Correlated translational motions in pseudo-rotaxane complexes controlled by a single chemical stimulus

Coordinated motions are essential in the operation of molecular machines. This feature can be achieved by landscaping the energy surface along the movement coordinates. Herein, we present an approach of using a single stimulus to modify the free energy curve describing the threading and shuttling of a ring along a linear molecule. This approach has been realized by locating two identical ring-binding sites near the axle termini.

Expression of mTOR in normal and pathological conditions

The mechanistic/mammalian target of rapamycin (mTOR), a protein discovered in 1991, integrates a complex pathway with a key role in maintaining cellular homeostasis. By comprising two functionally distinct complexes, mTOR complex 1 (mTORC1) and mTORC2, it is a central cellular hub that integrates intra- and extracellular signals of energy, nutrient, and hormone availability, modulating the molecular responses to acquire a homeostatic state through the regulation of anabolic and catabolic processes. Accordingly, dysregulation of mTOR pathway has been implicated in a variety of human diseases. While major advances have been made regarding the regulators and effectors of mTOR signaling pathway, insights into the regulation of mTOR gene expression are beginning to emerge. Here, we present the current available data regarding the mTOR expression regulation at the level of transcription, translation and mRNA stability and systematize the current knowledge about the fluctuations of mTOR expression observed in several diseases, both cancerous and non-cancerous. In addition, we discuss whether mTOR expression changes can be used as a biomarker for diagnosis, disease progression, prognosis and/or response to therapeutics. We believe that our study will contribute for the implementation of new disease biomarkers based on mTOR as it gives an exhaustive perspective about the regulation of mTOR gene expression in both normal and pathological conditions.

Search for 70 μeV Dark Photon Dark Matter with a Dielectrically Loaded Multiwavelength Microwave Cavity

Microwave cavities have been deployed to search for bosonic dark matter candidates with masses of a few μeV. However, the sensitivity of these cavity detectors is limited by their volume, and the traditionally employed half-wavelength cavities suffer from a significant volume reduction at higher masses. Axion dark matter experiment (ADMX)-Orpheus mitigates this issue by operating a tunable, dielectrically loaded cavity at a higher-order mode, which allows the detection volume to remain large. The ADMX-Orpheus inaugural run excludes dark photon dark matter with kinetic mixing angle χ>10^{-13} between 65.5  μeV (15.8  GHz) and 69.3  μeV (16.8  GHz), marking the highest-frequency tunable microwave cavity dark matter search to date.

An Operative Electrostatic Slipping Mechanism along Macrocycle Flexibility Accelerates Guest Sliding during pseudo-Rotaxane Formation

A pseudo‐rotaxane is a host−guest complex composed of a linear molecule encircled by a macrocyclic ring. These complexes can be assembled by sliding the host over the guest terminal groups. If there is a close match between the molecular volume of the flanking groups on the guest and the cavity size of the macrocycle, the slipping might occur slowly or even become completely hindered. We have previously shown that it is possible to overcome the restraints imposed by steric effects on the sliding process by integrating electrostatic attractive interactions during the slipping step. In this work, we extend our electrostatically assisted slipping approach (EASA) to a new host−guest system featuring a flexible macrocyclic ring and a series of asymmetric guests containing a cyclic tertiary ammonium group. Compelling evidence for pseudo‐rotaxane formation is presented, along with thermodynamic and kinetic data. Experimental results suggests that the higher conformational flexibility of 24‐crown‐8 significantly increases the sliding rate, compared with the more rigid dibenzo‐24‐crown‐8, without affecting complex stability. Furthermore, by combining the EASA and macrocycle flexibility, we were capable to slip a large eight‐membered cyclic group across the 24‐crown‐8 annulus, setting a new limit on the ring molecular size that can pass through a 24‐membered crown ether.

