Role of probiotics in pediatric patients with Helicobacter pylori infection: a comprehensive review of the literature

BACKGROUND

The current guidelines suggest the use of triple therapy as first choice treatment of Helicobacter pylori infection, although the eradication failure rate is more than 30%. Current interest in probiotics as therapeutic agents against H. pylori is stimulated not only by the clinical data showing efficacy of some probiotics in different gastrointestinal diseases but also by the increasing resistance of pathogenic bacteria to antibiotics, thus the interest for alternative therapies is a real actual topic.

AIM

To review in vitro and in vivo studies on the role of probiotics in H. pylori infection focusing on the paediatric literature.

MATERIALS AND METHODS

Pre-clinical and clinical paediatric studies in English assessing the role of probiotics in H. pylori infection identified by MEDLINE search (1950-2009) were reviewed.

RESULTS

In vitro studies demonstrated an inhibitory activity of probiotics on H. pylori growth and that this effect is extremely strain specific. Available data in children indicate that probiotics seems to be efficacious for the prevention of antibiotic associated side-effects, and might be of help for the prevention of H. pylori complications by decreasing H. pylori density and gastritis, and for the prevention of H. pylori colonization or re-infection by inhibiting adhesion to gastric epithelial cells. There is no clear evidence that probiotics may increase the H. pylori eradication rate.

CONCLUSION

Both in vitro and in vivo studies provide evidence that probiotics may represent a novel approach to the management of H. pylori infection.

Anti-pituitary antibodies in children with newly diagnosed celiac disease: a novel finding contributing to linear-growth impairment

OBJECTIVES

The possible autoimmune involvement of the pituitary gland in patients with celiac disease (CD) has been suggested but demonstrated in only a few patients on gluten-free diet. We aimed to assess the prevalence and clinical meaning of anti-pituitary antibodies (APA) in children and adolescents with the newly diagnosed CD.

METHODS

A total of 119 patients with CD (0.9-15.8 years old) attending the inpatient clinic of University Hospital were recruited for the cross-sectional study. Their height, weight, and body mass index (BMI) were recorded, and insulin-like growth factor-1 (IGF-1) and APA were assayed. APA was also determined in 98 sex- and age-matched controls.

RESULTS

APA were detected in 50 patients (42.0%), 15 of them with high titer (30%) and 35 with low titer (70%), and in 2 control subjects at low titer (2%) (P<0.001). IGF-1 was higher in patients with negative than with low titer (P=0.02) or high titer APA (P=0.03). Height was more reduced in high-titer APA patients than in the negative ones (P<0.01). Height was positively correlated with IGF-1 (P<0.01) and negatively with chronological age (P=0.001). IGF-1 was positively correlated with BMI (P<0.001). For height prediction the regression analysis showed the rank order 1 for chronological age and 2 for IGF-1.

CONCLUSIONS

In this paper we have shown a remarkable prevalence of positive APA in newly diagnosed CD patients. High APA titers are associated with height impairment, likely mediated by a reduction of IGF-1, thus suggesting that autoimmune pituitary process could induce a linear-growth impairment.

Thyroid function and thyroid autoimmunity in childhood acute lymphoblastic leukemia off-therapy patients treated only with chemotherapy

OBJECTIVE

Scanty data are available about the thyroid function in childhood acute lymphoblastic leukemia (ALL) off-therapy patients treated only with chemotherapy. We aimed to assess the prevalence of thyroid autoimmunity and thyroid dysfunction in such patients.

DESIGN

Case-control cross-sectional study.

METHODS

Eighty-four patients diagnosed with ALL and treated only with chemotherapy. Mean age at diagnosis 5.9+/-3.6 yr, at recruitment 12.1+/-4.3 yr. The treatment had been stopped 4.3+/-3.2 yr before recruitment. A control group of 60 subjects was recruited. Free T4, TSH, anti-thyroperoxidase, and anti-thyroglobulin antibodies were measured.

RESULTS

Anti-thyroglobulin and anti-thyroperoxidase antibodies were negative in all patients. TSH was increased in 7 patients (8.3%) and 3 controls (5.0%). Free T4 was within the normal limits in all patients and controls.Mean TSH and free T4 levels did not statistically differ between controls and ALL offtherapy patients. TSH was negatively correlated with the age at the diagnosis (p=0.01) and the age at the end of therapy (p=0.008). Anti-thyroglobulin and/or anti-thyroperoxidase antibodies were detected in 3 controls (5%; vs study group: p=0.038), 1 of them with increased TSH.

CONCLUSIONS

Some patients present hyperthyrotropinemia, without anti-thyroid antibodies, with a prevalence comparable to the control group. The thyroid gland seems more prone to be damaged by chemotherapy at a younger age. We think that a thyroid follow- up in ALL off-therapy patients may be advisable and should be differentiated on the basis of the age at the end of treatment, with more frequent tests for younger patients.

Growth and endocrine function in thalassemia major in childhood and adolescence

BACKGROUND

Thalassemia major is an inherited hemoglobin disorder characterized by chronic anemia and iron overload due to transfusion therapy and gastrointestinal absorption. Iron overload causes most of the associated mortality and morbidity and frequently involves the endocrine glands.

AIM

To review the most pertinent literature on the topic.

METHODS

One hundred and twenty-three papers were evaluated.

RESULTS

Disproportionate short stature is frequent and becomes more evident at puberty because of the lack of growth spurt. Later on, partial height recovery may occur. Long-term treatment with recombinant human GH seems ineffective to improve final height. Pubertal development is characterized by a clinical spectrum ranging from hypogonadism to a simple delay in starting and developing of puberty. Hormonal replacement is mandatory in cases of absent or arrested puberty. Pancreatic beta-cells function may be impaired during adolescence or later on. Its impairment ranges from hyperinsulinemia, secondary to insulin resistance, with normal glucose tolerance to beta-cells failure with insulin-dependent diabetes mellitus. Primary hypothyroidism may affect thalassemic patients from the second decade of life. The thyroid dysfunction may be reversible (if an intensive chelation therapy regimen is started in the precocious phase), stationary, or slowly progressive. Central hypothyroidism is less common and autoimmune thyroiditis absent.

CONCLUSION

Despite the improvement of the treatment, the involvement of the endocrine system still burdens the life of these patients. Further therapeutic improvement would reasonably reduce morbidity and, hopefully, mortality of thalassemic patients and make the endocrine disorders easier to treat.

