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Biomedical subjects

R Kohan

Publications and source records attributed to R Kohan.

At least 19 recordsLinked to original sources

Transfer of metformin into human milk.

AIMS/HYPOTHESIS: The aim of this study was to characterize the milk-to-plasma ratio and infant dose for metformin in breastfeeding women, and to measure plasma concentrations and assess any effects in their infants. We hypothesized that metformin used by mothers is safe for their breastfed infants. METHODS: Seven women taking metformin (median dose 1500 mg orally daily) and their infants were studied. Metformin concentrations in plasma and milk were measured by high performance liquid chromatography. Infant exposure was estimated as the product of estimated milk production rate and the average concentration of the drug in milk and also expressed as a percentage of the weight-normalized maternal dose. RESULTS: The mean milk-to-plasma ratio for metformin was 0.35 (95%CI 0.2-0.5). The mean of its average concentrations in milk over the dose interval was 0.27 mg/l (0.15-0.39 mg/l). The absolute infant dose averaged 0.04 mg x kg(-1) x day(-1) (0.02-0.06 mg x kg(-1) x day(-1)) and the mean relative infant dose was 0.28% (0.16-0.4%). Metformin was present in very low or undetectable concentrations in the plasma of four of the infants who were studied. No health problems were found in the six infants who were evaluated. CONCLUSIONS/INTERPRETATION: The concentrations of metformin in breast milk were generally low and the mean infant exposure to the drug was only 0.28% of the weight-normalized maternal dose. As this is well below the 10% level of concern for breastfeeding, and because the infants were healthy, we conclude that metformin use by breastfeeding mothers is safe. Nevertheless, each decision to breastfeed should be made after conducting a risk:benefit analysis for each mother and her infant.

Adult↗

Alpha-interferon therapy induces improvement of platelet counts in children with chronic idiopathic thrombocytopenic purpura.

PURPOSE: To investigate alpha-interferon (IFN) therapy for children with chronic idiopathic thrombocytopenic purpura (ITP). PATIENTS AND METHODS: Patients with refractory ITP lasting more than 12 months from diagnosis were included if they had platelet counts <50 x 10(9)/L and had received no treatment during the past month. Patients received IFN (3 x 10(6) U/m2 per dose), three times per week for 4 weeks; if partial (<150 x 10(9)/L) or no response was obtained, the same dose was continued for another 8 weeks. In patients with favorable response and subsequent decrease to pre-treatment values, an additional 4 weeks of treatment could be administered. RESULTS: Fourteen patients (ages 4-20 y) receiving 17 IFN courses were included. Mean initial platelet count was 29 +/- 15 x 10(9)/L. A significant increase was achieved during 14 of 17 courses (82.4%). All but two responses were transitory, and platelets returned to initial values after IFN discontinuation (mean 44 +/- 26 days). Considering the best response achieved by each patient, we observed: 1) 10 patients who achieved a sustained improvement of platelet count throughout the treatment period, decreasing to initial values after therapy was stopped; 2) one patient who achieved platelet count >150 x 10(9)/L, remaining with normal platelets at 18 months; 3) one patient who achieved platelet count >150 x 10(9)/L, remaining with platelets between 100 and 140 x 10(9)/L at 48 months; 4) one patient who had no response; and 5) one patient in whom therapy worsened the thrombocytopenia. A mild to moderate flu-like syndrome and a moderate decrease of the absolute neutrophil count were the only side effects observed. CONCLUSION: Interferon therapy induces a significant increase of platelet count and seems to be a valid alternative therapy to attempt the achievement of prolonged remission in refractory ITP, to defer splenectomy in younger children, or to improve platelet count before planned splenectomy.

Adolescent↗

Citalopram and demethylcitalopram in human milk; distribution, excretion and effects in breast fed infants.

