Decreased redox state in red blood cells from patients with sarcoidosis

BACKGROUND AND AIM OF THE WORK

The glutathione system has a key role in the defence against oxidative stress. To function properly, this system needs NADPH to maintain glutathione (GSH) in its reduced form. We hypothesized that the clinical problems associated with sarcoidosis might be related to a decreased anti-oxidant defence and we therefore measured the activity of the NADPH-generating enzyme glucose-6-phosphate dehydrogenase (G6PD), the GSH-regenerating enzyme glutathione reductase (GR) and indirectly the level of NADPH in red blood cells from patients with sarcoidosis.

METHODS

In a population of sarcoidosis (n = 88) patients, G6PD, GR and GR activity after incubation with chromate (GR-Cr) were measured in erythrocytes. A decreased concentration of NADPH was revealed by an increased GR-Cr (> 0.6 IU/g Hb). To exclude a mutation in the G6PD gene, sequencing was performed in cases with an abnormal GR-Cr. Sarcoidosis pulmonary disease severity was evaluated by means of laboratory data, radiographic staging, HRCT scoring, pulmonary function and exercise capacity testing.

RESULTS

Fourteen (29.2%) females and one (2.5%) male demonstrated an increased GR-Cr test, indicative of a decreased NADPH level. Patients with an abnormal test result demonstrated also significantly increased ACE and GR values (p < 0.05). Only one female case (of 6 tested) appeared to have a mutation in the G6PD gene.

CONCLUSION

In a considerable percentage of female patients with sarcoidosis, a decreased level of NADPH in the erythrocytes was found.

Effects of fatty liver induced by niacin-free diet with orotic acid on the metabolism of tryptophan to niacin in rats

The effects of dietary orotic acid on the metabolism of tryptophan to niacin in weaning rats was investigated. The rats were fed with a niacin-free, 20% casein diet containing 0% (control diet) or 1% orotic acid diet (test diet) for 29 d. Retardation of growth, development of fatty liver, and enlargement of liver were observed in the test group in comparison with the control group. The concentrations of NAD and NADP in liver significantly decreased, while these in blood did not decrease compared to the control group. The formation of the upper metabolites of tryptophan to niacin such as anthranilic acid, kynurenic acid, and 3-hydroxyanthranilic acid were not affected, but the quinolinic acid and beyond, such as nicotinamide, N1-methylnicotinamide, N1-methyl-2-pyridone-5-carboxamide, and N1-methyl-4-pyridone-3-carboxamide, were significantly reduced by the administration of orotic acid. Therefore, the conversion ratio of tryptophan to niacin significantly decreased in the test group in comparison with the control group.

Efficacy of turmeric on blood sugar and polyol pathway in diabetic albino rats

In the traditional system of medicine, Ayurveda, several spices and herbs are thought to possess medicinal properties. Among the spices, turmeric rhizomes (Curcuma longa. Linn.) are used as flavoring and coloring agents in the Indian diet everyday. In this research, we studied the effect of turmeric and its active principle, curcumin, on diabetes mellitus in a rat model. Alloxan was used to induce diabetes. Administration of turmeric or curcumin to diabetic rats reduced the blood sugar, Hb and glycosylated hemoglobin levels significantly. Turmeric and curcumin supplementation also reduced the oxidative stress encountered by the diabetic rats. This was demonstrated by the lower levels of TBARS (thiobarbituric acid reactive substances), which may have been due to the decreased influx of glucose into the polyol pathway leading to an increased NADPH/NADP ratio and elevated activity of the potent antioxdiant enzyme GPx. Moreover, the activity of SDH (sorbitol dehydrogenase), which catalyzes the conversion of sorbitol to fructose, was lowered significantly on treatment with turmeric or curcumin. These results also appeared to reveal that curcumin was more effective in attenuating diabetes mellitus related changes than turmeric.

