[Sini Decoction inhibits TLR4/NF-κB signaling pathway to improve airway remodeling of allergic asthmatic mice]

This study aims to explore the effect of Sini Decoction on Toll-like receptor 4(TLR4)/nuclear factor-κB(NF-κB) signaling pathway in the mice with allergic asthma(AA). Forty-eight SPF-grade BALB/c mice were randomly assigned into a blank control group, a model group, a dexamethasone group, and high-, medium-, and low-dose Sini Decoction groups, with 8 mice in each group. The sensitization solution made of ovalbumin and aluminum hydroxide powder was injected intraperitoneally in other groups except the blank control group which was injected with an equal volume of normal saline. The solution(or normal saline) was injected three times in total with an interval of 7 days. At the same time of sensitization, external cold stimulation and ice water were administered in a 4 ℃ climate box for 20 min every day. After modeling, the mice in each group were administrated with corresponding drugs by gavage for 3 weeks. At the end of administration, pentobarbital sodium(30 mg·kg~(-1)) was used for anesthesia, and then the samples were collected for the determination of various indexes. The phenol red test was conducted to evaluate tracheal excretion function. The histopathological changes of lung tissue were observed via hematoxylin-eosin(HE) staining. Masson staining was employed to reveal the deposition of blue collagen fibers around bronchi in lung tissue and the area occupied by blue collagen fibers was calculated. Immunofluorescence method was used to measure the expression of bronchial type Ⅰ collagen(Col-Ⅰ) and α-smooth muscle actin(α-SMA). The protein and mRNA levels of TLR4, NF-κB, cysteinyl aspartate specific proteinase-1(caspase-1), and interleukin-13(IL-13) were determined by Western blot and real-time fluorescence quantitative polymerase chain reaction(real-time PCR), respectively. Compared with the model group, Sini Decoction significantly increased the phenol red excretion from trachea, lowered the lung inflammation score, reduced subepithelial collagen deposition, and decreased Col-Ⅰ and α-SMA levels. Furthermore, the decoction down-regulated the protein and mRNA levels of TLR4, NF-κB, caspase-1, and IL-13 in mouse lung tissue. In conclusion, Sini Decoction can improve air remodeling by inhibiting the TLR4/NF-κB signaling pathway.

Differential Impacts of Phenol Red on Benzo[a]pyrene and Dexamethasone-Modified Cytochrome P450s in Human Cancer Cells

<b>Background and Objective:</b> Phenol red, the pH indicator in cell culture media, influences the expression of cytochrome P450s (CYPs) in cell lines. This study aimed to examine how phenol red modified CYP induction by benzo[<i>a</i>]pyrene and dexamethasone in human hepatocarcinoma (HepG2), colorectal adenocarcinoma (Caco-2) and choriocarcinoma (BeWo) cells. <b>Materials and Methods:</b> The cells (1×10<sup>5</sup> cells/well in a 24-well plate) were incubated with benzo[<i>a</i>]pyrene (0.1, 1 and 10 μM) or dexamethasone (1, 5 and 10 μM) in either phenol red or phenol red-free media for 24 hrs. The mRNA expression of CYPs was determined by Real-Time Polymerase Chain Reaction (RT/qPCR). <b>Results:</b> Phenol red enhanced expression of benzo[<i>a</i>]pyrene-induced CYP1A2 inHepG2 and BeWo cells and suppressed benzo[<i>a</i>]pyrene-induced CYP2A6 expression in HepG2 and Caco-2 cells, benzo[<i>a</i>]pyrene induced CYP2B6 expression in HepG2 cells and benzo[<i>a</i>]pyrene- and dexamethasone-induced CYP3A4 expression in HepG2 and Caco-2 cells. The expression of CYP3A5 was affected differently in HepG2 and Caco-2 cell lines. Phenol red enhanced benzo[<i>a</i>]pyrene- and dexamethasone-induced CYP3A5 expression in Caco-2 cells but suppressed benzo[<i>a</i>]pyrene- and dexamethasone-induced CYP3A5 expression in HepG2 cells. <b>Conclusion:</b> Phenol red differentially influenced expression of benzo[<i>a</i>]pyrene- and dexamethasone-induced CYP1A2, CYP2A6, CYP2B6, CYP3A4 and CYP3A5 mRNAs in HepG2, Caco-2 and BeWo cells. Therefore, the inclusion of phenol red in cell culture media is of concern in studies of drug and xenobiotic metabolism via CYPs in human cell line models.

Reversible Nontoxic Thermochromic Microcapsules

Thermochromic materials exhibit a color change in response to a change in temperature. Creating nontoxic microcapsules containing thermochromic materials for applications in ink and film materials is historically challenging. In this study, we develop a nontoxic chlorophenol red (CPR)-water thermochromic system and its microcapsules with silicone shells via a reaction between water and octadecyltrichlorosilane (OTS) at the interface of a w/o emulsion. The obtained microcapsules exhibit a clear color change with full reversibility and are successfully used as inks by screen printing and as additives in films. Nontoxicity of both microcapsules and films is demonstrated through cell cytotoxicity assays. These features make these novel materials applicable to the next generation of intelligent sensors, coating, and food packaging materials.

Potential colorimetric detection of cancer cells using Phenol Red

The objective of this research is to examine the relationship between the color changes of phenol red and the growth of cancer cells, i.e., HeLa and DU145 cells, over a specific period of time. Normal mouse skin fibroblasts (L929 cells) were used as a reference. In this research, the color changes of phenol red due to the acidification of the cell culture medium from the growth of the cells over a period of nine hours showed potential colorimetric characteristics of cancer cells. The color changes of phenol red were observed using visible absorbance spectroscopy. The transformation of the absorbance spectra into coefficients of determination against the examined range of wavelengths created a distinctive spectral signature that signifies phenol red discoloration in cancer and normal cell culture lines.

Foliar penetration enhanced by biosurfactant rhamnolipid

With recent environmental and health concerns, biosurfactants have obtained increasing interest in replacing conventional surfactants for diverse applications. In agriculture, the use of surfactant in stimulating foliar uptake is mainly for wetting leaf surface, resisting deposition/evaporation, enhancing penetration across cuticular membrane (CM) and translocation. This paper aimed to address the improved foliar uptake by rhamnolipid (RL) in comparison with the currently used alkyl polyglucoside (APG). As found, compared with APG at 900mg/L (1×critical micellar concentration, CMC), RL at a much lower concentration of 50mg/L (1×CMC) showed much better wettability and surface activity, indicative of its high effectiveness as surfactants. Its performance on resistance to deposition and evaporation was at least as same as APG. Moreover, RL could significantly improve the penetration of herbicide glyphosate and other two small water-soluble molecules (phenol red and Fe(2+)) across CM at an equivalent efficiency as APG at 1×CMC. Finally, the greatly enhanced herbicidal actitivity of glyphosate on greenhouse plants confirmed that RL and APG could both enhance the foliar uptake including translocation. Overall, RL should be more applicable than APG in agriculture due to its more promising properties on health/environmental friendliness.

Red algal bromophenols as glucose 6-phosphate dehydrogenase inhibitors

Five bromophenols isolated from three Rhodomelaceae algae (Laurencia nipponica, Polysiphonia morrowii, Odonthalia corymbifera) showed inhibitory effects against glucose 6-phosphate dehydrogenase (G6PD). Among them, the symmetric bromophenol dimer (5) showed the highest inhibitory activity against G6PD.

Targeting insulin amyloid assembly by small aromatic molecules: toward rational design of aggregation inhibitors

Amyloid fibril formation is a common event in more than twenty human diseases and in some normal physiological processes. The mechanism of this ordered aggregation process and the molecular forces driving it are therefore of great importance. One of the strategies used in this field is targeting the fibrillization process by different factors, like, short peptides, organic molecules, etc. Here, we targeted insulin fibril formation by a range of small aromatic molecules, with different numbers of aromatic rings and various substituent groups. Using Thioflavin T fluorescence assay and transmission electron microscopy, we found that all dicyclic and tricyclic compounds in our screen were efficient inhibitors of insulin fibril formation. A common notion regarding amyloid inhibitors is that two functional groups are essentials for interfering with the amyloid formation process; a recognition motif and a bulky group for inducing a steric interference. However, here, we showed that some monocyclic compounds as small as toluene were also found to inhibit fibrillization. In addition, we found that substituent of benzene ring have a great influence on the inhibitory potency. Specifically, cyano, methyl and nitro groups increased the inhibitory potency. The results introduced here may contribute to future rational design of amyloid inhibitors.

