Nuclear roles for non-lamin intermediate filament proteins

The nuclear-localized lamins have long been thought to be the only intermediate filaments (IFs) with an impact on the architecture, properties, and functions of the nucleus. Recent studies, however, uncovered significant roles for IFs other than lamins (here referred to as "non-lamin IFs") in regulating key properties of the nucleus in various cell types and biological settings. In the cytoplasm, IFs often occur in the perinuclear space where they contribute to local stiffness and impact the shape and/or the integrity of the nucleus, particularly in cells under stress. In addition, selective non-lamin IF proteins can occur inside the nucleus where they partake in fundamental processes including nuclear architecture and chromatin organization, regulation of gene expression, cell cycle progression, and the repair of DNA damage. This text reviews the evidence supporting a role for non-lamin IF proteins in regulating various properties of the nucleus and highlights opportunities for further study.

Proton and molecular permeation through the basal plane of monolayer graphene oxide

Two-dimensional (2D) materials offer a prospect of membranes that combine negligible gas permeability with high proton conductivity and could outperform the existing proton exchange membranes used in various applications including fuel cells. Graphene oxide (GO), a well-known 2D material, facilitates rapid proton transport along its basal plane but proton conductivity across it remains unknown. It is also often presumed that individual GO monolayers contain a large density of nanoscale pinholes that lead to considerable gas leakage across the GO basal plane. Here we show that relatively large, micrometer-scale areas of monolayer GO are impermeable to gases, including helium, while exhibiting proton conductivity through the basal plane which is nearly two orders of magnitude higher than that of graphene. These findings provide insights into the key properties of GO and demonstrate that chemical functionalization of 2D crystals can be utilized to enhance their proton transparency without compromising gas impermeability.

pH-dependent water permeability switching and its memory in MoS2 membranes

Intelligent transport of molecular species across different barriers is critical for various biological functions and is achieved through the unique properties of biological membranes1-4. Two essential features of intelligent transport are the ability to (1) adapt to different external and internal conditions and (2) memorize the previous state5. In biological systems, the most common form of such intelligence is expressed as hysteresis6. Despite numerous advances made over previous decades on smart membranes, it remains a challenge to create a synthetic membrane with stable hysteretic behaviour for molecular transport7-11. Here we demonstrate the memory effects and stimuli-regulated transport of molecules through an intelligent, phase-changing MoS2 membrane in response to external pH. We show that water and ion permeation through 1T' MoS2 membranes follows a pH-dependent hysteresis with a permeation rate that switches by a few orders of magnitude. We establish that this phenomenon is unique to the 1T' phase of MoS2, due to the presence of surface charge and exchangeable ions on the surface. We further demonstrate the potential application of this phenomenon in autonomous wound infection monitoring and pH-dependent nanofiltration. Our work deepens understanding of the mechanism of water transport at the nanoscale and opens an avenue for the development of intelligent membranes.

Revisiting the significance of keratin expression in complex epithelia

A large group of keratin genes (n=54 in the human genome) code for intermediate filament (IF)-forming proteins and show differential regulation in epithelial cells and tissues. Keratin expression can be highly informative about the type of epithelial tissue, differentiation status of constituent cells and biological context (e.g. normal versus diseased settings). The foundational principles underlying the use of keratin expression to gain insight about epithelial cells and tissues primarily originated in pioneering studies conducted in the 1980s. The recent emergence of single cell transcriptomics provides an opportunity to revisit these principles and gain new insight into epithelial biology. Re-analysis of single-cell RNAseq data collected from human and mouse skin has confirmed long-held views regarding the quantitative importance and pairwise regulation of specific keratin genes in keratinocytes of surface epithelia. Furthermore, such analyses confirm and extend the notion that changes in keratin gene expression occur gradually as progenitor keratinocytes commit to and undergo differentiation, and challenge the prevailing assumption that specific keratin combinations reflect a mitotic versus a post-mitotic differentiating state. Our findings provide a blueprint for similar analyses in other tissues, and warrant a more nuanced approach in the use of keratin genes as biomarkers in epithelia.

