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Biomedical subjects

C F Lo

Publications and source records attributed to C F Lo.

At least 19 recordsLinked to original sources
PubMed2003

Outcome of calf deep-vein thrombosis after total knee arthroplasty.

We investigated the outcome of deep-vein thrombosis (DVT) in the calf after total knee arthroplasty (TKA) in 48 patients (45 women and three men) by clinical assessment and venographic study between three and four years after surgery. The mean age of the patients was 67.2 +/- 7.7 years (52 to 85) and the mean follow-up was 42.6 +/- 2.7 months (38 to 48). The diagnosis was osteoarthritis in 47 patients and rheumatoid arthritis in one patient. There were 44 calf thrombi, four popliteal thrombi but no thrombi in the femoral or iliac regions. Of the 48 patients, 24 were clinically symptomatic and 24 were asymptomatic. Clinical examination was carried out on 41 patients, of whom 37 underwent ascending venography. Seven were evaluated by telephone interview. No patient had the symptoms or signs of recurrent DVT, venous insufficiency in the affected leg, or a history of pulmonary embolism. No patient had been treated for complications of their DVT. Thirty-six of the 37 venographic studies were negative for either old or new DVT in the affected leg. One patient had residual thrombi in the muscular branches of the veins. Our study shows that deep-vein thromboses in the calf after TKA disappear spontaneously with time. No patient developed a recurrent DVT, proximal propagation or embolisation. Treatment of DVT in the calf after TKA should be based on the severity of the symptoms during the immediate postoperative period.

Aged↗
PubMed2001

Cloning, characterization, and phylogenetic analysis of a shrimp white spot syndrome virus gene that encodes a protein kinase.

An open reading frame (ORF) that encodes a 715-amino-acid polypeptide was found in an 8421-bp EcoRI fragment of the shrimp white spot syndrome virus (WSSV) genome. The polypeptide shows significant homology to eukaryotic serine/threonine protein kinase (PK) and contains the major conserved subdomains for eukaryotic protein kinases. Coupled in vitro transcription and translation generated a protein having an apparent molecular mass of about 87 kDa according to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. For transcriptional analysis of the pk gene, total RNA was isolated from WSSV-infected shrimp at different times after infection. Northern blot analysis with pk-specific riboprobe found a major and a minor transcript of 2.7 and 5.7 kb, respectively. Rapid amplification of the 5' cDNA ends of the major 2.7-kb pk transcript showed that there were two transcriptional initiation sites located at nucleotide residues -38(G) and -39(G) relative to the ATG translational start codon. Temporal expression analysis by RT-PCR indicated that the transcription of the pk gene started 2 h after infection and continued for at least 60 h. Phylogenetic analysis showed that WSSV protein kinase does not have any close relatives and does not fall into any of the major protein kinase groups.

3' Untranslated Regions↗
PubMed2001

Performance of WSSV-infected and WSSV-negative Penaeus monodon postlarvae in culture ponds.

In a survey of 27 Penaeus monodon culture ponds stocked with postlarvae (approximately PL10) at medium density (approximately 40 shrimp m(-2)), single-step nested white spot syndrome virus (WSSV) PCR was used to measure the WSSV infection rates in the shrimp populations within 1 mo after stocking. Seven ponds were initially WSSV-free, and the shrimp in 5 of these were harvested successfully. In the ponds (n = 6) where detection rates were higher than 50%, mass mortality occurred during the growth period, and none of these ponds was harvested successfully. In a subsequent study, P. monodon brooders were classified into 3 groups according to their WSSV infection status before and after spawning: brooders that were WSSV-positive before spawning were assigned to group A; spawners that became WSSV-positive only after spawning were assigned to group B; and group C consisted of brooders that were still WSSV-negative after spawning. WSSV screening showed that 75, 44 and 14%, respectively, of group A, B and C brooders produced nauplii that were WSSV-positive. Most (57%; 16/28) of the brooders in group A produced nauplii in which the WSSV prevalence was high (>50%). When a pond was stocked with high-prevalence nauplii from 1 of these group A brooders, an outbreak of white spot syndrome occurred within 3 wk and only approximately 20% of the initial population survived through to harvest (after 174 d). By contrast, 2 other ponds stocked with low-prevalence and WSSV-negative nauplii (derived respectively from 2 brooders in group B), both had much higher survival rates (70 to 80%) and yielded much larger (approximately 3x by weight) total harvests. We conclude that testing the nauplii is an effective and practical screening strategy for commercially cultured P. monodon.

