Strain-induced polarization rotation in epitaxial (001) BiFeO3 thin films

Direct measurement of the remanent polarization of high quality (001)-oriented epitaxial BiFeO3 thin films shows a strong strain dependence, even larger than conventional (001)-oriented PbTiO3 films. Thermodynamic analysis reveals that a strain-induced polarization rotation mechanism is responsible for the large change in the out-of-plane polarization of (001) BiFeO3 with biaxial strain while the spontaneous polarization itself remains almost constant.

Clinical evolution of heart transplantation in patients with previous valvular cardiomyopathy

OBJECTIVE

Heart transplantation (HT) due to valvular cardiomyopathy is rare, namely, about 3% of cases in the Registry of the International Society for Heart and Lung Transplantation (ISHLT). Usually, these patients present some risk factors such as previous valvular operations and pulmonary hypertension. Since there are few studies in the literature, we retrospectively analyzed our early and long-term results.

MATERIALS AND METHODS

We studied our experience in 22 HT cases for valvular cardiomyopathy (9.3% of our total experience), namely, 12 men and 10 women, of overall mean age of 52.6 +/- 10 years. Five patients had mitral; 8, aortic; and 1, tricuspid valve disease; 7 had double valve disease and 1, triple valve disease. Nineteen patients (87%) had been operated previously between 1 and 4 times. The mean ejection fraction was 23% +/- 7.3% and the mean New York Heart Association (NYHA) functional class was 3.7. Fifty-three percent of the patients had pulmonary hypertension. Two patients were operated as an emergency "O." We used the standard HT technique.

RESULTS

Four patients (18%) were reoperated due to hemorrhage. The hospital mortality was 2 cases (9%). Another patients (9%) died on follow-up due to cardiac allograft vasculopathy. All surviving patients have been followed to the end of 2006. The mean follow-up has been 72 +/- 53 months. They are functional class I or II.

CONCLUSIONS

HT for this indication was more frequent in our experience than in the Registry of the ISHLT. The immediate and long-term results were good, with an 82% mean survival at 6 years. HT can be a good treatment for patients with valvular cardiomyopathy and bad ventricular function and/or multiple valvular reoperations.

S-adenosyl methionine: A connection between nutritional and genetic risk factors for neurodegeneration in Alzheimer's disease

Clinical manifestation of Alzheimer's disease may depend upon interaction among its risk factors. Apolipoprotein E-deficient mice undergo oxidative damage and cognitive impairment when deprived of folate. We demonstrate herein that these mice were depleted in the methyl donor S-adenosyl methionine (SAM), which inhibited glutathione S-transferase, since this enzyme requires methylation of oxidative species prior to glutathione-dependent reduction. Dietary supplementation with SAM alleviated neuropathology. Since SAM deficiency promotes presenilin-1 overexpression, which increases gamma-secretase expression and Abeta generation, these findings directly link nutritional deficiency and genetic risk factors, and support supplementation with SAM for Alzheimer's therapy.

A randomised controlled trial of postural interventions for prevention of musculoskeletal symptoms among computer users

AIMS

To examine the effect of two workstation and postural interventions on the incidence of musculoskeletal symptoms among computer users.

METHODS

Randomised controlled trial of two distinct workstation and postural interventions (an alternate intervention and a conventional intervention) among 376 persons using computer keyboards for more than 15 hours per week. The incidence of neck/shoulder symptoms and hand/arm symptoms during six months of follow up among individuals in the intervention groups was compared to the incidence in computer users who did not receive an intervention (comparison group). For individuals in the intervention groups, study staff adjusted workstations, where possible, and trained individuals to assume the intervention postures. Individuals reported musculoskeletal symptoms in a weekly diary. Participants who reported discomfort intensity of 6 or greater on a 0-10 visual analogue scale or who reported musculoskeletal symptoms requiring use of analgesic medication were considered symptomatic.