Hormonal and purinergic stimulation of bicarbonate secretion in oviducts of rhesus monkey

Because an increase in the HCO(3)(-) concentration of oviductal liquid at midcycle is believed to markedly enhance fertility, we have studied active secretion of HCO(3)(-) across highly differentiated cultures of monkey oviductal epithelium. Cultured cell sheets were mounted in Ussing chambers and bathed in medium containing 25 mM HCO(3)(-). Purinergic agents potently stimulated short-circuit current (I(sc)) with an initial transient response declining within approximately 2 min to a sustained response. The potency sequence of ATP approximately UTP > ADP >> AMP suggested that the I(sc) response was mediated mainly by P2Y(2) receptors. Acetazolamide, an inhibitor of carbonic anhydrase, had little or no effect on baseline I(sc) or the transient response to ATP but abolished the sustained response to ATP. Similar results were obtained on sheets of native epithelium. In pH-stat experiments, the abluminal medium of cell cultures was bathed in HCO(3)(-)-CO(2) medium, and the pH of the unbuffered luminal medium was maintained at approximately 7.4 by addition of strong acid or base. ATP stimulated base secretion, and this was inhibited by acetazolamide. Furthermore, these changes in secretion of base were in good quantitative agreement with the I(sc) responses. When phenol red (an estrogen) was removed from the culture medium, ATP-dependent HCO(3)(-) secretion was markedly reduced but could be restored by treatment with estradiol. Estrogens also markedly increased ciliation of the cultures. These results suggest that the midcycle increase in the HCO(3)(-) concentration of oviductal liquid may be mediated by the effects of estradiol on purinergic pathways or on ATP secretion.

Phenol red in the culture medium strongly affects the susceptibility of human MCF-7 cells to roscovitine

Estrogens play an important role in the growth and terminal differentiation of the mammary gland. Prolonged exposure to estrogens seems to predispose women to breast cancer. It recently became evident that not only the intrinsic hormonal status but also external factors such as the occurrence of pharmaceuticals and chemicals with hormone activity in the environment may put women at greater risk of developing breast cancer. We focused on the interference of endocrine disruptors in breast cancer therapy. We observed that phenol red added to the culture medium strongly promoted the cell proliferation and cell cycle progression of human cells expressing the estrogen receptor, and affected their susceptibility to chemotherapy.

Extracellular environment as one mediator of blue light-induced mitochondrial suppression

OBJECTIVES

The current study tested the hypothesis that the extracellular environment mediates mitochondrial suppression of oral epithelial cells and fibroblasts by blue light.

METHODS

We exposed Balb fibroblasts (Balb), normal human epidermal keratinocytes (NHEK), and oral squamous carcinoma cells (OSC2) to blue light (30-120J/cm2) in different cell-culture media and in phosphate buffered saline (PBS). Mitochondrial activity (MTT method) was used to assess cellular response 72 h post-light exposure. Cell-culture media were replaced or supplemented before or after light exposure to assess the variables of exposure time and medium degradation as mediators of blue light-induced effects.

RESULTS

Mitochondrial activity of NHEK was not suppressed by exposure to blue light regardless of extracellular conditions. The mitochondrial activity of OSC2 and Balb cells was suppressed most when cells were exposed to light in cell-culture medium (versus PBS). Blue light suppressed mitochondrial activity more when irradiated medium remained in contact with the cells at least 1h, indicating a time-dependence of the medium effects. Neither a replacement nor a supplementation of medium components reduced blue light-induced mitochondrial suppression.

SIGNIFICANCE

Our results suggest that tissue environments influence cellular responses to blue light and that these environments should be considered when assessing any biological effects of blue light during the photopolymerization of restorative resins.

Expression of the lipid transfer protein Ace-AMP1 in transgenic wheat enhances antifungal activity and defense responses

To enhance fungal disease resistance, wheat plants (cv. Bobwhite) were engineered to constitutively express the potent antimicrobial protein Ace-AMP1 from Allium cepa, driven by a maize ubiquitin promoter along with its first intron. The bar gene was used for selection of putative transformants on medium containing phosphinothricin (PPT). Transgene inheritance, integration and stability of expression were confirmed over two generations by PCR, Southern, northern and western blot analyses, respectively. The levels of Ace-AMP1 in different transgenic lines correlated with the transcript levels of the transgene. Up to 50% increase in resistance to Blumeria graminis f. sp. tritici was detected in detached leaf assays. In ears of transgenic wheat inoculated with Neovossia indica, Ace-AMP1 intensified expression of defense-related genes. Elevated levels of salicylic acid and of transcripts of phenylalanine ammonia lyase (PAL), glucanase (PR2) and chitinase (PR3) in the transgenic plants indicated manifestation of systemic acquired resistance (SAR).

Antagonism of ATP responses at P2X receptor subtypes by the pH indicator dye, Phenol red

1 Many types of culture media contain a pH-sensitive dye. One commonly occurring dye, Phenol red sodium (Na(+)) salt, was tested for blocking activity at rat P2X(1-4) receptors (P2X(1-4)Rs) expressed in Xenopus oocytes. 2 Phenol red Na(+)-salt antagonised adenosine 5'-triphosphate (ATP) responses at P2X(1)R (IC(50), 3 microM) and, at higher concentrations, also blocked P2X(2)R and P2X(3)R. Phenol red Na(+)-salt, purified of lipophilic contaminants, blocked P2X(1)R and P2X(3)R by acting as an insurmountable antagonist. 3 Two lipophilic extracts of Phenol red antagonised ATP responses at P2XRs. Extract A was a potent antagonist at P2X(1)R (IC(50), 1.4 microM), whereas extract B was a potent antagonist at P2X(3)R (IC(50), 4.1 microM). A bisphenolic compound (RS151030) found in these extracts was a potent antagonist at P2X(1)R (IC(50), 0.3 microM) and at P2X(3)R (IC(50), 2.4 microM). 4 Phenolphthalein base was a potent irreversible antagonist at P2X(1)R (IC(50), 1 microM), whereas Phenolphthalein K(+)-salt was 25-fold less potent here. 5 Phenolphthalein base was a reversible antagonist of ATP responses at rat P2X(4)R (IC(50), 26 microM), whereas Phenolphthalein K(+)-salt was inactive. 6 Dimethyl sulphoxide (DMSO), used to dissolve lipophilic extracts, showed pharmacological activity by itself at rat P2X(1)R and P2X(4)R. 7 Thus, Phenol red and related compounds are antagonists at rat P2X(1)R, but are also active at other rat P2XRs. Phenolphthalein base is a newly identified, low potency antagonist of ATP responses at P2X(4)R. Culture media containing these red dyes should be used cautiously in future pharmacological studies of P2XRs. Also, wherever possible, the solvent DMSO should be used with caution.

A simple and rapid high-performance liquid chromatography method for determining furosemide, hydrochlorothiazide, and phenol red: applicability to intestinal permeability studies

A simple reversed-phase high-performance liquid chromatography (HPLC) method with ultraviolet detection at 280 nm was developed for simultaneous quantitation of furosemide and hydrochlorothiazide along with phenol red as a nonabsorbable marker for in situ permeability studies in anaesthetized rats. A jejunal segment of approximately 10 cm was isolated and cannulated in both ends for inlet and outlet solution. The perfusate was collected every 10 min, and samples were analyzed using the developed method. The mobile phase was acetonitrile-water-triethylamine-glacial acetic acid (41.5 + 57.4 + 0.1 + 0.9, adjusted to pH 5.6) at a flow rate of 1 mL/min; the run time was 9 min. The calibration graphs were linear for all 3 compounds (r > 0.999) across the concentration range of 7.93-125 microg/mL for phenol red and 6.25-100 microg/mL for hydrochlorothiazide and furosemide. The limits of quantitation were 7.2, 8.9, and 6.8 microg/mL for furosemide, hydrochlorothiazide, and phenol red, respectively. The coefficients of variation for intraassay and interassay precision were less than or equal to 7.6%, and the accuracy was between 93.2-103.4%. Using the single pass intestinal perfusion technique and the suggested HPLC method for sample analysis, mean values of 0.25 x 10(-4) (+/-0.16) cm/s and 0.22 x 10(-4) (+/-0.13) cm/s were obtained for furosemide and hydrochlorothiazide, respectively.

