UV-absorbing compounds and waxes of Scots pine needles during a third growing season of supplemental UV-B.

Methanol-extractable UV-absorbing compounds, wax tube distribution and the chloroform-soluble waxes of the needles of mature Scots pines were studied in a UV-B field experiment in Oulu (65 degrees N). Throughout the experiment, UV-B lamp banks were placed over the same selected branch and each year needle samples were taken from the same branch. In the third exposure year, needle samples were taken twice a month from 3-day-old needles (18 June) to fully developed needles (13 August). On 28 September, the previous year's needles (c + 1, c + 2) were also collected. There was a significant negative correlation between the amount of waxes and UV-absorbing compounds. A high amount of UV-absorbing compounds was observed early and late in the season when the amount of waxes was low and epicuticular waxes were undeveloped (youngest needles) or already eroded (c + 2 needles). The amount of UV-absorbing compounds (A310/cm2 and A320/cm2) was significantly (30-day-old needles) or slightly (all the other needle ages) higher in the ambient needles compared to the needles under supplemental UV-B. This possibly indicated the already inhibited pigment synthesis in the UV-B-treated needles during the third year of supplemental UV-B. This observation could mean that the protective mechanisms may not be effective under accumulated UV-B dose.

The glutathione status of mature Scots pines during the third season of UV-B radiation exposure.

Impacts of UV-B radiation on the glutathione level were studied in mature Scots pine needles (Pinus sylvestris L.) during the third season of a UV-B field experiment. Studies were made on 4-week-old (July) to 14-week-old (September) current-year needles and 3-year-old needles which had their third UV-B-exposure season in progress. Depending on the season and the year (1996-98), the supplemental UV-B dose varied from 0.92 to 5.09 kJ m-2 day-1 UV-BBE compared to 0.47-2.44 kJ m-2 day-1 UV-BBE under the ambient treatment. Fully grown UV-B-treated current-year needles showed lower total glutathione concentrations after the vegetation period in September, whereas in UV-B-treated 3-year-old needles the total glutathione content was significantly lower and the proportion of oxidized glutathione (GSSG%) 56% higher in July. The significant differences in total glutathione in current-year needles in September and in active 3-year-old needles in July seem to indicate that the effect of enhanced UV-B radiation on glutathione status could be cumulative.

The long form of the leptin receptor (OB-Rb) is widely expressed in the human brain.

Leptin exerts important effects on the regulation of food intake and energy expenditure by acting in the brain. Leptin action is mediated by the interaction with a receptor that is alternatively spliced, resulting in at least five different isoforms. The long form (OB-Rb) has a long intracellular domain that is essential for intracellular signal transduction. The specific aim of this study was to further investigate the role that the brain may play in the pathogenesis of obesity in humans. We studied the expression of OB-R mRNA (both short or common and long isoforms) in the brains of obese, lean and diabetic subjects, by in situ hybridization, semiquantitative RT-PCR and Northern blots analysis. We used two alternative probes: one that recognizes all known splice variants (OB-Ra) and a second that recognizes only the long form, OB-Rb. Several brain regions, including hypothalamus, cerebellum, neocortex, entorrhinal cortex, amygdala, and rostral medulla, were evaluated. In situ hybridization studies revealed that both OB-Ra and OB-Rb mRNAs are widely distributed in the human brain. The specific hybridization signal with both probes was detected exclusively in the cytoplasm of the cell body, dendrites and proximal axons of neurons. Hypothalamic nuclei, Purkinje cells and dentate nuclei of the cerebellum, inferior olivary and cranial nerves nuclei in the medulla, amygdala and neurons from both neocortex and entorrhinal cortex demonstrated positive signals. The hybridization signal obtained in ependyma was lower than that in neurons and no specific hybridization was detected in glial cells. No significant differences were identified among the regions or among the three groups studied. These results match those previously obtained by us [Couce et al.: Neuroendocrinology 1997;66:145] in which the distribution of the OB-R protein in the human brain was first described. RT-PCR indicated that the OB-Rb was highly expressed in the hypothalamus and cerebellum. No significant differences of OB-Ra or OB-Rb mRNA expression were identified in lean or obese individuals in these two cerebral regions. The levels of OB-Rb were significantly higher in cerebellum compared to hypothalamus in lean and obese individuals. The original hypothesis that OB-Rb is present only in the hypothalamus needs to be reconsidered. This OB-Rb isoform seems to be widely expressed in the human brain with highest levels in the cerebellum. Obesity and hyperleptinemia appears not to be associated with down-regulation of the OB-Rb in the human brain.

