The effect of zinc deficiency on alkaline phosphatase (EC 3.1.3.1) and its isoenzymes

Evaluation of treatment with zinc acetate hydrate in patients with liver cirrhosis complicated by zinc deficiency

AIM

In Japan, no zinc preparation had been approved for therapeutic purposes before March 2017. Zinc acetate hydrate was recently approved for the treatment of hypozincemia. We evaluated the efficacy and safety of treatment with zinc acetate hydrate.

METHODS

A total of 97 patients with cirrhosis complicated by hypozincemia were treated with zinc acetate hydrate, and their serum zinc normalization rates; factors contributing to normalization; changes in blood ammonia levels; branched-chain amino acids-to-tyrosine ratios; levels of albumin, hemoglobin, alkaline phosphatase, serum copper, and iron; incidence of adverse events; improvement in subjective symptoms; and serum zinc levels taken at 3 months post-treatment were determined.

RESULTS

The cumulative serum zinc normalization rates, when normalization was defined as achievement of a serum zinc level ≥80 μg/dL, after 2, 4, and 6 months of treatment were 64.9%, 80.3%, and 82.5%, respectively. Multivariate analysis identified an albumin level of ≥3.3 g/dL and branched-chain amino acids to tyrosine ratio of ≥3.46 as factors contributing to zinc normalization within 3 months of treatment. Treatment resulted in a significant decrease in blood ammonia and serum copper levels, and significant increases in branched-chain amino acids-to-tyrosine ratios and alkaline phosphatase levels. Seven (7.2%) patients prematurely discontinued treatment due to hypocupremia. By the end of treatment, subjective symptoms had resolved in 46.2% of patients. By 3 months post-treatment, serum zinc levels had reverted to levels close to those at baseline.

CONCLUSIONS

Treatment with zinc acetate hydrate resulted in normalization of serum zinc levels at a high rate. The main reasons for discontinuation of treatment included hypocupremia.

Zinc deficiency in patients with chronic liver disease in Japan

AIM

This study aimed to determine the distributions of serum zinc levels and the prevalence of zinc deficiency in patients with chronic liver disease (CLD) in actual clinical practice, and to analyze the association between serum zinc levels and clinical characteristics.

METHODS

This study analyzed 1973 patients with CLD, including 749 with liver cirrhosis, who were admitted to Sapporo Kosei General Hospital in 2017.

RESULTS

Zinc deficiency, defined as a serum zinc level of <60 μg/dL, was observed in 555 patients overall (28.1%), including 182 (14.9%) patients without liver cirrhosis and 373 (49.8%) with liver cirrhosis. When marginal zinc deficiency was included, zinc deficiency (serum zinc level <80 μg/dL) was observed in 1594 (80.8%) patients overall, including 924 (75.5%) patients without liver cirrhosis and 670 (89.5%) with liver cirrhosis. Serum zinc levels were most strongly correlated with serum albumin levels. Of the 257 CLD patients with an albumin level of <3.5 g/dL, 234 (91.1%) had a serum zinc level of <60 μg/dL.

CONCLUSIONS

Zinc deficiency is common in patients with CLD. Serum zinc levels should be regularly measured, particularly in patients with liver cirrhosis.

Interaction between zinc, cadmium, and lead in scalp hair samples of Pakistani and Irish smokers rheumatoid arthritis subjects in relation to controls

The incidence of rheumatoid arthritis (RA) has been associated with cigarette smoking. The aim of our study was to assess the trace essential and toxic metals, cadmium (Cd), lead (Pb), and zinc (Zn), in scalp hair samples of 32 Irish and 46 Pakistani smokers and non-smokers RA male patients with age range 42-56 years. For comparison purpose, the scalp hair samples of 27 Irish and 55 Pakistani non-RA male subjects of the same age group were collected. The concentrations of trace and toxic elements were measured by inductive coupled plasma atomic emission spectrophotometer and atomic absorption spectrophotometer prior to microwave-assisted acid digestion. The validity and accuracy of the methodology was checked using certified reference materials and using conventional wet acid digestion method on the same certified reference materials (CRMs). The recovery of all studied elements was found to be in the range of 97.5-99.7% of certified reference values of CRMs. The results of this study showed that the mean values of Cd and Pb were significantly higher in scalp hair samples of both smoker and non-smoker RA patients than in referents (P < 0.001), whereas the concentration of Zn was lower in the scalp hair samples of smokers and non-smokers rheumatoid arthritis patients. The deficiency of Zn and the high exposure of Cd and Pb as a result of cigarette smoking may be synergistic risk factors associated with rheumatoid arthritis.

