Search

The assembly and function of cilia on Caenorhabditis elegans neurons depends on the action of two kinesin-2 motors, heterotrimeric kinesin-II and homodimeric OSM-3-kinesin, which cooperate to move the same intraflagellar transport (IFT) particles along microtubule (MT) doublets. Using competitive in vitro MT gliding assays, we show that purified kinesin-II and OSM-3 cooperate to generate movement similar to that seen along the cilium in the absence of any additional regulatory factors. Quantitative modeling suggests that this could reflect an alternating action mechanism, in which the motors take turns to move along MTs, or a mechanical competition, in which the motors function in a concerted fashion to move along MTs with the slow motor exerting drag on the fast motor and vice versa. In vivo transport assays performed in Bardet-Biedl syndrome (BBS) protein and IFT motor mutants favor a mechanical competition model for motor coordination in which the IFT motors exert a BBS protein-dependent tension on IFT particles, which controls the IFT pathway that builds the cilium foundation.

OSM-3 is a Kinesin-2 family member from Caenorhabditis elegans that is involved in intraflagellar transport (IFT), a process essential for the construction and maintenance of sensory cilia. In this study, using a single-molecule fluorescence assay, we show that bacterially expressed OSM-3 in solution does not move processively (multiple steps along a microtubule without dissociation) and displays low microtubule-stimulated adenosine triphosphatase (ATPase) activity. However, a point mutation (G444E) in a predicted hinge region of OSM-3's coiled-coil stalk as well as a deletion of that hinge activate ATPase activity and induce robust processive movement. These hinge mutations also cause a conformational change in OSM-3, causing it to adopt a more extended conformation. The motility of wild-type OSM-3 also can be activated by attaching the motor to beads in an optical trap, a situation that may mimic attachment to IFT cargo. Our results suggest that OSM-3 motility is repressed by an intramolecular interaction that involves folding about a central hinge and that IFT cargo binding relieves this autoinhibition in vivo. Interestingly, the G444E allele in C. elegans produces similar ciliary defects to an osm-3-null mutation, suggesting that autoinhibition is important for OSM-3's biological function.

P. Voland [1] N. Neumayer [1] N. Endres [1] M. Zeitner [1] H. Wagner [2] C. Prinz [1] [4/01] [*] Antigenic Potential of HpaA and Omp18, two Helicobacter pylori Outer [...]

N. Endres [1] P. Voland [1] N. Neumayer [1] M. Gerhard [1] H. Wagner [2] C. Prinz [1] [4/05] Incubation of Peripheral Blood Lymphocytes with H. pylori Leads To a [...]

Introduction: Although H. pylori is recognised by the human immune system, the bacteria are not eliminated and lead to a chronic inflammation of the gastric mucosa. Therefore, mechanisms of immune evasion have been postulated and are investigated in this study. Methods: Human peripheral blood lymphocytes (PBL) were isolated from H. pylori infected patients and separated via Ficoll gradient. Following 5 days of culture, PBL and isolated T-cells were stimulated with phythemeagglutinin (PHA) or a-CD3/CD28 beads, resp., and incubated with different H. pylori strains. Clonal expansion of T-cells was determined by 3H-thymidine incorporation. Cell cycle analysis was performed by FACS-Scan analysis and western blot. Results: Simultaneous incubation with H. pylori 26696, Tx30a or a number of other strains (including CagA-, VacA-, BabA-mutant strains) induced a significant decrease in proliferation. These effects were independent of the H. pylori strain type. E.coli and C. jejuni had no effect on T-cells. Addition of IL-2, a-TGFb, a-TNF or a-IL-1 did not counteract the effect. To determine the way of inhibition, cell cycle analysis of T-cells was determined by FACS. In resting T-cells, only a minority underwent DNA-replication in the S-phase (0.2%). In contrast, stimulation with PHA or a-CD3/CD28 strongly induced proliferation (40x). Incubation of T-cells with H. pylori strains completely prevented entry into S-phase (total number: 0.3%) at MOI 1, while E. coli or C. jejuni had no effect. Western blot analysis of inhibited T-cells revealed markedly reduced phosphorylation of the Retinoblastoma (Rb) protein, a major gatekeeper of the cell cycle in T-cells. Also, cyclin D3 and cyclin E (which control Rb) were downregulated. Conclusion: H. pylori, independent of the strain type, leads to G1 arrest of T-cells at bacterial concentrations comparable to the density of lymphocytic infiltration. Immune evasion by induction of a G1 arrest may be of importance for the chronic... [ABSTRACT FROM AUTHOR]

