SF Concentrations Research Articles

Physiologically-based pharmacokinetic (PBPK) modeling of sodium fluorescein (SF) blood clearance for assessing hepatic ischemia-reperfusion injury (IRI)

Rationale: Quantitative analysis of bile formation machinery has potential to assess the viability of a liver for transplantation. Recently, we demonstrated the utility of the fluorescent dye SF by showing that the bile-to-plasma fluorescence ratio inversely correlated with warm ischemia time in rats and associated this finding with IRI-induced intracellular internalization of the MRP2 transporter (PMID: 35700191). However, it is unclear how much SF is cleared by active MRP2 in relation to other contributing factors associated with complex in vivo physiology. We hypothesize that PBPK modeling can account for dominant vascular, tissue, and biochemical processes contributing to SF clearance, including MRP2 activity, and simulate diminished liver function in IRI leading to decreased disposition of SF in the bile. Methods: We considered previously published data of SF fluorescence intensity in blood, plasma, and bile over time in rats under control and IRI conditions. To model these data, we performed SF calibration experiments and converted these data from fluorescence to concentration using standard curves generated from nonlinear regression. We fit an empirical triple-exponential function to the calibrated control blood SF concentration data and used this function as an input for a mechanistic liver-centric PBPK model. The PBPK model accounts for three regions in the liver (blood, hepatocytes, bile) and major physiological processes, including kinetics of basolateral and canalicular transporters governing SF dynamics in different liver regions. We fit this model to the control SF concentration data in the bile using a pseudo-Monte Carlo strategy. Model parameters relating to maximal velocity for the transporters were allowed to vary, while all others were fixed to physiologic values. Results: The PBPK model was able to provide a good fit to control bile SF concentration data. The input model for blood SF concentration was able to predict plasma SF concentration related by a variable partition coefficient, which led to a large difference between plasma and blood SF concentrations at high SF concentrations but diminished at lower concentrations. We simulated the IRI condition by decreasing MRP2 activity, which showed that SF blood clearance through hepatocytes into bile is highly sensitive to changes in the activity of MRP2, consistent with our hypothesis that SF clearance data and PBPK modeling could quantify the effect of IRI on MRP2 activity. These simulations showed a larger decrease in SF concentration in bile relative to the increase in blood resulting in a lower bile-to-blood SF ratio. Conclusions: Based on our experimental data, we developed a liver-centric PBPK model for the blood clearance of SF through hepatocytes and bile and used this model to simulate the contribution of MRP2 to diminished secretion of SF into the bile as measured following IRI. MCW/BME-FP00022381 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Iron Status and Associated Factors among Canadian Women: Results from the Canadian Health Measures Survey

BackgroundIron deficiency and overload may negatively impact women’s health. There has been limited assessment of iron status and its associated factors among Canadian women. ObjectivesThis study investigated associations of various sociodemographic, lifestyle, medication, and dietary factors with body iron stores among pre- and postmenopausal women in Canada. MethodsAnalyses were conducted using cross-sectional, nationally representative survey and biomarker data from women aged 20–79 y (n = 6362) in the Canadian Health Measures Survey (2009–2017). Body iron stores were assessed by measuring serum concentrations of ferritin (SF). Information on potential correlates was collected during an in-home interview. Multivariable linear regression analyses were performed to evaluate associations with SF concentration, and logistic regression was used to estimate associations with iron deficiency (SF <15 μg/L) or elevated iron stores (SF >150 μg/L). ResultsGeometric mean SF concentrations were significantly higher in postmenopausal than in premenopausal women (73.2 versus 33.8 μg/L; P < 0.001). The prevalence of iron deficiency among pre- and postmenopausal women was 16.0% and 4.0%, respectively, whereas that of elevated iron stores was 2.7% and 21.0%, respectively. After simultaneous adjustment for multiple factors, including high-sensitivity CRP (inflammation marker), we found that age, East/Southeast Asian (versus White) race/ethnicity, alcohol, and red meat consumption were positively associated with SF concentration among pre- and postmenopausal women. In addition, aspirin use and dairy consumption were inversely associated with SF concentration among postmenopausal women only. Similar patterns were observed for associations with elevated iron stores among postmenopausal women, whereas higher grain consumption was associated with an increased prevalence of iron deficiency among premenopausal women. ConclusionsSociodemographic, lifestyle, medication, and dietary factors are correlated with iron status determined by SF concentration among Canadian women. The findings may have implications for intervention strategies aimed at optimizing body iron stores in pre- and postmenopausal women.

