Proven Relationship Research Articles

OVERTIME WORK AS A SIGNALING DEVICE†

ABSTRACTThis paper provides an explanation for the empirically proven relationship between overtime and future benefits. We suggest an internal signaling model, in which a worker signals his value to the employer by supplying unpaid overtime. In our empirical analysis, we examine whether overtime has in fact a signaling component. Variations in collectively bargained hours between industries are exploited, as they imply different overtime thresholds for workers with the same number of actual hours. Using data from the German Socio‐Economic Panel Study for the years 1993–2004, a positive signaling value of unpaid overtime is found for West German workers.

Cannabis: the next villain on the lung cancer battlefield?

Lung cancer epidemics arose and spread in western countries when the tobacco industry created the manufactured cigarette and realised that nicotine addiction was the most adaptable way to increase and secure long-term sales 1. In spite of well-known toxicity of tobacco smoke 2 and the proven relationship of tobacco smoking with lung cancer incidence 3, the tobacco industry took advantage of the lack of response by western governments, concerning the alarms raised by physicians and citizen associations, and set up a very powerful marketing process directed at smokers, adult males and nonsmokers, females and adolescents with devastating effects. In all western countries the percentage of smokers increased, and the age at which the first cigarette was smoked decreased. Since susceptibility of females to tobacco carcinogens is higher, lung cancer in females equalled or exceeded lung cancer in males in different countries 4, even in females with a lower, but regular, cigarette consumption. The age of lung cancer occurrence followed the age that people started smoking. In the 1950s, the average ages for the first cigarette smoked and for lung cancer onset were 20–30 yrs and ≥60 yrs, respectively, but at the turn of the 20th century these were <12 yrs and ≥40 yrs, respectively. The electroshock was the revelation of the tobacco industry’s …

A strange property of the determinant of minors

If Mi j are minors of an n × n determinant D with elements aij (1 ≤ i, j ≤ n), then we prove the following relationship where Mk is any square sub matrix of order k of the matrix of minors M, δk is the determinant of a submatrix of D of order (n − k) taking the complements of the row/column positions that was used in Mk , and 1 ≤ k ≤ n. The above relation generalizes the trivial case for k = 1 and is consistent with the proven relationship for k = n when δn is taken as 1.

Support Vector Machine combined with K-Nearest Neighbors for Solar Flare Forecasting

A method combining the support vector machine (SVM) the K-Nearest Neighbors (KNN), labelled the SVM-KNN method, is used to construct a solar flare forecasting model. Based on a proven relationship between SVM and KNN, the SVM-KNN method improves the SVM algorithm of classification by taking advantage of the KNN algorithm according to the distribution of test samples in a feature space. In our flare forecast study, sunspots and 10 cm radio flux data observed during Solar Cycle 23 are taken as predictors, and whether an M class flare will occur for each active region within two days will be predicted. The SVM-KNN method is compared with the SVM and Neural networks-based method. The test results indicate that the rate of correct predictions from the SVM-KNN method is higher than that from the other two methods. This method shows promise as a practicable future forecasting model.

A Clinically Proven, Prospective, Thermal Dose Descriptor Exists

In Response: We appreciate the consideration that Dr. van der Zee and her group have given to our recent hyperthermia trial in canine sarcomas published in Clinical Cancer Research ([1][1]). It is apparent that they have scrutinized our trial very carefully and we welcome this examination. However,

Mechanisms of Disease: infection and spondyloarthritis

There is compelling evidence that some infections can initiate a chronic nonseptic arthritis. This has proved to be an important area of investigation into gene-environment interactions, particularly since HLA-B27 confers increased susceptibility to reactive arthritis. This research has investigated the microbiology of these events, and the strategies used by pathogens to induce chronic joint inflammation. Insights into the HLA-orchestrated immune response in this context have also shed light on the impact of HLA-B27 on immunity, which might provide insights into the mechanism of other HLA-B27-associated diseases. Despite the genetic link to reactive arthritis, there is no proven relationship between ankylosing spondylitis and an inciting infection. In general, most trials have found antibiotics to be ineffective in modifying the course of spondyloarthritis.

