Spatial distribution analysis of Dicksonia sellowiana Hook. in Araucaria forest fragments with different sizes / Análise da distribuição espacial de Dicksonia sellowiana Hook. em fragmentos de Floresta com Araucária com diferentes tamanhos

Abstract Dicksonia sellowiana Hook. (Dicksoniaceae) is target of extractive exploitation and is threatened with extinction. We analyzed the population structure, the spatial distribution pattern of D. sellowiana and its relationship with environmental parameters within three fragments of Araucaria Forest in Rio Grande do Sul, Brazil. The fragments are of different sizes, namely, large (H1LF) with 246 ha, medium (H2MF) with 57 ha and small (H3SF) with 5.2 ha. Within each site, 1 ha was delimited, divided into 100 subplots (100 m2), of which 20 were selected with a draw. In each subplot, counting of the individuals, the registration of the caudice height and the coverage of leaves (SC) (m2), measurements of photosynthetically active radiation (PAR), canopy opening degree (CO), soil moisture (SM) and litter thickness (LT). The temperature (T) was measured inside each site. A total of 792 plants were sampled, of which 551 were concentrated in H1LF, 108 in H2MF and 133 in H3SF. An average of 1320 ha-1 individuals were estimated. Of the total including the three fragments, 96.9% of the individuals are in the first class of height (up to 0.8 m), indicating a great potential of population development. The spatial distribution pattern (AI) was aggregated in the three populations and the plants presented a heterogeneous total coverage, between 4.73 m2 (H2MF) and 2,223.47 m2 (H1LF). The highest values ​​of SC and SM were more related to the distribution of individuals in H1LF whereas the opposite was recorded in H2MF. The highest values ​​of PAR, LT and CO correlated with the distribution of D. sellowiana in H3SF. In addition to revealing that the H1LF population is among the most dense in southern Brazil, the results demonstrated a significant structural distinction between the interior populations of the fragments, in spite of them being located near to one another and being part of the same natural field matrix.

Resumo Dicksonia sellowiana Hook. (Dicksoniaceae) é alvo de exploração extrativista e encontra-se ameaçada de extinção. Analisamos a estrutura populacional, o padrão de distribuição espacial de D. sellowiana e sua relação com parâmetros ambientais no interior de três fragmentos de Floresta com Araucária, no Rio Grande do Sul (RS), Brasil. Os fragmentos possuem diferentes tamanhos sendo denominados de grande (H1LF) com 246 ha, médio (H2MF) com 57 ha e de pequeno (H3SF) com 5,2 ha. No interior de cada sítio, foi demarcado 1 ha, fracionado em 100 subparcelas (100m2), das quais 20 foram sorteadas. Em cada subparcela foi feita a contagem dos indivíduos, o registro da altura do cáudice e da cobertura (SC) (m2) das folhas, as medições da radiação fotossinteticamente ativa (PAR), grau de abertura do dossel (CO), umidade do solo (SM) e espessura da serapilheira (LT). A temperatura (T) foi medida no interior de cada sítio. Foram amostradas 792 plantas, das quais 551 concentradas no H1LF, 108 no H2MF e 133 no H3SF e em média foram estimados 1320 indivíduos ha-1. Do total dos três fragmentos, 96,9% dos indivíduos estão na primeira classe de altura (até 0,8 m), indicando grande potencial de desenvolvimento das populações. O padrão de distribuição espacial (AI) foi agregado nas três populações e as plantas apresentaram uma cobertura total heterogênea, entre 4,73m2 (H2MF) e 2.223,47m 2 (H1LF). Os maiores valores de SC e de SM foram mais relacionadas com a distribuição dos indivíduos no H1LF enquanto que o contrário foi registrado no H2MF. Os maiores valores de PAR, LT e de CO relacionaram-se com a distribuição de D. sellowiana no H3SF. Além de revelar que a população do H1LF está entre as mais densas já descritas no sul do Brasil, os resultados demonstraram uma significativa distinção estrutural entre as populações dos interiores dos fragmentos com diferentes tamanhos, embora muito próximos geograficamente e inseridos em uma mesma matriz de campo natural.