Safety and efficacy of deferasirox in patients with transfusion-dependent thalassemia: A 4-year single-center experience

This study was organized to determine the efficacy and safety of deferasirox (DFX) in reducing the SF of patients with transfusion-dependent thalassemia (TDT). This is a retrospective, descriptive study of 101 transfusion- dependent patients with thalassemia major who were followed for 48 months. Twenty-nine patients who used an alternative chelator either alone or combined, who were not compliant to the treatment, changed the drug due to adverse reactions, and had multiple transfusions and did not complete 4 years of DFX use were excluded. A total 72 out of 101 patients completed the study. SF decreases were noted for the 6-12 and >18-year age groups, from a median of 1532 ng/mL to 1190 ng/mL, and from 1386 ng/mL to 1165 ng/mL, respectively (p > 0.05). The proportion of patients with SF concentrations >2000 ng/mL is decreased (29% at baseline decreased to 15% at the end of the study) during the 48 months. The median SF of those who used <30 mg/kg/day (n = 38) increased from 767 ng/mL to 1006 ng/mL, whereas the >30 mg/kg/day (n = 34) group’s SF concentrations decreased from a median of 1575 ng/mL to 1209 ng/mL (p = 0.029). The decrease of median SF values for Syrian patients was statistically significant (p = 0.043). Most common adverse events were gastric irritation symptoms (19.4%). The total DFX discontinuation ratio was calculated as 9.7%. Although dosages between 25-30 mg/kg/day are adequate to stabilize SF concentrations higher dosages are needed to achieve a statistically significant decrease.

Surfactin-reinforced gelatin methacrylate hydrogel accelerates diabetic wound healing by regulating the macrophage polarization and promoting angiogenesis

Chronic wound healing is a severe complication that threatens the life of diabetic patients because of the damaged skin microvasculature and prolonged inflammation at the wound site. Novel wound dressing materials with the outstanding wound repair specialty are highly needed. Herein, a new hydrogel was developed with attractive capabilities in stiffness, swelling, self-healing, and biocompatibility, for the treatment of chronic wound in diabetes. The hybrid hydrogel was achieved by firstly synthesizing gelatin methacrylate (GelMA), then microbial lipopeptide-surfactin (SF) together with the photoinitiator were added before being crosslinked with 60 s of UV (i.e., GelMA-SF hydrogels). With the increase of SF concentrations, the porosity and tensile modulus of GelMA-SF hydrogels decreased, while the ultimate stress and compression modulus significantly increased compared with GelMA hydrogels. The feasibility of GelMA-SF hydrogels was tested by treating skin wounds in type I diabetic rats without coverage in vivo. For the first time, the study introduced SF to the GelMA network and revealed the mechanisms of the GelMA-SF hydrogels to promote diabetic wound healing via regulating macrophage polarization and promoting angiogenesis. The dynamic multifunctional hydrogel materials show great promise in the regeneration of difform wounds, especially, in situations with impaired angiogenesis and persistent inflammatory responses.

Iron intake and iron status during pregnancy and risk of congenital heart defects: A case-control study

