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Educational preparedness of veterinarians for foreign animal diseases.

Veterinary medical education in FADs has been and will continue to be critically important if veterinarians are expected to fulfill the profession's primary obligations to society--those of protecting our animals' health, conserving our animal resources, and promoting public health. It is imperative that curricula and instruction in veterinary schools and colleges provide the depth and breadth of knowledge and understanding necessary to prepare all veterinarians, including those in private practice, for their key role in defending against FADs. Development and implementation of governmental and military programs to diagnose, prevent, control, and eradicate FADs will require a dedicated cadre of public sector veterinarians who have a solid educational foundation in FADs and understand the contemporary issues and global challenges we face. Animal-related industries, associations, and organizations will increasingly rely on well-educated veterinarians to help guide them in ways that will protect animals, clientele, consumers, and trading partners from effects of FADs. Agencies and organizations concerned with conservation of animal resources will require veterinary expertise necessary to prevent FADs in a multitude of animal species, including marine animals, wildlife, endangered species, zoologic specimens, and important genetic lines as well as our domestic companion and livestock species. Species affected by FADs also include human beings for those disease agents with zoonotic potential; thus, veterinary education also plays a key role in public health.

Accreditation↗

Fetal activity acceleration during early labor.

Altogether 59 women (53 normal and 6 high-risk pregnancies) underwent a fetal activity acceleration determination (FAD) during the first stage of labor. 52 FAD were considered reactive, while 5 were non-reactive and 2 technically inadequate. Four of the 5 fetuses with a non-reactive FAD showed signs of fetal compromise during labor and 1 died intra-uterinely. There were significantly more normal births and non-compromised fetuses in the FAD reactive group than in the non-reactive (p less than 0.002, chi 2-test), while there were significantly more acute cesarean sections in the non-reactive group (p less than 0.001, chi 2-test). Of the 12 vacuum extractions (all in the FAD reactive group) 4 were performed because of prolonged 2nd stage and 8 because of suspected because of prolonged 2nd stage and 8 because of suspected intra-uterine asphyxia, but all infants did well after delivery, and the umbilical arterial pH was in all cases above 7.15. It is concluded that when a FAD test is reactive in the first stage of labor, one can expect a positive outcome of the birth, whereas a non-reactive test arouses suspicion of fetal compromise and implies that one must carefully monitor the progress of the birth so that the fetus can be delivered promptly if any sign of late decelerations should appear. A reactive FAD is, on the other hand, rather reassuring for the fetal state.

Delivery, Obstetric↗

Catalytic properties of streptococcal NADH oxidase containing artificial flavins.

The flavoprotein NADH oxidase from Streptococcus faecalis 10C1, which catalyzes the tetravalent reduction of O2-->2H2O, has been purified as the apoenzyme to allow reconstitution studies with both native and artificial flavins. Turnover numbers for the enzyme containing 1-deaza-, 2-thio-, and 4-thio-FAD range from 51 to 4% of that of the native FAD enzyme; these reconstituted oxidases also catalyze the four-electron reduction of oxygen. Dithionite and NADH titrations of the native FAD oxidase require 1.7 eq of reductant/FAD and follow spectral courses very similar to those previously reported for the purified holoenzyme. Azide is a linear mixed-type inhibitor with respect to NADH, and dithionite titrations in the presence of azide yield significant stabilization of the neutral blue semiquinone. Redox stoichiometries for the oxidase containing modified flavins range from 1.1 to 1.4 eq of reductant/FAD. Spectrally distinct reduced enzyme.NAD+ complexes result with all but the 2-thio-FAD enzyme on titration with NADH. The reduced 4-thio-FAD oxidase shows little or no evidence of desulfurization to native FAD on reduction and reoxidation. Both the 8-mercapto- (E'o = -290 mV) and 8-hydroxy-FAD (E'o = -335 mV) oxidase are readily reduced by excess NADH. These results offer a further basis for analysis of the active-site structure and oxygen reactivity of this unique flavoprotein oxidase.

Amino Acid Sequence↗

Role of p53, CD44V6 and CD57 in differentiating between benign and malignant follicular neoplasms of the thyroid.

