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J Blanchard

Publications and source records attributed to J Blanchard.

At least 19 recordsLinked to original sources
PubMed1992

High-performance liquid chromatographic assay for the alpha-melanotropin[4,10] fragment analogue (Melanotan-II) in rat plasma.

A high-performance liquid chromatographic (HPLC) procedure has been developed for the quantification of Melanotan-II (MT-II), a cyclic heptapeptide which promotes rapid tanning of the skin, in rat plasma. The method involves precipitation of plasma proteins followed by direct-injection HPLC with ultraviolet detection. Calibration curves were linear over the range 100-1000 ng/ml for rat plasma. The method is reproducible and reliable with a detection limit of 50 ng/ml in plasma. Within- and between-day precision and accuracy reported as coefficient of variation and relative error, respectively, were < 7%. The application of the assay was successfully demonstrated by quantifying the concentration of MT-II in rat plasma samples following an intravenous dose of 0.3 mg/kg.

Amino Acid Sequence↗
PubMed1992

Methylxanthine levels in breast milk of lactating women of different ethnic and socioeconomic classes.

The purpose of this study was to evaluate the dietary caffeine and dimethylxanthine concentrations in breast milk of 40 mothers from different ethnic and socioeconomic backgrounds. Their diets and drug intake were not restricted in any way. Each nursing mother provided a fasting and a combined breast-milk sample each day for 3 consecutive days. No significant differences were found in intake levels of any of the methylxanthines among the groups tested. No significant differences were found among the four groups in breast-milk levels of caffeine, theobromine, or paraxanthine. However, the mean theophylline milk levels were significantly higher on 2 of the 3 days examined in Anglo-American woman compared to Hispanic-American women. Socioeconomic and ethnic variables were also compared among the four groups. The daily amounts of methylxanthines found in the breast milk of this free-living population of mothers do not appear to present clinically significant amounts to the infant.

Adult↗
PubMed1992

Quantitation of E. coli protein impurities in recombinant human interferon-gamma.

A multiple antigen ELISA for E. coli proteins (ECPs) that may be present in purified recombinant human interferon-gamma (rIFN-gamma) was developed. SDS-PAGE and Western blotting analyses showed that the assay antibodies reacted with a wide spectrum of ECPs in the standard and with ECPs in a production run. In spike recovery studies, rIFN-gamma at concentrations of 0.05 mg/mL and higher augmented the immunoreactivity of the ECPs in the standard curve (1.3-40.0 ng ECPs/mL) by approx 50%. To determine ECP content in purified rIFN-gamma, 0.2 mg/mL of rIFN-gamma was added to the standard curve diluent to compensate for enhanced immunoreactivity. The assay was precise (interassay precision of ECP controls < or = 4.1 %CV) and accurate with recoveries of 111-115% of expected for ECPs (15-40 ng/mL) spiked into purified rIFN-gamma (1 mg/mL). Linearity of dilution for ECPs spiked into rIFN-gamma was obtained (r = 0.999). Moreover, linearity of dilution was obtained for ECPs in "in-process" samples, demonstrating the required condition of antibody excess for this type of multiple antigen ELISA. ECPs were not detectable in several purified lots of rIFN-gamma. Therefore, these lots contained < 1.3 ppm ECPs.

Antibodies, Monoclonal↗
PubMed1992

Intergeniculate leaflet and suprachiasmatic nucleus organization and connections in the golden hamster.

The intergeniculate leaflet (IGL) is a distinct subdivision of the lateral geniculate complex which receives retinal input and projects upon a circadian pacemaker, the suprachiasmatic nucleus (SCN). In the present study, we have analyzed the organization of the IGL and its connections in the hamster, a species commonly used in circadian rhythm studies. The location of the IGL is defined by the presence of retinal afferents demonstrated by anterograde transport of cholera toxin-HRP, neuropeptide Y-containing neurons and axons, cells retrogradely labeled from the regions of the SCN and contralateral IGL, and substance P-containing axons. It is a long nucleus extending the entire rostrocaudal axis of the geniculate. The most rostral IGL lies between the lateral dorsal thalamus, ventrolateral part, and the horizontal cerebral fissure. It then enlarges ventral to the rostral dorsal lateral geniculate, medial to the optic tract. The mid-portion of the leaflet is a thin lamina intercalated between the dorsal and ventral geniculate nuclei. The extended caudal portion of the nucleus lies lateral and ventral to the medial geniculate and is contiguous with the zona incerta and the lateral terminal nucleus. The IGL contains populations of neuropeptide Y (NPY+) and enkephalin (ENK+) neurons which project to the retinorecipient portion of the SCN. In addition to the immunoreactive perikarya, the IGL contains plexuses of NPY+, ENK+, substance P-, serotonin-, and glutamic acid decarboxylase-immunoreactive axons. Retrograde transport studies demonstrate that, in addition to the NPY+ neurons, there is a population of non-NPY+ neurons projecting upon the SCN.(ABSTRACT TRUNCATED AT 250 WORDS)

Afferent Pathways↗
PubMed1992

Relationship between serum and saliva theophylline levels in patients with cystic fibrosis.

