Efficient and accurate time-stepping schemes for integrate-and-fire neuronal networks

To avoid the numerical errors associated with resetting the potential following a spike in simulations of integrate-and-fire neuronal networks, Hansel et al. and Shelley independently developed a modified time-stepping method. Their particular scheme consists of second-order Runge-Kutta time-stepping, a linear interpolant to find spike times, and a recalibration of postspike potential using the spike times. Here we show analytically that such a scheme is second order, discuss the conditions under which efficient, higher-order algorithms can be constructed to treat resets, and develop a modified fourth-order scheme. To support our analysis, we simulate a system of integrate-and-fire conductance-based point neurons with all-to-all coupling. For six-digit accuracy, our modified Runge-Kutta fourth-order scheme needs a time-step of Delta(t) = 0.5 x 10(-3) seconds, whereas to achieve comparable accuracy using a recalibrated second-order or a first-order algorithm requires time-steps of 10(-5) seconds or 10(-9) seconds, respectively. Furthermore, since the cortico-cortical conductances in standard integrate-and-fire neuronal networks do not depend on the value of the membrane potential, we can attain fourth-order accuracy with computational costs normally associated with second-order schemes.

[The relationship between postburn enterogenic hypermetabolism and decontamination of intestine]

OBJECTIVE

To explore whether postburn enterogenic hypermetabolism exists.

METHODS

Eighty -- eight Wistar rats inflicted by 30% TBSA III degree burns were randomly divided into two groups, i,e. burn (B) and burn with gut decontamination (D) groups. The change in resting energy expenditure (REE) was observed during 0 to 10 postburn day (PBDs) in rats. The plasma contents of lipopolysaccharide (LPS), tumor necrosis factor (TNF) and interleukin-1 (IL-1) were determined on 1, 3, 5, 7 and 10 PBDs and their correlations were analyzed.

RESULTS

The postburn REE and plasma contents of TNF, LPS and IL-1 were much higher in both groups than those before injury. When compared between the two groups, the above data in D group were lower in varying degrees than those in B group. It was shown by correlation analysis that REE was postively correlated to LPS, TNF and IL-1, respectively (gamma = 0.77 similar 0.9, P < 0.05 similar 0.01).

CONCLUSION

Postburn hypermetabolism in rats could be ameliorated by gut decontamination, and the postburn plasma inflammatory mediators in rats could also be lowered by gut decontmination. This suggests that enterogenic hypermetabolism does exist after burn injury.

The effect of dichloroacetic acid and trichloroacetic acid on DNA methylation and cell proliferation in B6C3F1 mice

The chlorine disinfection by-products, dichloroacetic acid (DCA) and trichloroacetic acid (TCA), are carcinogenic in mouse liver. We have previously reported that DCA and TCA induced DNA hypomethylation in mouse liver. In the present study, we determined the temporal association for DNA hypomethylation and cell proliferation. Female B6C3F1 mice were administered daily doses of 500 mg/kg DCA or TCA by gavage and sacrificed at 24, 36, 48, 72, and 96 hours after the first dose. The proliferating cell nuclear antigen-labeling index in the liver was increased at 72 and 96 hours by both DCA and TCA, that is, at 72 hours the index was 1.00 +/- 0.21, 0.51 +/- 0.11, and 0.095 +/- 0.016 for DCA, TCA, and the vehicle control, respectively. The mitotic index was also significantly increased at 96 hours. The promoter region for the c-myc gene was hypomethylated only at 72 and 96 hours and not at the earlier sacrifices. Similarly, the methylation of the c-myc gene in the kidney and urinary bladder was decreased only at 72 and 96 hours. In summary, enhancement of cell proliferation and decreased methylation of the c-myc gene were first observed simultaneously at 72 hours after the start of exposure. Thus, the results support the hypothesis that DCA and TCA induce DNA hypomethylation by inducing DNA replication and preventing the methylation of the newly synthesized strands of DNA.

Wy-14,643-induced hypomethylation of the c-myc gene in mouse liver

The carcinogenic activity of Wy-14,643 in mouse liver appears to be nongenotoxic and could involve a decrease in DNA methylation. The mechanism for Wy-14,643-induced decrease in DNA methylation is proposed to involve increased cell proliferation followed by prevention of the methylation of the newly synthesized DNA. To investigate this mechanism, female B6C3F1 mice were administered daily by oral gavage 50 mg/kg Wy-14,643. Mice were sacrificed at 2, 5, 8, 24, 26, 29, 32, 36, 48, 72, and 96 h after the first dose. Some mice also received 450 mg/kg methionine by ip injection at 30 min after administering Wy-14,643. Hypomethylation of the c-myc gene first occurred at 48 h after the first dose of Wy-14,643. Cell proliferation determined by the Proliferating Cell Nuclear Antigen (PCNA)-Labeling Index started to increase at 36 h and peaked at 72h. Wy14,643 did not affect the liver concentration of either S-adenosyl methionine (SAM) or S-adenosyl homocysteine (SAH). Methionine prevented and reversed the hypomethylation of the c-myc gene induced by Wy-14,643. However, the increased levels of SAM and SAH returned to control levels prior to the prevention by methionine of Wy-14,643-induced hypomethylation. Furthermore, methionine did not prevent Wy-14,643-induced increase in the PCNA-Labeling Index. The activity of nuclear DNA methyltransferase (DNA MTase) was increased at 72 and 96 h after administering Wy14,643. Wy14,643 also increased the activity of DNA MTase when added in vitro to nuclear extracts. The results are consistent with Wy-14,643 decreasing the methylation of the c-myc gene by a mechanism that includes enhancement of cell proliferation followed by prevention of the methylation of the newly synthesized DNA. However, the results indicate that Wy-14,643 does not prevent methylation by decreasing either the availability of SAM or the activity of DNA MTase.

Immunogenicity of the extracellular domains of C-C chemokine receptor 5 and the in vitro effects on simian immunodeficiency virus or HIV infectivity

The C-C chemokine receptor CCR5 serves an important function in chemotaxis of lymphocytes, monocytes, and dendritic cells. CCR5 is also the major coreceptor in most macrophage-tropic HIV-1 infections. Immunization of rhesus macaques with a baculovirus-generated CCR5 construct or peptides derived from the sequences of the four extracellular domains of CCR5 elicited IgG and IgA Abs, inhibition of SIV replication, and CD4+ T cell proliferative responses to three of the extracellular domains of CCR5. The immune sera reacted with cell surface CCR5 expressed on HEK 293 cells. T and B cell epitope mapping revealed major and minor T and B cell epitopes in the N-terminal, first, and second loops of CCR5. The three C-C chemokines, RANTES, macrophage-inflammatory protein-1alpha, and macrophage-inflammatory protein-1beta, were up-regulated by immunization with the CCR5-derived peptides, and the cell surface expression of CCR5 was decreased. The CCR5 Abs were complementary to the C-C chemokines in inhibiting HIV replication in vitro. Immunization with the four extracellular domains of CCR5 suggests that three of them are immunogenic, with maximal T cell responses being elicited by the second loop peptide. However, maximal Abs to the cell surface CCR5 or viral inhibitory Abs in vitro were induced by the N-terminal peptide. Up-regulation of the three C-C chemokines and down-modulation of cell surface CCR5 were elicited by the second loop, N-terminal, and first loop peptides. The data suggest that a dual mechanism of C-C chemokines and specific Abs may engage and down-modulate the CCR5 coreceptors and prevent in vitro HIV or SIV replication.

