A resonant sextuplet of sub-Neptunes transiting the bright star HD 110067

Planets with radii between that of the Earth and Neptune (hereafter referred to as 'sub-Neptunes') are found in close-in orbits around more than half of all Sun-like stars1,2. However, their composition, formation and evolution remain poorly understood3. The study of multiplanetary systems offers an opportunity to investigate the outcomes of planet formation and evolution while controlling for initial conditions and environment. Those in resonance (with their orbital periods related by a ratio of small integers) are particularly valuable because they imply a system architecture practically unchanged since its birth. Here we present the observations of six transiting planets around the bright nearby star HD 110067. We find that the planets follow a chain of resonant orbits. A dynamical study of the innermost planet triplet allowed the prediction and later confirmation of the orbits of the rest of the planets in the system. The six planets are found to be sub-Neptunes with radii ranging from 1.94R⊕ to 2.85R⊕. Three of the planets have measured masses, yielding low bulk densities that suggest the presence of large hydrogen-dominated atmospheres.

A nearby transiting rocky exoplanet that is suitable for atmospheric investigation

Spectroscopy of transiting exoplanets can be used to investigate their atmospheric properties and habitability. Combining radial velocity (RV) and transit data provides additional information on exoplanet physical properties. We detect a transiting rocky planet with an orbital period of 1.467 days around the nearby red dwarf star Gliese 486. The planet Gliese 486 b is 2.81 Earth masses and 1.31 Earth radii, with uncertainties of 5%, as determined from RV data and photometric light curves. The host star is at a distance of ~8.1 parsecs, has a J-band magnitude of ~7.2, and is observable from both hemispheres of Earth. On the basis of these properties and the planet's short orbital period and high equilibrium temperature, we show that this terrestrial planet is suitable for emission and transit spectroscopy.

A giant exoplanet orbiting a very-low-mass star challenges planet formation models

Surveys have shown that super-Earth and Neptune-mass exoplanets are more frequent than gas giants around low-mass stars, as predicted by the core accretion theory of planet formation. We report the discovery of a giant planet around the very-low-mass star GJ 3512, as determined by optical and near-infrared radial-velocity observations. The planet has a minimum mass of 0.46 Jupiter masses, very high for such a small host star, and an eccentric 204-day orbit. Dynamical models show that the high eccentricity is most likely due to planet-planet interactions. We use simulations to demonstrate that the GJ 3512 planetary system challenges generally accepted formation theories, and that it puts constraints on the planet accretion and migration rates. Disk instabilities may be more efficient in forming planets than previously thought.

Amino acid profiles of young adults differ by sex, body mass index and insulin resistance

BACKGROUND AND AIMS

An increase in plasma branched-chain amino acids is associated with a higher risk of developing type 2 diabetes and cardiovascular diseases. However, little is known about the basal plasma amino acid concentrations in young adults. Our aim was to determine the plasma amino acid profiles of young adults and to evaluate how these profiles were modified by sex, body mass index (BMI) and insulin resistance (IR).

METHODS AND RESULTS

We performed a transversal study with 608 Mexican young adults aged 19.9 ± 2.4 years who were applicants to the Universidad Autónoma de San Luis Potosí. The subjects underwent a physical examination and provided a clinical history and a blood sample for biochemical, hormonal and amino acid analyses. The women had higher levels of arginine, aspartate and serine and lower levels of α-aminoadipic acid, cysteine, isoleucine, leucine, methionine, proline, tryptophan, tyrosine, urea and valine than the men. The obese subjects had higher levels of alanine, aspartate, cysteine, ornithine, phenylalanine, proline and tyrosine and lower levels of glycine, ornithine and serine than the normal weight subjects. Subjects with IR (defined as HOMA > 2.5) had higher levels of arginine, alanine, aspartate, isoleucine, leucine, phenylalanine, proline, tyrosine, taurine and valine than the subjects without IR. Furthermore, we identified two main groups in the subjects with obesity and/or IR; one group was composed of amino acids that positively correlated with the clinical, biochemical and hormonal parameters, whereas the second group exhibited negative correlations.

CONCLUSION

This study demonstrates that young adults with obesity or IR have altered amino acid profiles characterized by an increase in alanine, aspartate, proline and tyrosine and a decrease in glycine.

Phospho-kinase profile of colorectal tumors guides in the selection of multi-kinase inhibitors

Protein kinases play a central role in the oncogenesis of colorectal tumors and are attractive druggable targets. Detection of activated kinases within a tumor could open avenues for drug selection and optimization of new kinase inhibitors. By using a phosphokinase arrays with human colorectal tumors we identified activated kinases, including the Epidermal Growth Factor Receptor (EGFR), components of the PI3K/mTOR pathway (AKT and S6), and STAT, among others. A pharmacological screening with kinase inhibitors against these proteins helped us to identify a new kinase inhibitor, termed EC-70124 that showed the highest anti-proliferative activity in cell lines. EC-70124 also inhibited cell migration and biochemical experiments demonstrated its effect targeting the PI3K/mTOR pathway. This drug also arrested cells at G2/M and induced apoptosis. Experiments in combination with standard chemotherapy used in the clinical setting indicated a synergistic effect. EC-70124 also reduced tumor growth in vivo and inhibited pS6 in the implanted tumors. In conclusion, by studying the kinase profile of colorectal tumors, we identified relevant activated pathways, and a new multi-kinase compound with significant antitumor properties.

