Modular organization of occipito-temporal pathways: cortical connections between visual area 4 and visual area 2 and posterior inferotemporal ventral area in macaque monkeys

The modular organization of cortical pathways linking visual area 4 (V4) with occipital visual area 2 (V2) and inferotemporal posterior inferotemporal ventral area (PITv) was investigated through an analysis of the patterns of retrogradely labeled cell bodies after injections of tracers into V4 and PITv. Although cytochrome oxidase or other stains have failed to yield reliable independent anatomical markers for cortical modules beyond V1 and V2, V4 and PITv seem to have modular compartments with specific patterns of cortico-cortical connectivity. Tracer injections of V4 labeled cells in V2 (1) thin stripes exclusively, (2) interstripes exclusively, or (3) specific combinations of interstripe and thin stripe subcompartments. These labeling patterns suggest (1) that there is a complicated organization of inputs to V4, (2) that projections from V2 to V4 display a submodular selectivity, and (3) that projections from V2 to V4 display some degree of cross-stream convergence. Consistent with this framework, extensive regions of PITv provide feedback projections to interstripe-recipient portions of V4, whereas more restricted portions of PITv provide feedback to thin stripe-recipient portions of V4. Similarly, the feedforward projection from V4 to PITv often arose from multiple cell clusters across a wide expanse of V4. When distinguishable fluorescent tracers were injected into two PITv sites separated by 3-5 mm, a variety of projection patterns was observed in V4. In most cases, labeled cells were found in multiple, interdigitating, nonoverlapping clusters of 1-3 mm width, whereas in other cases the two labeled fields were highly intermixed. These results suggest that V4 and PITv contain functional modules that can be characterized by the specific patterns of segregated and convergent projections they receive from lower cortical areas. These specific patterns of intercortical input, in conjunction with intrinsic cortical circuitry, may endow extrastriate cortical neurons with new and more complex receptive field properties.

Involvement of disulphide bonds in the renal sodium/phosphate co-transporter NaPi-2

The rat renal brush border membrane sodium/phosphate co-transporter NaPi-2 was analysed in Western blots with polyclonal antibodies raised against its N-terminal and C-terminal segments. Under reducing conditions, proteins of 45-49 and 70-90 kDa (p45 and p70) were detected with N-terminal antibodies, and proteins of 40 and 70-90 kDa (p40 and p70) were detected with C-terminal antibodies. p40 and p45 apparently result from a post-translational cleavage of NaPi-2 but remain linked through one or more disulphide bonds. Glycosidase digestion showed that both polypeptides are glycosylated; the cleavage site could thus be located between Asn-298 and Asn-328, which have been shown to constitute the only two N-glycosylated residues in NaPi-2. In the absence of reducing agents, both N-terminal and C-terminal antibodies detected p70 and a protein of 180 kDa (p180), suggesting the presence of p70 dimers. Much higher concentrations of beta-mercaptoethanol were required to produce a given effect in intact membrane vesicles than in solubilized proteins, indicating that the affected disulphide bonds are not exposed at the surface of the co-transporter. Phosphate transport activity decreased with increasing concentrations of reducing agents [beta-mercaptoethanol, dithiothreitol and tris-(2-carboxyethyl)phosphine] and was linearly correlated with the amount of p180 detected. The target sizes estimated from the radiation-induced loss of intensity of p40, p70 and p180 were all approx. 190 kDa, suggesting that NaPi-2 exists as an oligomeric protein in which the subunits are sufficiently close to one another to allow substantial energy transfer between the monomers. When protein samples were pretreated with beta-mercaptoethanol [2.5% and 5% (v/v) to optimize the detection of p40 and p70] before irradiation, target sizes estimated from the radiation-induced loss of intensity of p40 and p70 were 74 and 92 kDa respectively, showing the presence of disulphide bridges in the molecular structure of NaPi-2.

