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Biomedical subjects

J Levy

Publications and source records attributed to J Levy.

At least 19 recordsLinked to original sources
PubMed2006

Transport of Escherichia coli bacteria through laboratory columns of glacial-outwash sediments: estimating model parameter values based on sediment characteristics.

Bacterial transport through cores of intact, glacial-outwash aquifer sediment was investigated with the overall goal of better understanding bacterial transport and developing a predictive capability based on the sediment characteristics. Variability was great among the cores. Normalized maximum bacterial-effluent concentrations ranged from 5.4x10(-7) to 0.36 and effluent recovery ranged from 2.9x10(-4) to 59%. Bacterial breakthrough was generally rapid with a sharp peak occurring nearly twice as early as the bromide peak. Bacterial breakthrough exhibited a long tail of relatively constant concentration averaging three orders of magnitude less than the peak concentration for up to 32 pore volumes. The tails were consistent with non-equilibrium detachment, corroborated by the results of flow interruption experiments. Bacterial breakthrough was accurately simulated with a transport model incorporating advection, dispersion and first-order non-equilibrium attachment/detachment. Relationships among bacterial transport and sediment characteristics were explored with multiple regression analyses. These analyses indicated that for these cores and experimental conditions, easily-measurable sediment characteristics--median grain size, degree of sorting, organic-matter content and hydraulic conductivity--accounted for 66%, 61% and 89% of the core-to-core variability in the bacterial effective porosity, dispersivity and attachment-rate coefficient, respectively. In addition, the bacterial effective porosity, median grain size and organic-matter content accounted for 76% of the inter-core variability in the detachment-rate coefficient. The resulting regression equations allow prediction of bacterial transport based on sediment characteristics and are a possible alternative to using colloid-filtration theory. Colloid-filtration theory, used without the benefit of running bacterial transport experiments, did not as accurately replicate the observed variability in the attachment-rate coefficient.

Bromides↗
PubMed2006

Modulation of the infant immune responses by the first pertussis vaccine administrations.

Many efforts are currently made to prepare combined vaccines against most infectious pathogens, that may be administered early in life to protect infants against infectious diseases as early as possible. However, little is known about the general immune modulation induced by early vaccination. Here, we have analyzed the cytokine secretion profiles of two groups of 6-month-old infants having received as primary immunization either a whole-cell (Pw) or an acellular (Pa) pertussis vaccine in a tetravalent formulation of pertussis-tetanus-diphtheria-poliomyelitis vaccines. Both groups of infants secreted IFN-gamma in response to the Bordetella pertussis antigens filamentous haemagglutinin and pertussis toxin, and this response was correlated with antigen-specific IL-12p70 secretion, indicating that both pertussis vaccines induced Th1 cytokines. However, Pa recipients also developed a strong Th2-type cytokine response to the B. pertussis antigens, as noted previously. In addition, they induced Th2-type cytokines to the co-administrated antigen tetanus toxoïd, as well as to the food antigen beta-lactoglobulin. Furthermore, the general cytokine profile of the Pa recipients was strongly Th2-skewed at 6 months, as indicated by the cytokines induced by the mitogen phytohaemagglutinin. These data demonstrate that the cytokine profile of 6-month-old infants is influenced by the type of formulation of the pertussis vaccine they received at 2, 3 and 4 months of life. Large prospective studies would be warranted to evaluate the possible long-term consequences of this early modulation of the cytokine responses in infants.

Adhesins, Bacterial↗
PubMed2006

Localized deposition of coronene molecules on Si(001)-2x1 using a scanning tunneling microscope tip source.

