Acoustically Driven Stark Effect in Transition Metal Dichalcogenide Monolayers

The Stark effect is one of the most efficient mechanisms to manipulate many-body states in nanostructured systems. In mono- and few-layer transition metal dichalcogenides, it has been successfully induced by optical and electric field means. Here, we tune the optical emission energies and dissociate excitonic states in MoSe2 monolayers employing the 220 MHz in-plane piezoelectric field carried by surface acoustic waves. We transfer the monolayers to high dielectric constant piezoelectric substrates, where the neutral exciton binding energy is reduced, allowing us to efficiently quench (above 90%) and red-shift the excitonic optical emissions. A model for the acoustically induced Stark effect yields neutral exciton and trion in-plane polarizabilities of 530 and 630 × 10-5 meV/(kV/cm)2, respectively, which are considerably larger than those reported for monolayers encapsulated in hexagonal boron nitride. Large in-plane polarizabilities are an attractive ingredient to manipulate and modulate multiexciton interactions in two-dimensional semiconductor nanostructures for optoelectronic applications. © 2021 The Authors. Published by American Chemical Society

Multicentre Italian study of SARS-CoV-2 infection in children and adolescents, preliminary data as at 10 April 2020

Data on features of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in children and adolescents are scarce. We report preliminary results of an Italian multicentre study comprising 168 laboratory-confirmed paediatric cases (median: 2.3 years, range: 1 day-17.7 years, 55.9% males), of which 67.9% were hospitalised and 19.6% had comorbidities. Fever was the most common symptom, gastrointestinal manifestations were frequent; two children required intensive care, five had seizures, 49 received experimental treatments and all recovered

Reduction in mortality with availability of antiretroviral therapy for children with perinatal HIV-1 infection. Italian Register for HIV Infection in Children and the Italian National AIDS Registry.

CONTEXT: Since the introduction of combined antiretroviral therapy, mortality rates in adults with human immunodeficiency virus type 1 (HIV-1) infection have decreased. However, little information is available outside the setting of controlled trials on survival of perinatally HIV-infected children treated with antiretroviral therapy. OBJECTIVE: To assess effect of availability of antiretroviral therapy on decreasing mortality in perinatally HIV-infected children. DESIGN: Population-based, multicenter longitudinal study involving data collected by the Italian Register for HIV Infection in Children. SETTING: A network of 106 pediatric clinical centers. SUBJECTS: A total of 1142 children born between November 1980 and December 1997 with perinatally acquired HIV infection with a median follow-up of 5.9 years. MAIN OUTCOME MEASURE: Time to HIV-related death calculated for birth cohort and calendar period and grouped by distribution of predominant type of antiretroviral therapy administered over time. RESULTS: Survival was longer in the 1996-1997 birth cohort (crude relative hazard [RH] of death, 0.39; 95% confidence interval [CI], 0.15-0.96) and 1996-1998 calendar period (crude RH of death, 0.65; 95% CI, 0.45-0.95) than in birth cohort and calendar period 1980-1995, but not when adjusted for maternal antiretroviral treatment during pregnancy and clinical condition at time of delivery, gestational age, and birth weight (adjusted RH of death, 0.55; 95% CI, 0.20-1.50, for birth cohort; and adjusted RH of death, 0.71, 95% CI, 0.43-1.16, for calendar period). In a multivariate model with 1980-1995 as comparison, the 1996-1997 birth cohort had an RH of 0.57 (95% CI, 0.22-1.47; P=.27) but RH for calendar period 1996-1998 was 0.63 (95% CI, 0.47-0.85; P<. 01). When the effects of birth cohort, calendar period, and type of antiretroviral therapy were evaluated simultaneously in the same model, the RH of death was not significantly different from 1.0 for the 1996-1997 birth cohort (P=.19) and calendar period 1996-1998 (P=. 83) suggesting a causal relationship between decreased risk of death and use of combination therapy. The RH of death in children receiving monotherapy or double or triple combination therapy was 0. 77 (95% CI, 0.55-1.08), 0.70 (95% CI, 0.42-1.17), and 0.29 (95% CI, 0.13-0.67), respectively, vs no antiretroviral therapy. CONCLUSION: Survival of perinatally HIV-infected children improved in 1996-1998 as a result of the introduction of combined antiretroviral therapie

Rapid disease progression in HIV-1 perinatally infected children born to mothers receiving zidovudine monotherapy during pregnancy. The Italian register for HIV Infection in Children.