AIMS: To characterize milk/plasma (M/P) ratio and infant dose, for citalopram and demethylcitalopram, in breast-feeding women taking citalopram for the treatment of depression, and to determine the plasma concentration and effects of these drugs in their infants. METHODS: Seven women (mean age 30.6 years) taking citalopram (median dose 0.36 mg kg(-1) day(-1)) and their infants (mean age 4.1 months) were studied. Citalopram and demethylcitalopram in plasma and milk were measured by high-performance liquid chromatography over a 24 h dose interval. Infant exposure was estimated (two separate methods) as the product of milk production rate and drug concentration in milk, normalized to body weight and expressed as a percentage of the weight-adjusted maternal dose. RESULTS: Mean M/PAUC values of 1.8 (range 1.2-3) and 1.8 (range 1.0-2.5) were calculated for citalopram and demethylcitalopram, respectively. The mean maximum concentrations of citalopram and demethylcitalopram in milk were 154 (95% CI, 102-207) microg l(-1) and 50 (23-77) microg l(-1). Depending on the method of calculation, mean infant exposure was 3.2 or 3.7% for citalopram and 1.2 or 1.4% for demethylcitalopram. Citalopram (2.0, 2.3 and 2.3 microg l(-1)) was detected in three of the seven infants. Demethylcitalopram (2.2 and 2.2 microg l(-1) was detected in plasma from two of the same infants. No adverse effects were seen in the infants, all were within appropriate percentile limits for weight and all had normal Denver developmental quotients. CONCLUSIONS: The mean combined dose of citalopram and demethylcitalopram (4.4-5.1% as citalopram equivalents) transmitted to infants via breast milk is below the 10% notional level of concern. Plasma concentrations of these drugs in the infants were very low or absent and there were no adverse effects. These data support the safety of the use of citalopram in breast feeding women. Nevertheless, each decision to breast feed should always be made as an individual risk:benefit analysis.

Adult↗

Increased endometrial thickness in women with hypertension.

OBJECTIVE: We noticed an increase in endometrial thickness in women with hypertension who were treated with a combination of medications, including beta-blockers. The purpose of this study was to examine whether the endometrium of hypertensive women is thicker than that of healthy women and to determine whether endometrial thickening in hypertensive women is directly related to the antihypertensive beta-blocker treatment. STUDY DESIGN: We compared 3 groups of postmenopausal patients as follows: (1) women with a history of essential hypertension treated with a combination of medications, including beta-blockers; (2) women with a history of hypertension treated with a combination of medications that did not include beta-blockers; and (3) healthy women without hypertension. All patients were interviewed and examined, blood tests were performed, and endometrial thickness in the anterior-posterior diameter was measured by vaginal ultrasonography. Among the exclusion criteria were diabetes or an abnormal fasting blood glucose level, obesity, hormonal medication or replacement hormonal therapy during the previous 6 months, and a history of hormonal disturbances, infertility, or polycystic ovary syndrome. RESULTS: Of 45 hypertensive women enrolled in the study, 22 were treated with a beta-blocker combination medication and 23 were treated with other antihypertensive medications. They were compared with 25 healthy women. There was no statistically significant difference in endometrial thickness between women treated with medications, including beta-blockers, and those who were treated with other hypotensive agents. Twenty percent of women with hypertension and none of the healthy women had endometrium >5 mm thick (P <.017; odds ratio, 8.22; 95% confidence interval, 1.22-infinity). CONCLUSION: Twenty percent of hypertensive postmenopausal women were found to have increased endometrial thickness. However, we were unable to substantiate an association between the type of treatment administered, whether beta-blockers were included, and the increase in endometrial thickness.

Adrenergic beta-Antagonists↗

Experimental use of raffinose as an osmotic agent for peritoneal dialysis.

Conventional glucose-based solutions for peritoneal dialysis fluids have been shown to raise problems of biocompatibility. We therefore evaluated the ultrafiltration capabilities of raffinose as an alternative osmotic agent in a non-uremic rat model. Animals were divided into four groups and injected intraperitoneally with solutions containing raffinose (4.5%, 345 mOsm/kg; 16.7%, 518 mOsm/kg) or glucose (1.5%, 346 mOsm/kg; 4.25%, 489 mOsm/kg). Data obtained from animals exposed to 16.7% raffinose were excluded because of precipitation of the osmotic agent. Low-osmolality raffinose solution induced higher ultrafiltered volume than the low-osmolality glucose-enriched fluid at 120 minutes of dwelling time. No significant differences were observed in effluent sodium and potassium concentration and protein dialysate-to-plasma (D/P) ratio. The D/P ratio of phosphate was higher in the low-osmolality raffinose-based fluid than in the low-osmolality glucose solution. The osmolality of the solutions was significantly decreased after a dwelling time of 120 minutes. We conclude that 4.5% raffinose is an effective osmotic agent. Total or partial replacement of glucose by raffinose for clinical peritoneal dialysis could be eventually considered after appropriate evaluation of its biocompatibility and general side effects.

