Hereditary hemolytic anemia with increased red cell adenosine deaminase (45- to 70-fold) and decreased adenosine triphosphate.

Hereditary hemolytic anemia, a dominantly transmitted disorder, has affected 12 family members spanning three generations. The concentration of adenosine triphosphate in the red cells was about half that of comparably reticulocyte-rich blood. Since adenosine deaminase and adenosine kinase compete for a common substrate, the greatly increased activity of the former may interfere with nucleotide salvage via the latter.

Effects of low-level lead exposure on pyrimidine 5'-nucleotidase and other erythrocyte enzymes. Possible role of pyrimidine 5'-nucleotidase in the pathogenesis of lead-induced anemia.

Similarities between lead-induced anemia and a new hereditary erythorenzymopathy involving pyrimidine-specific 5'-nucleotidase prompted studies of the effects of lead on this and other erythrocyte enzymes. In vitro incubations of normal mature erythrocytes demonstrated that significant inhibition of pyrimidine 5'-nucleotidase occurred in the presence of lead at concentrations that had minimal effects on many other erythrocyte enzymes assayed simultaneously. Similarly, subjects with chronic lead intoxication secondary to industrial exposure exhibited substantial and consistent impairment of erythrocyte pyrimidine-5'-nucleotidase activity. Results suggest that lead-induced deficiency of this enzyme in maturing erythroid elements could, if sufficiently severe, result in induction of basophilic stippling and premature erythrocyte hemolysis analogous to that encountered in the genetically induced enzyme-deficiency syndrome.

Lead poisoning. Further observations on erythrocyte pyrimidine-nucleotidase deficiency and intracellular accumulation of pyrimidine nucleotides.

Pyrimidine nucleotides, detectable in normal erythrocytes only in trace quantities if at all, were found to comprise 7-80% of the intracellular nucleotide pools in nine subjects with severe lead over-burden. Blood lead concentrations ranged from approximately equal to 200- to 400-microgram/dl packed cells, and the greatest accumulations of pyrimidine-containing nucleotides occurred in the two subjects with the highest blood lead levels. Most of the patients had mild or moderate anemia and moderate basophilic stippling evident in Wright's-stained peripheral smears. Pyrimidine nucleotidase activities were inhibited to 13-28% of the mean activity in normal control erythrocytes and even more so (5-15%) when compared to specimens with increased reticulocytes and young cells. Reticulocytosis was absent in two subjects and modest to moderate in the remainder, but erythrocyte assays revealed the substantial elevations in populations of young mean cell age. Inappropriately low reticulocyttial elevations in glucose-6-phosphate dehydrogenase expected in populations of young mean cell age. Inappropriately low reticulocyte responses may reflect hematopoietic suppressive effects of lead at a variety of metabolic loci.

Lead poisoning: association with hemolytic anemia, basophilic stippling, erythrocyte pyrimidine 5'-nucleotidase deficiency, and intraerythrocytic accumulation of pyrimidines.

Lead intoxication is accompanied by an acquired deficiency of erythrocyte pryimidine-specific, 5'-nucleotidase. Genetically determined deficiency of this enzyme is associated with chronic hemolysis, marked basophilic stippling of erythrocytes on stained blood films, and unique intraerythrocytic accumulations of pyrimidine-containing nucleotides. The present report documents that lead-induced deficiency when sufficiently severe gives rise to findings similar to the hereditary disorder. Whereas pyrimidine-containing nucleotides are virutally absent in the erythrocytes of normal and reticulocyte-rich blood, 12% of erythrocyte nucloetides in the blood of a patient with lead intoxication contained cytidine. Nucleotidase activity was about 25% that in normal erythrocytes and 15% or less of that expected in comparable reticulocyte-rich blood. The distribution of nucleotidase activity in patient erythrocytes is unknown, and much more severe deficiency could have been present in subsets of the cell populations analyzed. The findings indicate that the hemolytic anemia and increased basophilic stippling characteristic of certain cases of lead intoxication may share a common etiology with essentially identical features of the genetically determined disorder.

