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Biomedical subjects

Y Cohen

Publications and source records attributed to Y Cohen.

At least 19 recordsLinked to original sources
PubMed2006

Use of thermal and visible imagery for estimating crop water status of irrigated grapevine.

Achieving high quality wine grapes depends on the ability to maintain mild to moderate levels of water stress in the crop during the growing season. This study investigates the use of thermal imaging for monitoring water stress. Experiments were conducted on a wine-grape (Vitis vinifera cv. Merlot) vineyard in northern Israel. Irrigation treatments included mild, moderate, and severe stress. Thermal and visible (RGB) images of the crop were taken on four days at midday with a FLIR thermal imaging system and a digital camera, respectively, both mounted on a truck-crane 15 m above the canopy. Aluminium crosses were used to match visible and thermal images in post-processing and an artificial wet surface was used to estimate the reference wet temperature (T(wet)). Monitored crop parameters included stem water potential (Psi(stem)), leaf conductance (g(L)), and leaf area index (LAI). Meteorological parameters were measured at 2 m height. CWSI was highly correlated with g(L) and moderately correlated with Psi(stem). The CWSI-g(L) relationship was very stable throughout the season, but for that of CWSI-Psi(stem) both intercept and slope varied considerably. The latter presumably reflects the non-direct nature of the physiological relationship between CWSI and Psi(stem). The highest R(2) for the CWSI to g(L) relationship, 0.91 (n=12), was obtained when CWSI was computed using temperatures from the centre of the canopy, T(wet) from the artificial wet surface, and reference dry temperature from air temperature plus 5 degrees C. Using T(wet) calculated from the inverted Penman-Monteith equation and estimated from an artificially wetted part of the canopy also yielded crop water-stress estimates highly correlated with g(L) (R(2)=0.89 and 0.82, respectively), while a crop water-stress index using 'theoretical' reference temperatures computed from climate data showed significant deviations in the late season. Parameter variability and robustness of the different CWSI estimates are discussed. Future research should aim at developing thermal imaging into an irrigation scheduling tool applicable to different crops.

Air↗
PubMed2006

A prospective, double-blind phase II study evaluating the safety and efficacy of a topical histamine gel for the prophylaxis of oral mucositis in patients post hematopoietic stem cell transplantation.

The aim of this study was to evaluate the safety, tolerability and efficacy of a topical gel containing histamine dihydrochloride (HDC) versus a placebo gel in preventing oral mucositis in hematopoietic stem cell transplantation (HSCT) patients. A total of 45 patients post-HSCT were enrolled in a prospective longitudinal, placebo-controlled, double-blind study. Patients were evaluated twice weekly for oral mucositis (OMAS, NCI score), oral pain (VAS), oral function and salivary flow rate. Compliance was assessed using a patient diary. Oral mucositis developed in 85% of the HDC group and 63% of the placebo group. The mean maximal intensity for NCI score was 1.45+/-1 in the HDC group and 1.21+/-1.27 in the placebo group (P=0.37). The mean duration of oral mucositis was 4.7+/-3.6 and 2.33+/-2.23 days in the HDC and placebo groups, respectively (P=0.06). The same trends were measured with OMAS. Visual analogue scale for oral pain and oral function was not significantly different between the two groups. Histamine dihydrochloride was found to be safe. In the search for topical agents for the prevention of mucositis, we found that HDC neither improves nor worsens oral mucositis in HSCT patients. The balance between the pro- and anti-inflammatory effects of HDC should be investigated further in order to acquire a clinically effective topical medication based on its anti-inflammatory properties.

Aged↗
PubMed2005

Development of a tissue-engineered composite implant for treating traumatic paraplegia in rats.

