Evaluation of the performance of a lateral flow device for quantitative detection of anti-SARS-CoV-2 IgG

INTRODUCTION

The AbC-19™ lateral flow immunoassay (LFIA) performance was evaluated on plasma samples from a SARS-CoV-2 vaccination cohort, WHO international standards for anti-SARS-CoV-2 IgG (human), individuals ≥2 weeks from infection of RT-PCR confirmed SARS-CoV-2 genetic variants, as well as microorganism serology.

METHODS

Pre-vaccination to three weeks post-booster samples were collected from a cohort of 111 patients (including clinically extremely vulnerable patients) from Northern Ireland. All patients received Oxford-AstraZeneca COVID-19 vaccination for the first and second dose, and Pfizer-BioNTech for the third (first booster). WHO international standards, 15 samples from 2 variants of concern (Delta and Omicron) and cross-reactivity with plasma samples from other microorganism infections were also assessed on AbC-19™.

RESULTS

All 80 (100%) participants sampled post-booster had high positive IgG responses, compared to 38/95 (40%) participants at 6 months post-first vaccination. WHO standard results correlated with information from corresponding biological data sheets, and antibodies to all genetic variants were detected by LFIA. No cross-reactivity was found with exception of one (of five) Dengue virus samples.

CONCLUSION

These findings suggest BNT162b2 booster vaccination enhanced humoral immunity to SARS-CoV-2 from pre-booster levels, and that this antibody response was detectable by the LFIA. In combination with cross-reactivity, standards and genetic variant results would suggest LFIA may be a cost-effective measure to assess SARS-CoV-2 antibody status.

INOCA affects more than the coronaries

Background

Ischaemia with normal coronary arteries (INOCA) may result in disabling symptoms and has an association with adverse long-term prognosis. The diagnosis of INOCA necessitates invasive coronary angiography to perform a physiological evaluation of microvascular function.

The conjunctiva has a readily assessable microvascular network in which physiological parameters can be evaluated. We compared conjunctival haemodynamics in patients with and without coronary microvascular disease (MVD) to assess if systemic microvascular dysfunction was present in this coronary artery disease sub-group.

Methods

In this study, we recruited patients undergoing invasive coronary angiography for the investigation of angina or angina equivalent symptoms. All patients had physiologically insignificant epicardial disease (FFR≥0.80) and underwent a physiological evaluation of coronary microvascular function. We compared a group with evidence of coronary MVD (IMR≥25 or CFR<2.0); to a group of controls without MVD (IMR<25 and CFR≥2.0).

The conjunctival microvasculature was imaged using a previously validated combination of a smartphone and slit-lamp biomicroscope. The conjunctival vasculature was assessed using a semi-automated process of vessel diameter measurement and erythrocyte tracking to obtain haemodynamic parameters of microvascular function.

Results

A total of 111 patients were included (43 MVD and 68 controls). There were no differences in baseline demographics, co-morbidities, epicardial coronary disease severity or regular pharmacological therapies between the groups. Mean coronary flow reserve (CFR) was lower and mean index of microcirculatory resistance (IMR) higher in the MVD cohort (CFR 2.5±1.3 vs 5.2±2.5, p<0.001 and IMR 28.4±11.8 vs 13.7±5.0, p<0.001).

A total of 2295 conjunctival vessels were analysed. The mean number of vessels per patient was 21.0±12.8 (3.2±3.5 arterioles and 14.8±10.8 venules). Significant reductions in axial/cross-sectional velocity, wall shear rate and wall shear stress were observed in the MVD cohort. Table 1 demonstrates a comparison of conjunctival physiological parameters between the groups.

The most marked differences were observed in conjunctival arterioles. Due to the heterogenous size distribution of microvessels, arterioles were categorised into 2 diameter sub-groups (10–25 μm and 25–40 μm) for analysis (Table 2).

Conclusion

The reductions in microvascular blood flow velocity and rate that form the basis for the diagnosis of coronary microvascular dysfunction can be observed non-invasively in the bulbar conjunctiva microcirculation. Conjunctival vascular imaging may have utility as a non-invasive imaging modality to both diagnose microvascular dysfunction and augment conventional cardiovascular risk stratification.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Belfast Trust Heart Trust Fund and Northern Ireland Chest Heart and Stroke

A programmable soft chemo-mechanical actuator exploiting a catalyzed photochemical water-oxidation reaction