Antitumor activity of the novel multi-kinase inhibitor EC-70124 in triple negative breast cancer

Disseminated triple negative breast cancer (TNBC) is an incurable disease with limited therapeutic options beyond chemotherapy. Therefore, identification of druggable vulnerabilities is an important aim. Protein kinases play a central role in cancer and particularly in TNBC. They are involved in many oncogenic functions including migration, proliferation, genetic stability or maintenance of stem-cell like properties. In this article we describe a novel multi-kinase inhibitor with antitumor activity in this cancer subtype. EC-70124 is a hybrid indolocarbazole analog obtained by combinatorial biosynthesis of Rebeccamycin and Staurosporine genes that showed antiproliferative effect and in vivo antitumoral activity. Biochemical experiments demonstrated the inhibition of the PI3K/mTOR and JAK/STAT pathways. EC-70124 mediated DNA damage leading to cell cycle arrest at the G2/M phase. Pathway analyses identified several deregulated functions including cell proliferation, migration, DNA damage, regulation of stem cell differentiation and reversion of the epithelial-mesenchymal transition (EMT) phenotype, among others. Combination studies showed a synergistic interaction of EC-70124 with docetaxel, and an enhanced activity in vivo. Furthermore, EC-70124 had a good pharmacokinetic profile. In conclusion these experiments demonstrate the antitumor activity of EC-70124 in TNBC paving the way for the future clinical development of this drug alone or in combination with chemotherapy.

Abstract P6-05-04: Expression of the Androgen Receptor in triple negative tumors and its modulation by receptor tyrosine kinases and downstream pathways

Background: Androgen receptor (AR) plays a central role in some tumor types like prostate cancer. Its expression and function in breast cancer is relatively unknown. Studies have linked tyrosine kinase (TK) receptors and their intracellular signaling pathways with AR status. In the present work we study the presence of AR in breast cancer human samples and how TKs can control its expression.

Methods: Tumor samples from patients were used to assess the expression of AR by western-blot. Membrane and intracellular kinases were evaluated using phosphoprotein arrays. Cell lines representative of all breast cancer subtypes were used to assess the expression of the AR and other signaling proteins using western-blot and phosphoprotein arrays. Proliferation studies with several kinase inhibitors were measured by MTT assays. We also interrogated publicly available gene expression microarray data sets with annotated clinical-pathological data.

Results: Across all the intrinsic subtypes of breast cancer, the expression of AR gene was found highly expressed in HER2-enriched and Luminal tumors and lowly expressed in Basal-like and/or triple-negative (TN) tumors. In TN tumors, PDGFRβ and EGFR were found highly activated, together with AKT and Erk1/2. A positive correlation was observed between activation of EGFR and PDGFRβ and the expression of AR. In vitro, AR protein expression varied across cell lines and was found more expressed in MCF7 (Luminal) and HS578T (TN), BT549 (TN), HCC70 (TN) and no expressed in HBL100 (TN) and MDA-MB231 (TN). Administration of the antiandrogen bicalutamide produced an anti-proliferative effect that was increased by association of an Erk1/2 inhibitor. Inhibition of the PI3K-mTOR pathway in BT549 and HS578T reduced the expression of AR but did not augment the action of bicalutamide. In TN tumors, AR gene and protein was found more expressed in older compared to younger patients.

Conclusions: In breast cancer, AR is expressed and is controlled by receptor TKs through the PI3K-mTOR pathway. An increased anti-proliferative effect is observed with the combination of bicalutamide and Erk1/2 inhibitors. AR expression correlates with age at diagnosis.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-05-04.

Effect of lipophilization of hydroxytyrosol on its antioxidant activity in fish oils and fish oil-in-water emulsions

The effect of lipophilization of the antioxidant efficiency of hydroxytyrosol on fish oil enriched systems was studied. Hydroxytyrosol fatty acid esters with increasing size of the alkyl chain and different lipophilicity were tested in bulk fish oils and fish oil-in-water emulsions. Results showed a significant antioxidant activity of hydroxytyrosol esters in both systems especially in emulsions. The introduction of a lipophilic chain decreased the antioxidant effectiveness of hydroxytyrosol in homogeneous systems as fish oils. In emulsion systems, the presence of a short-medium lipophilic chain (acetate, butyrate or octanoate) improved the antioxidant efficiency of hydroxytyrosol favoring the physical location of the antioxidant in the interface, but longer alkyl chain (laurate) maintained or even decreased their antioxidant activity. A maximum of antioxidant efficiency seems to appear when the chain length of the hydroxytyrosol derivative is that of eight carbons which is probably associated with a preferential location of the diorthophenolic moiety in the right geometry. These results are of high importance for the optimum design of effective antioxidants for omega 3 enriched foods, which are very susceptible to suffer oxidation and, then, rancidity.

