Biomedical subjects

J Levy

Publications and source records attributed to J Levy.

At least 37 records · Page 2Linked to original sources

PubMed2003

Gigahertz electron spin manipulation using voltage-controlled g-tensor modulation.

We present a scheme that enables gigahertz-bandwidth three-dimensional control of electron spins in a semiconductor heterostructure with the use of a single voltage signal. Microwave modulation of the Landé g tensor produces frequency-modulated electron spin precession. Driving at the Larmor frequency results in g-tensor modulation resonance, which is functionally equivalent to electron spin resonance but without the use of time-dependent magnetic fields. These results provide proof of the concept that quantum spin information can be locally manipulated with the use of high-speed electrical circuits.

Journal Article↗

PubMed2003

Congenital myopathy, recurrent secretory diarrhea, bullous eruption of skin, microcephaly, and deafness: a new genetic syndrome?

We describe three siblings with congenital myopathy, bullous eruption of the skin, secretory diarrhea, apparent zinc deficiency, failure to thrive, deafness, and microcephaly. The parents are not consanguineous and there are no other affected relatives. This new syndrome, which follows an apparent autosomal recessive pattern, appears to be distinct from known syndromes of secretory diarrhea, myopathy, deafness, microcephaly, and zinc deficiency.

Abnormalities, Multiple↗

PubMed2003

Lycopene in serum, skin and adipose tissues after tomato-oleoresin supplementation in patients undergoing haemorrhoidectomy or peri-anal fistulotomy.

Lycopene, the main carotenoid found in tomatoes and tomato-based products, has been reported to be protective against several types of cancer. Assessment of changes in plasma concentration of carotenoids following ingestion of lycopene-rich food sources does not necessarily predict changes in lycopene concentration or distribution of its isomers in other body tissues. Our aim was to determine the relationship between concentrations of lycopene and other tomato carotenoids in human serum and body tissues after tomato-oleoresin supplementation. Tomato lycopene oleoresin (30 mg/d) or a placebo was administered for 1 to 7 weeks to seventy-five volunteers undergoing elective haemorrhoidectomy or peri-anal fistulotomy. Carotenoid concentration and isomer distribution in blood and in the surgically removed skin and adipose tissues was measured by HPLC. The serum concentration of lycopene increased after supplementation from 0.26 (SD 0.12) to 0.52 (SD 0.25) micromol/l (n 35; P<0.0001). In the placebo group (n 40), lycopene serum concentration did not change significantly. Serum lycopene concentration after treatment was 2.2-fold greater in the lycopene group than in the placebo group, a slightly higher ratio than that found in skin and adipose tissue (1.6- and 1.4-fold higher than the placebo, respectively). A significant correlation between serum and tissue concentrations was found for both beta-carotene and lycopene in the placebo group, whereas in the lycopene-supplemented group the correlation between serum and tissues remained the same for beta-carotene but for lycopene was weak. Lycopene supplementation did not significantly change the proportion of all-trans v. cis isomers in the serum and tissues, despite the fact that more than 90 % of the supplemented lycopene was in the all-trans form. These results show that tomato-oleoresin supplementation increases lycopene concentrations in serum and in adipose tissue and skin. The ability to increase lycopene levels in tissues is one of the prerequisites for using it as a food supplement with health benefits.

Adipose Tissue↗

PubMed2003

[The safety of vaccination].

The high standard of safety that is expected from vaccines can only be obtained if these products undergo in depth evaluation of their side effects before marketing authorization is guaranted, as well as post-marketing surveillance and investigation of reported adverse events. The evaluation of the benefit/risk balance of vaccines is a dynamic process, influenced by the residual impact of the target disease and by the existence of alternative preventive or therapeutic approaches. The efforts made to ensure the safety of vaccination must be brought to the attention of the public and the health workers to maintain confidence in this important public health intervention.

Humans↗

PubMed2002

[The safety of vaccination].

Humans↗

PubMed2001

Effects of acyclo-retinoic acid and lycopene on activation of the retinoic acid receptor and proliferation of mammary cancer cells.

