Training in Skull Base Endonasal Endoscopic Surgery: Development and Validation of a Novel Low-Cost Simulation with Animal Cadaveric Model

BACKGROUND

Endoscopic skull base surgery is constantly evolving and its scope has expanded. The acquisition of surgical skills involves a long learning curve with significant risks for the patient. Therefore, training in the laboratory has become essential to achieve appropriate proficiency and reduce the morbidity and mortality associated with these procedures. The objective of our work is to develop and validate a cost-effective and easily replicable simulator for endonasal endoscopy training using a swine cadaveric model.

METHODS

We used fresh Pietrain swine heads. Training exercises of increasing complexity were performed. A Specific Technical Skills and Knowledge Scale was created considering the objectives to be assessed in each task. After the simulation, the trainees were required to answer a satisfaction survey.

RESULTS

Ten participants were recruited (5 neurosurgery residents and 5 neurosurgeons). The simulator assessment showed statistically significant differences between groups. Performance was better among the group with endoscopic surgery experience. Face validity was assessed through a postsimulation questionnaire showing an overall mean score of 28.7 out of 30, indicating a highly positive overall assessment of the simulator. Furthermore, 100% of the trainees believe that including endoscopy training in their education would be beneficial.

CONCLUSIONS

The endonasal endoscopy training simulator using a swine cadaveric model is a useful and accessible tool for enhancing surgical skills in this field. It provides an opportunity for training outside the operating room, reducing the potential risks associated with patient practice, and improving the training of residents.

Peritonealized urachal remnant and obstructive congenital peritoneal band. A case report

INTRODUCTION

Intestinal obstruction as a result of congenital peritoneal bands is rare in surgical practice. It typically compromises the small bowel, and it also has been reported to involve the appendix or a Meckel's diverticulum. However, peritonealized urachal remnant as part of a congenital band is highly infrequent.

CASE REPORT

5-year-old boy presenting with intestinal obstruction related to a peritoneal band from the mesentery to the appendix and a peritonealized urachal remnant, associated with an incidental finding of a Meckel's diverticulum. Diagnosis was achieved laparoscopically. The peritoneal band, the urachal remnant, and the Meckel's diverticulum were resected.

DISCUSSION

Kerkeni's congenital band classification consists of 4 independent groups. This case combines both a band stemming from an embryological remnant and an idiopathic band.

The Chilean socio-ethno-genomic cline

Studies of the current Chilean population performed using classical genetic markers have established that the Chilean population originated primarily from the admixture of European people, particularly Spaniards, and Amerindians. A socioeconomic-ethno-genetic cline was established soon after the conquest. Spaniards born in Spain or Chile occupied the highest Socioeconomic Strata, while Amerindians belonged to the lowest. The intermediate strata consisted of people with different degrees of ethnic admixture; the larger the European admixture, the higher the Socioeconomic Level. The present study of molecular genomic markers sought to calculate the percentage of Amerindian admixture and revealed a finer distribution of this cline, as well as differences between two Amerindian groups: Aymara and Mapuche. The use of two socioeconomic classifications - Class and Socioeconomic Level - reveals important differences. Furthermore, Self-reported Ethnicity (self-assignment to an ethnic group) and Self-reported Ancestry (self-recognition of Amerindian ancestors) show variations and differing relationships between socioeconomic classifications and genomic Amerindian Admixture. These data constitute a valuable input for the formulation of public healthcare policy and show that the notions of Ethnicity, Socioeconomic Strata and Class should always be a consideration in policy development.

Efficacy and safety of withholding antimicrobial treatment in children with cancer, fever and neutropenia, with a demonstrated viral respiratory infection: a randomized clinical trial

OBJECTIVES

To determine efficacy and safety of withholding antimicrobials in children with cancer, fever and neutropenia (FN) with a demonstrated respiratory viral infection.

