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Biomedical subjects

J Collins

Publications and source records attributed to J Collins.

At least 91 records · Page 5Linked to original sources
PubMed2000

Subarachnoid drainage of an established or chronic pseudomeningocele.

Incidental dural tears are a common complication of lumbar spine surgery, but if unrecognized cerebrospinal fluid (CSF) leakage can lead to the formation of a fistula or pseudomeningocele. Traditionally, fistulae and pseudomeningoceles have been treated with open revision surgery, but acute fistulae with direct CSF leakage through the incision site have reportedly been treated by extracorporal drainage. This report presents a case in which an established or chronic pseudomeningocele was successfully managed without open surgical repair.

Adult↗
PubMed2000

Chest wall trauma.

Sufficient trauma to the chest can result in injury to the bony thorax and soft tissues of the chest wall, increasing patient morbidity and mortality. Fractured ribs can lacerate the pleura, lung, or abdominal organs. Fractures to upper ribs, clavicle, and upper sternum can signal brachial plexus or vascular injury. Paradoxical movement of a flail chest can impair respiratory mechanics, promote atelectasis, and impair pulmonary drainage. Most patients with thoracic spine fracture-dislocations have complete neurologic deficits. Scapular fractures, associated with other injuries in almost all patients, are frequently overlooked on supine chest radiographs. Sternal fractures, associated with clinically silent myocardial contusion, are best visualized on chest computed tomography (CT). Severe trauma to the chest wall can be associated with large chest wall hematomas or collections of air within the chest wall that can communicate with the intrathoracic space. CT scanning can easily distinguish chest wall from parenchymal or mediastinal injury, whereas this differentiation my not be possible with chest radiography.

Diagnosis, Differential↗
PubMed2000

Early start of adjuvant chemotherapy may improve treatment outcome for premenopausal breast cancer patients with tumors not expressing estrogen receptors. The International Breast Cancer Study Group.

PURPOSE: The proper time to commence adjuvant chemotherapy after primary surgery for breast cancer is unknown. An analysis of the International (Ludwig) Breast Cancer Study Group (IBCSG) Trial V at a median follow-up of 11 years suggested that early initiation of adjuvant chemotherapy might improve outcome for premenopausal, node-positive patients whose tumors did not express any estrogen receptor (ER). PATIENTS AND METHODS: We investigated the relationship between early initiation of adjuvant chemotherapy, ER status, and prognosis in 1,788 premenopausal, node-positive patients treated on IBCSG trials I, II, and VI. The disease-free survival for 599 patients (84 with ER-absent tumors) who commenced adjuvant chemotherapy within 20 days (early initiation) was compared with the disease-free survival for 1,189 patients (142 with ER-absent tumors) who started chemotherapy 21 to 86 days after surgery (conventional initiation). The median follow-up was 7.7 years. RESULTS: Among patients with ER-absent tumors, the 10-year disease-free survival was 60% for the early initiation group compared with 34% for the conventional initiation group (226 patients; hazard ratio [HR], 0. 49; 95% confidence interval [CI], 0.33 to 0.72; P =.0003). This difference remained statistically significant in a Cox multiple regression analysis controlling for study group, number of positive nodes, tumor size, age, vessel invasion, and institution (HR, 0.60; 95% CI, 0.39 to 0.92; P =.019). Conversely, early initiation of chemotherapy did not significantly improve disease-free survival for patients with tumors expressing ER (1,562 patients; multiple regression HR, 0.93; 95% CI, 0.79 to 1.10; P =.40). CONCLUSION: In premenopausal patients with ER-absent tumors, early initiation of systemic chemotherapy after primary surgery might improve outcome. Further confirmatory studies are required before any widespread modification of current clinical practice. In premenopausal patients with tumors expressing some ER, gains from early initiation are unlikely to be clinically significant.

Adult↗
PubMed2000

Burdens and benefits of adjuvant cyclophosphamide, methotrexate, and fluorouracil and tamoxifen for elderly patients with breast cancer: the International Breast Cancer Study Group Trial VII.

