Disruption of the gene encoding subunit VI of yeast cytochrome bc1 complex causes respiratory deficiency of cells with reduced cytochrome c levels

A double mutant of Saccharomyces cerevisiae, in which CYCL gene is deleted and the chromosomal copy of the 17 kDa protein gene is disrupted, has been constructed. This mutant cannot grow on nonfermentable carbon sources, but normal growth can be restored by complementation of either mutation with a yeast vector containing either the wild-type 17 kDa protein gene or the CYCl gene. These results show that although the 17 kDa protein, subunit VI of yeast cytochrome bc1 complex is dispensable for yeast mitochondrial respiration in cells with the wild-type levels of cytochrome c, the 17 kDa protein is essential for respiration when the level of cytochrome c is limited, indicating that is plays a role in electron transport. This glycerol- phenotype of the double mutant can serve as the basis for further genetic studies on the function of the 17 kDa protein in yeast mitochondria and may provide insight into the physiological function of the hinge protein, the counterpart of the yeast 17 kDa protein, in beef heart mitochondria.

Voltage-dependent sodium channels in synaptoneurosomes: studies with 22Na+ influx and [3H]saxitoxin and [3H]batrachotoxinin-A 20-alpha-benzoate binding. Effects of proparacaine isothiocyanate

22Na+ influx and binding of [3H]saxitoxin ([3H]STX) and [3H]batrachotoxin-A 20-alpha-benzoate ([3H]BTX-B) were studied in guinea pig cerebral synaptoneurosomes. STX and tetrodotoxin (TTX) completely blocked the stimulation of sodium influx induced by 1 microM BTX. The IC50 values for STX and TTX closely matched the Ki values for inhibition of [3H]STX binding, suggesting that the sites labelled by [3H]STX are associated with a population of BTX-sensitive channels. BTX induced a dose-dependent stimulation of sodium influx in synaptoneurosomes (EC50 280 nM). The potency of BTX for stimulation of sodium influx was increased (EC50 24 nM) in the presence of 0.6 microgram/ml scorpion venom without any change in maximal influx. In contrast, specific binding of [3H]BTX-B to synaptoneurosomes was minimal in the absence of scorpion venom, but it was increased several fold in the presence of 60 micrograms/ml scorpion venom. With proparacaine isothiocyanate (PROPRIT), an irreversible local anesthetic, the inhibition of [3H]BTX-B binding by PROPRIT did not occur in parallel with an inhibition of sodium influx induced by BTX. Preincubation of synaptoneurosomes with 10 microM PROPRIT for 10 min resulted in approximately 70% inhibition of [3H]BTX-B binding in the presence of scorpion venom. Such preincubation did not alter BTX-induced sodium uptake in synaptoneurosomes. Preincubations of synaptoneurosomes with 100 microM PROPRIT for 10 min completely inhibited [3H]BTX-B binding, and under these conditions BTX-induced sodium influx was reduced only by 50%. The results indicate that virtual elimination of binding sites labeled by [3H]BTX-B in the presence of scorpion venom by PROPRIT has little effect on sodium influx induced by BTX.(ABSTRACT TRUNCATED AT 250 WORDS)

Recurrent benign esophageal strictures treated with self-bougienage: report of seven cases

Self-bougienage has rarely been used in the treatment of recurrent benign esophageal strictures. Nonetheless, it has proved to be a useful alternative technique in carefully selected patients. Herein we report our experience with seven symptomatic patients who were treated with self-bougienage for recurrent benign esophageal strictures. These seven patients (six men and one woman; mean age, 66.9 years) had had dysphagia for a mean of 37.9 months and had undergone a mean of 6.7 endoscopic dilations before their involvement in a self-bougienage program. During a mean follow-up period of 36.3 months (range, 10 to 78 months) after initiation of self-bougienage treatment, all seven patients became asymptomatic and remained free of dysphagia. No complications occurred in any patient, and no further endoscopic dilations were necessary. Our results suggest that self-bougienage can provide long-term symptomatic relief in selected patients with recurrent benign esophageal strictures.

