Characterization of Multidrug-Resistant Staphylococcus aureus Isolates and Comparison of Methods of Susceptibility to Vancomycin.

S. aureus are among the main bacteria causing problems related to multidrug resistance in nosocomial infections. Therefore, it is necessary to carry out a reliable and rapid diagnosis for the identification of the bacteria and characterization of its susceptibility profile, especially vancomycin, which is an alternative treatment against multidrug-resistant (MDR) S. aureus. Thus, the goal of this study was to characterize isolates of S. aureus regarding the resistance and virulence and to check the susceptibility to vancomycin, through different methods, for comparative purposes. Seventeen antimicrobials were tested to assess the susceptibility profile. It was evaluated the presence of identification (nuc), resistance (mecA and blaZ), biofilm (icaA and icaD) and siderophore (sfaD and sbnD) genes. The susceptibility to vancomycin was evaluated by Minimum Inhibitory Concentration (MIC) by broth microdilution (BMD), E-test, commercial panel (Kit), and Phoenix equipment. Most S. aureus (93,33%) was classified as MDR. These isolates were 100% positive for nuc, mecA, icaA, icaD, and sfaD genes; 96.67% for sbnD and 33.33% for blaZ. In relation to BMD, all methods correctly classified the susceptibility of the isolates; however, regarding the exact MIC value for vancomycin, Phoenix showed agreement of 63.33%, E-test (33.33%) and Kit (26.66%). In conclusion, most of S. aureus was considered MDR. Also, they presented resistance, biofilm production, and siderophores genes, showing the pathogenic potential of these bacteria. Besides, the Phoenix test was considered the most effective, as it presents advantages, such as identification of the microorganism and a greater number of antimicrobials tested at a time.

Mutation frequencies of GNAQ, GNA11, BAP1, SF3B1, EIF1AX and TERT in uveal melanoma: detection of an activating mutation in the TERT gene promoter in a single case of uveal melanoma.

BACKGROUND: Uveal melanoma is the most frequent primary tumour of the eye. It is molecularly clearly distinct from cutaneous melanoma and shows a different pattern of driver mutations. The influence of sunlight ultraviolet (UV) exposure on the aetiology of uveal melanoma is a matter of debate. The recent identification of driver mutations in the promoter of the telomerase reverse transcriptase (TERT) gene with UV-induced cytidine-to-thymidine transitions in cutaneous melanoma prompted us to investigate whether these mutations also occur in uveal melanoma. METHODS: We analysed 50 cases of uveal melanoma obtained from enucleation surgery for mutations in the genes GNAQ, GNA11, BAP1, SF3B1, EIFAX1 and TERT, measured gene expression using microarrays and analysed gene copy numbers by SNP arrays. RESULTS: We detected a TERT mutation in only one case of a 57-year-old white male patient with clinical and histopathological features typical for uveal melanoma. The tumour showed mutations in GNA11 and EIF1AX that are typical for uveal melanoma and absent from cutaneous melanoma. No mutations were detected in GNAQ, BAP1 and SF3B1 that are frequently mutated in uveal melanoma. Both copies of chromosome 3 were retained. Several tumours among which the one carrying the TERT promoter mutation showed elevated TERT expression. Consistent with previous reports, GNAQ is inversely associated with chromosome 3 monosomy and metastasis. BAP1 mutations are significantly associated with chromosome 3 monosomy but not with relapse. CONCLUSION: These data indicate that TERT mutations are rare in uveal melanoma. No conclusion can be drawn on their potential influence on tumour progression.

Effect of Plate Configuration in the Primary Stability of Osteotomies and Biological Reconstructions of Femoral Defects: Finite-Element Study.

