Sorption and desorption behavior of four antibiotics at concentrations simulating wastewater reuse in agricultural and forested soils

Due to rises in antibiotic resistance, fate and transport of antibiotics in soil systems requires greater understanding to determine potential risks to human and animal health. Adsorption coefficients (K_d and K_f) are standard measures for determining sorption capacity and partitioning behavior of organic contaminants in solid matrices. Frequently, sorption studies use higher antibiotic concentrations (mg L^-1) and larger spiked water volume to mass of soil (>5:1), which may not reflect sorption behaviors of antibiotics at low concentrations (ng L^-1 - μg L^-1) in natural soils. The aim of this study was to determine sorption and desorption behaviors of four antibiotics commonly found in soils due to wastewater reuse using parameters replicating typical soil conditions. Concentrations (μg L^-1) of sulfamethoxazole (SMX), trimethoprim (TMP), lincomycin (LIN) and ofloxacin (OFL) were equilibrated with four soil types at a 2:1 ratio of spiked water volume to mass of soil, which better represents field conditions. Log K_f and log K_foc value ranges in this study were 1.88-1.95 and 3.2-4.7 for TMP, 0.43-1.4 and 2.7-3.2 for SMX, and 0.65-1.4 and 2.0-4.1 for LIN, respectively. Ofloxacin adsorbed tightly to soil particles, and adsorption coefficients could not be calculated. Sorption values were higher than previous studies that used similar soil types but had higher ratios of spiking solution to mass of soil (>5:1). Overall, OFL and TMP are expected to strongly interact with soil particles and be less mobile, while SMX and LIN are expected to be more mobile due to weaker sorption interactions.

Less information results in better midsession reversal accuracy by pigeons

The midsession reversal task involves a simultaneous discrimination between Stimulus 1 (S1) and Stimulus 2 (S2) in which, for the first half of each session, choice of S1 is reinforced and S2 is not, and for the last half of each session, choice of S2 is reinforced and S1 is not. With this task, even after considerable training, pigeons tend to make anticipatory errors as they approach the reversal and they continue to make perseverative errors following the reversal. In the present research, we tested the hypothesis that reversal accuracy would improve by devaluing choice of S2 relative to S1. In Experiment 1, correct choice of S1 was reinforced 100% of the time, whereas correct choice of S2 was reinforced only 20% of the time. This manipulation reduced anticipatory errors but did not increase perseverative errors. In Experiment 2, choice of S1 required a single peck, whereas choice of S2 was devalued by requiring 10 pecks. A similar result was found. In Experiment 3 we devalued S1 by requiring 10 pecks and found decreased accuracy in the form of increased anticipatory errors. Paradoxically, in Experiments 1 and 2, by encouraging the pigeons to avoid using the feedback from choice of S2, and rely solely on feedback from choice of S1, discrimination reversal errors were reduced. The results have implications for attentional theories of learning and theories of behavior change. They also have implications for the conditions responsible for pigeons' tendency to time the occurrence of the change in reinforcement contingencies. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Sameness May Be a Natural Concept That Does Not Require Learning

It has been assumed that when pigeons learn how to match to sample, they learn simple stimulus-response chains but not the concept of sameness. However, transfer to novel stimuli has been influenced by pigeons' tendency to be neophobic. We trained pigeons on matching ( n = 7) and mismatching ( n = 8) with colors as samples and, with each sample, one color as the nonmatching comparison. We then replaced either the matching or the nonmatching stimulus with a familiar stimulus never presented with that sample. Results suggest that for both matching and mismatching, pigeons locate the stimulus that matches the sample: If the task involves matching, they chose it; if it involves mismatching, they avoid it. Thus, the concept of sameness is the basis for correct choice with both tasks. This finding suggests that sameness is a basic concept that does not have to be learned and may have evolved in many species, including humans.

