- Email: [email protected]
PEPTIC ULCERATION
280
A, Webb OF, Thonnard JE, Sayler GS. Specific and quantitative of napthaline and salicylate by using a bioluminescent catabolic reporter bacterium. Appl Env Microbiol 1992; 58: 1839-46.
8. Heitzer
assessment
9. Moelders H. World Patent Index accession number 90-239981/32 Patent CC number DE 3902982.ICM C12Q001-02 1990. 10. Guzzo A, Diorio C, DuBow MS. Transcription of the Escherichia colifliC gene is regulated by metal ions. Appl Environ Microbiol 1991; 57: 2255-59.
monitoring of previously.1
outcome,
which
has
been
criticised
David
Sharp
1. Editorial. Pandolfi’s box: research in Europe. Lancet 1992; 339: 1516. 2. Biomed Hlh Res Newsl 1992; 3 (no 3, December). Published free of charge by the Commission of the European Communities, DG XII-E-4,
Medical Research Division,
rue
de la Loi 200, B-1049 Brussels,
Belgium.
EUROPEAN COMMUNITY
Euro grants and
procedures
PEPTIC ULCERATION
The European Community’s capacity for wasting money
levied from the peoples of twelve nations knows no bounds and few EC critics will have bothered to look closely at the research budget, within which lies a small sum for biomedical projects.1 Scientists have been concerned, however. The latest issue of the newsletter of the EC biomedical and health research programme (BIOMED)2 will therefore be of interest not just because of the list of who has got what but also because of how the second round of applications is to be handled. Topic Project leads Projects Country 12 8 Drugs Belgium Risk factors Biomedical technology Health services
5 17 9
AIDS S Cancer Cardiovascular disease
14 18 13 7 15
Denmark France
Germany Greece
Psychiatry, neurology Age, ageing* Ethics *
Broad category, renal disease.
Italy Netherlands
Portugal Spain UK
5 17 13 3 13 17 2 2 30
8
including diabetes, intrauterine growth retardation, and
Unless you are into human genome work it is still not too late to apply. Feb 26 is the deadline for proposals for "concerted actions", in which the EC lubricates collaborative research with a European dimension without directly paying for it. Anonymous peer review from three or more scientists comes first, grading your idea A plus to C. Discipline-oriented groups of one expert from each member state, supplemented if need be, will then attempt an overall scientific ranking. By the end of May, it is hoped, you will have been judged 1 to 4 on the relevance of the proposal to EC target areas and on the European dimension. If you are lucky you will be shortlisted by another committee (CANMED), and from July, if the EC Commission approves, you might even get some money. The a priori probability of success is not high if previous experience is anything to go
by.
.
The University of Newcastle upon Tyne reckons that it has "scooped the pool" in the recent handouts. Four major research grants totalling over a million ecu ([1.25 million) would be a significant boost to medical research in any university, and one to be pleased with too since fierce competition has left 95% or so of applicants with empty pockets. But the spirit of BIOMED is cooperation. Newcastle has four new project leaders and in those four projects up to thirteen other countries (BIOMED is generous about borders) are participating. The EC tactfully leaves national failure rates out of its information package and a country’s size and local research budget are not in the denominators, which is why the above national list is alphabetical rather than in league table form. It is to be hoped that the rethinking now on show will extend to the
H pylori-initiated ulcerogenesis: look to the host Let me be blunt: there are no distinct ulcerogenic strains of Helicobacter pylori. I realise this view is controversial, but such has been my belief for many years. I am not saying that H pylori is not a pathogen, the evidence for a causal role in 95% of duodenal ulcers being overwhelming. My claim is that all strains of H pylori have the ability to induce ulceration if other conditions are met. A study of the H pylori, status of three generations of an ulcer-prone family in Coventry, UK,l adds support to such a view. Investigation of nine family members, spanning three generations, for H pylori status showed eight to be positive for the bacterium and five to have duodenal ulcer disease. Using DNA fingerprinting, the researchers found that three family members harboured almost identical strains of H pylori but only two of these had ulcer disease. The remaining five individuals harboured distinct strains yet three of these had ulcers. Nwokolo et al concluded that the high proportion of ulcers in this family was not due to the sharing of a hypervirulent ulcerogenic strain. This report, apart from providing evidence of intrafamilial spread with one strain through three generations, also confirmed the considerable variation among strains of H pylori cultured from different persons. Other workers have studied hundreds of H pylori isolates from patients by means of a range of fingerprinting techniques including electrophoresis of endonuclease digests of chromosomal DNA, ribotyping, and polymerase chain reaction methods.2-4 All isolates were found to be different distinct clones unless they were taken from the same patient at different times or unless the epidemiological evidence accorded with intrafamilial spread or endoscopic transmission. Such extreme genomic