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.

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.

Clinical trials and tribulations--lessons from pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a dreadful disease that lacks adequate therapy. A number of treatment trials have been performed and have utilized a variety of primary efficacy endpoints. Endpoints that provide the most useful efficacy information are clinical endpoints that are directly related to how a patient feels, functions or survives. Unfortunately, there are no properly established patient-reported outcome measures or measures of functional status in IPF, making survival the most robust primary efficacy endpoint. Clinically meaningful events such as hospitalization can also provide important efficacy information. The use of non-validated surrogate endpoints as primary outcome measures often leads to uncertainty when interpreting trial results.

P5-19-11: Tesetaxel, an Oral Taxane, as First-Line Therapy for Women with Metastatic Breast Cancer

Background

Parenteral taxanes (docetaxel, paclitaxel) are among the most active agents in treating metastatic breast cancer (MBC). However, their use is limited by inherent or acquired multidrug resistance, hypersensitivity, and neurotoxicity. Tesetaxel is an advanced-generation, orally available taxane that is formulated as a capsule for oral administration and has a long terminal half-life in plasma (∼180 hrs). Unlike standard taxanes, tesetaxel is not a substrate for P-glycoprotein (P-gp), a major cause of taxane resistance. The drug is highly concentrated in cells that overexpress P-gp. In taxane-resistant breast cancer xenografts (DU4475), tesetaxel induced a 94% reduction in tumor size, substantially exceeding the activity of docetaxel and paclitaxel (46% and 26%, respectively). Neurotoxicity was also substantially lower with tesetaxel compared with equi-myelotoxic doses of docetaxel. Among more than 350 patients (pts), there have been no occurrences of hypersensitivity reactions. An initial phase 2 study as 2nd-line therapy for pts with MBC who progressed after multidrug anthracycline-containing regimens showed a 38% partial response (PR) rate using tesetaxel Q3 wks at a dose of 27–35 mg/m2. We conducted a Phase 2, open-label, multicenter study of the efficacy and safety of tesetaxel as first-line therapy in women with MBC.

Methods: Eligible pts have Stage IV, HER2−negative MBC; ECOG PS 0–1; and adequate organ function. No prior chemotherapy is allowed (other than 1 regimen in the adjuvant setting). Tesetaxel was administered orally Q3 wks at a starting dose of 27 mg/m2 with escalation to 35 mg/m2 as tolerated. No premedication for potential hypersensitivity was used. RECIST response rate was the primary endpoint. A Simon min-max two-stage design was used with a target response rate of 30% in 25 pts.

Results: To date, 20 women have been enrolled and treated. The median age was 62 years (range, 45–78). Time from diagnosis was > 4 years in 5 pts and ≤ 4 years in 6; MBC was newly diagnosed in the remaining 9. Hormone receptor status was triple negative in 5 pts at diagnosis and 10 at the time of metastasis. The most common sites of metastasis were lung (13 pts) and bone (9). Prior treatment included hormonal therapy in 13 pts, adjuvant chemotherapy in 16 (most commonly, ACT), and radiotherapy in 9. Of 11 pts currently evaluable for response, PR was achieved in 6 (55%), with confirmation of response in 4 and an ongoing PR in 1 of the 2 pts with an unconfirmed PR. SD was observed in 2 and disease progression in 3. Neutropenia was the most common adverse event, affecting 50% of pts; Grade 3–4 occurrences were observed most often after escalation of the tesetaxel dose to 35 mg/m2. Single occurrences (Grade 1) of neuropathy and nail changes were reported. There were no occurrences of hypersensitivity.

Conclusions: Tesetaxel overcomes multiple disadvantages of standard parenteral taxanes and is highly active in 1st- and 2nd-line MBC. To date, overall response rates in these settings are 55% and 38%, respectively. In view of this, we have amended the trial to expand the initial cohort. Potential schedule-dependency will be examined in a future cohort with a newly developed weekly-times-3 schedule. Updated results in both cohorts will be presented.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-19-11.

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.

Cervical and colorectal cancer screening among breast cancer (BrCa) survivors followed in either a breast center (BC) or a breast survivorship clinic (SvC) at The University of Texas M.D. Anderson Cancer Center

e20506

Background: An essential component of cancer survivorship care includes the prevention and early detection of new cancers. We sought to determine if documentation of appropriate cervical and/or colon cancer screening differed between BrCa survivors followed in our BC (patients < 5 yrs from diagnosis of invasive BrCa or with active BrCa issues) and those seen in our SvC (patients with history of DCIS or ≥ 5 yrs from invasive BrCa diagnosis). Methods: IRB approval was obtained for this retrospective study. 5,982 BrCa survivors were seen for follow-up in our BC or SvC between 7/1/05 and 12/31/06. 2,811 BC patients and 1191 SvC patients (total = 4,002) met inclusion criteria: 1) not receiving chemotherapy, radiation, or undergoing surgical evaluation; 2) no evidence of recurrent BrCa; 3) ≥ 12 months from BrCa diagnosis, 4) no active GYN or GI complaints. Results: BrCa survivors followed our SvC were significantly more likely to have provider documentation of both cervical and colon cancer screening than those followed in our BC (72% versus 22.7%, and 68.4% versus 14.5%, respectively; both p values <0.001). Although nursing documentation of cervical cancer screening is required in both centers, SvC patients were more likely to have this documented than those in the BC (95.3% versus 56.5%, respectively; p <0.001). Nursing documentation of colon cancer screening is required in SvC (84.2% documented) but not in the BC (3.5% documented). Conclusions: BrCa survivors receiving care in our survivorship clinic were more likely to have nursing or provider documentation of cervical and/or colon cancer screening. Strategies that trigger documentation of non-BrCa screening take advantage of the “teachable moment” during a routine visit- thereby promoting the long-term health of cancer survivors.

