A concise review of glycerol derivatives for use as fuel additives.

Due to renewable fuel mandates worldwide, the increase in biodiesel production has caused an oversupply of low-cost glycerol on the markets, which can negatively affect the sustainability of the biodiesel industry as a whole. In order to avoid that scenario, the transformation of glycerol into value-added products has been investigated, and the production of additives for internal combustion engine fuels is one good example of glycerol valorization. The present work presents a summary of the literature describing the most important chemical pathways through which glycerol can be converted into fuel additives, to be subsequently mixed with either gasoline, biodiesel, or diesel fuel. The focus is on the three major categories, namely glycerol acetals/ketals, ethers, and esters (acetates). Moreover, the effectiveness of the different glycerol-derived compounds is illustrated through several examples from the literature. Finally, a few research gaps on the topic are identified and suggestions for future work are described.

Pulmonary fibrosis is associated with an elevated risk of thromboembolic disease.

Recent epidemiological studies have suggested an increased risk of venous thromboembolism (VTE) in lung fibrosis. Large-scale epidemiological data regarding the risk of VTE in pulmonary fibrosis-associated mortality have not been published. Using data from the National Center for Health Statistics from 1988-2007, we determined the risk of VTE in decedents with pulmonary fibrosis in the USA. We analysed 46,450,489 records, of which 218,991 met our criteria for idiopathic pulmonary fibrosis. Among these, 3,815 (1.74%) records also contained a diagnostic code for VTE. The risk of VTE in pulmonary fibrosis decedents was 34% higher than in the background population, and 44% and 54% greater than among decedents with chronic obstructive pulmonary disease and lung cancer, respectively. Those with VTE and pulmonary fibrosis died at a younger age than those with pulmonary fibrosis alone (females: 74.3 versus 77.4 yrs (p<0.0001); males: 72.0 versus 74.4 yrs (p<0.0001)). Decedents with pulmonary fibrosis had a significantly greater risk of VTE. Those with VTE and pulmonary fibrosis died at a younger age than those with pulmonary fibrosis alone. These data suggest a link between a pro-fibrotic and a pro-coagulant state.

Soil texture and climate limit cultivation of the arsenic hyperaccumulator Pteris vittata for phytoextraction in a long-term field study.

Long term field studies are required to bridge gaps between research and practical application of arsenic phytoextraction with the arsenic-hyperaccumulating fern Pteris vittata. In a 4-year field study, we investigated the effects of nutrient application (compost, inorganic or organic nitrogen, inorganic or organic phosphorus) and soil texture (13 % and 35 % clay) on arsenic phytoextraction with P. vittata in moderately contaminated soils (74-79 mg As/kg in the 0-15 cm depth interval). We found the highest phytoextraction rates, 5 ± 1 kg As/ha/y, in a coarse-textured compost-amended soil after 2 years of phytoextraction. Phytoextraction rates decreased over time, likely due to decreased root growth in mature stands, indicating plants should be replaced every 2-3 years to maintain phytoextraction efficiency. Across soil textures, nitrogen or phosphorus application led to a 60 % decrease in mean frond arsenic concentrations, leading to mean phytoextraction rates 54 % lower than in control ferns. In the fine-textured soil, frond arsenic concentrations were 54 % lower than in the coarse-textured soil, and fewer ferns survived from year 3 to 4. Across soil textures, compost application increased fern survival. We show that phytoextraction with P. vittata is limited to specific soil and climate conditions, narrower than those under which P. vittata grows in the wild.

Syntaxin 4, VAMP2, and/or VAMP3/cellubrevin are functional target membrane and vesicle SNAP receptors for insulin-stimulated GLUT4 translocation in adipocytes.

