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K Oates

Publications and source records attributed to K Oates.

At least 37 records · Page 2Linked to original sources
PubMed1987

Quantitative X-ray microanalysis of bulk hydrated specimens: a method using gelatine standards.

A method of preparing and using gelatine blocks as standards for quantitative X-ray microanalysis of bulk hydrated tissue is described. Each series of standards had several constant and one variable element. The average deviations in the X-ray counts of the constant elements from the series means were used to correct the recorded count of the variable element in each block. This led to an improved linear relationship between X-ray counts and concentration. The elements tested, sodium, phosphorus, and potassium, were chosen as representatives of different parts of the X-ray spectrum. Sodium cannot be measured reliably below 50 mmol kg-1 wet weight, although phosphorus and potassium can be detected at concentrations of 5 mmol kg-1 wet weight. It is argued that this sensitivity of analysis is sufficient for studying electrolyte changes in certain pathological processes.

Electron Probe Microanalysis↗
PubMed1987

Personality development following sexual abuse.

Thirty-seven girls and twelve boys who had been sexually abused at an average of 2.6 years previously were traced and reviewed. The nonoffending parents participated in a structured interview and the children were assessed using the Piers-Harris Self-Concept Scale and the Achenbach Child Behavior Checklist. Each child was matched with a child not known to have been sexually abused and these control children underwent a similar psychological assessment. Interviews with the nonoffending parents found that 76% of the children were thought to be less confident than before, 30% had fewer friends, and 20% were more aggressive. Increased sexual awareness was noted in 24%. School teachers reported that 28% still had behavior problems, 17% had repeated a year at school, and a further 17% had deteriorated in their school work. The sexually abused girls had significantly lower self-esteem than the control girls. There was no difference in self-esteem between the control and the sexually abused boys. There was a higher incidence of stranger assault in the boys compared with the girls. The Child Behavior Checklist completed by the parents, the Teacher Report Form, and the Youth Self-Report of the Child Behavior Checklist showed that a highly significant proportion of sexually abused children fell into the clinical range. Sexual abuse appears to have long-term adverse consequences for many of the victims. This may have implications for their ability to relate to others, for the adult friendships they will make, and eventually for the way they will relate to their own children.

Adolescent↗
PubMed1987

Oxygen tensions and oxyhemoglobin saturations in the assessment of pulmonary gas exchange.

We studied the theoretical basis for continuous monitoring of pulmonary gas exchange using arterial and mixed venous oximetry by examining the mathematical relationships between the calculated venous admixture (Qsp/Qt) and the ventilation-perfusion index, which is derived from oxyhemoglobin saturations. We compared this relationship with that between Qsp/Qt and its commonly used estimates: inspired oxygen concentration to arterial blood oxygen tension ratio, arterial to alveolar oxygen tension ratio, and alveolar-arterial oxygen tension difference. The relationship between Qsp/Qt and the oxygen tension-based indices is nonlinear and substantially influenced by changes in inspired oxygen concentration and arteriovenous oxygen content difference. Therefore, it is inaccurate within the clinically acceptable range of arterial blood oxygenation. In contrast, calculation of ventilation-perfusion index from arterial and mixed venous blood oxyhemoglobin saturations provides a linear estimate of Qsp/Qt that is minimally affected by alterations in inspired oxygen concentration or oxygen uptake and, therefore, will allow accurate continuous assessment of pulmonary gas exchange.

Humans↗
PubMed1986

Electron-microscopic and electrophoretic studies of bovine femoral-head cartilage proteoglycan fractions.

Proteoglycans (A1D1) extracted from bovine femoral-head cartilage were examined by electron microscopy using benzyldimethylammonium chloride as a spreading agent. The preparation contained a mixture of particles, some with a 'beaded' structure and a contiguous filamentous 'tail' at one end and others which appeared as round 'blobs', some of which also had filamentous tails. Previous electron-microscopic studies of proteoglycan monomers have indicated that their length distributions were apparently unimodal, a finding that contrasted with agarose/polyacrylamide-gel-electrophoresis results, which generally indicated two bands. In the present study proteoglycans isolated from the slowly migrating electrophoretic band were shown to be predominantly the larger molecules of beaded appearance, whereas the rapidly migrating proteoglycans were predominantly molecules with the 'blob-like' appearance. Gel-filtration, isopycnic-density-gradient-centrifugation and rate-zonal-centrifugation techniques were evaluated as means of proteoglycan fractionation by electron microscopy and agarose-gel electrophoresis. Rate-zonal centrifugation in mixed-salt gradients of caesium chloride/4 M-guanidinium chloride yielded the most effective fractionation.

Animals↗
PubMed1986

Electron microscopy of cervical, gastric and bronchial mucus glycoproteins.