This study was designed to assess a new composite implant to induce regeneration of injured spinal cord in paraplegic rats following complete cord transection. Neuronal xenogeneic cells from biopsies of adult nasal olfactory mucosa (NOM) of human origin, or spinal cords of human embryos, were cultured in two consecutive stages: stationary cultures in a viscous semi-solid gel (NVR-N-Gel) and in suspension on positively charged microcarriers (MCs). A tissue-engineered tubular scaffold, containing bundles of parallel nanofibers, was developed. Both the tube and the nanofibers were made of a biodegradable dextran sulphate-gelatin co-precipitate. The suturable scaffold anchored the implant at the site of injury and provided guidance for the regenerating axons. Implants of adult human NOM cells were implanted into eight rats, from which a 4 mm segment of the spinal cord had been completely removed. Another four rats whose spinal cords had also been transected were implanted with a composite implant of cultured human embryonic spinal cord cells. Eight other cord-transected rats served as a control group. Physiological and behavioral analysis, performed 3 months after implantation, revealed partial recovery of function in one or two limbs in three out of eight animals of the NOM implanted group and in all the four rats that were implanted with cultured human embryonic spinal cord cells. Animals of the control group remained completely paralyzed and did not show transmission of stimuli to the brain. The utilization of an innovative composite implant to bridge a gap resulting from the transection and removal of a 4 mm spinal cord segment shows promise, suggesting the feasibility of this approach for partial reconstruction of spinal cord lesions. Such an implant may serve as a vital bridging station in acute and chronic cases of paraplegia.

Animals↗
PubMed2005

Estimation of leaf water potential by thermal imagery and spatial analysis.

Canopy temperature has long been recognized as an indicator of plant water status and as a potential tool for irrigation scheduling. In the present study, the potential of using thermal images for an in-field estimation of the water status of cotton under a range of irrigation regimes was investigated. Thermal images were taken with a radiometric infrared video camera. Specific leaves that appeared in the camera field of view were sampled, their LWP was measured and their temperature was calculated from the images. Regression models were built in order to predict LWP according to the crop canopy temperature and to the empirical formulation of the crop water stress index (CWSI). Statistical analysis revealed that the relationship between CWSI and LWP was more stable and had slightly higher correlation coefficients than that between canopy temperature and LWP. The regression models of LWP against CWSI and against leaf temperatures were used to create LWP maps. The classified LWP maps showed that there was spatial variability in each treatment, some of which may be attributed to the difference between sunlit and shaded leaves. The distribution of LWP in the maps showed that irrigation treatments were better distinguished from each other when the maps were calculated from CWSI than from leaf temperature alone. Furthermore, the inclusion of the spatial pattern in the classification enhanced the differences between the treatments and was better matched to irrigation amounts. Optimal determination of the water status from thermal images should be based on an overall view of the physical status as well as on the analysis of the spatial structure. Future study will involve investigating the robustness of the models and the potential of using water status maps, derived from aerial thermal images, for irrigation scheduling and variable management in commercial fields.

Agriculture↗
PubMed2005

[Remifentanil-midazolam compared to sufentanil-midazolam for ICU long-term sedation].

OBJECTIVE: Remifentanil has a unique metabolic pathway that holds potential benefits for long-term sedation. We compared remifentanil-midazolam to sufentanil-midazolam in 41 critically ill adults requiring mechanical ventilation. STUDY DESIGN: Randomized double-blind trial. PATIENTS AND METHODS: Infusion rates were titrated every 4 hours to achieve the desired Ramsay score. Five fold increases in dose requirement was considered as the development of tolerance. Drugs requirement, development of tolerance and weaning time of ventilation were compared. RESULTS: The study was stopped after an interim analysis. The remifentanil and sufentanil groups were comparable regarding IGS II: 56+/-22 vs 64+/-26, mean+/-SD, ICU length of stay: 26 (8-45) vs 19 (11-34) days, and sedation duration: 6 (4-19) vs 6 (3-16)days, median [interquartile range, IQR]). There was a shorter weaning time in the remifentanil group as compared to sufentanil group: 22 h (12-53) vs 96 (47-142) h, median [IQR], p=0.04). The daily opioid infusion rate needed to be decreased over time only in sufentanil group, p < 0.001. Tolerance occurred in 6 (30%; CI(95), 10 to 40%) remifentanil and no sufentanil patients (P=0.02). CONCLUSION: Sufentanil infusion needed to be reduced over time and prolonged the weaning time when compared to remifentanil.

Adult↗
PubMed2005

Cutaneous photosensitivity induced by paclitaxel and trastuzumab therapy associated with aberrations in the biosynthesis of porphyrins.

