Characteristics of HLA class I and class II polymorphisms in Rwandan women

OBJECTIVE

To define HLA class I and class II polymorphisms in Rwandans.

METHODS

PCR-based HLA genotyping techniques were used to resolve variants of HLA-A, B, and C to their 2- or 4-digit allelic specificities, and those of DRB1 and DQB1 to their 4- or 5-digit alleles.

RESULTS

Frequencies of 14 A, 8 C, and 14 B specificities and of 13 DRB1 and 8 DQB1 alleles were >/=0.02 in a group of 280 Rwandan women. These major HLA factors produced 6 haplotypes extending across the class I and class II regions: A*01-Cw*04-B* 4501-DRB1*1503-DQB1*0602 (A1-Cw4-B12- DR15 - DQ6), A * 01 - Cw * 04 - B * 4901 -DRB1 * 1302-DQB1*0604 (A1-Cw4-B21-DR13-DQ6), A*30 - Cw*04 - B*15 - DRB1*1101 - DQB1*0301 (A19-Cw4-B15-DR11-DQ7), A*68-Cw*07-B* 4901-DRB1*1302-DQB1*0604(A28-Cw7-B21- DR13 - DQ6), A*30 - Cw*07 - B*5703 - DRB1* 1303-DQB1*0301(A19 - Cw7 - B17 - DR13 - DQ7), and A*74-Cw*07-B*4901-DRB1*1302-DQB1* 0604 (A19-Cw7-B21-DR13-DQ6), respectively. Collectively, these extended haplotypes accounted for about 19% of the total. Other apparent class I-class II haplotypes (e.g., Cw*17-B*42-DRB1*0302-DQB1*0402, Cw*06- B*58-DRB1*1102-DQB1*0301, and Cw*03- B*15-DRB1*03011-DQB1*0201) did not extend to the telomeric HLA-A locus, and other 3-locus class I haplotypes (e.g., A*68-Cw*04-B*15, A*74-Cw*04-B*15, and A*23-Cw*07-B*4901) completely or partially failed to link with any specific class II alleles.

DISCUSSION

Frequent recombinations appeared to occur between the three evolutionarily conserved HLA blocks carrying the class I and class II loci. The HLA class I profile seen in Rwandans was not directly comparable with those known in the literature, although the class II profile appeared to resemble those in several African populations. These data provide additional evidence for the extensive genetic diversity in Africans.

Genotyping TAP2 variants in North American Caucasians, Brazilians, and Africans

The protein forms of transporter associated with antigen processing, subunit 2 (TAP2), differ either by amino acid substitutions (Thr374Ala, Ile379Val, Ile467Val, Thr565Ala, Val577Met, Cys651Arg, and Ala665Thr) or by a truncation (Gln687Stop) of 17 amino acid residues at the C-terminus. Nonsynonymous single nucleotide polymorphisms (N-SNPs) causing these amino acid variations except 577Val were detected in genomic DNA samples from North American Caucasians (n = 76), Brazilians (n = 148), Rwandans (n = 285), and Zambians (n = 117). Exclusive (100%) and nearly exclusive (>95%) linkage disequilibrium was seen with a number of N-SNPs. The average heterozygosity at any given dimorphic site ranged from 7.3% to 44.6%, and at least four N-SNPs showed clear population specificity. N-SNP combinations alone led to the identification of 16 relatively common alleles, which appeared to form at least three lineages. Further analyses of 101 cDNA samples from Brazilians detected nine expressed TAP2 alleles, four of which matched the official assignments. Genetic complexity at the TAP2 locus was further enhanced by two out of five synonymous SNPs (S-SNPs), especially the GGT386GGG (Gly) that had similar heterozygosity rates in Caucasians (28.9%), Rwandans (33.3%), and Zambians (33.3%). Overall, distribution of both synonymous and nonsynonymous SNPs in the various ethnic groups examined here conformed well to the Hardy-Weinberg equilibrium, and between 57.9% and 77.0% of subjects in each ethnic group were heterozygous with two TAP2 alleles predicted to differ by at least one amino acid residue. Such complexity of TAP2 polymorphisms, in the form of SNPs as well as alleles, is likely to complicate the analyses of disease associations and haplotype structures in the HLA class II region.

