Identification and nucleotide sequence of a developmentally regulated gene encoding a eukaryotic histone H1-like protein from Chlamydia trachomatis

A lambda gt11 recombinant library of Chlamydia trachomatis serovar L2 chromosomal DNA was screened with a 29-mer synthetic oligonucleotide specific to the N-terminal amino acids of a predominant 18-kDa chlamydial protein. One recombinant clone, designated lambda gt11/L2/RKA10, was selected on the basis of its strong hybridization signal. Restriction endonuclease analysis and complete nucleotide sequencing of the recombinant revealed a 2,633-bp insert containing one complete open reading frame (ORF2) and two partial ORFs (ORF1 and ORF3). The deduced amino acid sequence of ORF2 matched perfectly at its N-terminal end with the derived amino acid sequence. The 375-bp ORF is capable of encoding a protein comprising 125 amino acids with a molecular mass of 13,689. A sequence compatible with a Shine-Dalgarno ribosome-binding site was located 9 bp upstream from the initiation codon, while the sequence distal to ORF2 revealed a rho-independent terminator. The protein, designated CTH1, possesses an estimated pI of 10.71 due to its high lysine content. This highly basic protein contains no tryptophan or phenylalanine. A protein data base search identified significant homology between CTH1 and painted sea urchin histone H1. Northern (RNA) blot analysis of Chlamydia-infected host cells demonstrated transcripts at 12 h postinfection. The recombinant plasmid encoding ORF2 expressed a gene product of approximately 18 kDa, similar to the native chlamydial protein as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This protein appears to represent one of the few eukaryotic histonelike proteins described to date in prokaryotes.

Purification, characterization, and localization of aspartoacylase from bovine brain

Canavan disease, an autosomal recessive disorder, is characterized biochemically by N-acetylaspartic aciduria and aspartoacylase (N-acyl-L-aspartate amidohydrolase; EC 3.5.1.15) deficiency. However, the role of aspartoacylase and N-acetylaspartic acid in brain metabolism is unknown. Aspartoacylase has been purified to apparent homogeneity with a specific activity of approximately 19,000-20,000 nmol of aspartate released/mg of protein. The native enzyme is a 58-kDa monomer. The purified aspartoacylase activity is enhanced by divalent cations, nonionic detergents, and dithiothreitol. Low levels of dithiothreitol or beta-mercaptoethanol are required for enzyme stability. Aspartoacylase has a Km of 8.5 x 10(-4) M and a Vmax of 43,000 nmol/min/mg of protein. Inhibition of aspartoacylase by glycyl-L-aspartate and amino derivatives of D-aspartic acid suggests that the carbon backbone of the substrate is primarily involved in its interaction with the active site and that a blocked amino group is essential for the catalytic activity of aspartoacylase. Biochemical and immunocytochemical studies revealed that aspartoacylase is localized to white matter, whereas the N-acetylaspartic acid concentration is threefold higher in gray matter than in white matter. Our studies so far indicate that aspartoacylase is conserved across species during evolution and suggest a significant role for aspartoacylase and N-acetylaspartic acid in normal brain biology.

Defective thermoregulatory thermogenesis does not cause onset of obesity in Zucker rats

To test whether or not the onset of obesity in fatty (fa/fa) Zucker rats is caused by decreased thermoregulatory thermogenesis, pups were artificially reared above their lower critical temperature from 3 or 4 days of age. Littermates were continuously fed identical amounts of synthetic rat milk while body temperature (Tc) and oxygen consumption rate (VO2) were continuously recorded. When the daily mean Tc of all pups was held greater than 37 degrees C, neither Tc nor VO2 differed between fa/fa and genetically lean (Fa/-) pups during the first 2 wk of life. Tc and VO2 were significantly elevated in Fa/- pups during the third postnatal week. At both 16 and 21 days of age, fa/fa pups were identified by their low Tc during a brief cold exposure. Body fat and fat-free dry mass of fa/fa and Fa/- littermates differed at 21 but not at 16 days of age. The excess energy deposited as fat was partly derived from decreased nonthermoregulatory energy expenditure and decreased synthesis of lean body mass. Calculations support the speculation that a greater extraction of energy from the synthetic diet additionally supports the excess fat deposition. Decreased thermoregulatory thermogenesis and excess fat storage appear to be secondary and independent consequences of the primary genetic lesion.

