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Biomedical subjects

I Glazer

Publications and source records attributed to I Glazer.

At least 37 records · Page 2Linked to original sources
PubMed1999

Interaction between ticks (Acari: Ixodidae) and pathogenic nematodes (Nematoda): susceptibility of tick species at various developmental stages.

The virulence of entomopathogenic nematodes (Steinernematidae and Heterorhabditidae) to tick species under laboratory conditions is reported. The susceptibility of larval, nymphal, and adult stages of the ticks Hyalomma excavatum (Koch), Rhipicephalus bursa (Canestrini & Fanz), and R. sanguineus (Latereille) to 2 strains of Steinernema carpocapsae and 3 strains of Heterorhabditis bacteriophora were compared in laboratory assays. Preimaginal stages of ticks were found to be more resistant to the nematodes than were adult ticks which exhibited 80-100% mortality in a dish containing 5,000 infective juveniles of H. bacteriophora IS-3 or IS-5 strains isolated in Israel. These 2 strains were found to be much more virulent to unfed adult ticks than were the other isolates. No marked difference was found between engorged ticks and unfed adults of R. sanguineus or H. excavatum in terms of mortality, whereas engorged males and unfed females of R. bursa were significantly more susceptible than unfed males or engorged females.

Animals↗
PubMed1998

Entomopathogenic nematodes as a potential biological control method for ticks.

Entomopathogenic nematodes have been used for biological control of certain insect pests. In these studies the nematodes were tested as a possible biological control agent for engorged female ticks. Five species of infective juveniles (IJs) were tested initially for their ability to penetrate and kill ticks, including Steinernema glaseri (SG), S. riobravus (SR), S. carpocapsae (DT), S. feltiae (SF) and Heterorhabiditis bacteriophora (HP88). Infective juveniles (IJs) of SRs and SFs appeared to be the most effective in killing ticks and invaded and killed 30 to 100% of replete females. These two nematode species were tested on several tick species including Amblyomma americanum, A. cajennense, A. maculatum, Dermacentor variabilis and Rhipicephalus sanguineus. Although the killing rate of each tick species varied, the nematodes did not appear to be host specific and were able to kill ticks of all species tested. Egg mass weights of exposed ticks of each species were significantly lower than those of the controls. Ticks were examined with microscopy to determine whether nematodes entered and multiplied inside ticks. Partially fed female Amblyomma americanum and Dermacentor variabilis exposed to 5000 IJs in petri dishes were collected at 8, 24, 48 and 96 hrs (Trial 1) and 1, 2, 3, 4, 7 and 9 days (Trial 2) post-exposure, and fixed, processed and embedded in resin for microscopy studies. Only a few nematodes were seen in the hemocoel and tissues and they were surrounded by a clear space. Bacteria, released from the nematodes, were present in the exposed ticks and appeared to increase daily causing a generalized infection. Degeneration of tick tissues and death of the ticks appeared to result from bacterial proliferation. Nematodes did not multiply within ticks as they do in insect larvae. In these controlled laboratory studies, exposure of ticks to nematodes resulted in tick mortality and reduced egg production. Entomopathogenic nematodes appear to have potential as a biological control agent of ticks, but future studies will be required to determine whether nematode/tick interactions will occur in the field.

Animals↗
PubMed1998

Thermal response of Heterorhabditis bacteriophora transformed with the Caenorhabditis elegans hsp70 encoding gene.

A heat-shock response is induced when cells are exposed to temperatures slightly higher than their optimal physiological temperature. This response is based on the synthesis of heat-shock proteins encoded by the heat-shock genes. A correlation between the increased thermotolerance and production of 70-kDa heat-shock protein (hsp70) has been observed in many organisms. We tested this hypothesis by transferring a Caenorhabditis elegans heat-inducible hsp70 A-encoding gene into the entomopathogenic nematodes Heterorhabditis bacteriophora Hp88. Successful transformation of the gene was confirmed by Southern blot hybridization and polymerase chain reaction. Our blot studies showed that the transgenic nematodes contained five to ten copies per genome of the introduced hsp70 A gene. hsp70 mRNA transcripts were detected in both wild-type and transgenic nematodes. Transcripts increased severalfold in transgenic nematodes upon heat shock. Infective juveniles of both transgenic and wild-type nematodes that exposed to a sublethal heat treatment (35 degrees C) for 2 h followed by a normally lethal heat treatment (40 degrees C) for 1 h. More than 90% of transgenic nematodes survived heat treatment, compared to 2% to 3% of the wild-type strain. Our observations establish that overexpression of hsp70 A gene resulted an enhanced thermotolerance in the transgenic nematodes. The transgenic nematodes displayed normal growth and development.

