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P Lo

Publications and source records attributed to P Lo.

At least 19 recordsLinked to original sources
PubMed2001

Differences in tissue-specific and embryonic expression of mouse Ceacam1 and Ceacam2 genes.

The intercellular adhesion molecule CEACAM1, also known as C-CAM1 (where CAM is cell-adhesion molecule), can function as a tumour suppressor in several carcinomas, including those of the prostate, breast, bladder and colon. This suggests that CEACAM1 may play an important role in the regulation of normal cell growth and differentiation. However, there is no direct evidence to support this putative function of CEACAM1. To elucidate its physiological function by targeted gene deletion, we isolated the Ceacam genes from a mouse 129 Sv/Ev library. Although there is only one Ceacam1 gene in humans and one in rats, two homologous genes (Ceacam1 and Ceacam2) have been identified in the mouse. Our sequence analysis revealed that the genes encoded nine exons and spanned approx. 16-17 kb (Ceacam1) and 25 kb (Ceacam2). The genes were highly similar (79.6%). The major differences in the protein-coding regions were located in exons 2, 5 and 6 (76.9%, 87.0% and 78.5% similarity respectively). In addition, introns 2, 5 and 7 were also significantly different, being 29.7%, 59.8% and 64.5% similar respectively. While most of these differences were due to nucleotide substitutions, two insertions of 418 and 5849 bp occurred in intron 2 of Ceacam2, and another two insertions of 1384 and 197 bp occurred in introns 5 and 7 respectively. To determine whether functional redundancy exists between Ceacam1 and Ceacam2, we examined their expression in 16 mouse tissues by using semi-quantitative reverse transcription-PCR. As in human and rat, in the mouse Ceacam1 mRNA was highly abundant in the liver, small intestine, prostate and spleen. In contrast, Ceacam2 mRNA was only detected in kidney, testis and, to a lesser extent, spleen. Reverse transcription-PCR using testis RNA indicated that Ceacam2 in the testis is an alternatively spliced form containing only exons 1, 2, 5, 6, 8 and 9. In the mouse embryo, Ceacam1 mRNA was detected at day 8.5, disappeared between days 9.5 and 12.5, and re-appeared at day 19. On the other hand, no Ceacam2 mRNA was detected throughout embryonic development. The different tissue expression patterns and regulation during embryonic development suggest that the CEACAM1 and CEACAM2 proteins, although highly similar, may have different functions both during mouse development and in adulthood.

Adenosine Triphosphatases↗
PubMed2001

The tripeptide feG reduces endotoxin-provoked perturbation of intestinal motility and inflammation.

Lipopolysaccharide (LPS)-induced intestinal endotoxaemia perturbs motility and causes activation and influx of inflammatory cells into the muscle tissue. Because rat submandibular gland peptide T (SGP-T; Thr-Asp-Ile-Phe-Glu-Gly-Gly), its carboxyl-terminal fragment tripeptide, FEG (Phe-Glu-Gly) and its D-isomeric analogue, feG, modulate intestinal anaphylactic reactions, we examined whether these peptides also modulate LPS-induced intestinal endotoxaemia in conscious rats. The disruption of the fasting pattern of intestinal MMCs (migrating motor complexes), induced by intravenous LPS (20 microg kg-1) injection, was prevented by all three peptides. The extravasation of leucocytes into the peritoneal cavity and increased expression of the activation marker CD18 on mesenteric tissue leucocytes (18 h after intraperitoneal injection of LPS) were reduced by orally administered feG, which also significantly decreased the number of intestinal tissue leucocytes expressing the integrin CD18. We conclude that feG attenuates both the immediate (intestinal motility) and late ( approximately 18 h) inflammatory reactions provoked by endotoxaemia.

Animals↗
PubMed2001

Shunt malfunctions.

Shunt failure remains a disheartening complication of shunt surgery. The number of adjustable factors in attempting to reduce the rate is small. The clinical presentation and timing of shunt malfunction are well documented. Although the shunt design trials have been negative to date, valves have important effects that have not as yet been translated to improved outcome.

Cerebrospinal Fluid Shunts↗
PubMed2000

Hmx: an evolutionary conserved homeobox gene family expressed in the developing nervous system in mice and Drosophila.

