Search PubMed⌕ Search

Biomedical subjects

L Ho

Publications and source records attributed to L Ho.

At least 145 records · Page 8Linked to original sources
PubMed1985

Modulation by dexamethasone of the pyruvate dehydrogenase-complex activity in 3T3-L1 adipocytes.

Chronic exposure of 3T3-L1 pre-adipocytes to dexamethasone plus 3-isobutyl-1-methylxanthine (IBMX) with or without insulin caused a significant increase in the specific activity of 'total' pyruvate dehydrogenase complex (PDC) and in the percentage of the 'active' form of the complex compared with cells exposed to a chronic insulin treatment or an acute treatment (2 days) with dexamethasone plus IBMX. In acute-drug-switch-over experiments, dexamethasone also caused an increase in the percentage of 'active' PDC in 3T3-L1 adipocytes. The results show that, in 3T3-L1 adipocytes, dexamethasone, even in the absence of insulin, increases the proportion of PDC in its 'active' form. The mechanism of the dexamethasone effect remains to be investigated.

1-Methyl-3-isobutylxanthine↗
PubMed1984

Patterns of nutrient selection in rats with streptozotocin-induced diabetes.

The effects of experimental diabetes on energy intake, patterns of nutrient selection, water intake, body weight and body composition were examined in male Sprague-Dawley rats given ground Purina Chow or a dietary self-selection regime. Following adaptation to dietary conditions, a portion of the animals in each diet group were made diabetic by the administration of 45 mg/kg streptozotocin (STZ). The remaining animals in each group served as vehicle-injected controls. STZ reliably produced diabetes in rats on both dietary regimes. Immediately after the induction of diabetes, rats on the self-selection regime increased carbohydrate and protein intakes and decreased fat intake. Approximately three weeks after STZ administration, diabetic rats reduced carbohydrate intake and increased fat intake. Diabetic animals in both diet groups were hyperphagic and polydipsic relative to non-diabetic controls. During the first three weeks following STZ injections, energy and water intakes of diabetic animals in the two dietary conditions were similar. However, after this initial period, energy and water intakes of diabetic rats given the self-selection regime were significantly lower than those of diabetic animals given Purina Chow.

Animals↗
PubMed1984

Effect of TRH on plasma arginine vasopressin.

Effect of thyrotropic releasing hormone (TRH) on plasma arginine vasopressin (AVP) was studied in human subjects. All 7 normal controls and 2 hypothyrotropic hypothyroid subjects failed to show any rise of AVP on TRH administration. The 4 primary hypothyroid subjects had elevated basal AVP level and showed further elevation on TRH administration. Our data suggests that elevated TRH in primary hypothyroid subjects may act directly as a nonosmotic stimulus or modulate the osmoreceptor and hypothalamic neurohypophyseal system for AVP release.

Animals↗
PubMed1981

Sustained decrease in fat consumption produced by amphetamine in rats maintained on a dietary self-selection regime.

Total daily caloric intakes and dietary self-selection of the three macronutrients, protein, fat and carbohydrate, were examined in female rats following the administration of anorectic doses of d-amphetamine sulfate (0.5, 1.0 and 2.0 mg/kg body weight, IP). Animals had access to nutrients for a six-hour period each day with food intakes measured two hours after food presentation and again at the end of the six-hour feeding period. Amphetamine injections led to similar dose-related decreases in caloric intakes in animals maintained on a standard laboratory diet (ground Purina Laboratory Chow) and those maintained on the dietary self-selection regime. Detailed examination of feeding patterns of animals given the self-selection regime revealed, however, that amphetamine had differential effects on the consumption of protein, fat and carbohydrate. At all three drug doses, protein and carbohydrate intakes were suppressed during the initial two-hour measurement period. Intakes of these two macronutrients returned to control values by the end of the six-hour feeding period. In contrast, fat intake was initially suppressed and remained suppressed throughout the entire six-hour period following amphetamine administration. Comparison of the present results with those of previous experiments indicates that the selective effect of amphetamine on fat consumption is not a general effect of drugs which reduce caloric intake.

Animals↗
PubMed1979

Properties of (Mg2 + Ca2+)-ATPase of erythrocyte membranes prepared by different procedures: influence of Mg2+, Ca2+, ATP, and protein activator.

