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Biomedical subjects

P Chong

Publications and source records attributed to P Chong.

At least 19 recordsLinked to original sources
PubMed2006

Hernias are the most common cause of strangulation in patients presenting with small bowel obstruction.

BACKGROUND: Small bowel obstruction (SBO) is a leading cause of admission to surgical emergency units. Strangulation is associated with a 10-fold increase in mortality. The aim of the present study was to identify the most frequent causes of strangulation in patients presenting with small bowel obstruction. METHODS: A prospective study was conducted of all patients presenting with SBO in one teaching hospital between 2003 and 2004. RESULTS: One hundred and sixty-one patients with symptoms and signs of small bowel obstruction were admitted. Eighty-three were confirmed with contrast studies. The male:female ratio was 1:1.6. The aetiology of obstruction was adhesions in 97 patients (60.2%), hernia in 29 (18%), malignancy in 17 (10.6%) and miscellaneous causes in 18 (11.2%). Operative procedures were performed on 74 patients (46%), 31 of them (42%) with adhesions, 25 (34%) with hernias and 18 (24%) due to other causes. Strangulated bowel occurred in 15 patients (9.3%); 12 had hernias whilst three had adhesions (P < 0.0001). Of the strangulated hernias, ten were femoral, one was inguinal and one was paraumbilical. There were seven deaths; three occurred in patients declared unfit for surgery, while four occurred post-operatively - two had strangulated bowel, the other two had advanced cancer. CONCLUSION: Whilst adhesions are the most common cause of small bowel obstruction, hernias remain the most frequent cause of strangulation in patients presenting with this condition.

Aged↗
PubMed2005

Association of malignant disease with critical leg ischaemia.

BACKGROUND: The aim of the study was to determine the prevalence of malignant disease in patients with critical leg ischaemia (CLI). METHODS: : Data for all patients with CLI presenting to a tertiary vascular unit over an 18-month interval were collected prospectively. Patients with clinical, laboratory or radiological features suggestive of malignancy were evaluated further. RESULTS: Of 192 patients admitted with CLI, 22 (11.5 per cent) were found to have an associated malignancy; ten had lung cancer. Fifteen were anaemic on presentation. The prevalence of occult malignancy in patients with acute leg ischaemia was 16 per cent (ten of 62) compared with 9.2 per cent (12 of 130) in those with chronic CLI. Eleven of 22 of patients with CLI and malignancy died within 6 months, compared with 35 (20.6 per cent) of 170 patients with no evidence of malignancy. CONCLUSION: A high prevalence of occult cancer was found in patients presenting with CLI; this was associated with a significantly increased mortality rate at 6 months.

Aged↗
PubMed2005

A randomized study of early nasogastric versus nasojejunal feeding in severe acute pancreatitis.

BACKGROUND: After 50 yr in which nasoenteric feeding was considered contraindicated in acute pancreatitis (AP), several clinical studies have shown that early nasojejunal (NJ) feeding can be achieved in most patients. A pilot study of early nasogastric (NG) feeding in patients with objectively graded severe AP proved that this approach was also feasible. A randomized study comparing NG versus NJ feeding has been performed. METHODS: A total of 50 consecutive patients with objectively graded severe AP were randomized to receive either NG or NJ feeding via a fine bore feeding tube. The end points were markers of the acute phase response APACHE II scores and C-reactive protein (CRP) measurements, and pain patterns by visual analogue score (VAS) and analgesic requirements. Complications were monitored and comparisons made of both total hospital and intensive-care stays. RESULTS: A total of 27 patients were randomized to NG feeding and 23 to NJ. One of those in the NJ group had a false diagnosis, thereby reducing the number to 22. Demographics were similar between the groups and no significant differences were found between the groups in APACHE II score, CRP measurement, VAS, or analgesic requirement. Clinical differences between the two groups were not significant. Overall mortality was 24.5% with five deaths in the NG group and seven in the NJ group. CONCLUSIONS: The simpler, cheaper, and more easily used NG feeding is as good as NJ feeding in patients with objectively graded severe AP. This appears to be a useful and practical therapeutic approach to enteral feeding in the early management of patients with severe AP.

APACHE↗
PubMed2001

The emergency medicine department system: a study of the effects of computerization on the quality of medical records.