Inappropriate shock therapy in a heart failure defibrillator

A 63-year-old male with dilated cardiomyopathy underwent implantation of a "heart failure" defibrillator capable of biventricular pacing. He received an inappropriate shock 5 hours after the procedure. Stored electrograms revealed that during each sinus beat the ventricular channel recorded up to three separate events. These resulted from far-field atrial sensing by the coronary venous lead, appropriate right ventricular sensing, then delayed left ventricular sensing (the result of left bundle branch block). As a consequence of far-field left atrial sensing the two subsequent ventricular electrograms fell within the VF zone. Following an atrial premature beat, VF detection criteria were satisfied and shock therapy delivered. Although coronary venous lead repositioning eliminated far-field atrial sensing, double counting of the widely split right and left ventricular electrograms still occurred during sinus rhythm. Shortening the programmed AV delay resulted in constant biventricular pacing with a single electrogram.

Near full-length clones and reference sequences for subtype C isolates of HIV type 1 from three different continents

Among the major circulating HIV-1 subtypes, subtype C is the most prevalent. To generate full-length subtype C clones and sequences, we selected 13 primary (PBMC-derived) isolates from Zambia, India, Tanzania, South Africa, Brazil, and China, which were identified as subtype C by partial sequence analysis. Near full-length viral genomes were amplified by using a long PCR technique, sequenced in their entirety, and phylogenetically analyzed. Amino acid sequence analysis revealed 10.2, 6.3, and 17.3% diversity in predicted Gag, Pol, and Env protein sequences. Ten of 13 viruses were nonmosaic subtype C genomes, while all three isolates from China represented B/C recombinants. One of them was composed primarily of subtype C sequences with three small subtype B portions in gag, pol, and nef genes. Two others exhibited these same mosaic regions, but contained two additional subtype B portions at the gag/pol overlap and in the accessory gene region, suggesting ongoing B/C recombination in China. All subtype C genomes contained a prematurely truncated second exon of rev, but other previously proposed subtype C signatures, including three potential NF-kappa B-binding sites in the viral promoter-enhancer regions, were found in only a subset of these genomes.

Endoplasmic reticulum retention and prolonged association of a von Willebrand's disease-causing von Willebrand factor variant with ERp57 and calnexin

We have previously identified a mutation (R273W) in the von Willebrand factor (VWF) propeptide that results in quantitative deficiency of plasma VWF and a loss of high molecular weight VWF multimers. Recombinant VWF having the R273W mutation (rVWFR273W) expressed in COS-7 cells demonstrated severely impaired secretion and degradation in an intracellular location [Allen, S., et al. (2000) Blood 96, 560-568]. In this report we used pulse-chase analysis and endoglycosidase H digestion of wild-type rVWF and rVWFR273W immunoprecipitated from COS-7 cells to show that rVWFR273W was retained in the endoplasmic reticulum (ER). We demonstrate for the first time that wild-type rVWF and rVWFR273W interacted with the thiol-dependent oxidoreductase ERp57 during biosynthesis in the ER. Pulse chase analysis demonstrated that the interactions of rVWFR273W with ERp57 and calnexin were prolonged compared to wild-type rVWF. In contrast there was no apparent difference between rVWFR273W and wild-type rVWF in their time-courses of interaction with calreticulin.

The benefit of geriatric intervention in surgery-increased throughput does not necessarily need more beds

OBJECTIVE

Three years ago a consultant geriatrician began regular visits to the coloproctology and general surgery wards of an acute Trust every weekday, to assist staff with the medical management, rehabilitation and discharge planning of patients aged 65 years and above. The length of stay of these patients in the first 10 months of the appointment was compared with younger concurrent controls and with historical controls in the preceding 10 months.

RESULTS

The mean length of stay for the 4146 patients aged 16 years and above in a 10-month intervention period was 1.3 days shorter (95% confidence interval (CI) 0.86-1.74 days) than for the 4002 patients in the 10-month control period. This pattern was consistent across all ages and types of surgery, including major colorectal resection.

