What are the implications of variation in root hair length on tolerance to phosphorus deficiency in combination with water stress in barley (Hordeum vulgare)?

BACKGROUND AND AIMS: Phosphorus commonly limits crop yield and is frequently applied as fertilizer; however, supplies of quality rock phosphate for fertilizer production are diminishing. Plants have evolved many mechanisms to increase their P-fertilizer use efficiency, and an understanding of these traits could result in improved long-term sustainability of agriculture. Here a mutant population is utilized to assess the impact of root hair length on P acquisition and yield under P-deficient conditions alone or when combined with drought. METHODS: Mutants with various root hair phenotypes were grown in the glasshouse in pots filled with soil representing sufficient and deficient P treatments and, in one experiment, a range of water availability was also imposed. Plants were variously harvested at 7 d, 8 weeks and 14 weeks, and variables including root hair length, rhizosheath weight, biomass, P accumulation and yield were measured. KEY RESULTS: The results confirmed the robustness of the root hair phenotypes in soils and their relationship to rhizosheath production. The data demonstrated that root hair length is important for shoot P accumulation and biomass, while only the presence of root hairs is critical for yield. Root hair presence was also critical for tolerance to extreme combined P deficit and drought stress, with genotypes with no root hairs suffering extreme growth retardation in comparison with those with root hairs. CONCLUSIONS: The results suggest that although root hair length is not important for maintaining yield, the presence of root hairs is implicit to sustainable yield of barley under P-deficient conditions and when combined with extreme drought. Root hairs are a trait that should be maintained in future germplasm.

Acidic fibroblast growth factor attenuates the cytotoxic effects of peroxynitrite in primary human osteoblast precursors.

BACKGROUND: Skeletal injury and associated ischemia and inflammation induce the generation of pro-oxidants such as peroxynitrite (ONOO-), which has been demonstrated to induce apoptosis in several cell lines. Fibroblast growth factor (FGF-1) is important for coordinating osteogenesis and angiogenesis of osseous repair. In vitro studies were performed examining the effect of FGF-1 on human osteoblast progenitor stromal stem (HSS) cell proliferation, differentiation, and response to ONOO-. METHODS: HSS cells were isolated and growth kinetics determined in the presence and absence of FGF-1. The effect of FGF-1 on HSS cell expression of osteoblast-specific osteopontin and osteocalcin mRNA and protein was examined by reverse transcriptase polymerase chain reaction and Western blot techniques. To determine the sensitivity of HSS cells to ONOO- in the absence and presence of FGF-1 pretreatment, cells were exposed to varying concentrations of the oxidant and examined for cell death using quantitative fluorescence staining with fluorescein diacetate and propidium diacetate. RESULTS: Treatment of HSS cells with FGF-1 significantly enhanced cellular growth rates by 5 days (4.6 x 105 cells/mL vs. 3.1 x 105 cells/mL) and induced expression of both osteopontin and osteocalcin mRNA and protein. Exposure of HSS cells to ONOO- resulted in a dose- and time-dependent delayed cell death that was more characteristic of apoptosis than necrosis. Pretreatment of HSS cells with FGF-1 prevented ONOO- mediated apoptosis. CONCLUSION: In vitro, treatment of HSS cells with FGF-1 stimulates cell growth and induces expression of differentiation markers specific to osteoblasts. FGF-1 treatment renders osteoblast precursors resistant to the cytotoxic effects of ONOO-. These results suggest that FGF-1 promotes the progression of bone repair mechanisms by increasing the population of osteoblasts and imparting protection to the cell line from the hostile inflammatory environment.

Molecular mechanisms of angiogenesis: experimental models define cellular trafficking of FGF-1.

Numerous studies have established that stimulation of cell growth by members of the fibroblast growth factor (FGF) family of polypeptides is dependent upon an extracellular pathway. Acidic FGF (FGF-1), however, lacks a classical signal sequence for secretion, thereby making it difficult to evaluate regulation of biological activity by this growth factor. Efforts in this laboratory have utilized molecular techniques of retrovirology and transgenic modeling to introduce cDNA sequences encoding either an intracellular or extracellular form of FGF-1 into primary diploid cells to examine trafficking and compartmentalization of FGF-1. Several lines of evidence obtained from these models provide a compelling argument that the stimulation of FGF-1-associated cellular transformation is restricted to an extracellular, receptor-mediated pathway, involving protein tyrosine phosphorylation and nuclear localization. In addition, an unconventional secretion pathway for intracellular FGF-1 has been identified that involves mechanisms associated with oxidative stress.