The deposition of coronene molecules from scanning tunneling microscope (STM) tips onto a clean Si(001)-2x1 surface at 25 degrees C was investigated. The STM tips, contaminated with coronene, were found to deposit coronene molecules on the clean Si(001) surface, allowing patterns to be generated. Covalent Si-C chemical bonds, formed between the coronene molecules and the Si substrate, froze the flip-flop motion of the adjacent Si-Si dimers on the substrate. In most cases, the mode of coronene bonding to Si(001) is independent of whether deposition occurs from the gas phase or from the STM tip. Despite the covalent chemical bonds formed between the coronene molecule and the Si substrate, the STM tip can drag the coronene laterally on the Si substrate without inducing a chemical change in the molecule. Sharp spikes observed in the tunneling current during the coronene deposition reflect the abrupt decrease of the tip-substrate distance at the instant of transport of the molecule from tip to surface.

Journal Article↗
PubMed2006

Broth cultures yield vs traditional approach in the workup of infectious keratitis.

PURPOSE: To elucidate whether BACTEC Peds Plus F broth, usually used for culturing body fluids in paediatric departments, can be used for corneal cultures from cases with clinically suspected infectious keratitis, and to compare yields between this method and traditional methods (blood agar, chocolate agar, a fungal media, and swab transport media). METHODS: All cases with newly diagnosed, nonviral, clinically suspected infectious keratitis with no prior antibiotic therapy, were cultured both in the BACTEC Peds Plus F broth and the traditional method. McNemar's test was used for pairwise comparisons of the rates of positive growth between the two groups. RESULTS: In total, 30 eyes were included in this study. The growth rates for the traditional method and the BACTEC broth were similar (50.0 and 53.33%, respectively, P=1.0). The overall growth rate for the two methods combined was 73.33%, which is 45.29% higher than the reported yield in the literature (average of 50.47%). CONCLUSIONS: Our results show that BACTEC Peds Plus F broth can be used successfully in the work-up of clinically suspected infectious keratitis. The method has, apparently, several advantages over the 'Traditional method:' time-savings, as only one medium needs to be inoculated, transportation to the laboratory is simpler as there is no need for immediate incubation, and there is no need to keep and maintain a supply of fresh agar media. This method is especially suitable for office settings and remote clinics, but also can be used in hospital setting, as an adjunct, when available, to increase the growth yield.

Agar↗
PubMed2006

Central corneal thickness and its relationship to the patient's origin.

OBJECTIVES: To report central corneal thickness (CCT) measurements on patients requesting refractive surgery and to search for possible associations between CCT and patient's origin, age, sex, and preoperative data. SETTING: Department of Ophthalmology, Soroka University Medical Center, and Enaim Refractive Center, Beer-Sheva, Israel. METHODS: Subjects were patients undergoing preoperative examination at our refractive centre during 2003. Patient's age, sex, preoperative CCT, refractive status, keratometry, and intraocular pressure (IOP) were obtained together with country of origin of the patients and their parents. Main outcome measures were CCT measurements and relationship between CCT and patient's origin and preoperative data. RESULTS: A total of 204 patients were included in the study. Patients of North African origin had statistically significantly thinner corneas than patients of other origins (518.9+/-31.5 vs. 545.4+/-30.4 microm in the right eye and 518.4+/-32.1 vs. 546.3+/-29.7 microm in the left eye; P<0.00001). Patients of North African origin were significantly older than patients of other origins (P=0.028). No differences were found when comparing for sex, intraocular pressure, refractive status, and keratometry. When multivariate analysis was performed patient's origin was the only independently associated factor associated with CCT. CONCLUSIONS: This is the first work in reporting lower CCT in people of North African origin examined in a refractive surgery centre. Studies from similar populations are needed to confirm our results.

Adolescent↗
PubMed2006

Effects of care pathways on stroke care practices at regional hospitals.