METHODS

Prospective, multicentre, randomized study in children presenting with FN at five hospitals in Santiago, Chile, evaluated at admission for diagnosis of bacterial and viral pathogens including PCR-microarray for 17 respiratory viruses. Children positive for a respiratory virus, negative for a bacterial pathogen and with a favourable evolution after 48 h of antimicrobial therapy were randomized to either maintain or withhold antimicrobials. Primary endpoint was percentage of episodes with uneventful resolution. Secondary endpoints were days of fever/hospitalization, bacterial infection, sepsis, admission to paediatric intensive care unit (PICU) and death.

RESULTS

A total of 319 of 951 children with FN episodes recruited between July 2012 and December 2015 had a respiratory virus as a unique identified microorganism, of which 176 were randomized, 92 to maintain antimicrobials and 84 to withdraw. Median duration of antimicrobial use was 7 days (range 7-9 days) versus 3 days (range 3-4 days), with similar frequency of uneventful resolution (89/92 (97%) and 80/84 (95%), respectively, not significant; OR 1.48; 95% CI 0.32-6.83, p 0.61), and similar number of days of fever (2 versus 1), days of hospitalization (6 versus 6) and bacterial infections throughout the episode (2%-1%), with one case of sepsis requiring admission to PICU in the group that maintained antimicrobials, without any deaths.

CONCLUSIONS

The reduction of antimicrobials in children with FN and respiratory viral infections, based on clinical and microbiological/molecular diagnostic criteria, should favour the adoption of evidence-based management strategies in this population.

Delayed graft function and cotrimoxazole

Acute interstitial nephritis is an infrequent cause of early allograft dysfunction. Prophylactic trimethoprim sulfamethoxazole (cotrimoxazole) is frequently prescribed early in the course of kidney transplantation. Herein we have reported a case of delayed graft function associated with eosinophilia in which the renal biopsy showed interstitial mononuclear infiltrates with abundant eosinophils. An initial methylprednisolone course failed to lower the serum creatinine, but renal function and eosinophilia persistently improved following cotrimoxazole withdrawal and a second course of steroids. Cotrimoxazole acute interstitial nephritis is an infrequent but treatable cause of kidney allograft dysfunction, which should be included in the differential diagnosis of delayed renal allograft function.

Assessment of medical occupational radiation doses in Costa Rica

Participation of the University of Costa Rica (UCR) in activities in an IAEA Regional Project RLA/9/066 through training, equipment and expert missions, has enabled to setting up of a national personal monitoring laboratory. Since 2007, the UCR has been in charge of monitoring around 1800 medical radiation workers of the Social Security System. Individual external doses are measured with thermoluminescent dosemeter using a Harshaw 6600 Plus reader. The service has accreditation with ISO/IEC 17025:2005. Distribution of monitored medical personnel is as follows: 83 % in diagnostic radiology, 6 % in nuclear medicine and 6 % in radiotherapy. Preliminary values for the 75 percentile of annual H(p)(10) in mSv are: radiology 0.37; interventional radiology 0.41; radiotherapy 0.53 and nuclear medicine 1.55. The service provided by the UCR in a steady and reliable way can help to implement actions to limit the doses received by the medical workers and optimise their radiation protection programs.

CTG repeats at the myotonic protein kinase gene in a healthy Chilean population sample

OBJECTIVES

To study the variability at the myotonic dystrophy protein kinase (DMPK) gene in a Chilean sample of healthy people. DM1 is an autosomal dominant disorder caused by an expansion of a (CTG) repeat at the 3'-UTR of the gene DMPK. Healthy individuals have alleles under 35 repeats and diseased individuals have over 50.

METHODS

Genotyping the number of (CTG) repeats at this gene in a sample of healthy Chilean people.

RESULTS

Allele frequencies were significantly different from those of other populations. The most frequent allele was with five repeats. The frequency of larger alleles (>18 CTG repeats) was 11%, close to the European frequency (12%) and higher than the Japanese (8%) and Aboriginal Pehuenche samples (8%).

