Biomedical subjects
Publications and source records attributed to B Lambert.
We report infection with Trichomonas vaginalis in four sexually abused girls; two of these patients are unique in that they were premenarchal. We discuss the clinical features in premenarchal and postmenarchal children and relate infection to the likelihood of prior sexual abuse.
After ablation of an autonomously functioning thyroid nodule resulting from an adenoma, a previously suppressed scintigraphic image of a thyroglossal duct was visualised.
The frequency of sister-chromatid exchange (SCE) was studied in cultures of human lymphocytes exposed to vinyl acetate (VA) or acetaldehyde (AA) for various time periods and in different phases of the cell cycle. Equimolar concentrations (0.1-2.4 mM) of VA and AA were found to induce very similar, dose-dependent increases of SCE. The SCE frequency in cells treated with VA was found to increase linearly with exposure times up to 24 h. Cells exposed to VA or AA in the late G1-phase of the cell cycle showed a 2-fold higher SCE frequency than cells exposed in early G1. Cultures treated with VA in the first G1-phase showed a significant increase of SCE during 3 subsequent cell cycles. These results indicate that (1) AA is likely to be responsible for the SCE induction observed in VA-treated cells, (2) the SCE-inducing activity of AA persists for several cell cycles in vitro, and (3) removal of SCE-inducing AA-damage occurs during G1. Taken together, the data suggest that AA has a slow turn-over in human lymphocytes in vitro, and may accumulate in the cells, possibly by forming reversible Schiff bases, and when released gives rise to SCE-inducing DNA cross-links.
Human leucocytes were incubated in the presence of vinyl acetate or acetaldehyde (10-20 mM) for 4 h at 37 degrees C in vitro. DNA damage was analysed by alkaline elution. None of the compounds induced a detectable increase in the frequency of DNA strand breaks. Cells exposed to 5 Gy of X-ray immediately after treatment and before alkaline elution showed a clear, dose-dependent retardation of the elution rate in comparison with X-irradiated control cells. These results demonstrate that both vinyl acetate and acetaldehyde induce DNA cross-links in human cells.
The chronic treatment (2 days or more) of cultured thyroid cells with 1-10 microM forskolin (forskolin-treated cells) sensitizes the response of adenylate cyclase to further acute stimulation by 100 microM forskolin or 10 mU/ml thyrotropin (TSH). This positive regulation, similar to that produced by 0.1 mU/ml TSH (TSH-treated cells), is obtained between 2 and 3 days of culture. The acute response to TSH or forskolin of cells treated for 4 days with forskolin increases with the concentration of forskolin present during the chronic treatment. This result is different from that obtained after a chronic treatment with TSH which induces refractoriness beyond 0.1 mU/ml. These cells are then desensitized to TSH but not to forskolin. When both agonists are mixed together, their acute effect is additive on control, TSH- and forskolin-treated cells. The chronic treatment of cultured thyroid cells with 1-10 microM forskolin produces, just like 0.1 mU/ml TSH, a chronic phospholipid effect characterized by enhanced incorporation of 32Pi into phosphatidylinositol (PI) and phosphatidic acid. The acute challenge of these cells with 100 microM forskolin evokes a reverse phospholipid effect, i.e. a decreased incorporation of 32Pi into PI. The acute stimulation of TSH-treated cells with TSH produces a reverse phospholipid effect whereas the acute stimulation of forskolin-treated cells with TSH gives a normal phospholipid effect as it does on control cells. These results show that the observed effects of TSH on cAMP accumulation and phospholipid turnover are not independent and are regulated in an inverse reciprocal pattern.
Data from 300 colposcopic cases were computerized to study the correlations between the colposcopic observations and the histologic and other data. Colposcopy was shown to be most useful in women under 35 years of age. Use of oral contraceptives (the Pill) seemed to relate to a higher level of successful colposcopic visualization and may even prevent the need for conization, based on a higher incidence of negative endocervical curettages. Although 14.5% of the cases were colposcopically undergraded and 17% overgraded when compared to the histopathology, the histologic predictability of the colposcopic observation of white epithelium and vascular changes (punctation and mosaicism) was excellent. Colposcopy remains an essential technique in the appraisal and management of cervical intraepithelial neoplasia.
