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Biomedical subjects

C Cook

Publications and source records attributed to C Cook.

At least 37 records · Page 2Linked to original sources
PubMed2001

Ultrasound and fluoroscopic-guided angioplasty over the aortic bifurcation in a patient with previous severe reaction to contrast medium.

PURPOSE: To describe a case of ultrasound and fluoroscopic-guided angioplasty necessitated by a patient history of allergic reaction to contrast medium. CASE REPORT: A 60-year-old man with intermittent right leg claudication had a focal >70% stenosis in the right external iliac artery that was amenable to balloon dilation; however, the patient reported a severe reaction to radiographic contrast medium 10 years previously. Angioplasty was begun with transaortic access to the iliac artery lesion under fluoroscopic guidance only. On-table duplex imaging confirmed the lesion site and reference diameters for balloon selection. The balloon was filled with contrast medium to provide rapid positioning under fluoroscopy. An on-table postangioplasty duplex scan showed improvement in the lumen contour and confirmed a reduction in the peak systolic velocity. At the 1-year follow-up, the patient reports no symptoms referable to the treated segment. CONCLUSIONS: The combination of ultrasound and fluoroscopy facilitated quick and efficient balloon dilation of an isolated iliac lesion without the use of any contrast medium.

Angioplasty, Balloon↗
PubMed2001

Calcification on the chest X-ray: a pictorial review.

There are numerous causes of calcification on the chest radiograph. Their striking appearance can lead to anxiety among junior medical staff. This article aims to categorize these appearances, and to give examples of the most common causes seen.

Calcinosis↗
PubMed2001

Pre-operative electrocardiograph examination.

The leading cause of death following surgery is a cardiac event, and an electrocardiogram is the most common pre-operative test to investigate coronary artery disease. Fifty adults, who required an electrocardiogram, undergoing general surgical procedures, were recruited into this pilot study, which investigated the examination rate of electrocardiographs by doctors pre-operatively. Each tracing was folded in one corner and a paperclip prevented full pre-operative viewing without its removal. Results suggest that 30% of ECGs were not opened and the records of 58% patients overall had no mention of the ECG having been performed. Further analysis showed no correlation with the examination rate of the electrocardiograph with patient age or fitness. If this reflects normal clinical practice, it is sub-optimal use of resources and warrants further audit.

Abdomen↗
PubMed2000

Depletion of a microtubule-associated motor protein induces the loss of dendritic identity.

Dendrites are short stout tapering processes that are rich in ribosomes and Golgi elements, whereas axons are long thin processes of uniform diameter that are deficient in these organelles. It has been hypothesized that the unique morphological and compositional features of axons and dendrites result from their distinct patterns of microtubule polarity orientation. The microtubules within axons are uniformly oriented with their plus ends distal to the cell body, whereas microtubules within dendrites are nonuniformly oriented. The minus-end-distal microtubules are thought to arise via their specific transport into dendrites by the motor protein known as CHO1/MKLP1. According to this model, CHO1/MKLP1 transports microtubules with their minus ends leading into dendrites by generating forces against the plus-end-distal microtubules, thus creating drag on the plus-end-distal microtubules. Here we show that depletion of CHO1/MKLP1 from cultured neurons causes a rapid redistribution of microtubules within dendrites such that minus-end-distal microtubules are chased back to the cell body while plus-end-distal microtubules are redistributed forward. The dendrite grows significantly longer and thinner, loses its taper, and acquires a progressively more axon-like organelle composition. These results suggest that the forces generated by CHO1/MKLP1 are necessary for maintaining the minus-end-distal microtubules in the dendrite, for antagonizing the anterograde transport of the plus-end-distal microtubules, and for sustaining a pattern of microtubule organization necessary for the maintenance of dendritic morphology and composition. Thus, we would conclude that dendritic identity is dependent on forces generated by CHO1/MKLP1.

Animals↗
PubMed2000

Organosulfur compounds as pre-exposure therapy for threat agents.