Prior commitment: Its effect on suboptimal choice in a gambling-like task

Animals choose suboptimally when provided with cues that signal whether reinforcement is coming or not. For example, pigeons do not prefer an alternative that always provides them with a signal for reinforcement over an alternative that provides them with a signal for reinforcement only half of the time and a signal for the absence of reinforcement the rest of the time. In the present research, we tested the hypothesis that if the results of the choice are delayed, pigeons will choose less suboptimally. We tested this hypothesis by forcing pigeons to wait following their choice, requiring them to complete a fixed-interval 20-s schedule prior to receiving the signals for reinforcement. In Experiment 1, we gave the pigeons a choice between (a) a 50% chance of receiving a signal for reinforcement or a 50% chance of receiving a signal for the absence of reinforcement and (b) a 100% chance of receiving a signal for reinforcement. When the signal for reinforcement was delayed, most of the pigeons chose optimally. When it was not delayed, most of the pigeons chose suboptimally. In Experiment 2, we gave the pigeons a choice between (a) a 25% chance of receiving a signal for reinforcement or a 75% chance of receiving a signal for nonreinforcement and (b) a 100% chance of receiving an unreliable signal for reinforcement (predicting reinforcement 75% of the time). When the signal was not delayed, the pigeons showed a strong tendency to choose suboptimally but they chose suboptimally much less when the signal was delayed.

Uptake of Three Antibiotics and an Antiepileptic Drug by Wheat Crops Spray Irrigated with Wastewater Treatment Plant Effluent

With rising demands on water supplies necessitating water reuse, wastewater treatment plant (WWTP) effluent is often used to irrigate agricultural lands. Emerging contaminants, like pharmaceuticals and personal care products (PPCPs), are frequently found in effluent due to limited removal during WWTP processes. Concern has arisen about the environmental fate of PPCPs, especially regarding plant uptake. The aim of this study was to analyze uptake of sulfamethoxazole, trimethoprim, ofloxacin, and carbamazepine in wheat ( L.) plants that were spray-irrigated with WWTP effluent. Wheat was collected before and during harvest, and plants were divided into grain and straw. Subsamples were rinsed with methanol to remove compounds adhering to surfaces. All plant tissues underwent liquid-solid extraction, solid-phase extraction cleanup, and liquid chromatography-tandem mass spectrometry analysis. Residues of each compound were present on most plant surfaces. Ofloxacin was found throughout the plant, with higher concentrations in the straw (10.2 ± 7.05 ng g) and lower concentrations in the grain (2.28 ± 0.89 ng g). Trimethoprim was found only on grain or straw surfaces, whereas carbamazepine and sulfamethoxazole were concentrated within the grain (1.88 ± 2.11 and 0.64 ± 0.37 ng g, respectively). These findings demonstrate that PPCPs can be taken up into wheat plants and adhere to plant surfaces when WWTP effluent is spray-irrigated. The presence of PPCPs within and on the surfaces of plants used as food sources raises the question of potential health risks for humans and animals.

Vadose Zone Transport of Natural and Synthetic Estrogen Hormones at Penn State's "Living Filter" Wastewater Irrigation Site

The increase in endocrine-disrupting compounds in the environment has generated research focused on the behavior of these compounds in natural soil and water ecosystems. To understand how estrogens behave in the soil environment as a result of 25+ yr of wastewater irrigation, soils from Penn State's "Living Filter" wastewater irrigation site were extracted and analyzed for two natural estrogens (17β-estradiol and estrone) and one synthetic estrogen (17α-ethynylestradiol). Soil estrogen concentrations were compared for two independent variables: type of land cover and sampling time. Soils were sampled from cropped and forested land areas, and soils were sampled 2 d and 3 wk after a single 12-h effluent irrigation event. A nonirrigated control site was sampled to provide natural background data. For 17β-estradiol, the nonirrigated mean concentration was 0.68 ± 0.11 ng cm, and the irrigated values, including samples from both land areas and time frames, ranged from 0.99 ± 0.11 to 1.82 ± 0.69 ng cm. For estrone, the nonirrigated mean concentration was 2.36 ± 0.22 ng cm, and the irrigated values, including samples from both land areas collected and time frames, ranged from 2.18 ± 0.20 to 6.24 ± 3.14 ng cm. The 17α-ethynylestradiol nonirrigated mean concentration was 0.47 ± 0.40 ng cm. The irrigated values, including samples from both land areas and time frames, ranged from 0.25 ± 0.06 to 1.37 ± 0.39 ng cm. This study found that time of sampling, land cover, and irrigation can affect estrogen concentrations in soils, resulting in levels that exceed natural background and require improvements in management practices.