Three homeobox genes, one from Drosophila melanogaster (Drosophila Hmx gene) and two from mouse (murine Hmx2 and Hmx3) were isolated and the full-length cDNAs and corresponding genomic structures were characterized. The striking homeodomain similarity encoded by these three genes to previously identified genes in sea urchin, chick and human, as well as the recently cloned murine Hmx1 gene, and the low homology to other homeobox genes indicate that the Hmx genes comprise a novel gene family. The widespread existence of Hmx genes in the animal kingdom suggests that this gene family is of ancient origin. Drosophila Hmx was mapped to the 90B5 region of Chromosome 3 and at early embryonic stages is primarily expressed in distinct areas of the neuroectoderm and subsets of neuroblasts in the developing fly brain. Later its expression continues in rostral areas of the brain in a segmented pattern, suggesting a putative role in the development of the Drosophila central nervous system. During evolution, mouse Hmx2 and Hmx3 may have retained a primary function in central nervous system development as suggested by their expression in the postmitotic cells of the neural tube, as well as in the hypothalamus, the mesencephalon, metencephalon and discrete regions in the myelencephalon during embryogenesis. Hmx1 has diverged from other Hmx members by its expression in the dorsal root, sympathetic and vagal nerve (X) ganglia. Aside from their expression in the developing nervous system, all three Hmx genes display expression in sensory organ development, and in the adult uterus. Hmx2 and Hmx3 show identical expression in the otic vesicle, whereas Hmx1 is strongly expressed in the developing eye. Transgenic mouse lines were generated to examine the DNA regulatory elements controlling Hmx2 and Hmx3. Transgenic constructs spanning more than 31 kb of genomic DNA gave reproducible expression patterns in the developing central and peripheral nervous systems, eye, ear and other tissues, yet failed to fully recapitulate the endogenous expression pattern of either Hmx2 or Hmx3, suggesting both the presence and absence of certain critical enhancers in the transgenes, or the requirement of proximal enhancers to work synergistically.

Amino Acid Sequence↗
PubMed2000

Three-dimensional structure of the human herpesvirus 8 capsid.

Human herpesvirus 8 (HHV-8), or Kaposi's sarcoma-associated herpesvirus, is a gammaherpesvirus implicated in all forms of Kaposi's sarcoma and certain lymphomas. HHV-8 has been extensively characterized, both biochemically and immunologically, since its first description in 1994. However, its three-dimensional (3D) structure remained heretofore undetermined largely due to difficulties in viral purification. We have used log-phase cultures of body cavity-based lymphoma 1 cells induced with 12-O-tetradecanoylphorbol-13-acetate to obtain HHV-8 capsids for electron cryomicroscopy and computer reconstruction. The 3D structure of the HHV-8 capsids revealed a capsid shell composed of 12 pentons, 150 hexons, and 320 triplexes arranged on a T=16 icosahedral lattice. This structure is similar to those of herpes simplex virus type 1 (HSV-1) and human cytomegalovirus (HCMV), which are prototypical members of alpha- and betaherpesviruses, respectively. The inner radius of the HHV-8 capsid is identical to that of the HSV-1 capsid but is smaller than that of the HCMV capsid, which is consistent with the relative sizes of the genomes they enclose. While the HHV-8 capsid exhibits many structural similarities to the HSV-1 capsid, our reconstruction shows two major differences: its hexons lack the "horn-shaped" VP26 densities bound to the HSV-1 hexon subunits, and the HHV-8 triplexes appear smaller and less elongated than those of HSV-1. These differences are in excellent agreement with our sequence comparisons of HHV-8 and HSV-1 capsid proteins. This gammaherpesvirus capsid structure complements previous structural studies on alpha- and betaherpesviruses in providing an account of structural similarities and differences among capsids representing all human herpesvirus subfamilies.

Capsid↗
PubMed2000

Efficacy of ondansetron for prevention of postoperative nausea and vomiting after outpatient ear surgery under local anesthesia.