Studies on the interaction of poly(N-vinylpyrrolidone) with no-carrier-added 61Cu, 62Zn, 66Ga, 69Ge and 71As using tracer packet technique

Interactions of no-carrier-added radionuclides 61Cu, 62Zn, 66Ga, 69Ge and 71As with poly(N-vinylpyrrolidone) (PVP) were studied in multi-elemental environment by dialysis with the help of tracer packet technique. It has been observed that in acidic pH gallium has a high tendency for formation of Ga-PVP complex while the same is true for Cu and Zn in neutral and basic pH. Germanium is always inert towards the interaction with PVP at all pH values. No interaction of arsenic was observed in acidic and neutral pH; while in basic pH the tendency to form As-PVP complex is considerably higher. The result can be considered as a model of in-vivo interaction of PVP-Ga/Cu/Zn/As complexation.

Characterization of structural and catalytic differences in rat intestinal alkaline phosphatase isozymes

To understand the differences between the rat intestinal alkaline phosphatase isozymes rIAP-I and rIAP-II, we constructed structural models based on the previously determined crystal structure for human placental alkaline phosphatase (hPLAP). Our models of rIAP-I and rIAP-II displayed a typical alpha/beta topology, but the crown domain of rIAP-I contained an additional beta-sheet, while the embracing arm region of rIAP-II lacked the alpha-helix, when each model was compared to hPLAP. The representations of surface potential in the rIAPs were predominantly positive at the base of the active site. The coordinated metal at the active site was predicted to be a zinc triad in rIAP-I, whereas the typical combination of two zinc atoms and one magnesium atom was proposed for rIAP-II. Using metal-depleted extracts from rat duodenum or jejunum and hPLAP, we performed enzyme assays under restricted metal conditions. With the duodenal and jejunal extract, but not with hPLAP, enzyme activity was restored by the addition of zinc, whereas in nonchelated extracts, the addition of zinc inhibited duodenal IAP and hPLAP, but not jejunal IAP. Western blotting revealed that nearly all of the rIAP in the jejunum extracts was rIAP-I, whereas in duodenum the percentage of rIAP-I (55%) correlated with the degree of AP activation (60% relative to that seen with jejunal extracts). These data are consistent with the presence of a triad of zinc atoms at the active site of rIAP-I, but not rIAP-II or hPLAP. Although no differences in amino acid alignment in the vicinity of metal-binding site 3 were predicted between the rIAPs and hPLAP, the His153 residue of both rIAPs was closer to the metal position than that in hPLAP. Between the rIAPs, a difference was observed at amino acid position 317 that is indirectly related to the coordination of the metal at metal-binding site 3 and water molecules. These findings suggest that the side-chain position of His153, and the alignment of Q317, might be the major determinants for activation of the zinc triad in rIAP-I.

Serum alkaline phosphatase activity during zinc deficiency and long-term inflammatory stress

A decrease in serum zinc can be caused by a real zinc deficiency but can also be caused by an apparent zinc deficiency, e.g. in inflammatory stress. The aim of this study was to evaluate the diagnostic power of serum alkaline phosphatase (AP) activity in the discrimination between pathophysiologic states of "real" and "apparent" zinc deficiency. A decrease in serum zinc was induced in growing and adult rats, by providing a diet low in zinc and by causing inflammatory stress. AP activity was determined using reagents low or enriched in zinc. Serum AP was decreased in zinc-deficient adult rats (P < 0.01). In zinc-deficient growing rats AP activity was not different from normal rats but AP activity decreased rapidly. In the same growing rats a significant difference was found in AP activities determined using buffers low and enriched in zinc (P < 0.001) between both groups of rats. After inducing inflammatory stress a decrease in AP activity (P < 0.01) and serum zinc (P < 0.001) was seen during the first few days. After the initial phase of inflammation AP activity normalized, serum zinc showed a rise which after correction for the decrease in serum albumin reached the level of the control rats. A difference in AP activity in buffers low and enriched in zinc was observed only during the first few days after induction of inflammatory stress (P < 0.001). Probably the method of measurement of the difference in enzyme activity, using buffers low and enriched in zinc, can be used as an indication for zinc deficiency in situations with changing AP enzyme concentrations. AP activity is decreased during the initial phase of inflammatory stress due to a decrease in serum zinc.

