Survival of microbial films in the microwave oven.

Air-dried films of Escherichia coli, Saccharomyces cerevisiae, and Bacillus subtilis spores on membrane filters, exposed to 10 min full power (650 W, 2450 MHz) irradiation in a Toshiba model ER776BT microwave oven, showed a 5-, 2-, and 0-log reduction of viable organisms respectively. Suspensions of cells or spores in phosphate buffer treated under similar conditions showed 8 logs of killing within 30 s (S. cerevisiae), 45 s(E. coli), and by 10 min (B. subtilis spores) of exposure.     

Decalcification of teeth in a microwave oven

Summary The effects of microwave radiation in reducing decalcification time were evaluated by measuring rates of calcium removal from samples of rat and cat teeth in 0.1 mol l^–1 EDTA. In some cases, 3% glutaraldehyde was added to the decalcifying solution. Test specimens were placed in a microwave oven at 39±2°C for repeated periods of 1–2h. Control specimens were placed in a coventional oven at 39°C for the same times or held at room temperature. The calcium removed during each treatment was measured using an atomic absorption spectrophotometer. There was no consistent difference between the results obtained with microwave radiation as compared with heating in a conventional oven, although in both cases decalcification was slightly faster than at room temperature. These results are attributed to thermal effects. No evidence for non-thermal effects of micro-radiation was found.     

Phytoseiid mite populations on dormant grapevines: extraction using a microwave oven

A microwave oven technique for monitoring overwintering phytoseiid mite populations on dormant grapevines was developed. The removal and recovery of mites from grapevine wood material is based on excitation of mites in a microwave oven so that they fall to the bottom of a plastic bag. Contents of the bag are subsequently examined under a stereomicroscope.     

The microwave oven: a novel means of decontaminating parasitological specimens and glassware

This study was conducted to determine the effects of microwave radiation on developmental and infective stages of Eimeria nieschulzi, Strongyloides ratti, and Taenia taeniaeformis. Fecal samples and laboratory preparations containing these three parasites were subjected to microwave radiation for brief periods in a microwave oven, and then in vitro and/or in vivo assessments of viability were made for each organism and preparation. Our results showed that microwave irradiation is extremely effective in killing or preventing development of helminth and protozoan parasites without unduly distorting eggs or developmental stages. Therefore, microwaves may prove useful for decontaminating diagnostic samples or sterilizing contaminated materials in the laboratory and thus for reducing risk to laboratory personnel from parasites of public health importance.     

Sterilization of culture media for orchids using a microwave oven

Production of orchid seedlings often requires complex laboratory infrastructure; therefore, a simple and low-cost method would be of general benefit to many small-scale producers and orchid enthusiasts. This article describes a protocol for preparing culture media using a domestic microwave oven. Two alternative culture media were evaluated for a range of factors, including the duration of boiling, the efficacy of antiseptics applied to jars and media, the concentration of the antiseptic hydrogen peroxide required for sterilization, and the growth of Oncidium cebolleta and Phalaenopsis amabilis plantlets in media prepared using a microwave oven compared with conventionally autoclaved media. It was found that addition of 2 mL of 30% hydrogen peroxide (Peridrol® solution) per liter of culture medium, an 8-min boiling time in the microwave oven, and 8 g/L agar were sufficient to produce solidified culture media, which facilitated orchard seed germination and growth without contamination. Furthermore, the microwaved media exhibited superior plantlet growth to autoclaved media.     

Cook/chill foodservice system with a microwave oven: Injured aerobic bacteria during food product flow

Summary This study determined how processing in cook/chill foodservice systems affected the quantity of sublethally injured bacteria in food. Beef loaf and frozen green beans were each prepared three times in a laboratory simulation following time-temperature recommendations of the Hazard Analysis Critical Control Point model. Beef loaf (15 kg) was initially cooked (1 kg/loaf) to a mean and temperature of 66°C; stored 24 h at 6°C and sliced, 100 g/poriton. Beans (4.5 kg) were removed from the freezer, stored 24 h at 6°C, and portioned, 100 g/ portion. Portions were helds at 6°C for 2 h and then were microwave-heated individually for 20, 50, 80, or 110s. Samples were then plated using Plate Count Agar (PCA) to obtain aerobic plate count (APC) and PAC plus 3.0% (beans) or 4.5% (beaf loaf) sodium chloride. The difference in results between the two counts (APC less PCA + NaCl) was defined as a measure of sublethally injured bacteria in the sample. The proportion of injured cells in beef loaf before microwave-heating was larger than that in green beans before microwave-heating probably because the beef loaf was initially cooked. Lenghtening the time of microwave-heating increased the proportion of injured cells in all microwave treatments of beef loaf and also in green beans when the time was 50 or more seconds. Research supported by the College of Agricultural and Life Sciences, University of Wisconsin-Madison     

Ivermectin: an update

Ivermecan was introduced as an antiparasitic agent in 1981. It is now registered for animal-health use in 35 countries and is being evaluated for possible use in man. This review summarises its antiparasitic efficacy and apparent mode of action. Additional information is given in previous review articles.     