[Study on the association of transporter associated with antigen processing gene with ankylosing spondylitis and HLA-B27 in Han nationality]

OBJECTIVE

To investigate the association between transporter associated with antigen processing(TAP) gene and ankylosing spondylitis(AS) as well as HLA-B27.

METHODS

PCR-SSO was used to analyze the frequencies of TAP alleles and variant amino acids of TAP in 48 patients (B27(+)) with AS and 123 normal individuals (B27(+) or B27(-)).

RESULTS

The phenotypes of Ile/Ile, Asp/Asp were over-presented for TAP1 and Val/Val, Ala/Thr, Stop/Stop for TAP2 in Han nationality. For each TAP there were four alleles: TAP1*0101, TAP1*0201, TAP1*0301, TAP1*0401, and TAP2*0101, TAP2*0102, TAP2*0201, TAP2*0202. In the research subjects, hybridization blanks accounted for 9.9%(17/171) of TAP1 and 15.8%(27/171) of TAP2. No difference was found in the distribution of TAP alleles between the AS patients(B27(+)) and normal controls(B27(+) or B27(-)). In the patients group the frequency of phenotype in codon of 333 (Val/Val) was significantly decreased as compared with that of the healthy controls(B27(+))(P<0.05). In addition, the frequency of phenotype Ala/Ala(665) was significantly decreased and that of Ala/Thr was significantly increased in normal controls(B27(-)), compared with those in normal controls(B27(+))(P<0.05).

CONCLUSION

It is possible that there are new TAP alleles in Han nationality. No association was found between TAP alleles and AS. And the homozygosity for codon 333 which is Val/Val seems to offer resistance to AS among those HLA-B27(+) individuals. In normal individuals, negative correlation was found between heterozygote Ala/Thr and B27, and possibly there was positive correlation between phenotype Ala/Ala and B27.

Hepatic uptake and metabolism of benzoate: a multiple indicator dilution, perfused rat liver study

Multiple, noneliminated references ((51)Cr-labeled erythrocytes, (125)I-albumin, [(14)C]- or [(3)H]sucrose, and [(2)H](2)O), together with [(3)H]hippurate or [(14)C]benzoate, were injected simultaneously into the portal vein of the perfused rat liver during single-pass delivery of benzoate (5-1,000 microM) and hippurate (5 microM) to investigate hippurate formation kinetics and transport. The outflow dilution data best fit a space-distributed model comprising vascular and cellular pools for benzoate and hippurate; there was further need to segregate the cellular pool of benzoate into shallow (cytosolic) and deep (mitochondrial) pools. Fitted values of the membrane permeability-surface area products for sinusoidal entry of unbound benzoate were fast and concentration independent (0.89 +/- 0.17 ml. s(-1). g(-1)) and greatly exceeded the plasma flow rate (0.0169 +/- 0.0018 ml. s(-1). g(-1)), whereas both the influx of benzoate into the deep pool and the formation of hippurate occurring therein appeared to be saturable. Results of the fit to the dilution data suggest rapid uptake of benzoate, with glycination occurring within the deep and not the shallow pool as the rate-determining step.

[Ecological analysis and optimization design for agricultural landscape of coastal zone along Radial Submarine Sand Ridges in north Jiangsu]

The Radial Submarine Sand Ridges (RSSR) on the inner shelf of the Southwestern Yellow Sea is one of the largest of such system in the world. It was developed into great amount of land which is mainly used for agriculture. However, the coastal zone is facing many serious environmental and resources problems such as coastal erosion, ecological fragility and over- and abuse of coastal resources. Based on comprehensive field survey, this paper proposes optimization allocation and design of agri-landscape spatial structures targeting an integrated improvement in agricultural ecology, economy and amenity of the region as well as implementation of sustainable development strategy. As a case study, rectification approaches and conceptual optimization design for Rudong County are proposed and discussed.

Construction of adenoviral vectors

Recombinant adenovirus vectors have proven to be useful tools in facilitating gene transfer. Construction of such vectors requires a knowledge of the adenovirus genome structure and its life cycle. A commonly used recombinant adenovirus involves deletion of the E1 region; such a recombinant is traditionally produced by overlap recombination after cotransfection of 293 cells with a plasmid shuttle vector and a large right-end restriction fragment of viral DNA. The shuttle vector contains a cassette for a transgene placed in region E1 and flanking sequences from adenovirus for recombination. Normally, a high background of parental virus results because of the difficulty in separating right-end restriction fragment length DNA from uncut DNA. This paper describes a negative selection based on the traditional cotransfection method using viral DNA from an E1-deleted adenoviral recombinant that expresses green fluorescent protein (GFP). In situ fluorescent microscopy is used to distinguish the recombinant plaques (white or nonfluorescent) from the parental virus plaques (green or fluorescent). In addition, this system allows for the detection of contaminating parental virus at later stages when production lots of the recombinant vector are being made.

Goblet cell carcinoid of the appendix: Investigation of the expression of beta-catenin and E-cadherin

Goblet cell carcinoids are rare neoplasms that predominantly occur in the appendix. In this report we present a case of goblet cell carcinoid of the appendix. A 58-year-old male patient complaining of pain in the right lower quadrant was diagnosed with acute appendicitis and underwent an appendectomy. Histological examination of the resected appendix revealed goblet cell carcinoid. Infiltration of tumor cells beyond the appendix was observed and the surgically resected margin was positive for tumor cells. Carcinoembryonic antigen (CEA) was diffusely detected by immunohistochemistry, and cytokeratin 20, neuron-specific enolase (NSE), chromogranin A and serotonin were focally observed in the tumor cells. The expression of beta-catenin and E-cadherin was investigated to compare with that of typical rectal carcinoids (n = 3) and colon adenocarcinomas (n = 3). In normal colonic and rectal mucosae, beta-catenin and E-cadherin stained positive on the plasma membrane. In the case reported here, beta-catenin showed a preserved expression on the plasma membrane of goblet cell carcinoid; a pattern similar to typical carcinoids rather than to adenocarcinomas. However, E-cadherin demonstrated a reduced expression on the plasma membrane of the tumor cells. This staining pattern was identical to those both of carcinoids and of adenocarcinomas. These findings suggest the possibility that, in some cases, the adherens junctions of goblet cell carcinoids are similar to those of typical carcinoids rather than to those of adenocarcinomas.

Adult-onset herpes simplex virus hepatitis with diffuse myofibroblastic transformation of hepatic stellate cells (Ito cells) in non-necrotic areas

The myofibroblastic transformation of hepatic stellate cells (HSC; also known as Ito cells) usually occurs following necrosis of adjacent liver cells. No report has previously found that such a transformation occurs in herpes simplex virus (HSV) hepatitis. We present an autopsy case of HSV hepatitis with myofibroblastic transformation of HSC that is different from the usual transformation of HSC. The patient was a 66-year-old woman who had received various therapies for cutaneous T-cell lymphoma. An autopsy revealed submassive hepatic necrosis with hemorrhage due to HSV hepatitis. HSV infection was confirmed by DNA in situ hybridization in liver tissue. Immunohistochemical staining for alpha-smooth muscle actin (ASMA) showed a strong positive reaction in almost all of the HSC in non-necrotic areas. However, in necrotic areas, the HSC were completely negative for ASMA. These findings indicate that not only liver cells but also HSC can become necrotic in HSV hepatitis. In contrast, in non-necrotic areas, almost all of the HSC showed active transformation to myofibroblasts.

