Polysorbate 80 improves the adhesion and survival of yogurt starters with cholesterol uptake abilities.

The goal of this study is to improve the adhesion and survival of yogurt bacteria with probiotic traits by using polysorbate 80, a food additive emulsifier commonly found in milk derivative products. Polysorbate 80 was used at 1% (w/v), and its effects on yogurt bacteria's survival under simulated digestive conditions, cholesterol uptake activities, bile salt hydrolase (BSH) activity, and adhesion to HT-29 culture were studied. In the presence of 1% polysorbate 80, both starters demonstrated better cholesterol uptake and BSH activities, as well as higher bacterial survival at pH 2.5, particularly in associated cultures. In the presence of 0.3 % bile or cholic acid, polysorbate 80 reduced the drop in L. bulgaricus's survival load. However, the carbon source had a greater impact on S. thermophilus bile tolerance than the food additive emulsifier. Oleic acid was incorporated into both bacterial membranes when grown in the presence of bile and polysorbate 80, resulting in a higher unsaturated/saturated fatty acid ratio. In the presence of polysorbate 80, S. thermophilus adhered to HT-29 cells 2.3-fold better, while L. bulgaricus's adhesion remained unchanged. We suggest that polysorbate 80 may have a protective effect on cell survival under simulated digestive stress as well as a role in yogurt bacteria adhesion to the intestines, giving these bacteria more opportunities to exert their purported cholesterol-removal activities.

A Unified Framework for Brain Segmentation in MR Images.

Brain MRI segmentation is an important issue for discovering the brain structure and diagnosis of subtle anatomical changes in different brain diseases. However, due to several artifacts brain tissue segmentation remains a challenging task. The aim of this paper is to improve the automatic segmentation of brain into gray matter, white matter, and cerebrospinal fluid in magnetic resonance images (MRI). We proposed an automatic hybrid image segmentation method that integrates the modified statistical expectation-maximization (EM) method and the spatial information combined with support vector machine (SVM). The combined method has more accurate results than what can be achieved with its individual techniques that is demonstrated through experiments on both real data and simulated images. Experiments are carried out on both synthetic and real MRI. The results of proposed technique are evaluated against manual segmentation results and other methods based on real T1-weighted scans from Internet Brain Segmentation Repository (IBSR) and simulated images from BrainWeb. The Kappa index is calculated to assess the performance of the proposed framework relative to the ground truth and expert segmentations. The results demonstrate that the proposed combined method has satisfactory results on both simulated MRI and real brain datasets.

Mosquito vector biting and community protection in a malarious area, siahoo district, hormozgan, iran.

BACKGROUND: Use of bed-net continues to offer potential strategy for malaria prevention in endemic areas. Local communities are indispensable during design and implementation stages. METHODS: A cross-sectional study of 192 randomly selected inhabitants was carried out in malarious zone, Siahoo direstrict, Hormozgan Province, southern Iran. In addition, we monitored human landing periodicity of main malaria vectors and as well as self-protection of inhabitant in the study area for a period of one transmission season between April to October 2006. RESULTS: The biting activities were seen throughout the whole night for three malaria vectors, Anopheles fluviatilis, An. stephensi and An. dthali, and An. fluviatilis exhibiting bimodal peaks, the first at midnight (0:00-1:00) and the other before dawn (5:00-6:00 am) but the maximum biting activity of An. stephensi was occurred at second quarter of night (11:00-12:00 pm). The majority of interviewers (83.3%) knew that malaria was transmitted by mosquitoes and 70.3% of them stated that bed-net is the best control measures. Most subjects (62%) did not have a mosquito net. CONCLUSION: Study subjects were aware of an association between mosquito bite and malaria transmission. Health workers at different levels of the health care delivery system should disseminate relevant information about self-protection to help community members to be involved more in malaria control.

Comparison of functional and radiological outcomes after computer-assisted versus conventional total knee arthroplasty: a matched-control retrospective study.

