Autolysis Promotes the Extension Capacity of Zea mays Coleoptile Cell Walls in Response to Acid pH Solutions

The relationship between autolytic degradation of ß(1–3),(1–4)-D-glucanand acid pH-induced extension of isolated Zea mays cell wallshas been investigated using a constant-load extension technique.Acidic buffer (4.5) was able to induce an additional extension(E_a) on cell walls already extended at pH 6.8 buffer under a20 g-mass load, indicating that the additional extension (E_a)was the parameter that better represented the effect of thedifferent treatments on the mechanical properties of maize coleoptilecell walls. The additional extension in response to acidic pHwas higher when cell walls had been previously autolysed for24 h at pH 5.5. Furthermore, the acid-pH effect was dependenton the presence during the constant load extension of some thermo-labilefactors, suggesting the participation of expansins. Acid pHincreased E_a of native cell walls through an increase in theplastic extension (E_p) in agreement with a one step mechanismleading directly to irreversible (plastic) wall extension assuggested by Cosgrove (1977). The autolytic degradation of ß(1–3),(1–4)-D-glucan was also able to modify the mechanicalproperties of maize coleoptile cell walls increasing its elasticextension (E_e) in response to pH 4.5 buffer but that modificationonly leads to an increase in wall extension when expansins areactive, suggesting a cooperation between ß-glucanturnover and expansin action. (Received August 5, 1998; Accepted March 16, 1999)     

A Phase I Double Blind,Placebo-Controlled,Randomized Study of the Safety and Immunogenicity of an Adjuvanted HIV-1 Gag-Pol-Nef Fusion Protein and Adenovirus 35 Gag-RT-Int-Nef Vaccine in Healthy HIV-Uninfected African Adults

Background

Sequential prime-boost or co-administration of HIV vaccine candidates based on an adjuvanted clade B p24, RT, Nef, p17 fusion protein (F4/AS01) plus a non-replicating adenovirus 35 expressing clade A Gag, RT, Int and Nef (Ad35-GRIN) may lead to a unique immune profile, inducing both strong T-cell and antibody responses.

Methods

In a phase 1, double-blind, placebo-controlled trial, 146 healthy adult volunteers were randomized to one of four regimens: heterologous prime-boost with two doses of F4/AS01_E or F4/AS01_B followed by Ad35-GRIN; Ad35-GRIN followed by two doses of F4/AS01_B; or three co-administrations of Ad35-GRIN and F4/AS01_B. T cell and antibody responses were measured.

Results

The vaccines were generally well-tolerated, and did not cause serious adverse events. The response rate, by IFN-γ ELISPOT, was greater when Ad35-GRIN was the priming vaccine and in the co-administration groups. F4/AS01 induced CD4+ T-cells expressing primarily CD40L and IL2 +/- TNF-α, while Ad35-GRIN induced predominantly CD8+ T-cells expressing IFN-γ +/- IL2 or TNF-α. Viral inhibition was induced after Ad35-GRIN vaccination, regardless of the regimen. Strong F4-specific antibody responses were induced. Immune responses persisted at least a year after the last vaccination. The complementary response profiles, characteristic of each vaccine, were both expressed after co-administration.

Conclusion

Co-administration of an adjuvanted protein and an adenovirus vector showed an acceptable safety and reactogenicity profile and resulted in strong, multifunctional and complementary HIV-specific immune responses.

Trial Registration

ClinicalTrials.gov NCT01264445     

Alterations in Perivascular Sympathetic and Nitrergic Innervation Function Induced by Late Pregnancy in Rat Mesenteric Arteries

Background and Purpose

We investigated whether pregnancy was associated with changed function in components of perivascular mesenteric innervation and the mechanism/s involved.

Experimental Approach

We used superior mesenteric arteries from female Sprague-Dawley rats divided into two groups: control rats (in oestrous phase) and pregnant rats (20 days of pregnancy). Modifications in the vasoconstrictor response to electrical field stimulation (EFS) were analysed in the presence/absence of phentolamine (alpha-adrenoceptor antagonist) or L-NAME (nitric oxide synthase-NOS- non-specific inhibitor). Vasomotor responses to noradrenaline (NA), and to NO donor DEA-NO were studied, NA and NO release measured and neuronal NOS (nNOS) expression/activation analysed.

