Evidence for a role for α6(∗) nAChRs in l-dopa-induced dyskinesias using Parkinsonian α6(∗) nAChR gain-of-function mice

l-Dopa-induced dyskinesias (LIDs) are a serious side effect of dopamine replacement therapy for Parkinson's disease. The mechanisms that underlie LIDs are currently unclear. However, preclinical studies indicate that nicotinic acetylcholine receptors (nAChRs) play a role, suggesting that drugs targeting these receptors may be of therapeutic benefit. To further understand the involvement of α6β2(∗) nAChRs in LIDs, we used gain-of-function α6(∗) nAChR (α6L9S) mice that exhibit a 20-fold enhanced sensitivity to nAChR agonists. Wildtype (WT) and α6L9S mice were lesioned by unilateral injection of 6-hydroxydopamine (6-OHDA, 3μg/ml) into the medial forebrain bundle. Three to 4wk later, they were administered l-dopa (3mg/kg) plus benserazide (15mg/kg) until stably dyskinetic. l-dopa-induced abnormal involuntary movements (AIMs) were similar in α6L9S and WT mice. WT mice were then given nicotine in the drinking water in gradually increasing doses to a final 300μg/ml, which resulted in a 40% decline AIMs. By contrast, there was no decrease in AIMs in α6L9S mice at a maximally tolerated nicotine dose of 20μg/ml. However, the nAChR antagonist mecamylamine (1mg/kg ip 30min before l-dopa) reduced l-dopa-induced AIMs in both α6L9S and WT mice. Thus, both a nAChR agonist and antagonist decreased AIMs in WT mice, but only the antagonist was effective in α6L9S mice. Since nicotine appears to reduce LIDs via desensitization, hypersensitive α6β2(∗) nAChRs may desensitize less readily. The present data show that α6β2(∗) nAChRs are key regulators of LIDs, and may be useful therapeutic targets for their management in Parkinson's disease.

On the coupling number and characteristic length of micropolar media of differing topology

In planar micropolar elasticity theory, the degree of micropolarity exhibited by a loaded heterogeneous material is quantified by a dimensionless constitutive parameter, the coupling number. Theoretical predictions of this parameter derived by considering the mechanical behaviour of regular, two-dimensional lattices with straight connectors suggest that its value is dependent on the connectivity or topology of the lattice with the coupling number in a square lattice predicted to be notably higher than in its hexagonal counterpart. A second constitutive parameter reflecting the intrinsic lattice size scale, the characteristic length, is also predicted to be topology-dependent. In this paper, we compare the behaviour of alternative two-dimensional heterogeneous materials in the context of micropolar elasticity. These materials consist of periodic arrays of circular voids within a polymeric matrix rather than a lattice of straight connectors. Two material variants that differ only in their matrix topology are investigated in particular. Values of the additional micropolar constitutive parameters are obtained for each material from both experimental tests and finite-element analyses. The values determined for these parameters, particularly the coupling number, suggest that their topological dependence differs appreciably from the theoretical predictions of the lattice models.

The clinical effectiveness of negative pressure wound therapy: a systematic review

OBJECTIVE

To estimate the efficacy of negative pressure wound therapy (NPWT), on the basis of a systematic review of reported randomised controlled trials (RCTs).

METHOD

A systematic literature search for relevant RCTs was carried out. The credibility of the outcome of each study was evaluated using a specially constructed instrument.

RESULTS

We identified 17 RCTs, of which five had not been included in previous reviews or health technology assessments. For diabetic foot ulcers (seven RCTs), there was consistent evidence of the benefit of NPWT compared with control treatments. For pressure ulcers (three RCTs), results were conflicting. In trials involving mixed wounds (five RCTs), evidence was encouraging but of inadequate quality. Significant complications were not increased.

CONCLUSION

There is now sufficient evidence to show that NPWT is safe, and will accelerate healing, to justify its use in the treatment of diabetes-associated chronic leg wounds. There is also evidence, though of poor quality, to suggest that healing of other wounds may also be accelerated.

An evaluation of some of the methods currently available for the production of leucocyte-poor blood

Four methods used for the production of leucocyte-poor blood were compared: liquid nitrogen recovery and washing, washing alone, the Imugard filter and the Leuko-Pak filter. Twenty units of blood were tested by each technique. Liquid nitrogen recovery and washing, and the Imugard filter removed over 95% of white cells, and 95% and 56% respectively of platelets. Washing alone was unreliable and removed on average 47% of white cells and 85% of platelets. The Leuko-Pak filter removed on average 42% of white cells and 79% of platelets.

Longitudinal prescribing patterns for psychoactive medications in community-based individuals with developmental disabilities: utilization of pharmacy records

BACKGROUND

Little is known about longitudinal prescribing practices for psychoactive medications for individuals with intellectual disabilities and developmental disabilities (IDDD) who are living in community settings.

METHODS

Computerized pharmacy records were accessed for 2344 community-based individuals with IDDD for whom a total of 3421 prescriptions were written during a 17-month period of study. Forty-two psychoactive medications were rank ordered in terms of prescription frequency.

RESULTS

Fifty-two per cent (52%) of all prescriptions written during the study period were for psychoactive medications. Anticonvulsant, antipsychotic and antidepressant medications were the most commonly filled prescriptions among psychoactive medications. Sixty per cent (62%) of the study population was given prescriptions for more than one psychoactive medication and 36% received three or more psychoactive medications. During the study period there was a statistically significant increase in prescriptions filled for olanzapine, risperidone, valproic acid, and clonazepam whereas prescriptions filled for thioridazine, haloperidol, and benzotropine showed a significant decline (P < 0.05-0.001). Distribution of psychoactive drug class by age showed that the majority of prescriptions were filled for individuals between 20 and 50 years with the exception of prescriptions for psychostimulants which peaked for individuals prior to 20 years.