A role for keratin 17 during DNA damage response and tumor initiation

High levels of the intermediate filament protein keratin 17 (K17) are associated with poor prognoses for several human carcinomas. Studies in mouse models have shown that K17 expression is positively associated with growth, survival, and inflammation in skin and that lack of K17 delays onset of tumorigenesis. K17 occurs in the nucleus of human and mouse tumor keratinocytes where it impacts chromatin architecture, gene expression, and cell proliferation. We report here that K17 is induced following DNA damage and promotes keratinocyte survival. The presence of nuclear K17 is required at an early stage of the double-stranded break (DSB) arm of the DNA damage and repair (DDR) cascade, consistent with its ability to associate with key DDR effectors, including γ-H2A.X, 53BP1, and DNA-PKcs. Mice lacking K17 or with attenuated K17 nuclear import showed curtailed initiation in a two-step skin carcinogenesis paradigm. The impact of nuclear-localized K17 on DDR and cell survival provides a basis for the link between K17 induction and poor clinical outcomes for several human carcinomas.

Keratin 17 regulates nuclear morphology and chromatin organization

Keratin 17 (KRT17; K17), a non-lamin intermediate filament protein, was recently found to occur in the nucleus. We report here on K17-dependent differences in nuclear morphology, chromatin organization, and cell proliferation. Human tumor keratinocyte cell lines lacking K17 exhibit flatter nuclei relative to normal. Re-expression of wild-type K17, but not a mutant form lacking an intact nuclear localization signal (NLS), rescues nuclear morphology in KRT17-null cells. Analyses of primary cultures of skin keratinocytes from a mouse strain expressing K17 with a mutated NLS corroborated these findings. Proteomics screens identified K17-interacting nuclear proteins with known roles in gene expression, chromatin organization and RNA processing. Key histone modifications and LAP2β (an isoform encoded by TMPO) localization within the nucleus are altered in the absence of K17, correlating with decreased cell proliferation and suppression of GLI1 target genes. Nuclear K17 thus impacts nuclear morphology with an associated impact on chromatin organization, gene expression, and proliferation in epithelial cells.This article has an associated First Person interview with the first author of the paper.

A Study of Clinical Presentation and Correlative Histopathological Patterns in Renal Parenchymal Disease

Suspicion and subsequent detection of renal disease is by an assessment of the urinalysis and renal function in the clinical context. Our attempt in this study is to correlate initial presenting features of urinalysis and renal function to the final histopathological diagnosis. A retrospective analysis of 1059 native kidney biopsies performed from January 2002 to June 2015 at Amrita Institute of Medical Sciences was conducted. Correlative patterns between urinalysis, renal function, and final histopathological diagnosis were studied. Five hundred and eleven (48%) patients had nephrotic syndrome. Out of these, 193 (38%) had pure: nephrotic syndrome, 181 (35.8%) had associated microhematuria, 110 (21.7%) had microhematuria and renal failure, and 27 (5.3%) had only associated renal failure. Minimal change disease (MCD) (30%), membranous nephropathy (30%), and IgA nephropathy (29%) were the major diseases in the respective groups. Five hundred and five (47.6%) patients had subnephrotic proteinuria. Out of these, 29 (5.6%) had only subnephrotic proteinuria, 134 (27%) had additional microhematuria, 300 (59%) had subnephrotic proteinuria, microhematuria, and renal failure, and 42 (8%) had subnephrotic proteinuria with renal failure. Lupus Nephritis (45% and 40%) and IgA Nephropathy (32% and 21%) were the major disorders in the subgroups respectively. Forty-two patients (3.7%) were biopsied for isolated renal failure with bland urinary sediment. Cast nephropathy and acute interstitial nephritis were the major diseases. Out of 89 patients with diabetes who were biopsied, 15 (16.8%) had diabetic nephropathy, 45 (50.5%) had no diabetic nephropathy, and 29 (32.5%) had diabetic nephropathy along with a non-diabetic renal disease. Postinfectious glomerulonephritis was the major glomerular disease. IgA nephropathy (22.2%) and membranous nephropathy (15.5%) were the major diseases in patients with diabetes with no diabetic nephropathy. In our population, MCD and membranous nephropathy formed the majority of diseases in biopsied nephrotic syndrome. Added microhematuria did not seem to decrease the incidence of either disease on the whole. We found a significant number of patients with membranous nephropathy with nephrotic syndrome, microhematuria, and additional renal failure. IgA nephropathy formed a majority of cases with nephrotic syndrome, microhematuria, and renal failure. The presence of renal failure regardless of other abnormalities in urinalysis showed a trend toward IgA nephropathy. Membranous nephropathy may have a more varied presentation than was originally thought and IgA nephropathy presenting as nephrotic syndrome may not be uncommon. MCD is the major subgroup of diseases in the pediatric population and presents both as nephrotic syndrome as well as nephrotic syndrome with microhematuria. Thus, urinalysis and renal failure may be a valuable tool in assessing renal disease.