Background: This study investigates the potential role of preoperative 25(OH)D supplementation as a cost-effective strategy to decrease revision rotator cuff repair (RCR) rates and lower the total health care burden from patients undergoing primary arthroscopic RCR. Previous literature has emphasized the importance of vitamin D on bone health maintenance, soft tissue healing, and outcomes in RCR. Inadequate preoperative vitamin D levels may increase revision RCR rates following primary arthroscopic RCR. Although 25(OH)D deficiency is common in RCR patients, serum screening is not routinely performed., Methods: A cost-estimation model was developed to determine the cost-effectiveness of both preoperative selective and nonselective 25(OH)D supplementation in RCR patients in order to reduce revision RCR rates. Prevalence and surgical cost data were obtained from published literature through systematic reviews. Cost of serum 25(OH)D assay and supplementation were obtained from public-use data. Mean and lower and upper bounds of 1-year cost savings were calculated for both the selective and nonselective supplementation scenarios., Results: Preoperative 25(OH)D screening and subsequent selective 25(OH)D supplementation was calculated to result in a mean cost savings of $6,099,341 (range: -$2,993,000 to $15,191,683) per 250,000 primary arthroscopic RCR cases. Nonselective 25(OH)D supplementation of all arthroscopic RCR patients was calculated to result in a mean cost savings of $11,584,742 (range: $2,492,401-$20,677,085) per 250,000 primary arthroscopic RCR cases. Univariate adjustment projects that selective supplementation is a cost-effective strategy in clinical contexts where the cost of revision RCR exceeds $14,824.69 and prevalence of 25(OH)D deficiency exceeds 6.67%. Additionally, nonselective supplementation is a cost-effective strategy in clinical scenarios where revision RCR cost is ≥$4216.06 and prevalence of 25(OH)D deficiency is ≥1.93%., Conclusions: This cost-predictive model promotes the role of preoperative 25(OH)D supplementation as a cost-effective mechanism to reduce revision RCR rates and lower the overall health care burden from arthroscopic RCR. Nonselective supplementation appears to be more cost-effective than selective supplementation, likely due to the lower cost of 25(OH)D supplementation compared to serum assays., (Copyright © 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Previous studies of concomitant meniscal injury in athletes with anterior cruciate ligament (ACL) injury have examined age, sex, body mass index (BMI), injury mechanism, and time from injury to surgery as potential risk factors., Purpose: To identify additional risk factors for concomitant meniscal injury, including preinjury joint laxity and lower extremity alignment, in athletes with sport-related ACL injury., Study Design: Cross-sectional study; Level of evidence, 3., Methods: This study included 180 participants aged 13 to 26 years who underwent ACL reconstruction (ACLR) after a first-time ACL injury sustained during participation in sport. Contralateral lower extremity alignment and joint laxity were used as surrogate measures for the injured knee before trauma. Concomitant meniscal tear patterns were identified at the time of ACLR. Sex-specific analyses were conducted., Results: Concomitant meniscal injury was observed in 60.6% of the subjects. The prevalence of concomitant injury was higher in male than female participants (69.9% vs 54.2%; P  = .035) due to a higher prevalence of lateral meniscal injuries (56.2% vs 38.3%; P  = .018). Among male patients, there was a significant difference in the prevalence of concomitant lateral meniscal tear according to sport participation (≥9 vs <9 h/week: 67.4% vs 35.7%; P  = .032). Among male patients, the likelihood of concomitant injury to both the lateral and medial menisci increased by 28.8% for each 1-mm decrease in navicular drop. Among female patients, the likelihood of concomitant injury to the lateral meniscus increased by 15% per degree increase in genu recurvatum and 14% per degree decrease in standing quadriceps angle, with similar effects on the likelihood of concurrent injury to both the lateral and medial menisci., Conclusion: Measures of lower extremity alignment and genu recurvatum previously identified as risk factors for ACL injury were also associated with concomitant meniscal injury in female patients while other risk factors, including BMI and joint laxity, were not. Increased time spent participating in sport and navicular drop were associated with concomitant meniscal injury in male patients., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: this investigation was funded by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the United States National Institutes of Health (grant RO1 AR050421). A.G. has received education payments from Arthrex, consulting fees from Smith & Nephew, nonconsulting fees from Arthrex and Smith & Nephew, and hospitality payments from Stryker. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto., (© The Author(s) 2023.)

