A multi-organ chip with matured tissue niches linked by vascular flow

Engineered tissues can be used to model human pathophysiology and test the efficacy and safety of drugs. Yet, to model whole-body physiology and systemic diseases, engineered tissues with preserved phenotypes need to physiologically communicate. Here we report the development and applicability of a tissue-chip system in which matured human heart, liver, bone and skin tissue niches are linked by recirculating vascular flow to allow for the recapitulation of interdependent organ functions. Each tissue is cultured in its own optimized environment and is separated from the common vascular flow by a selectively permeable endothelial barrier. The interlinked tissues maintained their molecular, structural and functional phenotypes over 4 weeks of culture, recapitulated the pharmacokinetic and pharmacodynamic profiles of doxorubicin in humans, allowed for the identification of early miRNA biomarkers of cardiotoxicity, and increased the predictive values of clinically observed miRNA responses relative to tissues cultured in isolation and to fluidically interlinked tissues in the absence of endothelial barriers. Vascularly linked and phenotypically stable matured human tissues may facilitate the clinical applicability of tissue chips.

milliPillar: A Platform for the Generation and Real-Time Assessment of Human Engineered Cardiac Tissues

Engineered cardiac tissues derived from human induced pluripotent stem cells (iPSCs) are increasingly used for drug discovery, pharmacology and in models of development and disease. While there are numerous platforms to engineer cardiac tissues, they often require expensive and nonconventional equipment and utilize complex video-processing algorithms. As a result, only specialized academic laboratories have been able to harness this technology. In addition, methodologies and tissue features have been challenging to reproduce between different groups and models. Here, we describe a facile technology (milliPillar) that covers the entire pipeline required for studies of engineered cardiac tissues. We include methodologies for (i) platform fabrication, (ii) cardiac tissue generation, (iii) electrical stimulation, (iv) automated real-time data acquisition, and (v) advanced video analyses. We validate these methodologies and demonstrate the versatility of the platform by showcasing the fabrication of tissues in different hydrogel materials and using cardiomyocytes derived from different iPSC lines in combination with different types of stromal cells. We also validate the long-term culture of tissues within the platform and provide protocols for automated analysis of force generation and calcium flux using both brightfield and fluorescence imaging. Lastly, we demonstrate the compatibility of the milliPillar platform with electromechanical stimulation to enhance cardiac tissue function. We expect that this resource will provide a valuable and user-friendly tool for the generation and real-time assessment of engineered human cardiac tissues for basic and translational studies.

Are point-of-care urine albumin-creatinine ratio measurements accurate in the critically ill?

BACKGROUND

In the critical care environment, elevated albuminuria values show capacity to reflect illness severity and predict mortality and hence assessing albumin/creatinine ratio (ACR) at the bedside has potential clinical benefit Point-of-care (POC) analysers offer rapid results but may be less accurate then laboratory analysis.

METHODS

Critically ill adult patients with a urinary catheter in situ had albumin, creatinine, and ACR measurements performed via laboratory and POC analysis. Data are presented as mean (standard deviation) or median [interquartile range]. Measurement agreement was assessed by Lin's concordance correlation coefficient, Bland Altman 95% limits of agreement, and classification by Cohen's kappa statistic.

RESULTS/FINDINGS

Albumin, creatinine, and ACR analysis was performed for 30 patients. Lin's correlation coefficient showed 'substantial' agreement for albumin and ACR and 'almost perfect' agreement for creatinine for POC vs laboratory analysis. POC vs laboratory analysis also showed poor agreement for identification of normal ACR (>1 mg/mmol) and mild urine ACR (1-3 mg/mmol) and 'substantial' agreement for moderately increased urine ACR (3-30 mg/mmol).

CONCLUSIONS

ACR POC values appear to provide an accurate and rapid method that has potential to provide an early indication of injury severity and mortality risk in the critically ill.

