From pharmacogenomics to improved patient outcomes: angiotensin I-converting enzyme as an example

Here we report the utility of a molecular epidemiologic approach for common, polygenic diseases. Since 1992, the angiotensin I-converting enzyme (ACE) deletion/deletion (D/D) genotype has been linked to several cardiovascular diseases, including diabetic nephropathy. Earlier, the ACE D/D genotype had been associated with excess tissue ACE activity. We have observed an association of the ACE D/D genotype with a large number of common diseases, including chronic renal failure due to non-insulin-dependent diabetes mellitus or hypertension, hypertensive peripheral vascular disease, and emphysema [chronic obstructive pulmonary disease (COPD)]. ACE inhibitors have been in clinical use since 1977 and have a well-known safety record. Armed with the knowledge that ACE overactivity was associated with their disease, we gave what was intended to be a tissue ACE-inhibitory dose of a hydrophobic ACE inhibitor to 800 Caucasian and African-American male patients with hypertension and 200 Caucasian and African-American male patients with chronic renal failure, over a period of 3 years. We here report their outcomes, which include those of two patients with end-stage hypertensive peripheral vascular disease and one patient with end-stage emphysema (COPD). As a group, the outcomes are superior to what is available in the literature. This experience suggests the power of pharmacogenomics to improve clinical outcomes for common diseases safely, quickly, and inexpensively, if effective drugs already exist.     

Sensitivity of Escherichia coli (MutT) and human (MTH1) 8-oxo-dGTPases to in vitro inhibition by the carcinogenic metals, nickel(II), copper(II), cobalt(II) and cadmium(II)

The toxicity of Ni(II), Co(II) and Cu(II) in animals, and that of Cd(II) in cultured cells, has been associated with generation of the promutagenic lesion 8-oxo-7,8-dihydroguanine (8-oxoguanine) in DNA, among other effects. One possible source of this base may be 8-oxo-7,8- dihydro-2'-deoxyguanosine-5'-triphosphate (8-oxo-dGTP), a product of oxidative damage to the nucleotide pool, from which it is incorporated into DNA. To promote such incorporation, the metals would have to inhibit specific cellular 8-oxo-dGTPases that eliminate 8-oxo-dGTP from the nucleotide pool. The present study was designed to test such inhibition in vitro on 8-oxo-dGTPases from two different species, the human MTH1 protein and Escherichia coli MutT protein. In the presence of Mg(II), the natural activator of 8-oxo-dGTPases, all four metals were found to inhibit both enzymes. For MTH1, the IC50 values (+/- SE; n = 3-4) were 17 +/- 2 microM for Cu(II), 30 +/- 8 microM for Cd(II), 376 +/- 71 microM for Co(II) and 801 +/- 97 microM for Ni(II). For MutT, they were 60 +/- 6 microM for Cd(II), 102 +/- 8 microM for Cu(II), 1461 +/- 96 microM for Ni(II) and 8788 +/- 1003 microM for Co(II). Thus, Cu(II) and Cd(II) emerged as much stronger inhibitors than Ni(II) and Co(II), and MTH1 appeared to be generally more sensitive to metal inhibition than MutT. Interestingly, in the absence of Mg(II), the activity of the enzymes could be restored by Co(II) to 73% of that with Mg(II) alone for MutT, and 34% for MTH1, the other metals being much less or non-effective. The difference in sensitivity to metal inhibition between the two enzymes may reflect the differences in the amino acid ligands, especially the cysteine ligand, outside their evolutionarily conserved Mg(II)-binding active sites, which might indicate predominantly non-competitive or uncompetitive mechanism of the inhibition. The overall results suggest that inhibition of 8-oxo- dGTPases may be involved in the mechanisms of induction of the 8- oxoguanine lesion in DNA by the metal ions studied, especially the non- redox-active Cd(II) cation.      

