- Email: [email protected]
Therapy for priapism in sickle-cell anaemia improved
Hyaluronic acid binds malaria-infected red blood cells in placenta sion to hyaluronic acid, compared with only five of 14 isolates from the peripheral blood of pregnant women, and five of 15 from children. These results indicate that parasites able to alter the erythrocyte cell membrane in such a way that it sticks to hyaluronic acid may be prone to accumulation in the lining of the placental blood spaces where hyaluronic acid concentrations are high. In addition, results from flow-based assays indicate that the binding of parasiteinfected red blood cells to hyaluronic acid was strong enough for accumulation of erythrocytes only when blood flow was slow, suggesting that the unique low-pressure environment of the placenta encourages parasitic accumulation (Nat Med 2000; 6: 86–90). “These results change our understanding of the mechanisms that underlie placental infection”, says Beeson. Stephen Hoffman, director of the malaria programme at the Naval Medical Research Center (Rockville, MD, USA) agrees that “these exciting findings re-emphasise the complexity of P falciparum interactions with its human host”. But, he
warns, pure hyaluronic acid preparations are extremely difficult, if not impossible, to obtain without some chondroitin sulphate A contamination. Beeson counters that “a variety
Science Photo Library
revious studies have shown that red blood cells infected with malarial parasites can accumulate in the placenta by interacting with chondroitin sulphate A on the placental lining. Now, researchers have identified hyaluronic acid as a second major receptor in the same tissue. Researchers have puzzled for decades over how the malaria parasite Plasmodium falciparum accumulates in the placenta, putting millions of pregnant women and their babies at risk every year. According to lead author James Beeson (Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia), these new results suggest that “by sticking to certain glycosaminoglycans in the placental lining, P falciparum manages to replicate in blood spaces in the placenta whilst ‘hidden’ from the full force of the host’s immune system”. Beeson and colleagues compared 15 placental isolates of P falciparuminfected erythrocytes with several non-placental isolates obtained from donors in Malawi for their ability to adhere to immobilised, purified hyaluronic acid. 12 of the 15 placental isolates showed substantial adhe-
P
Fatally attracted to placental membrane
of observations indicate that the adhesion could not be explained by such contamination”. Nevertheless, Hoffman would like to see follow-up studies and concludes that “if the results can be substantiated independently, they could lead to a more realistic and sophisticated approach to developing therapies to prevent malaria during pregnancy”. Kathryn Senior
Therapy for priapism in sickle-cell anaemia improved
News in brief
A
Hepatic metastases Outcome at 2 years is improved by hepatic arterial infusion of floxuridine and dexamethasone after resection of colorectal liver metastases, report Nancy Kemeny (Memorial SloanKettering Cancer Center, New York, USA) and co-workers. Their results—presented at last year’s American Society of Clinical Oncology (see Lancet 1999; 353: 1771)—show that patients treated with systemic fluorouracil have a relative risk of death of 2·34 compared with those treated with arterial infusion plus systemic therapy (N Engl J Med 1999; 341: 2039–48).
study of the management of prolonged priapism in young patients with sickle-cell anaemia has shown that aspiration of the corpora cavernosa followed by irrigation with epinephrine is highly effective in producing immediate and sustained detumescence. “This report is, to the best of our knowledge, the first to demonstrate the safety and efficacy of this approach in an outpatient population of young patients with sickle-cell anaemia”, say Elpis Mantadakis and colleagues (University of Texas Southwestern Medical Center, Dallas, TX, USA). To date, a good, reliable treatment for priapism has not been established in patients with sicklecell anaemia because the results of many strategies are unpredictable, and side-effects can be serious. The approach used by Mantadakis and colleagues involved insertion of a needle into the corpus cavernosum, aspiration of as much blood as possible, and then irrigation of the corpora cavernosa with a 1:1 000 000 solution of epinephrine. During a 71-month period, 39
122
aspiration and irrigation procedures were done on 15 consecutive patients (mean age 13·7 years) with homozygous sickle-cell anaemia. The strategy produced detumescence within 1 minute on 37 occasions, and no hospital admissions were required. Seven patients had no recurrences at a mean follow-up of 39 months. Also, 12 evaluable patients reported normal erectile function at a follow-up of 40 months (Blood 2000; 95: 78–82). One of the authors, George Buchanan, highlights the importance of this “encouraging data regarding intermediate to longterm potency. Many reports fail to include information on this important outcome measure”, he notes. This is a “simple, safe, and readily available intervention [that] does not require hospitalization or regional or general anesthesia. Moreover, it is 95% effective”, write the researchers. It should be “the initial therapy employed for patients with sickle-cell anaemia and prolonged priapism”, they say.