The biochemical mechanisms underlying the inhibitory effects of lycopene, the main tomato carotenoid, on the growth of cancer cells are largely unknown. It has been hypothesized that lycopene derivatives may act as ligands for a nuclear receptor in analogy to retinoic acid, the hormone derived from beta-carotene. The inhibition of human mammary cancer (MCF-7) cell growth and the transactivation of the retinoic acid receptor (RAR) reporter gene by synthetic acyclo-retinoic acid, the open chain analog of retinoic acid, was compared to the effects of lycopene and retinoic acid in the same systems. Acyclo-retinoic acid activated the DR-5 retinoic acid response element with a approximately 100-fold lower potency than retinoic acid. This effect was independent of cotransfection with the RARalpha receptor. Lycopene exhibited only very modest activity in this system. In contrast to the results from the transactivation studies, acyclo-retinoic acid, retinoic acid, and lycopene inhibited cell growth with a similar potency. Preincubation with each of the three compounds slowed down cell cycle progression from G1 to S phase. In summary, acyclo-retinoic acid inhibited cancer cell growth and interacted with RAR. However, it exhibited low affinity for RAR and a correspondingly low efficacy in activating this receptor, indicating that RAR does not mediate the growth inhibitory effect of the compound. In addition, the concentrations of acyclo-retinoic acid and of lycopene required for inducing inhibition of cell growth were similar, suggesting that acyclo-retinoic acid is unlikely to be the active metabolite of lycopene.

Antineoplastic Agents↗

PubMed2001

Lycopene inhibition of cell cycle progression in breast and endometrial cancer cells is associated with reduction in cyclin D levels and retention of p27(Kip1) in the cyclin E-cdk2 complexes.

Numerous studies have demonstrated the anticancer activity of the tomato carotenoid, lycopene. However, the molecular mechanism of this action remains unknown. Lycopene inhibition of human breast and endometrial cancer cell growth is associated with inhibition of cell cycle progression at the G(1) phase. In this study we determined the lycopene-mediated changes in the cell cycle machinery. Cells synchronized in the G(1) phase by serum deprivation were treated with lycopene or vehicle and restimulated with 5% serum. Lycopene treatment decreased serum-induced phosphorylation of the retinoblastoma protein and related pocket proteins. This effect was associated with reduced cyclin-dependent kinase (cdk4 and cdk2) activities with no alterations in CDK protein levels. Lycopene caused a decrease in cyclin D1 and D3 levels whereas cyclin E levels did not change. The CDK inhibitor p21(Cip1/Waf1) abundance was reduced while p27(Kip1) levels were unaltered in comparison to control cells. Serum stimulation of control cells resulted in reduction in the p27 content in the cyclin E--cdk2 complex and its accumulation in the cyclin D1--cdk4 complex. This change in distribution was largely prevented by lycopene treatment. These results suggest that lycopene inhibits cell cycle progression via reduction of the cyclin D level and retention of p27 in cyclin E--cdk2, thus leading to inhibition of G(1) CDK activities.

Adenocarcinoma↗

PubMed2001

Water water everywhere.

During the last decade of the 20th century the world was exposed to increasing episodes of extreme weather. Figures reveal a 0.6 degrees C rise in average temperatures since records began in 1860, with the 1990s being the warmest decade and 1998 the warmest year. Experts believe that these rising temperatures, or global warming, are in part due to human influences.

Animals↗

PubMed2001

Oral poliomyelitis vaccine: time to change?

For 3 decades, vaccination against poliomyelitis has rested mainly on the use of the oral attenuated vaccine (OPV). In countries where wild type poliomyelitis has been successfully controlled by OPV, the rare cases of poliomyelitis that can still be identified occur in vaccinees or their contacts and are caused by vaccine related strains. Over years, data indicating that the inactivated vaccine (IPV) also has the potential to control poliomyelitis and that there are no known risks associated with the use of this vaccine have accumulated. The reasons for changes in vaccine policy in industrialised countries and the situation of the global effort of poliomyelitis immunisation are described. Some of the issues and challenges for the future are reviewed.

Health Policy↗

PubMed2001

Cbl associates with Pyk2 and Src to regulate Src kinase activity, alpha(v)beta(3) integrin-mediated signaling, cell adhesion, and osteoclast motility.

The signaling events downstream of integrins that regulate cell attachment and motility are only partially understood. Using osteoclasts and transfected 293 cells, we find that a molecular complex comprising Src, Pyk2, and Cbl functions to regulate cell adhesion and motility. The activation of integrin alpha(v)beta(3) induces the [Ca(2+)](i)-dependent phosphorylation of Pyk2 Y402, its association with Src SH2, Src activation, and the Src SH3-dependent recruitment and phosphorylation of c-Cbl. Furthermore, the PTB domain of Cbl is shown to bind to phosphorylated Tyr-416 in the activation loop of Src, the autophosphorylation site of Src, inhibiting Src kinase activity and integrin-mediated adhesion. Finally, we show that deletion of c Src or c-Cbl leads to a decrease in osteoclast migration. Thus, binding of alpha(v)beta(3) integrin induces the formation of a Pyk2/Src/Cbl complex in which Cbl is a key regulator of Src kinase activity and of cell adhesion and migration. These findings may explain the osteopetrotic phenotype in the Src(-/-) mice.

