Decontamination of SARS-CoV-2 contaminated N95 filtering facepiece respirators using artificial sun lamps.

AIMS: Assess the feasibility of using light from artificial sun lamps to decontaminate N95 filtering facepiece respirators (FFRs) contaminated with SARS-CoV-2. METHODS AND RESULTS: FFR coupons or whole FFRs contaminated with 5 log10 TCID50 (target concentration) SARS-CoV-2 in culture media, simulated saliva, or simulated lung fluid were dried for 1-2 h, then exposed to light from tanning and horticulture lamps to assess decontamination. Exposed coupons and whole FFRs showed SARS-CoV-2 inactivation for all matrices tested. Furthermore, FFRs still met performance specifications after five decontamination cycles. CONCLUSIONS: It is feasible that artificial sunlight from these sun lamps can be used to decontaminate FFRs provided the UV dose is sufficient and the light is unobstructed. Furthermore, decontamination can be performed up to five times without degrading FFR performance. SIGNIFICANCE AND IMPACT OF THE STUDY: This research shows a proof of principle that artificial sun lamps may be an option to decontaminate SARS-CoV-2 on N95 FFRs. UV doses required for inactivation to levels below detection ranged from 4 to 37·8 J cm-2 depending on the light source, virus matrix and FFR type.

Decontamination of SARS-CoV-2 contaminated N95 filtering facepiece respirators (FFRs) with moist heat generated by a multicooker.

Decontamination of N95 filtering facepiece respirators (FFRs) is a crisis capacity strategy allowed when there are known shortages of FFRs. The application of moist heat is one decontamination method that has shown promise and is the approach approved in the Steris Steam Emergency Use Authorization (EUA). This effort examines the use of multicookers to apply moist heat, as they are available in retail stores and more affordable than methods requiring more sophisticated equipment. Four of five multicooker models examined met the acceptance criteria for the test and one model was selected for inactivation testing. Tests were performed on four different FFR models with SARS-CoV-2 suspended in culture media, simulated saliva or simulated lung fluid. Moist heat treatment reduced recoverable titres of SARS-CoV-2 virus to levels below the limit of detection in all tests. Furthermore, these four FFR models showed no loss in collection efficiency, inhalation resistance or visual damage after up to 10 decontamination cycles. Two (2) FFR models showed a slight change in strap elasticity (<9%). These data show that moist heat treatment using a multicooker is a viable option for FFR decontamination in a crisis capacity strategy.

Luteinizing hormone: action on the graafian follicle in vitro.

Graafian follicles, dissected intact from the rabbit ovary and incubated for 40 minutes with luteinizing hormone, developed into corpora lutea when autotransplanted under the kidney capsule. Follicles incubated with follicle-stimulating hormone or without hormone degenerated and failed to luteinize. Direct exposure of the mammalian follicle to luteinizing hormone initiates luteinization and formation of the corpus luteum.

Estrogen receptor in the rabbit corpus luteum.

The rabbit corpus luteum contains a cytoplasmic estrogen receptor substance in concentrations comparable to those found in the uterus. Receptor in corpora lutea of nonpregnant rabbits was highest at midluteal phase and decreased before physical regression of corpora was evident. These results support the view that the corpus luteum in this species is an estrogen-responsive tissue.

Fluctuations of the tensor order-parameter modes in a cholesteric liquid crystal.

We use a Landau-de Gennes free energy to calculate the fluctuations of the five independent modes of the tensor order parameter for a cholesteric liquid crystal. Our results include, as a limiting case, the two classical director modes, known as the twist mode and the "umbrella" mode. We find, however, in contrast to the classical director model, that there can be substantial temperature dependence to the umbrella mode, as well as three additional modes near the transition to the isotropic phase. We comment on a recent experiment that suggests that two of these additional modes may have already been detected.

Effects of human chorionic gonadotropin in the rabbit corpus luteum: loss of estrogen receptor and decreased steroidogenic response to estradiol.