The influence of gender on skeletal muscle endurance capacity

Skeletal muscle function and its role in providing joint stability has been the focus of considerable interest over the last few years. A proven relationship between spinal pain and sub-optimal muscle function, including endurance capacity, affirms the importance of functional stability re-training in the management of patients with neuromusculoskeletal dysfunction. Clinical protocols, based upon the use of the same target forces, repetitions, and contraction times for both genders are currently used as a basis for evaluating changes in spinal muscle endurance capacity. However these protocols do not account for the gender-related differences in endurance capacity that have been shown to exist in some of the literature, where women have recorded higher values for endurance capacity compared with men. This paper reviews the literature that has sought to evaluate the influence of gender on endurance capacity, discusses the physiological mechanisms that may account for observed differences, and considers the possible clinical implications for physiotherapists.

Football U.: Spectator Sports in the Life of the American University (review)

Reviewed by: Football U.: Spectator Sports in the Life of the American University Edward St. John (bio) J. Douglas Toma. Football U.: Spectator Sports in the Life of the American University. Ann Arbor: University of Michigan Press, 2003. 292 pp. Cloth: $29.95. ISBN: 0-472-11299-6. Football U.: Spectator Sports in the Life of the American University takes a fresh look at the role of big-time college sports and, in the process, makes a compelling argument about the institution-building process. Douglas Toma appeals to inner images of college football that many of us hold, either from personal experience or television Saturdays, and challenges us to think about how these images relate to the culture of colleges, the commitments of alumni to their alma maters, and the ability of major universities to raise money. He builds a persuasive case that success on the sports field is central to the success of universities, but does the case hold up beyond schools with a history of victory? A good writer as well as a skilled lawyer, Toma tells an interesting story about college sports, creating vivid mental pictures of fall football weekends, [End Page 448] complete with tailgate parties. While many academics and policymakers criticize college sports for violence, corruption, and high costs, Toma argues that these flaws should not cause us to lose sight of the value of the big football weekend. He demonstrates how the legal skills of argumentation can build a defense that should be appealing to sports fans with an interest in academe. It is noteworthy how well Toma weaves insights from the literature on higher education into a book that could attract general readers. A scholar of higher education, he crafts chapters that draw upon John Thelin's colorful histories and sprinkles in compelling insights from the literatures on students, the commercialization of sports in higher education, public support for higher education, and alumni relations and development—areas well-represented in the scholarship in our field. Toma also ventures into the role of brands, symbols, and media—topics our field has not studied sufficiently. Toma builds the case for viewing sports as an integral part of academic life and the institution-building process in major universities. Since it was written like a defense statement, however, Toma's text does not always provide a balanced or critical treatment of college sports. A contrasting view can be found in Derek Bok's Universities in the Marketplace: The Commercialization of Higher Education (2003). Bok describes historical patterns of the commercialization of athletics, arguing that universities can overinvest in sports teams, creating financial problems. Bok draws a parallel between overinvestment in sports and excessive spending on the development of electronic degree programs. He notes also that enthusiastic commercialization in sports can have high costs for universities, leading to long-term financial problems. We find no such criticism or constraints on exuberance in Toma's treatment of commercialization: Institutions must then hope people remember [that] a university lies beyond the football stadium, and that commercialism associated with spectator sports does not erode the integrity that society expects of higher education. . . . Prestige may be more important than actuality of quality here—perceptions may matter more than an actual job being done. Given the connections between athletics success and institutional prestige, a weak football program can prove to be a distraction when seeking external support to advance key initiatives and agendas. Along the same lines, a strong program may encourage needed support. (p. 120) Thus, Toma skims over the downside of commercialization by extolling the virtues of winning. Having a winning team, he argues, brings in state funding, private gifts, and students from in state and out of state. He does not examine research literature to determine whether there is a proven statistical relationship between winning sports teams and enrollment. Rather he makes the assertion largely with anecdotes and interviews with officials in 11 football universities to build his case. But what about the experiences of the many institutions that have made substantial investments in sports and have not had teams with national titles? There is a great deal of financial risk associated with the goal of becoming a contender in...

