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The manner in which informed consent is obtained varies. The aim of this study is to evaluate the level of knowledge about colonoscopy and comparing 2 methods of obtaining informed consent.A comparative, cross-sectional, observational study was conducted on patients that underwent colonoscopy in a public hospital (Group A) and in a private hospital (Group B). Group A received information verbally from a physician, as well as in the form of printed material, and Group B only received printed material. A telephone survey was carried out one or 2 weeks later.The study included a total of 176 subjects (group A [n=55] and group B [n=121]). As regards education level, 69.88% (n=123) of the patients had completed university education, 23.29% (n= 41) secondary level, 5.68% (n=10) primary level, and the remaining subjects (n=2) had not completed any level of education. All (100%) of the subjects knew the characteristics of the procedure, and 99.43% were aware of its benefits. A total of 97.7% received information about complications, 93.7% named some of them, and 25% (n=44) remembered major complications. All the subjects received, read, and signed the informed consent statement before the study. There were no differences between the groups with respect to knowledge of the characteristics and benefits of the procedure, or the receipt and reading of the consent form. Group B responded better in relation to complications (P=.0027) and group A had a better recollection of the major complications (P.0001). Group A had a higher number of affirmative answers (P.0001).The combination of verbal and written information provides the patient with a more comprehensive level of knowledge about the procedure.

The arylamine N-acetyltransferase (NAT-2) polymorphism causes impaired drug metabolism in about half of the white population. By the combined use of polymerase chain reaction (PCR) and restriction mapping with the endonucleases Fok I and Dde I, we have studied the genetic basis underlying NAT-2 polymorphism in genomic deoxyribonucleic acid from 245 healthy Spaniards. The study of three mutations at the NAT-2 gene locus by PCR analysis (namely, 481T, 590A, and 857A) revealed that all these mutations were present in Spaniards at similar frequencies as described in other white populations, strongly contrasting with genetic differences in the CYP2D6 polymorphism between Spaniards and other white subjects. The frequencies for NAT-2 mutations were different in Spaniards compared with Hispanics. About 12% of the subjects studied were incorrectly genotyped by the PCR test. Further studies involving restriction mapping of PCR products revealed the occurrence of at least five NAT-2 mutations that, alone or combined, were present in eight allelic variants of the NAT-2 gene. The allele frequencies were as follows: wild type, 25.3%; 341C + 481T + 803G, 32.9%; 341C + 481T, 6.3%; 282T + 590A, 24.9%; 282T, 3.5%; 590A, 1.6%; 803G, 4.1%; and 857A, 1.4%. The prevalence of the poor acetylator genotype among Spaniards is 53%. Clinical Pharmacology and Therapeutics (1994) 56, 202–209; doi:10.1038/clpt.1994.124

The association between the polymorphism of the cytochrome P450 debrisoquin hydroxylase (CYP2D6) and lung cancer is controversial. Previous reports suggested a link between CYP2D6 phenotype and lung cancer, with poor metabolizers having reduced susceptibility. Nevertheless, negative findings have also been published. By using allele-specific amplification, we have studied the frequency of four CYP2D6 (wild type and mutant) alleles in 89 patients with histologically proved bronchogenic carcinoma and in 98 healthy volunteers. Our findings confirm that poor metabolizers are underpresented among patients with lung cancer because of a different genetic background. Our findings also reveal that the rare CYP2D6(C) mutant allele is sixfold more frequent among patients with lung cancer (p < 0.0005). This suggests that the CYP2D6(C) allele could be considered as an additional risk factor because carriers could have higher susceptibility to the development of lung cancer. Clinical Pharmacology and Therapeutics (1994) 55, 10–14; doi:10.1038/clpt.1994.3

Objective We analyzed in patients with essential tremor (ET) the Thr105Ile polymorphism of the Histamine N-methyltransferase (HNMT) enzyme that is associated to Parkinson’s disease (PD) risk. Methods Leukocytary DNA from 204 ET patients and a control group of 295 unrelated healthy individuals was studied for the nonsynonymous HNMT Thr105Ile polymorphism by using amplification-restriction analyses. Results Patients with ET showed a higher frequency of homozygous HNMT 105Thr genotypes leading to high metabolic activity (p < 0.015) with a statistically significant gene-dose effect, as compared to healthy subjects. These findings were independent of gender, and of tremor localization, but the association of the HNMT polymorphism is more prominent among patients with late-onset ET (p < 0.007). Conclusion These results, combined with previous findings indicating alterations in the frequency for the HNMT Thr105Ile polymorphism in patients with PD, suggest that alterations of histamine homeostasis in the SNC are associated with the risk of movement disorders.

