Calcium pyrophosphate deposition disease: historical overview and potential gaps

CPPD disease can affect patients’ quality of life through its various clinical presentations. This mini-review discusses the evolution of CPPD from its discovery to current knowledge of its pathogenesis, genetic associations, diagnostics, and treatment options. Despite extensive research, the exact mechanisms of CPPD are not well understood, and there is a notable lack of knowledge about psychosocial impacts and patient experiences. This study aims to present a CPPD Disease Timeline identifying gaps in current knowledge and potential directions for future research. These findings contribute to a broader understanding of CPPD disease and emphasize the importance of continued research and innovation in this field.

Central and peripheral mechanisms of pain in fibromyalgia: scoping review protocol

Fibromyalgia is characterised by widespread musculoskeletal pain, which may present with fatigue, depression, anxiety, sleep and cognitive disturbances. It is the second most prevalent rheumatic disease. An accurate diagnosis is challenging, since its symptoms may resemble diverse conditions such as carpal tunnel syndrome, Raynaud syndrome, Sjögren syndrome, amongst others. Neuropathic pain and autonomic dysfunction in fibromyalgia suggest the involvement of the nervous system. Ion channels, neurotransmitters and neuromodulators may play a role. Small fibre neuropathy (SFN) may also cause chronic widespread pain. SFN may occur in 50% of fibromyalgia patients, but its role in the disease is unknown. Despite several efforts to synthesise the evidence on the mechanisms for pain in fibromyalgia, there are few studies applying an integrative perspective of neurochemical, immunological, and neuroanatomical characteristics, and their relevance to the disease. This protocol aims to clarify the mechanisms of the central and peripheral nervous system associated with pain in fibromyalgia. We will retrieve published studies from Web of Science, MEDLINE, Scopus, EBSCOhost, Ovid and Google Scholar. All clinical studies or experimental models of fibromyalgia reporting imaging, neurophysiological, anatomical, structural, neurochemical, or immunological characteristics of the central or peripheral nervous systems associated with pain will be included. Exclusion criteria will eliminate studies evaluating pain without a standardised measure, studies written in languages different from Spanish or English that could not be appropriately translated, and studies whose full-text files could not be retrieved after all efforts made. A narrative synthesis will be performed.

Update of the current role of ultrasound in asymptomatic hyperuricemia. A systematic literature review

Ultrasound (US) is a recognized imaging modality for the assessment of gout. Recently it is being explored for its potential role in the evaluation of subjects with asymptomatic hyperuricemia (AH). Preliminary reports demonstrated the presence of monosodium urate (MSU)-crystal deposits including aggregates, double contour sign and/or tophi in both intra-articular and periarticular tissues of AH individuals. Although these results are exciting, the value and potential application of US in AH remain to be clearly delineated. In this systematic literature review, we aim to summarise the recent publications regarding the role of US in the assessment of AH. We analyzed possible application of US in the daily clinical practice and its future clinical and research potential in the evaluation of AH individuals.

Quantifying Potential Cost-Savings Through an Alternative Imaging-Based Diagnostic Process in Presumptive Seronegative Rheumatoid Arthritis

Background

Seronegative rheumatoid arthritis (SRA) is a condition that is not well understood and difficult to confirm by a conventional diagnostic process. We aimed to quantify the potential cost-savings of an alternative diagnostic process (ADP) imaging-based, for patients with presumptive SRA from everyday clinical practice.

Methods

We performed a retrospective analysis for patients with presumptive SRA who tested negative for both rheumatoid factor and anti-cyclic citrullinated peptide antibodies, through an ADP imaging-based, that is a standard clinical practice in our center. After we confirmed the diagnosis of SRA or reclassified patients in terms of another proper diagnosis, we estimate direct costs in two scenarios: a conventional and ADP. We compared the cost of RA treatment during the first year against the cost of the most misdiagnosed treatment (osteoarthritis) found after applying the ADP to determine potential cost-savings.

Results

We included 440 patients with a presumptive diagnosis of SRA. According to the imaging-based ADP, SRA was confirmed in 106/440 (24.1%), unspecified RA in 9/440 (2.0%), and osteoarthritis in 325/440 (73.9%) of those patients. Although the costs of conventional diagnosis per patient is lower than those of ADP ($59,20 USD vs $269,57 USD), we found a potential drug cost-savings of $1,570,775.20 US Dollars after 1 year of correct treatment.