CONCLUSIONS

Allelic frequencies in the Chilean sample studied were intermediate between those of the two ancestral populations (European and Pehuenche).

Genetic variants in the enhancer region of the thymidylate synthase gene in the Chilean population

AIMS

Thymidylate synthase (TYMS) is an important target enzyme for the fluoropyrimidines. The TYMS gene enhancer region possesses tandemly repeated (TSER) sequences that are polymorphic in humans and different among ethnic groups. The aims of this study were to estimate the frequencies of the TSER variants in two hospital samples located in the northern (HSJ) and eastern (CLC) parts of Santiago, Chile, and compare them with the frequencies in other populations of different ethnic origin.

METHODS

Genotyping of TSER variants in 368 Chilean subjects (HSJ = 178 and CLC = 190) by polymerase chain reaction; products of amplification were electrophoresed, obtaining fragments of 250 bp for allele TSER*3 and 220 bp for allele TSER*2.

RESULTS

The two hospital samples had different degrees of Amerindian admixture (HSJ 34.5%; CLC 15.9%), which was not reflected in the observed frequencies of the CLC TSER*3: 56.8% and HSJ TSER*3: 53.4%.

CONCLUSIONS

Our results are unexpected, considering that genetic markers in the Chilean population generally show allele frequencies between those observed in European Caucasians and Amerindians and that the percentage of Amerindian admixture in CLC is lower than in HSJ. Both hospitals should have had greater frequencies of TSER*3 than were found and the frequency should have been greater in HSJ than in CLC; the only logical explanation of our results is that the frequency of this allele in aboriginal Chilean people is much lower than the 80% estimated for Mongoloid populations.

DYS19 and DYS199 loci in a Chilean population of mixed ancestry

The current Chilean population originated from admixture between aboriginal populations (Amerindians) and Spanish conquerors of European origin. Consequently, the unions that gave rise to the Chilean population were chiefly between Spanish males and aboriginal females, and not the converse. To test the hypothesis that the Y chromosome of the Chilean population is mainly of Spanish origin, while the other chromosomes are from mixed (European and aboriginal) origin, we studied the DYS19 and DYS199 loci in two samples. One sample was obtained from a high socioeconomic stratum, while a second sample was from a low stratum. We studied male blood donors (N = 187) from Santiago, the capital of the country. Subjects were typed for the autosomal ABO and Rh (locus D) blood groups, and for the Y-linked DYS19 and the DYS199 loci, reported as Y-chromosome haplotypes. The aboriginal admixture was estimated for each genetic marker. The percentage of aboriginal admixture was 38.17% for the ABO system and 31.28% for the Rh system in the low socioeconomic stratum and 19.22% and 22.5%, respectively, in the high stratum. Y-chromosome haplotype frequencies constructed from the DYS19 and DYS199 loci demonstrated that the main haplotypes were DYS19*14/DYS199 C, as is often the case with many European populations, and DYS19*13/DYS199 C. The aboriginal admixture from Y-haplotype frequencies was estimated to be 15.83% in the low socioeconomic stratum and 6.91% in the high stratum. These values are lower than the values found using autosomal genetic markers, and are consistent with the historical background of the population studied. This study highlights the population genetic consequences of the asymmetric pattern of genome admixture between two ancestral populations (European and Amerindian).

