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Biomedical subjects

M Michel

Publications and source records attributed to M Michel.

At least 91 records · Page 5Linked to original sources
PubMed1995

Cerebral vasculitis after interleukin-2 therapy for renal cell carcinoma.

We report one patient with paralysis of the right upper extremity, bilateral cerebellar syndrome, and cognitive changes after treatment with interleukin-2 for metastatic renal cell carcinoma. Focal neurologic disturbances were associated with multiple images of cerebral infarcts but also with extraneurologic signs and autoantibodies. We suggest that this is a case of cerebral vasculitis with an autoimmune mechanism triggered by interleukin-2 therapy.

Adult↗
PubMed1995

Vitrification of articular cartilage by high-pressure freezing.

For more than 20 years, high-pressure freezing has been used to cryofix bulk biological specimens and reports are available in which the potential and limits of this method have been evaluated mostly based on morphological criteria. By evaluating the presence or absence of segregation patterns, it was postulated that biological samples of up to 600 microns in thickness could be vitrified by high-pressure freezing. The cooling rates necessary to achieve this result under high-pressure conditions were estimated to be of the order of several hundred degrees kelvin per second. Recent results suggest that the thickness of biological samples which can be vitrified may be much less than previously believed. It was the aim of this study to explore the potential and limits of high-pressure freezing using theoretical and experimental methods. A new high-pressure freezing apparatus (Leica EM HPF), which can generate higher cooling rates at the sample surface than previously possible, was used. Using bovine articular cartilage as a model tissue system, we were able to vitrify 150-micron-thick tissue samples. Vitrification was proven by subjecting frozen-hydrated cryosections to electron diffraction analysis and was found to be dependent on the proteoglycan concentration and water content of the cartilage. Only the lower radical zone (with a high proteoglycan concentration and a low water content compared to the other zones) could be fully vitrified. Our theoretical calculations indicated that applied surface cooling rates in excess of 5000 K/s can be propagated into specimen centres only if samples are relatively thin (< 200 microns). These calculations, taken together with our zone-dependent attainment of vitrification in 150-micron-thick cartilage samples, suggest that the critical cooling rates necessary to achieve vitrification of biological samples under high-pressure freezing conditions are significantly their (1000-100,000 K/s) than previously proposed, but are reduced by about a factor of 100 when compared to cooling rates necessary to vitrify biological samples at ambient pressure.

Animals↗
PubMed1995

A subset of patients with recurrent spontaneous abortion is deficient in transforming growth factor beta-2-producing "suppressor cells" in uterine tissue near the placental attachment site.

PROBLEM: To determine if patients with unexplained recurrent miscarriage have a deficiency of decidual immunosuppressor cells that produce transforming growth factor beta type 2, as has been found in mice with abortion due to rejection and/or trophoblast failure. METHODS: Decidual biopsy specimens were taken as near to the placental attachment site as possible under ultrasound guidance from first trimester legal termination (control) patients with recurrent miscarriage and non-viable pregnancy, and from patients with sporadic missed abortion. The tissue was tested for TGF beta-2+ suppressor cells by in situ hybridization, immunohistochemistry, and analysis of supernatants. RESULTS: TGF beta-2-related suppressor molecules similar but not identical to those identified in pregnant mice were released by decidual lymphoid cells. Fifty percent of 14 recurrent miscarriage patients showed a lack of suppressor cells and 59% were subnormal in comparison to 20 controls and 5 sporadic miscarriage patients, where 80-85% of the patients had detectable suppressor cells. CONCLUSIONS: Suppressor cell deficiency is compatible with a role for rejection and/or trophoblast failure in some patients with recurrent miscarriage. Presence of suppressor cells in most patients with missed abortion (4/5) is compatible with an alternative cause of fetal death, similar to findings reported in genetic fetal death mice.

Abortion, Habitual↗
PubMed1995

Membrane permeabilization by different regions of the human immunodeficiency virus type 1 transmembrane glycoprotein gp41.

