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Biomedical subjects

R Michel

Publications and source records attributed to R Michel.

At least 73 records · Page 4Linked to original sources
PubMed1994

Changes of concentrations of the elements Co, Cr, Sb, and Sc in tissues of persons with joint implants.

Elevated levels of Co and Cr were found in several organs of decreased implant bearers (CoCr-alloy/polyethylene joint prostheses) by means of instrumental and radiochemical neutron activation analysis as compared to normal persons. For comparative purposes, concentrations of the elements Co, Cr, Sb, and Sc were measured in heart, kidney, liver, and spleen of the patients and normal persons. For Cr determination, a new radiochemical separation technique with sufficiently low determination limit was employed. The importance of such investigations for studying possible carcinogenic effects of corrosion products and wear particles of metallic prostheses is mentioned.

Chromium↗
PubMed1994

Risk factors for low urinary citrate in calcium nephrolithiasis: low vegetable fibre intake and low urine volume to be added to the list.

Risk factors for low urinary citrate excretion were assessed in 34 consecutive male recurrent idiopathic calcium stone formers (RCSF) who collected two 24-h urines while on free-choice diet. Overt hypocitraturia (hypo-cit) was defined as UCit x V < 1.70 mmol/day, and 'low' citraturia (low-cit) as UCit x V between 1.70 and 2.11 mmol/day. Twenty-three RCSF had normocitraturia (normo-cit), six low-cit and five hypo-cit. UCit x V positively correlated with urine volume (VOLUME, r = 0.44, P = 0.009), vegetable fibre intake (fibers, r = 0.46, P = 0.009) and GI-alkali absorption (alkali, r = 0.47, P = 0.006), and volume, fibres and alkali tended to be lower among RCSF with low-/hypo-cit. A 3-day NH4Cl loading test (0.95 mEq/kg BW daily in 3 doses) was performed in RCSF as well as in 14 age-matched healthy male controls (C). On a plot of urine pH versus serum bicarbonate, 10 of 11 RCSF with low-/hypo-cit, but only six of 23 with normo-cit (P = 0.0004) fell off the normal range, indicating incomplete RTA. Two or more risk factors simultaneously occurred in only four of 23 RCSF with normo-cit, but in eight of 11 with low-/hypo-cit (P = 0.002). In conclusion, incomplete RTA is the most prevalent risk factor for low-/hypo-cit in RCSF, and decreases in vegetable fibres and urine volume emerge as two new risk factors for low urinary CIT.

Acidosis, Renal Tubular↗
PubMed1992

Conjunctival vaccination of pregnant ewes and goats with Brucella melitensis Rev 1 vaccine: safety and serological responses.

When Brucella melitensis strain Rev 1 vaccine (Rev 1) is administered by the standard method (1-2 x 10(9) viable bacteria injected subcutaneously), it may induce long-lasting serological responses and/or cause abortion in pregnant animals. The conjunctival route considerably reduces these drawbacks. In the present experiment a 1 x 10(8) CFU dose for both ewes and goats conjunctivally vaccinated at mid-pregnancy was tested for innocuousness (outcome of pregnancy, contamination of unvaccinated contact animals, duration of serological responses) in comparison with 3 x 10(8) CFU (ewes and goats), 1 x 10(9) and 3 x 10(9) CFU (ewes) doses. No reaction was observed at the time of vaccination, and the risk of environmental contamination with Rev 1, due to the conjunctival administration of the vaccine, is negligible. Abortions occurred later at surprisingly severe rates (over 60% of pregnant vaccinated animals), except in the 1 x 10(8) CFU ewes group (20%). Moreover, the serological reactions of the 1 x 10(8) CFU ewes which normally lambed were negative again as early as 12 weeks after vaccination. Although the dose of 1 x 10(8) CFU Rev 1 was safer for pregnancy than the standard dose mainly in ewes as compared to goats, the innocuousness was not yet sufficient to propose the former dose to indiscriminately vaccinate sheep and goats by the conjunctival route, whatever the age or physiological status.

Abortion, Veterinary↗
PubMed1991

Systemic effects of implanted prostheses made of cobalt-chromium alloys.

