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Biomedical subjects

W L Lin

Publications and source records attributed to W L Lin.

At least 109 records · Page 6Linked to original sources
PubMed1989

CSF neurochemical study of tardive dyskinesia.

Twenty-three inpatients who met DSM-III criteria for schizophrenia were selected for cerebrospinal fluid (CSF) neurochemical study of tardive dyskinesia (TD). Ten inpatients had tardive dyskinesia, and the remaining 13 patients without TD served as controls. There were no intergroup differences in sex, age, duration of neuroleptic treatment, or in total amount of neuroleptics received between the TD and the control groups. Cerebrospinal fluid was collected by lumbar puncture, and concentrations of homovanillic acid (HVA), MHPG, 5-hydroxyindoleacetic acid (5-HIAA), and acetylcholinesterase (AChE) activity were measured. The concentrations of MHPG (TD 11.56 +/- 3.48 ng/ml versus control 14.20 +/- 3.86 ng/ml), 5-HIAA (45.27 +/- 9.77 ng/ml versus 40.34 +/- 13.77 ng/ml), and HVA (38.26 +/- 18.31 ng/ml versus 31.40 +/- 7.83 ng/ml), and the activity of AChE (TD 7.95 +/- 5.21 mmol/g.hr versus control 12.89 +/- 8.04 mmol/g.hr) showed no significant differences between the two groups, but the ratios of HVA/AChE (t = 2.21, p = 0.05), 5-HIAA/AChE (t = 2.62, p = 0.02), MHPG/HVA (t = -2.16, p = 0.04), and MHPG/5-HIAA (t = -2.48, p = 0.02) were statistically different. The results indicated that TD might involve an imbalance of dopamine-acetylcholine, noradrenalin-dopamine, noradrenalin-serotonin, and serotonin-acetylcholine.

Acetylcholinesterase↗
PubMed1989

Immunogold localization of extracellular matrix molecules in Bruch's membrane of the rat.

The distribution of extracellular matrix molecules in Bruch's membrane of the rat was studied by a post-embedding immunogold labeling method. These molecules included laminin, types I, III and IV collagen, fibronectin and heparan sulfate proteoglycan. Laminin and type IV collagen were localized in the basal lamina of the pigment epithelium and choriocapillaris; types I and III collagen, to the inner and outer collagenous zones; fibronectin, to the elastic layer; heparan sulfate proteoglycan was found diffusely throughout the entire Bruch's membrane. These results not only agree with previous biochemical and immunofluorescence studies of these molecules in Bruch's membrane of other species but also provide a more precise localization of these molecules in the various layers of Bruch's membrane.

Animals↗
PubMed1989

Plasma homovanillic acid in schizophrenics: supportive evidence for the two-subtype hypothesis.

Plasma levels of homovanillic acid (pHVA), a major metabolite of dopamine (DA), were measured in a group of 51 schizophrenic inpatients before and during 6 weeks of neuroleptic treatment. Steady-state plasma drug concentrations were monitored in parallel with pHVA. Good responders (n = 22) had higher pretreatment pHVA levels as compared to poor responders (n = 22). Differential pHVA changes during neuroleptic treatment were also found between each group. The two groups did not differ significantly in terms of age, duration of illness, severity of presenting symptoms, neuroleptic, dose, or plasma drug concentration. Two hypothetical subtypes in the group of schizophrenics were proposed.

Adult↗
PubMed1989

[Harlequin fetus--a case report].

A one-day-old male premature baby was born to a G4P4 mother with the gestation age of 30 weeks. His birth weight was 2000 gm. He was noted to be covered with a thick, armor-like skin which is split by deep fissures and makes the feature of Ectropion and eclabium. His nose was flattened, only the nostrils were visible, and the external ears were underdeveloped. The hands and feet appeared to be swollen and crumpled. The genital organ was covered with thick fissured skin and it was impossible to distinguish sex by external appearance. Three days after delivery, the patient died of respiratory distress. He was found normal through general laboratory and chromosome study. However, dermatohistology showed hyperkeratosis, focal parakeratosis and hypogranulosis. Pathology showed PDA (patent ductus arteriosus), enlarged thymus and congestion of internal organs. Its etiology and pathogenesis somehow remain unknown. We hereby reported this harlequin fetus, the most severe type of lamellar ichthyosis, and discussed its incidence, pathogenesis, pathohistology, prognosis and the recent development in treatment.

