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Methods for Casting Airways
Published in Joan Gil, Models of Lung Disease, 2020
A wide variety of waxes are available, with a range of melting points. Some workers have used dental waxes, but paraffin wax with a melting point of 60° is satisfactory. Negative wax casts are made in the same way as metal casts, and are similarly used to make positive casts. They are much lighter and much more fragile than metal casts, and need to be handled with great care, but can give excellent results.
Laboratory Procedures and Management
Published in Jeremy R. Jass, Understanding Pathology, 2020
A small tissue specimen may be ‘blocked’ in paraffin wax. The blocks and stained sections prepared from each block will be retained in the laboratory for several decades. The remains of large specimens cannot be stored and are usually cremated after one to two months. Mention has been made of frozen sections for visualising enzymes. Frozen sections can also be prepared, stained with H&E and examined by the pathologist in a few minutes. However, interpretation is compromised by poorer preservation of microscopic detail and frozen material cannot be stored conveniently. Nevertheless, pathologists do examine frozen sections when a rapid diagnosis will clearly be of benefit to the patient. The usual example will be during an operation when the findings of the pathologist will guide the surgeon and directly influence the course of the surgical procedure. This was once a common part of the management of breast cancer. (Nowadays, however, the diagnosis of breast cancer is usually made preoperatively by cytological examination of a fine needle aspirate and the patient participates in the decision regarding mastectomy versus simple removal of the lump.) A practical reason for not performing a frozen section during an operation for breast cancer is that cutting into the cancer during surgery distorts the specimen and makes subsequent interpretation by the pathologist difficult. This may impede informed decision making with respect to any need for further surgery.
Traumatic Carotid Sinus Reflex
Published in Burkhard Madea, Asphyxiation, Suffocation,and Neck Pressure Deaths, 2020
Elke Doberentz, Burkhard Madea
The left and right carotid bifurcations were collected at routine autopsies. The neck organs were dissected in a bloodless situation in situ. In each case the two common carotids, including the carotid bifurcations, were excised. The common carotid was cut 2 cm below the bifurcation and the internal and external carotid arteries were transected 2 cm above the carotid bifurcation. The excised carotid bifurcations surrounded by tissue were fixed in formalin. After fixation, the carotid bifurcations were laminated in thin slices of a few millimetres in the horizontal plane (Figure 25.5). The tissue was embedded in paraffin wax. Haematoxylin-eosin (H&E) and Azan staining were performed. All carotid bifurcations were examined microscopically using a light microscope.
Effect of drug load and lipid–wax blends on drug release and stability from spray-congealed microparticles
Published in Pharmaceutical Development and Technology, 2022
Hongyi Ouyang, Soon Jun Ang, Zong Yang Lee, Tze Ning Hiew, Paul Wan Sia Heng, Lai Wah Chan
Hydrophobic carriers, in particular solid lipids, have been increasingly used to achieve taste-masking, modified-release, and increased stability of drugs. However, there are very limited studies on the use of paraffin wax in oral dosage forms, where it can potentially be used as a hydrophobic matrix material in spray congealing to modify drug release or enhance the stability of drugs. Conventionally, paraffin wax comprises a mixture of n-alkanes, iso-alkanes, and cyclo-alkanes that is obtained from crude oil through high-pressure hydrogenation. It is not commonly employed to develop pharmaceutical dosage forms due to reservations regarding its quality. More recently, pharmaceutical-grade paraffin wax (Ph. Eur/USP-NF) has become available as the Fischer–Tropsch (FT) process is utilized to yield hydrocarbon chains from syngas (Sasol 2022). After subsequent distillation and hydrogenation, paraffin wax of a particular chain length can be produced. One major advantage is that such paraffin wax has higher chemical purity, characterized by linear molecular chains and very low iso-alkane content. This would translate into consistent and predictable properties, ideal for use in pharmaceutical dosage forms. The advent of FT paraffin wax has potentially provided opportunities for its use in drug delivery systems and the interest in this wax for drug encapsulation by spray congealing. A previous study explored its ability to taste mask a bitter drug by exploiting the hydrophobic nature of the wax (Ouyang et al. 2018).
Loss of p27Kip1 leads to expansion of CD4+ effector memory T cells and accelerates colitis-associated colon cancer in mice with a T cell lineage restricted deletion of Smad4
Published in OncoImmunology, 2020
Sung Hee Choi, Emily C. Barker, Kyle J. Gerber, John J. Letterio, Byung-Gyu Kim
For hematoxylin and eosin staining (H&E), excised colons were washed with PBS and fixed in 10% formalin. Samples were embedded in paraffin wax, sectioned, stained with H&E, and examined by light microscopy. For immunohistochemistry (IHC), slides were deparaffinized, and rehydrated and heat-induced epitope retrieval was performed prior to blocking with Peroxidazed 1 (BioCare, PX968) and Rodent Block M (BioCare, RBM961). Slides were incubated with primary antibodies, Ki-67, p27Kip1, and CD3 for 1 hour at room temperature. Antibodies were detected using Rabbit-on-Rodent HRP polymer (BioCare, RMR622) and visualized using the Betazoid DAB chromogen kit (BioCare, BDB2004). The percentage of Ki67 positive cells were assessed on six randomly selected field using a digital eyepiece.
Downregulated hippocampal expression of brain derived neurotrophic factor and tyrosine kinase B in a rat model of comorbid epilepsy and depression
Published in Neurological Research, 2019
Jian Liu, Han-Xiao Zhu, Wan-Li Fu, Xin-Wei Xu, Jun-Zhe Yang, Dan Dai, Yun Li
At the end of the behavioral tests, 5 rats per group were anesthetized with 3.6% chloral hydrate (1 mL/100 g) and transcardially perfused with 50 mL saline followed by 300 ml paraformaldehyde (4% in 0.1 M phosphate-buffered saline [PBS], pH 7.3). For immunohistochemical analysis, rat brains were rapidly dissected, and the coronal region containing the hippocampus and associated areas was fixed in paraformaldehyde (4% in 0.1 M PBS, pH 7.3) for 24 h. The tissue samples were then immersed in paraffin wax according to a routine histological protocol and sectioned. Serial sagittal sections of the hippocampus were sliced at 5 μm on a paraffin slicer and mounted on gelatin-pretreated slides for the following laboratory procedures.