Conclusion

An alternative diagnosis process, including X-rays, US and MRI imaging, and clinical and blood-test assessment, not only increased diagnostic certainty in patients referred for evaluation of presumptive SRA but also suggested a potential cost-savings in pharmacological treatments avoided in misdiagnosed patients.

Therapeutic Potential of Ultrasound Neuromodulation in Decreasing Neuropathic Pain: Clinical and Experimental Evidence

Background

For more than seven decades, ultrasound has been used as an imaging and diagnostic tool. Today, new technologies, such as focused ultrasound (FUS) neuromodulation, have revealed some innovative, potential applications. However, those applications have been barely studied to deal with neuropathic pain (NP), a cluster of chronic pain syndromes with a restricted response to conventional pharmaceuticals.

Objective

To analyze the therapeutic potential of low-intensity (LIFUS) and high-intensity (HIFUS) FUS for managing NP.

Methods

We performed a narrative review, including clinical and experimental ultrasound neuromodulation studies published in three main database repositories.

Discussion

Evidence shows that FUS may influence several mechanisms relevant for neuropathic pain management such as modulation of ion channels, glutamatergic neurotransmission, cerebral blood flow, inflammation and neurotoxicity, neuronal morphology and survival, nerve regeneration, and remyelination. Some experimental models have shown that LIFUS may reduce allodynia after peripheral nerve damage. At the same time, a few clinical studies support its beneficial effect on reducing pain in nerve compression syndromes. In turn, Thalamic HIFUS ablation can reduce NP from several etiologies with minor side-effects, but some neurological sequelae might be permanent. HIFUS is also useful in lowering non-neuropathic pain in several disorders.

Conclusion

Although an emerging set of studies brings new evidence on the therapeutic potential of both LIFUS and HIFUS for managing NP with minor side-effects, we need more controlled clinical trials to conclude about its safety and efficacy.

Clinical Outcomes of Patients with Rheumatoid Arthritis Treated in a Disease Management Program: Real-World Results

Background

Care models can affect the clinical outcome of patients with rheumatic and musculoskeletal diseases.

Objective

We aimed to compare how an innovative model of a rheumatoid arthritis disease-management program can improve the clinical outcomes of patients compared to a conventional assessment approach.

Methods

We performed a retrospective analysis of real-world data from clinical records of a cohort of 5078 patients diagnosed with rheumatoid arthritis who were followed up at the Center of Excellence in Rheumatoid Arthritis vs the clinical outcomes reported in the Colombian National Registry of Rheumatoid Arthritis.

Results

We found significant differences in the diagnosis and follow-up between the specialized Center program and the usual care reported by the Colombian National Registry (p<0.005), including the evaluation of rheumatoid factor, Anti-citrullinated antibodies Disease Activity Score, Health Assessment Questionnaire, number of visits to the rheumatologist, and clinical outcomes measured by the level of disease activity. In addition, when comparing the Center's clinical outcomes - from baseline to the last follow-up, we found an improvement in the level of disease activity, with patients classified in remission increasing from 20.8% to 58.5% (p<0.005), and a reduction in those with high disease activity from 18% to 4.7% (p<0.005).

Conclusion

Real-world evidence showed that patients with rheumatoid arthritis who underwent follow-up under an innovative disease-management model improved their clinical outcomes compared with those patients in a conventional assessment program. These results could suggest a way of improving health policies for patients with rheumatoid arthritis.

Central Nervous System Mechanisms of Nausea in Gastroparesis: An fMRI-Based Case-Control Study

BACKGROUND/AIMS

Nausea is a major complaint of gastroparesis (GP), and the pathophysiology of this condition is poorly understood. Therefore, this study utilized fMRI to investigate the possible central nervous system (CNS) mechanisms of nausea in 10 GP patients versus 8 healthy controls (HCs).