We describe a composite hydrogel containing an embedding coupled chemistry for light-sensitized catalytic reactions that enables chemo-mechanical actuation of poly(acrylic acid)-based gels. In these materials, a photosensitizer and catalyst-ruthenium trisbipyridine and iridium dioxide nanoparticles, respectively-are incorporated into the hydrogel where together, with visible light irradiation, they undergo a catalytic water-oxidation reaction that lowers the pH and induces a dissipative/chemically-driven strain change in the gel. To demonstrate the capacity for 3D chemo-mechanical actuation, a layer of non-pH responsive poly(2-hydroxyethyl methacrylate) is added to the photo-active composite gel to create a model bimorph actuator. Triggering and terminating the water-oxidation reaction leads to a programmatic expansion and contraction of the active layer, which induces different modes of biomimetic curling motions in the bimorph actuator in light and dark environments. The efficiency of this system is fundamentally limited by the system-level design, which provides no capacity to sustain a local pH gradient against diffusive mixing. Even so, if the initial pH of the background solution is reestablished either actively or passively between each reaction cycle, it is possible to realize multiple cycles of reversible actuation. We describe a thermodynamic analysis of this system which identifies specific features mediating efficiency losses and conceptual requirements for mesoscopic design rules for optimization of this system and for advancing soft actuation systems in general.

Modular Polymer Biosensors by Solvent Immersion Imprint Lithography

We recently demonstrated Solvent Immersion Imprint Lithography (SIIL), a rapid benchtop microsystem prototyping technique, including polymer functionalization, imprinting and bonding. Here, we focus on the realization of planar polymer sensors using SIIL through simple solvent immersion without imprinting. We describe SIIL's impregnation characteristics, including an inherent mechanism that not only achieves practical doping concentrations, but their unexpected 2-fold enhancement compared to the immersion solution. Subsequently, we developed and characterized optical sensors for detecting molecular O₂. To this end, a substantially high dynamic range is reported, including its control through the immersion duration, a manifestation of SIIL's modularity. Overall, SIIL exhibits the potential of improving the operating characteristics of polymer sensors, while significantly accelerating their prototyping, as it requires a few seconds of processing and no need for substrates or dedicated instrumentation. These are critical for O₂ sensing as probed by way of example here, as well as any polymer permeable reactant.

Infant health effects of a nurse-community health worker home visitation programme: a randomized controlled trial

BACKGROUND

  Home visiting is supported as a way to improve child health and development. Home visiting has been usually provided by nurses or community health workers (CHWs). Few studies compared the child health advantages of a nurse-CHW team approach over nurse prenatal and postnatal home visiting.

METHODS

  A randomized trial was conducted with Medicaid-insured pregnant women in Kent County, Michigan. Pregnant women were assigned to a team intervention including nurse-CHW home visitation, or standard community care (CC) including nurse home visitation. Morbidity was assessed in 530 infants over their first 12 months of life from medical claims and reported by the mother.

RESULTS

  There were no differences in overall child health between the nurse-CHW intervention and the CC arm over the first year of life. There were fewer mother-reported asthma/wheezing/croup diagnostics in the team intervention group among infants whose mothers have low psychosocial resources (13% vs. 27%, P = 0.01; adjusted OR = 0.4, P = 0.01). There were no differences in diagnosed asthma/wheezing/croup documented by medical claims. There were no differences in immunizations, hospitalizations and ear infections.

CONCLUSIONS

  There was no strong evidence that infant health was improved by the addition of CHWs to a programme of CC that included nurse home visitation. Targeting such interventions at common health problems of infancy and childhood or at diagnosed chronic conditions may prove more successful.

Life extension of self-healing polymers with rapidly growing fatigue cracks

Self-healing polymers, based on microencapsulated dicyclopentadiene and Grubbs' catalyst embedded in the polymer matrix, are capable of responding to propagating fatigue cracks by autonomic processes that lead to higher endurance limits and life extension, or even the complete arrest of the crack growth. The amount of fatigue-life extension depends on the relative magnitude of the mechanical kinetics of crack propagation and the chemical kinetics of healing. As the healing kinetics are accelerated, greater fatigue life extension is achieved. The use of wax-protected, recrystallized Grubbs' catalyst leads to a fourfold increase in the rate of polymerization of bulk dicyclopentadiene and extends the fatigue life of a polymer specimen over 30 times longer than a comparable non-healing specimen. The fatigue life of polymers under extremely fast fatigue crack growth can be extended through the incorporation of periodic rest periods, effectively training the self-healing polymeric material to achieve higher endurance limits.