[The change of trace elements content in hair during the period of gestation]

Study on trace elements content change in hair during the period of gestation for 52 lying-in women was performed. The quantitative results for 7 elements have been obtained and the change tendencies for other 7 elements without standard value have been observed on the basis of a self comparison method for each individual.

Association of BRCA1 with Rad51 in mitotic and meiotic cells

BRCA1 immunostaining reveals discrete, nuclear foci during S phase of the cell cycle. Human Rad51, a homolog of bacterial RecA, behaves similarly. The two proteins were found to colocalize in vivo and to coimmunoprecipitate. BRCA1 residues 758-1064 alone formed Rad51-containing complexes in vitro. Rad51 is also specifically associated with developing synaptonemal complexes in meiotic cells, and BRCA1 and Rad51 were both detected on asynapsed (axial) elements of human synaptonemal complexes. These findings suggest a functional interaction between BRCA1 and Rad51 in the meiotic and mitotic cell cycles, which, in turn, suggests a role for BRCA1 in the control of recombination and of genome integrity.

Association of U2 snRNP with the spliceosomal complex E

In metazoans, the E complex is operationally defined as an ATP-independent spliceosomal complex that elutes as a single peak on a gel filtration column and can be chased into spliced products in the presence of an excess of competitor pre-mRNA. The A complex is the first ATP-dependent functional spliceosomal complex. U1 snRNP first binds tightly to the 5'splice site in the E complex and U2 snRNP first binds tightly to the branch site in the A complex. In this study, we have generated and characterized a monoclonal antibody (mAb 4G8) directed against SAP 62, a component of U2 snRNP and a subunit of the essential mammalian splicing factor SF3a. We show that this antibody is highly specific for SAP 62, detecting only SAP 62 on Western blots and immunoprecipitating only SAP 62 from nuclear extracts. The anti-SAP 62 antibody also immunoprecipitates U2 snRNP and the A complex. Significantly, however, we find that the E complex is also efficiently immunoprecipitated by the anti-SAP 62 antibody. This antibody does not cross-react with any E complex-specific components, indicating that SAP 62 itself is associated with the E complex. To determine whether other U2 snRNP components are associated with the E complex, we used antibodies to the U2 snRNP proteins B"and SAP 155. These antibodies also specifically immunoprecipitate the E complex. These observations indicate that U2 snRNP is associated with the E complex. However, we find that U2 snRNP is not as tightly bound in the E complex as it is in the A complex. The possible significance of the weak association of U2 snRNP with the E complex is discussed.

Characterization of embryonic stem-like cell lines derived from embryoid bodies

Embryoid bodies (EB) were formed by TT2 embryonic stem (ES) cells in vitro. ES-like cell lines (ESLC) were established by culturing cells obtained by disaggregation of EB at 4, 8 and 20 days after culture, and designated ESLC4, ESLC8 and ESLC20, respectively. Flow cytometric analysis indicated that the cell surface expression of Le(a) on ESLC was less than that of original TT2 ES cells, but the expression of L-CAM was comparable. After suspension culture, all of the ESLC cells formed cystic EB in vitro. In addition, some ESLC4- and ESLC8-derived EB showed signs of beating. Although coat color chimeras were able to be produced with ESCL4 at a lower rate than parental ES cells, the cells did not contribute to germ line cells in chimeras. These results suggest that the ESLC had less pluripotent than parental ES cells and also that EB formation is not useful in obtaining pluripotent cells.

Instability of CHO chromosomes containing interstitial telomeric sequences originating from Chinese hamster chromosome 10

We identified a marker chromosome in the CHO K1 cell line containing amplifications of interstitial telomeric sequences originating from Chinese hamster chromosome 10. Analysis of the progression of this chromosome in two subclones of CHO K1 revealed sensitivity of one amplicon to chromosome breakage, resulting in telomere function at the break site. In addition, two more marker chromosomes, both containing amplifications of interstitial telomeric sequences from chromosome 10, were formed during karyotypic evolution of the CHO K1 subclones. The presence of some of the marker chromosomes was also identified in the radiosensitive xrs 5 cell line derived from CHO K1. These results indicate instability of CHO K1 chromosomes containing interstitial telomeric sequences originating from Chinese hamster chromosome 10.