Regurgitation in healthy and non healthy infants

Uncomplicate regurgitation in otherwise healthy infants is not a disease. It consists of milk flow from mouth during or after feeding. Common causes include overfeeding, air swallowed during feeding, crying or coughing; physical exam is normal and weight gain is adequate. History and physical exam are diagnostic, and conservative therapy is recommended. Pathologic gastroesophageal reflux or gastroesophageal reflux disease refers to infants with regurgitation and vomiting associated with poor weight gain, respiratory symptoms, esophagitis. Reflux episodes occur most often during transient relaxations of the lower esophageal sphincter unaccompanied by swallowing, which permit gastric content to flow into the esophagus. A minor proportion of reflux episodes occurs when the lower esophageal sphincter fails to increase pressure during a sudden increase in intraabdominal pressure or when lower esophageal sphincter resting pressure is chronically reduced. Alterations in several protective mechanisms allow physiologic reflux to become gastroesophageal reflux disease; diagnostic approach is both clinical and instrumental: radiological series are useful to exclude anatomic abnormalities; pH-testing evaluates the quantity, frequency and duration of the acid reflux episodes; endoscopy and biopsy are performed in the case of esophagitis. Therapy with H2 receptor antagonists and proton pump inhibitors are suggested.

Effects of probiotic and prebiotic on gastrointestinal motility in newborns

To fortify the biological role of milk formula has been suggested to use probiotics and prebiotics as functional components to mimic the effect of breast milk. The aim of this study was to evaluate the effects of prebiotic, probiotic added to a standard formula on gastrointestinal motility respect to placebo-formula. Cutaneous electrogastrography (EGG) and ultrasound gastric emptying (GE) were performed in 49 preterm newborns. 17 newborns were exclusively breast-fed; 32 were randomly assigned to receive prebiotic-added formula (0.8 g/dl of a mixture from scGOS and lcFOS, ratio 9:1) (10), a probiotic-added formula (L. reuteri at dose of 1x10(8) colony forming units (CFU) per day) (10), a formula with placebo (12) for 30 days. No difference was seen in the nutritional parameters and no adverse events were reported. After the intervention period, the prebiotic, probiotic, and breast milk groups showed a higher percentage of EGG slow wave propagation and faster gastric half emptying time respect to placebo group (ANOVAon ranks p<0.001; Dunn test vs control: prebiotic, probiotic and breast-milk vs placebo formula p<0.05; and ANOVA on ranks p=0.005; Dunn test vs control: prebiotic, probiotic and breast-milk vs placebo formula p<0.05, respectively). Feeding preterm infants with a formula supplemented with prebiotics or probiotics may stimulate gastric emptying and improve maturation of the EGG activity mimicking the effect of breast milk.

PTPN11 gene mutation and severe neonatal hypertrophic cardiomyopathy: what is the link?

Noonan syndrome (NS) is an autosomal dominant disorder characterized by multiple dysmorphic features and a broad spectrum of congenital heart defects. Specific mutations of the PTPN11 gene are associated with 50% of the NS cases and 90% of the multiple lentigines/LEOPARD syndrome (ML/LS) cases. These two allelic conditions have several overlapping clinical features. This study describes the association between the Gln510Glu mutation of the PTPN11 gene and lethal progressive hypertrophic cardiomyopathy (HCM) in a newborn with the NS phenotype. The findings confirm the intriguing relationship between site-specific mutations of the PTPN11 gene and rapidly progressive HCM.

17beta-Hydroxysteroid dehydrogenase-3 deficiency: from pregnancy to adolescence

OBJECTIVE

Aim of this study is to report on basal clinical phenotype and follow up after diagnosis, of patients with 17beta-hydroxysteroid-dehydrogenase type 3 (17beta-HSD3) deficiency in Italy.

SETTING

Pediatric Endocrine Departments, University Hospitals.

PATIENTS

The cases of 5 Italian subjects affected by 17beta-HSD3 deficiency are presented in this study.

INTERVENTIONS

Laboratory and genetic assessment. Gonadectomy and female sex assignment (4 patients) or GnRH analog therapy to regress puberty and gender identity disorder (1 patient).

RESULTS

Presentation lasted from pregnancy (pre-natal diagnosis of a 46,XY fetus with female external genitalia) to infancy (inguinal hernia containing testes/clitoromegaly) and adolescence (virilisation). All subjects but one (subject 1, Central-Northern Italy) were from small areas of Southern Italy. Endocrine data (baseline and/or stimulated testosterone/ Delta4-androstenedione ratio) were informative. Two girls were homozygous for 17beta-HSD3 gene mutations (G289S/G289S; R80W/R80W), while the others were compound heterozygous (IVS325+4 A>T/A203V; L212Q/M235V; R80W/A235E). Four patients were confirmed as females and were well-adjusted with assigned sex; gender identity disorder improved during treatment with GnRH analog in the last subject.

CONCLUSIONS

17betaHSD3 deficiency may present from pregnancy to puberty for different clinical issues. Albeit testosterone/Delta4-androstenedione ratio represents the most accurate endocrine marker to diagnose the disorder, hCGstimulation is mandatory in pre-puberty. Molecular analysis of 17beta-HSD3 gene should be performed to confirm the diagnosis. Temporary GnRH analog treatment may regress gender identity disorder and provide time to confirm or change the birth sex assignment. Female individuals seems to be compliant with their sex, providing that virilisation does not occur. In Italy, the disorder seems to be more prevalent in the Southern regions and shows genetic heterogeneity.

Growth hormone deficiency and antipituitary antibodies in a patient with common variable immunodeficiency

Common variable immunodeficiency (CVID) is characterized by hypogammaglobulinemia and T-lymphocytes dysfunction. Autoimmune diseases are frequent. A 10.7-yr-old female, diagnosed with CVID when 7 yr old, was referred because of short stature. She was pre-pubertal and short (height -2.86 SD score) with delayed bone age. Her intestinal absorption, routine biochemistry, heart, renal, liver, and thyroid functions were normal. Two stimulation tests for GH showed a maximum peak of 1.9 ng/ml (IGF-1: 154 ng/ml, 147-832). When the patient was 13 yr old (height -4.23 SD score, telarche and pubarche stage 2, bone age 6.25 yr), GH treatment was initiated. Despite poor compliance, the growth velocity showed improvement. Anti-thyrogobulin, anti-thyroperoxidase, anti-21-hydroxylase, and anti-tyrosine-phosphate antibodies were negative while anti- pituitary antibodies (APA) were positive. For the first time, the presence of APA (previously associated with GH deficiency in non-CVID subjects) is reported in a CVID patient. The possibility of an autoimmune involvement of the pituitary gland was previously debated for CVID patients, but had never been demonstrated. This case suggests that in CVID, the pituitary gland can be targeted by autoantibodies and thus a more comprehensive follow-up of these patients should be performed.

