Prevalence of CYP2B6 polymorphisms in Argentinians: the role of genetic testing

CYP2B6 is a highly polymorphic isoenzyme involved in the metabolism of many drugs including cyclophosphamide, bupropion, and efavirenz. A single nucleotide polymorphism (SNP) in CYP2B6 (516G>T) resulted in decreased expression and function associated with the CYP2B6*6 haplotype. Among the clinical implications of this phenotype, decreased activation of cyclophosphamide and increased plasma levels of efavirenz associated with increased central nervous system toxicity have been reported. The frequency of the CYP2B6 (516G>T) SNP has been studied in several different populations, but there is no data regarding distribution among Argentinians. In this study, 102 DNA samples from healthy volunteers were analyzed using a polymerase chain reaction-restriction fragment length polymorphism reaction specific for the CYP2B6 (516G>T) SNP. Our results showed a prevalence of 71.08% for the G allele and 28.92% for the T allele. This was distributed as 52.9% for the GG genotype (reduced dosage required), 36.6% for the GT genotype (normal dosage range), and 10.8% for the TT genotype (high drug toxicity). There was no preferential gender distribution observed. The relatively high prevalence of the TT genotype in our population supports the clinical use of genotyping as an additional tool in personalized medicine.

Extensive sequence analysis of CFTR, SCNN1A, SCNN1B, SCNN1G and SERPINA1 suggests an oligogenic basis for cystic fibrosis-like phenotypes

The term cystic fibrosis (CF)-like disease is used to describe patients with a borderline sweat test and suggestive CF clinical features but without two CFTR(cystic fibrosis transmembrane conductance regulator) mutations. We have performed the extensive molecular analysis of four candidate genes (SCNN1A, SCNN1B, SCNN1G and SERPINA1) in a cohort of 10 uncharacterized patients with CF and CF-like disease. We have used whole-exome sequencing to characterize mutations in the CFTR gene and these four candidate genes. CFTR molecular analysis allowed a complete characterization of three of four CF patients. Candidate variants in SCNN1A, SCNN1B, SCNN1G and SERPINA1 in six patients with CF-like phenotypes were confirmed by Sanger sequencing and were further supported by in silico predictive analysis, pedigree studies, sweat test in other family members, and analysis in CF patients and healthy subjects. Our results suggest that CF-like disease probably results from complex genotypes in several genes in an oligogenic form, with rare variants interacting with environmental factors.

Circulating free testosterone in obese men after bariatric surgery increases in parallel with insulin sensitivity

BACKGROUND AND AIM

Male hypogonadism has been linked to obesity and diabetes. We aimed to study the association of changes in insulin sensitivity and testosterone levels in severe obese patients submitted to bariatric surgery.

SUBJECTS AND METHODS

Prospective intervention study with twenty consecutive patients who underwent bariatric surgery studied before and after significant weight loss. Serum testosterone, SHBG, fasting glucose, and insulin were measured among others. Free testosterone was calculated with the Vermeulen formula and insulin sensitivity with the homeostatic model assessment (HOMA).

RESULTS

At baseline, thirteen patients had low total testosterone levels, whereas eight of these patients also had free testosterone levels below the reference range obtained from the control group. After bariatric surgery total testosterone, SHBG, and free testosterone significantly increased and achieved normal values in all evaluated patients. Insulin sensitivity improved in all of them. Multivariate linear regression showed that changes in fasting glucose (β=-1.868, p=0.001), insulin (β=-3.782, p=0.001), weight (β=-0.622, p=0.002), and SHBG (β=-0.635, p=0.022) were associated with changes in free testosterone (adjusted R2=0.936, F=26.613, p=0.001). When insulin resistance calculated by HOMA was in the model instead of insulin and glucose, it also was associated (β=-3.488, p=0.008) with free testosterone (adjusted R2=0.821, F=11.111, p=0.005).

CONCLUSIONS

Circulating tes tos terone in obese men increases after bariatric surgery in parallel with an improvement in insulin sensitivity.

