Italian doctors find pointer to mad cow drug
Doxorubicin: recent scientific abstracts
Derivative of amphotericin B: recent abstract
Sulfated glycans, petnosan and dextrin, stimulate endocytosis of the prion protein
Flupirtine, antagonist of the N-methyl-D-aspartate (NMDA), prevents neuuronal injury

Blood test an early guide to Alzheimer's
Blood test for ataxia
Organ transplant drugs promising in Alzheimer's

Italian doctors find pointer to mad cow drug

Reuter Information Service

LONDON (Oct 31, 1996) - Italian doctors say a commonly used drug prolongs the lives of hamsters infected with a variant of mad cow disease, and they hope it can point them in the direction of a cure for the brain-wasting condition. The drug, doxorubicin, is used to treat several forms of cancer but helps hamsters infected with scrapie to live longer, New Scientist magazine reported on Thursday.

Scrapie is the oldest of a family of diseases that include bovine spongiform encephalopathy (BSE or mad cow disease) and Creutzfeldt-Jakob Disease (CJD), which affects people.

The diseases are always fatal and there is no known cure. Worries that a BSE epidemic in Britain may cause a similar epidemic among people who eat beef make the search for a cure more urgent. Gianluigi Forloni and colleagues at the Mario Negri Institute for Pharmacological Research in Milan injected hamsters with iodoxorubicin, New Scientist reported. They then infected them with scrapie.

They also infected a second group of hamsters -- both with injections of scrapie-contaminated brain matter. Scrapie usually kills hamsters within three months. But the hamsters that got the drug lived two to three weeks longer. "The effects of the anticancer drug were extremely clear cut," Forloni told New Scientist. "They enabled the hamsters to live at least 20 percent longer."

Scrapie, BSE and CJD are all characterised by an altered brain protein called a prion. Forloni said the drug seemed to stop the prions from mutating. But doxorubicin is very toxic and the research does not show whether it would work if given after infection. It also has to be injected directly into the brain to work. "This might not have immediate applications, but it's a start," Moira Bruce of the Institute of Animal Health in Edinburgh told the magazine.

A second group of scientists, in France, have found an antifungal drug that may also work against BSE and CJD, the magazine said. Vincent Beringue and colleagues at the Atomic Energy Commission, which has been doing BSE research, found a derivative of amphotericin B helps lengthen the lives of mice withh scrapie.Unlike doxorubicin, it worked only after symptoms of the disease appeared.Both groups plan to publish their findings in major medical journals.


Derivative of amphotericin B helps in mouse scrapie

MS-8209, a new amphotericin B derivative, delays hamster scrapie.

Antimicrob. Agents Chemother. 39: 2810-2812 (1995)  [see also: Research in Virology 1996; 147(4) 213-8]

K. T. Adjou, R. Demaimay, C. Lasmezas, J. P. Deslys, M. Seman & D. Dormont
Department de la Recherche Medicale, Commissariat a l'Energie Atomique,France. 
To test the efficacy of a new amphotericin B derivative, MS-8209, in delaying scrapie, hamsters were infected intracerebrally with the 263K scrapie agent and treated with MS-8209 either early in the course of the disease or continuously. The results show that (i) all treatments lengthened the incubation period of hamster scrapie, (ii) continuous treatment with MS-8209 doubled the length of the incubation period compared with that observed in infected, untreated animals, and (iii) all treatments delayed the accumulation of a proteinase-resistant prion protein and glial fibrillary acidic protein in the brain. These findings suggest that MS-8209 is a powerful tool for investigating the pathogenesis of transmissible subacute spongiform encephalopathies.
Biochim Biophys Acta 1152: 189-91 (1993)

By using the whole-cell patch technique, it is shown that the total outward current is increased, as a function of time, after the addition of amphotericin B to the bathing solution. The whole-cell current is shown to be primarily a K-channel current by the blockage of this current upon application of TEA to the bathing solution. Single K-channel studies, using the outside-out patch-clamp technique, reveal that the single K-channel opening probability increases by a factor of six after the addition of amphotericin B.


Biochemistry 30: 77-82 (1991)

Amphotericin B (AmB) is a membrane-active antibiotic which has been shown to increase ion and small molecule permeability in a variety of model and biological membrane systems. A major mechanistic model, based on BLM systems, proposes that amphotericin forms barrellike pores with cholesterol which are cation selective when added to one side of the membrane and anion selective when added to both sides.