RESULTS

There were no significant differences in the incidence of musculoskeletal symptoms among the three intervention groups. Twenty two (18.5%) participants in the alternate intervention group, 25 (20.2%) in the conventional intervention group, and 25 (21.7%) in the comparison group developed incident arm or hand symptoms. Thirty eight (33.3%) participants in the alternate intervention group, 36 (31.0%) in the conventional intervention group, and 33 (30.3%) in the comparison group developed incident neck or shoulder symptoms. Compliance with all components of the intervention was attained for only 25-38% of individuals, due mainly to the inflexibility of workstation configurations.

CONCLUSIONS

This study provides evidence that two specific workplace postural interventions are unlikely to reduce the risk of upper extremity musculoskeletal symptoms among computer users.

Genetic determinants of Venezuelan equine encephalitis emergence

Following a period of inactivity from 1973-1991, Venezuelan equine encephalitis (VEE) reemerged during the past decade in South America and Mexico. Experimental studies of VEE virus (VEEV) infection of horses with virus strains isolated during these outbreaks have revealed considerable variation in the ability of equine-virulent, epizootic strains to exploit horses as efficient amplification hosts. Subtype IC strains from recent outbreaks in Venezuela and Colombia amplify efficiently in equines, with a correlation between maximum viremia titers and the extent of the outbreak from which the virus strain was isolated. Studies of enzootic VEEV strains that are believed to represent progenitors of the epizootic subtypes support the hypothesis that adaptation to efficient replication in equines is a major determinant of emergence and the ability of VEEV to spread geographically. Correlations between the ability of enzootic and epizootic VEEV strains to infect abundant, equiphilic mosquitoes, and the location and extent of these outbreaks, also suggest that specific adaptation to Ochlerotatus taeniorhynchus mosquitoes is a determinant of some but not all emergence events. Genetic studies imply that mutations in the E2 envelope glycoprotein gene are major determinants of adaptation to both equines and mosquito vectors.

Dietary supplementation with apple juice concentrate alleviates the compensatory increase in glutathione synthase transcription and activity that accompanies dietary- and genetically-induced oxidative stress

Increased oxidative stress, which can arise from dietary, environmental and/or genetic sources, contributes to the decline in cognitive performance during normal aging and in neurodegenerative conditions such as Alzheimer's disease. Supplementation with fruits and vegetables that are high in antioxidant potential can compensate for dietary and/or genetic deficiencies that promote increased oxidative stress. We have recently demonstrated that apple juice concentrate (AJC) prevents the increase in oxidative damage to brain tissue and decline in cognitive performance observed when transgenic mice lacking apolipoprotein E (ApoE-/-) are maintained on a vitamin-deficient diet and challenged with excess iron (included in the diet as a pro-oxidant). However, the mechanism by which AJC provided neuroprotection was not conclusively determined. Herein, we demonstrate that supplementation with AJC also prevents the compensatory increases in glutathione synthase transcription and activity that otherwise accompany maintenance of ApoE-/- mice on this vitamin-free diet in the presence of iron. Inclusion of the equivalent composition and concentration of sugars of AJC did not prevent these increases. These findings provide further evidence that the antioxidant potential of AJC can compensate for dietary and genetic deficiencies that otherwise promote neurodegeneration.

Efficacy of vitamin E, phosphatidyl choline and pyruvate on Abeta neurotoxicity in culture

Oxidative stress is a pivotal factor in neuronal degeneration including that induced by exposure to amyloid-beta (Abeta). Treatment with antioxidants such as vitamin E can alleviate Abeta neurotoxicity. However, vitamin E was only marginally effective in clinical trials in Alzheimer's disease. Recent studies indicate that treatment with vitamin E (as a-tocopherol), sodium pyruvate and phosphatidyl choline (PC) is more effective than vitamin E alone against neuronal oxidative stress. We demonstrate herein that treatment of cultured murine cortical neurons with these 3 agents is also more effective than vitamin E alone against Abeta neurotoxicity as assayed by generation of reactive oxygen species and increased levels of phospho-isoforms of the microtubule-associated protein tau. These data underscore the potential efficacy of a combinatorial neuroprotective formulation against Abeta neurotoxicity.