Theophylline levels in stimulated and unstimulated mixed saliva were compared with total and free (unbound) serum theophylline levels in 11 outpatients with cystic fibrosis (CF) who were using theophylline regularly. Stimulated saliva from CF patients predicted both total and unbound serum theophylline concentrations to within +/- 1 microgram/ml in 53.3 and 80.0%, respectively, of the samples examined. In addition, the total serum levels from CF patients could be used to predict unbound serum concentrations to within +/- 1 micrograms/ml in 100% of the cases examined. Furthermore, it was observed that prediction equations derived in a previous study with asthmatics employing identical methodology would allow both unbound and total serum theophylline levels to be predicted from saliva levels in CF patients with a degree of accuracy and precision that was approximately equal to or slightly better than the results obtained using prediction equations derived in other CF patients. These results indicate that saliva levels allow predictions of the unbound serum theophylline levels with greater accuracy and precision than they predict total serum theophylline levels. In addition, total serum levels can be used to reliably predict unbound serum levels. The use of mixed stimulated saliva is recommended as a reliable noninvasive method for monitoring unbound serum theophylline levels. The therapeutic range for saliva, which corresponds to the accepted total serum concentration range of 10-20 micrograms/ml, is approximately 5.55-11.3 micrograms/ml.

Adolescent↗
PubMed1992

Variability of the serum protein binding of theophylline in patients with asthma and cystic fibrosis.

1. The serum protein binding of theophylline was studied in 28 asthmatics and 11 patients with cystic fibrosis (CF) who were receiving the drug regularly. Peak theophylline samples were collected at 2 week intervals on four occasions in each asthmatic and on three occasions in each CF patient. The binding was measured using ultrafiltration at 37 degrees C and pH 7.4. The total and free (unbound) theophylline concentrations were measured using high-performance liquid chromatography. 2. The mean free-fractions (+/- s.d.) in asthmatics (0.50 +/- 0.03) and in CF patients (0.51 +/- 0.04) were not significantly different. The intra- and inter-subject variability in the free-fraction (fu) was relatively small in both patient groups. The binding was found to be concentration-independent at serum theophylline concentrations up to 30.9 micrograms ml-1. The effects of age, gender, serum albumin and total serum protein on the free fraction were evaluated. 3. The results indicate that the binding of theophylline is similar in the two disease states. The low degree of variability in serum theophylline binding indicates that measurements of total serum theophylline concentrations will reflect unbound serum concentrations with acceptable accuracy in both patient groups studied.

Adolescent↗
PubMed1992

Treatment with growth hormone-releasing hormone (GHRH) 1-44 in children with idiopathic growth hormone deficiency: a randomized double-blind dose-effect study. The GHRH European Multicenter Study (GEMS) Group.

One hundred and eleven pre-pubertal children (70 boys, 41 girls, aged 2.5 to 14.3 years) with growth failure (height 2 SD below the mean for chronological age (CA) and height velocity (HV) below the 10th percentile for bone age) due to idiopathic growth hormone deficiency (peak plasma GH < 20 mUI/1 to two standard provocative tests) were treated with GHRH 1-44 NH2. Patient stratification in two classes was performed according to body weight; in each class, patients were randomly allocated to one of seven GHRH doses, from 30 to 300 micrograms/day. GHRH was injected subcutaneously, every evening, for six months in a double-blind fashion. No relationship was found between the absolute or incremental HV during treatment and the dose (range from 1.3-23.1 micrograms/kg/day) of GHRH. However, HV (cm/year) increased from 3.8 +/- 0.1 (mean +/- SEM) before treatment to 6 +/- 0.2 during six months treatment and 47 patients (42%) increased their HV up to at least the mean normal HV for bone age (catch-up growth). Low titer antibodies to GHRH were found in 19 patients (17.1%) at six months; no adverse effect was observed. Our results suggest that patients showing catch-up growth were older, had a height closer to the mean for chronological age and a slower pre-treatment height velocity. Failure to demonstrate a relationship between GHRH dose and changes in growth velocity might be explained by the combination of a placebo effect, insufficient frequency of GHRH administration and heterogeneity of the population.

