Biomedical subjects

S Bose

Publications and source records attributed to S Bose.

At least 37 records · Page 2Linked to original sources

PubMed2002

Generic entanglement generation, quantum statistics, and complementarity.

A general and an arbitrarily efficient scheme for entangling the spins (or any spinlike degree of freedom) of two independent uncorrelated identical particles by a combination of two particle interferometry and which way detection is formulated. It is shown that the same setup could be used to identify the quantum statistics of the incident particles from either the sign or the magnitude of measured spin correlations. Our setup also exhibits a curious complementarity between particle distinguishability and the amount of generated entanglement.

Journal Article↗

PubMed2002

Immunohistochemical localisation of nicotinic acetylcholine receptor subunits in human cerebellum.

Neuronal nicotinic acetylcholine receptors are members of the ligand-gated ion channel superfamily composed of alpha and beta subunits with specific structural, functional and pharmacological properties. In this study we have used immunohistochemistry to investigate the presence of nicotinic acetylcholine receptor subunits in human cerebellum. Tissue was obtained at autopsy from eight adult individuals (aged 36-56 years). Histological sections were prepared from formalin-fixed paraffin-embedded material. alpha 3, alpha 4, alpha 6, alpha 7, beta 2, and beta 4 subunits were present in this brain area associated with both neuronal and non-neuronal cell types. Most Purkinje cells were immunoreactive for all the above subunits, but most strongly for alpha 4 and alpha 7. A proportion of granule cell somata were immunoreactive for all subunits except alpha 3. Punctate immunoreactivity in Purkinje cell and granule cell layers was evident with antibodies against alpha 3, alpha 4, alpha 6, and alpha 7 in parallel with synaptophysin immunoreactivity, suggesting the presence of these subunits on nerve terminals in the human cerebellum. All subunits were present in the dentate nucleus associated with neurones and cell processes. Strong immunoreactivity of neuropil in both the molecular and granule cell layers and within the dentate nucleus was noted with alpha 4, alpha 7 and beta 4 subunits. Astrocytes and astrocytic cell processes appeared to be immunoreactive for alpha 7 and cell processes observed in white matter, also possibly astrocytic, were immunoreactive for beta2. Immunoreactivity to all subunits was noted in association with blood vessels. We suggest that nicotinic acetylcholine receptor subunits may be involved in the modulation of cerebellar activity. Further investigations are warranted to evaluate the participation of nicotinic acetylcholine receptors in cerebellar pathology associated with both developmental and age-related disorders.

Adult↗

PubMed2001

Impurity scattering induced entanglement of ballistic electrons.

We show how entanglement between two conduction electrons is generated in the presence of a localized magnetic impurity embedded in an otherwise ballistic conductor of special geometry. This process is a generalization of beam-splitter mediated entanglement generation schemes with a localized spin placed at the site of the beam splitter. Our entangling scheme is unconditional and robust to randomness of the initial state of the impurity. The entangled state generated manifests itself in noise reduction of spin-dependent currents.

Journal Article↗

PubMed2001

Teleportation as a depolarizing quantum channel, relative entropy, and classical capacity.

We show that standard teleportation with an arbitrary mixed state resource is equivalent to a generalized depolarizing channel with probabilities given by the maximally entangled components of the resource. This enables the usage of any quantum channel as a generalized depolarizing channel without additional twirling operations. It also provides a nontrivial upper bound on the entanglement of a class of mixed states. Our result allows a consistent and statistically motivated quantification of teleportation success in terms of the relative entropy and this quantification can be related to a classical capacity.

Journal Article↗

PubMed2001

Spatiotemporal dynamics near a supercritical Turing-Hopf bifurcation in a two-dimensional reaction-diffusion system.

Pattern formation in semiconductor heterostructures is studied on the basis of a spatially two-dimensional model of reaction-diffusion type. In particular, we investigate the neighborhood of a codimension-two Turing-Hopf instability by analytical methods. Amplitude equations are derived which predict the absence of mixed modes but extended ranges of bistability between homogeneous oscillatory states and hexagonal Turing patterns. Our results are confirmed by numerical simulations. The features are not confined to a neighborhood of the bifurcation point so that the conclusions of the weakly nonlinear analysis explain the observations in large portions of the parameter space at least qualitatively

Journal Article↗

PubMed2001

Subsystem purity as an enforcer of entanglement.

