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S Siew

Publications and source records attributed to S Siew.

17 recordsLinked to original sources
PubMed1988

Angiosarcoma of the adrenal gland.

We report the first case of primary angiosarcoma of the adrenal gland, to our knowledge. A 54-year-old man presented with chronic left upper quadrant abdominal pain, and a left adrenal mass was subsequently found on computed tomography of the abdomen. The tumor was surgically removed and a diagnosis of adrenal angiosarcoma, supported by findings of immunoperoxidase and ultrastructural studies, was made. Seven months later, recurrent tumor resulted in an en bloc resection of lateral gastric wall, tail of pancreas, left kidney, and spleen. One year after the initial surgery, the patient was free of tumor. Angiosarcoma should be added to the list of possible primary adrenal gland malignancies.

Adrenal Gland Neoplasms↗
PubMed1987

Abrogation of adriamycin-induced cardiotoxicity by selenium in rabbits.

Adriamycin-induced cardiomyopathy in rabbits was produced by intravenous injections of the drug with a short therapeutic schedule (3 mg/kg body wt administered as four intermittent doses). Animals receiving selenium supplementation of Adriamycin showed preservation of the normal pattern of the heart histologic picture. The protective effect of selenium was accompanied by increased selenium levels in the plasma and the heart muscle. An eventual interaction between the antitumor effect of Adriamycin and the protective effect of selenium was ruled out by in vitro experiments using the L1210 cell line. Selenium did not abrogate the antiproliferative effect of Adriamycin when the cells were treated simultaneously with both agents. The results from this study indicate that Adriamycin-induced cardiotoxicity could be prevented by selenium if the animals were pretreated with selenium, rather than simultaneous administration of both agents. The mechanism of this effect is not entirely understood.

Animals↗
PubMed1986

Ultrastructural investigation of the testicular defect in rats carrying MHC-linked genes affecting development (grc).

The morphologic features of the testicular defect in the rat caused by the genes of the growth and reproduction complex (grc), which are linked to the major histocompatibility complex (MHC), were examined by transmission and scanning electron microscopy in animals homozygous for grc (grc/grc), heterozygous for grc (grc/+), and normal (+/+). The testes of the grc homozygotes were small, and their tubular epithelium showed a loss of the normal organization. There were no sperm because the spermatogonia developed only to the pachytene stage of the primary spermatocyte; there was cellular degeneration and necrosis; and the basal lamina showed reduplication and invagination into the tubule. The number of the Sertoli cells was increased, their nuclei were displaced into the adluminal layers of the tubular epithelium, and their cytoplasm extended into the lumens. There was an increase in interstitial fibrous tissue, and the blood vessels deep in the parenchyma had thickened walls. In the heterozygotes, there was some architectural disorganization of the tubular epithelium and a greater number of tubules with a low concentration of sperm tails. Some of the intermediate spermatogonia were not attached to the basal lamina, and there was an increase in developmental abnormalities and abnormal sperm. The number of Sertoli cells was increased, and their nuclei extended into the second and third layers of the tubular epithelium. The homozygous wild type animals showed normal testicular development and normal spermatogenesis. This is the first description of a developmental defect in the rat that is under the control of a well-defined genetic system. It also is the first evidence for the morphologic expression of a heterozygous recessive gene in an animal that is phenotypically normal.

Animals↗
PubMed1985

Scanning electron microscopy of the human myocardium.

Owing to the impossibility of fixation, in the human being, by means of perfusion in vivo and the rare availability of fresh comparatively intact hearts resected at transplantation, the possibility was explored of using post-mortem material in instances where the autopsies were performed within 2 hours of demise of the patients. Four cases were examined: 2 normal adult hearts and 2 hearts of hypertensive patients in the stage of decompensation. The hearts were fixed by means of perfusion with 2.5% glutaraldehyde in phosphate buffer, pH 7.4. Contiguous blocks were taken for light microscopy (LM) and scanning electron microscopy (SEM) from the left ventricular free wall of all 4 cases and of the impulse conducting system of the heart in the 2 normal hearts. The SEM material was processed by the osmium-thiocarbohydrazide-osmium method (O-T-O). There was good correlation between the LM and SEM findings. The left ventricular blocks were sectioned in the transverse axis and SEM showed a step-wise transection of the myofibrils. Z and M bands, mitochondria and myofilaments were identified a ultrastructural magnifications. The difference in vascularity between normal and hypertensive myocardium and the presence of para-arterial fibrosis in the latter were demonstrated by SEM. The SEM study of the impulse conducting system of the heart included the sinoatrial (SA) and atrioventricular (AV) nodes and the penetrating portion of the atrioventricular (AV) bundle of His. Characteristic pacemaker or "P" cells were identified in the nodes.