The distinction between follicular adenoma (FAD) and follicular carcinoma (FCA) of the thyroid can be particularly challenging in routine practice of diagnostic surgical pathology. It often requires examination of several histologic sections in order to identify the presence of unequivocal capsular and/or vascular invasion. To investigate the role of immunohistochemical markers in the differential diagnosis of follicular lesions of the thyroid, we studied the pattern of expression of p53, Bcl-2 and of the adhesion molecules CD44V6 and CD57, in 20 FADs and 21 FCAs of the thyroid. Ninety percent of FCAs exhibited strong nuclear p53 expression. p53 stain was seen in only 15% of FADs (p<0.0001), and it was weak. Bcl-2 cytoplasmic immunoreactivity was observed in 57% of FCAs and 60% of FADs (p=1.00). Similarly, membranous CD44V6 staining was seen in 81% of FCAs, but in only 20% of FADs (p=0.0001). CD57 was present in the cytoplasm of 71% of FCAs and 15% of FADs (p=0.0004). None of the markers studied correlated with tumor size. The results of this study indicate that immunohistochemical detection of p53, CD44V6 and CD57 may have practical utility in the differential diagnosis of FCAs from FADs in routine surgical pathology.

Adenocarcinoma, Follicular↗

Reactivity of chicken liver xanthine dehydrogenase containing modified flavins.

Native FAD was removed from chicken liver xanthine dehydrogenase (XDH) and replaced with a number of artificial flavins of different redox potential. Dithionite titration of the 2-thio-FAD- or 4-thio-FAD (high potential)-containing enzymes showed that the first center to be reduced was the flavin. With native enzyme, iron-sulfur centers are the first to be reduced. With the low potential flavin, 6-OH-FAD, the enzyme-bound flavin was the last center to be reduced in reductive titration with xanthine. These shifts in the reduction profile support the hypothesis that the distribution of reducing equivalents in multi-center oxidation-reduction enzymes of this type is determined by the relative potentials of the centers. The reaction of molecular oxygen with fully reduced 2-thio-FAD XDH or 4-thio-FAD XDH resulted in 5 electron eq being released in a fast phase and one in a slow phase. Reduction of these enzymes by xanthine was limited at a rate comparable to that for the release of urate from native XDH. Xanthine/O2 turnover with these enzymes (and native XDH) resulted in approximately 40-50% of the xanthine reducing equivalents appearing as superoxide. Steady state turnover experiments involving all modified flavin-containing enzymes, as well as native enzyme, showed that shifting the flavin potential either positive or negative relative to FAD caused a decrease in catalytic activity in the xanthine/NAD reductase reaction. In the case of the xanthine/O2 reductase activity, there is no simple obvious relationship between the activity and the redox potential of the reconstituted flavin.

Animals↗

Phagocyte NADPH-oxidase. Studies with flavin analogues as active site probes in triton X-100-solubilized preparations.

NADPH-oxidase of stimulated human neutrophil membranes was solubilized in Triton X-100 and activity reconstituted with FAD, 8-F-FAD, 8-phenyl-S-FAD, and 8-S-FAD. The enzyme had similar affinities for all the flavins with Km values in the 60-80 nM range. Vmax was found to increase 4-fold with increasing redox midpoint potential of the flavin. 8-F-FAD reconstituted with the enzyme was reactive toward thiophenol, suggesting exposure of the 8-position to solvent, a finding supported by unsuccessful attempts to label the enzyme with the photoaffinity probe 8-N3-[32P]FAD. Solubilized oxidase stabilized the red thiolate form of 8-S-FAD, a characteristic of flavoproteins of the dehydrogenase/electron transferase classes which stabilize the blue neutral form of the flavin semiquinone radical.

Cell Membrane↗

Reevaluation of cytochrome b and flavin adenine dinucleotide in neutrophils from patients with chronic granulomatous disease and description of a family with probable autosomal recessive inheritance of cytochrome b deficiency.

