Geochemical evaluation, ecological and human health risk assessment of potentially toxic elements in urban soil, Southern India

Roadside soil contamination is mostly caused by human-caused pollutant deposition. PTEs are among the many substances that are harmful for both humans and the environment. PTE concentrations in roadside soil in Chennai, southern India, have been determined in this study. To evaluate the seriousness of the threats, more environmental and geochemical indices have been applied. 83 soil samples have been obtained from the study regions and focusing on important roads. Elemental analysis has been analyzed with ED-XRF and sieve-filtered samples focused on PTEs such as arsenic, barium, cobalt, chromium, copper, iron, potassium, nickel, lead, thorium, titanium, zinc, and uranium. Significant metallic variations have been found in soil samples around roads by the investigation. The elements this study examined section ascending in the following sequence: Fe > Ti > Zn > Cr > Pb > Cu > Ni > Th > As > U > K. In the research area, the CD classification denotes high contamination, whereas the CF indices show mild to significant pollution. PLI indicates moderate to high pollution, whereas EF suggests excessive enrichment. Igeo demonstrates a range from uncontaminated to highly contaminated. PERI showed high levels in the northern study region, whereas GUFI shows several hot spots indicating moderate to severe pollution. The Hazard Index (HI) values for all metals were less than one, demonstrating the absence of non-carcinogenic risks for both adults and children. Multivariate data show natural and anthropogenic PTEs in roadside soil. In addition, a soil quality monitoring system is needed to mitigate continual contamination risks.

Wound healing activities of PVA-urea composites from Ormocarpum cochinchinense

The aim of this work is to prepare ternary blended polyvinyl alcohol (PVA)-urea hydrogels containing Ormocarpum cochinchinense, Cinnamomum zeylanicum and antibiotic cephalexin by freezing-thawing method in order to assess the wound healing qualities. In addition to being a synthetic polymer, PVA is a recyclable and biocompatible artificial polymer blend that has attracted a lot of interest in biological applications. The freezing-thawing process with PVA-urea blend is used to make hydrogel film. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and swelling investigations were carried out for the composite membranes. Biological studies involving antibacterial, antifungal, cytotoxicity and wound healing activities were also carried out for the composite membranes. The composite membrane developed has a lot of potential for wound dressing and other applications.

Aging Skin and Natural Bioactives that Impede Cutaneous Aging: A Narrative Review

The skin aging which entails modifications in the entire skin and skin support system is caused as a result of complex blend of intrinsic and extrinsic factors. The main objective of this review is to provide critical insights into the effect of the aging determinants (intrinsic and extrinsic) on aging skin and to focus on a few classes of natural bioactives that were reported to counteract symptoms of cutaneous aging, pose potential, and beneficial health effect on aging skin supported with relevant scientific evidence. The narrative review of this cutaneous antiaging study incorporating the literature findings was retrieved from the search of computerized databases PubMed and Scopus, hand searches, and authoritative books. The antiaging skin care approach of using bioactives are basically nutritional hormetins, available from our natural heritage, identified as potent free radical scavengers, antioxidants, moisturizers, cell repairing agents, and ultraviolet protectives which have started to seek considerable attention among researchers and consumers due to the undesirable effect of chemical-based constituents on human health and environment. With the booming antiaging strategies, beauty has become the prime factor in considering one's health and overall "wellness". As promoting healthy aging is essential, the objective of aesthetic dermatology should shift from cosmetic interventions to the betterment of quality of life of aging society. The paper also discusses on certain artificial learning/machine-based algorithms, useful in screening of bioactive ingredients, helpful in developing of more tailored formulations. This narrative overview on skin antiaging natural bioactives and artificial learning-based bioactive screening approaches contributes for the improvement in dermatological drug discovery, in the development of novel targeted lead compounds and accelerates aging research and pharmaceutical research.

PI3K/AKT Signaling Tips the Balance of Cytoskeletal Forces for Cancer Progression

The PI3K/AKT signaling pathway plays essential roles in multiple cellular processes, which include cell growth, survival, metabolism, and motility. In response to internal and external stimuli, the PI3K/AKT signaling pathway co-opts other signaling pathways, cellular components, and cytoskeletal proteins to reshape individual cells. The cytoskeletal network comprises three main components, which are namely the microfilaments, microtubules, and intermediate filaments. Collectively, they are essential for many fundamental structures and cellular processes. In cancer, aberrant activation of the PI3K/AKT signaling cascade and alteration of cytoskeletal structures have been observed to be highly prevalent, and eventually contribute to many cancer hallmarks. Due to their critical roles in tumor progression, pharmacological agents targeting PI3K/AKT, along with cytoskeletal components, have been developed for better intervention strategies against cancer. In our review, we first discuss existing evidence in-depth and then build on recent advances to propose new directions for therapeutic intervention.

Effect of a tropical cyclone on the distribution of heavy metals in the marine sediments off Kameswaram, Southeast coast of India

Cyclones and heavy rainfalls are the main reasons for incessant environmental aggravation in the coastal regions and the distribution of pollutants from the contaminated terrestrial areas to the offshore regions. Twenty-five surface sediment samples were collected off Kameswaram, SE coast of India, and assessed for their geochemical and sedimentological characteristics post Cyclone Gaja. Sediment texture and various geochemical analyses were carried out to assess the metal distribution in the study area. Environmental impacts caused by heavy metal contamination in the marine sediments were assessed using different sediment pollution indices and it was found that metals such as Cu, Zn, Ni, and Co were moderately contaminated. Fe and Cr were uncontaminated to moderately contaminated, and Mn fall under the uncontaminated category. Multivariate statistical analyses revealed that the enrichment of organic-rich mud helps in entrapping the heavy metals, thus polluting the environment. Moreover, these metals were mainly derived from anthropogenic activities.

