The MiniMed 780G automated insulin delivery system adapts to substantial changes in daily routine: Lessons from real world users during Ramadan.

AIM: To report on the effectiveness and safety of the MiniMed 780G automated insulin delivery system in real-world users during the month of Ramadan. MATERIALS AND METHODS: CareLink Personal data were extracted from MiniMed 780G system users from the Gulf region. Users were included if they had ≥10 days of sensor glucose data during the month of Ramadan 2022 as well as in the month before and after. For the main analysis, continuous glucose monitoring endpoints were aggregated per month and were reported by time of day (daytime: 05.31-18.00 h, and night-time). Additional analyses were performed to study the pace at which the algorithm adapts. RESULTS: Glycaemic control was well kept in the 449 included users (mean sensor glucose = 152.6 ± 18.7 mg/dl, glucose management indicator = 7.0 ± 0.4%, time in range = 70.7 ± 11.0%, time below 70 mg/dl = 2.3 ± 2.3%). Albeit some metrics differed from the month before (p < .0001 for all), absolute differences were very small and considered clinically irrelevant. During Ramadan, there was no increased risk of hypoglycaemia during daytime (time below 70 mg/dl = 2.3 ± 2.4%), time in range was highest during daytime (80.0 ± 10.7%, night: 60.4 ± 15.3%), while time above 180 mg/dl was highest during night-time (37.3 ± 16.3%, day: 17.7 ± 10.7%). The algorithm adapted immediately upon lifestyle change. CONCLUSION: The MiniMed 780G automated insulin delivery system is effective, safe and fast in adapting to the substantial changes that occur in the lifestyle of people with type 1 diabetes during Ramadan.

The significance of coefficient of variation as a measure of hypoglycaemia risk and glycaemic control in real world users of the automated insulin delivery MiniMed 780G system.

AIM: Use of the MiniMed 780G system (MM780G) can result in a reduction in mean and standard deviation (SD) of sensor glucose (SG) values. We assessed the significance of the coefficient of variation (CV) as a measure of hypoglycaemia risk and glycaemic control. MATERIALS AND METHODS: Data from 10 404 MM780G users were analysed using multivariable logistic regression to assess the contribution of CV to (a) hypoglycaemia risk, measured as not reaching target <1% for time below range (TBR), and (b) achieving targets of time-in-range (TIR) >70% and glucose management indicator <7%. CV was compared with SD and low blood glucose index. To assess the relevance of CV <36% as a therapeutic threshold, we identified the CV cut-off point that optimally discriminated users at risk of hypoglycaemia. RESULTS: The contribution of CV was the smallest in terms of risk of hypoglycaemia (vs. low blood glucose index and SD) and TIR and glucose management indicator targets (vs. SD). In all cases the models with SD showed the best fit. A CV <43.4% (95% CI: 42.9-43.9) was the optimal cut-off point with a correct classification rate of 87.2% (vs. 72.9% for CV <36%). CONCLUSION: For MM780G users, CV is a poor marker for hypoglycaemia risk and glycaemic control. We recommend using, for the former, TBR and whether the TBR target is met (and not using CV <36% as a therapeutic threshold for hypoglycaemia); for the latter, TIR, time above range, whether targets are met and a discrete description of mean SG and SD of SG values.

Twelve-month results of the ADAPT randomized controlled trial: Reproducibility and sustainability of advanced hybrid closed-loop therapy outcomes versus conventional therapy in adults with type 1 diabetes.

