Interplay of clinical biomarkers in allergic asthma diagnosis and severity: A case-control study.

Given asthma's large phenotypic diversity, the study was aimed to use specific biomarkers to characterize Allergic asthma (AA) and its severity. Blood was collected from 42 healthy controls (HCs) and 96 patients with AA. Biomarkers related to blood cell number and function: total leukocyte count (TLCs), neutrophil, lymphocyte, monocyte, eosinophil, basophil, neutrophil-to-lymphocyte ratio (NLR), immunoglobulin E (IgE), tryptase and eosinophilic cationic protein (ECP) as well as remodelling biomarkers (Matrix metalloproteinase (MMP-9), (MMP-16), Fibroblast growth factor (FGF-18) and (FGF-23) and alpha-skeletal muscle actin-1 (ACTa-1) were measured. Significant differences were observed in hematological parameters with higher levels of total leukocytes, eosinophil, and basophil counts in the AA group compared to HCs. The disease group also had significantly higher levels of several serum biomarkers (IgE, TPs, ECP, MMP-9, MMP-16, FGF-18, FGF-23, and ACTa-1) compared to HC. Forced expiratory volume 1 (FEV1) and forced vital capacity (FVC) had a strong negative correlation with ECP, IgE, and ACTa-1. FEV1 was negatively correlated with MMP-16 and tryptase. Patients with AA have higher levels of several biomarkers, such as MMP-9, MMP-16, FGF-18, FGF-23, IgE, tryptase, and ACTa-1. In addition, IgE, tryptase, ACTa-1, and MMP-16 are related to lung function impairment in AA. This indicates that measuring multiple biomarkers may be of value in the future when diagnosing and monitoring AA.

Scaling-up the use of sulfadoxine-pyrimethamine for the preventive treatment of malaria in pregnancy: results and lessons on scalability, costs and programme impact from three local government areas in Sokoto State, Nigeria.

BACKGROUND: Intermittent preventive treatment of malaria in pregnancy with 3+ doses of sulfadoxine-pyrimethamine (IPTp-SP) reduces maternal mortality and stillbirths in malaria endemic areas. Between December 2014 and December 2015, a project to scale up IPTp-SP to all pregnant women was implemented in three local government areas (LGA) of Sokoto State, Nigeria. The intervention included community education and mobilization, household distribution of SP, and community health information systems that reminded mothers of upcoming SP doses. Health facility IPTp-SP distribution continued in three intervention (population 661,606) and one counterfactual (population 167,971) LGAs. During the project lifespan, 31,493 pregnant women were eligible for at least one dose of IPTp-SP. METHODS: Community and facility data on IPTp-SP distribution were collected in all four LGAs. Data from a subset of 9427 pregnant women, who were followed through 42 days postpartum, were analysed to assess associations between SP dosages and newborn status. Nominal cost and expense data in 2015 Nigerian Naira were obtained from expenditure records on the distribution of SP. RESULTS: Eighty-two percent (n = 25,841) of eligible women received one or more doses of IPTp-SP. The SP1 coverage was 95% in the intervention LGAs; 26% in the counterfactual. Measurable SP3+ coverage was 45% in the intervention and 0% in the counterfactual LGAs. The mean number of SP doses in the intervention LGAs was 2.1; 0.4 in the counterfactual. Increased doses of IPTp-SP were associated with linear increases in newborn head circumference and lower odds of stillbirth. Any antenatal care utilization predicted larger newborn head circumference and lower odds of stillbirth. The cost of delivering three doses of SP, inclusive of the cost of medicines, was US$0.93-$1.20. CONCLUSIONS: It is feasible, safe, and affordable to scale up the delivery of high impact IPTp-SP interventions in low resource malaria endemic settings, where few women access facility-based maternal health services. ClinicalTrials.gov Identifier NCT02758353. Registered 29 April 2016, retrospectively registered.

Patterns and predictors of malaria care-seeking, diagnostic testing, and artemisinin-based combination therapy for children under five with fever in Northern Nigeria: a cross-sectional study.