Systemic effects of Co-Cr alloy/polyethylene hip joint prostheses were investigated using instrumental neutron activation to determine the concentrations of up to 16 elements. First, in a prospective study whole blood and serum taken from 10 patients from 1 day before to 90 days after implantation were analyzed. Secondly, in a retrospective study whole blood and serum from 23 patients who had had prostheses in place for up to 18 years were analyzed. For comparison, normal trace element levels in humans were determined by analyzing whole blood and serum from 21 patients. Finally, various tissues and organs from two decreased implant patients were analyzed and compared with normal concentrations obtained from the analysis of five "normal" patients without implants. In agreement with other recent investigations, our analyses of normal serum, whole blood, tissues, and organs show that most previously defined "normal" trace element concentrations were too high, chiefly owing to contamination and insufficient blanks. A detailed discussion shows that for many elements the ranges of normal concentrations have to be revised. This conclusion is of particular importance with respect to the sometimes conflicting earlier reports of systemic effects of metal prostheses. In the work reported here, both the prospective and the retrospective investigations of serum and whole blood showed massive Co enrichments as a consequence of implant corrosion. The data show a wide range of individual burdening, ranging from practically no effect to the most extreme values. The analyses of tissues from the vicinity of the implants in the two deceased implant patients showed strong local effects of Co, Cr, Zr, and Hf, the latter two elements originating from the X-ray contrast media in the bone cement. The analyses of organs revealed significant Co and Cr enrichment in several tissues and organs. Consequently, it can be seen that implant corrosion is not an occurrence of merely local significance, but one that affects the trace element status of the entire organism.

Bioprosthesis↗
PubMed1991

Species identification and characterization of an Acanthamoeba strain from human cornea.

The isoenzyme pattern of an Acanthamoeba, stock H-1, isolated from a patient with keratitis (Krankenhaus Heidberg, Hamburg) was compared with that of two strains of A. quina-A. lugdunensis (302-2, 312-1), two stocks of A. lenticulata (45, 89-1) and one strain of A. rhysodes (302-1). The isolated stock showed glucose-6-phosphate dehydrogenase (G-6-PDH), beta-hydroxybutyric dehydrogenase (beta-HBDH), alcohol dehydrogenase (ADH) and superoxide dismutase (SOD) isoenzyme patterns similar to those of A. quina-A. lugdunensis but their acid phosphatase (AP) patterns differed. Furthermore, cyst morphology showed that the patient-isolated stock belongs to group II of the taxonomic classification of Acanthamoeba. This stock was not thermophilic and exhibited non-pathogenic properties after its intranasal instillation into NMRI mice, whereas it killed BALB/c mice. Immunofluorescent studies revealed the presence of antibodies against Acanthamoeba in the patient's serum. Immunoblotting experiments showed that a 45-kDa protein reacted with this serum. Such an antigen was also detected in A. quina-A. lugdunensis and A. lenticulata. Lectin reactions with Canavalia ensiformis, Ricinus communis-120, Lotus tetragonolobus, Ulex europaeus I, Helix pomatia, Arachis hypogaea, Triticum vulgaris, Glycine maxima, Bauhinia purpurea and Mycoplasma gallisepticum demonstrated that only the A. lenticulata stocks could not be distinguished and that the H-1 stock was more similar to the A. lugdunensis 302-2 strain than to the other acanthamoebae.

Acanthamoeba↗
PubMed1991

Isolation of Ewingella americana from a patient with conjunctivitis.

Ewingella americana (family Enterobacteriaceae) was isolated separately from both eyes of a 30-year-old woman. Clinical signs and symptoms included adhesive eyelids, itching and edematous upper and lower lids. Therapy with amoxicillin-clavulanate resulted in the relief of symptoms. Ewingella americana can be isolated worldwide, but seems to be a rare pathogen.

Adult↗
PubMed1991

A descriptive analysis of elite-level racquetball.

The results of the three experiments provide insight into the time/motion characteristics of racquetball and the physiological responses of elite-level racquetball players during competition. The maximum oxygen uptakes of the male and female athletes tested were relatively low in comparison to those of other elite-level sports, suggesting that aerobic demand, although necessary, is probably not a limiting factor at this level of racquetball play. Racquetball games at the elite level last from 10 to 15 min, and the distance covered by each player during this time is minimal. Even though the rest periods between rallies are from one to two times as long as the work intervals, the work intensity during the rallies is sufficient to produce an average heart rate of between 75 and 95% of maximum throughout most of a game. Although some lactic acid accumulates in the blood, the concentration remains at a steady state during a game (10 to 30% of maximum).

Adult↗
PubMed1991

Pancreatic gene expression is altered during acute experimental pancreatitis in the rat.