METHODS

Nausea severity was assessed on a 0-10 scale and presented as mean ± SD. Nausea was increased from baseline utilizing up to 30 min of visual stimulation (VS). Functional network connectivity was measured with fMRI at baseline and after 30 min of VS. fMRI data were preprocessed using statistical parametric mapping software. Thirty-four independent components were identified as meaningful resting-state networks (RSNs) by group independent component analysis. The Functional Network Connectivity (FNC) among 5 RSNs considered important in CNS nausea mechanisms was calculated as the Pearson's pairwise correlation.

RESULTS

Baseline nausea score in GP patients was 2.7 ± 2.0 and increased to 7.0 ± 1.5 after stimulation (P < 0.01). In HCs nausea scores did not increase from baseline after stimulus (0.3 ± 0.5). When comparing GP patients to HCs after VS, a significant reduction (P < 0.001) in bilateral insula network connectivity compared to the right insula network was detected. No significant differences in connectivity were noted among the other RSNs. Additionally, the average gray matter volume was non-significantly reduced in the insula in GP patients compared to HC.

CONCLUSIONS

The insula connectivity network is impaired in nauseated GP patients. This phenomenon could explain the susceptibility of GP patients to nausea or may have resulted from a state of chronic nausea.

Barriers towards effective pharmacovigilance systems of biosimilars in rheumatology: A Latin American survey

Purpose

This review summarises the current status of regulatory guidelines for the approval of biosimilars in Latin America and highlights the main barriers to effective pharmacovigilance in this region. We also report results from a survey of Latin American rheumatologists assessing their understanding of prescribing biosimilars and the pharmacovigilance of these drugs.

Methods

We reviewed the current guidelines for the regulatory approval of biosimilars and barriers to effective pharmacovigilance in Latin American countries. Rheumatologists attending the II Pan‐American League of Rheumatology Associations PANLAR Review Course (Biosimilars update) in Lima, Peru were asked to complete a short survey to determine their knowledge of biosimilars.

Results

Many Latin American countries continue to lag behind Europe and the United States in establishing regulatory guidance and effective pharmacovigilance systems for biosimilars. Results from our survey also highlight a lack of awareness regarding the availability of biosimilars, their nomenclature, automatic substitution, and reporting adverse drug reactions because of these drugs.

Conclusions

The main barriers to effective pharmacovigilance in Latin America are the lack of consensus on the interchangeability of reference biologics and biosimilars, and the need for more suitably trained personnel to carry out effective postmarketing pharmacovigilance of biosimilars. Inconsistencies in biosimilar nomenclature make it difficult to adequately trace drugs and record adverse drug reactions associated with their use, creating a barrier to the global pharmacovigilance of biologics.

Challenges for social media editors in rheumatology journals: an outlook

Social media has become a key component of contemporary medicine, and the rheumatology subspecialty is not an exemption. We found that just six of the 40 key peer-reviewed rheumatology journals have found it sensible to incorporate the new appointment of a Social Media Editor-or a similar designation-into their Editorial Boards. We propose that the role of a social media editor is a trinomial: not only a technological work to promote digital engagement but also an activity of ethical guidance and a cultural challenge dealing with worldwide cultural and mindset diversity.

Mexican rheumatology: where do we stand?

The aim of this review was to provide an overall overview of the past, present, and future situations and main challenges that are facing Mexican Rheumatology as a medical subspecialty in the context of their national healthcare system, where a deficit of workforce at the national level coexists with a shortage of specialists in the less-developed southern states of the country and a great surplus of professionals within large metropolitan areas. We also analyzed the prevalence and burden of Rheumatic and Musculoskeletal Diseases (RMDs), the structural composition and distribution of Mexican Rheumatology, and the clinical profile of the Mexican Rheumatologist. Last, we examined comorbidities, education and training programs and one scenario for Mexican Rheumatology wherein the principal main threats and opportunities are determined.

