Biochemical mechanisms on species differences in gastric carcinogenesis

The biochemical denitrosation of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in tissues from four strains of rat, inbred Buffalo, Lewis, B-N, and the random-bred Sprague-Dawley, with different sensitivities to MNNG-induced gastric carcinomas was investigated as a possible explanation for the species/strain differences in MNNG-induced carcinogenesis. An analytical HPLC method was developed to assay denitrosation of MNNG to N-methyl-N'-nitroguanidine (MNG) by cytosolic, microsomal, mitochondrial, and nuclear cell fractions. All the activity was contained in the microsomal and cytosolic fractions, with the major portion occurring in the cytosol. The activity in both fractions was NADPH-dependent, but denitrosation was not reduced by inhibitors of the cytochrome P-450 system. Denitrosation of MNNG post-mitochondrial supernatant (S9) fractions from liver, glandular stomach mucosa, and duodenal mucosa of the four rat strains was determined. In all strains, denitrosation activities were highest in liver. Comparisons between the three strains most sensitive to MNNG-induced gastric carcinogenesis indicated no large differences for any tissue. However, Buffalo, the most resistant strain, did have a higher level of denitrosating activity in all three tissues, which is consistent with the hypothesis that higher levels of detoxifying enzymes may lead to a decreased incidence of tumors. On the other hand, denitrosation accounts for less than 3% of the MNNG that disappears during the incubation period so that the relevance of denitrosation as a mechanism in strain-specific sensitivity to MNNG-induced gastric carcinoma requires additional studies.

Differentiation of myoblast cell lines and biological methylation: 3-deazaadenosine stimulates formation of multinucleated myofibers

Treatment of myoblast cell lines with 3-deazaadenosine stimulates differentiation into myofibers. Myoblast clone L5/ 3B5 , which does not form myofibers after 6 days in fusion medium, was stimulated to form myofibers after 5 days of culture in fusion medium containing 50 microM 3-deazaadenosine. Myoblast clone L5/ 3C4 , which normally begins to form myofibers after 4 days in fusion medium, was stimulated by 50 microM 3-deazaadenosine to form myofibers after 3 days in culture and the extent of fusion was also increased. In the presence of 100 microM homocysteine thiolactone, the concentration of 3-deazaadenosine that stimulated maximal fusion was reduced by a factor of 10, from 50 microM to 5 microM 3-deazaadenosine. Stimulation of myofiber formation by 3-deazaadenosine suggests a requirement for one or more methylation reactions in myoblast differentiation and the potentiation by homocysteine thiolactone indicates that myofiber formation is specifically stimulated by an intracellular accumulation of 3-deazaadenosylhomocysteine.

A study of a Caucasian family with variant von Willebrand's disease in association with vascular telangiectasia and haemoglobinopathy

A family was identified which carries multi-haematological disorders including Type IIA von Willebrand's disease, vascular telangiectasia, and a haemoglobinopathy (haemoglobin S trait). In the affected individuals, the von Willebrand's disease varies in its expression from an asymptomatic form to a severe form especially in those patients with telangiectasia. Some patients have vascular telangiectasia in the mucous membranes of the mouth and lips. In two patients endoscopy disclosed telangiectasia in the mucous membranes of the gastrointestinal tract. All of the patients who had telangiectasia also had von Willebrand's disease. An incidental finding was the presence of an abnormal haemoglobin (haemoglobin S) in some family members. The pattern of inheritance of the haemoglobinopathy was unrelated to the inheritance pattern of von Willebrand's disease. The presence of haemoglobin S did not interfere with the aggregation of platelets in response to ristocetin.

Aerosol lead and associated elements in Beijing, China

The relative importance of local and regional sources of lead and associated elements in fine and coarse aerosol particles of an urban atmosphere was assessed by means of a two-day study, July 20 and 30, 1980 in Beijing, China. Five near-ground locations were selected for aerosol sampling by cascade impactors and elemental analysis by proton induced X-ray emission (PIXE): the imperial palace courtyard, a park, near two streets, and a mid-street traffic island. These sites, ranked in order of increasing traffic intensity and fugitive surface dust, showed that concentrations of major dust constitutents, represented by coarse particle (>2 μm diameter) Si, Al, and Ca, increased correspondingly. Pb, as well as Zn, As, and Cu, were present mainly in fine (<2 μm) particles; their concentrations were unrelated to traffic, indicating they resulted mainly from regional combustion or other sources. However, these elements also were present in coarse particles at concentrations that varied with the major dust elements and were relatively enriched, compared to average earth crust rock material, by factors of more than 100 (Pb), 50 (Zn), and 10 (Cu). Nonurban Beijing shows much smaller coarse aerosol enrichments of Pb, Zn, and Cu, indicating urban contamination of surface dust. Published data from St. Louis, USA show both fine and coarse aerosol Pb and Zn. Compared with Beijing, fine and coarse concentrations in St. Louis are similar for Pb, but lower for Zn, Ca, and Fe. Both Pb and Zn are enriched relative to earth crust composition to a greater degree in St. Louis than Beijing in both fine and coarse particle size ranges. The results suggest that heavy metals from combustion occur in the air as fine particles and, after deposition on the surface, as reentrained coarse particles of fugitive dust. Both many contribute to human exposures of these heavy metals.