The optimal outcomes of post-hospital care under medicare

OBJECTIVE: To estimate the differences in functional outcomes attributable to discharge to one of four different venues for post-hospital care for each of five different types of illness associated with post-hospital care: stroke, chronic obstructive pulmonary disease (COPD), congestive heart failure (CHF), hip procedures, and hip fracture, and to estimate the costs and benefits associated with discharge to the type of care that was estimated to produce the greatest improvement. STUDY SETTING/DATA SOURCES: Consecutive patients with any of the target diagnoses were enrolled from 52 hospitals in three cities. Data sources included interviews with patients or their proxies, medical record reviews, and the Medicare Automated Data Retrieval System. ANALYSIS: A two-stage regression model looked first at the factors associated with discharge to each type of post-hospital care and then at the outcomes associated with each location. An instrumental variables technique was used to adjust for selection bias. A predictive model was created for each patient to estimate how that person would have fared had she or he been discharged to each type of care. The optimal discharge location was determined as that which produced the greatest improvement in function after adjusting for patients' baseline characteristics. The costs of discharge to the optimal type of care was based on the differences in mean costs for each location. DATA COLLECTION/EXTRACTION METHODS: Data were collected from patients or their proxies at discharge from hospital and at three post-discharge follow-up times: six weeks, six months, and one year. In addition, the medical records for each participant were abstracted by trained abstractors, using a modification of the Medisgroups method, and Medicare data were summarized for the years before and after the hospitalization. PRINCIPAL FINDINGS: In general, patients discharged to nursing homes fared worst and those sent home with home health care or to rehabilitation did best. Because the cost of rehabilitation is high, greater use of home care could result in improved outcomes at modest or no additional cost. CONCLUSIONS: Better decisions about where to discharge patients could improve the course of many patients. It is possible to save money by making wiser discharge planning decisions. Nursing homes are generally associated with poorer outcomes and higher costs than the other post-hospital care modalities.     

Cardiac rhabdomyomas and their association with tuberous sclerosis

A search for children presenting with signs or symptoms of cardiac rhabdomyomas was made through members of the paediatric section of the British Cardiac Society in order to establish their birth incidence, presenting features, clinical course, and the frequency of a concurrent diagnosis of tuberous sclerosis. Fifteen children were identified and 12 had tuberous sclerosis (80%). Heart failure was the presentation in six, five of whom died; six presented because of a murmur and three because of arrhythmias. The prevalence of echocardiographic evidence of cardiac rhabdomyomas in a population of patients with tuberous sclerosis was established. Twenty individuals had echocardiography and eight had echodensities consistent with cardiac rhabdomyomas. It is concluded that the minimum birth incidence for children presenting because of the effects of cardiac rhabdomyomas is 1/326,000 and a minimum of 80% have tuberous sclerosis. In a population of patients with tuberous sclerosis a minimum of 60% under 18 years have cardiac rhabdomyomas.     

Outcome of congenital lung abnormalities detected antenatally

To determine the outcome of congenital lung abnormalities, data were collected retrospectively between January 1991 and December 1996 on any foetus found to have a lung lesion on antenatal ultrasound. A total of 23 foetuses had lung lesions on antenatal ultrasound. In two foetuses the antenatal ultrasound showed bilateral enlarged "bright" echogenic lungs with evidence of hydrops. Both pregnancies were terminated and tracheal atresia was confirmed. In 15 foetuses the antenatal ultrasound appearance was of a unilateral "bright" echogenic lung. There was one case of bronchial atresia and two cases of congenital lobar emphysema, which all had surgery. In nine cases there was a reduction in the size of the lesion on serial antenatal ultrasounds and no lesion was detected after birth. In three cases a small lesion was present after birth on chest radiography. In six foetuses the antenatal ultrasound appearance was of unilateral cystic or mixed cystic and echogenic lung lesions. Two pregnancies were terminated; both had congenital cystic adenomatoid malformation. Four pregnancies were continued and three infants had surgery soon after birth and were confirmed to have had congenital cystic adenomatoid malformation. One infant has been managed conservatively. In conclusion, a definitive diagnosis cannot usually be made antenatally. A large lesion on initial scan does not necessarily predict a poor outcome. The natural history of small asymptomatic postnatal lesions is unknown and a long-term prospective study is needed to determine the outcome of these lesions.     

Surface electrical stimulation versus brace in treatment of idiopathic scoliosis

Surface electrical stimulation using the ScoliTron device was applied to 40 adolescent patients for treatment of idiopathic scoliosis. Adequate follow-up was available for 30 of these patients. The overall failure rate was 15 of 30 or 50%. Due to curve progression while using the ScoliTron, these patients either went on to a fusion (9 of 15) or were changed to a brace (6 of 15). The remaining 15 patients were considered successes with no curve progression (10 of 30 or 33%) or successful/failures with slight curve progression not requiring a change in treatment (5 of 30 or 17%). None of the various parameters analyzed were found to be useful indicators of successful treatment using the ScoliTron device. Electrical stimulation was found to be ineffective in preventing curve progression for idiopathic scoliosis.     

