Drynaria quercifolia suppresses paracetamol­induced hepatotoxicity in mice by inducing Nrf-2.

Paracetamol is a popular and safe drug preferred by victims of pain or pyrexia; however, its overdose or abuse is a growing concern worldwide. Here the hepatoprotective effect of an ethnomedicinal plant Drynaria quercifolia against paracetamol­induced toxicity in murine model is demonstrated. This fern, native to tropical countries including the Northeast India, is used by local tribes to treat inflammatory conditions. Paracetamol 500 mg/kg body weight was orally administered on alternate days for a period of 21days to mimic a chronic overdose. Drynaria quercifolia acetone extract (DQA) treatment interspaced with paracetamol significantly decreased serum biomarkers of hepatotoxicity (ALT, AST and ALP) renal toxicity (urea, creatinine), lipid peroxidation level, histological damage in liver and kidney. The protein and mRNA expressions of the transcription factor, Nrf2, and its target antioxidant genes (SOD1, CAT and GST) as well as activities of these antioxidant enzymes were downregulated by paracetamol administration but significantly recovered following the DQA treatment (Tab. 3, Fig. 5, Ref. 31). Keywords: acetaminophen/paracetamol, Drynaria quercifolia, renal toxicity, hepatotoxicity, Nrf-2.

A Walk with Lu-177 PSMA: How Close we Have Reached from Bench to Bedside?

Metastatic castration-resistant prostate cancer (mCRPC) is a natural sequela in advanced prostate cancer following resistance to standard treatment regimes, where patients develop with rising PSA, bone pains, and high disease volume. Further palliative treatment is the need of the hour for ensuring disease control and quality of life. In recent times, many novel methods have been evolved for these patients. Endo-radioligand therapy with Lutetium 177 prostate-specific membrane antigen 617 (Lu-177 PSMA) based on the Theranostic concept has emerged as a promising tool among these. We present here the current status of Lu177-PSMA for mCRPC patient and future directions.

Biodegradation of sulfosulphuron in agricultural soil by Trichoderma sp.

UNLABELLED: Sulfosulphuron-degrading fungus was isolated by enrichment technique from the sulfosulphuron-contaminated soil of wheat rhizosphere. To assess the biodegradation potential of isolated Trichoderma sp., minimal potato dextrose agar broth with different levels of sulfosulphuron (up to 2 g l(-1) ) was evaluated in the growth and biotransformation experiments. ESI LC-MS/MS analysis revealed the presence of degradation products 2-amino-4,6-dimethoxypyrimidine (I) and 2-ethylsulfonyl imidazo{1,2-a} pyridine-3-sulfonamide-2-ethylsulfonyl imidazo{1,2-a} pyridine-3-sulfonamide (II) indicating the cleavage of the urea bridge and the presence of the by-product N-(4,6-dimethoxypyrimidin-2-yl)urea (III) indicating the degradation of sulfonylamide linkage. Two other metabolites, N-(4,6-dimethoxypyrimidin-2-yl)-N'-hydroxyurea (IV) and N, N'-bis(4,6-dimethoxypyrimidin-2-yl)urea (V), were also identified. From the previous reports, it was found that the degradation of sulfonyl urea herbicides took place through the chemical degradation of the sulfonylurea bridge followed by microbial degradation. During this investigation, Trichoderma sp. grew well with and degraded sulfosulphuron via both the decarboxylation on the sulphonyl urea bridge and the hydrolytic cleavage of the sulfonylamide linkage as demonstrated by the formation of metabolites. Trichoderma is nonphytopathogenic in nature, and some species of it restrict the growth of soil-dwelling phytopathogens. Therefore, it is a promising candidate for the decontamination of soil from sulfosulphuron residues. SIGNIFICANCE AND IMPACT OF THE STUDY: The degradation of sulfosulphuron by any individual fungus is being reported for the first time. Trichoderma sp. isolated from wheat-rhizospheric soil could survive in minimal broth rich in sulfosulphuron. Previous reports have described the complete degradation of any sulfonyl urea herbicides by micro-organisms only after the pH-dependent chemical hydrolysis of the sulfonyl urea bridge of the herbicide. This study demonstrates the novel result that the Trichoderma sp. utilized the sulfosulphuron as a sole carbon source and degraded it by cleaving sulfonyl urea bridge and sulfonylamide linkage. Thus, the application of Trichoderma sp., which is nonphytopathogenic, has the potential to decontaminate agricultural soil from sulfosulphuron load.

