Significance of magnesium and zinc metabolism in the surgical patient. II. Zinc

Immune and metabolic responses in early and late sepsis during mild dietary zinc restriction

BACKGROUND

Mild dietary zinc (Zn) deficiency is widespread in human populations, but its influence on recovery after acute illness is poorly understood. In a mouse model of abdominal sepsis (cecal ligation puncture), systemic immune responses and liver metabolism were monitored in early (24 h) and late (5 d) phases, under control conditions and during mild dietary Zn restriction.

METHODS

Mice were fed diets adequate or marginally deficient (ZM) in Zn (30 versus 10 mg zinc/kg diet) for 4 wk, before undergoing laparotomy alone (nonseptic control) or cecal ligation puncture (septic).

RESULTS

Among nonseptic mice, the ZM state was not associated with differences in inflammation or metabolic responses. Among septic mice, mortality did not differ between the zinc adequate and ZM groups. In the early phase, the ZM state amplified increases in plasma interleukin (IL) 6, tumor necrosis factor alpha, and IL-10, while dampening the interferon gamma response. In the late phase, subtle but significant ZM-associated increases were observed in plasma IL-5 and interferon gamma levels and hepatic protein synthesis, the latter of which appeared to be mammalian target of rapamycin independent and was associated with increased hepatic tumor necrosis factor alpha messenger RNA content.

CONCLUSIONS

Without increasing mortality, the ZM state is associated with a more disordered acute systemic inflammatory response and persistence or enhancement of acute phase responses within the liver parenchyma.

Prevalence of systemic inflammation and micronutrient imbalance in patients with complex abdominal hernias

OBJECTIVE

To determine the prevalence of low-grade inflammation, micronutrient imbalances and associated clinical profiles in patients being evaluated for complex abdominal hernia repair.

METHODS

Review of 127 consecutive adult patients for evaluation of complex ventral hernias from January 2012 to March 2013. Records were analyzed to determine the prevalence and correlations of clinical risk factors, attributes of hernias identified by computerized tomography, and laboratory indices of metabolism, inflammation and micronutrient imbalances.

RESULTS

Strong correlations (p < 0.001) were established for body mass index (BMI) with volume of hernia content and C-reactive protein (CRP) level. CRP levels correlated strongly with red cell distribution width and inversely with zinc (p < 0.01). Evidence of micronutrient imbalance (abnormal zinc or red cell distribution width [RDW]) was observed in 48%.

CONCLUSIONS

In this comorbidity-rich population with known variability in surgical outcomes, the prevalence of chronic inflammation and micronutrient deficiency are high enough to warrant systemic preoperative evaluation given their possible effect on wound healing and convalescence. Simple repletion is unlikely to improve outcomes without attention to the biological stresses that are associated with micronutrient imbalance.

Hemorrhagic shock and surgical stress alter distribution of labile zinc within high- and low-molecular-weight plasma fractions

Zinc ions (Zn) are essential for tissue repair following injury or stress. We hypothesize that during such stresses Zn is redistributed to labile pools in plasma components. Here we tested this hypothesis using a novel assay to monitor labile Zn in plasma in hemorrhagic shock. Adult rats in the shock group (S group) underwent hemorrhage and resuscitation. Blood samples were drawn at baseline and at 1, 4, and 24 h. The surgical control group (SC group) was anesthetized and instrumented, but not bled. Albumin, total Zn, and labile Zn levels were assayed in plasma. Binding capacity for Zn was assessed in high- and low-molecular-weight pools. Significant decreases in total Zn were observed by 24 h, in both S and SC groups. Albumin levels were significantly reduced in the S group at 1 and 4 h but restored at 24 h; significant changes were not observed in other groups. In whole plasma, labile Zn levels were stable initially in the S and SC groups, but declined at 24 h. In the high-molecular-weight pool, marked and significant impairment of binding was noted throughout all time periods following the shock period in the S group. Such changes were observed in the SC group of less intensity and duration. These experiments suggest that shock alters affinity of plasma proteins for Zn, promoting delivery to peripheral tissues during periods of increased Zn utilization.

Mineral deficiency in patients who have undergone gastrectomy

OBJECTIVE

We investigated the nature of nutritional deficiencies that arose in gastrectomy patients by comparing mineral absorption in patients with total and subtotal gastrectomies before and after operation.

METHODS

Levels of nutritional, micro, and toxic minerals were measured in a subject group of 20 patients with gastric cancer. Patients were grouped according to total versus subtotal gastrectomy. Hair tissue was collected 3 mo before and after operation from each patient. Tissue was analyzed by atomic absorption spectroscopy for levels of various minerals. Mineral ratios were computed to display changes in mineral levels, and results were statistically analyzed with SPSS 10.0 to obtain a measurement distribution. The t test was used to determine any significant difference between patients before and after operation.

