The prevalence of immunization to Duffy antigens in a population of known racial distribution

A retrospective study at our hospital determined the race or ethnicity of patients seen in an 8-year period who had formed antibodies to Duffy antigens. During that time, 9876 serologic investigations had been performed as a result of a positive direct or indirect antiglobulin test. Among these samples, sera from 45 previously transfused or pregnant patients contained anti-Fya and two contained anti-Fy3. Twenty-nine of the sera that contained anti-Fya (62%) were from blacks, 12 (25%) were from whites, and 6 (13%) were from Hispanics. Both examples of anti-Fy3 were made by black patients. Red cells (RBCs) from 21 of the black patients were Fy(a-b-), those from 7 were Fy(a-b+), and those from 1 could not be phenotyped. RBCs from 17 of the non-black patients were Fy(a-b+) and those from 1 could not be phenotyped. The population of transfused patients evaluated in this study was 47 percent black, 29 percent white, and 24 percent Hispanic. Calculations based on an expected Fy(a-) frequency of 88 percent in blacks, 33 percent in whites, and 20 percent in Hispanics predict that the racial makeup of the Fy(a-) population at our hospital would be 73 percent black, 18 percent white, and 9 percent Hispanic, which is not significantly different (p = 0.25) from the racial makeup of the patients forming anti-Fya and -Fy3. These data indicate that blacks make antibodies to Duffy antigens as frequently as non-blacks.     

Maternal Temperature Elevation and Occiput Posterior Position at Birth Among Low‐Risk Women Receiving Epidural Analgesia

Introduction: To evaluate the relationship between maternal temperature elevation and occiput posterior position at birth as well as the association of fetal head position and temperature elevation on method of birth among women receiving epidural analgesia. Methods: We conducted a secondary analysis of data from the Fetal Orientation during Childbirth by Ultrasound Study (FOCUS), which used serial ultrasounds to evaluate the effect of epidural anesthesia on fetal position at birth in low‐risk women. The current analysis was limited to the 1428 study participants who received epidural analgesia. Results: In our population, 47% (n = 669) of women had a maximum intrapartum temperature greater than or equal to 99.6°F (37.6°C). The prevalence of fetal occiput posterior position at admission did not differ between women who later developed temperature elevations (24.4%) and those who did not (23.6%, P= .70). Women who developed an elevated temperature greater than or equal to 99.6°F (37.6°C) had an increased risk of occiput posterior fetal head position at birth regardless of the amount of temperature elevation (odds ratio [OR]= 2.0; 95% confidence interval [CI], 1.5‐2.8); the association persisted after control for potentially confounding factors (adjusted OR = 1.5; 95% CI, 1.1‐2.1). The cesarean birth rate among women with both temperature elevation and occiput posterior position at birth was more than 12 times the rate of women with neither risk factor (adjusted OR = 12.6; 95% CI, 7.5‐21.2). Discussion: Intrapartum temperature elevation among women receiving epidural analgesia, even if only to 99.6°F (37.6°C), is associated with approximately a 2‐fold increase in the occurrence of occiput posterior fetal head position at birth. Additionally, although this observational study cannot establish causal links, our findings suggest that the relationship between epidural‐related intrapartum temperature elevation and occiput posterior position at birth could contribute to an increased cesarean birth rate among women receiving epidural analgesia for pain relief in labor.     

