Six-year healthcare trajectories of adults with anxiety and depressive disorders: Determinants of transition to specialised mental healthcare.

BACKGROUND: To investigate potential facilitators and barriers for patients receiving specialised mental healthcare using a longitudinal design. METHODS: Longitudinal data on 701 adult participants with a depressive and/or anxiety disorder were derived from the Netherlands Study of Depression and Anxiety (NESDA). Demographic, clinical and treatment determinants at baseline were assessed with self-report questionnaires and the Composite International Diagnostic Interview (CIDI 2.1). Transition to specialised mental healthcare was assessed at one, two, four, and six-year follow-up with a self-report resource use questionnaire (TiC-P). RESULTS: 28.3% of patients with a depressive and/or anxiety disorder transitioned from receiving no care or primary mental healthcare to specialised mental health services during six-year follow-up. The multivariate Cox regression model identified suicidal ideation, younger age, higher education level, openness to experience, pharmacological treatment, prior treatment in primary mental healthcare and perceived unmet need for help as determinants of transition, explaining 8-18% of variance. LIMITATIONS: This study focused on baseline determinants of future transition to specialised mental healthcare. Recovery and remittance of depression and anxiety in relation to transition were not studied. CONCLUSIONS: Not all key clinical guideline characteristics such as severity of symptoms and comorbidity were predictive of a transition to specialised mental healthcare, while non-clinical factors, such as age and perceived unmet need for help, did influence the process.

Intravenous immunoglobulin is an effective treatment for refractory cutaneous dermatomyositis.

BACKGROUND: Cutaneous dermatomyositis (DM) is often refractory to multiple systemic medications, suggesting a need for effective alternative treatments. AIM: To investigate the effects of intravenous immunoglobulin (IVIG) on patients with refractory cutaneous DM. METHODS: This was a retrospective review of 42 patients treated with IVIG for refractory cutaneous DM at our institution with clinical data available at DM diagnosis. IVIG was initiated for refractory cutaneous DM alone (n = 15) or refractory cutaneous and muscle/lung disease (n = 27) in patients with various DM subtypes. RESULTS: Overall, 83% of patients had cutaneous DM improvement, including 87% treated for refractory skin disease alone and 81% treated for refractory skin/muscle/lung disease. Cutaneous DM improvement occurred regardless of DM subtype, and was observed after a mean of 1.82 ± 1.38 IVIG cycles. No statistically significant clinical predictors of IVIG response or lack of response were detected. IVIG use resulted in decreased systemic glucocorticoid exposure with or without a decrease in steroid-sparing immunosuppressive medications in 80% of patients. This study is limited by its retrospective nature and lack of objective cutaneous DM activity assessment. CONCLUSION: Use of IVIG resulted in improvement of refractory cutaneous DM in the vast majority of patients relatively soon after initiation and regardless of DM subtype or clinical manifestations. Additionally, IVIG allowed decrease or discontinuation of immunosuppressive medications in 80% of patients. These findings suggest that IVIG can be a clinically efficacious and cost-effective treatment for refractory cutaneous DM and warrants prospective study.

Identification of soil heavy metal sources and improvement in spatial mapping based on soil spectral information: A case study in northwest China.

In a sewage irrigation area of northwest China, 52 topsoil samples were collected to measure the contents of arsenic (As), chromium (Cr), copper (Cu), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn). To identify their sources, multivariate statistics and geostatistics were applied to separate pedogenic elements (As and Mn) from anthropogenic elements (Cr, Cu, Hg, Ni, Pb and Zn). The accumulation of soil Hg was mainly attributed to long-term sewage irrigation, whereas Cr, Ni and Zn were mainly from industrial activities and dust deposition. In addition to the impacts of industry and dust, traffic-related factors were the main sources of Pb and Cu contamination. Based on the relationships of heavy metals with various soil properties and reflectance spectra, co-kriging (CK) was used to improve the interpolation of heavy metals. Comparatively, soil spectra were more suitable as covariates due to their ease and low-cost of collecting as features.