In a patient with a prior history of cerebral abscess and cerebral ischemia, an unsuccessful perfusion lung scan led to a radionuclide angiocardiogram using an arm vein injection. This showed a total right-to-left (R-L) shunt from the superior vena cava (SVC) to the left atrium. Repeat radionuclide study, through a leg vein, demonstrated a moderate R-L shunt and an interpretable lung scan could be obtained. Catheterization and contrast cineangiogram did not provide the exact diagnosis, the preoperative conclusion being anomalous drainage of the SVC into the left atrium, with atrial septal defect (ASD) and partial anomalous pulmonary venous connection to the SVC. The operative diagnosis was high atrial (sinus venosus) septal defect. This example of major but clinically unsuspected R-L shunt emphasizes the value of performing a perfusion lung scan, preferably in conjunction with radionuclide angiocardiography in patients with a prior history of unexplained cerebral abscess or systemic ischemia. Implications of the site of an ASD on quantitation of L-R shunts by radionuclide methods are also discussed.
1-O-Alkyl, 2-acetyl sn-glycerylphosphorylcholine (platelet activating factor (PAF)-acether) originally described as a platelet activating factor, is effective on various parameters in different cells. It seemed interesting to us to test it on porcine thyroid cells cultured for 1 to 5 days in the absence (control cells) or in the presence of 0.1 mU/ml thyreostimulin (TSH cells). At concentrations ranging from 0.5 to 2.5 microM, PAF-acether inhibited significantly the accumulation of cyclic AMP resulting from a 5 min incubation of the cells with TSH (40 mU/ml) or forskolin (0.1 mM). PAF-acether alone did not affect basal cyclic AMP accumulation. The maximal inhibition was obtained on a 3 day culture and amounted to 40-50%. The inhibition was transient and vanished after a 30 min incubation. The effects of PAF-acether (0.5 microM) on phospholipid metabolism depended closely upon the physiological state of the cells and upon the age of the culture. When PAF-acether was incubated for 2 h with [32P]phosphate, it mimicked the effects of TSH, i.e. it increased phosphatidylinositol (PI) labelling on 1 day control cells (expected effect) and decreased it with 1 day TSH cells (reverse effects). The PAF-acether effect was rapid in onset. After cell prelabelling for 2 h in the presence of TSH, PAF-acether added for 15 min completely counteracted the hormone effects on PI and phosphatidylcholine (PC) but increased the phosphatidic acid (PA) labelling. The effect of PAF- acether on PI labelling was partially antagonized by forskolin.(ABSTRACT TRUNCATED AT 250 WORDS)
The uptake of ethidium bromide by Escherichia coli K 12 cells has been studied by using 14C-labeled ethidium and spectrofluorometry on three E. coli strains: the first one (AB1157) has an ethidium-resistant phenotype; the second one derives from the first one after a single mutation (at 10 min on the E. coli genetic map) and has an ethidium-sensitive (Ebs) phenotype; the third one is the acrA strain which appeared to have the same phenotype as the Ebs strain. When the cells are in exponential growth, no ethidium enters wild-type cells, and a very limited amount of ethidium enters Ebs and acrA cells. Massive quantities of ethidium enter AB1157, Ebs, and acrA cells treated by uncouplers and respiring Ebs cells treated by the membrane ATPase-inhibitor dicyclohexylcarbodiimide. A small amount of ethidium enters cells treated in M9 succinate medium by metabolic inhibitors such as KCN or cells starved with oxygen in the same M9 medium. The amount of ethidium and ethidium dimer retained at equilibrium by either type of cell, and by cells infected by T5 phage, as well as the kinetics of influx and efflux, has been measured under a variety of situations (membrane energized or not, and/or membrane ATPase inhibited or not). Furthermore, it was shown that ethidium binds to both RNA and DNA when it enters CCCP-treated wild-type E. coli cells, whereas it binds mainly to DNA when it enters Ebs and acrA cells in exponential growth. As it will be discussed, it is difficult to account for the EthBr uptake by invoking only membrane functions and active transport. Therefore, it is proposed that the variations of the nucleic acid accessibility in E. coli cells might play a role in the control of this uptake. Accordingly, in ethidium-sensitive cells, the mutation would have caused a significant part of the chromosomal DNA (10-20%) to become accessible to ethidium. Hansen [Hansen M. T. (1982) Mutat. Res. 106, 209-216], after a study of the photobinding of psoralen to nucleic acids in the acrA mutant, also suggested that DNA environment was modified in acrA cells.
