Membrane lesions

Tab. 4.32 Molecular parameters describing the (glyco)lipids constituting the bilayer leaflet at the side of PMB addition of various asymmetric planar bilayers (the second leaflet was always made from the phospholipid mixture) and the average diameters of the induced membrane lesions. (Reprinted from Tab. 1 of ref. 117 with permission from Bertelsmann-Springer.)...

HS was first described in 1871 by Vanlair and Masius (Vanlair and Masius, 1871). They reported a young woman who had repeated attacks of abdominal pain and jaundice and found that some of her erythrocytes were spherical and much smaller than normal. In 1907, Chauf-fard (Chauffard, 1907) demonstrated increased osmotic fragility of erythrocytes as the hallmark of the disease. A membrane lesion was first suggested by the observation of Bertles in 1957 (Bertles, 1957) that HS red cells are unusually permeable to sodium ions. Since then, many abnormalities have been reported in HS red cells, but it is now clear that HS is a consequence of heterogeneous defects in the red cell membrane proteins. 

It is now clear that a deficiency or dysfunction of ankyrin, the protein that anchors the spectrin-based skeleton to band 3 (Fig. 6-3), may represent a common membrane lesion in HS. The synthesis of ankyrin and its assembly on the membrane were reduced, and as a consequence, assembly of spectrin was also impaired despite normal spectrin synthesis. In 1996,Jarolim et al. showed that a deficiency of ankyrin (and its related spectrins) was present in 60% of 166 unrelated patients with HS. 

TARGETING CELL MEMBRANE LESION WITH CYTOSKELETAL-ANTIGEN SPECIFIC IMMUNOLIPOSOMES... 

Anchoring CSIL to exposed myosin through membrane lesion... 

Khaw, B.A. Torchilin, V.P. Vural, I. Narula, J. Plug and seal prevention of hypoxic cardiocyte death by sealing membrane lesions with antimyosin-liposomes. Nature Med. 1995,1, 1195-1198. 

Pores formed by PFTs are usually fairly well defined in size, so that judicious choice of toxin and of experimental conditions will generally enable one to produce stable membrane lesions ranging from approximately 8 A to 300 A in functional diameter. It becomes possible to manipulate the intracellular ionic milieu, to introduce small molecules such as nucleotides into the cells, or to apply large molecules such as antibodies to the cytoplasm. Since pure preparations of PFT are devoid of enzymatic (proteolytic) activity, they cause no direct alterations of cell constituents. In the following, simple strategies for utilization of PFTs will be outlined. 

This chapter will be limited to the description of CSIL therapy to ex vivo studies in adult mammalian hearts. Due to page limitations, cell culture, gene delivery and in vivo studies will not be included. Therapeutic efficacy of CSIL in preservation of myocardial viability as well as function (by left ventricular developed pressure measurements) as assessed in globally ischemic Langendorff instrumented hearts is both dose and time dependent. This approach of cell membrane lesion repair and sealing may have broader applications in other cell systems. 

Targeted Sealing of Cell Membrane Lesions Model of Preservation of Cell Viability by Immunoliposome Therapy... 

Our studies support the hypothesis that cardiac cell membrane lesion sealing with CSIL result in preservation of myocardial viability, as determined by function, histochemistry, and ultra-structural morphology. There is a time response to myocardial preservation with CSIL therapy. Early CSIL intervention after the onset of ischemia resulted in almost complete myocardial recovery (18). Even when the intervention was initiated at 20 min of global ischemia, myocardial preservation was still greater than that seen in hearts with IgG-L or placebo treatment. There is also a dose response to CSIL therapy. Sufficient concentration of CSIL is essential to achieve optimal cell membrane lesion sealing (I9).Therefore, CSIL therapy may find therapeutic applications in preservation of myocardial viability and efficient non-viral gene therapy. 

This benefit persisted even with late administration of CSIL. However, there is a time-dependent delay in the recovery to near normal LVDP with a delay in the initiation of CSIL therapy (Figs, lb, 2a, b), which may be due to the need for more extensive myocardial cell membrane lesion sealing. The IgG-liposomes may temporarily plug membrane lesions without fusion with the cell membrane, ultimately leading to myocardial cell death, as determined by NET. Nonetheless, the LVDP of IgC-L-treated hearts was still lower than that of CSIL treated hearts (17, 18). 

Treatment with CSIL enables globally ischemic hearts to return to near normal function within 15 min of reperfusion, which is consistent with the prevention of the occurrence of uncontrolled myocardial Ca overload. The absence of mitochondrial swelling and the return of function to near normal in CSIL-treated hearts are also consistent with the maintenance of Ca homeostasis. Cell membrane lesion sealing with neutral immunoliposomes may also reduce injury mediated by acid and oxidative stress. However, plain liposomes in serum-free... 

Khaw BA, Torchilin VP, Virral I, Narula J (1995) Plug and seal prevention of hypoxic cell death by sealing membrane lesions with cytoskeleton-specific immimoliposomes. Nat Med 1 1195-1198... 

We have hypothesized and then experimentally demonstrated that antibody-directed liposomes specific for an intracellular cytoskeletal antigen can have two important medical applications prevention of hypoxia-induced release of intracellular contents and subsequent cell death by sealing (plugging) membrane lesions with such ILs, and use of ILs for the targeted intracellular delivery of pharmacologically important substances, such as drugs or genetic constructs. 

The hallmark of necrotic cell death is the loss of cell membrane integrity as evidenced by the presence of cell membrane lesions. Antimyosin antibody, a... 

Further studies have demonstrated that IL-treated hypoxic cells were growing normally for more than 7 d after the hypoxic event when subsequently cultured under normoxic conditions. These treated cells were able to replicate normally. Prevention of cell death by cell-membrane-lesion sealing as described above could have significant clinical utility. 

Khaw, B. A., Vural, I., Narula, J., and Torchilin, V. P. (1995) Targeted sealing of cell membrane lesions model of preservations of cell viability by immuno-liposome therapy. Proceedings of the 22nd International Symposium on Controlled Release of Bioactive Materials, Seattle, WA. Controlled Release Society, pp. 184-185. 

Thus, there are already available expert systems for differential diagnostics of many pathological conditions, such as diseases of red and white blood cells, disorders of blood clotting, toxic forms of hepatitis, and skin and mucous membrane lesions. 

Vitamin K helps prevent skin and mucus membrane lesions. ... 

Skin and mucous membrane lesions are caused by deficiency of riboflavin and pyridoxine, not of vitamin K. 

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