Adolescent↗
PubMed1992

What makes information important and its influence on learning in self-directed study.

This study investigated what makes text-based information important and what is its influence on learning. College students studied an expository text following their own self-directed study procedures. Data from Exp. 1 (n = 60) and Exp. 2 (n = 40) showed that information was considered important if it (a) began and ended text, (b) began a paragraph, (c) appeared at somewhat equal intervals in text, and (d) contained enumerations of concepts. Subjects recalled information that (a) began the text and (b) contained examples of enumerations. It appeared that text-based variables established what was important and this influenced learning. Implications for the selective attention hypothesis and its volume-of-attention corollary, the cycles hypothesis, and the slot-filling hypothesis are discussed.

Achievement↗
PubMed1992

Cross-training: a staffing alternative in ambulatory surgery.

Content plateauing, which occurs when one's work becomes too routine, may be prevented by the cross-training and cross-utilization of staff. This article tracks the process of cross-training and cross-utilization from its inception at Lutheran Medical Center in Denver, Colorado.

Ambulatory Surgical Procedures↗
PubMed1991

Depletion of brain serotonin by 5,7-DHT modifies hamster circadian rhythm response to light.

The midbrain raphe complex innervates the circadian rhythm regulating system by direct projections to the suprachiasmatic nucleus (SCN) and the intergeniculate leaflet (IGL). The present experiments examined the changes in circadian rhythm regulation consequent to the depletion of brain serotonin by central 5,7-dihydroxytryptamine (DHT) application. Adult male hamsters with access to running wheels were entrained to a light-dark cycle 14:10 (LD) of photoperiod, pre-treated with desmethylimipramine and given bilateral lateral ventricle infusions of 75 micrograms DHT/2.5 microliters 0.5% ascorbic acid in saline or vehicle only. Two separate experiments were performed. Four weeks after surgery, animals were transferred to either constant light (LL; Experiment 1) or constant dark (DD; Experiment 2). Animals remained in LL for 85 days, then were transferred to DD for 50 days, followed by a return to LD 14:10 for 14 days. Animals in Expt. 2 remained in DD for 55 days, were given 3 days food deprivation, then, beginning 35 days later, were periodically exposed to 30 min light pulses as a phase response curve (PRC) to light was generated. DHT treatment induced rapid appearance of advanced activity onset, delayed offset and longer duration of the nocturnal activity phase. DHT animals in LL had circadian locomotor rhythms much longer than control animals (24.43 +/- 0.04 vs 24.19 +/- 0.05 h) and normal circadian rhythmicity was rapidly lost by DHT animals in LL. There was no effect of DHT on circadian period in DD, but the DHT treated animals in DD had a larger phase delay region of the PRC than did controls and this was associated with an overall change in the temporal properties of the PRC. Serotonin immunohistochemistry showed an approximate 90% loss of cells from the dorsal raphe nucleus and decreased density of the serotonergic terminal field in the SCN and IGL. The results support the view that the serotonergic system modulates the phasic actions of light on the hamster circadian rhythm system. The data also indicate that hamsters can have a Type 0 PRC.

5,7-Dihydroxytryptamine↗
PubMed1991

Serotonergic modulation of the hamster wheelrunning rhythm: response to lighting conditions and food deprivation.

Depletion of brain serotonin by 5,7-dihydroxytryptamine (DHT) produces large changes in photic regulation of the hamster circadian running rhythm. This study documents the changes in daily wheelrunning caused by DHT lesions and their relationship to changes in photic conditions or food availability. Hamsters were given bilateral infusions of the selective neurotoxin during entrainment to a light-dark cycle (LD) of 14:10 h. At a later time, animals were transferred to constant light (LL) or dark (DD) for a prolonged period. Animals in DD were also subject to 3 days of food deprivation. Destruction of the serotonergic system does not change the amount of daily running in LD 14:10, but does alter the rate of running. Control animals respond to LL by greatly decreasing running compared to those with lesions. Food deprivation, a condition that greatly elevates running in control animals, is not nearly as effective in lesioned animals. The results suggest that serotonin-depleted hamsters have diminished responsiveness to environmental stimuli.

5,6-Dihydroxytryptamine↗
PubMed1991

Immunocytochemical characterization of the suprachiasmatic nucleus and the intergeniculate leaflet in the diurnal ground squirrel, Spermophilus lateralis.

