A direct sensitivity matrix approach for fast reconstruction in electrical impedance tomography

In electrical impedance imaging, several proposed reconstruction algorithms have employed the concept of a sensitivity matrix, which can be used to relate the magnitude of a boundary voltage change of a 2D object to the change in conductivity inside the object that has given rise to it. The search for an appropriate inversion of the sensitivity matrix is the key to these algorithms. In this work, a method called the direct sensitivity matrix (DSM) approach for fast image reconstruction is proposed. Both theoretical and experimental results showing the efficiency of this proposed method are also presented.

Comparing ethnic group-specific DAI equations with the standard DAI

The Standard DAI is an orthodontic index based on public perceptions of dental aesthetics in the USA and is a regression equation linking the relative social acceptability of dental appearance and the objective, physical measurements of ten occlusal traits. It can be used in surveys of need for orthodontic treatment and as a screening tool in public programmes providing orthodontic care. To determine if the Standard DAI could be used internationally, 200 stimuli (photographs of dental configurations) were rated for dental aesthetics by 413 Chinese students, 418 Latvian students and 428 Native Americans. To develop ethnic group-specific DAI equations these ratings were linked by regression procedures to the occlusal trait measurements available for each of the 200 stimuli. Using these equations, group-specific DAI scores were calculated for the 200 stimuli. At all levels on the DAI scale the percentage agreements, sensitivities and specificities ranged from 73 to 100 per cent indicating that the Standard DA can be used without modification to calculate DAI scores among Chinese, Latvians and Native Americans.

Clinical observation of treatment of hypertension with calcium

The effect of oral calcium supplementation (1000 mg/day) on hypertension was studied in 57 borderline and mild-to-moderate hypertensive patients in a randomized, double-blind, placebo-controlled study for 14 weeks. Twenty-five patients from the above groups (11 from the calcium-treated group and 14 from the placebo group) were studied in a crossover fashion for 14 more weeks. The high calcium intake lowered systolic blood pressure by 17 mm Hg (P < .01), and diastolic blood pressure by 11 mm Hg (P < .01). Fifty percent of the calcium-treated patients showed a significant antihypertensive effect and were termed calcium responders. In the crossover study, serum sodium was lower after taking calcium than after placebo intake (P < .05). Pretreatment plasma free calcium content of the calcium-responsive patients was significantly lower (P < .05) than in the calcium nonresponsive patients, and was highly significantly increased (P < .01) after administering calcium. The result showed that oral calcium supplementation can lower blood pressure in a significant fraction of essential hypertensive subjects, and that the free calcium level in plasma may help identify calcium-responsive individuals. While the mechanism by which increased calcium intake lowers blood pressure in hypertension is still undetermined, these data support an underlying relationship between hypertension and calcium and possibly sodium metabolism.

Expression of recombinant human casein kinase II and recombinant heat shock protein 90 in Escherichia coli and characterization of their interactions

To assess the interaction of human casein kinase II (CKII) with the heat shock protein 90 (HSP90) class of chaperone proteins, human CKII alpha and beta subunits and beta S2A mutant were expressed and purified separately or from a tandem coexpression construct in Escherichia coli. Recombinant human HSP90 beta and recombinant yeast HSP90 as His6 constructs were also expressed in and purified from E. coli. The rhCKII S2A mutant removed the regulatory beta subunit autophosphorylation site but had no effect on catalytic efficiency with peptide or protein substrates. As a CKII substrate, recombinant hHSP90 beta displayed a Km of 9.8 microM and a kcat of 4.1 min-1 and was phosphorylated to 1.5 mol/mol, whereas ryHSP90, lacking the known serine CKII sites of hHSP90, was phosphorylated at a 19-fold lower kcat/Km ratio to levels of 0.8 mol/mol. The endoplasmic reticulum HSP90 family member Grp94 was phosphorylated to 1.4 mol/mol but, in contrast, HSC70 and FKBP25 chaperones were phosphorylated to < 0.01 mol/mol. Neither phospho nor dephospho forms of hHSP90 showed significant activation of CKII toward the peptide substrate RRREEETEEE in contrast to a previous report that activation was observed at high molar ratios of chaperone to kinase.

