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Measurement of alcohol and tobacco availability to underage students.

Communities Mobilizing for Change on Alcohol (CMCA) and Tobacco Policy Options for Prevention (TPOP) are randomized multicommunity trials designed to reduce the availability of alcohol (CMCA) and tobacco (TPOP) products to underage youth. We assessed the test-retest reliability and internal consistency of perceived availability measures developed for surveys of middle and high school students. Two questionnaires were administered twice, each to separate student populations (CMCA: 9th graders; TPOP; 8th graders) 21 to 26 days apart. A total of 111 (CMCA) and 70 (TPOP) subjects participated at both times (participation rate of 93.3% and 84.3%, respectively). There were no statistically significant differences in the distribution of demographic variables, alcohol or tobacco use variables, or availability variables across administrations. The scales assessing perceived access to alcohol or tobacco had high internal consistency (Cronbach's alpha of 0.84 for alcohol and 0.77 for tobacco), but moderate to low test-retest correlations (0.58 and 0.13, respectively). Single-item measures of sources of alcohol and tobacco and reported buy attempts also had moderate to low test-retest correlates (0.10-0.65). We recommend that items assessing tobacco and alcohol availability to underage youth be further developed.

Adolescent↗

PubMed1990

The effects of different iodide availabilities on thyroid function during development in Japanese quail.

Japanese quail (Coturnix japonica) were used to study the effects of different egg iodide (I) availabilities on thyroid function during development. Low (less than 50 micrograms 1/kg feed in the maternal diet) and high (1200 micrograms 1/kg feed) I availability were compared to control levels (800 micrograms 1/kg feed), a standard supplementation for game bird feed. We measured thyroid gland content of I, triiodothyronine (T3) and thyroxine (T4), plasma concentrations of T3 and T4, hepatic 5' monodeiodinase (5'-D) activity, and the response of the thyroid gland to thyrotrophin (TSH) stimulation. Embryos, on day 14 of the 16.5-17 day incubation period, and 1-day chicks were used for most studies but thyroid gland hormone content and plasma hormone concentrations were determined for more stages. With high I, thyroidal I content was elevated but thyroidal T4 and T3 were not different from controls. Plasma T3 and T4, the thyroid gland response to TSH stimulation, and hepatic 5'-D activity did not differ between control and high I. Reduced body weight occurred with high I. In general, thyroid gland weight was not altered, but some high I birds exhibited thyroid hypertrophy and altered thyroid gland function. With low I availability, thyroid gland contents of I and T4 were reduced but thyroidal T3 content was maintained. The thyroid gland response to TSH stimulation, plasma thyroid hormone concentrations, and the developmental patterns of plasma thyroid hormones, hepatic 5'-D activity, body weight and thyroid weight were not different between control and low I groups. Developing Japanese quail exhibit excellent ability to adjust thyroid function over a wide range of I availabilities. Regulation appears to occur at the level of thyroid hormone synthesis in the thyroid gland, which allows most aspects of thyroid dynamics to remain unchanged in the maintenance of circulating thyroid hormone concentrations.

Animals↗

PubMed1996

Lower serum L-tryptophan availability in depression as a marker of a more generalized disorder in protein metabolism.

Recently, it has been reported that major and melancholic depression are accompanied by a lower availability of total L-tryptophan (L-TRP) to the brain and by significant changes in electrophoretically separated protein fractions, such as albumin and alpha 2-globulin. The aim of this study was to examine the relationships between serum L-TRP availability and total serum protein, albumin, and alpha 2-globulin in 42 depressed and 24 normal subjects. In depressed and normal subjects, alone and together, there were significant and positive correlations between serum L-TRP and total serum protein or albumin concentrations. In the depressed subjects, but not in normal controls, there were significant inverse relationships between the L-TRP/competing amino acid ratio and the alpha 2-globulin fraction. Serum L-TRP and albumin were significantly lower in melancholic subjects than in normal and minor depressed subjects. Depressed subjects had a significantly lower L-TRP/competing amino acid ratio and significantly higher serum alpha 2-globulin than normal controls. Total serum protein was significantly lower in major depressed subjects than in normal controls. The results suggest that lower L-TRP availability to the brain in depression is related to lower serum albumin and to increased alpha 2-globulin fraction, which are both hallmarks of the acute phase response in depression. the results further corroborate the hypothesis that lowered L-TRP availability in depression is related to the acute phase response in that illness.

Analysis of Variance↗

PubMed2006

Availability of nutrition information from chain restaurants in the United States.