Plant lipids are important as alternative sources of carbon and energy when sugars or starch are limited. Here, we applied combined heat and darkness or extended darkness to a panel of ∼300 Arabidopsis (Arabidopsis thaliana) accessions to study lipid remodeling under carbon starvation. Natural allelic variation at 3-KETOACYL-COENZYME A SYNTHASE4 (KCS4), a gene encoding an enzyme involved in very long chain fatty acid (VLCFA) synthesis, underlies the differential accumulation of polyunsaturated triacylglycerols (puTAGs) under stress. Ectopic expression of KCS4 in yeast and plants proved that KCS4 is a functional enzyme localized in the endoplasmic reticulum with specificity for C22 and C24 saturated acyl-CoA. Allelic mutants and transient overexpression in planta revealed the differential role of KCS4 alleles in VLCFA synthesis and leaf wax coverage, puTAG accumulation, and biomass. Moreover, the region harboring KCS4 is under high selective pressure and allelic variation at KCS4 correlates with environmental parameters from the locales of Arabidopsis accessions. Our results provide evidence that KCS4 plays a decisive role in the subsequent fate of fatty acids released from chloroplast membrane lipids under carbon starvation. This work sheds light on both plant response mechanisms and the evolutionary events shaping the lipidome under carbon starvation., Competing Interests: Conflict of interest statement. None declared., (© The Author(s) 2023. Published by Oxford University Press on behalf of American Society of Plant Biologists.)

Small molecule inhibitors that target the phosphatidylinositol 3-kinase (PI3K) signaling pathway have received significant interest for the treatment of cancers. The class I isoform PI3Kα is most commonly associated with solid tumors via gene amplification or activating mutations. However, inhibitors demonstrating both PI3K isoform and mutant specificity have remained elusive. Herein, we describe the optimization and characterization of a series of benzoxazepin-oxazolidinone ATP-competitive inhibitors of PI3Kα which also induce the selective degradation of the mutant p110α protein, the catalytic subunit of PI3Kα. Structure-based design informed isoform-specific interactions within the binding site, leading to potent inhibitors with greater than 300-fold selectivity over the other Class I PI3K isoforms. Further optimization of pharmacokinetic properties led to excellent in vivo exposure and efficacy and the identification of clinical candidate GDC-0077 (inavolisib, 32 ), which is now under evaluation in a Phase III clinical trial as a treatment for patients with PIK3CA -mutant breast cancer.

