Biomedical subjects

J Raso

Publications and source records attributed to J Raso.

At least 37 records · Page 2Linked to original sources

PubMed2002

Environmental factors influencing the inactivation of Listeria monocytogenes by pulsed electric fields.

AIMS: To investigate the influence of the growth phase, growth temperature, storage time, pH and aw of the treatment medium on the resistance of Listeria monocytogenes to pulsed electric fields (PEF). METHODS AND RESULTS: Square wave pulses of 2 micros at a frequency of 1 Hz and 25 and 28 kV cm(-1) were used. Cells were more PEF resistant in the stationary than in the exponential phase at both incubation temperatures investigated (4 and 35 degrees C). Cells grown at 4 degrees C were more PEF sensitive than cells grown at 35 degrees C independent of the growth phase. After a treatment of 25 kV cm(-1) and 800 micros, 1.48, 3.86 and 5.09 log10 cycles of inactivation were obtained at pH 7.0, 5.4 and 3.8, respectively. A reduction in the aw of the treatment medium protected cells against PEF treatments. CONCLUSIONS: The PEF resistance of L. monocytogenes depended on different environmental factors. The influence of growth conditions and treatment medium characteristics should be known and controlled to obtain reproducible and reliable PEF inactivation data. SIGNIFICANCE AND IMPACT OF THE STUDY: Erroneous conclusions and misinterpretation of results are possible if factors affecting the PEF resistance of L. monocytogenes are not considered during PEF inactivation studies.

Colony Count, Microbial↗

PubMed2002

The development of scoliosis following pinealectomy in young chickens is not the result of an artifact of the surgical procedure.

Pinealectomy in young chickens consistently results in scoliosis which has many characteristics similar to those seen in adolescent idiopathic scoliosis. The mechanism underlying this phenomenon remains a mystery and it is not yet entirely clear whether some unidentified aspect of the extensive surgery is the major factor rather than the removal of the pineal gland. Four different types of pinealectomy surgery were performed on young chickens as well as deliberate damage to the cerebral cortex which simulated the extreme of any accidental damage that might occur during surgery. Scoliosis was assessed from weekly radiographs. No differences in incidence of scoliosis, degree of severity or pattern of curve development were observed for any of the experimental groups when compared with controls. In all groups approximately 55% of the chickens developed scoliosis that progressed rapidly. Different pinealectomy procedures and deliberate damage to the cerebral cortex produce scoliosis in young chickens with the same incidence and characteristics. This suggests strongly that the mechanism behind the phenomenon is due to the removal of the pineal gland and not some artifact of the extensive surgery. The pinealectomy model in young chickens is proving to be a good model for studying AIS in humans. An understanding of the mechanism underlying this phenomenon has the potential to provide further insights into the aetiology of AIS and can lead to the development of novel treatement methods.

Animals↗

PubMed2002

Brace monitoring system for the treatment of scoliosis.

Determining the efficacy of brace treatment for AIS has been hampered by poor data on the wear pattern of those children prescribed this treatment. Although there is some information on brace compliance, there is very little on how well the brace is secured and the resulting loads imposed on the trunk. The purpose of this study was to determine the daily brace wear pattern of adolescents prescribed Boston braces. The brace monitoring system consists of a force transducer and a microcomputer unit. A force transducer was placed in the lining of the Boston brace. The microcomputer unit was carried while the brace was worn. The force imposed by the brace pad during daily activity was recorded at 1 minute intervals over a period of 3 to 14 days. The samples were stored by the microcomputer. Five subjects (3F;2M; age: 14+/-2 years) who were to wear the brace full time were studied. The subjects adjusted their braces to a prescribed level of tightness as indicated by a light on the microcomputer. Overall compliance, compliance during school days, and forces imposed by the brace were analysed. The force provided by the Boston brace varies considerably during daily activity. Overall brace compliance was lower than expected, with 2 of 5 subjects wearing their brace infrequently. The compliance rate during school time was not different than during the rest of the study period. Peer pressure at school did not appear to affect brace compliance.

Adolescent↗

PubMed2002

Intelligent brace system for the treatment of scoliosis.

Measurement of the biomechanical effectiveness of a brace for the treatment of scoliosis has been hampered by the lack of compressive information about wear characteristics. Orthotists and orthopaedic surgeons believe that the effectiveness of bracing is correlated with the strap tensions. If the strap tensions can be maintained at the optimal level while patients wear their braces, a better treatment outcome may be obtained. However, strap tensions vary significantly during different activities. An intelligent brace system has been developed to control the strap tension so that the optimal prescribed level is maintained at all time. This system consists of an innovative strap tension transducer, a microcomputer unit and a motorized unit. The strap transducer has been developed with an accuracy +/- 1.0N in the range of 0 to 100N. An instrumented Boston brace was built to test the concept. When the strap tension was below 80% of the prescribed level for a 15 minutes interval, the microcomputer unit signaled the motor to tighten the strap. While the strap tension level was above 120% of the prescribed level for a 15 minutes interval, the motor reversed the direction. Laboratory testing results showed that the strap tension could be maintained at the optimal prescribed level.