Evaluation of the cognitive benefits of intrathecal baclofen pump implantation in people with intractable multiple sclerosis related spasticity

BACKGROUND

Spasticity is a common problematic symptom in Multiple Sclerosis with over one third of patients failing first line therapies. Intrathecal baclofen is a safe and efficacious option for treatment resistant spasticity. Anecdotally patients report improved concentration/cognitive performance when switching to intrathecal baclofen (ITB) from systemic medications.

AIM

To explore whether subjects who proceed with ITB pump implantation for spasticity management and reduce oral anti-spasticity agents will have improved cognitive function.

METHODS

Subjects were admitted for trial of ITB via lumbar puncture and subsequent pump implantation. Spasticity and cognitive measures before ITB trial and 3 months post implant were recorded. Paired t-test or Wilcoxon Signed Ranks test was used for within subject change and effect sizes (Cohen's d_z) were calculated. Subgroup analysis of those on ≥2, or ≤ 1 spasticity medications at baseline was performed.

RESULTS

27 subjects with MS completed per protocol. Mean age 46 years [26 - 56], disease duration 15 years [6 - 26], RRMS = 3, SPMS = 17 and PPMS=7. The majority were on multiple spasticity medications. Spasticity scores significantly improved post pump implant. Mean ITB dose at 3 months was 143 mcg / day and 19 discontinued all other treatments for spasticity. There was no deterioration on any cognitive or mood measure. An improvement of moderate effect size was found in Backwards Digit Span (d=0.41, p=0.059) and HADS - anxiety (d=0.37, p=0.097). Fatigue Severity Scale score decreased substantially (d=0.81, p=0.005). Small improvements in Symbol Digit Modalities Test score (d=0.24) and Sustained Attention to Response Task response time (d=0.23) were non-significant. Performance on other measures did not change. Effect sizes were larger in subgroup on ≥2 oral spasticity medications at baseline, compared to the group on ≤1 medication (SDMT, d=0.42 vs d=0.07; Backwards digit span 0.45 vs 0.28; HADS-anxiety 0.39 vs 0.32; HADS-depression d=0.32 vs 0.05 and FSS, d= 1.14 vs 0.42).

CONCLUSIONS

In a pilot study exploring the impact of ITB on cognition, spasticity scores improved universally and beneficial effects on some measures of fatigue, anxiety, auditory attention and verbal working memory were found. Improvement of speed of processing in those withdrawing higher doses of oral medication was also demonstrated suggesting that switching to ITB has added cognitive and psychological benefits for people with MS.

Dynamic cluster quantum Monte Carlo simulations of a two-dimensional Hubbard model with stripelike charge-density-wave modulations: interplay between inhomogeneities and the superconducting state

Using dynamic cluster quantum Monte Carlo simulations, we study the superconducting behavior of a 1/8 doped two-dimensional Hubbard model with imposed unidirectional stripelike charge-density-wave modulation. We find a significant increase of the pairing correlations and critical temperature relative to the homogeneous system when the modulation length scale is sufficiently large. With a separable form of the irreducible particle-particle vertex, we show that optimized superconductivity is obtained for a moderate modulation strength due to a delicate balance between the modulation enhanced pairing interaction, and a concomitant suppression of the bare particle-particle excitations by a modulation reduction of the quasiparticle weight.

Interferometric sensing platform with dielectric nanostructured thin films

A new interferometer-based optical sensing platform with nanostructured thin films of ZrO2 or TiO2 as sensing environment has been developed. With the application of an IC compatible Si(3)N(4) waveguide technology, Mach-Zehnder interferometer devices have been fabricated. The application of the glancing angle deposition technique allowed fabrication of nanostructured thin films as the optical sensing environment. Sensing ability of fabricated devices has been demonstrated through the refractive index measurement of a known gas. The transmission spectra and time response measurements have demonstrated a maximum phase shift of Delta phi=pi/10 and a |Delta P(out)|=0.65 dBm. Devices with TiO2 film on the sensing region performed much better than devices with ZrO2, with sensitivity twice as high.

