The evolution of bicontinuous polymeric nanospheres in aqueous solution.

Complex polymeric nanospheres in aqueous solution are desirable for their promising potential in encapsulation and templating applications. Understanding how they evolve in solution enables better control of the final structures. By unifying insights from cryoTEM and small angle X-ray scattering (SAXS), we present a mechanism for the development of bicontinuous polymeric nanospheres (BPNs) in aqueous solution from a semi-crystalline comb-like block copolymer that possesses temperature-responsive functionality. During the initial stages of water addition to THF solutions of the copolymer the aggregates are predominantly vesicles; but above a water content of 53% irregular aggregates of phase separated material appear, often microns in diameter and of indeterminate shape. We also observe a cononsolvency regime for the copolymer in THF-water mixtures from 22 to 36%. The structured large aggregates gradually decrease in size throughout dialysis, and the BPNs only appear upon cooling the fully aqueous dispersions from 35 °C to 5 °C. Thus, the final BPNs are ultimately the result of a reversible temperature-induced morphological transition.

Inhaled corticosteroids in persons with HIV infection: not that harmless.

There is a growing group of HIV-seropositive patients at risk for chronic lung disease due to their life style and age. The interaction between certain antiretroviral drugs and corticosteroid inhalation therapy is potentially dangerous but often unrecognised. We present three cases from our HIV-clinic of whom two developed full blown Cushing's syndrome over a short period of time and one presented with asymptomatic hypocortisolaemia due to serious drug interactions between HIV-drugs and inhaled corticosteroids. General practitioners, HIV and chest physicians should all be aware of this potentially life-threatening interaction and the combination of those products should be avoided where possible.

Tuberculosis of the thyroid gland. A case report.

Tuberculosis of the thyroid gland is a very rare condition. A case of a 47-year-old female with a history of a euthyroid multi-nodular goitre is presented. The patient developed hoarseness due to right recurrent laryngeal nerve paralysis, confirmed with indirect laryngoscopy. On repeated ultrasound, volumetric progression of a dominant nodule in the inferior part of the right thyroid lobe was noticed. Fine needle aspiration was inconclusive. Diagnosis was ultimately based on histopathology of the surgical resection specimen.

Relaxivity of liposomal paramagnetic MRI contrast agents.

Paramagnetic liposomes, spherical particles formed by a lipid bilayer, are able to accommodate a high payload of Gd-containing lipid and therefore can serve as a highly potent magnetic resonance imaging contrast agent. In this paper the relaxation properties of paramagnetic liposomes were studied as a function of composition, temperature and magnetic field strength. The pegylated liposomes with a diameter of approximately 100 nm were designed for favorable pharmacokinetic properties in vivo. The proton relaxivity, i.e. the T1 relaxation rate per mmol of Gd(III) ions, of liposomes with unsaturated DOPC phospholipids was higher than those with saturated DSPC lipids. Addition of cholesterol was essential to obtain monodisperse liposomes and led to a further, although smaller, increase of the relaxivity. Nuclear magnetic relaxation dispersion measurements showed that the relaxivity was limited by water exchange. These results show that these paramagnetic liposomes are very effective contrast agents, making them excellent candidates for many applications in magnetic resonance imaging.

Controlled heterocoagulation of platelets and spheres.

We report the controlled heterocoagulation of platelets and spheres, leading to the formation of colloidally stable, anisotropic hybrid particles. Anionically charged, nanosized polymer latex spherical particles were heterocoagulated on the surface of cationically charged hexagonal gibbsite platelets via the adsorption of a single layer of spheres onto both sides of the hexagonal platelets. The latex particles were annealed at a temperature above the Tg of the latex polymer, resulting in a thin polymer layer covering the gibbsite platelets. This heterocoagulation approach enabled the encapsulation of hydrophilic inorganic particles with polymer latexes and the formation of anisotropic hybrid particles.

Tuberculosis of the spine: CT and MR imaging features.

Tuberculosis (TB) remains endemic in most of the developing countries. However, a resurgence of tuberculosis has also been reported in the past decades in developed countries, not only in the lungs, but also in extrapulmonary sites, e.g. the vertebral column. Vertebral TB is most often found in the lower thoracic and upper lumbar regions. Diagnosis is often difficult; clinical findings are usually non-specific and radiologic features may mimic those of other bacterial, fungal, inflammatory and neoplastic diseases. However, recognition and understanding of the radiological findings may help in diagnosis. Two distinct patterns of vertebral tuberculosis may be seen: the classic finding of spondylodiscitis, characterized by destruction of two or more contiguous vertebrae and opposed end plates, disk infection, and commonly a paraspinal mass or collection. The second pattern, increasing in frequency, is a atypical form of spondylitis without disk involvement.The value of CT and MR imaging are discussed in the diagnostic workup of vertebral tuberculosis. A positive culture or histopathologic analysis of CT-guided needle aspiration or biopsy specimens is required in the absence of pulmonary manifestations of tuberculosis for definitive diagnosis and adequate treatment.

