Label-free biosensing with singular-phase-enhanced lateral position shift based on atomically thin plasmonic nanomaterials

Rapid plasmonic biosensing has attracted wide attention in early disease diagnosis and molecular biology research. However, it was still challenging for conventional angle-interrogating plasmonic sensors to obtain higher sensitivity without secondary amplifying labels such as plasmonic nanoparticles. To address this issue, we developed a plasmonic biosensor based on the enhanced lateral position shift by phase singularity. Such singularity presents as a sudden phase retardation at the dark point of reflection from resonating plasmonic substrate, leading to a giant position shift on reflected beam. Herein, for the first time, the atomically thin layer of Ge2Sb2Te5 (GST) on silver nanofilm was demonstrated as a novel phase-response-enhancing plasmonic material. The GST layer was not only precisely engineered to singularize phase change but also served as a protective layer for active silver nanofilm. This new configuration has achieved a record-breaking largest position shift of 439.3 μm measured in calibration experiments with an ultra-high sensitivity of 1.72 × 108 nm RIU-1 (refractive index unit). The detection limit was determined to be 6.97 × 10-7 RIU with a 0.12 μm position resolution. Besides, a large figure of merit (FOM) of 4.54 × 1011 μm (RIU∙°)-1 was evaluated for such position shift interrogation, enabling the labelfree detection of trace amounts of biomolecules. In targeted biosensing experiments, the optimized sensor has successfully detected small cytokine biomarkers (TNF-α and IL-6) with the lowest concentration of 1 × 10-16 M. These two molecules are the key proinflammatory cancer markers in clinical diagnosis, which cannot be directly screened by current clinical techniques. To further validate the selectivity of our sensing systems, we also measured the affinity of integrin binding to arginylglycylaspartic acid (RGD) peptide (a key protein interaction in cell adhesion) with different Mn2+ ion concentrations, ranging from 1 nM to 1 mM.

Species composition of mosquito fauna in Ranau, Sabah, Malaysia

The adult population and species composition of mosquitoes collected in Ranau, Sabah are described. A total of 5956 mosquitoes representing 8 genera and 41 species were collected using human landing catch, indoor and outdoor. Anopheles maculatus was the most common species (15.6%) followed by Culex quinquefasciatus (12.8%), Culex pseudovishnui (12.1%), Anopheles balabacensis (11.1%), Culex vishnui (9.7%), Aedes vexans (9.6%), Culex tritaeniorhyncus (6.6%), Anopheles donaldi (5.6%) and others in very small percentage.

Natural transmission of Plasmodium knowlesi to humans by Anopheles latens in Sarawak, Malaysia

Four species of malaria parasites are known to infect humans. A fifth species, Plasmodium knowlesi, has been reported to infect humans in Malaysian Borneo. Here we report for the first time the incrimination of Anopheles latens as the vector of P. knowlesi among humans and monkeys in Sarawak, Malaysia.

Epidemiology of malaria in Attapeu Province, Lao PDR in relation to entomological parameters

Surveys were conducted in malaria-endemic villages in the southern province of Attapeu, Lao PDR during various seasons over a 3-year period. All-night mosquito landing collections, blood surveys and a case-control study were conducted. Plasmodium falciparum was the predominant species, and slide positivity rates were higher during the transition/dry season compared with the wet season. Anopheles dirus A was found to be the primary vector, and sporozoite rates were highest during the transition/dry season. Anopheles dirus was found to be endophagic and endophilic. Not using insecticide-treated bed nets, houses close to breeding sites and sleeping away from home were risk factors associated with malaria.

The impact of development and malaria control activities on its vectors in the Kinabatangan area of Sabah, East Malaysia

A study was carried out from July 2001 until January 2003 in the Kinabatangan area of Sabah, part of Borneo island, where malaria used to be mesoendemic. Vector surveys determined that Plasmodium falciparum was the predominant species and Anopheles balabacensis the primary vector. Malaria cases have dropped drastically over the years but P. falciparum is still predominant. In the present study, Anopheles donaldi was the predominant species and was positive for sporozoites. Although An. balabacensis was present, none were infective. An. donaldi bite more outdoors than indoors and have a peak biting time from 18:00 to 19:00 h when most people are still out of their homes. An integrated malaria control programme along with area development has helped in the control of malaria and its vector.

Endemic malaria in four villages in Attapeu Province, Lao PDR

A study was conducted in four villages in Attapeu Province, Lao PDR in 2002 to determine malaria endemicity. The study villages were Mixay, Beng Phoukham, Phou Vong and Pier Geo. Mass blood surveys were conducted in May, August, and October. Finger prick blood was collected for thick and thin blood film as well as for dipstick. The slide positivity rate was highest in Phou Hom in October (41.7%). Plasmodium falciparum was the dominant species comprising more than 80% of the cases. As a whole, the distribution of malaria was similar among males and females. Children below 15 years accounted for a large percentage of the cases. The sensitivity of the optimal dipstick was 62.36 and the specificity was 61.7. Microscopy was taken as the gold standard. Anopheles dirus was found to be the main vector and the vectorial capacity correlated well with the cases.

Malaria transmission by Anopheles dirus in Attapeu Province, Lao PDR

A study was carried out in four malaria-endemic villages in Attapeu Province, in the southern region of Lao PDR. All-night human landing collections were carried out in May, August, and October 2002, to determine malaria vectors. At the same time, mass blood surveys were also carried out in the same villages. Anopheles dirus was the predominant species in three of the study villages. Sporozoites were found only in An. drius from Phou Hom. However, in Beng Phoukham, An. dirus was positive for oocysts. The distribution of malaria cases was highest in Phou Hom and this correlated well with the vectorial capacity of An. dirus. The risk for infection from An. dirus was also high, at 0.99.