OBJECTIVE: To assess the efficacy and safety of intravenous ondansetron (4 mg) for the prevention of nausea and vomiting after middle ear surgery under local anesthesia. SETTING: The study was conducted by Division of Otorhinolaryngology in Prince of Wales Hospital, which is a tertiary referral center and teaching hospital for The Chinese University of Hong Kong. STUDY DESIGN: A double-blind randomized controlled trial. PATIENTS: Fifty-eight Chinese patients undergoing tympanoplasty under local anesthesia from July 1995 to June 1997 were recruited. The mean age of patients was 42.8 years (range 18-71 years). INTERVENTION: Patients were randomly allocated to receive a single dose of intravenous ondansetron (4 mg) (n = 29) or placebo (n = 29) immediately before surgery. MAIN OUTCOME MEASURES: Patients were assessed for severity and frequency of postoperative nausea and vomiting at the 1st, 2nd, 4th, 8th, and 24th hours after middle ear surgery. RESULTS: Female patients showed a higher prevalence of postoperative nausea and vomiting. Twenty-eight percent of the patients experienced postoperative nausea, of whom 14% also experienced vomiting. Although the ondansetron group demonstrated a lower prevalence of postoperative nausea and vomiting (PONV) (24% nausea and 10% vomiting) than the placebo group (31% nausea and 17% vomiting), significant reduction in postoperative vomiting only occurred in the first postoperative hour (p = 0.038). No complications or adverse side effects were found to be associated with the use of ondansetron. CONCLUSIONS: Single-dose ondansetron (4 mg) given intravenously preoperatively significantly reduces postoperative vomiting in patients after tympanoplasty under local anesthesia and causes no adverse effects.

Adolescent↗
PubMed1999

Expression and androgen regulation of C-CAM cell adhesion molecule isoforms in rat dorsal and ventral prostate.

C-CAM is an epithelial cell adhesion molecule with two major splice variants that differ in the length of the cytoplasmic domain. C-CAM1 (long (L)-form) strongly suppresses the tumorigenicity of human prostate carcinoma cells. In contrast, C-CAM2 (short (S)-form) does not exhibit tumor-suppressive activity. In the present study we have investigated the functional significance of L-form and S-form C-CAM in rat prostate by examining their expression and distribution in different prostate lobes and their response to androgen deprivation. RNase protection assays with a probe for both C-CAM isoforms detected high levels of C-CAM messages in the rat dorso-lateral prostate (DLP). L- and S-form proteins, localized by indirect immunofluorescence using isoform-specific antipeptide antibodies, were co-expressed on the apical surface of prostate epithelial cells in normal DLP. Androgen depletion did not significantly change the steady state levels of C-CAM message and protein expression in the DLP, although there was a change in the pattern of protein expression in these lobes. In contrast, C-CAM isoform messages and proteins were undetectable in normal ventral prostate (VP) but increased markedly in this lobe in response to castration, producing isoform ratios similar to those in DLP. These results demonstrate that coordinate expression of C-CAM isoforms is maintained in the VP following androgen depletion and suggest that androgen suppresses C-CAM expression in VP but not in DLP. These results suggest that balanced expression of L- and S-form C-CAM is important for normal prostate growth and differentiation.

Adenosine Triphosphatases↗
PubMed1998

Attenuation of intestinal and cardiovascular anaphylaxis by the salivary gland tripeptide FEG and its D-isomeric analog feG.

The effects of the submandibular gland peptide-T (SGP-T; Thr-Asp-Ile-Phe-Gly-Gly; TDIFEGG), its carboxy-terminal fragment (the tripeptide FEG; Phe-Glu-Gly), and the D-isomeric analog (feG) on intestinal and cardiovascular anaphylactic reactions were studied. The tripeptides, FEG and feG, when administered intravenously or orally to egg albumin-sensitized Hooded Lister or Sprague-Dawley rats 30 min prior to challenge with the antigen, totally prevented the disruption of intestinal motility and the development of anaphylaxis provoked diarrhea and inhibited anaphylactic hypotension by 66%. Submandibular gland peptides participate in the regulation of systemic inflammatory reactions, and the D-amino acid tripeptide, feG, is a potent, orally active anti-anaphylactic agent.

Anaphylaxis↗
PubMed1996

Importance of the Bcl-2 family in cell death regulation.

Bcl-2 was first identified as a novel transcript associated with the t(14;18) chromosomal breakpoint which occurs in most follicular lymphomas. The deregulated expression of bcl-2 was found to contribute to multistep neoplasia through the suppression of cell death, or apoptosis, in transgenic mouse models. Bcl-2 was subsequently shown to be normally expressed in a variety of tissues and to significantly inhibit the induction of apoptosis in many experimental systems. Bcl-2 is now known to be structurally similar to other proteins, in particular within the domains referred to as BH1 and BH2. This multigene family of cell death regulators includes members which enhance rates of apoptosis, including bcl-xs and bax, and those which inhibit apoptosis, including MCL-1 and bcl-xL. Members of the bcl-2 family physically interact with other proteins, including other family members and these interactions appear to modulate their function. The mechanism(s) by which bcl-2 family members regulate cell death remain in large part unknown, although recent evidence suggests that bcl-2 may interfere with cellular signalling events involved in apoptosis induction.

