Libros de medicina para internistas / Books of medicine for internists

Resumen: La bibliografía médica, nacional y extranjera, está en constante crecimiento, de ahí la necesidad de que los médicos internistas cuenten con una guía de los textos más conocidos y de mayor utilidad y actualidad. Es debido a esta necesidad que me permito presentar una lista de los libros básicos para la medicina interna basada y tomando en cuenta el temario para sustentar el examen del Consejo Mexicano de Medicina Interna, AC.

Abstract: The medical literature, national and foreign, is constantly growing, hence the need for internists to have a guide to the most known and most useful and current texts. It is due to this need that I allow myself to present a list of the basic books for internal medicine taking into account the agenda to support the examination of the Mexican Council of Internal Medicine, AC.

Los mitos alimentarios y su efecto en la salud humana / Food myths and their impact on human health

Resumen La alimentación humana a través de la historia se ha visto influida por el folklore, las creencias religiosas, cuestiones político-económicas y por costumbres y modas, favorecidas actualmente estas últimas por los medios de comunicación impresos y electrónicos. En ocasiones, algunas conductas alimentarias carecen de fundamento científico, por lo que pueden repercutir, desfavorablemente, en la salud humana. La invención de mitos alimentarios crece día con día, constituyendo un reto para el profesional, que trata de brindar a sus pacientes explicaciones lógicas y fundamentadas acerca de la conveniencia de seguir tal o cual recomendación sobre su alimentación, debiendo, además, adecuarse a las enfermedades que padezca cada caso para no agravar su padecimiento. Además de la Medicina Interna o de la Nutriología, en otras especialidades médicas también hay determinados mitos, sin ser su análisis el objetivo primario del artículo, en éste se pretende hacer un breve análisis de los mitos alimentarios más comunes, proporcionando algunos detalles explicativos para su comprensión.

Abstract Human food throughout history has been influenced by folklore, by religious beliefs, by political economic issues, and by customs and fashions, currently favored these last ones by the print and electronic media. Sometimes, some dietary behaviors lack of scientific foundation, reason why they can have an unfavorable repercussion in the human health. The invention of food myths grows day by day, constituting a challenge for the professional, who tries to provide his patients with logical and informed explanations about the advisability of following this or that recommendation about their diet, and must also be adapted to the diseases that present each case, so as not to aggravate their suffering. In addition to Internal Medicine or Nutrition, in other medical specialties there are also certain myths, without its analysis being the primary objective of the article, it is only intended to make a brief analysis of the most common food myths, providing some explanatory details for their understanding.

Fungal biodegradation of dibutyl phthalate and toxicity of its breakdown products on the basis of fungal and bacterial growth.

Phthalates are esters of phthalic acid that give flexibility to polyvinyl chloride. Diverse studies have reported that these compounds might be carcinogenic, mutagenic and/or teratogenic. Radial growth rate, biomass, hyphal thickness of Neurospora sitophyla, Trichoderma harzianum and Aspergillus niger, grown in two different concentrations of dibutyl phthalate (DBP) (500 and 1,000 mg/l) in agar and in submerged fermentation were studied. The inhibitory concentration (IC50) and the constant of biodegradation of dibutyl phthalate in Escherichia coli cultures were used to evaluate toxicity. The radial growth rate and thickness of the hypha were positively correlated with the concentration of phthalate. The pH of the cultures decreased as the fermentation proceeded. It is shown that these fungi are able to degrade DBP to non-toxic compounds and that these can be used as sole carbon and energy sources by this bacterium. It is demonstrated that the biodegradation of the DBP is directly correlated with the IC50. This is the first study that reports a method to determine the biodegradation of DBP on the basis of the IC50 and fungal growth, and the effect of this phthalate on the growth and thickness of hyphae of filamentous fungi in agar and in submerged fermentation.

Growth and laccase production by Pleurotus ostreatus in submerged and solid-state fermentation.

