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Biomedical subjects

J W Harvey

Publications and source records attributed to J W Harvey.

At least 19 recordsLinked to original sources
PubMed2003

Methemoglobinemia and eccentrocytosis in equine erythrocyte flavin adenine dinucleotide deficiency.

This report describes erythrocyte biochemical findings in an adult Spanish mustang mare that exhibited persistent methemoglobinemia, eccentrocytosis, and pyknocytosis that were not related to the consumption or administration of an exogenous oxidant. The methemoglobinemia was attributed to a deficiency in cytochrome-b5 reductase (Cb5R) activity, and the eccentrocytes and pyknocytes were attributed to a marked deficiency in reduced nicotinamide adenine dinucleotide phosphate-dependent glutathione reductase (GR) activity that resulted in decreased reduced glutathione concentration within erythrocytes. The GR activity increased to a near-normal value after addition of flavin adenine dinucleotide (FAD) to the enzyme assay, indicating a deficiency of FAD in erythrocytes. The methemoglobinemia, eccentrocytosis, and pyknocytosis were attributed to deficiency of FAD in erythrocytes because the GR and Cb5R enzymes use FAD as a cofactor. This deficiency in FAD results from a defect in erythrocyte riboflavin metabolism, which has not been documented previously in animals.

Animals↗
PubMed1999

Western immunoblot analysis of the antigens of Haemobartonella felis with sera from experimentally infected cats.

Cats were experimentally infected with a Florida isolate of Haemobartonella felis in order to collect organisms and evaluate the immune response to H. felis. Cryopreserved organisms were thawed and injected intravenously into nonsplenectomized and splenectomized cats. Splenectomized animals were given 10 mg of methylprednisolone per ml at the time of inoculation. Blood films were evaluated daily for 1 week prior to infection and for up to 60 days postinfection (p. i.). Blood for H. felis purification was repeatedly collected from splenectomized animals at periods of peak parasitemias. Organisms were purified from infected blood by differential centrifugation, separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and transferred to nitrocellulose membranes for immunoblot analysis. Serum was collected from nonsplenectomized animals prior to and for up to 60 days p.i. and was used on immunoblots to identify antigens. The combination of splenectomy and corticosteroid treatment resulted in marked, cyclic parasitemias without concurrent severe anemia, providing an opportunity to harvest organisms in a manner that was not lethal to the animals. Several antigens (150, 52, 47, 45, and 14 kDa) were identified. An antigen with a molecular mass of approximately 14 kDa appeared to be one of the most immunodominant and was consistently recognized by immune sera collected at various times during the course of infection. These data suggest that one or more of these antigens might be useful for the serologic diagnosis of H. felis infections in cats.

Anaplasmataceae↗
PubMed1999

Hematologic effects of cytauxzoonosis in Florida panthers and Texas cougars in Florida.

Cytauxzoon felis is a long-recognized hemoparasite of free-ranging Florida panthers (Puma concolor coryi), but its prevalence and effect on the population has not been assessed. Red blood cell indices and white blood cell counts were compared between infected and noninfected Florida panthers and Texas cougars (Puma concolor stanleyana) from 1983-1997 in Florida (USA). The prevalence of cytauxzoonosis for both populations was 39% (11/28) for Texas cougars, 35% for Florida panthers (22/63) and 36% overall. Thirteen hematologic parameters were compared between C. felis positive and negative panthers and cougars. Florida panthers had significantly lower mean cell hemoglobin count (MCHC) and higher white blood cell (WBC), neutrophil, monocyte and eosinophil counts (P < or = 0.05) than Texas cougars. Infected Florida panthers had significantly lower mean cell hemoglobin (MCH) and monocyte counts and higher neutrophil and eosinophil counts than infected Texas cougars. Although statistically significant differences were measured for hematologic parameters in C. felis positive panthers and cougars, biologically significant differences were not likely because values were generally within expected reference ranges for healthy animals. Cytauxzoonosis does not appear to have a negative effect on the hematologic parameters of chronically infected panthers and cougars. Potential transient changes during initial infection were not evaluated.

