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.

Type frequency and antimicrobial susceptibility of Mycobacterium avium-intracellulare complex strains isolated in Italy from AIDS and non-AIDS patients

Typing of the glycopeptidolipid antigens performed by thin layer chromatography on 59 Mycobacterium avium-intracellulare (MAC) strains isolated in Italy from AIDS patients showed that the most frequent types were 1, 4, 3, 8, and 21 (24, 19, 14, 14 and 8% of the strains, respectively). Among non-AIDS patients, types 1, 4 and 8 were also frequently found. The antimicrobial susceptibility tested in agar and/or liquid media to a panel of drugs indicated in clofazimine and rifabutin effective agents against both AIDS and non-AIDS strains. The data obtained show that MAC type distribution in Italy appears to be different from that reported for other countries. No major differences in drug susceptibility between AIDS and non-AIDS related strains were found.

Generation of mouse chromosome painting probes by DOP-PCR amplification of microdissected meiotic chromosomes

We describe here the development of four sets of painting probes for mouse chromosomes 1 and 13, 2 and 8, 6 and 15, and X and Y by degenerate oligonucleotide-primed polymerase chain reaction (DOP-PCR) amplification of 10-20 copies of microdissected male meiotic chromosomes. The X,Y probe was obtained from the X-Y bivalent of diakinesis/metaphase I complements of mice with a normal karyotype, whereas the other probes were derived from tri- or quadrivalents in diakinesis/metaphase I of two reciprocal translocations, T(1;13)70H and T(2;8)2Wa, and one inversion heterozygote carrying a small deletion, In(6;15)Rb1Ald del6(15)1Wa. The specificity of these probes was established by fluorescence in situ hybridization (FISH) to meiotic and mitotic metaphase complements. The chromosomes painted by these probes could be identified by single or multicolor FISH.

Development of DNA libraries specific for Chinese hamster chromosomes 3, 4, 9, 10, X, and Y by DOP-PCR

In a previous study of ours, DNA libraries specific for Chinese hamster chromosomes 1, 2, 3, 5, 6, 7, and 8 were constructed by single laser flow sorting and the linker adapter PCR method. Since a single laser flow sorting of chromosomes is based on chromosome size, it is difficult to separate chromosomes of equal size, such as chromosome 3 and the X chromosome. This problem can be circumvented by bivariate flow sorting. In the present study, we have used bivariate flow sorting of Chinese hamster chromosomes and the degenerate oligonucleotide-primed polymerase chain reaction (DOP-PCR) for generating DNA libraries specifically for chromosomes 3, 4, 9, 10, X, and Y. Fluorescence in situ hybridization (FISH) analyses indicate that the probe libraries are highly specific and can be applied to various cytogenetic studies.

Cytochemical localization of reserves during seed development in Arabidopsis thaliana under spaceflight conditions

Successful development of seeds under spaceflight conditions has been an elusive goal of numerous long-duration experiments with plants on orbital spacecraft. Because carbohydrate metabolism undergoes changes when plants are grown in microgravity, developing seed storage reserves might be detrimentally affected during spaceflight. Seed development in Arabidopsis thaliana plants that flowered during 11 d in space on shuttle mission STS-68 has been investigated in this study. Plants were grown to the rosette stage (13 d) on a nutrient agar medium on the ground and loaded into the Plant Growth Unit flight hardware 18 h prior to lift-off. Plants were retrieved 3 h after landing and siliques were immediately removed from plants. Young seeds were fixed and processed for microscopic observation. Seeds in both the ground control and flight plants are similar in their morphology and size. The oldest seeds from these plants contain completely developed embryos and seed coats. These embryos developed radicle, hypocotyl, meristematic apical tissue, and differentiated cotyledons. Protoderm, procambium, and primary ground tissue had differentiated. Reserves such as starch and protein were deposited in the embryos during tissue differentiation. The aleurone layer contains a large quantity of storage protein and starch grains. A seed coat developed from integuments of the ovule with gradual change in cell composition and cell material deposition. Carbohydrates were deposited in outer integument cells especially in the outside cell walls. Starch grains decreased in number per cell in the integument during seed coat development. All these characteristics during seed development represent normal features in the ground control plants and show that the spaceflight environment does not prevent normal development of seeds in Arabidopsis.