Regulation of the resistance to TRAIL-induced apoptosis in human primary T lymphocytes: Role of NF-κB inhibition

Several combined strategies have been recently proposed to overcome the resistance to tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) showed by some tumor cells, thus improving the use of this death ligand in antitumor therapy. However, the molecular mechanisms of the tumor selective activity of TRAIL are not completely understood and hence the effects of the combined therapy on normal cells are unknown. Here, we have studied the resistance of primary T lymphocytes to TRAIL-mediated apoptosis. No significant differences were found in the expression of proteins involved in TRAIL-mediated apoptosis between resting and activated T cells. The low expression of death receptors TRAIL-R1/-R2 as well as the high levels of the antiapoptotic proteins TRAIL-R4 and cellular Fas-associated death domain-like IL-1beta-converting enzyme-inhibitory protein (c-FLIP) may explain the lack of caspase-8 activation observed upon TRAIL treatment in both cell types. We have also analyzed the effect of different sensitizing agents such as genotoxic drugs, phosphatidylinositol-3 kinase (PI3K) inhibitors, proteasome inhibitors, microtubule depolymerizing agents, histone deacetylase inhibitors (HDACi), and NF-kappaB inhibitors. Although some of them induced T cell death, only NF-kappaB inhibitors sensitized activated T cells to TRAIL-induced apoptosis, maybe through the regulation of the antiapoptotic proteins TRAIL-R4, c-FLIP(S) and members of the inhibitors of apoptosis proteins (IAP) family. These results question the safety of the combined treatments with TRAIL and NF-kappaB inhibitors against tumors.

The effect of diabetes and centrally administered insulin on anterior hypothalamic estrogen receptor alpha immunoreactivity

Diabetic rats have characteristic reproductive deficits. Peripheral and central (intra-cerebro-ventricular [ICV]) insulin restores the reproductive phenotype to control levels. In this experiment, we evaluated a possible defect in steroid feedback by evaluating hypothalamic estrogen receptor (ER) alpha availability using ERalpha immunocytochemistry. Animals were ovariectomised and given estradiol and progesterone. Diabetic and control animals were given ICV insulin or saline. Nuclear and/or cytoplasmic ERalpha immunoreactivity was evaluated in the paraventricular nucleus (PVN) and the organum vasculosum laminae terminalis (OVLT). In the PVN, nuclear immunoreactivity was increased among diabetic, ICV insulin-treated animals. Diabetic saline-treated and nondiabetic animals had similar ERalpha immunoreactivity. The OVLT had lower numbers of immunoreactive neurons compared to the PVN; no differences among the treatment groups were found in the OVLT. Central insulin treatment increased the number of PVN nuclear ERalpha immunoreactive neurons among diabetic animals. However, there was no reduction in ERalpha when comparing saline-treated diabetic animals to non-diabetic rats, suggesting that decreases in hypothalamic ERalpha in the regions studied do not account for diabetes-induced reproductive deficits.

Properties of triple helices formed by oligonucleotides containing 8-aminopurines

The synthesis of parallel hairpins carrying 8-aminopurines is described. These hairpins have a high affinity for specific polypyrimidine sequences resulting in the formation of very stable triplexes.

Somatosensory stimuli evoke norepinephrine release in the anterior ventromedial hypothalamus of sexually receptive female rats

We used in vivo brain microdialysis to determine the role of specific copulatory stimuli in mating-induced release of norepinephrine in the lateral ventromedial hypothalamus (VMH) of hormone-treated, sexually receptive female rats. Ovariectomized rats implanted with a unilateral guide cannula aimed at the ventrolateral VMH received systemic injections of estradiol benzoate daily for 2 days before and progesterone 4 h before the initiation of a 1-h behavioural test. Dialysis probes were lowered immediately after progesterone administration, and 20-min dialysis samples were collected until 1 h after the termination of behavioural testing. Norepinephrine content of dialysates was quantified by high performance liquid chromatography with electrochemical detection. During mating tests with male rats, dialysate levels of norepinephrine increased significantly over baseline in sexually receptive females with probe placements in the anterior but not posterior VMH. Norepinephrine levels were unchanged if rats were nonreceptive, even if males mounted vigorously and probes were located in the anterior VMH. Hormone-treated females that were placed on male-soiled bedding for 1 h showed no changes in dialysate levels of norepinephrine. Similarly, females in which vaginocervical stimulation was prevented by a vaginal mask failed to show increased levels of norepinephrine in dialysates collected from the anterior VMH, even if they displayed high levels of lordosis behaviour. Thus, the release of norepinephrine is not a result of executing the lordosis posture. The findings suggest that mating-induced increases in norepinephrine release in hormone-treated, sexually receptive rats are confined to the anterior VMH and that somatosensory rather than chemosensory stimuli evoke norepinephrine release. Moreover, experiments with vaginal masks indicate that vaginocervical stimulation is necessary for mating-evoked norepinephrine release in the anterior VMH.

Parallel-stranded hairpins containing 8-aminopurines. Novel efficient probes for triple-helix formation

We describe novel oligomers with a greater propensity to form triplexes than oligomers containing only natural bases. They consist of a polypyrimidine sequence linked head-to-head with a polypurine sequence carrying one or several 8-aminoadenine or 8-aminoguanines. The presence of 8-aminopurines also stabilised the parallel-stranded duplex structure.