BackgroundThe relationships between iron nutritional status and congenital heart defects (CHDs) among humans are still unclear. This study aimed to explore the associations of maternal iron intake during pregnancy and maternal and neonatal iron status with CHDs. MethodsThis hospital-based case-control study analyzed 474 cases and 948 controls in Shaanxi China. Eligible women waiting for delivery in the hospital were interviewed to report their diets and characteristics during pregnancy. We conveniently collected maternal blood before delivery and neonatal cord blood to get a subgroup of 50 cases and 100 controls. Mixed logistic regression models were used to estimate ORs (95%CIs) for CHDs associated with iron intake. Mixed linear regression models were used to assess the relationships between CHDs and iron status. ResultsMothers whose fetuses have CHDs were less likely to have higher intakes of total iron and heme iron during pregnancy, and the tests for linear trend were significant (all P < 0.05). Mothers whose fetuses have CHDs were less likely to take iron supplements during pregnancy (OR = 0.28, 95%CI: 0.21, 0.36) and during the first trimester (OR = 0.32, 95%CI: 0.12, 0.84). Maternal SF and Hb concentrations before delivery were lower and maternal sTfR/SF before delivery was higher among the cases than the controls. ConclusionsMothers whose fetuses have CHDs are less likely to have higher intakes of total iron and heme iron and take iron supplements during pregnancy compared to their counterparts. Maternal iron status before delivery is low among mothers whose fetuses have CHDs.

Optimization of Physical, Optical and Barrier Properties of Films Made from Cassava Starch and Rosemary Oil

In this study, films from cassava starch and rosemary oil were prepared by using the casting method. Glycerol was used as plasticizer and tween 80 as surfactant. The influence of Cassava starch (Cs), Rosemary oil (Ro), Surfactant (Sf) concentrations and Thickness of film (Tf) on the mechanical, optical, and barrier properties of cassava starch films was studied applying the Response Surface Methodology. The response variables were optimized by using second order polynomial models with satisfactory fit and coefficient of determination (R2) values (> 81%). The optimized conditions with the goal of maximizing mechanical properties and minimizing barrier and optical properties and desirability function (0.9796) were Cs = 3 g/100 g solution, Ro = 4 g/100 g Cs, Sf = 69 g/100 g Ro and Tf = 0.05 ± 0.001 mm. The films produced under these conditions displayed high mechanical strength (16.7 MPa), young´s modulus (2911.4 MPa), low elongation at break (0.2%), low water vapor transmission (0.8 × 10−14 g/Pa s m), low solubility (33.24%), and low opacity (16%). These results provided good mechanical, barrier, and optical properties, compared to films based on other starch resources.

Critical micelle concentration and particle size determine adjuvanticity of cyclic lipopeptides.

Cyclic lipopeptides such as surfactin and polymyxin have potent mucosal adjuvant properties. Cyclic lipopeptides are tensioactive compounds, but the relationship between adjuvanticity and surface activity is unknown. Here, we show that the critical micelle concentration (cmc) of surfactant and particle size of the surfactant-protein complex are important determinants of cyclic lipopeptide adjuvanticity. We found that the diameter of cyclic lipopeptide-ovalbumin (OVA) complex particles was significantly larger than that in the solutions of OVA alone at cyclic lipopeptide concentrations above the cmc. OVA-specific antibody titres in mice immunized intranasally with OVA and a cyclic lipopeptide at concentrations above its cmc were significantly higher than those in mice immunized with OVA plus the same dose of the cyclic lipopeptide but administered with formulations in which cyclic lipopeptide concentration was below the cmc. Thus, the concentration of the cyclic lipopeptide in the formulation at immunization, but not its overall dose, was critical for its adjuvanticity. Furthermore, two types of aggregates, the cyclic lipopeptide simplex micelles and the cyclic lipopeptide-OVA complex micelles, were found in formulations with SF concentrations above its cmc. Degranulation of mast cells exposed to SF simplex micelles was more pronounced when SF concentration was above the cmc. In conclusion, our study showed that surface activity properties, such as the cmc and the size of surfactant-protein complex, contribute to the adjuvanticity of cyclic lipopeptides. Our study proposes a novel idea that cmc is a key parameter for tensioactive adjuvants.

Concentrations of synovial fluid biomarkers and the prediction of knee osteoarthritis 16years after anterior cruciate ligament injury.