Rapid identification of soil cadmium pollution risk at regional scale based on visible and near-infrared spectroscopy.

Soil heavy metal pollution due to long-term sewage irrigation is a serious environmental problem in many irrigation areas in northern China. Quickly identifying its pollution status is an important basis for remediation. Visible-near-infrared reflectance spectroscopy (VNIRS) provides a useful tool. In a case study, 76 soil samples were collected and their reflectance spectra were used to estimate cadmium (Cd) concentration by partial least squares regression (PLSR) and back propagation neural network (BPNN). To reduce noise, six pre-treatments were compared, in which orthogonal signal correction (OSC) was first used in soil Cd estimation. Spectral analysis and geostatistics were combined to identify Cd pollution hotspots. Results showed that Cd was accumulated in topsoil at the study area. OSC can effectively remove irrelevant information to improve prediction accuracy. More accurate estimation was achieved by applying a BPNN. Soil Cd pollution hotspots could be identified by interpolating the predicted values obtained from spectral estimates.

Neonatal thyroid screening results are related to gestational maternal thyroid function.

OBJECTIVE: To study the relationship between maternal thyroid function at each pregnancy trimester and neonatal screening results. BACKGROUND: Overt maternal thyroid dysfunction during gestation is associated with poor neonatal thyroid function. However, research on the relationship between suboptimal maternal thyroid function (assessed at three trimesters) and neonatal thyroid screening outcome is scarce. DESIGN/PATIENTS: Prospective follow-up study during three trimesters of gestation in 886 Dutch Caucasian healthy pregnant women followed from 12-week gestation until term delivery (>37 weeks) and their neonates. MEASUREMENTS: The relation between neonatal data from the Congenital Hypothyroidism (CH) screening and maternal thyroid determinants [TSH, FT4 and thyroid peroxidase (TPO)-Ab] assessed at 12-, 24- and 36-week gestation. RESULTS: Boys have lower screening TT4 levels and their mothers have higher TSH levels at 24- and 36-week gestation. Higher maternal TSH levels (>97·5th percentile, as defined in 810 women without TPO-Ab at 12 weeks) at one or more times during pregnancy (O.R: 2·26, 95% CI: 1·20-4·29) and lower gestational age (O.R: 1·22, 95% CI: 1·05-1·41) are independently related to lower screening TT4 levels. CONCLUSIONS: Maternal thyroid function during gestation is related to neonatal TT4 at screening. The finding of both lower neonatal TT4 levels in boys and higher TSH levels in mothers carrying boys is worthy of further investigation, as both observations may be meaningfully related.

High thyrotrophin levels at end term increase the risk of breech presentation.

OBJECTIVE: To study the relationship between maternal thyrotrophin (TSH) and breech presentation at term. DESIGN: Combined data sets of two prospective studies to obtain adequate epidemiological power. PATIENTS: One thousand and fifty-eight healthy pregnant women (58 breech, 1000 cephalic) and 131 women who presented in breech at an obstetrical outpatient clinic. MEASUREMENTS: Maternal thyroid parameters [TSH, free thyroid hormone (FT4), thyroid peroxidase antibody (TPO-Ab)] and foetal presentation were assessed in both groups between 35 and 38 weeks gestation. Power calculations suggested that at least 148 breech cases were required. RESULTS: The characteristics of the women in breech in both samples were similar. Women in breech (n = 58 + 131) had significantly higher TSH (but not FT4) than those (n = 1000) with cephalic presentation (Mann-Whitney U-test, P = 0·003). Different cut-offs were used to define high TSH in the 916 TPO-Ab-negative women with cephalic presentation: the 90th, 95th and 97·5th percentiles were 2·4 mIU/l (n = 149), 2·7 mIU/l (n = 77) and 3·2 mIU/l (n = 37). The prevalence rates of breech presentation in these women were all higher compared to the prevalence of breech in women below these cut-offs (df = 1, P < 0·01). The relative risk of the 149 women with a TSH >90th percentile (>2·4 mIU/l) to present in breech was 1·82 (95% CI: 1·30-2·56). CONCLUSIONS: Women with high TSH at end term are at risk for breech presentation. Substantial evidence for a relation between breech presentation and neurodevelopmental delay exists. As high TSH during gestation has also been linked to poor neurodevelopment, the relation between breech presentation and poor neurodevelopment might be thyroid-related.