Clinical and radiological deterioration in a patient with AIDS.

Paradoxical clinical deterioration of miliary tuberculosis, characterized by pulmonary and abdominal manifestations, is reported in a patient with the acquired immunodeficiency syndrome, after initiation of treatment with highly active antiretroviral therapy. Paradoxical reaction was attributed to partial restoration of cell-mediated immunity related to highly effective antiretroviral therapy. Because tuberculosis has a high prevalence in HIV patients and tuberculosis is often characterized by miliary spreading of disease in these patients, it is important to recognize this phenomenon.

Tuberculosis of the pancreas: MRI features.

OBJECTIVE: The purpose of this study was to describe the MRI features of tuberculosis of the pancreas. CONCLUSION: Pancreatic tuberculosis can be focal or diffuse. If focal, it presents as a sharply delineated mass located in the pancreatic head, showing heterogeneous enhancement. Lesions are hypointense on fat-suppressed T1-weighted images and a mixture of hypo- and hyperintense on T2-weighted images. The appearances of common bile duct and main pancreatic duct are normal. Diffuse involvement is characterized by pancreatic enlargement with narrowing of the main pancreatic duct and heterogeneous enhancement. Signal intensity abnormalities indicating diffuse involvement include hypointensity on fat-suppressed T1-weighted images and hyperintensity on T2-weighted images.

Tuberculous epididymitis associated with abdominal lymphadenopathy (2004:1b).

Although the predominant form of tuberculosis is pulmonary disease, an increasing number of cases with extra-pulmonary involvement have been reported. The diagnosis of extra-pulmonary tuberculosis is often difficult because of its protean clinical manifestations and non-specific laboratory findings. Abdominal lymph node involvement may be present alone or in combination with involvement of the gastrointestinal tract, peritoneum, and solid viscera. Tuberculous epididymitis occurs sporadically and represents a specific secondary subacute or chronic inflammatory process involving the epididymis. We present the imaging findings in a patient with tuberculous epididymitis associated with abdominal tuberculous lymphadenopathy.

The observation of intact hepatic endothelial cells by cryo-electron microscopy.

Liver sinusoidal endothelial cells (LSECs) can optimally be imaged by whole mount transmission electron microscopy (TEM). However, TEM allows only investigation of vacuum-resistant specimens and this usually implies the study of chemically fixed and dried specimens. Cryo-electron microscopy (cryo-EM) can be used as a good alternative for imaging samples as whole mounts. Cryo-EM offers the opportunity to study intact, living cells while avoiding fixation, dehydration and drying, at the same time preserving all solubles and water as vitrified ice. Therefore, we compared the different results obtained when LSECs were vitrified using different vitrification conditions. We collected evidence that manual blotting at ambient conditions and vitrification by the guided drop method results in the production of artefacts in LSECs, such as the loss of fenestrae, formation of gaps and lack of structural details in the cytoplasm. We attribute these artefacts to temperature and osmotic effects during sample preparation just prior to vitrification. By contrast, by using an environmentally controlled glove box and a vitrification robot (37 degrees C and 100% relative humidity), these specific structural artefacts were nearly absent, illustrating the importance of controlled sample preparation. Moreover, data on glutaraldehyde-fixed cells and obtained by using different vitrification methods suggested that chemical prefixation is not essential when vitrification is performed under controlled conditions. Conditioned vitrification therefore equals chemical fixation in preserving and imaging cellular fine structure. Unfixed, vitrified LSECs show fenestrae and fenestrae-associated cytoskeleton rings, indicating that these structures are not artefacts resulting from chemical fixation.

Direct observation of dipolar chains in iron ferrofluids by cryogenic electron microscopy.

A key issue in research on ferrofluids (dispersions of magnetic colloids) is the effect of dipolar interactions on their structure and phase behaviour, which is not only important for practical applications but gives fundamental insight in dipolar fluids in general. In 1970, de Gennes and Pincus predicted a Van der Waals-like phase diagram and the presence of linear chains of particles in ferrofluids in zero magnetic field. Despite many experimental studies, no direct evidence of the existence of linear chains of dipoles has been reported in the absence of magnetic field, although simulations clearly show the presence of chain-like structures. Here, we show in situ linear dipolar structures in ferrofluids in zero field, visualized on the particle level by electron cryo-microscopy on thin, vitrified films of organic dispersions of monodisperse metallic iron particles. On systematically increasing the particle size, we find an abrupt transition from separate particles to randomly oriented linear aggregates and branched chains or networks. When vitrified in a permanent magnetic field, these chains align and form thick elongated structures, indicating lateral attraction between parallel dipole chains. These findings show that the experimental model used is well suited to study the structural properties of dipolar particle systems.