Purpose: Injury to the anterior cruciate ligament (ACL) is common in alpine skiing in the form of either an intra-substance ACL tear or anterior tibial spine fracture (ATSF). Anterior tibial spine fractures are typically reported in children. However, several case reports describe these injuries in adults while skiing. The purpose of this study is to describe the sport specific incidence of ATSF in alpine skiing., Methods: The study was conducted over a 22-year period. Skiers who suffered an ATSF were identified and radiographs were reviewed to confirm the diagnosis. Additionally, control data from intra-substance ACL injury groups were collected. The incidence of these injuries in children, adolescents, and adults (grouped as ages 0-10, 11-16, and 17 + years old, respectively) was evaluated and the risk factors for ATSF versus ACL tear were determined., Results: There were 1688 intra-substance ACL and 51 ATSF injuries. The incidence of intra-substance ACL injury was greater in adults (40.0 per 100,000 skier days) compared to the adolescent (15.4 per 100,000) and child (1.1 per 100,000) age groups. In contrast, the incidence of ATSF was similar in the adult (0.9 per 100,000), adolescent (1.9 per 100,000), and child (1.9 per 100,000) age groups. Loose ski boot fit was identified as a risk factor for ATSF., Conclusion: The incidence of ATSF in alpine skiers is similar among all age groups. However, the incidence of intra-substance ACL injuries is far greater in adult skiers compared to adolescents and children. Risk factors for ATSF relate to compliance between the foot/ankle and the ski boot., Level of Evidence: III., (© 2021. The Author(s) under exclusive licence to European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA).)

PIK3CA is one of the most frequently mutated oncogenes; the p110a protein it encodes plays a central role in tumor cell proliferation. Small-molecule inhibitors targeting the PI3K p110a catalytic subunit have entered clinical trials, with early-phase GDC-0077 studies showing antitumor activity and a manageable safety profile in patients with PIK3CA -mutant breast cancer. However, preclinical studies have shown that PI3K pathway inhibition releases negative feedback and activates receptor tyrosine kinase signaling, reengaging the pathway and attenuating drug activity. Here we discover that GDC-0077 and taselisib more potently inhibit mutant PI3K pathway signaling and cell viability through unique HER2-dependent mutant p110a degradation. Both are more effective than other PI3K inhibitors at maintaining prolonged pathway suppression. This study establishes a new strategy for identifying inhibitors that specifically target mutant tumors by selective degradation of the mutant oncoprotein and provide a strong rationale for pursuing PI3Kα degraders in patients with HER2-positive breast cancer. SIGNIFICANCE: The PI3K inhibitors GDC-0077 and taselisib have a unique mechanism of action; both inhibitors lead to degradation of mutant p110a protein. The inhibitors that have the ability to trigger specific degradation of mutant p110a without significant change in wild-type p110a protein may result in improved therapeutic index in PIK3CA -mutant tumors. See related commentary by Vanhaesebroeck et al., p. 20 . This article is highlighted in the In This Issue feature, p. 1 ., (©2021 The Authors; Published by the American Association for Cancer Research.)

Primary endothelial cells are fully resistant to TNF-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis. Here, we demonstrate that certain environmental conditions, such as exposure to the widespread allergen nickel, can dramatically increase the susceptibility of naturally resistant primary endothelial cells or keratinocytes to TRAIL-induced apoptosis. While nickel treatment increased surface expression of the apoptosis-inducing TRAIL receptors TRAIL-R1 and TRAIL-R2, it also up-regulated the apoptosis-deficient TRAIL-R4, suggesting that modulation of TRAIL receptor expression alone is unlikely to fully account for the dramatic sensitization effect of nickel. Further analysis of candidate mediators revealed that nickel strongly repressed c-FLIP at mRNA and protein levels. Accordingly, increased activation of Caspase-8 and Caspase-3 following nickel treatment was observed. Importantly, depletion of c-FLIP by RNA interference could largely recapitulate the effect of nickel and sensitize endothelial cells to TRAIL-dependent apoptosis in the absence of nickel pre-treatment. Conversely, ectopic expression of c-FLIP(L) largely protected nickel-treated cells from TRAIL-mediated apoptosis. Our data demonstrate that one key mechanism of sensitization of primary human endothelial cells or keratinocytes is transcriptional down-regulation of c-FLIP. We hypothesize that environmental factors, exemplified by the contact allergen nickel, strongly modulate death ligand sensitivity of endothelial cells and keratinocytes thus influencing vascular and epidermal function and integrity under physiological and pathophysiological conditions.

