Genetic linkage map of the edible basidiomycete Pleurotus ostreatus

We have constructed a genetic linkage map of the edible basidiomycete Pleurotus ostreatus (var. Florida). The map is based on the segregation of 178 random amplified polymorphic DNA and 23 restriction fragment length polymorphism markers; four hydrophobin, two laccase, and two manganese peroxidase genes; both mating type loci; one isozyme locus (est1); the rRNA gene sequence; and a repetitive DNA sequence in a population of 80 sibling monokaryons. The map identifies 11 linkage groups corresponding to the chromosomes of P. ostreatus, and it has a total length of 1,000.7 centimorgans (cM) with an average of 35.1 kbp/cM. The map shows a high correlation (0.76) between physical and genetic chromosome sizes. The number of crossovers observed per chromosome per individual cell is 0.89. This map covers nearly the whole genome of P. ostreatus.

[Cardioinhibitory vagal response not related to pain, and induced by radiofrequency application during ablation of right posteroseptal accessory pathway]

Inappropriate sinus tachycardia is the most common arrhythmia induced by radiofrequency energy delivery in the posteroseptal area. It has been suggested that this could be secondary to parasymphathetic nerve injury. We report a patient with extreme sinus bradycardia and PR interval prolongation induced by radiofrequency energy delivered in the coronary sinus ostium area, but not related to any other stimulus. The most probable mechanism of the disorder was transient stimulation of the vagal afferent nerve fibers located in this anatomical area.

[Oblique orientation of the accessory pathway demonstrated by radiofrequency application]

Activation mapping of atrial and ventricular insertion has suggested an oblique orientation of some accessory pathways. However, this aspect has not been demonstrated by radiofrequency application. This report presents two patients with Wolff-Parkinson-White syndrome and an accessory pathway with bidirectional conduction and oblique orientation. The accessory pathway oblique orientation was demonstrated by transient and permanent conduction abolition following radiofrequency application in two separate ventricular and atrial sites. These findings may explain the failure to ablate accessory pathway by radiofrequency application in the ventricular side of the mitral annulus guided by retrograde atrial activation occasionally observed in patients with a concealed accessory pathway.

Molecular tools for breeding basidiomycetes

The industrial production of edible basidiomycetes is increasing every year as a response to the increasing public demand of them because of their nutritional properties. About a dozen of fungal species can be currently produced for food with sound industrial and economic bases. Notwithstanding, this production is threatened by biotic and abiotic factors that make it necessary to improve the fungal strains currently used in industry. Breeding of edible basidiomycetes, however, has been mainly empirical and slow since the genetic tools useful in the selection of the new genetic material to be introduced in the commercial strains have not been developed for these fungi as it was for other organisms. In this review we will discuss the main genetic factors that should be considered to develop breeding approaches and tools for higher basidiomycetes. These factors are (i) the genetic system controlling fungal mating; (ii) the genomic structure and organisation of these fungi; and (iii) the identification of genes involved in the control of quantitative traits. We will discuss the weight of these factors using the oyster mushroom Pleurotus ostreatus as a model organism for most of the edible fungi cultivated industrially.

[Improving the quality of clinical interview teaching: evaluation of an intervention with medical students]

BACKGROUND

Quality of clinical interview is a key issue both for patient satisfaction and for diagnostic efficiency. Its adequacy relates to better clinical diagnosis treatment plans and patient compliance.

AIM

To measure the quality of interviews performed by medical students in three Chilean medical schools before receiving specific training on the subject and to compare the scores obtained after introductory courses on interview.

MATERIAL AND METHODS

The interviews were videotaped and then evaluated using an objective scale, that measures 33 skills grouped in six areas: opening, problem exploration, non verbal facilitation, interpersonal patient reaction and closing. The students were assigned to an experimental group that received an interactive workshop with role-plays, vignettes and videotape feedback, and to a non intervention group that received the usual bedside training on medical interviews.

RESULTS

Both groups shared the same skill level before the training, with better scores on nonverbal, patient reaction and problem exploration, and worse ones on closing and interpersonal skills. Comparing pre and post-test results, the overall score improved in the experimental group (from 33.2 to 38.3, p = 0.002) and worsened among non intervened students. There were statistically significant changes for opening (p < 0.002), problem exploration (p < 0.05), non verbal facilitation (p < 0.0001) and closing (p < 0.0001).

CONCLUSIONS

It is important to train students not only in specific knowledge contents but in the process of interview. This training should encourage the development of empathy and closing skills.

