Neurotrophic regulation of insulin-sensitive amino acid uptake in rat fast muscle

Our object was to determine how innervation regulates muscle insulin sensitivity. Insulin-stimulated uptake of the nonmetabolized amino acid, 2-amino-isobutyric acid, was used as a measure of insulin sensitivity in denervated rat extensor digitorum longus muscles retaining either a similar 2.5-cm ("proximal denervation') or a similar to 0.5-cm ("distal denervation') length of distal nerve stump. Because both muscles were inactive in the first 24 h, any difference in insulin sensitivity could be due only to some trophic influence of the distal nerve stump. Fifteen hours after either type of denervation, 2-aminoisobutyric acid uptake was refractory to insulin. However, at 24 h, insulin sensitivity of distally denervated muscles (with or without a second ipsilateral proximal denervation) was normal, whereas that of proximally denervated muscles was still relatively insensitive. In the absence of insulin, the two types of denervated muscles at 24 h showed no difference in 2-aminoisobutyric acid uptake. Finally, organ culture of paired muscles with or without long nerve stumps showed corresponding differences in insulin-stimulated 2-aminoisobutyric acid uptake after 48 h in vitro. Thus, a neurotrophic factor, independent of impulse activity, stretch, or changes in blood flow, regulates one type of muscle insulin sensitivity.     

Microbiological profiles of the Viking spacecraft

Planetary quarantine requirements associated with the launch of two Viking spacecraft necessitated microbiological assessment during assembly and testing at Cape Canaveral and the Kennedy Space Center. Samples were collected from selected surface of the Viking Lander Capsules (VLC), Orbiters, (VO), and Shrouds at predetermined intervals during assembly and testing. Approximately 7,000 samples were assayed. Levels of bacterial spores per square meter on the VLC-1 and VLC-2 were 1.6 x 10(2) and 9.7 x 10(1), respectively, prior to dry-heat sterilization. The ranges of aerobic mesophilic microorganisms detected on the VO-1 and VO-2 at various sampling events were 4.2 x 10(2) to 4.3 x 10(3) and 2.3 x 10(2) to 8.9 x 10(3)/m2, respectively. Approximately 1,300 colonies were picked from culture plates, identified, lypholipized, and stored for future reference. About 75% of all isolates were microorganisms considered indigenous to humans; the remaining isolates were associated with soil and dust in the environment. The percentage of microorganisms of human origin was consistent with results obtained with previous automated spacecraft but slightly lower than those observed for manned (Apollo) spacecraft.     

Clinical diagnosis with the stable isotope 13C in CO2 breath tests: methodology and fundamental considerations

The methodology for measuring in vivo oxidation of substrates labeled with the nonradioactive carbon isotope 13C has been developed with isotope ratio mass spectrometry. The use of 13C offers the possibility of utilizing CO2 breath tests in infants, children, pregnant women, and all subjects in whom 14CO2 breath tests cannot be used. The excretion of 140 nmol/kg-hr of 13CO2 produced from the oxidation of the labeled substrate could be detected with 95% confidence during a total CO2 excretion of 9 mM/kg-hr. The precision of CO2 breath tests using 13C is limited by the natural fluctuations of the ratio of 13C/12C in expired CO2, which occur with a standard deviation of 0.72%, or approximately 7 parts 13CO2 per 10(6) parts expired CO2. Larger excursions in the ratio were observed if the subjects ate shortly before or during the breath test. Clinically significant diagnostic tests can reasonably be expected to require the excretion of 2 to 20 times as much labeled CO2, or 0.28 to 1.4 micronM/kg-hr.     

A transgenic myogenic cell line lacking ryanodine receptor protein for homologous expression studies: reconstitution of Ry1R protein and function