Artificial Intelligence↗

PubMed2002

Spine-Straight device for the treatment of kyphosis.

Kyphosis is an excessive rounding of the upper spine. Its treatment depends upon the severity, the age of the patient and the levels of the spine that are affected. Early diagnosis is a key to providing optimal treatment. In a skeletally immature patient, an exercise program or bracing is the most commonly used treatment. However, the compliance of bracing for adolescents is poor and exercise training is labor intensive. The purpose of this study is to determine whether a Spine-Straight device can help patients to correct their kyphosis themselves and there by reduce back pain without the biomechanical support of a brace. The Spine-Straight device consists of an accelerometer and a microcomputer unit. The accelerometer is used to measure the kyphotic angle and the microcomputer unit controls a pager vibrator to alert patients when their posture exceeds personalized thresholds. The system was tested in the laboratory before used by subjects. The results were compared to back data obtained from a laser scanner imaging system. The maximum angle deviation between the laser scanner and the Spine-Straight device was 1.5 degrees. Two volunteers tested the systems for 2 days. The accelerometer was placed at the T3 location and the microcomputer unit was carried during daily activities. The angle measurement was recorded at 1 minute intervals during daily activity over a period of 2 days. The preliminary trials demonstrate subjects can improve their posture when feedback signals were provided.

Adult↗

PubMed2002

Assessing the impact of pelvic obliquity in post-operative neuromuscular scoliosis.

The goal of this pilot study was to explore the relationship between pelvic obliquity and patient pain, sitting tolerance, pressure sores, and function. Five neuromuscular patients who underwent spinal surgery 6-26 weeks prior to assessment took part in this on-going study (4F; 1M); age at surgery (14.6 +/- 2.6 years). Pelvic obliquity was measured from pre- and post-operative anterior-posterior radiographs. A force-sensing pad with a grid of sensors was placed on a flat surface and the weight distribution pattern was recorded. The pressures were divided into left and right sides and peak levels were noted on each side. The parents or caregivers completed a questionnaire on their child's pain, sitting tolerance, pressure sores, and functional abilities. Pelvic obliquity was reduced after surgery by approximately 50% depending on the method used to assess pelvic obliquity. The major curve was reduced from 64 degrees(10 degrees) to 39 degrees (10 degrees). Post operatively, the average pressure (left/right side) ranged from 1.2 to 2.0 (average 1.6). The peak pressure ratio ranged from 1.1 to 1.9 (average 1.4). The ratio of left/right pressure correlated with improvement in pelvic obliquity (r2=0.9). Pain was moderate/severe in the 2 patients with the least correction as measured with the Cobb angle from surgery; both improved following surgery. Two patients suffered pressure sores pre-operatively and one post-operatively. Only 3/5 felt sitting endurance had increased. All parents felt their child sat straighter after surgery. The outcome measures of pain, pressure sores, sitting tolerance, and function were not well related to the amount of pelvic obliquity. More candidates and a longer follow-up may shed light on the many relationships.

Activities of Daily Living↗

PubMed2001

Development of scoliosis following pinealectomy in young chickens is not the result of an artifact of the surgical procedure.

Pinealectomy in young chickens consistently results in scoliosis, which has many characteristics similar to those seen in adolescent idiopathic scoliosis. The mechanism underlying this phenomenon remains a mystery and it is not yet entirely clear whether some unidentified aspect of the extensive surgery is the major factor rather than the removal of the pineal gland. Four different types of pinealectomy surgery were performed on young chickens as well as deliberate damage to the cerebral cortex which simulated the extreme of any accidental damage that might occur during surgery. Scoliosis was assessed from weekly radiographs. No differences in incidence of scoliosis, degree of severity, or pattern of curve development were observed for any of the experimental groups when compared with controls. In all groups approximately 55% of the chickens developed scoliosis that progressed rapidly. Different pinealectomy procedures and deliberate damage to the cerebral cortex produce scoliosis in young chickens with the same incidence and characteristics. This suggests strongly that the mechanism behind the phenomenon is due to the removal of the pineal gland and not some artifact of the extensive surgery. The pinealectomy model in young chickens is proving to be a good model for studying AIS in humans. An understanding of the mechanism underlying this phenomenon has the potential to provide further insights into the etiology of AIS and can lead to the development of novel treatment methods.