PURPOSE: To compare the radiological and functional outcomes of patients who underwent either computer-assisted or conventional total knee arthroplasty (TKA). METHODS: Two groups of 50 patients each underwent either computer-assisted or conventional TKA were retrospectively studied. Patients were matched according to body mass index (BMI), gender, and age. Three senior orthopaedic surgeons with comparable experience performed all surgeries, using 3 different prostheses. The surgical approach and peri- and postoperative regimens were the same. The mechanical axis and the tibial and femoral angles were measured using standardised long-leg weight-bearing radiographs. Overall function was assessed using the Short Form-12 (SF-12) and International Knee Society (IKS) scores. RESULTS: No intra-operative technical difficulties were encountered in either group. The computer-assisted group resulted in more consistent and accurate alignments in both the coronal and sagittal planes and better SF-12 and IKS scores. In obese patients (BMI=30 kg/m2 or more), computer-assisted TKA provided better alignment than the conventional technique. CONCLUSION: Computer-assisted TKA improves implant positioning, limb alignment, and overall functional outcome. It may be particularly advantageous for obese patients.

Vocational rehabilitation services for people with multiple sclerosis: what patients want from clinicians and employers.

BACKGROUND: The NSF for Long-term Neurological Conditions highlights the need for vocational rehabilitation services. Although the barriers to work for people with MS (pwMS) have been clearly identified, there has been little research that identifies the type of support required. OBJECTIVE: To identify what pwMS require from a vocational rehabilitation service in terms of content and service delivery. DESIGN OF STUDY: Four focus groups of pwMS, currently in employment, were convened. These were audio-taped and content analysed using a constant comparison method. RESULTS: People with MS identified two key needs; managing performance and managing expectations. Performance difficulties could be managed either by treating symptoms, by changing the environment, or by altering the demands of the job. PwMS highlighted the need for counselling to help them, and advocacy to help their employers have appropriate expectations. CONCLUSION: PwMS need support in the workplace in two distinct ways. First, by managing the interaction between the impairments caused by MS, the physical environment, and the demands imposed by the work. Second, by providing expert knowledge about the employment environment and the needs of employers, an awareness of the relevant legislation and counselling in supporting people to adapt, adjust and resolve complex issues.

Patient-reported Outcome Measures in Multiple Sclerosis.

Patient-reported outcome (PRO) measures are being used more frequently in epidemiological studies, health service research and in clinical trials to evaluate therapeutic interventions from the patient's perspective. In MS, where evaluations of treatments are becoming increasingly important, outcome measures that are rigorous and appropriate to patients are needed. This article examines the value of PRO measures in MS and the criteria of evaluating such measures, and provides a brief description of MS-specific PRO measures that are currently available.

Getting the measure of spasticity in multiple sclerosis: the Multiple Sclerosis Spasticity Scale (MSSS-88).

Spasticity is most commonly defined as an inappropriate, velocity dependent, increase in muscle tonic stretch reflexes, due to the amplified reactivity of motor segments to sensory input. It forms one component of the upper motor neuron syndrome and often leads to muscle stiffness and disability. Spasticity can, therefore, be measured through electrophysiological, biomechanical and clinical evaluation, the last most commonly using the Ashworth scale. None of these techniques incorporate the patient experience of spasticity, nor how it affects people's daily lives. Consequently, we set out to construct a rating scale to quantify the perspectives of the impact of spasticity on people with multiple sclerosis. Qualitative methods (in-depth patient interviews and focus groups, expert opinion and literature review) were used to develop a conceptual framework of spasticity impact, and to generate a pool of items with the potential to convert this framework into a rating scale with multiple dimensions. This item pool was administered, in the form of a questionnaire, to a sample of people with multiple sclerosis and spasticity. Guided by Rasch analysis, we constructed and validated a rating scale for each component of the conceptual framework. Decisions regarding item selection were based on the integration and assimilation of seven specific analyses including clinical meaning, ordering of thresholds, fit statistics and differential item functioning. The qualitative phase (17 patient interviews, 3 focus groups) generated 144 potential scale items and a conceptual model with eight components addressing symptoms (muscle stiffness, pain and discomfort and muscle spasms,), physical impact (activities of daily living, walking and body movements) and psychosocial impact (emotional health, social functioning). The first postal survey was sent to 272 people with multiple sclerosis and had a response rate of 88%. Findings supported the development of scales for each component but demonstrated that five item response options were too many. The 144-item questionnaire, reformatted with four-item response options, was administered with four validating instruments to an independent sample of 259 people with multiple sclerosis (response rate 78%). From the responses, an 88-item instrument with eight subscales was developed that satisfied criteria for reliable and valid measurement. Correlations with other measures were consistent with predictions. The 88-item Multiple Sclerosis Spasticity Scale (MSSS-88) is a reliable and valid, patient-based, interval-level measure of the impact of spasticity in multiple sclerosis. It has the potential to advance outcomes measurement in clinical trials and clinical practice, and provides a new perspective in the clinical evaluation of spasticity.

