Insights into the Y chromosome human diversity in Uruguay

BACKGROUND

With regard to the origin of its population and microevolutionary processes, Uruguay exhibits distinctive features that distinguish it from other countries in Latin America, while at the same time sharing several similarities. In this article, we will focus on the variability of paternal genetic lineages in two geographical regions with different histories that can be considered as examples of distinct populations for the continent. In general terms, the genetic diversity is a result of different demographic processes related to the American conquest and colonisation. These resulted in distinct ancestral components which vary geographical and depend on the distribution by sex within these components. In Uruguay, native maternal haplogroups are significantly more frequent in the North. Although there are several studies about the geneticvariability of Uruguay, little is known about male genetic lineages.

AIMS

The aim of this work is to present an updated study of the male genetic variability of the Uruguayan population.

METHODS

We analyzed 13 biallelic markers and 27 STRs located in the male-specific region of the Y chromosome for 157 males: 98 from the capital, Montevideo, and 59 from Tacuarembó.

RESULTS

Almost all haplogroups found in both locations are European (99% and 93.2% respectively). One Sub-Saharan African haplogroup was found in Montevideo (1%) and 2 in Tacuarembó (3%), while Native haplogroups were found only in Tacuarembó, evidencing a strong sex-biased admixture. By crossing genetic and genealogical information we could relate European haplogroups with different waves and times of migrations.

DISCUSSION

Network analysis indicated a very diverse male population, suggesting that European migrants came from heterogeneous geographic locations and in different waves. Tacuarembó has closer population affinities with Iberian populations while Montevideo is more diverse. Male population expansion expansion, can be explained by the large number of migrants that arrived during the XIX century and the first half of the XX century.

CONCLUSIONS

The Uruguayan male gene pool is the result of several migration waves with diverse origins, with strong sex-biased admixture that can be explained by the European migration, the violence against the indigenous males, and the segregation of the Africansadmixture that can be explained due to European migration, violence against Natives, and segregation against African males.admixture that can be explained due to European migration, violence against Natives, and segregation against African males.admixture that can be explained due to European migration, violence against Natives, and segregation against African males.admixture that can be explained due to European migration, violence against Natives, and segregation of hte Africans.

DNA polymorphisms associated with lactase persistence, self-perceived symptoms of lactose intolerance, milk and dairy consumption, and ancestry, in the Uruguayan population

Uruguay has one of the highest per capita milk intakes worldwide, even with a limited supply of lactose-free products; furthermore, the admixed nature of its population is well known, and various frequencies of lactase persistence (LP) are observed in the source populations. We aimed to contribute to the understanding of the relation between allelic variants associated with LP, milk consumption, digestive symptoms, and genetic ancestry in the Uruguayan population. Samples of saliva or peripheral blood were collected from 190 unrelated individuals from two regions of Uruguay, genotypes for polymorphic sites in a fragment within the LCT enhancer were determined and allelic frequencies calculated in all of them. Data were collected on frequency of milk and dairy consumption and self-reported symptoms in a subsample of 153 individuals. Biparental and maternal ancestry was determined by analyzing individual ancestry markers and mitochondrial DNA. Twenty-nine percentage of individuals reported symptoms attributed to the ingestion of fresh milk, with abdominal pain, bloating and flatulence being the most frequent. European LP-associated allele T-13910 showed a frequency of 33%, while other LP-associated alleles like G-13915 and T-14011 were observed in very low frequencies. Associations between self-reported symptoms, fresh milk intake, and C/T-13910 genotype were statistically significant. No evidence of association between genetic ancestry and C/T-13910 was found, although individuals carrying one T-13910 allele appeared to have more European ancestry. In conclusion, the main polymorphism capable of predicting lactose intolerance in Uruguayans is C/T-13910, although more studies are required to unravel the relation between genotype and lactase activity, especially in heterozygotes.