Cyclic AMP inhibits protein synthesis in Chlamydia trachomatis at a transcriptional level

Cyclic AMP (cAMP) has an inhibitory effect on the developmental cycle of Chlamydia trachomatis. We examined its influence on the synthesis of chlamydial protein, using the major outer membrane protein (MOMP) as a marker for general chlamydial protein synthesis. During normal development MOMP synthesis accelerates from 18 h post-infection and peaks by 36 h. Cyclic AMP blocks this normal progression of the chlamydial growth cycle. At a concentration of 1 mM, nearly 75% of the total MOMP synthesis was inhibited by 36 h, as monitored by radiolabel uptake. However, no difference was observed during the first 12 h between cAMP-treated and control groups, a finding which is in keeping with correlation between developmental inhibition and protein synthesis. Hybridization studies carried out with a cloned MOMP gene demonstrate a drastic decrease in MOMP mRNA in cAMP-treated cells. Low levels of cAMP utilized in conjunction with a 100,000 x g supernatant from reticulate bodies (RBs) blocked the transcription of the recombinant MOMP gene in an in vitro transcription system. These results suggest that the inhibition of chlamydial protein synthesis, assessed by MOMP synthesis, is due to regulation at a transcriptional level.

Detection of the surface-exposed 18-kilodalton binding protein in Chlamydia trachomatis by immunogold staining

Dot-blot analysis of Chlamydia trachomatis elementary bodies (EBs) with monospecific polyclonal antibodies demonstrated that the 18-kilodalton binding protein is surface exposed. Immunoelectron microscopy with whole serovar L2 EBs and ultrathin sections confirmed this finding. In addition, only the extracellular EBs and not the intracellular reticulate bodies were labeled with immunogold.

Expression of the Chlamydia trachomatis major outer membrane protein-encoding gene in Escherichia coli: role of the 3' end in mRNA stability

The major outer membrane protein (MOMP)-encoding gene (omp1) of Chlamydia trachomatis has been cloned into Escherichia coli and partially sequenced. This recombinant gene expresses a full-length 40-kDa product, which is recognized by a monoclonal antibody directed against the species-specific epitope of MOMP. The recombinant omp1 is expressed in either insertion orientation, indicating that it utilizes its own promoter system. The endogenous omp1 promoter possesses a relatively low activity despite the high level of MOMP expression. Deletion of a 520-bp fragment at the 3' end encoding 39 amino acids (aa) at the C terminus and the remainder of the noncoding region leads to a significant decrease in mRNA stability and loss of protein synthesis. When the MOMP-encoding plasmid was introduced into E. coli minicells, it expressed 40- and 43-kDa proteins; however, inhibition of post-translational processing by ethanol revealed only a 43-kDa protein. These data indicate that the unprocessed omp1 gene product contains a 22-aa leader sequence which is cleaved during translocation to the outer membrane, to yield a processed 40-kDa protein. The recombinant MOMP was localized to the outer membrane E. coli fraction, comparable to the location of the native C. trachomatis protein.

Bone marrow transplantation for familial hemophagocytic lymphohistiocytosis

A one year old child diagnosed at two months as having familial hemophagocytic lymphohistiocytosis had a partial response to etoposide. He relapsed and underwent a bone marrow transplant after conditioning with etoposide 65 mg/kg, total body irradiation and cyclophosphamide 60 mg/kg X 2 doses. Post transplant sepsis ensued and the patient expired. At autopsy residual disease was noted. Familial hemophagocytic lymphohistiocytosis continues to be a fatal disorder and etoposide is the only agent known so far with any efficacy. Bone marrow transplantation probably should be attempted early in its course and may have a role in the treatment of this disease.

[Penetration and action of edoxudine in vitro and in vivo]

The penetration of 5-ethyl-2'-deoxyuridine (edoxudine, Aedurid) from gel base with and without the addition of urea and other adjuvant has been studied in an in vitro model using guinea pig skin. The formulation of 3% edoxudine gel with 5% urea showed the best results. In vivo experiments on hairless mice infected intracutaneously with herpes simplex virus type 1 also showed this formulation's good efficacy as compared to other formulations.