We show that entanglement can always arise in the interaction of an arbitrarily large system in any mixed state with a single qubit in a pure state. This small initial purity is enough to enforce entanglement even when the total entropy is close to maximum. We demonstrate this feature using the Jaynes-Cummings interaction of a two-level atom in a pure state with a field in a thermal state at an arbitrarily high temperature. We find the time and temperature variation of a lower bound on the amount of entanglement produced and study the classical correlations quantified by the mutual information.

Journal Article↗

PubMed2001

Electrically-assisted transdermal delivery of buprenorphine.

The objective of this study was to explore the electrically assisted transdermal delivery of buprenorphine. Oral delivery of buprenorphine, a synthetic opiate analgesic, is less efficient due to low absorption and large first-pass metabolism. While transdermal delivery of buprenorphine is expected to avoid the first-pass effect and thereby be more bioavailable, use of electrical enhancement techniques (iontophoresis and/or electroporation) could provide better programmability. Another use of buprenorphine is for opiate addiction therapy. However, a patch type device is subject to potential abuse as it could be removed by the addict. This abuse can be prevented if drug particles are embedded in the skin. The feasibility of doing so was investigated by electro-incorporation. Buprenorphine HCl (1 mg/ml) in citrate buffer (pH 4.0) was delivered in vitro across human epidermis via iontophoresis using a current density of 0.5 mA/cm(2) and silver-silver chloride electrodes. Electroporation pulses were also applied in some experiments. For electro-incorporation, drug microspheres or particles were driven into full thickness human skin by electroporation. It was observed that the passive transdermal flux of buprenorphine HCl was significantly enhanced by iontophoresis under anodic polarity. The effectiveness of electro-incorporation seemed inconclusive, with pressure also playing a potential role. Delivery was observed with electro-incorporation, but the results were statistically not different from the corresponding controls.

Administration, Cutaneous↗

PubMed2001

Natural thermal and magnetic entanglement in the 1D Heisenberg model.

We investigate the entanglement between any two spins in a one dimensional Heisenberg chain as a function of temperature and the external magnetic field. We find that the entanglement in an antiferromagnetic chain can be increased by increasing the temperature or the external field. Increasing the field can also create entanglement between otherwise disentangled spins. This entanglement can be confirmed by testing Bell's inequalities involving any two spins in the solid.

Journal Article↗

PubMed2001

A degradation signal located in the C-terminus of p21WAF1/CIP1 is a binding site for the C8 alpha-subunit of the 20S proteasome.

The cyclin-dependent kinase inhibitor p21WAF1/CIP1 is a key regulator of cell-cycle progression and its expression is tightly regulated at the level of transcription and by proteasome-dependent proteolysis. The turnover of p21WAF1/CIP1 by proteasomes does not always require the ubiquitylation of p21WAF1/CIP1 suggesting that there could be an alternative pathway into the proteasome. Here we show that the C8 alpha-subunit of the 20S proteasome interacts with the C-terminus of p21WAF1/CIP1 and mediates the degradation of p21WAF1/CIP1. A small deletion in this region that disrupts binding to C8 increased the half-life of p21WAF1/CIP1 expressed in vivo. In contrast a deletion that increased the affinity between C8 and p21WAF1/CIP1 significantly reduced the stability of the latter. These data suggest that interaction with a 20S proteasome alpha-subunit is a critical determinant of p21WAF1/CIP1 turn-over and show how non-ubiquitylated molecules might bypass the 19S regulator of the proteasome and become targeted directly to the 20S, core protease. Consistent with this, p21WAF1/CIP1 was degraded rapidly by purified 20S proteasomes in a manner that was dependent on the C8-interaction domain.

3T3 Cells↗

PubMed2001

gamma-Interferon decreases the level of 26 S proteasomes and changes the pattern of phosphorylation.

In mammalian cells proteasomes can be activated by two different types of regulatory complexes which bind to the ends of the proteasome cylinder. Addition of two 19 S (PA700; ATPase) complexes forms the 26 S proteasome, which is responsible for ATP-dependent non-lysosomal degradation of intracellular proteins, whereas 11 S complexes (PA28; REG) have been implicated in antigen processing. The PA28 complex is upregulated in response to gamma-interferon (gamma-IFN) as are three non-essential subunits of the 20 S proteasome. In the present study we have investigated the effects of gamma-IFN on the level of different proteasome complexes and on the phosphorylation of proteasome subunits. After treatment of cells with gamma-IFN, the level of 26 S proteasomes decreased and there was a concomitant increase in PA28-proteasome complexes. However, no free 19 S regulatory complexes were detected. The majority of the gamma-IFN-inducible proteasome subunits LMP2 and LMP7 were present in PA28-proteasome complexes, but these subunits were also found in 26 S proteasomes. The level of phosphorylation of both 20 S and 26 S proteasome subunits was found to decrease after gamma-IFN treatment of cells. The C8 alpha subunit showed more than a 50% decrease in phosphorylation, and the phosphorylation of C9 was only barely detectable after gamma-IFN treatment. These results suggest that association of regulatory components to 20 S proteasomes is regulated, and that phosphorylation of proteasome alpha subunits may be one mode of regulation.