No significant financial relationships to disclose.

Differential glucose uptake in retina- and brain-derived endothelial cells

Microangiopathy is a systemic complication of diabetes that is especially severe in the retinal microcirculation. The objective of this study was to compare glucose uptake and glucose transporter expression between retinal endothelial cells and the closely related endothelial cells derived from the cerebral microcirculation. Endothelial cells isolated from bovine brain, bovine retinal, and rat heart microvessels were cultured in the presence of control (5 mM) and high levels of (30 mM) d-glucose for 1-5 days. Glucose uptake by cultured endothelial cells was determined by measuring the uptake of [(3)H]deoxy-d-glucose and glucose transporter protein expression was assessed by Western blot. Our results showed that glucose uptake was significantly (P < 0.001) higher in brain- and heart-derived endothelial cells than in retinal endothelial cells at both physiologic and high concentrations of glucose. High levels of glucose caused a significant (P < 0.05) decrease in glucose uptake in brain-derived and heart endothelial cells but had no effect on retinal endothelial cells. Similarly, in response to high glucose levels there was a significant (P < 0.01) down regulation of GLUT-1 in brain-derived endothelial cells but not in retinal endothelial cells. These results suggest that despite a low basal level of glucose uptake the inability of retinal endothelial cells to down regulate glucose uptake in the presence of high glucose levels could make them especially sensitive to the deleterious effects of hyperglycemia in diabetes.

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.

Identifying physicians likely to benefit from depression education: a challenge for health care organizations

BACKGROUND

Few methods exist to identify physicians who might benefit from depression education.

OBJECTIVES

To develop a measure of physicians' confidence or self-efficacy in caring for depressed patients and assess it's reliability and validity.

RESEARCH DESIGN

A national sample of primary care physicians were surveyed and exploratory factor analysis (EFA) was used to identify factors underlying physicians' responses to 26 items. We named the factors, selected items with factor loadings > or = 0.50 for final scales, and tested a priori hypotheses about self-efficacy.

SUBJECTS

1) Random cross-sectional sample of family physicians, internists, obstetrician-gynecologists, and pediatricians (n = 5,369) and 2) 49 general internists and family physicians participating in a prepost evaluation of a depression workshop.

RESULTS

In the national sample, 3,712 physicians were eligible and 2,104 responded. Forty-six percent were female, and 51% were family physicians and general internists. EFA identified 5 factors, the first of which was called Self-Efficacy (4 items, alpha = 0.86). More family physicians (64%) had confidence (self-efficacy) in caring for depressed patients compared with general internists (33%), obstetrician-gynecologists (16%), and pediatricians (6%) (P < 0.001). Few physicians intended to change their care of depressed patients (10%) or take CME on depression (24%). Of the 49 physicians attending a depression workshop, 76% reported high self-efficacy after the workshop versus 50% before it (P = 0.013).

CONCLUSIONS

This study supports the reliability and validity of the Self-Efficacy scale as one method to identify physicians who might benefit from interventions. New approaches are needed because physicians are unlikely to change.

Insulin-mediated GLUT4 translocation is dependent on the microtubule network

The GLUT4 facilitative glucose transporter is recruited to the plasma membrane by insulin. This process depends primarily on the exocytosis of a specialized pool of vesicles containing GLUT4 in their membranes. The mechanism of GLUT4 vesicle exocytosis in response to insulin is not understood. To determine whether GLUT4 exocytosis is dependent on intact microtubule network, we measured insulin-mediated GLUT4 exocytosis in 3T3-L1 adipocytes in which the microtubule network was depolymerized by pretreatment with nocodazole. Insulin-mediated GLUT4 translocation was inhibited by more than 80% in nocodazole-treated cells. Phosphorylation of insulin receptor substrate 1 (IRS-1), activation of IRS-1 associated phosphatidylinositide 3-kinase, and phosphorylation of protein kinase B/Akt-1 were not inhibited by nocodazole treatment indicating that the microtubule network was not required for proximal insulin signaling. An intact microtubule network is specifically required for insulin-mediated GLUT4 translocation since nocodazole treatment did not affect insulin-mediated GLUT1 translocation or adipsin secretion. By using in vitro microtubule binding, we demonstrated that both GLUT4 vesicles and IRS-1 bind specifically to microtubules, implicating microtubules in both insulin signaling and GLUT4 translocation. Vesicle binding to microtubules was not mediated through direct binding of GLUT4 or insulin-responsive aminopeptidase to microtubules. A model microtubule-dependent translocation of GLUT4 is proposed.

Primary care pediatricians' roles and perceived responsibilities in the identification and management of depression in children and adolescents

OBJECTIVE

To describe primary care pediatricians' 1) approach to the identification and management of childhood and adolescent depression and 2) perception of their skills, responsibilities, and barriers in recognizing and managing depression in children and adolescents.

DESIGN AND METHODS

National cross-sectional survey of randomly selected primary care pediatricians that assessed the management of recalled last case of child or adolescent depression, attitudes, limitations to care from barriers and skills, and willingness to implement new educational or intervention strategies to improve care.

RESULTS

There were 280 completed surveys about child and adolescent depression (63% response rate). Pediatricians overwhelmingly reported it was their responsibility to recognize depression in both children and adolescents (90%) but were unlikely to feel responsible for treating children or adolescents (26%-27%). Those with most of their practice in capitated managed care were less likely to feel responsible for recognizing depression in either children or adolescents. Forty-six percent of pediatricians lacked confidence in their skills to recognize depression in children, and few of them (10%-14%) had confidence in their skills in different aspects of treatment with children or adolescents. Diagnostic, assessment, and management details for their last recalled case of depression in a child or adolescent were provided by 248 of these pediatricians. In addition to referring 78%-79% of the cases to mental health care professionals, 77% of pediatricians provided a wide range of brief interventions. Only 19%-20% prescribed medication. Major factors cited that limited their diagnosis or management were time (56%-68%) and training or knowledge of issues (38%-56%). Fewer pediatricians noted limitations due to insurer or financial issues (8%-39%) or patient issues (19%-31%). The 35% of pediatricians who were motivated to change their recognition and management of suspected depression were significantly more interested in implementing in the future a variety of new strategies to improve care.

