A multicenter prospective evaluation of owner medication adherence for feline cardiovascular disease in the referral setting.

OBJECTIVE: The aim of this paper is to evaluate owners' chronic medication adherence for management of feline cardiovascular disease in the small animal referral setting. ANIMALS, MATERIALS AND METHODS: A questionnaire-based study of owners at five multispecialty, small animal referral centers was conducted. Owners completed a written survey evaluating demographics, degree of medication adherence, and difficulties encountered for medication adherence. Owners were free to decline participation in the study. RESULTS: Fifty-four questionnaires were available for review. The most common diagnosis was hypertrophic cardiomyopathy (n = 31, 57.4%). Clopidogrel was the most cited medication that was difficult to administer consistently (n = 13, 24.0%) although twenty owners (37.0%) reported no difficulty consistently administering medications. "Taste of medication" (n = 14, 25.9%) was the most reported reason for difficulty medicating their cat, and most owners (n = 36, 66.7%) stated twice daily was the highest frequency of heart medications they feel they can consistently administer. Fifty owners (92.6%) met the criteria for medication adherence. CONCLUSIONS: Chronic medication adherence in this study population was high. Clopidogrel was the most difficult medication to consistently administer, and twice a day dosing was the highest frequency of medication administration most owners could achieve. Cardiologists should be aware of these factors when determining optimal treatment protocols for the management of cardiovascular disease in cats.

The beta and gamma classes of carbonic anhydrase.

There are currently five (alpha, beta, gamma, delta, zeta) classes of carbonic anhydrases (CA's) of which the alpha-class from mammalian sources has been studied to a much greater extent compared to the other four classes. Yet, CA's other than the alpha-class are widely distributed in Nature and play important roles in human health, the global carbon cycle, and industrial applications. In aerobic prokaryotes, beta-class CA's are implicated in maintaining internal pH and CO(2)/bicarbonate balances required for biosynthetic reactions. In anaerobic prokaryotes, beta-class CA's are implicated in the transport of CO(2) and bicarbonate across the cytoplasmic membrane that regulates pH and facilitates acquisition of substrates and product removal required for growth. In phototrophic organisms, beta-class CA's are particularly important for transport and concentration of CO(2) and bicarbonate for photosynthesis. The delta- and zeta-classes are proposed to function in marine diatoms to concentrate CO(2) for photosynthesis. Physiological roles for the gamma-class are not as well documented; however, the active site architecture and catalytic mechanism is well understood as are patterns of inhibition by sulfonamides and anions.

Severe factor V deficiency presenting with intracranial haemorrhage during gestation.

We present a case of intracranial haemorrhage detected by ultrasound at 36 weeks gestation in a foetus who was ultimately diagnosed with severe factor V deficiency. An abnormality of the foetal heart rate, auscultated at a routine antenatal visit, prompted an investigation that led to an ultrasound examination and detection of an intracranial haemorrhage and low amniotic fluid volume. An intrauterine foetal demise was averted. The clinical scenario in this case raises the issue of how often a stillbirth with intracranial haemorrhage may result from unrecognized factor deficiency.

Genitourinary complications of sickle cell disease.

PURPOSE: In the last half century the molecular biology, pathophysiology and natural history of sickle cell disease have been well defined. Sickle cell disease causes microvascular occlusion, which is manifested in most organ systems. The genitourinary tract is most commonly affected by hematuria, urinary tract infection and priapism but other more serious sequelae have been identified. MATERIALS AND METHODS: We performed a computerized MEDLINE search from 1965 to the present and a bibliographic review of cross references. These references were analyzed for meaningful findings and case reports. RESULTS: The diagnosis and management of sickle cell disease have advanced rapidly with a significant increase in the life expectancy of affected patients and recognition of a greater number of genitourinary complications. Renal function may be mildly altered or lost completely. Patients with sickle cell disease are at increased risk for urinary tract infection. Priapism is a painful complication of sickle cell disease that is poorly understood and challenging to treat and prevent. Testicular infarction has also been noted. Furthermore, renal medullary carcinoma, a highly lethal tumor, develops almost exclusively in young patients with sickle cell trait. CONCLUSIONS: Heightened awareness of the genitourinary complications of sickle cell disease may prevent end stage disease, including renal failure and impotence. New forms of therapy for sickle cell disease, such as hydroxyurea, may prevent these complications in the future.

