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Background: Hemophilia A is an inherited disorder caused by alterations in factor VIII gene (F8) located on the X-chromosome, the intron 22 inversion being the most common mutation. The rest are predominantly point mutations distributed along this large gene of 26 exons., Aim: To implement a molecular diagnostic test to detect mutations in the F8 gene in Chilean patients with Hemophilia A., Material and Methods: To validate the testing methods, we analyzed samples with intron 22 and intron 1 inversion, and with point mutations previously studied, as well as one subject without Hemophilia. We also studied unrelated Chilean patients with Hemophilia A and their female relatives for carrier testing. Intron 22 and intron 1 inversions were studied by long distance polymerase chain reaction (PCR) and point mutations by sequencing the coding and promoter regions of the F8 gene., Results: The results obtained in all samples used for validation were concordant with those obtained previously. In the Chilean patients, the intron 22 inversion and point mutations previously described were observed. In 6 out of 9 patients with mild Hemophilia A we found the same mutation (Arg2159Cys) in exon 23, which has been described as prevalent in mild Hemophilia A., Conclusions: The analysis of intron 22 and intron 1 inversions, as well as of point mutations in the F8 gene will help us to confirm the diagnosis in patients with severe, moderate and mild Hemophilia A, and also it will allow us to perform carrier testing and to provide better genetic counseling.

Background: Metallo-beta-lactamases (MBL) confer high resistance to carbapenems in Pseudomonas aeruginosa (Psae). They are encoded in mobile elements of different genes (VIM, IMP, SMP, GIM), along with other resistance genes., Aim: To detect the presence of MBL in imipenem resistant Psae strains., Material and Methods: Fifty-nine imipenem resistant Psae strains isolated from January 2004 to August 2005 in a University Clinical Hospital, were included. The presence of MBL was studied by Etest (phenotypic) and genotypic polymerase chain reaction (PCR) methods. To rule out a nosocomial outbreak, MBL positive strains were studied by pulse field gel electrophoresis., Results: The presence of MBL was detected in eleven strains. AH were type VIM and were not clonally related. There was no concordance between phenotypic and genotypic MBL detecting methods. All the strains were also multiresistant., Conclusions: The presence of MBL was detected in 19% of imipenem resistant Psae strains.

Background: The early diagnosis and therapy of congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency can prevent adrenal crises and erroneous gender assignment in affected newborns. To achieve this goal neonatal mass-screening programs have been developed, measuring blood 17 alpha-hydroxyprogesterone (17OHP). In Chile there is no experience with this type of screening., Aim: To develop a method for measuring 17OHP in filter paper blood specimens. To obtain reference ranges and determine neonatal 17OHP threshold levels according to gestational age and birth weight. To analyze factors affecting the cost-efficiency ratio and suggest recommendations for the organization of a neonatal screening program for CAH in Chile., Material and Methods: Nine hundred twenty two newborns were studied. 17OHP was measured using double antibody radioimmunoassay in filter paper blood samples obtained 48 h after birth. Reference ranges were determined according to gestational age and birth weight and a cutoff point of 25 ng/ml was established., Results: Seventeen newborns had 17OHP over the cutoff value. They were assessed by a pediatric endocrinologist and in none of them, CAH was confirmed. Therefore the false positive rate of the determination was 1.8%. Among these newborns with elevated 17OHP, 66% had a birth weight below 1.5 kg and 5.8%, a birth weight between 1.5 and 2.5 kg. The cost per reported result was US $ 1. Timing of the recall was between the 3 and 10 days of life. No newborn missed the follow-up., Discussion: To increase the cost-efficiency ratio of an eventual neonatal screening program, newborns with birth weights below 1.5 kg should be excluded and cutoff points should be defined according to birth weight (Rev Méd Chile 2000; 128: 1113-18).

Immunohistochemical (IH) assessment of nuclear estrogen receptor has been considered an alternative method to conventional biochemical assay. The present work intends to compare specificity and sensitivity of IH and biochemical technique to assess nuclear estrogen receptor in formalin-fixed and paraffin-embedded mammary carcinoma samples. IH positive reaction was defined as 14% or more nuclear staining in 100 cells counted under high magnification (400x). Biochemical assay was considered positive over 10 fmol/mg of protein. 66 cases were collected with a mean age of 55.6 years and a mean tumor size of 25.2 mm. Histologically, 62 cases were ductal carcinomas, 2 lobular carcinomas, and 2 medullary carcinomas. Biochemical assay for estrogen receptor was positive in 35 cases (63%) and IH in 40 cases (71%). The present results show that IH assessment of estrogen receptor is highly specific and sensitive. Estrogen receptor present in non-tumor cells and blood vessels walls may disclose false positive biochemical results and false negative result if the tumor mass is small or there are isolated tumor cells. IH assessment of estrogen receptor can be performed in small samples, including in situ lesions. The method of fast, reliable, and of lower cost, IH may be considered the method of choice in cases with insufficient sample for biochemical assay and/or in tumors containing scant cells.