BRCA2 in American families with four or more cases of breast or ovarian cancer: recurrent and novel mutations, variable expression, penetrance, and the possibility of families whose cancer is not attributable to BRCA1 or BRCA2

In order to evaluate the role of inherited BRCA2 mutations in American families--particularly the appearance in America of European founder mutations--the BRCA2 coding sequence, 5' UTR, and 3' UTR were screened in 22 Caucasian American kindreds with four or more cases of breast or ovarian cancer. Six mutations were found that cause a premature-termination codon; four of them have been reported elsewhere, and two are novel. In the four families with previously seen mutations, the distinct lineages at high risk of cancer were of Dutch, German, Irish, and Ashkenazi Jewish ancestry; mutations in Europe reflect these ancestries. The families with novel mutations were Puerto Rican Hispanic (exon 9 deletion 995delCAAAT) and Ashkenazi Jewish (exon 11 deletion 6425delTT). Among female BRCA2-mutation carriers, risks of breast cancer were 32% by age 50 years, 67% by age 70 years, and 80% by age 90 years, yielding a lifetime risk similar to that for BRCA1 but an older distribution of ages at onset. BRCA2 families also included multiple cases of cancers of the male breast (six cases), ovary (three cases), fallopian tube (two cases), pancreas (three cases), bladder (two cases), and prostate (two cases). Among 17 Ashkenazi Jewish families with four or more breast or ovarian cancers, 9 families (including 3 with ovarian cancer and 1 with male breast cancer) carried none of the three ancient mutations in BRCA1 or BRCA2. To date, both BRCA2 and BRCA1 have been screened by SSCA, supplemented by the protein-truncation test, in 48 families with four or more breast or ovarian cancers. Mutations have been detected in BRCA1 in 33 families, in BRCA2 in 6 families, and in neither gene in 9 families, suggesting both the probable cryptic nature of some mutations and the likelihood of at least one other BRCA gene.

Time-dependent disposition of tacrolimus and its effect on endothelin-1 in liver allograft recipients

STUDY OBJECTIVE

To characterize a time-dependent disposition of oral tacrolimus and its relationship with plasma endothelin-1 concentrations.

DESIGN

Randomized, crossover study.

SETTING

Clinical research center of a university-affiliated hospital.

PATIENTS

Twelve stable liver transplant recipients.

INTERVENTIONS

In the steady state, 23 blood samples were taken from each patient before and after tacrolimus administration over 24 hours.

MEASUREMENTS AND MAIN RESULTS

Whole blood samples for tacrolimus and plasma endothelin-1 were analyzed by enzyme immunoassay. The relationship of their concentrations and their pharmacokinetic parameters between morning and evening doses were compared. The area under the curve (AUC) of tacrolimus in the morning dose was significantly larger than that in the evening dose (219 +/- 54 ng.hr/ml and 188 +/- 57 ng.hr/ml, respectively, p = 0.004). The mean time to peak concentration (Tmax) was significantly shorter for the morning dose than for the evening dose (1.6 +/- 0.7 hrs and 3.5 +/- 2.9 hrs, respectively, p = 0.01). The mean peak concentration (Cmax) was significantly higher in the morning dose than in the evening dose (32.2 +/- 9.1 ng/ml and 21.6 +/- 8.3 ng/ml, respectively, p = 0.008). However, the mean through concentration (Cmin) was not significantly different between doses. Endothelin-1 concentrations followed the same pattern as tacrolimus, with AUC and Cmax for the morning significantly higher than those for the evening dose of tacrolimus (AUC 13.8 +/- 3.7 pg.hr/ml, morning, and 11.0 +/- 3.5 pg.hr/ml, evening, p = 0.005; Cmax 2.4 +/- 1.1 pg/ml morning, and 1.5 +/- 0.6 pg/ml evening, p = 0.02). Tacrolimus levels did not correlate with endothelin-1 levels (r2 = 0.06, p = 0.001).

CONCLUSIONS

Tacrolimus disposition in liver transplant patients is determined by time of administration. Plasma endothelin-1 concentrations follow the same pattern as blood tacrolimus concentrations.

