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S J Yaffe

Publications and source records attributed to S J Yaffe.

At least 19 recordsLinked to original sources
PubMed1994

Maternal and pediatric AIDS in the United States: the current situation and future research directions.

The epidemic of HIV infection and disease in women, adolescents and children represents a complexly intertwined biological and social challenge to health care workers and researchers alike. When considering various issues in confronting this epidemic, women must be viewed as individuals important in their own right, as the primary caretaker of their family members (both infected and uninfected), and as the sexual partners of men who may or may not be infected. Of the myriad of compelling biological questions facing AIDS researchers today, two of the most interesting involve the timing and determinants of vertical transmission and the natural history of HIV infection and disease in women. Scientifically, confronting this epidemic involves research into pathogenesis, epidemiology, natural history, treatment, and prevention of HIV infection. Primary emphasis in the research arena in HIV/AIDS in the United States is focused on therapeutic and prophylactic research. Other research issues are very important, including studies of early diagnostic techniques, behavioral research concerning reproductive choices, the role of breastfeeding in HIV transmission, HIV-specific adolescent issues, and surrogate markers of disease progression.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Paediatric labelling requirements. Implications for pharmacokinetic studies.

The US Food and Drug Administration (FDA) has proposed new labelling regulations that describe alternative approaches for providing additional information to support labelling a drug, already approved for use in adults, for use in children. Therefore, the study of drugs in paediatric populations may now be encouraged. Paediatric pharmacokinetic studies are an important part of these trials. This action by the FDA may help resolve the ethical and technological concerns about the performance of clinical trials in children, and may render paediatric clinical trials more feasible. Most investigations in children are opportunistic in nature and their design is often constrained by a requisite noninvasive approach. Appropriately applied population-based techniques for both pharmacokinetic and pharmacodynamic data analysis may represent the most robust approach for generating a sufficiently large and accurate database for the use of new or old drugs in paediatric patients. Accordingly, this information, which is crucial for paediatric labelling of any drug product, must be obtained in infants and children if we are to truly individualize therapy for paediatric patients. The funding of 6 Pediatric Pharmacology Research Units by the US National Institutes of Health, and guidelines for application of pharmacokinetic methods to children may further contribute to the performance of paediatric clinical trials.

Aging↗
PubMed1991

Critical periods of neuroendocrine development: effects of prenatal xenobiotics.

Phenobarbital, when administered prenatally in a small dose to animals, produced profound, and permanent effects on reproductive function in the offspring. Preliminary analysis of a unique cohort of adolescents who were exposed to phenobarbital in utero, suggests that long-term effects are also evident in the human. The precise nature of these effects is currently being determined and will be reported separately. These effects may be qualitatively and quantitatively different from effects seen in animals because of species difference in the timing or neuroendocrine differentiation. Of greater importance, however, is the fact that biologic and pharmacologic effects can be seen in the human following exposure to xenobiotics perinatally. Implications for other pharmacologic agents await further investigation. The rat model appears to have validity for extrapolation to man.

Animals↗
PubMed1990

Effects of prenatal treatment with phenobarbital.

Phenobarbital, when administered prenatally to animals, produced profound and prominent effects on reproduction. Preliminary analysis of a unique cohort of adolescents who were exposed to phenobarbital in utero suggests that long-term effects may be evident in the human as well.

Animals↗
PubMed1985

The effect of phenobarbital on theophylline disposition in children with asthma.

The disposition of theophylline was examined in seven children with asthma on two occasions before and on one occasion after chronic phenobarbital dosing (2 mg/kg/day). There was little intrapatient variability in apparent theophylline clearance between the two baseline assessments (0.081 versus 0.073 L/hr/kg). After 19 days of phenobarbital therapy, there was a significant increase in apparent theophylline clearance (0.104 versus 0.077 L/hr/kg), accompanied by a 30% decrease in the mean steady-state serum theophylline concentration (12.0 versus 8.4 micrograms/ml). The inducing effect of phenobarbital on theophylline metabolism may require theophylline dosage adjustment in patients with asthma who receive both drugs concurrently to maintain a given average steady-state theophylline concentration.

Asthma↗
PubMed1985

A study of adverse reaction algorithms in a drug surveillance program.

To improve agreement among observers, several investigators have recently proposed methods (algorithms) to standardize assessments of causality for presumed adverse drug reactions. We evaluated one such method in the context of an intensive pediatric drug surveillance program. Four observers rated 50 randomly selected case reports drawn from the program, first using only general guidelines and then, several months later, using the strict criteria of the algorithm. Agreement among observers was poor in both study phases. The presence of selected characteristics of adverse events (e.g., major severity) did not improve agreement in either phase of the study. We conclude that routine use of such algorithms in drug surveillance programs is not likely to be of benefit.

Child↗
PubMed1983

Tobramycin sulfate elimination in premature infants.