BACKGROUND: Although obesity and poor dietary habits are complex multifactorial problems, away-from-home food has been identified as one likely and important contributor. Restaurants provide a growing and substantial portion of the average American's diet, yet the Nutrition Labeling and Education Act (NLEA), which went into effect in 1994, explicitly exempts restaurants from most labeling requirements. Thus, this study examined the availability of nutrition information from the largest chain restaurants in the United States. METHODS: Between January and August 2004, we surveyed the 300 largest chain restaurants by telephone, e-mail, or examining company websites (response rate was 96%). The top chains, as ranked by revenue, were selected based on 2002 ratings in Restaurants and Institutions. RESULTS: Fifty-four percent of the 287 largest chain restaurants made some nutrition information available. Forty-four percent had nutrition information for the majority of their standard menu items. We found no significant differences in the availability of nutrition information based on the size of the restaurant chain. Of those restaurants with nutrition information, 86% provided information on the company website. CONCLUSIONS: The number of restaurants providing nutrition information has increased over the last 10 years. However, making informed and healthful food choices is hampered by the absence of nutrition information at many restaurants. Given the growing and significant role that away-from-home foods play in Americans' diets, the Surgeon General and the National Academies' Institute of Medicine recommend that nutrition information be available to customers at restaurants, and state legislatures and the U.S. Congress are beginning to address the issue.

Food Labeling↗

PubMed2005

Nonprescription availability of emergency contraception in the United States: current status, controversies, and impact on emergency medicine practice.

In October 2004, the American College of Emergency Physicians Council joined more than 60 other health professional organizations in supporting the nonprescription availability of emergency contraception. This article reviews the history, efficacy, and safety of emergency contraception; the efforts toward making emergency contraception available without a prescription in the United States; the arguments for and against nonprescription availability of emergency contraception; and the potential impact nonprescription availability could have on the practice of emergency medicine in the United States.

Adolescent↗

PubMed2006

Buprenorphine duration of action: mu-opioid receptor availability and pharmacokinetic and behavioral indices.

BACKGROUND: Buprenorphine (BUP) is effective in the treatment of opioid dependence when given on alternating days, probably as a result of long-lasting occupation of micro opioid receptors (microORs). This study examined the duration of action of BUP at microORs and correlations with pharmacokinetic and pharmacodynamic outcomes in 10 heroin-dependent volunteers. METHODS: Availability of microOR (measured with positron emission tomography and [(11)C]-carfentanil), plasma BUP concentration, opioid withdrawal symptoms, and blockade of hydromorphone (HYD; heroin-like agonist) effects were measured at 4, 28, 52, and 76 hours after omitting the 16 mg/d dose of BUP in a study reported elsewhere. RESULTS: Relative to heroin-dependent volunteers maintained on BUP placebo, whole-brain microOR availability was 30%, 54%, 67%, and 82% at 4, 28, 52, and 76 hours after BUP. Regions of interest showed similar effects. Plasma concentrations of BUP were time dependent, as were withdrawal symptoms, carbon dioxide sensitivity and extent of HYD blockade. Availability of microOR was also correlated with BUP plasma concentration, withdrawal symptoms, and HYD blockade. CONCLUSIONS: Together with our previous findings, it appears that microOR availability predicts changes in pharmacokinetic and pharmacodynamic measures and that about 50%-60% BUP occupancy is required for adequate withdrawal symptom suppression (in the absence of other opioids) and HYD blockade.

Adult↗

PubMed2026

Availability and public reimbursement of early breast cancer care across European expert centres: a PORTRAIT from an EUSOMA initiative.

