Ameba

ArndbOt /. (Zodl.) amoeba, ameba. amorph, amorpbiacht a. amorpho js. amortisieren, v.t. amortize. 

Amebicides (drugs that kill amebas) are used to treat amebiasis caused by the parasite E. histolytica. An ameba is a one-celled organism found in soil and water. Examples of amebicides are listed in the Summary Drug Table Amebicides. 

These dragp are amebicidal (ie, they kill amebas). There are two types of amebiasis intestinal and extradntestinal. 

In the intestinal form, the ameba is confined to the intestine In the extradntestinal fonn, the ameba is found outside of the intestine, such as in the liver. The extradn-testinal fonn of amebiasis is more difficult to treat. 

Follow directions Take the drug exactiy as prescribed. Complete the full course of therapy to eradicate the ameba. Failure to complete treatment may result in a return of the infection. 

Chef/waitstaff Food handlers should not resume work until a full course of treatment is completed and stools do not contain the ameba... 

Fivush AM, Willson TM. AMEBA An acid sensitive aldehyde resin for solid phase synthesis. Tetrahedron Lett 1997 38 7151-7154. 

A number of substances may interfere with stool examination. Particulate materials such as barium, antacids, kaolin, and bismuth compounds interfere with morphologic examination, and oily materials such as mineral oil create small, refractile droplets that make examination difficult. Antimicrobial agents, particularly broad-spectrum antimicrobial agents, may suppress amebae. If any of these substances have been used, specimens should not be submitted until the substances have been cleared (generally 5 to 10 days). A fecal specimen may appear satisfactory by gross examination when there is still barium, etc., which can interfere with microscopic examination. 

Biopsy material for amebiasis should be processed for surgical pathology and then examined for ulcers containing amebae. The periodic acid-Schiff stain counterstained with hematoxylin is particularly helpful because amebae stain more positively with periodic acid-Schiff stain than do inflammatory cells, and amebae show typical amebic nuclei. Of course, there are no amebic cysts in tissue. 

The last material aspirated is most likely to contain amebae. Material may be examined microscopically in wet mounts and permanent stains, and in addition, it can be cultured for amebae if bacteria are also added to the culture as described below. Abscess material is often thick and difficult to examine. It may be treated with streptokinase and streptodonase enzymes to liquefy the specimen. 

The sediment may be used for microscopic examinations for amebae (wet mounts and permanent stains) and for the culture of amebae. 

A variety of culture media for amebae have been described, and some may be purchased from commercial mecuum manufacturers. The method described here uses the modified charcoal agar slant diphasic medium described by McQuay. 

Amebae Prepare films fixed in Schaudinn fixative, or fix a portion in PVA fixative. 

Free-living amebae Sigmoidoscopic material Fix films in Schaudinn fixative or mix material with PVA fixative. 

Ingalls, H.M., Goodloe-Holland, C.M., and Luna, E.J. (1986) Junctional plasma membrane domains isolated from aggregating Dictyostelium discoideum amebae. Proc. Natl Acad. Sci. USA 83, 4779-4783. 

Scheme 7.93 Preparation of an N-imidazolium-based soluble AMEBA linker.

In a recent study, the group of Buijsman presented a microwave-mediated preparation of a different N-imidazolium-based ionic analogue of the well-known AMEBA solid support (Scheme 7.93). With this soluble support, a set of various sulfonamides and amides was prepared, and furthermore the use of this novel linker in the synthesis of a potent analogue of the antiplatelet drug tirofiban was presented [106]. 

Preparation of AMEBA Resin A from SASRIN Resin,... 

A total of 10.0 g (8.9 mmol) SASRIN resin2 (note 1) was washed with N,N-dimethyIfonnamide (DMF 2 x 25 mL), methanol (MeOH 2 x 25 mL), and dichloromethane (DCM note 2 2 x 25 mL), and dried under vacuum (0.5 torr) at 70°C overnight. To a suspension of the dried SASRIN resin in lOOmL of methyl sulfoxide (DMSO note 2) and 25 mL of DCM was added 12.4 mL (89 mmol, 10.0 Eq.) triethylamine (note 2) followed by 7.1 g (44.5 mmol, 5.0 Eq.) sulfur trioxide-pyridine complex (note 2). The suspension was shaken on a radial arm at room temperature overnight (note 3) filtered on a glass frit and washed with DCM (3 x 100mL), DMSO (3 x lOOmL), DCM (3 x lOOmL), and tetrahydrofuran (THF 3 x 100 mL) and dried under vacuum (0.5 torr) at room temperature to give 10.0 g Ameba resin (notes 4 and 5). 

Preparation of Ameba Resins Ba-Bd from Merrifield Resin3... 

Ameba resin Bb (Table 10.1) was prepared from 1.00 g (1.10 mmol) Merrifield resin (HL, 100-200 mesh note 6) in... 

TABLE 10.1. Ameba Resin Loading Values and Yields for Sulfonamide (1)... 

Prepared Starting Resin Loading (mmol/g) Calculated Loading of AMEBA Resin (mmol/g) Sulfonamide Yield (%) ... 

For the preparation of N- 2-(methoxyphenyl)cthyl ]-4-mcthylbcn-zenesulfonamide (1) from Ameba resins A and Ba-Bd, 100 mg (0.089 mmol) Ameba resin A was added to a glass peptide reaction vessel, suspended in 3.0 mL 1,2-dichloroethane (DCE note 2), and treated with 26 pL (0.18 mmol, 2.0 Eq.) 2-(4-methoxy-phenyl)ethylamine (note 2) and 38 mg (0.178 mmol, 2.0 Eq.) sodium triacetoxyborohydride (note 2). The suspension was shaken for 1 h treated with 5 mL MeOH filtered on a glass frit and washed with DCM (2x5 mL), DMF (2x5 mL), MeOH (2 x 5 mL), and DCM (2x5 mL). The resin was dried under vacuum (0.5 torr) at room temperature overnight. The resin was suspended in 1.5 mL DCM, treated with 155 pL (0.89 mmol, 10.0 Eq.) N,N-diisopropylethylamine (note 2) and 85 mg (0.445 mmol, 5.0 Eq.) p-toluenesulfonyl chloride (note 2), and shaken for 3.5 h. The reaction mixture was filtered on a glass frit, washed with DCM (2 x 5 mL), DMF (2x5 mL), MeOH (2x5 mL), and DCM (2 x 5 mL), and dried under vacuum (0.5 torr) at room temperature for 2h. The resin was treated with 2.5 mL of a solution of 5% trifluoroacetic acid (note 2) in DCM, shaken for 15 min, filtered on a glass frit, and washed with DCM (3x5 mL). The combined filtrate and washings were concentrated and dried under vacuum (0.5 torr) at room temperature overnight to afford 18.0 mg (66%) N- [2-(methoxyphenyl)ethyl] -4-methylbenzenesulfonamide (1). 

Ameba resin A loading was assumed to be 0.89 mmol/g, based on the loading of the starting SASRIN resin. 

Ameba resin was characterized by the diagnostic aldehyde signal at 10.5 ppm using Nanoprobe JH NMR.4 Checkers characterized Ameba resin by the diagnostic aldehyde signals at 1675-1684 cm 1 using IR. 

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