Mechanisms of induction of chromosomal aberrations and their detection by fluorescence in situ hybridization

Fluorescence in situ hybridization (FISH) technique using chromosome specific probes has revolutionized the field of radiation cytogenetics in the last few years. Some of the new insights on the origins of radiation induced chromosome aberrations in human, mouse and Chinese hamster, using FISH are reviewed in this paper.

[Establishment of human amnion cell mutagenesis system by using a shuttle vector pS189]

Using transient shuttle vector pS189, we established a subclone human amnion cell (FL) mutagenesis detection system, and we detected the mutation specificity of N-methy-N'-nitro-N-nitrosoguanidine (MNNG) in this system. The spontaneous mutant frequency of target gene supF was 1.7 x 10(-5) and MNNG-induced mutant frequency was increased with dosage. The results from 0.8% agarose gel electrophoresis, PCR, PCR-single strand conformation polymorphism (PCR-SSCP) analysis showed that MNNG-induced 89% mutants were point mutants. These results indicated that this system can be used to detect and study the mutagenesis mechanism of potential mutagens.

Task complexity in emergency medical care and its implications for team coordination. LOTAS Group. Level One Trauma Anesthesia Simulation

To elicit components of task complexity in emergency medical care, a study was conducted to contrast one medical procedure with two levels of task urgency in trauma patient resuscitation. Videotapes of actual resuscitation were reviewed to extract task characteristics of the procedure. Two levels of urgency were compared in the following areas: patient status, technical difficulty of tasks, the amount of available patient monitoring information, and the pace of work. Four components of task complexity in emergency medical care were identified: multiple and concurrent task, uncertainty, changing plans, and compressed work procedures and high workload. These components of task complexity pose challenges to team functions and can lead to problems in team coordination, such as conflicts in goals, tasks, and access to the patient. Training to increase explicit communications and improvements in the design of work procedures are necessary in order to meet the challenges of task complexity.

Comparison of self-reporting of deficiencies in airway management with video analyses of actual performance. LOTAS Group. Level One Trauma Anesthesia Simulation

We compared the performance deficiencies of airway management captured by three types of self-reports with those identified through video analysis. The three types of self-reports were the anesthesia record (a patient record constructed during the course of treatment), the anesthesia quality assurance (AQA) report (a retrospective report as a part of the trauma center's quality assurance process), and a posttrauma treatment questionnaire (PTQ), which was completed immediately after the case for the purposes of this research. Video analysis of 48 patient encounters identified 28 performance deficiencies related to airway management in 11 cases (23%). The performance deficiencies took the form of task omissions or practices that lessened the margin of patient safety. In comparison, AQA reports identified none of these performance deficiencies, the anesthesia records identified 2 (of 28), and the PTQs suggested contributory factors and corrective measures for 5 deficiencies. Furthermore, video analysis provided information about the context of and factors contributing to the identified performance deficiencies, such as failures in adherence to standard operating procedures and in communications.

Expression of extracellular matrix macromolecules around demineralized freeze-dried bone allografts

