Maternal antioxidant concentrations after uncomplicated pregnancies

Background: To analyse the post-partum concentrations of intra- and extra-cellular blood antioxidants in women with uncomplicated pregnancies.

Methods: Whole blood and plasma thiols, plasma vitamin E and C, serum cholesterol and triglyceride, ferric reducing ability of plasma (FRAP) concentrations were compared between women delivered by caesarean section (n=17) or spontaneous delivery (n=10). A repeated mixed model was used for statistical analysis.

Results: The majority of whole blood thiols increased significantly in both groups the first days post-partum. However, within the caesarean group free cysteine, oxidised cysteine, homocysteine and glutathione and plasma cysteine and homocysteine levels dropped significantly after 24 h, while FRAP levels peaked significantly in this group. Plasma vitamin E levels decreased significantly in both groups within 24 to 48 h after delivery. Independent of the way of delivery whole blood and plasma thiols were significantly increased and vitamin E levels were significantly decreased 3 months post-partum while plasma vitamin C levels and FRAP were unchanged compared to ante-partum levels.

Discussion: Decreased plasma vitamin E levels shortly post-partum are associated with decreased lipid peroxidation. The 24 h post-partum drop of some plasma and whole blood thiols in the caesarean group may be due to prolonged fasting.     

Reproductive phase dependent circadian variations of plasma melatonin, testosterone, thyroxine and corticosterone in Indian palm squirrel, Funambulus pennanti

To explain the complex mechanism of environmental influence along with internal hormonal (factors) milieu on daily variations in the circulating levels of melatonin, testosterone, thyroxine and corticosterone were analyzed with the help of inferential statistics (Cosinor rhythmometry) in a seasonally breeding tropical rodent, F. pennanti during the reproductively active (RAP) and inactive phases (RIP). Plasma melatonin, thyroxine and corticosterone levels exhibited a significant circadian oscillation during both the active and inactive phases of the annual reproductive cycle. Melatonin showed higher amplitude during RIP in the circulating plasma. Testosterone presented a peak level during evening hours (16:00 - 18:00 h) during RAP only. The phase of thyroxine was noted ∼09:76 h and ∼10.35 h during active and inactive phases, respectively. Corticosterone showed a peak level at ∼12.00 h during both phases of the reproductive cycle. Further, in this tropical rodent, the minimum difference in photoperiod (∼3 - 4 hours) and maximum variation in temperature (max. 18°C - min. 10°C during RIP and max. 45°C - min. 32°C during RAP) and humidity (85% during RIP and 35% during RAP) regulated the diurnal rhythm of circulating melatonin circadian rhythm by ∼1 hour phase advance during RIP. In conclusion, the studied hormonal rhythms may be part of an integrative system to coordinate reproduction and physiological processes successfully with environmental factors.     

Daily temporal organization of laying in Japanese quail: variability and heritability

In birds, many behavioral and physiological processes that occur during reproduction show daily rhythms in response to environmental temporal constraints. In this study, the individual daily organization of laying and its genetic determinant in Japanese quail (Coturnix coturnix japonica) were analyzed. For this purpose, the oviposition time of 102 randomly chosen females, maintained in long-day photoperiodic conditions (LD 14h:10h) for 1 mon was observed and extreme phenotypes selected. Laying is characterized by two parameters: oviposition interval and laying hour.

The birds showed a specific time of laying during 24 h. All eggs were laid in the afternoon between 6.5 and 14 h after lights on (HALO). Two laying profiles were determined: 20% of females with an oviposition interval greater than 24 h (24.7±0.2 h) (the “delayed” profile) laid progressively later each day until a pause day. The remaining 80% of the females laid at the same time each day, with few pause days and an oviposition interval close to 24 h (24.0±0.2 h) (the “stable” profile). Among the females, showing this last profile, an intra-individual stability and an inter-individual variability of laying hour was established. Two extreme laying phenotypes were then determined: the “early” phenotype (E) for females laying on average between 7.5 and 9.5 HALO and the “late” phenotype (L) for females laying between 12.5 and 14 HALO.

