Outpatient oral anticancer agent utilization and costs in Manitoba from 2003 to 2016: a population-based study

INTERVENTION

In April 2012, the Manitoba Home Cancer Drug Program (HCDP) was introduced to allow 100% coverage for eligible oral anticancer agents (OAA) and supportive medications for Manitobans with cancer requiring these therapies.

RESEARCH QUESTIONS

What is the extent of use and cost of OAAs among outpatients in Manitoba from 2003/04 to 2015/16? Did the HCDP change OAA user and prescription patterns?

METHODS

This was a retrospective, population-based study using administrative data to measure the prevalence of drug utilization over time and the impact of HCDP on OAA use and prescriptions using generalized linear models. Manitobans with cancer who filled an OAA or supportive medication covered by HCDP from 2003/04 to 2015/16 were included.

RESULTS

This study included 22,393 people with cancer who filled an OAA prescription. The prevalence of OAA use increased from 222 per 100,000 to 328 per 100,000 from 2003/04 to 2015/16. Hormone therapy for breast cancer was the most common class of OAA used (increased from 154 per 100,000 to 231 per 100,000). We observed a 2.6-fold decrease in the prevalence of oral alkylating agents and a 10.7-fold increase in the prevalence of protein kinase inhibitors during the study period. The total cost of targeted OAAs per year for all Manitobans with cancer increased from $1.8 million to $19 million.

CONCLUSION

We observed an increase in OAA prevalence and the cost of oral targeted chemotherapy is high. Our findings underline the need for addressing these high-cost medications in future developments of a national drug program.

Fueling of a marine-terrestrial ecosystem by a major seabird colony

Seabirds redistribute nutrients between different ecosystem compartments and over vast geographical areas. This nutrient transfer may impact both local ecosystems on seabird breeding islands and regional biogeochemical cycling, but these processes are seldom considered in local conservation plans or biogeochemical models. The island of Stora Karlsö in the Baltic Sea hosts the largest concentration of piscivorous seabirds in the region, and also hosts a large colony of insectivorous House martins Delichon urbicum adjacent to the breeding seabirds. We show that a previously reported unusually high insectivore abundance was explained by large amounts of chironomids—highly enriched in δ¹⁵N—that feed on seabird residues as larvae along rocky shores to eventually emerge as flying adults. Benthic ammonium and phosphate fluxes were up to 163% and 153% higher close to the colony (1,300 m distance) than further away (2,700 m) and the estimated nutrient release from the seabirds at were in the same order of magnitude as the loads from the largest waste-water treatment plants in the region. The trophic cascade impacting insectivorous passerines and the substantial redistribution of nutrients suggest that seabird nutrient transfer should be increasingly considered in local conservation plans and regional nutrient cycling models.

Impact heat driven volatile redistribution at Occator crater on Ceres as a comparative planetary process

Hydrothermal processes in impact environments on water-rich bodies such as Mars and Earth are relevant to the origins of life. Dawn mapping of dwarf planet (1) Ceres has identified similar deposits within Occator crater. Here we show using Dawn high-resolution stereo imaging and topography that Ceres' unique composition has resulted in widespread mantling by solidified water- and salt-rich mud-like impact melts with scattered endogenic pits, troughs, and bright mounds indicative of outgassing of volatiles and periglacial-style activity during solidification. These features are distinct from and less extensive than on Mars, indicating that Occator melts may be less gas-rich or volatiles partially inhibited from reaching the surface. Bright salts at Vinalia Faculae form thin surficial precipitates sourced from hydrothermal brine effusion at many individual sites, coalescing in several larger centers, but their ages are statistically indistinguishable from floor materials, allowing for but not requiring migration of brines from deep crustal source(s).

Association between Tumor Acidity and Hypervascularity in Human Gliomas Using pH-Weighted Amine Chemical Exchange Saturation Transfer Echo-Planar Imaging and Dynamic Susceptibility Contrast Perfusion MRI at 3T

BACKGROUND AND PURPOSE

Acidification of the tumor microenvironment from abnormal metabolism along with angiogenesis to meet metabolic demands are both hallmarks of malignant brain tumors; however, the interdependency of tumor acidity and vascularity has not been explored. Therefore, our aim was to investigate the association between pH-sensitive amine chemical exchange saturation transfer echoplanar imaging (CEST-EPI) and relative cerebral blood volume (CBV) measurements obtained from dynamic susceptibility contrast (DSC) perfusion MRI in patients with gliomas.

MATERIALS AND METHODS

In this retrospective study, 90 patients with histologically confirmed gliomas were scanned between 2015 and 2018 (median age, 50.3 years; male/female ratio = 59:31). pH-weighting was obtained using chemical exchange saturation transfer echo-planar imaging estimation of the magnetization transfer ratio asymmetry at 3 ppm, and CBV was estimated using DSC-MR imaging. The voxelwise correlation and patient-wise median value correlation between the magnetization transfer ratio asymmetry at 3 ppm and CBV within T2-hyperintense lesions and contrast-enhancing lesions were evaluated using the Pearson correlation analysis.

