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Biomedical subjects

L C Ho

Publications and source records attributed to L C Ho.

At least 37 records · Page 2Linked to original sources
PubMed2000

Blastocystis elongation factor-1alpha: genomic organization, taxonomy and phylogenetic relationships.

The elongation factor-1 alpha (EF-1alpha) is a highly conserved ubiquitous protein that is involved in translation and is desirable for use in phylogenetic studies on Blastocystis, an enigmatic intestinal parasite with a contentious taxonomic position. In the present study, a PCR product (BEalpha) that codes for a major part of the coding region of the EF-lalpha protein was amplified. Genome walking experiments together with cloning were implemented to elucidate the 5' and 3' ends of the EF-1alpha gene of the human isolate, Blastocystis hominis C. The genomic organization and the potential transcription factor binding sites of the 5' end of B. hominis C EF-1alpha were identified. A comparative study on the deduced amino acid sequences of BEalpha of 13 Blastocystis isolates from various hosts was done to evaluate the phylogenetic relationship among the species. A phylogenetic reconstruction analysis with other eukaryotic EF-1alpha sequences was carried out to trace the phylogenetic position of Blastocystis among eukaryotic organisms.

Amino Acid Sequence↗
PubMed2000

Women with placenta praevia and antepartum haemorrhage have a worse outcome than those who do not bleed before delivery.

We set out to assess the maternal and neonatal outcomes of women with placenta praevia and antepartum haemorrhage (APH) between 1991 and 1997, compared with woman with a diagnosed placenta praevia who did not bleed. The demographic data, maternal and perinatal outcomes of 159 women with antepartum haemorrhage were compared with 93 women without antepartum haemorrhage in a retrospective study. Women with antepartum haemorrhage had the diagnosis of placenta praevia confirmed at an earlier gestation. More women with antepartum haemorrhage received antenatal steroids and tocolytic agents, and had emergency caesarean sections. The majority of women with bleeding had an emergency caesarean section for antepartum haemorrhage and more delivered early because of fetal distress. There were more preterm deliveries in women with antepartum haemorrhage. The mean birth weight was 2.69 kg in the women with antepartum haemorrhage and 3.06 kg in those without. More infants in the bleeding group had a low Apgar score at the first minute, respiratory distress syndrome, and admission to special baby care and neonatal intensive care unit. It is concluded that there is an increased risk of premature delivery in women with antepartum haemorrhage and placenta praevia. Aggressive management, tocolysis and cervical cerclage should be explored further to improve the perinatal outcome. Women without antepartum haemorrhage can be managed on an outpatient basis.

Journal Article↗
PubMed2000

Spontaneous uterine perforation of pyometra. A report of three cases.

BACKGROUND: Spontaneous perforation of pyometra is a rare cause of generalized peritonitis; only 17 cases have been reported. CASES: Three cases of spontaneous perforation of pyometra occurred; two were associated with carcinoma of the cervix. All were treated with exploratory laparotomy and drainage. The first patient died of recurrent carcinoma of the cervix five months after laparotomy. The second patient died of septic shock shortly after the operation. The third patient made a good postoperative recovery. CONCLUSION: Pyometra is a serious medical condition, because of both its association with malignant disease and the danger of spontaneous perforation, which carries significant morbidity and mortality. Although rare, ruptured pyometra should be considered in the differential diagnosis of acute abdomen in elderly women, especially those with malignant disorders of the genital tract. The treatment of pyometra rupture is immediate laparotomy, peritoneal lavage and drainage, or simple hysterectomy.

Abdomen, Acute↗
PubMed1999

Development of Blastocystis hominis cysts into vacuolar forms in vitro.

The development of cysts of Blastocystis hominis isolated from human feces by the Ficoll-Paque concentration method and cultured in Jones' medium containing 10% horse serum is described. The morphological changes were studied by light and transmission electron microscopy at different intervals for up to 48 h. The cysts developed into a large number of vacuolar forms within 24 h, and binary fission was the only mode of reproduction observed.