[Optimization of an individualized LASIK surgery. Geometric ray tracing model]

PURPOSE

To develop an objective calculation method that is able to provide a customized surgical correction that allows the patient to reach the emmetropia and the maximum visual acuity after the surgery.

METHODS

The study included 187 eyes with myopia or myopic astigmatism that underwent LASIK. The optical characterization of each eye was developed by a complete theoretical model based in Le Grand eye, in which the measured values of radii and thicknesses of the different surfaces have been substituted. By means of a geometric ray tracing, the surgery has been simulated by changing the anterior corneal radius and the corneal thickness within the optical zone to obtain its influence in the ocular image and the visual acuity. We considered the surgery to be <<satisfactory>> when the residual equivalent refraction was between 0 and +0.5 D.

RESULTS

An interval for the final corneal radius is proposed for each eye in order to reach the best visual acuity (optimal interval). The position of the post-surgical radius in this interval has been related with the success of the surgical process.

CONCLUSIONS

An objective method for LASIK has been proposed: i) it calculates a personalized surgical plan that allows the patient to reach the best visual quality, and ii) it can be used as a reference by the surgeon to design his nomogram and to decrease his learning curve.

Initiator recognition in a primitive eukaryote: IBP39, an initiator-binding protein from Trichomonas vaginalis

While considerable progress has been made in understanding the mechanisms of transcription in higher eukaryotes, transcription in single-celled, primitive eukaryotes remains poorly understood. Promoters of protein-encoding genes in the parasitic protist Trichomonas vaginalis, which represents one of the deepest-branching eukaryotic lineages, have a bipartite structure with gene-specific regulatory elements and a conserved core promoter encompassing the transcription start site. Core promoters in T. vaginalis appear to consist solely of a highly conserved initiator (Inr) element that is both a structural and a functional homologue of its metazoan counterpart. Using DNA affinity chromatography, we have isolated an Inr-binding protein from T. vaginalis. Cloning of the gene encoding the Inr binding protein identified a novel 39-kDa protein (IBP39). We show that IBP39 binds to both double and single Inr motifs found in T. vaginalis genes and that binding requires the conserved nucleotides necessary for Inr function in vivo. Analyses of the cloned IBP39 gene revealed no homology at the protein sequence level with identified proteins in other organisms or the presence of known DNA-binding domains. The relationship between IBP39 and Inr-binding proteins in metazoa presents interesting evolutionary questions.

Familial intrahepatic cholestasis 1: studies of localization and function

Mutations in the FIC1 gene constitute the molecular defect in familial intrahepatic cholestasis I (Fic1 [Byler's disease]) and benign recurrent intrahepatic cholestasis. This report describes the localization of Fic1 in rat liver and intestine, as well as biochemical and transfection studies that support its function as an energy-dependent aminophospholipid translocase. Immunocytochemistry of rat liver and immunoblotting of membrane fractions localized Fic1 to the canalicular, but not basolateral, plasma membrane domain. In the small intestine, Fic1 was localized to the apical membrane of epithelial cells. The distribution of Fic1 in liver plasma membrane fractions from control and taurocholate-treated rats correlated positively with adenosine triphosphate (ATP)-dependent aminophospholipid (phosphatidyl-serine) translocase activity. In canalicular membrane vesicles, translocase activity had an initial velocity of 3.3 nmol phosphatidylserine (PS) translocated per milligram of protein per minute and a K(m) (ATP) = 1.2 mmol/L; was inhibited by vanadate, N-ethylmaleimide, sodium azide, and calcium; and was unidirectional (i.e., from the outer to the inner canalicular plasma membrane leaflet). Transient transfection of CHOK1 cells with FIC1 cDNA resulted in appearance of FIC1 in membrane preparations and energy-dependent PS translocation in cells. These studies indicate that FIC1 is a canalicular P-type ATPase that participates in maintaining the distribution of aminophospholipids between the inner and outer leaflets of the plasma membrane. How this process produces cholestasis is under study.

