Protein modification by thermal processing

This paper is a review concerning the way in which heat treatment can modify the allergenicity of food proteins. Any food protein may be allergenic if it can be absorbed intact, or as substantial fragments, through the gut mucosa and then evoke an immune (allergic) response. The intrinsic properties of the protein, the overall composition of the food, and the past processing history (especially thermal processing) all have an effect on the allergic potential. When a protein is denatured by heat, most of the original tertiary structure is lost, so that many of the sites recognized by antibodies on the native molecule are destroyed. There are many examples of allergenicity being reduced, but not eliminated, by heating. But heat-denatured proteins can also present new antigenic sites, uncovered by the unfolding process or created by new chemical reactions with other molecules present in the food (e.g., beta-lactoglobulin associating with alpha-lactalbumin in milk). We have found that heat-denatured beta-lactoglobulin has at least one new epitope, not found in the native state. Therefore, thermal processing can be part of a procedure for making hypoallergenic food, but will rarely be sufficient on its own. Increased understanding will help in evaluating novel proteins and processes.

Drug targeting using low density lipoprotein (LDL): physicochemical factors affecting drug loading into LDL particles

Low density lipoprotein (LDL) has been found suitable as a targeting carrier for cytotoxic drugs. However, higher drug loading into LDL particles without disrupting their native integrity remains a major obstacle. The purpose of this study is to investigate the different physicochemical factors that may affect drug loading and to characterize LDL-drug conjugates. Doxorubicin (Dox) and 3', 5'-O-dipalmitoyl-5-iodo-2'-deoxyuridine (dpIUdR) were used as reference cytotoxic drugs. Drugs were loaded into LDL particles using the dry film method with or without surfactants, liposomal and the direct addition method. The effects of incubation temperature, time and stoichiometry of LDL-drug conjugates on drug loading were investigated. The LDL-drug conjugates were evaluated for their stability and characterized by differential scanning calorimetry (DSC), denatured gel (SDS-PAGE), and electron microscopy (EM). We have suitably incorporated 45+/-10 Dox and 150+/-25 dpIUdR molecules/LDL particle. A seven-fold increase in Dox incorporation was achieved with the liposomal preparation compared to the dry film method. A 4- to 6-h incubation at 37 degreesC was suitable to restore the native structure of LDL particles. No apo B fragmentation of LDL particles was noted on denatured gel. DSC studies showed no change in the Tm of the LDL and the LDL-drug conjugates. An increase in particle size of LDL-dpIUdR, not LDL-Dox was observed in EM compared to the native LDL which may be related to higher incorporation of dpIUdR. The results indicate that physicochemical factors significantly affect drug loading efficiency and may need to be considered to optimize drug incorporation into LDL particles.

Pharmacokinetics of pentoxifylline and its metabolites in healthy mice and in mice infected with Candida albicans

Pentoxifylline has immunomodulatory properties and has been shown to decrease organ damage and improve survival in animals with gram-negative sepsis or endotoxemia. This effect is mediated by a reduction in endotoxin-induced production of tumor necrosis factor alpha (TNF-alpha) by the host. In earlier studies, we observed an unexpected increase in mortality in mice infected with Candida albicans that were given pentoxifylline even though concentrations of TNF-alpha in serum were not affected. The current study was designed to determine whether the pharmacokinetics of pentoxifylline and its metabolites were altered in C. albicans-infected mice and, if so, whether these changes could have contributed to the increased mortality. Noninfected mice and mice infected with C. albicans were treated with pentoxifylline (60 mg/kg of body weight) intraperitoneally every 8 h. Serum was collected from animals after one (day 0), four (day 1), or seven (day 2) injections of pentoxifylline or saline (controls). The first dose was administered 6 h after C. albicans infection. Serum was pooled. Concentrations of pentoxifylline and metabolites I, IV, and V were determined by capillary gas chromatography. Renal function and hepatic profiles were assessed. Pharmacokinetic parameters (maximum concentration of pentoxifylline in serum, half-life, and area under the concentration-time curve from 0 h to infinity [AUC(0)-infinity]) for all noninfected mice were similar and did not differ from those for day 0-infected mice. For day 1-infected mice, values of these three pharmacokinetic parameters for pentoxifylline and metabolite I were increased two- to fourfold over values for noninfected and day 0-infected mice. For metabolites IV and V, the AUC(0)-infinity was increased approximately eightfold over control values. In addition, day 1-infected mice demonstrated evidence of renal and hepatic dysfunction. In summary, C. albicans infection produced marked changes in the pharmacokinetics of pentoxifylline and its metabolites in the mice. The high concentrations of pentoxifylline and its metabolites in serum attained in infected mice may have contributed to the increased mortality of mice with systemic candidiasis.

Induction of Mn SOD in human monocytes without inflammatory cytokine production by a mutant endotoxin

Endotoxin selectively induces monocyte Mn superoxide dismutase (SOD) without affecting levels of Cu,Zn SOD, catalase, or glutathione peroxidase. However, little is known about the structure-activity relationship and the mechanism by which endotoxin induces Mn SOD. In this study we demonstrated that a mutant Escherichia coli endotoxin lacking myristoyl fatty acid at the 3' R-3-hydroxymyristate position of the lipid A moiety retained its full capacity to coagulate Limulus amoebocyte lysate compared with the wild-type E. coli endotoxin and markedly stimulated the activation of human monocyte nuclear factor-kappaB and the induction of Mn SOD mRNA and enzyme activity. However, in contrast to the wild-type endotoxin, it failed to induce significant production of tumor necrosis factor-alpha and macrophage inflammatory protein-1alpha by monocytes and did not induce the phosphorylation and nuclear translocation of mitogen-activated protein kinase. These results suggest that 1) lipid A myristoyl fatty acid, although it is important for the induction of inflammatory cytokine production by human monocytes, is not necessary for the induction of Mn SOD, 2) endotoxin-mediated induction of Mn SOD and inflammatory cytokines are regulated, at least in part, through different signal transduction pathways, and 3) failure of the mutant endotoxin to induce tumor necrosis factor-alpha production is, at least in part, due to its inability to activate mitogen-activated protein kinase.

New directions in perioperative management for pediatric solid organ transplantation

Advances in pediatric solid organ transplantation have furthered the understanding of end-organ failures and refined the strategies for perioperative management of these otherwise lethal diseases. As the donor pool expands, the number of transplantations increases and long-term survival continues to improve, more complete knowledge of the immunologic and pathologic processes will be gained. A thorough understanding of the principles of transplantation medicine remains essential for physicians to provide optimal perioperative care of pediatric organ transplant patients.

Potentiation by thyroid hormone of human IFN-gamma-induced HLA-DR expression

We have investigated the mechanism by which thyroid hormone potentiates IFN-gamma-induced HLA-DR expression. IFN-gamma-induced HLA-DR expression requires activation of STAT1alpha and induction of the Class II trans-activator, CIITA. HeLa and CV-1 cells treated only with L-thyroxine (T4) demonstrated increased tyrosine phosphorylation and nuclear translocation (= activation) of STAT1alpha; this hormone effect on signal transduction, and T4 potentiation of IFN-gamma-induced HLA-DR expression, were blocked by the inhibitors CGP 41251 (PKC) and genistein (tyrosine kinase). Treatment of cells with T4-agarose also caused activation of STAT1alpha. In the presence of IFN-gamma, T4 enhanced cytokine-induced STAT1alpha activation. Potentiation by T4 of IFN-gamma action was associated with increased mRNA for both CIITA and HLA-DR, with peak enhancement at 16 h (CIITA), and 2 d (HLA-DR). T4 increased IFN-gamma-induced HLA-DR protein 2.2-fold and HLA-DR mRNA fourfold after 2 d. Treatment with actinomycin D after induction of HLA-DR mRNA with IFN-gamma, with or without T4, showed that thyroid hormone decreased the t(1/2) of mRNA from 2.4 to 1.1 h. HeLa and CV-1 cells lack functional nuclear thyroid hormone receptor. Tetraiodothyroacetic acid (tetrac) and 3,5,3'-triiodo-thyroacetic acid (triac) blocked T4 potentiation of IFN-gamma-induced HLA-DR expression and T4 activation of STAT1alpha. These studies define an early hormone recognition step at the cell surface that is novel, distinct from nuclear thyroid hormone receptor, and blocked by tetrac and triac. Thus, thyroid hormone potentiation of IFN-gamma-induced HLA-DR transcription is mediated by a cell membrane hormone binding site, enhanced activation of STAT1alpha, and increased CIITA induction.