CSK Tyrosine-Protein Kinase↗

PubMed2001

Tangled1: a microtubule binding protein required for the spatial control of cytokinesis in maize.

Spatial control of cytokinesis in plant cells depends on guidance of the cytokinetic apparatus, the phragmoplast, to a cortical "division site" established before mitosis. Previously, we showed that the Tangled1 (Tan1) gene of maize is required for this process during maize leaf development (Cleary, A.L., and L.G. Smith. 1998. Plant Cell. 10:1875-1888.). Here, we show that the Tan1 gene is expressed in dividing cells and encodes a highly basic protein that can directly bind to microtubules (MTs). Moreover, proteins recognized by anti-TAN1 antibodies are preferentially associated with the MT-containing cytoskeletal structures that are misoriented in dividing cells of tan1 mutants. These results suggest that TAN1 protein participates in the orientation of cytoskeletal structures in dividing cells through an association with MTs.

Cell Division↗

PubMed2001

Availability and quality of industry and occupation information in the Massachusetts Cancer Registry.

BACKGROUND: Industry and occupation (I/O) data from state cancer registries can be useful in generating and evaluating hypotheses about occupational cancer risks. The quality of these data is uncertain. METHODS: We reviewed medical records on 1,020 cases from the Massachusetts Cancer Registry (MCR). We compared the presence and detail of I/O data from this dedicated record review (DRR) with routine reporting to the MCR in order to evaluate the potential to increase the availability of I/O data. RESULTS: Compared to routine reporting, the DRR increased the percentage of codable I/O data from 63.6 to 80.4%. The DRR also provided more detail in existing codes in 15.4% of cases. Other sections of the medical record in addition to the face sheet and sections of the record from the period before cancer diagnosis were important sources of additional information. Duration and timing of the corresponding I/O information were rarely recorded. CONCLUSIONS: The nearly one-third (32%) of records that had some improvement in I/O information with a dedicated review indicates considerable opportunity to improve the utility of this resource.

Adolescent↗

PubMed2001

Attitude of Belgian pediatricians toward strategy in acute pyelonephritis.

To investigate the attitude of Belgian pediatricians toward the management and treatment of children with suspected acute pyelonephritis, a short letter was sent to all Belgian pediatricians (1,200). It contained a brief description of a clinical case strongly suggestive of acute pyelonephritis followed by a series of questions centered on complementary examinations to be performed, need of hospitalization and treatment. A total of 583 responses were received (49%). In the acute phase, 99% of pediatricians perform urine cultures, 87% blood examinations, and 76% renal ultrasound. Dimercaptosuccinate (DMSA) scintigraphy is performed during the acute phase by 37% and during follow-up by 32% of all pediatricians. A voiding cystogram is requested by 71%. Ambulatory treatment is considered by 30% of responders. Amoxicillin/clavulanic acid (44%) and trimethoprim/sulfonamide (22%) are the most frequently used oral antibiotics. Private pediatricians perform fewer examinations and more frequently consider ambulatory treatment of acute pyelonephritis, compared to pediatricians working in hospitals. Among Belgian pediatricians, attitudes toward the diagnosis and treatment of acute pyelonephritis are heterogeneous. This survey underlines the need for properly documented prospective studies for the evaluation of different treatment modalities in childhood acute pyelonephritis.

Acute Disease↗

PubMed2001

Treatment of children with acute pyelonephritis: a prospective randomized study.

The aim of this study was to compare, in children with acute pyelonephritis, the efficacy of 7 days' (group A) and 3 days' (group B) intravenous antibiotics, both followed by an oral treatment. Children were randomized after 3 days of intravenous treatment. Technetium-99m dimercaptosuccinic acid (DMSA) scintigraphy was performed within the first days after admission and repeated 6 months later. Total or partial persistence of renal abnormalities on the 6-month DMSA scintigraphy was used as the endpoint of the study. Among the 92 children included in the study, 87 were followed for at least 6 months (43 in group A and 44 in group B) and were eligible for analysis. Late DMSA was abnormal in 9 kidneys of group A and 12 kidneys of group B, representing respectively 24% and 44% of kidneys with abnormalities on the initial DMSA (difference statistically not significant). When the patients were stratified according to the delay of treatment, the percentage of patients with sequelae in group A was comparable, whether the delay was less or more than 1 week. In group B, the percentage of patients with sequelae was significantly higher (P<0.01) when the delay was more than 1 week.