BACKGROUND/OBJECTIVE: Osteosynthesis is an alternative treatment for stabilizing femur-bone traumas. The initial stability of the fixation systems is one of the biomechanical parameters affecting implant failure and bone union, especially in surgeries of intercalary reconstructions after the removal of bone tumors. This study aimed to investigate the initial biomechanical effect of using one or two osteosynthesis plate configurations for femoral fixation and the effect of fastening the allograft to the osteosynthesis plate in the case of femoral allograft reconstructions. METHODS: Three finite-element models of a femur with three different fixation conditions for a transverse osteotomy in the middle of the diaphysis, i.e., using one and two osteosynthesis plates and an intercalary allograft, were constructed. An eight-hole compression plate and a six-hole second plate were used to simulate osteosynthesis plates. The plate screws were tightened previously to the loading, and the tightening sequences simulate the bolt-tightening procedure in a surgical environment. The models were imported into the ADINA System for nonlinear analysis, using compression loads applied over the femur head. RESULTS: Models with the dual fixation systems had the most outstanding compression stiffness. The femur head movement in the dual plate system was 24.8% smaller than in the single plate system. A statistical analysis of a region of interest (VOI) placed in the femur diaphysis showed that the biomechanical effect of using the dual plate system is smaller in the osteotomy region than at the femur head, e.g., a displacement average decrease of only 5% between the two systems, while the maximum value decreases by 26.8%. The allograft fixation to the second osteosynthesis plate leads to an improvement in the system stability. CONCLUSIONS: The results presented in this work show that including the bolt analysis in the femoral diaphysis osteotomy fixation will allow for capturing the nonlinear behavior of the osteotomy region more realistically. The stability of the intercalary reconstruction of the femoral diaphysis was higher when the allograft was fastened to the second osteosynthesis plate.

Mechanisms modulating foam cell formation in the arterial intima: exploring new therapeutic opportunities in atherosclerosis.

In recent years, the role of macrophages as the primary cell type contributing to foam cell formation and atheroma plaque development has been widely acknowledged. However, it has been long recognized that diffuse intimal thickening (DIM), which precedes the formation of early fatty streaks in humans, primarily consists of lipid-loaded smooth muscle cells (SMCs) and their secreted proteoglycans. Recent studies have further supported the notion that SMCs constitute the majority of foam cells in advanced atherosclerotic plaques. Given that SMCs are a major component of the vascular wall, they serve as a significant source of microvesicles and exosomes, which have the potential to regulate the physiology of other vascular cells. Notably, more than half of the foam cells present in atherosclerotic lesions are of SMC origin. In this review, we describe several mechanisms underlying the formation of intimal foam-like cells in atherosclerotic plaques. Based on these mechanisms, we discuss novel therapeutic approaches that have been developed to regulate the generation of intimal foam-like cells. These innovative strategies hold promise for improving the management of atherosclerosis in the near future.

Outcome of ICU survivors: a comprehensive review. The role of patient-reported outcome studies.

Problems survivors face after intensive care unit (ICU) discharge begin while they are still in the ward, where many of their specific problems may run unrecognized, but they assume a heavy weight when they arrive at their homes and face several kind of limitations, from being unable to climb stairs because of weight loss, asthenia, dyspnea or joint stiffness to anxiety, depression or post-traumatic stress disorder. Follow-up consultations have given us a better understanding of these specific problems, and the information gained has been used to improve intensive care itself and promote a quality service for patients and relatives. The aim of this article is to provide an overview on adult ICU outcome studies and discuss how they have influenced and improved the delivery of intensive care. We will explain how we went from real patients to outcome studies and what we have learned concerning the consequences of critical illness and critical care. Development of outcome studies, what we have learned through them and our own experience will be outlined focusing mainly in four topics: mortality, physical disability, neuropsychological disability and health-related quality of life. Interventions to improve outcome on these main topics will be presented, and we will explain how we went from outcome studies to clinical interventions, focusing on the most recent proposals of intervention to improve outcome.

A blind algorithm for reverberation-time estimation using subband decomposition of speech signals.

An algorithm for blind estimation of reverberation time (RT) in speech signals is proposed. Analysis is restricted to the free-decaying regions of the signal, where the reverberation effect dominates, yielding a more accurate RT estimate at a reduced computational cost. A spectral decomposition is performed on the reverberant signal and partial RT estimates are determined in all signal subbands, providing more data to the statistical-analysis stage of the algorithm, which yields the final RT estimate. Algorithm performance is assessed using two distinct speech databases, achieving 91% and 97% correlation with the RTs measured by a standard nonblind method, indicating that the proposed method blindly estimates the RT in a reliable and consistent manner.

Comparison of the antibacterial effect of modified 3-mix paste versus Ultrapex over anaerobic microorganisms from infected root canals of primary teeth: an in vitro study.