In the present study histochemical techniques were used to identify specific macromolecular components of the extracellular matrix associated with the tissue reaction to demineralized freeze-dried bone allografts (DFDBA) placed under barrier membranes for ridge augmentation. Small biopsies were obtained from tissues underneath the membranes at various times after placement of the DFDBA and processed for routine immunohistochemistry. Sections were stained with antibodies to osteocalcin, collagen type I, collagen type III, decorin, and biglycan. Non-immune serum, irrelevant antibodies, and omission of the primary antibodies served as negative controls. Histologic examination of the biopsies revealed allograft particles surrounded by well-formed fibrous connective tissue with little or no evidence of new bone formation. Vital autogenous bone fragments were present in the peripheral portions of the biopsies and served as positive controls for comparative purposes with the DFDBA particles. Only 7 out of the 20 biopsies studied were found to have any signs of bone formation around the DFDBA particles and in these such bone formation was irregular and inconsistent around the DFDBA particles. Around the periphery of the allograft particles, osteocalcin, collagen type I, collagen type III, decorin, and biglycan all showed relatively strong staining. Osteocalcin staining was also noted within the vital bone matrix but not in the surrounding fibrous connective tissue. Decorin, biglycan, collagen type I, and collagen type III were also found within the vital bone matrix. None of these antibodies stained the DFDBA particles. The unremarkable osteogenic response of the tissues to the DFDBA particles after healing periods of up to 12 months raises questions as to the predictability of these agents in inducing new bone.

Effect of receptor-ligand affinity on the strength of endothelial cell adhesion

The objective of this study was to determine the effect of receptor-ligand affinity on the strength of endothelial cell adhesion. Linear and cyclic forms of the fibronectin (Fn) cell-binding domain peptide Arg-Gly-Asp (RGD) were covalently immobilized to glass, and Fn was adsorbed onto glass slides. Bovine aortic endothelial cells attached to the surfaces for 15 min. The critical wall shear stress at which 50% of the cells detached increased nonlinearly with ligand density and was greater with immobilized cyclic RGD than with immobilized linear RGD or adsorbed Fn. To directly compare results for the different ligand densities, the receptor-ligand dissociation constant and force per bond were estimated from data for the critical shear stress and contact area. Total internal reflection fluorescence microscopy was used to measure the contact area as a function of separation distance. Contact area increased with increasing ligand density. Contact areas were similar for the immobilized peptides but were greater on surfaces with adsorbed Fn. The dissociation constant was determined by nonlinear regression of the net force on the cells to models that assumed that bonds were either uniformly stressed or that only bonds on the periphery of the contact region were stressed (peeling model). Both models provided equally good fits for cells attached to immobilized peptides whereas the peeling model produced a better fit of data for cells attached to adsorbed Fn. Cyclic RGD and linear RGD both bind to the integrin alpha v beta 3, but immobilized cyclic RGD exhibited a greater affinity than did linear RGD. Receptor affinities of Fn adsorbed to glycophase glass and Fn adsorbed to glass were similar. The number of bonds was calculated assuming binding equilibrium. The peeling model produced good linear fits between bond force and number of bonds. Results of this study indicate that 1) bovine aortic endothelial cells are more adherent on immobilized cyclic RGD peptide than linear RGD or adsorbed Fn, 2) increased adhesion is due to a greater affinity between cyclic RGD and its receptor, and 3) the affinity of RGD peptides and adsorbed Fn for their receptors is increased after immobilization.

Radioprotection of beta-carotene evaluated on mouse somatic and germ cells

In the present paper, the protective effect of beta-carotene was evaluated after whole body exposure of mice to 2 Gy of X-rays. Splenocytes, reticulocytes, bone marrow cells and spermatids were evaluated for the frequency of micronuclei (MN) induced by X-rays. Mice were treated (gavage) with beta-carotene (10, 25 and 50 mg/kg b.w.) for 5 consecutive days and, 4 h after the last treatment, the animals were irradiated. The results obtained showed different frequencies of X-ray-induced-MN between different cell populations analysed and also different response of these cells to the beta-carotene treatment. The radioprotective effect of beta-carotene was observed in splenocytes, reticulocytes, and spermatids but not in bone marrow cells. No dose-response relationship for beta-carotene was detected. The time of sampling, the sensitivity of the cells as well as the antioxidant activity of beta-carotene are discussed as important factors for the radioprotective action of this provitamin.