Search for Invisible Axion Dark Matter in the 3.3-4.2 μeV Mass Range

We report the results from a haloscope search for axion dark matter in the 3.3-4.2  μeV mass range. This search excludes the axion-photon coupling predicted by one of the benchmark models of "invisible" axion dark matter, the Kim-Shifman-Vainshtein-Zakharov model. This sensitivity is achieved using a large-volume cavity, a superconducting magnet, an ultra low noise Josephson parametric amplifier, and sub-Kelvin temperatures. The validity of our detection procedure is ensured by injecting and detecting blind synthetic axion signals.

Axion Dark Matter Experiment: Detailed design and operations

Axion dark matter experiment ultra-low noise haloscope technology has enabled the successful completion of two science runs (1A and 1B) that looked for dark matter axions in the 2.66-3.1 μeV mass range with Dine-Fischler-Srednicki-Zhitnisky sensitivity [Du et al., Phys. Rev. Lett. 120, 151301 (2018) and Braine et al., Phys. Rev. Lett. 124, 101303 (2020)]. Therefore, it is the most sensitive axion search experiment to date in this mass range. We discuss the technological advances made in the last several years to achieve this sensitivity, which includes the implementation of components, such as the state-of-the-art quantum-noise-limited amplifiers and a dilution refrigerator. Furthermore, we demonstrate the use of a frequency tunable microstrip superconducting quantum interference device amplifier in run 1A, and a Josephson parametric amplifier in run 1B, along with novel analysis tools that characterize the system noise temperature.

Probing Gluon Spin-Momentum Correlations in Transversely Polarized Protons through Midrapidity Isolated Direct Photons in p^{↑}+p Collisions at sqrt[s]=200 GeV

Studying spin-momentum correlations in hadronic collisions offers a glimpse into a three-dimensional picture of proton structure. The transverse single-spin asymmetry for midrapidity isolated direct photons in p^{↑}+p collisions at sqrt[s]=200  GeV is measured with the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). Because direct photons in particular are produced from the hard scattering and do not interact via the strong force, this measurement is a clean probe of initial-state spin-momentum correlations inside the proton and is in particular sensitive to gluon interference effects within the proton. This is the first time direct photons have been used as a probe of spin-momentum correlations at RHIC. The uncertainties on the results are a 50-fold improvement with respect to those of the one prior measurement for the same observable, from the Fermilab E704 experiment. These results constrain gluon spin-momentum correlations in transversely polarized protons.

Extended Search for the Invisible Axion with the Axion Dark Matter Experiment

This Letter reports on a cavity haloscope search for dark matter axions in the Galactic halo in the mass range 2.81-3.31  μeV. This search utilizes the combination of a low-noise Josephson parametric amplifier and a large-cavity haloscope to achieve unprecedented sensitivity across this mass range. This search excludes the full range of axion-photon coupling values predicted in benchmark models of the invisible axion that solve the strong CP problem of quantum chromodynamics.

An Anionic Ring Locked into an Anionic Axle: A Metastable Rotaxane with Chemically Activated Electrostatic Stoppers

The use of the electrostatic stoppers concept in the field of mechanically interlocked molecules is reported; these stoppers are chemically sensitive end groups on a linear guest molecule that allows for the conversion of a pseudo-rotaxane species into a rotaxane complex by a change in the medium acidity. The chemical stimulus causes the appearance of negative charges on both ends of the linear component, passing from cationic to anionic, and causing a significant ring-to-axle electrostatic repulsion. This phenomenon has two different and simultaneous effects: 1) destabilizes the complex as a consequence of confining an anionic ring into an anionic axle, and 2) increases the dissociation energy barrier, thus impeding ring extrusion. This newly formed metastable rotaxane species is resistant to solvent and temperature effects and performs as a two-state degenerated molecular shuttle in solution.