Hereditary hemolytic anemia with human erythrocyte pyrimidine 5'-nucleotidase deficiency.

A severe deficiency of a red cell pyrimidine 5'-nucleotidase was found to be associated with hereditary hemolytic anemia in four members of three kindreds. The syndrome was characterized by marked increases above normal in red cell basophilic stippling, total nucleotides, and GSH and by a fairly severe deficiency of ribosephosphate pyrophosphokinase (EC 2.7.6.1.). Patient erythrocytes uniquely contained large amounts of pyrimidine 5'-ribonucleotides. In earlier studies, these were erroneously considered to be adenosine phosphates, since all previous investigations of the nucleotides of human red cells and reticulocytes have shown 97% or more to contain adenine. Total nucleotides in patient cells were present in amounts 3-6 times greater than normal, and approximately 80% contained pyrimidine. The ultraviolet spectral curves of deproteinized red cell extracts exhibited a shift in maximum absorbance from the usual 256-257 nm to approximately 266-270 nm, and absorbance at 250, 270, 280, and 290 nm, expressed as a ratio of that at 260 nm, differed greatly from normal. The spectral characteristics of extracts provide the basis of a readily performed screening procedure, which does not require enzyme assay. The nucleotidase activity in deficient red cells assayed less than 14%, and usually less than 10%, of normal and much less in terms of reticulocyte-rich blood, where it was consistently found to be increased. The enzyme has a pH optimum of 7.5-8.0, is inhibited by EDTA, and does not utilize purine 5'-ribonucleotides or beta-glycerophosphate as substrates. While comparatively few family members have been available thus far for study, initial data are compatible with an autosomal, recessive mode of transmission of the deficiency. The pyrimidine 5'-ribonucleotides are presumably derived from RNA degradation and, not being diffusible, accumulate when the enzyme catalyzing their dephosphorylation is deficient. It is postulated that the prominent basophilic stippling results from retarded ribosomal RNA degradation secondary to accumulation of degradation products, namely pyrimidine 5'-ribonucleotides. Ribosephosphate pyrophosphokinase deficiency is considered to be an epiphenomenon. The mechanism responsible for increased red cell GSH is unknown.

An inherited molecular lesion of erythrocyte pyruvate kinase. Identification of a kinetically aberrant isozyme associated with premature hemolysis.

Atypical cases of heritable hemolytic anemia have been noted that conform clinically and biochemically to anemias of the pyruvatekinase (PK)-deficient type, except for the presence of apparently adequate quantities of erythrocyte-PK activity by the usual assay procedure. Investigations of four such anomalous cases, occurring in two unrelated families, are presented. Erythrocytes contained a kinetically aberrant isozyme of pyruvate kinase (PK(2)). Michaelis constants for the pathologic isozyme relative to phosphoenolpyruvate were over 10-fold greater than control values, but no kinetic abnormality was evident for the second substrate, adenosine diphosphate. PK(2) exhibited a pH optimum almost 1 U lower than the wild enzyme form (PK(1)). Significant differences were also evident in the functional stabilities of the isozymes. Leukocytes were unaffected. Family studies revealed paternal heterozygosity for quantitative PK deficiency of the usual type. Clinically normal maternal relatives and some siblings demonstrated intermediate deviations in erythrocyte-PK kinetics and reaction characteristics compatible with coexistence of normal PK(1) and kinetically abnormal PK(2). Hemolytic anemia in the propositi appeared to require simultaneous inheritance of the gene governing PK(2) production and its presumed allele resulting in quantitative PK deficiency. Both genetic defects were traced through three generations, the defective gene in both instances apparently resident on autosomes.A revision of the PK assay technique is suggested, since catalytic inefficiency of PK(2) was manifested only at low substrate concentrations and was therefore undetectable at the relatively high phosphoenolpyruvate levels employed in the conventional assay.

Substrate specificity and pH sensitivity of deoxyribonucleotidase and pyrimidine nucleotidase activities in human hemolysates.

