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Biomedical subjects

S Palmer

Publications and source records attributed to S Palmer.

14 recordsLinked to original sources
PubMed1992

Role of the adenylate cyclase, phosphoinositidase C and receptor tyrosyl kinase systems in the control of hepatocyte proliferation by hepatocyte growth factor.

Hepatocyte growth factor (HGF) is the most potent known mitogen for hepatocytes in primary culture. However, the mechanisms through which HGF induces hepatocyte proliferation have not been defined. Here we have investigated the role of the adenylate cyclase, phosphoinositidase C and tyrosine kinase signalling systems in the control of hepatocyte proliferation by HGF using freshly isolated or cultured adult rat hepatocytes. We show that human recombinant HGF caused a dose-dependent increase in hepatocyte DNA synthesis with a maximal effect at 10 ng/mL and an EC50 of 5.9 ng/mL. HGF had no effect on hepatocyte adenylate cyclase activity or intracellular cAMP levels. Elevation of hepatocyte cAMP levels resulted in inhibition of HGF-stimulated DNA synthesis. HGF stimulated inositol phospholipid hydrolysis with a maximal effect at 25 ng/mL and potentiated the effect of vasopressin (10(-8) and 10(-9)M). HGF (100 ng/mL) caused an increase in the phosphorylation on tyrosine of an unknown hepatocyte protein with a molecular mass of 36 kDa. Thus, we have shown that HGF, like epidermal growth factor (EGF), can activate the phosphoinositidase C and tyrosine kinase systems in rat hepatocytes. As with EGF, these intracellular signalling systems may underlie HGF-induced hepatocyte proliferation.

Adenylyl Cyclases↗
PubMed1992

Grouping based on phenomenal similarity of achromatic color.

It is widely acknowledged that a precondition for the perception of the world of objects and events is an early process of organization, and it has generally been assumed that such organization is based on the Gestalt laws of grouping. However, the stage at which such grouping occurs, whether early or late, is an empirical question. It is demonstrated in two experiments that grouping by similarity of neutral color is based not on similarity of absolute luminance at the level of the proximal stimulus, but on phenomenal similarity of lightness resulting from the achievement of lightness constancy. An alternative explanation of such grouping based on the equivalence of luminance ratios between elements and background is ruled out by appropriate control conditions.

Adult↗
PubMed1979

The immature monkey as a model for studies of bronchopulmonary dysplasia.

The monkey is a potential model for BPD since there is considerable background information on the normal-developing lung, the prematurely delivered infant is viable, HMD can be produced, the infant is large enough to permit physiologic measurements, and it should be possible to test the effects of positive pressure, oxygen, and pharmacologic agents. Clearly further information is needed on the cellular and subcellular changes occurring during the acute and recovery stages of HMD. The monkey has already proven to be of value in this inquiry. Studies on mechanisms of altered lung repair by various injurious agents are needed, and will require an animal model as well as in vitro systems. Basic understanding of the pathogenesis of bronchopulmonary dysplasia with establishment of the relative importance of the contributing factors should help in our efforts to prevent or minimize chronic lung disease in the newborn infant.

Animals↗
PubMed1979

Lung development in the fetal primate Macaca nemestrina. III. HMD.

Delivery of M. nemestrina at 80% of normal gestation provides a population of neonates at high risk for hyaline membrane disease (HMD). The diagnosis of HMD was made by the presence of reticulogranular densities and air bronchograms on chest radiographs. Patchy atelectasis was seen in the lungs of animals assigned by clinical and radiographic criteria to the HMD group and not in the normal lungs of animals matched for gestational and postnatal age. Total phospholipid and phosphatidylcholine in whole lung, airway lavage fluid, and surface-active materials were lower in animals with HMD. Amniotic fluid L/S ratios were lower in the group that developed HMD. Pressure-volume measurements indicated decreased distensibility and unstable terminal air spaces in the HMD group. Alveolar-arterial oxygen pressure differences were greater in animals with HMD. There were no differences between HMD and normal groups in body weight, lung weight, percent dry lung weight, gestational age, and postnatal age at death. This primate species, subjected to premature delivery, is a suitable animal model of HMD in human neonates.

Amniotic Fluid↗
PubMed1977

Single-subject design and interaction analysis in the behavioral treatment of a child with a feeding problem.

A research paradigm, including an AB1AB2 single-subject design was developed and used in conjunction with an adult-child interaction analysis methodology to evaluate the effectiveness of a behavioral treatment approach to a feeding problem in a 2 1/2-year-old male. The results indicate that after nine treatment sessions, the child's diet was appropriate and the undesirable mother-child interaction pattern was changed. In addition, the interaction analysis methodology was used to evaluate the therapist's behavior modification techniques so that these could be taught to the mother. This study continued the previous endeavors to delineate feeding problems in children and subsequently to treat these problems with a behavioral approach. This kind of systematic research, with functional analysis of presenting problems and specification of the therapist's treatment behavior, is offered as a clinically appropriate paradigm for psychotherapy and behavior modification research.

Behavior Therapy↗
PubMed1976

A model interdisciplinary diagnostic and treatment nursery.

A model interdisciplinary diagnostic and treatment nursery program for developmentally disabled children is objectively described to enable documentation of effectiveness and replication. The major components of the program were the parent-professional partnership and the objective specification by the interdisciplinary team of problems, treatment plan, and treatment methods for each youngster. The concept of efficiency index is used to document and compare program effectiveness for four treatment cases, one of which is presented in detail. Reasons for program effectiveness and potential problem areas are discussed.

Child↗
PubMed1976

Nutrition: an integral component in the health care of children. The interdisciplinary team in action.

The purpose of this paper is not to disseminate new findings or to review past research, but simply to state a progressive clinical philosophy in practical terms. Current emphasis on specialization and the simultaneous need for comprehensive health care seriously challenge the health professional's ability to provide adequate services without a well integrated interdisciplinary approach. In addition, clinical experience strongly points toward the need for individualization of treatment within this broad spectrum of interdisciplinary management. The problems of childhood allergies, epilepsy, and feeding problems are used to illustrate this concept, and the interplay between psychic and somatic factors has been highlighted as rationale for integration of nutrition in an interdisciplinary health care program for children.

Child↗
PubMed1975

Applied behavior analysis in the treatment of childhood feeding problems.

This paper discusses behavioral mismanagement as a cause of feeding problems in children and reports the case of a six-year-old handicapped boy who was subsisting almost entirely on pureed foods at the time of his referral. Treatment with applied behavior analysis resulted in his acceptance of food normal for his age, and at follow-up 12 months after treatment the variety of foods eaten and the nutrient intake were virtually normal for his age. The authors discuss the frequent occurrence of feeding problems in children and their possible causes. They propose that such problems constitute a clinical entity and suggest a preliminary classification system for them.

Behavior Therapy↗