3.4 Gbit/s visible optical wireless transmission based on RGB LED.

In this paper, we experimentally realized a gigabit-class indoor visible light communication system using commercially available RGB White LED and exploiting an optimized DMT modulation. We achieved data rate of 1.5 Gbit/s with single channel and 3.4 Gbit/s by implementing WDM transmission at standard illumination levels. In both experiments, the resulting bit error ratios were below the FEC limit. To the best of our knowledge, these values are the highest ever achieved in VLC systems.

Interdistrict variations in child health status and health services utilization: lessons for health sector priority setting and planning from a cross-sectional survey in rural India.

BACKGROUND: There are limited data on interdistrict variations in child health status and health services utilization within the states of India. We conducted this study to identify and understand district-wise variations in child morbidity, mortality, healthcare seeking, and the status of health facilities in India. METHODS: A cross-sectional population-based cluster survey was conducted from April to July 2007 in 16 districts of eight states in India. Two districts with similar demographic profile and health criteria were selected from each study state. RESULTS: A total of 216 794 households and 24 812 under-5 children were surveyed. There were wide interdistrict variations in the health status of children within the same state and between different states across India. Interdistrict difference of >5 points/1000 live-births was found for infant mortality rate and under-5 mortality rate in all eight study states, while in six out of eight states this difference was >10 points/1000 live-births. Four states had a difference of >10 points/1000 live-births between respective districts for neonatal mortality rate. The interdistrict differences were also noted in childhood morbidity and health-seeking behaviour. Analysis of proportion of health facilities conforming to Indian public health standards revealed that the difference was m10% for availability of vaccines in five states, emergency services in three, laboratory services and logistics in four each, and referral facility in three of the eight study states. CONCLUSION: This study underscores an important information gap in the country where planners seem to rely heavily on a few selected national-level databases that may not be adequate at the micro level. The current process of sporadic health surveys also appears inadequate and inappropriate. There is a need for district-specific data for planning, improving quality of service and generating demand for health service utilization to improve child survival in India. The findings of this study may prove useful for child health programme planning in India.

Tunable absorber embedded with GST mediums and trilayer graphene strip microheaters.

Investigation was made of the optical response of metal-dielectric stacks-based cavity structures embedded with graphene microheaters for the purpose of perfect absorption. The absorber configuration exploits the Ge2Sb2Te5 (GST) phase changing medium, and the effects of different parametric and operational conditions on the absorption spectra were explored. The refractive indices of GST layers can be manipulated by the external electrical pulses applied to microheaters. The amplitude and duration of electrical pulses define the crystallinity ratio of the used GST mediums. The results revealed achieving perfect absorption (> 99%) in the visible and infrared (IR) regimes of the electromagnetic spectrum upon incorporating two thin GST layers of different thicknesses (in the stack) in the amorphous state. The proposed configuration showed the capability of introducing independent transition state (amorphous and/or crystalline) for each GST layer-the visible regime could be extended to the IR regime, and the perfect absorption peak in the IR regime could be broadened and red-shifted. It is expected that the structure would find potential applications in active photonic devices, infrared imaging, detectors and tunable absorbers.

Bioactive Loaded Lipid-based Nanostructures: A Novel Insight for Age-related Neurodegeneration.