Phenol red reduces ROSC mediated cell cycle arrest and apoptosis in human MCF-7 cells

We reported recently that roscovitine (ROSC), a selective cyclin-dependent kinase (CDK) inhibitor, arrested human MCF-7 breast cancer cells in G2 phase of the cell cycle and concomitantly induced apoptosis. On the other hand, ROSC-induced G1 arrest observed by another group has not been accompanied by apoptosis. Therefore, we decided to prove to which extent components of tissue culture media could affect the primary action of ROSC. For this purpose we compared the efficacy of the ROSC treatment on MCF-7 cells cultivated in medium with and without phenol red. The kinetics of MCF-7 cell proliferation strongly depended on the presence of phenol red that has been recognized previously as a weak estrogen. Exposure of MCF-7 cells cultivated in phenol red-deprived medium to ROSC resulted in a strong G2 arrest and apoptosis. However, the anti-proliferative and pro-apoptotic action of ROSC was strongly diminished in cells maintained in medium containing phenol red. The ratio of the G2 cell population after 12 h ROSC was reduced by approximately 20% in the latter and correlated with the lack of CDK2 inactivation. Moreover, the kinetics of ROSC-induced apoptosis was delayed in the presence of phenol red. These results clearly evidence that the efficacy of the therapy of ER-positive breast cancers by CDK inhibitors is diminished in the presence of estrogen-mimicking compounds and indicate that phytoestrogens and xenoestrogens could interfere with the therapy. Therefore, the exposure of cancer patients to the estrogen mimics should be avoided at least during chemotherapy by CDK inhibitors.

Cytoarchitecture modifications of the human uterine endocervical mucosa in long-term three-dimensional organotypic culture

We assayed the effects of phenol red (pr), estrogen (Es), and progesterone (Pg) in three-dimensional organotypic cultures of human uterine endocervix. Small intact fragments deposited on sponges submerged in DMEM with 10% fetal bovine serum were cultured in three different conditions: with pr (DMEM(pr+)), without pr (DMEM(pr-)), and without pr but with the addition of physiological concentrations of Es and Pg [DMEM(pr-)(Es+Pg)]. Cell viability and cellular responses were assayed after 4, 10, and 21 days using immunohistochemistry for the expression and distribution of the following markers: mucins and mucopolysaccharides (PAS staining), pan-cytokeratins (AE1/AE3), CK19, p63, Ki-67, vimentin, estrogen receptor-alpha (ER-alpha), and progesterone receptor (PR). The fragments cultivated in DMEM(pr+) showed a cuboidal, poorly differentiated epithelial phenotype and signs of stroma degeneration. In DMEM(pr-), both tissue architecture and cellular heterogeneity were much better preserved: epithelial cells showed a more columnar shape, and stroma was very well conserved, maintaining cell density. The addition of Es and Pg further improved the histology and physiology of the fragments: in DMEM(pr-)(Es+Pg), epithelial cells retained a columnar shape, secreted mucins, and formed areas of squamous hyperplasia.

Phenolsulfonphthalein transport by potential-sensitive urate transport system

The purpose of this study was to elucidate the transporter-mediated secretion systems for phenolsulfonphthalein in brush-border membranes. In human and rat renal brush-border membranes, a potential-sensitive transport system has been shown to be involved in the efflux of organic anions. The uptake of phenolsulfonphthalein into rat renal brush-border membrane vesicles was stimulated by an inside-positive membrane potential. This potential-sensitive uptake of phenolsulfonphthalein was inhibited by probenecid, pyrazinoate and urate. p-Aminohippurate had no effect on the potential-sensitive uptake of phenolsulfonphthalein. Moreover, urate competitively inhibited the uptake of phenolsulfonphthalein. On the other hand, the uptake of phenolsulfonphthalein was slightly increased in the presence of an outward Cl- gradient. These results suggest that phenolsulfonphthalein has high affinity for the potential-sensitive urate transport system but has low affinity for an anion exchanger.

Oogenesis in cultures derived from adult human ovaries

Ten years ago, we reported that in adult human females the ovarian surface epithelium (OSE) is a source of germ cells. Recently, we also demonstrated that new primary follicles are formed by assembly of oocytes with nests of primitive granulosa cells in the ovarian cortex. The components of the new primary follicles, primitive granulosa and germ cells, differentiated sequentially from the OSE, which arises from cytokeratin positive mesenchymal progenitor cells residing in the ovarian tunica albuginea. In the present study, we investigated the possibility that the oocytes and granulosa cells may differentiate in cultures derived from adult human ovaries. Cells were scrapped from the surface of ovaries and cultured for 5 to 6 days, in the presence or absence of estrogenic stimuli [phenol red (PhR)]. The OSE cells cultured in the medium without PhR differentiated into small (15 micron) cells of granulosa phenotype, and epithelial, neural, and mesenchymal type cells. In contrast, OSE cells cultured in the presence of PhR differentiated directly into large (180 micron) cells of the oocyte phenotype. Such cells exhibited germinal vesicle breakdown, expulsion of the polar body, and surface expression of zona pellucida proteins, i.e. characteristics of secondary oocytes. These in vitro studies confirm our in vivo observations that in adult human ovaries, the OSE is a bipotent source of oocytes and granulosa cells. Development of numerous mature oocytes from adult ovarian stem cells in vitro offers new strategies for the egg preservation, IVF utilization, and treatment of female infertility. In addition, other clinical applications aiming to utilize stem cells, and basic stem cell research as well, may employ totipotent embryonic stem cells developing from fertilized oocytes.

Ion transport across model lipid membranes containing light-harvesting complex II: an effect of light

The effect of light on proton transport across lipid membranes of small unilamellar liposomes containing incorporated major light-harvesting pigment-protein complex of Photosystem II (LHCII) has been studied with the application of pH-sensitive dyes entrapped inside vesicles. Proton permeability coefficient for LHCII-modified membranes was found to be about twice as high as in the case of the control pure lipid vesicles. Illumination of the samples with light absorbed by the LHCII-bound photosynthetic pigments considerably affects the kinetics of proton transport: it increases the rate and decreases the steady-state level of proton gradient across the membranes. The effect was interpreted in terms of heat-induced conformational changes of LHCII molecular structures that affect proton buffering capacity of this protein. Both the control and the LHCII-modified lipid membranes have been found to be practically impermeable to Ca(++) ions, as demonstrated by fluorescence of liposome-entrapped calcium-sensitive probe calcium crimson. The slight differences in the proton transport across the LHCII-containing membranes under the presence of Ca(++) suggest calcium binding to this antenna protein.

Inhibition of islet amyloid polypeptide fibril formation: a potential role for heteroaromatic interactions

The formation of amyloid fibril is associated with major human diseases, including Alzheimer's disease, prion diseases, and type 2 diabetes. Methods for efficient inhibition of amyloid fibril formation are therefore highly clinically important. A principal approach for the inhibition of amyloid formation is based on the use of modified molecular recognition elements. Here, we demonstrate efficient inhibition of amyloid formation of the type 2 diabetes-related human islet amyloid polypeptide (hIAPP) by a modified aromatic peptide fragment and a small aromatic polyphenol molecule. A molecular recognition assay using peptide array analysis suggested that molecular recognition between hIAPP and its core amyloidogenic module is mediated by aromatic rather than hydrophobic interactions. To study the possible effect of aromatic interactions on inhibition of hIAPP fibril formation, we have used peptide and small molecule inhibitors. The addition of a nonamyloidogenic peptide analogue of the core module NFGAILSS, in which phenylalanine was substituted with tyrosine (NYGAILSS), resulted in substantial inhibition of fibril formation by hIAPP. The inhibition was significantly stronger than the one achieved using a beta-sheet breaker-conjugated peptide NFGAILPP. On the basis of the molecular arrangement of the tyrosine-phenylalanine interaction, we suggest that the inhibition stems from the geometrical constrains of the heteroaromatic benzene-phenol interaction. In line with this notion, we demonstrate remarkable inhibition of hIAPP fibril formation and cytotoxicity toward pancreatic beta-cells by a small polyphenol molecule, the nontoxic phenol red compound. Taken together, our results provide further experimental support for the potential role of aromatic interactions in amyloid formation and establish a novel approach for its inhibition.