Key Results

EFS induced a lower frequency-dependent contraction in pregnant than in control rats. Phentolamine decreased EFS-induced vasoconstriction in segments from both experimental groups, but to a greater extent in control rats. EFS-induced vasoconstriction was increased by L-NAME in arteries from both experimental groups. This increase was greater in segments from pregnant rats. Pregnancy decreased NA release while increasing NO release. nNOS expression was not modified but nNOS activation was increased by pregnancy. Pregnancy decreased NA-induced vasoconstriction response and did not modify DEA-NO-induced vasodilation response.

Conclusions and Implications

Neural control of mesenteric vasomotor tone was altered by pregnancy. Diminished sympathetic and enhanced nitrergic components both contributed to the decreased vasoconstriction response to EFS during pregnancy. All these changes indicate the selective participation of sympathetic and nitrergic innervations in vascular adaptations produced during pregnancy.     

Consider the Source: Adolescents and Adults Similarly Follow Older Adult Advice More than Peer Advice

Individuals learn which of their actions are likely to be rewarded through trial and error. This form of learning is critical for adapting to new situations, which adolescents frequently encounter. Adolescents are also greatly influenced by their peers. The current study tested the extent to which adolescents rely on peer advice to guide their actions. Adolescent and young adult participants completed a probabilistic learning task in which they chose between four pairs of stimuli with different reinforcement probabilities, with one stimulus in each pair more frequently rewarded. Participants received advice about two of these pairs, once from a similarly aged peer and once from an older adult. Crucially, this advice was inaccurate, enabling the dissociation between experience-based and instruction-based learning. Adolescents and adults learned equally well from experience and no age group difference was evident in the overall influence of advice on choices. Surprisingly, when considering the source of advice, there was no evident influence of peer advice on adolescent choices. However, both adolescents and adults were biased toward choosing the stimulus recommended by the older adult. Contrary to conventional wisdom, these data suggest that adolescents may prioritize the advice of older adults over that of peers in certain decision-making contexts.     

Mycobacterium tuberculosis Genotypes Determined by Spoligotyping to Be Circulating in Colombia between 1999 and 2012 and Their Possible Associations with Transmission and Susceptibility to First-Line Drugs

Introduction

Tuberculosis (TB) remains a primary public health problem worldwide. The number of multidrug-resistant tuberculosis (MDR TB) cases has increased in recent years in Colombia. Knowledge of M. tuberculosis genotypes defined by spoligotyping can help determine the circulation of genotypes that must be controlled to prevent the spread of TB.

Objective

To describe the genotypes of M. tuberculosis using spoligotyping in resistant and drug-sensitive isolates and their possible associations with susceptibility to first-line drugs.

Methods

An analytical observational study was conducted that included 741 isolates of M. tuberculosis from patients. The isolates originated from 31 departments and were obtained by systematic surveillance between 1999 and 2012.

Results

In total 61.94% of the isolates were resistant to 1 or more drugs, and 147 isolates were MDR. In total, 170 genotypes were found in the population structure of Colombian M. tuberculosis isolates. The isolates were mainly represented by four families: LAM (39.9%), Haarlem (19%), Orphan (17%) and T (9%). The SIT42 (LAM 9) was the most common genotype and contained 24.7% of the isolates, followed by the genotypes SIT62 (Haarlem1), SIT53 (T1), and SIT50 (H3). A high clustering of isolates was evident with 79.8% of the isolates classified into 32 groups. The Beijing family was associated with resistant isolates, whereas the Haarlem and T families were associated with sensitive isolates. The Haarlem family was also associated with grouped isolates (p = 0.031).