Cytoskeletal Dynamics in Epithelial-Mesenchymal Transition: Insights into Therapeutic Targets for Cancer Metastasis

In cancer cells, a vital cellular process during metastasis is the transformation of epithelial cells towards motile mesenchymal cells called the epithelial to mesenchymal transition (EMT). The cytoskeleton is an active network of three intracellular filaments: actin cytoskeleton, microtubules, and intermediate filaments. These filaments play a central role in the structural design and cell behavior and are necessary for EMT. During EMT, epithelial cells undergo a cellular transformation as manifested by cell elongation, migration, and invasion, coordinated by actin cytoskeleton reorganization. The actin cytoskeleton is an extremely dynamic structure, controlled by a balance of assembly and disassembly of actin filaments. Actin-binding proteins regulate the process of actin polymerization and depolymerization. Microtubule reorganization also plays an important role in cell migration and polarization. Intermediate filaments are rearranged, switching to a vimentin-rich network, and this protein is used as a marker for a mesenchymal cell. Hence, targeting EMT by regulating the activities of their key components may be a potential solution to metastasis. This review summarizes the research done on the physiological functions of the cytoskeleton, its role in the EMT process, and its effect on multidrug-resistant (MDR) cancer cells-highlight some future perspectives in cancer therapy by targeting cytoskeleton.

Bioaccumulation of heavy metals in water, sediment, and tissues of major fisheries from Adyar estuary, southeast coast of India: An ecotoxicological impact of a metropolitan city

Heavy metal content in water, sediment, and tissues of six commonly used edible fishes from Adyar estuary, southeast coast of India, was assessed for metal bioaccumulation. The enrichment of metals in estuarine sediment is due to the discharge of contaminated water from the Chennai Metropolis. The enrichment factor indicated that metals such as Cr (EF=30.9) and Cu (EF=31.9) are highly enriched and fall under the very severe category. Bioaccumulation factor (BAF) revealed that the concentration of heavy metals viz. Ni, Cr, Pb, Cu, Co, Zn, Fe, and Mn in different tissues of fishes was several times higher than their concentrations in water. Moreover, high concentration of heavy metals, especially Cu and Cr was noticed in the muscle and liver tissues of the fishes which are higher than the WHO standards. Among the studied fishes, Arius parkii and Gerres oyena showed higher levels of bioaccumulation in terms of toxic metals.

Na2VO(HPO4)2: an original phase solved by continuous 3D electron diffraction and powder X-ray diffraction

The new phase Na2VO(HPO4)2 was synthesized by sodium/proton ion exchange between NaI and VO(H2PO4)2 in hexanol. The exchange of two protons by two sodium ions causes a structural reorganization leading to a new original phase. The crystal structure was solved by continuous 3D Electron Diffraction, consisting of recording a video in diffraction mode during the continuous sample holder rotation in order to acquire a complete dataset in a shortest time in order to avoid the deterioration of this electron beam sensitive material. The individual Electron Diffraction patterns were extracted from the video, processed by conventional electron diffraction crystallography programs (PETS, JANA2006) and the resulting structural model calculated by the charge flipping algorithm was refined from powder X-ray diffraction data. This material crystallizes in an orthorhombic unit cell in the Iba2 (45) space group, with the cell parameters a = 13.86852(19), b = 13.7985(2), c = 7.47677(9). Electrochemical studies show that up to 0.66 Na f.u.-1 could be removed from Na2VO(HPO4)2.

Trace metal contamination in the marine sediments off Point Calimere, Southeast coast of India

Twenty-five offshore sediment samples were collected after the Gaja cyclone to evaluate the sediment quality in terms of its metal concentration. The samples were examined for organic matter, textural characteristics, calcium carbonate, and trace metals (Fe, Mn, Ni, Co, Cu, and Cr). The geo-accumulation index, enrichment factor, contamination factor, and pollution load index revealed that the study area was highly contaminated with Cu, Zn, and Co. Reasonable to extensive contamination was observed for Fe, Cr, and Ni, whereas Mn was under the uncontaminated category. Statistical analyses revealed that the contamination of Cu, Zn, and Ni are mainly originated from human activities such as boat navigation, fuel combustion, and tourism. Cyclones such as Gaja cause ecological disturbances of the terrestrial and transitional environments and also increase the level of offshore contamination by flooding the contaminated coastal landforms and transporting the contaminants to the sea.

Attenuation of oxidative stress in arthritic rats by ethanolic extract of Albizia procera benth bark through modulation of the expression of inflammatory cytokines

ETHNOPHARMACOLOGICAL RELEVANCE

Albizia procera L. (Leguminosae) commonly known as Konda vagai in Tamil, is used for the treatment of stomach and intestinal disorders. A decoction of the bark is prescribed for rheumatism and haemorrhage. Traditionally, literature claims Albizia procera as a drug to have antirheumatic properties and hence used by Tribal for the management of chronic rheumatism. Consequently, the present study has been undertaken to illustrate the beneficial outcome of Albizia procera in adjuvant induced arthritic rat model with respect to its antioxidant and anti-inflammatory activities.

AIM OF THE STUDY

The present study is aimed to investigate the oxidative stress and the expression of inflammatory markers in arthritic rats treated with ethanolic bark extract of Albizia procera.

