Biomedical subjects

R Sim

Publications and source records attributed to R Sim.

At least 19 recordsLinked to original sources

PubMed2003

Delayed diagnosis of foreign body aspiration in children.

Foreign body aspiration in children is common and usually presents with an initial episode of choking with subsequent respiratory symptoms. There may be cough, wheeze, or stridor, with decreased or abnormal breath sounds on examination. However, it can mimic other illnesses and cause difficulty in diagnosis. Radiological investigations may help to confirm aspiration but should not be used to exclude it. Three cases are presented of foreign body aspiration with a delay in diagnosis ranging from days to weeks. It is believed that delay could have been avoided with a more careful approach to the history and more appropriate use of investigations. These cases demonstrate that children with a history of choking and subsequent symptoms should be referred for bronchoscopy.

Bronchi↗

PubMed2001

Non-radioactive digoxigenin DNA labeling and immunologic detection of HSV PCR products.

BACKGROUND: Herpes simplex virus (HSV) is a common cause of human skin and mucous membrane infections, and also causes sporadic meningoencephalitis. As a new method for rapid HSV diagnostics, polymerase chain reaction (PCR) has been introduced in clinical laboratories. Radioactive labeling of DNA probes has become a common practice in experimental laboratories. To avoid radioactive labeling of HSV oligonucleotide probes or PCR products, non-radioactive compounds, which are easily detected by enzyme or immunoassay techniques, are introduced. OBJECTIVES: The aim of our study was (1) to introduce non-radioactive labeling of HSV DNA probe by digoxigenin-labeled dUTP; (2) to establish a rapid and reliable laboratory method for rapid HSV diagnostics; (3) to compare the PCR method with the standard virology techniques, such as cell culture virus isolation and HSV direct fluorescent antibody test (DFA). STUDY DESIGN: We have tested the efficiency of PCR method and non-radioactive labeling of HSV DNA probe for detection of HSV from 30 clinical specimens (skin and mucous membrane swabs). HSV was detected in the specimens by standard virology techniques and PCR. Replicated HSV DNA was non-radioactively labeled by random incorporation of digoxigenin-labeled deoxyuridine triphosphate (DIG-dUTP), and the hybrids were detected by the antibody conjugates and the appropriate enzyme-mediated staining reaction (DIG DNA labeling and detection kit non-radioactive, Boehringer Mannheim GmbH). RESULTS: Non-radioactive labeling of hybridization DNA probes with digoxigenin-dUTP was obtained. HSV DNA was successfully multiplied and detected in the HSV-infected cell culture supernatant; however, it was not detected in the clinical specimen supernatant or sediment. HSV DNA was detected by direct PCR method in non-centrifugated clinical specimens. CONCLUSIONS: The PCR method could be successfully used for diagnoses of HSV infections. Since the sensitivity of this method is partly limited by the virus quantity in the specimen, we recommend cultivating the virus in the cell culture at least 24 h prior to PCR. The use of non-radioactive labeling of hybridization DNA probes, such as random primed DNA labeling with digoxigenin-dUTP, has proven both sensitive and specific, and more appropriate for diagnostic purposes than radioactive DNA labeling to be used until standardized commercial tests appear.

Culture Media↗

PubMed2000

Beta(beta)3-adrenergic receptors in human pancreatic islet and duodenal somatostatin neuroendocrine cells.

BACKGROUND: We previously localized beta3-adrenergic receptors immunohistochemically in human gastrointestinal smooth muscle and incidently found a population of human pancreatic islet cells and duodenal epithelial neuroendocrine cells that also expressed beta3-adrenergic receptors. AIM: To identify the nature of the islet and duodenal cells that stained positive for beta3-adrenergic receptors. METHODS: Paraffin sections of human pancreas and duodenum and Chinese hamster ovary cells transfected with the human beta3-adrenergic receptor were immuno-stained for beta3-adrenergic receptors using an affinity-purified rabbit polyclonal antibody (anti-P12) raised against a 15 amino acid sequence (P12) of the human receptor. Immunohistochemical staining for the receptor was carried out in the presence and absence of P12 peptide and both somatostatin 14 and 18 peptides. beta3-adrenergic receptor-stained sections were also double-immunostained with anti-insulin, -glucagon, -somatostatin and -pancreatic polypeptide antibodies. RESULTS: A subpopulation of human pancreatic islet cells and duodenal epithelial cells expressed positive cytoplasmic beta3-adrenergic receptor immunostaining. Using distribution and double-staining techniques, these cells were found to be somatostatin-positive D cells but not A or B cells. The positive staining of D cells with anti-P12 antibody was inhibited by prior incubation of the antibody with P12 peptide but not somatostatin-14 or -28 peptides. Pancreatic vascular smooth muscle and duodenal vascular and non-vascular smooth muscle also stained with anti-P12 antibody. Transfected Chinese hamster ovary cells showed positive membrane staining. CONCLUSION: We have identified a population of neuroendocrine cells in the human pancreas and duodenum that express beta3-adrenergic receptors. These cells appear to be somatostatin D cells.