Carbamazepine diminishes the sensitivity of the plasma arginine vasopressin response to osmotic stimulation

Carbamazepine, a drug used to treat manic-depressive illness, has been reported to possess antidiuretic properties, but its effects on arginine vasopressin (AVP) secretion are controversial. Consequently, we examined plasma AVP secretion during hypertonic (5%) saline infusion in seven manic-depressive patients while on placebo and after 3-5 weeks of carbamazepine treatment. We also measured carbamazepine's effects on basal levels of the hormone in cerebrospinal fluid. Carbamazepine significantly reduced the sensitivity of the plasma AVP response to osmotic stimulation without affecting the osmotic threshold for AVP secretion. Moreover, carbamazepine did not affect baseline weight, plasma osmolality, plasma sodium, urine output, plasma AVP, or cerebrospinal fluid AVP. Although the functional significance of these findings remain to be fully determined, the fact that carbamazepine significantly reduced AVP secretion without inducing diuresis supports previous suggestions that carbamazepine enhances renal responsivity to available AVP. In addition, since carbamazepine failed to affect the osmotic threshold, the reported cases of carbamazepine-induced inappropriate AVP secretion and water intoxication must be very uncommon and probably represent idiosyncratic responses.

Drug interactions I: detection of inorganic nitrite in organic nitrate esters under acidic conditions simulating the human stomach

Both unformulated (bulk) and formulated (drugs) organic nitrate esters (isosorbide dinitrate, nitroglycerin, and pentaerythritol tetranitrate) were studied in the presence and absence of hydrochloric acid to determine if they could be sources of nitrite (and therefore lead to nitrosamine formation) under acidic conditions similar to those found in the stomach. The presence and generation of nitrite ion was detected by a modification of the Griess reaction. Bulk isosorbide dinitrate and nitroglycerin were found to be contaminated with 13.8-121.4 mumoles of inorganic nitrite per mole of nitrate ester. In addition, in the presence of hydrochloric acid, these preparations generated 0.52-1.18 mumoles of inorganic nitrite/mole of nitrate ester/min. Unformulated nitroglycerin generated nitrite at a rate roughly twice that of isosorbide dinitrate. In contrast, no evidence for nitrite contamination or generation by pentaerythritol tetranitrate was found. Tablets and capsules of isosorbide dinitrate contained approximately 27-216 mumoles of nitrite/mole of nitrate ester and, in the presence of hydrochloric acid, generated an average of 0.55 mumole nitrite/min. For isosorbide dinitrate, this rate was similar for bulk and formulated drug. In comparison to isosorbide dinitrate, the amount of nitrite initially present in tablets and capsules of nitroglycerin varied more widely (approximately 25-2290 mumoles nitrite/mole of nitrate ester), and in this case nitrite was generated at higher rates than unformulated drug averaging approximately 4.7 mumoles nitrite/mole of nitrate ester/min. Contrary to a literature report, we found that nitrate ion is not reduced to nitrite by hydrochloric acid (pH 1-3).(ABSTRACT TRUNCATED AT 250 WORDS)

Hemifacial spasm: treatment by microsurgical facial nerve decompression

The literature on hemifacial spasm and its surgical therapy is reviewed, and the authors' experiences with 20 patients are described. Vascular cross compression of the facial nerve adjacent to the brain stem is seen in 90% of the surgical patients. Mobilizing the offending vessel will cure or significantly improve approximately 80% of the patients. Complications occur in 25% of the patients and usually involve decreased hearing or facial weakness. Mortality is virtually zero, and this operation is vastly superior to any other medical or surgical therapy for hemifacial spasm. The pathophysiology is not yet understood.