OBJECTIVE: To investigate the outcome in children perinatally infected with HIV-1 whose mothers received zidovudine (ZDV) monotherapy in pregnancy. DESIGN: Observational retrospective study of a prospectively recruited cohort. SETTING: Italian Register for HIV Infection in Children. PATIENTS: A group of 216 children perinatally infected with HIV-1, born in 1992-1997 and derived prospectively from birth: 38 children had mothers receiving ZDV monotherapy and for 178 children the mothers received no antiretroviral treatment during pregnancy. MAIN OUTCOME MEASURES: The estimated probability of developing severe disease or severe immune suppression, survival probability [95% confidence interval (CI)] within 3 years, and the hazard ratio (95% CI), adjusted for year of birth, maternal clinical condition at delivery, birthweight and treatments (Pneumocystis carinii pneumonia chemoprophylaxis and/or antiretroviral therapy before the onset of severe disease, severe immune suppression or death) were compared. RESULTS: Comparison of HIV-1-infected children whose mothers were treated with ZDV with children whose mothers were not treated showed that the former group had a higher probability of developing severe disease [57.3% (95% CI 40.9-74.3) versus 37.2% (95% CI 30.0-45.4); log-rank test 7.83, P = 0.005; adjusted hazard ratio 1.8 (95% CI 1.1-3.1)] or severe immune suppression [53.9% (95% CI 36.3-73.5) versus 37.5% (95% CI 30.0-46.2); log-rank test 5.58, P = 0.018; adjusted hazard ratio 2.4, (95% CI: 1.3-4.3)] and a lower survival [72.2% (95% CI 50.4-85.7) versus 81.0% (95% CI 73.7-86.5); log-rank test 4.23, P = 0.039; adjusted hazard ratio of death 1.9 (95% CI 1.1-3.6)]. CONCLUSIONS: This epidemiological observation could stimulate virologic studies to elucidate whether this rapid progression depends on in utero infection or transmission of resistant virus. Findings may suggest a need to hasten HIV-1 diagnosis in infants of ZDV-treated mothers and undertake an aggressive antiretroviral therapy in those found to be infecte

The mode of delivery and the risk of vertical transmission of human immunodeficiency virus type 1 - A meta-analysis of 15 prospective cohort studies

Background To evaluate the relation between elective cesarean section and vertical transmission of human immunodeficiency virus type 1 (HIV-1), we performed a meta-analysis using data on individual patients from 15 prospective cohort studies. Methods North American and European studies of at least 100 mother-child pairs were included in the meta-analysis. Uniform definitions of modes of delivery were used. Elective cesarean sections were defined as those performed before onset of labor and rupture of membranes. Multivariate logistic-regression analysis was used to adjust for other factors known to be associated with vertical transmission. Results The primary analysis included data on 8533 mother-child pairs. After adjustment for receipt of antiretroviral therapy, maternal stage of disease, and infant birth weight, the likelihood of vertical transmission of HIV-1 was decreased by approximately 50 percent with elective cesarean section, as compared with other modes of delivery (adjusted odds ratio, 0.43; 95 percent confidence interval, 0.33 to 0.56). The results were similar when the study population was limited to those with rupture of membranes shortly before delivery. The likelihood of transmission was reduced by approximately 87 percent with both elective cesarean section and receipt of antiretroviral therapy during the prenatal, intrapartum, and neonatal periods, as compared with other modes of delivery and the absence of therapy (adjusted odds ratio, 0.13; 95 percent confidence interval, 0.09 to 0.19), Among mother-child pairs receiving antiretroviral therapy during the prenatal, intrapartum, and neonatal periods, rates of vertical transmission were 2.0 percent among the 196 mothers who underwent elective cesarean section and 7.3 percent among the 1255 mothers with other modes of delivery. Conclusions The results of this meta-analysis suggest that elective cesarean section reduces the risk of transmission of HIV-1 from mother to child independently of the effects of treatment with zidovudine. (N Engl J Med 1999;340:977-87.) (C)1999, Massachusetts Medical Society

Is the interruption of antiretroviral treatment during pregnancy an additional major risk factor for mother-to-child transmission of HIV type 1?

