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Biomedical subjects

L Maas

Publications and source records attributed to L Maas.

11 recordsLinked to original sources
PubMed2001

Biological monitoring the exposure to polycyclic aromatic hydrocarbons of coke oven workers in relation to smoking and genetic polymorphisms for GSTM1 and GSTT1.

UNLABELLED: Occupational exposure to polycyclic aromatic hydrocarbons (PAH) increases the risk of developing lung cancer. Human exposure is often demonstrated by increased internal levels of PAH metabolites and of markers for early biological effects, like DNA adducts and cytogenetic aberrations. OBJECTIVE: This study aimed to assess whether the current exposure to PAH of coke oven workers in a Dutch plant induced biological effects, and to determine if these effects are influenced by tobacco smoking and by genetic polymorphisms for the glutathione S-transferase genes GSTM1 and GSTT1. METHODS: Urinary 1-hydroxypyrene (1-OHpyr) levels were used to monitor the internal dose, while the internal effective dose was assessed by monitoring PAH-DNA adducts, DNA strand breaks (Comet assay), sister-chromatid exchanges (SCE) and cells with a high frequency of SCE (HFC) in lymphocytes together with micronuclei (MN) in exfoliated urothelial cells. RESULTS: Occupational exposure to PAH resulted in statistically significant increased 1-OHpyr levels (P<0.001), but it did not cause a significant induction of SCE, HFC, MN, DNA strand breaks or DNA adducts. Smoking caused a significant increase of 1-OHpyr (P<0.05), SCE (P<0.001), HFC (P<0.001) and DNA adducts (P<0.05), but not of MN or DNA strand breaks. Following correction for the smoking-related effects, no occupational induction of the effect biomarkers could be discerned. Multi-variate analysis did not show a significant influence of GSTM1 and GSTT1 polymorphisms on any biomarker. Also no significant interactions were observed between the various biomarkers. CONCLUSION: This study shows that in the examined plant, the occupational exposure to PAH does not result in measurable early biological effects

Adult↗
PubMed2000

Effect of a dioxin-like PCB (CB 126) on the biotransformation and genotoxicity of benzo

Two experiments were performed to study the interaction between benzo[a]pyrene (BaP) and the planar, dioxin-like PCB congener 3,3',4,4',5-pentachlorobiphenyl (CB 126) in the flatfish dab (Limanda limanda). The first experiment involved four groups. Group I was treated with 10 µg/kg CB 126, group II was treated with 2 mg/kg BaP, group III was first treated with 10 µg/kg CB 126 and exposed to 2 mg/kg BaP 6 days later, and group IV was a control group. The second experiment was similar, except that the BaP dosage level was increased to 50 mg/kg. Pre-treatment with 10 µg/kg of CB 126 always caused the induction of hepatic cytochrome P450 1A (CYP1A), as measured by significant increases of the model reaction 7-ethoxyresorufin-O-deethylase (EROD) in microsomal preparations. Treatment of dab with BaP caused a significant EROD induction at the 50 mg/kg, but not at the 2 mg/kg level. Concurrent with EROD induction by either CB 126 or 50 mg/kg BaP, was a significant change in the biliary metabolite pattern in favour of 1-hydroxybenzo[a]pyrene and 3-hydroxybenzo[a]pyrene and towards a lower fraction of the procarcinogen BaP-7,8-dihydrodiol (7,8-DIOL). Pre-treatment with CB 126 did not cause an increase of hepatic BaP DNA adducts formed after treatment with either 2 or 50 mg/kg BaP. Glutathione S-transferase (GST) activities remained also unaffected by any of the treatments. The results of this study suggest that the pattern of BaP metabolites in bile depends on the level of CYP1A induction. Moreover, the concurrence of a potent CYP1A inducer and BaP does not necessarily lead to an increase in DNA adduct levels in liver tissue. The observation that the level of 7,8-DIOL is decreased despite a higher (CYP1A mediated) EROD activity explains, at least in part, the lack of induction of DNA adducts.

Journal Article↗
PubMed1999

CA-125 tumor-associated antigen in a patient with tuberculous peritonitis.

A 64-year-old woman with a history of chronic hepatitis B had abdominal pain and ascites, a serum albumin ascitic gradient (SAAG) of 0.8, and an elevated serum CA-125 value. Exploratory laparotomy revealed ascites and obliteration of the abdominal cavity by advanced adhesive disease consistent with carcinomatosis. Surgical biopsy revealed noncaseating granulomas. She responded well to antituberculous therapy and is presently asymptomatic.

