Conservation of acquired morphology and community structure in aged biofilms after facing environmental stress.

The influence of growth history on biofilm morphology and microbial community structure is poorly studied despite its important role for biofilm development. Here, biofilms were exposed to a change in hydrodynamic conditions at different growth stages and we observed how biofilm age affected the change in morphology and bacterial community structure. Biofilms were developed in two bubble column reactors, one operated under constant shear stress and one under variable shear stress. Biofilms were transferred from one reactor to the other at different stages in their development by withdrawing and inserting the support medium from one reactor to the other. The developments of morphology and microbial community structure were followed by image analysis and molecular tools. When transferred early in biofilm development, biofilms adapted to the new hydrodynamic conditions and adopted features of the biofilm already developed in the receiving reactor. Biofilms transferred at a late state of biofilm development continued their initial trajectories of morphology and community development even in a new environment. These biofilms did not immediately adapt to their new environment and kept features acquired during their early growth phase, a property we called memory effect.

An automated method for the quantification of moving predators such as rotifers in biofilms by image analysis.

In natural environments as well as in industrial processes, microorganisms form biofilms. Eukaryotic microorganisms, like metazoans and protozoans, can shape the microbial communities because of their grazing activity. However, their influence on biofilm structure is often neglected because of the lack of appropriate methods to quantify their presence. In the present work, a method has been developed to quantify moving population of rotifers within a biofilm. We developed an automated approach to characterize the rotifer population density. Two time lapse images are recorded per biofilm location at an interval of 1s. By subtracting the two images from each other, rotifer displacements that occurred between the two images acquisition can be quantified. A comparison of the image analysis approach with manually counted rotifers showed a correlation of R(2)=0.90, validating the automated method. We verified our method with two biofilms of different superficial and community structures and measured rotifer densities of up to 1700 per cm(2). The method can be adapted for other types of moving organisms in biofilms like nematodes and ciliates.

Postural changes with aging in tetraplegia: effects on life satisfaction and pain.

OBJECTIVES: (1) To measure kyphosis and scoliosis in individuals with tetraplegia; (2) to examine the relation between kyphosis and scoliosis and years since injury; and (3) to determine the association between kyphosis and scoliosis and measures of pain, depression, and life satisfaction. DESIGN: Cross-sectional, case-control study. SETTING: University medical center and a free-standing university-affiliated rehabilitation hospital. PARTICIPANTS: (1) Ten individuals with tetraplegia I to 3 years postinjury (NT); (2) 10 individuals with tetraplegia 10 to 20 years postinjury (OT); and (3) 10 control individuals (C) matched to the other subjects on the basis of age, height, and weight. MAIN OUTCOME MEASURES: Radiographic measurements of kyphosis and scoliosis taken in a seated position, pain as measured by the short form of the McGill Pain Questionnaire (SF-MPQ), depression as measured by the Center for Epidemiological Studies-Depression Scale (CES-D), and life satisfaction as measured by the Life Satisfaction Index Assessment (LSIA) and the Craig Handicap Assessment and Reporting Technique (CHART). RESULTS: No significant differences were seen between the OT and NT groups with respect to age, height, or weight. In addition, no significant differences were found between the NT and OT groups with respect to measures of kyphosis and scoliosis. Individuals with tetraplegia had significantly higher (p < .05) measures of kyphosis (42 + 16.0 ) and scoliosis (14 degrees +/-9.2 degrees) than the C subjects (kyphosis, 32 degrees +/- 7.9 degrees ; scoliosis, 5 degrees+/-3.8 degrees). No correlation was found between scores on the SF-MPQ and degree of kyphosis or scoliosis. Significant differences were seen between the NT and OT groups on both CES-D (NT, 15.2+/-8.1; OT, 5.8+/-5.5) and LSIA (NT, 9.9+/-2.8; OT, 14.4+/-2.9). CONCLUSION: This study indicates that seated kyphosis and scoliosis develop early in individuals with tetraplegia and may not be progressive. No association was seen between pain and kyphosis or scoliosis in this relatively young sample (mean age of OT and NT combined, 34.8 years). Future research is needed to determine whether pain becomes a problem in individuals with significant kyphosis or scoliosis as they age.

Clinical evaluation of patients with hypertension and exercise-induced renal dysfunction.

An exercise-mediated renal omicron-iodohippurate transport abnormality was recently identified in patients with hypertension. The disturbance was not observed in normotensive controls. To learn more about this transient functional disturbance of the kidney, we obtained gamma camera hippurate renograms in 45 patients with hypertension. The final diagnoses indicated that 27 patients had essential hypertension, 15 had renal parenchymal or renovascular hypertension, 2 had malignant hypertension, and 1 had hypertension of pregnancy. We documented age, height, weight, global and unilateral renal function, blood pressure status, and antihypertensive medication used at time of scintigraphy. We also noted the serum catecholamine, sodium, and potassium levels. All patients were scintigraphed at rest and during exercise. The scintigraphic examination documented exercise-induced renal dysfunction in 28 (62%) patients (abnormal exercise renogram), while 17 (38%) had renograms not noticeably influenced by the exercise protocol (normal exercise renogram). When the results of scintigraphy were compared with the clinical data, a weak correlation was found between patient overweight and an abnormal response to exercise. There was no significant difference between groups with normal and abnormal exercise renograms with respect to the other parameters assessed. Exercise renography was not useful for differentiating renal and essential hypertension. Renography appears to demonstrate an exercise-mediated, transient, renal perfusion disturbance in certain patients with hypertension. The examination appears to assess a new parameter in hypertensive disease. Thus, the gamma camera renogram should be reevaluated in the patient with hypertension.