Occupational asthma due to deer dander

BACKGROUND

The literature on allergy to deer is limited. The allergenic component remains to be identified.

METHODS

We report a case of occupational asthma and rhinitis caused by deer dander. A 44-year-old male farmer had raised three red deer on his farm for 2 years, prior to occurrence of asthmatic symptoms. Dander extract was prepared from the patient's deer.

RESULTS

Skin-prick test elicited positive reactions to dander extracts from goat, sheep, camel, and cow as well as to deer dander extract. Bronchoprovocation test with deer dander extract elicited an early asthmatic response. Serum-specific IgE antibody to the deer dander extract was detected by enzyme-linked immunosorbent assay (ELISA). Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblot analysis showed five IgE binding components (110, 72, 59, 45, and 21 kilodalton) within the deer dander extract.

CONCLUSIONS

These results suggest that deer dander can induce occupational asthma through an IgE-mediated mechanism in a farmer raising deer.

Attenuation of p47phox and p67phox membrane translocation as the inhibitory mechanism of S-nitrosothiol on the respiratory burst oxidase in human neutrophils

The effect of the S-nitrosothiol (RSNO) on the activation of NADPH oxidase in human neutrophils was studied using an in vitro translocation system in which an anionic amphiphil, such as sodium dodecyl sulfate or arachidonate, plays a role as an activator. When membranes pretreated with RSNO and a cytosol fraction from resting neutrophils were combined to reconstitute the NADPH oxidase, both translocation of the cytosolic NADPH oxidase components such as p47phox and p67phox to the plasma membrane fraction and subsequent superoxide generation was inhibited. However, RSNO had no effect on O2- production when added after enzyme activation. A similar inhibition of translocation of recombinant p47phox was observed with RSNO-treated membrane. When the RSNO-treated membrane fraction was exposed to 2-mercaptoethanol the inhibition was reversed. The data suggest that RSNO inhibits translocation of p47phox or p47phox containing cytosolic complex via a direct effect on the membrane component of the NADPH oxidase.

A hospital-based, case-control study of risk factors for hemorrhagic fever with renal syndrome in soldiers of the armed forces of the Republic of Korea

A hospital-based, case-control study was conducted to measure risk factors for hemorrhagic fever with renal syndrome in Korean soldiers. Between October 1989 and January 1992, 196 cases and 295 controls were admitted into the study. Information was collected on behavioral and environmental variables, and the data were analyzed by multiple logistic regression. The strongest risk factors were seeing Apodemus in the area (odds ratio [OR] = 4.9), living in a primitive dwelling such as a lean-to (OR = 3.9), and being exposed to dust (OR = 3.7). The most protective factors were living in barracks (OR = 0.3-0.5) and self-reported use of any insecticide or insect repellent (OR = 0.5).

Glycosylation of lipoprotein lipase in human subcutaneous lipomas

Glycosylation of lipoprotein lipase (LPL) was studied in human subcutaneous lipomas. Heparin-releasable LPL activities were higher in lipomas than those in adjacent normal adipose tissues, and showed good correlation with cellular LPL protein mass. Molecular weight of LPL subunit was 57 kDa in both tissues. After endoglycosidase H-digestion, two types of LPL subunits were found in normal adipose tissues; partially sensitive (55 kDa) and totally sensitive (52 kDa) form. In lipoma tissues, the fraction of partially sensitive form (55 kDa) was increased comparing with control adipose tissues. These results suggest that partially sensitive subunits constitute the major secretable form of LPL in human subcutaneous lipomas.

Cell-free activation of the respiratory burst oxidase by protein kinase C

In intact neutrophils, phorbol ester treatment activates the respiratory burst oxidase, the enzyme responsible for O2-production by phagocytes. This effect is thought to be dependent on protein kinase C and on the phosphorylation of p47phox. In this paper, we report that protein kinase C activates the respiratory burst oxidase in a cell-free system consisting of isolated neutrophil cytosol and membrane. Oxidase activation required a highly active protein kinase C, recombinant p47phow and ATP, and was inhibited by the protein kinase C inhibitors H-7 and GF-109203X. PERIl depletion of cytosolic ATP by dialysis reduced oxidase activation by over 50% In contrast, neither protein kinase C inhibitors nor ATP depletion affected oxidase activation by SDS. These findings strongly suggest that in the cell-free system, the oxidase can be activated by the phosphorylation of p47phox.