Drug interactions. II. Formation of nitrosamines from therapeutic drugs. Properties and kinetics of the formation of N-nitrosopropranolol from nitrite and the secondary amine propranolol hydrochloride

In the presence of hydrochloric acid, nitrosamines may be generated from amines and nitrite. Most nitrosamines are carcinogens and many commonly used drugs contain potentially nitrosatable amine groups. Beta-adrenergic blockers, which have such amine groups, are widely prescribed and are often ingested for the lifetime of the patients, but their safety with respect to the intragastric formation of nitrosamines has not been established. The studies in this and the following report were designed to assess the potential risk posed by the endogenous formation of a nitrosamine in the stomach to individuals receiving longterm treatment with propranolol hydrochloride. The putative nitrosamine, N-nitrosopropranolol (NNP), was synthesized and its stability was examined under various experimental conditions. A high-pressure liquid chromatographic method was developed which detects a minimum of 7 X 10(-11) mol of NNP in the presence of large quantities of unreacted drug. Preparations of propranolol hydrochloride were found to contain several non-nitrosamine contaminants, which were removed before kinetic studies. At 37 degrees C, in solutions of HCl within the pH range found in the stomach, the optimum pH for the formation of NNP was 3. The yield of NNP increased linearly as incubation time and concentration of propranolol increased and exponentially as the concentration of nitrite was raised. Under optimal conditions in hydrochloric acid, the minimum concentration of nitrite required for the production of detectable amounts of NNP was 10(-5) M.

Drug interactions. III. Formation of nitrosamines from therapeutic drugs. Formation, mutagenic properties and safety assessment of propranolol hydrochloride with respect to the intragastric formation of N-nitrosopropranolol under conditions found in patients

In the preceding report, the kinetics of formation of N-nitrosopropranolol (NNP) from propranolol and inorganic nitrite were determined in solutions of hydrochloric acid over the range of pH similar to that found in the human stomach. In this communication, NNP formation was examined in human gastric juice and in the presence of organic nitrate ester vasodilator drugs. In comparison to HCl solutions, equivalent concentrations of propranolol and nitrite produced similar amounts of NNP in gastric juice; however, the yield increased as the pH was lowered and the kinetics of nitrosamine formation were different. Endogenous nitrite concentrations in 22 samples of human gastric juice were below the minimum concentration (10(-5) M) required for production of detectable levels of NNP. Maximal therapeutic dosages of propranolol (10(-2) M) incubated with isosorbide dinitrate (3,4-6.8 X 10(-3) M) or nitroglycerin (8.6 X 10(-4) M) also failed to produce NNP. However, NNP formed adventitiously during the concentration of aqueous and methylene chloride solutions that contained propranolol and organic nitrates, underscoring the importance of avoiding artifactual formation of nitrosamines. Furthermore, synthetic NNP was not mutagenic in either the Ames tester strains (TA92, TA98, TA100, TA1535, TA1537 and TA1538) or the hepatocyte-mediated mammalian cell mutagenesis assay. We conclude that NNP is unlikely to form in the stomach under conditions normally present in patients. Moreover, even if NNP formed under exceptional circumstances, this compound is unlikely to be a carcinogen. With respect to the potential formation of nitrosamines during drug dissolution in the stomach, long-term therapy with propranolol hydrochloride appears to be safe.

Sexual experience and plasma testosterone levels in male veterans after spinal cord injury

Fifty men with spinal cord injuries (SCI) were asked to complete a questionnaire concerning their sexuality before and after injury. Medical examination confirmed the location and completeness of the injury and extracted information about genitourologic status. The respondents rated sexuality highly as a concern in living, and a wide variety of sexual techniques were reported. A marked decrease in sexual activity, satisfaction, and feelings of sexual adequacy was reported after injury, as compared to retrospective "before injury" responses, lack of opportunity being reported as causative by 66% of the subjects and insufficient personal satisfaction by 59%. Seventy-five percent of the subjects experienced sexual arousal from genital stimulation, and several methods of eliciting erection were cited. Orgasm was described by a variety of terms. Significant differences were found between quadriplegic and paraplegic patients in answers to several items, though there was generally no difference between cervical and thoracic groups, which were more specifically broken down with respect to motor or sensory/complete or incomplete lesions. Plasma testosterone levels were found to fall well within the normal adult male range, as were levels of free testosterone and serum sex binding protein. The resulting information demonstrated more sexual concern among men with SCI than the literature previously indicated.

