Structure and conformation of linear peptides XII. Structure of tryptophanyl-glycyl-glycine dihydrate

The crystal structure of a tripeptide, tryptophanyl-glycyl-glycine dihydrate (C₁₅H₁₈N₄O₄·2H₂O, molecular weight = 354) has been determined. The crystals are orthorhombic, space group P2₁2₁2₁ with a= 7.875 (1) A,b= 9.009(1), c= 24.307(1) and Z = 4. The final R-index is 0.058 for 1488 reflections ((sin θ/λ≤ 0.6 A^?1) with I < 2σ(I). The molecule exists as a zwitterion, with terminal NH⁺₃ and COO^? groups. The peptide units are trans and nearly perpendicular to the plane of the carboxyl group. The backbone torsion angles are: ψ₁= 132.7°, ω₁= 174.2°, φ₂ 88.2°, ψ= 8.6°, ω₂ - 179.8°, φ= - 85.2°, ψ₃₁, = - 178.1°, ψ₃₂ 5.0°. For the sidechain of tryptophan, χ₁= - 171.6°, χ₂ 101.0°.     

Rehabilitation of a Spark Erosion Prosthesis: A Clinical Report

When complex prostheses are fabricated, it is expected that at some point maintenance will be necessary. This clinical report documents a 10-year-old maxillary spark erosion prosthesis that had been repaired many times, was discolored, and exhibited significant signs of wear. The metal superstructure was intact; therefore, only the acrylic resin base and teeth needed to be replaced. To reduce both cost and time without the prosthesis for the patient, the rehabilitation was completed within 24 hours.     

Spontaneous Neoplasms in Control Wistar Rats

Neoplastic data on 1370 control Wistar rats from 10 carcinogenicitybioassays done between 1980 and 1990 were reviewed. Mean percentagesurvival at 104 weeks was 58% for males and 59% for females.A total of 1857 neoplasms were diagnosed in 466 (68%) male and582 (85%) female rats; 1390 were benign and 467 were malignant(12% with metastasis). Seventy-four percent of all neoplasmswere in endocrine and reproductive systems. Most common neoplasms(affecting more than 7% of either sex) were pituitary adenoma(27.7% males; 55.0% females), mammary fibroadenoma (1.0% males;25.3% females), mammary adenocarcinoma (1.0% males; 13.1% females),adrenal cortical adenoma (8.3% males; 9.3% females), and endometrial stromal polyp (9.6% females). Fourteen neoplasms affecting2 to 6% of either sex included adrenal pheochromocytoma, thyroidC cell adenoma, thyroid follicular adenoma, pancreatic isletcell adenoma, lymphoma, histiocytic sarcoma, thymoma, hepaticadenoma, pancreatic acinar adenoma, mammary adenoma, dermalfibroma, astrocytoma, testicular interstitial cell tumor, andovarian granulosa cell tumor. Remaining neoplasms were seenin less than 2% of animals.