BACKGROUND: Cross-country disparities in access to guideline-recommended early breast cancer care persist across Europe. PORTRAIT is a clinician-reported, cross-sectional access study mapping availability and state reimbursement of key services across the early breast cancer pathway. METHODS: A 49-item survey covering diagnostics, pathology and genomics, systemic therapy, surgery, radiotherapy, and supportive care was emailed from June to September 2024 to multidisciplinary teams at one expert breast centre in 42 European countries. Respondents provided a consensus perspective on service availability and reimbursement. Descriptive proportions with full, partial, or no access were calculated. RESULTS: Thirty-nine countries responded (93%). Core diagnostics were widely available, but gaps persisted: MRI-guided biopsy was absent in 29% of countries and vacuum-assisted biopsy was fully reimbursed in 66%. Genomic assays were unavailable in 14% and not fully reimbursed in 35%. Public funding gaps were reported for PARP inhibitors (33%) and CDK4/6 inhibitors (26%). Immediate implant-based reconstruction and biological meshes lacked reimbursement in 21% and 33%, respectively. Despite broad availability of hypofractionated radiotherapy, 38% of countries still used per-fraction reimbursement. Psycho-oncology was limited in 35%, fertility preservation in 46%, and patient-reported outcome measures absent in 43%. CONCLUSION: Basic services are nearly universal, but gaps persist in advanced imaging, molecular testing, targeted therapies, radiotherapy reimbursement, reconstructive/oncoplastic surgery, and survivorship care. PORTRAIT identifies practical targets for policy audit, reimbursement alignment, and resource stewardship. Findings reflect clinician perspectives from expert centres, potentially representing best specialist care rather than average national care, and are not population-representative estimates or direct measures of patient outcomes.

Humans↗

PubMed2006

Metal availability and uptake by sorghum plants grown in soils amended with sludge from different treatments.

Several factors depending on the sludge, the soil, or the combination of both substrates, may affect element availability to plants. In this study, an assessment was done of the effect of two sludges obtained by different processes (activated sludge and facultative stabilization pond) on heavy-metal availability and uptake by sorghum plants in soils with high and low copper contents. Results obtained for DTPA-extractable metal indicated higher metal availability in sludge-amended soils. In addition, sludges caused changes in copper and zinc distribution in soil, indicating in most cases a discrete increase in the more labile metal forms. However, observed changes did not increase heavy metal concentration in plant leaves, indicating that assessment of metal availability by a chemical procedure (single extraction or metal fractionation) would not permit a good prediction of metal bioavailability. On the other hand, sludge application at a rate of 100 t ha(-1) to high-copper agricultural soils would not imply greater mobility of this metal on account of a greater sorbing capacity provided by the sludges. Such results would indicate that sludges from wastewater treatment plants, meeting the standards of heavy metal contents, regardless of the process by which they were obtained, may be applied to several kinds of soil, even to high-copper soils, with no risk of increasing heavy metal bioavailability to phytotoxic levels in the short range.

Biomass↗

PubMed2005

A positron emission tomography (PET) investigation of the role of striatal dopamine (D2) receptor availability in spatial cognition.

The functional significance of age-related changes in regional brain dopamine (DA) function is poorly understood in health. Two recent studies have reported positive linear associations between measures of striatal DA (D2) receptor availability (binding potential) and specific aspects of motor and cognitive performance, after controlling for the effects of age [(Volkow, N.D., Gur, R.C., Wang, G.-J., Fowler, J.S., Moberg, P.J., Ding, Y.-S., Hitzemann, R., Smith, G., Logan, J., 1998. Association between decline in brain dopamine activity with age and cognitive and motor impairment in healthy individuals. Am. J. Psychiatry 155 (3), 344-349; Backman, L., Ginovart, N., Dixon, R.A., Wahlin, T.-B.R., Wahlin, A., Halldin, C., Farde, L., 2000. Age-related cognitive deficits mediated by changes in the striatal dopamine system. Am. J. Psychiatry 157 (4), 635-637)]. We investigated the relationship between measures of striatal DA (D2) receptor availability and visuo-spatial cognitive performance in thirty healthy post-menopausal women aged 58-90 years. [(11)C] Raclopride (RAC) positron emission tomography (PET) was used to assess dopamine (D2) receptor availability. The CANTAB neuropsychological test battery was used to assess spatial span, spatial working memory (SWM) and planning ability. Age showed significant linear correlations with several of the CANTAB performance measures. After controlling for age effects, DA (D2) receptor measures in left-sided striatal regions (caudate and putamen) were significantly and positively correlated with 'perfect solution' scores--the measure of performance accuracy--on the Tower of London (TOL) test of spatial planning. When this relationship was examined in relation to task difficulty, only perfect scores for the most 'difficult' (4-move) problems were significantly correlated with BP measures in all striatal regions, most notably the right and left caudate nuclei. Paradoxically, individuals with higher DA (D2) receptor measures in the right caudate performed less accurately on the SWM task, exhibiting a higher number of errors within each search sequence. The relative contribution of striatal DA (D2) receptor availability to specific aspects of cognitive performance needs to be evaluated in larger mixed-sex samples to facilitate the meaningful investigation of the potential therapeutic benefits of DA (D2) agonists in later life.

Aged↗

PubMed2004

Cue reactivity in smokers: the effects of perceived cigarette availability and gender.