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The SCE frequency was studied in PHA-stimulated human lymphocytes exposed to various SCE-inducing agents in different stages of the cell cycle. Melphalan, HN2, MMS, and UV light were found to induce a higher SCE frequency in late G1 (18-24 hr after PHA stimulation) than in early G1 (1-6 hr after PHA) or G0 (before PHA stimulation). In contrast, CCNU induced more SCEs in early G1 than in late G1, and the adriamycin-induced SCE frequency was about the same after treatment in early and late G1. These results suggest that SCE-inducing lesions are being removed at different rates in human G1 lymphocytes. The removal of SCE-inducing HN2 lesions was found to be about 10 times more rapid in late G1 than in early G1, indicating the activation of a cross-link repair mechanism prior to DNA replication in human lymphocytes. Cells treated with MMS in the second G1 (after cultivation for about 55 hr in the presence of PHA and BrdUrd) showed a higher SCE frequency than cells treated with the same dose of MMS in the first G1. This result indicates that some type of interaction occurs between MMS damage and BrdUrd lesions in the DNA during replication, which leads to an enhanced induction of SCE. Analysis of SCEs induced during the 2 first vs. the third cell cycle in third-generation metaphases showed that most of the SCE-inducing damage caused by treatment with HN2 and melphalan in G1 of the first cell cycle are removed before the S phase of the third cell cycle, whereas damage caused by MMS and adriamycin seem to be more persistent. These observations suggest that the rate by which different types of SCE-inducing damage are removed or modified in resting (G0) of PHA-stimulated human lymphocytes can have a great influence on the SCE frequency. This is of practical importance in studies using SCE analysis to evaluate human exposure to suspected genotoxic agents in the environment.
Chromosome aberrations were studied in peripheral lymphocytes from 50 patients treated with melphalan against ovarian carcinoma. The chromosome analyses were carried out 4-132 months (mean 57 months) after the end of melphalan therapy. Most of the patients were studied several times during four years. The mean frequency of cells with chromosome and chromatid aberrations was 5.4% in the patients and 2.3% in an untreated control group. The highest aberration frequency (average 18%) was found in a patient who later developed gastric carcinoma. The dominating types of aberrations in the patients were chromosome exchanges occurring as single marker chromosomes or as multiple chromosome rearrangements. These types of aberrations were found in only 0.3% of the control cells as compared to 3.8% of the patient cells. Patients with a high total dose of melphalan (above 420 mg) and a long duration of the therapy (average 22.5 months) had a higher frequency of cells with aberrations (6.3%) than patients with a lower total dose (below 420 mg) and a shorter therapy (12 months) (4.2%). No additive effect of radiation therapy was observed on the aberration frequency.
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The induction of SCE was studied in PHA-stimulated human lymphocytes exposed to nitrogen mustard (HN2) or methyl methanesulfonate (MMS) for various time periods in the G1 phase. HN2 was found to induce about 10 times more SCE when cells were exposed in late G1 (24 h after PHA) as compared to early G1 (immediately after PHA). In contrast, only a small difference was observed between cells exposed to MMS in late or early G1. The results suggest that different types of SCE-inducing alkylating damage agents are removed at widely different rates in human G1-lymphocytes.
