Search PubMed⌕ Search

Biomedical subjects

S C Chan

Publications and source records attributed to S C Chan.

At least 55 records · Page 3Linked to original sources
PubMed1999

Surgical wound infection.

OBJECTIVE: To review the risk factors for surgical wound infection; the use of prophylactic antibiotics in the prevention of wound infection; and the benefits of wound surveillance programmes to reduce the rate of surgical wound infection. DATA SOURCES: Medline literature search and review of published work on surgical wound infection, and the references cited in them. STUDY SELECTION: Critical studies containing supporting evidence were selected. DATA EXTRACTION: Data were extracted independently by multiple observers. DATA SYNTHESIS: Factors that affect the susceptibility of a wound to infection include a pre-existing illness, the duration of the operative procedure, wound contamination, three or more diagnoses at the time of discharge, and abdominal operations. Antibiotic prophylaxis can decrease postoperative morbidity, shorten hospital stay, and reduce overall costs attributable to infection; the choice of antibiotic depends on the wound class. Wound surveillance can also decrease wound infection rates. CONCLUSION: Surgical wound infections are common and consume a considerable portion of health care finances. A reduction in the infection rate to a minimal level, however, can be achieved by the judicious use of antibiotic prophylaxis and the use of an organised system of wound surveillance and reporting.

Journal Article↗
PubMed1998

Antioxidant properties of butein isolated from Dalbergia odorifera.

The antioxidant properties of butein, isolated from Dalbergia odorifera T. Chen, were investigated in this study. Butein inhibited iron-induced lipid peroxidation in rat brain homogenate in a concentration-dependent manner with an IC50, 3.3+/-0.4 microM. It was as potent as alpha-tocopherol in reducing the stable free radical diphenyl-2-picrylhydrazyl (DPPH) with an IC0.200, 9.2+/-1.8 microM. It also inhibited the activity of xanthine oxidase with an IC50, 5.9+/-0.3 microM. Besides, butein scavenged the peroxyl radical derived from 2,2-azobis(2-amidinopropane) dihydrochloride (AAPH) in aqueous phase, but not that from 2,2-azobis(2, 4-dimethylvaleronitrile) (AMVN) in hexane. Furthermore, butein inhibited copper-catalyzed oxidation of human low-density lipoprotein (LDL), as measured by conjugated dienes and thiobarbituric acid-reactive substance (TBARS) formations, and electrophoretic mobility in a concentration-dependent manner. Spectral analysis revealed that butein was a chelator of ferrous and copper ions. It is proposed that butein serves as a powerful antioxidant against lipid and LDL peroxidation by its versatile free radical scavenging actions and metal ion chelation.

Animals↗
PubMed1998

Presynaptic inhibition of GABAergic inputs to rat substantia nigra pars reticulata neurones by a cannabinoid agonist.

Whole-cell patch-clamp recordings were made from substantia nigra pars reticulata (SNR) neurones in rat midbrain slices to investigate the electrophysiological effects of cannabinoids. The cannabinoid receptor agonist WIN 55212-2 (10 microM) significantly reduced intranigrally evoked and spontaneous inhibitory post-synaptic currents (IPSCs) which were mediated by GABA(A) receptors. The postsynaptic current induced by bath application of GABA was not affected by the presence of WIN 55212-2. The actions of WIN 55212-2 were not mimicked by the inactive enantiomer WIN 55212-3. WIN 55212-2 also hyperpolarized the membrane of SNR neurones in a tetrodotoxin/0-Ca2+-insensitive manner. These data suggest that cannabinoids modulate the activity of SNR neurones by presynaptic inhibition of GABA inputs. They may also exert a direct post-synaptic inhibition on these neurones.

Animals↗
PubMed1998

Microscopic observations of the different morphological changes caused by anti-bacterial peptides on Klebsiella pneumoniae and HL-60 leukemia cells.

Natural anti-bacterial peptides cecropin B (CB) and its analogs cecropin B-1 (CB-1), cecropin B-2 (CB-2) and cecropin B-3 (CB-3) were prepared. The different characteristics of these peptides, with amphipathic/hydrophobic alpha-helices for CB, amphipathic/amphipathic alpha-helices for CB-1/CB-2, and hydrophobic/hydrophobic alpha-helices for CB-3, were used to study the morphological changes in the bacterial cell, Klebsiella pneumoniae and the leukemia cancer cell, HL-60, by scanning and transmission electron microscopies. The natural and analog peptides have comparable secondary structures as shown by circular dichroism measurements. This indicates that the potency of the peptides on cell membranes is dependent of the helical characteristics rather than the helical strength. The microscopic results show that the morphological changes of the cells treated with CB are distinguishably different from those treated with CB-1/CB-2, which are designed to have enhanced anti-cancer properties by having an extra amphipathic alpha-helix. The morphological differences may be due to their different modes of action on the cell membranes resulting in the different potencies with lower lethal concentration and higher concentration of 50% inhibition (IC50) of CB on bacterium and cancer cell, respectively, as compared with CB-1/:CB-2 (Chen et al. 1997. Biochim. Biophys. Acta 1336, 171-179). In contrast, CB-3 has little effect on either the bacterium or the cancer cell. These results provide microscopic evidence that different killing pathways are involved with the peptides.