Homocysteine potentiates beta-amyloid neurotoxicity: role of oxidative stress

The cause of neuronal degeneration in Alzheimer's disease (AD) has not been completely clarified, but has been variously attributed to increases in cytosolic calcium and increased generation of reactive oxygen species (ROS). The beta-amyloid fragment (Abeta) of the amyloid precursor protein induces calcium influx, ROS and apoptosis. Homocysteine (HC), a neurotoxic amino acid that accumulates in neurological disorders including AD, also induces calcium influx and oxidative stress, which has been shown to enhance neuronal excitotoxicity, leading to apoptosis. We examined the possibility that HC may augment Abeta neurotoxicity. HC potentiated the Abeta-induced increase in cytosolic calcium and apoptosis in differentiated SH-SY-5Y human neuroblastoma cells. The antioxidant vitamin E and the glutathione precursor N-acetyl-L-cysteine blocked apoptosis following cotreatment with HC and Abeta, indicating that apoptosis is associated with oxidative stress. These findings underscore that moderate accumulation of excitotoxins at concentrations that alone do not appear to initiate adverse events may enhance the effects of other factors known to cause neurodegeneration such as Abeta.

Geometric Ray Tracing Analysis of Visual Acuity After Laser in situ Keratomileusis

PURPOSE

Using a geometric ray tracing model, we explain the increase in visual acuity observed in myopic patients after laser in situ keratomileusis (LASIK).

METHODS

This study included 37 eyes of 23 patients who underwent LASIK. All patients had myopia and a spectacle-corrected visual acuity of 0.95 or worse. Clinical tests included biometry, corneal topography, pachymetry, and refraction (with and without cycloplegia). Calculations were made by tracing rays through all the refractive surfaces of the eye based on a Le Grand-type theoretical model of the whole eye.

RESULTS

Comparison of spectacle-corrected visual acuity of the eye before surgery, the size of the blur circle calculated by ray tracing, and the magnification for the ocular system facilitated a numerical criterion to assess visual acuity by geometric calculation. This criterion was applied to myopic eyes that underwent LASIK, and the maximum increase in spectacle-corrected visual acuity was predicted. An actual increase in visual acuity of approximately 40% of the predicted maximum was observed in patients.

CONCLUSIONS

With geometric ray tracing, it was possible not only to obtain an estimate of the visual acuity before LASIK but also to assess the value of the maximum and probable increases in visual acuity after LASIK.

Unexpected Corneal Flattening After Laser in situ Keratomileusis

PURPOSE

To perform a statistical study of the variation (flattening) from the surgical radius (sculpted in the corneal stroma) to the final radius of the first surface of the cornea after laser in situ keratomileusis (LASIK) for correction of myopia.

METHODS

The study included 387 eyes with myopia or myopic astigmatism that underwent LASIK using the Nidek EC-5000 excimer laser. Mean age was 34 years (range, 19 to 75 yr). Mean myopia was -5.19 D (range, 0 to -19.00 D) and mean astigmatism was -1.22 D (range, 0 to -5.00 D). The flattening coefficient was defined as: (f) = (Rpost-Rs)/Rs where Rpost. was the corneal radius after surgery (topography performed 1 month after surgery) and Rs was the surgical radius sculpted in the stroma. Mean values and standard deviations of the flattening coefficient were calculated for the 387 eyes for four myopic ranges (0 to -3.00 D, -3.00 to -6.00 D, -6.00 to -9.00 D, and more than -9.00 D), and for three astigmatic ranges (0, -0.25 to -2.00 D, and more than -2.00 D). The correlations between the flattening coefficient and several preoperative ocular variables were obtained.

RESULTS

A linear combination of quasi-independent ocular variables (age, anterior corneal radius, corneal thickness, sphere and cylinder) was found in order to maximize the correlation with the flattening for every range. Values for the correlations between 0.4 to 0.5 were obtained.

CONCLUSION

The flattening phenomenon was characterized by a flattening coefficient (f).

