Cell physiological and pathophysiological studies often require information about the elemental composition of intracellular organelles in situ. Electron probe X-ray microanalysis (EPXMA) is one of the few methods by which intracellular elemental content and distribution can be measured simultaneously. While several cryofixation techniques for EPXMA have been utilized on isolated cells, few have been applied successfully to whole tissue in vivo or in situ. A recently developed, commercial, portable, metal-mirror device was used for preserving kidney in situ to determine the intracellular element distribution in proximal tubule cells. Kidneys of male rats were exposed, cryofixed, and analyzed for organelle elemental contents by EPXMA imaging. In addition, some portions of the frozen tissue were prepared for conventional transmission electron microscopy. Proximal tubules were preserved with intact brush borders and open lumens. The quality of preservation of tubule cell organelles varied inversely as a function of depth from the point of first contact with the mirror surface; the best preservation was within 15 microns, while the poorest preservation was deeper than 30 microns. Analysis of EPXMA images from the best-preserved regions revealed that proximal tubule cell cytoplasmic K/Na was approximately 6, cytoplasmic Cl was low relative to other subcellular compartments, and mitochondrial Ca levels were 1.8 nmole/mg dry weight; these observations indicate that the cells were physiologically viable at the time of cryofixation. The advantages of in situ cryofixation by this metal-mirror method include acquisition of organelle elemental content data in vivo, ease of use, reproducibility, portability, applicability to other tissues, and suitability for pathophysiological studies.

Animals↗

PubMedDate not supplied

Analysis of a polytef granuloma mimicking a cold thyroid nodule 17 months after laryngeal injection.

A 65-year-old female who received laryngeal injections with polytef (Teflon) paste for treatment of right vocal cord paralysis first noticed a small, right anterior neck mass 17 months later. Clinically this mass slowly progressed in size and was felt to be a recurrent carotid body tumor, but at surgery, 22 months after injection, a circumscribed nodule on the anterior right lobe of the thyroid was found and histologically diagnosed as a foreign body granuloma. Scanning electron microscopy (SEM) and energy-dispersive x-ray analysis (EDXA) of material in this lesion was identical to that of polytef paste, which is a mixture of pyrolyzed polytetrafluoroethylene and glycerine. The possibility that deaggregated smaller particles in the polytef paste were able to migrate from the injection site resulting in this neck mass is considered.

Female↗

PubMedDate not supplied

Syringe pumps and start-up time: ensuring safe practice.

The start-up time is the delay between starting an infusion pump and the delivery of fluid at the set flow rate. Mechanical slack in syringe pumps can lead to start-up delays of an hour or more at low-flow rates. During this period no medication is delivered to the patient. The causes of the start-up time delay, its implications and methods of minimising the delay are explained.

Documentation↗

PubMedDate not supplied

Venepuncture: best practice.

Venepuncture is the introduction of a needle into a vein to obtain a blood sample for haematological, biochemical or bacteriological analysis. It is the most common invasive procedure undertaken in hospital. This article provides guidance on the theory and practice of venepuncture.

Humans↗

PubMedDate not supplied

The safe removal of central venous catheters.

Many nurses working in general wards and departments are caring for patients with central venous catheters and are increasingly responsible for their removal. This article outlines the basis of good practice and the possible complications, focusing on air embolism.

Bandages↗

PubMedDate not supplied

Prevention of infection in peripheral intravenous devices.

This article focuses on peripheral intravenous cannulation devices as one source of infection. Using the chain of infection, each aspect is explored to help reduce or prevent infection.

Bandages↗

PubMedDate not supplied

Non-heme mechanisms for T1 shortening: pathologic, CT, and MR elucidation.

PURPOSE: To further elucidate the nonparamagnetic effects of T1-relaxation mechanisms in MR imaging. PATIENTS AND METHODS: In 12 patients with lesions having hyperintense signal on T1-weighted spin-echo MR, findings were correlated with autopsy/surgical biopsy in seven cases and/or noncontrast CT scans in 10 cases. RESULTS: Eight of the 10 CT scans demonstrated hyperattenuation in the lesions, indicating mineralization, which correlated with the areas of hyperintense signal on MR. Histologic characterization of the mineralization was accomplished in three cases using four stains; hematoxylineosin, alizarin red S, von Kassa stains for calcium and Perls' iron. The areas of mineralization were homogeneously strongly positive with the calcium stains and only focally weakly positive with the Perls' iron stain. The mineralization was further characterized in all three cases as containing calcium and phosphorus using energy-dispersive x-ray analysis. Four of the 12 cases had either no correlating CT scans (two cases) or the CT showed no hyperattenuating properties to the lesions (two cases). In all four of these cases, microscopic examination showed that the gyriform configuration of the cortical hyperintense signal on T1-weighted images correlated with linear zones of nonhemorrhagic laminar necrosis (cerebral infarction). No mineralization, except for an occasional ferruginated neuron, could be demonstrated with the four histologic stains. Specimen MR imaging of formalin-fixed brain sections in one case demonstrated in vitro the gyriform hyperintense signal seen in vivo. CONCLUSION: Our studies describe and pathologically characterize two associations with T1 shortening in neuroimaging unrelated to the presence of heme: 1) calcification and 2) laminar necrosis in cerebral infarction.

Brain↗