PTTG's C-terminal PXXP motifs modulate critical cellular processes in vitro

Human pituitary tumor-transforming gene (PTTG), known also as securin, is a multifunctional protein implicated in the control of mitosis and the pathogenesis of thyroid, colon, oesophageal and other tumour types. Critical to PTTG function is a C-terminal double PXXP motif, forming a putative SH3-interacting domain and housing the gene's sole reported phosphorylation site. The exact role of phosphorylation and PXXP structure in the modulation of PTTG action in vitro remains poorly understood. We therefore examined the mitotic, transformation, proliferation and transactivation function of the C-terminal PXXP motifs of human PTTG. Live-cell imaging studies using an EGFP-PTTG construct indicated that PTTG's regulation of mitosis is retained regardless of phosphorylation status. Colony-formation assays demonstrated that phosphorylation of PTTG may act as a potent inhibitor of cell transformation. In proliferation assays, NIH-3T3 cells stable transfected and overexpressing mutations preventing PTTG phosphorylation (Phos-) showed significantly increased [3H]thymidine incorporation compared with WT, whereas mutants mimicking constitutive phosphorylation of PTTG (Phos+) exhibited reduced cell proliferation. We demonstrated that PTTG transactivation of FGF-2 in primary thyroid and PTTG-null cell lines was not affected by PTTG phosphorylation but was prevented by a mutant disrupting the PXXP motifs (SH3-). Taken together, our data suggest that PXXP structure and phosphorylation are likely to exert independent and critical influences upon PTTG's diverse actions in vitro.

Disruption of the structure of the Golgi apparatus and the function of the secretory pathway by mutants G93A and G85R of Cu, Zn superoxide dismutase (SOD1) of familial amyotrophic lateral sclerosis

The Golgi apparatus of motor neurons (GA) is fragmented in sporadic amyotrophic lateral sclerosis (ALS), in familial ALS with SOD1 mutations, and in mice that express SOD1G93A of familial ALS, in which it was detected months before paralysis. In paralyzed transgenic mice expressing SOD1G93A or SOD1G85R, mutant proteins aggregated not only in the cytoplasm of motor neurons, but also in astrocytes and oligodendrocytes. Furthermore, aggregation of the G85R protein damaged astrocytes and was associated with rapidly progressing disease. In order to gain insight into the functional state of the fragmented GA, we examined the effects of S0D1 mutants G93A and G85R in Chinese Hamster Ovary Cells (CHO). In contrast to cells expressing the wt and G93A, the G85R expressers had no SOD1 activity. However, cells expressing both mutants, and to a lesser degree the wt, showed decreased survival, fragmentation of the GA, and dysfunction of the secretory pathway, which was assessed by measuring the amount of cell surface co-expressed CD4, a glycoprotein processed through the GA. The G93A and wt proteins were partially recovered in detergent insoluble fractions; while the recovery of G85R was minimal. Both mutants showed equal reductions of cell survival and function of the secretory pathway, in comparison to the wt and cells expressing mutant alsin, a protein found in rare cases of fALS. These results are consistent with the conclusion that the two SOD1 mutants, by an unknown mechanism, promote the dispersion of the GA and the dysfunction of the secretory pathway. This and other in vitro models of mutant SOD1 toxicity may prove useful in the elucidation of pathogenetic mechanisms.

Folding-driven synthesis of oligomers

The biological function of biomacromolecules such as DNA and enzymes depends on their ability to perform and control molecular association, catalysis, self-replication or other chemical processes. In the case of proteins in particular, the dependence of these functions on the three-dimensional protein conformation is long known and has inspired the development of synthetic oligomers and polymers with the capacity to fold in a controlled manner, but it remains challenging to design these so-called 'foldamers' so that they are capable of inducing or controlling chemical processes and interactions. Here we show that the stability gained from folding can be used to control the synthesis of oligomers from short chain segments reversibly ligated through an imine metathesis reaction. That is, folding shifts the ligation equilibrium in favour of conformationally ordered sequences, so that oligomers having the most stable solution structures form preferentially. Crystallization has previously been used to shift an equilibrium in order to indirectly influence the synthesis of small molecules, but the present approach to selectively prepare macromolecules with stable conformations directly connects folding and synthesis, emphasizing molecular function rather than structure in polymer synthesis.

Clinical cytokine network cytometry

Cytokines play an important role in human health and disease. Monitoring their effects and detecting alterations in the complex balance of cytokines within a patient will undoubtedly become increasingly common in the clinical laboratory. Because of the complexity of the network interactions, multiple assays measuring soluble cytokines ("what"), cytokine-producing cells ("who"), surface receptors ("where"), and function (how) simultaneously are necessary to provide clinically useful information. The explosion of reagents and applications for use in the clinical flow cytometry laboratory makes this the perfect setting to perform the multidimensional studies required. Clinical cytokine network cytometry exemplifies the power of multiparameter, high throughput technologies that will change the face of clinical laboratories in the twenty-first century.