heterogeneity is unusual among bacterial pathogens, in which specific virulent clones can normally be identified. For example, there are many Escherichia coli serotypes (genotypes) but only a few E coli clones cause extra-intestinal-tract infections and, in contrast to H pylori, the degree of chromosomal relatedness among pathogenic E coli is high.2 Often, specific virulence determinants are carried on extrachromosomal elements. One has to look to the epidemiology and ecology of H pylori infection for an explanation of the genomic heterogeneity of this bacterium. H pylori is an unusual pathogen in that it colonises gastric mucus, a very restricted niche in the host, and remains there for tens of years in the absence of competition from any other bacteria. Transmission of each strain from person to person generally occurs within families, mainly in childhood 5 However, the bacterium is relatively non-infectious and not easily transmitted. Thus, there is little competition among clones for selection of the fittest in an evolutionary sense.4 Since
281
Hpylori can integrate naked DNA from its environment (ie, transform) each clone could develop via successive genomic rearrangements in the natural gastric environment during long-term residence in the current and any previous human hosts. The DNA patterns of the same strain isolated over the three generations in the Coventry study accord with this hypothesis, and show a decreasing similarity over the generations studied. In this family, the percentage similarity between an isolate from an eighteen-year-old girl and that from her fifty-year-old mother was extremely close (92%). By contrast, when the isolate was compared with the strain isolated from her seventy-one-year-old grandmother the similarity was only 82%. Another consequence of the restricted niche of H pylori is an extremely limited opportunity for acquisition from other bacteria of potential virulence genes encoded on extrachromosomal elements such as plasmids or transposons. In view of the observed genomic heterogeneity of H pylori, the Coventry data, and the lack of an obvious advantage of ulcerogenesis to a parasite so well adapted to the antral mucosa, I feel confident in concluding there are no distinct ulcerogenic strains of this gastroduodenal parasite. Rather than conducting exhaustive studies of isolates from ulcer patients compared with non-ulcer patients the research priority is surely to identify those host factors that allow changes in the mucosal environment caused by colonisation with any strain of H pylori to initiate ulceration in the duodenum but seldom in the gastric antrum.
Adrian Lee CU, Bickley J, Attard AR, et al. Evidence of clonal variants of Helicobacter pylori in three generations of a duodenal ulcer disease family. Gut 1992; 33: 1323-27. 2. Solnick J, Tompkins L. Helicobacter pylori and gastroduodenal disease: pathogenesis and the host-parasite interaction. Infect Agents Dis 1. Nwokolo
(in press). D. Genetics of Campylobacter and Helicobacter. Annu Rev Microbiol 1992; 46: 35-64. 4. Akopyanz N, Bukanov NO, Westblom UT, et al. DNA diversity among clinical isolates of Helicobacter pylori detected by PCR-based RAPD fingerprinting. Nucleic Acids Res 1992; 20: 5137-42. 5. Mitchell HM, Li YY, Hu PJ, et al. Epidemiology of Helicobacter pylori in southern China: identification of early childhood as the critical period for acquisition. J Infect Dis 1992; 166: 149-53. 3.
Taylor
MOLECULAR MEDICINE
Ageing, There
cancer, and mitochondrial deterioration are two
types of DNA in the human cell. One of
them, nuclear DNA, is the subject of vast research interest and "mapping the human genome" is a concept familiar even to the lay public. The other type of DNA is confmed to the mitochondria, has a different genetic code and structure, and its sequence was completely mapped some years ago. Several genetic disorders have been assigned to mitochondrial DNA and research has now shown that age-dependent changes in mitochondria may be associated with the process of human ageing. The idea that mitochondria are living fossil parasites within eukaryote cells has evolved as a general theory applicable to several intracellular organelles including cilia, nuclear DNA, and the nuclear spindle.1,2 As far as mitochondria are concerned, the concept is that primitive cells lacking respiratory organelles were parasitised by oxygen-using bacteria that conferred a selective evolutionary advantage. Host and bacterium subsequently
became interdependent and obligatorily symbiotic. During this process some of the bacterial DNA became transferred to the host genome while some remained in the mitochondria. There are many arguments to support this thesis and some oddities of mitochondrial behaviour are difficult to explain in any other way--eg, their possession of circular (bacterial type) DNA, their ability to divide in the cell independent of cellular division, and the fact that mammalian mitochondria all come from the female gamete with none from the male gamete. The conditions that led to this symbiotic relationship differed from those that now prevail and consequently the role of mitochondria within eukaryote cells has changed. The original environment on the earth was "reducing" (ie, no free oxygen but numerous gases such as methane and ammonia) and so there was no need for primitive cells to develop enzyme systems capable