AIMS: To reassess the 6-month efficacy and to assess the 12-month sustained efficacy of the MiniMed™ 780G advanced hybrid closed-loop automated insulin delivery (AID) system compared to multiple daily injections plus intermittently scanned glucose monitoring (MDI+isCGM) in people with type 1 diabetes not meeting glucose targets. METHODS: The ADAPT study was a prospective, multicentre, open-label, randomized control trial in people with type 1 diabetes, with a glycated haemoglobin (HbA1c) concentration of at least 8.0% (64 mmol/mol), on MDI+isCGM therapy. After a 6-month study phase, participants randomized at baseline to MDI+isCGM switched to AID (SWITCH) while the others continued AID therapy (SUSTAIN) for an additional 6 months. The primary endpoint of this continuation phase was the within-group change in mean HbA1c between 6 and 12 months, with superiority in the SWITCH group and noninferiority in the SUSTAIN group (ClinicalTrials.gov: NCT04235504). RESULTS: A total of 39 SWITCH and 36 SUSTAIN participants entered the continuation phase. In the SWITCH group, HbA1c was significantly decreased by -1.4% (95% confidence interval [CI] -1.7% to -1.1%; P < 0.001) from a mean ± SD of 8.9% ± 0.8% (73.9 ± 8.6 mmol/mol) at 6 months to 7.5% ± 0.6% (58.5 ± 6.9 mmol/mol) at 12 months. Mean HbA1c increased by 0.1% (95% CI -0.05% to +0.25%), from 7.3% ± 0.6% (56.5 ± 6.7 mmol/mol) to 7.4% ± 0.8% (57.7 ± 9.1 mmol/mol) in the SUSTAIN group, meeting noninferiority criteria. Three severe hypoglycaemia events occurred in two SWITCH participants during the continuation phase. CONCLUSION: ADAPT study phase glycaemic improvements were reproduced and sustained in the continuation phase, supporting the early adoption of AID therapy in people with type 1 diabetes not meeting glucose targets on MDI therapy.

Real-world performance of the MiniMed 780G advanced hybrid closed loop system in Latin America: Substantial improvement in glycaemic control with each technology iteration of the MiniMed automated insulin delivery system.

AIM: We studied real-world performance of MiniMed (MM) 780G system users from Argentina, Brazil, Colombia and Chile (geographical analysis), and the effect of each technology iteration of the MM system on glycaemic control (technology iteration analysis). MATERIALS AND METHODS: CareLink data from August 2020 to September 2022 were extracted. Endpoints included continuous glucose monitoring metrics. For the geographical analysis, aggregated endpoints for MM780G system users were calculated. For the technology iteration analysis, MM780G system user outcomes were compared with outcomes when the same individuals were still using the MM640G or MM670G system. RESULTS: On average, 1025 MM780G system users from the geographical analysis were followed for 136 (SD 135) days, spent 91.5 (14.3)% in advanced hybrid closed loop, showed a glucose management indicator (GMI) of 6.7 (0.3)%, a time in range between 70 and 180 mg/dl (TIR) of 76.5 (9.0)%, and a time below range 70 mg/dl (TBR) of 2.7 (2.1)%. The percentage of users reaching targets of GMI <7%, TIR >70% and TBR <4% was 80.8%, 78.1% and 80.1%, respectively. The technology iteration analysis on users transitioning from MM640G to MM780G system (N = 381) showed 0.4% decrease in GMI (7.1% to 6.7%, p < .0001), 10.7% increase in TIR (65.9% to 76.6%, p < .0001), while TBR remained. The percentage of insulin delivered automatically increased as well (47.5%-57.7%, p < .0001). Users transitioning from MM670G system (N = 78) showed a similar but less pronounced pattern. CONCLUSIONS: Real-world Latin American MM780G users on average showed good glucose control, achieving international targets. Glycaemic control increased with every technology iteration of the MM system, providing more automation each time.

In-house standards derived from doping peptides: Enzymatic and serum stability and degradation profile of GHRP and GHRH-related peptides.

Matrix effect and sample pretreatment significantly affect the percentage recovery of peptides in biological matrices, affecting the method robustness and accuracy. To counteract this effect, an internal standard (IS) is used; however, in most cases this is not available, which limits the analytical method. It is important to identify short peptides that can be used as ISs in the quantification of peptides in biological matrices. In this study, doping peptides GHRP-4, GHRP-5, GHRP-6, Sermorelin (1-11), Sermorelin (13-20) and Sermorelin (22-29) were synthesized using solid-phase peptide synthesis. Treatment with human blood, trypsin and chymotrypsin was used to determine the stability of the peptides. Products were evaluated using the high-performance liquid chromatography-diode array detector (HPLC-DAD) method. The analytical methodology and sample pretreatment were effective for the analysis of these molecules. A unique profile related to protein binding and enzymatic stability of each peptide was established. GHRP-4, GHRP-6 and Sermorelin (22-29) can be considered as in-house ISs as they were stable to enzyme and blood treatment and can be used for the quantification of peptides in biological samples. Peptides GHRP-6 and Sermorelin (22-29) were used to analyse a dimeric peptide (26 [F] LfcinB (20-30)2 ) in four different matrices to test these peptides as in-house IS.

