A decrease in drug resistance levels of the HIV epidemic can be bad news

Transient decreases in the proportion of individuals newly infected with an HIV-resistant virus (primary resistance) are documented for several cities of North America, including San Francisco. Using a staged SI deterministic model, we identified three potential causes consistent with the history of the epidemic: (1) increase in risky behaviour, (2) reduction in the proportion of HIV-acutely infected individuals undergoing treatment, and (3) replacement of mono-and dual-drug therapies with triple-drug therapies. Although observed patterns resemble scenario 1 most closely, these explanations are not mutually exclusive and may have contributed synergistically to the decline. Under scenario 1 the counterintuitive situation arises where, although the proportion of primary resistance cases decreases transiently, the epidemic worsens because the actual numbers of infected individuals and of drug resistance carriers increases. Our results call for improved efforts to control the epidemic in developed nations, and highlight the usefulness of drug resistant strains as epidemiological markers. In memory of Eran Karmon, who passed away on March 5, 2003     

Megakaryocytic features useful for the diagnosis of myeloproliferative disorders can be obtained by a novel unsupervised software analysis

An unsupervised method for megakaryocyte detection and analysis is proposed, in order to validate supplementary tools which can be of help in supporting the pathologist in the classification of Philadelphia negative chronic myeloproliferative disorders with thrombocytosis. The experiment was conducted on high power magnification photomicrographs taken from hematoxylin-and-eosin 3 micrometer thick sections of formalin fixed, paraffin embedded bone marrow biopsies from patients with reactive thrombocytosis or chronic myeloproliferative disorders. Each megakaryocyte has been isolated in the photos through an image segmentation process, mainly based on mathematical morphology and wavelet analysis. A set of features (e.g. area, perimeter and fractal dimension of the cell and its nucleus, shape complexity via elliptic Fourier transform, and so on) is used to characterize the disorders and discriminate between essential thrombocythemia and idiopathic myelofibrosis. Features related to the general contour of the cell like cytoplasmic area and perimeter are good markers in distinguishing between normal or reactive and pathologic megakaryocytes while nuclear features and global circularity are helpful in the differential diagnosis between ET and prefibrotic IMF. The method proposed should be considered as a fast preprocessing tool for the diagnostic phase and its use can be extended to solve different object recognition problems.     

The prevention of HIV infection and STDs among injection drug addicts in Ukraine

In 1996-1998 joint pilot Projects of the National Committee and the UNAIDS Program were carried out in 10 Ukrainian cities. The behavior determinants contributing to the spread of HIV infection, common for all regions under study, were determined. They were linked with the injections of narcotic drugs, sexual behavior and the level of knowledge on the infection. The effectiveness of the projects was due to the 80% coverage of those drug addicts who could not be reached by common narcotic drug services; to the use of individual syringes (increased from 43% to 95%); to a decrease in the sale of ready-made drugs in used syringes to 14%; to an increase in the index of the return of used syringes; to an increase in the proportion of persons constantly using condoms (58%); etc. Still the situation was found to give no grounds for optimism, and the conclusion was made that the strategy of "decreasing the harm" must become the policy and strategy of the public health system.     

The receptor specificity of bacteriophages can be determined by a tail fiber modifying protein.

T-Even type bacteriophages recognize their cellular receptors with the distal ends of their long tail fibers. The distal part of these fibers consists of a dimer of gene product (gp) 37. The assembly of this gp to a functional dimer requires the action of two other proteins, gp57 and gp38. Genes (g) 38 have been cloned from five T-even type phages which use the Escherichia coli outer membrane protein OmpA as a receptor. The phages used differ in their ability to infect a series of ompA mutants producing altered OmpA proteins, i.e., each phage has a specific host range for these mutants. The cloned genes 38 complemented g38 amber mutants of phage T2, which uses the outer membrane protein OmpF as a receptor. The complemented phages had become phenotypically OmpA-dependent and, with one exception, OmpF-independent, but regained the host range of T2 upon growth in a host lacking the cloned g38. The host range of the complemented phages, as determined on the ompA mutants, was identical to, similar to, or different from that of the phage, from which the cloned g38 originated. The results presented show that gp38 from one phage can phenotypically 'imprint', in a finely-tuned manner, a host range onto gp37 of another phage with a different host specificity. In view of the extreme diversity of host ranges observed, it is suggested that gp38 of T2 and of the OmpA-specific phages may remain attached to gp37 in the phage particle and in cooperation with gp37 determine the host range.     

A vector that replicates as a plasmid and can be efficiently selected in B-lymphoblasts transformed by Epstein-Barr virus.

Epstein-Barr virus (EBV) transforms human B-lymphocytes into proliferating blasts which are efficiently established into cell lines. The viral DNA in these cell lines is usually present as complete, unintegrated plasmid molecules. A cis-acting element of EBV, oriP, permits plasmid maintenance in adherent cells that carry EBV DNA. We constructed a vector, pHEBo, that carries oriP and showed that it is also efficiently maintained as a plasmid when introduced into EBV-transformed B-lymphoblasts. The pHEBo vector carries the coding sequences for the hph gene from Escherichia coli such that it can be expressed in mammalian cells and confers resistance to the antibiotic hygromycin B. Hygromycin B kills EBV-transformed lymphoblasts at concentrations of 50 to 300 micrograms/ml. The combination of oriP plus the expressed hph gene makes pHEBo useful for the stable introduction of genes on plasmids into EBV-transformed lymphoblasts. Because pHEBo is derived from the plasmid pBR322 it can be easily isolated from lymphoblasts by reintroduction into E. coli.     

