Adolescent exposure to sucrose increases cocaine-mediated behaviours in adulthood via Smad3

Adolescence, a critical period of developmental period, is marked by neurobiological changes influenced by environmental factors. Here, we show how exposure to sucrose, which is ubiquitously available in modern diets, results in changes in behavioural response to cocaine as an adult. Rats were given daily access to either 10% sucrose or water during the adolescent period (PND28-42). Following this period, rats are left undisturbed until they reach adulthood. In adulthood, rats were tested for (i) acquisition of a low dose of cocaine, (ii) progressive ratio (PR) test, and (iii) resistance to punished cocaine taking. Sucrose exposure resulted in significant alterations in all behavioural measures. To determine the neurobiological mechanisms leading to such behavioural adaptations, we find that adolescent sucrose exposure results in an upregulation of the transcription factor Smad3 in the nucleus accumbens (NAc) when compared with water-exposed controls. Transiently blocking the active form of this transcription factor (HSV-dnSmad3) during adolescence mitigated the enhanced cocaine vulnerability-like behaviours observed in adulthood. These findings suggest that prior exposure to sucrose during adolescence can heighten the reinforcing effects of cocaine. Furthermore, they identify the TGF-beta pathway and Smad3 as playing a key role in mediating enduring and long-lasting adaptations that contribute to sucrose-induced susceptibility to cocaine. Taken together, these results have important implications for development and suggest that adolescent sucrose exposure may persistently enhance the susceptibility to substance abuse.

Operant novelty seeking predicts cue-induced reinstatement following cocaine but not water reinforcement in male rats

RATIONALE

An important facet of cocaine addiction is a high propensity to relapse, with increasing research investigating factors that predispose individuals toward uncontrolled drug use and relapse. A personality trait linked to drug addiction is high sensation seeking, i.e., a preference for novel sensations/experiences. In an animal model of sensation seeking, operant novelty seeking predicts the acquisition of drug self-administration.

OBJECTIVE

The primary goal of this research was to evaluate the hypothesis that sensitivity to the reinforcing effects of novel sensory stimuli predicts more intensive aspects of drug-taking behaviors, such as relapse.

METHODS

Rats were first tested for Operant Novelty Seeking, during which responses resulted in complex visual/auditory stimuli. Next, rats were trained to respond to water/cocaine reinforcers signaled by a cue light. Finally, rats were exposed to extinction in the absence of discrete cues and subsequently tested in a single session of cue-induced reinstatement, during which active responses resulted in cues previously paired with water/cocaine delivery.

RESULTS

The present study showed operant responses to produce novel sensory stimuli positively correlate with responding for cocaine during self-administration and during discrete cue-induced reinstatement, but no association with performance during extinction. A different pattern of associations was observed for a natural reward, in this case, water reinforcement. Here, the degree of novelty seeking also correlated with responding to water reinforcement and extinction responding; however, operant novelty seeking did not correlate with responding to water cues during testing of cue-induced reinstatement. Taken together, the incongruence of relationships indicates an underlying difference between natural and drug reinforcers.

CONCLUSION

In summary, we found a reinforcer-dependent relationship between operant novelty seeking (i.e., sensation seeking) and responsivity to extinction and discrete cues signaling availability for cocaine (i.e., craving), demonstrating the validity of the operant novelty seeking model to investigate drug seeking and relapse.

Cost of treating influenza in emergency department and hospital settings

OBJECTIVES

To provide an estimate of the costs of treating influenza in emergency department and hospital settings.

STUDY DESIGN

Retrospective, descriptive study using patient-level data from the Perspective Comparative Database.

PATIENTS AND METHODS

We analyzed clinical and cost data obtained from 75 of the 169 hospitals in the database. These hospitals were located throughout the United States. Patients were included in the study if they visited the emergency department between January 1, 1997, and June 30, 1998, and had a primary diagnosis of influenza.