Long-term efficacy, tolerability, and safety of the combination of enalapril and felodipine ER in the treatment of hypertension. Enalapril-Felodipine ER Factorial Study Group

A recent 8-week, double-masked, placebo-controlled, 3 x 4 factorial-design study demonstrated that enalapril-felodipine extended-release (ER) combinations had statistically significant additive effects for reducing both sitting systolic blood pressure (SiSBP) and sitting diastolic blood pressure (SiDBP) and were generally well tolerated in hypertensive patients with SiDBPs ranging from 95 to 115 mm Hg. The present open-label study was undertaken to assess the long-term efficacy, tolerability, and safety of such combinations. Patients from the factorial study were eligible for the 1-year, open-label extension. Initially, all patients received enalapril 5 mg-felodipine ER 2.5 mg once daily; if SiDBP was not controlled (< 90 mm Hg) after 4 weeks of treatment, the dose was titrated upward at 2- to 4-week intervals to a maximum of enalapril 10 mg-felodipine ER 10 mg. Hydrochlorothiazide (HCTZ) 12.5 mg was added to the regimen of patients whose hypertension was not controlled at the highest enalapril-felodipine ER dose. A total of 507 patients were enrolled, of whom 502 were assessable. At their last study visit, 391 (78%) of the assessable patients were receiving only an enalapril-felodipine ER combination. The enalapril-felodipine ER combinations resulted in mean trough SiDBPs of 85 to 89 mm Hg (decreases of 13 to 16 mm Hg from baseline) and SiSBPs of 137 to 140 mm Hg (decreases of 13 to 21 mm Hg). Overall, 407 (81%) of the 502 assessable patients achieved an SiDBP < 90 mm Hg or a reduction from baseline > or = 10 mm Hg (responders); such a response was recorded in 331 patients (66%) taking a combination of enalapril-felodipine ER alone and 76 patients (15%) taking the combination with the addition of HCTZ 12.5 mg. Blood pressure reductions were maintained throughout the treatment period. Drug-related adverse events were relatively infrequent, often transient, usually mild, and apparently not dose related. The most frequently reported drug-related adverse events were edema/swelling, asthenia/fatigue, dizziness, cough, and headache. These results suggest that combination therapy with enalapril-felodipine ER is effective for long-term blood pressure reduction, has an excellent safety profile, and is generally well tolerated. Addition of low-dose HCTZ to the enalapril-felodipine ER combination appears to provide further blood pressure control without increasing drug-related adverse events.

Identification of epitopes within beta lactoglobulin recognised by polyclonal antibodies using phage display and PEPSCAN

Two different epitope mapping techniques were used to identify linear epitopes recognised by polyclonal IgG antibodies from rabbits immunised with bovine beta lactoglobulin (BLG), which is generally regarded as a major allergen in milk. The first, PEPSCAN, was used to investigate the binding of several rabbit polyclonal antisera to sequential overlapping peptides (12-mers) across the sequence of BLG. Each peptide was synthesized on a different polypropylene PIN, and a standard ELISA procedure was used to locate which of these peptides bound the antibodies under investigation. Comparisons of PEPSCANs for antisera from six different rabbits showed that each rabbit recognized a similar set of epitopes within BLG. PEPSCAN analysis also showed that polyclonal antibodies from the mouse recognize a set of epitopes similar to those recognized by the rabbit. The second epitope mapping technique is known as phage display and utilizes libraries of randomized short peptides fused to the coat proteins of filamentous phage as a source of epitopes for analysis. A gene VIII phage display library was used in this study with constrained nonapeptides, which were screened for epitopes recognized by affinity purified rabbit anti-BLG IgG. Immobilised rabbit anti-BLG IgG was screened in two separate experiments, each consisting of three rounds of panning. For each separate experiment, a sensitive phage ELISA was used to screen several hundred single phage clones for binding to anti-BLG IgG immobilised on microtiter plates. As a result, a number of positive phage were identified from the two separate screens of the library (19 different peptides were isolated, which resembled four different regions of BLG). The identified sequences were found to constitute a subset of the linear epitopes recognized by the PEPSCAN technique. The coordinates of the crystal structure of BLG were used to display mapped epitopes on its structure. This study has permitted detailed mapping of the major linear antigenic regions within BLG recognised by IgG antibodies from immunised rabbits and mice.

The effects of pentoxifylline infusion on plasma 6-keto-prostaglandin F1 alpha and ex vivo endotoxin-induced tumour necrosis factor activity in horses

Pentoxifylline (7.5 mg/kg) was bolused intravenously to eight healthy horses and was immediately followed by infusion (1.5 mg/kg/h) for 3 h. Clinical parameters were recorded and blood samples were collected for 24 h. Plasma was separated and concentrations of pentoxifylline, its reduced metabolite I, and 6-keto-prostaglandin F1 alpha were determined. Heparinized whole blood was also incubated ex vivo with 1 ng Escherichi coli endotoxin/mL blood for 6 h before determination of plasma tumour necrosis factor activity. The peak plasma concentrations of pentoxifylline and metabolite I occurred at 15 min after bolus injection and were 9.2 +/- 1.4 and 7.8 +/- 4.3 micrograms/mL, respectively. The half-life of elimination (t1/2 beta) of pentoxifylline was 1.44 h and volume of distribution (Vdarea) was 0.94 L/kg. The mean plasma concentration of 6-keto-prostaglandin F1 alpha increased over time, with a significant increase occurring 30 min after the bolus administration. Ex vivo plasma endotoxin-induced tumour necrosis factor activity was significantly decreased at 1.5 and 3 h of infusion. These results indicate that infusion of pentoxifylline will increase 6-keto-prostaglandin F1 alpha and significantly suppress endotoxin-induced tumour necrosis factor activity in horses during the period of infusion.

Protein synthesis-dependent potentiation by thyroxine of antiviral activity of interferon-gamma

We have studied the prenuclear signal transduction pathway by which thyroid hormone potentiates the antiviral activity of human interferon-gamma (IFN-gamma) in HeLa cells, which are deficient in thyroid hormone receptor (TR). The action of thyroid hormone was compared with that of milrinone, which has structural homologies with thyroid hormone. L-Thyroxine (T4), 3,5,3'-L-triiodothyronine (T3), and milrinone enhanced the antiviral activity of IFN-gamma up to 100-fold, a potentiation blocked by cycloheximide. The 5'-deiodinase inhibitor 6-n-propyl-2-thiouracil did not block the T4 effect. 3,3',5,5'-Tetraiodothyroacetic acid prevented the effect of T4 but not of milrinone. The effects of T4 and milrinone were blocked by inhibitors of protein kinases C (PKC) and A (PKA) and restored by PKC and PKA agonists; only the effect of T4 was blocked by genistein, a tyrosine kinase inhibitor. In separate models, milrinone was shown not to interact with nuclear TR-beta. T4 potentiation of the antiviral activity of IFN-gamma requires PKC, PKA, and tyrosine kinase activities but not traditional TR.

Single-dose ondansetron prevents postoperative vomiting in pediatric outpatients

This randomized, double-blind, parallel-group, multicenter study evaluated the safety and efficacy of ondansetron (0.1 mg/kg to 4 mg intravenously) compared with placebo in the prevention of postoperative vomiting in 429 ASA status I-III children 1-12 yr old undergoing outpatient surgery under nitrous oxide- and halothane-based general anesthesia. The results show that during both the 2-h and the 24-h evaluation periods after discontinuation of nitrous oxide, a significantly greater percentage of ondansetron-treated patients (2 h 89%, 24 h 68%) compared with placebo-treated patients (2 h 71%, 24 h 40%) experienced complete response (i.e., no emetic episodes, not rescued, and not withdrawn; P < 0.001 at both time points). Ondansetron-treated patients reached criteria for home readiness one-half hour sooner than placebo-treated patients (P < 0.05). The age of the child, use of intraoperative opioids, type of surgery, and requirement to tolerate fluids before discharge may also have affected the incidence of postoperative emesis during the 0- to 24-h observation period. Use of postoperative opioids did not have any effect on complete response rates in this patient population. We conclude that the prophylactic use of ondansetron reduces postoperative emesis in pediatric patients, regardless of the operant influential factors.

IMPLICATIONS

Postoperative nausea and vomiting often occur after surgery and general anesthesia in children and are the major reason for unexpected hospital admission after ambulatory surgery. Our study demonstrates that the prophylactic use of a small dose of ondansetron reduces postoperative vomiting in pediatric patients.

Cholesterol in condensed and fluid phosphatidylcholine monolayers studied by epifluorescence microscopy

Epifluorescence microscopy was used to investigate the effect of cholesterol on monolayers of dipalmitoylphosphatidylcholine (DPPC) and 1 -palmitoyl-2-oleoyl phosphatidylcholine (POPC) at 21 +/- 2 degrees C using 1 mol% 1-palmitoyl-2-[12-[(7-nitro-2-1, 3-benzoxadizole-4-yl)amino]dodecanoyl]phosphatidylcholine (NBD-PC) as a fluorophore. Up to 30 mol% cholesterol in DPPC monolayers decreased the amounts of probe-excluded liquid-condensed (LC) phase at all surface pressures (pi), but did not effect the monolayers of POPC, which remained in the liquid-expanded (LE) phase at all pi. At low pi (2-5 mN/m), 10 mol% or more cholesterol in DPPC induced a lateral phase separation into dark probe-excluded and light probe-rich regions. In POPC monolayers, phase separation was observed at low pi when > or =40 mol% or more cholesterol was present. The lateral phase separation observed with increased cholesterol concentrations in these lipid monolayers may be a result of the segregation of cholesterol-rich domains in ordered fluid phases that preferentially exclude the fluorescent probe. With increasing pi, monolayers could be transformed from a heterogeneous dark and light appearance into a homogeneous fluorescent phase, in a manner that was dependent on pi and cholesterol content. The packing density of the acyl chains may be a determinant in the interaction of cholesterol with phosphatidylcholine (PC), because the transformations in monolayer surface texture were observed in phospholipid (PL)/sterol mixtures having similar molecular areas. At high pi (41 mN/m), elongated crystal-like structures were observed in monolayers containing 80-100 mol% cholesterol, and these structures grew in size when the monolayers were compressed after collapse. This observation could be associated with the segregation and crystallization of cholesterol after monolayer collapse.