Ultrasound of sacroiliac joints in spondyloarthritis: a systematic review

Ultrasound (US) is an accessible imaging technique with a possible role to diagnose active sacroiliitis, so this technique is projected as a promising diagnostic tool for the diagnosis of SpA. We analyse the available evidence about the use of US as a diagnostic tool in sacroiliitis in patients with SpA, by a systemic review of the literature fulfilling OMERACT criteria. A systematic literature search for original articles was carried out using four databases (Medline, Embase, Scopus and Web of Science). Data from studies were included only if participants had SpA and a US examination of sacroiliac joint (SIJ) was performed. The methodological quality of the studies was assessed using QUADAS-2 tool. Thirteen studies were included. All studies were observational, prospective and cross-sectional. In most articles (76.9%), the main US finding compatible with sacroiliitis evaluated was the presence of vascularisation (Doppler signals) with measurements of the resistive index (RI). The sensitivity and specificity analysis were performed in seven studies (58.8%) and were good, with a median of 90 and 89.2%, respectively. The studies showed a positive to moderate a strong correlation between the US and the gold standard but this was optimal only in four studies. In general, the agreement was good in all studies (≥ 0.80). The methods of evaluation of sacroiliitis vary between the studies included. To date, there is not enough evidence to support the use of ultrasound as a diagnostic method for sacroiliitis but it has potential to identify structural lesions at SIJ's level.

[Identificación de fármacos reguladores de la actividad del promotor Egr-1 en fibroblastos humanos transducidos con AdΔegr-1-Luc7]

Introducción

La proteína de respuesta temprana a crecimiento 1 (EGR-1) es un factor de transcripción involucrado en la diferenciación y la proliferación celulares, cuya expresión es regulada por su promotor en respuesta a diversos factores físicos y químicos, y a fármacos. Aquí se describen algunos de los principales efectos de los fármacos esteroides y del factor de crecimiento epitelial 1 (EGF-1) sobre la actividad del promotor, mediante un sistema reportero transducido por el adenovirus AdΔegr-1-Luc7 en fibroblastos primarios humanos.

Método

Los fibroblastos primarios humanos fueron cultivados en pase 5, transducidos con AdΔegr-1-Luc7 y expuestos a betametasona, hidrocortisona, dexametasona, testosterona, beta-estradiol y EGF-1 durante 1, 3 y 6 horas. La actividad de reportero fue cuantificada por luminometría y ajustada a la concentración de proteínas totales.

Resultados

La actividad del promotor en presencia de betametasona, hidrocortisona, dexametasona, testosterona y beta-estradiol fue similar a la actividad basal del promotor a las 1, 3 y 6 horas. El control positivo mostró una actividad 17.8 veces mayor a las 6 horas (p ≤ 0.05). De manera similar, las células expuestas a EGF-1 mostraron una actividad 22.07 veces mayor que las células sin fármaco.

Conclusión

La actividad del promotor Egr-1 en fibroblastos humanos es regulada negativamente por los fármacos esteroides y positivamente por el EGF-1.

Introduction

The early growth response protein (EGR-1) is a transcription factor involved in cell differentiation and proliferation, whose expression is regulated by its promoter in response to various physical, chemical and drug factors. Hereby, we describe some of the main effects of steroid drugs and EGF-1 on promoter activity, through a reporter system transduced by AdΔegr-1-Luc7 in human primary fibroblasts (HPF).

Methods

Human primary fibroblasts transduced with AdΔegr-1-Luc7 were exposed to betamethasone, hydrocortisone, dexamethasone, testosterone, beta-estradiol, and EGF-1 during 1, 3 and 6 h. Reporter assay was quantified by luminometry.

Results

The activity of the promoter in presence of betamethasone, hydrocortisone, dexamethasone, testosterone and beta-estradiol were similar to the basal activity of the promoter at 1, 3 and 6 h. The positive control showed an activity 17.8 folds higher (p ≤ 0.05) at 6 h. EGF-1 showed activity of 22.07 folds greater than cells without drug.

Conclusion

The activity of the EGR-1 promoter in human fibroblasts is negatively regulated by steroid drugs and positively by the EGF-1.

The Benefit of Mirtazapine in the Treatment of Progressive Multifocal Leukoencephalopathy in a Young HIV-positive Patient: A Case Report

Highly active antiretroviral therapy is well-established in the treatment of human immunodeficiency virus (HIV)-positive patients. Nonadherence with therapy regimens often leads to the occurrence of opportunistic infections that further complicate treatment and challenge the treating physician. We report a young HIV-positive patient who suffered from progressive multifocal leukoencephalopathy caused by the human John Cunningham virus and showed objective clinical improvement after adding mirtazapine to the treatment regimen, an observation that is supported by the emerging literature.

