Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “conception”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 649 records · Page 36Linked to original sources
PubMed2006

Estimation of solids loadings to rainfall-runoff unit operations using a unit pollutograph concept for source area watersheds.

Source area watershed in the built environment deliver significant loads of solids and constituents such as metals, organics and phosphorus associated with solids. The ability to model the mass delivery process of solids in small urban watersheds is essential for advancement of rainfall-runoff quantity and quality control design in the built environment. In this study the hydrologic concepts of the unit hydrograph (UH) and instantaneous unit hydrograph (IUH) were used to support the concepts of a unit pollutograph (UP) and an instantaneous unit pollutograph (IUP). These latter two concepts were developed as analogous concepts for estimation of solids mass transport loading as a pollutograph from source area watersheds. Relationships between solids mass and hydrologic volume were based on relationships that expressed either a first-order or zero-order relationship between solids mass and volumetric transport. The resulting concepts were applied to historical rainfall-runoff events where the hydrologic and water quality measurements had been conducted. From this development a site mean IUH and IUP determined from the rainfall-runoff record and water quality data, the corresponding site mean UH and UP were developed for solids. The hydrographs and solid pollutographs generated by convolution of the UH and UP compared well with measurements, indicating the feasibility of the concept.

Drainage, Sanitary↗
PubMed2001

Effect of lameness on the calving-to-conception interval in dairy cows.

OBJECTIVE: To examine the relationship between lameness and the duration of the interval from calving to subsequent conception in lactating dairy cows. DESIGN: Cohort study. ANIMALS: 837 dairy cows. PROCEDURE: Cows affected with lameness were classified into 1 of 4 groups on the basis of types of disease or lesions observed, including foot rot, papillomatous digital dermatitis, claw lesions, or multiple lesions. Cows not affected with lameness were classified as healthy. Time from calving to conception was compared between lame cows and healthy cows. RESULTS: 254 (30%) cows were affected with lameness during lactation. Most lame cows (59%) had claw lesions. Lame cows with claw lesions were 0.52 times as likely to conceive as healthy cows. Median time to conception was 40 days longer in lame cows with claw lesions, compared with healthy cows. Number of breedings per conception for lame cows with claw lesions was significantly higher than that for healthy cows. CONCLUSION AND CLINICAL RELEVANCE: Claw lesions were the most important cause of lameness, impairing reproductive performance in dairy cows, as indicated by a higher incidence of affected cows and a greater time from calving to conception and a higher number of breedings required per conception, compared with healthy cows.

Animals↗
PubMed2005

Comparison of the calving-to-conception interval in dairy cows with different degrees of lameness during the prebreeding postpartum period.

OBJECTIVE: To compare calving-to-conception intervals among cows classified as nonlame, moderately lame, or lame during the prebreeding postpartum period and to examine the relationship between severity of lameness and time to conception in cows that were classified as lame. DESIGN: Longitudinal study. ANIMALS: 499 Holstein cows. PROCEDURE: Cows in the prebreeding postpartum period were classified as nonlame, moderately lame, or lame by use of a 6-point locomotion scoring system. Time to conception (days) was compared among cows. A low, medium, or high cumulative locomotion score was assigned to lame cows, and time to conception among those cows was compared. Cows classified as lame were examined on a tilt table for diagnosis and treatment of lameness. RESULTS: 154 (31%), 214 (43%), and 131 (26%) cows were classified as nonlame, moderately lame, and lame, respectively. Most cows classified as lame had laminitis (54%) or disorders of the claw (33%). Median time to conception was 36 to 50 days longer in lame cows than in nonlame cows. Among lame cows, the median time to conception was 66 days longer in cows with high cumulative locomotion scores than in cows with low scores. CONCLUSION AND CLINICAL RELEVANCE: Nonlame cows became pregnant more quickly than lame cows. Lame cows with low cumulative locomotion scores during the prebreeding postpartum period became pregnant sooner than lame cows with high scores. Early diagnosis and intervention may mitigate the effects of lameness and improve reproductive performance in lame dairy cows.

