Biomedical subjects
Publications and source records attributed to B M Logan.
In this article, we illustrate and briefly describe a medial approach, in the sagittally sectioned preserved human head, to display all of the cranial nerves, in situ and in continuity. The method has been successfully used by more than six cohorts of our second-year medical students, and can be completed within a 90-min dissecting session.
The main cause of sinus pathology is disease in the middle meatus, therefore, unless nasal drops are deposited in this site they will not be effective. Currently, one of three standard head positions are used by patients for the instillation of nasal drops, 'head back', 'praying to Mecca', and 'Mygind's', all are uncomfortable and only one, Mygind's position, effectively deposits the drops in the middle meatus. In this paper, we review these three positions by utilizing a preserved cadaver head and conducting a simple gravitational flow study using white liquid latex as a nasal drop substitute. We also describe a new fourth 'Ragan' position, on the side, head down, that is effective in consistently delivering nasal drops into the middle meatus and should prove a most comfortable position for patients to adopt.
Dacryocystorhinostomy is the surgical treatment for nasolacrimal blockage. In recent years, the endoscopic approach has become more popular due to the development of nasal endoscopes and the ease of surgery in comparison to the external approach. In order to identify the lacrimal duct during surgery, surgeons insert a light pipe into the lacrimal duct and then drill or chisel the hard bone of the frontal process of the maxilla to remove the bony covering of the sac and duct. It is obvious that knowledge of the anatomy of the lacrimal sac/duct within the nose is essential for the surgeon. The lacrimal apparatus in the nose was studied using 10 cadaveric half-heads (5 males and 5 females) to establish the anatomical landmarks and most accessible part of the lacrimal duct from within the nose. Although there was solid bone covering the whole length of the sac and the duct, the posteromedial aspect of the lower sac and upper duct was covered by the ultra thin lacrimal bone (average thickness 0.057 mm) which was consistently found to be lying immediately anterior to the uncinate process in the middle meatus, thus constituting a "surgical window" (average size 2.5 mm x 7.2 mm) whereby surgical entry into the lacrimal duct becomes relatively easy. The lower part of the lacrimal sac and the upper part of the lacrimal duct can therefore be easily accessed from within the nose by following this anatomical approach, thus avoiding the need to drill or chisel the dense frontal process of the maxilla.
The position, dimension and thickness of the exposed lacrimal bone at the lateral nasal wall in 10 cadaveric half-heads were examined. In all cases, the lacrimal bone at the lateral nasal wall was found to be just anterior to the mid-third of the uncinate process. The average length and width was 7.4 mm and 2.5 mm, respectively. In nine of the 10 half-heads, the lacrimal bone was very thin with an average thickness of 57 mm. In all the cases, the position of the lacrimal passage covered by the lacrimal bone corresponded to the postero-medial aspect of the upper lacrimal duct and the lower lacrimal sac. This study shows that the uncinate process is a reliable landmark for the lacrimal bone in endoscopic nasal surgery. The paper-thin lacrimal bone allows a bone rongeur to infracture through and nibble away the bony covering of the lacrimal sac in a dacryocystorhinostomy.
In bilateral dissections of 68 cadavers, four examples were found unilaterally of variant slips of iliacus and psoas major muscles. In three of them the femoral nerve was pierced by the variant slip. One of these variants was a previously undocumented accessory slip of iliacus, originating from the iliolumbar ligament, passing inferiorly anterior to iliacus, and traversing the femoral nerve; its tendon split to be attached proximally to the lesser trochanter of the femur and distally to an unknown insertion. Such anomalies might cause tension on the femoral nerve resulting in referred pain to the hip and knee joints and to the lumbar dermatomes L2,3 and 4.
Cadaveric material is often used to guide and validate the interpretation of magnetic resonance imaging (MRI) studies. Direct correlation is achieved when the cadaver material is imaged and then directly sectioned in the plane of the image. Indirect correlation, where the cadaveric sections are compared with unrelated in-vivo images, is easier and more commonly used. Technical difficulties associated with the direct method include preservation of form and composition of the tissues, and the choice of the correct location and plane in which to section the cadaver. Using an MRI compatible ruler, designed to assist the direct correlation of MRI and cadaveric sections, we have examined 10 preserved (embalmed) cadaveric knees using different MRI sequences on several occasions. Despite these variations, subsequent sectioning of the cadaveric knees has shown good correlation with the MR images. Of 54 MR images compared with cadaveric sections, anatomical correlation was rated by independent observers as good or perfect in 47 (87%). This new, versatile and simple method can make better use of our preserved human cadaveric material and has potentially wide application; we are now developing it further to assess the technical capabilities of novel imaging sequences.
A photographic technique is described which enables the production of a series of 35 mm transparencies for teaching topographical anatomy from whole body transverse sections. It shows the sequential build-up of a section from an easily identifiable individual structure to the whole, therefore allowing the viewer to identify important areas and key structures within a section more readily.
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A number of analogues of 3-dimethylamino-2-dimethylaminomethyl-1-(4-methoxyphenyl)-1-propanone dihydrochloride (IIa) and related compounds which showed activity against P388 lymphocytic leukemia were prepared, and of the 16 analogues, three met the criterion for activity in this screen. The toxicity of IIa was examined in rats and either a single dose of 25 mg/kg or nine daily doses of 12.5 mg/kg administered by the intraperitoneal route produced marked irritation and damage to the tissue with which it came into contact. Compound IIa did not show significant activity against eight other tumor systems.
Series of 3-dimethylamino-1-aryl-1-propanone hydrobromides (IV) and 3-dimethylamino-2-dimethylaminomethyl-1-aryl-1-propanone dihydrobromides (V) were synthesized. Evaluation of these derivatives against P-388 lymphocytic leukemia growth revealed that two compounds show promise as antineoplastic agents. Compounds of the V series were unstable in phosphate buffer (in contrast to series IV), and when the same nuclear substituent was present in both series of compounds, V was approximately 100 times more active than IV in both the stimulation and inhibition of respiration of mitochondria isolated from rat liver cells. Representatives from both series showed that respiration in mitochondria was affected by changing the pH of the aqueous buffer from 7.4 to 6.9 or 6.4 and by reducing the temperature from 37 degrees to 20 degrees. The compounds showed reactivity toward a biomimetic thiol.