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El objetivo de la presente investigación fue determinar los niveles de competencias genéricas en la enseñanza de Biología. Se aplicó el enfoque cuantitativo, de tipo descriptivo con diseño no experimental de corte transversal, la población fue de 65 estudiantes y 7 docentes de Biología-Ciencias Naturales y Biología - informática. Para validez y confiabilidad de los instrumentos, se realizó con la técnica de juicio de expertos y el coeficiente Alfa de Cronbach obtenido fue de 0,905. Los resultados demuestran diferencias significativas de un 46,8 % los docentes aplican en un nivel medio las competencias genéricas, 33,9% un nivel alto, y el 19,4% un nivel bajo, siendo la competencia interpersonal (46,8%,) y el trabajo en equipo una de las competencias que presenta el nivel más alto de aplicación en los docentes y estudiantes, seguida de la competencia sistémica (37,1%) y las competencias instrumentales (30,6%), que son las menos desarrolladas y dentro de este grupo las capacidades del pensamiento crítico ,resolución de problemas, gestión de la información ,creatividad y gestión de proyectos, son las que demandan mayor atención, para desarrollar habilidades en el actuar eficiente de su ciudadanía y preparar profesionales capaces de resolver problemas de su contexto y ámbito laboral.

To investigate the long-term effects of glucose on the function of human fetal islets we cultured islet-like cell clusters (ICC) obtained from 12 human fetuses with a mean age of 16.1 weeks in media containing 2.8, 11.1 or 16.7 mM glucose. On the 8th day of culture, the ICC that had been maintained in 16.7 mM glucose contained 60% less insulin than the ICC cultured in 2.8 mM glucose. However, insulin release was similar in both groups, and was not affected by a 24-h incubation in high vs. low glucose. Also (pro)insulin biosynthesis was not significantly affected. During a 24-day culture period, the total release of insulin and glucagon was similar in all glucose concentrations. The ICC released about 75 % of their insulin content but only 15 % of their glucagon content during the last 48 h of the 24-day culture period, again regardless of glucose concentration in media. Insulin release was insensitive to acute glucose and leucine challenges in perifusion experiments after culture for 1, 5, 8 or 16 days in 11.1 mM glucose, whereas glucagon was always a potent stimulus. In conclusion, the function of cultured young human fetal islet cells is remarkably independent of glucose, even during prolonged exposure. Moreover, the primary role of glucagon in fetal life may be that of a paracrine stimulator of β-cell function.

A tissue culture system for the growth of human fetal and infantile thymic epithelial (TE) cells has been established and characterized. We have investigated the effects of infection of these cells by human cytomegalovirus (CMV), measles virus, and human immunodeficiency virus type-1 (HIV-1). In the case of CMV, morphological changes were apparent by 2-4 days after viral inoculation of infantile TE cells. CMV-related antigens were detected by immunofluorescence after 12 days, and progeny infectious CMV was recovered from culture media after 18 days. Following infection by measles virus, distinctive, multinucleated giant TE cells appeared in both cultures of fetal and infantile TE cells. Measles virus-inoculated TE cells displayed an altered phenotype, as revealed by reaction with monoclonal antibodies with specificity for a variety of TE markers. Finally, infection of TE cells by HIV-1 resulted in cellular disarrangement, increased numbers of Hassall's corpuscles, and multinucleated giant cells. An increase in the number of cells reactive with monoclonal antibodies, specific for Hassall's corpuscles, was observed in the case of cells infected by either measles virus or HIV-1. These findings suggest that a variety of different viruses can successfully infect thymic epithelial tissue. Because of the important role of the thymus in development of the immune system, it is reasonable to conclude that viral infection of thymic tissue might play an important role in virus-mediated suppression of immune responsiveness.

Tissue monolayer cultures of human fetal islets of Langerhans were infected with human cytomegalovirus (CMV). On the fourth day after inoculation, morphologic changes of mono-layers were observed, including rounding up and floating of many cells. In addition, after this time CMV late antigen (LA) was detected in the inoculated cells. On the seventh day, CMV was recovered from the culture medium, and infected beta cells were identified by use of a double-label antibody technique. However, CMV apparently did not cause direct destruction of beta cells nor did infection by CMV lead to changes in production of insulin as measured by radioimmunoassay. Thus, de-spite the fact that CMV can successfully infect a variety of cells in fetal islets of Langerhans, the absence of a significant effect on beta cells does not support the notion that congenital CMV infection is involved in the origin of insulin-dependent diabetes mellitus.