Mucus glycoproteins (mucins) were obtained from human cervical and pig gastric mucus as well as from chronic-bronchitic sputum after low-shear extraction. The mucus gel was solubilized in guanidinium chloride supplemented with proteinase inhibitors, and the macromolecules were purified by using isopycnic density-gradient centrifugation. The macromolecules were spread in monolayers of benzyldimethylalkyl-ammonium chloride and studied with electron microscopy after staining with uranyl acetate and/or shadowing with platinum/carbon. The mucins appeared as flexible linear threads with lengths varying from approx. 200 nm to about 400 nm. No regularly branched or star-shaped structures were observed. The macromolecular architecture of cervical, respiratory and gastric mucins is thus similar.

Animals↗
PubMed1986

Scanning electron microscopy of adenomatoid tumours.

Four adenomatoid tumours of the epididymis were embedded in paraffin wax, sectioned and the sectioned surfaces examined by scanning electron microscopy using the secondary electron mode. The solid faces of the sectioned neoplasms were damaged by the preparative technique but the depressed luminal surfaces of the tubules were well preserved and yielded useful information. Large areas of luminal surface were examined and the presence and distribution of microvilli were noted. In addition, there was a more complex cell surface pattern of intersecting cord-like elevations. Desquamating cells were seen within the tubules and the cytoplasmic bridges noted by light microscopy were shown to be thin cytoplasmic partitions. These findings are consistent with the mesothelial theory of histogenesis. Scanning electron microscopy can provide useful information about the internal structure of neoplasms even with simple preparative techniques.

Aged↗
PubMed1985

Low temperature and conventional scanning electron microscopy of human urothelium.

The appearance of fixed dehydrated non-neoplastic human urothelium viewed by conventional scanning electron microscopy (CSEM) is different from that of frozen hydrated human urothelium viewed by low temperature scanning electron microscopy (LTSEM). In the fixed dehydrated material the surface is formed by well defined, polygonal, domed superficial urothelial cells which have prominent surface microridges. In places intermediate urothelial cells are visible and they have surface microvilli. In the frozen hydrated material viewed by LTSEM most of the surface is smooth. This is formed in part by a glutaraldehyde soluble extracellular secretion which may be a mucin barrier to bacteria. We believe that the rest of the smooth surface is formed by superficial urothelial cells which are not well defined and which lack microridges. There are islands of rounded cells lacking microvilli which are probably intermediate urothelial cells as they correspond in appearance with the intermediate urothelial cells seen in freeze fractured material. It seems likely that fixation and dehydration will cause some change in surface configuration and in theory the frozen hydrated material should more closely resemble the natural state. We believe that LTSEM will be of value in investigating normal and diseased urothelium.

Cytological Techniques↗
PubMed1985

Low temperature and conventional scanning electron microscopic observations of dog femoral condylar cartilage surface after anterior cruciate ligament division.

The left stifle joints of 16 beagle dogs were subjected to surgical division of the anterior cruciate ligament (ACL). The femoral condyles showed surface alterations and damage after 14 days when examined by low temperature (LTSEM) and conventional scanning electron microscopy (SEM). The first change was an increase in the fibrous texture of the articular cartilage surface. Folds and surface roughening were later recognised. After 112 days deformation and disruption gave way to cracking or fracture of the surface layers. Superficial damage was focal in distribution and accompanied by a decrease in the frequency of tertiary elevations. The affected areas of cartilage increased in frequency and size with time and surgery. The observations obtained from LTSEM, in which the tissue remains fully hydrated during examination, may be caused by alterations in water content and a loss of proteoglycan at the surface, together with changes in cell shape and size. Surface cracks may be the en face appearance of histological fibrillation.

Animals↗
PubMed1984

Chitin helicoids accompany protein helicoids in the periostracum of a whelk, Buccinum.

The periostracum of the marine gastropod Buccinum has a helicoidal arrangement of its principal constituent which is a fibrous protein (Hunt and Oates, 1978). Chitin, chemically and physically identified, is present at a concentration of about 6% of the dry weight and can be seen in dispersates of whole periostracum as long fibrils and ribbons between 3 and 14 nm diameter. Deproteinization with hot alkali removes all protein leaving a chitinous 'ghost' of the periostracum. Dispersates, examined negatively stained, show only chitin fibrils and ribbons while sectioned material demonstrates a tenuous, part orthogonal, part helicoidal, architecture based on the chitin residue. The relative roles of the protein and polysaccharide components is speculated upon and comparisons with arthropod cuticle drawn.

Amino Acids↗
PubMed1984

Low temperature backscattered electron imaging in the study of human tissues.