We examined the effects of perceived cigarette availability and gender on smoking cue reactivity. Smokers were exposed to smoking cues (smoking paraphernalia) and control cues whilst their subjective and physiological responses were measured. Perceived cigarette availability was manipulated on a between-subjects basis before cue exposure. Relative to control cues, smoking cues evoked increases in the level of skin conductance in all participants. Cigarette craving was also increased in the presence of smoking cues, but only in female participants. Perceived cigarette availability had no effect on these responses. Participants also showed salivary reactivity to smoking cues, with males showing a decrease in salivation, and females showing an increase, but only when cigarettes were perceived as unavailable. These results suggest that perceived cigarette availability may not influence craving and skin conductance reactivity to smoking cues in minimally dependent smokers who are not nicotine deprived. In addition, the present data suggest that there are important gender differences in craving reactivity to smoking cues.

Adult↗

PubMed2006

The availability and use of oxygen saturation monitoring in primary care in order to assess asthma severity.

INTRODUCTION: The BTS/SIGN guideline recommends oxygen saturation (SaO2) monitoring as an objective measure of acute asthma severity, particularly in children, in both primary and secondary care. We assessed the availability and use of SaO2 monitoring for acute asthma assessment in primary care. METHODS: Fax and telephone questionnaire of Primary Care services in the Edinburgh region to assess use of SaO2 monitoring in the past 24 months, in association with a 24-month retrospective assessment of A&E attendances with acute wheeze. Children over 12 months of age registered with eligible general practices attending A&E with wheeze and/or asthma were included. RESULTS: There were replies from 103 general practices (100%) and eight Out-of-hours cooperatives (100%). Oxygen saturation monitoring was available in four general practices (3.9%) and three Out-of-hours cooperatives (37.5%). 1408 children attended A&E with wheeze/asthma, 721 referred by primary care. Oxygen saturation monitoring was available to 7.9% of A&E attendees from primary care, but documented in only 1.8% of primary care referrals. CONCLUSIONS: SaO2 monitoring is not widely available in primary care and is infrequently used for the assessment of acute asthma. SaO2 measurement as an adjunct to clinical assessment of asthma in primary care needs encouragement.

Adolescent↗

PubMed2005

Decreased brain tryptophan availability as a partial determinant of post-partum blues.

BACKGROUND: The post-partum blues is a transient mood alteration affecting most women a few days after delivery. Its stereotypic pattern of symptoms and time course, peaking on post-partum day 3-5, is suggestive of biological determinants superimposed on psycho-social factors. This study was designed to evaluate the possible role of the serotonin system during this period through assessment of brain tryptophan availability. METHODS: Blood samples from 50 women were collected just before (D0) and 3 days after (D3) delivery. Based on plasma concentration of tryptophan, amino acids competing with tryptophan for transport across the blood-brain barrier and on their respective affinities for this transporter, a brain tryptophan availability index (BTAI) was calculated and its variation correlated with the intensity of post-partum blues evaluated through the Kennerley and Gath score at D3. RESULTS: The BTAI showed a -15% decrease between D0 and D3 (p < 0.01, paired t-test). This decrease was not supported by a drop in plasma tryptophan since its level rather increased (+19%). There was no evidence for change in placental indoleamine-2,3-dioxygenase activity since the variation in plasma l-kynurenine (+12%) paralleled the change in tryptophan level. The decreased BTAI appeared the consequence of a dramatic increase in plasma levels of most amino acids, particularly the competitor aminoacids leucine, isoleucine, valine and tyrosine, during the early post-partum. This decrease in brain tryptophan availability was concomitant to the post-partum blues, whose intensity significantly correlated with the amplitude of BTAI variation (Pearson's coefficient -0.283, p < 0.05). CONCLUSION: This study suggests that generalized, large amplitude metabolic and/or nutritional changes occurring in the early post-partum result in a transient decrease in brain tryptophan availability, partly accounting for the mood alteration referred to as the post-partum blues, a model for the triggering of puerperal mood disorder in vulnerable women.

Adult↗

PubMed2004

Emergency drug availability on general paediatric units.

