Diminished Barrier Function Research Articles

Oxidative Stress and Mitochondrial Damage Precedes Gastric Mucosal Cell Death Induced by Ethanol Administration

Although it has been speculated that active oxidants and mitochondrial membrane damages play roles in ethanol-induced gastric mucosal damages, its detail remains unknown. The present study was designed to investigate whether ethanol induces oxidative stress and mitochondrial permeability transition (MPT) before cell death of gastric mucosal cells. Rat gastric mucosal cells (RGM-1) were kept in serum-free Dulbecco's modified Eagle's medium before addition of various concentrations of ethanol. Nuclear morphological aftemations and membrane barrier dysfunction of RGM-1 cells were assessed by staining with Hoechst 33342 and propidium iodide, respectively. To assess the contribution of oxygen-derived free radicals and intracellular glutathione, scavenger of hydrogen peroxide and the hydroxyl radical, N,N-dimethylthiourea, glutathione precursor, N-acetyl-L-cysteine, and an inhibitor of alcohol dehydrogenase, 4-methylpyrazole were added before treatment with ethanol. To investigate MPT, calcein and tetramethylrhodamine methyl ester were loaded before addition of ethanol, and the changes of fluorescence intensity were monitored using a laser scanning confocal microscope. Ethanol (>5% v/v) dose-dependently increased the number of propidium iodide-positive cells, suggesting a diminished barrier function of cell membrane. After addition of ethanol, mitochondria were filled quickly with calcein indicating MPT, which was accompanied by mitochondrial depolarization, as shown by loss of tetramethylrodamine methyl ester before cell death. Ethanol-induced cell death was significantly attenuated by simultaneous incubation with either N,N-dimethylthiourea or N-acetyl-L-cysteine, suggesting the importance of intracellular redox states in inducing cellular damage, whereas such change was not attenuated by 4-methylpyrazole. Present results suggest that ethanol treatment induces intracellular oxidative stress and produces MPT and mitochondrial depolarization, which are preceding cell death in gastric mucosal cells. Intracellular antioxidants, such as glutathione, may have a significant protective action against ethanol in gastric mucosal cells.

Sensitive skin: perceptions, evaluation, and treatment

Background: Patients with sensitive skin can present a challenge for dermatologists and cosmetic chemists alike. Knowledge of this common skin condition and appropriate dermatologic treatment, in combination with a rational approach to skin-care product selection, are important to patient well-being. Objective: This report summarizes the subjective and objective findings in patients with sensitive skin while presenting a theory to explain disease physiology. Finally, a recommended treatment approach and formulation guidelines are presented. Conclusion: Sensitive skin possesses one or more of the following anatomic cutaneous changes: heightened neurosensory input, enhanced immune responsiveness, and/or diminished barrier function. Cosmetic and skin-care product formulation considerations for sensitive skin include products with a paucity of ingredients, absence of common sensitizers, minimum number of irritants, and absence of cutaneous sensory or vasodilatory stimulants.

Role in nitric oxide in Kupffer cell-mediated hepatoma cell cytotoxicity in vitro and ex vivo

The metabolic change in tumor cells (AH70, a rat hepatoma cell line) cocultured with isolated rat Kupffer cells were visualized and analyzed by a laser scanning confocal imaging system. When AH70 cells were cocultured with Kupffer cells, fluorescence intensity of rhodamine 123 (Rh123) decreased, indicating the reduction of mitochondrial function. The reduction in Rh123 was eliminated by NG-monomethyl-L-arginine (L- NMMA), an analogue of L-arginine, suggesting the involvement of nitric oxide (NO). Two hour after the cells were cocultured, membrane compromised AH70 cells which were observed as propidium from 2.8% to 25%. This increase was also attenuated by L-NMMA, suggesting that Kupffer cell-mediated injury of tumor cells largely depends on NO. The concentrations of NO-2 + NO-3 in the culture medium markedly increased after coculture of AH70 cells with Kupffer cells. Moreover, NO synthase (NOS) activity in Kupffer cells significantly increased after coculture. These in vitro results suggest that NO mediates Kupffer cell- induced tumor cell damage characterized by reduced mitochondrial function and diminished barrier function. In the ex vivo study of the perfused liver to which AH70 cells were injected via the catheter inserted into the portal vein, some AH70 cells were arrested in the upper stream of sinusoid and the fluorescence intensity of Rh123 in adherent AH70 cells decreased in a time-dependent manner within 2 hours. The number of PI-positive AH70 cells also increased 2 hours after the injection of AH70 cells. These changes were inhibited by either administration of N omega-L-nitroarginine-methylester (L-NAME) to perfusate or pretreatment of the rat liver with GdCl3, which is known to deplete Kupffer cell function. Thus, the present study suggests that NO from Kupffer cells induces mitochondrial dysfunction in tumor cells followed by membrane barrier dysfunction in the liver sinusoid. (Hepatology 1996 Jul;24(1):141-9)

