Polymyxin B: similarities to and differences from colistin (polymyxin E)

Hospital-acquired infections due to multidrug-resistant Gram-negative bacteria constitute major health problems, since the medical community is continuously running out of available effective antibiotics and no new agents are in the pipeline. Polymyxins, a group of antibacterials that were discovered during the late 1940s, represent some of the last treatment options for these infections. Only two polymyxins are available commercially, polymyxin E (colistin) and polymyxin B. Although several reviews have been published recently regarding colistin, no review has focused on the similarities and differences between polymyxin B and colistin. These two medications have many similarities with respect to mechanism of action, antimicrobial spectrum, clinical uses and toxicity. However, they also differ in several aspects, including chemical structure, formulation, potency, dosage and pharmacokinetic properties.     

Polymyxin B: similarities to and differences from colistin (polymyxin E)

Hospital-acquired infections due to multidrug-resistant gram-negative bacteria constitute major health problems, since the medical community is continuously running out of available effective antibiotics and no new agents are in the pipeline. Polymyxins, a group of antibacterials that were discovered during the late 1940s, represent some of the last treatment options for these infections. Only two polymyxins are available commercially, polymyxin E (colistin) and polymyxin B. Although several reviews have been published recently regarding colistin, no review has focused on the similarities and differences between polymyxin B and colistin. These two medications have many similarities with respect to mechanism of action, antimicrobial spectrum, clinical uses and toxicity. However, they also differ in several aspects, including chemical structure, formulation, potency, dosage and pharmacokinetic properties.     

Primary care: differences and similarities

A group of health professionals from the United Kingdom visited New Zealand earlier this year. A nurse in the group shares her impressions.     

Audit and research: similarities and differences

Audit is an important aspect of quality assurance in health care, but misconceptions concerning its purpose, use and the limitations of its findings compared to research still exist. This article identifies the key features of audit and research, and discusses the defining features of both activities and their relationship.     

The proton-pump inhibitors: similarities and differences

OBJECTIVE: This paper examines the clinical pharmacology of the proton-pump inhibitors (PPIs) and briefly reviews some comparative studies of these agents. BACKGROUND: PPIs have emerged as the treatment of choice for acid-related diseases, including gastroesophageal reflux disease (GERD) and peptic ulcer disease. Although these drugs-omeprazole, lansoprazole, pantoprazole, and rabeprazole-share a common structure (all are substituted benzimidazoles) and mode of action (inhibition of H+,K+-adenosine triphosphatase [ATPase]), each differs somewhat in its clinical pharmacology. RESULTS: In comparative clinical trials found in MEDLINE, PPIs administered once daily produced endoscopic evidence of healing in >90% of patients with duodenal ulcer after 4 weeks of treatment, in >90% of those with gastric ulcer after 6 weeks of treatment, and in >90% of those with ulcerative or erosive GERD after 8 weeks of treatment. Maintenance therapy with daily doses of a PPI has been shown to be an effective means of preventing GERD relapse. PPIs also inhibit the growth of Helicobacter pylori, now recognized as an important factor in peptic ulcer disease, and, when administered in combination with antibiotics, provide the best treatment for eradication of the bacterium. Rabeprazole has a more rapid onset of H+,K+-ATPase inhibition than the other PPIs and, compared with omeprazole, a greater effect on intragastric pH after the first dose. Omeprazole and lansoprazole have a greater potential for drug-drug interactions than do pantoprazole and rabeprazole. CONCLUSION: Although the individual PPIs have similar efficacy in many cases, differences between them should be considered when choosing a treatment regimen.     

