Comparison of blind and electrically guided tracheal needle insertion in human cadavers.

The purpose of this study was to investigate whether an electrically guided needle insertion technique would enable greater success at intratracheal needle tip insertion than the traditional, aspiration-of-air technique. Twenty-seven anaesthesiology residents were assessed in their ability to place a needle tip in the trachea of cadavers using the two methods. Success of needle placement, time to placement and confidence in placement were recorded. Correct intratracheal needle placement was achieved by 22% of residents (6/27) using the aspiration-of-air method vs 82% (22/27) using the electrically guided method (p<0.001). For the instances of success, there was no significant difference between the two methods in the median (IQR [range]) time taken (28 (24-49 [18-63]) s aspiration vs 32 (19-49 [15-84]) s electrical; p=0.93). The electrically guided method provides an acceptably quick and accurate way of placing a needle tip into the tracheal lumen and can be learnt easily by anaesthesiology residents.

Imaging evaluation of potential donors in living-donor liver transplantation.

Liver transplants, originally obtained from deceased donors, can now be harvested from living donors as well. This technique, called living-donor liver transplantation (LDLT), provides an effective alternative means of liver transplantation and is a method of expanding the donor pool in light of the demand and supply imbalance for organ transplants. Imaging plays an important role in LDLT programmes by providing robust evaluation of potential donors to ensure that only anatomically suitable donors with no significant co-existing pathology are selected and that crucial information that allows detailed preoperative planning is available. Imaging evaluation helps to improve the outcome of LDLT for both donors and recipients, by improving the chances of graft survival and reducing the postoperative complication rate. In this review, we describe the history of LDLT and discuss in detail the application of imaging in donor assessment with emphasis on use of modern computed tomography (CT) and magnetic resonance imaging (MRI) techniques.

Anatomic details of intradural channels in the parasagittal dura: a possible pathway for flow of cerebrospinal fluid.

OBJECTIVE: The absorption of cerebrospinal fluid occurs primarily by means of arachnoid granulations (AG) in the superior sagittal sinus (SSS) and the lacunae laterales (LL) in the parasagittal dura. Previous descriptions of this region suggest a network of intradural channels, but finer details of extent and relationship between channels and AG were not addressed. Therefore, we undertook an anatomic study of cadaveric parasagittal dura. METHODS: The SSS and parasagittal dura of 20 formalin-fixed adult cadavers and 15 autopsy specimens from patients ranging in age from 18 weeks of gestation to 80 years were studied by use of a light microscope, a scanning electron microscope, and corrosion casting. Intradural injections into the parasagittal region were performed in two formalin-fixed and four autopsy specimens from adults by use of normal saline and corrosion casting. RESULTS: Extensive networks of intradural channels from 0.02 to 2.0 mm in diameter were noted in all of the specimens. Channels either were connected to the SSS at intervals along the side wall or drained directly into the LL, which extended up to 3 cm from midline. Channels lined with endothelium stained positive for Factor VIII, as did the endothelium of the LL and SSS. In some places, the network of channels seemed to coalesce to form LL. The underside of the dura was coarse and trabeculated where the channels were abundant, and AG were interdigitated between these trabeculae. In regions of the dura where channels were sparse or absent, the dural underside was smooth and lacked AG. Underlying cortical veins opened directly into the SSS and were unrelated to intradural channels. Intradural parasagittal injections from the epidural side accessed the SSS by way of channels using pressures between 0 and 20 cm H2O at 1.5 ml/min. CONCLUSION: These channels may represent a pathway for the flow of cerebrospinal fluid from AG to the SSS.

Effects of sphingosine, staurosporine, and phorbol ester on neurites of rat sympathetic neurons growing in compartmented cultures.