We have examined control subjects and patients in an effor to discover a metabolic basis for dominantly inherited osterogenesis imperfecta (OI). Studies were carried out in vitro with cultured skin fibroblasts obtained from OI patients, and in vivo on peptide-bound hydroxyproline excretion in urine. Urinary hydroxyproline excretion (milligrams/24 hr) adjusted for age is essentially normal in OI patients, although the mean excretion rate is below average. The latter finding is presumably a reflection of the smaller body mass of OI patients. The OI skin fibroblasts, matched for age of donor, site of biopsy, phase of growth, and generation number in culture, incorporated L-proline into hot trichloroacetic acid (TCA)-soluble protein (collagen) at normal rates. The rate of conversion of proline to hydroxyproline in the nascent polypeptides is also normal in OI. Incorporation of L-lysine was also normal in OI. These findings indicate that peptide synthesis of collagen is not impaired in OI. Rates of galactose incorporation into collagen and the extractability of collagen into normal saline or 0.2 M citric acid were all normal both in OI cells and in the culture medium recovered from the monolayer. These findings, in combination with the urinary data on hydroxyproline excretion in vivo reveal that cross-linking and export of collagen in OI is essentially normal. The elution profile after ion exchange chromatography of fibroblast collagen on carboxymethyl (CM)--Sephadex was also examined. The normal 2/1 ratio of peak 1 (largely alpha 1(1) chains) to peak 2 ) largely alpha 2 chains) was found in OI fibroblast extracts, which implies that synthesis and initial aggregation of the two types of polypeptide to yield (alpha1(1))-2 alpha 2 collagen composition is not abnormal in OI. Despite the negative biochemical findings, a consistent defect in the morphology of OI cells was identified in the log phase and the confluent phase of monolayer cultures. The finding is characterized by irregular packing of the aggregated cells and by an irregular tessellated appearance of the individual OI fibroblast. This observation reassures us that the inherited defect is expressed in vitro.

Measles virus can replicate in cultures of both infantile and fetal human thymic epithelial cells. Virus-induced cytopathology including syncytium formation was first evident around 24 hr after viral inoculation of these cultures. At the same time, the cultures began to lose their characteristic thymus-like organizational structure. Viral antigens were detected in infected cells by indirect immunofluorescence, and the presence of progeny virions was demonstrated in culture fluids.

The effects of recombinant human growth hormone (GH, 1 µg/ml) and insulin-like growth factor I (IGF-I, 200 ng/ml) on the production of insulin and glucagon by human fetal islet-like cell clusters (ICCs) were studied in tissue culture. ICCs were derived after collagenase digestion and culture of pancreases from 16 fetuses (mean gestational age 15.6 wk). The ICCs were cultured with or without GH or IGF-I for 7 or 31 days. Basal rates of insulin and glucagon production were not altered by GH during the first 17 days of culture, but the release of both hormones was increasingly augmented by GH during the last 2 wk of culture (131% increase in insulin and 85% in glucagon compared with controls). ICCs cultured for 7 days in the presence of GH secreted more insulin when incubated for 120 min in 20 mM than in 2 mM glucose (2.1-fold response, P < .05), whereas ICCs mantained in basal medium did not respond to glucose. GH had no effect on DNA and insulin content or insulin biosynthesis. Exogenous IGF-I caused a 28% suppression of insulin release (P < .05) between days 4 and 10 of culture but induced a 49% increase in the mean secretion rate during the last week (days 25–31, P < .01). Glucagon release was not affected by exogenous IGF-I. In contrast to GH, exogenous IGF-I induced a twofold increase in the DNA content of the 7-day-cultured ICCs. However, insulin biosynthesis and release were markedly suppressed. We conclude that GH influences the functional maturation of human fetal islet cells in vitro. The effects of GH could not be reproduced by the addition of IGF-I, suggesting a direct rather than a somatomedin-mediated action for GH.

Cytomegalovirus (CMV) has often been cited as a cause of immune suppression in children, yet little is known of the mechanisms through which this agent might affect immune function. We have succeeded in using CMV to productively infect cultured human fetal and infantile thymic epithelial (TE) cells. Morphological changes were apparent by 2–4 days after viral inoculation. CMV-related early antigen (EA) and late antigen (LA) were detected by immunofluorescence after 8 days, and progeny infectious CMV was recovered from culture media after 12–17 days. TE cells that reacted with monoclonal antibodies specific for keratin and for GQ ganglioside were predominant throughout the culture period. In contrast, infection by CMV resulted in a significant decrease in numbers of cells reactive with monoclonal antibodies specific for mesoderm-derived components. Inoculation of TE cells with CMV also caused a diminution in levels of detectable interleukin-1 (IL-1)-related antigen by 17 days after infection.

