Overexpression of corticotropin-releasing hormone in transgenic mice and chronic stress-like autonomic and physiological alterations

To gain a greater insight into the relationship between hyperactivity of the corticotropin-releasing hormone (CRH) system and autonomic and physiological changes associated with chronic stress, we developed a transgenic mouse model of central CRH overproduction. The extent of central and peripheral CRH overexpression, and the amount of bioactive CRH in the hypothalamus were determined in two lines of CRH-overexpressing (CRH-OE) mice. Furthermore, 24 h patterns of body temperature, heart rate, and activity were assessed using radiotelemetry, as well as cumulative water and food consumption and body weight gain over a 7-day period. CRH-OE mice showed increased amounts of CRH peptide and mRNA only in the central nervous system. Despite the presence of the same CRH transgene in their genome, only in one of the two established lines of CRH-OE mice (line 2122, but not 2123) was overexpression of CRH associated with increased levels of bioactive CRH in the hypothalamus, increased body temperature and heart rate (predominantly during the light (inactive) phase of the diurnal cycle), decreased heart rate variability during the dark (active) phase, and increased food and water consumption, when compared with littermate wildtype mice. Because line 2122 of the CRH transgenic mice showed chronic stress-like neuroendocrine and autonomic changes, these mice appear to represent a valid animal model for chronic stress and might be valuable in the research on the consequences of CRH excess in situations of chronic stress.     

Human papillomavirus 16 load in normal and abnormal cervical scrapes: an indicator of CIN II/III and viral clearance

The relation between human papillomavirus type 16 (HPV 16) viral load in cervical scrapes and development of high-grade cervical intraepithelial neoplasia (CIN II or III) was studied in a nested case-control study of women with normal cytology (group A) and in a cohort of women with abnormal cytology (group B). HPV 16 DNA load was determined using a quantitative real-time PCR assay. In group A, case women (women with CIN II/III, n = 12) had a significantly higher viral load than control women (women with CIN < or = I, n = 47). This resulted in an increased relative risk of women with the 50% highest viral load for development of CIN II/III (OR 7.7; CI 1.6-33). In group B, women with CIN II/III (n = 38) had a significantly higher viral load than women with CIN < or = I (n = 25). Women with the 50% highest viral load had an increased relative risk of CIN II/III (OR 3.2; CI 1.1-9.3) and a decreased chance of both viral clearance and cytologic regression. Our data suggest that in women with normal cytology an increased HPV 16 load confers an increased risk of developing a CIN lesion. A sustained high viral load is subsequently informative for progression to a high-grade CIN lesion.     

Pharmacokinetics of the antitumor antibiotic n-pentyl-sparsomycin in beagle dogs

Summary N-pentyl-sparsomycin (PSm) is a lipophilic analogue of sparsomycin (Sm), which is a well known inhibitor of protein synthesis. This compound was selected for preclinical pharmacokinetic studies because of its high in vitro and in vivo antitumor activity. In this study in which the drug was evaluated in beagle dogs under anaesthesia, the drug concentrations in plasma, urine and bile samples were determined using high performance liquid chromatography (HPLC). Plasma protein binding was approximately 54%. The mean t1/2 was 0.2 hours (12 minutes) and t1/2 was 0.75 ± 0.1 hours (45 ± 6 minutes). During continuous infusions up to 5.25 hours, the steady state was reached in 3 out of 6 experiments, suggesting that in some cases the real t1/2 was longer than measured. PSm was actively reabsorbed from the renal tubuli. This process was saturable at the higher doses. Tubular reabsorption played only a minor role in pharmacokinetics as most of the drug (67%) was eliminated by the non-renal clearance. The non-renal clearance was saturable at higher doses of PSm and was the reason for non-linearity of pharmacokinetics.     