Disability in Mexico: a comparative analysis between descriptive models and historical periods using a timeline

Some interpretations frequently argue that three Disability Models (DM) (Charity, Medical/Rehabilitation, and Social) correspond to historical periods in terms of chronological succession. These views permeate a priori within major official documents on the subject in Mexico. This paper intends to test whether this association is plausible by applying a timeline method. A document search was made with inclusion and exclusion criteria in databases to select representative studies with which to depict milestones in the timelines for each period. The following is demonstrated: 1) models should be considered as categories of analysis and not as historical periods, in that the prevalence of elements of the three models is present to date, and 2) the association between disability models and historical periods results in teleological interpretations of the history of disability in Mexico.

Neurocysticercosis of the fourth ventricle associated with hydrocephalus

Neurocysticercosis is a parasitic infection of the central nervous system with the cysts of Taenia solium, the pig tapeworm. Infection presents with a pleomorphic picture depending on the stage and location of the infection and the immune response of the infected host. Historically confined to the developing world, neurocysticercosis is no longer limited to endemic regions, as globalization, travel, and immigration permit the spread of the infection. We report a young Hispanic patient who was diagnosed with neurocysticercosis of the fourth ventricle and subsequent hydrocephalus.

Central and Peripheral Effects of Transcutaneous Acupuncture Treatment for Nausea in Patients with Diabetic Gastroparesis

Background/Aims

Nausea, an unpleasant symptom of diabetic gastroparesis (DMGP), has been reported to be alleviated by needleless transcutaneous electrical acupuncture (TEA). Our study was designed to utilize electroencephalography (EEG) and electrogastrography (EGG) recordings to investigate the central and peripheral responses of TEA in the treatment of nausea in DMGP patients.

Methods

Eleven DMGP subjects underwent simultaneous EEG and EGG testing while grading the severity of nausea following 30-minute intervals of: (1) baseline, (2) visual stimulation (VS) to provoke more nausea, (3) active VS together with TEA, and (4) TEA alone, and a final 15-minute recording without any intervention.

Results

The nausea score was increased to 5.9 ± 1.5 with VS (P < 0.05, vs 3.5 ± 1.0 at baseline), then reduced to 3.5 ± 1.2 with VS plus TEA, and to 2.5 ± 1.3 with TEA alone, while it continued at a score of 2.9 ± 1.0 post TEA (all significant, P < 0.05, vs VS without TEA). The mean percentage of normal gastric slow waves was decreased to 60.0 ± 5.7% with VS (P < 0.05, vs 66.6 ± 4.5% at baseline), then improved to 69.2 ± 4.8% with VS plus TEA, and maintained at 70 ± 3.6% with TEA alone. During initial VS, EEG signals showed right inferior frontal activity as the prominent finding, but during VS with TEA, left inferior frontal activity predominated.

Conclusions

In DMGP, TEA improves gastric dysrhythmia and ameliorates nausea. TEA treatment of nausea provoked by VS resulted in a change of dominance from right to left inferior frontal lobe activity. These data provide new understandings of peripheral and central mechanisms for nausea, and potential future directions for DMGP treatment approaches.

First case of isolation of Nocardia wallacei reported in Mexico

Nocardia species are aerobic, Gram-positive bacteria with branched filaments reported as opportunistic microorganisms associated with infectious diseases of the skin. We report the isolation of N. wallacei in Mexico from a 43-year-old man, an HIV-positive construction worker who sought care for difficulty breathing and abundant sputum.

Sinonasal Fungal Infections and Complications: A Pictorial Review

Fungal infections of the nose and paranasal sinuses can be categorized into invasive and non-invasive forms. The clinical presentation and course of the disease is primarily determined by the immune status of the host and can range from harmless or subtle presentations to life threatening complications. Invasive fungal infections are categorized into acute, chronic or chronic granulomatous entities. Immunocompromised patients with poorly controlled diabetes mellitus, HIV and patients receiving chemotherapy or chronic oral corticosteroids are mostly affected. Mycetoma and Allergic Fungal Rhinosinusitis are considered non-invasive forms. Computer tomography is the gold-standard in sinonasal imaging and is complimented by Magnetic resonance imaging (MRI) as it is superior in the evaluation of intraorbital and intracranial extensions. The knowledge and identification of the characteristic imaging patterns in invasive - and non- invasive fungal rhinosinusitis is crucial and the radiologist plays an important role in refining the diagnosis to prevent a possible fatal outcome.