Animals↗

PubMed2000

Influence of different factors on the inactivation of Salmonella senftenberg by pulsed electric fields.

The influence of growth phase, cell concentration, pH and conductivity of treatment medium on the inactivation of Salmonella senftenberg by high electric field pulses (HELP) was studied. Cells were more resistant to HELP treatments at the beginning of the logarithmic phase and at the stationary phase. Microbial inactivation was not a function of the initial cell concentration. At constant input voltage, electric field strength obtained in the treatment chamber depended on medium conductivity. At the same electric field strength, conductivity did not influence S. senftenberg inactivation. At the same conductivity, inactivation of S. senftenberg was bigger at neutral than acidic pH.

Electricity↗

PubMed2000

Paradoxical embolism-report of a case involving four organ systems.

Paradoxical embolism through a patent foramen ovale (PFO) can involve multiple organs simultaneously. The most commonly involved sites are the cerebrum and the extremities. Paradoxical embolism to coronary arteries or upper extremities is relatively uncommon. We report a case of acute pulmonary embolism and paradoxical embolism through a patent foramen ovale involving the left upper extremity, brain, and coronary artery. Early diagnosis in the emergency department was made by a trans-esophageal echocardiogram, and the patient was successfully treated with intravenous t-PA and heparin. Patients with acute pulmonary embolism or deep venous thrombosis who also develop signs of systemic embolism should be evaluated for a patent foramen ovale.

Axillary Artery↗

PubMed2000

Heat resistance of Alicyclobacillus acidocaldarius in water, various buffers, and orange juice.

The effect of the pH or the composition of the heating medium and of the sporulation temperature on the heat resistance of spores of a thermoacidophilic spore-forming microorganism isolated from a dairy beverage containing orange fruit concentrate was investigated. The species was identified as Alicyclobacillus acidocaldarius. The spores showed the same heat resistance in citrate-phosphate buffers of pH 4 and 7, in distilled water, and in orange juice at any of the temperatures tested (D120 degrees C = 0.1 min and z = 7 degrees C). A raise in 20 degrees C in the sporulation temperature (from 45 to 65 degrees C) increased the heat resistance eightfold (from D110 degrees C = 0.48 min when sporulated at 45 degrees C to 3.9 min when sporulated at 65 degrees C). The z-values remained constant for all sporulation temperatures. The spores of this strain of A. acidocaldarius were very heat resistant and could easily survive any heat treatment currently applied to pasteurize fruit juices.

Bacillaceae↗

PubMed2000

Inactivation of Salmonella Enteritidis, Salmonella Typhimurium, and Salmonella Senftenberg by ultrasonic waves under pressure.

The resistance of Salmonella Enteritidis (ATCC 13076), Salmonella Typhimurium (ATCC 13311), and Salmonella Senftenberg 775W (ATCC 43845) to ultrasonic waves under pressure treatments, at sublethal (manosonication) and lethal temperatures (manothermosonication) in citrate-phosphate buffer and in liquid whole egg was investigated. The influence of treatment parameters on the inactivation rate of manosonication was also studied. Decimal reduction times (Dt) of Salmonella Enteritidis, Salmonella Typhimurium, and Salmonella Senftenberg 775W corresponding to a heat treatment at 60 degrees C in pH 7 buffer and in liquid whole egg were 0.068, 0.12, and 1.0 min for buffer, and 0.12, 0.20, and 5.5 min for liquid whole egg. Those corresponding to a manosonication treatment (117 microns, 200 kPa, 40 degrees C) in both media were 0.73, 0.78, and 0.84 min, and 0.76, 0.84, and 1.4 min, respectively. When the amplitude of ultrasonic waves was increased linearly, the inactivation rate of manosonication increased exponentially. The inactivation rate also increased when pressure was raised. However, the magnitude of this increase was progressively smaller at higher pressures. The magnitude of the influence of the amplitude of ultrasonic waves and static pressure on the inactivation rate of manosonication was the same in the three serotypes investigated. Whereas a heat treatment at 60 degrees C only attained a 1/2-log cycle reduction in the number of Salmonella Senftenberg 775W survivors, a manothermosonication treatment (117 microns and 200 kPa) at this temperature attained a 3-log cycle reduction.

Animals↗

PubMed1999

Heat resistance of Yersinia enterocolitica grown at different temperatures and heated in different media.