[Effect of sodium nitrite on Trichomonas vaginalis]

We have investigated the action of sodium nitrite on the growth and morphologic changes of T. vaginalis and on the treatment of subcutaneous abscess by trichomonad in mice. Sodium nitrite inhibited the growth of metronidazole-sensitive KT9 isolate and metronidazole-resistant CDC85 strain of T. vaginalis as concentration of 6 mM and 10 mM, respectively. Intraperitoneal injection of sodium nitrite (70 micrograms, 100 micrograms, 130 micrograms/g body weight) did not reduce the size of abscess produced by subcutaneous inoculation of T. vaginalis in mice. T. vaginalis, treated with sodium nitrite at concentration giving about 50% inhibition of growth, showed fissures, many vacuoles and electron-translucent zone in the cytoplasm by transmission electron microscopy. In the case of CDC85 treated with 9 mM sodium nitrite, hydrogenosomal matrical change, destruction of hydrogenosomal membrane, autophagic vacuoles, disappearance of Golgi complex and polysome were notably observed. With above results, it is assumed that sodium nitrite inhibits the growth of metronidazole-sensitive and--resistant strains of T. vaginalis and induces the morphological changes of T. vaginalis although it does not affect in reducing of abscess size by T. vaginalis in mice.

Translocation of recombinant p47phox cytosolic component of the phagocyte oxidase by in vitro phosphorylation

Activation of superoxide-generating NADPH oxidase system of human neutrophils involves phosphorylation-dependent translocation of p47phox and other cytosolic components to the plasma membrane. In contrast to the stimulation of the NADPH oxidase in intact cells, however, the activation of cell-free system requires the addition of anionic amphiphiles such as sodium dodecyl sulfate (SDS) and arachidonate. In this system, translocation of p47phox is also an essential step for activation, but phosphorylation is not required. The basis of this difference in oxidase activation is not yet clear. We now report that in a cell-free oxidase system, phosphorylated recombinant p47phox can be translocated to the membrane in the absence of SDS or arachidonate. These findings suggest that both phosphorylation and SDS could cause a common change in conformation or charge of p47phox that may result in the association of p47phox with the plasma membrane.

Identification of CD44 splice variant in Korean colorectal cancers and cell lines

CD44 is a glycoprotein expressed in a wide variety of cell types. Recently expression of some alternatively-spliced variants of CD44 transcripts (CD44v) has been suggested to play a potential role in tumor metastasis and the detection of CD44v containing exon 6 to 11 may be helpful for the diagnosis of cancers. Expressions of CD44v containing exon 6 to 11 were investigated in 20 human colorectal cancer samples, peripheral blood leukocytes isolated from colorectal cancer patients, and 4 colorectal cancer cell lines using reverse transcription-polymerase chain reaction and Southern blot analysis. The standard form of CD44 transcripts was expressed in all samples tested. CD44v containing exon 6 to 11 was expressed in 18 cases of colorectal cancers (sensitivity = 90%), 3 out of 4 cell lines, and one normal tissue (specificity = 95%). These results suggest that the expression of CD44v containing exon 6 to 11 can be regarded as tumor specific and that this marker may be helpful for the early diagnosis of colon cancers, if specimens from the early stage are available.

Protective mechanism of glucose against alloxan-induced pancreatic beta-cell damage

Glucose prevented the alloxan- or H2O2-induced inhibition of insulin secretion in rat pancreatic islets. Hydrogen peroxide was detected during the incubation of islets with alloxan, and this generation of hydrogen peroxide was not affected by glucose. Treatment of beta-cells with alloxan or H2O2 caused elevation of cytosolic free Ca2+ and decrease of cellular NAD+. Glucose blocked the decrease of cellular NAD+ level, but did not abolish the increase of cytosolic Ca2+. These results indicate that glucose protected pancreatic beta-cell damage after the H2O2 generation and Ca2+ influx on a chain of reactions in the diabetogenesis of alloxan.