Fiber based optical trapping of aerosols

We present the use of optical fibers to form a counter-propagating optical trap as a means of manipulating both solid and liquid aerosols. We explore the use of single and multimode fibers to achieve trapping of various particles in air, present the trapping properties of the different fiber types and compare the observed trends to those predicted by theory. Using fibers, we are able to hold suspended particles for extended periods of time and to precisely manipulate them over distances of several hundred microns. We discuss the difficulties and advantages of each fiber configuration and conclude with a demonstration that fiber based trapping offers a good candidate for studying optical binding in air.

Cognitive impairment in multiple sclerosis can be predicted by imaging early in the disease

BACKGROUND

Cognitive impairment is common in multiple sclerosis (MS) and adds significantly to the burden of the disease. The ability to predict future cognitive impairment from imaging obtained at disease onset has not been investigated.

METHODS

62 patients imaged within 3 months of a clinically isolated syndrome were assessed neuropsychologically 7 years later. Baseline and periodic MRI measures of lesions, atrophy and normal-appearing white and grey matter were regressed against neuropsychological scores to explore the best predictors of cognitive outcome.

RESULTS

28 patients had developed clinically definite MS at follow-up and a further nine met revised McDonald criteria for MS. Deficits in speed of information processing and executive function were the most common abnormalities. Poor performance correlated with high anxiety ratings. Baseline T(1) lesion metrics predicted executive deficits, and new T(2) lesions at the 3-month follow-up predicted slowed information processing. An increase in myo-inositol concentration in normal-appearing white matter over the first 3 years was associated with poor executive function.

CONCLUSIONS

MRI variables obtained at the onset of a clinically isolated syndrome can predict future development of cognitive abnormalities. Our findings may have implications in monitoring and treating patients.

Could interchangeable use of dry powder inhalers affect patients?

The aim of asthma treatment is optimal disease control. Poor asthma control results in considerable patient morbidity, as well as contributing to the considerable burden placed by the disease on healthcare budgets. There is a need for costs to be carefully scrutinised, with the switching of patients to inhaler devices with lower acquisition costs likely to be increasingly considered. However, before such practice becomes widespread, it is important to establish whether or not this could adversely impact on patients and the level of disease control. For approval to have been given, all marketed inhalers must have satisfied current regulatory requirements for devices. Full preclinical and clinical development programmes are not required when application is made for authorisation to market a new inhaler containing an existing chemical entity, although clinical equivalence testing must be used. Both beneficial and adverse effects should be tested, and the limits of equivalence must be clearly defined, based on therapeutic relevance. It should be noted that equivalence studies are invalid when the end point is not responding (i.e. at the top of the dose-response curve) and when equivalence limits approach or are equal to the magnitude of the drug effect. Approval on the basis of regulations designed to safeguard quality of dry powder inhalers does not mean that devices are interchangeable. When using an inhaler, there are many stages between the patient and the therapeutic effect, involving device design, pharmaceutical performance and patient behaviour. Regulations governing new devices cover only a few of the many factors affecting disease control. Furthermore, clinical trials to assess equivalence may not take into account factors in patient behaviour or variations in patient inhaler technique that may affect use of devices in real-life situations. When assessing the consequences of interchangeable use of dry powder inhalers on healthcare costs, it is important to ensure that the acquisition cost of the devices is not the only cost considered. Other costs that should be considered include the cost of time spent demonstrating to the patient how to use the new device, the cost of additional physician visits to address patient concerns and the management costs if disease control is adversely affected.

Patient satisfaction with psychiatric services provided by a Melbourne tertiary hospital emergency department

The mainstreaming of psychiatric services within the general healthcare system has created fundamental changes to the manner in which patients access acute psychiatric services. This change was intended to reduce the stigma associated with psychiatric diagnosis and therefore contribute to improved treatment outcomes for patients. The aim of this paper is to discuss the results of a study designed to ascertain the level of psychiatric patient satisfaction with the services received in the emergency department of a Melbourne metropolitan hospital. The results indicate a high level of satisfaction, particularly with the availability of staff with psychiatric qualifications and experience to provident treatment, support and care. The major areas of dissatisfaction identified by patients included: lengthy waiting times, lack of privacy in the triage area and negative attitudes of general staff. These findings support the argument from the literature for psychiatric consultancy services to be available in the emergency department, and further identifies the need for triage guidelines to be tailored to the needs of mental health patients and for emergency department triage staff to be appropriately educated to adequately triage these patients.