The suprachiasmatic nucleus (SCN) and the intergeniculate leaflet (IGL) are retinorecipient structures that play important roles in the expression of circadian rhythmicity. We examined these two structures in a diurnal ground squirrel, Spermophilus lateralis, using immunohistochemical techniques, and cholera toxin-bound horseradish peroxidase. A number of immunoreactive substances are distributed within the ground squirrel SCN in a pattern similar to that reported in many other mammals. These include vasopressin, vasoactive intestinal polypeptide, serotonin, neuropeptide Y (NPY), and glial fibrillary acidic protein. The squirrel SCN differs from that of most other species examined to date in two respects. First, a dense cluster of cells containing immunoreactive L-enkephalin (L-ENK-IR) is observed in the center of the SCN. Second, there is a contralateral, but no ipsilateral, projection from the retina to the SCN. In the lateral geniculate region there is a substantial region that contains NPY-immunoreactive cells and receives a bilateral retinal projection. This region is assumed to be homologous with the IGL described in other mammals. Cells containing L-ENK-IR are distributed throughout the LGN in groups that overlap, but which have a distinctly different distribution than the more extensive groups of NPY-IR cells.

Animals↗
PubMed1991

Serum/saliva correlations for theophylline in asthmatics.

Theophylline levels in mixed saliva (both stimulated and unstimulated) were compared with total and free (unbound) serum theophylline levels in 28 asthmatic outpatients using theophylline regularly. Stimulated saliva predicted both total and unbound serum theophylline concentrations within +/- 1 microgram/mL in 62.5% and 92.9%, respectively, of the samples examined. In addition, the total serum levels could be used to predict unbound serum concentrations to within +/- 1 mg/L in 100% of the cases that were examined. These results indicate that saliva levels predict the unbound serum theophylline levels with greater accuracy and precision than they predict total serum theophylline levels. In addition, total serum levels can be used to reliably predict unbound serum levels. The use of mixed stimulated saliva is recommended as a reliable non-invasive method for monitoring unbound serum theophylline levels. The therapeutic range for saliva, which corresponds to the accepted total serum concentration range of 10-20 mg/L, is approximately 5.6-11.3 mg/L.

Administration, Oral↗
PubMed1991

Effects of gender on vitamin C pharmacokinetics in man.

The pharmacokinetics of vitamin C (VC) were compared in young and elderly male and female subjects following 500 mg oral doses to each subject in two states of VC nutriture: a depleted state achieved by 4-5 weeks on a diet containing less than 10 mg VC/day and a supplemented state which was achieved following 500 mg/day doses of VC for 3 weeks. The males were taller and heavier than their female counterparts and consequently had a greater body surface area (BSA). The body mass index (BMI) and fat mass did not differ between genders within an age group, whereas only the young females exhibited a greater percent body fat. The males exhibited a larger fat-free mass (FFM) than the females. None of the pharmacokinetic parameters differed due to gender in depleted subjects. In the supplemented state the female subjects exhibited a significantly greater peak VC concentration (Cmax), a longer absorption lag time (tlag), apparent volume of distribution (AVd) in L/kg, clearance (CL) in ml/hr/kg, and renal clearance (CLr) in ml/hr/kg. When AVd, CL, and CLr were expressed in absolute terms (i.e., L or ml/min), no gender-related differences were observed. A stepwise multiple linear regression indicated that Cmax was inversely linearly related to body weight, tlag was directly related to BSA and dose, and AVd (L/kg) was inversely linearly related to BSA. CL (ml/hr/kg) and CLr (ml/hr/kg) were not significantly related to any of the body composition parameters examined. Overall, these results indicate that there are few gender-related differences in the pharmacokinetics of VC in humans and that a portion of the observed differences can be explained by body composition differences between the sexes.

Adipose Tissue↗
PubMed1991

Depletion and repletion kinetics of vitamin C in humans.

Depletion and repletion profiles of vitamin C were determined in young and elderly males and females. Plasma vitamin C concentrations were determined upon entry into the study, once each week during a 5-wk period of dietary restriction (10 mg/day) of the vitamin and twice each week during a 2.5-wk period of supplementation with 500 mg/d. The rate constant (K) and the half-life of the depletion phase (t1/2) were determined. Other values calculated included the mean plasma vitamin C concentration in the four subject groups at entry, depleted and supplemented states of vitamin C nutriture. A t test indicated that none of the calculated values differed due to age. In contrast, K was significantly smaller in men, resulting in a longer t1/2. The entry and depleted plasma vitamin C concentrations did not differ due to gender whereas repleted plasma vitamin C concentrations were higher in women than in men. Data analysis indicated that plasma depletion of vitamin C is a first-order process. In addition, t1/2 was inversely related to entry vitamin C levels at concentrations below approximately 85 mumol/L whereas above this concentration t1/2 was approximately constant and averaged 14.2 d. This implies that a conservation effect may be operative at low plasma vitamin C concentrations.

Adult↗