OBJECTIVE: The aim of this study was to evaluate in vitro the antimicrobial efficacy of a modified 3-mix paste and to compare it with an iodoform paste (Ultrapex) against anaerobic microorganisms isolated from root canals of infected or necrotic primary teeth. STUDY DESIGN: An in vitro experimental assay was performed over isolated and identified anaerobic microorganisms of 21 samples, in order to compare the antimicrobial ability of both root canal filling materials, using a disc-diffusion method. RESULTS: A total of 21 microbial samples (15 polymicrobial and 6 monomicrobial) were obtained, from which 19 different strains were identified. Modified 3-mix paste showed an excellent antimicrobial effect against most of both kinds of microbial samples, although some of them exhibited resistance; on the other hand, Ultrapex showed only minimal antimicrobial ability (null or low categories). Clostridium ramosum exhibited the most resistance to both materials. CONCLUSION: The bactericidal effect of the modified 3-mix paste was superior to Ultrapex, with a statistically significant difference, against anaerobic microorganisms isolated from infected root canals of primary teeth.

Latin American Consensus on management of residual cardiometabolic risk. A consensus paper prepared by the Latin American Academy for the Study of Lipids and Cardiometabolic Risk (ALALIP) endorsed by the Inter-American Society of Cardiology (IASC), the International Atherosclerosis Society (IAS), and the Pan-American College of Endothelium (PACE).

BACKGROUND: Hypertension, hyperglycemia, dyslipidemia, overweight, obesity, and tobacco (smoking, chewing, and vaping), together with a pro-inflammatory and procoagulant state, are the main risk factors related to atherosclerotic cardiovascular disease. OBJECTIVE AND METHODS: A group of experts from the Americas, based on their clinical expertise in cardiology, cardiovascular prevention, and cardiometabolic (CM) diseases, joined together to develop these practical recommendations for the optimal evaluation and treatment of residual CM risk factors in Latin America, using a modified Delphi methodology (details in electronic TSI) to generate a comprehensive CM risk reduction guideline, and through personalized medicine and patient-centered decision, considering the cost-benefit ratio The process was well defined to avoid conflicts of interest that could bias the discussion and recommendations. RESULTS: Residual risk reduction should consider therapeutic options adapted to specific patient needs, based on five treatment objectives: triglyceride-rich lipoproteins, inflammation, impaired glucose metabolism, high blood pressure, and prothrombotic status. Comprehensive control of all CM risk factors should be a priority to deal with this important public health problem and prevent premature deaths. The recommendations in this paper address the evidence-based treatment of CM risk and are intended for clinical application in Latin American countries.

Antecedentes: Un grupo de factores de riesgo cardiometabólicos (hipertensión, hiperglucemia, dislipidemia, sobrepeso, obesidad y tabaco (fumado, masticado, vaporizado), junto con un estado proinflamatorio y procoagulante, son los principales factores de riesgo relacionados con la enfermedad cardiovascular aterosclerótica. Objetivo y métodos: Basándose en su experiencia en cardiología, prevención cardiovascular y enfermedades cardiometabólicas, un grupo de expertos de las Américas se unió para desarrollar estas recomendaciones prácticas para la evaluación y tratamiento óptimos de los factores de riesgo cardiometabólicos residuales en América Latina, utilizando una metodología Delphi modificada con el objetivo de generar una guía integral de pautas para la reducción del riesgo cardiometabólico, mediante la medicina personalizada y la decisión centrada en el paciente teniendo en cuenta la relación costo-beneficio. El proceso fue bien definido para evitar conflictos de intereses que podrían sesgar la discusión y las recomendaciones. Resultados: La reducción del riesgo residual debe considerar opciones terapéuticas adaptadas a las necesidades específicas del paciente, basadas en 5 objetivos de tratamiento: lipoproteínas ricas en triglicéridos inflamación, metabolismo de la glucosa, presión arterial alta y estado protrombótico. El Control integral de todos los factores de riesgo cardiometabólicos debe ser una prioridad para hacer frente a este importante problema de salud pública y prevenir las muertes prematuras. Las recomendaciones de este documento abordan el tratamiento basado en evidencia del riesgo cardiometabólico y están destinadas a la aplicación clínica en los países de América Latina.

Reduction in bacterial loading using 2% chlorhexidine gluconate as an irrigant in pulpectomized primary teeth: a preliminary report.

OBJECTIVE: The aim of this study was to evaluate the reduction in bacterial loading using 2% chlorhexidine gluconate as an irrigating solution in pulpectomized primary teeth. STUDY DESIGN: A randomized, controlled clinical trial was performed that included primary teeth with pulp necrosis. Forty necrotic teeth were included, 20 irrigated with 2% chlorhexidine gluconate (experimental group) and 20 with sterile saline solution (control group); in all cases, 2 microbiological samples from within the canals were taken with sterile paper points, the first after the canal opening and before the first irrigation, and the second after instrumentation and final irrigation, before filling. All samples were evaluated by McFarlands scale. RESULTS: The results were statistically analyzed by the Mann-Whitney U test. After analyzing samples before and after irrigation in the control group (saline), we found a significant decrease of bacterial load (P < 0.0002). The same occurred in the chlorhexidine group samples (P < 0.0001). When both groups were compared post-irrigation, a statistically significant difference was observed in favor of 2% chlorhexidine gluconate. CONCLUSION: Two percent chlorhexidine gluconate showed a greater reduction of intracanal bacterial loading compared with that observed with sterile saline solution. This irrigating solution is suggested as an alternative for pulpectomy of necrotic primary teeth.