CONCLUSIONS

(1) Analysis of pharmacy billing records provides a method for assessing prescribing patterns of psychoactive medications in community-based individuals with IDDD. (2) Polypharmacy for psychoactive medications is prevalent in this setting. (3) The second-generation antipsychotic medications are prominently represented by an increasing number of filled prescriptions during the study period.

Adaptation of influenza A viruses to cells expressing low levels of sialic acid leads to loss of neuraminidase activity

Influenza A viruses possess two virion surface proteins, hemagglutinin (HA) and neuraminidase (NA). The HA binds to sialyloligosaccharide viral receptors, while the NA removes sialic acids from the host cell and viral sialyloligosaccarides. Alterations of the HA occur during adaptation of influenza viruses to new host species, as in the 1957 and 1968 influenza pandemics. To gain a better understanding of the contributions of the HA and possibly the NA to this process, we generated cell lines expressing reduced levels of the influenza virus receptor determinant, sialic acid, by selecting Madin-Darby canine kidney cells resistant to a lectin specific for sialic acid linked to galactose by alpha(2-3) or alpha(2-6) linkages. One of these cell lines had less than 1/10 as much N-acetylneuraminic acid as its parent cell line. When serially passaged in this cell line, human H3N2 viruses lost sialidase activity due to a large internal deletion in the NA gene, without alteration of the HA gene. These findings indicate that NA mutations can contribute to the adaptation of influenza A virus to new host environments and hence may play a role in the transmission of virus across species.

Chronic care clinics for diabetes in primary care: a system-wide randomized trial

OBJECTIVE

To evaluate the impact of primary care group visits (chronic care clinics) on the process and outcome of care for diabetic patients.

RESEARCH DESIGN AND METHODS

We evaluated the intervention in primary care practices randomized to intervention and control groups in a large-staff model health maintenance organization (HMO). Patients included diabetic patients > or = 30 years of age in each participating primary care practice, selected at random from an automated diabetes registry. Primary care practices were randomized within clinics to either a chronic care clinic (intervention) group or a usual care (control) group. The intervention group conducted periodic one-half day chronic care clinics for groups of approximately 8 diabetic patients in their respective doctor's practice. Chronic care clinics consisted of standardized assessments; visits with the primary care physician, nurse, and clinical pharmacist; and a group education/peer support meeting. We collected self-report questionnaires from patients and data from administrative systems. The questionnaires were mailed, and telephoned interviews were conducted for nonrespondents, at baseline and at 12 and 24 months; we queried the process of care received, the satisfaction with care, and the health status of each patient. Serum cholesterol and HbA1c levels and health care use and cost data was collected from HMO administrative systems.

RESULTS

In an intention-to-treat analysis at 24 months, the intervention group had received significantly more recommended preventive procedures and helpful patient education. Of five primary health status indicators examined, two (SF-36 general health and bed disability days) were significantly better in the intervention group. Compared with control patients, intervention patients had slightly more primary care visits, but significantly fewer specialty and emergency room visits. Among intervention participants, we found consistently positive associations between the number of chronic care clinics attended and a number of outcomes, including patient satisfaction and HbA1c levels.

CONCLUSIONS

Periodic primary care sessions organized to meet the complex needs of diabetic patients imrproved the process of diabetes care and were associated with better outcomes.

No evidence of infection with porcine endogenous retrovirus in recipients of encapsulated porcine islet xenografts

Transplantation of pig tissues into humans has the potential for cotransferring pig infections. Knowledge of the epidemiology of pig infections transmissible to humans allows the development of risk limitation strategies at the source herd level, but potentially infectious pig endogenous retrovirus (PERV) is ubiquitous in all domestic pigs and therefore is not avoidable. Using a specific and sensitive RT-PCR and nested PCR for PERV nucleic acids with primers, the screening of pigs from New Zealand herds for the presence and expression of the PERV was conducted. The presence of PERV proviral DNA (pol and env region) and viral RNA was demonstrated in all tested pig tissues including pancreas, liver, spleen, brain, heart, and PBMC. Using the same assays it was established that different tissues (liver, spleen, and heart) of nude and nonobese diabetic (NOD) mice previously transplanted with nonencapsulated pig islets were PERV DNA and RNA negative. Alginate polylysine capsules prepared with encapsulated pig islets were tested for possible leakage of viral particles or viral nucleic acids. RNA was extracted from the supernatant of viable encapsulated pig islet cells grown in culture for 2 months. No evidence of PERV RNA or of cellular nucleic acids could be found. Two adult type I diabetic subjects were transplanted with 1 x 10(6) neonatal pig islets encased in alginate capsules into the peritoneal cavity. One patient was immunosuppressed. Both showed evidence of graft function (up to 34% reduction in insulin dose, corresponding increase in serum pig C-peptide) for up to 2 years. DNA and RNA were extracted from PBMC and blood plasma of both patients at 19 months posttransplant. No evidence of PERV proviral DNA or RNA could be detected. Piglet islets contain PERV DNA and RNA, but this does not traverse the capsules used or produce any evidence of infection in nude and nonobese diabetic (NOD) mice or humans.