Effects of autologous sera on immediate and late skin reaction to the house dust mite in atopic individuals

To evaluate the in vivo effect of autologous serum including antibodies to house dust mite in atopic individuals, we observed the immediate (15 mins) and late (6 hours) skin reactions (ISR, LSR) on intradermal (ID) test of serially diluted Dermatophagoides farinae antigens (DFa, Allergopharma, Germany) mixed with autologous sera (DFa-S) and diluent alone (DFa-D). We tested 34 DFa-skin reactive atopic individuals including 12 asthmatics (BA), 8 asthmatics on immunotherapy with DFa (IT), and 14 healthy atopic controls (AC). We observed complete inhibition of ISR in the lowest allergen dose of DFa-S in 7 (58.3%) of 12 BA, 3 (37.5%) of 8 IT, and 2 (14.3%) of 14 AC. In BA, the inhibition of ISR was more frequent than AC (p < 0.05). We observed larger late reactions in half of LSR positive cases on ID test by DFa-S than by DFa-D (> or = 1.5 X size; accentuation of LSR). Accentuation of LSR were shown more frequently by DFa mixed with larger amount of serum (25% in 1:1 mix; 80% in 1:3 mix, p < 0.05). But there were no differences of DFa-specific IgE and IgG subclass antibodies regardless of the inhibition of ISR or the accentuation of LSR. In conclusion, some autologous sera from DFa-sensitive individuals showed the inhibition of ISR and the accentuation of LSR on DFa-ID test.

Regression of transplant coronary artery disease during chronic HELP therapy: a case study

This report concerns a heart transplant patient with hypercholesterolemia who showed rapid development of a severe transplant coronary artery disease. The patient received 10 mg pravastatine per day. Quantitative coronary angiography analyses of 4 serial angiograms clearly demonstrated that in the first 2.5 years following surgery, there was a rapid simultaneous progression in both the transplant coronary disease, involving the entire coronary system, and the development of segmental stenotic lesions. During one year of weekly heparin-mediated extracorporeal LDL-cholesterol precipitation (HELP) therapy in addition to diet and pravastatine therapy, the serum low density lipoprotein (LDL), lipoprotein (a) (Lp(a)), and fibrinogen levels could be reduced from 185 +/- 45 mg/dl, 138 mg/dl and 248 mg/dl, respectively, to interval values of 136 +/- 17 mg/dl, 48 +/- 15 mg/dl, and 185 +/- 44 mg/dl, respectively [interval value = (the concentration after HELP + the concentration before the next HELP treatment):2]. This therapy halted further progression of coronary diameter throughout the whole coronary system and brought about marked regression of segmental obstructive lesions.

Lipid peroxidation products mediate damage of superoxide dismutase

Membrane lipid peroxidation processes yield products that may react with superoxide dismutase (SOD), one of the key antioxidant enzymes against oxidative stress, resulting in oxidative modifications. We have investigated this possibility and have found that three types of SOD--CuZnSOD, MnSOD, and FeSOD--exposed to autoxidized linolenate in the presence of Fe3+ caused the loss of dismutase activity, fragmentation of peptides, and an increase in protein oxidation. Lysates from E. coli oxyR strains treated with tert-butyl hydroperoxide, which presumably induces lipid peroxidation, resulted in the activation of SOD. The lipid peroxidation-mediated damage to SOD may result in the perturbation of cellular antioxidant defense mechanisms and subsequently lead to a pro-oxidant condition.

Systemic plasmacytosis: a case which improved with melphalan

Plasmacytosis, a distinctive proliferative disorder of plasma cells, is characterized by peculiar multiple skin eruptions, lymphadenopathy and polyclonal hypergammaglobulinemia. To date there has been no report of such cases showing remarkable responses to therapeutic agents. We herein report a case of plasmacytosis which developed in a 52-year-old Korean man and showed remarkable improvement with melphalan.