Anti-opioid receptor antibody recognition of a binding site on brain and leukocyte opioid receptors

Opioid receptors reportedly exist on neuronal tissue of central and peripheral origin as well as on cells of the immune system. Previously, an opioid receptor has been purified from the neuroblastoma x glioma hybrid cell line, NG108-15 cells. In an effort to compare these results with opioid receptors isolated from primary neuronal tissue, we employed a methodology based on the molecular recognition theory to develop a monoclonal antibody which was used to isolate and biochemically characterize murine brain opioid receptors. We herein report the purification of an opioid receptor from mouse brain with a molecular weight of 65,000 daltons (range was 62-70 kD under reducing conditions) using a monoclonal antibody to an (the) opioid receptor. In situ labeling experiments with the delta-class selective opioid receptor affinity ligand, cis-(+)-3-methylfentanylisothiocyanate (SUPERFIT) of brain membrane confirmed these observations. Moreover, SUPERFIT, when coupled to the binding site, could block the recognition of the receptor by the monoclonal antibody. However, the selective, mu-class opioid receptor affinity reagent, 2-(p-ethoxybenzyl)-1-N,N-diethylaminoethyl-5-isothiocyanatobenz imidazole was ineffective at masking the binding site from recognition by the monoclonal antibody. Likewise, opioid-like receptors were purified from murine leukocytes which migrated at a molecular weight of 58,000 daltons under nonreducing conditions and 70,000 daltons under reducing conditions. In addition, immunoaffinity-purified receptor is shown to specifically bind the delta-class-selective opioid ligand, cis-(+)-3-methylfentanylisothiocyanate as well as the endogenous opioid peptides, beta-endorphin and [Met]-enkephalin.(ABSTRACT TRUNCATED AT 250 WORDS)

Gastroparesis after a presumed viral illness: clinical and laboratory features and natural history

Gastroparesis after a viral infection has rarely been reported. In this article, we describe the clinical features and long-term outcome of 7 patients who had gastroparesis after a presumed viral illness and who were identified in a retrospective review of 103 consecutive cases of gastroparesis seen at our institution from 1977 through 1988. The three male and four female patients with gastroparesis after a suspected viral illness were young (mean age, 26.9 years) and healthy before the onset of the illness, which manifested as low-grade fever, fatigue, and myalgia with or without diarrhea. A mean of 4.5 days after spontaneous resolution of the viral illness, persistent nausea, vomiting, and epigastric pain developed in these patients. In all seven patients, delayed emptying of the gastric contents was substantiated. Autonomic neuropathy was found in all three patients who underwent autonomic function tests. During a mean follow-up of 32.3 months, five of the seven patients had complete resolution of gastroparetic symptoms, and the other two had considerable improvement of their condition. We conclude that postviral gastroparesis is uncommon, is frequently associated with autonomic dysfunction, and is associated with an apparently excellent prognosis.

Cloning and expression of raw-starch-digesting alpha-amylase gene from Bacillus circulans F-2 in Escherichia coli

The raw potato-starch-digesting alpha-amylase gene of Bacillus circulans F-2 was cloned for the first time in Escherichia coli C600, using plasmid pYEJ001. The recombinant plasmid, named pYKA3, has a 5.4 kb insert from a chromosome of the donor bacterium. Subcloning of this amylase gene gave plasmid pHA300 which carried 3.15 kb of the inserted DNA. The transformed bacterium, E. coli C600 (pYKA3), produced the amylase in the periplasmic space, whereas it is secreted outside the cell in the donor bacterium. The cloned raw-starch-digesting alpha-amylase has a molecular weight of 93,000 on SDS-PAGE, and its action pattern was absolutely the same as that of the potent raw-starch-digestible amylase produced by B. circulans F-2. The periplasmic amylase produced by the transformed E. coli (pHA300) could digest raw starch granules such as potato, corn and barley raw starch granules, indicating that the raw-starch-digesting amylase is active in E. coli. Furthermore, this amylase crossreacted with the rabbit antiserum raised against the raw potato-digesting alpha-amylase of B. circulans F-2. From these results it was concluded that the cloned amylase is the same amylase protein as B. circulans F-2 amylase, which has a potent raw-starch digestibility. Thus, this paper is to our knowledge the first describing the molecular cloning of raw-starch-digesting alpha-amylase from Bacillus species and its successful expression in E. coli.

