HIV 's ability to infect human cells may be vastly enhanced by the presence of a chemical that occurs naturally in semen , research suggests.
The discovery could offer a new target for preventing the spread of AIDS , for example, by incorporating potential inhibitors of the semen chemical into the powerful new microbicides currently being developed to halt the spread of the virus
While searching for chemicals in semen that could block HIV transmission, an international team led by Frank Kirchhoff at the University Clinic of Ulm in Germany, was instead surprised to find that the naturally occurring chemical prostatic acidic phosphatase (PAP) promoted HIV infection.
Closer inspection revealed that PAP formed tiny fibres known as amyloid fibrils that were able to "ferry" the virus into the immune cells that it preys upon.
"Most enhancers have maybe a two or three-fold effect, but here the effect was amazing – more than 50-fold and, under certain conditions, more than 100,000-fold," says Kirchhoff. "At first, I didn't believe it, but we ran the experiment over and over, always with the same result."
Virus 'ferry'
"The fibrils act like a ferry. They pick the viruses up and then bring them to the cell," adds fellow researcher Wolf-Georg Forssmann at the Hannover Medical School, also in Germany.
Significantly, their laboratory tests showed that the fibrils' ability to assist infection was greatest when the levels of infectious virus were low – resembling the conditions in which sexual HIV-1 transmission usually occurs.
HIV-1, the most common and virulent form of the virus that causes AIDS, has infected about 60 million people and caused over 20 million deaths. Globally, most infections result from genital exposure to the semen of HIV-positive men.
Women who acquire HIV-1 through vaginal intercourse constitute almost 60% of new infections in Africa. Therefore the latest findings could have enormous clinical and public health implications, particularly for regions such as Sub-Saharan Africa where AIDS has caused devastation.
'Important discovery'
Kirchhoff says he hoped that agents that blocked prostatic acidic phosphatase might be developed and added to vaginal microbicides that women could use to protect themselves from infection. He also believes the discovery could have important implications for researchers hunting an elusive HIV vaccine.
Jonathan Weber, an eminent HIV researcher at Imperial College London , UK, was positive about the findings. "Kirchhoff is a great scientist and this is meticulous work," he says.
But Weber says there is much work to be done before new microbicides could be produced as a result of the findings. He notes, too, that the ability of HIV-positive women to infect men suggested that the presence of seminal PAP fibrils was not always required for infection to occur.
He adds, however: "This work is exciting because it opens up whole new avenues of prevention. It really does suggest entirely new directions of research, and like many of the really important discoveries it was completely unexpected."
Journal reference: Cell (DOI: 10.1016/j.cell.2007.10.014)
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Monday
Preliminary investigations on the standardization and quality control for the determination of acid phosphatase activity in seminal plasma
Background
The determination of Acid Phosphatase ACP in seminal plasma was considered as an appropriate biochemical marker to evaluate prostate function , as recommended by the WHO manual. However, few reports on the standardization and quality control for the determination of biochemical markers in seminal plasma have been documented.
Methods
Two frozen samples of seminal plasma with or without phenylmethylsulfonyl fluoride were determined for their Acid Phosphatase (ACP) levels. The Acid Phosphatase level and sperm concentration of each of 72 samples of seminal plasma obtained at 1000×g for 10 min or 3000×g for 15 min centrifugation were assayed. Acid Phosphatase activity in 10 samples of seminal plasma was measured immediately or standing for 30 min after dilution. The ACP levels in seminal plasma with or without chymotrypsin were also assayed.
Results
There was no significant difference of ACP levels (P = 0.166) but of sperm concentrations (P = 0.000) in seminal plasma obtained by centrifugation at different velocity. ACP activities in seminal plasma measured when standing for 30 min after dilution were significantly lower than those measured immediately after dilution (P = 0.001). Both chymotrypsin and freezing–thawing had no apparent effect on the determination of ACP in seminal plasma.
Conclusion
The results indicated that standing time after dilution and centrifugation velocity should be standardized, and frozen seminal plasma could serve as the quality control products for the determination of ACP activity among different laboratories.
Department of Reproduction and Genetics, Jinling Hospital, School of Medicine, Nanjing University , Nanjing, Jiangsu 210002, China
Clinica Chimica Acta
Volume 375, Issues 1-2, January 2007, Pages 76-81
The determination of Acid Phosphatase ACP in seminal plasma was considered as an appropriate biochemical marker to evaluate prostate function , as recommended by the WHO manual. However, few reports on the standardization and quality control for the determination of biochemical markers in seminal plasma have been documented.
Methods
Two frozen samples of seminal plasma with or without phenylmethylsulfonyl fluoride were determined for their Acid Phosphatase (ACP) levels. The Acid Phosphatase level and sperm concentration of each of 72 samples of seminal plasma obtained at 1000×g for 10 min or 3000×g for 15 min centrifugation were assayed. Acid Phosphatase activity in 10 samples of seminal plasma was measured immediately or standing for 30 min after dilution. The ACP levels in seminal plasma with or without chymotrypsin were also assayed.
Results
There was no significant difference of ACP levels (P = 0.166) but of sperm concentrations (P = 0.000) in seminal plasma obtained by centrifugation at different velocity. ACP activities in seminal plasma measured when standing for 30 min after dilution were significantly lower than those measured immediately after dilution (P = 0.001). Both chymotrypsin and freezing–thawing had no apparent effect on the determination of ACP in seminal plasma.
Conclusion
The results indicated that standing time after dilution and centrifugation velocity should be standardized, and frozen seminal plasma could serve as the quality control products for the determination of ACP activity among different laboratories.
Department of Reproduction and Genetics, Jinling Hospital, School of Medicine, Nanjing University , Nanjing, Jiangsu 210002, China
Clinica Chimica Acta
Volume 375, Issues 1-2, January 2007, Pages 76-81
Tuesday
Acid Phospatase
Acid phosphatase is a phosphatase, a type of enzyme, used to free attached phosphate groups from other molecules during digestion. Acid Phosphatase is basically a phospho homo esterase . Acid Phosphatase is stored in lysosomes and functions when these fuse with endosomes, which are acidified while they function; therefore, it has an acid pH optimum.
Different forms of acid phosphatase are found in different organs, and their serum levels are used as a diagnostic for disease in the corresponding organs. For example, elevated prostatic acid phosphatase levels may indicate the presence of prostate cancer.
Prostatic acid phosphatase (PAP) is an enzyme produced by the prostate. Acid phosphatase may be found in increased amounts in men who have prostate cancer or other diseases.
The highest levels of acid phosphatase are found in metastasized prostate cancer. Diseases of the bone, such as Paget's disease or hyperparathyroidism, diseases of blood cells, such as sickle-cell disease or multiple myeloma or lysosomal storage diseases, such as Gaucher's disease, will show moderately increased levels.
Different forms of acid phosphatase are found in different organs, and their serum levels are used as a diagnostic for disease in the corresponding organs. For example, elevated prostatic acid phosphatase levels may indicate the presence of prostate cancer.
Prostatic acid phosphatase (PAP) is an enzyme produced by the prostate. Acid phosphatase may be found in increased amounts in men who have prostate cancer or other diseases.
The highest levels of acid phosphatase are found in metastasized prostate cancer. Diseases of the bone, such as Paget's disease or hyperparathyroidism, diseases of blood cells, such as sickle-cell disease or multiple myeloma or lysosomal storage diseases, such as Gaucher's disease, will show moderately increased levels.
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