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1.
Addict Behav ; 112: 106649, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-32979691

RESUMEN

OBJECTIVE: Substance use disorders (SUD) are frequently comorbid with other psychiatric conditions, but a comprehensive diagnostic assessment is often not feasible clinically. Efficient psychometrically-validated screening tools exist for commonly comorbid conditions, but cutoff accuracies have typically not been evaluated in addiction treatment settings. This study examined the performance of several widely-used screening measures in relation to diagnostic status from a clinical interview to identify and validate cutoff scores in an inpatient SUD treatment setting. METHOD: Participants were 99 patients in a large residential SUD treatment program in Ontario, Canada. Participants completed a screening battery, including the Patient Health Questionnaire - 9 (PHQ-9), Generalized Anxiety Disorder - 7 (GAD-7), and Post-Traumatic Stress Disorder Checklist-5 (PCL-5), and underwent a semi-structured diagnostic clinical interview. Receiver operating characteristic curves were used to determine optimal cutoff scores on the screening tool against the interview-based diagnosis. RESULTS: Area under the curve (AUC) was statistically significant for all screens and were as follows: PHQ-9 = 0.70 (95% CI = 0.59-0.80), GAD-7 = 0.74 (95% CI = 0.63-0.84), and PCL-5 = 0.79 (95% CI = 0.66-0.91). The optimal accuracy cutoff scores based on sensitivity and specificity were: PHQ-9 ≥ 16, GAD-7 ≥ 9, the PCL-5 ≥ 42. CONCLUSIONS: In general, the candidate screeners performed acceptably in this population. However, the optimal cutoff scores were notably higher than existing guidelines for depression and PTSD, potentially due to the general elevations in negative affectivity among individuals initiating SUD treatment. Further validation of these cutoff values is warranted. PUBLIC HEALTH SIGNIFICANCE: This study provides modified screening cutoff scores for major depression, anxiety disorders, and post-traumatic stress disorder in addiction treatment settings.


Asunto(s)
Trastornos de Ansiedad , Depresión , Trastornos por Estrés Postraumático , Trastornos de Ansiedad/diagnóstico , Trastornos de Ansiedad/epidemiología , Depresión/diagnóstico , Humanos , Pacientes Internos , Tamizaje Masivo , Ontario/epidemiología , Psicometría , Sensibilidad y Especificidad , Trastornos por Estrés Postraumático/diagnóstico , Trastornos por Estrés Postraumático/epidemiología
2.
Exp Eye Res ; 87(2): 147-58, 2008 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-18617164

RESUMEN

The primary goal was to characterize the structural alterations that occur at the fiber cell interfaces in nuclei of fully opaque cataracts removed by extracapsular cataract surgery in India. The dark yellow to brunescent nuclei, ages 38-78 years, were probably representative of advanced age-related nuclear cataracts. Thick tissue slices were fixed, en bloc stained and embedded for transmission electron microscopy. Stained thin sections contained well-preserved membranes and junctions, although the complex cellular topology often made it necessary to tilt the grid extensively to visualize the membranes. Damage to the fiber cell membranes was noted in all regions of the nucleus. The most important damage occurred within undulating membrane junctions where the loss of membrane segments was common. These membrane breaks were not sites of fusion as membrane edges were detected and cytoplasm appeared to be in contact with extracellular space, which was enlarged in many regions. Dense deposits of protein-like material were frequently observed within the extracellular space and appeared to be similar to protein in the adjacent cytoplasm. The deposits were often 20-50 nm thick, variable in length and located on specific sites on plasma membranes and between clusters of cells or cell processes. In addition, low density regions were seen within the extracellular space, especially within highly undulating membranes where spaces about 100 nm in diameter were observed. The membrane damage was more extensive and extracellular spaces were larger than in aged transparent donor lenses. Because high and low density regions contribute equally to the fluctuations in refractive index, the changes in density due to the observed damage near membranes are likely to produce significant light scattering based on theoretical analysis. The dimensions of the fluctuations in the range 20-100 nm imply that the scattering is probably similar to that of small particles that would increase high-angle scattering visible in the slit lamp. Such damage to membranes would be expected to contribute to the total opacification of the nucleus as the cataract matures. The main sources of the fluctuations appear to be the degradation of membranes and adjacent cytoplasmic proteins, as well as the redistribution of proteins and fragments.


