Failure of recombinant human interleukin-3 therapy to induce erythropoiesis in patients with refractory Diamond-Blackfan anemia [see comments]

In two previous studies, we observed that recombinant human interleukin- 3 (IL-3) induced an increase in marrow burst-forming unit-erythroid- derived colonies in vitro in some patients with Diamond-Blackfan anemia (DBA). To determine whether a similar erythropoietic response could be induced in vivo, we treated 13 patients with DBA (aged 4 to 19 years) with two preparations of IL-3. All patients had absent absolute reticulocyte counts and markedly reduced to absent recognizable bone marrow erythroid elements; patients with circulating reticulocytes in the previous 12 months were excluded from study. All patients except 1 had failed steroid therapy and had been transfusion-dependent since infancy; 1 patient was maintained on high-dose prednisone at the time of enrollment. On the first arm of the study, IL-3 (Immunex Corp, Seattle, WA) was administered subcutaneously using a dose escalation regimen of 125 to 500 micrograms/m2/day in divided dosage at 12-hour intervals, coadministered with 1.5 mg/kg/d of oral ferrous sulphate. Of the 13 patients that entered the trial, 4 stopped prematurely because of adverse side effects. In the other 9 evaluable cases, reticulocytes increased transiently in 1 patient from 0 to 65 x 10(9)/L after 35 days of IL-3 therapy at 250 micrograms/m2, but transfusion dependency persisted. One transient peak in absolute reticulocyte count was noted in 6 other patients, but no erythroid response was observed after completion of a full course of IL-3. Oral prednisone at 0.5 mg/kg/d was then coadministered with IL-3 at 500 micrograms/m2 to 5 of the patients without effect, and treatment was stopped. In 2 patients, a second preparation of IL-3 (Sandoz Canada Inc, Dorval, Quebec, Canada) was initiated in a dose escalation regimen of 2.5 to 10 micrograms/kg and was coadministered with ferrous sulphate. No erythroid response was observed in either patient, and in one of the two, alternate-day subcutaneous recombinant erythropoietin at 300 U/kg was administered for 3 weeks in combination with daily IL-3 at 10 micrograms/kg, but no increased erythropoiesis was seen. Significant increases in white blood cell and eosinophil counts during administration of both preparations of IL-3 were observed in all patients. These data show that the response of DBA patients to IL-3 in vivo is heterogeneous and cannot be predicted from in vitro studies. The absence of a corrective effect of IL-3 in these patients with DBA indicates that a deficiency of the cytokine is not central in the pathogenesis of the disorder.     

Diamond-Blackfan anemia: promotion of marrow erythropoiesis in vitro by recombinant interleukin-3

To clarify the defective erythropoiesis in eight patients with Diamond- Blackfan anemia, we studied their bone marrow response in vitro to recombinant human interleukin-3 (IL-3) and recombinant granulocyte- macrophage colony-stimulating factor (GM-CSF). In an erythropoietin- containing assay system, specimens from six of the eight patients yielded low numbers of erythroid colonies compared to control values, and in five of these no erythropoietin dose-response could be elicited. Addition of IL-3, GM-CSF or both to cultures from the six patients had no effect on CFU-E-derived colonies. In contrast, IL-3 but not GM-CSF induced a marked increase in the number (183%) and size of the BFU-E- derived colonies in five of the six cases and partially corrected the impaired dose-response to erythropoietin in four. Bone marrow from the other two patients yielded numbers of CFU-E and BFU-E colonies comparable to controls and manifested similar increments in colonies with increasing concentrations of erythropoietin. When IL-3 was added to these cultures, further increments were observed in the number and size of BFU-E colonies. We conclude that IL-3 enhanced the marrow erythropoiesis in most of the patients and exerted a corrective effect on the aberrant colony formation in the presence of erythropoietin. The data raise the possibility of IL-3 as a therapeutic agent in Diamond- Blackfan anemia.     

Predictability of pharyngeal airway space dimension changes after orthognathic surgery in class II patients: A mathematical approach

