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1.
Trials ; 18(1): 434, 2017 09 20.
Article in English | MEDLINE | ID: mdl-28931404

ABSTRACT

BACKGROUND: Rates of cesarean delivery are continuously increasing in industrialized countries, with repeated cesarean accounting for about a third of all cesareans. Women who have undergone a first cesarean are facing a difficult choice for their next pregnancy, i.e.: (1) to plan for a second cesarean delivery, associated with higher risk of maternal complications than vaginal delivery; or (b) to have a trial of labor (TOL) with the aim to achieve a vaginal birth after cesarean (VBAC) and to accept a significant, but rare, risk of uterine rupture and its related maternal and neonatal complications. The objective of this trial is to assess whether a multifaceted intervention would reduce the rate of major perinatal morbidity among women with one prior cesarean. METHODS/DESIGN: The study is a stratified, non-blinded, cluster-randomized, parallel-group trial of a multifaceted intervention. Hospitals in Quebec are the units of randomization and women are the units of analysis. As depicted in Figure 1, the study includes a 1-year pre-intervention period (baseline), a 5-month implementation period, and a 2-year intervention period. At the end of the baseline period, 20 hospitals will be allocated to the intervention group and 20 to the control group, using a randomization stratified by level of care. Medical records will be used to collect data before and during the intervention period. Primary outcome is the rate of a composite of major perinatal morbidities measured during the intervention period. Secondary outcomes include major and minor maternal morbidity; minor perinatal morbidity; and TOL and VBAC rate. The effect of the intervention will be assessed using the multivariable generalized-estimating-equations extension of logistic regression. The evaluation will include subgroup analyses for preterm and term birth, and a cost-effectiveness analysis. DISCUSSION: The intervention is designed to facilitate: (1) women's decision-making process, using a decision analysis tool (DAT), (2) an estimate of uterine rupture risk during TOL using ultrasound evaluation of low-uterine segment thickness, (3) an estimate of chance of TOL success, using a validated prediction tool, and (4) the implementation of best practices for intrapartum management. TRIAL REGISTRATION: Current Controlled Trials, ID: ISRCTN15346559 . Registered on 20 August 2015.


Subject(s)
Cesarean Section, Repeat , Decision Support Techniques , Maternal Health , Pregnancy Outcome , Vaginal Birth after Cesarean , Cesarean Section, Repeat/adverse effects , Cesarean Section, Repeat/economics , Choice Behavior , Clinical Decision-Making , Clinical Protocols , Cost-Benefit Analysis , Female , Health Care Costs , Humans , Logistic Models , Multivariate Analysis , Nomograms , Patient Participation , Predictive Value of Tests , Pregnancy , Premature Birth/etiology , Quebec , Research Design , Risk Factors , Term Birth , Time Factors , Trial of Labor , Ultrasonography , Uterine Rupture/diagnostic imaging , Uterine Rupture/etiology , Vaginal Birth after Cesarean/adverse effects , Vaginal Birth after Cesarean/economics
2.
Health Educ Res ; 31(5): 587-602, 2016 10.
Article in English | MEDLINE | ID: mdl-27516095

ABSTRACT

Schools can play an important role in health promotion mainly by improving students' health literacy, behaviors and academic achievements. School-based health promotion can be particularly valuable in developing countries facing the challenges of low health literacy and high burden of disease. We conducted a scoping review of the published literature focusing on school-based interventions for health promotion and their impact in developing countries. We included 30 studies meeting specific criteria: (i) studies mainly targeted school going children or adolescents; (ii) admissible designs were randomized controlled trials, controlled before-after studies or interrupted time series; (iii) studies included at least one measure of impact and (iv) were primary studies or systematic reviews. We found that school-based interventions can be classified in two main categories: those targeting individual determinants of health such as knowledge, skills and health behaviors and those targeting environmental determinants such as the social and physical environment at the school, family and community level. Findings suggest that a comprehensive approach addressing both individual and environmental determinants can induce long-term behavior change and significantly improve health and educational outcomes. We highlight the need for further study of the long-term impact of school-based interventions on health outcomes in developing countries.


