Biomedical subjects
J H Cook
Publications and source records attributed to J H Cook.
A complication of non-invasive positive pressure ventilation.
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Diagnostic accuracy of film-based, TIFF, and wavelet compressed digital temporomandibular joint images.
The purpose of this research was to determine if digitization and the application of various compression routines to digital images of temporomandibular joint (TMJ) radiographs would diminish observer accuracy in the detection of specific osseous characteristics associated with TMJ degenerative joint disease (DJD). Nine observers viewed 6 cropped hard-copy radiographic films each of 34 TMJs (17 radiographic series). Regions of interest measuring 2 in x 2 in were digitized using an 8-bit scanner with transparency adapter at 300 dpi. The images were placed into a montage of 6 images and stored as tagged image file format (TIFF), compressed at 4 levels (25:1, 50:1, 75:1, and 100:1) using a wavelet algorithm, and displayed to the observers on a computer monitor. Their observations regarding condylar faceting, sclerosis, osteophyte formation, erosion, and abnormal shape were analyzed using ROC. Kappa values were determined for relative condylar size and condylar position within the glenoid fossa. Indices were compared using ANOVA at a significance level of P < .05. Although significant and substantial observer variability was demonstrated, there were no statistically significant differences between image modalities, except for condylar position, in which TIFF and wavelet (at all compression ratios) performed better than the original image. For faceting, wavelet 100:1 performed better than radiographic film images. Little actual image file reduction was achieved at compression ratios above 25:1.
Differential roles of depressive and anxious symptoms and gender in defensiveness.
Among a sample of Air Force cadets facing the prospect of basic training (N= 1,190; 1,005 men and 185 women), the influence of a defensive test-taking style on measures of depressive and anxious symptoms was examined. Participants completed the Beck Depression Inventory (Beck & Steer, 1987) and the Beck Anxiety Inventory (Beck, Epstein, Brown, & Steer, 1988), as well as the MMPI (Hathaway & McKinley, 1943) L scale. Results supported hypotheses that defensiveness would affect a self-report measure of depression but not a self-report measure of anxiety and would do so more among men than women. Applied implications of the results are discussed.
The potential and costs of videoconferencing in dental education, dental vocational training and MFDS preparation.
This paper considers the potential role of videoconferencing technology for postgraduate dental and medical education. Drawing on work from the University of Bristol Dental School, it presents an analysis of the potential cost savings achievable by using videoconferencing compared to traditional face-to-face teaching across a range of scenarios. A summary of the feedback from trainees is also provided.
Effects of anxiety sensitivity on anxiety and pain during a cold pressor challenge in patients with panic disorder.
Fear of anxiety symptoms, or anxiety sensitivity (AS), has been extensively studied in anxiety disorders and more recently has been linked to other psychopathological conditions including pain. Asmundson and colleagues have suggested that AS may act as a risk factor for chronic pain and several studies have demonstrated an association between AS, avoidance behaviors and pain. The present study assessed whether AS levels would be predictive of pain and anxiety during a brief pain induction task. Clinical participants meeting DSM-IV criteria for panic disorder (n = 22) were age and sex matched with nonclinical controls (n = 22) and exposed to a 2-min cold pressor challenge. Diagnostic status and AS were significantly predictive of pain and anxiety during the cold pressor task. Moreover, AS appears to mediate the relationship between diagnostic status and pain. However, AS appears to be only indirectly associated with pain through its contribution to anxiety.
Matching-to-sample deficits in patients with senile dementias of the Alzheimer and Lewy body types.
Using a computerized matching-to-sample task, nonverbal visual recognition memory was studied in two groups of patients suffering from senile dementia of the Alzheimer type or the recently described senile dementia of the Lewy body type. The patients' cognitive abilities had been shown to be similar according to a number of standard psychometric tests. The two groups did not differ with respect to simultaneous matching-to-sample performance, although both were impaired relative to control. The group with senile dementia of the Lewy body type was severely impaired, relative to the group with senile dementia of the Alzheimer type, when delays (delayed matching to sample) were introduced. The findings suggest that short-term mnemonic processes, mediated by temporal lobe structures, could be more severely affected in senile dementia of the Lewy body type.