Procaine isothiocyanate: an irreversible inhibitor of the specific binding of [3H]batrachotoxinin-A benzoate to sodium channels

[3H]Batrachotoxinin-A benzoate ([3H]BTX-B) binds with high affinity to sites on voltage sensitive sodium channels in synaptoneurosomes from guinea pig cerebral cortex. Local anesthetics competitively antagonize the binding of [3H]BTX-B. An irreversible local anesthetic, procaine isothiocyanate (PRIT) and a tritiated derivative [( 3H]PRIT) have been prepared. PRIT inhibits the binding of [3H]BTX-B in a noncompetitive, irreversible manner (apparent Ki = 13 microM) whereas the parent compound, procaine, inhibits in a competitive, reversible manner (Ki = 40 microM). The dissociation rate of [3H]BTX-B from sites on the sodium channel is greatly accelerated in a concentration dependent manner in the presence of PRIT. A 50% increase in the dissociation rate of [3H]BTX-B is achieved in the presence of 0.98 microM PRIT. [3H]PRIT binds irreversibly to three proteins in synaptoneurosomes with apparent molecular weights of 20, 42, and 68 kDa. Protection studies with procaine and other local anesthetics suggest that only the 68 kDa species was related to local anesthetic binding.

The potent opioid agonist, (+)-cis-3-methylfentanyl binds pseudoirreversibly to the opioid receptor complex in vitro and in vivo: evidence for a novel mechanism of action

The present study demonstrates that pretreatment of rat brain membranes with (+)-cis-3-methylfentanyl [(+)-cis-MF], followed by extensive washing of the membranes, produces a wash-resistant decrease in the binding of [3H]-[D-ala2,D-leu5]enkephalin to the d binding site of the opioid receptor complex (delta cx binding site). Intravenous administration of (+)-cis-MF (50 micrograms/kg) to rats produced a pronounced catalepsy and also produced a wash-resistant masking of delta cx and mu binding sites in membranes prepared 120 min post-injection. Administration of 1 mg/kg i.v. of the opioid antagonist, 6-desoxy-6 beta-fluoronaltrexone (cycloFOXY), 100 min after the injection of (+)-cis-MF (20 min prior to the preparation of membranes) completely reversed the catatonia and restored masked delta cx binding sites to control levels. This was not observed with (+)-cycloFOXY. The implications of these and other findings for the mechanism of action of (+)-cis-MF and models of the opioid receptors are discussed.

Pulmonary diffuse alveolar septal amyloidosis--diagnosed by transbronchial lung biopsy

Diffuse alveolar septal involvement is a rare form of pulmonary amyloidosis. Antemortem diagnosis is unusual, and most of the reported cases were diagnosed at autopsy. It has recently been reported that transbronchial lung biopsy via a flexible fiberoptic bronchoscope was a relatively safe method to confirm diffuse alveolar septal amyloidosis. We report a case of pulmonary diffuse alveolar septal amyloidosis confirmed by transbronchial lung biopsy. The patient's chief complaints were dyspnea on exertion and epigastric pain aggravated over a one-year period, while a chest roentgenogram showed bilateral diffuse interstitial infiltration. This case also showed nephrotic syndrome, cardiac arrhythmia, congestive heart failure, a tingling sensation in both hands and multiple nodules in the gastrointestinal tracts, suggesting involvement of the kidney, heart, peripheral nerves and gastrointestinal tracts. We propose that when diffuse interstitial lung disease is present with systemic signs such as nephrotic syndrome or cardiac arrhythmia, amyloidosis should be considered as a possible diagnosis. Also, transbronchial lung biopsy may be a useful confirmative diagnostic tool.

A study of the interaction of the alkylating agent, NIH10236, with opioid receptors in vitro and in vivo

The series of experiments reported in this paper examined the spectrum of subtypes of opioid receptors alkylated in vitro by N-cyclopropylmethyl-7 alpha-methylfumaramido-6,14- endoethenotetrahydronororipavine (NIH10236) and four optical isomers of the methylfumaramidophenethyl derivatives of 3-methylfentanyl. Pretreatment of membranes with NIH10236 resulted in a wash-resistant inhibition of the binding of [3H]6 beta-fluoro-6-desoxyoxymorphone (mu binding sites), the binding of [3H][D-ala2,D-leu5]-enkephalin (both the higher and lower affinity delta binding sites) and was without effect on kappa binding sites labelled with [3H]bremazocine. All four potential alkylating derivatives of 3-methylfentanyl were inactive. Pretreatment of membranes with 1 microM of the reversible ligands, (+)-cis-3-methylfentanyl, but not its enantiomer, inhibited the binding of [3H]6 beta-fluoro-6-desoxyoxymorphone and the binding of [3H][D-ala2,D-leu5]enkephalin to the lower affinity binding sites by over 90%. This phenomenon is termed "pseudo-irreversible inhibition." Incubation of pretreated membranes for 60 min at 37 degrees C, in the presence of 200 mM NaCl and 50 microM GppNHp, only partially reversed the masking of opioid receptors by (+)-cis-3-methylfentanyl. For in vivo experiments, membranes were prepared 18-24 hr after the intracerebroventricular administration of 80 and 50 micrograms of NIH10236. This resulted in decreased labelling of mu binding sites, lower affinity [3H][D-ala2,D-leu5]enkephalin binding sites, as well as kappa binding sites, labelled by [3H]U69,593 and [3H]bremazocine. There was no apparent alteration in the higher affinity [3H][D-ala2,D-leu5]enkephalin binding site.(ABSTRACT TRUNCATED AT 250 WORDS)