Abnormalities, Multiple↗
PubMed1988

Leakage of blood-retinal barrier due to damaging effect of protamine sulfate on the endothelium.

The effect of the polycations, protamine sulfate and poly-L-lysine, on the blood-retinal barrier of rat retinal vessels were studied by retrograde perfusion through the aorta or by intracarotid perfusion of the polycation followed by the protein tracer, hemoglobin. Protamine sulfate induced swelling of cytoplasmic organelles and diffuse staining of many endothelial cells by tracer molecules which subsequently entered the subendothelial and perivascular areas. Polylysine caused some diffuse staining but no leakage of tracer through the endothelial cell. Occasionally, tracer was found in the interendothelial junction after protamine perfusion. The results indicate that surface charge is important for maintaining membrane integrity of the endothelial cells and that breakdown of the blood-retinal barrier may be due to the cytotoxic effect of protamine on the endothelial cell.

Animals↗
PubMed1988

Ultrastructural and permeability characteristics of retinal vessels in stroke-prone spontaneously hypertensive rats.

The ultrastructure and permeability of retinal arterioles, venules, and capillaries located near the optic disc of stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar-Kyoto rats were studied using electron microscopy and tracer cytochemistry. A variety of structural changes were observed in arterioles of SHRSP. They include (1) narrowing of the lumen due to smooth muscle hyperplasia and/or fragmentation and thickening of the basal lamina, (2) fusiform aneurysms containing degenerated smooth muscle cells and reduplicated basal lamina, and (3) the presence of microfilament bundles under the luminal surface of the endothelium. In addition, the wall of venules was thickened due to accumulation of basal lamina material. Many capillary pericytes were also degenerated. Retinal vessels of age-matched normotensive rats did not show such changes. In SHRSP, after injection of peroxidase, extravasation of tracer was seen occasionally in retinal capillaries and in the central retinal vein at the optic nerve head. No changes in vascular permeability were observed in the normotensive rats.

Animals↗
PubMed1988

Immunocytochemical localization of laminin, type IV collagen and fibronectin in rat retinal vessels.

Laminin, type IV collagen and fibronectin have been identified as major components of the basement membrane (basal lamina) in various tissues. These antigens have also been identified in retinal vessels by light microscopic immunofluorescence but their precise location could not be determined at this level of resolution. In this study, we examined the localization of these constituents at the ultrastructural level using the protein A-immunoperoxidase technique. The basal lamina of all retinal capillaries, arterioles and venules was immunostained after exposure to antisera against laminin, type IV collagen and fibronectin. Staining was localized to the lamina densa, which appeared as a single or double layer. Immunostaining for fibronectin showed the weakest activity. The reaction was also seen in discrete patches between endothelial cells and pericytes. The inner limiting membrane of the retina was also reactive for laminin and type IV collagen but not for fibronectin. The results indicate that laminin, type IV collagen and fibronectin are components of the basal lamina in all types of retinal vessels. The presence of fibronectin at the endothelial-pericyte interface suggests that this protein may promote adhesion between cells and thus help to maintain the integrity of the vessel wall.

Animals↗
PubMed1988

Retinal dystrophy in Wistar-Furth rats.

A form of retinal degeneration in the Wistar-Furth strain of rat is described. The changes observed was classified as either mild or severe, depending on the severity of the dystrophy seen by light and electron microscopy. In the mild stage, there was a slight decrease in the number of photoreceptor nuclei in the outer nuclear layer (ONL) and there were pyknotic nuclei in the inner nuclear layer. A few photoreceptor outer and inner segments showed focal swellings. The basal infoldings of the retinal pigment epithelium (RPE) were distributed irregularly, creating spaces that contained collagen-like fibrils. However, the interepithelial tight junctions remained impermeable to intravenously injected peroxidase. In severely dystrophic retinas, there was a further decrease in the width of the ONL, and the photoreceptor outer and inner segments were degenerated. In extreme cases, the photoreceptor cell disappeared completely and the inner retina abutted the RPE. Further changes were also noted in the basal membrane of the RPE; in some regions the membrane was totally flat while in others it formed exaggerated infoldings. In addition, the RPE was frequently vascularized by vessels that originated from the retina. The endothelium of those intra-RPE vessels located near Bruch's membrane was frequently fenestrated. Alterations also occurred in the retinal capillaries; some were degenerated, while others showed increased tortuosity or focal thickenings of the basal lamina. In addition, there were focal increases in the amount of stroma between Bruch's membrane and the choriocapillaris.

