FT-IR photoacoustic depth profiling spectroscopy of enamel

Photoacoustic Fourier transform infrared (PA-FT-IR) depth profiling spectra of the enamel of an intact human tooth are obtained in a completely nondestructive fashion. The compositional and structural changes in the tissue are probed from the enamel surface to a depth of about 200 m. These changes reflect the state of tissue development. The subsurface carbonate gradient in the enamel could be observed over the range of about 10–100 m. The carbonate-to-phosphate ratio increases in the depth profile. The depth profile also reveals changes in the substitutional distribution of carbonate ions. Type A carbonates (hydroxyl substituted) increase relative to type B carbonates (phosphate substituted) with increasing thermal diffusion length. In addition to the changes in the carbonate ion distribution and content, the PA-FT-IR depth profile clearly indicates a dramatic increase in the protein content relative to the phosphate content with increased depth. The changes in the carbonate content and distribution, along with the changes in the protein content, may be responsible for the changes observed in the apatitic structure in the depth profile of the enamel.     

Mucoadhesion of Latexes. I. Analytical Methods and Kinetic Studies

A Fourier transform infrared spectroscopy/attenuated total reflection technique for direct quantification of adsorbed poly(styrene) latexes on rat intestinal mucosa was developed for deposited latex amounts up to 1.5 g/m². The method agreed well with another dosage assay of adsorbed particles by turbidimetry after denaturation of the mucus. Adsorption kinetics were made under static conditions at latex concentrations of 4 g/L in physiological saline. Ninety percent of equilibrium was reached after 10 min for a particle size of 230 nm, 20 min for a size of 320 nm, and 30 min for a size of 670 nm. The plateaus were between 0.6 and 0.9 g/m² (adsorbed mass per apparent surface of mucosa). The first phase of the kinetics was theoretically approached by a diffusion model in the suspension medium. Mucosa from rat jejunum and ileum could be considered as a homogeneous biological model for latex adsorption.     

Effects of sciatic neurectomy on the femur in growing rats: Application of peripheral quantitative computed tomography and Fourier transform infrared spectroscopy

The effects of unilateral sciatic neurectomy (USN) on the development of the femur were studied in 15 growing Wistar-derived rats (age, 5 weeks). The rats were divided into four groups: USN-operated group (right femur), USN-nonoperated group (left femur), sham-operated group (right femur), and sham-nonoperated group (left femur). Bone mineral density (BMD), bone mineral content (BMC), bone area, periosteal circumference, and endosteal circumference were measured by peripheral quantitative computed tomography (pQCT) and the mineral/matrix ratio was evaluated by Fourier transform infrared spectroscopy (FTIR). The USN-operated group showed a significant decrease in cortical BMC, bone area, and periosteal circumference compared with the other groups (P < 0.05). The cortical BMD did not vary significantly between the groups. In the cancellous bone, the USN-operated group showed a significant decrease in BMD and BMC at the metaphysis compared with the other groups (P < 0.05). The mineral/matrix ratio of the cortical bone did not differ significantly between the USN-operated and USN-nonoperated groups. These results suggest that in cortical bone, USN inhibits periosteal bone formation but has no significant effect on the mineral/matrix ratio of cortical bone in femurs. In cancellous bone, USN induces bone loss at the metaphysis. Received: Nov. 19, 1998 / Accepted: Feb. 12, 1999     

周围型肺癌阻塞性病变的CT表现

目的：确定ＣＴ 图像上周围型肺癌之肺部阻塞性病变的诊断作用。方法：１８ 例周围型肺癌和１２ 例良性肺肿块对照者均经常规ＣＴ 扫描,绝大多数病人经肿块部位及其上下一层的深呼吸时相ＣＴ 扫描。结果：周围型肺癌的肺部阻塞性病变计有肺不张、阻塞性肺炎、阻塞性肺气肿及肺静脉癌栓。结论：注重ＣＴ 图像上周围型肺癌的各种肺部阻塞性病变,可为肺癌确诊提供重要的诊断依据。     