Animals↗
PubMed1998

Interaction of entomopathogenic nematodes (Steinernematidae) with selected species of ixodid ticks (Acari: Ixodidae).

Entomopathogenic nematodes, currently used for biological control of various insect pests, were tested for their ability to penetrate and kill replete females of several species of ticks including Dermacentor variabilis (Say), Rhipicephalus sanguineus (Latreille), Amblyomma maculatum Koch, and A. cajennense (F.). These species were found to be susceptible to the entomopathogenic nematodes, Steinernema feltiae (Filipjev) or S. riobravus (Cabanillas & Poinar), shown in previous studies in our laboratory to be attracted to and kill replete A. americanum. S. riobravus killed D. variabilis (96%), R. sanguineus (89%), A. maculatum (24%), and A. cajennense (88%), and S. feltiae killed D. variabilis (91%) and R. sanguineus (71%). Of the ticks that survived mean egg mass weights were significantly lower than those of the unexposed controls. When nematode-exposed ticks were examined with light microscopy, nematodes were found to have entered ticks but did not multiply or produce subsequent generations of infective juveniles. The nematodes were separated from surrounding tissues by a clear space, suggesting that they produced protective compounds. Bacteria, thought to be symbiotes released from the nematodes, multiplied initially in the hemocoel of the tick and subsequently were found throughout the degenerating tick tissues. These bacteria eventually filled the tick and appeared to be the cause of tick death. Nematode guts were filled with the bacteria, suggesting that the bacteria were a food source. When ticks were exposed to nematodes while feeding on cattle, partially engorged females were most susceptible to the nematodes. Tick mortality and reduced egg production resulted when the ticks had fed 6 and 9 d before nematode exposure but not when ticks were exposed after 3 d of feeding. Exposure of feeding female ticks demonstrated that the nematodes were able to penetrate tick orifices other than via the hypostome, which was embedded in the bovine epidermis for the duration of the feeding process.

Animals↗
PubMed1997

Migratory behaviour and desiccation tolerance of protostrongylid nematode first-stage larvae.

Migration of first-stage larvae (L1) from faeces to soil is a crucial stage in the life-history of protostrongylids transmitted via land snails. Migration of Muellerius cf. capillaris and a Cystocaulus sp. L1 from fresh Nubian ibex (Capra ibex nubiana) faeces (48-50% water content, W.C.) to substrate soils (at 100% r.h., 26 degrees C) was measured experimentally using dry (3 +/- 1% W.C.), wet (31 +/- 0.43% W.C.) and flooded (48.4 +/- 2.45% W.C.) soils. The highest migration rates (90.4 +/- 1.6% migration) in both species occurred on flooded soils when the faecal pellet W.C. reached 90%. The next highest migration rates (43.2 +/- 3.6% migration, at 60% faecal W.C.) were on the wet soils and no migration occurred on dry soil or dry-substrate papers. Migration rates did not differ significantly (P > 0.05) between species. Active Theba pisana were not infected by M. cf. capillaris L1 on dry infested soils, but were infected following rehydration of the same soils. By day 10, L1 of M. cf. capillaris demonstrated lower survival rates in water and in 97% and 76% r.h. (74.5%, 15.2% and 1.9%, respectively) than the Cystocaulus sp. (97.5%, 43.8%, 43.3%) and Protostrongylus sp. (97.9%, 43.2%, 23.8%, P < 0.05). All three nematodes had a remarkably high survival rate (> 99% overall survival, by day 10) when exposed directly to 0% r.h. at 23 degrees C. Results demonstrate the ability of L1 to survive extreme desiccation through anhydrobiosis. Migration of L1 from faeces to soil can take place only during rains which coincide with peak activity of land snails in desert habitat.

Animals↗
PubMed1997

Effects of infected insects on secondary invasion of steinernematid entomopathogenic nematodes.

