Cafeteria factors that influence milk-drinking behaviors of elementary school children: grounded theory approach.

This study was conducted to identify factors that influenced milk-drinking behaviors of elementary school children in North Texas. Ten focus groups with a total of 41 children aged 6 to 11 years were conducted using a grounded theory approach. Based on the principles of Social Learning Theory, milk preferences and health beliefs were identified as personal factors that influenced drinking. Cafeteria rules, milk flavor, product packaging, modeling by adults, and shared experiences were environmental factors. The data suggest that school cafeterias can capitalize on their unique position to offer milk-drinking opportunities that children can share to combine nutrition education with sensory experience.

Pharmacokinetics and pharmacodynamics of inhaled versus intravenous morphine in healthy volunteers.

BACKGROUND: A new pulmonary drug delivery system produces aerosols from disposable packets of medication. This study compared the pharmacokinetics and pharmacodynamics of morphine delivered by an AERx prototype with intravenous morphine. METHODS: Fifteen healthy volunteers were enrolled. Two subjects were administered four inhalations of 2.2 mg morphine each at 1-min intervals or 4.4 mg over 3 min by intravenous infusion. Thirteen subjects were given twice the above doses, i.e., eight inhalations or 8.8 mg intravenously over 7 min. Arterial blood sampling was performed every minute during administration and at 2, 5, 7, 10, 15, 20, 45, 60, 90, 120, 150, 180, and 240 min after administration. The effect of morphine was assessed by measuring pupil diameter and ventilatory response to a hypercapnic challenge. Pharmacokinetic and pharmacodynamic analyses were performed simultaneously using mixed-effect models. RESULTS: The pharmacokinetic data after intravenous administration were described by a three-exponent decay model preceded by a lag time. The pharmacokinetic model for administration by inhalation consisted of the three-exponent intravenous pharmacokinetic model preceded by a two-exponent absorption model. The authors found that, with administration by inhalation, the total bioavailability was 59%, of which 43% was absorbed almost instantaneously and 57% was absorbed with a half-life of 18 min. The median times to the half-maximal miotic effects of morphine were 10 and 5.5 min after inhalation and intravenous administration, respectively (P < 0.01). The pharmacodynamic parameter ke0 was approximately 0.003 min-1. CONCLUSIONS: The onset and duration of the effects of morphine are similar after intravenous administration or inhalation via this new pulmonary drug delivery system. Morphine bioavailability after such administration is 59% of the dose loaded into the dosage form.

Pediatric evaluation of the bispectral index (BIS) monitor and correlation of BIS with end-tidal sevoflurane concentration in infants and children.

UNLABELLED: The bispectral index (BIS) has been developed in adults and correlates well with clinical hypnotic effects of anesthetics. We investigated whether BIS reflects clinical markers of hypnosis and demonstrates agent dose-responsiveness in infants and children. In an observational arm of this study, BIS values in children undergoing general anesthesia were observed and compared with similar data collected previously in a study of adults. In a second arm of the study, a range of steady-state end-tidal concentrations of sevoflurane was administered and corresponding BIS documented. Data were examined for differences between infants (0-2 yr) and children (2-12 yr). No difference was seen in BIS values in children before induction, during maintenance, and on emergence compared with adult values. There was no difference in BIS between infants and children at similar clinical levels of anesthesia. In children and infants, BIS was inversely proportional to the end-tidal concentration of sevoflurane. The sevoflurane concentration for a BIS = 50 (95% confidence interval) was significantly different: 1. 55% (1.40-1.70) for infants versus 1.25% (1.12-1.37) for children. Although validation with specific behavioral end points was not possible, BIS correlated with clinical indicators of anesthesia in children as it did in adults: as depth of anesthesia increased, BIS diminished. BIS correlated with sevoflurane concentration in infants and children. The concentration-response difference between infants and children was consistent with data showing that minimum alveolar concentration is higher in children less than 1 yr of age. IMPLICATIONS: The use of bispectral index (BIS) during general anesthesia improves the titration of anesthetics in adults. The data from this study suggest that the same equipment and method of electroencephalogram analysis may be applied to infants and children.

Genetic consequences of a single-founder population bottleneck in Trifolium amoenum (Fabaceae).