The transmembrane glycoprotein (gp41) of human immunodeficiency virus type 1 (HIV-1) has been implicated in the cytopathology observed during HIV infection. The first amino acids located at the amino terminus are involved in membrane fusion and syncytium formation, while sequences located at the carboxy terminus have been predicted to interact with membranes and modify membrane permeability. The HIV-1 gp41 gene has been cloned and expressed in Escherichia coli cells by using pET vectors to analyze changes in membrane permeability produced by this protein. This system is well suited for expressing toxic genes in an inducible manner and for analyzing the function of proteins that modify membrane permeability. gp41 enhances the permeability of the bacterial membrane to hygromycin B despite the low level of expression of this protein. To localize the regions of gp41 responsible for these effects, a number of fragments spanning different portions of gp41 were inducibly expressed in E. coli. Two regions of gp41 were shown to increase membrane permeability: one located at the carboxy terminus, where two highly amphipathic helices have been predicted, and another one corresponding to the membrane-spanning domain. Expression of the central region of gp41 comprising this domain was highly lytic for E. coli cells and increased membrane permeability to a number of compounds. These findings are discussed in the light of HIV-induced cytopathology and gp41 structure.

Base Sequence↗
PubMed1995

Results from the NHS breast screening programme 1990-1993.

OBJECTIVE: To present results from the NHS breast screening programme (NHSBSP) for the three year period 1990 to 1993, and to examine the extent to which interim targets are being met. METHODS: Data have been collated from all screening programmes in the United Kingdom on standard "Korner" returns, supplemented for the year 1991/92 by data from the radiology quality assurance programme. Most of the data refer to the prevalent screening round, but some data on rescreening are also available. RESULTS: The total cancer detection rate at prevalent screens was 6.0/1000, 18% being in situ cancers; the detection rate of invasive cancers < or = 10 mm in diameter was 1.3/1000, but data on size were missing for 12% of cancers. Referral rates were significantly lower for programmes using two view mammography at the prevalent screen than for those using single view, and cancer detection rates were significantly higher. For prevalent screens over the three year period, 70% of programmes had a referral rate of < or = 7%, 87% had a benign biopsy rate of < or = 5/1000, and 79% had a cancer detection rate of > or = 5/1000. By contrast, only 30% of programmes appeared to meet the target detection rate of > 1.5/1000 for invasive cancers < or = 10 mm in diameter. CONCLUSIONS: While the majority of interim targets are being met by the NHSBSP, the rate of detection of small invasive cancers requires careful monitoring. Collection of more accurate data on size of cancers and interval cancer rates will give a better indication of progress towards the target mortality reduction.

Aged↗
PubMed1995

[Long-term results of cardiac transplantation].

Between 1982 and 1992, 73 patients who had undergone cardiac transplantation and survived the hospital period, were followed up. The actuarial survival was 86%, 65% and 40% at 1, 5 and 7 years. The main causes of the 14 secondary deaths were infection (4), acute rejection (3) and cancer (3). Survival was complicated by acute rejection (1.07 episodes/patient), infection (0.7 episode/patient), cancer, hypertension and renal failure, graft dysfunction and other more secondary side effects. After analysing all the complications, the authors evaluated the quality of long-term survival after cardiac transplantation which allowed one patient out of two to return to normal living but with the threat of secondary graft dysfunction.

Actuarial Analysis↗
PubMed1995

[Mortality due to bronchopulmonary cancers in workers of 2 foundries].