Ultrathin graphene-based membrane with precise molecular sieving and ultrafast solvent permeation

Graphene oxide (GO) membranes continue to attract intense interest due to their unique molecular sieving properties combined with fast permeation. However, their use is limited to aqueous solutions because GO membranes appear impermeable to organic solvents, a phenomenon not yet fully understood. Here, we report efficient and fast filtration of organic solutions through GO laminates containing smooth two-dimensional (2D) capillaries made from large (10-20 μm) flakes. Without modification of sieving characteristics, these membranes can be made exceptionally thin, down to ∼10 nm, which translates into fast water and organic solvent permeation. We attribute organic solvent permeation and sieving properties to randomly distributed pinholes interconnected by short graphene channels with a width of 1 nm. With increasing membrane thickness, organic solvent permeation rates decay exponentially but water continues to permeate quickly, in agreement with previous reports. The potential of ultrathin GO laminates for organic solvent nanofiltration is demonstrated by showing >99.9% rejection of small molecular weight organic dyes dissolved in methanol. Our work significantly expands possibilities for the use of GO membranes in purification and filtration technologies.

Stimuli-responsive colorimetric and NIR fluorescence combination probe for selective reporting of cellular hydrogen peroxide

Hydrogen peroxide (H2O2) is a key reactive oxygen species and a messenger in cellular signal transduction apart from playing a vital role in many biological processes in living organisms. In this article, we present phenyl boronic acid-functionalized quinone-cyanine (QCy-BA) in combination with AT-rich DNA (exogenous or endogenous cellular DNA), i.e., QCy-BA⊂DNA as a stimuli-responsive NIR fluorescence probe for measuring in vitro levels of H2O2. In response to cellular H2O2 stimulus, QCy-BA converts into QCy-DT, a one-donor-two-acceptor (D2A) system that exhibits switch-on NIR fluorescence upon binding to the DNA minor groove. Fluorescence studies on the combination probe QCy-BA⊂DNA showed strong NIR fluorescence selectively in the presence of H2O2. Furthermore, glucose oxidase (GOx) assay confirmed the high efficiency of the combination probe QCy-BA⊂DNA for probing H2O2 generated in situ through GOx-mediated glucose oxidation. Quantitative analysis through fluorescence plate reader, flow cytometry and live imaging approaches showed that QCy-BA is a promising probe to detect the normal as well as elevated levels of H2O2 produced by EGF/Nox pathways and post-genotoxic stress in both primary and senescent cells. Overall, QCy-BA, in combination with exogenous or cellular DNA, is a versatile probe to quantify and image H2O2 in normal and disease-associated cells.

A molecular beacon-based DNA switch for reversible pH sensing in vesicles and live cells

The DNA switch based on a molecular beacon (closed state) to A-motif (open state) structural transformation is developed as an efficient and reversible pH sensor in synthetic vesicles and live cells.

