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Biomedical subjects

M Stevens

Publications and source records attributed to M Stevens.

At least 145 records · Page 8Linked to original sources
PubMed1990

A controlled trial of colchicine to reduce the elastase load in the lungs of cigarette smokers with chronic obstructive pulmonary disease.

Current data suggest that emphysema in smokers is caused at least in part by the unrestrained action of neutrophil elastase on pulmonary tissues. Since colchicine reduces the secretion of enzymes from stimulated neutrophils, we designed a clinical trial to determine if colchicine could reduce the elastase load in the lungs or several putative indicators of elastin destruction. We carried out a prospective, double-blind, randomized, and placebo-controlled clinical trial. Outpatients seeking treatment for chronic obstructive pulmonary disease at the University of Texas Health Center at Tyler who met specific criteria were recruited into the study. A group of 46 cigarette smokers between 45 and 75 yr of age with chronic obstructive pulmonary disease (COPD) were studied. Colchicine or placebo was given orally in disguised capsules, 0.6 mg three times per day. Volunteers were placed on a baseline bronchodilator regimen of Theodur orally and albuterol by inhalation. Blood, urine, and bronchoalveolar lavage fluids were obtained after 1 wk of stabilization. The patients were then randomized and treated for 14 days with colchicine, and the measurements were repeated. Modifications in plasma elastin peptides and neutrophil elastase-generated fibrinopeptide A, urinary desmosines, and bronchoalveolar lavage fluid neutrophils or neutrophil elastase were the indicators of success or failure of the treatment. Pre- and posttreatment measurements in each patient and the difference between colchicine-treated and placebo-treated groups were compared. There were no statistically significant differences in either of the two types of analyses in any of the variables. We conclude that variables related to elastase load in the lungs were not modified by colchicine treatment. If a drug can be identified that is successful in modifying one of these variables, it would then have to be tested in a large-scale clinical trial in which the rate of decline in the FEV1.0 or mortality would be measured. The data presented here may provide useful information about the variability of key measurements of elastase load in the lungs and the breakdown of elastin and may aid investigators in designing similar trials in the future.

Aged↗
PubMed1989

Normal or early development of puberty despite gonadal damage in children treated for acute lymphoblastic leukemia.

To determine the timing of pubertal development and the frequency of gonadal dysfunction in children who survive acute lymphoblastic leukemia, we assessed pubertal status and the plasma levels of sex steroids, gonadotropin, and inhibin in 45 children (20 girls and 25 boys) who had received combination chemotherapy along with 24 Gy of irradiation to the cranium (modified LSA2L2 protocol). We also reexamined testicular biopsy specimens, obtained at the time of the cessation of chemotherapy, for the presence of germ cells. Germ-cell damage, indicated by marked elevations in the plasma level of follicle-stimulating hormone (P less than 0.001 for the comparison with normal children), was evident in both sexes and was confirmed in the boys by the absence of germ cells in the testicular biopsy specimens and by the small size of the testes for pubic-hair stage. Only 44 percent of the pubertal girls had measurable plasma inhibin levels, as compared with more than 93 percent of normal pubertal girls. Although plasma sex-steroid levels were normal, the secretion of luteinizing hormone in response to stimulation with gonadotropin-releasing hormone was elevated in the pubertal children (P less than 0.01 for the comparison with normal controls)--a finding that suggests compensation for decreased gonadal function. Despite clear evidence of gonadal damage, girls had early menarche at a mean age (+/- SD) of 11.95 +/- 0.91 years, as compared with the Australian standard of 12.98 +/- 1.11 years (P less than 0.01). Thus, in girls, puberty was early despite primary gonadal damage. Thirteen of 23 boys reached puberty at a mean age of 12.36 +/- 0.73 years. We conclude that treatment for acute lymphoblastic leukemia may lead to primary gonadal damage in both sexes, regardless of the age at treatment, but that the secondary characteristics of puberty develop at a normal age or, in girls, relatively early.

Adolescent↗
PubMed1989

High- and low-affinity receptors for murine interleukin 6. Distinct distribution on B and T cells.

