Cyclic GMP may potentiate lordosis behaviour by progesterone receptor activation

The purpose of this study was to test the hypothesis that cGMP acts as a progesterone substitute to facilitate lordosis in oestrogen-primed rats. Female Sprague-Dawley rats underwent stereotaxic surgery to place a 26-gauge guide cannula into the third ventricle. Bilateral ovariectomy was done at the same time as stereotaxic surgery. Five days later ovariectomized rats were primed with 2 microg estradiol benzoate 24 and 48 h prior to behaviour testing. Some animals were further injected with 200 microg progesterone 4 h before behaviour testing. A nitric oxide synthase inhibitor infused into the third ventricle before progesterone administration significantly reduced lordosis performance. 8-Bromo-cGMP, a cell permeable cGMP analogue, or saline vehicle was infused into the third ventricle of hormone-primed animals approximately 4 h prior to the first of 3-h behaviour tests. This cGMP analogue facilitated lordosis behaviour. We next used KT5823, a highly specific inhibitor of protein kinase G (PKG), to test the hypothesis that cGMP action is mediated by this kinase. In this experiment, KT5823 was infused 15 min before progesterone. KT5823 significantly decreased lordosis behaviour. RU486, a progesterone receptor antagonist, was used to assess whether the stimulatory effects of cGMP are mediated through the progesterone receptor. Oestrogen-primed animals were injected with 5 mg of RU486 or vehicle 60 min before infusion with 8-bromo-cGMP. RU486 significantly attenuated cGMP-facilitated lordosis behaviour. These data show that cGMP facilitates lordosis through activation of PKG and the progesterone receptor.     

正常眼共焦扫描激光多普勒视网膜血流图

目的　探讨共焦扫描激光多普勒视网膜血流图的临床应用价值。方法　应用Ｈｅｉｄｅｌｂｅｒｇ共焦扫描激光多普勒视网膜血流图仪对４８ 例（８２ 只正常眼）视乳头及视网膜血流灌注进行检测。结果　视乳头大血管血流量为２０３１４ ±７４７７,血流速为６ ２７２４３ ±２ ２６００７ ,红细胞移动速率为１３１４ ±２５８ ;视乳头筛板处的血流量为２６３６ ±１４７４ ,血流速为４６７９９ ±２７０１５ ,红细胞移动速率为１９３ ±１０７ 。颞侧视乳头盘沿的血流量为２２９０ ±１１３２,血流速为５１４５３ ±３７０２１,红细胞移动速率为１６９±１１２ ;鼻侧视乳头盘沿的血流量为２１７７ ±９８３,血流速为４９３２１ ±２９０２９,红细胞移动速率为１６５±０９０;颞侧与鼻侧比较差异无显著性（ｔ 值分别为０６８２ ５ ,０４１０ ４,０２５０ １,Ｐ＞ ００５） 。颞侧视乳头旁视网膜的血流量为３２５５ ±１３００,血流速为５５８６３ ±２９３４５ ,红细胞移动速率为１７８ ±０８３;鼻侧视乳头旁视网膜的血流量为２０６１ ±８９２ ,血流速为３５８６４ ±２１２６６ ,红细胞移动速率为１２     

Environmental controls on stomatal conductance in a shrub of the humid tropics

Leaves of Piper hispidum, a shrub native to the lowland tropics of Mexico, have a strong stomatal response to humidity that results in similar rates of water loss under a wide range of leaf-to-air water-vapor concentration gradients. Stomatal conductance of these leaves is insensitive to CO₂ concentration and increases in response to high humidity even in the dark.     

Hybrid Pharmacokinetic Models to Describe Anti-HIV Nucleoside Brain Disposition Following Parent and Prodrug Administration in Mice

Brain delivery of active anti-HIV compounds is important for successful treatment of the AIDS patient. As an initial step in predicting human brain drug concentrations, hybrid pharmacokinetic models were developed to characterize the disposition of anti-HIV nucleosides following parent and prodrug administrations in mice. Mouse data were obtained following intravenous administration of 3-azido-2,3-dideoxyuridine (AZddU or AZDU), 3-azido-3-deoxythymidine (AZT), and their dihydropyridine prodrugs (AZddU-DHP and AZT-DHP). Exponential equations were fitted to the serum concentration–time data for each species, including the pyridinium ion moieties, and subsequently used in differential mass balance equations describing the brain dynamics of each compound. Model parameters for the mass balance equations were estimated by various techniques, including the utilization of in vitro data. In general, model-predicted brain concentrations agreed with the observed data. Similar data in larger animals will permit scale-up of the current model to predict human brain drug concentrations.     

Implications of birth cohort patterns in interpreting trends in breast cancer rates.