Expression of gamma-glutamyl transpeptidase during pouch carcinogenesis is not oncofetal

gamma-glutamyl transpeptidase (GGT) is not histochemically detectable in normal adult hamster pouch epithelium but markedly increased during pouch carcinogenesis. The possibility that the increase in GGT activity during pouch carcinogenesis reflects dedifferentiation of cells remains to be answered. The distribution of GGT in fetal and neonatal hamster tissues is unknown. The objective of this study was to determine GGT activity histochemically during hamster pouch development and during development of hamster oral and peri-oral structures, and several extra-oral tissues and organs. High GGT activity was seen mainly in epithelial cells exhibiting marked secretory or absorptive functions. Occasionally, GGT activity was also seen in mesenchymal cells. No GGT activity was noted at any stage of pouch development. The results suggest that the expression of GGT during pouch carcinogenesis represents an acquired phenotype instead of re-expression of a phenotype that is present during normal embryonic development. The results also support the hypothesis that GGT plays an important role in transportation.

Effects of melatonin implants in spring on testicular regression and moulting in adult male raccoon dogs (Nyctereutes procynoides)

Six male raccoon dogs were treated with constant-release implants of melatonin on 29 March, when the animals still had mature spermatozoa and a winter coat. Six untreated animals served as controls. High serum concentrations of melatonin were found in the treated animals throughout the study period (182.2 and 38.5 pg ml-1 in April and August, respectively). The high serum concentrations of prolactin in April and May (18.9 and 15.7 ng ml-1, respectively) in the controls were not seen in the treated animals. Testicular regression, judged by width of the testis and stage of spermatogenesis, was slowed after melatonin administration. Testis width from April to June and stage of spermatogenesis in May and June were greater in the treated animals than in the controls; however, from July onwards the differences between the two groups were no longer significant. Serum concentrations of testosterone remained low (below the detection limit in most cases) in both treated and control animals throughout the study period. Melatonin treatment also affected moulting, which was assessed by changes in the number of growing and mature underfur hairs per bundle and the percentage of bundles with a growing guard hair. The treated animals showed a more rapid shedding of mature underfur hairs and growth of new underfur hairs 6 weeks after melatonin implantation compared with the controls.(ABSTRACT TRUNCATED AT 250 WORDS)

[Hemodynamic changes in portal system after transjugular intrahepatic portosystemic shunts (TIPS)]

In this study portal venous flow (PVF), splenic venous flow (SPVF), hepatic artery volume (HAV), and portal pressure were measured before and after TIPS in 11 patients with portal hypertension. The results were compared with those of normal controls. In the normal controls PVF averaged 947.2 +/- 133.4ml/min, SPVF 239.6 +/- 116.3ml/min, and HAV 241.6 +/- 78.8ml/min. In the TIPS group before and after TIPS, PVF was 883.2 +/- 233.4ml/min vs. 958.7 +/- 185.2ml/min; SPVF was 448.9 +/- 111.6ml/min vs. 333.1 +/- 101.5ml/min; HVP was 225.3 +/- 122.7ml/min vs. 249.3 +/- 103.8ml/min. Portal pressure dropped from 3.94kPa +/- 0.46 to 2.52 +/- 0.60kPa after TIPS. We conclude that in patients after TIPS portal pressure drops blood flow in the truck of the portal vein increases, flow of hepatic tissue decreases, and blood flow in splenic vein decreases. Blood flow in hepatic aftery was not significantly changed.

DNA ligase I mediates essential functions in mammalian cells

DNA replication, repair, and recombination are essential processes in mammalian cells. Hence, the application of gene targeting to the study of these DNA metabolic pathways requires the creation of nonnull mutations. We have developed a method for introducing partially defective mutants in murine embryonic stem cells that circumvents the problem of cellular lethality of targeted mutations at essential loci. Using this approach, we have determined that mammalian DNA ligase I is essential for cell viability. Thus, DNA ligases II and III are not redundant with DNA ligase I for the function(s) associated with cell proliferation. Partial complementation of the lethal DNA ligase I null mutation allowed the creation of deficient embryonic stem cell lines. We found that a wild-type DNA ligase I cDNA, as well as a variant DNA ligase I cDNA, was able to rescue the lethality of the homozygous null mutation, whereas an N-terminal deletion mutant consisting of the minimal DNA ligase I catalytic domain was not. This observation demonstrates that sequences outside the DNA ligase I catalytic domain are essential for DNA ligase I function in vivo.

Fractal dimension of exon and intron sequences

In this paper, the concept of fractal is applied to describe the features of nucleotide sequences. We introduce the mapping from nucleotide sequences to two-dimensional metric space. Then we use this mapping to study quantitatively the self-similarity of exon and intron sequences in different scales. We find that self-similarity exists in the geometrical range and main range of a nucleotide sequence and define the fractal dimension in these ranges. The results show that the fractal properties of exon sequences are quite different from those of introns, reflecting their difference in structure and function. The fractal dimension of the geometrical range may be used to predict the exon regions of a raw nucleotide sequence.