Predictors of time in target glucose range in real-world users of the MiniMed 780G system.

AIM: Automated insulin delivery systems have improved glycaemic control in people with type 1 diabetes mellitus. The analysis investigated predictors of improved sensor glucose time-in-range (TIR; 70-180 mg/dl) based on real-world use of the MiniMed 780G advanced hybrid closed-loop (AHCL) system. METHODS: Data uploaded by MiniMed 780G system users from August 2020-July 2021 were analysed using univariate and multivariable models to identify baseline, demographic and system use characteristics associated with TIR after AHCL initiation (post-AHCL). System settings associated with improved TIR post-AHCL were identified and their impact on time below range (TBR, <70 mg/dl) post-AHCL was explored. RESULTS: In total, 12 870 users were included, of which 2977 had baseline sensor glucose data. Baseline TIR and time in AHCL (defined as the percentage of time the system was in Auto-mode) were positively associated with TIR post-AHCL with larger values predicting greater mean TIR post-AHCL. Characteristics inversely associated with TIR post-AHCL included the percentage of daily basal insulin dose, daily autocorrection dose, number of daily AHCL exits triggered by the system and number of daily alarms, wherein larger values of these characteristics predicted lower mean TIR post-AHCL. System settings that predicted the largest mean TIR post-AHCL were active insulin time of 2 h and glucose target of 100 mg/dl. Active insulin time was not associated with TBR post-AHCL. CONCLUSION: Modifiable factors, including optimized pump settings, can allow users to achieve glycaemic targets with >80% TIR. The findings from this analysis will potentially guide the optimal use of the MiniMed 780G system and facilitate meaningful improvements in safe glycaemic control.

Comparison of MiniMed 780G system performance in users aged younger and older than 15 years: Evidence from 12 870 real-world users.

AIM: To investigate real-world glycaemic outcomes and goals achieved by users of the MiniMed 780G advanced hybrid closed loop (AHCL) system aged younger and older than 15 years with type 1 diabetes (T1D). MATERIALS AND METHODS: Data uploaded by MiniMed 780G system users from 27 August 2020 to 22 July 2021 were aggregated and retrospectively analysed based on self-reported age (≤15 years and >15 years) for three cohorts: (a) post-AHCL initiation, (b) 6-month longitudinal post-AHCL initiation and (c) pre- versus post-AHCL initiation. Analyses included mean percentage of time spent in AHCL and at sensor glucose ranges, insulin delivered and the proportion of users achieving recommended glucose management indicator (GMI < 7.0%) and time in target range (TIR 70-180 mg/dl > 70%) goals. RESULTS: Users aged 15 years or younger (N = 3211) achieved a GMI of 6.8% ± 0.3% and TIR of 73.9% ± 8.7%, while spending 92.7% of time in AHCL. Users aged older than 15 years (N = 8874) achieved a GMI of 6.8% ± 0.4% and TIR of 76.5% ± 9.4% with 92.3% of time in AHCL. Time spent at less than 70 mg/dl was within the recommended target of less than 4% (3.2% and 2.3%, respectively). Similar outcomes were observed for each group (N = 790 and N = 1642, respectively) in the first month following AHCL initiation, and were sustained over the 6-month observation period. CONCLUSIONS: This real-world analysis shows that more than 75% of users with T1D aged 15 years or younger using the MiniMed 780G system achieved international consensus-recommended glycaemic control, mirroring the achievements of the population aged older than 15 years.

Assessment of the determinants of changes and test-retest reliability in the 6-min walk test performance over a 4-month period in healthy 6-12-year-old children.

PURPOSE: The purpose of the study is to establish the determinants of change in 6-min walk test (6MWT) performance observed in children aged 6-12 years over a 4-month period, and to provide test-retest reliability (4 months) to establish the minimal detectable change (MDC). METHODS: Healthy children aged 6-12 years performed two 6MWT trials separated by a period of 4 months. Multiple linear regression analysis was performed to estimate the percentage of variance explained by the variables potentially predictive of the change in the 6MWT. We employed the intraclass correlation coefficient to assess test-retest reliability. RESULTS: Fifty-nine children (28 boys and 31 girls) were assessed. The change in distance covered during the 6MWT was significantly correlated with the growth in their height (r = 0.679; p < 0.05) and the change in their weight (r = 0.473; p < 0.05). Multiple linear regression analysis shows that the change in distance covered in the 6MWT was only explained by its growth in height (46.0% explained variance). The test-retest reliability was fair-good. After 4 months, we established a 12% change from the initial measurement (79.69 m) as the MDC for a 90% confidence level (MDC90). CONCLUSIONS: The distance covered in the 6MWT improved as the children's age, weight and height increased. The growth children's height was the most important predictor of change in distance covered in the 6MWT. An increase of at least 79.69 m (MDC90) in distance covered in the 6MWT is necessary to attribute the improvement to an intervention and not to the individual's growth.