Left ventricular function and autonomic nervous system balance during two different stages of the menstrual cycle

We studied the left ventricular function and cardiac autonomic nervous system balance variations during two different stages of the menstrual cycle. These two variables, as well as plasmatic estradiol and progesterone concentrations, were measured in a drug-free state in 20 women (29+/-6 year-old) with regular menstrual periods. A clinical evaluation, an echo-Doppler and a Valsalva manoeuvre were performed in all the patients on the third day of their menstrual cycle (follicular phase) and three days prior to their next menstrual cycle (luteinizing phase). When comparing the results obtained in these two phases, a statistically significant increase was put forward in plasmatic estradiol (50.6+/-24 vs. 127.3+/-52.8 pg/ml) and progesterone (0.37+/-0.42 vs. 11.92+/-10.8 ng/ml) concentrations, Valsalva index (1.55+/-0.22 vs. 1.67+/-0.33; P=0.044) and E/A mitral wave ratio (1.63+/-0.36 vs. 1.75+/-0.35, P=0.02). The right and left atrial volumes, left ventricular volumes and ejection fraction were similar in the two menstrual phases studied. We conclude that the autonomic nervous system balance and the left ventricular diastolic function suffer significant changes during the luteinizing phase of the menstrual cycle in normal women.

Pregnancy-related mortality in Guatemala, 1993-1996

To select the proper interventions that could prevent maternal mortality, adequate and appropriate maternal mortality data are needed. Nevertheless, the quality and quantity of information and the scope of maternal health- and death-related data are inadequate in many countries, particularly in the developing world. From January 1993 to December 1996 a surveillance program in maternal mortality was developed to conduct surveillance studies in the department of Guatemala, Guatemala. With an active surveillance system, our approach gave a more complete picture of maternal death and produced information on the specific causes of maternal mortality. Using multiple sources of information, we reviewed and analyzed all deaths of women of childbearing age (10 to 49 years). Each death was investigated to determine whether it was pregnancy-related or not. The maternal mortality ratio for the four-year study period was 156.2 deaths per 100,000 live births. Women 35 and older had a higher risk of maternal death than women under that age. Women who were 35-39 years old had a maternal death risk almost three times as high as women aged 20-24. For women who were 40 or older the risk was more than double that of women 20-24 years old. Overall, the two leading causes of maternal mortality were infection and hemorrhage. Vaginal deliveries where there was medical assistance had the highest rate of delivery-related maternal death from general infection. In deliveries attended by nonmedical personnel, delivery-related maternal deaths from hemorrhage were most frequently associated with retained placenta. Developing countries are called on to implement systems that can provide continuous and systematic data collection so that policymakers and health managers have adequate information to design proper interventions to save women's lives.

Molecular karyotype of the white rot fungus Pleurotus ostreatus

The white rot fungus Pleurotus ostreatus is an edible basidiomycete with increasing agricultural and biotechnological importance. Genetic manipulation and breeding of this organism are restricted because of the lack of knowledge about its genomic structure. In this study, we analyzed the genomic constitution of P. ostreatus by using pulsed-field gel electrophoresis optimized for the separation of its chromosomes. We have determined that it contains 11 pairs of chromosomes with sizes ranging from 1.4 to 4.7 Mbp. In addition to chromosome separation, the use of single-copy DNA probes allowed us to resolve the ambiguities caused by chromosome comigration. When the two nuclei present in the dikaryon were separated by protoplasting, analysis of their karyotypes revealed length polymorphisms affecting various chromosomes. This is, to our knowledge, the clearest chromosome separation available for this species.

Identification of incompatibility alleles and characterisation of molecular markers genetically linked to the A incompatibility locus in the white rot fungus Pleurotus ostreatus

Pleurotus ostreatus is a hetertothallic homobasidiomycete whose mating is controlled by a bifactorial tetrapolar genetic system. Although this mechanism is well accepted, there is a lack of knowledge about its molecular basis, as the incompatibility loci have not been cloned and sequenced. As a first step towards the elucidation of the molecular structure of the A-type incompatibility locus, molecular markers have been isolated which correspond to genomic sequences present in different strains of P. ostreatus but not in other higher basidiomycetae. These markers reveal single-copy genetic regions in which some degree of genetic variability can be detected.

