- Email: [email protected]
Spinal cord monitoring
866
buildings and 70 Bq/m3 for new buildings, whereas the USA limit is
150 Bq/m3. Speakers
from Britain, Sweden, and the USA described their respective national radon action programmes. These countries have mounted campaigns to publicise the dangers of radon in highexposure areas and radon testing can be requested by householders (free in Britain and Sweden, a nominal cost in the USA). Advice is given on how to mitigate radon exposure in homes found to be above the action levels. Remedial actions are voluntary in the UK and USA, but in Sweden houses found to be above the action level can be declared insanitary and owners forced to take action. Unfortunately, because of public apathy on the subject of radon, only a fraction of at-risk homes in each country have been tested (from about a tenth in Britain to about a third in Sweden). The general public do not consider radon a serious environmental risk to health. In the USA, the public perception is that hazardous waste and nuclear power are the biggest environmental threats to health, with radon at the botton of the list, whereas the scientific consensus is that radon is the greatest threat and nuclear power the least. In Devon and Cornwall, a survey showed that people were much more worried about the possibility of a radiation leak from a proposed nuclear power station than about existing high levels of radiation from radon. Because radon is seen as a natural threat to which individual deaths cannot be-attributed, there is a general denial of the risk. Perhaps the greatest challenge faced by radon protection programmes is overcoming public inertia.
Neuronal
generation
Since undifferentiated cells from the brain of embryonic mice can be induced by epidermal growth factor (EGF) to proliferate and differentiate in culture into neurons, and since adult central nervous tissue contains EGF receptors, will brain cells from adult mice not behave likewise? Reynolds and Weiss decided to conduct their study with striatal cells from adult mice. These cells proliferated, acquired the morphological and antigenic features of neurons, and were immunoreactive for y-aminobutyric acid and substance P, two of the major neurotransmitters present in the striatum. One possible reason why the newly generated cells did not contain three other neurotransmitters found in the striatum-methionine-enkephalin, neuropeptide Y, or somatostatin-is that EGF-responsive progenitor cells are limited in the type of cell that they can produce. Another is that the other phenotypes may appear at different times or under different conditions. Reynolds and Weiss also found that poly-L-ornithine inhibited EGF-induced proliferation in vitro. Could the inability of stemcells to proliferate in vivo be due to the inhibitory influence of adult central nervous tissue and, if so, could poly-L-ornithine be one of these influences? Whatever the answers, Reynolds and Weiss’ work carries two, albeit long-term, implications. One is that if the substances that induce or inhibit neuronal proliferation and differentiation can be identified, there is the possibility that they can be used for the repair of central nervous system damage. The other is the possibility of using the newly generated cells for
transplantation. 1.
Reynolds BA, Weiss S. Generation of neurons and astrocytes from isolated cells of the adult mammalian central
nervous
system. Science 1992; 255: 1707-10.
Spinal cord monitoring To reduce the risk of paraplegia after spinal surgery surgeons (neurological and orthopaedic) often monitor spinal cord function by means of somatosensory-evoked potentials (SEPs).1 But postoperative paraplegia has been reported despite preserved SEPs. One explanation is that motor pathways might be more susceptible than sensory pathways to damage. If so, monitoring of both sensory and motor function seems desirable. However, spinal motor-evoked potentials (MEPs) are technically more difficult to elicit than SEPs, and they are affected by anaesthesia and muscle relaxants. Taylor2 reporting at the British Scoliosis Society meeting last week, records success with dual monitoring of SEPs and MEPs in all 40 patients studied. Two key factors contributed to the success with the MEP
technique. One was anaesthesia with propofol, which did not, unlike nitrous oxide and isoflurane, abolish MEPs (muscle relaxants, he found, could also be used). The other was to give, for stimuli applied in the upper thoracic region, two electrical pulses with an interstimulus interval of 1-2 ms to obtain, by temporal summation, a measurable response in the tibialis anterior. Enhancement of response in this way is necessary because of the synapses that the stimuli travelling down the cord have to cross. When applied at the lumbar region, only one pulse is necessary. The ease with which a response is obtained as stimuli are applied progressively down the cord increases sharply after about T8. This change suggests the presence of a polysynaptic pathway at this region, which might in turn account for the sensitivity of the cord to intraoperative injury at this level. The spinal MEP technique has been successfully adapted for use in monitoring cord function during surgery in two children with scoliosis due to hereditary sensory motor neuropathy (Charcot-Marie-Tooth disease)Poor conduction of afferent impulses along impaired peripheral nerves in this disorder makes SEPs difficult to obtain, but the intact central nervous system enables a good motor response to be evoked. 1. Editorial. Scoliosis: spinal cord monitoring during surgery. Lancet 1991; 338: 219-20. Taylor B. The method, rationale and results of spinal motor evoked potential (SMEP) spinal cord monitoring in scoliosis surgery.J Bone Joint Surg (Br) (in press). 3. Taylor BA, Fennelly M The spinal motor evoked potential allows intraoperative monitoring in sensorimotor neuropathy.J Bone Joint Surg (Br) (in press). 2.