[A simple and reliable spectrophotometric method for quantification of pyridine nucleotides in serum]

Pyridine nucleotides plays an important role in the maintenance of cellular homeostasis and its disturbance also involves in many perturbance of metabolism, so a simple and reliable assay for determination of oxidized and reduced pyridine nucleotides in serum would be significantly necessary in understanding the redox status of body. A novel modified method, which is based on Nisselbam and making use of a cycling enzymatic reaction and spectrophotometric assay to measure the pyridine nucleotides in serum, showed good results. The standard curve has fine linear relationship; the recovery of added standard samples is almost perfect. Twenty-seven samples from 27 normal subjects were examined by the method. The results were: NADPH 8.385 +/- 1.516 nmol/ml, NADP+ 3.624 +/- 0.985 nmol/ml, and NADPH/NADP+ 2.3612 +/- 0.8057; no significant difference in the variables was found between the male and female. This is a sensitive, simple, reliable and easy-practicing method for oxidized and reduced pyridine nucleotides assay.

Effects of dietary pyrazinamide, an antituberculosis agent, on the metabolism of tryptophan to niacin and of tryptophan to serotonin in rats

The effects of pyrazinamide on the metabolism of tryptophan to niacin and of tryptophan to serotonin were investigated to elucidate the mechanism for pyrazinamide action against tuberculosis. Weanling rats were fed with a diet with or without 0.25% pyrazinamide for 61 days. Urine samples were periodically collected for measuring the tryptophan metabolites. The administration of pyrazinamide significantly increased the metabolites, 3-hydroxyanthranilic acid and beyond, especially quinolinic acid, nicotinamide, N'-methylnicotinamide, and N1-methyl-4-pyridone-3-carboxamide, and therefore significantly increased the conversion ratio of tryptophan to niacin and the blood NAD level . However, no difference in the upper metabolites of the tryptophan to niacin pathway such as anthranilic acid, kynurenic acid and xanthurenic acid was apparent between the two groups. No difference in the concentrations of trytptophan and serotonin in the blood were apparent either. It is suggested from these results that the action of pyrazinamide against tuberculosis is linked to the increase in turnover of NAD and to the increased content of NAD in the host cells.

Elevation of blood NAD level after moderate exercise in young women and mice

We previously reported that the blood NAD levels are decreased by severe exercise, and administration of nicotinamide, a precursor of NAD, improves the endurance capacity of mice. In the present study, we determined whether moderate exercise changes the blood NAD levels in humans and mice. College female students exercised moderately with bike-ergometers. The blood NAD levels elevated after moderate exercise. Mice were forced to swim in a running water pool for 5 min as a moderate exercise, 15 min as a strong exercise, and until exhaustion as a severe exercise (average swimming time was 28.7 min). A 5 min swim gave a result similar to that of moderate exercise by human subjects. However, the blood NAD levels decreased after all-out exercise. The changes in whole blood tryptophan (a precursor of pyridine nucleotides) levels were similar to that in NAD. The glucose levels in whole blood and the non-esterified fatty acid levels in serum decreased according to exercising time. These data are the first demonstration of moderate exercise raising the blood NAD levels in human and mice. Elevation of the blood NAD levels may reflect changes in niacin metabolism that occur in response to exercise.

Interferon-gamma and sinusoidal electric fields signal by modulating NAD(P)H oscillations in polarized neutrophils

Metabolic activity in eukaryotic cells is known to naturally oscillate. We have recently observed a 20-s period NAD(P)H oscillation in neutrophils and other polarized cells. Here we show that when polarized human neutrophils are exposed to interferon-gamma or to ultra-low-frequency electric fields with periods double that of the NAD(P)H oscillation, the amplitude of the NAD(P)H oscillations increases. Furthermore, increases in NAD(P)H amplitude, whether mediated by interferon-gamma or by an oscillating electric field, signals increased production of reactive oxygen metabolites. Hence, amplitude modulation of NAD(P)H oscillations suggests a novel signaling mechanism in polarized cells.