Identification, characterization, and In situ detection of a fruit-body-specific hydrophobin of Pleurotus ostreatus

Hydrophobins are small (length, about 100 +/- 25 amino acids), cysteine-rich, hydrophobic proteins that are present in large amounts in fungal cell walls, where they form part of the outermost layer (rodlet layer); sometimes, they can also be secreted into the medium. Different hydrophobins are associated with different developmental stages of a fungus, and their biological functions include protection of the hyphae against desiccation and attack by either bacterial or fungal parasites, hyphal adherence, and the lowering of surface tension of the culture medium to permit aerial growth of the hyphae. We identified and isolated a hydrophobin (fruit body hydrophobin 1 [Fbh1]) present in fruit bodies but absent in both monokaryotic and dikaryotic mycelia of the edible mushroom Pleurotus ostreatus. In order to study the temporal and spatial expression of the fbh1 gene, we determined the N-terminal amino acid sequence of Fbh1. We also synthesized and cloned the double-stranded cDNA corresponding to the full-length mRNA of Fbh1 to use it as a probe in both Northern blot and in situ hybridization experiments. Fbh1 mRNA is detectable in specific parts of the fruit body, and it is absent in other developmental stages.

Clinical and magnetic resonance imaging correlation in acute spinal cord injury

The aim of this study was to correlate traumatic spinal cord injury (SCI) patient's outcome with magnetic resonance imaging (MRI) performed within the first 15 days following trauma. We retrospectively analyzed 55 SCI patients. Upon admission, 28 were diagnosed as having a complete SCI (51%), versus 27 with an incomplete SCI (49%). All of the patients with a normal pattern on MRI (four cases), had an incomplete SCI, whereas all patients (15 cases) presenting with a hemorrhage pattern (Type 1) had a complete SCI (P = 0.0001). Fourteen of the 15 individuals (93.4%) with the edema pattern (Type II) had an incomplete SCI (P = 0.001), while the other patient had neurological deterioration, and a syrinx was noted 2 years later (6.6%). Among the 10 individuals showing a contusion pattern (Type III), seven were admitted with an incomplete SCI (70%) and three with a complete SCI (30%). The compression pattern tends to be associated with a complete SCI in 77.8% (seven of nine patients). All patients with a transection pattern on MRI (two cases) were clinically diagnosed as having a complete SCI. Early functional prognosis may be established on the basis of clinical presentation of SCI and associated MRI. Cord hemorrhage and transection are irreversible, while edema has a potential for neurological recovery. Cord contusion tends to be associated with an incomplete SCI, unlike the compression pattern, in which the prognosis depends on the degree of the initial neurological damage.

[Assessment of the feasibility of a distance medical education program]

BACKGROUND

Continuing medical education is essential to cope with the accelerated evolution of medical knowledge.

AIM

To assess the feasibility of a distance medical education program prepared in a written format.

SUBJECTS AND METHODS

Ninety physicians, aged 25 to 29 years old and with 1 to 4 years of medical practice, working mostly in rural locations, participated in the program. The sending of 10 issues with medical topics was programmed. The topics were selected according to the results of an survey done among physicians of the region. Each issue contained an evaluation that had to be returned to the authors.

RESULTS

Eighty two physicians completed the program and 59 returned the evaluations. The mean obtained score in the cognitive evaluation was 80 +/- 6 points (range 68 to 97 points) of a scale from 0 to 100. The qualitative survey revealed a high degree of approval of the issue's format, contents and evaluation system. The favorable effect on patient's management and on the detection and control of chronic diseases was emphasized.

CONCLUSIONS

This distance medical education program had a good receipt and compliance among physicians and contributed to continuing medical training.

Nasal inflammatory responses in children exposed to a polluted urban atmosphere

Southwest Metropolitan Mexico City (SWMMC) preadolescent children have been exposed to a highly polluted urban atmosphere most of their lives. The main objective of this study was to determine by nasal lavage (NAL) the acute inflammatory nasal influx elicited in these children upon exposure to three different polluted days. Ozone, the main criteria pollutant for SWMMC, varied both in the number of hours above the National Ambient Air Quality Standard (NAAQS), which is 0.12 ppm as a 1-h maximum concentration not to be exceeded more than once per year, and in the maximal concentrations in the preceding three NAL sampling dates. Nasal neutrophilic influx, the surface expression of the B2 integrin CD11b on the nasal polymorphonuclear leukocytes (PMNs), rhinoscopic findings, respiratory symptoms, and nasal cytologies were evaluated in the 38 exposed children and in the 28 control children living in a nonpolluted Pacific coast port. SWMMC children had an average daily outdoor exposure of 7.7 h and complained of nasal mucus secretion, epistaxis, intermittent nasal obstruction, diurnal cough episodes, and chest discomfort. Nasal mucosal atrophy by rhinoscopy was present in 37/38, and all children had an abnormal nasal cytology. Exposed children had significantly higher nasal PMNs and nasal PMN-CD11b expression than controls. PMN median values in exposed children were higher than controls on all sampling dates (November 12, p < .001; November 17, p < .001; and November 24, p < .00001). Interestingly, a lower nasal neutrophilic response (p < .0004) was recorded in the SWMMC children 18 h after exposure to the highest O3 concentrations (up to 0.307 ppm) and the largest number of hours with O3 > 0.12 ppm (7 h). The question of a competing inflammatory response at the bronchioalveolar level with structural damage is raised. These NAL findings underscore the need to restrict outdoor activity in SWMMC children during the months of greater potential exposure to ozone.