How responsive is the Multiple Sclerosis Impact Scale (MSIS-29)? A comparison with some other self report scales.

OBJECTIVES: To compare the responsiveness of the Multiple Sclerosis Impact Scale (MSIS-29) with other self report scales in three multiple sclerosis (MS) samples using a range of methods. To estimate the impact on clinical trials of differing scale responsiveness. METHODS: We studied three discrete MS samples: consecutive admissions for rehabilitation; consecutive admissions for steroid treatment of relapses; and a cohort with primary progressive MS (PPMS). All patients completed four scales at two time points: MSIS-29; Short Form 36 (SF-36); Functional Assessment of MS (FAMS); and General Health Questionnaire (GHQ-12). We determined: (1) the responsiveness of each scale in each sample (effect sizes): (2) the relative responsiveness of competing scales within each sample (relative efficiency): (3) the differential responsiveness of competing scales across the three samples (relative precision); and (4) the implications for clinical trials (samples size estimates scales to produce the same effect size). RESULTS: We studied 245 people (64 rehabilitation; 77 steroids; 104 PPMS). The most responsive physical and psychological scales in both rehabilitation and steroids samples were the MSIS-29 physical scale and the GHQ-12. However, the relative ability of different scales to detect change in the two samples was variable. Differing responsiveness implied more than a twofold impact on sample size estimates. CONCLUSIONS: The MSIS-29 was the most responsive physical and second most responsive psychological scale. Scale responsiveness differs notably within and across samples, which affects sample size calculations. Results of clinical trials are scale dependent.

Self-efficacy predicts self-reported health status in multiple sclerosis.

Self-efficacy is a belief that one can competently cope with a challenging situation. If self-efficacy is a strong predictor of health status in multiple sclerosis (MS), it may be an important area to target in clinical practice, as such beliefs may be modifiable. The aim of this study was to examine the predictive value of self-efficacy on self-reported health status in MS. Eighty-nine people with MS completed the Multiple Sclerosis Self-efficacy Scale (MSSE function and control scales), the Multiple Sclerosis Impact Scale (MSIS-29), and the Multiple Sclerosis Walking Scale (MSWS-12) at two time points: 1) admission to an inpatient rehabilitation unit (n = 43) or for steroid treatment for relapses (n = 46); and 2) discharge (rehabilitation group) or six weeks later (steroid group). Multiple regression analyses examined whether baseline and changes in self-efficacy predict changes in self-reported health status. Both baseline and changes in self-efficacy were strong and independent predictors of changes in health status (P-values ranged from 0.025 to < 0.001). That is, pretreatment self-efficacy scores and increases in self-efficacy scores from baseline to follow-up (improvement), were significantly associated with decreases (improvement) in perceived walking ability and physical and psychological impact of MS. The findings suggest that self-efficacy predicts improvement in health status and that self-efficacy would be an important domain to measure and manage actively in education and rehabilitation programs.

Improving the evaluation of therapeutic interventions in multiple sclerosis: development of a patient-based measure of outcome.