Nuclear Dependence of the Transverse Single-Spin Asymmetry in the Production of Charged Hadrons at Forward Rapidity in Polarized p+p, p+Al, and p+Au Collisions at sqrt[s_{NN}]=200 GeV

We report on the nuclear dependence of transverse single-spin asymmetries (TSSAs) in the production of positively charged hadrons in polarized p^{↑}+p, p^{↑}+Al, and p^{↑}+Au collisions at sqrt[s_{NN}]=200  GeV. The measurements have been performed at forward rapidity (1.4<η<2.4) over the range of transverse momentum (1.8<p_{T}<7.0  GeV/c) and Feynman x (0.1<x_{F}<0.2). We observed positive asymmetries for positively charged hadrons in p^{↑}+p collisions, and significantly reduced asymmetries in p^{↑}+A collisions. These results reveal a nuclear dependence of TSSAs for charged-hadron production in a regime where perturbative techniques are applicable. These results provide new opportunities to use p^{↑}+A collisions as a tool to investigate the rich phenomena behind TSSAs in hadronic collisions and to use TSSAs as a new handle in studying small-system collisions.

B-66 The Effect of Bilingualism on Boston Naming Test Performance in Traumatic Brain Injury Survivors and Healthy Adults

Objective

The Boston Naming Test (BNT) is a lexical-retrieval task. It has been documented that those with a history of traumatic brain injury (TBI) have reduced performance on the BNT. Bilingualism is also known to impact BNT performances. We examined the relationship of TBI and bilingualism/monolingualism on BNT performances.

Method

The sample (N = 95) consisted of 36 healthy controls (19 bilingual; 17 monolingual), 32 acute TBI participants (12 bilingual; 20 monolingual), and 27 chronic TBI participants (16 bilingual; 11 monolingual). Acute TBI participants were tested 6 months post-injury and chronic TBI participants were tested 12 months or more post-injury. All participants passed performance validity testing. A 3X2 ANOVA was conducted to determine the effect of TBI and bilingualism/monolingualism on BNT performance.

Results

A main effect was found for group (i.e., control, 6 month TBI, and 12 month TBI), p < .001, ηp² = .21. Pairwise comparisons revealed that acute TBI participants performed worse than the control and chronic TBI groups. A main effect for bilingualism/ monolingualism was found, p < .001, ηp² = .14; monolinguals performed better on the BNT. No interactions were found between TBI and bilingualism/monolingualism.

Conclusions

BNT performance improves overtime in TBI and the pattern of improvement post-TBI is not statistically different between bilingual/monolingual groups. Relative to monolinguals, bilingual participants demonstrated worse BNT performance.

B-71 The Effect of Bilingualism on Verbal and Design Fluency Performance in Traumatic Brain Injury Survivors and Healthy Adults

Objective

Traumatic brain injury (TBI) impacts neurocognitive function. Language is also known to influence test performances. We examined the relationship between TBI and monolingualism/bilingualism on verbal and design fluency tests.

Method

The sample (N = 74) consisted of 33 healthy controls (18 bilingual; 15 monolingual), 15 acute TBI participants (6 bilingual; 9 monolingual), and 26 chronic TBI participants (15 bilingual; 11 monolingual). Acute TBI participants were tested 6 months post-injury and chronic TBI participants were tested 12 months or more post-injury. The Delis-Kaplan Executive Function System Letter Fluency (DKEFS-LF), Category Fluency (DKEFS-CF), Category Switching Fluency (DKEFS-CSF), and global verbal fluency composite (DKEFS-GVF) scores assessed verbal fluency; DKEFS fill-dots (DKEFS-FD), empty dots (DFEFS-ED), dot switching (DKEFS-DS), and global design fluency composite (DKEFS-GDF) scores assessed design fluency; and global verbal and non-verbal fluency composite (DKEFS-GF) assessed overall fluency. 3X2 ANOVAs were conducted to evaluate the effect of monolingualism/bilingualism on fluency performance in TBI and controls.

Results

The groups (control and TBI groups) differed for DKEFS-LF, p = .048, ηp² = .09, DKEFS-CF, p = .000, ηp² = .21, DKEFS-GVF, p = .004, ηp² = .15, DKEFS-ED, p = .008, ηp² = .13, DKEFS-GF, p = .001, ηp² = .20, with controls outperforming TBI groups on the DKEFS-CF, DKEFS-GVF, and DKEFS-GF. Furthermore, controls outperformed acute TBI participants on the DKEFS-LF and DKEFS-ED. Main effects were found for bilingualism/monolingualism on DKEFS-CF, p = .035, ηp² = .06, with bilinguals outperforming monolinguals. No interactions were found.