Hydroxyurea therapy for pediatric patients with hemoglobin SC disease.

PURPOSE: Hydroxyurea (HU) has laboratory and clinical efficacy in hemoglobin SS (HbSS) disease, but its benefits in hemoglobin SC (HbSC) disease are unknown. A recent adult HbSC disease pilot trial with HU therapy documented a modest laboratory benefit. Our goal was to evaluate the laboratory and clinical responses of selected pediatric patients with severe HbSC disease to HU therapy. PATIENTS AND METHODS: As part of a retrospective case series, patients were selected from the Duke Pediatric Sickle Cell Program based on the frequency and severity of their vasoocclusive events or an episode of acute chest syndrome. Oral HU therapy was started as a single daily dose and increased to the maximally tolerated dose based on myelosuppression. Laboratory evaluation was performed at baseline and monthly thereafter. Once the maximum tolerated dose was reached, laboratory data were monitored bimonthly. RESULTS: We treated six severely affected pediatric HbSC patients with HU for a median of 27 months. Mean corpuscular volume increased significantly (+26 fL) without change in hemoglobin concentration (-0.1 g/dL); neutrophils decreased significantly. Percentage of fetal hemoglobin (+8.5%) and percentage of F cells (+35.7%) increased significantly. Two experienced only mild and reversible toxicity. CONCLUSION: The laboratory responses in our pediatric patients with HbSC disease were striking, with increases in percentage of fetal hemoglobin and percentage of F-cells approaching responses observed in adult and pediatric patients with HbSS disease. All patients improved clinically. Our findings demonstrate that HU therapy benefits pediatric patients with severe HbSC disease, although larger clinical trials of HU therapy in HbSC disease are warranted.

Effects of inherited thrombophilic mutations in an adolescent with antiphospholipid syndrome and systemic lupus erythematosus.

Thrombophilia can result from either inherited or acquired conditions. We describe a teenager who developed extensive thrombosis requiring aggressive and prolonged anticoagulation. Laboratory evaluation revealed an acquired lupus anticoagulant, consistent with the antiphospholipid antibody syndrome (APS). DNA analysis revealed inherited thrombophilic mutations in the factor V and methylene tetrahydrofolate reductase genes. We believe that the combination of inherited and acquired hypercoagulable conditions affected her therapeutic response to anticoagulant therapy. Inherited thrombophilic DNA mutations may contribute to the hypercoagulability observed in patients with acquired thrombophilic conditions such as APS and systemic lupus erythematosus.

An infant with homozygous hemoglobin D-Iran.

Hemoglobin D-Iran (Hb D-Iran, beta 22 Glu-->Gln) is a beta-chain variant that was first described in 1973. Hb D-Iran in combination with normal Hb A (Hb D-Iran trait) is a benign condition. Hb D-Iran has also been described in combination with sickle hemoglobin and beta thalassemia, but never as a homozygous mutation. The authors describe a case of homozygous Hb D-Iran in an infant of Pakistani descent. The hematologic values, hemoglobin electrophoresis, peripheral blood smear, and clinical course to date suggest that homozygous Hb D-Iran is a relatively benign condition with mild microcytic anemia, poikilocytosis, and minimal hemolysis.

Influence of bilirubin uridine diphosphate-glucuronosyltransferase 1A promoter polymorphisms on serum bilirubin levels and cholelithiasis in children with sickle cell anemia.