OBJECTIVES: To develop a patient-based, disease-specific measure of the health impact of multiple sclerosis (MS) for use in clinical trials and clinical practice. DATA SOURCES: People with MS. Members of the MS Society of Great Britain and Northern Ireland. METHODS: Standard psychometric methods were used to develop the Multiple Sclerosis Impact Scale (MSIS-29) in three stages. Stage 1 (item generation): questionnaire items were generated from 30 patient interviews on the impact of MS on their lives, expert opinion and literature review. Stage 2 (item reduction and scale generation): the questionnaire developed in stage 1 was administered by postal survey to 1530 randomly selected members of the MS Society. Standard item reduction techniques were used to develop a rating scale from the pool of questionnaire items. Stage 3 (psychometric evaluation): the questionnaire was evaluated for data quality, scaling assumptions, acceptability, reliability and validity in a separate postal survey of 1250 MS Society members. Responsiveness was evaluated in 55 people admitted to hospital for rehabilitation and intravenous steroid treatment of MS relapses. RESULTS: Stage 1 resulted in a 129-item questionnaire. Stage 2 resulted in a 29-item rating scale measuring the physical and psychological impact of MS. The MSIS-29 satisfied all recommended psychometric criteria for rigorous measurement. Data quality was excellent: missing data were low, item test-retest reliability was high and scale scores could be generated for over 98% of respondents. Item descriptive statistics, item convergent and discriminant validity, and factor analysis supported summing items to produce two summary scores. MSIS-29 physical and psychological scale scores showed good variability, low floor and ceiling effects, good internal consistency and test-retest reliability. Correlations with other measures and confirmation of hypotheses about group differences provided evidence for the validity of the MSIS-29 as a measure of the physical and psychological impact of multiple sclerosis. Effect sizes provided preliminary evidence for responsiveness. CONCLUSIONS: The 29-item MSIS-29 is a rigorous new measure of the physical and psychological impact of MS. All psychometric criteria were satisfied and there is preliminary evidence of responsiveness. The MSIS-29 is particularly appropriate for use in clinical trials to evaluate therapeutic effectiveness from the patient's perspective. Further critical evaluations of the MSIS-29 completed by people with neurologist-confirmed MS in different settings are suggested. Head-to-head comparisons of the psychometric properties of the MSIS-29 and other outcome measures for MS will help to determine the relative advantages of different instruments so that the choice of measures for studies can be evidence based.

Evidence-based measurement in multiple sclerosis: the psychometric properties of the physical and psychological dimensions of three quality of life rating scales.

The selection of measures of quality of life used in clinical trials of multiple sclerosis (MS) should be evidence-based. Head-to-head comparison of measures facilitates the selection of measures. The aim of the study was to compare the psychometric properties of the physical and psychological dimensions in three measures of quality of life to aid choice of the most appropriate scale for use in clinical trials of MS. One hundred and twenty-one people with MS (rehabilitation = 57; steroids = 64) completed a selection of health measures before and after treatment. The psychometric properties of three measures of physical function (MSIS-29 physical, SF-36 physical functioning, FAMS mobility) and three measures of psychological function (MSIS-29 psychological, SF-36 mental health, FAMS emotional well-being) were compared by examining data quality, scaling assumptions, acceptability, reliability, validity and responsiveness. Physical (0.63-0.71) and psychological (0.70-0.75) scales were substantially correlated indicating they measure related constructs. The MSIS-29 physical and psychological scales satisfied all criteria for internal consistency reliability (physical = 0.91; psychological = 0.89) and validity. The SF-36 physical scale had a notable floor effect (20%). The FAMS mobility scale had lower reliability (alpha = 0.78) compared to other measures. The MSIS-29 physical (effect size = 0.91) and psychological (effect size = 0.62) scales were the most responsive. In these three samples, the MSIS-29 had better measurement properties for combined physical and psychological health than the SF-36 and the FAMS.

Using the SF-36 measure to compare the health impact of multiple sclerosis and Parkinson's disease with normal population health profiles.