RESULTS

A total of 1362 patients with influenza visited the emergency department during the study period. Of these, 333 (24.4%) required hospitalization. The mean cost of treatment for patients discharged directly from the emergency department was $141.89; the mean cost of treatment for hospitalized patients was $3251.04. The mean length of stay for hospitalized patients was 4.3 days. Compared with younger patients, elderly patients were more likely to be hospitalized and incur higher costs. Thirty-eight percent of hospitalized patients for whom drug data were available received either amantadine or rimantadine during their stay.

CONCLUSIONS

Few data are available documenting resource utilization and associated costs for patients with influenza treated in the emergency department or hospital. Our results represent a significant addition to the identification of the costs associated with the treatment of influenza. This suggests early intervention care aimed at minimizing the impact of influenza, especially in the elderly, could result in decreased hospitalizations and substantial cost savings to managed care.

Comparison of cefuroxime axetil and amoxicillin/clavulanate in the treatment of acute bacterial sinusitis

This double-masked, multicenter, randomized clinical trial compared the efficacy and tolerability of cefuroxime axetil and amoxicillin/clavulanate in the treatment of acute bacterial maxillary sinusitis. A total of 263 patients with acute bacterial maxillary sinusitis were randomly assigned to receive 10 days of treatment with either cefuroxime axetil 250 mg twice daily (n = 132) or amoxicillin/clavulanate 500/125 mg 3 times daily (n = 131). Patients' responses to treatment were assessed once during treatment (6 to 8 days after the start of treatment), at the end of treatment (1 to 3 days posttreatment), and at follow-up (26 to 30 days after cessation of treatment). Clinical success, defined as cure or improvement, was equivalent in the cefuroxime axetil and amoxicillin/ clavulanate groups at the end-of-treatment and follow-up assessments. Patients in both groups showed improvements in symptoms of acute sinusitis at the during-treatment visit. Treatment with amoxicillin/clavulanate was associated with a significantly higher incidence of drug-related adverse events than treatment with cefuroxime axetil (29% vs 17%), primarily reflecting a higher incidence of gastrointestinal adverse events (23% vs 11%), particularly diarrhea. Two patients in the cefuroxime axetil group and 8 patients in the amoxicillin/clavulanate group withdrew from the study due to adverse events (P = 0.06). These results indicate that cefuroxime axetil 250 mg twice daily is as effective as amoxicillin/clavulanate 500 mg 3 times daily in the treatment of acute sinusitis and produces fewer gastrointestinal adverse events. cefuroxime axetil, amoxicillin/clavulanate, acute sinusitis.

Comparative effect of dietary sitosterol on plasma sterols and cholesterol and bile acid synthesis in a sitosterolemic homozygote and heterozygote subject

OBJECTIVE

Sitosterolemia is a genetic disorder characterized by an increased plasma plant sterol concentration due to enhanced sterol absorption coupled with reduced steroid excretion. The purpose of the present investigation was two-fold; first to assess the effects of a "basal" low sitosterol metabolic diet on plasma sterols and sterol balance, and, secondly, to quantify the relative influence of graduated increase in dietary sitosterol intake on a metabolic diet in a sitosterolemic homozygote, obligate heterozygote, and controls.

METHODS

Patients were studied under strict metabolic conditions and fed a "basal" 30% fat, low-sitosterol (33 mg per 2000 kcal) diet. The level of dietary sitosterol was increased by addition of oils and resulted in final dietary sitosterol intakes of 1.8 mg/kg, 2.6 mg/kg and 3.5 mg/kg/day intakes of dietary sitosterol in the homozygote. These sitosterol dosages were selected based on sitosterol intakes equivalent to 2.6 mg/kg/day in the average American diet. Plasma cholesterol, sitosterol, and apolipoprotein A were measured, and stool collections assayed for sterol balance.

RESULTS

Fecal sterol excretion and cholesterol synthesis were depressed markedly by 50% in the homozygote compared to the heterozygous parent, whereas plasma sitosterol levels were increased over 50-fold. When the sitosterol content of the diet was increased three-fold and dietary cholesterol was maintained in the homozygous and hypercholesterolemic control, plasma levels did not increase in the homozygote. Plasma cholesterol and sitosterol levels were unaffected in the hypercholesterolemic control.