Microbial models of mammalian metabolism. Biotransformations of HP 749 (besipirdine) using Cunninghamella elegans

HP 749 (besipirdine; Hoechst-Roussel Pharmaceuticals, Inc., Somerville, NJ) and related analogs belonging to the N-(4-pyridinyl)-1H-indol-1-amine class of compounds have shown a potential to mitigate multiple biochemical deficits associated with Alzheimer's disease. HP 749 has demonstrated cholinergic and nonadrenergic activities both in vitro and in vivo, and has potential for the symptomatic treatment of Alzheimer's disease. The three primary metabolites of HP 749 in dogs, rats, and humans result from hydroxylation of the indole ring, N-dealkylation of the parent compound, and sequential hydroxylation and dealkylation. The fungus Cunninghamella elegans (ATCC 36112) converts 25% of HP 749 in a dextrose broth to yield four metabolites, three of which have been reported in mammalian systems. Preparative scale fermentation allowed for the isolation of the major fungal metabolite resulting from hydroxylation of the indole nucleus at position 5 (16%), which was characterized by cochromatographic (TLC and HPLC), 1H-NMR, mass spectral (chemical ionization/MS), and UV comparisons to a synthetic standard. Additional minor fungal metabolites were formed as a result of N-dealkylation (2%), and sequential N-dealkylation and aromatic hydroxylation (2.5%). C. elegans is being used as a model to help predict and generate the logical mammalian metabolites of related structural analogs of HP 749.

A randomized multicenter study of remifentanil compared with alfentanil, isoflurane, or propofol in anesthetized pediatric patients undergoing elective strabismus surgery

Remifentanil hydrochloride is a new, ultrashort-acting opioid metabolized by nonspecific plasma and tissue esterases. We conducted this multicenter study to examine the hemodynamic response and recovery profile of premedicated children undergoing strabismus repair who were randomly assigned to receive one of four treatment drugs (remifentanil, alfentanil, isoflurane, or propofol) along with nitrous oxide and oxygen for maintenance of anesthesia. Induction of anesthesia was by nitrous oxide, oxygen, and halothane or nitrous oxide, oxygen, and propofol. Anesthesia was then maintained with remifentanil 1.0 microgram/kg over 30-60 s, followed by a constant infusion of 1.0 microgram.kg-1.min-1, alfentanil 100 micrograms/kg bolus followed by a constant infusion of 2.5 micrograms.kg-1.min-1, propofol 2.5 mg/kg bolus followed by a constant infusion of 200 micrograms.kg-1.min-1, or isoflurane 1.0 minimum alveolar anesthetic concentration. The infusions of the anesthetics and the administration of the inhaled gases were adjusted clinically by predetermined protocols. Elapsed time intervals from the end of surgery to the time the patients were tracheally extubated and displayed purposeful movement, as well as the time the patients met the postanesthesia care unit (PACU) and hospital discharge times, were recorded. Heart rate and systolic and diastolic blood pressure were measured at fixed intervals. In addition, cardiovascular side effects (bradycardia, hypotension, and hypertension) as well as vomiting, pruritus, agitation, and postoperative hypoxemia were also noted. There were no significant differences in patient demographics among the treatment groups. There was no difference in the early recovery variables (times to extubation and purposeful movement) or the times to PACU and hospital discharge among groups. There were significant differences in side effects among the groups. Patients who received remifentanil had higher PACU objective pain-discomfort scores than those who received alfentanil and propofol. Patients anesthetized with alfentanil had a greater incidence in the use of naloxone and a greater incidence of postoperative hypoxemia compared with those anesthetized with remifentanil. The incidence of postoperative hypoxemia was the same for remifentanil, propofol, and isoflurane groups. There were no significant differences in the incidence of emesis among the four groups, and all four groups had similar hemodynamic profiles. We conclude that remifentanil appears to be an effective drug for anesthesia. Its hemodynamic and recovery profile appear similar to other comparable drugs. Based on previous pharmacokinetic studies, the 1.0 microgram.kg-1.min-1 infusion may be twice the 50% effective dose observed in adults. In this study, the relative "overdose" of remifentanil was well tolerated and did not prolong recovery.

Time course and involvement of protein kinase C-mediated phosphorylation of F1/GAP-43 in area CA3 after mossy fiber stimulation

1. Protein kinase C (PKC) activity and phosphorylation of F1/growth associated protein (GAP)-43, a PKC substrate, have been proposed to play key roles in the maintenance of long-term potentiation (LTP) at the synapses of Schaffer collateral/commissural on pyramidal neurons in CA1 (Akers et al., 1986). We have studied in the involvement of PKC and PKC-dependent protein phosphorylation of F1/GAP-3 in in vitro LTP observed at the synapses of mossy fiber (MF) on CA3 pyramidal neurons of rat hippocampus by post hoc in vitro phosphorylation. 2. After LTP was induced in CA3 in either the presence or absence of D-2-amino-5-phosphonovaleric acid (AP5), an NMDA receptor antagonist, the CA3 region was dissected for in vitro phosphorylation assay. In vivo phosphorylation of F1/GAP-43 was increased in membranes at 1 and 5 min after tetanic stimulation (TS) but not at 60 min after TS. 3. The degree of phosphorylation of F1/GAP-43 in the cytosol was inversely related to that in membranes at each time point after LTP. 4. The similar biochemical changes obtained from either control slices or AP5-treated slices indicate that LTP and the underlying biochemical changes are independent of the NMDA receptor. Immunoreactivity of the phosphorylated F1/GAP-43 in LTP slices was not significantly different from control, indicating that results from western blotting and post hoc in vitro phosphorylation are consistent. 5. Post hoc in vitro phosphorylation of F1/GAP-43 was PKC-mediated since phosphorylation of F1/GAP-43 was altered by the PKC activation cofactors, Ca2+, phosphatidylserine and phorbol ester. 6. Calmodulin (CaM) at > 5 microM inhibited phosphorylation, consistent with the presence of CaM-binding activity at the site on F1/GAP-43 acted upon by PKC. 7. We conclude that phosphorylation of F1/GAP-43 is associated with the induction but not the maintenance phase of MF-CA3 LTP.

Structure of a glycoconjugate in solution and in complex with an antibody Fv fragment

By use of heteronuclear (13C, 1H) NMR methods, the three-dimensional structure and dynamics of the glycoconjugate estrone-3-glucuronide (E3G) uniformly 13C enriched in the glucuronic acid moiety has been probed both in free solution and in association with an anti-E3G antibody single-chain Fv fragment. The glycan is found to exist in multiple conformations in free solution, with particularly large torsional fluctuations about the glycosidic linkage psi. Resonance assignments and distance restraints for the glycoconjugate in the bound state were obtained from heteronuclear proton-carbon-carbon-proton-COSY and isotope-edited NOESY techniques, respectively. Quantitation of the NOE data with a full-relaxation matrix approach showed that the antibody selects a conformation from the solution repertoire which does not correspond with either of the two lowest energy conformations of the free glycan, and the internal energy of the glycan in the bound state is estimated to be at most approximately 15 kcal/mol higher than the global minimum energy conformation. The glucuronide moiety undergoes a stacking interaction with an aromatic ring in the binding site, and both ring-current shifts and nuclear Overhauser effects computed from the predicted bound-state conformation are in good agreement with experiment. The bound-state conformation is also in good agreement with preliminary x-ray data on a related complex.