An extraterrestrial habitat on Earth: the algal mat of Don Juan [correction of Jaun] Pond

On the edge of Don Juan Pond in the Wright Valley of Antarctica lies a mat of mineral and detritus cemented by organic matter. In spite of a CaCl2 concentration of about 33% (w/v), the mat contains Oscillatoria and other cyanobacteria, unicellular forms, colonial forms rich in carotenoids, and diatoms. Bacteria are rare; fungal filaments are not. Oscillatoria showed motility but only at temperatures <10 degrees C. Acetone extracts of the mat and nearby muds yielded visible spectra similar to those of laboratory grown O. sancta, with 50- to 70-fold molar ratio of chlorophyll a to b. Although rare, tardigrades were also found. The algal mat had enzymatic activities characteristic of peroxidase, catalase, dehydrogenase, and amylase. Cellulose, chitin, protein, lipid and ATP were present. Previously, algae in the Wright Valley have been described in melt water, not in the brine itself. Wright Valley has been used as a near sterile Martian model. It obviously contains an array of hardy terrestrial organisms.

Aspects of treatment at the Zhejiang Medical College, China. An operation for recurrent pigment gallstones--subcutaneous choledocho-jejunostomy

In China recurrent pigment gall stones are common and may cause acute obstructive suppurative cholangitis. A partial solution to this problem is the creation of a new anatomical arrangement whereby recurrent gall stones can be easily and safely removed.

Aspects of treatment at the Zhejiang Medical College, China. Pedicle auto-transplantation of the adrenal gland in the treatment of Cushing's syndrome

Cushing's syndrome due to hyperplasia of the adrenal cortex can be treated by total adrenalectomy with one of the adrenal glands transplanted with a vascular pedicle to an easily accessible site. If the symptoms persist or recur after the operation, superfluous transplanted gland can be partially resected under local anaesthesia.

Cone-mirror resonator Q-switched operation

Giant pulse Q-switched operation of a cone-mirror resonator has been performed. Measurement of the conventional output energy vs resonator length was obtained. The damage level of the dye cell's location is discussed. With some optimization and careful engineering, cone-mirror resonators have valuable advantages.

Decreased antithrombin III level associated with failure of anticoagulation

A 67-year-old man with adenocarcinoma of the colon had recurrent pulmonary emboli. The patient's level of serum antithrombin III was found to be below normal. Heparin therapy led to further reduction, resulting in failure of adequate anticoagulation. The patient subsequently died of massive pulmonary emboli despite heparin therapy. We believe the antithrombin III level should be routinely determined for patients receiving heparin therapy.

Effects of dietary selenium and vitamin E on covalent binding of aflatoxin to chick liver cell macromolecules

Day-old single comb white Leghorn chicks of both sexes maternally depleted in selenium (Se) and vitamin E (VE) were fed a low Se and VE-free semipurified basal diet or that diet supplemented with graded levels of Se (0.2 - 20.0 ppm as Na2SeO3) of VE (100 IU/g as all-rac-alpha-tocopheryl acetate), or both. At 14 days of age, chicks were given 1 mg/kg [3H] aflatoxin B1 (AFB1) i.p. and killed either 2 or 24 hours later. Covalent binding of AFB1 to liver DNA and RNA in chicks fed the basal diet was significantly greater than in chicks supplemented with Se or VE, or both. Phenobarbital treatment prior to administration of AFB1 decreased adduct formation in most groups, and abolished differences in adduct formation due to diet. These results suggest that combined Se-VE deficiency enhances activation or inhibits detoxification of AFB1 in vivo.

Effects of dietary selenium and vitamin E on hepatic mixed-function oxidase activities and in vivo covalent binding of aflatoxin B1 in rats

Male weanling fischer-344 rats were fed a selenium (Se)-vitamin E (VE) deficient Torula yeast basal diet or that diet supplemented with a graded levels of SE (0.2-6.0 ppm as Na2SeO3) or VE (100 iu/kg as all-rac-2-tocopheryl acetate), or both, for 4 or 6 weeks. Se deficiency and excess (6.0 ppm) markedly depressed in vivo covalent binding of aflatoxin (AFB1) to macromolecules in livers of rats killed 2 hours after an i.p. dose of 1 mg/kg tritiated AFB1. VE supplementation had no effect. Prior phenobarbital (PB) treatment generally decreased adducts without changing diet-related trends. Some hepatic enzyme capabilities were also measured. Cytochrome b5 content and cytochrome c reductase activity were unaffected by diet. VE increased cytochrome P-450 content, ethylmorphine N-demethylase and benz(alpha)pyrene hydroxylase activities; all these were unaffected by Se levels. Se deficiency and excess (but not VE deficiency) increased glucuronyl transferase. PB induction affected all diet groups and was more in agreement with MFO activity than transferase. Adduct formation was more consistently related to transferase activity than to MFO activities. The contrasting effects of SE and VE on AFB1 adducts in rats and chicks are discussed.