Substantial affirmation suggested that oxidative stress remains an impelling target, contributing to initiate and exacerbate the multiple neurological complications in age-related neurodegeneration (ARN). Factors including gene and environmental toxins are now becoming the most threatening cause of oxidative stress, which leads to mitochondrial dysfunction of the neurons that ultimately causes permanent loss of their functionality. Clinical trials on antioxidants are still in the pipeline to access them as a potential therapeutic class. But this raised the generosity for not only to investigate the module of the antioxidant mechanism but also to justify the drug delivery and dose regimen. Biological barriers, predominantly, Blood-brain barrier (BBB) and rapid firstpass metabolism, are some of the potential obstacles for the effective targeting of the therapeutic agent. Bioactive drugs with antioxidant capacity, loaded with lipid-based Nano career system have revealed to be a novel therapeutic intervention for ARN. The review will deal with the comprehensive state-of-art methodology for the delivery of bioactive loaded lipid Nanocarriers to treat neurodegeneration. A systematic analysis of published reports will help the researchers to understand the role of natural compound loaded Nanoengineered system in the field of ARN as a potential Nano therapeutic intervention.

On the Core-Shell Nanoparticle in Fractional Dimensional Space.

The investigation of core-shell nanoparticles has been greatly exciting in biomedical applications, as this remains of prime importance in targeted drug delivery, sensing, etc. In the present work, the polarizability and scattering features of nanoparticles comprised of nano-sized dielectric/metallic core-shell structures were investigated in the fractional dimensional (FD) space, which essentially relates to the confinement of charged particles. For this purpose, three different kinds of metals-namely aluminum, gold and silver-were considered to form the shell, having a common silicon dioxide (SiO2) nanoparticle as the core. It is noteworthy that the use of noble metal-SiO2 mediums interface remains ideal to realize surface plasmon resonance. The core-shell nanoparticles were considered to have dimensions smaller than the operating wavelength. Under such conditions, the analyses of polarizability and the scattering and absorption cross-sections, and also, the extinction coefficients were taken up under Rayleigh scattering mechanism, emphasizing the effects of a varying FD parameter. Apart from these, the tuning of resonance peaks and the magnitude of surface plasmons due to FD space parameter were also analyzed. It was found that the increase of FD space parameter generally results in blue-shifts in the resonance peaks. Apart from this, the usage of gold and silver shells brings in fairly large shifts in the peak positions of wavelengths, which allows them to be more suitable for a biosensing purpose.

Elliptical metallic rings-shaped fractal metamaterial absorber in the visible regime.

Achieving the broadband response of metamaterial absorbers has been quite challenging due to the inherent bandwidth limitations. Herein, the investigation was made of a unique kind of visible light metamaterial absorber comprising elliptical rings-shaped fractal metasurface using tungsten metal. It was found that the proposed absorber exhibits average absorption of over 90% in the visible wavelength span of 400-750 nm. The features of perfect absorption could be observed because of the localized surface plasmon resonance that causes impedance matching. Moreover, in the context of optoelectronic applications, the absorber yields absorbance up to ~ 70% even with the incidence obliquity in the range of 0°-60° for transverse electric polarization. The theory of multiple reflections was employed to further verify the performance of the absorber. The obtained theoretical results were found to be in close agreement with the simulation results. In order to optimize the results, the performance was analyzed in terms of the figure of merit and operating bandwidth. Significant amount of absorption in the entire visible span, wide-angle stability, and utilization of low-cost metal make the proposed absorber suitable in varieties of photonics applications, in particular photovoltaics, thermal emitters and sensors.

Data on optimization of microprojectile bombardment parameters in development of salinity tolerant transgenic lines.

