Asymptomatic human carriers of Leishmania chagasi

In Brazil, programs based on elimination of infected dogs have not curtailed the spread of visceral leishmaniasis (VL), suggesting that other reservoirs of infection exist. Persons with active VL can infect the sand fly vector, but in endemic areas, persons with asymptomatic infections, whose infectivity to sand flies is unknown, are far more numerous. In this study, a polymerase chain reaction-based assay detected kinetoplast DNA of Leishmania chagasi in the blood of eight of 108 asymptomatic persons living with patients with recently diagnosed VL. These eight persons had low or unmeasurable levels of IgG antibodies to Leishmania, demonstrating the insensitivity of serology for subclinical infection. All eight persons had positive leishmanin skin test results, as did 70% of persons living in households of persons with active VL. Even if a small proportion of such asymptomatic persons are infective to sand flies, they represent a formidable reservoir of infection in endemic areas.     

The use of optical fiber in endodontic photodynamic therapy. Is it really relevant?

This study analyzed the necessity of use of an optical fiber/diffusor when performing antimicrobial photodynamic therapy (PDT) associated with endodontic therapy. Fifty freshly extracted human single-rooted teeth were used. Conventional endodontic treatment was performed using a sequence of ProTaper (Dentsply Maillefer Instruments), the teeth were sterilized, and the canals were contaminated with Enterococcus faecalis 3 days’ biofilm. The samples were divided into five groups: group 1—ten roots irradiated with a laser tip (area of 0.04 cm²), group 2—ten roots irradiated with a smaller laser tip (area of 0.028 cm²), and group 3—ten teeth with the crown, irradiate with the laser tip with 0.04 cm² of area. The forth group (G4) followed the same methodology as group 3, but the irradiation was performed with smaller tip (area of 0.028 cm²) and G5 ten teeth with crown were irradiated using a 200-mm-diameter fiber/diffusor coupled to diode laser. Microbiological samples were taken after accessing the canal, after endodontic therapy, and after PDT. Groups 1 and 2 showed a reduction of two logs (99%), groups 3 and 4 of one log (85% and 97%, respectively), and group 5 of four logs (99.99%). Results suggest that the use of PDT added to endodontic treatment in roots canals infected with E. faecalis with the optical fiber/diffusor is better than when the laser light is used directed at the access of cavity.     

The impact of introducing new vaccines on the health system: Case studies from six low- and middle-income countries

Objective

We aimed to explore the impacts of new vaccine introductions on immunization programmes and health systems in low- and middle-income countries.

Methods

We conducted case studies of seven vaccine introductions in six countries (Cameroon, PCV; Ethiopia, PCV; Guatemala, rotavirus; Kenya, PCV; Mali, Meningitis A; Mali, PCV; Rwanda, HPV). Interviews were conducted with 261 national, regional and district key informants and questionnaires were completed with staff from 196 health facilities. Routine data from districts and health facilities were gathered on vaccination and antenatal service use. Data collection and analysis were structured around the World Health Organisation health system building blocks.

Findings

The new vaccines were viewed positively and seemed to integrate well into existing health systems. The introductions were found to have had no impact on many elements within the building blocks framework. Despite many key informants and facility respondents perceiving that the new vaccine introductions had increased coverage of other vaccines, the routine data showed no change. Positive effects perceived included enhanced credibility of the immunisation programme and strengthened health workers’ skills through training. Negative effects reported included an increase in workload and stock outs of the new vaccine, which created a perception in the community that all vaccines were out of stock in a facility. Most effects were found within the vaccination programmes; very few were reported on the broader health systems. Effects were primarily reported to be temporary, around the time of introduction only.

Conclusion

Although the new vaccine introductions were viewed as intrinsically positive, on the whole there was no evidence that they had any major impact, positive or negative, on the broader health systems.     

Induction of a single dose of streptozotocin (50 mg) in rat model causes insulin resistance with type 2 diabetes mellitus

Streptozotocin (STZ) is a broad-spectrum antibiotic that is toxic to the insulin-producing beta cells of the pancreatic islets. STZ is currently used clinically for the treatment of metastatic islet cell carcinoma of the pancreas and the induction of diabetes mellitus (DM) in rodents. So far, there has been no previous research to show that STZ injection in rodents causes insulin resistance in type 2 diabetes mellitus (T2DM). The purpose of this study was to determine if rats (Sprague–Dawley) developed type 2 diabetes mellitus (insulin resistance) after 72 h of intraperitoneal administration of 50 mg/kg STZ. Rats with fasting blood glucose levels above 11.0 mM, 72 h post-STZ induction, were used. The body weight and plasma glucose levels were measured every week throughout the 60-day treatment period. The plasma, liver, kidney, pancreas, and smooth muscle cells were harvested for antioxidant, biochemical analysis, histology, and gene expression studies. The results revealed that STZ was able to destroy the pancreatic insulin-producing beta cell, as evidenced by an increase in plasma glucose level, insulin resistance, and oxidative stress. Biochemical investigation indicates that STZ can generate diabetes complications through hepatocellular damage, elevated HbA1c, kidney damage, hyperlipidemia, cardiovascular damage, and impairment of the insulin-signaling pathway.