Search PubMed⌕ Search

Biomedical subjects

D Elad

Publications and source records attributed to D Elad.

At least 73 records · Page 4Linked to original sources
PubMed1995

Feed contamination with Candida krusei as a probable source of mycotic mastitis in dairy cows.

Over 3 months, yeasts were isolated in pure culture from milk samples obtained from 8 lactating cows with acute mastitis and from 1 cow with subacute mastitis. Eight of the isolates were identified as Candida krusei; 1 isolate was not submitted for identification. The affected cows were assigned to separate milking groups and had not been treated by intramammary administration of antibiotic before the outbreak. Remission of disease without treatment was observed, followed by shedding of the yeast in milk for 2 to 5 weeks. Median somatic cell counts in the affected cows before, during, and 2 months after the onset of clinical signs were 93,000; 1,793,000; and 135,000 cells/ml, respectively. Wheat silage was found to be the probable source of the infecting microorganism, whereas inadequate milking hygiene resulted in its persistence in the herd. Following replacement of the silage and improvement of the milking hygiene, the outbreak ceased. Candida krusei thus may cause mastitis in cattle not only following intramammary antibiotic treatment, but also in conditions of heavy environmental contamination, in conjunction with inadequate milking hygiene.

Animal Feed↗
PubMed1995

Immunogenicity in calves of a crude ribosomal fraction of Trichophyton verrucosum: a field trial.

This paper describes a field trial involving 13 calves raised on a farm known to be endemic for Trichophyton verrucosum infection. Seven calves were immunized by subcutaneous inoculations with a crude ribosomal fraction (CRF) of T. verrucosum suspended in aluminium hydroxide as adjuvant. Six animals were sham-immunized with buffer suspended in the adjuvant and served as controls. Two injections were given: one at the age of 2 weeks and a second 2 weeks later. CRF was prepared from T. verrucosum cultures grown in a vitamin-enriched liquid medium. The fungal mat was disrupted mechanically and CRF was separated from the cell-free extract by differential ultracentrifugation. The CRF was characterized biochemically (RNA and protein content) and physically (electron microscopy). The protection induced by vaccination was assessed through a clinical follow-up of the animals to determine the presence and duration of dermatophyte infection following their exposure to a T. verrucosum-contaminated environment. Vaccination with the CRF resulted in a statistically significant decrease in the period during which clinical signs of dermatophytosis were observed (from a mean of 9.5 weeks to 3.7 weeks). To assess the humoral response, serum samples were taken before each vaccination and 2 weeks after the second inoculation. For the cell-mediated immune (CMI) response assessment, whole-blood samples were taken 2 weeks after the second vaccination. The presence of anti-T. verrucosum antibodies in the sera was determined by ELISA and the CMI response was assessed in vitro by the lymphocyte stimulation test.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Skin diseases in a Merino sheep herd related to an excessively rainy winter in a Mediterranean climatic zone.

A retrospective study is presented here in which an outbreak of dermatophilosis and morbidity of fleece rot in a sheep herd grazing throughout the year in the Carmel hills are described for the first time in a Mediterranean climatic zone. Both diseases were closely related to intense and prolonged rains during the winter months of 1991/1992. Morbidity of dermatophilosis appeared after 650 mm and that of fleece rot after 1320 mm of precipitation. The pathogenesis of these diseases is discussed.

Animals↗
PubMed1995

A survey of dermatophilosis in Israeli dairy cattle.

In Israel, dermatophilosis was found to inflict severe lesions, especially in first-calving cows during the first weeks post-parturition. Decreased milk production (by 40% on average) was also noted. Acute exudative dermatitis was observed in these animals. Severely reacting animals (570 in 38 kibbutz herds and 15 animals in 4 family herds) were treated with antibiotics. All these animals also suffered either from endometritis/metritis or mastitis. The "tumoral" form of dermatophilosis was observed on 3-week-old or younger calves. Dermatophilosis was especially prevalent (89.4%) in dairy herds in which intensive showering of lactating cows is practised during the spring and summer months, in comparison to the family herds where the morbidity rate was lower (6.6%). Morbidity rates were found to be higher in the humid Mediterranean Coastal Plain (66.3%) than in the arid or semi-arid regions (Negev and Arava Valley) of Southern Israel (3.7%). Five clinical forms of dermatophilosis and the epizootiological aspects of the disease in Israeli dairy herds are described. It is concluded that a reduction in the prevalence of dermatophilosis could be achieved by decreasing the frequency and the intensity of showering currently applied under the kibbutz management system.