Amino Acid Sequence↗
PubMed1996

Overexpression of Bcl-2 and mutations in p53 and K-ras in resected human non-small cell lung cancers.

We investigated expression of Bcl-2, mutations in p53, and K-ras oncogene in 51 resected human non-small cell lung cancers. The studies were designed to test for the possibility of cooperativity between these oncogenes and p53 in the pathogenesis of lung cancer. An inverse relationship was found between expression of Bcl-2 and mutant p53 by immunohistochemistry (P < 0.01; Fisher exact test), suggesting that either Bcl-2 overexpression or mutations in p53 may fulfill a critical function in the pathogenesis of human non-small cell lung cancers. Tumors that harbored K-ras codon 12 mutations seldom had p53 mutations or overexpressed Bcl-2. Statistical analysis of these data showed that mutations in p53 and K-ras or overexpression of Bcl-2 and mutations in K-ras occurred at a frequency that could be explained only by chance [P > 0.1 in each case (Fisher exact tests)]. This suggests that cooperativity between mutant K-ras and mutant p53 or mutant K-ras and overexpressed Bcl-2 is not a common mechanism in the pathogenesis of human non-small cell lung cancers.

Adenocarcinoma↗
PubMed1995

Evaluation of accuracy and reproducibility of E test for susceptibility testing of Streptococcus pneumoniae to penicillin, cefotaxime, and ceftriaxone.

We evaluated the reproducibility with which technologists perform and interpret the E test (AB Biodisk, North America, Inc., Piscataway, N.J.) for determining the susceptibility of Streptococcus pneumoniae to penicillin, cefotaxime, and ceftriaxone. Four technologists prepared E test assays to test 124 isolates of S. pneumoniae. Each technologist then interpreted the results of the E test blinded to the interpretation of the other technologists. In addition, E test results were compared with the reference method of broth microdilution. Intraobserver and interobserver agreement were assessed by use of the kappa statistic. Interpretation of the E test and broth microdilution results showed substantial to excellent agreement, with kappa values ranging from 0.878 to 0.987. Compared with broth microdilution, no very major errors and only four major errors were made with the E test. Most minor errors with penicillin and ceftriaxone occurred for isolates with intermediate or high-level resistance, whereas for cefotaxime the minor errors were more evenly distributed between susceptible and intermediate resistance and between intermediate and high-level resistance. These results indicate that there is good agreement between technologists for the interpretation of the E test when testing the susceptibility of S. pneumoniae to penicillin, cefotaxime, and ceftriaxone and that the results of the E test agree with those of broth microdilution.

Cefotaxime↗
PubMed1994

Mating in the heterothallic haploid yeast Clavispora opuntiae, with special reference to mating type imbalances in local populations.

Mating was studied in the haploid, heterothallic yeast Clavispora opuntiae to assess the importance of nutritional, genetic, and other factors that may favour mating and recombination. Local populations of this yeast generally exhibit dramatic inequalities in mating type distributions, suggesting that mating is rare in nature even though most isolates mate freely in the laboratory. The absence of assimilable nitrogen is prerequisite to mating competence, presumably by causing G1 arrest. Maximum mating competence is found in cells entering stationary phase in nitrogen-limited media. Unlike the vast majority of mating yeasts, C. opuntiae does not appear to produce diffusible mating factors (sex pheromones), and mating-competent cells do not undergo sexual agglutination. Pairwise cell contact appears to be the only signal that triggers the sexual process in this case. In order to determine if mating type imbalances in nature are caused by reduced fertility of 'consanguine' crosses, meiotic recombination was measured in pairs of strains that varied in their genetic distances as indicated by restriction mapping. That hypothesis was rejected, as recombination efficiency decreased with increasing genetic distance. We conclude that the rarity of mating in local populations is exacerbated by the stringent physical (pairwise cell contact) and nutritional (nitrogen depletion) conditions that will allow mating to proceed. Parallels are drawn with mating patterns observed in Clavispora lusitaniae.

Crosses, Genetic↗
PubMed1993

Utilization review of the use of BACTEC PLUS high-volume blood culture bottles.

