Inhibition of glycolysis in boar sperm by alpha-chlorohydrin

The effect of alpha-chlorohydrin (3-chloropropan-1,2-diol) on the metabolism of D-[U-14C]-fructose and L-[U-14C]-lactate by washed boar sperm has been investigated. Whereas alpha-chlorohydrin at concentrations as low as 0.1 mM inhibited the metabolism of fructose and led to an increase in the utilization of endogenous lactate, amounts up to 500 mM had no effect on the oxidation of added lactate. Low levels of alpha-chlorohydrin increased the cellular concentrations of fructose-1,6-bisphosphate and the triosephosphates, an effect consistent with the inhibition of glyceraldehyde-3-phosphate dehydrogenase. Although [U-14C]-glycerol was rapidly oxidized by boar sperm, [U-14C]-alpha-chlorohydrin was not metabolized to 14CO2, showing that it is not converted to glycerol. Extracts obtained by sonication of boar sperm after incubation with [3-36C1]-alpha-chlorohydrin, did not contain [3-36C1]-alpha-chlorohydrin-1-phosphate. This is contrary to the postulate that this phosphorylated compound is the inhibitory metabolite of alpha-chlorohydrin.

The fate of S-propylcysteine in the rat

1. The metabolism of S-propylcysteine in the rat has been re-investigated. The previously known major metabolite has been isolated and identified as the mercapturic acid, N-acetyl-S-propylcysteine. 2. Several further metabolites have been isolated from the urine of rats treated with S-propyl[35S]cysteine. These have been identified as S-propylcysteine-S-oxide, N-acetyl-S-(2-hydroxypropyl)cysteine, S-(propylthio)lactate, S-(2,3-dihydroxypropyl)cysteine and N-acetyl-S-(2-carboxyethyl)cysteine. 3. The metabolism of S-(2-hydroxypropyl)-, S-(3-hydroxypropyl)- and S-(2,3-dihydroxypropyl)-[35S]cysteine have been investigated in the rat. The results, integrated with those from the metabolism of S-propyl[35S]cysteine, have enabled the pathways of S-propylcysteine to be deduced. 4. The oxidative metabolism of a number of S-alkyl cysteines is discussed.

Blood donor protection

The quality of blood donated or purchased may be not only inferior from a recipient or user point of view, but donation may also be injurious to the health of the donor. A study of 1215 paid donors suggests that the current screening guidelines for all donors may not be adequate. More extensive haematological study of these donors shows that abnormalities of individual haematological parameters may range from 4.3% to as high as 29.5% deending on the donor population and the quality of the screening examination. The study concludes that the donor should be better protected.

Metabolism of three active analogues of the male antifertility agent alpha-chlorohydrin in the rat

1. Two ketal derivatives of alpha-chlorohydrin, which possess male antifertility activity, have been synthesized labelled with 36Cl. Both are metabolized by the rat to beta-chloroacetic acid. 2. Neither derivative inhibited the glycolytic enzymes glyceraldehyde 3-phosphate dehydrogenase and triosephosphate isomerase. 3. The epoxide glycidol is metabolized to beta-chlorolactic acid, presumably by first being converted to alpha-chlorohydrin. 4. It is proposed that the male antifertility actions of these three analogues is due to their biotransformation to alpha-chlorohydrin, which is then metabolized within mature sperm to a compound which is an inhibitor of glycolysis.

The oxidative metabolism of 1-bromopropane in the rat

1. The metabolism of 1-bromopropane in the rat has been re-investigated. The previously known metabolites have been isolated and confirmed as the three mercapturic acids N-acetyl-S-propyl cysteine, N-acetyl-S-propyl cysteine-S-oxide and N-acetyl-S-(2-hydroxypropyl)cysteine. 2. Three further metabolites have been isolated from the urine of rats treated with 4-bromopropane. These have been identified as 3-bromopropionic acid and the mercapturic acids N-acetyl-S-(3-hydroxypropyl)cysteine and N-acetyl-S-(2-carboxyethyl)cysteine. 3. The metabolites of 3-bromopropanol and 3-chloropropanol in the rat have been shown to be the mercapturic acids N-acetyl-S-(3-hydroxypropyl)cysteine and N-acetyl-S-(2-carboxyethyl)cysteine and the corresponding 2-carboxyethyl halide. 4. Studies with 1-bromopropane and the 3-halopropanols in vitro indicate that oxidation of C3 and C2 of 1-bromopropane occurs before conjugation of the alkyl group with glutathione. The implications of these studies are discussed in relation to the mechanism of the biosynthesis of the S-(2-hydroxyalkyl)mercapturic acid metabolites derived from the alkyl halides.

The metabolism of the soil fumigant 1,2-dibromo-3-chloropropane in the rat

The soil fumigant 1,2-dibromo-3-chloropropane (I) undergoes hydrolysis in the rat to a series of epoxide metabolites. Alkylation of glutathione by these epoxides produces 2 urinary metabolites identified as the mercapturic acids VI (R=COCH3) and VII (R-COCH3). Hydrolysis of the epoxides produces the male antifertility agents alpha-chlorohydrin (IX, X-Cl) and alpha-bromohydrin (IX, X-Br) which are oxidatively metabolized to oxalic acid (XII), thus causing renal damage. These metabolic pathways can explain the toxic nature of the fumigant as a carcinogen, a male chemosterilant and as an agent causing kidney damage.

