Presence of bound substrate in lactate dehydrogenase from carp liver

While attempting to purify UDP-galactose 4-epimerase from carp liver extract at pH 8.0, it was observed that the preparation even after dialysis could reduce NAD to NADH, interfering epimerase assay. The NAD reduction activity and the epimerase were co-eluted in a series of chromatographic steps. Mass spectrometric analysis of semi-purified fraction revealed that carp liver lactate dehydrogenase (LDH) contained bound lactate which was converted to pyruvate in the presence of NAD. The enzyme-bound lactate and the association with epimerase stabilized LDH from trypsin digestion and thermal inactivation at 45 degrees C by factors of 2.7 and 4.2 respectively, as compared to substrate-free LDH. LDH and epimerase do not belong to any one pathway, but are the rate-limiting enzymes of two different pathways of carbohydrate metabolism. Typically, strongly associated enzymes work in combination, such as two enzymes of the same metabolic pathway. In that background, co-purification of LDH and epimerase as reloaded in this study was an unusual phenomenon.     

Blunted IL17/IL22 and Pro-Inflammatory Cytokine Responses in the Genital Tract and Blood of HIV-Exposed, Seronegative Female Sex Workers in Kenya

Background

Identifying the immune correlates of reduced susceptibility to HIV remains a key goal for the HIV vaccine field, and individuals who are HIV-exposed, seronegative (HESN) may offer important clues. Reduced systemic immune activation has been described in HESN individuals. Conversely, pro-inflammatory T cell subsets, particularly CD4+ T cells producing the cytokine IL17 (Th17 cells), may represent a highly susceptible target for HIV infection after sexual exposure. Therefore, we characterized the cellular pro-inflammatory and IL17/IL22 cytokine immune milieu in the genital mucosa and blood of HESN female sex workers (FSWs).

Methods and Results

Blinded lab personnel characterized basal and mitogen-induced gene and cytokine immune responses in the cervix and blood of HESN FSWs (n = 116) and non-FSW controls (n = 17) using qPCR and ELISA. IL17 and IL22 production was significantly reduced in both the cervix and blood of HESNs, both in resting cells and after mitogen stimulation. In addition, HESN participants demonstrated blunted production of both pro-inflammatory cytokines and β-chemokines.

Discussion and Conclusions

We conclude that HIV exposure without infection was associated with blunted IL17/IL22 and pro-inflammatory responses, both systemically and at the site of mucosal HIV exposure. It will be important for further studies to examine the causal nature of the association and to define the cell subsets responsible for these differences.     

The association between changes in height and obesity in Chilean preschool children: 1996-2004

Objectives: To establish the association between changes in height and prevalence of obesity between 1996 and 2004 in Chilean preschool children. Research Methods and Procedures: Children registered in the Junta Nacional de Jardines Infantiles (JUNJI) preschool program were routinely measured three times a year and in consecutive years. Two indices [weight‐for‐height z‐scores (WHZ) and BMI centiles] were used to define obesity. Height‐for‐age z‐scores (HAZ) were used to define stature. Generalized estimating equations were used to describe the relationship between stature and obesity while controlling for repeated measurements in children. Results: The prevalence of obesity in Chilean preschool children has remained relatively constant over the past 9 years when either index is used. The prevalence of stunted (HAZ ≤2) children has decreased, while the proportion of children who are tall (HAZ >2) has increased. Using WHZ to define obesity, stunted children do not seem to be at increased risk of obesity when compared with children of normal height. Tall children were strongly protected from obesity when either criterion was used to define obesity. Discussion: The lack of association between stunting and obesity using WHZ ≥2 likely reflects the fact that Chile is in the post‐transitional phase of the nutrition transition, and stunting is no longer a risk factor for obesity; however, the associations observed between stunting and BMI suggest that either WHZ or BMI, or both, are inaccurate criteria to define overweight. Conclusions: There is a unique relationship between stature and obesity in preschool children that is different from that observed in older children in the same population.     

Impact of IRS: Four-years of entomological surveillance of the Indian Visceral Leishmaniases elimination programme

BackgroundIn 2005, Bangladesh, India and Nepal agreed to eliminate visceral leishmaniasis (VL) as a public health problem. The approach to this was through improved case detection and treatment, and controlling transmission by the sand fly vector Phlebotomus argentipes, with indoor residual spraying (IRS) of insecticide. Initially, India applied DDT with stirrup pumps for IRS, however, this did not reduce transmission. After 2015 onwards, the pyrethroid alpha-cypermethrin was applied with compression pumps, and entomological surveillance was initiated in 2016.MethodsEight sentinel sites were established in the Indian states of Bihar, Jharkhand and West Bengal. IRS coverage was monitored by household survey, quality of insecticide application was measured by HPLC, presence and abundance of the VL vector was monitored by CDC light traps, insecticide resistance was measured with WHO diagnostic assays and case incidence was determined from the VL case register KAMIS.ResultsComplete treatment of houses with IRS increased across all sites from 57% in 2016 to 70% of houses in 2019, rising to >80% if partial house IRS coverage is included (except West Bengal). The quality of insecticide application has improved compared to previous studies, average doses of insecticide on filters papers ranged from 1.52 times the target dose of 25mg/m² alpha-cypermethrin in 2019 to 1.67 times in 2018. Resistance to DDT has continued to increase, but the vector was not resistant to carbamates, organophosphates or pyrethroids. The annual and seasonal abundance of P. argentipes declined between 2016 to 2019 with an overall infection rate of 0.03%. This was associated with a decline in VL incidence for the blocks represented by the sentinel sites from 1.16 per 10,000 population in 2016 to 0.51 per 10,000 in 2019.ConclusionThrough effective case detection and management reducing the infection reservoirs for P. argentipes in the human population combined with IRS keeping P. argentipes abundance and infectivity low has reduced VL transmission. This combination of effective case management and vector control has now brought India within reach of the VL elimination targets.     

Malaria exacerbates experimental mycobacterial infection in vitro and in vivo

Tuberculosis (Mtb) and malaria are among the most important infectious causes of morbidity and mortality worldwide, causing an estimated 1.5 million and 1 million deaths every year, respectively. Here we demonstrate a biological interaction between malaria and mycobacteria in vitro and in vivo. Murine macrophages co-incubated with Plasmodium falciparum parasitized erythrocytes demonstrated impaired control of intracellular Mtb replication, and reduced production of reactive nitrogen species in response to mycobacteria. Infection of C57BL/6 mice with Plasmodium species exacerbated the course of acute mycobacterial infection (57% increase in peak splenic CFU, p = 0.043 for difference over time course of infection), induced disruption of the structural integrity of established granulomas, and caused reactivation of latent mycobacterial infection (2.6-fold increase in peak splenic CFU, p = 0.016 for difference over time course of reactivation). Malaria pigment deposition within the granulomas of co-infected mice suggested that the influx of dysfunctional hemozoin-laden monocytes into the locus of mycobacterial control may contribute to impaired containment of mycobacteria. Collectively, these results point to malaria-induced dysregulation of innate and adaptive anti-mycobacterial defences, and suggest that the interaction of these globally important pathogens may potentiate Mtb infection and transmission.