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PubMed1975

Topography and topology in functional recovery of regenreated sensory and motor systems.

Motor and sensory nerves can re-establish coordinated movement and accurate sensation when they regrow into denervated tissues of some lower vertebrates. Motor nerves achieve their end by a competitive process in which each motoneuron innervates many muscle fibres but, in the presence of many applicants, only those synapses from motoneurons most appropriate to a muscle cell, with respect to the original pattern of development, are retained in a functional state. The discharge pattern of a motoneuron, determined by its connections with the network of central interneurons, is not sensitive to the location of the muscles in which the axon terminates, but the efficacy of transmission from the terminals is. Sensory nerves re-establish their functional specificity as to receptor type by an inductive process occurring at the terminals along with the cessation of growth. However, in the case of cutaneous nerves they can terminate anywhere over the skin surface. The return of correctly localized reflex behaviour therefore demands a restructuring of the central nervous system in response to local position-specific signals, presumably of developmental origin, that are supplied to the sensory nerves by the skin. The re-arrangement of the central nervous connections made by the central processes of the sensory neurons probably uses the same competitive mechanism of enabling and disabling formed synaptic connections as is used in sorting out the correct site of functional termination of the peripheral processes of motoneurons.

Animals↗
PubMed2001

Canadian Aboriginal communities and medical service patterns for the management of injured patients: a basis for surveillance.

Growing attention has been placed on injury as a major public health problem which has served to highlight the need for relevant injury data for preventive purposes at the community level. In the case of reserve-based Aboriginal communities in Canada, available injury data, from large datasets, often has little or no relevance at the community level. In addition, the availability of local data is complicated by unique health service and community infrastructures. As such, a prerequisite to establishing injury surveillance requires an understanding of Medical Service Patterns (MSPs) for injured patients intrinsic to a community's health service infrastructure. In determining patterns, cultural and environmental contexts are integral to methodological considerations as historically, Canada's Aboriginal population has been 'controlled' by others in the areas of health, education and social services. The objective of the study was to investigate MSPs in a Canadian Aboriginal community, specific to the management of injured patients, for the purpose of identifying data sites, sources, and collectors. The method relied on a four-step qualitative process designed explicitly for the study community, comprising: (1) semi-structured interviews with key informants; (2) a flow diagram process; (3) focus group discussions; and (4) a summary matrix diagram. This methodology was later replicated with three additional pilot communities. Three major MSPs were identified from nine original patterns generated through the initial data collection process. MSPs were found to be most directly impacted by severity of injury and the proximity of health service providers. Data collection practices were inconsistent, sporadic and poorly coordinated. Data was exclusive to respective data sources and off-reserve documentation was not reported back to the community. MSPs identified key data sites, sources, and collectors relevant to the study population. In conclusion, the four-step qualitative methodology employed in the study was found to be reliable and feasible in identifying community MSPs. Empirical findings confirm the need to investigate MSPs in communities considering surveillance activities, as intra-national differences may be considerable given social inequalities, geographic uniqueness and cultural factors. The use of sophisticated methodologies may detract rather than promote collaborative efforts.

Alberta↗
PubMed1996

Different protein patterns derived from follicular fluid of mature and immature human follicles.

The purpose of our study was to compare the protein patterns originating from fluids of mature and immature human follicles in order to gain further insight into their biochemical composition. A total of 10 patients were stimulated for in-vitro fertilization (IVF) using different stimulation protocols. Follicular fluids were aspirated transvaginally and analysed microscopically for the presence of oocytes. Follicular fluids were stored at -18 degrees C. Samples of 500 microliters were processed for two-dimensional gel electrophoresis. Up to 60 proteins in various groups could be detected. Seven protein spots were selected for chemical analysis by cutting them out of the gels and subjecting them to internal amino acid sequencing procedures. Our results can be summarized as follows: (i) major differences were not detected between the protein patterns from the various mature follicles of a particular patient, nor were significant differences observed in the proteins derived from follicular fluids collected from the seven patients with mature follicles; (ii) considerable differences were observed in the protein patterns derived from fluids of immature compared with mature follicles. Fluid from the three patients with immature follicles contained many fewer proteins, some of which were expressed at low levels. We conclude that the observed variations in protein composition of follicles of different developmental age reflect their physiological condition and serve as biomedical markers for follicular maturity.