Residual 5'-nucleotidase activities in hemolysates from nine subjects with severe hereditary deficiency of pyrimidine nucleotidase (PyrNase) were compared to those in normal and reticulocyte-rich controls. Dephosphorylation rates of 12 potential ribo- and deoxyribomononucleotide substrates were measured as a function of pH. Data confirmed the existence of at least two isozymes of 5'-nucleotidase, PyrNase, and 2'-deoxy-5'-ribonucleotide phosphohydrolase (dNase) distinguishable by differences in maximal velocities, substrate preferences and restrictions, and pH optima. PyrNase was confirmed to be active principally with pyrimidine substrates (UMP = dCMP greater than CMP much greater than dTMP greater than dUMP) at a pH optimum of 7.5 +/- 0.1. dNase activity occurred with both purine and pyrimidine substrates and was maximal with deoxy analogs (dIMP much greater than dUMP greater than dGMP greater than dTMP = dAMP much greater than dCMP) at a pH optimum of 6.2, but slight cross-reactivity occurred with some nondeoxy substrates (IMP greater than GMP greater than UMP = XMP greater than CMP). PyrNase and dNase may be complementary systems that serve physiologically to clear the cytosol of RNA and DNA degradation products during maturation of erythroid elements by conversion of nucleotide monophosphates to diffusible nucleosides.

Endogenous natural killer enhancing factor-B increases cellular resistance to oxidative stresses.

Natural killer-enhancing factor (NKEF) was identified and cloned on the basis of its ability to increase NK cytotoxicity. Two genes, NKEF-A and -B, encode NKEF proteins and sequence analysis presented suggests that each belongs to a highly conserved family of antioxidants. To examine the antioxidant potential of NKEF, we transfected the coding region of NKEF-B cDNA into the human endothelial cell line ECV304. The stable transfectant, B/1, was found to overexpress NKEF-B gene transcript and protein. We subjected B/1 to oxidative stress by either culturing them with glucose oxidase (GO), which continuously generates hydrogen peroxide, or by direct addition of hydrogen peroxide. We found that B/1 cells were more resistant than control cell lines. Resistance to hydrogen peroxide was originally thought to be mediated mainly by catalase and the glutathione cycle. Therefore, we used inhibitors to block the two pathways and found that B/1 cells were more resistant to oxidative stress than control cells when we used inhibitors to preblock either pathway. We also examined the cellular inflammatory responses to oxidized low-density lipoprotein (LDL) and bacterial lipopolysaccharide (LPS) by measuring monocyte adhesion to endothelial cells in vitro and found that B/1 cells were resistant to such responses. Lastly, we found that B/1 cells were more resistant to a novel chemotherapeutic agent CT-2584, which appears to kill tumor cells by stimulating production of reactive oxygen intermediates in mitochondria. These results demonstrate that the NKEF-B is an antioxidant that protects cells from oxidative stress, chemotherapy agents, and inflammation-induced monocyte adhesion. Furthermore, its expression may mediate cellular responses to proinflammatory molecules.

An isozyme of erythrocyte pyruvate kinase (PK-Los Angeles) with impaired kinetics corrected by fructose-1, 6-diphosphate.

A mutant isozyme of erythrocyte pyruvate kinase was found in a family of French-Canadian ancestry in association with hemolytic anemia. The isozyme was characterized by normal maximal activity, pH optimum, heat stability, and fructosediphosphate activation constants, but had markedly reduced affinity for the substrate, phosphoenolpyruvate. This kinetic defect was corrected almost entirely in vitro by low concentrations of fructosediphosphate.

Differential effects of low-level lead exposure on the natural isozymes of erythrocyte 5'-nucleotidase.

