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Biomedical subjects

L Wolf

Publications and source records attributed to L Wolf.

At least 37 records · Page 2Linked to original sources
PubMed1997

Bioregeneration with maltose excreting Chlorella: system concept, technological development, and experiments.

ESA has been studying a small-scale bioregenerative system to support long-term biological experiments on-board spacecraft with oxygen, water and food. Core component of this system is a special photo-bioreactor in which a maltose-producing strain of the green micro alga Chlorella is cultivated. A number of auxiliary system components have been developed and are functioning on the ground according to the design specifications, among them a gas/liquid phase separator operating at the same time as a low shear-stress pneumatic pump, a dehumidifier, a maltose separator, and a liquid transfer system. All components have been designed so that--in principle--they will operate in weightlessness, though this has so far only been verified for the gas/liquid separator. The bioreactor and some of the auxiliary components have been integrated in a prototype system, which has been subjected to preliminary testing. The prototype has been sterilized successfully by autoclaving, except for the liquid transfer unit which is disinfected with isopropyl alcohol. Chlorella 241.80 has been cultured several times under controlled conditions for up to 8 weeks. Algal growth to a biomass concentration of 9 g.l-1 dry weight and maltose production to a concentration of 17 g.l-1 have been achieved. The low shear-stress pneumatic pump works reliably without the mechanical cell damage produced by other types of pumps. Contamination of the algal cultures by other micro-organisms has been avoided in most of the experiment runs. The maximum oxygen production rate observed was 2 ml.min-1, when the culture was aerated with air +0.5% CO2. This production rate is well below the CO2 gas transfer rate of 5 ml.min-1 under these conditions. It can probably be doubled by increasing the maximum light intensity of the illumination unit (currently 300 micro E.m-2S-1). In a preliminary closed gas loop experiment with Periplaneta as consumer, the possibility of controlling the Chlorella culture so as to match the needs of the consumer colony has been established. A maltose excreting Chlorella strain has been selected as the photosynthetic producer, because the technique for automatic culturing of this organism and harvesting its products was expected to be much less complex than that required for culturing higher plants. Although the prototype system developed in our laboratory has reached a high level of sophistication, there remain still a number of technical and biological problems to be solved before the feasibility of this concept is definitely demonstrated. The major problem is maintaining sterility, and eventually automatic cleaning and resterilization when contamination occurs during operation. The culture medium, which contains minerals, cell fragments and considerable amounts of sugars, is an ideal substrate for many other microorganisms. Another problem is long term operation. The prototype system contains many tubes and ducts which are perfused with culture medium. These may clog, which may lead to loss of sensor information essential for controlling the culture. Even when we succeed in demonstrating the feasibility of this concept, it will be a difficult task to demonstrate convincingly that the expected advantages of a bioregenerative system can outweigh the simplicity and reliability of a non-regenerative stored resource system in terms of volume, mass and amount of consumables required over the operational time.

Bioreactors↗
PubMed1997

[The use of thermography for the laryngeal diagnosis].

Authors presented possibility of clinical appliance of the M 4128 thermocamera in monitoring thermal changes of the skin and mucosa in upper respiratory tract diseases in patients treated at ENT Department Medical University of Lodz. Basing on the obtained results authors conclude usefulness of thermocamera in diagnosis of the head and neck tumors and inflammatory diseases and monitoring of the photodynamic therapy.

Adolescent↗
PubMed1996

Risk and protective factors affecting the adjustment of siblings of children with chronic disabilities.

OBJECTIVE: To examine the adjustment of nondisabled siblings of handicapped children. METHOD: In a 3-year longitudinal study, 46 siblings of children with pervasive developmental disorder (PDD), 45 siblings of children with Down syndrome, and 46 siblings of developmentally normal children (serving as controls) were examined at time 1 using the sibling, primary caretaker, and teacher as informants. Both direct and indirect variables related to sibling adjustment were considered. RESULTS: Significantly more difficulties were found in the siblings of children with PDD compared with the other two groups. Different correlates of adjustment were present in the siblings of the disabled compared with nondisabled children, and mediating factors differed in parent and teacher reports of internalizing difficulties in siblings of children with PDD. Marital satisfaction, lack of parental depression, a cohesive family, and a warm, nonconflictual sibling relationship were protective for normal control and Down syndrome siblings but not for PDD siblings. CONCLUSION: Findings underline the risks for the siblings of children with PDD and suggest the importance of a transactional mechanism rather than identification of single risk or protective factors in predicting sibling adjustment. Subsequent data analysis in this longitudinal study will assist in defining these mechanisms and allow for improved intervention strategies.