Clinical response at 4 months to neoadjuvant letrozole predicts distant disease free survival in postmenopausal women with stage II-III ER/PgR-positive breast cancer

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Background: Letrozole (L) is more active than tamoxifen in early stage ER[+] breast cancer both as adjuvant (BIG-98 trial) or neoadjuvant (LET-024) therapy. However, complete pathological remissions to neoadjuvant endocrine therapy are anecdotal (<5%), there are no new prognostic indicators with clinical implications. Methods: We have review our series of postmenopausal patients with stage II-III breast cancer ER/PgR[+] breast cancer treated in our institution with L as neoadjuvant therapy. All patients had completed 4 months of therapy (in the absence of PD), and had measurable clinical (or radiological) disease. An independent statistical analysis was conducted for disease free (DFS) and distant disease free survival (DDFS). Results: From IV/99 to XII/04, 107 patients fulfill the criteria. Median age 76 years (range 64 to 92); median tumour size 35 mm (range 25 to 100); cT2 75 (70%), cT3/4 32 (30%); cN[-] 83 (78%). The ORR (PR + CR) at 4 months was 63% (7 CR and 60 PR), 4 patients had PD as best response (4%) and 36 a SD (34%). Surgery was done in 63 patients (59%), including all non-responders. Only 2 patients received adjuvant CT. With a median follow-up of 32 month (range 8 to 66), 12 patients had relapsed (9 distant). The 3 years DFS and DDFS were 84% and 90% respectively. In univaried analysis: cN (p < 0.02), cT3/4 (p < 0.02), and clinical response at 4 months (CR) (p = 0.003) were related to DFS; and HER2 (p < 0.05), cN (p < 0.003), and CR (p = 0.007) with DDFS. Other factors like cT, HR-levels, or surgery were not significant. Multivariate analysis showed that only OR and cN remained independently predictive both for DFS and DDFS. Conclusions: Clinical response to neoadjuvant letrozole therapy is an independent predictor of distant disease free survival and could be of value to recommend or deny more aggressive therapies in addition to endocrine therapy.

[Table: see text]

No significant financial relationships to disclose.

Randomized comparison of efficacy of cooled tip catheter ablation of atrial flutter: anatomic versus electrophysiological complete isthmus block

There is a subset of patients with failed ablation of the cavotricuspid isthmus (CTI) using standard catheters and with 10% of the patients having recurrences. The purpose of this study was to compare the cooled and standard ablation with regard to acute successful electrophysiological achievement of bidirectional isthmus block and the subacute anatomic characteristics of the lesions. This randomized, experimental study compares the effects of ablation on the isthmus using a cooled catheter with those of a standard ablation catheter in 16 pigs. In 12 animals, CTI block was achieved after ablation (8/8 cooled and 4/8 standard). In two animals, it was not possible to achieve complete isthmus block and two had persistent slow conduction (all four using the standard catheter). After 1 week, the animals were slaughtered. The size of the lesion was greater with the irrigated tip catheters. Transmural lesions were found in 14 animals. A complete line of anatomic isthmus block was not documented after thefirst line in six animals, four with the standard and two with the cooled catheter. A conduction block was never present across gaps > or = 5 mm. In conclusion cooled catheters achieved a complete line of electrophysiological and anatomical block in a significantly higher percentage than the standard catheters.

Electron-transfer salts of 1,2,3,4,5-pentamethylferrocene, Fe(II)(C5Me5)(C5H5). Structure and magnetic properties of two 1:1 and two 2:3 Fe(C5Me5)(C5H5) electron-transfer salts of tetracyanoethylene