In order to study the genetic basis of the laying hour, three females of each extreme phenotype were selected and crossed with two different males. The E and L females produced 57 F1E and 42 F1L daughters, respectively. F1 females displayed both laying profiles. However, the proportion of females displaying a “delayed” profile was higher in the L line (50%) than in the E line (29.8%). For the “stable” daughters, artificial selection induced an advance in laying hour of 4.7% for the E line and a delay of 4.7% for the L line. Realized heritability was estimated at 0.5. Moreover, the laying hour of the daughters was correlated positively to that of the mothers (N=61;r=0.45). These results support the notion of heritability of oviposition time in Japanese quail.     

Circatrigintan Cycle of Salivary Testosterone in Human Male

Background. Circadian and circannual cycles of testosterone (T) in men are known. The results of our previous study have shown indices for the existence of a male circalunar cycle of T similar to the female one. Objective. The purpose of this study was to investigate possible infradian rhythms of salivary T in young healthy men. Subjects & Methods. Saliva samples from 31 healthy men (18–25 years of age) were collected every second day (for 1 month) and every third day (during the following 1.5 months). T levels were determined by radioimmunoassay. Data were statistically analyzed for infradian rhythmic changes using two different methods: moving averages – zones of extremes, and analysis of rhythmic variance. Results. The data showed rhythmic variations with 2 different infradian periods. The differences between extreme values of the circatrigintan (period of 30 days) and circavigintan (period of 20 days) cycles were found to be highly significant (p < 1E-9; p < 1E-8). Conclusion. We believe that this is the first study demonstrating the existence of circatrigintan and circavigintan rhythms of testosterone in human males. Our findings might have implications in human physiology and pathophysiology.     

Edaravone inhibits acute renal injury and cyst formation in cisplatin-treated rat kidney

Background: Although cis-diamminedichloroplatinum (II) (cisplatin) is an effective anticancer agent, its clinical use is highly limited predominantly due to its adverse effects on renal functions. The present work examined the therapeutic potential of edaravone, a free radical scavenger, for inhibiting cisplatin-induced renal injury.

Methods: Edaravone, 3-methyl-1-phenyl-pyrazolin-5-one, was administrated intravenously at a dose of 30 mg/kg of body weight to male Wistar rats (200-220 g). After 30 min, cisplatin was injected intraperitoneally at a dose of 5 mg/kg of body weight. At the indicated times after the treatment, functions and histological changes of the kidney were analyzed. To test the therapeutic potential of edaravone in chemotherapy, its effect on the anticancer action of cisplatin was examined in ascites cancer-bearing rats.

Results: We found that cisplatin rapidly impaired the respiratory function and DNA of mitochondria in renal proximal tubules, thereby inducing apoptosis of tubular epithelial cells within a few days and chronic renal dysfunction associated with multiple cysts one-year after the administration. Administration of edaravone inhibited the cisplatin-induced acute injury of mitochondria and their DNA and renal epithelial cell apoptosis as well as the occurrence of chronic renal dysfunction and multiple cyst formation. The anticancer effect of cisplatin remained unaffected by intravenous administrating of edaravone.

Conclusions: These results indicate that edaravone may have therapeutic potential for inhibiting the acute and chronic injury of the kidney induced by cisplatin.     

Suppression of circadian rhythms of pineal and testicular hormones following lithium treatment in normal and reversed light-dark cycles, constant light and constant dark in rats