Actin induction during PMA and cAMP-dependent signal pathway activation in Entamoeba histolytica trophozoites

Activation of PKC or cAMP-dependent signalling pathways in Entamoeba histolytica triggers the phosphorylation of proteins involved in actin rearrangements necessary for adhesion and locomotion. Analogous motifs to SRE and CRE sequences--known to respond to PMA and cAMP--were identified within the 5' regulatory region (5'RR) of one of the parasite actin genes. These sequences could be involved in the actin transcriptional upregulation reported during signalling. To test this hypothesis, a plasmid containing the 5'RR of the actin gene fused to the bacterial neomycin gene (neo) was used for stable transfection. Expression of neo and endogenous actin was measured after stimulation of transfected amoebae by PMA and dcAMP. It was found that both compounds induced neo and actin expression and showed a co-operative effect in the induction of neo. Induction by PMA or dcAMP failed if the directing amoebic 5'RR lacked SRE and CRE motifs. Transfection of amoebae with plasmid constructs, containing either progressive deletions of the actin 5'RR or site-directed mutations of the SRE and CRE-like motifs, corroborated that these sequences and a co-ordinated participation of PKC- and PKA-activated transcription factors are responsible for the increments in neo and actin mRNAs. In vivo, these PMA and cAMP-response elements could play an important role in regulating actin expression and organization in signalling processes activated during tissue invasion.

[Influence of helminthic infections and nutritional status on immune response in Venezuelan children]

We investigated the influence of nutritional status, as determined from anthropometric measurement, and of helminthic infections on the immune response of children of low socioeconomic status in two rural communities in Venezuela: El Cardón in the state of Nueva Esparta and San Daniel in the state of Miranda. A total of 125 boys and girls between 2 and 15 years old participated in the study. Their socioeconomic stratum was determined by a modified Graffar method. A physical examination was performed, as was also an anthropometric evaluation that took into account three indicators--weight-for-height, weight-for-age, and height-for-age--according to parameters established by the World Health Organization. Other examinations included feces, secretory IgA in saliva, total serum IgE, and anti-Ascaris-specific immunoglobulins. The children in both of the communities were in strata IV and V of the of Graffar scale, with a significantly greater number of stratum V inhabitants in San Daniel (P < 0.001). The results suggest that exposure level and individual susceptibility to the parasites are determining factors in parasitic infection and immune system behavior. The intensity of the parasitic burden plays an important role in stimulating polyclonal IgE, which diminishes the effectiveness of the specific response to those infections. On the other hand, nutritional deficiencies could change the immune mechanisms of the mucous membranes, negatively influence the synthesis of secretory IgA, and stimulate the production of polyclonal IgE. Poor sanitary and socioeconomic conditions promote more exposure to gastrointestinal parasites and a deficient nutritional status, which modulates the immune response and affects serum IgE and secretory IgA production mechanisms.

Computer users' postures and associations with workstation characteristics

This investigation tested the hypotheses that (1) physical workstation dimensions are important determinants of operator posture, (2) specific workstation characteristics systematically affect worker posture, and (3) computer operators assume "neutral" upper limb postures while keying. Operator head, neck, and upper extremity posture and selected workstation dimensions and characteristics were measured among 379 computer users. Operator postures were measured with manual goniometers, workstation characteristics were evaluated by observation, and workstation dimensions by direct measurement. Considerably greater variability in all postures was observed than was expected from application of basic geometric principles to measured workstation dimensions. Few strong correlations were observed between worker posture and workstation physical dimensions; findings suggest that preference is given to keyboard placement with respect to the eyes (r = 0.60 for association between keyboard height and seated elbow height) compared with monitor placement with respect to the eyes (r = 0.18 for association between monitor height and seated eye height). Wrist extension was weakly correlated with keyboard height (r = -0.24) and virtually not at all with keyboard thickness (r = 0.07). Use of a wrist rest was associated with decreased wrist flexion (21.9 versus 25.1 degrees, p < 0.01). Participants who had easily adjustable chairs had essentially the same neck and upper limb postures as did those with nonadjustable chairs. Sixty-one percent of computer operators were observed in nonneutral shoulder postures and 41% in nonneutral wrist postures. Findings suggest that (1) workstation dimensions are not strong determinants of at least several neck and upper extremity postures among computer operators, (2) only some workstation characteristics affect posture, and (3) contrary to common recommendations, a large proportion of computer users do not work in so-called neutral postures.