BACKGROUND: Our previous work identified deficiencies in stroke care practices at regional hospitals in comparison to standards suggested by published stroke care guidelines. These deficiencies might be improved by the implementation of clinical pathways. The aim of this study was to assess changes in acute stroke care practices following the implementation of stroke care pathways at four regional Queensland hospitals. METHODS: The medical records of two cohorts of 120 patients with a discharge diagnosis of stroke or transient ischaemic attack were retrospectively audited before and after implementation of stroke care pathways to identify differences in the use of acute interventions, investigations and secondary prevention strategies. RESULTS: Following pathway implementation there were clinically important, but not statistically significant, increases in the rates of swallow assessment, allied health assessment (significant for occupational therapy, P = 0.04) and use of deep vein thrombosis prevention strategies (also significant, P = 0.006). Fewer patients were discharged on no anti-thrombotic therapy (statistically significant in the subgroup of patients with atrial fibrillation, P = 0.02). Only 37% of the patients audited were actually enrolled on the pathway. Among this subgroup there were significant increases in the rates of swallow assessment (first 24 h, P = 0.01; any time during admission, P = 0.0001), allied health assessments (all P < 0.05), estimation of blood glucose level (P = 0.0015) and the use of deep vein thrombosis prevention strategies (P = 0.0003). CONCLUSION: Stroke care pathways appear to improve the process of care. Whether this influences outcomes such as mortality, functional and neurological recovery, the incidence of complications, length of stay or the cost of care was beyond the scope of this study and will require further examination.

Adult↗
PubMed2006

[Vaccine prevention of Rotavirus infection].

Two new life attenuated vaccines have been granted this year a marketing authorization by European and American regulatory agencies. One, Rotarix, is a monovalent vaccine derived from a human strain and takes advantage of the cross-reactivity between human Rotavirus strains. The other, RotaTeq, is a pentavalent human-bovine reassortant. These 2 vaccines have been shown to have an excellent safety profile in clinical trials and are highly effective in protecting infants against severe manifestations of Rotavirus gastroenteritis. In industrialized countries, the incidence of Rotavirus infection has not been reduced by the improvement of economic and sanitary conditions and are still associated with severe morbidity and an important economic impact. When they are administered at the same time as DTPa-VHB-IPV/Hib and Pn7V vaccines, they do not interfere with the immune response against the 7 valencies included in these vaccines. The widespread use of these vaccines should allow to control Rotavirus infections in the European context.

Humans↗
PubMed2005

Brain stimulation and morphine reward deficits in dopamine D2 receptor-deficient mice.

RATIONALE: The rewarding effects of lateral hypothalamic brain stimulation, various natural rewards, and several drugs of abuse are attenuated by D1 or D2 dopamine receptor (D1R or D2R) antagonists. Much of the evidence for dopaminergic involvement in rewards is based on pharmacological agents with limited or "relative" selectivity for dopamine receptor subtypes. Genetically engineered animal models provide a complementary approach to pharmacological investigations. OBJECTIVES: In the present study, we explored the contribution of dopamine D2Rs to (1) brain stimulation reward (BSR) and (2) the potentiation of this behavior by morphine and amphetamine using D2R-deficient mice. METHODS: Wild-type (D2Rwt), heterozygous (D2Rhet), and D2R knockout (D2Rko) mice were trained to turn a wheel for rewarding brain stimulation. Once equivalent rate-frequency curves were established, morphine-induced (0, 1.0, 3.0, and 5.6 mg/kg s.c.) and amphetamine-induced (0, 1.0, 2.0, and 4.0 mg/kg i.p.) potentiations of BSR were determined. RESULTS: The D2Rko mice required approximately 50% more stimulation than the D2Rwt mice did. With the equi-rewarding levels of stimulation current, amphetamine potentiated BSR equally across the three genotypes. In contrast, morphine potentiated rewarding stimulation in the D2Rwt, had no effect in the D2Rhet, and antagonized rewarding stimulation in the D2Rko mice. CONCLUSIONS: D2R elimination decreases, but does not eliminate, the rewarding effects of lateral hypothalamic stimulation. After compensation for this deficit, amphetamine continues to potentiate BSR, while morphine does not.