Animals↗
PubMed2001

beta -Amyloid peptide-induced apoptosis regulated by a novel protein containing a g protein activation module.

Degeneration of neurons in Alzheimer's disease is mediated by beta-amyloid peptide by diverse mechanisms, which include a putative apoptotic component stimulated by unidentified signaling events. This report describes a novel beta-amyloid peptide-binding protein (denoted BBP) containing a G protein-coupling module. BBP is one member of a family of three proteins containing this conserved structure. The BBP subtype bound human beta-amyloid peptide in vitro with high affinity and specificity. Expression of BBP in cell culture induced caspase-dependent vulnerability to beta-amyloid peptide toxicity. Expression of a signaling-deficient dominant negative BBP mutant suppressed sensitivity of human Ntera-2 neurons to beta-amyloid peptide mediated toxicity. These findings suggest that BBP is a target of neurotoxic beta-amyloid peptide and provide new insight into the molecular pathophysiology of Alzheimer's disease.

Alzheimer Disease↗
PubMed2001

Hepatopancreas is the extraovarian site of vitellogenin synthesis in black tiger shrimp, Penaeus monodon.

The site of yolk protein synthesis in crustaceans has long been a subject of controversy. The vitellogenin gene structure was partially reported only very recently in Macrobrachium rosenbergii, after which the hepatopancreas was confirmed as the extraovarian site of vitellogenin synthesis in that species. Ovaries are the most frequently reported as the site of yolk protein synthesis in penaeid shrimp. Using cDNA reversed-transcribed from mRNA isolated from the hepatopancreas of vitellogenic female shrimp, Penaeus monodon, we found that its deduced amino acid sequence had high identity of 48% with that from M. rosenbergii vitellogenin. A similar location of the intron in the sequenced region of genomic DNA was also found between these two species. We therefore concluded that the hepatopancreas the extraovarian site of vitellogenin synthesis in P. monodon in vivo. The partial structure of vitellogenin gene is presented in this study.

Amino Acid Sequence↗
PubMed2000

Ultrastructural justification for the transfer of Pleistophora anguillarum Hoshina, 1959 to the genus Heterosporis Schubert, 1969.

This study presents the ultrastructure of the microsporidian infecting the trunk musculature of Anguilla japonica and originally described as Pleistophora anguillarum Hoshina, 1959. All stages develop within a special structure, the sporophorocyst (SPC), which is equipped with a thick dense wall. This wall grows along with the growth of the parasites within it. Meronts are uni- to binucleate, which divide and steadily give rise to sporonts. During transition to sporonts the cell coat of the meronts increases its thickness, temporarily featuring thick irregular projections. Eventually a uniformly thick sporont wall is formed, then the sporont cells detach themselves from the wall (= future wall of the sporophorous vesicle, SPV) and start a series of divisions to produce sporoblasts. The SPV wall is compact, has no pores and consists of 2 layers. The presence of the SPC justifies the transfer of the species into the genus Heterosporis. Spores from disrupted SPCs are ingested by macrophages and within them are spread into various body tissues including the outermost layers of the epidermis. From here, they can easily be released to the outside and can contaminate the environment while the host is still alive.

Anguilla↗
PubMed2000

Transcriptional analysis of the ribonucleotide reductase genes of shrimp white spot syndrome virus.