The effects of hCG on luteal estrogen receptor and steroidogenesis were examined in 9-day-pseudopregnant rabbits. Twenty-four hours after the injection of ovulatory dosages of hCG (10-100 IU), a dose-related loss of luteal estrogen receptor and in vitro progesterone production was observed. The declining progesterone production was not due to the increased conversion of progesterone to the major metabolite, 20 alpha-dihydroprogesterone. The loss of steroidogenesis induced by hCG was not permanent and could be reversed by estradiol treatment started within 24 h of hCG injection. In those animals with a higher luteal estrogen receptor content at the start of the estrogen treatment, the steroidogenic response was greater. These findings indicate that hCG-induced loss of steroidogenesis is associated with the loss of luteal estrogen receptor. The degree of restoration of progesterone synthesis induced by a 24-h period of estradiol treatment may be related to the content of unoccupied cytoplasmic estrogen receptor in the corpus luteum.

Role of intraluteal estrogen in the regulation of the rat corpus luteum during pregnancy.

The pronounced aromatizing ability of the rat corpus luteum and the ability of estradiol to maintain luteal function. To examine this hypothesis, rats were treated with either estradiol (100 microgram/day), high or low levels of testosterone via Silastic capsules (20 cm or 1 cm in length), or dihydrotestosterone (20-cm capsule) after hypophysectomy and hysterectomy on day 12 of pregnancy. Hypophysectomy and hysterectomy caused serum progesterone and androgen levels, estradiol concentrations in the corpora lutea, and the content of estradiol receptor in luteal cell nuclei to decrease significantly, and caused the cessation of luteal growth. The daily administration of 100 microgram estradiol or of high levels of testosterone via the 20-cm Silastic capsule increased the estradiol concentration in the corpora lutea dramatically, maintained serum progesterone from day 12 through day 15 at concentrations similar to those in pregnant, sham-operated animals, and increased the nuclear content of estradiol receptor in the corpora lutea. Treatment with the small testosterone capsule maintained the serum androgen and progesterone levels, estradiol concentrations in the corpora lutea, and luteal growth at levels observed in pregnant, sham-operated animals. Treatment with the 20-cm dihydrotestosterone capsule did not sustain progesterone secretion and luteal growth. These results suggest that estrogen formed by aromatization within the corpora lutea may play an important role in the regulation of luteal function during pregnancy in the rat.

Properties of nuclear and cytoplasmic estrogen receptor in the rabbit corpus luteum: evidence for translocation.

Nuclear and cytoplasmic estrogen receptors have been identified and characterized in the rabbit corpus luteum, and validated methods are described for the measurement of both unoccupied and total estrogen receptor. Binding was specific for the biologically active estrogens. Equilibrium binding analysis of cytoplasmic estrogen receptor yielded saturable, high affinity binding sites with a Kd of 5.4 x 10(-11) M. Two types of binding sites were found in the nuclear fraction: one with high affinity (Kd = 8.9 x 10(-11) M) and low capacity, the other with low affinity (Kd = 2.7 x 10(-8) M) and high capacity. In the presence of 0.4 M KCl, the sedimentation coefficients of nuclear and cytoplasmic estrogen receptors are 3.4S, while the value is 6.8S for cytoplasmic receptor in buffer without KCl. Twenty minutes after an iv injection of 2 micrograms 17 beta-estradiol, the available and total cytoplasmic estrogen receptors were depleted. This depletion was accompanied by concomitant and stoichiometric accumulation of receptor in the nucleus, indicating an apparent translocation of the receptor. In corpora lutea of normal rabbits, approximately 80% of the total nuclear receptor is unoccupied. Evidence is presented to suggest that nuclear receptor sites might be ordinarily occupied with estradiol, but during isolation of the nuclear fraction these sites become available or unoccupied. The identification of nuclear estrogen receptor and the phenomenon of translocation of cytoplasmic receptor to the nucleus suggest a similarity of estrogen action in the rabbit corpus luteum and other estrogen target tissues.

Progesterone synthesis in developing rabbit corpora lutea in the absence of follicular estrogens.

