Cultured hepatoma cells for the study of enzyme regulation: induction of ornithine decarboxylase by insulin and asparagine

The induction and decay of ornithine decarboxylase (ODC) by insulin and asparagine in cultures of H4-II-EC3 (H35) hepatoma cells was studied in a modified Waymouth medium in the presence of fetal bovine serum (FBS) and in serum-free media. The insulin response was enhanced by the presence of asparagine although the effect of asparagine was not so much on the initial increase as it was on a slowing of the decline after the maximum was reached at 6 to 8 h after the supplements were added together with fresh medium. In all cases the initial ODC activity was zero at zero time for addition of media and supplements, and, after reaching the maximum, activity declined to near zero by 24 h. Fetal bovine serum gave induction that followed a similar time course but was inferior to the combination of insulin plus asparagine and, in fact, FBS inhibited the latter response. Putrescine (the product formed from ornithine by ODC), at 10(-5) M, markedly inhibited the induction of ODC by insulin or FBS, but the inhibition was less when asparagine was present.     

Effect of Text Message,Phone Call,and In-Person Appointment Reminders on Uptake of Repeat HIV Testing among Outpatients Screened for Acute HIV Infection in Kenya: A Randomized Controlled Trial

BackgroundFollowing HIV-1 acquisition, many individuals develop an acute retroviral syndrome and a majority seek care. Available antibody testing cannot detect an acute HIV infection, but repeat testing after 2–4 weeks may detect seroconversion. We assessed the effect of appointment reminders on attendance for repeat HIV testing.MethodsWe enrolled, in a randomized controlled trial, 18–29 year old patients evaluated for acute HIV infection at five sites in Coastal Kenya (ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01876199","term_id":"NCT01876199"}}NCT01876199). Participants were allocated 1:1 to either standard appointment (a dated appointment card) or enhanced appointment (a dated appointment card plus SMS and phone call reminders, or in-person reminders for participants without a phone). The primary outcome was visit attendance, i.e., the proportion of participants attending the repeat test visit. Factors associated with attendance were examined by bivariable and multivariable logistic regression.ConclusionsAppointment reminders through SMS, phone calls and in-person reminders increased the uptake of repeat HIV test by forty percent. This low-cost intervention could facilitate detection of acute HIV infections and uptake of recommended repeat testing.

Trial Registration

Clinicaltrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01876199","term_id":"NCT01876199"}}NCT01876199     

Enhanced immune function does not depress reproductive output

Costs of reproduction might be mediated by a physiological (resource allocation) trade-off between immune function and reproductive effort, and several recent studies have shown that an experimental increase in reproductive effort is associated with decreased immune function. Here we test the complementary prediction of this hypothesis: that increased immune function (specific antibody production) depresses reproductive output. Female European starlings (Sturnus vulgaris) were injected with a non-pathogenic antigen (sheep red blood cells) following completion of laying of their first clutch, to stimulate an in vivo humoral immune response (primary antibody production). We induced laying of a second clutch by removing the first clutch, and assessed changes in reproductive performance in individual females pre- and post-treatment. Injection of sheep red blood cells produced a significant antibody response in 96% (n=29) of treated females, with titres comparable to previous studies (range 1 to 7). However, increased antibody production did not decrease primary or secondary female reproductive effort (re-laying interval, egg size, clutch size, chick growth or fledging success), compared with control, saline-injected birds (n=22). These data do not support a simple resource allocation model for the cost of reproduction, based on a reciprocal, negative relationship between resources allocated to immune function and reproduction.     

Phenotypic and functional abnormalities of bone marrow-derived dendritic cells in systemic lupus erythematosus

Introduction  

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by autoreactive T and B cells, which are believed to be secondary to deficient dendritic cells (DCs). However, whether DC abnormalities occur during their development in the bone marrow (BM) or in the periphery is not known.     