Maternal thyroid function during gestation is related to breech presentation at term.

OBJECTIVE: To study the relationship between suboptimal maternal thyroid function during gestation and breech presentation at term. DESIGN: Prospective follow-up study during three trimesters of gestation. PATIENTS: A total of 1058 Dutch Caucasian healthy pregnant women were prospectively followed from 12 weeks gestation until term (>or=37 weeks) delivery. MEASUREMENTS: Maternal thyroid parameters [TSH, free T4 (FT4) and auto-antibodies to thyroid peroxidase] were assessed at 12, 24 and 36 weeks gestation as well as foetal presentation at term. RESULTS: At term, 58 women (5.5%) presented in breech. Compared with women with foetuses in the cephalic position, those women who presented in breech at term had significantly higher TSH concentrations, but only at 36 weeks gestation (P = 0.007). No between group differences were obtained for FT4 level at any assessment. The prevalence of breech presentation in the subgroup of women with TSH >or= 2.5 mIU/l (90th percentile) at 36 weeks gestation was 11%, compared with 4.8% in the women with TSH < 2.50 mIU/l (P = 0.006). Women with TSH below the 5th percentile had no breech presentations. Breech position was significantly and independently related to high maternal TSH concentration (>or=2.5 mIU/l) at 36 weeks gestation (O.R.: 2.23, 95% CI: 1.14-4.39), but not at 12 and 24 weeks gestation. CONCLUSIONS: Women with TSH levels above 2.5 mIU/l during end gestation are at risk for breech presentation, and as such for obstetric complications.

Comorbidity, co-occurrence, continuum: What's in a name?

BACKGROUND: Comorbidity, co-occurrence and continuum are three terms used when referring to developmental problems such as Developmental Coordination Disorder (DCD), but they can be confusing and misleading. Further, the terms can be upsetting to parents, and are not always helpful in guiding the selection of clinical interventions. GOALS: The main purpose of this paper is to question some of the terminology we employ when referring to DCD and other developmental problems. A secondary purpose is to discuss some of the conceptual frameworks that have been proposed that attempt to address the issue of the interrelationships among developmental problems. APPROACH: The terminology is examined by first referring to the basic dictionary definitions. Second, data we have published that relate to the issues of co-occurrence and continuum are reviewed in light of the terminology questions. Finally, we review some alternative conceptual frameworks which more accurately describe the relationships among developmental problems. CONCLUSION: The term 'comorbidity' has limited relevance to developmental problems, and its use is questionable. In contrast, co-occurrence and continuum are more useful terms to use in regard to developmental problems. Concepts such as atypical brain development and minor neurological dysfunction provide some possible explanations for the increased levels of co-occurrence of developmental disorders in children who are more severely affected.

Intellectual and motor development of young adults with congenital hypothyroidism diagnosed by neonatal screening.