Increasing Dialysate Flow and Dialyzer Mass Transfer Area Coefficient to Increase the Clearance of Protein-bound Solutes

Clinical hemodialysis systems achieve high single pass extraction of small solutes that are not bound to plasma proteins. But they clear protein-bound solutes much less effectively. This study examines the extent to which clearance of a protein-bound test solute is improved by increasing the dialyzer mass transfer area coefficient (KoA) and the dialysate flow rate (Qd). A reservoir containing test solutes and artificial plasma with albumin concentration approximately 4 g/dl was dialyzed with a standard clinical dialysate delivery system. The clearance of phenol red (ClPR) was compared with the clearances of urea and creatinine at a plasma flow rate (Qp) of 200 ml/min with varying values of KoA and Qd. ClPR increased from 11 +/- 2 ml/min to 23 +/- 2 ml/min when KoA for phenol red, KoAPR, was increased from 238 to 640 ml/min and Qd was increased from 286 +/- 6 ml/min to 734 +/- 9 ml/min. Increasing either KoAPR or Qd alone had lesser effects. Clearance values for phenol red were much lower than clearance values for the unbound solutes urea and creatinine, which ranged from 150 to 200 ml/min and were less affected by varying KoA and Qd. A mathematical model was developed to predict ClPR from values of Qp, Qd, the fraction of phenol red bound to albumin (94% +/- 1%) and KoAPR. The model accurately predicts the pattern of measured results and shows further that ClPR can be made to approach Qp only by very large increases in both KoAPR and Qd.

Effects of culture conditions on taurine uptake by various variants of human endometrial carcinoma cells in culture

The general properties of the taurine uptake in human endometrial tumoral Ishikawa cells were similar to those usually found in other tissues. Uptake was notably affected by the oxygen pressure, being higher at the physiological pO(2) of the endometrium (40 mm Hg, equivalent to 5% O(2)) compared to that used under standard experimental culture conditions (160 mm Hg or 20% O(2)). Uptake of taurine was also density-dependent in Ishikawa cells and was significantly decreased at confluence. Uptake regulation by PKC driven phosphorylation occurs only in growing cells and not in resting cells. The taurine uptake of three Ishikawa cell lines was very different. The taurine uptake of one of the cell lines was affected by estradiol, probably through a non-genomic pathway, whereas tamoxifen had no effect in all cell lines.

First evidence of catalytic mediation by phenolic compounds in the laccase-induced oxidation of lignin models

The sulfonephthalein indicator, phenol red, exhibits an unusually slow rate of oxidation by laccase from Poliporus pinsitus, in spite of the fact that it is a phenol and therefore a natural substrate for this phenoloxidase enzyme. Nevertheless, after prolonged exposure to laccase (24 h) phenol red is oxidized by more than 90%. We found that phenol red, which can be oxidatively converted into a resonance-stabilized phenoxy radical, performs as a mediator in the laccase-catalyzed oxidation of a nonphenolic substrate (4-methoxybenzyl alcohol) and also of a hindered phenol (2,4,6-tri-tert-butylphenol). In particular, phenol red was found to be at least 10 times more efficient than 3-hydroxyanthranilate (a reported natural phenolic mediator of laccase) in the oxidation of 4-methoxybenzyl alcohol. Other phenols, which do not bear structural analogies to phenol red, underwent rapid degradation and did not perform as laccase mediators. On the other hand, several variously substituted sulfonephthaleins, of different pK2 values, mediated the laccase catalysis, the most efficient being dichlorophenol red, which has the lowest pK2 of the series. The mediating efficiency of phenol red and dichlorophenol red was found to be pH dependent, as was their oxidation Ep value (determined by cyclic voltammetry). We argue that the relative abundance of the phenoxy anion, which is easier to oxidize than the protonated phenol, may be one of the factors determining the efficiency of a phenolic mediator, together with its ability to form relatively stable oxidized intermediates that react with the desired substrate before being depleted in undesired routes.

Membrane damage to bacteria caused by single and combined biocides

AIMS

To examine the effect on the leakage of low molecular weight cytoplasmic constituents from Staphylococcus aureus using phenolics singly and in combination, and to see if the observations could be modelled using a non-linear dose response.

METHODS AND RESULTS

The rate of potassium, phosphate and adenosine triphosphate leakage was examined in the presence of chlorocresol and m-cresol. Individually, leakage was observed only at long contact times or high concentrations. Combined at these ineffective concentrations, the cytoplasmic pool of all constituents studied was released within minutes. Both chlorocresol and m-cresol were shown to have non-linear dose responses. A rate model for the combinations, which takes account of these non-linear responses, accurately predicted the observations.

CONCLUSIONS

Antimicrobials, which when used alone exhibit a non-linear dose response, will also give a non-linear dose response in combination. The simple linear-additive model ignores the concept of the dilution coefficient and will always describe the phenomenon of synergy for combinations where one or more of the components has a dilution coefficient greater than one. This has been borne out by examination of the purported prime lesion of chlorocresol and m-cresol, alone and in combination.

SIGNIFICANCE AND IMPACT OF THE STUDY

Studies aimed at producing synergistic mixtures of antimicrobials, which ignore the non-linear additive effect, may waste valuable research effort looking for a physiological explanation for an apparent synergy, where none, in-fact, exists. Patents granted on the basis of analyses using the linear-additive model for combinations of compounds with non-linear dose responses may no longer be supportable.

Effects of phenol red on CFU-f differentiation and formation

Osteoblastic induction is commonly studied using the colony-forming unit-fibroblastic (CFU-f) assay, in which bone marrow stromal cells (BMC) are grown in a tissue culture environment permissive for osteoblastic differentiation (DMEM containing dexamethasone, ascorbic acid and beta-glycerophosphate). These cells form colonies, which express alkaline phosphatase, and form a collagenous matrix that becomes calcified. However, these same cells originate in the bone marrow where under normal circumstances they do not proliferate or differentiate despite being subjected to many of the same growth factors and hormones present within the tissue culture environment. We show here that phenol red, present within tissue culture medium as a pH indicator, may itself be a factor that permits osteoblastic recruitment. BMC cultured in the presence of the bone anabolic agents PGE2, PGA2, or bFGF, but in the absence of phenol red, failed to respond to these agents in terms of total or osteoblastic colony number. This effect was dose dependent, with low (2.5 mg/l) and high (15-20 mg/l) doses of phenol red being nonpermissive for the stimulatory effects of PGE2 whereas doses of 5-10 mg/l were permissive. Furthermore, the effects observed in the absence of phenol red could not be abrogated by the addition of 17beta-estradiol indicating that these effects cannot be attributed to estrogenic impurities within the phenol red preparation. This indicates that phenol red itself can affect the differentiation of BMC by a mechanism not previously described.

Mucosal permeability regulates receptor binding of luminal epidermal growth factor in the adult rat intestine

Epidermal growth factor (EGF) stimulates repair in the damaged intestine, but its role in the normal intestine is not clear. Because EGF receptors are found on the basolateral surface but not the luminal surface, we hypothesized that mucosal permeability regulates EGF binding. Adult male rats were divided into 3 groups, one that was fed normal chow (the control), one that was starved for 4 days, and one that was given methotrexate (MTX) intragastrically (10 mg/kg/day for 3 days). The rats were sacrificed and everted sacks of the jejunum were made and incubated in EGF solution. Western blot analysis of mucosal homogenates showed that the amount of phosphotyrosyl EGF receptor in the starved and MTX-treated groups was, respectively, about 1.5 times and 2 times that in the control group. The mucosal permeability in the starved and MTX treated groups also increased and varied directly with the amount of phosphotyrosyl EGF receptor. These results suggest that in the adult rat intestine, luminal EGF may play a role only under tissue damage, where enhanced permeability permits the EGF to pass through the mucosa and bind to its receptor on the basolateral membrane.