Local application of sphingosine (1-10 microM), an inhibitor of protein kinase C, to NGF-supplied, distal neurites of rat sympathetic neurons in compartmented cultures caused their retraction and/or degeneration within 24 hr. This effect was specific for distal neurites because sphingosine (even at 100 microM) applied to cell bodies and/or proximal neurites did not destroy these regions of the cells, and their distal neurites continued to elongate. However, effects of other agents suggest that the retraction/degeneration observed in distal neurites directly exposed to sphingosine is not mediated by inhibition of protein kinase C: application of staurosporine, another inhibitor of protein kinase C, to distal neurites did not cause retraction or degeneration; treatment of neurons for 24 or more hours with 2 microM phorbol 12-myristate 13-acetate (PMA), used to downregulate protein kinase C activity, slowed neurite extension about 50%, but did not cause degeneration; and neurons pretreated with PMA still displayed retraction/degeneration of neurites when they were subsequently exposed to sphingosine. Also, replacement of NGF supplied to distal neurites with anti-NGF IgG did not cause retraction/degeneration of neurites within 1 d, suggesting that the effect of sphingosine did not arise by interference with the action of NGF. The specificity of the sphingosine-induced retraction/degeneration for distal neurites suggests that this effect operates via specific mechanisms in distal neurites that can trigger their retraction/degeneration. Such mechanisms could play important roles in nerve growth inhibition, nerve fiber retraction, and degeneration that occur normally in the nervous system and in response to injury and disease. Also, the ability of neurites to grow in the presence of PMA suggests that neurite growth is not dependent upon the activity of protein kinase C. However, the reduced rate of neurite extension in the presence of PMA suggests that chronic PMA treatment may affect mechanism(s) that can modulate neurite growth.

Some histological aspects of the hip joint capsule in the vervet monkey.

Microscopic studies show that the capsule of the hip joint in the vervet monkey (Cercopithecus aethiops pygerythrus) is preponderantly collagenous. Among the collagen fiber bundles are varying quantities of elastic fibers that demonstrate a definite, differential regional distribution. The highest concentration of elastic tissue is found in the posterior, postero-inferior, and inferior aspects of the hip joint capsule, whereas the anterior and superior aspects of the capsule are preponderantly collagenous. It is postulated that this regional distribution of elastic tissue is related to the differential functional requirements of the posterior, postero-inferior, and inferior aspects of the capsule for flexibility and stretchability. These requirements appear to be a consequence of the habitual postures and locomotory positions assumed at the hip joint by these primarily quadrupedal primates. Collagen, on the other hand, being much more resistant to deformation and relatively noncompliant, is the predominant tissue in the anterior and superior aspects of the joint.

Segmental variations in the elastic fiber content of the lateral costotransverse ligaments in the vervet monkey (Cercopithecus pygerythrus aethiops).

The segmental and zonal variations in the quantitative relationships between elastic and collagen fibers within the lateral costotransverse ligaments have been investigated in the vervet monkey. The lateral costotransverse ligaments of the caudal segments have a largely elastic structure in contrast to those of the cranial segments, which are characteristically collagenous. In the transitional zone extending from the 4th through to the 6th costotransverse joints, the lateral costotransverse ligaments show a zonal differentiation into a superficial collagenous portion and a deep elastic portion. It is noted that the craniocaudal structural differentiation in the lateral costotransverse ligaments corresponds with similar changes in the vertebral ligaments in that the ligamenta flava gradually extend into the interspinous spaces from the 1st thoracic vertebra (T1) so that at T5 the ligaments occupy 50% of the interspinous space and at T7 the elastic fibers almost completely replace the interspinous ligament. Functionally, however, the regional differences in the elastic fiber content of the lateral costotransverse ligament may have no collateral relationship with the morphology of the ligamenta flava, but are conditioned by movements of the ribs. Whereas movements of the upper six joints are limited by virtue of the configuration of their articular surfaces, which are reciprocally curved, on the 7th to 10th joints the articular facets are almost flat and, therefore, allow considerable movements between the ribs and the corresponding transverse processes.

Structural and functional organization of the suprapatella in two cercopithecines.

Gross and microscopic study of Cercopithecus aethiops pygerythrus and Papio cyanocephalus anubis shows that these cercopithecines have a quadriceps tendon the distal portion of which consists mostly of dense collagenous bundles with scattered fine elastic fibres most of which lie in the loose connective tissue planes within and around the tendon and around blood vessels. A distinct fibrovesicular structure, the suprapatella, lies within the tendon of the vastus intermedius above the pony patella. Histologically, this structure is characterised by interwoven bundles of collagenous fibres, among which are enmeshed large cells containing prominent nuclei surrounded by large clear spaces. It is postulated that this structure facilitates hyperflexion of the knee during the initial phases of springing and jumping.