The triage of psychiatric patients in the hospital emergency department: a comparison between emergency department nurses and psychiatric nurse consultants

The triage of patients in the hospital emergency department (ED) has developed as an efficient method to determine the level of urgency and provide appropriate care and treatment. The triage process has been found to be less effective for patients presenting with mental health related problems. Triage guidelines specifically tailored for mental health needs have been introduced in the attempt to overcome existing problems, however, the effectiveness of these guidelines has not been extensively tested. This paper presents the findings of a study conducted in a large metropolitan hospital in Melbourne, Australia. All presentations to the ED for psychiatric problems (n = 137) were triaged using the mental health guidelines over a 3-month period. The same presentations were triaged by psychiatric nurse consultants employed in the ED and the results compared. The results indicate a high level of difference in the triage ranking by the two groups of nurses, with emergency nurses tending to classify presentations as more urgent than their psychiatric nurse colleagues. These findings suggest that mental health education for emergency nurses is necessary if the guidelines are to be used effectively and improve outcomes for patients presenting with psychiatric problems.

Human BIN3 complements the F-actin localization defects caused by loss of Hob3p, the fission yeast homolog of Rvs161p

The BAR adaptor proteins encoded by the RVS167 and RVS161 genes from Saccharomyces cerevisiae form a complex that regulates actin, endocytosis, and viability following starvation or osmotic stress. In this study, we identified a human homolog of RVS161, termed BIN3 (bridging integrator-3), and a Schizosaccharomyces pombe homolog of RVS161, termed hob3+ (homolog of Bin3). In human tissues, the BIN3 gene was expressed ubiquitously except for brain. S. pombe cells lacking Hob3p were often multinucleate and characterized by increased amounts of calcofluor-stained material and mislocalized F-actin. For example, while wild-type cells localized F-actin to cell ends during interphase, hob3Delta mutants had F-actin patches distributed randomly around the cell. In addition, medial F-actin rings were rarely found in hob3Delta mutants. Notably, in contrast to S. cerevisiae rvs161Delta mutants, hob3Delta mutants showed no measurable defects in endocytosis or response to osmotic stress, yet hob3+ complemented the osmosensitivity of a rvs161Delta mutant. BIN3 failed to rescue the osmosensitivity of rvs161Delta, but the actin localization defects of hob3Delta mutants were completely rescued by BIN3 and partially rescued by RVS161. These findings suggest that hob3+ and BIN3 regulate F-actin localization, like RVS161, but that other roles for this gene have diverged somewhat during evolution.

Vancomycin-resistant Enterococcus faecium osteomyelitis: successful treatment with quinupristin-dalfopristin

Vancomycin-resistant enterococci (VRE) have recently emerged as an increasing concern in the management of severe infections. Treatment of these life-threatening infections has been limited to quinupristin-dalfopristin and, more recently, linezolid therapy. We report the first case, to our knowledge, of vancomycin-resistant Enterococcus faecium vertebral osteomyelitis treated successfully with quinupristin-dalfopristin. We review the recent epidemiology of VRE and briefly outline the pharmacology and pharmacokinetics of quinupristin-dalfopristin.