Animals↗
PubMed1987

Luminal vesicles in endothelial cells of retinal and iridial vessels of the rat.

Endothelial vesicles on the luminal front of retinal and iridial vessels were studied by perfusion fixation after intravenous injection of peroxidase, and by perfusion fixation of glutaraldehyde with tannic acid or ruthenium red. Many luminal vesicles contained peroxidase reaction product after intravenous injection of peroxidase, but were virtually empty after perfusion fixation. Both tannic acid and ruthenium red delineated the majority of luminal vesicles, singular or in clusters, surface-associated or "free" in the cytoplasm. Only a few free vesicles were unlabeled by the dye. No transendothelial channels were seen. The results suggest that most of the vesicles on the luminal front of endothelial cells are continuous with the cell surface at the time of fixation. The function of these vesicles is not fully understood; some appear to be involved in endocytosis of macromolecules from the vascular lumen.

Animals↗
PubMed1987

An electron microscopic study of retinal degeneration in Sprague-Dawley rats.

Retinal degeneration in untreated, female Sprague-Dawley rats was studied by electron microscopy and horseradish peroxidase tracer technique. The degeneration appeared to have started at a very young age. The severity of the defect varied from a decrease of photoreceptor nuclei to total loss of receptor cells and the pigment epithelium. In mild degeneration some regions of the retinal pigment epithelium became bilayered and the basal plasma membrane became flattened or formed elaborate infoldings. Breaks in Bruch's membrane occurred in severe degeneration. Degeneration of the pigment epithelium allowed permeation of tracer material from the choroid into the retina.

Animals↗
PubMed1986

Surface-associated vesicles in retinal arterioles and venules.

The surface-associated vesicles in retinal arterioles and venules were studied after fixation in glutaraldehyde-tannic acid or after intravitreal injection of peroxidase or lactoperoxidase. The vesicles were concentrated along the abluminal (basal) surface of the endothelial cells and along the plasma membranes of smooth muscle cells in arterioles and of pericytes in post-capillary venules. They were rarely encountered in the deeper regions of these cells. In perpendicular sections through the cell surface the majority of vesicles were in continuity with the plasma membrane whereas in tangential sections, they appeared to lie "free" in the cytoplasm. All such vesicles were labeled after exposure to tannic acid or to the heme-proteins. Peroxidase-reaction product was never seen in the lumen of the vessels. These observations suggest that the surface vesicles in endothelial cells, smooth muscle cells and pericytes are invaginations of the plasma membrane and are thus not involved in the transcytosis or endocytosis of proteins. The vesicles in the latter two cell types may be involved in some aspect of contractility rather than pinocytosis.

Animals↗
PubMed1986

Diffuse cytoplasmic staining of retinal capillary endothelium.

The distribution of several hemeprotein tracers in retinal capillaries of Wistar-Furth rats was studied by electron microscopic cytochemistry after incubation in 3,3'-diaminobenzidine. Diffuse cytoplasmic reaction product was frequently observed in the endothelial cells after intravenous injection of horseradish peroxidase (HRP) or lactoperoxidase (LP), or after perfusion of HRP. Occasionally, pericytes were also diffusely stained. In contrast, injection of microperoxidase, catalase, or hemoglobin did not cause diffuse staining. The diffuse staining was similar with HRP types II, VI, and VIII, and at concentrations of 2.5, 5, and 10 mg/100 g body weight. Despite the staining, the blood-retinal barrier remained intact. The findings indicate that HRP and LP are capable of causing diffuse nonspecific staining of retinal capillary endothelial cells, even at relatively low concentrations. Since these tracers are frequently used in studies of the blood-retinal barrier, the results of such studies should be interpreted with caution.