Ascites↗
PubMed1998

Health education in television entertainment--Medisch Centrum West: a Dutch drama serial.

World-wide a number of groups have sought ways to incorporate health messages into television entertainment like popular drama and soap serials. In the Netherlands, the Heart Foundation incorporated its cardiovascular health message in several episodes of a popular Dutch hospital serial called Medisch Centrum West. To obtain greater insight into the impact of this so-called 'entertainment-education (E & E) strategy', an evaluation study was carried out. Medisch Centrum West was both entertaining and informative at the same time. Although viewers were well aware that the programme included a health message, they did not find it intrusive to their enjoyment of the storyline. It was interesting to learn that fans were more tolerant and positive towards the E & E strategy than non-fans. Age, sex and education level explained only 5% of the variance.

Adolescent↗
PubMed1998

Lymphadenopathy in celiac sprue, not necessarily a malignant disease.

A 47-year-old woman who was studied for other reasons proved to have abdominal lymphadenopathy, some nodes measuring up to 2 cm. The patient, through biopsy and other studies, was diagnosed with celiac sprue; however, on a gluten-free diet, abdominal computed tomography scans several months later showed marked reduction in the size of the mesenteric nodes.

Abdomen↗
PubMed1997

c-Jun NH2-terminal kinase regulation of the apoptotic response of small cell lung cancer cells to ultraviolet radiation.

Exposure of cultured small cell lung cancer (SCLC) cells to UV radiation induces apoptosis. We observed that the UV sensitivity of a panel of SCLC lines and the activation of c-Jun NH2-terminal kinases (JNKs) by UV in the individual SCLC lines, assessed by binding and phosphorylation of glutathione S-transferase (GST)-c-Jun fusion proteins, ranged widely. In fact, increased JNK activity in this assay was closely correlated with decreased sensitivity to apoptosis following UV irradiation. Increased JNK activity was also detected in anti-JNK1 immune complexes collected from UV-irradiated SCLC cells, although the level of activity was similar among the various SCLC lines and correlated poorly with UV sensitivity. Immunoblot analysis of JNK polypeptides that bound to GST-c-Jun revealed at least two JNK polypeptides, one of which appeared only in extracts from UV-irradiated SCLC. To test the role of JNKs in UV-induced apoptosis, nonphosphorylatable mutants of JNK1 or JNK2 in which the phosphorylation site Thr-Pro-Tyr is changed to Ala-Pro-Phe (JNK-APF) and are predicted to behave as competitive inhibitors were stably expressed in SCLC. Expression of JNK1-APF or JNK2-APF significantly reduced UV-stimulated JNK activity. However, JNK1-APF markedly increased the resistance of the cells to UV-induced apoptosis, while JNK2-APF did not influence SCLC sensitivity to UV. The findings suggest that UV-stimulated JNK1 activation promotes UV-induced SCLC apoptosis, while a JNK isoform that is variably activated among the SCLC lines may signal a UV-protective response. We hypothesize that integration of distinct JNK activities dictates the relative responsiveness of SCLC to UV and ionizing radiation.

Apoptosis↗
PubMed1988

Spontaneous noncardiac chest pain. Evaluation by 24-hour ambulatory esophageal motility and pH monitoring.

Noncardiac chest pain can be a diagnostic dilemma because patients rarely experience spontaneous chest pain in the laboratory. Therefore, we studied 24 patients with chronic, daily, substernal chest pain with a prototype 24-h ambulatory esophageal motility and pH system. Spontaneous chest pain episodes were correlated with pH less than 4 and abnormal motility changes (mean amplitude and duration, maximum amplitude and duration, or percentage of abnormal peristalsis) defined as exceeding the patient's normal esophageal motility pattern. Twenty-two patients experienced a total of 92 spontaneous chest pain episodes. Eleven chest pain episodes (12%) occurred during abnormal motility, whereas 18 episodes (20%) were associated with pH less than 4 and four episodes (4%) had both abnormalities. The majority of chest pain episodes, 59 events (64%), did not have any association with motility or pH. Abnormal maximum duration and amplitude were the motility changes most frequently associated with chest pain. Overall, 13 of 22 patients (59%) had at least one chest pain episode correlating with abnormal motility or pH (range 33%-100%). Therefore, we conclude that ambulatory esophageal motility and pH monitoring is useful in the evaluation of noncardiac chest pain. pH abnormalities (20%) are more commonly associated with chest pain than motility abnormalities (12%). However, the majority of chest pain episodes (64%) did not correlate with either abnormality and may be the result of lowered esophageal pain threshold for distention, i.e., the "irritable esophagus."

Chest Pain↗