Das Brustkrebs-Präventionsverhalten in der Schweiz: aus der Perspektive von Frauen aus drei Sprachregionen der Schweiz

Swiss women show, together with women from the Netherlands, France, Belgium, Sweden, Finland, England and Germany, a very high incidence of breast cancer in Europe. Whilst the evidence for primary cancer prevention is slowly growing, its strategies can not yet be implemented in clinical prevention programmes. Therefore, secondary prevention, early detection of cancer, remains the main focus for reducing breast cancer mortality. This is especially true because of the proven relationship between mortality and size of the primary tumour as well as the status of the axilla. Despite these facts, in contrast to the French part of Switzerland, breast cancer screening has not yet been implemented in the German and Italian part of Switzerland. It was the aim of this study to identify prevention measures used by women living in the German-, Italian- and French-speaking part of Switzerland and to explore their attitude towards breast cancer prevention measures. It was asked what these women knew about breast cancer prevention, what type of secondary prevention they used and who motivated them to do so. The investigation included 1721 women from three language regions of Switzerland. Data were collected with a postal survey questionnaire. Descriptive, uni- and multivariate methods were used for data analysis. The response rate was 34%. Statistically significant differences in breast self-examination were observed between the three regions (p = < 0.001) and defined age-groups (p = < or = 0.001). In all three regions of the country, 90% of women age 50-59 had mammograms, whereas in comparison to the other regions, fewer women from the German part of Switzerland, aged 60-69, had undergone mammography screening. Significant differences in mammography screening again were observed between language regions (p = < or = 0.001) and age-groups (p = < or = 0.001). Eighty-four percent of women were motivated by the gynaecologist to have a mammography, 11% by the family doctor and 10% of the women decided by themselves. More than half of this female Swiss study population wished to see a health policy providing mammography-screening in Switzerland and about one third wished to be more informed about the intervention. An increased need for information and education about prevention and early detection was observed in individuals who had a relative with cancer. The majority of women in this study wished to see a health policy in Switzerland which includes a mammography screening programme. Opportunistic mammography screening, lacking systematic quality control and data collection for epidemiological purposes, was widely used in the Italian and in the German speaking region. Data show that there is a need for public and professional information and education about prevention and early detection of breast cancer to prevent misconceptions regarding the effect of breast self-examination and mammography-screening. Womens' organisations and nurses may be in a good position to take up a leading role in breast cancer prevention.

Trunk muscular strength in pre-pubertal children with and without back pain.

While in adulthood there is no proven relationship between back pain and trunk muscle strength, in pre-pubertal subjects this topic has been poorly studied. The aim of the study was to evaluate isometric and isokinetic trunk muscle strength in children with or without previous back pain. The recent occurrence of back pain (last 6 months) among 144 children (77 males, 67 females, age 11.9 +/- 0.3 years) was assessed using a questionnaire. Extensor and flexor trunk muscle strength was measured through isometric and isokinetic (60, 90, 120 degrees/s) tests. Peak torque (PT), PT angle, PT flexor/PT extensor ratio and intra-session coefficient of variation (COV) were determined. Flexor and extensor muscle PT, but not PT angle, were significantly higher in males than in females, irrespective of back pain occurrence. PT flexor/PT extensor ratio at 90 degrees angular velocities increased significantly only in males with back pain, compared with males without back pain. The COV trend was similar for flexor and extensor muscles. Isometric and isokinetic trunk muscle strength probably play a minor role in back pain occurrence in children. The isokinetic testing velocity may be important in determining trunk strength differences between children with and without back pain.

Changes in viremia and circulating interferon-α during hemodialysis in hepatitis C virus-positive patients: only coincidental phenomena?