GABAA-receptor-mediated effects of progesterone, its ring-A-reduced metabolites and synthetic neuroactive steroids on neurogenic oedema in the rat meninges.

1. The effects of progesterone, its A-ring-reduced metabolites, allopregnanolone, tetrahydroxydeoxycorticosterone and the synthetic neuroactive steroid alphaxalone were evaluated in a rat model of plasma extravasation within the meninges following unilateral electrical stimulation (ES) of the trigeminal ganglion (0.6 mA, 5 ms, 5 min) or substance P administration (1 nmol kg-1, i.v.). 2. When administered 55 min prior to electrical stimulation, progesterone (> or = 500 micrograms, s.c.) dose-dependently decreased plasma extravasation within the meninges (ED50: 650 micrograms) but not within conjunctiva and tongue. Promegestone (R5020), a non-metabolized progesterone agonist (1000 micrograms, i.p.) was ineffective. The administration of progestrone (> or = 500 micrograms s.c.) 55 min prior to substance P partially suppressed plasma extravasation within the meninges (ED50: 550 micrograms). 3. The GABAA-antagonist, bicuculline (ED50: 8.2 micrograms kg-1, i.p.) but not the GABAB-antagonist, phaclofen (100 micrograms kg-1, i.p.) attenuated the effects of progesterone after electrical stimulation and substance P administration. 4. The metabolites of progesterone, allopregnanolone (3 alpha-hydroxy-5 alpha- pregnan-20-one (THP); ED50: 0.58 micrograms kg-1, i.p.), tetrahydroxydeoxycorticosterone (3 alpha,21- dihydroxy-5 alpha-pregnan-20-one (THDOC); ED50: 1.2 micrograms kg-1, i.p.) as well as the synthetic steroid alphaxalone (3 alpha-hydroxy-5 alpha-pregnane-11,20-dione; ED50: 1.8 micrograms kg-1, i.p.) suppressed plasma extravasation dose-dependently following ES, whereas the epimer of allopregnanolone, 3 beta-hydroxy-5 alpha-pregnan-20-one (100 micrograms kg-1, i.p.), did not. Extravasation caused by SP administration was partially suppressed by allopregnanolone (> or = 1 microgram kg-1, i.p.) (ED50: 2.1 micrograms kg-1). 5. The effect of progesterone (1000 micrograms, s.c.) and allopregnanolone (100 micrograms kg-1, i.p.) on neurogenic plasma extravasation was reversed by bicuculline (10 micrograms kg-1, i.p.) or by a congener, bicuculline-methiodide (10 micrograms kg-1, i.p.) which does not cross the blood brain barrier. 6. Progesterone (1000 micrograms, s.c.) had no effect on mean arterial blood pressure or heart rate when measured for 60 min after administration. 7. These results indicate that neurosteroid modulation of a GABAA-receptor located outside the blood brain barrier suppresses neurogenic and substance P-induced plasma extravasation within the meninges. The findings are consistent with previously reported data showing that valproic acid and muscimol inhibit meningeal oedema by bicuculline-sensitive mechanisms. Drugs which activate GABAA-receptors and its modulatory sites might be clinically effective in the treatment of migraine and cluster headache.     

Effects of marihuana on auditory signal detection

23 male subjects were tested for auditory signal detection under a no-treatment condition, and smoke marihuana conditions containing 0, 50, 100 and 200 g ⁹-THC per kg body weight. Signal detection was measured under conditions of concentrated attention, in which the subject reported the presence or absence of a tone in a 3-sec noise burst; and divided attention, where the subject also repeated a series of six digits which were presented simultaneously with the noise burst. No differences were found between the no-treatment and placebo conditions. Significant dose-dependent impairment of signal detection resulted for the marihuana conditions under both concentrated and divided attention. Application of signal detection theory indicated that impaired performance was due to a decline in sensitivity (d), independent of changes in subject criteria (beta). There was also some indication of change in criteria—a greater tendency for erroneous reporting of a signal when it was not present.This work was supported by the National Highway Traffic Safety Administration DOT HS-150-2-236, the National Institute of Mental Health MH-17864 and K05-DA-70182, and the National Institute of Alcohol Abuse and Alcoholism AA-00251.