Analysis of Variance↗
PubMed1996

Congenital erythrocyte enzyme deficiencies.

Congenital hemolytic anemias resulting from PK, PFK, and G6PD enzyme deficiencies have been reported in domestic animals. Dogs with PFK deficiency may have episodes of intravascular hemolysis with hemoglobinuria in addition to a persistent compensated hemolytic anemia. Patients with mild G6PD deficiency are not anemic but may show increased susceptibility to oxidant-induced erythrocyte injury. Persistent methemoglobinemia has been reported in dogs and cats with methemoglobin reductase enzyme deficiency. Affected animals have cyanotic-appearing mucous membranes but show no or only mild clinical signs attributable to hypoxemia. Enzyme assays are usually done after acquired causes of hemolytic anemia and methemoglobinemia have been ruled out.

Animals↗
PubMed1996

Fatal cytauxzoonosis in a captive-reared white tiger (Panthera tigris).

Fatal (Panthera tigris) cytauxzoonosis was diagnosed in a 7-year-old female white tiger. The tiger presented with a 2-day history of anorexia and lethargy. She was mildly dehydrated, with a temperature of 105.2 F and a hematocrit of 26%. Over the next day, icterus developed, and her physical condition progressed to recumbency, coma, and death. Hematologic findings obtained shortly before death included icteric plasma, severe thrombocytopenia, mild anemia, hematuria, and parasites consistent with Cytauxzoon felis in circulating erythrocytes. Gross necropsy findings included generalized icterus, generalized petechiae and ecchymoses, splenomegaly, and peribronchial edema. Histologic changes included large numbers of intravascular macrophages containing developmental stages of Cytauxzoon felis that partially or completely occluded blood vessels in the lung, spleen, liver, and bone marrow. Except for an experimental infection of a bobcat, fatal cytauxzoonosis has not previously been diagnosed in felids other than domestic cats. These findings raise questions regarding the pathogenicity of this organism in felids and may impact husbandry and interstate transfer of captive large cats.

Anemia↗
PubMed1994

Methemoglobin reductase deficiency in a cat.

During ovariohysterectomy of a 6-month-old domestic shorthair cat, extravasated blood appeared brown. Methemoglobinemia was considered likely on the basis of discoloration of oxygenated blood. The absence of clinical signs of toxicosis, inability to identify a source of oxidant that could cause methemoglobinemia, and persistence of cyanotic-appearing tongue and mucous membranes in this cat made a drug-induced cause unlikely, and was suggestive of a congenital disorder. Subsequent analysis revealed 49.6% methemoglobin (normal, 0 to 1.1%), resulting from erythrocyte methemoglobin reductase deficiency (21% of normal activity).

Animals↗
PubMed1994

Metabolic and work capacity of skeletal muscle of PFK-deficient dogs studied in situ.

Mechanical and metabolic relationships of muscle lacking phosphofructokinase (PFKD) activity were compared with muscle having normal phosphofructokinase (NORM) activity by using the gastrocnemius-plantaris muscle group with isolated circulation in situ. Muscle contractile properties were similar in both groups. Initial power output (W) during repetitive tetanic (200 ms, 50 impulses/s) isotonic contractions was similar in both groups; however, W declined significantly more (30-80%) in PFKD than in NORM muscle over time, with a constant O2 uptake (VO2)/W. Despite similar O2 and substrate delivery, PFKD muscle had a lower VO2 (42-55%), less glucose uptake, similar free fatty acid uptake, and lactic acid uptake rather than output, during contractions. Muscle venous H+ concentration, strong ion difference, and PCO2 increased during contractions, the magnitude of change being smaller in PFKD muscle. Elevating arterial lactate concentration before contractions in PFKD muscle resulted in significant improvements in W and VO2 without altering the acid-base exchange at the muscle. Increasing O2 delivery by increasing arterial O2 concentration in PFKD dogs did not improve W or VO2. We conclude that, despite no inherent mechanical or contractile differences, PFKD muscle has a severely limited oxidative capacity and exaggerated fatigue and blood flow responses to contractions due to limited substrate metabolism resulting from the inability to utilize glycogen and/or glucose.