Animals↗
PubMed1989

Conception rate in Bos taurus and Bos indicus crossbred heifers after postweaning energy manipulation and synchronization of estrus with melengestrol acetate and fenprostalene.

Conception rate in heifers after synchronization of estrus with melengestrol acetate (MGA) and fenprostalene (a prostaglandin F2 alpha analogue; PGF) was determined in pubertal Bos taurus and Bos indicus crossbred yearling heifers. Angus x Hereford (AH, n = 137) and Brahman x Hereford (BH, n = 97) heifers were sorted by body weight after weaning into light (LW) and heavy (HW) weight blocks. Heifers were assigned by age to diets to reach a target weight of 55% (LE) or 65% (HE) of their projected mature weight by the start of breeding. Heifers that exhibited estrus and had serum progesterone greater than or equal to 1 ng/ml (0 or 10 d before estrous synchronization treatment) were assigned randomly within breed and nutritional groups to either an estrous synchronization (S) or control (C) group. Heifers in the S group were fed .5 mg of MGA for 7 d and injected s.c. with 2 mg PGF on d 7 of MGA. All heifers were inseminated 12 h after first detected estrus. A greater proportion of AH (P less than .01) than of BH heifers were in estrus within 6 d after PGF, and more S heifers than C heifers (P less than .01) were in estrus. Conception rate at first service was proportionately higher (P less than .001) in AH than in BH heifers and lower (P less than .02) in S than in C heifers. There was a breed x energy level interaction (P less than .01) for conception rate at first service. Stage of the estrous cycle at the time treatment with MGA was initiated influenced (P less than .05) conception rate at first service in the S, AH heifers, with lower conception rates among heifers beginning treatment late in their estrous cycles (greater than or equal to d 12). Pregnancy rates after 21 d were higher (P less than .01) in AH than in BH heifers and higher (P less than .01) in HW than in LW heifers. More HE than LE heifers (P less than .02), and more AH than BH heifers were pregnant after 45 d. Pregnancy rates at the end of 21 d were higher among HE, BH heifers than among LE contemporaries. A higher (P less than .02) percentage of HE, HW, BH heifers were pregnant at the end of 45 d compared with other BH groups. Results indicated that a 7-d MGA-PGF treatment reduced conception rates at first service in pubertal yearling heifers. Pregnancy rate was affected by prebreeding nutrition in BH yearling heifers at the end of 45 d.

Administration, Oral↗
PubMed1989

Conception rates in early postpartum ewes bred naturally or by intrauterine insemination.

Ewes were treated with a medroxyprogesterone acetate (MAP) sponge for 8 d followed, at sponge removal, with 500 IU pregnant mare serum gonadotropin (PMSG) at d 30, 40 or 50 (d 0 = lambing) to induce estrus. Dry and lactating ewes were divided into equal numbers at each postpartum day and bred at estrus. Conception rates and number of accessory sperm were determined by flushing the oviducts 3 d after mating and examining the recovered ova. There was no effect (P greater than .05) of lactational status on conception rates. Conception rates increased (P less than .05) from d 30 (10%) to d 40 (45%) and from d 40 to d 50 (80%). There were fewer (P less than .05) ova with accessory sperm (5/26) in d-30 ewes compared with d-40 (10/27) or d-50 (12/24) ewes. In Exp. 2, ewes were assigned to two groups after receiving PMSG on d 30: 1) mated naturally or 2) inseminated during laparotomy near the uterotubal junction (UTJ). Dry and lactating ewes were divided evenly within each of the two treatments. Oviducts were flushed and ova were examined for cleavage. The conception rate was 60% in ewes that were inseminated in the UTJ vs 10% in ewes mated to rams (P less than .05). Lactational status had no effect on results. In conclusion, conception rates in postpartum ewes treated with MAP sponge and PMSG increased from postpartum d 30 to d 50 with natural breeding, and d-30 conception rates were increased over natural mating by insemination into the uterine horn near the UTJ.

