Propagation failure in discrete reaction-diffusion system based on the butterfly bifurcation.

Reaction-diffusion systems are used in biology, chemistry, and physics to model the interaction of spatially distributed species. Particularly of interest is the spatial replacement of one equilibrium state by another, depicted as traveling waves or fronts. Their profiles and traveling velocity depend on the nonlinearities in the reaction term and on spatial diffusion. If the reaction occurs at regularly spaced points, the velocities also depend on lattice structures and the orientation of the traveling front. Interestingly, there is a wide region of parameters where the speeds become zero and the fronts do not propagate. In this paper, we focus on systems with three stable coexisting equilibrium states that are described by the butterfly bifurcation and study to what extent the three possible 1D traveling fronts suffer from propagation failure. We demonstrate that discreteness of space affects the three fronts differently. Regions of propagation failure add a new layer of complexity to the butterfly diagram. The analysis is extended to planar fronts traveling through different orientations in regular 2D lattices. Both propagation failure and the existence of preferred orientations play a role in the transient and long-time evolution of 2D patterns.

Equilibrium and symmetries of altitudinal magnetic rotors on a circle.

Macroscopic magnets can easily be manipulated and positioned so that interactions between themselves and with external fields induce interesting dynamics and equilibrium configurations. In this work, we use rotating magnets positioned in a line or at the vertices of a regular polygon. The rotation planes of the magnets can be modified at will. The rich structure of stable and unstable configurations is dictated by symmetry and the side of the polygon. We show that both symmetric solutions and their symmetry-breaking bifurcations can be explained with group theory. Our results suggest that the predicted magnetic textures should emerge at any length scale as long as the interaction is polar, and the system is endowed with the same symmetries.

The IVIC syndrome: a new autosomal dominant complex pleiotropic syndrome with radial ray hypoplasia, hearing impairment, external ophthalmoplegia, and thrombocytopenia.

The IVIC syndrome is an autosomal dominant condition affecting mainly the upper limbs. It is described from 19 living members of one family of mostly Caucasoid descent; it came to Venezuela from the Canary Islands 140 years ago. The new mutation appeared six generations ago. It has complete penetrance and wide expressivity for a radial ray defect which may vary from an almost normal thumb to a severely malformed upper limb. When present, the thumb has a long/slender metacarpal and a short distal phalanx, reflected in a typical metacarpophalangeal (MP) pattern profile. Anthropometry reveals delayed growth in the forearms, clavicles, and cranium during adolescence, and permanently in the spine; the maturation of the face, tibiae, and feet is normal. The radial carpal bones are always affected, some being still hypoplastic at advanced ages. Constant palmar dermatoglyphic anomalies are a high a-b ridge count, a distally placed or absent t triradius, and an increased frequency of patterns in the second interdigital area. Extraocular muscles are involved almost always, producing strabismus. Hearing is bilaterally impaired due to a mixed congenital loss, either total or partial. Mild thrombocytopenia and leukocytosis are present before the age of 50 years. There is neither associated ectodermal dysplasia nor heart involvement [except for occasional mild, incomplete right bundle branch block (IRBBB)]; imperforate anus occurs in about 10% of affected persons. The possible pathogenetic relationship to the thalidomide embryopathy and to the Holt-Oram syndrome, among others, is discussed.

Autosomal recessive ectodermal dysplasia: I. An undescribed dysplasia/malformation syndrome.

We describe 27 individuals of 7 families related to each other with high probability who showed manifestations of ectodermal dysplasia and other anomalies affecting females as severely as males with variable expressivity. All parents were normal. These families were detected in a relatively isolated and inbred population with very small neighbouring communities from a Caribbean Sea island, Margarita Island, in Northeastern Venezuela (Nueva Esparta State). The clinical picture common to all patients could not be classified within the heterogeneous group of known ectodermal dysplasias and the published cases do not resemble our patients. We believe that this condition constitutes a newly recognized autosomal recessive dysplasia/malformation syndrome of ectodermal dysplasia.

The effect of human leptospirosis on the composition and concentration of serum lipids and lipoproteins.

