PubMed Health⌕ Search

Biomedical subjects

B Cook

Publications and source records attributed to B Cook.

At least 55 records · Page 3Linked to original sources

Apoptotic photoreceptor degeneration in experimental retinal detachment.

PURPOSE: To investigate the possibility that cell death in retinal detachment may occur by reactivation of apoptotic programmed cell death mechanisms. METHODS: Unilateral retinal detachments were created in adult cats using 0.25% sodium hyaluronate; detached and control retinas were studied at different intervals. Internucleosomal DNA fragmentation (one of the landmarks of apoptosis) was investigated in tissue sections with the TUNEL technique, which uses terminal transferase to label with biotinylated nucleotides the 3' ends of DNA fragments. Sections also were labeled with propidium iodide, which intensely stains pyknotic nuclei. In addition, one time point was selected for analysis with electron microscopy. RESULTS: TUNEL-positive (T+) and propidium iodide-positive (PI+) cells almost never were observed in retinas from control eyes, but they were abundant at defined time points after retinal detachment, appearing almost exclusively in the photoreceptor layer. Their frequency was particularly high 1 to 3 days after detachment but declined rapidly over the next several weeks. T+ cells were still present 28 days after retinal detachment. Electron microscopy also revealed evidence of apoptotic cells after retinal detachment. CONCLUSIONS: Results are consistent with the hypothesis that photoreceptor degeneration after retinal detachment occurs through apoptosis, usually associated with intrinsic, programmed cell death mechanisms. The detection of a rapid wave of photoreceptor degeneration seems to suggest that early therapeutic interventions might be recommended; agents capable of interfering with the apoptotic mechanism could have a role in the prevention of cell losses that represent a critical complication of retinal detachment.

Animals↗

Cephalic pyoderma gangrenosum (PG)-like lesions as a presenting sign of Wegener's granulomatosis.

BACKGROUND: Pyoderma gangrenosum (PG)-like lesions can be associated with Wegener's granulomatosis (WG); in rare instances, they could be the presenting sign of WG. The purpose of this study was to elucidate the relationship between these two disorders. METHODS: The clinical and histologic data from a case of WG with primary ulcerative lesions of the face were compared with five other cases previously reported in the literature. RESULTS: A predominance among young men was noted. In three patients the histology of the skin ulcerations was suggestive of WG, in the remaining three, including the case described, it was nonspecific. Two cases developed pulmonary WG after the skin lesions cleared, showing that the extent and severity of skin lesions do not necessarily correlate with the systemic disease. CONCLUSIONS: When the histology of the skin is nonspecific, the diagnosis of PG or PG-like lesions of the head and neck should not be considered definitive and the patients should be carefully monitored to rule out the possible presence of WG.

Adolescent↗

The reliability of urinary 5-HIAA levels.

Examination of the serotonin metabolite, 5-hydroxyindoleacetic acid (5-HIAA), in the urine of psychiatry patients has generally not been used because the reliability of urinary 5-HIAA levels has been questioned. Thirty-seven generalized anxiety disordered patients collected two consecutive urines for measurement of 5-HIAA. The correlation of the 5-HIAA collections was r = 0.82, p = 0.0001.

Adult↗

A comparison of the redistribution and reinjection techniques in dipyridamole thallium tomography.

The effect of the injection of additional thallium after a redistribution study and prior to a further resting study was evaluated in 21 patients with angiographically proven coronary artery disease. Using dipyridamole as the stress mechanism, the studies were carried out tomographically and the results analysed quantitatively with the Bull's-eye technique. Two patients had normal scans. Of the remaining 19, 11 patients had a perfusion defect which appeared irreversible on redistribution imaging. However, six of these patients demonstrated improved or normal uptake after the second injection of thallium. Of the eight patients with a reversible defect, two revealed considerably greater reversibility after reinjection. These results indicate that the reinjection of thallium prior to the resting study significantly (P < 0.02) improves the detection rate of ischaemia during dipyridamole thallium tomography.

Coronary Disease↗

Alcoholism in manic depressive (bipolar) patients.

Bipolar patients with alcoholism were compared to nonalcoholic bipolar patients on clinical and family history variables. All patients were systematically examined using a structured interview. There was no increase in the family history of alcoholism in the alcoholic/bipolar. This argues against separate transmission of alcoholism and bipolar illness in bipolar patients who meet diagnostic criteria for both bipolar illness and alcoholism. The possibility remains that alcoholism is secondary to the bipolar illness in some cases. Likewise, there is a possibility that preexisting alcoholism may, by a sequence of events, produce an induced "organic" bipolar picture.