This data deals with the optimization of microprojectile bombardment particles for efficient genetic transformation in an indica rice involving AmSOD gene for development of salinity tolerant transgenic lines [1]. In this study, various parameters such as effect of genotypes, helium pressure, osmoticum, explants, flight distance, particle size, particle volume, vacuum, carrier DNA and stopping screen properties have been evaluated to determine their role in transformation of indica rice involving AmSOD gene for development of salinity tolerant Pusa Basmati 1 rice variety. To perform the transformation process, plasmid vector pCAMBIA 1305.2 was used, which harbours GUS Plus™ gene, intron from the castor bean catalase gene, pBR322 ori, kanamycin resistant gene and Xho I site. The transformants have been confirmed using slot blot, polymerase chain reaction and Southern hybridization techniques.

Antimicrobial, anti-inflammatory and wound healing activity of polyherbal formulation.

According to Ayurveda, individual herbs are insufficient to achieve a desired therapeutic effect. When it is optimized as multiple herbs composition in a particular ratio it will give a therapeutic effect in a better way with reduced toxicity. In order to develop such an intervention, the present study was intended to develop a polyherbal drug from methanolic extracts of Plumbago zeylanica Linn, Datura stramonium Linn and Argemone mexicana Linn. The study also aimed to evaluate the impact of polyherbalism on antimicrobial and antioxidant effect, thereafter the ratio of individual plant extracts was optimized accordingly to treat the wound. The poyherbal drug was put on preclinical trial to access the anti-inflammatory and wound healing activity as 2% and 5% polyherbal carbopol-940 gels. The antimicrobial activity was assessed by agar well diffusion and broth dilution method while wound healing activity was evaluated by excision and incision wound models. Topical anti-inflammatory activity was assessed by carrageenan induced paw oedema. The findings of the study revealed the synergistic antimicrobial potential of Polyherbal drug against gram-positive and negative strains. Polyherbal carbopol- 940 gels (2% and 5%w/w) promoted the wound healing and anti-inflammatory effect. The high rate of wound contraction (<0.0001), early epithelialization period (<0.0001) and increased wound breaking strength (<0.0001) were observed in 2% and 5% polyherbal gel treated group when compared to the normal control and negative control group. The antimicrobial and anti-inflammatory effect of Polyherbal drug provoked and promoted the wound healing process through accelerated remodelling of damaged tissue.

Formulation and evaluation of ethyl cellulose microspheres prepared by the multiple emulsion technique.

The aim of this study was to formulate and evaluate microencapsulated controlled release preparations of metformin hydrochloride using ethyl cellulose as the retardant material with high entrapment efficiency and extended release. Microspheres were prepared by the double emulsion solvent diffusion method. A mixed solvent system consisting of acetonitrile and dichloromethane in 1:1 ratio and light liquid paraffin were chosen as the primary and secondary oil phases, respectively. Span 80 was used as the surfactant for stabilizing the secondary oil phase. The prepared microspheres were characterized by drug loading, optical microscopy and scanning electron microscopy (SEM). The in vitro release studies were performed in a series of buffer solutions with variable pH. The drug loaded microspheres showed 55-85% of entrapment and the release was extended for up to 12 h. SEM studies revealed that the microspheres were spherical and porous in nature. Data obtained from in vitro release studies were fitted to various kinetic models and high correlation was obtained with the Higuchi model. The drug release was found to be diffusion controlled. Oral administration of the microspheres to the albino mice provided decreased plasma glucose for more than 10 h.

Scintimammography screening for recurrent breast cancer in women.

Scintimammography (SM) is a nuclear medicine technique in which a tumour seeking radionuclide is used to localize or trace an active or residual tumour in breast tissue. It involves the injection ofa radiopharmaceutical into circulation and obtaining a scan of the breast tissue l0-15 min later. This procedure has been shown to be an accurate diagnostic tool in patients with symptomatic breast lesion with a non-diagnostic mammogram and for whom characterizing the lesion becomes important. This retrospective study was done using the case records of all 72 patients who had presented for scintimammography on follow -up for breast conservation surgery from January to August 2005. The result of scintimammography done using 99mTc tetrofosmin method was compared with mammograms and cytology reports when available. A total number of 52 patients, mean age 49.4 +/- 8.71 years (range 35-67) were analyzed. The commonest presentation was induration at site of surgery. In 43 patients without recurrent disease, scintimammography correctly characterized 42 while 8 out of the 10 patients with recurrent disease confirmed by histology reports were correctly identified The sensitivity of this study was 88.8%, while specificity was 95.4%. The positive predictive value was 80%, while the negative predictive value was 95.3%. Given the non-invasiveness of scintimammography and the high diagnostic index, it is a very useful tool in breast cancer diagnosis and followup. Furthermore, the radiation dose to the patient is lower than a chest radiograph and as such the fear of radiation comparatively is milder.