Cortisol pharmacodynamics after methylprednisolone administration in young and elderly males

Glucocorticoids are commonly prescribed in the elderly on an empiric basis with little consideration for the age-related alterations in pharmacologic response. The objectives of this study were to compare the effect of methylprednisolone on cortisol patterns in elderly and young healthy men, to define the relationship between pharmacokinetic parameters of methylprednisolone and pharmacodynamics of cortisol in the elderly and young men. Seven healthy, elderly males (69-82 years old) and five healthy, young males (24-37 years old) participated in a 24-hour pharmacodynamic trial with randomized assignment to a control period (Phase 1) and a methylprednisolone period (Phase II). Serial blood samples were obtained throughout both study periods. Cortisol measurements included the total area under the concentration-time curve (AUC), return AUC, and suppression ratio. During Phase I, a circadian pattern was noted in both groups. After exposure to methylprednisolone (Phase II), a linear decline in serum concentrations of cortisol was observed in both groups. The return AUC of cortisol (425 +/- 357 ng.hr/mL [elderly] versus 854 +/- 216 ng.mL [young]) and the total AUC 764 +/- 340 ng.h/mL [elderly] versus 1,230 +/- 258 ng.hr/mL [young]) were significantly lower in the older men. In addition, a significant decline in total AUC and nadir concentration of cortisol from Phase I to Phase II was noted within both groups. The suppression ratio was significantly greater in the elderly men (mean, 0.38 versus 0.58 in young), which indicates a greater degree of adrenal suppression after administration of methylprednisolone. Exposure to methylprednisolone, as measured by AUC, was 554 +/- 215 ng.hr/kg (elderly) and 389 +/- 102 ng.hr/kg (young). The greater exposure to methylprednisolone noted in the elderly yielded significant combined correlations for both groups with AUC, return AUC, and suppression ratio of cortisol. A more significant response of cortisol to the exogenous glucocorticoid was apparent in the elderly men. In addition, a slower clearance of methylprednisolone was noted in the elderly group compared with their young counterparts. The effect of reduced clearance of methylprednisolone on the suppression ratio indicates the interrelationship between the disposition of a single dose of an exogenous glucocorticoid and response patterns of cortisol.

Combined enalapril and felodipine extended release (ER) for systemic hypertension. Enalapril-Felodipine ER Factorial Study Group

This multicenter, placebo-controlled, double-blind trial of factorial design evaluated the safety and efficacy of combination treatment with the angiotensin-converting enzyme inhibitor, enalapril, and the vascular selective calcium antagonist felodipine extended release (ER) in patients with essential hypertension. After a 4-week, single-blind placebo baseline period, 707 patients with sitting diastolic blood pressures (BPs) in the range of 95 to 115 mm Hg received placebo, enalapril (5 or 20 mg), felodipine ER (2.5, 5, or 10 mg), or their combinations for an 8-week double-blind treatment period. All doses of enalapril and felodipine ER had a statistically significant (p < 0.05) additive effect in reducing both systolic and diastolic BP. The trough to peak ratios for the combinations ranged from 0.63 (enalapril 5 mg-felodipine ER 2.5 mg) to 0.79 (enalapril 20 mg-felodipine ER 10 mg) and were consistent with effective BP control with 1 dose/day. Patients aged > or = 65 years demonstrated a greater reduction in diastolic BP. Combinations of enalapril-felodipine ER were associated with less drug-induced peripheral edema (4.1%) compared to felodipine ER monotherapy (10.8%). There were no serious drug-related adverse effects observed during the study. In this trial, the combination of enalapril and felodipine ER effectively lowered BP and was generally well tolerated with an excellent safety profile when used in the treatment of hypertension.

Fentanyl and alfentanil plasma protein binding in preterm and term neonates

The effects of gestational age (GA) and plasma protein concentrations on the plasma protein binding of fentanyl and alfentanil were studied in preterm and term neonates. Binding experiments were performed using split-cell equilibrium dialysis. Fentanyl and alfentanil concentrations were measured using specific radioimmunoassay, and the proteins albumin and alpha-1-acid glycoprotein (AAG) were measured using radial immunodiffusion assays. In the preterm neonates, 77% of fentanyl and 65% of alfentanil was bound. In the term neonates, 70% of fentanyl and 79% of alfentanil was bound. The binding ratio of alfentanil showed a positive correlation with gestational age and AAG concentration. The binding ratio of fentanyl showed a weak, negative correlation with gestational age. These data indicate that fentanyl and alfentanil are not interchangeable at the GA studied because of age-related changes in protein binding.

Speech breathing and the Lombard effect

Respiratory measurements were made using linearized magnetometers placed antero-posteriorly over the rib cages and abdomens of five healthy young women. Background noise was introduced over headphones simultaneously as "babble" presented binaurally at 55 dB ("moderate noise") and 70 dB ("high noise"). Speech during oral reading and spontaneous monologue was transduced with a microphone positioned near the lips, from which a speaking intensity signal (dBA) was derived. Subjects were instructed to speak during the noise conditions, but no instruction was given to alter speaking intensity. Compared with a "no noise" condition, the speaking intensities of all the subjects increased significantly for both speech tasks in the moderate and high noise conditions, thereby replicating the well-documented Lombard effect. No consistent trend of lung volume change was observed, in contrast to the linear increases in speech intensity as the noise level increased. For the higher speech intensities during the moderate and high noise conditions both initiation and termination lung volumes either increased or decreased. These preliminary findings suggest that when speech intensity is increased following the introduction of noise via headphones rather than by specific instruction to speak more loudly, speakers employ variable lung volume strategies for intensity control.

Thermal history alters cholesterol effect on transition of 1-palmitoyl-2-linoleoyl phosphatidylcholine

The effect of cholesterol on the bilayer phase behavior of heteroacid phosphatidylcholines with one unsaturated fatty acid depends on the nature of the unsaturated chain. Previous differential scanning calorimetry (DSC) studies showed that 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphocholine (16:0-18:2 PC) had a broad, weak transition at about -18 degrees C, which was effectively eliminated by less than 15 mol% cholesterol. Phospholipids with greater and lesser degrees of unsaturation displayed stronger phase transitions and less sensitivity to cholesterol. In this work, deuterium nuclear magnetic resonance has been used to examine the phase behavior of 1-perdeuteriopalmitoyl-2-linoleoyl-sn-glycero-3-phosphocholine (16:0-18:2 PC-d31) alone, and with 15 mol % cholesterol. The behavior is found to be sensitive to sample thermal history. Moderately fast cooling (1 degree/h) results in a continuous phase change from a fluid to an ordered phase in the pure lipid. Under similar cooling conditions, the sample containing cholesterol displays increased chain order and a continuous phase change with no apparent isothermal transition. However, when these systems are cooled at a reduced rate (0.3 degree/h), the continuous phase change is pre-empted by a sharp transition into a more ordered phase that gives a deuterium spectrum having intensity at a value of the quadrupole-splitting characteristic of a rigid lattice system. In the pure lipid, this transition effectively coincides with the center of the continuous phase change. Addition of 15 mol % cholesterol lowers the temperature of this sharp transition by about 3 degrees C. These observations provide some insights into the behavior of this system seen using differential scanning calorimetry. Results of deuteron transverse relaxation measurements under these conditions are also reported.

Molecular modelling study of the binding of inhibitors of aromatase to the cytochrome P-450 heme

A novel molecular modelling study, involving inhibitors bound to a 'substrate-heme complex', is described for steroidal and non-steroidal inhibitors of Aromatase (AR). Results with azole compounds such as CGS-16949A, and its derivatives, agree with recently reported studies that these compounds appear to utilise the steroid C(17) carbonyl binding region of the active site as opposed to the steroid C(3) carbonyl binding region. The study of Aminoglutethimide (AG) type compounds, however, suggests that they mimic the steroid C(17) and not the C(3) carbonyl group as suggested by previous workers. However, results with inhibitors based on pyridine ligands such as 3-(4'-pyridyl)-3-ethyl piperidine-2, 6-dione (PYG), suggest that these compounds utilise the steroid C(3) carbonyl binding region and therefore agrees with previous reports. Consideration of the orientation of the R and S enantiomers of PYG is, however, found to be a reversal of that previously reported. Using inhibitors bound to the 'substrate-heme complex', and data from previous studies of derivatives of androstenedione, reasons for differences in activity of enantiomers of AG, PYG, N-octyl-3-(4'-pyridyl)-3-ethyl piperidine-2, 6-dione, and 10-thiiranylestr-4-ene-3, 17-dione, as well as other potent and less potent inhibitors, are put forward.

Potentiation by thyroxine of interferon-gamma-induced antiviral state requires PKA and PKC activities

Added to HeLa cells previously exposed to recombinant human interferon (IFN)-gamma for 20 h, thyroid hormone [L-thyroxine (T4)] in physiological concentrations potentiates the antiviral action of IFN-gamma by more than 100-fold in 4 h. We examined protein kinase activities for their contributions to the mechanism of this posttranslational effect of thyroid hormone. Added concurrently with thyroid hormone, the protein kinase C (PKC) inhibitor CGP-41251 (5 nM) blocked T4 potentiation of IFN-gamma action. Coincubated with CGP-41251, phorbol 12-myristate 13-acetate (PMA) reversed the effect of the inhibitor on thyroid hormone action. U-73122 (10 nM), a phospholipase C inhibitor, also blocked hormone potentiation. KT-5720 (500 nM), a protein kinase A (PKA) inhibitor, completely inhibited the T4 effect, whereas 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) restored hormone action in the presence of KT-5720. In the absence of T4, 8-BrcAMP and PMA, added together to cells in the 4-h paradigm, fully reproduced hormone potentiation of the antiviral effect of IFN-gamma. Incubated individually with IFN-gamma-treated cells, the two agonists had no potentiating action. Thyroid hormone apparently must activate both PKA and PKC in the nongenomic pathway of IFN-gamma action to enhance antiviral activity in HeLa cells.