Amino Acid Sequence↗
PubMed1998

Three new flavonoids and antiallergic, anti-inflammatory constituents from the heartwood of Dalbergia odorifera.

Three new flavonoids, (3R)-4'-methoxy-2',3,7-trihydroxyisoflavanone (11), 7-methoxy-3,3',4',6-tetrahydroxyflavone (18), and 2',7-dihydroxy-4',5'-dimethoxyisoflavone (22), were isolated from the heartwood of Dalbergia odorifera T. Chen. (Leguminosae), together with twenty-two known compounds, (S)-4-methoxydalbergione (1), cearoin (2), medicarpin (3), formononetin (4), sativanone (5), 3-hydroxy-9-methoxy-coumestan (6), meliotocarpan A (7), isoliquiritigenin (8), stevein (9), liquiritigenin (10), 3',4',7-trihydroxyflavanone (12), butein (13), 3'-hydroxymelanettin (14), koparin (15), bowdichione (16), fisetin (17), melanettin (19), sulfuretin (20), 3'-hydroxydaidzein (21), 3'-O-methylviolanone (23), xenognosin B (24), and dalbergin (25). These flavonoids were evaluated in antiallergic and anti-inflammatory tests. The results showed that (S)-4-methoxydalbergione (1) and cearoin (2) exhibited antiallergic activity while (S)-4-methoxydalbergione (1), cearoin (2), butein (13), koparin (15), bowdichione (16), 3'-O-methylviolanone (23), and xenognosin B (24) showed significant anti-inflammatory activity.

Animals↗
PubMed1997

Effects of the anti-bacterial peptide cecropin B and its analogs, cecropins B-1 and B-2, on liposomes, bacteria, and cancer cells.

Custom designed analogs of the natural anti-bacterial peptide cecropin B (CB) have been synthesized; cecropin B-1 (CB-1) was constructed by replacing the C-terminal segment (residues 26 to 35) with the N-terminal sequence of CB (positions 1 to 10 which include five lysine residues). The second analog, CB-2, is identical to CB-1 except for the insertion of a Gly-Pro residue pair between Pro-24 and Ala-25. These peptides were used to investigate their anti-liposome, anti-bacterial and anti-cancer activities. The strength of anti-liposome activity is reduced two- to three-fold when the analogs are used instead of natural CB based on DL50 analysis. Similarly, the potency of these analogs on certain bacteria is about two- to four-fold lower than those of CB based on LC measurements. In contrast, on leukemia cancer cells, the potency of CB-1 and CB-2 is about two- to three-fold greater than that of natural CB based on IC50 measurements. All CB, CB-1 and CB-2 peptides have comparable helix contents according to CD measurements. These results indicate that the designed cationic lytic peptides, having extra cationic residues, are less effective in breaking liposomes and killing bacteria but more effective in lysing cancer cells. The possible interpretations for these observations are discussed.

Amino Acid Sequence↗
PubMed1997

Subtalar arthrodesis with interposition tricortical iliac crest graft for late pain and deformity after calcaneus fracture.

We are reporting our experience using tricortical interposition iliac crest grafting in the management of late pain and deformity after calcaneus fracture. Ten patients underwent this procedure, which was performed by the senior author. All but one were followed up with a questionnaire, physical examination, and repeat x-rays. The technique failed in one severely osteoporotic individual because of the graft sinking into the calcaneus. The experience led to two technique modifications that were evaluated in this study.

Arthrodesis↗
PubMed1997

Effects of supplemental fat and protein source on ruminal fermentation and nutrient flow to the duodenum in dairy cows.

