Cell structure Lysosome

A 27-year-old white man seeks medical attention complaining of forgetfulness that has begun to interfere with his ability to work. Lately, he has stumbled over chores at work that he had been doing for years. He has also noticed that the dimensions of his facial features have changed over the past 3-4 years. He brought a 4-year-old photo of himself to show that the bony structures of his chin, cheeks, and forehead have become more prominent and coarser. Physical examination reveals angiokeratomas on his torso. Ultrastruc-tural examination shows that his skin cells have lysosomal inclusions. 

Intermediate-duration oral studies in rats have shown that high doses of DEHP can affect thyroid cell structure (e g., hypertrophy of Golgi apparatus, increases in lysosomes, dilation of the endoplasmic reticula, and increase in colloid droplets) and function (e.g., decrease levels of circulating T4) (Hinton et al. 1986 Poon et al. 1997 Price et al. 1987, 1988a). When large oral doses of 500 and 2,500 mg/kg/day DEHP were combined with dietary exposure to a compound which has similar effects on the thyroid (Aroclor 1254, a polychlorinated biphenyl mixture), there was an apparent additive effect of the two compounds on changes in thyroid cell structure and decreases in serum T3 and T4. At lower doses of DEHP (50 and 100 mg/kg/day) and Aroclor 1254 there were no additive effects apparent with the changes in cell structure or the levels of T3 and T4. 

In the olfactory mucosa of Wistar rats exposed four times a day to 175 ml cigarette smoke for 5,10, and 15 min, respectively, Ortug and Ozbek (2001) found intraepithelial inflammatory cells and especially deep invaginations at the nuclear membrane of supporting cells. Extension between extracellular space, cytoplasmic protrusions in the apical surface of the supporting cells, atrophy of the microvilli and olfactory neurone cilia and numerous electron-dense granular structures, lysosome-like structures were seen in relation to the times of exposure. 

Lysosome Contains hydrolytic enzymes that digest and recycle old cell structures... 

A problem with employment of ASON in a larger clinical setting is their poor uptake and inappropriate intracellular compartmentalization, e.g., sequestration in endosomal or lysosomal complexes. In addition, there is a need for a very careful selection of the ASON-mRNA pair sequences that would most efficiently hybridize. To date, several computer programs are used to predict the secondary and tertiary structures of the target mRNA and, in turn, which of the mRNA sequences are most accessible to the ASON. However, even with this sophisticated techniques, the choice of base-pairing partners still usually includes a component of empiricism. Despite these principal limitations, it has become clear that ASON can penetrate into cells and mediate their specific inhibitory effect of the protein synthesis in various circumstances. 

Details of the mechanisms by which endocytosed material moves from the early to the late and lysosomal compartment are still poorly understood. However, portions of the EEs tubulovesicular structures may be actively transported along microtubules towards the perinuclear region of the cell in both neurons and non-neuronal cells. These endosomes on the move may enclose invaginated membranes and also internally bud off vesicles. For that reason, these complex structures are called multivesicular bodies (MVBs) [76]. Material returning by retrograde axonal transport to the neuronal cell body includes many MVBs [67]. The eventual fate of these structures may vary. Some MVBs may fuse with LEs or they may fuse with each... 

Cathepsin K (Cat K) is a member of the CA1 family of lysosomal cysteine proteases. This family is comprised of 11 human members (cathepsins B, C, F, H, K, L, O, S, V, W, Z) which share a common papain-like structural fold and a conserved active site Cys-Asn-His triad of residues [1-3]. These enzymes are synthesized as pre-pro-enzymes and are converted from the catalytically inactive zymogen into the active form in acidic lysosomal environment. In some cases, cathepsins are also secreted in the active form from cells. The sequence identity of... 

---