The aim of the current investigation was to study the effect of lithium on circadian rhythms of pineal - testicular hormones by quantitations of pineal and serum serotonin, N-acetylserotonin and melatonin, and serum testosterone at four time points (06.00, 12.00, 18.00 and 24.00) of a 24-hr period under normal photoperiod (L:D), reversed photoperiod (D:L), constant light (L:L) and constant dark phase (D:D) in rats. Circadian rhythms were observed in pineal hormones in all the combinations of photoperiodic regimens, except in constant light, and in testosterone levels in all the photoperiodic combinations. Pineal and serum N-acetylserotonin and melatonin levels were higher than serotonin at night (24.00 hr), in natural L:D cycle, in reversed L:D cycle or similar to normal L:D cycle in constant dark phase, without any change in constant light. In contrast, testosterone level was higher in light phase (12.00 hr through 18.00 hr) than in the dark phase (24.00 hr through 06.00 hr) in normal L:D cycle, in reversed L:D cycle, similar to normal L:D cycle in constant dark (D:D), and reversed to that of the normal L:D cycle in constant light (L:L). Lithium treatment (2 mEq/kg body weight daily for 15 days) suppressed the magnitude of circadian rhythms of pineal and serum serotonin, N-acetylserotonin and melatonin, and testosterone levels by decreasing their levels at four time points of a 24-hr period in natural L:D or reversed D:L cycle and in constant dark (D:D). Pineal indoleamine levels were reduced after lithium treatment even in constant light (L:L). Moreover, lithium abolished the melatonin rhythms in rats exposed to normal (L:D) and reversed L:D (D:L) cycles, and sustained the rhythms in constant dark. But testosterone rhythm was abolished after lithium treatment in normal (L:D)/reversed L:D (D:L) cycle or even in constant light/dark. The findings indicate that the circadian rhythm exists in pineal hormones in alternate light - dark cycle (L:D/D:L) and in constant dark (D:D), but was absent in constant light phase (L:L) in rats. Lithium not only suppresses the circadian rhythms of pineal hormones, but abolishes the pineal melatonin rhythm only in alternate light - dark cycles, but sustains it in constant dark. The testosterone rhythm is abolished after lithium treatment in alternate light - dark cycle and constant light/dark. It is suggested that (a) normal circadian rhythms of pineal hormones are regulated by pulse dark phase in normal rats, (b) lithium abolishes pineal hormonal rhythm only in pulse light but sustains it in constant dark phase, and (c) circadian testosterone rhythm occurs in both pulse light or pulse dark phase in normal rats, and lithium abolishes the rhythm in all the combinations of the photoperiod. The differential responses of circadian rhythms of pineal and testicular hormones to pulse light or pulse dark in normal and lithium recipients are discussed.     

Book Review

LEGGETT, W. F. Ancient and Medieval Dyes. 5 × 8 in. 96 pp. Cloth. Chemical Publishing Co., Brooklyn, N. Y. 1944. $2.25.

Microtechnic In General. McCARTNEY, J. E. A new immersion oil “polyric”. J. Path. & Bact., 56, 265-6. 1944.

NICKERSON, MARK. A dry ice freezing unit for rotary microtomes. Science, 100, 177-8. 1944.

Dyes And Thedx Biological Uses. BERGEIM, FRANK H., and BRAKER, WILLIAM. Homosulfanilamides. J. Amer. Chem. Soc., 66, 1459. 1944.

CALDWELL, W. T., TYSON, F. T., and LAUER, LOTHAR. Substituted 2-sulfonamido-5-aminopyridines. II. J. Amer. Chem. Soc., 66, 1479. 1944.

JOHNS, C. K. Dye concentration in resazurin tablets. Amer. J. Pub. Health, 34, 955-8. 1944.

SMITH, WINSLOW WHITNEY. Relative sensitivity of different phases of growth curve of Bact. salmonicida to alkaline acriflavine. Proc. Soc. Exp. Biol. & Med., 56, 240-2. 1844.

VAN ARENDONK, A. M., and SHOULE, H. A. Dialkylaminoalkyl derivatives of substituted quinolines and quinaldines. J. Amer. Chem. Soc., 66, 1284. 1944.

WHEELER, KEITH, and DEGERING, E. F. Preparation and properties of certain derivatives of sulfamide. J. Amer. Chem. Soc., 66, 1242. 1944.

Animal Microtechnic. BOARDMAN, EDWARD T. Methods for collecting ticks for study and delineation. J. Parasitology, 30, 57-9. 1944.

DICKIE, MARGARET M. A new differential stain for mouse pituitary. Science, 100, 297-8. 1944.

GOVAN, A. D. TELFORD. Fat staining by Sudan dyes suspended in watery media. J. Path. & Bact., 56, 262-4. 1944.

LILLIE, R. D., and ASHBURN, L. L. Supersaturated solutions of fat stains in dilute isopropanol for demonstration of acute fatty degenerations not shown by Herxheimer technic. Arch. Path., 36, 432. 1943.

MULLEN, J. P. A convenient and rapid method for staining glycogen in paraffin sections with Best's carmine stain. Amer. J. Clin. Path., Tech. Sect., 8, 9-10. 1944.