A series of symmetric (Ar-S-S-Ar) and unsymmetric (Ar-S-S-CH2CH2NH3+Cl-) disulfides have been prepared and evaluated as potential cyanoprotective agents. Target compounds have been prepared by known methods and/or methods developed by us specifically for this program, e.g. reaction of a thiol with 2,2'-dithiobis(benzothiazole) (BT-S-S-BT) followed by reaction with a second thiol. Both 4-methoxyphenyl disulfide and 2-aminoethyl-4-methoxyphenyl disulfide hydrochloride are cyanoprotective against 2-LD50 of injected cyanide. Evaluation of both symmetric and unsymmetric related disulfides indicates that structural requirements for cyanoprotective activity are stringent and strongly suggest that protection is enzyme mediated. In addition to cyanoprotective action, initial results suggest that unsymmetric disulfides may evolve into effective antimustard agents.

Disulfides↗
PubMed2000

Telemedicine techniques can be used to facilitate the conduct of multicentre trials.

A multicentre randomized controlled trial was established in Pretoria, Bloemfontein and Edendale in South Africa, and coordinated from London. The purpose of the trial was to determine the efficacy of low-dose beta irradiation of glaucoma. Five communication modalities (telephone, fax, e-mail, videoconferencing and face-to-face meetings) were examined in terms of their benefits in a multicentre trial. The eight stages of the multicentre trial examined were: set-up and training, recruitment, standardization, patient management, data transmission, update and data dissemination, clinical follow-up and monitoring, and publication. On four-point Likert scales for rating the usefulness of the communication modalities at each of the eight stages of the trial (from 0 = not useful to 3 = very useful; maximum score 24) the telephone was given a total score of 10, fax 9, e-mail 13, videoconferencing 15 and face-to-face meetings 9. Telemedicine techniques offer considerable benefits in the coordination of multicentre trials by improving data collection, maintaining the efficacy and monitoring of trials, while potentially offering reduced costs in terms of travel and time. The realtime scrutiny of patient records helps to ensure data uniformity and completeness of data collection. Videoconferencing was most useful when considered as one of several communication tools that can be used to improve the effectiveness of a service or process.

Glaucoma↗
PubMed2000

An artificial neural network for the electrocardiographic diagnosis of left ventricular hypertrophy.

OBJECTIVE: A neural network was constructed to predict the presence of left ventricular hypertrophy (LVH) using both clinical information and the electrocardiogram (ECG). DESIGN AND SETTING: In this retrospective study of 317 adult male patients, clinical parameters were age and history/physical examination: normal, heart failure, LV outflow obstruction, mitral regurgitation or aortic regurgitation. Multiple ECG parameters were used. A back-propagation neural network was constructed. The network was trained on 217 patients. A test set of 100 patients was then evaluated. The network was used to predict both LV mass and LVH by the criterion of LV mass index > 132 g/m2. RESULTS: LV mass was predicted with an accuracy of 79%. In predicting LVH, the network showed 82% correct diagnosis, sensitivity 94%, and specificity 65%. Positive predictive accuracy was 81% and negative predictive accuracy was 89%. CONCLUSIONS: The neural network integrates clinical and ECG data and its resultant prediction of LVH is superior to that obtained using conventional ECG diagnostic criteria.

Diagnosis, Computer-Assisted↗
PubMed2000

Improving the oral hygiene of institutionalized mentally retarded clients.

PURPOSE: The quality of oral health care of persons with mental retardation has been reported in the literature to be less than that of their normal peers. The purpose of this study, set in a Midwest institution for persons with developmental retardation, was to determine if a change in policy followed by staff training and monitored by an interested third party would improve the oral hygiene of clients living on wards. METHODS: Methods used to train staff in proper toothbrushing were developed. Three living units were randomly selected for study: control, training plus accountability (experimental group I), and training without accountability (experimental group II). The direct care staff of both experimental groups were trained in proper toothbrushing techniques. Staff of the control group received no training. A dental hygienist visited the living unit periodically to evaluate and provide feedback on the plaque index scores taken by the caregivers in both experimental groups. RESULTS: The plaque indexes of group I showed significant improvement over the control group and group II. CONCLUSION: The results of this pilot study support the other findings of higher plaque indexes for residents with mental retardation and that modifying toothbrushing policies and staff training are not as critical to the improvement of the clients' oral hygiene as is the presence of an involved, interested third party.

