"Review: Application of Bioequivalence Testing of Medicines in Peru"

"This is a review of the current status of drug bioequivalence studies in Peru. A bibliographic search was conducted in PubMed (Medline database) for bioequivalence studies in Peru. Generic drugs constitute the basis of pharmacological requests in health care systems in Latin American countries. Peru has enacted laws and regulations that require bioequivalence studies of high health risk drugs and exemptions, based on international legislation, to be conducted in research centers accredited by the authority of Health. There is a list of 19 drugs that must demonstrate their therapeutic equivalence through in vivo or in vitro studies, of which 13 have shown bioequivalence in vivo, and 8 of those have shown bioequivalence in vitro. There is a challenge for health authorities to enforce the current legislation and an even greater challenge for pharmaceutical laboratories to demonstrate bioequivalence of multi-source drugs with the reference drug.

Serum albumin and osmolality inhibit Bdellovibrio bacteriovorus predation in human serum

We evaluated the bactericidal activity of Bdellovibrio bacteriovorus, strain HD100, within blood sera against bacterial strains commonly associated with bacteremic infections, including E. coli, Klebsiella pneumoniae and Salmonella enterica. Tests show that B. bacteriovorus HD100 is not susceptible to serum complement or its bactericidal activity. After a two hour exposure to human sera, the prey populations decreased 15- to 7,300-fold due to the serum complement activity while, in contrast, the B. bacteriovorus HD100 population showed a loss of only 33%. Dot blot analyses showed that this is not due to the absence of antibodies against this predator. Predation in human serum was inhibited, though, by both the osmolality and serum albumin. The activity of B. bacteriovorus HD100 showed a sharp transition between 200 and 250 mOsm/kg, and was progressively reduced as the osmolality increased. Serum albumin also acted to inhibit predation by binding to and coating the predatory cells. This was confirmed via dot blot analyses and confocal microscopy. The results from both the osmolality and serum albumin tests were incorporated into a numerical model describing bacterial predation of pathogens. In conclusion, both of these factors inhibit predation and, as such, they limit its effectiveness against pathogenic prey located within sera

Single-molecule kinetics of pore assembly by the membrane attack complex

The membrane attack complex (MAC) is a hetero-oligomeric protein assembly that kills pathogens by perforating their cell envelopes. The MAC is formed by sequential assembly of soluble complement proteins C5b, C6, C7, C8 and C9, but little is known about the rate-limiting steps in this process. Here, we use rapid atomic force microscopy (AFM) imaging to show that MAC proteins oligomerize within the membrane, unlike structurally homologous bacterial pore-forming toxins. C5b-7 interacts with the lipid bilayer prior to recruiting C8. We discover that incorporation of the first C9 is the kinetic bottleneck of MAC formation, after which rapid C9 oligomerization completes the pore. This defines the kinetic basis for MAC assembly and provides insight into how human cells are protected from bystander damage by the cell surface receptor CD59, which is offered a maximum temporal window to halt the assembly at the point of C9 insertion

Gene therapy for muscular dystrophy - Early experiments with liposome-mediated gene transfer

Duchenne muscular dystrophy is a lethal X-linked disorder in which muscle degeneration results in confinement to a wheelchair by age 12 years and death from respiratory failure by age 20 years. Gene therapy for this disorder poses unique challenges, related to the enormous size of the gene, and to the difficulty ofdelivering a functional gene to the millions of muscle fibers through-out the body. Adenoviral vectors are limited in their DNA capacity precluding their use to deliver an intact dystrophin gene cDNA, and the vectors themselves elicit an immune response that will further limit their use. Cationic liposomes provide a means to transfect cells bothex viva and in vivo. In this study we evaluated the use of a polycationic liposome formulation in delivering areporter gene in cultured muscle cells and designed a new procedure to enhance transfection efficiency of cationic liposomes, based on the precondensation of plasmid DNA with polylysine

Clusterin, the human apolipoprotein and complement inhibitor, binds to complement C7, C8 beta, and the b domain of C9

Clusterin is a heterodimeric multifunctional protein expressed in a variety of tissues and cells. It forms high density lipid complexes in plasma and participates in the control of the lytic activity of the late complement complex (TCC, C5b-9). Together with vitronectin, clusterin binds to the nascent amphiphilic C5b-9 complex, rendering it water soluble and lytically inactive. To define the interactions that underlie the complement-inhibitory function of clusterin, we have examined the binding interactions between [125I]clusterin and the isolated components of the complex, C5b-6, C7, C8, and C9 and vitronectin. By using ligand blotting in the presence of Tween, specific binding of the labeled clusterin with C7, the beta-subunit of C8 and C9 was detected. Binding to C9 was competed by polymerized C9, but not by C8, C7, C6, and CD59, suggesting that the conformational change occurring during the hydrophilic-amphiphilic transition of C9 exposes the interaction site for clusterin. When thrombin-treated C9 was analyzed, clusterin was found to recognize the C9b fragment containing the hydrophobic membrane interaction segment. Both subunits of clusterin interact with C9 and are similarly potent in inhibiting C5b-9-mediated hemolysis and Zn+(+)-induced C9 polymerization. These results show that clusterin exerts its inhibitory effect by interacting with a structural motif common to C7, C8 alpha, and C9b

Gene transfer mediated by fusion protein hemagglutinin reconstituted in cationic lipid vesicles

Hemagglutinin, the membrane fusion protein of influenza virus,is known to mediate a low-pH-dependent fusion reaction between the viral envelope and the limiting membrane of the endosomal cell compartment following cellular uptake of the virus particles by receptor-mediated endocytosis. Here we exploited this activity of hemagglutinin to achieve efficient gene delivery to cultured cells. Hemagglutinin was reconstituted in the presence of the monocationic lipid dioleoyldimethylammonium chloride (DODAC) to permit plasmid binding to the virosome surface. Virosomes with 30 mol% DODAC exhibited a distinct binding capacity plasmid without causing aggregation. The virosome an activity was not affected by the cationic lipid DODAC demonstrated by low-phr-dependent lipid mixing with erythrocyte ghosts. Efficient cell transfection of BHK-21 cells was observed with virosomes containing 30 mol% DODAC and plasmid encoding for p-galactosidase (pCMV; beta-gal) associated to their surface. The transfection activity observed was dependent on the functional activity of hemagglutinin. Contrary to DNA/cationic lipid complexes the transfection was not dependent on the cationic lipid to DNA charge ratio. Importantly, transfection of BHK-21 cells with pCMV beta-gal by DODAC-containing virosomes did not show any significant signs of cytotoxicity that is commonly observed with DNA/cationic lipid complexes. Together with the high levels of expression of the transgene this highlights the potential of DODAC-containing virosomes as a novel approach in nonviral gene transfer