Initial characterization of a chlamydial receptor on mammalian cells

We have examined characteristics of the binding of eukaryotic cells to chlamydial elementary body (EB)-specific proteins. A wide variety of eukaryotic cell lines bound to representatives of both Chlamydia trachomatis lymphogranuloma venereum (LGV) and trachoma biovars and a C. psittaci strain meningopneumonitis (Mn) suggesting the presence of a common host cell receptor. Neither tunicamycin nor neuraminidase treatment of HeLa cells impaired binding to C. trachomatis EB, implying that host cell N-linked carbohydrate domains and sialic acid moieties, respectively, are not involved in attachment. However, trypsinized HeLa cells do not bind to EB, suggestive of a proteinaceous host cell receptor. The trypsin sensitivity of two EB-specific binding proteins Mr = 18,000 and 31,000) was also examined, and the finding that 125I-labeled HeLa cells bind both the 18,000 and 31,000-dalton proteins after chlamydial trypsinization corroborates our earlier observation that these EB binding proteins mediate attachment.

Glycogen accumulation in normal and irradiated minced muscle autografts on frog gastrocnemius

Alterations induced in glycogen content and phosphorylase activity have been studied in normal and irradiated minced muscle autografts on frog gastrocnemius at days 1, 3, 5, 7, 10, 15 and 30 postgrafting. The changes observed in the glycogen content and phosphorylase activity conform to the degeneration and regeneration phases of muscle repair. An attempt has been made to explain the altered glycogen utilizing capacities of the frog skeletal muscle during its repair and regeneration.

Endogenous 24-hour cycle of core temperature and oxygen consumption in week-old Zucker rat pups

Experiments were designed to test whether or not the 24-h core temperature fluctuations in week-old rat pups are of endogenous origin. Lean (Fa/-) Zucker rat pups born on the same day to mothers maintained in two different colonies with light/dark cycles 12 h out of phase with each other were mother-reared through the first 3-4 days of life and then artificially reared simultaneously in constant dim light. Continuous, automatic measurement of core temperature and oxygen consumption during artificial rearing showed clear 24-h rhythms in 5- to 8-day-old pups. Each rhythm reached a daily minimum at a time corresponding to the beginning of the light period in the colony of origin. The amplitude of these rhythms did not diminish during artificial rearing, nor did the phase difference between the rhythms of pups originating in the two colonies systematically change. The persistent 12-h phase differences between these two groups of pups prove that the observed rhythms are not caused by exogenous stimuli. We conclude that the rat pup possesses an endogenous time-keeping mechanism that permits the expression of overt rhythmicity at the age of 1 week.

Affinity chromatography on a hydrophobic matrix using a heterobifunctional ligand

Affinity adsorption chromatographic purification using heterobifunctional ligands and a hydrophobic support is described. Soybean trypsin inhibitor was modified with a detergent, with the result that hydrophobic residues were attached to the inhibitor. On passage through an octyl-Sepharose column the inhibitor was bound to the support. The modified inhibitor was still able to bind trypsin either in free solution or after the inhibitor was bound by the support. This procedure forms the basis for a robust affinity purification technique that can be made very general.

HLA-linked susceptibility to rheumatoid arthritis in north India

Nine multiplex RA families of North Indian origin were tissue typed to determine the segregation of parental haplotypes among sibs. The assortment of haplotypes in 18 affected sibs was not random, with seven sib pairs being HLA identical and two haploidentical with the proband (P = 0.0007). HLA-DR4 occurred in eight out of nine probands (88.8%) and in 11 out of 13 familial RA subjects (84.6%).

Cloning, expression, and primary structure of a Chlamydia trachomatis binding protein

The gene encoding an 18,000-dalton eucaryotic cell-binding protein of Chlamydia trachomatis serovar L2 was cloned into Escherichia coli, and the nucleotide sequence of a 1,658-base-pair PstI restriction endonuclease fragment encoding this protein was determined. The recombinant chlamydial gene consists of a 486-base-pair open reading frame encoding a polypeptide of molecular weight 18,314. The resultant polypeptide, comprising 162 amino acids, possesses a highly charged carboxy-terminal end. The expression of this recombinant protein is under the control of a vector promoter. The recombinant 18,000-dalton protein possessed the same eucaryotic cell-binding characteristics as did the native chlamydial 18,000-dalton protein when electrophoresed and transferred to nitrocellulose. Polyclonal antibodies to the recombinant protein exhibited neutralizing activity.