To describe the longitudinal patterns of release, and investigate the association between a set of synovial fluid biomarkers at the acute and chronic stage and the development of radiographic knee osteoarthritis (OA) after an anterior cruciate ligament (ACL) injury. Synovial fluid was aspirated from the acutely ACL-injured knee within the first 2weeks (acute samples), and yearly (chronic samples) up to 7.5 years after injury in 88 subjects (60% men). Non-injured subjects (n=12) were used as reference group. Aggrecan, cartilage oligomeric matrix protein (COMP), matrix metalloproteinase (MMP)-3 and tissue inhibitor of metalloproteinase (TIMP)-1 in synovial fluid were quantified by immunoassays. The presence of radiographic tibiofemoral (TF) or patellofemoral (PF) OA [Kellgren and Lawrence (K&L) ≥2] was examined with weight-bearing knee radiography 16 years after the ACL injury. The average acute and chronic SF concentrations of COMP and aggrecan were elevated in comparison with the reference group (P<0.001). The levels of COMP and aggrecan clearly decreased approximately half a year after the ACL injury, and returned to reference values during the 7.5 years of follow-up. Using logistic regression analysis neither acute nor chronic concentrations of the four biomarkers were associated with the development of radiographic knee OA at the 16 year follow-up. Increased synovial fluid concentrations of aggrecan and COMP was related to knee injury, but acute and chronic synovial fluid concentrations of aggrecan, COMP, MMP-3 and TIMP-1 failed to predict knee OA 16 years after ACL injury.

AB0087 Higher levels of th17/23, TH2 and proinflammatory cytokines levels in synovial fluid of rheumatoid arthritis compared with psoriatic arthritis

BackgroundRheumatoid arthritis (RA) and Psoriatic arthritis (PsA) are two chronic inflamatory diseases mediated by the immune system with joints as main targets. Both diseases seem to exhibit a Th1/Th17 pattern,...

Body iron stores and the risk of type 2 diabetes in middle-aged men

We investigated the risk of type 2 diabetes mellitus (T2DM) over a wide range of body iron stores. Prospective cohort of 1613 men in the Kuopio Ischemic Heart Disease Risk Factor study, aged 42-60 years, free of T2DM and hereditary hemochromatosis at baseline in 1984-1989. Baseline serum ferritin (sF) and serum-soluble transferrin receptor (sTfR) concentrations were used to predict incident T2DM. T2DM was assessed by questionnaires, blood glucose measurements, and medication reimbursement register. There were 331 cases of incident T2DM during the mean follow-up of 16.8 years (27,098 person-years). At baseline, subjects who later developed T2DM had average sF concentrations of 191 μg/l (S.D. 155) vs 151 μg/l (S.D. 119) among those who remained healthy, P<0.001. In a multivariate-adjusted logistic regression, each 100 μg/l increase in sF corresponded to an average of 14% increased (odds ratio=1.14, 95% CI 1.03-1.26, P=0.009) risk of developing T2DM. In a Cox regression, a markedly increased risk of developing T2DM was observed from the fourth sF quintile (185 μg/l, the median) upward (hazard ratio (HR) first vs fifth quintile=1.5, 95% CI 1.0-2.2, P-trend=0.05). In a corresponding Cox model in sTfR, the subjects in the third quintile (1840 μg/l, the median) had the least risk (HR=0.63, 95% CI 0.42-0.97, P=0.04). Body iron within the sF reference range is not an important determinant of T2DM risk, whereas high normal and above is associated with markedly increased risk. Iron depletion toward iron deficiency as assessed by sTfR is not protective against T2DM. A rule of thumb safe range could be 30-200 μg/l of sF.

Urease from Helicobacter pylori is inactivated by sulforaphane and other isothiocyanates