Osteoclastogenesis in children with 21-hydroxylase deficiency on long-term glucocorticoid therapy: the role of receptor activator of nuclear factor-kappaB ligand/osteoprotegerin imbalance

CONTEXT

Children with 21-hydroxylase deficiency (21-OHD) need chronic glucocorticoid (cGC) therapy to replace congenital deficit of cortisol synthesis. cGC therapy is the most frequent and severe form of drug-induced osteoporosis, and different mechanisms have been proposed to explain its pathogenesis.

OBJECTIVE

We investigated the osteoclastogenic potential of peripheral blood mononuclear cells (PBMCs) from 18 children with 21-OHD on cGC therapy and 25 controls who never received GCs. We also evaluated the presence of circulating osteoclast precursors (OCPs) and the role of T cells in osteoclast formation.

RESULTS

Spontaneous osteoclastogenesis, without adding macrophage-colony stimulating factor and receptor activator of nuclear factor-kappaB ligand (RANKL), and significantly higher osteoclasts resorption activity occurred in 21-OHD patients. Conversely, macrophage-colony stimulating factor and RANKL were essential to trigger and sustain osteoclastogenesis in controls. Furthermore, in 21-OHD patients, we identified a significant percentage of CD11b-CD51/CD61 and CD51/61-RANK-positive cells, which are OCPs strongly committed. Additionally, we demonstrated a T cell-dependent osteoclastogenesis from 21-OHD patients' PBMCs. T cells from patients expressed high levels of RANKL and low levels of osteoprotegerin (OPG) with respect to controls. Moreover, 21-OHD patients had higher soluble RANKL and lower OPG serum levels compared with controls; thus, soluble RANKL to OPG ratio was significantly higher in patients than controls.

CONCLUSIONS

The present study showed for the first time a high osteoclastogenic potential of PBMCs from 21-OHD patients on cGC therapy. This spontaneous osteoclastogenesis seems to be supported by both the presence of circulating OCPs and factors released by T cells.

Acute pancreatitis in a girl with panhypopituitarism due to craniopharyngioma on growth hormone treatment. A combination of risk factors

Craniopharyngioma is a rare, benign, suprasellar brain tumor associated with a significant number of endocrine and metabolic impairments. Growth hormone deficiency, caused by the tumor itself or by its subsequent surgical treatment, is the most common hormone deficiency in these patients and replacement is frequently necessary. Hypothalamic obesity observed after surgery treatment, whether combined with radiotherapy or not, presents with increased abdominal fat and altered lipid profiles and is likely caused by both disruption of the mechanisms controlling satiety, hunger and energy balance and impairment of sensitivity to leptin, insulin and ghrelin axis. It is well known that hyperlipemia is associated with acute pancreatitis, both as a precipitant and as an epiphenomenon. Moreover, the increased incidence of acute pancreatitis during growth hormone therapy is possibly due to increased enzyme production (e.g., amylase, lipase and elastase). We report the case of a 13-year-old girl affected by craniopharyngioma on growth hormone replacement treatment who developed acute pancreatitis. We suggest including routine evaluation of lipid profile during follow-up of all children on growth hormone treatment, especially those affected by hypopituitarism secondary to craniopharyngioma, given pancreatic adverse effects of growth hormone replacement therapy and associated metabolic impairment due to hypothalamic obesity.

Sulfonylurea treatment in a girl with neonatal diabetes (KCNJ11 R201H) and celiac disease: impact of low compliance to the gluten free diet

A girl with celiac disease and KCNJ11 mutation was transferred to glibenclamide when 19.8 years old. When her compliance to the gluten free diet worsened, her metabolic control deteriorated. Since glibenclamide is absorbed in the intestine, its absorption seems to be impaired by chronic malabsorption, increasing the risk of hyperglycaemia.

Effects of moderate-severe exercise on blood glucose in Type 1 diabetic adolescents treated with insulin pump or glargine insulin

BACKGROUND

Few papers focus on exercise-related blood glucose (BG) in patients on continuous sc insulin infusion (CSII) or multiple daily injections (MDI) with glargine.

AIM

The main objective was to evaluate the degree of glycemic control in Type 1 diabetes mellitus adolescents on CSII doing physical activity with pump switched on or off. These findings were also compared with a small group of patients on MDI with glargine.

SUBJECTS AND METHODS

Eight patients on CSII (basal rate continued or turned off in alternating sessions) and 5 on MDI joined 4 sessions of moderate-severe exercise.

RESULTS

Post-exercise BG significantly increased with the pump off and was unchanged/decreased with the pump on and MDI groups vs baseline. The hypoglycemia rate was not different among the 3 groups at any time. Pump on: hypoglycemias more frequent both at bedtime (p=0.031) and at awakening (p<0.001) than before dinner and at awakening than at bed-time (p=0.044). Pump off: hypoglycemias more frequent both at bed-time (p=0.010) and at awakening (p=0.031) than before dinner. MDI: no differences.

CONCLUSIONS

Glargine is safe and reducing the pre-lunch insulin is unnecessary. Subjects on insulin pump should not stop the basal rate. If they stop the pump, some actions are advisable: pre-exercise insulin bolus, pre-sleeping snack rich in carbohydrates, slight reduction of the overnight basal rate. On the other hand, if the basal rate is unmodified, the ingestion of sugary drinks during the exercise, the reduction of the overnight basal rate, a reduction of the pre-dinner insulin bolus and/or a pre-sleeping snack should be considered.

Maturation of gastric electrical activity, gastric emptying and intestinal permeability in preterm newborns during the first month of life

INTRODUCTION

Immaturity of motility, intestinal epithelial barrier function and absorptive capacity may play a role in the pathophysiology of intestinal diseases in preterms. We determined the gastric electrical activity and emptying, and intestinal permeability, in preterm newborns to verify if a maturation pattern exists in preterm newborns during the first month of life.

PATIENTS AND METHODS

Eighteen preterm newborns (median 34 wks, range 2 wks) completed the study. They underwent the recording of gastric electrical activity by means of cutaneous electrogastrography, the ultrasound examination of gastric emptying, and the lactulose-to-mannitol ratio from permeability-absorption test on days 3, 7, 15, and 30 after birth.