Adaptation, Psychological↗
PubMed1996

Bioregeneration in space.

ESA has been studying a small-scale bioregenerative system to support long-term biological experiments on-board spacecraft with oxygen, water, and food. Core component of this system is a special photo-bioreactor in which a maltose-producing strain of the green alga Chlorella is cultivated. In initial experiments this bioreactor has been tested, and the physiology of Chlorella has been studied. The optimal conditions for CO2 to O2 conversion and maltose production have been determined, and the possibility of controlling the culture so as to match the needs of the consumer has been established. A microgravity-compatible photo-bioreactor, and a maltose separator have been developed and are functioning on the ground according to the design specifications. Tests in weightlessness will have to be performed in the future. The components are to be integrated to a complete bioregenerative life support system, which will then be subjected to extensive testing. The EXEMSI project afforded an opportunity to study the mutual influence of a Chlorella culture and real biological oxygen consumers, the four crew members in the laboratory module of the isolation facility. Chlorella 241.80 was batch cultured in an airlift bioreactor by the crew for 25 days with air aspirated from the module. The crew members determined pH and cell density in samples withdrawn from the culture. Microscopic observations showed no evidence of contamination of the culture by other organisms. Growth rates were smaller than those observed in laboratory conditions. This is attributed to the relatively low average CO2 concentration in the module atmosphere: 0.1% against 0.5% in the air supply during the laboratory experiments. The data show no evidence of trace contaminant accumulation in the Chlorella culture. The results are encouraging and suggest the value of further simulated operational testing of the system.

Cell Count↗
PubMed1995

Oestrogen formation from androstenedione in human bone.

BACKGROUND AND OBJECTIVE: Peripheral aromatization of testosterone and androstenedione is the principal source for circulating oestrogens in men and in castrated and post-menopausal women. Since human bone is a target organ for androgens and oestrogens, aromatase activity was assessed in human spongiosa obtained from patients who were undergoing orthopaedic surgery. DESIGN AND PATIENTS: In initial experiments for assessing aromatization, oestrogen formation from 1,2,6,7-3H-androstenedione was compared with the release of tritiated water from 1 beta-3H-androstenedione. Since the rates of enzyme activity were similar with the two methods, rates of oestrogen formation were determined under standardized conditions with the tritiated water generation technique in bone specimens obtained from 4 men and 11 post-menopausal women. RESULTS: The apparent Km of the aromatase ranged between 6 and 50 nM (20.4 +/- 3.9; mean +/- SEM), values in the range of those reported for human placental microsomes. The maximum velocity (Vmax) of the aromatase activity ranged between 0.14 and 1.23 nmol/g DNA/h. CONCLUSIONS: Oestrogens formed in human bone may play a physiological role in steroid hormone action in this tissue.

Aged↗
PubMed1995

A tuberculosis control plan for ambulatory care centers.

Tuberculosis and a multidrug resistant form of TB have reemerged in epidemic proportions. Tuberculosis is more prevalent among HIV-infected individuals, the homeless, foreign-born individuals from countries with high rates of TB, prison inmates, individuals in long-term care facilities, individuals from low-socioeconomic backgrounds, and intravenous drug users. Urgent care centers, which have gained popularity as an easy access to medical care, are at risk for seeing undetected infectious patients. By developing a TB control plan for ambulatory care centers, specific triage criteria can be instituted to promote early identification of the potentially infectious patient and provide guidelines for identification, prevention, environmental controls, education, and follow-up of exposed health care workers. This article discusses the mandatory OSHA policy for occupational exposure to tuberculosis based on the 1993 CDC guidelines for TB transmission and how a TB control plan for ambulatory care centers can be developed from these guidelines.

Ambulatory Care Facilities↗
PubMed1995

[Digital method of assessing bone radiographs].

The computerized method of bone radiographs assessment has been presented. The radiographs were taken by standard technique with the aluminum wedge on the film and known exposition parameters as energy, time and the distance between the source and the subject. Specially designed software served to evaluate the intensity of film darkening. The method may be particularly useful for quantitative assessment of the callus in the healing phase of fractured bone. It may also be an alternative method (as cheaper one) to QCT or DPX in bone density evaluation in patients with metabolic bone diseases.

Absorptiometry, Photon↗
PubMed1994

"SYMBIOSE" SYstem for Microgravity BIOregenerative Support of Experiments.