An organic self-regulating microfluidic system

In this paper we present an organic feedback scheme that merges microfluidics and responsive materials to address several limitations of current microfluidic systems. By using in situ fabrication and by taking advantage of microscale phenomena (e.g., laminar flow, short diffusion times), we have demonstrated feedback control of the output pH in a completely organic system. The system autonomously regulates an output stream at pH 7 under a range of input flow conditions. A single responsive hydrogel component performs the functionality of traditional feedback system components. Vertically stacked laminar flow is used to improve the time response of the hydrogel actuator. A star shaped orifice is utilized to improve the flow characteristics of the membrane/orifice valve. By changing the chemistry of the hydrogel component, the system can be altered to regulate flow based on hydrogels sensitive to temperature, light, biological/molecular, and others.

Multiparameter flow cytometric approach for simultaneous evaluation of T lymphocyte-endothelial cell interactions

Since vascular endothelium is now recognized as an immunologically active tissue, a better understanding of the relationship between endothelial cells and T lymphocytes is critical to the field of solid organ transplantation. Investigations of endothelial cell-T cell interactions have been limited by methodology. We developed a flow cytometric method allowing for concurrent investigation of multiple cell populations within the same culture that can be applied to these complex interactions. Allogeneic CD8+ or CD4+ T cells labeled with 5,6-carboxyfluorescein diacetate succinimidyl ester (CFSE) were added to a murine endothelial cell monolayer, in which endothelial proliferation was not inhibited by irradiation or addition of a cell cycle-blocking agent. At specific time points, the coculture was analyzed by flow cytometry. T-cell proliferation could be detected by gating on the T-cell subset and evaluating the CFSE fluorescence peaks. By directly analyzing cellular division, we minimized erroneous interpretation of the data encountered by previous studies, which utilized (3)H-thymidine incorporation as sole measure of proliferation. Further subgating on cells that divided facilitated the study of CD8+ lymphocyte activation, differentiation, and acquisition of effector function. By gating on the endothelial cell population, phenotypic changes such as upregulation of surface MHC molecules or immune-mediated apoptosis could be detected. In conclusion, we present a flow cytometric approach that could have important applications for clinical immunological monitoring in allogeneic or xenogeneic transplantation, and might provide the requisite information to better tailor immunotherapy to prevent chronic rejection.

Cooperativity in the folding of helical m-phenylene ethynylene oligomers based upon the 'sergeants-and-soldiers' principle

The 'Sergeants-and-Soldiers' principle has been examined in a series of m-phenylene ethynylene oligomers containing both chiral and achiral side chains. Circular dichroism (CD) spectroscopy was used to examine the twist sense bias of the helical conformation in the polar solvent acetonitrile. A non-linear dependence of the CD signal on the amount of chiral side chains was observed revealing cooperative interactions among the side chains through the backbone. On the other hand, the experiments indicate that in acetonitrile a full bias of the helicity cannot be accomplished by chiral side chains alone. Nevertheless, the folded oligomers are highly ordered since the placement of a single chiral side chain at the beginning of an oligomer results in the induction of a strong twist sense bias into the ordered helical conformation.

Self-assembly of folded m-phenylene ethynylene oligomers into helical columns

Circular dichroism spectroscopy has been used to study the self-assembly of two series of m-phenylene ethynylene oligomers in highly polar solvents. The helical conformation of shorter oligomer lengths was found to be stabilized in aqueous acetonitrile solutions, while longer oligomers began to interact intermolecularly. The intermolecular aggregation of the oligomers in aqueous solutions revealed a chain length dependent association that required the presence of a stable helical conformation. Evidence for intermolecular interactions is provided by Sergeants and Soldiers experiments in which the twist sense bias of a chiral oligomer is transferred to an achiral oligomer.

Dysregulation of lymphocyte interleukin-12 receptor expression in Sézary syndrome