Confirmation of MRI anatomical measurements as endophenotypic markers for bipolar disorder in a new sample from the NIMH Genetics of Bipolar Disorder in Latino Populations study

The main objective of this study is to establish potential neuromorphometric differences which might act as markers of genetic risk for bipolar disorder and therefore serve as endophenotypes for discovery of genes that contribute to bipolar disorder. Magnetic resonance imaging (MRI) was used to assess structural brain volumes of 49 subjects. Volumetric analyses were first performed to test possible differences in the volume of brain structures between subjects with bipolar disorder type I (BPI) and control subjects in a new sample, based on regions previously reported in the literature as being either increased or decreased in size in bipolar patients. Subsequently, for those brain regions showing statistical difference between subjects with BPI and control subjects in our new sample, we tested whether unaffected first degree relatives (UFRs) of the BPI subjects also showed similar differences compared with controls. Four specific regions (right prefrontal, right middle prefrontal, right globus pallidus and left globus pallidus) met criteria for being possible endophenotypes for BPI in this sample.

Probing mechanisms that underlie human neurodegenerative diseases in Drosophila

The fruit fly, Drosophila melanogaster, is an excellent organism for the study of the genetic and molecular basis of metazoan development. Drosophila provides numerous tools and reagents to unravel the molecular and cellular functions of genes that cause human disease, and the past decade has witnessed a significant expansion of the study of neurodegenerative disease mechanisms in flies. Here we review the interplay between oxidative stress and neuronal toxicity. We cover some of the studies that show how proteasome degradation of protein aggregates, autophagy, mitophagy, and lysosomal function affect the quality control mechanisms required for neuronal survival. We discuss how forward genetic screens in flies have led to the isolation of a few loci that cause neurodegeneration, paving the way for large-scale systematic screens to identify such loci in flies as well as promoting gene discovery in humans.

Intensity modulation of TMS-induced cortical excitation: primary motor cortex

The intensity dependence of the local and remote effects of transcranial magnetic stimulation (TMS) on human motor cortex was characterized using positron-emission tomography (PET) measurements of regional blood flow (BF) and concurrent electromyographic (EMG) measurements of the motor-evoked potential (MEP). Twelve normal volunteers were studied by applying 3 Hz TMS to the hand region of primary motor cortex (M1(hand)). Three stimulation intensities were used: 75%, 100%, and 125% of the motor threshold (MT). MEP amplitude increased nonlinearly with increasing stimulus intensity. The rate of rise in MEP amplitude was greater above MT than below. The hemodynamic response in M1(hand) was an increase in BF. Hemodynamic variables quantified for M1(hand) included value-normalized counts (VNC), intensity (z-score), and extent (mm(3)). All three hemodynamic response variables increased nonlinearly with stimulus intensity, closely mirroring the MEP intensity-response function. VNC was the hemodynamic response variable which showed the most significant effect of TMS intensity. VNC correlated strongly with MEP amplitude, both within and between subjects. Remote regions showed varying patterns of intensity response, which we interpret as reflecting varying levels of neuronal excitability and/or functional coupling in the conditions studied.

Column-based model of electric field excitation of cerebral cortex

A model to explain the orientation selectivity of the neurophysiologic effects of electric-field transients applied to cerebral cortex is proposed and supported with neuroimaging evidence. Although it is well known that transcranial magnetic stimulation (TMS) excites cerebral cortex in an orientation-selective manner, a neurophysiologically compelling explanation of this phenomenon has been lacking. It is generally presumed that TMS-induced excitation is mediated by horizontal fibers in the cortical surfaces nearest to the stimulating coil, i.e., at the gyral crowns. No evidence exists, however, that horizontal fibers are orientation selective either anatomically or physiologically. We used positron emission tomography to demonstrate that TMS-induced cortical activation is selectively sulcal. This observation allows the well-established columnar organization of cerebral cortex to be invoked to explain the observed orientation selectivity. In addition, Rushton's cosine principle can used to model stimulation efficacy for an electrical field applied at any cortical site at any intensity and in any orientation.