Infections by Helicobacter pylori are very common, causing gastroduodenal inflammation including peptic ulcers, and increasing the risk of gastric neoplasia. The isothiocyanate (ITC) sulforaphane [SF; 1-isothiocyanato-4-(methylsulfinyl)butane] derived from edible crucifers such as broccoli is potently bactericidal against Helicobacter, including antibiotic-resistant strains, suggesting a possible dietary therapy. Gastric H. pylori infections express high urease activity which generates ammonia, neutralizes gastric acidity, and promotes inflammation. The finding that SF inhibits (inactivates) urease (jack bean and Helicobacter) raised the issue of whether these properties might be functionally related. The rates of inactivation of urease activity depend on enzyme and SF concentrations and show first order kinetics. Treatment with SF results in time-dependent increases in the ultraviolet absorption of partially purified Helicobacter urease in the 260–320 nm region. This provides direct spectroscopic evidence for the formation of dithiocarbamates between the ITC group of SF and cysteine thiols of urease. The potencies of inactivation of Helicobacter urease by isothiocyanates structurally related to SF were surprisingly variable. Natural isothiocyanates closely related to SF, previously shown to be bactericidal (berteroin, hirsutin, phenethyl isothiocyanate, alyssin, and erucin), did not inactivate urease activity. Furthermore, SF is bactericidal against both urease positive and negative H. pylori strains. In contrast, some isothiocyanates such as benzoyl-ITC, are very potent urease inactivators, but are not bactericidal. The bactericidal effects of SF and other ITC against Helicobacter are therefore not obligatorily linked to urease inactivation, but may reduce the inflammatory component of Helicobacter infections.

Technical Note: Can the sulfur hexafluoride tracer gas technique be used to accurately measure enteric methane production from ruminally cannulated cattle?

An experiment was conducted to determine whether using ruminally cannulated cattle affects the estimate of enteric methane (CH(4)) emissions when using the sulfur hexafluoride (SF(6)) tracer technique with samples taken from a head canister. Eleven beef cattle were surgically fitted with several types of ruminal cannula (2C, 3C, 3C+washer, 9C; Bar Diamond, Parma, ID). The 2C and 3C models (outer and inner flanges with opposite curvature) had medium to high leakage, whereas the 9C models (outer and inner flanges with the same curvature) provided minimum to moderate leakage of gas. A total of 48 cow-day measurements were conducted. For each animal, a permeation tube containing sulfur hexafluoride (SF(6)) was placed in the rumen, and a sample of air from around the nose and mouth was drawn through tubing into an evacuated canister (head canister). A second sample of air was collected from outside the rumen near the cannula into another canister (cannula canister). Background concentrations were also monitored. The methane (CH(4)) emission was estimated from the daily CH(4) and SF(6) concentrations in the head canister (uncorrected). The permeation SF(6) release rate was then partitioned based on the proportion of the SF(6) concentration measured in the head vs. the cannula canister. The CH(4) emissions at each site were calculated using the two release rates and the two CH(4):SF(6) concentration ratios. The head and cannula emissions were summed to obtain the total emission (corrected). The difference (corrected - uncorrected) in CH4 emission was attributed to the differences in CH(4):SF(6) ratio at the 2 exit locations. The proportions of CH(4) and SF(6) recovered at the head were greater (P < 0.001) for the 9C cannulas (64% and 66%) compared with the other cannulas, which were similar (P > 0.05; 2C, 6% and 4%; 3C, 17% and 15%; 3C+washer, 19% and 14%). Uncorrected CH(4) emissions were ± 10% of corrected emissions for 53% of the cow-day measurements. Only when more than 80% of the SF(6) escaped via the rumen did the difference between the uncorrected and corrected CH(4) emissions exceed 20%. We concluded that using cannulated cattle introduces more variability into the SF(6) technique used with a head canister, a technique that is already highly variable. Thus, use of cannulated animals is not recommended when using the SF(6) technique with head canister. However, if cannulated cattle are used, the cannulas need to be tight-fitting to minimize leakage, and large animal numbers are needed to overcome the additional variability.