PURPOSE: Genetic mutations in the uridine diphosphate (UDP)-glucuronosyltransferase 1A (UGT1A) enzyme promoter have been associated with unconjugated hyperbilirubinemia and Gilbert syndrome. The effects of UGT1A promoter polymorphisms on serum bilirubin levels and symptomatic gallstone formation were studied in a cohort of children with sickle cell anemia (SCA). METHODS: The UGT1A promoter genotype was deterrmined for 115 consecutive children with SCA. Steady-state laboratory parameters and previous cholecystectomy for symptomatic gallstones were recorded retrospectively, then analyzed according to UGT1A genotype. RESULTS: Children with SCA had a lower frequency of the normal (TA)6 UGT1A promoter allele (0.413) than the abnormal (TA)7 allele (0.461). A previously described shorter (TA)5 allele (frequency 0.074) and longer (TA)8 allele (frequency 0.052) were also observed. Children with the 7/7 UGT1A genotype had a significantly higher mean bilirubin level (5.8 +/- 3.1 mg/dL) than those with the 6/6 (2.4 +/- 0.8 mg/dL) or 6/7 genotype (3.0 +/- 1.1 mg/dL; P < 0.001 by analysis of variance). Patients with the 7/7 genotype were more likely to have previous cholecystectomy (87.5%) than those with the 6/6 (35.7%) or the 6/7 genotype (36.1%; P = 0.002 by chi2). CONCLUSIONS: Genetic variation in the UGT1A promoter significantly influences serum bilirubin levels and the development of symptomatic cholelithiasis in children with SCA. The UGT1A promoter polymorphisms represent an important nonglobin genetic modifier of clinical disease expression in SCA.

Thrombophilic DNA Mutations As Independent Risk Factors for Stroke and Avascular Necrosis in Sickle Cell Anemia.

Thrombosis may be important in the pathophysiology of certain complications of sickle cell anemia (SCA), including cerebrovascular accident (CVA, stroke) and avascular necrosis (AVN). No single laboratory or clinical parameter can accurately identify patients who will develop these thrombotic complications. We hypothesized that a subset of patients with SCA have genetic thrombophilic mutations that increase the risk of stroke or AVN. We examined nine known thrombophilic DNA polymorphisms in α-fibrinogen, ß-fibrinogen, platelet glycoprotein IIIa, Factor VII, methylenetetra-hydrofolate reductase, plasminogen activator inhibitor-1, prothrombin, and Factor V genes in 101 African-American patients with SCA (27 CVA, 16 AVN). The allele frequency of thrombophilic mutations ranged from 0.0 (Prothrombin, Factor V) to 0.33 (α-fibrinogen). No mutation was significantly more common in patients with CVA or AVN than in patients without these complications. These nine thrombophilic mutations do not appear to be significant risk factors for the development of clinically overt CVA or AVN in SCA.

Palpable splenomegaly in children with haemoglobin SC disease: haematological and clinical manifestations.

This study aimed to investigate the prevalence of palpable splenomegaly in children with haemoglobin SC (Hb SC) disease, and to determine the haematological and clinical manifestations of splenomegaly in this patient population. We performed a retrospective chart review of 100 patients with Hb SC over 2 years of age followed by the Duke University Paediatric Sickle Cell Program with serial physical examinations and laboratory measurements. Palpable splenomegaly was present in 34% of patients and was more common in males (P = 0.029). Children with splenomegaly had a significantly lower average haemoglobin concentration (10.3 vs. 10.8 g/dl, P = 0.011) and lower platelet count (237 vs. 314 x 109/l, P < 0.001) than those without splenomegaly. Children with measurements both before and after the onset of splenomegaly had a significant decrease in the platelet count (279 vs. 216 x 109/l, P < 0.001) and white blood cell count (9.1 vs. 7.9 x 109/l, P = 0.04) after splenomegaly was identified. Clinical complications included acute splenic sequestration in 12% of children (median age 5.4 years), and hypersplenism with chronic thrombocytopenia in another 10% of patients (median age 10.6 years). Splenomegaly is a common physical finding in children with Hb SC disease and is often associated with mild cytopenias. Clinical complications of splenomegaly include acute splenic sequestration in younger patients and hypersplenism with chronic thrombocytopenia in older children.

Hydroxyurea as an alternative to blood transfusions for the prevention of recurrent stroke in children with sickle cell disease.