Spatial distribution analysis of Dicksonia sellowiana Hook. in Araucaria forest fragments with different sizes.

Dicksonia sellowiana Hook. (Dicksoniaceae) is target of extractive exploitation and is threatened with extinction. We analyzed the population structure, the spatial distribution pattern of D. sellowiana and its relationship with environmental parameters within three fragments of Araucaria Forest in Rio Grande do Sul, Brazil. The fragments are of different sizes, namely, large (H1LF) with 246 ha, medium (H2MF) with 57 ha and small (H3SF) with 5.2 ha. Within each site, 1 ha was delimited, divided into 100 subplots (100 m2), of which 20 were selected with a draw. In each subplot, counting of the individuals, the registration of the caudice height and the coverage of leaves (SC) (m2), measurements of photosynthetically active radiation (PAR), canopy opening degree (CO), soil moisture (SM) and litter thickness (LT). The temperature (T) was measured inside each site. A total of 792 plants were sampled, of which 551 were concentrated in H1LF, 108 in H2MF and 133 in H3SF. An average of 1320 ha-1 individuals were estimated. Of the total including the three fragments, 96.9% of the individuals are in the first class of height (up to 0.8 m), indicating a great potential of population development. The spatial distribution pattern (AI) was aggregated in the three populations and the plants presented a heterogeneous total coverage, between 4.73 m2 (H2MF) and 2,223.47 m2 (H1LF). The highest values ​​of SC and SM were more related to the distribution of individuals in H1LF whereas the opposite was recorded in H2MF. The highest values ​​of PAR, LT and CO correlated with the distribution of D. sellowiana in H3SF. In addition to revealing that the H1LF population is among the most dense in southern Brazil, the results demonstrated a significant structural distinction between the interior populations of the fragments, in spite of them being located near to one another and being part of the same natural field matrix.

Spatial distribution analysis of Dicksonia sellowiana Hook. in Araucaria forest fragments with different sizes

Abstract Dicksonia sellowiana Hook. (Dicksoniaceae) is target of extractive exploitation and is threatened with extinction. We analyzed the population structure, the spatial distribution pattern of D. sellowiana and its relationship with environmental parameters within three fragments of Araucaria Forest in Rio Grande do Sul, Brazil. The fragments are of different sizes, namely, large (H1LF) with 246 ha, medium (H2MF) with 57 ha and small (H3SF) with 5.2 ha. Within each site, 1 ha was delimited, divided into 100 subplots (100 m2), of which 20 were selected with a draw. In each subplot, counting of the individuals, the registration of the caudice height and the coverage of leaves (SC) (m2), measurements of photosynthetically active radiation (PAR), canopy opening degree (CO), soil moisture (SM) and litter thickness (LT). The temperature (T) was measured inside each site. A total of 792 plants were sampled, of which 551 were concentrated in H1LF, 108 in H2MF and 133 in H3SF. An average of 1320 ha-1 individuals were estimated. Of the total including the three fragments, 96.9% of the individuals are in the first class of height (up to 0.8 m), indicating a great potential of population development. The spatial distribution pattern (AI) was aggregated in the three populations and the plants presented a heterogeneous total coverage, between 4.73 m2 (H2MF) and 2,223.47 m2 (H1LF). The highest values of SC and SM were more related to the distribution of individuals in H1LF whereas the opposite was recorded in H2MF. The highest values of PAR, LT and CO correlated with the distribution of D. sellowiana in H3SF. In addition to revealing that the H1LF population is among the most dense in southern Brazil, the results demonstrated a significant structural distinction between the interior populations of the fragments, in spite of them being located near to one another and being part of the same natural field matrix.

