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At least 235 records · Page 13Linked to original sources

PubMed1996

The microvascular system in ischemic cortical lesions.

In the rat, normal blood flow can be restored in the territory of the occluded artery after an arterial occlusion. This event has been attributed to changes in the collateral vessels supplying the territory of the occluded artery. Since only a limited amount of data is available about the plasticity of the microvascular system after a cortical ischemic lesion, in the present study we have evaluated whether the restoration of blood flow to normal levels in the territory of the middle cerebral artery after permanent ischemia is due only to flow through preexisting collateral vessels or also to the development of new microvessels. Middle cerebral artery occlusion was performed in 45 rats. After 24 h of ischemia, magnetic resonance imaging was used to select 16 rats with cortical lesions of similar size and location. After 2 weeks, vascular corrosion casts were obtained from 8 rats by injection of low-viscosity resin and observed by scanning electron microscopy. A correlative light and electron microscopy study was performed using the remaining 8 rats. Two different patterns of vascular modifications were found, one dorsal and one ventral to the lesion. The dorsal portion of the lesion was vascularized by collateral arteries originating from the anterior or posterior cerebral arteries. Collateral trunks showed a meandering course, mainly in the occipital pole. In the ventral portion of the lesion a complex microvascular system was found characterized by an intense vascular proliferation. The arterioles showed a parallel, candelabrum-like pattern with dichotomic branching. Contraction rings were frequently seen. The capillaries showed a sinusoid-like structure, with a large lumen and a continuous endothelium with many micropinocytotic vesicles. A peripheral ring-shaped venous sinus was composed of a network of flat vessels. These results give the first comprehensive description of the microvascular modifications in a focal model of infarct and suggest that the restoration of blood flow to normal levels described in the territory of the middle cerebral artery after permanent ischemia may be due not only to flow through collateral vessels but also to the development of a new vascular system originating mainly from branches of the middle cerebral artery before the occlusion point.

Animals↗

PubMed2005

Three-dimensional reconstruction of the distribution of flame cells in a trematode cercaria.

In order to reveal the vertical distribution of flame cells in a trematode cercaria, horizontal serial semi-thin sections were reconstructed by an image analyzer and a manual procedure. The ascending main excretory tubes extended forward, meandering up and down at the digestive system level from the excretory bladder. At the posterior end of the ventral sucker, they curved dorsally, passed through the dorsal side, returning to the mid level at the anterior end of the ventral sucker. They then ran forward to the posterior part of the oral sucker, and turned back. The flame cells were more abundant in the ventral region than in the dorsal region. The majority of pairs of right and left flame cells were present at the same distance from the digestive system or ventral (or dorsal) surface. This method, using conventional techniques, has some advantages for determining the horizontal and vertical distributions of flame cells in cercaria and may, therefore, promote research on cercaria.

Animals↗

PubMed2002

Pit pattern and three-dimensional configuration of isolated crypts from the patients with colorectal neoplasm.

BACKGROUND: This study examined the usefulness of magnifying videoscopic pit-pattern diagnosis in the differential diagnosis of colonic neoplasms. The relationship between pit patterns and the three-dimensional configuration of the neoplastic gland was evaluated for its contribution toward an understanding of pit patterns. METHODS: A total of 3005 colorectal lesions were examined endoscopically and histopathologically. Pit patterns were classified into six types. All materials used for crypt isolation were derived from segments of 21 colorectal lesions and one normal colonic mucosa. For the crypt isolation, the HCl-digestion method was used. RESULTS: The magnifying videoscopic diagnosis was comparable with the histological diagnosis in the 3005 colorectal lesions. Isolated crypts with the type-I pit pattern resembled a test-tube; the type-II pit pattern was also tubular, but had observed fissures at the bottom; the type-III l pit pattern was a reversed triangle or tongue-like in shape; and the type-III s pit pattern was columnar and either tapered off or meandered. Isolated crypts with the type-IV b pit pattern appeared as long reversed triangles with protuberances, and the type-IV v pit pattern was flat with slender tubules or finger-like processes. The isolated crypts with the type-V pit pattern were complicated and indistinct in shape. CONCLUSIONS: Evaluation of the three-dimensional configuration revealed that when the pit patterns, of each isolated crypt differed, their three-dimensional configurations also differed. Recognition of the differences in the three-dimensional configuration should contribute toward both an understanding of pit-pattern diagnosis and the further development of the endoscopic diagnosis of various colorectal lesions.

Adenoma↗

PubMed2003

Functional recovery after simultaneous transplantation with neuro-epithelial stem cells and adjacent mesenchymal tissues into infarcted rat brain.