Expression and localization of estrogen receptor-alpha protein in normal and abnormal term placentae and stimulation of trophoblast differentiation by estradiol

Estrogens play an important role in the regulation of placental function, and 17-beta-estradiol (E2) production rises eighty fold during human pregnancy. Although term placenta has been found to specifically bind estrogens, cellular localization of estrogen receptor alpha (ER-alpha) in trophoblast remains unclear. We used western blot analysis and immunohistochemistry with h-151 and ID5 monoclonal antibodies to determine the expression and cellular localization of ER-alpha protein in human placentae and cultured trophoblast cells. Western blot analysis revealed a ~65 kDa ER-alpha band in MCF-7 breast carcinoma cells (positive control). A similar band was detected in five normal term placentae exhibiting strong expression of Thy-1 differentiation protein in the villous core. However, five other term placentae, which exhibited low or no Thy-1 expression (abnormal placentae), exhibited virtually no ER-alpha expression. In normal placentae, nuclear ER-alpha expression was confined to villous cytotrophoblast cells (CT), but syncytiotrophoblast (ST) and extravillous trophoblast cells were unstained. In abnormal placentae no CT expressing ER-alpha were detected. Normal and abnormal placentae also showed ER-alpha expression in villous vascular pericytes and amniotic (but not villous) fibroblasts; no staining was detected in amniotic epithelial cells or decidual cells. All cultured trophoblast cells derived from the same normal and abnormal placentae showed distinct ER-alpha expression in western blots, and the ER-alpha expression was confined to the differentiating CT, but not to the mature ST. Trophoblast cells from six additional placentae were cultured in normal medium with phenol red (a weak estrogen) as above (PhR+), or plated in phenol red-free medium (PhR-) without or with mid-pregnancy levels of E2 (20 nM). Culture in PhR- medium without E2 caused retardation of syncytium formation and PhR-medium with E2 caused acceleration of syncytium formation compared to cultures in PhR+ medium. These data indicate that the considerable increase in estrogen production during pregnancy may play a role, via the ER-alpha, in the stimulation of CT differentiation and promote function in normal placentae. This mechanism, however, may not operate in abnormal placentae, which show a lack of ER-alpha expression.

Phenol red inhibits uptake of phosphate by the everted gut sacs of mice

Uptake of phosphate by the everted intestinal sacs of mice was measured at various concentrations of this anion in the incubation medium. Phenol red when added to the serosal side was able to inhibit the uptake of phosphate significantly, while uptake of glucose or proline was unaffected. When para amino hippuric acid was present along with phenol red in the serosal compartment, the inhibition exerted by the dye on phosphate uptake was significantly less. These findings suggest that entry of phenol red into gut tissue from the serosal side interferes with the mucosal uptake of phosphate by the everted intestinal sacs of mice.

Improving laccase production by employing different lignocellulosic wastes in submerged cultures of Trametes versicolor

Laccase production by the white-rot fungus Trametes versicolor (CBS100.29) grown in submerged cultures was studied. Addition of different insoluble lignocellulosic materials into the culture medium in order to enhance laccase production was investigated. The lignocellulosic materials were grape seeds, grape stalks and barley bran, selected because of their availability and low cost, since they are agro-industrial wastes abundant in most countries. Barley bran gave the highest activities, a maximum value of 639U/l, which was 10 times the value attained in the cultures without lignocellulosics addition. The decolourisation of a model dye, Phenol Red, by the ligninolytic fluids obtained in the above-mentioned cultures was investigated. Grape stalk and barley bran cultures showed the highest ability to decolourise the dye, attaining a percentage of decolourisation of around 60% in 72 h.

Effect of phenol red and steroid hormones on cystic fibrosis transmembrane conductance regulator in mouse endometrial epithelial cells

Previous studies have demonstrated that cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-mediated Cl(-)channel found in most epithelia including reproductive tract, could be regulated by various culture conditions. The present study further investigated the effect of phenol red, a pH indicator widely used in growth medium, and steroid hormones, present in the supplement fetal bovine serum (FBS), on primary cultured endometrial epithelial cells by monitoring ion channel activities using the short-circuit current technique. When compared to the results obtained with normal medium supplemented with regular FBS, the forskolin-stimulated I(SC), presumably mediated by CFTR, obtained in phenol red-free medium was significantly reduced, from 16.95+/-1.53 microA/cm(2)(control) to 9.72+/-0.89 microA/cm(2)(medium without phenol red, P< 0.05). The forskolin-activated I(SC)was further attenuated to 5.29+/-0.46 microA/cm(2)in the phenol red-free medium when supplemented with charcoal/ dextran-treated FBS where steroid hormones were removed. Our data suggest that phenol red and steroid hormones present in culture medium and FBS supplement, respectively, may somehow upregulate CFTR expression in vitro. Our study demonstrates the need for carefully choosing the culture media and supplements due to the effect of steroid hormones.

Evaluation of the activity and localization of 15-lipoxygenase-1 after introduction into human colorectal carcinoma Caco-2 cells

In human colorectal carcinoma Caco-2 cells, sodium butyrate (NaBT) induces the expression of the reticulocyte, 15-lipoxygenase-1 (15-LO-1) and causes these cells to undergo differentiation and apoptosis. 15-LO-1 is also expressed in human colorectal epithelium with a significant higher expression observed in colorectal tumors. In this study, we have prepared stable Caco-2 cells that expressed 15-LO-1 under control of an inducible promoter. These cells provide a model system to study regulation of 15-LO-1 activity in colorectal cells without the interfering presence of NaBT and are useful to study the biological function of 15-LO-1. The expressed 15-LO-1 was highly active as measured in cell lysates, but we were unable to detect metabolism in intact cells. The addition of calcium to the media for the Caco-2 cells was required for 15-LO-1 to translocate from the cytosol to the membrane which is frequently a requirement for lipoxygenase activity. Despite the addition of calcium and translocation, little lipoxygenase activity was detected with intact cells. However, after removal of phenol red, a common constituent of cell culture media, we were able to detect 15-LO-1 activity in the transfected Caco-2 cultured cells. Thus the presence of calcium and the absence of antioxidants present in commonly used culture media are required for expressed 15-LO-1 to be catalytically active and to permit an examination of its biological effects.

Differential responsiveness of prostatic acid phosphatase and prostate-specific antigen mRNA to androgen in prostate cancer cells

Androgens regulate the expression of both human prostatic acid phosphatase (PAcP) and prostate-specific antigen (PSA), two major prostate epithelium-specific differentiation antigens. Due to the important role of these two enzymes as prostate epithelium differentiation markers, we investigated their regulation of expression at the mRNA level in LNCaP human prostate carcinoma cells. Interestingly, phenol red, a pH indicator in the culture medium, promoted cell growth. To eliminate this non-specific effect, a phenol red-free, steroid-reduced medium was utilized. When high-density cells were grown in that medium, 5alpha-dihydrotestosterone (DHT) suppressed PAcP but stimulated PSA. However, tumor promoter phorbol ester 12-o-tetradecanoyl phorbol-13-acetate (TPA) functioned as a potent inhibitor of both PAcP and PSA expression. Prolonged treatment with DHT as well as TPA resulted in a similar down-regulation of protein kinase C and cellular PAcP activities. Thus, the levels of PAcP and PSA mRNA are differentially regulated by androgens in LNCaP cells.

The organ-maintained human sebaceous gland

In the absence of epidermal growth factor (EGF) and phenol red in the maintenance medium, human sebaceous glands apparently retain in vivo rates of cell division and lipogenesis over 7 days and also retain in situ morphology. This is reversible on the re-addition of 10 ng/ml EGF and 10 mg/ml phenol red. The addition of 600 pM 17 beta-oestradiol results in a significant fall in the rate of lipogenesis over 7 days' maintenance, without affecting the rate of cell division. This effect is apparently due to abnormal differentiation of newly formed sebocytes. Neither 1 nM testosterone nor 1 nM dihydrotestosterone has any effect on rates of cell division or lipogenesis over 7 days. 1 microM 13-cis-retinoic acid causes a significant reduction in the rate of lipogenesis over 7 days.