Actinomycosis↗
PubMed1994

Immunogenicity in guinea-pigs of a crude ribosomal fraction from Microsporum canis.

The immunogenicity of a crude ribosomal fraction (CRF) extracted from Microsporum canis was tested by assessing protection of vaccinated guinea-pigs (GP) against a challenge with the dermatophyte. Stimulation of the humoral as well as the cellular immune systems of these animals was evaluated by ELISA and the lymphocyte stimulation tests, respectively. In addition, the immune response elicited by the M. canis CRF was examined for cross-reactivity towards Trichophyton verrucosum antigen. The duration of the infection induced by M. canis in GP was reduced to 8 days in vaccinated animals versus 37 days in the control GP. Both humoral and cellular immune systems were stimulated by the CRF. Sera of GP vaccinated with M. canis CRF revealed presence of anti-T. verrucosum antibodies, albeit at titres significantly lower than against M. canis.

Animals↗
PubMed1994

Hydrodynamic evaluation of intravenous infusion systems.

STUDY OBJECTIVE: We investigated the hydrodynamic characteristics of IV infusion sets for rapid fluid resuscitation. A simple technique has been devised for quantitative evaluation of the hydrodynamic characteristics of IV sets, including their components, for a range of infusion pressures. SETTING AND METHODS: Previous investigations have measured the overall flow rate of infusion sets with and without IV catheters. This study presents a quantitative technique for measuring the resistance to flow of the IV delivery set as a whole as well as its components. An infusion set was measured with 14- and 18-gauge IV catheters while delivering fluid at infusion pressures between 50 (gravity) and 400 mm Hg. MEASUREMENTS AND MAIN RESULTS: At gravity-driven infusion, the drip chamber imposes a resistance to flow of the same order as that of the catheter. At pressurized infusion with small-bore catheters, the catheter consumes the majority of the overall pressure drop. At pressurized infusion with a large-bore catheter or tubing, the standard drip chamber becomes the limiting component and imposes the largest resistance to flow. CONCLUSION: At gravity-delivered pressures (50 and 100 mm Hg), the only effective way of increasing flow rate (more than twofold) is to use a low-resistance drip chamber or to use two infusion sites. At pressurized delivery pressures (more than 200 mm Hg), increasing catheter size from 18 to 14 gauge would be more effective than doubling the number of infusion sets. Also, a more efficient drip chamber adds an important advantage. Finally, increasing the tubing diameter adds only minimal benefit.

Catheterization, Peripheral↗
PubMed1993

An outbreak of Corynebacterium pseudotuberculosis infection in an Israeli dairy herd.

An outbreak of Corynebacterium pseudotuberculosis infection in an Israeli dairy herd appeared in four clinical forms: cutaneous, mastitic, visceral and a mixed form. Only cows were affected and susceptibility increased with age. Most cases occurred during a short period in the summer months. The total morbidity rate was 13.7 per cent involving 41 cows. Thirty cows were affected by the cutaneous form, five by the mastitic form, four by the mastitic and cutaneous forms, one by the mastitic and visceral forms and one by the visceral form. The cutaneous form appeared as one or two pyogranulomatous lesions affecting the body or head. Subclinical to severe clinical mastitis was found in the mastitic form. In the visceral form the upper and lower respiratory system were affected by multiple purulent lymphadenitis. All the cutaneous lesions recovered irrespective of treatment. Mastitis did not respond to treatment and severely affected milk production in most cases. All the isolates of C pseudotuberculosis were nitrate reductase negative. Most isolates were sensitive to norfloxacin, cephalothin, methicillin, kanamycin and furazolidone and resistant to ampicillin, lincomycin and neomycin.

