The spreading of Covid-19 in Mexico: A diffusional approach.

In this work, we analyze the spreading of Covid-19 in Mexico using the spatial SEIRD epidemiologic model. We use the information of the 32 regions (States) that conform the country, such as population density, verified infected cases, and deaths in each State. We extend the SEIRD compartmental epidemiologic with diffusion mechanisms in the exposed and susceptible populations. We use the Fickian law with the diffusion coefficient proportional to the population density to encompass the diffusion effects. The numerical results suggest that the epidemiologic model demands time-dependent parameters to incorporate non-monotonous behavior in the actual data in the global dynamic. The diffusional model proposed in this work has great potential in predicting the virus spreading on different scales, i.e., local, national, and between countries, since the complete reduction in people mobility is impossible.

Multiple brain abscesses due to Nocardia spp. in an immunocompetent patient / [Abscesos cerebrales por Nocardia spp. en una paciente inmunocompetente].

The infection by Nocardia spp is not common in immunocompetent patients. The empirical antimicrobial treatment directed by anatomical regions does not contemplate the particularities of the germ and the microbiological analysis is necessary for the specific treatment. We present the case of a previously healthy and immunocompetent patient, without known risk factors for Nocardia spp. infection, with evidence of involvement of the pulmonary parenchyma and the skin and subsequent development of multiple brain abscesses.

La infección por Nocardia spp. no es común en pacientes inmunocompetentes. El tratamiento antimicrobiano empírico dirigido según las regiones anatómicas, no contempla las particularidades del germen y el análisis microbiológico se hace necesario para el tratamiento específico. A continuación, se presenta el caso de una paciente previamente sana, inmunocompetente y sin factores de riesgo conocidos para la infección por Nocardia spp., con evidencia de compromiso en el parénquima pulmonar y la piel, que posteriormente desarrolló varios abscesos cerebrales.

Abscesos cerebrales por Nocardia spp. en una paciente inmunocompetente / Multiple brain abscesses due to Nocardia spp. in an immunocompetent patient

La infección por Nocardia spp. no es común en pacientes inmunocompetentes. El tratamiento antimicrobiano empírico dirigido según las regiones anatómicas, no contempla las particularidades del germen y el análisis microbiológico se hace necesario para el tratamiento específico. A continuación, se presenta el caso de una paciente previamente sana, inmunocompetente y sin factores de riesgo conocidos para la infección por Nocardia spp., con evidencia de compromiso en el parénquima pulmonar y la piel, que posteriormente desarrolló varios abscesos cerebrales.

The infection by Nocardia spp is not common in immunocompetent patients. The empirical antimicrobial treatment directed by anatomical regions does not contemplate the particularities of the germ and the microbiological analysis is necessary for the specific treatment. We present the case of a previously healthy and immunocompetent patient, without known risk factors for Nocardia spp. infection, with evidence of involvement of the pulmonary parenchyma and the skin and subsequent development of multiple brain abscesses.

Defining Nutrient Combinations for Optimal Growth and Polyhydroxybutyrate Production by Methylosinus trichosporium OB3b Using Response Surface Methodology.

Methane and methanol are common industrial by-products that can be used as feedstocks for the production of value-added products by methylotrophic bacteria. Alphaproteobacterial methanotrophs are known to produce and accumulate the biopolymer polyhydroxybutyrate (PHB) under conditions of nutrient starvation. The present study determined optimal production of biomass and PHB by Methylosinus trichosporium OB3b as a function of carbon source (methane or methanol), nitrogen source (ammonium or nitrate), and nitrogen-to-carbon ratio during growth. Statistical regression analysis with interactions was performed to assess the importance of each factor, and their respective interactions, on biomass and PHB production. Higher biomass concentrations were obtained with methane as carbon source and with ammonium as nitrogen source. The nitrogen source that favored PHB production was ammonium for methane-grown cells and nitrate for methanol-grown cells. Response surface methodology (RSM) was used to determine conditions leading to optimal biomass and PHB production. As an example, the optimal PHB concentration was predicted to occur when a mixture of 30% methane and 70% methanol (molar basis) was used as carbon source with nitrate as nitrogen source and a nitrogen-to-carbon molar ratio of 0.017. This was confirmed experimentally, with a PHB concentration of 48.7 ± 8.3 mg/L culture, corresponding to a cell content of 52.5 ± 6.3% (cell dry weight basis). Using RSM to simultaneously interrogate multiple variables toward optimized growth and production of biopolymer serves as a guide for establishing more efficient industrial conditions to convert single-carbon feedstocks into value-added products.

Imaging appearances of the sternum and sternoclavicular joints.