We have investigated the role of 17beta-estradiol in the early development of the rabbit corpus luteum. Ectopic corpora lutea were established in all animals by autotransplanting preovulatory follicles beneath the kidney capsule 6.5 to 8 h after mating (day 0). At this time, the rabbits were bilaterally ovariectomized and in some of these rabbits a Silastic capsule containing crystalline 17beta-estradiol was implanted SC. Mean serum concentration of estradiol in rabbits with an estradiol impant was 16.4 pg/ml. In rabbits without an estradiol implant, the estradiol concentration averaged 1 pg/ml despite the presence of transplanted luteinized follicles. Daily blood samples were analyzed for progesterone by radioimmunoassay. Ectopic corpora lutea developed in rabbits with or without estradiol treatment. Serum progesterone concentrations in the two groups increased above castrate values and were not significantly different from one another through day 5. After day 5, progesterone concentrations steadily increased in rabbits treated with estradiol and reached a value of 4.8 ng/ml by day 10. In contrast serum progesterone steadily decreased after day 5 in rabbits without estradiol treatment to a level of 450 pg/ml by day 10. Hysterectomy on day 0 did not prevent this decline in progesterone, indicating that a uterine luteolytic agent was not involved. Total luteal weight on day 10 was positively correlated with serum progesterone concentration (r equals .92; P greater than 0.01). These results indicate that for a period of approximately 5 days afte r ovulation, the development of the rabbit ectopic corpus luteum and the secretion of progesterone are autonomous from estradiol secreted by ovarian follicles. After this time, there is an absolute requirement for estrogen which permits further development of the corpus luteum and the continuation of progesterone synthesis.

Synthesis of 17beta-estradiol by isolated ovarian tissues of the pregnant rat: aromatization in the corpus luteum.

Corpora lutea from pregnant rats were incubated to determine their ability to produce 17beta-estradiol and to aromatize testosterone in vitro. Corpora lutea and non-luteal ovarian tissues were removed from rats on days 7, 15, and 22 of pregnancy, and these tissues were immediately frozen or incubated separately in medium 199 at 37 C in an atmosphere of 95% O2-5% CO2 for 4 h. 17Beta-Estradiol in tissue and medium were quantified by a highly specific radioimmunoassay. The estradiol content ivnariably increased in non-luteal tissues during incubation, while it decreased or remained the same in incubated corpora lutea. The synthesis in non-luteal tissues, which was 18 to 400-fold greter. The incubation of corpora lutea (5 to 25 mg of tissue) with testosterone (200 ng) on days 7, 15, and 22 of pregnancy resulted in a mean accumulation of 17beta-estradiol in medium of 2.5 x 103 pg/mg tissue, compared with a mean value of 6 pg/mg for luteal tissue removed from the same ovaries and incubated without testosterone. The incubation of corpora lutea from 15-day pregnant rats with (7alpha-3H)-testosterone resulted in 15% conversion to presumptive (7alpha-3H)17beta-estradiol, which was isolated identically to estradiol isolated for radioimmunoassay. Recrystallization to constant specific activity revealed a high degree of radiochemical purity (75%) of the isolated (3H)estradiol. Rat diaphragm muscle and rabbit corpora lutea did not aromatize testosterone to 17beta-estradiol in amounts detectable by radioirpora lutea in vitro is virtually diol by non-luteal ovarian tissues. However,the corpora lutea show a striking capacity to aromatize testosterone, which might explain the high estradiol content of the rat corpora lutea during pregnancy. The physiological significance of this aromatizing system and of 17beta-estradiol in the corpus luteum is unknown but may be related to the luteotropic action of estradiol in the pregnant rat.

Insulin-like growth factor-I stimulates steroidogenesis in rabbit luteal cells.

A potential role of insulin-like growth factor I (IGF-I) in the regulation of steroidogenesis in the rabbit corpus luteum was investigated using a primary culture of luteal cells obtained 3 days after ovulation. Dissociated cells were cultured for 1 day in the presence of medium 199 and 10% fetal bovine serum; thereafter, the cells were cultured in medium 199 containing 0.1% BSA, gentamicin (50 micrograms/ml), and hormones or growth factors, and without serum. IGF-I (human recombinant, 100 ng/ml) was as effective as LH (ovine, 10 ng/ml) in maintaining progesterone accumulation through 4 days of culture. Estradiol (10(-8) M), either alone or in combination with LH or IGF-I failed to stimulate progesterone accumulation, which was not surprising since these cells did not possess estrogen receptors. The stimulation of progesterone by IGF-I was not detectable until 24-36 h after introduction of the growth factor to the cultures, whereas stimulation by LH was observed within 2 h. The steroidogenic effect of IGF-I was not attributable to increased cell number, as DNA values or [3H]thymidine incorporation were unchanged by IGF-I. IGF-I increased functional enzymatic activity, observed as increased progesterone accumulation in the presence of 25-hydroxycholesterol used as exogenous substrate. These data indicate that luteal cells have the capacity to respond to IGF-I, raising the possibility that IGF-I has a role in the regulation of steroidogenesis in the rabbit corpus luteum.