Asunto(s)
Catarata/patología , Núcleo del Cristalino/ultraestructura , Adulto , Anciano , Membrana Celular/ultraestructura , Citoplasma/ultraestructura , Espacio Extracelular , Humanos , Uniones Intercelulares/ultraestructura , Microscopía Electrónica , Persona de Mediana Edad , Modelos Biológicos , Dispersión de Radiación
3.
Exp Eye Res ; 86(2): 434-44, 2008 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-18191834

RESUMEN

Alterations in ultrastructural features of the lens fiber cells lead to scattering and opacity typical of cataracts. The organelle-free cytoplasm of the lens nuclear fiber cell is one such component that contains vital information about the packing and organization of crystallins critical to lens transparency. The current work has extended analysis of the cytoplasmic texture to transparent and advanced cataractous lenses from India and related the extent of texturing to the nuclear scattering observed using the Debye-Bueche theory for inhomogeneous materials. Advanced age-related nuclear cataracts (age-range 38-75 years) and transparent lenses (age-range 48-78 years) were obtained following extracapsular cataract removal or from the eye bank, at the L.V. Prasad Eye Institute. Lens nuclei were Vibratome-sectioned, fixed and prepared for transmission electron microscopy using established techniques. Electron micrographs of the unstained thin sections of the cytoplasm were acquired at 6500x and percent scattering for wavelengths 400-700 nm was calculated using the Debye-Bueche theory. Electron micrographs from comparable areas in an oxidative-damage sensitive (OXYS) rat model and normal rat lenses preserved from an earlier study were used, as they have extremely textured and smooth cytoplasms, respectively. The Debye-Bueche theoretical approach produces plots that vary smoothly with wavelength and are sensitive to spatial fluctuations in density. The central lens fiber cells from advanced cataractous lenses from India and the OXYS rat, representing opaque lens nuclei, produced the greatest texture and scattering. The transparent human lenses from India had a smoother texture and less predicted scattering, similar to early cataracts from previous studies. The normal rat lens had a homogeneous cytoplasm and little scattering. The data indicate that this method allowed easy comparison of small variations in cytoplasmic texture and robustly detected differences between transparent and advanced cataractous human lenses. This may relate directly to the proportion of opacification contributed by the packing of crystallins. The percent scattering calculated using this method may thus be used to generate a range of curves with which to compare and quantify the relative contribution of the packing of crystallins to the loss of transparency and scattering observed.


Asunto(s)
Catarata/patología , Citoplasma/ultraestructura , Núcleo del Cristalino/ultraestructura , Modelos Biológicos , Adulto , Anciano , Animales , Análisis de Fourier , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Microscopía Electrónica , Persona de Mediana Edad , Ratas , Dispersión de Radiación
4.
Mol Vis ; 7: 120-30, 2001 Jun 22.
Artículo en Inglés | MEDLINE | ID: mdl-11435998

RESUMEN

PURPOSE: To characterize within human age-related nuclear cataracts rare spherical objects covered by multiple membranes, termed multilamellar bodies (MLBs). METHODS: Adult human normal, transparent lenses were obtained from eye bank donors and age-related nuclear cataracts were obtained immediately after extracapsular extraction. Each sample was Vibratome sectioned fresh into 200 microm thick sections that were fixed and embedded for light or electron microscopy. Confocal images were recorded from sections stained with the lipid soluble dye, DiI. RESULTS: Light micrograph montages of the equatorial plane containing the fetal and embryonic nuclei were examined. Rare, but distinct, circular 1-3 microm diameter objects were observed consistently in the cataracts. These objects did not appear to be components of the complex intercellular interfaces. Serial sections indicated that the objects were spherical, or contained a spherical component. For about 20,000 fiber cell cross-sections in each lens, the frequency of MLBs was 10 times higher in cataracts than in the normal lens nuclei. Although extensive searching with the electron microscope was necessary, the size, circular profile and multiple layers of thin (5 nm) membranes easily identified the MLBs. Interiors of the MLBs displayed variable textures. Confocal images indicated that the coverings were enriched in lipid compared to the adjacent plasma membranes. The calculated density of the MLBs in the cataractous nuclei was about 3800/mm3, which represents a volume fraction of 0.00003. CONCLUSIONS: Because the MLBs are large compared to the wavelength of light, display interiors with variable staining textures and have lipid-rich coverings, they appear to be ideal candidates for large scattering particles that may contribute to the forward light scattering in nuclear cataracts.