BACKGROUND: Paclitaxel and trastuzumab are new treatments for patients with metastatic breast cancer. CASE REPORT: We describe here a 40-year-old female patient with metastatic breast cancer who developed a photosensitive rash 1 month after initiation of paclitaxel and trastuzumab therapy. The eruption appeared on the dorsal aspect of her hands, forearms, legs and face and consisted of erythema, edema and vesicles, and was associated with distal onycholysis. Aberrations in various parameters of the metabolism of porphyrins were observed in urine and erythrocytes. Sun avoidance and withdrawal of paclitaxel was followed by resolution of the rash and a return to the normal pattern of porphyrins biosynthesis. CONCLUSION: The combination of paclitaxel and trastuzumab treatment and sun exposure may induce a photosensitive reaction, associated with changes in various parameters of porphyrins biosynthesis.

Adult↗
PubMed2005

Insulin pump therapy vs. multiple daily injections in obese Type 2 diabetic patients.

AIMS: To compare the efficacy of insulin pump treatment with multiple daily injections in the treatment of poorly controlled obese Type 2 diabetic patients already receiving two or more daily injections of insulin plus metformin. METHODS: Forty obese Type 2 diabetic subjects (using insulin) were randomized to treatment with continuous subcutaneous infusion pump (CSII) (Minimed) or multiple daily insulin injections (MDI). At the end of the first 18-week treatment period, patients underwent a 12-week washout period during which they were treated with MDI plus metformin. They were then crossed-over to the other treatment for an 18-week follow-up period. Patients performed 4-point daily self blood-glucose monitoring (SBGM) on a regular basis and 7-point monitoring prior to visits 2, 8, 10 and 16. A subset of patients underwent continuous glucose monitoring using the Minimed(R) continuous glucose monitoring system (CGMS) at visits 2, 8, 10 and 16. A standard meal test was performed in which serum glucose was tested at fasting and once each hour for 6 h following a test meal. Glucose levels were plotted against time and the area under the curve (AUC) was calculated. HbA(1c), weight, daily insulin dose and hypoglycaemic episodes were recorded. RESULTS: In obese Type 2 diabetic patients already treated with insulin, treatment with CSII significantly reduced HbA(1c) levels compared with treatment with MDI. An additional CSII treatment benefit was demonstrated by reduced meal-test glucose AUC. Initial reduction of daily insulin requirement observed in CSII-treated subjects during the first treatment period was attributable to a period effect and did not persist over time. CONCLUSIONS: In the intent-to-treat analysis, CSII appeared to be superior to MDI in reducing HbA(1c) and glucose AUC values without significant change in weight or insulin dose in obese, uncontrolled, insulin-treated Type 2 diabetic subjects.

Adult↗
PubMed2004

Structure of microemulsions with gemini surfactant studied by solvatochromic probe and diffusion NMR.

The structure of microemulsions prepared by the anionic gemini surfactant didodecyl diphenyl ether disulfonate (C12-DADS) was investigated by a solvatochromic probe and nuclear magnetic resonance (NMR) diffusion measurements. The NMR measurements indicate the presence of bicontinuous and oil-in-water microemulsions depending on microemulsion composition. The absorbance spectra of the solvatochromic probe, Nile red, indicate the solubilization of the probe in different sites, in agreement with the NMR findings. It was also found that the microemulsions were capable of dissolving the hydrophobic probe, Nile red, up to four times better than expected if it were simply dissolved in the toluene phase.

Emulsions↗
PubMed2004

Microstructural characterization of micro- and nanoparticles formed by polymer-surfactant interactions.

We have studied the nano- and microparticles formed by complexation of PDAC [poly(diallyldimethyl-ammoniumchloride)] and SDS (sodium dodecyl sulfate). The complexation phenomenon was characterized by light scattering and zeta-potential measurements. The nature of the complexes was revealed by direct-imaging cryogenic temperature transmission electron microscopy (cryo-TEM), showing nanometric details of the complexes formed around the point of neutralization. The images also reveal how those aggregates are solubilized by excess surfactant, first into faceted particles with threadlike micelles attached to their surfaces, prior to complete solubilization, then into lacelike aggregates, and finally into spheroidal micelles. The nanostructure of the complexes strongly suggests they are made of a hexagonal liquid crystalline phase. This was further supported by small-angle X-ray scattering (SAXS).