Quality control of estrogen receptor assays in the Netherlands

Summary Lyophilized receptor-positive tissue powders and cytosols, prepared from calf uterus and human breast tumor tissue, are used to assess the validity of routine dextran-coated charcoal estrogen receptor assays. Since 1978 lyophilized reference preparations have been analyzed twice yearly by 18 laboratories in the Netherlands. During 8 consecutive trials 20 different lyophilized samples were studied. The inter-laboratory variability of estrogen receptor results decreased with time. Most laboratories found receptor values around the median value of all groups together, though some participants consistently reported estrogen receptor values that were higher or lower than the median. The variability of estrogen receptor results between labs seemed to be associated with cytosol dilution, determination of non-specific binding, concentration and volume of dextrancoated charcoal, and the use of single dose assays or Scatchard analysis. The agreement on the presence or absence of estrogen receptors was more than 98% for lyophilized reference samples with high receptor content. For samples with low receptor content 85% agreement was observed, while 12% of the assays performed on receptor-negative material were reported to be estrogen receptor-positive. The use of the same protein determination (Coomassie Brilliant Blue) and human serum albumin standard has decreased the interlaboratory variation coefficient of the protein results to 7.5%. Address for reprnts: A. Koenders, Dept. of Experimental and Chemical Endocrinology, St. Radboud Hospital, Geert Grooteplein Z 8, 6500 HB Nijmegen, the Netherlands List of participating laboratories and institutions: Hospital de Lichtenberg, Amersfoort; Antoni van Leeuwenhoek Hospital, Amsterdam; Foundation Medical Laboratories, Breda; Foundation of Cooperative Hospitals Delft (SSDZ), Delft; Catharina Hospital, Eindhoven; Hospital de Stadsmaten and Ziekenzorg, Enschede; Academic Hospital, Groningen; The Wever Hospital, Heerlen; Laboratory of Public Health, Leeuwarden; Department of Pathological Chemistry, Academic Hospital, Leiden; Department of Experimental and Chemical Endocrinology, Sint Radboud Hospital, Nijmegen; Scientific Development Group Organon International B.V., Oss; Department of Biochemistry II, Erasmus University Rotterdam, Rotterdam; Rotterdam Radio-Therapeutic Institute/ Dr Daniel den Hoed Clinic, Rotterdam; Institute of Oncology Dr Bernard Verbeeten, Tilburg; Department of Endocrinology, Academic Hospital, Utrecht; Laboratory for Nuclear Medicine Voorburg, Vught; Sophia Hospital, Zwolle.     

Carbon-11 labelled tyrosine to study tumor metabolism by positron emission tomography (PET)

To measure the rate of protein synthesis in human neoplasms by positron emission tomography, we prepared no carrier added DL-(1-¹¹C)-tyrosine by ¹¹C-carboxylation of the appropriate -lithioisocyanide followed by hydrolysis of the isocyanide function and removal of the protecting methoxy group. The purification, resolution and solvent switch to saline was performed by high performance liquid chromatography (HPLC). DL-(1-¹¹C)-Tyrosine in 0.1 N NaH₂PO₄ buffer was prepared with a radiochemical yield of 8%–16% (EOS, 35 min). The enantiomeric separation and solvent switch to saline were achieved in 5 min and 10 min respectively. Consequently L-(1-¹¹C)-tyrosine in physiological saline was obtained in 2%–4% radiochemical yield. Tumor accumulation in rats with the experimental WALKER 256 carcinosarcoma was observed for both the L- and D-isomer. Using positron emission tomography a tumor/muscle ratio of two was observed for the L-isomer 15 min after injection. The corresponding figure for the D-isomer was 2.5. The first clinical results with DL-(1-¹¹C)-tyrosine show accumulation of radioactivity in meningioma, a primary breast carcinoma and in liver metastases of a colonic carcinoma.     

Relationship between habitual refractive errors and headache complaints in schoolchildren.