BACKGROUND: Cerebral infarction results in impairment of motor and cognitive functions. We performed intracranial transplantation of multipotential neuro-epithelial stem cells with mesenchyme into experimentally large ischemic lesions to study their potential to relieve deficits. METHODS: Wistar albino rats were subjected to transient middle cerebral artery occlusion for 60 minutes, producing an extensive ischemic lesion in the ipsilateral striatum and adjacent cerebral cortex. The rat mesencephalic neural plate at the early somite stage (embryonic day 10.5) together with adjacent ventral mesenchyme was used as donor material. We performed histological and immunohistochemical studies, with antibodies against tyrosine hydroxylase, and dopamine- and adenosine 3': 5'-monophosphate-regulated phosphoprotein 32 (DARPP-32; a striatal marker). Micro-angiograms were made by using Microfil silicone rubber. Morris Water-maze learning and treadmill task were employed to evaluate motor and cognitive functions. FINDINGS: A viable non-tumoral mass was recognized in the rat striatum, up to as long as 156 days after transplantation. There were many cells positive for tyrosine hydroxylase or DARPP-32 in the graft. Some of the DARPP-32 positive cells within the graft had extended their dendrites into host tissues. In the micro-angiograms, many fine vessels were observed within the graft and dilated vessels meandered around the graft. Transplanted animals recovered significantly better in motor and cognitive functions than animals injected with only culture medium. INTERPRETATION: Neuro-epithelial stem cells may follow several lines of differentiation; along the naturally genetically programmed line of differentiation, or along other cell lines depending on different environments. Grafting of neuro-epithelial stem cells with mesenchyme may merit a further study as a treatment for cerebral infarction.

Animals↗

PubMed2005

Movement behaviour of Medaka (Oryzias latipes) in response to sublethal treatments of diazinon and cholinesterase activity in semi-natural conditions.

Behavioural changes of medaka (Oryzias latipes) treated with an anticholinesterase insecticide, diazinon (0.1 mg L(-1)), were continuously observed for 4 days in semi-natural conditions. Although variations occurred in individual specimens, the movement tracks appeared differently with typical short-range movement with irregular turns and shaking after the treatments. Eight movement patterns frequently observed before and after the treatments were selected, and the variables characterising the movement patterns were compared quantitatively. The variables were clearly differentiated when the movement patterns were correspondingly matched before and after the treatments (e.g., vertical movements, horizontal movements, etc). Meander and stop duration were highly different among the selected movement patterns. Additionally, different degree of toxic response behaviours could also be detected by quantitative characterisation of the variables. Response behaviour was confirmed with toxicological experiments that show the decrease in the acetylcholine esterase activity in the head and body of specimens. Quantitative investigations on the variables of the movement tracks suggested the usefulness of response behaviour as a monitoring tool for environmental assessment.

Animals↗

PubMed1985

Morphology of axons in the human lateral geniculate nucleus: a Golgi study in prenatal and postnatal material.

A study was made of rapid Golgi preparations from the lateral geniculate nucleus in humans aged from 28 weeks gestation to 70 years in order to identify axon terminals of afferent fibre systems. We describe three main axonal types using, as far as possible, nomenclature already adopted for other species. Type I axons were found only rarely. They are relatively straight with short, stalked side-branches and may represent cortico-geniculate fibres. Type II axons have complex, ball-like arborizations with large, irregular varicosities. They are common at all ages from gestation to maturity and are probably retinal in origin. Type IV axons (Type III was not used as no unequivocally intrinsic axons, for which the term has been used in the past, were identified) are branched, meandering and characterized by many, regular varicosities. Their origin is unclear, but may be related to non-specific brainstem sources. The basic morphology of Type II axons varies little between late gestation and adulthood, but Types I and IV seem to evolve during the perinatal period, perhaps from primitive forms that have similar morphological features. We conclude that the morphology of afferent axons to the human lateral geniculate nucleus is basically similar to that of lower mammalian species.

Adolescent↗

PubMed1995

A rapid non-selective method to generate quadromas by microelectrofusion.

A simple non-selective methodology was developed and standardized to generate desired hybrid-hybridoma or quadroma secreting bifunctional antibodies. This novel protocol is based on microelectrofusion on a meander chamber using a few hundred cells of each of the two parental hybridomas with no laborious drug selection procedures. Seeding approximately 10 cells per well in a 96-well microtitre plate after fusion in 200 microliters standard medium containing 20% FBS and 10% Origen growth factor generated positive quadromas secreting bispecific antibodies with good stability after the second reclone. Compared to the conventional PEG fusion and other methods this simple protocol is both rapid and economical. Generally, conventional methods to make quadromas and triomas require the introduction of drug selection markers into one or both of the parental cells, a procedure that could take 3-6 months. Utilizing the non-selective microelectrofusion method described here, we have generated several quadromas in a very short time. Further, such a protocol could also be potentially adopted to generate human hybridomas with few B cells isolated from peripheral blood lymphocytes enriched by antigen specific panning or affinity microelectrofusions.