Identification of Brucella abortus, B. canis, B. melitensis, and B. suis by carbon substrate assimilation tests

By using the results of seven carbon substrate assimilation tests from the Biotype 100 system (bioMérieux, Marcy-l'Etoile, France), we correctly identified 79 (85.9%) of 92 Brucella strains tested. The specificity of the method varied from 97.4 to 100% depending on the species. Although a biological safety cabinet must be used, this method represents an easy and fast alternative for the identification of Brucella species.

Estimation of the percolation thresholds in dextromethorphan hydrobromide matrices

Percolation theory is a multidisciplinary theory that studies chaotic systems. It has been applied in the pharmaceutical field since 1987. Knowledge of the percolation threshold -- one of the most important concepts in percolation theory -- results in a clear improvement of the solid dosage form design. The percolation threshold is the concentration showing the maximum probability to obtain, for the first time, a percolating cluster of a substance. In this work, the percolation thresholds of dextromethorphan.HBr/Eudragit RS-PM inert matrices were estimated. The drug percolation threshold was estimated as 0.3691+/-0.0541 (P=0.05) of the total porosity (ranging between 23 and 36% w/w of drug). The SEM micrographs of the matrices are consistent with the estimated percolation range. In agreement with previous reports, different percolation thresholds were found for the matrix forming excipient Eudragit RS-PM. The site percolation threshold (based on the release properties) ranged between 10 and 20% v/v of the excipient, the site-bond percolation threshold (estimated from the mechanical properties) between 29.5 and 34% v/v of the excipient and the swelling percolation threshold between 34.3 and 46.9% v/v of the excipient. These percolation ranges are in agreement with those found previously for Eudragit RS-PM matrices containing naltrexone.HCl and morphine.HCl.

IgG antibody response to ES or somatic antigens of Dicrocoelium dendriticum (Trematoda) in experimentally infected sheep

The ELISA technique was used to study the kinetics of IgG antibodies against excretory-secretory (ES) and somatic (So) antigens of Dicrocoelium dendriticum in the sera of 32 lambs: 12 experimentally infected with 1,000 metacercariae, 12 with 3,000 and 8 controls. Both antigen types were used at a 2 microg/ml concentration. Dilutions of sera and the anti-sheep IgG peroxidase conjugate were: 1:200 and 1:6,000, respectively. Optical density values for each type of antigen in the two infected groups were higher than the cut-off point from day 30 post infection (p.i.), showing positive infection. Maximum antibody levels were observed 60 days p.i. and remained high until the experiment ended 180 days p.i. This pattern was similar for both ES and So antigens, although with slightly lower figures in the latter. Antibody kinetics were very similar for each of the two doses, except on day 30 p.i. No correlation between the antibody level and parasite burden could be established.

Effects of arsenic exposure on the frequency of HPRT-mutant lymphocytes in a population of copper roasters in Antofagasta, Chile: a pilot study

A pilot biomarker study was conducted to investigate the feasibility of using the hypoxanthine guanine phosphoribosyltransferase (HPRT) gene in peripheral blood lymphocytes as a biomarker for detecting genetic effects of arsenic exposure. Blood and urine samples were obtained from workers highly exposed to arsenic in a copper roasting plant in Antofagasta, Chile. Individuals were classified according to their job titles into three potential exposure groups: high, medium, and low. To confirm exposure, arsenic concentration was determined in urine samples. The HPRT mutant frequencies were measured in lymphocytes from 15 individuals ranging in age from 24 to 66 years. The mean mutant frequencies for the three exposure groups were: low (9 x 10(-6)), medium (11 x 10(-6)), and high (24 x 10(-6)). An increased mutant frequency was observed in the highly exposed group, but the response was so slight that it is not likely that this assay will be capable of providing dose-response information across a range of lower, more typical environmental arsenic levels.