Filogeografía de mitogenomas indígenas de Uruguay

Recientemente, diversos estudios sobre la población uruguaya han demostrado que está conformada por desiguales aportes de europeos, africanos y pueblos originarios, entre otros. El aporte indígena es mayor cuando se analiza la contribución por línea materna, aunque su origen étnico/geográfico no es claro, ni tampoco cuándo ni cómo llegaron los distintos grupos. Para aportar al conocimiento del poblamiento prehistórico e histórico del territorio y sus relaciones con otras poblaciones se analizan, por secuenciación masiva, 32 genomas mitocondriales completos (mitogenomas) de habitantes actuales del país, identificados previamente por sus regiones hipervariables como correspondientes a los cuatro haplogrupos principales de origen americano. Se determinaron siete nuevos subhaplogrupos (A2be, A2bf, B2an, C1d1h, C1b30, C1b31 y D1x), otro se redenominó (C1d1d - actual C1d1g) y se plantea la revisión de los criterios de asignación de B2b6 y D1g5. Se estimó la antigüedad de los subhaplogrupos nuevos, que varía entre 4554 y 11985 años, con la excepción de C1d1g, cuya edad fue estimada en 20736 años. Algunas secuencias pudieron ser vinculadas a distintos grupos étnicos o a diversas regiones geográficas, como Amazonia, Chaco, Pampa, o Andes. Se discuten las nuevas asignaciones desubhaplogrupos y las de algunos previamente definidos, así como su distribución geográfica y antigüedad, con relación al panorama general de América del Sur.

Differential admixture in Latin American populations and its impact on the study of colorectal cancer

Genome-wide association studies focused on searching genes responsible for several diseases. Admixture mapping studies proposed a more efficient alternative capable of detecting polymorphisms contributing with a small effect on the disease risk. This method focuses on the higher values of linkage disequilibrium in admixed populations. To test this, we analyzed 10 genomic regions previously defined as related with colorectal cancer among nine populations and studied the variation pattern of haplotypic structures and heterozygosity values on seven categories of SNPs. Both analyses showed differences among chromosomal regions and studied populations. Admixed Latin-American samples generally show intermediate values. Heterozygosity of the SNPs grouped in categories varies more in each gene than in each population. African related populations have more blocks per chromosomal region, coherently with their antiquity. In sum, some similarities were found among Latin American populations, but each chromosomal region showed a particular behavior, despite the fact that the study refers to genes and regions related with one particular complex disease. This study strongly suggests the necessity of developing statistical methods to deal with di- or tri-hybrid populations, as well as to carefully analyze the different historic and demographic scenarios, and the different characteristics of particular chromosomal regions and evolutionary forces.

Ancestría genética y estratificación social en Montevideo, Uruguay

Diversos estudios genéticos han demostrado que la población uruguaya es trihíbrida, formada por europeo/mediterráneos, indígenas y africanos, cuyo aporte varía en distintas regiones del país. Pese a que Montevideo es la capital de la República, hay escasos estudios sobre los orígenes de su población, que pueden diferir de otras regiones. En este trabajo se propone indagar sobre estos orígenes a partir de información genética en una muestra derivada de una previamente publicada, profundizando en algunas características para determinar su posible influencia en la estimación de la ancestría. Se consideró una muestra de 269 mujeres (casos y controles de un estudio de cáncer de mama) en quienes se analizaron haplogrupos y secuencias de las regiones hipervariables del ADN mitocondrial (ADNmt) y marcadores individuales de ancestría (AIMs) del ADN nuclear. Se observó que había diferencias en los porcentajesde ancestría cuando se analizaban separadamente las personas que se atendían en el sistema público de salud en relación a las que lo hacían en el sistema mutual, con diferencias significativas para el aporte indígena y el europeo/mediterráneo. Luego de corregidos los valores por lugar de atención de salud, se estimaron los siguientes aportes: 24.6% indígena, 67,7% europeo/mediterráneo y 7,7% africano para herencia materna, y de 11,1% indígena, 81,4% europeo/mediterráneo, y 7,5% africano para la herencia biparental. Se analizaron particularmente los aportes indígena y africano y se discutieron los resultados con relación a otros estudios. Debido a las diferencias encontradas relacionadas con la heterogeneidad de la población montevideana, se alerta sobre el muestreo y valores de referencia para estudios poblacionales futuros.