CONCLUSION

Primary care pediatricians felt responsible for recognizing but not for treating child and adolescent depression. Although the lack of confidence and lack of knowledge and/or skills and time issues are major barriers that limit pediatricians in their treatment of childhood and adolescent depression, pediatricians varied in their readiness to change, with some being more willing to implement new strategies to care for depression. Educational and practice interventions need to focus on how to assist all pediatricians in diagnosis and to prepare these motivated pediatricians to manage depression in primary care settings.

Persistent increase in children's sun protection in a randomized controlled community trial

BACKGROUND

Reducing sun exposure during childhood may prevent skin cancer later in life. Sun protection increased immediately following implementation of the SunSafe multicomponent, community-based intervention delivered in 1996 through schools, day care centers, primary care offices, and beach recreation areas. Whether sun protection levels would remain higher than preintervention levels the following summer was unknown.

METHODS

A randomized controlled trial based in 10 New Hampshire towns addressed children's use of protective clothing, shade, and sunscreen at freshwater beach areas. The intervention was provided initially between March and May 1996. A brief project follow-up contact was provided to schools, day care centers, beaches, and primary care offices between March and May 1997 to restock intervention materials and to answer questions. Observations of 1490 children during June through August of 1997 were compared with observations made prior to any intervention between June and August of 1995.

RESULTS

In intervention towns, the proportion of children using at least some sun protection increased by 0.15 from 0.58 in 1995 to 0.73 in 1997 while the proportion in control towns increased by 0.03 (P = 0.033). This increase was due to more use of sunscreen, but not more use of protective clothing or shade. In 1997, care-givers of children in intervention towns reported receiving more sun protection information from school and health care sources than control town caregivers (62% versus 33%, P < 0.006).

CONCLUSIONS

In intervention communities, a higher proportion of children used sun protection in 1997 than at baseline. Increases from 1995 to 1997 were similar in magnitude to short-term increases between 1995 and 1996 that we have been previously reported.

Identification of a 30-base pair regulatory element and novel DNA binding protein that regulates the human GLUT4 promoter in transgenic mice

We have previously demonstrated that the important cis-acting elements regulating transcription of the human GLUT4 gene reside within 895 base pairs (bp) upstream of the transcription initiation site (Thai, M. V., Guruswamy, S., Cao, K. T., Pessin, J. E., and Olson, A. L. (1998) J. Biol. Chem. 273, 14285-14292). Our studies demonstrated that an MEF2 binding site within this region was necessary, but not sufficient, for GLUT4 promoter function in transgenic mice. We have identified a second regulatory element (Domain I) that functions cooperatively with the MEF2 domain in regulating GLUT4 transcription. Using a yeast-one hybrid screen, we obtained a partial cDNA and generated an antibody directed against a protein binding specifically to Domain I. Sequence analysis of the partial cDNA indicates that the protein binding to Domain I is a novel protein. The antibody specifically labels two proteins of approximately 70 and 50 kDa in Western blot analysis. These molecular masses correspond to Domain I binding proteins identified by UV-cross-linking nuclear extracts to a Domain I probe. The antibody raised against the Domain I binding protein inhibited formation of a Domain I-protein complex in electrophoretic mobility shift assays. We conclude that we have identified an authentic, novel, Domain I binding protein required for transcriptional regulation of the human GLUT4 promoter.

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.

Sun protection counseling for children: primary care practice patterns and effect of an intervention on clinicians

OBJECTIVES

To describe current primary care sun protection advice for children and assess the effect on clinicians of an intervention to enhance their sun protection advocacy.

SETTING

Primary care practices caring for children in New Hampshire with special attention to clinicians serving 10 towns that were involved in a randomized controlled trial of the multicomponent SunSafe intervention involving schools, recreation areas, and primary care practices.

DESIGN/INTERVENTION

A statewide survey of all primary care clinicians serving children addressed their self-reported sun protection advocacy practices. Clinicians in 10 systematically selected rural towns were involved in the subsequent intervention study. The primary care intervention provided assistance to practices in establishing an office system that promoted sun protection advice to children and their parents during office visits.

MAIN OUTCOME MEASURES

Sun protection promotion activities of primary care clinicians as determined by their self report, research assistant observation, and parent interviews.

RESULTS

Of 261 eligible clinicians responding to the statewide survey, about half provide sun protection counseling "most of the time" or "almost always" during summer well care visits. Pediatricians do so more often than family physicians. Clinicians involved in the intervention increased their use of handouts, waiting room educational materials, and sunscreen samples. Compared with control town parents, parents in intervention towns reported an increase in clinician sun protection advice.

CONCLUSIONS

The SunSafe primary care intervention increased sun protection counseling activities of participating clinicians. A single-focus preventive service office system is feasible to include in community interventions to promote sun protection.

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.

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.

A community-based randomized trial encouraging sun protection for children

OBJECTIVE

We evaluated the impact of an intervention promoting sun protection behavior among children 2 to 11 years of age through schools and day care centers, primary care practices, and recreation areas.