Initial phase I and II clinical trials with recombinant human interleukin-12 have demonstrated the therapeutic efficacy of this cytokine in early stage cutaneous T cell lymphoma as compared with more advanced stages such as the leukemic Sézary syndrome. In an effort to optimize the use of recombinant human interleukin-12, using flow cytometry we studied the regulation of the interleukin-12 receptor beta1 (high affinity chain) and beta2 (chain necessary for interleukin-12 signal transduction) on normal volunteer CD4+ and CD8+ T cells and CD4+ and CD8+ cells from eight patients with different degrees of leukemic involvement with Sézary syndrome. The beta1 chain was not readily detectable on resting normal and T cells from Sézary patients, but expression was induced following T cell activation with phytohemagglutinin. Similarly, the beta2 chain was not detectable on resting normal volunteer T cells, but could be induced following phytohemagglutinin stimulation. Moreover, the beta2 chain on normal volunteer T cells was markedly upregulated following short-term culture with interferon-gamma or recombinant human interleukin-12. CD8+ T cells routinely exhibited a greater expression of beta2 than did CD4+ T cells. In marked contrast, both CD4+ and CD8+ T cells from patients with Sézary syndrome and a high tumor cell burden (> 50% circulating atypical Sézary T cells) failed to express the beta2 chain under any culture conditions. Although, culture with anti-interleukin-10 also markedly increased beta2 expression on normal volunteer T cells, this failed to induce expression on either CD4+ or CD8+ T cells from Sézary patients and a high tumor burden. Investigation of patients with Sézary syndrome and a low tumor cell burden (< 15% circulating Sézary T cells) revealed a pattern of beta2 expression that was intermediate between advanced Sézary syndrome and normal volunteers. Both CD4+ and CD8+ peripheral blood T cells from these earlier stage patients were induced to express the beta2 chain, although at a lower frequency of positivity than T cells from normals, following culture with phytohemagglutinin, interferon-gamma, recombinant human interleukin-12, or anti-interleukin-10. These results indicate that short-term culture with interferon-gamma and recombinant human interleukin-12 potently upregulates beta2 chain expression on T cells from normal volunteers, whereas a similar, but less marked effect occurs on T cells from Sézary syndrome patients and a low circulating tumor cell burden. In contrast, the beta2 chain appears to be suppressed on both CD4+ and CD8+ T cells from Sézary patients with a heavy circulating tumor cell burden and it is not induced by interferon-gamma or recombinant human interleukin-12. Therefore, recombinant human interleukin-12 is likely to be most effective for early stage cutaneous T cell lymphoma due to a greater display of beta2 receptors on responding CD8+ anti-tumor cytotoxic T cells.

Predictive validity of the Strain Index in turkey processing

The Strain Index is a job analysis method for determining if workers are exposed to increased risk of developing distal upper extremity disorders. Its predictive and external validity was initially demonstrated in a pork processing plant. The purpose of this study was to evaluate the predictive validity of the Strain Index in one turkey processing plant. While blinded to health outcomes, investigators analyzed the right and left sides of workers in 28 jobs using the Strain Index and classified them as "hazardous" or "safe" based on the Strain Index score. Subsequently, OSHA 200 logs were used to ascertain the occurrence of distal upper extremity disorders retrospectively. If at least one such disorder had occurred on the right or left side during the previous 3 years, that side was classified as "positive." If no such disorder was reported during the previous 3 years, that side was classified as "negative." When comparing sides, symmetry between morbidity and hazard classification was required. When comparing jobs, such symmetry was not required. Evidence of association between the hazard classifications and the morbidity classifications for the 56 sides and the 28 jobs was evaluated using 2 x 2 contingency tables. For the sides, the association between hazard classification and morbidity classification was statistically significant, with an odds ratio of 22.0. The sensitivity, specificity, positive predictive value, and negative predictive value were 0.86, 0.79, 0.92, and 0.65, respectively. Similar results were noted for the jobs--the odds ratio was 50.0, and the sensitivity, specificity, positive predictive value, and negative predictive value were 0.91, 0.83, 0.95, and 0.71. These results provide additional evidence of the external validity and predictive validity of the Strain Index.

Synergistic growth inhibition of prostate cancer cells by 1 alpha,25 Dihydroxyvitamin D(3) and its 19-nor-hexafluoride analogs in combination with either sodium butyrate or trichostatin A

Prostate cancer is a major cause of male cancer death. In vitro and in vivo data support a role for 1 alpha,25 Dihydroxyvitamin D(3) (1 alpha,25(OH)(2)D(3)) in regulating the growth and differentiation of the normal prostate gland yet prostate cancer cells appear significantly less sensitive to this action. Vitamin D(3) receptor (VDR) content or mutational status do not correlate clearly with the antiproliferative effects of 1 alpha,25(OH)(2)D(3) and therefore it is unclear why prostate cancer cell lines are significantly less sensitive to this action. We hypothesized that the antiproliferative responses of prostate cancer cells to 1 alpha,25(OH)(2)D(3) are suppressed by a process involving histone deacetylation. Sodium butyrate (NaB) and trichostatin A (TSA) are inhibitors of histone deacetylase (HDAC) activity. Low doses of NaB or TSA (300 microM and 15 nM respectively), which alone were relatively inactive, synergized with 1 alpha,25(OH)(2)D(3) in liquid and semi-solid agar to inhibit the growth of LNCaP, PC-3 and DU-145 prostate cancer cells. Still greater synergy was observed between vitamin D(3) hexafluoride analogs and either NaB or TSA. The mechanism appeared to involve neither the cyclin-dependent kinase inhibitor, p21((waf1/cip1)) nor cell cycle arrest, but rather induction of apoptosis. These data suggest that cells dysregulate the normal pro-apoptotic signals of 1 alpha,25(OH)(2)D(3) during prostate cancer development by a mechanism involving histone deacetylation. Combination therapy with potent vitamin D(3) analogs and clinically approved HDAC inhibitors may overcome this lesion and improve the treatment of both androgen-dependent and independent prostate cancer.