Antimicrob Agents Chemother 34: 1360-5 (1990)

Amphotericin B (AmB) is a potent antifungal polyene macrolide antibiotic and is the drug of choice for the treatment of deep-seated mycotic infections. Its use is limited, owing to its nephrotoxicity, and it must be dispersed in deoxycholate for parenteral administration. In contrast, AME (the monomethyl derivative of AmB) is water dispersible, is appreciably less cytotoxic than AmB toward a variety of cell types, and is reportedly active against the acquired immunodeficiency syndrome virus (human immunodeficiency virus type 1). The latter activity has generated interest in AME as an antiviral drug. However, AME is perceived to be neurotoxic, based on the outcome of a human clinical trial of AME as an antifungal drug. AmB is not regarded as neurotoxic, presumably because any neurotoxicity in vivo is precluded by its nephrotoxicity.


Doxorubicin Studies

Biochem Pharmacol 52: 713-22 (1996)

We have shown that hemin (iron-protoporphyrin IX) selectively counteracts doxorubicin (Adriamycin, ADR)-induced cytotoxicity on human leukemia K-562 cells by preventing ADR from inhibiting mitochondrial cytochrome c oxidase (COX), a novel target site for anthracyclines.


Anticancer Res 16: 1675-81 (1996)

By continuous exposure of CG5 human breast cancer cell line to increasing doxorubicin (Dx) concentrations, a multidrug-resistant (MDR) subline (CG5/Dx) was obtained. The resistant variant showed P-glycoprotein (P-gp) expression and a lower intracellular doxorubicin level than the parental cells.


Cancer Lett 105: 217-23 (1996)

Previous work by many groups has documented induction of the human immunodeficiency virus (HIV) long terminal repeat (LTR) following exposure of cells to ultraviolet light and other DNA damaging agents. Our experiments set out to determine the relative activation or repression of the HIV-LTR in response to two classes of chemotherapeutic agents: Doxorubicin is a DNA damage-inducing agent,


Mol Pharmacol 50: 243-8 (1996)

Tumor cell resistance to anthracyclines and epipodophyllotoxins can be due to reduced drug accumulation and/or alterations in the activity of topoisomerase II (TOPO II).


Cancer Chemother Pharmacol 38: 439-45 (1996)

The anthracyclines, in particular doxorubicin (DOX), have been used for the intra-arterial locoregional therapy of liver tumours for over two decades. However, the results obtained with this form of therapy have been disappointing. It is widely recognised that DOX has a slow and limited tissue uptake, and we hypothesised that lipophilic analogues could be more suitable for locoregional administration.


Blood 88: 309-18 (1996)

Clinical drug resistance may be attributed to the simultaneous selection and expression of genes modulating the uptake and metabolism of chemotherapeutic agents. P-glycoprotein (P-gp) functions as a membrane-associated drug efflux pump whose increased expression results in resistance to anthracyclines, epipodophyllotoxins, vinca alkaloids, and some alkylating agents. This type of resistance occurs as both de novo and acquired resistance to therapy for leukemia.


Blood 88: 633-44 (1996)

A major factor in limiting the efficacy of anthracyclines is overexpression of the MDR1-encoded p-glycoprotein (p-gp). A new analogue less affected by p-gp is annamycin (ANN), an anthracycline antibiotic with high affinity for lipid membranes and significantly more activity than doxorubicin (DOX)


Sulfated glycans stimulate endocytosis of the cellular isoform of the prion protein