Animals↗
PubMed1999

Characterization of protein profiles and cross-reactivity of Blastocystis antigens by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analysis.

The protein profiles of Blastocystis hominis, B. lapemi, and B. ratti were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and species could be differentiated by this means as well as by Western-blot analysis with polyclonal antibodies. No intraspecies difference could be distinguished between the two B. hominis isolates or the three B. ratti isolates. Western-blot analysis showed extensive cross-reactivity of B. lapemi and B. hominis antigens with anti-B. ratti serum. Some of the cross-reactive antigens were glycoproteins as determined on the basis of their sensitivity to periodate treatment.

Animals↗
PubMed1999

In vitro encystation and excystation of Blastocystis ratti.

Cysts of Blastocystis ratti were produced in vitro by culturing the parasite in Iscove's modified Dulbecco's medium (IMDM) with increasing concentrations of horse serum. Yields up to 3 x 10(6) cysts/ml of culture medium were obtained after 72 h. Encystation efficiency was time, strain and inoculum size dependent. A viability of > 70% was determined by flow cytometry employing fluorescein diacetate and propidium iodide staining. The presence of chitin as a cyst wall component was demonstrated by Calcofluor White M2R staining with which cystic stages showed blue fluorescence. The changes in morphology during excystation were examined by transmission electron microscopy. The cyst enlarged in size and some vacuoles appeared within the condensed cytoplasm. The vacuoles were full of inclusions and small glycogen aggregates. Coalescence of the vacuoles led to central body formation. Glycogen deposits were prominent throughout the excystation process. Some cysts divided by binary fission before the completion of the excystation.

Animals↗
PubMed1998

Cytopathic effect of Blastocystis hominis after intramuscular inoculation into laboratory mice.

The present study investigated the pathogenesis of Blastocystis hominis by intramuscular injection of the organism into experimental mice. A total of 27 naïve BALB/c mice aged 6-8 weeks were injected in the leg muscle with axenic culture isolate B of B. hominis. Histological examination at different times revealed that B. hominis could produce a severe inflammatory reaction and myonecrosis. Most changes were observed at 6 h after injection and for up to 2-3 days. By 2 weeks the muscle had regained normal histology. There was infiltration of polymorphonuclear leukocytes (PML) into the injection site, indicating that B. hominis had a strong chemoattractant activity for PML.

Animals↗
PubMed1998

Well-differentiated papillary adenocarcinoma arising in a supratentorial enterogenous cyst: case report.

OBJECTIVE AND IMPORTANCE: We report a case of a well-differentiated papillary adenocarcinoma arising in an supratentorial enterogenous cyst. The clinicopathological features of this case and a brief review of the literature are presented. CLINICAL PRESENTATION: A 45-year-old woman presented with abrupt onset of sensory seizures and abnormal sensation on the left side of her face, left leg, and left arm. Radiological studies showed a cystic extraaxial tumor with mass effect in the right parietal area. The initial clinical impression was a metastatic lesion, and a comprehensive metastatic workup revealed no evidence of tumor elsewhere. INTERVENTION: A gross total resection of the solid cystic tumor was achieved by a frontoparietal craniotomy. Sixteen months after the initial surgery, the patient presented with signs of increased intracranial pressure and a large parietal cyst. The cyst was fenestrated at the time of the second craniotomy. CONCLUSION: A pathological study of the initial surgical material revealed it to be a well-differentiated papillary adenocarcinoma in association with an enterogenous cyst. The second surgical specimen consisted only of the benign cyst wall. The patient recovered uneventfully from the second surgery and was free of symptoms 6 months postoperatively. The importance of recognizing the rare possibility of malignant progression of a benign enterogenous cyst in the central nervous system is discussed.

Adenocarcinoma, Papillary↗
PubMed1998

Labour outcome of low-risk multiparas of 40 years and older. A case-control study.