Cluster headache and SUNCT: similarities and differences

SUNCT is probably a distinct syndrome, although it shares some common features with cluster headache (CH): male sex preponderance, clustering of attacks, unilaterality of headache without sideshift, pain of non-pulsating type with its maximum in the periocular area, ipsilateral autonomic phenomena (e.g. conjunctival injection, lacrimation, rhinorrhea, increased forehead sweating), systemic blood pressure increment with heart rate decrement, blood flow velocity decrement in the middle cerebral artery, and hyperventilation. In spite of these similarities, SUNCT syndrome differs clearly from CH as regards a number of clinical variables, such as duration, intensity, frequency, and nocturnal preponderance of attacks. The two syndromes also differ markedly as regards precipitation of attacks, the usual age at onset, and efficacy of various treatment alternatives. Laboratory investigations have disclosed differences as regards presence or absence of Horner-like picture and possibily also the respiratory sinus arrhythmia pattern. All in all, these differences seem sufficiently ponderous to make it likely that SUNCT syndrome and CH differ essentially. SUNCT seems to be a “neuralgiform” headache, but different from trigeminal neuralgia. Received: 2 April 2001 / Accepted: 23 July 2001     

Is there HOPE for ALLHAT: similarities and differences

‵...percutaneous valve replacement may become an effective and versatile procedure, which could benefit a small patient population.′

     

Systemic lupus erythematosus and infectious endocarditis: similarities and differences

AIM: To compare clinical laboratory data in systemic lupus erythematosus (SLE) and infectious endocarditis (IE) for analysis of similar and different features. MATERIAL AND METHODS: Clinical and laboratory findings were compared for 72 IE and 71 SLE patients examined for a decade. RESULTS: SLE and IE have the following common features: fever, pleurisy, pericarditis, hemorrhagic vasculitis, articular syndrome, renal disorders, anemia, rheumatoid factor (RF), cryoproteins (CP), elevated ESR, concentrations of circulating immune complexes (CIC), IgM. Characteristic of SLE were skin erythema, alopecia, Raynaud's syndrome, cerebrovasculitis, lymphadenopathy, pneumonitis, frequent articular lesions, leucopenia, high IgG levels, CP and antibodies to DNA. IE was characterized by thromboembolic complications, splenomegaly, pneumonia, high CIC and medium mass molecules concentration, high incidence rate of RF, positive hemoculture. CONCLUSION: In spite of known differences between IE and SLE, in some cases differential diagnosis is not easy to make. This leads to late etiopathogenetic therapy.     

Provoked versus spontaneous migraine attacks: pathophysiological similarities and differences

BackgroundThe onset and duration of spontaneous migraine attacks are most often difficult to predict which, in turn, makes it challenging to study the neurobiologic underpinnings of the disease in a controlled experimental setting. To address this challenge, human provocation studies can be used to identify signaling molecules (e.g. calcitonin gene-related peptide, pituitary adenylate cyclase-activating polypeptide) that, upon intravenous or oral administration, induce migraine attacks in people with migraine and mild or no headache in healthy volunteers. This approach has proven to be valid for decades and plays an integral role in mapping signaling pathways underlying migraine pathogenesis and identification of novel drug targets. However, the question arises as to whether the pathogenic mechanisms of provoked and spontaneous migraine attacks differ. In this paper, we provide an opinionated discussion on the similarities and differences between provoked and spontaneous attacks based on the current understanding of migraine pathogenesis.MethodsThe PubMed database was searched in July 2022 for original research articles on human provocation studies that included participants with migraine. The reference lists of originally identified articles were also searched and we selected those we judged relevant.DiscussionPeople with migraine describe that provoked attacks resemble their spontaneous attacks and can be treated with their usual rescue medication. From a neurobiologic standpoint, provoked and spontaneous migraine attacks appear to be similar, except for the source of migraine-inducing substances (exogenous vs. endogenous source). In addition, provoked attacks can likely not be used to study the events that precede the release of migraine-inducing signaling molecules from sensory afferents and/or parasympathetic efferents during spontaneous attacks.     