Conclusions

A high proportion (approximately 80%) of isolates was found in clusters; these clusters were not associated with resistance to first-line drugs. The Beijing family was associated with drug resistance, whereas the T and Haarlem families were associated with susceptibility in the Colombian isolates studied.     

Childhood Symptoms of ADHD Overrule Comorbidity in Relation to Psychosocial Outcome at Age 15: A Longitudinal Study

Objective

Neurodevelopmental problems (NDPs) may influence the transition from childhood to adolescence. Our aim was to study long-term psychosocial outcomes of NDPs, focusing on ADHD.

Method

Data was collected through a telephone interview with parents of twins at ages 9 or 12 years. NDP screen-positive children were clinically assessed at age 15; N = 450. Psychosocial outcome concerning peers, school, internalizing problems, antisocial behavior, alcohol misuse, drug misuse, and impaired daily functioning was examined.

Results

Even after controlling for other NDP comorbidity, screen-positivity for ADHD doubled or tripled the odds of later psychosocial problems. When controlling for parental education level, the significant effect of ADHD remained only for antisocial behavior and impaired daily functioning.

Conclusions

Signs of NDPs as well as other psychiatric diagnoses at ages 9 or 12 years are associated with a more problematic adolescence. However, despite the presence of comorbidity, early ADHD symptoms stand out as the most important risk factor for later antisocial development and impaired daily functioning.     

Endemic Viruses of Squirrel Monkeys (Saimiri spp.)

Nonhuman primates are the experimental animals of choice for the study of many human diseases. As such, it is important to understand that endemic viruses of primates can potentially affect the design, methods, and results of biomedical studies designed to model human disease. Here we review the viruses known to be endemic in squirrel monkeys (Saimiri spp.). The pathogenic potential of these viruses in squirrel monkeys that undergo experimental manipulation remains largely unexplored but may have implications regarding the use of squirrel monkeys in biomedical research.Abbreviations: HTLV1, human T-cell leukemia virus type 1; HVS, herpesvirus saimiri; IPF, idiopathic pulmonary fibrosis; SaHV, Saimiriine herpesvirus; SFV, simian foamy virus; SM-CMV, squirrel monkey cytomegalovirus; SMPyV, squirrel monkey polyomavirus; SMRV, squirrel monkey retrovirusThe similarity between the nonhuman primate and human immune systems is a key advantage in the use of nonhuman primates compared with other mammalian models of human disease.^{13,71,88,94,103,113,125} In addition, the diversity of environmental and infectious disease agents encountered by primates is similar to that of humans, providing nonhuman primates a comparable level of biologic complexity.¹ Old World primates, such as macaques and baboons, and New World primates, including squirrel monkeys and marmosets, are commonly used in biomedical research. Squirrel monkeys (Saimiri spp.) are neotropical primates native to the forests of Central and South America. Of the 7 species of squirrel monkey, 3 (S. oerstedii, S. vanzolinii, and S. ustus) are classified as endangered, vulnerable to extinction in the wild, or near threatened, whereas the remaining 4 (S. boliviensis, S. cassiquiarensis, S. macrodon, and S. sciureus) are not endangered, although the S. cassiquiarensis albigena subspecies is near threatened^52,81 (Figure 1). In South America, where squirrel monkeys are indigenous, breeding colonies of S. sciureus have been maintained at the Pasteur Institute in French Guiana and at the Oswaldo Cruz Foundation in Brazil.^7,12 In the United States, the Squirrel Monkey Breeding and Research Resource, an NIH-sponsored national research resource, maintains breeding colonies for S. boliviensis boliviensis, S. sciureus sciureus, and S. boliviensis peruviensis.Open in a separate windowFigure 1.Taxonomy of Saimiri species with associated IUCN designations.^52,81Squirrel monkeys adapt easily to laboratory housing and can be housed in smaller spaces than can Old World primates.¹ Unlike when working with Old World primates, particularly macaques, no additional personnel protective equipment is necessary when working with squirrel monkeys beyond that recommended for working with other New World primates.⁹² Their small size, combined with the reduced need for personnel protective equipment during handling, make squirrel monkeys attractive species for model development and for studies of viral pathogenesis, which cost approximately 30% to 40% less than comparable studies in macaques.¹ The likelihood of zoonotic transmission of infectious pathogens is considerably less than that associated with macaques and the risk of Macacine herpesvirus 1 (B virus) is nonexistent, given that neotropical primates do not harbor this lethal virus.¹ These factors are increasingly important in the current climate of limited grant funding for biomedical research and emphasis on safety for laboratory personnel. The limited availability of immunologic reagents with specificity for neotropical primates has hindered broader use of squirrel monkeys in biomedical research, compared with that of the more commonly used Old World primates. In addition, the small size of neotropical primates limits the volume of blood that can be collected at any one time. To abrogate these limitations, the NIH Nonhuman Primate Reagent Resource (www.nhpreagents.org) provides an increasing repertoire of agents that have been characterized for immunologic studies of neotropical primates.⁸⁹Squirrel monkeys are used in numerous aspects of biomedical research, including studies of viral persistence, neuroendocrinology, infectious diseases, cancer treatments, vaccine development, gene expression, and reproductive physiology.¹¹⁷ The similarity between the squirrel monkey immune system and that of humans means that, as with macaques, there is a high likelihood that research outcomes will recapitulate what occurs in human diseases.^13,71,87,94 This is particularly true for the study of several notable infectious diseases, including malaria, Creutzfeldt–Jakob disease, and human T-cell leukemia virus type 1 (HTLV1) infection.^19,56,128 For these diseases, squirrel monkeys are the model system of choice for studying pathogenesis, experimental treatments, and strategies for prevention.Squirrel monkeys are recognized as some of the most susceptible nonhuman primate species for the experimental transmission of Creutzfeldt–Jakob disease and other transmissible spongiform encephalopathies that cause chronic wasting disease.^11,72,98,130 The experimental infection of squirrel monkeys with HTLV1 has led to their use in vaccine development and chemotherapy research directed against HTLV1.^44,57,58,82 In addition, squirrel monkeys are an important model for studying the immunology of malaria and for testing vaccines against several Plasmodium species.^19,20,68,114 Furthermore, squirrel monkeys have been used in pharmacologic research to raise HDL levels to prevent atherosclerosis and reduce the risk of coronary heart disease.⁶ As the use of squirrel monkeys increases, especially for infectious disease research, accurate information about the endemic viral infections of squirrel monkeys is needed because of the potential for zoonotic transfer of these viruses to humans (and vice versa) and to understand the potential influence these agents may have on research involving other infectious pathogens diseases and immunosuppressive drugs.     

