NAD+-induced inhibition of phosphate transport in canine renal brush-border membranes Mediation through a process other than or in addition to NAD+ hydrolysis

We previously demonstrated inhibition of Na⁺-dependent ³²P_i transport in canine renal brush-border membranes in association with NAD⁺-induced ADP ribosylation of membrane protein(s) and postulated that NAD⁺ inhibits P_i transport across the brush-border membrane via ADP ribosylation. Recently it was shown that incubation of rat brush-border membrane with NAD⁺ resulted in release of P_i which was prevented by EDTA. It was proposed that NAD⁺-mediated inhibition of ³²P_i transport might occur through this mechanism. To determine whether NAD⁺ inhibited ³²P_i transport by a mechanism other than or in addition to release of P_i, we compared Na⁺-dependent ³²P_i counterflow in brush-border membrane equilibrated with P_i or with P_i generated from NAD⁺. Release of P_i from NAD⁺ incubated with brush-border membrane was confirmed. The increased uptake of ³²P_i which was demonstrated in brush-border membrane equilibrated with P_i was not measured when intravesicular P_i was generated from a concentration of NAD⁺ which effected ADP-ribosylation of brush border membranes (100 μM NAD⁺). In contrast, increased uptake of ³²P_i was demonstrated when intravesicular P_i was generated from 1 μM NAD⁺ which did not effect ADP ribosylation. Mg²⁺-dependent ADP ribosylation of brush-border membrane incubated with NAD⁺ was demonstrated which persisted during the time interval of ³²P_i uptake measurements. Our findings are compatible with the hypothesis that NAD⁺-induced ADP ribosylation of brush-border membrane protein(s) results in inhibition of P_i transport across the membrane in vivo. EDTA may act to prevent this inhibition in brush-border membrane by chelation of Mg²⁺ and decreased ADP ribosylation.     

Partial restoration of impaired alpha1-adrenergic responsiveness in parotid cells of aged rats by S-adenosylmethionine treatment

The age related decrease in alpha₁-adrenergic stimulated inositol 1,4,5 trisphosphate (IP₃) production in parotid cells of aged rats can be partially restored by treatment with S-adenosylmethionine (SAM). This effect is completely blocked by S-adenosyl homocysteine (SAH) and occurs in association with an increase in the conversion of phosphatidylethanolamine to phosphatidylcholine and a decrease in membrane viscosity. In contrast, SAM treatment actually inhibits stimulated IP₃ production in cells of young rats. The membrane viscosity of these cells is lower than that of those from aged rats. Although conversion of phosphatidylethanolamine to phosphatidylcholine is enhanced, no further decrease in membrane viscosity is elicited in young cell preparations. These findings suggest that age changes in the membrane environment may result in impaired alpha₁-adrenergic signal transduction and that such alterations may be at least partially reversible by SAM treatment.     

Biosynthesis of chondroitin sulfate: Microsomal proteoglycans

A microsomal preparation from chick embryo epiphyseal cartilage was incubated with UDP-[¹⁴C]glucuronic acid and UDP-N-acetylgalactosamine to form [¹⁴C] chondroitin-labeled proteoglycan. Two [¹⁴C]proteoglycan populations were obtained which differed in size, [¹⁴C]glycosaminoglycan content, and susceptibility to alkali. One population of [¹⁴C]proteoglycan appeared near the void volume on Sepharose 2B, while the other population was smaller, similar in size to monomer proteoglycan. The larger [¹⁴C]proteoglycan contained long [¹⁴C]chondroitin chains added to short primers; these chains were in part resistant to alkali cleavage from protein. The smaller [¹⁴C]proteoglycan contained mainly [¹⁴C]chondroitin chains of intermediate length added to endogenous chondroitin sulfate; these chains were all susceptible to alkali cleavage from protein. The larger [¹⁴C]proteoglycan may represent a precursor proteoglycan present at the site of glycosaminoglycan chain synthesis.     

Transient laminin beta 1a Induction Defines the Wound Epidermis during Zebrafish Fin Regeneration

The first critical stage in salamander or teleost appendage regeneration is creation of a specialized epidermis that instructs growth from underlying stump tissue. Here, we performed a forward genetic screen for mutations that impair this process in amputated zebrafish fins. Positional cloning and complementation assays identified a temperature-sensitive allele of the ECM component laminin beta 1a (lamb1a) that blocks fin regeneration. lamb1a, but not its paralog lamb1b, is sharply induced in a subset of epithelial cells after fin amputation, where it is required to establish and maintain a polarized basal epithelial cell layer. These events facilitate expression of the morphogenetic factors shha and lef1, basolateral positioning of phosphorylated Igf1r, patterning of new osteoblasts, and regeneration of bone. By contrast, lamb1a function is dispensable for juvenile body growth, homeostatic adult tissue maintenance, repair of split fins, or renewal of genetically ablated osteoblasts. fgf20a mutations or transgenic Fgf receptor inhibition disrupt lamb1a expression, linking a central growth factor to epithelial maturation during regeneration. Our findings reveal transient induction of lamb1a in epithelial cells as a key, growth factor-guided step in formation of a signaling-competent regeneration epidermis.     