Probing Photoexcited Carriers in a Few-Layer MoS2 Laminate by Time-Resolved Optical Pump-Terahertz Probe Spectroscopy

We report the dynamics of photoinduced carriers in a free-standing MoS2 laminate consisting of a few layers (1-6 layers) using time-resolved optical pump-terahertz probe spectroscopy. Upon photoexcitation with the 800 nm pump pulse, the terahertz conductivity increases due to absorption by the photoinduced charge carriers. The relaxation of the non-equilibrium carriers shows fast as well as slow decay channels, analyzed using a rate equation model incorporating defect-assisted Auger scattering of photoexcited electrons, holes, and excitons. The fast relaxation time occurs due to the capture of electrons and holes by defects via Auger processes, resulting in nonradiative recombination. The slower relaxation arises since the excitons are bound to the defects, preventing the defect-assisted Auger recombination of the electrons and the holes. Our results provide a comprehensive understanding of the non-equilibrium carrier kinetics in a system of unscreened Coulomb interactions, where defect-assisted Auger processes dominate and should be applicable to other 2D systems.

Engineering optical properties of a graphene oxide metamaterial assembled in microfluidic channels

The dense packing of two dimensional flakes by van der Waals forces has enabled the creation of new metamaterials with desirable optical properties. Here we assemble graphene oxide sheets into a three dimensional metamaterial using a microfluidic technique and confirm their ordering via measurements of ellipsometric parameters, polarized optical microscopy, polarized transmission spectroscopy, infrared spectroscopy and scanning electron microscopy. We show that the produced metamaterials demonstrate strong in-plane optical anisotropy (Δn≈0.3 at n≈1.5-1.8) combined with low absorption (k<0.1) and compare them with as-synthesized samples of graphene oxide paper. Our results pave the way for engineered birefringent metamaterials on the basis of two dimensional atomic crystals including graphene and its derivatives.

Temporally distinct roles of ATM and ROS in genotoxic-stress-dependent induction and maintenance of cellular senescence

Cells exposed to genotoxic stress induce cellular senescence through a DNA damage response (DDR) pathway regulated by ATM kinase and reactive oxygen species (ROS). Here, we show that the regulatory roles for ATM kinase and ROS differ during induction and maintenance of cellular senescence. Cells treated with different genotoxic agents were analyzed using specific pathway markers and inhibitors to determine that ATM kinase activation is directly proportional to the dose of the genotoxic stress and that senescence initiation is not dependent on ROS or the p53 status of cells. Cells in which ROS was quenched still activated ATM and initiated the DDR when insulted, and progressed normally to senescence. By contrast, maintenance of a viable senescent state required the presence of ROS as well as activated ATM. Inhibition or removal of either of the components caused cell death in senescent cells, through a deregulated ATM–ROS axis. Overall, our work demonstrates existence of an intricate temporal hierarchy between genotoxic stress, DDR and ROS in cellular senescence. Our model reports the existence of different stages of cellular senescence with distinct regulatory networks.

Impermeable barrier films and protective coatings based on reduced graphene oxide

Flexible barrier films preventing permeation of gases and moistures are important for many industries ranging from food to medical and from chemical to electronic. From this perspective, graphene has recently attracted particular interest because its defect-free monolayers are impermeable to all atoms and molecules. However, it has been proved to be challenging to develop large-area defectless graphene films suitable for industrial use. Here we report barrier properties of multilayer graphitic films made by gentle chemical reduction of graphene oxide laminates with hydroiodic and ascorbic acids. They are found to be highly impermeable to all gases, liquids and aggressive chemicals including, for example, hydrofluoric acid. The exceptional barrier properties are attributed to a high degree of graphitization of the laminates and little structural damage during reduction. This work indicates a close prospect of graphene-based flexible and inert barriers and protective coatings, which can be of interest for numerous applications.