of dealing with free oxygen. As photosynthetic activity increased, the atmosphere began to contain free oxygen, one of the most reactive and dangerous of substances. Free oxygen would be lethal to cells that lacked detoxification mechanisms and the pre-eukaryotes would have been doomed had they not been parasitised by bacteria that had developed the requisite coping mechanism. The biological strategy adopted by the bacteria was to release the oxidative energy of oxygen by small quanta donated to suitable receptors, the final products being carbon dioxide and water. Thus the conditions were in place for this process to be linked to the production of energy storage molecules such as ATP. This mechanism, whereby a process or structure is available before it becomes attached to its eventual use, is called
"pre-adaptation" by evolutionary biologists. What we see in the mitochondria now is the end result of safe detoxification of oxygen; and the secondary effect of this process, respiration, has become the main support of most living systems. However, the primordial mitochondrial function remains-that of removing toxic oxygen and its even more toxic products such as oxygen-derived free radicals. There is now evidence that ageing in higher animals may be due to accumulated mutations in the mitochondrial genome that reduce their function as respiratory units, and that once a mitochondrial mutation appears in a cell it seems to overgrow the "wild type" mitochondria.3 From the early days of cancer research there has been a feeling that oxidative metabolism is in some way abnormal in malignant cells. Even though the original concept, which featured a constitutive increase in glycolysis in all cancer cells, was shown to be untrue, many tumours with high glycolytic rates do have mitochondrial abnormalities. There remains a large body of evidence indicating mitochondrial involvement in cancer cells,4 and Sharp et al,s in a study of breast cancer, lately showed that subunit 2 of cytochrome c oxidase is significantly over-expressed in carcinoma cells compared with stromal cells, normal tissue, and fibroadenoma tissue. There is also indirect evidence that antioxidants may reduce mutationally related events such as the development of malignant disorders.6 After putting these lines of thought together, we conclude that mitochondrial activities afford protection against both sets of age-related diseases (ageing and cancer) and, conversely, mitochondrial instability may increase the risk. There is also evidence that some tumour behaviour is modified by mitochondria and that tumours with a pronounced increase in mitochondrial numbers (oncocytomas) have a better prognosis that their non-oncocytic counterparts.7
A, Webb OF, Thonnard JE, Sayler GS. Specific and quantitative of napthaline and salicylate by using a bioluminescent catabolic reporter bacterium. Appl Env Microbiol 1992; 58: 1839-46.
8. Heitzer
assessment
9. Moelders H. World Patent Index accession number 90-239981/32 Patent CC number DE 3902982.ICM C12Q001-02 1990. 10. Guzzo A, Diorio C, DuBow MS. Transcription of the Escherichia colifliC gene is regulated by metal ions. Appl Environ Microbiol 1991; 57: 2255-59.
monitoring of previously.1
outcome,
which
has
been
criticised
David
Sharp
1. Editorial. Pandolfi’s box: research in Europe. Lancet 1992; 339: 1516. 2. Biomed Hlh Res Newsl 1992; 3 (no 3, December). Published free of charge by the Commission of the European Communities, DG XII-E-4,
Medical Research Division,
rue
de la Loi 200, B-1049 Brussels,
Belgium.
EUROPEAN COMMUNITY
Euro grants and
procedures
PEPTIC ULCERATION
The European Community’s capacity for wasting money
levied from the peoples of twelve nations knows no bounds and few EC critics will have bothered to look closely at the research budget, within which lies a small sum for biomedical projects.1 Scientists have been concerned, however. The latest issue of the newsletter of the EC biomedical and health research programme (BIOMED)2 will therefore be of interest not just because of the list of who has got what but also because of how the second round of applications is to be handled. Topic Project leads Projects Country 12 8 Drugs Belgium Risk factors Biomedical technology Health services
5 17 9
AIDS S Cancer Cardiovascular disease
14 18 13 7 15
Denmark France
Germany Greece
Psychiatry, neurology Age, ageing* Ethics *
Broad category, renal disease.
Italy Netherlands
Portugal Spain UK
5 17 13 3 13 17 2 2 30
8
including diabetes, intrauterine growth retardation, and
Unless you are into human genome work it is still not too late to apply. Feb 26 is the deadline for proposals for "concerted actions", in which the EC lubricates collaborative research with a European dimension without directly paying for it. Anonymous peer review from three or more scientists comes first, grading your idea A plus to C. Discipline-oriented groups of one expert from each member state, supplemented if need be, will then attempt an overall scientific ranking. By the end of May, it is hoped, you will have been judged 1 to 4 on the relevance of the proposal to EC target areas and on the European dimension. If you are lucky you will be shortlisted by another committee (CANMED), and from July, if the EC Commission approves, you might even get some money. The a priori probability of success is not high if previous experience is anything to go
by.