Administration, Intravaginal↗
PubMedDate not supplied

Theoretical considerations on medical concept representation.

Concepts are seen as building elements of more compositional information objects in medicine. Consequently, representation of medical concepts plays a critical role in any information system. The authors present some of the key problems which need solution, such as definition of medical domain, analysis of internal structure, different subsets of medical concepts, and the problem of the 'elementary' concepts. As a result of these considerations we can conclude that the domain of medical concepts can hardly be delimited and consists of different subsets. These subsets need different representation methods according to their different nature. Some of these subsets have a hierarchic structure. In those one can find sometimes multiple hierarchies. We suggest avoiding multiple hierarchies in concept systems by the introduction of new dimensions.

Decision Support Techniques↗
PubMed2004

Effects of milk urea nitrogen and other factors on probability of conception of dairy cows.

The objective of this study was to evaluate the relationships between milk urea nitrogen (MUN) and other factors and the probability of conception in dairy cows. Data were retrieved from the Lancaster Dairy Herd Improvement Association (DHIA). A total of 713 dairy herds and 10,271 dairy cows were included in the study. Logistic regression was used to determine the within-herd effects of MUN, milk production, lactation number, and breeding season on the probability of conception for each of 3 services. Within herds, MUN displayed a slight negative association with probability of conception at first service. For example, there was a 2- to 4-percentage unit decrease in conception rate at first service with a 10-mg/dL increase in MUN. In among-herd regression analysis, there was no effect of MUN on probability of conception. These results suggest that MUN may be related to conditions affecting reproduction of individual cows within a herd. Diet formulation usually would affect MUN equally among all cows at a similar stage of lactation in a herd. Because there was no effect of MUN among herds, diet formulation did not appear to affect conception rate.

Animals↗
PubMed1983

Estrous intensity and conception rates in Holsteins.

During 34 mo, 732 inseminations were evaluated in Holstein cows and heifers of breeding age. Females were submitted for insemination after detection of either 1) standing estrus, 2) mounting activity, or 3) other subtle symptoms of estrus (clear mucus, general appearance of genitalia or tailhead, and excessive vocalization). Conception rates were similar following standing estrus and mounting activity (50 versus 46%). Although higher conception rates occurred following standing or mounting activity than after detection of subtle estrous symptoms, one of three inseminations resulted in conception after insemination in the latter group. Clear mucus in half of the females upon cervical manipulation at insemination was associated with higher conception. Service number, age, and maximum ambient temperature on day of insemination also affected conception rates. Methods of thawing semen, ease of cervix penetration at insemination, service sire, inseminator, and time of estrous detection and insemination had little effect on fertility. Acceptable conception rates were achieved with more liberal interpretation of estrous symptoms.

Age Factors↗
PubMed1984

Effects of production, season, age of cow, days dry, and days in milk on conception to first service in large commercial dairy herds.

Effects of management and environmental factors on reproductive performance were evaluated as part of a fertility experiment in four large commercial dairy herds. The herds were selected because they utilized routine herd health programs, kept complete reproduction records on all cows, were enrolled in Dairy Herd Improvement, and would follow the protocol of the experiment. Only data from first services following parturition were utilized, and conception was determined by rectal palpation. Information on over 2800 experimental breedings was collected during 13 mo. Percentage conception to first service was not affected by milk production during current or previous lactations. However, cows with higher production during current or previous lactations. However, cows with higher production during current or previous lactation had longer intervals to first service. Previous days dry did not affect conception or interval to first service significantly. Conception was less for cows with less than 50 days to first service (32%) than for cows with over 50 days to first service (49 to 57%). No differences were found among 10-day intervals to first service of over 50 days. Cows in third and later lactation had lower reproductive performance than cows in first or second lactation. Month of breeding did not affect conception significantly but did affect interval to first service. However, no seasonal trends were apparent. Differences among herds were significant for both conception and interval to first service.

