The relative potency of the Crick-Harper-Raper unit and the GIH clinical unit of secretin. (57/1163)

A reinvestigation of the relationship between the Crick-Harper-Raper (CHR) and the GIH clinical units (CU) of secretin has been undertaken in anaesthetized cats with the knowledge that for some time before 1970 the CHR standard used by The Boots Company to assay secretin had lost some specific activity. One clinical unit of GIH secretin (batch no. 17421) is 3-8 times more potent than 1 Crick-Harper-Raper unit of restandardized Boots secretin (batch no. 142) in increasing the flow rate of pancreatic juice, and four times more potent in increasing the amount of bicarbonate.  (+info)

Tuning pacemaker frequency of individual dopaminergic neurons by Kv4.3L and KChip3.1 transcription. (58/1163)

The activity of dopaminergic (DA) substantia nigra (SN) neurons is essential for voluntary movement control. An intrinsic pacemaker in DA SN neurons generates their tonic spontaneous activity, which triggers dopamine release. We show here, by combining multiplex and quantitative real-time single-cell RT- PCR with slice patch-clamp electrophysiology, that an A-type potassium channel mediated by Kv4.3 and KChip3 subunits has a key role in pacemaker control. The number of active A-type potassium channels is not only tightly associated with the pacemaker frequency of individual DA SN neurons, but is also highly correlated with their number of Kv4.3L (long splice variant) and KChip3.1 (long splice variant) mRNA molecules. Consequently, the variation of Kv4alpha and Kv4beta subunit transcript numbers is sufficient to explain the full spectrum of spontaneous pacemaker frequencies in identified DA SN neurons. This linear coupling between Kv4alpha as well as Kv4beta mRNA abundance, A-type channel density and pacemaker frequency suggests a surprisingly simple molecular mechanism for how DA SN neurons tune their variable firing rates by transcriptional control of ion channel genes.  (+info)

Night shift work, light at night, and risk of breast cancer. (59/1163)

BACKGROUND: Exposure to light at night may increase the risk of breast cancer by suppressing the normal nocturnal production of melatonin by the pineal gland, which, in turn, could increase the release of estrogen by the ovaries. This study investigated whether such exposure is associated with an increased risk of breast cancer in women. METHODS: Case patients (n = 813), aged 20-74 years, were diagnosed from November 1992 through March 1995; control subjects (n = 793) were identified by random-digit dialing and were frequency matched according to 5-year age groups. An in-person interview was used to gather information on sleep habits and bedroom lighting environment in the 10 years before diagnosis and lifetime occupational history. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by use of conditional logistic regression, with adjustment for other potential risk factors. RESULTS: Breast cancer risk was increased among subjects who frequently did not sleep during the period of the night when melatonin levels are typically at their highest (OR = 1.14 for each night per week; 95% CI = 1.01 to 1.28). Risk did not increase with interrupted sleep accompanied by turning on a light. There was an indication of increased risk among subjects with the brightest bedrooms. Graveyard shiftwork was associated with increased breast cancer risk (OR = 1.6; 95% CI = 1.0 to 2.5), with a trend of increased risk with increasing years and with more hours per week of graveyard shiftwork (P =.02, Wald chi-squared test). CONCLUSION: The results of this study provide evidence that indicators of exposure to light at night may be associated with the risk of developing breast cancer.  (+info)

Rotating night shifts and risk of breast cancer in women participating in the nurses' health study. (60/1163)

BACKGROUND: Melatonin shows potential oncostatic action, and light exposure during night suppresses melatonin production. There is little information, however, about the direct effect of night work on the risk of cancer. We investigated the effect of night work in breast cancer. METHODS: We examined the relationship between breast cancer and working on rotating night shifts during 10 years of follow-up in 78 562 women from the Nurses' Health Study. Information was ascertained in 1988 about the total number of years during which the nurses had worked rotating night shifts with at least three nights per month. From June 1988 through May 1998, we documented 2441 incident breast cancer cases. Logistic regression models were used to calculate relative risks (RRs) and 95% confidence intervals (CIs), adjusted for confounding variables and breast cancer risk factors. All statistical tests were two-sided. RESULTS: We observed a moderate increase in breast cancer risk among the women who worked 1-14 years or 15-29 years on rotating night shifts (multivariate adjusted RR = 1.08 [95% CI = 0.99 to 1.18] and RR = 1.08 [95% CI = 0.90 to 1.30], respectively). The risk was further increased among women who worked 30 or more years on the night shift (RR = 1.36; 95% CI = 1.04 to 1.78). The test for trend was statistically significant (P =.02). CONCLUSIONS: Women who work on rotating night shifts with at least three nights per month, in addition to days and evenings in that month, appear to have a moderately increased risk of breast cancer after extended periods of working rotating night shifts.  (+info)