Nongenomic actions of thyroid hormone

Nongenomic actions of thyroid hormone are by definition independent of nuclear receptors for the hormone and have been described at the plasma membrane, various cell organelles, the cytoskeleton, and in cytoplasm. The actions include alterations in solute transport (Ca2+, Na+, glucose), changes in activities of several kinases, including protein kinase C, cAMP-dependent protein kinase and pyruvate kinase M2 (PKM2), effects on efficiency of specific mRNA translation and mRNA t1/2, modulation of mitochondrial respiration, and regulation of actin polymerization (promotion of formation of F-actin). Iodothyronines also can regulate nongenomically the state of contractile elements in vascular smooth muscle cells (VSMC). The physiologic significance at the cellular level of certain of these actions has been demonstrated, for example, in the cases of myocardiocyte Na+ current, red cell Ca2+ content, and the control by hormone-induced alterations in actin solubility of cell surface activity of iodothyronine 5'-monodeiodinase activity and the intracellular distribution of protein disulfide isomerase activity. The physiologic significance of these actions at the organ or system level is less clear, but extranuclear effects of thyroid hormone on myocardial Na+ channel, sarcoplasmic reticulum Ca(2+)-ATPase activity, and contractile state of VSMC may each contribute to acute effects of thyroid hormone on cardiac output that have recently been described clinically. The molecular mechanisms for nongenomic actions are incompletely understood; relevant binding sites and signal transduction pathways have been described for hormone actions on plasma membrane Ca(2+)-ATPase activity, and PKM2 monomer is known to bind T3 and, as a result, prevent activation of the kinase via tetramer formation. Nongenomic actions of thyroid hormone may have different structure-activity relationships of iodothyronines from those effects that depend upon nuclear receptors; they may have different time courses and may invoke complex signal transduction pathways before the action is detected.

Induction, recovery, and safety characteristics of sevoflurane in children undergoing ambulatory surgery. A comparison with halothane

BACKGROUND

Sevoflurane is an inhalational anesthetic with characteristics suited for use in children. To determine whether the induction, recovery, and safety characteristics of sevoflurane differ from those of halothane, the following open-labeled, multicenter, randomized, controlled, phase III study in children undergoing ambulatory surgery was designed.

METHODS

Three hundred seventy-five children, ASA physical status 1 or 2, were randomly assigned in a 2:1 ratio to receive either sevoflurance or halothane, both in 60% N2O and 40% O2. Anesthesia was induced using a mask with an Ayre's t piece or Bain circuit in four of the centers and a mask with a circle circuit in the fifth center. Maximum inspired concentrations during induction of anesthesia were 7% sevoflurane and 4.3% halothane. Anesthesia was maintained by spontaneous ventilation, without tracheal intubation. End-tidal concentrations of both inhalational anesthetics were adjusted to 1.0 MAC for at least 10 min before the end of surgery. Induction and recovery characteristics and all side effects were recorded. The plasma concentration of inorganic fluoride was measured at induction of and 1 h after anesthesia.

RESULTS

During induction of anesthesia, the time to loss of the eyelash reflex with sevoflurane was 0.3 min faster than with halothane (P < 0.001). The incidence of airway reflex responses was similar, albeit infrequent with both anesthetics. The total MAC.h exposure to sevoflurane was 11% less than the exposure to halothane (P < 0.013), although the end-tidal MAC multiple during the final 10 min of anesthesia was similar for both groups. Early recovery as evidenced by the time to response to commands after sevoflurane was 33% more rapid than it was after halothane (P < 0.001), although the time to discharge from hospital was similar for both anesthetics. The mean ( +/- SD) plasma concentration of inorganic fluoride 1 h after discontinuation of sevoflurane was 10.3 +/- 3.5 microM. The overall incidence of adverse events attributable to sevoflurane was similar to that of halothane, although the incidence of agitation attributable to sevoflurane was almost threefold greater than that attributable to halothane (P < 0.004).

CONCLUSIONS

Sevoflurane compared favorably with halothane. Early recovery after sevoflurane was predictably more rapid than after halothane, although this was not reflected in a more rapid discharge from the hospital. The incidence of adverse events was similar for both anesthetics. Clinically, the induction, recovery, and safety characteristics of sevoflurane and halothane are similar. Sevoflurane is a suitable alternative to halothane for use in children undergoing minor ambulatory surgery.

Thyroid hormone analogues potentiate the antiviral action of interferon-gamma by two mechanisms

L-thyroxine (L-T4) potentiates the antiviral activity of human interferon-gamma (IFN-gamma) in HeLa cells. We have added thyroid hormone and analogues to cells either 1) for 24 h pretreatment prior to 24 h of IFN-gamma (1.0 IU/ml), 2) for 24 h cotreatment with IFN-gamma, 3) for 4, after 20 h cell incubation with IFN-gamma, alone, or 4) for 24 h pretreatment and 24 h cotreatment with IFN-gamma. The antiviral effect of IFN-gamma was then assayed. L-T4 potentiated the antiviral action of IFN-gamma by a reduction in virus yield of more than two logs, the equivalent of a more than 100-fold potentiation of the IFN's antiviral effect. 3,3 of the IFN's antiviral effect. 3,3',5-L-triiodothyronine (L-T3) was as effective as L-T4 when coincubated for 24 h with IFN-gamma but was less effective than L-T4 when coincubated for only 4 h. D-T4, D-T3, 3,3',5-triiodothyroacetic acid (triac), tetraiodothyroacetic acid (tetrac), and 3,5-diiodothyronine (T2) were inactive. When preincubated with L-T4 for 24 h prior to IFN-gamma treatment, tetrac blocked L-T4 potentiation, but, when coincubated with L-T4 for 4 h after 20 h IFN-gamma, tetrac did not inhibit the L-T4 effect. 3,3',5-L-triiodothyronine (rT3) also potentiated the antiviral action of IFN-gamma, but only in the preincubation model. Furthermore, the effects of rT3 preincubation and L-T3 coincubation were additive, resulting in 100-fold potentiation of the IFN-gamma effect. When L-T4, L-T3, or rT3, plus cycloheximide (5 micrograms/ml), was added to cells for 24 h and then removed prior to 24 h IFN-gamma exposure, the potentiating effect of the three iodothyronines was completely inhibited. In contrast, IFN-gamma potentiation by 4 h of L-T4 or L-T3 coincubation was not inhibited by cycloheximide (25 micrograms/ml). These studies demonstrate two mechanisms by which thyroid hormones can potentiate IFN-gamma's effect: 1) a protein synthesis-dependent mechanism evidenced by enhancement of IFN-gamma's antiviral action by L-T4, L-T3, or rT3 preincubation, and inhibition of enhancement by tetrac and cycloheximide, and 2) a protein synthesis-independent (posttranslational) mechanism, not inhibited by tetrac or cycloheximide, demonstrated by 4 h coincubation of L-T4 or L-T3, but not rT3, with IFN-gamma. The protein synthesis-dependent pathway is responsive to rT3, a thyroid hormone analogue generally thought to have little effect on protein synthesis. A posttranslational mechanism by which the antiviral action of IFN-gamma can be regulated has not previously been described.

Increased plasma IGF-1 levels but lack of changes in adipocyte glucose transport in weanling rats with dorsomedial hypothalamic nucleus lesions 1 year after lesion production

Experimental destruction of the dorsomedial hypothalamic nuclei (DMN) in weanling rats exerts an antiaging effect by preventing microalbuminuria and kidney lesions both 1 month and 1 year after lesion production. In the present study we report further on antiaging effects of DMN lesions (DMNL) by measuring glucose transport into adipocytes and plasma levels of insulin-like growth factors 1 and 2 (IGF-I, IGF-II). Male and female weanling Sprague-Dawley rats received bilateral electrolytic lesions in the DMN; sham-operated animals served as controls (SCON). The rats were maintained for 1 year and food intake was measured 3 weeks after surgery and 3 weeks prior to sacrifice. As expected, DMNL resulted in profound reductions of body weight and food intake, with male DMNL rats showing higher body weights and body weight gains than their female counterparts. The same was true of the respective SCON. In male DMNL rats, carcass fat in absolute terms was significantly reduced vs. SCON, but it was comparable among all groups when expressed in percent. Lean body mass (LBM), although significantly reduced in absolute terms in DMNL rats vs. SCON, was, however, significantly higher in male DMNL vs. SCON when expressed in percent, but not in females. LBM laid down per food energy taken in was higher in DMNL rats of both sexes than in their respective SCON. Efficiency of food utilization was normal in male DMNL vs. male SCON but was higher in female DMNL vs. SCON. Both male and female DMNL rats had significantly higher plasma IGF-1 concentrations than their respective SCON, and male DMNL rats had higher values than female DMNL rats. Plasma concentrations of IGF-II were significantly higher in DMNL vs. SCON, but only in females. Under both basal and insulin-stimulated conditions, DMNL rats had normal 3-0-methylglucose flux in adipocytes from epididymal fat pads vs. SCON. However, DMNL and SCON responded similarly to the stimulating effect of insulin. Although one-year-old rats may not be considered "aged", we do consider the observed lack of a drop in plasma IGF-I levels that occurs with aging as an "anti-aging" effect of DMN lesions.