Reduction of hydroxamic acids to the corresponding amides catalyzed by rabbit blood

1. The hydroxamic acids N-hydroxyphenacetin and N-hydroxy-2-acetylaminofluorene were reduced to the corresponding amides, phenacetin and 2-acetylaminofluorene respectively by rabbit blood supplemented with both NAD(P)H and FAD. These reducing activities were found in erythrocytes but not in plasma, and were sensitive to inhibition by carbon monoxide and oxygen. When blood or erythrocytes were boiled, these activities were not abolished. 2. Haemoproteins such as haemoglobin and catalase exhibited the reductase activity in the presence of both NAD(P)H and FAD under anaerobic conditions. The activity was not abolished when the haemoproteins were boiled. 3. Haematin showed a significant reducing activity in the presence of these cofactors. The activity of haematin was also observed with the photochemically reduced form of FAD. 4. The reduction system in blood was composed of NAD(P)H, FAD and haemoglobin. Reduction appears to proceed in two steps, i.e. the reduction of FAD by NADH or NADPH, followed by the non-enzymatic reduction of the hydroxamic acids to the amides by reduced FAD, catalyzed by the haem group of haemoglobin in rabbit erythrocytes.

Crystallization and preliminary structural results of catalase from human erythrocytes

Catalase (hydrogen peroxide:hydrogen peroxide oxidoreductase, E.C. 1. 11.1.6) is present in most aerobic prokaryotic and eukaryotic cells. Despite a large number of studies on catalases, the only mammalian catalase structure available is that from beef liver, in which about 50% of the haem groups are degraded to bile pigments. Three different crystal forms of human erythrocyte catalase were obtained by the hanging-drop vapour-diffusion technique using PEG as precipitant. Monoclinic crystals, with space group P21 and unit-cell parameters a = 102.9, b = 140.0, c = 173.6 A and beta = 103.2 degrees, require NADP(H) in the crystallization solution. Two types of hexagonal packing, with unit-cell parameters of either a = b = 86. 9, c = 255.5 A or a = b = 90.0, c = 521.2 A, were obtained under identical crystallization conditions in the absence of NADP(H). Only one diffraction data set could be collected: this was obtained from the hexagonal crystals with the smaller c axis using synchrotron radiation, with resolution to 2.65 A. A molecular-replacement solution, determined using a modified beef-liver catalase model as a search structure, corresponds to space group P6422 and contains a single subunit in the asymmetric unit, with an estimated solvent volume of about 50%. The packing determined suggests how minor rearrangements might allow the transition between both hexagonal crystal forms and provides an explanation for the anisotropic character of the corresponding diffractions.

Polyol pathway activation and glutathione redox status in non-insulin-dependent diabetic patients

The current study aimed to evaluate whether nicotinamide adenine dinucleotide phosphate (NADPH) alteration in erythrocytes from patients with non-insulin-dependent diabetes mellitus (NIDDM) is responsible for the impaired glutathione (GSH) redox status, and to assess if short-term inhibition of the polyol pathway normalizes NADPH levels and GSH redox status via an amelioration of the NADPH/total NADP (tNADP) ratio. For this purpose, erythrocyte NADPH and GSH levels were measured in 18 NIDDM patients at baseline and then after 1 week of random double-blind assignment to treatment with either tolrestat (an aldose reductase inhibitor, 200 mg daily) (n = 12) or placebo (n = 6). A group of 16 healthy volunteers served as the control. In the basal condition, mean GSH (P < .0001) and NADPH (P < .0001) levels and NADPH/tNADP (P < .0001) and GSH/ glutathione disulfide (GSSG) (P < .005) ratios were lower in NIDDM patients than in control subjects. Tolrestat treatment increased GSH levels (P < .05 v placebo and baseline) and the NADPH/tNADP ratio (P < .05 v placebo and baseline). Interestingly, tolrestat-induced changes in GSH and NADPH levels and in GSH/GSSG and NADPH/tNADP ratios were significant only in patients who showed a decreased NADPH/tNADP ratio at baseline (n = 8). In these latter patients, we also found a direct correlation between percentage increments in GSH levels and NADPH/tNADP ratios after tolrestat treatment (r = .71, P < .05). In conclusion, our findings support the hypothesis that polyol pathway activation decreases NADPH and GSH levels. Accordingly, short-term inhibition of this enzymatic route increased both the GSH level and the NADPH/tNADP ratio. These changes were observable only in the subgroup of patients with an abnormal NADPH/tNADP ratio at baseline. Polyol pathway inhibition could be useful for decreasing oxidative stress in NIDDM.

