Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Preparing oxygen-containing organic compound
Reexamination Certificate
1997-11-06
2001-01-09
Saucier, Sandra E. (Department: 1651)
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Preparing oxygen-containing organic compound
C435S252000, C436S071000
Reexamination Certificate
active
06171830
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the isolation and purification of lipid cell-wall components originating from bacteria assigned to the genera Mycobacterium, Corynebacterium, Nocardia or Rhodococcus, of which the most ubiquitous and the most important from a human health point of view is the genus Mycobacterium.
The genus Mycobacterium comprises a large number of both saprophytic and pathogenic species. The best known members of the genus,
M. tuberculosis
and
M. leprae,
are the causative agents of tuberculosis and leprosy, respectively, both among the most serious diseases occurring in man.
Tuberculosis: Current status
Tuberculosis is considered to be the major communicable disease throughout most of the world. Despite great advances in medical science and a range of effective drugs, which for some time created the impression that the disease had been conquered, and despite organised international efforts, tuberculosis remains a world health problem of staggering proportions: approximately one third of the world's population is infected with
M. tuberculosis
(Fauci, 1995), more than 8 million new cases world-wide and more than 3 million deaths in the year 1990 alone were reported (Snider, 1994). Predictions made by the World Health Organisation indicate that by the year 2000 the annual figures will grow to 10,2 million new cases and 3,5 million deaths, with Asia and sub-Saharan Africa being the most affected continents (De Cock et al., 1992; Dolin, Raviglione and Kochi, 1994; Raviglione, Snider and Kochi, 1995; Wilkinson and de Cock, 1996). According to the recently released “WHO Report on the Tuberculosis Epidemic, 1995” the figures anticipated for the next decade are even more alarming: 300 million new infections and 30 million deaths (Holler, 1995). In effect, tuberculosis was declared in 1993 by WHO to be a global public health emergency (Bloomfield, 1995; Wilkinson and de Cock, 1996).
The major reasons for this dramatic comeback and the unabated spread of tuberculosis can be identified as:
1) Insufficient protection offered by the world-wide vaccination programme based on the use of BCG*)
*) BCG: (Bacillus of Calmette and Guerin) Calmette and Guerin attenuated a strain of
M. bovis
by passing it 231 times over a period of 13 years through a medium containing glycerine and oxbile.
2) Problems associated with the detection of tuberculosis
3) Problems associated with treatment of tuberculosis and the occurrence of multi-drug resistant strains of
M. tuberculosis
4) Interaction with HIV infection
5) Socio-economic aspects
1. Insufficient Protection Offered By The World-Wide Vaccination Programme Based On BCG
Attempts to prevent the spread of tuberculosis by inducing resistance to the infection with
M. tuberculosis
were initiated at the beginning of this century, using vaccination with BCG. On the basis of a number of controlled studies it was established that the protective efficacy obtained in vaccination with BCG varied between 0 to 80% (Snider, 1994; Hershfield, 1995) and, on the basis of the analysis of the published literature, the BCG vaccination was found to be roughly 50% effective (Colditz et al., 1994; O'Brien, 1995). A number of hypotheses/explanations for this unsatisfactory situation have been put forward (Fine, 1994). The most important are:
i) Variations between BCG vaccines, which could be caused by strains variation or by differences between manufacturing processes;
ii) Differences in pathogenesis of
M. tuberculosis;
iii) Differences in the exposure to the environmental mycobacteria—the environmental mycobacteria may act antagonistically or synergistically with BCG;
iv) Genetic differences between population groups subjected to vaccination with BCG;
v) Differences in nutrition and exposure to sunlight between various population groups;
vi) Differences between designs of various studies;
vii) Inadequacies of the criteria used for the evaluation of protective action of vaccination with BCG.
2. Problems Associated With The Detection Of Tuberculosis
The accurate and timely detection of tuberculosis and related mycobacterial diseases is one of the important requirements for the development of a more successful global strategy to combat these diseases.
Traditional laboratory detection methods have major disadvantages of either not being capable of distinguishing between live and dead bacilli (the quick and simple Ziehl-Neelsen staining) or, if these methods confirm the presence of the live bacilli (direct cultivation), a number of weeks is required before the laboratory tests are completed. This in turn, may delay the commencement of treatment and may lead to further spread of the disease.
Although recently developed molecular approaches to the diagnosis of tuberculosis (Godfrey-Faussett, 1994; Richeldi, Barnini and Saltini, 1995; Bloomfield, 1995; Vlaspolder, Singer and Roggeveen, 1995) resulted in the introduction of these rapid and sensitive detection tools by advanced laboratories in the developed countries, they are expensive and require specially trained personnel. For these reasons they are not suitable for screening/detection of tuberculosis in resource-poor, TB-endemic regions, already overburdened with the cost of controlling the disease (O'Brien, 1995; Voelker, 1995).
A similar situation exists in the field of rapid drug sensitivity testing (Schaberg et al., 1995; Pretorius et al., 1996) and rapid culturing of Mycobacterium (Bloomfield, 1995). The significant advances in these areas cannot be utilised, for financial reasons, in the countries most affected by the tuberculosis pandemic.
3. Problems Associated With Treatment Of Tuberculosis And The Occurrence Of Multi-Drug Resistant Strains Of
M. tuberculosis
The development of effective chemotherapy for tuberculosis made the treatment of infected persons possible, thus preventing the full development of the disease. Although the anti-tuberculosis drugs with proven bacterial action (rifampicin, isoniazid and pyrazinamide) as well as the ones with bacteriostatic or resistance-preventing properties (streptomycin sulphate, ethambutol and thiacetazone) are available (Weil, 1994), worldwide success in combating the disease has not been achieved so far due to two main factors: patients' non-compliance with the prescribed regimen and financial limitations existing in developing countries.
The impact of the isoniazid preventative therapy on the control of tuberculosis in developing countries is uncertain. This approach, although widely practiced in North America, has two major disadvantages. Firstly, it may have to given for the duration of the TB sufferers' life and, secondly, its cost, i.e. US$18 per patient per 6-month course may be prohibitive, particularly in the most affected areas where an amount of US$4 per patient per year is available for total health care (O'Brien, 1995).
The interrupted and/or uncompleted treatment, apart from the detrimental effects on the individual concerned, has contributed to the emergence and spread of multi-drug resistant strains of
M. tuberculosis,
which further complicate the overall situation (Beyers et al., 1996). The recent WHO estimates indicate that 50 million people worldwide may already be carrying strains of
M. tuberculosis
resistant to one or more of the most common anti-TB drugs. It was established already in 1991, that one third of all TB patients in New York were resistant to at least one drug and almost 20% were resistant to rifampicin and isoniazid combined (Henderson 1995).
4. Interaction With HIV Infection
The close association documented between tuberculosis and HIV infection as well as the frequently concomitant presence of both these diseases add gravity to the situation (Torres et al., 1990; De Cock, 1994; Cantwell and Binkin, 1994; Murray, 1994; Antonucci et al.. 1995; Mofeson et al., 1995; Davies, Wilkinson and Colvin, 1996; Wilkinson and Moore, 1996). The number of people who develop tuberculosis in Asia because of the parallel infection with the HIV is expected to increase seven-fold th
Adcock Ingram Limited
Afremova Vera
Ladas & Parry
Saucier Sandra E.
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