Lupus vasculopathy: Diagnostic, pathogenetic and therapeutic considerations

A rare form of vascular disease in systemic lupus erythematosus (SLE), lupus vasculopathy is characterized by necrosis and accumulation of immunoglobulins (IGs) and complements in the wall of arterioles and small arteries resulting in luminal narrowing. Lupus vasculopathy often accompanies lupus nephritis and portends a poor prognosis. Although there is general agreement on the treatment of lupus nephritis, effective treatment strategies for lupus vasculopathy remain to be defined. We report a 20-year-old woman with SLE who presented with generalized tonic-clonic seizure. Her immunosuppressive regimen consisted of mycophenolate mofetil, prednisone and hydroxychloroquine. On physical examination, she was Cushingoid in appearance and hypertensive. Laboratory tests indicated renal disease. Coagulation studies disclosed de novo lupus anticoagulant. Magnetic resonance imaging of the brain demonstrated acute focal cerebral hemorrhage. Echocardiography revealed reduced ejection fraction and severe mitral regurgitation. Despite high-dose glucocorticoids and mycophenolate mofetil, renal function remained poor. Kidney biopsy demonstrated lupus vasculopathy and glomerulonephritis. Plasma exchange therapy and intravenous cyclophosphamide were administered. Over the ensuing four weeks, renal function improved, complement levels increased, autoantibody titers decreased and lupus anticoagulant disappeared. In conclusion, lupus vasculopathy can occur in SLE despite a heavy immunosuppressive regimen. Antiphospholipid antibodies might be involved in the pathogenesis of lupus vasculopathy. Plasma exchange therapy in conjunction with intravenous cyclophosphamide may represent an effective treatment strategy for lupus vasculopathy.

The thickness, composition and structure of some lipid bilayers and natural membranes

It has been shown that the capacitance, thickness and composition of black lipid films may depend strongly on the hydrocarbon solvent used in their formation. By the use of n-hexadecane, films have been formed which contain effectively no solvent and which are comparable to the leaflets of the mesomorphic phase of the pure lipid. These films have capacitances of ca. 0.6 μF/cm(2) and hydrocarbon thicknesses of ca. 31 Å. Thinner black films of higher capacitances are also described.The capacitances of biological membranes are, in contrast, nearer to 1 μF/cm(2), and it is suggested that the hydrocarbon region in these membranes may often be thinner than in the lipid leaflets. This suggestion is consistent with some X-ray and lipid composition data. It is pointed out that if the membranes contain abnormally thin lipid leaflets, the area per polar head group of the phospholipid must be increased, and that hydrocarbon is thereby exposed to the aqueous phases. Non-polar protein residues could then interact with these hydrocarbon areas, thus tending to stabilize the expanded leaflet.

Determining the minimum sampling rate needed to accurately quantify cumulative spine loading from digitized video

Cumulative low back loads have been linked to the reporting of low back pain. Traditional video-based methods used to estimate these loads are time intensive for data collection and analysis. Sampling less frequently would help to reduce the associated time and cost of this type of approach. The purpose of this study was to determine how the error in estimated cumulative low back loads is affected by reducing video sampling rate. Ten healthy male university students performed three laboratory, sagittal plane lifts of varying mass (2.3, 8.8, and 15.9 kg), speed (0.2, 0.4, 0.8 m/s), and postural demand (lift from floor to table; lower from shelf to table; lift from floor over barrier and lower to floor) while being videotaped (60 frames/s). Digitized body coordinates and anthropometrics were input into a static biomechanical model, resulting in estimates of low back compression and shear forces, and moment. Load-time histories for each condition underwent rectangular integration at 60 (gold standard), 30, 20, 15, 12, 10, 6, 5, 4, 3, 2 and 1 frames/s, resulting in estimates of low back cumulative loads. Mean relative errors with respect to 60 frames/s for all cumulative loads and all conditions were found to be below 8% at 1 frame/s, and less than 3% at 2 frames/s. In addition, analyses at sampling rates above 3 frames/s were not significantly different than the cumulative loads determined at 60 frames/s, for all conditions. The accuracy of cumulative loads exhibited even at low sampling rates can be attributed, in part, to the fact that overestimations and underestimations of the integrated loads tend to cancel out over the length of the tasks considered.

Function of CMV-encoded MHC class I homologues

Homologues of MHC class I proteins have been identified in the genomes of human, murine and rat cytomegaloviruses (CMVs). Given the pivotal role of the MHC class I protein in cellular immunity, it has been postulated that the viral homologues subvert the normal antiviral immune response of the host, thus promoting virus replication and dissemination in an otherwise hostile environment. This review focuses on recent studies of the CMV MHC class I homologues at the molecular, cellular and whole animal level and presents current hypotheses for their roles in the CMV life cycle.