Amino acid residues 24-31 but not palmitoylation of cysteines 30 and 45 are required for membrane anchoring of glutamic acid decarboxylase, GAD65

The smaller isoform of the GABA synthesizing enzyme glutamic acid decarboxylase, GAD65, is synthesized as a soluble protein that undergoes post-translational modification(s) in the NH2-terminal region to become anchored to the membrane of small synaptic-like microvesicles in pancreatic beta cells, and synaptic vesicles in GABA-ergic neurons. A soluble hydrophilic form, a soluble hydrophobic form, and a hydrophobic firmly membrane-anchored form have been detected in beta cells. A reversible and hydroxylamine sensitive palmitoylation has been shown to distinguish the firmly membrane-anchored form from the soluble yet hydrophobic form, suggesting that palmitoylation of cysteines in the NH2-terminal region is involved in membrane anchoring. In this study we use site-directed mutagenesis to identify the first two cysteines in the NH2-terminal region, Cys 30 and Cys 45, as the sites of palmitoylation of the GAD65 molecule. Mutation of Cys 30 and Cys 45 to Ala results in a loss of palmitoylation but does not significantly alter membrane association of GAD65 in COS-7 cells. Deletion of the first 23 amino acids at the NH2 terminus of the GAD65 30/45A mutant also does not affect the hydrophobicity and membrane anchoring of the GAD65 protein. However, deletion of an additional eight amino acids at the NH2 terminus results in a protein which is hydrophilic and cytosolic. The results suggest that amino acids 24-31 are required for hydrophobic modification and/or targeting of GAD65 to membrane compartments, whereas palmitoylation of Cys 30 and Cys 45 may rather serve to orient or fold the protein at synaptic vesicle membranes.

Role of tumor necrosis factor in neonatal sepsis

In order to assess the role of tumor necrosis factor (TNF) in neonatal sepsis, plasma TNF levels were determined by a method using L929 cells at the time of septic work-up in 67 neonates. Thirty-three patients with sepsis were found to have significantly higher TNF levels (533.33 +/- 468.74 U/ml; 1 U corresponding to 1.67 pg recombinant TNF) as compared with 34 non-sepsis patients (100.0 +/- 188.97 U/ml) and 30 healthy newborns (27.33 +/- 16.17 U/ml, P < 0.05, respectively). The upper limit of normal plasma TNF levels was 60 U/ml and the best cutoff value for predicting neonatal sepsis was 160 U/ml. This had remarkable sensitivity (88%), specificity (82%), positive predictive value (83%), and negative predictive value (88%). Plasma TNF levels were significantly associated with the occurrence of shock, organ failure, scleroma and outcome. Thus, anti-TNF antibodies might be used in protecting newborns from septic death.

Measurement of the Mueller scattering matrix by use of optical beats from a Zeeman laser

A two-frequency beam from a Zeeman laser scatters elastically from an isotropic medium, such as randomly oriented viruses or other particles suspended in water. The Zeeman effect splits the laser line by 250 kHz, and beats can be seen electronically in the signal from a phototube that views the scattered light. There are independently rotatable half-wave and quarter-wave retardation plates in the incident beam and a similar pair in the observed scattered beam, plus a fixed linear polarizer directly in front of the detector. Each of the four retarders has two angular positions, providing a total of 16 possible polarization cases. For each of the 16 cases, there are three data to be collected: (1) the average total intensity of the scattered light, (2) the amplitude of the beats in the scattered light, and (3) the phase shift between the beats of the scattered light and those of a reference signal from the laser. When a singular value decomposition technique is used, these threefold redundant data are rapidly ransformed into a best-fit 4 × 4 Mueller scattering matrix. We discuss several different measurement strategies and their systematic and statistical errors. We present experimental results for two kinds of particle of wavelength size: polystyrene spheres and tobacco mosaic virus. In both cases the achiral retardation element M(34) of the Mueller matrix is easily measurable.

Role of DNA fragmentation in T cell activation-induced apoptosis in vitro and in vivo

Apoptotic cell death, characterized by DNA fragmentation and morphologic changes, has previously been shown to occur in immature thymocytes and some T cell hybridomas after activation. Like some other forms of apoptosis, DNA fragmentation during activation-induced cell death precedes the morphologic events. For apoptosis to proceed, activation of the cells must persist at least to the time of DNA fragmentation, before which the cells can remain viable if the activation signal is removed. Aurintricarboxylic acid (ATA) blocks activation-induced apoptotic cell death in a T cell hybridoma, and kinetic studies show that this inhibition occurs at or near the time of DNA fragmentation in the cells. Taken together with the ability of ATA to inhibit DNA fragmentation in isolated nuclei exposed to Ca2+ and Mg2+, these data strongly suggest that ATA prevents apoptosis via its ability to inhibit endogenous endonuclease activity, and, conversely, that this activity is required for this form of cell death. In vivo, ATA inhibits thymocyte depletion and DNA fragmentation induced by anti-CD3 Ab. Further, specific loss of V beta 8+ thymocytes after administration of staphylococcal enterotoxin B is blocked by administration of ATA. These observations support an essential role for DNA fragmentation as an irreversible step in activation-induced apoptosis in T cell hybridomas and during T cell development. This is contrasted with heat shock-induced cell death, in which inhibition of DNA fragmentation does not prevent loss of cell viability.