Amino Acid Sequence↗
PubMed1993

Effects of a magnesium-deficient diet on sleep organization in rats.

The influence of magnesium, one of the most important cations in the vertebrate body, on the sleep-wakefulness cycle and ECoG patterns in chronically implanted rats recorded during the light period over a 6-hour period was investigated. Two groups of rats were studied. Group 1 (6 rats): after a control period of 2 weeks, the rats were maintained for 9 weeks on a Mg(2+)-deficient diet. Group 2 (5 rats): after a control period of 2 weeks, the rats were maintained for 7 weeks on a Mg(2+)-deficient diet followed by 4 weeks on a normal diet (recovery period: weeks 8-11). Mg(2+)-deficient diet for 9 weeks induced sleep and ECoG time-dependent alterations. After 6-7 weeks on a Mg(2+)-deficient diet (n = 11) sleep analysis showed a significant increase of wakefulness (+50%) at the expense of slow wave sleep (-24%) but paradoxical sleep was not significantly modified. After 9 weeks of a Mg2+ deficient diet, sleep was disorganized: light sleep and polyspikes occurred indicating an increase in neuronal excitability. When Mg2+ was reintroduced in food and water, sleep organization and ECoG recordings were restored to their original patterns. Our findings which are in line with previous clinical and pharmacological observations provide conclusive arguments for the neuroprotective effect of magnesium ions in neurologic disorders and epileptiform activity. Mg2+ deficiency induces ECoG alterations in the rat which bear some similarities with those seen in neurogenic spasmophilic syndromes in man.

Animals↗
PubMed1998

Beyond black, white and Hispanic: race, ethnic origin and drinking patterns in the United States.

This study used data on 42,862 U.S. adults, including 18,352 past-year drinkers, to describe differentials by race and national origin in U.S. drinking patterns. Age-sex standardized estimates were presented within 21 categories of ethnic origin for whites and within five categories each for individuals of black and other races. Of the three racial groups, whites were the most likely to drink, but blacks had the highest volume of intake and frequency of heavy drinking. Differences by ethnic origin within racial categories were as marked as differentials between races. Compared to whites of European origin, those of Hispanic and native American origin were less likely to drink but consumed more alcohol on days when they drank. Whites of Southern and Eastern European origin drank proportionately more wine and demonstrated more moderate drinking patterns (lower intake per drinking day and/or less frequent heavy drinking) than those of Northern or Central European origin. Hispanics of Caribbean origin were less prone to heavy drinking than other white Hispanics; similarly, blacks from the English-speaking Caribbean showed more moderate drinking patterns than other blacks. Individuals of Asian origin, in particular those of non-Japanese origin, had the most moderate drinking patterns within the category of other race. Although the black/white differentials in volume of intake and frequency of heavy drinking disappeared after adjusting for marital status, education and income, most of the differences by ethnic origin retained their statistical significance if not their original magnitudes. These findings indicate that cultural forces exert a strong effect on drinking behavior. Differences among European whites with respect to prevalence of drinking, beverage preference and frequency of heavy drinking suggest that the association between ethnic origin and drinking behavior may persist even after many generations of presumed acculturation.

Acculturation↗
PubMed1997

Reestablishment of the olivocerebellar projection map by compensatory transcommissural reinnervation following unilateral transection of the inferior cerebellar peduncle in the newborn rat.