Age Factors↗
PubMed1993

Analysis of air flow patterns in the human nose.

The nasal cavity is the main passage for air flow between the ambient atmosphere and the lungs. A preliminary requisite for any investigation of the mechanisms of each of its main physiological functions, such as filtration, air-conditioning and olfaction, is a basic knowledge of the air-flow pattern in this cavity. However, its complex three-dimensional structure and inaccessibility has traditionally prevented a detailed examination of internal in vivo or in vitro airflow patterns. To gain more insight into the flow pattern in inaccessible regions of the nasal cavity we have conducted a mathematical simulation of asymmetric airflow patterns through the nose. Development of a nose-like model, which resembles the complex structure of the nasal cavity, has allowed for a detailed analysis of various boundary conditions and structural parameters. The coronal and sagittal cross-sections of the cavity were modeled as trapezoids. The inferior and middle turbinates were represented by curved plates that emerge from the lateral walls. The airflow was considered to be incompressible, steady and laminar. Numerical computations show that the main air flux is along the cavity floor, while the turbinate structures direct the flow in an anterior-posterior direction. The presence of the turbinates and the trapezoidal shape of the cavity force more air flux towards the olfactory organs at the top of the cavity.

Humans↗
PubMed1993

Dynamic model of the bronchial tree.

We present a distributed model of the bronchial tree which simulates the global dynamic characteristics of the lung. Local mechanical characteristics of each airway are represented by RCL circuits and parameters of the electrical components are determined from local physiological data. The bronchi geometry is described by Weibel's symmetric model, the flow in each airway is assumed laminar and mixing effects at the bifurcations are neglected; the transpulmonary pressure is assumed to be sinusoidal. In simulations of quiet breathing the resistance to airflow is found to be dominant, the flow amplitude decreasing as breathing frequency increases, but remaining almost constant in all the generations. Simulations of ventilation through obstructed lungs show frequency dependence of the dynamic characteristics in very compliant lungs. The global resistance to airflow and the dynamic compliance of the bronchi decrease as the forced oscillation frequency increases in a pattern similar to in vivo measurements in diseased lungs. This may be an outcome of the RCL properties of the network rather than due to uneven distribution of mechanical properties of the lung.

Biomechanical Phenomena↗
PubMed1993

Construction and uses of a concentric catheter for gas sampling in lung airways.

A catheter for intra-airway sampling of gas concentrations was constructed from concentric polyethylene tubes. The internal tube (0.58 mm ID, 0.91 mm OD) was connected to a gas analyzer while the external tube (1.20 mm ID, 1.75 mm OD) was constantly flushed by air or a calibration gas, except during sampling. Injection and sampling dead spaces were 0.35 and 0.28 ml, respectively. Delay at 4-ml/min sampling rate was 4.0 +/- 0.2 s. The 0-90% step response to a sudden change in gas composition was 0.24 s when connected to a mass spectrometer. This catheter was used to assess tracer gas dispersion during oscillatory flow (1-20 Hz) in a straight long tube. Local concentrations measured through the catheter, after a small bolus of tracer gas was injected through the external tube, compared favorably with direct measurements through needles inserted via the tube wall and with theoretical predictions. The catheter was also used to measure intra-airway gas concentrations in dog airways during spontaneous breathing, conventional mechanical ventilation, high-frequency ventilation, high-frequency vibration ventilation, and constant-flow ventilation. It ws placed by a fiber-optic bronchoscope and used to measure local quasi-steady concentrations of CO2 and local dispersion with the bolus method. The occurrence of catheter clogging with secretions was substantially reduced with flow through the external tube. Transmitting a calibration gas through the external tube facilitated in situ recalibration of the gas analyzer without removing the catheter. The use of this catheter improved the efficiency and accuracy of measurements of gas concentrations inside lung airways.

Animals↗
PubMed1992

Steady flow through collapsible tubes: measurements of flow and geometry.