Animals↗

Preterm lung function after retreatment with antenatal betamethasone in preterm lambs.

OBJECTIVE: We hypothesized that two doses of betamethasone administered 1 week apart would further enhance postnatal pulmonary function in preterm lambs (compared with a single dose). STUDY DESIGN: Fetal sheep (121 days' gestation) randomly received saline solution or betamethasone (0.5 mg/kg) as a single injection. Six days later fetal sheep were retreated with either saline solution or corticosteroid, and postnatal lung function was evaluated 1 day later. RESULTS: Betamethasone improved compliance and ventilation efficiency index nearly 50%, and total lung volume increased twofold. No effects of treatment-to-delivery interval (1 vs 7 days) or corticosteroid retreatment on pulmonary function were apparent. Although surfactant pool sizes increased as a function of duration of exposure, no additional effect of corticosteroid retreatment was noted. Antenatal betamethasone increased messenger ribonucleic acid levels for the surfactant proteins A and C, and retreatment augmented surfactant protein B messenger ribonucleic acid levels but suppressed surfactant protein A and C messenger ribonucleic acid. CONCLUSION: Improved postnatal lung function resulting from antenatal betamethasone was not augmented by retreatment.

Animals↗

Effects of severe hemorrhage on plasma ANP and glomerular ANP receptors.

Atrial natriuretic peptide (ANP) plays an important role in blood volume and electrolyte homeostasis in normovolemia and in hypervolemic states. The currently available information on the effects of hypovolemia on plasma ANP is contradictory. Moreover, possible regulation of ANP receptors during severe hemorrhagic hypovolemia has not been investigated. This study evaluated the effects of severe hemorrhage on plasma ANP and on the regulation of glomerular ANP receptor subtypes in anesthetized rats. Constant rate bleeding of 50% of total blood volume within 2 h induced a reproducible shock state characterized by marked decreases in blood pressure, heart rate, and hematocrit and an increase in plasma renin activity and aldosterone. Hemorrhaged rats exhibited a gradual significant increase in plasma ANP from 39.3 +/- 2.9 to 114.7 +/- 20.0 pmol/l 1 h after the bleeding (P < 0.001 from the initial value and P < 0.02 from the final value of sham-shock rats). Hemorrhage induced a significant decrease in total glomerular ANP binding sites (172 +/- 25 vs. 363 +/- 39 fmol/mg protein in hemorrhaged and sham-shock rats, respectively, P < 0.05). This decrease was mainly due to a significant decrease in ANPC receptors (132 +/- 22 vs. 312 +/- 40 fmol/mg protein in hemorrhaged and sham-shock rats, respectively, P < 0.05). Hemorrhage did not change glomerular ANPA receptor density. No significant differences in the affinity of the glomerular receptor subtypes for ANP were detected. Our data indicate that plasma ANP increases after prolonged severe hemorrhage. It is suggested that downregulation of renal ANPC receptors leads to reduced clearance of ANP and contributes to elevation of its plasma level after severe hemorrhage.

Animals↗

Postnatal lung function after prenatal steroid treatment in sheep: effect of gender.

The effect of fetal gender on postnatal lung function and response to prenatal steroid exposure were examined retrospectively in a group of 115 preterm lambs. Fetuses received a single intramuscular injection of 0.5 mg/kg betamethasone alone or in conjunction with L-thyroxine 48 h before delivery at 128-d gestational age. Control animals received an equivalent volume of saline. After delivery, respiratory mechanics and blood gas parameters were recorded for 40 min. Deflation pressure volume curves were constructed in excised lungs. Right upper lobes from a randomly selected subgroup of control animals were examined morphometrically. Control (saline-treated) females were able to be ventilated at lower ventilatory pressures with equivalent tidal volumes and more efficient gas exchange. There were no gender differences in compliance, conductance, or excised lung volumes for saline-treated animals. More efficient gas exchange in females could not be explained by thinner alveolar septa or greater alveolar surface area. After hormone treatment, both males and females exhibited significant improvements in respiratory mechanics, gas exchange, and an increase in alveolar surfactant concentration. However, female exhibited a significantly greater improvement than males for compliance, conductance, excised lung volume, and arterial oxygen partial pressure. These data provide a comprehensive description of gender differences in postnatal lung function and response to steroid treatment in preterm animals, and support clinical findings of sexual dimorphism.