Between January 1, 1994 and December 31, 1997 a total of 76 low-risk multiparas of 40 years and older with spontaneous onset of labour were delivered and were compared with 152 younger (25-30 years-old) low-risk multiparas of similar parity in a case-control study. The labour and perinatal outcomes of the 2 groups were compared. The duration of the first stage of labour was longer (233 minutes versus 149 minutes, p<0.0005) in the older women. Significantly more labours of older multiparas were complicated by intrapartum fetal distress (6.6% versus 1.3%, p<0.05); received intramuscular analgesia (11.8% versus 2.6%, p<0.01); and had operative deliveries (17.1% versus 4.6%, p<0.01). The incidence of instrumental delivery (11.8% versus 3.9%, p<0.05) and Caesarean section (5.3% versus 0.7%, p<0.05) were higher among older multiparas. The incidences of Syntocinon augmentation of labour, prolonged second stage, episiotomy and third stage complications such as perineal tear, primary postpartum haemorrhage, and retained placenta were similar in both groups. Both groups had similar perinatal outcomes. These women should be treated as others with high-risk pregnancies with appropriate careful attention during labour such as continuous fetal heart rate monitoring. They should be counselled to be made aware of the increased risks during labour.

Adult↗
PubMed1997

Description of a Blastocystis species from Rattus norvegicus.

Two isolates (WR1 and WR2) of Blastocystis from laboratory-bred Wistar rats were axenized by a method of colony growth in soft agar combined with antibiotic treatment. The colonies were cultured in Iscove's modified Dulbecco's medium (IMDM) and Bacto agar mixture supplemented with 10% horse serum in the presence of thioglycollate. The cells from the colonies had an ameboid outline with a central body. Large inclusions were seen in the central body of some cells. Some granular forms were also found. In the axenic culture of isolate WR2, about one-third of the organisms were granular forms. Cysts were found in the axenic culture of both isolates. This is the first report of such cyst formation in in vitro culture. The karyotypic patterns of both isolates of the rat Blastocystis were analyzed by pulsed-field gel electrophoresis (PFGE). A total of 13 chromosomal bands were separated, ranging from 1.86 Mb to 295 kb. The karyotypic patterns of the rat Blastocystis were different from those of B. hominis and reptilian Blastocystis. On the basis of the above-mentioned differences, the rat Blastocystis is assigned as B. ratti sp. nov.

Animals↗
PubMed1997

Experimental Blastocystis hominis infection in laboratory mice.

Young (less than 8 weeks old) immunocompetent BALB/c mice became infected with Blastocystis hominis after inoculation of fecal cysts orally and of in vitro axenic-culture forms intracecally. This study confirmed that the fecal cyst was the form responsible for external transmission and that the mode of transmission was by the fecal-oral route. The infection was self-limiting and the infected BALB/c mice appeared normal except that some of them showed weight loss and lethargy. Both vacuolar and granular forms were found in the cecum, but only cyst forms were observed in the colon. Histological examination of the cecum and colon showed intense inflammatory-cell infiltration, edematous lamina propria, and mucosal sloughing. It is apparent that although B. hominis is not invasive, it is capable of causing pathogenesis in BALB/c mice.

Animals↗
PubMed1997

Survival of Blastocystis hominis clones after exposure to a cytotoxic monoclonal antibody.