Epoxides as obligatory intermediates in the metabolism of alpha-halohydrins

1. The metabolism of several dihalopropanols has been studied in the rat. Irrespective of their structure, each compound produced the same two mercapturic acids, excreted as urinary metabolites. 2. The mercapturic acid metabolites of the dihalopropanols were identified as N-acetyl-S-(2,3-dihydroxypropyl)cysteine and N,N'-bis-acetyl-S,S'-(1,3-bis-cysteinyl)propan-2-ol. Depending on the halogen present, each dihalopropanol produced beta-chlorolactate or beta-bromolactate as oxidative metabolites. 3. From the metabolic pathway of these compounds, it is inferred that an epoxide is an intermediate in their metabolism. 4. The metabolism of 2-chloropropane-1,3-diol has been investigated in the rat and the isolation of one mercapturic acid, N-acetyl-S-(2,3-dihydroxypropyl)cysteine, confirms that an epoxide intermediate is involved.

The metabolism of 3-amino-1-chloropropan-2-ol in relation to its antifertility activity in male rats

1. The metabolism of 3-amino[36Cl]chloropropan-2-ol (III) was studied in male rats. Three urinary metabolites were isolated and identified as alpha-chlorohydrin (I), beta-chlorolactic acid (V) and oxalic acid (VI). Much of the administered aminochloropropanol was excreted unchanged in the urine; 63% within 72 h, 75% over 250 h. 2. Monoamine oxidase is capable of converting aminochloropropanol to beta-chlorolactaldehyde (IV) which, by processes of either reduction or oxidation, suggests that the metabolic pathway is IV leads to I and IV leads to V leads to VI. 3. As assessed by the diuretic activities of the isomers of aminochloropropanol, oxalate appears to be produced by the (+)-isomer but not by the (-)-isomer. A difference in metabolic rate or route of the isomers may account for their differing physiological activities. 4. (+)- and (-)-aminochloropropanol exhibited identical in vitro inhibitory activities on the glycolytic enzymes glyceraldehyde-3-phosphate dehydrogenase and triosephosphate isomerase, and were substrates for monoamine oxidase to equivalent extents.

Effects of glycine administration on canine experimental spinal spasticity and the levels of glycine, glutamate, and aspartate in the lumbar spinal cord

Twelve female mongrel dogs were made paraplegic by midthoracic spinal cord transection. Beginning at 9 weeks posttransection, either glycine (50 mg/kg) or saline was injected intramuscularly each day and the signs of spinal spasticity were assessed clinically. After treating the dogs for 3 weeks, we removed the lumbar enlargement of each dog and microdissected it into gray and white areas which we assayed for glycine, glutamate, and aspartate content. Some of the clinical signs of spasticity improved in the animals injected with glycine compared to the saline-injected controls. The content of glycine was significantly elevated in the central gray matter and ventral medial white matter of the glycine-treated dogs. The levels of glutamate were also significantly elevated in the central, lateral ventral, and medial ventral gray matter and in the dorsal lateral and ventral medial white matter of the glycine-treated dogs. The possible role of these segmental putative neurotransmitters in spinal spasticity is discussed.

The antifertility action of alpha-chlorohydrin: enzyme inhibition by alpha-chlorohydrin phosphate

Preparations of the enzymes glyceraldehyde-3-phosphate dehydrogenase and triosephosphate isomerase are shown to be inhibited by alpha-chlorohydrin phosphate (II) in a competitive and non-competitive manner, respectively. alpha-Chlorohydrin (I), glycidol and epi-chlorohydrin have no inhibitory activities suggesting that their antifertility actions are due to their metabolism in vivo to alpha-chlorohydrin phosphate.

The oxidative metabolism of alpha-chlorohydrin in the male rat and the formation of spermatocoeles

1. The oxidative metabolism of [3-36C]chloropropan-1,2-diol (alpha-chlorohydrin, I) was studied in male rats. Two metabolites were isolated and identified as beta-chlorolactic acid (IV) and oxalic acid (V). 2. Neither alpha-chlorohydrin nor beta-chlorolactate was concentrated in any tissue. Traces of an intermediate metabolite, beta-chlorolactaldehyde (III) were detected in the urine within 4 h of administration. Studies in vitro indicated that the metabolic pathway is: alpha-chlorohydrin leads to beta-chlorolactaldehyde leads to beta-chlorolactic acid. 3. A comparative study of the metabolism of 36Cl- and 14C-beta-chlorolactate showed that oxalate was produced slowly and, as calcium oxalate, caused a type of renal glomerular nephritis. This pathological condition is responsible for the diuretic action of both alpha-chlorohydrin and beta-chlorolactate and, in higher doses, for their toxicities. 4. The role of oxalate, as a metabolite of alpha-chlorohydrin and of a number of related compounds, in inducing the formation of spermatocoeles in the male rat reproductive tract is discussed.