Acid-Base Equilibrium↗
PubMed1994

Equine glucose-6-phosphate dehydrogenase deficiency.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a well-characterized X-linked inherited disorder in humans but has not been reported in horses. We describe a persistent hemolytic anemia and hyperbilirubinemia due to a severe G6PD deficiency in an American Saddlebred colt. Other abnormalities in the colt's erythrocytes as compared with those of healthy horses (n = 22-35) included increased activities of hexokinase and pyruvate kinase, decreased concentrations of reduced glutathione and reduced nicotinamide adenine dinucleotide phosphate (NADP), and increased concentration of oxidized NADP. Morphologic abnormalities included eccentrocytosis, pyknocytosis, anisocytosis, macrocytosis, and increased number of Howell-Jolly bodies. Scanning and transmission electron microscopic examinations revealed that eccentrocytes had contracted to spherical regions and thin collapsed regions. Eccentrocytes were more electron dense than were normal erythrocytes when examined by transmission electron microscopy. When exposed to acetylphenylhydrazine, erythrocytes from the G6PD-deficient colt produced more and smaller Heinz bodies than did erythrocytes from normal horses. Abnormalities in the colt's dam included presence of eccentrocytes and pyknocytes; her average erythrocyte G6PD activity was slightly below the range of reference values.

Anemia, Hemolytic↗
PubMed1992

Seroprevalence of babesiosis in Greyhounds in Florida.

An indirect fluorescent antibody test was used to serologically survey Greyhounds from 10 kennels that are part of the racing Greyhound industry in Florida. Age of dogs ranged from 11 months to 11 years. Additionally, 50 adult non-Greyhound pet dogs were consecutively surveyed. Of 393 Greyhounds tested, 181 (46%) were seropositive for babesiosis; pet dogs were seronegative. Slightly higher percentage of seropositive males than females was observed, but this difference was only significant (P less than 0.01) in the 2- to 5-year age class. Male dogs less than 2 years old had significantly (P less than 0.01) lower seroprevalence than did male dogs greater than 2 years old. All 46 Greyhounds that were actively racing at the time of sample collection were seronegative. Dogs were classified into 2 groups on the basis of whether the kennel owner had sought veterinary attention for anemic pups. The 5 kennel owners that had sought veterinary attention (group A) had significantly (P less than 0.01) higher seroprevalence (78.5%), compared with the 5 that had not sought veterinary attention (group B; 23.0%). Seroprevalence of babesiosis in Greyhounds in Florida was comparable to that reported in a limited survey of other southeastern states. It appears to be higher than that in the pet population. Breeding kennels in Florida and other southeastern states from which anemic pups originate should be screened for babesiosis.

Age Factors↗
PubMed1992

Characterization of phosphofructokinase-deficient canine erythrocytes.

Dogs homozygously affected with muscle-type phosphofructokinase (PFK) deficiency had about 20% of normal erythrocyte PFK activity and exhibited a compensated haemolytic anaemia. Erythrocyte glucose-6-phosphate and fructose-6-phosphate concentrations were increased and dihydroxyacetone phosphate and 2,3-bisphosphoglycerate values were below normal in affected dogs. Other intermediates distal to the PFK step were not significantly below normal and fructose-1,6-bisphosphate was even above normal. Erythrocyte ATP was higher than normal in affected dogs owing to the reticulocytes present. Abnormal adenylate metabolism was demonstrated by low ATP/AMP and ADP/AMP ratios and the inability to maintain ATP content when affected erythrocytes were incubated with cyanide. Glucose-1,6-bisphosphate content was normal, and fructose-2,6-bisphosphate content in affected canine erythrocytes was higher than normal. Studies of erythrocyte PFK isozymes revealed altered enzyme kinetic properties in affected dogs which appeared to be due to the loss of the M-type subunit.

Adenine Nucleotides↗
PubMed1992

Developmental changes of 6-phosphofructo-1-kinase subunit levels in erythrocytes from normal dogs and dogs affected by glycogen storage disease type VII.