OBJECTIVE: To examine the relative impact of two chronic neurological disorders, multiple sclerosis and Parkinson's disease, by comparing patients' scores on the medical outcomes study 36-item short form health survey (SF-36) with the health profile of the United Kingdom population norms. METHODS: 638 people representing the full spectrum of multiple sclerosis and 227 patients with Parkinson's disease were studied. Health status was measured by the SF-36. Scores for the eight health domains were compared after controlling for age, sex, disease duration, mobility, social class, ethnicity, education, marital status, and employment status. RESULTS: People with multiple sclerosis and those with Parkinson's disease had significantly worse health than the general population on all eight domains measured by the SF-36. The relative impact of multiple sclerosis and Parkinson's disease were similar, but multiple sclerosis resulted in poorer scores on physical functioning and better scores in mental health. People with mild multiple sclerosis who walked without an aid also had significantly worse scores in all dimensions than the general UK population. CONCLUSIONS: The results highlight the need for further research into aspects of health measured by the SF-36. Nevertheless, generic measures that are applicable across multiple diseases may fail to address clinically important aspects of the impact of specific disorders.

Measuring the impact of MS on walking ability: the 12-Item MS Walking Scale (MSWS-12).

OBJECTIVE: To develop a patient-based measure of walking ability in MS. METHODS: Twelve items describing the impact of MS on walking (12-Item MS Walking Scale [MSWS-12]) were generated from 30 patient interviews, expert opinion, and literature review. Preliminary psychometric evaluation (data quality, scaling assumptions, acceptability, reliability, validity) was undertaken in the data generated by 602 people from the MS Society membership database. Further psychometric evaluation (including comprehensive validity assessment, responsiveness, and relative efficiency) was conducted in two hospital-based samples: people with primary progressive MS (PPMS; n = 78) and people with relapses admitted for IV steroid treatment (n = 54). RESULTS: In all samples, missing data were low (< or =3.8%), item test-retest reproducibility was high (> or =0.78), scaling assumptions were satisfied, and reliability was high (> or =0.94). Correlations between the MSWS-12 and other scales were consistent with a priori hypotheses. The MSWS-12 (relative efficiency = 1.0) was more responsive than the Functional Assessment of Multiple Sclerosis mobility scale (0.72), the 36-Item Short Form Health Survey physical functioning scale (0.33), the Expanded Disability Status Scale (0.03), the 25-ft Timed Walk Test (0.44), and Guy's Neurologic Disability Scale lower limb disability item (0.10). CONCLUSIONS: The MSWS-12 satisfies standard criteria as a reliable and valid patient-based measure of the impact of MS on walking. In these samples, the MSWS-12 was more responsive than other walking-based scales.

Multiple Sclerosis Impact Scale (MSIS-29): reliability and validity in hospital based samples.

BACKGROUND AND AIM: The psychometric properties of rating scales are sample dependent and need evaluations in different samples. The Multiple Sclerosis Impact Scale (MSIS-29), a new patient based rating scale for multiple sclerosis (MS) was predominantly developed from a community based sample derived from the MS Society. A number of important patient characteristics of this sample remain unknown. The aim of the study was to evaluate five psychometric properties of the MSIS-29 in three hospital based samples: people admitted for rehabilitation, people admitted for intravenous corticosteroid treatment for MS relapses, and people with primary progressive MS. METHODS: People with MS were recruited from the three clinical settings. They completed several health measures. MSIS-29 data were evaluated for data quality, scaling assumptions, acceptability, reliability and validity, and compared with those from a previously reported community based study. RESULTS: A total of 233 people (rehabilitation p=53; corticosteroids p=76; primary progressive p=104) completed questionnaires. In all samples, missing data were low (or=0.91). Correlations between the MSIS-29 and other scales were consistent with a priori hypotheses. Findings were consistent with those from the community samples. CONCLUSIONS: The psychometric properties of the MSIS-29 are consistent across three hospital based samples, and similar to those in the community samples. These findings further support its use as an outcome measure in different clinical settings.