Attack
on
health-care fraud
The US Department of Justice is marshalling resources to strengthen its attack on health-care fraud. It cites a General Accounting Office estimate that health-care fraud and abuse costs
Americans
more
than$50 billion
a
year. 50 Federal Bureau of
Investigation counterintelligence agents will be transferred to units specialising in health-care cases; they join the 46 other agents and 100 assistant US attorneys already working on such cases. Other agencies that are also allocating resources to combat health-care fraud include the Drug Enforcement Administration, the Postal Inspection Service, and the Department of Labor’s Inspector General. The initiative is being concentrated on twelve cities, and work will be coordinated by a new Health Care Fraud Unit, to which the Department of Justice has assigned six attorneys. So who will be the likely recipients of unwelcome attention from the fraud squad, whose strength has been increased not only in numbers but also by the availability of modem surveillance methods? They include those who sell unnecessary home medical equipment to elderly citizens and then bill Medicare; those who receive illegal kickbacks (in the past 3 years over$1 million has been recovered from 400 doctors in these schemes); those who take part in price-fixing schemes; and also those who resort to fraud in drug licensing applications.
Drugs and Therapeutics Bulletin Dr Andrew Herxheimer, who founded the Bulletin in 1962, has retired after 30 years as editor. The Bulletin, which started as the British edition of the American Medical Letter on Drugs and Therapeutics, is distributed free by government health departments to final year medical students and to doctors in most of the UK and in southern Ireland. It serves as source material for drug bulletins in many countries and is translated into Spanish for wide circulation in Central South America. Dr Joe Collier, formerly the deputy editor, has taken over as editor.
International
Diary
8th international symposium entitled Radionuclides in Nephrourology will be held in Chester, UK, on May 6-8: Mr P. H. O’Reilly, Department of Urology, Stepping Hill Hospital, Stockport, Cheshire SK2 7JE, UK
(061-419 5484). International workshop on Immunology of Human Papillomavirus Infections is to be held in Amsterdam, Netherlands, on May 7-8: Joke van Dam, Organising Secretary, Bureau PAOG, Tafelbergweg 25, 1105 BC Amsterdam, Netherlands (31 20-566 4801).
buildings and 70 Bq/m3 for new buildings, whereas the USA limit is
150 Bq/m3. Speakers
from Britain, Sweden, and the USA described their respective national radon action programmes. These countries have mounted campaigns to publicise the dangers of radon in highexposure areas and radon testing can be requested by householders (free in Britain and Sweden, a nominal cost in the USA). Advice is given on how to mitigate radon exposure in homes found to be above the action levels. Remedial actions are voluntary in the UK and USA, but in Sweden houses found to be above the action level can be declared insanitary and owners forced to take action. Unfortunately, because of public apathy on the subject of radon, only a fraction of at-risk homes in each country have been tested (from about a tenth in Britain to about a third in Sweden). The general public do not consider radon a serious environmental risk to health. In the USA, the public perception is that hazardous waste and nuclear power are the biggest environmental threats to health, with radon at the botton of the list, whereas the scientific consensus is that radon is the greatest threat and nuclear power the least. In Devon and Cornwall, a survey showed that people were much more worried about the possibility of a radiation leak from a proposed nuclear power station than about existing high levels of radiation from radon. Because radon is seen as a natural threat to which individual deaths cannot be-attributed, there is a general denial of the risk. Perhaps the greatest challenge faced by radon protection programmes is overcoming public inertia.
Neuronal
generation
Since undifferentiated cells from the brain of embryonic mice can be induced by epidermal growth factor (EGF) to proliferate and differentiate in culture into neurons, and since adult central nervous tissue contains EGF receptors, will brain cells from adult mice not behave likewise? Reynolds and Weiss decided to conduct their study with striatal cells from adult mice. These cells proliferated, acquired the morphological and antigenic features of neurons, and were immunoreactive for y-aminobutyric acid and substance P, two of the major neurotransmitters present in the striatum. One possible reason why the newly generated cells did not contain three other neurotransmitters found in the striatum-methionine-enkephalin, neuropeptide Y, or somatostatin-is that EGF-responsive progenitor cells are limited in the type of cell that they can produce. Another is that the other phenotypes may appear at different times or under different conditions. Reynolds and Weiss also found that poly-L-ornithine inhibited EGF-induced proliferation in vitro. Could the inability of stemcells to proliferate in vivo be due to the inhibitory influence of adult central nervous tissue and, if so, could poly-L-ornithine be one of these influences? Whatever the answers, Reynolds and Weiss’ work carries two, albeit long-term, implications. One is that if the substances that induce or inhibit neuronal proliferation and differentiation can be identified, there is the possibility that they can be used for the repair of central nervous system damage. The other is the possibility of using the newly generated cells for
transplantation. 1.