Animals↗

PubMed1990

Origin, course, and endings of abnormal enteric nerve fibres in Hirschsprung's disease defined by whole-mount immunohistochemistry.

Accurate delineation of the intramural pathway of abnormal enteric nerve fibres in Hirschsprung's disease has previously proved impossible because the neural network is invariably transected in conventional histological sections. With the technique of wholemount immunohistochemistry (WI), the bowel segment is converted into a rectangular sheet and the serosa, long muscle (LM), circular muscle (CM), submucosa, and mucosa are separated into layers to allow each nerve plexus to be examined intact and neural pathways traced. The entire resected bowel specimens of nine HD infants and five infants serving as controls were investigated, using neuron-specific enolase and vasoactive intestinal peptide (VIP) for WI. The major new findings are (1) More VIP fibres were observed in aganglionic bowel with WI than with conventional sections; (2) Thick nerve trunks in aganglionic bowel do not descend from intrinsic neurons of oligoganglionic bowel as previously suggested, but have an extrinsic origin, accompanying blood vessels as small nerves initially, expanding subsequently, and ending blindly in submucosa; (3) CM nerve fibres follow muscle fibres concentrically for long distances in aganglionic bowel; and (4) LM nerve fibres meander in spirals in aganglionic bowel instead of running straight. This study shows that (1) WI is highly sensitive; (2) nerve fibres in aganglionic bowel have an extrinsic origin; and (3) innervation abnormalities in Hirschsprung's disease are not only quantitative but qualitative.

Colon↗

PubMed1990

The relation of periportal fibrosis to portal hypertension.

To clarify the relation of periportal fibrosis to portal hypertension, the present study was undertaken in rats given lithocholate. Portal vascular resistance measured by an isolated liver perfusion method increased with the length of lithocholate administration. In vivo portal vein pressure elevation was closely correlated to the increase in portal vascular resistance. The blood pressure difference between the portal vein and the terminal portal venule increased compared to control rats. The blood pressure differences between the terminal portal venule and the terminal hepatic venule, and between the terminal hepatic venule and the inferior vena cava, were almost the same as those in control rats. Lithocholate administration induced narrowing and meandering of the portal vein branches due to periportal fibrosis with proliferation of bile ductules. There was no perceptible change in the sinusoids and the hepatic vein branches. These data suggest that periportal fibrosis causes deformation of the peripheral branches of the portal vein and leads to presinusoidal portal hypertension.

Administration, Oral↗

PubMed1989

The making of a sociomedical scientist (Jack Elinson).

Publishing this festschrift for Jack Elinson in Social Science and Medicine is especially appropriate at this time, not only because it gives an opportunity to those who have known him for many years to express their appreciation of his many significant contributions as a scientist and humanist, but also because an exploration of the influences which contributed to his successful career should provide further insight into what it takes to be able to be effective in breaking new ground in the sociomedical sciences. The notes which follow are written from the standpoint of one who has been a personal friend of Jack's over a 40-year span, sharing many of the same types of experiences in meandering toward a career during the pioneering stages of bringing scientific method to bear in the development of public opinion and behavior sampling surveys beginning in the mid-1930s.

History, 20th Century↗

PubMed1995

Elements of a systematic search in animal behavior and model simulations.

Starting from a position paper by Hans Bremermann, general aspects of search behavior are envisaged: locomotion itself, the capability of orientation and possible storage of information about the 'goals' of a search. The importance of stochasticity in these processes is briefly discussed. In particular, experimental findings and theoretical concepts on the homing search of desert isopods (Hemilepistus reaumuri) are presented. Using the general framework of stochastic differential equations for the angular turning rate of a migrating individual, search paths with characteristic loops and meanders can be modelled and simulated. Search success is quantified by measuring the degree of path overlap and by computing an index of area search intensity. Quantities are plotted versus path length, both for observed isopod data and for typical simulated search paths. Certain elements of a systematic search are described and explained by a hypothesis about temporal locomotion control, based on the isopod's ability for path integration and directional compensation. Finally, possible effects of orientational cues are mentioned.

Animals↗

PubMed1985

Substance P-containing sensory nerves in the rat iris. Normal distribution, ontogeny and innervation of intraocular iris grafts.