BACKGROUND: Despite recent improvements in malaria prevention strategies, malaria case management remains a weakness in Northern Nigeria, which is underserved and suffers the country's highest rates of under-five child mortality. Understanding malaria care-seeking patterns and comparing case management outcomes to World Health Organization (WHO) and Nigeria's National Malaria Control Programme (NMCP) guidelines are necessary to identify where policy and programmatic strategies should focus to prevent malaria mortality and morbidity. METHODS: A cross-sectional survey based on lot quality assurance sampling was used to collect data on malaria care-seeking for children under five with fever in the last two weeks throughout Sokoto and Bauchi States. The survey assessed if the child received NMCP/WHO recommended case management: prompt treatment, a diagnostic blood test, and artemisinin-based combination therapy (ACT). Deviations from this pathway and location of treatment were also assessed. Lastly, logistic regression was used to assess predictors of seeking treatment. RESULTS: Overall, 76.7% of children were brought to treatment-45.5% to a patent medicine vendor and 43.8% to a health facility. Of children brought to treatment, 61.5% sought treatment promptly, but only 9.8% received a diagnostic blood test and 7.2% received a prompt ACT. When assessing adherence to the complete case management pathway, only 1.0% of children received NMCP/WHO recommended treatment. When compared to other treatment locations, health facilities provided the greatest proportion of children with NMCP/WHO recommended treatment. Lastly, children 7-59 months old were at 1.74 (p = 0.003) greater odds of receiving treatment than children ≤6 months. CONCLUSIONS: Northern Nigeria's coverage rates of NMCP/WHO standard malaria case management for children under five with fever fall short of the NMCP goal of 80% coverage by 2010 and universal coverage thereafter. Given the ability to treat a child with malaria differs greatly between treatment locations, policy and logistics planning should address the shortages of essential malaria supplies in recommended and frequently accessed treatment locations. Particular emphasis should be placed on integrating the private sector into standardized care and educating caregivers on the necessity for testing before treatment and the availability of free ACT in public health facilities for uncomplicated malaria.

Advances in biodistribution of gold nanoparticles: the influence of size, surface charge, and route of administration.

To improve the translational and clinical applications of gold nanoparticles (GNPs) in medicine there is a need for better understanding of physicochemical properties of the nanoparticles in relation to the systemic parameters andin-vivoperformance. This review presents the influence of physicochemical properties (surface charges and size) and route of administration on the biodistribution of GNPs. The role of protein corona (PC) (a unique biological identifier) as a barrier to biodistribution of GNPs, and the advances in engineered GNPs towards improving biodistribution are presented. Proteins can easily adsorb on charged (anionic and cationic) functionalized GNPs in circulation and shape the dynamics of their biodistribution. Non-ionic coatings such as PEG experience accelerated blood clearance (ABC) due to immunogenic response. While zwitterionic coatings provide stealth effects to formation of PC on the GNPs. GNPs with sizes less than 50 nm were found to circulate to several organs while the route of administration of the GNPs determines the serum protein that adsorbs on the nanoparticles.

Traditional uvulectomy; practice and belief among Sudanese children in Khartoum hospitals: A multi-center cross-sectional study.

BACKGROUND: Traditional healing practices are common in Sub-Saharan Africa. Traditional uvulectomy (TU) is the removal of the uvula with a sharp curved knife and is often practised in children under five years old. This practice is believed to have a therapeutic effect on children suffering from sore throat, vomiting or difficulty breastfeeding. OBJECTIVES: This study aimed to describe the practice of traditional uvulectomy and Sudanese mothers' perception of it. METHODS: A cross-sectional study was conducted in seven teaching hospitals across Khartoum State. We interviewed 385 mothers of children who presented to pediatric units using a semi-structured questionnaire. The study period spanned from July 2022-February 2023. RESULTS: A total of 385 mothers of children under five participated in this study. 33 % of mothers believed in the practice of traditional uvulectomy, yet only 17.9 % of children under five years had undergone TU. Reasons for performing TU included persistent cough (36.9 %), vomiting (33 %), difficulty in breastfeeding (22.6 %) and TU being a family tradition (25.7 %). Factors significantly associated with these practices were the mother's age, her level of education and the family's regional origin. Mothers reported that no major complications to the children were perceived as a result of the TU procedure. CONCLUSION: The practice of TU is prevalent among children who present to hospitals seeking medical advice. More than one-third of mothers had misconceptions regarding the uvula. Health education campaigns targeting females of childbearing age, and health practitioners at primary health centres and hospitals must raise awareness related to this practice.