Regulation of vasoactive intestinal peptide receptor expression in developing nervous systems

Vasoactive intestinal peptide (VIP) is a 28-amino acid peptide that has several functions, including the regulation of water and electrolyte secretion, hormone and cytokine release, bronchodilitation, and neurogenesis. VIP effects are mediated by specific G-protein coupled receptors. Three distinct receptor subtypes, with differing affinity for VIP, have been cloned and characterized as receptors 1 and 2 (VPAC1 and VPAC2) and pituitary adenylate cyclase activating polypeptide receptor (PAC1). Our laboratory has demonstrated that upregulation of VPAC1 in SK-N-SH neuroblastoma cells results in marked shift in cell type to the glial lineage with a corresponding loss of neuronal lineage and suppression of xenograft tumor growth. To understand the molecular mechanisms responsible for regulation of the VPAC1 gene in neuronal lineage, we have cloned and sequenced 2.6-kb of the 5'-flanking sequences of the human VPAC1 gene. Sequence analysis demonstrated that the human VPAC1 promoter sequence contains putative binding sites for several known transcription factors, including Sp1, NFkB, and cETS-1. To study the temporal and spatial expression pattern of human VPAC1 promoter sequences, we have generated transgenic mice expressing the bacterial beta-galactosidase gene under the control of the 2.6-kb 5'-flanking and promoter sequence of the human VPAC1 gene. Transgene expression was detected in brain, spinal cord, and lung in 14-day-old animals. Taken together, these results demonstrate that VPAC1 may play an important role in the nervous system, and suggest a role for VIP in neuronal differentiation.

Facilitating comparisons between evaluations of case management programs

We need to know if, as an overall approach to service delivery, case management is delivering on its promises of improving quality, decreasing costs, and increasing access to services. Attempts to do this are hindered by the very limited comparability currently possible between evaluations of case management programs. One cause of this limited comparability is that few individual evaluation reports provide clear and explicit information on key aspects of the evaluation, and on the case management program itself. Consequently, there is a need to ensure that the key characteristics of individual case management programs and their evaluations are clearly described when the results are reported. As a first step in achieving this, a review of the evaluation theory literature and the case management literature was undertaken to find effective ways of describing the differences in evaluations and in case management programs. The result is a draft framework to support the acknowledgment, identification, and description of these differences.

Fluorescence in-situ hybridization analysis of chromosomal constitution in spermatozoa from a mosaic 47,XYY/46,XY male

Sex-chromosome mosaicism in spermatozoa from a mosaic 47,XYY[20%]/46, XY[80%] male with fertility problems was assessed using triple-probe fluorescence in-situ hybridization (FISH) studies. Chromosome-specific probes for X, Y and 18 were used, and the possible outcomes were deduced. In normal haploid spermatozoa of the patient and a normal 46,XY male control, the X:Y ratio was close to 1:1. There was a significant difference in the total incidence of karyotypically abnormal spermatozoa between the patient and the 46, XY male control (2.31% versus 1.46%, P < 0.0001). The incidence of some types of disomic spermatozoa X+Y+18 (24,XY) and X+18+18 (24,X, +18), or diploid X+Y+18+18 (46,XY) spermatozoa was significantly increased in the patient's semen sample. There was, however, no significant difference in the incidence of disomic Y+Y+18 (24,YY) spermatozoa. Because the majority of the patient's spermatozoa was karyotypically normal, the aetiology of his fertility problems was unclear. These results add to the growing body of information regarding chromosome abnormalities in spermatozoa from men who are mosaic for sex chromosome abnormalities. In these men, FISH analysis of spermatozoa may be warranted to determine the relative percentages of abnormal cells, and to determine if in-vitro fertilization with preimplantation genetic diagnosis may increase the likelihood of a successful pregnancy.

Synergistic antitumour activity of vitamins C and K3 against human prostate carcinoma cell lines

Vitamins C, K3 (VC, VK3) and a VC/VK3 combination with a VC:VK3 ratio of 100:1 were assayed for their antitumour activity against two human prostatic carcinoma cell lines. Co-administration of the vitamins enhanced the antitumour activity 5- to 20-fold even with a 1 h exposure time. While exogenous catalase destroyed the antitumour activity, hydrogen peroxide-induced lipid peroxidation was negligible. Analysis of cellular ATP and thiol levels as well as DNA and protein synthesis revealed: a transient increase in ATP production, a decrease in DNA synthesis, an increase in protein synthesis and a decrease in thiol levels. These results suggested that the increased cytotoxicity of the vitamin combination was due to redox cycling and increased oxidative stress.