OBJECTIVE: Erythrocyte pyrimidine 5'-nucleotidase (Pyr-5'-N) is highly sensitive to heavy metal inactivation in vitro and in vivo, and a number of studies have verified its usefulness as a biomarker of acute and chronic lead exposures. Retrospective and prospective studies attempted to determine whether the known linearity of Pyr-5'-N inhibition by lead concentrations above 40 microg/dL whole blood might continue into the lowest range of exposures now considered to be toxic in children (<10-20 microg/dL), thereby extending its value as a biomarker of lead exposure. DESIGN: Activities of Pyr-5'-N and a lead-insensitive isozyme, deoxyribonucleotidase (d-5'-N), were compared to blood lead and free erythrocyte protoporphyrin (FEP) concentrations. RESULTS: Pyr-5'-N activities in erythrocytes from 70 children displayed an inverse linear correlation with whole blood lead of 1-35 microg/dL, whereas d-5'-N did not correlate. There was no apparent minimum threshold for Pyr-5'-N inhibition by lead. CONCLUSIONS: Linearity of Pyr-5'-N inhibition by lead extends throughout the range of clinical concern in pediatric cases. Pyr-5'-N/d-5'-N activity ratios may provide an even more sensitive, internally controlled biomarker of low-level lead overburden, since both isozymes vary comparably in activity as a function of reticulocytosis and mean red cell age.

Biphasic reaction kinetics in an anomalous isozyme of erythrocyte pyruvate kinase.

A mutant erythrocyte isozyme of pyruvate kinase (PK) (ATP: pyruvate phosphotransferase, EC 2.7.1.40) has been found in associatin with chronic hemolytic anemia in two siblings who were doubly heterozygous for the isozyme and for quantitative PK deficiency of the usual form. The isozyme was characterized by approximately normal maximum reaction velocities but had markedly decreased affinity for the substrate, phosphoenolpyruvate (PEP), with 5-fold to 10-fold increases in half-saturation constants and decreased interaction between substrate binding sites. Two distinctly separable kinetic patterns for PEP were observed with multiple specimens. Concentrations of fructose 1,6-diphosphate (FDP) required for half-maximal activation were two orders of magnitude greater than controls, and optimal pH was lowered to 6.5. stability at 4 degrees C was markedly decreased, but the lost enzyme could be reactivated by fdp for periods even longer than normal controls.

Inverting papillomas of the nose and paranasal sinuses.

Inverting papilloma of the nose and paranasal sinuses can sometimes be very difficult to distinguish from other nasal tumors, and the confusion ranges from allergic nasal polyposis to carcinoma. They are also certainly characterized by multiple recurrence, particularly after limited operations. The experience with 34 cases seen at UCLA over the past two decades is analyzed and a philosophy of treatment is outlined. We favor wide local excision which generally necessitates a lateral rhinotomy and medial maxillectomy. The operative approach will be described in detail.

Accuracy of frozen section diagnosis of parotid lesions.

The accuracy of frozen section diagnosis was analyzed in a review of 132 parotid lesions. Of 107 benign lesions, 93% were correctly diagnosed on frozen section analysis, but of 25 malignant lesions, only 9 frozen sections were accurately interpreted. This study points out the difficulty encountered in using the frozen section technique when dealing with malignant parotid lesions and the importance of the surgeon's active participation in the analysis.

Radiometric assessment of hexose monophosphate shunt capacity in erythrocytes of rhinoceroses.

OBJECTIVES: To measure metabolic rates of the hexose monophosphate shunt (HMPS) in erythrocytes of rhinoceroses, and to test the hypothesis that low concentrations of endogenous ATP in erythrocytes impair HMPS capacity, thereby increasing susceptibility to oxidant-induced hemolysis. ANIMALS: 13 black and 3 white rhinoceroses, free-ranging in several regions of southern Africa, and 1 Sumatran rhinoceros in US captivity. PROCEDURE: HMPS fluxes were measured in rhinoceros erythrocytes with carbon-labeled glucose in the presence and absence of known HMPS activators. RESULTS: Compared with values for human erythrocytes, mean basal state HMPS fluxes were appreciably lower (22 to 46%) in all 3 rhinoceros species studied. Shunt activators increased HMPS rates approximately 5-fold over basal rates in rhinoceros erythrocytes, compared with increases in humans of 10-fold with ascorbate and 15-fold with methylene blue. Stimulated HMPS rates in human erythrocytes were quantitatively 5- to 10-times greater than those observed in rhinoceros erythrocytes. Overall HMPS catabolic rates were completely independent of intracellular ATP concentrations. CONCLUSIONS AND CLINICAL RELEVANCE: HMPS glycolytic and recycling rates and responses to activators are inherently low in erythrocytes from 3 species of rhinoceros, likely contributing to (but not solely responsible for) the high susceptibility of black rhinoceroses to oxidant-induced hemolysis. Slow erythrocyte HMPS capacities were independent of intracellular ATP concentrations, invalidating a current hypothesis regarding the pathogenesis of hemolytic anemia in captive black rhinoceroses. Limitations in HMPS capacities emphasize the importance of protecting rhinoceroses from exposure to drugs, chemicals, toxins, foodstuffs, and other conditions known to increase production of oxidizing metabolites, reactive oxygen species, and free radicals.