[Evaluation of a computer-based independent study program applied to fourth year medical students]

The aim of this work was to assess an independent study program on hypertension using a computer multimedia program developed by the authors. Twenty-four randomly chosen students participated in the program and 76 students that continued to attend to classical lectures were used as controls. At the end of the program, a cognitive test with 40 multiple choice questions and an opinion questionnaire were applied. The experimental group had higher grades in the test than controls (71.4 and 64.6% respectively p < 0.001) and a highly favourable opinion of the program. It is concluded that computer based teaching programs are a useful and feasible alternative to lectures.

[Results of a problem-based learning experience applied to first year medical students]

The aim of this work was to study the feasibility of applying problem-based learning methodologies to first year medical students. During 1992, they participated in tutorial groups composed by ten students, that undertook the study of three clinical problems from a biological, psychological and social perspective. Cognitive tests that included multiple choice and developmental questions were used for assessment. An anonymous enquiry about the students opinion towards the educational experience was also applied. Students achieved 76% of the predetermined goals for each problem. Scoring was better for developmental than multiple choice questions. The experience had a great acceptance among students, that considered as positive features the learning motivation, the stimulus for active participation, the achievement of personal expectancies, the integration of knowledge areas and the encouragement of team work and information seeking.

[Ureteroscopy. Our results and complications]

From November, 1987 to December, 1990, 399 cases of ureteral calculi were treated by rigid ureteroscopy (URS). Our success and complication rates are presented. Of these, 99 (25%) had a calculus in the pelvis (78/99), iliac (15/99) or lumbar (6/99) ureter, and 300 (75%) had Sandstrasse in the distal ureter. The cases with Sandstrasse were submitted to ureteroscopy within the first 48-72 hours to remove the ureteral obstruction, prevent hydronephrosis or sepsis and to expedite treatment. If symptomatic, obstructive and/or 7 mm or more in diameter, a nephrostomy tube was placed first whenever there was sepsis [23/300 (7%) of those with Sandstrasse and 3/99 (3%) of those with a ureteral calculus] or marked dilatation of the renal cavities [29/300 (9%) and 6/99 (6%), respectively]. The success rate was 93% for the cases with Sandstrasse versus 85% for those with a ureteral calculus, and the complication rates were 5.7% versus 9%, respectively. The foregoing results confirm the high success rate and scant morbidity of ureteroscopy in the treatment of ureteral calculus and Sandstrasse.

[A urinary outbreak of Acinetobacter baumanii in a spinal cord injury unit]

From January 1990 to April 1992, 114 urinary strains of Acinetobacter baumanii were isolated in 57 patients with traumatic spinal cord [correction of medular] injury. The strains were characterized by having all of them the same biochemical identification, except for citrate, maltose and tryptophan-desaminase. Until December 1990, (5 strains) were resistant to all antibiotics, except to tobramicine, amikacine, cotrimoxazol and imipenem (6.3%, 33.9%, 26.7% and 0% of resistances, respectively); since January 1991, (99 strains) became resistant to all of them, except to imipenem. 39.5% of AB were isolated in pure cultures, 46% of them with pyuria. Between February 1991 and January 1992, we observed the highest number of affected patients, although without seasonal predominance. We observed as well a higher incidence among males (46 males, 11 females). 80% of them carried a permanent probe. Only 6 patients presented clinical signs directly related to AB. The environmental study could not demonstrate any source of contagion or transmission mechanism.