Role of DNA fragmentation in T cell activation-induced apoptosis in vitro and in vivo

Apoptotic cell death, characterized by DNA fragmentation and morphologic changes, has previously been shown to occur in immature thymocytes and some T cell hybridomas after activation. Like some other forms of apoptosis, DNA fragmentation during activation-induced cell death precedes the morphologic events. For apoptosis to proceed, activation of the cells must persist at least to the time of DNA fragmentation, before which the cells can remain viable if the activation signal is removed. Aurintricarboxylic acid (ATA) blocks activation-induced apoptotic cell death in a T cell hybridoma, and kinetic studies show that this inhibition occurs at or near the time of DNA fragmentation in the cells. Taken together with the ability of ATA to inhibit DNA fragmentation in isolated nuclei exposed to Ca2+ and Mg2+, these data strongly suggest that ATA prevents apoptosis via its ability to inhibit endogenous endonuclease activity, and, conversely, that this activity is required for this form of cell death. In vivo, ATA inhibits thymocyte depletion and DNA fragmentation induced by anti-CD3 Ab. Further, specific loss of V beta 8+ thymocytes after administration of staphylococcal enterotoxin B is blocked by administration of ATA. These observations support an essential role for DNA fragmentation as an irreversible step in activation-induced apoptosis in T cell hybridomas and during T cell development. This is contrasted with heat shock-induced cell death, in which inhibition of DNA fragmentation does not prevent loss of cell viability.

YY1 is the cellular factor shown previously to bind to regulatory regions of several leaky-late (beta gamma, gamma 1) genes of herpes simplex virus type 1

We have recently reported that a cellular factor, the leaky-late binding factor (LBF), binds to sites in a number of leaky-late (beta gamma or gamma 1) genes of herpes simplex virus type 1 and that an LBF site is essential for maximum viral transactivation of the major capsid protein (VP5) gene. The results of binding competition, partial proteolysis, and monoclonal antibody inhibition assays presented here establish that LBF is identical to the transcription factor YY1. This, along with our previous observations, suggests that YY1 plays a role in herpes simplex virus type 1 gene regulation.

Cloning, sequencing, and expression in Escherichia coli of the gene encoding a 45-kilodalton protein, elongation factor Tu, from Chlamydia trachomatis serovar F

The gene encoding a 45-kDa protein (45K) of Chlamydia trachomatis serovar F was cloned, sequenced, and overexpressed in Escherichia coli. Alignment of the deduced peptide sequence with E. coli elongation factor Tu (EF-Tu) demonstrated 69% identity. The 45K was recognized by a Chlamydia genus-specific monoclonal antibody GP-45 and cross-reacted with a monospecific polyclonal antibody to E. coli EF-Tu. Purified recombinant 45K has the capability to bind GDP, and the binding was enhanced in the presence of E. coli elongation factor Ts (EF-Ts). The GDP binding was specifically inhibited by the monoclonal antibody GP-45. These data suggest that the 45K is a chlamydial EF-Tu, and it forms a functional complex with E. coli EF-Ts protein.

Fibroblast growth factors mobilize peritoneal macrophage intracellular calcium

Macrophages have been implicated in the propagation of inflammatory disease. The evidence linking macrophages to inflammation stems from their elicited responses to various extracellular ligands eventually culminating in the elaboration of a variety of inflammatory mediators. As part of an investigation of fibroblast growth factors role in promoting inflammation, we examined one aspect of transmembrane signal transduction, intracellular calcium mobilization following culture of murine peritoneal macrophages with acidic and basic fibroblast growth factor. Peritoneal macrophages displayed a rapid rise in cytosolic calcium from a basal level of 147.6 +/- 25.4 nM to 261.9 +/- 49.9 nM at 3.5 minutes following culture with acidic fibroblast growth. A similar rise in calcium was noted with basic fibroblast growth factor. Titration revealed the maximal effective dose of aFGF and bFGF with respect to calcium response to be 10 ng/ml. Using blockers of both voltage and non-voltage gated channels, the FGF induced rise in cytosolic calcium was specifically abolished. Similarly, using specific 5-lipoxygenase (A69412) or cyclooxygenase (Indomethacin) blockers, the aFGF induced rise in maximal calcium response was reduced by 41% and 96% respectively. On the basis of these data, we speculate on some possible roles that FGF may play in the inflammatory response.

