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Biomedical subjects

E Rosenfeld

Publications and source records attributed to E Rosenfeld.

At least 19 recordsLinked to original sources
PubMed2003

[Non-thermal non-cavitational effects of ultrasound].

The non-thermal, non-cavitational (NTNC-) effects of medical ultrasound are based essentially on the direct and indirect effects of the sound radiation pressure. This article introduces the biophysics of the basic mechanisms and describes possible clinical implications using selected examples. It has been determined that generally no additional risks ensue through the effects of NTNC used purely for diagnostic purposes. Significant effects can only be detected under the conditions which prevail during therapeutic exposure. The question as to whether the pulse Doppler technique is completely harmless cannot be answered conclusively at this time. The synergetic effects between ultrasound and contrast media have not yet been examined thoroughly.

Biophysics↗
PubMed2002

The human tuftelin gene and the expression of tuftelin in mineralizing and nonmineralizing tissues.

Tuftelin has been suggested to play an important role during the development and mineralization of enamel, but its precise function is still unclear. This article reviews major milestones in the discovery, structural characterization, expression, localization, and conservation of tuftelin in different vertebrate species. It focuses on the structure of the human tuftelin gene, which has recently been deciphered [12]. It describes the exon-intron organization, sizes and structure, the promoter structure, and the newly discovered alternatively spliced human tooth-bud tuftelin mRNA transcripts. It also examines information on the structural motifs in the human-derived tuftelin protein and how they relate to tuftelin from other species. It reviews our recent results on the transcription of tuftelin mRNA and protein expression in several nonmineralizing soft tissues, using reverse-transcription polymerase chain reaction (RT-PCR) followed by DNA cloning and sequencing, indirect immunohistochemistry, immunohistochemistry combined with confocal microscopy, and in situ hybridization. These results and earlier Northern blot results show that tuftelin, in addition to being expressed in the developing and mineralizing tooth, is also expressed in several nonmineralizing soft tissues, suggesting that tuftelin has a universal function and/or a multifunctional role.

Alternative Splicing↗
PubMed1998

Prospects for smoking cessation among people with insulin-dependent diabetes.

As part of an initiative to develop a smoking cessation resource tailored to the needs of smokers with diabetes, we undertook a survey of 223 people with insulin-dependent diabetes (IDDM) aged 15-40 years, 54 of whom were smokers. Smokers had high levels of awareness that smoking increases the risk of heart and peripheral vascular disease, but were less aware of the risk of microvascular complications. Nearly half of the smokers had other members of the household who were smokers, and 56% indicated they would expect to receive no more than a little encouragement from friends and family members to quit. Concern about weight gain and dietary adherence was a barrier to quitting smoking for approximately one-third of smokers. Seventy percent of smokers recalled advice to quit smoking from a general practitioner, but this most often had involved minimal advice to quit. There is scope for patient education with respect to microvascular complications exacerbated by smoking, and a need to consider the smoking habits of other household members and enlist their active support for smoking cessation.

Adolescent↗
PubMed1998

Diabetes complications and risk factors in an Australian population. How well are they managed?

BACKGROUND: This study aimed to explore the relationship between complications and risk factors in the type 2 diabetes population, and to assess the level of assistance people with diabetes receive in controlling their risk factors. METHODS: Participants were recruited from representative population surveys of South Australians aged over 18 years. Participants were asked a series of questions about their risk factors and the advice and assistance they received from their general practitioner (GP) in modifying their risk factors. Additionally, participants were clinically tested for a number of macro and microvascular complications. RESULTS: South Australians with type 2 diabetes have a high prevalence of risk factors, with the majority being overweight or obese, doing no vigorous exercise and having high blood pressure. They also have a high prevalence of complications, with 53% having at least one macrovascular complication and 66% having at least one microvascular complication. Additionally, participants reported high levels of GP advice and assistance on the risk factors where pharmacological controls were available, but low levels of assistance where non-pharmacological interventions were needed to control the risk factor. CONCLUSIONS: The prevalence of diabetes risk factors and complications among South Australians with type 2 diabetes is a cause for concern, as is the lack of assistance offered by GPs to modify risk factors. Multi-disciplinary approaches to the control of risk factors and patient self-management and education are critical to the progression and success of diabetes care.

Adult↗
PubMed1996

Visualization of the reaction layer in the immediate membrane vicinity.