IVUS-based imaging modalities for tissue characterization: similarities and differences

Gray-scale intravascular ultrasound (IVUS) is the modality that has been established as the golden standard for in vivo imaging of the vessel wall of the coronary arteries. The use of IVUS in clinical practice is an important diagnostic tool used for quantitative assessment of coronary artery disease. This has made IVUS the de-facto invasive imaging method to evaluate new interventional therapies such as new stent designs and for atherosclerosis progression-regression studies. However, the gray-scale representation of the coronary vessel wall and plaque morphology in combination with the limited resolution of the current IVUS catheters makes it difficult, if not impossible, to identify qualitatively (e.g. visually) the plaque morphology similar as that of histopathology, the golden standard to characterize and quantify coronary plaque tissue components. Meanwhile, this limitation has been partially overcome by new innovative IVUS-based post-processing methods such as: virtual histology IVUS (VH-IVUS, Volcano Therapeutics, Rancho Cordova, CA, USA), iMAP-IVUS (Bostoc Scientific, Santa Clara, CA, USA), Integrated Backscatter IVUS (IB-IVUS) and Automated Differential Echogenicity (ADE).     

Ethnic similarities and differences in early elementary teachers' responses to tobacco prevention

To explore ethnic differences in teachers' responses to tobacco prevention, 604 teachers, 26.6% of whom were African American (AA), attended an initial workshop, and 502 completed a four-week follow-up. Class sizes were equivalent, but AA teachers reported teaching relatively more AA students and fewer White students. On initial and follow-up questionnaires, AA teachers less often reported that their school had a tobacco-free policy. At follow-up, both groups reported using tobacco prevention materials and thought that they helped students. Despite less organizational support, AA teachers were as positive as White teachers about tobacco prevention for their K-3 students.     

Acute ischemic coronary artery disease and ischemic stroke: similarities and differences

Although acute myocardial infarction (MI) and acute ischemic stroke share similarities, physicians need to recognize important differences in pathophysiology and how these differences affect acute treatment and prevention to provide optimal patient care. Potential causes of acute ischemic stroke are substantially more heterogeneous than for acute MI, and available acute therapies are substantially more limited. In acute ischemic stroke patients, diagnostic evaluation is paramount in determining eligibility for treatment with the only approved therapy, which must be administered within 3 hours after stroke onset. For patients having acute MI, reperfusion therapy by percutaneous intervention or thrombolytic drug therapy is well established. Because atherosclerosis is a common pathway to acute MI and acute ischemic stroke, modifying associated known risk factors is required for primary and secondary prevention of both conditions. Pharmacologic therapies recommended for secondary prevention include beta-blockers and angiotensin-converting enzyme inhibitors for MI, oral anticoagulants for stroke, and statins and antiplatelet agents for both conditions. Aspirin is recommended for preventing recurrence of both MI and stroke; agents inhibiting the adenosine diphosphate pathway of platelet activation, such as ticlopidine and clopidogrel, are also beneficial. Recent studies suggest the benefits associated with adding aspirin to clopidogrel do not outweigh the significant increase in bleeding risk. The synergistic effects of aspirin plus extended-release dipyridamole make this combination twice as effective than aspirin alone in secondary prevention of ischemic stroke. An ongoing study is directly comparing the combination of aspirin plus extended-release dipyridamole with clopidogrel for the prevention of recurrent stroke.     

EverCare nurse practitioner practice activities: similarities and differences across five sites

PURPOSE: To examine the similarities and differences in the performance and frequency of performance of EverCare nurse practitioner (NP) practice activities at demonstration sites in five states. This study builds upon a previous study in which the development and testing of the EverCare Nurse Practitioner Role and Activity Scale (ENPRAS) was conducted. DATA SOURCES: A Background Data Sheet and the ENPRAS, a 99-item tool that encompasses six role subscales-Collaborator, Clinician, Care Manager/Coordinator, Counselor, Communicator/Cheerleader, and Coach/Educator, were completed by 127 EverCare NPs at demonstration sites in five states (Georgia, Maryland, Massachusetts, Colorado, and Florida). CONCLUSIONS: Performance of NP activities across the demonstration sites in five states was generally consistent, with significant differences only in the amount of time spent on activities associated with the Collaborator and Coach/Educator roles. Overall, EverCare NPs spent more time on Clinician and Communicator/Cheerleader role activities than on activities associated with the other roles. EverCare NP patient caseload was positively related to frequency of performance of the Clinician and Care Manager/Coordinator roles. IMPLICATIONS FOR PRACTICE: EverCare NPs provide proactive primary care to long-stay nursing home residents. The observed consistency reflects a strong centrally directed practice model. The identified roles and activities of the EverCare NP are consistent with previous studies and reports focused on the roles and activities of NPs who provide care to nursing home residents in other models of care delivery. Policy makers, healthcare providers, and the public should take these findings into account when considering a national model of care for this population. Future studies should examine the effect of variations in performance of activities on resident-specific and setting-specific outcomes.     