Thyrocervical artery - jugular fistula following internal jugular venous catheterization

Arteriovenous fistula (AVF) is an anomalous communication between an artery and a vein, caused by an iatrogenic or traumatic etiology. Surgically created upper limb AVF remains the preferred vascular access for patients on maintenance hemodialysis. Nonetheless central vein cannulation for hemodialysis is a common procedure done in patients who need hemodialysis. We incidentally detected a thyrocervical artery - jugular fistula in a patient on maintenance hemodialysis. He underwent a successful intra arterial coil embolization of the feeding vessel. Review of literature has shown that, a thyrocervical artery - internal jugular vein arteriovenous fistula following a central venous catheterization has not been reported so far.

Takayasu arteritis in an infant

Takayasu arteritis (TA), a chronic inflammatory arteritis affecting the aorta and its main branches, is a rare condition mainly affecting young women in the second and third decades of life. Occurrence of TA in infants is extremely rare, with only less than 10 cases reported all over the world until date. We report a case of a 2-year-old girl who presented with hypertension and was diagnosed to have TA with bilateral renal artery stenosis and this is probably the youngest case reported from India.

Association of Interleukin 1 beta (IL-1B) gene polymorphism with early pregnancy loss risk in the North Indian population

C+3953T IL-1 B single-nucleotide polymorphism (SNP) genotyping was carried out in 140 unrelated early pregnancy loss (EPL) patients and in 198 fertile healthy control women and in chorionic villous samples by PCR-RFLP. In Indian population, this is the first report on association of IL-1 B SNP C+3953T polymorphism and EPL.

Single-layer behavior and its breakdown in twisted graphene layers

We report high magnetic field scanning tunneling microscopy and Landau level spectroscopy of twisted graphene layers grown by chemical vapor deposition. For twist angles exceeding ~3° the low energy carriers exhibit Landau level spectra characteristic of massless Dirac fermions. Above 20° the layers effectively decouple and the electronic properties are indistinguishable from those in single-layer graphene, while for smaller angles we observe a slowdown of the carrier velocity which is strongly angle dependent. At the smallest angles the spectra are dominated by twist-induced van Hove singularities and the Dirac fermions eventually become localized. An unexpected electron-hole asymmetry is observed which is substantially larger than the asymmetry in either single or untwisted bilayer graphene.

Limits on intrinsic magnetism in graphene

We have studied magnetization of graphene nanocrystals obtained by sonic exfoliation of graphite. No ferromagnetism is detected at any temperature down to 2 K. Neither do we find strong paramagnetism expected due to the massive amount of edge defects. Rather, graphene is strongly diamagnetic, similar to graphite. Our nanocrystals exhibit only a weak paramagnetic contribution noticeable below 50 K. The measurements yield a single species of defects responsible for the paramagnetism, with approximately one magnetic moment per typical graphene crystallite.

On resonant scatterers as a factor limiting carrier mobility in graphene

We show that graphene deposited on a substrate has a non-negligible density of atomic scale defects. This is evidenced by a previously unnoticed D peak in the Raman spectra with intensity of ∼1% with respect to the G peak. We evaluated the effect of such impurities on electron transport by mimicking them with hydrogen adsorbates and measuring the induced changes in both mobility and Raman intensity. If the intervalley scatterers responsible for the D peak are monovalent, their concentration is sufficient to account for the limited mobilities currently achievable in graphene on a substrate.

Making graphene luminescent by oxygen plasma treatment

We show that strong photoluminescence (PL) can be induced in single-layer graphene using an oxygen plasma treatment. The PL is spatially uniform across the flakes and connected to elastic scattering spectra distinctly different from those of gapless pristine graphene. Oxygen plasma can be used to selectively convert the topmost layer when multilayer samples are treated.

Control of graphene's properties by reversible hydrogenation: evidence for graphane

Although graphite is known as one of the most chemically inert materials, we have found that graphene, a single atomic plane of graphite, can react with atomic hydrogen, which transforms this highly conductive zero-overlap semimetal into an insulator. Transmission electron microscopy reveals that the obtained graphene derivative (graphane) is crystalline and retains the hexagonal lattice, but its period becomes markedly shorter than that of graphene. The reaction with hydrogen is reversible, so that the original metallic state, the lattice spacing, and even the quantum Hall effect can be restored by annealing. Our work illustrates the concept of graphene as a robust atomic-scale scaffold on the basis of which new two-dimensional crystals with designed electronic and other properties can be created by attaching other atoms and molecules.