Dopamine-mediated volume transmission in midbrain is regulated by distinct extracellular geometry and uptake

Somatodendritic release of dopamine (DA) in midbrain is, at least in part, nonsynaptic; moreover, midbrain DA receptors are predominantly extrasynaptic. Thus somatodendritic DA mediates volume transmission, with an efficacy regulated by the diffusion and uptake characteristics of the local extracellular microenvironment. Here, we quantitatively evaluated diffusion and uptake in substantia nigra pars compacta (SNc) and reticulata (SNr), ventral tegmental area (VTA), and cerebral cortex in guinea pig brain slices. The geometric parameters that govern diffusion, extracellular volume fraction (alpha) and tortuosity (lambda), together with linear uptake (k'), were determined for tetramethylammonium (TMA(+)), and for DA, using point-source diffusion combined with ion-selective and carbon-fiber microelectrodes. TMA(+)-diffusion measurements revealed a large alpha of 30% in SNc, SNr, and VTA, which was significantly higher than the 22% in cortex. Values for lambda and k' for TMA(+) were similar among regions. Point-source DA-diffusion curves fitted theory well with linear uptake, with significantly higher values of k' for DA in SNc and VTA (0.08--0.09 s(-1)) than in SNr (0.006 s(-1)), where DA processes are sparser. Inhibition of DA uptake by GBR-12909 caused a greater decrease in k' in SNc than in VTA. In addition, DA uptake was slightly decreased by the norepinephrine transport inhibitor, desipramine in both regions, although this was statistically significant only in VTA. We used these data to model the radius of influence of DA in midbrain. Simulated release from a 20-vesicle point source produced DA concentrations sufficient for receptor activation up to 20 microm away with a DA half-life at this distance of several hundred milliseconds. Most importantly, this model showed that diffusion rather than uptake was the most important determinant of DA time course in midbrain, which contrasts strikingly with the striatum where uptake dominates. The issues considered here, while specific for DA in midbrain, illustrate fundamental biophysical properties relevant for all extracellular communication.

Interleukin-2 modulates N-methyl-D-aspartate receptors of native mesolimbic neurons

Interleukin (IL)-2 is a brain-derived cytokine that influences mesocorticolimbic dopamine release, and is associated with pathological outcomes that are mediated, at least in part, by aberrations in mesolimbic neurotransmission. The mechanisms by which IL-2 modulates mesolimbic transmission, however, are not known. The NMDA receptor/channel (NMDAR) plays an essential role in neuronal excitability of mesolimbic neurons; we thus examined in neonatal rats the effects of IL-2 on NMDA-activated current (I(NMDA)) in voltage-clamped neurons freshly isolated from the ventral tegmental area (VTA), the site of origin of the mesolimbic system. IL-2 (0.01-500 ng/ml) alone had no effect on membrane conductance. When co-applied with NMDA, IL-2 (50-500 ng/ml) significantly potentiated I(NMDA). In contrast, doses as low as 0.01 ng/ml markedly decreased the NMDA response. Dose-response analysis showed that IL-2 ( > 50 ng/ml) increased the maximal I(NMDA), without changing the EC(50), indicating that IL-2 potentiates I(NMDA) by increasing the efficacy of the NMDAR. Moreover, current-voltage analysis revealed that IL-2 potentiation of I(NMDA) was voltage-dependent, being greater at negative potentials. In contrast, IL-2 inhibition of I(NMDA) was voltage-independent, and IL-2 did not alter the reversal potential. Additionally, IL-2 (1 ng/ml) shifted the NMDA concentration-response curve to the right, significantly increasing the EC(50) for NMDA without changing the maximal I(NMDA), suggesting that IL-2 inhibits the NMDAR by a competitive mechanism. IL-2 thus acts as a potent modulator of the NMDAR. IL-2-induced alterations of responses to NMDAR activation may contribute to synaptic plasticity in the mesolimbic system and to pathological outcomes associated with this system.

Diffusion of molecules in brain extracellular space: theory and experiment

Volume transmission depends on the migration of informational substances through brain extracellular space (ECS) and almost always involves diffusion; basic concepts of diffusion are outlined from both the microscopic viewpoint based on random walks and the macroscopic viewpoint based on the solution of equations embodying Fick's Laws. In a complex medium like the brain, diffusing molecules are constrained by the local volume fraction of the ECS and tortuosity, a measure of the hindrance imposed by cellular obstacles. Molecules can also experience varying degrees of uptake or clearance. Bulk flow and the extracellular matrix may also play a role. Examples of recent work on diffusion of tetramethylammonium (molecular weight, 74) in brain slices, using iontophoretic application and ion-selective microelectrodes, are reviewed. In slices, the volume fraction is about 20% and tortuosity about 1.6, both similar to values found in the intact brain. Using integrative optical imaging, results obtained with dextrans and albumins up to a molecular weight of 70,000 are summarized, for such large molecules the tortuosity is about 2.3. Experiments using synthetic long-chain PHPMA polymers up to 1,000,000 molecular weight show that these molecules also diffuse in the ECS but with a tortuosity of about 1.6. Studies with osmotic challenge show that volume fraction and tortuosity do not vary together as expected when the size of the ECS changes; a model is presented that explains the osmotic-challenge on the basis of changes in cell shape. Finally, new analytical insights are provided into the complex movement of potassium in the brain.

Detection and nucleotide analysis of RNA5 of beet necrotic yellow vein virus isolated in China

Using the RT-PCR method, five isolates of beet necrotic yellow vein virus from China were used for the RNA5 genomic component detection and sequence analysis. The result showed that RNA5 was only found in the isolates from Baotou and Hohhot, but not in those of Xingjiang, Helongjiang, and Wulate of Inner Mongolia. The RNA5 components had 1338 nucleotides and 1358 nucleotides in the length of Baotou and Hohhot isolates, respectively, in which the single open reading frame (ORF) encoding for a proteins of 26kD were contained. Compared with the published sequences of F72 and D5 isolates, these RNA5 components shared the identity of 93.7% approximately 98.5% in nucleotide acids and 91.8%-98.2% in deduced amino acids.

Comparative study of vaginal Lactobacillus phages isolated from women in the United States and Turkey: prevalence, morphology, host range, and DNA homology

Lactobacilli play an important role in maintaining vaginal health. However, during bacterial vaginosis lactobacilli decrease for unknown reasons. Our preliminary study showed that phages could infect vaginal lactobacilli. Therefore, the aim of this study was to analyze the distribution, virulence, and types of vaginal Lactobacillus phages isolated from women of two countries: the United States and Turkey. A total of 209 vaginal lactobacilli were isolated from reproductive-aged women in the United States (n = 107) and Turkey (n = 102). By analysis of 16S rRNA gene sequence and by comparison of protein profiles, most lactobacilli were identified as L. crispatus, L. gasseri, and L. jensenii. After mitomycin C induction, 28% of American lactobacilli and 36% of Turkish lactobacilli released phages. A total of 67 phages were isolated and further characterized by their host range, electron microscopy, and DNA homology. All 67 phages were infective against lactobacilli from both collections. The host ranges of most phages were broad, including multiple Lactobacillus species. Even though the phages were all temperate, they were able to cause lytic infection in various strains. The electron micrographs of these phages showed a hexagon-shaped head and a long tail with or without a contractile tail sheath. Based on their morphology, these phages belonged to Bradley's phage groups A and B, and could be further classified into four morphotypes. All four types were found among American phages, but only three were found among Turkish isolates. DNA hybridization with labeled probes of the four types of phages revealed that additional genetic types existed within each morphotype among these phages. The phage genomic sizes ranged between 34 and 55 kb. Many of the lysogenic Lactobacillus strains released phages spontaneously at a high frequency of 10(-3) to 10(-4) PFU/cell. In conclusion, lysogeny in vaginal lactobacilli is widely spread. Some lysogenic lactobacilli spontaneously release phages with a broad host range, which can be lytic against other vaginal lactobacilli regardless of their geographic origin.