Role of excessive maternal iron in the pathogenesis of congenital leukoencephalomalacia in captive black rhinoceroses (Diceros bicornis).

OBJECTIVE: To investigate the possibility that excessive maternal iron (overload) may contribute to development of congenital leukoencephalomalacia in captive black rhinoceroses. SAMPLE POPULATION: Tissue specimens and serum samples from 18 rhinoceroses in 2 kindreds harboring 4 (possibly 5) affected female calves. PROCEDURE: Fresh and archival sera and necropsy tissue specimens were evaluated to determine the nature and extent of iron overload in captive and wild black rhinoceroses as well as other rhinoceros species. RESULTS: Quantitative serum and tissue assays of iron and iron analytes, corroborated by histopathologic findings, indicated that these kindreds carried the greatest body burdens of iron yet found among captive black rhinoceroses. Fourteen of 18 rhinoceroses had the highest serum ferritin concentrations measured among 64 black rhinoceroses in captivity in the United States. Dams of affected calves had serum ferritin concentrations 2 orders of magnitude higher than clinically normal humans, equids, or free-ranging rhinoceroses. A neonatal serum sample from 1 affected female calf had a high ferritin concentration (approx 100-fold increase), but a male sibling of another affected female did not, suggesting a possible sex disparity in fetal response to maternal iron overload. Morphologic hallmarks of hemochromatosis were prominent in dams and grandams of affected calves. CONCLUSIONS AND CLINICAL RELEVANCE: Excessive maternal iron may affect female fetuses more than males, possibly inducing leukoencephalomalacia by catalyzing production of highly toxic hydroxyl free radicals during crucial periods of in utero development. Reduction of maternal iron overload may decrease the probability of developing leukoencephalomalacia and some other disorders commonly affecting rhinoceroses in captivity.

Acute intravascular hemolysis in the black rhinoceros: erythrocyte enzymes and metabolic intermediates.

Enzymes of aerobic and anaerobic glycolysis, glutathione cycling, and nucleotide metabolism were assayed on erythrocytes from 7 healthy rhinoceroses, 2 rhinoceroses during periods of intravascular hemolysis, and 1 rhinoceros without clinical signs of illness, which was the mother of 3 offspring with intravascular hemolytic syndrome. Measurements also were made of erythrocyte concentrations of glycolytic intermediates, adenine nucleotides, and glutathione. Although comparison of results for healthy and affected rhinoceroses did not identify an enzyme abnormality as a cause for the hemolytic syndrome, the data provided information regarding the metabolic characteristics of erythrocytes from healthy rhinoceroses.

Familial nonspherocytic hemolytic anemia in poodles.

Nonspherocytic hemolytic anemia, characterized by marked reticulocytosis, hepatosplenomegaly, hemosiderosis of reticuloendothelial organs and bone marrow myelofibrosis, and osteosclerosis, was diagnosed in 5 related Poodles. The unremitting anemia was clinically evident by 1 year of age, and was fatal as early as 3 years of age. Despite intense diagnostic endeavors including RBC fragility studies, RBC enzyme assays, and hemoglobin electrophoresis, the cause of this nonspherocytic hemolytic anemia remains to be determined.