Following an incident where intravenous lorazepam was not available on a general paediatric ward we undertook a national survey of emergency drug availability on general paediatric units in the United Kingdom. Drugs chosen were those recommended in the Advanced Paediatric Life Support manual and the British National Formulary for the management of the most common paediatric emergencies. Twelve drugs were chosen covering emergencies in the following systems: cardiovascular (adrenaline (epinephrine), atropine and adenosine); neurological (flumazenil, lorazepam, paraldehyde, phenytoin and mannitol); metabolic (Hypostop Gel and glucagon); analgesia related (naloxone); and respiratory (aminophylline). A thirteenth drug, intravenous salbutamol was included in a reminder letter sent to non-responding units. Questionnaires were sent to 274 units. Replies were received from 242 (88.3%), of whom 20 did not have a general paediatric ward, leaving 222 units (81.0%). Drug availability varied for the different drugs: adrenaline (available on 100% of units), atropine (98.2%), naloxone (96.4%), phenytoin (95.9%), aminophylline (93.2%), paraldehyde (92.3%), mannitol (87.8%), lorazepam (86.9%), glucagon (86.5%), Hypostop Gel (80.6%), adenosine (72.1%) and flumazenil (66.7%). Six of the drugs were classified as first line agents (adrenaline, atropine, adenosine, lorazepam, paraldehyde and aminophylline). Over one in 10 units did not stock two or more of these first line drugs. Consideration needs to be given to the compiling of a consensus based list of drugs that ought to be stocked on all general paediatric units.

Cardiopulmonary Resuscitation↗

PubMed2005

Temporal trends of total and potentially available element concentrations in sewage biosolids: a comparison of biosolid surveys conducted 18 years apart.

The application of biosolids to agricultural land is becoming increasingly popular because of the many benefits they can offer in terms of improved soil fertility and productivity, and also because land application offers an economically viable disposal option. However, the heavy metal and nutrient content of biosolids are potential causes for concern due to the possibility of their accumulation in soils to levels that may adversely affect the environment. Therefore, total concentrations of elements in biosolids and the fraction potentially available to organisms must be known in order to accurately gauge the risks and to classify the biosolids. In 1983, deVries conducted a survey to determine the total and available contents of elements in biosolids collected from various treatment plants around Australia. We conducted a similar survey on biosolids collected in 2001, and thus were able to identify temporal trends in biosolid characteristics. The 2001 survey included biosolids from several treatment plants sampled in 1983, thus some direct comparisons were possible, and in four cases, it was possible to examine temporal trends in biosolid characteristics within individual treatment plants. Total element concentrations were determined by aqua regia digestion, and available element concentrations were determined by 0.01 M CaCl(2) extraction. Results showed total concentrations of Cu, Mn, Ni, Na, and Ca changed little over the period examined, however the 2001 median values of Cd, Mg, Pb, and Zn were all reduced by 60% or greater. Median total concentration of K was more than 50% higher, and P 120% higher, in the 2001 survey. Changes in the availability of elements surveyed in 1983 and 2001 were varied for different elements and for different biosolids. Extractable element concentrations (viewed as percentages of total concentrations) of Cu, Cd, and Ni all fell by 50-72% between 1983 and 2001, while K extractability fell by 35%.

Agriculture↗

PubMed2004

Regulation of thyroid hormone availability in liver and brain by glucocorticoids.

Glucocorticoids as well as thyroid hormones are essential for normal brain development. Exogenous glucocorticoids stimulate 3,3',5-triiodothyronine (T(3)) availability in circulation of birds and similar effects have been observed in sheep. Chicken data indicate that glucocorticoid administration also stimulates thyroid hormone metabolism in brain but the effects on local thyroid hormone concentrations are not known. Therefore, the current study: (1) determined local thyroid hormone availability in separate brain areas of 18-day-old embryonic chickens (E18) after injection of dexamethasone (DEX), and (2) investigated the impact on the thyroid hormone metabolic pathways in these brain parts and compared the results with the hepatic situation. For this, E18 chicken embryos were treated with a single intravenous dose of DEX (25 microg). Despite the decreased 3,5,3',5-tetraiodothyronine (T(4)) availability in the liver of the DEX treated embryos, the T(3) content was strongly increased, parallel to the plasma T(3) surge. This T(3) surge was primarily related to a fall in hepatic T(3) breakdown through a downregulation of the type III deiodinase (D3). The sulfation pathway in liver seems not to be affected by DEX. In all brain parts, DEX affects the T(3) production capacity by upregulation of the type II deiodinase (D2). This enables the brain to compensate for the decrease in T(4) availability, although the T(3) concentrations are not consistently increased like in plasma and liver. This observation points to the existence of a fine-tuning mechanism in brain that enables the brain to keep the T(3) concentrations within narrow limits.