Introduction of the cytoplasmic domain of syntaxin 4, using either recombinant vaccinia virus or single-cell microinjection, resulted in an inhibition of insulin-stimulated GLUT4 but not GLUT1 translocation to the plasma membrane. This was specific for syntaxin 4, since neither the expression of syntaxin 3 nor the expression of a syntaxin 4 mutant in which the vesicle-associated membrane protein (VAMP) binding site was deleted had any significant effect. Consistent with the requirement for a functional VAMP binding site, expression of the cytoplasmic domains of VAMP2 or VAMP3/cellubrevin also resulted in an inhibition of insulin-stimulated GLUT4 translocation. In addition, immunoprecipitation of the expressed syntaxin 4 cytoplasmic domain resulted in an insulin-stimulated increase in the coimmunoprecipitation of GLUT4-containing vesicles. Together, these data demonstrate that syntaxin 4, VAMP2, and/or VAMP3/cellubrevin can function as target membrane and vesicle SNAP receptors, respectively, for insulin-responsive GLUT4 translocation to the plasma membrane.

Osmotic shock inhibits insulin signaling by maintaining Akt/protein kinase B in an inactive dephosphorylated state.

We have previously reported that insulin and osmotic shock stimulate an increase in glucose transport activity and translocation of the insulin-responsive glucose transporter isoform GLUT4 to the plasma membrane through distinct pathways in 3T3L1 adipocytes (D. Chen, J. S. Elmendorf, A. L. Olson, X. Li, H. S. Earp, and J. E. Pessin, J. Biol. Chem. 272:27401-27410, 1997). In investigations of the relationships between these two signaling pathways, we have now observed that these two stimuli are not additive, and, in fact, osmotic shock pretreatment was found to completely prevent any further insulin stimulation of glucose transport activity and GLUT4 protein translocation. In addition, osmotic shock inhibited the insulin stimulation of lipogenesis and glycogen synthesis. This inhibition of insulin-stimulated downstream signaling occurred without any significant effect on insulin receptor autophosphorylation or tyrosine phosphorylation of insulin receptor substrate 1 (IRS1). Furthermore, there was no effect on either the insulin-stimulated association of the p85 type I phosphatidylinositol (PI) 3-kinase regulatory subunit with IRS1 or phosphotyrosine antibody-immunoprecipitated PI 3-kinase activity. In contrast, osmotic shock pretreatment markedly inhibited the insulin stimulation of protein kinase B (PKB) and p70S6 kinase activities. In addition, the dephosphorylation of PKB was prevented by pretreatment with the phosphatase inhibitors okadaic acid and calyculin A. These data support a model in which osmotic shock-induced insulin resistance of downstream biological responses results from an inhibition of insulin-stimulated PKB activation.

Human GLUT4/muscle-fat glucose-transporter gene. Characterization and genetic variation.

Four overlapping DNA fragments spanning 32 kb containing the human GLUT4 facilitative glucose-transporter gene were isolated and characterized. The sequence of the GLUT4 gene (approximately 6.3 kb) and 2.0 kb of the promoter region was determined. The sequence of the promoter revealed potential binding sites for transcription factors known to regulate gene expression in muscle cells and adipocytes. However, transfection of constructs including 2 kb of the GLUT4 promoter fused to the bacterial CAT gene into 3T3-L1 adipocytes displayed only weak promoter activity. Because insulin resistance plays a prominent role in the development of NIDDM, genetic variation in the sequence of GLUT4 also was evaluated. Oligonucleotide primer pairs were selected that allowed the protein-coding region of the human GLUT4 gene to be amplified by PCR. The sequence of the protein-coding region of the GLUT4 gene and all intron-exon junctions was determined for a single diabetic Pima Indian and was identical to that of the cloned gene and cDNA. SSCP analysis was used to screen patients with diabetes mellitus and normal, healthy nondiabetic individuals for mutations at the GLUT4 locus. In addition to the silent substitution in the codon for Asn130 (AAC or AAT) and a Val383 (GTC)-->Ile(ATC) replacement described previously, two new variants were identified. One was a T-->A substitution in intron 1 that was found in 1 of 36 NIDDM patients who were typed for this variant. The second was a Ile385(ATT)-->Thr(ACT) replacement that occurred in 1 normal individual and was not found in any of 676 other normal and diabetic subjects. A large and racially diverse group of normal and diabetic individuals also was screened for the Ile383 polymorphism. It occurred in both diabetic and nondiabetic subjects. There is no indication from our data that these polymorphisms are associated with NIDDM.