Reynolds BA, Weiss S. Generation of neurons and astrocytes from isolated cells of the adult mammalian central
nervous
system. Science 1992; 255: 1707-10.
Spinal cord monitoring To reduce the risk of paraplegia after spinal surgery surgeons (neurological and orthopaedic) often monitor spinal cord function by means of somatosensory-evoked potentials (SEPs).1 But postoperative paraplegia has been reported despite preserved SEPs. One explanation is that motor pathways might be more susceptible than sensory pathways to damage. If so, monitoring of both sensory and motor function seems desirable. However, spinal motor-evoked potentials (MEPs) are technically more difficult to elicit than SEPs, and they are affected by anaesthesia and muscle relaxants. Taylor2 reporting at the British Scoliosis Society meeting last week, records success with dual monitoring of SEPs and MEPs in all 40 patients studied. Two key factors contributed to the success with the MEP
technique. One was anaesthesia with propofol, which did not, unlike nitrous oxide and isoflurane, abolish MEPs (muscle relaxants, he found, could also be used). The other was to give, for stimuli applied in the upper thoracic region, two electrical pulses with an interstimulus interval of 1-2 ms to obtain, by temporal summation, a measurable response in the tibialis anterior. Enhancement of response in this way is necessary because of the synapses that the stimuli travelling down the cord have to cross. When applied at the lumbar region, only one pulse is necessary. The ease with which a response is obtained as stimuli are applied progressively down the cord increases sharply after about T8. This change suggests the presence of a polysynaptic pathway at this region, which might in turn account for the sensitivity of the cord to intraoperative injury at this level. The spinal MEP technique has been successfully adapted for use in monitoring cord function during surgery in two children with scoliosis due to hereditary sensory motor neuropathy (Charcot-Marie-Tooth disease)Poor conduction of afferent impulses along impaired peripheral nerves in this disorder makes SEPs difficult to obtain, but the intact central nervous system enables a good motor response to be evoked. 1. Editorial. Scoliosis: spinal cord monitoring during surgery. Lancet 1991; 338: 219-20. Taylor B. The method, rationale and results of spinal motor evoked potential (SMEP) spinal cord monitoring in scoliosis surgery.J Bone Joint Surg (Br) (in press). 3. Taylor BA, Fennelly M The spinal motor evoked potential allows intraoperative monitoring in sensorimotor neuropathy.J Bone Joint Surg (Br) (in press). 2.
Attack
on
health-care fraud
The US Department of Justice is marshalling resources to strengthen its attack on health-care fraud. It cites a General Accounting Office estimate that health-care fraud and abuse costs
Americans
more
than$50 billion
a
year. 50 Federal Bureau of
Investigation counterintelligence agents will be transferred to units specialising in health-care cases; they join the 46 other agents and 100 assistant US attorneys already working on such cases. Other agencies that are also allocating resources to combat health-care fraud include the Drug Enforcement Administration, the Postal Inspection Service, and the Department of Labor’s Inspector General. The initiative is being concentrated on twelve cities, and work will be coordinated by a new Health Care Fraud Unit, to which the Department of Justice has assigned six attorneys. So who will be the likely recipients of unwelcome attention from the fraud squad, whose strength has been increased not only in numbers but also by the availability of modem surveillance methods? They include those who sell unnecessary home medical equipment to elderly citizens and then bill Medicare; those who receive illegal kickbacks (in the past 3 years over$1 million has been recovered from 400 doctors in these schemes); those who take part in price-fixing schemes; and also those who resort to fraud in drug licensing applications.
Drugs and Therapeutics Bulletin Dr Andrew Herxheimer, who founded the Bulletin in 1962, has retired after 30 years as editor. The Bulletin, which started as the British edition of the American Medical Letter on Drugs and Therapeutics, is distributed free by government health departments to final year medical students and to doctors in most of the UK and in southern Ireland. It serves as source material for drug bulletins in many countries and is translated into Spanish for wide circulation in Central South America. Dr Joe Collier, formerly the deputy editor, has taken over as editor.
International
Diary
8th international symposium entitled Radionuclides in Nephrourology will be held in Chester, UK, on May 6-8: Mr P. H. O’Reilly, Department of Urology, Stepping Hill Hospital, Stockport, Cheshire SK2 7JE, UK
(061-419 5484). International workshop on Immunology of Human Papillomavirus Infections is to be held in Amsterdam, Netherlands, on May 7-8: Joke van Dam, Organising Secretary, Bureau PAOG, Tafelbergweg 25, 1105 BC Amsterdam, Netherlands (31 20-566 4801).