PURPOSE: Refractive error (RE) is considered to be a possible cause for headaches. We aimed to gain insight into the relation between habitual RE (sphere and astigmatism) and headache complaints. METHODS: In a cross-sectional study the habitual refractive state of 487 children, aged between 11 and 13 years, was measured using an autorefractometer (Topcon, RM-8000B). Headache complaints were measured using a questionnaire. Data were analyzed using Pearson correlation coefficients, bivariate analysis, and multiple logistic regression analysis. RESULTS: For right eyes we found 15% habitual myopia < -0.50 D and 12% habitual hyperopia > +0.50 D; habitual astigmatism > 0.25 D was found in 33% of children. Pearson R between right and left eyes was 0.76 for the spherical component and 0.42 for the cylindrical. In the total group of children 70% reported the occurrence of headache in the last year. These headaches were reported as "often or frequent" by 37% of children, "severe" by 15%, "with long duration" by 45%, and "with severe burden" by 27%. In the total sample we found various associations between gender, sphere/cylinder components of habitual RE, and headache complaints. Headache was reported more in girls than in boys. Of the total variance of headache complaints in girls, the sphere component of habitual RE explained 4% of frequency, 6% of intensity, 2% of duration, and 2% of amount of burden. Of the total variance of headache complaints in boys the cylinder component of habitual RE explained 3% of frequency, and 4% in amount of burden. CONCLUSION: Habitual RE and headache complaints are relatively common conditions in schoolchildren aged between 11 and 13 years. Headache complaints showed a small but statistically significant association with the sphere component of habitual RE in girls and the cylinder component of habitual RE in boys. The associations found between habitual RE and headache complaints indicate that habitual RE might be a risk factor for headache in children.     

A retrospective analysis of the added value of the rat two-generation reproductive toxicity study versus the rat subchronic toxicity study

This study aims to evaluate the added value of the two-generation reproductive toxicity study when a subchronic study (90-day repeated dose toxicity study) is available. The analysis includes a total of 47 reproductive toxic and 75 non-reproductive toxic substances, for which a two-generation study was available. For each of these compounds the outcomes of both study types were compared, in view of the question what the impact would have been both for the derived NOAEL and for classification regarding toxicity to fertility. On average, only a small difference (less than twofold) in overall NOAELs was found between the rat two-generation study and the rat subchronic study. For individual compounds the differences could be larger (up to around a factor of 10), but differences of this magnitude equally occur between NOAELs of subchronic studies (testing the same substance). The two generation study did have an impact on classification for toxicity to fertility: about one-third of the substances shown to be toxic to fertility in the two-generation study did not show any sign of that in the 90-day study. If the subchronic study did show toxicity to reproductive organs this often occurred at (much) higher doses than other toxic effects in the same study. Therefore, apart from including more fertility endpoints, a larger dose spacing (or more dose groups) in the subchronic study might increase its detection rate of fertility toxic substances. The consequences that these findings may have for risk assessment and risk management are discussed, especially in the context of REACH.     

Are patient characteristics helpful in recognizing mild COPD (GOLD I) in daily practice?

OBJECTIVE: To determine whether in a high-risk group of middle-aged male current smokers, patient characteristics are useful to recognize mild COPD (GOLD stage I). DESIGN: In a cross-sectional study spirometry was performed according to the American Thoracic Society criteria. COPD was defined according to the GOLD criteria for COPD. SETTING: Primary care. SUBJECTS: Male smokers, aged 40-65 years, without documented lung disease in the population at large. MAIN OUTCOME MEASURES: Medical records were scrutinized to collect patient characteristics. Multiple logistic regression analysis was used to identify independent determinants of mild COPD. RESULTS: A total of 567 subjects participated. COPD, defined by a FEV1/FVC ratio < 0.7, was detected in 170 subjects (30.0%, 95% CI 26.2-33.9%). In 149 subjects (26.3%; 22.7-30.1%) COPD was mild (GOLD stage I) and in 21 subjects (3.7%; 2.3-5.6%) moderate (GOLD stage II). Only age and cough were independently associated with the presence of mild COPD. The ability of these determinants to discriminate between subjects with or without mild COPD was relatively poor (ROC area 0.65). Therefore no prediction rule was developed. CONCLUSION: Our results indicate that patient characteristics are not helpful to recognize mild COPD (GOLD stage I) in middle-aged male smokers.