Obstructive uropathy secondary to parametrial metastasis: an unusual presentation of breast carcinoma

BACKGROUND

Metastasis to the cervix and parametrium from breast carcinoma is a rare occurrence.

CASE REPORT

A 74-year-old woman presented to the urologists with loin pain and microscopic haematuria. Investigations revealed a right ureteric obstruction which was diagnosed to be secondary to parametrial metastasis from an unknown primary. Immunohistochemical studies revealed it to be originating from the breast. Occult breast carcinoma was then diagnosed by breast biopsy.

CONCLUSION

Obstructive uropathy secondary to parametrial metastasis is an unusual first presentation of breast carcinoma.

Expression cloning of novel regulators of 92 kDa type IV collagenase expression

Overexpression of the 92 kDa type IV collagenase (MMP-9) contributes to cancer progression. However, to date, there are few known regulators of expression of this metalloproteinase. We employed an expression library comprising 500,000 cDNA clones to screen for novel regulators of MMP-9 expression. HT1080 cells were transiently co-transfected with an MMP-9 promoter-luciferase reporter and pools of the cDNA expression library. Positive-scoring pools were subdivided in secondary and tertiary screens, after which the regulatory cDNAs were identified by DNA sequencing. This brief review illustrates the utility of expression cloning in identifying specific regulators of MMP-9 expression.

Invasive aspergillosis producing painful ophthalmoplegia

Painful ophthalmoplegia is caused by the lesions of orbital apex and anterior cavernous sinus. Cavernous sinus syndrome can be produced by intracranial invasive aspergillosis. A case of painful ophthalmoplegia due to invasive aspergillosis caused by Aspergillus niger in a diabetic patient is presented.

Age-dependent variation in contractility of adult cardiac myocytes

This study was designed to examine the influence of the age of adults on the contractile characteristics of the myocardium and to ascertain whether the age dependent variation is related to variation in sarcolemmal calcium channels. Cardiomyocytes were isolated from 2, 6 and 12-month-old, male Sprague-Dawley rats and the extent and velocity of contraction were recorded as a function of change in cell length. Age dependent increase in cell length and sarcomere length was significant (P<0.05). Extent of contraction increased with age and the velocities of contraction and relaxation normalized to total contraction decreased with age (P<0.05). Sensitivity to the L-type channel antagonist (verapamil, 1 microM) and the T-type channel antagonist (nickel chloride, 40 microM) was significant in 6 and 12-month-old animals. This differential response to calcium channel antagonists suggests that the age-dependent variation in contractility may be mediated by the variation in the distribution/function of sarcolemmal calcium channels.

Superoxide anions mediate proliferative response in cardiac fibroblasts

The study was undertaken to examine whether superoxide anions mediate a proliferative response in cardiac fibroblasts. Cardiac fibroblasts isolated from newborn Wistar rats were exposed to superoxide anion generating system (hypoxanthine + xanthine oxidase) and its effect on cell growth was assessed. A stimulatory response on fibroblast proliferation was observed. The proportion of proliferating cells increased within 3 h of treatment compared to the control and the cell density after 96 h of exposure remained significantly high (P < 0.0005). Inclusion of antioxidants neutralised the stimulatory response, fortifying the role of superoxide anions in cell proliferation. This observation indicates that superoxide anions can mediate a fibrotic reaction in the cardiac tissue.