Umbilical cord blood graft engineering: challenges and opportunities.

We are entering a very exciting era in umbilical cord blood transplantation (UCBT), where many of the associated formidable challenges may become treatable by ex vivo graft manipulation and/or adoptive immunotherapy utilizing specific cellular products. We envisage the use of double UCBT rather than single UCBT for most patients; this allows for greater ability to treat larger patients as well as to manipulate the graft. Ex vivo expansion and/or fucosylation of one cord will achieve more rapid engraftment, minimize the period of neutropenia and also give certainty that the other cord will provide long-term engraftment/immune reconstitution. The non-expanded (and future dominant) cord could be chosen for characteristics such as better HLA matching to minimize GvHD, or larger cell counts to enable part of the unit to be utilized for the development of specific cellular therapies such as the production of virus-specific T-cells or chimeric-antigen receptor T-cells which are reviewed in this study.

Regulation of c-fos expression in adipose and muscle tissue of diabetic rats.

Insulin treatment of control rats demonstrated a marked 8-fold transient increase (15 min) in c-fos mRNA in white adipose tissue, which returns to basal levels by 5 h. Similarly, insulin treatment resulted in a rapid 9-fold increase in cardiac muscle c-fos mRNA, which also returned to control values by 1 h. By contrast, insulin treatment resulted in only a small increase in c-jun mRNA levels in both adipose tissue and cardiac muscle. Similarly, the expression of c-jun mRNA was only slightly responsive to insulin in these tissues from streptozocin-induced insulin-deficient diabetic rats. However, insulin treatment of insulin-deficient diabetic rats resulted in a prolonged increase in c-fos message levels in adipose tissue without any significant change in the time course of c-fos mRNA induction/repression in cardiac muscle. These data demonstrate that in contrast to c-jun, c-fos is transiently increased in both cardiac muscle and adipose tissue by insulin treatment. Furthermore, transrepression of the c-fos gene is specifically attenuated in adipose tissue of insulin-deficient diabetic rats, but not in cardiac muscle.

Expression of a prenylation-deficient Rab4 interferes with propagation of insulin signaling through insulin receptor substrate-1.

Rab proteins are small GTP-binding proteins of the Ras superfamily that function in the regulation of vesicle transport processes. The Rab4 isoform has been implicated in insulin action. For instance, overexpression of a prenylation-deficient form of Rab4 has been shown to inhibit insulin-dependent GLUT4 translocation. Other steps affected by Rab4 in the cascade of events resulting from insulin receptor activation have not been elucidated. In the present studies, we measured effects on insulin-signaling proteins in 3T3-L1 adipocytes transiently expressing cytoplasmic forms of Rab4 and Rab5. Expression of a mutant Rab4 lacking a prenylation site resulted in reduced insulin-dependent phosphorylation ofcytoplasmic and internal membrane-associated insulin receptor substrate-1, leading to decreased insulin receptor substrate-1-associated phosphatidylinositol 3'-OH kinase activation and decreased Akt activation. These effects were not observed upon introduction of a similar mutant form of Rab5. These data indicate that Rab4 or a Rab4-associated protein is involved at one or more steps in propagating the insulin signal, in addition to any role it may play in the regulation of GLUT4 vesicle translocation. Our results support models of insulin signaling in which regulation of internal membrane trafficking plays a role in transduction of the insulin signal.

Characterization of 5'-heterogeneity of the rat GLUT4/muscle-adipose glucose transporter gene product.

