improved predictive ability. Even with a relatively high AUC, the low PPV illustrates that there was a large overlap in risk variants among RA patients and controls, precluding clinical usefulness.

Evaluation of testis hormonal and histopathological alterations in type I and type II diabetic rats

BACKGROUND

Diabetes is a devastating metabolic disease that causes long-term damage to various organs. An important leading complication of diabetes is a degenerative effect on the reproductive system including infertility and gonadal dysfunction. This study aimed to evaluate the effects of experimental type I and II diabetes on the levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone.

METHODS

Male Wistar rats were randomly divided into four separate groups: (1) type I diabetes (T1DM), (2) type II diabetes (T2DM), (3) cetrorelix acetate-treated nondiabetic control group, and (4) normal untreated group (n = 6). T1DM was experimentally induced by a single injection of alloxan (135 mg/kg) while T2DM was induced by feeding the animals with drinking water enriched with fructose (10%). Cetrorelix acetate (100 mg/kg, intraperitoneal for 1 week) treatment group was used as a positive control. All rats were killed and blood and testes were collected after 8 weeks of the study. The effects of induced diabetes on the levels of blood glucose and insulin were assessed. The levels of sex hormones and insulin were determined by radioimmunoassay. Histological staining was used to check abnormal patterns of testicular morphology, the diameter of seminiferous tubules, testicular diameter, and germinal layer thickness.

RESULTS

A significant reduction in the testosterone, FSH, and LH levels were observed in T1DM, T2DM, and also in cetrorelix acetate-treated groups. Analysis of testicular histology sections revealed significantly reduced thickness of cell layer in T1DM and cetrorelix acetate-treated groups compared with the T2DM group. In T2DM, the cell numbers, the thickness of cell layer, the diameter of seminiferous tubules, and weight of testicles were slightly increased. In contrast, total tubules of empty seminiferous increased significantly in T1D and cetrorelix treated groups compared with the control group.

CONCLUSION

Overall, diabetes can induce hypothalamus-pituitary-gonad axis dysfunction, affects hormonal secretion, and causes histological damage to testes, collectively leading to deleterious effects on male fertility.

Primary ovarian insufficiency with t(5;13): a case report and literature review on disrupted genes

OBJECTIVES

To report a woman with primary ovarian insufficiency (POI) with reciprocal translocation between chromosomes 5 and 13.

METHODS

Chromosomal analysis (G-banding) of a 39-year-old woman with elevated gonadotropin levels and secondary amenorrhea and review of the literature with a special focus on disrupted genes at the reported breakpoints.

RESULTS

A reciprocal translocation between the long arms of chromosomes 5 and 13 was identified in the patient (46,XX,t(5;13)(q13;q14)). Investigation of the breakpoints revealed that the 13q14.1 region encompasses FOXO1 (forkhead box 1) gene, which has an important role in granulosa cell function and follicle maturation.

CONCLUSIONS

Autosomal translocations are rare in women with POI. We have reported the first case of a de novo reciprocal translocation involving chromosomes 5 and 13 in a POI patient. As one of the breakpoints encompasses the FOXO1 gene, it seems that disruption of this gene can be the cause of POI in this patient. This provides further evidence on the role of autosomal translocations in disrupting POI-associated genes. Therefore, concentrating on the genes at the breakpoints will be helpful to delineate the new biological pathways or genes involved in POI pathogenesis.

Comprehensive mutational analysis of primary and relapse acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is a subtype of myeloid leukemia characterized by differentiation block at the promyelocyte stage. Besides the presence of chromosomal rearrangement t(15;17), leading to the formation of PML-RARA (promyelocytic leukemia-retinoic acid receptor alpha) fusion, other genetic alterations have also been implicated in APL. Here, we performed comprehensive mutational analysis of primary and relapse APL to identify somatic alterations, which cooperate with PML-RARA in the pathogenesis of APL. We explored the mutational landscape using whole-exome (n=12) and subsequent targeted sequencing of 398 genes in 153 primary and 69 relapse APL. Both primary and relapse APL harbored an average of eight non-silent somatic mutations per exome. We observed recurrent alterations of FLT3, WT1, NRAS and KRAS in the newly diagnosed APL, whereas mutations in other genes commonly mutated in myeloid leukemia were rarely detected. The molecular signature of APL relapse was characterized by emergence of frequent mutations in PML and RARA genes. Our sequencing data also demonstrates incidence of loss-of-function mutations in previously unidentified genes, ARID1B and ARID1A, both of which encode for key components of the SWI/SNF complex. We show that knockdown of ARID1B in APL cell line, NB4, results in large-scale activation of gene expression and reduced in vitro differentiation potential.