HIV infection in women in the United States: status at the Millennium

CONTEXT

During the past decade, knowledge of human immunodeficiency virus (HIV) infection in women has expanded considerably but may not be easily accessible for use in understanding and prioritizing the clinical needs of HIV-infected women.

OBJECTIVES

To perform a comprehensive review of epidemiologic, clinical, psychosocial, and behavioral information about HIV in women, and to recommend an agenda for future activities.

DATA SOURCES

A computerized search, using MEDLINE and AIDSline, of published literature was conducted; journal articles from January 1981 through July 2000 and scientific conference presentations from January 1999 through July 2000 were retrieved and reviewed for content; article reference lists were used to identify additional articles and presentations of interest.

STUDY SELECTION

Data from surveillance and prospective cohort studies with at least 20 HIV-infected women and appropriate comparison groups were preferentially included.

DATA EXTRACTION

Included studies of historical importance and subsequent refined analyses of topics covered therein; these and studies with more current data were given preference. Four studies involving fewer than 20 women were included; 2 studies were of men only.

DATA SYNTHESIS

Women account for an increasing percentage of all acquired immunodeficiency syndrome (AIDS) cases, from 6.7% (1819/27 140 cases) in 1986 to 18% (119 810/724 656 cases) in 1999. By the end of 1998, of all newly reported AIDS cases among women, proportionally more were in the South (41%), among black women (61%), and from heterosexual transmission (38%). Of note, increasingly more women have no identified or reported risk, about half or more of whom are estimated to be infected heterosexually. It is estimated that a total of at least 54% of women newly reported with AIDS in 1998 acquired HIV through heterosexual sex, including women in the no identified or reported risk category estimated to have been infected heterosexually, meeting the surveillance heterosexual risk definition. Natural history, progression, survival, and HIV-associated illnesses-except for those of the reproductive tract-thus far appear to be similar in HIV-infected women and men. Although antiretroviral therapy has proven to be highly effective in improving HIV-related morbidity and mortality rates, women may be less likely than men to use these therapies. Drug use, high-risk sex behaviors, depression, and unmet social needs interfere with women's use of available HIV prevention and treatment resources.

CONCLUSIONS

Continued research on HIV pathogenesis and treatment is needed; however, emphasis should also be placed on using existing knowledge to improve the clinical care of women by enhancing use of available services and including greater use of antiretroviral therapy options, treating depression and drug use, facilitating educational efforts, and providing social support for HIV-infected women.

Validity of generic risk factors and the strain index for predicting nontraumatic distal upper extremity morbidity

Nine individual generic risk factors, eight combinations of generic risk factors, the presence of any generic risk factor, and the Strain Index were evaluated for 56 jobs by 2 evaluators blinded to morbidity measures. Jobs then were assigned to dichotomous hazard classifications (problem versus safe) according to recommendations from the literature. OSHA 200 logs were used to ascertain historical evidence of distal upper extremity (DUE) morbidity, and jobs were assigned to a dichotomous morbidity classification (positive versus negative) using none versus one or more recorded cases as the criterion. Evidence of association and measures of predictive validity were evaluated by comparing hazard and morbidity classifications using 2 x 2 contingency tables. Five individual generic risk factors, three generic risk factor combinations, and the presence of any generic risk factor were not associated with morbidity classification. The odds ratio estimates among the four individual generic risk factors and the five combinations of generic risk factors associated with DUE morbidity varied from 3.3-36.0. The Strain Index had the largest estimated odds ratio of any exposure factor at 108.3. The exposure methods were grouped according to patterns of predictive validity. With one exception, the individual generic risk factors and their combinations had high sensitivity with low specificity (many false-positives), low sensitivity with high specificity (many false-negatives), or low sensitivity with low specificity. The only generic risk factor that demonstrated reasonable predictive validity was the use of gloves--its sensitivity, specificity, positive predictive value, and negative predictive value were equal to 0.75. The Strain Index performed better than any of the individual or combinations of generic risk factors. Its sensitivity, specificity, positive predictive value, and negative predictive value were all approximately 0.90.