Subject(s)
Environment , Health Knowledge, Attitudes, Practice , Program Evaluation/methods , School Health Services/organization & administration , Adolescent , Child , Developing Countries , Humans
3.
J Thromb Haemost ; 9(12): 2397-405, 2011 Dec.
Article in English | MEDLINE | ID: mdl-21951970

ABSTRACT

BACKGROUND: Few studies have evaluated the long-term economic consequences of deep vein thrombosis (DVT). None of them have incorporated prospectively collected clinical data to ensure accurate identification of incident cases of DVT and DVT-related health outcomes of interest, such as post-thrombotic syndrome (PTS). OBJECTIVES: To prospectively quantify medical and non-medical resource use and costs related to DVT during 2 years following diagnosis, and to identify clinical determinants of costs. METHODS: Three hundred and fifty-five consecutive patients with acute DVT were recruited at seven Canadian hospital centers. Resource use and cost information were retrieved from three sources: weekly patient-completed cost diaries, nurse-completed case report forms, and the Quebec provincial administrative healthcare database (RAMQ). RESULTS: The rate of DVT-related hospitalization was 3.5 per 100 patient-years (95% confidence interval [CI] 2.2-4.9). Patients reported a mean (standard deviation) of 15.0 (14.5) physician visits and 0.7 (1.2) other healthcare professional visits. The average cost of DVT was $5180 (95% CI $4344-6017) in Canadian dollars, with 51.6% of costs being attributable to non-medical resource use. Multivariate analysis identified four independent predictors of costs: concomitant pulmonary embolism (relative increase in cost [RIC] 3.16; 95% CI 2.18-4.58), unprovoked DVT (RIC 1.65; 95% CI 1.28-2.13), development of PTS during follow-up (RIC 1.35; 95% CI 1.05-1.74), and management of DVT in the inpatient setting (RIC 1.79; 95% CI 1.33-2.40). CONCLUSIONS: The economic burden of DVT is substantial. The use of measures to prevent the occurrence of PTS and favoring outpatient care of DVT has the potential to diminish costs.


Subject(s)
Cost of Illness , Venous Thrombosis/economics , Adult , Aged , Canada , Female , Health Care Rationing , Humans , Male , Middle Aged , Prospective Studies
5.
Int J STD AIDS ; 21(12): 789-96, 2010 Dec.
Article in English | MEDLINE | ID: mdl-21297084

ABSTRACT

Although the Central American HIV epidemic is concentrated in high-risk groups, HIV incidence is increasing in young women. From 2005 to 2007, we conducted a cross-sectional study of pregnant women in a large public hospital and an HIV clinic in Guatemala City to describe risk factors for HIV infection and inform prevention strategies. For 4629 consenting patients, HIV status was laboratory-confirmed and participant characteristics were assessed by interviewer-administered questionnaires. Lifetime number of sexual partners ranged from 1 to 99, with a median (interquartile range) of 1 (1, 2). 2.6% (120) reported exchanging sex for benefits; 0.1% (3) were sex workers, 2.3% (106) had used illegal drugs, 31.1% (1421) planned their pregnancy and 31.8% (1455) experienced abuse. In logistic regression analyses, HIV status was predicted by one variable describing women's behaviour (lifetime sexual partners) and three variables describing partner risks (partner HIV+, migrant worker or suspected unfaithful). Women in our sample exhibited few behavioural risks for HIV but significant vulnerability via partner behaviours. To stem feminization of the epidemic, health authorities should complement existing prevention interventions in high-risk populations with directed efforts towards bridging populations such as migrant workers. We identify four locally adapted HIV prevention strategies.