Lipid deposition in intestine as a possible cause of malabsorption of nutrients in zinc-deficient common carp (Cyprinus carpio)

An experiment was performed to examine the interaction between Zn deficiency and lipid intake in carp. The carp were given a high-lipid diet that was either Zn-deficient (ZD) or Zn-supplemented (ZS), or were pair-fed (PF) the ZS diet to the intake of the ZD group. After 8 weeks the carp were killed and measurements were made of intestinal glucose uptake, levels of DNA, RNA and triacylglycerol, and alkaline phosphatase (EC 3.1.3.1) activity in liver and intestine samples. A further group of similar carp were given the same diets but at week 8 were transferred to low-lipid diets, with the exception of half the ZD group. After a further 8 weeks of treatment, carps were killed for biochemical studies. Intestinal [14C]glucose uptake, levels of DNA, RNA and alkaline phosphatase activity in intestine and liver were significantly (P < 0.05) lower in the high-lipid ZD group than in the high-lipid ZS and PF diet groups. The triacylglycerol concentration in the intestine was higher in the high-lipid ZD group than in the other two groups. When the carp were given the corresponding low-lipid diets, the variables measured in intestine and liver of the ZD group were close to those of the other groups. The results of this study demonstrate that lipid, when present in excess in the diet, accumulates in the intestine under Zn-deficient conditions and may reduce the absorption of glucose in carp. The reduced RNA and DNA levels and alkaline phosphatase activity in liver and intestine of ZD fish compared with those of ZS fish given high-lipid diets is proposed to be due to the malabsorption of nutrients linked with lipid deposition in the intestine, rather than their dependence on the level of Zn in the diet.

Changes in the fetal tibial growth plate secondary to maternal zinc deficiency in the rat: a histological and histochemical study

Zinc deficiency (ZD) is teratogenic in rats, and fetal skeletal defects are prominent. To elucidate further the effects of maternal ZD in the fetal skeleton, we performed a morphological and histochemical study of tibial growth plate (GP) in ZD rat fetuses. The histochemical study included the identification of calcium, of hydrolytic enzymes associated with the process of calcification, and of oxidative enzymes related to energy production and to the synthesis of proteoglycans. Pregnant Sprague-Dawley rats were fed (1) a control diet (76.4 micrograms Zn/g diet) ad libitum (group C), (2) a zinc-deficient diet (0 micrograms/g) ad libitum (group ZD), or (3) the control diet pair-fed to the ZD rats (group PF). On day 21 of gestation, laparotomies were performed, the fetuses were removed, and fetal tibiae obtained. Specimens were stained with hematoxylin-eosin (H&E) and Masson Trichrome and were processed for identification of alkaline phosphatase, adenosine triphosphatase, succinic dehydrogenase, NADH dehydrogenase, and calcium. The morphologic patterns found in ZD fetal tibiae indicated defects in various cell types implicated in bone metabolism. Staining for hydrolytic enzymes revealed alterations in the size and distribution of matrix vesicles and a weaker staining for ATPase in ZD fetuses. Staining for oxidative enzymes was overall more intense in ZD fetal tibiae. ZD fetuses also presented irregular and defective calcification. These findings indicate that severe maternal ZD in the rat results in structural and functional alterations in the GP of fetal bone, leading to a defective endochondral ossification.