Chronic granulomatous disease (CGD) is a genetically heterogeneous syndrome characterized by a microbial killing defect of polymorphonuclear leukocytes (PMNs) due to lack of superoxide O2-. 2 generation. Recent studies indicate that the neutrophil O2-.-generating system consists of at least two components, flavoprotein--flavin adenine dinucleotide (FAD)--and cytochrome b. We evaluate the cytochrome b and FAD content in PMN from 30 CGD patients. The method for quantitating cytochrome b was modified by using PMN sonicates incubated with azide plus hydrogen peroxide. With this approach, several absorption peaks corresponding to myeloperoxidase and eosinophil peroxidase, which overlap with peaks of cytochrome b, were obliterated from reduced-minus-oxidized spectra, whereas the peaks of cytochrome b were not and could be readily quantitated. Cytochrome b was detected in PMNs from all 24 normal adults (47.4 +/- 2.9 pmol/7.5 X 10(6) cells), was absent in PMNs from 11 male CGD patients and one female CGD patient but was present in normal amounts in PMNs from nine male and nine female CGD patients. Stimulated nitroblue tetrazolium (NBT) tests performed on PMNs from mothers of CGD patients indicated that cytochrome b deficiency was associated with X-linked inheritance, except in one case in which probable autosomal recessive inheritance was demonstrated. The PMN NBT test of the mother of another male patient without cytochrome b deficiency suggested an X-linked form of inheritance. In related studies, the FAD content in PMN particulate fractions was reduced in 4 of 28 CGD patients studied. All four CGD patients with reduced FAD lacked cytochrome b. However, three patients with cytochrome b deficiency had normal FAD. Thus, the results indicate that PMN cytochrome b deficiency is observed in most X-linked and in some autosomal recessive CGD, that cytochrome b deficiency may be associated with FAD deficiency, and that cytochrome b and FAD are normal in most patients with non-X-linked CGD.

Adult↗

[The activity of enzymes involved in synthesis and hydrolysis of flavin adenine dinucleotide is Pichia guilliermondii studies at different levels of flavinogenesis].

The activity of FAD-pyrophosphorylase and FAD-hydrolase (nucleotidepyrophosphatase) was studied in extracts of Pichia guilliermondii ATCC 9058 capable of riboflavin over-production. The specific activity of the enzymes was highest at the logarithmic growth phase (2.6 and 3.8 mcmoles of FAD per 1 min per 1 mg of protein X10(-5), respectively), and did not increase upon the induction of riboflavin overproduction. A decrease in the content of hemin compounds and a low content of flavins in the cells of Pichia guilliermondii mutants had no considerable effect on the activity of the two enzymes. When the yeast was cultivated on a medium containing hexadecane, an increase in the content of FAD in the cells was not accompanied with a rise in the activity of FAD-pyrophosphorylase. The activity of the enzyme did not change when succinate and lactate, the substrates of FAD-containing enzymes, were used as the source of carbon. The activity of FAD-pyrophosphorylase increased only when iron-deficient cells of the yeast were grown or incubated on a medium containing glycine; this stimulation was inhibited by cycloheximide.

Ascomycota↗

Fetal activity determination and neosynephrine test for evaluation of fetal well-being in high risk pregnancies.

At the special outpatient clinic for high risk pregnancies, a total of 197 patients were evaluated with fetal activity acceleration determination (FAD) as a non stress test. FAD was done on 197 patients, of these there were 8 fetal distress (4.7%) and 3 low Apgar scores (1 minute Apgar score less than 6) (1.8%) of 169 positive FAD, on the other hand, 14 fetal distress (50%) and 10 low Apgar scores (35.7%) of 28 negative FAD. Neosynephrine Test was performed in 62 cases as a stress test and the correlation between these two tests was evaluated. In 51 instances FAD was positive and the simultaneous Neosynephrine Test was normal. In 2 cases of negative FAD with positive Neosynephrine Test, there were 2 fetal distress (100%) and 2 low Apgar scores (100%). All the two tests are reliable for fetal evaluation in high risk pregnancies, because FAD and Neosynephrine Test are less time consuming and have fewer contraindications. It is concluded that the combination of these two tests are the most useful screening methods for fetal evaluation in high risk pregnancies.

Evaluation Studies as Topic↗

2-Aminobenzoyl-CoA monooxygenase/reductase. Evidence for two distinct loci catalyzing substrate monooxygenation and hydrogenation.