Significance of nucleobase shape complementarity and hydrogen bonding in the formation and stability of the closed polymerase-DNA complex

DNA polymerases insert a dNTP by a multistep mechanism that involves a conformational rearrangement from an open to a closed ternary complex, a process that positions the incoming dNTP in the proper orientation for phosphodiester bond formation. In this work, the importance and relative contribution of hydrogen-bonding interactions and the geometric shape of the base pair that forms during this process were studied using Escherichia coli DNA polymerase I (Klenow fragment, 3'-exonuclease deficient) and natural dNTPs or non-hydrogen-bonding dNTP analogues. Both the geometric fit of the incoming nucleotide and its ability to form Watson-Crick hydrogen bonds with the template were found to contribute to the stability of the closed ternary complex. Although the formation of a closed complex in the presence of a non-hydrogen-bonding nucleotide analogue could be detected by limited proteolysis analysis, a comparison of the stabilities of the ternary complexes indicated that hydrogen-bonding interactions between the incoming dNTP and the template increase the stability of the complex by 6-20-fold. Any deviation from the Watson-Crick base pair geometry was shown to have a destabilizing effect on the closed complex. This degree of destabilization varied from 3- to 730-fold and was found to be correlated with the size of the mismatched base pair. Finally, a stable closed complex is not formed in the presence of a ddNTP or rNTP. These results are discussed in relation to the steric exclusion model for the nucleotide insertion.

Negative cell cycle regulation and DNA damage-inducible phosphorylation of the BRCT protein 53BP1

In a screen designed to discover suppressors of mitotic catastrophe, we identified the Xenopus ortholog of 53BP1 (X53BP1), a BRCT protein previously identified in humans through its ability to bind the p53 tumor suppressor. X53BP1 transcripts are highly expressed in ovaries, and the protein interacts with Xp53 throughout the cell cycle in embryonic extracts. However, no interaction between X53BP1 and Xp53 can be detected in somatic cells, suggesting that the association between the two proteins may be developmentally regulated. X53BP1 is modified via phosphorylation in a DNA damage-dependent manner that correlates with the dispersal of X53BP1 into multiple foci throughout the nucleus in somatic cells. Thus, X53BP1 can be classified as a novel participant in the DNA damage response pathway. We demonstrate that X53BP1 and its human ortholog can serve as good substrates in vitro as well as in vivo for the ATM kinase. Collectively, our results reveal that 53BP1 plays an important role in the checkpoint response to DNA damage, possibly in collaboration with ATM.

Comparison of Y chromosome and mtDNA phylogenies leads to unique inferences of macaque evolutionary history

We report here the results of one of the first analyses to use male-specific nuclear markers in elucidating primate phylogenetic relationships at the intrageneric level. Two closely linked Y chromosome markers, TSPY and SRY, were sequenced for a total of 3100 bases. Forty-four macaques, representing 18 of the 19 recognized species, were sequenced for the full 3.1 kb, as was 1 individual from each of the following outgroup genera: Papio, Theropithecus, Mandrillus, Allenopithecus,Cercopithecus, Trachypithecus, Presbytis, and Homo. In contrast to recent mtDNA phylogenies, Y chromosome loci support four monophyletic species groups, including a sinica group containing M. arctoides-a classification largely congruent with those of Fooden and Delson. Comparison of mtDNA and Y chromosome phylogenies highlight (1) a potential hybrid origin of Macaca arctoides from M. fascicularis and proto-M. assamensis/thibetana and (2) cases of mitochondrial paraphyly in macaque species whose Y chromosome lineages are monophyletic-a probable evolutionary consequence of philopatric females vs dispersing males. These results raise the question of whether a phylogenetic tree should be a topology of species origins or a depiction of more current species relationships, including subsequent episodes of introgression.

Functional hydrogen-bonding map of the minor groove binding tracks of six DNA polymerases

Recent studies have identified amino acid side chains forming several hydrogen bonds in the DNA minor groove as potentially important in polymerase replication of DNA. Few studies have probed these interactions on the DNA itself. Using non-hydrogen-bonding nucleoside isosteres, we have now studied effects in both primer and template strands with several polymerases to investigate the general importance of these interactions. All six polymerases show differences in the H-bonding effects in the minor groove. Two broad classes of activity are seen, with a first group of DNA polymerases (KF(-), Taq, and HIV-RT) that efficiently extends nonpolar base pairs containing nucleoside Q (9-methyl-1H-imidazo[4,5-b]pyridine) but not the analogue Z (4-methylbenzimidazole), implicating a specific minor groove interaction at the first extension site. A second group of polymerases (Pol alpha, Pol beta, and T7(-)) fails to extend all non-H-bonding base pairs, indicating that these enzymes may need minor groove hydrogen bonds at both minor groove sites or that they are especially sensitive to noncanonical DNA structure or stability. All DNA polymerases examined use energetically important minor groove interactions to probe newly synthesized base pairs before extending them. The positions of these interactions vary among the enzymes, and only a subset of the interactions identified structurally appears to be functionally important. In addition, polymerases appear to be differently sensitive to small changes in base pair geometry.