Genetic Admixture Analysis in the Population of Tacuarembó-Uruguay Using Alu Insertions

Tacuarembó is a department located in northeastern Uruguay, whose population is the result of several migration waves from Europe and Near East, as well as Africans and Afro-descents mostly from Brazil; these waves settled with the territory's various Native ethnic groups (Charrúa, Minuán, and Guaraní). In the past, this population has been the focus of genetic studies showing this trihybrid origin, with greater contributions of Natives and Africans than in other Uruguayan regions. In this study we analyzed eight Alu insertions (A25, ACE, APOA1, B65, D1, F13B, PV92, TPA25) to provide valuable information for ancestrality and genetic differentiation and to compare with both previous studies on the Tacuarembó population and Alu frequencies in other Uruguayan populations. The European contribution to Alu and classical markers was almost equal to that of a previous study using 22 classical markers (63% vs. 65%), while African contribution was higher (30% vs. 15%), and Native American contribution shows an important difference in Alu: 7% versus 20%. We found no significant differences in genetic differentiation between Tacuarembó and Montevideo but significant differences between Tacuarembó and Basque descendants from Trinidad. Our results support previous findings obtained with classical markers that demonstrate the trihybrid composition of the Tacuarembó population, correlated with historical records. Thus, Alu insertions provide interesting information in light of the admixture process in the Uruguayan population.

A South American Prehistoric Mitogenome: Context, Continuity, and the Origin of Haplogroup C1d

Based on mitochondrial DNA (mtDNA), it has been estimated that at least 15 founder haplogroups peopled the Americas. Subhaplogroup C1d3 was defined based on the mitogenome of a living individual from Uruguay that carried a lineage previously identified in hypervariable region I sequences from ancient and modern Uruguayan individuals. When complete mitogenomes were studied, additional substitutions were found in the coding region of the mitochondrial genome. Using a complete ancient mitogenome and three modern mitogenomes, we aim to clarify the ancestral state of subhaplogroup C1d3 and to better understand the peopling of the region of the Río de la Plata basin, as well as of the builders of the mounds from which the ancient individuals were recovered. The ancient mitogenome, belonging to a female dated to 1,610±46 years before present, was identical to the mitogenome of one of the modern individuals. All individuals share the mutations defining subhaplogroup C1d3. We estimated an age of 8,974 (5,748–12,261) years for the most recent common ancestor of C1d3, in agreement with the initial peopling of the geographic region. No individuals belonging to the defined lineage were found outside of Uruguay, which raises questions regarding the mobility of the prehistoric inhabitants of the country. Moreover, the present study shows the continuity of Native lineages over at least 6,000 years.

Effect of genetic ancestry on leukocyte global DNA methylation in cancer patients

BACKGROUND

The study of genetic variants alone is not enough to explain a complex disease like cancer. Alterations in DNA methylation patterns have been associated with different types of tumor. In order to detect markers of susceptibility for the development of cutaneous melanoma and breast cancer in the Uruguayan population, we integrated genetic and epigenetic information of patients and controls.

METHODS

We performed two case-control studies that included 49 individuals with sporadic cutaneous melanoma and 73 unaffected controls, and 179 women with sporadic breast cancer and 209 women controls. We determined the level of global leukocyte DNA methylation using relative quantification of 5mdC by HPLC, and we compared methylation levels between cases and controls with nonparametric statistical tests. Since the Uruguayan population is admixed and both melanoma and breast cancer have very high incidences in Uruguay compared to other populations, we examined whether individual ancestry influences global leucocyte DNA methylation status. We carried out a correlation analysis between the percentage of African, European and Native American individual ancestries, determined using 59 ancestry informative markers, and global DNA methylation in all participants.