NYKA, W. A method for staining the rickettsiae of typhns in histological sections. J. Path. & Bact., 56, 264. 1944.

POPPER, HANS, GYORGY, PAUL, and GOLDBLATT, H. Fluorescent material (ceroid) in experimental nutritional cirrhosis. Arch. Path., 37, 161. 1944.

SMALL, C. S., and SCHULTZ, M. A. Sustaining faded tissue sections. Amer. J. Clin. Path., Tech. Sect., 7, 66-7. 1943.

YOFFEY, J. M., and PARNELL, J. The lymphocyte content of rabbit bone marrow. J. Anat., 78, 109-12. 1944.

ZIEGLER, E. E. Hematoxylin-eosin tissue stain. An improved, rapid, and uniform technic. Arch. Path., 37, 68. 1044.

Plant Microtechnic. HAASIS, FERDINAND W. Staining rubber in ground or milled plant tissues. Ind. and Eng. Chem., Anal. Ed., 16, 480. 1944.

PARRIS, G. K. A simple nuclear stain and staining technique for Helminthosporia. Phytopathology, 34, 700. 1944.

Microorganisms. DARZINS, E. Rickettsienstudien. Zentbl. Bakl., Abt. I, Orig., 151, 18-20. 1943.

GOHAR, M. A. A staining method for Corynebacterium diphtheriae. J. Bact., 47, 575. 1944.

GRAY, P. H. H. Two-stain method for direct bacteria count. J. Milk Techn., 6, 76. 1943.     

Laboratory Hints from the Literature

DYES AND THEIR BIOLOGICAL USES Burckhalter, J. H., Jones, E. M., Holcomb, W. F., and Sweet, L. A. N-substituted 2-methoxy-6-chloro-9-aminoacridines. J. Amer. Chem. Soc., 65, 2012. 1943.

Galat, Alexander. New processes for sulfanilamide. Ind. and Eng. Chem., Ind. Ed., 36, 192. 1944.

Kumler, W. D., and Daniels, T. C. The relation between chemical structure and bacteriostatic activity of sulfanilamide type compounds. J. Amer. Chem. Soc., 65, 2190. 1943.

Kwartler, C. E., and Lucas, Philip. The preparation of sutfanil-amidoindazoles. J. Amer. Chem. Soc., 65, 1804. 1943.

Mueller, A. C., and Hamilton, C. S. The synthesis of 1-substituted aminobenzo(f)quinolines. J. Amer. Chem. Soc., 65, 1017. 1943.

Popkin, A. H. Derivatives of biphenylsulfonamides. I. Preparation of p-(o-aminopnenyl)-benzenesulfonamide. J. Amer. Chem. Soc., 65, 2043. 1943.

Popkin, A. H., and Perretta, Gertrude M. Derivatives of biphenyl-sulfonamide. II. Derivatives of p-(o-aminophenyl)-benzenesulfonamide. J. Amer. Chem. Soc., 65, 2046. 1943.

Shreve, R. N., and Bennett, R. B. Studies in azo dyes. I. Preparation and bacteriostatic properties of azo derivatives of 2,6-diaminopvridine. J. Amer. Chem. Soc., 65, 2241. 1943.

Shreve, R. N., and Bennett, R. B. Studies in azo dyes. II. Preparation and bacteriostatic properties of azo derivatives of 8-quinolino. J. Amer. Chem. Soc., 65, 2243. 1943.

Siebenmann, C., and Schnitzer, R. J. Chemotherapeutic study of p-nitrobenzoyl- and related compounds. J. Amer. Chem. Soc., 65, 2127 1943.

ANIMAL MICROTECHNIC Barrett, A. M. A method for staining sections of bone marrow. J. Path & Bact., 56, 133-5. 1944.

Barrett, A. M. On the removal of formaldehyde-produced precipitate from sections. J. Path. & Bact., 56, 135-6. 1944.

Chang, Min-Chueh. Disintegration of epidymal spermatozoa by application of ice to the scrotal testis. J. Exp. Biol., 20, 16-22. 1943.

Ercoli, N., and Lewis, M. N. The age factor in response of bone tissue to alizarin dyes and the mechanism of dye fixation. Anat. Rec., 87, 67-76. 1943.