Determination of Binding of Bacillus thuringiensis (delta)-Endotoxin Receptors to Rice Stem Borer Midguts

Insecticidal activity and receptor binding properties of Bacillus thuringiensis toxins to yellow and striped rice stem borers (Sciropophaga incertulas and Chilo suppresalis, respectively) were investigated. Yellow stem borer (YSB) was susceptible to Cry1Aa, Cry1Ac, Cry2A, and Cry1C toxins with similar toxicities. To striped stem borer (SSB), Cry1Ac, Cry2A, and Cry1C were more toxic than Cry1Aa toxin. Binding assays were performed with (sup125)I-labeled toxins (Cry1Aa, Cry1Ac, Cry2A, and Cry1C) and brush border membrane vesicles (BBMV) prepared from YSB and SSB midguts. Both Cry1Aa and Cry1Ac toxins showed saturable, high-affinity binding to YSB BBMV. Cry2A and Cry1C toxins bound to YSB BBMV with relatively low binding affinity but with high binding site concentration. To SSB, both Cry1Aa and Cry1Ac exhibited high binding affinity, although these toxins are less toxic than Cry1C and Cry2A. Cry1C and Cry2A toxins bound to SSB BBMV with relatively low binding affinity but with high binding site concentration. Heterologous competition binding assays were performed to investigate the binding site cross-reactivity. The results showed that Cry1Aa and Cry1Ac recognize the same binding site, which is different from the Cry2A or Cry1C binding site in YSB and SSB. These data suggest that development of multitoxin systems in transgenic rice with toxin combinations which recognize different binding sites may be useful in implementing deployment strategies that decrease the rate of pest adaptation to B. thuringiensis toxin-expressing rice varieties.

ALS-linked SOD1 mutant G85R mediates damage to astrocytes and promotes rapidly progressive disease with SOD1-containing inclusions

High levels of familial Amyotrophic Lateral Sclerosis (ALS)-linked SOD1 mutants G93A and G37R were previously shown to mediate disease in mice through an acquired toxic property. We report here that even low levels of another mutant, G85R, cause motor neuron disease characterized by an extremely rapid clinical progression, without changes in SOD1 activity. Initial indicators of disease are astrocytic inclusions that stain intensely with SOD1 antibodies and ubiquitin and SOD1-containing aggregates in motor neurons, features common with some cases of SOD1 mutant-mediated ALS. Astrocytic inclusions escalate markedly as disease progresses, concomitant with a decrease in the glial glutamate transporter (GLT-1). Thus, the G85R SOD1 mutant mediates direct damage to astrocytes, which may promote the nearly synchronous degeneration of motor neurons.

Assessment of normal and mutant human presenilin function in Caenorhabditis elegans

We provide evidence that normal human presenilins can substitute for Caenorhabditis elegans SEL-12 protein in functional assays in vivo. In addition, six familial Alzheimer disease-linked mutant human presenilins were tested and found to have reduced ability to rescue the sel-12 mutant phenotype, suggesting that they have lower than normal presenilin activity. A human presenilin 1 deletion variant that fails to be proteolytically processed and a mutant SEL-12 protein that lacks the C terminus display considerable activity in this assay, suggesting that neither presenilin proteolysis nor the C terminus is absolutely required for normal presenilin function. We also show that sel-12 is expressed in most neural and nonneural cell types in all developmental stages. The reduced activity of mutant presenilins and as yet unknown gain-of-function properties may be a contributing factor in the development of Alzheimer disease.

Involvement of two amino acid residues in the loop region of Bacillus thuringiensis Cry1Ab toxin in toxicity and binding to Lymantria dispar

Two amino acids, Gly and Ser, at positions 282 and 283 in the loop region of domain II of Cry1Ab2 toxin are substituted with Ala and Leu in the Cry1Ab9-033 toxin. Cry1Ab2 exhibited about a 10-fold increase in toxicity and a 9-fold increase in binding affinity to Lymantria dispar compared to Cry1Ab9-033. However, these toxins showed similar toxicity and binding affinity to Manduca sexta and Spodoptera exigua. Heterologous competition assays and brush border membrane vesicle (BBMV) ligand blotting experiments demonstrated that Cry1Ab2 and Cry1Ab9-033 toxins recognized the same 210-kDa L dispar BBMV protein. No measurable differences in dissociation binding assays were observed between these two toxins. Digestion of these toxins with L dispar gut enzymes and BBMV proteases indicated no differences in stability. Ala and Leu residues in Cry1Ab9-033 were substituted with Gly and Ser by site-directed mutagenesis to produce mutant Cry1Ab alpha 8. This toxin exhibited full recovery of toxicity and binding affinity for L dispar. These data suggested that the residues Gly and Ser in the loop region might be directly involved in receptor binding and toxicity in L dispar.