The distribution of the murine receptor for interleukin (IL) 6 was examined on a variety of cells. Binding sites for IL 6 were found on many cell lines including fibroblasts and bone marrow-derived macrophages. The highest density of binding sites was found on B cell hybridomas and plasmacytomas, irrespective of their IL 6 dependence for growth. Scatchard analysis carried out with these cells identified about 1000 high-affinity sites (Kd = 25 pM) and 10,000 low-affinity sites (Kd = 2.5 nM). The binding was specific for IL 6 and led to the internalization of the ligand. Receptors for IL 6 were also present on other B cell lines, but binding on normal resting or activated B cells was below the limit of detection (less than 3 molecules/cell). In contrast, receptors were found on mature thymocytes and on peripheral T cells. However, unlike plasmacytomas and hybridomas, T cells expressed only high-affinity binding sites. The difference in the relative numbers of high- and low-affinity receptors on different cells suggests that IL 6 interacts with several proteins, the expression of which varies from one cell type to another.

Animals↗
PubMed1989

Long-term follow-up after unilateral nephrectomy and radiotherapy for Wilms' tumour.

Twenty-nine patients who had had unilateral nephrectomy for Wilms' tumour in one hospital were known to have survived more than 12 years. Sixteen agreed to attend for clinical review, of whom 14 had estimation of serum creatinine, 24-h urine protein excretion and endogenous creatinine clearance. The follow-up period was 13-26 years (median 17 years). All but one had had radiotherapy and all had chemotherapy (actinomycin D, 16; vincristine, 5). Some degree of kyphoscoliosis was present in all except the patient who did not receive radiotherapy. Four patients had diastolic blood pressure 90 mmHg or greater. Two patients had mild proteinuria (392, 361 mg/day). Serum creatinine ranged from 53 to 125 mumol/l and endogenous creatinine clearance ranged from 39 to 173 ml/min (median 81, mean 89). Of the 7 patients who were 20-26 years post-nephrectomy, 2 were hypertensive and 1 had elevated urinary protein excretion. We conclude that the long-term prognosis of unilateral nephrectomy in childhood is good.

Adolescent↗
PubMed1989

Comparative evaluation of a latex test for the identification of Staphylococcus aureus.

A rapid latex agglutination test, Staphaurex, was tested for its ability to identify Staphylococcus aureus using 72 reference strains and 785 clinical isolates of the family Micrococcaceae. All reference strains of Staphylococcus aureus were Staphaurex-positive. Non-Staphylococcus aureus reference strains were negative. Using clinical strains, the results of the Staphaurex test were compared with the results of other tests commonly used to identify Staphylococcus aureus. A total of 393 clinical isolates were classified as Staphylococcus aureus. The Staphaurex, slide coagulase, tube coagulase/human plasma and tube coagulase/rabbit plasma tests correctly identified 98%, 93.6%, 93.6% and 97.5% of the Staphylococcus aureus strains, respectively. The performance of the Staphaurex test, in terms of sensitivity and specificity, was significantly better than the slide coagulase test. It was as sensitive and almost as specific as the tube coagulase rabbit test and more sensitive than the tube coagulase human test.

Evaluation Studies as Topic↗
PubMed1989

Primary rib tumours in children (report of 27 cases with short literature review).

27 cases of primary malignant and benign rib tumours are reported. The most common malignant rib tumour in childhood is Ewing sarcoma (20 cases). Some other rare bone tumours and tumorous conditions (reticulosarcoma, aneurysmal bone cyst, monostotic rib eosinophilic granuloma, osteoid osteoma and lymphangioma) are also described. In the authors' opinion Ewing sarcoma presents with characteristic clinico-radiographic findings in most of the cases. Other monostotic, primary rib tumours and tumorous conditions in childhood--with the exception of exchondroma and enchondroma--rarely show diagnostic radiographic features.

Adolescent↗
PubMed1989

Primary bone tumours of the pelvis in childhood--Ewing's sarcoma of the ilium, pubis and ischium (report of 30 cases). (Part I).

30 children with Ewing's sarcoma, the most common malignant pelvic tumour in childhood, were analysed. The diagnosis of Ewing's sarcoma is relatively easy and can be established in most of the cases on plain radiography. The diagnostic radiographic features of the tumour are discussed. The two most important conditions in differential diagnosis are eosinophilic granuloma and the rare primary bone lymphoma. Osteomyelitis should rarely cause confusion unless the clinico-radiographic findings are not properly evaluated.

Bone Neoplasms↗
PubMed1989

Rare, primary iliac, pubic and ischial tumours in children (report of 14 cases)--Part II.