Screening for diabetic retinopathy is well received by patients and may improve self-management intentions.

AIMS: To investigate patients' views of screening for diabetic retinopathy and the effects of the screening process on health beliefs and behavioural intentions. SETTING: A retinal screening clinic at a GP surgery in SW England. METHODS: Questionnaires administered before and immediately after screening by retinal photography. RESULTS: One hundred patients attended (94% of those invited); 12 had Type 1 and 88 Type 2 diabetes. Over 90% found the information, and seeing their retinal photograph, helpful. Sixty-three were found to have no problem and 37 had some type of eye problem detected. Overall, patients rated the news given at screening as better than expected (P < 0.001) and even those found to have problems mostly rated the news as good (P < 0.001). Detection of problems led patients to rate their recent eye health more negatively, but to be less pessimistic about future deterioration (P < 0.01). Patients with diabetes-related eye problems were more likely (P < 0.05) to say that they both should and would make changes to their self-management, but only after controlling for duration of diabetes. Those who had had diabetes longest declared least intention to change. CONCLUSIONS: Screening by retinal photography is acceptable to patients. Results suggest that screening modified health beliefs but had limited effect on behavioural intentions, with patients of longer disease duration being more reluctant to change their self-management. Opportunities during retinal screening for advice on self-management could be more effectively exploited.

The Multiple Sclerosis Impact Scale (MSIS-29): a new patient-based outcome measure.

Changes in health policy have underlined the importance of evidence-based clinical practice and rigorous evaluation of patient-based outcomes. As patient-based outcome measurement is particularly important in treatment trials of multiple sclerosis, a number of disease-specific instruments have been developed recently. One limitation of these instruments is that none was developed using the standard psychometric approach of reducing a large item pool generated from people with multiple sclerosis. Consequently, an outcome measure for clinical trials of multiple sclerosis that is disease specific and combines patient perspective with rigorous psychometric methods will complement existing instruments. The aim of this study was to develop such a measure. Standard psychometric methods were used. A pool of 129 questionnaire items was generated from interviews with 30 people with multiple sclerosis, expert opinion and literature review. The questionnaire was administered by postal survey to 1530 people selected randomly from the Multiple Sclerosis Society membership database. Redundant items and those with limited measurement properties were removed. The remaining items (n = 41) were grouped into scales using factor analysis, and then refined to form the Multiple Sclerosis Impact Scale (MSIS-29), an instrument measuring the physical (20 items) and psychological (nine items) impact of multiple sclerosis. Five psychometric properties of the MSIS-29 (data quality, scaling assumptions, acceptability, reliability and validity) were examined in a separate postal survey of 1250 Multiple Sclerosis Society members. A preliminary responsiveness study of the MSIS-29 was undertaken in 55 people admitted for rehabilitation and intravenous steroid treatment of relapses. The MSIS-29 satisfied all psychometric criteria. Data quality was excellent, missing data were low (maximum 3.9%), item test-re-test reliability was high (r = 0.65-0.90) and scale scores could be generated for >98% of respondents. Item descriptive statistics, item convergent and discriminant validity, and factor analysis indicated that it was legitimate to generate scores for MSIS-29 scales by summing items. MSIS-29 scales showed good variability, small floor and ceiling effects, high internal consistency (Cronbach's alpha

Comparative chromatographic study of modifications of brush-border membrane vesicles induced by an essential fatty acid-deficient diet.

