Archive | October 2010

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Chapter 7 – Principles of Lasers

Chapter 7 – Principles of Lasers NEAL H. ATEBARA EDMOND H. THALL DEFINITION • “Laser” is an acronym for light amplification by stimulated emission of radiation. KEY FEATURES • Lasers have had a greater impact on ophthalmology than on any other medical specialty, largely because the transparent nature of the ocular tissues allows laser light […]

Chapter 6 – Light Damage to the Eye

Chapter 6 – Light Damage to the Eye DAVID MILLER CLIFFORD A. SCOTT DEFINITION • Structural or functional damage to the external or internal eye from thermal or photochemical effects of the absorption of light. KEY FEATURES • With age, many of the photoprotective mechanisms of the eye degrade. • Cataract development and the risk […]

CHAPTER 3 BIOSYNTHESIS AND SECRETION OF PEPTIDE HORMONES(cont’4)

GENERATION OF DIVERSITY A major example of the generation of diversity is the calcitonin and calcitonin gene–related peptide (CGRP) system. In this system, the C cell of the thyroid expresses a calcitonin-CGRP transcript that initially contains six exons. In the C cell, tissue-specific factors determine the use of the polyadenylation site in the fourth exon, […]

Chapter 5 – Physical Optics for Clinicians

Chapter 5 – Physical Optics for Clinicians EDMOND H. THALL RUSSELL MILLER CHRISTOPHER CALVANO DEFINITION • Whereas geometrical optics considers light to be a series of rays, physical optics approaches problems in optics by treating light as a waveform. KEY FEATURES • Interference of light waves. • Polarization of light waves. • Diffraction effects of […]

CHAPTER 3 BIOSYNTHESIS AND SECRETION OF PEPTIDE HORMONES(cont’3)

As protein synthesis continues, the signal peptide is transiently immobilized in the membrane by virtue of its hydrophobic nature or its binding to a putative signal peptide receptor.41,42 Although the nascent protein chain is transferred to the cisterna by way of an unknown, energy-dependent translocation process, a luminal surface enzyme, signal peptidase, rapidly performs proteolytic […]

CHAPTER 3 BIOSYNTHESIS AND SECRETION OF PEPTIDE HORMONES(cont’2)

The initiation of transcription by RNA polymerase II often is the rate-limiting step in gene expression and is determined by the interaction of the enzyme with a number of nuclear factors and DNA elements in the regulatory region of the transcription unit.11,12 Two types of elements participate in regulation of transcription of the typical eukaryotic […]

CHAPTER 3 BIOSYNTHESIS AND SECRETION OF PEPTIDE HORMONES

CHAPTER 3 BIOSYNTHESIS AND SECRETION OF PEPTIDE HORMONES Principles and Practice of Endocrinology and Metabolism CHAPTER 3 BIOSYNTHESIS AND SECRETION OF PEPTIDE HORMONES WILLIAM W. CHIN Overview of Peptide Hormone Synthesis and Secretion Gene Structure Messenger RNA Processing RNA Transport Translation Posttranslation Secretory Granule Secretion Regulation of Polypeptide Hormone Synthesis Generation of Diversity Chapter References […]

Part 2 – OPTICS and REFRACTION

Part 2 – OPTICS and REFRACTION David Miller 29 30 31 Chapter 4 – Visible Light DAVID MILLER STEPHEN K. BURNS DEFINITION • Visible light represents a small portion of the electromagnetic spectrum; wavelengths range between 400 and 700?nm. KEY FEATURES • The main source of visible light is the Sun. • The Earth’s atmosphere […]

CHAPTER 2 MOLECULAR BIOLOGY: PRESENT AND FUTURE(cont’4)

Retroviral Vectors. The Moloney murine leukemia virus (MoMuLV) was the first virus used in developing a vector system for gene transfer. Parts of the retroviral genome that are involved in the replication of the MoMuLV—gag, pol, and env—are removed and replaced by a gene of interest. What remains of the retrovirus are the long terminal […]

CHAPTER 2 MOLECULAR BIOLOGY: PRESENT AND FUTURE(cont’3)