Four lactating Holstein cows, fitted with ruminal and T-type duodenal cannulas, were used in a 4 x 4 Latin square design for four periods (14 d each). Treatments were 1) medium fat and low quality protein, 2) medium fat and high quality protein, 3) high fat and low quality protein, and 4) high fat and high quality protein. Fat was supplemented by addition of 2.5% prilled fatty acids to high fat diets. The low quality diets contained corn gluten meal and 0.47% Lys, and the high quality diets contained a mixture of fish, blood, and soybean meals and 0.77% Lys. The percentage of Met was similar for all diets (mean, 0.28%). Diets contained 35 to 38% steam-flaked sorghum and 32% chopped alfalfa hay. Dietary CP averaged 18%, and all diets were high in RUP (44% of CP). Yields of milk, milk protein, and SNF were increased by added fat and by high quality protein. Ruminal NH3 and butyrate were increased by supplemental fat. Cows fed high quality protein had increased ruminal VFA, propionate, butyrate, and valerate, but decreased ratios of acetate to propionate. Essential AA concentrations in coccygeal plasma and arteriovenous differences across the mammary gland were higher for Lys and lower for Leu in cows fed high quality protein than in those fed low quality protein.

Animal Feed↗
PubMed1997

Effects of ruminally inert fat and evaporative cooling on dairy cows in hot environmental temperatures.

Under hot summer conditions of Tucson, Arizona, 24 Holstein cows (mean = 80 d of lactation) were assigned for 56 d to four treatments in a randomized block design with a 2 x 2 factorial arrangement of treatments. Factors were 1) medium [4.6% of dry matter (DM)] versus high (7.4% of DM) amounts of dietary fat and 2) corral shade only versus shade equipped with evaporative cooling. The high fat diet contained 3% prilled fatty acids. The efficiency of the conversion of feed to milk tended to be better for cows fed prilled fat than for cows fed medium dietary fat, but other lactation measurements were unaffected. Cows with access to evaporative cooling had greater milk yields than did cows with access to shade only. Prilled fatty acids did not depress the percentage of milk protein, but reduced short- and medium-chain fatty acids (C6:0 to C14:0) in milk fat and increased palmitic acid. Digestibilities of DM, organic matter, crude protein, acid detergent fiber, neutral detergent fiber, and starch were unaffected by amount of fat or by cooling method, but prilled fatty acids tended to decrease apparent digestibility of fatty acids. No differences were observed among treatments in respiration rates or rectal temperatures. When rectal temperatures were determined, cows were crowded, which probably negated detection of an effect of evaporative cooling. Evaporative cooling increased milk yield of cows in hot weather, but the addition of 3% fatty acids did not increase yield, and no interactions were observed.

Animals↗
PubMed1997

Comparison of barley and sorghum grain processed at different densities for lactating dairy cows.

To vary ruminally degradable starch, sorghum grain was dry-rolled or steam-flaked to different densities and compared with dry-rolled barley in total mixed diets fed to 40 lactating cows (111 d of lactation) assigned to five dietary treatments. Diets contained (percentage of dry matter) 35% alfalfa hay, 4.1% cottonseed hulls, 10% whole cottonseed, 2% fish meal, 4% soybean meal, and 4.9% of a molasses, mineral, and vitamin supplement. Treatments were 40% sorghum grain either dry-rolled or steam-processed at flake densities of 437, 360, and 283 g/L. A fifth diet containing 42% dry-rolled barley was fed. Cows were blocked according to pretreatment (14 d) milk yield and received experimental diets for 56 d. Increasing ruminal starch degradability by including steam-flaked sorghum grain or barley in the diet did not increase milk yield or milk protein percentage and yield, as was shown in eight previous studies. Steam-flaked sorghum or dry-rolled barley in the diet decreased dry matter intake, resulting in a 10 to 19% higher efficiency of conversion of feed dry matter to milk than that for dry-rolled sorghum. Milk urea N was decreased, and milk casein yield tended to be increased, by steam-flaking sorghum at the moderate density compared with dry-rolling or fine flaking. Dietary protein was more efficiently converted to milk protein and casein from flaked sorghum and dry-rolled barley than from dry-rolled sorghum. In this study, increasing ruminal starch degradability resulted in higher feed efficiency and lower feed intakes, bu optimal flake densities for steam-processed sorghum gain to maximize milk and milk protein yield were not clarified.

Animal Feed↗
PubMed1997

A Malaysian Well Person's Clinic--review of patients seen between April and December 1995.

The Well Man & Well Woman's Clinic in Ipoh Hospital provides screening for coronary risk factors and early detection of cancer. This retrospective review of 1095 patients screened between April and December 1995 showed 48% had one or more coronary risk factors--1 risk (29%), 2 risks (14%), 3 or more risks (5%). Modifiable risks included hypertension (10%), obesity (9%), diabetes mellitus (8%) and smoking (7%). Sixteen abnormal Papanicolaou smears and six cancers (three cervical, two breast and one ovarian) were detected. Public response was good. There is a need for clinics offering comprehensive screening in Malaysian primary health care.