PURPOSE: Information on the tolerability and efficacy of adjuvant chemoendocrine therapy for older women is limited. We studied these issues using the data collected as part of the International Breast Cancer Study Group Trial VII. PATIENTS AND METHODS: Postmenopausal women with operable, node-positive breast cancer were randomized to receive either tamoxifen alone for 5 years (306 patients) or tamoxifen plus three consecutive cycles of classical cyclophosphamide (100 mg/m(2) orally days 1 to 14), methotrexate (40 mg/m(2) intravenous days 1 and 8), and fluorouracil (600 mg/m(2) intravenous days 1 and 8) every 28 days (CMF; 302 patients). The median follow-up was 8.0 years. RESULTS: Among the 299 patients who received at least one dose of CMF, women 65 years of age or older (n = 76) had higher grades of toxicity compared with women less than 65 years old (n = 223) (P =.004). More women in the older age group compared with the younger women experienced grade 3 toxicity of any type (17% v 7%, respectively), grade 3 hematologic toxicity (9% v 5%, respectively), and grade 3 mucosal toxicity (4% v 1%, respectively). Older patients also received less than their expected CMF dose compared with younger postmenopausal women (P =.0008). The subjective burdens of treatment, however, were similar for younger and older patients based on quality-of-life measures (performance status, coping, physical well-being, mood, and appetite). For older patients, the 5-year disease-free survival (DFS) rates were 63% for CMF plus tamoxifen and 61% for tamoxifen alone (hazards ratio [HR], 1.00; 95% confidence interval [CI], 0.65 to 1.52; P =.99). For younger patients, the corresponding 5-year DFS rates were 61% and 53% (HR, 0.70; 95% CI, 0.53 to 0.91; P =.008), but the test for heterogeneity of CMF effect according to age group was not statistically significant. The reduced effectiveness of CMF among older women could not be attributed to dose reductions according to dose received. CONCLUSION: CMF tolerability and effectiveness were both reduced for older patients compared with younger postmenopausal node-positive breast cancer patients who received tamoxifen for 5 years. The development and evaluation of less toxic and more effective chemotherapy regimens are required for high-risk elderly patients.

Age Factors↗
PubMed2000

CT findings of pneumonia after lung transplantation.

OBJECTIVE: The purpose of this study was to describe the CT findings of pneumonia in patients who had undergone lung transplantation and to determine if specific imaging features existed for the different infectious organisms. MATERIALS AND METHODS: The authors retrospectively reviewed the medical records of 262 patients with transplanted lungs at two lung transplantation centers. Patients with a documented pneumonia and correlating abnormal findings on CT (39 patients with 45 pneumonias) were included in the study. RESULTS. Of 45 pneumonias, Cytomegalovirus (n = 15), Pseudomonas (n = 7), and Aspergillus (n = 8) organisms were the most common single responsible infectious agents. The most common CT findings of pneumonia consisted of consolidation (n = 37; 82%), ground-glass opacification (n = 34; 76%), septal thickening (n = 33; 73%), pleural effusion (n = 33; 73%), and multiple (n = 25; 56%) or single (n = 2; 4%) nodules. No significant difference in the prevalence of findings was revealed among bacterial, viral, and fungal pneumonias (p >.05, chisquare test). Of 25 pneumonias in patients with a single transplanted lung, parenchymal abnormalities involved both lungs in 12 (48%), only the transplanted lung in 11 (44%), and only the native lung in two (8%). CONCLUSION: The manifestations revealed on CT of bacterial, viral, and fungal pneumonia after lung transplantation are similar, consisting of a combination of consolidation, ground-glass opacification, septal thickening, pleural effusion, or multiple nodules. Therefore, these findings cannot be used to suggest the infectious organisms in this patient population.

Adolescent↗
PubMed2000

A decade of aerobic endurance training: histological evidence for fibre type transformation.

BACKGROUND: Researchers employing a variety of training methods have demonstrated a fast-to-slow fibre transformation in animal skeletal muscle. The observation as to whether this occurs in exercise trained humans is limited and equivocal. METHODS EXPERIMENTAL DESIGN: to examine this issue, skeletal muscle from seven subjects who had participated in a decade or more of high intensity aerobic training (DT) and six nontrained (NT) subjects was obtained by muscle biopsy from the vastus lateralis muscle (VL) and subjected to a modified myofibrillar ATPase technique to identify muscle fibre types. Muscle tissue was histochemically treated by exposure to an alkaline preincubation (pH 9.9), an acid preincubation (pH 4.3 or 4.6) and the formate-KCI preincubation buffer (pH 4.54), previously employed in animal studies. RESULTS: The formate-KCl preincubation medium identified all major fibre types at a single pH in human subjects. The percentage of type I fibres in DT was 70.9% vs 37.7% in NT (p<0.01), while the type IIa fibres in DT (25.3%) was much lower (p<0.01) than NT (51.8%). Surprisingly, type IIa fibres in the DT group displayed lesser oxidative staining intensity (p<0.01) than type IIa fibres from the NT group. Mean cross-sectional area of type I fibres for DT (6233.9+/-1421.7 microm2) was greater (p<0.05) than either type I (5746.8+/-1135.2 microm2) or II (5693.5+/-1214.6 microm2) from NT. CONCLUSIONS: The results revealed that endurance training may promote a transition from type II to type I muscle fibre types and occurs at the expense of the type II fibre population.

Adenosine Triphosphatases↗
PubMed2000

Peroxidation of proteins and lipids in suspensions of liposomes, in blood serum, and in mouse myeloma cells.