Trigeminal, substance P-containing nerves have been studied in the stretch-prepared rat iris with immunohistochemical techniques. The normal iris exhibited a slightly irregular plexus of individual fibres in the dilator, intermingled with thin, meandering axon bundles. The sphincter contained more circumferentially oriented fibres. Occasional free nerve endings were present in all parts of the iris; no obvious association with blood vessels was detected. All substance P-positive nerves in the iris disappeared after lesioning the trigeminal nerve. Irides of neonates showed scattered, smooth fibres in a sparse plexus, without visible axon bundles. Over the first two postnatal weeks, the density of innervation developed rapidly, reaching a transiently supranormal level and fluorescence intensity, compared to adulthood. From 3 weeks on, the pattern and density of substance P-containing fibres approached the normal adult appearance. In irides grafted to the anterior eye chamber, the intrinsic substance P nerves degenerated, disappearing completely after 5 days. Reinnervation from the host irides transpired over the next few weeks, approximating normal density after 3 weeks, and organotypic density and distribution from 4 weeks on. No obvious hyperinnervation was encountered after longer postoperative times (3 months). In the host iris, many substance P fibres disappear or exhibit low fluorescence intensity during the first postoperative week, recovering fully during the next 2 weeks. Over longer postoperative periods irregular, moderate hyperinnervation developed with increased numbers of axons in bundles. In conclusion, we show normal distribution and plasticity during ontogeny and maturity of substance P-containing iris nerves in the rat, with a sensitive immunohistochemical technique in iris whole mounts.

Animals↗

PubMed1983

Serotonergic interactions with rat cerebellar Purkinje cells.

Recent immunocytochemical and histofluorescent studies have established the vastness of the serotonergic fibers arising from the raphe complex and projecting to the cerebellar cortex. Ultrastructurally, the indoleaminergic fibers are known to establish synaptic contacts as well as diffuse meandering nonsynaptic terminations near Purkinje cells. The objective of this study was to define the changes elicited by serotonin on spontaneous and chemically- and electrically-evoked excitatory synaptic activities on cerebellar Purkinje cells. Serotonin (10-50 nA) applied for 30-60 sec elicited predominantly a decrease in firing rate followed by rebound excitation (25 cells out of a total of 39 cells). Studies in which serotonin was continuously iontophoresed for prolonged periods, this amine produced an increase in the spontaneous firing rate in 55% of the Purkinje cells tested. A comparison of evoked excitation and spontaneous activity revealed that when serotonin was applied continuously there was a net decrease in evoked excitation to spontaneous activity ratio. Based on the evoked excitation studies, glutamate (5-30 nA) was applied for 30-40 sec in the presence of serotonin (10-30 nA). Seventy-seven percent of the cells displayed a decrease in responsiveness to glutamate while the remaining 23% were potentiated. More definitive explanation of these results are given in the body of the test.

Action Potentials↗

PubMed1993

Alpha plus beta folds revisited: some favoured motifs.

BACKGROUND: By performing extensive pairwise structural comparisons, we recently identified a set of unique folds from the Brookhaven protein structure data bank. This analysis revealed considerable similarities between a large subgroup of the alpha+beta folds, which led us to re-examine the types of folds occurring in this class and the nature of the relationships between them. RESULTS: Two major alpha+beta fold groups can be distinguished. In the first, described as alpha-beta sandwiches because alpha-helices and beta-strands occupy separate and distinct layers, a split beta alpha beta motif recurs frequently. The other group, alpha-beta rolls, contains fewer helices and is more diverse. In these, the beta-sheet has folded or rolled over, providing a cradle for the alpha-helix. A beta beta beta alpha-meander motif is found throughout the alpha+beta class. CONCLUSION: Although many alpha-beta sandwiches have very similar folds, few share common functions and the active sites are distributed over the whole surface of the fold. The ability of the alpha-beta sandwich to accommodate a range of functions suggests that it is a stable fold and one that is able to adapt a number of sites to satisfy different functional requirements. In contrast, amongst the alpha-beta rolls, folds having the same roll type often have common functions.

Animals↗

PubMed2004

Functional characterization of four allelic variants of human cytochrome P450 1A2.

Human cytochrome P450 1A2 catalyzes important reactions in xenobiotic metabolism, including the N-hydroxylation of carcinogenic aromatic amines. In 2001, Chevalier et al. reported four new P450 1A2 sequence variants in the human population. We have now expressed these variants in Escherichia coli and measured protein expression (optical spectroscopy of holoenzyme and immunoblotting) and bioactivation of IQ (2-amino-3-methylimidazo[4,5-f]quinoline) and MeIQ (2-amino-2,4-dimethylimidazo[4,5-f]quinoline) in the lacZ reversion mutagenicity test. Enzyme kinetic analyses were performed for N-hydroxylation of five heterocyclic amine substrates and for O-deethylation of phenacetin. The most drastic effect was that of the R431W substitution: no holoenzyme was detectable. This residue is located in the "meander" peptide region and earlier site-directed mutagenesis studies demonstrated that it is critical for maintenance of protein tertiary structure. The other three variants had subtly different catalytic activities compared to the wild-type enzyme.