RESULTS

Gastric electrical activity and emptying showed only slight changes between day 3 and day 7. On the contrary, an evident maturation in permeability, expressed as L/Mratio, was evident over time (Friedman Repeated Measures Analysis, p = 0.004).

CONCLUSION

In preterm healthy newborns of 34 weeks gestational age, electrical and motor activity are completely developed at birth whilst the intestinal epithelial barrier clearly improves during the first week of life.

The effects of probiotics on feeding tolerance, bowel habits, and gastrointestinal motility in preterm newborns

OBJECTIVE

To investigate the effect of dietary supplementation with a probiotic on feeding tolerance and gastrointestinal motility in healthy formula-fed preterm infants.

STUDY DESIGN

Thirty preterm newborns were enrolled; 10 were exclusively breast-fed, and the remaining 20 were randomly assigned in a double-blind manner to receive either Lactobacillus reuteri ATCC 55730 (at dose of 1 x 10(8) colony forming units a day) or placebo for 30 days. Clinical symptoms of gastrointestinal function (regurgitation, vomiting, inconsolable crying, and evacuation) and physiological variables (gastric electrical activity and emptying) were recorded before and after the dietary intervention.

RESULTS

Body weight gains per day were similar for the 3 groups, and no adverse events were recorded. Newborns receiving probiotics showed a significant decrease in regurgitation and mean daily crying time and a larger number of stools compared with those given placebo. Gastric emptying rate was significantly increased, and fasting antral area was significantly reduced in both the newborns receiving L. reuteri and breast-fed newborns compared with placebo.

CONCLUSIONS

Our results suggest a useful role for L. reuteri supplementation in improving feeding tolerance and gut function in formula-fed preterm newborns.

SOX2 plays a critical role in the pituitary, forebrain, and eye during human embryonic development

CONTEXT

Heterozygous, de novo mutations in the transcription factor SOX2 are associated with bilateral anophthalmia or severe microphthalmia and hypopituitarism. Variable additional abnormalities include defects of the corpus callosum and hippocampus.

OBJECTIVE

We have ascertained a further three patients with severe eye defects and pituitary abnormalities who were screened for mutations in SOX2. To provide further evidence of a direct role for SOX2 in hypothalamo-pituitary development, we have studied the expression of the gene in human embryonic tissues.

RESULTS

All three patients harbored heterozygous SOX2 mutations: a deletion encompassing the entire gene, an intragenic deletion (c.70_89del), and a novel nonsense mutation (p.Q61X) within the DNA binding domain that results in impaired transactivation. We also show that human SOX2 can inhibit beta-catenin-driven reporter gene expression in vitro, whereas mutant SOX2 proteins are unable to repress efficiently this activity. Furthermore, we show that SOX2 is expressed throughout the human brain, including the developing hypothalamus, as well as Rathke's pouch, the developing anterior pituitary, and the eye.

CONCLUSIONS

Patients with SOX2 mutations often manifest the unusual phenotype of hypogonadotropic hypogonadism, with sparing of other pituitary hormones despite anterior pituitary hypoplasia. SOX2 expression patterns in human embryonic development support a direct involvement of the protein during development of tissues affected in these individuals. Given the critical role of Wnt-signaling in the development of most of these tissues, our data suggest that a failure to repress the Wnt-beta-catenin pathway could be one of the underlying pathogenic mechanisms associated with loss-of-function mutations in SOX2.

Inhibition of Helicobacter pylori infection in humans by Lactobacillus reuteri ATCC 55730 and effect on eradication therapy: a pilot study

BACKGROUND

Several studies report an inhibitory effect of probiotics on Helicobacter pylori.

AIM

To test whether Lactobacillus reuteri ATCC 55730 reduces H. pylori intragastric load in vivo, decreases dyspeptic symptoms, and affects eradication rates after conventional treatment.

MATERIALS AND METHODS

In a double-blind placebo-controlled study, 40 H. pylori-positive subjects were given L. reuteri once a day for 4 weeks or placebo. All underwent upper endoscopy, (13)C-urea breath test, and H. pylori stool antigen determination at entry and (13)C-urea breath test and H. pylori stool antigen (used as both qualitative and semiquantitative markers) after 4 weeks of treatment. Sequential treatment was administered subsequently to all.

RESULTS

In vivo, L. reuteri reduces H. pylori load as semiquantitatively assessed by both (13)C-urea breath test delta-value and H. pylori stool antigen quantification after 4 weeks of treatment (p < .05). No change was shown in patients receiving placebo. L. reuteri administration was followed by a significant decrease in the Gastrointestinal Symptom Rating Scale as compared to pretreatment value (p < .05) that was not present in those receiving placebo (p = not significant). No difference in eradication rates was observed.

CONCLUSIONS

L. reuteri effectively suppresses H. pylori infection in humans and decreases the occurrence of dyspeptic symptoms. Nevertheless, it does not seem to affect antibiotic therapy outcome.

Clinical, endocrine, and molecular findings in 17beta-hydroxysteroid dehydrogenase type 3 deficiency

The 17beta-hydroxysteroid dehydrogenases (17betaHSD) gene family comprises different enzymes involved in the biosynthesis of active steroid hormones. The 17betaHSD type 3 (17betaHSD3) isoenzyme catalyzes the reductive conversion of the inactive C19-steroid, Delta4-androstenedione (Delta4- A), into the biologically active androgen, testosterone (T), in the Leydig cells of the testis. It is encoded by the 17beta-hydroxysteroid dehydrogenase type 3 (HSD17B3) gene, which maps to chromosome 9q22. Mutations in the HSD17B3 gene are associated with a rare form of 46,XY disorder of sex development referred to as 17betaHSD3 deficiency (or as 17-ketosteroid reductase deficiency), due to impaired testicular conversion of Delta4-A into T. 46,XY patients with 17betaHSD3 deficiency are usually classified as female at birth, raised as such, but develop secondary male features at puberty. Diagnosis, and consequently early treatment, is difficult because clinical signs from birth until puberty may be mild or absent. Biochemical diagnosis of 17betaHSD3 deficiency requires measurement of serum T/Delta4-A ratio after hCG stimulation test in pre-pubertal subjects, while baseline values seem to be informative in early infancy and adolescence. However, low basal T/Delta4-A ratio is not specific for 17betaHSD3 deficiency, being sometimes also found in patients with other defects in T synthesis or with Leydig cells hypoplasia. Mutational analysis of the 17HSDB3 gene is useful in confirming the clinical diagnosis of 17betaHSD3 deficiency. This review describes clinical findings, diagnosis, and molecular basis of this rare disease.