CONCLUSION

There was an important benefit to the availability of coloproctology and general surgical beds in this acute Trust. More efficient rehabilitation of elderly patients reduces 'bed blockage' post-operatively, and allows more effective use of available resources. Co-ordination of the geriatric service with the specialized stoma support service allows earlier discharge of the elderly, and their relocation to appropriate premises where long-term changes in bowel habit and problems with stoma care can be managed away from the acute surgical unit.

Rapid voluntary testing and counseling for HIV. Acceptability and feasibility in Zambian antenatal care clinics

Voluntary testing and counseling (VTC) for HIV/AIDS is now widely accepted as an effective HIV prevention and control strategy among heterosexual couples in sub-Saharan Africa. The most appropriate format and venue for VTC remains a topic of debate among clinicians and public health professionals. Our research done in Lusaka, Zambia, took a tripartite approach to exploring the most acceptable format and venue for VTC: a community survey of attitudes towards VTC, a pre- and postcounseling knowledge survey, and a pilot study of same-day VTC in urban antenatal care clinics. A community survey of 181 individuals was conducted in July-August 1996 based on a structured questionnaire. A pre- and post-VTC intervention knowledge survey was conducted during the same period among 82 couples attending the Zambia-UAB HIV Research Project (ZUHRP) HIV VTC center in Lusaka. Finally, same-day HIV VTC was pilot tested in six antenatal clinic locations during February-May 1997 and June-August 1998. The community survey revealed that 98% of participants support promotion of HIV VTC in the community and 83.8% prefer the same-day testing format. The knowledge survey revealed misconceptions about discordance within a couple and perinatal transmission of HIV. Pilot testing in antenatal clinics was well received, with 84% of pregnant women requesting testing and 25% having positive HIV serologies. Women with primary school or less education, those seeking antenatal care in local clinics, and those seen before the third trimester of pregnancy were more likely to request HIV testing. Testing and counseling for HIV were shown to be feasible and effective in the antenatal clinic setting. Implementation of same-day HIV VTC in antenatal clinics is an effective strategy to prevent vertical transmission and should be expanded to include couples to leverage a decrease in heterosexual transmission as well.

Ascorbate levels in red blood cells and urine in patients with sickle cell anemia

Ascorbic acid can be important in sickle cell anemia (SCA) because significant oxidative stress occurs in the disease. Ascorbate could contribute to reduction of the increased oxygen free radicals generated in sickle red blood cells (SRBC) and to the recycling of vitamin E in the cells, while renal loss could contribute to the low plasma levels. Evaluation of red blood cell (RBC) and urine ascorbate in SCA has not been reported. Results showed (1) ascorbate levels in SRBC were similar to those in normals; (2) urine ascorbate excretion was increased in 36% of patients; (3) plasma levels of ascorbate were decreased.

CONCLUSIONS

(1) Ascorbate is present in SRBC, most likely due to ascorbate recycling, despite increased free-radical generation. (2) The increase in renal excretion may contribute to the low plasma levels of ascorbate. (3) The presence of ample ascorbate in SRBC and decreased plasma ascorbate suggests that ascorbate movement across the SRBC membrane may differ from normal RBC.

A multifilamented electrode in the middle cardiac vein reduces energy requirements for defibrillation in the pig

OBJECTIVE

To compare the defibrillation efficacy of a novel lead system placed in the middle cardiac vein with a conventional non-thoracotomy lead system.

METHODS

In eight pigs (weighing 35-71 kg), an electrode was advanced transvenously to the right ventricular apex (RV), with the proximal electrode in the superior caval vein (SCV). Middle cardiac vein (MCV) angiography was used to delineate the anatomy before a three electrode system (length 2 x 25 mm + 1 x 50 mm) was positioned in the vein. An active housing (AH) electrode was implanted in the left pectoral region. Ventricular fibrillation was induced and biphasic shocks were delivered by an external defibrillator. The defibrillation threshold was measured and the electrode configurations randomised to: RV-->AH, RV+MCV-->AH, MCV-->AH, and RV-->SCV+AH.

RESULTS

For these configurations, mean (SD) defibrillation thresholds were 27.3 (9.6) J, 11.9 (2.9) J, 15.2 (4.3) J, and 21.8 (9.3) J, respectively. Both electrode configurations incorporating the MCV had defibrillation thresholds that were significantly less than those observed with the RV-->AH (p < 0.001) and RV-->SCV+AH (p < 0.05) configurations. Necropsy dissection showed that the MCV drained into the coronary sinus at a location close to its orifice (mean distance = 2.7 (2.2) mm). The MCV bifurcated into two main branches that drained the right and left ventricles, the left branch being the dominant vessel in the majority (6/7) of cases.