Subject(s)
HIV Infections/epidemiology , Pregnancy Complications, Infectious/epidemiology , Adolescent , Cross-Sectional Studies , Female , Guatemala/epidemiology , Humans , Pregnancy , Risk Factors , Sexual Behavior , Sexual Partners , Surveys and Questionnaires , Virology/methods
6.
J Med Ethics ; 35(1): 57-64, 2009 Jan.
Article in English | MEDLINE | ID: mdl-19103946

ABSTRACT

OBJECTIVE: To determine whether a moral reasoning exercise can improve response quality to surveys of healthcare priorities METHODS: A randomised internet survey focussing on patient age in healthcare allocation was repeated twice. From 2574 internet panel members from the USA and Canada, 2020 (79%) completed the baseline survey and 1247 (62%) completed the follow-up. We elicited respondent preferences for age via five allocation scenarios. In each scenario, a hypothetical health planner made a decision to fund one of two programmes identical except for average patient age (35 vs 65 years). Half of the respondents (intervention group) were randomly assigned to receive an additional moral reasoning exercise. Responses were elicited again 7 weeks later. Numerical scores ranging from -5 (strongest preference for younger patients) to +5 (strongest preference for older patients); 0 indicates no age preference. Response quality was assessed by propensity to choose extreme or neutral values, internal consistency, temporal stability and appeal to prejudicial factors. RESULTS: With the exception of a scenario offering palliative care, respondents preferred offering scarce resources to younger patients in all clinical contexts. This preference for younger patients was weaker in the intervention group. Indicators of response quality favoured the intervention group. CONCLUSIONS: Although people generally prefer allocating scarce resources to young patients over older ones, these preferences are significantly reduced when participants are encouraged to reflect carefully on a wide range of moral principles. A moral reasoning exercise is a promising strategy to improve response quality to surveys of healthcare priorities.


Subject(s)
Decision Making/ethics , Health Care Rationing/ethics , Health Priorities/ethics , Adult , Age Factors , Aged , Canada , Female , Health Care Surveys , Humans , Internet , Male , Public Opinion , Surveys and Questionnaires , United States
7.
J Thromb Haemost ; 6(7): 1105-12, 2008 Jul.
Article in English | MEDLINE | ID: mdl-18466316

ABSTRACT

BACKGROUND/OBJECTIVES: We prospectively measured change in quality of life (QOL) during the 2 years after a diagnosis of deep vein thrombosis (DVT) and evaluated determinants of QOL, including development of the post-thrombotic syndrome (PTS). PATIENTS/METHODS: Consecutive patients with acute DVT were recruited from 2001 to 2004 at eight hospitals in Canada. At study visits at baseline, and 1, 4, 8, 12 and 24 months, clinical data were collected, standardized PTS assessments were performed, and QOL questionnaires were self-completed. Generic QOL was measured using the Short-Form Health Survey-36 (SF-36) questionnaire. Venous disease-specific QOL was measured using the Venous Insufficiency Epidemiological and Economic Study (VEINES)-QOL/Sym questionnaire. The change in QOL scores over a 2-year follow-up was assessed. The influence of PTS and other characteristics on QOL at 2 years was evaluated using multivariable regression analyses. RESULTS: Among the 387 patients recruited, the average age was 56 years, two-thirds were outpatients, and 60% had proximal DVT. The cumulative incidence of PTS was 47%. On average, QOL scores improved during follow-up. However, patients who developed PTS had lower scores at all visits and significantly less improvement in QOL over time (P-values for PTS*time interaction were 0.001, 0.012, 0.014 and 0.006 for PCS, MCS, VEINES-QOL and VEINES-Sym). Multivariable regression analyses showed that PTS (P < 0.0001), age (P = 0.0009), proximal DVT (P = 0.01) and inpatient status (P = 0.04) independently predicted 2-year SF-36 PCS scores. PTS alone independently predicted 2-year VEINES-QOL (P < 0.0001) and VEINES-Sym (P < 0.0001) scores. CONCLUSIONS: Development of PTS is the principal determinant of health-related QOL 2 years after DVT. Our study provides prognostic information on patient-reported outcomes after DVT and emphasizes the need for effective prevention and treatment of the PTS.