Metaproteomic analysis of a winter to spring succession in coastal northwest Atlantic Ocean microbial plankton

In this study, we used comparative metaproteomics to investigate the metabolic activity of microbial plankton inhabiting a seasonally hypoxic basin in the Northwest Atlantic Ocean (Bedford Basin). From winter to spring, we observed a seasonal increase in high-affinity membrane transport proteins involved in scavenging of organic substrates; Rhodobacterales transporters were strongly associated with the spring phytoplankton bloom, whereas SAR11 transporters were abundant in the underlying waters. A diverse array of transporters for organic compounds were similar to the SAR324 clade, revealing an active heterotrophic lifestyle in coastal waters. Proteins involved in methanol oxidation (from the OM43 clade) and carbon monoxide (from a wide variety of bacteria) were identified throughout Bedford Basin. Metabolic niche partitioning between the SUP05 and ARCTIC96BD-19 clades, which together comprise the Gamma-proteobacterial sulfur oxidizers group was apparent. ARCTIC96BD-19 proteins involved in the transport of organic compounds indicated that in productive coastal waters this lineage tends toward a heterotrophic metabolism. In contrast, the identification of sulfur oxidation proteins from SUP05 indicated the use of reduced sulfur as an energy source in hypoxic bottom water. We identified an abundance of Marine Group I Thaumarchaeota proteins in the hypoxic deep layer, including proteins for nitrification and carbon fixation. No transporters for organic compounds were detected among the thaumarchaeal proteins, suggesting a reliance on autotrophic carbon assimilation. In summary, our analyses revealed the spatiotemporal structure of numerous metabolic activities in the coastal ocean that are central to carbon, nitrogen and sulfur cycling in the sea.     

Relative shortening and functional tethering of spinal cord in adolescent scoliosis – Result of asynchronous neuro-osseous growth, summary of an electronic focus group debate of the IBSE

There is no generally accepted scientific theory for the causes of adolescent idiopathic scoliosis (AIS). As part of its mission to widen understanding of scoliosis etiology, the International Federated Body on Scoliosis Etiology (IBSE) introduced the electronic focus group (EFG) as a means of increasing debate on knowledge of important topics. This has been designated as an on-line Delphi discussion. The Statement for this debate was written by Dr WCW Chu and colleagues who examine the spinal cord to vertebral growth interaction during adolescence in scoliosis. Using the multi-planar reconstruction technique of magnetic resonance imaging they investigated the relative length of spinal cord to vertebral column including ratios in 28 girls with AIS (mainly thoracic or double major curves) and 14 age-matched normal girls. Also evaluated were cerebellar tonsillar position, somatosensory evoked potentials (SSEPs), and clinical neurological examination. In severe AIS compared with normal controls, the vertebral column is significantly longer without detectable spinal cord lengthening. They speculate that anterior spinal column overgrowth relative to a normal length spinal cord exerts a stretching tethering force between the two ends, cranially and caudally leading to the initiation and progression of thoracic AIS. They support and develop the Roth-Porter concept of uncoupled neuro-osseous growth in the pathogenesis of AIS which now they prefer to term ' asynchronous neuro-osseous growth'. Morphological evidence about the curve apex suggests that the spinal cord is also affected, and a 'double pathology' is suggested. AIS is viewed as a disorder with a wide spectrum and a common neuroanatomical abnormality namely, a spinal cord of normal length but short relative to an abnormally lengthened anterior vertebral column. Neuroanatomical changes and/or abnormal neural function may be expressed only in severe cases. This asynchronous neuro-osseous growth concept is regarded as one component of a larger concept. The other component relates to the brain and cranium of AIS subjects because abnormalities have been found in brain (infratentorial and supratentorial) and skull (vault and base). The possible relevance of systemic melatonin-signaling pathway dysfunction, platelet calmodulin levels and putative vertebral vascular biology to the asynchronous neuro-osseous growth concept is discussed. A biomechanical model to test the spinal component of the concept is in hand. There is no published research on the biomechanical properties of the spinal cord for scoliosis specimens. Such research on normal spinal cords includes movements (kinematics), stress-strain responses to uniaxial loading, and anterior forces created by the stretched cord in forward flexion that may alter sagittal spinal shape during adolescent growth. The asynchronous neuro-osseous growth concept for the spine evokes controversy. Dr Chu and colleagues respond to five other concepts of pathogenesis for AIS and suggest that relative anterior spinal overgrowth and biomechanical growth modulation may also contribute to AIS pathogenesis.     