Asunto(s)
Envejecimiento/patología , Catarata/patología , Cuerpos de Inclusión/patología , Núcleo del Cristalino/patología , Dispersión de Radiación , Anciano , Humanos , Cuerpos de Inclusión/ultraestructura , Núcleo del Cristalino/ultraestructura , Luz , Microscopía Confocal , Microscopía Fluorescente , Persona de Mediana Edad , Orgánulos/patología , Vacuolas/patología
5.
Exp Eye Res ; 72(3): 199-214, 2001 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-11180969

RESUMEN

This study was conducted to quantify structural change associated with human nuclear fiber compaction as a function of ageing and nuclear cataract formation. Normal donor lenses in three age ranges, young (15--25 years), middle-aged (36--46 years) and aged (59--81 years) were compared to each other and to age-related nuclear cataracts (55--81 years) surgically removed by extracapsular extraction. Several structural modifications which occurred as a manifestation of fiber compaction were noted. In the fetal nucleus (FN), the average anterior and posterior fiber angles decreased approximately 20% with age. Additionally, there was a reduction in the thickness of both the anterior and posterior segments of fetal fibers with age. On average, the anterior--posterior (A--P) axis in the embryonic nucleus (EN) decreased 33% with age. The average length of EN fibers decreased significantly (37%) as a function of age. This change in EN fiber length was accomplished by effecting compaction folds along fiber length. By comparison, in nuclear cataracts the anterior and posterior angles of FN fibers were about 12% smaller than comparably aged normal lenses. Similarly, the A--P axis and the length of EN fibers were 13% smaller than age-matched normals. Nuclear fiber compaction in early adulthood was significant and may contribute to the lens hardening and loss of accommodative ability symptomatic of presbyopia. 3D-CAD reconstructions of fiber compaction show how the reduction in the spacing of lateral interdigitations along fiber length causes an increase in the fiber membrane complexity along the A--P axis in relation to fiber cytoplasm as light passes through lenses. These results may explain, at least in part, how an increase in large particle scatter occurs as light is transmitted through fiber membranes, resulting in reduced lens optical quality as a function of age. By extrapolation, the significantly increased compaction of nuclear fibers in age-related nuclear cataracts may be a contributing factor for excessive scatter in nuclear opacification.


Asunto(s)
Envejecimiento/patología , Catarata/patología , Cristalino/diagnóstico por imagen , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Estudios de Casos y Controles , Humanos , Luz , Microscopía Electrónica de Rastreo , Persona de Mediana Edad , Presbiopía/patología , Dispersión de Radiación , Estadísticas no Paramétricas , Ultrasonografía
6.
Exp Eye Res ; 69(2): 163-74, 1999 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-10433853

RESUMEN

Variations in cytoplasmic texture of human normal and cataractous lenses were investigated with Fourier analysis. Fixed Vibratome sections of six normal transparent human lenses (age range 55-72 years) and six nuclear cataractous lenses (age range 66-89 years) were examined using transmission electron microscopy. Images were taken of the fiber cell cytoplasm and examined using linear optical density scans, Fourier transforms and autocorrelation analysis. The cytoplasm of normal human lenses was found to be smooth and homogeneous. Radially-averaged plots of Fourier transforms revealed a broad band of intensity over the range of 15-50 nm. Four of the six cataracts also had homogeneous cytoplasm without substantial density variations. Fourier transforms and radially-averaged plots were similar to those of the normal, although slightly lower in intensity for components/=200 nm. Autocorrelation analysis supported the data obtained by Fourier transforms. Radially-averaged plots of the autocorrelation resultant displays detected only small structural units in the normal and non-textured cataractous cytoplasm, whereas larger structural units were detected in the textured cataractous cytoplasm. The appearance of the textured cataractous cytoplasm suggests that redistribution or loss of protein may be the cause of density variations in these types of cataracts. Importantly, these results indicate that some nuclear cataracts do not contain spatial fluctuations in the cytoplasm large enough to cause significant light scattering. The data suggest that nuclear cataractogenesis is a multi-factorial process involving minor alterations in cellular structure.