2-Aminobenzoyl-CoA monooxygenase/reductase catalyzes both monooxygenation and hydrogenation of anthraniloyl-CoA. Its reactivity with 11 substrate analogs has been investigated. Only 2-aminobenzoyl-CoA (anthraniloyl-CoA) in its normal and deuterated (5-2H) form is a full substrate, and only traces of 2-hydroxybenzoyl-CoA (salicyloyl-CoA) are probably monooxygenated but not hydrogenated. The purified enzyme is a homodimer and has been resolved preparatively into three major species by anion-exchange chromatography on Mono Q. All three species have the same specific activity when reconstituted to full content of FAD, they differ, however, substantially in their mode of binding FAD. The oxidized or fully reduced enzyme forms bind tightly 0.5 mol/mol of the substrate 2-aminobenzoyl-CoA (Kd = 1-2 microM). The enzyme can be depleted of approximately 50% of its FAD, which corresponds to essentially complete removal from one of the two binding sites, reflecting a large difference in the affinity for FAD. From this it is deduced that the two sites are not equivalent. Removal of FAD from one binding site leads to loss of the hydrogenation capacity of the enzyme, while monooxygenation catalysis is retained. The FAD cofactors of the two binding sites differ drastically in their reactivities towards NADH, oxygen and N-ethylmaleimide. Exchange of reducing equivalents between the two FAD cofactors at the respective binding sites is very slow and irrelevant compared to the rates of catalysis. It is concluded that the enzyme, which has been proposed to consist of two identical polypeptide chains [Altenschmidt, U., Bokranz, M. & Fuchs, G. (1992) Eur. J. Biochem. 207, 715-722], contains two active centers which differ substantially in their catalytic activity. One center belongs to the class of monooxygenases, the other one to the (de)hydrogenases. This must result from substantially different interaction of the same flavin cofactors with protein functional groups and is, to our knowledge, unprecedented in flavoprotein enzymology.

Catalysis↗

Factor analysis for extraction of blood time-activity curves in dynamic FDG-PET studies.

UNLABELLED: Arterial sampling in dynamic PET studies can be eliminated by using left ventricular or aortic time-activity curves (TAC) obtained from user drawn regions of interest (ROIs) after appropriate spillover correction. In this study, we evaluated the feasibility of extracting the "pure" arterial TAC from dynamic PET images using factor analysis of dynamic structures (FADS). METHODS: Computer simulations were used to study the performance of the FADS algorithm with positivity constraints. Ten canine 13N-ammonia and two human FDG-PET dynamic studies were used to extract the blood TACs from FADS. Plasma samples and compartmental model fittings were used to validate the accuracy of the FADS-generated blood factors. RESULTS: We found that FADS with positivity constraints was sufficient to extract the blood factor from the composite dynamic images. The "pure" blood-pool TACs that matched well with the arterialized well counter measurements were generated from FADS in the canine and human studies. CONCLUSION: FADS has the potential to accurately extract "pure" blood TAC from dynamic PET images, allowing reliable quantitation of biological information from PET studies without blood sampling, ROI drawing or spillover correction.

Algorithms↗

Fetal activity acceleration determination for the evaluation of fetal reserve.

Fetal activity acceleration determination (FAD) was performed 462 times on a total of 410 patients for the evaluation of fetal reserve. Simultaneous oxytocin challenge test (OCT) was performed 324 times to evaluate the correlation between the two tests. In 308 instances, FAD was positive and OCT was either negative or probably negative. In 2 cases with inadequate FAD results the simultaneous OCT was suspicious and positive. In four instances of negative FAD the simultaneous OCT was positive. The correlation between the two tests was excellent. The outcome of all cases with positive FAD was also excellent. The result of the present study strongly suggests that the positive FAD indeed provides reassurance of fetal well-being. Only the inadequate or negative FAD requires the performance of an OCT for further evaluation of the fetal condition.

Delivery, Obstetric↗

Novel presenilin 1 mutation (S170F) causing Alzheimer disease with Lewy bodies in the third decade of life.

