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Biomedical subjects

F Roland

Publications and source records attributed to F Roland.

At least 19 recordsLinked to original sources
PubMed2001

Effects of two low-dose oral contraceptives containing ethinylestradiol and either desogestrel or levonorgestrel on serum lipids and lipoproteins with particular regard to LDL size.

This study was designed to determine the effects of two low-dose oral contraceptives, most frequently given in our area, monophasic desogestrel/ethinylestradiol (DG/EE) and triphasic levonorgestrel/ethinylestradiol (LNG/EE), on lipoprotein parameters, especially LDL particle size and HDL subclass distribution (determined by lipid-stained 2%-20% polyacrylamide gradient gel electrophoresis) in 37 healthy normolipidemic women aged 19 to 27 years. Lipid and lipoprotein parameters were measured before the start of treatment and in the third month of oral contraceptive use. Results reflected the estrogen-progestin balance. As compared with baseline values, with both formulations, plasma total cholesterol, phospholipids, and HDL3 cholesterol increased, and LDL-predominant peak size decreased, with a translation of LDL pattern A towards pattern I. With DG/EE, plasma triglycerides, apolipoproteins AI and B increased. With LNG/EE, LDL cholesterol increased, and HDL2 cholesterol decreased. All these modifications were moderate, within threshold limits. Estrogen-dominant monophasic DG/EE appears to be more favorable than progestin-dominant triphasic LNG/EE, since the reduction in LDL-predominant peak size is not associated with an increase in LDL cholesterol or with a decrease in HDL2 cholesterol.

Adult↗
PubMed1998

Transient lower extremity neurapraxia associated with radical perineal prostatectomy: a complication of the exaggerated lithotomy position.

PURPOSE: We assess the incidence and risk factors associated with lower extremity neurapraxia following radical perineal prostatectomy. MATERIALS AND METHODS: The medical records of 111 consecutive patients undergoing radical perineal prostatectomy at Duke University Medical Center between June 1994 and June 1995 were retrospectively reviewed. Patients were interviewed by telephone to ascertain whether symptoms had resolved. RESULTS: Neurapraxia developed in 23 patients (21%). Symptomatology was variable, including sensory and motor deficits of the lower leg and foot. Although lower extremity neurapraxia occurred in a significant number of patients undergoing radical perineal prostatectomy, it appeared to resolve in most. CONCLUSIONS: Careful attention to detail when positioning the patient and limiting the time in the exaggerated lithotomy position appear to be the most critical aspects to prevent neurapraxia.

Aged↗
PubMed1997

Remarkable ability of horse spleen apoferritin to demetallate hemin and to metallate protoporphyrin IX as a function of pH.

In previous studies it has been shown that reaction of crystalline horse spleen apoferritin with hemin leads to a protoporphyrin IX-apoferritin complex [Précigoux et al. (1994) Acta Crystallogr. D50, 739-743]. We show here the following. (i) Hemin binds to two classes of sites in horse spleen apoferritin at pH 8, each with a binding stoichiometry of 0.5 hemin/subunit; protoporphyrin IX also binds to horse spleen apoferritin with an apparent binding stoichiometry of 1 molecule of protoporphyrin IX/subunit. (ii) When Fe(III)-protoporphyrin IX binds to apoferritin, there is a pH-dependent loss of the metal ion, extremely slow at alkaline pH values (half-time of weeks) and much more rapid at acidic pH values (half-time of seconds below pH 5.0); maximum rates of demetallation are found at pH 4.0, and at lower pH values they decrease. (iii) Chemical modification of 11 carboxyl groups/subunit in horse spleen apoferritin does not affect hemin binding at alkaline pH values; however, it prevents hemin demetallation at acidic pH values. (iv) Hemin that has been demetallated at acidic pH values can be remetallated by increasing the pH; the rate of remetallation is greater at more alkaline pH values. (v) When around 20 atoms of iron/molecule are incorporated into horse spleen apoferritin and protoporphyrin IX is then bound, iron can subsequently be transferred to the porphyrin at pH 8.0. A mechanism is proposed to explain demetallation of heme, involving attack on the tetrapyrrole nitrogens of the protoporphyrin IX-Fe by protons derived from protein carboxylic acid groups and subsequent complexation of the iron by the corresponding carboxylates and binding of protoporphyrin IX to a preformed pocket in the inner surface of the apoferritin protein shell. The cluster of carboxylates involved is situated at the entrance to the pocket in which the protoporphyrin IX molecule is bound and has been previously identified as the site of iron incorporation into L-chain apoferritins. This appears to be the first example of iron removal and incorporation into porphyrins under relatively mild physiological conditions.