Expression of presenilin 1 and 2 (PS1 and PS2) in human and murine tissues

Mutations in genes encoding related proteins, termed presenilin 1 (PS1) and presenilin 2 (PS2), are linked to the majority of cases with early-onset familial Alzheimer's disease (FAD). To clarify potential function(s) of presenilins and relationships of presenilin expression to pathogenesis of AD, we examined the expression of PS1 and PS2 mRNA and PS1 protein in human and mouse. Semi-quantitative PCR of reverse-transcribed RNA (RT-PCR) analysis revealed that PS1 and PS2 mRNA are expressed ubiquitously and at comparable levels in most human and mouse tissues, including adult brain. However, PS1 mRNA is expressed at significantly higher levels in developing brain. In situ hybridization studies of mouse embryos revealed widespread expression of PS1 mRNA with a neural expression pattern that, in part, overlaps that reported for mRNA encoding specific Notch homologs. In situ hybridization analysis in adult mouse brain revealed that PS1 and PS2 mRNAs are enriched in neurons of the hippocampal formation and entorhinal cortex. Although PS1 and PS2 mRNA are expressed most prominently in neurons, lower but significant levels of PS1 and PS2 transcripts are also detected in white matter glial cells. Moreover, cultured neurons and astrocytes express PS1 and PS2 mRNAs. Using PS1-specific antibodies in immunoblot analysis, we demonstrate that PS1 accumulates as approximately 28 kDa N-terminal and approximately 18 kDa C-terminal fragments in brain. Immunocytochemical studies of mouse brain reveal that PS1 protein accumulates in a variety of neuronal populations with enrichment in somatodendritic and neuropil compartments.

Epitope mapping of preS2 of the hepatitis B virus surface antigen against a conformation-dependent monoclonal antibody using synthetic peptides

Previously we reported that the N-terminal sequence 120/123-129 of the preS2 region of the hepatitis B virus surface antigen plays an important role on peptide antigenicity against a monoclonal antibody H8 (H8 mAb) by affecting the B cell epitope conformation of a peptide existing within the sequence 130-145 (Lee et al., Biochem. Mol. Biol. Int., 34, 159-168, 1994). In this study, we try to map the H8 mAb binding site using a series of substituted peptides in the sequence 131-143 by competitive ELISA. Peptide antigenicities were greatly reduced when the residues 131 (L), 137 (R), 140 (Y), 141 (F) and 142 (P) were substituted. The residues 133 (D), 134 (P) and 136 (V) had a slight affect on the mAb binding, whereas the residues 135 (R) and 139 (L) had no effects on the mAb binding. In contrast to H8 mAb, however, three anti-HBsAg polyclonal antisera showed the lowest bindings to the peptide substituted at position 135. These results suggest that the epitope against H8 mAb is discontinuously conformational.

A vector for expressing foreign genes in the brains and hearts of transgenic mice

An expression plasmid (MoPrP.Xho), for use in transgenic mice, was developed from the promoter, 5' intronic, and 3' untranslated sequences of the murine prion protein gene. Analyses of mice harboring the MoPrP.Xho construct with cDNA genes encoding the amyloid precursor protein (APP) and human presenilin 1 demonstrated that this vector provides relatively high levels of transgene-encoded polypeptides in brains and hearts of transgenic mice. The MoPrP.Xho vector should be very useful in strategies designed to overexpress a variety of wild-type and disease related mutant transgenes in the heart and brain.