We investigated the genetic consequences of a single-founder bottleneck in a population of showy Indian clover (Trifolium amoenum), a species presumed to be extinct until rediscovered near Occidental, California, in 1993. Electrophoretic variation was evaluated in the bottlenecked population and in a larger population (Dillon Beach) discovered during the course of this study, as well as in populations of two closely related species, T. albopurpureum var. dichotomum and T. macraei. We found a surprisingly high amount of polymorphism in the single-founder T. amoenum population from Occidental (15% of loci polymorphic; an average of 1.1 alleles per locus). However, this represents a 53% reduction in number of polymorphic loci and a 20% reduction in average number of alleles per locus compared to three Trifolium populations with putatively similar mating systems (the Dillon Beach T. amoenum population and both populations of T. albopurpureum var. dichotomum). Expanding the genetic base of the Occidental T. amoenum population is a priority due to concerns about loss of evolutionary potential and the possibility of deleterious effects associated with inbreeding. However, using seed from the Dillon Beach T. amoenum population may not be beneficial due to distinct, presumably adaptive differences between plants from the two populations and concerns about outbreeding depression.

A randomized, double-blind, dose-response study of ondansetron in the prevention of postoperative nausea and vomiting.

STUDY OBJECTIVE: To determine the dose-response relationship of ondansetron in preventing postoperative nausea and vomiting (PONV) in women undergoing elective surgery. DESIGN: Prospective, randomized, double-blind study. SETTING: University-affiliated hospital. PATIENTS: 175 women aged 18 to 80 years scheduled for elective surgery. INTERVENTIONS: One of six doses of ondansetron (0.5 mg, 1 mg, 2 mg, 4 mg, 8 mg, 16 mg) or placebo was given prior to the induction of general anesthesia with propofol. Maintenance was with nitrous oxide, isoflurane, opioid, and muscle relaxant. MEASUREMENTS AND MAIN RESULTS: The study period began when the patient emerged from anesthesia. Nausea scores were recorded on a 0 to 10 scale at multiple time points during the 24-hour study period. Patient satisfaction via a visual analog scale (VAS) was determined at 1 and 24 hours after awakening. Rescue medication was given for severe nausea, three emetic episodes within 15 minutes, or if requested by the patient. The primary efficacy variable was the need for rescue antiemetic therapy. The dose-response curve (by logistic regression) of the percentage of patients not rescued versus dose indicated an ED50 of 0.54 mg (95% confidence interval 0.03-1.05 mg). Fewer patients required rescue in the 4 mg dose group compared with lower doses. However, the difference reached significance only in comparison with the 0.5 mg dose group. Survival analysis of the need for rescue, and nausea score versus time curves, also both suggested the superiority of the 4 mg dose compared with lower doses. In addition, there was a highly significant correlation between the lack of need for rescue and satisfaction with anesthesia at 24 hours after emergence. CONCLUSION: The recommended dose of ondansetron for PONV prophylaxis in women remains 4 mg.

Bispectral analysis of the electroencephalogram predicts conscious processing of information during propofol sedation and hypnosis.

BACKGROUND: The bispectral index (BIS) measures changes in the interfrequency coupling of the electroencephalogram (EEG). The purposes of this study were (1) to determine whether BIS correlates with responses to command during sedation and hypnosis induced by propofol or propofol and nitrous oxide, and (2) to compare BIS to targeted and measured concentrations of propofol in predicting participants' responses to commands. METHODS: Twenty volunteers (15 men and 5 women, aged 22-50 yr) were given propofol by computer-controlled infusion, and EEG was recorded for off-line analysis of BIS. Responses to randomly ordered verbal commands or voice plus touch were measured with two categorical scales (CS1 and CS2, respectively). All subjects received a propofol infusion targeted to achieve effect site concentrations of 1, 2, 4, 2, 1, and 0 microg/ml. Ten participants had repeated infusion, whereas 10 others breathed 30% nitrous oxide and oxygen and received a propofol infusion targeted for 0.5, 1, 2, 4, 2, 1, 0.5, and 0 microg/ml. Five minutes after each targeted concentration had been reached, CS1, CS2, and arterial propofol concentration were determined. The area under the receiver operating characteristic curve was used to compare the accuracy of (1) BIS, (2) targeted propofol concentration, (3) measured concentration, and (4) treatment history as predictors of response. RESULTS: Bispectral index was a strong predictor of CS1 and CS2 (P < 0.0001) and significantly more accurate than targeted or measured propofol concentrations (P < 0.0003 and P < 0.003, respectively). It also provided additional predictive power when combined with treatment history (P < 0.02). Nitrous oxide slightly decreased the probability of response at a given value of BIS (P < 0.05), but accuracy was unaffected. CONCLUSIONS: Bispectral index accurately predicts response to verbal commands during sedation and hypnosis with propofol or propofol plus nitrous oxide. Accuracy is maintained in situations likely to be encountered during clinical use: when propofol concentrations are increasing or decreasing and when repeated measurements are made over time.