Thermodynamic and spectroscopic characteristics of the cytochrome bc1 complex. Role of quinone in the behavior of cytochrome b562

Cytochrome b562 does not behave as a single independent thermodynamic component in preparations of purified quinol cytochrome c reductase. This effect is much more pronounced in quinone sufficient preparations; in such preparations, the epr spectrum of the cytochrome is Eh sensitive, with a peak shift from g = 3.42 to 3.48 occurring as the potential is lowered from 100 mV to 0 mV. The peak shift is dependent on the presence of quinone and can be restored to quinone-depleted preparations by supplementation with ubiquinol 2 if phospholipid depletion is not too severe. The results suggest that cytochrome b562 is strongly interacting with the Qc quinone binding site.

Electron transfer between liposomal cytochrome c1 and cytochrome c: catalytic implications of electrostatic potentials

Kinetics measurements of the electron transfer between ferricytochrome c and liposomal ferrocytochrome c1 (with and without the hinge protein) were performed. The observed rate constants(kobs) of electron transfer between liposomal ferrocytochrome c1 and ferricytochrome c at different ionic strengths were measured in cacodylate buffer, pH 7.4, at 2 C. The effect of ionic strength on the rate constant(kobs) of electron transfer between liposomal cytochrome c1 and cytochrome c is far greater than that in the solution kinetics (Kim, C.H., Balny, C. and King, T.E. (1987) J. Biol. Chem. 262, 8103-8108). The result demonstrates that the membrane bound cytochrome c1 creates a polyelectrolytic microenvironment which appears to be involved in the control of electron transfer and can be modulated by the ionic strength. The involvement of electrostatic potentials in the electron transfer between the membrane bound cytochrome c1 and cytochrome c is discussed in accord with the experimental results and a polyelectrolyte theory.

Exopolysaccharide-Deficient Mutants of Rhizobium fredii HH303 Which Are Symbiotically Effective

Nineteen Tn 5 -induced mutants of Rhizobium fredii HH303 defective in acidic exopolysaccharide synthesis were isolated by screening for lack of Calcofluor fluorescence. They were grouped by complementation analysis by using Rhizobium meliloti cosmids carrying exo genes. All of the 19 mutants were symbiotically effective or partially effective, indicating that the major bacterial acidic exopolysaccharide of this strain of R. fredii may not be required for symbiotic development in the soybean.

Opioid receptors on cells of the immune system: evidence for delta- and kappa-classes

Opioid peptides have been shown to modulate various parameters of both the humoral and cellular arms of the immune system. The modulatory capacity of the peptides can often be substantially reduced in the presence of naloxone, an opioid receptor antagonist, indicating a classical ligand-receptor interaction. In order to characterize these interactions further, we investigated the characteristics of opioid receptors on a macrophage cell line, P388d1. A delta-class opioid receptor was found with an Mr of 58,000. We also identified opioid receptors on MOLT-4 (T-cell) and IM-9 (B cell) cell lines as well as thymocytes and T cell-and B cell-enriched populations. Using the central (brain) kappa-selective agonist, U-69,593, it was also determined that P388d1 cells possess kappa-like opioid receptors. Scatchard analysis of the binding of [3H]U-69,593 revealed a single population of sites with a dissociation constant of 17 +/- 3 (S.E.M.) nmol/l and a total number of binding sites of 53.8 +/- 1.0 (S.E.M.) fmol/10(6) cells. Moreover, the racemic kappa-selective agonist U-50,488H was able to displace 50% of [3H]U-69,593 binding at 8.0 nmol/l, whereas other opioid ligands such as [Met]-enkephalinamide (delta-selective) and [D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin (mu-selective) were ineffective displacers of [3H]U-69,593 except at high concentrations.