Alkylating esters. X. The reaction of some aziridine alkylating agents with methionine and S-methyl cysteine

Two biologically active aziridine ring-containing compounds, N,N-ethylene urethane (I) and N,N-ethylene urea (II), have been shown to react with methionine in dilute phosphate buffer (pH 7.4) at 37 degree C. Degradative procedures indicate that the aziridine ring effectively alylates the thio ether group of methionine and other thio ether-containing amino acids to produce sulphonium salts (V). By using [35S]methionine, the sulphonium salts have been shown to be quite stable under physiological conditions (t1/2 7--9 days) hydrolysing to convert the methionine residue to homoserine. It is proposed that similar alkylations of methionyl residues in vivo by aziridine-alkylating agents may explain the complex, and al yet unknwn, metabolic fate of the aziridine ring and could also be a factor contributing to the diverse effects that these agents have on living cells.

The oxidative metabolism of alpha-chlorohydrin and the chemical induction of spermatocoeles

alpha-Chlorohydrin (I) is oxidatively metabolized to beta-chlorolactic acid (III) and oxalic acid (IV). Deposition of calcium oxalate within the renal tubules is responsible for the toxic effects of alpha-chlorohydrin and a similar action on the epididymis or epididymal blood vessels could initiate the formation of spermatocoeles from this and other male antifertility agents.

Transformation of lymphocytes from patients awaiting cadaver renal transplants

The response of lymphocytes from prospective kidney transplant recipients to inactivated donor lymphocytes (one-way mixed-lymphocyte reaction (M.L.R.)) and to phytohaemagglutinin (P.H.A. response) was measured before transplantation of cadaver kidney allografts in 78 and 75 cases respectively. M.L.R. results from patients whose grafts had failed within 3 or 6 months compared with M.L.R. results from patients whose grafts continued to function at the same times showed only slight differences irrespective of whether the data was expressed as a relative response or a mitotic index. Because of the large overlap in values, it was concluded that the M.L.R. test was of limited value in predicting graft prognosis. Pretransplantation P.H.A. responses from patients whose grafts failed within 3 or 6 months were significantly different from those shown by patients whose grafts remained functioning at those times. It is suggested that lymphocyte responsiveness to P.H.A. before transplantation may be of value in predicting the fate of renal allografts.

A statistical technique for determining compliance with dual hygienic standards

A mathematical technique was developed to calculate log-normal distribution for sample results. This is then compared with a Limiting distribution defined by the sampling time, the Time-Weighted Average and the Ceiling Limit standard for the material tested. The technique provides a more effective means to decide if either or both the T.W.A. or Ceiling Limit has been exceeded. Sample times from 10 minutes to 4 hours are considered. A similar technique has previously been reported for evaluating benzene exposures. Examples are provided to illustrate the procedure.

The entry of alpha-chlorohydrin into body fluids of male rats and its effect upon the incorporation of glycerol into lipids

The rate of entry of alpha-chlorohydrin into rat rete testis fluid has been studied using the 14-C and 36-Cl-labelled compounds. The alpha-chlorohydrin crosses the blood-testis barrier and the concentration of radioactivity in rete testis fluid attained blood levels within 45 min. Within 3 hr of a single injection of [14-C] alpha-chlorohydrin, radioactivity was widely distributed in body fluids, and was present in the lipids of the brain, testis, epididymis and epididymal fat pads. No radioactivity was found in tissue lipids following the administration of [36-Cl] alpha-chlorohydrin, which suggests that dechlorination of this compound occurs before its incorporation. Neither a single high dose nor repeated low doses of alpha-chlorohydrin induced changes in the incorporation of [14-C] glycerol into lipids of the brain, testis, epididymis and epididymal fat pads.

The metabolism of 3-chloro,- 3-bromo- and 3-iodoprpan-1,2-diol in rats and mice

1. The metabolism of the 3-halopropan-1,2-diols (alpha-halohydrins) has been investigated in rats and mice. Apart from 3-chloropropan-1,2-diol (I), of which some 10% is excreted unchanged by both species, the compounds are completely degraded following intraperitoneal administration. 2. The alpha-halohydrins are detoxicated by conjugation with glutathione and produce two urinary metabolites, isolated and identified as S-(2,3-dihydroxypropyl)cysteine (VII) and the corresponding mercapturic acid N-acetyl-S-(2,3-dihydroxypropyl)cysteine (VIII). 3. When incubated with rat liver supernatant, the compounds do not conjugate with glutathione and their general chemical reactivity suggests that they react via a common intermediate proposed to be glycidol (2,3-epoxypropanol, IV). As the epoxide produces the same urinary metabolites as the alpha-halo-hydrins, and conjugates with glutathione either with or without liver supernatant to form the primary metabolite S-(2,3-dihydroxypropyl)glutathione (VI), glycidol is also proposed to be the reactive intermediate in vivo. 4. The role of epoxides in intermediary metabolism is discussed.