1. Plasma lipids and lipoproteins were studied in 9 male patients during the immune phase of leptospirosis and 4 months later after recovery. 2. Electrophoretic patterns of plasma lipoproteins were characterized by the absence of alpha- and pre-beta lipoprotein bands and the presence of a single broad beta band. The high-density lipoprotein (HDL) fraction ran in the pre-beta position and triglyceride (TG) content was high. Low-density lipoproteins (LDL) moved into three different bands and were rich in TG. Very low-density lipoproteins (VLDLs) migrated normally and their triglyceride content was low. All lipoprotein fractions had low levels of cholesteryl esters. 3. In infected patients, the fractional lecithin:cholesterol acyltransferase (LCAT) rate (%/h) was low, while the molar LCAT rate (mumol 1(-1)h-1 remained unchanged. Both VLDL and LDL cholesterol levels increased while HDL cholesterol decreased. 4. These findings demonstrated that abnormalities in lipoprotein composition are associated with leptospiral liver injury.

Influence of clofibrate on plasma lecithin: cholesterol acyltransferase (LCAT) activity in rats.

Effects of clofibrate on plasma lecithin: cholesterole acyltransferase (LCAT) activity, plasma lipid levels and hepatic cholesterol content were examined in rats with clofibrate treatment for a short period of time. The results show that the administration of the drug for three weeks produces substantial shifts in hepatic cholesterol fractions and induces changes in the plasma LCAT enzyme. It is suggested that clofibrate increases plasma LCAT activity by induction of the enzyme on the microsomal fraction of the hepatic cell and subsequent secretion by the liver. Presumably clofibrate treatment also produces an increase in the rate of hydrolysis of cholesteryl esters in the rat liver.

Some studies on the enzyme lecithin-cholesterol acyl-transferase in rat plasma.

The results presented in this study, which include different physiological and pathological conditions, show: 1--In the rat subjected to bile duct occlusion there is a rapid decrease in the plasma LCAT activity which is followed by an increase in the activity to normal values at a later time. 2--In the rat subjected to interruption of the enterohepatic circulation of bile salts by means of a sequestering agent there is an increase in the plasma LCAT activity. 3--In the rat subjected to a 48 hour fast there is an increase in the plasma LCAT activity. 4--In the rat subjected to a small dietary cholesterol supplement there is an increase in the plasma LCAT activity.

[Multidisciplinary focus on dentinogenesis imperfecta type II. Clinical analysis. Ultrastructural and genetic pathology]. / Enfoque multidisciplinario de la dentinogénesis imperfecta tipo II. Análisis clínico. Patológico ultraestructural y genético.

A review of the more relevant clinical, radiological, histopathological and genetics aspects of Dentinogenesis imperfecta (DI) is presented, together with the description of a family with DI. The complete analysis of the affected and non-affected members showed that the defect can be classified as a DI type II with an autosomal dominant mode of inheritance with complete penetrance and variable expressivity. Also it is necessary to emphasize the importance of a multidisciplinary approach (Pedodontists, Oral Pathologists and geneticists) in the description, diagnosis and treatment of the individuals affected with DI.

Plasma lecithin: cholesterol acyltransferase activity in normal full-term newborn infants.

Plasma lecithin: cholesterol acyltransferase (LCAT) activity was studied in 100 normal full-term newborn infants during the first few days of life. The present study shows that plasma LCAT activity present at birth-though at much lower levels than those in the maternal blood-undergoes a fall after birth followed by a rise. It is also shown that the activity of the plasma LCAT enzyme is not strictly linked to the esterification of plasma-free cholesterol in the first three days after birth. However, from the fourth day onwards, there was a good correlation between LCAT activity and esterification of plasma-free cholesterol. The results suggest that plasma LCAT in newborn infants could be partially derived from maternal sources.

Focal epithelial hyperplasia: human-papillomavirus-induced disease with a genetic predisposition in a Venezuelan family.

A study on the presence of human papillomavirus (HPV) DNA sequences and focal epithelial hyperplasia (FEH) in a family of Venezuelan ancestry has revealed that FEH is an HPV-induced disease presenting familial aggregation. The genealogical evidence indicates a genetic predisposition to the disease.

[Impact of hypertensive disease of pregnancy on intrauterine growth retardation]. / Impacto del sindrome hipertensivo del embarazo en el retardo del crecimiento intrauterino.