Synergistic antitumor activity of vitamins C and K3 on human urologic tumor cell lines

A micro-tetrazolium assay was employed to evaluate vitamin C (VC), vitamin K3 (VK3) and vitamin C/vitamin K3 combinations (VC/VK3) for their antitumor activity against eight human urologic tumor cell lines. While the individual vitamins exhibited antitumor activity at high concentrations, co-administration of the vitamins in a VC : VK3 ratio of 100 : 1 potentiated antitumor activity 4- to 61-fold even when exposure times were as short as 1 hour. Administration of exogenous catalase destroyed the antitumor activity of the vitamins and suggested that hydrogen peroxide and perhaps other reactive oxygen species were involved in the antitumor mechanism of these vitamins. Electron micrographs taken in a previous study demonstrated that vitamin treatment damaged mitochondria and may have impaired ATP synthesis. Analysis of cellular ATP and thiol levels as well as DNA and protein synthesis during the first five hours following a one hour VC/VK3 treatment, revealed: a transient increase in ATP production, a substantial decrease in DNA synthesis, an increase in protein synthesis and a decrease in thiol levels. These results suggested that redox cycling of the vitamin combination increased oxidative stress until it surpassed the reducing ability of the cellular thiols and cellular or genetic damage ensued.

Characterization of vasoactive intestinal peptide receptors on human megakaryocytes and platelets

Vasoactive intestinal peptide receptor I (VIPRI) expression was examined in megakaryocytes using reverse transcriptase-polymerase chain reaction (RT-PCR). VIPRI protein was characterized in platelet membranes using covalent crosslinking techniques. Human megakaryocytes were isolated from suspension cultures of cord blood and adult bone marrow mononuclear cells using a murine monoclonal antibody to human platelet glycoprotein IIB/IIIA (CD41) and immunomagnetic beads. RT-PCR primers were constructed for the VIP, VIPRI, and VIPRII genes as well as for megakaryocyte specific genes, c-mpl and platelet factor 4 (PF-4). VIP, VIPRI, c-mpl, and PF-4 were coexpressed in megakaryocyte mRNA. Southern blot analysis confirmed the expression of VIPRI. 125I-VIP was covalently cross-linked to human platelet membranes using the homobifunctional reagent disuccinimidyl suberate, followed by polyacrylamide gel electrophoresis and autoradiography. A 125I-VIP-protein complex of Mr = 50,000 was identified. Labeling of the Mr = 50,000 component was completely abolished by unlabeled VIP, but not by peptide histidine methionine or growth hormone releasing factor, indicating specific binding of VIP to the platelet membranes. Taken together, these results suggest that VIP may have direct effects on megakaryocytopoiesis and support our earlier observations of VIP modulation of platelet aggregation.

Gangliosides inhibit platelet-derived growth factor-stimulated growth, receptor phosphorylation, and dimerization in neuroblastoma SH-SY5Y cells

SH-SY5Y is a thrice cloned cell line originally derived from the human neuroblastoma cell line SK-N-SH. It grows well in serum-containing medium and undergoes neuritogenesis in response to several trophic factors. Because it has been reported that this clonal line does not have receptors for platelet-derived growth factor (PDGF), it has been unclear what the major mitogenic factor in serum is for these cells. In competitive binding studies using radiolabeled PDGF-BB, we found that SH-SY5Y cells specifically bind PDGF with a KD = 0.14 +/- 0.06 nM and Bmax = 7.3 +/- 2.3 pM. Functionality of these receptors was demonstrated by an increased [3H]-thymidine incorporation in response to PDGF (stimulation index = 2.5). At concentrations of PDGF-BB between 5 and 100 ng/ml, maximum stimulation occurred with 20 ng/ml. Maximum DNA synthesis occurred after 12-24-h exposure to PDGF. Gangliosides GM3 and GT1b greatly inhibited [3H]thymidine incorporation, which was also inhibited to a lesser extent by GM1. Phosphorylation on tyrosine of a 170-kDa protein in response to PDGF stimulation of intact cells was demonstrated by western blot analysis probing with anti-phosphotyrosine antibody. Immunoprecipitation with anti-PDGF beta-receptor antibody and visualization on a western blot with an anti-phosphotyrosine antibody also revealed a 170-kDa protein. Maximum phosphorylation of the 170-kDa protein occurred after 5-min exposure to 20 ng/ml PDGF. This phosphorylation was inhibited by gangliosides GM1, GM2, GD1a, and GT1b but not by GM3. Receptor dimerization was also inhibited by GM1. These results show that SH-SY5Y cells have specific receptors for PDGF-BB that are functional, and can be modulated by gangliosides.

