Evidence that oxytocin is a physiological component of LH regulation in non-pregnant women

BACKGROUND: Regulation of the LH surge is central to the functioning of the female ovulatory cycle. In animal models, oxytocin has been shown to alter LH activity. Oxytocin advanced the LH surge and, conversely, oxytocin receptor antagonists inhibited full production of the LH surge in rats. Few data exist on the possibility that oxytocin modulates LH in women. METHODS: Ten non-pregnant women participated in this study over two menstrual cycles. One cycle was a control cycle, and the other a trial cycle; the two were separated by at least one cycle. When the diameter of an ovarian follicle was >15 mm, a subject was allocated at random into either a control or treatment group. In a control cycle, volunteers received normal saline; in a treatment cycle, volunteers received an oxytocin antagonist (atosiban). RESULTS: For treatment cycles, the maximum LH concentration was significantly less than that in control cycles (42.1 +/- 6.2 versus 60.3 +/- 8.3 IU/l respectively; P < 0.05). Maximum FSH and estradiol concentrations were not significantly different between the two groups. CONCLUSIONS: The results indicated that inhibition of endogenous oxytocin affects the endocrinology of the ovulatory cycle in women, and strongly suggest that oxytocin has a role in the physiological processes of LH regulation.     

Second malignancies in early stage laryngeal carcinoma patients treated with radiotherapy

A retrospective review of 240 patients with T1/T2 squamous cell carcinomas of the larynx was performed. Seventy-two per cent had glottic primaries, 27 per cent had supraglottic tumours and one per cent had subglottic disease. Sixty-nine per cent presented with T1 disease and 31 per cent had T2 staged tumours. All patients were treated with definitive radiotherapy between 1973 and 1997. With a median follow-up of 68 months, 68 patients (28 per cent) have developed 72 other cancers. Ten of 68 presented with synchronous primaries (15 per cent). Thirty per cent of glottic patients and 25 per cent of the supraglottic/subglottic patients developed second cancers. The most frequent second malignancy was lung cancer: 28/72 (39 per cent). Fifteen patients developed second head and neck cancers (21 per cent). Other second primary sites included oesophagus (eight), prostate (six), colorectal (five), breast (two) and others (eight). The median time from radiotherapy until the development of a second cancer was 31 months. The Kaplan-Meier survival estimate at five years was significantly less for those patients developing second cancers (55 per cent) compared to those not developing second malignancies (70 per cent), (p<0.05). The median survival from the development of a second cancer was 14 months. More died as a result of a second cancer (41 patients) than their primary laryngeal cancer (40 patients). Second cancers are common and deadly in patients with early stage laryngeal carcinoma.     

Sorption of phenanthrene and atrazine by plant cuticular fractions

Several studies have shown selective preservation of plant cuticular materials in soils. However, very little is known about their function as sorbents for the hydrophobic organic contaminants (HOCs) in the soil. In this study, we investigated the sorption and desorption of phenanthrene and atrazine by cuticular fractions of pepper (bulk, dewaxed, nonsaponifiable, and nonhydrolyzable) to better understand the sorptive activity of cuticular matter in soils. The bulk and dewaxed cuticles exhibited carbon-normalized distribution coefficients (Koc) for phenanthrene and atrazine in the range of that reported for soil humic substances, although both samples were rich in aliphatic structures. No hysteresis was observed in the desorption isotherms of either solute. The nonhydrolyzable residue exhibited a very high Koc value for atrazine, whereas the nonsaponifiable sample be exhibited the lowest Koc value for both sorbates. Based on solubility parameter data, it is suggested that the nonsponifiable sample be considered an intermediate between the physical and chemical mixture of pectin and cutan/lignin-like fractions, whereas the dewaxed cuticle is a chemical blending of cutin and pectin. The n-hexane-normalized sorption data suggest that the pepper cuticle can interact specifically with atrazine. This study leads to the conclusion that the contribution of aliphatic-rich plant biopolymers to the sorption of HOCs can be significant because of their preservation and accumulation in soils.     

An inter- and intra-laboratory comparison of breath ¹³CO₂analysis

BACKGROUND: 13C breath test analysis requires accurate 13CO2 measurements. AIM:: To perform a multicentre study to evaluate the repeatability and reproducibility of breath 13CO2 analysis. METHODS: Two series of 25 paired randomly coded tubes (each consisting of 23 13CO2-enriched breath samples and two samples of standard reference pure CO2 with certified delta 13CPDB) were sent to participating centres for 13CO2 measurement. Each series of tubes was analysed 10 days apart. The repeatability and reproducibility of 13C measurements was assessed by Mandel's k and h statistics. RESULTS: Twenty-two centres participated in the study: 18 showed good inter- and intra-laboratory variability, whilst four showed abnormally high inter- or intra-laboratory variability. Breath test results were also significantly affected by the accuracy of the 13C analytical procedures. CONCLUSIONS: A low accuracy of 13C measurements may significantly affect the results of breath tests, leading to inappropriate clinical decisions. Standardization of 13C analysis is required to guarantee optimal 13C measurements and accurate 13C breath test results.     

Relationship between anti-oxidant activities and doxorubicin-induced lipid peroxidation in P388 tumour cells and heart and liver in mice

1. The present study found that, compared with mouse heart and liver, P388 ascitic tumour had significantly lower superoxide dismutase (SOD) activity and that compared with the mouse liver, the heart had significantly lower SOD and catalase activities, as well as a lower glutathione content. 2. At 7.5 mg/kg, doxorubicin (DOX), a superoxide radical inducer, induced significant lipid peroxidation only in the tumour, whereas 15.0 mg/kg DOX induced lipid peroxidation in both the tumour and heart, but not in the liver. 3. Overall, the results of the present study suggest that the differential anti-oxidant activities in P388 ascitic tumour, heart and liver in mice may explain their differential responses and, hence, susceptibility to DOX-induced lipid peroxidation.     

Functional determination of C1 esterase inhibitor in fractions derived from plasma

A traditional esterolytic assay, a commercial chromogenic assay and an in-house chromogenic assay were compared for suitability in estimating C 1 esterase inhibitor (C 1 INH) activity in plasma and fractions obtained during preparation of a clinical concentrate of C 1 INH. The esterolytic and both of the chromogenic assays showed similar C 1 INH activity in unfractionated plasma samples. However, the esterolytic assay was significantly influenced by the buffer pH and concentration in fractionated plasma samples, and this often resulted in a significant overestimation of C 1 INH in some fractions. Similarly, the commercial C 1 INH assay kit did not always reliably estimate C 1 INH activity in fractions derived from plasma. A modified in-house functional assay was found to be more reliable in measuring C 1 INH in fractionated plasma samples. There was a good correlation between this activity assay and immunological assay estimates of C 1 INH in fractions derived from plasma.