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Biomedical subjects

R Gifford

Publications and source records attributed to R Gifford.

9 recordsLinked to original sources
PubMed1992

Long-term treatment with growth hormone of children with short stature and normal growth hormone secretion.

Children with short stature but normal growth rate and/or normal growth hormone response to sleep and secretagogues were treated with recombinant methionyl human growth hormone, 0.3 mg/kg per week. In each year of treatment, about 80% of the subjects maintained an increase in growth rate greater than the defined limit (greater than 1 cm/yr above pretreatment growth rate) for continuation of human growth hormone treatment. Comparison of the group that continued to respond to human growth hormone with the group that did not maintain an accelerated growth rate did not reveal differences in bone age delay, sleep or secretagogue-stimulated human growth hormone secretion, degree of short stature either absolute or relative to target height, and somatomedin C concentration before or after initiation of therapy. The group that failed to respond to the human growth hormone treatment in the first year of treatment was younger and had a higher pretreatment growth rate. Review of the longitudinal growth curves revealed five patterns of response to human growth hormone treatment: (1) failure to increase growth rate in two subjects with height SD scores within 1 SD of target height, (2) failure to increase growth rate in five subjects with height SD scores greater than 1 SD less than the target height, (3) acceleration in growth rate in three subjects that was not maintained until achievement of a height within 1 SD of the target height, (4) acceleration of growth rate in five subjects that was maintained until achievement of a height within 1 SD of the target height, and (5) acceleration in growth rate that was maintained during the 3 years of treatment in 15 subjects who had not attained a height within 1 SD of the target height. We conclude that human growth hormone treatment of some but not all short children with "normal" growth hormone secretion will result in sustained acceleration of growth rate and attainment of prepubertal heights that are closer to but do not exceed their genetic height potential. A clinical trial of human growth hormone may be necessary to determine which subjects will benefit from the treatment.

Age Determination by Skeleton↗
PubMed1987

Protein binding of glycopeptide antibiotics with diverse physical-chemical properties in mouse, rat, and human serum.

In previous studies of the pharmacokinetics and urinary excretion of nine glycopeptides with diverse isoelectric points (pI), as pI decreases, the total systemic and renal clearance, urinary recovery, and volume of distribution decrease, whereas the half-life increases. With glycopeptides of similar pI, clearance decreases and half-life increases with increasing lipophilicity. The present study examines the serum protein binding of these glycopeptide antibiotics in mouse, rat, and human serum and calculates the previously reported pharmacokinetic parameters for these drugs based on unbound concentration. Increased negative charge and lipophilicity increase serum protein binding (90-fold, fu 83% to 0.96%), which decreases the renal clearance and total systemic clearance (90-fold, 16.4 to 0.18 ml/min/kg) of these drugs. Increased serum protein binding also decreases the volume of distribution of these compounds, but this change is relatively small (sixfold, 755 to 131 ml/kg) compared with the change in total systemic clearance causing an increase in elimination half-life (25-fold, 20 to 492 min). The results demonstrate that the large differences in the total systemic clearance and half-life of these glycopeptide antibiotics are primarily due to dramatic differences in serum protein binding and not to differences in the intrinsic elimination processes (enzymes or transport proteins). It appears that the same physical-chemical properties that govern the protein binding and pharmacokinetics of small organic molecules govern the disposition of these high-molecular weight glycopeptide antibiotics.

Animals↗
PubMed1986

Analysis of epinine and its metabolites in man after oral administration of its pro-drug ibopamine using high-performance liquid chromatography with electrochemical detection.

Ibopamine (N-methyldopamine O,O'-diisobutyrol ester, hydrochloride) is an ester prodrug of epinine. Epinine is a cardiovascular agent used in congestive heart failure because of its dopaminergic and adrenoreceptor agonist properties. Quantitative analytical methods, using high-performance liquid chromatography coupled with electrochemical detection, were developed for the determination of epinine and its known metabolites in biological media. Epinine was extracted from human plasma and urine via an alumina adsorption procedure; this procedure was also used to estimate epinine conjugates after prior enzymatic hydrolysis. Penicillamine was added to the incubation mixture to inhibit isoquinoline production. Urinary dihydroxyphenylacetic acid levels were obtained using the same alumina adsorption procedure, while a separate analytical procedure utilizing a direct high-performance liquid chromatographic analysis of samples was developed for homovanillic acid and its conjugates. Coefficients of variation for all the assays were below 8%. These methods were used to study the pharmacokinetics and metabolic fate of epinine after oral administration of ibopamine to healthy volunteers.

3,4-Dihydroxyphenylacetic Acid↗
PubMedDate not supplied

Age, era, and life perspective: emotional connotations of the 1920's through the 1980's to individuals in their twenties through their eighties.

The affective meaning of seven decades (1920's to 1980's) to seven adult age groups (twenties to eighties) was examined. Measures of Pleasure, Excitement, Arousal, and Distress were obtained for each decade from each age group. The results showed, as one might expect, that decades vary in emotional character, but, more importantly, that the emotional character of individual decades sometimes differs significantly as a function of age. Older age groups view the century as more pleasurable and less distressing than do younger age groups. These variations in the emotional image of the twentieth century are discussed as one indicator of life perspective and as a possible source of intergenerational conflict.

Adult↗
PubMedDate not supplied

Substance misuse and the physical environment: the early action on a newly completed field.

Transactions between individuals and their physical settings involving consciousness-altering drugs are examined. Research has gradually expanded outward from the individual and the drug to include the social and, finally, the physical context of drug use and misuse. Similarly, theory has evolved from simple unidirectional causal tenets to complex multidirectional contextual tenets. Research to date is sparse and does not live up to the ambitious vision of current theoretical views, but some results are striking and provocative. The review is framed in terms of physical scale (macro-, meso-, and microenvironments) and specificity (from molecular features of a setting to molar environmental characteristics such as stimulation level). Three temporal phases are considered: the development, maintenance, and cessation of substance misuse. The paucity of empirical research combined with the potential importance of environmental factors means that many challenging questions remain for a new generation of researchers.

Humans↗