Influenza A viruses lacking sialidase activity can undergo multiple cycles of replication in cell culture, eggs, or mice

Influenza A viruses possess both hemagglutinin (HA), which is responsible for binding to the terminal sialic acid of sialyloligosaccharides on the cell surface, and neuraminidase (NA), which contains sialidase activity that removes sialic acid from sialyloligosaccharides. Interplay between HA receptor-binding and NA receptor-destroying sialidase activity appears to be important for replication of the virus. Previous studies by others have shown that influenza A viruses lacking sialidase activity can undergo multiple cycles of replication if sialidase activity is provided exogenously. To investigate the sialidase requirement of influenza viruses further, we generated a series of sialidase-deficient mutants. Although their growth was less efficient than that of the parental NA-dependent virus, these viruses underwent multiple cycles of replication in cell culture, eggs, and mice. To understand the molecular basis of this viral growth adaptation in the absence of sialidase activity, we investigated changes in the HA receptor-binding affinity of the sialidase-deficient mutants. The results show that mutations around the HA receptor-binding pocket reduce the virus's affinity for cellular receptors, compensating for the loss of sialidase. Thus, sialidase activity is not absolutely required in the influenza A virus life cycle but appears to be necessary for efficient virus replication.

Implantable ventricular assist devices: is it time to introduce them in Canada?

BACKGROUND

Implantable left ventricular assist devices (LVAD) are increasingly used in Europe and the United States. Any decision to use them in Canada requires estimates of their clinical value and costs.

MATERIALS AND METHODS

No randomized controlled trials are available. Clinical value and costs, concerning principally the HeartMate and Novacor devices, were estimated based on reports of uncontrolled case series obtained through MEDLINE (1993 to 1999), review articles, three technology assessments and data supplied by the manufacturers.

RESULTS AND DISCUSSION

Reasonably trouble-free device function can be expected for three to four years. The principal application is as a bridge to transplantation. Rarely, the heart recovers without transplantation. Use as 'permanent' support of the failing heart is still contentious. Approximately 70% of patients with an implanted LVAD survive until recovery or transplantation. Complications are hemorrhage, principally postoperative, 20% to 44%; thromboembolism, ranging from 5% to 15% for the HeartMate to 12% to 37% for Novacor; and significant infection, 50%. Quality of life is slightly inferior to that of patients with transplanted hearts. The direct cost to the health care system of installation is approximately $138,000. As a bridge to transplantation, the estimated cost effectiveness of elective interventions is $91,000 to $126,000 per life-year saved ($117,000 to $186,000, discounted at 5%), and as a permanent alternative to transplantation, the cost per life-year is $52,000 to $60,000 ($50, 000 to $58,000, discounted at 5%), according to circumstances. As a bridge to 50 transplantations per year, the approximate annual cost would be $7 to $13 million (exclusive of transplantation costs). As 'permanent' support for 7000 patients per year, the approximate cost would be $2,661 million per year.

CONCLUSIONS

Limited application in a limited number of centres with collection of all data is justifiable at this stage.

Offering HIV prophylaxis to people who have been sexually assaulted: 16 months' experience in a sexual assault service

The sexual assault service, operated by the Children's & Women's Health Centre of British Columbia in partnership with the Vancouver General Hospital Emergency Department, started offering HIV prophylaxis in November 1996 to patients presenting to the emergency department after a sexual assault. In the first 16 months of the program a total of 258 people were seen by the service, of whom 71 accepted the offer of HIV prophylaxis. Only 29 continued with the drug treatment after receiving the initial 5-day starter pack, and only 8 completed the full 4-week treatment regmen and returned for their final follow-up visit. Patients at highest risk for HIV infection (those who had penetration by an assailant known to be HIV positive or at high risk for HIV infection [men who have sex with men, injection drug users]) were more likely to accept prophylaxis and more likely to complete the treatment than those at lower risk. Compliance and follow-up were the main problems with implementing this service. Service providers found it difficult to give the information about HIV prophylaxis to traumatized patients. After this program evaluation, the service changed its policy to offer HIV prophylaxis only to people at high risk of HIV infection. This targeting of services is expected to make the service providers' jobs easier and to make the program more cost-effective while still protecting sexual assault victims against HIV infection.

Risk factors and precipitating neck movements causing vertebrobasilar artery dissection after cervical trauma and spinal manipulation

STUDY DESIGN

Potential precipitating events and risk factors for vertebrobasilar artery dissection were reviewed in an analysis of the English language literature published before 1993.

OBJECTIVES

To assess the literature pertaining to precipitating neck movements and risk factors for vertebrobasilar artery dissection in an attempt to determine whether the incidence of these complications can be minimized.

SUMMARY OF BACKGROUND DATA

Vertebrobasilar artery dissection and occlusion leading to brain stem and cerebellar ischemia and infarction are rare but often devastating complications of cervical, manipulation and neck trauma. Although various investigators have suggested potential risk factors and precipitating events, the basis for these suggestions remains unclear.

METHODS

A detailed search of the literature using three computerized bibliographic databases was performed to identify English language articles from 1966 to 1993. Literature before 1966 was identified through a hand search of Index Medicus. References of articles obtained by database search were reviewed to identify additional relevant articles. Data presented in all articles meeting the inclusion criteria were summarized.

RESULTS

The 367 case reports included in this study describe 160 cases of spontaneous onset, 115 cases of onset after spinal manipulation, 58 cases associated with trivial trauma, and 37 cases caused by major trauma (3 cases were classified in two categories). The nature of the precipitating trauma, neck movement, or type of manipulation that was performed was poorly defined in the literature, and it was not possible to identify a specific neck movement or trauma that would be considered the offending activity in the majority of cases. There were 208 (57%) men and 158 (43%) women (gender data not reported in one case) with an average age of 39.3 +/- 12.9 years. There was an overall prevalence of 13.4% hypertension, 6.5% migraines, 18% use of oral contraception (percent of female patients), and 4.9% smoking. In only isolated cases was specific vascular disease such as fibromuscular hyperplasia noted.