Development of anti-p185HER2 immunoliposomes for cancer therapy

The product of the HER2 protooncogene, p185HER2, represents an attractive target for cancer immunotherapies. We have prepared anti-p185HER2 immunoliposomes in which Fab' fragments of a humanized anti-p185HER2 monoclonal antibody with antiproliferative properties (rhuMAb-HER2) were conjugated to either conventional or sterically stabilized liposomes. These immunoliposomes bind specifically to p185HER2-overexpressing breast cancer cells (SK-BR-3 and BT-474). High-affinity binding of anti-p185HER2 immunoliposomes is comparable to that of free rhuMAbHER2-Fab' or the intact antibody. Empty immunoliposomes inhibit the culture growth of p185HER2-overexpressing breast cancer cells, and this antiproliferative effect is superior to that of free rhuMAbHER2-Fab', indicating that liposomal anchoring of these anti-p185HER2 Fab' fragments enhances their biological activity. Efficient internalization of anti-p185HER2 immunoliposomes, demonstrated by light and electron microscopy, occurs by receptor-mediated endocytosis via the coated pit pathway and also possibly by membrane fusion. Doxorubicin-loaded anti-p185HER2 immunoliposomes are markedly and specifically cytotoxic against p185HER2-overexpressing tumor cells in vitro. Anti-p185HER2 immunoliposomes administered in vivo in Scid mice bearing human breast tumor (BT-474) xenografts can deliver doxorubicin to tumors. These results indicate that anti-p185HER2 immunoliposomes are a promising therapeutic vehicle for the treatment of p185HER2-overexpressing human cancers.

Glycosylation, dimerization, and heparin affinity of lipoprotein lipase in 3T3-L1 adipocytes

The relationship between glycosylation, dimerization, and heparin affinity of lipoprotein lipase (LPL) was studied in 3T3-L1 adipocytes. Three forms of LPL subunits were found in normal cells; totally endo H-resistant (57 kDa), partially sensitive (54 kDa), and totally sensitive (51 kDa) forms. LPL in normal cells was active, dimeric, and showed high affinity for heparin. LPL in cells treated with tunicamycin, preventing the transfer of N-linked oligosaccharide chain, was unglycosylated (51 kDa) and inactive. LPL proteins were found as an aggregate, and had low affinity for heparin. After treatment with castanospermine, an inhibitor of ER glucosidase I, 80% of LPL activity was inhibited. Most of LPL proteins were totally endo H-sensitive, present as an aggregate, and had low affinity for heparin. LPL in cells treated with deoxymannojirimycin, an inhibitor of Golgi mannosidase I, was active, dimeric, and had high affinity for heparin as in normal cells. But LPL subunits were all endo H-sensitive. These results suggest that core glycosylation and subsequent removal of glucose residue is required, but processing after Golgi mannosidase I is not necessary for dimerization and acquisition of high heparin affinity of LPL.

A case of adult-onset Bartter's syndrome

Bartter's Syndrome is characterized by renal potassium wasting with hypokalemia, metabolic alkalosis, increased renin-angiotensin-aldosterone system, normal blood pressure, resistance to the pressor effects of angiotensin II and juxtaglomerular cell hyperplasia. Most of the cases have been noted in the pediatric age group and adult-onset cases are very rare. We report a case of adult-onset Bartter's syndrome.

Assay of ornithine aminotransferase with ninhydrin

We developed an assay system for ornithine aminotransferase (EC 2.6.1.13) using ninhydrin. Pyrroline 5-carboxylate, a product of enzymatic transamination, reacts with ninhydrin under hot acidic conditions to form a reddish pigment soluble in ethanol. The millimolar extinction coefficient of reaction product dissolved in ethanol was 16.5 at 510 nm. Acidification with perchloric acid effectively abolished the interfering color development by L-ornithine and L-glutamate. The paired activity measurement in mouse tissues by ninhydrin and o-aminobenzaldehyde methods showed a good correlation (gamma = 0.985). In our ninhydrin method, stable ninhydrin replaced unstable o-aminobenzaldehyde, and sensitivity was much higher than that with the conventional o-aminobenzaldehyde method.

Measurement of IgE and IgG subclass antibodies to whole body antigen and two major allergens (Der fI & Der fII) of Dermatophagoides farinae in normal subjects and asthmatics