MATERIALS AND METHODS

Ethanolic bark extract was characterized by HPTLC analysis. Acute oral toxicity study was performed according to the OECD test guideline 423 - Acute toxic class method. The anti-inflammatory effect of ETBE (100, 200 mg/kg/day/p.o.) was evaluated in complete Freund's adjuvant induced arthritic rats using diclofenac as positive control (0.3 mg/kg/day/p. o.). Plasma levels of interleukins TNF- α, IFN-α, IL-2, IL-6, myeloperoxidase and Cathepsin D levels were measured to assess the inflammatory effect of ETBE extract of Albizia procera. Further, the effect of ETBE on superoxide dismutase (SOD), glutathione peroxidase (GPX), reduced glutathione (GSH) and lipid peroxidation (LPO) were assessed in plasma.

RESULTS

HPTLC analysis showed the presence of 0.57% w/w of biochanin-A in ETBE. ETBE did not show any toxic signs up to 2000 mg/kg body weight. It exhibited the significant anti-inflammatory and antioxidant potential and did not show mortality up to 2000 mg/kg body weight. ETBE treatment significantly reduced the levels of TNF- α, IFN-α, IL-2, IL-6 and myeloperoxidase, and increased cathepsin D levels compared to vehicle treated animals. SOD, GSH and GPX levels were significantly restored to normal levels while LPO was significantly reduced at 200 mg/kg b. wt. Treated animals. Histopathological studies showed complete cartilage regeneration and near normal joint in ETBE treated arthritic rats.

CONCLUSION

ETBE demonstrated potent anti-inflammatory activity by modulating the expression of inflammatory cytokines and restoring the antioxidant enzyme levels.

Trace element contamination in marine sediments along the southeast Indian shelf following Cyclone Gaja

In this study, twenty seven surface sediments were collected off Pushpavanam, Nagapattinam coast, southeast coast of India for understanding the sedimentological and geochemical behaviour after the Cyclone Gaja. The sediment samples were analysed for texture, organic matter (OM), carbonates, and trace metals such as Cr, Cu, Zn, Ni, Co including Fe and Mn. The Geoaccumulation index, contamination factor, enrichment factor and pollution load index revealed that Cu, Zn, Ni and Co is highly contaminated in the study area. Fe and Cr are moderately to considerably contaminated, while Mn shows uncontaminated. The principal component analysis also confirms the concentration of Cu, Zn, Ni and Co were mainly derived from the anthropogenic sources and related activities. Since Cyclones like Gaja often causes frequent ecological disturbance to the coastal environments and it distributes pollutants such as trace elements from localized area of contamination to offshore.

Water quality of the Uppanar estuary, Southern India: Implications on the level of dissolved nutrients and trace elements

The current status of the water quality in terms of nutrients and trace elements were assessed in the Uppanar river estuary, Southern India. Twenty-five sampling stations were monitored in the study area, which is dominated by anthropogenic activities such as agriculture, settlements and fishing harbour in the downstream. Whereas, the upstream and midstream is dominated by barren lands and industrial hub respectively. Nutrients and trace elements such as nitrate, phosphate, iron and lead exceed the permissible limit of WHO drinking water guidelines. The water quality index derived from WHO permissible limits reveal that most of the samples fall under fair to good category. The marginal to fair water quality is noticed in the midstream to downstream region, where anthropogenic activities are high. The multivariate statistical analysis divulges that the overall water quality is controlled by two major sources such as natural weathering of soil/bedrock and agricultural and industrial activities.

Seasonal variations and environmental risk assessment of trace elements in the sediments of Uppanar River estuary, southern India

Twenty four surface sediments were gathered from the Uppanar river estuary, southern India to evaluate the trace element contamination risk in the sediments. The circulation of organic matter and calcium carbonate were controlled by algal blooms and shell fragments. Moreover, the concentrations of iron and manganese in the estuarine sediments were possibly contributed by riverine sources and geogenic processes. The geoaccumulation index, enrichment factor and contamination factor reveals that the sediments were contaminated by copper and chromium. The pollution load index recommends that the estuarine sediments have the risk of pollution. The sediment pollution index highlights that the majority of the sediments are low polluted sediments. The potential ecological risk index discloses that the Uppanar river estuary is under moderate risk. The statistical analysis reveals that the organic matter content is managed by fine fractions and the majority of the trace elements are associated with each other having similar origin.

Trace element concentrations in reef associated sediments of Koswari Island, Gulf of Mannar biosphere reserve, southeast coast of India

Extensive field work was conducted in order to assess the sediment pollution level and potential ecological risk on coral reef ecosystem. Thirty three surface sample was collected using grid sampling technique. The calcium carbonate and organic matter were primarily controlled by the distribution of coral rubbles and seagrass meadows. The concentration of trace elements is higher than the crustal average in few locations and the same result was derived from index calculations. However, the significant concentration of lead was observed throughout the study area. The elevated level of lead is probably due to coal incinerating power plants, and confluence of urban runoff from the nearby coastal areas. Based on the sediment pollution index, the majority of the sediments belongs to highly polluted to dangerously polluted category. The ecological risk indicates that the sediments are under low risk to moderate risk category and this result was proved by correlation analysis.