CONCLUSIONS

The literature does not assist in the identification of the offending mechanical trauma, neck movement, or type of manipulation precipitating vertebrobasilar artery dissection or the identification of the patient at risk. Thus, given the current status of the literature, it is impossible to advise patients or physicians about how to avoid vertebrobasilar artery dissection when considering cervical manipulation or about specific sports or exercises that result in neck movement or trauma.

Biological heterogeneity, including systemic replication in mice, of H5N1 influenza A virus isolates from humans in Hong Kong

An H5N1 avian influenza A virus was transmitted to humans in Hong Kong in 1997. Although the virus causes systemic infection and is highly lethal in chickens because of the susceptibility of the hemagglutinin to furin and PC6 proteases, it is not known whether it also causes systemic infection in humans. The clinical outcomes of infection in Hong Kong residents ranged widely, from mild respiratory disease to multiple organ failure leading to death. Therefore, to understand the pathogenesis of influenza due to these H5N1 isolates, we investigated their virulence in mice. The results identified two distinct groups of viruses: group 1, for which the dose lethal for 50% of mice (MLD50) was between 0.3 and 11 PFU, and group 2, for which the MLD50 was more than 10(3) PFU. One day after intranasal inoculation of mice with 100 PFU of group 1 viruses, the virus titer in lungs was 10(7) PFU/g or 3 log units higher than that for group 2 viruses. Both types of viruses had replicated to high titers (>10(6) PFU/g) in the lungs by day 3 and maintained these titers through day 6. More importantly, only the group 1 viruses caused systemic infection, replicating in nonrespiratory organs, including the brain. Immunohistochemical analysis demonstrated the replication of a group 1 virus in brain neurons and glial cells and in cardiac myofibers. Phylogenetic analysis of all viral genes showed that both groups of Hong Kong H5N1 viruses had formed a lineage distinct from those of other viruses and that genetic reassortment between H5N1 and H1 or H3 human viruses had not occurred. Since mice and humans harbor both the furin and the PC6 proteases, we suggest that the virulence mechanism responsible for the lethality of influenza viruses in birds also operates in mammalian hosts. The failure of some H5N1 viruses to produce systemic infection in our model indicates that multiple, still-to-be-identified, factors contribute to the severity of H5N1 infection in mammals. In addition, the ability of these viruses to produce systemic infection in mice and the clear differences in pathogenicity among the isolates studied here indicate that this system provides a useful model for studying the pathogenesis of avian influenza virus infection in mammals.

Use of abciximab (c7E3 Fab, ReoPro) as an adjunct to balloon angioplasty

OBJECTIVE

To estimate the magnitude of the clinical benefits that may result from use of abciximab at the time of angioplasty and the cost of achieving them.

DATA SOURCES

Four published randomized control trials.

DATA SYNTHESIS

Meta-analysis of outcomes at six months.

RESULTS

Use of abciximab in comparable high risk populations, in the manner described in these trials, is estimated to have the following effects: It does nto influence mortality within the first six months. It reduces the rate of myocardial infarction (MI) by 3.3/100 treatments with a 95% CI of 1.6 to 5.2. It may reduce the need for revascularization (angioplasty or coronary artery bypass graft) by 2.1/100 treatments (95% CI -1.0 to 5.0). It does not cause any significant increase in major hemorrhagic events. There is no evidence that it influences restenosis rates. The net cost per MI prevented would be approximately $44,000, ranging from approximately $29,000 to $71,000 on sensitivity analysis. The net cost per adverse event prevented (MI plus revascularization procedure) would be approximately $27,000 (sensitivity analysis $16,000 to $57,000). Use of abciximab for all of the approximately 17,487 angioplasties carried out in Canada each year may prevent 395 myocardial infarcts and 186 revascularization procedures, at an overall cost of approximately $29 million and a cost effectiveness of approximately $50,000 per adverse event prevented. (This assumes the same proportional reduction in events as in these four studies, and that 35% of procedures are high risk).

SIGNIFICANCE

Possible eventual prolongation of life due to fewer periprocedural MIs with abciximab use cannot be quantified. Thus, these estimates of cost effectiveness cannot be used to compare this intervention directly with others in terms of dollars per life year saved. The field is evolving rapidly and these conclusions may soon have to be modified. Increasing use of stents will probably slightly reduce, but not abolish, the health benefits of abciximab use. These estimates are based on only four trials. However, until more trials are completed they provide the best available evidence on which to base policy decisions.

Screening for prostate cancer: estimating the magnitude of overdetection

BACKGROUND

No randomized controlled trial of prostate cancer screening has been reported and none is likely to be completed in the near future. In the absence of direct evidence, the decision to screen must therefore be based on estimates of benefits and risks. The main risk of screening is overdetection--the detection of cancer that, if left untreated, would not cause death. In this study the authors estimate the level of overdetection that might result from annual screening of men aged 50-70.

METHODS

The annual rate of lethal screen-detectable cancer (detectable cancer that would prove fatal before age 85 if left untreated) was calculated from the observed prostate cancer mortality rate in Quebec; the annual rate of all cases of screen-detectable prostate cancer was calculated from 2 recent screening studies.

RESULTS

The annual rate of lethal screen-detectable prostate cancer was estimated to be 1.3 per 1000 men. The annual rate of all cases of screen-detectable prostate cancer was estimated to be 8.0 per 1000 men. The estimated case-fatality rate among men up to 85 years of age was 16% (1.3/8.0) (sensitivity analysis 13% to 22%).