Hess, Manfred, and Hollander, Franklin. Permanent metachromatic staining of gastric mucus smears. J. Lab. and Clin. Med., 29, 321-3. 1944.

Miller, John A. A new method of staining nervous tissue. Ohio J. of Sci., 44, 31-5. 1944.     

Involvement of heme oxygenase as antioxidant defense in soybean nodules

Objective: We have previously demonstrated that the inducible form of heme oxygenase plays a critical role in protecting against oxidative stress in mammals. To gain further insight into the functions of this enzyme in plants, we have tested its activity and expression in soybean nodules subjected to cadmium (Cd) stress.

Materials and methods: Four-weeks-old soybean nodulated plants were treated with different cadmium chloride concentrations (0, 50 and 200 μM) during 48 h. Oxidative stress parameters such as TBARS content, GSH levels and antioxidant enzyme activities were measured as well as heme oxygenase activity and expression. Besides, the effect of biliverdin and Zn-protophorphyrin IX were analized.

Results: Treatment with 200 μM Cd during 48 h caused a 67% increase in TBARS content, whereas GSH decreased 44%, and total superoxide dismutase, gluthatione reductase and guaiacol peroxidase were also inhibited 54, 20 and 60%, respectively. A total of 200 μM Cd produced the overexpression of heme oxygenase-1, as well as a 10-fold enhancement of its activity. Co-administration of biliverdin (10 μM) completely prevented the effects caused by Cd. Treatment with Zn protoporphyrin IX, a strong inhibitor of heme oxygenase, expectedly decreased heme oxygenase-1 activity to half. When the inhibitor was given together with Cd, completely prevented the enzyme induction and oxidative stress parameters were significantly enhanced.

Conclusion: Taking together, these results are indicating that heme oxygenase plays a protective role against oxidative cell damage in soybean nodules.     

Chronobiotic effects of the melatonin agonist LY 156735 following a simulated 9h time shift: results of a placebo-controlled trial

Introduction: The melatonin agonist LY 156735 (LY) is a new investigational drug under development to treat circadian rhythm disorders. The present study assessed the efficacy of LY to alleviate the symptoms of shift lag and to enhance readaptation of desynchronized circadian rhythms to a new time zone.

Subjects and methods: Eight healthy male volunteers of age 25-35 yr participated in three identical trials of 13d duration in a temporal isolation unit separated by washout intervals. A high dose (HD) of 5 mg and a low dose (LD) of 0.5 mg of LY and placebo (PL) were administered double-blinded in a three-period cross-over design. Each trial consisted of an adaptation period, a pre-shift period for baseline measurements, a simulated 9h phase-advance shift, and a post-shift period for follow-up. The time shift was performed at 23:00h of day 6 by advancing the laboratory time to 08:00h of day 7. Double-blind study medication was administered at 14:30h on day 6, and at 22:30h on days 7-10. Subjective ratings of jet lag, alertness, tenseness, and daytime fatigue were assessed using visual analog scales (VAS) and standardized questionnaires. The objective markers of readaptation included core body temperature, wrist actigraphy, cortisol and electrolyte excretion, and a battery of computerized performance tests.

Results: HD but not LD enhanced the readaptation speed of all physiological rhythms investigated, as demonstrated by a significantly faster movement of acrophases towards the post-shift target time. HD (p=0.05) significantly blunted the post-shift deterioration of performance in those tests that were sensitive to shift lag. Parameters of subjective well-being were not significantly affected by either dose.

Conclusion: This pilot study demonstrates the chronobiotic efficacy of LY when taken at a dose of 5 mg/d.     

Book Review

Salmon, M. V. Practical phase-contrast microscopy. The Microscope, 6, 177-88. 1947.

Evans, Titus C. Radioautographs in which the tissue is mounted directly on the photographic plate. Proc. Soc. Exp. Biol, and Med, 64, 813-15. 1947.

Tolbert, B. M., and Branch, G. E. K. The spectra of the doubly charged positive ions of some p,p'-diaminotriphenylmethane dyes. J. Amer. Chem. Soc, 69, 1083-81. 1947.