Animals↗

Differing patterns of mechanical response to direct fetal hormone treatment.

A single combined intramuscular dose of betamethasone and l-thyroxine (T4) or placebo was injected into the shoulder of fetal lambs 48 hours prior to delivery at days 121 (n = 14), 128 (n = 25) or 135 (n = 20) of gestation. Respiratory mechanics were calculated using multiple linear regression analysis. Both respiratory system resistance (RRS) and elastance (ERS) decreased approximately 4 fold between gestational days 121 (D121) and 135 (D135). Both variables were also reduced by hormone treatment. Reduction in ERS was due to a reduction in both lung (EL) and chest wall (EW) components. In absolute terms EW decreased with gestational age; however, EW as a proportion of total elastance (% EW) increased. Inclusion of a volume-dependent elastance term in the multiple linear regression model enabled us to separate total elastance into volume-independent (E1) and volume-dependent (E2V) components. E1 decreased almost 8-fold compared with only a 2.5-fold fall in E2V between D121 and D135. %E2, the proportion of ERS which is volume-dependent and which provides an index of overventilation, doubled over this time period. Hormone treatment affected E1 and E2V components equally hence %E2 was not altered. Both excised lung volume and end expiratory alveolar volume increased with gestational age and with treatment. The response to treatment was qualitatively similar at each of the gestational ages examined, however, for all mechanics variables, except resistance and E1, the magnitude of response to treatment was significantly smaller in D135 animals compared with other age groups.

Airway Resistance↗

Late-onset infections of infants in neonatal units.

OBJECTIVE: To examine regional variations in the incidence of late-onset neonatal infections in Australian and New Zealand neonatal units. METHODOLOGY: A longitudinal, prospective surveillance study of systemic sepsis (septicaemia or meningitis) in 11 neonatal units: 10 in the Australian States of the Northern Territory, New South Wales, Queensland, Victoria and Western Australia, and 1 in Christchurch, New Zealand. The results are reported of late-onset neonatal infection (defined as sepsis after 48 h) for the second year of prospective surveillance, data being collected from 1 October 1992 to 30 September 1993. RESULTS: Data were available on 24535 live births in Australia, representing approximately 10% of all live births in the country. There were 320 episodes of sepsis in Australian units affecting 294 babies. One hundred of these episodes (31%) were early-onset; 3.0% of babies admitted to six tertiary care neonatal units attached to maternity hospitals developed late sepsis, and this rate did not differ between units. The proportion of babies infected was inversely related to birthweight: 22.6% of babies under 1OOOg, but 0.6% over 2000g. Coagulase negative staphylococci were the commonest cause of late-onset sepsis. There were 26 episodes of S. aureus septicaemia, of which only one was due to MRSA. Meningitis occurred in 13 babies (5.9%) with late-onset sepsis. The mortality from late-onset sepsis was 7.7%. CONCLUSIONS: Coagulase-negative staphylococci are the commonest cause of late-onset sepsis of babies in neonatal units. There were no major regional differences in the incidence of, or the organisms causing, late sepsis.

Australia↗

Effect of interval from fetal corticosteriod treatment to delivery on postnatal lung function of preterm lambs.

The effect of altering the interval from treatment to delivery on postnatal lung function of the preterm lamb is unknown. We treated groups of 8-10 singleton fetal sheep with 0.5 mg/kg betamethasone by fetal injection and evaluated postnatal lung function 40 min after preterm delivery at 123 days gestation 2 days after treatment or at 128 days gestation 2, 4, and 7 days after treatment relative to groups of 4-8 saline-injected control animals. At 123 days, betamethasone significantly improved arterial PCO2, dynamic thoracic compliance, and ventilatory efficiency index and doubled lung gas volume relative to a control group. Fetal treatment with betamethasone 2, 4, or 7 days before delivery at 128 days also improved these same indicators of lung function relative to controls, and the magnitude of the improvements was the same for all indicators and independent of treatment-to-delivery interval. Betamethasone suppressed the normal postnatal increase in plasma cortisol after 2 and 4 days of exposure but not after 7 days of exposure. Betamethasone also increased fetal and postnatal triiodothyronine concentrations after 2 days of exposure but not at 4 or 7 days of exposure. Although the hormone effects were transient, postnatal lung functional responses to betamethasone persisted over the 2- to 7-day interval from treatment to delivery.