Twenty-year experience with the St Jude Medical mechanical valve prosthesis

BACKGROUND: We have prospectively followed all adult St Jude Medical mechanical valve recipients at the Medical University of South Carolina since the initial implant in January 1979 and now present our 20-year experience. METHODS: We prospectively followed 837 valve recipients (aortic valve replacement; n = 478; mitral valve replacement; n = 359) from January 1979 to December 2000 at 12-month intervals. RESULTS: Ages ranged from 19 to 84 years. Follow-up averaged (mean +/- standard deviation) 7 +/- 5 years (98% complete). Patients were in New York Heart Association class III or IV in 77% (aortic valve replacement) and 89% (mitral valve replacement) preoperatively. A 19-mm valve was implanted in 15.5% of aortic valve replacement patients. Coronary bypass was required in 31% of aortic valve replacements and 20% of mitral valve replacements. Operative mortality was 17/478 (3.6%) in aortic valve replacement and 19/359 (5.3%) in mitral valve replacement, and multivariable predictors were 19-mm valve size, 3 or more coronary bypass grafts, and New York Heart Association class IV for aortic valve replacement and New York Heart Association class IV and age for mitral valve replacement. Actuarial survivorship at 10 and 20 years was 57% +/- 3% and 26% +/- 5% for aortic valve replacement and 61% +/- 3% and 39% +/- 4% for mitral valve replacement. Multivariable predictors of late death were African-American ethnicity, New York Heart Association class III or IV, coronary bypass, and age for aortic valve replacement and New York Heart Association class III or IV, coronary bypass, and age for mitral valve replacement. For aortic valve replacement, effective orifice area was univariately (P =.002) but not multivariately (P =.378) predictive of late death. Structural valve deterioration was not observed. For aortic valve replacement, actuarial freedom (at 10 and 20 years) from reoperation was 93% +/- 1% and 90% +/- 2%; thromboembolism, 82% +/- 3% and 68% +/- 8%; bleeding events, 77% +/- 3% and 66% +/- 6%; prosthetic valve endocarditis, 94% +/- 1% and 94% +/- 1%; valve-related mortality, 94% +/- 2% and 86% +/- 4%; and valve-related mortality or morbidity, 58% +/- 3% and 32% +/- 8%. For mitral valve replacement, actuarial freedom (at 10 and 20 years) from reoperation was 96% +/- 1% and 90% +/- 3%; thromboembolism, 77% +/- 3% and 59% +/- 7%; bleeding events, 86% +/- 2% and 65% +/- 8%; prosthetic valve endocarditis, 98% +/- 1% and 96% +/- 2%; valve-related mortality, 89% +/- 0.2% and 74% +/- 8%; and valve-related mortality or morbidity, 63% +/- 3% and 29% +/- 7%. CONCLUSIONS: After 2 decades of observation with close follow-up, the St Jude Medical mechanical valve continues to be a reliable prosthesis.     