RESULTS

We detected global DNA hypomethylation in leukocytes of melanoma and breast cancer patients compared with healthy controls (p < 0.001). Additionally, we found a negative correlation between African ancestry and global DNA methylation in cancer patients (p <0.005).

CONCLUSIONS

These results support the potential use of global DNA methylation as a biomarker for cancer risk. In addition, our findings suggest that the ancestral genome structure generated by the admixture process influences DNA methylation patterns, and underscore the importance of considering genetic ancestry as a modifying factor in epigenetic association studies in admixed populations such as Latino ones.

Breast cancer risk and genetic ancestry: a case-control study in Uruguay

Background

Uruguay exhibits one of the highest rates of breast cancer in Latin America, similar to those of developed nations, the reasons for which are not completely understood. In this study we investigated the effect that ancestral background has on breast cancer susceptibility among Uruguayan women.

Methods

We carried out a case–control study of 328 (164 cases, 164 controls) women enrolled in public hospitals and private clinics across the country. We estimated ancestral proportions using a panel of nuclear and mitochondrial ancestry informative markers (AIMs) and tested their association with breast cancer risk.

Results

Nuclear individual ancestry in cases was (mean ± SD) 9.8 ± 7.6% African, 13.2 ± 10.2% Native American and 77.1 ± 13.1% European, and in controls 9.1 ± 7.5% African, 14.7 ± 11.2% Native American and 76.2 ± 14.2% European. There was no evidence of a difference in nuclear or mitochondrial ancestry between cases and controls. However, European mitochondrial haplogroup H was associated with breast cancer (OR = 2.0; 95% CI 1.1, 3.5).

Conclusions

We have not found evidence that overall genetic ancestry differs between breast cancer patients and controls in Uruguay but we detected an association of the disease with a European mitochondrial lineage, which warrants further investigation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12905-015-0171-8) contains supplementary material, which is available to authorized users.

Questioning the "melting pot": analysis of Alu inserts in three population samples from Uruguay

The way that immigrants integrate into recipient societies has been discussed for decades, mainly from the perspective of the social sciences. Uruguay, as other American countries, received diffferent waves of European immigrants, although the details of the process of assimilation, when it did occur, are unclear. In this study we used genetic markers to understand the process experienced by the Basques, one of the major migration waves that populated Uruguay, and their relation to other immigrants, as well as to Native American and African descendants. For this purpose, we analyzed the allele frequencies of 10 ALU loci (A25, ACE, APOA1, B65, D1, F13B, PV92, TPA25, HS2.43, and HS4.65) in three samples from Uruguay (two of Basque descendants, one of non-Basque descendants) from two locations: Montevideo and Trinidad. No departure from Hardy-Weinberg expectations was observed, with the exceptions of the APOA1 and D1 loci in the non-Basque descendants' samples. Our data show that the major genetic contribution in the three samples comes from Europe (78-88%), with minor African (10-15%) and Native American (0-10%) contributions. Genetic distances reveal that Basque descendants from Trinidad cluster with Europeans, whereas both Montevideo samples cluster together and are separate from other populations, showing two diffferent types of integration, related to the general characteristics of each regional population.