Sequence of the nucleocapsid protein gene of subgroup A and B avian pneumoviruses

The nucleocapsid protein (N) gene of two subgroup A and one subgroup B strains of avian pneumovirus has been cloned and sequenced. The gene of all three isolates comprised 1197 nucleotides (nt), which formed a single major open reading frame, potentially encoding a protein of 391 amino acid residues. The N gene of the two subgroup A isolates differed by only 1 nt but differed by 282 (24%) nt and 35 (11%) amino acids from the B isolate. The predicted protein was identical in length to that of human, bovine and ovine respiratory syncytial viruses, the amino acid identity being approximately 41% overall but with some regions of identity > 90%.

Neural control of vocalization: respiratory and emotional influences

Previous research has shown that a region of the midbrain, the periaqueductal gray matter (PAG), is critical for vocalization. In this review, we describe the results of previous investigations in which we sought to find out how PAG neurons integrate the activity and precise timing of respiratory, laryngeal, and oral muscle activity for natural-sounding vocalization using the technique of excitatory amino acid microinjections in cats. In these studies, all surgical procedures were carried out under deep anaesthesia. In the precollicular decerebrate cat two general types of vocalization, classified as voiced and unvoiced, could be evoked by exciting neurons in the lateral part of the intermediate part of the PAG. The patterns of evoked electromyographic activity were strikingly similar to previously reported patterns of human muscle activity. Coordinated patterns of activity were evoked with just-threshold excitation leading to the conclusion that patterned muscle activity corresponding to the major categories of voiced and voiceless sound production are represented in the PAG. In a parallel series of human and animal experiments, we also determined that the speech and vocalization respiratory patterns are integrated and coordinated with afferent signals related to lung volume. These data have led to the proposal of a new hypothesis for the neural control of vocalization: that the PAG is a crucial brain site for mammalian voice production, not only in the production of emotional or involuntary sounds, but also as a generator of specific respiratory and laryngeal motor patterns essential for human speech and song.

Aging and the hypothalamus: research perspectives

There are several hypothalamic theories of aging, none of which has been validated. An approach to validation is to search for consequences of anatomic ablations of hypothalamic regions that are functional hallmarks of aging, or consequences of ablation that postpone the appearance of hallmarks of aging or extend longevity. Ablation of the hypothalamic ventromedial nucleus (VMN) in the weanling rat is associated with subsequent increased body fat, glucose intolerance, hyperlipidemia, and decreased renal function. Each of these consequences is characteristic of aging in humans and in several animal models of aging. Ablation of the hypothalamic dorsomedial nucleus (DMN) in the weanling rat leads to a symmetrically smaller animal with normal glucose and lipid metabolism, decreased body fat for size, and reduced risk of decreased renal function and circulating IGF-I levels. These are findings consistent with calorie restriction models in rodents that significantly extend life span. This review compares outcomes of lesions in the VMN, DMN, and lateral hypothalamic area (LHA) for relevance to aging. To establish a relationship between these anatomic areas of the hypothalamus and aging, it is concluded that the VMN, DMN, and LHA lesions should be examined for impact on longevity and compared with data obtained from simultaneously studied intact ad-lib-fed and 40% calorie-restricted animals. Lesioned animals also should be rigorously studied for neurotransmitters (e.g., neuropeptide Y, beta-endorphin, serotonin, corticotropin-releasing factor, and galanin), and for behavioral changes consistent with aging, for accumulation of specific tissue lipofuscin and amyloid that are associated with normal aging and for other age-dependent findings, such as incidence of tumors and cataract.

Potentiation by thyroxine of interferon-gamma-induced HLA-DR expression is protein kinase A- and C-dependent

L-Thyroxine (T4) and 3,3',5-L-triiodothyronine (T3) potentiate the antiviral state induced by interferon-gamma(IFN-gamma) in homologous cells by a mechanism that is dependent upon calcium/phospholipid-dependent protein kinase (PKC). L-T4 and T3 also potentiate induction by IFN-gamma of MHC class II HLA-DR antigen expression in HeLa cells. In the present studies of HLA-DR expression, the PKC inhibitor staurosporine (0.1-1 nM) enhanced the expression of HLA-DR when the inhibitor was added simultaneously with IFN-gamma, 100 IU/ml. In the presence of IFN-gamma and 10(-7) M T4, the same concentrations of staurosporine inhibited potentiation of HLA-DR expression by thyroid hormone. A more specific PKC inhibitor, CGP41251 (0.5-5 nM), similarly enhanced HLA-DR expression in the presence of IFN-gamma but inhibited thyroid hormone potentiation of antigen expression. Both actions of CGP41251 were suppressed when cells were also treated with phorbol 12-myristate 13-acetate (PMA). A phospholipase C inhibitor, U73122 (1-1000 nM), did not alter the potentiating ability of T4, although it inhibited in a concentration-dependent manner the expression of HLA-DR induced by IFN-gamma. The potentiating effect of T4 was much more sensitive to a cyclic AMP-dependent protein kinase (PKA) inhibitor,KT5720 (1-1000nM), than was the induction of HLA-DR by IFN-gamma. The inhibitory effects of KT5720 were reversed by concurrent 8-bromo-cAMP treatment. The calmodulin antagonist W-7 (5-50 microM) did not alter IFN-gamma induction of HLA-DR in either the presence or absence of T4. HLA-DR expression in HeLa cells appears to be under PKC-associated inhibition; IFN-gamma reverses this inhibition to promote the appearance of the DR antigen. In contrast, potentiation by T4 of induction of HLA-DR by IFN-gamma requires activation of PKC. PKA is involved both in DR induction by IFN-gamma and in potentiation of the latter by T4. Thus, PKA and PKC have discrete roles in IFN-gamma-induced MHC class II antigen expression and its modulation by thyroid hormone.

The effects of cold, touch, and chemical stimulation of the anterior faucial pillar on human swallowing

Cold stimulation of the oropharyngeal mucosa, including the faucial pillar region, is used a specific technique for the treatment of swallowing disorders. The physiological mechanisms underpinning this clinical technique are unclear. Thermal (cold), chemical (saline, glucose and water), mechanical (light touch) and feigned stimulation of the faucial pillar were assessed for their effects on the latency to swallow and the repetitive frequency of swallowing. There was no significant difference between these variables following light stimulation of the faucial pillar with a metal probe warmed to body temperature compared with feigned stimulation. However, cold touch stimulation evoked a significant increase in swallowing latency and repetitive frequency compared to feigned stimulation. The results suggest the existence of thermo-sensitive receptors in the faucial pillars that evoke swallowing when stimulated by cold touch. The clinical and physiological importance of these findings are discussed.

Brain stem integration of vocalization: role of the nucleus retroambigualis

1. The descending pathways that mediate the periaqueductal gray (PAG)-evoked coordination of respiratory, laryngeal, and orofacial activity for vocalization have yet to be delineated. Two hypotheses have been offered. One theory is that this activity is mediated by a diffuse descending projection to parvocellular reticular interneurons, adjacent to the relevant laryngeal and orofacial motoneuronal pools. The second hypothesis is that the motor activity for vocalization is integrated via a projection from the PAG to a caudal medullary column of neurons, the nucleus retroambigualis (NRA). These hypotheses were tested with the use of a series of medullary transections combined with PAG stimulation. Transections that eliminated, in a series of caudal-to-rostral steps, the NRA, also eliminated the PAG-evoked cricothyroid and most of the thyroarytenoid laryngeal motor activity. These results indicate that the final common pathway for much of the laryngeal activity in PAG-evoked vocalization includes un initial synapse in the caudal medulla, presumably in the NRA. 2. The electromyographic changes evoked by microinjection of D,L-homocysteic acid (DLH) in the NRA of the unanesthetized, precollicular decerebrate cat were analyzed in order to delineate the NRA contribution to the coordinated respiratory, laryngeal, and oral muscle changes in vocalization. A total of 415 DLH injection sites were located at or caudal to the level of the obex. Vocalization was evoked at 46 of these sites, which were all confined to a restricted region of the ventrolateral medulla 1-3 mm caudal to the obex. This region corresponded to the rostral half of the NRA and the immediately adjacent medullary tegmentum. 3. In all experiments evidence was obtained that variable muscle activation, rather than functional and integrated muscle patterns, was represented within the NRA. Vocalization evoked by DLH microinjection in the NRA was usually associated with excitation of the cricothyroid, thyroarytenoid, external oblique, internal oblique, internal intercostal, and diaphragm muscles that occurred in a different manner from site to site. That is, injection at sites separated by 0.3-0.5 mm evoked quite different responses. 4. NRA-evoked vocalization was compared with PAG-evoked vocalization using small injections (1.5-4.5 nl) into each region. As well, larger microinjections (15-120 nl) into NRA were made for comparison with previous results from the PAG using similar doses. Within the PAG, stereotyped and relatively "fixed" patterns of muscle activity are represented, whereas within the NRA there was no representation of specific muscle patterns, but rather a partial topographic separation of "premotor neurons" regulating different muscles. Correspondingly, stereotyped vocalizations were never evoked from the NRA. Further, most NRA-evoked vocalizations were unusual in quality and would not be identified generally as feline. 5. Evidence was obtained for a separation of pathways from the PAG regulating sound production and orofacial modulation of that sound. In contrast to the results from the PAG, excitation of NRA neurons rarely evoked activity in the oral muscles (genioglossus or anterior belly of digastric) or orofacial modulation of sound production. 6. Our finding suggests that the NRA serves as an important substrate for the generation of respiratory pressure and larynges adduction, which are two essential aspects of not only vocalization but also several behaviors involving Valsava maneuvers such as coughing, vomiting, and defecation.