Feasibility, tolerability, and safety of hysterosalpingo-foam sonography (hyfosy). multicenter, prospective Spanish study.

OBJECTIVE: To determine the feasibility,tolerability, and safety of the ultrasound assessment of tubal patency using foam as contrast. METHODS: This was a prospective multicenter study of 915 infertile nulliparous women scheduled for sonohysterosalpingography with foam instillation (HYFOSY) for tubal patency testing as a part of the fertility workup. Clinical and sonographic data were recorded into a web-shared database. Tubal patency, cervical catheterization, pain during the procedure and post-procedural complications were collected. Patients reported discomfort or pain experienced during the procedure with a visual analogue scale (VAS) score. RESULTS: Nine hundred fifteen women were included in the final analysis. Median age was 34 (range, 21-45) years and median body mass index was 23 (range, 16-41) kg/m2. Of 839 women, only 8(0.95 %) cases were abandoned due to impossibility of introducing the intracervical catheter. Most of the cervical os were easily cannulated with either paediatric nasogastric probes or special catheter for intrauterine insemination / sonohysterosalpingography 688/914(75.3 %). With a median instillation of 4 mL (range 1-16) of foam, both tubes were identified in 649/875 (70.9 %) patients, while unilateral patency was observed in 190/875 (20.8 %). Only 36/875 (3.9 %) of the women had bilateral tubal obstruction. The median VAS score for perception of pain during HyFoSy examination was 2 (range 0-10), and only 17 (1.9 %) of women reported severe pain (VAS ≥ 7). Pain was unrelated to tubal patency or tubal blockage. Unexpectedly, difficult cervical catheterizations that needed tenaculum, were more likely associated with mild pain during procedure [nasogastric probe group 176/289 (70.9 %) vs. insemination catheter group 166/399 (41.6 %) vs. tenaculum group 190/218(87.2 %) p < 0.001]. Finally, among 915 patients, we only noticed 3 (0.32 %) complications of the technique: two vasovagal episodes and a mild urinary infection. CONCLUSION: HYFOSY is a feasible, well-tolerated and safe technique for the evaluation of tubal patency in infertile women.

Comparison of three DNA extraction methods for Mycobacterium bovis, Mycobacterium tuberculosis and Mycobacterium avium subsp. avium.

AIMS: To compare three methods for DNA extraction from Mycobacterium bovis, Mycobacterium tuberculosis and Mycobacterium avium subsp. avium. METHODS AND RESULTS: The DNA was extracted from mycobacterial cultures using enzymatic extraction, combined bead beating and enzymatic extraction and cetyltrimethylammonium bromide (CTAB) extraction. The yield and quality of DNA were compared by spectrophotometry, agarose gel electrophoresis, restriction endonuclease analysis and PCR. The combined bead beating and enzymatic extraction method yielded more DNA. However, that method produced some sheared DNA, visible either by agarose gel electrophoresis or by restriction endonuclease analysis. All methods were appropriate for PCR amplification of a 123 bp fragment of IS6110 in M. bovis and M. tuberculosis, and of a 1700 bp fragment of FR300 region in M. avium avium. CONCLUSIONS: Combined bead beating and enzymatic extraction method was the most efficient and easy method for extracting DNA from bacteria of the M. tuberculosis complex. SIGNIFICANCE AND IMPACT OF THE STUDY: The results reveal important differences among the DNA extraction methods for mycobacteria, which are relevant for the success of further downstream molecular analysis.

Blood COX-2 and PGES gene transcription during the peripartum period of dairy cows with normal puerperium or with uterine infection.