The causative agent of white spot syndrome (WSS) is a large double-stranded DNA virus, WSSV, which is probably a representative of a new genus, provisionally called Whispovirus. From previously constructed WSSV genomic libraries of a Taiwan WSSV isolate, clones with open reading frames (ORFs) that encode proteins with significant homology to the class I ribonucleotide reductase large (RR1) and small (RR2) subunits were identified. WSSV rr1 and rr2 potentially encode 848 and 413 amino acids, respectively. RNA was isolated from WSSV-infected shrimp at different times after infection and Northern blot analysis with rr1- and rr2-specific riboprobes found major transcripts of 2.8 and 1.4 kb, respectively. 5' RACE showed that the major rr1 transcript started at a position of -84 (C) relative to the ATG translational start, while transcription of the rr2 gene started at nucleotide residue -68 (T). A consensus motif containing the transcriptional start sites for rr1 and rr2 was observed (TCAc/tTC). Northern blotting and RT-PCR showed that the transcription of rr1 and rr2 started 4-6 h after infection and continued for at least 60 h. The rr1 and rr2 genes thus appear to be WSSV "early genes."

Amino Acid Sequence↗
PubMed2000

Identification and characterization of a shrimp white spot syndrome virus (WSSV) gene that encodes a novel chimeric polypeptide of cellular-type thymidine kinase and thymidylate kinase.

From previously constructed genomic libraries of a Taiwan WSSV isolate, a putative WSSV tk-tmk gene was identified. Uniquely, the open reading frame (ORF) of this gene was predicted to encode a novel chimeric protein of 388 amino acids with significant homology to two proteins: thymidine kinase (TK) and thymidylate kinase (TMK). Northern blot analysis with a WSSV tk-tmk-specific riboprobe detected a major transcript of 1.6 kb. When healthy adult Penaeus monodon shrimp were inoculated with WSSV, the tk-tmk gene transcript was first detected by RT-PCR analysis at 4 h postinfection and transcription levels continued to increase over the first 18 h. The gene's major in vitro transcription and translation product, equivalent to the predicted size (43 kDa), is a single chimeric protein that includes both the TK and TMK functional motifs. Evidence for phylogenetic analysis and sequence alignment suggested that the gene may have resulted from the fusion of a cellular-type TK gene and a cellular-type TMK gene. Its unique arrangement may also provide a valuable gene marker for WSSV.

Amino Acid Sequence↗
PubMed2000

Ultrastructure of white spot syndrome virus development in primary lymphoid organ cell cultures.

Primary cell cultures from the lymphoid organ of Penaeus monodon were used to investigate in vitro propagation and morphogenesis of white spot syndrome virus (WSSV). Double-strength Leibovitz's L15 supplemented with 20% fetal bovine serum, pH 7.5, with a final osmolarity of 530 +/- 5 mOsm kg-1 was identified as the most suitable culture medium. In this medium, the lymphoid cells remained viable for more than 1 wk. Migrating cells were inoculated with WSSV, and the consequent cytopathic effects documented by light and electron microscopy. WSSV appears capable of following 2 alternative assembly sequences, one similar to the morphogenesis of the Oryctes rhinocerus virus and another which is more typical of baculoviral assembly. Possible relationships between WSSV, Oryctes virus, and baculoviruses are discussed.

Animals↗
PubMed2000

Diagnosis of Penaeus monodon-type baculovirus by PCR and by ELISA of occlusion bodies.