Doctoral programs in nursing: an examination of curriculum similarities and differences

In this exploratory study, eight doctoral programs in nursing (four PhD and four DNS/DSN/DNSc) were surveyed to examine curricular similarities and differences between research-oriented and professional-oriented programs. Content analysis was utilized to examine manifest content of 101 units of analysis derived from questionnaire items. These items reflected environmental input, curricular design, and outcome variables. Findings suggested that more curricular similarities than differences existed between the two program types. Curricular design variables reflected the most differences in the areas of program purposes and objectives. Several areas were identified for additional research in each variable category.     

Biological activity of a novel nonpeptide antagonist to the interleukin-6 receptor 20S,21-epoxy-resibufogenin-3-formate

Interleukin (IL)-6 is a key mediator in the regulation and coordination of the immune response and participates in pathogenesis of cancer cachexia, autoimmune disease, and postmenopausal osteoporosis. In the course of a screening program aimed at IL-6 inhibitor from natural products, we isolated 20S,21-epoxy-resibufogenin-3-formate (ERBF) from bufadienolide and examined the effect of ERBF on activities of various cytokines. ERBF dose dependently suppressed IL-6 activity and caused a parallel rightward shift of dose-response curves to IL-6 at concentrations of 0.03 to 10 ng/ml. Analysis of data yields a pA(2) of 5.12 and a slope of 0.99. Selectivity of ERBF on activity of cytokines was examined using cytokine-dependent cell lines. ERBF did not affect IL-2-dependent growth of CTLL-2 cells, IL-3-dependent growth of Baf3 cells, or tumor necrosis factor (TNF)alpha-induced growth suppression in TNFalpha-sensitive L929 cells. ERBF also did not affect IL-4-stimulated expression of FcepsilonR II receptor (CD23) in U-937 cells, the IL-8-induced chemotaxis of human neutrophils, or nerve growth factor-stimulated neuronal differentiation in PC-12 cells. In contrast, ERBF dose dependently suppressed IL-6-induced neuronal differentiation in PC-12 cells. Furthermore, ERBF suppressed only IL-6-induced osteoclast formation without affecting osteoclast formation induced by IL-11, leukemia inhibitory factor, and 1alpha,25-dihydroxyvitamin D(3). In receptor binding assay, unbound (free) IL-6 was increased in a dose-dependent manner by pretreatment with ERBF on IL-6 receptor (IL-6R), suggesting that ERBF suppresses binding of IL-6 to IL-6R. These results clearly indicate that ERBF is a novel specific small molecule to show IL-6 receptor antagonist activity.     

Sex similarities and differences in pain-related periaqueductal gray connectivity

This study investigated sex similarities and differences in pain-related functional connectivity in 60 healthy subjects. We used functional magnetic resonance imaging and psychophysiological interaction analysis to investigate how exposure to low vs high experimental pain modulates the functional connectivity of the periaqueductal gray (PAG). We found no sex differences in pain thresholds, and in both men and women, the PAG was more functionally connected with the somatosensory cortex, the supplemental motor area, cerebellum, and thalamus during high pain, consistent with anatomic predictions. Twenty-six men displayed a pain-induced increase in PAG functional connectivity with the amygdala caudate and putamen that was not observed in women. In an extensive literature search, we found that female animals have been largely overlooked when the connections between the PAG and the amygdala have been described, and that women are systematically understudied with regard to endogenous pain inhibition. Our results emphasize the importance of including both male and female subjects when studying basic mechanisms of pain processing, and point toward a possible sex difference in endogenous pain inhibition.