Infection of dendritic cells by murine cytomegalovirus induces functional paralysis

Cytomegalovirus (CMV), measles and HIV are the main human pathogens known to induce immunosuppression. Unlike measles and HIV, and despite the availability of a well studied animal model, little is known about the mechanisms that control CMV-induced immunosuppression. We hypothesized that dendritic cells (DCs), which are crucial in generating and maintaining immune responses, represent a target for CMV and that the transient, but profound, immunosuppression that accompanies CMV infection results from viral interference with DC functions. Here we show that DCs were permissive to murine CMV infection. In addition, DC infection prevented delivery of the signals required for T cell activation. Thus, CMV-mediated impairment of DC function may be crucial for virally induced immunosuppression and interleukin 2 is implicated as a key factor.

A novel autocrine pathway of tumor escape from immune recognition: melanoma cell lines produce a soluble protein that diminishes expression of the gene encoding the melanocyte lineage melan-A/MART-1 antigen through down-modulation of its promoter

We have observed that malignant melanoma cells produce a soluble protein factor(s), which down-regulates melanocyte lineage Melan-A/MART-1 Ag expression by melanoma cells with concomitant loss of recognition by Melan-A/MART-1-specific T cells. This down-modulation of Melan-A/MART-1 expression, which we refer to as "Ag silencing," is mediated via its minimal promoter, whereas the promoter for the restricting Ag-presenting HLA-A2 molecule is not affected. Significantly, this Ag silencing is reversible, as removal of factor-containing supernatants from Melan-A/MART-1-expressing cells results in up-regulation of the promoter for the gene encoding this Ag, and renewed expression of the protein. We have evaluated over 20 known factors, none of which accounts for the Ag-silencing activity of the melanoma cell culture supernatants. The existence of this autocrine pathway provides an additional novel explanation for melanoma tumor progression in vivo in the presence of CTL specific for this melanocyte lineage Ag. These observations may have important implications for Melan-A/MART-1-specific CTL-mediated immunotherapy of melanoma tumors.

An evaluation of predictive methods for estimating cumulative spinal loading

The focus of this study was to assess the amount of error present in several approaches that have been commonly used to estimate the cumulative spinal loading during manual materials handling tasks. Three male subjects performed three sagittal plane lifting tasks of varying loads and postural requirements. Video recordings of the tasks were digitized and a biomechanical model was used to calculate the spinal loading (compression, joint shear, reaction shear, and flexion/extension moment) at L4/L5 for each frame of data. The 'gold standard' for cumulative loading experienced by the subjects was obtained by integrating the resultant biomechanical model outputs for the entire lifting cycle. Five approaches that quantify cumulative spinal loading, four that use discrete measures and one that reduces the number of frames used (5 Hz), were used and compared with the gold standard. The four methods using discrete measures to quantify the cumulative demands of a task resulted in substantial errors (average error across task and subjects was 27-69%). Reducing the number of frames of data processed to 5 frames/s preserved the time varying information and was the only approach examined that did not induce significant error into the cumulative loading estimates. This study indicates that errors in cumulative spinal loading estimates can be large depending upon the approach used, which will hinder any progress in developing a dose-response link between cumulative exposure and an increased risk of low-back pain or injury.

NK1.1+ cells and murine cytomegalovirus infection: what happens in situ?

NK cells mediate early host defense against viral infection. In murine CMV (MCMV) infection NK cells play a critical role in controlling viral replication in target organs, such as spleen and liver. Until now it has not been possible to directly examine the role of NK cells in MCMV-induced inflammation in situ due to the inability to stain specifically for NK cells in infected tissues. In this study, we describe a method of in vivo fixation, resulting in the first identification of NK cells in situ using NK1.1 as the marker. Using this method, we characterize the NK1.1(+) cellular component of the inflammatory response to wild-type MCMV in the spleen, liver, and lung of genetically susceptible and resistant mice following i.p. infection. This study provides the first in situ description of the cellular response mediated specifically by NK cells following MCMV infection.

Outer membrane protein A, peptidoglycan-associated lipoprotein, and murein lipoprotein are released by Escherichia coli bacteria into serum

Complexes containing lipopolysaccharide (LPS) and three outer membrane proteins (OMPs) are released by gram-negative bacteria incubated in human serum and into the circulation in an experimental model of sepsis. The same OMPs are bound by immunoglobulin G (IgG) in the cross-protective antiserum raised to Escherichia coli J5 (anti-J5 IgG). This study was performed to identify the three OMPs. The 35-kDa OMP was identified as outer membrane protein A (OmpA) by immunoblotting studies using OmpA-deficient bacteria and recombinant OmpA protein. The 18-kDa OMP was identified as peptidoglycan-associated lipoprotein (PAL) based on peptide sequences from the purified protein and immunoblotting studies using PAL-deficient bacteria. The 5- to 9-kDa OMP was identified as murein lipoprotein (MLP) based on immunoblotting studies using MLP-deficient bacteria. The studies identify the OMPs released into human serum and into the circulation in an experimental model of sepsis as OmpA, PAL, and MLP.