Molecular mechanisms of angiogenesis: experimental models define cellular trafficking of FGF-1

Numerous studies have established that stimulation of cell growth by members of the fibroblast growth factor (FGF) family of polypeptides is dependent upon an extracellular pathway. Acidic FGF (FGF-1), however, lacks a classical signal sequence for secretion, thereby making it difficult to evaluate regulation of biological activity by this growth factor. Efforts in this laboratory have utilized molecular techniques of retrovirology and transgenic modeling to introduce cDNA sequences encoding either an intracellular or extracellular form of FGF-1 into primary diploid cells to examine trafficking and compartmentalization of FGF-1. Several lines of evidence obtained from these models provide a compelling argument that the stimulation of FGF-1-associated cellular transformation is restricted to an extracellular, receptor-mediated pathway, involving protein tyrosine phosphorylation and nuclear localization. In addition, an unconventional secretion pathway for intracellular FGF-1 has been identified that involves mechanisms associated with oxidative stress

Serum-starvation induces the extracellular appearance of FGF-1.

Autocrine/paracrine stimulation of cell growth by members of the fibroblast growth factor (FGF) family of polypeptides is dependent upon extracellular interactions with specific high affinity receptors at the cell surface. Acidic FGF (FGF-1) lacks a classical signal sequence for secretion, suggesting that intrinsic levels of this mitogen may not stimulate cell growth and utilizes a non-classical pathway to gain access to the extracellular compartment. To evaluate the biological potential of intracellular FGF-1 more rigorously, human cDNA sequences for the growth factor were introduced into primary murine embryonic fibroblasts using retrovirally mediated gene transfer. Heparin affinity, Western analysis, mitogenic assays, in situ immunohistochemical techniques, induction of tyrosine phosphorylation and antibody inhibition studies were used to demonstrate functionality of the FGF-1 transgene in this experimental model. Under normal culture conditions, cells constitutively expressing intracellular FGF-1 exhibited a slight growth advantage. In contrast, when maintained in reduced serum, these cells adopted a transformed phenotype and demonstrated an enhanced growth potential, induction of FGF-specific phosphotyrosyl proteins and the nuclear association of the growth factor. Analysis of the conditioned media from these stressed cells indicated that serum starvation induces the secretion of FGF-1 as latent high molecular mass complexes requiring reducing agents to activate its full biological potential.

Fibroblast growth factor-induced motor end plate regeneration in atrophic muscle.

OBJECTIVE: To determine whether fibroblast growth factor 1 implanted with viable nerve into atrophic muscle will stimulate formation of functional, acetylcholine producing motor end plates. DESIGN: Twelve male Lewis rats underwent predenervation of the hamstring muscle 8 weeks before implantation of the nerve at a site distant from the original motor end plate. Six animals underwent implantation of the tagged nerve ending into atrophic muscle with 50 microgram of fibroblast growth factor 1 in a fibrin adhesive carrier (group 1). Three animals underwent implantation with nerve, fibrin adhesive, and no fibroblast growth factor 1 (group 2); and three animals underwent implantation with fibroblast growth factor 1 and fibrin adhesive with no nerve (group 3). Animals were killed 9 weeks after implantation and nerve and muscle specimens were harvested. MAIN OUTCOME MEASURES: Histoenzymologic methods for acetylcholinesterase and silver impregnation of nerve fibers were performed 9 weeks after fibroblast growth factor 1-fibrin adhesive implantation. Variables included the number of motor end plates per highpower field and motor end plate length. RESULTS: Robust axonal sprouting and formation of multiple motor end plates were found arborized in serial fashion equidistant around the implanted nerve ending. Rare extrasynaptic staining occurred. End plate lengths were significantly shorter in the fibroblast growth factor 1-treated muscles (group 1) than in the specimens without fibroblast growth factor 1 (group 2) (31.2 vs 58.5 micron; P>001, paired t test). The arborization of motor end plates, rare extrasynaptic staining, and shorter end plate lengths seen in group 1 were all consistent with mature motor end plates. Controls (group 3) displayed limited motor end plate formation and extensive extrasynaptic staining typical of denervation. CONCLUSION: This study presents encouraging evidence that fibroblast growth factor 1 with fibrin adhesive carrier can facilitate the reinnervation of atrophied muscle by enhancing the formation or revitalization of motor end plates. Future studies will address muscle function and use of different carrier materials.

Phase Ib trial of pentoxifylline and ciprofloxacin in patients treated with interleukin-2 and lymphokine-activated killer cell therapy for metastatic renal cell carcinoma.