An undiagnosed phaeochromocytoma of the urinary bladder

Phaeochromocytoma of the urinary bladder is rare. We report a case of a patient with undiagnosed bladder phaeochromocytoma who developed haemodynamic disturbances during routine diagnostic cystoscopy. The diagnosis was only confirmed postoperatively.

The use of vasopressin to treat catecholamine-resistant hypotension after phaeochromocytoma removal

A patient undergoing excision of phaeochromocytoma developed refractory hypotension which was complicated by significant intraoperative blood loss. Cardiovascular support with fluids, blood and noradrenaline failed to reverse the hypotension. Introduction of vasopressin successfully reversed the hypotension. The experience with this case suggests that vasopressin may be a useful adjunct in the treatment of catecholamine-resistant hypotension after phaeochromocytoma excision.

Conjugated polyhydroxybenzene derivatives block tumor necrosis factor-alpha-mediated nuclear factor-kappaB activation and cyclooxygenase-2 gene transcription by targeting IkappaB kinase activity

Because the transcription factor, nuclear factor (NF)-kappaB, plays a key role in cellular inflammatory and immune responses, components of the NF-kappaB-activating signaling pathways are frequently used as targets for anti-inflammatory agents. This study shows that 2-(3',4'-dihydroxyphenyl)-5-hydroxybenzo[b]furan (GF-015) and 2,3-di(3',4'-dihydroxy-transstyryl) pyridine (GF-90), two conjugated polyhydroxybenzene derivatives, inhibited a common step in NF-kappaB activation in human NCI-H292 epithelial cells by preventing tumor necrosis factor (TNF)-alpha- and 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced IkappaB kinase (IKK) complex activation. Both agents inhibited the TNF-alpha- or TPA-induced expression of cyclooxygenase (COX)-2 mRNA and protein, COX-2 promoter activity, and prostaglandin E2 (PGE2) production. Overexpression of wild-type NF-kappaB-inducing kinase, IKKalpha, and IKKbeta led, respectively, to 3.5-, 2.6-, and 2.6-fold increases in COX-2 promoter activity, and these effects were inhibited by both compounds. GF-015 and GF-90 also prevented the TNF-alpha- and TPA-induced activation of IKK and NF-kappaB-specific DNA-protein binding activity. These results suggest that the inhibitory effect of GF-015 and GF-90 on TNF-alpha-induced COX-2 protein expression was caused by suppression of IKK activity and NF-kappaB activation in the COX-2 promoter, resulting in attenuation of COX-2 gene expression and PGE2 production.

Temporal effect of human oviductal cell and its derived embryotrophic factors on mouse embryo development

Mouse embryos at different stages of development were cocultured with human oviduct cells or cultured in the presence of oviduct-derived embryotrophic factor-1, -2, and -3 (ETF-1, -2, and -3) for various amounts of time within the preimplantation period. Cocultures that included the period from 48 to 72 h post-hCG stimulated cell division and increased the cell numbers in the inner cell mass (ICM) of the exposed blastocyst. Exposure of embryos to oviductal cells from 96 to 120 h post-hCG increased the cell number in the trophectoderm (TE), blastocyst size, hatching rate, attachment, and in vitro spreading of the blastocyst. ETF-1 and ETF-2 affected embryos between 48 and 72 h post-hCG by increasing the number of cells in the ICM. In contrast, ETF-3 had a more profound effect on embryos that were exposed from 96 to 120 h post-hCG, where it mostly affected the development of TE cells, leading to higher hatching rate. Human oviductal cells improved mouse embryo development partly by the production of high molecular weight embryotrophic factors. These factors had differential effects on mouse embryo development.

Quantification of transforming growth factor beta1 (TGFbeta1) mRNA expression in mouse preimplantation embryos and determination of TGFbeta receptor (type I and type II) expression in mouse embryos and reproductive tract

We hypothesized that transforming growth factor beta1 (TGFbeta(1)) and its receptors play a role in the interaction between the preimplantation embryo and the reproductive tract. To investigate this hypothesis, TGFbeta 1 mRNA in mouse embryos was quantified by competitive reverse transcription-polymerase chain reaction using an RNA mimic. TGFbeta 1 was first detected in the unfertilized oocyte, disappeared after fertilization and was expressed again at the 2-cell stage (4410 +/- 1330 transcripts/embryo). Its expression increased gradually, peaked at the 8-cell stage (58 600 +/- 17 300 transcripts/embryo) and declined rapidly after the morula stage reaching a concentration of 1520 +/- 546 transcripts/embryo at the blastocyst stage. The mRNA levels of TGFbeta 1 at the 8-cell and morula stages were significantly higher than that at other cell stages (P < 0.05). The expression of TGF receptors in embryos and in the reproductive tract was also investigated. Both TGFbeta(1) type I (ALK-5) and type II TGFbeta receptors were detected in embryos from 1-cell to blastocyst stage by immunohistochemistry. Northern hybridization and immunohistochemistry showed a constant expression of both TGFbeta receptors in the oviduct from day 1 to day 4 of pregnancy, whilst in the uterus there was a marked increase in the expression of TGFbeta type I receptor on day 3. Expression of TGFbeta type II receptor in the uterus remained unaltered throughout the study period. This study has shown that preimplantation mouse embryos produce TGFbeta(1) and that both the embryos and the reproductive tract are responsive to TGFbeta(1) in the preimplantation period.