Pharmacokinetics and pharmacodynamics of remifentanil in persons with renal failure compared with healthy volunteers.

BACKGROUND: Remifentanil is an opioid analgesic for use in anesthesia. An ester linkage renders it susceptible to rapid metabolism by blood and tissue esterases. Thus it was hypothesized that remifentanil elimination would be independent of renal function. Because its principal metabolite (GR90291) is eliminated renally, it would depend on renal function. This study was designed to evaluate the pharmacokinetics and pharmacodynamics of remifentanil and its metabolite in persons with and without renal failure. METHODS: Two groups of volunteers received two-stage infusions of remifentanil: low dose with 0.0125 microg x kg(-1) x min(-1) for 1 h followed by 0.025 microg x kg(-1) x min(-1) for 3 h; and high dose with 0.025 microg x kg(-1) x min(-1) for 1 h followed by 0.05 microg x kg(-1) x min(-1) for 3 h. Blood samples were collected for analysis of remifentanil and GR90291 concentrations. The pharmacokinetics of remifentanil were fit using a one-compartment pharmacokinetic model. Remifentanil's effect was determined intermittently using minute ventilation during a hypercapnic (7.5% CO2) challenge. RESULTS: Fifteen patients with renal failure and eight control participants were enrolled. The clearance and volume of distribution of remifentanil were not different between those with renal failure and the controls. Patients with renal failure showed a marked reduction in the elimination of GR90291; the half-life of the metabolite increased from 1.5 h in the controls to more than 26 h in patients with renal failure. The steady-state concentration of GR90291 is likely to be more than 25 times higher in persons with renal failure. There were no obvious differences in opioid effects on minute ventilation in the controls and in patients with renal failure. CONCLUSIONS: The pharmacokinetics and pharmacodynamics of remifentanil were not altered in patients with renal disease, but the elimination of its principal metabolite, GR90291, was markedly reduced. Based on simulations, the concentration of GR90291 at the end of a 12-h remifentanil infusion of 2 microg x kg(-1) x min(-1) is not likely to produce significant opioid effects.

Should relatives be allowed in the resuscitation room?

This article explores some of the reasons why the presence of relatives in the resuscitation room is not common practice, and presents some of the advantages and perceived disadvantages of allowing relatives entry. The author also examines the attitudes of A&E staff from studies undertaken on this topic and finally looks at some of the recommendations made for the implementation of this practice.

Acute multiple sclerosis (Marburg type) is associated with developmentally immature myelin basic protein.

We have studied a case of acute, fulminating multiple sclerosis (MS) (Marburg type) at the pathological and biochemical levels. Postmortem examination of the brain revealed extensive areas of gross rarefaction in the hemispheric white matter. Histologically, well-demarcated areas of demyelination with a large influx of macrophages and a subtle perivascular infiltration of lymphocytes were seen with relative preservation of the axis cylinders. Myelin basic protein (MBP) was isolated and purified [correction of purifed] from noninvolved white matter. It was slightly larger in molecular weight than MBP from normal brain or from chronic MS brain. The increase in mass was accounted for, in part, by the deimination of 18 of 19 arginyl residues to citrulline, making the patient's MBP much less cationic than MBP from normal white matter. When expressed as the ratio of least cationic form of MBP to the most cationic (C-8/C-1), the normal ratio was 0.82, chronic MS 2.5, and the patient in this study 6.7. Because the ratio of 6.7 was similar to 7.5 found for a 15-month-old infant, MBP was considered to be of the immature form. The data are consistent with a genetic factor influencing the charge microheterogeneity of MBP. The resulting less cationic MBP cannot carry out its normal function of compacting multilayers.