Can dose reduction to one parotid gland prevent xerostomia?--A feasibility study for locally advanced head and neck cancer patients treated with intensity-modulated radiotherapy.

AIMS: Dryness of the mouth is one of the most distressing chronic toxicities of radiation therapy in head and neck cancers. In this study, parotid function was assessed in patients with locally advanced head and neck cancers undergoing intensity-modulated radiotherapy (IMRT) with or without chemotherapy. Parotid function was assessed with the help of a questionnaire and parotid scintigraphy, especially with regards to unilateral sparing of the parotid gland. MATERIALS AND METHODS: In total, 19 patients were treated with compensator-based IMRT between February 2003 and March 2004. The dose to the clinical target volume ranged between 66 and 70 Gy in 30-35 fractions to 95% of the isodose volume. Ipsilateral high-risk neck nodes received an average dose of 60 Gy and the contralateral low-risk neck received a dose of 54-56 Gy. Eight of 19 patients also received concomitant chemotherapy. RESULTS: Subjective toxicity to the parotid glands was assessed with the help of a questionnaire at 0, 3 and 6 months and objective toxicity was assessed with parotid scintigraphy at 0 and 3 months. The mean dose to the ipsilateral parotid gland ranged from 19.5 to 52.8 Gy (mean 33.14 Gy) and the mean dose to the contralateral gland was 11.1-46.6 Gy (mean 26.85 Gy). At a median follow-up of 13 months, 9/19 patients had no symptoms of dryness of the mouth (grade I), 8/19 had mild dryness of the mouth (grade II) and only 2/19 had grade III xerostomia, although the parotid gland could only be spared on one side in most of the patients. CONCLUSIONS: Minimising the radiation dose to one of the parotid glands with the help of IMRT in patients with advanced head and neck cancers can prevent xerostomia in most patients and parotid scintigraphy is a useful method of documenting xerostomia.

Controlled porosity osmotic pump for the delivery of flurbiprofen.

Controlled porosity osmotic pump contains water-soluble additives in the coating membrane, which in contact with aqueous environment dissolves and results in formation of micro porous membrane. The resulting membrane is substantially permeable to both water and dissolved drug. The drug release from this type of system is independent of pH and follows zero order kinetics. In the present investigation, effort has been made to study release mechanism of drug having low water solubility by means of controlled porosity osmotic pump. The capsule membrane was prepared by phase inversion technique. The phase inversion was carried by dipping the stainless steel mould in a 15% solution of cellulose acetate containing varying amounts of pore-forming agent, glycerol (50% to 70% w/w), followed by quenching in an aqueous solution (10% w/v glycerol), which resulted in the formation of the asymmetric membrane. The delivery orifices so formed were confirmed by release of an encapsulated dye from the capsule and scanning electron microscope (SEM). The drug selected for this study, Flurbiprofen, has low water solubility and hence is unable to create osmotic pressure to cause drug release. To enhance the solubility and its osmotic pressure, this study was conducted with a solubility enhancer sodium lauryl sulfate (SLS). The quantity of SLS was predetermined by conducting a solubility study of flurbiprofen with SLS. Release rate studies revealed that less than 10% of drug was released from the system without SLS, while about 75% release was observed from systems containing SLS. The release rate increased as the concentration of pore forming agent increased.