Melanoma antigen recognition by tumour-infiltrating T lymphocytes (TIL): effect of differential expression of melan-A/MART-1

We have isolated, from an individual patient with metastatic melanoma, a series of eight TIL clones capable of lysing autologous melanoma cell targets. Six of the eight clones expressed TCRAV2S1 and lysed targets expressing HLA-A2 and the Melan-A/MART-1 peptide: AAGIGILTV. Polymerase chain reaction-single stranded conformational polymorphism (PCR-SSCP) analysis showed that the Melan-A/MART-1-specific clones were predominant in the bulk culture prior to cloning. However, the tumour progressed in vivo even in the presence of these tumour cell-lytic clones. Using the anti-Melan-A/MART-1 MoAb (A-103), we noted that Melan-A/MART-1 expression on three melanoma cell lines varied considerably during in vitro culture, in the absence of T cell immunoselection, relative to cell density. Tumour cells which spontaneously decreased Melan-A/MART-1 expression were less susceptible to specific TIL lysis. Melan-A/MART-1 expression and susceptibility to lysis increased in cells cultured at lower density. These data suggest that modulation of tumour antigen may account for tumour progression in the presence of tumour cell-lytic T lymphocytes. The observations suggest a possible explanation for the common finding of Melan-A/MART-1-specific lytic TIL in clinically progressing melanomas, as well as a possible pathway for therapeutic intervention.

Comparison of four peak spinal loading exposure measurement methods and their association with low-back pain

OBJECTIVES

This paper examines the performance of 4 different methods of estimating peak spinal loading and their relationship with the reporting of low-back pain.

METHODS

The data used for this comparison was a subset of subjects from a case-referent study of low-back-pain reporting in the automotive industry, in which 130 random referents and 105 cases (or job-matched proxies) were studied. The peak load on the lumbar spine was determined using a biomechanical model with model inputs coming from a detailed self-report questionnaire, a task-based check list, a video digitization method, and a posture and load sampling technique.

RESULTS

The methods were directly comparable through a common metric of newtons or newton meters of spinal loading in compression, shear, or moment modes. All the methods showed significant and substantial associations with low-back pain in all modes (odds ratios 1.6-2.3). The intraclass correlation coefficients (ICC) showed strong similarities between the checklist and video digitized techniques (ICC 0.84-0.91), moderate similarities between these techniques and the work sampling method (ICC 0.49-0.52), and poor correlations (ICC 0.16-0.40) between the self-report questionnaire and the observer recorded measures.

CONCLUSIONS

While all the methods detected significant odds ratios, they cannot all be used interchangeably for risk assessment at the individual level. Peak spinal compression, moment, and shear are important risk factors for low-back pain reporting, no matter which measurement method is used. Questionnaires can be used for large-scale studies. At the individual level a task-based checklist provides biomechanical model inputs at lower cost and equal performance compared with the criterion video digitization system.

The severity of murray valley encephalitis in mice is linked to neutrophil infiltration and inducible nitric oxide synthase activity in the central nervous system

A study of immunopathology in the central nervous system (CNS) during infection with a virulent strain of Murray Valley encephalitis virus (MVE) in weanling Swiss mice following peripheral inoculation is presented. It has previously been shown that virus enters the murine CNS 4 days after peripheral inoculation, spreads to the anterior olfactory nucleus, the pyriform cortex, and the hippocampal formation at 5 days postinfection (p.i.), and then spreads throughout the cerebral cortex, caudate putamen, thalamus, and brain stem between 6 and 9 days p.i. (P. C. McMinn, L. Dalgarno, and R. C. Weir, Virology 220:414-423, 1996). Here we show that the encephalitis which develops in MVE-infected mice from 5 days p.i. is associated with the development of a neutrophil inflammatory response in perivascular regions and in the CNS parenchyma. Infiltration of neutrophils into the CNS was preceded by increased expression of tumor necrosis factor alpha and the neutrophil-attracting chemokine N51/KC within the CNS. Depletion of neutrophils with a cytotoxic monoclonal antibody (RB6-8C5) resulted in prolonged survival and decreased mortality in MVE-infected mice. In addition, neutrophil infiltration and disease onset correlated with expression of the enzyme-inducible nitric oxide synthase (iNOS) within the CNS. Inhibition of iNOS by aminoguanidine resulted in prolonged survival and decreased mortality in MVE-infected mice. This study provides strong support for the hypothesis that Murray Valley encephalitis is primarily an immunopathological disease.