RESULTS

General colocalization of elevated perfusion and high acidity was observed in tumors, with local intratumor heterogeneity. For patient-wise analysis, median CBV and magnetization transfer ratio asymmetry at 3 ppm within T2-hyperintense lesions were significantly correlated (R = 0.3180, P = .002), but not in areas of contrast enhancement (P = .52). The positive correlation in T2-hyperintense lesions remained within high-grade gliomas (R = 0.4128, P = .001) and in isocitrate dehydrogenase wild-type gliomas (R = 0.4300, P = .002), but not in World Health Organization II or in isocitrate dehydrogenase mutant tumors. Both magnetization transfer ratio asymmetry at 3 ppm and the voxelwise correlation between magnetization transfer ratio asymmetry and CBV were higher in high-grade gliomas compared with low-grade gliomas in T2-hyperintense tumors (magnetization transfer ratio asymmetry, P = .02; Pearson correlation, P = .01). The same trend held when comparing isocitrate dehydrogenase wild-type gliomas and isocitrate dehydrogenase mutant gliomas (magnetization transfer ratio asymmetry, P = .04; Pearson correlation, P = .01).

CONCLUSIONS

A positive linear correlation between CBV and acidity in areas of T2-hyperintense, nonenhancing tumor, but not enhancing tumor, was observed across patients. Local heterogeneity was observed within individual tumors.

Prescription medication use during pregnancies that resulted in births and abortions (2001-2013): A retrospective population-based study in a Canadian population

We aimed to describe medication use in pregnancies that resulted in births and abortions, as well as use after a pregnancy-related visit to characterize the receipt of medication after knowledge of pregnancy. Abortions included both spontaneous and induced abortions. Rates of medication use among women with a pregnancy outcome (2001–2013) were described using the Manitoba Population Research Data Repository at the Manitoba Centre for Health Policy. Use was determined as ≥ 1 prescription filled during pregnancies that resulted in births (livebirth/stillbirth) and abortions. Rates were calculated at any time during pregnancy and after a pregnancy-related visit. Rates were additionally characterized by risk in pregnancy using Briggs classification (2017). Of 174,848 birth pregnancies, overall 64.9% filled ≥ 1 prescription during pregnancy (a significant increase from 62.3% to 68.8% from 2001–2013, p<0.0001); 55.4% filled ≥ 1 prescription after a pregnancy-related visit. Of 71,967 abortions, 44.7% filled ≥ 1 prescription (a significant increase from 42.6% to 46.8% from 2001–2013, p<0.0001). Only 3.7% of birth pregnancies had at least one prescription for a contraindicated medication (according to Briggs classification), whereas 10.8% of abortions filled a prescription for a contraindicated medication. The most common drugs used in pregnancy were amoxicillin, doxylamine, codeine combinations, nitrofurantoin, cephalexin, salbutamol and ranitidine. Fewer women filled prescriptions for undesirable medications according to Briggs classification during pregnancy after a pregnancy-related visit.

Psychotropic Drug Use before, during, and after Pregnancy: A Population-Based Study in a Canadian Cohort (2001-2013)

OBJECTIVE

To describe the extent of increase in use and the rate of continuation versus discontinuation of psychotropic agents before, during, and after pregnancy.

METHODS

Rates of psychotropic use (antidepressants, anxiolytic/sedative-hypnotics, antiepileptics, antipsychotics, lithium, stimulants) among women with a hospital-recorded pregnancy outcome were assessed using databases at the Manitoba Centre for Health Policy. Rate of use was defined as ≥1 prescription over the total number of pregnancies in the 3-12 months before pregnancy, 0-3 months before pregnancy, during pregnancy, or 3 months after pregnancy. Continued use was defined as ≥2 prescriptions with gap ≤14 days. Poisson regression was used to analyze trends.

RESULTS

Over the study period, a psychotropic drug was used before, during, or after pregnancy in 41,923 of 224,762 pregnancies. From 2001 to 2013, psychotropic use increased 1.5-fold from 11.1% to 16.2% ( p < 0.0001) in the 3-12 months before pregnancy, 1.6-fold from 6.4% to 10.5% ( p < 0.0001) in the 3 months before pregnancy, 1.8-fold from 3.3% to 6.0% ( p < 0.0001) during pregnancy, and 1.5-fold from 6.2% to 9.5% ( p < 0.0001) in the 3 months postpartum. Among the 13,579 women who received at least 1 psychotropic agent in the 3 months prior to pregnancy, 38.5% stopped the agent prior to pregnancy and only 10.3% continued use throughout pregnancy. Continued use throughout pregnancy was higher (56.9%) among the 6693 women who received at least 2 prescriptions for a psychotropic agent and were at least 80% adherent in the 3 months prior to pregnancy.

CONCLUSION

The use of psychotropic agents increased over 12 years. The safety of continuing versus discontinuing these agents during pregnancy remains uncertain, but we observed a decrease in psychotropic drug use during the pregnancy period.

Sex differences in the risk of receiving potentially inappropriate prescriptions among older adults

Objectives: to measure sex differences in the risk of receiving potentially inappropriate prescription drugs and to examine what are the factors that contribute to these differences.

Design: a retrospective cohort study.

Setting: community setting of British Columbia, Canada.

Participants: residents of British Columbia aged 65 and older (n = 660,679).

Measurements: we measured 2013 period prevalence of prescription dispensations satisfying the American Geriatrics Society's 2012 version of the Beers Criteria for potentially inappropriate medication use in older adults. We used logistic regressions to test for associations between this outcome and a number of clinical and socioeconomic factors.