CCS embryonic stem (ES) cells possessing two mutant alleles (ry1r-/ry1r-) for the skeletal muscle ryanodine receptor (RyR) have been produced and injected subcutaneously into severely compromised immunodeficient mice to produce teratocarcinomas in which Ry1R expression is absent. Several primary fibroblast cell lines were isolated and subcloned from one of these tumors that contain the knockout mutation in both alleles and exhibit a doubling time of 18-24 h, are not contact growth inhibited, do not exhibit drastic morphological change upon serum reduction, and possess the normal complement of chromosomes. Four of these fibroblast clones were infected with a retrovirus containing the cDNA encoding myoD and a puromycin selection marker. Several (1-2 microg/ml) puromycin-resistant subclones from each initial cell line were expanded and examined for their ability to express myoD and to form multinucleated myotubes that express desmin and myosin upon removal of mitogens. One of these clones (1B5 cells) was selected on this basis for further study. These cells, upon withdrawal of mitogens for 5-7 d, were shown by Western blot analysis to express key triadic proteins, including skeletal triadin, calsequestrin, FK506-binding protein, 12 kD, sarco(endo)plasmic reticulum calcium-ATPase1, and dihydropyridine receptors. Neither RyR isoform protein, Ry1R (skeletal), Ry2R (cardiac), nor Ry3R (brain), were detected in differentiated 1B5 cells. Measurements of intracellular Ca2+ by ratio fluorescence imaging of fura-2-loaded cells revealed that differentiated 1B5 cells exhibited no responses to K+ (40 mM) depolarization, ryanodine (50-500 microM), or caffeine (20-100 mM). Transient transfection of the 1B5 cells with the full-length rabbit Ry1R cDNA restored the expected responses to K+ depolarization, caffeine, and ryanodine. Depolarization-induced Ca2+ release was independent of extracellular Ca2+, consistent with skeletal-type excitation-contraction coupling. Wild-type Ry1R expressed in 1B5 cells were reconstituted into bilayer lipid membranes and found to be indistinguishable from channels reconstituted from rabbit sarcoplasmic reticulum with respect to unitary conductance, open dwell times, and responses to ryanodine and ruthenium red. The 1B5 cell line provides a powerful and easily managed homologous expression system in which to study how Ry1R structure relates to function.     

Peripheral nerve blocks improve analgesia after total knee replacement surgery

Using an in vitro cell system and Cs+ NMR techniques we were able to show that porcine aortic endothelial cells (PAEC) reduce their Na(+)-K(+)-ATPase activity upon an increase in intracellular cAMP. Reduction in the pump rate was due to phosphorylation of the alpha-subunit of the ATPase as shown by immunoprecipitation. Apart from a pump inhibiton using 8-Br-cAMP and IBMX, we were also able to show that changes in the Na(+)-K(+)-ATPase activity could be mediated by the adenosine-A2 and prostaglandin receptor agonists 5'-N-Ethylcarboxamidoadenosine and Iloprost, respectively. Parallel to a decrease in pump activity we also observed a decrease in intracellular Cs+, indicating opening of K+ channels.     

Optimization of evening insulin dose in patients using the short-acting insulin analog lispro

OBJECTIVE: A three-way, crossover, open-label, randomized study was designed to compare the evening and night (1800-0800) glycemic control when the evening premeal lispro dose was reduced by 20% and the bedtime basal NPH dose increased by 25%, or when the basal NPH dose was moved to before dinner at 1800, compared with the control arm on standard premeal human regular insulin and pre-bedtime NPH insulin. RESEARCH DESIGN AND METHODS: A total of 13 type 1 diabetic patients who use a premeal plus basal insulin regimen were studied on three separate days, with identical meals and snacks at the same times on each study day. On the control study day, patients received human regular insulin before dinner and NPH at bedtime in their usual doses. On another day, lispro was given before dinner with a dose reduction of 20%, and NPH at bedtime at 125% of usual dose. In the third regimen, the lispro and NPH were administered together in their usual dose before the evening meal by separate injections. The three regimens were tested in random order. RESULTS: Postprandial (1800-2200) blood glucose concentrations were lower after reduced-dose lispro compared with human regular insulin (6.0 +/- 0.3 [SEM] vs. 7.4 +/- 0.3 mmol/l, P < 0.05). Nighttime (2400-0400) blood glucose concentrations were not different (8.6 +/- 0.3 vs. 9.2 +/- 0.3 mmol/l, NS), and prebreakfast concentrations were also unchanged (7.7 +/- 0.9 vs. 8.7 +/- 0.8 mmol/l) after lispro with increased-dose NPH compared with standard insulin. By contrast, both nighttime (10.0 +/- 0.3 mmol/l, P < 0.05) and fasting glucose concentrations (10.8 +/- 0.6 mmol/l, P < 0.05) were significantly higher with dinnertime usual-dose lispro plus dinnertime usual-dose NPH compared with standard human insulin. Hypoglycemia at night (blood glucose < 3.0 mmol/l) did not differ between study days, but it was more frequent postprandially after dinner usual-dose lispro plus early NPH (2 vs. 7 patients, P = 0.062). CONCLUSIONS: With lower mealtime and higher basal bedtime insulin doses, patients using insulin lispro may be able to gain an overall improvement in evening blood glucose control without deteriorated nighttime glucose levels. Earlier basal NPH dosage alone does not ameliorate the nighttime hyperglycemia of short-acting insulin analog regimens.     