A mortality study was carried out in two factories producing stainless steel in order to assess lung cancer risk among workers employed in coke oven, blast and open hearth furnaces, foundry, electric furnace, hot and cold rolling mills and pickling areas. Occupational exposures of interest were chromium compounds, nickel compounds, polycyclic aromatic hydrocarbons (PAH), silica and asbestos. All male workers having at least one year of employment between 01.01.1960 and 31.12.1990 were followed up for mortality. The vital status was assessed from birth place registries. Complete job histories since date of first employment were abstracted from the company files. The smoking habits of 50% of the cohort members were known from medical records. The observed number of deaths (obs) were compared with the expected ones based on regional rates with adjustment for age, sex and calendar time (Standardized Mortality Ratio, SMR). The cohorts included 6324 (factory 1) and 5270 (factory 2) workers. The overall mortality did not differ markedly from that expected in both factories: SMR = 0.95 (obs = 1540, p = 0.05) in factory 1 and SMR = 1.06 (obs = 916, non-significant) in factory 2. SMRs for lung cancer did not differ from unity, respectively 0.99 (obs = 105) and 1.00 (obs = 54), in whole cohorts. Non-significant lung cancer excesses were observed among workers of some workshops where exposures of interest might have occurred: coke oven (SMR = 2.04), blast furnace (SMR = 1.36), open hearth furnace (SMR = 1.75), hot rolling mills (SMR = 1.29). These processes, however, are no longer involved in the study factories. Furthermore, no lung cancer excess was observed among workers employed in current workshops: electric furnaces and cold rolling mills.

Adult↗
PubMed1994

Effect of the bacteriocin carnocin CP5 and of the producing strain Carnobacterium piscicola CP5 on the viability of Listeria monocytogenes ATCC 15313 in salt solution, broth and skimmed milk, at various incubation temperatures.

Carnobacterium piscicola CP5, isolated from French mould-ripened soft-cheese, produced a bacteriocin named carnocin CP5 in a wide range of incubation temperatures, from 4 degrees C to 30 degrees C. The ability of a crude bacteriocin, of a partially-purified form, and of the producer strain to inhibit growth of Listeria monocytogenes ATCC 15313 was examined in salt solution, broth and skimmed milk between 4 degrees C and 30 degrees C. When carnocin CP5 was added to a L. monocytogenes ATCC 15313 culture, an adsorption on cells and a bactericidal effect with a cell lysis occurred. At 30 degrees C, with carnocin CP5 or with C. piscicola CP5, a transitory bactericidal effect was observed. Subsequent experiments at 4 degrees C, 7 degrees C or 15 degrees C, showed a more prolonged bactericidal effect. Thus at 7 degrees C, partially-purified carnocin CP5 reduced an initial population level of L. monocytogenes of 10(3) cfu/ml to non-detectable level within 7 days. However, in some cases, with extended incubation, the carnocin CP5 effect was no longer visible, the L. monocytogenes population grew again. This phenomenon was probably due to the presence of a sub-population of bacteriocin-resistant variants.

Animals↗
PubMed1994

Contact dermatitis from a textile flame retardant.

We report a case of contact sensitivity to Flammentin ASN, a flame retardant used on cotton and wool. The patient was a painter who was protecting his face with a white cotton cap. He presented with eczema of the forehead at the sites of cap contact. Patch tests with the treated cap and flame retardant were positive; a formaldehyde patch test was negative. Flame retardants are used in construction, materials and textiles. Contact sensitivity is rarely described and we compare our case to those published in the literature.

Adult↗
PubMed1994

ANG II receptor expression and function during phenotypic modulation of rat aortic smooth muscle cells.