The Effect of Formation of Titanium Nitride Thin Film on Surface Characteristics of Titanium by Nitrogen Ion Implantation

Titanium is used widely for applications that involve low weight and require suitable mechanical, biomedical and other desirable properties. In this paper, the effect of nitrogen ion implantation on surface structure and resistance against titanium corrosion and achievement of the best conditions for titanium nitride formation is investigated. For these experiments nitrogen ions with an energy of 30 keV and doses of 1 × 1018 to 5 × 1018 ion cm−2 were used. X-ray diffraction was performed for metallic analysis and investigation of new structures created by nitrogen ion implantation. Roughness variations before and after implantation were observed by atomic force microscopy. Corrosion analysis apparatus is used for comparison of resistance against titanium corrosion before and after ion implantation. Results show that nitrogen ion implantation has a substantial effect on resistance improvement against titanium corrosion. The surface morphology of the samples after corrosion testing is investigated using scanning electron microscopy. It is shown that the more important factor will control the final corrosion speed. In doses lower than 2×1018 ion cm−2, the roughness effect is most important, and in higher does, TiN phase formation is dominant.

MELATONIN ALLEVIATES BLEOMYCIN-INDUCED PULMONARY FIBROSIS IN MICE

Pulmonary fibrosis occurs as a common end-stage sequela of a number of acute and chronic lung diseases. Eicosanoids exert crucial roles in inflammatory processes pertinent to fibrogenesis induction, however, the role of cyclooxygenase 2 (COX-2) is not fully elucidated in most pulmonary fibrosis related-disorders. Recently, melatonin (MLN) has been introduced as an effective immuno-modulator and anti-oxidant agent. The present study aimed to investigate the effect of MLN on COX-2 expression in idiopathic pulmonary fibrosis (IPF). Animals were divided into five groups, including: 1) saline control, 2) 1% ethanol control, 3) MLN control, 4) bleomycin (BLM), in which mice were injected with BLM (15 mg/kg, i.p.) two times per week for four weeks, and 5) BLM+MLN, in which MLN was given to mice (10 mg/kg, i.p.) 30 minutes prior to BLM injections for four weeks. MLN administration significantly reduced body weight loss (P<0.05), the rate of mortality, edema formation, lung injury, COX-2 expression (P>0.05), interstitial tissue percentage volume (P<0.05), and also increased the alveolar space percentage volume. MLN attenuated the BLM-induced lung injury responses such as collagen accumulation and airway dysfunction in mice. Finally, histological evidence supported the ability of MLN to inhibit COX-2 expression. Thus, it may serve as a novel potential therapeutic agent for IPF.

Sustained reduction of alloantibody secreting plasma cells and donor specific antibody with proteasome inhibition in mice

The long-lived plasma cells, which develop after alloantigen sensitization, produce donor specific alloantibodies (DSAs) that generate a positive serum cross-match and preclude transplantation. Bortezomib, a proteasome inhibitor, is being investigated in clinical desensitization protocols, however preclinical studies in a transplant model are nonexistent. We hypothesized that sustained treatment with only a proteasome inhibitor would eliminate plasma cells and reduce DSA over time. Cardiac allografts were transplanted into murine recipients. Eight weeks after allograft rejection the proteasome inhibitor, bortezomib, was injected intravenously twice weekly for 60 days. Serum alloantibody responses were assayed using flow cross-match. Total and alloreactive plasma cell numbers were enumerated using flow cytometry and ELISPOT. All recipients of cardiac allografts rejected their graft promptly within 16 days and demonstrated alloantibody by flow cross-match. DSA was sustained in the control mice while mice treated with bortezomib had sustained elimination of DSA and a marked reduction in plasma cell population. Also, bortezomib was associated with an increased level of BLyS. Within a murine model, proteasome inhibition can eliminate alloantibody secreting plasma cells, and reduce alloantibody. Cessation of bortezomib is not associated with return of DSA.