CONTEXT: Long-term follow-up data on cognitive and motor functioning in adult patients with congenital hypothyroidism, diagnosed by neonatal screening, are scarce. Hence, it is still unclear whether the frequently reported cognitive and motor deficits observed during childhood persist in adulthood. OBJECTIVE: The objective of this study was to examine cognitive and motor functioning in young adults with congenital hypothyroidism, born in the first 2 yr after the introduction of the Dutch neonatal screening program. DESIGN/SETTING/PATIENTS: Seventy patients were tested (mean age, 21.5 yr); 49 of them were previously tested at 9.5 yr. The median age at the start of treatment was 28 d (range, 4-293 d). Congenital hypothyroidism was classified as severe, moderate, or mild, according to pretreatment T(4) concentrations. MAIN OUTCOME MEASUREMENT: The main outcome measurement was the influence of the severity of congenital hypothyroidism and age at which T(4) supplementation was started on cognitive and motor outcome. RESULTS: Patients, particularly those with severe congenital hypothyroidism, had significantly higher (i.e. worse) motor scores (total score, 7.8; ball skills, 2.0; balance, 4.1) compared with controls (total score, 3.2; ball skills, 0.7; balance, 1.1), and lower full-scale (95.8), verbal (96.4), and performance (95.6) intelligence quotient (IQ) scores than the normal population. No significant change in IQ from childhood to adulthood was found, and for the majority of patients, motor score classification remained the same. The severity of congenital hypothyroidism, but not the starting day of treatment, was correlated with IQ and motor scores. CONCLUSIONS: It is concluded that the severity of congenital hypothyroidism, but not the timing of treatment initiation, is an important factor determining long-term cognitive and motor outcome. Clearly, detrimental effects on developmental outcome in patients with congenital hypothyroidism persist over time.

Exploring field vegetation reflectance as an indicator of soil contamination in river floodplains.

This study investigated the relation between vegetation reflectance and elevated concentrations of the metals Ni, Cd, Cu, Zn and Pb in river floodplain soils. High-resolution vegetation reflectance spectra in the visible to near-infrared (400-1350 nm) were obtained using a field radiometer. The relations were evaluated using simple linear regression in combination with two spectral vegetation indices: the Difference Vegetation Index (DVI) and the Red-Edge Position (REP). In addition, a multivariate regression approach using partial least squares (PLS) regression was adopted. The three methods achieved comparable results. The best R(2) values for the relation between metals concentrations and vegetation reflectance were obtained for grass vegetation and ranged from 0.50 to 0.73. Herbaceous species displayed a larger deviation from the established relationships, resulting in lower R(2) values and larger cross-validation errors. The results corroborate the potential of hyperspectral remote sensing to contribute to the survey of elevated metal concentrations in floodplain soils under grassland using the spectral response of the vegetation as an indicator. Additional constraints will, however, have to be taken into account, as results are resolution- and location-dependent.

Behavioural correlates of early-treated congenital hypothyroidism.

UNLABELLED: Parents' and teachers' ratings were used to evaluate the behavioural characteristics of children with early-treated congenital hypothyroidism (CH). Comparisons were made between 63 children with early-treated CH and 34 healthy controls at the ages of 7.5 and 9.5 y. Additional comparisons were made between the two largest CH subgroups (thyroid agenesis, thyroid dysgenesis) and controls. The most marked differences were found on the introversion cluster and the motor clumsiness scale within it. Children with CH, particularly those with thyroid agenesis, showed introversion and motor clumsiness rather than social negativity and inattention. It is suggested that this behavioural profile may well have its origins in the often-reported inefficient motor behaviour of these children. Results are discussed in the light of recent findings suggesting an association between thyroid hormone problems and attention deficit hyperactivity disorder. CONCLUSION: Early-treated CH is associated with introversion rather than with social negativity.

A procedure for incorporating spatial variability in ecological risk assessment of Dutch river floodplains.

Floodplain soils along the river Rhine in the Netherlands show a large spatial variability in pollutant concentrations. For an accurate ecological risk characterization of the river floodplains, this heterogeneity has to be included into the ecological risk assessment. In this paper a procedure is presented that incorporates spatial components of exposure into the risk assessment by linking geographical information systems (GIS) with models that estimate exposure for the most sensitive species of a floodplain. The procedure uses readily available site-specific data and is applicable to a wide range of locations and floodplain management scenarios. The procedure is applied to estimate exposure risks to metals for a typical foodweb in the Afferdensche and Deestsche Waarden floodplain along the river Waal, the main branch of the Rhine in the Netherands. Spatial variability of pollutants is quantified by overlaying appropriate topographic and soil maps resulting in the definition of homogeneous pollution units. Next to that, GIS is used to include foraging behavior of the exposed terrestrial organisms. Risk estimates from a probabilistic exposure model were used to construct site-specific risk maps for the floodplain. Based on these maps, recommendations for future management of the floodplain can be made that aim at both ecological rehabilitation and an optimal flood defense.

