Patient characteristics and costs associated with dyslipidaemia and related conditions in HIV-infected patients: a retrospective cohort study

BACKGROUND

Metabolic abnormalities are common in HIV-infected individuals and, although multifactorial in origin, have been strongly associated with antiretroviral therapy.

METHODS

Using automated claims and clinical databases, combined with medical record data, we evaluated the burden of dyslipidaemia (DYS) and associated metabolic abnormalities among a cohort of 900 HIV-infected patients aged 18 years and older who received their care from a large multispecialty medical group between 1 January 1996 and 30 June 2002. A Cox proportional hazards model for DYS was developed. Resource use was compiled and subsequently costed with stratification to account for variable length of follow-up.

RESULTS

Mean follow-up time was 3.3 years. DYS was present in 54% of the cohort and 3.4% experienced a cardiovascular (CV) event. Both unadjusted and adjusted results found patients with dyslipidaemia and cardiovascular events significantly more likely to have received protease inhibitor (PI) treatment for longer periods of time. In the Cox proportional hazards model the following factors were significantly associated with an increased risk for DYS: older age, white race, PI use and male sex. Diagnoses of hypertension, hepatitis C virus infection, depression or opportunistic infections were all negatively associated with a DYS diagnosis. When controlled for length of follow up, patients with DYS (and no CV-related events) incurred greater median and mean total average costs than patients without DYS or CV-related events. For patients with more than 2 years of follow up, these total cost differences were statistically significant (P<0.05).

CONCLUSIONS

These findings indicate that DYS is common among patients with HIV infection and is associated with increased use of medical resources.

Modulation of A(beta) peptides by estrogen in mouse models

Clinical studies have shown that estrogen deprivation through menopause is a risk factor in both the initiation and progression of Alzheimer's disease (AD) and that estrogen replacement therapy may be protective. One of the major pathological features in the human AD brain is the senile plaque, a proteinaceous structure composed mainly of heterogeneous peptides collectively known as A-beta (A(beta)). In vitro studies have linked estrogen with A(beta) modulation, suggesting that one-way that estrogen depletion at menopause may exacerbate the features of AD is through A(beta) accumulation. To test this, two studies were performed on transgenic models of amyloidosis. Firstly, transgenic mice without detectable amyloid aggregates were subjected to ovariectomy and estradiol supplementation, and A(beta) levels were assessed. Secondly, the effects of estrogen modulation were assessed in mice at an age when plaques would be forming initially. Overall, A(beta) levels were higher in estrogen-deprived mice than intact mice, and this effect could be reversed through the administration of estradiol. These data suggest that, in vivo, estrogen depletion leads to the accumulation of A(beta) in the CNS, which can be reversed through replacement of estradiol. These results provide evidence that post-menopausal estrogen depletion may be linked to an increased risk of AD through A(beta) modulation.

Accelerated carotid artery disease after high-dose head and neck radiotherapy: is there a role for routine carotid duplex surveillance?

PURPOSE

High-dose external radiotherapy used in the treatment of head and neck carcinoma has been implicated as a risk factor for accelerated atherosclerotic disease of the carotid arteries. However, how radiotherapy affects atherosclerotic disease is controversial, and little data exist to demonstrate a strong relationship between radiotherapy and progressive carotid disease.

METHODS

We performed a retrospective chart review of 69 patients (all men) who underwent duplex ultrasound scanning examinations for carotid disease between 1993 and 1998. Twenty-three patients had received high-dose radiotherapy for the treatment of head and neck carcinoma within the past 12 years (group 1; mean age, 67.8 years), and 46 patients were randomly selected as age-matched control subjects (group 2; mean age, 68.3 years). The mean radiation dose was 6060 +/- 182 rads, and the average interval between radiotherapy and ultrasound scanning was 6. 5 +/- 1.8 years. There was no significant difference between the two groups in the presence of these comorbidities: diabetes mellitus, coronary artery disease, hypertension, tobacco use, hypercholesterolemia, peripheral vascular disease, or stroke. Similarly, there was no difference in the indications for the duplex scanning studies.

RESULTS

Five of the 23 patients in group 1 (21. 7%) were found to have advanced carotid disease (70% to 99% stenosis); four patients were symptomatic, three patients went on to endarterectomy, and one patient was awaiting surgery. Two of the 46 patients in the control group (4%) had advanced carotid disease. One patient was symptomatic, and both patients underwent endarterectomy. A significant difference in the prevalence of advanced disease between the two groups was noted (P =.037). Sixteen patients who survived irradiation underwent a second duplex scanning study and had evidence of progressive disease with significant increases in peak systolic velocities.

CONCLUSION

High-dose radiotherapy to the head and neck region may be a significant risk factor for accelerated carotid atherosclerotic disease. Routine carotid duplex surveillance may be warranted in this high-risk patient population.

Synthesis and evaluation of brain-targeted chemical delivery systems for the neurotrophomodulator 4-methylcatechol

Since various 4-alkylcatechols stimulate nerve growth factor (NGF) biosynthesis both in-vitro and in-vivo, delivery of these agents to the brain may provide beneficial effect for the treatment of neurodegenerative diseases such as Alzheimer's. Several dihydropyridine-pyridinium salt type redox chemical delivery systems (CDS) of 4-methylcatechol (4-methylcatechol) were prepared as potential brain selective targetry forms for 4-methylcatechol. After preliminary evaluation by in-vitro stability studies in various buffer solutions and biological media, a selected CDS was further investigated in the rat to determine its in-vivo distribution. Selective and sustained delivery of the compound of interest to the rat brain was achieved. Furthermore, the NGF stimulatory activity in the rat brain after peripheral administration of the selected CDS was evaluated by measuring the levels of pre-pro-NGF mRNA in the rat hippocampus and frontal cortex, by dot blot hybridization and analysis. Results showed the peripheral administration of the CDS to achieve a 1.7-fold increase in NGF mRNA compared to control in the rat hippocampus, and an approximately 1.4-fold increase in the frontal cortex.