Genetic Variants of the Paraoxonases ( PON1 and PON2 ) in the Chilean Population

We estimated the frequencies of PON1 and PON2 variants (linked genes) in two hospital samples taken from the northern (San José Hospital, SJH) and eastern (Clínica Las Condes, CLC) parts of Santiago, Chile, using the polymerase chain reaction followed by restriction endonuclease digestion. The two hospital samples have different degrees of Amerindian admixture (SJH, 34.5%; CLC, 15.9%), which is reflected in the observed frequencies of the PON1 *B allele (SJH, 43.1%; CLC, 33.7%) and the PON2*S allele (SJH, 86.3%; CLC, 77.6%); both allele frequencies are significantly different between samples. The frequencies of the combined PON1-PON2 genotypes *A/*B-*C/*C, *A/*B-*S/*S, and *B/*B-*S/*S and of the haplotypes PON*A,C and PON*B,S were significantly different between the SJH and CLC groups. None of the genotype frequencies deviated significantly from those predicted by the Hardy-Weinberg equation. No linkage disequilibrium was found between the PON1 alleles and any of the PON2 alleles in either group (all p > 0.05). In our samples 38.52% (SJH) and 26.25% (CLC) of chromosomes must have the haplotype PON*B,S, presumed to be related to the risk of coronary artery disease. Twenty-four of 193 (12.4%) SJH individuals and 7 of 122 (5.7%) CLC individuals were homozygotes for this haplotype. Finally, our data indicate ethnic-group-dependent genetic differences in the vulnerability to toxic organophosphorus.

Genetic variants of serum butyrylcholinesterase in Chilean Mapuche Indians

We estimated the frequencies of serum butyrylcholinesterase (BChE) alleles in three tribes of Mapuche Indians from southern Chile, using enzymatic methods, and we estimated the frequency of allele BCHE*K in one tribe using primer reduced restriction analysis (PCR-PIRA). The three tribes have different degrees of European admixture, which is reflected in the observed frequencies of the atypical allele BCHE*A: 1.11% in Huilliches, 0.89% in Cuncos, and 0% in Pehuenches. This result is evidence in favor of the hypothesis that BCHE*A is absent in native Amerindians. The frequencies of BCHE*F were higher than in most reported studies (3.89%, 5.78%, and 4.41%, respectively). These results are probably due to an overestimation of the frequency of allele BCHE*F, since none of the 20 BCHE UF individuals (by the enzymatic test) individuals analyzed showed either of the two DNA base substitutions associated with this allele. Although enzymatic methods rarely detect the presence of allele BCHE*K, PCR-PIRA found the allele in an appreciable frequency (5.76%), although lower than that found in other ethnic groups. Since observed frequencies of unusual alleles correspond to estimated percentages of European admixture, it is likely that none of these unusual alleles were present in Mapuche Indians before the arrival of Europeans.

Frequency of the hypervariable DNA loci D18S849, D3S1744, D12S1090 and D1S80 in a mixed ancestry population of Chilean blood donors

Blood donors (N = 150) at San José Hospital (Santiago, Chile) were typed for one VNTR locus (D1S80) and three STR loci (D18S849, D3S1744, D12S1090). A questionnaire was used to determine the socioeconomic level of the donors, because it is known that some genetic markers (e.g., the ABO and Rh groups) are differentially distributed between different socioeconomic strata. This methodology revealed that two of the three socioeconomic strata distinguishable in Santiago were present in our sample of blood donors, with stratum II representing the middle strata and stratum III the low strata. Allele frequency was determined for each locus and socioeconomic stratum, and it was found that the allele distributions of each locus in socioeconomic strata II and III were statistically similar. All loci conformed to the Hardy-Weinberg law and there was no evidence for association between the alleles of the four loci, allelic frequencies being similar to those found in North American Hispanic populations. The results support the view that the analysis of these loci may have useful applications in population genetics as well as in identity tests.

[Genetic composition of Chilean population: rural communities of Elqui, Limari and Choapa valleys]

BACKGROUND

The population that inhabits the semiarid Northern zone of Chile arose from ethnic admixture between aborigines, Spanish conquerors and the influx, during the XVII century, of foreign aboriginal workers and a minority of African slaves.

AIM

To study the phenotypic frequencies of 15 genetic markers among populations inhabiting valleys in the Northern zone of Chile and to estimate the percentage of indigenous, African and Caucasian admixture in these populations.