A comparative study on the effects of type I and type II diabetes on learning and memory deficit and hippocampal neuronal loss in rat

AIM

In addition to learning and memory impairments, diabetes may also brings about neuronal loss in different regions of the brain specially hippocampus. In this line, the present study was conducted to investigate the effects of type I (T1D) and type II (T2D) diabetes on cognitive function and hippocampal neuronal density in rat.

METHODS

Three groups of male Wistar rats (N.=6) were regarded as control, T1D and T2D. T1D was induced by 60 mg/kg body weight of STZ injection and T2D by 10% fructose treatment through drinking water. Two months after the induction of both types of diabetes, learning abilities and memory retention of animals were measured using Morris Water Maze and shuttle box. All animals were perfused afterwards and their brains processed for stereological examination of hippocampal neuronal density.

RESULTS

In parallel to significant decrease in learning and memory scores, T1D showed a meaningful reduction in hippocampal neuronal density, when compared to control group. In T2D, the reductions of cognitive scores as well as hippocampal neuronal density were not significant, when compared to control and T1D.

CONCLUSION

Although both types of diabetes led to neuronal loss and spatial learning and memory dysfunction, these abnormalities were more obvious in T1D, while they are probably age-related and duration-dependent in T2D.

The expression of p38, ERK1 and Bax proteins has increased during the treatment of newly diagnosed acute promyelocytic leukemia with arsenic trioxide

BACKGROUND

Promising reports exist regarding the use of arsenic trioxide (ATO) as first-line treatment in acute promyelocytic leukemia (APL). Although the in vitro effect of ATO is extensively studied, the in vivo mechanism(s) of ATO action is mostly unknown.

PATIENTS AND METHODS

Newly diagnosed APL patients were involved and received ATO (0.15 mg.kg/day) for 28 days as induction followed by consolidation therapy. Bone marrow (BM) aspirates were obtained on days 0, 14 and 28 of treatment for further molecular studies. Clinical findings and white blood cell counts were recorded as well.

RESULTS

Complete remission was observed in 17 (85%) patients with the median duration of 28 days (18-38) and cumulative dosage of median 280 mg (180-350). Hyperleukocytosis and APL differentiation syndrome (63%), gastrointestinal disorders (30%), liver enzyme elevation and night sweating (50%) were the most prevalent side-effects. The expression of Bax, ERK1 and p38 proteins and caspase-3 activity increased significantly in promyelocytes of BM aspirates at days 14 and 28 of induction therapy.

CONCLUSION(S)

These findings point toward the role of p38 and Bax in the induction of apoptosis, which was confirmed by increase in caspase-3 activity. However, the increase in ERK1 expression with regard to leukocytosis could translate to a proliferative/differentiation effect.

Antimicrobial susceptibility pattern of microorganisms involved in the pathogenesis of surgical site infection (SSI); A 1 year of surveillance

The aim of this study is to identify the antibiotic sensitivity pattern of pathogens involved in the process of surgical site infection, in surgical wards. Changes made in the pattern of antibiotic use will result in different microorganism susceptibility patterns, which needs correct determination for precise empiric antibiotic therapy. One thousand patients (62% men and 38% women, 18- 74-years-old, with mean age 43 +/- 8)) who underwent surgical treatment, in Alzahra University Hospital, Isfahan University of Medicine, Isfahan, Iran, were studied from 2005 to 2006. Surgical wound infections, based on the reported criteria, were aspirated for culturing within 1 plus gram staining of prepared smears. Minimum Inhibitory Concentrations (MICs) were determined for samples and all derived data were compared by SPSS 13 and WHO net 5 software. The prevalence of SSI was 13.3% with 150 positive cultures, totally. Of 150 bacteria, isolated from surgical site infections Staphylococcus aureus had most frequency (43%). Resistance of isolated organisms was 41.7% in amikacin, 65 and 78.6% in ceftazidime, 85.7% in ceftriaxone, 61.5% in ciprofloxacin, 78.8% in gentamicine, 6.4% in imipenem, 13% in meropenem and 70.6% in trimethoprim/sulfamethoxazole, respectively. 78.9% of Staphylococcus aureus isolates were MRSA and vancomycine was the most effective antibiotic without any resistance. Among 10 isolates of coagulase negative Staphylococcus, no vancomycine resistance was seen, but in contrast all cases were resistant to oxacillin. The most common gram negative organism was Klebsiella (18 isolates) in which 100 and 80% were sensitive to imipenem and meropenem, respectively. Seventeen cases were E. coli, in which the most sensitivity was to meropenem (80%) and imipenem (77.8%). Thirteen cases of Pseudomonas were detected, in which 16.7% were resistant to imipenem and 8.3% to meropenem. Our results demonstrated that the total antibiotic resistance is increasing among SSIs, with an up sloping pattern, which will contact with a constant empiric antibiotic therapy. So, precise up to date antibiogram tantalize us toward balancing the rate of total antibiotic resistance to SSIs.