CONCLUSIONS

Plasma sterol levels remained elevated with the dietary sitosterol changes in the sitosterolemic homozygote. These findings were associated with a low fecal sterol excretion rate and depressed endogenous cholesterol synthesis. In this sitosterolemic patient, a very low sitosterol diet to curtail sterol input was of minimal therapeutic benefit. These results have important implications regarding the selection of therapy for this patient under these experimental conditions, but cannot be generalized to other homozygotes.

Sitosterolemia: opposing effects of cholestyramine and lovastatin on plasma sterol levels in a homozygous girl and her heterozygous father

Sitosterolemia is a genetic disorder characterized by sitosterol accumulation in plasma and clinically accelerated atherosclerosis. Under a condition of metabolic control with a 30% fat, low-sitosterol diet, we compared the effects of monotherapy and dual-drug treatment with lovastatin and cholestyramine on plasma sterol parameters and endogenous cholesterol synthesis in a homozygous sitosterolemic patient with concomitant heterozygous familial hypercholesterolemia (FH), her obligate heterozygous father, and hyperlipidemic control subjects. We found that for both the sitosterolemic homozygote and heterozygote, cholestyramine plus lovastatin dual therapy proved not to be superior to either drug treatment alone. In the homozygous patient, cholestyramine accounted for the decrease of plasma sterol (ie, lovastatin was ineffective), whereas in the heterozygote, lovastatin represented the margin of difference (ie, low-dose cholestyramine was relatively ineffective). Thus, the best treatment option for this homozygote child and her heterozygote father appears to be monotherapy with cholestyramine and lovastatin, respectively. Stimulation by bile acid malabsorption produced a dramatic decrease of plasma sterols in the homozygote, without increasing endogenous cholesterol synthesis, but this therapy was ineffective in the heterozygote. Decreasing endogenous cholesterol synthesis with lovastatin was effective in the heterozygote, but ineffective in the homozygote. In suspected sitosterolemia, a poor sterol response to lovastatin and a dramatic response to cholestyramine may differentiate homozygous from heterozygous and other familial forms of hyperlipidemia.

Determinants of plasma cholesterol responsiveness to diet

Plasma cholesterol change, or 'responsiveness', to dietary saturated fat modification has long been acknowledged. The present study sought to determine the specific, predicted response of each cholesterol subfraction to known dietary manipulations. Two metabolically controlled diets, one with a low polyunsaturated:saturated fat (low P:S) ratio, and one with a high P:S ratio were fed in a crossover design to sixty-seven normolipidaemic subjects pooled from six foregoing metabolic studies. A series of statistical analyses was performed to identify the lipids and subfractions independently affected by the diet crossover. Multivariate analysis of variance revealed that the changes in total cholesterol (delta TC), low-density-lipoprotein-cholesterol (delta LDL-C), and high-density-lipoprotein-cholesterol (delta HDL-C) were the only statistically significant diet-specific 'responsive' lipids. Multiple regression was performed to identify the independent predictors of delta TC, delta LDL-C and delta HDL-C. It was found that age (years), extent of change in dietary saturated fat, and baseline LDL-C (mg/l) levels determine LDL-C change, while extent of change in saturated and polyunsaturated fat, and baseline HDL-C (mg/l) levels can predict HDL-C change. A series of equations to predict lipoprotein responsiveness to diet are derived for potential use in clinical practice.