Real-world performance of the MiniMed™ 670G system in Europe.

AIM: To evaluate the real-world performance of the MiniMed 670G system in Europe, in individuals with diabetes. MATERIALS AND METHODS: Data uploaded from October 2018 to July 2020 by individuals living in Europe were aggregated and retrospectively analysed. The mean glucose management indicator (GMI), percentage of time spent within (TIR), below (TBR) and above (TAR) glycaemic ranges, system use and insulin consumed in users with 10 or more days of sensor glucose data after initial Auto Mode start were determined. Another analysis based on suboptimally (GMI > 8.0%) and well-controlled (GMI < 7.0%) glycaemia pre-Auto Mode initiation was also performed. RESULTS: Users (N = 14 899) spent a mean of 81.4% of the time in Auto Mode and achieved a mean GMI of 7.0% ± 0.4%, TIR of 72.0% ± 9.7%, TBR less than 3.9 mmol/L of 2.4% ± 2.1% and TAR more than 10 mmol/L of 25.7% ± 10%, after initiating Auto Mode. When compared with pre-Auto Mode initiation, GMI was reduced by 0.3% ± 0.4% and TIR increased by 9.6% ± 9.9% (P < .0001 for both). Significantly improved glycaemic control was observed irrespective of pre-Auto Mode GMI levels of less than 7.0% or of more than 8.0%. While the total daily dose of insulin increased for both groups, a greater increase was observed in the latter, an increase primarily due to increased basal insulin delivery. By contrast, basal insulin decreased slightly in well-controlled users. CONCLUSIONS: Most MiniMed 670G system users in Europe achieved TIR more than 70% and GMI less than 7% while minimizing hypoglycaemia, in a real-world environment. These international consensus-met outcomes were enabled by automated insulin delivery meeting real-time insulin requirements adapted to each individual user.

Designing Chimeric Peptides: A Powerful Tool for Enhancing Antibacterial Activity.

Chimeric peptides containing short sequences derived from bovine Lactoferricin (LfcinB) and Buforin II (BFII) were synthetized using solid-phase peptide synthesis (SPPS) and characterized via reversed-phase liquid chromatography and mass spectrometry. The chimeras were obtained with high purity, demonstrating their synthetic viability. The chimeras' antibacterial activity against Gram-positive and Gram-negative strains was evaluated. Our results showed that all the chimeras exhibited greater antibacterial activity against the evaluated strains than the individual sequences, suggesting that chemical binding of short sequences derived from AMPs significantly increased the antibacterial activity. For each strain, the chimera with the best antibacterial activity exerted a bacteriostatic and/or bactericidal effect, which was dependent on the concentration. It was found that: (i) the antibacterial activity of a chimera is mainly influenced by the linked sequences, the palindromic motif RLLRRLLR being the most relevant one; (ii) the inclusion of a spacer between the short sequences did not significantly affect the chimera's synthesis process; however, it enhanced its antibacterial activity against Gram-negative and Gram-positive strains; on the other hand, (iii) the replacement of Arg with Lys in the LfcinB or BFII sequences improved the chimeras' synthesis process without significantly affecting their antibacterial activity. These results illustrate the great importance of the synthesis of chimeric peptides for the generation of promising antibacterial peptides.

Peptides Derived from (RRWQWRMKKLG)2-K-Ahx Induce Selective Cellular Death in Breast Cancer Cell Lines through Apoptotic Pathway.