Journal Article↗
PubMed2004

Sedation, sucralfate, and antibiotic use are potential means for protection against early-onset ventilator-associated pneumonia.

To examine risk factors for early-onset ventilator-associated pneumonia (EOP) in patients requiring mechanical ventilation (MV), we performed a prospective cohort study that included 747 patients. Pneumonia was defined as a positive result for a protected quantitative distal sample. EOP was defined as pneumonia that occurred from day 3 to day 7 of MV. Eighty patients (10.7%) experienced EOP. Independent predictors of EOP were male sex (odds ratio [OR], 2.06; 95% confidence interval [CI], 1.18-3.63), actual Glasgow Coma Scale value of 6-13 (OR, 1.95; 95% CI, 1.2-3.18), high Logistic Organ Dysfunction score at day 2 (OR, 1.12 per point; 95% CI, 1.02-1.23), unplanned extubation (OR, 3.19; 95% CI, 1.28-7.92), and sucralfate use (OR, 1.81; 95% CI, 1.01-3.26). Protection occurred with use of aminoglycosides (OR, 0.36; 95% CI, 0.17-0.76), beta -lactams and/or beta -lactamase inhibitors (OR, 0.47; 95% CI, 0.28-0.83), or third-generation cephalosporins (OR, 0.33; 95% CI, 0.16-0.74). Sucralfate use and unplanned extubation are independent risk factors for EOP. Use of aminoglycosides, beta-lactams/ beta-lactamase inhibitors, or third-generation cephalosporins protects against EOP.

Aged↗
PubMed2004

Spindle imaging: a new marker for optimal timing of ICSI?

BACKGROUND: The LC Polscope facilitates visualization of the meiotic spindle in human oocyte. This study aimed to investigate meiotic spindle assembly in correlation to time elapsed after HCG administration, and to determine whether spindle imaging may serve to indicate the likelihood of fertilization and embryo cleavage. METHODS: Metaphase II (MII) oocytes from 103 couples who were being treated for male infertility were imaged with the Polscope prior to sperm injection. Spindle imaging was correlated to time elapsed from HCG administration, fertilization rate and embryo cleavage. The main outcome measures were spindle visualization, fertilization and embryo cleavage on day 3. RESULTS: A total of 770 MII oocytes were imaged. A spindle was imaged in a significantly higher number of oocytes from >or=38 h after HCG administration compared with those in the <38 h group (78.1-81.5% versus 61.6%; P < 0.001). The fertilization rate in oocytes with a visible spindle was statistically higher compared with oocytes in which spindle could not be detected (70.4% versus 62.2%; P = 0.035). We found no relationship between spindle imaging and embryo cleavage on day 3. CONCLUSIONS: Spindle imaging, in addition to first polar body appearance, is an accurate indicator for oocyte maturity. We suggest that spindle imaging be performed prior to sperm injection.

Biomarkers↗
PubMed2004

N-acetyl functions and acetate detected by nuclear magnetic resonance spectroscopy of urine to detect renal dysfunction following aminoglycoside and/or glycopeptide antibiotic therapy.

BACKGROUND/AIMS: N-acetylneuraminidine (NeuNAc), N-acetylglutamine (GIcNAc) and acetate are metabolites present in normal urine. In patients treated with aminoglycosides and/or glycopeptides, elevation of these metabolites in urine suggests renal tubular injury. NeuNAc, GIcNAc and acetate are easily detected by magnetic resonance spectroscopy (MRS), in contrast to other bioanalytical methods. In the present study, these urinary metabolites were detected using MRS and compared with standard biochemical markers of renal injury in intensive care unit patients treated with aminoglycosides and/or glycopeptides. METHODS: 16 patients with clinical and biochemical signs of renal dysfunction were included in the study. Proton magnetic resonance spectra were obtained from 134 urine samples. The resonance intensity of NeuNAc, GIcNAc and acetate were reported relative to the resonance intensity of creatinine (ct). These ratios were compared with classical parameters of renal dysfunction, such as plasma creatinine and urea concentration, and 24-hour urine volume, by logistic regression and general linear models. RESULTS: Statistical analysis showed that changes in plasma creatinine and urea concentration were reliably reflected in changes in the NeuNAc/ct ratio, and that plasma urea concentration changes also correlated with the acetate/ct ratio; however, the GIcNAc/ct ratio was not related to these measures of overall renal function. CONCLUSIONS: NeuNAc/ct may be a useful marker of renal dysfunction in patients treated with aminoglycosides and glycopeptides; by MRS it can be both straightforward and informative to follow the renal function of patients treated with these antibiotics.