Lasting effects of early chronic caffeine feeding on rats' behavior and brain in later life

Pregnant dams were fed a 20% protein diet with caffeine (2 mg/100 g b.wt.), starting on day 9 of gestation. At birth, each dam with 8 assigned pups was fed this diet until weaning, day 22. On day 22, female rats were caged and fed this diet until day 93. Starting on day 93, the caffeine-supplemented diet was replaced with a caffeine-free, 20% protein diet until day 388. Starting on day 31, each animal was placed in a photoactivity cage, and locomotive activity was measured until day 375. On day 388, the animals were killed, and their brains were removed and divided into 7 regions. The weight, DNA, protein and zinc contents, and alkaline phosphatase activity of each region were determined. Locomotive activity of the caffeine-fed group was higher than in the noncaffeine control group. Accumulative activity scores showed 3 subgroups (high, medium, and low) in both groups at day 93. The medium activity subgroup in the caffeine group was greater than the controls from day 72 to day 93. These differences reappeared 5 weeks after cessation of caffeine supplementation and continued until day 375. The differences in activity were minimum in the high and low subgroups. Chronic caffeine intake in early life permanently affected the medium activity subgroup. Furthermore, various regions of the brain were biochemically altered in spite of the feeding of a noncaffeine diet for almost 300 days after caffeine.

Esophageal cancer and microelements

Epidemiological studies have identified dietary zinc deficiency, methylbenzylnitrosamine, and ethanol as factors strongly associated with an increased incidence of esophageal carcinoma in man. In addition, these studies have identified other trace elements which may also affect the incidence of esophageal carcinoma. Animal models have confirmed that dietary zinc deficiency increases the incidence of methylbenzylnitrosamine-induced esophageal carcinoma and that dietary zinc deficiency also increases the incidence of other dialkylnitrosamine-induced carcinomas. The dialkylnitrosamine carcinogens are activated by NADPH-dependent cytochrome P-450 enzymes in their target tissues. The activated methylbenzylnitrosamine methylates DNA, forming O6-methylguanine adducts. These O6-methylguanine adducts can lead to point mutations in DNA, and such mutations are known to be responsible for the induction of certain carcinogen-induced tumors. We have demonstrated that dietary zinc deficiency increased the cytochrome P-450-dependent microsomal metabolism of methylbenzylnitrosamine and dimethylnitrosamine, two members of this class of dialkylnitrosamine carcinogens, while the addition of zinc in vitro noncompetitively inhibits the microsomal metabolism of these carcinogens. We have also demonstrated that dietary zinc deficiency is associated with an increased formation of O6-methylguanine in the esophageal DNA of zinc-deficient animals treated with methylbenzylnitrosamine. This increased formation of the mutagenic DNA adduct O6-methylguanine may explain the increased incidence of dialkylnitrosamine-induced carcinomas observed with dietary zinc deficiency. Other trace elements, including molybdenum, selenium, and magnesium, may also alter the incidence of esophageal carcinoma, but studies of these elements are not as conclusive as the epidemiological and experimental studies linking dietary zinc deficiency with an increased incidence of human esophageal carcinoma.

Teratogenicity of zinc deficiency in the rat: study of the fetal skeleton

Zinc deficiency (ZD) is teratogenic in rats, and fetal skeletal defects are prominent. This study identifies fetal skeletal malformations that affect calcified and non-calcified bone tissue as a result of gestational zinc deficiency in rats, and it assesses the effect of maternal ZD in fetal bone calcification. Pregnant Sprague-Dawley rats (180-250 g) were fed 1) a control diet (76.4 micrograms Zn/g diet) ad libitum (group C), 2) a zinc-deficient diet (0 microgram/g) ad libitum (group ZD), or 3) the control diet pair-fed to the ZD rats (group PF). On day 21 of gestation, laparotomies were performed. Fetuses were weighed, examined for external malformations, and stained in toto with a double-staining technique for the study of skeletal malformations. Maternal and fetal tissues were used for Zn, Mg, Ca, and P determinations. Gross external malformations were present in 97% of the ZD fetuses. No external malformations were found in fetuses from groups C and PF. Ninety-one percent of cleared ZD fetuses had multiple skeletal malformations, whereas only 3% of the fetuses of group PF had skeletal defects; no skeletal malformations were found in fetuses from group C. Some of the skeletal malformations described in the ZD fetuses, mainly affecting non-calcified bone, were not mentioned in previous reports, thus stressing the importance of using double-staining techniques. Examination of stained fetuses and counting of ossification centers revealed important calcification defects in ZD fetuses. These effects were confirmed by lower Ca and P concentrations in fetal bone with alteration of the Ca:P ratio.