In the dairy cow, puerperal uterine intra-luminal concentrations of PGE(2) are related to the establishment and severity of uterine infections. Here we evaluated whether the blood concentrations of PGE(2) and the gene transcription profiles of enzymes involved in its synthesis (cyclooxygenase-2 and prostaglandin E synthase) could be used as markers of predisposition and/or presence of puerperal uterine infections. We also studied the relationship between the endocrine status and the leukocyte profiles around parturition and the transcription patterns of the genes. Finally, we have characterized the in vitro gene transcription and expression response to a challenge of LPS. Gene transcription profiles, quantified by real-time PCR, were similar in normal puerperium and metritis/endometritis cows, indicating that they are not suitable markers of predisposition to/presence of puerperal uterine infections. Transcription decreased from 2 weeks before parturition until parturition, when a minimum was attained, and then increased during the first week postpartum. The lowest gene transcription, at parturition, was coincidental with the highest total leukocytes, polymorphonuclear neutrophils and CD14 positive cell numbers. It is suggested that by this mechanism, a large number of PMN can be recruited into the uterus after parturition, avoiding an excessive acute inflammatory response. The lowest gene transcription was also coincidental with the surge in cortisol concentrations, indicating that this hormone plays a main immunomodulatory role around parturition. Gene transcription was significantly greater after stimulation with LPS than in non-stimulated blood. We suggest that this PGE(2) producing cells might arrive to the uterine lumen, contributing to the local PGE(2) concentrations and mediating the inflammatory response.

Treatment of massive pulmonary thromboembolism with low intrapulmonary dosages of urokinase. Short-term angiographic and hemodynamic evolution.

Sixteen patients who had massive pulmonary thromboembolism and shock had no history of cardiopulmonary disease. We present an evaluation of the short-term effects of fibrinolytic treatment consisting of intrapulmonary administration of a bolus of 500,000 IU of urokinase followed by infusion of 1 x 10(6) IU into the right auricle over 12 h and subsequent intravenous infusion of heparin. For each patient, the effectiveness of treatment was evaluated by comparing pretreatment angiographic and hemodynamic parameters with those measured 48 h after the start of treatment. The Miller index fell from 22.9 +/- 5.9 to 9.8 +/- 3.3 (p less than 0.001), with a mean improvement of 57.2 percent. All the hemodynamic parameters studied (cardiac output and index, total pulmonary vascular resistance, and systolic, diastolic, and mean pulmonary vascular pressure) also exhibited statistically significant differences between pretreatment and posttreatment values (p less than 0.001 for each parameter), with a mean improvement of over 30 percent in each case. All the patients survived, and in no case did treatment fail; only one patient (6.2 percent) suffered severe hemorrhage. We conclude that this form of administration of urokinase is useful for patients with critical massive pulmonary thromboembolism.

Phosphate starvation affects the synthesis of outer membrane proteins in Thiobacillus ferrooxidans.

The outer membrane protein (omp40) component from the chemolithoautotrophic acidophilic Thiobacillus ferrooxidans is apparently regulated by the external pH and the concentration of phosphorus. Its amino-terminal sequence showed little identity with the Escherichia coli OmpC, OmpF or PhoE porins, but was 38.5% identical to the outer membrane channel-forming protein NosA from Pseudomonas stutzeri, whose expression is also regulated environmentally. In addition, the partial amino acid sequence of T. ferrooxidans omp40 showed between 34 and 38% identity with the amino-terminal end of the small outer membrane proteins Rck and PagC from Salmonella typhimurium and OmpX from Enterobacter cloacae.

Chemotaxis of Leptospirillum ferrooxidans and other acidophilic chemolithotrophs: comparison with the Escherichia coli chemosensory system.

Ni2+, Fe2+ and Cu2+ were attractants and aspartate was an apparent repellent for Leptospirillum ferrooxidans, a behaviour opposite to that for Escherichia coli. Membranes from L. ferrooxidans contained proteins with a molecular mass in the range of 80 kDa which were methylated in vitro. Methylation was stimulated in the presence of a membrane-free extract from E. coli, showing the response pattern expected for L. ferrooxidans, increased methylation by Ni2+, and demethylation by aspartate. This suggests the existence of sensory transducers having a common methylation domain with the E. coli methyl-accepting chemotaxis proteins. Total chromosomal DNA digests from L. ferrooxidans, Thiobacillus ferrooxidans and T. thiooxidans hybridized with probes containing different domains of the tar gene from E. coli, implying the presence of tar type genes in the acidophilic bacteria studied.

Effect of maternal delta 9-tetrahydrocannabinol on developing serotonergic system.