Adult↗
PubMed1997

Active resuscitation in Malaysian district hospitals--is it adequate?

Adequacy of active resuscitation in collapsed inpatients aged 12 and above (excluding those with terminal illness) were studied in 6 Malaysian district hospitals for 3 months starting 1/1/93. Results showed 59.5% (25 out of 42 inpatients) were inadequately resuscitated measured by: failure of nurses to initiate resuscitation (24%), duration of resuscitation less than 30 minutes (42%) and incompletely equipped emergency trolleys (44%). Questionnaires revealed lack of knowledge and training in cardiopulmonary resuscitation in medical staff. Regular cardiopulmonary resuscitation courses, regular spot checks on emergency trolleys and management protocols on active resuscitation are recommended. Each hospital should design its own criteria for adequacy.

Adolescent↗
PubMed1997

Audit of diabetes in Perak outpatient departments.

Adequacy of diabetic management in 5 Perak outpatient departments was studied in April 1996. Two hundred diabetic patients' records were analysed. All doctors and 100 patients answered questionnaires on diabetes. Fifty five percent of doctors had adequate knowledge. Patients' knowledge varied between centres (13% to 80% adequacy). Most records had insufficient data to determine adequacy of early detection. Centres with screeners had adequate weight and blood pressure measurement. Overall control and monitoring of diabetes were inadequate. Referral of complications were delayed in 2 centres. Refresher courses for doctors, patient health education, protocols, screeners and physician visits are recommended.

Ambulatory Care Facilities↗
PubMed1997

Real time ultrasound diagnosis of non-vaterian duodenal adenoma--a brief case report.

Non-vaterian duodenal adenomas are rare lesions, usually present with bleeding and abdominal pain. Sonography is often the first imaging procedure in patients with vague upper abdominal complaints, unsuspected duodenal pathology may be encountered. It is now widely accepted as the first choice for the investigation of abdominal masses. Oral water load is recognised as a good procedure for the detection of a bowel-related mass during sonographic examination. In our case, we used the real-time ultrasound with water ingestion to detect the location of the duodenal lesion and its relationship to the neighboring structure. This report demonstrates that conventional real-time ultrasound is still a simple method to diagnose duodenal lesions.

Adenoma↗
PubMed1997

Small bowel stenosis from blunt abdominal trauma.

A patient with a segmental stricture of the small bowel resulting from blunt abdominal trauma is reported. Symptoms and signs developed as vague abdominal distension with chronic, incomplete small bowel obstruction four weeks after the accident. A small bowel barium examination provided the important images for preoperative evaluation.

Abdominal Injuries↗
PubMed1997

Clinics in diagnostic imaging (31). Adrenal neuroblastoma.

A 3-year-old girl presented with epigastric pain and physical examination showed a hard right upper quadrant mass. Urine VMA and HVA were found to be raised. CT scan showed a large mass arising from the right adrenal gland, with necrotic areas and ring calcification There was midline extension. The diagnosis of neuroblastoma was confirmed by bone marrow aspiration biopsy. As the patient had inoperable stage IV neuroblastoma, she was treated with multi-drug chemotherapy. Follow-up CT scan showed excellent response to the chemotherapy, and the tumour was successfully resected. Harvesting of autologous peripheral bone marrow stem cells, megatherapy with Melphalan, and marrow rescue with the stem cells were effective. The child has been well for three years to date. The clinical and imaging features of neuroblastoma, particularly the role of imaging in staging, are emphasised.

Adrenal Gland Neoplasms↗
PubMed1996

Isolation of anti-leukemia compounds from Citrus reticulata.

In vitro effects of medicinal plant extracts from the pericarpium of Citrus reticulata (cv Jiao Gan) (PCRJ) on the growth and differentiation of a recently characterized murine myeloid leukemic cell clone WEHI 3B (JCS) were investigated. Extracts of PCRJ not only inhibited the proliferation of JCS cells in a dose dependent manner, but also induced differentiation of JCS cells into macrophages and granulocytes. Morphological differentiation of PCRJ treated JCS cells was associated with an increase in phagocytic activity of the cells. Furthermore, both in vitro clonogenicity and in vivo growth of PCRJ treated JCS leukemic cells in syngeneic BALB/c mice were significantly reduced. The survival rate of mice receiving PCRJ treated JCS tumour cells was also increased. Using 1H-NMR, 13C-NMR, and GC/MS, two active components isolated from PCRJ were identified as nobiletin and tangeretin.

Animals↗