The distribution and morphological characteristics of catecholaminergic cells in the brain of monotremes as revealed by tyrosine hydroxylase immunohistochemistry

The present study describes the distribution and cellular morphology of catecholaminergic neurons in the CNS of two species of monotreme, the platypus (Ornithorhynchus anatinus) and the short-beaked echidna (Tachyglossus aculeatus). Tyrosine hydroxylase immunohistochemistry was used to visualize these neurons. The standard A1-A17, C1-C3 nomenclature was used for expediency, but the neuroanatomical names of the various nuclei have also been given. Monotremes exhibit catecholaminergic neurons in the diencephalon (All, A12, A13, A14, A15), midbrain (A8, A9, A10), rostral rhombencephalon (A5, A6, A7), and medulla (A1, A2, C1, C2). The subdivisions of these neurons are in general agreement with those of other mammals, and indeed other amniotes. Apart from minor differences, those being a lack of A4, A3, and C3 groups, the catecholaminergic system of monotremes is very similar to that of other mammals. Catecholaminergic neurons outside these nuclei, such as those reported for other mammals, were not numerous with occasional cells observed in the striatum. It seems unlikely that differences in the sleep phenomenology of monotremes, as compared to other mammals, can be explained by these differences. The similarity of this system across mammalian and amniote species underlines the evolutionary conservatism of the catecholaminergic system. Copyright (C) 2002 S. Karger AG, Basel.

The distribution and morphological characteristics of serotonergic cells in the brain of monotremes

The distribution and cellular morphology of serotonergic neurons in the brain of two species of monotremes are described. Three clusters of serotonergic neurons were found: a hypothalamic cluster, a cluster in the rostral brainstem and a cluster in the caudal brainstem. Those in the hypothalamus consisted of two groups, the periventricular hypothalamic organ and the infundibular recess, that were intimately associated with the ependymal wall of the third ventricle. Within the rostral brainstem cluster, three distinct divisions were found: the dorsal raphe nucleus (with four subdivisions), the median raphe nucleus and the cells of the supralemniscal region. The dorsal raphe was within and adjacent to the periaqueductal gray matter, the median raphe was associated with the midline ventral to the dorsal raphe, and the cells of the supralemniscal region were in the tegmentum lateral to the median raphe and ventral to the dorsal raphe. The caudal cluster consisted of three divisions: the raphe obscurus nucleus, the raphe pallidus nucleus and the raphe magnus nucleus. The raphe obscurus nucleus was associated with the dorsal midline at the caudal-most part of the medulla oblongata. The raphe pallidus nucleus was found at the ventral midline of the medulla around the inferior olive. Raphe magnus was associated with the midline of the medulla and was found rostral to both the raphe obscurus and raphe pallidus. The results of our study are compared in an evolutionary context with those reported for other mammals and reptiles. Copyright (C) 2002 S. Karger AG, Basel.

The distribution and morphological characteristics of cholinergic cells in the brain of monotremes as revealed by ChAT immunohistochemistry

The present study employs choline acetyltransferase (ChAT) immunohistochemistry to identify the cholinergic neuronal population in the central nervous system of the monotremes. Two of the three extant species of monotreme were studied: the platypus (Omithorhynchus anatinus) and the short-beaked echidna (Tachyglossus aculeatus). The distribution of cholinergic cells in the brain of these two species was virtually identical. Distinct groups of cholinergic cells were observed in the striatum, basal forebrain, habenula, pontomesencephalon, cranial nerve motor nuclei, and spinal cord. In contrast to other tetrapods studied with this technique, we failed to find evidence for cholinergic cells in the hypothalamus, the parabigeminal nucleus (or nucleus isthmus), or the cerebral cortex. The lack of hypothalamic cholinergic neurons creates a hiatus in the continuous antero-posterior aggregation of cholinergic neurons seen in other tetrapods. This hiatus might be functionally related to the phenomenology of monotreme sleep and to the ontogeny of sleep in mammals, as juvenile placental mammals exhibit a similar combination of sleep elements to that found in adult monotremes. Copyright (C) 2002 S. Karger AG, Basel.