Cellular energy metabolism and regulation

Consistent with the increased demand for nutrients imposed by lactation and growth, those tissues directly involved in the digestion, absorption, and processing of the required additional nutrients show response to these states. During lactation, the rumen, upper intestine, and liver increase in size, and more energy is spent on Na+,K+ transport and on protein turnover. The massive endocrine influences during lactation suggest that the metabolism of other tissues besides these and mammary tissue would be influenced, but evidence is rather sparse. Ion transport and protein metabolism in some muscles may indeed be increased. Although substrate cycles characteristically account for a substantially smaller portion of the energy expenditure in the intact animal than do ion transport and protein turnover, stage of lactation influences some of these cycles, particularly the triacylglycerol fatty acid cycle. The needs for additional quantitative in vivo measurements of metabolic conversions and for mechanistic model description of metabolic events in nonmammary tissues are discussed.

Simulation of the energy costs associated with protein turnover and Na+,K+-transport in growing lambs

A mathematical representation of the energy-requiring processes of protein turnover and Na+,K+-transport in the tissues of growing lambs is described. This model was then used to examine the relative contributions of these processes to ATP expenditure at two different growth rates (90-230 g/d). Protein turnover accounted for 19% of whole-body ATP expenditure at both growth rates examined, with the gastrointestinal tract (GIT), accounting for 25-27%, muscle for 21-26%, skin for 23-26% and liver for 13% of total protein turnover energy costs. The contribution of Na+,K+-transport increased from 18 to 23% of whole-body heat production as growth rate increased, with the GIT accounting for 39 and 50%, muscle for 17 and 10% and liver for 18 and 23% of total Na+,K+-transport costs at low and high nutrient inputs, respectively. Thus, protein turnover accounted for 19% of the increment in ATP expenditure due to the increased nutrient input at the higher rate of growth, while Na+,K+-transport accounted for 39%, and fat turnover and accretion accounted for 25%, leaving 17% of the ATP increment unaccounted for.

Mathematical integration of protein metabolism in growing lambs

A mathematical integration of whole-body protein synthesis and degradation based on protein metabolism in 10 individual tissues in growing lambs is described. The tissues represented are adipose, central nervous system (CNS), gastrointestinal tract (GIT), heart, kidney, liver, muscle, pancreatic and salivary glands (PSG), reticuloendothelial system (RES) and skin, together with a blood pool of amino acids. The fluxes represented in the equations are generally assumed to follow simple or modified mass-action kinetics. The fractional rates for protein synthesis in each tissue were calculated from published values for lambs, where these were available, or alternatively derived using assumptions based on data obtained with rats. The initial protein content of each tissue and the fractional degradation rate were assigned values calculated using data from a slaughter experiment. The model was used to examine whole-body protein synthesis at different rates of growth and to compare the relative contributions of each tissue. The GIT (25-26%) and skin (23-26%) had the highest contributions to total protein synthesis, followed by muscle (21-26%), liver (13-14%), RES (6-7%) and PSG (3-6%), while adipose, CNS, heart and kidney together contributed less than 5%. These values agree reasonably well with experimental values, and thus the model can be used to examine the effect of different growth rates on protein metabolism and its associated energy costs.