Animals↗
PubMed1984

Ribonucleoprotein organization of eukaryotic RNA. XXXI. Structure of the U1 small nuclear ribonucleoprotein.

A small nuclear ribonucleoprotein, U1 snRNP, has been implicated in mRNA processing. In this investigation sites of protein binding on U1 RNA were mapped by nuclease protection and RNA sequencing. Partially purified human U1 snRNP was sequentially digested with Escherichia coli RNAase III and S1 nuclease. The resistant ribonucleoprotein fragments were deproteinized, preparatively hybridized to the U1 RNA--complementary DNA strand of a human U1 gene cloned in bacteriophage M13, and displayed by electrophoresis. The nuclease-resistant U1 RNA fragments were between 23 and 63 nucleotides in length. Most of these fragments were not obtained when protein-free U1 RNA was similarly digested, whereas others were obtained in low yield from U1 RNA and much higher yield from U1 snRNP. RNA sequencing of the fragments revealed that the protein-protected sites in U1 snRNP correspond to base-paired stems I and II, loop a, and portions of stems III and IV (secondary structure nomenclature of Branlant et al., 1981). Single, "bulged" pyrimidines are present within the protein-covered helical regions of stems I and III. Most interestingly, the single-stranded 5' end of U1 RNA, implicated in mRNA splicing, was also highly protected by protein. These results demonstrate that the great majority of U1 RNA is covered by protein in U1 snRNP. The association of protein with the 5' end of U1 RNA is in agreement with recent evidence that snRNP proteins potentiate the binding of this region of U1 RNA with pre-mRNA splice sites.

Autoradiography↗
PubMed1984

Co-ordinate control of gene expression. Muscle-specific 7 S RNA contains sequences homologous to 3'-untranslated regions of myosin genes and repetitive DNA.

We have cloned and sequenced a complementary DNA copy (pSS48) of a novel muscle-specific, low molecular weight RNA, 7 S RNA, isolated from embryonic chick cardiac muscle cells. The hybridization pattern of plasmid pSS48 DNA to chick genomic DNA suggests that 7 S RNA is derived from the repetitive chick DNA with a repetition frequency of about 300 copies per haploid genome. Under low stringency, pSS48 DNA also hybridizes with high specificity to the single copy gene for chick myosin light chain (MLC) and to myosin heavy chain (MHC), and possibly to other co-ordinately expressed genes for chick muscle proteins. The sequence analysis of recombinant plasmids pSS48, pML10 and pMHC8, for 7 S RNA, MLC mRNA and MHC RNA, respectively, indicated that short nucleotide stretches homologous to 7 S RNA reside in the 3' untranslated regions of the respective genes. The 7 S RNA sequence appears to be highly specific for the chick muscle tissue, since RNA and DNA from several sources did not hybridize to pSS48 DNA. Furthermore, the 7 S RNA-like sequence(s) appears in chick blastodermal cells preferentially earlier than the onset of transcription of genes for major muscle proteins. These results, taken together, suggest a possible function for 7 S RNA in expression of muscle-specific genes during chick development.

Animals↗
PubMed1984

Sexual dimorphism in the Harderian gland proteins of the golden hamster.

SDS polyacrylamide gel electrophoresis of male and female hamster Harderian gland homogenates has shown a clear-cut sexual dimorphism. At least three major proteins present in the male gland are missing from the female gland. Two of the above are associated with the tubular clusters of the male gland while the third seems to be a structural component.

Animals↗
PubMed1983

Influence of short photoperiods on the ultrastructure of hamster Harderian glands.

A sexual dimorphism of the hamster Harderian gland at the ultrastructural level, has been reported. Castration of males and the administration of testosterone to females are known to alter the male type gland to the female type and vice versa. In this paper we present data that exposure to a short photoperiod (1L:23D) can induce similar structural alterations between the 4th and 10th week of exposure. Changes in the male included reduction in the number of tubular clusters and large vacuoles, while in the female the number of membrane formations decreased with an accompanying appearance of tubular clusters.

Animals↗