It is unclear whether reparative processes in the injured mammalian brain are able to restore the topographic organisation of neuronal connections. To address this question, we have investigated the plasticity of the olivocerebellar system. This pathway has a precise topographic arrangement, in which subsets of inferior olivary neurons project to parasagittally oriented Purkinje cell compartments. Following unilateral transection of the inferior cerebellar peduncle in newborn rats, axons from the contralateral projection cross the cerebellar midline and reinnervate the deafferented hemicerebellum. By this experimental approach, we first analysed the behaviour of calcitonin gene-related peptide (CGRP)-immunoreactive climbing fibres. This marker is transiently expressed by a subset of developing inferior olivary axons, which terminate in the cerebellar cortex into several parasagittal strips. We show that transcommissural axons reestablish the original pattern of climbing fibre bands within a few days after lesion. Then, in adult animals injured at birth, we assessed whether the newly formed climbing fibre bands align with zebrin II+/- Purkinje cell compartments, as in normal conditions. The newly formed projection is organised in parasagittally oriented strips which mirror the distribution of their counterparts on the intact side and are precisely aligned to the heterogeneous Purkinje cell compartments. In addition, the patchy distribution of olivo-nuclear fibres suggests that specific reinnervation is also achieved in the deep nuclei. Thus, transcommissural olivocerebellar reinnervation is not random, but it is regulated by selective interactions between distinct subsets of olivocerebellar axons and target neurons aimed at reestablishing the correct projection map.

Animals↗
PubMed1996

Expression and regulation of brain-derived neurotrophic factor and neurotrophin-3 mRNAs in distinct avian motoneuron subsets.

We performed a detailed study of the expression of neurotrophin-3 and brain-derived neurotrophic factor transcripts in spinal motoneurons using in situ hybridization of serially sectioned chick embryos aged 3 to 8 days (E3 to E8). Neurotrophin-3 mRNA is detected in motoneuron subsets from E3.5 to E4 only in brachial segments of the neural tube and from E5 in both brachial and lumbar regions. Expression of brain-derived neurotrophic factor mRNA is first evident on E5 in a subset of brachial level motoneurons and from E6 also in motoneurons located in the rostral-most portion of the lateral motor column, as well as in the tail-innervating region of the spinal cord. Analysis along the rostrocaudal extent of the brachial lateral motor column reveals an overlap zone of expression of both neurotrophins of about two segments. In transverse sections of this region, it is observed that neurotrophin-3-positive motoneurons preferentially occupy the lateral part of the column, whereas brain-derived neurotrophic factor-producing motoneurons are localized in a more medial position. These results show that the two factors are synthesized at discrete axial levels of the spinal cord by distinct motoneuron subpopulations. Since brain-derived neurotrophic factor mRNA is expressed within the brachial but not the lumbar lateral motor column, we tested the possibility that brain-derived neurotrophic factor expression is regulated by the type of peripheral target, that is, the wing or the leg. Unilateral transplantation of a wing bud instead of a leg bud and vice versa, prior to the onset of peripheral innervation, failed to alter the original pattern of brain-derived neurotrophic factor mRNA observed in either level of the axis. Thus, the early synthesis of brain-derived neurotrophic factor by subsets of spinal motoneurons is independent of the type of peripheral target and may instead reflect intrinsic differences between motoneuron populations.

Animals↗
PubMedDate not supplied

Fragile X mental retardation: prevalence in a group of institutionalized patients in Italy and description of a novel EEG pattern.

We have studied the prevalence of the fra (X) and of the autosomal fragile sites fra (10) (q25) and fra (16) (q22) in patients from an institute for the mentally retarded in Italy. We found six cases (1.9%) of fra (10) (q25) and 9 (2.9%) of fra (16) (q22). The study of the fra (X) was restricted to a subgroup of 91 males who did not have other chromosome anomalies or variants, and led to the discovery of 4 fra (X) cases. These 4 had the Martin-Bell syndrome; 3 of them were epileptic and had a characteristic EEG pattern originating during sleep from the temporal lobe not previously described in fra (X) mental retardation.