Characterization and growth regulation of a rat intrahepatic bile duct epithelial cell line under hormonally defined, serum-free conditions.

Bile duct epithelial cells, or cholangiocytes, proliferate in vivo under a number of pathologic (i.e., partial hepatectomy) and pathophysiologic (i.e., bile duct ligation, malignant transformation) conditions. However, little is known about the possible growth factors that modulate these proliferative responses, in part because an in vitro model to study proliferation of nontransformed, normal cholangiocytes is not available. We report here the development of a rat cholangiocyte cell line (MMRC, minimal media-requiring rat cholangiocytes) that grows under hormonally defined, serum-free conditions on plastic and maintains a cholangiocyte phenotype. Morphologic as well as functional studies indicate that the cell line is polarized and actively transports fluid and electrolytes in an apical to basolateral direction. MMRC, when cultured for 24 mo. and passaged 80 times, have not undergone malignant transformation, because the cell line failed to grow under anchorage-independent conditions or in nude mice. Cellular proliferation is accelerated 2-8-fold by insulin, insulin-like growth factor 1, epidermal growth factor, and hepatocyte growth factor, growth factors known to stimulate tyrosine kinase receptors, and inhibited 2-10-fold by TGFbeta and IL-2. Glyco-conjugates of primary (i.e., cholic and chenodeoxycholic acid) and secondary bile acids (i.e., deoxycholic and lithocholic acid) do not alter proliferation at low concentration (1 microM), but are toxic at higher concentration (10 microM). In summary, we have developed and characterized a cholangiocyte cell line derived from normal rat liver, which grows under hormonally defined, serum-free conditions, maintains a nonmalignant, cholangiocyte phenotype, displays morphologic and functional features of polarity, and alters its proliferation rate in response to a variety of growth factors.

Effects of the ultraviolet-B radiation (UV-B) on conifers: a review.

The current knowledge on conifer responses to enhanced ultraviolet-B (UV-B) radiation is mainly based on greenhouse or growth chamber experiments of one growing season in duration. However, the biomass losses observed in greenhouses do not occur in field-grown trees in their natural habitats. Moreover, the majority of the 20 conifer species studied have been 1-year-old seedlings, and no studies have been undertaken on mature trees. Fully grown needles, with their glaucous waxy surfaces and thick epidermal cells with both soluble and wall-bound UV-B screening metabolites, are well protected against UV-B radiation. However, it is not known whether these are sufficient protectants in young emerging needles or during the early spring period of high UV-B levels reflected from snow. In order to understand all the mechanisms that result in the protection of conifer needles against UV-B radiation, future research should focus on the epidermal layer, separating the waxes, cuticle and epidermal and hypodermal cells. Parallel studies should consist of wall-bound and soluble secondary metabolite analysis, antioxidant measurements and microscopic observations.

Effects of oral contraceptive and estrogen administration on plasma calcitonin in pre- and postmenopausal women.

Estrogen (E) therapy and administration of oral contraceptives (OC) reportedly increase plasma calcitonin (CT) concentrations in women, effects said to mediate in part the beneficial actions of E on bone. To further examine this theory, we tested the effects of three cycles of OC therapy in 12 young women, comparing them to 10 healthy women before and after three normal menstrual cycles. We also determined the effects of 3 months of E therapy (ethinyl estradiol, 20 micrograms/day, 25 of 30 days) in 14 healthy postmenopausal women, using a crossover design (studied after 3 months with and 3 months without E). We determined CT by radioimmunoassay (antiserum G-1701) in whole plasma (iCT) and silica cartridge extracts of plasma (exCT) after overnight fasting, after calcium (Ca) infusion (2 mg Ca/kg over 5 minutes), and during a normal day at 0800, 1200, 1700, and 2000 h. In no control study was there a significant diurnal change in iCT or exCT, and neither OC nor E therapy altered this. Similarly, OC administration did not affect basal CT levels or the normal iCT and exCT responses to Ca infusion. E therapy induced expected changes in serum Ca, phosphorus, and alkaline phosphatase and urinary Ca and cAMP excretion; basal and diurnal plasma exCT levels were decreased significantly, consonant with the decrement in serum Ca. E did not alter normal iCT and exCT responses to Ca infusion. Thus, administration of either OC or E has no stimulatory effect on CT secretion, which suggests that the beneficial actions of E on bone are not mediated through CT-induced inhibition of bone resorption.(ABSTRACT TRUNCATED AT 250 WORDS)

Response to a diet low in total fat in women with postmenopausal breast cancer: a pilot study.