Dissociation between apparent volumes of distribution for inulin and sodium by salt adaptation in ducks

In domestic ducks acclimated to 2% saltwater (SW ducks), chronic elevations of plasma osmolality and sodium concentration, and of the circulating levels of antidiuretic hormone and angiotensin II indicate a trend towards dehydration when compared to ducks maintained on freshwater (FW ducks). Under steady state conditions of salt and water balance, with prevailing antidiuresis and no salt gland secretion, the apparent volumes of distribution of 22Na and of radiolabeled inulin were calculated after single injections of the tracers. The sodium spaces as percent body mass of FW ducks (33.3 +/- 0.9) and SW ducks (31.5 +/- 0.5) were not different, but apparent volumes for inulin distribution differed significantly between FW ducks (31.2 +/- 0.7) and SW ducks (24.8 +/- 0.7). Plasma volumes and rates of inulin disappearance from the plasma during both the non-uniform and uniform phases of tracer distribution were closely similar in FW and SW ducks and support the hypothesis that the difference between apparent volumes of inulin distribution reflects a difference in extracellular fluid volume which was estimated as 20.9% in FW ducks and 17.2% in SW ducks. For SW ducks the difference between inulin and sodium spaces was significantly greater than for FW ducks. In relation to the extracellular fluid compartment SW ducks have a larger pool of non-extracellular exchangeable sodium.

Thermoregulation and diurnal rhythms in 1-week-old rat pups

This paper reviews the ontogeny of thermoregulation and diurnal rhythmicity in rats. Additionally, original data are presented that indicate the emergence of an endogenous circadian core temperature rhythm during the first postnatal week. Despite neurological immaturity, newborn rats display autonomic and behavioral thermoregulatory responses within 24 h of birth. Their "biological clock" is already running before birth. The thermal environment of pups changes cyclically owing to diurnal variations in maternal behavior, but the core temperatures of 1-week-old pups huddling in the absence of the dam also show marked diurnal fluctuations. Five- to 8-day-old lean Zucker rat pups artificially reared in the absence of 24-h cycles of ambient temperature and food intake show diurnal changes in core temperature similar to those in huddling mother-reared pups. Diurnal core temperature changes, evident only when regulatory effectors are not overwhelmed, are one of the first self-maintained diurnal rhythms to appear. Because thermoregulation and circadian rhythmicity both appear before maturation of the neural networks believed to be critical for their control in adult animals, studying the immature rat might increase our understanding of the control of these processes in the more complex mature central nervous system.

Cyclic AMP inhibits developmental regulation of Chlamydia trachomatis

The effect of cyclic AMP (cAMP) on the chlamydial growth cycle was studied with Chlamydia trachomatis-infected HeLa cells. At concentrations of 1 mM, cAMP had a profound effect on the chlamydial developmental cycle, resulting in small, immature inclusions. Immunoblot analysis revealed the absence of elementary body (EB)-specific antigens in the cAMP-treated cells. This effect was observed only if cAMP was added within the first 12 h of incubation and continued thereafter. Its withdrawal at any time from the medium led to the reappearance of fully mature, infectious organisms. Analogs or breakdown products of cAMP exerted no inhibitory effect on chlamydial development. Intracellular inclusions from the cAMP-treated cells were unable to infect fresh HeLa monolayers, in contrast to the completely infectious nontreated inclusions. Protein profiles of the cAMP-treated organisms (at any time point) resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis very closely resembled reticulate bodies (RB) and did not possess characteristic EB-binding proteins. Collectively, these observations suggest an inhibitory role for cAMP at the RB stage of intracellular development. We also identified a cAMP receptor protein which is associated with RB and not with EB, further supporting a role for this system in the developmental regulation of chlamydiae.

Cold-rearing normalizes capacity for norepinephrine-stimulated thermogenesis but not body temperature in 16-day-old fatty Zucker rats

The effects of a lowered rearing temperature on body weight, core temperature (Tc) and norepinephrine(NE)-stimulated thermogenesis were investigated in 16- to 17-day-old Zucker rat pups. 16-day-old fatty pups were significantly heavier (9%) than lean littermates in litters reared at 18 degrees C ("cold-reared") but not in litters reared at 25 degrees C ("normally-reared"). After 2 h isolation at 25 degrees C, Tc of lean pups was slightly higher (37.1 degrees C) in cold-reared litters than in normally-reared litters (36.4 degrees C), while fatty pups reared at either temperature were severely hypothermic (Tc = 33 - 34 degrees C). At an ambient temperature of 25 degrees C Tc in fatty and lean cold-reared pups increased to 39.5 degrees C after subcutaneous injection of 800 micrograms/kg NE. Normally-reared lean pups reached the same peak Tc after NE injection, while their fatty littermates reached a significantly lower peak Tc of 38.4 degrees C. The hypothermia associated with the onset of excess fat deposition in suckling fatty Zucker rats is not caused by a reduced capacity for NE-stimulated thermogenesis.