METHODS

Ten towns in New Hampshire were paired, then assigned randomly to intervention or control status. The multicomponent SunSafe intervention was provided to children and caregivers through primary care practices, day care centers, schools, and beach recreation areas. Training support and materials were provided by the SunSafe project, but project staff had no direct contact with children or parents in providing the intervention. All intervention components promoted the same message: avoid the sun between 11 AM and 3 PM, cover up using hats and protective clothing, use sun block with a sun protection factor >/=15, and encourage sun protection among family and friends. The impact of the intervention was determined by observing children's sun protection behavior at the beach during baseline compared with 1 year later. The primary outcomes of interest were changes in the proportion of children per town using at least some sun protection and changes in the proportion of children fully protected. Children were clustered by town, with the town thus being the unit of analysis. The primary care practice component included one practice meeting for clinicians and staff at which project staff presented background on skin cancer and how to promote its prevention; a sun protection office system manual based on our previous work, which provided specific direction on how to share responsibility among office staff and clinicians in carrying out routines that promote sun protection; and educational posters, pamphlets, and self-adhesive reminder notes designed to enhance sun protection counseling. SunSafe removable tattoos and stickers were offered to children at well-child and illness visits during the summer months. Schools each received three project staff visits: a brief visit with the principal to describe the intervention and to answer questions; an in-service program to educate teachers about skin cancer and to introduce curricular materials; and help with one parent outreach program. Larger day care centers each received one project staff visit. An additional six smaller day care centers received curricular materials through the mail but no visits. Two similar sets of curricular materials were used, one for grade schools and the other for preschools and day care centers. Both emphasized the importance of sun protection rather than the danger of skin cancer. Materials emphasized dynamic activities modeled after the "Slip, Slop, Slap" and "SunSmart" programs and included new material developed to suit regional needs. Both manuals offered structured plans but also provided a variety of activities from which teachers could choose. Teachers agreed to devote a minimum of two class periods to these materials. For recreation areas, lifeguards in each of the intervention communities attended an in-service meeting, during which background about skin cancer prevention was presented by project staff. The project also provided displays about the ultraviolet (UV) light index and about sun protection to be posted at each beach. Subsequently, project staff called beach staff in each community each morning with the predicted UV index for the day to post on the display. Educational pamphlets about the UV index and free sun-block samples were available to beachgoers through the lifeguards. One brief follow-up visit by project staff was made to each beach area to provide reinforcement.

RESULTS

We observed 1930 children. Use of some sunscreen on at least one body area increased in all 5 intervention towns compared with paired control towns. In intervention towns, this mean proportion increased from 0.56 of those observed at baseline to 0.76 of those observed postintervention, with a minimal increase among control town children. (ABSTRACT TRUNCATED

Myocyte enhancer factor 2 (MEF2)-binding site is required for GLUT4 gene expression in transgenic mice. Regulation of MEF2 DNA binding activity in insulin-deficient diabetes

We have previously demonstrated that important regulatory elements responsible for regulated expression of the human GLUT4 promoter are located between -1154 and -412 relative to transcription initiation (Olson, A. L., and Pessin, J. E. (1995) J. Biol. Chem. 270, 23491-23495). Through further analysis of this promoter regulatory region, we have identified a perfectly conserved myocyte enhancer factor 2 (MEF2)-binding domain (-CTAAAAATAG-) that is necessary, but not sufficient, to support tissue-specific expression of a chloramphenicol acetyltransferase reporter gene in transgenic mice. Biochemical analysis of this DNA element demonstrated the formation of a specific DNA-protein complex using nuclear extracts isolated from heart, hindquarter skeletal muscle, and adipose tissue but not from liver. DNA binding studies indicated that this element functionally interacted with the MEF2A and/or MEF2C MADS family of DNA binding transcription factors. MEF2 DNA binding activity was substantially reduced in nuclear extracts isolated from both heart and skeletal muscle of diabetic mice, which correlated with decreased transcription rate of the GLUT4 gene. MEF2 binding activity completely recovered to control levels following insulin treatment. Together these data demonstrated that MEF2 binding activity is necessary for regulation of the GLUT4 gene promoter in muscle and adipose tissue.

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.

Osmotic shock stimulates GLUT4 translocation in 3T3L1 adipocytes by a novel tyrosine kinase pathway

Similar to insulin, osmotic shock of 3T3L1 adipocytes stimulated an increase in glucose transport activity and translocation of GLUT4 protein from intracellularly localized vesicles to the plasma membrane. The docking/fusion of GLUT4 vesicles with the plasma membrane appeared to utilize a similar mechanism, since expression of a dominant interfering mutant of syntaxin-4 prevented both insulin- and osmotic shock-induced GLUT4 translocation. However, although the insulin stimulation of GLUT4 translocation and glucose transport activity was completely inhibited by wortmannin, activation by osmotic shock was wortmannin-insensitive. Furthermore, insulin stimulated the phosphorylation and activation of the Akt kinase, whereas osmotic shock was completely without effect. Surprisingly, treatment of cells with the tyrosine kinase inhibitor, genistein, or microinjection of phosphotyrosine antibody prevented both the insulin- and osmotic shock-stimulated translocation of GLUT4. In addition, osmotic shock induced the tyrosine phosphorylation of several discrete proteins including Cbl, p130(cas), and the recently identified soluble tyrosine kinase, calcium-dependent tyrosine kinase (CADTK). In contrast, insulin had no effect on CADTK but stimulated the tyrosine phosphorylation of Cbl and the tyrosine dephosphorylation of pp125(FAK) and p130(cas). These data demonstrate that the osmotic shock stimulation of GLUT4 translocation in adipocytes occurs through a novel tyrosine kinase pathway that is independent of both the phosphatidylinositol 3-kinase and the Akt kinase.