A feasibility study was instituted to determine if women with postmenopausal breast cancer would follow a low-fat diet (20% of kcal) for at least four months. Nineteen women, whose baseline food intake was 1,504 +/- 420 kcal with 56 +/- 16 g of fat, reported a decrease in fat intake to 21 +/- 6 g after two months of dietary intervention. Serum concentrations of cholesterol, HDL cholesterol, and estradiol were significantly reduced by the fifth month on the diet. We conclude that self-selected patients can adhere to a low-fat diet, and that serum cholesterol may serve as an indicator of dietary compliance.

Chemical neurotransmission in the parkinsonian brain.

In Parkinson's disease the progressive loss of nigrostriatal dopamine neurons leads to striatal dopamine deficiency and correlates with the severity of parkinsonian disability. The findings concerning dopamine receptors both in vitro and in vivo are not consistent, possibly reflecting differences in patient populations, but the presynaptic defect in dopaminergic neurotransmission is greater than that seen in postsynaptic receptor binding studies. The cholinergic neurons in the extrapyramidal nuclei are relatively well preserved, but subcortico-cortical and -hippocampal cholinergic neurons degenerate in relation to the degree of dementia. The decreased GABA receptor binding in the parkinsonian substantia nigra possibly reflects the loss of nigral dopamine neurons, since nigral GABA receptors are located on these neurons. Of the various neuropeptides, the concentration of met- and leu-enkephalin seems to be reduced in the striatum. In the substantia nigra the concentration of substance P decreases, together with the met-enkephalin and cholecystokinin levels. The concentration of somatostatin decreases in the frontal cortex and hippocampus of demented patients. With the exception of the association between cortical somatostatin deficiency and intellectual deterioration, the role of the neuropeptides in the pathophysiology and clinical features of Parkinson's disease are not yet fully understood.

Metabolic epidemiology of colon cancer: effect of dietary fiber on fecal mutagens and bile acids in healthy subjects.

Because of potential significance of fecal mutagens and secondary bile acids in the pathogenesis of colonic cancer and of inverse association between dietary fiber and colonic cancer risk, the effect of dietary wheat and rye fiber on fecal mutagenic activity and bile acid levels was studied in 15 healthy men and women who were consuming high fat/moderately low fiber diets and excreting high levels of fecal mutagens and bile acids. Each participant provided two 24-h stool specimens and a 3-day diet record while consuming their normal diet (control). All subjects were then asked to consume their normal diet plus 11 g of supplemental fiber per day in the form of whole grain bread for 4 weeks. During the last week of diet intervention, each subject provided two 24-h stool specimens and a 3-day dietary record. Fecal samples collected from both periods were analyzed for bile acids and for mutagens using Salmonella typhimurium strains TA98 and TA100 with and without microsomal activation. The concentration of fecal secondary bile acids was significantly lower during the fiber supplemental period in all subjects. Fiber supplementation also inhibited the fecal mutagenic activity in TA100 and TA98 with and without microsomal activation. Thus, the increased fiber intake in the form of whole wheat and rye bread may reduce the production and/or excretion of fecal mutagens and decrease the concentration of fecal secondary bile acids in humans.

Serum and breast duct fluid prolactin and estrogen levels in healthy Finnish and American women and patients with fibrocystic disease.

Nipple aspiration yielded measurable amounts of breast duct fluid for 27 of 42 (64%) healthy premenopausal Finnish women, 93 of 218 (43%) premenopausal American patients with fibrocystic disease, but only 24 of 92 (26%) healthy American premenopausal controls. When aspiration was successful, the average volumes obtained were larger for the normal Finnish women and, particularly, for the American fibrocystic disease patients compared with the American controls. The difference in secretion between the healthy Finnish and American women appeared to be related to a history of breast feeding, and its duration. While serum estrogen and prolactin concentrations were similar in the three groups, prolactin levels in breast fluids from the Finnish women were frequently higher than those in the American controls. A similar trend, which did not reach statistical significance, was observed in the 43 of 93 (46%) secretors with fibrocystic disease and cyclical mastalgia.

Dopamine D-1 receptors in the parkinsonian brain.