Spatial risk assessment and trace element concentration in reef associated sediments of Van Island, southern part of the Gulf of Mannar, India

Forty eight surface sediment samples were collected from the vicinity of Van Island in order to assess the sediment pollution level and potential ecological risk on coral reef ecosystem. The analytical and correlation results indicate a distribution of elements is chiefly controlled by the CaCO₃ and OM. The enrichment factor and geoaccumulation index show the elevated level of Pb in the surface sediments is due to application of lead petrol and coal incinerating power plants. The sediment pollution index reveals that majority of the sediments falling under highly polluted sediment category (35.4%) followed by moderately polluted (25%) and dangerous sediment category (14.58%). The potential ecological risk suggests that nearly 66.6% of the samples falling under the low risk category, moderate risk category (20.8%) followed by considerable risk category (8.33%) and very high risk category (4.1%). The accumulation level of trace elements clearly suggests that the coral reef ecosystem is under low risk.

Assessment of trace element accumulation in surface sediments off Chennai coast after a major flood event

The present study was conducted to assess the trace element concentration in marine surface sediments after major flood event of Chennai metropolis, India. Thirty surface samples were collected from off Chennai coast. Trace elements, organic matter, CaCO₃, sand-silt-clay and C/N ratios were studied to understand the accumulation dynamics on sediments. The elemental concentration, calcium carbonate and OM distribution suggest that they are derived from urban runoff and transported through Adyar and Cooum Rivers. The enrichment factor reveals that the sediments are enriched by Pb, Cu, Zn, Cr, Co, Ni followed by Fe. The observed Igeo value shows that the samples are contaminated by Pb, Cu and Zn. The elemental concentration of the surface sediments is low when compared to other coastal region except Pb. The elevated level of Pb in the surface sediments is probably due to migration of contaminated urban soil from industrial and transportation sectors into marine environment.

Evaluation and quantification of angiogenesis activity of terminalia bellirica roxb, by mice sponge implantation method

Angiogenesis represents an excellent therapeutic target for the treatment of cardiovascular diseases. It is a potent physiological process that underlies the natural manner in which our bodies respond to a diminution of blood supply to vital organs, namely the production of new collateral vessels to overcome the ischemic state. This present study is aimed to evaluate and quantify the Angiogenic potential of Terminalia bellirica Roxb, by in vivo mice sponge implantation assay. Here, gelatin sponge with or without Ethanolic extract of Terminalia bellirica leaf (EETB - 0.3 mg and 0.5 mg, respectively) were subcutaneously injected into Swiss albino mice, and 14 days later, the implanted sponges was excised and histologically examined. The stained section showed that sponge containing EETB had produced more vessels in gels than sponges alone. The new vessels were abundantly filled with intact Red blood corpuscles (RBCs), which indicate the formation of a functional vasculature inside the sponges and blood circulation in newly formed vessels by angiogenesis which is induced by EETB. It also measured that the hemoglobin content inside the sponges: Whereas, hemoglobin in control was nearly 0.3 μg, EETB cases the hemoglobin quantity was markedly enhanced to about 17 μg. Taken together, it demonstrated that Ethanolic extract of Terminalia bellirica leaf exhibited a profound angiogenic activity in vivo. The phytochemical screening and qualitative instrumental analysis of EETB reveals the presence of proteins and Phytosterols. The promising angiogenic potential may be due to the presence of the above chemical constituents. Further study is required to define more precisely the molecular mechanisms by which Ethanolic extract of Terminalia bellirica leaf modulates endothelial cell function and gene expression, as well as the pathological relevance of these findings.

Equilibrium, kinetic and thermodynamic studies of adsorption of fluoride onto plaster of Paris

Batch sorption system using plaster of Paris as an adsorbent was investigated to remove fluoride ions from aqueous solutions. The system variables studied include initial concentration of the sorbate, agitation time, adsorbent dose, pH, co-ions and temperature. The experimental data fitted well to the Freundlich and Langmuir isotherms. Thermodynamic parameters such as DeltaH degrees , DeltaS degrees and DeltaG degrees were calculated indicating that the adsorption was a spontaneous and exothermic. Kinetic studies reveal that the adsorption is first order. A mechanism involving three stages (external surface adsorption, intraparticle diffusion and final equilibrium) has been proposed for the adsorption of F(-) onto plaster of Paris. XRD patterns of the adsorbent were recorded to get a better in sight into the mechanism of adsorption process.

High resolution sonography for analysis of meniscal injuries

High resolution ultrasonography was done prospectively in 51 adult patients with clinically suspected meniscal injuries to evaluate the sensitivity and specificity of ultrasonography as a primary diagnostic tool and to see if it was possible to evaluate the site, extent and size of the tear. All cases were confirmed arthroscopically; ultrasonographic examination revealed inhomogenecity in 45 cases and this was accurate in 40 cases; in 3 cases ultrasonography gave a false positive result and in 2 cases the wrong meniscus was shown to be torn. The six cases with no findings on ultrasonography were proven to have no meniscal tear. The sensitivity of ultrasonography as a screening test to rule out meniscal injuries was thus 100%; on the other hand the specificity (false positive screening test) was 54%. It was no possible to determine the site, size or extent of the tear by the ultrasonographic examination. Even though magnetic resonance imaging is more accurate in giving an exact diagnosis, ultrasonography is an excellent primary diagnostic tool which is inexpensive with no side-effects, is readily available and has very good sensitivity and a reasonable specificity.

Therapeutic management strategies for type 2 diabetes

Diabetes mellitus type 1 and 2 affects people worldwide and is associated with further complications like macrovascular, microvascular and its effect is observed as retinopathy, cardiovascular diseases, nephropathy and many more diseases. There are numerous suggestions, treatments for presentation and controlling diabetes but no curative agents. Therefore the aim is to prevent or delay onset or control the complications. This work outlines the principle strategies for management of type 2 diabetes.