Results: a larger share of women (31%) than of men (26%) filled one or more potentially inappropriate prescription in the community. The odds of receiving potentially inappropriate prescriptions are associated with several clinical and socioeconomic factors. After controlling for those factors, community-dwelling women were at 16% higher odds of receiving a potentially inappropriate prescription than men (adjusted odds ratio = 1.16, 95% confidence interval = 1.12–1.21). Much of this sex difference stemmed from women's increased odds of receiving potentially inappropriate prescriptions for benzodiazepines and other hypnotics, for tertiary tricyclic antidepressants and for non-selective NSAIDs.

Conclusion: there are significant sex differences in older adults' risk of receiving a potentially inappropriate prescription as a result of complex intersections between gender and other social constructs. Appropriate responses will therefore require changes in the information, norms and expectations of both prescribers and patients.

Increasing Capacity for Experiential Rotations for Pharmacy Learners: Lessons Learned from a Multisite Teaching Hospital

-

The impact of opioid prescription dose and duration during a workers compensation claim, on post-claim continued opioid use: A retrospective population-based study

BACKGROUND

Workers Compensation Board (WCB) recipients are a group commonly prescribed opioids.

METHODS

We explored factors influencing post-claim opioid dose and duration by linking data from 22,451 claims with the Manitoba Center for Population Health registry.

RESULTS

On average, the WCB paid for 94.55% of opioids prescribed during a claim. The amount paid for by the WCB varied significantly by total opioids prescribed. The main predictors of high opioid dosage (120 + morphine equivalents (ME)/day) during the first year post-claim (logistic regression), and of longer post-claim opioid usage (survival analysis), included opioid dosage during the final month of the claim both paid for and not paid for by the WCB.

CONCLUSIONS

Amongst low dose opioid claims, the WCB covers most opioids prescribed. Higher opioid dose WCB recipients are often prescribed opioids not covered by the WCB. Both opioids paid for and not paid for by the WCB are associated with post-claim opioid use.

Proton pump inhibitors and the risk of adverse cardiac events

Background

Recent evidence suggests that proton pump inhibitors (PPIs) might be linked with adverse cardiac events, but a causal relationship is unproven.

Methods

We applied the self-matched case series method to two studies using population-based health care data from Ontario, Canada between 1996 and 2008. The first included subjects aged 66 years or older hospitalized for acute myocardial infarction within 12 weeks following initiation of PPI, while the second included subjects hospitalized for heart failure. In both studies we designated the primary risk interval as the initial 4 weeks of therapy and the control interval as the final 4 weeks. To test the specificity of our findings we examined use of histamine H2 receptor antagonists and benzodiazepines, drugs with no plausible causal link to adverse cardiac events.

Results

During the 13-year study period, we identified 5550 hospital admissions for acute myocardial infarction and 6003 admissions for heart failure within 12 weeks of commencing PPI therapy. In the main analyses, we found that initiation of a PPI was associated with a higher risk of acute myocardial infarction (odds ratio 1.8; 95% confidence interval 1.7 to 1.9) and heart failure (odds ratio 1.8; 95% confidence interval 1.7 to 1.9). However, secondary analyses revealed similar risk estimates histamine H2 receptor antagonists and benzodiazepines, drugs with no known or suspected association with adverse cardiac events.

Conclusion

PPIs are associated with a short-term risk of adverse cardiac events, but similar associations are seen with other drugs exhibiting no known cardiac toxicity. Collectively these observations suggest that the association between PPIs and adverse cardiac events does not represent reflect cause-and-effect.

Prescribing of psychotropic medications to the elderly population of a Canadian province: a retrospective study using administrative databases

Background. Psychotropic medications, in particular second-generation antipsychotics (SGAs) and benzodiazepines, have been associated with harm in elderly populations. Health agencies around the world have issued warnings about the risks of prescribing such medications to frail individuals affected by dementia and current guidelines recommend their use only in cases where the benefits clearly outweigh the risks. This study documents the use of psychotropic medications in the entire elderly population of a Canadian province in the context of current clinical guidelines for the treatment of behavioural disturbances.

Methods. Prevalent and incident utilization of antipsychotics, benzodiazepines and related medications (zopiclone and zaleplon) were determined in the population of Manitobans over age 65 in the time period 1997/98 to 2008/09 fiscal years. Comparisons between patients living in the community and those living in personal care (nursing) homes (PCH) were conducted. Influence of sociodemographic characteristics on prescribing was assessed by generalized estimating equations. Non-optimal use was defined as the prescribing of high dose of antipsychotic medications and the use of combination therapy of a benzodiazepine (or zopiclone/zaleplon) with an antipsychotic. A decrease in intensity of use over time and lower proportions of patients treated with antipsychotics at high dose or in combination with benzodiazepines (or zopiclone/zaleplon) was considered a trend toward better prescribing. Multiple regression analysis determined predictors of non-optimal use in the elderly population.

Results. A 20-fold greater prevalent utilization of SGAs was observed in PCH-dwelling elderly persons compared to those living in the community. In 2008/09, 27% of PCH-dwelling individuals received a prescription for an SGA. Patient characteristics, such as younger age, male gender, diagnoses of dementia (or use of an acetylcholinesterase inhibitor) or psychosis in the year prior the prescription, were predictors of non-optimal prescribing (e.g., high dose antipsychotics). During the period 2002/3 and 2007/8, amongst new users of SGAs, 10.2% received high doses. Those receiving high dose antipsychotics did not show high levels of polypharmacy.

Conclusions. Despite encouraging trends, the use of psychotropic medications remains high in elderly individuals, especially in residents of nursing homes. Clinicians caring for such patients need to carefully assess risks and benefits.