Alteration in cardiomyocyte mechanics by suboptimal levels of extracellular magnesium

The beneficial effects of magnesium supplementation in pathological situations is well known, but the myocardial response to a nominal decrease in the level of magnesium has received relatively little attention. Hypomagnesemia can occur as chronic or acute manifestation of physiological changes, pathological conditions, or pharmacological interventions. Experimental interest was focused on the mechanical changes in adult rat heart myocytes following variation in extracellular Mg2+. Isolated cells were exposed to different levels of extracellular Mg2+ and the amplitude and rate of contraction were measured as a function of change in cell length using a video-based edge-detection system. Investigations have revealed that variation in the level of Mg2+ within physiological limits leads to mechanical changes. A decrease in the level of extracellular Mg2+ was accompanied by a significant increase in contractile amplitude and decrease in the velocities of contraction and relaxation. The contractile amplitude measured as percentage shortening were 3.08+/-0.19%, 4.62+/-0.19% and 6.9+/-0.40%, respectively, on exposure to 1.8, 0.8, and 0.48 mM Mg, and the corresponding velocities of contraction and relaxation normalized to amplitude were 0.54+/-0.02, 0.40+/-0.03, 0.31+/-0.03 and 0.47+/-0.02, 0.35+/-0.02, 0.24+/-0.02. The variations in contractile parameters associated with the change in the level of Mg were statistically significant (p < 0.01). Variation in the contractile properties associated with change in extracellular Mg2+ may be effected by alteration in Ca2+ transients.

Stimulation of cardiac fibroblast proliferation by cerium: a superoxide anion-mediated response

Cardiac fibroblasts play a multifarious role in the maintenance of the functional and structural integrity of the heart. Therefore inadvertent proliferation of these fibroblasts can affect the normal functioning of the heart. The proliferation of fibroblasts could be due to various factors. We have worked on the hypothesis that low levels of cerium may stimulate cardiac fibroblasts to undergo proliferation and that free radicals act as the mediators of the stimulatory response. Cardiac fibroblasts isolated from neonatal Wistar rats were cultured. Proliferation of the cells was measured by cell count and immunohistochemical visualization for proliferating cell nuclear antigen. The response to cerium was assessed by comparison with control. A stimulatory response at low levels of cerium was observed with a peak at 0.5 micrometer concentration of cerium. A concomitant increase in the generation of free radicals was also seen. The cerium-stimulated cell proliferation and free radical generation was neutralized by the inclusion of superoxide dismutase in the culture medium.

CONCLUSION

Low doses of cerium, at levels comparable to those found in the serum of patients with EMF, has a stimulatory effect on cardiac fibroblasts and the abrogation of proliferation by antioxidant superoxide dismutase indicates that superoxide anion acts as a biological intermediate in cerium-induced cardiac fibroblast proliferation.

Selective use of calcium chelators enhances the yield of calcium-tolerant myocytes from adult heart

Isolation of viable and functional cells from adult heart remains an intriguing problem for investigators who choose to use the cardiomyocyte model for experimental studies. With a few modifications of the existing procedures we have been able to improve the yield of ventricular myocardial cells from the adult rat heart. Sarcolemmal damage leading to hypercontracture due to Ca2+ loading appears to be the major hindrance to the successful isolation of sufficient number of viable cells. The two crucial steps are found to be the pre-enzymatic perfusion for Ca(2+)-depletion and the final step of Ca(2+)-repletion in extracellular medium for the isolation of Ca(2+)-tolerant myocytes. Inclusion of EGTA and taurine during the initial perfusion of Ca(2+)-free medium and of trypsin during reintroduction of Ca2+ led to a considerable increase in the yield of Ca(2+)-tolerant myocytes. The contraction amplitude and speed of shortening and relaxation of isolated cells were measured using an edge detection device. Selective use of calcium ion chelators appears to have a beneficial effect on the isolation of Ca(2+)-tolerant myocytes.

Magnesium levels in serum and erythrocytes of children from Kerala

BACKGROUND

Magnesium is required in higher quantities, during the phase of rapid growth, in children. Its level in the ground water in Kerala is low. This can cause magnesium deficiency especially in children from the lower socio-economic groups who also suffer from nutritional insufficiency.

METHODS

We compared the serum and erythrocyte magnesium levels of school children from high and low (agricultural labourers and fisherfolk) socio-economic groups. These levels were determined using atomic absorption spectrophotometry. Body mass indices and haemoglobin levels were used as indirect measures of nutritional status.