Longitudinal Assessment of Levo-Thyroxine Therapy for Congenital Hypothyroidism: Relationship with Aetiology, Bone Maturation and Biochemical Features

AIMS

To evaluate therapy and dose adjustments in patients with congenital hypothyroidism (CH), longitudinally followed up until 16 years old, according to aetiology, Beclard's nuclei presence, and thyroxine (T4) level at diagnosis.

METHODS

L-T4/kg/day and dose change ratio (CR) were assessed in 74 CH patients.

RESULTS

The dose was statistically larger in athyreosis than in dyshormonogenesis (1-10 and beyond 14 years) and in ectopy (2, 15, 16 years). The ectopic children required statistically larger L-T4/kg than the dyshormonogenetic ones (3-7 years). The L-T4/kg/day was increased, not statistically, in patients or with T4 <30 nmol/l or without Beclard's nuclei at diagnosis. The CR progressively dropped after the 6th month at each attendance, without any difference in terms of aetiology, T4 level at diagnosis, or Beclard's nuclei. The total CR was greater (significantly) in patients without Beclard's nuclei, and (not significantly) in those with T4 <30 nmol/l at diagnosis or with agenesia.

CONCLUSION

The L-T4 dose in CH is highly affected by the aetiology. The CR is higher in patients with delayed bone maturation at diagnosis. We suggest that these latter patients need blood tests more frequently to obtain a proper titration of the therapy.

Lactobacillus reuteri therapy to reduce side-effects during anti-Helicobacter pylori treatment in children: a randomized placebo controlled trial

BACKGROUND

Helicobacter pylori eradication fails in about 25-30% of children, particularly because of the occurrence of resistance to antibiotics and side-effects.

AIM

To determine whether adding the Lactobacillus reuteri to an anti-H. pylori regimen could help to prevent or minimize the gastrointestinal side-effects burden in children.

METHODS

Forty H. pylori-positive children (21 males; median age: 12.3 years) were consecutively treated with 10-day sequential therapy [omeprazole + amoxycillin for 5 days, and omeprazole + clarithromycin + tinidazole for other 5 days] and blindly randomized to receive either L. reuteri ATCC 55730 (10(8) CFU) or placebo. All children completed the Gastrointestinal Symptom Rating Scale (GSRS) at entry, during and after treatment. H. pylori status was assessed after 8 weeks by (13)C-urea breath test.

RESULTS

Overall, in all probiotic supplemented children when compared with those receiving placebo there was a significant reduction of GSRS score during eradication therapy (4.1 +/- 2 vs. 6.2 +/- 3; P < 0.01) and at the end of follow-up (3.2 +/- 2 vs. 5.8 +/- 3.4; P < 0.009). Overall, children receiving L. reuteri report less symptoms than those receiving placebo.

CONCLUSION

L. reuteri is capable of reducing frequency and intensity of antibiotic-associated side-effects during eradication therapy for H. pylori.

Divergent phenotype of two siblings human leukocyte antigen identical, affected by nonclassical and classical congenital adrenal hyperplasia caused by 21-hydroxylase deficiency

CONTEXT

Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders most often caused by enzyme 21-hydroxylase deficiency. Most mutations causing enzymatic deficiency are generated by recombinations between the active gene CYP21 and the pseudogene CYP21P. Only 1-2% of affected alleles result from spontaneous mutations. The phenotype of CAH varies greatly, usually classified as classical or nonclassical, depending on variable degree in 21-hydroxylase activity. Here we report a divergent phenotype of two human leukocyte antigen identical siblings, affected by nonclassical and classical CAH caused by 21-hydroxylase deficiency due to different genotype.

PATIENTS AND METHODS

Using direct sequencing method and Southern blot, we studied two children (one male and one female), affected, respectively, by nonclassical and classical CAH and their parents.

RESULTS

The mother was heterozygous for the Q318X mutation, and the father was heterozygous for the V281L mutation. The brother was a compound heterozygote for the mutations V281L and Q318X, whereas the proband was compound heterozygote for the Q318X mutation and a large conversion. The two children are human leukocyte antigen identical (A*02;B*14;DRB1*01/A*33;B*14;DRB1*03).

CONCLUSIONS

Different phenotype of the proband is the result of compound heterozygosity for the maternal mutation Q318X and a de novo large conversion.

Factors predicting final height in early treated congenital hypothyroid patients

OBJECTIVE

To evaluate pubertal development and final height (FH) in early treated patients with congenital hypothyroidism (CH) and to identify the main factors predicting FH.

DESIGN

Retrospective.

PATIENTS

Eighty-five patients with early diagnosed and treated CH.

MEASUREMENTS

Evaluation of length/height at diagnosis (mean age 26.6 days), at onset of puberty, and at the end of linear growth.

RESULTS

Mean FH was 161.7 cm in females and 173.8 cm in males, within +/- 0.9 cm of the 50th percentile of Italian growth charts, 5 cm higher than the mean target height (TH). Linear growth did not differ according to thyroid imaging findings. In males, height at onset of puberty was 0.16 standard deviation score (SDS), not statistically different from FH (-0.09 SDS). In females, height both at onset of puberty (0.39 SDS) and at menarche (0.57 SDS) was significantly higher (P < 0.001) than FH (-0.10 SDS). Puberty started at a mean chronological age of 10.2 and 11.6 years in females and males, respectively, with a corresponding bone age. FH correlated with TH and height at diagnosis, at onset of puberty, and at menarche. Multiple regression analysis showed that height at onset of puberty and TH are the most important factors explaining FH variability, although height at onset of puberty is slightly more important.

CONCLUSIONS

Our results, obtained in the largest reported available group of congenital hypothyroid patients, show that final height is higher than target height in both sexes and that height at onset of puberty is the main factor affecting final height.

[Treatment for Helicobacter pylori in children. Recent advances]

Helicobacter pylori (H. pylori) is a highly prevalent pathogen considered as an aetiological factor for gastric ulcers and gastric cancer. Most children colonized by H. pylori are asymptomatic and remain untreated. In symptomatic patients, the antibiotic treatment is not 100% effective because of the resistance to antibiotics and the imperfect patient compliance. Mono-therapy or dual-therapy have a very low efficacy. Dual therapies with bismuth plus one antibiotic or two antibiotics for two weeks are as effective as either bismuth-based or proton pump inhibitor-based triple therapies. Triple therapies were less effective than in adults, and proton pump inhibitor-based triple therapies have a similar efficacy irrespective of the duration. Recently, a new sequential treatment proved to be more efficacious than standard therapies. Recent data suggest that probiotics may maintain lower levels of H. pylori in the stomach, and in combination with antibiotics, probiotics may decrease adverse effects. Probiotics might constitute a low-cost, large-scale alternative solution applicable for populations at-risk for H. pylori colonization.