Dopamine D-1 receptors were analyzed in the caudate nucleus, putamen, pallidum, substantia nigra and nucleus accumbens in 20 patients with Parkinson's disease and in 18 age-matched controls by the binding of [3H]flupenthixol. The binding was decreased in the substantia nigra in those parkinsonian patients who were not treated with levodopa. A significantly increased number of D-1 receptors was found in the putamen of patients with Parkinson's disease, especially in those who were treated with levodopa. The increased binding of [3H]flupenthixol was most prominent in those six parkinsonian patients who still had therapeutic response to levodopa. In addition, orofacial dyskinesias were seen in three of these patients. The results of this study indicate that there may be denervation supersensitivity of striatal neurons and also a loss of striatonigral neurons in Parkinson's disease.

Structural requirements for parathyroid hormone action in mature bone. Effects on release of cyclic adenosine monophosphate and bone gamma-carboxyglutamic acid-containing protein from perfused rat hindquarters.

To determine the structural requirements for parathyroid hormone (PTH) activity in mature bone, we perfused the surgically isolated hindquarters of adult male rats with either native bovine PTH-(1-84) [bPTH-(1-84)] or the synthetic amino-terminal fragment, bovine PTH-(1-34) [bPTH-(1-34)]. Changes in the release of cyclic AMP (cAMP) and bone Gla protein (BGP) were monitored as evidence of bone-specific response to PTH; tissue specificity of the cAMP response was confirmed through in vitro examination on nonskeletal tissue response to PTH. Biologically active, monoiodinated 125I-bPTH-(1-84) was administered to determine if mature murine bone cleaves native hormone. We found that perfused rat bone continuously releases BGP, and that both bPTH-(1-84) and bPTH-(1-34) acutely suppress this release. In addition, both hormones stimulate cAMP release from perfused rat hindquarters. When examined on a molar basis, the magnitude of the cAMP response was dose-dependent and similar for both hormones, with doses yielding half-maximal cAMP responses. The response for bPTH-(1-34) was 0.5 nmol and for bPTH-(1-84) was 0.7 nmol. Moreover, biologically active 125I-bPTH-(1-84) was not metabolized in our hindquarter perfusion system. These findings indicate that PTH-(1-84) does not require extraskeletal or skeletal cleavage to an amino-terminal fragment in order to stimulate cAMP generation in, or suppress BGP release from, mature rat bone.

Metabolic epidemiology of colon cancer: fecal mutagens in healthy subjects from rural Kuopio and urban Helsinki, Finland.

Fecal mutagenic activity and dietary pattern of rural and urban Finnish population groups with distinct risk for the development of colon cancer were studied in a low-risk population in rural Kuopio and an intermediate-risk population in urban Helsinki. The average daily intake of protein and fat was the same in the two groups but the frequency of consumption of whole-grain cereals and whole-grain bread, as well as the amount of fiber from the bread were higher in Kuopio as compared to Helsinki. Fecal samples collected for 2 days were incubated under anaerobic conditions at 37 degrees C for 96 h, extracted with hexane: peroxide-free diethyl ether, partially purified on a silica Sep-Pak cartridge, and assayed for mutagenic activity using the Salmonella typhimurium/mammalian microsome system. The fecal mutagenic activity was observed with the tester strains TA98 and TA100 with and without microsomal activation in both the population groups. The percentage of samples showing fecal mutagenic ratio greater than 3 with TA98 and TA100 with microsomal activation, was higher in volunteers from Helsinki than in Kuopio.

Nipple aspirates of breast fluid and the epidemiology of breast disease.

Epidemiologic data were obtained, and nipple aspiration attempted, from 289 healthy women, 548 women currently having or with a history of benign breast disease, 153 untreated women with breast cancer, and 106 women previously treated by mastectomy. Breast duct fluid was produced in detectable amounts by 59% of the controls and patients with benign or untreated malignant breast disease; in 35% the volume was in excess of 10 microliters. There were more secretors aged 30 to 50 years (72%), than either those who were younger (52%), or older (44%). Overall, 57% of premenopausal women were secretors, compared with 38% of postmenopausal women. Healthy women who had their menarche before age 13 years were more likely to be secretors. Neither parity, age at first completed pregnancy, nor body weight affected secretor status. There was a trend for the 141 benign breast disease patients aged 40 to 49 years to include more women yielding greater than 10 microliter of fluid (57%) compared with 46 controls (39%). Although breast cancer per se did not appear to influence secretor status, postmastectomy patients were more likely to secrete large fluid volumes, an effect that was particularly pronounced after menopause. Hormonal factors related to age and fibrocystic disease risk and endocrine activity after mastectomy may be the principal determinants influencing the secretion of breast duct fluid.