Arginine vasotocin and glomerular filtration rate in saltwater-acclimated ducks

We examined the relationship between whole kidney glomerular filtration rate (GRF) and the plasma concentration of immunoreactive arginine vasotocin (AVT), the avian antidiuretic hormone, in saltwater-acclimated ducks. During steady-state diuresis, driven by infusion of sodium chloride solutions, transient reductions of [14C]inulin clearance (3 ml X min-1 X kg-1) occurred when plasma AVT concentrations were roughly doubled by systemic injection of synthetic AVT or after stimulation of endogenous AVT release by perfusion of the third ventricle with hypertonic artificial cerebrospinal fluid (CSF). Transient increases in GFR occurred when plasma AVT was reduced during inhibition of its endogenous release by hypotonic ventricle perfusion. GFR also increased after injection of AVT antiserum but returned to control values within 30 min, while plasma AVT concentration remained very low for at least 1 day. During antidiuresis evoked by infusion of strongly hypertonic saline, GFR values estimated from plasma disappearance curves of [125I]iothalamate were not different from the GFR values estimated subsequently with the same method in the same ducks made diuretic by hypotonic saline infusions, although AVT concentrations were depressed during the latter as compared with the former infusion. Factors other than AVT must be important for the control of GFR during sustained osmotic stress.

Maturation of thermoregulation in Zucker rats

We compared the development of thermoregulatory abilities of fatty (fa/fa) and lean (Fa/-) Zucker rats as they grew from two weeks to eight months of age. The rectal temperature of lightly restrained littermates was continuously recorded for 2-6 h, and at ages before body weights of fatty and lean pups became significantly different, oxygen consumption was simultaneously measured. At the rearing temperature of 25 degrees C, hypothermia with a 30 percent lower oxygen consumption was apparent in fatty pups at 16 but not at 24 days. At 5 degrees C on day 25 fatty pups became hypothermic with a metabolic rate only 10-15 percent lower than lean pups. Three-month old fatty and lean rats defended the same core temperature not only at 25 degrees C, but even during 6 h without food at 5 degrees C. The core temperature of 5-8 month old fatty rats fell slightly but significantly below that of lean rats only during the sixth hour at 25 degrees C, but not during 6 h at 5 degrees C. If the capacity for thermogenesis in brown adipose tissue of fatty rats is less than in lean rats, its decreased contribution to cold defense must be completely made up in 25 degrees C-acclimated adults by more insulation and/or shivering.

Isolation and characterization of human factor IX cDNA: identification of Taq I polymorphism and regional assignment

Hemophilia B or Christmas disease is an X-linked condition caused by absent or reduced levels of functional coagulation factor IX. Based upon the peptide sequence of bovine factor IX, we synthesized a 17-base pair oligonucleotide probe to screen a human liver cDNA library. A recombinant clone was identified with a 917-nucleotide insert whose sequence corresponds to 70% of the coding region of human factor IX. This factor IX cDNA was used to probe restriction endonuclease digested human DNA to identify a Taq I polymorphism associated with the genomic factor IX gene as well as to verify that there is a single copy of this gene per haploid genome. The factor IX cDNA was also used to map the locus for factor IX to a region from Xq26 to Xqter. The cloning of human factor IX cDNA and identification of a Taq I polymorphism and its regional localization will provide a means to study the molecular genetics of hemophilia B and permit linkage analysis with nearby loci.

Body temperature of huddling newborn Zucker rats

Daily mean core temperature (Tc) in huddling Zucker rat pups reared at 25 degrees C revealed the onset of a significantly lower Tc in fa/fa pups on day 6. The difference between any pup's Tc and the mean Tc of that half of the litter with the highest Tc on any given day was an early marker for genotype. Calculating the mean difference for any 2 consecutive days from day 6 onwards gave values for each fa/fa pup that were outside the 99% confidence limits for the individual observations in the Fa/- pups.