We investigated pancreatic gene expression in the rat in response to taurocholate-induced acute pancreatitis. Concentrations of transcripts encoding pancreatic protein showed noncoordinated alterations. Contents in amylase, trypsinogen I, chymotrypsinogen B, elastase 1, and procarboxypeptidase A mRNAs decreased by greater than 50% during the acute phase (days 0-2), whereas actin and lithostathine mRNAs increased 5 and 0.6 times, respectively, and pancreatitis-associated protein (PAP) mRNA increased greater than 200 times, indicating redirection of the pattern of gene expression. Synthesis of pancreatic proteins was also altered in a noncoordinated manner. During the acute phase, it decreased more for trypsinogen I and chymotrypsinogen B than for amylase and lipase, whereas synthesis of the PAP increased dramatically. For amylase and chymotrypsinogen B, we compared the patterns of changes in mRNA concentrations, rates of synthesis, and pancreatic contents. Changes in enzyme contents and synthetic rates were temporally correlated during the acute phase. On the contrary, changes in mRNA concentrations and enzyme synthesis were not coordinated, suggesting that control of synthesis partly occurred at the posttranscriptional level. It was concluded that induction of pancreatitis is accompanied by transcriptional and posttranscriptional modifications resulting in rapid and massive rearrangement of the pattern of pancreatic protein gene expression.

Acute Disease↗
PubMed1991

[Acanthamoeba, Naegleria and invertebrates in wet areas of physiotherapy equipment in hospitals].

In the course of investigations on the occurrence of primary free-living amoebae in different aquatic habitats, especially Naegleria and Acanthamoeba, we now investigated the moist areas in physiotherapeutic departments of 10 hospitals. As a result 61% of the swabs taken in those areas were positive with one or several species of amoebae cultivated on NN-agar according to Page. Among many other species observed during this study we were able to isolate 47 strains of Acanthamoeba and only two strains of Naegleria. The Naegleria-strains did not appear to be thermophilic. Therefore they are part of the N. gruberi-complex, which is considered to include only non pathogenic strains. Six from 47 strains of Acanthamoebae isolated revealed pathogenic characters as demonstrated in the MIT (Mice inoculation test). As a remarkable result four of these 6 strains with proven pathogenicity were not thermophilic at + 40 degrees C. Eventually all strains even not being thermophilic should in future be tested on pathogenicity. Additionally, nematodes and rotifers were isolated from several samples.

Acanthamoeba↗
PubMed1990

[Proliferative myositis].

We report on a 42-year-old woman showing a rapidly growing tumor on her left flank; it was removed by surgery. Histological examination revealed the typical picture of proliferative myositis. Since the clinical symptoms of this disease are nonspecific, the diagnosis always depends on histological evidence. Despite its rapid growth and its cellular pleomorphism, proliferative myositis is a reactive process and has to be differentiated histologically from sarcoma of the soft tissue.

Adipose Tissue↗
PubMed1990

[Degenerative changes in schwannoma (neurilemmoma)].

We report on a 51-year-old male patient showing a slowly growing, pedunculated, hairless tumor on the back of his head. The tumor grew up to the size of 4.2 cm in diameter, before it was removed by surgery. Histological examination revealed the typical picture of an ancient schwannoma (degenerated neurilemmoma). In spite of its highly atypical nuclei, the biological behavior of ancient schwannoma is benign, and it must be differentiated from malignant tumors of the nerve sheath.

Connective Tissue↗
PubMed1989

[The significance of amoebae and other protozoa in water conduit systems in dental units].

In a longitudinal study over a period of ten weeks, the water conduit systems of seven dental surgeries with a total of 20 dental units in which legionellae had been detected in an earlier study (3) were investigated as a complement to extended microbiological tests (4) for the occurrence of free-living amebae and other protozoa. In 96% of all water samples, one or several ameba species were detected. These included 14 strains of the genus Naegleria, but no acanthamoebae. The naeglerias isolated were not thermophilic and thus belong to the N. gruberi complex, which does not contain any pathogenic strains. In two water samples, two different species of small freeliving nematodes were demonstrated. The simultaneous investigation of samples from the warm water supply in the individual dental surgeries revealed an ameba contamination in 24.9% of the samples. A nonpathogenic strain of the genus Protacanthamoeba was demonstrated once. The possible role of the trophozoites of various ameba species as hosts for an intracellular proliferation of the legionella strains demonstrated at the same time (cf. 4) is discussed. The occasional protective intracellular inclusion of legionellae in trophozoites of various species and in cysts of acanthamoebae might be an explanation for the resistance of legionellae to disinfection measures which has been repeatedly observed. This observation will have to be taken into consideration in sterilization and disinfection projects.

Amoeba↗
PubMed1989

[In vivo sensitivity of Plasmodium falciparum to amodiaquine in the town of Edea (Cameroon)].