Recycling and utilization of metabolic wastes for energy production is an index of biochemical adaptation of fish under environmental pollution stress

The activity levels of lactate dehydrogenase and lactic acid were assessed in various tissues of the fish during exposure to lethal concentration of group-II Pyrethroids (deltamethrin, cypermethrin, fenvalerate and fluvalinate) for a period of 72 hours. The results showed steady increased levels in all the tissues (blood, muscle, brain and liver) with response pattern characteristic of their own. The increased LDH activity and lactic acid levels indicate the shifting of aerobic glycolysis to anaerobiosis and its further utilization for energy production during adaptation to toxic stress.

PHARMACOGNOSTIC STUDIES ON Sida acuta Burm.f

Sida acuta Burm.f. (Fam. Malvaceae) is used in Siddha system of medicine and in folk medical practice in Tamil Nadu under the names Arivalmooku pachilai or vattatiruppi. The leaves of this plant are used for their diuretic, demulcent, anthelmintic and wound healing properties. The present paper discusses the anatomy of petiole leaf and stem, microscopic constants, physico-chemical standards and fluorescence analysis of the drug.

Effect of pyrethroids on carbohydrate metabolic pathways in common carp, Cyprinus carpio

The activity levels of succinate dehydrogenase (SDH) and glucose-6-phosphate dehydrogenase (G6PD) were assessed in various tissues of Cyprinus carpio var communis which had been exposed to lethal concentrations of group-II pyrethroids (deltamethrin, cypermethrin, fenvalerate and fluvalinate) for a period of 72 h. The results indicated a steady decrease in SDH activity with a concomitant increase in G6PD activity. The decreased SDH activity indicated inhibition of SDH at mitochondrial level and the increased G6PD activity an enhancement of an alternative pathway of carbohydrate metabolism, viz the hexose monophosphate shunt (HMP) or pentose phosphate pathway as a biochemical adaptation to overcome the toxic stress.

Design, synthesis, and transfection biology of novel cationic glycolipids for use in liposomal gene delivery

The molecular structure of the cationic lipids used in gene transfection strongly influences their transfection efficiency. High transfection efficiencies of non-glycerol-based simple monocationic transfection lipids with hydroxyethyl headgroups recently reported by us (Banerjee et al. J. Med. Chem. 1999, 42, 4292-4299) are consistent with the earlier observations that the presence of hydroxyl functionalities in the headgroup region of a cationic lipid contributes favorably in liposomal gene delivery. Using simple sugar molecules as the source of multiple hydroxyl functionalities in the headgroup region of the transfection lipids, we have synthesized four novel simple monocationic transfection lipids, namely, 1-deoxy-1-[dihexadecyl(methyl)ammonio]-D-xylitol (1), 1-deoxy-1-[methyl(ditetradecyl)ammonio]-D-arabinitol (2), 1-deoxy-1-[dihexadecyl(methyl)ammonio]-D-arabinitol (3) and 1-deoxy-1-[methyl(dioctadecyl)ammonio]-D-arabinitol (4), containing hydrophobic aliphatic tails and the hydrophilic arabinosyl or xylose sugar groups linked directly to the positively charged nitrogen atom. Syntheses, chemical characterizations, and the transfection biology of these novel transfection lipids 1-4 are described in this paper. Lipid 1, the xylosyl derivative, showed maximum transfection on COS-1 cells. All the lipids showed transfection with cholesterol as colipid and not with dioleoylphosphatidylethanolamine (DOPE). Radioactive quantitation of free and complexed DNA combined with ethidium bromide exclusion measurements suggest that though nearly 70% of the DNA exists as complexed DNA, the DNA may not have condensed as was observed with other cationic lipids. Presence of additional (more than two) hydroxyl functionalities in the headgroup of the cationic lipids appears to have improved the transfection efficiency and made these lipids less cytotoxic compared to two-hydroxyl derivatives.

Scanning mutagenesis reveals roles for helix n of the bacteriophage T7 RNA polymerase thumb subdomain in transcription complex stability, pausing, and termination

Deletions within the thumb subdomain (residues 335-408) of T7 RNA polymerase decrease elongation complex stability and processivity, but the structure of a T7RNAP initial transcription complex containing a 3-nucleotide RNA reveals no interactions between the thumb and the RNA or DNA. Modeling of a longer RNA in this structure, using a T7DNAP-primer-template structure as a guide, suggests that the phosphate ribose backbone of the RNA contacts a stretch of mostly positively charged side chains between residues 385 and 395 of helix N of the thumb. Scanning mutagenesis of this region reveals that alanine substitutions of Arg(391), Ser(393), and Arg(394) destabilize elongation complexes and that substitutions at 393 and 394 increase termination of transcripts 5 or more bases in length. The alpha-carbons of all 3 of these residues lie on the side of helix N, which faces into the template-binding cleft of the RNA polymerase, and modeling suggests that they can contact the RNA 4-5 bases away from the 3'-end. Alanine substitutions of other residues within 385-395 do not have marked effects on transcription complex stability, but alanine substitutions of Asp(388) and Tyr(385) reduce pausing and termination at the T7 concatemer junction. Both of these side chains lie on the outer side of helix N, pointing away from the template binding cleft. The thumb subdomain of T7RNAP therefore has roles both in transcription complex stabilization and in pausing and termination at the T7 concatemer junction.