Animals↗
PubMed1996

["Tension-free" repair of inguinal hernia: laparoscopic (TAPP) versus open (Lichtenstein) repair].

In a prospective study, from June 1992 to February 1994 94 patients with 100 hernias were treated laparoscopically (TAPP) and from March 1993 to November 1994 100 patients with 108 hernias were treated with a Lichtenstein patch. Concerning duration of operation, postoperative outcome, complications and return to work, only minor differences were noted. Because of the more demanding and difficult technique, all TAPP procedures were performed by one surgeon, whereas all 11 surgeons of the department performed the Lichtenstein procedure without any learning curve, which demonstrates the simplicity of the procedure. A higher recurrence rate was found for the TAPP procedure (8 vs 0), however the learning curve has to be considered. The Lichtenstein operation is easy to learn and perform, safe, efficient, cheaper (750 DM) and therefore superior to the TAPP procedure. A planned randomized study was cancelled; laparoscopic hernia repair is no longer carried out in our department.

Adult↗
PubMed1991

Biochemical and biophysical investigations of the ferrocene-iron-loaded rat. An animal model of primary haemochromatosis.

Male Wistar rats fed with ferrocene had high hepatic iron loading (7.24 +/- 1.97 mg Fe/g tissue) after 6 weeks, principally located in lysosomes, which was comparable to the levels and distribution determined in human haemochromatosis. The two iron-storage proteins, ferritin and haemosiderin were isolated from the livers of the ferrocene-loaded rats and their iron cores were investigated by Mössbauer spectroscopy and inductively coupled plasma-emission spectrometry. Ferrihydrite was the predominant form of iron present in both ferritin and haemosiderin, while haemosiderin contained higher amounts of phosphorus, magnesium, calcium and barium, then either normal or ferrocene-loaded ferritin. Free-radical-mediated damage in the iron-loaded livers was inferred by the significant depletion of alpha-tocopherol in both the livers and subcellular hepatic lysosomal fraction, which inversely correlated with the increasing iron content (r = -0.61; P less than 0.05) and was associated with increased fragility of the lysosomal membranes.

Animals↗
PubMed1989

Investigation of a food-borne outbreak of salmonellosis among hospital employees.

An explosive outbreak of Salmonella enterocolitis developed in 27 hospital employees in an acute-care community hospital in Rhode Island in 1987. Salmonella typhimurium was isolated from the stools of 19 employees during the outbreak. In each patient the implicated organism had an identical antibiotic susceptibility pattern, biotype, plasmid profile, and restriction endonuclease digestion pattern. The outbreak was limited to health care workers and other hospital employees; there were no cases in hospitalized patients. Of the afflicted employees 96% ate in the hospital cafeteria on July 11 or 12, 1987. Food-specific attack rates, based on the dietary histories of ill employees and 50 healthy employees who ate in the cafeteria that weekend, indicated an association between the ingestion of salads and illness (p less than 0.01). One food service employee, in whom symptoms of abdominal cramping and diarrhea had developed 6 days earlier, had prepared the implicated foods. S. typhimurium with the identical characteristics of the outbreak strain was isolated from the stools of this food service employee. Environmental cultures and cultures of meat, poultry, and dairy sources for the cafeteria all showed negative results. Food service employees need to be counseled against working during any symptomatic enteric illness and require thorough instruction on hygienic food handling.