CONCLUSIONS

Placement of specialised defibrillation electrodes within the middle cardiac vein provides more effective defibrillation than a conventional tight ventricular lead.

Hydrothermal synthesis of (C6N2H14)2(UVI2UIVO4F12), a mixed-valent one-dimensional uranium oxyfluoride

A new hybrid organic-inorganic mixed-valent uranium oxyfluoride, (C6N2H14)2(U3O4F12), UFO-17, has been synthesized under hydrothermal conditions using uranium dioxide as the uranium source, hydrofluoric acid as mineralizer, and 1,4-diazabicyclo[2.2.2]octane as template. The single-crystal X-ray structure was determined. Crystals of UFO-17 belonged to the orthorhombic space group Cmcm (no. 63), with a = 14.2660(15) A, b = 24.5130(10) A, c = 7.201(2) A, and Z = 4. The structure reveals parallel uranium-containing chains of two types: one type is composed of edge-sharing UO2F5 units; the other has a backbone of edge-sharing UF8 units, each sharing an edge with a pendant UO2F5 unit. Bond-valence calculations suggest the UF8 groups contain UIV, while the UO2F5 groups contain UVI. EXAFS data give results consistent with the single-crystal X-ray structure determination, while comparison of the uranium LIII-edge XANES of UFO-17 with that of related UIV and UVI compounds supports the oxidation-state assignment. Variable-temperature magnetic susceptibility measurements on UFO-17 and a range of related hybrid organic-inorganic uranium(IV) and uranium(VI) fluorides and oxyfluorides further support the formulation of UFO-17 as a mixed-valent UIV/UVI compound.

Increased AKT activity contributes to prostate cancer progression by dramatically accelerating prostate tumor growth and diminishing p27Kip1 expression

The PTEN tumor suppressor gene is frequently inactivated in human prostate cancers, particularly in more advanced cancers, suggesting that the AKT/protein kinase B (PKB) kinase, which is negatively regulated by PTEN, may be involved in human prostate cancer progression. We now show that AKT activation and activity are markedly increased in androgen-independent, prostate-specific antigen-positive prostate cancer cells (LNAI cells) established from xenograft tumors of the androgen-dependent LNCaP cell line. These LNAI cells show increased expression of integrin-linked kinase, which is putatively responsible for AKT activation/Ser-473 phosphorylation, as well as for increased phosphorylation of the AKT target protein, BAD. Furthermore, expression of the p27(Kip1) cell cycle regulator was diminished in LNAI cells, consistent with the notion that AKT directly inhibits AFX/Forkhead-mediated transcription of p27(Kip1). To assess directly the impact of increased AKT activity on prostate cancer progression, an activated hAKT1 mutant was overexpressed in LNCaP cells, resulting in a 6-fold increase in xenograft tumor growth. Like LNAI cells, these transfectants showed dramatically reduced p27(Kip1) expression. Together, these data implicate increased AKT activity in prostate tumor progression and androgen independence and suggest that diminished p27(Kip1) expression, which has been repeatedly associated with prostate cancer progression, may be a consequence of increased AKT activity.

Reduction in defibrillation threshold using an auxiliary shock delivered in the middle cardiac vein