Physical and chemical aspects of saliva as indicators of risk for dental caries in humans. (61/1163)

The etiology and pathogenesis of dental caries are known to be multifactorial, but the interplay between intrinsic and extrinsic factors is still not fully understood. As in other host/parasite interactions, there appear to be marked variations in individual susceptibility to the disease. It therefore is likely that intrinsic host factors play a key role in modulating the initiation and progression of caries. The objective of this systematic review was to evaluate critically the evidence supporting the role and effects of saliva in caries pathogenesis. The full-length evidence report, including evidence tables, and the structured abstract presented at the NIH/NIDCR Consensus Development Conference on the Diagnosis and Management of Dental Caries Throughout Life, March 26-28. 2001, can be accessed at the web site http://www.nidcr.nih.gov. The present abridged report is a summary of the main findings from our evidence-based review.  (+info)

An abnormality of oestrogen feedback in amenorrhoea-galactorrhoea. (62/1163)

Fourteen patients with amenorrhoea and hyperprolactin-anemia but no evidence of pituitary tumours were each given an intramuscular injection of 1 mg oestradiol benzoate. Thirteen patients failed to release luteinizing hormone in response to the oestrogen. This hypothalamic abnormality may help to explain the menstrual disturbances in subjects with hyperprolactinaemia.  (+info)

Possible mechanism of the inhibitory effect of ouabain on renin secretion from rat renal cortical slices. (63/1163)

1. The effects of ouabain on renin secretion by rat renal cortical slices were studied. 2. Renin secretion was inhibited by 10(-3) M-ouabain in the presence of free Ca (10(-4) to 2.6 x 10(-3) M). Inhibition was blocked at Ca less than 10(-8) M. 3. The effect of free Ca on ouabain-inhibition was shown to be independent of the presence of EGTA, completely reversible, and unrelated to passive leakage of renin from non-viable cells, as assessed by simultaneous release of lactate dehydrogenase activity (LDH). 4. It is proposed that, as a result of inhibition of Na, K-ATPase by ouabain, (a) intracellular Na increases in the renin-secreting juxtaglomerular cells, (b) intracellular Ca increases, via an Na-Ca exchange mechanism, and (c) that Ca accumulation, in some unknown manner, inhibits renin secretion.  (+info)

Circadian secretion of cortisol in bipolar disorder. (64/1163)

OBJECTIVE: To compare the 24-h cortisol secretion profiles of normal control subjects and patients with bipolar disorder who were in the depressive, manic and euthymic phases of the disorder. PARTICIPANTS: Eighteen patients, 25-62 years of age, in depressed (n = 5), manic (n = 5) or euthymic (n = 8) phase of bipolar disorder recruited through a psychiatric outpatient clinic, and 5 control subjects, 24-41 years of age, recruited through advertisement or word of mouth. OUTCOME MEASURES: Subjects were interviewed and symptom ratings were obtained using the Hamilton Depression Rating Scale, Beck Depression Inventory and Young Mania Scale. Blood collection began at 0800 and continued at hourly intervals for 24 h. Serum cortisol levels were assayed using a validated commercial radioimmunoassay kit. RESULTS: An analysis of variance of the area under the cortisol 24-h time-concentration curve (AUC) revealed a significant difference between the control group and patient groups (F = 3.69, p = 0.03). the mean AUCs of the patients in the depressed (263.4 micrograms/dL) and hypomanic (262.2 micrograms/dL) phases were beyond the 95% confidence interval for the controls (120.9-253.3 micrograms/dL). There were no significant group differences in cosinor acrophase and no significant effects of sex, education, age of illness onset, duration of illness or duration of mood state at time of testing on the cortisol measures. Pearson correlations between symptom rating scores and cortisol secretion variables were not significant. CONCLUSION: The increases in cortisol secretion in patients in both the depressed and manic phases of bipolar disorder suggest that cortisol level is probably not a state marker in bipolar disorder.  (+info)