First-line treatment of acute promyelocytic leukemia with arsenic trioxide without ATRA and chemotherapy

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Background: Standard treatment of APL is ATRA plus chemotherapy but Arsenic Trioxide (ATO) is most potent single agent against APL cells. Role of ATO in first line therapy of APL needs to clarify. Methods: Between may 2000 and September 2006,we treated 141 new cases of APL(Median age 28±12.8 y/o min=11,max=71) by 2 hours iv infusion of 0.15mg/kg ATO until complete remission. Trial approved by IRB and consent form obtained. Diagnosis was by clinical and morphologic characteristics and confirmed by cytogenetic and RT-PCR for detection of t(15,17) and presence of PML-RARa. After complete remission patients received consolidation by 28 days infusion of ATO for one or four courses.(one consolidation one month after CR and for some patients second, third and forth consolidations one month after first one and two another , one year and two year after CR) Results: : complete remission observed in 121 cases(85.8%) and early mortality rate was14.9%(most common cause of early mortality was APL syndrome,61.9%).Median follow up was 28 months. For patients who achieve to complete remission,one, two and three year disease free survival were 95.6%± 2%, 76.9±4% and 57± 6%,respectively. Many relapsed patients salvaged again with ATO alone so, two and three years overall survival for this cohort was 95.6%±2% and 83.7%±4%. Increasing number of consolidation from one to four couldn’t increase DFS or OS in one and two years after CR. Conclusions: ATO is effective in treatment of new cases of APL. Introduction of ATO in first line treatment of APL(with or without ATRA plus chemotherapy) needs a multi center randomized clinical trial.

No significant financial relationships to disclose.

Risk factors for early mortality, relapse and overall survival in new cases of APL treated by arsenic trioxide

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Background: There are several known risk factors for APL treatment by ATRA and chemotherapy, but risk factors for new cases of APL treated by Arsenic Trioxide are unknown. Methods: Between May 2000 and September 2006, we treated 141 new cases of APL (Median age 28±12.8 y/o min=11, max=71) by 2 hours iv infusion of 0.15mg/kg ATO until complete remission. Trial approved by IRB and consent form obtained. Diagnosis was by clinical and morphologic characteristics and confirmed by cytogenetic and RT-PCR for detection of t(15,17) and presence of PML-RARa. After complete remission patients received consolidation by 28 days infusion of ATO for one or four courses. Known risk factors for APL treatment outcome (including PML-RARa isoforms, presence of MRD during follow up and WBC count at presentation analyzed for early mortality, relapse rate, DFS and OS. Results: Complete remission observed in 121 cases (85.8%) and early mortality rate was 14.9%. short isoform of detected in 36% of patients and 18% presented by WBC more than 10,000/μl. For early mortality, APL differentiation syndrome during treatment and WBC count more than 10,000/μl were risk factors. (P<0.001 and p=0.011 respectively) For DFS only predicting factor for relapse was detection of MRD (by nested PCR or by real time PCR) during follow up (P=0.05). For prediction of OS, again only risk factor was detection of MRD(P<0.0001). Conclusions: Although WBC count before treatment and APL differentiation syndrome during treatment are risk factor for relapse, short isoform of APL is not a risk factor. After achieving to CR only risk factor is detection of MRD.

No significant financial relationships to disclose.

Real-time PCR analysis of PML-RARα in newly diagnosed acute promyelocytic leukaemia patients treated with arsenic trioxide as a front-line therapy

BACKGROUND

Recently, patients with acute promyelocytic leukaemia (APL) have experienced significant clinical gains after treatment with arsenic trioxide. However, the use of this agent as a front-line therapy for newly diagnosed patients is unclear.