Pharmacokinetics and pharmacodynamics of remifentanil in volunteer subjects with severe liver disease.

BACKGROUND: Remifentanil, a new mu-opioid agonist with an extremely short duration of action, is metabolized by circulating and tissue esterases; therefore, its clearance should be relatively unaffected by changes in hepatic or renal function. This study was designed to determine whether severe hepatic disease affects the pharmacokinetics or pharmacodynamics of remifentanil. METHODS: Ten volunteers with chronic, stable, severe hepatic disease and awaiting liver transplantation and ten matched controls were enrolled. Each subject was given a 4-h infusion of remifentanil. The first five pairs received 0.0125 microgram x kg(-1) x min(-1) for 1 h followed by 0.025 microgram x kg(-1) x min(-1) for 3 h; the second five pairs received double these infusion rates. During and after the infusion, arterial blood was obtained for pharmacokinetic analyses, and the ventilatory response to a hypercarbic challenge was assessed. Simultaneous pharmacokinetic and pharmacodynamic analyses were performed. The pharmacokinetics were described using a one-compartment intravenous infusion model, and ventilatory depression was modelled using the inhibitory E(max) model. The pharmacokinetics of the metabolite GR90291 were determined using noncompartmental methods. RESULTS: There were no differences in any of the pharmacokinetic parameters for remifentanil or GR90291 between the two groups. The subjects with liver disease were more sensitive to the ventilatory depressant effects of remifentanil. The EC(50) values (the remifentanil concentrations determined from simultaneous pharmacokinetic/pharmacodynamic analyses to depress carbon dioxide-stimulated minute ventilation by 50%) in the control and hepatic disease groups were 2.52 ng/ml (95% confidence interval 2.07-2.97 ng/ml) and 1.56 ng/ml (95% confidence interval 1.37-1.76 ng/ml), respectively. CONCLUSIONS: The pharmacokinetics of remifentanil and GR90291 are unchanged in persons with severe, chronic liver disease. Such patients may be more sensitive to the ventilatory depressant effects of remifentanil, a finding of uncertain clinical significance, considering the extremely short duration of action of the drug.

Initial clinical experience with remifentanil, a new opioid metabolized by esterases.

Remifentanil is a new, esterase-metabolized opioid for anesthesia. Nonspecific esterases terminate the drug effect, with a context-sensitive half-time which plateaus at 3-4 min. This dose-ranging pilot study was designed to estimate the dose requirement of remifentanil for abolition of the responses to skin incision and intraoperative stimuli, and to determine the speed of recovery. Fifty-one unpremedicated patients took part at two centers. Anesthesia was induced with propofol, 67% nitrous oxide, and vecuronium. Remifentanil was then given (1 microgram/kg, plus an infusion of 0.0125-1.0 micrograms.kg-1.min-1). Responses were defined as: > 15% increase in systolic blood pressure or > 20% increase in heart rate, tearing, sweating, movement, or coughing. Responses to incision or surgery were treated with 0.5 micrograms/kg remifentanil boluses and a 50% increase in infusion rate, which could be done twice. Subsequent responses were treated with propofol or isoflurane. Remifentanil and nitrous oxide administration were terminated after the incision was closed. ED50 for response to skin incision varied between the two study sites (0.020 and 0.087 microgram.kg-1.min-1). ED50 for response to all surgical stimuli was 0.52 microgram.kg-1.min-1. At 0.3 microgram.kg-1.min-1 or more, only 3 of 21 patients required isoflurane. Recovery was not longer in patients receiving larger doses to spontaneous ventilation (2.5-4.6 min), tracheal extubation (4.2-7.0 min), and response to verbal command (3.0-4.6 min). Postoperative pain was reported in most patients (92%) at a median time of 21 min. We conclude that remifentanil was effective and well tolerated as a component of nitrous oxide-opioid-relaxant anesthesia.(ABSTRACT TRUNCATED AT 250 WORDS)

Endoscopic ligation of esophageal varices in children.