Italian cross-sectional growth charts for height, weight and BMI (2 to 20 yr)

The aim of this study is to extend to pre-school ages the Italian Society for Pediatric Endocrinology and Diabetes (SIEDP)-2002 growth charts for height, weight and body mass index (BMI), to obtain charts (SIEDP-2006) that apply to the Italian population from 2 to 20 yr of age, taken as a whole, or separately in two geographical areas (Central-North Italy and South Italy). The charts are based on a sample of about 70,000 subjects attending infant, primary and secondary schools, between 1994 and 2004. The distribution of the sample by gender, age and geographic area was roughly similar to that of Italian school population in the last decade of the 20th century. Height and weight were measured using portable Harpenden stadiometers and properly calibrated scales, respectively. SIEDP-2006 references are presented both as centiles and as LMS curves for the calculation of SD scores, and include the extra-centiles for overweight and obesity. Large differences in BMI growth pattern emerged between the SIEDP-2006, 2000 CDC and UK90 references: in Italy, BMI is higher and its distribution is more skewed during childhood and adolescence. At the end of growth, median values of the three references are similar, but the 97th centile of 2000 CDC charts is much higher and increases more steeply than that of SIEDP-2006 charts, which on the contrary reach a plateau. SIEDP-2006 references intend to supply pediatricians with a tool that avoids the use of charts that are outdated or that refer to other populations, and thus should be suitable for adequately monitoring the growth of their patients.

Identification of new variants of human BMP15 gene in a large cohort of women with premature ovarian failure

CONTEXT

Premature ovarian failure (POF) is a cause of female infertility characterized by primary (PA) or secondary amenorrhea (SA) and elevated gonadotropins. The pathogenesis is unknown in most cases. We recently reported two sisters with PA carrying a heterozygous mutation of BMP15 gene (locus Xp11.2), but the prevalence of BMP15 variations in the POF population is unknown.

OBJECTIVE

The objective of the study was to verify the involvement of BMP15 variations in a large POF population.

DESIGN AND SUBJECTS

Genetic screening of 166 unrelated patients with idiopathic POF (25 PA, 141 SA) and controls (group A: 95 women with menopause beyond 50 yr of age; group B: 86 women and 30 men from the general population) of Caucasian origin.

RESULTS

Investigation revealed four heterozygous variations affecting the proregion of BMP15. The previously reported p.Y235C mutation occurred in one and three novel variants in eight patients: two missense alterations (p.R68W in one case, p.A180T in five) and one insertion (p.262insLeu) in two cases. The p.262insLeu was found in five controls of group A, thus diminishing its potential biological impact, whereas the other three variants were not present in any of the controls. All new mutations were found in SA cases.

CONCLUSION

We describe the significant association of heterozygous BMP15 gene variants with the POF phenotype in humans (seven of 166 patients: 4.2%; P < 0.003 vs. controls). These findings are consistent with the critical role played by BMP15 in human folliculogenesis.

Improved efficacy of 10-Day sequential treatment for Helicobacter pylori eradication in children: a randomized trial

BACKGROUND & AIMS

The currently recommended first-line eradication treatment of Helicobacter pylori in children is usually successful in about 75%. Recently, in adults, a novel 10-day sequential treatment has achieved an eradication rate of 95%. The aim of the study was to assess the H pylori eradication rate of the sequential treatment regimen compared with conventional triple therapy in children.

METHODS

Seventy-eight consecutive children with H pylori infection were randomized to receive either sequential treatment (omeprazole plus amoxicillin for 5 days, followed by omeprazole plus clarithromycin plus tinidazole for another 5 days) (n = 38; 15 boys [39.5%]; median age, 11.0 years [range, 3.3-16 years]) or triple therapy (omeprazole, amoxicillin, and metronidazole) for 1 week (n = 37; 15 boys [40.5%]; median age, 9.9 years [range, 4.3-16 years]). H pylori infection was based on 2 out of 3 positive tests results: 13C-urea breath test, rapid urease test, and histologic analysis. Eradication was assessed by 13C-urea breath test 8 weeks after therapy.

RESULTS

Seventy-four patients completed the study. H pylori eradication was achieved in 36 children receiving sequential treatment (97.3%; 95% confidence interval, 86.2-99.5) and 28 children receiving triple therapy (75.7%; 95% confidence interval, 59.8-86.7) (P < .02). Compliance with therapy was good (>95%) in all.

CONCLUSIONS

Our study shows, for the first time in children, that 10-day sequential treatment achieves a higher eradication rate than standard triple therapy, which is consistent with the results of adult studies.

Final height in short polytransfused thalassemia major patients treated with recombinant growth hormone

We measured the final height (FH) of 25 short polytransfused thalassemia major (Th) patients (18 males) with a reduced GH reserve treated for 3.3 +/- 1.2 yr with recombinant GH (rhGH), 0.2 mg/kg/week sc. At baseline, all patients were clinically prepubertal; their chronological (CA) and bone ages (BA) were 13.6 +/- 2.0 and 11.4 +/- 1.6 yr, respectively. In 9 out of 18 males and 5 out of 7 females, the onset of puberty occurred spontaneously during the treatment. At the end of the rhGH administration, the height of the enrolled children was not significantly increased when calculated for CA (HxCA), while it was significantly decreased (p=0.004) when calculated for BA (HxBA); the BA increase (3.29 +/- 1.65 yr) was significantly higher (p<0.001) than the height age increase (2.16 +/- 0.98 yr). The FHxCA showed a significant increase (p=0.001) compared to both baseline and the end of therapy, while the FHxBA was significantly decreased (p<0.001) compared with the corresponding value at baseline. At the end of therapy, both HxCA and HxBA resulted positively related to the BA at baseline (r=0.50 and 0.42, p=0.012 and 0.034, respectively). FH was positively correlated with CA (r=0.63, p=0.001), BA (r=0.68, p<0.001) and HxBA (r=0.59, p=0.002) evaluated at baseline, and with both HxCA and HxBA (r=0.82 and 0.74, respectively, p<0.001), evaluated at the end of treatment. A negative correlation was found between FH and the length of treatment (r=-0.56, p=0.004). Our data seem to exclude that prolonged rhGH therapy could improve FH in Th patients; on the contrary, a negative effect may be hypothesized.