Conclusion

The TBI group had poor verbal and design fluency in contrast controls. Unexpectedly, bilinguals outperformed monolinguals on a task of verbal category fluency. Revealing that in the present study bilinguals have better semantic verbal fluency abilities.

A-01 Age of Immigration and Test Performance for Immigrant Spanish-speakers on Córdoba Naming Test

Objective

This study examines the correlation between age of immigration for Spanish speakers in the USA and their performance on the Córdoba Naming Test (CNT), a confrontation naming test designed to be multicultural. We predicted that those who immigrated at a later age, whom we expect to have more years of education in their native language, will perform better on the CNT.

Method

The study used the CNT with a sample of 44 Spanish-speakers from the United States. We worked with participants with no prior history of medical complications, such as damage to the central nervous system, drug use, or excessive alcohol use. 21 male and 23 female participants were recruited. The age of participants ranged from 20 to 89 years old and education ranged from 0 to 22 years of schooling (either in the United States or in their native country). The variables of focus are the age of immigration into the United States (when participants migrated into the US) and their test performance on the CNT (total score of correct responses).

Results

Our results indicate a statistically significant positive correlation between age of immigration and performance on the CNT, (r(44)) = .357, p = .019). Conclusions: The overall trend of the data suggested that older age at immigration was indeed associated with better performance on the CNT, thus highlighting the importance of language and acculturation issues when being assessed with neuropsychological or cognitive testing.

Conclusions

The overall trend of the data suggested that older age at immigration was indeed associated with better performance on the CNT, thus highlighting the importance of language and acculturation issues when being assessed with neuropsychological or cognitive testing.

B-69 The Effect of Bilingualism on Symbol Digit Modalities Test Performance in Traumatic Brain Injury Survivors and Healthy Adults

Objective

Traumatic brain injury (TBI) survivors exhibit cognitive deficits. Language factors can also influence neurocognitive performance. We examined the effects of TBI and bilingualism/monolingualism on a test of attention and cognitive speed (i.e., Symbol Digit Modalities Test; SDMT).

Method

The sample (N = 98) consisted of 37 controls (19 bilingual; 18 monolingual), 34 acute TBI participants (12 bilingual; 22 monolingual), and 27 chronic TBI participants (16 bilingual; 11 monolingual). Acute TBI participants were tested 6 months post-injury; chronic TBI participants were tested 12 months or more post-injury. All participants passed performance validity testing. 3X2 ANOVAs were conducted to determine the effect of TBI and language on SDMT written and oral performance.

Results

A main effect was found between groups (control and TBI groups) on SDMT written, p < .001, ηp² = .19 and SDMT oral p < .001, ηp² = .16. Pairwise comparisons revealed a difference between the control group and TBI groups, with TBI groups performing worse. A main effect for bilingualism/monolingualism was not found; interaction effects emerged between TBI and bilingualism/monolingualism on SDMT written, p < .05, ηp² = .07 and SDMT oral p < .05, ηp² = .07.

Conclusion

TBI groups performed worse than controls on the SDMT. Relative to monolinguals with TBI, our findings suggest better cognitive recovery of verbal attention and cognitive speed in bilingual TBI participants.

B-67 The Effect of Bilingualism on Executive Functioning Performance in Traumatic Brain Injury Survivors and Healthy Adults

Objective

Traumatic brain injury (TBI) survivors often exhibit problems with executive function (EF). Language use can also impact EF test performances. We examined the effects of TBI and bilingualism/monolingualism on several EF tests.