BACKGROUND: Most investigations of trends in cancer rates are based on a cross-sectional approach, i.e., an examination of trends in rates by year of diagnosis or death. When there are longitudinal effects (i.e., trends in rates with successive birth cohorts), interpretation of cross-sectional trends can be misleading. Based on cross-sectional comparisons, U.S. breast cancer mortality rates have been reported to be decreasing over the last 20 years in younger women but to be increasing during the same period in older women. PURPOSE: To examine the impact of longitudinal effects on the divergence of cross-sectional trends in breast cancer mortality with age, we examined breast cancer mortality rates from 1969 to 1988 by birth cohort for White women in the United States. METHODS: By using a novel, nonparametric, permutational method to analyze 2-year, age-specific mortality rates for women aged 30-89 years, we identified trends in rates with successive birth cohorts. RESULTS: The divergence in trends with age is shown to be consistent with an increase in breast cancer risk with successive birth cohorts from 1900 to 1916 and with a decrease in breast cancer risk with successive birth cohorts beginning around 1926. CONCLUSION: Longitudinal effects have a significant impact on cross-sectional trends in breast cancer mortality. IMPLICATIONS: Continuation of the birth cohort trend in younger women, which could correspond to changes in reproductive patterns accompanying the "baby boom," would result in decreasing cross-sectional trends in women 60-69 years of age over the next decade and in women 70-79 years of age in the subsequent decade. Longitudinal effects must be taken into consideration when monitoring and evaluating the effects of early detection, treatment, and intervention programs using national rates.     

Side effects during continuous epidural infusion of morphine and fentanyl

Respiratory effects, nausea, somnolence, and pruritus were compared during a 48-hr period of continuous epidural morphine (n = 34) and fentanyl (n = 32) infusion in 66 patients following elective total replacement of the hip or knee joint. Respiratory effects were assessed by PaCO2. Side effects were assessed by visual analogue scale and considered to be present when the score was above 30. Assessment was made at preoperative visits then 3, 6, 12, 24, 36, and 48 hr after the epidural injection. The bolus dose and subsequent infusion rate were 3,900 +/- 1,300 micrograms and 427 +/- 213 micrograms.hr-1 for morphine, and 85 +/- 46 micrograms and 56 +/- 27 micrograms.hr-1 for fentanyl. Pain relief was similar in both groups. In the morphine group, PaCO2 elevation and nausea occurred over a period of more than 12 hr (P less than 0.05). In the fentanyl group, there was no PaCO2 change, and nausea was confined to the first few hours. Nausea was more severe (P less than 0.01 at six hours and more frequent (24 hr cumulative incidence, 53 vs 28%, P less than 0.05) in the morphine group. Somnolence was prominent within several hours in two-thirds of patients in both groups. Somnolence continued to decline thereafter in the morphine group, but it was demonstrable in approximately half of the patients throughout the second day in the fentanyl group. The incidence was higher in the fentanyl group at the 48th hr (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Statistical issues in interpretation of chronic bioassay tests for carcinogenicity.

The interpretation of chronic bioassay tests for carcinogenicity requires that the data be appropriately recorded. A "case history" for each animal links the pathology data for each organ of each animal to the length of its life. This information can be used in interpretation of the tumor incidences in light of the survival information. The role of historical controls was discussed, and the use of significance tests in a multidisciplinary approach to the assessment of the pattern of tumor response was suggested. Multiple comparison methods valid for the interpretation of continuous (or measurement) data do not apply to the discrete data analyses used in these studies. The ideas and methods of these studies were applied to an animal study of chloroform.     

Clinical characteristics of patients with thyrotropin-secreting pituitary adenoma.

BACKGROUND AND PURPOSE: Thyroid-stimulating hormone (thyrotropin, TSH)-secreting pituitary adenoma is a very rare cause of hyperthyroidism. Diagnosis of this condition is often delayed due to lack of availability of TSH radioimmunoassay (RIA), the failure to recognize the utility of RIA and the incorrect attribution of the condition to other causes of thyrotoxicosis. This retrospective study analyzed the clinical characteristics of patients with this disorder treated from 1991 to 2002. METHODS: Seven patients (6 females, 1 male; mean age, 48 years; range, 33 to 72 years) with a diagnosis of TSHsecreting pituitary adenoma based on detectable TSH levels with high serum free thyroid hormone or triiodothyronine concentrations and pituitary lesions found on neuroimaging were included in this study. Patient records including clinical features, endocrine studies, immunohistochemistry studies, and response to treatment were reviewed. RESULTS: All 7 patients had hyperthyroidism, elevated free thyroxine or triiodothyronine levels, and unsuppressed levels of TSH. Imaging studies demonstrated a pituitary mass or lesion in all patients. Six patients had macroadenomas and 1 patient had a microadenoma. One of the patients had coexisting acromegalic features and hypersecretion of growth hormone was diagnosed. All of the patients had been treated with thionamides or thyroidectomy for presumed primary hyperthyroidism. Serum alpha-subunit level was uncharacteristically normal in 2 patients and elevated in 1 patient. Alpha-subunit/TSH molar ratios were elevated in 3 patients. Five patients underwent transsphenoidal adenomectomy but only one of them remained well-controlled at follow-up. Three patients received administration of somatostatin analogs and they achieved normalization of serum TSH and free thyroid hormones during the period of therapy. CONCLUSIONS: TSH immunoassay has an important role in the evaluation of hyperthyroid patients to determine the presence of inappropriate secretion. TSH-secreting pituitary adenoma exhibits heterogeneity in clinical presentation, hormonal expression and therapeutic response.