Intravenous regional anaesthesia using lignocaine and tramadol

INTRODUCTION

This prospective, randomised, double-blind study was designed to assess if the addition of 50 mg tramadol to 30 mL 0.5% lignocaine would improve the efficacy of intravenous regional anaesthesia.

MATERIALS AND METHODS

Fifty-four adult patients undergoing upper limb surgery were randomly allocated to receive either 30 mL 0.5% lignocaine and 1 mL normal saline (group A) or 30 mL 0.5% lignocaine and 50 mg tramadol (group B). They were then assessed for onset of sensory and motor block and the VbAS score for tourniquet pain.

RESULTS

Although more patients in group B had a faster onset of sensory and motor block, this was not significantly different. Patients in group B had a significantly lower VbAS score 30 min after tourniquet inflation and after change over to the distal tourniquet (P < 0.05). There were no complaints of postoperative nausea and vomiting. Two patients in group B developed localised skin urticaria of the forearm which resolved with the release of the tourniquet.

CONCLUSION

There is a positive trend that tramadol might improve the quality of intravenous regional anaesthesia.

The incidence of cytoplasmic fragmentation in mouse embryos in vitro is not affected by inhibition of caspase activity

OBJECTIVE

To investigate the relationship between cytoplasmic fragmentation and caspase activity in the mouse embryo.

DESIGN

Experimental laboratory study.

SETTING

University gynacology unit.

ANIMAL(S)

One-cell zygote of mouse (MF1 x BALB/c).

INTERVENTION(S)

Mouse embryos were treated with caspase inhibitors: benzyloxycarbonyl-Val-Ala-Asp fluoromethylketone (z-VAD-fmk) and benzyloxycarbonyl-Asp-glu-Val-Asp-fluoromethyl ketone (Z-DEVD-fmk).

MAIN OUTCOME MEASURE(S)

Morphological development of the embryo, proportion of fragmented embryos, caspase-3-like activity, DNA breakage, and phosphatidylserine exposure in blastomeres.

RESULT(S)

The proportion of embryo reaching two-cell, three- to four-cell, and morula stage at 48, 72, and 96 hours after hCG administration, respectively, were comparable between the control embryos and those treated with either z-VAD-fmk or z-DEVD-fmk, at three concentrations (10 microM, 50 microM, and 200 microM). Although the inhibitors suppressed the caspase-3-like activity in the embryo fragment before compaction and decreased DNA breakages, there was no statistically significant difference in the percentage of fragmented embryo between the control and those treated with caspase inhibitors. The inhibitors did not affect the incidence of phosphatidylserine exposure in the blastomere of the treated embryos.

CONCLUSION(S)

Cytoplasmic fragmentation in precompaction mouse embryos is not a consequence of caspase-related apoptosis.

A comparative study of gene expression in murine embryos developed in vivo, cultured in vitro, and cocultured with human oviductal cells using messenger ribonucleic acid differential display

The objectives of this study were to compare the mRNA expression patterns in early mouse embryos in different culture conditions by differential display reverse transcription-polymerase chain reaction (DDRT-PCR). Embryos developed in vivo, cultured in vitro, and cocultured with human oviductal epithelial cells were studied at the 2-cell, 4-cell, 8-cell/morula, and blastocyst stages. Messenger RNA profiles were displayed by DDRT-PCR using downstream T11VV (V = A, C, or G) and upstream decamer primers. Total cDNA banding patterns were highly conserved in the three groups studied. Some fragments are unique in different culture conditions. Thirteen out of the 40 selected differentially expressed clones were characterized. The DNA sequence analyses of these clones displayed high sequence homology with cDNA sequences in the mouse expressed sequence tag database. Using semiquantitative RT-PCR, we confirmed differential expression of these DD amplicons in the three groups of embryos. The temporal expression of some of the selected DD amplicons during preimplantation development were studied in the three groups of embryos. In conclusion, DDRT-PCR is an effective tool for contrasting gene expression patterns and characterizing mRNA transcripts in mouse embryo.

A prospective evaluation of surgeon performed sonography as a screening test in blunt abdominal trauma

INTRODUCTION

Sonography has found a role in the evaluation of patients with abdominal injury. However, the accuracy of sonography as performed by non-radiologists remains controversial. This study aims to determine the accuracy of focused abdominal sonography for trauma when performed by surgeons.

MATERIALS AND METHOD

Over a 1-year period, 48 patients with abdominal injury were initially evaluated for free intraperitoneal fluid by sonography. These tests were performed by 2 surgeons who had received instructions and performed a minimum of 30 examinations. Sonographic findings were then compared with other diagnostic modalities including computed tomography (CT) scan, diagnostic peritoneal lavage and exploratory laparotomy.

RESULTS

The sensitivity, specificity, positive predictive value, negative predictive value and accuracy for sonography were found to be 0.86, 0.92, 0.89, 0.90 and 0.89, respectively. Although not specifically sought for, 2 cases of solid organ injury and 1 haemothorax, which were missed in initial examinations and X-rays, were detected on sonography.

CONCLUSION

In conclusion, our initial experience suggests that local surgeons can perform a focused sonographic examination for trauma with acceptable accuracy. Although sonography lacks the sensitivity of diagnostic peritoneal lavage and the accuracy of CT scan, the diagnostic algorithm for abdominal trauma should include sonography as a screening test.

Human oviductal cells reduce the incidence of apoptosis in cocultured mouse embryos

OBJECTIVE

To investigate the effect of human oviductal cell coculture on the incidence of apoptosis in mouse embryos.

DESIGN

Experimental laboratory study.

SETTING

University gynecology unit.