PATIENTS AND METHODS

Of 95 newly diagnosed APL patients, 85 patients who achieved complete remission (CR) were sequentially evaluated during a 4-60 month period by conventional RT-PCR. A total of 30 patients (six relapsed and 24 in continued CR) were selected and monitored by quantitative real-time PCR (RQ-PCR) assay. The PML-RARalpha fusion transcripts values were normalised to every 10(6) copies of G6PDH transcripts (NQ).

RESULTS

RQ-PCR analyses showed a rapid rate of clearance of NQ levels during the courses of arsenic therapy. In the majority of patients in CR, the NQ levels were below 5 x 10(2) in peripheral blood (PB) samples. In all the relapsed cases with follow-up intervals of 1-6 months (median 3 months) clinical relapse was predictable by increasing NQ level above this threshold.

CONCLUSIONS

Our study highlights the usefulness of PB and the definition of threshold level for early prediction of relapse. The threshold level correlates well with risk of relapse; therefore, transcript ratio below the level should be regarded as a goal in the clinical management of this disease.

Quantitative analysis of PML-RARα in newly diagnosed acute promyelocytic leukemia patients treated with arsenic trioxide as a front-line therapy

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Background: Recently, patients with acute promyelocytic leukemia (APL) have experienced significant clinical gains after treatment with arsenic trioxide (As2O3). However, the potential role for use of this agent as a front-line therapy for newly diagnosed patients is unclear. Methods: From 95 patients with APL, 85 patients who achieved complete remission (CR) were sequentially evaluated during 4–60 months period of follow-up by conventional RT-PCR. A total of 30 patients (6 relapsed and 24 in continued long remission) were selected and monitored by quantitative real-time PCR (RQ-PCR) assay. Using ‘Hybridization Probes‘ technology, the expression of PML-RARα/G6PDH transcript ratio was analyzed in serial PB samples taken at different courses of disease and the results were compared with the clinical outcome. Results: More than 90% of patients obtained molecular remission, as determined by conventional RT-PCR in 1–3 months after start of arsenic therapy. RQ-PCR analyses showed a rapid rate of clearance of PML-RARα/G6PDH transcript level during the courses of arsenic therapy. In majority of the patients in CR the level of PML-RARα/ G6PDH ratio was always below 5×102 in PB samples. In all the relapsed cases with follow-up intervals of 1–6 months (median 3) clinical relapse was predictable by increasing transcript level above this threshold. Conclusions: Using a sensitive and quantitative method provided valuable information about effectiveness of arsenic as a front-line therapy in the management of newly diagnosed APL. Our study highlights the usefulness of PB and the definition of threshold level for early prediction of relapse. The threshold level correlates well with relapse risk; therefore, transcript ratio below the level should be regarded as a goal in the clinical management of this disease.

No significant financial relationships to disclose.

Treatment of acute promyelocytic leukemia with arsenic trioxide without ATRA and/or chemotherapy

INTRODUCTION

Arsenic trioxide is effective and approved for treatment of relapsed or refractory acute promyelocytic leukemia (APL) cases resistant to all-trans retinoic acid (ATRA), but its effect on new cases of APL is not clear.

MATERIALS AND METHODS

We studied 111 patients with APL. Arsenic trioxide was infused at 0.15 mg/kg daily dose, until complete remission was achieved. Then, after 28 days of rest, arsenic trioxide was infused daily for 28 days as consolidation therapy. We studied minimal residual disease (MRD) by semi-sensitive reverse transcription polymerase chain reaction (RT-PCR) on peripheral blood samples.

RESULTS

Complete remission was observed in 95 patients (85.6%). With the median (range) follow-up period of 16.5 (1-57) months, 1- and 2-year disease-free survival was 88.3% and 63.7%, respectively; 24 patients relapsed, 19 of whom achieved a second complete remission, again by arsenic trioxide. Third and fourth remissions were seen in some relapsed patients, again by arsenic trioxide. For patients in complete remission, 1- and 3-year survival was 95.5% and 87.6%, respectively. MRD was positive in four (8.3%) out of 48 cases during 1 year after remission induction; three of them relapsed clinically.

CONCLUSIONS

Arsenic trioxide is effective as first-line treatment for APL. Results of arsenic trioxide combination therapy with chemotherapy/ATRA requires further study.

Tracking alloreactive cell division in vivo

BACKGROUND

The study of alloimmune responses has been limited by a lack of assays that can track the behavior of alloreactive lymphocytes in vivo. Here we utilize an experimental system that allows the identification and study of alloreactive CD4+ lymphocytes responding to major histocompatibility antigens in vivo.