BACKGROUND: Intrauterine growth retardation, associated to hypertensive disease of pregnancy, is responsible for a higher perinatal mortality and morbidity. AIM: To assess obstetrical, perinatal and neonatal features of intrauterine growth retardation associated to hypertensive disease of pregnancy. PATIENTS AND METHODS: One hundred thirty seven newborns with intrauterine growth retardation, whose mothers had hypertensive disease of pregnancy, were compared to 165 similar newborns but whose mothers did not have the disease. RESULTS: The incidence of intrauterine growth retardation associated to hypertensive disease of pregnancy was 45.4%. Maternal obesity at the start and end of pregnancy, a pregestational weight over 65 kg and a weight increment of more than 20 kg during pregnancy were risk factors for hypertensive disease of pregnancy with relative risks of 1.76, 1.62, 1.62 and 2.09 respectively. Relative risks for cesarean section and prematurity were also higher among women with hypertensive disease of pregnancy. Intrauterine growth retardation associated to maternal hypertension was symmetrical and severe in 37.9% of newborns. All seven neonatal deaths occurred in newborns with severe retardation. CONCLUSIONS: Neonatal and perinatal morbidity and mortality are higher in newborns with intrauterine growth retardation. Hypertensive disease of pregnancy was associated with a twice higher incidence of asymmetrical intrauterine growth retardation.

Enamel hypoplasia and age at weaning in 19th-century Florence, Italy.

A sample representing a population of the Florence district of middle 19th century was studied to determine the age of occurrence of enamel hypoplasias. The age interval most affected was that between 1.5 and 3.5 years. Historical sources on weaning habits of 19th-century Italian populations indicate a weaning period between 12 and 18 months. This is in agreement with the data on enamel defects, showing that children of post-weaning age are more subject to stress. Wide "grooves", with prolonged duration, are concentrated between 2 and 2.5 years, whereas "lines" occur primarily between 2.5 and 3 years. We suggest that this distribution could reflect the gradual introduction of dietary supplements until weaning is complete.

[Analysis of consanguinity in some populations of the V Region, Valparaiso, Chile, from 1880 to 1969]. / Análisis de la consaguinidad en poblaciones de la V Región, Valparaíso, Chile, de 1880 a 1969.

The population structure of 10 populations ("comunas") in Valparaíso, V Region Chile, was studied through the frequency of consanguineous marriages (%CM) and the coefficient of consanguinity (alpha), in order to know their dynamics, and gather information for clinical and genetic epidemiological studies as well as for isonymy studies. The comunas were grouped according to density: Group I, high density, more than 100 inhabitants/km2; Group II, intermediate, between 25 and 99 inhabitants/km2; and Group III, low, less than 25 inhabitants/km2. Data were obtained from parochial archives and national census, from 1880 to 1969. CM's were divided in: uncle-aunt/nephew-niece (12), first cousins (22), first cousins one removed (23), second cousins (33) and multiple consanguinity (M), and the four subtypes of 12 and 22. Percentage of CM and alpha diminish in time. Groups I and II show similar values, but lower in I, and show a constant decrease. Group III has higher values and considerable fluactuations. Types 12 and 22 contribute mostly to %CM and alpha in the 3 groups. Subtypes of 12 and 22 do not occur at random. This temporary and spatial behavior can be explained because of sociocultural and socioeconomical factors in each group, being density an indicator of endogamy. This behavior is consistent with current coefficients of endogamy obtained by isonymy.

Some variables of the craniofacial complex in a Venezuelan population of Negroid ancestry.

A total of 226 individuals (101 males and 125 females), from La Sabana, a Venezuelan Negroid isolate, with ages between 8 and 60 years, were studied in order to characterize the population for its craniofacial variables and to study the behavior of these variables in relation to age and sex. The variables studied were grouped in three categories: direct cephalometric variables, which included 6 measurements taken directly on the individuals; indirect cephalometric variables, which included 18 measurements (9 angular and 9 linear), taken on lateral head films; and dental variables, which included 9 measurements taken from dental models. In general the direct variables showed the lowest coefficients of variation (CV), suggesting homogeneity within this sample. They were followed by the dental and the indirect variables, which had the highest CV values. In order to detect age and sex effects on the variables, sex and age group comparisons were performed with Student t tests. A greater proportion of significant differences were found among the direct variables, indicating that age and sex have more influence on this group of variables than upon the other two. Comparisons of our sample from La Sabana, with samples from African Negroid, Caucasoid, and Amerindian population show that La Sabana individuals have a craniofacial pattern basically Negroid, as we expected, although some contribution from Caucasoides and especially Amerindians is also suggested in our data.

Estimation of inbreeding by isonymy in Iberoamerican populations: an extension of the method of Crow and Mange.

The method of isonymy for the estimation of inbreeding levels was extended to use the potentialities offered by the Iberoamerican surname system, in which a child inherits his surnames both from the father and the mother. Four possible types of isonymy were recognized between the family names of a husband-wife pair. It was found that, limited to simple consanguinity, the ratio between isonymy and the inbreeding coefficient of consanguineous individuals, starting from first cousins, is constant and equal to 16. Consanguinity levels were studied in four Venezuelan groups, Isla de Toas, Los Teques, Quibor, and Colonia Tovar, using genealogies, classical isonymy, and the extended method. It was found that, for Iberoamerican populations, the extended method is more precise than the classical method.

