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Biomedical subjects

B A Rubin

Publications and source records attributed to B A Rubin.

At least 37 records · Page 2Linked to original sources
PubMed1976

Morphological components of herpesvirus. II. Preservation of virus during negative staining procedures.

The disruption of envelopes and the fragmentation of capsids of equine herpes-virus type I observed in negatively stained samples were attributed to viral dehydration on carbon films during preparation for electron microscopy. Prior fixation of virus with OSO4 or glutaraldehyde and subsequent application of negative stain before drying minimized envelope disruption and virtually eliminated the occurrence of capsomere sheets and broken capsids. This sample procedure significantly improves electron microscopic evaluation of herpesvirus samples.

Animals↗
PubMed1976

Development of a purified cholera toxoid. III. Refinements in purification of toxin and methods for the determination of residual somatic antigen.

The addition of an ultrafiltration step to the purification procedures previously described for cholera toxin (Rappaport et al., (1974) permitted the preparation of highly purified antigenic toxoids essentially free of somatic antigen(s). The purity of such toxoids is established: (i) by the absence of more than about one part limulus amebocyte lysate (LAL)-positive endotoxin per 10(5) parts toxoid and (ii) by the inability of the toxoids to elicit a significant rise in rabbit vibriocidal antibody. The antigenicity of the toxoids is demonstrated by their ability to produce the same high levels of rabbit serum antitoxin as are produced by comparable toxoids containing small amounts of somatic antigen. The results also indicate that amounts of somatic antigen of the order of less than or equal to 1 mug/100 mug of toxoid do not exert an adjuvant effect on the toxoid, at least with respect to circulating antitoxin. Other data show that, where present, the ability of somatic antigen to elicit vibriocidal antibody is influenced by the immunization schedule employed and that a correlation exists between the LAL-determined endotoxin content of the toxoids and their ability to stimulate vibriocidal antibody. Somatic antigen-free toxoids, purified and tested by the refinements herein described, were prepared for use in the National Institutes of Health sponsored field trials, and data pertaining to their purity and antigenic properties are presented.

Animals↗
PubMed1976

[Localization of the Meler's reaction with ethanol catalase trap in the chain of photosynthetic electron transport].

The common view of photosystem I as the action site of catalase and ethanol at oxygen uptake in chloroplasts are based on indirect data on this reaction. That is why the question on Mehler reaction localization in electron transport chain with ethanolcatalase trap has been investigated anew. It has been demonstrated that oxygen uptake with catalase and ethanol does not decrease in presence of dibromothymoquinone (2,5-dibromo-3-methyl-6 isopropyl-p-benzoquinone--DBTQ) which blocks electron transfer to photosystem I at plastoquinones level. The summation of oxygen uptake activities is observed on the combined action of catalase and ethanol with any of the Mehler reagents functioning in photosystem I (methylviologen,FMN, epinephrine, ferredoxin). Catalase and ethanol in contrast to methylviologen have no effect on photooxidation rate of reduced dichlorphenolindophenol in photosystem I. The quatum yield of oxygen uptake with catalase and ethanol versus wave length of actinic light shows a distinct maximum in the photosystem II absorption area and a "red drop" in the longware area. The obtained data show that the Mehler reaction with catalase and ethanol takes place in photosystem II only.

2,6-Dichloroindophenol↗
PubMed1974

Development of a purified cholera toxoid. I. Purification of toxin.

The enterotoxin from Vibrio cholerae is selectively concentrated from cell-free culture supernatant by co-precipitation with hexametaphosphate and is further purified by adsorption on aluminum hydroxide powder. The bulk of residual somatic antigen becomes insoluble upon lyophilization of the toxin preparation and is removed by centrifugation of the rehydrated material. Other contaminants are eliminated by treatment with activated carbon. Preparations of toxin, purified by this method, have been characterized by: (i) a single immunoprecipitin line against polyvalent antisera; (ii) homogeneity on acrylamide gels; (iii) specific activities on the order of 22 limit-of-bluing doses/mug; (iv) ultraviolet spectra characteristic of pure protein; and (v) overall yields on the order of 50%, irrespective of purification scale. Such preparations, however, have been shown to contain trace amounts of somatic antigen when they are intensively tested either for their ability to elevate serum vibriocidal antibody titers in immunized rabbits or for their ability to increase resistance of immunized mice to live vibrio challenge. In the latter test system, the level of residual somatic antigen per 50 mug of toxin (toxoid) antigen generally did not exceed 0.025% of the Division of Biological Standards reference vaccine, V. cholerae Inaba IN-12. Methods for elimination of this small amount of somatic antigen have been investigated and are discussed. The particular combination of purification steps which are presently described have been easily and reproducibly applied on a production scale to prepare gram amounts of toxin with a high degree of purity, even under a variety of initial conditions.

Adsorption↗
PubMed1974

Development of a purified cholera toxoid. II. Preparation of a stable, antigenic toxoid by reaction of purified toxin with glutaraldehyde.

Evidence is presented which confirms that cholera toxoids obtained by reaction of purified toxin with Formalin possess the ability to partially reactivate both in vivo and in vitro. At the same time, conditions are presented for the preparation of stable, antigenic cholera toxoids by reaction of purified toxin with glutaraldehyde. Treatment of purified cholera toxin with approximately 200 mol of glutaraldehyde per mol of toxin at pH 7.8 reproducibly resulted in the preparation of toxoids which: (i) possessed less than 20 bluing doses per 100 mug; (ii) did not reactivate in vivo or in vitro; (iii) precipitated with, and neutralized antitoxin; (iv) elevated prolonged serum antitoxin in immunized rabbits; (v) protected immunized guinea pigs against toxin skin challenge; and (vi) lent themselves to enhanced antigenicity by means of an in situ adjuvant system which may be suitable for man. Acrylamide gel electrophoresis and molecular sieve chromatography of a series of glutaraldehyde-derived toxoids suggested that the reaction products consisted of monomeric and polymeric species and that the proportion of higher-molecular-weight species was determined by the relative concentrations of toxin and glutaraldehyde. The results suggested a relationship between complete and irreversible elimination of toxicity and the formation of higher-molecular-weight toxoids.

Adsorption↗