Amphetamine↗
PubMed2005

Intraocular pressure during haemodialysis: a review.

OBJECTIVES: Although several works in the past have examined the effect of haemodialysis (HD) on intraocular pressure (IOP), reported findings, theories, and conclusions are very different. The objectives of this article are to resume the reported evidence of IOP changes during HD, to review the proposed hypothesis of HD influence on IOP, and to determine if ophthalmic examination is imperative in HD patients. METHODS: We analysed the peer-reviewed English literature and selected all possible relevant articles. RESULTS: The influence of HD on IOP is not clear, and even in recent studies opposite findings can be found. CONCLUSIONS: Future studies are needed to clarify the effects of HD on IOP. In patients with glaucoma or with predisposed narrow angles, or eyes with impaired aqueous outflow, the possibility of acute IOP rise during HD could be much more frequent than in normal patients. So in these patients, a more strict ophthalmic scheduled examination seems to be feasible.

Glaucoma↗
PubMed2005

Differences in stroke care practices between regional and metropolitan hospitals.

BACKGROUND: A recent audit of stroke care in major Australian metropolitan teaching hospitals showed considerable variation in care practices and uptake of evidence-based therapies. We could find no published data on stroke care practices in regional Australia. AIM: To compare acute stroke care practices at four regional hospitals with a metropolitan teaching hospital with a stroke unit. METHODS: The hospital medical records of 30 consecutive patients at each hospital (total 150 patients), with a discharge diagnosis of stroke, were retrospectively audited to identify differences in stroke care practices, including the use of investigations, acute interventions, and secondary prevention strategies, between the regional and metropolitan, and between smaller (less than 150 stroke admissions annually) and larger (more than 250 admissions annually) hospitals. RESULTS: Patients treated at regional or smaller hospitals were less likely to have a computed tomography head scan within 24 h of admission, carotid duplex, echocardiography, estimations of lipids and glucose, a swallow assessment, involvement of allied health professionals or be prescribed prophylaxis against deep vein thrombosis, compared to patients treated at metropolitan or larger hospitals. CONCLUSIONS: Significant differences in stroke care practices exist between regional/smaller and metropolitan/larger hospitals. Strategies designed to minimize variation in care practices, such as evidence-based care pathways, should be explored.

Adult↗
PubMed2005

Thyroid ophthalmopathy.

Thyroid associated ophthalmopathy (TAO) is an inflammatory orbital disease of autoimmune origin with the potential to cause severe functional and psychosocial effects. It presents one of the most difficult challenges in the clinical practice of ophthalmology. Pathogenesis of the disease is not yet fully understood. It is usually associated with thyroid dysfunction. TAO has a variable clinical presentation; it may cause severe damage to vision and orbital architecture. TAO is the most frequent cause of unilateral or bilateral proptosis in adults. Potential sight-threatening complications include optic neuropathy and severe corneal exposure keratopathy. Most patients do not require specific therapy. Those with moderately severe or severe disease are treated with steroids and/or orbital radiation during the inflammatory phase and surgical therapy during the inactive phase. Decompression may be needed in either phase. Although appropriate treatment can restore near normal function and appearance in most cases, the management of TAO is difficult, controversial, and far from optimal. Disease severity is the key determinant of the indication for therapy, while therapeutic choice depends on inflammatory activity. Clinical management is difficult because no immediate or dramatic cure exists. With appropriate medical and surgical treatment, patients can be restored to normal function and appearance in most cases, but the process to reach this goal will usually be lengthy.

Diagnosis, Differential↗
PubMed2004

Room-temperature ferroelectricity in strained SrTiO3.