Effects of different levels of caffeine supplemented to the maternal diet on the brains of newborn rats and their dams

At birth, dams with 8 randomly assigned pups were divided into three groups. Dams of group 1 were fed a control diet. Dams of groups 2 and 3 were fed the control diet supplemented with caffeine (1 mg and 2 mg/100 g body weight, respectively). Pups were killed at day 15 and their brains removed. After weighing, brains were analyzed for DNA, protein, cholesterol, zinc and alkaline phosphatase activity. Brain and plasma caffeine levels were also determined on groups 2 and 3. The dams were milked to measure caffeine levels. The brains from the dams were analyzed for the same parameters as the pups. Caffeine levels in group 3 were consistently higher than in group 2. In the pups, body and brain weights were heavier in group 3 than in the controls. Protein and cholesterol concentrations in group 2 were less than either controls or group 3. Alkaline phosphatase activity in group 2 was higher than either controls or group 3. In the dams, DNA concentration in groups 2 and 3 was less than the controls. Protein and cholesterol concentration in group 2 was less than group 3. It was concluded that low levels of caffeine in the maternal diet during lactation could affect various parameters in the newborn brain. These effects were different from those when the dietary caffeine level was doubled. In contrast, the effects of caffeine on brains of the dams were relatively minor.

Long-term effects of lactational zinc deficiency on bone mineral composition in rats fed a commercially modified Luecke diet

The purpose of this study was threefold: 1. to determine the long-term effects of interactions between lactational zinc deficiency and gender on bone mineral composition in repleted rat offspring, 2. to determine the nutritional efficacy of the second of two commercially designed, modified Luecke diets (ML2) during the gestational and lactational stress, and 3. determine the ultratrace element contents of Ralston Rodent Laboratory Chow #5001. The ML2 basal diet, based on dextrose, sprayed egg white, and corn oil contained 0.420 micrograms Zn/g, was supplemented with Zn (as zinc acetate) at 0 (diet 0ML2) or 30 (diet 30ML2) micrograms/g, and was mixed and pelleted commercially. All rat dams were fed the 30ML2 diet ad libitum during gestation. Beginning at parturition, the dams were fed either the 1. 0ML2, 2. 30ML2 (food restricted), or 3. 30ML2 (ad libitum) diets. All pups were fed the 30ML2 diet ad libitum from 23 to 40 d of age. From d 40 to 150, all pups were fed Ralston Rodent Laboratory Chow. The 30ML2 diet was found to be nutritionally efficacious; litter size and pup growth were normal and pup mortality was only 1.2%. Pups (ZD) with access to the 0ML2 diet until 23 d of age and nursed by dams fed the 0ML2 diet, when compared to pups (PF) fed restricted amounts of the 30ML2 diet, exhibited increased mortality and decreased concentrations of tibial zinc but no change in growth. Inadequate zinc nutriture during infancy, despite postlactational zinc repletion, induced imbalances in adult bone mineral metabolism. Thus, at 150 d of age, the ZD pups exhibited increased levels of bone P and Mg and decreased concentrations of K as compared to the PF pups.

Depletion of liver and esophageal epithelium vitamin A after chronic moderate ethanol consumption in rats: inverse relation to zinc nutriture

