Cisterna

Crystallization-based separation of multi-component mixtures has widespread application. The technique consists of sequences of heating, cooling, evaporation, dilution, diluent addition and solid-liquid separation. Berry and Ng (1996, 1997), Cisternas and Rudd (1993), Dye and Ng (1995), Ng (1991) and Oyander etal. (1997) proposed various schemes based on the phase diagram. Cisternas (1999) presented an alternate network flow model for synthesizing crystallization-based separations for multi-component systems. The construction... 

Figure 9.10 (a) Solution flow, and (h) corresponding flow sheet for the separation by crystallization of astrakanite (Cisternas, 1999)... 

Cisternas, L.A., 1999. Optimal design of crystallization-based separation systems. American Institute of Chemical Engineers Journal, 45, 1477-1487. 

Cisternas, L.A. and Rudd, D.F., 1993. Process designs for fractional crystallization from solution. Industrial and Engineering Chemistry Research, 32, 1993. 

Oyanader, M.A., Guerrero, C.J. and Cisternas, L.A., 1997. SSS, salt separation system by fractional crystallization. Information Technology, 8, 11. 

FIGURE 17.25 The structures of nifedipine and ryanodine. Nifedipine binds with high affinity to the Ca" -release channels of t-tubules. Ryanodine binds with high affinity to the Ca" channels of SR terminal cisternae. 

FIGURE 17.27 (a) Electron micrograph images of foot structures of terminal cisternae. (b, c) Foot structures appear as trapezoids and diamonds on the surface of the membrane. 

The central canal (CC), radial canals (RC), and peripheral vestibules (PV) are indicated, (d) The relationship between the foot structures, t-tubule, terminal cisternae, and muscle fiber. (Photo courtesy of Sidney Fleischer, Vanderbilt University)... 

So how do the foot structures effect the release of Ca from the terminal cisternae of the SR The feet that join the t-tubules and the terminal cis-ternae of the SR are approximately 16 nm thick. The feet apparently function by first sensing either a voltage-dependent conformation change (skeletal mus-... 

The structure of heart myocytes is different from that of skeletal muscle fibers. Heart myocytes are approximately 50 to 100 p,m long and 10 to 20 p,m in diameter. The t-tubules found in heart tissue have a fivefold larger diameter than those of skeletal muscle. The number of t-tubules found in cardiac muscle differs from species to species. Terminal cisternae of mammalian cardiac muscle can associate with other cellular elements to form dyads as well as triads. The association of terminal cisternae with the sarcolemma membrane in a dyad structure is called a peripheral coupling. The terminal cisternae may also form dyad structures with t-tubules that are called internal couplings (Figure 17.31). As with skeletal muscle, foot structures form the connection between the terminal cisternae and t-tubule membranes. 

In higher animals, large percentages of the terminal cisternae of cardiac muscle are not associated with t-tubules at all. For SR of this type, Ca release must occur by a different mechanism from that found in skeletal muscle. In this case, it appears that Ca leaking through sarcolemmal Ca channels can trigger the release of even more Ca from the SR. This latter process is called Ca -induced Ca release (abbreviated CICR). 

FIGURE 17.31 Electron micrograph of a dog heart muscle. The terminal cisterna of the SR (TC-SR) is associated with the t-tnbnle (TT) by means of foot strnctnres (FS), forming a dyad junction. ME indicates the location of myofilaments. LT-SR signifies the longitudinal tubule of the SR. (From Fteischer,. S ., and Inni, M., 1989. Amiual Review of Biophysics and. Biophysical Chemisti y 18 333-364.)... 

A system of membrane enclosed cisternae in the cytoplasm. The ER is continuous with the outer membrane of the nuclear envelope. The part of the ER coated with ribosomes is called rough ER, the other part is called smooth-surfaced ER. The rough ER is the first compartment of the secretory pathway. Here, membrane proteins are integrated into and secretory proteins translocated across the ER membrane. Furthermore,... 