Structure of sugar-bound LacY

Here we describe the X-ray crystal structure of a double-Trp mutant (Gly46→Trp/Gly262→Trp) of the lactose permease of Escherichia coli (LacY) with a bound, high-affinity lactose analog. Although thought to be arrested in an open-outward conformation, the structure is almost occluded and is partially open to the periplasmic side; the cytoplasmic side is tightly sealed. Surprisingly, the opening on the periplasmic side is sufficiently narrow that sugar cannot get in or out of the binding site. Clearly defined density for a bound sugar is observed at the apex of the almost occluded cavity in the middle of the protein, and the side chains shown to ligate the galactopyranoside strongly confirm more than two decades of biochemical and spectroscopic findings. Comparison of the current structure with a previous structure of LacY with a covalently bound inactivator suggests that the galactopyranoside must be fully ligated to induce an occluded conformation. We conclude that protonated LacY binds d-galactopyranosides specifically, inducing an occluded state that can open to either side of the membrane.The lactose permease of Escherichia coli (LacY), a paradigm for the major facilitator superfamily (MFS), binds and catalyzes transport of d-galactose and d-galactopyranosides specifically with an H⁺ (1, 2). In contrast, LacY does not recognize d-glucose or d-glucopyranosides, which differ only in the orientation of the C4-OH of the pyranosyl ring. By using the free energy released from the energetically downhill movement of H⁺ in response to the electrochemical H⁺ gradient (), LacY catalyzes the uphill (active) transport of galactosides against a concentration gradient. Because coupling between sugar and H⁺ translocation is obligatory, in the absence of , LacY also can transduce the energy released from the downhill transport of sugar to drive uphill H⁺ transport with the generation of , the polarity of which depends upon the direction of the sugar gradient.It also has been shown that LacY binds sugar with a pK_a of ∼10.5 and that sugar binding does not induce a change in ambient pH; both findings indicate that the protein is protonated over the physiological range of pH (3–5). These observations and many others (1, 2) provide evidence for an ordered kinetic mechanism in which protonation precedes galactoside binding on one side of the membrane and follows sugar dissociation on the other side. Recent considerations (6) suggest that a similar ordered mechanism may be common to other members of the MFS.Because equilibrium exchange and counterflow are unaffected by imposition of , it is apparent that the alternating accessibility of sugar- and H⁺-binding sites to either side of the membrane is the result of sugar binding and dissociation and not of (reviewed in refs. 1 and 2). Moreover, downhill lactose/H⁺ symport from a high to a low lactose concentration exhibits a primary deuterium isotope effect that is not observed for -driven lactose/H⁺ symport, equilibrium exchange, or counterflow (7, 8). Thus, it is likely that the rate-limiting step for downhill symport is deprotonation (9, 10), whereas in the presence of either dissociation of sugar or a conformational change leading to deprotonation is rate-limiting.X-ray crystal structures of WT LacY (11), the conformationally restricted mutant C154G (12, 13), and a single-Cys mutant with covalently bound methanethiosulfonyl-galactopyranoside (MTS-Gal) (14) have been determined in an inward-facing conformation. The structures consist of two six-helix bundles that are related by a quasi twofold symmetry axis in the membrane plane, linked by a long cytoplasmic loop between helices VI and VII. Furthermore, in each six-helix bundle, there are two three-helix bundles with inverted symmetry (6, 15). The two six-helix bundles surround a deep hydrophilic cavity tightly sealed on the periplasmic face and open only to the cytoplasmic side (an inward-open conformation). Although crystal structures reflect only a single lowest-energy conformation under conditions of crystallization, the entire backbone appears to be accessible to water (16–18), and an abundance of biochemical and spectroscopic data (19–27) demonstrate that sugar binding causes the molecule to open alternatively to either side of the membrane, thereby providing strong evidence for an alternating-access model (reviewed in refs. 28 and 29).The initial X-ray structure of conformationally restricted C154G LacY was obtained with density at the apex of the central cavity, but because of limited resolution, the identity of the bound sugar at this site and/or side-chain interactions are difficult to specify with certainty. However, biochemical and spectroscopic studies show that LacY contains a single galactoside-binding site and that the residues involved in sugar binding are located at or near the apex of the central cavity. Although the specificity of LacY is strongly directed toward the C4-OH of the galactopyranosyl ring, other OH groups also are important in the following order: C4-OH >> C6-OH > C3-OH > C2-OH (30, 31). Cys-scanning mutagenesis, site-directed alkylation, and direct binding assays show that Glu126 (helix IV) and Arg144 (helix V) are irreplaceable for substrate binding and probably are charge-paired (4, 32–35). Trp151 (helix V), two turns removed from Arg144, stacks aromatically with the galactopyranosyl ring (36, 37). Glu269 (helix VIII), another irreplaceable residue (38–40), also is essential for sugar recognition and binding and cannot be replaced even with Asp without markedly decreasing affinity (4, 41). It has been shown recently (42) that Asn272 (helix VIII) also is essential for binding and transport. In contrast, Cys148 (helix V), which is protected from alkylation by substrate, and Ala122 (helix IV), where bulky replacements make LacY specific for galactose, are close to the binding site but probably do not contact the sugar directly.Among the conserved residues in LacY and other MFS members are two Gly–Gly pairs between the N- and C-terminal six-helix bundles on the periplasmic side of LacY at the ends of helices II and XI (Gly46 and Gly370, respectively) and helices V and VIII (Gly159 and Gly262, respectively) (43). When Gly46 (helix II) and Gly262 (helix VIII) are replaced with bulky Trp residues (Fig. 1), transport activity is abrogated with little or no effect on galactoside binding (44). Moreover, site-directed alkylation and stopped-flow binding kinetics indicate that the G46W/G262W mutant is open on the periplasmic side (open outward). In addition, the detergent-solubilized mutant exhibits much greater thermal stability than WT LacY (44).Open in a separate windowFig. 1.Side view of LacY G46W/G262W molecules A (Center) and B (Left) in an almost occluded, outward-facing conformation shown in green and gray ribbons, respectively. The two molecules in the asymmetric unit are shown adjacent to one another from the perspective of the membrane plane. The two molecules have a similar conformation with bound TDG, and the Trp replacements at positions 46 and 262 are shown. TDG and the Trp replacements are represented as spheres, with carbon atoms in magenta (for Trp) or orange (for TDG), oxygen atoms in red, nitrogen atoms in blue, and sulfur in yellow. Dashed lines depict the quasi twofold axes relating the N- and C-terminal helix bundles. (Right) The change in structure between LacY G46W/G262W (green; helices numbered) versus the apo WT structure (PDB ID code 2V8N, blue). The orientation matches chain A, and the alignment of the two structures is based on alignment of the N-terminal six-helix bundle of the apo structure onto the G46W/G262W.The G46W/G262W mutant now has been crystallized in the presence of a high-affinity lactose analog. Remarkably, the structure presented here depicts an almost occluded, outward-open conformation with a reliably defined model of the bound sugar molecule.     