The black tiger prawn Penaeus monodon is a valuable aquaculture product in Taiwan. Two specific diagnostic methods were established for P. monodon-type baculovirus, one using polymerase chain reaction (PCR) technology and the other enzyme-linked immunosorbent assay (ELISA) technology. Monodon-type baculovirus (MBV) was purified by sucrose gradient centrifugation from occlusion bodies of MBV-infected postlarvae of P. monodon. MBV DNA was subsequently purified from the occlusion bodies and its presence was confirmed by PCR using primers of the polyhedrin gene. Based on conserved sequences of the DNA polymerase genes of Autographa californica nuclear polyhedrosis virus (AcMNPV) and Lymantria dispar nuclear polyhedrosis virus (LdMNPV), primers were designed and synthesized to yield a 714 bp PCR fragment from MBV. However, the sequence of this fragment revealed low homology with that of LdMNPV and AcMNPV. From the DNA sequence of this fragment, a second set of primers was designed, and using these primers, a 511 bp DNA fragment was amplified only when MBV DNA was the template. DNA templates from AcMNPV, white spot syndrome diseased shrimp, or PMO cells (a cell line derived from the Oka organ of Penaeus monodon) did not give any amplified DNA fragment. Therefore, this primer pair was specific for the diagnosis of MBV. By using intraspleenic immunization of rabbits with purified MBV occlusion bodies, a polyclonal rabbit antiserum against MBV was obtained. This antiserum could detect nanogram levels of MBV, but did not cross react with white spot syndrome virus (WSSV), homogenates of PMO cells, postlarvae, hepatopancreatic tissue or intestinal tissue of black tiger prawns by competitive ELISA. This sensitive method could detect MBV even in tissue homogenates.

Animals↗
PubMed2000

Natural and experimental infection of white spot syndrome virus (WSSV) in benthic larvae of mud crab Scylla serrata.

White spot syndrome virus (WSSV), the causative agent of white spot syndrome in shrimp, has a wide host range which extends to crabs, copepods and other arthropods. In this study, benthic larvae of the mud crab Scylla serrata were captured from Taiwan's coastal waters and screened for the presence of WSSV by polymerase chain reaction (PCR) and in situ hybridization. WSSV was detected in around 60% of the larvae, and this prevalence rate remained fairly constant when the captured larvae were subsequently maintained in an aerated system in the laboratory. WSSV-free larvae obtained from a hatchery were challenged by immersion in a WSSV inoculum. Fifteen days after challenge, cumulative mortality in the experimental group reached 43% compared to 20% in the control group. PCR detection of WSSV in both moribund and surviving specimens clearly implicated the virus as the cause of death in most cases. Histological and in situ hybridization data confirmed that WSSV tissue tropism in Scylla serrata crab larvae is similar to that found in shrimp.

Animals↗
PubMed2000

Nested polymerase chain reaction and in situ hybridization for detection of nucleopolyhedrosis.

A nested polymerase chain reaction (PCR) and in situ hybridization were developed for detection of baculoviruses in insects or other arthropods with nucleopolyhedrosis. The nested PCR was based on the sequences of polyhedrin genes from baculoviruses. Two sets of primers were designed, primers set, 35/36, was for the first step of amplification and yielded a product of around 680 bp, the second primer, 35-1/36-1, was designed to yield a product of around 335bp from the fragment amplified by the first primer set. The sensitivity of this two-step amplification was 100 to 1000 times higher than that of the one-step amplification by primer set (35/36). Samples which contained baculovirus DNA yielded an amplification product showing the expected DNA fragment mobility, whereas nucleic acid extracted from tissue samples of clinically healthy insects or uninfected cells showed no such DNA fragment, thereby confirming the specificity of the primers. Using the 35/36 amplicon as a probe, the PenuNPV-infected cells show positive reaction by in situ hybridization. Two-step DNA amplification and in situ hybridization with the DNA probe developed in the present paper provide effective detection and diagnostic tools for screening insects or other arthropods, especially crustacean species, crabs and shrimps, for baculovirus infections, and may be important in preventing (and/or controlling/enhancing) the infection of baculoviruses.

Animals↗
PubMed2000

Analysis of a genomic segment of white spot syndrome virus of shrimp containing ribonucleotide reductase genes and repeat regions.

