Using pluripotent stem cells to understand normal and leukemic hematopoietic development

Several decades have passed since the generation of the first embryonic stem cell (ESC) lines both in mice and in humans. Since then, stem cell biologists have tried to understand their potential biological and clinical uses for their implementation in regenerative medicine. The hematopoietic field was a pioneer in establishing the potential use for the development of blood cell products and clinical applications; however, early expectations have been truncated by the difficulty in generating bonafide hematopoietic stem cells (HSCs). Despite some progress in understanding the origin of HSCs during embryonic development, the reproduction of this process in vitro is still not possible, but the knowledge acquired in the embryo is slowly being implemented for mouse and human pluripotent stem cells (PSCs). In contrast, ESC-derived hematopoietic cells may recapitulate some leukemic transformation processes when exposed to oncogenic drivers. This would be especially useful to model prenatal leukemia development or other leukemia-predisposing syndromes, which are difficult to study. In this review, we will review the state of the art of the use of PSCs as a model for hematopoietic and leukemia development

Adsorption of CO on NaZSM-5 zeolite under moderate temperature and pressure conditions: an FTIR investigation

Adsorption of CO on NaZSM-5 zeolite was investigated at temperatures in the range 300-470 K and at pressures of 5-500 Torr using FTIR spectroscopy. The effect of exchanging the charge balancing cation in NaZSM-5 with a proton or calcium was evaluated. Data were also collected on NaY, CaY and CaX zeolites for comparison. We detected the development of six distinct CwO stretching bands with maxima at around 2111, 2130, 2146, 2160, 2176 and 2194 cm-1 during the adsorption of CO on NaZSM-5 zeolite at ambient temperatures. This was accompanied by the appearance of a prominent band at 2356 cm-1 and weak shoulder bands at frequencies around 2336, 2340, 2370 and 2380 cm-1 in the ν3 region of All the ν(CO) bands and CO2 . also the bands in the ν3 region of CO2 exhibited similar behaviour as a function of adsorbate pressure, evacuation, rise in sample temperature, and the exchange of charge balancing cation. For instance, the intensity of all the CwO stretching bands showed a similar growth behaviour with increasing adsorbate pressure, though the extent of this growth was di.erent for the individual IR bands. Similarly, these bands were removed simultaneously on evacuation. Furthermore, while all the vibrational bands in the v(CO) region showed a uniform isotopic shift corresponding to a frequency ratio ν(13C/12C) of ca. 0.977 and ν(18O/16O) of 0.976 for the adsorption of 13C16O and 12C18O, respectively, the bands in the ν3(CO2) region showed a red shift ?(13C/12C) of 0.972 with 13CO and an isotopic shift corresponding to 16O12C18O on 12C18O adsorption. No shift in ν(OH) bands was observed after CO adsorption under the conditions of this study. The results thus indicate that the individual zeolitic surface sites e.g., the Al3+ sites, Bronsted acid sites or the charge balancing cations, may not participate directly in the bonding of CO molecules at room temperature or above. Instead, the cage effect of zeolites plays an important role. The data are interpreted to suggest the formation of weakly bonded clusters of CO and CO2 molecules, occluded in the zeolitic cages and stabilized under the cationic field

On the catch of a juvenile whale shark Rhincodon typus Smith from Malabar Coast

On the 27th February 1963 a juvenile whale shark Rhincodon typus Smith was caught in a boat seine ' Paithu vala' operating in 12 fathom water off Cannanore coast. This shark, noted for its timidity and gentleness, did not make any attempt to struggle free from its captors and died soon, probably due to exhaustion or shock. It was towed to Thayyil landing centre where we had occasion to examine it

Optical diagnosis of cervical cancer by fluorescence spectroscopy technique

In the present work, we examine normal and malignant stage IIIB cervical tissue by laser induced fluorescence, with 2 different objectives. (i) Development of the fluorescence spectroscopy technique as a standard optical method for discrimination of normal and malignant tissue samples and, (ii) Optimization of the technique by the method of matching of a sample spectrum with calibration sets of spectra of pathologically certified samples. Laser-induced fluorescence spectra were measured using samples from 62 subjects at different excitation wavelengths. Principal component analysis (PCA) of spectra and intensity ratios of curve-resolved fluorescence peaks were tested for discrimination. It was found that PCA of total fluorescence at 325 nm excitation gives specificity and sensitivity over 95%. Use of calibration sets of spectra of histo-pathologically certified samples combined with PCA for matching and pass/fail classification of test samples is shown to have high sensitivity/specificity for routine diagnostic purposes as well as for possible staging of the disease. Further, the multi-component origin of the fluorescence spectra is illustrated by curve resolution and fluorescence spectra of separated proteins of tissue homogenates