In Vivo Anti-Hepatocellular Carcinoma Effects of the Chloroform Root Extract of Clausena excavata Burm.

Liver cancer is the most common cancer among males in Africa. The disease has a poor prognosis and its treatment is associated with toxicity and resistance. For this reason, numerous herbal combinations are being subjected to anticancer screening to circumvent the shortcomings of the conventional anticancer drugs. In the current study, the in vivo anti-cancer effects of the chloroform root extract of the herb, Clausena excavata Burm were investigated. Liver cancer was induced in mice by a single intraperitoneal injection of diethylnitrosamine (DEN) followed by oral administration of the promoter of carcinogenesis, 2-aminoacetyl fluorine that was mixed with the mice feed. The cytotoxicity of the root extract of C. excavata on liver cancer cells was investigated using liver enzyme, histology, DNA fragmentation and caspases assays. Real time qPCR was conducted to evaluate the effect of the extract on apoptotic genes. The findings revealed that the extract of C. excavata significantly decreased the progression of hepatocarcinogenesis and the toxicity-induced production of the liver enzymes, alanine and aspartate aminotransferases. The histological analyses of the liver tissues revealed evidence of apoptotic cell death. The extract also provoked significant (p < .05) expressions of caspase 9 protein and gene as well as other apoptotic genes (P53, P27, Apaf-1, cytochrome C, bax and bid). Therefore, we postulate that the chloroform root extract of C. excavata induces apoptosis of liver cancer in mice.

Establishment of New Immunostatistical Equations for Diagnosis and Follow-Up of Gluten-Free Diet in Patients with Celiac Disease.

<b>Background and Objective:</b> Celiac disease (CD) is an autoimmune condition characterized by immune responses to gluten. The reported prevalence of CD has increased globally due to improved screening and diagnostic techniques, however, there is significant global variation in methods of diagnosis and follow-up. A new immunostatistical equation that determines the values of two types of antibodies using the total IgA test. <b>Materials and Methods:</b> Only 70 blood samples were taken from people who had celiac disease or were suspected of having it, with ages ranging from 5 to 40 years and they were separated into two groups. The first group contained 40 people of both sexes who had previously been diagnosed with celiac disease, while the second group included 30 individuals of both sexes, with ages ranging from 5 to 35 years, who were suspected of having celiac disease due to the appearance of some clinical symptoms. The control group also included 30 blood samples from healthy individuals of both sexes, with ages ranging from 5 to 40 years. Total IgA antibody tTG/IgA and DGP/IgA levels were estimated for all study samples. <b>Results:</b> By using a regression coefficient test the results showed the percentage of the effect of total IgA on tTG/IgA, DGP/IgA amounted to 11 and 25%, respectively, as shown by the value of the coefficient of clarifications (R²) in patients with CD. On the other hand, The percentage of the effect of total IgA on tTG/IgA and DGP/IgA amounted to 11, 14%, respectively, as shown by the value of the coefficient of clarifications (R²) in patients with suspected CD in p<u><</u>0.05. The results of the study were revealed and through the regression coefficient, four new immunostatistical equations were mathematically derived that give the value of tTG/IgA and DGP/IgA based solely on the total IgA test in the laboratory. <b>Conclusion:</b> By adopting one laboratory test which determines total IgA, the study concluded four new immunostatistical equations that will help academic researchers and attending physicians to diagnose celiac disease in addition to following up on patient's adherence to a gluten-free diet.

Mechanisms of cancer cell death induction by triptolide.