Autonomic healing of polymer composites

Structural polymers are susceptible to damage in the form of cracks, which form deep within the structure where detection is difficult and repair is almost impossible. Cracking leads to mechanical degradation of fibre-reinforced polymer composites; in microelectronic polymeric components it can also lead to electrical failure. Microcracking induced by thermal and mechanical fatigue is also a long-standing problem in polymer adhesives. Regardless of the application, once cracks have formed within polymeric materials, the integrity of the structure is significantly compromised. Experiments exploring the concept of self-repair have been previously reported, but the only successful crack-healing methods that have been reported so far require some form of manual intervention. Here we report a structural polymeric material with the ability to autonomically heal cracks. The material incorporates a microencapsulated healing agent that is released upon crack intrusion. Polymerization of the healing agent is then triggered by contact with an embedded catalyst, bonding the crack faces. Our fracture experiments yield as much as 75% recovery in toughness, and we expect that our approach will be applicable to other brittle materials systems (including ceramics and glasses).

Surface-directed liquid flow inside microchannels

Self-assembled monolayer chemistry was used in combination with either multistream laminar flow or photolithography to pattern surface free energies inside microchannel networks. Aqueous liquids introduced into these patterned channels are confined to the hydrophilic pathways, provided the pressure is maintained below a critical value. The maximum pressure is determined by the surface free energy of the liquid, the advancing contact angle of the liquid on the hydrophobic regions, and the channel depth. Surface-directed liquid flow was used to create pressure-sensitive switches inside channel networks. The ability to confine liquid flow inside microchannels with only two physical walls is expected to be useful in applications where a large gas-liquid interface is critical, as demonstrated here by a gas-liquid reaction.

Microfluidic tectonics: a comprehensive construction platform for microfluidic systems

A microfluidic platform for the construction of microscale components and autonomous systems is presented. The platform combines liquid-phase photopolymerization, lithography, and laminar flow to allow the creation of complex and autonomous microfluidic systems. The fabrication of channels, actuators, valves, sensors, and systems is demonstrated. Construction times can be as short as 10 min, providing ultrarapid prototyping of microfluidic systems.

Immune monitoring in xenotransplantation: the multiparameter flow cytometric mixed lymphocyte culture assay

Xenotransplantation requires monitoring of complex cellular interactions in vitro. A tool to monitor cell proliferation in detail would be instrumental in understanding these cellular interactions in heterogeneous xenogeneic lymphocyte cultures and in patients after xenotransplantation. To accomplish this, we used a fluorescent cell proliferation marker, 5,6-carboxyfluorescein diacetate succinimidyl ester (CFSE), in combination with flow cytometry. CFSE, a green fluorescent molecule, binds covalently to intracellular macromolecules. Each cell division reduces the fluorescent intensity per cell by half and shows a characteristic multipeak pattern in flow cytometric analysis. For this study, human lymphocytes were labeled with CFSE and cultured in the presence of irradiated porcine lymphocytes. Cell proliferation was detected in CFSE-labeled lymphocytes in both a single and a multiparameter flow cytometry setting. Concurrently, tritiated ((3)H) thymidine incorporation, a common method to measure gross cell proliferation, was assessed. The kinetics of CFSE-labeled cell proliferation correlated with (3)H-thymidine incorporation in that both methods showed a lag phase for days 1-3 and a log phase for days 4-7. Multiparameter flow cytometric monitoring of mixed lymphocyte cultures allowed phenotyping and assessment of viability of proliferating populations in heterogeneous xenogeneic stimulated human lymphocyte cultures and complemented the classical (3)H-thymidine incorporation assay. The use of this technique will allow a wide array of immunologic parameters to be measured in a heterogeneous xenogeneic mixed lymphocyte culture. The information gained from these assays is essential to understanding the biological significance of xenogeneic cellular interaction and for monitoring the immune status of the xenotransplanted patient.

Novel polymers: molecular to nanoscale order in three dimensions

The assembly of polymer chains in solution is a powerful method that is leading to the preparation of interesting and unique macromolecular-based synthetic nanostructures. Specific control over the intramolecular and intermolecular physical interactions dictates either the folding of single chains or the aggregation and ordering of multiple chains. This control is provided through the selective placement of functional groups along the polymer backbone and the relative strengths of their attractive and repulsive interactions.