RESULTS

In the preoperation test, sodium, potassium and iron levels were higher than normal, whereas boron and molybdenum levels were lower than normal. Although sodium levels decreased significantly after surgery, molybdenum, cadmium, and lead levels increased significantly. Potassium decreased slightly in the subtotal gastrectomy group, but increased significantly in the total gastrectomy group. However, there was no change between before and after surgery for most minerals.

CONCLUSION

In the short term, gastrectomy does not seem to affect the levels of most minerals in the body. However, changes in sodium levels indicate that gastrectomy affects sodium absorbency in gastric cancer patients. Potassium levels increased significantly in patients who received total gastrectomies; this may also be an area that nutritional treatment should focus on.

Effect of Silica Exposure on Urinary Excretion of Copper and Zinc

BACKGROUND

Occupational exposure to silica could lead to renal histological alterations in the glomeruli and proximal tubules. We investigated urinary excretion of copper and zinc and its possible relationship to renal alterations and work duration among nonsmoking, silica-exposed workers.

METHODS

Thirty-six control subjects (age, 39.08 +/- 6.65 years) and 48 silica-exposed workers (age, 36.79 +/- 7.33 years) were included in the present study. The exposed workers were grouped into workers with <10 years' work duration (n = 9; age, 29.0 +/- 1.50 years) and workers with > or =10 years' work duration (n = 39; age, 38.59 +/- 6.94 years). Glomerular function was assessed by measuring urinary level of microalbumin, and proximal tubular reabsorption function was assessed by measuring urinary level of alpha1-microglobulin. Structural integrity of proximal tubules was studied by measuring urinary activity of cytosolic enzyme glutathione S-transferase (GST). Also, urinary levels of copper, zinc, and creatinine were measured.

RESULTS

All measured urinary parameters were significantly increased among silica-exposed workers compared with control subjects. A significant correlation was observed between urinary levels of each of copper and zinc with the glomerular and proximal tubular functional and structural urinary parameters as well as work duration.

CONCLUSIONS

Occupational silica exposure may lead to increased urinary loss of copper and zinc as protein-metal complex, and the urinary level of these essential trace elements may be a marker for renal dysfunction. The urinary excretion of GST may be a useful marker for proximal tubular injury.

Serum protein and zinc levels in patients with thoracic empyema

The element Zn is the metal component or activator of many important enzymes. The tissue concentrations and activities of Zn metalloenzymes direct the rate of protein and nucleic acid syntheses, thereby influencing tissue growth and reperative processes. Most of the serum Zn is normally bound to circulating proteins. Low serum Zn concentrations might result from depletion of Zn-binding proteins. Serum protein and Zn concentrations have been reported to be depressed in patients with acute and chronic diseases. We compare the serum protein and Zn values of patients with thoracic empyema (n = 20) with those of a control group (n = 20). The values obtained in the empyema group were significantly lower than those in the control group before the study. Test group administered 220 mg zinc sulfate (ZnSO4.7H2O) over 20 d and there was a significant increase in the values for serum protein and Zn after the oral administration of the zinc sulfate.

Clinical studies on zinc metabolism during total parenteral nutrition as related to zinc deficiency

In 99 adult patients receiving controlled total parenteral nutrition (TPN), a study was made on the time course of concentrations of zinc in plasma, erythrocyte and urine in relation to the development of zinc deficiency. Zinc deficiency developed in 11 cases receiving TPN solutions not containing zinc. The plasma zinc level was significantly lower at the time of onset of zinc deficiency than in normal subjects, before the procedure of TPN, or at the time of symptomatic relief achieved by administration of zinc. The erythrocyte zinc level was slightly but not significantly lower at time of onset of zinc deficiency than in normal subjects, before TPN or at time of symptomatic relief. The urinary zinc level at time of onset of zinc deficiency was significantly lower than that in normal subjects or at the time of symptomatic relief but not significantly lower than that before TPN. A comparison between patients developing and those not developing zinc deficiency within 4 wk of the outset of TPN showed that only the plasma zinc level was significantly lower in the former than the latter group. The urinary zinc level also tended to be lower, although not significantly, in the former than the latter group but varied widely. No difference was present between the groups as to the erythrocyte zinc level. Zinc deficiency developed in none of those patients who had a plasma zinc level of 50 micrograms/dl or more but in five of 10 (50%) patients with less than 50 micrograms/dl and in all three with less than 30 micrograms/dl of zinc in plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