Subject(s)
Quality of Life , Venous Thrombosis/complications , Venous Thrombosis/psychology , Adult , Aged , Aged, 80 and over , Female , Follow-Up Studies , Humans , Male , Middle Aged , Postthrombotic Syndrome/diagnosis , Postthrombotic Syndrome/etiology , Prognosis , Prospective Studies , Surveys and Questionnaires , Venous Thrombosis/drug therapy
8.
Physiol Mol Biol Plants ; 14(1-2): 23-38, 2008 Apr.
Article in English | MEDLINE | ID: mdl-23572871

ABSTRACT

The patterns of phytohormones distribution, their native function and possible origin of hormonal regulation across the green plant lineages (chlorophytes, charophytes, bryophytes and tracheophytes) are discussed. The five classical phytohormones - auxins, cytokinins, gibberellins (GA), abscisic acid (ABA) and ethylene occur ubiquitously in green plants. They are produced as secondary metabolites by microorganisms. Some of the bacterial species use phytohormones to interact with the plant as a part of their colonization strategy. Phytohormone biosynthetic pathways in plants seem to be of microbial origin and furthermore, the origin of high affinity perception mechanism could have preceded the recruitment of a metabolite as a hormone. The bryophytes represent the earliest land plants which respond to the phytohormones with the exception of gibberellins. The regulation by auxin and ABA may have evolved before the separation of green algal lineage. Auxin enhances rhizoid and caulonemal differentiation while cytokinins enhance shoot bud formation in mosses. Ethylene retards cell division but seems to promote cell elongation. The presence of responses specific to cytokinins and ethylene strongly suggest the origin of their regulation in bryophytes. The hormonal role of GAs could have evolved in some of the ferns where antheridiogens (compounds related to GAs) and GAs themselves regulate the formation of antheridia. During migration of life forms to land, the tolerance to desiccation may have evolved and is now observed in some of the microorganisms, animals and plants. Besides plants, sequences coding for late embryogenesis abundant-like proteins occur in the genomes of other anhydrobiotic species of microorganisms and nematodes. ABA acts as a stress signal and increases rapidly upon desiccation or in response to some of the abiotic stresses in green plants. As the salt stress also increases ABA release in the culture medium of cyanobacterium Trichormus variabilis, the recruitment of ABA in the regulation of stress responses could have been derived from prokaryotes and present at the level of common ancestor of green plants. The overall hormonal action mechanisms in mosses are remarkably similar to that of the higher plants. As plants are thought to be monophyletic in origin, the existence of remarkably similar hormonal mechanisms in the mosses and higher plants, suggests that some of the basic elements of regulation cascade could have also evolved at the level of common ancestor of plants. The networking of various steps in a cascade or the crosstalk between different cascades is variable and reflects the dynamic interaction between a species and its specific environment.

9.
Soc Sci Med ; 58(10): 2069-81, 2004 May.
Article in English | MEDLINE | ID: mdl-15020020

ABSTRACT

The objective was to evaluate the associations between older persons' health status and their social integration and social networks (family, children, friends and community), in two French-speaking, Canadian community dwelling populations aged 65 years and over, using the conceptual framework proposed by Berkman and Thomas. Data were taken from two 1995 surveys conducted in the city of Moncton (n = 1518) and the Montreal neighbourhood of Hochelaga-Maisonneuve (n = 1500). Social engagement (a cumulative index of social activities), networks consisting of friends, family and children and social support were measured using validated scales. Multiple logistic regressions based on structured inclusion of potentially mediating variables were fitted to estimate the associations between health status and social networks. Self-rated health was better for those with a high level of social integration and a strong network of friends in both locations. In addition, in Hochelaga-Maisonneuve family and children networks were positively associated with good health, though the effect of friend networks was attenuated in the presence of disability, good social support from children was associated with good health. Age, sex and education were included as antecedent variables; smoking, alcohol consumption, exercise, locus of control and depressive symptoms were considered intermediary variables between social networks and health. In conclusion, social networks, integration and support demonstrated unique positive associations with health. The nature of these associations may vary between populations and cultures.


Subject(s)
Health Status , Interpersonal Relations , Residence Characteristics , Social Support , Activities of Daily Living , Aged , Aged, 80 and over , Attitude to Health , Disabled Persons/psychology , Family Relations , Female , Humans , Internal-External Control , Logistic Models , Male , New Brunswick , Quebec , Self Concept , Smoking , Sociology, Medical
10.
J Biosci ; 25(4): 331-8, 2000 Dec.
Article in English | MEDLINE | ID: mdl-11120585