Elevated expression of p47phox and p67phox proteins in neutrophils from burned rats

The molecular control of neutrophil respiratory burst in burn injury was investigated through quantitation of protein factors, p47phox and p67phox, which are required for the activation of the phagocyte plasma membrane NADPH-oxidase. Circulating neutrophils were isolated from rats with 30% body surface area covered with full thickness burns. Neutrophil O2- generation, and p47phox and p67phox expressions, respectively, were determined using spectrophotometric and immunoblot techniques. Formylmethionyl-leucyl-phenylalanine stimulated superoxide anion generation was approximately 50% higher in neutrophils from rats 24 and 72 h after burns compared with that in sham control rats. The level of superoxide production was .47 +/- .05 nanomoles per minute per 10(6) cells (mean +/- SE, n = 6) at 24 h and .45 +/- .05 (n = 6) at 72 h postburn, whereas in sham control animals it was .32 +/- .02 (n = 8). Compared with the sham group p47phox levels, p47phox expression was 5.7-fold, 4.4-fold, and 4.5-fold higher, respectively, at 24, 36 and 72 h postburn. The levels of p67phox in burned animals were 2-fold higher than in the sham group, (p < .05) at 24 h postburn, and approximately 50% higher than sham at 36 h after the burn. The p67phox levels in rats 72 h after the burn were not significantly different from the sham values. These data support the occurrence of an up-regulation of p47phox and p67phox expressions accompanying the enhanced neutrophil respiratory burst activity during the early stages of burn injury. The up-regulation of p47phox and p67phox could be responsible for the priming of neutrophil O2- production leading to host tissue injury.

[The role of NADPH in the development of neonatal jaundice with G6PD deficiency]

OBJECTIVE

To investigate the role of NADPH in the development of neonatal jaundice with G6PD deficiency.

METHODS

The enzyme activities of G6PD, catalse (Cat) and glutathione peroxidase (GSH-px) were measured by quantitative determination of enzyme activity. The level of MDA was analyzed with alpha-thiobarbituric acid and the level of NADPH was determined with modified Nisselbaum JS's. Comparisons of these markers between G6PD normal and deficient erythrocytes were made before and during the incubation of the erythrocytes with H2O2.

RESULTS

The level of MDA, which was 36 +/- 8n-mol.L-1.gHb-1, was increased and that of NADPH, which was 1792 +/- 106mumol.L-1.gHb-1, was decreased in jaundiced neonates with G6PD deficiency compared with those with normal G6PD activity. When the cells were incubated with H2O2, the level of NADPH and the activities of Cat and GSHpx in erythrocytes with normal G6PD activity increased at first, and then turned to decrease as the incubation lasted longer than 30 minutes. But in G6PD-deficient erythrocytes all these markers decreased continuously as the cells were incubated with H2O2.

CONCLUSIONS

The diminished capability of generation of NADPH in G6PD-deficient erythrocytes may contribute directly to the more extensive peroxidation of the cells. The defect capacity of generation of NADPH, which resulted in the weakened capability of antiperoxidation and finally the lysis of erythrocytes, was one of the important mechanisms in the development of jaundice in G6PD-deficient neonates.