Adult↗
PubMed1999

Trading force for speed: why superfast crossbridge kinetics leads to superlow forces.

Superfast muscles power high-frequency motions such as sound production and visual tracking. As a class, these muscles also generate low forces. Using the toadfish swimbladder muscle, the fastest known vertebrate muscle, we examined the crossbridge kinetic rates responsible for high contraction rates and how these might affect force generation. Swimbladder fibers have evolved a 10-fold faster crossbridge detachment rate than fast-twitch locomotory fibers, but surprisingly the crossbridge attachment rate has remained unchanged. These kinetics result in very few crossbridges being attached during contraction of superfast fibers (only approximately 1/6 of that in locomotory fibers) and thus low force. This imbalance between attachment and detachment rates is likely to be a general mechanism that imposes a tradeoff of force for speed in all superfast fibers.

Adenosine Triphosphatases↗
PubMed1999

Nitric oxide donors, sodium nitroprusside and S-nitroso-N-acetylpencillamine, stimulate myoblast proliferation in vitro.

Nitric oxide (NO) is an inter- and intracellular messenger involved in a variety of physiologic and pathophysiologic conditions. The effect of two NO donors, sodium nitroprusside (SNP) and S-nitroso-N-acetylpenicillamine (SNAP) and their effect on myoblast proliferation was examined. Both donors stimulated an increase in myoblast cell number over a range (1-10 microM) of donor concentrations. However, 50 microM SNAP inhibited myoblast proliferation. Cell numbers from cultures treated with degraded 10 microM SNAP were equivalent to the control. Therefore, it appears NO can stimulate as well as inhibit myoblast proliferation.

Animals↗
PubMed1999

Seroprevalence of Helicobacter pylori, incidence of gastric cancer, and peptic ulcer-associated hospitalizations in a Canadian Indian population.

The living conditions of many aboriginal communities in Canada may place their residents at risk for H. pylori infection. Our aims were to determine: (1) the seroprevalence of H. pylori in a traditional Indian community, (2) the clinical relevance of H. pylori infection in this population, and (3) if H. pylori could be identified by polymerase chain reaction from the local water. A demographic questionnaire was administered, and blood was collected from subjects in an Indian community in northwestern Manitoba. The serum was analyzed by ELISA for IgG to H. pylori and to CagA. ABO and Lewis antigens were tested. Age-adjusted incidence of gastric cancer and of hospitalizations associated with diagnoses of peptic ulcer were determined for the Indian and non-Indian Manitoba population in the years 1989-1993. Nested PCR was performed on lake water using H. pylori-specific primers and the amplicons probed with an internal Dig-labeled probe. Three hundred six (59%) of approximately 518 individuals who were resident in the community at the time of the study were enrolled. The ELISA for H. pylori was positive in 291 (95%). There was no association between H. pylori seropositivity and age, sex, gastrointestinal complaints, medications, housing characteristics, and ABO or Lewis antigen status. CagA was positive in 84.5% of infected subjects. The average annual age-adjusted incidence of hospitalizations associated with diagnoses of peptic ulcer disease in Manitoba was higher for treaty-status Indians (394.3/100,000) than for non-Indians (203.8/100,000), but gastric cancer rates were similar (11.2/100,000 vs 11.6/100,000). No H. pylori DNA was detected in the lake water. In conclusion, the seroprevalence of CagA-positive H. pylori is high in this representative Manitoban Indian community. This may be associated with an increased risk for peptic ulcer disease but is not associated with an increased risk for gastric cancer.

Adolescent↗
PubMed1998

Expression of the mitotic motor protein Eg5 in postmitotic neurons: implications for neuronal development.