Structure-activity studies of human IL-1 beta with mature and truncated proteins expressed in Escherichia coli

IL-1 beta is synthesized as an inactive 31-kDa intracellular protein, which is then processed upon secretion to an active 17-kDa carboxyl-terminal fragment. To identify the minimal portion of IL-1 beta required for activity, we constructed several deletion mutants of mature IL-1 beta. These included three amino-terminal deletions of 10, 16, and 81 amino acids, two carboxyl-terminal deletions of 17 and 72 amino acids, and one internal fragment between amino acids 17 and 81. Expression of the mutants was monitored by Western blots and immunoprecipitation. With one exception, all of these mutants and the full length 17-kDa IL-1 beta were expressed as soluble protein in Escherichia coli and could be assayed for activity and receptor binding in lysates without further purification. Whereas the intact 17-kDa IL-1 beta retained full biologic activity (greater than 10(7) U/ml of lysate) and competed for binding with 125I-labeled IL-1 beta, none of the lysates containing IL-1 beta deletion mutant proteins had activity or competed for binding to receptor at significantly higher concentrations. The loss of function in the smallest C-terminal deletion mutant does not appear to be due to the direct involvement of these C-terminal residues in receptor binding because both monoclonal and polyclonal antisera directed to this region bind to IL-1 beta but do not neutralize its activity. Therefore, this region is probably indirectly involved in sustaining the structure of the receptor-binding site.

Structure-activity studies of human IL-1 beta with mature and truncated proteins expressed in Escherichia coli

IL-1 beta is synthesized as an inactive 31-kDa intracellular protein, which is then processed upon secretion to an active 17-kDa carboxyl-terminal fragment. To identify the minimal portion of IL-1 beta required for activity, we constructed several deletion mutants of mature IL-1 beta. These included three amino-terminal deletions of 10, 16, and 81 amino acids, two carboxyl-terminal deletions of 17 and 72 amino acids, and one internal fragment between amino acids 17 and 81. Expression of the mutants was monitored by Western blots and immunoprecipitation. With one exception, all of these mutants and the full length 17-kDa IL-1 beta were expressed as soluble protein in Escherichia coli and could be assayed for activity and receptor binding in lysates without further purification. Whereas the intact 17-kDa IL-1 beta retained full biologic activity (greater than 10(7) U/ml of lysate) and competed for binding with 125I-labeled IL-1 beta, none of the lysates containing IL-1 beta deletion mutant proteins had activity or competed for binding to receptor at significantly higher concentrations. The loss of function in the smallest C-terminal deletion mutant does not appear to be due to the direct involvement of these C-terminal residues in receptor binding because both monoclonal and polyclonal antisera directed to this region bind to IL-1 beta but do not neutralize its activity. Therefore, this region is probably indirectly involved in sustaining the structure of the receptor-binding site.

Autographa californica nuclear polyhedrosis virus efficiently enters but does not replicate in poikilothermic vertebrate cells

The host range of the insect virus Autographa californica nuclear polyhedrosis virus (AcMNPV) was examined. AcMNPV could not initiate a productive infection in frog, turtle, trout, or codling moth cell lines. After exposure to AcMNPV, neither viral DNA nor RNA synthesis could be detected in these cell lines as assayed by nucleic acid probe hybridization. Entry of AcMNPV nucleocapsids into the cytoplasm and viral DNA into the nucleus, however, was as efficient in the nonpermissive cell lines as it was in a permissive insect cell line. The data suggest that the block in AcMNPV infection in these nonpermissive cell lines is at a stage subsequent to viral DNA entry into the nucleus.

Ferritin synthesis in lymphocytes, polymorphs and monocytes

A rapid two-stage method has been devised for the separation of different leucocyte populations from human blood. Different cell types can be obtained in an undamaged state and with little contamination. Ferritin and total protein synthesis has been determined by measuring [14C]leucine incorporation in culture media which contain varying amounts of added ferric iron or desferrioxamine. Both ferritin and total protein synthesis is greater in monocytes than in lymphocytes or polymorphs when the basal medium is used. Only monocytes show a consistent increase in ferritin production due to iron stimulation. Ferritin synthesis by monocytes, polymorphs and lymphocytes is inhibited in the presence of desferrioxamine.