House dust mites have been known as the most important allergen in respiratory allergic diseases. Among several mite allergens, group I and group II antigens were recognized as major allergens. We measured specific IgE and IgG subclass antibodies against whole body antigen (WBA) and two major allergens of Dermatophagoides farinae (Der fI and Der fII) in sera from 66 adults with asthma (asthma group) and 34 normal subjects (healthy group) by ELISA. The mean O.D. values of WBA-specific IgE and IgG subclass antibodies in 100 studied sera were significantly higher than those of the two major allergens (p < 0.001) and the level of Der fII- IgG1, IgG4 and IgE were higher than those of Der fI but IgG2 of Der fI was higher than that of Der fII (p < 0.001). The level of IgG4 of WBA were significantly higher in the atopic group than in the nonatopic group (1.280 +/- 0.634 v.s. 0.8290 +/- 0.388, p < 0.001), but the WBA- IgG1, IgG2, IgG3 were not different between the two groups. Among IgG subclass antibodies of Der fI, IgG2 was significantly higher in the nonatopic group than in the atopic group (1.7770 +/- 0.255 v.s. 1.636 +/- 0.390, p < 0.05) but there were no differences in IgG1, IgG3, and IgG4. Among IgG subclass antibodies of Der fII, IgG2 (1.534 +/- 0.380 v.s. 1.3010 +/- .431, p < 0.05) and IgG4 (1.09650 +/- .567 v.s. 0.708 +/- 0.146, p < 0.001) were significantly higher in the atopic group than in the nonatopic group. IgE antibodies to WBA, Der fI and Der fII were significantly higher in the atopic group (p < 0.001). There were significant correlationships between the levels of IgE and IgG4 of WBA (r = 0.60), Der fI (r = 0.33) and Der fII (r = 0.72). Even though there were no differences in the levels of allergen specific IgE and IgG subclass antibodies between nonatopic healthy and nonatopic asthmatic groups, the number of sera with prominent level of IgG2 of WBA were more common in the nonatopic asthmatic group (69% in nonatopic asthma group v.s. 28% in nonatopic healthy group, X2-test, p < 0.01).(ABSTRACT TRUNCATED AT 400 WORDS)

Gene cloning of the human cytomegalovirus (HCMV) antigen reactive with the serum from a HCMV-infected patient

The human cytomegalovirus(HCMV) gene encoding the protein reactive with the sera of HCMV-infected patient was cloned and characterized. A reactive phage clone was screened from a lambda gt11 expression library of cDNA of HCMV AD169 strain using HCMV-infected patient sera. The recombinant protein was expressed as 138 kDa-fusion protein with beta-galactosidase, which was reactive with IgM or IgG HCMV antibody-positive sera, but not with anti-HCMV antibody-negative sera. A homology search of the DNA sequence of the cloned gene with HCMV AD169 sequences revealed that it was composed of 709 base pairs spanning between 0.174 and 0.177 map units of the UL32 region of the HCMV AD169 strain genome. This position corresponded to a part of the gene encoding 150 kDa phosphoprotein-(pp150), a major tegument protein, which was reported as an immunogenic protein which evoked strong and longstanding antibody response and had no sequence homology with the proteins of other herpesviruses. These results suggested that pp150 was an immunogenic protein in natural HCMV infection and therefore this clone was regarded as a useful candidate for developing an antigen for the serodiagnosis of HCMV.

Role of Ca2+ in alloxan-induced pancreatic beta-cell damage

Pretreatment of rats with verapamil, a Ca(2+)-antagonist, completely prevented alloxan-induced hyperglycemia. Verapamil also abolished the inhibition of insulin secretion by alloxan and H2O2 in isolated rat pancreatic islets. H2O2 generation from alloxan was not affected by verapamil, but alloxan- and H2O2-induced DNA strand breaks were completely prevented. Treatment of beta-cells with alloxan and H2O2 caused elevation of cytosolic free Ca2+, and this increase of Ca2+ was also abolished by verapamil. These results suggest that alloxan-derived oxygen radicals may disturb intracellular Ca2+ homeostasis by increasing Ca2+ influx, which results in secondary reactions ultimately leading to DNA strand breaks and cytotoxicity of beta-cells.

Inhibitory mechanism of Ca2+ on the hemolysis caused by Vibrio vulnificus cytolysin

Calcium in millimolar concentrations protected mouse erythrocytes from hemolysis caused by Vibrio vulnificus cytolysin without affecting the release of intracellular K+ from the cells. This effect was maximal at 25 mM CaCl2. The protection was not absolute and could be partially overcome by increased concentrations of cytolysin. Calcium failed to block both the binding and oligomer formation of cytolysins on the erythrocyte membrane. After pore formation, the continued presence of calcium is required for the prevention of hemolysis. There was hardly any inflow of calcium into the erythrocytes through pores as measured by 45Ca2+ uptake. The presence of calcium after the abolition of Ca2+ gradient by ionomycin cannot inhibit the hemolysis caused by cytolysin. These results suggest that calcium exerts its major inhibitory effect on V. vulnificus cytolysin-induced hemolysis as an osmotic protectant, and that cytolysin may become an useful tool for permeabilizing cells selectively for small ions such as potassium or sodium while preventing the Ca2+ flow.