Resumo Dicksonia sellowiana Hook. (Dicksoniaceae) é alvo de exploração extrativista e encontra-se ameaçada de extinção. Analisamos a estrutura populacional, o padrão de distribuição espacial de D. sellowiana e sua relação com parâmetros ambientais no interior de três fragmentos de Floresta com Araucária, no Rio Grande do Sul (RS), Brasil. Os fragmentos possuem diferentes tamanhos sendo denominados de grande (H1LF) com 246 ha, médio (H2MF) com 57 ha e de pequeno (H3SF) com 5,2 ha. No interior de cada sítio, foi demarcado 1 ha, fracionado em 100 subparcelas (100m2), das quais 20 foram sorteadas. Em cada subparcela foi feita a contagem dos indivíduos, o registro da altura do cáudice e da cobertura (SC) (m2) das folhas, as medições da radiação fotossinteticamente ativa (PAR), grau de abertura do dossel (CO), umidade do solo (SM) e espessura da serapilheira (LT). A temperatura (T) foi medida no interior de cada sítio. Foram amostradas 792 plantas, das quais 551 concentradas no H1LF, 108 no H2MF e 133 no H3SF e em média foram estimados 1320 indivíduos ha-1. Do total dos três fragmentos, 96,9% dos indivíduos estão na primeira classe de altura (até 0,8 m), indicando grande potencial de desenvolvimento das populações. O padrão de distribuição espacial (AI) foi agregado nas três populações e as plantas apresentaram uma cobertura total heterogênea, entre 4,73m2 (H2MF) e 2.223,47m 2 (H1LF). Os maiores valores de SC e de SM foram mais relacionadas com a distribuição dos indivíduos no H1LF enquanto que o contrário foi registrado no H2MF. Os maiores valores de PAR, LT e de CO relacionaram-se com a distribuição de D. sellowiana no H3SF. Além de revelar que a população do H1LF está entre as mais densas já descritas no sul do Brasil, os resultados demonstraram uma significativa distinção estrutural entre as populações dos interiores dos fragmentos com diferentes tamanhos, embora muito próximos geograficamente e inseridos em uma mesma matriz de campo natural.

GABA estimation in the brains of children on the autism spectrum: measurement precision and regional cortical variation.

(1)H magnetic resonance spectroscopy ((1)H MRS) and spectral editing methods, such as MEGA-PRESS, allow researchers to investigate metabolite and neurotransmitter concentrations in-vivo. Here we address the utilization of (1)H MRS for the investigation of GABA concentrations in the ASD brain, in three locations; motor, visual and auditory areas. An initial repeatability study (5 subjects, 5 repeated measures separated by ~5days on average) indicated no significant effect of reference metabolite choice on GABA quantitation (p>0.6). Coefficients of variation for GABA+/NAA, GABA+/Cr and GABA+/Glx were all of the order of 9-11%. Based on these findings, we investigated creatine-normalized GABA+ ratios (GABA+/Cr) in a group of (N=17) children with autism spectrum disorder (ASD) and (N=17) typically developing children (TD) for Motor, Auditory and Visual regions of interest (ROIs). Linear regression analysis of gray matter (GM) volume changes (known to occur with development) revealed a significant decrease of GM volume with Age for Motor (F(1,30)=17.92; p<0.001) and Visual F(1,16)=14.41; p<0.005 but not the Auditory ROI (p=0.55). Inspection of GABA+/Cr changes with Age revealed a marginally significant change for the Motor ROI only (F(1,30)=4.11; p=0.054). Subsequent analyses were thus conducted for each ROI separately using Age and GM volume as covariates. No group differences in GABA+/Cr were observed for the Visual ROI between TD vs. ASD children. However, the Motor and Auditory ROI showed significantly reduced GABA+/Cr in ASD (Motor p<0.05; Auditory p<0.01). The mean deficiency in GABA+/Cr from the Motor ROI was approximately 11% and Auditory ROI was approximately 22%. Our novel findings support the model of regional differences in GABA+/Cr in the ASD brain, primarily in Auditory and to a lesser extent Motor but not Visual areas.