Adolescent↗
PubMed1993

Is segmentation generic?

When two populations of cells within a tissue mass differ from one another in magnitude or type of intercellular adhesions, a boundary can form within the tissue, across which cells will fail to mix. This phenomenon may occur regardless of the identity of the molecules that mediate cell adhesion. If, in addition, a choice between the two adhesive states is regulated by a molecule the concentration of which is periodic in space, or in time, then alternating bands of non-mixing tissue, or segments, can form. But temporal or spatial periodicities in concentration will tend to arise for any molecule that is positively autoregulatory. It is therefore proposed that segmentation is a 'generic' property of metazoan organisms, and that metamerism would be expected to have emerged numerous times during evolution. A simple model of segmentation, based solely on differential adhesion and periodic regulation of adhesion, can account for segment properties as disparate as those seen in long and short germ band insects, and for diverse experimental results on boundary regeneration in the chick hind brain and the insect cuticle. It is suggested that the complex, multicomponent segment-forming systems found in contemporary organisms (e.g., Drosophila) are the products of evolutionary recruitment of molecular cues such as homeobox gene products, that increase the reliability and stability of metameric patterns originally templated by generic self-organizing properties of tissues.

Animals↗
PubMed2003

Powder pattern indexing using the weighted crosscorrelation and genetic algorithms.

X-ray diffraction is a powerful technique for investigating the structure of crystals and crystalline powders. Unfortunately, for powders, the first step in the structure elucidation process, retrieving the unit cell parameters (indexing), is still very critical. In the present article, an improved approach to powder pattern indexing is presented. The proposed method matches peak positions from experimental X-ray powder patterns with peak positions from trial cells using a recently published method for pattern comparison (weighted crosscorrelation). Trial cells are optimized with Genetic Algorithms. Patterns are not pretreated to remove any existing zero point shift, as this is determined during optimization. Another improvement is the peak assignment procedure. This assignment is needed for determining the similarity between lines from trial cells and experiment. It no longer allows calculated peaks to be assigned twice to different experimental peaks, which is beneficial for the indexing process. The procedure proves to be robust with respect to false peaks and accidental or systematic absensences of reflections, and is successfully applied to powder patterns originating from orthorhombic, monoclinic, and triclinic compounds measured with synchrotron as well as with conventional laboratory X-ray diffractometers.

Journal Article↗
PubMed1992

Strains and forces in selected carpal ligaments during in vitro flexion and deviation movements of the hand.

The forces induced in tiny wrist joint ligaments must be estimated in order to understand their role in the mechanism of the joint. We estimated forces in a number of selected ligaments in seven human wrist joint specimens, using a noninvasive method. The method is based on the rationale that the force generated in a ligament depends on its change of length with the joint under load. In vitro length changes of the ligaments were determined during flexion and deviation movements of the hand, using a roentgenstereophotogrammetric analysis technique. Subsequently, bone-ligament-bone (BLB) preparations were dissected from the specimens. From these BLB preparations the zero-force length and the force-elongation relationship were determined in a material testing machine. The forces generated in the ligaments during flexion and deviation were calculated by combining results on the in vitro ligament length changes, the zero-force length, and the force-elongation relationship. Large interspecimen variations of the force patterns were found. Due to this variability, it is not possible to obtain quantitative models for the kinetic behavior of the ligaments. However, qualitative trends could be distilled from the strain and force patterns. It is clear that for most ligaments, the zero-force lengths were not equal to the lengths they possessed in the neutral position of the hand. Furthermore, it could be shown which motions of the hand would most likely strain a particular ligament. It could be shown that the variations in the force patterns originate mainly from variations in the zero-force lengths, and from variations in the force-strain relationship between specimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Regeneration of neuromuscular connections in crayfish allotransplanted neurons.

