Browse

You are looking at 1 - 10 of 83,873 items for

  • Refine by Access: All Content x
Clear All

Abstract

Steviol glycosides (SGs) are natural sweeteners derived from stevia leaves, which have various applications in food and beverage products. The extraction efficiency of SGs depends on several factors, such as solvent type, solid to solvent ratio, centrifugal force, and temperature. This study aimed to compare the effects of different solvents (ethanol and water) and leaf moisture (dry and fresh) on the extraction efficiency of major steviol glycosides (SGs) of rebaudioside A (Reb A), stevioside (ST), and rebaudioside C (Reb C) in stevia (var. Levent 93) plant. A Box–Behnken design was used to optimise the extraction parameters for each extraction type. The results showed that ethanol was a more effective solvent than water, however, aqueous extraction was more environmentally friendly and low-cost, and could also yield high concentrations of SGs when fresh leaves were used. The major SGs had similar concentrations in ethanolic extraction, but Reb A was twice as high as ST in aqueous extraction. Reb C was influenced by the solid to solvent ratio in both extraction types, but more so in water extraction. Temperature had a positive effect on ST and Reb C in water extraction of fresh leaves, but not in water extraction of dry leaves or ethanolic extraction. The results of this study contribute to the optimisation of SGs extraction from stevia leaves and provide insights for future research on the effects of different solvents and extraction parameters on the quality and purity of SGs.

Restricted access

Abstract

Klebsiella pneumoniae is one of the most prevalent bacteria causing urinary tract infections (UTIs). Its increasing resistance to a wide array of antibiotics limits available treatment options. This study investigated the characteristics and trends of antimicrobial resistance in K. pneumoniae isolated from UTIs in Crete, Greece, during 2017 and 2022. Among the 11,946 Enterobacteriaceae isolated from urine specimens, a total of 1,771 K. pneumoniae isolates were identified (14.8%), with an isolation frequency secondary to Escherichia coli (66.3%). K. pneumoniae isolates increased over the years, with a peak in the year 2022. Higher resistance rates were detected in ciprofloxacin (41%), trimethoprim/sulfamethoxazole (TMP/SMX) (38.1%) and nitrofurantoin (33.9%). Resistance to ciprofloxacin, amoxicillin/clavulanic acid, tigecycline, and TMP/SMX significantly increased from 33.7%, 24%, 6%, and 33.1%, respectively, over the years 2017–2019, to 47.8%, 34.2%, 14.3% and 42.8%, respectively, over the period 2020–2022. ESBL production and carbapenem resistance were decreased by 2.2% and 3.7%, respectively, over the two three-year periods (2017–2019 and 2020–2022). Among the 278 carbapenem-resistant K. pneumoniae (CRKP) isolates, 164 (59%), 66 (23.7%), 18 (6.5%) and 16 (5.8%) were positive for KPC, NDM, VIM and OXA-48 enzymes, respectively. Only 14 (5%) isolates harboured two carbapenemase genes, namely 10 (3.6%) both bla NDM and bla VIM, and 4 (1.4%) both bla KPC and bla NDM. Females, inpatients and the elderly were more frequently affected by CRKP. The frequency of multidrug-resistant (MDR) and extensively drug-resistant (XDR) isolates were 32.6% and 7.7%, respectively. Continuous surveillance of local microbial prevalence and monitoring of antimicrobial resistance patterns provide critical information to guide the empiric therapy for UTIs and control the spread of MDR bacteria.

Restricted access

Abstract

Both onion and shallot are the most common ingredients to use for many recipes. Consuming onion and shallot provide health benefits including antidiabetic effects. However, the benefits of onion and shallot mixture at different ratios have not been studied in terms of total phenolic content, total antioxidant capacity, superoxide dismutase (SOD)-like activity, and antidiabetic effects. Our study revealed that shallot significantly increased total phenolic content in the mixture from 492 ± 32 μg mL−1 (100% v/v onion) to 803 ± 24 μg mL−1 (100% v/v shallot) depending on the ratios of shallot in the mixture. Shallot also significantly enhanced total antioxidant capacity, SOD-like activity, α-amylase inhibition, and α-glucosidase inhibition in the mixture. Shallot juice exhibited the highest percentage inhibition of α-amylase activity (40.51 ± 1.57%) and α-glucosidase activity (89.61 ± 2.85%) in comparison to those of onion juice and the mixture. In addition, significant positive correlation between phenolic compound and different variables was observed (P < 0.05). Phenolic compounds present in onion and shallot are probably responsible for many health benefits including antidiabetic effects.