To examine the mechanisms responsible for tissue-specific, nutritional, and metabolic regulation of the GLUT4/muscle-adipose specific glucose transporter, we isolated and characterized the properties of the rat GLUT4 gene. Examination of the sequenced 2.5-kilobase flanking DNA revealed substantial identity with that of the mouse and human GLUT4 genes, with the greatest degree of sequence identity within the proximal 1000 basepairs up-stream of the GLUT4 open reading frame. Primer extension analysis identified a unique single transcription initiation site 176 basepairs up-stream from the start of translation. However, ribonuclease mapping revealed the presence of a previously undescribed alternatively spliced form of GLUT4 messenger RNA. Approximately 75% of the GLUT4 transcripts consisted of a fully spliced messenger RNA, and 25% was expressed as an unspliced intron-containing species. The ratios of 5' spliced and unspliced messages were invariant in adipose, cardiac, and skeletal muscle tissues. In vitro translation of reporter constructs containing both the spliced and unspliced leader demonstrated a functional difference between these two transcripts, with the unspliced form translated approximately 5-fold more than the fully spliced species. These data demonstrate the presence of 5'-heterogeneity of the GLUT4 transcripts, which underlies differences in translational efficiency in vitro.

Low carnitine intake and altered lipid metabolism in infants.

We examined the effect of dietary carnitine on variables of lipid metabolism in human infants. Normal male full-term infants were fed an isolated soy-protein-based formula with or without added carnitine from age 6-9 d to age 112 d. Growth and food intake were measured throughout the study. At ages 56 and 112 d serum concentrations of carnitine, free fatty acids, and triglycerides and urinary excretion of carnitine and medium-chain dicarboxylic acids were measured. Serum carnitine concentrations were lower in all infants fed unsupplemented formula. There was no difference in growth or food intake between the two groups of infants. Serum free fatty acid concentrations were significantly higher in the infants not receiving dietary carnitine. Moreover, excretion of all three medium-chain dicarboxylic acids was significantly higher in infants not receiving dietary carnitine. We conclude that lack of dietary carnitine affects lipid metabolism of infants during the first 4 mo of life.

Carnitine status of lactoovovegetarians and strict vegetarian adults and children.

Because carnitine is contained primarily in meats and dairy products, vegetarian diets provide a model for assessing the impact of prolonged low carnitine intake on carnitine status. Plasma carnitine concentrations and urinary carnitine excretion were measured in adults and children consuming a strict vegetarian, lactoovovegetarian, or mixed diet. In adults plasma carnitine concentration and urinary carnitine excretion of strict vegetarians and lactoovovegetarians were significantly lower than those in the mixed-diet group but were not different from each other. In children significant differences were found between all three diet groups for both plasma carnitine concentration and urinary carnitine excretion. The differences in plasma carnitine concentrations were greater in children than in adults, possibly reflecting the effects of growth and tissue deposition. Small differences between diet groups in adults do not suggest a nutritionally significant difference in carnitine status. Whether vegetarian children are at greater risk for overt deficiency is not answered.

Depressive symptoms and work role satisfaction in mothers of toddlers.

OBJECTIVE: To determine the incidence of depressive symptoms in mothers of toddlers in community pediatric practice. The interaction of employment and work role satisfaction with depressive symptoms was also investigated. SUBJECTS AND METHODS: Depression screening measures were completed by 233 mothers of toddlers (aged 12 to 24 months) at health supervision visits in two community pediatric practices in New Hampshire. Depression was evaluated with a depressive symptom screening inventory modified by Barrett, Oxman, and Gerber from the Hopkins Symptom Checklist for use in primary care population. Data were obtained on parents' socioeconomic variables, hours worked, and whether the mother was satisfied with her current role of being employed or not employed. RESULTS: Depressive symptoms were present in 42% of mothers. Rates of depressive symptoms were similar in employment groups but varied significantly with work role satisfaction. When both employment and satisfaction were considered, mothers who were dissatisfied were 3.7 times more likely to be depressed. After controlling for work role satisfaction, mothers working part time were half as likely to be depressed as mothers working full time and not employed. CONCLUSION: Depressive symptoms are a major problem for mothers of toddlers in middle class pediatric practice. Work role satisfaction and employment status together are related to depressive symptoms.

A national general pediatric clerkship curriculum: the process of development and implementation.