The BACTEC PLUS 26 (NR26) (Becton Dickinson, Towson, Md.) high-volume blood culture bottle replaced the less expensive smaller-volume NR6A bottle in our hospital. An audit carried out several months after their introduction revealed that only 17.5% of the NR26 bottles received the required blood volume. Several audits and educational programs were required in order to achieve a compliance rate of > 60%.

Bacteremia↗
PubMed1991

The use of magnetic resonance imaging in neurological practice--a local experience.

From April 1990 to September 1990, 170 magnetic resonance imaging (MRI) examinations of the brain were made with the Siemens 1.5 Tesla machine (the "Magnetom") in the Hong Kong Baptist Hospital. The indications for the investigation on the referral forms and the results were analysed. The MRI was particularly useful in making the diagnosis in 2 cases of multiple sclerosis, one case of an Arnold Chiari malformation, 6 cases of cerebro-vascular accidents, and 2 cases of encephalitis. MRI has replaced computerised tomography as the study of choice for the majority of central nervous system disorders.

Brain↗
PubMed1984

Local cerebral glucose utilization rate following intermittent exposures to 2 atmosphere absolute oxygen.

Previous studies have shown significant increases in regional cerebral metabolic rate for glucose (rCMRgl) in 14 of 28 investigated brain structures in rats exposed to 1-h oxygen at 2 atmosphere absolute (ATA O2). Continuous 4-h exposure to 2 ATA O2 resulted in significant increases only in superior olivary nucleus and inferior colliculus. In the present study, the rCMRgl was autoradiographically measured by the [14C]2-deoxyglucose technique during the last 30 min of 4 intermittent 1-h exposures to either 2 ATA O2 or air at atmospheric pressure, with 3 h of breathing air outside the pressure chamber between each oxygen or air exposure. Statistically significant reductions in rCMRgl of the oxygen-exposed rats were observed in superior olivary nucleus and inferior colliculus, while no changes were observed in 26 other investigated structures. The previously observed increases in rCMRgl in a single 1- or 4-h exposure at 2 ATA O2 were reduced or reversed during the intermittent hyperbaric oxygen exposure. The relation of the observed changes in rCMRgl during single and intermittent hyperbaric oxygen exposures to the extension of tolerance to hyperbaric oxygenation is discussed.

Animals↗
PubMed1983

Immunologic study on nasopharyngeal carcinoma patients: correlation of in vivo and in vitro reactivity to phytohemagglutinin.

The skin response to 5 micrograms of purified phytohemagglutinin (PHA) was studied in 125 subjects, including 32 normal controls, 31 patients with head and neck cancer other than nasopharyngeal carcinoma (NPC), and 62 NPC patients. In vitro lymphocyte transformation to PHA (M form) was tested simultaneously to examine its correlation to the PHA skin test. A positive reaction of skin test was observed 24 hours after injection in 29 (90.6%) of 32 normal controls, 16 (51.6%) of 31 patients with head and neck cancer other than NPC, and 51 (82.3%) of 62 NPC patients respectively. Histological examination of the area of erythema revealed the same as those found in the delayed hypersensitivity with perivascular mononuclear cell infiltration. The PHA skin test was repeated 3 times over a period of 9 weeks in 10 normal controls, and no significant change in their skin reactivity was detected. In vitro reactivity to PHA-M was hyporesponsive in NPC patients than in normal controls in three measurements i.e. net counts of incorporated tritiated thymidine, stimulation index, or differences of square roots of counts between the well with PHA and without PHA. Net counts proved to be the most sensitive criterion to differentiate the lymphocyte response to PHA between NPC and normal controls. It is suggested that the general hyporesponsiveness to PHA stimulation in NPC is due to intrinsic T-cell dysfunction. The suboptimal dose of PHA for lymphocyte transformation in NPC was 2.5 microliters per 1.5 X 10(5) cells. Quantitatively, the correlation between in vivo and in vitro reactivity to PHA was not found in normal controls, yet it proved to have a good correlation in some NPC patients--in stage III r = 0.63, p greater than 0.05; in stage IV r = 0.71, p less than 0.01; in stage V r = 0.95, p less than 0.001. Qualitatively (delta cpm greater than or equal to 20,000; erythema greater than or equal to 20 mm), a correlation was found between in vivo and in vitro reactivity to PHA in 27 (84.4%) of 32 normal controls (p less than 0.001), and 39 (62.9%) of 62 NPC patients (p less than 0.01). It is concluded that if in vitro testing of PHA stimulation can not be done, the PHA skin test can be used as an alternative to screen the T-cell functions of NPC patients.

Adolescent↗