GI endoscopic reprocessing practices in the United States

BACKGROUND

Patient infection from contaminated gastrointestinal (GI) endoscopes can generally be attributed to failure to follow appropriate reprocessing guidelines. Recently, the Food and Drug Administration recommended a 45-minute exposure of GI endoscopes to 2.4% glutaraldehyde solutions heated to 25 degrees C. Simultaneously, the American Society for Gastrointestinal Endoscopy (ASGE), the American Gastroenterological Association, and the Society of Gastroenterology Nurses and Associates endorsed a reprocessing guideline that emphasized manual precleaning and recommended a 20-minute exposure to a 2.4% glutaraldehyde solution at room temperature. Since then, little information has become available regarding actual reprocessing practices in the United States.

METHODS

A previously developed questionnaire regarding endoscopic disinfection practices was mailed to randomly selected members of the ASGE.

RESULTS

The survey was sent to 730 members and 294 responded (40.3%). Appropriate manual cleaning (suctioning detergent through the accessory channel and brushing the channel and valves) is performed by 90.7% of respondents; 69.9% then use automated reprocessors for disinfection or sterilization. Glutaraldehyde is the most widely used chemical disinfectant; 85.3% use glutaraldehyde as one of their primary disinfectants. The most commonly used disinfection time with 2.4% glutaraldehyde is 20 minutes (83.9%) followed by 45 minutes (11.4%). Only 23.8% of users of 2.4% glutaraldehyde heat their solution; 59.6% of centers test disinfectant concentration daily or more frequently; 74.0% sterilize nondisposable forceps before use; 29.2% of centers re-use disposable endoscopic accessories (which are more frequently disinfected rather than sterilized). Twelve respondents reported cases of endoscopic cross infection.

CONCLUSIONS

A significant minority of endoscopy centers still do not completely conform to recent ASGE, American Gastroenterological Association, and the Society of Gastroenterology Nurses and Associates guidelines on disinfection, and they may not be appropriately disinfecting GI endoscopes. Rigid adherence to recommended guidelines is strongly encouraged to ensure patient safety.

Protective effects of the flavonoid mixture, silymarin, on fetal rat brain and liver

We investigated the possibility that the flavonoid mixture, silymarin (SY), administered as the compound Silymarin Phytosome (PHYTO), could protect the fetus from maternally ingested EtOH. Seventy-six female rats were randomly assigned to one of seven groups: pair-fed control; chow fed control; EtOH; and four groups receiving EtOH and PHYTO in varying dosages. All groups except the chow-fed control were maintained on a liquid diet. On day 1 of pregnancy the dams began the treatment protocol. On day 21 of pregnancy the rats were sacrificed and the fetuses removed. Gamma glutamyl transpeptidase (GGTP) activity was determined for liver and brain tissue from both the fetuses and the dams. GGTP activity in the EtOH/silymarin treatment groups did not differ significantly from that observed for the pair-fed control group. The observed GGTP activity levels for the EtOH-only group were significantly higher than those attained by the pair-fed control group. Although GGTP activity did not vary significantly with the quantity of PHYTO administered, as PHYTO dose was increased, GGTP activity decreased.

[Quality of life and mortality of patients in intensive care. Indices of quality of life]

INTRODUCTION

At present there is no single practical standardized scale for measuring quality of life (QL). Any proposal should include the patient's physical impairment, level of independence, and subjective perception of happiness. We combined three previously published scales to define a quality of life index (QLI) that we propose as a standard quantitative instrument. The applicability and usefulness of QLI for the measurement of the level of deterioration of patients after admission to an intensive care unit (ICU) was examined. We prospectively evaluated QL before patient admission to determine if it influences mortality, as well as long-term changes in the QL and the factors conditioning te deterioration of patients released from the UCI as evaluated by QL indicators.