Detonator using Nickel Hydrazine Nitrate as Primary Explosive

Nickel hydrazine nitrate is an energetic coordination compound having explosiveproperties in between that of primary and secondary. This compound was used to develop a newtype of detonator by replacing the sensitive primary explosive, lead azide in conventionaldetonators and keeping RDX (cyclotrimethylenetrinitramine) as the output secondary explosive.The detonator consists of three regions, viz., initiation, deflagration-to-detonation transition(DDT), and output. The initiation and the electrical rating of 1A/1W no-fire were achieved usinga suitable squib. The DDT and the output were taken care of, by pressing requisite quantitiesof Nickel hydrazine nitrate and RDX, respectively at required densities in a stainless steel stemchannel. The detonator assembly involves crimping the squib and the stem channel in a stainlesssteel housing and applying a suitable resin at the crimped-end for leak tightness. The outputwas assessed from the dent depth on aluminium plate, volume expansion on lead block, and byachieving veloctiy of detonation of 8200 m/s in mild detonating cords, containing 0.95 g/m ofRDX, which indicates full-order detonation. The detonators were tested at system level andfound to perform satisfactorily

The ascent of molecular cardiology

The techniques of molecular biology are increasingly employed to delineate the molecular basis of both normal and abnormal cardiovascular function. Thanks to the knowledge gained in these realms, remarkable progress has been made in recent years to understand the cellular and molecular mechanisms of diseases of the heart and blood vessels. Novel therapeutic options are also on the horizon. This article highlights the major advances made in the field of molecular cardiology

QENS and FTIR studies on binding states of benzene molecules adsorbed in zeolite HZSM-5 at room temperature

Fourier-transform infrared (FTIR) spectroscopy and quasi-elastic neutron scattering (QENS) were employed for monitoring of the binding states of benzene molecules, adsorbed in HZSM-5 zeolite at 300 K and for loadings of 0.6 to 7 molecules per unit cell. While the in-plane combination C-C and C-H stretching bands of adsorbed benzene remained una.ected, a splitting was observed in the out-of-plane C-H bending vibrational bands, a feature reported for the transformation of benzene from liquid to solid phase. Also, the intensity ratio of the in-plane C-C stretching band (ν19 of adsorbed benzene at 1479 cm-1 and the bands in the region ) 3100-3035 cm-1 due to fundamentals and combination C-C and C-H stretching vibrations indicated a trend observed typically for a condensed phase of benzene. No shift was observed in the frequency of the above-mentioned IR bands when zeolite samples exchanged with Na+ or Ca2+ were employed. QENS results suggest that the benzene molecules occluded in zeolitic pores (~3 molecules per unit cell) undergo a 6-fold rotation but their translation motion is too slow. Also, a high residence time of 16.5 ps was observed for the benzene entrapped in HZSM-5, compared to a time of ~2.5 ps reported for the liquid and ~19 ps for the solid state of benzene. These results reveal again the compression of the benzene molecules on adsorption in zeolitic pores. It is suggested that the benzene molecules confined in cavities experience a strong intermolecular interaction, giving rise eventually to their clustered state depending on the loading. In the clustered state, benzene molecules are packed with their plane parallel to zeolitic walls and interact with each other through p-electron clouds. No electronic bonding is envisaged between these clusters and the framework or the extra-framework zeolitic sites

Tweed in Martensites: A Potential New Spin Glass

We've been studying the ``tweed'' precursors above the martensitic transition in shape--memory alloys. These characteristic cross--hatched modulations occur for hundreds of degrees above the first--order shape--changing transition. Our two--dimensional model for this transition, in the limit of infinite elastic anisotropy, can be mapped onto a spin--glass Hamiltonian in a random field. We suggest that the tweed precursors are a direct analogy of the spin--glass phase. The tweed is intermediate between the high--temperature cubic phase and the low--temperature martensitic phase in the same way as the spin--glass phase can be intermediate between ferromagnet and antiferromagnet.Comment: 18 pages and four figures (included

Droplet Fluctuations in the Morphology and Kinetics of Martensites

We derive a coarse grained, free-energy functional which describes droplet configurations arising on nucleation of a product crystal within a parent. This involves a new `slow' vacancy mode that lives at the parent-product interface. A mode-coupling theory suggests that a {\it slow} quench from the parent phase produces an equilibrium product, while a {\it fast} quench produces a metastable martensite. In two dimensions, the martensite nuclei grow as `lens-shaped' strips having alternating twin domains, with well-defined front velocities. Several empirically known structural and kinetic relations drop out naturally from our theory.Comment: 4 pages, REVTEX, and 3 .eps figures, compressed and uuencoded, Submitted to Phys. Rev. Let