The sternum and sternoclavicular joints--critical structures of the anterior chest wall--may be affected by various anatomic anomalies and pathologic processes, some of which require treatment. Pectus excavatum and pectus carinatum are common congenital anomalies that are usually benign but may warrant surgical treatment if they cause compression of vital internal structures. By contrast, developmental variants such as the sternal foramen are asymptomatic and do not require further evaluation or treatment. Arthritides of the sternoclavicular joint (osteoarthritis, septic arthritis, and seronegative arthropathies) are common and must be differentiated before an appropriate management method can be selected. The recognition of complications of sternotomy (eg, sternal dehiscence, secondary osteomyelitis) is critical to avoid life-threatening sequelae such as acute mediastinitis. Likewise, the detection of sternal fractures and sternoclavicular dislocations is important, especially where they impinge on vital structures. In addition, sternal malignancies (most commonly, metastases and chondrosarcoma) must be distinguished from benign neoplasms. To achieve accurate and timely diagnoses that facilitate appropriate treatment, radiologists must be familiar with the appearances of these normal anatomic variants and diseases of the sternum.

Silicone pulmonary embolism: report of 10 cases and review of the literature.

OBJECTIVE: To assess patient outcome and imaging findings of patients with pulmonary embolism of fluid silicone. METHODS: Medical records and imaging examinations of 10 patients with respiratory distress after illicit injection of fluid silicone were reviewed. Population consisted of 8 male (6 male-to-female transsexuals) and 2 female subjects. RESULTS: Average age was 29 years. Most common injection sites were gluteal and trochanteric. Respiratory symptoms developed between 15 minutes and 2 days after silicone injection. Five referred fever, 6 developed adult respiratory distress syndrome, and 2 subsequently died. Alveolar hemorrhage was demonstrated on pathological examination in 6, with silicone vacuoles in the lung parenchyma in 3. Computed tomography demonstrated peripheral ground glass opacities with interlobular septal thickening in all and peripheral airspace disease in 7. CONCLUSIONS: Illicit injection of large volumes of fluid silicone for cosmetic purposes is associated with pulmonary embolism and acute alveolar hemorrhage and is associated with a significant mortality.

Pulmonary complications from cocaine and cocaine-based substances: imaging manifestations.

Cocaine is the illicit drug whose abuse most often results in cardiopulmonary symptoms and emergency treatment. Habitual smoking of alkaloidal cocaine ("freebase," "crack") has replaced nasal insufflation as the most common method of abuse. Smoking of cocaine exposes the lung directly to the volatilized drug as well as to the other combustion products of the smoked mixture, thereby increasing the risk of adverse pulmonary effects. A wide variety of pulmonary complications including interstitial pneumonitis, fibrosis, pulmonary hypertension, alveolar hemorrhage, asthma exacerbation, barotrauma, thermal airway injury, hilar lymphadenopathies, and bullous emphysema may be associated with the inhalation of crack cocaine or of associated substances such as talc, silica, and lactose. Cocaine abuse represents one of the most serious medical and social problems of our time. Radiologists should be familiar with the various pleuropulmonary complications associated with the abuse of illicit drugs in general and of cocaine in particular to ensure correct diagnosis and appropriate treatment planning in patients with respiratory manifestations associated with such abuse.

Imaging manifestations of Kaposi sarcoma.

Kaposi sarcoma (KS) is a low-grade vascular tumor that typically manifests as one of four variants: classic KS, endemic (African) KS, iatrogenic (organ transplant-related) KS, or acquired immunodeficiency syndrome (AIDS)-related KS. Several clinical and epidemiologic differences have been noted among these variants. Classic KS and endemic KS rarely require radiologic evaluation due to their usually chronic course and stability of skin compromise. However, iatrogenic KS and AIDS-related KS, the most common forms of the disease, are frequently disseminated or symptomatic and may thus require imaging studies for both diagnosis and staging. KS is the most common tumor among AIDS patients, affecting a high percentage of these individuals, and is considered to be an AIDS-defining illness. Multiple organs can be involved by AIDS-related KS. KS has been linked with human herpes virus type 8 infection and other cofactors. Although pulmonary, gastrointestinal, and skin involvement by KS has previously been described, this tumor can affect multiple organs, generating a wide spectrum of imaging findings and pathologic correlates. It is important for the radiologist to be familiar with this spectrum of imaging manifestations and corresponding pathologic findings.

Thoracic manifestations of tropical parasitic infections: a pictorial review.

Parasitic infections are distributed worldwide and affect hundreds of millions of individuals-primarily those living in endemic areas or in regions with a high rate of immigration from endemic areas-causing significant morbidity and mortality. A broad spectrum of parasitic infections (eg, amebiasis, malaria, trypanosomiasis, ascariasis, strongyloidiasis, dirofilariasis, cystic echinococcosis, schistosomiasis, paragonimiasis) frequently affect the lungs, mediastinum, and thoracic wall, manifesting with abnormal imaging findings that often make diagnosis challenging. Although most of these infections result in nonspecific abnormalities, familiarity with their imaging features as well as their epidemiologic, clinical, and physiopathologic characteristics may be helpful to the radiologist in formulating an adequate differential diagnosis.