Tumor necrosis factor-a (TNF-a) production and localization of macrophages and T lymphocytes in the rabbit corpus luteum.

Utilizing immunocytochemistry numerous macrophages were localized in regressing corpora lutea. In contrast, few macrophages were observed in young corpora lutea. Regressing corpora lutea readily produced TNF-a in vitro in response to lipopolysaccharide, whereas young corpora lutea produced significantly less TNF-a. T lymphocytes were identified in young corpora lutea preceding the appearance of macrophages. These observations suggest that cells of the immune system and cytokines could be important participants in physiological regression of the corpus luteum.

Control of corpus luteum function in the pregnant rabbit: role of estrogen and lack of a direct luteotropic role of the placenta.

The corpus luteum is essential for pregnancy maintenance in the rabbit and appears to require two luteotropins: estrogen from ovarian follicles and a placental luteotropic factor. We have investigated the role of the placental luteotropic factor in maintaining corpus luteum function in the pregnant rabbit in the absence of estrogen. In Exp 1, follicular estrogen was withdrawn on day 21 of pregnancy by ovulating follicles with 10 IU hCG. In Exp 2, estrogen was withdrawn in hypophysectomized pregnant rabbits on day 21 by removing an estradiol (E2) implant. In the presence of this estrogen implant, luteal function and pregnancy are maintained after hypophysectomy, performed on day 4 of pregnancy. In both experiments, fetoplacental viability was ensured by treating the rabbits with medroxyprogesterone acetate (MPA). In both Exp 1 and 2, withdrawal of estrogen on day 21 of pregnancy caused a dramatic decline in serum progesterone concentrations by day 22. Serum progesterone concentrations remained low, and corpora lutea regressed, although viable fetuses were maintained with MPA. In animals not receiving MPA, estrogen withdrawal caused the loss of luteal function, followed by abortion on days 23-24. In contrast, estrogen replacement (via E2 implant) on day 22 in Exp 1 was fully capable of restoring serum progesterone concentrations to pretreatment values on days 24-27 in MPA-treated rabbits. In rabbits not receiving MPA, estrogen replacement also restored serum progesterone concentrations and prevented abortion. These results provide further evidence that estrogen is essential for normal luteal function in the pregnant rabbit. In the absence of estrogen, the rabbit placenta maintained by the progestagen MPA has no direct luteotropic activity.

Etiology of anovulation in the immature alloxan-diabetic rat treated with pregnant mare's serum gonadotropin: absence of the preovulatory luteinizing hormone surge.

The effects of alloxan-induced diabetes on ovulation and other ovarian responses were investigated in immature rats injected with PMS gonadotropin (PMSG, 15 IU/100 g) on day 30 of age. Rats were killed on day 32 (presumed proestrus) or on day 33, at which time the oviducts were examined for ova. Ovarian weight gain was similar in control and diabetic rats and Graafian follicles were present in both groups on day 32. None of the diabetic rats ovulated while 96% of the control rats ovulated. Anovulation in diabetic rats could not be attributed to a drug side-effect of alloxan or to a lack of ovarian responsiveness, as 90% of the animals ovulated after treatment with insulin or with hCG (5 IU). Measurements of serum estradiol and LH on the morning of presumed proestrus revealed that concentrations of these hormones were not different in control and diabetic rats. However, measurements of LH in blood samples taken in the afternoon from control rats showed an LH surge, whereas no LH surge was found in diabetic rats. Thus, anovulation in immature diabetic rats treated with PMSG is not caused by an attenuation of ovarian responsiveness or by decreased secretion of estradiol, but rather is due to the loss of the LH surge.

Premature regression of corpora lutea in pseudopregnant rabbits following the removal of polydimethylsiloxane capsules containing 17 beta-estradiol.