A comparison of isoflurane and halothane in anaesthesia for intra-ocular surgery.
Isoflurane 0.75% was compared with halothane 0.5% as the volatile supplement in a normocapnic technique for intra-ocular surgery. Both agents gave satisfactory conditions for operation with a comparable reduction in intra-ocular pressure during the procedure. Systolic arterial pressure, however, was significantly lower in the isoflurane group at the end of surgery and after tracheal extubation than in the halothane group. Isoflurane provides a useful alternative to halothane in anaesthesia for intraocular surgery.
Immunologically unique and common domains within a family of proteins related to the retina Ca2+-dependent cell adhesion molecule, NcalCAM.
Rabbit polyclonal antibodies raised to gp90, a fragment of the embryonic chick neural retina Ca2+-dependent adhesive molecule, gp130, recognize gp130 and inhibit Ca2+-dependent cell-cell adhesion. When tested against a panel of 10-day embryonic tissues, one of these antisera recognizes a component with a molecular weight identical to that of gp130 in embryonic chick cerebrum, optic lobe, hind brain, spinal cord and neural retina only; the second antiserum recognizes a similar component in all of the embryonic chick tissues tested. These data imply the existence of an extended family of closely related cell surface components with immunologically distinct subgroups each of which may mediate Ca2+-dependent cell-cell adhesion. As the term CAM, or cell adhesion molecule, has become common usage we propose to refer to these molecules as calCAMs, reflecting their calcium dependence. Analysis of fragments and endoglycosidase digests of NcalCAM have allowed a comparison of its structure with similar molecules from different tissues and species that have been implicated in Ca2+-dependent cell-cell adhesion.
How we won our war with Mr. Goodman.
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Effect of pretreatment with propranolol on intra-ocular pressure changes during induction of anaesthesia.
It is well documented that intra-ocular pressure (IOP) increases following the administration of suxamethonium and also after laryngoscopy and intubation. It is possible that there may be a final common pathway mediated by beta adrenergic transmission which leads to this pressure rise. If so, this mechanism should be inhibited by beta adrenoceptor blockade. Pretreatment with propranolol prevented a significant rise in IOP during a thiopentone, suxamethonium, intubation induction sequence. The change in IOP was even more pronounced during a thiopentone, alcuronium, intubation induction sequence as the base-line IOP was not regained, but there was significant cardiovascular depression. In both these methods the IOP did not remain stable; there was an initial reduction followed by a rise in pressure. Whether these changes in IOP are clinically important remains an open question.
Turnover and orientation of the major neural retina cell surface protein protected from tryptic cleavage by calcium.
Calcium protects a limited number of embryonic chick neural retina cell surface proteins from tryptic cleavage. One glycoprotein of Mr approximately 1.3 X 10(5) and pI approximately 4.8 (gp130) is present in intact retinas and, in the presence of Ca2+, is both resistant to tryptic cleavage and poorly iodinated. When cultured in vitro, iodinated retinas release into the medium a number of iodinated polypeptides; one of the major iodinated components is a polypeptide of Mr approximately 9 X 10(4) and pI approximately 4.8 (gp90). This component is also resistant to tryptic cleavage in the presence of Ca2+. Two-dimensional peptide maps of gp130 and gp90 derived respectively from iodinated retinas and their conditioned media are very similar. Maps of samples reiodinated following denaturation show the same similarities as well as additional labeled peptides. Furthermore, the two-dimensional peptide maps of the two molecules prepared from retinas cultured in the presence of [3H]glucosamine are identical. We conclude that gp90 is a turnover fragment of gp130 and comprises that portion of gp130 exposed at the cell surface. The relevance of these polypeptides to Ca2+-dependent retina cell-cell adhesion and their similarity to polypeptides implicated in Ca2+-dependent adhesion of other cell types are discussed.