Small worlds: how and why

We investigate small-world networks from the point of view of their origin. While the characteristics of small-world networks are now fairly well understood, there is as yet no work on what drives the emergence of such a network architecture. In situations such as neural or transportation networks, where a physical distance between the nodes of the network exists, we study whether the small-world topology arises as a consequence of a tradeoff between maximal connectivity and minimal wiring. Using simulated annealing, we study the properties of a randomly rewired network as the relative tradeoff between wiring and connectivity is varied. When the network seeks to minimize wiring, a regular graph results. At the other extreme, when connectivity is maximized, a "random" network is obtained. In the intermediate regime, a small-world network is formed. However, unlike the model of Watts and Strogatz [Nature 393, 440 (1998)], we find an alternate route to small-world behavior through the formation of hubs, small clusters where one vertex is connected to a large number of neighbors.

Distribution of particulate matter and tissue remodeling in the human lung

We examined the relationship between intrapulmonary particle distribution of carbonaceous and mineral dusts and remodeling of the airways along anatomically distinct airway paths in the lungs of Hispanic males from the central valley of California. Lung autopsy specimens from the Fresno County Coroner's Office were prepared by intratracheal instillation of 2% glutaraldehyde at 30 cm H(2)O pressure. Two distinct airway paths into the apico-posterior and apico-anterior portions of the left upper lung lobe were followed. Tissue samples for histologic analysis were generally taken from the intrapulmonary second, fourth, sixth, and ninth airway generations. Parenchymal tissues beyond the 12th airway generation of each airway path were also analyzed. There was little evidence of visible particle accumulation in the larger conducting airways (generations 2-6), except in bronchial-associated lymphoid tissues and within peribronchial connective tissue. In contrast, terminal and respiratory bronchioles arising from each pathway revealed varying degrees of wall thickening and remodeling. Walls with marked thickening contained moderate to heavy amounts of carbonaceous and mineral dusts. Wall thickening was associated with increases in collagen and interstitial inflammatory cells, including dust-laden macrophages. These changes were significantly greater in first-generation respiratory bronchioles compared to second- and third-generation respiratory bronchioles. These findings suggest that accumulation of carbonaceous and mineral dust in the lungs is significantly affected by lung anatomy with the greatest retention in centers of lung acini. Furthermore, there is significant remodeling of this transitional zone in humans exposed to ambient particulate matter.

Characterization of structural features important for T7 RNAP elongation complex stability reveals competing complex conformations and a role for the non-template strand in RNA displacement

We have characterized the roles of the phage T7 RNA polymerase (RNAP) thumb subdomain and the RNA binding activity of the N-terminal domain in elongation complex (EC) stability by evaluating how disrupting these structures affects the dissociation rates of halted ECs. Our results reveal distinct roles for these elements in EC stabilization. On supercoiled or partially single-stranded templates the enzyme with a deletion of the thumb subdomain is exceptionally unstable. However, on linear duplex templates the polymerase which has been proteolytically cleaved within the N-terminal domain is the most unstable. The differences in the effects of these RNAP modifications on the stability of ECs on the different templates appear to be due to differences in EC structure: on the linear duplex templates the RNA is properly displaced from the DNA, but on the supercoiled or partially single-stranded templates an extended RNA:DNA hybrid makes a larger contribution to the conformational state of the EC. The halted EC can therefore exist either in a conformation in which the RNA is displaced from the DNA and forms an interaction with the RNAP, or in a conformation in which a more extended RNA:DNA hybrid is present and the RNA:RNAP interaction is less extensive. The partitioning between these competing conformations appears to be a function of the energetics of template reannealing and the relative strengths of the RNA:RNAP interaction and the RNA:DNA hybrid.

Mutations in the 1.1 subdomain of Escherichia coli sigma factor sigma70 and disruption of its overall structure

Among various group I sigma factors, two amino acids, Val55 and Ala59 are the conserved amino acids in the 1.1 hydrophobic subdomain. These two sites have been mutated to generate variants designated as [Gly55]sigma70 and [Gly59]sigma70, where glycine replaces valine and alanine, respectively. The function of these sigma mutants is reported here. The molecular mass of these proteins determined on denaturing gels was 70 kDa, which is the expected calculated molecular mass; wild-type sigma70 has an apparent molecular mass of 87 kDa. However, [Gly434]sigma70, which contains a mutation at the DNA-binding rpoD box region, also migrates as a 70-kDa protein on SDS/PAGE. Circular dichroism spectral analysis indicated that both [Gly55]sigma70 and [Gly59]sigma70 have reduced helicity (20%) compared to wild-type sigma70 (50%). Binding of sigma factors with the hydrophobic, surface active probe 1-anilinonapthalene-8-sulphonate, has shown that more hydrophobic surfaces are available/exposed in [Gly55]sigma70, [Gly59]sigma70 as well as in [Gly434]sigma70 in comparison to wild-type sigma70. Time-resolved emission spectroscopic studies have suggested transient binding between these mutants and DNA. The different holoenzyme RNA polymerases generated upon reconstituting these mutants independently with core RNA polymerase (alpha2beta beta') have shown reduced transcriptional activity in comparison to the enzyme containing wild-type sigma factor. However, another mutation (Val-->Gly) in the hydrophobic subdomain 1.2 at position 83, which is designated as [Gly83]sigma70, has similar properties as the wild-type with respect to its mobility on denaturing gels, circular dichroism profile, and transcriptional activity when reconstituted with core RNA polymerase. It appears that the 1.1 subdomain in sigma70 may interact hydrophobically with the 2.3/2.4 DNA-binding region.