Salivary gland tumours are an important part of the Oral and Maxillofacial Pathology, unfortunately, only few studies on these tumours have been done in Latin-American population. The aim of this study was to compare demographic data on salivary gland tumours in a Mexican sample with those previously published from Latin American and non-Latin American countries. All cases of salivary gland tumours or lesions diagnosed in our service were reviewed. Of the reviewed cases,67 were confirmed as salivary gland tumours. Out of these 64.2% were benign neoplasms, 35.8% were malignant and a slight female predominance (56.7%) was found. The most common location was palate followed by lips and floor of the mouth. Mean age for benign tumours was 40.6 years with female predominance (60.5%). Mean age for malignant tumours was 41 years and female predominance was found again. Palate followed by retromolar area were the usual locations. Pleomorphic adenoma (58.2%), mucoepidermoid carcinoma (17.9%) and adenoid cystic carcinoma (11.9%) were the more frequent neoplasms. All retromolar cases were malignant and all submandibular gland tumours were benign. We found a high proportion of salivary gland neoplasms in children. Our results showed that differences of the studied tumours among our sample and previously reported series exist. These differences can be related to race and geographical location.

The cytochrome P450 CYP2D6 is a polymorphic drug-metabolizing enzyme that is involved in the metabolism of several drugs and xenobiotics. Several independent studies indicate that the CYP2D6 metabolic status is a secondary factor in the risk of developing lung cancer, with individuals with high activity being at increased risk. The occurrence of functionally active duplications of the CYP2D6 gene is a phenomenon that affects 3-8% of Caucasians and up to 30% in some ethnic groups. These duplications cause ultrarapid metabolism of CYP2D6 substrates. In order to establish whether the highest CYP2D6 enzyme activity is associated with an increased risk of cancer, we analyzed the frequency of CYP2D6 gene duplications and enzyme-inactivating mutations in 199 Caucasian patients with lung or larynx cancer and in 335 healthy controls. A significantly increased frequency of carriers of the CYP2D6 gene duplication were found among lung and larynx cancer patients (13%), as compared with healthy controls (6.9%; p0.02). The frequency of the mutated active CYP2D6*9 allele was increased in lung cancer patients (p0.01) but not in larynx cancer patients. Global findings indicate that over 20% patients with lung or larynx cancer show CYP2D6 genotypes leading to ultrarapid metabolism or to the expression of an enzyme with altered kinetics (p0.01 vs. healthy controls). This may influence the metabolism of CYP2D6 substrates, including antineoplastic drugs and opioid derivatives used for pain relief in cancer patients. These patients would require higher doses than those considered as standard. We conclude that dosages for CYP2D6 substrates should be adapted to lung and larynx cancer patients.

Endocarditis related to pacemaker lead is a rare complication of permanent transvenous pacing, of which the diagnosis is carried out with the presence of verrucae in echocardiography and positive blood cultures, its treatment being mixed -medical and surgical- because the isolated medical treatment is rarely successful and the lead should be extracted. We present the case of recurrent endocarditis of several years of evolution, in the which it was not possible to extract of the electrode due to the special characteristics of the patiente (epicardial lead perforating into right atrial).

Reports about the frequency of odontogenic tumors are scarce, and diagnostic criteria used in the reports are not uniform. This article presents the results of a retrospective study of odontogenic tumors recorded in four services of diagnostic pathology in Mexico City (two dental schools, one cancer hospital, and one private oral pathology service). The final diagnosis in each case was based on the 1992 histologic criteria of the World Health Organization. The frequency of odontogenic tumors, expressed as a percent of all oral and maxillofacial specimens, ranged from 0.8% in the cancer hospital (0.02% of all biopsies) to 3.7% in the private oral pathology service. The frequency was identical for the two dental schools (2.5%). We found a total of 349 odontogenic tumors; of these, 345 were benign (98.8%), and 4 (1.1%) were malignant (3 were primary intraosseous carcinomas and 1 was a malignant ameloblastoma). The most frequently occurring tumors were odontoma (34.6%), ameloblastoma (23.7%), myxoma (17.7%), adenomatoid odontogenic tumor (7.1%), and calcifying odontogenic cyst (6.8%). Although relatively rare, odontogenic tumors are still an important cause of extensive surgical procedures in Mexico.

