Hello darkness, my old friend: 3-KETOACYL-COENZYME A SYNTHASE4 is a branch point in the regulation of triacylglycerol synthesis in Arabidopsis thaliana

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.

The carbon monoxide releasing molecule (CORM-3) inhibits expression of vascular cell adhesion molecule-1 and E-selectin independently of haem oxygenase-1 expression

BACKGROUND AND PURPOSE

Although carbon monoxide (CO) can modulate inflammatory processes, the influence of CO on adhesion molecules is less clear. This might be due to the limited amount of CO generated by haem degradation. We therefore tested the ability of a CO releasing molecule (CORM-3), used in supra-physiological concentrations, to modulate the expression of vascular cell adhesion molecule (VCAM)-1 and E-selectin on endothelial cells and the mechanism(s) involved.

EXPERIMENTAL APPROACH

Human umbilical vein endothelial cells (HUVECs) were stimulated with tumour necrosis factor (TNF)-alpha in the presence or absence of CORM-3. The influence of CORM-3 on VCAM-1 and E-selectin expression and the nuclear factor (NF)-kappaB pathway was assessed by flow cytometry, Western blotting and electrophoretic mobility shift assay.

KEY RESULTS

CORM-3 inhibited the expression of VCAM-1 and E-selectin on TNF-alpha-stimulated HUVEC. VCAM-1 expression was also inhibited when CORM-3 was added 24 h after TNF-alpha stimulation or when TNF-alpha was removed. This was paralleled by deactivation of NF-kappaB and a reduction in VCAM-1 mRNA. Although TNF-alpha removal was more effective in this regard, VCAM-1 protein was down-regulated more rapidly when CORM-3 was added. CORM-3 induced haem oxygenase-1 (HO-1) in a dose- and time-dependent manner, mediated by the transcription factor, Nrf2. CORM-3 was still able to down-regulate VCAM-1 expression in HUVEC transfected with siRNA for HO-1 or Nrf2.

CONCLUSIONS AND IMPLICATIONS

Down-regulation of VCAM and E-selectin expression induced by CORM-3 was independent of HO-1 up-regulation and was predominantly due to inhibition of sustained NF-kappaB activation.

[Patellar instability]

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.

Lead poisoning risk determination in a rural setting

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.

Expression of Fc epsilon receptors on activated human T lymphocytes

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.