Recognition of promoter DNA by subdomain 4.2 of Escherichia coli sigma 70: a knowledge based model of -35 hexamer interaction with 4.2 helix-turn-helix motif

In Escherichia coli, subdomains 2.4 and 4.2 of the primary transcription factor sigma 70 are the most highly conserved regions and are responsible for the recognition of -10 and -35 promoter elements respectively. Mutational studies provide evidence to this end and indicate that the side chains of subdomain 4.2 make specific contacts with the nucleotides at -35. Subdomain 4.2 is highly conserved among group-1 sigma factors and is strongly homologous to the classical helix-turn-helix (HTH) motif shared by bacteriophage lembda cl, Cro, the CAP protein and other homeodomain proteins, suggesting that sigma factor also belongs to the HTH class of proteins. In this study, a single point mutation of the conserved hydrophobic residue valine at position 576, in the 4.2 subdomain results in a mutant that is transcriptionally inefficient although conformationally similar to wild-type sigma. The mutant sigma, like wild-type, migrates as a 87 kDa protein on SDS gels and has 50% helicity. However, transcription at "extended -10 promoter' by RNA polymerase containing mutant sigma 70-V576G, synthesized appreciable amount of RNA product, when compared with that generated by sigma 70-W434G, a mutation in -10 DNA binding domain. A model of HTH motif for the conserved 20 residue region of 4.2 domain of E. coli sigma 70 as well as its mutant sigma 70-V576G and sigma 70-V576T were constructed based on five other homologous HTH motifs from DNA-protein complexes for which X-ray or NMR structure is available. A B-DNA structure was designed for -35 region using sequence dependent base pair parameters. The modeled HTH structure was docked into the major groove formed by the -35 hexamer DNA using the DNA-recognition rules and amino acid-nucleotide base contact information of homologous DNA-protein complexes. Analysis of the residue contact information of the model was tested and found to have good agreement with the experimental reports.

Time-resolved emission spectroscopy as a tool to follow nucleic acid-protein interaction

Fluorescence spectroscopy is undoubtedly a useful tool to study the structural and functional aspects of nucleic acids-protein interactions as well as the catalytic functions of particular residues of multi-subunit enzyme complexes. The dynamic interaction of nucleic acids and proteins occurring at nanosecond time scale can now be monitored by making life-time measurements or by time-resolved emission spectroscopy. These measurements are made by exploiting the intrinsic fluorescent residues in proteins i.e. W or by the use of extrinsic fluorophores which are tagged on to particular residues and that are sensitive to the microenvironment changes. In this study we describe the use of time resolved emission spectroscopy to (a) analyse the transient binding between sigma 70 and DNA by monitoring the quenching of W residues and (b) monitor the various states which nucleosomes of active, inducible or inactive chromatin may adopt in vivo.

Distribution of cell cycle times amongst the leukemia cells within individual patients with acute myelogenous leukemia

Seventeen patients with AML received infusions of BrdUrd to permit measurement of the cell parameters of leukemia cells in vivo. The range of S-phase times was measured by using a two color BrdUrd/Pl analysis to determine the range of BrdUrd incorporation into cells which had been in S-phase throughout the entire duration of BrdUrd administration. These data were, in turn, used to calculate the range of cell cycle times amongst the leukemia cells present within individual patients. The range of cell cycle times amongst the leukemia cells present within individual patients differs between patients, with some leukemia cell populations characterized by narrow and others by broad ranges. In general, the longer the mean cell cycle time (between 27 and 112 h) the broader the range of cell cycle times. These differences may help to explain, in part, the differences in response to therapy among patients whose mean leukemia cell kinetic parameters are similar.

A point mutation at the junction of domain 2.3/2.4 of transcription factor sigma 70 abrogates productive transcription and restores its expected mobility on a denaturing gel

Region 2 of eubacterial sigma factors is highly conserved and the subdomain 2.4 is involved in -10 promoter recognition. An evolutionary conserved "RpoD box" has been identified at the junction of subdomain 2.3/2.4 in class I and class II sigma factors and there are two tryptophan residues at position 433 and 434 which can be used as intrinsic fluorescent markers to study their structure-function relationship. Site-directed mutagenesis of these two tryptophan residues has been carried out to generate three variants of sigma 70 of Escherichia coli RNA polymerase. These are W433F, W433G and W434G. sigma 70-W433F is found to be indistinguishable from the native sigma factor by both structural and functional analysis. sigma 70-W433G shows anomalous mobility on SDS-PAGE like the native sigma factor, is alpha-helical in conformation (50% helicity) although found to be less active in total transcription when reconstituted with core RNA polymerase. Free sigma 70-W434G, unlike the native sigma factor, shows the expected mobility of a 70 kDa protein on SDS-PAGE and has 20% helicity. Time-resolved fluorescence analysis indicates that free sigma 70-W434G has DNA binding ability, and displays a normal abortive initiation reaction but a decreased level of productive transcription after reconstitution with core RNA polymerase. A model is proposed in which tryptophan at position 434 interacts with the hydrophobic 1.1 domain of sigma 70 giving rise to the stability of the protein under denaturing conditions.

Regrowth resistance in leukemia and lymphoma: the need for a new system to classify treatment failure and for new approaches to treatment

Treatment failure in drug sensitive malignancies is a complex phenomenon resulting from both drug resistance and from the rapid regrowth of malignant cells ('regrowth resistance'). Attempts to overcome regrowth resistance during the treatment of the aggressive lymphomas by increasing the frequency of cytotoxic therapy appears to have failed. An alternative approach of significant potential would be to administer biologically active agents to directly slow the regrowth of neoplastic cells between courses of full dose cytotoxic therapy. To facilitate this approach a new system for classifying treatment failure in the leukemias and lymphomas is needed so that the extent of regrowth resistance and the effects of treatment on regrowth resistance can be directly assessed. Accordingly, a new classification system is proposed.