INTERPRETATION

Of every 100 men with screen-detected prostate cancer, only 16 on average (13 to 22) could have their lives extended by surgery, since the prostate cancer would not cause death before age 85 in the remaining 84 (78 to 87).

Mink lung epithelial cells: unique cell line that supports influenza A and B virus replication

We have demonstrated for the first time that a mink lung epithelial cell line (Mv1Lu) supports the replication of influenza A and B viruses, including the recently isolated H5N1 avian and human Hong Kong strains, to titers comparable to those in MDCK cells. These results suggest that Mv1Lu cells might serve as an alternative system for the isolation and cultivation of influenza A and B viruses and may be useful for vaccine development.

In vivo gene transfer to skin and wound by microseeding

BACKGROUND

Gene transfer to skin has many potential applications but lacks a safe, practical delivery method. This report presents a new technique, microseeding, for in vivo gene transfer to skin and wounds and for DNA-mediated vaccination. The plasmid DNA solution was delivered directly to the target cells of the skin by a set of oscillating solid microneedles driven by a modified tattooing device.

MATERIALS AND METHODS

Skin and partial-thickness excisional wounds in pigs were microseeded with either hEGF expression plasmid or beta-galactosidase expression plasmid. Human EGF was also delivered by single injection or particle bombardment. hEGF expression in wound fluid and in target tissue was determined by ELISA with anti-hEGF-specific antibodies. Additionally, weanling pigs were microseeded with a hemagglutinin of swine influenza virus expression plasmid and production of anti-HA-specific antibodies was determined by blocking ELISA.

RESULTS

hEGF expression in microseeded partial thickness wounds (5664 pg/site) and skin sites (969 pg/site) peaked 2 days after transfection being four- to seven-fold higher than gene transfer by a single intradermal injection and two- to three-fold higher than particle-mediated gene transfer. The beta-galactosidase-expressing cells were detected in dermis and epidermis. Pigs microseeded with HA expression plasmid were protected from infection by the Swine influenza virus.

CONCLUSIONS

These results demonstrate that microseeding is a simple and effective method for in vivo gene transfer to skin and wounds and is more efficient than single injection and particle-mediated gene transfer.

Coverage of drug costs: reference-based pricing

Since 1985, British Columbia has used reference-based pricing (RBP) as a basis for reimbursement of the cost of an increasing number of drugs. Under this policy the costs of certain drugs are reimbursed at a level determined by the price of the lowest priced drug of equal efficacy in the same category. A recent position paper of the Canadian Cardiovascular Society has roundly criticized this policy. The principal grounds for criticism are that the policy is not 'evidenced based', that it is ineffective in that it does not lower health care costs, and that it contravenes the principals of equity and accessibility. These claims were examined and determined to be ill founded. Because the British Columbia experiment seems to be a reasonable approach to restraining drug costs it should be continued and monitored closely. In this way, real evidence of the impact of RBP on health and health care costs in the context of the Canadian health care system can be obtained.

Use of chiropractic manipulation in lumbar rehabilitation

The beneficial effects of manipulation in relieving symptoms and enhancing spinal flexibility can be a valuable tool in the transition of persons with low back pain into lumbar rehabilitation programs. Manipulation may hasten their entry into active care, or permit them to complete programs that might otherwise be interrupted by symptomatic recurrence. Manipulation science and technical procedures are reviewed as a basis to help understand the utility of properly integrated chiropractic manipulation strategies.

Manipulation of immune responses via particle-mediated polynucleotide vaccines

Polynucleotide vaccines are a new approach to immunization that promises qualitative advances in vaccine technology. These vaccines mimic infection in that they result in expression of pathogen gene products in situ, which can elicit both cell-mediated immune responses and humoral responses. This approach has been applied primarily to vaccines against viral diseases, but may be significant for vaccines directed toward bacterial pathogens. Auragen has developed a generally applicable gene transfer technology and, for vaccine applications, has focused on particle-mediated gene transfer to epidermis. Results demonstrate that Accell polynucleotide vaccines induce immune responses toward human immunodefficiency virus (HIV) antigens, influenza A virus antigens, and hepatitis B virus (HBV) antigens in rodent,s swine and primates. Cellular immune responses toward these antigens have been demonstrated in rodents. In a swine influenza a challenge model Accell vaccination provides protection equivalent to that of a commercial killed-whole-virus vaccine. Vaccination of mice by this method toward a Chlamydia pneumoniae major outer-membrane protein elicits a species-specific antibody response.

Assessing the impact of health technology assessment

Methodology for evaluation of impact of health technology assessments (HTAs) is outlined and its use illustrated by applying it to 21 HTAs produced by CETS. Impact on policies and technology diffusion was identified in documents, through interviews, questionnaires, and use of data banks. There was evidence that all but three reports influenced policy and that cost-minimization studies caused savings of between $16 million and $27 million annually. Precise estimates of impact will seldom be possible, but systematic documentation of effects is feasible.

Cost effectiveness of screening for primary open angle glaucoma

OBJECTIVES AND SETTING

To determine the cost effectiveness of screening for glaucoma.

METHODS

Information on treatment efficacy, diagnostic methods, epidemiological characteristics of glaucoma, and costs were determined from the literature, from administrative databases, and from experts. Scenarios with different screening frequency, age, participation in screening, compliance with treatment, treatment efficacy, and diagnostic tests were examined.

RESULTS

The initial scenario comprised three-yearly screening of subjects aged 40-79 by funduscopy and tonometry, followed by perimetry when abnormalities were discovered. The assumption of levels of participation in screening and of compliance with treatment of 75%, and treatment efficacy of 50% resulted in a cost of $C100,000 per year of blindness prevented. A scenario in which screening was restricted to subjects aged 65-79, with the same input variables, would prevent 81% of the cases of blindness prevented with scenario 1, at a cost of $C42,000 per year of blindness prevented. Screening with tonometry only as the initial diagnostic test in subjects aged 65-79 would result in a cost of $C36,000 per year of blindness prevented, but would only prevent 59% of the cases prevented with scenario 1.