Bilirubin interactions with phospholipid components of lung surfactant

This work examines the dynamic surface pressure-area behavior of films of unconjugated bilirubin spread from chloroform solution at 22 degrees C on 0.15 M NaCl and buffered phosphate subphases. Film behavior is examined at pH 5.5, 7.4 and 8.0. The interactions of bilirubin in mixed films with dipalmitoyl phosphatidylcholine and with 9:1 dipalmitoyl phosphatidylcholine:dioleolyl phosphatidylcholine are examined at similar temperature and pH values. It is found that unconjugated bilirubin modifies the dynamic surface pressure-area behavior of phospholipid films in both the high and low surface pressure regimes, with bilirubin exerting its greatest effect at low pH where its subphase solubility is low. Because many premature infants suffering from the Respiratory Distress Syndrome (RDS) have accompanying hyperbilirubinemia, with possible bilirubin transport to the alveolar space, the interactions of bilirubin with phospholipid films are discussed in terms of potential effects on pulmonary surfactant in vivo.

Variant von Willebrand's disease and pregnancy

The clinical course and coagulation profile of a pregnant patient with variant von Willebrand's disease were followed from the second trimester through puerperium. The clinical course was characterized by a normal delivery and absence of abnormal bleeding or need for replacement therapy. The coagulation profile demonstrated an increase in factor VIII procoagulant activity, factor-VIII-related antigen, and platelet aggregation activity in response to ristocetin prior to delivery. Postpartum, these factors decreased to prepregnancy values with distinctly different patterns. Factor VIII procoagulant activity continued to rise for 5 days after delivery and then decreased with a half-life of approximately 6 days. Factor-VIII-related antigen began to decrease just prior to delivery, displaying a half-life or approximately 6 days. Ristocetin cofactor activity, however, dropped immediately postpartum and displayed a half-life of approximately 6 hr. The ristocetin cofactor activity was associated with factor-VIII-related antigen, which displayed a significantly smaller molecular weight than does normal factor-VIII-related antigen. Larger aggregates of factor-VIII-related antigen. Larger aggregates of factor-VIII-related antigen did not appear during the pregnancy, and ristocetin cofactor activity could not be demonstrated in fragments of less than 0,8 x 10(6).

Expression of storage-protein genes during soybean seed development

Mature seeds of Glycine max (L.) Merr. contain two major storage proteins, a glycosylated 7S protein (conglycinin) and a non-glycosylated 11S protein (glycinin). Accumulation of these proteins and their mRNAs during seed development in cv. Provar was studied by SDS polyacrylamide gel electrophoresis and by "Northern" (DNA-RNA) hybridization. The 11S acidic and basic subunits and the 7S α' and α subunits began to accumulate 18-20 d after pollination, shortly after the termination of cell division in developing cotyledons, whereas the 7S β and 11S A-4 subunits were not detected until one to two weeks later, during the maturation phase of development. Messenger RNAs for 7S and 11S proteins were first detected 14-18 d after pollination, several days before the accumulation of storage proteins. Extracts from embryonic axes contained reduced levels of the 7S α subunit, very little 11S protein, no detectable 7S β or 11S A-4 subunits, and an additional 7S subunit not found in cotyledons. Soybean axes and cotyledons therefore differ in their synthesis of seed storage proteins.

Dihydromevinolin, a potent hypocholesterolemic metabolite produced by Aspergillus terreus

A new, potent hypocholesterolemic agent is produced by cultures of Aspergillus terreus. The isolation of the compound and its characterization as 4a,5-dihydromevinolin containing a trans-fused octahydro-naphthalene system are described. Comparative data for dihydromevinolin and mevinolin in three biological assays are given: in vitro inhibition of HMG-CoA reductase, inhibition of sterol synthesis in cell cultures, and inhibition of cholesterol synthesis in vivo in rats.