What is the optimal treatment strategy for chronic obstructive pulmonary disease exacerbations?

The present study aims to determine whether treating chronic obstructive pulmonary disease (COPD) exacerbations with intravenous steroids and aerosol bronchodilators (group I) is superior to oral steroids and multiple dose inhaler (MDI) bronchodilators with a spacer (group II). Group I received 40 mg methylprednisolone x day(-1) intravenously with a decrease to 20 mg after 10 days and a further decrease of 4 mg x 4 days(-1). Aerosol therapy consisted of 10 mg salbutamol and 1 mg ipratropiumbromide x day(-1). Group II received 32 mg methylprednisolone orally for 1 week followed by 24 mg x day(-1) for 4 days and a subsequent decrease of 4 mg x week(-1). Duovent MDI with a spacer was given at a dose of 1.6 mg fenoterol and 640 microg ipratropiumbromide x day(-1). In group I (n=19) forced expiratory volume in one second (FEV1) rose from 0.82+/-0.46 to 0.91+/-0.47 L and average dyspnoea decreased from 6.0+/-1.9 to 4.1+/-2.6 within 10 days. The Chronic Respiratory Disease Index Questionnaire (CRQ) score increased from 78+/-24 to 90+/-24 points after 4 weeks. In group II (n=18) FEV1 increased from 0.70+/-0.27 to 0.90+/-0.29 L, dyspnoea regressed from 6.2+/-2.4 to 2.7+/-2.6 and CRQ from 67+/-17 to 86+/-20. Both groups showed similar results in dropout rate, length of hospital stay and patient satisfaction. In conclusion, the two treatment strategies appear equally effective in treating chronic obstructive pulmonary disease exacerbations, although oral steroids and metered dose inhaler bronchodilators appear associated with a higher risk of hospital re-admission.

Association of man-made mineral fibre exposure and sarcoidlike granulomas.

It is assumed that sarcoidosis is caused by inhalation of air borne agents in susceptible persons triggering the inflammatory reaction. The association of metallic dust exposure, such as beryllium and aluminium, and sarcoidlike pulmonary disorders is well known. The ability of man-made mineral fibres (MMMF) to cause granulomatous lung disease has not been appreciated until now. Recently, we observed the association of sarcoidlike granulomatous reaction and occupational history of glass fibre exposure. We hypothesized that there might be a relationship between MMMF exposure and the development of sarcoidlike granulomas. Therefore, the records of 50 sarcoidosis patients-who visited our outpatient clinic between 1996 and 1999 were reviewed. This revealed that 14 cases recalled a history of exposure to either glass fibres or rock wool, both MMMF fibres. The available obtained tissue specimens (n = 12) were reviewed. In six cases electron microscopy qualitative analysis of small fragments of the tissue revealed among others silica, aluminium and sometimes titanium. A distinct relation between fibre deposits fibre deposits and granulomas was found. These findings indicate that in susceptible people MMMF exposure might be related to a chronic granulomatous disease similar to chronic beryllium disease.

Pixe microanalysis of trace elements of normoxic, ischemic and reperfused rat hearts.

With a 3 x 3 mu m(2) proton microbeam spatial distributions of Na, Mg, P, S, K, Ca and Fe were measured via PIXE in 50 x 50 mu m(2) areas of rat heart, sliced into 10-15 mu m thick cryosections. The isolated rat hearts were subjected to normal perfusion, ischemia and reperfusion. Substantial changes in the elemental distribution were found in tissue after 40 min. of reperfusion, particularly indicated by locally elevated Ca and decreased K levels. Electron microscopic examination was used for assessment of artefacts due to sample preparation and handling. Results of stained cryosections analyzed via STIM demonstrated that this latter technique can be employed prior to PIXE analysis to localize individual cells in freeze-dried cryosections.

The procoagulant response of cytomegalovirus infected endothelial cells.

The report describes the effect of an in vitro infection of human umbilical vein endothelial cells with human Cytomegalovirus (CMV). The parameters studied are cellular procoagulant activity, secretion of plasminogen activator inhibitor (PAI-1) and urokinase-type plasminogen activator (u-PA), activation and internalization of factor X and Merocyanine 540 staining. The infection does not result in an increase in PAI-1 and u-PA secretion, but it brings about a procoagulant response, which is relatively rapid compared to the tissue factor mediated response induced by inflammatory mediators. The time course and the coagulation factor dependency suggest a facilitated interaction of coagulation factors on the surface of infected cells. Chromogenic activity measurements after the addition of purified factor X and electron microscopic examination of the cells after addition of colloidal gold-factor X conjugates both point to an internalization of factor X and/or Xa after interaction with the endothelial cell surface. Merocyanine 540 staining suggests that CMV infection leads to membrane perturbations.