The male contraceptive agent gossypol was found to induce a dose related increase of DNA strand breaks in human fibroblasts in vitro at concentrations of 5 to 40 micrograms/ml. The effect was reduced in the presence of 2% fetal calf serum. A weak but reproducible increase in the SCE frequency was found in human lymphocytes treated for 1 hour in serum-free medium with 0.04 to 4 micrograms/ml of gossypol.
The stimulation of adipocyte-cyclase by isoproterenol decreases its sensitivity to adenosine, with, as a consequence, a decrease in its antilipolytic effect. The presence of insulin under conditions where its action on the phosphodiesterase activity is impaired, restores the responsiveness of adenylate-cyclase and of lipolysis to adenosine.
The effects of adriamycin (AM) on DNA repair replication, the frequency of sister-chromatid exchange (SCE), the rate of cell proliferation and the frequency of DNA strand breaks were studied in human cells in vitro. No repair replication was observed in lymphocytes exposed to AM in concentrations up to 10(-3) moles/l. DNA repair replication induced by UV and alkylating agents was not affected by a concentration of AM that completely inhibited cell proliferation (10(-6) moles/l). Fibroblasts exposed to AM at 10(-4) moles/l in the presence of hydroxyurea showed an increase of strand breaks and cross-links in DNA. When AM was added to UV-irradiated fibroblasts, there was an increase of DNA strand breaks in addition to the breaks caused by UV alone. Similar effects were observed in lymphocytes. A dose-dependent increase of SCE was observed in lymphocytes exposed to low concentrations of AM (less than 10(-7) moles/l). At higher concentrations the increase of SCE levelled off, and cell proliferation became severely inhibited. There was no evidence of removal of SCE-inducing damage in cells exposed to AM during G0 or G1. The level of SCE induced in the third cell cycle after treatment with AM was not different from that induced during the first two cell cycles. These results suggest that the various genotoxic and cytotoxic effects of AM are caused by different types of cellular damage. Moreover, AM-induced DNA damage persists for several cell cycles in human cells in vitro and seems to be resistant to repair activity.
To study the SCE-inducing effect of psoralen cross-links in the DNA of normal, human fibroblasts, cell cultures were exposed to PUVA (0.2-1 micrograms of 8-MOP per ml, followed by UVA irradiation at 0.04 J/cm2) and carefully washed to remove non-covalently bound psoralen. Some cell cultures were then given a second dose of UVA (1.1 J/cm2), either immediately after PUVA or 1-3 days later. By this type of treatment, cells with different proportions of DNA cross-links are obtained. The initial PUVA treatment will mainly give rise to psoralen monoadducts and only few cross-links in the DNA, and the second UVA irradiation will convert a number of the psoralen monoadducts into cross-links. SCE analysis was carried out on cells grown for 2 cell cycles in the presence of BrdUrd (10 mumoles/1). PUVA treatment alone did not induce an increase in the SCE frequency, whereas a clear increase of SCE was observed in cells treated with PUVA immediately followed by the second UVA dose. This PUVA + UVA-induced increase of SCE was also observed after incubation of the cells for 3 days at confluency, as well as when a period of 3 days at confluency was introduced between the PUVA exposure and the second irradiation with UVA. In contrast, the SCE frequency gradually returned to the normal level when PUVA + UVA-treated cells were allowed to proliferate for 1-2 days, or when a proliferation period of 2-4 days was introduced between the PUVA exposure and the second irradiation. Because the SCE frequency was not changed by the initial PUVA treatment but markedly increased by PUVA + UVA, it is concluded that psoralen cross-links are considerably more effective at inducing SCE than monoadducts. The results also indicate that SCE-inducing PUVA damage is removed very slowly if at all from the DNA of confluent cells. In contrast, repair functions that eliminate cross-links as well as monoadducts seem to become activated during cell proliferation.