METHODS

Responder mouse lymphocytes were labeled with a fluorescein-based dye, adoptively transferred into irradiated allogeneic stimulator mice, and recovered at serial time points for analysis by flow cytometry.

RESULTS

Discrete generations of CD4+ responder lymphocytes proliferating specifically in response to allogeneic MHC class II were distinguished by fluorescein intensity. Successive division of alloreactive CD4+ lymphocytes was traced up to six generations after 60 hr.

CONCLUSIONS

This experimental system provides information on the division kinetics of alloreactive CD4+ cells. Other applications include immunophenotyping of alloreactive lymphocyte subsets. Further study of systems such as this will allow the detailed characterization of how alloimmune responses are initiated and proceed in vivo.

Cardiac allograft tolerance induced by intra-arterial infusion of recombinant adenoviral CTLA4Ig

BACKGROUND

Systemic administration of soluble recombinant fusion protein of cytotoxic T lymphocyte antigen 4 (CTLA4Ig) induces blockade of the CD28/B7 costimulatory pathway and promotes survival of allogeneic and xenogeneic grafts. We tested the efficacy of local expression of CTLA4Ig gene in the myocardium, induced by transduction with a recombinant adenovirus encoding the CTLA4Ig gene, on the survival of rat cardiac allografts.

METHODS

The donor hearts were perfused ex vivo with recombinant adenovirus encoding CTLA4Ig cDNA (AdCTLA4Ig) via intra-aorta coronary artery before transplantation. The distribution and duration of CTLA4Ig transgene expression in the myocardium was assessed by reverse transcriptase polymerase chain reaction (RT-PCR) or in situ RT-PCR after transplantation.

RESULTS

In situ RT-PCR demonstrated abundant expression of CTLA4Ig transgene in the endo-myocardium of AdCTLA4Ig-perfused cardiac grafts. Lewis and Brown Norway cardiac allografts transduced with AdCTLA4Ig survived indefinitely in nonimmunosuppressed Wistar Furth recipients. However, donor-strain skin grafts were rejected by long-term recipients of cardiac allografts, which also triggered the rejection of the primary heart grafts.

CONCLUSIONS

A single ex vivo intra-aortic infusion of recombinant adenovirus encoding the CTLA4Ig gene induced efficient transduction of the endo-myocardium and promoted the permanent survival of cardiac allografts in nonimmunosuppressed hosts. Despite the beneficial effect of local immunosuppression on cardiac allograft survival, the strategy failed to promote a state of donor-specific peripheral tolerance.

Cutting edge: alloimmune responses against major and minor histocompatibility antigens: distinct division kinetics and requirement for CD28 costimulation

Comparative study of alloimmune responses against major and minor histocompatibility Ags has been limited by the lack of suitable assays. Here, we use a bioassay that permits tracking of alloreactive CD4+ T cell populations as they proliferate in response to major or minor histocompatibility Ags in vivo. Division of alloreactive CD4+ T cells proceeded more rapidly in response to major histocompatibility Ags than minor Ags, although CD4+ T cells alloreactive to minor Ags had a similar capacity to divide successively up to eight times after stimulation. Allorecognition of minor histocompatibility Ags was highly dependent on CD28 costimulation, with the frequency of CD4+ T cells proliferating in response to minor Ags in the absence of CD28 costimulation reduced up to 20-fold. These findings highlight differences in signaling processes that lead to allorecognition of major and minor histocompatibility Ags and have implications on the design of interventions aimed at abrogating these responses.

Prevention of autoimmune recurrence and rejection by adenovirus-mediated CTLA4Ig gene transfer to the pancreatic graft in BB rat