Pleurotus ostreatus showed atypical laccase production in submerged vs. solid-state fermentation. Cultures grown in submerged fermentation produced laccase at 13,000 U l(-1), with a biomass production of 5.6 g l(-1) and four laccase isoforms. However, cultures grown in solid-state fermentation had a much lower laccase activity of 2,430 U l(-1), biomass production of 4.5 g l(-1), and three laccase isoforms. These results show that P. ostreatus performs much better in submerged fermentation than in solid-state fermentation. This is the first report that shows such atypical behavior in the production of extracellular laccases by fungi.

Mycelial growth of strains of Pleurotus ostreatus developed on agar and its correlation with the productivity in pilot production farm

Radial growth rate, intracellular laccases and proteases activities, and protein content were evaluated in five strains of Pleurotus ostreatus, grown on starch-based and glucose-based agar media containing different concentrations of the glucose analogue 2-deoxyglucose (2-DG). Productivity of the strains in pilot scale cultivation was also determined. The mycelium of four strains had approximately between 0.6- to 3-fold higher protein content when grown on glucose medium containing 0.01 g/L of 2-DG than when grown on glucose medium. The radial growth rate and intracellular laccases activity of some strains showed a positive and a negative correlation with the productivity, respectively. These results suggest that the strains with high radial growth rate and low intracellular laccases activity on glucose without 2-DG, on starch without 2-DG or on glucose containing 0.01 g/L of 2-DG are highly productive in pilot production farm.

Avaliou-se o crescimento radial, as atividades de proteases e lacases e o conteúdo protéico de cinco cepas de Pleurotus ostreatus cultivado em agar à base de amido e à base de glicose contendo diferentes concentrações de 2-deoxiglicose (2-DG), um análogo da glicose. A produtividade das cepas em cultivo em escala piloto foi também determinada. Em quatro cepas o conteúdo protéico do micélio foi aproximadamente 0,6 a 3 vezes maior quando foram cultivadas em meio à base de glicose contendo 0,01g/L de 2-DG. O crescimento radial e a atividade de lacases apresentaram correlação positiva e negativa, respectivamente, com a produtividade. Esses resultados sugerem que as cepas com elevada taxa de crescimento radial e baixa atividade de lacases em glicose sem 2-DG, ou em amido sem 2-DG, ou em glicose com 0,01 g/L de 2-DG, são altamente produtivas em cultivo em escala piloto.

Growth of Pleurotus ostreatus on wheat straw and wheat-grain-based media: Biochemical aspects and preparation of mushroom inoculum.

Mycelial growth, intracellular activity of proteases, laccases and beta-1,3-glucanases, and cytoplasmic protein were evaluated in the vegetative phase of Pleurotus ostreatus grown on wheat straw and in wheat-grain-based media in Petri dishes and in bottles. The productivity of the wheat straw and wheat-grain-based spawn in cylindrical polyethylene bags containing 5 kg of chopped straw was also determined. We observed high activity of proteases and high content of intracellular protein in cultures grown on wheat straw. This suggests that the proteases are not secreted into the medium and that the protein is an important cellular reserve. On the contrary, cultures grown on wheat straw secreted laccases into the medium, which could be induced by this substrate. P. ostreatus grown on media prepared with a combination of wheat straw and wheat grain showed a high radial growth rate in Petri dishes and a high level of mycelial growth in bottles. The productivities of wheat straw and wheat-grain-based spawn were similar. Our results show that cheaper and more productive mushroom spawn can be prepared by developing the mycelium on wheat straw and wheat-grain-based substrates.

Differential patterns of constitutive intracellular laccases of the vegetative phase of Pleurotus species.

The constitutive intracellular laccase activity of ten strains of Pleurotus spp. was determined in vitro and by zymograms, using different substrates. Differences in the in vitro activities were observed between all the strains; however, zymogram patterns were only similar for strains within same species, independently of any of the three substrate (2,6-dimethoxyphenol, p-anisidine or o-tolidine) used. The differences observed in the number and positions of the isoforms in the gel suggest that laccase zymograms can be used to differentiate species of this organism.