Failure of diazepam to prevent the suxamethonium-induced rise in intra-ocular pressure.
The effects of intravenous suxamethonium chloride (1 mg/kg) on intra-ocular pressure (IOP) were studied following pretreatment with diazepam 0.05 mg/kg, tubocurarine 0.05 mg/kg, and in a control group, at induction of anaesthesia. In all three groups, a significant increase in IOP was seen during the induction sequence. In a further study, the effects of intravenous suxamethonium chloride (1 mg/kg) on IOP were studied following a period of stable general anaesthesia and pretreatment with diazepam 0.05 mg/kg. A significant rise in IOP was again seen following the administration of suxamethonium. The authors conclude that neither of the techniques described herein will reliably and predictably prevent the rise in IOP seen following the use of suxamethonium.
The accessibility of certain proteins on embryonic chick neural retina cells to iodination and tryptic removal is altered by calcium.
We have used cell-surface-specific labelling techniques and two-dimensional gel electrophoresis to identify proteins on embryonic chick neural retina cells and to determine the effects of Ca2+ on their accessibility to labelling and tryptic removal. A number of proteins on these cells are, in the presence of Ca2+, relatively inaccessible to iodination and/or tryptic removal. Of these, a glycoprotein of Mr approx. 130 x 10(3), with a pI of approx. 4.8, is the major cell-surface-iodinatable species that is retained during trypsinization in the presence of Ca2+. The removal of Ca2+ renders this glycoprotein much more accessible to both procedures. Its accessibility to these probes decreases on re-addition of Ca2+. The accessibility of its oligosaccharide moiety to galactose oxidase is, however, unaltered by the removal of Ca2+. These characteristics, together with immunological data presented elsewhere suggest that this glycoprotein may be a component of the Ca2+-dependent adhesive system that can be demonstrated on these cells.
The effect of suxamethonium on intraocular pressure.
A method is described of measuring the elevation of the intraocular pressure (IOP) caused by suxamethonium in patients in whom other factors which may cause a change in IOP are kept constant. Use of this method confirms that suxamethonium 1 mg/kg causes a statistically significant rise in IOP which lasts for 10 minutes. A rise in IOP which is not significantly different from this is caused by suxamethonium 2.5 mg/kg, suxamethonium 1 mg/kg immediately preceded by thiopentone 3 mg/kg and by suxamethonium 1 mg/kg, 3 minutes after tubocurarine 0.1 mg/kg.
The practical use of ultrasound as an adjunct to renal calculous surgery.
Removal of small stones and stone fragments from the kidney is difficult and can be an extremely frustrating experience for the surgeon. The major difficulty is the precise localization of the stone within the pelvicalyceal system. Conventional probing of individual calyces is unreliable, even with optimal exposure and direct visualization of the infundibula, using the extended pyelotomy technique. Intraoperative radiographic techniques can be use reliably to detect small stones and fragments. However, such two-dimensional localization limits their effectiveness. Radiographic methods are also cumbersome and require 10 to 15 minutes for each film. Ultrasonography is repeatable and noninvasive. It is a complementary study that offers precise, three-dimensional localization.
Medical aspects of risk classification (Medical Directors/Actuary Panel).
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A treatment plan for rapid assessment of the patient with massive blood loss and pelvic fractures.
Exsanguinating retroperitoneal hemorrhage secondary to pelvic fractures is a frequent cause of death in the injured pedestrian. Attempts at lowering the mortality from these injuries have led to a variety of suggested treatment modalities, including observation, arterial ligation, or direct suturing of the bleeding sites. Arteriographic embolization is perhaps the newest modality but requires implementation of a rapid and efficient triage and treatment plan. Each of the suggested modalities and the formulation of such a treatment plan are discussed and a case report showing the feasibility of immediate arteriographic embolization as the preferred mode of management is presented.