Acetates↗
PubMed2003

Prognosis and outcome of 26 patients with systemic necrotizing vasculitis admitted to the intensive care unit.

OBJECTIVES: To investigate presenting features, prognostic factors and outcomes of patients with systemic necrotizing vasculitis (SNV) admitted to the intensive care unit (ICU). METHODS: We retrospectively reviewed the medical records of all 210 SNV patients followed in our university hospital and admitted to the ICU between 1982 and 2001, with respect to clinical features, ICU disease severity scores (APACHE II and SAPS II), the Birmingham vasculitis activity score (BVAS), the five-factors score (FFS) and outcomes. RESULTS: Twenty-six patients (16 men, 10 women) with a mean age of 46.3+/-16.5 yr were included. The reasons for ICU admission were: active SNV, 20 (77%); infection, 3 (12%); others, 3 (12%). SNV was diagnosed in 11 (42%) patients in the ICU. The mean APACHE II and SAPS II scores were significantly higher for patients who died in the ICU (P = 0.01 and P = 0.01 respectively). After a mean follow-up of 31.4+/-29.2 months, the overall mortality rate was 39% (10 patients). Among patients admitted to the ICU with active SNV, BVAS calculated at ICU admission was significantly higher for non-survivors at the end of follow-up (26.9+/-13.0 vs 14.7+/-4.6, P = 0.02). CONCLUSION: The main reason for admitting SNV patients to the ICU was active vasculitis, which was often the first manifestation of SNV and led to its diagnosis. ICU disease severity scores at admission were associated with mortality in the ICU but did not predict long-term outcome, unlike BVAS, which accurately predicted long-term outcome but not ICU prognosis for patients admitted to the ICU with active SNV.

Adolescent↗
PubMed2003

[Infections by Candida sp. in intensive care. Survey of French practices].

OBJECTIVE: The isolation of Candida sp in nosocomial infections is on the increase and over the past 10 years many guidelines for "good" practices and recommendations have been published on the modalities for the management of systemic candidiasis. The aim of this paper was to assess the habits in the intensive care units in this domain in France. METHOD: A transversal survey on the habits was conducted from March to May 2001, using a questionnaire mailed to 200 intensive care units. RESULTS: One hundred eighty questionnaires (surgical reanimation: 12%, medical: 18%, medico-surgical: 70%) out of 200 (92.5%) were returned. The indirect diagnostic examinations: serology, search for antigenemia and PCR (Polymerase Chain Reaction) were never used in 21, 35 and 65% of cases. The systematic search for colonisation (a mean of 4 areas sampled) was conducted in all the patients by 19% of the investigators, in some patients by 53%, and never by 28%. An antifungal treatment was prescribed: in the presence of a positive haemoculture alone, once out of twice if the sample had been taken from a central catheter and in 2 cases out of 3 when the sample was peripheral. It was prescribed 6 times out of 10 after isolation of Candida sp following surgery or on needle aspiration of an intra-abdominal abscess, varyingly in the case of cadiduria, isolation of a Candida sp in a broncho-pulmonary sample or in abdominal draining and positive culture of a catheter, depending on the intensity of the colonisation, the severity of the clinical picture and the presence of factors of risk for Candida infection. It is still prescribed empirically depending on the same elements and the absence of explanation for worsening. When faced with candidemia in a non-neutropenic patient, a central catheter is not changed in 18% of cases. Depending on the microbiology, fluconazole is prescribed in: the identification of yeast without further precision (78% of cases), Candida sp without further precision (86% of cases), Candida non albicans without further precision (57% of cases), C. albicans (93% of cases), Candida non albicans other than C. krusei and C. glabrata (62% of cases), C. glabrata (36% of cases) with an increase in dose in 1 out of 2 cases. In the presence of C. glabrata or C. krusei, amphotericin B is the choice in respectively 51 and 75% of cases. To adapt the treatment.