Comparisons of Lasker's coefficient of relationship in a Venezuelan town in two different periods.

A formula for the standard error of Lasker's coefficient of relationship Ri derived from isonymy is proposed, and used to test for differences in relationship in two groups of pairs of spouses from the town of Quibor in Venezuela sampled one century apart. From analysis of the relationship, it was possible to attribute population growth also to immigration. Further, the study of the values of Ri showed that the surnames belonging to the male line are more frequent and stable in this population, which is characterized by a predominantly agricultural activity. From the analysis of the coefficients of relationship, the population of Quibor is also classified as patrilocal.

PIP: Lasker's coefficient of relationship has been used to measure genetic similarity between and within human populations, and to determine the temporal variation of the similarity. A formula for the standard error of Lasker's coefficient of relations Ri derived from isonomy is proposed, and used to test for differences in relationship in 2 groups of pairs of spouses from the town of Quibor in Venezuela sampled 1 century apart. Members of this studied population each have 2 surnames, differing from traditionally studied populations employing the single surname Northern European system. Quibor's 1980 population totaled 22,100, having grown rapidly from its 1940 inhabitant level of 3100. From analysis of the relationship, it was possible to attribute population growth also to immigration. Further, the study of the values of Ri showed that the surnames belonging to the male line are more frequent and stable in this predominantly agricultural population. From the analysis of the coefficients of relationship, the population of Quibor is also classified as patrilocal.

Torus palatinus: a segregation analysis.

Segregation analysis of 99 sibships in 2 samples from Venezuela and Japan indicates that a torus palatinus is inherited in simple dominant fashion. The gene shows variable expressivity and penetrance close to 85%, without significant heterogeneity between the populations considered. No evidence of sporadic cases has been found.

Population structure of two black Venezuelan populations studied through their mating structure and other related variables.

In order to obtain information about the population structure of two black Venezuelan populations with historical differences both in their origins and development, a variety of variables were utilized, especially on marital structure, including: frequency of surnames, isonymy, population genealogical consanguinity, multiple unions, and marital distances, all of which provided information and isolation, migration, endogamy, consanguinity, and patri-matrifocality. Results showed differences in the extent of isolation and endogamy, as well as differences in population structure, which can be directly related with historical conditions of each population. Results agree with those previously obtained with traditional genetic polymorphisms and with the historical information available. Thus, the usefulness of surnames for inferring about population structure is supported, as well as the usefulness of historical information for explaining genetic diversity.

PIP: "In order to obtain information about the population structure of two black Venezuelan populations with historical differences both in their origins and development, a variety of variables were utilized, especially on marital structure, including: frequency of surnames, isonymy, population genealogical consanguinity, multiple unions, and marital distances, all of which provided information and isolation, migration, endogamy, consanguinity, and patri-matrifocality. Results showed differences in the extent of isolation and endogamy, as well as differences in population structure, which can be directly related with historical conditions of each population." (EXCERPT)

[Amelogenesis imperfecta. Description of a clinical case]. / Amelogénesis imperfecta. Descripción de un caso clínico.

A family of five was examined. Four of them presented with enamel alteration including changes in colour and loss of enamel surface. A genetic study was undertaken which revealed an autosomal dominant inheritance with complete penetration and variable expressivity. This is reflected in shape, number, extension and depth of the affected areas. Amelogénesis Imperfecta type IV was diagnosed using Shields classification.

Inbreeding as measured by isonymy in two Venezuelan populations and its relationship to other variables.

Isonymy is a useful approach to the study of population structure and thus can be utilized to detect deviations from random mating. In this study we give the results of an analysis of inbreeding levels and relate such variables as mean marital distance, surnames repeated in isonymous couples, and percentage of people using only maternal surnames to inbreeding and endogamy in two Venezuelan populations of black ancestry, Birongo and La Sabana. These populations differ in their sociocultural development and degree of isolation. We estimated inbreeding through isonymy and directly from genealogy. The most important findings are that the Ft values are higher than the a's, that the Fn component of Ft is higher than the Fr component, and that there is higher endogamy, inbreeding, and isolation in Birongo than in La Sabana. These results are in agreement with the sociocultural and historical background and development of each population. Nevertheless, both populations show similar temporal trends in almost all the variables analyzed. The use of isonymy as a complementary tool to study population structure is proposed, especially for Ibero-American populations.