Quantification of antiangiogenic and antivascular drug activity by kinetic analysis of DCE-MRI data.

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can be used to quantify the response of tumors to vascular targeting agents. Tumor response is frequently assessed using mathematical models that describe the distribution of contrast agents over time as a function of fundamental characteristics of vascular physiology. Generally, mathematical models of biological systems are abstractions that attempt to retain fundamental physiologic characteristics, thereby allowing for multiple potential modeling approaches and structures. Various DCE-MRI modeling techniques are discussed in this article.

Nucleus accumbens and effort-related functions: behavioral and neural markers of the interactions between adenosine A2A and dopamine D2 receptors.

Nucleus accumbens dopamine (DA) is a critical component of the brain circuitry regulating work output in reinforcement-seeking behavior and effort-related choice behavior. Moreover, there is evidence of an interaction between DA D(2) and adenosine A(2A) receptor function. Systemic administration of adenosine A(2A) antagonists reverses the effects of D(2) antagonists on tasks that assess effort related choice. The present experiments were conducted to determine if nucleus accumbens is a brain locus at which adenosine A(2A) and DA D(2) antagonists interact to regulate effort-related choice behavior. A concurrent fixed ratio 5 (FR5)/chow feeding procedure was used; with this procedure, rats can choose between completing an FR5 lever-pressing requirement for a preferred food (i.e., high carbohydrate operant pellets) or approaching and consuming a freely available food (i.e., standard rodent chow). Rats trained with this procedure spend most of their time pressing the lever for the preferred food, and eat very little of the concurrently available chow. Intracranial injections of the selective DA D(2) receptor antagonist eticlopride (1.0, 2.0, 4.0 microg) into nucleus accumbens core, but not a dorsal control site, suppressed FR5 lever-pressing and increased consumption of freely available chow. Either systemic or intra-accumbens injections of the adenosine A(2A) receptor antagonist MSX-3 reversed these effects of eticlopride on effort-related choice. Intra-accumbens injections of eticlopride also increased local expression of c-Fos immunoreactivity, and this effect was attenuated by co-administration of MSX-3. Adenosine and DA systems interact to regulate instrumental behavior and effort-related processes, and nucleus accumbens is an important locus for this interaction. These findings may have implications for the treatment of psychiatric symptoms such as psychomotor slowing, anergia and fatigue.

Cultural enhancement of a clinical service to meet the needs of indigenous people; genetic service development in response to issues for New Zealand Maori.

The delivery of good health care services within clinical settings is predicated by an understanding of the needs of the stakeholders. Most of the information generated to date on the transfer of mutational analysis to clinical service has been within a Eurocentric model favouring individual autonomy. It is predictable that this model does not easily translate for other cultures. Current genetic technology has elucidated the molecular basis of many diseases. In familial cancer and other late-onset disorders, there is now the possibility of 'prediction' where a high risk conferred by family history can be confirmed or negated by genetic testing. In paediatric disorders, prediction is offered in the form of prenatal or pre-implantation genetic diagnosis. We report on the processes undertaken in an attempt to provide a culturally sensitive service for the Maori people of Aotearoa, New Zealand.

Investigations in vivo of the effects of carbogen breathing on 5-fluorouracil pharmacokinetics and physiology of solid rodent tumours.