Methods for Comparing Nutrients in Beebread Made by Africanized and European Honey Bees and the Effects on Hemolymph Protein Titers

Honey bees obtain nutrients from pollen they collect and store in the hive as beebread. We developed methods to control the pollen source that bees collect and convert to beebread by placing colonies in a specially constructed enclosed flight area. Methods were developed to analyze the protein and amino acid composition of the pollen and beebread. We also describe how consumption of the beebread was measured and methods used to determine adult worker bee hemolymph protein titers after feeding on beebread for 4, 7 and 11 days after emergence. Methods were applied to determine if genotype affects the conversion of pollen to beebread and the rate that bees consume and acquire protein from it. Two subspecies (European and Africanized honey bees; EHB and AHB respectively) were provided with the same pollen source. Based on the developed methods, beebread made by both subspecies had lower protein concentrations and pH values than the pollen. In general, amino acid concentrations in beebread made by either EHB or AHB were similar and occurred at higher levels in beebread than in pollen. Both AHB and EHB consumed significantly more of the beebread made by AHB than by EHB. Though EHB and AHB consumed similar amounts of each type of beebread, hemolymph protein concentrations in AHB were higher than in EHB. Differences in protein acquisition between AHB and EHB might reflect environmental adaptations related to the geographic region where each subspecies evolved. These differences could contribute to the successful establishment of AHB populations in the New World because of the effects on brood rearing and colony growth.