Cloning takes another step Scientists report that they have produced six cloned cattle from fibroblasts taken from the ear of an adult bull and grown in culture for up to 3 months. This result indicates that it might be possible to produce cloned, genetically manipulated animals via easily obtained somatic cells. The results will be published in February in the Proceedings of the National Academy of Sciences.
Xavier Bosch
THE LANCET • Vol 355 • January 8, 2000
warns, pure hyaluronic acid preparations are extremely difficult, if not impossible, to obtain without some chondroitin sulphate A contamination. Beeson counters that “a variety
Science Photo Library
revious studies have shown that red blood cells infected with malarial parasites can accumulate in the placenta by interacting with chondroitin sulphate A on the placental lining. Now, researchers have identified hyaluronic acid as a second major receptor in the same tissue. Researchers have puzzled for decades over how the malaria parasite Plasmodium falciparum accumulates in the placenta, putting millions of pregnant women and their babies at risk every year. According to lead author James Beeson (Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia), these new results suggest that “by sticking to certain glycosaminoglycans in the placental lining, P falciparum manages to replicate in blood spaces in the placenta whilst ‘hidden’ from the full force of the host’s immune system”. Beeson and colleagues compared 15 placental isolates of P falciparuminfected erythrocytes with several non-placental isolates obtained from donors in Malawi for their ability to adhere to immobilised, purified hyaluronic acid. 12 of the 15 placental isolates showed substantial adhe-
P
Fatally attracted to placental membrane
of observations indicate that the adhesion could not be explained by such contamination”. Nevertheless, Hoffman would like to see follow-up studies and concludes that “if the results can be substantiated independently, they could lead to a more realistic and sophisticated approach to developing therapies to prevent malaria during pregnancy”. Kathryn Senior
Therapy for priapism in sickle-cell anaemia improved
News in brief
A
Hepatic metastases Outcome at 2 years is improved by hepatic arterial infusion of floxuridine and dexamethasone after resection of colorectal liver metastases, report Nancy Kemeny (Memorial SloanKettering Cancer Center, New York, USA) and co-workers. Their results—presented at last year’s American Society of Clinical Oncology (see Lancet 1999; 353: 1771)—show that patients treated with systemic fluorouracil have a relative risk of death of 2·34 compared with those treated with arterial infusion plus systemic therapy (N Engl J Med 1999; 341: 2039–48).
study of the management of prolonged priapism in young patients with sickle-cell anaemia has shown that aspiration of the corpora cavernosa followed by irrigation with epinephrine is highly effective in producing immediate and sustained detumescence. “This report is, to the best of our knowledge, the first to demonstrate the safety and efficacy of this approach in an outpatient population of young patients with sickle-cell anaemia”, say Elpis Mantadakis and colleagues (University of Texas Southwestern Medical Center, Dallas, TX, USA). To date, a good, reliable treatment for priapism has not been established in patients with sicklecell anaemia because the results of many strategies are unpredictable, and side-effects can be serious. The approach used by Mantadakis and colleagues involved insertion of a needle into the corpus cavernosum, aspiration of as much blood as possible, and then irrigation of the corpora cavernosa with a 1:1 000 000 solution of epinephrine. During a 71-month period, 39
122
aspiration and irrigation procedures were done on 15 consecutive patients (mean age 13·7 years) with homozygous sickle-cell anaemia. The strategy produced detumescence within 1 minute on 37 occasions, and no hospital admissions were required. Seven patients had no recurrences at a mean follow-up of 39 months. Also, 12 evaluable patients reported normal erectile function at a follow-up of 40 months (Blood 2000; 95: 78–82). One of the authors, George Buchanan, highlights the importance of this “encouraging data regarding intermediate to longterm potency. Many reports fail to include information on this important outcome measure”, he notes. This is a “simple, safe, and readily available intervention [that] does not require hospitalization or regional or general anesthesia. Moreover, it is 95% effective”, write the researchers. It should be “the initial therapy employed for patients with sickle-cell anaemia and prolonged priapism”, they say.
Cloning takes another step Scientists report that they have produced six cloned cattle from fibroblasts taken from the ear of an adult bull and grown in culture for up to 3 months. This result indicates that it might be possible to produce cloned, genetically manipulated animals via easily obtained somatic cells. The results will be published in February in the Proceedings of the National Academy of Sciences.
Xavier Bosch
THE LANCET • Vol 355 • January 8, 2000