PURPOSE: We have shown previously that carbogen (95% 0(2), 5% CO(2)) breathing by rodents can increase uptake of anticancer drugs into tumours. The aim of this study was to extend these observations to other rodent models using the anticancer drug 5-fluorouracil (5FU). 5FU pharmacokinetics in tumour and plasma and physiological effects on the tumour by carbogen were investigated to determine the locus of carbogen action on augmenting tumour uptake of 5FU. METHODS: Two different tumour models were used, rat GH3 prolactinomas xenografted s.c. into nude mice and rat H9618a hepatomas grown s.c. in syngeneic Buffalo rats. Uptake and metabolism of 5FU in both tumour models with or without host carbogen breathing was studied non-invasively using fluorine-19 magnetic resonance spectroscopy ((19)F-MRS), while plasma samples from Buffalo rats were used to construct a NONMEM pharmacokinetic model. Physiological effects of carbogen on tumours were studied using (31)P-MRS for energy status (NTP/Pi) and pH, and gradient-recalled echo magnetic resonance imaging (GRE-MRI) for blood flow and oxygenation. RESULTS: In both tumour models, carbogan-induced GRE-MRI signal intensity increases of approximately 60% consistent with an increase in tumour blood oxygenation and/or flow. In GH3 xenografts, (19)F-MRS showed that carbogen had no significant effect on 5FU uptake and metabolism by the tumours, and (31)P-MRS showed there was no change in the NTP/Pi ratio. In H9618a hepatomas, (19)F-MRS showed that carbogen had no effect on tumour 5FU uptake but significantly ( p=0.0003) increased 5FU elimination from the tumour (i.e. decreased the t(1/2)) and significantly ( p=0.029) increased (53%) the rate of metabolism to cytotoxic fluoronucleotides (FNuct). The pharmacokinetic analysis showed that carbogen increased the rate of tumour uptake of 5FU from the plasma but also increased the rate of removal. (31)P-MRS showed there were significant ( p

Contributions of hippocampal cellular damage and NMDA receptor dysfunction to behavioral markers of schizophrenia.

Pathological changes in the hippocampal formation have been noted in schizophrenic patients and manipulation of neurochemical functions within the limbic system has been shown to yield behavioral changes consistent with schizophrenia. The present study evaluated the impact of kainic acid induced hippocampal cellular damage and manipulation of NMDA receptor function (agonism and antagonism) on common behavioral markers of schizophrenia (habituation and prepulse inhibition of the acoustic startle response in rats). Cellular damage significantly impaired habituation and NMDA antagonism disrupted prepulse inhibition. Damage induced impairment of habituation is consistent with effects on latent inhibition (which is also unaffected by NMDA antagonism) while the antagonist disruption of prepulse inhibition is consistent with effects on associative plasticity. The current findings provide further support for a diverse neurobiological substrate of schizophrenic symptoms suggesting that pharmacologic intervention may need to be multifaceted and could involve competing mechanisms. Cognitive impairments may reflect diminished NMDA receptor function whereas positive symptoms may reflect heightened engagement of anatomically disturbed cellular elements.

Dynamic contrast-enhanced MRI using Gd-DTPA: interindividual variability of the arterial input function and consequences for the assessment of kinetics in tumors.

Gd-DTPA kinetics in arterial blood was investigated by dynamic MRI in 47 patients with malignant and benign mammary tumors. Signal enhancement was monitored for 10 min after the beginning of a 1-min infusion of 0.1 mmol/kg Gd-DTPA. Kinetics in blood was biexponential with median half-lives of 21 sec and 11.1 min, respectively. Peak signal enhancement and the area under the signal enhancement-time curve varied 2.5- and 3.7-fold between patients. The shortest mean residence time in one of up to three tumor compartments, MRT*, was estimated using either the individual (reference) or a mean population (surrogate) arterial input function (AIF). MRT* (reference estimate) was 1.0 (0-1.5), 1.9 (1.5-2.3), and 2.5 (2.3-2.8) min in carcinomas, fibroadenomas, and mastopathies, respectively (median and interquartile distance). Surrogate estimates were unbiased but differed from the reference estimates 1.5-fold or more in 23% of cases. AIFs should be monitored individually if accurate estimates of individual MRT* are desired.

Genetics of club foot in Maori and Pacific people.

The role of major gene and multifactorial inheritance in the aetiology of club foot in the New Zealand Polynesian population was studied using 287 New Zealand Maori and Pacific club foot families. The club foot family data were analysed by complex segregation analysis under the mixed model using the computer program POINTER. This analysis shows that the best genetic model for club foot in this population is a single dominant gene with a penetrance of 33% and a predicted gene frequency of 0.9%. These data provide a scientific foundation for molecular studies in the Maori and Polynesian population to identify putative club foot genes.