Expression of the alpha 1-proteinase inhibitor gene family during evolution of the genus Mus

alpha 1-Proteinase inhibitors (alpha 1-PIs) are members of the serpin superfamily of proteinase inhibitors, and are important in the maintenance of homeostasis in a wide variety of animal taxa. Previous studies have shown that in mice (genus Mus), evolution of alpha 1-PIs is characterized by gene amplification, region-specific concerted evolution, and rapid accumulation of amino acid substitutions. The latter occurs primarily in the reactive center, which is the region of the alpha 1-PI molecule that determines the inhibitor's specificity for target proteinases. The P1 residue within the reactive center, which is methionine in so-called orthodox alpha 1-PIs and an amino acid other than methionine in unorthodox alpha 1-PIs, is a primary determinant of inhibitor specificity. In the present study, we find that the expression of mRNAs encoding unorthodox alpha 1-PIs is polymorphic within Mus species, i.e., among individuals or inbred strains. This is in striking contrast to mRNAs that encode orthodox alpha 1-PIs, whose concentrations are relatively invariant. The intraspecies variations in mRNA expression represent polymorphisms in the structure of the alpha 1- PI gene family. The results, taken together with previously described aspects of alpha 1-PI evolution, indicate that the dissimilar levels of polymorphism exhibited by orthodox and unorthodox alpha 1-PIs, which likely have distinct physiological functions, may reflect different levels of selective constraint. The significance of this finding to the evolution of gene families is discussed.      

Effect of cartilage proteoglycans on human collagenase activities

No significant inhibition of purified rheumatoid synovial collagenase was found when this enzyme was assayed in the presence of porcine or human cartilage proteoglycans. Reaction mixtures containing up to twice the amount of proteoglycan compared to that of collagen, w/w,, had little effect on collagen degradation as judged by the reconstituted [¹⁴C] collagen fibril assay and polyacrylamide gel electrophoresis. Proteoglycans were not degraded by the synovial collagenase preparation. Although the human collagenases derived from rheumatoid synovium, gastric mucosa, skin and granulocytes showed some reduction in activity when exposed to aggregated proteoglycans at high concentrations, disaggregated proteoglycans had no inhibitory effect. It is concluded that cartilage proteoglycans do not directly inhibit human collagenases in vitro, but in vivo they may provide some physical barriers which might limit the accessibility of the enzyme to its collagen substrate.     

Action of rheumatoid synovial collagenase on cartilage collagen. Different susceptibilities of cartilage and tendon collagen to collagenase attack.

The action of purified rheumatoid synovial collagenase on purified cartilage collagen, alpha-1(II)-3, in solution at 25 degrees C has been characterised. The enzyme attacked cartilage collagen in solution producing a 58% reduction in specific viscosity and resulting in the appearance of two reaction products which represented approximately three-quarter and one-quarter fragments of the intact molecule as shown by disc electrophoresis in polyacrylamide gels containing sodium dodecyl sulphate. The alpha-chain fragments which comprised each of these components corresponded to molecular weights of approximately 74000 and 21000. Electron microscopy of segment-long-spacing crystallites of the reaction products revealed three-quarter (TC-a) and one-quarter (TC-b) length fragments, and permitted accurate localization of the cleavage locus between bands 41 and 42 (I-41). This cleavage site and the formation of TC-a and TC-b reaction products are very similar to those found for type-I collagen substrates. Cartilage collagen in solution was found to be more resistant to collagenase attack than tendon collagen, the rate of cartilage collagen degradation being six times slower than that for tendon collagen, as judged by viscometry. The mid-point melting temperatures (T-m) for lathyritic cartilage and tendon collagen were 40.5 and 41.5 degrees C, and for the collagenase-produced reaction products 38.5 and 37.5 degrees C, respectively. The significance of these findings is discussed in relation to the structure of type I and II collagens.