Generation of strand breaks and formation of 8-hydroxy-2'-deoxyguanosine in DNA by a Thiol/Fe3+/O2-catalyzed oxidation system

Strand breaks are produced in pBluescript plasmid DNA by a metal-catalyzed oxidation system composed of Fe3+, O2, and a thiol as an electron donor. Formation of 8-hydroxy-2'-deoxyguanosine (8-OH-dG) in calf thymus DNA was also observed utilizing the same system. DNA damage was observed with the physiological thiols dihydrolipoic acid, glutathione, and cysteine as well as with the synthetic thiols dithiothreitol and 2-mercaptoethanol under a wide range of conditions. Both strand breaks and formation of 8-OH-dG in DNA were temperature dependent, occurring more rapidly at higher temperatures. Sodium azide and mannitol as well as a metal chelator, diethylenetriaminepentaactic acid, decreased strand breaks and 8-OH-dG formation in DNA. Superoxide dismutase did not block damage to DNA, whereas a thiol-dependent protector protein from Saccharomyces cerevisiae and catalase inhibited DNA damage in a concentration-dependent manner. The results of the present study indicate that H2O2 may be generated from a thiol/Fe3+/O2 system and that hydroxyl free radicals may be produced by metal-catalyzed Fenton reactions and may be the ultimate species mediating the DNA damage.

Impairement of endothelium-dependent relaxation in chronic two-kidney, one clip hypertensive rats

OBJECTIVES

Hypertension is commonly associated with an endothelial dysfunction that may contribute to the rise in blood pressure. Little information has been available so far on the role of endothelium-derived nitric oxide(EDNO) in renin-dependent, 2-kidney, 1 clip(2KIC) hypertension. The present study was aimed to determine a role for EDNO in the development and maintenance of 2KIC hypertension.

METHODS

The effects of blocking synthesis or supplementation with precursor of EDNO on the development of hypertension were determined in 2KIC rats. Vascular responses to acetylcholine, nitroprusside, atrial natriuretic peptide and nifedipine were examined in 7- and 12-week hypertensive 2KIC rats.

RESULTS

NG-nitro-L-arginine-methyl ester caused a sustained increase of blood pressure in normal rats, while it was only partially associated with a more pronounced increase of blood pressure in the developmental phase of hypertension in 2KIC rats. In 7-week and 12-week hypertensive rats, phenylephrine-induced contraction of the isolated thoracic aortic rings was more sensitive compared with control. Their acetylcholine-induced relaxation was attenuated while the responses to nitroprusside or atrial natriuretic peptide were unaltered. Although their blood pressure did not differ between 7-week and 12-week hypertensive groups, the attenuation in the acetylcholine-induced relaxation was more prominent in the latter with a longer duration of hypertension. Indomethacin did not affect the attenuated relaxation to acetylcholine. The relaxation response to nifedipine was more pronounced in 2KIC rats.

CONCLUSION

These results indicate that ENDO has little influence of the 2KIC hypertension, at least during its developmental phase, which is associated with an activated reninangiotensin system. The chronic stage of 2KIC hypertension, however, is associated with an endothelial dysfunction which may contribute to the enhanced vasoconstriction and sustained high blood pressure.

Inhibition of metal-catalyzed oxidation systems by a yeast protector protein in the presence of thioredoxin

A protector protein from Saccharomyces cerevisiae specifically prevents the inactivation of enzymes caused by a thiol/Fe3+/O2 metal-catalyzed oxidation system but not by an ascorbate/Fe3+/O2 system. Ascorbate/Fe3+/O2-mediated damage of enzymes could be prevented by the protector protein only in the presence of reduced thiol. We demonstrate that two proteins from yeast, thioredoxin plus another protein having properties similar to that expected to thioredoxin reductase, when presented with NADPH and the yeast protector protein prevented inactivation of E. coli glutamine synthetase by the ascorbate/Fe3+/O2 system. This system also removes hydrogen peroxide effectively. We also demonstrate evidence suggesting that the NADPH-dependent thioredoxin system reactivates protector protein by reversible disulfide-dithiols exchange.