Erythrocyte membranes prepared by three different procedures showed (Mg2+ + Ca2+)-ATPase activities differing in specific activity and in affinity for Ca2+. The (Mg2+ + Ca2+)-ATPase activity of the three preparations was stimulated to different extents by a Ca2+-dependent protein activator isolated from hemolysates. The Ca2+ affinity of the two most active preparations was decreased as the ATP concentration in the assay medium was increased. Lowering the ATP concentration from 2 mM to 2-200 microM or lowering the Mg:ATP ratio to less than one shifted the (Mg2+ + Ca2+)-ATPase activity in stepwise hemolysis membranes from mixed "high" and "low" affinity to a single high Ca2+ affinity. Membranes from which soluble proteins were extracted by EDTA (0.1 mM) in low ionic strength, or membranes prepared by the EDTA (1-10 mM) procedure, did not undergo the shift in the Ca2+ affinity with changes in ATP and MgCl2 concentrations. The EDTA-wash membranes were only weakly activated by the protein activator. It is suggested that the differences in properties of the (Mg2+ + Ca2+)-ATPase prepared by these three procedures reflect differences determined in part by the degree of association of the membrane with a soluble protein activator and changes in the state of the enzyme to a less activatable form.

Adenosine Triphosphatases↗
PubMed1979

Orienting task specificity in incidental motor learning.

The manipulation of the retention of a linear movement by means of different orienting tasks in an incidental learning paradigm was investigated. Subjects were presented with a target position followed by a different nontarget position on each of four presentation trials. After the presentation trials subjects were required to recall the target and nontarget positions. One group made verbal estimates of the distance between the target and nontarget positions, another group discriminated between the target and nontarget positions, while no verbal responses were required for a third group. The verbal-response groups, while not differing from each other, had less error at recall than the nonverbalizing group. These findings were discussed in terms of the levels of processing framework for memory research (Craik & Lockhart, 1972).

Journal Article↗
PubMed1978

Levels of processing and the coding of position cues in motor short-term memory.

The present study investigated the appropriateness of the levels-of-processing framework of memory for explaining retention of information in motor short-term memory. Subjects were given labels descriptive of the positions to be remembered by the experimenter (EL), were given no labels (NL), or provided their own labels (SL). A control group (CONT) was required to count backwards during the presentation of the criterion positions. The inclusion of a 30-sec filled retention interval as well as 0-sec and 30-sec unfilled retention intervals tested a prediction by Craik and Lockhart (1972), when attention is diverted from an item, information will be lost at a rate appropriate to its level of processing - that is, slower rates for deeper levels. Groups EL and SL had greater accuracy at recall for all three retention intervals than groups CONT and NL. In addition, there was no significant increase in error between 30-sec unfilled and 30-sec filled intervals for groups EL and SL, while there was a significant increase in error for groups CONT and NL. The data were interpreted in terms of Craik and Lockhart's (1972) levels-of-processing approach to memory.

Journal Article↗
PubMed1978

Effects of relative frequency of knowledge of results on retention of a motor skill.

The effects of relative frequency of knowledge of results on the retention of a motor skill was studied. Adams' theory (1971) contends that the perceptual trace of a criterion position gains on increment of strenth each time the feedback stimuli associated with the criterion position are experienced and that it is the strength of the perceptual trace that determines retention. Schmidt's theory (1975), however, suggests that the recognition schema is updated only on trials on which the feedback stimuli associated with the criterion position are experienced in conjunction with knowledge of results and that it is the precision of the recognition schema that determines retention. Two experiments were conducted. The results provided evidence contrary to Adams' theory. Schmidt's theory, however, was only partially supported.

Humans↗
PubMed1976

Evaluation of a ghetto school breakfast program.

A program was initiated to provide a free breakfast at a ghetto elementary school. Community support was achieved at the expense of randomization of study subjects. While no significantly greater increase in school attendance or performance was detected in comparison with a control school, none of the students was malnourished and diets of students in the control school were as adequate as those in the breakfast school. Thus, it cannot be concluded that school breakfast programs would not benefit malnourished children or teen-agers who most often go without breakfast.

Black People↗
PubMed1975

SV40 induced polypeptides in infected and transformed cells.

5 structural (VP) and 3 non-structural (NSVP) SV40 induced polypeptides which display two kinetic patterns of synthesis are identified in infected cells. NSVP 1 and 2 are "early" functions of which only NSVP 1 is present in transformed cells; NSVP 3 is "late" function which is also present in a line (T-22) of transformed AGMK.

Cell Line↗