PATIENT(S)

Fallopian tubes were obtained from patients undergoing hysterectomy.

INTERVENTION(S)

Mouse embryos were cocultured with human oviductal cells.

MAIN OUTCOME MEASURE(S)

Blastocyst development, allocation of inner cell mass (ICM) and trophectoderm (TE) in blastocyst, and apoptosis in embryos.

RESULT(S)

Oviductal cells significantly enhanced the blastulation (38%) and hatching rate (22%) of the cocultured zygotes. The corresponding values in medium alone culture were 21% and 9%, respectively. The cocultured embryos also had higher blastomere count at blastocyst stage (P<0. 005). This was due to increase in both the cell count of ICM (P<0. 05) and TE (P<0.001). Coculture reduced the incidence of apoptosis in the cultured morula and blastocyst from 38% and 48% to 16% (P<0. 001) and 27% (P<0.05), respectively. The number of apoptotic blastomeres per morula (1.5 +/- 0.6; P<0.005) and blastocyst (2.3 +/- 0.7; P<0.005) after coculture was also significantly lower than that of the corresponding control (morula, 2.1 +/- 0.8; blastocyst, 3.5 +/- 1.1).

CONCLUSION(S)

Human oviductal cells improved mouse embryo development partly by decreasing the incidence of apoptosis.

Changes in prostaglandin and nitric oxide levels in the hyperdynamic circulation following liver resection

BACKGROUND AND AIMS

Significant changes in hepatic haemodynamics occur after major hepatectomy, but the pathogenesis of this phenomenon is unclear. This study investigates the serum profile of prostaglandin and nitric oxide in the hepatic and systemic circulation before and after hepatectomy and the temporal relationship of these to changes in the hepatic blood flow.

METHODS

Blood samples were collected from the internal jugular, portal and hepatic veins of six Yorkshire pigs (17-25 kg) before, immediately after and 48 h after partial hepatectomy.

RESULTS

Serum levels of prostacyclin I2 (PGI2) and prostaglandin E2 (PGE2) from the systemic circulation, the portal circulation and from the hepatic veins were found to differ considerably even before hepatectomy. After the hepatectomy was performed, there was a significant rise in PGI2 levels in the systemic circulation (P=0.027). Hepatic blood flow and cardiac output were measured before hepatectomy, 24 and 48 h after hepatectomy in another six pigs. A significant increase in hepatic blood flow (P=0.029) occurred after the hepatectomy and this was accompanied by a concomitant increase in the cardiac output (P=0.042). The increase in PGI2 concentration in the systemic circulation after hepatectomy appears to accompany the development of hyperdynamic hepatic and systemic circulations. No significant change was found in circulating PGE2 levels in the systemic, portal and hepatic veins at the three collection intervals (i.e. pre, post and 48 h after hepatectomy). The PGE2 levels in the hepatic vein, however, were significantly higher from than in the portal vein (P=0.028). No significant changes were observed in the level of nitric oxide.

CONCLUSION

This study demonstrates an increase in the total hepatic blood flow after hepatectomy together with a threefold increase in prostacyclin in the systemic circulation. The liver was identified as the main source of circulatory prostaglandin.

Transurethral surgery and the adductor spasm

INTRODUCTION

Transurethral surgery has become the dominant treatment for bladder and prostatic tumours. Regional anaesthesia is the favoured anaesthetic technique but adductor spasm leading to bladder wall perforation and increased morbidity is not uncommon. This review seeks to outline the cause, risk factors predisposing to this complication and the various techniques that have been adopted to eradicate it.

METHODS

Literature search was performed from PubMed (1965 onwards). All studies related to obturator nerve stimulation or adductor spasm in transurethral surgery were short-listed.

RESULTS

Various methods have been attempted. These ranged from local blockade of the obturator nerve, periprostatic and subvesical lignocaine infiltration, changing the site of the inactive electrode, reduction of the electrocoagulation voltage and general anaesthesia with muscle relaxants.

CONCLUSIONS

Hitherto, local blockade of the obturator nerve, either by the direct method or "3-in-1" method is the most effective in preventing this complication. With the aid of a nerve stimulator, greater accuracy and use of smaller volumes of local anaesthetic will improve the safety of this block.

A non-invasive isotope dilution technique for quantifying hepatic blood flow using radiolabelled red blood cells

Clinically significant changes in hepatic haemodynamics accompany the development of portal hypertension, hepatocellular carcinoma, liver metastases and liver cirrhoses, and after major liver resection. Hepatic blood flow parameters, such as hepatic arterial flow (HAF), hepatic portal flow (HPF), total hepatic blood flow (THBF) and hepatic perfusion index (HPI), are useful adjuncts to the diagnosis of liver pathology, the evaluation of disease progress and prognostication. Here, we describe a non-invasive method that combines the measurement of these parameters in a single study in real time. Red blood cells from eight pigs were labelled with 99Tc(m) using an in-vitro method and re-injected into the pigs. Data acquisition over the heart, lungs, liver and kidneys was started immediately and a blood sample was obtained 15 min post-injection. Hepatic arterial flow was determined from the ratio of the maximum gradients between the integrated time-activity curve of the left ventricle and the first-pass time-activity curve of the liver before the peak of the kidneys time-activity curve. The hepatic perfusion index was determined by comparing the slope of the liver time-activity curve before and after the kidney peak. Hepatic portal flow was determined from the hepatic arterial flow and the hepatic perfusion index, and total hepatic blood flow was determined as the sum of arterial and portal flow. The results were compared against those obtained from a clearance method using 99Tc(m)-DISIDA. The average hepatic perfusion index was 0.38, and the average hepatic arterial flow and hepatic portal flow were 168.3 +/- 52.9 and 274.6 +/- 60.1 ml x min(-1) respectively. The average total hepatic blood flow was 442.8 +/- 53.5 ml x min(-1), while the total hepatic flow determined by 99Tc(m)-DISIDA clearance was 419.7 +/- 62.6 ml x min(-1). No significant difference in total hepatic blood flow was found between the two methods. The results of this study show that it is possible to obtain all hepatic haemodynamics data in a single study using a non-invasive method.