The effect on the cytotoxicity against breast cancer cell lines of the substitution of 26Met residue in the sequence of the Bovine Lactoferricin-derived dimeric peptide LfcinB (20-30)2: (20RRWQWRMKKLG30)2-K-Ahx with amino acids of different polarity was evaluated. The process of the synthesis of the LfcinB (20-30)2 analog peptides was similar to the original peptide. The cytotoxic assays showed that some analog peptides exhibited a significant cytotoxic effect against breast cancer cell lines HTB-132 and MCF-7, suggesting that the substitution of the Met with amino acids of a hydrophobic nature drastically enhances its cytotoxicity against HTB-132 and MCF-7 cells, reaching IC50 values up to 6 µM. In addition, these peptides have a selective effect, since they exhibit a lower cytotoxic effect on the non-tumorigenic cell line MCF-12. Interestingly, the cytotoxic effect is fast (90 min) and is maintained for up to 48 h. Additionally, through flow cytometry, it was found that the obtained dimeric peptides generate cell death through the apoptosis pathway and do not compromise the integrity of the cytoplasmic membrane, and there are intrinsic apoptotic events involved. These results show that the obtained peptides are extremely promising molecules for the future development of drugs for use against breast cancer.

Synthetic Peptide Purification via Solid-Phase Extraction with Gradient Elution: A Simple, Economical, Fast, and Efficient Methodology.

A methodology was implemented for purifying peptides in one chromatographic run via solid-phase extraction (SPE), reverse phase mode (RP), and gradient elution, obtaining high-purity products with good yields. Crude peptides were analyzed by reverse phase high performance liquid chromatography and a new mathematical model based on its retention time was developed in order to predict the percentage of organic modifier in which the peptide will elute in RP-SPE. This information was used for designing the elution program of each molecule. It was possible to purify peptides with different physicochemical properties, showing that this method is versatile and requires low solvent consumption, making it the least polluting one. Reverse phase-SPE can easily be routinely implemented. It is an alternative to enrich and purified synthetic or natural molecules.

Contribution of basal and postprandial hyperglycaemia in type 2 diabetes patients treated by an intensified insulin regimen: Impact of pump therapy in the OPT2mise trial.

AIMS: The relative contribution of basal hyperglycaemia (BHG) and postprandial hyperglycaemia (PPHG) in type 2 diabetes patients treated with multiple daily injections (MDI) of insulin is poorly documented. In this study, the BHG and PPHG of patients from the OPT2mise study who were initially treated with MDI were assessed before randomization and again after 6 months of continuous subcutaneous insulin infusion (CSII). MATERIALS AND METHODS: Blinded continuous glucose monitoring (CGM) data were collected in 259 MDI patients after completion of an 8-week run-in period. The hyperglycaemic area under the curve (AUC) during the 24-hour basal period (AUC-B) and the postprandial period (AUC-P) were compared with analysis of variance based on contribution to total hyperglycaemia in HbA1c groups (Group 1, <8%; Group 2, 8%-8.4%; Group 3, 8.5%-8.9%; Group 4, 9%-9.4%; Group 5, ≥9.5%). Changes in AUC-B and AUC-P were assessed after 6 months of pump therapy in 131 randomized participants with available CGM recordings. RESULTS: In patients undergoing MDI therapy, AUC-B was 21.6% to 54.8% lower in Group 4 to 1 (P = .0138 and P = .0002, respectively) in comparison to Group 5. In contrast, AUC-P did not differ among HbA1c groups (P = .1009). HbA1c correlated with AUC-B, but not with AUC-P. After switching to CSII, AUC-B and AUC-P decreased by 21% and 17%, respectively. When comparing responders with non-responders to CSII therapy, no between-group differences were observed in AUC-B and AUC-P. CONCLUSIONS: Basal hyperglycaemia is the major determinant of overall exposure to hyperglycaemia in type 2 diabetes with MDI failure.

Factors associated with improved glycemic control following continuous subcutaneous insulin infusion therapy in patients with type 2 diabetes uncontrolled with bolus-basal insulin regimens: An analysis from the OpT2mise randomized trial.