Low-density lipoprotein cholesterol responsiveness to diet in normolipidemic subjects

Both apolipoprotein E genotype (apo E) and diet predict very-low-density (VLDL-C) and low-density lipoprotein cholesterol (LDL-C) levels. In a retrospective pooled analysis of six studies, we sought to identify the predictors of VLDL-C and LDL-C change, or "responsiveness," to a diet crossover. "Response" to diet was studied in 67 normolipidemic subjects of common apo E genotype. Subjects were fed two contrasting, metabolically controlled diets: one had a low polyunsaturated to saturated fatty acid ratio (P:S), and the other had a high P:S ratio. Multiple blood samples were analyzed for VLDL-C and LDL-C levels at the end of each metabolic diet period, and values were averaged and differences were calculated. Despite adjustment for significant predictors across the component studies, a wide range of LDL-C responsiveness was found, with an average decrease of 28 mg/dL. Multivariate regression analysis was used to identify the most significant predictors of LDL-C response to the diet crossover. All dietary and clinical variables were entered by stepwise regression for potential inclusion in a "best-fit" model. The degree of change in saturated fat content and age were the most significant predictors of LDL-C responsiveness. Neither dietary cholesterol nor apo E phenotype were significant predictors of responsiveness. The most LDL-C-responsive subjects were older and required smaller reductions in dietary saturated fat levels than did less-responsive subjects to achieve a comparable reduction in LDL-C levels. Multiple regression analysis suggested a precursor-product relationship between VLDL-C and LDL-C responsiveness.

Influence of dietary fat, apolipoprotein E phenotype, and sex on plasma lipoprotein levels

BACKGROUND

The "Western" diet, sex, and apolipoprotein (Apo) E polymorphism have been implicated as codeterminants of lipid levels.

METHODS AND RESULTS

In a retrospective analysis, we evaluated the combined impact of dietary fat, sex, and Apo E phenotype on lipoprotein levels in 67 subjects fed two contrasting, metabolically controlled diets: one a "Western" diet, with a low polyunsaturated to saturated (P:S) fatty acid ratio and the other a "therapeutic" diet, with a high P:S ratio. The high P:S diet compared with P:S diet exerted a far stronger predictive influence on lipoprotein concentrations than Apo E phenotype, sex, or the latter two factors combined. Apo E phenotype alone was associated with a stepwise increase in low density lipoprotein cholesterol (LDL-C), such that 3/2 less than 3/3 less than 4/3 on either the low or the high P:S diets. On the low P:S diet only, sex was shown to be a significant predictor of high density lipoprotein cholesterol (HDL-C) levels, with women greater than men, and the associated LDL/HDL ratio with men greater than women. On the high P:S diet, women displayed a dramatic fall in HDL-C, effectively raising the LDL/HDL ratio to equivalency with men and obliterating the sex influence seen with the low P:S diet. Controlled for dietary fat, Apo E and sex exerted independent, additive effects on lipoprotein levels on the low P:S diet only. Only the Apo E phenotype remained predictive on the high P:S diet.

CONCLUSIONS

Women of the Apo E 3/2 phenotype stand to benefit the least from a high P:S diet because of reduction in the more "protective" HDL-C, whereas men of the 4/3 phenotype showed the greatest improvement in the LDL/HDL ratio.

Lovastatin efficacy in reducing low-density lipoprotein cholesterol levels on high- vs low-fat diets

The effectiveness of lovastatin was compared with both a high-fat vs low-fat diet. Hypercholesterolemic subjects were studied under metabolic ward conditions for diet periods of 3 weeks while receiving lovastatin (40 mg/d) or placebo. Multiple lipoprotein levels were measured during the final week of each diet period. Nineteen subjects completed the study on the high-fat (43% of kilojoules) diet and 16 on the low-fat (25% of kilojoules) diet. Lovastatin reduced total cholesterol by 23% and low-density lipoprotein cholesterol by 30%, compared with placebo on both diets, with no significant diet-drug interaction. High-density lipoprotein cholesterol was raised by 7% to 8% on the diet regimens. Addition of lovastatin to the low-fat diet permitted 80% of subjects on this diet, but less than 50% of those on the high-fat diet, to achieve current guidelines. Although lovastatin produces a comparable percentage reduction in lipoprotein profiles on either diet, the accompanying low-fat diet remains advisable for additional reduction of low-density lipoprotein cholesterol levels to specified goals.