Background:It has been hypothesized that hemodialysis (HD) treatment per se can preserve patients from an aggressive course of hepatitis C virus (HCV) infection by reduction of viral load. The aim of the present study in HCV-positive (HCV+) HD patients is to determine whether HD induces the production of interferon-α (IFN-α) and if such production can contribute to viremia reduction. Methods:To address this issue, HCV RNA and IFN-α levels were determined in 11 HCV+ patients immediately before and at the end of a 4-hour dialysis session using cellulosic membranes and 24 and 48 hours later, ie, immediately before the subsequent dialysis session using the same membrane and at the end of the dialysis session. The same protocol was repeated 1 week later using a high-biocompatibility synthetic membrane. Results:HCV titer decreased in all patients after dialysis (range, 3% to 95%; P = 0.001) and thereafter progressively increased and returned to basal levels within 48 hours, with a new reduction during the next dialysis treatment. There was no significant difference in the magnitude of changes in HCV titers in tests performed using cellulosic or synthetic membranes. Plasma IFN-α levels increased markedly after dialysis using both cellulosic (in 9 of 11 cases) and synthetic membranes (in 10 of 11 cases; P < 0.01) and returned to basal levels within 48 hours; thereafter, IFN-α levels increased again during the next dialysis session. In some patients, plasma IFN-α levels after HD were approximately 50% of the level observed after therapeutic administration of 6 million units of IFN-α to 4 HD patients with chronic hepatitis. Conclusion:Although without a proven direct cause-effect relationship between HCV level reduction and induction of IFN-α after dialysis, our observation suggests an additional new mechanism for the unusually mild course of HCV infection in HD patients.

Health risk for children from lead and cadmium near a non-ferrous smelter in Bulgaria

In an interdisciplinary approach the exposure to lead and cadmium of the population living in the vicinity of a Bulgarian non-ferrous metallurgical plant was studied to determine the routes of exposure. Two exposed villages situated 4 and 6 km SW and W, respectively, – in the plume of the plant's emissions – and a village for comparison situated 14 km SE of the plant were selected for the study. The blood of children aged 3 – 13 years from the exposed villages (n=111) and the village for comparison (n=18) was analyzed for lead (PbB) and cadmium (CdB) as well as for free erythrocyte protoporphyrin (FEP) and haematological parameters. A personal questionnaire concerning nutrition habits and life-style was filled in by interviewers of the children's parents.The cadmium levels in blood were within the variation range stated for Bulgaria. The exposed children had a mean CdB of 0.38±0.18 μg/l (range 0.10 – 0.90 μg/l) and the comparison group 0.31±0.35 μg/l (0.06 – 1.42 μg/l). The mean PbB value measured in the exposed children was 240±96 μg/l (77 – 631 μg/l), while the mean value of PbB for the reference group was 149±57 μg/l (63 – 285 μg/l). Individual PbB levels >150 and >200 μg/l were found in 85% and 62%, respectively, of the exposed children and FEP >80 μg/dl erythrocytes was detected in 21%. There was a concentration-response and a concentration-effect relationship (r=0.51, D>0.001) between PbB and FEP.According to the questionnaire only 10.3% of the interviewed families in the two exposed villages buy all food from the market, the others produce a significant part of their food themselves. The PbB levels of children who consume certain foods of local production (cabbage, cereals, poultry, and beef) were significantly higher compared to the PbB values of children whose families purchase these foods from the market. No significant relationship between lead in children's blood and the use of tin and ceramic utensils, drinking and irrigation water, hygiene habits, family tobacco smoking habits, playgrounds and traffic intensity were revealed. There was a significantly higher incidence of prematurely born babies in the exposed population.The proven relationship between lead intake via the food chain and existing significant health risks is the basis for risk communication. Measures aimed at healthier nutrition and life-style intend to contribute to decreasing the risk of the population living in the smelter region.