RESULTS

Serum and erythrocyte magnesium levels were significantly lower in both boys and girls from low socio-economic groups who also had lower body mass indices.

CONCLUSION

Nutritional insufficiency is prevalent in children from the low socio-economic groups and is associated with low serum and erythrocyte magnesium levels.

Paradoxical effect of cerium on collagen synthesis in cardiac fibroblasts

The present study examined the effect of cerium on collagen synthesis in cultured cardiac fibroblasts and explants. At 100 nM, a concentration comparable with that found in the cardiac tissue of patients with endomyocardial fibrosis, the element was found to enhance the incorporation of tritiated proline into collagen and non-collagen proteins while at 10 microM, it had an inhibitory effect. Cerium was found to have no effect on rates of DNA synthesis in fibroblasts at 100 nM. However, at this concentration, the element markedly enhanced the incorporation of tritiated uridine into RNA, suggesting that cerium may act at the level of transcription to stimulate collagen and non-collagen protein syntheses. The stimulatory action of very low levels of cerium on collagen synthesis may contribute to the accumulation of collagen seen in endomyocardial fibrosis.

Cerium depresses protein synthesis in cultured cardiac myocytes and lung fibroblasts

The present study examined the effect of Cerium on protein synthesis in cultured cardiac myocytes and lung fibroblasts exposed to normal and markedly subnormal levels of Mg2+. Cerium was found to have a general inhibitory effect on protein synthesis in these cell types, including the synthesis of myofibrillar proteins in the cardiac myocytes. Further, the effect of the metal ion was more pronounced in cells exposed to the Mg2(+)-deficient medium. The possible implications of the observations are discussed.

A simplified method for culture of human fetal heart tissue

Human fetal heart tissue obtained consequent to suction termination of pregnancy between 6 and 12 weeks of gestation were cultured as explants and maintained in a viable state, with spontaneous contractions up to 75 days. Ultrastructural morphology of the explant revealed that the cells remained healthy up to 21 days in culture. The model can therefore be used for experimental studies during the first 3 weeks in culture.

Synthetic hydrogel microspheres as substrata for cell adhesion and growth

Cross-linked poly(methyl methacrylate) (PMMA) microspheres were subjected to alkaline hydrolysis to obtain hydrophilic microspheres having carboxyl residues distributed throughout the matrix. These microspheres were found to support the growth of human skin fibroblasts and human heart and lung cells. Further, fibroblasts grown on them were found to be comparable with those grown on the commercial tissue culture plate with respect to [14C]amino acid uptake and incorporation into proteins. The hydrolyzed PMMA microspheres may find application as a microcarrier for cell culture.

The effects of aminoethyl phosphonic acid on hepatic microsomal drug metabolism and ultrastructure of normal and cholesterol fed rats

The effects of parenteral administration of aminoethyl phosphonic acid (AEP) on the liver microsomal drug metabolism and ultrastructure were studied in normal and 1% cholesterol-fed albino rats. AEP administration to rats fed a stock-diet resulted in decreased demethylation of aminopyrine with a concomitant fall in cytochrome P-450 level. Aniline hydroxylation remained unaltered. AEP injection to cholesterol-fed rats, caused marked reduction in both aminopyrine demethylation and aniline hydroxylation, with a significant increase in cytochrome P-450 level. AEP injection to both control and cholesterol-fed animals produced a modest increase in Bilirubin UDP-glucuronyl transferase. RNA:DNA ratio showed remarkable elevation in rats fed the cholesterol diet with AEP injection. AEP injection caused an atypical smooth endoplasmic reticulum and a marked loss of nuclear euchromatin. Effect of AEP was more pronounced in rats receiving the cholesterol-diet. AEP administration thus induces structural and drug metabolic enzyme alteration in liver.

Nasotracheal intubation in diphtheria

Nasotracheal intubation can be used effectively for the relief of upper airway obstruction in diphtheria. It has many advantages over tracheostomy; it avoids an operation and it eases anxiety of the parents. Of 57 patients so treated, 50 recovered without injury to the larynx in any patient.