Subunit characterization of lens intermediate filaments

The intermediate filaments from the bovine ocular lens can be fractionated into three 54000 dalton polypeptides (alpha, beta and gamma) which are present in equimolar quantities and differ from one another with respect to isoelectric point, two-dimensional peptide map pattern and total amino acid composition. The polypeptides, for which the name lentin is proposed, were purified from the 8 M urea extract of the water-insoluble residue of the cortical fiber cells by ion-exchange chromatography on DE- and CM-cellulose. The regeneration of native-appearance filaments from each purified fraction, or combinations thereof, definitively established the three polypeptides as the subunit species. Additionally, small diameter 'protofilaments' were regenerated when one or two fractions were utilized, but not when all three fractions were combined. This, together with the fact that the stoichiometric yield of the three species was invariably equimolar, suggests that alpha, beta, and gamma may be distinct entities not related by artifactual interconversion.

Mevinolin: a highly potent competitive inhibitor of hydroxymethylglutaryl-coenzyme A reductase and a cholesterol-lowering agent

Mevinolin, a fungal metabolite, was isolated from cultures of Aspergillus terreus. The structure and absolute configuration of mevinolini and its open acid form, mevinolinic acid, were determined by a combination of physical techniques. Mevinolin was shown to be 1,2,6,7,8,8a-hexahydro-beta, delta-dihydroxy-2,6-dimethyl-8-(2-methyl-1-oxobutoxy)-1-naphthalene-hepatanoic acid delta-lactone. Mevinolin in the hydroxy-acid form, mevinolinic acid, is a potent competitive inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase [mevalonate: NADP+ oxidoreductase (CoA-acylating), EC 1.1.1.34]; its Ki of 0.6 nM can be compared to 1.4 nM for the hydroxy acid form of the previously described related inhibitor, ML-236B (compactin, 6-demethylmevinolin). In the rat, orally administered sodium mevinolinate was an active inhibitor of cholesterol synthesis in an acute assay (50% inhibitory dose = 46 microgram/kg). Furthermore, it was shown that mevinolin was an orally active cholesterol-lowering agent in the dog. Treatment of dogs for 3 weeks with mevinolin at 8 mg/kg per day resulted in a 29.3 +/- 2.5% lowering of plasma cholesterol.

Studies on the relations of selenium and Keshan disease

Keshan disease is an endemic cardiomyopathy of unknown cause in The People's Republic of China that occurs most frequently in children under 15 years of age and women of child-bearing age. Studies of children 1-9 years old in Mianing County of Sichuan Province have indicated that Keshan disease is a selenium responsive condition. Incidence rates of 9.5-13.5/1000 in 1974-1975 were reduced to 1-2/1000 in children treated with a tablet weekly of 0.5-1 mg sodium selenite. During 1974-1977, only 21 cases of the disease occurred in 36,603 treated children, compared with 106 cases in 9430 untreated children, of whom 53 died and 5 still have insufficient heart function. Occurrence of the disease was invariably associated with a lower selenium content of cereals, and of hair (less than 0.12 ppm Se) in residents from affected, compared with non-affected, areas. The dose relationship between selenium and regional characteristics of Keshan disease suggests that it is probably a biogeochemical disease; other etiological factors have also been considered.

Significance of "high" acid phosphatase activity in the serum of normal children

Serum acid phosphatase activity in normal children (newborn to 18 years) is several fold that in normal adults. Activity is age-related but not sex-related. The isoenzyme pattern in children is similar to that in adults and contains no prostatic fraction. Quantitatively, most of the enzyme activity in the serum of children is tartrate-resistant and correlates well with heat-labile fractions of alkaline phosphatase activity in serum, suggesting that the source of the higher acid phosphatase activity in children is bone. Significant tartrate-resistant acid phosphatase activity was demonstrated in the giant cells in three patients with giant-cell tumors, but not in the "osteoblasts" in six patients with osteogenic sarcomas and many other normal or abnormal tissues. This work suggests that the higher enzyme activity in the serum of children represents a normal physiological phenomenon resulting from their greater osteoclastic activity.

Significance of "high" acid phosphatase activity in the serum of normal children

Serum acid phosphatase activity in normal children (newborn to 18 years) is several fold that in normal adults. Activity is age-related but not sex-related. The isoenzyme pattern in children is similar to that in adults and contains no prostatic fraction. Quantitatively, most of the enzyme activity in the serum of children is tartrate-resistant and correlates well with heat-labile fractions of alkaline phosphatase activity in serum, suggesting that the source of the higher acid phosphatase activity in children is bone. Significant tartrate-resistant acid phosphatase activity was demonstrated in the giant cells in three patients with giant-cell tumors, but not in the "osteoblasts" in six patients with osteogenic sarcomas and many other normal or abnormal tissues. This work suggests that the higher enzyme activity in the serum of children represents a normal physiological phenomenon resulting from their greater osteoclastic activity.