Importance of terminal base pair hydrogen-bonding in 3'-end proofreading by the Klenow fragment of DNA polymerase I

We describe studies aimed at evaluating the physical factors governing the rate of 3'-end proofreading by the Klenow fragment of E. coli DNA polymerase I. Two nonpolar deoxynucleoside isosteres containing 2,4-difluorotoluene (F) and 4-methylbenzimidazole (Z), which are non-hydrogen-bonding shape mimics of thymine and adenine, respectively, are used to investigate the effects of base pair geometry and stability on the rate of this exonuclease activity. Steady-state kinetics measurements show that complementary T.A base pairs at the end of a primer-template duplex are edited 14-40-fold more slowly than mismatches. By contrast, a 3'-end T residue in a T. Z pair is edited at a rate equivalent to that of natural base mismatches despite the fact that it resembles a T.A pair in structure. Similarly, the A in an A.F pair is edited as rapidly as a mismatched pair despite its close structural mimicry of an A.T pair. Interestingly, when the base pairs are reversed and F or Z is located at the 3'-end, they are edited more slowly, possibly implicating specific interactions between the exonuclease domain and the base of the nucleotide being edited. Finally, thermal denaturation studies are carried out to investigate the relationship between editing and the ease of unwinding of the duplex. The rapid editing of bases opposite F or Z residues at the duplex terminus seems to correlate well with the stability of these base pairs when placed in a context resembling a primer-template duplex. In general, the rate of 3'-end editing appears to be governed by the rate of fraying of the DNA terminal pair, and base pair geometry appears to have little effect.

Mimicking the Structure and Function of DNA: Insights into DNA Stability and Replication

The physical and chemical factors that allow DNA to perform its functions in the cell have been studied for several decades. Recent advances in the synthesis and manipulation of DNA have allowed this field to move ahead especially rapidly during the past fifteen years. One of the most common chemical approaches to the study of interactions involving DNA has been the use of DNA base analogues in which functional groups are added, deleted, blocked, or rearranged. Here we describe a different strategy, in which the polar natural DNA bases are replaced by nonpolar aromatic molecules of the same size and shape. This allows the evaluation of polar interactions (such as hydrogen bonding) with little or no interference from steric effects. We have used these nonpolar nucleoside isosteres as probes of noncovalent interactions such as DNA base pairing and protein - DNA recognition. We have found that, while base-pairing selectivity does depend on Watson - Crick hydrogen bonding in the natural pairs, it is possible to design new bases that pair selectively and stably in the absence of hydrogen bonds. In addition, studies have been carried out with DNA polymerase enzymes to investigate the importance of Watson - Crick hydrogen bonding in enzymatic DNA replication. Surprisingly, this hydrogen bonding is not necessary for efficient enzymatic synthesis of a base pair, and significant levels of selectivity can arise from steric effects alone. These results may have significant impact both on the study of basic biomolecular interactions and in the design of new, functionally active biomolecules.

The long and short of it: branch lengths and the problem of placing the New Zealand short-tailed bat, Mystacina

The taxonomic position of the endemic New Zealand bat genus Mystacina has vexed systematists ever since its erection in 1843. Over the years the genus has been linked with many microchiropteran families and superfamilies. Most recent classifications place it in the Vespertilionoidea, although some immunological evidence links it with the Noctilionoidea (=Phyllostomoidea). We have sequenced 402 bp of the mitochondrial cytochrome b gene for M. tuberculata (Gray in Dieffenbach, 1843), and using both our own and published DNA sequences for taxa in both superfamilies, we applied different tree reconstruction methods to find the appropriate phylogeny and different methods of estimating confidence in the parts of the tree. All methods strongly support the classification of Mystacina in the Noctilionoidea. Spectral analysis suggests that parsimony analysis may be misleading for Mystacina's precise placement within the Noctilionoidea because of its long terminal branch. Analyses not susceptible to long-branch attraction suggest that the Mystacinidae is a sister family to the Phyllostomidae. Dating the divergence times between the different taxa suggests that the extant chiropteran families radiated around and shortly after the Cretaceous-Tertiary boundary. We discuss the biogeographical implications of classifying Mystacina within the Noctilionoidea and contrast our result with those classifications placing Mystacina in the Vespertilionoidea, concluding that evidence for the latter is weak.

[Composition of chicken and quail eggs]

Qualified food composition data on lipids composition are needed to evaluate intakes as a risk factor in the development of heart disease. Proximal composition, cholesterol and fatty acid content of chicken and quail eggs, usually consumed or traded, were analysed. Proximal composition were determined using AOAC (1984) specific techniques; lipids were extracted by a Folch's modified technique and cholesterol and fatty acids were determined by gas chromatography. Results corroborate the stability of eggs composition. Cholesterol content of quail eggs is similar to chicken eggs, but it is almost the half content of data registered in Handbook 8. Differences may be attributed to the analytical methodology used to obtain them. This study provides data obtained with up-date analytical techniques and accessory information useful for food composition tables.