Influence of respiration and portal pressure on transabdominal duplex Doppler ultrasound measurement of portal blood flow: a porcine model for experimental studies

Transabdominal duplex Doppler ultrasonography (TDDU) is commonly used for measuring hepatic blood flow (HBF) in clinical practice. Flow velocity and the cross-sectional area (CSA) of vessels are obtained separately and used to compute blood flow. Respiration and changes in portal pressure are known to cause variations in the CSA of the portal vein, but the impact of these parameters on TDDU measurement of portal blood flow is unclear. Eight Yorkshire pigs (20.7-25.1 kg) were used for the study. TDDU determination of portal blood flow was carried out using CSA of the portal vein obtained at inspiration (maximal) and at expiration (minimal) for computation, and the differences obtained were compared. Determination of HBF was carried out simultaneously on the same animals using diisopropyliminodiacetic acid (DISIDA) clearance. A physiological increase in portal pressure was then created by 50% hepatectomy and TDDU measurement similarly carried out on the second postoperative day. Computing portal blood flow in the intact liver using maximal and minimal CSA gave rise to a mean difference of 7.0 ml kg(-1) min(-1) (P < 0.001). A significant correlation was obtained between HBF and portal flow computed from maximal CSA (Pearson's correlation = 0.85, P < 0.033). The respiratory index of the portal vein (maximal CSA/minimal CSA) decreased from 1.5 to 1.2 after hepatectomy, which also caused a 90% increase in portal pressure. Respiration and portal pressure thus significantly impact on TDDU determination of HBF, and in this porcine model, computation using maximal CS more accurately reflects HBF.

Bile duct injuries during laparoscopic cholecystectomy: a collective experience of four teaching hospitals and results of repair

BACKGROUND

Laparoscopic cholecystectomy has been performed in Singapore since 1990 and, up until the end of 1997, a total of 4445 procedures had been performed in the four major teaching hospitals. Although bile duct injuries were thought to have increased following the introduction of laparoscopic cholecystectomy, there have been no reviews done on the incidence of these injuries in the Singapore context.

METHODS

The present retrospective review aimed to audit the rate of bile duct injuries in the four major teaching hospitals in Singapore and to document the results of management of these injuries.

RESULTS

Of the 4445 procedures performed, there were 19 (0.43%) cases of bile duct injuries. These involved the common hepatic duct (n = 8), common bile duct (n = 10), and the right hepatic duct (n = 1). The underlying gall bladder pathology included non-inflamed gall bladders (n = 10), acute cholecystitis (n = 4), Mirrizzi's syndrome (n = 3) and mucocele of the gall bladder (n = 2). Transection of the duct accounted for the majority of the injuries. Eleven bile duct injuries were identified at the time of operation. These were primarily repaired over a T tube (n = 4) or by a bilio-enteric bypass (n = 7). The remainder were diagnosed at a median of 7 days (range: 1-556 days) after surgery with a presentation of jaundice or pain. These were repaired by bilio-enteric anastomosis (n = 7) and closure over a T tube (n = 1). Three patients developed strictures subsequently, two following bilio-enteric repair after delayed diagnosis and one following immediate primary repair over a T tube. One patient developed intrahepatic stones and required a left lateral segmentectomy.

CONCLUSIONS

The experience of a 0.43% bile duct injury rate is comparable to the best results from most large series in the West. Inflammation at Calot's triangle is an important associated factor for injury. Early recognition and prompt repair affords good results, and hepaticojejunostomy is recommended as the repair of choice.

Use of EMLA cream or alfentanil for analgesia during ophthalmic nerve blocks

This prospective double-blind study compared the effectiveness of EMLA with alfentanil and placebo in reducing the overall pain during ophthalmic nerve blocks. Seventy-five patients scheduled for cataract surgery were divided into three groups. Patients in the EMLA group had EMLA cream applied over skin areas corresponding to injection sites for retrobulbar and facial nerve blocks one hour before the nerve blocks, and placebo intravenous normal-saline injection 2 minutes before the first nerve block. The alfentanil group had placebo cream applied and intravenous alfentanil 10 micrograms.kg-1 while patients in the placebo group received placebo cream and intravenous normal-saline at similar time intervals prior to the nerve blocks. Patients then received facial nerve blocks and retrobulbar block by the same surgeon. Pain scores by patients and independent observers were significantly lower in the EMLA and alfentanil groups compared to placebo (P < 0.005) with no significant difference between the EMLA and alfentanil groups.

Splenic actinomycosis

We report a rare case of abdominal actinomycosis occurring in the spleen and review the literature on abdominal actinomycosis.

Separation of bovine serum albumin and its monoclonal antibody from their immunocomplexes by sodium dodecyl sulfate-capillary gel electrophoresis and its application in capillary electrophoresis-based immunoassay

A non-competitive immunoassay was performed by sodium dodecyl sulfate-capillary gel electrophoresis with UV detection using bovine serum albumin (BSA) and monoclonal anti-BSA. BSA, anti-BSA and their immunocomplexes were well resolved under non-denaturing conditions. A linear calibration curve was obtained and can be used for the quantification of anti-BSA. The limit of detection of anti-BSA was 0.1 microM under the present conditions. Compared with capillary zone electrophoresis, we believed that this method has the potential to be used as a more general format for performing capillary electrophoresis-based immunoassay of medium- and large-sized analytes.