MATERIAL AND METHODS

To calculate QLI, we combined the Karnofsky scale, daily life activities index, and the perception of quality of life scale. The resulting percentage (QLI) was used to evaluate 536 patients after admission to the ICU and 6 and 12 months after release. QLI was compared with the severity of disease (Apache II), probability of death (MPM), diagnostic group, and socioeconomic variables.

RESULTS

Using multivariate methods, four significant variables related with mortality were identified: Apache II--MPM, duration of the stay in the unit, age, and QLI. Our analysis of long-term deterioration showed that advanced age, high QLI before admission, and the patient's diagnostic group explained the degree of deterioration.

DISCUSSION

QLI was a useful instrument for obtaining a quantitative estimate of the QL of critically ill patients.

Plants from Puerto Rico with anti-Mycobacterium tuberculosis properties

OBJECTIVE

This study assesses the antitubercular potential of natural products obtained from plants reputed to have medicinal properties and collected from the tropical flora of Puerto Rico.

BACKGROUND

The increase in persons infected with Mycobacterium tuberculosis (MTB) the world over and the development of resistance to antibiotics by this microbe and other infectious bacteria has created the need for new drugs to replace those which have lost effectiveness.

METHOD

In Phase I of this study, ethanolic leaf extracts of fifty local plants were submitted to preliminary screening to assess their in vitro Mycobacterium smegmatis inhibitory activity using the Bauer-Kirby disk diffusion method. In Phase II, the definitive screening of the six most promising extracts which inhibited M. smegmatis were assayed for their MTB inhibitory activity using the BACTEC 460 susceptibility test method. The brine shrimp bioassay was used as a toxicity bioassay and the mice inoculation test was used to determine mice tolerance to the effect of the daily intraperitoneal inoculations of the plant extracts.

RESULTS

MTB showed varying degrees of susceptibility to each plant extract. This effect was dependent upon the plant species, dose and time of exposure. Evidence is provided suggesting that: (1) Six crude plant extracts (12%) tested possessed inhibitory capacity at the amount of 500 micrograms per disc; (2) Mammea americana extract yielded the strongest inhibitory effect at 50 micrograms per disc, followed by Marchantia polymorpha, Mangifera indica, Callistemon citrinus, Syzygium jambos and Momordica charantia; (3) the bactericidal inhibitory pattern of MTB growth, exposed to Mammea americana extract, was comparable to streptomycin; and (4) the transitory reduction pattern of MTB growth, produced by Callistemon citrinus, Marchantia polymorpha extracts at 100 micrograms and 250 micrograms, was similar to that of bacteriostatic agents.

CONCLUSION

Of 50 plants screened six extracts tested for their anti-MTB activity yielded positive results with varying degrees of inhibition. Mammea americana showed the greatest inhibitory activity suggesting that certain plant species yield valuable anti-Mycobacterium tuberculosis substances. The procedures employed in this study, including the BACTEC 460 modified method, are useful for in vitro screening of plant extracts with potential antitubercular activity.

[Prone position: postural treatment for patients with adult respiratory distress syndrome. The nurse's point of view]

The prone position is a therapeutic strategy that can be beneficial in the treatment of adult respiratory distress syndrome (ARDS). In order to evaluate the advantages and possible complications associated with this postural change within the context of nursing, we analyzed retrospectively 71 turns carried out in 32 patients who met criteria for ARDS. The patient was turned by a team of 4 or 5 persons following a strict protocol. The PaO2/FIO2 ratio and SatO2 significantly increased in prone position, without any hemodynamic repercussions. No extubation or loss of vascular accesses or drainage tubes occurred. Complications included: facial edema, low-pressure lesions, and regurgitation of enteral nutrition.