Transplantation of whole ganglia was used to study the regeneration of four of the neurons that innervate the superficial flexor muscles of the crayfish Procambarus clarkii. The isolated ganglia containing the somas of these neurons were successfully transplanted from one crayfish to another. Reinnervation proceeded across the muscle surface and by 8 to 10 weeks connections were detected across the entire target field. At different time periods after the transplant, junction potentials (JPs) produced in phase with spontaneous neuronal spikes were recorded. The distribution of JP sizes and their decay times were examined. JPs from transplanted preparations were smaller than JPs from control or normal regeneration animals. These JPs also failed to facilitate when stimulated at 1 and 10 Hz. These are normal characteristics of immature terminals, but in the transplant preparations, once established, they remained stable for the duration of the study. Thus, synaptogenesis appears to be arrested at a stage before synaptic efficacy is established in the allotransplants. In addition, connectivity maps were plotted for each axon over the muscle surface. Some muscle fibers did not receive any contacts, and overall innervation leveled off at around 60% of the muscle fibers, remaining stable for the duration of this study. Despite the incomplete physiological innervation, however, three of the four neurons showed the same medial/lateral preferences observed in control animals, regenerating their original patterns of connectivity across the muscle surface.

Animals↗
PubMed1993

Co-localization of components of the protein-synthesizing machinery with the cytoskeleton in G0-arrested cells.

The distribution of eukaryotic elongation factor 2 (eEF-2) in G0-arrested fixed human skin diploid fibroblasts was studied by indirect immunofluorescent microscopy. It was found earlier that the main part of eEF-2 in cycling cells was located near the nucleus in the endoplasm (Gavrilova et al., 1987). It has been demonstrated here that the transition from proliferation to the G0 phase of the cell cycle leads to the distribution of eEF-2 mainly along the intermediate filaments and/or microtubules. Both in cycling and in G0-arrested fibroblasts a portion of eEF-2 is also co-localized with actin microfilament bundles. The reversion of the cells from the G0 phase to proliferation is accompanied by rearrangement of the actin cytoskeleton and reversal to the original pattern of eEF-2 distribution. It is likely that the different types of cytoskeleton in eukaryotic cells can be involved in organization of protein-synthesizing machinery.

Actins↗
PubMed1995

The effect of sterols and brefeldin A on protein degradation in UT-1 cells.

UT-1 cells, a mutant Chinese hamster ovary (CHO) cell line induced to produce an abundance of the enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR), were used to determine the effects of sterols and brefeldin A on the degradation of this enzyme. Brefeldin A has been shown to cause retention of proteins in and relocation of proteins to the endoplasmic reticulum (ER). UT-1 cells were incubated with (a) sterols only (12 micrograms/ml cholesterol and 0.2 microgram/ml 25-hydroxycholesterol), (b) sterols and brefeldin A (0.5 microgram/ml), and (c) brefeldin A only. Western blot analysis showed that incubation with sterols and brefeldin A decreased HMGR levels more slowly than incubation with sterols alone over the first 24-36 h of incubation; however, the rates were not significantly different. By 48 h of incubation, HMGR had decreased to a level comparable to that found when cells were incubated in sterols only. Incubation with brefeldin A alone did not cause a decrease in HMGR over the same 48-h time period. HMGR was undetectable in parental CHO cells under all of the conditions described. Indirect immunofluorescence microscopy revealed a pattern of tight, perinuclear staining with sterol incubation. After 48 h in sterols, HMGR staining was uniformly decreased throughout the cytoplasm. This change in staining pattern is also observed during incubation of UT-1 cells with sterols and brefeldin A. Incubation for 48 h with brefeldin A alone had no effect on the tight perinuclear pattern originally observed. Diffuse, faint staining of CHO cells under all conditions served as a negative control. The results of these experiments indicated that brefeldin A, and therefore retention of proteins in the ER, does not interfere with the degradation of HMG CoA reductase. Despite the presence of brefeldin A, sterol-mediated dispersal and degradation of the crystalloid ER (CER) continued in UT-1 cells. Lack of brefeldin A sensitivity implied that the mechanism for CER dissolution was distinct from previously described mechanisms for ER to Golgi transport.