Adult↗
PubMed1989

A comparative mathematical evaluation of contour irregularity using form factor and PERBAS, a new analytical shape factor.

Contour irregularity was mathematically evaluated using two different analytical shape factors: (1) "form factor" (FF), a conventional type of shape analysis formula defined by the formula 4 pi A/P2, and (2) the "PErimeter Ratio Before and After Smoothing" (PERBAS). PERBAS values are obtained by first "smoothing" a contour that contains one or more concavities; surface projections are connected using straight lines and include only tangent lines that do not interest the nucleus, resulting in a convex wrap. Perimeters before and after smoothing were obtained using a MOP-3 computerized image analyzer. Using a series of computer-generated images, it was determined that FF was more sensitive than PERBAS to simple deformations of shape (i.e., having no contour concavities) whereas PERBAS was more specific for surface "roughness" (i.e., contour having at least one concavity). As an application to cancer diagnosis, 6 cases of Burkitt's lymphoma (BL) and 14 cases of Burkitt's-like lymphoma (BLL) were compared for nuclear contour roughness using both shape factors. The BLL group could be distinguished from the BL group on the basis of mean PERBAS values (P = .029), but not on the basis of mean FF values (P = .093). The BL group had a mean PERBAS value of 1.051 +/- 0.023 and a mean FF value of 0.790 +/- 0.068. The BLL group had a mean PERBAS value of 1.093 +/- 0.054 and a mean FF value of 0.723 +/- 0.094. Mean FF and PERBAS values, plotted in a bivariate graphic display, established morphometric shape domains. BL cases occupied a significantly smaller shape domain than did the BLL cases, indicating a greater heterogeneity among nuclear shapes in the latter group. Shape discrimination, in general, was greatly increased when both shape factors were used; this has a great potential for determining cancer diagnosis and patient prognosis.

Burkitt Lymphoma↗
PubMed1981

Mobilization of iron from ferritin by isolated mitochondria. Effects of species compatibility between ferritin and mitochondria and iron content of ferritin.

Mitochondria mobilize iron from ferritin by a mechanism that depends on external FMN. With rat liver mitochondria, the rate of mobilization of iron is higher from rat liver ferritin than from horse spleen ferritin. With horse liver mitochondria, the rate of iron mobilization is higher from horse spleen ferritin than from rat liver ferritin. The results are explained by a higher affinity between mitochondria and ferritins of the same species. The mobilization of iron increases with the iron content of the ferritin and then levels off. A maximum is reached with ferritins containing about 1 200 iron atoms per molecule. The results represent further evidence that ferritin may function as a direct iron donor to the mitochondria.

Animals↗
PubMed1980

Iron mobilization from ferritin by chelating agents.

The release of iron from horse spleen ferritin by the chelating agents desferrioxamine B, rhodotorulic acid, 2,3-dihydroxybenzoate, 2,2'-bipyridyl and pyridine-2-aldehyde-2-pyridyl hydrazone (Paphy) has been studied in vitro. Ferritin prepared by classical procedures involving thermal denaturation releases its iron less effectively than ferritin isolated by a modified procedure that avoids this step. Desferrioxamine B and rhodotorulic acid are the most effective in releasing iron from both preparations of ferritin. When FMN is added, iron release by desferrioxamine B, rhodotorulic acid, and 2,3-dihydroxybenzoate was effectively blocked, whereas both bipyridyl and Paphy showed a marked simulation. A substantial increase in iron release was also observed for bipyridyl and Paphy with ascorbate; a less important increase was noted for rhodotorulic acid. EDTA exerted a marked inhibition of iron release from ferritin with rhodotorulic acid, 2,3-dihydroxybenzoate, bipyridyl, and Paphy. The effects of citrate and oxalate on iron release by the chelators was small. The effect of the concentration of flavin on iron release from ferritin by bipyridyl and desferrioxamine B have been studied. Desferrioxamine is unable to mobilize FeII from ferritin following reduction by reduced FMN, whereas bipyridyl can rapidly complex the ferrous iron. The results are discussed in the context of our current concepts of storage iron mobilization in the treatment of iron overload.