Taking aim at medical identity theft. Document security key element to comply with government regulations

Sensitive paper documents, such as patient records, customer data, and legal information, must be securely stored and destroyed when no longer needed. This is not only a good business practice that reduces costs and protects reputations, but also a legal and regulatory imperative. According to some experts, medical identity theft is the fastest-growing form of identity theft in North America. The Federal Trade Commission's Red Flags Rule, due to take effect June 1, 2010, requires banks; credit card companies; and, in some situations, retailers, hospitals, insurance companies, health clinics, and other organizations to store confidential personal information that can expose consumers to significant identity theft risks. This also includes healthcare providers and other organizations that are considered creditors according to their billing/payment procedures. This article highlights the steps healthcare providers must take to ensure data security.

Drug-related problems in patients undergoing elective total joint arthroplasty of the hip or knee

BACKGROUND

Few studies have evaluated drug-related problems in patients undergoing elective total hip or knee arthroplasty.

OBJECTIVE

To quantify, for patients undergoing elective total joint arthroplasty, drug-related problems arising from medication orders written before or immediately after the surgery. The primary outcome was the proportion of patients with at least one drug-related problem. The secondary outcomes were the total number and descriptions of these problems, according to the patient's age and the category, type, and severity of the drug-related problem.

METHODS

From among patients who underwent elective total joint arthroplasty in a large Canadian regional health authority in 2005, 150 were randomly selected for this chart audit. Patients were included if they had been taking more than one medication before surgery. The charts were examined for drug-related problems, which were categorized according to whether the problem involved a prescription for a home medication, an order for a postoperative medication, or a potential indication for drug therapy. The problems were further described by type and potential severity.

RESULTS

Of the 146 patients whose charts were available, 116 (79.5%) had at least one drug-related problem, with a mean of 1.88 drug-related problems per patient. Of the 146 patients, 88 (60.3%) had at least one drug-related problem involving a home medication, 34 (23.3%) had problems related to postoperative orders, and 37 (25.3%) had problems related to a potential indication. The mean number of drug-related problems per patient was 2.03 for those 65 years of age or older and 1.56 for those younger than 65 years (p = 0.09); however, more of the older patients experienced at least one drug-related problem related to home medications (67% [67/100] versus 46% [21/46], p = 0.02). The most common types of problems were medication omissions, illegible drug orders, inappropriate dose or frequency, and drug-allergy interactions. Of the 275 drug-related problems identified, 147 (53.5%) were deemed potentially harmful, 78 (28.4%) required monitoring, and 50 (18.2%) were considered not harmful.

CONCLUSIONS

In this study, patients who underwent total joint arthroplasty experienced many drug-related problems. Pharmacists may have opportunities to optimize patient care by identifying, resolving, and preventing drug-related problems in this patient population.

Breadth, Depth and Agreement among Provincial Formularies in Canada

BACKGROUND

Previous studies have concluded that there is significant variation in drug coverage across Canadian provinces because conventional measures of inter-rater reliability for formulary listings are low. We sought to investigate whether conventional methods are appropriate for formulary concordance measurement by testing the hypotheses that (a) conventionally measured variations in provincial formularies are driven by disagreement over large numbers of drugs that represent very small segments of the market and (b) patterns in coverage levels and agreement across therapeutic categories might provide evidence of "potentially legitimate" variation in provincial formularies.

METHODS

We studied December 2006 formulary listings for general pharmacare programs in all but the smallest Canadian province. We characterized formularies in terms of the simple percentage of all available drugs that were listed on them and by a similar percentage that weighted each drug by its total national retail sales during 2006. We measured agreement among formularies using conventional inter-rater reliability scores (Kappa statistics) and a simple coverage-agreement measure.

RESULTS

Provincial formularies studied here listed between 55% and 73% of the 796 drugs analyzed. When formulary listings were weighted by national retail sales, the measure of formulary coverage exceeded 86% in all provinces studied. Conventional inter-rater reliability scores (Kappa statistics) indicate that coverage agreement among most provincial formularies was low to moderate; however, drugs that were listed on all nine provincial formularies studied accounted for 77% of total retail spending in Canada. When analyzed by therapeutic category, the extent of coverage offered was relatively consistent across provinces in all but three leading categories: anti-migraine drugs, anti-dementia drugs and sedatives.

CONCLUSION

While variations in coverage for specific drug classes and drug products remain important areas for investigation and policy consideration, Canada is currently operating with a significant "implicit national formulary" by way of the fact that provincial formularies independently yet mutually list most of the top-selling medicines in the marketplace.

Characterizing early prescribers of newly marketed drugs in Canada: a population-based study

BACKGROUND

The diffusion of innovations model proposes that early adopters of innovation influence others. This study was undertaken to determine if early prescribers and users of newly marketed drugs had different sociodemographic and professional characteristics as compared to majority and late users and prescribers.

METHODS

After market availability in Manitoba, Canada, of celecoxib, alendronate, clopiodogrel and pantoprazole, time to first prescriptions was determined. Early, majority and late adopters of the new drug were characterized by this diffusion time. The prescription, health and prescriber records were compared across adopter categories. The likelihood of being an early or late prescriber or user of the new medications according to patient demographic characteristics, physician factors (specialty and place of training) and neighborhood income was determined with polytomous logistic regression.