Poly[N-(2-hydroxypropyl)methacrylamide] polymers diffuse in brain extracellular space with same tortuosity as small molecules

Integrative optical imaging was used to show that long-chain synthetic poly[N-(2-hydroxypropyl)methacrylamide] (PHPMA) polymers in a range of molecular weights from 7.8 to 1057 kDa were able to diffuse through the extracellular space in rat neocortical slices. Tortuosity (square root of ratio of diffusion coefficient in aqueous medium to that in brain) measured with such polymers averaged 1.57, a value similar to that obtained previously with tetramethylammonium, a small cation. When PHPMA was conjugated with bovine serum albumin (BSA) to make a bulky polymer with molecular weight 176 kDa, the tortuosity rose to 2.27, a value similar to that obtained previously with BSA alone and with 70-kDa dextran. The method of image analysis was justified with diffusion models involving spherical and nonspherical initial distributions of the molecules.

Ethanol potentiation of glycine-induced responses in dissociated neurons of rat ventral tegmental area

The potentiation of glycine-induced responses by ethanol (EtOH) was studied in neurons freshly dissociated from the ventral tegmental area (VTA) of 5- to 14-day-old postnatal rats using whole-cell and gramicidin-perforated patch-clamp techniques. Under current-clamp conditions, EtOH increased glycine-induced membrane depolarization and action potential firing. Under voltage-clamp conditions, EtOH (0. 1-40 mM) alone did not elicit a current. When coapplied with glycine, EtOH enhanced the glycine-induced current in 35% (180 of 474) of the neurons. The EtOH-induced enhancement of glycine current was independent of membrane potential (between -60 and +60 mV); the reversal potential was not changed. Concentration-response analysis showed that in the presence of EtOH (10 mM), the EC(50) for glycine decreased from 25 +/- 4 to 14 +/- 3 microM; the Hill coefficient increased from 1.5 +/- 0.2 to 1.9 +/- 0.3. Kinetic analysis of glycine currents indicated that EtOH decreased the time constant of activation and increased the time constant of deactivation of glycine-gated chloride channels. EtOH may accelerate glycine association with its receptor at the agonist binding site and increase the apparent agonist affinity. Our observations suggest that, at pharmacologically relevant concentrations, EtOH alters the function of glycine receptors and thus the excitability of neonatal VTA neurons. This action of EtOH may contribute to the neurobehavioral disturbances associated with fetal alcohol syndrome.

Extended X-ray absorption fine-structure study of the bound form of lanthane in chlorophyll-a from Dicranopteris dichotoma

The in vivo coordination structure of lanthanum ions interacting with chlorophyll-a of the fern Dicranopteris dichotoma grown in a rare earth minefield in southern China was determined by the extended x-ray absorption fine structure (EXAFS). The results show that lanthanum includes two porphyrin rings in its coordination sphere. It is postulated that the La-chlorophyll-a complex may have a bilayer structure. The analytical method may serve as a new tool to gain insight in the in vivo interactions of rare earth elements.

BTK mutations in patients with X-linked agammaglobulinemia: lack of correlation between presence of peripheral B lymphocytes and specific mutations

X-linked agammaglobulinemia (XLA) is a human antibody deficiency that results from mutation of the tyrosine kinase btk. We tested the hypothesis that XLA patients who varied from the classic phenotype of XLA by presence of normal or near normal number of peripheral B lymphocytes would have a set of mutations of BTK that is different from the mutations found in patients without peripheral B lymphocytes. The mutations of BTK we found in two patients with normal numbers of peripheral B lymphocytes have been previously identified in patients without peripheral B lymphocytes. A third patient, without peripheral B cells, was found to express normal levels of wild type btk. Exmination of the mutations of the BTK gene in patients in the BTKbase who were identified as having peripheral B lymphocytes found that these same mutations, or mutations of the same protein domains, were also present in patients identified as lacking peripheral B lymphocytes. Analysis of mutations in BTK has previously led to the conclusion that severity of disease in XLA cannot be predicted from the specific mutation of BTK. The results of this study suggest that whether an XLA patient will develop peripheral B lymphocytes cannot be predicted from the specific mutation of BTK.

Oxidative degradation of bilirubin produces vasoactive compounds

Subarachnoid haemorrhage is often followed by haemolysis and concomitant oxidative stress, and is frequently complicated by pathological vasoconstriction or cerebral vasospasm. It is known that upregulation of haem oxygenase (HO-1) is induced by oxidative stress and results in release of biliverdin and bilirubin (BR), which are scavengers of reactive oxygen species (ROS). Here we report biomimetic studies aimed at modelling pathological conditions leading to oxidative degradation of BR. Oxidative degradation products of BR, formed by reaction with hydrogen peroxide (an ROS model system), demonstrated biological activity by stimulating oxygen consumption and force development in vascular smooth muscle from porcine carotid artery. Analogous biological activity was observed with vasoactive cerebrospinal fluid from subarachnoid haemorrhage patients. Three degradation products of BR were isolated: two were assigned as isomeric monopyrrole (C9H11N2O2) derivatives, 4-methyl-5-oxo-3-vinyl-(1, 5-dihydropyrrol-2-ylidene)acetamide and 3-methyl-5-oxo-4-vinyl-(1, 5-dihydropyrrol-2-ylidene)acetamide and the third was 4-methyl-3-vinylmaleimide (MVM), a previously isolated photodegradation product of biliverdin. Possible mechanisms of oxidative degradation of BR are discussed. Tentative assignment of these structures in the cerebrospinal fluid (CSF) of cerebral vasospasm patients has been made. It is proposed that one or more of the degradation products of biliverdin or bilirubin are involved in complications such as vasospasm and or pathological vasoconstriction associated with haemorrhage.

Effect of trihalomethanes on cell proliferation and DNA methylation in female B6C3F1 mouse liver

Trihalomethanes (chloroform, bromodichloromethane, chlorodibromomethane, and bromoform) are regulated organic contaminants in chlorinated drinking water. In female B6C3F1 mouse liver, the 4 trihalomethanes have demonstrated carcinogenic activity when administered by oral gavage; however, chloroform was not carcinogenic when administered in drinking water. Female B6C3F1 mice were administered the trihalomethanes for 11 days by gavage at 2 dose levels or in the drinking water at approximately 75% saturation. When administered by gavage, the trihalomethanes were toxic to the liver, increased the liver:body weight (bw) ratio, and increased the proliferating cell nuclear antigen-labeling index (PCNA-LI). Chloroform and bromodichloromethane were the most toxic, and they increased the liver:bw ratio the most, while bromoform and chloroform increased the PCNA-LI the most. When administered in drinking water, the toxicity of the trihalomethanes was similar to their low gavage-dose. Furthermore, only chloroform significantly increased the liver:bw ratio and bromoform and chloroform increased the PCNA-LI. Chloroform and bromodichloromethane decreased the level of 5-methylcytosine in hepatic DNA. Methylation in the promoter region of the c-myc gene was reduced by the trihalomethanes. Chloroform administered by gavage was more efficacious than given in drinking water; the efficacy of the other trihalomethanes did not differ for the 2 routes. Thus, in mouse liver, the trihalomethanes administered by gavage enhanced cell proliferation and decreased the methylation of the c-myc gene, consistent with their carcinogenic activity. Furthermore, the more modest toxicity, enhancement of cell proliferation, and decreased methylation induced by chloroform administered in drinking water correlated with its lack of carcinogenic activity. Hence, the activity of the trihalomethanes was dependent on the rate of delivery, i.e. rapid by oral gavage and more slowly in drinking water.