CONCLUSIONS

There is as yet no proof that treatment of glaucoma or of high intraocular pressure will arrest the progression of glaucoma to blindness. Even when treatment efficacy is assumed to be as high as 50%, however, the cost effectiveness of most glaucoma screening programmes considered would not be competitive.

How has extracorporeal shock-wave lithotripsy changed the treatment of urinary stones in Quebec?

OBJECTIVES

To determine the number of people who underwent treatment of urinary stones in Quebec before and after the introduction of extracorporeal shock-wave lithotripsy (ESWL) and to determine how the introduction of ESWL influenced resource utilization.

DESIGN

Before-after study; data were obtained from administrative databases and hospital-based cost estimates.

SETTING

The 68 acute care hospitals in Quebec in which treatment of urinary stones is undertaken.

PATIENTS

Quebec residents admitted to hospital for treatment of urinary stones between the fiscal years 1984 and 1992.

OUTCOME MEASURES

Number of people treated for urinary stones per year, total number of procedures per year (including open surgery, percutaneous procedures, retrograde procedures and ESWL), and annual resources (including number of hospital bed-days and direct costs) for treatment of urinary stones used overall and in hospitals with and without ESWL services.

RESULTS

Over the study period the number of people treated for urinary stones increased by 59%. As well, the combined frequency of ESWL and surgery (the two main treatment methods) increased by 107%. These increases were largely due to rates of treatment that grew by 52% among women and by 34% among men. The total number of hospital bed-days decreased by 28%, which reflected shorter hospital stays for ESWL. However, despite this decrease, the total direct annual costs were 7% higher in 1992 than in 1984 because of the increased numbers of people treated and procedures performed. In the three hospitals that offered ESWL the number of hospital bed-days and the direct costs of treating urinary stones increased by 49% and $2.5 million respectively. In the 65 other hospitals these figures decreased by 41% and about $2.9 million respectively.

CONCLUSIONS

Because of increased intervention rates the total cost of treating urinary stones has risen since the introduction of ESWL. The introduction of ESWL has also been associated with a shift in the use of resources for treating urinary stones to hospitals with a lithotriptor. The reasons for the increased intervention rates are unknown. However, given the possibility of negative health effects and the increased costs, studies to determine whether the increased rates improve health outcomes are warranted.

Biomechanical performance of spinal manipulation therapy by newly trained vs. practicing providers: does experience transfer to unfamiliar procedures?

OBJECTIVE

To examine the differences in predefined biomechanical parameters of spinal manipulation using a single method common to the training of both novice and expert manipulators.

DESIGN

Analytic Cohort Study.

PARTICIPANTS

Fifteen novice manipulators and fifteen experienced physicians provided 2 applications of spinal manipulation therapy (SMT) to 15 healthy, male student volunteers. Assignment of volunteers was randomized, and the order of the first interaction with the manipulators was determined by coin toss and then inverted for the second.

INTERVENTION

The bilateral transverse-thenar thoracic maneuver was selected from the diversified system of treatment to be used as the test procedure. Selection was guided by mechanical simplicity. SMT was applied at the physician's discretion to the region of T3-T10. Standard informed consent procedures were followed.

MAIN OUTCOME MEASURES

Preload force, rise rate of thrust and thrust force were selected as prospective primary outcome measures. Secondary descriptive measures included impulse, rise time, downward incisural point (DIP), fall time, total force, force components and direction cosines.

RESULTS

Both novice and experienced manipulators were familiar with the transverse-thenar procedure, but only three of the experienced manipulators professed common use of it. Mean values for primary outcomes were all higher for the experienced participants; however, no statistically significant differences were found.

DISCUSSION

Differences are presumed to exist between novice and experienced manipulators, as evidenced by measurement of arbitrarily selected thoracic and lumbar SMT. However, no systematic differences were found when the manipulators have a similar lack of practice experience specific to the test procedure. These results suggest the importance of regular use in developing skill of performance.

Comparison of 1.5 Tesla and 0.35 Tesla field strength magnetic resonance imaging scans in the morphometric evaluation of the lumbar intervertebral foramina

OBJECTIVE

To compare magnetic resonance imaging (MRI) scans obtained from 1.5 Tesla (T) MRI units with scans obtained from 0.35T MRI units in the morphometric evaluation of the lumbar intervertebral foramina (IVF).

DESIGN

Three dimensions of lumbar IVFs were measured on a cadaveric lumbar spine by using Vernier calipers. The spine was embedded in gelatin to simulate soft tissue and scanned twice in a 1.5T MRI unit (3-mm and 5-mm slice thicknesses) and once in a 0.35T MRI unit (5-mm slice thickness). Measurements from the scans were made independently by three observers. The results obtained from the two units were compared to the actual IVF size (as measured by calipers) and to one another.

RESULTS

The greatest superior-to-inferior distance had the strongest statistically significant correlation to the actual cadaver measurements for both the 0.35T and 1.5T imaging units [r = 0.986 (0.35T); r = 0.985 (1.5T at 3 mm) and r = 0.981 (1.5T at 5 mm); p < .0001 in all cases]. Mean differences and standard errors were minimal between measurements made from MRI scans of both 1.5T and 0.35T units and measurements made directly from the cadaveric spine.