Hyperhomocyst(e)inemia Induces Accelerated Transplant Vascular Sclerosis in Syngeneic and Allogeneic Rat Cardiac Transplants

Chronic rejection (CR) and transplant vascular sclerosis (TVS) cause the majority of graft failures in cardiac transplantation. Hyperhomocyst(e)inemia [hH(e)] is associated with human TVS without a proven causal relationship. This study investigated the effect of hH(e) on graft survival and TVS in allogeneic and syngeneic rat cardiac transplants. Lewis recipients of heterotopic F344 heart allografts, received normal or hH(e)-inducing (↓folate, ↑methionine) diets {controls: syngeneic transplanted [± hH(e), + CsA] and nontransplanted rats [± hH(e), ± CsA]}. Serial plasma homocyst(e)ine [H(e)] levels were measured. TVS was assessed in clinically rejected grafts and a subset of pre-rejection normal diet allografts (day 64) (neointimal index, NI). The hH(e) diet elevated plasma H(e) levels. When compared with normal diet controls (n = 9), hH(e) diet allografts (n = 9) had decreased time to onset of CR (40 ± 9 vs. 72 ± 10 d, p = 0.02), and graft failure (64 ± 10 vs. 107 ± 12 d, p = 0.009). hH(e) diet allografts at rejection (n = 9, 64 d) had more severe TVS (NI = 68 ± 2) than both time-matched normal diet allografts (NI = 49 ± 6, n = 8, 64 d, p < 0.001) and normal diet allografts at rejection (NI = 58 ± 5, n = 9, 107 d, p = 0.007). hH(e) induced TVS in syngeneic grafts (NI = 50 ± 3, n = 10 vs. NI = 5 ± 3, n = 10, 130 d, p < 0.001). hH(e) accelerated rejection and increased the severity of TVS in allogeneic cardiac transplants, and induced TVS in syngeneic cardiac transplants.

Oncological complications of excess GH in acromegaly.

Around fifteen percent of the deaths reported in acromegaly are attributable to malignancy (SM Melmed, J Clin Endocrinol Metab 2001;86:2929-2934; A Mestrón, SM Webb, In: Endocrine Society, San Francisco, June 2002 (abstract)), uncontrolled disease is associated with a growth advantage for concurrent neoplasms, which are more likely to be aggressive; however, there is no clear evidence of de novo cancer initiation in acromegaly and no proven causal relationship of acromegaly with malignant disease. Overall and cancer mortality in acromegaly have been shown to correlate with the degree of GH control; if post therapy GH is controlled, both the overall and cancer mortality do not appear to differ from that of the normal population (SM Orme et al., J Clin Endocrinol Metab 1998;83:2730-2734; JD Nabarro, Clin Endocrinol 1987;26:481-512). However, no long-term prospective evaluation of cancer prevalence or its relation to biochemical or clinical disease activity is available. IGF-1 appears to exert a permissive effect on tumorigenesis; there is no clear evidence that tumor initiation is triggered by IGF-1 in acromegaly; nevertheless, since IGF-1 may be higher in neoplasms, aggressive treatment aimed at controlling the disease activity will theoretically be advantageous for acromegalic patients with cancer. The prevalence of colon polyps and colon cancer appear to be incresed in acromegaly as is mortality for colon cancer (Orme et al., 1998), so regular colonoscopy screening and polypectomy would seem advisable, especially in older patients with active acromegaly. Surveillance for prostate cancer in elderly males with high IGF-1, especially if also receiving testosterone replacement therapy, is recommendable, by measurement of serum PSA, rectal examination and/or prostatic ultrasound. In women, mammography should be offered, especially after the age of 50 years, as in the normal population. Neither prostate nor breast cancer have been consistently shown to have an increased prevalence in acromegaly, but larger prospective epidemiological studies are required to study this further.