Classification criteria and severity assessment in work-associated upper extremity disorders: methods matter

Work-associated musculoskeletal disorders of the upper extremity are common and disabling. Research on these disorders is needed and requires valid methods of classification of the disorders for epidemiologic studies and measurement of their impact on functional status. This commentary discusses the methodologic aspects of classification and functional status assessment in upper extremity musculoskeletal disorders.

Replacement of graft-resident donor-type antigen presenting cells alters the tempo and pathogenesis of murine cardiac allograft rejection

BACKGROUND

Graft-resident antigen presenting cells (APCs) are potent stimulators of the alloresponse. To test whether replacement of graft-resident donor-type APCs with those of recipient-type alters allorecognition and the pathogenesis of both acute and chronic rejection, we created chimeric hearts for transplantation into naive recipients.

METHODS

To replace donor-type APCs with those of recipient-type, chimeric animals were created by bone marrow transplantation (BMT) in fully allogeneic mouse and rat strain combinations. The degree of APC replacement in chimeric organs was assessed phenotypically and functionally. Chimeric hearts were transplanted heterotopically into untreated recipients.

RESULTS

Flow cytometric and immunohistochemical analysis did not detect residual bone marrow recipient-type APCs in mouse BMT chimeras. Although semi-quantitative reverse transcription polymerase chain reaction detected 0.001-0.01% residual cells, APCs isolated from chimeric organs were functionally unable to stimulate donor-type cells. When transplanted into naive recipients, chimeric mouse hearts had significantly prolonged survival but were nevertheless rejected acutely. Similar results were obtained in the ACI --> LEW rat strain combination. However, in the PVG --> DA rat model, the majority of chimeric hearts survived >100 days and all long-surviving hearts developed cardiac allograft vasculopathy.

CONCLUSIONS

BMT leads to near complete replacement of organ-resident APCs. The virtual absence of donor-type APCs in chimeric hearts delays or prevents acute rejection in a strain-dependent manner. In contrast, this type of graft modification does not prevent cardiac allograft vasculopathy. This suggests that, although the CD4+ direct pathway may play a role in acute rejection, it is not essential for the development of chronic rejection in rodent cardiac allografts.

Flexor tendon entrapment of the digits (trigger finger and trigger thumb)

Flexor tendon entrapment of the digits is a disorder characterized by snapping or locking of the thumb or fingers (with or without pain). Most cases are secondary to thickening of the digit's A1 pulley, but other pathogeneses include tendon abnormalities at the level of the carpal tunnel, thickening of other pulleys, and abnormalities of the metacarpal-phalangeal joint. Its historical name, stenosing tenosynovitis of the digits, is inappropriate because histological studies document a lack of inflammation. Flexor tendon entrapment of the digits is a relatively common, uncomplicated, and non-controversial musculotendinous disorder of the distal upper extremity. The purpose of this invited review is to summarize information from the medical literature on aspects of this condition likely to be of interest and relevant to occupational medicine practitioners. Topics covered include normal anatomy and kinesiology, history, clinical observations related to diagnosis, pathology, pathophysiology, clinical observations on etiology, descriptive epidemiology, epidemiological studies, and case management. Models for the pathogenesis of flexor tendon entrapment of the digits are proposed, and opportunities for future research are presented.

Mycobacterial contamination of metalworking fluids: involvement of a possible new taxon of rapidly growing mycobacteria

Contamination of air and metalworking fluid (MWF) systems with a rapidly growing mycobacterium (RGM) was detected in 1995 in a single manufacturing plant with recent cases of hypersensitivity pneumonitis (HP). Extensive environmental sampling was performed to determine the extent of the contamination and its variability over time. RGM were present in multiple indoor air samples, 100% of the central MWF storage tanks, and 75% of the freestanding cutting, drilling, and grinding machines. With one exception, contamination was limited to a recently introduced formulation (brand) of semisynthetic MWF used in 95% of the facility's machining operations. In general, the mycobacterial counts were stable over time, with the degree of contamination ranging from 10(2)-10(7) colony forming units (CFU)/mL. A few systems were culture positive for the mycobacterium (> 10(1) CFU/mL), changed to culture negative (< 10(1) CFU/mL), then changed back to culture positive without explanation. Samples obtained from diluted (5%) but unused MWF, a replenishment line with 2% unused MWF, an MWF pasteurizer, city water, and deionized water were culture negative for this species of mycobacterium. Inoculation and growth studies demonstrated that this mycobacterium does not grow in liquid samples of 5% unused MWF. By molecular techniques, the mycobacterial isolates consisted of a single strain and represented a previously undescribed taxon closely related to Mycobacterium chelonae/abscessus. The relationship of this mycobacterium to the cases of HP is unknown.