A template based computerized medical record system known as the Emergency Medicine Department System (EMDS) was installed in the emergency department of the National University Hospital, Singapore, replacing handwritten records. A study was carried out to show how the implementation of the EMDS improved the quality of medical records. A retrospective review of old manual records and the ones generated by the EMDS was done by means of a scoring system. The raw scores represent the amount of information captured. The calculated means of scores were then used to compare the records. It was found that EMDS improves the quantity of data capture over the old records in all sections compared. This was seen regardless of the experience of the user. The use of a non-structured generic template results in less data captured compared with a structured symptom-specific template. The design of questions has a great influence in that a double-choice question captures more data than single-choice questions. Building in 'locking' or enforcement mechanisms in the EMDS also helped achieve almost full capture of critical information, such as examination time.

Chest Pain↗
PubMed2000

Antibodies to phosphatidylethanolamine and phosphatidylserine are associated with increased natural killer cell activity in non-male factor infertility patients.

Antiphospholipid antibodies (APA) have been identified in patients with recurrent pregnancy loss and IVF failure. Of these, antiphosphatidylethanolamine (aPE) and antiphosphatidylserine (aPS) may have special significance. A link between increased natural killer cell activity (NKa+) and trophoblast cell apoptosis has also been reported. This study was undertaken to determine how the APA profile was associated with peripheral NK cell activity. We evaluated 197 female IVF candidates for APA and NKa. Eighty-nine patients (45%) were APA+ and of these, 51 (57%) were aPE/aPS+. Fifty-four patients (27%) had increased NK cell activity. Some 51% of APA+ and 78% of aPE/aPS+ patients had increased NK cell activity compared with 8% and 13% when APA and aPE/aPS tested negative respectively (P: < 0.0001). Non-male factor infertility patients were APA+ and NKa+ in 57% and 34% of cases respectively, compared with 19% and 13% if a pure male factor was present. Some 88% of aPE/aPS+, non-male factor patients had increased NK cell activity, compared with 12% who tested aPE/aPS negative (P: < 0.0001) and 25% of aPE/aPS+, isolated male factor patients (P: < 0.0001). These findings establish a direct relationship between APA (specifically aPE/aPS) and increased peripheral NK cell activity among non-male factor infertility patients. It is possible that APA do not directly cause reproductive failure but rather function as markers or intermediaries for an underlying, abnormal activation of cellular immunity.

Adult↗
PubMed1999

Safety and immunogenicity of a live recombinant canarypox virus expressing HIV type 1 gp120 MN MN tm/gag/protease LAI (ALVAC-HIV, vCP205) followed by a p24E-V3 MN synthetic peptide (CLTB-36) administered in healthy volunteers at low risk for HIV infection. AGIS Group and L'Agence Nationale de Recherches sur Le Sida.

A live recombinant canarypox vector expressing HIV-1 gpl20 MN tm/gag/protease LAI (ALVAC-HIV, vCP205) alone or boosted by a p24E-V3 MN synthetic peptide (CLTB-36) was tested in healthy volunteers at low risk for HIV infection for their safety and immunogenicity. Both antigens were well tolerated. ALVAC-HIV (vCP205) induced low levels of neutralizing antibodies against HIV-1 MN in 33% of the volunteers. None of them had detectable neutralizing antibodies against a nonsyncytium-inducing HIV-1 clade B primary isolate (Bx08). After the fourth injection of vCP205, CTL activity was detected in 33% of the volunteers and was directed against Env, Gag, and Pol. This activity was mediated by both CD4+ and CD8+ lymphocytes. On the other hand, the CLTB-36 peptide was poorly immunogenic and induced no neutralizing antibodies or CTLs. Although the ALVAC-HIV (vCP205) and CLTB-36 prime-boost regimen was not optimal, further studies with ALVAC-HIV (vCP205) are warranted because of its clear induction of a cellular immune response and utility as a priming agent for other subunit antigens such as envelope glycoproteins, pseudoparticles, or new peptides.

AIDS Vaccines↗
PubMed1998

Proteolytic processing of rubella virus nonstructural proteins.

The genomic RNA of rubella virus contains two long open reading frames (ORF), a 5'-proximal ORF that codes for the nonstructural proteins and a 3'-proximal ORF that encodes the structural proteins. The cDNA encoding the nonstructural protein ORF of the wild-type M33 strain of rubella virus has been obtained and sequenced. Comparison between the nonstructural proteins of the M33 and Therien strains of rubella virus revealed a 98% homology in nucleotide sequence and 98.1% in deduced amino acid sequence. To examine the processing of rubella virus nonstructural protein, the complete nonstructural protein ORF was expressed in BHK cells using a pSFV expression vector. Three nonstructural protein products (p200, p150, and p90) with molecular weights of 200, 150, and 90 kDa were identified using antisera raised against synthetic peptides corresponding to regions of the nonstructural proteins. p200 is the polyprotein precursor, while p150 and p90 are the cleavage products. Site-directed mutagenesis of the Cys-1151 residue (one of the catalytic dyad residues of the viral protease) and of the Gly-1300 residue (the viral protease cleavage site) abrogated protease activity and p200 precursor cleavage, respectively. Coexpression of mutant constructs in BHK cells indicated that rubella virus protease can function both in cis and in trans.