Drug resistance is a hot topic issue in cancer research and therapy. Although cancer therapy including radiotherapy and anti-cancer drugs can kill malignant cells within the tumor, cancer cells can develop a wide range of mechanisms to resist the toxic effects of anti-cancer agents. Cancer cells may provide some mechanisms to resist oxidative stress and escape from apoptosis and attack by the immune system. Furthermore, cancer cells may resist senescence, pyroptosis, ferroptosis, necroptosis, and autophagic cell death by modulating several critical genes. The development of these mechanisms leads to resistance to anti-cancer drugs and also radiotherapy. Resistance to therapy can increase mortality and reduce survival following cancer therapy. Thus, overcoming mechanisms of resistance to cell death in malignant cells can facilitate tumor elimination and increase the efficiency of anti-cancer therapy. Natural-derived molecules are intriguing agents that may be suggested to be used as an adjuvant in combination with other anticancer drugs or radiotherapy to sensitize cancer cells to therapy with at least side effects. This paper aims to review the potential of triptolide for inducing various types of cell death in cancer cells. We review the induction or resistance to different cell death mechanisms such as apoptosis, autophagic cell death, senescence, pyroptosis, ferroptosis, and necrosis following the administration of triptolide. We also review the safety and future perspectives for triptolide and its derivatives in experimental and human studies. The anticancer potential of triptolide and its derivatives may make them effective adjuvants for enhancing tumor suppression in combination with anticancer therapy.

An unbiased and efficient assessment of excitability of sensory neurons for analgesic drug discovery.

Alleviating chronic pain is challenging, due to lack of drugs that effectively inhibit nociceptors without off-target effects on motor or central neurons. Dorsal root ganglia (DRG) contain nociceptive and non-nociceptive neurons. Drug screening on cultured DRG neurons, rather than cell lines, allows for the identification of drugs most potent on nociceptors with no effects on non-nociceptors (as a proxy for unwanted side effects on central nervous system and motor neurons). However, screening using DRG neurons is currently a low-throughput process, and there is a need for assays to speed this process for analgesic drug discovery. We previously showed that veratridine elicits distinct response profiles in sensory neurons. Here, we show evidence that a veratridine-based calcium assay allows for an unbiased and efficient assessment of a drug effect on nociceptors (targeted neurons) and non-nociceptors (nontargeted neurons). We confirmed the link between the oscillatory profile and nociceptors, and the slow-decay profile and non-nociceptors using 3 transgenic mouse lines of known pain phenotypes. We used the assay to show that blockers for Nav1.7 and Nav1.8 channels, which are validated targets for analgesics, affect non-nociceptors at concentrations needed to effectively inhibit nociceptors. However, a combination of low doses of both blockers had an additive effect on nociceptors without a significant effect on non-nociceptors, indicating that the assay can also be used to screen for combinations of existing or novel drugs for the greatest selective inhibition of nociceptors.

The Trauma and Suicide Potential Index-5: Psychometric Evaluation in College Samples.

We provide a brief description of the development of the Trauma and Suicide Potential Index-5 (TSPI-5) and report on the psychometric properties of scores from the new instrument. The TSPI-5 is designed to assess an individual's desire to attempt suicide due to experiencing a trauma. We examined the structure of the instrument in two independent undergraduate samples. Study 1 (N = 415) examined the structure of the TSPI-5 using exploratory structural equation modeling. Study 2 (N = 538) reexamined the instrument structure using the same modeling strategy and also examined other validity estimates. Study 1 demonstrated an adequate fit to the sample data (χ2 [1, N = 415] = 215.99, p < .001, comparative fit index (CFI ) = .969, Tucker-Lewis non-normed fit index (TLI) = .939, root mean squared error of approximation (RMSEA) = .319 [90% confidence interval (CI) = .283, .356], p < .001) and suggested evidence for unidimensionality. Study 2 confirmed the unidimensionality of the TSPI-5 as shown by acceptable fit estimates to the sample data, χ2 (5, N = 538) = 80.45, p < .001, CFI = .996, TLI = .99, RMSEA = .17 (90% CI = .140, .200), p < .001. Scale reliability estimates for the TSPI-5 were good in Study 1 (omega = .94) and Study 2 (omega = .96). The TSPI-5 is a brief unidimensional instrument and its scores demonstrated good reliability and validity for assessing suicide-related behaviors due to experiencing a trauma in undergraduate samples.

In Silico Genetics Revealing 5 Mutations in CEBPA Gene Associated With Acute Myeloid Leukemia.