Synthesis and influenza virus sialidase inhibitory activity of analogues of 4-Guanidino-Neu5Ac2en (Zanamivir) modified in the glycerol side-chain

Analogues of 4-Guanidino-Neu5Ac2en (Zanamivir) have been prepared containing carbamate substituents at the 7-hydroxy position. (4S,5R,6R)-5-Acetylamino-6-[1R-[(6-aminohexyl)carbamoyloxy]-2R,3-dihydroxypropyl]-4-guanidino-5,6-dihydro-4H-pyran-2carboxylic acid and (4S,5R,6R)-5-Acetylamino-6-[1R-[heptylcarbamoyloxy]-2R,3-dihydroxypropyl]-4-guanidino-5,6-dihydro4H-pyran2-carboxylic acid were the two analogues possessing activity comparable to Zanamivir, showing potent inhibition of influenza virus sialidases and good antiviral activity in vitro.

Mixed lymphohaemopoietic chimerism and graft-versus-lymphoma effects after non-myeloablative therapy and HLA-mismatched bone-marrow transplantation

BACKGROUND

HLA-mismatched donor bone-marrow transplantation after standard myeloablative conditioning therapy for haematological malignant disorders has been limited by severe graft-versus-host disease (GVHD) and graft failure. We tested a new approach to find out whether lymphohaemopoietic graft-versus-host reactions could occur without excessive GVHD in mixed haemopoietic chimeras produced across HLA barriers with non-myeloablative conditioning.

METHODS

Five patients with refractory non-Hodgkin lymphoma underwent bone-marrow transplantation from haploidentical related donors sharing at least one HLA A, B, or DR allele on the mismatched haplotype. Conditioning included cyclophosphamide and thymic irradiation before transplantation, and antithymocyte globulin before and after transplantation. The only other GVHD prophylaxis was cyclosporin.

FINDINGS

Four of five patients were evaluable and showed engraftment. Mixed haemopoietic chimerism was established, with a predominance of donor lymphoid tissue and varying degrees of myeloid chimerism. Two patients were in GVHD-free states of complete and partial clinical remission at 460 and 103 days after bone-marrow transplantation.

INTERPRETATION

Mixed chimerism can be induced in adult recipients of HLA-mismatched bone-marrow transplantation by a non-myeloablative conditioning regimen. The antilymphoma responses seen in two patients suggest that allogeneic bone-marrow transplantation without myeloablative conditioning might have potent immunotherapeutic benefits.

Oligoclonality of Vdelta1 and Vdelta2 cells in human peripheral blood mononuclear cells: TCR selection is not altered by stimulation with gram-negative bacteria

Despite the enormous potential repertoire of gammadelta T cells, there are several observations which suggest that the expressed gammadelta repertoire in the periphery of normal individuals is often quite restricted. To assess selective expansions among gammadelta T cells from both adult and newborn blood samples, PBMC from 12 normal adults and cord blood from 15 normal newborns were analyzed for TCRDV1 and TCRDV2 junctional diversity by CDR3 size spectratyping and single-strand conformational polymorphism. Although TCRBV usage showed extensive heterogeneity in adults and newborns, both populations often showed CDR3 region restriction for TCRDV1 and TCRDV2. Analysis of the CDR3 spectratype patterns of newborn twins suggested that clonal selection for TCRDV is independent of genetic background. The possible role of Gram-negative bacteria in driving selective responsiveness of gammadelta T cells in PBMCs from adults was examined by in vitro stimulation with Escherichia coli and Pseudomonas aeruginosa. Donors whose TCRDV repertoire was highly clonal in the unstimulated blood cells showed the same predominant clones among the bacteria-stimulated cultures. In individuals whose gammadelta T cells were less restricted, in vitro stimulation did not select for clonality; rather, the TCRDV repertoires were similar before and after bacterial stimulation. Together, these data indicate that gammadelta T cells are often clonally restricted in adults as well as in newborns and suggest that the prominent stimulatory activity of Gram-negative bacteria does not by itself account for the restriction or diversity of the gammadelta T cell repertoire.