Method

The sample (N = 94) consisted of 37 healthy controls (19 bilingual; 18 monolingual), 30 acute TBI participants (10 bilingual; 20 monolingual), and 27 chronic TBI participants (16 bilingual; 11 monolingual). Acute TBI participants were tested 6 months post-injury and chronic TBI participants were tested 12 months or more post-injury. Stroop Color-Word (SCW), Delis-Kaplan Executive Function System Letter Fluency (DKEFS-LF), Trail Making Test part B (TMT-B) and a EF global composite (EF-GC) were used to assess EF. All participants passed performance validity testing. 3X2 ANOVAs were conducted to determine the effect of TBI and bilingualism/monolingualism on EF performances.

Results

Main effects were found between groups (control and TBI groups) on SCW, p = .046, ηp² = .07, TMT-B, p = .042, ηp² = .07, and EF-GC, p = .005, ηp² = .13; the 6-month TBI group performed worse than controls on TMT-B and EF-GC. Main effects were found for bilingualism/ monolingualism on SCW, p = .012, ηp² = .07, and TMT-B, p = .034, ηp² = .05; monolingual participants performed better than bilingual participants. No significant interactions between TBI and language were found.

Conclusion

The TBI group underperformed on SCW, TMT-B, and EF-GC compared to controls; relative to monolinguals, bilinguals underperformed on the SCW and TMT-B only. In conclusion, our findings seem to suggest that monolinguals have better cognitive flexibility compared to bilinguals that result in better EF performances.

B-70 The Effect of Bilingualism on Trail Making Test Performance in Traumatic Brain Injury Survivors and Healthy Adults

Objective

Traumatic brain injury (TBI) is associated with a number of cognitive deficits. Language factors also impact neurocognitive performance. We examined the effects of TBI and bilingualism/monolingualism on a test of attention and executive functioning (Trail Making Test; TMT).

Method

The sample (N = 96) consisted of 36 healthy controls (19 bilingual; 17 monolingual), 34 acute TBI participants (12 bilingual; 21 monolingual), and 27 chronic TBI participants (16 bilingual; 11 monolingual). Acute TBI participants were tested 6 months post-injury and chronic TBI participants were tested 12 months or more post-injury. 3X2 ANOVAs were conducted to determine the effect of TBI and bilingualism/monolingualism on TMT part A and B.

Results

Main effects were found between groups (i.e., control and TBI groups) on TMT A, p < .001, ηp² = .17 and TMT B, p < .05, ηp² = .09. Pairwise comparisons revealed a difference only between the control group and the 6-month TBI group, with the latter performing worse. Main effects were found for bilingualism/monolingualism on TMT A, p < .05, ηp² = .04 and TMT B, p < .05, ηp² = .05; monolingual participants performed better than bilingual participants. No interactions emerged.

Conclusion

Relative to monolinguals, bilingual participants demonstrated worse attention and executive functioning performances 6 months post-TBI; however, 12 months post-TBI, the difference was negligible.

Piezoelectrically Tuned Multimode Cavity Search for Axion Dark Matter

The μeV axion is a well-motivated extension to the standard model. The Axion Dark Matter eXperiment (ADMX) collaboration seeks to discover this particle by looking for the resonant conversion of dark-matter axions to microwave photons in a strong magnetic field. In this Letter, we report results from a pathfinder experiment, the ADMX "Sidecar," which is designed to pave the way for future, higher mass, searches. This testbed experiment lives inside of and operates in tandem with the main ADMX experiment. The Sidecar experiment excludes masses in three widely spaced frequency ranges (4202-4249, 5086-5799, and 7173-7203 MHz). In addition, Sidecar demonstrates the successful use of a piezoelectric actuator for cavity tuning. Finally, this publication is the first to report data measured using both the TM_{010} and TM_{020} modes.

Pseudorapidity Dependence of Particle Production and Elliptic Flow in Asymmetric Nuclear Collisions of p+Al, p+Au, d+Au, and ^{3}He+Au at sqrt[s_{NN}]=200 GeV

Asymmetric nuclear collisions of p+Al, p+Au, d+Au, and ^{3}He+Au at sqrt[s_{NN}]=200  GeV provide an excellent laboratory for understanding particle production, as well as exploring interactions among these particles after their initial creation in the collision. We present measurements of charged hadron production dN_{ch}/dη in all such collision systems over a broad pseudorapidity range and as a function of collision multiplicity. A simple wounded quark model is remarkably successful at describing the full data set. We also measure the elliptic flow v_{2} over a similarly broad pseudorapidity range. These measurements provide key constraints on models of particle emission and their translation into flow.