MATERIAL AND METHODS

Throughout five different field works, blood samples were obtained from 120 individuals living in the Elqui valley, 120 individuals living in the Limari valley and 85 living in the Choapa valley. Blood groups, erythrocyte enzymes, plasma proteins and HLA markers were typified.

RESULTS

In the populations studied, the contribution of non indigenous genes was low in relation with the time elapsed since the Spanish invasion. The Hardy-Weinberg disequilibrium for MNS system would have microevolutive implications. The admixture percentages in these valleys confirm ethnic and historic information. The variation of the enzyme esterase D is identical to that of other Chilean populations.

CONCLUSIONS

The phenotypic and genetic frequencies in the three populations studied and different admixture of indigenous genes is inversely proportional to the geographic distance from Santiago, in Central Chile.

[Paternity analysis using four DNA markers amplified by polymerase chain reaction]

BACKGROUND

DNA typing in forensic analysis is a useful tool to analyze paternity due to its high discrimination power.

AIM

To report the experience of Servicio Medico Legal in Santiago, resolving cases of dubious paternity.

SUBJECTS AND METHODS

Four highly polymorphic loci, amplified by polymerase chain reactions, were analyzed in 153 cases of uncertain paternity. The paternity index was calculated for each case.

RESULTS

The four genetic markers analyzed provided an exclusion probability of 0.933 for the general population in Santiago. Thirty-seven cases were excluded as parents. In 31 cases, the paternity index ranged from 19 to 100, considered as probable paternity and 77 cases had an index of over 100, considered as almost certain paternity. Eight cases had an index between 0.5 and 19, considered as inconclusive. All loci met Hardy-Weinberg expectations and their frequencies were similar to other data from people living in Santiago.

CONCLUSIONS

The use of these genetic markers proved to be very useful, reliable and with a high exclusion power for paternity analysis.

Interaction between ABO and haptoglobin systems in a Chilean population of mixed ancestry

In order to investigate the association between ABO blood groups and serum haptoglobin (Hp), we typed Hp and ABO blood groups in 288 children, who were selected at random among those who began their primary school in 1973 in the Northern Metropolitan area of Santiago, Chile. This region has an Amerindian component of 40% and a Caucasian component (principally Spanish) of 60%. Our results are in contrast with previous studies which have reported that Hp*1 varied among ABO groups in the following manner, O < A < B < AB, and where Hp*1 was significantly lower in group O individuals. In the present study, the order was A < O » B < AB. We found more A and less O individuals with allele Hp*2 and genotype Hp 2-2, and more Hp*1 among O individuals.

[Microsurgical approach and graft anastomosis to the trunk of the facial nerve in the Wistar rat]

An experimental model was developed for the purpose of investigating neural regeneration of the facial nerve in Wistar rats. The anatomic references used to locate the facial nerve at its exit from the skull base are described. A detailed description of the microsurgical anastomosis of cryopreserved nerve allografts is given. The major advantages and disadvantages of rat models compared with other animal models for experimental studies of the facial nerve are discussed.

[Gastric cancer: a unique etiological entity?]

Based on epidemiological, clinical and pathological data, the existence of two etiologic entities, for what is generically considered as gastric carcinoma, is postulated. Environmental factors would be more important in the etiology of the differentiated type of gastric cancer and genetic factors would have a relevant role in the etiology of the undifferentiated type. Geographic, ethnic, environmental and genetic factors participate in the epidemiology of gastric cancer. This review emphasizes the evidences supporting the role of genetic factors in the etiology of undifferentiated gastric cancer. The importance of looking for a shared phenotype among patients with this type of cancer is underscored.