Adult↗

Impact of the diagnostic procedure on outcome measures of swallowing rehabilitation in head and neck cancer patients.

This study was designed to determine whether swallow rehabilitation outcomes were affected by the type of evaluation procedure utilized by the clinician. The two evaluation techniques compared were the bedside examination and videofluoroscopy (the modified barium swallow). Ten institutions participated in this study, enrolling a total of 103 partial laryngectomized patients, 21 in the bedside arm and 82 in the videofluoroscopy arm. Data on recovery of oral intake were collected weekly. All patients received an X-ray study of swallow at 3 months after the operation. Mean time to oral intake of food was significantly lower in patients assessed with bedside examination. Overall swallow measures of transit times and swallow efficiencies after 3 months revealed significantly better function in the videofluoroscopy group. Results are discussed in terms of the visibility of swallow physiology with the two assessment techniques, the accuracy of therapy planning with the bedside examination versus videofluoroscopy and the ability of head and neck cancer patients to tolerate some aspiration without developing aspiration pneumonia.

Deglutition↗

The effect of atenolol on dipyridamole 201Tl myocardial perfusion tomography in patients with coronary artery disease.

The effect of atenolol on dipyridamole 201Tl myocardial perfusion tomography was evaluated in 12 patients with angiographically proven coronary artery disease. The patients had dipyridamole 201Tl tomography performed after 7 days treatment with 50 mg atenolol and then repeated after a further 7 days treatment with placebo. The images were interpreted qualitatively by two experienced observers and quantitatively using the Bullseye technique. Qualitative analysis of the images revealed that four of the 12 patients had larger defects on their scans whilst receiving atenolol compared to placebo. The remaining eight patients had defects which were the same size on both treatments. The severity of defects assessed qualitatively was not significantly influenced by atenolol therapy (P = 0.13, McNemera's test). The results obtained with the Bullseye method did not demonstrate significant statistical differences for defect size, degree of reversibility or percentage reversibility whilst the patients were receiving atenolol or placebo (Wilcoxon Rank Sum Test). Atenolol increased the size of perfusion defects on dipyridamole 201Tl tomography qualitatively and quantitatively for four patients in this group of 12 with proven coronary artery disease. Although this did not achieve a high level of statistical significance physicians should be aware that atenolol can influence the images obtained at dipyridamole 201Tl tomography.

Adult↗

Gallium-67 scans as an adjunct to computed tomography scans for the assessment of a residual mediastinal mass in pediatric patients with Hodgkin's disease. A Pediatric Oncology Group study.

This study determines the utility of gallium-67 (Ga-67) scintigraphs as an adjunct to computed tomography (CT) scans for the assessment of residual mediastinal masses in children and adolescents with advanced-stage Hodgkin's disease. At diagnosis 42 patients with CT scan-documented mediastinal disease had a Ga-67 scan performed. Thirty-four of 42 patients (81%) had gallium-avid mediastinal lesions, whereas in eight (19%), the Ga-67 scan was negative. At the completion of eight cycles of therapy of Mustargen (mechlorethamine), Oncovin (vincristine), procarbazine, prednisone (MOPP) alternating with doxorubicin, bleomycin, vinblastine, dacarbazine (ABVD), 21 of 34 patients with initially positive Ga-67 scans had them repeated; 18 of 21 converted to negative results, and three remained positive. In 11 of 18 patients, the loss of gallium avidity was consistent with a negative mediastinal CT scan. In seven, although the gallium scan was negative, the CT scan remained positive; all seven patients had a mediastinal biopsy of suspected residual disease and in all seven the biopsy results were negative for Hodgkin's disease. These preliminary results in a small cohort of patients demonstrate that Ga-67 scans may be of benefit in evaluating residual mediastinal masses in patients with Hodgkin's disease.

Adolescent↗

Review of neonatal screening programme for phenylketonuria.

OBJECTIVE: To review the neonatal screening programme during 1984-8. DESIGN: Analysis of data from screening laboratories and paediatricians. SUBJECTS: All live births in United Kingdom. MAIN OUTCOME MEASURES: Structure of programme; number of infants tested and number with phenylketonuria; number of infants missed; ages at testing and treatment. RESULTS: The proportion of infants tested approached 100%. The incidence of phenylketonuria was 11.7/100,000 births (445 subjects): 273 had classic phenylketonuria and three had defects of cofactor metabolism. One child with phenylketonuria was known to have been missed compared with three in 1979-83 and six in 1974-8. Seven subjects had been missed over the 15 years due to negative test results. All seven had been tested with the bacterial inhibition assay, although only 53% of infants had been so tested; the difference between the expected and observed proportion was significant (Fisher's exact test, p = 0.017). Eleven infants with classic phenylketonuria were not tested by 14 days of age and 23 (8%) did not start treatment until after 20 days, an improvement compared with 36 (15%) in 1979-83. There were, however, wide regional variations (0% to 27% treated after 20 days). CONCLUSION: The screening programme achieves high coverage and effectiveness, although some children are still missed. A national practice for screening may help reduce regional variations.