Measurements of Multiparticle Correlations in d+Au Collisions at 200, 62.4, 39, and 19.6 GeV and p+Au Collisions at 200 GeV and Implications for Collective Behavior

Recently, multiparticle-correlation measurements of relativistic p/d/^{3}He+Au, p+Pb, and even p+p collisions show surprising collective signatures. Here, we present beam-energy-scan measurements of two-, four-, and six-particle angular correlations in d+Au collisions at sqrt[s_{NN}]=200, 62.4, 39, and 19.6 GeV. We also present measurements of two- and four-particle angular correlations in p+Au collisions at sqrt[s_{NN}]=200  GeV. We find the four-particle cumulant to be real valued for d+Au collisions at all four energies. We also find that the four-particle cumulant in p+Au has the opposite sign as that in d+Au. Further, we find that the six-particle cumulant agrees with the four-particle cumulant in d+Au collisions at 200 GeV, indicating that nonflow effects are subdominant. These observations provide strong evidence that the correlations originate from the initial geometric configuration, which is then translated into the momentum distribution for all particles, commonly referred to as collectivity.

Nuclear Dependence of the Transverse-Single-Spin Asymmetry for Forward Neutron Production in Polarized p+A Collisions at sqrt[s_{NN}]=200 GeV

During 2015, the Relativistic Heavy Ion Collider (RHIC) provided collisions of transversely polarized protons with Au and Al nuclei for the first time, enabling the exploration of transverse-single-spin asymmetries with heavy nuclei. Large single-spin asymmetries in very forward neutron production have been previously observed in transversely polarized p+p collisions at RHIC, and the existing theoretical framework that was successful in describing the single-spin asymmetry in p+p collisions predicts only a moderate atomic-mass-number (A) dependence. In contrast, the asymmetries observed at RHIC in p+A collisions showed a surprisingly strong A dependence in inclusive forward neutron production. The observed asymmetry in p+Al collisions is much smaller, while the asymmetry in p+Au collisions is a factor of 3 larger in absolute value and of opposite sign. The interplay of different neutron production mechanisms is discussed as a possible explanation of the observed A dependence.

Energetics and the molecular structure of an ion-paired supramolecular system in water

The forces that bind the components of a host-guest complex to generate a stable supramolecular system are noncovalent interactions. The enthalpy of this association, Δ_asH°, usually measured using calorimetry, quantifies the magnitude of such interactions and is directly related to the stability of the supramolecular complex formed. Using Calvet calorimetry to determine the enthalpies of solution and reaction in water, the enthalpy of association was derived for a supramolecular system formed by the anionic macrocycle anti-disulfodibenzo[24]crown-8 ([DSDB24C8]^2-) and the dicationic guest paraquat [PQT]²⁺. The calorimetric results show an exothermic association process, which indicates the generation of strong interactions between the components of the ion pair. This is consistent with the formation of a stable supramolecular complex [PQT][DSDB24C8], whose spatial arrangement in aqueous solution is proposed based on spectroscopic analysis.

cis and trans influences on [Pt(SRF)(triphos)]+ complexes (SRF = polyfluorobenzothiolate)

Platinum(ii) derivatives of the tridentate ligand Ph₂PCH₂CH₂P(Ph)CH₂CH₂PPh₂ (triphos), including [Pt(SR_F)(triphos)](CF₃SO₃) R_F = C₆F₄CF₃-4 1, C₆F₅2, C₆HF₄-4 3, C₆H₄CF₃-4 4, C₆H₃F₂-2,4 5, C₆H₄F-2 6, C₆H₄F-4 7 and C₆H₅8, have been prepared and characterised.