RESULTS

Celecoxib demonstrated a much more rapid uptake into routine use than the other drugs. More than 300 Manitoba physicians prescribed celecoxib within two weeks of market availability. Early prescribers of celecoxib were more likely than majority prescribers to be general practitioners (OR = 1.81, 95%CI: 1.40-2.35) and have hospital affiliations (OR = 1.35, 95%CI: 1.03-1.77). Early users of celecoxib were more likely than the majority to have arthritic conditions, have a high income and have paid out-of-pocket for their prescription. For alendronate, clopidogrel and pantoprazole, only prescription drug coverage predicted adopter category. Early prescribers of one new drug were not early prescribers of the other new drugs.

CONCLUSION

No common group of patients or physicians who were early prescribers or users of all four medications was described.

Use of celecoxib immediately post marketing in Canada: acute or chronic pain?

OBJECTIVES

The diffusion of innovations theory suggests that early users of innovations influence others. This study was undertaken to apply the diffusion of innovations theory to the prescribing of celecoxib and to determine if prescriber and patient characteristics differed amongst early use of celecoxib for acute pain versus chronic musculoskeletal conditions.

METHODS

Using Manitobaâs population-based prescription and health care databases, diffusion time from market availability to first prescription for celecoxib was determined for each prescriber. The diffusion of prescribing curves for celecoxib in acute pain versus chronic musculoskeletal conditions were compared. Separately for acute and chronic conditions, the likelihood of being an early or late prescriber or user of celecoxib was determined according to physician factors (specialty and place of training) and patient demographics. This multivariate analysis was completed using polytomous logistic regression, with majority prescribers as the reference.

RESULTS

The use of celecoxib for chronic musculoskeletal conditions demonstrated faster diffusion than for acute pain. The majority of early use of celecoxib was for chronic conditions; however 36% of first prescriptions were for acute pain, including the treatment of back pain and injuries. Early prescribers of celecoxib for acute pain were more likely than majority prescribers to be general practitioners (OR = 2.24, 95%CI: 1.53-3.29) and have hospital affiliations (OR=1.54, 95%CI: 1.04-2.27). Early users of celecoxib for chronic conditions were less likely to be low income (OR=0.56, 95%CI: 0.35-0.91).

CONCLUSIONS

Immediately after market release in Canada, celecoxib was commonly prescribed for the treatment of acute pain; these prescriptions were associated with general practitioners and hospital affiliation status.

The DNA sequence and biological annotation of human chromosome 1

The reference sequence for each human chromosome provides the framework for understanding genome function, variation and evolution. Here we report the finished sequence and biological annotation of human chromosome 1. Chromosome 1 is gene-dense, with 3,141 genes and 991 pseudogenes, and many coding sequences overlap. Rearrangements and mutations of chromosome 1 are prevalent in cancer and many other diseases. Patterns of sequence variation reveal signals of recent selection in specific genes that may contribute to human fitness, and also in regions where no function is evident. Fine-scale recombination occurs in hotspots of varying intensity along the sequence, and is enriched near genes. These and other studies of human biology and disease encoded within chromosome 1 are made possible with the highly accurate annotated sequence, as part of the completed set of chromosome sequences that comprise the reference human genome.

Control of immunoglobulin isotype production by porcine B-cells cultured with cytokines

Cytokines regulate immunoglobulin (Ig) isotype production following the Th1/Th2 paradigm, derived from studies of inbred mice. In pigs, it is not known which, if any, Ig isotypes may reflect a Th1/Th2 response. To evaluate this, purified porcine CD21(+) B-cells were co-cultured with Staphylococcus aureus Cowan strain 1 or Escherichia coli lipopolysaccharide as B-cell mitogens together with recombinant human IL-2, and recombinant porcine (rp) interferon (IFN)-gamma, IL-12 or IL-10. While the mitogens increased B-cell proliferation, cytokines had no additional effect. A quantitative competitive enzyme-immuno assay was used to measure concentrations of porcine IgM, IgG(1) and IgG(2) in B-cell culture supernatants. In vitro, porcine B-cells produced IgG(2), 106 +/- 17.3 microg/ml; IgG(1) 107 +/- 38.3 microg/ml and IgM 25.6 +/- 8.45 microg/ml. In some individuals, Th1 cytokines such as rpIFN-gamma and IL-12, enhanced IgG(2) in the face of low concentrations of IgG(1). Furthermore, individual responses, in some cases, tended to be diametrically opposed, reminiscent of previously documented categorical immune responses in pigs such that some individuals produced high concentrations of IgG(1) in response to the various doses of rp cytokines, while others produced lower concentrations. Pigs may generate a high IgG(1):IgG(2) ratio in response to rpIL-10, and possibly to other Th2-associated cytokines. However, B-cell response to rp cytokines in vitro exhibits marked variation by pig, a feature that is likely a function of highly variable individual genotypes and their interaction with complex environments.

The genome of the natural genetic engineer Agrobacterium tumefaciens C58

The 5.67-megabase genome of the plant pathogen Agrobacterium tumefaciens C58 consists of a circular chromosome, a linear chromosome, and two plasmids. Extensive orthology and nucleotide colinearity between the genomes of A. tumefaciens and the plant symbiont Sinorhizobium meliloti suggest a recent evolutionary divergence. Their similarities include metabolic, transport, and regulatory systems that promote survival in the highly competitive rhizosphere; differences are apparent in their genome structure and virulence gene complement. Availability of the A. tumefaciens sequence will facilitate investigations into the molecular basis of pathogenesis and the evolutionary divergence of pathogenic and symbiotic lifestyles.