Acute Disease↗

PubMed2001

Neurophysiologic studies in congenital insensitivity to pain with anhidrosis.

Thirteen patients with congenital insensitivity to pain and anhidrosis, carrying a mutation at the TRK-A gene, were studied. Neurologic examination revealed vestigial pain sensitivity, suggesting an incomplete involvement of the affected nerves. All 13 patients manifested normal electrophysiologic studies but striking absence of sympathetic skin responses. We suggest the use of the sympathetic skin response test in the clinical evaluation of patients suspected of having congenital insensitivity to pain and anhidrosis.

Child↗

PubMed2001

Community-acquired bacteremia among hospitalized children in rural central Africa.

OBJECTIVE: To describe the epidemiology of community-acquired bacteremia in children admitted to a rural hospital in central Africa and to identify useful diagnostic signs or symptoms. METHODS: On admission, a blood culture was obtained from all children admitted to Children's Hospital of Lwiro between 1989 and 1990. Clinical and biologic signs of infection and nutritional status were recorded. RESULTS: Among the 779 children included in the study, 15.9% were bacteremic on admission. The rate of bacteremia was the highest among children with jaundice (20/56; 35.7%) and fever (119/487; 24.4%). In contrast, children with severe malnutrition had a lower rate of bacteremia (13.2%) than weight growth retarded or well-nourished children (19.5%) (P = 0.046). Fever was the most useful diagnostic criteria (sensitivity and negative predictive value of 96.0% and 97.8%, respectively) even in severely malnourished children (sensitivity and negative predictive value of 96.4% and 99.1%, respectively). Enterobacteriacea, mostly Salmonella spp, caused 73% of the bacteremia. There was a high rate of resistance to ampicillin and chloramphenicol among the responsible organisms. Only 31 (47.7%) of 65 bacteremic children responded to the combination of ampicillin and gentamicin. The presence of bacteremia on admission did not significantly increase the risk of morality during hospitalization (19.4% compared with 13.5%; P = 0.088). Age less than 12 months and jaundice were independent risk factors for deaths in bacteremic children. CONCLUSIONS: Community-acquired bacteremia caused by multiresistant Enterobacteriacea is an important problem of hospitalized well-nourished and malnourished children in central Africa. Fever on admission is a sensitive diagnostic sign, even in malnourished children.

Bacteremia↗

PubMed2001

Toxic effects of subconjunctival 5-fluorouracil and mitomycin C on ciliary body of rats.

PURPOSE: The effects of subconjunctival injection of mitomycin C and different concentrations of 5-fluorouracil on the epithelium of the ciliary body of twenty Sprague Dawley SD rats was studied. METHODS: Twenty rats were divided into four treatment groups. The first three groups received 0.2 ml of 5, 10, and 30 mg of 5-fluorouracil subconjunctivally respectively, and the fourth group 0.2 ml of 0.4 mg/ml mitomycin C subconjunctivally. The right eye received 0.2 ml of the antimetabolite, while the left eye was injected with 0.2 ml of saline subconjunctivally, as a control. The eyes were examined histologically, in a masked fashion, by light and by transmission electron microscopy. In each treatment group, two eyes were examined after one week, and three eyes were examined one month after the subconjunctival injection. RESULTS: Electron microscopy revealed toxic effects in the epithelium of the ciliary body of all treatment groups. The 5-fluorouracil group revealed focal mitochondrial edema, enlargement of intercellular spaces, and dilatation of intracellular spaces. The mitomycin C group showed pyknotic nuclei, enlargement of intercellular spaces, and irregular flattened epithelial cells. The severity of changes correlated with concentration and length of exposure. No pathology was found by light microscopy in all groups. CONCLUSIONS: This study demonstrates that subconjunctival antimetabolites mitomycin C and 5-fluorouracil can penetrate the sclera and exert toxic effects on the epithelium of the ciliary body, even in low doses. These changes were only apparent by electron microscopy and were still present one month after the injection. These findings may contribute to the theory that the application of antimetabolites during or after surgery has a direct effect on the epithelium of the ciliary body, besides its known effect on the conjunctiva. Further studies are needed to evaluate its effect on intraocular pressure.

Animals↗

PubMed2001

Eyelid fish-hook injury.

OBJECTIVE: To report a rare case of fish-hook eyelid injury. METHODS: Interventional case-report. A 25-year-old man presented with an upper eyelid fish-hook wound. RESULTS: The hook was extracted under local anaesthesia using the back-out method. Postoperatively, no complications were observed. CONCLUSIONS: In the absence of serious ocular damage, the back-out method seems to be the best option for the removal of the hook in eyelid injuries.

Adult↗