CONCLUSION

Both imaging units produced images that accurately depicted the actual size of the IVF. The MRI units of 0.35T field strength produced images of high morphometric accuracy. In addition, the potential for side effects and the operating costs are less with 0.35T units. Therefore, 0.35T MRI units may be a prudent choice as a clinical and research imaging tool in the evaluation of the lumbar IVF.

Manipulative therapy versus education programs in chronic low back pain

STUDY DESIGN

A randomized trial was conducted on a representative sample of patients with untreated low back pain lasting 7 weeks or longer, or having more than 6 episodes in 12 months.

OBJECTIVES

To contrast the effectiveness of manipulation, a manipulation mimic, and a back education program. Methodologic criticisms of earlier studies were addressed.

SUMMARY OF BACKGROUND DATA

Published meta-analyses suggest clinical benefit from manipulation for acute patients. Data are inconclusive for patients having symptoms for longer than 1 month.

METHODS

A total of 1267 consecutive patients were screened. Block randomization was used to assign 209 qualifying patients to treatment groups. Self-reported pain and activity tolerance served as primary outcome measures. Patients were assessed at enrollment, after 2 weeks of treatment, and again after 2 weeks without treatment. Multiple teams conducted recruitment, randomization, assessment, treatment, and data analysis independently without sharing information. Treatments were carefully described, monitored, and balanced for physician attention and physical contact effects.

RESULTS

A total of 81.3% of subjects completed the study. Confounding factors and missing data were identified in approximately 20% of those completing the final follow-up. Analysis of the remaining data was carried out. A strong time effect under treatment was observed. Greater improvement was noted in pain and activity tolerance in the manipulation group. Immediate benefit from pain relief continued to accrue after manipulation, even for the last encounter at the end of the 2-week treatment interval.

CONCLUSION

Time is a strong ally of the low back pain patient. In human terms, however, there appears to be clinical value to treatment according to a defined plan using manipulation even in low back pain exceeding 7 weeks' duration.

Can our health services be saved by technology evaluation? The Quebec experience

The finances to support our health services at their present level are lacking, and much of the shortage is due to new health technologies. Through the utilisation of technology assessment (TA), it is hoped that we may be able to eliminate useless technologies and that the money so saved will allow us to maintain our health care services intact. Such hopes are exaggerated. The uses and limitations of TA are reviewed in the light of recent experience gained with the Conseil d'évaluation des technologies du Québec. Technology assessment has only limited value in exposing ineffective technologies. More often, it can illuminate inappropriate use of technologies. However, its real value lies elsewhere, namely in making difficult choices between different technologies. An example is the choice between expensive, low osmolar contrast media in radiology and the cheaper, high osmolar material which causes more frequent reactions. Credible estimates of how much benefit will result from the commitment of how many extra dollars can facilitate such decisions. However, the user must clearly understand the limitations of cost-effectiveness estimates, which should never be used for policy purposes without full knowledge of all the qualifiers on which the estimates depend.

Value of routine preoperative chest x-rays: a meta-analysis

The purpose of this study was to estimate the frequency with which routine postoperative chest x-rays lead to clinically relevant new information. All articles in English, French and Spanish relating to routine chest radiography in North American or European populations were reviewed, using the Medline database and references listed in reviews and periodicals published from 1966 to 1992, inclusive. Twenty-one reports which supplied sufficient information were included for meta-analysis. On average, abnormalities were found in 10% of routine preoperative chest films. In only 1.3% of films were the abnormalities unexpected, i.e., were not already known or would not otherwise have been detected (95% CI: 0 to 2.8%). These findings were of sufficient importance to cause modification of management in only 0.1% (95% CI: 0 to 0.6%). The frequency with which the new information influenced health could not be estimated. Assuming only the direct cost to the health care system of each radiograph ($23), each finding which influenced management in any way would cost $23,000. It is concluded that in North American or European populations when a reliable history and a clinical examination are carried out, the cost of this test is so high relation to the clinical information provided that it is no longer justifiable.

Clinical methodologies and incidence of appropriate statistical testing in orthopaedic spine literature. Are statistics misleading?

An analysis of 300 randomly drawn orthopaedic spine articles, published between 1970 and 1990, was performed to assess the quality of biostatistical testing and research design reported in the literature. Of the 300 articles, 269 dealt with topics of an experimental nature, while 31 documented descriptive studies. Statistical deficiencies were identified in 54.0% of the total articles. Conclusions drawn as the result of misleading significance values occurred in 124 experimental studies (46%) while 96 failed to document the form of analysis chosen (35.7%). Statistical testing was not documented in 34 studies (12.6%), while 20 (7.4%) employed analyses considered inappropriate for the specific design structure.

The effect of coffee consumption on serum cholesterol levels

OBJECTIVE

Studies investigating the association of coffee consumption and serum cholesterol levels report conflicting results. In an attempt to resolve this controversy, we reviewed the literature to answer the question: Is there a true positive association between coffee consumption and serum cholesterol levels?

DATA SOURCES

A Medline database search dating back to 1965 was utilized. Key words used in the search were coffee, caffeine and cholesterol. Cholesterol was expanded to include lipoproteins and LDL-, HDL- and VLDL-cholesterol. All articles that presented cholesterol data in association with coffee consumption were examined for references missed by Medline. Recently published articles were located by a hand search through Current Contents and the latest monthly editions of Index Medicus.

STUDY SELECTION

Three reviewers made the decision to include all publications that met the following criteria: a) reported original experimental results; b) reported total serum cholesterol levels; and c) were published in peer-reviewed journals.

DATA EXTRACTION

Two to four articles were read and analyzed each week in chronological order. Independent data extraction was performed by three reviewers, who then met as a group once a week to cross-check the analyses.

