Inactivation of Cryptosporidium parvum oocysts in fresh apple cider by UV irradiation.

This study evaluated the efficacy of UV irradiation on the inactivation of Cryptosporidium parvum oocysts in fresh apple cider. Cider was inoculated with oocysts and exposed to 14.32 mJ of UV irradiation/cm(2). Oocyst viability was assessed with the gamma interferon gene knockout (GKO) mouse and infant BALB/cByJ mouse models. All GKO mice challenged with UV-treated cider demonstrated no morbidity or mortality, and infant BALB/c mice challenged with treated cider were negative for the presence of C. parvum. In contrast, the GKO mice challenged with non-UV-treated inoculated cider died and the parasite was detected in the ileums of all challenged infant mice. This study shows that UV irradiation can be used to inactivate C. parvum in fresh apple cider.

Differences in optic discs in low-tension glaucoma patients with relatively low or high pressures.

We evaluated the differences in the optic nerve head in patients with chronic open-angle glaucoma (HTG) and those with low-tension glaucoma with either relatively high (between 16 and 21 mmHg [LTGH]) or low (< or = 15 mmHg [LTGL]) intraocular pressures. We included 36 patients in this study. We found that LTGL patients had a significantly greater mean area of peripapillary atrophy inferior to the optic disc (0.65 +/- 0.38 mm2) than LTGH (0.40 +/- 0.38 mm2) or HTG (0.34 +/- 0.25 mm2) patients (p < 0.005). No significant difference was found between groups for the area of the neural rim, optic disc, cup/pallor discrepancy, or peripapillary halo, or in the diameter of the largest artery or vein in the inferior and superior peripapillary area. This study raises the question of whether a separate mechanism of damage could exist at the optic disc in patients whose intraocular pressure is < or = 15 mmHg because of a greater extent of peripapillary atrophy than in patients with higher intraocular pressures.

Effect of pasteurization on infectivity of Cryptosporidium parvum oocysts in water and milk.

Cryptosporidium parvum is a major cause of diarrheal disease in humans and has been identified in 78 other species of mammals. The oocyst stage, excreted in feces of infected humans and animals, has been responsible for recent waterborne outbreaks of human cryptosporidiosis. High temperature and long exposure time have been shown to render oocysts (suspended in water) noninfectious, but for practical purposes, it is important to know if high-temperature--short-time conditions (71.7 degrees C for 15 s) used in commercial pasteurization are sufficient to destroy infectivity of oocysts. In this study, oocysts were suspended in either water or whole milk and heated to 71.7 degrees C for 15, 10, or 5 s in a laboratory-scale pasteurizer. Pasteurized and nonpasteurized (control) oocysts were then tested for the ability to infect infant mice. No mice (0 of 177) given 10(5) oocysts pasteurized for 15, 10, or 5 s in either water or milk were found to be infected with C. parvum on the basis of histologic examination of the terminal ileum. In contrast, all (80 of 80) control mice given nonpasteurized oocysts were heavily infected. These data indicate that high-temperature--short-time pasteurization is sufficient to destroy the infectivity of C. parvum oocysts in water and milk.

Effect of fucoidan during activation of human plasminogen.

Fucoidan [sulfated poly (L-fucopyranose)] was compared with 6-aminohexanoic acid (6-AH) or CNBr-cleaved fibrinogen (CNBr-Fbg) alone or in combination in enhancing the activation of glutamic plasminogen (Glu-Plg) or lysine plasminogen (Lys-Plg) by two-chain tissue plasminogen activator (t-PA) or LMwt-urokinase or by streptokinase. Fucoidan enhanced the t-PA activation of Glu-Plg or Lys-Plg at Plg concentrations greater than 75nM, while stimulation by CNBr-Fbg of t-PA activation followed saturation kinetics of Michaelis-Menton. During t-PA activation of Glu-Plg, a high degree of synergism was observed between 6-AH and fucoidan while the enhancement by CNBr-Fbg was not influenced by fucoidan and was reversed by 6-AH. Fucoidan alone at higher concentrations was effective in enhancing the activation of Glu-Plg by urokinase while the combination of fucoidan and 6-AH showed additive effect in enhancing the activation of Lys-Plg. The activation of Glu-Plg by streptokinase was reversed by fucoidan in a manner similar to that reported for 6-AH. The results are interpreted to suggest that CNBr-Fbg and 6-AH compete with each other for the same lysine binding sites (LBS) on the Plg molecule while fucoidan acted synergistically with 6-AH in enhancing the t-PA activation of Glu-Plg by a different mechanism. The double reciprocal plot for the interaction of Glu-Plg and urokinase also showed a significantly higher affinity between the two in presence of fucoidan.

Reproducibility of the Glaucoma-scope in cadaver eyes.