Adrenal Cortex Hormones↗

Morphine increases synchronous ventilation in preterm infants.

OBJECTIVE: To examine the short-term cardiorespiratory effects of intravenous morphine infusion in ventilated preterm infants. METHODOLOGY: A randomized double-blind placebo-controlled trial in a neonatal intensive care unit. Twenty-six preterm infants (29-36 weeks gestation) with hyaline membrane disease requiring ventilatory assistance on the first day after birth were included in the study. A loading dose of morphine 100 micrograms/kg over 30 min followed by a continuous intravenous infusion at 10 micrograms/kg per hour was given. Primary measures were heart rate, blood pressure, respiratory rate and interaction of spontaneous respiration with mechanical ventilation. Secondary measures were durations of oxygen therapy, ventilator therapy and hospitalization as well as incidence of bronchopulmonary dysplasia, periventricular haemorrhage and pneumothorax. RESULTS: Morphine-treated infants spent a significantly greater percentage of total ventilated time breathing in synchrony with their ventilators (median [IQ] = 72[58-87] vs 31[17-51]%; P = 0.0008). Heart rate and respiratory rate, but not blood pressure, were reduced in morphine-treated infants. Duration of oxygen therapy was reduced (median [IQ] = 4.5[3-7] vs 8[4.75-12.5] days; P = 0.046). CONCLUSIONS: Intravenous morphine infusion increases synchronicity of spontaneous and ventilator-delivered breaths in preterm infants. Morphine reduces heart rate and respiratory rate without reducing blood pressure, and may help to reduce duration of oxygen therapy in preterm infants with hyaline membrane disease.

Double-Blind Method↗

C-reactive protein as a diagnostic tool of sepsis in very immature babies.

Three hundred and nine septic screens were performed on 123 consecutively admitted infants of < 30 weeks gestation. As part of the septic screen, serial quantitative measurements of C-reactive protein (CRP) were performed daily until discontinuation of antibiotic therapy. Complete blood counts were performed daily for the first 2 days of each septic episode. The babies had a mean birth weight of 1035.8 g s.d. 273.2 and a mean gestational age of 27 weeks s.d. 1.8. A CRP level of 10 mg/L or above was considered abnormal. Subsequently the receiver operator characteristic curve for CRP was constructed to demonstrate the ideal cut off value. Of the 309 septic screens, there were 51 instances of proven sepsis and 39 instances of deep culture negative sepsis. In the remaining 219, a diagnosis of proven or deep culture negative sepsis could not be made. On the first day of the septic episode CRP showed a sensitivity of 62.7%, specificity of 87.2% and negative predictive value of 92.2% for proven sepsis. There was a significant increase in the sensitivity (90.2%) and negative predictive value (97.7%) of CRP with a specificity of 80.6 when both day 1 and 2 estimations were combined. We conclude that when the CRP is elevated on day 1 and/or day 2, the diagnosis of sepsis is extremely likely and when the CRP is within normal limits on days 1 and 2 of the septic episode, neonatal sepsis can be confidently excluded and antibiotic therapy ceased.

C-Reactive Protein↗

Erythropoietin in very preterm infants.

Three neonates (a male and two females of gestational ages 27, 27 and 29 weeks with birthweight 985, 660 and 1130 g), born to parents who are Jehovah's Witnesses, were admitted to our neonatal intensive care unit over a 2 month period in 1992. Human recombinant erythropoietin (rHuEpo, 200 u/kg sc. on alternate days for 6-8 weeks) was started early in conjunction with strict control of blood sampling in an attempt to avoid the need for blood transfusion. The lowest haemoglobin recorded was 95 g/L at 35 days of age in the first infant. The amount of blood withdrawn for sampling was 21.4 mL, 20.7 mL and 5.5 mL, respectively. All were discharged near their expected birthdate, never having received a blood transfusion in the Nursery. It is possible to manage sick, very preterm, very low birthweight neonates in a neonatal intensive care setting without the use of blood transfusions by the early use of rHuEpo in conjunction with strict control of blood sampling.