Age Factors↗

Controlled discontinuation of benzodiazepine treatment for patients with panic disorder.

OBJECTIVE: The purpose of this study was to compare the effects of discontinuing treatment with intermediate- and long-acting benzodiazepines. METHOD: Fifty patients with panic disorder who had taken part in a double-blind treatment study and had responded to alprazolam, diazepam, or placebo for 8 months were asked to stop taking these medications gradually. RESULTS: After a relatively rapid dose reduction, the majority of patients relapsed. Rebound anxiety and withdrawal symptoms were identified in a substantial minority of patients. Those who were taking alprazolam showed earlier and more intense rebound anxiety and withdrawal symptoms than did the patients who received diazepam. Both the level of pretreatment anxiety and the drug the patient was taking predicted the level of anxiety when drug treatment was discontinued. CONCLUSIONS: The findings indicate that withdrawal phenomena commonly occur after patients stop taking benzodiazepines and that they are more frequent after discontinuation of treatment with shorter-acting drugs.

Adult↗

A review of the role of established tumour markers.

Increasing numbers of commercial assays for the established tumour markers are available which are capable of excellent analytical performance. Whilst all these assays are useful as research tools, their clinical value is more limited and should be appreciated before any decision is taken to offer a tumour marker assay service. 1. Calcitonin (medullary carcinoma of thyroid), alphafetoprotein (hepatoma) and human chorionic gonadotrophin (choriocarcinoma) are the only tumour markers that can be used for screening for malignancy in high risk populations. 2. Hormones, paraproteins, alphafetoprotein, human chorionic gonadotrophin and prostate specific antigen are valuable in establishing the diagnosis of certain tumour types. 3. Alphafetoprotein and human chorionic gonadotrophin concentrations at the time of diagnosis are of value in predicting prognosis in specific tumour types. 4. Although their sensitivity for a particular tumour type may be poor, most tumour markers can be used for monitoring the therapy and follow-up of selected marker positive patients. Optimal clinical results of the management of patients with malignancy are usually obtained by specialist centres, and laboratory tumour marker services should be established so that they are appropriate to local oncology specialities.

Biomarkers, Tumor↗

Assessment of risk from exposure to acrylonitrile: the general approach used by a consultant.

The concern from low-level exposure to acrylonitrile is primarily due to its potential for carcinogenicity. Several epidemiology studies provide suggestive evidence for an association of lung cancer in workers exposed to acrylonitrile; however, smoking may be a contributing factor and therefore the role of acrylonitrile as a causative factor is unclear. Seven animal bioassays, using three routes of exposure and two strains of rats, have provided consistent results. Tumors were induced in all studies, with the primary sites of tumor induction being the brain, ear canal, gastrointestinal tract and mammary glands. The linearized multistage model was used for extrapolation purposes. The risk based on brain tumors (astrocytomas) and stomach tumors following oral exposures ranged from 1 x 10(-1) to 4 x 10(-1)mg-1kg-1day-1. The risk of inhalation exposure is somewhat less, (2-3) x 10(-2). Support for carcinogenic potential is obtained from mutagenicity studies. Acrylonitrile has been found to be mutagenic and also binds with DNA. It has been speculated that acrylonitrile is metabolized to 2-cyanoethylene oxide, which is the proximate carcinogen.

Acrylonitrile↗

Comparison of panic disordered patients with high versus low MHPG.

Fourteen panic disorder patients with low 3-methoxy-4-hydroxyphenylglycol (MHPG) were compared to 14 patients with high MHPG. Patients with low MHPG were more likely during the preceding month to have experienced spontaneous panic attacks (P less than 0.008) than were patients with high MHPG. Patients with high MHPG had increased severity ratings on several individual symptoms of anxiety.

Adult↗

Elevated levels of N-acetyl-beta-glucosaminidase in affective disorders and chemical dependence.

Levels of N-acetyl-beta-glucosaminidase (NAG) were examined in 575 patients with various psychiatric diagnoses and 38 non-ill controls. Ten percent of affectively disordered patients and 19% of chemically dependent patients had abnormal NAG levels, whereas none of the 38 controls did (P less than 0.05 and P less than 0.003 respectively). Other psychiatric diagnostic groups were not associated with abnormal levels of this enzyme.

Acetylglucosaminidase↗