Endothelial cells (EC) actively participate in the innate defense against microbial pathogens. Under unfavorable conditions, defense reactions can turn life threatening resulting in sepsis. We therefore studied the so far largely unknown EC reaction patterns to the fungal pathogen Candida albicans, which is a major cause of lethality in septic patients. Using oligonucleotide microarray analysis, we identified 56 genes that were transcriptionally up-regulated and 69 genes that were suppressed upon exposure of ECs to C. albicans. The most significantly up-regulated transcripts were found in gene ontology groups comprising the following categories: chemotaxis/migration; cell death and proliferation; signaling; transcriptional regulation; and cell-cell contacts/intercellular signaling. Further examination of candidate signaling cascades established a central role of the proinflammatory NF-kappaB pathway in the regulation of the Candida-modulated transcriptome of ECs. As a second major regulatory pathway we identified the stress-activated p38 MAPK pathway, which critically contributes to the regulation of selected Candida target genes such as CXCL8/IL-8. Depletion of MyD88 and IL-1R-associated kinase-1 by RNA interference demonstrates that Candida-induced NF-kappaB activation is mediated by pattern recognition receptor signaling. Additional experiments suggest that C. albicans-induced CXCL8/IL-8 expression is mediated by TLR3 rather than TLR2 and TLR4, which previously have been implicated with MyD88/IkappaB kinase-2/NF-kappaB activation by this fungus in other systems. Our study provides the first comprehensive analysis of endothelial gene responses to C. albicans and presents novel insights into the complex signaling patterns triggered by this important pathogen.

Background: Parathyroid surgery (PTX) in patients with tertiary hyperparathyroidism (tHPT) may endanger the long-term survival of transplanted renal grafts. The mechanism by which graft function deteriorates is unknown. We reviewed our experience in regard to the operative procedures and postoperative outcome., Methods: Sixty-nine patients were operated on for tHPT between 1987 and 2006 at our institution. Serum (s) calcium, s-creatinine, and levels of intact parathyroid hormone (PTH) were measured before and after PTX. The Modification of Diet in Renal Disease (MDRD) equation was used to estimate glomerular filtration rate (GFR)., Results: The entire patient group developed a deterioration of kidney graft function after PTX. Nineteen of 69 patients developed a decrease in GFR of more than 20% during the hospital stay, persisting for more than one year after PTX. Ten of them had to restart dialysis during the first year after PTX. Mean preoperative s-creatinine was 4.4 +/- 0.6 mg/dl in these patients. When divided according to the surgical procedure performed, only the subgroup who underwent total parathyroidectomy showed a significant worsening of graft function when compared to subtotal or reoperative PTX., Conclusions: PTX is an efficient way to treat tHPT but represents a risk for impairing graft function, especially for patients that already demonstrate poor kidney function at the time of surgery. In the aim to prevent transient hypoparathyroidism, which may provoke reduced graft perfusion, as one possible cause of kidney graft deterioration associated with PTX, one should consider subtotal instead of total parathyroidectomy.

We report a retrospective study of patients with patellar instability, all treated by operation and followed up for 3 years. Patients with recurrent dislocation of the patella, lateral displacement and primary patella dislocation were treated by a Elmslie-Trillat reconstruction combined with a soft tissue intervention. Preoperative and follow-up radiographic evaluation included weight bearing anteroposterior view and merchant view. Evaluation was done using the Insall-Salvati index, sulcus and congruence angle. The operation was performed on 23 patients. The clinical evaluation at follow-up was performed using the Knee-Society- and Tegner-Score. Subjective results of the operation were excellent or good in 22 of the 23 at three years with a redislocation rate of only 1 out of 26. Most patients were able to return to the same level of sporting activity as before the injury. The technique described in this paper tries to correct as much as possible of the abnormal parameters in patellar instability to achieve a dynamic stability of the patella through the full range of motion. The excellent results are presumable explained by the use of the combined technique.