We evaluated the intra- and inter-observer variability of depth measurements of the optic disc in cadaver eyes using the Glaucoma-scope. Intra-observer variation of 10 separately captured images became significantly greater with increasing depth of the optic cup (p < 0.001). The standard deviation of depth measurements were 9.06 mu over the neural rim, 25.00 mu along the cup wall, and 40.94 mu at the bottom of the optic cup. However, intra-observer variation of a single captured image did not increase with greater optic cup depth. Intra-observer variation, but not inter-observer variation, generally was greater when measuring the superior than inferior optic disc (p < 0.05). This study suggests that when capturing separate optic disc images with the Glaucoma-scope, increased variation in depth measurements can be expected with greater optic cup depth and in the superior portion of the optic disc.

Role of vitamin D in the pathogenesis and treatment of osteoporosis.

Alterations in vitamin D metabolism normally occur after the menopause and with aging. Increases in skeletal remodeling as a consequence of estrogen deficiency lead to increased bone resorption, suppression of serum 1,25-dihydroxy-vitamin D and intestinal absorption of calcium and increases in urinary calcium. Age-related changes in vitamin D metabolism include diminished dermal production of 7-dehydrocholesterol, the precursor of previtamin D(3), vitamin D deficiency as a consequence of inadequate intake or exposure to sunshine (individuals may be institutionalized or housebound), a decline in intestinal vitamin D receptors and diminished intestinal absorption of calcium and secondary hyperparathyroidism which leads to further bone loss. These changes also have been implicated in the pathogenesis of senile osteoporosis. Treatment with vitamin D and its analogues such as 1,25-dihydrox-yvitamin D(3 )is sometimes of value in preventing bone loss and fractures in patients with postmenopausal osteoporosis and senile osteoporosis. However, the drugs have not been approved for treatment and prevention of osteoporosis.

Testing for food-borne parasites, their metabolic products and symbionts.

Microscopic animals associated with foods include free-living and saprophytic invertebrates, parasites of hosts other than humans, and parasitic animals specifically designated as food-borne that can infect a human host by the gastrointestinal route. The first general method used to screen for food-borne species was digestion with pepsin and hydrochloric acid at 36 degrees C, based on the "artificial stomach juice" technique for recovering larvae of the nematode Trichinella spiralis from muscle. This method selects for forms capable of surviving a mammalian digestive enzyme at mammalian temperatures. It has been used successfully to recover a variety of food-borne helminths, not only from mammalian flesh but also from fish, shellfish and molluscs, and can be adapted to greatly reduce the "background of living animals" associated with soils and the crops grown in them. However, not all animal forms that survive digestion are food-borne parasites, and all that succumb are not necessarily noninfectious. Methodology to test for food-borne parasites is, in general, not as efficient as that for food-borne bacteria. Recent developments in food parasitology indicate a need to identify not only the parasite, but also its metabolic products and associated symbionts.

Principles and costs in the regulation of microbially contaminated foods.

A strong code of regulations exists in the United States to control pathogens and other microbes in food and drink. Despite strict enforcement, food-borne illness persists. Parasitic animals in foods are particularly difficult to detect because there are no simple culture systems for their multiplication and because sanitary measures against fecal contamination are ineffective against parasite species transmitted by other routes. To attain a high degree of safety, total processing of foods by heat- and/or irradiation-pasteurization combined with sterile packaging may be required. The cost of regulating food-borne microbes, while large, is probably surpassed by the cost of food-borne illness (estimated to be US$50 billion annually), resulting in net savings.

Public health and research perspectives on the microbial contamination of foods.

Scientific advances in methodology and epidemiology have resulted in a renewed awareness of foodborne disease, and increased contact among nations of the world has stimulated rapid global distribution of foods as well as foodborne pathogens. New food vehicles are being identified for old, familiar pathogens, and new pathogens are being discovered. Current research in food microbiology has spurred development of rapid and specific methods to identify these pathogens and to assess their virulence. Organisms of recent interest, such as Bacillus, Yersinia, Campylobacter, Listeria, Sporothrix, Giardia, Cryptosporidium, and Anisakis, are the foci of new investigations, as are the more familiar foodborne pathogens, Salmonella, Shigella, Clostridium, Staphylococcus, Entamoeba and Ascaris. Some foodborne organisms, such as parasitic protozoa, serve as hosts for unique bacterial and viral symbionts but also might become infected with mammalian viruses. The remote possibility of the transmission of human immunodeficiency viruses in foodborne protozoa is discussed.

Bronchiolitis obliterans organising pneumonia in a patient with ulcerative colitis.

A young woman with ulcerative colitis developed pneumonia, which responded to corticosteroids. Histological examination showed this to be bronchiolitis obliterans organising pneumonia.

Immunoassays in therapeutic drug monitoring.