Solar protection of children at the beach

BACKGROUND

Excessive sun exposure during childhood has been associated with subsequent development of skin cancers. Children have been advised to avoid sun exposure, use protective clothing, and apply sunscreen lotions, but how completely these recommendations are followed has not been studied.

OBJECTIVE

To determine the extent of sun protection among children visiting lake beaches, the methods used, and the characteristics associated with more protection.

DESIGN

Direct observations of children were linked with concurrent care giver/parent interviews.

SUBJECTS/SETTING

A total of 871 children 2 to 9 years of age and their parents/care givers at freshwater beaches in 10 small New Hampshire towns during July and August 1995.

OUTCOME MEASURES

Protection of the head, torso, and legs according to method used (hats, shirts, pants, sunscreen, or shade).

RESULTS

Fifty-four percent of children were protected by at least one method for all three body surface regions, although 17% had no protection for any region. Sunscreen was used either alone or in combination with clothing for at least one region in 79%. Hats were used by 3%, shirts by 22%, and pants to the knee by 49%. Only 12% of observed children were in the shade. The region that was protected most often was the legs for boys (due to swim suit styles) followed by the torso for both sexes. The region most often unprotected was the legs for girls followed closely by the face for both boys and girls. Girls were significantly more likely to have no protection (31.2% female vs 7% male, chi2 83.3) due to better leg protection from swim trunks to the knees popular with boys. Full protection of all three regions was more common for children younger than 5 (odds ratio [OR] = 1.8, 95% confidence interval, [CI] 1.3-2.5), for children perceived to usually or always burn (OR = 2.0, 95% CI 1.4-2.7), for children whose parents had more than a high school education (OR = 1.8, 95% CI 1.3-2.5), and if the parents indicated receiving sun protection information from a school or clinician during the previous year (OR = 1.7, 95% CI 1.2-2.3). Approximately 51.6% of parents recalled receiving childhood solar protection advice in the past year from either their physician, a nurse, or a school/day care setting.

CONCLUSIONS

Sunscreen provided the most common form of solar protection. Hats and shade were used rarely, and shirts were also underused. Although the sun protection of these children visiting the beach was substantial, nearly half were still not fully protected. Clinician advice within the past year was associated with better protection. Clinicians could increase their influence by providing more specific counseling about how to achieve full protection. Use of multiple methods of protection rather than just sunscreen and full protection rather than protection for just one or two body regions should be emphasized. It is helpful to remind families to protect the regions most frequently omitted from protection: girls' legs and boys' and girls' faces. Advice can be enhanced with patient education materials such as included in the "Slip" (on a shirt), "Slop" (on sunscreen), and "Slap" (on a hat) program developed in Australia and available through the American Cancer Society.

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.

Structure, function, and regulation of the mammalian facilitative glucose transporter gene family

The facilitative transport of glucose across the plasma membranes of mammalian cells is catalyzed by a family of glucose transport proteins (GLUT). Four glucose transport proteins and a fructose transport protein have been identified. These transport proteins have unique tissue distributions and biochemical properties under- lying specific physiologic functions. GLUT1, the first GLUT isoform identified, is expressed at highest levels in the endothelial of barrier tissues such as blood vessels and the blood-brain barrier. GLUT2, found predominantly in liver, intestine, kidney, and pancreatic beta-cells, is a low-affinity glucose transport protein that is part of the glucose sensor in pancreatic beta-cells and facilitates either glucose uptake or efflux from the liver depending on the nutritional state. GLUT3 is the glucose transporter responsible for maintaining an adequate glucose supply to neurons. GLUT4 is the insulin-regulated glucose transporter found in adipose tissues, heart muscles, and skeletal muscles that is responsible for insulin-regulated glucose disposal.

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.

Preventive health care for children

This article discusses immunization, development, vision, blood pressure, dentition, behavioral, and environmental screening for preschool children. The authors then discuss screening for children in the early school years. Injury and violence prevention and topics of sexuality for the preadolescent are also presented.

Transcriptional regulation of the human GLUT4 gene promoter in diabetic transgenic mice

We previously reported that 2400 base pairs (bp) of 5'-flanking DNA is sufficient for tissue-specific and hormonal/metabolic regulation of the human GLUT4 gene in transgenic mice (Liu, M.-L., Olson, A. L., Moye-Rowley, W. S., Buse, J. B., Bell, G. I., and Pessin, J. E. (1992) J. Biol. Chem. 267, 11673-11676). To further define the DNA sequences required for GLUT4 expression, we generated transgenic mice carrying 1975, 1639, 1154, 730, and 412 bp of the GLUT4 5'-flank (hG4) fused to the chloramphenicol acetyltransferase (CAT) reporter gene. The 1975-hG4-CAT, 1639-hG4-CAT, and 1154-hG4-CAT constructs were expressed in a tissue-specific manner identical to the endogenous murine GLUT4 mRNA. Regulation of these reporter gene constructs in insulin-deficient diabetes also paralleled the endogenous gene. In contrast, 730-hG4-CAT was expressed at high levels only in skeletal muscle and at low levels in all of the other tissues examined. Additionally, expression of 412-hG4-CAT was completely unrestricted. Neither the 730-hG4-CAT nor the 412-hG4-CAT reporter genes displayed any insulin-dependent regulation. These data demonstrate that a skeletal muscle-specific DNA element is located within 730 bp of the GLUT4 5'-flanking DNA but that 1154 bp is necessary to direct the full extent of tissue-specific and insulin-dependent regulation of the human GLUT4 gene in transgenic mice.

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.