Study Design: A retrospective case control analysis of 48 cases of postoperative infection following spinal procedures., Objectives: Spinal procedures that became infected after surgery were analyzed to identify the significance of preoperative and intraoperative risk factors. Characterization of the nature and timing of the infections was also performed., Summary of Background Data: The rate of postoperative infection following spinal surgery varies widely depending on the nature of the procedure and the patient's diagnosis. Preoperative comorbidities and risk factors also influence the likelihood of infection., Methods: A review of 1629 procedures performed on 1095 patients revealed that a postoperative infection developed in 48 patients (4.4%). Data regarding preoperative and intraoperative risk factors were gathered from patient charts for these and a randomly selected control group of 95 uninfected patients. For analysis, these patient groups were further divided into adult and pediatric subgroups, with an age cutoff of 18 years. Preoperative risk factors reviewed included smoking, diabetes, previous surgery, previous infection, steroid use, body mass index, and alcohol abuse. Intraoperative factors reviewed included staging of procedures, estimated blood loss, operating time, and use of allograft or instrumentation., Results: The majority of infections occurred during the early postoperative period (less than 3 months). Age >60 years, smoking, diabetes, previous surgical infection, increased body mass index, and alcohol abuse were statistically significant preoperative risk factors. The most likely procedure to be complicated by an infection was a combined anterior/posterior spinal fusion performed in a staged manner under separate anesthesia. Infections were primarily monomicrobial, although 5 patients had more than 4 organisms identified. The most common organism cultured from the wounds was Staphylococcus aureus. All patients were treated with surgical irrigation and débridement, and appropriate antibiotics to treat the cultured organism., Conclusions: Aggressive treatment of patients undergoing complex or prolonged spinal procedures is essential to prevent and treat infections. Understanding a patient's preoperative risk factors may help the physician to optimize a patient's preoperative condition. Additionally, awareness of critical intraoperative parameters will help to optimize surgical treatment. It may be appropriate to increase the duration of prophylactic antibiotics or implement other measures to decrease the incidence of infection for high risk patients.

Background & Aims: Although Helicobacter pylori is recognized by the human immune system, the bacteria are not eliminated and lead to a chronic inflammation of the gastric mucosa., Methods: We investigated the interaction of H. pylori with human lymphocytes. T and B lymphocytes were isolated from H. pylori-infected patients and stimulated with anti-CD3/CD28 or interleukin-6., Results: Proliferation of lymphocytes was abolished on co-incubation with different H. pylori strains (1-5 bacteria/cell) or with protein extracts of culture supernatants. Inhibition of proliferation was independent of known virulence factors. The factor is a protein or protein complex with an apparent molecular weight between 30 and 60 kilodaltons, clearly distinct from VacA. Although antigen-specific activation of T cells (as shown by nuclear factor of activated T cells [NFAT]-activation, interferon-gamma production, and CD25 or CD69 up-regulation) remained intact, cell-cycle analysis showed that S-phase entry of T cells was inhibited completely by H. pylori. Consequently, stimulated T cells arrested in the G1 phase of the cell cycle. Western blot analysis showed markedly reduced phosphorylation of the retinoblastoma protein (pRb), suggesting inhibition of G1 cyclin-dependent kinase activity. In line with this, activities of cyclin D3 and cyclin E were down-regulated, and levels of the cyclin-dependent kinase inhibitor p27Kip1 were increased. Mouse embryonic fibroblasts deficient in p27 showed a decrease in H. pylori-induced inhibition of cell proliferation, suggesting a central role for p27 in mediating H. pylori-induced G1 arrest., Conclusions: Induction of cell-cycle arrest in lymphocytes may be of major significance for the chronic persistence of bacteria in the human stomach.