Regulation of a muscle-specific transgene by retinoic acid

Retinoic acid (RA) has been shown to have variable effects on myogenic differentiation in cell culture. The application of RA on primary cultures of embryonic somites, limb buds, and neonatal limbs inhibited myogenic differentiation in a dose-dependent way as indicated by the repression of: (a) myotube formation, (b) myosin heavy chain protein accumulation, (c) myosin light chain (MLC) 1/3, alpha sk-actin and myogenic factor transcript expression. Expression of retinoic acid receptors (RAR) was also affected by RA treatment, specifically RAR gamma transcripts were induced. To further understand the pleiotropic action of RA on myogenesis, we took advantage of two muscle-specific transgene markers which consisted of CAT reporter genes driven by regulatory elements either from the myosin light chain 1/3 locus (MLC-CAT) or the alpha-skeletal actin gene (alpha sk actin-CAT). RA inhibited MLC-CAT transgene but not alpha sk actin-CAT transgene expression in primary cultures from these mice. Analysis of MLC-CAT expression in transgenic mouse primary cultures and in stably transfected C2C12 cells demonstrated that repression of MLC-CAT activity by RA was dependent upon diffusible factors in chick embryo extract. We hypothesize that during development, the pleiotropic effects of RA on myogenesis do not depend solely on the distribution and concentration of RA itself, but are also influenced by extracellular signals in the embryonic environment.

In vitro and ex vivo activities of antimicrobial agents used in combination with clarithromycin, with or without amikacin, against Mycobacterium avium

MICs of clarithromycin, amikacin, isoniazid, rifabutin, ciprofloxacin, sparfloxacin, ethambutol, and clofazimine were determined for six isolates of Mycobacterium avium complex (MAC) from AIDS patients both by the radiometric method and by an ex vivo model of infection in human macrophages. The median MICs in macrophages were similar or slightly lower than values found in broth, except for amikacin, which had slightly higher MICs inside the cells. Combinations of clarithromycin with other antimicrobial agents showed that clarithromycin-clofazimine and clarithromycin-rifabutin were synergistic on five of six strains while clarithromycin-amikacin and clarithromycin-isoniazid were antagonistic on one and two strains, respectively. The addition of amikacin made the combinations of clarithromycin-clofazimine and clarithromycin-ethambutol synergistic against all the MAC strains. In the macrophage model, the combination of clarithromycin-clofazimine (mean survival, 21%) and clarithromycin-rifabutin (mean survival, 29%) showed a strong reduction in viable counts compared with single drugs, while clarithromycin-amikacin was less active than single drugs alone. In general, the addition of amikacin did not improve the activity of the combinations, except for clarithromycin-isoniazid-amikacin (mean survival, 19%), which was significantly more active than either clarithromycin-isoniazid or clarithromycin-amikacin. The use of the macrophage model can suggest new combinations of antimicrobial agents with anti-MAC activity which, on the basis of their in vitro effectiveness, would probably be disregarded for assay in animal models.

Clastogenic effects of 1,3-butadiene and its metabolites 1,2-epoxybutene and 1,2,3,4-diepoxybutane in splenocytes and germ cells of rats and mice in vivo

Clastogenicity of 1,3-butadiene (BD), 1,2-epoxybutene (EB), and 1,2,3,4-diepoxybutane (DEB) was studied in splenocytes and germ cells of rats and mice by means of micronucleus assays (cytokinesis-block method for splenocytes, suspension method for germ cells). Inhalation exposure of mice to 200, 500, or 1,300 ppm BD (6 h/d; 5 days) induced significant chromosome damage in spermatocytes at the preleptotene stage. EB and DEB induced significant amounts of clastogenic damage in splenocytes and spermatocytes of rats and mice. The lowest tested effective doses for mice and rats were, respectively, 40 and 80 mg/kg for EB, and 15 and 30 mg/kg for DEB. In splenocytes, 80 mg EB/kg induced 3.6 times more MN in mice than in rats, whereas 30 mg DEB/kg induced the same amount of damage in both species. Damage in germ cells of mice was induced in early spermatocytes treated with 40 and 80 mg EB/kg, and in late spermatocytes exposed to 30 mg DEB/kg. In rats, 40 mg EB/kg induced damage in early spermatocytes, whereas 80 mg EB/kg induced chromosomal damage in early and late spermatocytes. In rats treated with DEB, clastogenic damage was induced in spermatocytes at preleptotene, zygotene, diplotene, and diakinesis stages. When the clastogenic potential of EB and DEB in splenocytes and germ cells of mice and rats was compared, DEB always showed a stronger effect than EB. Body weight, testis weight, ratio of testis weight to body weight, and ratio of Golgi to Golgi + cap phase spermatids were used as parameters for toxicity. Exposures to 500 and 1,300 ppm BD were somewhat toxic to mice. Doses of 80 mg EB/kg and 30 mg DEB/kg exhibited toxic effects in mice and rats.