Systems with a ferroelectric to paraelectric transition in the vicinity of room temperature are useful for devices. Adjusting the ferroelectric transition temperature (T(c)) is traditionally accomplished by chemical substitution-as in Ba(x)Sr(1-x)TiO(3), the material widely investigated for microwave devices in which the dielectric constant (epsilon(r)) at GHz frequencies is tuned by applying a quasi-static electric field. Heterogeneity associated with chemical substitution in such films, however, can broaden this phase transition by hundreds of degrees, which is detrimental to tunability and microwave device performance. An alternative way to adjust T(c) in ferroelectric films is strain. Here we show that epitaxial strain from a newly developed substrate can be harnessed to increase T(c) by hundreds of degrees and produce room-temperature ferroelectricity in strontium titanate, a material that is not normally ferroelectric at any temperature. This strain-induced enhancement in T(c) is the largest ever reported. Spatially resolved images of the local polarization state reveal a uniformity that far exceeds films tailored by chemical substitution. The high epsilon(r) at room temperature in these films (nearly 7,000 at 10 GHz) and its sharp dependence on electric field are promising for device applications.

Journal Article↗
PubMed2004

A novel lymphocyte signaling defect: trk A mutation in the syndrome of congenital insensitivity to pain and anhidrosis (CIPA).

Congenital insensitivity to pain with anhidrosis is a syndrome characterized by loss of pain and sensation. The condition frequently evolves into deep wounds and prolonged healing times. Anhidrosis is another prominent component of the disorder. Often associated with recurrent episodes of unexplained fever, it can result in patient mortality. Recent investigations point to Trk A, the high affinity receptor for nerve growth factor (NGF), as a candidate for the site of the mutation that causes the disorder. Functional NGF receptors, such as Trk A and the Trk family of tyrosine kinases, are essential for NGF signaling of human lymphocytes. In this study, we demonstrated that the presence of a trk A mutation in patient B cells results in a novel lymphocyte signaling defect. In these B cells, NGF failed to induce Trk A phosphorylation, cytoskeleton assembly, or MAP kinase activation. These abnormalities may explain some of the clinical features of the disease.

B-Lymphocytes↗
PubMed2004

The ocular manifestations of Weissenbacher-Zweymuller syndrome.

PURPOSE: Weissenbacher-Zweymuller syndrome (WZS) is an autosomal recessive disorder of delayed skeletal maturation. Its characteristic features include rhizomelic dwarfism with metaphyseal and vertebral changes. It has been challenged whether WZS is a part of the spectrum of Stickler syndrome. We report ocular findings in the largest ever-presented series of patients with WZS. METHODS: Patients underwent a paediatric examination, including assessment of growth and development, genetic work-up and X-ray of vertebra and long bones. All had a complete ophthalmic examination, cycloplegic refraction, and face and body photography. RESULTS: All patients had hypertelorism and protruding eyes. Four patients had refractive errors necessitating optical correction ranging from +3 to -8 D. Two patients had strabismus. None had vitreoretinal degeneration, glaucoma, or cataract. CONCLUSIONS: Ocular manifestations of WZS differ from those in Stickler syndrome, indicating that the two likely represent distinct clinical entities. Strabismus and various refractive errors often accompany WZS. An ophthalmologist should follow children with this disorder from an early age to prevent amblyopia.

Adolescent↗
PubMed2004

Health-seeking patterns for AIDS in Malawi.

Health-seeking practices in Malawi are not well understood and it is not clear where people go for help to manage AIDS symptoms and to receive treatment for AIDS- defining illness. This qualitative study examines the health-seeking practices of families affected by AIDS in rural Malawi. Semi-structured interviews were conducted with family caregivers (N=26) and patients with AIDS symptoms (N=20). Health seeking progressed in three stages: traditional care and treatment by family were used first, followed by remedies from traditional healers. When traditional methods fail and symptoms continue modern treatments from hospitals or clinics were used as a last alternative. We discuss the cultural context of health seeking for HIV/AIDS in Malawi and suggest ways in which traditional practices can be integrated into interventions to improve the quality of care and treatment for people living with AIDS.

Acquired Immunodeficiency Syndrome↗