Asunto(s)
Catarata/patología , Anciano , Anciano de 80 o más Años , Citoplasma/patología , Análisis de Fourier , Humanos , Microscopía Electrónica , Persona de Mediana Edad
7.
Mol Vis ; 3: 2, 1997 Feb 02.
Artículo en Inglés | MEDLINE | ID: mdl-9238091

RESUMEN

PURPOSE: A rapid means was sought to visualize and quantify the cross-sectional areas of fiber cells, the variations of cell area, and the regularity of packing in the equatorial plane of normal adult bovine and normal aged human lenses. METHODS: Vibratome sections of bovine and human lenses were fixed, embedded in LR White resin, and sectioned for light microscopic observation. Image analysis was performed to determine the cross-sectional areas of fiber cells in selected nuclear regions. RESULTS: Examination of bovine lenses revealed a pattern of cell size and shape in each region that was similar to that recently reported for normal human lenses (1). In the equatorial plane of bovine lenses, average cross-sectional areas were 20 +/- 6 micron2 in the adult nucleus, 43 +/- 19 micron2 in the fetal nucleus, and 63 +/- 61 micron2 in the embryonic nucleus. Light microscopy of human lenses was consistent with our previous electron microscopic observations. Moreover, in both bovine and human lenses, the distribution of cell sizes and the number of cell layers was readily available for each region. Overviews of the equatorial plane demonstrated a gradual improvement in the regular packing of radial cell columns proceeding from the relatively disordered embryonic and fetal nuclei through the well-ordered adult nucleus to the highly regular cortical region. CONCLUSIONS: Light microscopy revealed the highly irregular packing and large average size of cells in the embryonic nucleus and the gradual reduction in size and progressive improvements in regularity of packing in the outer layers. The methods used here have the advantage of rapidly giving a continuous view of the fiber cell structure and arrangement which is not available using electron microscopy.


Asunto(s)
Bovinos/anatomía & histología , Cristalino/citología , Anciano , Animales , Histocitoquímica , Humanos , Procesamiento de Imagen Asistido por Computador , Persona de Mediana Edad
8.
Invest Ophthalmol Vis Sci ; 37(7): 1396-410, 1996 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-8641842

RESUMEN

PURPOSE: To provide a quantitative, morphologic description of differentiated lens fiber cells in all regions of aged normal human lenses. METHODS: Transparent normal human lenses (age range, 44 to 71 years) were examined with correlative transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Vibratome sections allowed examination of internal structures, whereas dissected whole lenses revealed surface characteristics. Additionally, image analysis was used to measure cross-sectional areas of fiber cells. RESULTS: Approximate regional dimensions (percentage of diameter and thickness, respectively) were determined for whole lenses: cortex 16%, 17%; adult nucleus 24%, 21%; juvenile nucleus 12%, 9%; fetal nucleus 45%, 49%; and embryonic nucleus 3%, 4%. Cortical cells were irregularly hexagonal, and the average cross-sectional area measured 24 +/- 9 microns2. Adult nuclear cells were flattened with intricate membranous interdigitations and an area of 7 +/- 2 microns2. Juvenile nuclear cells had an area of 14 +/- 5 microns2. Fetal nuclear cells were rounded with an area of 35 +/- 22 microns2. Embryonic nuclear cells also were rounded and had a variable area of 80 +/- 68 microns2. Fiber cell cytoplasm in all lens regions appeared smooth in texture and homogeneous in staining density. CONCLUSIONS: Both TEM and SEM are necessary to obtain a complete description of fiber cells. Cross-sections of fibers give new insights into the lamellar organization of the lens, indicating that each region has characteristic cell shapes and sizes. Furthermore, average dimensions were used to demonstrate that the number of cells and approximate growth rates vary significantly between adjacent regions.


Asunto(s)
Cristalino/ultraestructura , Adulto , Anciano , Envejecimiento/fisiología , Diferenciación Celular , Humanos , Procesamiento de Imagen Asistido por Computador , Corteza del Cristalino/ultraestructura , Núcleo del Cristalino/ultraestructura , Cristalino/citología , Cristalino/fisiología , Microscopía Electrónica de Rastreo , Persona de Mediana Edad
9.
Curr Eye Res ; 15(5): 533-42, 1996 May.
Artículo en Inglés | MEDLINE | ID: mdl-8670754