14 cases of rare, primary iliac, pubic and ischial bone tumours or tumorous conditions are reported. These include aneurysmal bone cyst, eosinophilic granuloma, cavernous haemangioma, osteoid osteoma, fibrous dysplasia, fibrous dysplasia with sarcomatous degeneration, chondrosarcoma, lymphoma and atypical malignant histiocytosis. The possibilities to be considered in the accurate radiographic recognition of primary tumours of iliac, pelvic and ischial bones are discussed.

Bone Cysts↗
PubMed1989

Construction of a database to identify Staphylococcus species.

A database was constructed for the routine identification of Staphylococcus species, isolated from man. The method comprised 15 conventional characterisation tests using substrates incorporated into agar plates and a multipoint inoculation system. The database was constructed from results of 125 reference strains and 1567 clinical isolates. In an evaluation trial, using a probability profile index generated from the database, 529 of 559 (94.6%) further clinical isolates were identified to species level. A further 20 (3.6%) gave low discrimination between two species. The proposed scheme was rapid, reliable, and inexpensive.

Bacteriological Techniques↗
PubMed1989

Coping strategies of hospitalized adolescents.

This study identified how adolescents cope with hospitalization for surgery and the congruency between anticipated and actual coping strategies. Preoperative emotional state was examined in relation to the type of reported coping strategies. Fifty-nine adolescents were interviewed before and after surgery. Six coping strategies were identified. Although there was no statistically significant relationship between anticipated and actual strategies, the highest proportion of adolescents in the study (23 of 59) both anticipated and reported the use of strategies to regulate the emotional distress aroused by stressful encounters during hospitalization. No statistically significant relationship existed between preoperative emotional state and reported coping strategies.

Adaptation, Psychological↗
PubMed1989

Histologic evaluation of new attachment apparatus formation in humans. Part I.

Part I of this three-part human study evaluated the formation of a new attachment apparatus (bone, cementum, and periodontal ligament) on pathologically exposed root surfaces in an open and closed environment. The most apical level of calculus on the root served as a histologic reference point to measure regeneration on root surfaces exposed to the oral environment. Attempts were made to initiate the formation of a new attachment apparatus by flap curettage, root planing, coronectomy, and submersion of vital roots beneath the mucosa. Nonsubmerged defects were treated by the same surgical technique and served as controls. Biopsies were obtained at 6 months and regeneration was evaluated histometrically by two investigators who were unaware of the treatment performed. Data from 9 patients with 25 submerged and 22 nonsubmerged defects were submitted for statistical analysis. Results indicate that a new attachment apparatus did not form in any of the 22 nonsubmerged teeth; a new attachment apparatus did form in a submerged environment (0.75 mm); significantly more new attachment apparatus (P less than 0.05), new cementum (P less than 0.01), new connective tissue (P less than 0.05), and new bone (P less than 0.02) formed in submerged defects; new cementum was cellular in nature and formed equally well on old cementum and dentin. Greater percent positive regeneration of the attachment apparatus and all component tissues occurred in submerged defects and no extensive root resorption, ankylosis, or pulp death was observed on submerged or nonsubmerged roots.

Analysis of Variance↗
PubMed1989

Histologic evaluation of new attachment apparatus formation in humans. Part II.

There is conflicting evidence regarding the value of graft materials in enhancing the formation of new bone, cementum, and periodontal ligament (new attachment apparatus). Part II of this study compared the healing of intrabony defects with and without the placement of decalcified freeze-dried bone allograft (DFDBA) in a submerged environment. The most apical level of calculus on the root served as a histologic reference point to measure regeneration on root surfaces exposed to the oral environment. Biopsies were obtained at 6-months and evaluated histometrically by two investigators unaware of the treatment performed. Data from 9 patients with 30 grafted defects and 13 nongrafted defects were submitted for statistical analysis. Results indicate that in a submerged environment significantly more new attachment apparatus (P less than .05) and new bone (P less than .05) formed in grafted than nongrafted sites. Significantly greater loss of alveolar crest height occurred in nongrafted than grafted defects (P less than .05); regeneration of new attachment apparatus, new bone, and new cementum occurred more frequently in grafted than nongrafted defects. There was a greater chance for the regeneration of a connective tissue attachment in nongrafted intrabony defects than in grafted defects; new cellular cementum formed equally well on old cementum, dentin, or both old cementum and dentin in the same defect. The periodontal ligament was oriented parallel, perpendicular, or both parallel and perpendicular in the same defect; and, no extensive root resorption, ankylosis, or pulp death was observed in grafted or nongrafted defects.