Estrogen mitogenic action. III. is phenol red a "red herring"?

The reported estrogenic action of phenol red and/or its lipophilic contaminants has led to the widespread use of indicator-free culture medium to conduct endocrine studies in vitro. Because we have recently developed methods to measure large-magnitude estrogen effects in the tissue culture medium containing phenol red, we concluded that the indicator issue required further evaluation. To do this, we selected nine estrogen receptor positive (ER+) cell lines representing four target tissues and three species. We investigated phenol red using five different experimental protocols. First, 17beta-estradiol (E2) responsive growth of all nine ER+ cells lines was compared in the medium with and without the indicator. Second, using representative lines we asked if phenol red was mitogenic in the indicator-free medium. The dose-response effects of phenol red were compared directly to those of E2. Third, we asked if tamoxifen-inhibited growth equally in phenol red-containing and indicator-free medium. This study was based on a report indicating that antiestrogen effects should be seen only in phenol red-containing medium. Fourth, we asked if phenol red displaced the binding of 3H-E2 using ERK intact human breast cancer cells. Fifth, we compared E2 and phenol red as inducers of the progesterone receptor using a human breast cancer cell line. All the experiments presented in this report support the conclusion that the concentration of phenol red contaminants in a standard culture medium available today is not sufficient to cause estrogenic effects. In brief, our studies indicate that the real issue of how to demonstrate estrogenic effects in culture resides elsewhere than phenol red. We have found that the demonstration of sex steroid hormone-mitogenic effects in culture depends upon conditions that maximize the effects of a serum-borne inhibitor(s). When the effects of the inhibitor are optimized, the presence or absence of phenol red makes no everyday difference to the demonstration of estrogen mitogenic effects with several target cell types from diverse species.

In-vivo and in-vitro evidence of a carrier-mediated efflux transport system for oestrone-3-sulphate across the blood-cerebrospinal fluid barrier

The efflux transport of oestrone-3-sulphate, a steroid hormone sulphate, across the blood-cerebrospinal fluid barrier has been examined following its intracerebroventricular administration. [3H]Oestrone-3-sulphate was eliminated from cerebrospinal fluid (CSF) with an apparent efflux clearance of 205 microL min(-1) per rat. There was 25% of unmetabolized [3H]oestrone-3-sulphate in the plasma 5 min after intracerebroventricular administration, indicating that at least a part of [3H]oestrone-3-sulphate is transported from CSF to the circulating blood across the blood-CSF barrier. This efflux transport was inhibited by co-administration of excess oestrone-3-sulphate (25 mM 10 microL = 0.25 micromol) into rat cerebral ventricle. To characterize the oestrone-3-sulphate transport process, an in-vitro uptake experiment was performed using isolated rat choroid plexus. Oestrone-3-sulphate uptake by isolated rat choroid plexus was found to be a saturable process with a Michaelis-Menten constant (Km) of 18.1 +/- 6.3 microM, and a maximum uptake rate (Vmax) of 48.0 +/- 15.1 pmol min(-1) microL(-1) of tissue. The oestrone-3-sulphate transport process was temperature dependent and was inhibited by metabolic inhibitors such as 2,4-dinitrophenol and rotenone, suggesting an energy dependence. This uptake process was also inhibited by steroid hormone sulphates (1 mM dehydroepiandrosterone sulphate and 1 mM oestrone sulphate), bile acids (1 mM taurocholic acid and 1 mM cholic acid) and organic anions (1 mM sulphobromophthalein and 1 mM phenolsulphonphthalein), whereas 1 mM p-aminohippuric acid, 1 mM p-nitrophenol sulphate, 0.1 mM methotrexate and the cardiac glycoside, 2.5 microM digoxin, had little effect. In conclusion, these results provide evidence that oestrone-3-sulphate is transported from CSF to the circulating blood across the blood-CSF barrier via a carrier-mediated efflux transport system.

The organ maintained human sebaceous gland

<i>Objective:</i> Antiphospholipid syndrome (APS) or Hughes syndrome is a frequently seen condition in Kuwait that is characterised by the presence of significant titres of a variety of antiphospholipid antibodies (aPL). The main clinical features of this syndrome include thrombosis (both venous and arterial), recurrent fetal wastage and thrombocytopenia. The aim of the present study was to find out the antibodies with a high predictive value for the diagnosis of APS. <i>Methodology:</i> The study included a total of 38 subjects. Nine of them were patients with proven primary APS, 10 with secondary APS and 19 were patients (controls) with weak clinical evidence of APS. After a complete clinical examination and routine investigations, the following categories of aPL were estimated by standard laboratory techniques: anticardiolipin antibodies of IgG and IgM isotypes (GPL and MPL, respectively), anti-β₂-glycoprotein-I antibodies (anti-β₂-GPI) of IgG and IgM isotypes and activated partial thromboplastin time as a surrogate for lupus anticoagulant (LAC). The tests were considered positive if the titres were more than a standard cut-off value provided by the manufacturer of the kits, and in one instance, the normal range was established in our laboratory (LAC). <i>Results:</i> The highest sensitivity (78.9%) and diagnostic accuracy (71.1%) were obtained by the estimation of GPL. However, excellent specificity (100%) and positive predictive value (100%) with almost as good a diagnostic accuracy (68.4%) were also obtained with anti-β₂-GPI of IgG isotype. All the other tests performed poorly when compared with these two. There was no difference in the performance of these tests between primary and secondary APS. <i>Conclusion:</i> Of the various aPL estimated, GPL and anti-β₂-GPI of IgG isotype were statistically sensitive and specific investigations for confirming the diagnosis of APS.

Inhibition of human aldehyde reductase by drugs for testing the function of liver and kidney

Drugs for testing the function of liver and kidney (sulfobromophthalein, phenolsulfonphthalein, indigo carmine and indocyanine green) and other organic anions (rose bengal and haematin) were found to potently inhibit human liver aldehyde reductase that is involved in the detoxification of 3-deoxyglucosone and methylglyoxal, reactive intermediates, during the formation of advanced glycation end products. The inhibition patterns by the compounds were non-competitive with respect to both coenzyme (NADPH) and substrate (D-glucuronate). The kinetics of the inhibition by a mixture of the 2 inhibitors suggests that all the inhibitory compounds bind to overlapping sites on the enzyme. The binding of rose bengal, sulfobromophthalein and phenylsulfonphthalein to the free enzyme was detected by ultrafiltration assay. However, in the reverse reaction, the enzyme was inhibited competitively with respect to the alcohol substrate by rose bengal, haematin, phenolsulfonphthalein, sulfobromophthalein, indigo carmine and indocyanine green, which showed Ki values of 0.1, 1, 3, 4, 4 and 10 microM, respectively. The results suggest that these potent inhibitors bind weakly to the free enzyme and tightly to the enzyme-NADP binary complex.

Optimization of treatment conditions for studying the anticancer effects of retinoids using pancreatic adenocarcinoma as a model

Retinoids are natural differentiation-inducing compounds that are promising as anticancer agents. Cancer cell lines are valuable in the investigation of the potential of retinoids for the treatment of specific cancers. However, using different treatment conditions but the same cell lines, investigators have produced markedly contradictory results for the effectiveness of retinoids. The present study examined different factors in the treatment conditions that may have masked or interfered with the effects of retinoids and, thereby, resulted in this conflict. Our studies revealed that the effects of retinoids on cancer cell proliferation were influenced by serum, the choice of vehicle (DMSO vs ethanol) and its concentration, phenol red, the degree of cellular confluence, and the method of assessing proliferation (cell number or [3H]thymidine uptake vs the MTT assay). Optimized conditions were the use of serum-free, ethanol-free, and phenol red-free media, investigating cells in the log phase of growth, using </=0.01% DMSO as the vehicle, and monitoring proliferation by cell number or [3H]thymidine incorporation into DNA measured after TCA precipitation. Using these conditions, retinoids were found to exhibit potent antiproliferative effects in pancreatic cancer cells with a variety of degrees of differentiation, even in cell lines previously documented as being retinoid resistant. Retinoids also induced morphological changes and cellular death that may indicate terminal differentiation and apoptosis.