White spot syndrome is a worldwide disease of penaeid shrimp. The disease agent is a bacilliform, enveloped virus, white spot syndrome virus (WSSV), with a double-stranded DNA genome that probably contains well over 200 kb. Analysis of a 12.3 kb segment of WSSV DNA revealed eight open reading frames (ORFs), including the genes for the large (RR1) and small (RR2) subunits of ribonucleotide reductase. The rr1 and rr2 genes were separated by 5760 bp, containing several putative ORFs and two domains with multiple sequence repeats. The first domain contained six direct repeats of 54 bp and is part of a coding region. The second domain had one partial and two complete direct repeats of 253 bp at an intergenic location. This repeat, located immediately upstream of rr1, has homologues at several other locations on the WSSV genome. Phylogenetic analysis of RR1 and RR2 indicated that WSSV belongs to the eukaryotic branch of an unrooted parsimonious tree and, further, seems to suggest that WSSV and baculoviruses probably do not share an immediate common ancestor. The present analysis of WSSV favours the view that this virus is either a member of a new genus (Whispovirus) within the Baculoviridae or a member of an entirely new virus family.

Animals↗
PubMed1999

Studies on effective PCR screening strategies for white spot syndrome virus (WSSV) detection in Penaeus monodon brooders.

We re-tested stored (frozen) DNA samples in 5 independent polymerase chain reaction (PCR) replicates and confirmed that equivocal test results from a previous study on white spot syndrome virus (WSSV) in brooders and their offspring arose because amounts of WSSV DNA in the test samples were near the sensitivity limits of the detection method. Since spawning stress may trigger WSSV replication, we also captured a fresh batch of 45 brooders for WSSV PCR testing before and after spawning. Replicates of their spawned egg batches were also WSSV PCR tested. For these 45 brooders, WSSV prevalence before spawning was 67% (15/45 1-step PCR positive, 15/45 2-step PCR positive and 15/45 2-step PCR negative). Only 27 (60%) spawned successfully. Of the successful spawners, 56% were WSSV PCR positive before spawning and 74% after. Brooders (15) that were heavily infected (i.e. 1-step PCR positive) when captured mostly died within 1 to 4 d, but 3 (20%) did manage to spawn. All their egg batch sub-samples were 1-step PCR positive and many failed to hatch. The remaining 30 shrimp were divided into a lightly infected group (21) and a 2-step PCR negative group (9) based on replicate PCR tests. The spawning rates for these 2 groups were high (81 and 78%, respectively). None of the negative spawners (7) became WSSV positive after spawning and none gave egg samples positive for WSSV. In the lightly infected group (21), 6 brooders were 2-step WSSV PCR negative and 15 were 2-step WSSV PCR positive upon capture. However, all of them were WSSV PCR positive in replicate tests and after spawning or death. Four died without spawning. The remaining 17 spawned but only 2 gave egg samples PCR negative for WSSV. The other 15 gave PCR positive egg samples, but they could be divided into 2 spawner groups: those (7) that became heavily infected (i.e. 1-step PCR positive) after spawning and those (8) that remained lightly infected (i.e. became or remained 2-step PCR positive only). Of the brooders that became heavily infected after spawning, almost all egg sample replicates (91 %) tested 2-step PCR positive. One brooder even gave heavily infected (i.e. 1-step PCR positive) egg samples. For the brooders that remained lightly infected after spawning, only 27% of the egg sample replicates were 2-step PCR positive. Based on these results, we recommend that to avoid false negatives in WSSV PCR brooder tests screening tests should be delayed until after spawning. We also recommend, with our PCR detection system, discarding all egg batches from brooders that are 1-step PCR positive after spawning. On the other hand, it may be possible with appropriate monitoring to use eggs from 2-step PCR positive brooders for production of WSSV-free or lightly infected postlarvae. These may be used to stock shrimp ponds under low-stress rearing conditions.

Animals↗
PubMed1999

A new picorna-like virus, PnPV, isolated from ficus transparent wing moth, Perina nuda (Fabricius).

Two viruses, Perina nuda nucleopolyhedrovirus and a new picorna-like virus, were previously isolated from P. nuda larvae with flacherie. In this study the new picorna-like virus was characterized using physical and biochemical methods. This small virus appears to belong to the family Picornaviridae and we propose the name PnPV. PnPV can be propagated in its homogenous cell line, NTU-PN-HH. PnPV purified from the cell line resembles PnPV isolated from insects: under electron microscopy, it exhibits icosahedral symmetry, measures 30 nm in diameter, and has no envelope and no distinct surface structure in negatively stained preparations. In addition, we show here that PnPV has a buoyant density of 1.381 g/ml in cesium chloride, the viral genome was composed of one single-stranded RNA molecule with a length of 10 kb, and poly(A) tract and polyacrylamide gel electrophoresis of purified viral particles revealed three major (31.5, 29.7, and 28.4 kDa) and three minor (27. 0, 24.5, and 4.0 kDa) structural proteins.