.
The University of Newcastle upon Tyne reckons that it has "scooped the pool" in the recent handouts. Four major research grants totalling over a million ecu ([1.25 million) would be a significant boost to medical research in any university, and one to be pleased with too since fierce competition has left 95% or so of applicants with empty pockets. But the spirit of BIOMED is cooperation. Newcastle has four new project leaders and in those four projects up to thirteen other countries (BIOMED is generous about borders) are participating. The EC tactfully leaves national failure rates out of its information package and a country’s size and local research budget are not in the denominators, which is why the above national list is alphabetical rather than in league table form. It is to be hoped that the rethinking now on show will extend to the
H pylori-initiated ulcerogenesis: look to the host Let me be blunt: there are no distinct ulcerogenic strains of Helicobacter pylori. I realise this view is controversial, but such has been my belief for many years. I am not saying that H pylori is not a pathogen, the evidence for a causal role in 95% of duodenal ulcers being overwhelming. My claim is that all strains of H pylori have the ability to induce ulceration if other conditions are met. A study of the H pylori, status of three generations of an ulcer-prone family in Coventry, UK,l adds support to such a view. Investigation of nine family members, spanning three generations, for H pylori status showed eight to be positive for the bacterium and five to have duodenal ulcer disease. Using DNA fingerprinting, the researchers found that three family members harboured almost identical strains of H pylori but only two of these had ulcer disease. The remaining five individuals harboured distinct strains yet three of these had ulcers. Nwokolo et al concluded that the high proportion of ulcers in this family was not due to the sharing of a hypervirulent ulcerogenic strain. This report, apart from providing evidence of intrafamilial spread with one strain through three generations, also confirmed the considerable variation among strains of H pylori cultured from different persons. Other workers have studied hundreds of H pylori isolates from patients by means of a range of fingerprinting techniques including electrophoresis of endonuclease digests of chromosomal DNA, ribotyping, and polymerase chain reaction methods.2-4 All isolates were found to be different distinct clones unless they were taken from the same patient at different times or unless the epidemiological evidence accorded with intrafamilial spread or endoscopic transmission. Such extreme genomic heterogeneity is unusual among bacterial pathogens, in which specific virulent clones can normally be identified. For example, there are many Escherichia coli serotypes (genotypes) but only a few E coli clones cause extra-intestinal-tract infections and, in contrast to H pylori, the degree of chromosomal relatedness among pathogenic E coli is high.2 Often, specific virulence determinants are carried on extrachromosomal elements. One has to look to the epidemiology and ecology of H pylori infection for an explanation of the genomic heterogeneity of this bacterium. H pylori is an unusual pathogen in that it colonises gastric mucus, a very restricted niche in the host, and remains there for tens of years in the absence of competition from any other bacteria. Transmission of each strain from person to person generally occurs within families, mainly in childhood 5 However, the bacterium is relatively non-infectious and not easily transmitted. Thus, there is little competition among clones for selection of the fittest in an evolutionary sense.4 Since
281
Hpylori can integrate naked DNA from its environment (ie, transform) each clone could develop via successive genomic rearrangements in the natural gastric environment during long-term residence in the current and any previous human hosts. The DNA patterns of the same strain isolated over the three generations in the Coventry study accord with this hypothesis, and show a decreasing similarity over the generations studied. In this family, the percentage similarity between an isolate from an eighteen-year-old girl and that from her fifty-year-old mother was extremely close (92%). By contrast, when the isolate was compared with the strain isolated from her seventy-one-year-old grandmother the similarity was only 82%. Another consequence of the restricted niche of H pylori is an extremely limited opportunity for acquisition from other bacteria of potential virulence genes encoded on extrachromosomal elements such as plasmids or transposons. In view of the observed genomic heterogeneity of H pylori, the Coventry data, and the lack of an obvious advantage of ulcerogenesis to a parasite so well adapted to the antral mucosa, I feel confident in concluding there are no distinct ulcerogenic strains of this gastroduodenal parasite. Rather than conducting exhaustive studies of isolates from ulcer patients compared with non-ulcer patients the research priority is surely to identify those host factors that allow changes in the mucosal environment caused by colonisation with any strain of H pylori to initiate ulceration in the duodenum but seldom in the gastric antrum.