A new mitochondrial C1 lineage from the prehistory of Uruguay: population genocide, ethnocide, and continuity

Uruguayan population has been considered as of European descent, as its Native populations victims of genocide apparently disappeared in the 19th century. Contradicting this national belief, genetic studies have shown a substantial Native contribution. However, the continuity between prehistoric, historic, and present populations remains unproved. With the aim of adding elements to prove a possible population continuity, we studied a mitochondrial lineage, part of haplogroup C1, analyzing the complete genome of a modern Uruguayan individual and the hypervariable region I (HVRI) in prehistoric, historic, and contemporary individuals. Several individuals carried the mutations that characterize this lineage: two from an archaeological mound located in the east of the country, the Charrúa Indian chief Vaimaca Perú and five individuals from the present population. The lineage was initially characterized by its HVRI sequence, having the four typical C1 mutations and adding 16051G and 16288C; other mutations were also found: 16140C was found in all but the oldest individual, dated 1,610 years BP, while 16209C, 16422C, and 16519C were found only in some individuals. Hypervariable region II showed the typical C1 mutations and 194T. The coding region, analyzed in modern individuals, was characterized by 12378T, while other mutations found were not common to all of them. In summary, we have found and described a new lineage that shows continuity from prehistoric mound builders to the present population, through a representative of the extinct Charrúa Indians. The lineage appeared at least 1,600 years ago and is carried by approximately 0.7% of the modern Uruguayan population. The continuity of the lineage supports alternative perspectives about Uruguayan national identity and the meaning of the genocide, best labeled as ethnocide because of its consequences. It also contributes to the discussion about who the prehistoric mound builders were, and to the origin, at least in the maternal line, of a Charrúa Indian. From a more general perspective, we can conclude that the characteristics, evolution, and expansion of founder haplogroup C in America have not yet been elucidated.

Mitochondrial DNA in Basque descendants from the city of Trinidad, Uruguay: Uruguayan- or Basque-like population?

Like other countries in the Americas, during its colonization Uruguay was the recipient of immigrants from several ethnic groups from Europe, as well as of enslaved Africans. After its independence in 1830, Basques were the first group of Europeans to arrive in the country. In this paper, we aim to contribute to the understanding of the process of integration of these migratory waves into the Uruguayan society. For that purpose, individuals of Basque origin from the city of Trinidad, Uruguay, were chosen to participate in this study. Particularly, we wanted to determine if Basque descendants in Uruguay remained relatively isolated or if they mixed with other ethnic groups. Mitochondrial DNA (mtDNA) of 60 self-identified Basque descendants, taken from a larger sample of subjects with Basque ancestors, was analyzed. The origin of mtDNA haplogroups was 77.8% European, 20.4% Amerindian, and 1.8% African, showing similar frequencies to other Uruguayan regions. Very few sequences showed a clear Basque origin, although other sources such as the Canary Islands are likely. Moreover, genetic distances clearly show that Basque descendants are genetically closer to other Uruguayan groups than to European populations, including Basques. It is possible to conclude that Basques and their descendants in the region of Trinidad did not remain isolated and that their marriage behavior was similar to that of other Uruguayan populations. However, to have a more accurate picture of the way Basques intermarried with other populations in Uruguay, new analyses are needed that take into account paternal lineages as well as biparental genetic markers.

Control region variability of haplogroup C1d and the tempo of the peopling of the Americas

Background

Among the founding mitochondrial haplogroups involved in the peopling of the Americas, haplogroup C1d has been viewed as problematic because of its phylogeny and because of the estimates of its antiquity, apparently being much younger than other founding haplogroups. Several recent analyses, based on data from the entire mitochondrial genome, have contributed to an advance in the resolution of these problems. The aim of our analysis is to compare the conclusions drawn from the available HVR-I and HVR-II data for haplogroup C1d with the ones based on whole mitochondrial genomes.

Methodology/Principal Findings

HVR-I and HVR-II sequences defined as belonging to haplogroup C1d by standard criteria were gathered from the literature as well as from population studies carried out in Uruguay. Sequence phylogeny was reconstructed using median-joining networks, geographic distribution of lineages was analyzed and the age of the most recent common ancestor estimated using the ρ-statistic and two different mutation rates. The putative ancestral forms of the haplogroup were found to be more widespread than the derived lineages, and the lineages defined by np 194 were found to be widely distributed and of equivalent age.