Synovial cytokine expression in psoriatic arthritis and associations with lymphoid neogenesis and clinical features

IntroductionPsoriatic arthritis (PsA) is an autoantibody-negative immune-mediated disease in which synovial lymphoid neogenesis (LN) occurs. We determined whether LN is associated with specific patterns of inflammatory cytokine expression in paired synovial tissue (ST) and fluid (SF) samples and their potential correlation with the clinical characteristics of PsA.MethodsST and paired SF samples were obtained from the inflamed knee of PsA patients. ST samples were immunostained with CD3 (T cell), CD20 (B cell), and MECA-79 (high endothelial vessels). Total ST mRNA was extracted, and the gene expression of 21 T-cell-derived and proinflammatory cytokines were measured with quantitative real-time PCR. SF concentrations of Th1, Th2, Th17, and proinflammatory cytokines were determined with the Quantibody Human Th17 Array. Clinical and biologic data were collected at inclusion and after a median of 27 months of follow-up.ResultsTwenty (43.5%) of 46 patients had LN. Only two genes showed differences (Wilcoxon test, P < 0.06) in ST between LN-positive and LN-negative patients: interleukin-23A (IL-23A) (P = 0.058) and transforming growth factor-beta (TGF-β1) (P = 0.050). IL-23A expression was higher, and TGF-β1 expression was lower in LN-positive patients. ST IL-15 mRNA showed a nonsignificant trend toward higher expression in LN-positive patients, and SF IL-15 protein levels were significantly higher in LN-positive patients (P = 0.002). In all PsA patients, IL-23A mRNA expression correlated with C-reactive protein (CRP) (r = 0.471; P = 0.001) and swollen-joint count (SJC) (r = 0.350; P = 0.018), whereas SF levels of IL-6 and CC chemokine-ligand 20 (CCL-20) correlated with CRP levels (r = 0.377; P = 0.014 and r = 0.501; P < 0.0001, respectively).ConclusionsThese findings suggest differences in the cytokine profile of PsA patients with LN, with a higher expression of IL-23A and IL-15 and a lower expression of TGF-β1. In the entire group of patients, IL-23 ST expression and CCL20 SF levels strongly correlated with markers of disease activity. This cytokine pattern was not accompanied by gross clinical or biologic differences between LN-positive and -negative patients. Taken together, these results suggest a role of the IL-17/IL-23 cytokine axis in synovial LN in PsA.

Peripheral airway function in childhood asthma, assessed by single-breath He and SF6 washout.

To assess whether the peripheral airways are involved in pediatric asthma, 10 asthmatic children (aged 8-15 years), hyperresponsive to dry-air hyperventilation challenge (DACh), performed spirometry and a vital capacity He/SF(6) single-breath washout test at rest, after DACh, and after beta(2)-therapy. The normalized phase III slopes (Sn(III)) of the expired He and SF(6) concentrations served as measures of overall ventilation inhomogeneity, and the (SF(6) - He) Sn(III) difference served to indicate where along the peripheral airways obstruction occurs. While a greater increase in the He vs. SF(6) slope indicates that obstruction has occurred in the vicinity of the acinar entrance, the reverse suggests obstruction deeper in the intraacinar airways. The mean (SD) fall in FEV(1) after DACh was 35 (14)%. Both He and SF(6) Sn(III) increased significantly (P < 0.05) after the challenge, and were restituted after beta(2)-therapy (P < 0.05). After DACh, Sn(III) increased more for He than for SF(6), resulting in a negative (SF(6) - He) Sn(III) difference (P < 0.01), which was restituted after beta(2)-therapy (P < 0.05). Even though there was no correlation between baseline FEV(1) and the magnitude of the subsequent fall in this parameter after DACh (r(2) = 0.04; n.s.), a strong correlation was found between the (SF(6) - He) Sn(III) difference at rest and its change after DACh (r(2) = 0.81; P < 0.001). We conclude that airways close to the acinar entrance participate in the airway response to DACh in asthmatic children. The magnitude of this peripheral airway response is related to the severity of resting peripheral airway dysfunction.

Serum folic acid levels in epileptic mothers and their relationship to congenital malformations

Folic acid levels during pregnancy and in pre-pregnancy were determined in 51 epileptic mothers and those of matched controls. The serum folic acid (SF) levels of epileptic mothers were significantly lower than those of controls in all study periods. The SF levels of mothers of malformed offspring were significantly lower than those of mothers of normal offspring in the 1st and 2nd trimesters of pregnancy. These results suggest that SF concentrations are implicated in congenital malformations in the offspring of epileptic mothers.