Age Factors↗
PubMed1997

Relationship between body condition scores and conception at first artificial insemination in a large dairy herd of high yielding Holstein cows.

This study investigated the relationship between changes in body condition during the dry period and early lactation and conception to first postpartum AI. Holstein cows (n = 720) on a commercial dairy farm were scored weekly for body condition beginning at dry-off and continuing until first AI. Occurrence of postpartum diseases was recorded. A multiple logistic regression model was a significant predictor of the success or failure of conception for multiparous cows, but not for primiparous cows. Principal component analysis reduced collinearity among independent variables and allowed the variables to be ranked based on their contribution to the interval from first AI to conception. The top three ranking variables were lactation number, milk yield at 120 d of lactation, and change in body condition score between parturition and wk 4 of lactation. Increased milk yield at 120 d of lactation was associated with an increased likelihood of conception, and decreased body condition during the 1st mo of lactation was associated with a decreased likelihood of conception. Health problems were less associated with conception than were body condition or milk yield in this herd. Body condition during the dry period and during the first 30 d of lactation is an important tool to identify cows at risk for failure to conceive at first AI.

Adipose Tissue↗
PubMed2004

A cross-culturally standardized set of pictures for younger and older adults: American and Chinese norms for name agreement, concept agreement, and familiarity.

The present study presents normative measures for 260 line drawings of everyday objects, found in Snodgrass and Vanderwart (1980), viewed by individuals in China and the United States. Within each cultural group, name agreement, concept agreement, and familiarity measures were obtained separately for younger adults and older adults. For a subset of 57 pictures (22%), there was equivalence in both name agreement and concept agreement, and for an additional subset of 29 pictures (11%), there was nonequivalent name agreement but equivalent concept agreement, across all culture-by-age groups. The data indicate substantial differences across culture-by-age groups in name agreement percentages and number of distinct name responses provided. We discovered significant differences between older and younger American adults in both name agreement percentages (67 pictures, or 26%) and concept agreement percentages (44 pictures, or 17%). Written naming responses collected for the entire set of Snodgrass and Vanderwart pictures showed shifts in both naming and concept agreement percentages over the intervening decades: Although correlations in name agreement were strong (r = .71, p < .001) between our younger American samples and those of Snodgrass and Vanderwart, name agreement percentages have changed for a substantial proportion (33%) of the 260 pictures; moreover, 63% of the stimuli for which Snodgrass and Vanderwart reported concept agreement now appear to differ. We provide comprehensive comparison statistics and tests for both the present study and prior ones, finding differences across numerous item-level measures. The corpus of data suggests that substantial differences in all measures can be found across age as well as culture, so that unequivocal conclusions with respect to cross-cultural or age-related differences in cognition can be made only when appropriate stimuli are selected for studies. Data for all 260 pictures, for each of the four groups, and all supporting materials and tests are freely archived at http://agingmind.cns.uiuc.edu/Pict_Norms. The full set of these norms may be downloaded from www.psychonomic.org/archive/.

Adolescent↗
PubMed2005

[Concept analysis of endotracheal suctioning (ETS)].

PURPOSE: Concept analysis was performed on the behavioral concept of endotracheal suctioning (ETS), to identify the goal, to develop a standardized clinical protocol, to identify the antecedents and consequences, and to differentiate the improper use of ETS. METHOD: Walker & Avant's concept analysis was employed using clinical guidelines, books and review articles in which the procedures of ETS were written in detail and published in Pubmed within the last 20 years. RESULT: The macro-goal of ETS was to remove accumulated respiratory secretions. Three defining attributes of ETS were identified; catheter, suctioning and asepsis. Each attribute involved empirical referents, such as the size and depth of the catheter, the suction pressure, duration and method for suctioning. The antecedents of ETS were identical to the clinical evidences for the need of ETS such as the nursing assessment data. The consequences of ETS serve as an evaluation criteria on the effects of ETS based on the goal of ETS. CONCLUSION: The concept analysis of ETS demonstrates an example of considering a specific nursing protocol of ETS as a behavioral concept, applying concept analysis to it to identify it's key behavioral components as defining attributes and empirical referents and then developing and applying the standard ETS protocol.