OBJECTIVE: To describe a new national general pediatrics clerkship curriculum, the development process that built national support for its use, and current progress in implementing the curriculum in pediatric clerkships at US allopathic medical schools. CURRICULUM DEVELOPMENT: A curriculum project team of pediatric clerkship directors and an advisory committee representing professional organizations invested in pediatric student education developed the format and content in collaboration with pediatric educators from the Council on Medical Student Education in Pediatrics (COMSEP) and the Ambulatory Pediatric Association (APA). An iterative process or review by clerkship directors, pediatric departmental chairs, and students finalized the content and built support for the final product. The national dissemination process resulted in consensus among pediatric educators that this curriculum should be used as the national curricular guideline for clerkships. MONITORING IMPLEMENTATION: Surveys were mailed to all pediatric clerkship directors before dissemination (November 1994), and in the first and third academic years after national dissemination (March 1996 and September 1997). The 3 surveys assessed schools' implementation of specific components of the curriculum. The final survey also assessed ways the curriculum was used and barriers to implementation. OUTCOMES: The final curriculum provided objectives and competencies for attitudes, skills, and 18 knowledge areas of general pediatrics. A total of 216 short clinical cases were also provided as an alternative learning method. An accompanying resource manual provided suggested strategies for implementation, teaching, and evaluation. A total of 103 schools responded to survey 1; 84 schools to survey 2; and 85 schools responded to survey 3 from the 125 medical schools surveyed. Before dissemination, 16% of schools were already using the clinical cases. In the 1995-1996 academic year, 70% of schools were using some or all of the curricular objectives/competencies, and 45% were using the clinical cases. Two years later, 90% of schools surveyed were using the curricular objectives, 88% were using the competencies, 66% were using the clinical cases. The extent of curriculum use also increased. Schools using 11 or more of the 18 curriculum's knowledge areas increased from 50% (1995-1996) to 73% (1996-1997). CONCLUSION: This new national general pediatric clerkship curriculum developed broad support during its development and has been implemented very rapidly nationwide. During this period the COMSEP and the APA have strongly supported its implementation with a variety of activities. This development and implementation process can be a model for other national curricula.

Prevention and therapy of serous otitis media by oral decongestant: a double-blind study in pediatric practice.

We studied the efficacy of (1) preventing the development of serous otitis media (SOM) by using an oral decongestant in children with acute otitis media and (2) treating SOM with an oral decongestant. In a randomized double-blind study, 190 children were treated for acute otitis media with antibiotics and either pseudoephedrine hydrochloride (Sudafed) or placebo. They were evaluated two weeks later by tympanometry and (independently) by clinical evaluation and pneumotoscopy. There were no significant differences between the two groups, except that males developed SOM significantly more often than did females. Use of decongestant and placebo was continued in 78 patients with SOM for up to four more weeks. Again, there were no siginificant differences between the treatment groups except that patients with an allergic history did significantly worse using a decongestant. Overall there was no benefit from pseudoephedrine in either the prevention or treatment of SOM.

Regulation of glucose transporters GLUT-4 and GLUT-1 gene transcription in denervated skeletal muscle.

Because GLUT-4 expression is decreased whereas GLUT-1 expression is increased in denervated skeletal muscle, we examined the effects of denervation on GLUT-4 and GLUT-1 gene transcription. The right hindlimb skeletal muscle of male transgenic mice containing sequential truncations (2,400, 1,639, 1,154, and 730 bp) of the human GLUT-4 promoter linked to the chloramphenacol acyl transferase (CAT) gene was denervated, and the contralateral hindlimb was sham operated. RNase protection analysis revealed that after 72 h denervation decreased CAT mRNA and GLUT-4 mRNA levels 64-85%, respectively (P < 0.05), in the gastrocnemius muscles. In contrast, denervation of the right hindlimb of male rats increased GLUT-1 gene transcription and GLUT-1 mRNA levels by 94 and 213%, respectively (P < 0.05). In conclusion, GLUT-4 transcription is decreased but GLUT-1 transcription is increased in denervated skeletal muscle, suggesting that the effects of denervation on GLUT-4 and GLUT-1 expression are, in part, transcriptionally mediated. Furthermore, these data indicate that a DNA sequence regulated by denervation is located within 730 bp of the 5'-flanking promoter region of the human GLUT-4 gene.

