Class A PBPs have a distinct and unique role in the construction of the pneumococcal cell wall.

In oval-shaped Streptococcus pneumoniae, septal and longitudinal peptidoglycan syntheses are performed by independent functional complexes: the divisome and the elongasome. Penicillin-binding proteins (PBPs) were long considered the key peptidoglycan-synthesizing enzymes in these complexes. Among these were the bifunctional class A PBPs, which are both glycosyltransferases and transpeptidases, and monofunctional class B PBPs with only transpeptidase activity. Recently, however, it was established that the monofunctional class B PBPs work together with transmembrane glycosyltransferases (FtsW and RodA) from the shape, elongation, division, and sporulation (SEDS) family to make up the core peptidoglycan-synthesizing machineries within the pneumococcal divisome (FtsW/PBP2x) and elongasome (RodA/PBP2b). The function of class A PBPs is therefore now an open question. Here we utilize the peptidoglycan hydrolase CbpD that targets the septum of S. pneumoniae cells to show that class A PBPs have an autonomous role during pneumococcal cell wall synthesis. Using assays to specifically inhibit the function of PBP2x and FtsW, we demonstrate that CbpD attacks nascent peptidoglycan synthesized by the divisome. Notably, class A PBPs could process this nascent peptidoglycan from a CbpD-sensitive to a CbpD-resistant form. The class A PBP-mediated processing was independent of divisome and elongasome activities. Class A PBPs thus constitute an autonomous functional entity which processes recently formed peptidoglycan synthesized by FtsW/PBP2×. Our results support a model in which mature pneumococcal peptidoglycan is synthesized by three functional entities, the divisome, the elongasome, and bifunctional PBPs. The latter modify existing peptidoglycan but are probably not involved in primary peptidoglycan synthesis.

Class A PBPs: It is time to rethink traditional paradigms.

Until recently, class A penicillin-binding proteins (aPBPs) were the only enzymes known to catalyze glycan chain polymerization from lipid II in bacteria. Hence, the discovery of two novel lipid II polymerases, FtsW and RodA, raises new questions and has consequently received a lot of attention from the research community. FtsW and RodA are essential and highly conserved members of the divisome and elongasome, respectively, and work in conjunction with their cognate class B PBPs (bPBPs) to synthesize the division septum and insert new peptidoglycan into the lateral cell wall. The identification of FtsW and RodA as peptidoglycan glycosyltransferases has raised questions regarding the role of aPBPs in peptidoglycan synthesis and fundamentally changed our understanding of the process. Despite their dethronement, aPBPs are essential in most bacteria. So, what is their function? In this review, we discuss recent progress in answering this question and present our own views on the topic.

Physiological factors influencing diabetes control in type 1 diabetes children with insulin pumps from diagnosis.

BACKGROUND: The aim of this study was to identify the physiological factors influencing diabetes control in children with type 1 diabetes (T1D) using continuous subcutaneous insulin infusion (CSII) from diabetes diagnosis. METHODS: This study focused on 163 children (81 boys) initiated with CSII within 2 weeks after T1D recognition and treated for at least 3 years. We analysed fasting C-peptide, GADA, ICA, IA2A, BMI z-score, total daily dose, and basal insulin. Patients were divided into groups according to their metabolic control: 7.5% > HbA1c ≥ 7.5% at the end of the study. RESULTS: At the end of the follow-up, patients with HbA1c <7.5%, had a lower HbA1c level at diagnosis (11.7% vs 12.6%; P = 0.018), lower HbA1c level at both the first-year (6.7% vs 7.3%; P = 0.000) and the second-year (6.8% vs.7.7%; P = 0.000) follow-up, and a lower GADA level (P = 0.001). A multiple logistic regression analysis showed that HbA1c at diagnosis (P = 0.012), HbA1c at first year (P = 0.000), HbA1c at second year (P = 0.000), age at diagnosis (P = 0.047), GADA (P = 0.031), and basal insulin at third year (P = 0.032), influenced HbA1c <7.5% at the third year of follow-up. At the end of the study, 76% of patients started with CSII at the age <10 years and 49% of subjects initiated with CSII at the age ≥10 years achieved HbA1c ≤7.5%. CONCLUSIONS: This study shows that for those who initiated CSII at T1D onset, younger age, less intense autoimmune process, a low HbA1c at recognition, and good diabetes control during the first year of treatment were associated with long-term optimal glycaemic control.

The additional dose of insulin for high-protein mixed meal provides better glycemic control in children with type 1 diabetes on insulin pumps: randomized cross-over study.