[Infection by intestinal protozoa and helminths in schoolchildren from riverside sectors, with different fecal contamination levels, of Valdivia River, Chile]

During 1993, the prevalences of infection by intestinal protozoa and helminths (IPH) in the riverside schoolchildren population of two sectors of Valdivia river, with different levels of fecal contamination, were compared in relation to their contact with river water (swimming, bathing) and basic sanitation elements (BSE) of their houses: feces and garbage disposal, and water supply. Populations of children from sectors A (n = 418), with significatively greater (SG) total coliform most probable number (MPN), and sector B (n = 400), were examined. PAFS test was used for the stool examination of one sample, from each child. The global prevalence of infection by IPH was similar in A (74.8%) and B (72.5%) sectors. From 10 identified IPH, only Entamoeba histolytica and Hymenolepis nana showed prevalences of infection SG in sector A, than in sector B. The contact of the children with the water of the river showed association with SG prevalences for E. histolytica, Entamoeba coli and Endolimax nana in sector B and for E. histolytica in sector A. No sanitary condition for the different BSE contributed to SG prevalences for E. histolytica, Ascaris lumbricoides and Trichuris trichiura in both sectors, and for E. coli in sector B. The contact with the river water and the different BSE contributed to prevalences SG in 5 and 3 IPH in sectors B and A, respectively. The results suggest that a project in study for the development of a treatment plant of wastewater in sector A, could contribute to control infection by IPH. But, this measure must be associated with improvement of the BSE, health education, and application of chemotherapy measures for geohelminthosis in both sectors.

Serum butyrylcholinesterase (CHE1) polymorphism in a Chilean population of mixed ancestry

We estimated the allele frequencies of three variants of serum butyryl-cholinesterase, CHE1*U, CHE1*A and CHE1*F in an urban population of Santiago, Chile, resulting from a mixture of Amerindians with Europeans (mostly Spanish). The CHE1*A frequency was approximately that expected for this population but the incidence of CHE1*F was higher than previous studies would have predicted, probably because in this case more precise techniques were used for its detection. The finding of a CHE1 AK individual suggests that allele CHE1*K is also present at an appreciable frequency in this population.

[Serum butyrylcholinesterase variants in eastern Santiago population]

BACKGROUND

Succinylcholine causes prolonged apneas in a proportion if subjects that have genetical defect of butyrylcholinesterase, due to the presence of unusual alleles in the locus BCHE.

AIM

To estimate allele frequencies of three variants of serum butyrylcholinesterase, BCHE*U, BCHE*A and BCHE*F in an urban population of Santiago, Chile.

SUBJECTS AND METHODS

Different phenotypes for the locus BCHE were determined in 300 blood samples coming from patients of a private clinical laboratory. The population was formed by an admixture of Amerindian and European (mostly Spanish) people.

RESULTS

The frequency of BCHE*A was similar to that expected for this population, but BCHE*F frequency was greater than predicted. Eight subjects had the genotype BCHE AK.

CONCLUSIONS

The higher frequency found for BCHE*F is probably due to the use of more precise detection techniques. Although the used method cannot distinguish BCHE UK from BCHE UU, the finding of individuals with BCHE AK, must lead to the suspicion that the frequency of the allele BCHE K is not negligible in Santiago.

[Serum levels of prealbumin in undernourished children and controls with or without associated clinical infection]

Due to its short half life and high tryptophan content, prealbumin has been considered a sensitive indicator of protein and/or energy deficiency. In addition, prealbumin diminishes during the acute phase response elicited by either infection or tissue injury. Serum levels of prealbumin were determined in undernourished children with or without associated clinical infection and in their infected or non-infected controls matched for age, sex, race and socioeconomical conditions. Serum levels of prealbumin were significantly lower in undernourished than in control children without overt infections. On the other hand, the concentrations of serum prealbumin diminished significantly and to similar levels both in undernourished and control children with associated clinical infection as compared with those observed in non infected children belonging to the similar nutritional status. A positive correlation was found between prealbumin level and the Z-scores of weight-for-age, height-for-age and weight-for height in children without associated infections, which disappeared in clinically infected patients. Thus, prealbumin is a marker of undernutrition in the absence of infection and could be an earlier and more sensitive indicator of actual undernutrition caused by the metabolic effects of acute phase cytokines, than the anthropometrical measurements used here.