Compliant tubes attain a complex three-dimensional geometry when the external pressure exceeds the internal pressure and the tube is partially collapsed. A new technique for remote measurement of dynamic surfaces was applied to classical experiments with collapsible tubes. This work presents measurements of the three-dimensional structure of the tube as well as pressure and flow measurements during static loading and during steady-state fluid flow. Results are shown for two tubes of the same material and internal diameter but with different wall thicknesses. The measured tube laws compare well with previously published data and suggest the possible existence of a similarity tube law. The steady flow measurements did not compare well with the one-dimensional theoretical predictions.

Compliance↗
PubMed1992

Gas dispersion in volume-cycled tube flow. I. Theory.

A mathematical theory is derived for the dispersion of a contaminant bolus introduced into a fully developed volume-cycled oscillatory pipe flow. The convection-diffusion equation is solved for a tracer gas bolus by expressing the local concentration field as a series expansion of derivatives of the area-averaged concentration. The local, as well as the area-averaged, concentration is determined for a uniform initial slug or Gaussian bolus. The effect of various flow parameters such as Womersley parameter, Schmidt number, and tidal volume is investigated. The overall dispersion is characterized by a time-averaged effective diffusion coefficient, which for long duration coincides with previous dispersion theories based on a constant linear axial concentration profile. The effective diffusion coefficient can be determined from the local time history of concentration, independent of the spatial location or the initial tracer bolus. Furthermore the local peaks of the concentration-time curve follow a decaying curve dictated by the time-averaged effective diffusion coefficient. Thus the theory is directly applicable for dispersion measurements in oscillatory tube flows, a basis for the pulmonary airways application, as shown by Gaver et al. (J. Appl. Physiol. 72: 321-331, 1992).

Bronchi↗
PubMed1992

Gas dispersion in volume-cycled tube flow. II. Tracer bolus experiments.

We present a new method for rapid measurement of local gas dispersion in volume-cycled tube flow. After a small bolus of tracer gas (argon) was injected into the oscillating flow, the time-averaged effective diffusion coefficient (mean value of Deff/D) for axial transport of a tracer gas is evaluated from local argon concentration measurements taken by a mass spectrometer. Two methods are presented for the evaluation of mean value of Deff/D from the concentration measurements: one uses all the sampled data, and the other uses only the local peaks of the concentration. Experiments were conducted in two tubes (radius = 0.85 or 1.0 cm) over a range of frequencies (0.42 less than or equal to f less than or equal to 8.5 Hz) and tidal volumes (7 less than or equal to VT less than or equal to 48 ml). The experimental results show very good agreement with the theoretical predictions of Elad et al. (J. Appl. Physiol. 72: 312-320, 1992). In the absence of oscillations (static fluid), the resulting mean value of Deff/D converges to that of molecular diffusion. We also show that concentration data may be acquired at any radial or axial position, not necessarily at the tracer gas injection point, and the resulting mean value of Deff/D is independent of the spatial position of the sampling catheter. This method is of similar accuracy and is substantially faster than previous methods for measuring gas dispersion in oscillatory flows. The rapidity of these measurements may permit this method to be used for the in vivo assessment of gas transport properties within the pulmonary system.

Argon↗
PubMed1991

Eumycetoma caused by Curvularia lunata in a dog.

Curvularia lunata was cultured from black granules found in granulomatous tumefactions excised from the subcutis of a three year old Medium Schnauzer dog. Draining sinuses were present in some of the tumefactions. Accordingly the diagnosis of eumycotic mycetoma was made. This diagnosis was confirmed by histopathological examination. During the four years following the first surgical intervention, several more similar tumefactions were excised on three different occasions. The dog died of chronic renal failure at the age of 8 years. There was no bone involvement or visceral diffusion of the fungus. The granules were examined by scanning electron microscopy. Immunoglobulins in the dog's serum, assessed by a qualitative test, proved to be equal to immunoglobulins in the serum of a control dog. Precipitating antibodies against C. lunata were not found. The dog was treated for 150 days with itraconazole. In spite of good initial results, recurrence of the fungal lesions were observed after the treatment's interruption. Further treatment with itraconazole for 45 days proved ineffective. No side effects of the drug were observed. This is, to the best of our knowledge, the first case in which C. lunata is identified as the causative agent of an animal eumycetoma.

Animals↗