Animals↗
PubMed1998

The use of combined heparin/aspirin and immunoglobulin G therapy in the treatment of in vitro fertilization patients with antithyroid antibodies.

PROBLEM: To compare the effect of heparin/aspirin therapy alone vs. heparin/aspirin in combination with intravenous immuno-globulin (IVIg) immunotherapy on in vitro fertilization (IVF) outcome of patients who test positive for antithyroid antibodies (ATAs). METHOD OF STUDY: Eighty-two women younger than 40 years of age whose infertility was related exclusively to female causes were evaluated. All tested positive for organ-specific antithyroid antibodies (antimicrosomal and/or antithyroglobulin antibodies), but negative for antiphospholipid antibodies. Thirty-seven of these women (group A) received H/A alone, whereas 45 (group B) received heparin/aspirin in combination with IVIg. RESULTS: Ten (27%) of women in group A and 23 (51%) of women in group B achieved live births after completion of a single IVF/embryo transfer cycle (P = 0.027). CONCLUSION: We conclude that IVIg therapy significantly improves IVF success rates in ATA+ women.

Adult↗
PubMed1998

A rational basis for the use of combined heparin/aspirin and IVIG immunotherapy in the treatment of recurrent IVF failure associated with antiphospholipid antibodies.

PROBLEMS: 1) Does the administration of heparin and aspirin (H/A) in combination with intravenous immunoglobulin G (IVIG) improve in vitro fertilization (IVF) implantation and birth rates in patients with recurrent IVF failure? 2) Is the effect of such treatment related to the antiphospholipid antibody (APA) status of the patients concerned? METHOD OF STUDY: Subjects consisted of 89 women younger than 36 years of age whose infertility was a result of causes other than male infertility and who had experienced four or more failed IVF/embryo transfer procedures. Fifty-two women were APA+ (group A), and 37 were APA- (group B). All patients, regardless of their APA status, received H/A (5000 U sq bid), aspirin (81 mg po qd) from the inception of menotropin therapy along with IVIG (20 g) through a single infusion 3 to 10 days before egg retrieval. RESULTS: Twenty-two (42%) of group A and 7 (19%) of group B patients achieved live births (P = 0.020). CONCLUSIONS: IVF outcome is significantly improved when H/A and IVIG are administered to APA+ women with repeat IVF failures. APA- women do not seem to benefit from such treatment.

Adult↗
PubMed1998

The selective use of heparin/aspirin therapy, alone or in combination with intravenous immunoglobulin G, in the management of antiphospholipid antibody-positive women undergoing in vitro fertilization.

PROBLEM: The effect of mini-dose heparin/aspirin (H/A) alone vs. combined intravenous immunoglobulin G (IVIg) and H/A on in vitro fertilization (IVF) birthrates in women who test seropositive for antiphospholipid antibodies (APA+) was evaluated, as was the question of whether outcome is influenced by the gammaglobulin isotype(s) or the phospholipid (PL) epitope(s) to which the APAs are directed. METHOD OF STUDY: A case-control study was conducted in three phases, spanning a 4-year period, in a multicenter clinical research environment. Six hundred eighty-seven APA+ women, who were younger than 40 years and who each, completed up to three consecutive IVF/embryo transfer cycles within a 12-month period, were given either H/A alone or H/A in combination with IVIg. Birthrates relative to the type of immunotherapy (i.e., H/A alone and H/A with IVIg) and APA profile were the main outcome measurements. RESULTS: In phase I, 687 women who tested APA+ to one or more PL epitopes underwent two or fewer IVF attempts for a total of 1050 IVF cycles. Four hundred seventy-seven (46%) births occurred in 923 IVF cycles in which H/A alone was administered. Twenty-two (17%) births occurred after 127 IVF cycles in which H/A was not administered. In phase II, 322 of 687 women tested positive for a single APA subtype. These subjects underwent up to two consecutive IVF attempts for a total of 521 IVF cycles while receiving H/A alone. The birthrate was significantly lower for women whose APAs were directed toward phosphatidylethanolamine (PE) or phosphatidylserine (PS) involving IgG or IgM isotypes than for women who had any other APA (17% vs. 43%). In phase III, 121 women who did not achieve live births after two consecutive IVF attempts in which H/A alone was administered received IVIg in combination with H/A during their third consecutive IVF cycle. The birth rate was 41% after these IVF cycles when anti-PS or anti-PE involving IgG or IgM isotypes were present, as compared with 17% when H/A alone was administered. The IVF outcome did not improve when IVIg was administered in association with any other single APA. CONCLUSIONS: The treatment of APA+ women with H/A alone improves IVF birthrates. This benefit is selective in that it does not apply in cases in which IgG- or IgM-related APAs are directed against PE or PS. In such cases, the addition of IVIg significantly improves the outcome.