益气活血中药对放射性骨损伤防护作用的实验研究

目的 :探讨益气活血中药防治放射性骨损伤的作用。方法 :60Coγ射线一次 3 0Gy照射兔后腿造模 ,实验组用中药 6个月 ,对照组不做治疗。不同时相观察照射部位骨细胞、血管变化、血管铸型、血流情况。结果 :骨细胞变性坏死在呈持续发展 ,尤其第 6周时尤为明显 ,对照组为 2 7% ,实验组为 8% ,差异明显 ,血管铸型 1 3周血管网逐增加 ,呈囊性扩张融合成片 ,以后渐减少 ,2 4周时实验组血管数目明显多于对照组。血流两组 3周时为著 ,6周后呈持续下降 ,但对照组明显 (P <0 .0 1 )。讨论 :益气活血中药能减轻射线对骨细胞及其它组织的直接杀伤 ,减轻对骨血管损伤 ,改善骨微循环及血流。     

中西医结合治疗宫颈糜烂50例观察

目的：观察恒和坤净栓联合波姆红外光治疗宫项糜烂的疗效。方法：中西医结合组50例用恒和坤净检与波姆红外光治力仪联合治疗；对照组50例，单用波姆红外光治疗仪治疗。结果：中西医结合组痊愈率82％，对照组痊愈率40％。结论：中西医结合疗效较好，优于单用西医治疗。     

紫石英和寒水石超微饮片粉末粒径的研究

目的：为矿物类药材超微粉末粒径提供试验数据。方法：采用电镜扫描，X射线定性，原子发射光谱定量。结果：选择粒度为K4的微粉制备超微饮片，Ca^2 成分溶出度较高。结论：使用超微紫石英和寒水石，会减少服用量。     

13例肝局灶性结节增生的CT和MR诊断

目的 探讨肝脏局灶性结节增生(FNH)的CT和MR表现及诊断价值。方法 回顾分析13例经手术病理证实为肝脏FNH的CT和MR表现，研究其影像的诊断价值。结果 13例FNH的CT和MR中7例表现较为典型，CT平扫等密度，T1WI为等信号，T2WI为等信号或稍高信号；部分病灶可见中央区低密度瘢痕，增强动脉期除中央瘢痕外均明显强化，门静脉期常见明显强化，延时期多为等密度，瘢痕可稍有强化；术前作出正确诊断。6例FNH表现不典型，CT低密度灶，T1WI为低信号，T2WI为高信号，无瘢痕和轻度强化；术前3例诊断为恶性肿瘤，3例诊断为血管瘤。结论 FNH的CT和MR表现在术前进行综合分析，多数可明确诊断。     

包裹在脂质体内部胰岛素的二级结构

目的以单纯胰岛素为对照，采用傅立叶红外光谱（Fourier transform infrared， FTIR）研究包裹在脂质体内部胰岛素二级结构的变化。方法分别对单纯胰岛素、胰岛素与空白脂质体混合物（样品I）及包裹胰岛素的脂质体（II）样品进行测定。结果样品I和样品II中胰岛素的FTIR谱图形状与单纯胰岛素相比基本一致，仅α-螺旋百分比略有下降（由36.09%分别下降到31.68%和31.45%），β-折叠百分比略有增加（由47.83%分别增加到53.29%和51.36%）。样品I和样品II中胰岛素的二级结构无明显差别（α-螺旋百分比为31.68%和31.45%，β-折叠百分比为53.29%和51.36%）。结论包裹在脂质体内部胰岛素的二级结构与单纯胰岛素相比无明显变化。     

New tools for the control of peptide conformation: the helicogenic Cα‐methyl,Cα‐cyclohexylglycine*

Abstract: The novel C^α‐tetrasubstituted α‐amino acid C^α‐methyl, C^α‐cyclohexylglycine was prepared by hydrogenation of its C^α‐methyl, C^α‐phenylglycine precursor. Terminally protected homodi‐, homotri‐, and homotetrapeptides from C^α‐methyl, C^α‐cyclohexylglycine and co‐oligopeptides to the pentamer level in combination with Gly or α‐aminoisobutyric acid residues were prepared by solution methods and fully characterized. The results of a conformational analysis, performed by use of Fourier transform infrared (FT‐IR) spectrophotomet absorption, ¹H NMR, and X‐ray diffraction techniques, support the contention that this C^α‐methylated, C^β‐trisubstituted aliphatic α‐amino acid is an effective β‐turn and 3₁₀‐helix inducer in tri‐ and longer peptides as its C^α‐methyl valine parent compound, but partially divergent from the corresponding aromatic C^α‐methyl, C^α‐diphenylmethylglycine residue, known to promote folded and fully extended structures to a significant extent in these oligomers.