Probing the mechanism of action of Bacillus thuringiensis insecticidal proteins by site-directed mutagenesis--a minireview

The current model of the mechanism of action of several Bacillus thuringiensis insecticidal crystal proteins (Cry) is reviewed and tested by site-directed mutagenesis experiments. Amino acid (aa) residues were substituted in each of the three domains of Cry toxins and the effects on toxin stability, binding to receptors, irreversible insertion into the membrane, and ion channel activity were examined. Mutant proteins with aa altered on the putative membrane-proximal surface of domain I are affected in insertion into the membrane and toxicity, but not in binding to the receptor. Alterations in the putative receptor-binding loops of domain II show an effect on the initial (reversible) binding to the receptor when certain aa are altered, while affecting irreversible binding when other aa are altered. Mutant proteins with aa altered in a conserved track of aa of domain III have altered ion channel properties, as measured by the voltage clamping of insect midguts and the K+ permeability of brush border membrane vesicles. In summary, domain I is involved in insertion into the membrane and affects ion channel function, domain II is involved in receptor binding and insertion into the membrane, and domain III is involved ion channel function, receptor binding, and insertion into the membrane.

Familial Alzheimer's disease-linked presenilin 1 variants elevate Abeta1-42/1-40 ratio in vitro and in vivo

Mutations in the presenilin 1 (PS1) and presenilin 2 genes cosegregate with the majority of early-onset familial Alzheimer's disease (FAD) pedigrees. We now document that the Abeta1-42(43)/Abeta1-40 ratio in the conditioned media of independent N2a cell lines expressing three FAD-linked PS1 variants is uniformly elevated relative to cells expressing similar levels of wild-type PS1. Similarly, the Abeta1-42(43)/Abeta1-40 ratio is elevated in the brains of young transgenic animals coexpressing a chimeric amyloid precursor protein (APP) and an FAD-linked PS1 variant compared with brains of transgenic mice expressing APP alone or transgenic mice coexpressing wild-type human PS1 and APP. These studies provide compelling support for the view that one mechanism by which these mutant PS1 cause AD is by increasing the extracellular concentration of Abeta peptides terminating at 42(43), species that foster Abeta deposition.

Neurofilament subunit NF-H modulates axonal diameter by selectively slowing neurofilament transport

To examine the mechanism through which neurofilaments regulate the caliber of myelinated axons and to test how aberrant accumulations of neurofilaments cause motor neuron disease, mice have been constructed that express wild-type mouse NF-H up to 4.5 times the normal level. Small increases in NF-H expression lead to increased total neurofilament content and larger myelinated axons, whereas larger increases in NF-H decrease total neurofilament content and strongly inhibit radial growth. Increasing NF-H expression selectively slow neurofilament transport into and along axons, resulting in severe perikaryal accumulation of neurofilaments and proximal axonal swellings in motor neurons. Unlike the situation in transgenic mice expressing modest levels of human NF-H (Cote, F., J.F. Collard, and J.P. Julien. 1993. Cell. 73:35-46), even 4.5 times the normal level of wild-type mouse NF-H does not result in any overt phenotype or enhanced motor neuron degeneration or loss. Rather, motor neurons are extraordinarily tolerant of wild-type murine NF-H, whereas wild-type human NF-H, which differs from the mouse homolog at > 160 residue positions, mediates motor neuron disease in mice by acting as an aberrant, mutant subunit.

Complete genomic sequence and analysis of 117 kb of human DNA containing the gene BRCA1

Over 100 distinct disease-associated mutations have been identified in the breast-ovarian cancer susceptibility gene BRCA1. Loss of the wild-type allele in > 90% of tumors from patients with inherited BRCA1 mutations indicates tumor suppressive function. The low incidence of somatic mutations suggests that BRCA1 inactivation in sporadic tumors occurs by alternative mechanisms, such as interstitial chromosomal deletion or reduced transcription. To identify possible features of the BRCA1 genomic region that may contribute to chromosomal instability as well as potential transcriptional regulatory elements, a 117,143-bp DNA sequence encompassing BRCA1 was obtained by random sequencing of four cosmids identified from a human chromosome 17 specific library. The 24 exons of BRCA1 span an 81-kb region that has an unusually high density of Alu repetitive DNA (41.5%), but relatively low density (4.8%) of other repetitive sequences. BRCA1 intron lengths range in size from 403 bp to 9.2 kb and contain the intragenic microsatellite markers D17S1323, D17S1322, and D17S855, which localize to introns 12, 19, and 20, respectively. In addition to BRCA1, the contig contains two complete genes: Rho7, a member of the rho family of GTP binding proteins, and VAT1, an abundant membrane protein of cholinergic synaptic vesicles. Partial sequences of the 1A1-3B B-box protein pseudogene and IFP 35, an interferon induced leucine zipper protein, reside within the contig. An L21 ribosomal protein pseudogene is embedded in BRCA1 intron 13. The order of genes on the chromosome is: centromere-1FP 35-VAT1-Rho7-BRCA1-1A1-3B-telomere.

