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Results for “Allantoin”

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At least 19 recordsLinked to original sources

PubMed1978

Induction and inhibition of the allantoin permease in Saccharomyces cerevisiae.

Allantoin uptake in Saccharomyces cerevisiae is mediated by an energy-dependent, low-Km, active transport system. However, there is at present little information concerning its regulation. In view of this, we investigated the control of alloantoin transport and found that it was regulated quite differently from the other pathway components. Preincubation of appropriate mutant cultures with purified allantoate (commercial preparations contain 17% allantoin), urea, or oxalurate did not significantly increase allantoin uptake. Preincubation with allantoin, however, resulted in a 10- to 15-fold increase in the rate of allantoin accumulation. Two allantoin analogs were also found to elicit dramatic increases in allantoin uptake. Hydantoin and hydantoin acetic acid were able to induce allantoin transport to 63 and 95% of the levels observed with allantoin. Neither of these compounds was able to serve as a sole nitrogen source for S. cerevisiae, and they may be non-metabolizable inducers of the allantoin permease. The rna1 gene product appeared to be required for allantoin permease induction, suggesting that control was exerted at the level of gene expression. In addition, we have shown that allantoin uptake is not unidirectional; efflux merely occurs at a very low rate. Allantoin uptake is also transinhibited by addition of certain amino acids to the culture medium, and several models concerning the operation of such inhibition were discussed.

Allantoin↗

PubMed1977

Renal excretion of allantoin in rats: a micropuncture and clearance study.

Free-flow micropuncture and clearance studies were performed to evaluate the transport of allantoin inthe rat kidney. Inn all studies [2-14C]uric acid and [methoxy-3H]inulin were administered. With a two-step column chromatographic technique, radiolabeled uric acid and allantoin were separated in plasma, urine, and tubular fluid, and the [2-14C]allantoin concentration was determined. Tubular fluid collections were obtained under hydropenic and control coneated animals in the control and volume-expanded states. Clearance data were obtained in oxonic acid-treated animals under the same experimental conditions. These studies indicate that allantoin is not bound to plasma protein and is, therefore, freely filterable. Neither net reabsorption nor net secretion of allantoin was evident along the length of the nephron. The bubular handling of allantoin was demonstrated to be dissociated from that of uric acid in all experimental states. No significant intrarenal production of allantoin from uric acid was observed.

Allantoin↗

PubMed1978

Enzymic racemization of allantoin.

Allantoin racemase was isolated from cells of Candida utilis, and purified by chromatography on columns of DEAE-cellulose and Sephadex G-100. Using this purified enzyme, the racemization of allantoin in deuterium oxide was investigated. Polarimetric and PMR spectroscopic analyses showed that racemization of allantoin by the enzyme proceeded in parrallel with release of the hydrogen atom (5-H) attached to the asymmetric carbon (C-5) of allantoin. Non-enzymic racemization of allantoin, which was examined for comparison, however, was accompanied by much less or almost no release of allantoin 5-H. This indicates that the mechanism of racemization by the enzyme differs from that of non-enzymic racemization.

Allantoin↗

PubMed1977

Allantoin transport in Saccharomyces cerevisiae.

Allantoin uptake in both growing and resting cultures of Saccharomyces cerevisiae occurs by a low-Km (ca. 15 micrometer) transport system that uses energy that is likely generated in the cytoplasm. This conclusion was based on the observation that transport did not occur in the absence of glucose or the presence of dinitrophenol, carbonyl cyanide-m-chloro-phenyl hydrazine, fluoride, or arsenate ions. Normal uptake was observed, however, in the presence of cyanide. The rate of accumulation was maximal at pH 5.2. In contrast to the urea transport system, allantoin uptake appeared to be unidirectional. Preloaded, radioactive allantoin was not lost from cells suspended in allantoin-free buffer and did not exchange with exogenously added, nonradioactive allantoin. Treatment of preloaded cells with nystatin, however, released the accumulated radioactivity. Allantoin accumulated within cells was isolated and shown to be chemically unaltered.

Allantoin↗

PubMed1977

The use of silver-zinc-allantoin powder for the prehospital treatment of burns.