Coupled processes of diffusion and chemical reaction are quantitatively analyzed by means of proton concentration profile measurements in the immediate membrane vicinity. Because mass transfer across the unstirred layer (USL) is thought to proceed via diffusion, only the size of the USL is used as a scale for diffusion restrictions. Limitations associated with the finiteness of the reaction rate are characterized by the size of the reaction layer (RL). The latter is defined as the distance from the membrane where equilibrium is reached if transmembrane diffusion is followed by chemical reactions proceeding in the solution layers adjacent to the membrane. The well-known reaction of acetaldehyde oxidation catalyzed by alcohol dehydrogenase in the presence of NADH was selected because it is accompanied by an easily measurable alkalinization of the solution. The enzyme/coenzyme and the substrate were added to opposite sides of the membrane. A theoretical model describing the reaction and diffusion kinetics enabled us to calculate the size of the RL from the pH profile within the USL of a planar bilayer membrane showing a high proton permeability. As the enzyme concentration increased, the initially reaction-limited kinetics of the total turnover became diffusion limited under our experimental conditions due to a dramatic shortening of the RL.

Acetaldehyde↗
PubMed1996

Large outbreak of pertussis among young children in Chicago, 1993: investigation of potential contributing factors and estimation of vaccine effectiveness.

BACKGROUND: An outbreak of pertussis from July, 1993, to April, 1994, in Chicago was investigated to identify potential contributing factors. METHODS: Surveillance was enhanced to identify cases. Information from a vaccination coverage survey was used to define a retrospective cohort to estimate vaccine effectiveness of three or more doses of pertussis vaccine. RESULTS: The median age of 218 reported cases was 8 months, 46% had Hispanic surnames and cases were clustered geographically. Vaccination status was known for 173 of 191 (91%) children younger than 6 years of age. Of these 173, 90 (52%) were younger than 7 months, and 35 (20%) children at least 7 months of age had received fewer than 3 doses of pertussis vaccine. Pertussis vaccine effectiveness was 76% (95% confidence interval, 29 to 92). CONCLUSIONS: The limited ability of the current pertussis vaccination schedule to protect young infants accounted for 52% of cases, primary vaccine failure accounted for 28% of cases and failure to vaccinate children on time accounted for 20% of cases in young children. Low vaccine effectiveness did not appear to be a contributing factor.

Causality↗
PubMed1993

Effect of ultrasound on the pH profiles in the unstirred layers near planar bilayer lipid membranes measured by microelectrodes.

A pH shift in the unstirred layers (USLs) near a planar lipid bilayer membrane was induced by the diffusion of acetic acid along a concentration gradient. By means of a microelectrode technique it was shown that ultrasound decreases the thickness of the USL and that this reduction was much more pronounced on the side facing the ultrasound transducer than on the opposite side of the membrane. The effect depending on sound frequency and pressure is caused by the unidirectional fluid flow built up between transducer surface and membrane, the so-called quartz wind. Theoretical considerations based on the equations of the acoustic streaming near interfaces combined with the diffusion equation allow to predict the thickness of the USL if the sound field parameters are known.

Acetates↗
PubMed1993

Effects of ultrasound on the steady-state transmembrane pH gradient and the permeability of acetic acid through bilayer lipid membranes.

The irradiation of bilayer lipid membranes with continuous ultrasound of a frequency of 8.2 MHz and a spacial peak time average (SPTA) intensity of 0.4 W/cm2 reduces the thickness of the unstirred layer up to 40% of its initial value under our conditions. This result was obtained from measurements of the transmembrane potential which appears after the addition of a protonophore in the presence of a gradient of acetic acid. Ultrasound exposure decreases this potential when the pH of the buffer solutions is much higher than the pK of CH3COOH and has no effect at low pH values. The latter can be explained by a simultaneous increase of the permeability of acetic acid and the buffer substances, respectively, due to ultrasound irradiation.

Acetates↗
PubMed1992

[Meningeal myelomatosis. Presentation of a case].

The case of a 36-year old man with IgA kappa multiple myeloma in whom meningeal myelomatosis developed is reported, and a brief review of previously published cases is made. Meningeal involvement develops in patients with high tumoral mass myeloma. Because of its poor prognosis, central nervous system chemoprophylaxis based on clinical and cerebrospinal fluid data, and systemic treatment according to severity, is suggested.

Adult↗
PubMed1990

Positive and negative effects of diagnostic intensities of ultrasound on erythrocyte blood group markers.

Human erythrocytes were exposed in vitro to diagnostic intensities of ultrasound. Various antigenic tests were conducted to see if the different blood group markers had been changed. No change was observed following sonication for Ss, M, K1, ABO, and the rhesus factors. However a marked reduction was found for the N antigen when assayed using the lectin isolated from Vicia graminea. Several experiments were performed to ensure that this effect was not an artefact. If the cells were not resuspended in fresh medium immediately following sonicating then the magnitude of the effect rapidly decreased. We were unable to detect free N antigen in the supernatants from the sonicated cell suspensions. We were also unable to demonstrate changes in the level of the N antigen following sonication if we used anti-N sera from rabbits. A surprising observation was that different batches of the lectin preparation from the same manufacturer could eliminate the effect.