Use of capillary electrophoresis-based competitive immunoassay for a large molecule

A systematic study on the optimization of capillary electrophoresis-based immunoassay (CEIA) was performed using bovine serum albumin (BSA) and monoclonal anti-BSA. The immunocomplex could not be resolved from free BSA or anti-BSA with UV detection. When fluorescein isothiocyanate-labeled BSA (FITC-BSA) was used as tracer, the free and bound FITC-BSA were well separated giving definite peaks with laser induced fluorescence detection. The factors affecting the separation of the free and bound FITC-BSA, including voltage, pH and ionic strength of the running buffer, were systematically analyzed. Competitive CEIAs were demonstrated in uncoated and coated capillaries with whole or Fab fragment of the antibody. The coefficient of variation for the quantification of BSA in coated capillary was less than that in uncoated capillary. This study demonstrated that competitive CEIA could be applied to quantify high-molecular-mass protein in biological fluids.

Relationship of thyroid blood flow to reproductive events in normal Chinese females

The purpose of this study was to investigate the blood flow characteristics in the superior thyroid artery (STA) in normal females of prepubertal, reproductive, and postmenopausal age. The study was performed in 29 prepubertal girls, 27 females of reproductive age, and 26 postmenopausal women. The peak systolic velocity (PSV) and the pulsatility index (PI) of the STA were measured repeatedly during one menstrual cycle in females of reproductive age, and measured once in each prepubertal and postmenopausal subject. Different waveforms were observed in females of prepubertal, reproductive, and postmenopausal age. The PSV of the STA increased progressively in females from prepubertal to postmenopausal phases. The PI of the STA in all of the prepubertal girls was lower than that of adult females in different phases of the menstrual cycle. In adult females, the PI in the follicular phase was significantly higher than those in the ovulatory and luteal phases. In all of the postmenopausal women, the PI was comparable to that in older prepubertal subjects and in adult females during the ovulatory and luteal phases. The results suggest that oestrogen may affect thyroid blood flow during the normal menstrual cycle. Growth and progressive change of arterial structure are suggested to affect the thyroid blood flow in prepubertal and postmenopausal states.

Preventable trauma deaths in Singapore

BACKGROUND

This study was undertaken to determine the incidence of preventable trauma death at a non-designated trauma centre in Singapore.

METHODS

A retrospective audit was carried out on all trauma deaths that occurred between January 1993 and December 1994 at the National University Hospital, Singapore. Of the 138 deaths, 38.4% (53/138) of patients were dead on arrival and were omitted from the study. Data from the remaining 85 deaths were summarized and presented before a multidisciplinary review board and injuries were scored according to the Abbreviated Injury Scale (AIS).

RESULTS

Except for one patient, all deaths had an AIS score of 16 or greater. Sixty-one per cent (52/85) of deaths were the result of severe head injuries, and the rest had severe injuries in more than one body region. Following the guidelines of the Trauma Research and Education Foundation of San Diego, the incidence of 'not preventable', 'potentially preventable' and 'frankly preventable' deaths were 77.6, 15.3 and 7.1%, respectively. The most common errors in management were caused by delays in inter-departmental transfer (25.9%) and missed initial diagnosis (16.5%). After assessment by the Coroner's Office, autopsies were carried out in 60% of the cases and yielded information that altered the assessment of preventable deaths, particularly in the group with multiple injuries.

CONCLUSIONS

The present study concludes that the preventable death rates in the National University Hospital are comparable to those in non-trauma designated centres elsewhere. There can only be a decrease in the preventable death rate if an improved system of pre-hospital trauma care, improved interdisciplinary communication, closer supervision of the initial attending physicians and stricter protocols on clinical monitoring are established.

Abdominal surgery in human immunodeficiency virus (HIV) infected patients--early local experience

The prevalence of human immunodeficiency virus (HIV) infection is increasing in Singapore. The surgical experience, however, remains limited. A retrospective review of 13 HIV-positive patients requiring abdominal surgery within Singapore was done. There were 4 females and 9 males with age ranging from 21 to 44 years. Operations included appendicectomy, colectomy, splenectomy, intestinal bypass, gastrostomy and exploratory laparotomy. Pathologic findings directly related to HIV infection were found in two-fifths (5 out of 13) of these patients. A low CD4+ count or signs of full-blown acquired immunodeficiency syndrome (AIDS) were not associated with a higher likelihood of HIV-related pathology; neither did it preclude a successful outcome. There were 2 early postoperative deaths, both with HIV-related pathology. Five of our patients who survived their abdominal surgery died on follow-up with a median survival of 17 months. In patients with typical surgical problems, e.g. appendicitis and torsion of the ovary, early surgery allows for rapid recovery similar to normal surgical patients. Care of these patients is best provided by surgeons with experience and interest in this condition together with infectious diseases physicians. Even palliative surgery offers a respite from acute and often severe problems and improves the quality of life significantly. Two patients with AIDS presented with sepsis and diffuse abdominal tenderness. Subsequent laparotomy revealed only primary bacterial peritonitis. For patients with AIDS and non-localizing abdominal signs, alternative non-invasive diagnostic modalities such as computed tomographic (CT) scan should be considered.

Ambulatory anorectal surgery--is it feasible locally?