Abortion, Habitual↗
PubMed1998

Correlation between beta 2-glycoprotein antibodies and antiphospholipid antibodies in patients with reproductive failure.

PROBLEM: Antiphospholipid antibodies (APAs) are important in the etiology of reproductive failure. Studies have shown that binding proteins are necessary for the detection of APAs. One of these, beta 2-glycoprotein, has been shown to be necessary for detection of anticardiolipin antibodies. It is felt that some APAs may be directed to the binding protein itself, or to a combination of the binding protein and phospholipid. METHOD OF STUDY: In this study, a comparison of APAs vs. anti beta 2-glycoprotein antibodies was performed on the sera of 123 women younger than 40 years of age with a history of reproductive failure. Antibodies to six phospholipid epitopes, cardiolipin, phosphatidyle-thanolamine, phosphatidylserine, phosphatidylinositol, phosphatidic acid, phosphatidylglycerol, and phosphatidylserine, were measured. RESULTS: Of the 123 women tested, 33 had one or more positive immunoglobulin (Ig)G antibodies to phospholipids, of which 9 were to cardiolipin. However, only 1 of 123 women had IgG antibodies to beta 2-glycoprotein and she was APA negative. Thirty-eight of 123 women had one or more IgM antibodies to phospholipids, with none directed to cardiolipin IgM. In contrast, only 8 of the 123 women had IgM antibodies to beta 2-glycoprotein. Five of the eight patients had IgM APA; 4 of 5 had IgM antibodies to PE, 1 to PI. CONCLUSIONS: There is no correlation between beta 2-glycoprotein antibodies and APA status in this population. To date, our most sensitive test for detecting phospholipid autoimmune-mediated in vitro fertilization failure still appears to be the ELISA assay for APA.

Adult↗
PubMed1998

A 20-kilodalton N-terminal fragment of the D15 protein contains a protective epitope(s) against Haemophilus influenzae type a and type b.

A conserved 80-kDa minor outer membrane protein, D15, of Haemophilus influenzae has been shown to be a protective antigen in laboratory animals against H. influenzae type a (Hia) or type b (Hib) infection. To localize the protective B-cell epitope(s) within the D15 protein and to further explore the possibility of using synthetic peptides as vaccine antigens, a 20-kDa N-terminal fragment of D15 protein (truncated D15 [tD15]) was expressed as a fusion protein with glutathione S-transferase in Escherichia coli. The tD15 moiety was cleaved from glutathione S-transferase by using thrombin and purified to homogeneity. The purified soluble tD15 appeared to contain immunodominant protective epitope(s) against Hia and Hib, since rabbit antisera directed against tD15 were capable of protecting infant rats from Hia or Hib bacteremia. The ease of purification of soluble tD15, therefore, makes it a better candidate antigen than the full-length recombinant D15 which is produced as inclusion bodies in E. coli. Furthermore, both the purified tD15 fragment and a mixture of tD15-derived peptides spanning amino acid residues 93 to 209 of the mature D15 protein were capable of inhibiting the protection against Hib conferred on infant rats by rabbit anti-tD15 antiserum, indicating that the protective epitopes of D15 may not be conformational. However, the administration of pooled rabbit immune sera raised against the same panel of peptides failed to protect infant rats from Hib infection.

Amino Acid Sequence↗
PubMed1998

Cloning and expression of the Moraxella catarrhalis lactoferrin receptor genes.