Angiotensin II (ANG II) receptors were investigated in primary cultured rat aortic smooth muscle cells (SMC) that expressed either a proliferative phenotype (during the growth phase) or a contractile phenotype (at postconfluence). For each phenotype, alpha-smooth muscle actin expression, 125I-labeled ANG II specific binding, D-myo-inositol 1,4,5-triphosphate [Ins(1,4,5)P3] production, and ANG II-mediated increases in intracellular calcium (Cai2+) were studied. In both phenotypes, 1) ANG II-specific high-affinity binding (KD 0.5 +/- 0.1 nM and Bmax 196 +/- 106 pmol/mg protein in proliferative state, KD 1.5 +/- 0.3 nM and Bmax 560 +/- 299 pmol/mg protein in postconfluent state) was entirely inhibited by the selective AT1-antagonist losartan as well as by [Sar1,Ala8]ANG II and ANG III; 2) the AT2-antagonist CGP 42112A was ineffective, except at very high concentrations (> or = 10 microM); 3) the specific binding of ANG II was inhibited by guanosine 5'-[gamma-thio]triphosphate; and 4) ANG II induced a losartan-sensitive increase in Ins(1,4,5)P3. In postconfluent cultures, ANG II elicited a rapid biphasic elevation in Cai2+, which was abolished by losartan, whereas in growing cultures, this response was either absent or greatly attenuated. It is concluded that AT1-receptors coupled to phospholipase C via a G protein are expressed in the proliferative as well as in the contractile SMC phenotype and that their coupling to Cai2+ release is impaired in the proliferative phenotype. No evidence for AT2-receptor expression during phenotypic modulation of SMC was found.

Actins↗
PubMed1994

Therapeutic time window and dose response of the beneficial effects of ketamine in experimental head injury.

BACKGROUND AND PURPOSE: The aim of this study was to determine the time and dose response of the therapeutic effects of the N-methyl-D-aspartate receptor antagonist ketamine in experimental head injury. METHODS: Sixty-six male Sprague-Dawley rats were divided into eight groups. Groups A, B, and C were surgically prepared but received no trauma. Groups D through H received a nonpenetrating impact to the left cranium. Group A (n = 7) received no treatment. Groups B (n = 4) and C (n = 5) received 60 and 120 mg/kg IP ketamine, respectively. Group D (n = 8) received no treatment. Groups E (n = 8) and F (n = 7) received 120 and 180 mg/kg IP ketamine, respectively, 1 hour after head trauma. Groups G (n = 7) and H (n = 9) were treated with 180 mg/kg IP ketamine 2 and 4 hours after head trauma, respectively. Neurological severity score (NSS, 0 through 25 from no injury to severe injury) was determined at 1, 24, and 48 hours after head trauma. After death at 48 hours, cortical slices were taken adjacent to the lesion on the traumatized hemisphere and from comparable sites in the contralateral hemisphere for determination of tissue specific gravity and water content. Brains were then placed in 4% formaldehyde, and the volume of hemorrhagic necrosis was measured 4 days later. NSS was compared within and between groups using the Kruskal-Wallis test for repeated measurements and Mann-Whitney U test for post hoc testing. Water content, specific gravity, and hemorrhagic necrosis were compared within and between groups using two-way ANOVA followed by Fisher's protected least significant difference procedure. A value of P < .05 was considered statistically significant. RESULTS: Head trauma alone increased NSS, decreased specific gravity, increased water content, and caused cerebral infarction in the injured hemisphere. Ketamine given in two time-dose regimens, 180 mg/kg IP at 2 hours (group G) and 120 mg/kg IP at 1 hour (group F) after trauma, improved NSS from 11.6 +/- 1.7 and 14.4 +/- 0.8 at 1 hour to 4.4 +/- 1.3 and 8.0 +/- 1.4 (mean +/- SEM) at 48 hours, respectively (P < .03). Compared with the untreated group (group D), 180 mg/kg IP ketamine given at 2 and 4 hours after head trauma decreased the volume of hemorrhagic necrosis from 37.1 +/- 9.5 mm3 to 10.1 +/- 3.8 and 15.3 +/- 3.6 mm3, respectively (P < .05). Brain tissue specific gravity and water content at 48 hours were not significantly different between treated and untreated groups. There was no difference in rectal and temporalis muscle temperature between groups. CONCLUSIONS: We conclude that 180 mg/kg IP ketamine was effective in ameliorating neurological dysfunction after head trauma in rats when the administration time was delayed for 1 hour to 2 hours but not after 4 hours. When given at 1 hour after head trauma, ketamine at 120 mg/kg but not 60 mg/kg is effective in reducing neurological damage after head trauma.