Unilateral hippocampal damage impairs spatial cognition in rats.

Unilateral temporal lobectomy to treat seizure disorders in humans often results in cognitive impairment after the surgery. To determine the potential utility of a rodent model of unilaterally induced cognitive deficits, the present experiment evaluated spatial cognition in adult rats after either left or right hemisphere lesioning of temporal neocortex and underlying hippocampal regions. Evaluation of performance in the eight arm radial maze revealed that both lesioned groups committed more reference memory errors than did nonoperated controls. Working memory errors did not differ statistically between groups. The production of a spatial learning deficit by unilateral damage suggests that this rodent model could serve to test potential improvements in interventional strategies aimed at attenuating cognitive effects of the surgical treatment.

Developmental stress disrupts habituation but spares prepulse inhibition in young rats.

Stress has long been recognized as a factor that contributes to the induction of schizophrenia and results in abnormal sensorimotor functioning and information processing. Patients with schizophrenia show disrupted habituation and prepulse inhibition of the acoustic startle response. This study examined the effects of maternal isolation in rats on the habituation of startle and PPI to assess the potential impact of developmental stress on schizophrenic symptomatology. Evaluation of performance in young adulthood (3-4 months) revealed a disruption of habituation in the isolated group; response amplitude increased over time. PPI was not altered. These results suggest that the disruption of habituation may involve acute effects of elevated stress hormones on neuronal functions. In contrast, disturbance of PPI may require an accrual of neuronal insult and damage to ultimately undermine neurologic function, possibly through impact on N-methyl-D-aspartate-mediated transmission. An analysis of effects at middle age is planned to address this possibility.

MR imaging of tumor microcirculation: promise for the new millennium.

Dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) is a method of imaging the physiology of the microcirculation. A series of recent clinical studies have shown that DCE MRI can measure and predict tumor response to therapy. Recent advances in MR technology provide the enhanced spatial and temporal resolution that allow the application of this methodology in the management of cancer patients. The September issue of this journal provided a microcirculation section to update readers on this exciting and challenging topic. Evidence is mounting that DCE MRI-based measures correlate well with tumor angiogenesis. DCE MRI has already been shown in several types of tumors to correlate well with traditional outcome measures, such as histopathologic studies, and with survival. These new measures are sensitive to tumor physiology and to the pharmacokinetics of the contrast agent in individual tumors. Moreover, they can present anatomical images of tumor microcirculation at excellent spatial resolution. Several issues have emerged from recent international workshops that must be addressed to move this methodology into routine clinical practice. First, is complex modeling of DCE MRI really necessary to answer clinical questions reliably? Clinical research has shown that, for tumors such as bone sarcomas, reliable outcome measures of tumor response to chemotherapy can be extracted from DCE MRI by methods ranging from simple measures of enhancement to pharmacokinetic models. However, the use of similar methods to answer a different question-the differentiation of malignant from benign breast tumors-has yielded contradictory results. Thus, no simple, one-size-fits-all-tumors solution has yet been identified. Second, what is the most rational and reliable data collection procedure for the DCE MRI evaluation? Several groups have addressed population variations in some key variables, such as tumor T(1)0 (T(1) prior to contrast administration) and the arterial input function C(a)(t) for contrast agent, and how they influence the precision and accuracy of DCE MRI outcomes. However, despite these potential complications, clinical studies in this section show that some tumor types can be assessed by relatively simple dynamic measures and analyses. The clinical scenario and tumor type may well determine the required complexity of the DCE MRI exam procedure and its analysis. Finally, we suggest that a consensus on naming conventions (nomenclature) is needed to facilitate comparison and analysis of the results of studies conducted at different centers. J. Magn. Reson. Imaging 10:903-907, 1999.