Cyclic GMP may potentiate lordosis behaviour by progesterone receptor activation

The purpose of this study was to test the hypothesis that cGMP acts as a progesterone substitute to facilitate lordosis in oestrogen-primed rats. Female Sprague-Dawley rats underwent stereotaxic surgery to place a 26-gauge guide cannula into the third ventricle. Bilateral ovariectomy was done at the same time as stereotaxic surgery. Five days later ovariectomized rats were primed with 2 microg estradiol benzoate 24 and 48 h prior to behaviour testing. Some animals were further injected with 200 microg progesterone 4 h before behaviour testing. A nitric oxide synthase inhibitor infused into the third ventricle before progesterone administration significantly reduced lordosis performance. 8-Bromo-cGMP, a cell permeable cGMP analogue, or saline vehicle was infused into the third ventricle of hormone-primed animals approximately 4 h prior to the first of 3-h behaviour tests. This cGMP analogue facilitated lordosis behaviour. We next used KT5823, a highly specific inhibitor of protein kinase G (PKG), to test the hypothesis that cGMP action is mediated by this kinase. In this experiment, KT5823 was infused 15 min before progesterone. KT5823 significantly decreased lordosis behaviour. RU486, a progesterone receptor antagonist, was used to assess whether the stimulatory effects of cGMP are mediated through the progesterone receptor. Oestrogen-primed animals were injected with 5 mg of RU486 or vehicle 60 min before infusion with 8-bromo-cGMP. RU486 significantly attenuated cGMP-facilitated lordosis behaviour. These data show that cGMP facilitates lordosis through activation of PKG and the progesterone receptor.

Intracerebroventricular leptin regulates hepatic but not peripheral glucose fluxes

Acute intravenous infusions of leptin markedly alter hepatic glucose fluxes (Rossetti, L., Massillon, D., Barzilai, N., Vuguin, P., Chen, W., Hawkins, M., Wu, J., and Wang, J. (1997) J. Biol. Chem. 272, 27758-22763). Here we examine whether intracerebroventricular (ICV) leptin administration regulates peripheral and hepatic insulin action. Recombinant mouse leptin (n = 14; 0.02 or 1 microgram/kg.h) or vehicle (n = 9) were administered ICV for 6 h to conscious rats, and insulin action was determined by insulin (3 milliunits/kg.min) clamp and tracer dilution techniques. During physiologic hyperinsulinemia (approximately 65 microunits/ml), the rates of glucose uptake (Rd, 20.1 +/- 0.6 and 23.1 +/- 0.7 versus 21.7 +/- 0.6 mg/kg.min; p = NS), glycolysis and glycogen synthesis were similar in rats receiving low- and high-dose leptin versus vehicle. ICV leptin resulted in a 2-3-fold increase in hepatic phosphoenolpyruvate carboxykinase mRNA levels. Glycogenolysis and PEP-gluconeogenesis (2.1 +/- 0.3 mg/kg. min) contributed similarly to endogenous glucose production (GP) in the vehicle-infused group. However, gluconeogenesis accounted for approximately 80% of GP in both groups receiving ICV leptin, while hepatic glycogenolysis was markedly suppressed (0.7 +/- 0.3 and 1.2 +/- 0.3 versus 2.2 +/- 0.4 mg/kg.min, in rats receiving low- and high-dose leptin versus vehicle, respectively; p < 0.01). In summary, short-term ICV leptin administration: 1) failed to affect peripheral insulin action, but 2) induced a striking re-distribution of intrahepatic glucose fluxes. The latter effect largely reproduced that of leptin given systemically at much higher doses. Thus, the regulation of hepatic glucose fluxes by leptin is largely mediated via its central receptors.

Efficient replication between non-hydrogen-bonded nucleoside shape analogs

DNA polymerase enzymes make an error only once per 10(4)-10(5) initial nucleotide insertions during DNA replication. Most currently held models of this high fidelity cite the hydrogen bonds between complementary pyrimidines and purines as a critical controlling factor. Testing this has been difficult, however, since standard molecular strategies for blocking or removing polar hydrogen-bonding groups cause changes to size and shape as well as hydrogen bonding ability. One answer to this problem is the use of nonpolar molecules that mimic the shape of natural DNA bases. Here we show that a non-hydrogen-bonding shape mimic for adenine is replicated efficiently and selectively against a nonpolar shape mimic for thymine. The results establish that hydrogen bonds in a base pair are not absolutely required for efficient nucleotide insertion. This adds support to the idea that shape complementarity may play as important a role in replication as base-base hydrogen bonds.

Effects of diabetes and estradiol on norepinephrine release in female rat hypothalamus, preoptic area and cortex

These studies determined whether diabetes and estradiol treatment altered norepinephrine (NE) release from hypothalamus, preoptic area (POA), and cortical slices from ovariectomized (OVX) female rats. Animals were sacrificed 12 days after the onset of streptozotocin-induced diabetes and 48 h following vehicle or estradiol injection. Brain slices were preloaded with 3H-NE, and release was evoked twice (S and S2) by electrical stimulation. Diabetes increased hypothalamic NE release during S1 regardless of the administration of vehicle or estradiol. Neither estradiol treatment nor diabetes alone affected NE release during S2 in the hypothalamus or POA. Estradiol treatment elevated NE release in the POA during S2 but only in diabetic animals. Moreover, estradiol elevated cortical NE release during S2 regardless of the presence or absence of disease. We also examined whether alpha2-adrenoceptor regulation of NE release was influenced by diabetes or hormone treatment. Enhancement of NE release by alpha2-adrenoceptor antagonism was evident in all 3 brain regions. However, alpha2-adrenoceptor regulation of NE release was unaffected by diabetes and hormone treatment. These findings suggest that diabetes alters NE release in the hypothalamus/POA of female rats. Additionally, this work identifies a novel action of estradiol to enhance stimulated NE release in the cortex of female rats.