Bisphenols that stimulate cells to release alkali metal cations: a structure-activity study

The laxative action of phenolphthalein (5) is believed to result from induction of potassium and water efflux from the colon epithelium. In cultured cells, K+ efflux is promoted by 5 and by a contaminant (1) present in commercial phenol red. Six compounds with chemical structures related to those of 5 and 1 were tested for ability to induce the release of 86Rb from COS-7 cells preloaded with this isotope: 4,4'-(9-fluorenylidene)diphenol (2), 4, 4'-(9-fluorenylidene)dianiline, 4, 4'-(9-fluorenylidene)bisphenoxyethanol, 1,1'-bi-2-naphthol, 4, 4'-biphenol, and bis(4-hydroxyphenyl)methane. With one exception these compounds were all inactive at a concentration of 10 microM. However, 2 caused profound 86Rb efflux at concentrations as low as 100 nM. Concentrations of 5 1-2 orders of magnitude higher were needed to achieve similar levels of activity. The three compounds known to be active in this experimental system share a common feature that is absent in all the inactive compounds: a five-membered ring structure, one of whose carbon atoms is disubstituted with p-hydroxyphenyl residues. Because 2 and 5 are readily available, comparative studies on the mechanism of action of these biphenols at the cellular level can now be undertaken.

Self-association properties of monomeric insulin analogs under formulation conditions

PURPOSE

The purpose of the current study was to investigate the effects of two important excipients, zinc and m-cresol, on the self-association properties of a series of monomeric insulin analogs. In this way, the effects on formulation behavior of individual amino acid substitutions in the C-terminal region of the insulin B-chain could be compared.

METHODS

The self-association of ten insulin analogs was monitored by equilibrium and velocity analytical ultracentrifugation under three different conditions: (i) in neutral buffer alone; (ii) in neutral buffer containing zinc ion; and (iii) in neutral buffer containing both zinc ion and phenolic preservative (a typical condition for insulin formulations). The self-association properties of these analogs were compared to those of human insulin and the rapid-acting insulin analog Lys(B28)Pro(B29)-human insulin.

RESULTS

The analogs in the current study exhibited a wide range of association properties when examined in neutral buffer alone or in neutral buffer containing zinc ion. However, all of these analogs had association properties similar to human insulin in the presence of both zinc and m-cresol. Under these formulation conditions each analog had an apparent sedimentation coefficient of s* = 2.9-3.1 S, which corresponds to the insulin hexamer.

CONCLUSIONS

Analogs with changes in the B27-B29 region of human insulin form soluble hexamers in the presence of both zinc and m-cresol, and m-cresol binding overrides the otherwise destabilizing effects of these mutations on self assembly.

Involvement of endotoxins or tumor necrosis factor-alpha in macrophage-mediated oxidation of low density lipoprotein

Oxidation of low-density lipoprotein (LDL) can be mediated in vitro by cultured cells, including macrophages. This cellular oxidation is dependent on the production of free thiols by the cells in the presence of transition metal ions. We now report that the production of thiols by macrophages is greatly enhanced when cells are cultured with lipopolysaccharide (LPS) or tumor necrosis factor-alpha (TNF-alpha). Oxidation of LDL by macrophages is markedly augmented by pre-treatment of the cells with LPS or TNF-alpha. The results suggest that activation by endotoxins or TNF-alpha is a necessary step for macrophages to mediate oxidation of LDL.

Properties of overlapping EREs: synergistic activation of transcription and cooperative binding of ER

We have designed a novel estrogen-responsive unit, overERE, which consists of two overlapping ERE separated by 5 bp (center-to-center). In gel retardation assays, this sequence forms a low-mobility complex that migrates like an estrogen receptor tetramer. The receptor-overERE complex was specific and was supershifted by anti-ER H222 antibodies. Dose response studies showed that the formation of the receptor tetramer-overERE complex was cooperative. Truncated receptors were used to assess the contribution of the receptor domains. Deletion of the E domain of the ER prevented the formation of an ER-tetramer complex, which reflects a novel function of this receptor domain. In transfection experiments, 17-beta-estradiol activated transcription from an overERE-containing promoter 4-6 times better than from an ERE-containing promoter. This synergistic effect was observed using either the natural hormone (17-beta-estradiol) or xenoestrogens (phenol red, chlordane). We conclude that two overlapping estrogen-responsive elements can elicit synergistic induction of transcription.

[Changes of thromboxane A2 receptors and their mRNA expression and effects of their antagonist phenol red in the lung of acute lung injury of rats]

OBJECTIVE

To investigate the changes of thromboxane A2 receptors and the influence of their antagonist phenol red, and to study in molecular level the mechanism of action of thromboxane A2 in acute lung injury.

METHODS

Acute lung injury model of rats was produced by oleic acid, and phenol red (5 mg/kg, 50 mg/kg) was injected via vein 5 minutes before oleic acid injection. Changes of thromboxane A2 receptors and their mRNA expression in the lung were determined at 6 hours after oleic acid injection.

RESULTS

Down-regulation of thromboxane A2 receptors were observed, but their mRNA transcription increased significantly in the lung after oleic acid injection. The injection of phenol red before oleic acid could induce down-regulation of thromboxane A2 receptors and abolish the increase of their mRNA transcription after oleic acid injection. Phenol red could reduce LBI, RLW and improve PaO2. Histological examination of lung tissues demonstrated that the degree of lung injury had been reduced significantly.

CONCLUSION

Thromboxane A2 plays an important role plays in pathological processes of acute lung injury. Phenol red in vivo could effectively reduce severity of acute lung injury by blocking thromboxane A2 receptors and regulating the expression of thromboxane A2 receptors.

Estrogen affects development of alveolar structures in whole-organ culture of mouse mammary glands

In order to determine if estrogen affects lobulo-alveolar development, and to determine if whole organ culture of mouse mammary glands is an appropriate model of estrogen effects on mammary development, mouse mammary glands were cultured in the presence or absence of phenol red and estrogen. Lobulo-alveolar development did not occur in vitro when phenol red was eliminated from culture medium. Lobulo-alveolar development was stimulated by 17 beta-estradiol in a dose dependent manner over a physiological range. These results support the hypothesis that estrogen plays a critical role in alveolar development in the mammary gland. In this report an in vitro model of mammary development is identified in which the effects of estrogen are morphologically described and quantified.

Expression of a renal type I sodium/phosphate transporter (NaPi-1) induces a conductance in Xenopus oocytes permeable for organic and inorganic anions

Two distinct molecular types (I and II) of renal proximal tubular brush border Na+/Pi cotransporters have been identified by expression cloning on the basis of their capacity to induce Na+-dependent Pi influx in tracer experiments. Whereas the type II transporters (e.g., NaPi-2 and NaPi-3) resemble well known characteristics of brush border Na+/Pi cotransport, little is known about the properties of the type I transporter (NaPi-1). In contrast to type II, type I transporters produced electrogenic transport only at high extracellular Pi concentrations (> or =3 mM). On the other hand, expression of NaPi-1 induced a Cl- conductance in Xenopus laevis oocytes, which was inhibited by Cl- channel blockers [5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) > niflumic acid >> 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid]. Further, the Cl- conductance was inhibited by the organic anions phenol red, benzylpenicillin (penicillin G), and probenecid. These organic anions induced outwardly directed currents in the absence of Cl-. In tracer studies, we observed uptake of benzylpenicillin with a Km of 0.22 mM; benzylpenicillin uptake was inhibited by NPPB and niflumic acid. These findings suggest that the type I Na+/Pi cotransporter functions also as a novel type of anion channel permeable not only for Cl- but also for organic anions. Such an apical anion channel could serve an important role in the transport of Cl- and the excretion of anionic xenobiotics.