1. The subunit proportions (L:M:C) of the PFK isozymes from normal adult erythrocytes were 2:86:12. Affected adult erythrocyte 6-phosphofructo-1-kinase (PFK) isozymes contained normal L-type (31%) and C-type (61%) subunits as well as a small amount (8%) of truncated M-type subunit. 2. When measured within 24 hr of birth, both normal and affected dog erythrocytes contained high PFK activities due to elevated levels of the L-type subunit. As the dogs matured, PFK activity decreased due to a greater than 99% loss of the L-type subunit. 3. By 2 weeks of age, the M-type and C-type subunits in normal dog PFK isozymes increased several-fold and attained near adult levels. 4. During post-natal development, the L-type subunit from affected dog erythrocytes decreased more rapidly than from normal dog erythrocytes; but it was maintained at a higher level in the affected adult erythrocytes. Also, in the affected dog erythrocytes, truncated M-type subunits were detected; and the initially high levels of the C-type subunit decreased approximately 50% after 4 weeks.

Aging↗
PubMed1992

Specialized hematology tests.

In conclusion, many specialized tests for the evaluation of anemia and RBC abnormalities can readily be performed in-house or by commercial laboratories. Tests include RBC indices, examination of blood smears (for morphological changes, infectious agents, basophilic stippling, and polychromasia), reticulocyte counts, iron stains, serum iron determinations, Heinz body counts, and methemoglobin tests. These diagnostic tests should routinely be used for the evaluation of hematologic abnormalities that are detected by a CBC. Accurate interpretation of test results will provide vital information on the pathophysiological and/or etiologic mechanisms of disease and point the way to successful therapeutic intervention. Failure to adequately resolve some hematologic abnormalities, particularly in breeds in which heritable disease is a consideration, may require additional tests, including serum haptoglobin, ferritin and erythropoietin measurement, or assays for RBC enzymes, such as methemoglobin reductase, PK, and PFK. These tests usually are available only through research laboratories or hematology specialists, and it is advisable to consult with a veterinary clinical pathologist for referral to the appropriate individual or laboratory.

Anemia↗
PubMed1990

Polysaccharide storage myopathy in canine phosphofructokinase deficiency (type VII glycogen storage disease).

A severe, progressive myopathy developed in an 11-year-old, phosphofructokinase (PFK)-deficient, male, English Springer Spaniel dog. Results from a routine neurological examination were normal. Examination of histologic sections of skeletal muscle revealed large accumulations of material in some myofibers. These deposits were pale, basophilic, somewhat flocculent, and slightly granular with hematoxylin and eosin stain. Most fascicles examined in sections of limb and trunk muscles were affected to some degree, with up to 10% of muscle fibers being involved. Deposits stained strongly with periodic acid-Schiff and were resistant to digestion by alpha amylase but were removed by incubation with gamma amylase. Deposits were faintly positive with Gomori's methenamine silver technique and alcian blue (pH 2.5) and were brown-gray with Lugol's iodine solution but were negative with other stains. Based on staining characteristics, the deposits seemed to consist primarily of an amylopectin-like polysaccharide(s). Alcian blue staining (pH 2.5) was removed by treatment with neuraminidase but not with hyaluronidase, indicating that some sialic acid residues were also present. Electron microscopically, the deposits were composed of short granular filaments, small granules and amorphous material. They were not membrane bound. The morphologic appearance and staining characteristics of the deposits were remarkably similar to deposits previously described in human PFK-deficient myopathy. As expected, total PFK activities were markedly reduced when assayed in skeletal muscles of this dog. In contrast with other PFK-deficient dogs, muscle glycogen in this animal was not increased above that of normal dogs.

Animals↗
PubMed1989

Postnatal hematologic development in phosphofructokinase-deficient dogs.