Phylogenetic relationships of the macaques (Cercopithecidae: Macaca), as revealed by high resolution restriction site mapping of mitochondrial ribosomal genes

Molecular phylogenetic relationships among all recognized species within the genus Macaca, were assessed using high-resolution restriction site mapping of the mitochondrial ribosomal genes. By outgroup comparisons to other members of the cercopithecine subfamily, the macaques appear to be a monophyletic assemblage. Within the genus, the relationships are in general consistent with previous genetic studies, though they are less concordant with the separation of the species into four distinct species groups based on modification of the genitalia. Our data support: (1) Macaca sylvanus as sister clade to all Asian macaques; (2) the silenus group as a monophyletic assemblage, with the Sulawesi macaques diverging and colonizing Sulawesi much earlier than previously thought; (3) the fascicularis group as a paraphyletic assemblage, including all non-silenus group Asian macaques; (4) the sinica group as a monophyletic assemblage, possibly derived from a fascicularis-like ancestor; and (5) Macaca arctoides as a separate lineage from the sinica group, also originating from a fascicularis-like ancestor. This study supports the notion that species with more specialized genitalia evolved from less derived taxa, and in general are in agreement with the dispersal scenarios proposed by Fooden (1980) and Delson (1980) for the macaques.

Fulminant amebic colitis: analysis of 55 cases

Fulminant amebic colitis is a rare disease with high morbidity and mortality.

PURPOSE

This study was designed to identify the most frequent clinical and histopathologic features of fulminant amebic colitis and to analyze results of surgical treatment and the existence of risk factors for mortality.

MATERIALS AND METHODS

A retrospective analysis was conducted of clinical and histopathologic data of 55 patients with fulminant amebic colitis. Data were obtained from the files of autopsies and surgical operations that had been performed at a referral center in Mexico from 1943 through 1994.

RESULTS

Median age was 52 (range, 18-79) years. There were 34 men (62 percent) and 21 women (38 percent). Diabetes mellitus and chronic alcoholism were the most frequent diseases in association with fulminant amebic colitis (40 and 31 percent, respectively). The most frequent clinical manifestations were abdominal pain, diarrhea, rectal bleeding, and fever. There was a coexistent amebic liver abscess in 54 percent of patients. The main histopathologic characteristics were necrosis, presence of trophozoites, and acute and/or chronic inflammation. Of 25 patients who underwent surgery, only six survived (operative mortality, 76 percent; overall mortality, 89 percent). The variables that correlated with mortality were longer duration of symptoms, lower count of leukocytes, nonsurgical treatment, nonresective surgical procedure, hospital admission before 1971, and invasion of trophozoites into or through the muscularis.

CONCLUSIONS

The results may help to obtain an earlier diagnosis and establish proper treatment of fulminant amebic colitis.

Deficits in reproductive behavior in diabetic female rats are due to hypoinsulinemia rather than hyperglycemia

These studies determined whether deficits in reproductive behavior observed in streptozotocin (STZ)-induced diabetic female rats are caused by hyperglycemia or loss of insulin. Female Sprague-Dawley rats were ovariectomized and made diabetic by a single ip injection of STZ (75 mg/kg). Reproductive behavior was measured 12 days after the onset of hyperglycemia following the injection of estrogen and progesterone in doses known to restore reproductive behavior in nondiabetic rats. Rats in which STZ produced diabetes showed significantly reduced receptive and proceptive sexual behaviors. Normalization of blood glucose levels either by restricting diet or by phlorizin treatment failed to restore reproductive behavior in diabetic animals. However, even doses of insulin which were not fully effective in correcting peripheral hyperglycemia were able to prevent the STZ-induced behavioral deficit. No changes in general activity were observed in any experimental group as assessed by open field activity. The density of the norepinephrine transporter, as measured by [3H]nisoxetine binding, was reduced in the cortex but not in the brain stem, hypothalamus, or hippocampus of diabetic animals. Insulin treatment prevented the loss of cortical [3H]nisoxetine binding, and even partial normalization of blood glucose restored cortical [3H]nisoxetine binding to control levels. These findings suggest that diabetes-induced reproductive deficits are due to hypoinsulinemia and cannot be corrected simply by the normalization of blood glucose, whereas reductions in the density of cortical norepinephrine transporter result from hyperglycemia.