Cell Line↗

PubMed2001

Tophaceous pseudogout: a pitfall in the diagnosis of chondrosarcoma.

Tumoral calcium pyrophosphate dihydrate deposition disease (TCPPD, tumoral or tophaceous pseudogout) is a rare nonneoplastic entity which mimics soft-tissue or skeletal malignancy. We present here the fine-needle aspiration cytology findings of a unique case of TCPPD in a 76-yr-old woman, with a large paraischial soft-tissue mass diagnosed as a malignant neoplasm. The difficulty in diagnosing such lesions by fine-needle aspirates is discussed and reviewed in the context of known cases from the literature.

Aged↗

PubMed2001

Cytologically benign endometrial cells in the papanicolaou smears of postmenopausal women.

OBJECTIVE: The objective of this study was to determine the clinical significance of the presence of benign endometrial cells in the Pap smears of postmenopausal women. METHODS: A retrospective analysis of the clinical outcome of 297 postmenopausal women containing benign endometrial cells in their Pap smears was performed. All patients had subsequent endometrial biopsies or routine follow-up for 1-5 years. In addition, Pap smears of 253 of the patients were reviewed with particular reference to the morphology and type of the endometrial cells. Immunohistochemical staining with CD68 was performed in 15 selected cases to determine the origin of the stromal cells. RESULTS: One hundred thirty-two (44%) women had endometrial biopsies while the remaining 165 (56%) were followed up by routine gynecologic examinations and repeat Pap smears. Endometrial lesions were detected in 14 patients of whom only 3 had significant lesions (2 atypical hyperplasias and 1 adenocarcinoma). Review of the Pap smears revealed benign superficial endometrial stromal cells in most cases (73%). Stromal cells showed CD68 positivity indicating a histiocytic origin. Glandular cells were present in 27%, either alone or in association with stromal cells. Statistical analysis revealed that the presence of endometrial glandular cells in Pap smears was associated with five times the likelihood of significant endometrial disease than found in women with normal Pap smears, although sensitivity and positive predictive value were very low (7.14 and 2.94%, respectively). Superficial endometrial stromal cells were not useful in predicting endometrial pathology. CONCLUSION: Significant endometrial lesions were present in 1% of postmenopausal women containing morphologically benign endometrial cells in the Pap smears. In the majority, the endometrial cells were of the superficial stromal type, which were demonstrated immunohistochemically to be histiocytes. The presence of endometrial glandular cells correlated significantly with endometrial pathology. Such an association was not observed in cases with stromal cells only.

Aged↗

PubMed2001

Epidemiology of gallstone disease in Chandigarh: a community-based study.

BACKGROUND: Cholelithiasis is frequent in our country (India), and is a common cause for abdominal surgery. We studied the prevalence of gallstone disease and its association with various risk factors in the city of Chandigarh. METHODS: A house-to-house survey of residents aged 15 years or above in a subsector of Chandigarh was conducted as a part of a pilot survey. All individuals with a history of gallstone disease, and equal or more number of asymptomatic individuals were asked to attend the outpatient department of the Postgraduate Medical Institute. On the basis of the pilot survey, the sample size to be studied was 2648 and we screened 2649 persons. RESULTS: Two hundred and fifty-four individuals attended the outpatient services of the Institute, and 248 underwent an ultrasound. There were 37 symptomatic and 211 asymptomatic individuals (male: female, 93:155). Gallstone disease was seen in 24 out of 37 (64.9%) in the symptomatic, and seven out of 211 (3.3%) in the asymptomatic group. Out of these, 27 females and four males had gallstone disease (mean age: 48.30 +/- 16.03 years). Approximately 67% of patients were between 20 and 60 years of age. Gallstone disease was more frequently seen in those from high socioeconomic status as compared to middle socioeconomic status (chi2 = 8.9, d.f. = 1, P < 0.01), and in multiparous as compared to nulliparous females (chi2 = 4.8, d.f. = 1, P < 0.05). Body mass index, smoking, alcohol consumption, and a vegetarian/non-vegetarian diet did not influence the prevalence of gallstone disease. CONCLUSIONS: Gallstone disease is frequent in northern India. Gallstones were frequent in those belonging to high socioeconomic status and multiparous females. However, body mass index, smoking, alcohol or other dietary habits did not make a difference.