Active involvement of catalase during hemolytic crises of favism

The endemic occurrence of favism in certain Mediterranean regions provided an investigative opportunity for testing in vivo the validity of claims as to the role of catalase in protecting human erythrocytes against peroxidative injury. Reduced activity of catalase was found in the erythrocytes of six boys who were deficient in erythrocytic glucose-6-phosphate dehydrogenase (G6PD) and who were studied while suffering hemolysis after ingesting fava beans. Activity of catalase was further reduced when their red blood cells were incubated with aminotriazole. In contrast, minimal reduction of catalase activity was found, both with and without incubation with aminotriazole, in erythrocytes of a G6PD-deficient boy who had ingested fava beans 7 days earlier and in erythrocytes of seven G6PD-deficient men with a past history of favism. These results confirmed earlier studies in vitro indicating that catalase is a major disposer of hydrogen peroxide in human erythrocytes and, like the glutathione peroxidase/reductase pathway, is dependent on the availability of reduced nicotinamide adenine dinucleotide phosphate (NADPH). The effect of divicine on purified catalase and on the catalase of intact G6PD-deficient erythrocytes was similar to the previously demonstrated effect on catalase of a known system for generating hydrogen peroxide. This effect of divicine strengthens earlier arguments that divicine is the toxic peroxidative component of fava beans.

Redox state, antioxidative activity and lipid peroxidation in erythrocytes and plasma of chronic ambulatory peritoneal dialysis patients

Red blood cells and plasma reduced and oxidized glutathione levels, glutathione peroxidase (GSH-Px) activity, thiobarbituric acid reactants (TBAR) of both chronic ambulatory peritoneal dialysis (CAPD) patients and a matched control group were investigated in this study. Oxidized and reduced pyridinic nucleotides in red blood cells (RBC), in which NADPH is a direct expression of hexose monophosphate shunt function, were also studied. The results obtained indicate that RBC and plasma are exposed to oxidative stress in CAPD. This condition is characterized by a decreased GSH/GSSG ratio, particularly evident in RBC as a consequence of the GSSG accumulation. Lipid peroxidation is increased, as indicated by raised TBAR levels, and reduced pyridinic nucleotides are decreased. Increased GSH-Px levels and unmodified or slightly increased GSH content were observed in the RBC but not in plasma, which showed decreased GSH and unmodified peroxidase activity. Peroxidase correlated positively with TBAR levels in the RBC lysates. In a subgroup of patients treated with erythropoietin (vs. untreated patients and controls) no differences were observed in the glutathione-related parameters studied. These data suggest that a mechanism for adaptation to oxidative conditions may be present in CAPD and its effects on RBC integrity are discussed in comparison with the hemodialysis conditions previously studied.

Single extraction method for the spectrophotometric quantification of oxidized and reduced pyridine nucleotides in erythrocytes

A simplified and reliable assay for the determination of erythrocyte pyridine nucleotide (NAD and NADP) concentrations, as well as the ratio of the reduced [NADH/NADPH] to oxidized [NAD+/NADP+] nucleotide, is important in understanding both normal and abnormal red blood cells (RBC). However, previously published methods for quantitating pyridine nucleotides are inappropriate for RBC, difficult to use, or inaccurate. The method described within this paper provides for both improved reliability and ease of use. In addition, we have documented that significant pools of NADPH and NADH are tightly bound to proteins (e.g., catalase) and not detectable by many of the assay systems previously used. This results in a significant change in not only total RBC pyridine nucleotide content but also in the ratio of reduced to nonreduced nucleotide.

Carbonyl reductase activity for acetohexamide in human erythrocytes

Acetohexamide is an oral antidiabetic agent and is metabolized by the reductive conversion of the acetoxy group to a secondary alcohol metabolite. In vivo, many drugs are metabolized by reductase enzymes; however, the characteristics of the enzymes that reduce carbonyl compounds need to be clarified. We tested whether reductase activity for acetohexamide can be found in human erythrocytes. Enzyme activity was monitored by formation of hydroxyhexamide using HPLC methods. In human erythrocytes, reductase activity (6.10 +/- 1.20 nmol/min/g hemoglobin) (mean +/- SD) was indeed observed, when 0.5 mM acetohexamide was used as a substrate. KM values and Vmax at the physiologically important pH 7.4 were 0.70 +/- 0.13 mM and 9.19 +/- 0.88 nmol/min/g hemoglobin, respectively. Separation of protein by gel filtration gave one major peak fraction with reductase activity whose molecular weight was estimated to be 31,000. Known substrates of carbonyl reductase such as menadione, daunorubicin, and ethacrynic acid inhibited the acetohexamide reduction. The acetohexamide reductase in erythrocyte showed characteristics of carbonyl reductase. Furthermore, acetohexamide reductase activity in erythrocyte was approximately 30% activity of that of human liver (0.17 +/- 0.05 nmol/min/mg cytosolic protein). The pattern of inhibitors in human liver was essentially the same as that in erythrocytes. It is plausible that the activity in erythrocytes may predict the activity in the liver. It was concluded that carbonyl reductase in human erythrocyte plays an important role in acetohexamide metabolism.