In the range of 4-20 degrees C, growth temperature did not influence the heat resistance at 54-66 degrees C for Yersinia enterocolitica at pH 7 in citrate phosphate buffer. However, when cells were grown at 37 degrees C. the D62 increased from 0.044 to 0.17 min. This increase was constant at all heating temperatures tested (z = 5.7-5.8). Growth temperature did not influence the proportion of heat-damaged cells after a heat treatment, as measured by their response to a 2% of sodium chloride added to the recovery medium. The sensitivity of heat treated cells to nisin or lysozyme depended on growth temperature: Whereas the number of cells grown at 4 degrees C surviving heat treatment was the same regardless of the presence of 100 IU/ml of nisin or 100 microg/ml of lysozyme in the recovery medium, that of cells grown at 37 degrees C was, in these media, lower. The pH of maximum heat resistance in citrate phosphate buffer was pH 7 for cells grown at 37 degrees C, but pH 5 for those grown at 4 degrees C. In both suspensions the magnitude of the effect of pH on heat resistance was constant at all heating temperatures. For cells grown at 4 degrees C the heat resistance at 54-66 degrees C, in skimmed milk or pH 7 buffer, was the same. For cells grown at 37 degrees C this also applied for heat treatment at 66 degrees C but at 56 degrees C the heat resistance in skimmed milk was higher.

Animals↗

PubMed1999

Influence of pH on heat resistance of spores of Bacillus coagulans in buffer and homogenized foods.

The influence of pH of heating menstruum (McIlvaine buffer) on the heat resistance of Bacillus coagulans spores has been investigated and compared with the heat resistance in homogenized tomato and asparagus at pH 7 and 4 at a wide range of temperatures. Spores were less heat resistant in all menstrua at acid pH. The magnitude of this effect was greatest at the lowest heating temperatures tested. z values in buffer increased from 8.9 degrees C at pH 7 to 10.5 degrees C at pH 4. pH of menstrua was the main influencing factor, but media composition also influenced heat resistance: at pH 7 heat resistance was similar in all menstrua (D111 degrees C = 1.6 min) but at pH 4 the heat resistance in homogenized foods (D111 degrees C = 0.26 min in tomato and D111 degrees C = 0.28 min in asparagus) was lower than in buffer (D111 degrees C = 0.49 min). The reduced influence of the acidification of media on the heat resistance of B. coagulans at higher temperatures should be taken into account when a rise in the temperature of treatment for canned vegetables is considered to shorten duration of heat processes.

Bacillus↗

PubMed1999

The production of scoliosis after pinealectomy in young chickens, rats, and hamsters.

STUDY DESIGN: This study involved weekly radiographic examination of pinealectomized rats, hamsters, and chickens to observe the development of scoliosis. OBJECTIVES: To determine whether pinealectomy produces scoliosis in animals more closely related phylogenetically to humans than to chickens, namely rats and hamsters, which are representative of mammals. SUMMARY OF BACKGROUND DATA: Pinealectomy in 3-day-old chickens has consistently resulted in the development of scoliosis with many characteristics similar to those seen in patients with adolescent idiopathic scoliosis. It has not been determined whether this phenomenon is restricted solely to chickens or is applicable to other animals, especially those more closely related to humans. METHODS: The pineal gland was removed from young rats, hamsters, and chickens. All animals underwent radiography weekly to detect the development of any scoliosis. Weight and length measurements were also taken weekly, and serum melatonin levels were determined at the time the animals were killed. RESULTS: Scoliosis was not observed in either the rats or the hamsters. In contrast, scoliosis developed in 10 of 21 chickens. Serum melatonin levels in all pinealectomized animals were zero. CONCLUSIONS: In contrast to the chickens, pinealectomy does not seem to cause scoliosis in either young rats or hamsters. The reasons for this discrepancy may include differences in the physiology and spinal morphology of the rat and hamster in comparison with the chicken. In the pinealectomized chickens, the results also suggest that future scoliosis development might be indicated by a significant increase in size when they are compared with pinealectomized chickens that do not develop scoliosis. Such differences in growth rates also distinguish patients with adolescent idiopathic scoliosis.

Animals↗

PubMed1999

Influence of different factors on the output power transferred into medium by ultrasound.

The influence of several factors (amplitude of ultrasonic waves, external static pressure, temperature and viscosity of medium) acting, either individually or in combination, on the amount of power transferred to a liquid medium during ultrasonication (power output) was measured by calorimetry. At constant amplitude (150 microns) and pressure (200 kPa), the power output decreased as the temperature was raised. The effect of temperature could be compensated by increasing pressure. The magnitude of the increase in power output due to raising the pressure depended on the pressure range and the treatment temperature. At all temperatures and pressures studied, the power output increased exponentially when the amplitude was increased linearly. The magnitude of this power output did not depend on the temperature or pressure of treatment. At 40 degrees C the magnitude of the increase in power output due to increasing the pressure was not influenced by the amplitude of sonic waves. The power output increased as the viscosity of the medium was increased. The magnitude of this effect did not depend on the amplitude but on the static pressure.