Brain muscarinic receptors in senile dementia.

Muscarinic receptors were analyzed in various post-mortem brain samples of 39 patients with different types of dementia and of 30 age-matched controls by the specific binding of [3H]QNB. The diagnoses were verified neuropathologically. The binding of [3H]QNB was significantly decreased in the hippocampus, amygdala and nucleus accumbens in patients with Alzheimer's disease (AD) and with combined type of dementia (CD), whereas in patients with multi-infarct dementia (MID) the binding was not significantly decreased in the limbic areas but only in the caudate nucleus. Of the clinical variables, orofacial dyskinesias in patients with AD but not with MID correlated with low brain weight and with the decreased [3H]QNB binding in the striatum and frontal cortex. The results reveal some differences between AD and MID. Changes in muscarinic receptor binding show that the cholinergic neurons in the limbic system are especially vulnerable in patients with AD and CD.

Electrical and chemical stimulation of cervical sympathetic nerves in the dog does not affect secretion of parathyroid hormone.

beta-Adrenergic agonists stimulate PTH release in vitro. The present studies were designed to test the hypothesis that norepinephrine released from sympathetic nerve terminals in the parathyroid glands might be a physiological regulator of PTH secretion. In 22 dogs, electrical stimulation (20 Hz, 1 msec, 50 V nominal) of the right cervical vagosympathetic trunk had no significant effect on release of PTH into the precava, whether the animals were normocalcemic or hypocalcemic, and whether or not they were pretreated with the alpha-adrenergic antagonist phenoxybenzamine. In 4 other dogs, stimulating release of endogenous nerve terminal norepinephrine by iv injection of tyramine (200 micrograms/kg) also failed to raise precaval plasma immunoreactive PTH concentrations. In all studies, induction of mild hypocalcemia raised immunoreactive PTH levels. From these and other studies, we conclude that beta-adrenergic agonists of neural origin are not important regulators of canine PTH release in vivo.

Brain neurotransmitters and neuropeptides in Parkinson's disease.

Parkinson's disease is characterized by a deficiency of dopamine in the nigrostriatal system. However, changes in dopamine neurons were found also outside the extrapyramidal system, showing that there is a more general brain defect than just the loss of substantia nigra dopamine neurons. With regard to the behavior of striatal D-2 receptors it was possible to divide parkinsonian patients into two subgroups, because either a decrease or an increase in the number of D-2 receptors was found. Clinically, the patients with a decreased number of striatal D-2 receptors were more disabled and had lost the beneficial response to levodopa. D-3 receptor binding sites were decreased in the parkinsonian striatum. Changes in the cholinergic-muscarinic receptors in the striatum seem to be related to changes in D-2 receptors, and muscarinic receptor supersensitivity was found in cortical areas. GABA receptor binding was decreased in the substantia nigra. In the parkinsonian brain there seems to be supersensitivity of a population of enkephalin receptors (delta) in the striatum and in the limbic system and also a loss of others (mu) in the striatum. Furthermore, the Met-enkephalin content was decreased in the parkinsonian substantia nigra. A decreased concentration of substance P was found in the substantia nigra of all parkinsonian patients and in the putamen of those patients who had not received levodopa treatment. The somatostatin level was decreased in the frontal cortex in relation to dementia. There are thus multiple neuronal disturbances in the parkinsonian brain, although those of the nigrostriatal dopamine neurons seem to be the greatest and are more closely related to parkinsonian clinical features and to treatment responses.

Metabolic epidemiology of prostatic cancer.

A review of the epidemiological evidence indicates that dietary fat very likely has an etiologic role in the development of prostatic carcinoma. While this effect may be mediated by way of altered hormonal action on the prostate, there is little supporting evidence from assays of plasma or urinary hormones in case-control studies or the investigation of high-risk and low-risk groups. The application of metabolic epidemiology to this problem is most likely to succeed by direct studies of the prostate gland, and the performance of relevant assays on prostatic fluid. Estradiol and estrone levels were found to be higher in prostatic fluid than in serum, whereas for prolactin the reverse was true. Testosterone concentrations were very low in prostatic fluid, perhaps because of the high degree of plasma protein binding. Preliminary data indicated that prostatic fluid estradiol and prolactin levels are elevated in some prostate cancer patients; estrone levels appear to be normal.