The acid-labile subunit of human ternary insulin-like growth factor-binding protein complex in girls with central precocious puberty before and during gonadotropin-releasing hormone analog therapy

The aim of the study was to evaluate serum acid-labile subunit (ALS) concentrations and their relationship with other parameters of the human ternary IGF-I-binding protein (IGFBP) complex in girls with central precocious puberty (CPP) before and after pharmacological arrest of puberty. We studied serum ALS, free IGF-I, total IGF-I, IGFBP-3 levels and IGFBP-3 protease activity in 13 girls, aged 1.6-7.8 yr (mean, 5.9 +/- 2.2), diagnosed as having CPP before and after 6 and 12 months of GnRH analog (GnRHa) therapy. The ALS SD score before treatment was high (1.4 +/- 0.72) and decreased significantly after 6 and 12 months of GnRHa therapy [0.4 +/- 0.54 (P < 0.01) and -0.4 +/- 0.61 (P < 0.01), respectively]. Serum IGF-I and IGFBP-3 were also increased before treatment, but both of these factors remained elevated after 6 and 12 months of GnRH-A therapy [IGF-I SD score, 3.20 +/- 1.64, 2.92 +/- 1.82, and 3.68 +/- 1.94 (P = NS), respectively; IGFBP-3 SD score, 1.02 +/- 0.53, 0.94 +/- 0.68, and 1.22 +/- 0.87 (P = NS), respectively]. Serum free IGF-I levels and IGFBP-3 proteolytic activity did not vary significantly from their pretreatment values during GnRHa therapy. In conclusion, serum ALS levels were elevated in girls with CPP and decreased significantly during the first year of GnRHa therapy. Serum IGF-I and IGFBP-3 levels were also increased before therapy, but their levels were not influenced by treatment. The ALS decrease seems to be the sole GH-dependent factor that parallels the decreases in steroid levels and growth velocity during GnRHa therapy.

A theoretical study of steric and electronic effects in the rhodium-catalyzed carbonylation reactions

We present a QM and QM/MM study of steric and electronic effects in the main steps of Rh-catalyzed carbonylation reactions. All the considered systems adopt a square-planar geometry prior to CH(3)I oxidative addition. As regards the octahedral complexes after CH(3)I oxidative addition, a comparison between the various models indicates that the energy gain due to the CH(3)I oxidative addition is reduced by the steric pressure of the substituents on the ligand. The substantially similar results obtained with the QM/MM and QM models indicate that electronic effects are not particularly relevant in determining the energetic of oxidative addition. As regards the P,P-Ph octahedral complex, the geometries in which the CO group is trans to the added CH(3) group, or trans to one of the P atoms, are of similar energy. A comparison between the various models indicates that the energy barrier of the CO insertion reaction is lowered by the presence of substituents on the chelating ligands. This effect is related to a relief of the steric pressure on the complex as the systems move from a six-coordinated octahedral geometry toward a five-coordinated square-pyramidal geometry. The energy barrier calculated for the P,S-Ph system is in rather good agreement with the experimental value, whereas that of the P,P-Ph system is somewhat underestimated. Inclusion of solvent effects with a continuum model leads to a slightly better agreement. The thermodynamic products adopt a square-pyramidal geometry with the COCH(3) group in the apical position.

Recombinant growth hormone treatment in short patients with thalassemia major: results after 24 and 36 months

Treatment with recombinant growth hormone (rhGH), 0.6 IU/kg/week s.c., previously successfully conducted for one year, was continued in 15 (Group A) and 8 (Group B) short thalassemia major patients with reduced GH reserve, for two and three years, respectively. In Group A, height for chronological age (Ht SDSCA) increased significantly (p = 0.021) from the start of treatment, but the positive effect was only apparent because of the concomitant slight worsening of height for bone age (Ht SDSBA). Median deltaHt SDSCA/deltaHt SDSBA was <1.0 with respect to both the start (0.87) and the end of the first year of rhGH therapy (0.89). IGF-I levels increased significantly (p = 0.043) compared with values both at the start and at the end of the first year of rhGH therapy. In Group B neither Ht SDSCA nor Ht SDSBA differed statistically from starting values, the former having a positive trend and the latter a negative one. Median deltaHt SDSCA/deltaHt SDSBA was 0.92 with respect to the start, and 0.94 with respect to the end of the second year. IGF-I levels increased significantly (p = 0.043) with respect to starting values. Our data show that the encouraging results described from the first year of rhGH treatment did not persist during the second and third years, and we conclude that this is because increase in bone age with continued treatment is equal to, or slightly greater than the height age increase. We propose that patients with thalassemia major with short stature should receive rhGH treatment for only one year, and that more prolonged treatment should be reserved for selected adolescents who have psychological problems due to shortness; for these patients growth acceleration could represent the main goal, even if this leads to a substantially unchanged or slightly decreased final height.

Management of puberty for optimal auxological results in beta-thalassaemia major

Short stature is present in a significant percentage of patients affected by beta-thalassaemia major. Growth failure of patients with thalassaemia is multifactorial. The most important contribution is attributed to the toxic effect of desferrioxamine and to endocrine disorders, due to iron overload. The commonest endocrine complication is hypogonadism. The growth pattern of patients with thalassaemia is characterized by normal growth during childhood, a deceleration of growth velocity around age 9-10 years, and a reduced pubertal growth spurt. In addition, reduced growth of the trunk is often present. Short stature and short trunk are more evident at pubertal age. Hypogonadism is usually considered responsible for the pubertal growth failure, as well as the aggravation of body disproportion at pubertal age. However, data suggest that pubertal height gain and final height are reduced in both patients with spontaneous puberty and patients with induced puberty. It is concluded that several aspects of peripubertal growth in patients with thalassaemia remain to be clarified.

Management of puberty in constitutional delay of growth and puberty

Constitutional delay of growth and puberty (CDGP) is the most common presenting form of short stature, but no single test can infallibly discriminate CDGP and isolated hypogonadotrophic hypogonadism. Management of puberty in CDGP aims to optimise not only growth maintaining body proportions and improving peak bone mass without impairing growth potential--but also well-being; for example, the distress boys often suffer because of their lack of growth and pubertal progression can affect their school performance and social relationships. Typical sex steroid treatments to induce puberty in boys with CDGP include testosterone (T) enanthate, T undecanoate, mixed T esters, T transdermal patches, and oxandrolone p.o. Compared with other regimens, short-course low-dose depot T i.m. is an effective, practical, safe, well tolerated, and inexpensive regimen. Some unresolved problems in management include optimal timing and dose of sex steroid treatment, the role of GH in CDGP, and the management of CDGP in girls.