Effects of habitat characteristics and climate on the distribution and colouration of Dusky Moorhens (Gallinula tenebrosa) in south-east Queensland

We determined which factors predict the presence and abundance of Dusky Moorhens (Gallinula tenebrosa) at wetlands by surveying the ecological and habitat characteristics of 62 sites across south-east Queensland. Moorhens were observed in 48 of the sites sampled. They were more likely to be found at sites surrounded by taller terrestrial vegetation and where free-floating and attached aquatic vegetation was more abundant. The number of moorhens found at a site increased in relation to vegetation height, the abundance of attached aquatic vegetation and the number of purple swamphens observed. These results suggest that there are ecological constraints on the distribution of moorhens, and that food abundance and the availability of suitable nesting sites determine the overall distribution and abundance of moorhens in wetlands. Adult moorhens develop brightly coloured fleshy frontal shields, bills and legs when breeding, although in some populations birds maintain year-round colouration. We observed year-round breeding colouration in 23 out of 34 sampling sites that had moorhens and were surveyed in August. Coloured moorhens were found during winter at sites with higher minimum winter temperatures, and more abundant free-floating and submerged leafy vegetation. In addition, higher proportions of moorhens were coloured at sites with higher mean minimum temperatures. The retention of year-round breeding colouration appears to be restricted to areas with warmer winter temperatures and more abundant food. The results suggest that areas not occupied by moorhens are of inadequate quality to support breeding populations. We suggest that ecological constraints on independent breeding in Dusky Moorhens may have favoured the evolution of their unusual cooperative breeding system, which involves frequent mate-sharing by both sexes.

Occurrence of immature Culicoides molestus (Skuse) (Diptera : Ceratopogonidae) in relation to habitat characteristics

Analysis of beach sites on the Gold Coast, Australia, found that 14 physical and chemical habitat characteristics differed significantly between sites where numerous immatures of the canal biting midge, Culicoides molestus (Skuse), were found and sites where no midge immatures occurred. Five of the chemical factors found to reliably distinguish C. molestus habitat are major components of seawater, while another, electrical conductivity, is related to the concentration of seawater components. Calcium was the only one of the six primary components of seawater that was not a statistically significant correlate of C. molestus habitation by sand analysis. It is likely that a causative variable in occurrence of immatures is the concentration of seawater present in canals, because larvae are found where seawater component concentration is low in relation to uninhabited sites of similar appearance.

Incidence, characteristics, and predictive factors for dysphagia after pediatric traumatic brain injury

Objective: (1) To establish an incidence figure for dysphagia in a population of pediatric traumatic brain injury (TBI) cases; (2) to provide descriptive data on the admitting characteristics, patterns of resolution, and outcomes of children with and without dysphagia after TBI; and (3) to identify any factors present at admission that may predict dysphagia. Participants: A total of 1, 145 children consecutively admitted to an acute care setting for traumatic brain injury between July 1995 and July 2000. Main outcome measure: Medical parameters relating to dysphagia based on medical chart review. Results: (1) Dysphagia incidence figure of 5.3% across all pediatric head injury admissions. Incidence figures of 68% for severe TBI, 15% for moderate TBI, and only 1% for mild brain injury. (2) Statistically significant differences were found between the dysphagic and nondysphagic subgroups on the variables of length of stay, length of ventilation, Glasgow Coma Scale (GCS), computed tomography classification, duration of speech pathology intervention, supplemental feeding duration, duration until initiation of oral intake (DIOF), duration to total oral intake (DTOF), and period of time from the initiation of intake until achievement of total oral intake (DI-TOF). (3) Significant predictive factors for dysphagia included GCS < 8.5 and a ventilation period in excess of 1.5 days. Conclusion: The provision of incidence data and predictive factors for dysphagia will enable clinicians in acute care settings to allocate resources necessary to deal with the predicted number of dysphagia cases in a pediatric population, and assist in predicting patients who are at risk for dysphagia following TBI. Early detection of patients with swallowing dysfunction will be aided by these data, in turn helping to facilitate effective medical and speech pathology intervention via assisting the reduction of medical complications such as aspiration pneumonia.