Adolescent↗

PubMed2001

Polarity of human parainfluenza virus type 3 infection in polarized human lung epithelial A549 cells: role of microfilament and microtubule.

Human parainfluenza virus type 3 (HPIV-3) is an airborne pathogen that infects the epithelial cells of the respiratory tract. In the present study we investigated the interaction of HPIV-3 with the type II alveolar human lung polarized epithelial A549 cells. Although HPIV-3 entry and budding were bidirectional from both the apical and the basolateral domains, HPIV-3 exhibited preferential entry and release from the apical pole. While disruption of the cellular actin microfilament and microtubule by cytochalasin D and nocodazole, respectively, had no effect on virus entry, disruption of the microtubule but not the microfilament inhibited HPIV-3 release.

Actin Cytoskeleton↗

PubMed2000

Communication capacity of quantum computation.

By considering quantum computation as a communication process, we relate its efficiency to its classical communication capacity. This formalism allows us to derive lower bounds on the complexity of search algorithms in the most general context. It enables us to link the mixedness of a quantum computer to its efficiency and also allows us to derive the critical level of mixedness beyond which there is no quantum advantage in computation.

Journal Article↗

PubMed2000

Proposal for measurement of harmonic oscillator berry phase in ion traps

We propose a scheme for measuring the Berry phase in the vibrational degree of freedom of a trapped ion. Starting from the ion in a vibrational coherent state we show how to reverse the sign of the coherent state amplitude by using a purely geometric phase. This can then be detected through the internal degrees of freedom of the ion. Our method can be applied to preparation of entangled states of the ion and the vibrational mode.

Journal Article↗

PubMed2000

Perinuclear localization and insulin responsiveness of GLUT4 requires cytoskeletal integrity in 3T3-L1 adipocytes.

The GLUT4 glucose transporter resides mostly in perinuclear membranes in unstimulated 3T3-L1 adipocytes and is acutely translocated to the cell surface in response to insulin. Using a novel method to purify intracellular GLUT4-enriched membranes, we identified by mass spectrometry the intermediate filament protein vimentin and the microtubule protein alpha-tubulin as components of these membranes. Immunoelectron microscopy of the GLUT4-containing membranes also revealed their association with these cytoskeletal proteins. Disruption of intermediate filaments and microtubules in 3T3-L1 adipocytes by microinjection of a vimentin-derived peptide of the helix initiation 1A domain caused marked dispersion of perinuclear GLUT4 to peripheral regions of the cells. Inhibition of the microtubule-based motor dynein by brief cytoplasmic acidification of cultured adipocytes also dispersed perinuclear GLUT4 and inhibited insulin-stimulated GLUT4 translocation to the cell surface. Insulin sensitivity was restored as GLUT4 was again concentrated near the nucleus upon recovery of cells in physiological buffer. These data suggest that GLUT4 trafficking to perinuclear membranes of cultured adipocytes is directed by dynein and is required for optimal GLUT4 regulation by insulin.

3T3 Cells↗

PubMed2000

Immunohistochemical analysis of polycyclic aromatic hydrocarbon-DNA adducts in breast tumor tissue.

Environmental carcinogens may play a role in the etiology of breast cancer, but the extent of their contribution is not yet defined. The aims of this study were to determine whether polycyclic aromatic hydrocarbon (PAH)-DNA adducts could be detected in stored paraffin blocks of breast tumor tissue (n=147) with an immunoperoxidase technique and whether they correlated with smoking history and/or mutant p53 protein expression. There was no significant difference in mean relative nuclear staining intensity in non-smokers (444+/-90, n=75), ever smokers (435+/-91, n=72), and current smokers (456+/-98, n=35). In either current or ever smokers, PAH-DNA adducts were non-significantly elevated in those with greater compared with lower exposure in relation to age at started smoking, years of smoking, cigarettes per day, and pack years. DNA damage levels were not elevated in tissues with compared with those without mutant p53 protein expression. These data demonstrate that immunohistochemical methods can be used to monitor DNA damage levels in archived breast tissues.

Adult↗