Analgesic and immunomodulatory effects of codeine and codeine 6-glucuronide

PURPOSE

The antinociceptive and immunosuppressive effects of codeine and codeine 6-glucuronide were determined in rats after intracerebroventricular administration.

METHODS

Codeine 6-glucuronide was synthesized using a modification of the Koenigs-Knorr reaction. A lipophilic intermediate formed during synthesis, methyl [codein-6-yl-2,3,4-tri-O-acetyl-beta-D-glucopyranosid] uronate, was also tested. Morphine was used as a positive control to compare antinociceptive potencies of these compounds.

RESULTS

All compounds tested produced significant analgesic responses, as assessed by the tail flick model. Additionally, codeine 6-glucuronide showed significantly less immunosuppressive effects than codeine in vitro.

CONCLUSIONS

We conclude that codeine 6-glucuronide and related compounds may have clinical benefit in the treatment of pain in immune compromised patients.

A strategy for delivering peptides into the central nervous system by sequential metabolism

Most peptides do not enter the central nervous system because of their hydrophilic character and the presence of peptidolytic enzymes in the lipoidal blood-brain barrier. To achieve brain delivery of a peptide conjugate, an opioid peptide (enkephalin) was placed in a molecular environment that disguises its peptide nature and provides biolabile, lipophilic functions to penetrate the blood-brain barrier by passive transport. The strategy also incorporates a 1,4-dihydrotrigonellinate targetor that undergoes an enzymatically mediated oxidation to a hydrophilic, membrane-impermeable trigonellinate salt. The polar targetorpeptide conjugate that is trapped behind the lipoidal blood-brain barrier is deposited in the central nervous system. Analgesia was observed with "packaged" enkephalin but not with the unmodified peptide or lipophilic peptide precursors.

Inhibition by prolactin of post-castration rise in LH

Castration of male and female rats resulted in a marked rise in serum LH. The rise in serum LH was partially or completely prevented by injection of prolactin (Prl), by implantation of a small amount of Prl in the median eminence (ME), by grafting 2 anterior pituitaries (APs) underneath the kidney capsule, or by transplantation of a Prl-secreting pituitary tumor underneath the skin. The larger pituitary tumor transplants secreted more Prl and were more effective in reducing LH release than the smaller tumors which secreted less Prl. Suppression of LH release generally was greater during the earlier than in the later phases of the different treatments. The pituitary LH response to synthetic LH-RH was the same in ovariectomized rats with or without pituitary grafts, and the decrease in hypothalamic LH-RH after orchidectomy was prevented by pituitary grafts. These results indicate that Prl can depress LH release after castration and that these effects are mediated via the hypothalamus.

Selective actions of prolactin on catecholamine turnover in the hypothalamus and on serum LH and FSH

The effects of prolactin (PRL) administration on catecholamine turnover in various brain regions of ovariectomized rats were determined by observing the decline of dopamine and norepinephrine concentrations after alpha-methyltyrosine (alphaMT) administration. PRL had no effect on the steady state concentration of dopamine in the median eminence, anterior hypothalamus and corpus striatum or on the norepinephrine concentration in the anterior hypothalamus. However, PRL selectively enhanced dopamine turnover in the median eminence and anterior hypothalamus after a latent period of 10-26 h. In addition, PRL administration significantly decreased serum concentrations of LH and FSH. These results suggest that the PRL-induced increase in activity of dopaminergic neurons in the median eminence or anterior hypothalamus may be responsible for the reduction of the post-castration rise in serum concentrations of LH and FSH.

Differential effects of dopamine agonists and haloperidol on release of prolactin, thyroid stimulating hormone, growth hormone and luteinizing hormone in rats

The dose-response effects of apomorphine and ET-495 (piribedil), 2 specific dopamine (DA) receptor stimulators, and haloperidol, a DA receptor blocker, were tested on the secretion of prolactin (PRL), thyroid stimulating hormone (TSH), growth hormone (GH) and luteinizing hormone (LH) in male rats. Both apomorphine and piribedil reduced serum PRL and TSH levels, stimulated GH release at low but not at high doses and either had no effect or tended to reduce serum LH levels. The minimal effective dose of apomorphine for reducing PRL by 30 min was 0.01 mg/kg; TSH inhibition was observed with a dose of 0.1-0.3 mg/kg. The inhibitory effects of apomorphine (1.0 mg/kg) on PRL and TSH levels were maximal by 15 min and diminished by 120 min; plasma GH was highest 120 min after injection. Thyroidectomy (10 days) markedLH elevated serum TSH, had no effect on serum PRL and inhibited the ability of apomorphine (0.1 or 0.3 mg/kg) to reduce TSH but not PRL levels. These observations may indicate that separate dopaminergic control mechanisms exist for TSH and PRL secretion. Administration of haloperidol elevated serum PRL, tended to lower TSH, dramatically reduced GH and had no effect on LH levels. Haloperidol pre-treatment blocked the effects of apomorphine on PRL, TSH, and GH secretion. The overall results of this study indicate that DA agonists inhibit PRL and TSH, stimulate GH but do not stimulate LH release in male rats.