Idiopathic hemorrhagic vasculopathy syndrome in seven black rhinoceros.

Idiopathic hemorrhagic vasculopathy syndrome (IHVS) was diagnosed in 7 black rhinoceros; this newly described syndrome is characterized by severe body swelling in conjunction with a rapid and profound decrease in Hct. The disorder may be acute or chronic, may recur, and is potentially fatal. Five of the rhinoceros survived an initial episode of IHVS, and 2 of these 5 survived a recurrent episode of IHVS. Two rhinoceros died during treatment of IHVS. Treatment protocols varied, but all 7 rhinoceros received broad-spectrum antibiotics, because an infectious cause was suspected. All rhinoceros also received nonsteroidal antiinflammatory drugs and supportive care. Idiopathic hemorrhagic vasculopathy syndrome has many similarities to other vasculopathies of domestic animals, such as equine purpura hemorrhagica, but it also appears to have unique identifying features. It has been hypothesized that IHVS may be an immune response to an as yet unidentified infectious agent. Thorough and extensive testing has not identified the potential causative agent, nor the factors that predispose some black rhinoceros to developing IHVS. Further research into the rhinoceros immune system is ongoing and should help elucidate the mechanisms through which IHVS develops.

"Biospheric medicine" as viewed from the two-year first closure of Biosphere 2.

Biosphere 2 is a 3.15-acre, 7-million ft. enclosed ecological space near Tucson, AZ. It contains five wilderness and two domestic biomes (rain forest, savanna, desert, ocean, marsh; agricultural station, living quarters), an original introduction of 3,800 species (approximately 20% extinctions have occurred), and a large basement "technosphere." Sealed inside Biosphere 2 in September 1991, four women and four men, including two of the authors, maintained themselves and the various systems for 2 yr, the longest-sustained "isolated confined environment" period on record. MMPI psychological profile scores for Biosphere 2 crewmembers correlated closely with those reported for astronauts and shuttle applicants. Major medical problems encountered during the 2 yr included adaptation to a low-calorie (1800-2200 kcal.d-1 per person) but otherwise nutritionally adequate diet, with substantial weight loss (18% for men, 10% for women), and a declining oxygen atmosphere (down to 14.2%). Life in a miniworld such as Biosphere 2 may differ substantially from life in a space station or temporary planetary base. These differences include multiple, shifting, sometimes opposing post-launch objectives; complete self-sustenance with recycling of virtually all materials within a highly complex biologic system; retooling of some areas of practical medicine; an attention to "culture" as a social dynamic and how that may influence crew and leadership selection in a societal rather than a quasi-military community. Assuming that long-term planetary colonies must be largely self-sustaining (due to costs of supply over great distances), they must of necessity approach the condition of biospheres. Subject to chaos dynamic (nonlinear dynamic) perturbations, the behavior of complex biospheres will be inherently non-predictable--as opposed to the linear dynamic situation of most space missions--and will require of the inhabitants, including the medical team, a wide range of coping abilities. Under the circumstances, and while strong similarities exist, important differences may serve to distinguish "biospheric medicine" from "space medicine."

Acute lymphoblastic leukemia in a juvenile southern black rhinoceros (Diceros bicornis minor).

A 21-mo-old female southern black rhinoceros (Diceros bicornis minor) developed acute upper respiratory dyspnea in association with lymphadenopathy and marked immature lymphocytosis. A diagnosis of acute lymphoblastic leukemia was reached on the basis of the morphologic and cytochemical characteristics of peripheral lymphoblasts. Antineoplastic chemotherapy included administration of cytarabine, cyclophosphamide, vincristine, and doxorubicin, with clinical remission achieved 19 days after initiation of treatment. The rhinoceros died, however, of congestive heart failure, presumably secondary to doxorubicin cardiotoxicity and a particular sensitivity of rhinoceros myocardial tissue to free hydroxyl radicals. The pharmacologic effects of any therapeutic agent need to be carefully considered before use in the black rhinoceros, especially within the context of the unique physiology of this species.