Analysis of Variance↗
PubMed1994

Photocontact allergy to oxybenzone: ten years of experience.

Intolerance of sunscreen agents has often been reported in the literature. This mainly comprises photosensitization to sunscreens such as oxybenzone. The aims of this study were to establish the incidence of photocontact allergy to oxybenzone and its relationship with the use of other cosmetics. From 1982 to 1992 we performed photopatch tests on 283 patients with suspected photodermatosis. Forty-six patients (16%) had positive reactions: 61 positive photopatch tests and 9 positive patch tests. Photocontact allergy to sunscreens was divided into 2 main groups: 35 cases to oxybenzone and 17 cases to para-aminobenzoic acid and its derivatives. Among our 35 cases of photoallergy to oxybenzone, more than one third had photoallergy to a daily moisturizer that contained oxybenzone.

4-Aminobenzoic Acid↗
PubMed1994

Contact photosensitivity to nonoxynol used in antiseptic preparations.

Nonoxynols are nonionic surface-active agents used as surfactant in numerous cosmetic products and antiseptic preparations. Recently nonoxynol contact allergy has been described. We report two patients who presented a contact photosensitivity to nonoxynol 10 contained in Hexomédine transcutanée. Among 32 control subjects, we found 13 positive photopatch tests to Hexomédine transcutanée and 4 positive photopatch tests to nonoxynol 10. Surprisingly, the authors observed that only undiluted nonoxynol was phototoxic.

Administration, Cutaneous↗
PubMed1993

[Vancomycin in meningitis caused by penicillin G resistant Streptococcus pneumoniae].

We report two cases of penicillin G-resistant pneumococcal meningitis in adults, with clinical and bacteriological failure of amoxicillin and negative or incomplete response to third generation cephalosporins. Meningitis occurred in a man treated for myeloma and in an elderly woman under prolonged intermittent amoxicillin therapy for chronic otitis. Such situations are known as exposing to pneumococcal meningitis and to resistance of the strain involved to penicillin G. Both patients were cured by vancomycin in continuous infusion associated with rifampicin or fosfomycin. Contrary to third generation cephalosporins, which have higher minimal inhibitory concentrations, vancomycin and rifampicin are still fully active against penicillin G-resistant pneumococcal strains. Thus, vancomycin administered in continuous infusion and associated with rifampicin and fosfomycin deserves to be tried as first-line treatment of pneumococcal meningitis in patients at risk of resistance to penicillin G.

Aged↗
PubMed1993

The treatment of 783 keloid scars by iridium 192 interstitial irradiation after surgical excision.

PURPOSE: the aim of this study is to confirm the effectiveness of irradiation associated with surgery in the treatment of keloids, to precise the factors favoring the recurrence of these keloids, and to evaluate the risk of recurrence, according to their initial distinctive features. METHODS AND MATERIALS: between 1977 and 1988, 544 patients, with a total of 855 keloids, were treated by interstitial radiotherapy immediately following total excision. RESULTS: recurrence rate is 21%, as against 50 to 80% for surgery alone, according to most authors. This recurrence rate is about the same as for external radiotherapy, but we prefer our method for practical reasons (cost, equipment, radiobiology, technique). Ninety percent of recurrences occurred in the year following therapy, which proves that a follow-up time of at least 12 months is needed for a study of keloids. In our experience, the keloids that are the most likely to recur are the largest and those giving rise to most symptoms. Bruising and loosened stitches, but in particular infection during therapy, largely favor a recurrence. In our series, the symptoms disappeared or were much improved in 80% of cases, and the cosmetic result was judged good by 75% of the patients. CONCLUSION: the results of this study proves the effectiveness of the method linking surgical excision and Iridium 192 interstitial irradiation and shows the importance of the sterile conditions of the treatment.

Adolescent↗