The surface properties of small intestine brush-border membranes (BBMs) were examined by frontal affinity chromatography using three types of unsolubilized ligands: phlorizin polymer, immobilized lectins and linolenic acid bound to agarose gel. BBM vesicles were purified from piglets fed a corn oil diet (control diet) or a hydrogenated coconut oil diet. The second diet was representative of a deficient supply of essential polyunsaturated fatty acid (EPUFA). It induced a marked decrease in 18:2n-6 content in membrane choline phosphoglycerides and ethanolamine phosphoglycerides, whereas 20:3n-9 appeared in each class of phospholipids. Control and EPUFA-deprived BBM vesicles bound to phlorizin polymer, linolenic acid-agarose and wheat germ agglutinin (WGA) gel. In contrast, concanavalin A gel and Lens culinaris A gel exhibited a low binding capacity towards the two types of vesicles. EPUFA deficiency induced a slight decrease in binding on phlorizin polymer and a marked increase in binding on WGA gel, whereas the two types of vesicles similarly bound to linolenic acid-agarose. Desorption of phlorizin polymer-bound membranes was performed using several detergents with special regard to sodium deoxycholate (NaDOC) micelles. Sucrase activity recovery showed that the efficiency of NaDOC desorption was diminished in the case of EPUFA-deprived vesicles. EPUFA-deprived membrane domains involved in the binding would be less sensitive to the detergent attack. This assumption agrees with the putative decrease in membrane fluidity induced by the deficient diet. The possibility that fatty acid compositional changes induced by dietary lipids are extensive enough to alter some chromatographic properties of BBM vesicles is discussed.

Biochemical analysis of vitellogenin from rainbow trout (Salmo gairdneri): fatty acid composition of phospholipids.

Vitellogenin was obtained from three year-old vitellogenic trout. Two procedures of isolation were compared: dialysis against distilled water and ultracentrifugation in the density interval 1.21-1.28 g/ml. Similar patterns were observed by gel filtration and electrophoresis for both preparations of vitellogenin, indicating that electric charge and molecular weight were not modified by either procedure. The apparent Mr of the native form was 560,000 in gel filtration, whereas that of the monomer was estimated as 170,000 by sodium dodecylsulfate-polyacrylamide gel electrophoresis. Minor proteins were also detected (100,000-88,000-78,000). The main components were protein (79%), and lipids (19%), Carbohydrates accounted for 0.3% when protein phosphorus and calcium each represented 0.7% of total weight. Phospholipids (70% of total lipids) mainly consisted of phosphatidylcholine in which n-3 docosahexanenoic acid accounted for one-third of total fatty acids. The results show the high levels of essential fatty acids in structural lipids which are known to be involved in embryo development.

Stress-induced osmotic adjustment in growing regions of barley leaves.

Young barley seedlings were stressed using nutrient solutions containing NaCl or polyethylene glycol and measurements were made of leaf growth, water potential, osmotic potential and turgor values of both growing (basal) and nongrowing (blade) tissues. Rapid growth responses similar to those noted for corn (Plant Physiology 48: 631-636) were obtained using either NaCl or polyethylene glycol treatments by which exposure of seedlings to solutions with water potential values of -3 to -11 bars effected an immediate cessation of leaf elongation with growth resumption after several minutes or hours. Latent periods were increased and growth resumption rates were decreased as water potential values of nutrient solutions were lowered. In unstressed transpiring seedlings, water potential and osmotic potential values of leaf basal tissues were usually -6 to -8 bars, and -12 to -14 bars, respectively. These tissues began to adjust osmotically when exposed to any of the osmotic solutions, and hourly reductions of 1 to 2 bars in both water potential and osmotic potential values usually occurred for the first 2 to 4 hours, but reduction rates thereafter were lower. When seedlings were exposed to solutions with water potential values lower than those of the leaf basal tissues, growth resumed about the time water potential values of those tissues fell to that of the nutrient solution. After 1 to 3 days of seedling exposure to solutions with different water potential values, cumulative leaf elongation was reduced as the water potential values of the root medium were lowered. Reductions in water potential and osmotic potential values of tissues in leaf basal regions paralleled growth reductions, but turgor value was largely unaffected by stress. In contrast, water potential, osmotic potential, and turgor values of leaf blades were usually changed slightly regardless of the degree and duration of stress, and blade water potential values were always higher than water potential values of the basally located cells. It is hypothesized that blades have high water potential values and are generally unresponsive to stress because water in most of the mesophyll cells in this area does not exchange readily with water present in the transpiration stream.