Journal Article↗

PubMed1999

Bacterial resistance to ultrasonic waves under pressure at nonlethal (manosonication) and lethal (manothermosonication) temperatures.

The decimal reduction times of Streptococcus faecium, Listeria monocytogenes, Salmonella enteritidis, and Aeromonas hydrophila corresponding to heat treatment at 62 degrees C were 7.1, 0.34, 0.024, and 0.0096 min, and those corresponding to manosonication treatment (40 degrees C, 200 kPa, 117 microm) were 4.0, 1.5, 0.86, and 0.90 min, respectively. The manosonication decimal reduction times of the four species investigated decreased sixfold when the amplitude was increased from 62 to 150 microm and fivefold when the relative pressure was raised from 0 to 400 kPa. In L. monocytogenes, S. enteritidis, and A. hydrophila, the lethal effect of manothermosonication was the result of the addition of the lethal effects of heat and manosonication, whereas in S. faecium it was a synergistic effect.

Aeromonas hydrophila↗

PubMed1998

Influence of several environmental factors on the initiation of germination and inactivation of Bacillus cereus by high hydrostatic pressure.

The influence of pH, aw, L-alanine, and fat concentration of milk on the initiation of germination and inactivation by high hydrostatic pressure (HHP) (250 mPa at 25 degrees C for 15 min and 690 mPa at 40 degrees C for 2 min) of Bacillus cereus sporulated at 20, 30 and 37 degrees C was investigated. B. cereus sporulated at the lowest temperature was found to be the most resistant to the initiation of germination and inactivation by HHP. At ambient pressure, the rate and extension of germination induced by L-alanine were also lower in B. cereus sporulated at 20 than 30 or 37 degrees C. The optimum pH for the germination and inactivation of B. cereus depended on the sporulation temperature. At 250 mPa the extent of germination for the three suspensions increased with higher pH. At 690 mPa, the pH barely affected the germination of B. cereus sporulated at 20 degrees C (3 log cycles), but the inactivation increased as the pH of the medium was lowered. After the same treatment, pressure optimally initiated the germination of B. cereus sporulated at 30 and 37 degrees C (6-7 log cycles) around neutral pH. Higher inactivation was obtained at pH 6. High concentrations of sucrose protected the spores from the germinating and inactivating effect of HHP. At aw 0.92, no germination was detected when the spores were pressurized at 250 mPa, and only 1 log cycle of B. cereus sporulated at 20 and 30 degrees C and 2 log cycles of B. cereus sporulated at 37 degrees C were germinated at 690 mPa. In addition, no inactivation was observed at aW 0.92 even at 690 mPa. The presence of L-alanine in the medium of pressurization increased the germination initiated by HHP at 250 mPa, but not at 690 mPa. A combination of 250 mPa at 25 degrees C with L-alanine (100 mM) was found to give an additive response. The initiation of germination and inactivation by HHP were not affected by the fat concentration of the milk.

Alanine↗

PubMed1998

Sporulation temperature affects initiation of germination and inactivation by high hydrostatic pressure of Bacillus cereus.

The influence of sporulation temperature (20, 30 and 37 degrees C) on the heat resistance and initiation of germination and inactivation by high pressure on Bacillus cereus ATCC 14579 spores was investigated. Spores sporulated at 37 degrees C were the most heat-resistant. However, spores sporulated at 20 degrees C were more resistant to the initiation of germination and inactivation by high pressure. Spores were more sensitive to pressure at higher treatment temperatures. At 25 degrees C, there was an optimum pressure (250 MPa) for the initiation of germination for the three suspensions; at higher temperatures an increase of pressure up to 690 MPa caused progressively more germination. Resistance to the germinability and inactivation by high pressure of the spore population was distributed heterogeneously. Semilogarithmic curves of the ungerminated and survival fraction of B. cereus spores were concave. The resistant fraction of the spore population was lower at higher treatment temperatures. At 60 degrees C after 30 s of treatment at 690 MPa almost 5 log cycles of the population of B. cereus sporulated at 20 degrees C was germinated, and more than 7 log cycles of the population of B. cereus sporulated at 30 and 37 degrees C. The same treatment inactivated 4, 6 and 7 log cycles of the population of B. cereus sporulated at 20, 30 and 37 degrees C, respectively.

Air Pressure↗