Timing variability in children with early-treated congenital hypothyroidism.

This study reports on central and peripheral determinants of timing variability in self-paced tapping by children with early-treated congenital hypothyroidism (CH). A theoretical model of the timing of repetitive movements developed by Wing and Kristofferson was applied to estimate the central timekeeper (clock) and peripheral implementation (motor delay) variances from the variability in the response intervals. Before it is diagnosed and treated, CH is known to affect proper development of the cerebellum. If this would affect the time-keeper function of the cerebellum, it should be reflected by an increased central clock variability rather than by an increased peripheral motor-delay variability in terms of the Wing and Kristofferson model. Results of 46 children with early-treated CH, differing in severity (21 severe, 25 mild), and 34 normal controls are reported. A refinement of the Wing and Kristofferson model is applied to estimate central clock and peripheral motor delay timing variability more precisely than has been done before. Results show that for children with early-treated CH the estimate of the motor delay variance is four times higher than for the controls, while the estimate of the clock variance does not differ between the groups. It is concluded that motor problems in early-treated CH are associated with peripheral rather than with central timing deficiencies.

Sustained attention problems in children with early treated congenital hypothyroidism.

Sustained attention was studied in 48 children with early treated congenital hypothyroidism and 35 healthy controls, using a computer-paced and a self-paced continuous performance task. The performance of the patients, particularly those in the low T4 group (38 patients with T4 levels < 50 nmol/l at neonatal screening), declined in the final stage of the computer-paced task, suggesting a problem in remaining attentive over time. The performance of all children declined in the first and improved in the final stage of the self-paced task. This pattern was most pronounced in the low T4 group, reflecting greater variability in their task performance over time, again indicating a problem in sustaining attention. No correlation was found between onset of treatment and sustained attention. The small size of the intermediate T4 group (10 patients with T4 levels > or = 50 nmol/l at neonatal screening) made the results more difficult to interpret and may have concealed a problem with sustained attention in this group.

Motor and cognitive development in children with congenital hypothyroidism: a long-term evaluation of the effects of neonatal treatment.

Although neonatal thyroid screening programs have been of value in preventing cerebral damage, it is still controversial whether patients with congenital hypothyroidism achieve normal motor and cognitive skills. We studied the motor and cognitive skills of 72 children with early-treated congenital hypothyroidism and 35 control subjects at the ages of 7 1/2 and 9 1/2 years. The relative influence of cause, blood thyroxine concentration at the time of screening, and age at the start of thyroxine replacement therapy on motor and cognitive development was investigated. Despite having received treatment at a mean age of 23 days, children with low neonatal thyroxine concentrations (< 50 nmol/L) at screening, particularly children with thyroid agenesis, had significant motor problems and borderline intelligence scores as late as 9 1/2 years of age. Balance and gross motor functions seemed to decline between 7 1/2 and 9 1/2 years of age, whereas language and memory functions seemed to be maintained. Significant correlations between the start of therapy and both motor scores and performance IQ scores at the age of 7 1/2 years in children with severe hypothyroidism show the importance of early treatment for these patients.

Identification of feline monocytes and neutrophils as effector cells in antibody-dependent cellular cytotoxicity: sequential analysis, using light microscopy, histochemistry, and scanning electron microscopy.

Feline monocytes and neutrophils functioned as effector cells in antibody-dependent cellular cytotoxicity (ADCC) against antibody-coated chicken erythrocytes. Using light microscopy, effector cell populations were identified in effector-target cell interactions, with further characterization of these identical individual effector cells by histochemical evaluations and scanning electron microscopy. Monocytes and neutrophils, but not lymphocytes, were observed attacking target cells. Carbonyl iron depletion of monocytes and neutrophils from peripheral blood leukocytes caused a marked reduction from a mean of 62% to 3.6% lysis in ADCC as measured by a 4-hour 51Cr release assay. Effector cells functioning in the ADCC reaction were visualized, using sequential analysis and light microscopy, histochemistry, and scanning electron microscopy.