[Genetic composition of the Chilean population: the population from San Pedro de Atacama]

This work describes the genetic composition of atacameños from San Pedro de Atacama. The results show that a) the contribution of non-indigenous genes is relatively low, in relation to the spanish immigration period. b) the Hardy-Weinberg genetic disequilibrium for MNSs system should have biological implications c) the variant for esterasa D enzyme may be the same found in other chilean populations.

[Genetic composition of Chilean population: the Pehuenches from Trapa-Trapa]

This study describes the genetic composition of Pehuenche indians from Trapa-Trapa. The admixture analysis revealed that this group has conserved most of its pre-Columbian gene pool and therefore, is representative of the indians that lived in Southern Chile before the Spanish conquest. A relatively high frequency of a esterase D variant seems to indicate that this is a Chilean aboriginal population marker. The Chilean Pehuenches are genetically similar to their Argentinean relatives, which is not surprising since this last group crossed the Andes Mountains in historic times.

[Genetic evidence corroborates Negme's hypothesis about the greater mildness of American trypanosomiasis in Chile]

Chagas disease is present in northern and central Chile. Not more than 25% of infected individuals have had a pathologic condition presumably due to Trypanosoma cruzi. The majority of individuals with chronic infectious Chagas disease in Chile are asymptomatic in contrast to what has been observed in other South American countries. Historic and paleopathologic evidences suggest that this particular behavior could be explained by a genetic adaptation of Chilean aborigines to T cruzi. Associations between ethnic admixture, presence of Chagas disease, associated cardiac pathology and 4 blood groups (ABO, MNSs, Rh and Duffy) were investigated among inhabitants of San Pedro de Atacama in northern Chile. Cardiac pathology was determined by positive serologic reactions in individuals with abnormal electrocardiographic findings. Individuals with negative serologic results had a significantly greater aboriginal admixture (88%) compared to those with positive serology (66%). This findings supports the hypothesis of genetic adaptation explaining mildness of Chagas disease in Chile.

[HLA antigens in Chagas cardiomyopathy: new evidence based on a case-control study]

We studied the distribution of HLA, B and C antigens in 73 Chagasic subjects with and without heart disease. Both groups were matched for age, sex, birth place and history of family residence. Thirty two subjects without evidence of Chagasic infection, with and without heart disease and matched for the same variables were also studied. Compared to all other groups, a significant increase in the level of the B40 Cw3 antigen combination was found in Chagasic subjects without evidence of heart disease.

[Phenotypic, genotypic and genic frequencies. Serum pseudocholinesterase in blood donors from Santiago de Chile]

Varying distributions of the different forms of pseudocholinesterase are related to different sensitivities of patients to muscle relaxants. We studied the different alleles of this enzyme in a sample of blood donors at a general hospital in Santiago, Chile. The genic frequency of the A allele was 0.0125, which is similar to that reported for different caucasoid populations.

HLA antigens in cardiomyopathic Chilean chagasics

The distribution of HLA antigens in a sample of 124 Chagas serologically positive Chilean individuals was studied. The sample was subdivided according to the presence or absence of chagasic cardiomyopathy, in order to search for genetic differences associated with this pathological condition. The frequency of antigen B40 in the presence of antigen Cw3 was found to be significantly lower in subjects with cardiomyopathy. We tentatively suggest that the presence of these antigens among noncardiomyopathics is associated with a decreased susceptibility to develop chagasic cardiomyopathy in the Chilean population.

Erythrocyte and HLA antigens of Atacameño Indians

The present study reports the results of erythrocyte antigen typing for the following systems: ABO, MN, Rh, Kell, Duffy, and Diego in roughly 180 Atacameño Indians from the oasis of Toconao, northern Chile. A subsample was tested for variation at the histocompatibility loci A, B, and C. Results agree with previous findings based on smaller samples. Caucasian admixture of the Atacameño from Toconao was estimated to be 0.056 +/- 0.022.