[Short bowel syndrome in children: a diagnosis and management update]

Short bowel syndrome (SBS) refers to the sum of the functional alterations that are the result of a critical reduction in the length of the intestine, which in the absence of adequate treatment, presents as chronic diarrhea, chronic dehydration, malnutrition, weight loss, nutriment and electrolyte deficiency, along with a failure to grow that is present with greater frequency during the neonatal period. The aim was to carry out a review of the literature encompassing the definition and the most frequent causes of SBS, together with an understanding of its physiopathology, prognostic factors, and treatment. An Internet search of PubMed articles was carried out for the existing information published over the last 20 years on SBS in children, using the keywords "short bowel syndrome". From a total of 784 potential articles, 82 articles were chosen for the literature review. The treatment of patients presenting with SBS is quite a challenge and therefore it is necessary to establish multidisciplinary management with a focus on maintaining optimal nutritional support that covers the necessities of growth and development and at the same time provides a maximum reduction of short, medium, and long-term complications. The diagnosis and treatment of a child with SBS require a team of professionals that are experts in gastroenterologic, pediatric, and nutritional management. The outcome for the child will be directly related to opportune management, as well as to the length of the intestinal resection and the presence or absence of the ileocecal valve.

Molecular analysis ofMycobacterium tuberculosis phosphate specific transport system in Mycobacterium smegmatis. Characterization of recombinant 38 kDa (PstS-1)

The functionality of the putative Mycobacterium tuberculosis phosphate transport operon was studied by operon- lacZ promoterless fusions in Mycobacterium smegmatis. The expression of the operon genes was evaluated in transformed M. smegmatis growing in medium with low and high phosphate concentration. Although the gene fusions expressed beta-galactosidase in medium with phosphate, a higher activity was detected in bacteria growing in medium with low phosphate. In contrast, alkaline phosphatase activity from M. smegmatis was detected only in bacteria growing in medium with low phosphate. The expression of the operon genes was driven by a promoter located 5' upstream from the start codon of the pstB gene. A second putative internal promoter 5' upstream of the pstS-1 gene was also detected. Furthermore, comparative analysis between the native and recombinant PstS-1 proteins showed that they were very similar. Like the native protein, the recombinant protein was also secreted to the culture medium as a glycosylated band. The results show that M. smegmatis recognized phosphate regulatory signals of the M. tuberculosis phosphate transport operon genes, and open the possibility to study gene phosphate regulation in mycobacteria.

[Criteria for pharmacologic quality in artificial nutritional support applied in Peru]

This is a report on the metabolic consequences derived from widely using a parenteral nutrition scheme in Peru. That scheme was in disagreement with internationally accepted principles. Its lack of capacity to achieve anabolism is demonstrated. Enteral and parenteral nutrition schemes that clearly achieve anabolism are shown as well as the notorious contrast with the parenteral nutrition scheme referred to previously. These facts set up the basis of the Formulary of Nutritional Support Units of Instituto Peruano de Seguridad Social.

[Helicobacter pylori: can it be a contributing factor in peptic ulcer in childhood?]

Helicobacter pylori is a recently identified microorganisms which is thought to be the causing agent of the peptic acid disease in children as well as in adults. It is currently accepted that frequent relapses of this illness in spite of an adequate treatment can be associated to the faulty eradication of this bacteria. This article outlines the characteristics of H. pylori, its incidence, pathogenesis, as well as the current diagnostic methods used and the treatment applied.

[Coronary arteriovenous fistula. Considerations on differential diagnosis]

Review is made of the literature of coronary arteriovenous fistula, since its first description up to 1975; we mention the most important points treated by each author. Two cases are studied clinically, by entheterization and coronariography. We take into consideration the differential diagnosis with patent ductus arteriosus, ventricular septal defect with aortic insufficiency, and rupture of congenital aneurysm sinus of valsalva to right cavities. The result of these studies is that, if an atypical continous murmur for an arterial duct is present, we may suspect a coronary fistula as a first possibility, since an aneurysm of valsalva's sinus is a rare entity.