Adult↗
PubMed1983

Major histocompatibility complex (MHC)-linked genes affecting development.

Genes affecting growth and development which are linked to the major histocompatibility complex have been found in the mouse (t-complex) and in the rat (growth and reproduction complex, grc), and there is some evidence that they also exist in humans. The genes of the t-complex have different effects depending upon the specific combinations involved: skeletal and fertility abnormalities, complete or partial embryonic mortality, high transmission ratios (segregation distortion) in males, high level of linkage disequilibrium with H-2, and suppression of recombination over the adjacent portion of the chromosome. The grc in the homozygous state causes small body size, sterility in the male and reduced fertility in the female, partial embryonic mortality, and a high level of linkage disequilibrium with RT1. It also interacts epistatically with the heterozygous Tal (tail anomaly lethal) gene to cause complete embryonic death. Mice carrying t-haplotypes and rats carrying the grc have an antigen in the male germ cells which cross-reacts very strongly (t-antigen). Suggestive evidence for such genes in humans comes from (1) studies on the relationship between skeletal defects and HLA haplotypes; (2) the association of specific HLA and complement haplotypes with a high transmission ratio in males, linkage disequilibrium among certain HLA and complement specificities and suppression of recombination in some MHC haplotypes; and (3) the lack of homozygotes in an isolated inbreeding population of desert nomads (Kel Kummer Tuaregs). In addition, immunogenetic studies on couples having chronic spontaneous abortions suggest that there is an unusually high incidence of homozygosity for the HLA-D/DR and HLA-A loci in these couples, and this finding is consistent with the presence of linked loci which behave like t or grc.

Animals↗
PubMed1983

Scanning electron microscopy of the human hippocampus.

The human hippocampus was studied by means of scanning electron microscopy (SEM) because further investigation of its neuroanatomy has been stimulated by increasing evidence of its functional significance. Human brains were removed within 2 hours of demise and were fixed in 10% buffered formalin for several weeks. After routine coronal sections of the cerebral hemispheres, blocks were taken of the hippocampal region for light microscopy (LM), transmission electron microscopy (TEM) and SEM. At low magnifications, the different anatomical regions can be clearly identified as well as the interlocking of the dentate gyrus and the cornu Ammonis. At higher magnifications, the detailed micro-anatomical structures can be resolved. The fimbria and alveus are composed of a closely packed network of fibrils. Within the lateral ventricle, the ependymal cells are ciliated. The choroid plexus shows clusters of polygonal cells which have a brushlike border due to the presence of numerous stubby microvilli on the surface of the cells. The granular layer of the dentate gyrus is compact due to the intimate but irregular apposition of the cells resembling the dentition in malocclusion. The neuronal bodies are mostly fusiform but may taper into a flask shape. The neurons of the molecular and of the polymorphic molecular layers are much smaller and they are more widely scattered. In the hippocampal formation, the pyramidal layer stands out most clearly as its cells are larger and more angular than those of the other layers. A classical pyramidal morphology may be well shown. A very rich plexus of fibers is found in the stratum lacunosum.

Adult↗
PubMed1983

The application of scanning electron microscopy in the clinical investigation of the human colon.

Scanning electron microscopy (SEM) of the human colon has extended the observations on gross examination and colonoscopy to ultrastructural levels. It has given a clear demonstration of submicroscopic cell surface details such as microvilli and has shown diagnostic alterations of surface topography in benign and malignant neoplasia. SEM investigation of Crohn's disease and of Clindamycin-associated colitis has shed light on the pathogenesis of the disease process. The results of the latter study demonstrated its application as an aid in the definitive establishment of the clinical diagnosis. At all times, the SEM findings have been correlated with those of light (LM) and/or transmission electron microscopy (TEM). There are advantages and disadvantages to each one of these types of microscopy. SEM serves to complement the other two and to broaden the spectrum of morphological examination.

Adenoma↗
PubMed1981

Scanning electron microscopy of mucosal biopsies of the human upper gastrointestinal tract.