RESUMEN

PURPOSE: The goal of this study was to compare the ultrastructure of the oldest cells in opaque and transparent human lenses. METHODS: Age-related nuclear cataracts, late-onset diabetic nuclear cataracts and normal aged lenses were examined by transmission electron microscopy. Cross-sectional profiles of fiber cells in the embryonic, fetal and juvenile nuclear regions were obtained to facilitate direct comparisons between lens regions and between sample groups. Image analysis was performed to determine cross-sectional areas of fiber cells in each region. RESULTS: The average cross-sectional area increased approximately sixfold from the outer to the inner nuclear regions in all lenses measured. In each nuclear region, fiber cells displayed a characteristic size, shape, arrangement and type of interdigitations which were consistently seen in all the lenses examined. Some lenses had more complex interdigitations than others. Gap junctions were identified as pentalamellar structures having 16 nm width and appeared identical throughout the nuclei of both normal and cataractous lenses. The cytoplasm of all lenses was smooth and free of large density variations. However, the cytoplasm of some cataractous lenses appeared more granular in texture than noncataractous lenses. Cellular degeneration, debris or large cellular defects were not seen in the cores of cataractous lens nuclei. CONCLUSIONS: These results indicate that only minor ultrastructural differences exist between the oldest fiber cells in normal and cataractous lenses, and that the presence of extensive cellular damage and disruptions is not necessary for the generation of nuclear opacities in aged lenses. Our observations suggest that light scattering sufficient for vision impairment may involve structural alterations much smaller than previously proposed.


Asunto(s)
Catarata/patología , Núcleo del Cristalino/ultraestructura , Anciano , Anciano de 80 o más Años , Envejecimiento/patología , Catarata/etiología , Citoplasma/patología , Citoplasma/ultraestructura , Diabetes Mellitus Tipo 2/complicaciones , Uniones Comunicantes/patología , Uniones Comunicantes/ultraestructura , Humanos , Núcleo del Cristalino/citología , Núcleo del Cristalino/patología , Microscopía Electrónica
10.
Exp Eye Res ; 62(3): 237-51, 1996 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-8690033

RESUMEN

The distribution and type of fiber cell damage was evaluated in human age-related nuclear cataracts and in aged normal (non-cataractous) lenses. Ten age-related nuclear cataracts (53 to 89 years old) and four normal lenses (59 to 67 years old) were examined by electron microscopy of fixed Vibratome sections. Images from the adult, juvenile, fetal and embryonic nuclear regions were compared. Each cataractous lens contained a central region of increased light scattering which involved the embryonic and fetal regions with progressively less involvement in the juvenile and adult nuclear regions. Some damaged fiber cells were observed in all specimens, although damage was minor and infrequent in the normal lenses. Degeneration of single or groups of fiber cells was noted in all the adult nuclei of the cataractous lenses, becoming less frequent in the juvenile nuclei. The types of damage included localized voids, multilamellar membrane aggregates, globular bodies, enlarged cells and regions of highly convoluted membranes. The fetal and embryonic nuclei of the cataractous lenses exhibited rare and minor morphological defects, and were virtually identical to the equivalent regions of the normal aged lenses. Examination of cell interfaces in opaque regions of cataractous lenses revealed that the oldest fiber cells sustained apparent membrane loss. Extracellular spaces in the embryonic, fetal and juvenile regions of the cataractous lenses often contained dense deposits, presumably cytoplasmic material lost from adjacent fibers. The results indicate that the region of greatest nuclear opacity, located in the lens center, does not contain any significant cellular damage. This suggests that older fiber cells respond differently to pathological and senescent changes than younger cells made after fetal development. The observed loss of membranes and cytoplasmic material from the oldest fiber cells may be a contributory mechanism in the formation of age-related human nuclear cataracts.


Asunto(s)
Catarata/patología , Cristalino/ultraestructura , Anciano , Anciano de 80 o más Años , Envejecimiento/patología , Humanos , Microscopía Electrónica , Persona de Mediana Edad
11.
Environ Pollut ; 93(1): 17-25, 1996.
Artículo en Inglés | MEDLINE | ID: mdl-15091365

RESUMEN

Adult sand gobies were exposed to 0.1% sewage sludge for 19 weeks prior to the end of spawning. Exposure to sewage sludge had a significant effect on male mortality rates but no significant effects on the gonadosomatic index of males or females. There were no major effects of sludge exposure on testes androgen content or on testes release of androgens after in vitro gonadotrophin stimulation. Fecundity and the number of larvae produced were not significantly affected by the sludge exposure. There was a tendency for eggs and larvae from sludge-exposed females to have a higher mortality rate. At a population level, however, there was a major reduction in the number of eggs and larvae produced in the sludge-exposed population which reflected a failure of some females to spawn. Of the larvae produced, 60-70% from sludge-exposed parents were lighter and had a larger yolk-sac volume compared to larvae from non-exposed parents which may have indicated impaired yolk utilisation.