Regulation of muscle GLUT-4 transcription by AMP-activated protein kinase.

Skeletal muscle GLUT-4 transcription in response to treatment with 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR), a known activator of AMP-activated protein kinase (AMPK), was studied in rats and mice. The increase in GLUT-4 mRNA levels in response to a single subcutaneous injection of AICAR, peaked at 13 h in white and red quadriceps muscles but not in the soleus muscle. The mRNA level of chloramphenicol acyltransferase reporter gene which is driven by 1,154 or 895 bp of the human GLUT-4 proximal promoter was increased in AICAR-treated transgenic mice, demonstrating the transcriptional upregulation of the GLUT-4 gene by AICAR. However, this induction of transcription was not apparent with 730 bp of the promoter. In addition, nuclear extracts from AICAR-treated mice bound to the consensus sequence of myocyte enhancer factor-2 (from -473 to -464) to a greater extent than from saline-injected mice. Thus AMP-activated protein kinase activation by AICAR increases GLUT-4 transcription by a mechanism that requires response elements within 895 bp of human GLUT-4 proximal promoter and that may be cooperatively mediated by myocyte enhancer factor-2.

Reversal of flow in the left pulmonary artery after cavopulmonary connection.

The postoperative course of a 15-month-old girl who underwent a bilateral bidirectional cavopulmonary connection was complicated by a left chylothorax and left hemidiaphragm paralysis. Two-dimensional and Doppler echocardiography revealed complete flow reversal in the left pulmonary artery. This flow abnormality was confirmed by angiography. Multiple aortopulmonary collaterals had also developed and were coil embolized at the time of catheterization. Coil embolization of the collaterals, combined with relief of the chylothorax and diaphragmatic plication, reestablished forward flow in the left pulmonary artery.

Renal conservation of carnitine by infants and adults: no evidence of developmental regulation.

To determine the efficiency of renal conservation of carnitine in infants, urinary carnitine excretion was measured at intervals in 10 infants while plasma carnitine concentration was manipulated by supplementing carnitine-free formula with 0 microM, 140 microM and 280 microM L-carnitine. As carnitine supplementation increased from 0 microM to 280 microM, fractional excretion of free carnitine increased tenfold from 0.6% to 6.0%; fractional excretion of acylcarnitine esters increased to a lesser degree (10.5-15.6%). At all supplementation levels fractional excretion of acylcarnitine esters was significantly greater than fractional excretion of free carnitine. We conclude that free and esterified carnitine are handled differently in the infant kidney. Results in infants were compared to previously reported data for adults. Mean fractional excretions of total, free and esterified carnitine by infants (7.2%, 5.4% and 12.7%, respectively) were similar to those by adults (6.5%, 5.0% and 15.0%). Thus, renal losses of carnitine apparently do not account for the low plasma carnitine concentrations observed in infants fed carnitine-free formulas.

Model system of ongoing care for native Americans--a 5-year followup.

In 1979, continuing care from a personal physician was identified as a priority at the Indian Health Service site in Zuni, NM, a rural hospital and ambulatory care center serving 7,000 Zuni people. To encourage such care, a system was established that assigned each patient to a regular physician and organized physicians into teams. Three teams, each consisting of three clinicians and other support personnel, served specific geographic regions of the village. Five years later, the ongoing care provided for active randomly selected prenatal, diabetic, and general clinic patients was evaluated. The physician staff of the site had gone through a complete turnover during the previous five years. Based on a chart review for the year prior to patient identification, patients saw their regular physician from 48 to 61 percent of the time in all their visits, and their regular physician or his or her team colleague from 71 to 82 percent of the time in all their visits. Ongoing care from a personal physician or close colleague can be achieved in the Indian Health Service. Organization of physicians into teams appeared to be the critical element in promoting ongoing care at this site where physician turnover is high. Team physicians seldom all leave at once, and ongoing care as a priority is passed on by the attitude of other team physicians, by transfer of specific patients, and by patient expectation. Given the established benefits, ongoing care from a personal provider should be encouraged in the Indian Health Service as in other primary care settings.