J Biol Chem 270: 30221-30229 (1995) S. L. Shyng, S. Lehmann, K. L. Moulder & D. A. Harris Washington University School of Medicine, St. Louis, Missouri 63110, USA. There is currently no effective therapy for human prion diseases. However, several polyanionic glycans, including pentosan sulfate and dextran sulfate, prolong the incubation time of scrapie in rodents, and inhibit the production of the scrapie isoform of the prion protein (PrPSc), the major component of infectious prions, in cultured neuroblastoma cells. We report here that pentosan sulfate and related compounds rapidly and dramatically reduce the amount of PrPC, the non-infectious precursor of PrPSc, present on the cell surface. This effect results primarily from the ability of these agents to stimulate endocytosis of PrPC, thereby causing a redistribution of the protein from the plasma membrane to the cell interior. Pentosan sulfate also causes a change in the ultrastructural localization of PrPC, such that a portion of the protein molecules are shifted into late endosomes and/or lysosomes. In addition, we demonstrate, using PrP-containing bacterial fusion proteins, that cultured cells express saturable and specific surface binding sites for PrP, many of which are glycosaminoglycan molecules. Our results raise the possibility that sulfated glycans inhibit prion production by altering the cellular localization of PrPC precursor, and they indicate that endogenous proteoglycans are likely to play an important role in the cellular metabolism of both PrPC and PrPSc.
Here's another CJD drug, tested here in vitro. It is targeting a particular class of secondary symptoms arising from activated NMDA receptor. I don't think this strategy will prove fruitful; there are too many other things going on, such as heightened expression of tumor necrosis factor alpha (myelin pathologies), interleukin 1 alpha, and glial fibrillary acidic protein. etc. -- webmaster

Flupirtine partially prevents neuronal injury induced by prion protein

Perovic S; Pergande G; Ushijima H; Kelve M; Forrest J; Muller WE 
Neurodegeneration 4: 369-74 (1995) 
Flupirtine belongs to the class of triaminopyridines and is successfully applied clinically as a non-opiate analgesic drug with additional muscle relaxant properties. Recently it was reported that flupirtine acts like an antagonist of the N-methyl-D-aspartate (NMDA) receptor complex in neuronal cells both in vitro and in vivo. Here we have used primary cortical cells from rat embryos to demonstrate that this compound is also neuroprotective against the toxic effects caused by the prion agent PrPSc and lead acetate (Pb). These two agents display pleiotropic effects on neurons, which include activation of the NMDA receptor complex. At concentrations above 30 microM the toxic-peptide fragment of PrPSc causes apoptotic fragmentation of DNA and is consequently neurotoxic. Pb is neurotoxic at concentrations above 10 microM. Co-administration of flupirtine (10 microM) with either of these agents resulted in reduced neurotoxicity. These data indicate that the cytoprotective effect of flupirtine is measurable in vitro against these noxious agents which show their effects, including modulation of the NMDA receptor complex, pleiotropically.

Blood test an early guide to Alzheimer's

12.30.96 Associated Press

NEW YORK -- People with Alzheimer's appear to have unusually high levels of a certain protein in their blood, and a simple blood test might be able to diagnose the disease before its symptoms appear, a preliminary study suggests. That could give patients and families more time to plan for the future and might open the door to more effective treatment, said researcher Wilfred Jefferies.

In addition, tracking levels of the protein might quickly show how well medications are working, which could speed up development of new drugs and help doctors tailor therapy to patients, he said. But Jefferies emphasized that much more work is necessary to see if such a blood test would be useful.

Further studies in hundreds of people are needed to see if levels of the protein, called p97, are elevated before Alzheimer's becomes apparent, as well as whether high levels also appear in other neurological diseases or are unique to Alzheimer's, he said. In addition, it's not clear what the protein normally does in the body, why it would be elevated in Alzheimer's or what role it may play in the disease.

The work was reported in the November issue of the journal Nature Medicine by Jefferies, an associate professor in the Biotechnology Laboratory at the University of British Columbia in Vancouver, Canada; Malcolm Kennard and Dr. Howard Feldman of the university; and Dr. Tatsuo Yamada of Chiba University in Japan.

Zaven Khachaturian, director of the Alzheimer's Association Ronald and Nancy Reagan Research Institute, called the findings provocative and exciting. But he also emphasized that the work needs to be followed up before its usefulness can be known.

Jefferies and colleagues compared blood levels of p97 in 27 Canadians with probable Alzheimer's vs. 25 without it, as well as eight Japanese people with probable Alzheimer's vs. seven participants with other neurological diseases. Alzheimer's patients showed consistently higher p97 levels, well above those of the other participants. Levels of p97 appeared to be higher in more advanced cases, and a statistical analysis suggested that the protein levels might start to rise two years before symptoms of Alzheimer's appear.

Experts say brain deterioration in Alzheimer's begins some 20 to 40 years before symptoms appear and suggest that if treatments could be started during this early period, it might delay symptoms.