Adult dogs with phosphofructokinase (PFK) deficiency have compensated hemolytic anemia, due to an absolute or functional deficiency of the muscle-type (M-type) subunit that normally accounts for a majority of total erythrocyte PFK activity in dogs. Potential effects of PFK deficiency on hematologic development were evaluated in dogs. Routine hematologic parameters were similar in normal and affected dogs when 1 day old, because all newborn dogs had erythrocyte PFK activities about three times that of normal adult dogs. Based on chromatographic separation of PFK isozymes and enzyme immunoprecipitation studies, the high PFK activity at birth was attributed to the predominance of the liver-type (L-type) subunit of PFK, which is negligible or absent in normal adult dog erythrocytes. Both total PFK activities and the amounts of L-type subunit present decreased dramatically during the first 6 to 8 weeks of life. The muscle-type subunit was negligible or absent at birth, but appeared and increased as the L-type decreased in normal dogs. These changes may result from the replacement of erythrocytes formed in the fetus with those formed after birth. A postnatal physiologic anemia developed to a similar degree in both affected and normal dogs because of decreases in both mean corpuscular volume and erythrocyte numbers. Reticulocyte counts were high in all dogs at birth and remained high in affected dogs, but decreased from 2 months of age onward in normal dogs. Erythrocyte 2,3-diphosphoglycerate (DPG) values were very low in all newborn pups and increased to values expected for adults in the respective groups by 2 to 4 weeks of age. A low 2,3-DPG concentration occurs in affected dogs because PFK deficiency inhibits glycolysis above the side shunt that forms 2,3-DPG.

Adenosine Triphosphate↗
PubMed1989

A comparison of dummy variable versus traditional multiple discriminant function analysis.

The authors compare the use of dummy variable and traditional multiple discriminant function analysis when dealing with research questions where ratio or nominal scale independent variables can be used. A healthcare-related example of using dv MDF is given and the authors conclude that it is superior to traditional MDF for determining variable importance and developing market segment profiles.

Analysis of Variance↗
PubMed1988

Babesiosis in a litter of pups.

Babesia canis infection was diagnosed in a litter of seven 3-week-old Mastiff pups kept in a north Florida kennel. The pups were evaluated because of poor weight gain; the smallest pup also was markedly lethargic. Six of the pups were anemic and thrombocytopenic. A positive linear correlation between PCV and absolute reticulocyte count suggested that the variation in PCV may have been related more to the ability of a pup to increase erythrocyte production than to a difference in magnitude of erythrocyte destruction. All pups recovered from clinical signs and hematologic abnormalities attributable to babesiosis within 2.5 weeks after treatment with diminazene aceturate. Transient neurologic signs observed in 1 pup 3 days after treatment were believed to represent an adverse drug reaction. The dam of the litter had a serum titer of 1:640 for B canis, but appeared healthy, as did approximately 30 other adult dog in the kennel. The strain of B canis infecting dogs in the kennel caused severe illness and death in some pups, but clinically inapparent disease in adult dogs.

Animals↗
PubMed1988

Effect of 2,3-diphosphoglycerate concentration on the alkaline fragility of phosphofructokinase-deficient canine erythrocytes.

1. Erythrocytes in whole blood samples from dogs with phosphofructokinase (PFK) deficiency had lower 2,3-diphosphoglycerate (2,3-DPG) concentrations, higher ATP concentrations, and were more alkaline fragile than normal canine erythrocytes. 2. Reticulocytes from a PFK-deficient dog contained nearly three times the ATP concentration of normal canine erythrocytes, and had 2,3-DPG concentrations similar to normal canine erythrocytes. 3. PFK-deficient reticulocytes are not alkaline fragile. 4. The erythrocyte 2,3-DPG concentration in whole blood samples from PFK-deficient dogs was increased to normal by in vitro incubation with dihydroxyacetone, pyruvate and phosphate. This incubation resulted in only a slight increase in ATP concentration. 5. The alkaline fragility of these 2,3-DPG replenished PFK-deficient erythrocytes was normal. 6. Findings in this study indicate that the increased alkaline fragility of canine PFK-deficient erythrocytes is the result of decreased intracellular 2,3-DPG concentration.

2,3-Diphosphoglycerate↗