Alleles↗

PubMed2006

Persistence of Cloquet's canal in normal healthy eyes.

PURPOSE: Optic nerve head (ONH) structural imaging with state-of-the-art, high-speed, ultra-high-resolution optical coherence tomography (hsUHR-OCT). DESIGN: Observational cohort study. METHODS: ONH centered 3-dimensional (94,371,840 voxel measurements in a 6- x 6- x 1.4-mm tissue volume) hsUHR-OCT data were obtained in one eye from each of six males and nine females normal healthy volunteers (40 +/- 9 years of age). The presence of structures projecting anteriorly from the disk into the vitreous was noted. RESULTS: Structures were noted in 14 of 15 (93%) examined eyes, emanating from the rim of the ONH at the nasal inferior sector, presenting as thin tissue meandering into the vitreous. CONCLUSIONS: Previous technologies provided limited visualization of ONH structures. The ability to scan the entire disk using 3-dimensional OCT (3D-OCT) in a high-density raster pattern reveals a high frequency of persistence of Cloquet's canal in the normal healthy eye.

Adult↗

PubMed2004

Signal-averaged electrocardiogram in Ebstein's anomaly.

We sought to establish pathogenetic links between electrophysiology, histopathology, and ventricular tachyarrhythmias in patients with Ebstein's anomaly. The atrialized right ventricle (ARV) is the site of mechanically inducible ventricular tachyarrhythmias, but relations between the arrhythmogenic substrate, the type of tachyarrhythmias, and the trigger(s) have not been established. This study comprised 23 patients (10 men and 13 women; aged 18 to 58 years; mean 32 +/- 3) who did not undergo surgery and 6 pre- and postoperative patients with Ebstein's anomaly, diagnosed by transthoracic and transesophageal echocardiography. Twenty-one patients had classic Ebstein's anomaly and 2 had mild forms. Signal-averaged electrocardiograms (SAECGs) identified slow conduction by using 3 time-domain variables calculated by an automated algorithm and inspected visually. Two variables were required to establish the presence of late potentials. SAECGs were repeated in 6 patients after surgical exclusion of the ARV. Five surgical specimens of the ARV and the true right atrium were examined histologically. Mathematic simulations were used to illustrate anchored and unanchored spiral/scroll waves. SAECGs were positive in 21 patients with classic Ebstein's anomaly and were negative postoperatively in the 6 so studied. The ARV was characterized histologically by clusters of cardiomyocytes isolated within a fibrous matrix. We hypothesize that SAECGs identify slow conduction residing in the ARV, and that excitation of this arrhythmogenic substrate provokes spiral/scroll waves that cannot anchor because clusters of cardiomyocytes are isolated within a fibrous matrix. The waves meander erratically as polymorphic ventricular tachycardia or break up into ventricular fibrillation.

Adolescent↗

PubMed2005

Computational characterization of behavioral response of medaka (Oryzias latipes) treated with diazinon.

The behavior of indicator specimens in response to sub-lethal doses of toxic substances has been used to detect contamination in aquatic ecosystems. Changes in the movement behaviors of medaka (Oryzias latipes) were analyzed after being treated with diazinon at a concentration of 0.1 mg/l. The movement tracks of medaka were continuously recorded in two-dimension by a digital image processing system both before and after the treatments. Subsequently, two computational methods--two-dimensional fast Fourier transform (2D FFT) and self-organizing map (SOM), were implemented to extract information from the movement data. The differences in the shapes of the movement tracks before and after the treatments were clearly manifested through 2D FFT. The short-distance, irregular turnings in the movement tracks observed after the treatments in the time domain were characteristically transformed to circular or ellipsoidal patterns in the frequency domain. The amplitudes of 2D FFT were efficiently classified by SOM, demonstrating the effects of the different treatments. To evaluate the feasibility of information extraction by 2D FFT, SOM was similarly carried out on the parameters (speed, meander, stop duration, etc.) conventionally used for characterizing the movement tracks. 2D FFT was more efficient in information extraction from the movement data than the parameters. The 2D FFT and SOM were useful as computational methods for automatically detecting response behaviors of indicator specimens exposed to toxic chemicals in aquatic ecosystems.

Animals↗