17-beta-Estradiol, which is luteotropic in rabbits, was administered during pseudopregnancy via polydimethylsiloxane (Silastic) implants to determine the effects on serum progesterone concentrations. Implants which released estradiol at a rate of approximately 2 mug/day were place beneath the skin the day after sterile mating and ovulation (day 0). Blood (3 ml) was obtained from the marginal ear vein on days 3, 6, 9, 10, 11 and 12. Serum estradiol levels, determined by radioimmunoassay, were 2- to 3-fold higher in estradiol-treated rabbits (11.7 plus or minus 1.2 pg/ml) than in untreated pseudopregnant controls (5.9 plus or minus 1.4 pg/ml). Weights of corpora lutea in treated and control rabbits were not different at the conclusion of the experiment on day 12. Serum progesterone concentrations, also determined by radioimmunoassay, were not significantly different between treated and control animals. However, when estradiol implants were removed from other rabbits on day 10, a rapid decline in serum progesterone occurred, from 14.0 plus or minus 2.4 to 2.6 plus or minus 0.8 ng/ml 24 h later. By comparison, serum progesterone concentrations in rabbits with estradiol implants left in place and in untreated rabbits on day 12 were similar (similar to 12 ng/ml). The premature decline in serum progesterone was accompanied by a decrease in the wet weight of corpora lutea. Other experiments revealed: 1) a precipitous fall in serum estradiol to basal values within 2 h after estradiol implants were removed, preceding the decline in serum progesterone by approximately 6 to 10 h; 2) reduced levels of estradiol in ovarian venous blood, but elevated levels of estradiol in peripheral arterial blood of rabbits with estradiol impants. The inability to elevated estradiol to increase serum progesterone or weights of corpora litea suggests that the luteotropic effect is maximal when estradiol is present at physiological concentrations. Following the continuous administration of estradiol, ovarian secretion of estradiol appears diminished and the corpora lutea become dependent upon the exogenous estradiol for luteotropic support. Although the ovaries continue to release measureable quantities of estradiol, this is inmeasurable quantities of estradiol, this is insufficient to prevent regression of corpora lutea when exogenous estradiol is rapidly withdrawn from the circulation.

Lack of gonadotropic activity in the rabbit blastocyst prior to implantation.

Recent reports of an LH-like hormone in the rabbit preimplantation blastocyst and of elevated serum progesterone levels in the presence of unimplanted blastocysts prompted us to characterized further the biological activity of the presumed gonadotropin. Progesterone was measured by a highly specific radioimmunoassay in sera obtained from pregnant and pseudopregnant rabbits after mating (day 0) to fertile or vasectomized males. On days 3, 4, 5, and 6, which represent the preimplantation period, mean progesterone concentrations (ng/ml +/- SE) were 4.3 +/- 0.7, 5.1 +/- 0.5, 6.8 +/- 1.1, and 9.0 +/- 1.9 in 5 pseudopregnant rabbits and 4.1 +/- 0.4, 6.7 +/- 0.6, 5.9 +/- 0.9, and 7.0 +/- 0.8 in 7 pregnant rabbits. In a separate experiment, serum progesterone concentrations in 6 pseudopregnant and 8 pregnant rabbits were 10.1 +/- 0.7 ng/ml and 13.7 +/- 1.1 (P less than 0.02), respectively on days 11-12. Thus, serum progesterone concentrations were not different in pregnant and pseudopregnant rabbits before the time of implantation (day 7), but were higher in pregnant rabbits after implantation. Blastocysts obtained on day 6 and incubated with a cell suspension of immature rat ovaries failed to stimulate the accumulation of progesterone in medium, in contrast to hCG, which was active even in the presence of blastocysts. Day-6 blastocysts also failed to stimulate the accumulation of testosterone from decapsulated rat testes and of progesterone from rabbit ovarian tissues in vitro. A gonadotropic effect of the conceptus can be observed in the rabbit within 4 to 5 days after implantation. However, we find no evidence for the existence of an LH-like hormone in the preimplantation blastocyst which stimulates the rabbit ovary to secrete progesterone.

Regulation of blood flow to the rabbit corpus luteum: effects of estradiol and human chorionic gonadotropin.

We tested the hypothesis that estrogen and hCG can modify blood flow in the rabbit corpus luteum. Radioactively labeled microspheres were used to measure luteal blood flow in pseudopregnant rabbits in which estrogen had been withdrawn to initiate premature luteal regression and in pseudopregnant rabbits injected with hCG. Removal of estradiol-filled Silastic capsules on day 10 of pseudopregnancy caused an 80% decrease in the serum progesterone concentration within 24 h. Despite the decline in progesterone secretion, luteal blood flow remained at very high levels and was not different from that in control rabbits treated continuously with estradiol. Replacement of estradiol-filled capsules for 3 h did not change the high rate of blood flow to the corpus luteum, but blood flow in the uterus, vagina, and ovarian stroma was increased. The injection of hCG (10 IU, iv) on day 10 of pseudopregnancy caused a 3-fold increase in blood flow to the nonluteal portion of the ovary and a 3-fold increase in the serum progesterone concentration, but luteal blood flow did not change. We conclude that the acute actions of estradiol or hCG in the rabbit corpus luteum are not mediated by changes in luteal blood flow. Further, the results suggest that the luteal vasculature is regulated differently from the vasculature of other estrogen-responsive tissues and that blood flow in the nonluteal tissues of the ovary can be regulated independently of blood flow in the corpus luteum.