14.
Exp Eye Res ; 57(4): 469-86, 1993 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-8282033

RESUMEN

The ultrastructure of human diabetic lens nuclei is described for the first time. Two cataractous lenses from late-onset diabetics were examined using transmission electron microscopy to determine the type and distribution of cellular disruptions. The diabetic lens nuclei were compared to a transparent nucleus from a normal human lens. Cellular damage to the exterior region of the diabetic lens nuclei was extensive, especially at the cortical-nuclear interface. Areas of lens fiber condensation as well as areas of cytoplasmic loss were observed in the outer nucleus. Morphological defects commonly seen in this region included: multilamellar membrane aggregates, voids where cytoplasmic material was lost, deposits in the extracellular spaces, density variations between adjacent fiber cells, and heterogeneously staining globules. The opaque central regions of the nuclei displayed relatively little cell damage, but fiber cells were very irregular in shape and packing. The ultrastructure of inner nuclear fiber cells was comparable to that seen in the normal lens and in age-related nuclear cataracts in non-diabetics. It appears that the effect of hyperglycemia on lens fiber cells is dependent on their age and stage of differentiation.


Asunto(s)
Catarata/patología , Diabetes Mellitus Tipo 2/patología , Núcleo del Cristalino/ultraestructura , Anciano , Membrana Celular/ultraestructura , Femenino , Humanos , Microscopía Electrónica , Persona de Mediana Edad
16.
Invest Ophthalmol Vis Sci ; 34(7): 2174-85, 1993 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-8389342

RESUMEN

PURPOSE: The goal of this ultrastructural study was to examine fiber cell shape and intercellular junctions during the early stages of fiber cell breakdown and edema in diabetic rabbit lenses. METHODS: Lens abnormalities were recorded with a slit lamp. Between 6-10 mo after drug treatment, diabetic lenses and untreated control lenses were freshly enucleated and sectioned with a vibrating knife microtome. The thick tissue sections were chemically fixed and processed for thin-section electron microscopy. RESULTS: Alloxan-induced diabetes in albino rabbits produced clinically apparent cataracts as soon as 1 mo after the animals became hyperglycemic. The cataracts displayed cortical fluid-filled vacuoles in the equatorial region and at the cortex-nucleus interface, white specks scattered throughout the cortex, and posterior subcapsular cataracts. Fiber cells just deeper than the large cortical vacuoles had oval or spindle-shaped cross sections. Multilamellar inclusions, not reported previously for diabetic lenses, were observed at or near the fiber cell interfaces and were composed of concentric or spiral rings of plasma membrane-bound cytoplasmic processes. Undulating membranes were present throughout most of the multilamellar inclusions. Transparent lenses from untreated controls did not have such multilamellar bodies or extensive membrane undulations in cells at the same distance from the lens surface. CONCLUSIONS: Fiber cells respond to the diabetic insult differently depending on their stage of differentiation and age. The observed changes are consistent with the hypothesis that hyperglycemia accelerates the formation of age-related changes in fiber cells.


Asunto(s)
Catarata/patología , Diabetes Mellitus Experimental/patología , Cuerpos de Inclusión/ultraestructura , Cristalino/ultraestructura , Aloxano , Animales , Membrana Celular/ultraestructura , Uniones Intercelulares/ultraestructura , Corteza del Cristalino/ultraestructura , Núcleo del Cristalino/ultraestructura , Conejos , Vacuolas/ultraestructura
17.
Aust Orthod J ; 12(3): 151-2, 1992 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-1300992

RESUMEN

A range of orthodontic instruments was artificially inoculated with a mixed culture of representatives of the oral microflora and a marker bacterium and subjected to dry heat sterilization using a glass bead sterilizer. The shortest time which would guarantee total sterilization of the functional parts of the instruments was thirty seconds.