Defibrillation in the middle cardiac vein (MCV) has been shown to reduce ventricular defibrillation thresholds (DFTs). Low amplitude auxiliary shock (AS) from an electrode sutured to the left ventricle at thoracotomy have also been shown to reduce DFT if delivered immediately prior to a biphasic shock (between the ventricular RV and superior vena caval (SVC) electrodes). This study investigates the impact on DFT of an AS shock from a transvenously placed MCV lead system. A standard defibrillation electrode was positioned in the RV in eight anesthetized pigs (35-43 kg). A 50 x 1.8-mm electrode was inserted in the MCV through an 8 Fr angioplasty guide catheter. A 150-V (leading edge) monophasic AS was delivered (95 microF capacitor) from the MCV-->Can with three different pulse widths (3, 5, 7 ms). A primary biphasic shock (PS) (95 microF capacitor, phase 1: 44% tilt, 1.6-ms extension and phase 2: 2.5-ms fixed duration) was delivered from the RV-->Can +/- AS. The four configurations were randomized and DFTs (PS + AS) assessed using a modified binary search. Ventricular fibrillation (VF) was induced with 60 Hz AC followed 10 seconds later by the test shock. The DFTs were compared using repeated measures analysis of variance (ANOVA). All configurations incorporating AS produced significant (P < 0.05) reduction in the DFT compared to no AS (13.8 +/- 7.4 J). There was no difference in the efficacy of differing pulse widths (P > 0.05); 3 ms (11.0 +/- 5.4 J), 5 ms (11.5 +/- 6.0), and 7 ms (10.6 +/- 5.3 J). In conclusion, delivering an AS from a transvenous lead system deployed in the MCV reduces the DFT by 23% compared to a conventional RV-->Can shock alone.

A novel von Willebrand disease-causing mutation (Arg273Trp) in the von Willebrand factor propeptide that results in defective multimerization and secretion

In this report we describe the molecular defect underlying partial and severe quantitative von Willebrand factor (VWF) deficiencies in 3 families previously diagnosed with types 1 and 3 Von Willebrand-disease. Analysis of the VWF gene in affected family members revealed a novel C to T transition at nucleotide 1067 of the VWF complemetary DNA (cDNA), predicting substitution of arginine by tryptophan at amino acid position 273 (R273W) of pre-pro-VWF. Two patients, homozygous for the R273W mutation, had a partial VWF deficiency (VWF:Ag levels of 0.06 IU/mL and 0.09 IU/mL) and lacked high-molecular weight VWF multimers in plasma. A third patient, also homozygous for the R273W mutation, had a severe VWF deficiency (VWF:Ag level of less than 0.01 IU/mL) and undetectable VWF multimers in plasma. Recombinant VWF having the R273W mutation was expressed in COS-7 cells. Pulse-chase experiments showed that secretion of rVWFR273W was severely impaired compared with wild-type rVWF. However, the mutation did not affect the ability of VWF to form dimers in the endoplasmic reticulum (ER). Multimer analysis showed that rVWFR273W failed to form high-molecular-weight multimers present in wild-type rVWF. We concluded that the R273W mutation is responsible for the quantitative VWF deficiencies and aberrant multimer patterns observed in the affected family members. To identify factors that may function in the intracellular retention of rVWFR273W, we investigated the interactions of VWF expressed in COS-7 cells with molecular chaperones of the ER. The R273W mutation did not affect the ability of VWF to bind to BiP, Grp94, ERp72, calnexin, and calreticulin in COS-7 cells. (Blood. 2000;96:560-568)

Involvement of luminal bacteria, heat shock protein 60, macrophages and gammadelta T cells in dextran sulfate sodium-induced colitis in rats

The in vivo immunological events in dextran sulfate sodium (DSS) -induced colitis were evaluated. Rats were fed water (control) or 5% DSS. Colonic sections were assessed by light microscopy, Gram stain, immunohistochemistry, and electron microscopy. A progressive decline in number and increase in fragmentation of bacteria in the colonic lumen was observed over time. Luminal bacteria were the first to show heat shock protein 60 (HSP60) staining (day 3). Macrophages in close proximity to these bacteria were next to show such staining (day 6), and finally the damaged epithelial cells when colitis became severe (day 15). Ultrastructural assessment showed cell-cell contact interactions between macrophages and dendritic gammadelta T cells. An increase in the number of gammadelta T cells and ED1-positive macrophages in the affected colonic tissue over time was documented. These results suggest colonic bacteria, host macrophages, and gammadelta T cells play specific roles in the immunological reactions in DSS-induced colitis, possibly via an HSP60-mediated mechanism.