Structure-biological activity relationships of 11-residue highly basic peptide segment of bovine lactoferrin

The antimicrobial peptide, lactoferricin, is generated upon the gastric pepsin cleavage of lactoferrin and has many basic and hydrophobic amino acid residues essential for its biological activity. To investigate the structure-antimicrobial activity relationships, the basic amino acid-rich region of bovine lactoferricin (BLFC), RRWQWRMKKLG, was selected. Using chemically synthesized BLFC and its substituted peptides, the antimicrobial activities of the peptides were tested by determining the minimal inhibitory concentration (MIC) of Escherichia coli and Bacillus subtilis and the disruption of the outer cell membrane of E. coli, and the peptide's toxicities were assayed by hemolysis. The short peptide (B3) composed of only 11 residues had similar antimicrobial activities while losing most of the hemolytic activities as compared with the 25 residue-long ones (B1 and B2). The short peptides (B3, B5 and B7) with double arginines at the N-termini had more potent antimicrobial activity than those (B4 and B6) with lysine. However, no antimicrobial and hemolytic activities were found in B8, in which all basic amino acids were substituted with glutamic acid, and in B9, in which all hydrophobic amino acids were substituted with alanine. The circular dichroism (CD) spectra of the short peptides in 30 mM SDS were correlated with their antimicrobial activities. These results suggested that the 11-residue peptide of BLFC is involved in the interaction with bacterial phospholipid membranes and plays an important role in antimicrobial activity with little or no hemolytic activity.

An unusual case of monozygotic epigastric heteropagus twinning

Epigastric heteropagus refers to unequal and asymmetric conjoined twins in which the dependent component (parasite) is smaller and usually attached to the epigastrium of the dominant component (autosite). Epigastric heteropagus is a very rare type of conjoined twins. It is generally assumed that conjoined twins represent a form of monozygotic twinning, but there has been no confirmation of this monozygotic hypothesis. Epigastric heteropagus twins differ in several ways from symmetrical conjoined twins. These include male preponderance, and no major connection of vessels, bowels, or bones. These significant characteristics suggest to the authors that the fusion of two fertilized ova and the atrophy of one fetus resulted in this interesting malformation. However, a DNA study indicated monozygotic origin in their case. The possible pathogenesis was ischemic atrophy of the body structure of the monozygotic conjoined twins at an early gestational age.

Inherited neurodegenerative diseases and transgenic models

In recent years, the identification of mutations in specific genes in several inherited neurodegenerative disorders, combined with advances in the field of transgenic methods, has provided neuroscientists and neuropathologists with information and strategies to develop transgenic (Tg) models to study human diseases. These approaches have proved to be extraordinarily useful in modeling familial forms of amyotrophic lateral sclerosis (FALS) and Alzheimer's disease (FAD) and the spectrum of triplet-repeat disorders. Investigations of these models have begun to provide new insights into the roles of disease-specific mutant proteins and the pathogenic mechanisms of disease as well as opportunities to test therapeutic interventions.

Transgenic models of neurodegenerative diseases

Identification of genetic mutations linked to familial neurodegenerative diseases have made it possible to generate useful transgenic animal models. Studies using these transgenic animals indicate that many familial neurodegenerative diseases, such as motor neuron disease, Alzheimer's disease, prion diseases and trinucleotide repeat diseases, result from a gain of deleterious properties. The disease-specific pathology in transgenic mice demonstrates the utility of these models in elucidating pathogenic mechanisms of the disease and in developing therapeutic strategies.

The relationships between biophysical activity and the secondary structure of synthetic peptides from the pulmonary surfactant protein SP-B

Synthetic pulmonary surfactants consisting of a mixture of phospholipids with synthetic peptides based on human and bovine surfactant-associated protein SP-B were prepared. These surfactants were analyzed for their biophysical activities by Wilhemly balance experiments and for their secondary structures by circular dichroism (CD) spectroscopy. Four synthetic peptides (SP-1, SP-2, SP-3, and SP-4) combined with the phospholipid mixture displayed significant surfactant properties. The CD spectra showed that the alpha-helical propensities of the peptides in SDS micelles were related to their surfactant activities. These results suggested that the several truncated peptides originated from SP-B protein, when appropriately recombined with phospholipids, could be used as an effective synthetic surfactant for clinical use.