Van Wyk, J. J., and Clark, W. M. The luminosity and chromaticity of indicators as a function of pH. J. Amer. Chern. Soc, 69, 1296-1301. 1947.

Hamre, Christopher J. Hematopoiesis in the bone marrow of rats recovering from nutritional anemia. J. Lab. & Clin. Med, 32, 756-76. 1947.

Limarzi, Louis R. Evaluation of bone marrow concentration techniques. A modified method for the simultaneous preparation and staining of blood and bone marrow films. J. lab. & Clin. Med, 32, 782-40. 1947.

Heath, O. V. S. Role of starch in light-induced stomatal movement, and a new reagent for staining stomatal starch. Nature, 159, 647-8. 1947.

Cohen, H. A. A new quick method for staining Treponema pallidum. Acta Med. Orientalia, 6, 99-100. 1947.

Henry, H., and Stacey, M. Histochemistry of the Gram-staining reaction for micro-organisms. Proc. Roy. Soc, Ser. B. Biol. Sci, 133, 891-406. 1946.

Para, M. Silver impregnation of spirochetes in tissue sections. Arch. Path, 42, 649. 1946.

Ruiz, Merino, J. A method of staining capsules. Rev. Sanidad e Hig. Publ (Madrid), 20, 1112. 1946.     

Lack of evidence for meteorological effects on infradian dynamics of testosterone

Climatic factors are known to influence the endocrine system. Previous studies have shown that circannual seasonal variations of testosterone might be partly explained by changes in air temperature. Whether infradian variations are affected by meteorological factors is unknown. To analyze possible effects of meteorological parameters on infradian variations of salivary testosterone levels in both sexes, daily salivary testosterone levels were measured during 1 month in 14 men and 17 women. A correlation analysis between hormonal levels and selected meteorological parameters was performed. The results indicate that high testosterone levels are loosely associated with cold, sunny and dry weather in both sexes. However, only the correlations between testosterone and air temperature (men) and actual cloudiness (women) were statistically significant (p < 0,05). Although some correlations reached the level of statistical significance, the effects of selected meteorological parameters on salivary testosterone levels remain unclear. Further longer-term studies concentrating on air temperature, cloudiness and average relative humidity in relation to the sex hormone axis are needed.     

Changes in the Glucocorticoid Function of Adrenals in First Year Schoolboys during Adaptation to the Beginning of School Studies and during the School Year

The glucocorticoid function of adrenals was studied in 23 first-year schoolboys that were subdivided into health groups I and II. The character and time organization of the infradian dynamics of the cortisol were studied during the period of acute adaptation to the beginning of schooling and throughout the school year. The schoolboys of health group II were different from those of group I by both the higher level of the week mesor and its dynamics during the entire school year. By the end of the first half of the year, the structure of cortisol infradian rhythms was changed in the first-year schoolboys of group II: the slow rhythms of cortisol secretion with the period of five to seven days became predominant, and the fact that the absolute values of their amplitudes were significantly increased suggested a tension in the functions of the adrenal cortex.     

Book Reviews

The Biology of Nitric Oxide, vol. 3. Physiological and Clinical Aspects; vol. 4. Enzymology, Biochemistry and Immunology, Portland Press, 1994

Mitochondrial Diseases Editors: L. Ernster, R. Luft and S. Orrenius Publishers: Elsevier

Biothiols in Health and Disease Editors: Lester Packer & Enrique Cadenas Publishers: Marcel Dekker, Inc.     

Twenty-four-hour pattern of angina pectoris, acute myocardial infarction and sudden cardiac death: Role of blood pressure, heart rate and rate-pressure product circadian rhythms