Effect of antiemetic therapy on recovery and hospital discharge time. A double-blind assessment of ondansetron, droperidol, and placebo in pediatric patients undergoing ambulatory surgery

BACKGROUND

Postoperative nausea and vomiting continue to be a significant problem for pediatric ambulatory surgery patients. Although ondansetron has been demonstrated to be effective in the prophylactic treatment of postoperative nausea and vomiting (surrogate end point) no one has demonstrated a benefit of antiemetic therapy on patient recovery, postanesthesia care unit length of stay, and hospital length of stay (nonsurrogate end points). In a double-blind manner, the effects of ondansetron, droperidol, and placebo on the incidence of emesis, postanesthesia care unit stay, and hospital discharge time were evaluated in children undergoing dental surgery.

METHODS

The subjects were 102 children aged 2-8 years undergoing complete dental restoration. All patients received midazolam before undergoing inhalation induction of anesthesia with N2O/O2 and halothane. Anesthesia was maintained with N2O/O2 and alfentanil. Patients were then randomized to receive ondansetron (0.1 mg/kg), droperidol (75 micrograms/kg), or placebo (normal saline) in a double-blind fashion. At the conclusion of the anesthesia, a trained nurse observer assessed patient recovery and recorded the time patients met specified criteria for postanesthesia care unit and hospital discharge as well as episodes of emesis in the hospital and at home during the first 24 hr after surgery.

RESULTS

Ninety-five patients completed the study. The three antiemetic groups were similar with respect to age, weight, length of surgery, dose of alfentanil, and route of preanesthetic medication. The 24-hr incidence of emesis was significantly less with ondansetron (9%) than with placebo (35%) or droperidol (32%). Ondansetron-treated patients had significantly shorter hospital stays than droperidol-treated patients, but recovery parameters were similar between the ondansetron- and placebo-treated patients.

CONCLUSIONS

Ondansetron is an effective prophylactic antiemetic agent for children undergoing dental surgery. Compared with droperidol, ondansetron decreases the length of hospital stay, but compared to placebo, there were no differences in the patient recovery parameters.

Abnormal cell proliferation and p52/p35-CSK expression in the colons of aging rats

In rodents and in humans, aging is associated with increased gastrointestinal epithelial cell proliferation and an expanded crypt proliferative compartment similar to that seen in the preneoplastic bowel. We have compared the distribution of a series of cytoskeletal antigens that are modified when colonic cancer cells differentiate in vitro in the colon of young (4-7 month) and aging (22-26 month) Fischer 344 rats. Two such proteins, p52 and p35, (that are increased in cultured senescent cells) differ in their position in the crypt axis and subcellular localization between young and aging rats. In young rats, immunoreactive p52 protein is present solely near the colonic crypt surface epithelium but in aging rats p52 expressing cells are found deeper in crypts. The intracellular localization of p35 also differs markedly in young and aging animals. The distribution of these proteins appears to be a reproducible biomarker of aging. Antigenic changes similar to those observed in aging colons also are seen in crypt cells of patients with ulcerative colitis and in the flat colonic mucosa of patients with adenomatous polyps and colon cancer. The combination of proliferative and differentiation changes suggest that the flat mucosa of the colon of aging rats has preneoplastic features.

Inositol phosphates modulate human red blood cell Ca(2+)-adenosine triphosphatase activity in vitro by a guanine nucleotide regulatory protein

D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] inhibits human red blood cell (RBC) Ca(2+)-stimulable, Mg(2+)-dependent adenosine triphosphatase (Ca(2+)-ATPase) activity in vitro. Because we have previously shown that adrenergic receptors exist on the human mature RBC membrane and can modulate Ca(2+)-ATPase activity, we examined the possibility that a guanine nucleotide regulatory protein (G protein) mediated the Ins(1,4,5)P3 effect. Guanosine 5'-O-(3-thiotrisphosphate) (GTP gamma S) 10(-4) mol/L also inhibited RBC Ca(2+)-ATPase activity. Pertussis toxin 200 ng/mL blocked the effects of both Ins(1,4,5)P3 and GTP gamma S on Ca(2+)-ATPase activity. In separate studies, pertussis toxin-catalyzed adenosine diphosphate (ADP) ribosylation was shown to occur in RBC membranes under conditions in which measurements of Ca(2+)-ATPase activity were performed. When Ins(1,4,5)P3 10(-7) mol/L and GTP gamma S 10(-6) mol/L were added to membranes concurrently, their inhibitory actions on the enzyme were additive. At greater concentrations of Ins(1,4,5)P3 (10(-6) to 10(-5) mol/L) and GTP gamma S (10(-4) mol/L), the inositol phosphate reversed the inhibitory effect of GTP gamma S. These observations indicate that the novel effect of Ins(1,4,5)P3 on the activity of a plasma membrane Ca(2+)-ATPase depends at least in part on the action of a pertussis toxin-susceptible G protein.

Structure-activity relationships of milrinone analogues determined in vitro in a rabbit heart membrane Ca(2+)-ATPase model

The cardiac activity of a series of analogues of the positive inotropic bipyridines amrinone (5-amino-[3,4'-bipyridin]-6(1H)-one) and milrinone (2-methyl-5-cyano-[3,4'-bipyridin]-6(1H)-one) was evaluated in vitro in a rabbit myocardial membrane Mg(2+)-dependent, Ca(2+)-stimulable adenosine triphosphatase (Ca(2+)-ATPase) model and structure-activity relationships were compared for nine closely related derivatives. In the present studies, a 5-bromo analogue of milrinone stimulated myocardial membrane Ca(2+)-ATPase significantly (10(-7) M; P < 0.001 vs control, with 67% of the activity of milrinone), whereas a 2'-methyl-2H-milrinone derivative was inactive. Although amrinone was inactive in this assay, its 2-methyl analogue was stimulatory. However, analogues lacking a 2-substituent (with or without a 5-cyano group) or with the 3-N position blocked by a methyl group did not stimulate myocardial membrane Ca(2+)-ATPase activity. Structural data for these bipyridines show that those with either a 2- or 2'-methyl substituent have a twist conformation, whereas those without are nearly planar. Activity data reveal that those bipyridines with a nonplanar conformation are more active in the Ca(2+)-ATPase assay. Further study of milrinone analogues with a 2'-methyl substituent shows that even though the effect on the twist angle is equivalent to that of 2-methyl substitution, these analogues are less potent. Data for this series reveal that the prerequisites for Ca(2+)-ATPase stimulation include not only a 2-methyl to maintain a twist conformation but also a free 3-N position and a 5-substituent. This model for optimal activity in the myocardial membrane Ca(2+)-ATPase system differs from those proposed for phosphodiesterase enzyme receptor recognition only in the requirement for a nonplanar molecule. We have previously shown that milrinone, but not amrinone, shares structural homology with thyroxine and was able to stimulate myocardial membrane Ca(2+)-ATPase activity in a manner similar to the thyroid hormone. Additionally, milrinone, but not amrinone, was an effective competitor for thyroxine binding to the serum transport protein transthyretin. Analysis of the milrinone-transthyretin crystal complex confirms the structural homology between milrinone and thyroid hormone which is not shared by amrinone. Modeling studies of the binding interactions of milrinone analogues indicate that the 2-desmethylmilrinone analogue, the most inhibitory analogue, lacks the hydrophobic contacts present in milrinone in its transthyretin-bound complex.(ABSTRACT TRUNCATED AT 400 WORDS)

Sequence and in vitro expression of the phosphoprotein gene of avian pneumovirus

The phosphoprotein (P) gene of two subgroup A strains of avian pneumovirus comprised 855 nucleotides containing only one substantial open reading frame encoding a protein of 278 amino acids, with a predicted M(r) of 30,323. In vitro translation of P mRNA in a wheat germ system resulted in the synthesis of two polypeptides of M(r) 35,000. Comparison of the deduced P protein sequence with that of the known mammalian pneumoviruses revealed overall amino acid identities ranging from 31 to 34.5%, suggesting a distant relationship. However, there was a much higher identity (63.2-68.4%) in a region of 57 residues, which included a heptad repeat sequence.