Role in Nitric Oxide in Kupffer Cell-Mediated Hepatoma Cell Cytotoxicity In Vitro And Ex Vivo

The metabolic change in tumor cells (AH70, a rat hepatoma cell line) cocultured with isolated rat Kupffer cells were visualized and analyzed by a laser scanning confocal imaging system. When AH70 cells were cocultured with Kupffer cells, fluorescence intensity of rhodamine 123 (Rh123) decreased, indicating the reduction of mitochondrial function. The reduction in Rh123 was eliminated by NG–monomethyl–L–arginine (L– NMMA), an analogue of L–arginine, suggesting the involvement of nitric oxide (NO). Two hour after the cells were cocultured, membrane compromised AH70 cells which were observed as propidium from 2.8% to 25%. This increase was also attenuated by L–NMMA, suggesting that Kupffer cell–mediated injury of tumor cells largely depends on NO. The concentrations of NO–2 + NO–3 in the culture medium markedly increased after coculture of AH70 cells with Kupffer cells. Moreover, NO synthase (NOS) activity in Kupffer cells significantly increased after coculture. These in vitro results suggest that NO mediates Kupffer cell– induced tumor cell damage characterized by reduced mitochondrial function and diminished barrier function. In the ex vivo study of the perfused liver to which AH70 cells were injected via the catheter inserted into the portal vein, some AH70 cells were arrested in the upper stream of sinusoid and the fluorescence intensity of Rh123 in adherent AH70 cells decreased in a time–dependent manner within 2 hours. The number of PI–positive AH70 cells also increased 2 hours after the injection of AH70 cells. These changes were inhibited by either administration of N omega–L–nitroarginine–methylester (L–NAME) to perfusate or pretreatment of the rat liver with GdCl3, which is known to deplete Kupffer cell function. Thus, the present study suggests that NO from Kupffer cells induces mitochondrial dysfunction in tumor cells followed by membrane barrier dysfunction in the liver sinusoid.

The effect of branched-chain amino acid-enriched parenteral nutrition on gut permeability

In situations of catabolic stress, the gut becomes atrophic and has a diminished barrier function as evidenced by an increased permeability to a variety of molecules. It is known that the parenteral administration of branched-chain amino acids (BCAA) reduce gut atrophy. The aim of this study was to examine the effect of BCAA-enriched solutions of parenteral nutrients on gut permeability. A secondary aim was to observe the association between gut permeability and variables that have been used to assess jejunal atrophy. Central venous lines were inserted into 30 rats before randomization to receive nutritional support with: (1) a conventional parenteral solution (CPN), (2) A 2.0% BCAA-enriched solution (BCAA), or (3) rat food ad lib (Rat Food). The rats were assessed after 7 d for nutritional status, gut morphology, and gut permeability ratio (ratio of the permeability to 14C raffinose and 3H mannitol). We found that rats in the Rat Food Group lost the least amount of weight, had the least amount of jejunal atrophy, and had better preservation of barrier function as determined by gut permeability. When compared with the CPN Group, the BCAA Group had better preservation of jejunal morphology and protein content ( p < 0.05), but a similar gut permeability. A cross-correlation matrix demonstrated a significant negative correlation between permeability to mannitol and mucosal weight, mucosal protein content and mucosal DNA content. Branched-chain amino acid-enriched parenteral nutrition reduced gut atrophy but not the gut permeability associated with parenteral nutrition. In the parenterally nourished rat model, atrophy of the jejunum is associated with increased permeability to small molecules.