Alveolar Process↗
PubMed1989

Histologic evaluation of new attachment apparatus formation in humans. Part III.

There is still controversy as to the role of bone grafting materials in the formation of a new attachment apparatus and component tissues (bone, cementum, and periodontal ligament). The purpose of this study was to compare the healing of intrabony defects with and without the placement of decalcified freeze-dried bone allograft (DFDBA) in a nonsubmerged environment in humans. The most apical level of calculus on the root served as a histologic reference point to delineate root surfaces exposed to the oral environment and to measure new attachment apparatus and new component tissue formation. Free gingival grafts were placed over grafted and nongrafted defects to retard epithelial migration. Biopsies were obtained at 6 months and regeneration was evaluated histometrically. Data from 12 patients with 32 grafted and 25 nongrafted defects were submitted for statistical analysis. Results indicate that in nongrafted defects, a long junctional epithelium formed along the entire length of exposed root surfaces and often extended apical to the calculus reference notch. Free gingival grafts did not enhance regeneration of a new attachment apparatus, new cementum, new connective tissue, or new bone in nongrafted defects. The formation of a new attachment apparatus was observed when intrabony defects were grafted with DFDBA (x1.21 mm); significantly more new attachment apparatus (P less than .005), new cementum (P less than .005), new connective tissue (P less than .05), and new bone (P less than .0001) formed in intrabony defects grafted with DFDBA than in nongrafted defects. There was a greater chance for regeneration of a new attachment apparatus and component tissues in grafted defects than in nongrafted defects. New cellular cementum formed on old cementum and dentin but more often formed over both in the same defect). The periodontal ligament was more frequently oriented perpendicular to the root; there was greater loss in alveolar crest height in nongrafted than grafted defects (P less than .05); and extensive root resorption, ankylosis, and pulp death were not observed in grafted or nongrafted defects.

Analysis of Variance↗
PubMed1989

Determination of antigen concentration in tissue sections by immunodensitometry.

Our aim was to determine whether density of immunolabeling can be used to estimate the amount of an antigen in a tissue. The biological model was the pancreatic insulin-containing B cell. The insulin content of the pancreas of Wistar rats was decreased by five injections of glibenclamide (0.5, 1, or 2 mg/kg) every 12 hours. After resection of the whole pancreas specimens were taken for insulin extraction and measurement by radioimmunoassay and for immunocytochemistry. The sections were treated either by a polyclonal anti-insulin serum at 1/500 or 1/3000 and peroxidase-antiperoxidase complex or by a monoclonal anti-insulin serum at 1/500 and indirect immunoperoxidase. Peroxidase was revealed by diaminobenzidine. The density of immunostained B cells was determined with an automatic image analyzer (Ibas 2000, Kontron, FRG). Compared with controls, pancreatic insulin concentration was decreased by about 40, 60, and 85% in rats treated by the three doses of glibenclamide. A strong correlation was found between the insulin concentration and the optical density of islets under certain conditions: with the monoclonal anti-insulin serum (r = 0.90) and with the polyclonal anti-insulin serum at a high dilution (r = 0.95) but not at a low dilution (r = 0.13). With the latter, the optical density was high even in islets with reduced insulin content. In conclusion, a low dilution of antiserum should be used to detect cells with a small amount of antigen, whereas a higher dilution makes it possible to estimate the antigen concentration in the tissue. Thus, under appropriate conditions, a linear relationship exists between the optical density of the immunostained material and the concentration of immunoassayable antigen. This technique may thus prove useful in evaluating the functional state of cells, in particular secretory cells, under normal or pathological conditions.

Animals↗
PubMed1989

Detection of phosphatase production by Staphylococcus species: a new method.

The ability of staphylococci to produce phosphatase is an important character in the identification of species in the genus. Current methods are slow and difficult to interpret. A test is described which uses p-nitrophenyl phosphate as the substrate. It was evaluated by testing 1035 reference and clinical strains, and also compared with an alternative method. All strains of Staphylococcus aureus and 83% of Staphylococcus epidermidis were phosphatase positive: all strains of Staphylococcus saprophyticus were negative. The method proved to be an accurate, reliable, economic and relatively rapid technique to detect phosphatase production.

Agar↗