Our previous studies have shown that monoclonal antibodies (MAbs) to Blastocystis hominis react mainly with carbohydrate epitopes, while 1 MAb (1D5) reacts specifically with a protein of 30.5 kDa. In the present study, 3 monoclonal antibodies (1D5, 1E7 and 4F7) were used in immunogold localization. 1E7 and 4F7 were found to react primarily with the surface coat, while 1D5 was plasma membrane-specific. In the presence of complement, only 1D5 exhibited a cytotoxic effect on B. hominis whereas 1E7 and 4F7 did not, suggesting that the surface coat of B. hominis could serve as an immunological barrier against host antibodies. Using a recently described agar plating method, only 1D5 exhibited significant (P < 0.01) complement-independent cytotoxicity to B. hominis, inhibiting colony growth at low concentrations. Parasites that had been exposed to 1D5 were morphologically smaller than those that were not exposed to this MAb. Colonies that grew in the presence of 1D5 were isolated and grown in liquid medium containing increasing amounts of the cytotoxic MAb. Two clones that grew well in liquid medium containing 1D5 were also able to develop into colonies in soft agar. This study has shown that the 30.5 kDa protein found on the plasma membrane of B. hominis is a functionally important protein and that not all cells within a certain population would be susceptible to the cytotoxic effects of 1D5. These findings suggest that a heterogenous population exists in continuously maintained cultures of B. hominis.

Animals↗
PubMed1996

Axenic culture of reptilian Blastocystis isolates in monophasic medium and speciation by karyotypic typing.

The growth of axenic reptilian isolates of Blastocystis in Iscove's modified Dulbecco's medium (IMDM) was studied and the morphology of the parasite was examined by phase-contrast microscopy. The chromosomal patterns of these reptilian isolates of Blastocystis were examined by pulsed-field gel electrophoresis (PFGE) and compared with those of B. hominis and B. lapemi, a sea snake Blastocystis. IMDM with 10% horse serum supported excellent growth of the reptilian Blastocystis isolates. The parasites from all the isolates were predominantly vacuolar, but multivacuolar and amoeboid forms were also seen. Amoeboid forms with rather elongate pseudopodia were also observed. There were some differences in size, morphology, and growth characteristics in the different reptilian isolates. The karyotypic patterns of the Blastocystis isolates from tortoise, iguana, and python were distinctly different from one another and from those obtained with B. hominis and B. lapemi. On the basis of the above-mentioned differences in chromosomal patterns, the tortoise, iguana, and python isolates are described as new species, viz., B. geocheloni sp. nov. from Geochelone carbonaria (red-footed tortoise), B. cycluri sp. nov. from Cyclura cornuta (rhino iguana), and B. pythoni sp. nov. from Python reticulatus (reticulated python).

Animals↗
PubMed1996

Colony formation of Blastocystis hominis in soft agar.

This is the first description of a method for growing axenized Blastocystis hominis as colonies in petri dishes containing soft agar. Blastocystis cells cultured in two types of agar appeared to show different colonial morphologies as well as differing colony yields. Microscopic examination of the colonies revealed many amoeboid and giant cells. Many cells were also shown to possess thin filament-like structures that appeared to stretch across the central vacuole.

Agar↗
PubMed1996

Observations on the ultrastructure and viability of the cystic stage of Blastocystis hominis from human feces.

This report describes the ultrastructure and viability of cysts of Blastocystis hominis from feces of infected patients. The cysts were round to ovoid, measured 2-5 microns in size, and contained a condensed cytoplasm that had vacuoles of varying sizes, four nuclei, and as many as six cristate mitochondria. The cell wall was rather electron-lucent. Surprisingly, chromatoid-like structures were found in the cytoplasm and nucleus of some of the cysts. These have not previously been reported in Blastocystis. The cysts can survive in water for up to 19 days at normal temperatures but are fragile at extreme temperatures and in common disinfectants.

Animals↗
PubMed1996

Clonal growth of Blastocystis hominis in soft agar with sodium thioglycollate.

The present report describes a method for establishment of colonies of Blastocystis hominis from single cells in soft agar. The percentage of colony-forming efficiency (% CFE = number of colonies grown/number of cells inoculated x 100) for the cultures was greatly improved by the addition of sodium thioglycollate. Five human Blastocystis isolates chosen for this study showed no apparent variation in colonial morphology. Isolated colonies were also successfully grown in liquid medium, providing a means of obtaining large numbers of B. hominis cells that had arisen from a single clone.

Animals↗