The reaction of Fe(II)(C5Me5)(C5H5), FeCpCp, with percyano acceptors, A [A = C4(CN)6 (hexacyanobutadiene), TCNQF4 (perfluoro-7,7,8,8-tetracyano-p-quinodimethane), and DDQ (2,3-dichloro-5,6-dicyanobenzoquinone)], results in formation of 1:1 charge-transfer salts of [Fe(III)CpCp]*]*+[A]*- composition. With A = TCNQ (7,7,8,8-tetracyano-p-quinodimethane) a 1:2 electron-transfer salt with FeCpCp forms. With A = TCNE (tetracyanoethylene) a pair of 1:1 salts as well as a pair of 2:3 salts of [FeCpCp]2[TCNE]3.S (S = CH2Cl2, THF) have been isolated and characterized by single-crystal X-ray diffraction. [FeCpCp][TCNE] consists of parallel 1-D.D(*+)A(*-)D(*+)A(*-)D(*+)A(*-). chains, while [FeCpCp][TCNE].MeCN has a herringbone array of D(*+)A2(2-)D(*+) dimers separated by solvent molecules. Although each [TCNE](-) is disordered, the diamagnetic [TCNE]2(2-) dimer is structurally different from those observed earlier with an intradimer separation of 2.79 A. The [TCNE](-) in the 2:3 [FeCpCp]2[TCNE]3.S exists as an eclipsed diamagnetic [TCNE]2(2-) dimer with an intradimer ethylene C.C separation of 2.833 and 2.903 A for the CH2Cl2- and THF-containing materials, respectively. The bond distances and angles for all the cations are essentially equivalent, and the distances are essentially equivalent to those previously reported for [FeCp2](*+) and [FeCp2](*+) cations. The average Fe-C5H5-ring and Fe-C5Me5-ring centroid distances are 1.71 and 1.69 A, respectively, which are 0.05 A longer than reported for Fe(II)CpCp. The one-electron reduction potential for Fe(II)CpCp is 0.11 V (vs SCE). The 5 K EPR of [FeCpCp](*+)[BF4](-) exhibits an axially symmetric powder pattern with g(parallel) = 4.36 and g(perpendicular) = 1.24, and the EPR parameters are essentially identical to those reported for ferrocenium and decamethylferrocenium. The high-temperature magnetic susceptibility for polycrystalline samples of these complexes can be fit by the Curie-Weiss law, chi = C/(T - theta), with low theta values and mu(eff) values from 2.08 to 3.43 mu(B), suggesting that the polycrystalline samples measured had varying degrees of orientation. [FeCpCp][TCNE] exhibits the highest effective moment of 3.43 mu(B)/Fe and weak ferromagnetic coupling, as evidenced from the theta of 3.3 K; however, unexpectedly, it does not magnetically order above 2 K. The formation of the four phases comprising FeCpCp and TCNE emphasizes the diversity of materials that may form and the present inability to predict neither solid-state compositions nor structure types.

Transient expression of nitric oxide synthase in the hypoglossal nucleus of the rat during early postnatal development

The present study investigates the presence of nitric oxide synthase (NOS) by the nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemical reaction and immunohistochemistry with neuronal NOS (nNOS) antibody during postnatal development of hypoglossal nucleus (XII) in the rat. Our results showed that the enzyme expression was limited to a subset of cells in the dorsal division of the nucleus. Retrogradely labeling with diamidino yellow (DY) from the tongue indicates that these cells were motoneurons. NOS expression was transient, being detectable during the first 3 postnatal weeks, suggesting a role for nitric oxide in the development and maturation of this subset of cranial motoneurons.

Crossover iliofemoral bypass grafting for treatment of unilateral iliac atherosclerotic disease

PURPOSE

In patients with unilateral iliac disease, a less invasive procedure than aortobifemoral bypass grafting may be desirable, especially in poor-risk patients or when sexual dysfunction is feared. In these cases, femorofemoral (FF) bypass grafting is often proposed. Compared with FF bypass grafting, iliofemoral (IF) bypass grafting avoids bilateral exposure of the groins, which may reduce the risk of infection. When the primitive iliac artery is occluded from its origin or heavily calcified, one may use the contralateral artery as inflow, after a small retroperitoneal exposure, to perform a crossover iliofemoral (CIF) bypass grafting procedure, through the Retzius space. Our 10-year experience with CIF bypass grafting in a select group of patients was studied.

METHODS

Between 1986 and 1996, 36 patients underwent CIF bypass grafting for symptomatic unilateral iliac occlusion or stenosis. All patients were examined by means of Doppler ultrasound scanning and underwent bilateral multiplane angiography. Patients were considered for this procedure when the ipsilateral common iliac artery was occluded from its origin or was diffusely and heavily calcified. The decision to perform a CIF bypass grafting procedure was made when no significant disease of the contralateral common iliac artery was seen, and patients who had features of contralateral iliac disease were excluded. The main outcomes were perioperative mortality and morbidity, long-term primary and secondary patency rates, and limb salvage rate.