Chronic splanchnic ischaemia

Chronic splanchnic ischaemia is a relatively unusual clinical entity consisting of pain and/or weight loss and caused by chronic splanchnic disease (i.e. stenosis and/or occlusion of the coeliac and superior mesenteric artery). The occlusive disease is usually caused by atherosclerosis and is in itself not rare in older individuals. Extensive collateral circulation can develop between the three splanchnic arteries and may compensate for the decreased splanchnic perfusion over time. The pathophysiology of chronic splanchnic ischaemia has still not been completely elucidated.A reliable diagnosis of chronic splanchnic ischaemia, based on a proven causal relationship between the occlusive disease and the symptoms, can be very difficult. Traditionally, tests for evaluating the haemodynamic consequences of the vascular stenoses were not available. Important improvements in establishing a more reliable diagnosis have been achieved with duplex ultrasound and magnetic resonance evaluation of the splanchnic circulation. Tonometry is another promising functional test that may prove useful not only for gaining greater insight into the pathophysiology of chronic splanchnic ischaemia but also for the clinical evaluation of this syndrome.The natural history of chronic splanchnic disease suggests that progressive disease may result in acute mesenteric ischaemia. Surgical reconstruction of the coeliac and/or the superior mesenteric artery is the therapeutic standard with excellent short and long-term results. Satisfactory early results using angioplasty with or without stent suggest that this type of intervention may relieve symptoms in selected patients with a higher surgical risk.

Nucleoside exposure in the children of HIV-infected women receiving antiretroviral drugs: absence of clear evidence for mitochondrial disease in children who died before 5 years of age in five United States cohorts.

Nucleoside reverse transcriptase inhibitors (NRTIs) have been associated with mitochondrial toxicity in individuals receiving treatment. A report of two deaths in Europe attributed to mitochondrial dysfunction in HIV-uninfected infants with perinatal NRTI exposure prompted a review of five U.S. cohorts. Deaths in HIV-exposed children <60 months of age and HIV-uninfected or indeterminate were reviewed. Review included birth history; perinatal antiretroviral drug exposure; hospital, laboratory, and clinic records; death reports; autopsy results; and local physician queries. Deaths were classified as unrelated (Class 1), unlikely related (Class 2), possibly related (Class 3), or highly suggestive or proven relationship (Class 4), to mitochondrial dysfunction; sudden infant death syndrome (SIDS) was categorized separately. Among over 20,000 children of HIV-infected women, over half of whom had been exposed to NRTIs, 223 died. In HIV-uninfected children, 26 deaths were attributed to Class 1, and 4 were attributed to SIDS. In HIV-indeterminate children, 141, 10, 3, and 0 were Classes 1, 2, 3, and 4, respectively; 33 were due to SIDS and 6 could not be classified. There was no indication that antiretroviral exposure was associated with Class 2 or 3 deaths, or deaths from SIDS. A search for mitochondrial dysfunction among living children in these cohorts is ongoing.

Heritability of gastrointestinal nematode faecal egg counts in West African village N’Dama cattle and its relation to age

Offspring–dam regression was used to estimate the heritability of strongyle faecal egg counts (FEC) of traditionally raised West African N’Dama cattle in the Central River Division in The Gambia. Faecal samples were taken monthly from June–October 1992, and again from July–October 1993, including 179–463 dams and their calves sampled on each occasion. The only proven genetic relationship was the dam–offspring relationship. Gastrointestinal strongyle FEC was expressed as epg (eggs per gram faeces). Regression of offspring FEC on dam FEC, showed a heritability ( h 2) of 0.18 (95% Confidence Limits 0.10, 0.25). Heritabilities were higher at the beginning and end of the rainy season than during the months of the peak rainy season. This is in line with earlier suggestions that genetic control of faecal egg counts is most effective during periods of low parasite transmission. There was a significant ( p<0.001) increase in heritability of 0.086±0.018 with each year of age of the corresponding offspring. In view of the virtual absence of national cattle breeding systems in West Africa, which are a precondition for exploitation of heritable traits in cattle, integrated control using improved management and strategic prophylaxis remain the methods of choice to control gastrointestinal nematodes in the given conditions.

Expanding clinical applications of population pharmacodynamic modelling.