Comparative molecular phylogeography of two Xenopus species, X. gilli and X. laevis, in the south-western Cape Province, South Africa

Xenopus gilli is a vulnerable anuran with a patchy distribution along the south-western coast of the Cape Province, South Africa. This species is sympatric with Xenopus laevis laevis, a widespread relative found over much of southern Africa. We examined the molecular phylogeography and population structure of the contact zone between these species to obtain information about historical biogeography and conservation management of this region. Analyses of the distribution, frequency, and cladistic and phenetic relationships among mitochondrial DNA haplotypes indicate that population subdivision is present in both taxa but that long-term isolation of sets of populations has occurred in X. gilli only. Haplotype and nucleotide diversity are also considerably higher within and among X. gilli ponds than X. l. laevis ponds in this region. We attribute the genetic segregation of X. gilli populations to ancient habitat fragmentation by ocean transgression into X. gilli habitat and to continued habitat alteration by human activity. The lower level of genetic diversity in X. L. laevis in this region is likely a result of a recent arrival of this taxon to the south-western Cape region relative to X. gilli. Population structure in X. l. laevis may be a result of isolation by distance. Clear evidence exists for at least two management units within X. gilli and strongly supports the establishment of protective measures east of False Bay in order to conserve a substantial portion of this species' extant genetic diversity.

Molecular systematics of the living rhinoceros

Classification of the living species of rhinoceros has been somewhat controversial. Traditionally, the two-horned rhinoceros, which includes the African (Diceros and Ceratotherium) and the Asian (Dicerorhinus) forms, has been included in one group separate from the one-horned rhinoceros (Rhinoceros). However, recently some authors have regarded the Asian species as a group separate from the African species, irrespective of the number of horns. Furthermore, others have split the living rhinoceros into three unrelated groups that include the African two-horned species in one group, the Asian two-horned rhinoceros in another group, and the Asian one-horned rhinoceros in a third group. We investigated the systematic relationships of the living rhinoceros using high-resolution restriction site mapping of the ribosomal genes of the mitochondrial DNA, and our results support the traditional subdivision of the living rhinoceros based on the number of horns. Few groups of mammals are more critically endangered than the rhinoceros, and the data obtained in this work should provide information relevant to their conservation.

Partial endonuclease digestion mapping of restriction sites using PCR-amplified DNA

Although direct DNA sequencing is now readily available, restriction enzyme analyses are still widely used in population genetics and molecular systematics studies. These analyses provide cheaper and faster ways to assay patterns of nucleotide differentiation across a large number of individuals. In this paper, we introduce a new approach to restriction enzyme analyses in which high-resolution restriction site maps are obtained from partial digestions of PCR products. This procedure increases the level of resolution at least an order of magnitude over the double-digestion method for restriction enzyme mapping, can target specific DNA regions with the use of specific primers, and, because it uses chemiluminescent detection of DNA, can be easily implemented in laboratories that lack the necessary setups to handle radioactive substances.

[Chronic diseases in childhood: an approximate measurement of their impact]

As an approach to measurement of the importance of chronic diseases in childhood, type and frequency of diagnoses in children admitted to the pediatric wards of a general metropolitan hospital at Santiago, Chile, were reviewed and recorded along hospitalization and at the time of discharge from March 1 through June 30, 1989 (n: 426). Newborns were excluded. Main problems of the study were lacks of uniform national criteria to define chronic illness and of modern technology to certify diagnoses. Ninety five hospital discharged children (23.3%) were considered to have a definitive, confirmed chronic disease (CCD), other 51 (12%) were cases of possibly chronic disease (PCD) while the remainder were thought to be carriers of acute illness. Among 146 patients taken as CCD or PCD cases, 126 (87.7%) were considered to have single organic system diseases as defined by areas of medical interest or specialty; other 3 cases (8.9%) had two affected systems and 5 children (3.4%) had three or more involved systems. More frequently affected systems (in number of cases) and their corresponding proportions of CCD were as follows: neurologic (31 cases and 58.1% CCD), oncohematologic (28 cases and 96.4% CCD) and gastrointestinal (26 cases and 26.9% CCD). More extensive studies, covering other medical care providing settings are desirable and necessary to measure the magnitude and features of chronic disease entities in chilean childhood.

[Action of vasoactive drugs in male sexual impotence]

Intracavernous injection of papaverine and phentolamine (Regitine) was performed in 223 impotent men. These patients had been previously evaluated at another department. Patient failure to obtain spontaneous erection during sleep or on waking was a prerequisite for inclusion in the study. Following evaluation of the penile brachial pressure index (PBI), patients under 50 years received an intracavernous injection of 0.5 mg. Regitine and papaverine 30 mg; patients over 50 years received 1 mg. Regitine and 30 mg. papaverine. Patients were observed for a minimum of 30 minutes. Fifty-eight attained erection and the remaining patients achieved varying degrees of penile tumescence. Patients were advised to have sexual intercourse within two hours following injection. Fifty-eight patients attained erection immediately and 132 achieved erection following immediate sexual stimulation. Of these 132 patients, 72 (54.5%) had successful sexual intercourse, 60 (45.5%) failed to obtain erection sufficient for coitus. We are unaware of the result in the remaining 33 patients who had none or late sexual stimulation. Of the 58 patients who achieved erection, the PBI could be quantified in 53 (mean 0.84). Likewise, the PBI could be determined in the 141 patients who had failed to achieve erection immediately (mean 0.77). Priapism was the only serious complication observed. Seven (3.1%) patients who presented with this condition were treated with the intracavernous injection of dopamine.