Seven consecutive patients presenting acutely with suspected variceal hemorrhage underwent endoscopic variceal ligation (EVL) of esophageal varices. Active bleeding had ceased by the time of the initial EVL session in all patients, although active variceal hemorrhage was controlled by EVL in one patient during a subsequent episode of bleeding. Treatment sessions were repeated at approximately monthly intervals until varices were reduced in size to grade 1 (< 4 mm diameter) or eradicated. All patients had portal hypertension secondary to intrahepatic disease. Patient age ranged from 2.4 to 14.5 years (mean, 8.5 years). One patient underwent successful liver transplantation 1 week after the initial treatment session. The remaining six patients required a mean (+/- SD) of 4.0 +/- 1.3 treatment sessions for elimination of varices. One episode of recurrent variceal hemorrhage and one episode of treatment-related hemorrhage occurred in two separate patients. Transient, mild dysphagia or odynophagia occurred in all patients. No other complications were reported during a mean (+/- SD) follow-up period of 13.8 +/- 4.6 months (range, 8-20 months). Recurrent varices were seen in three of four (75%) patients returning for follow-up endoscopy between 5 and 8 months from initial eradication. All underwent repeat EVL without complication. Endoscopic variceal ligation may be a suitable substitute for sclerotherapy in children with bleeding esophageal varices.

High mortality, fluctuation in numbers, and heavy subterranean insect herbivory in bush lupine, Lupinus arboreus.

Sporadic patchy die-off of bush lupine, Lupinus arboreus, has long been known. We describe in detail a series of these incidents on the central California coast, based upon observational and comparative evidence. Stands of thousands of plants die, while nearby mature plants live on. In some sites, repeated die-off followed by regeneration from the seed bank has led to the cover and density of this woody, perennial plant fluctuating widely over the 40 year period for which records exist. Root damage by caterpillars of the ghost moth or "swift" Hepialus californicus (Lepidoptera, Hepialidae) is a major cause of individual bush death and a probable cause of die-off of stands of lupine. Hidden from view underground, a few of these insects readily kill a juvenile or young mature plant by girdling and reaming-out roots. The mass mortality of L. arboreus that we observed involved heavy root damage by these caterpillars in evenaged stands of plants in their first (1.5-year-old) or second (2.5-year-old) flowering season. The injured plants set seed before dying. Older, larger bush lupines better withstood root damage. In plants aged 3 or more years, damage and mortality were correlated with the intensity of ghost moth caterpillars in the roots. At the highest intensity (mean = 37.5, maximum = 62 caterpillars/root), a stand of large, old L. arboreus suffered 41% mortality; 45% of root cambium (median value) was destroyed by feeding caterpillars. Mass death of mature L. arboreus was not correlated with folivory, and leaf damage ranged from nil to moderate in instances of die-off. The western tussock moth, Orgyia vetusta, accounted for the highest levels of folivory, but this insect was rare when die-offs occurred. The lowest lupine mortality rates in our study occurred where tussock caterpillar intensities were high and where plants were repeatedly defoliated by this insect. However, experimental defoliation by high, but realistic, intensities of tussock moth caterpillars resulted in some mortality of mature bushes, and the combined effects of leaf and root herbivory have yet to be assessed. In its natural range on the California coast, bush lupine has several additional species of insect herbivores that can be locally abundant and injurious to the plant, although none is associated with die-off. Subterranean natural enemies of ghost moth caterpillars may play a role in the patchy waxing and waning of this shrub. Locally, a new species of entomophagous nematode (Heterorhabditis sp.) cause high mortality in the soil, before ghost moth caterpillars have entered the root. This natural enemy may thus afford lupines protection from heavy underground herbivory.

The role of endoscopy in inflammatory bowel disease.

