5－乙基－5－对氟苯甲酰丙基巴比妥酸在兔体内的代谢产物研究

用高效液相色谱法对５－乙基－５－对氟苯甲酰丙基巴比妥酸在家兔体内的代谢物进行了分离，用二极管阵列检测器测定了原药及代谢物紫外图谱，得出代谢物的紫外吸收性质；同时测试了原药及代谢物的质谱，推测出代谢物的可能结构，并用化学方法合成了代谢物对照品，通过核磁和质谱的测定进一步确证了结构。     

Orbital lesions: proton spectroscopic phase-dependent contrast MR imaging

Thirteen orbital lesions in 12 patients were evaluated with both conventional spin-echo magnetic resonance (MR) imaging and phase-dependent proton spectroscopic imaging. This technique, which makes use of small differences in the resonant frequencies of water and fat protons, provides excellent high-resolution images with simultaneous chemical shift information. In this method, there is 180 degrees opposition of phase between fat protons and water protons at the time of the gradient echo, resulting in signal cancellation in voxels containing equal signals from fat and water. In this preliminary series, advantages of spectroscopic images in orbital lesions included better lesion delineation, with superior anatomic definition of orbital apex involvement; more specific characterization of high-intensity hemorrhage with a single pulse sequence; elimination of potential confusion from chemical shift misregistration artifact; further clarification of possible intravascular flow abnormalities; and improved apparent intralesional contrast.     

Trisomy 21 in newborn infants: chest radiographic diagnosis

Chest radiographs of 30 infants with trisomy 21 and 881 unaffected infants were evaluated for the following findings common in trisomy 21: multiple manubrial ossification centers, 11 rib pairs, and a bell-shaped chest. Radiographs were obtained in the first 48 hours of life. Of the 881 unaffected infants, 85 (9.6%) exhibited multiple manubrial ossification centers; 46 (5.2%), 11 rib pairs; and 208 (23.6%), bell-shaped chest. Of the 30 infants with trisomy 21, 24 (80%) exhibited multiple manubrial ossification centers; ten (33%), 11 rib pairs; and 24 (80%), bell-shaped chest. The probability of trisomy 21 in routinely radiographed newborn infants is 0.05% when none of the three findings is present, 1.6% with multiple manubrial ossification centers alone, 0.2% with 11 rib pairs alone, and 0.7% with bell-shaped chest alone. The probability of trisomy 21 increases in patients with two findings and reaches 58.4% in patients with all three findings.     

Phosphate, alkaline phosphatase and bone mineralization in preterm neonates

We examined the relationship between bone mineralization, measured by single photon absorptio-metry, and blood phosphate and alkaline phosphatase concentration in 71 preterm neonates. Although both alkaline phosphatase and phosphate concentrations were significantly related to bone mineral content, and alkaline phosphatase concentrations were related to bone mineral content relative to weight, each could only explain a small amount of the variation in bone mineralization. Hence, concentrations of neither could be used to identify those neonates with the greatest bone mineral deficits.     

Vascular intracranial lesions: applications of gradient-echo MR imaging

To investigate the role of the gradient-echo (GRE) technique in clinical intracranial magnetic resonance (MR) imaging, 63 patients with a variety of vascular intracranial lesions were examined at 1.5 T with the use of spin-echo (SE) and GRE sequences. In all cases, the sequential section acquisition technique called gradient recalled acquisition in the steady state (GRASS) was employed; a repetition time of 150-200 msec, an echo time of 13-16 msec, and a flip angle of 50 degrees-60 degrees were used to optimize the depiction of blood flow as high intensity and the depiction of stationary fluid as low intensity. In 61 of 63 cases, gradient moment nulling was utilized to compensate for first-order flow effects. Although GRE images rapidly demonstrated flow in vascular intracranial lesions as high intensity, the vascular nature of these lesions was also clearly evident on SE images in most cases. In some cases, GRE images can be used to clarify the vascular nature of a lesion or to characterize a neoplasm. Other applications include the detection of vascular thrombosis, occult vascular malformations, and hemorrhagic complications of vascular lesions.     

Synergy between cyclosporin A and a monoclonal antibody to B7 in blocking alloantigen-induced T-cell activation

Costimulatory signals are absolutely required for T-cell activation after T-cell receptor/major histocompatibility complex-peptide interaction. So far, the best-known candidate essential costimulatory signal is mediated by interaction of CD28 on T cells with B7 on antigen- presenting cells. Using an allogeneic B7+ Epstein-Barr virus- transformed B-cell line as stimulator, we found that addition of a monoclonal antibody (MoAb) to B7 that efficiently blocks B7-CD28 interaction only partially inhibited proliferation and interleukin-2 (IL-2) production in primary and secondary mixed lymphocyte reactions (MLR), whereas the generation of cytotoxic T lymphocytes (CTL) was not affected. Inhibition of primary or secondary MLR-induced T-cell activation with cyclosporin A (CsA) at nontoxic concentrations also was never complete. However, the combination of CsA and anti-B7 MoAb B7-24 synergistically blocked allogeneic B cell-induced T-cell proliferation, IL-2 production, and CTL generation. These data suggest that the mere blockage of B7-CD28 interaction during allotransplantation will be insufficient to prevent rejection or graft-versus-host disease. However, low CsA concentrations, when combined with an agent blocking B7-CD28 interaction, can potentially achieve complete immunosuppression.     

Pediatric thoracic aorta: normal measurements determined with CT

Normal thoracic aortic dimensions in adults have been established by means of computed tomography (CT), but such measurements are not available in children. To establish normal standards, contrast material-enhanced chest CT scans of 117 children and adolescents, ranging in age from 2 weeks to 19 years, were reviewed retrospectively. Patients with congenital heart disease, vascular anomalies, renal disease, hypertension, and connective-tissue disorders were excluded, resulting in 97 studies. Diameters of the thoracic aortas were measured at three levels. Interobserver and intraobserver variances were determined. A direct linear relationship to patient age was observed, and regression analysis was performed. These standards help in differentiating the normal from the abnormal aorta on chest CT scans of children.     

Progressive and regressive changes in the nucleus pulposus. Part II. The adult

The spines of 28 cadavers were studied with magnetic resonance (MR) imaging, correlated with anatomic sections, to characterize the progressive and regressive changes in the nucleus pulposus. Four additional types of nucleus pulposus were identified in this study. The transitional type (type II) of childhood had fibrous tissue that developed near the anulus fibrosus anteriorly or posteriorly. MR images showed a notch of reduced signal intensity in the nucleus pulposus where the fiber was developing. The adult type (type III), which is predominant after age 30 years, had an indistinct boundary between the nucleus pulposus and anulus fibrosus. MR images showed the fibrocartilage in the nucleus pulposus and inner anulus fibrosus as areas of high signal intensity. Adult disks with a tear of the anulus fibrosus (type IIIB) had a lower signal intensity on MR images and slightly reduced disk heights. This type may represent an early stage of degeneration. Degenerated intervertebral disks (type IV) had either dense disorganized fibrous tissue or fluid replacing the normal fibrocartilaginous structure of the nucleus pulposus. MR images showed narrow intervertebral disk spaces with either reduced signal intensity if collagen was present or increased signal intensity if fluid was present. This study suggests that the nucleus pulposus may progress normally through types I, II, and III.