Conclusions/Significance

The analysis of control region sequences is found to still harbor great potential in tracing microevolutionary phenomena, especially those found to have occurred in more recent times. Based on the geographic distributions of the alleles of np 7697 and np 194, both discussed as possible basal mutations of the C1d phylogeny, we suggest that both alleles were part of the variability of the haplogroup at the time of its entrance. Moreover, based on the mutation rates of the different sites stated to be diagnostic, it is possible that the anomalies found when analyzing the haplogroup are due to paraphyly.

HLA class I antigen and HLA-A, -B, and -C haplotype frequencies in Uruguayans

HLA class I antigens were determined for 959 unrelated Uruguayans. The predominant HLA alleles were A2, Cw4, and B35, and the most frequently observed two-loci haplotypes were A2-B44 and B35-Cw4. The most frequent three-loci HLA haplotype was A2-Cw5-B44. We compared the Uruguayan sample with similar data from other populations.

Population structure and admixture in Cerro Largo, Uruguay, based on blood markers and mitochondrial DNA polymorphisms

Recent studies of the Uruguayan population revealed different amounts of Amerindian and African genetic contributions. Our previous analysis of Afro-Uruguayans from the capital city of the Department of Cerro Largo showed a high proportion of African genes, and the effects of directional mating involving Amerindian women. In this paper, we extended the analysis to a sample of more than 100 individuals representing a random sample of the population of the whole Department. Based on 18 autosomal markers and one X-linked marker, we estimated 82% European, 8% Amerindian, and 10% African contributions to their ancestry, while from seven mitochondrial DNA site-specific polymorphic markers and sequences of hypervariable segment I, we determined 49% European, 30% Amerindian, and 21% African maternal contributions. Directional matings between Amerindian women and European men were detected, but differences involving Africans were not significant. Data about the specific origins of maternal lineages were also provided, and placed in a historical context.

Consanguinity in two Uruguayan cities: historical evolution and characteristics (1800-1994)

BACKGROUND

Information about consanguinity in Uruguay is scarce and limited to the end of the 20th century.

AIM

To determine the frequency and characteristics of consanguineous marriages, as well as chronological trends, in two Uruguayan cities over almost two centuries.

SUBJECTS AND METHODS

We analysed 28,393 Roman Catholic Church marriage records and Diocesan consanguinity dispensations belonging to the cities of Melo (Northeast), and Montevideo (South), for the period 1800--1994.

RESULTS

633 (2.23%) marriages were consanguineous. Among them, first cousin marriages were the most common (58.8% of all consanguineous marriages, including double consanguineous), especially those where the bride and groom were related through their maternal side. During the first decades of the 19th century both regions showed low levels of consanguinity. Consanguinity reached its maximum during the mid-1800s and decreased significantly throughout the 20th century. The overall mean coefficients of inbreeding were moderate in both cases, being greater in the Northeast (alpha=0.00165) than in the South (alpha = 0.00089).

CONCLUSIONS

The low level of consanguinity as well as the structure of consanguineous marriages (distribution by degrees) is similar to that found in other southern South American countries. Temporal trends are similar to those found in industrialized regions in Europe, with maximum inbreeding levels during the middle-late 19th century; however, the clear predominance of first cousin unions, differs from most of the data for European countries. Small differences between the two cities can be related to diverse facts, such as socio-economic conditions, ethnic origin, immigration, and sampling.