Composition of peritoneal macrophage membranes in autoimmune MRL lpr/lpr mice

Adult MRL lpr/lpr mice display phenotypic features that are consistent with both rheumatoid arthritis and systemic lupus erythematosus. Previous studies have reported that peritoneal macrophages harvested from this model have an increased propensity for both spontaneous and elicited release of prostaglandins and leukotrienes relative to immunologically normal control mice. To investigate whether one aspect of the differences in secretory potential between autoimmune and normal mice was at the level of increased substrate availability, gas chromatographic analysis of peritoneal macrophage membranes from autoimmune MRL lpr/lpr, young lpr, wild type +/+, and immunologically normal mice was done. The results demonstrate enrichment of arachidonate in adult lpr macrophage membranes in all major phospholipid classes relative to young lpr, +/+ and immunologically normal C3H/HeN mice. Similarly, there was an increased mole % of arachidonic acid in lpr mice relative to controls. Elevated membrane arachidonate may contribute to the increased propensity of autoimmune strains to participate in the inflammatory process.

Low rate of ret proto-oncogene activation (PTC/retTPC) in papillary thyroid carcinomas from Saudi Arabia

BACKGROUND

The ret proto-oncogene activation (PTC/retTPC oncogene) in thyroid papillary carcinoma has been reported in different populations with different frequencies. Thyroid papillary carcinoma appears to behave more aggressively in the Persian Gulf region than elsewhere. In the current study, the frequency of PTC/retTPC oncogene in thyroid tumors from Saudi Arabia was investigated.

METHODS

PTC/retTPC oncogene transcripts were analyzed by the polymerase chain reaction amplification of cDNA synthesized by treatment of total RNA with reverse transcriptase. Seven multinodular goiters, 1 follicular adenoma, 4 follicular carcinomas, 40 papillary carcinomas, and 5 anaplastic carcinomas were studied.

RESULTS

Only one papillary carcinoma specimen was found to have PTC/retTPC oncogene transcripts. The breakpoint of the rearranged PTC/retTPC oncogene is identical to that previously described. The PTC/retTPC-positive sample was also examined for p53 tumor suppressor gene mutations in exons 5-8. One transitional point mutation was detected at codon 161 (GCC to ACC), changing Ala to Thr.

CONCLUSIONS

This study questions the relevance of PTC/retTPC oncogene in the carcinogenesis of thyroid papillary carcinomas in the Saudi population. Genetic background among races may contribute to the different frequencies of PTC/retTPC oncogene in thyroid papillary carcinoma.

Action of toosendanin on the membrane current of mouse motor nerve terminals

By perineurial recording, the actions of toosendanin on three potassium currents and two calcium currents in the nerve terminal were observed in the intercostal nerve triangularis stein muscle of the mouse. Toosendanin partially blocked the voltage-dependent fast K+ current and irreversibly increased the voltage-dependent slow Ca2+ current. The increase in the Ca2+ current of the nerve terminal accounts for the facilitation of transmitter release and the antibotulismic effect of toosendanin.

Yin-yang 1 activates the c-myc promoter

Previous studies on the murine c-myc promoter demonstrated that a ubiquitously present protein, common factor 1 (CF1), bound at two sites located -260 and -390 bp from the P1 transcription start site. CF1 has been purified to near homogeneity and shown to be identical to the zinc finger protein Yin-yang 1 (YY1) as judged by similarity of molecular weight and other biochemical properties, immunological cross-reactivity, and the ability of recombinant YY1 to bind to CF1 sites. In cotransfection experiments, YY1 is a strong activator of transcription from c-myc promoter-based reporters. Furthermore, in murine erythroleukemia cells, overexpressed YY1 causes increased levels of c-myc mRNA initiated from both major transcription initiation sites of the endogenous c-myc gene.

Field evaluation of bednets impregnated with deltamethrin for malaria control

Trials were undertaken in a hypoendemic area of malaria in an area bordering Vietnam, in Napo County of Guangxi Zhuang Autonomous Region, China. The aim was to compare the relative cost effectiveness of DDT residual spraying and of bednets impregnated with deltamethrin in the malaria control program. The trials were divided into three subgroups: (1) two farming areas and one coal mining area with a total population > 20,000, where the trial consisted of mass bednets impregnated with deltamethrin 15 mg/m2 net surface once a year, (2) one farming area with a population of approximately 3,600 where DDT residual spraying at 2g/m2 was carried out twice a year in May and August; (3) one farming area and one coal mining village with a population of > 4,000 were used as a control. The malaria vector population consisted mainly of Anopheles minimus and An. anthropophagus with a small contribution from An. sinensis. After bednets were impregnated with deltamethrin the mosquitos resting on the surface of the bednets decreased significantly, although there was less effect on the total vector population. The results showed that malaria incidence decreased significantly both in areas where impregnated bednets were used and in areas where residual spraying was undertaken. The positive IFAT rates of residents who slept under impregnated bednets decreased significantly in farming areas, especially in that area where bednet impregnation as a vector control measure had been undertaken for two years, but there was no change in the IFAT rate in DDT sprayed or control areas.(ABSTRACT TRUNCATED AT 250 WORDS)