Organ transplant drugs promising in Alzheimer's and related diseases

Associated Press Oct 29, 1996

BALTIMORE -- Drugs developed for organ transplants are showing remarkable promise in a totally different area -- protecting nerve cells from damage and helping them regrow after injury, studies show. Derivatives of drugs such as FK506 and cyclosporin, which help keep the body from rejecting transplanted organs, may be useful in treating strokes and spinal cord damage, and Alzheimer's, Parkinson's and related diseases of the nervous system, neuroscientist Solomon Snyder said Monday.

In test-tube experiments, as well as trials in rats and monkeys, FK506 and cyclosporin, as well as modified versions of the drugs, can help restore damaged nerve cells. "It's clearly something worth studying," said Snyder, a professor of neuroscience, pharmacology and psychiatry at the Johns Hopkins University School of Medicine. Animal experiments have shown that the immunosuppressive drug FK506 and other drugs based on it can improve the regeneration of facial and other nerves that have been crushed. In test tubes the drugs also have stimulated regrowth in the kind of nerve cells that are important in Alzheimer's and Parkinson's disease.

But Bruce Gold, a professor at the Oregon Health Sciences University in Portland who has made important discoveries in the area, cautioned that it will be awhile before the drugs are used in humans.

"It's in the early experimental stages," he said. Now researchers are beginning to test the drug in monkeys that have a disorder similar to Parkinson's. If those tests go well, Snyder said, human tests of the drug could begin in a year or so. "It's preliminary, but let me tell you, it's working," he said.

Researchers found in the 1960s that they could shut down the body's immune system by interfering with a biochemical pathway that eventually causes an attack on materials alien to the body, such as a newly transplanted kidney or liver. Without the drugs that do that, organ transplants wouldn't be possible.

Neuroscientists recently discovered that key elements of that biochemical pathway also are present in the brain. And in a host of ailments, those same biochemical steps lead to processes that kill nerve cells.

So just as gumming up the immune system's works with FK506 and cyclosporin has proven beneficial, the hope is that similar strategies might work in the brain, spinal cord and other parts of the nervous system. "It's pretty remarkable in terms of what sorts of things one could dream up," Gold said.


Blood test for ataxia

Blood test for ataxia

Associated Press Oct 30, 1996

LOS ANGELES = -- Scientists have found the genetic defect responsible for one type of ataxia and developed a quick blood test for identifying people who have the brain-destroying disease or are almost certain to get it.= The development of the blood test represents a breakthrough for families with a history of inherited ataxia, because it could help them decide whether to have children and make other major decisions about their lives.

"It's fantastic news," said Donna Gruetzmacher, executive director of the 10,000-member National Ataxia Foundation. "Finally, people can know specifically what kind of ataxia they have in their family."= Ataxia is a slow, progressive disorder that robs people of of coordination and can eventually lead to dementia and death for thousands of Americans.

The newly discovered gene, called SCA2, is responsible for what is known as spinocerebellar ataxia type 2. The blood test can identify people who carry the defect and can also distinguish the disease from a host of other nervous system disorders with similar symptoms, such as multiple sclerosis.

In addition to making the blood test possible, the discovery of SCA2 also could help scientists in their search for a cure and a treatment. "There is no cure at this point, and there is no way at the moment to alter the course of the illness," said Dr. Stefan Pulst, the lead researcher and director of the Division of Neurology at Cedars-Sinai Medical Center. But he added: "I'm elated that we now have the gene and can start answering the next round of questions."

Pulst was to present his findings Wednesday at the annual meeting of the American Society for Human Genetics in San Francisco. Scientists previously identified the genetic defects responsible for two other major inherited forms of the disease, types 1 and 3, and developed blood tests for those, too.

Up until three years ago, doctors could diagnose cases of ataxia based on the patient's symptoms, but they had no way of distinguishing with certainty among the many types of the disease, some of which are not inherited. And they had no way of telling which people were at risk of the disease before they developed symptoms.

"It is likely this test will be relevant to thousands of patients with inherited ataxias," said Dr. Daniel Geschwind, an ataxia specialist at the University of California at Los Angeles. He said it also should help thousands more rule them out.

In types 1, 2 and 3, someone who carries one copy of the defective gene will almost certainly get the disease and has a 50 percent chance of passing it on to each child. The National Ataxia Foundation in Wayzata, Minn., estimates 150,000 Americans are affected or at risk for the family of diseases called hereditary ataxias. SCA2 is thought to account for thousands of these cases, but the exact number is unknown; the researchers led by Pulst tested only 50 families.