It is well established that the microtubules of the mitotic spindle are organized by a variety of motor proteins, and it appears that the same motors or closely related variants organize microtubules in the postmitotic neuron. Specifically, cytoplasmic dynein and the kinesin-related motor known as CHO1/MKLP1 are used within the mitotic spindle, and recent studies suggest that they are also essential for the establishment of the axonal and dendritic microtubule arrays of the neuron. Other motors are required to tightly regulate microtubule behaviors in the mitotic spindle, and it is attractive to speculate that these motors might also help to regulate microtubule behaviors in the neuron. Here we show that a homolog of the mitotic kinesin-related motor known as Eg5 continues to be expressed in rodent neurons well after their terminal mitotic division. In neurons, Eg5 is directly associated with the microtubule array and is enriched within the distal regions of developing processes. This distal enrichment is transient, and typically lost after a process has been clearly defined as an axon or a dendrite. Strong expression can resume later in development, and if so, the protein concentrates within newly forming sprouts at the distal tips of dendrites. We suggest that Eg5 generates forces that help to regulate microtubule behaviors within the distal tips of developing axons and dendrites.

Animals↗
PubMed1998

In vivo phosphocreatine and ATP in piglet cerebral gray and white matter during seizures.

The creatine kinase (CK) reaction is thought to be important in coupling ATP metabolism and regulating ADP concentration in tissues with high and variable ATP turnover, including cerebral gray matter (GM). There is low phosphocreatine (PCr), low CK reaction rates, and high mitochondrial CK (MiCK) isoenzyme activity in GM compared to white matter (WM). To compare the CK reaction in GM and WM when ATP metabolism is high, CK reactants and reaction rates were measured in predominantly GM and WM slices in vivo in 2 and 14-day old piglets during pentylenetetrazole (PTZ) seizures using 31P nuclear magnetic resonance (NMR) 1-dimensional chemical shift imaging (CSI). Arterial pressure, temperature, and blood gasses were stable at both ages. Before seizures, the PCr/nucleoside triphosphate (NTP) ratio was higher in WM than GM at both ages with a developmental increase seen in WM. The CK reaction rate constant increased in both regions between 2 and 14 days. During seizures, PCr/NTP increased in GM at 14 days due to increased PCr while the ratio and PCr decreased in WM. The NTP was more stable in WM and GM at both ages. The CK reaction rate decreased in both regions more at 2 than at 14 days. Thus, brain ATP, deduced from NTP, is stable during seizures in the piglet. In GM stable ATP is associated with a unique increase in PCR concentration.

Adenosine Triphosphate↗
PubMed1998

Effects of feeding Lunaria oil rich in nervonic and erucic acids on the fatty acid compositions of sphingomyelins from erythrocytes, liver, and brain of the quaking mouse mutant.

Feeding an oil from Lunaria biennis rich in 22:1n-9 and 24:1n-9 to homozygous quaking (qk.qk) mice caused a large increase in the percentage of 24:1n-9 and corresponding decreases in the percentage of 24:0 and 22:0 in sphingomyelins from liver, erythrocytes, and milk. Brain sphingomyelin from 2-wk-old qk.qk pups born to qk.qk mothers maintained on the Lunaria oil had essentially normal percentage of 24:1n-9 and 18:0, in contrast to pups born to mothers maintained on a control oil rich in 18:1n-9 whose brain sphingomyelin had a markedly reduced percentage of 24:1n-9 and an increased percentage of 18:0. After 2 wk and up to and beyond weaning, the qk.qk pups from Lunaria-fed mothers weaned on to the Lunaria diet had a markedly decreased percentage of 24:1n-9 in their brain sphingomyelin, accompanied by an increased percentage of 18:0, as compared to heterozygous quaking mice. However, the percentage of 24:1n-9 in brain sphingomyelin in qk.qk pups weaned on to the Lunaria diet continued throughout this period (2-8 wk postbirth) to be significantly higher than in qk.qk pups weaned on to the control diet. We conclude that dietary 24:1n-9 influences the fatty acid composition of brain sphingomyelin in qk.qk mice, but only via the mother in pre- or early postnatal animals. We further consider that the dietary effects may be elicited mainly in the sphingomyelin of nonmyelinated brain cells, and that the nervonic acid in myelin sphingomyelin may be formed mainly by chain elongation in oligodendrocytes from shorter chain fatty acid precursors.

Animal Nutritional Physiological Phenomena↗