BACKGROUND: Cases of early-onset Alzheimer disease (AD) with an autosomal dominant inheritance pattern (familial AD [FAD]) are rare but have greatly advanced our understanding of the molecular pathogenesis of AD. We describe herein a kindred with very early-onset FAD (age, <40 years) with unusual pathological features and a novel mutation in the presenilin 1 (PSEN1) gene (S170F) and review the existing literature on very early-onset FAD. OBJECTIVE: To analyze the neuropathological and genetic features of a family with onset of AD in the third decade of life. DESIGN, SETTING, AND PARTICIPANTS: The proband underwent full clinical assessment and postmortem examination at the Washington University Alzheimer's Disease Research Center, St Louis, Mo. Limited pathological samples and autopsy records of 2 affected family members were available. The proband underwent screening for mutations in genes linked with FAD. RESULTS: Dementia developed in 3 family members in this kindred at a mean age of 27 years; the proband had myoclonus, seizures, and rigidity, similar to findings in previously described kindreds with PSEN1 mutations. All 3 family members were confirmed to have AD by neuropathological examination. The proband also had widespread Lewy body pathology in the brainstem, limbic areas, and neocortex; specific staining for Lewy bodies was not performed in the other 2 family members. The proband had a single mutation (S170F) in exon 6 of the PSEN1 gene, which segregates with disease. CONCLUSIONS: A novel PSEN1 mutation causes very-early-onset FAD with associated Lewy bodies. To our knowledge, this kindred has the earliest reported onset of pathologically confirmed FAD and dementia with Lewy bodies.

Adult↗

Abnormality of the alpha-ketoglutarate dehydrogenase complex in fibroblasts from familial Alzheimer's disease.

To test whether previously demonstrated reductions in the activity of the alpha-ketoglutarate dehydrogenase complex (KGDHC) in Alzheimer's disease (AD) brain also occur in morphologically normal AD tissues, we examined KGDHC in cultured skin fibroblasts from patients with familial AD (FAD). KGDHC activity was reduced by 44% in the FAD cells (p < 0.002) from the 4 families studied, including a within-kindred comparison of affected and escapee subjects in the chromosome 14q24.3-linked Nova Scotia kindred. The activities of several other glutamate- and glutamine-metabolizing enzymes were normal in the FAD cells, as was the activity of another mitochondrial multienzyme dehydrogenase complex, that for pyruvate. Mixing experiments indicated that the abnormality of KGDHC activity in FAD fibroblasts was not due to an inhibitor or to excess protease activity. KGDHC is a complex of three proteins. Immunoblots for the E2k component under conditions of optimal protease inhibition revealed the expected 46-kd species in both AD and non-AD fibroblasts, but the patient cells also regularly contained an additional 29-kd species that was absent or present in minimal amounts in the controls. Immunoblotting demonstrated no abnormalities in the E1k and E3 components. Other studies indicate that the human gene for E2k residues on chromosome 14q24.3, in a region associated with FAD in a number of families including the KGDHC-deficient Nova Scotia kindred. The persistence of abnormalities in KGDHC and particularly in its E2k component in FAD fibroblasts indicates that abnormalities of this autosomally coded nuclear component are an intrinsic part of the AD process, and the possible role of this abnormality in the pathogenesis of AD is discussed.

Alzheimer Disease↗

Crystal structure of glucose oxidase from Aspergillus niger refined at 2.3 A resolution.

Glucose oxidase (beta-D-glucose: oxygen 1-oxidoreductase, EC 1.1.3.4) is an FAD-dependent enzyme that catalyzes the oxidation of beta-D-glucose by molecular oxygen. The crystal structure of the partially deglycosylated enzyme from Aspergillus niger has been determined by isomorphous replacement and refined to 2.3 A resolution. The final crystallographic R-value is 18.1% for reflections between 10.0 and 2.3 A resolution. The refined model includes 580 amino acid residues, the FAD cofactor, six N-acetylglucosamine residues, three mannose residues and 152 solvent molecules. The FAD-binding domain is topologically very similar to other FAD-binding proteins. The substrate-binding domain is formed from non-continuous segments of sequence and is characterized by a deep pocket. One side of this pocket is formed by a six-stranded antiparallel beta-sheet with the flavin ring system of FAD located at the bottom of the pocket on the opposite side. Part of the entrance to the active site pocket is at the interface to the second subunit of the dimeric enzyme and is formed by a 20-residue lid, which in addition covers parts of the FAD-binding site. The carbohydrate moiety attached to Asn89 at the tip of this lid forms a link between the subunits of the dimer.

Amino Acid Sequence↗

Genetic heterogeneity of gene defects responsible for familial Alzheimer disease.