myc-related proteins and DNA sequences in Trypanosoma brucei

The cAMP content of Trypanosoma brucei increases in parallel with ascending mammalian parasitemia to very high levels just before differentiation of the long-slender to the short-stumpy bloodstream form. Because expression of myc oncogenes is required for vertebrate cells to interpret proliferation signals and declines in response to cAMP mediated differentiation, we investigated whether T. brucei also harbored myc-like proteins and genes. Accordingly, we probed lysates of long-slenders, short-stumpies and procyclics (insect midgut stage) with antibody to myc proteins and also hybridized myc gene family sequences to procyclic DNA. We found that antibody to myc-family proteins of mammals reacts with 40 kDa and 55 kDa proteins in all three life cycle stages, and that procyclic DNA contains three EcoRI fragments that are homologous to a v-myc probe. One of these fragments also hybridizes to a synthetic 25-mer oligonucleotide deduced from a consensus sequence in the second exon of the myc family and expresses a 3.2 kb mRNA transcript in Northern blots of procyclic RNA. The conservation of myc-family homologous across the broad phylogenetic gap between mammals and trypanosomes illustrates ancient evolutionary relationships and raises the possibility of stage-specific expression of myc genes during the life cycle of T. brucei.

Probes for narcotic receptor mediated phenomena. 15. (3S,4S)-(+)-trans-3-methylfentanyl isothiocyanate, a potent site-directed acylating agent for the delta opioid receptors in vitro

Recently we reported the synthesis of the first enantiomeric pair of irreversible opioid ligands [(3S,4R)-(-)- and (3R,4S)-(+)-cis-4, SUPERFIT] and specific interaction of the latter with the delta receptor. Here we report another enantiomeric pair of irreversible opioid ligands, (+)-trans- and (-)-trans-3-methylfentanyl isothiocyanates [(3S,4S)-(+)-trans- and (3R,4R)-(-)-trans-4]. A single-crystal X-ray analysis of the 2,4,6-trinitrobenzenesulfonic acid salt of (+)-trans-3-methyl-N-phenyl-4-piperidinamine [(+)-trans-8] revealed it (and, therefore, 4) to have the trans configuration and the absolute configuration of (+)-trans-8 to be 3S,4S. The (+)-trans enantiomer of 4 was shown to be highly potent and about 10-fold more selective as an acylating agent than (-)-trans-4 for the higher affinity [3H]DADL (delta) binding site in rat brain membranes. In that assay, (+)-trans-4 and (+)-cis-4 were essentially equipotent as affinity ligands, and the levo enantiomers were considerably less potent. (+)-trans-4 was, thus, a potent, subtype-selective acylating agent for the delta opioid receptor in vitro. With membranes from NG108-15 neuroblastoma x glioma hybrid cells, containing only delta receptors, (+)-cis-4 was found to be a little more potent than (+)-trans-4. Similarly, (+)-cis-4 is the most effective inhibitor of adenylate cyclase in these membranes, (+)-trans-4 has weak activity, and the levo enantiomers are inactive. Only (+)-cis-4 was found to have antinociceptive activity in vivo.

Effect of the hinge protein on the heme iron site of cytochrome c1

X-ray absorption spectroscopic (XAS) studies on cytochrome C1 from beef heart mitochondria were conducted to identify the effect of the hinge protein [Kim, C.H., & King, T.E. (1983) J. Biol. Chem. 258, 13543-13551] on the structure of the heme site in cytochrome c1. A comparison of XAS data of highly purified "one-band" and "two-band" cytochrome c1 [Kim, C.H., & King, T.E. (1987) Biochemistry 26, 1955-1961] demonstrates that the hinge protein exerts a rather pronounced effect on the heme environment of the cytochrome c1: a conformational change occurs within a radius of approximately 5 A from the heme iron in cytochrome c1 when the hinge protein is bound to cytochrome c1. This result may be correlated with the previous observations that the structure and reactivity of cytochrome c1 are affected by the hinge protein [Kim, C.H., & King, T.E. (1987) Biochemistry 26, 1955-1961; Kim, C.H., Balny, C., & King, T.E. (1987) J. Biol. Chem. 262, 8103-8108].

Floxuridine-induced sclerosing cholangitis: an ischemic cholangiopathy?