RESULTS

The study included 31 men and five women, with a mean age of 58.8 years. Indications for bypass grafting were disabling claudication (26 of 36 patients, 72%) and limb-threatening ischemia (10 of 26 patients, 28%). Twelve procedures were performed simultaneously: endarterectomy of the recipient common femoral artery (n = 3), femoropopliteal bypass grafting (n = 4, 11.1%), profundoplasty (n = 4, 11%), and right internal carotid endarterectomy (n = 1). New postoperative erectile dysfunction did not develop in any of the patients. The survival rate was 97.3% at 1 year and 68.5% at 5 years. The primary and secondary patency rates were 94% and 100%, respectively, at 1 year and 76.7% and 95%, respectively, at 5 years. The limb salvage rate was 100% at 1 year and 87% at 3 years.

CONCLUSION

The operative mortality associated with CIF is low. The long-term primary and secondary patency rates are satisfactory, and they are lower than those reported for aortobifemoral bypass grafting. This procedure does not preclude a later performance of an aortobifemoral bypass grafting procedure. CIF bypass grafting is not only suitable for poor-risk patients with a limited life expectancy who have the appropriate arterial anatomy, but also may be warranted for young patients in whom erectile dysfunction is feared.

IFN-gamma and CD8+ T cells restore host defenses against Pneumocystis carinii in mice depleted of CD4+ T cells

Host defenses against infection are profoundly compromised in HIV-infected hosts due to progressive depletion of CD4+ T lymphocytes and defective cell-mediated immunity. Although recent advances in antiretroviral therapy can dramatically lower HIV viral load, blood CD4+ T lymphocytes are not restored to normal levels. Therefore, we investigated mechanisms of host defense other than those involving CD4+ T lymphocytes against a common HIV-related opportunistic infection, Pneumocystis carinii (PC) pneumonia. Using CD4-depleted mice, which are permissive for chronic PC infection, we show that up-regulation of murine IFN-gamma by gene transfer into the lung tissue results in clearance of PC from the lungs in the absence of CD4+ lymphocytes. This resolution of infection was associated with a >4-fold increase in recruited CD8+ T lymphocytes and NK cells into the lungs. The role of CD8+ T cells as effector cells in this model was further confirmed by a lack of an effect of IFN-gamma gene transfer in scid mice or mice depleted of both CD4+ and CD8+ T cells. Cytokine mRNA analysis revealed that recruited, lung-derived CD8+ T cells had greater expression of IFN-gamma message in animals treated with the IFN-gamma gene. These results indicate that CD8+ T cells are capable of clearing PC pneumonia in the absence of CD4+ T cells and that this host defense function of CD8+ T cells, as well as their cytokine repertoire, can be up-regulated through cytokine gene transfer.

Routine ultrasound screening for abdominal aortic aneurysm among 65- and 75-year-old men in a city of 200,000 inhabitants

Unruptured abdominal aortic aneurysm (AAA) is seldom recognized. Thus it is difficult to know whether the incidence of AAA in the general population is high enough to warrant routine screening at least in men after a certain age. Ultrasound screening studies to evaluate the incidence of AAA have been carried out in several English-speaking and Scandinavian countries. The purpose of this report is to describe the results of a study carried out in Belgium. All 65- and 75-year-old men living in the city of Liege, Belgium, were given the opportunity to undergo a free ultrasound examination. Only 41% of the target population was examined. AAA defined as abdominal aortic diameter of >30 mm was observed in 28 subjects (incidence: 3.8%). Mean abdominal aortic diameter was 34.7 mm. A diameter >29 mm was observed in 33 subjects (incidence 4.5%). Mean abdominal aortic diameter was 30.4 mm. On the basis of epidemiological data collected, a high-risk population for AAA was identified. Arterial hypertension (p < 0.05), previous coronary artery surgery (p < 0.05), and smoking (p < 0.06) were more common in subjects with than without AAA. The overall cost of screening was $18.175. The cost per AAA diagnosed was $551.00.

The use of Newton's rings for characterising ophthalmic lenses

The interference technique of Newton's Rings is widely used for the quality control of optical surfaces because the precision obtained with this method proves to be very satisfactory. The dimensions of the rings permits calculation of the radii of curvature of the analysed surfaces and deformation of the interference pattern can be utilised to calculate other parameters, such as astigmatism. We describe the study of progressive surfaces by means of this technique, whereby the analysis of the various points of the progressive corridor is made, and also include information on the power function for these lenses, as well as the addition and corridor length.