The effect of minimum luminal nutrition on bacterial translocation and atrophy of the jejunum during parenteral nutrition

In situations of catabolic stress, the gut becomes atrophic and may have diminished barrier function as evidenced by an increase in bacterial translocation. The aim of this study was to examine the effect of minimum luminal nutrition during parenteral nutrition on the extent of jejunal atrophy and rate of bacterial translocation. Central venous lines were inserted into 30 rats before they underwent randomization to receive nutritional support with: (a) conventional parenteral nutrition; (b) conventional parenteral nutrition with 3 g/day of rat food (i.e., minimum luminal nutrition); or (c) rat food ad libitum. The rats were assessed after 10 days for nutritional status, extent of jejunal atrophy, caecal flora, as well as the extent of bacterial translocation to the mesenteric lymph nodes, liver and spleen. Rats in the rat food ad libitum group lost the smallest amount of weight and had the least amount of jejunal atrophy, yet had a similar rate of bacterial translocation as the parenterally nourished groups. When compared with the conventional parenteral nutrition group, the minimum luminal nutrition group had better preservation of the weight of the small bowel and its isolated mucosa (P < 0.01), but had a similar rate of bacterial translocation. Minimum luminal nutrition reduced the extent of atrophy of the gut but did not affect the incidence of bacterial translocation. It is inferred that there is no direct relationship between the extent of mucosal atrophy and incidence of bacterial translocation.

Role of nitric oxide and thromboxane A2 in hypoxic pulmonary vasoconstriction

The metabolic change in tumor cells (AH70, a rat hepatoma cell line) cocultured with isolated rat Kupffer cells were visualized and analyzed by a laser scanning confocal imaging system. When AH70 cells were cocultured with Kupffer cells, fluorescence intensity of rhodamine 123 (Rh123) decreased, indicating the reduction of mitochondrial function. The reduction in Rh123 was eliminated by NG-monomethyl-L-arginine (L- NMMA), an analogue of L-arginine, suggesting the involvement of nitric oxide (NO). Two hour after the cells were cocultured, membrane compromised AH70 cells which were observed as propidium from 2.8% to 25%. This increase was also attenuated by L-NMMA, suggesting that Kupffer cell-mediated injury of tumor cells largely depends on NO. The concentrations of NO-2 + NO-3 in the culture medium markedly increased after coculture of AH70 cells with Kupffer cells. Moreover, NO synthase (NOS) activity in Kupffer cells significantly increased after coculture. These in vitro results suggest that NO mediates Kupffer cell- induced tumor cell damage characterized by reduced mitochondrial function and diminished barrier function. In the ex vivo study of the perfused liver to which AH70 cells were injected via the catheter inserted into the portal vein, some AH70 cells were arrested in the upper stream of sinusoid and the fluorescence intensity of Rh123 in adherent AH70 cells decreased in a time-dependent manner within 2 hours. The number of PI-positive AH70 cells also increased 2 hours after the injection of AH70 cells. These changes were inhibited by either administration of N omega-L-nitroarginine-methylester (L-NAME) to perfusate or pretreatment of the rat liver with GdCl3, which is known to deplete Kupffer cell function. Thus, the present study suggests that NO from Kupffer cells induces mitochondrial dysfunction in tumor cells followed by membrane barrier dysfunction in the liver sinusoid. (Hepatology 1996 Jul;24(1):141-9)

Pseudo-acylceramide with linoleic acid produces selective recovery of diminished cutaneous barrier function in essential fatty acid-deficient rats and has an inhibitory effect on epidermal hyperplasia.

Pseudo-acylceramides with different acyl properties were investigated for their capacity to restore diminished barrier function in essential fatty acid-deficient rats. Daily topical applications of synthetic pseudo-acylceramides containing ester-linked linoleic acid caused a dose-dependent, significant reduction of transepidermal water loss (TEWL). Both other pseudo-acylceramides with ester-linked oleic acid or saturated alkyl chains and ordinary ceramides exhibited a poor effect on recovery of TEWL. Furthermore, pseudoceramide containing ether-linked linoleic acid, which is biologically inactive in terms of degradation by hydrolytic enzymes, also induced a significant and similar increase in the barrier function. This restoration of barrier function by pseudo-acylceramides with linoleic acid was accompanied by suppressed DNA synthesis in the EFAD rat epidermis. In UVB-irradiated guinea pig skin, topical applications of the pseudo-acylceramides with linoleic acid immediately after the exposure significantly reduced epidermal hyperplasia, secondary to markedly diminished barrier disruption, whereas linoleic acid itself did not. A comparison of both the anti-hyperplasia and the barrier recovery effects in the series of pseudo-ceramide derivatives examined revealed that the suppressive effect on the induced epidermal hyperplasia was paralleled by the recovery of the barrier defect in EFAD rats. These findings directly suggest that acylceramide with an ester-linked linoleic acid has an essential role in the epidermal permeability barrier.