The disease kills cells in the brain's cerebellum, taking away balance and gradually destroying motor and mental function. Dr. Thomas Bird, a professor of neurology and medical genetics at the University of Washington in Seattle, called Pulst's work "a real step forward in terms of diagnosis." Knowing whether they have inherited the disorder lets people make choices about careers, financial planning and family planning, he said.

Pulst located the SCA2 gene on April 26. Researchers identified the gene for SCA1 in 1993 and for SCA3, also known as Machado-Joseph disease, in 1994. All three defects stem from too many copies of a three-unit genetic code for making glutamine, an amino acid found in many cell proteins.

Shirley Labruzzo, 56, of Syracuse, N.Y., lost her husband and a son to ataxia and now cares full-time for her son Daniel, 31, who suffers from severe tremors. She is anxious about her 34-year-old daughter, Nancy, who has no symptoms of ataxia but fears marrying and passing the gene on to a child. If Nancy is negative for SCA2, "it means my dreams and hers come true," Labruzzo said.


Blood test for ataxia

Associated Press Oct 30, 1996

LOS ANGELES = -- Scientists have found the genetic defect responsible for one type of ataxia and developed a quick blood test for identifying people who have the brain-destroying disease or are almost certain to get it.= The development of the blood test represents a breakthrough for families with a history of inherited ataxia, because it could help them decide whether to have children and make other major decisions about their lives.

"It's fantastic news," said Donna Gruetzmacher, executive director of the 10,000-member National Ataxia Foundation. "Finally, people can know specifically what kind of ataxia they have in their family."= Ataxia is a slow, progressive disorder that robs people of of coordination and can eventually lead to dementia and death for thousands of Americans.

The newly discovered gene, called SCA2, is responsible for what is known as spinocerebellar ataxia type 2. The blood test can identify people who carry the defect and can also distinguish the disease from a host of other nervous system disorders with similar symptoms, such as multiple sclerosis.

In addition to making the blood test possible, the discovery of SCA2 also could help scientists in their search for a cure and a treatment. "There is no cure at this point, and there is no way at the moment to alter the course of the illness," said Dr. Stefan Pulst, the lead researcher and director of the Division of Neurology at Cedars-Sinai Medical Center. But he added: "I'm elated that we now have the gene and can start answering the next round of questions."

Pulst was to present his findings Wednesday at the annual meeting of the American Society for Human Genetics in San Francisco. Scientists previously identified the genetic defects responsible for two other major inherited forms of the disease, types 1 and 3, and developed blood tests for those, too.

Up until three years ago, doctors could diagnose cases of ataxia based on the patient's symptoms, but they had no way of distinguishing with certainty among the many types of the disease, some of which are not inherited. And they had no way of telling which people were at risk of the disease before they developed symptoms.

"It is likely this test will be relevant to thousands of patients with inherited ataxias," said Dr. Daniel Geschwind, an ataxia specialist at the University of California at Los Angeles. He said it also should help thousands more rule them out.

In types 1, 2 and 3, someone who carries one copy of the defective gene will almost certainly get the disease and has a 50 percent chance of passing it on to each child. The National Ataxia Foundation in Wayzata, Minn., estimates 150,000 Americans are affected or at risk for the family of diseases called hereditary ataxias. SCA2 is thought to account for thousands of these cases, but the exact number is unknown; the researchers led by Pulst tested only 50 families.

The disease kills cells in the brain's cerebellum, taking away balance and gradually destroying motor and mental function. Dr. Thomas Bird, a professor of neurology and medical genetics at the University of Washington in Seattle, called Pulst's work "a real step forward in terms of diagnosis." Knowing whether they have inherited the disorder lets people make choices about careers, financial planning and family planning, he said.

Pulst located the SCA2 gene on April 26. Researchers identified the gene for SCA1 in 1993 and for SCA3, also known as Machado-Joseph disease, in 1994. All three defects stem from too many copies of a three-unit genetic code for making glutamine, an amino acid found in many cell proteins.

Shirley Labruzzo, 56, of Syracuse, N.Y., lost her husband and a son to ataxia and now cares full-time for her son Daniel, 31, who suffers from severe tremors. She is anxious about her 34-year-old daughter, Nancy, who has no symptoms of ataxia but fears marrying and passing the gene on to a child. If Nancy is negative for SCA2, "it means my dreams and hers come true," Labruzzo said.