Combined modality therapy for Stage IIIMO non-small cell lung cancer. A five-year experience

Between 1975 and 1980, 101 patients with inoperable Stage IIIMO non-small cell lung carcinoma were entered into combined radiotherapy and chemotherapy trials at Michael Reese Hospital and University of Chicago Hospital. Sixty-four percent of the patients responded. Median survival for all patients was 8.8 months. Responders survived 13.7 months and nonresponders 4.6 months (P = 0.002). Patients treated with 4200 rad had a higher response rate than those treated with 3000 rad (74% versus 54%, P = 0.04) but there was no difference in survival. Although all patients with squamous cell carcinoma died by 30 months, 18% of patients with adenocarcinoma and 20% of patients with large cell carcinoma are long-term survivors. Brain metastases occurred more frequently in patients with large cell or adenocarcinoma than in patients with squamous cell carcinoma (P = 0.02). The prognostic effect of age, initial performance status, sex, histology, and tumor extent are examined. Toxicity was substantial with a 13% treatment-related mortality. Combined modality therapy may benefit selected patients with non-squamous cell types, but more effective chemotherapeutic agents are needed. Prophylactic cranial irradiation in patients with large cell carcinoma or adenocarcinoma may decrease the incidence of subsequent brain metastases.

Immobilization of fumarase by entrapment of rat liver mitochondria in polyacrylamide gel using gamma rays

A stable immobilized preparation of fumarase (EC 4.2.1.2) was obtained by entrapment of rat liver mitochondria in acrylamide polymerized by using gamma irradiation (100 kR). The enhanced stability and the efficiency of the entrapped enzyme have shown potential for repeated use for the production of L-malic acid from fumaric acid. The possible formation of succinic acid in the system could be controlled by incorporating malonate along with detergents such as sodium deoxycholate or sodium dodecylsulfate in the reactor system.

2-14C-1-Allyl-3,5-diethyl-6-chlorouracil I: Synthesis, absorption in human skin, excretion, distribution, and metabolism in rats and rabbits

With 14C-potassium cyanate as the starting material, 2-14C-1-allyl-3,5-diethyl-6-chlorouracil was synthesized for in vitro and in vivo absorption studies in human skin and for metabolic studies in rats and rabbits. The radioactivity in the horny layer, epidermis, and dermis of the human skin was determined after different intervals of time, and the radioactivity excreted in the urine was measured by collecting samples for 5 days from a patient and also under occlusion conditions. Almost 90% of the radioactivity remained on the surface and approximately 6.28% penetrated and was systemically absorbed. Over a 5-day period, a total of 3.25% was excreted. Almost 3% was systemically absorbed and cumulated in the system. After intraperitoneal application in male and female rats, most of the radioactivity was excreted in the feces and urine, with female rats excreting more in the urine than male rats. The radioactivity rose in the organs in the first 3 hr and then decreased. At the end of 144 hr, no appreciable radioactivity could be found in the organs and tissues, except in the carcass where the cumulation was maximum (1%). After intravenous injection in rabbits, most of the radioactivity (80%) was excreted in the urine and only 4% in the feces. At the end of 96 hr, approximately 3% was cumulated in the body. The drug was quantitatively metabolized in both rats and rabbits: Metabolite 1 (70-85%), Metabolite 2 (10-15%), Metabolite 3 (5-10%), and Metabolite 4 (0.3%).

2-14C-1-Allyl-3,5-diethyl-6-chlorouracil II: Isolation and structures of the major sulfur-free and three minor sulfur-containing metabolites and mechanism of biotransformation

The metabolites of 1-allyl-3,5-diethyl-6-chlorouracil in rabbit urine were isolated by preparative thick-layer, liquid-column, and gas chromatography. With the aid of mass and 1H-NMR spectra, and by comparison with an authentic sample, the major metabolite, 1, was identified as 6,8-diethyl-2-hydroxymethyl-tetrahydrooxazolo-[3,2-c]-pyrimidine-5,7(4H,6H)-dione, Metabolite 2 as 1-allyl-3-ethyl-5-(1-hydroxyethyl)-6-methylthiouracil, Metabolite 3 as 1-allyl-3,5-diethyl-6-methylthiouracil, and Metabolite 4 as 6,8-diethyl-2-hydroxymethyl-tetrahydrothiazolo-[3,2-c]pyrimidine-5,7(4H,6H)-dione. The mechanism of the formation of sulfur-containing metabolites is discussed, and a new metabolic pathway for the formation of methylthio compounds is proposed.