Estradiol effect on rate of proliferation of rat carotid segments: effect of gender and tamoxifen

Using organ culture of carotid artery segments from sexually mature male and female rats, we examined the effect of estradiol 17 beta on proliferation. The index of cell proliferation was [3H]thymidine uptake. Estradiol 17 beta (0.18-0.36 microM) inhibited the uptake of thymidine in a concentration-dependent manner (p < 0.05). Estradiol 17 beta inhibited [3H]thymidine uptake only in the absence of the weak estrogen receptor agonist phenol red and in carotid artery segments from sexually mature female (p < 0.01) but not male rats. Tamoxifen (0.1 and 1 microM), a partial agonist of estrogen receptors, significantly inhibited thymidine uptake (p < 0.01). However, preincubation of the segments with tamoxifen (0.1 and 1.0 microM) for 4 h before the exposure to estradiol, blocked estradiol 17 beta-induced inhibition of thymidine uptake (p < 0.05 and p < 0.01 for 0.1 and 1.0 microM, respectively). The cyclooxygenase inhibitor indomethacin (5 microM) did not affect either the basal [3H]thymidine uptake or the estradiol 17 beta-induced inhibition of that uptake. This latter finding suggests that prostacyclin or prostaglandin E2 does not mediate the inhibitory response to estradiol 17 beta. The results of these experiments suggest that estradiol 17 beta-induced inhibition of proliferation of rat carotid artery segments is mediated through activation of estrogen receptors.

The improved organ maintenance of the human sebaceous gland: modeling in vitro the effects of epidermal growth factor, androgens, estrogens, 13-cis retinoic acid, and phenol red

We have previously reported that human sebaceous glands can be maintained for up to 14 d as whole organs with full retention of the physiological rate and pattern of new cell formation, but we have also reported that the newly formed cells did not differentiate normally, causing a progressive loss of lipogenesis in vitro. We now show that this abnormal sebocyte differentiation was attributable to the presence of epidermal growth factor (EGF) and phenol red in our maintenance medium. In their absence, human sebaceous glands apparently retain in vivo rates of cell division and lipogenesis over 7 d of maintenance in addition to a retention of in situ morphology. This is reversible on the re-addition of 10 ng EGF/ml and 10 mg phenol red/ml. The addition of 600 pM 17 beta-estradiol results in a significant fall in the rate of lipogenesis over 7 d of maintenance, without affecting the rate of cell division. This effect is apparently due to abnormal differentiation of newly formed sebocytes. Neither 1 nM testosterone nor 1 nM dihydrotestosterone (DHT) has any effect on rates of cell division of lipogenesis over 7 d. In the presence of phenol red, however, 1 nM testosterone or 1 nM DHT cause a significant reduction in the rate of lipogenesis over 7 d of maintenance. One micromolar 13-cis retinoic acid caused a significant reduction in the rate of lipogenesis over 7 d in both the presence and absence of phenol red. These findings show that we can model the physiological effects of steroids, EGF, and 13-cis retinoic acid in vitro.

Investigations on the specificity of thiophilic interaction for monoclonal antibodies of different subclasses

A comparative study was carried out to investigate the influence of different mouse antibody subclasses on the chromatographic behaviour on thiophilic supports. Cell-free supernatants from different mouse-mouse hybridoma cultures in a standard medium were purified on thiophilic agarose and Fractogel EMD TA. The adsorption capacities and purification factors were monitored under optimised adsorption conditions. The different isotypes did not differ significantly regarding capacity of the thiophilic matrix, but the purity of the eluted antibody fractions was significantly lower for the IgG2a subclass compared to all other murine antibodies. A significant copurification of proteins from cell culture supernatant with antibodies of the IgG2a subclass indicated a restriction in the universal nature of thiophilic interaction.

Quinine sensitive changes in cellular Na+ and K+ homeostasis of COS-7 cells caused by a lipophilic phenol red impurity

An impurity of phenol red (PRI) has been shown to markedly alter the intracellular Na+ and K+ homeostasis of several cell types. The effect of PRI seems to involve intracellular Ca(++)-dependent mechanisms. Using COS-7 cells as a model, we further characterized the mechanism of action of PRI by measuring cellular Na+/K+ contents and 86Rb+ efflux. Similar to human skin fibroblasts, in COS-7 cells calmodulin inhibition moderated the cationic transport effects of PRI. A TMB-8 dependent intracellular Ca++ pool does not seem to be involved in these transport events. We found no evidence for participation of the transcriptional-translational machinery in the effect of PRI. Both quinine and quinidine are able to prevent nearly all changes caused by PRI in the cellular Na+/K+ contents and 86Rb+ efflux. Although phenol red contained multiple impurities by high performance liquid chromatography (HPLC), phenolphthalein, a structurally close relative of phenol red, was free of any detectable contamination. Phenolphthalein elicited qualitatively similar transport changes to those observed during exposure to PRI. Regardless of the exact mechanism of action, we propose that the as yet unidentified substance is not a cellular toxin, rather it is a cationic transport modulator. Directly or indirectly, it may interact with the cellular Ca++/calmodulin system and activate some quinine/quinidine sensitive transport processes. This transport process is likely to be a Ca(++)-sensitive K+ channel but, due to the lack of specificity of quinine and quinidine, other transport mechanisms must be also considered. The chemical nature of PRI may be similar to phenolphthalein.

Comparison of three methods of antifungal susceptibility testing with the proposed NCCLS standard broth macrodilution assay: lack of effect of phenol red. National Committee for Clinical Laboratory Standards

Three microtiter plate adaptations of the NCCLS proposed standard for antifungal susceptibility testing were evaluated and compared to the NCCLS broth macrodilution method. Thirteen different fungi, including yeasts and moulds were studied. The first microtiter based method was performed exactly as described for the tube dilution assay, with the exception of performance of the assay in 100 microliter in wells of the microtiter plate. The second assay was the same as the first, except for the deletion of phenol red from the RPMI 1640. The third microtiter assay was based on the reduction of the formazan dye, XTT, after only 24 hours of incubation. All three microtiter methods compared favorably with the macrodilution method, when visually read after either 24 or 48 hours of incubation. Minimum inhibitory concentrations obtained by the XTT assay were usually lower than those obtained by the methods requiring a visual end point determination. Results were reproducible and comparable to those obtained with the NCCLS method. We conclude that microtiter plate adaptation of the NCCLS proposed standard is feasible and the presence of phenol red does not alter the results with the drugs tested. A 24 hour assay using XTT may provide a quicker and more quantitative method of susceptibility testing of fungi. Further investigation of this approach is warranted.

Phenol red is a thromboxane A2/prostaglandin H2 receptor antagonist in canine lingual arteries and human platelets

Phenol red (PR) is used as a pH indicator in cell culture medium. We found that cell culture medium containing PR relaxed canine lingual arteries (LA) contracted by the thromboxane A2/prostaglandin endoperoxide (TPE) receptor agonist (15S)-hydroxy-11-alpha-9-alpha- (epoxymethano)prosta-5Z,13E-dienoic acid (U46619). We tested the effect of PR and the TPE receptor antagonist ONO-3708 on U46619, prostaglandin F2 alpha (PGF2 alpha), phenylephrine (PE) and potassium chloride (KCl)-induced contraction of the LA and on human platelet aggregation to U46619, ADP, arachidonic acid (AA), A23187 and thrombin. U46619, PGF2 alpha, KCl and PE produced equal tension development of the LA. PR relaxed the LA contracted with U46619 and PGF2 alpha with IC50 concentrations of 18.3 +/- 10 and 37.3 +/- 8.8 microM, respectively. ONO-3708 inhibited the contractions to U46619 and PGF2 alpha with IC50 of 9.4 +/- 2.2 and 12.2 +/- 2.2 nM, respectively. However, PR (300 microM) and ONO-3708 (300 nM) did not affect contraction of the LA to KCl or PE. PR inhibited human platelet aggregation, in vitro, to AA and U46619 and second wave aggregation to ADP but did not affect thrombin or first wave ADP-mediated platelet aggregation. PR inhibited U46619 and AA-induced changes in cyclic AMP and Fura-2 calcium transients in platelets and LA. However, PR did not affect the activation of cyclic AMP or intracellular calcium ion in platelets or calcium influx and the release of intracellular calcium ion in canine LA produced by ryanodine, KCl and PE. The concentration of PR in many culture media is between 40 and 70 microM. The data support the conclusion that PR, in concentrations used as a pH indicator, is a selective antagonist of TPE receptors.