Animals↗
PubMed1981

Quantitative topography of organelles in the liver. A combined histochemical and morphometric analysis.

After seven days of feeding fructose the liver of Wistar rats showed enormous accumulations of glycogen, which completely altered the original pattern of distribution of organelles. A quantitative morphological method was used to analyze these changes. The cytoplasm was mapped into arbitrary "distance classes" corresponding to concentric rings beginning at the outer nuclear membrane. This allowed the density of organelles in a given zone to be estimated. In cells filled with glycogen as a result of the fructose feeding, the following rearrangements were found: in the intermediate zone of both cellular poles (i.e., bile canalicular pole and sinusoidal pole) the mitochondria disappeared, being replaced by glycogen. The endoplasmic reticulum was accumulated in the perinuclear zone of both cellular poles, as in control animals, but was reduced throughout the rest of cytoplasm. It showed a peripheral density maximum at the biliary canalicular pole, in contrast to the cells of control animals. These changes in the distribution of the organelles and cellular "compartments" correspond to histochemical findings and demonstrate an adaptive reaction in the liver parenchyma to fructose ingestion, the organelles arranging themselves in cytoplasmic regions which still show a metabolic activity.

Animals↗
PubMed1995

Middle fossa sub-Gasserian ganglion approach to clivus chordomas.

A modified lateral subtemporal, transpetrous apex and sub-Gasserian ganglion approach was found to be most suitable for clival chordomas. The approach selection was based on the typical anatomical relationship of chordomas in terms of site of origin, pattern of growth and neural and vascular displacements. The approach was suitable to deal with tumour anterior and lateral to the brain stem, the clival part of the tumour and its sub-cavernous sinus extensions. The carotid artery was under control. The approach had the advantage of being simple and relatively quick and of its familiarity to general neurosurgeons. The tumour could be excised radically and extension of anterior, posterior and inferior exposure was possible.

Adult↗
PubMed1992

Epidemiological survey of multiple sclerosis in Catania city.

The findings of an epidemiological survey of multiple sclerosis (MS) in the urban area of Catania reveal a new and in some respects original pattern of MS cases recorded on 31 December 1989 (prevalence day). They explain why special attention should be paid to patients residing in that area, which shows a remarkable upward trend of the MS prevalence rates calling for further study and for more targeted intervention in the fields of prevention, treatment and rehabilitation.

Adolescent↗
PubMed2001

Computer-assisted design of the sagittal shapes of a ligament-compatible total ankle replacement.

The poor results of total ankle replacement have been attributed to the inability of designers to restore adequately the critical mutual function of the ligaments and the articular surfaces. The purpose of this study was to design sagittal shapes of the articular surfaces for a new ankle prosthesis to be compatible with the geometry of the retained ligamentous structures. Several ligament-compatible pairs of articular surfaces were tested using a computerised version of a four-bar linkage model. The kinematics of the ankle when replaced by non-conforming two-component and by fully conforming three-component designs with either flat, concave or convex tibial surfaces were assessed by the model. A ligament-compatible convex-tibia fully-congruent three-component prosthesis showed the best features. The three-component prosthesis allows complete congruence over the entire range of flexion. A convex shape for the tibial arc was preferred because of the better degree of entrapment of the meniscal bearing. A 5 cm convex-tibia arc radius gave 2 mm entrapment together with 9.8 mm of tibial bone cut. Ligament elongation imposed by full congruence of the articular surfaces was less than 0.03% of the original length. The original patterns of joint kinematics and ligament tensioning are closely restored in the joint replaced by the proposed prosthesis.

Ankle Joint↗