Objectives: To determine the prevalence of elevated blood lead levels among children living in a rural area and to determine the effectiveness of the Centers for Disease Control and Prevention (CDC) Lead Risk Assessment Questionnaire and additional questionnaire items in correctly identifying rural children having elevated blood lead levels., Research Design: Comparison of results of a questionnaire that is intended to identify children as being at low or high risk for lead poisoning with children's blood lead levels., Setting: The three practice sites of the only pediatric group in a rural county of upstate New York., Patients: A consecutive sample of 705 children ages 6 to 72 months who were seen for health supervision visits between June and September 1993., Results: Sixty-nine percent of the children were considered to be at high risk for lead poisoning by the CDC questionnaire. Overall, 8.4% of the children in the study had blood lead levels of 10 micrograms/dL (0.48 mumol/L) or higher, and 2.1% had blood lead levels of 15 micrograms/dL (0.72 mumol/L) or higher. No significant difference was noted between the percentages of high- and low-risk children who had elevated blood lead levels. To devise a more effective lead risk assessment tool for children in this setting, the two items from the CDC questionnaire and the two additional items that had the greatest predictive utility were combined to form a short alternative questionnaire. The alternative questionnaire thus consisted of items concerning whether the child has a sibling or playmate with lead poisoning, whether the child lives near an industry that potentially may release lead, whether the child lives in rented or owner-occupied housing, and whether the child has a parent who is a migrant farm worker. Children categorized as high risk with the alternative questionnaire were much more likely to have elevated blood lead levels than those who were categorized as low risk. The alternative questionnaire was very effective in correctly identifying children with elevated blood lead levels. Eighty-eight percent of children having blood lead levels of 10 micrograms/dL or higher and 100% of children having blood lead levels of 15 micrograms/dL or higher were classified as high risk by the questionnaire. Children classified as low risk were very unlikely to have elevated blood lead levels; 98% of low-risk children had blood lead levels of less than 10 micrograms/dL, and 100% had blood lead levels of less than 15 micrograms/dL., Conclusions: These results suggest that the CDC lead risk assessment questionnaire is of limited benefit in identifying rural children with blood lead levels 10 micrograms/dL or higher or 15 micrograms/dL or higher. An alternative questionnaire, however, seems to have marked clinical utility for identifying rural children with elevated blood lead levels.

Our results clearly demonstrate that the low-affinity receptor for IgE (Fc epsilon R) is an activation antigen transiently expressed on a subpopulation of human T lymphocytes. It can be selectively induced by stimulation with certain antigens or lectins, but it is not found on resting T cells. The increased numbers of activated Fc epsilon R+ T cells observed after stimulation of peripheral blood mononuclear cells (PBMC) from bee venom allergic patients with the specific allergen phospholipase A2 (PLA2) suggest that Fc epsilon R+ T cells might very well be involved in the regulation of the human IgE response against the respective antigen. These results were obtained by the use of two monoclonal antibodies, M-L25 and M-L47, which were raised against the human low-affinity Fc epsilon R in our laboratory. After stimulation of PBMC with phytohemagglutinin a peak of 7.6 +/- 6% Fc epsilon R+ T cells was observed on day 3, with pokeweed mitogen of 0.8 +/- 0.8% on days 2 and 3, and with concanavalin A of 0.6 +/- 0.7% Fc epsilon R+ T cells on day 2. Stimulation of PBMC with tetanus toxoid (TT) induced Fc epsilon R on maximally 0.6 +/- 0.8% of the total T cells (day 4), stimulation with purified protein derivative from tuberculin (PPD) on 0.2 +/- 0.6% of the T cells (day 2). In contrast to these antigens, stimulation of PBMC from bee venom allergic patients with PLA2 induced as a peak 2.5 +/- 2.5% of the total T cells to express Fc epsilon R (day 5), although the stimulated T cell population was much smaller than with TT or PPD, as was shown by their stimulation indices. The allergen-stimulated Fc epsilon R+ T cells were exclusively T4+. The Fc epsilon R-expression index was determined, which for a specific antigen or lectin correlates the percentage of Fc epsilon R+ T cells to the stimulated T cell population, respectively.