Population pharmacokinetics or pharmacodynamics is the study of the variability in drug concentration or pharmacological effect between individuals when standard dosage regimens are administered. We provide an overview of pharmacokinetic models, pharmacodynamic models, population models and residual error models. We outline how population modelling approaches seek to explain interpatient variability with covariate analysis, and, in some approaches, to characterize the unexplained interindividual variability. The interpretation of the results of population modelling approaches is facilitated by shifting the emphasis from the perspective of the modeller to the perspective of the clinician. Both the explained and unexplained interpatient variability should be presented in terms of their impact on the dose-response relationship. Clinically relevant questions relating to the explained and unexplained variability in the population can be posed to the model, and confidence intervals can be obtained for the fraction of the population that is estimated to fall within a specific therapeutic range given a certain dosing regimen. Such forecasting can be used to develop optimal initial dosing guidelines. The development of population models (with random effects) permits the application of Bayes's formula to obtain improved estimates of an individual's pharmacokinetic and pharmacodynamic parameters in the light of observed responses. An important challenge to clinical pharmacology is to identify the drugs that might benefit from such adaptive-control-with-feedback dosing strategies. Drugs used for life threatening diseases with a proven pharmacokinetic-pharmacodynamic relationship, a small therapeutic range, large interindividual variability, small interoccasion variability and severe adverse effects are likely to be good candidates. Rapidly evolving changes in health care economics and consumer expectations make it unlikely that traditional drug development approaches will succeed in the future. A shift away from the narrow focus on rejecting the null hypothesis towards a broader focus on seeking to understand the factors that influence the dose-response relationship--together with the development of the next generation of software based on population models--should permit a more efficient and rational drug development programme.

Sinus node recovery time assessment revisited: role of pharmacologic blockade of the autonomic nervous system.

Sinus node recovery time assessment is used to diagnose clinically significant sinus node dysfunction (SND) when Holter has failed to prove a relationship between sinus bradyarrhythmias and symptoms, but consensus has not been reached as to the value of including assessment after pharmacologic blockade of the autonomic nervous system. This issue was addressed in the present study performed on 52 patients with syncope or presyncope/dizziness (n = 48), sinus bradyarrhythmias (n = 45), or both (n = 41). Group 1 consisted of 13 patients with a proven relationship between symptoms and sinus bradyarrhythmias. Group 2 consisted of 39 patients with suspected SND. The protocol included three pacing periods at two pacing rates and was performed at baseline (n = 52), after single doses of atropine and propranolol (0.02 mg/kg and 0.1 mg/kg, respectively) (n = 41), and again after a second dose (n = 29). The sensitivity of prolonged recovery times was 77% in group 1. Among group 2 patients, 56% had prolonged recovery times at baseline (79% when including the results after the first dose of drugs). The second dose did not contribute diagnostic information, but it caused significant adverse reactions in 7 of 29 patients (P < 0.001). These 7 patients were all older than 60 years. Assessment of sinus node recovery time after pharmacologic blockade of the autonomic nervous system thus increases the sensitivity of the method in patients with suspected SND and normal baseline results. However, only 50% of the initially suggested doses of atropine and propranolol is sufficient and eliminates the risk for significant adverse reactions.

Current status of Helicobacter pylori in peptic ulcer disease.

All patients with documented, past or present gastric or duodenal ulcers and who are infected with Helicobacter pylori should undergo antimicrobial therapy to eradicate it. Data do not yet support giving antimicrobial therapy to treat nonulcer dyspepsia or to prevent gastric neoplasia. H pylori infection is the main cause of chronic superficial gastritis and is associated with both gastric and duodenal ulcers. However, it has no proven relationship with nonulcer dyspepsia. H pylori infection is currently diagnosed by either endoscopic biopsy or serologic titers for a specific immunoglobulin (IgG) antibody. No noninvasive technique is available to document eradication of infection, although urea breath tests will soon simplify both the diagnosis of infection and documentation of eradication. Eradicating H pylori infection decreases the rate of ulcer recurrence. Treatment currently involves a 2-week, three-drug regimen of bismuth subsalicylate, tetracycline, and metronidazole, or a two-drug regimen of omeprazole and amoxicillin; other, simpler regimens are under investigation.