The elimination pharmacokinetics of tobramycin sulfate was studied in 25 newborn infants of birth weight 0.7 to 4.7 kg during 31 treatment episodes. The peak serum concentrations after a 2.5 mg/kg dose were usually within the therapeutic range of 5 to 10 micrograms/ml; however, the serum predose trough values were elevated above the theoretical safe limit of 2 micrograms/ml. Because of the prolonged serum elimination half-lives, a calculated extended dosage interval, sometimes greater than 24 hours, was necessary to obtain a predose trough of less than or equal to 2 micrograms/ml. The serum elimination half-lives inversely correlated with gestational age, extrauterine age, birth weight, and creatinine clearance. The very low ratio of tobramycin renal clearance to creatinine renal clearance was virtually constant and indicated a probable tubular reabsorption of tobramycin. A general dosage schedule based on birth weight was derived from the data. An alternative formula was derived to enable prediction of the tobramycin elimination half-life based on a combination of birth weight, gestational age, and extrauterine age for an infant younger than 7 days of age.

Anti-Bacterial Agents↗
PubMed1983

Environmental hazards in milk and infant nutrition.

Epidemiologic studies have provided much of the knowledge concerning adverse side effects of exposure to drugs and other xenobiotics transmitted via breast milk. Adverse effects can be immediate and usually recognizable or long-term and difficult to define. Acute effects may be due to individual idiosyncrasy, allergic reaction, or manifestation of acute toxicity. We need further human clinical investigations to determine actual dosing to nursing infants and to ascertain the existence of subtle and presently unrecognized long-term effects.

Animals↗
PubMed1983

Endotoxin and low protein diet induced depression of the rat hepatic drug metabolism.

The effects of the combination of low protein diet feeding and endotoxin (E. coli, serotype 026 B6) upon rat hepatic microsomal mixed function oxidase (MFO) enzymes were investigated. Short-term (7 days) feeding of low protein (8%) diet and acute (single dose) exposure to endotoxin resulted in an additive decrease in MFO enzymes. However, chronic (7 days) endotoxin exposure did not depress liver microsomal MFO enzyme activities except for aniline hydroxylase. Long-term (105 days) feeding of the low protein diet and acute endotoxin exposure further decreased aminopyrine N-demethylase and benzo(a)pyrene hydroxylase activities compared to individual treatments. These results suggest that, under these experimental conditions, the two host-related environmental factors interact and potentiate a decrease in rat hepatic microsomal drug metabolizing enzymes. These observations may be of clinical relevance to explain altered drug reactions in patients with gram-negative infections and endotoxemia under the conditions of malnutrition.

Animals↗
PubMed1983

Effect of protein depletion and intrauterine growth retardation on rat hepatic drug metabolism.

The effect of intrauterine malnutrition in rats on in vivo and in vitro drug metabolism at weaning was investigated. We have employed two experimental designs to produce intrauterine malnutrition, maternal dietary protein depletion starting at day 7 of gestation and unilateral ligation of the uterine artery on day 17 of gestation. At birth cross-fostering of newborns was done, experimental and control group of litters raised separately until weaning (21 days of age). Both methods produced offspring with lower body and liver weights and these changes were present at weaning. However, only in the protein-restricted group were significant differences for liver:body weight ratio and hepatic microsomal protein content observed. Liver microsomal cytochrome P-450 and b5 contents were significantly decreased in small animals from mothers with intrauterine vessels ligated but not in the prenatal protein-restricted group. A significant increase in aminopyrine N-demethylase and a decrease in aniline hydroxylase enzyme activities was observed in both experimental groups. No significant differences were found in reductive or conjugative pathways of drug metabolism. Hexobarbital sleeping time was significantly increased in weanling animals from the prenatal protein-restricted mothers but not in the uterine-vessels-ligated group. These results suggest that maternal malnutrition may play an important role in modulation of postnatal drug metabolism pattern of progeny.

Animals↗
PubMed1983

Influence of perinatal nutrition on hepatic drug metabolism in the adult rat.

Pregnant rats were fed high-fat (HF, 35% calories) or low-fat (LF, 5% calories) diet from 18 days of gestation to the end of the suckling period. Thereafter, male progeny were fed stock diet for 6 months, then sacrificed or challenged for 3 days with HF diet. There were no immediate posttreatment effects at 30 days of age on liver microsomal cytochrome P-450 or b5, aminopyrine (AP) N-demethylase or benzo(a)pyrene (BP) hydroxylase. At 7 months, cytochrome P-450 was lower in LF-fed than in HF-fed animals. High-fat challenge reduced cytochrome P-450 and cytochrome b5 content in both groups, AP N-demethylase only in LF animals and BP hydroxylase only in HF animals. These differential effects of perinatal exposure to diet on the later response of microsomal mixed-function oxidases to fat challenge suggest that early dietary experience may regulate the pattern of drug metabolism in adult life.

Aminopyrine N-Demethylase↗