Adult↗
PubMed2003

Adjuvant treatment of high-risk stage II breast cancer with doxorubicin followed by high-dose chemotherapy and autologous stem-cell transplantation: a single-institution experience with 132 consecutive patients.

Several studies have shown conflicting results with the use of intensive consolidation chemotherapy for breast cancer. The aim of the present study was to investigate the efficacy, feasibility and toxicity of high-dose chemotherapy with stem cell support in patients with high-risk stage II breast cancer. From February 1994 to November 1998, 132 consecutive patients with multinode positive breast cancer were entered to the study. In total, 86 patients had >or=10 positive axillary lymph nodes, and 46 had 4-9 positive axillary lymph nodes with at least two additional predetermined risk factors at diagnosis. All patients were offered adjuvant chemotherapy (doxorubicin, 75 mg/m(2) x 4) followed by high-dose chemotherapy (cyclophosphamide 6000 mg/m(2), carboplatin 800 mg/m(2) and thio-tepa 500 mg/m(2)) and autologous stem cell support with growth factor. In all, 131 patients also received local radiation therapy and tamoxifen based on receptor status. After a median follow-up of 51 months (range 27-87), the disease-free and overall survival rates were 72 and 81%, respectively. There was no difference in the outcome for high-risk patients with > or < than 10 positive axillary lymph nodes. On Cox regression analysis only progesterone receptor status was predictive of disease-free, but not overall survival. There were no treatment-related deaths; grades III-IV toxicity was relatively low. This combined approach of doxorubicin followed by high-dose chemotherapy and stem-cell support, followed by locoregional radiotherapy, was safe and seems to be effective in patients with multinode positive stage II breast cancer. In previous trials of adjuvant high-dose therapy in this patient population, treatment-related morbidity and mortality markedly influenced the outcome. For this high-risk patient population, further testing of intensive chemotherapy regimens with a lower toxicity profile is warranted.

Antineoplastic Agents↗
PubMed2002

High b value q-space-analyzed diffusion MRI in vascular dementia: a preliminary study.

High b value diffusion weighted magnetic resonance imaging (high-b DWI) was used to characterize white matter changes in the brain of patients with vascular dementia (VaD). Hyperintense white matter areas detected by T2-weighted magnetic resonance imaging (MRI) represent lesions, also termed leukoaraiosis that are very common in VaD as well as in other types of dementia. Therefore, the role of white matter changes in the cognitive and memory decline that occurs in VaD patients is still under debate. High-b DWI, analyzed using the q-space approach, is a more sensitive MRI method for detection of white matter changes. High-b DWI revealed massive white matter loss in VaD patients that surpassed the boundaries of T2 hyperintensities. This technique, therefore, might serve as a better indication for the extensive nerve fiber loss in the white matter that is caused by vascular disease.

Aged↗
PubMed2002

High b-value q-space analyzed diffusion-weighted MRI: application to multiple sclerosis.

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS) which affects nearly one million people worldwide, leading to a progressive decline of motor and sensory functions, and permanent disability. High b-value diffusion-weighted MR images (b of up to 14000 s/mm(2)) were acquired from the brains of controls and MS patients. These diffusion MR images, in which signal decay is not monoexponential, were analyzed using the q-space approach that emphasizes the diffusion characteristics of the slow-diffusing component. From this analysis, displacement and probability maps were constructed. The computed q-space analyzed MR images that were compared with conventional T(1), T(2) (fluid attenuated inversion recovery (FLAIR)), and diffusion tensor imaging (DTI) images were found to be sensitive to the pathophysiological state of white matter. The indices used to construct this q-space analyzed MR maps, provided a pronounced differentiation between normal tissue and tissues classified as MS plaques by the FLAIR images. More importantly, a pronounced differentiation was also observed between tissues classified by the FLAIR MR images as normal-appearing white matter (NAWM) in the MS brains, which are known to be abnormal, and the respective control tissues. The potential diagnostic capacity of high b-value diffusion q-space analyzed MR images is discussed, and experimental data that explains the consequences of using the q-space approach once the short pulse gradient approximation is violated are presented.

Animals↗