Simple staining detects ultrastructural and biochemical differentiation of vegetative hyphae and fruit body initials in colonies of Pleurotus pulmonarius.

AIMS: To know the ultrastructural and biochemical differences of vegetative hyphae and fruit body initials in colonies of Pleurotus pulmonarius. METHODS AND RESULTS: Feulgen reagent was used to detects differentiation of hyphae. The intracellular laccases, proteases and beta-1,3-glucanases activity, content of cytoplasmic protein, glycogen and glucans in the cell wall were evaluated in hyphae of fruit body initials and in vegetative hyphae. The thickness of hyphal walls of the vegetative hyphae was also evaluated. Substantial biochemical changes were observed in hyphae of different zones of the fruiting colony. Hyphae at the periphery had thinner walls than in the centre of the colony. CONCLUSION, SIGNIFICANCE AND IMPACT OF THE STUDY: Staining correlated with the enzymatic activity, protein, glycogen and glucans, in mycelium and in fruit body initials. The implications are that hyphal maturity in P. pulmonarius involves storage of glucans, in part at least, in the form of a thickened hyphal wall.

Physiology of a colony of Pleurotus pulmonarius grown on medium overlaid with a Cellophane membrane.

The physiology of a colony of Pleurotus pulmonarius grown on potato dextrose agar overlaid with a Cellophane membrane (PDA-WC) was studied. On PDA-WC, the colony presented higher biomass density and productivity of fruit body formation (4.84+/-0.23 mg mycelial biomass/cm2 and 23.7+/-3.12 microg ml(-1) h(-1), respectively) than that which developed on potato dextrose agar without Cellophane (PDA-OC; 0.26+/-0.01 mg mycelial biomass/cm2 and 10.8+/-1.57 microg ml(-1) h(-1), respectively). In cultures developed on PDA-WC, intracellular laccases and beta-1,3-glucanases activities were lower [12+/-0.9 arbitrary units (AU)/g mycelial biomass and 1.33+/-0.1 international units (IU)/g mycelial biomass, respectively] than those observed on PDA-OC (20.65+/-1.0 AU/g mycelial biomass and 3.67+/-0.2 IU/g mycelial biomass, respectively). In cultures developed on PDA-WC, intracellular protein and glycogen concentrations were lower (1.9+/-0.9 and 117+/-3.5 mg/g mycelial biomass, respectively) than those observed on PDA-OC (14.3+/-1.1 and 347+/-2.9 mg/g mycelial biomass, respectively). The radial growth rate and the content of glucans in the cell wall were not significantly different between cultures developed on PDA-WC and PDA-OC. These results show that the use of the Cellophane as a tool to study in vitro fungal physiology might affect the interpretation of experimental results, since the physiology under otherwise similar conditions was different on medium with and without Cellophane.

Exopectinases produced by Aspergillus niger in solid-state and submerged fermentation: a comparative study.

Exopectinase production by Aspergillus niger was compared in submerged fermentation (SmF) and solid-state fermentation (SSF). SSF was carried out using polyurethane foam (PUF) as the solid support. The purpose was to study the effect of sucrose addition (0 or 40 g/l) and water activity level (A(w)=0.99 or 0.96) on the level of enzyme activity induced by 15 g/l of pectin. Mycelial growth, as well as extracellular protease production, was also monitored. Sucrose addition in SmF resulted in catabolite repression of exopectinase activity. However, in SSF, an enhancement of enzyme activity was observed. Protease levels were minimal in SSF experiments with sucrose and maximal in SmF without sucrose. Exopectinase yields (IU/g X) were negligible in SmF with sucrose. The high levels of exopectinase with sucrose and high A(w) in SSF can be explained by a much higher level of biomass production without catabolite repression and with lower protease contamination.