Enzyme activation by denaturants in organic solvent systems with a low water content

The effect of urea and guanidine hydrochloride (GdmCl) on the activity of heart lactate dehydrogenase, glycerol-3-phosphate dehydrogenase, hexokinase, inorganic pyrophosphatase, and glyceraldehyde-3-phosphate dehydrogenase was studied in low-water systems. Most of the experiments were made in a system formed with toluene, phospholipids, Triton X-100, and water in a range that varied over 1.0-6.5% (by vol.) [Garza-Ramos, G., Darszon, A., Tuena de Gómez-Puyou, M. & Gómez-Puyou, A. (1990) Biochemistry 29, 751-757]. In such conditions at saturating substrate concentrations, the activity of the enzymes was more than 10 times lower than in all-water media. However the activity of the first four aforementioned enzymes was increased between 4 and 20 times by the denaturants. The most marked activating effect was found with lactate dehydrogenase; with 3.8% (by vol.) water maximal activation was observed with 1.5 M GdmCl (about 20-fold); 4 M urea activated, but to a lower extent. Activation by guanidine thiocyanate was lower than with GdmCl. The activating and inactivating effects of GdmCl on lactate dehydrogenase depended on the amount of water; as the amount of water was increased from 2.0% to 6.0% (by vol.), activation and inactivation took place with progressively lower GdmCl concentrations. When activity was measured as a function of the volume of 1.5 M GdmCl solution, a bell-shaped activation curve was observed. In a low-water system formed with n-octane, hexanol, cetyltrimethylammonium bromide and 3.0% water, a similar activation of lactate dehydrogenase by GdmCl and urea was observed. The water solubility diagrams were modified by GdmCl and urea, and this could reflect on enzyme activity. However, from a comparison of denaturant concentrations on the activity of the enzymes studied, it would seem that, independently of their effect on the characteristics of the low-water systems, denaturants bring about activation through their known mechanism of action on the protein. It is suggested that the effect of denaturants is due to the release of constraints in enzyme catalysis imposed by a low-water environment.

Activity of heart and muscle lactate dehydrogenases in all-aqueous systems and in organic solvents with low amounts of water. Effect of guanidine chloride

The effect of urea and guanidine hydrochloride (GdmCl) on the activity of lactate dehydrogenases from heart and muscle was studied in standard water mixtures and in reverse micelles formed with n-octane, hexanol, cetyltrimethylammonium bromide and water in a concentration that ranged over 2.5-6.0% (by vol.). In all water mixtures GdmCl (0.15-0.75 M) and urea (0.5-3.0 M) inhibited the activity of the enzymes at non-saturating pyruvate concentrations. At concentrations of pyruvate that proved inhibitory for enzyme activity due to the formation of a ternary enzyme-NAD-pyruvate complex, GdmCl and urea increased the activity of the enzymes. This increase correlated with a decrease of the ternary complex, as evidenced by its absorbance at 320-325 nm. In the low-water system it was found that: (a) at all concentrations of pyruvate tested (0.74-30 mM), GdmCl enhanced the activity of the heart enzyme to a similar extent; (b) in the muscle enzyme, GdmCl inhibited or increased the activity through a process that depended on the concentration of pyruvate and GdmCl; (c) under optimal conditions, the activation by GdmCl was about two times lower in the muscle than in the heart enzyme, although in all-water media the activity of the muscle enzyme was twice as high. The expression of lactate dehydrogenase activity in the low-water system was higher with the heart than with the muscle enzyme compared to their activities in all-water media (about 260 and 600 mumol min-1 mg-1 in the heart and muscle enzymes respectively). Apparently for catalysis, the water requirement in the heart enzyme is lower than in the muscle enzyme. It is likely that the different response of the two enzymes to solvent is due to their distinct structural features.

Mating system in rye: variability in relation to the population and plant density

The amount of outcrossing was estimated using seven enzyme loci assayed in seven populations of rye (Secale cereale L.). Single-locus outcrossing values fluctuated widely from locus to locus in each population. The weighted mean single-locus estimates ranged from 0.716 to 0.946, and multilocus estimates ranged from 0.701 to 0.910. The analysis showed that self-pollination occurred in the rye populations, and, as a result of selfing, populations contained homozygotes in excess of random mating expectations at the seedling stage of development. Low plant density, which causes low pollen density during fertilization, seems to weaken the self-incompatibility system; at low plant density, the outcrossing estimate was significantly lower than was obtained at high plant density.

The use of functional analysis of the ribosome as a tool to determine archaebacterial phylogeny

Forty different antibiotics with diverse kingdom and functional specificities were used to measure the functional characteristics of the archaebacterial translation apparatus. The resulting inhibitory curves, which are characteristic of the cell-free system analyzed, were transformed into quantitative values that were used to cluster the different archaebacteria analyzed. This cluster resembles the phylogenetic tree generated by 16S rRNA sequence comparisons. These results strongly suggest that functional analysis of an appropriate evolutionary clock, such as the ribosome, is of intrinsic phylogenetic value. More importantly, they indicate that the study of the nexus between genotypic and phenotypic (functional) information may shed considerable light on the evolution of the protein synthetic machinery.