Endoscopy has assumed a preeminent role in the diagnostic approach to IBD. It is more sensitive than radiography in detecting early, subtle changes of IBD, both through endoscopic appearance and histologic sampling of mucosa. Endoscopy also appears to be a safe technique in patients presenting with severe forms of colitis and can play an important role in defining the etiologic basis of disease in this subgroup of patients. In addition to its diagnostic role, endoscopy has proven useful in surveying disease activity, through the development of endoscopic disease activity indices. Endoscopy has also found a prominent role in the diagnostic and therapeutic approach to IBD complications. Endoscopic surveillance of chronic UC patients at risk for colon carcinoma has helped to define a therapeutic approach to this serious complication of UC. Endoscopic therapy has been applied to treat stricture formation associated with long-standing CD. Biliary endoscopy also represents the strategy of choice for diagnosing primary sclerosing cholangitis, an extraintestinal complication occurring in 5% of UC patients. Finally, endoscopy may help facilitate the discovery of disease pathogenesis in IBD, through the use of endoscopically recovered biopsy specimens in the research laboratory. Endoscopy allows for ready access to human tissue that has been the cornerstone of disease-related research over the past two decades.

The role of upper gastrointestinal endoscopy in foreign body removal.

Upper gastrointestinal foreign bodies can be difficult to manage. Patient population, consultant expertise, and equipment availability play an important role in the decision to use rigid versus flexible endoscopes or radiologic methods. The various foreign bodies, clinical signs and symptoms, and treatment approaches are reviewed in this article.

Management of bile leaks following laparoscopic cholecystectomy.

In a series of 650 consecutive laparoscopic cholecystectomies, nine bile leaks were identified (1.4%). Patients with bile leaks presented clinically at a mean of 4.9 days (range: 3-8 days) after surgery complaining of diffuse abdominal pain, ileus, and nausea. Laboratory values for complete blood counts and liver function tests were all mildly elevated. Definitive diagnosis was made on the basis of abnormal hepatobiliary scintigraphy. Management strategies included laparotomy and drain placement (n = 1), laparoscopy and drain placement (n = 3), ERCP and drainage (n = 4), and CT-guided percutaneous drainage (n = 1). When the etiology of the leakage was identified, it was most commonly either dysfunction of the cystic duct clips (n = 3) or leakage from a disrupted duct of Luschka (n = 2). The source of the remaining leaks (n = 4) was never determined. We conclude that bile leaks are an uncommon cause of morbidity following laparoscopic cholecystectomy. Diagnosis can usually be made with nuclear medicine biliary tract scans and a variety of managements alternatives are successful in treating this complication.

Failure of piezoelectric lithotripsy of a gallstone impacted in the gallbladder neck.

Failure of extracorporeal shockwave lithotripsy is most frequently related to total stone mass, the size of individual stones, or unrecognized stone calcification which interferes with the dissolution effects of orally administered bile salts. We report a case of piezoelectric extracorporeal shockwave lithotripsy failure in a young woman with a 2-cm stone impacted in the neck of the gallbladder. Despite adequate positioning of the shockwave focal point on two separate occasions, no fragmentation was achieved. The stone was subsequently retrieved after the woman underwent laparoscopic cholecystectomy. When treated ex vivo, the stone rapidly fragmented. We hypothesize that the impacted stone, lacking a uniform liquid interface, failed to fragment because of the inability of cavitational forces to achieve a surface effect.

Bacteremia after endoscopic band ligation of esophageal varices.

In a 6-month period, 17 consecutive unselected patients undergoing emergency or elective endoscopic variceal band ligation were evaluated prospectively for clinical and bacteriological signs of bacteremia after each treatment session. None had signs of sepsis, fever, or chills; however, in one patient, a coagulase-negative Staphylococcus epidermidis was cultured from peripheral blood at 5 but not 30 min after the procedure. These data indicate that, in contrast to sclerotherapy, endoscopic variceal ligation rarely induces bacteremia.

Endoscopic band ligation for treatment of non-variceal upper gastrointestinal bleeding.

An endoscopic band ligation method was successful in achieving hemostasis in two patients who had severe coagulopathy and profuse gastrointestinal bleeding from a visible vessel in the stomach. Bleeding was not controlled by multiple epinephrine injections or BICAP electrocoagulation. The technique of band ligation was easy to perform and may provide an alternative treatment for non-variceal upper gastrointestinal bleeding in selected cases.