Children with sickle cell disease (SCD) and stroke receive chronic transfusions to prevent stroke recurrence. Transfusion risks including infection, erythrocyte allosensitization, and iron overload suggest a need for alternative therapies. We previously used hydroxyurea (HU) and phlebotomy in two young adults with SCD and stroke as an alternative to transfusions. We have now prospectively discontinued transfusions in 16 pediatric patients with SCD and stroke. Reasons to discontinue transfusions included erythrocyte alloantibodies or autoantibodies, recurrent stroke on transfusions, iron overload, noncompliance, and deferoxamine allergy. HU was started at 15 mg/kg/d and escalated to 30 mg/kg/d based on hematologic toxicity. Patients with iron overload underwent phlebotomy. The children have been off transfusions 22 months, (range, 3 to 52 months). Their average HU dose is 24.9 +/- 4.2 mg/kg/d, hemoglobin concentration is 9.4 +/- 1.3 g/dL, and mean corpuscular volume (MCV) is 112 +/- 9 fL. Maximum percentage fetal hemoglobin (%HbF) is 20.6% +/- 8.0% and percentage HbF-containing erythrocytes (%F cells) is 79.3% +/- 14.7%. Fourteen patients underwent phlebotomy with an average of 8,993 mL (267 mL/kg) removed. Serum ferritin has decreased from 2,630 to 424 ng/mL, and 4 children have normal ferritin values. Three patients (19%) had neurological events considered recurrent stroke, each 3 to 4 months after discontinuing transfusions, but before maximal HU effects. These preliminary data suggest some children with SCD and stroke may discontinue chronic transfusions and use HU therapy to prevent stroke recurrence. Phlebotomy is well-tolerated and significantly reduces iron overload. Modifications in HU therapy to raise HbF more rapidly might increase protection against stroke recurrence.

Hemoglobin S/O(Arab): thirteen new cases and review of the literature.

Hemoglobin S/O(Arab) (Hb S/O(Arab)) is a rare compound heterozygous hemoglobinopathy characterized by the presence of two variant beta-globin chains: beta6Glu --> Val (Hb S) and beta121Glu --> Lys (Hb O(Arab)). The diagnosis of Hb S/O(Arab) requires electrophoresis on both cellulose acetate and citrate agar, since Hb O(Arab) co-migrates with Hb C at alkaline pH and close to Hb S at acidic pH. To date only case reports and small series of patients with Hb S/O(Arab) have been described. To better characterize the clinical and laboratory aspects of this unusual disorder, we reviewed the Duke University Medical Center experience. We identified 13 African-American children and adults with Hb S/O(Arab) ranging in age from 2.7 to 62.5 years. All patients had hemolytic anemia with a median Hb of 8.7 gm/dL (range 6.1-9.9 gm/dL), and a median reticulocyte count of 5.8% (range 1.2-10.3%). The peripheral blood smear typically showed sickled erythrocytes, target cells, polychromasia, and nucleated red blood cells. All 13 patients have had significant clinical sickling events including acute chest syndrome (11), recurrent vasoocclusive painful events (10), dactylitis (7), gallstones (5), nephropathy (4), aplastic crises (2), avascular necrosis (2), leg ulcers (2), cerebrovascular accident (CVA) (1), osteomyelitis (1), and retinopathy (1). Four patients have died, including two from pneumococcal sepsis/meningitis at ages 5 and 10 years, one of acute chest syndrome at age 14 years, and one of multiorgan failure at age 35 years. We conclude that Hb S/O(Arab) disease is a severe sickling hemoglobinopathy with laboratory and clinical manifestations similar to those of homozygous sickle cell anemia.

Erythrocyte autoantibodies in paediatric patients with sickle cell disease receiving transfusion therapy: frequency, characteristics and significance.

The formation of erythrocyte autoantibodies following transfusion therapy has been described in case reports and small series. To determine the frequency, serological characteristics, and clinical significance of this phenomenon in paediatric patients with sickle cell disease, we analysed the patient database at the Duke University Pediatric Hematology Clinic. We identified children who received multiple erythrocyte transfusions, then reviewed clinical records to identify children who developed erythrocyte autoantibodies in association with transfusions. Among 184 paediatric patients who received multiple erythrocyte transfusions, 14 children (7.6%) developed warm (IgG) erythrocyte autoantibodies. Median transfusion exposure at the time of autoantibody formation was 24 erythrocyte units, range 3-341 units. The autoantibody reacted as a panagglutinin in 11 cases but had anti-e specificity in three patients. Surface complement also was detected in five patients. Clinically significant haemolysis was documented in four patients, each of whom had both surface IgG and C3 detected. The development of erythrocyte autoantibodies was associated with the presence of erythrocyte alloantibodies. Formation of warm erythrocyte autoantibodies in association with transfusions is not rare in paediatric patients with sickle cell disease. Clinicians should be aware of this complication and recognize that the presence of surface C3 is often associated with significant haemolysis.