ABSTRACT

Among the downstream targets of calcium in plants, calcium-dependent protein kinases (CDPKs) form an interesting class of kinases which are activated by calcium binding. They have been implicated in a diverse array of responses to hormonal and environmental stimuli. In order to dissect the role of CDPKs in the moss Funaria hygrometrica, a polymerase chain reaction (PCR)-based approach was adopted to clone the gene. Using degenerate PCR primers against conserved regions of CDPKs, a 900 bp amplicon was obtained from the genomic DNA of Funaria. Southern hybridization under low stringency conditions indicated the presence of several CDPK related sequences in the Funaria genome. This observation is consistent with reports of multigene families of CDPKs in other plants. The 900 bp fragment was subsequently used to isolate a 2.2 kb partial genomic clone of the CDPK gene from Funaria. The genomic clone encodes an open reading frame (ORF) of 518 amino acids. Interestingly, unlike other CDPK genes from plants, the entire 1.5 kb ORF is not interrupted by introns. The deduced amino acid sequence of the Funaria gene shows extensive homology with CDPKs from higher plants, 73% identity with the Fragaria CDPK and 71% identity with CDPK isoform 7 of Arabidopsis. Phylogenetic analysis revealed that the Funaria CDPK is closer to the CDPKs from higher plants like strawberry and Arabidopsis as compared to those from lower plants such as the liverwort Marchantia, the green alga Chlamydomonas or another moss Tortula. Northern analysis shows enhanced expression of the CDPK transcript within 24-48 h of starvation for nitrogen, phosphorus or sulphur. So far the only other kinase which is known to be induced by nutrient starvation in plants is the wpk 4 which is a snf-1 related kinase (SnRKs). To our knowledge this is the first report that implicates a CDPK in the starvation response.


Subject(s)
Bryopsida/enzymology , Bryopsida/physiology , Plant Proteins , Protein Kinases/biosynthesis , Protein Kinases/genetics , Up-Regulation , Amino Acid Sequence , Amino Acids/chemistry , Animals , Arabidopsis/enzymology , Blotting, Northern , Blotting, Southern , Bryopsida/growth & development , Cell Division , Chlamydomonas/enzymology , Cloning, Molecular , DNA, Complementary/metabolism , Gene Library , Introns , Molecular Sequence Data , Multigene Family , Nutritional Requirements , Open Reading Frames , Phosphorylation , Phylogeny , Polymerase Chain Reaction , Protein Isoforms , Protein Kinases/chemistry , Protein Kinases/metabolism , Protein Serine-Threonine Kinases/metabolism , Sequence Analysis, DNA , Sequence Homology, Amino Acid , Time Factors
11.
Health Care Manag Sci ; 3(3): 171-83, 2000 Jun.
Article in English | MEDLINE | ID: mdl-10907320

ABSTRACT

The goal of "treatment on demand" is to allow all those seeking substance abuse treatment immediate entry into a program. Surprisingly, little is understood regarding the relationship between the demand for treatment, queues, waiting times and treatment admission rates, and treatment capacity. Nor has the increase in treatment capacity required to eliminate drug treatment queues, along with the expected benefits and costs of such an expansion, been studied carefully. In this paper, we present a mathematical model of drug treatment flows for systems where the demand for treatment greatly exceeds available supply. The model produces estimates of queue lengths, waiting times and treatment admission probabilities for any given treatment capacity, and suggests the capacity needed to achieve treatment on demand. The model also enables one to contrast the likely costs and benefits of changes in treatment capacity. We illustrate the model using San Francisco as a case study.


Subject(s)
Health Services Needs and Demand/statistics & numerical data , Models, Theoretical , Substance Abuse Treatment Centers/statistics & numerical data , Substance-Related Disorders/epidemiology , Waiting Lists , Ambulatory Care , Efficiency, Organizational , Health Services Accessibility , Humans , Organizational Case Studies , San Francisco/epidemiology , Substance-Related Disorders/economics , Substance-Related Disorders/therapy
12.
AIDS Public Policy J ; 14(4): 136-46, 1999.
Article in English | MEDLINE | ID: mdl-11148944