SYMBIOSE is an ESA supported research and development program which aims at establishing a first pilot model of a closed ecological system, compatible with operation in weightlessness conditions, and dedicated to scientific investigations in the microgravity environment. It integrates microalgal photosynthesis within an artificial ecosystem featuring a symbiotic strain of Chlorella (241 .80, Gottingen), which synthesizes and excretes substantial amounts of maltose, and is further looped on a consumer compartment. A technological concept has been developed. It is presently being integrated in order to gain knowledge on the system dynamics, and ultimately demonstrate the feasibility of such a biotechnology. Preliminary work on the photosynthetic metabolism of this microalga is being undertaken in order 1) to support later a mathematical formalisation of the dynamics of this artificial ecosystem, and, on this basis, 2) to compensate for its lack of stability with model-based external control. The most recent results are presented, along with a new design of the photobioreactor which integrates efficient light energy capture, microgravity compatible gas transfer and reduced shear stress.

Bioreactors↗
PubMed1994

[Prosthesis replacement in the hip joint in prosthesis fracture. Clinical and radiological results after 5 years].

The results of 45 revisions performed for fracture of the femoral stem in patients with total hip replacements were reviewed after an average follow-up time of 5 (3-7) years. We were able to examine 38 of the patients. Surgery was performed in a standardized way through a posterior approach and with a dorsal proximal window in the femur. In 7 cases the femoral stem only was changed, while in 31 both components had to be replaced. The femoral components implanted were of the revision type, and were cemented and individually selected in each case. To stabilize large acetabular defects a combination of an acetabular support ring and a homologous bone graft was used in 21 cases; bank bone was used in a total of 28 hips. During surgery 1 fracture and 4 defects of the femur occurred. Good intraoperative stability of the femoral component was attained in every case, allowing full weight-bearing during mobilization unless acetabular instability was present. There were no deep infections. One dislocation had to be treated by closed reduction. Clinical evaluation was performed according to Merle d'Aubigné. Radiological loosening was classified according to Gruen, DeLee and Charnley. Clinical results were good in 33 (87%) and were rated as poor in 5. In the latter group a good correlation between subjective and objective parameters was noted in 4 of the 5 patients. Two acetabular and two femoral components in 3 patients were classified as radiologically loose; in 1 of these the cup was not changed at revision.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Parent and teacher ratings of attention-deficit hyperactivity disorder symptoms: implications for case identification.

This study was designed to evaluate the relationship between the DSM-III criteria for attention-deficit deficit disorder with hyperactivity (ADDH) and the DSM-III-R criteria for attention-deficit hyperactivity disorder (ADHD). Seventy-two children from an inner-city elementary school were evaluated using parent and teacher ratings on a scale consisting of the symptoms of DSM-III-R ADHD and oppositional-defiant disorder and DSM-III ADDH. Each child was also assessed using a psychometric test battery designed to examine cognitive function, attention, and activity level. Teacher ratings identified more children as DSM-III-R ADHD than DSM-III ADDH. Among these ADHD children, those who also met the ADDH criteria missed more targets on a continuous performance test (CPT) and were rated more overactive than controls. They also had a greater likelihood of being rated ADHD by parents. Children rated as meeting criteria for DSM-III-R ADHD, but not DSM-III ADDH, were not substantially different from controls on teacher ratings of overactivity, CPT performance, or parent ratings of ADHD, which raises questions regarding the nature and severity of the pathology in this group.

Attention↗
PubMed1993

Determination of residual 4'-aminomethyl-4,5',8-trimethylpsoralen and mutagenicity testing following psoralen plus UVA treatment of platelet suspensions.

Psoralens and UVA light have been used in the laboratory to study the inactivation of viruses that may be infrequently present in platelet concentrates that are prepared for transfusion. In order to evaluate safety aspects of the treatment of platelet suspensions with 4'-aminomethyl-4,5',8-trimethylpsoralen (AMT), we have investigated the residual levels and mutagenic potential of AMT after UVA phototreatment. 4'-aminomethyl-4,5',8-trimethylpsoralen, at a final concentration of 40 micrograms/mL, was added to platelet suspensions which contained 16% plasma and a synthetic medium. Platelet suspensions containing AMT were irradiated with up to 7.2 J/cm2 UVA light under normal oxygen levels. Residual levels of AMT were determined by HPLC and a bioassay based on bacteriophage phi 6 inactivation. The photodestruction of AMT or its activity by UVA was characterized by a D37 value of 0.6 and 0.3 J/cm2 with HPLC or bioassay, respectively. At 2.4 J/cm2 UVA, which results in approximately 5 log10 inactivation of vesicular stomatitis virus (VSV) and retention of platelet in vitro properties, 12% (HPLC) to 9% (bioassay) AMT remained. Like other psoralens, AMT was found to bind to serum proteins as shown by ultrafiltration. Results are consistent with approximately 36% of the initial drug load binding primarily to serum albumin. It was determined using 3H-AMT that 9 to 18% of radioactivity was bound to platelets in the absence of irradiation. Similar fractions (13 to 18%) of AMT were bound to platelets after 3.6 J/cm2 UVA irradiation, and 8 to 10% of total AMT was associated with saline-washed irradiated platelets and is presumably tightly bound.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteriophages↗
PubMed1992