Inherited DNA mutations contributing to thrombotic complications in patients with sickle cell disease.

Thrombosis may play an important role in the pathophysiology of certain complications of sickle cell disease (SCD), including stroke and avascular necrosis (AVN). Currently there is no laboratory or clinical parameter that can identify patients who are at highest risk of developing these thrombotic complications. We hypothesized that some patients with SCD have an inherited hypercoagulable state that results in an increased risk of developing stroke or AVN. We examined the role of two common inherited thrombophilic mutations that, in other populations, have been associated with arterial and venous thrombosis and are amenable to screening with DNA restriction enzyme analysis. The C677T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene and the C1565T mutation in the platelet glycoprotein IIIa (GPIIIa) gene were evaluated. We analyzed genomic DNA from 86 children and adults with SCD, including 16 patients with a history of a clinical stroke and 14 patients with AVN, for the presence of these mutations. The C677T MTHFR mutation was found in 19% of patients with stroke, 14% of patients with AVN, and 14% of patients with neither complication (P = NS). The C1565T GPIIIa mutation was found in 25% of patients with stroke, 14% of patients with AVN, and 18% of patients with neither complication (P = NS). Although each of these mutations is relatively common in patients with SCD, neither is independently associated with an increased risk of developing stroke or AVN.

Identification of mutations and polymorphisms in the factor XI genes of an African American family by dideoxyfingerprinting.

Congenital deficiency of factor XI is a rare condition associated with a mild to moderate bleeding diathesis that is most commonly found in persons of Jewish ancestry. The disorder has been reported sporadically in a number of other ethnic groups, but rarely in the black population. We report on the genetic analysis of the factor XI genes of two African American patients: a 9-year-old boy (the propositus) with mild factor XI deficiency and his mother. Both individuals have lifelong histories of excessive bleeding. Dideoxyfingerprinting, a technique combining components of single-strand conformational polymorphism analysis and dideoxy-chain termination sequencing, was used in the analysis. Both patients were found to be heterozygous for a mutation changing serine 248 to asparagine [corrected], whereas the propositus was heterozygous for an additional mutation on the paternal allele changing glutamine 226 to arginine. Both mutations reside in the third apple domain of the factor XI heavy chain, an area that has been shown to contain binding sites for factor IX, platelets, and glycosaminoglycans. Previously reported mutations in the factor XI gene seem to cause deficiency primarily by reducing protein expression. Because both alleles in the propositus contain amino acid substitutions, the significant amount of circulating factor XI in his plasma must be comprised entirely of abnormal molecules. Factor XI circulates as a homodimer, and the presence of mutations in both alleles of the factor XI gene suggests that his bleeding disorder is caused in part by the effect of the two abnormal gene products forming dimers in different combinations. Three neutral (not associated with amino acid changes) DNA polymorphisms were also identified in the two subjects: a C to T change at nucleotide 472 in exon 5, A to G at nucleotide 844 in exon 8, and T to C at nucleotide 1234 in exon 11. Analysis of a random sample of normal volunteers showed that these polymorphisms are relatively common, with allele frequencies of 7.4%, 19%, and 18%, respectively. This suggests that there is considerable genetic heterogeneity in the factor XI gene.

Anti-D: mechanisms of action.

Immunoglobulin that recognizes and binds specifically to the erythrocyte D antigen (anti-D globulin, WinRho SDF; Nabi, Boca Raton, FL) has recently been shown to be an effective therapy for many patients with idiopathic thrombocytopenic purpura (ITP). Its mechanisms of action are not completely understood. Intravenous (IV) infusion of anti-D into a D-positive recipient leads to antibody coating of circulating erythrocytes that are cleared primarily by the spleen. This immune-mediated clearance of sensitized erythrocytes occupies the reticuloendothelial system and allows survival of antibody-coated platelets. Based on clinical observations, experimental data, and theoretical calculations, the efficacy of anti-D therapy in ITP depends on several factors that influence the amount of erythrocyte sensitization and the rate of immune-mediated erythrocyte clearance by the spleen. Antibody characteristics, including the antibody concentration, binding affinity, and dissociation constants, may be important, as well as the number of D-antigen binding sites on the erythrocytes. Although the primary mechanism of action of anti-D is believed to be immunologic blockade of Fc receptors (FcR) within the reticuloendothelial system (RES), other immunomodulatory effects are also possible.