A scanning electron microscopic technique for the examination of bulk, fresh, hydrated human tissue is described. Samples of fresh tissue are frozen in liquid nitrogen against a mirror-finished copper block and planed in a cryoultramicrotome before transfer to a low temperature scanning electron microscope. After sublimation of water from the specimen surface, the tissue is examined in secondary electron and backscattered electron modes. Adjacent pieces of tissue, and those retrieved after backscattered electron observation, can be readily prepared for and examined by light and by conventional transmission electron microscopy. The method has been tested with multiple blocks taken from 6 cases of human breast carcinoma. In the backscattered electron mode, the infiltrating columns of neoplastic cells can be distinguished from mammary adipose and fibrous tissue. Within a carcinoma, the collagenous stroma, carcinoma cells, and perivascular and perineural infiltrates can be identified. These features have been contrasted with those obtained by light microscopy, by low temperature scanning, and by transmission electron microscopy. This use of backscattered electron imaging for the investigation of unfixed hydrated tissue offers the possibility that the technique could be of considerable value in the microscopy of very small samples in which, because of a need for subsequent biochemical, histochemical, and immunologic investigation, fixation and dehydration are to be avoided.

Adenocarcinoma, Scirrhous↗
PubMed1984

Demonstration by X-ray microprobe analysis of relationship between chondrocytes and tertiary surface structure of hyaline articular cartilage.

Blocks of hyaline cartilage from the femoral condyles of five young adult beagles dogs were quench-frozen in nitrogen slush at 63 K. The free cartilage surfaces of blocks from three animals were examined in the secondary electron mode; the remaining specimens were cut by cryoultramicrotone (approximately 188 K) tangential to the surface to expose midzone cartilage which was examined in the backscattered electron mode. A random array of gently convex prominences was apparent at the free cartilage surfaces. When X-ray emissions were recorded from tissue immediately below these elevations, the spectra proved to be similar to those derived from midzone chondrocytes. These spectra revealed high count rates for the X-rays characteristic of P and K. By contrast, in areas of free surface remote from these prominences, and in midzone intercellular matrix, larger count rates for the X-rays characteristic of Na, S. Cl and Ca were detected. The evidence supports the hypothesis that the elevations seen on the non-loaded articular cartilage of disarticulated mammalian synovial joints are the surface representations of superficial chondrocytes.

Animals↗
PubMed1983

An investigation by transmission electron microscopy of freeze replicas of dog articular cartilage surfaces: the fibre-rich surface structure.

Femoral condylar cartilage blocks from the disarticulated stifle joints of five inbred beagle dogs were rapidly frozen. Single stage platinum and carbon replicas were prepared at 78 K from the unfixed, hydrated frozen material. Transmission electron microscopic investigations of the replicas were then made. Two different forms of fine cartilage surface structure were suggested by the low temperature replicas. The first, amorphous and with few fibres, was thought to represent the normal, superficial lamina obscurans. The second displayed many delicate parallel arrays of collagen fibrils with a periodic structure of 68-71 nm. Between these arrays were gently convex smooth-surfaced elevations, 150-500 nm in diameter, and therefore two orders of magnitude smaller than the tertiary surface undulations previously identified by light microscopy and by scanning electron microscopy. It is suggested that the 150-500 nm elevations seen at the replicated surface may be expanded proteoglycans, restrained laterally and deeply, less restrained superficially because of the loss, during preparation, of the lamina obscurans. Other hemispherical, replicated surface deposits 400-1700 nm in diameter are believed to be lipid.

Animals↗
PubMed1981

Low temperature scanning electron microscopy of dog and guinea-pig hyaline articular cartilage.

Fifty seven blocks of cartilage excised from the femoral condyles of 20 beagle dogs, and whole lower ends of 5 guinea-pig femora, were examined at -195 degrees (78 K), by scanning electron microscopy. The unfixed tissue, taken into slushy nitrogen at -210 degrees (63 K), was not exposed to atmospheric air after quenching and remained fully hydrated throughout long periods of observation. Images susceptible to analysis were obtained from washed and from unwashed cartilage surfaces. Preliminary coating with gold or with aluminium, known to be possible without exposing cold cartilage surfaces to changes in temperature likely to cause water loss by sublimation, was valuable in minimising charging and in facilitating the recording of electron images at higher magnifications. Although examination was possible without coating, the resultant images were of low resolution. Microscopy revealed a pattern of secondary surface irregularities of tertiary elevations closely resembling those seen by the conventional scanning electron microscopy of fixed, dehydrated hyaline cartilage. However, the pattern of tertiary surface structures was predominantly that of elevations, not of hollows. Quaternary surface ridges were common on the surfaces of excised dog cartilage blocks and were not seen on the surfaces of guinea-pig cartilage which remained on the femoral condyles.

Animals↗