BACKGROUND: Acute myeloid leukemia (AML) is an extremely heterogeneous malignant disorder; AML has been reported as one of the main causes of death in children. The objective of this work was to classify the most deleterious mutation in CCAAT/enhancer-binding protein-alpha (CEBPA) and to predict their influence on the functional, structural, and expression levels by various Bioinformatics analysis tools. METHODS: The single nucleotide polymorphisms (SNPs) were claimed from the National Center for Biotechnology Information (NCBI) database and then submitted into various functional analysis tools, which were done to predict the influence of each SNP, followed by structural analysis of modeled protein followed by predicting the mutation effect on energy stability; the most damaging mutations were chosen for additional investigation by Mutation3D, Project hope, ConSurf, BioEdit, and UCSF Chimera tools. RESULTS: A total of 5 mutations out of 248 were likely to be responsible for the structural and functional variations in CEBPA protein, whereas in the 3'-untranslated region (3'-UTR) the result showed that among 350 SNPs in the 3'-UTR of CEBPA gene, about 11 SNPs were predicted. Among these 11 SNPs, 65 alleles disrupted a conserved miRNA site and 22 derived alleles created a new site of miRNA. CONCLUSIONS: In this study, the impact of functional mutations in the CEBPA gene was investigated through different bioinformatics analysis techniques, which determined that R339W, R288P, N292S, N292T, and D63N are pathogenic mutations that have a possible functional and structural influence, therefore, could be used as genetic biomarkers and may assist in genetic studies with a special consideration of the large heterogeneity of AML.

HIV viral suppression in Oman: Encouraging progress toward achieving the United Nations 'third 90'.

OBJECTIVE: To assess the impact of capacity-building interventions introduced by the Oman National AIDS Programme on the quality of HIV care in the country. METHODS: HIV viral load (VL) suppression and loss to follow-up (LTFU) rates were calculated for the period before (in December 2015; n=1098) and after (in June 2017; n=1185) the introduction of the interventions: training, support, and care pathway development. Three HIV VL cuts-offs at last measurement in the year of interest were used to define VL suppression. RESULTS: In the intention-to-treat (ITT) analysis, rates of VL <200 copies/ml and <1000 copies/ml increased from 51.9% in 2015 to 65.5% in 2017 (relative risk (RR) 1.26, 95% confidence interval (CI) 1.17-1.36) and from 58.1% in 2015 to 70.9% in 2017 (RR 1.22, 95% CI 1.14-1.30), respectively; p<0.0001 for both. Similarly, in the on-treatment analysis, rates of VL <200 copies/ml and <1000copies/ml increased from 64.2% in 2015 to 76.9% in 2017 (RR 1.20, 95% CI 1.12-1.28) and from 71.9% in 2015 to 83.2% in 2017 (RR 1.16, 95% CI 1.10-1.22), respectively. Fewer patients were LTFU in 2017 than in 2015 (14.7% (157/1061) vs. 19.2% (188/981); RR 0.77, 95% CI 0.64-0.94). CONCLUSIONS: Achieving the UNAIDS target of 90% of HIV patients on treatment having VL suppression by 2020 is feasible in Oman.

Effect of folate oversupplementation on folate uptake by human intestinal and renal epithelial cells.

BACKGROUND: Folic acid [corrected] plays an essential role in cellular metabolism. Its deficiency can lead to neural tube defects. However, optimization of body folate homeostasis can reduce the incidence of neural tube defects and may decrease the risk of Alzheimer and cardiovascular diseases and cancer. Hence, food fortification and intake of supplemental folate are widespread. OBJECTIVE: We examined the effects of long-term folate oversupplementation on the physiologic markers of intestinal and renal folate uptake processes. DESIGN: Human-derived intestinal Caco-2 and renal HK-2 epithelial cells were maintained (5 generations) in a growth medium oversupplemented (100 micromol folic acid/L) or maintained under sufficient conditions (0.25 and 9 micromol folic acid/L). RESULTS: Carrier-mediated uptake of (3)H-folic acid (2 micromol/L) at buffer pH 5.5 (but not buffer pH 7.4) by Caco-2 and HK-2 cells maintained under the folate-oversupplemented condition was significantly (P<0.01) and specifically lower than in cells maintained under the folate-sufficient condition. This reduction in folic acid uptake was associated with a significant decrease in the protein and mRNA levels of the human reduced-folate carrier (hRFC) and a decrease in the activity of the hRFC promoter. It was also associated with a decrease in mRNA levels of the proton-coupled folate transporter/heme carrier protein 1 (PCFT/HCP1) and folate receptor (FR). CONCLUSIONS: Long-term oversupplementation with folate leads to a specific and significant down-regulation in intestinal and renal folate uptake, which is associated with a decrease in message levels of hRFC, PCFT/HCP1, and FR. This regulation appears to be mediated via a transcriptional mechanism, at least for the hRFC system.