Currently, anorectal procedures are done in an inpatient setting in most local hospitals. This study examines the feasibility of performing these procedures in an outpatient setting. Patients (age range 16 to 65 years) with anorectal complaints requiring surgery were randomized into 2 groups of 40 patients each. Procedures performed included haemorrhoidectomy, fistulotomy, lateral sphincterectomy, excision of rectal polyps and examination under anaesthesia. The first group was managed in the conventional inpatient setting with regional anaesthesia. The second group was done on an ambulatory basis with local anal block. Intravenous and oral ketorolac was used for postoperative pain control and patients were discharged about 4 hours postoperatively. No complications were noted in the second group while the first group had 2 cases of acute urine retention requiring temporary catheterisation and 2 cases of significant bleeding requiring hospitalisation. Pain and satisfaction scores for both groups were similar. Anorectal surgery can be performed in an outpatient setting locally with safety and efficacy. The cost savings can be significant.

Partial purification of embryotrophic factors from human oviductal cells

Embryotrophic factors from human oviductal cells were partially purified by liquid chromatographic methods. The conditioned medium from human oviductal cell culture was fractionated successively by concanavalin A (Con-A) affinity chromatography, ion-exchange chromatography and gel filtration. The presence of the embryotrophic activity in the eluates was determined by the stimulatory effects on the development of mouse embryos in vitro. The fraction that did not bind to the lectin Con-A possessed no embryotrophic activity. Ion-exchange chromatography separated the glycoproteins that bound to Con-A into five fractions. Three of them significantly enhanced blastulation as well as conceptus formation. Gel filtration further separated these embryotrophic fractions into five fractions. Three of them with molecular weights of 154 +/- 1, 164 +/- 0.2 and 207 +/- 0.3 kDa significantly stimulated blastulation of mouse embryos. The results of this study demonstrated that several embryotrophic factors with different biochemical properties contributed to the embryotrophic effect of the human oviductal cell/mouse embryo co-culture system.

Alteration of thyroid blood flow during the normal menstrual cycle in healthy Chinese women

The purpose of this study was to investigate the relationship between thyroid activity and the menstrual cycle by measuring the Doppler parameters of the superior thyroid arteries in women of reproductive age. The study was performed in 27 healthy Chinese women aged between 19 and 28 y for one menstrual cycle, and 25 age-matched healthy Chinese men for 3 weeks for comparison. In women, the peak systolic velocity increased from the follicular phase to the luteal phase, and the pulsatility index decreased from the follicular phase to the ovulatory phase and increased slightly in the luteal phase. In men, alterations in the pattern of thyroid blood flow were not observed; however, the average values of Doppler parameters during the study period in women were similar to those in men. The gender difference in the pattern of flow characteristics in the superior thyroid artery suggests effects of estrogen on thyroid function.

Expression of differential nitric oxide synthase isoforms in human normal gastric mucosa and gastric cancer tissue

The present study investigated the expression and distribution of three isoforms of nitric oxide synthase (NOS) in different anatomical regions of the human stomach and in gastric neoplastic tissues by immunohistochemistry using specific antibodies. Intracellular localization of individual isoenzymes of NOS was detected in normal gastric mucosa. Gastric cancer tissues had a marked reduction of all three NOS isoforms expression. The expression of the endothelial NOS, neuronal NOS and inducible NOS in the tumor tissue was significantly lower than in normal gastric mucosa (P = 0.01, P = 0.02, P < 0.01, respectively). In the tumor tissue the expression of inducible NOS was significantly lower than the expression of both constitutive forms of NOS (P < 0.01). There was a tendency to higher expression of both constitutive forms of NOS in earlier stages T2 of the tumor compared to advanced T4 tumor. In contrast, the expression of inducible NOS was higher than in the advanced T4 tumor than in the earlier stages T2 of the tumor. The mapping of the expression of endothelial NOS, neuronal NOS and inducible NOS in human stomach showed higher expression of NOS isoforms in the distal third than in the proximal third of the stomach (P = 0.03, P = 0.04, P = 0.01, respectively). We conclude that there is greater expression of NOS in the stomach corpus and in antrum than in the proximal third of the normal human stomach mirroring the anatomical predilection of common pathological changes in this part of the human stomach. Furthermore, there was loss of the expression of individual isoenzymes in gastric neoplasms.

Transfection of rat brain cells by electroporation

Genetic intervention is a powerful means for answering basic biological questions about molecular events taking place in brain cells underlying complex behaviors. Traditional transfection method has proved difficult to apply to neuronal cells. We therefore described an alternative procedure for introducing DNA into cultured rat brain cells by electroporation. The various parameters involving the voltage, capacitance and electroporation buffer are investigated. We found that this transfection procedure is simple, reproducible and applicable to rat brain cells in vitro.

Effects of physical barriers in prevention of adhesions: an incisional hernia model in rats

BACKGROUND

Adhesion formation between viscera and mesh is almost inevitable following incisional hernia repair with prosthetic mesh. Such adhesions may lead to intestinal obstruction and enterocutaneous fistulae formation and make further laparotomies extremely difficult. Sodium carboxymethylcellulose (SCMC) and Interceed TC7 (oxidized regenerated cellulose) as physical barriers have been shown to be effective in reducing postoperative adhesions.

MATERIALS AND METHODS

To evaluate the effects of SCMC and Interceed TC7, we used an incisional hernia model in rats. A ventral abdominal defect (15 x 25 mm) was created in each of 36 male rats which were then divided into three equal groups. In Group I (control) the defect was repaired with polypropylene mesh (PPM) only; in Group II the defect was repaired after a layer of Interceed TC7 was laid over the viscera with Interceed TC7-covered PPM; in Group III the defect was repaired after a layer of SCMC was laid over the viscera with SCMC-coated PPM. Six of the animals from each group were sacrificed at Postoperative Day 7 and the adhesions were scored. The remaining 6 were sacrificed at Day 30 and histological evaluation was made in addition to the adhesion score.