The debrisoquin hydroxylation polymorphism is an autosomic recessive trait of the cytochrome P450IID6, an enzyme involved in drug metabolism, that affects 5% to 10% of white subjects. The genetic basis of this polymorphism was studied in 258 unrelated Spanish white subjects. The results revealed that about 5% of the subjects were homozygous for mutant alleles and that about 1% of the subjects carried alleles that suggested CYP2D6 gene duplication. The extensive metabolizers who were homozygous for the wild-type allele had higher metabolic ratio than the heterozygous extensive metabolizers, indicating a gene-dose effect for the wild type allele. The CYP2D6 allele frequencies indicate a reduced frequency for the CYP2D6(B) allele and a higher frequency for the wild-type allele compared with other white populations. This is also reflected in an increased frequency of the subjects who were homozygous for the wild-type allele among extensive metabolizers. We conclude that the same CTP2D6 mutations are present in Spaniards and other white subjects. Nevertheless, the frequencies of such mutations are different in our population. This implies that a high number of Spanish subjects may behave differently than other white subjects in the effect of drugs metabolized by the CYP2D6 enzyme. Clinical Pharmacology and Therapeutics (1994) 55, 412–417; doi:10.1038/clpt.1994.50

Two cases of Fibromyxoma with an exophytic appearance, both located in the upper maxilla, with full clinical and histological characteristics, are reported, followed by a bibliographical review on myxomas, with an emphasis on Odontogenic Myxoma.

A retrospective study on the results of 116 permanent ventricular pacemaker implantations performed in the Service of Cardiology of the Hospital Clinico Universitario in Salamanca is reported. In the majority of cases the indication for a pacemaker was a complete atrioventricular block (53 cases). Sixteen cases had a "sick-sinus syndrome". An apparent cardiopathy was not found in 84 percent of the cases. In the group of patients with cardiopathy that of ischemic type was the most common. The technique of endocardiac catheter pacing was employed in all cases. An 18 percent of global complications occurred, but in no case an early electrode displacement was registered. Complications appeared at a later time included erosion of the pacemaker in ten cases, and displacement and/or deinsertion in seven. The mean life for 18 displaced generators was 41.3 months. A sudden equipment malfunction occurred in two cases, and an inhibition by potentials of the pectoralis major muscle in another. Morbidity rate was lower to that of other published series, may be due to the use of modern generators with a progressive reduction of its diameter and weight and more flexible electrodes which allow a better implantation. The mortality rate was zero.

The arylamine N-acetyltransferase (NAT2) is a polymorphic enzyme which is expressed in the liver in a genotype-determined manner. NAT2 is involved in activation and inactivation of carcinogens through N-acetylation. We studied the role of this polymorphism in the development of hepatocellular carcinoma (HCC). One hundred consecutive patients diagnosed for HCC and 258 healthy volunteers were studied for NAT2 genotype. The occurrence of seven enzyme-inactivating and silent point mutations in the coding region of the NAT2 gene was studied by mutation-specific PCR amplification. An excess of subjects homozygous for NAT2 loss of function alleles was observed among patients with HCC (68% vs 53.9% controls). The relationship between the slow acetylator NAT2 genotype and HCC risk is more pronounced in patients lacking serum HBV and HCV markers. The additional determination of alleles of the cytochrome P450 2D6 (CYP2D6) gene in the same subjects confirmed our previous findings that subjects with two active CYP2D6 genes are at increased risk of developing HCC. The genetic polymorphism of NAT2 is a relevant factor in the risk for developing HCC (inverse odds ratio slow vs rapid = 1.8; 95% CI 1.1-3.0). The inverse odds ratio for subjects with two risk genotypes (two defect NAT2 genes and two or more active CYP2D6 genes) is 2.6 (95% CI 1.6-4.4) for all patients with HCC, and 5.6 (95% CI 1.4-33.3) for patients without serum viral markers.