Humans↗
PubMed2004

Are illness concepts a powerful predictor of adherence to prophylactic treatment in bipolar disorder?

BACKGROUND: Predicting and preventing premature discontinuation of medication would substantially improve prophylactic treatment of bipolar disorder. Patients' concepts regarding illness proved to have an impact on noncompliance in a retrospective study of patients with affective or schizoaffective illness treated with lithium. The present study is the first to prospectively investigate the influence of illness concepts on adherence of bipolar patients to different medications. METHOD: 171 bipolar patients (DSM-IV) were randomly assigned to receive either lithium (N = 86) or carbamazepine (N = 85) and observed for a maintenance period of 2.5 years (Multi-center Study of Affective and Schizoaffective Psychoses). The total score and 7 dimensions of illness concepts and treatment expectations of the Illness Concept Scale (ICS) were calculated for 141 patients with completed questionnaires and used to predict time to dropout (Cox regression). Analyses were corroborated by further multivariate analyses with sex, age, and premorbid personality as covariates. RESULTS: With lithium treatment, but not carbamazepine treatment, the total ICS score at study entry was associated with a longer time to study dropout (p =.001 and p =.224, respectively). The relevant ICS subscales affecting time to dropout in patients treated with lithium were trust in medication, trust in the treating physician, and absence of negative treatment expectations. Multivariate analyses suggested that the impact of these variables on adherence to lithium was largely independent of sociodemographic, clinical, and psychological variables. Our data indicate that the stronger impact of illness concepts with lithium as compared with carbamazepine treatment might be related to the drugs' different side effect profiles. CONCLUSION: As trust in drug treatment and trust in the treating physician had a clear impact on adherence to prophylactic lithium, patients' illness concepts and treatment expectations might be promising targets for psychoeducation and psychotherapy in the treatment of bipolar disorder.

Adult↗
PubMed2004

Role of sonography in the diagnosis of retained products of conception.

OBJECTIVE: To present our experience with clinical and sonographic diagnosis of retained products of conception and to evaluate its correlation with histopathologic findings. METHODS: This was a retrospective study on 156 patients admitted for retained products of conception. Women were referred because of 1 or more of the following: abdominal pain, bleeding, and fever. The status of the cervix was evaluated by bimanual examination. The diagnosis of retained products of conception was made when a sonographic finding of hyperechoic or hypoechoic material was seen in any part of the uterine cavity or the presence of a thickened endometrial stripe greater than 8 mm and an irregular interface between the endometrium and myometrium was found. One hundred twenty-one women (77.6%) were admitted after dilation and curettage for abortion, and 35 (22.4%) were admitted after spontaneous labor. RESULTS: Histopathologic reports confirmed the diagnosis of retained products of conception in 86 (71%) of 121 women in the postabortion group and in 17 (48.5%) of 35 women in the postpartum group. The overall false-positive rate for sonographic diagnosis was 34%. For women after abortion and after delivery, the false-positive rates were 28.9% and 51.5%, respectively. CONCLUSIONS: Reliance on common signs and symptoms to diagnose retained products of conception as well as the use of sonography is associated with an unacceptably high false-positive rate, mainly after delivery. A more conservative approach to the treatment of retained products of conception is suggested.

Abortion, Incomplete↗
PubMed1976

[The concept of health and disease].