Potassium-induced depolarization displaces exogenously incorporated gangliosides from cortical slices.

Freshly diced rat cerebral cortical tissue was incubated with [3H]gangliosides for 30 min, then perfused for 2 h with different physiological solutions. Significantly more labeled (exogenous) gangliosides were displaced when mildly depolarizing concentrations (25 mM) of KCl were included in the perfusion medium. This provides new evidence for an interaction between gangliosides and membrane mechanisms of excitation.

Animals↗
PubMed1992

[Fat pad signs and supinator fat line in cubital trauma].

The fat pad sign and the supinator fat line (SFL) are valuable diagnostic aids in the evaluation of bony cubital injuries. A total of 377 lateral X-rays of the elbow joint-including 121 fractures--were investigated. The supinator fat line exhibited bar-like and bird-like configurations in 55.9% and 41.8% of healthy test subjects, respectively. In the presence of a fracture, a wavy configuration, directed downwards from, or running parallel to, the upper edge of the radius, was seen in 95% of the cases. If in the event of an injury to the elbow a wavy configuration is seen in association with a positive anterior and/or posterior fat pad sign, bony involvement of the joint-forming elements may justifiably be suspected.

Adipose Tissue↗
PubMed1992

Androstenedione metabolism in cultured human osteoblast-like cells.

Bone is a target organ of androgens. The mechanism by which these steroids exert their action within bone cells is still poorly understood. The metabolism of androstenedione, the major circulating androgen in women, was, therefore, assessed in osteoblast-like bone cells cultured from bone of 16 postmenopausal women (mean age, 69 yr; range, 56-80) and 3 elderly men (mean age, 71 yr; range, 69-73) undergoing total hip replacement. Each cell strain was incubated under standardized conditions with varying concentrations of [1,2,6,7-3H]androstenedione (0.05-5 microM). In every instance 5 alpha-reduced metabolites and 17 beta-hydroxysteroids were formed. There was no correlation between the volumetric density of the resected bone and androstenedione metabolism of the corresponding cultured bone cell strains. The apparent Km for the 5 alpha-reductase activity (sum of androstanedione and dihydrotestosterone) of all 19 cell strains was 0.7 +/- 0.1 microM (mean +/- SEM), and the apparent Km for 17 beta-hydroxysteroid dehydrogenase (sum of testosterone and dihydrotestosterone) was 2.3 +/- 0.8 microM (mean +/- SEM), values similar to those reported for other androgen target organs. Our results demonstrate that human osteoblast-like cells have the capacity to transform androstenedione into the more potent biological androgens testosterone and dihydrotestosterone. Since the Km values of both 5 alpha-reductase and 17 beta-hydroxysteroid dehydrogenase exceed the serum androstenedione concentration, the formation of testosterone and dihydrotestosterone appears to be mainly a function of substrate availability.

Aged↗
PubMed1992

Psychometric differentiation of conduct disorder and attention deficit disorder with hyperactivity.

Using a retrospective chart review procedure, children diagnosed as having attention deficit disorder with hyperactivity (ADDH), conduct disorder (CD), and ADDH+CD, as defined by DSM-III, were compared on measures of cognitive and academic functioning as well as on a continuous performance test (CPT). The groups did not differ in age or IQ, but children in the ADDH and ADDH+CD groups missed significantly more target stimuli on the CPT and performed significantly poorer on measures of academic achievement than did the pure CD group. However, poor CPT performance was not accounted for by learning problems. These findings in clinically referred patient groups are consistent with dimensional and epidemiological studies that suggest that ADDH may be a cognitively based disorder, whereas CD children are characterized by behavioral symptoms with fewer cognitive and learning deficits.

Attention↗