The biosynthesis of cholesterol side-chain cleavage cytochrome P-450 in the rabbit corpus luteum depends upon estrogen.

To gain a better understanding of the luteotropic action of estrogen, we have investigated the effect of estrogen on the synthesis of the enzyme, cholesterol side-chain cleavage cytochrome P-450 (P-450scc) in the rabbit corpus luteum. Using an established protocol, rabbits were treated with estradiol, and the estradiol was then withdrawn on day 9 of pseudopregnancy, which caused an 88% fall in serum progesterone within 48 h. In other rabbits, estradiol was replaced at 48 h which stimulated a 6.6-fold increase in serum progesterone concentration within the next 24 h. Luteal tissues were incubated with [35S]methionine and homogenized, and a mitochondrial fraction lysate was obtained. Equal trichloroacetic acid-precipitable radioactivity was taken for immunoprecipitation using a well-characterized polyclonal antiserum against bovine adrenal P-450scc. The immunoisolated proteins were resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and radioactivity was visualized by autofluorography. The results indicate that the rate of synthesis of P-450scc in 48 h-estradiol withdrawn animals was markedly reduced, and by 72 h of withdrawal was barely detectable. When estradiol was reintroduced, the synthesis of P-450scc was increased. Despite the prominent changes in P-450scc synthesis, immunoblotting revealed only a minimal (approximately 30%) decrease in relative P-450scc content by 72 h after estradiol withdrawal. Analyses of DNA and protein contents of luteal tissues revealed an increase in DNA per mg luteal tissue, a decline in total tissue protein/DNA ratio, but no change in mitochondrial fraction protein/DNA ratio after estrogen withdrawal. The results indicate that de novo synthesis of P-450scc in the corpus luteum is sensitive to estrogen; however, the estrogen-sensitive rate-limiting step(s) for steroidogenesis are at other sites in the steroid biosynthetic pathway.

The autonomy of the rabbit corpus luteum.

The rabbit corpus luteum possesses LH receptors that are coupled to adenylyl cyclase, but paradoxically it does not require LH as a luteotrophic factor for the maintenance of progesterone secretion. This suggests that rabbit luteal cells may not respond physiologically to LH. Therefore, the present study was undertaken to investigate the responsiveness of the rabbit corpus luteum of pseudopregnancy to human chorionic gonadotrophin (hCG) which acts on the same receptor as LH. Pseudopregnancy was induced by injection of 40 IU pregnant mare serum gonadotrophin followed 50 h later by an injection of 40 IU hCG (day 0). On days 7 and 11 of pseudopregnancy, corpora lutea were obtained and incubated for 2 or 5 h in the presence of either 0.1 or 1 microgram/ml hCG or 1 mM monobutyryl cyclic AMP (bcAMP). Neither hCG nor bcAMP stimulated progesterone production by the isolated corpus luteum, despite a sustained high rate of progesterone production by the tissue throughout the incubation period. By contrast, Graafian follicles removed from the same ovaries and incubated under the same conditions responded both to hCG and bcAMP with large increases in progesterone production. To determine whether the cyclic AMP content of the corpus luteum was altered by in vitro exposure to hCG, day 7 and day 11 corpora lutea were incubated for 5 or 15 min with various concentrations of hCG, and cyclic AMP in the tissue was then measured. Even at the highest concentration of hCG tested (10 micrograms/ml), the cyclic AMP content of the corpus luteum was unaltered.(ABSTRACT TRUNCATED AT 250 WORDS)

Human non-24-hour sleep-wake cycles in an everyday environment.

A sighted college student maintained a sleep-wake cycle longer than 24 hr in his everyday environment for more than half of nearly four years. The range of sleep-wake periods and the amount and regularity of sleep are consistent with those found in time-free environments. Episodes of 24 hr periodicity suggest that social cues or obligations are effective entraining agents. He reported more sleep difficulties while on a 24 hr than a non-24-hr schedule.