Association between diabetes type 1 and DQB1 alleles in a case-control study conducted in Montevideo, Uruguay

We studied HLA DQB1 allele frequencies and the relative risk (RR) of various genotypes in 72 type 1 diabetic patients and 40 control individuals in Uruguay. This is a tri-racial (Caucasian, Black and Indo-American) mixed population. The products of the polymerase chain reaction amplifications were hybridized with oligonucleotides by allele-specific oligonucleotide reverse or dot blot methods. Significant differences between these two groups were observed only for allele DQB1*0302 (35%, RR = 7.34, P<0.001). The frequency of the alleles carrying a non-aspartic acid residue at position 57 was significantly higher in the diabetic patients (85 vs 53%, P<0.001). In contrast, the frequency of Asp alleles was negatively associated with type 1 diabetes (RR = 0.20, P<0.001). The genotype DQB1*0302/DQB1*0201 (33%, RR = 5.41, P<0.05) was positively associated with this disease. The genotype frequencies associated with type 1 diabetes in our population were significantly different from what is known for Caucasian and Black populations as well as compared with another admixed population, from Chile.

Los sistemas de salud de Cuba y Uruguay en el contexto de América Latina: una reflexión

Se parte del análisis de diferentes factores socioeconómicos que han incidido en los sistemas de salud de América Latina, como la aplicación del modelo económico neoliberal y el proceso de globalización, que hacen que la salud sea vista como una mercancía. Posteriormente, se discute en qué medida estos factores inciden en diversos sectores de la población, y cómo afectan a la salud como bien colectivo; asimismo, se examinan los problemas que emanan de la privatización de la salud, y qué sucede cuando el Estado pierde su rol de garante de la seguridad social. Se analizan indicadores de salud de América Latina, realizándose estudios de correlación para visualizar sus asociaciones. De estos datos se concluye que los indicadores de salud están determinados en gran medida por los factores socioeconómicos; y que la práctica sanitaria debe centrarse en la atención primaria y de la educación en salud. Por último, se consideran en particular los casos de Uruguay y Cuba, dos ejemplos de buen desempeño en salud aunque con grandes diferencias históricas y de políticas de salud.

[Erythrocyte glutathione reductase in pregnant women with hemoglobin AA and AS]

PURPOSE

To evaluate the catalytic activity of the red cell enzyme, glutathione reductase (GR) in pregnant women with Hb AS and with Hb AA, and in a group of non-pregnant women with Hb AA, as well as the relationship of GR deficiency with Hb S.

PATIENTS AND METHODS

The catalytic activity was determined in presence and absence of FAD by means of a modified Long and Carson technique. 59 pregnant women with AS and 33 with AA phenotypes were studied.

RESULTS

Differences were found in the enzyme's catalytic activity with and without FAD, both in pregnant women with Hb AS (mean values 37.17 nka/g y Hb in whites and 42.84 nkat/g HS in afro people) and in those with Hb AA, and also in non-pregnant women with Hb AA. A high frequency of GR deficiency was found in all groups due to an insufficient riboflavin supply in diet.

CONCLUSION

A correlation between GR deficiency and Hb S could not be demonstrated. The coefficient of activity of red cell GR shows a tendency to increase in pregnancy due to certain riboflavin deficit of diet.

[Electrophoresis of 1,149 samples of umbilical cord blood and assessment of the heterogeneity of the relationship between gamma G and gamma A chains of fetal hemoglobin]

A total number of 1,149 specimens of cord-blood were subjected to cellulose acetate gel electrophoresis in order to estimate the incidence of haemoglobinopathies in newborn infants (NBI). It was found that 4.37% of black NBI and 0.54% of white NBI were AS carriers. Those samples with HbS or HbC were verified by means of agar-citrate electrophoresis at pH 6.2. Haemoglobin Bart was commonest in black (3.1%) than in white (0.4%) NBI. A slow haemoglobin variant was found with an alpha-chain mutation. The concentration of gamma G was estimated by separation of gamma G and gamma A chains with polyacrylamide gel electrophoresis, and it ranged between 52% and 94%, which could be attributed to the fact that the shift from HbF to HbA is not simultaneous in all the red-cell population.