There is growing evidence that proteins are early targets of reactive oxygen species, and that the altered proteins can in turn damage other biomolecules. In this study, we measured the effects of proteins on the oxidation of liposome phospholipid membranes, and the formation of protein hydroperoxides in serum and in cultured cells exposed to radiation-generated hydroxyl free radicals. Lysozyme, which did not affect liposome stability, gave 50% protection when present at 0.3 mg/ml, and virtually completely prevented lipid oxidation at 10 mg/ml. When human blood serum was irradiated, lipids were oxidized only after the destruction of ascorbate. In contrast, peroxidation of proteins proceeded immediately. Protein hydroperoxides were also generated without a lag period in hybrid mouse myeloma cells, while at the same time no lipid peroxides formed. These results are consistent with the theory that, under physiological conditions, lipid membranes are likely to be effectively protected from randomly-generated hydroxyl radicals by proteins, and that protein peroxyl radicals and hydroperoxides may constitute an important hazard to biological systems under oxidative stress.

Animals↗
PubMed1999

Determination of iron in solutions with the ferric-xylenol orange complex.

Formation of a colored complex between ferric iron and xylenol orange has been used in a variety of applications, but there is disagreement about the number of complexes that exist, their stoichiometry, pH dependence, solvent effects, and other parameters. In this study we investigated the use of the complex to measure micromolar concentrations of iron in aqueous and alcohol solutions. The results show that the optimum wavelength for the measurement is 560 nm, that only a 1:1 ferric:xylenol orange complex forms, and that its molar absorption coefficient is affected by the solvent, the source of the xylenol orange, and the pH. Under the recommended conditions, formation of the complex is completed in less than 5 min and it is stable in several solvents. Its molar absorption coefficient in 25 mM H(2)SO(4) is 20,100 or 14,500 M(-1) cm(-1), depending on the source of the dye. A recommended protocol for the use of the assay is given.

Chemistry Techniques, Analytical↗
PubMed1999

Hydroperoxide assay with the ferric-xylenol orange complex.

A range of hydroperoxides were reduced by ferrous ions in acid solutions and the amount of ferric product was measured as a xylenol orange complex at 560 nm. Dilute sulfuric acid, 50% acetic acid, and acidified 90% methanol proved to be suitable solvents. The color developed within 15 min and was stable for several hours in most solvents. The apparent molar absorption coefficients (epsilon(app)) of H(2)O(2) and of the t-butyl, cumene, bovine serum albumin, and linoleate hydroperoxides were measured, using known hydroperoxide concentrations determined independently by an iodometric assay. The epsilon(app) values differed significantly and depended on the hydroperoxide, the solvent, and the source of the xylenol orange. The numbers of Fe(3+) ions formed by a range of hydroperoxides in different solvents showed that H(2)O(2) gave 2.5, t-butyl and cumene hydroperoxides 5, and the other hydroperoxides 2 Fe(3+) ions per -OOH group. This general finding allows the determination of approximate hydroperoxide concentrations even in chemically complex systems. Accurate measurements require knowledge of the nature of the hydroperoxide and its epsilon(app) and careful control of the assay conditions. However, the convenience of the assay makes it potentially useful in a variety of applications.

Animals↗
PubMed1999

The human LARGE gene from 22q12.3-q13.1 is a new, distinct member of the glycosyltransferase gene family.

Meningioma, a tumor of the meninges covering the central nervous system, shows frequent loss of material from human chromosome 22. Homozygous and heterozygous deletions in meningiomas defined a candidate region of >1 Mbp in 22q12.3-q13.1 and directed us to gene cloning in this segment. We characterized a new member of the N-acetylglucosaminyltransferase gene family, the LARGE gene. It occupies >664 kilobases and is one of the largest human genes. The predicted 756-aa N-acetylglucosaminyltransferase encoded by LARGE displays features that are absent in other glycosyltransferases. The human like-acetylglucosaminyltransferase polypeptide is much longer and contains putative coiled-coil domains. We characterized the mouse LARGE ortholog, which encodes a protein 97.75% identical with the human counterpart. Both genes reveal ubiquitous expression as assessed by Northern blot analysis and in situ histochemistry. Chromosomal mapping of the mouse gene reveals that mouse chromosome 8C1 corresponds to human 22q12.3-q13.1. Abnormal glycosylation of proteins and glycosphingolipids has been shown as a mechanism behind an increased potential of tumor formation and/or progression. Human tumors overexpress ganglioside GD3 (NeuAcalpha2,8NeuAcalpha2, 3Galbeta1,4Glc-Cer), which in meningiomas correlates with deletions on chromosome 22. It is the first time that a glycosyltransferase gene is involved in tumor-specific genomic rearrangements. An abnormal function of the human like-acetylglucosaminyltransferase protein may be linked to the development/progression of meningioma by altering the composition of gangliosides and/or by effect(s) on other glycosylated molecules in tumor cells.

Amino Acid Sequence↗