Population-based epidemiology and clinical case studies document a prominent 24-hour pattern in the occurrence of silent and non-silent angina pectoris (AP), acute myocardial infarction (AMI), and sudden cardiac death (SCD). When the data are summarized per 3 - 6 hour intervals of the 24 hours, the temporal pattern of these ischemic heart disease (IHD) events shows a single morning peak between 06:00 and 12:00 h in incidence. However, when the occurrence of such events is examined according to the hour of their occurrence, several studies reveal a second late-afternoon/early-evening minor peak. The true day - night pattern in AP, AMI, and SCD is unknown because the data represent nothing more than the recorded “time of day” of the events. It has been postulated that the day - night pattern in IHD events is at least in part dependent on endogenous circadian rhythms, which are synchronized by the daily routine of sleep in darkness/activity in light. Approximately 20% of the working population is involved in night and rotating shift employment; thus, “time of day” studies are not likely to accurately represent the actual “chronorisk” of vulnerable individuals to IHD events. Moreover, it is likely that the events in the persons comprising the population and clinical case studies were influenced by ongoing treatment with antihypertensive, anticoagulant, and antianginal medications. Details regarding the class, dose, and schedule of such medications are rarely if ever reported in accounts of IHD events. Many of the investigations were conducted decades ago, when short-acting antihypertensive and cardiovascular medications required twice or thrice-a-day dosing, and thus the observed day - night variations could be significantly affected by such multiple treatment timings each day. Thus, the magnitude and nature (single versus multiple peaks) of the reported day - night patterns in AP, AMI, and SCD are suspect, as are their geneses. Presently, it is hypothesized that multiple cyclic exogenous triggers (e.g. posture, physical exertion, emotional stress, and medication scheduling) superimposed upon an endogenous 24-hour susceptibility-resistance pattern that arises from circadian rhythms in heart rate, blood pressure, rate-pressure product, and haemostasis, are major contributory factors.     

Circadian and circannual rhythms of hormonal variables in elderly men and women

A group of fourteen men (73 ± 5 yr of age), and eighteen women (77 ± 7 yr of age) institutionalized at the Berceni Clinical Hospital, Bucharest, Romania, were studied over a 24-hr span once during each season (winter, spring, summer and fall). All subjects followed a diurnal activity pattern with rest at night and ate three meals per day with breakfast at about 0830, lunch at about 1300 and dinner at about 1830. The meals were similar, although not identical for all subjects during all seasons. On each day of sampling blood was collected at 4-hr intervals over a 24-hr span. Seventeen hormonal variables were determined by radioimmunoassay. Statistically significant circadian rhythms were detected and quantitated by population mean cosinor analysis in pooled data from all four seasons in both sexes for ACTH, aldosterone, Cortisol, C-peptide, dehydroepiandrosterone-sulfate (DHEA-S), immunoreactive insulin, prolactin, 17-OH progesterone, testosterone, total T₄ and TSH. In women, estradiol and progesterone also were determined and showed a circadian rhythm during all seasons. Total T, and FSH showed circadian rhythm detection by cosinor analysis in the men only; LH showed no consistent circadian rhythm as group phenomenon in men or women.

A circannual rhythm was detected using the circadian means of each subject at each season as input for the population mean cosinor in the women for ACTH, C-peptide, DHEA-S, FSH, LH, progesterone, 17-OH progesterone and TSH. In the men, a circannual rhythm was detected for ACTH, FSH, insulin, LH, testosterone and T₃. There were phase differences between men and women in ACTH, FSH and LH. In those functions in which both the circadian and circannual rhythms were statistically significant, a comparison of the amplitudes showed in the women a higher circannual rather than circadian amplitude for DHEA-S. In 17-OH progesterone, TSH and C-peptide, the circadian amplitude in women was larger. In men, the circannual amplitude of T₃ was larger than the circadian amplitude and in insulin the circadian amplitude was larger than the circannual amplitude. There was no statistically significant difference between the circadian and circannual amplitudes in the women in ACTH and progesterone and in the men in ACTH and testosterone.     

Plasma Corticosterone, Motor Activity and Metabolic Circadian Patterns in Streptozotocin-Induced Diabetic Rats

Experiments were conducted in male rats to study the effects of streptozotocin-induced diabetes on circadian rhythms of (a) plasma corticosterone concentrations; (b) motor activity; and (c) metabolic patterns. Animals were entrained to LD cycles of 12: 12 hr and fed ad libitum.

A daily rhythm of plasma corticosterone concentrations was found in controls animals with peak levels at 2400 hr and low values during the remaining hours. This rhythm was statistically confirmed by the cosinor method and had an amplitude of 3.37μg/100 ml and the acrophase at 100 hr. A loss of the normal circadian variation was observed in diabetic animals, with a nadir at the onset of light period and high values throughout the remaining hours; cosinor analysis of these data showed no circadian rhythm, delete and a higher mean level than controls.