Myocyte enhancer factor 2 (MEF2) binding site is essential for C2C12 myotube-specific expression of the rat GLUT4/muscle-adipose facilitative glucose transporter gene

We have cloned and characterized the rat GLUT4 gene in order to identify the cis-DNA elements responsible for tissue-specific GLUT4 expression. In this study, a variety of luciferase reporter gene constructs were transiently transfected into C2C12 myoblasts and myotubes as a model for skeletal muscle differentiation. These data identified a 103-base pair fragment, located from -522 to -420 relative to the transcription initiation site, that was sufficient to account for GLUT4 C2C12 myotube-specific expression. This fragment was operationally defined as an enhancer since it conferred myotube-specific expression in the context of both the minimal native GLUT4 or the heterologous thymidine kinase promoters in an orientation-independent manner. Further, mutagenesis of this fragment demonstrated that a sequence analogous to the muscle creatine kinase myocyte enhancer factor 2 (MEF2) binding site (-466 and -457) was required for transcriptional activation. Electrophoretic mobility gel shift assays demonstrated specific binding activity to the GLUT4 MEF2 sequences which directly correlated with functional expression. Although this element was capable of directing myotube-specific expression when cloned as multiple copies into luciferase reporter gene constructs, the MEF2 sequence alone was insufficient to enhance GLUT4 expression. These data demonstrated that GLUT4 muscle-specific expression is conferred by a 103-base pair DNA sequence located between -522 and -420 of rat GLUT4 gene. This region encompasses a MEF2 binding site which was necessary, but not sufficient, for transcriptional activation.

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.

In vivo association of Grb2 with pp116, a substrate of the T cell antigen receptor-activated protein tyrosine kinase

Numerous recent studies have implicated the src homology 2 and 3 domain-containing protein, Grb2, in coupling protein tyrosine kinase signaling pathways with the Ras signaling pathway. Ligation of the T cell antigen receptor results in the activation of both a PTK, and Ras; therefore, we investigated whether Grb2 may serve a similar function in T cells. Here we report that a GST/Grb2 fusion protein associates with several tyrosine phosphoproteins from lysates of T cell antigen receptor-stimulated Jurkat T cells. Two of these proteins, pp36 and pp116, bind to the Grb2 fusion protein with high affinity. Through the use of mutated Grb2 fusion proteins, we demonstrate that pp116 binds the amino-terminal src homology 3 domain of Grb2, the same domain of Grb2 thought to be primarily responsible for its interaction with SOS. We demonstrate further that pp116 associates with Grb2 in vivo, and we provide evidence that in the Jurkat T cell line Grb2 may exist complexed with either pp116 or with SOS.

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.

Cognitive coping strategies of children with chronic illness

Children with chronic illness need to adapt to more stresses than do healthy children. Research highlights the problems of children with chronic illnesses but not how they cope in response to the stress created by these problems. Cognitive appraisal of a stressor and of response options is an important aspect of coping. Our cross-sectional study investigated whether children with chronic illness used cognitive strategies for coping as often as did healthy children. One hundred seventy five children from summer camps with juvenile arthritis, asthma, or diabetes were compared with 145 healthy school children. Spontaneous responses to common painful and stressful events were categorized into coping or catastrophizing ideation. Data on anxiety, disease severity, and other sociodemographic variables were obtained. Coping strategies were reported by 64% of children with chronic illness and 63% of healthy children and varied significantly with age (p < .05) in both groups. Children with different chronic illnesses performed similarly except for a trend among children with severe juvenile rheumatoid arthritis who had higher rates of coping. For the individual stressful events, the rate of coping varied from 46% to 86%. The highest rates of coping responses were found with the child's recent personal stressful event where adolescents with chronic illness were twice as likely to offer more complex coping responses. More children with chronic illness than healthy children offered coping strategies in response to venipuncture (p < .001) but not to dental injection. Children with chronic illness report coping as their predominant strategy for adapting to common painful and stressful events.(ABSTRACT TRUNCATED AT 250 WORDS)

Overall function in rural childhood cancer survivors. The role of social competence and emotional health

This study compared the functioning of 20 rural cancer survivors, aged 6 to 16 years, with that of 40 age- and gender-matched school peers. Social competence and emotional health were evaluated, along with academic performance and physical limitations. Eight measures were used: the teacher and parent Child Behavior Check Lists, the Health Resources Inventory, the Vineland Revised Scale of Social Maturity, the Piers-Harris Child's Self-Concept Scale, the Parcel and Meyers' Health Locus of Control, the Moos' Family Environment Scale, and the Functional Status II(r). Cancer survivors and controls had similar attitudes about self-esteem, family conflicts, physical functioning, social skills, independence, and sense of control over health. Both parents and teachers noted poorer social competence among the cancer survivors than among controls, but parents of survivors reported more behavior problems, whereas teachers stressed poorer school performance. Routine screening for emotional health, social competence, and academic performance should be part of the follow-up care of pediatric cancer survivors.

Hormonal/metabolic regulation of the human GLUT4/muscle-fat facilitative glucose transporter gene in transgenic mice

To examine the hormonal/metabolic as well as tissue-specific expression of the GLUT4/muscle-fat facilitative glucose transporter gene, we have generated several transgenic mouse lines expressing a human GLUT4 mini-gene which extends 5.3 kilobases (kb) upstream of transcription start and terminates within exon 10. This construct (hGLUT4-11.5) was expressed in a tissue-specific pattern identical to the endogenous mouse GLUT4 gene. The transcription initiation sites of the transgenic construct were similar to the GLUT4 gene expressed in human tissues. To investigate the hormonal/metabolic-dependent regulation of GLUT4, the transgenic animals were made insulin-deficient by streptozotocin (STZ) treatment. In these animals, STZ-induced diabetes resulted in a parallel decrease in endogenous mouse GLUT4 mRNA and the transgenic human GLUT4 mRNA in white adipose tissue, brown adipose tissue, and cardiac muscle. Similarly, insulin treatment of the STZ-diabetic animals restored both the endogenous mouse and transgenic human GLUT4 mRNA levels. To further define cis-regulatory regions responsible for this hormonal/metabolic regulation, the same analysis was performed on transgenic animals which carry 2.4 kb of the human GLUT4 5'-flanking region fused to a CAT reporter gene (hGLUT4[2.4]-CAT). This reporter construct responded similarly to the human GLUT4 mini-gene demonstrating that the element(s) controlling hormonal/metabolic regulation and tissue specificity all reside exclusively within 2.4 kb of the transcriptional initiation site.