Mechanisms of selective motor neuron death in transgenic mouse models of motor neuron disease

To examine the mechanism(s) of disease underlying ALS, transgenic mouse models have been constructed that express aberrant neurofilaments or mutations in the abundant, cytoplasmic enzyme superoxide dismutase 1 (SOD1). In addition to progressive weakness arising from selective motor neuron death, mice expressing a modest level of a point mutant in neurofilament subunit NF-L show most of the pathologic hallmarks observed in familial and sporadic ALS, including perikaryal proximal axonal swellings, axonal degeneration, and severe skeletal muscle atrophy. Additional mice expressing familial ALS-linked mutations in the cytoplasmic enzyme SOD1, the only proven cause of ALS and which accounts for approximately 20% of familial disease, have demonstrated that at least one mutation causes disease through acquisition of an adverse property by the mutant enzyme, rather than elevation or loss of SOD1 activity. These animals not only provide a detailed look at the pathogenic progression of disease, but also represent a tool for testing hypotheses concerning the specific mechanism(s) of neuronal death and for testing therapeutic strategies.

Heparin neutralization with methylene blue, hexadimethrine, or vancomycin after cardiopulmonary bypass

There are no clinically available alternatives for reversing heparin in protamine-allergic patients. This study examined the ability of methylene blue, hexadimethrine, and vancomycin to reverse circulating heparin so that these compounds can be carefully examined in future placebo-controlled studies in humans. Heparin activity in blood obtained from extracorporeal circuits was reversed by adding protamine (13.5, 27.0, 81.1, 135.1, and 270.3 micrograms/mL), methylene blue (13.5, 27.0, 135.1, 202.7, 270.3, 337.8, 405.4, 473.0, 540.5, and 810.8 micrograms/mL), hexadimethrine (6.8, 13.5, 20.3, 27.0, 81.1, and 135.1 micrograms/mL), or vancomycin (13.5, 27.0, 135.1, 270.3, 540.5, and 810.8 micrograms/mL), and activated clotting times (ACTs) were measured with kaolin (n = 18). Heparinase-ACT was obtained to determine complete reversal. Heparin concentrations were 3.3 +/- 0.3 U/mL with ACT values of 485 +/- 97 s. The ACT at a protamine concentration of 81.1 micrograms/mL and at hexadimethrine concentrations of 81.1 and 135.1 micrograms/mL was not statistically different from heparinase-ACT; however, methylene blue or vancomycin did not reverse the anticoagulation at any concentrations. Hexadimethrine can reverse heparin-induced anticoagulation after cardiopulmonary bypass as well as protamine, although methylene blue or vancomycin did not neutralize heparin in vitro.

Aminopeptidase N purified from gypsy moth brush border membrane vesicles is a specific receptor for Bacillus thuringiensis CryIAc toxin

We have evaluated the binding of Bacillus thuringiensis Cry toxins to aminopeptidase N (APN) purified from Lymantria dispar (gypsy moth) brush border membrane vesicle (BBMV). CryIAc toxin bound strongly to APN, while either the structurally related CryIAa and CryIAb toxins or CryIC, CryIIA, and CryIIIA toxins showed weak binding to APN. An in vitro competition binding study demonstrated that the binding of CryIAc to L. dispar BBMV was inhibited by APN. Inhibition of short circuit current for CryIAc, measured by voltage clamping of whole L. dispar midgut, was substantially reduced by addition of phosphatidylinositol-specific phospholipase C, which is known to release APN from the midgut membrane. In contrast, addition of phosphatidylinositol-specific phospholipase C had only a marginal effect on the inhibition of short circuit current for CryIAa. These data suggest that APN is the major functional receptor for CryIAc in L. dispar BBMV. A ligand blotting experiment demonstrated that CryIAc recognized a 120-kDa peptide (APN), while CryIAa and CryIAb recognized a 210-kDa molecule in L. dispar BBMV. In contrast, CryIAa and CryIAb bound to both the 120- and 210-kDa molecules in Manduca sexta BBMV, while CryIAc recognized only the 120-kDa peptide. The 120-kDa peptide (APN) in L. dispar BBMV reacted with soybean agglutinin, indicating that N-acetylgalactosamine is a component of this glycoprotein.