Psychologist as teacher and mentor: Affirming ethical values throughout the curriculum.

Argues that those involved in mentoring and teaching graduate students in professional psychology training programs must be concerned with 2 extracurricular issues when they consider how to influence students' ethical behavior. First, they must be ethical in their own interactions with students. Second, they must deal responsibly with students when students engage in unethical or unprofessional conduct. It is argued that the implicit attitudes and explicit behavior of faculty communicate as much as course content about being ethical. Last, strategies are identified for handling these special responsibilities on the basis of the Ethical Principles of Psychologists (American Psychological Association, 1990) and the broader ethical principles underlying those standards. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prospects for adoptive T cell therapy

Recent advances in neutron and X-ray sources and instrumentation, new and improved scattering techniques, and molecular biology techniques, which have permitted facile preparation of samples, have each led to new opportunities in using small-angle scattering to study the conformations and interactions of biological macromolecules in solution as a function of their properties. For example, new instrumentation on synchrotron sources has facilitated time-resolved studies that yield insights into protein folding. More powerful neutron sources, combined with molecular biology tools that isotopically label samples, have facilitated studies of biomolecular interactions, including those involving active enzymes.     

Synthesis, structure, dopamine transporter affinity, and dopamine uptake inhibition of 6-alkyl-3-benzyl-2-[(methoxycarbonyl)methyl]tropane derivatives

A series of 6-alkyl-3 beta-benzyl-2-[(methoxycarbonyl)methyl]tropane analogues were synthesized and evaluated as cocaine binding site ligands at the dopamine transporter (DAT). The in vitro affinity (Ki) for the DAT of the 6-alkyl-3 beta-benzyl-2-[(methoxycarbonyl) methyl]tropane analogues was determined by inhibition of [3H]WIN 35,428 in rat caudate putamen tissue. The inhibition of dopamine uptake (IC50) was also measured for selected compounds which demonstrated moderate affinity for the dopamine transporter. The unsubstituted enantiopure analogues (-)-19a (Ki = 33 nM) and surprisingly (+)-20a (Ki = 60 nM) were found to be almost equipotent with the high-affinity binding components of cocaine and WIN 35,065-2 and exhibited slightly more potent dopamine uptake inhibition than both cocaine and WIN 35,065-2. In general, substitution at the 6-position of racemic 19a and 20a with alkyl groups was found to result in decreased activity relative to increased chain length of the substituent. The 3 beta-benzyl-2 beta-[(methoxycarbonyl)methyl]-6 beta-methyltropane (21b; Ki = 57 nM) was the only 6-alkyl derivative to exhibit moderately potent activity. The 6 beta-isomer 21b was 4-fold more potent than the 6 alpha-isomer 19b (Ki = 211 nM) and was nearly equipotent with (-)-19a and (+)-20a as well as with cocaine and WIN 35,065-2. The results of this study further demonstrate the steric constraints associated with the C(6)-C(7) methylene bridge of the tropane ring system for molecular recognition of cocaine analogues at the cocaine binding site(s) on the DAT.     

Selective disruption of lymphotoxin ligands reveals a novel set of mucosal lymph nodes and unique effects on lymph node cellular organization

Lymphotoxin (LT) provides a critical signal for the genesis of lymph nodes (LN) in mice. Here we show that mice treated in utero with LT beta-R-Ig, which binds to the membrane LT alpha 1 beta 2 heterotrimer, lacked most LN, yet retained a set of mucosal surface draining LN. Since mice genetically deficient in LT alpha lack all LN, including the mucosal set, we hypothesize that a novel LT alpha-dependent pathway controls their genesis. This novel set of mucosal LN cannot be discriminated on the basis of addressin expression. The discovery of LN in mice treated with LT beta-R-Ig fusion protein in utero allowed us to compare the roles of membrane LT alpha beta or soluble LT alpha/tumor necrosis factor (TNF) in the development of cellular organization in LN and spleen. Our results indicate that both membrane LT alpha beta and soluble LT alpha/TNF mediate T-B cell segregation and the organization of B cell follicles in spleen and LN. Interestingly, while antagonism of membrane LT alpha beta or soluble LT alpha/TNF prevented germinal center (GC) formation in spleen, antagonism of soluble LT alpha/TNF had no effect on LN formation. The data suggest that multiple LT/TNF ligands control B cell follicle organization in the spleen and LN of adult mice, and that the requirements for LT/TNF ligands in GC formation are distinct in the different lymphoid organs.