Asunto(s)
Instrumentos Dentales , Esterilización/métodos , Ortodoncia/instrumentación
18.
Invest Ophthalmol Vis Sci ; 33(11): 3209-27, 1992 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-1399426

RESUMEN

Age-related or senile human nuclear cataracts were examined using electron microscopy of thin sections prepared from thick vibrating-knife microtome sections of nuclei extracted by extracapsular surgery. The use of extended aldehyde-tannic acid fixation of 80-120-microns thick vibrating-knife microtome sections overcame the difficult problem of preserving the hardened nuclear core of aged lenses. Comparisons were made between a typical nuclear cataract, containing a central opacity and a transparent rim, and a more advanced, or mature, completely opaque nuclear cataract. The typical nuclear cataract contained no obvious cell disruption, cellular debris, or objects that readily could explain the central opacity. The fiber cells had intact uniformly stained cytoplasms with well-defined plasma membrane borders and gap junctions. The transparent rim and the nuclear core appeared similar, except that fiber cells in the nucleus were more condensed with more elaborate intercellular interdigitations. The mature cataract showed various types of cell disruption in the perimeter but not in the core of the nucleus. These disruptions were globules, vacuoles, multilamellar membranes, and clusters of highly undulating membranes. Because these potential scattering centers were not found in the nuclear core, they probably were not the sole cause of the observed opacity. Other potential scattering centers found throughout the mature cataract nucleus included variations in staining density between adjacent cells, enlarged extracellular spaces between undulating membrane pairs, and protein-like deposits in the extracellular space. Similar features, although less pronounced, were present in the typical nuclear cataract. It was concluded that massive cell disruption is not essential to the formation of a central nuclear opacity. Subtle structural changes, especially small fluctuations in protein density between adjacent cells and alterations of the membranes and the extracellular space, probably contribute significantly to the central opacities in human nuclear cataracts.


Asunto(s)
Catarata/patología , Núcleo del Cristalino/ultraestructura , Anciano , Extracción de Catarata , Humanos , Uniones Intercelulares/ultraestructura , Cápsula del Cristalino/ultraestructura , Microscopía Electrónica , Persona de Mediana Edad , Fijación del Tejido
19.
J Bacteriol ; 174(20): 6608-16, 1992 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-1400212

RESUMEN

Overproduction of the sn-glycerol-3-phosphate acyltransferase in Escherichia coli leads to incorporation of this integral membrane protein into ordered tubular arrays within the cell. Freeze-fracture-etch shadowing was performed on suspensions of partially purified tubules and whole bacteria. This procedure revealed the presence of ridges and grooves defining a set of long-pitch left-handed helical ridges. The long-pitch helices represented chains of acyltransferase dimers. Tubules observed within the cell were often closely packed, with an apparent alignment of grooves and ridges in adjacent tubules. Fracture planes passing through the tubules indicated the presence of a bilayer structure, with some portion of the enzyme being associated with the membrane. The major portion of the enzyme extended from the hydrophilic surface, forming a large globular structure that, in favorable views, displayed a central cavity facing the cytoplasm. Computer analysis of shadowed tubules revealed that the left-handed helices were six stranded, with a pitch of 1,050 A (105.0 nm) and a spacing of 75 A (7.5 nm) between acyltransferase dimers along the chains. Analysis of the predicted secondary structure failed to reveal obvious transmembrane segments, suggesting that very little of the protein was inserted into the bilayer.


Asunto(s)
Escherichia coli/enzimología , Glicerol-3-Fosfato O-Aciltransferasa/ultraestructura , Citoplasma/enzimología , Citoplasma/ultraestructura , Escherichia coli/ultraestructura , Grabado por Congelación , Glicerol-3-Fosfato O-Aciltransferasa/química , Microscopía Electrónica de Rastreo
20.
Artículo en Inglés | MEDLINE | ID: mdl-1677844

RESUMEN

1. Dab, Limanda limanda, exposed to nominal concentrations of 0 (control), 0.0032% (low) and 0.032% (high) sewage sludge in seawater for 12 weeks, were assessed for their immunological competence. 2. No effect upon total blood leucocyte and erythrocyte numbers was found, although significantly fewer thrombocytes were seen in the high-exposure group. 3. A decreased serum protein level was found in the high exposure group, but lysozyme and immunoglobulin levels showed non-significant differences between the groups. 4. Melano-macrophage centres were also affected in the high-exposure dab, which had increased numbers in the spleen and kidney. No effect upon spleen weights or oxygen free radical production by splenocytes was noted. However, oxygen free radical production by kidney leucocytes was inhibited in the low-exposure dab.


Asunto(s)
Peces/inmunología , Inmunocompetencia/efectos de los fármacos , Aguas del Alcantarillado/efectos adversos , Contaminantes Químicos del Agua/toxicidad , Animales , Riñón/efectos de los fármacos , Riñón/patología , Fagocitos/efectos de los fármacos , Bazo/efectos de los fármacos , Bazo/patología
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