Gonococcal MinD affects cell division in Neisseria gonorrhoeae and Escherichia coli and exhibits a novel self-interaction

The Min proteins are involved in determining cell division sites in bacteria and have been studied extensively in rod-shaped bacteria. We have recently shown that the gram-negative coccus Neisseria gonorrhoeae contains a min operon, and the present study investigates the role of minD from this operon. A gonococcal minD insertional mutant, CJSD1, was constructed and exhibited both grossly abnormal cell division and morphology as well as altered cell viability. Western blot analysis verified the absence of MinD from N. gonorrhoeae (MinD(Ng)) in this mutant. Hence, MinD(Ng) is required for maintaining proper cell division and growth in N. gonorrhoeae. Immunoblotting of soluble and insoluble gonococcal cell fractions revealed that MinD(Ng) is both cytosolic and associated with the insoluble membrane fraction. The joint overexpression of MinC(Ng) and MinD(Ng) from a shuttle vector resulted in a significant enlargement of gonococcal cells, while cells transformed with plasmids encoding either MinC(Ng) or MinD(Ng) alone did not display noticeable morphological changes. These studies suggest that MinD(Ng) is involved in inhibiting gonococcal cell division, likely in conjunction with MinC(Ng). The alignment of MinD sequences from various bacteria showed that the proteins are highly conserved and share several regions of identity, including a conserved ATP-binding cassette. The overexpression of MinD(Ng) in wild-type Escherichia coli led to cell filamentation, while overexpression in an E. coli minD mutant restored a wild-type morphology to the majority of cells; therefore, gonococcal MinD is functional across species. Yeast two-hybrid studies and gel-filtration and sedimentation equilibrium analyses of purified His-tagged MinD(Ng) revealed a novel MinD(Ng) self-interaction. We have also shown by yeast two-hybrid analysis that MinD from E. coli interacts with itself and with MinD(Ng). These results indicate that MinD(Ng) is required for maintaining proper cell division and growth in N. gonorrhoeae and suggests that the self-interaction of MinD may be important for cell division site selection across species.

Natural killer cell frequency and function in Yorkshire pigs selectively bred for high or low antibody and cell-mediated immune response

Porcine NK cells are small to medium-size lymphocytes having a variety of functions that may include the regulation of immune response. Thus frequency and function of NK cells were examined in generations 6 and 8 (G6, G8) of pigs selectively bred for high (H) and low (L) antibody and cell-mediated immune response (CMIR). Using the monoclonal antibody 5C6 as a pan NK phenotype marker and target cell binding and lysis as assays of function, it was found that H and L immune response pigs had high and low NK cell frequency, respectively, at G6 and G8. Function of NK cells differed by line, with the control (unselected) pigs being higher (with respect to target cell binding) or similar (with respect to lytic activity) to H which were higher than the L line pigs. Frequency of NK cells after primary immunization was in significant negative correlation with antibody after secondary immunization with hen egg white lysozyme (HEWL). Therefore, simultaneous selection for antibody and CMIR altered the frequency and function of NK cells in pigs with C > or = H > L.

Role of Thr(11) in the binding of omega-conotoxin MVIIC to N-type Ca2+ channels

As replacement of Thr(11) of omega-conotoxin MVIIC with Ala significantly reduced the affinity for both N- and P/Q-type calcium channels, we examined the effect of substitution at this position with other residues. Binding assays using rat cerebellar P2 membranes showed that the affinity is in the order of Leu>Val, aminobutyric acid, Thr>Asn&z.Gt;Ser, Ala, Asp, Phe, Tyr for N-type channels and Thr>Leu, Val, aminobutyric acid, Asn, Ser>Ala&z.Gt;Asp, Phe, Tyr for P/Q-type channels, suggesting that aliphatic amino acids with longer side chains are favorable for block of N-type channels. The effects of substitution were examined electrophysiologically in BHK cells expressing N-type Ca2+ channels. Inhibition of Ba2+ current by the analogs did not completely correlate with binding affinity, although binding to BHK cells was comparable to rat cerebellar membranes.

Initial sequencing and analysis of the human genome

The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.

Natural killer cell frequency and function in pigs selectively bred for high or low antibody and cell-mediated immune response: response to vaccination with modified live transmissible gastroenteritis virus

Porcine NK cells are small to medium lymphocytes which are lytic for tumours and virally infected cells when co-cultured for long periods ( approximately 16 h). The frequency and function of NK cells were examined in generation 8 of pigs genetically selected for high (H), low (L), and control (C) antibody (Ab) and cell-mediated immune response (CMIR). The NK phenotype was identified using a pan-species NK-specific murine monoclonal antibody (5C6) and both binding and lysis of the NK target, K562. Vaccination with modified live transmissible gastroenteritis virus (TGEV) had no effect on blood leucocyte NK cell frequency. In interactions with K562 targets, NK cells of H and C pigs responded similarly in frequency of conjugate formation and lytic activity, while L pigs had very little or no response. Therefore, in pigs selected for high Ab and CMIR, there was no correlated enhancement of NK-cell-related traits following vaccination with TGEV, while selection for low immune response was associated with reduced NK response in pigs. This may suggest that low immune response can reflect reduced contribution of NK cells in pigs.