Hypomethylation and overexpression of c-jun and c-myc protooncogenes and increased DNA methyltransferase activity in dichloroacetic and trichloroacetic acid-promoted mouse liver tumors

Dichloroacetic acid (DCA) and trichloroacetic acid (TCA) are mouse liver carcinogens. Methylation of the c-jun and c-myc genes, expression of both genes and DNA methyltransferase (DNA MTase) activity were determined in liver tumors initiated by N-methyl-N-nitrosourea and promoted by DCA and TCA in female B6C3F1 mice. Hypomethylated and over-expression of c-jun and c-myc genes were found in DCA- and TCA-promoted liver tumors. DNA MTase activity was increased in tumors while decreased in non-involved liver. Thus, DCA- and TCA-promoted carcinogenesis appears to include decreased methylation and increased expression of c-jun and c-myc genes in the presence of increased DNA MTase activity.

Control of the mode of excitation-contraction coupling by Ca(2+) stores in bovine trachealis muscle

Full muscarinic stimulation in bovine tracheal smooth muscle caused a sustained contraction and increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) that was largely resistant to inhibition by nifedipine. Depletion of internal Ca(2+) stores with cyclopiazonic acid resulted in an increased efficacy of nifedipine to inhibit this contraction and the associated increase in [Ca(2+)](i). Thus internal Ca(2+) store depletion promoted electromechanical coupling between full muscarinic stimulation and muscle contraction to the detriment of pharmacomechanical coupling. A similar change in coupling mode was induced by ryanodine even when it did not significantly modify the initial transient increase in [Ca(2+)](i) induced by this stimulation, indicating that depletion of internal stores was not necessary to induce the change in excitation-contraction coupling mode. Blockade of the Ca(2+)-activated K(+) channel by tetraethylammonium, charybdotoxin, and iberiotoxin all induced the change in excitation-contraction coupling mode. These results suggest that in this preparation, Ca(2+) released from the ryanodine-sensitive Ca(2+) store, by activating Ca(2+)-activated K(+) channels, plays a central role in determining the expression of the pharmacomechanical coupling mode between muscarinic excitation and the Ca(2+) influx necessary for the maintenance of tone.

Effect of efferent duct ligation on the function of the blood-testis barrier in rats

The function of the blood-testis barrier has been assessed from the ratio of the Cr-EDTA space in the parenchyma to the measured interstitial volume in the testes of rats at various times after unilateral ligation of the efferent ducts. The barrier remained effective during the phase of fluid accumulation and testicular mass gain, which was linear for at least 24 h, but the testis mass began to decrease between 32 and 40 h after efferent duct ligation, and the Cr-EDTA space at 40 and 48 h after efferent duct ligation exceeded the volume of the interstitial tissue. This finding indicated that, at these times, the barrier to Cr-EDTA, which is normally excluded from the tubules, had broken down and the marker was entering the tubules. Thereafter, the Cr-EDTA space decreased again to be less than the interstitial tissue volume, indicating a restoration of the barrier function, although degeneration of the seminiferous epithelium continued to become more obvious. The present study is the first report of a reversible breakdown of the barrier, but the relevance of the breakdown to the effects on spermatogenesis requires further study.

Effect of efferent duct ligation on the function of the blood-testis barrier in rats

The function of the blood-testis barrier has been assessed from the ratio of the Cr-EDTA space in the parenchyma to the measured interstitial volume in the testes of rats at various times after unilateral ligation of the efferent ducts. The barrier remained effective during the phase of fluid accumulation and testicular mass gain, which was linear for at least 24 h, but the testis mass began to decrease between 32 and 40 h after efferent duct ligation, and the Cr-EDTA space at 40 and 48 h after efferent duct ligation exceeded the volume of the interstitial tissue. This finding indicated that, at these times, the barrier to Cr-EDTA, which is normally excluded from the tubules, had broken down and the marker was entering the tubules. Thereafter, the Cr-EDTA space decreased again to be less than the interstitial tissue volume, indicating a restoration of the barrier function, although degeneration of the seminiferous epithelium continued to become more obvious. The present study is the first report of a reversible breakdown of the barrier, but the relevance of the breakdown to the effects on spermatogenesis requires further study.

Light scattering in brain slices measured with a photon counting fiber optic system

Measurements of intrinsic optical signals (IOSs) from neural tissue, commonly with a reflection-type or transmittance-type set-up, have been used increasingly to study physiological events. Even for the same event, however, such as spreading depression (SD) or osmotic challenge, signals of opposite polarities (increase or decrease) have been obtained by different investigators using similar set-ups under similar conditions. The origin of the inconsistencies is still unknown. It is suggested here that the inconsistencies may be caused by artifacts associated with tissue surface scattering. The main goal of this paper was to present a photon counting fiber optic (PCFO) system designed to exclude surface artifacts and predominantly measure the light scattering (LS) within the tissue. Experiments on rat neocortical slices under osmotic challenges demonstrated the consistency of the PCFO data: hypertonic challenge always increased LS signal while hypotonic challenge decreased it, as long as the challenge did not induce SD. Under strong osmotic challenge (-100 mOsm), the signal suddenly reversed the polarity at the onset of SD induced by the challenge and continued to increase until the challenge was removed. When SD was blocked by high [Mg(2+)](o), the LS signal remained decreased during the -100 mOsm challenge. A spectroscopic study with the PCFO system showed that the spectrum of tissue scattering was almost a flat function in most of the visible range (650-470 nm) with a maximum at 500 nm and a rapid drop at 450 nm.

Effect of trichloroethylene on DNA methylation and expression of early-intermediate protooncogenes in the liver of B6C3F1 mice

Trichloroethylene (TCE) is a multimedia environmental pollution that is carcinogenic in mouse liver. The ability of TCE to modulate DNA methylation and the expression of immediate-early protooncogenes was evaluated. Female B6C3F1 mice were administered 1000 mg/kg TCE by gavage 5 days/week and killed after 5, 12, or 33 days of exposure. Methylation of DNA as 5-methylcytosine was decreased by 5 days of treatment with TCE and remained reduced for 33 days. TCE also decreased the methylation of the promoter regions for the protooncogenes, c-jun and c-myc. The expression of the mRNA for the two protooncogenes was increased between 60 and 120 minutes after administering the last dose of TCE and returned to control level by 24 hours. The expression of the mRNA for c-fos remained undetectable after administering TCE. Hence, TCE decreased the methylation both of total DNA and the promoters for the c-jun and c-myc genes and increased the expression of their mRNA. The decreased methylation and increased expression of the two immediate-early protooncogenes might be associated with TCE-induced increase in cell proliferation and promotion of tumors.