Activation of respiratory burst oxidase is accompanied by desensitization of p47phox in nucleoside-triphosphate binding along with its translocation to cell membrane

A cytosolic component of human neutrophils, p47phox, potentiates respiratory burst oxidase translocating from cytosol to membrane upon cell stimulation. In this study, the nucleotide-binding ability of p47phox was examined using [32P]GTP dialdehyde (oGTP), [32P]oATP, and [32P]oNADPH. p47phox showed affinities for both oGTP and oATP that were 14 times higher than that for oNADPH, suggesting that it is a nucleoside triphosphate (NTP)-binding protein rather than an NADPH-binding protein. Binding analysis of p47phox using either [32P]oGTP or [32P]oATP revealed an apparent binding constant for each individual NTP analogue and the same maximum binding value, which suggests that both NTPs share a common specific binding site. Stimulation of neutrophils with phorbol myristate acetate (PMA) resulted in enhancement of the oxidase activity to generate O2- anion and was accompanied by substantial translocation of p47phox to membrane. However, p47phox derived from the stimulated cell membrane had lost its NTP-binding ability, unlike that from the resting cytosol. These results suggest that the binding of NTP to p47phox may be involved in the process that activates the oxidase and is desensitized in translocated p47phox.

Erythrocyte redox state in uremic anemia: effects of hemodialysis and relevance of glutathione metabolism

Reduced and oxidized glutathione and pyridine coenzymes, glutathione-related enzymes and Cu,Zn-superoxide dismutase (Cu,Zn-SOD) were investigated in the RBC of patients with chronic renal failure (CRF) and in age- and sex-matched controls. The effects of hemodialysis (HD) were also studied. A defective RBC redox state was shown in the CRF group based on a decreased GSH/GSSG ratio and NADPH levels. Increased activities of glutathione transferase (GSH-S-T) and Cu,Zn-SOD were observed before HD. Dialysis apparently restores the levels of antioxidant enzymes and at the same time strongly affects the redox state. Thus we can speculate that HD can generate severe redox impairment inducing damage in RBC and plasma antioxidant enzymes. Increased erythrocyte GSSG and GSM-S-T levels coupled with a reduced hexose monophosphate shunt (HMPS) function may be useful indexes of oxidative stress in uremic anemia.

Variations of adenine nucleotide levels in normal and pathologic human erythrocytes exposed to oxidative stress

Normal human erythrocytes suspended in isotonic saline at 0.5 haematocrit displayed, after 30 min exposure to 1 mM tert-butylhydroperoxide at 37 degrees C, a marked increase of NADPH, while the concentration of the other adenine nucleotides was almost unchanged. Hereditary Spherocytosis and glucose-6-phosphate dehydrogenase-deficient red blood cells exhibited, under basal conditions, higher levels of most of the nucleotides assayed and significant amounts of hypoxanthine. Treatment with tert-butylhydroperoxide caused, in glucose-6-phosphate dehydrogenase-deficient erythrocytes, a pronounced decrease of ADP and of AMP levels, a substantial invariance of other adenine nucleotides and a considerable raise of hypoxanthine. On the contrary, Hereditary Spherocytosis erythrocytes exhibited, after oxidative stress, increased levels of ADP and of AMP, a slight decrease of ATP and an accumulation of hypoxanthine similar to that found in enzyme-deficient red cells. In both the pathologic erythrocytes the addition of phosphate during the oxidative treatment resulted in a lower formation of hypoxanthine, while the presence of 10 mM glucose, fully prevented its appearance.