Regulation of the GLUT4/muscle-fat glucose transporter mRNA in adipose tissue of insulin-deficient diabetic rats

Previous studies have documented that streptozotocin-induced insulin deficiency results in a marked decrease in adipose tissue GLUT4 glucose transporter mRNA levels (Sivitz, W.I., DeSautel, S.L., Kayano, T., Bell, G.I., and Pessin, J.E. (1989) Nature 340, 72-74). In this study, nuclear run-on analysis performed on diabetic and insulin-treated diabetic rats demonstrated that the decrease in GLUT4 mRNA occurs via a diabetes-induced decrease in GLUT4 transcription rate. The decrease in GLUT4 mRNA levels could be prevented by treatment of the diabetic animals with the adenosine receptor agonist phenylisopropyl-adenosine (PIA). Under these conditions, PIA completely blocked the elevation of intracellular cAMP levels associated with insulin deficiency. Surprisingly, isolation of primary rat adipocytes from control animals resulted in a rapid decrease (approximately 20-fold) in GLUT4 mRNA levels by 24 h with a concomitant increase (approximately 70-fold) in GLUT1 mRNA levels. This rapid loss of GLUT4 expression did not correlate with changes in adipocyte cAMP levels and was not prevented by treatment of the cells with either insulin and/or PIA. These data demonstrate that the decrease in GLUT4 transcription induced by insulin deficiency in vivo predominantly results from an increase in intracellular cAMP levels. In contrast, although GLUT4 transcription also decreases in adipocytes when removed from their normal physiological environment, this occurs independent of changes in cAMP levels.

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.

Intracellular processing of the N-terminal ORF 1a proteins of the coronavirus MHV-A59 requires multiple proteolytic events

Several polypeptide products of MHV-A59 ORF 1a were characterized in MHV-A59 infected DBT cells, using antisera directed against fusion proteins encoded in the first 6.5 kb of ORF1a. These included the previously identified N-terminal ORF 1a product, p28, as well as 290-, 240-, and 50-kDa polypeptides. P28 was always detected as a discrete band without larger precursors, suggesting rapid cleavage of p28 immediately after its synthesis. Once p28 was cleaved there was little degradation of the protein over a 2-hr period. The intracellular cleavage of p28 was not inhibited by the protease inhibitor leupeptin, in contrast to results obtained during in vitro translation of genome RNA (Denison and Perlman, 1986). These data suggest that different protease activities may be responsible for the cleavage of p28 in vitro and in vivo. The 290-kDa protein was an intermediate cleavage product derived from a precursor of greater than 400 kDa. The 290-kDa product was subsequently cleaved into secondary products of 50 and 240 kDa. The intracellular cleavage of the 290-kDa polypeptide was inhibited by leupeptin at concentrations which did not inhibit the early cleavage of p28 or the cleavage of the 290-kDa product from its larger polyprotein precursor. In the presence of zinc chloride, a product of greater than 320 kDa was detected, which appears to incorporate p28 at its amino terminus. This suggests that at least two protease activities may be necessary for processing of ORF1a proteins, one of which cleaves p28 and is sensitive to zinc chloride but resistant to leupeptin, and the other which cleaves the 290-kDa precursor and is sensitive to both inhibitors. Both the 290- and 240-kDa proteins should contain sequences predicted to encode two papain-like protease activities.

Expression and regulation of the human GLUT4/muscle-fat facilitative glucose transporter gene in transgenic mice

To study the molecular basis of tissue-specific expression of the GLUT4/muscle-fat facilitative glucose transporter gene, we generated lines of transgenic mice carrying 2.4 kilobases of the 5'-flanking region of the human GLUT4 gene fused to a chloramphenicol acetyltransferase (CAT) reporter gene (hGLUT4[2.4]-CAT). This reporter gene construct was specifically expressed in tissues that normally express GLUT4 mRNA, which include both brown and white adipose tissues as well as cardiac, skeletal, and smooth muscle. In contrast, CAT reporter activity was not detected in brain or liver, two tissues that do not express the GLUT4 gene. In addition, the relative levels of CAT mRNA driven by the human GLUT4 promoter in various tissues of these transgenic animals mirrored those of the endogenous mouse GLUT4 mRNA. Since previous studies have observed alterations in GLUT4 mRNA levels induced by fasting and refeeding (Sivitz, W. I., DeSautel, S. L., Kayano, T., Bell, G. I., and Pessin, J. E. (1989) Nature 340, 72-74), the regulated expression the hGLUT4[2.4]-CAT transgene was also assessed in these animals. Fasting was observed to decrease CAT activity in white adipose tissue which was super-induced upon refeeding. These alterations in CAT expression occurred in parallel to the changes in endogenous mouse GLUT4 mRNA levels. Although CAT expression in skeletal muscle and brown adipose tissue was unaffected, the endogenous mouse GLUT4 mRNA was also refractory to the effects of fasting/refeeding in these tissues. These data demonstrate that 2.4 kilobases of the 5'-flanking region of the human GLUT4 gene contain all the necessary sequence elements to confer tissue-specific expression and at least some of the sequence elements controlling the hormonal/metabolic regulation of this gene.