BACKGROUND: Delivery of insulin for high-protein low-fat meals with carbohydrates on the basis of carbohydrates leads to higher late postprandial glycemia. Studies with mixed meals demonstrated lower blood glucose level after dual wave bolus. The objective of our study was to assess the impact of additional dose of insulin in dual wave bolus for high-protein mixed meal on the postprandial glycemia. MATERIALS AND METHODS: We performed a randomized, double-blind, two-way cross-over study, including 58 children with type 1 diabetes, aged 14.7 ± 2.2 years. Participants were randomly assigned into two treatment orders: NORMAL-DUAL or DUAL-NORMAL BOLUS. They consumed standardized high-protein, low-fat meals with carbohydrates. The primary outcome was postprandial glycemia (PPG) based on capillary blood glucose measurements (CBGM). The secondary outcomes were the frequency of hypoglycemia, area under glucose curve, mean amplitude of glycemic excursion (MAGE) and glycemic rise. RESULTS: PPG assessed at 180 min was significantly lower when dual wave bolus was delivered (NORMAL 162 mg/dL [9 mmol/L] vs DUAL 130.0 mg/dL [7.22 mmol/L]; P = .004). There were no differences in CBGM between both groups at 60 and 120 min. We found differences between the groups in MAGE at 120 min (NORMAL 82.86 mg/dL [4.6 mmol/L] versus DUAL 54.76 mg/dL [3.04 mmol/L]; P = .0008). We observed no differences in the number of hypoglycemic episodes in both groups. CONCLUSION: Applying an additional dose of insulin in dual wave bolus for high-protein mixed meal improved PPG. We observed no statistically significant increase in the number of hypoglycemic episodes associated with this intervention.

The course of glucose intolerance in children with cystic fibrosis: a retrospective study - preliminary report.

UNLABELLED: Diabetes is a common and severe complication of cystic fibrosis. If unrecognized, the condition not only causes deterioration of pulmonary function and failure to gain weight, but also a six-fold increase in mortality. AIM: 1. To evaluate the course of abnormal glucose tolerance and cystic fibrosis-related diabetes (CFRD), as well as the effects of treating these conditions in children with cystic fibrosis. 2. To analyze the association between the classes of mutations in both alleles of the CFTR gene and glucose intolerance. MATERIALS AND METHODS: analysis was undertaken of the clinical records of 12 children (from the years 2002 to 2014), who were under the care of the Diabetes Outpatient Clinic at the Medical University of Warsaw and the Cystic Fibrosis Centre of the Institute of Mother and Child in Warsaw. The patients were divided into groups based on glucose tolerance categories in the Oral Glucose Tolerance Test (impaired glucose tolerance - IGT, cystic fibrosis related diabetes without fasting hyperglycemia - CFRD FH⁻ or with fasting hyperglycemia - CFRD FH⁺). The mean age of the children who were referred to the Diabetes Outpatient Clinic was 12.09 ± 3.57 years and the mean HbA1c at the baseline versus the end of the follow up was 6.16 ± 1,77% versus 6.03 ± 1.05%, respectively. We used the continuous glucose monitoring system (CGMS) for the diagnostics of 4 patients. The mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene were investigated in all the patients. All the children had mutations in at least one allele of the CFTR gene belonging to class I or II. Six (6/12) patients were homozygous, and 3 (3/12) patients heterozygous for the Phe508del (former F508del) mutation. Three children had other mutations (1717-1G>A/2183AA-G, R553X/3380delGAAG, G542X/2143delT). RESULTS: In our study group we recognized impaired glucose tolerance (IGT) in 7 (7/12) patients and cystic fibrosis-related diabetes (CFRD) in 5 (5/12) patients; there were 4 patients with CFRD FH⁺ and 1 patient with CFRD FH⁻. During follow up we observed IGT deterioration of glucose tolerance towards CFRD FH⁻ in 4(4/7) patients. Eight (8/12) patients were on functional insulin therapy, five of them (5/8) used insulin pumps. The remaining patients (4 individuals - 4/12), who were in good condition and on a high-glycemic index product restricted diet, did not require insulin. In the group treated with insulin we observed improvement in BMI z-scores (from-1.14 to -0.70). CONCLUSIONS: Glucose tolerance in children with cystic fibrosis deteriorates with age. Patients in a good condition and with good compliance to a low-glycemic index product diet, start insulin therapy later. Patients with a severe course of cystic fibrosis and diabetes require immediate insulin implementation. Insulin treatment improves their nutritional status. A continuous glucose monitoring system is a useful diagnostic tool which can be taken into account in therapeutic decisions. Prospective studies on the pediatric population with cystic fibrosis are needed in Poland for a better analysis of the associations between abnormal glucose tolerance, the class of mutation in the CFTR gene and the impact of glucose intolerance treatment on the clinical status of the patients.

Environmental factors affecting management of type 1 diabetes in children below the age of 10.