Role transition from graduate to staff nurse: a qualitative analysis.

The purpose of this study was to describe the initial steps in the role transition of graduate to staff nurse. During the first 3 weeks of an orientation to a clinical unit in an acute care hospital, graduate nurses and their preceptors used feedback sheets to document the learning activities of the graduate nurse, communicate the need for and evaluation of learning experiences, and plan activities to meet the continued needs of graduate nurses. Daily feedback sheets from 27 orientees and preceptors were analyzed using content analysis. A model representing the process and components of role transition was developed. The model was based on five themes which emerged from the data: Real Nurse Work, Guidance, Transitional Processes, Institutional Context, and Interpersonal Dynamics. Analysis of results revealed that the initial transition of a graduate nurse to the role of a staff nurse was a dynamic and interactive process occurring between the graduate nurse and the preceptor. Guided learning led to progress in balancing increasingly complex care within a specific institution. Interpersonal dynamics among staff, preceptors, and graduate nurses affected the process of role transition.

Correlation between dobutamine stress transesophageal echocardiography, thallium 201-dipyridamole scintigraphy and coronary angiography in the early detection of myocardial ischemia.

In order to establish the sensitivity and specificity of transesophageal stress echocardiography with dobutamine (TEE-dobutamine) in the early detection of myocardial ischemia we studied 30 consecutive patients from the Coronary Care Unit (CCU) of the Hospital de Cardiología, Centro Médico Nacional Siglo XXI. The results were correlated with thallium-201-dipyridamole scintigraphy (TDS), and coronary angiography. Two groups were formed: Group I-20 patients, 18 females/2 males, aged 37-73 years (mean 55 years) within the first week of myocardial infarction and/or unstable angina; Group II-10 patients, five males/five females, aged 35-65 years (mean 48 years) with atypical chest pain but with high suspicion of CHD. All group I patients, and none of group II, had significant stenoses on coronary angiography. Twenty patients had a positive TDS (18 patients from group I and two from group II). Twenty one patients had a positive test with TEE-dobutamine, 20 from group I and one from group II, which yields a sensitivity of 100%, a specificity of 90%, positive predictive value of 95% and negative predictive value of 100%.

Effect of kainic acid administration to prepubescent rats on cholinergic markers in selected brain regions of adult rats.

Systemic kainic acid administration to prepubescent rats, in a convulsant dose, results in permanent changes in behaviour, learning and memory in adulthood (Holmes et al., 1988, Epilepsia 29, 721-730). With regard to the hypothesis that cholinergic mechanisms play a crucial role in cognitive processes, M1- and M2-muscarinic acetylcholine receptors, choline acetyltransferase, and high-affinity choline uptake as well as benzodiazepine receptors were studied in selected cortical regions (frontal, temporal, somatosensory, visual, piriform cortex), in amygdala, hippocampus, and in the nucleus basalis of Meynert from adult rats, which received at the age of 25 days a single dosage of 11 mg/kg, s.c. kainic acid. Kainic acid treatment of prepubescent rats resulted in the adult brain in decreased numbers of the total population of muscarinic acetylcholine receptors in frontal (by 27%, P < 0.05, two-tailed Student's t-test), temporal (22%, P < 0.05), and piriform cortex (31%, P < 0.05), in amygdala (24%, P < 0.05), and nucleus basalis of Meynert (39%, P < 0.02). The binding affinity was unchanged in these regions. However, in the hippocampus, the dissociation constant was significantly increased following kainic acid treatment, while the receptor numbers remained unchanged. Analysis of competition experiments with the muscarinic antagonist pirenzepine revealed that the reductions of muscarinic acetylcholine receptors in the cortical regions after kainic acid treatment are mainly due to decreases in the number of the muscarinic M1-receptor subtype. In the amygdala, the numbers of both M1- and M2-receptor subtypes are reduced.(ABSTRACT TRUNCATED AT 250 WORDS)