The role of ERp57 in disulfide bond formation during the assembly of major histocompatibility complex class I in a synchronized semipermeabilized cell translation system

We have established a semipermeabilized cell system that reproduces the folding and assembly of a major histocompatibility complex (MHC) class I complex as it would occur in the intact cell. The translation of the MHC class I heavy chain (HLA-B27) in this system was synchronized allowing the folding and assembly of polypeptide chains synthesized within a short time frame to be analyzed. This has enabled us to dissect the time course of interaction of both disulfide and nondisulfide-bonded heavy chain with various molecular chaperones during its assembly in a functionally intact endoplasmic reticulum. The results demonstrate that unassembled, nondisulfide-bonded forms of heavy chain interact initially with calnexin. A later and more prolonged interaction of calreticulin, specifically with assembled, disulfide-bonded heavy chain, highlights distinct differences in the roles of these two proteins in the assembly of MHC class I molecules. We also demonstrate that the thiol-dependent reductase ERp57 initially interacts with nondisulfide-bonded heavy chain, but this rapidly becomes disulfide-bonded and indicates that heavy chain folding occurs during its interaction with ERp57. In addition, we also confirm a direct interaction between MHC class I heavy chain and tapasin, emphasizing the role that this protein plays in the later stages of MHC class I assembly.

Characterization of the surfaces generated by liposome binding to the modified dextran matrix of a surface plasmon resonance sensor chip

The dextran matrix of a surface plasmon resonance (SPR) sensor chip modified with hydrophobic residues (BIAcore sensor chip L1) provides an ideal substrate for liposome adsorption. Liposomes of different lipid compositions are captured on the sensor chips by inserting these residues into the liposome membrane, thereby generating stable lipid surfaces. To gain a more detailed understanding of these surfaces, and to prove whether the liposomes stay on the matrix as single particles or form a continuous lipid layer by liposome fusion, we have investigated these materials, using atomic force microscopy (AFM) and fluorescence microscopy. Force measurements with AFM probes functionalized with bovine serum albumin (BSA) were employed to recognize liposome adsorption. Analysis of the maximal adhesive force and adhesion energy reveals a stronger interaction between BSA and the dextran matrix compared to the lipid-covered surfaces. Images generated using BSA-coated AFM tips indicated a complete and homogeneous coverage of the surface by phospholipid. Single liposomes could not be detected even at lower lipid concentrations, indicating that the liposomes fuse and form a lipid bilayer on the dextran matrix. Experiments with fluorescently labeled liposomes concurred with the AFM studies. Surfaces incubated with liposomes loaded with TRITC-labeled dextran showed no fluorescence, indicating a complete release of the encapsulated dye. In contrast, surfaces incubated with liposomes containing a fluorescently labeled lipid showed fluorescence.

Treatment of spit tobacco users with transdermal nicotine system and mint snuff

The purpose of this study was to examine the effects of nicotine patch and mint snuff (a nonnicotine product) on craving, withdrawal symptoms, and treatment outcome. This study involved a 2 x 2 factorial design, with Active Nicotine Versus Placebo Patch as one of the factors and Mint Snuff Versus No Mint Snuff as the other factor. Spit tobacco users (N = 402, n = 100-101 in each condition) were randomly assigned to 1 of the 4 treatment conditions for a period of 10 weeks. Treatment outcome was measured up to 62 weeks. The results showed that the nicotine patch was effective in increasing short-term abstinence over the placebo patch and in reducing craving and withdrawal signs and symptoms from spit tobacco. Although mint snuff was not effective in enhancing treatment outcome, it reduced craving and withdrawal symptoms. No interaction effects were observed. At this time, the use of the nicotine patch and mint snuff should be primarily considered for the reduction of craving and withdrawal symptoms.

Increased defibrillation threshold with right-sided active pectoral can

The aim of this study was to identify the optimal position on the chest wall to place an implant able cardioverter defibrillator in a two-electrode system, consisting of a right ventricular electrode and active can.

METHODS AND RESULTS

Defibrillation thresholds (DFT) were measured in 10 anaesthetised pigs (weight 33-45 kg). An Angeflextrade mark lead was introduced transvenously to the right ventricular apex. The test-can (43 cc) was implanted submuscularly in each of four locations: left pectoral (LP), right pectoral (RP), left lateral (LL) and apex (A). The sequence in which the four locations were tested was randomized. Ventricular fibrillation (VF) was induced using 60 Hz alternating current. Rectangular biphasic shocks were delivered 10 seconds after VF induction. The DFT was measured using a modified four-reversal binary search. The results of the four configurations were: LP, 14.6+/- 4.0 J; RP, 18.8+/- 4.2 J; LL, 14.7+/- 4.1 J; A, 14.9+/- 3.1 J. Repeated measures analysis of variance showed that the DFT of RP was significantly higher than LP, LL and A (p < 0.05).