In this study we investigated the effects of maternal delta 9-tetrahydrocannabinol on the developing serotonergic system. A daily dose of delta 9-tetrahydrocannabinol (5 mg/kg body weight) was administered p.o. to pregnant rats from gestational day 5 to postnatal day 1. Levels of indolamines were measured in four brain areas of the offspring on the day before or after birth. Levels of indolamines depended on the cerebral area, sex and pre- or postnatal age. Maternal exposure to delta 9-tetrahydrocannabinol decreased diencephalic levels of 5-hydroxytryptamine (5-HT), males being more susceptible than females. These perinatal changes could be responsible for the long-term neurophysiological alterations produced by cannabinoids.

Screening of obstructive sleep apnoea: heart rate spectral analysis of nocturnal pulse oximetric recording.

Using heart rate spectral analysis of nocturnal pulse oximetry, we prospectively evaluated the utility of this methodology in patients clinically suspected of having obstructive sleep apnoea (OSA). A hundred and ninety-seven outpatients referred with symptoms compatible with the diagnosis of OSA were studied. All participants had nocturnal pulse oximetry performed simultaneously with conventional polysomnography. Power density of heart rate obtained by nocturnal pulse oximetry was analysed using fast Fourier transformation of a Hamming-windowed signal. Recording test results were classified as abnormal (suspicion of OSA) in the presence of a peak in the periodogram between period boundaries 30-70 sec. A normal test result was defined as the absence of the 30-70 sec peak in the periodogram. The total area of the periodogram (S(TOT)), the area enclosed in the periodogram between the period boundaries 30-70 sec (S(30-70)), the area enclosed in the period boundaries 30-70 sec with respect to the total area of the periodogram (S) and the peak amplitude 30-70 sec (PA) were measured. The presence of a peak in the periodogram has a sensitivity of 81.3%, a specificity of 91.5% a positive predictive value of 89.1% and a negative predictive value of 85.1% for OSA diagnosis. The OSA patients were found to have higher values of S(TOT), S(30-70), S and PA than the non OSA patients. Receiver operating characteristics (ROC) curve was constructed at different thresholds of S(TOT), S(30-70) S and PA. For a PA threshold of 10(%)2, heart rate spectra analysis sensitivity for OSA was 58% and specificity was 92%. Furthermore, the positive and negative predictive values for diagnosis of OSA were 87 and 72% respectively. Apnoea hypopnea index (AHI) correlated significantly with S(TOT) (r=0.44; P<0.001), S(30-70) (r=0.59: P<0.001), S (r=0.58; P<0.001) and PA (r=0.58; P<0.001). According to our results, heart rate spectral analys s obtained by nocturnal pulse oximetry and identification of peak in the periodogram between period boundaries 30-70 sec could be useful as a diagnostic technique for OSA patients.

Pulmonary absorption studies utilizing in situ rat lung model: designing dosage regimen for bronchial delivery of new drug entities.

The absorption of 7-methylsulfinylxanthone-2-carboxylic acid, 7-(methylthio)xanthone-2-carboxylic acid, and their sodium salts from the respiratory tract of anesthetized rats was studied after intratracheal administration of 0.1 ml of a solution or suspension containing the drug. At various times after administration, the lungs and trachea were removed and assayed radiochemically for unabsorbed drug. Sodium 7-(methylthio)xanthone-2-carboxylate from solution was absorbed approximately 20 times faster than sodium 7-methylsulfinylxanthone-2-carboxylate from a solution. The absorption from solutions was three to four times faster than the absorption from suspensions. For inhalation aerosol dosage forms intended for prophylactic use, the drug entity with slower systemic absorption probably would be more desirable than the drug entity with rapid absorption. Rapid systemic absorption following inhalation of powder or liquid aerosols would lead to more frequent dosing if the biological activity is related to the drug concentration in the tracheobronchial tissues. Therefore, the powder or liquid inhalation aerosols of organic acids rather than the corresponding sodium salts may be preferable for designing a dosage regimen. However, if the dosage form is intended for utilizing the bronchodilator activity of the compound, the drug entity with rapid absorption is more desirable. Therefore, in the treatment of asthmatic attacks, liquid or powder inhalation aerosols of the sodium salt of the rapidly absorbing drug entity are preferable. The absorption rates were directly proportional to concentration when the initial concentration of sodium 7-methylsulfinylxanthone-2-carboxylate was varied over a 333-fold range. The effect of the pH of the drug solution administered intratracheally to the rat lung indicated a sharp increase in the pulmonary absorption at a pH near the pKa. The results suggested that structurally related xanthones are absorbed possibly by passive diffusion across the lipoidal region of the pulmonary membranes and that the absorption of organic acids and organic electrolytes is mainly controlled by the lipid solubility of the unionized species.