Killer cells of feline leukemia virus- and feline sarcoma virus-infected transformed cells: the role of NK, ADCC, and in vitro generated cytotoxic cells.

Feline white blood cells (WBC) manifested a primary in vitro mixed lymphocyte tumor cell culture (MLTC) proliferative response to feline leukemia virus-feline sarcoma virus (FeLV-FeSV)-infected transformed target cells, which reached a peak at Day 15. Furthermore, primary in vitro MLTC cultures generated cytotoxic killer cells capable of killing a variety of targets in non-major histocompatibility gene complex restricted fashion, and effector cells were capable of killing targets introduced repeatedly into cultures over a 49-day period. The presence of feline fibrosarcoma (f-sarc) stimulators was the primary driving force for proliferation and generation of killing because exogenous IL-2 conditioned medium did not appreciably increase the yield of killer cells generated in vitro. WBC cultured without f-sarc stimulators with or without IL-2 supplementation also generated killer (K) cells but at a low level. The killer cell population was composed of approximately 50% lymphocytes and 50% monocytes. Cats had K cells functional in antibody-dependent cell-mediated cytotoxicity against FeLV-coated chicken red blood cells but not against any FeLV-FeSV-infected transformed targets tested. Natural killer (NK) cell activity to any targets tested was not found. Although no evidence was found for K or NK cell activity against FeLV-FeSV-infected transformed cells, feline WBC were readily able to generate killer cells in vitro and it is probable that this cell-mediated immune potential is functionally important in vivo.

Termination of pseudopregnancy by administration of prostaglandin F2alpha and termination of early pregnancy by administration of prostaglandin F2alpha or colchicine or by removal of embryo in mares.

At day 24 of gestation, pregnant mares were allotted to 1 of 5 treatment groups (3 to 5 mares/group): group A--nontreated controls; group B--intraembryonic injection of 4 mg of colchicine on day 24; group C--removal of embryo on day 24; group D--subcutaneous injection of 1.25 mg of prostaglandin F2alpha (PGF2alpha) on day 32; and group E--removal of embryo on day 24 and subcutaneous injection of PGF2alpha on day 32. In all mares treated with colchicine (group B), the fetal bulge was absent within 2 days. The interval from injection of colchicine to onset of estrus was very short (mean, 4 days). These results indicated that treatment with colchicine was lethal to the 24-day embryo, and pseudopregnancy did not occur. Surgical removal of the embryo (group C) resulted in pseudopregnancy characterized by a prolonged interval from treatment to return to estrus (mean, greater than 31 days), prolonged production of progesterone, and prolonged maintenance of tense uterine and cervical tone. The interval from treatment to ovulatory estrus was longer (P less than 0.05) for group C mares than for group B mares. The mean interval from treatment to complete loss of tense tubular uterine tone was not significantly different between group A pregnant controls (28.3 days) and group C pseudopregnant mares (30 days). Treatment of pregnant mares (group D) with a single injection of PGF2alpha on day 32 resulted in loss of pregnancy in 4 of 4 mares within 2 to 5 days, and in all group D mares a large decrease in progesterone concentration occurred on day 33, 34, or 35. Although subsequent reproductive activity was variable, all group D mares rapidly lost the tense uterine and cervical tone characteristic of early pregnancy. These results indicated that a single subcutaneous injection of 1.25 mg of PGF2alpha caused loss of pregnancy, and pseudopregnancy did not occur. Treatment of group E mares, which had been made pseudopregnant by removal of embryo, with 1.25 mg of PGF2alpha resulted in termination of pseudopregnancy in 5 of 5 mares. All group E mares returned to estrus within 2 to 5 days after treatment, and progesterone concentration decreased (P less than 0.05) within 2 days after treatment. There was no significant difference in loss of tense tubular uterine or cervical tone between pregnant (group D) and pseudopregnant (group E) mares after PGF2alpha treatment.