Is interferon-alpha and retinoic acid combination along with radiation superior to chemo-radiation in the treatment of advanced carcinoma of cervix?

Locally advanced cervical cancers comprise a large majority of the gynecologic cancers in India and other developing countries. Concurrent chemo-radiation has improved the survival of high risk stage I and stage II cervical cancers. There is no evidence that the same survival benefit has been achieved with chemo-radiation in stage III and stage IV disease. Interferon-alpha and Retinoic acid have synergistic anti-proliferative activity. In combination with radiation, they substantially enhance the sensitivity of the squamous carcinoma cells to radiation. Based on these observations from the in vitro studies, a few clinical trials have evaluated the combination of interferon-alpha and Retinoic acid, concomitant with radiation, to treat cervical cancers. The results from these early trials were encouraging and the combination had minimal toxicities. However, till date, no phase III randomized controlled trial has been done to evaluate this therapeutic modality.

Protection of translation initiation factor eIF2 phosphorylation correlates with eIF2-associated glycoprotein p67 levels and requires the lysine-rich domain I of p67.

The rate of protein synthesis in mammals is largely regulated by phosphorylation of the alpha-subunit of eukaryotic initiation factor 2 (eIF2) that is modulated by the cellular glycoprotein, p67, due to its protection of eIF2alpha phosphorylation (POEP) activity. At the N-terminus of p67, there are three unique domains, and at the C-terminus there is a conserved amino acid sequence. To analyze the importance of these domains, C-terminal deletion mutants of rat p67 were expressed constitutively in KRC-7 cells. In these cells, the phosphorylation level of the alpha-subunit of eIF2 was determined, and it was found that expression of the 1-97 amino acid segment of rat p67 increases POEP activity in vivo, and induces the endogenous levels of p67. These cells also show increased growth rate, and efficient translation of chloramphenicol acetyltransferase and beta-galactosidase reporter genes. At the N-terminus of p67, there are two unique domains: a lysine-rich domain I with the sequence (36)KKKRRKKKK(44), and an acidic residue-rich domain with the sequence (77)EEKEKDDDDEDGDGD(91). Substitution of lysine-rich domain I with (36)NMKSGNKTQ(44) in rat recombinant p67 resulted in the inhibition of its POEP activity, and substitution of the acidic residue-rich domain with (77)QNIQKALEPEAGDGA(91), resulted in no inhibition of POEP activity in KRC-7 cells. Taken together, our data suggest that protection of translation initiation factor eIF2 phosphorylation correlates with eIF2-associated glycoprotein p67 levels and requires the lysine-rich domain I of p67.

Production of platelet-derived growth factor by interleukin-1 beta and transforming growth factor-beta-stimulated retinal pigment epithelial cells leads to contraction of collagen gels.

PURPOSE: In an in vitro model of the later contractile stages of proliferative vitreoretinopathy, interleukin-1 beta (IL-1 beta) and transforming growth factor-beta (TGF-beta) stimulate the contraction of collagen gels by retinal pigment epithelial (RPE) cells. This contraction occurs after a lag period and appears not to be a direct effect of the cytokines but is mediated by another factor produced in the presence of the two cytokines. The nature of this factor has been investigated. METHODS: Human RPE cells were seeded onto collagen gels in the presence of IL-1 beta and TGF-beta. After 24 hours, the conditioned medium was removed and added to new collagen gels seeded with RPE cells, and the diameter of the collagen gels was measured after various intervals. The ability of the conditioned medium to effect contraction was determined after various treatments, including size fractionation, heating, trypsin digestion, and binding to heparin-Sepharose. The involvement of platelet-derived growth factor (PDGF) as a stimulator of contraction was tested with neutralizing antibodies and by polymerase chain reaction analyses of specific mRNAs. RESULTS: IL-1 beta and TGF-beta cause RPE cells to contract after a delay of up to 24 hours, whereas conditioned medium from cytokine-treated cells results in immediate contraction in a manner similar to that of serum. The factor in the conditioned medium causing immediate contraction was found to be heat-stable, trypsin-sensitive, and resistant to extremes of pH. It has a size of between 30 and 50 kDa and binds heparin. The factor in conditioned medium from cytokine-treated cells does not act in the presence of C-kinase inhibitors or cycloheximide, suggesting that signaling is mediated by way of protein kinase C and new protein synthesis. Stimulation of contraction by conditioned medium is inhibited by anti-PDGF antibodies, and contraction is stimulated by human PDGF. CONCLUSIONS: Contraction in the presence of cytokines is mediated by the production of PDGF or a PDGF-like molecule. This factor could have implications in the pathogenesis of proliferative vitreoretinopathy.