[The changes of GFAP and PCNA after human brain contusion: an immunohistochemical study in forensic pathology]

In order to find out changes of GFAP and PCNA after human brain trauma, samples of 38 cases were studied by the immunnohistochemistry method combined with quantitative image analysis. The gray degree and area of PCNA positive cells increased to the maximum at the 4th day and then decreased gradually. GFAP positive cells began to increase significantly 12 hours after contusion, reached the maximum at the 4th day and stayed in high level until the 7th day. These results suggest that: (1) GFAP, PCNA show regular changes with survival time after brain contusion; (2) GFAP and PCNA can be used as time markers of brain contusion from 2-20 days.

[Effects of different nutritional support routes on the intestinal mucosa mucosainjury and renovation in burned rats]

OBJECTIVE

To compare the effects of different nutritional support routes on the intestinal mucosa in burned rats.

METHODS

Wistar rats inflicted with 30% TBSA full thickness burns were employed as the model and randomly divided into three groups: burn with enteral nutrition (EN), burn with parenteral nutrition (PN), and normal control (C). Solutions for intravenous and oral application with same volume, calorie, nitrogen and other nutrients were administered to rats in PN and EN groups, respectively. The plasma diamine oxidase (DAO) activity, the intestinal mucosa change of proliferating cell nuclear antigen (PCNA), of transmembrane electric potential difference (PD), of intestinal trefoil factor and their correlation analysis (ITF) were observed.

RESULTS

Plasma DAO activity increased obviously and PD, PCNA values, ITF content were much lower in EN, PN groups than those in C group. The ITF content, the values of PD and PCNA in EN were much higher than those in PN group, while DAO activity in EN group was obviously lower than that in PN group. In addition, ITF content was significantly negatively correlated to plasma DAO activity, and obviously positively correlated to PCNA and PD values. It is suggested that intestinal mucosa injury was much more severe in PN group than that in EN group.

CONCLUSION

Postburn intestine mucosa mucosal structural injury was related to the evident decrease of synthesis and secretion of ITF. Enteral nutrition might slow down the decrement of ITF, which could explain why EN was superior to PN in terms of decreasing intestinal mucosal injury and enhancing intestinal renovation.

Major DNA replication initiation sites in the c-myc locus in human cells

DNA replication initiation sites and initiation frequencies over 12. 5 kb of the human c-myc locus, including 4.6 kb of new 5' sequence, were determined based on short nascent DNA abundance measured by competitive polymerase chain reaction using 21 primer sets. In previous measurements, no comparative quantitation of nascent strand abundance was performed, and distinction of major from minor initiation sites was not feasible. Two major initiation sites were identified in this study. One predominant site has been located at approximately 0.5 kb upstream of exon 1 of the c-myc gene, and a second new major site is located in exon 2. The site in exon 2 has not been previously identified. In addition, there are other sites that may act as less frequently used initiation sites, some of which may correspond to sites in previous reports. Furthermore, a comparison of the abundance of DNA replication intermediates over this same region of the c-myc locus between HeLa and normal skin fibroblast (NSF) cells indicated that the relative distribution was very similar, but that nascent strand abundance in HeLa cells was approximately twice that in NSF relative to the abundance at the lamin B2 origin. This increased activity at initiation sites in the c-myc locus may mainly be influenced by regulators at higher levels in transformed cells like HeLa.

Identification of tumor-suppressor genes using human melanoma cell lines UACC903, UACC903(+6), and SRS3 by comparison of expression profiles

The development and progression of cancer are believed to be due to multiple genetic alterations resulting in complex changes in expression of many genes. The parental malignant melanoma cell line UACC903 displays anchorage-independent growth, and the chromosome 6-suppressed subline UACC903(+6) displays anchorage-dependent growth. The anchorage-independent revertant cell line SRS3 derived from UACC903(+6) by retroviral transduction resembles the phenotype of UACC903. In this study, we first compared the expression profiles of 3317 genes between these three cell lines in pairs by cDNA microarrays, resulting in identification of genes with known suppressor activities. We then demonstrated connexin 43 (Cx43)-suppressing anchorage-independent growth of UACC903 on overexpression. Of 3317 genes with informative expression detected by cDNA microarray, 321 (9.68%) showed expression changes between at least one pair of the three cell lines. Notably, 12 genes displayed higher levels of expression in UACC903(+6) than in both UACC903 and SRS3, providing candidates for further identification of melanoma-suppressor genes. Genes encoding Cx43 (suppressor activity), monocyte chemotactic protein 1 (suppressor activity), and cysteine proteinase P32alpha (apoptotic activity) were all upregulated in UACC903(+6), in contrast to both UACC903 and SRS3. Transfection of Cx43, encoded on human chromosome 6q21-q23, a region frequently altered in malignant melanoma, resulted in its overexpression and the suppression of anchorage-independent growth of UACC903. Thus, our result proves the principle that the combination of the ability to alter cellular phenotype by successive genetic alterations and the ability to examine the global expression profiles facilitates the identification of tumor suppressor genes. Mol. Carcinog. 28:119-127, 2000.

Up-regulation of beta-chemokines and down-modulation of CCR5 co-receptors inhibit simian immunodeficiency virus transmission in non-human primates

A non-cognate mechanism of protection against human immunodeficiency virus-1 (HIV-1) infection involves up-regulation of beta-chemokines, which bind and may down-modulate the CCR5 co-receptors, thereby preventing transmission of M-tropic HIV-1. The objective of this investigation was to evaluate this mechanism in vivo in non-human primates. Rhesus macaques were immunized by a modified targeted lymph nodes (TLN) route with recombinant simian immunodeficiency virus (SIV) glycoprotein 120 (gp120) and p27 in alum, and adsorbed recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) with either interleukin (IL)-2 or IL-4. Immunization induced significant increases in the concentrations of CD8 cell-derived suppressor factor (CD8-SF), regulated on activation normal T cells expressed and secreted (RANTES), macrophage inflammatory protein (MIP)-1alpha and MIP-1beta, and down-modulation of the proportion of cells expressing CCR5 (r = 0.737, P<0.05). The macaques were then challenged with SIVmac 220 by the rectal mucosal route. The plasma SIVmac RNA showed a significant inverse correlation with the CD8-SF or the concentration of the three beta-chemokines (r = 0.831 and 0.824, P<0.01), but a positive correlation between the proportion of CCR5+ cells and SIVmac RNA (r = 0.613, P = 0.05). These results demonstrate for the first time in vivo that immunization up-regulates beta-chemokines, which may down-modulate CCR5 co-receptors, and both functions are significantly correlated with the viral load. Hence, the non-cognate beta-chemokine-CCR5 mechanism should be considered as complementary to specific immunity in vaccination against HIV.

Effect of trichloroethylene and its metabolites, dichloroacetic acid and trichloroacetic acid, on the methylation and expression of c-Jun and c-Myc protooncogenes in mouse liver: prevention by methionine

Trichloroethylene (TCE), dichloroacetic acid (DCA), and trichloroacetic acid (TCA) are environmental contaminants that are carcinogenic in mouse liver. 5-Methylcytosine (5-MeC) in DNA is a mechanism that controls the transcription of mRNA, including the protooncogenes, c-jun and c-myc. We have previously reported that TCE decreased methylation of the c-jun and c-myc genes and increased the level of their mRNAs. Decreased methylation of the protooncogenes could be a result of a deficiency in S-adenosylmethionine (SAM), so that methionine, by increasing the level of SAM, would prevent hypomethylation of the genes. For 5 days, female B6C3F1 mice were administered, daily by oral gavage, either 1000 mg/kg body weight of TCE or 500 mg/kg DCA or TCA. At 30 min after each dose of carcinogen, the mice received, by ip injection, 0-, 30-, 100-, 300-, or 450-mg/kg methionine. Mice were euthanized at 100 min after the last dose of DCA, TCA, or TCE. Decreased methylation in the promoter regions of the c-jun and c-myc genes and increased levels of their mRNA and proteins were found in livers of mice exposed to TCE, DCA, and TCA. Methionine prevented both the decreased methylation and the increased levels of the mRNA and proteins of the two pro-tooncogenes. The prevention by methionine of DCA- TCA-, and TCE-induced DNA hypomethylation supports the hypothesis that these carcinogens act by depleting the availability of SAM. Hence, methionine would prevent DNA hypomethylation by maintaining the level of SAM. Furthermore, the results suggest that the dose of DCA, TCA, or TCE must be sufficient to decrease the level of SAM in order for these carcinogens to be active.