HPLC determination of oxidized and reduced pyridine coenzymes in human erythrocytes

The nucleotide concentrations in acid and alkaline erythrocyte extracts have been measured by RP-HPLC in healthy controls and in patients bearing different inherited disorders, with altered erythrocyte NAD(P) levels. The objective was the simultaneous determination of the nucleotide profile and of the oxidative state of pyridine coenzymes by the most suitable extraction method. Both alkaline and acid extractions were necessary to obtain the complete pattern, due to defective recovery of the oxidized or reduced coenzymes, respectively, during the extraction procedures. Purine nucleotide quantification seemed to be reliable by all methods. High NADP+ levels were confirmed in two glucose-6-phosphate dehydrogenase deficient patients, coupled with raised NAD levels, lowered NADPH/NADP+ ratio and increased NADH/NAD+ ratio. Higher NAD+ and normal or lower NADH/NAD+ ratios were found in two hypoxanthine-phosphoribosyltransferase deficient patients, while a patient with superactive phosphoribosylpyrophosphate synthetase showed a decreased NADH level in addition to the low NAD+ level previously found.

Niacin deficiency and cancer in women

A new interest in the relationship between niacin and cancer has evolved from the discovery that the principal form of this vitamin, NAD, is consumed as a substrate in ADP-ribose transfer reactions. Poly(ADP-ribose) polymerase, an enzyme activated by DNA strand breaks, is the ADP-ribosyltransferase of greatest interest with regard to effects on the niacin status of cells since its Km for NAD is high, and its activity can deplete NAD. Studies of the consequences of DNA damage in cultured mouse and human cells as a function of niacin status have supported the hypothesis that niacin may be a protective factor that limits carcinogenic events. To test this hypothesis in humans, we used a biochemical method based on the observation that as niacin nutriture decreases, NAD readily declines and NADP remains relatively constant. This has been demonstrated in both fibroblasts and in whole blood from humans. Thus, we use "niacin number," (NAD/NAD+NADP) x 100% from whole blood, as a measure of niacin status. Healthy control subjects showed a mean niacin number of 62.8 +/- 3.0 compared to 64.0 for individuals on a niacin-controlled diet. Analyses of women in the Malmö Diet and Cancer Study showed a mean niacin number of 60.4 with a range of 44 to 75. The distribution of niacin status in this population was nongaussian, with an unpredictably large number of individuals having low values.

[Respiratory reactivity and parameters of nonspecific immunity in workers of the Chernobyl nuclear power plant during adaptation to mountain climate]

The quantitative composition of the peripheral blood, enzymatic activity of neutrophils and hypoxic ventilatory drive were determined in people working at the Chernobyl NPP during sojourn for 28 days in the Caucasus mountains at 220 m altitude with a periodical climbing up to 4200 m. At the initial state we found neutropenia, lymphocytosis, an increase in the number of prolymphocytes and big hairy lymphocytes, a decrease in the number of small lymphocytes, fall in activity of enzymes responsible for oxygen-dependent and oxygen-independent mechanisms of bactericidity. The indices of sensitivity to the hypoxic respiration stimulus did not essentially differ from the norm. Staying at altitude promoted normalization of the number of segmento-nuclear neutrophils, lymphocytes (their small population, in particular), an increase in the number of eosinophiles of the peripheral blood. Changes in the activity of myeloperoxidase, NADP-oxidase and cationic proteins in the neutrophils were observed. A considerable increase of the ventilatory drive to the hypoxic respiration stimulus was determined. Accentuation of fermentative transformations proved to be closely related to the ventilatory response to hypoxia: weak activation of NADP-oxidase and a decrease of myeloperoxidase activity were observed in people with initially low respiration reactivity, while a considerable increase in activity of these enzymes and in content of cationic proteins was observed in people with high respiration reactivity. Individual peculiarities of the reaction to staying at altitude should be taken into account when developing particular methods of immune correction.