Factors affecting 'invasion efficiency' of steinernematid entomopathogenic nematodes into hosts were elucidated. The phenomenon that only part (10-40%) of the nematode population invades the target host has been recorded in many studies. It has been mainly ascribed to differences in the ability of individual nematodes to infect. In the present study the effect of an infected host, the wax moth Galleria mellonella, on subsequent infection of the entomopathogenic nematodes Steinernema carpocapsae Mexican, S. riobravus and S. feltiae was evaluated. The invasion rate of the 3 nematode species to a non-infected host was reduced by 40-60% after pre-exposure to infected hosts. These nematodes regained their full invasion potential after they were rinsed with water. Invasion into insects which were previously injected with nematodes was significantly reduced by 60-80% 6-9 h after injection. The reduction in subsequent invasion due to the initial infection was nematode species specific. This phenomenon was also observed with other lepidopteran pests (Helicoverpa armigera and Spodoptera littoralis). The data indicate that the initial infection by entomopathogenic nematodes induced the release of a substance which reduced the subsequent invasion. The chemical and biological characteristics of this substance are currently under investigation.

Animals↗
PubMed1992

Infectivity of entomopathogenic nematodes (Steinernematidae and Heterorhabditidae) to female ticks of Boophilus annulatus (Arachnida: Ixodidae).

Exposing Boophilus annulatus (Say) to different concentrations of Steinernema carpocapsae (Filipjev) infective juveniles in petri dishes (50-10,000 nematodes per dish) resulted in high mortality (greater than 90%) at nematode concentrations as low as 500 nematodes per dish within 8 d. At a concentration of 10,000 nematodes per dish, 100% of the ticks died within 2 d after infestation. After exposure to 500 nematodes per dish, complete mortality was achieved with the Heterorhabditis bacteriophora strain 'HP88' within 4 d. During the same period, only 15 and 40% mortality were recorded with the 'Mexican' and 'All' strains of S. carpocapsae, respectively. In a lethal dose analysis, S. carpocapsae strain 'DT' was the most infective strain with the lowest LD50 and LD90 values (15 and 165 infective juveniles per tick, respectively). The 'All' strain of S. carpocapsae was the least infective of the four strains tested, with LD50 and LD90 values of 372 and 9,251 infective juveniles/tick, respectively. Optimal temperature for tick control by the nematodes was between 22 and 26 degrees C. Mortality rate was reduced at 18 and 30 degrees C. The susceptibility of fully engorged ticks was not influenced by the weight of the replete females. Nematode infection did not have an adverse effect on egg laying by surviving ticks.

Animals↗
PubMed1987

An improved comprehensive medical kit for passenger aircraft.

For the past 20 years, El Al has been carrying drugs and equipment for use by physicians on board the aircraft for medical emergencies. In addition, first aid equipment including a resuscitator (respirator)--to be used by the trained cabin attendants--and over-the-counter medications in a Hostess Purse are also carried. We have recently adopted a standard medical kit (MK) which contains primarily drugs considered essential to emergency cardiac care. However, its contents were extended, based on our experience in the airline and the recommendations of the Air Transport Medicine Committee of the Aerospace Medical Association. This would enable a competent physician on board to reasonably manage most medical emergencies until landing at the scheduled destination or at the nearest safe airport where better diagnostic means and treatment may be available. Equipment and drugs are designed to handle most acute allergic, cardiac, respiratory, gastrointestinal, renal, nervous, and psychiatric emergencies. Also included in the MK is a table of the drugs, their trade name, generic name, action, indications, contraindications, administration, and dosage. A check-off list of the drugs and equipment used by the physician, as well as space for provisional diagnosis and disposition, is provided.

Aircraft↗
PubMed1981

Antibodies to inhalant fungal antigens in patients with asthma in Israel.

Thirty-eight of 97 asthmatic patients, seven of 26 normal subjects and two of 39 patients with chronic obstructive pulmonary disease (COPD) were found to have antibodies to one or more of the inhalant fungi and candida antigens assayed by both immunodiffusion and counterimmune electrophoresis. Atopy was demonstrated in 33 of the 38 asthmatic patients with antibodies. Eleven asthmatics had anti-alternaria antibodies while only two reacted to aspergillus.

Alternaria↗