The structural and biochemical ontogeny of 14 mid-trimester (12.0–19.5 wk) human fetal endocrine pancreata were examined. Each pancreas was halved at the region of the isthmus into duodenal (D) and splenic (S) portions, and islets, isolated from each of the two portions, were aliquoted and grouped according to diameter into 4 categories: (1) > 300 μm (2) 300–200 μm (3) 200–100 μm (4) 100 μm. At all fetal ages, the number of islets isolated from the splenic half was greater than from the duodenal half, and the number of islets increased as their diameter decreased. The mean total cell number per islet for each of the 4 categories are reported: (1)(D) 30,810 (S) 28,450; (2)(D) 10,970 (S) 10,250; (3)(D) 3,390 (S) 3,460; (4)(D) 1,930 (S) 1,840. Measurement of islet insulin (IRI), glucagon (IRG), and somatostatin (IRS) by radioimmunoassay showed a progressive increase with time in the content of all three hormones in all islets from both halves of the pancreas (with the exception of the smallest islets of 300 μm) islets. In contrast, pancreatic polypeptide (IRPP) shows no significant increase. With the exception of the smallest islets (100 μm), all splenic-half islets contain a significantly greater content of IRI, IRG, and IRS compared with their duodenal-half match while the content of IRPP is significantly greater in the duodenal-half islets. In addition, all islets with the exception of the largest (>300 μm), contained equal quantities of IRG and IRS and these results were apparent at 12 wk gestation. These data provide new insights into the ontogeny of individual islet cells during the mid-trimesteric period and serve as a basis for future studies of both normal and abnormal pancreatic development.

We have succeeded in growing the HTLV-IIIB strain of human immunodeficiency virus type 1 (HIV-1) in cultured human thymic epithelial (TE) cells. Expression of the HIV-1 proteins p17 and p24 was detected by immunofluorescence and reached a peak at 3 days after infection. Antigen capture and reverse transcriptase assays were used to detect HIV-1 in culture fluids, with positive results also being realized. The infection was cytolytic; cellular disarrangement, increased numbers of Hassall's corpuscles, and giant cells first appeared in monolayers of TE cells at 2 days after inoculation. By 4 days these changes were increased, and by 7 days, retraction and involution of TE cells were evident. The infection of TE cells by HIV-1 was blocked by preincubation with monoclonal OKT4A antibodies directed against CD4 target molecules.

Morphology, yield and function were studied in cultured islet-like cell clusters (ICC) from 140 human fetal pancreata obtained after abortions of different types performed at 11-23 weeks of gestation (12 by hysterotomy, 75 by mechanical dilation and extraction, and 53 induced with prostaglandin). After collagenase digestion and culture in medium supplemented with 10% human serum, up to 2000 free-floating ICC were formed from a single pancreas. Randomly scattered insulin- and glucagon-immunoreactive cells were found in the medullary part of the ICC. More than 100 ICC developed in 100% of the hysterotomies and 87% of the mechanical abortions, but in only 53% of the prostaglandin-induced abortions. Insulin and glucagon levels in the culture medium decreased rapidly during the first 7 days of culture, but then remained stable for at least 31 days. The hysterotomy-derived ICC responded to 10 mmol/l theophylline plus 20 mmol/l glucose by a 12.2 +/- 3.1 (SEM, N = 7) fold increase in insulin release, as compared with a 5.4 +/- 0.9 fold response of the prostaglandin ICC (N = 16; P less than 0.02). Despite the low proportion of B-cells, (pro)insulin biosynthesis accounted for 10% of the total protein biosynthesis in low (2 mmol/l) glucose. In conclusion, the yield and viability of the ICC were clearly better, if prostaglandin had not been used for the induction of the abortion.The morphology, yield, and functional integrity of islet-like cell clusters (ICC) from 140 human fetal pancreata obtained after abortions performed at 11-23 weeks of gestation were examined. The culture method developed for this study was based on the formation of numerous ICC from collagenase-digested fetal pancreata after culture in medium supplemented with human serum. 12 of the abortions were performed by hysterotomy, 75 by mechanical dilatation and extraction, and 53 were induced by prostaglandin. Up to 2000 free-floating ICC were formed from a single pancreas. More than 100 ICC per pancreas were isolated from 100% of the fetuses from hysterotomies and 87% of the fetuses from mechanical abortions, but from only 53% of the tissues from prostaglandin-induced abortions. Insulin and glucagon levels in the culture medium decreased rapidly during the 1st 7 days of culture, but then remained stable for at least 31 days despite the decrease in the number of ICC. Stimulation of the ICC with glucose and theophylline promptly released insulin. Insulin release was stimulated 12.2-fold in hysterotomy-derived ICC, 6.5-fold in ICC from mechanical abortions, and 5.4-fold in ICC from prostaglandin-induced abortions. Despite the low proportion of B cells, insulin biosynthesis accounted for 10% of the total protein biosynthesis in low glucose. This finding suggests that the nonendocrine cells of the ICC were less active and viable than the endocrine ones. Overall, this study demonstrates a clear correlation between the morphologic and functional characteristics of cultured fetal tissue, with the number of ICC reflecting the degree of tissue viability.

Variably-sized, histologically intact islets were isolated from 14 human fetal pancreases (12.0-19.5 wks. gestation) and grouped according to gestation age, region of the pancreas (splenic and duodenal) and diameter sizes. The mean number of cells/islet, based on DNA/islet was ~30,000 (>300μm diameter), ~11,000 (200-300μm), ~3,500 (100-200μm) and ~2,000 (