血管成形术和支架辅助血管成形术治疗颅内动脉粥样硬化的报告标准（上）

背景和目的颅内动脉粥样硬化可造成众多患者发生缺血性卒中。过去10年间血管内治疗技术已经取得突破性进展,能够开展颅内动脉粥样硬化性狭窄的血管内治疗。采用血管成形术和支架辅助阻管成形术治疗颅内动脉粥样硬化性狭窄的患者例数不断增加。但是鉴于目前血管成形术和支架辅助血管成形术治疗狭窄性和闭塞性颅内动脉粥样硬化仍缺乏普遍认可的临床和放射学评估以及皿管内治疗技术及预后的规范,此文就是提供该方面报告标准、术语和书面定义的共识性建议。报告摘要报告标准是在技术评价委员会、神经介入外科学会、介入放射学会、美国神经外科医师协会和神经外科医师代表大会的脑血管外科分会、美国神经科学会的卒中和介入神经病学分会的联合写作组共同起草完成。对1997年1月-2007年12月间,美国国立图书馆医学文献数据库（PubMed）进行计算机检索,旨在确定已发表的狭窄性颅内动脉粥样硬化的神经介入治疗中,能用作质量评价基准的资料。我们尽可能地确定影响神经介入治疗成功及并发症可能性的危险调节变量。对狭窄性和闭塞性颅内动脉粥样硬化进行麻管内治疗的临床试验设计中,不同临床和技术问题可能影响血管内治疗的疗效,此文章为这些问题提供相关的理论基础。该指南中包括对血管内治疗试验报告标准的建议。虽然制定规范和标准主要是出于研究用途,但是这也将有助于临床实践,还适用于所有相关的出版物。结论总之,报告标准提出的建议将有助于构建有效的研究数据库,同时促进产生科学可靠的研究结果,使相似研究之间或内部能够进行可靠的比较。存某些情况下,为报告和出版的一致性,本文中的定义可能是写作组专家的共识性建议。这些建议将促使不同研究组的结果具有直接可比性。     

Romantic and sexual activities, parent–adolescent stress, and depressive symptoms among early adolescent girls

Building on evidence that romantic experiences are associated with depressive symptoms in adolescence, we examined their bidirectional association, as well as the role of sexual activity and parent–adolescent stress in their association. Data were collected from 71 early adolescent girls (M age 13.45 years; SD = 0.68) and their primary caregiver initially and one year later. Results indicated that adolescents who engaged in more romantic activities experienced increases in depressive symptoms over time. Second, greater depressive symptoms predicted romantic involvement and sexual activities, including intercourse, one year later. Third, dysphoric adolescents who were experiencing higher parent–adolescent stress were the most likely to engage in subsequent sexual intercourse. Implications for understanding how the association between depressive symptoms and romantic and sexual experiences develops and the course of this association are discussed.     

Split-hand index for the diagnosis of amyotrophic lateral sclerosis

ObjectivePreferential wasting of the thenar group of muscles, the split hand sign, appears to be a specific feature of ALS. The present study developed a novel split-hand index (SI) and assessed its diagnostic utility in ALS.MethodsOne hundred and seventy consecutive patients with neuromuscular symptoms (44 ALS, 126 patients with other neuromuscular disorders) were prospectively recruited according to standards for reporting of diagnostic accuracy (STARD) criteria. The SI was derived by dividing the product of the compound muscle action potential (CMAP) amplitude recorded over the first dorsal interosseous and abductor pollicis brevis by the CMAP amplitude recorded over the abductor digiti minimi.ResultsThe SI was significantly reduced in ALS patients (ALS 3.5 ± 0.6; patients with other neuromuscular disorders 9.1 ± 0.3, P < 0.0001), particularly in limb-onset ALS (2.3 ± 0.5, P < 0.0001). Receiver operating characteristic curve analysis indicated that SI reliably differentiated ALS from patients with other neuromuscular disorders (area under curve ALS 0.83, P < 0.0001) with an optimal SI cut-off value of 5.2 exhibiting a sensitivity of 74% and specificity 80%.ConclusionsThe split-hand index robustly differentiates ALS from mimic disorders.SignificanceThe split-hand index is a simple measure that could be utilized in a standard neurophysiology setting. A reduction in SI distinguishes ALS from mimic disorders, potentially facilitating an earlier diagnosis of ALS.     