A 43-year-old man underwent abdominoperineal resection of a rectal adenocarcinoma, and left hepatic lobectomy for a single metastasis. He then received hepatic artery infusions of floxuridine. The tumor did not recur, but sclerosing cholangitis and liver failure developed which necessitated orthotopic liver transplantation. In the hilus of the native liver, obstructive arteriopathy and portal venopathy were found. These lesions probably had been caused by drug-induced intravascular thrombosis. Thus, the sclerosing cholangitis that develops in many patients after floxuridine infusion may be ischemic rather than toxic. The patient described here is well, 14 months after orthotopic liver transplantation. Therefore, in some cases of floxuridine-induced cholangitis, liver transplantation appears to be indicated despite a history of metastasizing carcinoma.

Effect of inhibition of prostaglandin synthesis on epinephrine-induced gastroduodenal electromechanical changes in humans

We conducted a double-blind randomized study to investigate the role of endogenous prostaglandins in epinephrine-induced changes in human gastric electromechanical activity. Intravenous administration of a pharmacologic dosage of epinephrine (222 ng/kg per min) caused gastric dysrhythmia in 8 of 12 healthy subjects. After indomethacin treatment, the incidence of epinephrine-induced gastric dysrhythmia was reduced to 4 of 12 healthy subjects, which is similar to the incidence of gastric dysrhythmia noted in the placebo group. The difference, however, was not statistically significant (P = 0.2). Epinephrine also substantially inhibited both the amplitude and the frequency of antral contractions. Indomethacin treatment partially reversed the reduction in the amplitude but not the frequency of antral contractions. These results suggest that endogenous prostaglandins may, in part, regulate the amplitude of human antral contractions; however, the role of prostaglandins in epinephrine-induced gastric dysrhythmia in humans remains uncertain.

Korean version of the Geriatric Social Readjustment Questionnaire: cross-cultural comparison between Koreans and Americans in the perception of life events

The purpose of this study was to construct a Korean version of the Geriatric Social Readjustment Questionnaire (K-GSRQ), to investigate its applicability to the elderly and to compare cross-cultural differences in the perception of the life events between Koreans and Americans. The K-GSRQ consists of 33 items. Most of the life events considered as crucial in old age were similar in ranking in comparison between Koreans and Americans. Some differences in ranking can be attributed to the differences in Socio-cultural backgrounds. The K-GSRQ was applied to controls, neurotic cases and cases with physical illnesses. The result suggest that the Korean version of the Geriatric Social Readjustment Questionnaire is applicable for the study of the health status of the elderly in Korea.

Idiopathic cyclic nausea and vomiting--a disorder of gastrointestinal motility?

Eight patients (five men and three women) with previously unexplained recurrent cyclic episodes of nausea and vomiting are described. In these patients, the symptoms developed a mean of once every 3.2 months and persisted a mean of 3.5 days. None of the patients had an identifiable cause of their symptoms on conventional diagnostic tests. A detailed investigation of the gastrointestinal motility during an asymptomatic period revealed abnormal findings in all eight patients. Gastric hypomotility was substantiated in five patients, small bowel dysmotility in six, delayed gastric emptying in two, and gastric dysrhythmia in two. The data demonstrate that abnormal gastrointestinal motility occurs during an asymptomatic state in patients with cyclic episodes of nausea and vomiting. Because all patients with this syndrome had abnormal gastrointestinal motility but normal results of other gastrointestinal studies, idiopathic cyclic nausea and vomiting may be related to altered gastrointestinal motility.

Deterioration of membrane morphology, phospholipids, and cytoskeletal protein in rat erythrocytes exposed to tert-butyl hydroperoxide: protection by exogenous glutathione fails in selenium deficiency

Here we report scanning electron microscopy, phospholipid and fatty acid composition and cytoskeleton proteins of erythrocytes from Se-adequate and Se-deficient rats, showing protection by glutathione (GSH) against tert-butyl hydroperoxide (t-BuOOH)-induced hemolysis of erythrocytes from Se-adequate, but not from Se-deficient rats. Without exogenous GSH, erythrocytes incubated with t-BuOOH exhibited remarkable deterioration of cell membranes with diminished membrane phosphatidyl-ethanolamine, -serine, and -inositol and selective loss of a cytoskeletal protein, ankyrin 2-1. Without exogenous GSH these changes occurred in erythrocytes from both Se-deficient and Se-adequate rats. Dietary Se, through provision of glutathione peroxidase (GSH-Px) in erythrocytes as a probable scavenger of t-BuOOH, protects against hemolysis when GSH is available.