Veratridine produces distinct calcium response profiles in mouse Dorsal Root Ganglia neurons.

Nociceptors are a subpopulation of dorsal root ganglia (DRG) neurons that detect noxious stimuli and signal pain. Veratridine (VTD) is a voltage-gated sodium channel (VGSC) modifier that is used as an "agonist" in functional screens for VGSC blockers. However, there is very little information on VTD response profiles in DRG neurons and how they relate to neuronal subtypes. Here we characterised VTD-induced calcium responses in cultured mouse DRG neurons. Our data shows that the heterogeneity of VTD responses reflects distinct subpopulations of sensory neurons. About 70% of DRG neurons respond to 30-100 µM VTD. We classified VTD responses into four profiles based upon their response shape. VTD response profiles differed in their frequency of occurrence and correlated with neuronal size. Furthermore, VTD response profiles correlated with responses to the algesic markers capsaicin, AITC and α, ß-methylene ATP. Since VTD response profiles integrate the action of several classes of ion channels and exchangers, they could act as functional "reporters" for the constellation of ion channels/exchangers expressed in each sensory neuron. Therefore our findings are relevant to studies and screens using VTD to activate DRG neurons.

Monitoring maternal, newborn, and child health interventions using lot quality assurance sampling in Sokoto State of northern Nigeria.

BACKGROUND: Maternal mortality ratio and infant mortality rate are as high as 1,576 per 100,000 live births and 78 per 1,000 live births, respectively, in Nigeria's northwestern region, where Sokoto State is located. Using applicable monitoring indicators for tracking progress in the UN/WHO framework on continuum of maternal, newborn, and child health care, this study evaluated the progress of Sokoto toward achieving the Millennium Development Goals (MDGs) 4 and 5 by December 2015. The changes in outcomes in 2012-2013 associated with maternal and child health interventions were assessed. DESIGN: We used baseline and follow-up lot quality assurance sampling (LQAS) data obtained in 2012 and 2013, respectively. In each of the surveys, data were obtained from 437 households sampled from 19 LQAS locations in each of the 23 local government areas (LGAs). The composite state-level coverage estimates of the respective indicators were aggregated from estimated LGA coverage estimates. RESULTS: None of the nine indicators associated with the continuum of maternal, neonatal, and child care satisfied the recommended 90% coverage target for achieving MDGs 4 and 5. Similarly, the average state coverage estimates were lower than national coverage estimates. Marginal improvements in coverage were obtained in the demand for family planning satisfied, antenatal care visits, postnatal care for mothers, and exclusive breast-feeding. Antibiotic treatment for acute pneumonia increased significantly by 12.8 percentage points. The majority of the LGAs were classifiable as low-performing, high-priority areas for intensified program intervention. CONCLUSIONS: Despite the limited time left in the countdown to December 2015, Sokoto State, Nigeria, is not on track to achieving the MDG 90% coverage of indicators tied to the continuum of maternal and child care, to reduce maternal and childhood mortality by a third by 2015. Targeted health system investments at the primary care level remain a priority, for intensive program scale-up to accelerate impact.

Vitamin B1 (thiamine) uptake by human retinal pigment epithelial (ARPE-19) cells: mechanism and regulation.