ABSTRACT

A system of HIV surveillance based on AIDS case reporting is no longer adequate to monitor the epidemic of HIV/AIDS in the U.S. We are now faced with the challenge of designing an effective system of HIV surveillance. The "New Approaches to HIV Surveillance: Means and Ends" conference emphasized that there are several alternatives, each with strengths and limitations. The CDC has recommended that all states adopt a system of HIV surveillance based on case reporting. Although it has not specified that such systems need be name-based, CDC appears to reward states that adopt name-reporting systems. The rationale for this stance should be reviewed and made explicit. Name reporting may be superior in some respects to a system of case reports based on unique identifiers (UIs), especially in its greater ability to link surveillance activities to follow up at the individual level. Neither a name-reporting nor a UI approach to case reporting would provide HIV incidence data. The only currently envisioned means of providing incidence data is statistical estimation based on "snapshot estimates" of HIV incidence in sample cohorts. Calibration of this new instrument for HIV incidence estimation against existing data or through field trials is of critical importance.


Subject(s)
HIV Infections/epidemiology , Population Surveillance/methods , Centers for Disease Control and Prevention, U.S. , Confidentiality , Contact Tracing/methods , Contact Tracing/trends , Data Collection/methods , Data Collection/standards , Data Collection/trends , Data Interpretation, Statistical , Disease Notification/methods , Disease Notification/standards , Forecasting , HIV Infections/etiology , HIV Infections/prevention & control , Humans , Incidence , Mandatory Testing/methods , Mandatory Testing/standards , Mandatory Testing/trends , Mass Screening/methods , Mass Screening/standards , Mass Screening/trends , Medical Record Linkage/methods , Medical Record Linkage/standards , Organizational Objectives , Prevalence , Reproducibility of Results , United States/epidemiology
13.
Indian Heart J ; 44(6): 399-402, 1992.
Article in English | MEDLINE | ID: mdl-1307090

ABSTRACT

Two dimensional and pulsed Doppler echocardiographic studies were performed in human fetuses with the aim to establish normal values for blood flow velocities and cardiac output in Indian subjects. Thirteen pregnant mothers were prospectively followed up at 4 weeks interval from 19 to 40 weeks of gestation. Blood flow velocity spectra across aortic, pulmonary, mitral and tricuspid valves were analyzed to obtain peak flow velocity (cm/sec) and velocity time integral. Aortic and pulmonary diameters were measured at the valve level from two dimensional echocardiographic images and ventricular stroke volume calculated. The values were plotted against fetal age (weeks) and fetal weight (gms). Our results showed that there is a linear increase of the measured Doppler data, with increasing gestational age and weight. These values may be used as a reference for the Indian population.


Subject(s)
Cardiac Output , Coronary Circulation , Echocardiography, Doppler , Fetus/physiology , Ultrasonography, Prenatal , Blood Flow Velocity , Coronary Circulation/physiology , Female , Humans , Pregnancy , Prospective Studies
14.
J Assoc Physicians India ; 39(7): 575-6, 1991 Jul.
Article in English | MEDLINE | ID: mdl-1800510

ABSTRACT

We report a 50 year old man with lumbar canal stenosis proved on myelography, who presented with hesitancy, constipation and numbness in the "saddle area", with mild and transient lumbago and no claudication. His symptoms improved over several months after surgery.


Subject(s)
Constipation/etiology , Spinal Stenosis/complications , Urination Disorders/etiology , Humans , Lumbar Vertebrae , Male , Middle Aged , Nerve Compression Syndromes/etiology , Spinal Nerve Roots
15.
Indian J Med Res ; 92: 417-9, 1990 Dec.
Article in English | MEDLINE | ID: mdl-2079356

ABSTRACT

3,4-Dihydroxyphenyl ethylene glycol (DOPEG), a metabolite of noradrenaline (NA), was estimated in CSF of 30 patients of depression diagnosed by the criteria of American Psychiatric Association in DSM-III; and compared with levels in 10 non-depressed individuals who served as controls. Mean DOPEG levels in CSF in the patient group (801.37 +/- 28.09 micrograms/l) were significantly higher (P less than 0.01) than those in the control group (724.3 +/- 34.62 micrograms/l). Formation of excessive amount of this particular metabolite suggests an excessive intraneuronal deamination of NA, partially accounting for the overall decline in the availability of NA in the noradrenergic neurons in patients of depression.