Ciprofibrate, a carcinogenic peroxisome proliferator, increases the phosphorylation of epidermal-growth-factor receptor in isolated rat hepatocytes

Ciprofibrate, a hypolipidaemic drug with carcinogenic and peroxisome-proliferation effects in rat liver, was found to increase the phosphorylation of epidermal-growth-factor receptor in 32P-labeled isolated rat hepatocytes. This effect was suppressed by protein-kinase-C inhibitors, and was accompanied by an almost complete inhibition of the receptor autophosphorylation normally induced by its ligand. However, in vitro experiments showed that protein-kinase-C phosphorylation of purified epidermal-growth-factor receptor was activated by ciprofibroyl-CoA, the acyl-CoA derivative of the drug, but not by the unmodified drug. Neither compound affected the ligand induction of epidermal-growth-factor-receptor autophosphorylation in isolated liver membranes. These results suggest that metabolically produced ciprofibroyl-CoA in liver cells would activate protein-kinase-C and produce changes in epidermal-growth-factor-receptor function.

Hypolipidaemic drugs are activated to acyl-CoA esters in isolated rat hepatocytes. Detection of drug activation by human liver homogenates and by human platelets

The formation of acyl-CoA esters of the hypolipidaemic peroxisome proliferators clofibric acid, ciprofibrate and nafenopin was studied in isolated rat hepatocytes. The concentration of ciprofibroyl-CoA in the liver of ciprofibrate-treated rats was in the range of 10-30 microM. The three drugs formed acyl-CoA esters when incubated with isolated hepatocytes. Their formation was saturable and reached a plateau after 30 min incubation. Maximal intracellular concentrations of ciprofibroyl-CoA and clofibroyl-CoA (100 microM and 55 microM respectively) were attained at 0.5 mM of the free drugs in the incubation medium, whereas for nafenopin-CoA, the maximal intracellular concentration (9 microM) was reached at 1 mM-nafenopin. At low concentrations of the hypolipidaemic compounds in the incubation medium a significant proportion of the total intracellular drug was present as its acyl-CoA ester (25-35% for ciprofibrate). When isolated hepatocytes were incubated with a ciprofibrate concentration comparable with that observed in the blood of drug-treated rats (0.1 mM), ciprofibroyl-CoA attained an intracellular concentration similar to that previously observed in the liver of treated rats. The formation of ciprofibroyl-CoA by isolated rat hepatocytes was stimulated by the addition of carnitine and partially inhibited by the addition of palmitate. Further, it was shown that human liver homogenates synthesized ciprofibroyl-CoA at a rate similar to that observed for rat liver homogenates. Solubilized human platelets also formed ciprofibroyl-CoA, although at a rate two orders of magnitude lower than that of liver. The results support the view that acyl-CoA esters of hypolipidaemic peroxisome proliferators may be the pharmacologically active species of the drugs.

Palmitoyl-CoA and the acyl-CoA thioester of the carcinogenic peroxisome-proliferator ciprofibrate potentiate diacylglycerol-activated protein kinase C by decreasing the phosphatidylserine requirement of the enzyme

To gain insight into the mechanism by which long-chain acyl-CoA thioesters potentiate diacylglycerol-activated protein kinase C, the cofactor dependence of this activating effect was studied with purified rat brain enzyme and histone H1 as substrate. Using two different assay systems, palmitoyl-CoA was found to decrease greatly the amount of phosphatidylserine required to activate the kinase. No relative changes were observed in the dependence of the enzyme for other cofactors (diacylglycerol, ATP, and Ca2+) in the presence of palmitoyl-CoA. The potentiating effect of palmitoyl-CoA and the decrease in phosphatidylserine requirement of the kinase was also demonstrated using the 47-kDa protein of human platelets as substrate and platelet protein kinase C as source of enzyme. The acyl-CoA thioester of the carcinogenic peroxisome-proliferator ciprofibrate was also found to decrease the phosphatidylserine requirement of protein kinase C. The data suggest that acyl-CoAs may play a role in the regulation of protein kinase C activity.