Effect of photoperiod on reproductive activity and hair in mares.

The effects of photoperiod on reproductive activity and hair changes in pony mares were studied in 2 experiments. In experiment I, the effect of a fixed daily photoperiod on the onset of the breeding season was studied in 36 mares from Nov 13, 1973, to June 13, 1974. The 4 treatment groups were as follows: daily photoperiod equivalent to the normal day length (control group); constant light 24 hours a day with no dark (L24:D0 group); 16-hour daily photoperiod with 8 hours of dark (L16:D8 group); and 9-hour daily photoperiod with 15 hours of dark (L9:D15 group). The intervals from beginning of experiment to 1st ovulation of breeding season, to shedding of hair in tufts, and to appearance of a smooth coat were shorter (P less than 0.05) for L16:D8 group (107.1 +/- 11.1, 56.0 +/- 0, and 145.8 +/- 4.0 days, respectively) than for control, L24:D0, and L9:D15 groups and were shorter (P less than 0.05) for L24:D0 group (less than 156.1 +/- 12.2, 99.5 +/- 9.5, and 173.9 +/- 9.9 days, respectively) than for control group (192.1 +/- 3.3, 134.9 +/- 8.9, and 205.0 +/- 0 days, respectively) or L9:D15 group (less than 200.3 +/- 5,8, 150.6 +/- 12.9, and 201.7 +/- 3.3 days, respectively). These intervals were not significantly different between the control group and the L9:D15 group, but fewer (P less than 0.05) mares in the L9:D15 group had at least 1 ovulation by termination of the project. In experiment II, the effect of photoperiod on onset of anestrus was studied in 3 groups of 7 mares each. Mares in group A, as part of a previous experiment, were induced to enter the breeding season earlier than normal by a gradual increase in daily photoperiod beginning on Oct 13, 1972. From Feb 16, 1973, to June 22, 1973, group A mares were maintained at a fixed daily photoperiod of 15 hours 23 minutes. Mares in group B, as part of a previous experiment, were kept under environmental conditions simulating normal conditions in southern Wisconsin. On June 22, 1973 (beginning of the present experiment), the following treatments began: groups A and B were exposed to natural day length. In addition, 7 mares (group C) were allotted from a band of mares that had been exposed to natural day length and were exposed to 15-hour 23-minute daily photoperiod from the beginning of the present experiment (June 22, 1973) to the end (June 22, 1974). The interval to onset of anestrus was longer (P less than 0.05) for group C mares (234.6 +/- 35 days) than for group B mares (133.6 +/- 16.5 days). Significant difference did not exist between group A (144.0 +/- 45.9 days) and group B. A fixed daily photoperiod of 16 or 24 hours induced early onset of the breeding season and early shedding of hair, with development of a smooth coat. A photoperiod of 9 hours retarded the onset of the breeding season. Mares induced to begin the breeding season earlier than normal did not become anestrous earlier than normal. Mares kept on a long daily photoperiod in the fall became anestrous later than normal.

Effects of artificial light on the oestrous cycle of the mare.

Two groups, each of seven pony mares, were maintained from 17 October to 15 February (120 days) in the University Biotron where temperature and daily photoperiod were regulated to simulate normal conditions for that period (control group) or those normally applicable from 1 March to 1 July (treated group). Follicular growth, ovulation rate and oestrous behaviour were determined daily by rectal palpation, and by teasing with a stallion. By Day 69 of treatment, all ovarian end-points (number of follicles greater than 10 mm, number of follicles greater than 20 mm, average follicle diameter and diameter of the largest follicle) were significantly greater in treated than control mares. Oestrous behaviour was evident in all the mares in the treated group, but was not recorded in any of the control group mares; two of the treated mares ovulated. After removal from the environmental control chambers, the experimental and control mares first ovulated on an average of 147 days and 227-6 days, respectively, after the beginning of the project. Mares in both groups cycled regularly after the first ovulation and were in anoestrus again at about the same time in the following winter.