Negative regulation of angiotensinogen gene expression by glucocorticoids in fetal sheep liver

The effect of glucocorticoids in regulating liver angiotensinogen gene expression was studied in chronically instrumented fetal sheep during the last trimester of gestation and was compared with the expression of other hepatic genes (prothrombin, factor IX, and albumin). Four sets of twins were studied at 118 d of gestation, and three sets were studied at 138 d of gestation (term, 145 d). One of each set of twins was infused intraperitoneally with cortisol (5 mumol.mL-1.h-1) for 48 h, whereas the other twin received the same volume (1 mL/h) of normal saline. Plasma cortisol concentration increased from 0.32 +/- 0.12 and 2.7 +/- 0.12 nmol/100 mL to 44.2 +/- 20.0 and 37.7 +/- 8.2 nmol/100 mL in 118- and 138-d fetuses, respectively, during the cortisol infusion; no changes were observed in fetuses infused with saline alone. At the end of the infusion period, the animals were anesthetized, the fetal liver was removed, and total cellular RNA was isolated and probed for angiotensinogen, prothrombin, factor IX, and albumin. The results demonstrated that cortisol infusion decreased angiotensinogen mRNA by 61% in 138-d fetuses and albumin mRNA expression by 2.4-fold in 118-d fetuses and by 3.4-fold in 138-d fetuses. On the other hand, cortisol had no effect on fetal factor IX gene expression but increased prothrombin mRNA levels by 65% in 118-d fetuses and 62% in 138-d fetuses. Taken together, our results suggest that, during fetal life, angiotensinogen gene expression is negatively regulated by glucocorticoids. This effect is not universal because cortisol increases fetal prothrombin gene expression.

Identification of the spinal cord as a major site of persistence during chronic infection with a murine coronavirus

After intranasal inoculation, mouse hepatitis virus (MHV) gains entry into the central nervous system (CNS) via the olfactory and trigeminal nerves. Under the appropriate conditions, some mice develop clinically apparent demyelinating encephalomyelitis several weeks later, with virus always present in the spinal cord. To determine the pathway by which virus reaches the cord, brains and spinal cords of infected, asymptomatic mice were analyzed by in situ hybridization. Viral RNA was always detected in the anterior part of the upper spinal cord. A similar analysis of mice with the recent onset of hindlimb weakness showed that viral RNA was detected in the same location. The results suggest that MHV is transported to the spinal cord via well-defined neuroanatomic pathways and that viral amplification with resultant clinical disease occurs from this site of persistence in the anterior spinal cord. This process of viral amplification may involve the generation of viral variants as has been described for MHV-infected rats. No major changes in viral RNA or protein could be detected when MHV isolated from mice with hindlimb paralysis was analyzed. The data suggest that the generation of viral variants is not important in the pathogenesis of the late onset of neurological disease induced by MHV in mice.

Developmental regulation of angiotensinogen gene expression in sheep

It has been suggested that the liver is not the main source of angiotensinogen during fetal life in rats, but that the kidney is an important site of fetal angiotensinogen synthesis. In an effort to determine if this phenomenon is specific to the rat or applicable to other species, we compared the ontogenic changes in hepatic and renal angiotensinogen mRNA expression in fetal (60, 90, 118, and 138 d of gestation, term being 145 d), newborn (7 d postnatal), and adult sheep. Total RNA was extracted, subjected to Northern blotting and hybridized using a full-length rat radiolabeled antisense RNA. Angiotensinogen mRNA sequences were detected in all fetal liver samples and appeared to increase 3-fold from 60 to 138 d gestation and then to decrease after birth. In contrast, angiotensinogen mRNA could not be detected in renal cortical tissue of 118 or 138 d fetuses, or newborn or adult sheep. We conclude that, unlike in the rat, liver angiotensinogen gene expression is detectable during the 2nd trimester of gestation in sheep and is developmentally regulated. Furthermore, in contrast to the fetal rat, angiotensinogen mRNA sequences were undetectable in fetal sheep kidney.

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.

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.

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.

gamma-Butyrobetaine hydroxylase activity is not rate limiting for carnitine biosynthesis in the human infant

Carnitine biosynthesis was assessed in human infants by measuring changes in plasma carnitine concentration and rates of urinary carnitine excretion after infants were fed carnitine-free formulas with and without added epsilon-N-trimethyl-L-lysine or gamma-butyrobetaine. This study was undertaken to test the hypothesis that carnitine biosynthesis in the human infant is regulated by substrate availability rather than activity of gamma-butyrobetaine hydroxylase, the final enzyme in the carnitine biosynthetic pathway. Ten infants were fed carnitine-free formula supplemented with either 500 microM epsilon-N-trimethyl-L-lysine or 500 microM gamma-butyrobetaine for 14 d. Plasma carnitine concentration and rate of urinary carnitine excretion were measured in infants before and after this period. Plasma carnitine concentration increased twofold when infants were fed either epsilon-N-trimethyl-L-lysine and increased threefold when infants were fed gamma-butyrobetaine. The rate of carnitine excretion doubled when infants were fed epsilon-N-trimethyl-L-lysine and increased 30-fold when infants were fed gamma-butyrobetaine. Absorption of epsilon-N-trimethyl-L-lysine was verified by demonstrating increased urinary excretion of epsilon-N-trimethyl-L-lysine in infants fed this substrate. We conclude that gamma-butyrobetaine hydroxylase activity is not rate limiting for carnitine biosynthesis in the human infant. Development of renal and hepatic gamma-butyrobetaine hydroxylase activity was determined in necropsy tissue from individuals of various ages. It was verified that gamma-butyrobetaine hydroxylase activity is developmentally regulated in the liver, but not in the kidney. The clinical relevance of this observation is diminished in view of the results of the in vivo studies of carnitine biosynthesis in infants.