Selenomethionine protects against adverse biological effects induced by space radiation

Ionizing radiation-induced adverse biological effects impose serious challenges to astronauts during extended space travel. Of particular concern is the radiation from highly energetic, heavy, charged particles known as HZE particles. The objective of the present study was to characterize HZE particle radiation-induced adverse biological effects and evaluate the effect of D-selenomethionine (SeM) on the HZE particle radiation-induced adverse biological effects. The results showed that HZE particle radiation can increase oxidative stress, cytotoxicity, and cell transformation in vitro, and decrease the total antioxidant status in irradiated Sprague-Dawley rats. These adverse biological effects were all preventable by treatment with SeM, suggesting that SeM is potentially useful as a countermeasure against space radiation-induced adverse effects. Treatment with SeM was shown to enhance ATR and CHK2 gene expression in cultured human thyroid epithelial cells. As ionizing radiation is known to result in DNA damage and both ATR and CHK2 gene products are involved in DNA damage, it is possible that SeM may prevent HZE particle radiation-induced adverse biological effects by enhancing the DNA repair machinery in irradiated cells.     

Community-level trachoma ecological associations and the use of geospatial analysis methods: A systematic review

BackgroundTrachoma is targeted for global elimination as a public health problem by 2030. Understanding individual, household, or community-associated factors that may lead to continued transmission or risk of recrudescence in areas where elimination has previously been achieved, is essential in reaching and maintaining trachoma elimination. We aimed to identify climatic, demographic, environmental, infrastructural, and socioeconomic factors associated in the literature with trachoma at community-level and assess the strength of their association with trachoma. Because of the potential power of geospatial analysis to delineate the variables most strongly associated with differences in trachoma prevalence, we then looked in detail at geospatial analysis methods used in previous trachoma studies.MethodsWe conducted a systematic literature review using five databases: Medline, Embase, Global Health, Dissertations & Theses Global, and Web of Science, including publications from January 1950 to January 2021. The review protocol was prospectively registered with PROSPERO (CRD42020191718).ResultsOf 35 eligible studies, 29 included 59 different trachoma-associated factors, with eight studies also including spatial analysis methods. Six studies included spatial analysis methods only. Higher trachomatous inflammation—follicular (TF) prevalence was associated with areas that: had lower mean annual precipitation, lower mean annual temperatures, and lower altitudes; were rural, were less accessible, had fewer medical services, had fewer schools; and had lower access to water and sanitation. Higher trachomatous trichiasis (TT) prevalence was associated with higher aridity index and increased distance to stable nightlights. Of the 14 studies that included spatial methods, 11 used exploratory spatial data analysis methods, three used interpolation methods, and seven used spatial modelling methods.ConclusionResearchers and decision-makers should consider the inclusion and potential influence of trachoma-associated factors as part of both research activities and programmatic priorities. The use of geospatial methods in trachoma studies remains limited but offers the potential to define disease hotspots and areas of potential recrudescence to inform local, national, and global programmatic needs.     

Association of exposure to polycyclic aromatic hydrocarbons with inflammation,oxidative DNA damage and renal-pulmonary dysfunctions in barbecue makers in Southern Nigeria

Background:Multiple organ dysfunctions have been linked to exposure to polycyclic aromatic hydrocarbons (PAH) and oxidative stress (OS), oxidative DNA damage, and inflammatory response to PAH have been implicated. The biomarkers of OS (malondialdehyde (MDA), total plasma peroxide (TPP), total antioxidant capacity (TAC), glutathione (GSH), nitric oxide (NO), oxidative stress index (OSI)); 8-hydroxy-2-deoxyguanosine (8-OHdG)); tumor necrosis factor-alpha (TNF-α)); 1-hydroxy pyrene (1-HOP)), serum and urine creatinine, uric acid (UA), estimated glomerular filtration rate (eGFR) and peak expiratory flow rate (PEFR) were assessed in barbecue makers. Methods:One hundred barbecue makers and 50 controls were enrolled into the study. Serum and urine creatinine, UA, TAC, MDA, GSH, NO and TPP were estimated by colorimetry, 8-OHdG and TNF-α by ELISA, PEFR using peak flow meter, 1-HOP by HPLC, eGFR and OSI by calculation. Results:Barbecue makers had lower TAC, PEFR, and higher TNF-α and OS compared to controls (p<0.05). Higher TNF-α, lipid peroxidation, and lower antioxidants were observed in barbecue makers who had worked for >5years compared to <5years (p <0.05). Increasing number of working hours was associated with higher NO, lipid peroxidation, OS and lower antioxidants in barbecue makers (p <0.05). Positive associations were observed between 1-HOP and TPP (r=0.570, p=0.000), OSI (r=0.299, p=0.035) and negative association between TAC and TNF-α (r=-0.209, p=0.037), MDA (r=-0.265, p=0.008) in barbecue makers. Conclusion:Increased lipid peroxidation, OS, inflammation and depressed antioxidants and lung function observed in barbecue makers suggest increased risk of chronic lung conditions which may be associated with exposure to PAH in barbecue fumes.Key Words: Inflammation, Kidney, Lipid Peroxidation, Lung, Oxidative Stress, Polycyclic Aromatic Hydrocarbon     

MORPHOLOGY AND FUNCTION OF CELLS OF HUMAN EMBRYONIC LIVER IN MONOLAYER CULTURE

A system for culturing human fetal liver cells in monolayers is described and the effects of various conditions of growth on the morphology and function of the cultured cells are presented. The addition of 10% calf serum or 1% human serum to the growth medium accelerated the proliferation of the liver cells, with subsequent loss of characteristic morphology and specific functional activity. In the absence of serum, the cultured liver cells retained their morphology and their function for at least 4 wk, as evidenced by secretion of serum albumin and storage of glycogen and iron.