Anemia, Neonatal↗

Time course of changes in lung mechanics following fetal steroid treatment.

We studied the effect of a single-dose, corticosteroid treatment on preterm lambs (gestational age: 128 d). A low, medium, or high betamethasone dose (0.1, 0.5, and 2.0 mg/kg) or saline control was administered directly to the fetus by ultrasound-guided intramuscular injection 48 h before delivery. A second group received either the high dose of betamethasome or saline 24 h before delivery. The lambs were delivered at 128 d gestation, anesthetized with ketamine, and ventilated for 50 min. Respiratory system elastance and resistance were measured at 10-min intervals using multiple linear regression analysis of pressure, flow, and volume. Similarly, estimates of lung mechanics were calculated from transpulmonary pressure. The viscoelastic time constant (tau) was calculated by fitting an exponential to the pressure changes occurring after occluding the airway during expiration. Excised lung volume at 40 cm H2O and lung weight were used to calculate specific elastance and resistance correcting for lung size using volume or weight, respectively. Of the 13 lambs in the 48-h high-dose betamethasone group, five developed pulmonary interstitial emphysema (PIE) as did 3 of 11 animals in the high-dose group treated 24 h before delivery. These animals were analyzed separately. The lambs receiving medium- or high-dose (24 and 48 h predelivery) betamethasone had significantly lower elastance and a trend toward lower resistance when compared with the control groups. Ten minutes after delivery, the animals that developed PIE all had elastance values comparable to that of the control animals despite corticosteroid treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

Ureaplasma urealyticum in a neonatal intensive care population.

The incidence of Ureaplasma colonization at birth and its effect on the development of chronic lung disease (CLD) and on mortality was studied in a neonatal intensive care population. Ureaplasma colonization was associated with a birthweight < 1000 g (odds ratio [OR] 3.45 confidence intervals [CI] 2.13-5.60) and a gestational age < 30 weeks (OR 2.54 CI 1.71-3.79). In a case-controlled study of 112 infants, significant associations with Ureaplasma colonization were maternal pyrexia in labour (n = 38 vs 21; P = 0.015), the requirement for antibiotics in labour (n = 39 vs 16; P = 0.0005) and vaginal delivery (n = 78 vs 58; P = 0.009). Risk factors associated with the development of CLD were birthweight < 1000 g (OR 3.77 CI 2.53-5.62) and delivery by Caesarean section (OR 1.65 CI 1.11-2.43). Within the group delivered by Caesarean section. Ureaplasma colonization was also associated with an increased risk of CLD (OR 1.97 CI 1.08-3.62). Ureaplasma colonization of infants at birth is associated with factors suggestive of maternal chorioamnionitis as well as preterm birth and low birthweight. In infants delivered by Caesarean section, Ureaplasma colonization is associated with an increased risk of chronic lung disease.

Adult↗

An update of the results of intensive therapy in children with acute lymphoblastic leukemia.

On January 1984 a protocol for newly diagnosed children with acute lymphoblastic leukemia started in a multiinstitutional setting in Argentina, Costa Rica and Cuba. The protocol was based on the BFM 76/79 study. It consisted in 8 drug 8 weeks induction-consolidation regimen with a delayed intensification regimen followed by maintenance with 6-mercaptopurine-methotrexate and pulses with vincristine-prednisone for 36 months. CNS prophylaxis with IT therapy, age based schedule was given. Only patients with greater than 50000 WBC counts received cranial irradiation. A total of 720 patients were registered up to June 1987, 703 of them were eligible. Six hundred an twenty six (89%) of the patients achieved complete remission, 7 partial remission, 8 failed to respond and 62 (9%) had drug or disease related death before completing induction therapy. At 72 months 50% remained in complete remission, 45% and 58% of all the patients remained disease-free and alive respectively. Sites of relapse were bone marrow 21%, CNS 10%, testis 2%, combined 4% and 8% died in complete remission. No difference in response was observed among the three prognostic groups, however the disease-free survival at 72 months was 52% for good prognosis compared to 42% for intermediate and poor prognosis (P = 0.0009). This results showed a marked improvement over previous studies of our group and, that, intensive and large clinical trials can be performed in Latinamerica.

Adolescent↗