Subject(s)
Depression/metabolism , Methoxyhydroxyphenylglycol/analogs & derivatives , Depression/cerebrospinal fluid , Female , Humans , India , Male , Methoxyhydroxyphenylglycol/cerebrospinal fluid , Norepinephrine/metabolism
16.
Biosci Rep ; 8(6): 553-64, 1988 Dec.
Article in English | MEDLINE | ID: mdl-3242643

ABSTRACT

An overview of plant development has been presented. In lower plants like mosses, auxin and cytokinin regulate the creation and the stability of the differentiated state of various cell types. The differentiated state is plastic and all cell types dedifferentiate to ground state, the chloronema. Even in higher plants, embryonic cells become only roughly committed during shoot meristem formation. Their terminal destiny becomes specified during the post-germination phase when the rough outline gets refined. The lack of a firm determined state, clonally heritable through mitosis, indicates that the development in plants is unlikely to be specified by a rigid programme.


Subject(s)
Plant Development , Cell Differentiation , Cytokinins/physiology , Indoleacetic Acids/physiology , Plant Cells , Plant Physiological Phenomena
17.
Dev Biol ; 97(1): 154-72, 1983 May.
Article in English | MEDLINE | ID: mdl-6840396

ABSTRACT

The development of the tassel and the ear shoot has been investigated in corn (Zea mays L.). X irradiation of dry kernels and seedlings heterozygous for anthocyanin markers or for factors altering tassel and ear morphology results in the formation of clones (sectors) from cells of the apical meristem. Most tassels develop from 4 +/- 1 cells of the mature embryo. The expression of ramosa-1, tunicate, tassel seed-6, and vestigial is cell autonomous in the tassel. These genes act late in development and modify the developmental fate or decision of an individual clone and not of the whole group of cells producing a tassel. The ear shoot develops from lineages of one to three cells derived each from the L-I (outmost cell layer) and L-II (second cell layer) of the apical meristem. Typically the clones start in the ear shoot (in the husks and possibly in the cob), extend upward in an internode, continue along the margin of the leaf sheath or leaf blade at the node above, and terminate in this or the next higher leaf. The separation of lineages for ear shoot and internode occurs in the period around 13 days after sowing. The analysis of clonal boundaries shows that a small number of embryonic cells become isolated in their developmental capacity. This commitment process appears to be analogous to the process of compartmentation in the imaginal disks of fruit flies. The extent of proliferation of individual cells within a group of highly flexible and any particular clone does not generate a specific part of a tassel or an ear shoot. There must be cellular communication between various clones so that the overall size and morphology of an organ remain normal and more or less fixed. Thus the process of development in plants is also highly regulative in nature and shares many features in common with development in fruit flies.


Subject(s)
Plant Development , Anthocyanins/genetics , Cell Division , Clone Cells/cytology , Morphogenesis , Seeds/radiation effects , Zea mays/cytology , Zea mays/genetics , Zea mays/growth & development
19.
Plant Physiol ; 69(6): 1401-3, 1982 Jun.
Article in English | MEDLINE | ID: mdl-16662411

ABSTRACT

Suspension cultures of intact chloronema cells of the moss Funaria hygrometrica take up [(3)H]cAMP and degrade it rapidly. The increase in total radioactivity accumulated by the cells was linear up to 30 minutes. Initially, the major degradation products were 5'-AMP and adenosine, but later predominantly ADP and ATP. In spite of rapid degradation, the amount of extracellularly applied cAMP retained by the cells is about 4-fold higher than the maximum endogenous level of cAMP reported previously (Handa, Johri 1977 Plant Physiol 59: 490-496). The uptake showed a distinct dependence on the density of the culture. Cells at a lower cell density (1-2 milligrams per milliliter) accumulated 4 to 6 times more radioactivity than the cells at high density (>10 milligrams per milliliter). The cyclic nucleotide phosphodiesterase (cNPDE) activity of whole cells (18 milliunits per milligram protein) was comparable to that of protoplasts (23 milliunits per milligram protein), but about 4-fold lower than that of lysed protoplasts (80 milliunits per milligram protein), indicating an intracellular degradation of cAMP by chloronema cells.

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