Cytokines and serum cause alpha 2 beta 1 integrin-mediated contraction of collagen gels by cultured retinal pigment epithelial cells.

PURPOSE: Integrins, heterodimeric cell surface glycoproteins, are involved in cell-substratum and cell-cell interactions. The role of these molecules in cytokine-mediated contraction of extracellular matrix by retinal pigment epithelial cells has been investigated in a model system that may mimic epiretinal membrane contraction during retinal detachment in proliferative vitreoretinopathy. METHODS: Retinal pigment epithelial cells were cultured on three-dimensional collagen gels that they cause to contract. The involvement of new protein synthesis and C-kinase-mediated signal transduction were studied using specific inhibitors. Cell surface integrins synthesized by pigment epithelial cells were identified using immunofluorescence, and the same antibodies were used in gel contraction assays to identify the integrin species responsible for force transduction. RESULTS: Contraction of collagen type I gels was small without cytokines but was greatly enhanced in the presence of serum or IL1 plus TGF beta. It was dependent on new protein synthesis. Contraction induced by the combination of cytokines was dependent on active protein kinases, whereas that induced by serum was not because only the former was inhibited by staurosporine, a C-kinase inhibitor. Pigment epithelial cells were found to produce beta 1, alpha 2, and alpha 5 integrins, but only alpha 2 and beta 1 appeared to participate in the contraction process because only antibodies against these integrins inhibited contraction. CONCLUSIONS: Retinal pigment epithelial cells contract an extracellular matrix in vitro in a manner similar to epiretinal membrane contraction in vivo. This contraction is mediated via cell surface glycoproteins of the integrin family that bind directly to extracellular matrix molecules.

Cytokines cause cultured retinal pigment epithelial cells to secrete metalloproteinases and to contract collagen gels.

PURPOSE: Because retinal pigment epithelial cells in epiretinal membranes remodel and contract their surrounding extracellular matrix, investigations were performed to determine if these cells can produce matrix metalloproteinases and contract collagen gels in vitro in the presence of serum or cytokines. METHODS: Cells were grown on collagen gels and their production of metalloproteinases was measured using zymography. RESULTS: Cells grown in a three-dimensional collagen gel culture system produce several latent metalloproteinases that are secreted into the gel and the surrounding medium. These include molecules of 49, 56, 66, and 100 kD. In addition, an enzyme that is probably the active form of the 66 kD enzyme is present. When interleukin 1 beta is added to the cultures, latent 49 kD and 100 kD gelatinase production is greatly stimulated and an active form of both enzymes is also observed in the medium. In contrast, transforming growth factor beta has no stimulatory effect. The cells contract the collagen gel but this is small without cytokines; however, contraction is greatly enhanced in the presence of serum or interleukin 1 beta plus transforming growth factor beta. Contraction is unlikely to be the result of metalloproteinase action on the underlying extracellular matrix because complete inhibition of these enzymes has little effect. CONCLUSIONS: These results show that cytokines can cause cultured retinal pigment epithelial cells to produce metalloproteinases that can, when activated, degrade most collagens and other structural molecules in extracellular matrix. In addition, they can stimulate the contraction of extracellular matrix constituents but there is not a simple causal relationship between matrix remodeling and contraction.