This analysis investigated factors associated with the decrease in HbA1c in patients receiving continuous subcutaneous insulin infusion (CSII) in the OpT2mise randomized trial. In this study, patients with type 2 diabetes and HbA1c >8% following multiple daily injections (MDI) optimization were randomized to receive CSII (n = 168) or MDI (n = 163) for 6 months. Patient-related and treatment-related factors associated with decreased HbA1c in the CSII arm were identified by univariate and multivariate analyses. CSII produced a significantly greater reduction in HbA1c than MDI, and the treatment difference increased with baseline HbA1c. In the CSII arm, the only factors significantly associated with decreased HbA1c were higher baseline HbA1c (P < .001), geographical region (P < .001), higher educational level (P = .012), higher total cholesterol level (P = .002), lower variability of baseline glucose values on continuous glucose monitoring (P < .001) and the decrease in average fasting self-monitored blood glucose at 6 months (P < .001). These findings suggest that CSII offers an option to improve glycemic control in a broad range of patients with type 2 diabetes in whom control cannot be achieved with MDI. OpT2mise ClinicalTrials.gov number: NCT01182493 (https://clinicaltrials.gov/).

Antimicrobial Activity of Truncated and Polyvalent Peptides Derived from the FKCRRQWQWRMKKGLA Sequence against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923.

Peptides derived from LfcinB were designed and synthesized, and their antibacterial activity was tested against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923. Specifically, a peptide library was constructed by systemically removing the flanking residues (N or C-terminal) of Lfcin 17-31 (17FKCRRWQWRMKKLGA31), maintaining in all peptides the 20RRWQWR25 sequence that corresponds to the minimal antimicrobial motif. For this research, also included were (i) a peptide containing an Ala instead of Cys ([Ala19]-LfcinB 17-31) and (ii) polyvalent peptides containing the RRWQWR sequence and a non-natural amino acid (aminocaproic acid). We established that the lineal peptides LfcinB 17-25 and LfcinB 17-26 exhibited the greatest activity against E. coli ATCC 25922 and S. aureus ATCC 25923, respectively. On the other hand, polyvalent peptides, a dimer and a tetramer, exhibited the greatest antibacterial activity, indicating that multiple copies of the sequence increase the activity. Our results suggest that the dimeric and tetrameric sequence forms potentiate the antibacterial activity of lineal sequences that have exhibited moderate antibacterial activity.

Antibacterial Synthetic Peptides Derived from Bovine Lactoferricin Exhibit Cytotoxic Effect against MDA-MB-468 and MDA-MB-231 Breast Cancer Cell Lines.

Linear, dimeric, tetrameric, and cyclic peptides derived from lactoferricin B, containing the RRWQWR motif, were designed, synthesized, purified, and characterized using RP-HPLC chromatography and MALDI-TOF mass spectrometry. The antibacterial activity of the designed peptides against E. coli (ATCC 11775 and 25922) and their cytotoxic effect against MDA-MB-468 and MDA-MB-231 breast cancer cell lines were evaluated. Dimeric and tetrameric peptides showed higher antibacterial activity in both bacteria strains than linear peptides. The dimeric peptide (RRWQWR)2K-Ahx exhibited the highest antibacterial activity against the tested bacterial strains. Furthermore, the peptides with high antibacterial activity exhibited significant cytotoxic effect against the tested breast cancer cell lines. This cytotoxic effect was fast and dependent on the peptide concentration. The tetrameric molecule containing RRWQWR motif has an optimal cytotoxic effect at a concentration of 22 µM. The evaluated dimeric and tetrameric peptides could be considered as candidates for developing new therapeutic agents against breast cancer. Polyvalence of linear sequences could be considered as a novel and versatile strategy for obtaining molecules with high anticancer activity.

Design, Synthesis, and Use of Peptides Derived from Human Papillomavirus L1 Protein for the Modification of Gold Electrode Surfaces by Self-Assembled Monolayers.

In order to obtain gold electrode surfaces modified with Human Papillomavirus L1 protein (HPV L1)-derived peptides, two sequences, SPINNTKPHEAR and YIK, were chosen. Both have been recognized by means of sera from patients infected with HPV. The molecules, Fc-Ahx-SPINNTKPHEAR, Ac-C-Ahx-(Fc)KSPINNTKPHEAR, Ac-C-Ahx-SPINNTKPHEAR(Fc)K, C-Ahx-SPINNTKPHEAR, and (YIK)2-Ahx-C, were designed, synthesized, and characterized. Our results suggest that peptides derived from the SPINNTKPHEAR sequence, containing ferrocene and cysteine residues, are not stable and not adequate for electrode surface modification. The surface of polycrystalline gold electrodes was modified with the peptides C-Ahx-SPINNTKPHEAR or (YIK)2-Ahx-C through self-assembly. The modified polycrystalline gold electrodes were characterized via infrared spectroscopy and electrochemical measurements. The thermodynamic parameters, surface coverage factor, and medium pH effect were determined for these surfaces. The results indicate that surface modification depends on the peptide sequence (length, amino acid composition, polyvalence, etc.). The influence of antipeptide antibodies on the voltammetric response of the modified electrode was evaluated by comparing results obtained with pre-immune and post-immune serum samples.