Analysis of micronuclei induced by 1,3-butadiene and its metabolites using fluorescence in situ hybridization

In our previous study, micronuclei (MN) were induced in bone marrow cells of mice following inhalation exposure to 1300 ppm of 1,3-butadiene (BD) for 6 h per day on 5 consecutive days, and in splenocytes of mice and rats treated intraperitoneally with 80 mg/kg 1,2-epoxybutene (EB) and 30 mg/kg 1,2,3,4-diepoxybutane (DEB), respectively. In the present study, the nature of MN induced by BD, EB and DEB was analyzed by means of fluorescence in situ hybridization (FISH) using mouse minor satellite DNA and rat satellite I DNA as probes. Percentages of MN with centromere signals (MN+) measured following exposures to BD, EB and DEB indicate that these agents are predominantly clastogens. Frequencies of MN+ per 1000 cells suggest that BD, EB and DEB are not only strong clastogens, but also weak aneugens in mice. The weak aneugenic effect of EB and DEB was not observed in rats. Analysis of the number of centromere signals in individual MN, and the size distribution of MN with centromere signals in EB- and DEB-treated animals, and in animals exposed to the positive controls diethylstilbestrol (DES) and mitomycin C (MMC) led to the following conclusions: (1) analysis of MN for the number of centromere signals may be a useful indicator for identifying chemicals with aneugenic properties; (2) there is no correlation between the size of MN and their origin (i.e., chromosome loss/gain or fragment).

Spontaneous and radiation-induced chromosomal breakage at interstitial telomeric sites

The Chinese hamster genome contains a total of 18 cytologically detectable arrays of interstitial telomeric sequences. A combination of G-banding and two-colour fluorescence in situ hybridization revealed that 25 out of 27 (93%) breakpoints of spontaneously occurring terminal deletions in four immortalized Chinese hamster cell lines were located in chromosomal regions containing interstitial telomeric sequences. Each of the four immortalized Chinese hamster cell lines expressed telomerase. Radiation experiments revealed the sensitivity of interstitial telomeric sequences to radiation-induced chromosomal breakage in all telomerase-positive cell lines. However, radiation-induced chromosomal breakage at interstitial telomeric sites in non-transformed, primary Chinese hamster cells was almost non-existent. Telomerase activity in primary Chinese hamster cells was not detected. These results indirectly suggest that interstitial telomeric sites represent a favourable substrate for chromosomal healing.

Control of retinoic acid receptor expression in mouse melanoma cells by cyclic AMP

Retinoic acid receptor (RAR) alpha and gamma mRNAs were constitutively expressed in B16 melanoma cells with or without retinoic acid (RA) treatment. RAR beta mRNA, however, was significantly expressed only after exposure to RA. Induction of RAR beta by RA occurred within 1 h and was not inhibited by cycloheximide (i.e., did not require new protein synthesis). All three RAR mRNA levels were dramatically decreased with 8-bromo-cyclic AMP treatment and could not be rescued by addition of RA. Analysis of RAR gamma revealed that this decrease occurred within 1 h of exposure to 8-bromo-cyclic AMP and was not blocked by simultaneous treatment with cycloheximide. The stability of RAR gamma mRNA was not altered by cyclic AMP treatment. Nuclear extracts from 8-bromo-cyclic AMP-treated cells showed a large decrease in protein binding to a retinoic acid response element (RARE) oligonucleotide compared to control cells. This correlated with a marked reduction of RA-stimulated RARE-reporter gene activity in transfected cells which were treated with cyclic AMP. Pretreatment of B16 cells with cyclic AMP prior to RA addition dramatically reduced induction of PKC alpha, an early marker of RA-induced cell differentiation. Thus, cyclic AMP can antagonize the action of RA most likely via its ability to inhibit RAR expression.