Induction of vaginal Lactobacillus phages by the cigarette smoke chemical benzo[a]pyrene diol epoxide

Because smoking increases a woman's risk of contracting bacterial vaginosis (BV), which is manifested by a reduction of vaginal lactobacilli and an overgrowth of anaerobic bacteria, chemicals contained in cigarette smoke were analyzed in vitro to determine their role in reducing lactobacilli. The result showed that trace amounts of benzo[a]pyrene diol epoxide (BPDE), which can be found in vaginal secretion of women who smoke, significantly increased phage induction in lactobacilli. This finding implies that smoking may reduce vaginal lactobacilli by promoting phage induction.

Generation of CD8+ T cell-generated suppressor factor and beta-chemokines by targeted iliac lymph node immunization in rhesus monkeys challenged with SHIV-89.6P by the rectal route

The targeted lymph node (TLN) immunization strategy was investigated in macaques, in order to determine the efficacy in generating secretory, systemic, and cellular immune responses, CD8+ T cell-generated suppressor factors, and beta-chemokines. TLN immunization of the rectal and genital mucosa-associated iliac lymph nodes (TILNs) was compared with axillary TLN immunization (TAxLN) using HIV-1 MN/LAI gp140env and SIV p27gag in alum. Significantly higher immune responses, as well as CD8+ T cell-generated anti-SIV factors and the beta-chemokines RANTES, MIP-1alpha, and MIP-1beta, were elicited by iliac as compared with axillary TLN immunization. The immune responses induced by TLN immunization were examined for their capacity to prevent rectal mucosal infection by the pathogenic dual-tropic SHIV-89.6P. Despite significant secretory, serum, cellular, and beta-chemokine responses, the macaques were infected by SHIV-89.6P. Whether the lack of protection was associated with the antigenic unrelatedness of SHIV-89.6P to the immunizing HIV-1 MN/LAI gp140 or to the virus utilizing CXCR4 to a much greater extent than CCR5, remains to be determined.

[A Study On Dental and Craniofacial Structure Of Normal Shanghai Adults Occlusio-II The Dental Facial Symmetry Analysis with Posterioanterior Cephalometric Roentgenography]

OBJECTIVE:To evaluate the dental facial symmetry in normal Shanghai adults occlusion with posterioanterior cephalometric roentgenography. METHODS:Posterioanterior films of the 92 adults subjects with normal occlusion were measured. Five facial midlines commonly used in posterioanterior cephalometric were analyzed according to the middle structure index and side middle structure index. The midline deviations were measured. RESULTS:The middle line through ANS and perpendicular to zygomaticofrontal line has less mean of middle structure index and side middle structure index. There are midline deviations in population with normal occlusion.CONCLUSION:The facial midline mentioned above was suitable for posterioanterior cephalometrics, but the reliability is not absolute. Normal occlusion also has midline deviations. The asymmetry of face was larger than that of dental occlusion.

Randomly amplified polymorphic DNA (RAPD) polymerase chain reaction assay for identification of Schistosoma mansoni strains sensitive or tolerant to anti-schistosomal drugs

The genetic differences between Schistosoma mansoni strains from different geographic areas that were reportedly resistant or sensitive to anti-schistosomal drugs were studied with randomly amplified polymorphic DNA (RAPD) and simple sequence repeat (SSR) polymerase chain reaction (PCR) assays. Of the 20 RAPD primers we chose, 19 showed the capacity to produce a medium to high level of amplification and 6 revealed difference PCR bands between drug-resistant and drug-sensitive strains. One particular primer, 5'-CAGCGACAAG-3', showed 2 major difference bands between praziquantel (PZQ)-resistant and PZQ-sensitive strains from the endemic area of Egypt. These results demonstrate that defined sequence primers could be applied as a useful tool for differentiating drug-resistant and -sensitive schistosome parasites in the field.

Heat shock proteins generate beta-chemokines which function as innate adjuvants enhancing adaptive immunity

Heat shock proteins (HSP) are widely distributed and highly immunogenic molecules. A novel property reported here is that stimulation with HSP70 of CD8-enriched T cells derived from naive non-human primates caused a dose-dependent increase in concentrations of the beta-chemokines RANTES, macrophage inflammatory protein (MIP)-1alpha or MIP-1beta. However, the concentrations of these beta-chemokines were greatly increased when the CD8 T cells derived from HSP70-immunized non-human primates were stimulated with HSP70. HSP linked to peptides or proteins combined generation of beta-chemokines with an adjuvant function by enhancing specific T cell proliferative responses and IgG and IgA antibodies. The beta-chemokine and adjuvant functions were also elicited by topical mucosal administration of HSP linked to an antigen. We postulate that microbial HSP can stimulate beta-chemokine production which may be responsible for innate adjuvanticity, as was found in cells eluted from normal rectal mucosal tissue, and constitutes a significant component of the mucosal-associated lymphoid system. Furthermore, stimulation of innate immunity may drive adaptive immunity and account for the protective effects of HSP against tumors and viruses.

Domain growth in ternary fluids: A level set approach

We analyze phase separation in ternary systems in the asymptotic hydrodynamic regime when the volume fractions and concentrations are constant. The multiphase Navier-Stokes equations are solved using a level set method. A new projection method was developed to treat multiple junctions for systems with more than two phases. It is found that surface tension ratios can alter the growth mechanism of a minority phase in the presence of two majority phases. When the minority phase wets the interface of the majority phases the domain growth rate of all three phases is initially similar to that of a symmetric binary fluid but slows down at later times.

In vitro inhibition of commercial douche products against vaginal microflora

Recently, vaginal douching has been associated with many health risks in women. The aim of this study was to analyze the effect of commercial douche products against various vaginal microorganisms, including lactobacilli. Seven commercial douches were tested against eight Lactobacillus clinical isolates and three type strains from the American Type Culture Collection. BV-associated bacteria included six strains of five genera: Gardnerella, Mobiluncus, Mycoplasma, Peptostreptococcus, and Ureaplasma. Two isolates of group B Streptococcus, and three species of Candida were also tested. The minimal inhibition concentrations and minimal contact times for these products against vaginal microorganisms were determined in broth cultures. Four antiseptic-containing douche products showed a strong inhibitory effect against all vaginal microorganisms tested with a short contact time (less than 1 min). Three vinegar-containing douche products selectively inhibited vaginal pathogens associated with bacterial vaginosis, group B streptococcal vaginitis, and candidiasis, but not lactobacilli. The antimicrobial effects of the commercial douche products varied among different brands and microbial species tested.