The lactoferrin receptor genes from two strains of Moraxella catarrhalis have been cloned and sequenced. The lfr genes are arranged as lbpB followed by lbpA, a gene arrangement found in lactoferrin and transferrin receptor operons from several bacterial species. In addition, a third open reading frame, orf3, is located one nucleotide downstream of lbpA. The deduced lactoferrin binding protein A (LbpA) sequences from the two strains were found to be 99% identical, the LbpB sequences were 92% identical, and the ORF3 proteins were 98% identical. The lbpB gene was PCR amplified and sequenced from a third strain of M. catarrhalis, and the encoded protein was found to be 77% identical and 84% similar to the other LbpB proteins. Recombinant LbpA and LbpB proteins were expressed from Escherichia coli, and antisera raised to the purified proteins were used to assess antigenic conservation in a panel of M. catarrhalis strains. The recombinant proteins were tested for the ability to bind human lactoferrin following gel electrophoresis and electroblotting, and rLbpB, but not rLbpA, was found to bind lactoferrin. Bactericidal antibody activity was measured, and while the anti-rLbpA antiserum was not bactericidal, the anti-rLbpB antisera were found to be weakly bactericidal. Thus, LbpB may have potential as a vaccine candidate.

Amino Acid Sequence↗
PubMed1997

Effect of lipid modification on the physicochemical, structural, antigenic and immunoprotective properties of Haemophilus influenzae outer membrane protein P6.

The outer membrane lipoprotein, P6 of Haemophilus influenzae was studied to determine the importance of the native palmitoyl moiety on its physicochemical and immunological properties. A recombinant P6 (rP6) molecule devoid of lipidation signal sequence was expressed in Escherichia coli and its properties were compared to those of the palmitylated protein purified from H. influenzae. The isoelectric point of rP6 was more acidic than that of the native protein and also exhibited less secondary structure than P6 as judged by circular dichroism. However, both forms of P6 induced identical P6-specific antibody titers in guinea pigs when Freund's adjuvant was used. These antisera reacted with a panel of overlapping P6 peptides in a comparable manner and in addition, rabbit antisera raised against the P6 peptides reacted equally well with P6 and rP6. Furthermore, all human convalescent sera tested exhibited similar anti-P6 and anti-rP6 antibody titers. However, rP6 was less immunogenic than P6 when administered either without adjuvant or in alum and when tested in competitive inhibition studies with anti-P6 antibodies, was a less effective inhibitor than native P6, suggesting a diminution in some of the antigenic activity of rP6. In spite of these differences, rP6 was capable of eliciting a protective antibody response against live H. influenzae type b challenge in a modified infant rat model of bacteremia. These findings demonstrate that the non-fatty acylated rP6 could possibily be substituted for native P6 in a vaccine against H. influenzae.

Amino Acid Sequence↗
PubMed1997

Chemical synthesis of Haemophilus influenzae glycopeptide conjugates.

A simple procedure for conjugating synthetic fragments of the capsular polysaccharide of Haemophilus influenzae type b, poly-3-beta-D-ribose-(1,1)-D-ribitol-5-phosphate (sPRP) to linear peptides is described. The procedure consists of (i) reacting the amino group of amino-heptyl sPRP with m-maleimidobenzoyl-N-hydroxysuccinimide (MBS) in phosphate buffer, pH 7.5; (ii) selectively coupling the MBS-modified sPRP to the sulfhydryl group of the cysteine residue of peptides containing functional T-helper cell epitope(s). The glycopeptide conjugates were purified by gel filtration chromatography, biochemically characterized, and elicited protective level of anti-PRP antibody responses in rabbits.

Amino Acid Sequence↗
PubMed1997

The major outer membrane protein, CD, extracted from Moraxella (Branhamella) catarrhalis is a potential vaccine antigen that induces bactericidal antibodies.

The major outer membrane protein of Moraxella (Branhamella) catarrhalis, CD, was detergent-extracted from the bacterial cell wall and purified to homogeneity in high yields by a simple process. The purified protein appeared to exhibit immunogenic properties similar to those of native CD exposed on the surface of the bacterium. Antibodies to CD raised in mice specifically bound to intact B. catarrhalis, as determined by flow cytometry analysis. The IgG subclass distributions of anti-CD antibodies in sera from mice immunized with purified CD or with B. catarrhalis were also similar. CD was found to be antigenically conserved among a panel of B. catarrhalis isolates, as demonstrated by the consistent reactivities of mouse anti-CD antisera with a common 60 kDa protein on immunoblots. Furthermore, convalescent sera collected from patients with otitis media due to B. catarrhalis infection were found to be reactive with the CD protein by immunoblotting. Finally, the purified protein induced antibodies in guinea pigs and mice that exhibited in vitro bactericidal activity against the pathogen. Therefore, the native CD outer membrane protein represents a potentially useful antigen for inclusion in a vaccine against B. catarrhalis.

Amino Acid Sequence↗