As expected, normal rats presented most of their motor activity during the dark period with 80+ of total daily activity; the cosinor method demonstrated a circadian rhythm with an amplitude of 60+ of the mean level and the acrophase at 0852 hr. Both diabetic and control rats showed a similar activity during the light phase, but diabetic animals had less activity than controls during the night and their percentage of total daily activity was similar in both phases of the LD cycle (50+ for each one). With the cosinor method we were able to show the persistence of a circadian rhythm in the motor activity of diabetic rats, but with a mesor and amplitude lower than in controls (amplitude rested at 60+ of the mean level) and its acrophase advanced to 0148 hr.

The metabolic activity pattern of diabetic rats also changed: whereas controls showed a greater metabolic activity during the night (70+ food; 82+ water; 54+ urine; 67+ faeces), diabetics did not show differences between both phases of the LD cycle. Water ingested and urine excreted by the diabetic group were higher than normal during light and dark periods; food consumed and faeces excreted were higher than controls only in the light phase.

These data suggest that alterations in circadian rhythms of plasma corticosterone and motor activity are consecutive to the loss of the feeding circadian pattern, due to polyphagia and polydipsia showed by these animals, which need to extend intakes during the light and dark phases.     

Commentary: The Role of Iron-Sulfur Clusters in in vivo Hydroxyl Radical Production

The in vivo production of HO- requires iron ions, H₂O₂ and O₂- or other oxidants but probably does not occur through the Haber-Weiss reaction. Instead oxidants, such as O₂-, increase free iron by releasing Fe(II) from the iron-sulfur clusters of dehydratases and by interfering with the iron-sulfur clusters reassembly. Fe(II) then reduces H₂O₂, and in turn Fe(III) and the oxidized cluster are re-reduced by cellular reductants such as NADPH and glutathione. In this way, SOD cooperates with cellular reductants in keeping the iron-sulfur clusters intact and the rate of HO- production to a minimum.

O₂- and other oxidants can release iron from Fe(II)-containing enzymes as well as copper from thionein. The released Fe(III) and Cu(II) are then reduced to Fe(II) and Cu(I) and can then participate in the Fenton reaction.

In mammalian cells oxidants are able to convert cytosolic aconitase into active IRE-BP, which increases the “free” iron concentration intracellularly both by decreasing the biosynthesis of ferritin and increasing biosynthesis of transferrin receptors.

The biological role of the soxRS regulon of Escherichia coli, which is involved in the adaptation toward oxidative stress, is presumably to counteract the oxidative inactivation of the iron clusters and the subsequent release of iron with consequent increased rate of production of HO.     

Infradian rhythmics of markers of physiologic and metabolic processes in Wistar male rats

This work presents the results of the amplitude-phase structure of the physiological rhythms (locomotor activity) and steroid hormones production (common testosterone and cortisole) in gelded and intact Wistar male rats as well as rats exposed to an information load. The markers have been shown to depend on the social state of the animal. It was proved that there was a phase coincidence of the periods of the biological rhythms of common testosterone (intact rats), cortisole and locomotor activity for animals with different individualand typological features. It was shown that the oscillation period of infradian rhythms of the measured markers of physiologic and metabolic processes in the animals of all groups amounted to 4 days. It was found that infradian rhythms were not sensitive to factors of various genesis.     

Aspartate modulates the circadian patterns of a few biochemical variables in Wistar rats

D-aspartate was used to demonstrate possible sources of excitatory input to the suprachiasmatic nucleus (SCN) in rats. Aspartate (50 mg/kg bodyweight) was orally administrated chronically for 60 days to Wistar rats and 24 h rhythmic patterns of glucose, cholesterol, total protein and aspartate transaminase (AST) were studied under light - dark (LD 12:12 h) cycle. Our results showed acrophase advances in glucose and delays in cholesterol and AST rhythms. Increased mesor and altered amplitude values were found in all rhythms; aspartate levels in the brain were found to be significantly increased in aspartate treated animals. We hypothesised that the altered biochemical rhythms in aspartate treated rats could be due to (1) modulation of neurotransmission in SCN, (2) behavioural rhythms and (3) feeding rhythms.