Retinal abnormality and visual disturbances occur in thiamine-responsive megaloblastic anaemia (TRMA), an autosomal recessive disorder caused by mutations in the human thiamine transporter-1 (hTHTR-1). Human retinal pigment epithelial cells play a pivotal role in supplying thiamine to the highly metabolically active retina but nothing is known about the mechanism, regulation or biological processes involved in thiamine transport in these cells. To address these issues, we used human-derived retinal pigment epithelial ARPE-19 cells to characterize the thiamine uptake process. Thiamine uptake is energy- and temperature-dependent, pH-sensitive, Na+-independent, saturable at both the nanomolar (apparent Km, 30 +/- 5 nM) and the micromolar (apparent Km, 1.72 +/- 0.3 microM) concentration ranges, specific for thiamine and sensitive to sulfhydryl group inhibition. The diuretic amiloride caused a concentration-dependent inhibition in thiamine uptake, whereas the anti-trypanosomal drug, melarsoprol, failed to affect the uptake process. Both hTHTR-1 and hTHTR-2 are expressed in ARPE-19 cells as well as in native human retinal tissue with expression of the former being significantly higher than that of the latter. Uptake of thiamine was adaptively regulated by extracellular substrate level via transcriptionally mediated mechanisms that involve both hTHTR-1 and hTHTR-2; it was also regulated by an intracellular Ca2+-calmodulin-mediated pathway. Confocal imaging of living ARPE-19 cells expressing TRMA-associated hTHTR-1 mutants (D93H, S143F and G172D) showed various expression phenotypes. These results demonstrate for the first time the existence of a specialized and regulated uptake process for thiamine in a cellular model of human retinal pigment epithelia that involves hTHTR-1 and hTHTR-2. Further, clinically relevant mutations in hTHTR-1 lead to impaired cell surface expression or function of the transporter in retinal epithelial ARPE-19 cells.

Mechanism of nicotinic acid transport in human liver cells: experiments with HepG2 cells and primary hepatocytes.

This study reports on the functional expression of a specific, high-affinity carrier-mediated mechanism for the transport of niacin (nicotinic acid) in human liver cells. Both human-derived liver HepG2 cells and human primary hepatocytes were used as models in these investigations. The initial rate of transport of nicotinic acid into HepG2 cells was found to be acidic pH, temperature, and energy dependent; it was, however, Na(+) independent in nature. Evidence for the existence of a carrier-mediated system that is specific for [(3)H]nicotinic acid transport was found and included the following: 1) saturability as a function of concentration with an apparent K(m) of 0.73 +/- 0.16 microM and V(max) of 25.02 +/- 1.45 pmol.mg protein(-1).3 min(-1), 2) cis-inhibition by unlabeled nicotinic acid and nicotinamide but not by unrelated organic anions (lactate, acetate, butyrate, succinate, citrate, and valproate), and 3) trans-stimulation of [(3)H]nicotinic acid efflux by unlabeled nicotinic acid. Transport of the vitamin into human primary hepatocytes occurs similarly via an acidic pH-dependent and specific carrier-mediated process. Inhibitors of the Ca(2+)-calmodulin-mediated pathway (but not modulators of the PKC-, PKA-, and protein tyrosine kinase-mediated pathways) inhibited nicotinic acid transport into both HepG2 cells and human primary hepatocytes. Maintenance of HepG2 cells (for 48 h) in growth medium oversupplemented with nicotinic acid (or nicotinamide) did not affect the subsequent transport of [(3)H]nicotinic acid into HepG2 cells. These results show, for the first time, the existence of a specific and regulated membrane carrier-mediated system for nicotinic acid transport in human liver cells.

Intestinal absorption of water-soluble vitamins: an update.

PURPOSE OF REVIEW: The molecular biology revolution has led to a significant improvement in our understanding of biological and physiological processes. Such expansion of knowledge has also covered the field of intestinal absorption of water-soluble vitamins and is the subject of this review. RECENT FINDINGS: Impressive progress has been made in the understanding of the mechanisms and regulation of transport of water-soluble vitamins at the cellular and molecular levels. In addition, the 5' regulatory regions of the genes that encode a number of the involved transporters have been cloned and characterized in vitro and in vivo in transgenic mice, thus providing important information about transcriptional regulation of these events. Furthermore, confocal imaging of live intestinal epithelial cells has led to significant progress in understanding the mechanisms involved in intracellular trafficking and membrane targeting of the carrier proteins and how clinical mutations lead to interference with transport. Finally, the identification in the large intestine of efficient and specialized carrier-mediated systems that are capable of absorbing a number of the bacterially synthesized vitamins (thiamin, folate, biotin, riboflavin, pantothenic acid) has raised the possibility that this source of vitamins may play a role in regulating (fine tuning) the normal body homeostasis of these vitamins, and especially the vitamin level in the local colonocytes. SUMMARY: Water-soluble vitamin absorption involves regulated and specific mechanisms. Interference with the function of these mechanisms may lead to deficiency. The large intestine is capable of absorbing water-soluble vitamins that are synthesized by the normal microflora.