Zinc concentration in normal and healing gingival tissues in beagle dogs

Previous studies have shown that the administration of zinc (Zn) may enhance the healing of gingival and other wounds. This study was undertaken to determine if Zn concentration ([Zn]) is increased in healing gingival tissues and if oral supplementation of Zn would result in a local increase in [Zn] within these tissues. On Day 0, biopsies were obtained from the maxillary left buccal gingiva of each of 10 beagle dogs. Gingival biopsies were taken from the healing original biopsy sites on Day 14. On Day 15, oral supplementation of Zn gluconate (250 mg/day, equivalent to 32.5 mg of elemental Zn) was begun in seven dogs. Three dogs remained as unsupplemented controls. Two weeks later (Day 28), normal gingival biopsies were obtained from the right side of the maxilla and on Day 42 final biopsies were taken from the same healing sites. In addition, serum samples were obtained on Days 0, 14, 28 and 42. All samples were analyzed for Zn content using atomic absorption spectrophotometry. The [Zn] of healing tissues was significantly higher (P less than 0.0005) than normal tissues. This was also true when healing tissues were compared to normal tissues during the Zn supplementation phase (Day 28 vs. Day 42; P less than 0.005). Zn supplementation resulted in significant increases in Zn levels in normal (Day 0 vs. Day 28; P less than 0.05) and healing tissues (Day 14 vs. Day 42; P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Serum zinc levels and urinary zinc excretion in patients with bronchogenic carcinoma. Effects of tumor resection

Low serum zinc levels and high urinary zinc excretion were found in 25 patients with bronchogenic carcinoma. Twenty of them underwent successful removal of the tumor by lobectomy or pneumonectomy; in the other 5 patients surgical exploration revealed unresectable pulmonary lesions. The latter had significantly lower serum zinc and higher urinary zinc levels than the patients in whom surgical removal of the tumor could be performed. Tumor resection was followed by restoration of serum and urinary zinc to normal. In contrast, in the inoperable patients a further decrease in serum zinc and no significant change in urinary zinc excretion were noted 15 days after thoracic exploration. In both patient groups a significant negative correlation existed between preoperatively obtained values of serum and urinary zinc. Hypozincemia in patients with bronchogenic carcinoma may result from an increase in urinary zinc losses, probably related to a decrease in zinc binding to plasma proteins. Determination of serum and urinary zinc may be useful in evaluating the prognosis of primary lung cancer.

Differential effect of surgical injury and thermal burn on zinc metabolism in man

Serum, erythrocyte and urinary zinc were serially measured during the early ten days following major surgery or thermal burns in 18 and 8 patients, respectively. Serum zinc gradually decreased and erythrocyte and urinary zinc increased during the first three postoperative or post-burn days. Thereafter, both serum and erythrocyte zinc gradually returned to preoperative levels in the patients subjected to surgery, while serum zinc continued to fall progressively despite a rapid restoration of erythrocyte zinc to control values, in the burned patients. It is suggested that in contrast to the early postoperative or post-burn hypozincemia, which may be attributed to a redistribution of zinc from plasma to tissue, continued decrease in serum zinc following thermal burns may indicate a mobilization of zinc to the burn site and eventually result in significant zinc depletion.

Plasma and urinary zinc in patients with malabsorption syndromes or hepatic cirrhosis

Plasma and urinary zinc have been measured in 19 patients with malabsorption and 21 patients with hepatic cirrhosis. The results have been compared with those of 20 control subjects and 23 patients with a variety of other diseases. The diurnal variation in plasma zinc levels has been confirmed and is of such magnitude that this must be taken into account in comparing results in groups of subjects. Plasma zinc levels, both fasting and after a meal, are significantly lower in patients with cirrhosis (71 and 60 mug/100 ml) and malabsorption (76 and 64 mug/100 ml) than in controls (97 and 81 mug/100 ml). In the patients with cirrhosis or malabsorption similar correlations exist between plasma zinc and plasma albumin, suggesting that the low plasma zinc levels may be, at least in part, dependent on the plasma albumin level. Urinary zinc excretion is increased in cirrhosis, but not in malabsorption, indicating that increased urinary loss is unlikely to explain the low plasma levels.

The effects of systemic zinc supplements on the strength of healing incised wounds in normal rats

The effect of the systemic administration of zinc sulphate (4.5 mg. Zn per day) to rats on a normal dietary intake of zinc was studied with reference to the tensile strengths of healing skin and musculofascial wounds.

In comparing control and zinc-treated groups, no significant differences in the tensile strengths of 4-day, 7-day, or 10-day wounds were demonstrated.

A new method of testing the strength of anterior abdominal wall wounds by measuring increasing intra-abdominal pressure up to bursting point is described.

Sutured incised wounds of the linea alba were of identical strength in control and zinc-treated animals after 4, 7, and 10 days.

No toxic effects were observed with the dosage of zinc used.

It is concluded that the administration of supplementary zinc has no effect on the healing of sutured, incised wounds in normal rats.