Restricted access

Abstract

A new species of the cleptoparasitic bee genus Tetralonioidella Strand, 1914, collected from Meghalaya, India is described. Only two species occur in India, namely Tetralonioidella himalayana (Bingham, 1897) and Tetralonioidella tricolor (Lieftinck, 1972). The new species, Tetralonioidella meghalayensis Dohling & Dey sp. n., is the third species of Tetralonioidella Strand, 1914 discovered in India. An updated checklist of species along with identification keys to female species of the genus Tetralonioidella from India are given. Illustrations of the female specimens studied are also provided.

Open access

Abstract

A simple, fast and selective analytical method has been developed for the simultaneous determination of allantoin and D-panthenol in cosmetic products containing Aloe vera extracts. The proposed method depends on reversed-phase liquid chromatography with isocratic flow profile of the mobile phase composed of acetonitrile–10 mM phosphoric acid (pH 2.5) (85:15, v/v), with a C18 column at 30 °C. The analytes were detected with UV–vis. detector at 210 nm. The injection volume was 20 μL. The linearity ranges were found to be 0.2–20 and 0.1–10 μg mL−1 for allantoin and D-panthenol, respectively. LOD values were found to be 0.07 μg mL−1 and 0.03 μg mL−1, LOQ values were found to be 0.2 and 0.1 μg mL−1 for allantoin and D-panthenol, respectively. No interference was observed from concomitants. The developed method was applied to the analysis of 10 different type cosmetic products. It is foreseen that the method will be able to be used in order to carry out routine analysis, quality control and standardization in cosmetic products containing allantoin and D-panthenol.

Open access
Acta Microbiologica et Immunologica Hungarica
Authors:
Sarra Dhraief
,
Khaoula Meftah
,
Samar Mhimdi
,
Houyem Khiari
,
Firas Aloui
,
Aida Borgi
,
Sondes Haddad-Boubaker
,
Amani Brik
,
Khaled Menif
,
Amel Kechrid
,
Aida Bouafsoun
, and
Hanen Smaoui

Abstract

The worldwide burden of disease of bacterial meningitis remains high, despite the decreasing incidence following introduction of routine vaccination campaigns.

The aim of our study was to evaluate the epidemiological and bacteriological profile of paediatric bacterial meningitis (BM) in Tunisian children, during the period 2003–2019, following the implementation of Haemophilus influenzae type b (Hib) vaccine (April 2011) and before 10-valent pneumoccocal conjugate vaccine (PCV10) introduction to the childhood immunization program.

All bacteriologically confirmed cases of BM admitted to children's hospital of Tunis were recorded (January 2003 to April 2019). Serogroups of Neisseria meningitidis (Nm) and serotypes of Streptococcus pneumoniae (Sp) and H. influenzae (Hi) and antibiotic resistance were determined using conventional and molecular methods.

Among 388 cases, the most frequent species were Sp (51.3%), followed by Nm (27.5%) and Hi (16.8%). We observed a significant decrease in Hi BM rate during the conjugated Hib vaccine use period (P < 0.0001). The main pneumococcal serotypes were 14, 19F, 6B, 23F and 19A and the serotype coverage of PCV10, PCV13, PCV15 and PCV20 was 71.3 and 78.8%, 79.4 and 81.9% respectively. The most frequent Nm serogroup was B (83.1%). Most Hi strains were of serotype b (86.9%). High levels of resistance were found: Sp and Nm to penicillin (respectively 60.1 and 80%) and Hi to ampicillin (42.6%). All meningococcal and Hi isolates were susceptible to third-generation cephalosporins and 7.2% of pneumococcal strains had decreased susceptibility to these antibiotics.

The Hib conjugate vaccine decreased the rate of BM. Sp dominated the aetiology of BM in children in Tunisia. Conjugate vaccines introducing decreases not only BM cases but also antimicrobial resistance.

Restricted access

Abstract

This paper analyses linking vowels of Hungarian in a paradigm-based approach. We argue that the quality of linking vowels is determined by such a complex interaction of phonological, morphological, and morphophonological factors on both stems and suffixes that attributing them to individual morphemes is not plausible. Instead in the model proposed here linking vowels emerge from the identification of initial and final substrings within and across paradigms.

Open access

Abstract

This study investigated the production of Mandarin and Fuzhou lexical tones by Mandarin-Fuzhou bilingual children. Forty children aged 6;11 to 7;6 and two groups of adults (Mandarin speakers and Fuzhou speakers) were asked to produce pre-selected familiar monosyllabic words. Adult judges' perceptual judgments and acoustic analysis showed that: (1) overall, these children's production performance of Mandarin tones was similar to adults', with very high accuracy; (2) children did not reach adult-like production competence in Fuzhou tones by age 7;6; and (3) there was an imbalance in children's development of the seven lexical tones in Fuzhou. Children's late and unbalanced development of Fuzhou tones could be ascribed to their unbalanced Mandarin-Fuzhou exposure, and it is argued that children might transfer the characteristics of the Mandarin tonal system to their production of Fuzhou tones.

Restricted access