Animals↗

PubMed1998

Variation in the mineral content of commercially available bottled waters: implications for health and disease.

PURPOSE: Although the annual consumption of bottled water in North America is 12.7 gallons per capita, little is known about the potential health effects of these waters. We reviewed the amounts of major minerals found in commercially available bottled waters, the recommended daily allowances for these minerals, and their beneficial and harmful effects. METHODS: We obtained the mineral content of various commercially available bottled waters in North America and Europe from The Pocket Guide to Bottled Water. We then conducted a Medline search to identify articles examining the beneficial and harmful effects of magnesium, sodium, and calcium. RESULTS: Great variation exists in the mineral content of commercially available bottled waters. Among the bottled waters that we reviewed, the magnesium content ranges from 0 to 126 mg per liter, the sodium content ranges from 0 to 1,200 mg per liter, and the calcium content ranges from 0 to 546 mg per liter. Epidemiologic and clinical studies suggest that magnesium may reduce the frequency of sudden death, that sodium contributes to the occurrence of hypertension, and that calcium may help prevent osteoporosis. CONCLUSION: The ideal bottled water should be rich in magnesium and calcium and have a low sodium content. Because there is great variation in the mineral content of commercially available bottled waters, the actual mineral content of bottled water should be considered when selecting one for consumption.

Calcium↗

PubMed1992

Steady-state availability of sodium channels. Interactions between activation and slow inactivation.

Changes in holding potential (Vh), affect both gating charge (the Q(Vh) curve) and peak ionic current (the F(Vh) curve) seen at positive test potentials. Careful comparison of the Q(Vh) and F(Vh) distributions indicates that these curves are similar, having two slopes (approximately 2.5e for Vh from -115 to -90 mV and approximately 4e for Vh from -90 to -65 mV) and very negative midpoints (approximately -86 mV). Thus, gating charge movement and channel availability appear closely coupled under fully-equilibrated conditions. The time course by which channels approach equilibration was explored using depolarizing prepulses of increasing duration. The high slope component seen in the F(Vh) and Q(Vh) curves is not evident following short depolarizing prepulses in which the prepulse duration approximately corresponds to the settling time for fast inactivation. Increasing the prepulse duration to 10 ms or longer reveals the high slope, and left-shifts the midpoint to more negative voltages, towards the F(Vh) and Q(Vh) distributions. These results indicate that a separate slow-moving voltage sensor affects the channels at prepulse durations greater than 10 ms. Charge movement and channel availability remain closely coupled as equilibrium is approached using depolarizing pulses of increasing durations. Both measures are 50% complete by 50 ms at a prepulse potential of -70 mV, with proportionately faster onset rates when the prepulse potential is more depolarized. By contrast, charge movement and channel availability dissociate during recovery from prolonged depolarizations. Recovery of gating charge is considerably faster than recovery of sodium ionic current after equilibration at depolarized potentials. Recovery of gating charge at -140 mV, is 65% complete within approximately 100 ms, whereas less than 30% of ionic current has recovered by this time. Thus, charge movement and channel availability appear to be uncoupled during recovery, although both rates remain voltage sensitive. These data suggest that channels remain inactivated due to a separate process operating in parallel with the fast gating charge. We demonstrate that this behavior can be simulated by a model in which the fast charge movement associated with channel activation is electrostatically-coupled to a separate slow voltage sensor responsible for the slow inactivation of channel conductance.

Animals↗

PubMed1998

Cyclic AMP decreases the availability of 5-phosphoribosyl-1-pyrophosphate and decelerates de novo purine synthesis in rat hepatocytes.

Cyclic adenosine monophosphate (cAMP) was found to decrease the availability of 5-phosphoribosyl-1-pyrophosphate (PRPP) and to decelerate the rate of de novo purine synthesis in suspensions of adult rat hepatocytes. Glucagon did not affect these parameters. The glucagon antagonist des-His1[Glu9]glucagon amide (DHGA), and the protein kinase C activator 1,2-dioctanoyl-sn-glycerol (DOG) were also found to lower PRPP availability. Incubation of the hepatocytes with dbcAMP or with DHGA, did not alter the activity of PRPP synthetase in the hepatocyte lysates, indicating that the above effects are not mediated through the activity of this enzyme. The possibility that the decrease in PRPP availability reflects increased consumption associated with accelerated pyrimidine synthesis is discussed. The decelerated rate of de novo purine synthesis is probably secondary to the decreased PRPP availability.

Animals↗