Numerous immunoassay methods are now in routine use for therapeutic drug monitoring of drugs and metabolites. Most methods are homogeneous immunoassays with excellent specificity, accuracy, and precision. In addition, these assays are readily automated, and commercial versions of theses reagents are available with dedicated instrumentation. This report reviews current methods and systems and discusses methodology that has been developed for physician office or other nontraditional settings.

Survey of fresh vegetables for nematodes, amoebae, and Salmonella.

Contamination by nematodes, amoebae, and bacteria of the genus Salmonella was estimated in a 2-year survey of salad vegetables obtained from wholesale and retail sources. The vegetables examined were cucumbers, cabbage, lettuce, celery, carrots, radishes, tomatoes, mushrooms, cauliflower, and spinach. Nematode eggs and larvae were recovered by the Nacconol-ether centrifugation method. Some nematode eggs were identified as parasitic Ascaris sp.; the majority of larval nematodes were thought to be soil-dwelling species. Amoebae were recovered by rinsing the vegetables with distilled water, centrifuging the rinse water, and transferring the sediment to agar plates on which a bacterial lawn had previously been grown; trophozoites identified as the potentially pathogenic species--Acanthamoeba polyphaga, A. rhysodes, and A. castellanii--were the most common amoebae recovered on the plates. Salmonella spp. were grown from 4 of 50 samples.

Recovery of eggs of two parasitic nematodes, Ascaris sp. and Trichuris sp.: Interlaboratory study.

An interlaboratory study was conducted to determine the effectiveness of the Nacconol ether centrifugation method for recovering parasitic nematode eggs from 3 contaminated products: a crop (cabbage), a sludge fertilizer (Milorganite), and a sewage effluent (Minneapolis). Six replicate samples for each of the 3 products were seeded with eggs at 3 different levels: 200 Ascaris suis and 8 Trichuris muris; 15 A.suis and 15 T.muris; 8 A.suis and 180 T.muris. Recovery was low for all samples except sewage effluent, in which recoveries greater than 100% in 2 samples resulted from the misidentification of arthropod eggs as Ascaris sp. The average mean percent recovery for the other samples was 22.53. Repeatability for replicate samples and reproducibility of results by individual laboratories were poor, and the method is not recommended for quantitative estimates of nematode egg contamination of foods and food-contact materials. However, the Nacconol ether centrifugation method can be used as an all-or-none test. (Only 13% of 1146 counts were falsely negative.) Of 69 samples, only 4 were falsely negative for A.suis eggs and only 1 was falsely negative for T.muris eggs in counts of 6 replicates.

Recovery of parasitic nematodes from fish by digestion or elution.

Two methods, digestion and elution, were used to recover parasitic nematodes from 470 flatfish belonging to species in the family Pleuronectidae. Samples of similar fish were collected from market lots; half of each sample was subjected to digestion, and half was subjected to elution (sedimentation). The edible (flesh) and the inedible (viscera) portions of each fish were analyzed separately. The total number of nematodes recovered by digestion was 1,110, which was not significantly greater than the 922 nematodes recovered by elution. However, digestion recovered 1,062 nematodes of the anisakine genera Anisakis and Phocanema, which are potentially pathogenic for human consumers of raw of semiraw fish. This number is significantly greater than the 608 pathogenic nematodes recovered by elution. Digestion also recovered 242 more nematodes from the edible flesh than did elution. Conversely, more nonpathogenic nematodes were recovered by elution. Approximately half the fish (240) had been collected in Boston markets, and the other half (230) had been collected in San Francisco markets. Fish from San Francisco each contained an average of eight nematodes, and those from Boston contained an average of less than one nematode per fish.

Amino acid, heme, and sterol requirements of the nematode, Rhabditis maupasi.

Rhabditis maupasi, a nematode that occurs in the mantle cavity of Helix aspersa and related North African food snails, requires 5 amino acids (lysine, methionine, phenylalanine, tryptophane and valine) for maintenance of the stage-3 survival larvae, and 5 additional amino acids (arginine, isoleucine, leucine, threonine and, marginally, histidine) for development of these larvae into adults and for reproduction. Tyrosine is beneficial but not absolutely required for reproduction. These results were obtained with axenic R. maupasi grown in a chemically defined medium containing salts, trace metals, purines and pyrimidines, Krebs cycle intermediates, a fatty acid (butyric), vitamins, urea, and a carbohydrate (dextrose). The complete medium contained 18 amino acids; each of 18 test media was deficient in one of the amino acids. In the complete medium and in a medium lacking the "nematode nonessential" amino acids, stage-3 R. maupasi developed into adults and produced one generation of offspring. For continuous cultivation, however, the nematode also required hemin or another iron porphyrin as well as a sterol such as cholesterol.