Phosphate deprivation induces overexpression of two proteins related to the rat renal phosphate cotransporter NaPi-2

Polyclonal antibodies were raised in rabbits against the C-terminal portion of the rat renal brush-border membrane sodium/phosphate cotransporter NaPi-2. Antibody specificity and molecular sizes of proteins related to NaPi-2 were assayed by Western blot analysis. Proteins of 40 and 70-75 kDa (p40 and p70) were immunodetected in rat and mouse brush-border membranes and proteins of 72 and 82 kDa were detected in rabbit. The absence or presence of beta-EtSH in the samples before electrophoresis greatly influenced the immunodetection profile of the rat proteins. Since the 40 kDa protein (p40) can only be detected under reducing conditions, it probably originates from reduction of disulfide bonds in p70. Tryptic cleavage of p40 and p70 revealed identical protein fragments showing the close structural identity of those proteins. Both proteins were more abundant in the outer cortex portion of the rat kidney than in the juxtamedullary portion. Furthermore, rats fed a low-phosphate diet for 24 h showed a 20- and 14-fold increase in the amount of p40 and p70, respectively, compared to control rats, showing that the adaptation to P(i) deprivation by increasing renal phosphate reabsorption is not only the result of overproduction of p70, as previously shown, but is also due to the novel p40 which most probably derives from p70.

Late acquisition of hyporesponsiveness to lipopolysaccharide by Mycobacterium avium-infected human macrophages in producing tumor necrosis factor-alpha but not interleukin-1 beta and -6

To investigate whether infection with Mycobacterium avium modifies the cytokine response of human macrophages (Mphi) to lipopolysaccharide (LPS), the release of interleukin (IL)-1 beta, IL-6, and tumor necrosis factor (TNF)-alpha was determined in infected and uninfected Mphi, unstimulated or stimulated with LPS. In unstimulated Mphi, the release of IL-1 beta and IL-6 increased with the progress of infection while that of TNF-alpha progressively decreased. When Mphi were stimulated with LPS, IL-1 beta and IL-6 levels were always higher in infected than in uninfected cells, but levels of TNF-alpha significantly decreased in infected Mphi. A similar trend was obtained for TNF-alpha mRNA expression. Altogether, these results indicate that infected Mphi react to LPS stimulus with enhanced levels of IL-1 beta and IL-6 but are unable to restore the production of TNF-alpha impaired by the growth of the intracellular mycobacteria.

Effects of melatonin implants on winter fur growth and testicular recrudescence in adult male raccoon dogs (Nyctereutes procyonoides)

The effects of melatonin implants were investigated on winter fur growth, monitored by counting growing and mature hairs per bundle and testicular recrudescence, judged by testis width, score count of spermatogenesis, and serum testosterone in the adult male raccoon dogs. Melatonin administration in July highly elevated melatonin concentrations in serum and urine and induced an earlier decrease in prolactin secretion (August in the treated group vs September in the control group), winter fur growth (July-beginning of November in the treated group vs. August-end of November in the control group) and testicular recrudescence (October in the treated group vs. November in the control group). In the control animals, urinary excretion of melatonin between 1500-0900 hr increased during autumn followed by a rapid fall in winter. The increase from July (1.8 +/- 0.4 ng) to August (3.9 +/- 0.5 ng) and the subsequent unchanged levels until October coincided with the period of winter fur growth. The further increase in November (6.5 +/- 1.2 ng) coincided with the significant elevation in both testis width and score count of spermatogenesis. These results suggest a role of the increase in endogenous melatonin secretion during autumn in the growth of winter fur and testicular recrudescence in this species under natural conditions. Relatively high serum concentrations of prolactin were shown in two animals, one in the control group and another in the treated group. However, the parameters for testis and winter fur growth in the two cases were similar to those in the remainder of the animals. Thereby, the role of prolactin in the winter fur growth and the initiation of testicular recrudescence, if it is truly involved, is manifested through its decreasing secretion rather than the actual blood concentrations.