Binding of Ala-scanning analogs of omega-conotoxin MVIIC to N- and P/Q-type calcium channels

omega-Conotoxin MVIIC binds to P/Q-type calcium channels with high affinity and N-type channels with low affinity. To reveal the residues essential for subtype selectivity, we synthesized Ala-scanning analogs of MVIIC. Binding assays using rat cerebellar P(2) membranes suggested that Thr(11), Tyr(13) and Lys(2) are essential for binding to both N- and P/Q-type channels, whereas Lys(4) and Arg(22) are important for binding to P/Q-type channels. These results suggest that MVIIC interacts with P/Q-type channels via a large surface, in good agreement with previous observations using chimeric analogs.

Binding of six chimeric analogs of omega-conotoxin MVIIA and MVIIC to N- and P/Q-type calcium channels

Replacement of the N-terminal half of omega-conotoxin MVIIC, a peptide blocker of P/Q-type calcium channels, with that of omega-conotoxin MVIIA significantly increased the affinity for N-type calcium channels. To identify the residues essential for subtype selectivity, we examined single reverse mutations from MVIIA-type to MVIIC-type in this chimeric analog. A reverse mutation from Lys(7) to Pro(7) decreased the affinity for both P/Q- and N-type channels, whereas that from Leu(11) to Thr(11) increased the affinity for P/Q-type channels and decreased the affinity for N-type channels. The roles of these two residues were confirmed by synthesizing two MVIIC analogs in which Pro(7) and Thr(11) were replaced with Lys(7) and Leu(11), respectively.

Antibodies against the beta subunit of voltage-dependent calcium channels in Lambert-Eaton myasthenic syndrome

Lambert-Eaton myasthenic syndrome is an autoimmune disease that impairs neuromuscular transmission. Several studies suggest that neurotransmitter release is reduced by an immune response directed against the calcium channel complex of nerve terminals. The immunoglobulin G fractions from Lambert-Eaton myasthenic syndrome patients immunoprecipitate solubilized neuronal N- and P/Q-type channels and in certain cases brain, skeletal and cardiac muscle L-type channels [El Far O. et al. (1995) J. Neurochem. 64, 1696-1702; Lennon V. A. and Lambert E. H. (1989) Mayo Clin. Proc. 64, 1498-1504; Sher E. et al. (1989) Lancet ii, 640-643; Suenaga A. et al. (1996) Muscle Nerve 19, 1166-1168]. These channel immunoprecipitation assays are considered as useful for the diagnosis of this syndrome. In this study, we demonstrate that two predominant neuronal voltage-dependent calcium channel beta subunits (beta3 and beta4, of mol. wt 58,000) are general targets of Lambert-Eaton myasthenic syndrome autoantibodies. Of 20 disease sera tested, 55% were able to immunoprecipitate 35S-labeled beta subunits. All five patients affected with small-cell lung carcinoma were positive for the beta-subunit immunoprecipitation assay. Interestingly, only a fraction of the beta-subunit-positive sera was also able to immunoprecipitate N- and P/Q-type channels, suggesting that several of the beta-subunit epitopes are masked in native channels. In accordance with this observation, we found that several beta-positive sera were able to prevent the interaction between calcium channel alpha1 and beta subunits in vitro. In cases where sera were able to immunoprecipitate beta subunits, N- and P/Q-type channels, the immunoprecipitation of both channel types was either partially or entirely mediated by beta-subunit antibodies. Our results suggest that assays based on the immunoprecipitation of beta subunits can be used as an additional test to assist in the diagnosis of Lambert-Eaton myasthenic syndrome.

Binding of chimeric analogs of omega-conotoxin MVIIA and MVIIC to the N- and P/Q-type calcium channels

Despite their high sequence homology, the peptide neurotoxins omega-conotoxin MVIIA and MVIIC selectively block N- and P/Q-type calcium channels, respectively. To study the recognition mechanism of calcium channel subtypes, two chimeric analogs of omega-conotoxin MVIIA and MVIIC were synthesized by exchanging their N- and C-terminal halves. Binding assay for both N- and P/Q-type calcium channels showed that amino acid residues restricted to the N-terminal half are important for the recognition of N-type channels, whereas essential residues for P/Q-type channel recognition are widely spread over the whole omega-conotoxin molecule.

Direct interaction of the calcium sensor protein synaptotagmin I with a cytoplasmic domain of the alpha1A subunit of the P/Q-type calcium channel

Synaptotagmins are synaptic vesicle proteins containing two calcium-binding C2 domains which are involved in coupling calcium influx through voltage-gated channels to vesicle fusion and exocytosis of neurotransmitters. The interaction of synaptotagmins with native P/Q-type calcium channels was studied in solubilized synaptosomes from rat cerebellum. Antibodies against synaptotagmins I and II, but not IV co-immunoprecipitated [125I]omega-conotoxin MVIIC-labelled calcium channels. Direct interactions were studied between in vitro-translated [35S]synaptotagmin I and fusion proteins containing cytoplasmic loops of the alpha1A subunit (BI isoform). Gel overlay revealed the association of synaptotagmin I with a single region (residues 780-969) located in the intracellular loop connecting homologous domains II and III. Saturable calcium-independent binding occurred with equilibrium dissociation constants of 70 nM and 340 nM at 4 degrees C and pH 7.4, and association was blocked by addition of excess recombinant synaptotagmin I. Direct synaptotagmin binding to the pore-forming subunit of the P/Q-type channel may optimally locate the calcium-binding sites that initiate exocytosis within a zone of voltage-gated calcium entry.