Prognostic use of growth characteristics of early gastric cancer and expression patterns of apoptotic, cell proliferation, and cell adhesion proteins

Background and Objectives: Selection of suitable treatment for early gastric cancers, such as endoscopic mucosal resection or the major surgical option of resection of the cancer together with a radical lymph node dissection, may be assisted by comparing the growth characteristics of the cancer with selected molecular characteristics. The results could be used to predict those cases that have a higher risk of developing secondary metastases. Methods: A total of 1,196 Japanese patients with early gastric cancers (648 mucosal cancers and 548 submucosal) were included in the selection of two groups: a metastatic group made up 57 cancers with lymph node metastasis (9 mucosal, 48 submucosal), and a nonmetastatic group of 61 cases (6 mucosal, 55 submucosal) without lymph node metastasis. Growth characteristics of the cancers (superficially spreading, penetrating or invasive, lymph node metastasis) were compared with immunohistochemical expression of single-stranded DNA (ssDNA) protein (apoptosis indicator), bcl-2 and p53 (apoptosis-associated), Ki-67 (cell proliferation), and E-cadherin (cell adhesion) proteins. Results: The lesions in the nonmetastatic group had higher levels of apoptosis and lower expression of bcl-2 than in the metastatic group, indicating an inhibitory role for apoptosis in malignant progression. Apoptosis was also higher in the superficial compared with the invasive lesions of both groups. The lesions in the metastatic group had higher p53 expression than that of the nonmetastatic group, whereas apoptosis in the metastatic group was lower than in the nonmetastatic group. An unproved explanation for this finding may be that, although increased, p53 was mutated and ineffective in promoting apoptotic control of metastatic progression. E-cadherin was decreased in the invasive lesions of both groups, indicating a greater ability of these cells to lose adhesion, to invade the submucosa, and to metastasize. Cell proliferation was highest in the superficial lesions of both metastatic and nonmetastatic groups. Conclusions: Early gastric cancers with low levels of apoptosis, increased bcl-2, and high levels of p53 expression are more likely to invade and metastasize. (C) 2003 Wiley-Liss, Inc.

Abnormal left ventricular filling with increasing age reflects abnormal myocardial characteristics independent of ischemia or hypertrophy

Abnormal left ventricular (IV) filling may occur with increasing age despite apparently normal IV size and function, and is usually attributed to IV hypertrophy and coronary artery disease. The purpose of this study was to determine whether myocardial abnormalities could be identified in 67 such patients (36 men, mean age 57 +/- 9 years) whose IV hypertrophy and coronary artery disease were excluded by dobutamine echocardiography. All patients underwent gray scale and color tissue Doppler imaging from 3 apical views, which were stored and analyzed off line. Disturbances in structure and function were assessed by averaging the cyclic variation of integrated backscatter, strain rate, and peak systolic strain from each myocardial segment. Calibrated integrated backscatter (corrected for pericardial backscatter intensity) was measured in the septum and posterior wall from the parasternal long-axis view. Abnormal IV filling was present in 36 subjects (54%). Subjects with and without abnormal IV filling had similar IV mass, but differed in age (p <0.01), cyclic variation (p = 0.001), strain rate (p <0.01), and peak systolic strain (p <0.001). Multivariate logistic regression analysis demonstrated that age (p = 0.016) and cyclic variation (p = 0.042) were the most important determinants of abnormal IV filling in these apparently normal subjects. (C) 2003 by Excerpta Medica, Inc.

Determination of the effect of lipophilicity on the in vitro permeability and tissue reservoir characteristics of topically applied solutes in human skin layers

In order to establish the relationship between solute lipophilicity and skin penetration (including flux and concentration behavior), we examined the in vitro penetration and membrane concentration of a series of homologous alcohols (C2-C10) applied topically in aqueous solutions to human epidermal, full-thickness, and dermal membranes. The partitioning/distribution of each alcohol between the donor solution, stratum corneum, viable epidermis, dermis, and receptor phase compartments was determined during the penetration process and separately to isolated samples of each tissue type. Maximum flux and permeability coefficients are compared for each membrane and estimates of alcohol diffusivity are made based on flux/concentration data and also the related tissue resistance (the reciprocal of permeability coefficient) for each membrane type. The permeability coefficient increased with increasing lipophilicity to alcohol C8 (octanol) with no further increase for C10 (decanol). Log vehicle:stratum corneum partition coefficients were related to logP , and the concentration of alcohols in each of the tissue layers appeared to increase with lipophilicity. No difference was measured in the diffusivity of smaller more polar alcohols in the three membranes; however, the larger more lipophilic solutes showed slower diffusivity values. The study showed that the dermis may be a much more lipophilic environment than originally believed and that distribution of smaller nonionized solutes into local tissues below a site of topical application may be estimated based on knowledge of their lipophilicity alone.