BACKGROUND: There is currently an experts' agreement discouraging interruption of antiretroviral treatment (ART) during the first trimester of pregnancy in women infected with human immunodeficiency virus type 1 (HIV-1). However, this recommendation is poorly supported by data. We evaluated the effects of discontinuing ART during pregnancy on the rate of mother-to-child transmission.METHODS: Logistic regression models were performed in a prospective cohort of 937 children who were perinatally exposed to HIV-1 to estimate adjusted odds ratios for confounding factors on mother-to-child transmission, including maternal interruption of ART.RESULTS: Among 937 pregnant women infected with HIV-1, ART was interrupted in 81 (8.6%) in the first trimester and in 11 (1.2%) in the third trimester. In the first trimester, the median time at suspension of ART was 6 weeks (interquartile range [IQR], 5-6 weeks) and the time without treatment was 8 weeks (IQR, 7-11 weeks). In the third trimester, the median time at suspension of ART was 32 weeks (IQR, 23-36 weeks) and the time without treatment was 6 weeks (IQR, 2-9 weeks). The plasma viral load was similar in women who had treatment interrupted in the first trimester and in those who did not have treatment interrupted. Overall, the rate of mother-to-child transmission in the whole cohort was 1.3% (95% confidence interval [CI], 0.7%-2.3%), whereas it was 4.9% (95% CI, 1.9%-13.2%) when ART was interrupted in the first trimester and 18.2% (95% CI, 4.5%-72.7%) when ART was interrupted in the third trimester. In the multiple logistic regression models, only interruption of ART during either the first or the third trimester, maternal mono- or double therapy, delivery by a mode other than elective cesarean delivery, and a viral load at delivery >4.78 log(10) copies/mL were independently associated with an increased rate of mother-to-child transmission.CONCLUSIONS: Discontinuing ART during pregnancy increases the rate of mother-to-child transmission of HIV-1, either when ART is stopped in the first trimester and subsequently restarted or when it is interrupted in the third trimester. This finding supports recommendations to continue ART in pregnant women who are already receiving treatment for their health

The mode of delivery and the risk of vertical transmission of human immunodeficiency virus type 1--a meta-analysis of 15 prospective cohort studies. The International Perinatal HIV Group.

To evaluate the relation between elective cesarean section and vertical transmission of human immunodeficiency virus type 1 (HIV-1), we performed a meta-analysis using data on individual patients from 15 prospective cohort studies. North American and European studies of at least 100 mother-child pairs were included in the meta-analysis. Uniform definitions of modes of delivery were used. Elective cesarean sections were defined as those performed before onset of labor and rupture of membranes. Multivariate logistic-regression analysis was used to adjust for other factors known to be associated with vertical transmission. The primary analysis included data on 8533 mother-child pairs. After adjustment for receipt of antiretroviral therapy, maternal stage of disease, and infant birth weight, the likelihood of vertical transmission of HIV-1 was decreased by approximately 50 percent with elective cesarean section, as compared with other modes of delivery (adjusted odds ratio, 0.43; 95 percent confidence interval, 0.33 to 0.56). The results were similar when the study population was limited to those with rupture of membranes shortly before delivery. The likelihood of transmission was reduced by approximately 87 percent with both elective cesarean section and receipt of antiretroviral therapy during the prenatal, intrapartum, and neonatal periods, as compared with other modes of delivery and the absence of therapy (adjusted odds ratio, 0.13; 95 percent confidence interval, 0.09 to 0.19). Among mother-child pairs receiving antiretroviral therapy during the prenatal, intrapartum, and neonatal periods, rates of vertical transmission were 2.0 percent among the 196 mothers who underwent elective cesarean section and 7.3 percent among the 1255 mothers with other modes of delivery. The results of this meta-analysis suggest that elective cesarean section reduces the risk of transmission of HIV-1 from mother to child independently of the effects of treatment with zidovudine