The hepatic PP1 glycogen-targeting subunit interaction with phosphorylase a can be blocked by C-terminal tyrosine deletion or an indole drug

The inhibition of hepatic glycogen-associated protein phosphatase-1 (PP1-G(L)) by glycogen phosphorylase a prevents the dephosphorylation and activation of glycogen synthase, suppressing glycogen synthesis when glycogenolysis is activated. Here, we show that a peptide ((280)LGPYY(284)) comprising the last five amino acids of G(L) retains high-affinity interaction with phosphorylase a and that the two tyrosines play crucial roles. Tyr284 deletion abolishes binding of phosphorylase a to G(L) and replacement by phenylalanine is insufficient to restore high-affinity binding. We show that a phosphorylase inhibitor blocks the interaction of phosphorylase a with the G(L) C-terminus, suggesting that the latter interaction could be targeted to develop an anti-diabetic drug.     

Outbreak of HIV infection in a Scottish prison.

OBJECTIVE--To investigate the possible spread of HIV infection and its route of transmission among prison inmates. DESIGN--In response to an outbreak of acute clinical hepatitis B and two seroconversions to HIV infection, counselling and testing for HIV were offered to all inmates over a two week period in July 1993. Information was sought about drug injecting, sexual behaviour, and previous HIV testing. SETTING--HM Prison Glenochil in Scotland. SUBJECTS--Adult male prisoners. MAIN OUTCOME MEASURES--Uptake of HIV counselling and testing; occurrence and mode of HIV transmission within the prison. RESULTS--Of a total 378 inmates, 227 (60%) were counselled and 162 (43%) tested for HIV. Twelve (7%) of those tested were positive for antibody to HIV. One third (76) of those counselled had injected drugs at some time, of whom 33 (43%) had injected in Glenochil; all 12 seropositive men belonged to this latter group. Thirty two of these 33 had shared needles and syringes in the prison. A further two inmates who injected in the prison were diagnosed as positive for HIV two months previously. Evidence based on sequential results and time of entry into prison indicated that eight transmissions definitely occurred within prison in the first half of 1993. CONCLUSION--This is the first report of an outbreak of HIV infection occurring within a prison. Restricted access to injecting equipment resulted in random sharing and placed injectors at high risk of becoming infected with HIV. Measures to prevent further spread of infection among prison injectors are urgently required.     

Helper-dependent vs. helper-independent CTL responses in HIV infection: implications for drug therapy and resistance.

Clinical data from HIV-infected patients, as well as theoretical studies, suggest that CTL responses in the presence and absence of CD4 cell help are qualitatively different. In the presence of help, CTL responses are maintained despite very low antigenic loads and control the infection in the long term. In the absence of specific helper cell responses, CTL require high antigenic loads to be maintained, are short lived at low levels of antigen, and do not control the infection in the long term. This paper describes mathematical models analysing the dynamics of helper-dependent and helper-independent CTL in HIV infection with special focus on the dynamics during drug therapy in chronic infection. Theory suggests that a fast rate of virus spread results in high degrees of helper cell impairment which promotes the development of helper-independent CTL responses and compromised immunological control. In agreement with clinical findings, the model suggests that upon start of therapy, there is a transient increase in the level of CTL, followed by a decline to low levels once virus load has been significantly suppressed. According to the model, the presence of helper-independent CTL can promote the establishment of a helper-dependent memory response. Interestingly, this gives rise to the prediction that a relatively early stop of therapy, before the level of CTL has fallen below a threshold, can promote improved immunological control. Issues concerning the timing and duration of treatment are discussed. The CTL kinetics during drug therapy also provide new insights into the principles underlying the emergence of drug-resistant strains during the course of treatment.     

Docking analysis insights quercetin can be a non-antibiotic adjuvant by inhibiting Mmr drug efflux pump in Mycobacterium sp. and its homologue EmrE in Escherichia coli

Drug efflux pumps (EP) like Mmr in Mycobacterium transported drugs out of cell, a main reason for drug resistance developing in Mycobacterium tuberculosis. In this in silico study, mainly analysed EP inhibitory potential of a plant-derived flavonoid, quercetin, through docking analysis. Mmr present in Mycobacterium smegmatis and M. tuberculosis, and its homologue EmrE of Escherichia coli was used. Initially, homology modelling of EP monomers and dimers constructed from M. smegmatis, M. tuberculosis and E. coli; the stabilities of models were analysed from Ramachandran plots prepared in PROCHECK. Docking analysis of quercetin with EP protein showed that in all three organisms, the residues for function and stability are important and quercetin had best interactions comparing to compounds such as, verapamil, reserpine, chlorpromazine, Carbonyl Cyanide m- Chloro Phenylhydrazone. Molecular dynamics and simulation studies showed that during the entire course of simulation quercetin-Mmr complex were stable. It insights quercetin can act as a non-antibiotic adjuvant for treatment of tuberculosis by bring down the efflux of drug from bacteria.