CONCLUSIONS

Implanting an active can in the RP position increases the DFT by 29% compared to LP, LL and A sites. The can position on the left thorax does not appear to have a significant influence on DFT.

Two novel type 2N von Willebrand disease-causing mutations that result in defective factor VIII binding, multimerization, and secretion of von Willebrand factor

Two novel mutations, a T-to-C transition at nucleotide 2612 and a T-to-G transversion at nucleotide 3923 of the von Willebrand factor (vWF) complementary DNA, were detected by analysis of the vWF gene in DNA from members of 2 families with atypical von Willebrand disease. The T2612C transition predicts substitution of cysteine by arginine at amino acid position 788 (C788R), and the T3923G transversion predicts substitution of cysteine by glycine at position 1225 (C1225G) of pre-pro-vWF. The patients homozygous for the C788R and C1225G mutations both had a partial vWF deficiency (0. 18 IU/mL and 0.07 IU/mL vWF antigen, respectively); vWF in plasma from patients homozygous for either the C788R or the C1225G mutation failed to bind factor VIII and lacked high molecular weight multimers. Recombinant (r) vWF molecules having the C788R or C1225G mutation were expressed in COS-7 cells. Both rvWF C788R and rvWF C1225G exhibited significantly impaired secretion and failed to bind factor VIII. Recombinant vWF C788R in COS-7 culture medium showed a severe reduction in high molecular weight multimers, whereas rvWF C1225G showed a very mild reduction in high molecular weight multimers when compared with wild-type rvWF. (Blood. 2000;95:2000-2007)

Cloning and expression of the Wnt antagonists Sfrp-2 and Frzb during chick development

The Wnt genes are known to play fundamental roles during patterning and development of a number of embryonic structures. Receptors for Wnts are members of the Frizzled family of proteins containing a cysteine-rich domain (CRD) that binds the Wnt protein. Recently several secreted frizzled-related proteins (Sfrps) that also contain a CRD have been identified and some of these can both bind and antagonise Wnt proteins. In this paper we report the expression patterns of the chick homologues of Frzb, a known Wnt antagonist, and Sfrp-2. Both genes are expressed in areas where Wnts are known to play a role in development, including the neural tube, myotome, cartilage, and sites of epithelial-mesenchymal interactions. Initially, Sfrp-2 and Frzb are expressed in overlapping areas in the neural plate and neural tube, whereas later, they have distinct patterns. In particular Sfrp-2 is associated with myogenesis while Frzb is associated with chondrogenesis, suggesting that they play different roles during development. Finally, we have used the early Xenopus embryo as an in vivo assay to show that Sfrp-2, like Frzb, is a Wnt antagonist. These results suggest that Sfrp-2 and Frzb may function in the developing embryo by modulating Wnt signalling.

Knowledge of human papillomavirus infection among young adult men and women: implications for health education and research

Human papillomavirus (HPV) infection of the genital tract is one of the most common sexually transmitted diseases (STDs), and a subset of genital tract HPVs are etiologically associated with cervical cancer. The prevalence of HPV infection is highest among adolescents and young adults. This study was undertaken to explore first year college students' knowledge about HPVs and to determine whether there were gender differences in this knowledge. An anonymous survey was distributed to all first year students at a private university. The results were analyzed by gender. We found that 96.2% of males and 95.4% of females had heard of genital warts, although only 4.2% of males and 11.6% of females knew that HPV caused genital warts. Although there was a greater awareness of genital warts than HPV in this population, students were uncertain about modes of transmission of both genital warts and HPVs, and unclear about the importance of HPV infection relative to other STDs. For both men and women (87% and 87.4%, respectively), health education classes were the major source of information about STDs. We conclude that health education should be reconceptualized to incorporate a better understanding of STDs, including HPV infection, by engaging adolescents and young adults in exploring the biological and social context of STDs, their public health importance, strategies for prevention, and the uncertainty of our scientific knowledge.