Immunologic effects of anti-D (WinRho-SD) in children with immune thrombocytopenic purpura.

Intravenous immunoglobulin (IVIG) is an effective treatment for immune thrombocytopenic purpura (ITP) that induces transient blockade of the reticuloendothelial system (RES) with additional effects including alteration of T lymphocyte subsets and suppression of in vitro T lymphocyte proliferation. As anti-D also is an effective treatment for ITP, we investigated its in vitro and in vivo immunologic effects. The in vitro effects of various agents used in ITP therapy were compared using T lymphocyte proliferation assays. Anti-D caused significantly less inhibition than IVIG or dexamethasone, but non-specific protein was as suppressive as IVIG. Six children with chronic ITP were studied following anti-D administration. Patients received a single dose of anti-D (WinRho-SD, 50 microg/kg i.v. over 5 min) and were studied on day 0, day 7, and 1 month later. Anti-D did not affect T lymphocyte subsets including the T cell receptor variable beta repertoire, in vitro T lymphocyte proliferation to mitogens, recall antigens, or interleukin-2, in vitro IgG synthesis induced by pokeweed mitogen, or T lymphocyte cytokine mRNA levels. We conclude that anti-D has no demonstrable in vitro or in vivo effects on lymphocyte enumeration or function, and therefore likely is effective in the treatment of ITP primarily through RES blockade.

Glucose-6-phosphate dehydrogenase Durham: a de novo mutation associated with chronic hemolytic anemia.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common X-linked enzyme defect. We report a new variant, G6PD Durham713G, that is associated with chronic nonspherocytic hemolytic anemia. The G6PD Durham713G variant has a unique biochemical and enzymatic profile and a novel A-->G substitution mutation at nucleotide 713, changing lysine to arginine at amino acid 238. This mutation was not found in the mother of our patient, indicating that G6PD Durham713G resulted from a de novo mutation.

Clinical significance of the antinuclear antibody test in selected children with idiopathic thrombocytopenic purpura.

PURPOSE: To determine the clinical significance of the antinuclear antibody (ANA) test in selected children with idiopathic thrombocytopenic purpura (ITP). METHODS: The study was conducted through retrospective chart review and long-term follow-up by telephone interview. RESULTS: Of 87 children with ITP who had an ANA performed, 25 had a positive titer (median = 1:160, range: 1:40 to 1:2,560). Children with a positive ANA were more likely to be older girls who developed chronic ITP, but there was no correlation with family history of autoimmune disease, initial hemoglobin concentration, or initial platelet count. With an average follow-up of more than 5 years, more children with a positive ANA developed further autoimmune symptoms than those with a negative ANA (36% vs. 0%, p < 0.001). Nine children with a positive ANA developed additional autoimmune symptoms, including five with clinical criteria sufficient for the diagnosis of systemic lupus erythematosus (SLE). Autoantibodies to dsDNA were more prevalent in the children with progression of autoimmune symptoms (57% vs. 0%, p = 0.04). The presence of any autoantibody in addition to the ANA, including dsDNA, SS-A/Ro, SS-B/La, Smith Antigen (Sm), nuclear ribonucleoprotein (nRNP), or cardiolipin was more common in children who had further autoimmune symptoms (75% vs. 0%, p = 0.003). CONCLUSIONS: The ANA is a useful screening test in a subset of children with ITP, especially older girls with chronic ITP, who are at risk for the development of generalized autoimmune disease. Children with ITP and a positive ANA should receive careful follow-up.

Laser hazard evaluation method for middle infrared laser systems.

Hazard evaluation methods for lasers, with wavelengths greater than 1.4 microns (mostly in the middle infrared), have changed significantly in the current version of the American National Standard for the Safe Use of Lasers, ANSI Z136.1-1993. A correct evaluation involves comparing the hazard potential based on two evaluation models; one based on individual pulses and the other based on an equivalent continuous-wave exposure. An example of the hazard evaluation method within this spectral region is provided.