Idiopathic short stature

Idiopathic short stature (ISS) is a term used to describe the status of children with short stature that cannot be attributed to a specific cause. Many children diagnosed as having ISS have partial GH insensitivity, which can result from disturbances at various points of the GH-IGF-I axis. Several clinical studies on spontaneous growth in ISS showed that adult height was almost in the range of target height. GH treatment led to adult height not significantly higher than the pretreatment predicted adult height in most reports. No metabolic side effects have been observed, even when the dose was higher than in GH deficiency. Manipulation of puberty with gonadotrophin releasing hormone analogues reported by a few authors in a small number of children has shown conflicting results. Long-term psychological benefits of GH therapy for short normal children have not been demonstrated to date.

Turner's syndrome

Turner syndrome (TS) is the most common sex-chromosome abnormality in females. Short stature and hypogonadism are the classical clinical findings. The spontaneous final height (FH) ranges between 139 and 147 cm, representing a growth deficit of about 20 cm with respect to the unaffected population. GH therapy improves FH and should be started during childhood at a high dose of about 1 IU/kg/week (range 0.6-2 IU/kg/week). Some authors advocate combined therapy with an anabolic steroid at various doses (e.g. oxandrolone 0.05-0.1 mg/kg/day). This treatment results in a significantly increased FH, a large proportion of treated girls reaching a FH of more than 150 cm. Gonadal function is compromised during adolescence in about 80% of girls with TS, whilst in about 20% pubertal development occurs spontaneously. Oestrogen therapy should be started at the age of 13-14 years in hypogonadic patients; early onset of treatment (before 12 years) seems to compromise FH. Other concerns in these patients are fertility and osteopenia.

Unresolved problems in optimal therapy of pubertal disorders in oncological and bone marrow transplanted patients

Specialised clinics for the long-term follow-up of survivors from childhood cancer have developed over recent years. The problems encountered among patients who received multiple chemotherapy and radiotherapy can be challenging and require high expertise and close collaboration among different professionals (e.g. oncologists, endocrinologists, radiotherapists, psychologists). Endocrine disorders are often seen, particularly among those who received cranial radiotherapy or gonadotoxic chemotherapy; puberty can be affected and the spectrum of disorders may range from precocious or accelerated puberty to delayed, arrested or even absent pubertal development. Growth impairment can be multifactorial and growth hormone deficiency is an important but probably not the only factor involved. Many questions remain about the optimal management of this group of young patients. In the consensus guidelines that follow the overview an attempt is made to help optimise patients' growth and puberty by suggesting practical clinical approaches to some of the most challenging issues.

A possible mechanism for enantioselectivity in the chiral epoxidation of olefins with

The origin of enantioselectivity in the Jacobsen-Katsuki reaction has been investigated by applying density functional calculations in combination with molecular mechanics methodologies. The calculations suggest that a high enantiomeric excess is connected to three specific features: 1) a chiral diimine bridge, which induces folding of the salen ligand(H2salen = bis(salicylidene)ethylenediamine), and hence the formation of a chiral pocket; 2) bulky groups at the 3,3'-positions of the salen ligand, which cause a preferential approach from the side of the aromatic rings; and 3) pi conjugation of the olefinic double bond, which confers regioselectivity and, consequently, enantioselectivity. In combination with experimental studies, the model also provides a rationale for the decrease in ee values when one of these components is missing.

The effect of different growth hormone administration frequencies on growth in growth hormone-deficient patients

In two different groups of clinically prepubertal children (bone age </=8 years) with isolated growth hormone deficit we have evaluated either if the substitutive therapy administered by pump (permitting between 20.00 and 08.00 h the association of continuous and intermittent subcutaneous growth hormone administration) could improve growth (study A) or if a 3 times/week schedule treatment could be performed without any negative effect on growth with respect to 6 injections/week (study B). All patients had been previously successfully treated for at least 2 years by the same dose used during both studies (0.6 IU/kg/week) administered at bedtime 6 times/week. Study A: Each child underwent at bedtime both pump administration (6 months) and single daily injection (6 months). The circulating IGF-I pattern as well as the growth velocity and the ratio bone age increase/height age increase did not differ during the two treatment regimens. Study B: No differences were observed in auxological parameters during the treatment schedule on 3 times/week compared to the previous year on 6 times/week.

IN CONCLUSION

Our treatment, consisting of the association of continuous and intermittent subcutaneous growth hormone administration, did not improve growth velocity with respect to single daily subcutaneous injection; the growth hormone administration 3 times/week, starting at the 3rd year of substitutive therapy or later, seems to have no negative effect on growth with respect to 6 injections/week.

Stereoselectivity and chiral recognition in copper(I) olefin complexes with a chiral diamine

Trigonal copper(I) complexes of the chiral bidentate ligand (1S,2S)-N,N'-Bis-(mesitylmethyl)-1,2-diphenyl-1,2-ethanediamine ((S,S)-1) have been prepared with hydrocarbon olefins, as well as with allylic alcohols and ethers. The stereochemistry of the complexes has been investigated by 1H NMR spectroscopy and by combined quantum mechanics and molecular mechanics (QM/MM) computational methods. The coordinated chiral nitrogen atoms can display equal (R, R) or opposite (R, S) configuration, the latter being disfavored if steric hindrance is present above and below the coordination plane. Although the complexes exist as rapidly equilibrated mixtures of stereoisomers, one of these is often dominant, and prochiral olefins are coordinated with high enantioface selection. In addition, the [(S,S)-1]-Cu+ fragment selectively recognizes the R enantiomer of secondary allylic alcohols and ethers, as confirmed by the X-ray crystal structure analysis of the adduct with (R)-1-buten-3-ol. The reasons for the observed selectivities have been elucidated, and lead to some implications which are consistent with the enantioselection observed in catalytic cyclopropanation reactions promoted by copper complexes of the same ligand.

Radical Intermediates in the Jacobsen - Katsuki Epoxidation

Insight into the controversial mechanism of the Mn - salen-catalyzed epoxidation of olefins is provided in a theoretical study based on density functional theory. The calculations suggest that radical species A, but not manganaoxetanes B, are likely candidates for viable intermediates.