Yersinia: an update

The 8th International Symposium on Yersinia was held in Turku, Finland, 4–8 September 2002.     

Clonorchiasis: an update

Clonorchis sinensis, the Chinese or oriental liver fluke, is an important human parasite and is widely distributed in southern Korea, China (including Taiwan), Japan, northern Vietnam and the far eastern part of Russia. Clonorchiasis occurs in all parts of the world where there are Asian immigrants from endemic areas. The human and animal reservoir hosts (dogs, pigs, cats and rats) acquire the infection from the ingestion of raw fish containing infectious metacercariae. The first intermediate snail hosts are mainly species of Parafossarulus and Bithynia. Numerous species of freshwater fish serve as the second intermediate hosts of C. sinensis. Extensive studies of clonorchiasis during several decades in Japan, Korea, China and other countries have shown much progress in proving its morphological features including ultrastructure, biology, pathogenesis, epidemiology, clinical manifestations and chemotherapy. The present review deals with mainly current results obtained on the epidemiological, pathological and clinical aspects, as well as control measures in endemic areas. As for the complications of clonorchiasis, formation of calculi in the intrahepatic biliary passages is one of the most characteristic pathological features. It is sometimes accompanied by suppurative cholangitis, cholecystitis, cholangiohepatitis and ultimately can cause cholangiocarcinoma. Experimental results on the relationship to the occurrence of cholangiocarcinoma are presented. Clinical diagnosis by radiological findings including cholangiography, sonography and computerized tomography as well as magnetic resonance imaging for biliary or pancreatic ducts are outlined. Current studies on immunology and molecular biology of C. sinensis were introduced. Praziquantel is the drug of choice for clonorchiasis. The most effective regimen is 25 mg kg(-1) three times daily (total dose, 75 mg kg(-1)) administered orally at 5- to 6-h intervals over a single day. Prevention and control measures are also discussed.     

A practical approach to routine immunostaining of paraffin sections in the microwave oven

Summary The Streptavidin-Biotin Complex (SABC) Immunostaining method can be carried out by performing the rinsing and blocking steps and in addition the incubations with the primary and the secondary antibody sera in the microwave oven. Irradiation of the Streptavidin-Biotin Complex reduces stain activity due to destruction of horseradish peroxidase (HRP) (Boon & Kok, 1988). Therefore, we decided not to perform this step in the microwave oven. The microwave incubations can be performed using antisera dilutions of 1:1000 (instead of 1:50) in tissue fixed with Kryofix, allowing staining in staining racks. This keeps hands-on time low and simplifies the microwave steps. It is very difficult to obtain reproducible results in the microwave oven using droplet incubations due to problems with hot spots and antenna effects. These problems are avoided when cuvettes are used and air is blown through the solutions during microwave incubations. With effective temperature control the method is highly reproducible, and takes at least 100 min less than the conventional SABC method. It is, in particular, attractive when large series of slides must be routinely immunostained and when reproducible results are desired.     

Organ temperature measurement in a microwave oven by resonance frequency shift

An experimental system has been developed that can indirectly measure temperature in a high-intensity microwave field over a broad range of conditions. A RF amplifier connected closed-loop around a high Q cavity oscillates at one of the natural modes of the oven. A bandpass filter selects the mode of interest. As the frozen sample is thawed, an increase in dielectric constant occurs, decreasing the resonance frequency of the cavity. Calibration of the system is performed by measuring the frequency shift for samples whose temperatures are known, Rotation of samples during thawing often causes oscillations of the resonance frequency. These oscillations are generated by asymmetric sample properties and geometry, and hot spots developed during the thaw. Development of a method that would predict hot spot location from these resonance frequency oscillations and permit modulation of the magnetron or sample rotation to minimize thermal runaway is suggested.     

Vaccination of the elderly: an update

Vaccination of the elderly still requires attention. The vaccination coverage for tetanus, influenza and pneumococcal infections is merely 40, 60 and 30%, respectively. Besides a reduction in mortality (67%) and a reduction of hospitalisation for pneumonia and influenza (50%), vaccination against influenza also results in a decrease in cardio- and cerebrovascular morbidity (20%) as well as in a decrease in the frequency of doctor visits for respiratory infections for COPD patients. Vaccination of children and health care personnel can further reduce transmission of influenza and subsequent influenza related complications in the elderly. Pneumococcal invasive disease can be reduced by 50% through vaccination. Vaccination of children with the conjugate vaccine can further reduce the incidence of pneumococcal invasive disease in the elderly. Further improvements in vaccine coverage levels are needed, mainly among elderly persons, children and persons at increased risk.     

Kinesins in the spindle: an update

Eukaryotes contain a superfamily of microtubule-based motor proteins comprising kinesin and a number of related proteins that are thought to participate in various forms of intracellular motility, including cell division and organelle transport. The role of various members of the kinesin superfamily in chromosome segregation and spindle morphogenesis was described in TCB last year in parts of a series on cytoplasmic motor proteins. In this brief update, Helen Epstein and Jon Scholey comment on new findings that have improved our understanding of the functions of kinesin-related proteins in mitosis and meiosis.