In the town of Edea, where falciparum malaria is hyperendemic, an in vivo study of amodiaquine sensitivity of the local strain of the parasite is performed in school children 6 to 12 years of age: 184 children with parasites in their blood and no chloroquine in their urine are given amodiaquine orally. In 96 children having taken 35 mg per kg body weight of amodiaquine base, none is any longer harboring parasites in his blood as soon as the second day following the end of the 3 days treatment (15 mg/kg body weight the first day, 12 mg/kg the second day and 8 mg/kg the third day). The 73 children having taken 27 mg/kg body weight of amodiaquine base are cleared of their parasites at the rate of 93% on the seventh day of the experiment. The 15 children having only taken 15 mg/kg body weight of amodiaquine base are cleared of their parasites at the rate of 54%. At the utilized doses, amodiaquine is generally well tolerated. Conjunctival hyperhaemia has only been observed as a secondary effect in 9 children among the 184 children treated but this side symptom disappeared soon after the end of the treatment. Aminotransferases blood levels are not modified in the course of the amodiaquine treatment.

Amodiaquine↗
PubMed1988

Effects of dimethylsulfoxide and the deep-freezing process on the infectivity, motility, and ultrastructure of Trypanosoma cruzi.

The effects of dimethylsulfoxide (DMSO, final concentration 5%) and the deep-freezing process on the infectivity (ID50), motility, and ultrastructure of nontreated and DMSO-treated Trypanosoma cruzi suspensions (PSG-3 buffer with 10% horse serum) were investigated prior to and after cryopreservation in liquid nitrogen. DMSO equilibration caused distinct suppression of motility and characteristic, fine structural alterations in numerous organelles, such as myelin-like structures in the cytoplasm and/or inside the mitochondrial apparatus, enlargement of the perinuclear space, endoplasmic reticulum, and mitochondrial cristae, as well as condensation of the kinetoplast with loss of its lamellar structure. There was no evidence of loss of infectivity in DMSO-treated parasites. DMSO-treated and deep-frozen organisms showed, however, very similar fine structural alterations, although damage occurring during freezing and thawing was more pronounced. Apart from the frequently enlarged kinetoplast and the loosening of its mitochondrial matrix, numerous trypanosomes revealed total disintegration of the kinetoplast-mitochondrion complex with loss of its whole matrix. Deep-frozen trypanosomes were significantly less infective to mice than nontreated organisms, and their motility was strongly suppressed. These results suggest that cryopreservation and thawing of T. cruzi may lead to severe damage of the mitochondrial apparatus and thus to heavy disorders of metabolic function, exhaustion of the metabolic pool, and finally, to death of such damaged trypanosomes, despite the use of DMSO as a cryoprotective agent.

Animals↗
PubMed1988

Species identification and virulence of Acanthamoeba strains from human nasal mucosa.

Using agarose isoelectric focusing, the isoenzymes of 19 Acanthamoeba strains were investigated. They had been isolated from nasal mucosa, and the species identification based on morphology of the cyst had previously been reported. The identification by isoenzymes differed from that by cystic morphology. Growth at 40 degrees C correlated with the species identification by isoenzymes. Six strains were identified as A. lenticulata, nine as A. mauritaniensis, one as A. rhysodes, and three belonged to the A. lugdunensis-A. quina complex. Several of the nasal A. lenticulta isolates proved to be highly virulent for mice.

Acanthamoeba↗
PubMed1988

Nonsecretory myeloma: a study on hypoimmunoglobulinemia.

In evaluating hypoimmunoglobulinemia in a patient with nonsecretory myeloma, studies of in vitro immunoglobulin synthesis were performed during a 3-year period. Impaired polyclonal response to mitogen stimulation associated with excessive suppressor activity was demonstrable at diagnosis. Despite successful chemotherapy, serum immunoglobulin levels remained depressed with a persistent impairment in polyclonal immunoglobulin synthesis but without evidence for excessive suppression. In nonsecretory myeloma, as in secretory myeloma, a defective B-cell response to differentiation signals may be a contributory mechanism in the hypoimmunoglobulinemia seen in this disease.

Agammaglobulinemia↗
PubMed1987

Force and fatiguability of sprouting motor units in partially denervated rat plantaris.

The contractile properties of single motor units of rat plantaris were measured in situ 7 days following muscle partial denervation, achieved by section of radicular nerve L4. Partially denervated muscles weighed less, generated weaker twitch and tetanic forces, and contained denervated fibers, as evidenced by indirect/direct stimulation force ratios less than 1. Fast motor units (over 90% of unit pool) showed elevated twitch and tetanic responses (222% and 171% of controls, respectively) and elevated twitch-to-tetanic force ratios. Although partial denervation did not alter the mean fatiguability of fast motor units, fewer proportions of units remained in the extreme categories of fatigue resistance, with a clustering of units in the intermediate ranges. Slow units, while showing elevated twitch and tetanic responses, did not change in fatiguability. Glycogen depletion of the fibers of two fast motor units in partially denervated muscles revealed the presence of fibers varying in size, and in staining intensities for succinate dehydrogenase and ATPase, within the same motor unit, as a result of motoneurone sprouting.

Animals↗