Isolation, cultivation, and characterization of Borrelia burgdorferi from rodents and ticks in the Charleston area of South Carolina

Twenty-eight Borrelia burgdorferi isolates from the Charleston, S.C., area are described. This represents the first report and characterization of the Lyme disease spirochete from that state. The isolates were obtained from December 1994 through December 1995 from the tick Ixodes scapularis, collected from vegetation, and from the rodents Peromyscus gossypinus (cotton mouse), Neotoma floridana (eastern wood rat), and Sigmodon hispidus (cotton rat). All isolates were screened immunologically by indirect immunofluorescence with monoclonal antibodies to B. burgdorferi-specific outer surface protein A (OspA) (antibodies H5332 and H3TS) and B. burgdorferi-specific OspB (antibodies H6831 and H614), a Borrelia (genus)-specific antiflagellin antibody (H9724), Borrelia hermsii-specific antibodies (H9826 and H4825), and two polyclonal antibodies (one to Borrelia species and another to B. burgdorferi). Six of the isolates were analyzed by exposing Western blots to monoclonal antibodies H5332, H3TS, H6831, and H9724. All isolates were also analyzed by PCR with five pairs of primers known to amplify selected DNA target sequences specifically reported to be present in the reference strain, B. burgdorferi B-31. The protein profiles of six of the isolates (two from ticks, one from a cotton mouse, two from wood rats, and one from a cotton rat) also were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. We conclude that the 28 Charleston isolates are B. burgdorferi sensu stricto based on their similarities to the B. burgdorferi B-31 reference strain.

In vitro inhibition of commercial douche products against vaginal microflora

Recently, vaginal douching has been associated with many health risks in women. The aim of this study was to analyze the effect of commercial douche products against various vaginal microorganisms, including lactobacilli. Seven commercial douches were tested against eight Lactobacillus clinical isolates and three type strains from the American Type Culture Collection. BV-associated bacteria included six strains of five genera: Gardnerella, Mobiluncus, Mycoplasma, Peptostreptococcus, and Ureaplasma. Two isolates of group B Streptococcus, and three species of Candida were also tested. The minimal inhibition concentrations and minimal contact times for these products against vaginal microorganisms were determined in broth cultures. Four antiseptic-containing douche products showed a strong inhibitory effect against all vaginal microorganisms tested with a short contact time (less than 1 min). Three vinegar-containing douche products selectively inhibited vaginal pathogens associated with bacterial vaginosis, group B streptococcal vaginitis, and candidiasis, but not lactobacilli. The antimicrobial effects of the commercial douche products varied among different brands and microbial species tested.

A study on PCR for detecting infection with M. leprae

OBJECTIVE

So far, it has not been established a satisfactory method for early diagnosis and studying on epidemiology for leprosy, we want to develop a molecular biological method for solving this point.

MATERIALS AND METHODS

Based on the M. leprae gene coding groEL, 65 kD and 16S rRNA, three polymerase chain reactions were developed by using Plikaytis', Woods' and Pattyn's procedures. It was optimized that the experimental parameters for each PCR, and a comparative study on practivity among three PCRs was also conducted for practical purpose.

RESULTS AND CONCLUSION

For detecting infection with M. leprae, all of PCRs established by us were highly sensitive and specific, but for practical purpose, the Woods' PCR optimized by us ought to be chosen firstly.

[Effection of children airway foreign bodies on blood acid-base disturbances]

OBJECTIVE

To explore the effects of children airway foreign bodies on blood acid-base disturbances.

METHOD

To detect the blood-gas and electrolyte of 50 cases by children airway foreign bodies (test group), they were compared with 50 cases normal children (control group). To calculate anion gap (AG), to determine types of acidbase disturbances.

RESULT

The blood-gas and K+ were significant difference between that two groups. In the test group, there were 25 simple and 19 mixed acid-base disturbances; 6 acid-base balances. There were 31 high AG, 18 normal AG, one low AG.

CONCLUSION

Children airway foreign bodies can cause acid-base disturbances. It was major in simple metabolic acidosis and mixed metabolic acidosis with respiratory alkalosis, it was more in high AG-metabobic acidosis.

[Three dimensional finite element analysis of effects on composite resin for filling in various cavity margin design]

OBJECTIVE

To evaluate the stress distribution of different angles of cavity margins with composite resin filling.

METHODS

The stress distributions of different angles of cavity margins of class I cavity of molars were analyzed by the method of three dimensional finite element. The cavity was filled with composite resin and the stress vertical force and lateral force was calculated.

RESULTS

In the 5 designed different cavity margin angles, the vertical forces and lateral forces were 18.757 MPa and 22.309 MPa respectively when the angle is 90 degrees; when the angles were 75 degrees and 60 degrees, they were 10.580 MPa, 14.265 MPa and 9.025 MPa, 13.230 MPa respectively. The vertical forces and lateral forces produced by the surface of composite resin while being stressed were up to 18.757 MPa and 22.309 MPa. The forces of the second layer evidently reduced to 2.586 MPa and 6.8 MPa.

CONCLUSION

When fill the molars with resin in clinic, the angles of cavity margins should be prepared with the slopes of 60 degrees to 75 degrees.

Allo-immunization elicits CD8+ T cell-derived chemokines, HIV suppressor factors and resistance to HIV infection in women

We assessed the potential for an allogeneic-based vaccine against HIV infection in women who were allo-immunized with their partners' mononuclear leucocytes to prevent spontaneous recurrent abortion. Within 1 month of allo-immunization, there was significant upregulation in the concentrations of CD8 cell-derived suppressor factor activity, RANTES, and macrophage inflammatory proteins 1alpha and 1beta. Allo-immunization also downregulated the proportion of cells with CCR5 and CXCR4 receptors. We also found a dose-dependent decrease in HIV infectivity of CD4+ cells in vitro after allo-immunization with both primary and T-cell line adapted HIV-1. This study provides a rational basis for an alternative or complementary strategy of allo-immunization against HIV infection.

[Correlation of conformational change with enzyme activity of glucose isomerase in denaturants monitored with high performance liquid chromatography]

Glucose isomerase (GI) can catalyze in vitro the isomerization of D-glucose to D-fructose. So it is an extremely important industrial enzyme in the commercial conversion of starch to high fructose syrups. In the previous papers, we have purified and characterized the enzyme from streptomyces diastaticus M1033 of China and obtained the crystal structures by X-ray. In this paper, a method for measurement of the dynamic conformational change procedure of glucose isomerase in various concentrations of denaturants by HPLC has been established. At first the relative molecular mass of GI in solution is measured by HPLC on PROTEIN PAK 300SW (7.5 mm i.d. x 30 cm) column. The relative molecular mass of GI is about 150,000. So GI exists as tetramer in the solution without denaturants. In 0-5 mol/L guanidine hydrochloride, incubated at 30 degrees C for 30 min, GI is gradually dissociated into monomer, and at the same time its activity gradually disappears. In various concentrations of urea and incubation at 30 degrees C for 30 min (or 60 degrees C for 1 h), the results are different from that in guanidine, because the monomers peaks of GI is not found. Only in certain concentrations of urea, the small dimer peaks of GI is found, but the activity of GI significantly disappears. Moreover as the increase of the urea concentration, the retention time of tetramer peak is gradually decreases. From the fluorescence spectra, we found the conformation of GI changed in the solution of urea. So perhaps in urea, the conformation of GI become a little unfolded, and the active region is partly damaged, which makes GI partly inactive. Dissociation into inactive monomers and conformation partly unfolding are all the reason of GI inactivation in denaturants.