IntroductionAngle Class II malocclusion due to mandibular retrognathia is a common dentofacial deformity. It is well known that mandibular advancement increases pharyngeal airway dimensions. The aim of this study was to evolve a mathematical method for predicting posterior pharyngeal airway space (PAS) changes based on 2D lateral cephalographic radiographs (LCRs) and expected extent of mandibular advancement prior to BSSO.Materials and methodsLinear regression analyses were performed in order to investigate the relation between the posterior airway space and mandibular advancement. LCRs where carried out to assess skeletal landmarks and pharyngeal airway space pre- (T0) and postoperatively (T1). To detect changes postoperatively, the posterior airway space was divided into three units: nasopharyngeal airway space (superior airway space — SPAS), oropharyngeal airway space (mid airway space — MAS) and hypopharyngeal airway space (inferior airway space — IAS). The differences between the distances of distinct measurement points (DIFF) were measured pre- and postoperatively. DOA referred to the distance of mandibular advancement and DP to the distance between the measurement points preoperatively. The parameters a, b₁ and b₂ were the regression coefficients that were determined separately for each unit (SPAS, MAS, and IAS).Results49 patients (16 male and 33 female) with a mean age of 27.2 years (SD: 10.09), ranging from 18 to 51 years, who underwent mandibular advancement surgery (BSSO) were enrolled in this study. The mean distance of mandibular advancement was 5.05 mm (SD: 1.63). Regarding SPAS and IAS, mandibular advancement did not affect dimensions significantly: SPAS DIFF, 0.33 mm ± 1.13 mm (b₁, p = 0.0881; b₂, p = 0.087); IAS DIFF, 0.66 mm ± 2.45 mm (b₁, p = 0.342; b₂, p = 0.765). DOA and DP did not influence DIFF significantly in both sections. Regarding MAS, the mean effect of mandibular advancement was an expansion of 2.47 mm ± 2.24. The linear regression model showed a statistically significant (b₁, p = 0.0064; b₂, p = 0.0240) influence of DOA and DP on DIFF in posterior airway dimensions pre- and postoperatively.DiscussionBased on preoperative LCR imaging data, a linear regression model was developed as a mathematical approach to allow prediction of PAS development in patients with Angle Class II malocclusions of different degrees. Increasing mandibular advancement was shown to be linked to increasing PAS, while a greater distance between the measuring points preoperatively led to smaller predicted PAS increases postoperatively.ConclusionPredicting pharyngeal airway space (PAS) development after mandibular advancement by analysing lateral cephalometric radiographs (LCR) may be useful in the screening and treatment of obstructive sleep apnea syndrome (OSAS) patients. Our mathematical approach is a simple and sustainable prediction tool based on LTR data for patients with Class II malocclusions.     

Inhibition of hepatic scavenger receptor-class B type I by RNA interference decreases atherosclerosis in rabbits

ObjectiveScavenger receptor-class B type I (SR-BI), the receptor for HDL-cholesterol, plays a key role in HDL metabolism, whole body cholesterol homeostasis, and reverse cholesterol transport. We investigated the in vivo impact of hepatic SR-BI inhibition on lipoprotein metabolism and the development of atherosclerosis employing RNA interference.MethodsSmall hairpin RNA plasmid specific for rabbit SR-BI was complexed with galactosylated poly-l-lysine, allowing an organ-selective, receptor-mediated gene transfer. Rabbits were fed a cholesterol-rich diet, and were injected with plasmid-complexes once a week.ResultsAfter 2 weeks of treatment hepatic SR-BI mRNA levels were reduced by 80% accompanied by reduced SR-BI protein levels and a modulation of the lipoprotein profile. Rabbits treated with SR-BI-specific plasmid-complexes displayed higher cholesteryl ester transfer from HDL to apoB-containing lipoproteins, lower HDL-cholesterol, and higher VLDL-cholesterol levels, when compared to controls. In a long-term study, this gene therapeutic intervention led to a similar modulation of the lipoprotein profile, to lower total cholesterol levels, and most importantly to a 50% reduction of the relative atherosclerotic lesion area.ConclusionOur results are another indication that the role of SR-BI in lipoprotein metabolism and atherogenesis in rabbits – a CETP-expressing animal model displaying a manlike lipoprotein profile may be different from the one found in rodents.     

Climate change and the selective signature of the Late Ordovician mass extinction

Selectivity patterns provide insights into the causes of ancient extinction events. The Late Ordovician mass extinction was related to Gondwanan glaciation; however, it is still unclear whether elevated extinction rates were attributable to record failure, habitat loss, or climatic cooling. We examined Middle Ordovician-Early Silurian North American fossil occurrences within a spatiotemporally explicit stratigraphic framework that allowed us to quantify rock record effects on a per-taxon basis and assay the interplay of macrostratigraphic and macroecological variables in determining extinction risk. Genera that had large proportions of their observed geographic ranges affected by stratigraphic truncation or environmental shifts at the end of the Katian stage were particularly hard hit. The duration of the subsequent sampling gaps had little effect on extinction risk, suggesting that this extinction pulse cannot be entirely attributed to rock record failure; rather, it was caused, in part, by habitat loss. Extinction risk at this time was also strongly influenced by the maximum paleolatitude at which a genus had previously been sampled, a macroecological trait linked to thermal tolerance. A model trained on the relationship between 16 explanatory variables and extinction patterns during the early Katian interval substantially underestimates the extinction of exclusively tropical taxa during the late Katian interval. These results indicate that glacioeustatic sea-level fall and tropical ocean cooling played important roles in the first pulse of the Late Ordovician mass extinction in Laurentia.