This study was designed to determine whether chronic moderate ethanol ingestion alters the levels of vitamin A of liver and esophageal epithelium and if this is dependent on zinc nutriture. Forty male Sprague-Dawley 4-week-old rats were divided into five groups: zinc-deficient (0.9 ppm), ethanol-fed; zinc-deficient; zinc-adequate (25 ppm); zinc-adequate (25 ppm), ethanol-fed; and zinc-supplemented (50 ppm), ethanol-fed. All rats received liquid Lieber-DeCarli diet containing 4,000 IU per liter of vitamin A for 5 weeks. Zinc-deficient, ethanol-fed rats and zinc-adequate, ethanol-fed rats and zinc-supplemented, ethanol-fed rats received 15.5% of the caloric intake as ethanol while zinc-deficient and zinc-adequate rats received isocaloric amounts of maltose dextrin. All groups were pair-fed to zinc-deficient, ethanol-fed rats. In addition, a group of eight rats designated as weight-restricted controls were fed a diet similar to the one given to zinc-adequate rats but in the amount to obtain a final weight as in the zinc-deficient group. After 35 days, the liver histology was normal in all rats, and no fat accumulation was noted. Hepatic vitamin A concentration was significantly decreased in zinc-adequate, ethanol-fed rats (41 +/- 10 micrograms per gm) and further in zinc-supplemented, ethanol-fed rats (12 +/- 5 micrograms per gm) as compared to controls (137 +/- 49). A highly significant negative correlation between serum zinc and liver vitamin A was found in ethanol-fed animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental zinc deficiency in guinea-pigs: biochemical changes

1. Zinc deficiency was produced experimentally in guinea-pigs fed on a diet containing 1.25 mg Zn/kg diet over a period of 60 d. In addition, the response of the Zn-deficient (ZnD) animals to Zn supplementation was studied for 15 d. 2. In the ZnD group a significant reduction was found in serum Zn and protein concentrations and in alkaline phosphatase (EC 3.1.3.1; AP) activity from day 24 onwards. 3. Paper electrophoretic studies on serum revealed a significant decrease in relative values, as well as absolute values, of albumin and gamma-globulin and an increase in beta-globulin. 4. Albumin:globulin increased on day 24 but decreased significantly from day 48 onwards. 5. The kidney and testis of the ZnD group showed a reduction in Zn and protein contents, and AP activity. 6. Zn supplementation of the previously ZnD group resulted in marked although incomplete improvement in the biochemical indices studied.

Role of zinc deficiency in carcinogenesis

Zinc is a trace element required for the growth of normal and neoplastic tissues in a variety of species. Zinc deficiency is associated with alterations in the activity of zinc-dependent enzymes essential for cell replication. Dietary zinc deficiency also increases the incidence of certain tumors while decreasing the incidence of others. The mechanism by which zinc deficiency alters carcinogenesis is not fully understood. Among those tumors whose incidence is increased by dietary zinc deficiency are carcinomas induced by dialkylnitrosamines. This class of carcinogens requires microsomal cytochrome P-450 activation to be mutagenic. Zinc deficiency is known to increase the cytochrome P-450-dependent metabolism of methylbenzylnitrosamine (MBN), an esophageal carcinogen of this class. Examination of the kinetics of this reaction reveals zinc to be a direct noncompetitive inhibitor of the microsomal metabolism of MBN. Thus the lower rate of MBN metabolism by zinc-adequate versus zinc-deficient microsomes may be due to normal tissue zinc acting as a noncompetitive inhibitor of cytochrome P-450 activity in vivo. This effect of zinc on carcinogen metabolism may explain the increased incidence of nitrosamine-induced carcinomas observed with dietary zinc deficiency.

Heterogeneous nature of alkaline phosphatase from rat liver

1. Alkaline phosphatase from rat liver was separated into tow components by gel filtration. 2. Both components had the same temperature and pH optima, were inhibited by high concentrations of urea and had the same activity towards hydrolysis of phenyl disodium phosphate and p-nitrophenyl phosphate. 3. They differed in electrophoretic mobility, sensitivity to inactivation by heat and digestion by neuraminidase, response to low concentrations of urea, and catalytic activity with sodium pyrophosphate and sodium phytate.

[Mechanism of lipid inhibitory effect on intestinal fucosyl-transferase in the rat]

High-fat diets decrease microsomic and soluble fucosyl-transferase activities in rat intestinal mucosa. This inhibition is not due to qualitative (pHi) or quantitative (relative activities) changes ion three isoenzymes, nor is it caused by alterations in the kinetic behaviour of these enzymes (Km, V). It is also not due to a direct effect of the fatty acids on the enzyme activities. It seems reasonable to suggest that a decreased biosynthesis of the fucosyl-transferase occurs as a result of the high-fat diets.