ABO Blood-Group System↗
PubMed1990

The photodynamic effect of rose bengal on proteins of the mitochondrial inner membrane.

Photodynamic action promoted by Rose Bengal was evaluated in solutions of unsaturated fatty acids or histidine, and on beef heart submitochondrial particles. Rose Bengal-promoted photooxidation of histidine was mainly due to the opening up of the imidazole ring by singlet oxygen. Photosensitization of polyunsaturated fatty acids (PUFA) resulted in oxygen consumption and thiobarbituric acid-reactive substances (TBARS) formation, the extent of which was linearly related to the increasing degree of unsaturation. Photosensitization of submitochondrial particles caused oxygen consumption and TBARS production. These processes involved two different reaction components: during the first, most of the mitochondrial proteins were inactivated, the most sensitive being succinate dehydrogenase and cytochrome c. The values for the rate ratios of [TBARS] formation/[O2] consumption for the first and second phase were 0.36 and 1.32%, respectively, pointing to a larger contribution of lipid peroxidation during the second phase. The calculation of the rate constants for reaction of singlet oxygen with mitochondrial proteins suggests that singlet oxygen is more reactive towards proteins than to PUFA. The biological role of this selectivity is discussed in terms of the mitochondria as one of the first targets for photosensitized reactions.

Animals↗
PubMed1989

Photosensitization of single-strand breaks in pBR322 DNA by rose bengal.

Rose bengal photosensitized the formation of frank single-strand breaks (SSBs) in double-stranded, supercoiled pBR322 DNA as measured by neutral agarose electrophoresis. The yield of SSBs followed first order kinetics with respect to light fluence and dye concentration. The efficiency of cleavage was more than 20 times greater in an argon atmosphere than in an oxygen atmosphere. The quantum yield in an air atmosphere was 1.7 (+/- 0.3) X 10(-8). Sodium azide quenched the cleavage more efficiently in an oxygen atmosphere than when the oxygen concentration was reduced. Isopropanol and mannitol were poor quenchers; ribose-5-phosphate and guanosine-5'-monophosphate did not quench the cleavage. Substituting D2O for H2O increased the yield of SSBs in both oxygen and oxygen-depleted atmospheres. The results are consistent with initiation of cleavage by reaction of the triplet state of rose bengal (or a radical derived from it) with DNA. In the presence of oxygen, an additional mechanism is introduced.

DNA Damage↗
PubMed1988

[The incisor of the rat--not only an indicator for disorders of homeostasis].

In experimental endocrinology and for studies of disturbed homeostasis caused by alterations of mineral metabolism rat incisors are known test model. Recently they will be relevant to interpret effects of xenobiotics. In our experiments we found remarkable correlations between specific organ toxicity (affinity) and histotropic effects in the incisors (enamel or dentine), further variations of the reaction in relation to the time of application.

Animals↗
PubMed1988

[Effect of metabolic changes in the liver on the cytotoxic activity of cyclophosphamide in the incisor of rats].

The incisor of the rat is a sensitive biological indicator which records nutritive and hormonal disorders as well as toxic influences. The present investigation was aimed to provide information whether or not the manifestation of cyclophosphamide-caused hypoplasias could be altered by an induction (phenobarbital) or inhibition (carbon tetrachloride) of the liver biotransformation capacity. Cyclophosphamide (15 or 30 mg/kg) was injected intraperitoneally. Pretreatment of the rat with phenobarbital produced an increase (35%) of the malformation, whereas carbon tetrachloride led to a dose dependent decrease (30 or 50%). Our investigations suggest that the cyclophosphamide induced defect of the incisor is due to an alteration of the metabolic liver function.

Animals↗
PubMed1987

Effects of ultrasound on the catalytic activity of matrix-bound glucoamylase.

The effect of ultrasonic waves on the activity of glucoamylase bound to a porous polystyrene matrix is investigated in this Paper. The immobilized enzyme was sonated in a flow cuvette at frequencies between 1 and 11 MHz and sound intensities up to 5 kW m-2. The effect was measured as a function of the type and concentration of the substrate, carrier particle size, flow rate of the substrate solution and ultrasonic frequency. The activity increase is discussed in terms of a possible ultrasonic mechanism.

Catalysis↗