Animals↗
PubMed1998

Independent and exclusive modulation of cardiac delayed rectifying K+ current by protein kinase C and protein kinase A.

Expression of minK in Xenopus oocytes results in a current similar to the cardiac slow delayed rectifying K+ (IKs) current. Modulation of the IKs current in cardiac myocytes has been studied extensively because of its role in shaping the cardiac action potential. The human and cat minK cDNA have been cloned, but their regulation by protein kinases has not been characterized. We report here on the complex modulation of human and cat IKs currents by protein kinase C (PKC) and protein kinase A (PKA). Activation of PKC by phorbol ester (100 nmol/L phorbol 12,13-didecanoate [PDD]) produces an increase in IKs current that peaks after 20 minutes and then subsequently decreases to approximately 50% of the control level after 1 hour. PKA activation only produces a sustained increase in IKs current. Interestingly, premodulation by PKC prevents IKs current modulation by PKA, and PKC has no effect on IKs current after potentiation by PKA. This shows that the IKs current is modulated by PKC and PKA in a mutually exclusive manner and suggests that multiple interacting phosphorylation sites are involved. Activation of PKC by diacylglycerol analogues only produces a slow decrease in IKs current. The biphasic effects of PKC on IKs current activated by PDD can also be separated by dose and duration. Low doses of PDD (5 nmol/L) or brief applications (5 minutes) of 100 nmol/L PDD only produces IKs current activation. These data suggest that there are at least 2 independent PKC phosphorylation sites in the minK-KvLQT1 channel. Additionally, long-term activation of PKC strongly attenuates the IKs current expression even when the corresponding changes in capacitance are taken into account.

Animals↗
PubMed1997

Characterization of C3-binding proteins on mouse neutrophils and platelets.

In the mouse, MCR1 and MCR2 on B lymphocytes are encoded by alternatively spliced Cr2 gene transcripts. Immune adherence receptors that bind C3 are present on mouse platelets and unstimulated neutrophils, yet they are not MCR1 or MCR2. To examine C3b- and C3d-binding proteins on mouse platelets and neutrophils, we performed C3b and C3d affinity chromatography as well as immunoprecipitation studies using previously described Ab to MCR1/MCR2 (mAb clones 8C12, 7G6, and 7E9 and polyclonal Ab BRN-1). Mouse neutrophils contained a 190-kDa membrane protein that specifically bound to C3b-Sepharose. Preabsorption of neutrophil proteins with anti-MCR1/MCR2 Ab did not affect the recovery of the 190-kDa C3b-binding protein by subsequent C3b affinity chromatography. Thus, this protein is immunologically distinct from the previously described MCR1 and MCR2 proteins. By virtue of its size and C3b-binding capacity, the 190-kDa protein was named C3bR-190. C3bR-190 was also apparent on platelets, but in reduced amounts. BRN-1 anti-MCR1/MCR2 Ab immunoprecipitated proteins of 125 and 150 kDa from surface-radiolabeled mouse platelets, which specifically bound to C3d-Sepharose. However, these proteins were not identified by mAb to MCR2, thus distinguishing them from previously described MCR2. These proteins were named C3dR-125 and C3dR-150. Therefore, we have identified a 190-kDa C3b-binding protein on mouse neutrophils and 125- and 150-kDa C3d-binding proteins on mouse platelets. These appear to be distinct from the heretofore identified mouse B lymphocyte MCR1 and MCR2. The identity of these C3b- and C3d-binding proteins on mouse neutrophils and platelets awaits further study.

Animals↗