DATA SYNTHESIS

A trend, representing the association between coffee consumption and serum cholesterol, was calculated for each study. The trend was based on the percent difference in cholesterol values between subjects drinking four or more cups of coffee per day in comparison to those drinking zero or less than one cup of coffee each day. In order to compare studies that reported different cup sizes and different levels of intake, weighted mean cholesterol levels were calculated. In studies discussing the data in terms of correlations, trends were established according to the r values provided by the authors.

CONCLUSIONS

The majority of studies demonstrated a positive trend in at least one subpopulation of their subjects, indicating that serum cholesterol levels increase with increasing coffee consumption. Stronger trends were seen among subjects drinking boiled coffee than in those drinking filtered, decaffeinated or instant coffee. However, most studies were not randomized clinical trials, and results can be countered by a number of biases prevalent in the studies, indicating the need for additional well-designed investigations to resolve remaining issues.

A comparison of outcome measures for use with back pain patients: results of a feasibility study

OBJECTIVE

To compare the reliability, validity and change in patient clinical status over time with treatment for six potential outcome questionnaires in a defined population of patients.

SETTING

Physician based, multidoctor teaching practice.

PATIENTS

Three hundred thirty-five consecutive patients presenting with new complaints were solicited. One hundred eighty-six agreed to participate.

INTERVENTIONS

The six questionnaires being studied were administered to each of the participants on three separate occasions. They were: a) prior to clinical evaluation for their chief complaint, b) immediately after clinical evaluation and before treatment and c) 6 wk later.

MEASUREMENTS

Each instrument was scored following the prescribed methods of interpretation from the original literature describing it. Results were submitted for analysis by Pearson correlation and two-way analysis of variance as appropriate.

MAIN RESULTS

Differences were found in the mean value of the modified Zung with respect to both gender and time. An unexpected drop in patients' somatic perceptions in association with the process of clinical evaluation was found for the Modified Somatic Pain Questionnaire. Overall, the Oswestry and Visual Analogue Pain Scale were the most reliable and responsive to clinical change for musculoskeletal disorders.

CONCLUSIONS

This investigation demonstrated substantial differences in the validity and reliability of commonly referenced self-administered instruments for quantifying patient perceptions of pain and disability. The Oswestry and Visual Analogue Pain Scale were both more reliable and valid than other instruments.

The reuse of hemodialyzers: an assessment of safety and potential savings

OBJECTIVE

To evaluate the safety and potential cost savings of hemodialyzer reuse.

DATA SOURCES

All English and French articles published from 1960 to 1991 related to hemodialyzer reuse (retrieved through an Index Medicus and MEDLINE search [corrected]), the indexes of eight North American journals from 1960 onward, conference proceedings, association guidelines, and US and Canadian laws and regulations.

RESULTS

For health care personnel the reuse of hemodialyzers did not entail any increased risk of infection or exposure to toxic substances if proper control measures were taken. For patients there was no evidence to suggest any excess risk of complications or death as long as precise and appropriate procedures are observed. The "first-use syndrome" can be prevented and should no longer be considered as a reason to favour reuse. A cost-minimization analysis indicated that five uses might save up to $3629 per patient yearly. Thus, the adoption of a policy of reuse in Canada for all eligible patients undergoing long-term hemodialysis could result in direct savings of about $5.8 to $8.9 million per year.

CONCLUSION

The health risks associated with hemodialyzer reuse can be reduced to acceptable levels through the rigorous observance of proper quality-assurance and quality-control measures and the use of automated reconditioning equipment. Such a policy could achieve modest savings for the health care system. A decision to reuse should be formally adopted by the institution and accompanied by a precise definition of the standards of quality assurance and control.

The Hmax/Mmax ratio as an outcome measure for acute low back pain

OBJECTIVE

To evaluate the use of the Hmax/Mmax (H/M) ratio as an outcome measure for acute low back pain and to determine the change of this ratio in acute low back pain patients treated with spinal manipulation.

DESIGN

Randomized clinical trial.

SETTING

Chiropractic college teaching clinic.

PATIENTS

Thirty-six patients with acute low back pain (pain of less than 2 wk duration) were referred by clinicians of the teaching clinic. Eligibility criteria for inclusion into the study consisted of the following: a score of eight or more on the Oswestry questionnaire, 33 mm or greater on a 100-mm visual analog scale, no involvement in litigation related to the low back pain complaint, patient not pregnant and no physical or electrodiagnostic signs of nerve root entrapment.

INTERVENTIONS

The patients were randomly assigned to either a treatment or control group. The treatment group (n = 17) received treatment deemed appropriate by the clinician as long as it included a side-lying manipulation to the appropriate level. The control group (n = 19) received detuned ultrasound, application of a cold pack and 15-30 sec of very gentle soft tissue massage. Patients were treated three to five times over a period of 10 days and were subsequently reevaluated.

MEASUREMENTS

The Hmax/Mmax ratio was calculated from the results of electrodiagnostic testing of the posterior tibial nerve. Extension/flexion ratio of the trunk musculature, Oswestry score and Visual Analog Scale score were also measured.

MAIN RESULTS

The mean difference between H/M ratios pre- and postintervention for the group treated by chiropractic methods was -0.101 on the left and -0.117 on the right. The mean difference for the control group was 0.038 on the left and 0.036 on the right. Although not statistically significant, trends suggest that at the time of final assessment, the group receiving chiropractic care had improved more than the control group.

CONCLUSIONS

The H/M ratio was found to be within normal limits in subjects with acute low back pain. The H/M ratio showed greater change in the group which received spinal manipulation, but the change was subtle. The results indicate that the H/M ratio may be of limited value in clinical practice.