S100A1 is the most abundant in the myocardium but is also expressed in brain and other tissues. S100A1 was found to stimulate Ca2+-induced Ca2+-release (CICR) in skeletal muscle terminal cisternae. In the presence of nanomolar Ca2+-concentrations, S100A1 binds to the ryanodine receptor increasing its channel open probability, and was shown to enhance SR Ca2+-release and contractile performance. Several animal models (over expressing S100A1 or S100A1-deficient mice) have... 

In striated muscles, SR is well developed to surround the myofibrils and is divided into two parts, the terminal cisternae (TC) and longitudinal tubules (LT). TC forms triad (skeletal muscle) or dyad (heart) structure with transverse tubules. The ryanodine receptor is located only in the TC, whereas the Ca2+ pump/SERCA is densely packed in both TC and LT. 

Figure 49-8. Diagram of the relationships among the sarcolemma (plasma membrane), a T tubule, and two cisternae of the sarcoplasmic reticulum of skeletal muscle (not to scale). The T tubule extends inward from the sarcolemma. A wave of depolarization, initiated by a nerve impulse, is transmitted from the sarcolemma down the T tubule. It is then conveyed to the Ca release channel (ryanodine receptor), perhaps by interaction between it and the dihydropyridine receptor (slow Ca voltage channel), which are shown in close proximity. Release of Ca from the Ca release channel into the cytosol initiates contraction. Subsequently, Ca is pumped back into the cisternae of the sarcoplasmic reticulum by the Ca ATPase (Ca pump) and stored there, in part bound to calsequestrin.

Albumin (69 kDa) is the major protein of human plasma (3.4-4.7 g/dL) and makes up approximately 60% of the total plasma protein. About 40% of albumin is present in the plasma, and the other 60% is present in the extracellular space. The liver produces about 12 g of albumin per day, representing about 25% of total hepatic protein synthesis and half its secreted protein. Albumin is initially synthesized as a preproprotein. Its signal peptide is removed as it passes into the cisternae of the rough endoplasmic reticulum, and a hexapeptide at the resulting amino terminal is subsequently cleaved off farther along the secretory pathway. The synthesis of albumin is depressed in a variety of diseases, particularly those of the liver. The plasma of patients with liver disease often shows a decrease in the ratio of albumin to globulins (decreased albumin-globuhn ratio). The synthesis of albumin decreases rela-... 

FIGURE 1-5 Detail of the nuclear envelope showing a nuclear pore (single arrow) and the outer leaflet connected to the smooth endoplasmic reticulum (ER) (double arrows). Two cisternae of the rough ER with associated ribosomes are also present. X80,000. 

Subsurface cisternae are a system of smooth, membrane-bound, flattened cisternae that can be found in many neurons. These structures, referred to as hypolemmal cisternae by Palay and Chan-Palay [1], abut the plasmalemma of the neuron and constitute a secondary membranous boundary within the cell. The distance between these cisternae and the plasmalemma is usually 10-12 nm and, in some neurons, such as the Purkinje cells, a mitochondrion may be found in close association with the innermost leaflet. Similar cisternae have been described beneath synaptic complexes, but their functional significance is not... 

FIGURE 1-6 A portion of a Golgi apparatus. The smooth-mem-braned cisternae appear beaded. The many circular profiles represent tangentially sectioned fenestrations and alveolate vesicles (primary lysosomes). Two of the latter can be seen budding from Golgi saccules (arrows). Mitochondria and a dense body (secondary lysosomes) are also present. x60,000. 

FIGURE 1-10 An axonal terminal at the surface of a neuron from the dorsal horn of a rabbit spinal cord contains both dense-core and clear, spherical synaptic vesicles lying above the membrane thickenings. A subsurface cisterna (arrow) is also seen. x68,000. 

Biosynthetic and secretory cargo leaving the ER is packaged in COPII-coated vesicles for delivery to the Golgi complex 146 The Golgi apparatus is a highly polarized structure consisting of a series of flattened cisternae, usually located near the nucleus and the centrosome 146... 

Processing of proteins in the Golgi complex includes sorting and glycosylation of membrane proteins and secretory proteins 148 Proteins and lipids move through Golgi cisternae from the cis to the trans direction 148... 

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