Adrian Lee CU, Bickley J, Attard AR, et al. Evidence of clonal variants of Helicobacter pylori in three generations of a duodenal ulcer disease family. Gut 1992; 33: 1323-27. 2. Solnick J, Tompkins L. Helicobacter pylori and gastroduodenal disease: pathogenesis and the host-parasite interaction. Infect Agents Dis 1. Nwokolo
(in press). D. Genetics of Campylobacter and Helicobacter. Annu Rev Microbiol 1992; 46: 35-64. 4. Akopyanz N, Bukanov NO, Westblom UT, et al. DNA diversity among clinical isolates of Helicobacter pylori detected by PCR-based RAPD fingerprinting. Nucleic Acids Res 1992; 20: 5137-42. 5. Mitchell HM, Li YY, Hu PJ, et al. Epidemiology of Helicobacter pylori in southern China: identification of early childhood as the critical period for acquisition. J Infect Dis 1992; 166: 149-53. 3.
Taylor
MOLECULAR MEDICINE
Ageing, There
cancer, and mitochondrial deterioration are two
types of DNA in the human cell. One of
them, nuclear DNA, is the subject of vast research interest and "mapping the human genome" is a concept familiar even to the lay public. The other type of DNA is confmed to the mitochondria, has a different genetic code and structure, and its sequence was completely mapped some years ago. Several genetic disorders have been assigned to mitochondrial DNA and research has now shown that age-dependent changes in mitochondria may be associated with the process of human ageing. The idea that mitochondria are living fossil parasites within eukaryote cells has evolved as a general theory applicable to several intracellular organelles including cilia, nuclear DNA, and the nuclear spindle.1,2 As far as mitochondria are concerned, the concept is that primitive cells lacking respiratory organelles were parasitised by oxygen-using bacteria that conferred a selective evolutionary advantage. Host and bacterium subsequently
became interdependent and obligatorily symbiotic. During this process some of the bacterial DNA became transferred to the host genome while some remained in the mitochondria. There are many arguments to support this thesis and some oddities of mitochondrial behaviour are difficult to explain in any other way--eg, their possession of circular (bacterial type) DNA, their ability to divide in the cell independent of cellular division, and the fact that mammalian mitochondria all come from the female gamete with none from the male gamete. The conditions that led to this symbiotic relationship differed from those that now prevail and consequently the role of mitochondria within eukaryote cells has changed. The original environment on the earth was "reducing" (ie, no free oxygen but numerous gases such as methane and ammonia) and so there was no need for primitive cells to develop enzyme systems capable of dealing with free oxygen. As photosynthetic activity increased, the atmosphere began to contain free oxygen, one of the most reactive and dangerous of substances. Free oxygen would be lethal to cells that lacked detoxification mechanisms and the pre-eukaryotes would have been doomed had they not been parasitised by bacteria that had developed the requisite coping mechanism. The biological strategy adopted by the bacteria was to release the oxidative energy of oxygen by small quanta donated to suitable receptors, the final products being carbon dioxide and water. Thus the conditions were in place for this process to be linked to the production of energy storage molecules such as ATP. This mechanism, whereby a process or structure is available before it becomes attached to its eventual use, is called
"pre-adaptation" by evolutionary biologists. What we see in the mitochondria now is the end result of safe detoxification of oxygen; and the secondary effect of this process, respiration, has become the main support of most living systems. However, the primordial mitochondrial function remains-that of removing toxic oxygen and its even more toxic products such as oxygen-derived free radicals. There is now evidence that ageing in higher animals may be due to accumulated mutations in the mitochondrial genome that reduce their function as respiratory units, and that once a mitochondrial mutation appears in a cell it seems to overgrow the "wild type" mitochondria.3 From the early days of cancer research there has been a feeling that oxidative metabolism is in some way abnormal in malignant cells. Even though the original concept, which featured a constitutive increase in glycolysis in all cancer cells, was shown to be untrue, many tumours with high glycolytic rates do have mitochondrial abnormalities. There remains a large body of evidence indicating mitochondrial involvement in cancer cells,4 and Sharp et al,s in a study of breast cancer, lately showed that subunit 2 of cytochrome c oxidase is significantly over-expressed in carcinoma cells compared with stromal cells, normal tissue, and fibroadenoma tissue. There is also indirect evidence that antioxidants may reduce mutationally related events such as the development of malignant disorders.6 After putting these lines of thought together, we conclude that mitochondrial activities afford protection against both sets of age-related diseases (ageing and cancer) and, conversely, mitochondrial instability may increase the risk. There is also evidence that some tumour behaviour is modified by mitochondria and that tumours with a pronounced increase in mitochondrial numbers (oncocytomas) have a better prognosis that their non-oncocytic counterparts.7