Animals↗
PubMed1979

[Inhibition of Escherichia coli haemagglutinations by antibiotics].

Escherichia coli has been associated with a colonization factor antigen responsible for the bacterial adherence to the intestinal mucosa. This colonization factor is also responsible for haemagglutination. Among 32 antibiotics tested, only tetracyclines, chloramphenicol and nafcillin inhibit haemagglutination. Tetracycline hydrochloride, tetracycline phosphate and doxycycline are the most effective, followed by oxytetracycline, minocycline, chloramphenicol and nafcillin. Doxycline at a concentration at 0.8 mg/ml in buffered saline, chloramphenicol at 12.8 mg and nafcillin at 31 mg inhibit haemagglutination in 2 h. The inhibition of haemagglutination occurs both with E. coli susceptible and resistant to doxycycline. Pretreatment of crythrocytes with doxycycline does not prevent inhibition of haemagglutination where as pretreatment of E. coli does, suggesting that doxycycline acted on the bacteria. Once haemagglutination had occurred, doxycycline can reverse the haemagglutination, "unhooking" the bacteria from the erythrocytes. These data raise the possibility that some antibiotics may prevent adherence of E. coli to the intestinal mucosa, regardless of the susceptibility or resistance of the bacteria by a direct effect on the colonization factor antigen. Furthermore, some antibiotics may be able to detach the bacteria once adherence to the mucosa has occurred.

Anti-Bacterial Agents↗
PubMed1977

Humoral response in blood group P phenotype persons subjected to an avian environment.

The avian environment contains among many antigens, the blood group substance P1-P1 antigen is present in certain Enterobacteriaceae found in bird droppings. Examples include Enterobacter, Klebsiella, E. coli, Enterobacter Haffniae and Proteus. P2 persons exposed to the avian environment may develop anti-P1 activity. A greater percentage of precipitins to bird antigens was found in P2 than in P1 persons. In P1 persons seven out of twenty-eight (25%) had precipitins to bird droppings. In P2 persons, ten out of thirteen (77%) had anti-P1 activity and nine out of thirteen (69%) had precipitins to bird droppings. This greater response in P2 persons may be explained by the constant stimulation of these persons lacking the P1 antigen that triggers more response with other antigens in addition to the P1 antige. In the study of immunological responses to inhaled antigens, the blood group of the patients should be determined in order to assess the importance of constant stimulation by foreign material in persons lacking some blood group antigens.

Animals↗
PubMed1976

The P blood group system in pigeon breeders and pigeon breeder's disease.

A blood group P1-like antigen has been found in gram-negative bacilli isolated from pigeon droppings, in pigeon serum, and on pigeon red blood cells. As a probable resident of the environment of the pigeon loft, the antigen stimulated formation of anti-P1 antibody in eight of 11 pigeon breeders who belonged to the P2 blood group. Only one of 11 random hospitalized patients with the P2 blood phenotype had a detectable titer of anti-P1 antibody (P less than 0.01). The titer of anti-P1 antibody was not significantly different in symptomatic vs asymptomatic breeders. The presence or absence of anti-P1 antibody could not be correlated with any band of immunoprecipitates formed between pigeon breeder's serum and crude extract of pigeon droppings. The P antigen was identified in pigeon-dropping extracts of breeders with the P2 blood phenotype by inhibition of hemagglutination. We conclude that anti-P1 antibodies appear to be a component of the immunologic response to avian antigens of pigeon breeders but are probably unrelated to the pathogenesis of pigeon breeder's disease.

Alveolitis, Extrinsic Allergic↗