INTRODUCTION: The way parents manage diabetes of their small children and environmental influence are crucial for maintaining glycemic control. The aim of the study was to assess environmental factors affecting metabolic control of young children with T1D treated with insulin pumps. MATERIAL AND METHODS: Parents of children with T1D under the age of 10 years completed: General Self-Efficacy Scale, Parental Diabetes Quality of Life Questionnaire, Beck Depression Inventory and a questionnaire on socioeconomic factors. RESULTS: There were analyzed 165 questionnaires. 66% of children achieved HbA1c <7.5% (<58mmol/mol). Factors associated with HbA1c≥7.5% (≥58mmol/mol) in the multiple logistic regression: single-parent families (p=0.003), low income <250EURO (p=0.017), parental education (p<0.05), snacking without parents' permission (p=0.0006) and in parents of children ≥6 year of age - quality of life (p=0.037). In families of children <6 year of age, parents had higher self-efficacy than parents of children ≥6 year of age (p=0.046). CONCLUSIONS: Parents of young children are not homogeneous group and face different challenges. Young children of parents withlower education level and living in single-parent families are at high risk of poor diabetes management. More attention should be paid to the problem of young children snacking without parents' permission. ABBREVIATIONS: BDI - Beck Depression Inventory, CI-Confidence Intervals, GSES - General Self-Efficacy Scale, HbA1c - glycated hemoglobin, OR- Odds Ratio, PDQOLQ - Parental Diabetes Quality of Life Questionnaire, T1D - type 1 diabetes.

Impact of ELKa, the Electronic Device for Prandial Insulin Dose Calculation, on Metabolic Control in Children and Adolescents with Type 1 Diabetes Mellitus: A Randomized Controlled Trial.

Background. The ELKa system is composed of computer software, with a database of nutrients, and a dedicated USB kitchen scale. It was designed to automatize the everyday calculations of food exchanges and prandial insulin doses. Aim. To investigate the influence of the ELKa on metabolic control in children with type 1 diabetes mellitus (T1DM). Methods. A randomized, parallel, open-label clinical trial involved 106 patients aged <18 years with T1DM, HbA1C ≤ 10%, undergoing intensive insulin therapy, allocated to the intervention group, who used the ELKa (n = 53), or the control group (n = 53), who used conventional calculation methods. Results. After the 26-week follow-up, the intention-to-treat analysis showed no differences to all endpoints. In per protocol analysis, 22/53 (41.5%) patients reporting ELKa usage for >50% of meals achieved lower HbA1C levels (P = 0.002), lower basal insulin amounts (P = 0.049), and lower intrasubject standard deviation of blood glucose levels (P = 0.023) in comparison with the control. Moreover, in the intervention group, significant reduction of HbA1C level, by 0.55% point (P = 0.002), was noted. No intergroup differences were found in the hypoglycemic episodes, BMI-SDS, bolus insulin dosage, and total daily insulin dosage. Conclusions. The ELKa system improves metabolic control in children with T1DM under regular usage. The trial is registered at ClinicalTrials.gov, number NCT02194517.

Food exchange estimation by children with type 1 diabetes at summer camp.

BACKGROUND: As exchange counting poses difficulty for children with type 1 diabetes (T1D) attending diabetes camps, they often guesstimate food amount without performing an exchange calculation. The aim of the study was to compare the accuracy of estimation with exchange counting using the mobile food exchange calculator (MFEC). METHODS: During a summer camp, 25 children with T1D on pumps estimated the number of carbohydrate (CE) and fat/protein exchanges (FPE) appropriate for main meals. Afterwards, the number of exchanges was counted with MFEC and electronic scales. RESULTS: There was a difference between CE (p<0.0001) and FPE (p<0.0001) estimations and counting using MFEC. The youth miscalculated the true values of ≥1 CE and ≥1 FPE by 31% and 23%, respectively. They more often underestimated than overestimated CE and FPE (p<0.0001). The estimation error increased with younger age. CONCLUSIONS: Carbohydrate counting caused significant error in the exchange number. The use of MFEC facilitates correct exchange calculation. Patients should weigh food and calculate exchanges themselves using mobile applications.

High Frequency of Diabetic Ketoacidosis in Children with Newly Diagnosed Type 1 Diabetes.

AIM: The aim of this study was to evaluate the incidence of diabetic ketoacidosis in children and adolescents with newly diagnosed type 1 diabetes in 2006-2007 and 2013-2014. METHOD: The study group consisted of 426 children aged 0-18 years with type 1 diabetes onset admitted to our hospital in 2006-2007 (group A) and 2013-2014 (group B). The study comprised the analysis of medical and laboratory records from patients' medical charts and the electronic database. RESULTS: There was no difference between groups A and B in the percentage of children admitted with diabetic ketoacidosis (25% versus 28%, resp., P = 0.499). Among children with diabetic ketoacidosis, severe metabolic decompensation (pH < 7.1) appeared in similar frequency in groups A and B (28% versus 30%, resp., P = 0.110). In group B, children with diabetic ketoacidosis were statistically younger compared to patients without ketoacidosis (P = 0.015) and had higher HbA1c levels (P = 0.006). In both groups, a 2-fold increase in diabetic ketoacidosis was noted in children under the age of 3, compared to overall frequency. CONCLUSION: No decrease in diabetic ketoacidosis has been noted in the recent years. Although the prevalence and severity of diabetic ketoacidosis remain stable, they are unacceptably high. The youngest children are especially prone to ketoacidosis.