Are humans able to voluntarily elicit maximum muscle force?

Previous investigators have used electrical stimulation superimposed on voluntary efforts to show that humans are capable of maximum muscle activation. In the present study this notion was tested using the interpolated twitch technique enhanced by triggered averaging and doublet stimulation of the human biceps brachii. It was found that the decline in extra torque evoked by percutaneous stimulation with increasing levels of voluntary effort was nonlinear and that none of the twelve subjects was able to elicit a voluntary effort large enough to prevent extra torque of elbow flexion. The exponential nature of the declining extra torque indicated that an extrapolated maximum muscle force could be considerably larger than that to which subjects were able to elicit voluntarily.

Malate dehydrogenase and glucose-6-phosphate dehydrogenase, key markers for studying the genetic diversity of Actinobacillus actinomycetemcomitans

Cell-free extracts of strains belonging to the 5 serotypes of A. actinomycetemcomitans were screened for several enzymes. Enzymes representative of the pentose phosphate pathway/hexose monophosphate shunt and the TCA cycle were present. Of these glucose-6-phosphate dehydrogenase (G6PDH) and malate dehydrogenase (MDH) were the most readily detected and stable. MDH and G6PDH retained more than 50% of their activities at alkaline pHs (10-11) for up to 6 h and 3 h at 25 degrees C, respectively, while at pH 6.5, 50% of their activities were lost within 2-3 h. The Km for malate oxidation catalysed by MDH was 5.8 x 10(-4) M while that for glucose-6-phosphate oxidation was 2.0 x 10(-4) M. The pH optima for MDH and G6PDH oxidation activities were 10 and 9.5, respectively. Among the 5 designated serotypes of A. actinomycetemcomitans three groups were delineated by multilocus enzyme electrophoresis using MDH and G6PDH.

Solid-phase synthesis of O-mannosylated peptides: two strategies compared

A comparison of the O-glycosylation of resin-bound assembled peptides with the incorporation of glycosylated amino acids using established chemistry is presented. Fmoc/tert-butyl-based protecting groups were used for the peptidic moieties in conjunction with acetyl sugar protection. Koenigs-Knorr glycosylations were carried out using protected bromomannose derivatives, the acceptor being threonine or serine, either in solution or within a resin-bound peptide. The characterisation of microgram quantities of glycopeptides by the use of glycosidases in combination with mass spectrometry is also described.

Solid-phase synthesis of a range of O-phosphorylated peptides by post-assembly phosphitylation and oxidation

A completely general method for the O-phosphorylation of peptides of any given composition using solid-phase methodology is described. Peptides were assembled using Fmoc amino acid active esters, with base used for Fmoc deprotection. Unprotected amino acid side chain hydroxyl groups were phosphitylated and oxidised at the end of the assembly using bis(benzyloxy)(diisopropylamino)phosphine and tert.-butylhydroperoxide respectively. TFA was used for final deprotection of the amino acid side chains and for simultaneous cleavage from the resin. The synthesis of O-phosphopeptides of up to 15 residues in length is described.

Transient corneal opacification induced by cold in Raynaud's disease

A 48-year-old man presented with longstanding complaints of transient blurring of vision on exposure to cold temperatures. A review of family history was noteworthy in that two of the patient's four sons and the patient's brother had similar complaints. All affected individuals had Raynaud's disease. Results of ophthalmic evaluation showed transient corneal opacities. Slit-lamp video photography under cold stress demonstrated conjunctival vascular changes consistent with Raynaud's phenomenon. An extensive work-up for systemic disease was otherwise negative. To the best of the authors' knowledge, anterior segment changes have not been described previously in idiopathic Raynaud's disease.

Strong association of bovine IgM with microvilli and their microfilament core from 13762 ascites tumor cells