The dose of interleukin 2 (IL-2) which can be administered to cancer patients is limited largely by a capillary leak syndrome. Pentoxifylline (PTX) is a methylxanthine which reduces IL-2 toxicity in animals. Ciprofloxacin (Cipro) modifies the metabolism of methylxanthines and, when coadministered with PTX, increases levels of PTX and certain of its metabolites. We conducted a phase Ib trial in patients receiving IL-2 and lymphokine-activated killer cell (LAK) cell therapy for metastatic renal cell carcinoma to identify the maximum tolerated dose of PTX which could be coadministered with Cipro in this setting. Eighteen patients received IL-2 (Roche) by continuous infusion at 6 x 10(6) units/m2/day on days 1-5 and underwent leukapheresis on days 7-9. LAK cells were infused on days 12-14. IL-2 was administered at 2 x 10(6) units/m2/day on days 10-20. Cohorts of patients received PTX at 2.5 (n = 3), 3.1 (n = 6), 3.9 (n = 6), and 4.9 (n = 3) mg/kg by 30 min i.v. infusion every 4 h on days 0-5 and 10-20 and Cipro (500 mg p.o. every 12 h) on days 1-5 and 10-20. Toxicity was compared with that observed in 33 historical control patients who received 37 cycles of an identical regimen of IL-2/LAK without PTX/Cipro. PTX at 2.5-3.9 mg/kg and Cipro were well tolerated. The maximum tolerated dose of PTX was 3.9 mg/kg. Dose-limiting emesis (n = 1) and atrial fibrillation (n = 2) occurred at 4.9 mg/kg and were reversible. Two complete, one partial and one minor, responses were observed. Patients treated with 3.9 mg/kg PTX received 95.0% of the planned dose of IL-2 as compared to 72.8% in the control patients (P < 0.025), primarily due to a lower incidence of azotemia and metabolic acidosis in PTX/Cipro recipients than had been seen in the historical control patients. The results of this study demonstrate that PTX/Cipro can be administered to patients receiving IL-2/LAK without apparent loss of therapeutic efficacy. Moreover, PTX/Cipro recipients exhibited less toxicity than historical controls. Therefore, treatment with PTX/Cipro may allow delivery of higher doses of IL-2, which might induce more responses in IL-2-responsive tumors and regression of tumors unresponsive to conventional doses of IL-2.

Lymphokine-activated killer (LAK) precursor cell activity is present in infused peripheral blood stem cells and in the blood after autologous peripheral blood stem cell transplantation.

Immunotherapy with interleukin-2 (IL-2) early after peripheral blood stem cell transplantation (PBSCT) is being considered as a potential way to eradicate minimal residual disease. The aim of this study was to determine whether lymphocytes which can acquire lymphokine-activated killer (LAK) cell activity are present in PBSC and in the blood of patients after PBSCT. Fresh and cryopreserved G-CSF-mobilized PBSC from eight patients were incubated with IL-2 (1000 U/ml) for 3-6 days and then tested for LAK activity as measured by lysis of the Daudi cell line. LAK activity was present in both fresh and cryopreserved PBSC, with mean lysis of 32% and 36%, respectively, at an effector:target (E:T) ratio of 50:1. To assess the reconstitution of LAK precursor activity after PBSCT, peripheral blood (PB) obtained from eight other patients 15-60 days after PBSCT was similarly tested. LAK activity was detected in PB from every patient (mean lysis of 38% at an E:T ratio of 12.5:1). PB from patients after PBSCT contained a higher percentage of CD8+ cells and CD56+ cells than did PB from 9 normal controls (47.2% vs. 21.4% CD8+ cells, P < 0.005 and 28.6% vs. 8.6% CD56+ cells, P < 0.0005). Moreover, PB from 4 of 5 patients tested after PBSCT exhibited a high percentage of cells expressing p75, the intermediate affinity IL-2R. Thus, precursor cells capable of acquiring IL-2-inducible LAK activity are present in PBSC and are rapidly reconstituted after PBSCT. The findings provide a rationale for testing IL-2 as a way of decreasing relapses after PBSCT.

Therapy for painful cutaneous leiomyomas.

Cutaneous leiomyomas, if multiple and painful, can pose a treatment dilemma. The types of cutaneous leiomyomas and the anatomy and physiology of smooth muscle are reviewed as an introduction to the therapy of painful leiomyomas by a calcium-channel blocker.

Potent contact allergen in the rubber plant guayule (Parthenium argentatum).

Chemical and dermatotoxicological investigations of the natural and processed resin of the Mexican rubber plant, guayule (Parthenium argentatum), has established the presence of a sesquiterpene cinnamic acid ester (guayulin A) that is a potent elicitor of allergic contact dermatitis in experimental animals. The guayule contact allergen is comparable to the poison ivy skin allergens as an elicitor of dermatitis in sensitized guinea pigs.