Immunoassays fail to detect antibodies against neuronal calcium channels in amyotrophic lateral sclerosis serum

Recent studies suggested that autoantibodies that bind to voltage-dependent calcium channels and activate calcium entry may play a role in the progressive degeneration of motoneurons in sporadic amyotrophic lateral sclerosis. Immunoassays were performed to assess autoantibody titer in patients with amyotrophic lateral sclerosis or Lambert-Eaton myasthenic syndrome, a disease in which the presence of anti-calcium channel antibodies is well documented. Based on immunoprecipitation assays for antibodies against N-type calcium channels, only 8% (2/25) of amyotrophic lateral sclerosis patients had marginally positive titers, whereas 58% (18/31) of patients with Lambert-Eaton myasthenic syndrome had positive titers. Enzyme-linked immunosorbent assays with purified neuronal N-type calcium channels revealed immunoreactivity in 2 of 25 amyotrophic lateral sclerosis sera and 12 of 31 Lambert-Eaton myasthenic syndrome sera, which is not compatible with suggestions that enzyme-linked immunosorbent assay is a more sensitive technique for the detection of autoantibodies in amyotrophic lateral sclerosis. Furthermore, based on immunoprecipitation assays, amyotrophic lateral sclerosis sera were totally negative for antibodies against L-type calcium channels from skeletal muscle or brain. These data do not support the hypothesis that an autoimmune response against calcium channels plays a primary role in amyotrophic lateral sclerosis.

Sequential continuity of care by general practitioners: which patients change doctor?

OBJECTIVE

To identify individual and social characteristics of patients making sequential visits to a different rather than the same general practitioner (GP).

METHOD

Data for this study were extracted from the "Record Linkage Pilot Study" of the National Centre for Epidemiology and Population Health, which linked information from personal interviews with Health Insurance Commission and National Heart Foundation Risk Factor Survey data. Each sequence of visits (any two consecutive visits) made by each participant to the same or a different GP from January 1991 to December 1992 was treated as an event.

PARTICIPANTS

521 subjects aged between 23 and 72 years who gave consent to release of Health Insurance Commission data.

MAIN OUTCOME MEASURE

A visit to the same GP or a different GP from the one seen at the last visit.

RESULTS

Logistic regression analysis showed that younger age, good physical functioning, good self-rated health, normal body mass index, shiftwork and a longer time interval between visits were significantly associated with less continuity of care.

CONCLUSIONS

Our study raises questions about the relationship between chronological continuity and quality of care. For example, if infrequent visits (associated with less continuity) are for distinct illnesses, is quality of care affected by information or treatment from a previous visit? Our results also suggest that some GPs, because of the demography of their practices (more young people, a higher proportion of shift workers), may be disadvantaged by continuity-based reward systems. Moreover, because of lack of continuity young people may miss out on GPs' health promotional activities.

Recombinant ob protein reduces feeding and body weight in the ob/ob mouse

To determine whether the product of the recently cloned ob gene functions as an adipose-related satiety factor, recombinant murine ob protein was administered intraperitoneally to ob/ob mice. Monomeric ob protein given as single morning injections to groups of three animals at seven doses ranging from 5 to 100 micrograms reduced 24-h chow consumption in a dose-dependent manner from values of 81 +/- 6.8% of control (10-micrograms dose, P = 0.04) to 29 +/- 7.7% of control (100-micrograms dose, P < 0.0001). Daily injections of 80 micrograms of ob protein into six ob/ob mice for 2 wk led to an 11 +/- 1.6% decrease in body weight (P = 0.0009) and suppressed feeding to 26 +/- 4.9% of baseline (P < 0.0001), with significant reduction of serum insulin and glucose levels. The effect of recombinant ob protein on feeding was not augmented by cofactors secreted by adipose tissue, nor did exposure of adipose tissue to ob protein affect intracellular ob mRNA levels. Posttranslational modification of ob protein was not required for activity; however, addition of a hexahistidine tag to the amino terminus of the mature ob protein resulted in prolonged suppression of feeding after injection into ob/ob mice. These results demonstrate a direct effect of the ob protein to suppress feeding in the ob/ob mouse and suggest that this molecule plays a critical role in regulating total body fat content.

Development of esophageal epithelium in the fetal and neonatal mouse

Development of the fetal mouse esophageal epithelium was followed using light microscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and radioautography. At 15 days of gestation in the cervical (C), mediastinal (M), and abdominal (A) segments of the esophagus, the epithelium was two or three cells thick, and only cells located in the basal (germinal) layer incorporated tritiated thymidine. Ciliated cells were sparse in all three segments. At 17 days of gestation, longitudinal mesenchymal ridges became more differentiated in the distal segment. Labeling indices were lower than at preceding stages in each segment. Ciliated cells had increased in number and appeared to be evenly distributed along the whole esophagus. In periodic acid-Schiff (PAS)-stained sections, an increasing proximodistal distribution of glycogen stores was observed, with greatest concentrations found in segment A. At 18 days of gestation, labeling indices were comparable in segments C and M (11.7% +/- 2.9% and 12.8% +/- 1.9%, respectively) but remained higher in segment A (17.9% +/- 2.0%). Ciliated cells were still present. At this stage, transverse circular furrows and ridges started to appear. They increased in number at 4 days after birth and were very closely distributed in the adult. In longitudinal sections, these ridges corresponded to projections of stratum granulosum and of the overlying stratum corneum. After birth, ciliated cells desquamated rapidly but some patches were still present at 4 days. At 8 days, the esophageal epithelium was not yet keratinized.