Heparinase I (neutralase) reversal of systemic anticoagulation

BACKGROUND

Protamine causes multiple adverse reactions. Heparinase I, a specific enzyme that inactivates heparin, is a possible alternative to protamine. In this study, the authors examined the efficacy of heparinase I to reverse heparin-induced anticoagulation in vitro and compared heparinase I to protamine as an antagonist of heparin-induced anticoagulation in dogs.

METHODS

In the in vitro study, blood was obtained from the extracorporeal circuits of 12 patients, and activated clotting times were determined after adding different concentrations of heparinase I. In the in vivo study, 24 anesthetized dogs received 300 units/kg heparin injected intravenously for 5 s, then 10 min later, 3.9 mg/kg protamine, 5-41 micrograms/kg heparinase I, or the vehicle (n = 4/group) were administered intravenously, and activated clotting times and hemodynamics were measured.

RESULTS

In the in vitro study, heparin concentrations of 3.3 +/- 1.0 (mean +/- SD) units/ml (approximately 0.033 mg/ml; n = 12) were reversed in the blood of patients by heparinase I at concentrations > 0.490 microgram/ml. In the canine study, heparinase at all doses studied and protamine effectively reversed the anticoagulating effects of heparin within 10 min of administration. Protamine produced adverse hemodynamic effects, whereas heparinase or its vehicle produced no significant change in arterial pressure.

CONCLUSION

Both heparinase I and protamine effectively reversed heparin anticoagulation. However, as opposed to protamine, heparinase I did not produce any significant hemodynamic changes when given as a bolus to dogs.

Genomic variation of aquatic birnaviruses analyzed with restriction fragment length polymorphisms

Aquatic birnaviruses are the most ubiquitous and diverse group of viruses in the family Birnaviridae. Several cause different diseases in a variety of fish species, such as infectious pancreatic necrosis virus in salmonids in North America, Europe, and Asia and European eel virus in eel in Asia. Most isolates are antigenically related and belong to a single serogroup (serogroup A) comprising nine serotypes. Previous studies with monoclonal antibodies have demonstrated considerable variation in epitope profiles even among strains within a single serotype. The few studies of genomic variation among these viruses, which have focused on the NS/VP3 coding region, demonstrated the existence of several genogroups that generally did not correlate with antigenic groups. In this study, PCR was used to amplify a 1,180-bp cDNA genomic fragment representing most of the VP2 (the major outer capsid protein) coding region from five serotype A type strains and 17 Asian isolates. The PCR products were digested with nine different restriction enzymes. Restriction fragment length polymorphism profiles demonstrated heterogeneity among the tested viruses; however, the isolates from Asia were closely related to each other. Cluster analysis of the restriction fragment length polymorphism patterns demonstrated that these viruses could be divided into four major genogroups. In contrast to previous studies of variation in the NS/VP3 coding region, these genogroups based on variation in the VP2 coding region correlated with a serological classification based on VP2-specific monoclonal antibody reaction patterns. Furthermore, all Asian isolates tested belonged to one genogroup typified by the serotype type strain Ab.

Endoproteolysis of presenilin 1 and accumulation of processed derivatives in vivo

The majority of early-onset cases of familial Alzheimer's disease (FAD) are linked to mutations in two related genes, PS1 and PS2, located on chromosome 14 and 1, respectively. Using two highly specific antibodies against nonoverlapping epitopes of the PS1-encoded polypeptide, termed presenilin 1 (PS1), we document that the preponderant PS1-related species that accumulate in cultured mammalian cells, and in the brains of rodents, primates, and humans are approximately 27-28 kDa N-terminal and approximately 16-17 kDa C-terminal derivatives. Notably, a FAD-linked PS1 variant that lacks exon 9 is not subject to endoproteolytic cleavage. In brains of transgenic mice expressing human PS1, approximately 17 kDa and approximately 27 kDa PS1 derivatives accumulate to saturable levels, and at approximately 1:1 stoichiometry, independent of transgene-derived mRNA. We conclude that PS1 is subject to endoproteolytic processing in vivo.