Breathing patterns during spontaneous speech

Lung volumes, speech intensity, the linguistic location of inspirations, and the variability of each, were studied during spontaneous speech in 6 healthy young women over 7 to 10 sessions each, using respiratory inductance plethysmography. Although average lung volume levels were within the vital capacity range previously reported for speech (Hixon, Goldman, & Mead, 1973), significant inter- and intrasubject variability was observed. This variability was considerable for some subjects (average initiation lung volume varying between 42 and 63% VC over the sessions) and relatively small for others (between 47 and 53% VC). Some of the lung volume variation was associated with changes in mood state, examined by self-report questionnaire at each measurement occasion. Linguistic factors were important influences in the lung volume variation. The majority of breaths in the conversations and monologues preceded structural (clause) boundaries. The volume of air inspired preutterance was found to be linked to the length of the ensuing breath group in each of our 6 subjects, as longer breath groups, spanning up to seven clauses in the spontaneous speech, were anticipated by inspiring to a higher lung volume. The subjects used a comfortable speaking intensity range, which varied for different individuals and sessions over 4 to 18 dB. Increases in speech intensity within individual ranges were not associated with increased lung volumes. The data provide novel insight into associations between physiological and linguistic factors in the control of speech breathing, and are suggestive of the existence of neural planning of the respiratory system, in anticipation of the demands of the utterance.

Treatment of mild hypertension with low once-daily doses of a sustained-release capsule formulation of verapamil

The efficacy and safety of a low dose (120 mg) of a sustained-release capsule formulation of verapamil administered once daily in the treatment of 42 patients with mild hypertension were assessed in this clinical trial. After a 4-week placebo washout period (baseline), patients with diastolic clinic blood pressures of 91 to 100 mm Hg inclusive were treated for 4 weeks with once-daily verapamil sustained-release 120 mg capsules. Clinic blood pressure was measured and 24-hour ambulatory blood pressure monitoring was performed at the end of both the baseline and the 4-week treatment periods. Twenty-four hour, day, and night systolic and diastolic ambulatory blood pressure were significantly (P < 0.01) reduced in the entire study population (24-hour, -5/-4 mm Hg; day, -6/-4 mm Hg; night, -4/-3 mm Hg). On the basis of mean daytime (6 AM to 6 PM) ambulatory diastolic blood pressure, patients were stratified into subgroups of patients with confirmed (> 85 mm Hg) and unconfirmed mild hypertension (< or = 85 mm Hg). The magnitude of the mean change in systolic and diastolic blood pressure was greater in the group of patients with confirmed mild hypertension than the group with unconfirmed hypertension. The incidence of adverse experiences was low in frequency and events were of mild severity; quality of life scores improved (P = 0.02). Low daily doses (120 mg) of verapamil sustained-release capsules provide a well-tolerated and sustained antihypertensive effect over 24 hours in patients with mild hypertension.

Coronary vasoconstriction mediated by endothelin-1 in neonates. Reversal by nitroglycerin

To determine the role of the vasoconstrictor peptide endothelin-1 in cardiopulmonary bypass in neonates, we measured plasma endothelin-1 concentrations in infants before and after cardiopulmonary bypass for arterial switch procedures and studied the effects of endothelin-1 on coronary tone and contractility in normal and reperfused neonatal pig hearts. Endothelin-1 blood concentrations (picograms per milliliter, mean +/- standard error) were significantly higher in neonates with arterial transposition and in umbilical venous blood (22.9 +/- 2.3 and 19.2 +/- 2.9, respectively) than in older children with atrial septal defects (13.2 +/- 1.6) or in healthy adults (10.7 +/- 2.5). After cardiopulmonary bypass, endothelin-1 concentrations increased 29% in neonates undergoing arterial switch procedure and 28% in children undergoing atrial septal defect repair (p < 0.05 versus before bypass). In isolated, blood-perfused neonatal pig hearts, endothelin-1 had dose-related coronary constrictor and inotropic effects between 25 and 100 pmol. Endothelin-1 concentrations that did not increase coronary perfusion pressure (5 to 10 pmol) caused significant coronary constriction in the presence of norepinephrine (10 nmol/L). During reperfusion after 30 minutes of global normothermic ischemia, the coronary vasoconstrictor effects of both endothelin-1 alone and endothelin-1 plus norepinephrine were significantly enhanced. Nitroglycerin reversed vasoconstriction produced by endothelin-1 and endothelin-1 plus norepinephrine both before and after ischemia-reperfusion. We conclude that endothelin-1 concentrations are significantly elevated in neonates and are further increased after cardiopulmonary bypass. Coronary vasoconstriction caused by endothelin-1 is enhanced by ischemia-reperfusion and by norepinephrine present in concentrations typically observed after neonatal cardiopulmonary bypass. Nitroglycerin reverses coronary vasoconstriction induced by endothelin-1 and may therefore be beneficial in the postoperative management of neonates after cardiac operations.

Preanesthetic medication with intranasal midazolam for brief pediatric surgical procedures. Effect on recovery and hospital discharge times

BACKGROUND

The perfect preanesthesia medication and its ideal route of administration are still debated, but for pediatric surgical patients undergoing brief procedures, preanesthesia medication is frequently omitted because of the concern that it will prolong the child's recovery from anesthesia. The effects of nasally administered midazolam on anesthetic recovery and hospital discharge times were determined in 88 ASA physical status 1 and 2 ambulatory surgical patients undergoing a brief surgical procedure.

METHODS

Using a randomized, double-blind, placebo-controlled design, 88 ambulatory surgical patients 10-36 months of age undergoing myringotomy and tube insertion were entered into the study. All patients were randomly assigned to one of three medication groups. One group received 0.2 mg/kg intranasal midazolam; a second group received 0.3 mg/kg intranasal midazolam; and the third group received intranasal saline drops. All patients were anesthetized with nitrous oxide, oxygen, and halothane administered via mask. The duration of anesthesia lasted between 9 and 10 min. After preanesthetic medication, the children were evaluated for ease of separation and induction of anesthesia. In addition, the time from when the anesthetic was discontinued until the child recovered from anesthesia and the time the child was discharged home were recorded by a nurse observer blinded to the patient grouping.

RESULTS

Children receiving midazolam had smoother, calmer parent-child separation and anesthesia induction scores, and their anesthesia recovery times and hospital discharge times were the same as those receiving placebo.

CONCLUSIONS

For children undergoing brief surgical procedures, nasal midazolam provides satisfactory anxiolysis without delaying anesthesia recovery and hospital discharge.

Clinical characteristics of sevoflurane in children. A comparison with halothane

BACKGROUND

For pediatric patients, sevoflurane may be an alternative to halothane, the anesthetic agent used most commonly for inhalational induction. The induction, maintenance, and emergence characteristics were studied in 120 unpremedicated children 1-12 yr of age randomly assigned to receive one of three anesthesia regimens: sevoflurane with oxygen (group S), sevoflurane with nitrous oxide and oxygen (group SN), or halothane with nitrous oxide and oxygen (group HN).

METHODS

Anesthetic was administered (via a Mapleson D, F or Bain circuit) beginning with face mask application in incremental doses to deliver maximum inspired concentrations of 4.5% halothane or 7% sevoflurane. End-tidal concentrations of anesthetic agents and vocal cord position were noted at the time of intubation. Elapsed time intervals from face mask application to loss of the eyelash reflex, intubation, surgical incision, and discontinuation of the anesthetic were measured. Heart rate, systolic, diastolic, and mean blood pressures, and end-tidal anesthetic concentrations were measured at fixed intervals. Anesthetic MAC-hour durations were calculated. The end-tidal concentration of anesthetic was adjusted to 1 MAC (0.9% halothane, 2.5% sevoflurane) for at least the last 10 min of surgery. Intervals from discontinuation of anesthetic to hip flexion or bucking, extubation, administration of first postoperative analgesic, and attaining discharge criteria from recovery room were measured. Venous blood was sampled at anesthetic induction, at the end of anesthesia, and 1, 4, 6, 12, and 18-24 h after discontinuation of the anesthetic for determination of plasma inorganic fluoride content.

RESULTS

Induction of anesthesia was satisfactory in groups SN and HN. Induction in group S was associated with a significantly greater incidence of excitement (35%) than in the other groups (5%), resulting in a longer time to intubation. The end-tidal minimum alveolar concentration multiple of potent inhalational anesthetic at the time of intubation was significantly greater in patients receiving halothane than in patients receiving sevoflurane. Induction time, vocal cord position at intubation, time to incision, duration of anesthesia, and MAC-hour duration were similar in the three groups. During emergence, the time to hip flexion was similar among the three groups, whereas the time to extubation, time to first analgesic, and time to attaining discharge criteria were significantly greater in group HN than in groups S and SN. Mean heart rate and systolic blood pressure decreased during induction in group HN but not in groups S and SN. The maximum serum fluoride concentration among all patients was 28 microM.

CONCLUSIONS

Sevoflurane with nitrous oxide provides satisfactory anesthetic induction and intubating conditions; however, induction using sevoflurane without nitrous oxide is associated with a high incidence of patient excitement and prolonged time to intubation. There were greater decreases in heart rate and systolic blood pressure during induction with halothane than with sevoflurane; however, these differences may be dose-related. The more rapid emergence with sevoflurane when compared with halothane is consistent with the low solubility of sevoflurane in blood and tissues. Children receiving sevoflurane for up to 9.6 MAC-hours did not develop high serum fluoride concentrations.