The study of acute leukemia cells by means of acridine orange staining and flow cytometry

The studies described here explored the staining of acute leukemia cells with acridine orange (AO). The red fluorescence curve of AML specimens was usually bimodal, suggesting the presence of subpopulations of cells which have different RNA contents. In almost every AML specimen, small leukemic blast cells comprised at least part of the "low RNA content" subpopulation. Residual granulocytes and lymphocytes also contributed to this population. Frequently, the green fluorescence, indicative of the binding of AO to DNA, was slightly less in these cells than in the majority of cells present. There was no evidence however, that the leukemia cells with these characteristics represented a G0 or kinetically quiescent population of cells. In ALL specimens, the presence of multiple cytogenetically distinct clones was easily detectable in AO stained specimens. The red fluorescence curve of G0/G1 ALL cells was unimodal.

Effects of rhGM-CSF on myeloid clonogenic cells in acute myelogenous leukemia patients

The effects of rhGM-CSF in vivo on the myeloid clonogenic cells present in 6 AML patients was evaluated. The relative number of clonogenic cells fell in 4 of the 6 patients. The effects of rhGM-CSF on the percentage of clonogenic cells in S phase and the sensitivity of clonogenic cells to cytosine arabinoside varied among the patients. These effects were not related to the effects of rhGM-CSF on the white blood cell count or on the proliferative rate of the leukemia cell population as a whole.

Clonogenic potential of myeloid leukaemia cells in vitro is restricted to leukaemia cells expressing the CD34 antigen

Cells from patients with acute myeloid leukaemia (AML) or chronic myeloid leukaemia (CML) were separated into CD34-enriched and CD34-depleted subpopulations. The clonogenic capacities of these two subpopulations were then compared to each other and to the original unseparated cell population. In every study, the CD34-enriched subpopulation demonstrated a substantial increase in clonogenicity in vitro in comparison with the original cell population, while the reverse was the case for the CD34-depleted subpopulations. For reasons not clear at present, the enrichment for clonogenic cells far exceeded the enrichment for cells expressing the CD34 antigen. Additionally, the clonogenic potential was found to be unrelated to the level of myc expression in the various cell populations.

Comparison of two methods for concentrating CD34+ cells from patients with acute non-lymphocytic leukemia

The aim of the present study was to compare two different methods for obtaining CD34+ cells from the peripheral blood or the bone marrow of patients with acute non-lymphocytic leukemia (ANLL). Twenty-two samples, obtained from 19 patients, were density cut (Ficoll-Hypaque 1.077) and, after incubation with My10 antibody, separated by panning or by immunomagnetic beads. Immunomagnetic beads provided a significantly better separation than panning, either in terms of concentration of CD34+ cells (85.5 +/- 11.6% vs. 55.7 +/- 25.0%, p = 0.003) or in terms of depletion of CD34+ cells (3.9 +/- 8.0% vs. 30.9 +/- 26.3%, p = 0.008). This was consistent with the virtually complete depletion of colony forming cells (CFC) in the CD34 negative fraction and the recovery of virtually all the CFC in the positive fraction in the samples separated by immunomagnetic beads. In conclusion, separation by immunomagnetic beads can allow collection of nearly pure CD34+ and CD34- cell populations from patients with ANLL, thereby facilitating the study of the biological characteristics of these cell populations. Moreover the method is less time consuming than panning and is not toxic to the CFC.

c-myc and c-myb expression in acute myelogenous leukemia

Monoclonal antibodies and flow cytometry were used to detect the expression of c-myc and c-myb in the bone marrow (BM) and peripheral blood (PB) cells of patients with acute myelogenous leukemia (AML). The expression of neither gene was correlated with the percent blast cells in the BM or PB nor was there a correlation between c-myc and c-myb expression. A wide range of expression of each gene was found within each FAB type of AML. Patients who had a high proportion of leukemia cells expressing c-myb were less likely to respond to remission induction therapy than patients in whom a low proportion of cells expressed c-myb. This association appears to reflect an inverse relationship between the proportion of cells expressing c-myb and the sensitivity of leukemia cells to the killing effects of chemotherapy in vivo. Treatment outcome was unrelated to c-myc expression.

Abnormal regulation of the myc gene in myeloid leukemia

To study the regulation of expression of the myc protooncogene, cells from normal individuals and patients with acute myelogenous leukemia (AML), and chronic phase and blastic crisis of chronic myeloid leukemia (CML) cells were put in overnight culture in the presence or absence of fetal calf serum. Myc expression in normal marrow cells and chronic phase CML cells fell after culture in vitro. In contrast, myc expression was maintained or increased in a majority of the AML and blastic crisis CML specimens. These data demonstrate that the regulation of myc expression is disordered in many AML and blastic crisis specimens but not in chronic phase CML cells.

Effects of an IL-1 receptor antagonist on acute myeloid leukemia cells

The effect of an interleukin 1 receptor antagonist (IL-1ra) on the proliferation of acute myelogenous leukemia (AML) cells was investigated. The antagonist reduced the spontaneous clonogenicity of these cells as well as the clonogenicity of these cells subsequent to exposure to the antagonist. The effects of the IL-1ra on the clonogenicity of leukemia cells was observed even when the antagonist failed to inhibit DNA synthesis by the leukemia cell population as a whole. The data are consistent with the concept that the administration of IL-1ra subsequent to cytotoxic therapy has the potential of slowing the regrowth of leukemia cells thereby potentiating the effects of chemotherapy.