RESULTS

Animals in the SCMC-treated group developed significantly less adhesions (P = 0.0002) compared with control and Interceed TC7-treated groups. However, histological analysis revealed poor fibroblast proliferation with impaired wound healing in the SCMC group.

CONCLUSION

SCMC prevented adhesion formation but seriously impaired wound healing, and Interceed TC7 was ineffective in preventing adhesion in this model.

Coculture with homologous oviductal cells improved the implantation of human embryos--a prospective randomized control trial

PURPOSE

The efficacy of homologous oviductal cell coculture on the success of a human in vitro fertilization program was investigated in a prospective randomized control clinical trial.

METHODS AND RESULTS

One hundred eighty-one couples were randomized into the control and the coculture groups. Pronuclear-stage zygotes were either cultured in Earles' balanced salt solution supplemented with 15% preovulatory serum (control) or cultured with human oviductal cells (coculture) for 24 hr before embryo transfer. There was no difference in the age of the patients, indication for treatment, number of oocyte retrieved or fertilized, or number of embryo replaced between the two groups. The pregnancy rates per transfer for the control and the coculture group were 12.8 and 19.3%, respectively. The number of viable fetus was significantly higher (P < 0.01, chi-square test) in the coculture group (25/264) than in the control group (8/262). The coculture group also showed a higher multiple pregnancy rate, lower abortion rate, and more spare embryos suitable for cryopreservation.

Anopheles donaldi incriminated as a vector of periodic Brugia malayi in Grik, Perak, Malaysia

Studies were carried out to observe the species composition of mosquitos and to determine the vectors responsible for the transmission of filariasis in Grik, Perak, Malaysia. A total of 2,155 mosquitos belonging to 7 genera and 30 species were collected. Anopheles donaldi comprised 24.1% of the collection. Twelve out of 519 An. donaldi were infected with L3 larvae of Brugia malayi. The peak biting time was around 23.00-24.00 hours. The infective bites per month ranged from 0 to 6.3.

Differential expression of adenosine A1 receptors in colorectal cancer and related mucosa

Adenosine A1 receptors (A1R) are known to inhibit while the A2 receptors (A2R) stimulate the G-protein cAMP second messenger system and may play a role in cell growth and carcinogenesis. Using a quantitative reverse transcription-polymerase chain reaction (RT-PCR) method, mRNA for A1R and A2R was measured in human colorectal adenocarcinomas and individual peritumoural colon tissues. There was differential expression of the mRNA for A1R with tumour tissues having significantly higher amounts compared to peritumoural normal tissues. The mRNA for A2R was not found to be differentially expressed. The increase in the inhibitory A1 receptor in tumour tissues may be in response to increased adenosine release from the hypoxic cells found in malignant tumour tissues, thus indicating a possible role for the adenosine A1 receptor in carcinogenesis.

Nitric oxide synthase activity and expression in human colorectal cancer

The present study investigated the activity and cellular localization of individual isoenzymes of nitric oxide synthase (NOS) using immunohistochemistry and the [3H]citrulline assay in normal colorectal epithelia and neoplastic tissue. Intracellular localization of isoenzymes of NOS was detectable by immunohistochemistry in normal epithelial cells. Colorectal adenocarcinomas had a marked reduction of both Inducible NOS (iNOS) and constitutive NOS (cNOS) expression. Expression of iNOS was completely absent in tumour cells (P < 0.0001), while cNOS was reduced in 66% and absent in 34% of tumours studied when compared with controls (P < 0.0001). NOS activity using the [3H]citrulline assay was detectable in normal epithelium and was found to be reduced in tumours (P < 0.001). In addition, colonic adenomas had reduced INOS but not cNOS expression when compared with controls (P < 0.003 and P = 0.39 respectively). We conclude that NOS is present and active within the epithelium of the normal colon, with localization of the individual isoenzymes. Furthermore, there was loss of activity and expression of individual isoenzymes in colonic neoplasms.

Nitric oxide and cancer

The possibility that the overall process of carcinogenesis may be linked to the deficiency of nitric oxide in a biological cell is examined. A hypothetical model of how this might operate to produce subtle changes in a cell resulting in and/or facilitating carcinogenesis is suggested.

Role of oral sodium phosphate and its effectiveness in large bowel preparation for out-patient colonoscopy

The aim of our study was to determine the tolerance and efficacy of oral sodium phosphate compared with polyethylene glycol electrolyte (PEG) solution on out-patient colonoscopy. Seventy-nine patients (35 male, 44 female) for elective out-patient colonoscopy were randomized to receive either PEG (GoLYTELY) solution or oral sodium phosphate (Fleet PhosphoSoda) before the procedure. Patients subsequently completed a questionnaire to assess tolerance to either regimen. The endoscopists, who were blinded to the type of bowel preparation, assessed the results in terms of residual faecal content and percentage of bowel wall visualized. Sixty-seven per cent (26) of 39 patients found Phospho-Soda easy to complete, compared with 53% (21) of 40 patients with PEG (P = 0.06). There was no statistical significance between the two groups in terms of symptomatology. Colonoscopic assessment of the Phospho-Soda group showed better cleansing compared to the PEG group at all levels of the colon (P = 0.02-0.002). Phospho-Soda is just as well tolerated as a standard PEG regimen and provides better cleansing of the bowel for colonoscopy.