The expression of placental glutathione-s-transferase (gst-pi) in human normal salivary-glands and tumors

Immunohistochemical localization of placental glutathione S-transferase (GST-pi) in normal and inflammatory salivary glands (74 cases) and tumors (71 cases) was studied. In the normal and inflamed salivary glands of all locations (including major and minor salivary glands), the ductal epithelial cells showed moderate to strong GST-pi staining, myoepithelial cells showed weak staining and the acinar cells were negative. The staining pattern of the tumor cells was similar to that of their normal counterparts. The tumor cells were generally positive with GST-pi staining except those tumor cells demonstrating acini differentiation (serous cells in acinic cell carcinoma, mucous cells in mucinous cystadenoma and mucoepidermoid carcinomas). Most of the salivary gland tumors, benign or malignant, showed a weak GST-pi staining. Only mucoepidermoid carcinomas demonstrated significantly increased GST-pi reactivity compared to other tumors (p<0.0001), which may be a reflection of both malignancy and squamous differentiation of the tumor. The marked increase in GST-pi activity in mucoepidermoid carcinomas may be useful in serological screening of recurrent and metastatic mucoepidermoid carcinomas.

Increased frequencies of micronuclei in early spermatids of rats following exposure of young primary spermatocytes to acrylamide

The 'suspension method' for detection of micronuclei in early spermatids (Golgi phase 1 + 2) of rats was used to study induction of chromosomal damage in spermatocytes exposed to single (50 and 100 mg/kg) or fractionated (4 x 50 mg/kg; 24-h intervals) doses of acrylamide. Animals were killed at different time intervals after treatment to measure induction of damage in different stages of spermatocyte development. A statistically significant enhancement of micronucleus frequencies was found after exposure of pre-leptotene spermatocytes to a single dose of 100 mg/kg (days 18 and 20 after treatment) or a fractionated dose of 4 x 50 mg/kg (day 19). In the latter case there was also a significant effect in zygotene spermatocytes that were sampled 15 days after treatment. Comparative studies indicated that the original 'suspension method' can be simplified by omitting enzyme treatments for the release of germ cells from the seminiferous tubules. In the present acrylamide study the old and new procedures gave similar results.

[Effects of fibronectin on cell attachment and migration of human tongue squamous cancer line Tca8113]

By using the cell culture technique in vitro, quantitative studies were carried out to test the effects of fibronectin (FN) on cell biological behaviour of human tongue squamous cancer line Tca8113 in terms of cell attachment to rat-tail collagen substrata supplemented with different concentration of FN or/and anti-FN serum as well as cell migrating distance from the agarose drop cultured with different media containing FN or/and anti-FN serum. The results displayed that FN could increase the density of cells attached to collagen substrata; the cell attachment was dose-dependent on FN. In addition, cell migration from the agarose drop might be induced and cell motility might be promoted by FN. Anti-FN serum could abolish or weaken the above-mentioned FN effects.

A single promoter sequence recognized by a newly identified alternate sigma factor directs expression of pathogenicity and host range determinants in Pseudomonas syringae

A conserved sequence motif associated with transcription of avr genes was identified in the promoter regions of six Pseudomonas syringae pv. syringae Pss61 hrp operons. A 34-bp fragment carrying this motif was cloned from the HrpZ promoter region and was shown to confer HrpL-dependent promoter activity. Expression of pathogenicity and host range determinants in P. syringae strains is thus directed by the apparent alternate sigma factor HrpL.

[Changes in cell spreading area and cell surface morphology of Tca8113 line affected by fibronectin]

Morphometric changes in cell spreading area and morphological alternation in cell surface of human tongue squamous cancer line Tca8113 on rat-tail collagen substrata supplemented with different concentration of FN and/or anti-FN serum were quantified and observed with cell culture technique as well as light and scanning electron microscopes. It was found that FN could increase the cell spreading area and also area of lamellar cytoplasm of Tca8113 cells on collagen substrata, and that cells grown on FN-collagen substrata tended to flatten out, stretch out more filopodia, and sink more deeply into the substrata with the FN concentration. The results indicated that FN might relate closely to certain stages in the process of tumor invasion.