Rapid engraftment by peripheral blood progenitor cells mobilized by recombinant human stem cell factor and recombinant human granulocyte colony-stimulating factor in nonhuman primates

We have previously shown that administration of low-dose recombinant human stem cell factor (rhSCF) plus recombinant human granulocyte colony-stimulating factor (rhG-CSF) to baboons mobilizes greater numbers of progenitor cells in the blood than does administration of rhG-CSF alone. The purpose of the present study was to determine whether marrow repopulating cells are present in the blood of nonhuman primates administered low-dose rhSCF plus rhG-CSF, and if present, whether these cells engraft lethally irradiated recipients as rapidly as blood cells mobilized by treatment with rhG-CSF alone. One group of baboons was administered low-dose rhSCF (25 micrograms/kg/d) plus rhG- CSF (100 micrograms/kg/d) while a second group received rhG-CSF alone (100 micrograms/kg/d). Each animal underwent a single 2-hour leukapheresis occurring the day when the number of progenitor cells per volume of blood was maximal. For baboons administered low-dose rhSCF plus rhG-CSF, the leukapheresis products contained 1.8-fold more mononuclear cells and 14.0-fold more progenitor cells compared to the leukapheresis products from animals treated with rhG-CSF alone. All animals successfully engrafted after transplantation of cryopreserved autologous blood cells. In animals transplanted with low-dose rhSCF plus rhG-CSF mobilized blood cells, we observed a time to a platelet count of > 20,000 was 8 days +/- 0, to a white blood cell count (WBC) of > 1,000 was 11 +/- 1 days, and to an absolute neutrophil count (ANC) of > 500 was 12 +/- 1 days. These results compared with 42 +/- 12, 16 +/- 1, and 24 +/- 4 days to achieve platelets > 20,000, WBC > 1,000, and ANC > 500, respectively, for baboons transplanted with rhG-CSF mobilized blood cells. Animals transplanted with low-dose rhSCF plus rhG-CSF mobilized blood cells had blood counts equivalent to pretransplant values within 3 weeks after transplant. The results suggest that the combination of low-dose rhSCF plus rhG-CSF mobilizes greater numbers of progenitor cells that can be collected by leukapheresis than does rhG-CSF alone, that blood cells mobilized by low-dose rhSCF plus rhG-CSF contain marrow repopulating cells, and finally that using a single 2-hour leukapheresis to collect cells, the blood cells mobilized by low-dose rhSCF plus rhG-CSF engraft lethally irradiated recipients more rapidly than do blood cells mobilized by rhG- CSF alone.     

Normalization of Naxos plakoglobin levels restores cardiac function in mice

Arrhythmogenic cardiomyopathy (AC) is associated with mutations in genes encoding intercalated disc proteins and ultimately results in sudden cardiac death. A subset of patients with AC have the autosomal recessive cardiocutaneous disorder Naxos disease, which is caused by a 2–base pair deletion in the plakoglobin-encoding gene JUP that results in a truncated protein with reduced expression. In mice, cardiomyocyte-specific plakoglobin deficiency recapitulates many aspects of human AC, and overexpression of the truncated Naxos-associated plakoglobin also results in an AC-like phenotype; therefore, it is unclear whether Naxos disease results from loss or gain of function consequent to the plakoglobin mutation. Here, we generated 2 knockin mouse models in which endogenous Jup was engineered to express the Naxos-associated form of plakoglobin. In one model, Naxos plakoglobin bypassed the nonsense-mediated mRNA decay pathway, resulting in normal levels of the truncated plakoglobin. Moreover, restoration of Naxos plakoglobin to WT levels resulted in normal heart function. Together, these data indicate that a gain of function in the truncated form of the protein does not underlie the clinical phenotype of patients with Naxos disease and instead suggest that insufficiency of the truncated Naxos plakoglobin accounts for disease manifestation. Moreover, these results suggest that increasing levels of truncated or WT plakoglobin has potential as a therapeutic approach to Naxos disease.