There have been comparatively few scanning electron microscopic studies of mucosal biopsies of the human upper gastrointestinal tract. This report deals with the results of scanning electron microscopy of 21 mucosal biopsies: 7 esophageal, 2 from the gastroesophageal junction, 3 gastric and 9 duodenal biopsies. Mucosal biopsies were obtained at the time of fiberoptic endoscopy and were placed immediately into 2.5% glutaraldehyde in phosphate buffer, pH 7.4. After post-fixation and removal of mucus, tissue was processed by means of the O-T-O method, Dehydrated, critical point dried with CO2 and examined at 20kV. Scanning electron microscopy (SEM) of mucosal biopsies of the esophagus shows a mosaic pattern. Cell borders are clearly demarcated and there are find microridges on the luminal surface. There are varying degrees of detachment and desquamation of the superficial cells. Acute esophagitis was observed in 2 of the biopsies. At the gastro-esophageal junction, the squamous epithelium of the esophagus abuts in a jagged manner upon the columnar epithelium of the stomach. The SEM appearance of the gastric mucosa is characterized by the presence of hillocks with central depressions formed by the gastric pits. Flattening of the hillocks and invagination into the gastric pits were seen in a biopsy of a fold at a Billroth I anastomosis. The villi of the duodenal mucosa form tongue-like of finger-like projections. The luminal surface of the absorptive cells has a dense covering of microvilli. The openings of goblet cells are studied on the mucosa as minute depressed foci. Varying degrees of an acute inflammatory reaction were present in 5 duodenal biopsies. It is concluded that SEM should prove to be of value as an aid in the diagnosis of mucosal biopsies of the human upper gastrointestinal tract.

Adult↗
PubMed1980

Scanning electron microscopy of the adult human testis.

Scanning electron microscopy was performed on adult human testicular tissue using fresh orchiectomy and some recent autopsy material. After preliminary fixation in 2.5% glutaraldehyde in phosphate buffer, pH 7.4, blocks were taken for scanning electron microscopy and for correlative light and transmission electron microscopy,. For scanning electron microscopy, the tissue was processed by means of the osmium-thiocarbohydrazide-osmium method, dehydrated and critical point dried with CO2. Blocks taken from the periphery of the testis showed the presence of the tunica albuginea, which formed a comparatively dense encapsulation around the testis. Large blood vessels were present at points along the innermost layer of the tunica. Within the testis, the vessels became progressively smaller and came into close apposition to the seminiferous tubules. Individual tubules could be identified from the lowest magnification (15x). They were seen both as intact, intricately convoluted structures and at all levels and planes of transection. Within the tubules, the seminiferous epithelium was seen both in the intact and transected state. All of the cell types, were identified. In the basal layer, in contact with the basement membrane, there were spermatogonia and varying numbers of Sertoli cells. Spermatocytes were located in the mid-zone of the tubule and spermatids in the adluminal compartment. There were numerous tails of spermatozoa projecting into the lumen. Normal spermatozoa, some round headed forms and an occasional bizarre multiheaded spermatozoon were observed. Leydig cells were noted in the intertubular angles and in close proximity to blood vessels.

Adult↗
PubMed1979

Investigation of crystallosis of the kidney by means of polarization, scanning, transmission and high-voltage electron microscopy.

This report deals with the investigation of renal crystallosis in the autopsy tissue of a fatal human case of ethylene glycol poisoning. A previously healthy 22-year-old man consumed about one liter of Prestone antifreeze, which contains 95% by weight of ethylene glycol. He died in coma 48 h later with clinical evidence of metabolic acidosis and renal shutdown. Postmortem histological examination showed abundant crystallosis of the renal tubules. Polarization microscopy demonstrated brilliant birefringence of the crystals. In addition to the tubular crystallosis, scanning electron microscopy showed crystalline particles within the glomeruli as well. Energy dispersive X-ray analysis of the crystals gave a strong calcium signal. The crystals were demonstrated by means of conventional and high-voltage electron microscopy. Electron diffraction gave several hexagonal patterns of calcium carbonate-calcite and a tetragonal pattern suggestive of calcium oxalate monohydrate. X-ray diffraction of the crystals separated from the kidney showed the presence of calcium carbonate and calcium oxalate monohydrate as the major constituents.

Adult↗