Inherited Alzheimer's disease is a genetically heterogeneous disorder that involves gene defects on at least five chromosomal loci. Three of these loci have been found by genetic linkage studies to reside on chromosomes 21, 19, and 14. On chromosomes 21, the gene encoding the precursor protein of Alzheimer-associated amyloid (APP) has been shown to contain several mutations in exons 16 and 17 which account for roughly 2-3% of familial Alzheimer's disease (FAD). The other loci include what appears to be a susceptibility gene on chromosome 19 associated with late-onset (> 65 years) FAD, and a major early-onset FAD gene defect on the long arm of chromosome 14. In other early- and late-onset FAD kindreds, the gene defects involved do not appear to be linked to any of these three loci, indicating the existence of additional and as of yet unlocalized FAD genes. This review provides a historical perspective of the search for FAD gene defects and summarizes the progress made in world-wide attempts to isolate and characterize the genes responsible for this disorder.

Alzheimer Disease↗

Presurgical localization of abnormal parathyroid glands using a single injection of technetium-99m methoxyisobutylisonitrile: comparison of different techniques including factor analysis of dynamic structures.

Single-tracer methoxyisobutylisonitrile (MIBI) imaging is considered to be a sensitive method for the localization of abnormal parathyroid glands. The aims of this study were to determine which of the analytical techniques described for this method - visual comparison of early (15-min) and late (120-min) images, use of time-activity curves (TACs) generated on regions of interest and factor analysis of dynamic structures (FADS) - corresponds best with surgical findings, and to ascertain the potential overall contribution of presurgical scintigraphy. Fifty-five patients were studied, 34 of whom presented with primary hyperparathyroidism (HPT) and 21 with secondary HPT. After a 925 MBq injection of technetium-99m MIBI, a 40-min dynamic acquisition was performed and static images were acquired at 5, 20, 40 and 120 min using a gamma camera equipped with a pinhole collimator. The dynamic series were submitted to FADS, an attractive non-operator-dependent technique, and TACs were generated on regions of interest after the visual comparison of early and 120-minute images (15'-120'). The presumed localizations of abnormal glands were compared with a sketch drawn by the surgeon. Sensitivity was defined as the percentage of true-positive localizations and was 84.4%, 74% and 65% in adenoma and 76%, 66.6% and 45% in hyperplasia for 15'-120', FADS and TACs, respectively. Surgical accuracy, i.e. the percentage of patients accurately and completely described, was 72%, 56% and 59% in adenoma and 53%, 30% and 22% in hyperplasia for 15'-120', FADS and TACs, respectively. The visual comparison method scored best in all cases. FADS was found to be sensitive in cases of adenoma but was handicapped by more false-positive localizations. TACs were particular inefficient in hyperplasia. With respect to the detection of adenomas, we found a relationship between the gland weight and scintigraphic positivity. This dependence on gland weight was not found in hyperplasia. The poorer results obtained with all techniques for surgical accuracy can be explained by the need for a complete scintigraphic description of all pathological glands found by the surgeon in a patient. This study demonstrates that the 15'-120' visual comparison method is more efficient and less cumbersome than TAC or the attractive FADS technique. However, it was less efficient than neck exploration by an experienced surgeon. Therefore, in our institution, scintigraphic studies are now only requested in selected cases of HPT, usually primary HPT and cases undergoing re-operation.

Adenoma↗

Site-specific immobilization of flavin adenine dinucleotide on indium/tin oxide electrodes through flavin adenine amino group.

A Mannich-type reaction was used to attach flavin adenine dinucleotide (FAD) covalently to aminosilane derivatized indium/tin oxide-coated glass plates. The aminosilane was activated with formaldehyde to give an intermediate that attached specifically to the adenine amino group of FAD. The presence of the intermediate also was demonstrated by coupling hydroquinone to the formaldehyde activated support. The immobilized FAD and hydroquinone were characterized by cyclic or differential pulse voltammetry. The immobilized FAD was shown to reduce the overpotential for NADH oxidation by 180 mV. In keeping with results for FAD on glassy carbon, FAD attached to indium/tin oxide at the adenine amino group did not lead to reconstitution of activity with apoglucose oxidase.

Apoenzymes↗