We describe our experimental studies of a powder formulated to treat serious burn wounds on-the-scene. The wound powder comprises two parts silver-citro-allantoinate, two parts zinc allantoinate and 96 parts pure allantoin. The back skin of 62 rats was shaved and exposed to actively boiling water for ten seconds, resulting in third degree burns of 20% of the total body surface. Immediately, 1 ml of a culture containing 2 X 10(8) Pseudomonas aeruginosa was applied to the burn. The animals were isolated. Of the 30 control rats, six were powdered with allantoin only. Thirty-two rats were dusted with the silver-zinc-allantoin powder within 15 minutes of burning. Cultures were taken at 48 hour intervals. Eighty-seven percent of the control animals died an average of six days postburn. In the treated animals, the mortality was 15%. A mean of 27% of the applied silver (0.35 gm) became incorporated in the eschar. In all control rats, sepsis was detected under the eschar. In treated animals, bacterial concentration fell from an initial average of 5 X 10(4) at 4 hours postburn to 6 X 10(2) at 96 hours.

Allantoin↗

PubMed1979

The effect of allantoin on cellular multiplication in degenerating and regenerating nerves.

Injury to a peripheral nerve is, among other things, followed by degeneration of axons and myelin, as well as by a sharp increase in the number of cells (especially Schwann cells) in the part distal to the injury. The effect of allantoin--a cell proliferant--was tested on the above-mentioned reactions in the sciatic nerve of rats. The nerves were crushed and re-exposed 7, 14, 21, 35 and 90 days after the injury, and removed for histological examination. The results obtained in a group of rats treated with allantoin were compared with those obtained in a control group of rats. The results showed that allantoin had a statistically significant effect on the cellular multiplication seen in the nerve 7 and 14 days after the injury. Myelin degeneration was also found to be more advanced in the allantoin-treated nerve preparations examined 14 and 21 days postoperatively than in the control nerve preparations.

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PubMed1975

Allantoin racemase: a new enzyme from Pseudomonas species.

1. Allantoin racemase is a novel enzyme which catalyzes the conversion of S(+)-and R(minus)-allantoin into the racemate. 2. The enzyme is present in Pseudomonas testosteroni, Pseudomonas putida and five biotypes of Pseudomonas fluorescens, but absent in a number of other Pseudomonas species. 3. The enzyme of Ps. testosteroni was purified 133-fold and exposes optimal activity at pH 8.0-8.2 and 50 degrees C. The enzyme is stable on heating for 15 min at 70 degrees C. 4. The enzyme appeared to be specific for the optical isomers of allantoin and no cofactors are involved in the reaction. 5. The optical aspecificity of allantoinase of Proteus rettgeri was reaffirmed.

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PubMed1977

A trial of silver-zinc-allantoinate in the treatment of leg ulcers.

Three hundred thirty-nine of 400 chronic cutaneous ulcers in 264 patients (including some with multiple or bilateral ulcers of both) were healed with silver-zinc-allantoinate creamed (AZAC 1%). Some of the patients treated had failed to respond to medicated wrappings, saline dressings, and various other therapeutic agents, including antibiotics. In one week of treatment with AZAC 1%, bacterial counts were reduced on the average from approximately 2 X 10(7) to 2 X 10(5) (99%). Silver-zinc-allantoinate cream also demonstrated a wide spectrum of antimicrobial activity. It did not give rise to resistance by the infecting organisms, was nonallergenic, debrided necrotic tissue, and stimulated healthy granulation. Treatment was well tolerated, side effects being limited to a burning sensation in three patients. Most patients cared for themselves at home with minimal interference in their usual daily activities.

Administration, Topical↗

PubMed1979

A cluster of three genes responsible for allantoin degradation in Saccharomyces cerevisiae.

Mutant strains of Saccharomyces cerevisiae unable to utilize allantoin as sole nitrogen source were isolated and divided into three groups on the basis of their biochemical and genetic characteristics. The three loci associated with these mutant classes were designated dal1 (allantoinase minus), dal2 (allantoicase minus) and dal4 (allantoin transport minus). All three loci are located in a cluster that is proximal to the lys1 locus on the right arm of chromosome IX. The gene order and intergenic distances were estimated to be: dal1--2.5 cM--dal4--1.9cM--dal2--4.6cM-lys1.

Allantoin↗

PubMed1977

[Action of benzbromarone on the renal excretion of allantoin in normouricemic and hyperuricemic humans (author's transl)].

Oral administration of benzbromarone at daily doses of 100 mg or 300 mg over a period of 3 or 6 days does not produce a significant change of the excretion rates of allantoin in the 24-h-urines of humans in a normouricemic or hyperuricemic state. Threrefore, the theroretically improbable assumption that benzbromarone may induce an increased elimination of uric acid by an enteral pathway cannot be accepted any longer. Failing additional direct effects upon purine metabolic pathways (Sorensen and Levinson, 1976) benzbromarone exerts its hypouricemic action solely by uricosuric properties.

Adult↗

PubMed1977