Cholera incubation

Figure 2 Principle of spectral bio-imaging HUVEC incubated with pH-sensitive DOPE CHEMS liposomes (loaded with fluorescein isothiocyanate-dextran), cholera toxin subunit B (Alexa Fluor 594 labeled), and diamidino-phenylindole-dihydrochloride.

The following experiments arc at variance with such a clearance mechanism. Incubation of rabbit erythrocytes with V. cholerae sialidase in the presence of inhibiting concentrations of Neu2en5Ac protects surface sialic acids and, correspondingly, survival of the cells in circulation.142 Treatment of erythrocytes by V. cholerae sialidase immobilized on Sepharose 4B, allowing complete separation of the enzyme from the cells after incubation, resulted in engulfment of these cells by macrophages at a rate similar to that observed with cells treated with the soluble enzyme. 1 1... 

Fig. 18.9. (A) Schematic presentation of biotinylated polypyrrole-ruthenium electrode in presence of an oxidative quencher and the resulting photocurrent response by switching the excitation light on and off. (B) Reduced photocurrent response and schematic presentation of the polypyrrole-ruthenium electrode after incubation in anti-cholera toxin solution.

The immunosensors are incubated for 20 min with anti-cholera toxin... 

Lipid extracts treated with neuraminidase were dried under N2 and incubated at 37° with 50 ul (25 units) V.cholerae neuraminidase. After 16 hr, 1 ml C M (2 1) was added, the samples were incubated... 

The average incubation period for V. cholerae infection is 1 to 3 days. The clinical presentation can vary from asymptomatic to life-threatening dehydration owing to watery diarrhea. The onset of diarrhea is abrupt and is followed rapidly or sometimes preceded by vomiting. Initial stools generally do not have the rice water appearance that is classically noted with cholera. Fever occurs in less than 5% of patients, and the physical examination correlates weU with the severity of dehydration. In the most severe state, this disease can progress to death in 2 to 4 hours if not treated. In some cases, fluid accumulates within the intestinal lumen causing abdominal distension and ileus and may cause intravascular depletion without diarrhea. Patients may lose up to 1 liter of isotonic fluid every hour. 

Figure 8.26 P P]ADP-ribosylation of platelet membrane proteins after pretreatment with iloprost. Platelets were incubated for 24 h in the absence (lanes 1—3) or presence (lanes 4—6) of 10 )Umol iloprost. Platelet membranes were prepared, and ADP-ribosylation of membrane proteins performed in the presence of cholera toxin (A subunit). The gels were loaded with (lanes 1-6) 3.95, 9.88, 39.5, 3.05, 7.63, 30.5 fig protein. The figure shows the autoradiograph of the 6 lanes, and a densitometer scan of lanes 3 and 6. In a control experiment, there was no significant labelling of the platelet membrane proteins in an incubation from which cholera toxin had been omitted. (Reproduced from reference 35 with permission)...

After an incubation period of 12 to 72 hours, the disease suddenly presents with abdominal cramping and then painless, profuse rice water diarrhea (5—10 liters per day). Some patients may also have vomiting, weakness, and headache. Fever, if present, is low-grade. The response to infection varies greatly. Many patients have few or no symptoms (400 1 ratio of asymptomatic to symptomatic) others lose massive amounts of fluids and develop hypovolemic shock. As with other diseases, cholera is worse in the very young and very old. Deaths are from fluid loss and electrolyte abnormalities. 

Fig. 2. (right) ADP-ribosylation of a specific protein in bovine adrenal membranes by type D botulinum toxin. Membranes of bovine adrenal gland (100 pg) were incubated with 20 pg of type D botulinum neurotoxin and [ P]NAD at 30°C for 45 min, acid-precipitated, and subjected to SDS-polyacrylamide gel electrophoresis. Lane 1, control without the toxin lane 2, with the toxin lane 3, with the toxin plus 10 mM dithiothreitol lane 4, with the toxin plus 25 mM agmatine lane 5, with the toxin plus 25 mM L-arginine methyl ester lane 6, with 20 pg of cholera toxin. Reproduced from ref 5. 

Epidemic cholera is a common cause of illness in countries with inadequate water treatment facilities. Cholera excretes a toxin (choleragen) consisting of a binding agent that attaches the microbe to the intestinal wall. The microbe then penetrates mucus layers, which produces the classic symptom of diarrhea. In the case of Asiatic cholera, untreated cases of infection have an approximate fatality rate of over 60 percent. Diarrhea, vomiting, and malaise appear after an incubation period from 12 hours to 3 days, symptoms caused by severe water loss and subsequent lack of body electrolytes. 

Sialic acid was the first virus receptor identified. Hirst and McClelland and Hare discovered that influenza virus is able to hemagglutinate and that adsorbed virus is eluted from erythrocytes on incubation at 37°C, indicating an enzymatic destruction of a receptor substance on the cells [1, 2]. When a similar enzymatic activity was subsequently detected in Vibrio cholerae cultures, the term receptor-destroying enzyme was introduced [3]. The substance released by the viral enzyme from soluble hemagglutination inhibitors was initially characterized as a carbohydrate of low molecular weight [4] and then identified in crystalline form as A-acetyl-o-neuraminic acid [5]. Thus, it was clear that the receptor determinant of influenza virus was sialic acid and that the viral enzyme was a neuraminidase. Furthermore, for the first time an important biological function of sialic acid had been identified. 

---