1. The author reviews some current concepts concerning the definitions and uses of the concepts of health and illness. Starting from the definitions in Psychiatry, "normality" is considered from the statistic, the normative and the clinical standpoints, and as a part of a continuum stretching from health to illness. Several approaches are analyzed, among which Wittaker's, who sets forth the following indicators of normality: a) self-knowledge; b) self-esteem; c) self-security; d) capacity for giving and receiving affection; e) satisfaction of corporal needs; f) productivity and capacity for happiness; g) lack of tensions and of hipersensitivity. 2. The concept of illness as an operative concept is also analyzed, leading to the following statements: a) it is inexistent in non-biological sciences; b) it appears in social sciences only through extrapolation; c) in medicine it means the breacking of homeosthasis; d) in psychology and dynamic psychiatry it means the abnormal stressing of normal mechanisms, common to all persons. 3. The concept of health as equilibrium is also analyzed, with the following precisions: a) equilibrium is defined within a system as affecting the whole of it, and implying transformation and self-regulation; b) homeosthasis is a case of equilibrium for steady complex systems; c) adaptation is the maintenance of equilibrium when there are exchanges with the evironment. 4. Finally, those concepts are applied to mental illness and its limits, and the following criteria are set forth: a) amount of anguish; b) depression related to its motives, intensity, persistence and frequency; c) regression to previous development stages; d) use of defense mechanisms in an inadequate or stereotyped way.

Adaptation, Biological↗
PubMed2001

The organizer concept and modern embryology: Anglo-American perspectives.

This paper analyses the origins of the Spemann-Mangold organizer concept of 1924 in relation to his earlier background and concepts. It traces the consequences and fate of the organizer, and related concepts (embryonic induction, gradients, fields) through subsequent phases in the evolution of developmental biology up to the present, primarily from a UK perspective, but also in the USA. The origins of Wolpert's concept of positional information of around 1970 are analysed; this markedly different model of embryogenesis effectively took the place of the organizer, following on from a generally assumed out-datedness of the corpus of Spemann's data and concepts. Explanations in terms of historical forces are suggested; events are seen as a historical causal chain. A crucial factor appears to have been the long-term neglect of morphogenetic cell movement as an integral component of an adequate induction-based model. The paper discusses the general inter-relation of history and science, and particularly the implications for current scientific practice, including the potential for conceptual distortions due to historical factors. It is argued that historical considerations need to be included as part of the use and critical assessment of basic concepts in science.

Animals↗
PubMed2001

Methods for exploring the semantics of the relationships between co-occurring UMLS concepts.

OBJECTIVE: To characterize the relationships among UMLS concepts that co-occur as MeSH descriptors in MEDLINE citations (1990-1999). DESIGN: 18,485 UMLS concepts involved in 7,928,608 directed pairs of co-occurring concepts were studied. For each directed pair of concepts C1-C2: (i) the "family" of C1 was built, using the UMLS Metathesaurus, and we tested whether or not C2 belonged to C1's family; (ii) we used the semantic categorization of Metathesaurus concepts through the UMLS Semantic Network and Semantic Groups to represent the semantics of the relationships between C1 and C2. RESULTS: In 6.5% of the directed pairs, the co-occurring concept C2 was found within the "family" of C1. Detailed results are given. The most frequent co-occurrences involved "Chemicals and Drugs" and "Chemicals and Drugs", as well as "Disorders" and "Chemicals and Drugs". DISCUSSION: This work takes advantage of both symbolic and statistical information represented in the UMLS, and analyzes their overlap. Further research is suggested.

MEDLINE↗
PubMed2002

Does cigarette smoking increase time to conception?

Data are reported on the relationship between cigarette smoking and other health-related behaviours and time to conception in a population-based sample of women who acted as a control group in a case-control study of twinning. Women who continued to smoke close to the time of conception took significantly longer to become pregnant than women who never smoked or stopped smoking before the year during which they attempted to conceive. A hierarchical regression analysis performed on time-to-conception data in women who continued to smoke in the year before conception provided weak evidence for a dose-response relationship between time to conception and number of cigarettes smoked per day. No significant relationships were found between time to conception and other health-related behaviours.

Adult↗