Synthetic Peptides Derived from Bovine Lactoferricin Exhibit Antimicrobial Activity against E. coli ATCC 11775, S. maltophilia ATCC 13636 and S. enteritidis ATCC 13076.

Linear, dimeric, tetrameric, and cyclic peptides derived from lactoferricin B-containing non-natural amino acids and the RWQWR motif were synthesized, purified, and characterized using RP-HPLC, MALDI-TOF mass spectrometry, and circular dichroism. The antibacterial activity of peptides against Escherichia coli ATCC 11775, Stenotrophomonas maltophilia ATCC 13636, and Salmonella enteritidis ATCC 13076 was evaluated. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined. The synthetic bovine lactoferricin exhibited antibacterial activity against E. coli ATCC 11775 and S. enteritidis ATCC 13076. The dimeric peptide (RRWQWR)2K-Ahx exhibited the highest antibacterial activity against the tested bacterial strain. The monomeric, cyclic, tetrameric, and palindromic peptides containing the RWQWR motif exhibited high and specific activity against E. coli ATCC 11775. The results suggest that short peptides derived from lactoferricin B could be considered as potential candidates for the development of antibacterial agents against infections caused by E. coli.

Hypoxic pulmonary vasoconstriction, carotid body function and erythropoietin production in adult rats perinatally exposed to hyperoxia.

KEY POINTS: Adult animals that have been perinatally exposed to oxygen-rich atmospheres (hyperoxia), recalling those used for oxygen therapy in infants, exhibit a loss of hypoxic pulmonary vasoconstriction, whereas vasoconstriction elicited by depolarizing agents is maintained. Loss of pulmonary hypoxic vasoconstriction is not linked to alterations in oxygen-sensitive K(+) currents in pulmonary artery smooth muscle cells. Loss of hypoxic vasoconstriction is associated with early postnatal oxidative damage and corrected by an antioxidant diet. Perinatal hyperoxia damages carotid body chemoreceptor cell function and the antioxidant diet does not reverse it. The hypoxia-elicited increase in erythropoietin plasma levels is not affected by perinatal hyperoxia. The potential clinical significance of the findings in clinical situations such as pneumonia, chronic obstructive pulmonary disease or general anaesthesia is considered. ABSTRACT: Adult mammalians possess three cell systems that are activated by acute bodily hypoxia: pulmonary artery smooth muscle cells (PASMC), carotid body chemoreceptor cells (CBCC) and erythropoietin (EPO)-producing cells. In rats, chronic perinatal hyperoxia causes permanent carotid body (CB) atrophy and functional alterations of surviving CBCC. There are no studies on PASMC or EPO-producing cells. Our aim is to define possible long-lasting functional changes in PASMC or EPO-producing cells (measured as EPO plasma levels) and, further, to analyse CBCC functional alterations. We used 3- to 4-month-old rats born and reared in a normal atmosphere or exposed to perinatal hyperoxia (55-60% O2 for the last 5-6 days of pregnancy and 4 weeks after birth). Perinatal hyperoxia causes an almost complete loss of hypoxic pulmonary vasoconstriction (HPV), which was correlated with lung oxidative status in early postnatal life and prevented by antioxidant supplementation in the diet. O2 -sensitivity of K(+) currents in the PASMC of hyperoxic animals is normal, indicating that their inhibition is not sufficient to trigger HPV. Perinatal hyperoxia also abrogated responses elicited by hypoxia on catecholamine and cAMP metabolism in the CB. An increase in EPO plasma levels elicited by hypoxia was identical in hyperoxic and control animals, implying a normal functioning of EPO-producing cells. The loss of HPV observed in adult rats and caused by perinatal hyperoxia, comparable to oxygen therapy in premature infants, might represent a previously unrecognized complication of such a medical intervention capable of aggravating medical conditions such as regional pneumonias, atelectases or general anaesthesia in adult life.