Type 1 diabetes is the result of a selective destruction of pancreatic islets by autoreactive T-cells. Therefore, in the context of islet or pancreas transplantation, newly transplanted beta-cells are threatened by both recurrent autoimmune and alloimmune responses in recipients with type 1 diabetes. In the present study, using spontaneously diabetic BB rats, we demonstrate that whereas isolated islets are susceptible to autoimmune recurrence and rejection, pancreaticoduodenal grafts are resistant to these biological processes. This resistance is mediated by lymphohematopoietic cells transplanted with the graft, since inactivation of these passenger cells by irradiation uniformly rendered the pancreaticoduodenal grafts susceptible to recurrent autoimmunity. We further studied the impact of local immunomodulation on autoimmune recurrence and rejection by ex vivo adenovirus-mediated CTLA4Ig gene transfer to pancreaticoduodenal grafts. Syngeneic DR-BB pancreaticoduodenal grafts transduced with AdmCTLA4Ig were rescued from recurrent autoimmunity. In fully histoincompatible LEW-->BB transplants, in which rejection and recurrence should be able to act synergistically, AdmCTLA4Ig transduced LEW-pancreaticoduodenal allografts enjoyed markedly prolonged survival in diabetic BB recipients. In situ reverse transcription-polymerase chain reaction revealed that transferred CTLA4Ig gene was strongly expressed in both endocrine and exocrine tissues on day 3. These results indicate the potential utility of local CD28-B7 costimulatory blockade for prevention of alloimmune and autoimmune destruction of pancreatic grafts in type 1 diabetic hosts.

Utility of adenoviral-mediated Fas ligand gene transfer to modulate islet allograft survival

BACKGROUND

One of the best-defined mechanisms for the induction of apoptosis involves signaling via the cell surface molecule Fas, after binding of Fas ligand. Expression of Fas ligand is tightly regulated, being expressed primarily by T cells after activation, where it serves as a self-regulatory mechanism for immune responses. Fas ligand has also been found to be expressed constitutively at sites of immune privilege such as the testes and the anterior chamber of the eye. Recently, co-transplantation of Fas ligand-transfected myoblasts in association with islet cell allografts was shown to prolong islet allograft survival but only rarely led to indefinite graft survival. Graft rejection was associated with loss of Fas ligand on the myoblasts, suggesting that direct expression of the transgene on the islets might be more effective.

METHODS

A replication-defective adenoviral construct containing murine Fas ligand (Ad/MFL) was prepared by homologous recombination. NIH 3T3 cells, rodent splenocytes, and murine islets were infected with Ad/MFL and examined in vitro for functional murine Fas ligand expression. Survival of Ad/MFL-infected islets was subsequently evaluated in vivo in both syngeneic and allogeneic islet transplantation models.

RESULTS

Cell lines and islet allografts transfected with Ad/MFL expressed a functional Fas ligand, capable of inducing apoptosis (confirmed by three distinct assays for DNA fragmentation) in Fas+ targets, but not in Fas- controls. Furthermore, Ad/MFL was able to modify allogeneic immune responses in vitro, as addition of this virus, but not a control adenovirus, significantly reduced proliferation in a mixed lymphocyte reaction. Surprisingly, however, transplantation of islet allografts transfected with Ad/MFL resulted in long-term allograft survival in only 1 of 30 recipients. Moreover, adenoviral-mediated Fas ligand gene transfer was complicated by transient, dose-dependent islet dysfunction, perhaps contributing to the lack of long-term engraftment.

CONCLUSION

These data suggest that adenoviral-mediated Fas ligand expression may impair normal islet function in vivo, and indicate that alternative strategies for Fas ligand transgene delivery may be required in this setting.

Tolerance to experimental cardiac allografts produced by neonatal intrathymic injection of donor cells

Intrathymic inoculation of allogeneic cells after systemic administration of antilymphocyte serum in adult experimental animals has produced donor-specific tolerance to cardiac allografts. We investigated whether thymic injection of allogeneic cells without antilymphocyte serum in neonatal Lewis rats (day 1 of life) with immature immune systems also produced tolerance to cardiac grafts. Intrathymic or intraperitoneal injection of 5 x 10(7) Lewis (control) or Lewis-Brown Norway (allogeneic) spleen cells in Lewis neonates was followed by heterotopic cardiac transplantation using Lewis, Lewis-Brown Norway, or Wistar Furth (third-party allograft) hearts at 6 to 8 weeks of age. Graft survival was prolonged with both intraperitoneal and intrathymic allogeneic cells. Recipients of cells by the intrathymic route had longer graft survival, and 2 of 5 animals achieved permanent graft acceptance (longer than 100 days). As expected, Lewis isografts survived indefinitely, whereas third-party Wistar Furth allografts were rejected in the usual time frame. Intrathymic introduction of allogeneic cells in a neonatal recipient with an immature immune system can produce donor-specific tolerance to a subsequent graft without the need for a systemic immunosuppression regimen, even transiently.