Microfilament cores, obtained by extracting 13762 mammary ascites tumor cell microvilli with Triton X-100, contain a major glycoprotein migrating at an apparent molecular weight of 80 kDa by dodecyl sulfate-polyacrylamide gel electrophoresis. The 80-kDa component is a disulfide-linked multimer, as demonstrated by velocity sedimentation and agarose-acrylamide gel electrophoresis analyses under nonreducing conditions. This 80-kDa species is not metabolically labeled, as is a minor 80-kDa glycoprotein found in the cores, membranes, and an isolated transmembrane complex with actin. Antibodies prepared against the 80-kDa glycoprotein react strongly with bovine IgM and more weakly with rat IgM. These antibodies were used to demonstrate that the 80-kDa component is present in microvilli, microvillar microfilament cores, and microvillar membranes only if the microvilli are prepared in the presence of calf serum. The 80-kDa component, purified by velocity sedimentation in dodecyl sulfate, reacts with anti-rat IgM by immunoblot analyses. Moreover, immunoprecipitation of detergent extracts of microvilli with anti-rat IgM specifically sediments the 80-kDa component. The 80-kDa glycoprotein fractionates with the actin-containing transmembrane complex prepared by gel filtration of Triton-solubilized microvillar membranes. These results indicate that the disulfide-linked, multi-meric 80-kDa component is bovine IgM, which binds strongly to a cell-surface component of the microvilli, and is indirectly associated with the microfilament cores. Thus, the IgM provides a marker by which the transmembrane complexes to the microfilaments can be identified.

Actin-associated cell-surface glycoprotein from ascites cell microvilli: a disulfide-linked multimer

Isolated microvilli of the MAT-C1 subline of the 13762 rat mammary adenocarcinoma contain a transmembrane complex composed of a cell surface, cytoskeleton-associated glycoprotein (CAG), actin, and a 58,000-dalton polypeptide (58K). The behavior of CAG has been studied by differential centrifugation and velocity sedimentation gradient centrifugation of detergent extracts of microvilli. CAG can be pelleted along with a fraction of the microvillar actin even in the presence of ionic detergents and under microfilament-depolymerizing conditions. By velocity sedimentation analysis CAG in Triton/PBS extracts sediments as a large, heterogeneous species (sedimentation coefficient greater than 25S). In Sarkosyl and sodium dodecyl sulfate (SDS) the size and heterogeneity are somewhat reduced. In SDS CAG sediments as a 20S species in the absence of mercaptoethanol and as a 5S species in the presence of mercaptoethanol. These results indicate that CAG is a disulfide-linked multimer in the microvillus membrane. We suggest that the stable multimeric structure of CAG permits it to act as the membrane association site for several microfilaments and plays an important role in the formation and stabilization of the microvillus structure.

Hydrogel implants for refractive keratoplasty: corneal morphology

Refractive keratoplasty procedures for large dioptric corrections utilize a lenticular addition to the cornea which is typically cut from a donor cornea, but can also be fabricated from hydrogel plastics (1). The success of an intrastromal hydrogel implant depends on the nonreactiveness of both the hydrogel to the stroma tissue and the tissue environment to the hydrogel. Permalens hydrogel (Cooper Labs, Inc.) was fabricated into 6 mm diameter, 0.24 mm thick, and +15.00 diopter lenticules and surgically implanted into intracorneal pockets of rabbit corneas for eleven months. Light and electron microscopy revealed scattered zones of abnormal fibroblast activity at the posterior interface of the hydrogel and stroma. The anterior pocket lining was covered with a single cell layer of keratocytes, but there were no irregular areas that might be light scattering. The remaining ultrastructure appeared normal. Preliminary work with primates did not reveal this type of abnormal fibroblast activity. The data indicates that hydrogels for intrastromal implantation in refractive keratoplasty have a promising future.

Refractive keratoplasty with intrastromal hydrogel lenticular implants

The feasibility of using hydrogel lenticular implants of high water content to alter the anterior corneal curvature for purposes of refractive keratoplasty has been investigated in rabbits. Lenticules (6 mm in diameter) of Permalens (Perfilcon-A) were trephined from contact lens and implanted within an intralamellar pocket in the cornea. The in vitro glucose flux across the hydrogel (0.23 mm thick) was measured at 131 +/- 7 micrograms/cm(2)/hr. For clinical comparison, non-water-permeable disks of Teflon were also implanted. The Teflon implant caused an aseptic ulcer to develop anterior and central to the implant by 9 +/- 4 days. The hydrogel lenticular implant did not cause central ulceration during the 7 month postoperative follow-up. There was a thinning and eventual erosion of the stroma anterior to the edge of the hydrogel implant, 16 +/- 7 weeks. The glycogen contents of the epithelium anterior to (1) the sham operation, i.e., lamellar pocket dissection, (2) the implanted hydrogel lenticule with or without the presence of an erosion, and (3) the control corneas were statistically from the same population. Yet there was a slight dehydration of the stroma anterior to the hydrogel implant when compared to control tissue. A thin-edged implant lenticule design should overcome the stromal thinning caused by the thick-edge implants. During the short-term follow-up, the hydrogel lenticular implant proved to be successful as a refractive keratoplasty implant material.