Animals↗

PubMed2000

Quinine induced coagulopathy--a near fatal experience.

A 67 year old man presented to his local dentist for restorative treatment. He stated he was fit and well and denied taking any medications. When he was given an inferior alveolar nerve block, excessive bleeding was noted at the injection site and the dentist advised the patient see an oral and maxillofacial surgeon. An appointment was made for the patient but he did not attend. Three days later, he presented with evidence of massive deep haemorrhage to the point of airway compromise. He underwent hospital admission, early intubation, intensive care for nine days and hospitalization for six weeks. The cause of his bleeding was a severe thrombocytopoaenia, induced by chronic ingestion of quinine. He was self-medicating with this to relieve muscular cramps. Despite this experience, the patient continued to deny that quinine was the cause of his problem and that he had failed in his obligations to advise the dentist of his drug history. Dentists need to be alert to the risk that patients may not reveal their true medical history. There are, however, obligations on the dentist to ensure the accuracy of information the patient gives and to ensure that patients whom they believe are at risk follow their advice. Teamwork and skillful airway management prevented this patient's demise.

Aged↗

PubMed2000

Heterogeneous recognition of beta 2-glycoprotein I by antibodies from antiphospholipid syndrome patients.

Beta 2-glycoprotein I plays a pivotal role in the binding of antiphospholipid antibodies to phospholipid in patients with antiphospholipid syndrome. In this study the nature of the epitopes on beta 2-glycoprotein I (beta2-GPI) recognised by sera from antiphospholipid syndrome (APS) patients (n = 15) was investigated and compared to rabbit polyclonal and mouse monoclonal anti-beta2-GPI antibodies. beta2-GPI was only recognised when bound to a high affinity binding support. The antigenic epitope on beta2-GPI recognised by all APS patients was also dependent on disulphide bond integrity. Digestion of beta2-GPI with elastase rapidly destroyed the epitope(s) on beta2-GPI recognised by antibodies in 91% of APS patients. The main cleavage occurred at tryptophan316-lysine317 in the fifth domain. Digestion with staphylococcal V8 protease resulted in a 50% reduction in antibody binding in 81% of patients and the cleavage sites mainly involved the first domain of the molecule. There was considerable variability in the recognition of six different species of beta2-GPI by serum from APS patients. The epitopes on beta2-GPI bound by APS sera appear conformationally determined in all patients but are quite heterogeneous in the regions of beta2-GPI that are recognised.

Adsorption↗

PubMed2000

Squamous cell carcinoma of the temporal bone: diagnosis, treatment and prognosis.

Squamous cell carcinoma of the external ear canal is an uncommon condition that is associated with a poor outcome. The development of an accepted staging system has not been forthcoming and this has inhibited the formation of an evidence-based therapeutic protocol. We report the findings in 14 patients with squamous cell carcinoma of the external ear canal treated in our institutions. The most common presenting symptoms were otorrhoea and otalgia. Four patients had a history of chronic ear discharge and one had previous radiotherapy for nasopharyngeal carcinoma. Five patients had facial palsy which was a poor prognostic sign. Only one patient had clinical neck disease. Pre-operative imaging with CT or MRI scans was accurate in determining the extent of tumour involvement. The initial T-staging relied heavily on these findings. With combination treatment involving surgery, radiotherapy and chemotherapy, disease free survival achieved was 69% (9 of 13) over a mean follow-up period of 24.7 months. One patient absconded treatment. Patients with early stage tumours faired better than patients with advanced tumours (100% vs 33%). There was low incidence of involvement of the parotid gland (1 of 7 patients). Patients with facial nerve involvement had a significantly poorer outcome (p = 0.035).

Adult↗

PubMed2000

Laparoscopic colectomy for malignancy.

It is clear from published series that laparoscopic colectomy for cancer can be performed safely by experienced surgeons, but there is a considerable learning curve for the procedure. Although surgeons have shown that an equivalent resection can be performed, it is not clear yet that this translates into equivalent recurrence and survival rates. Most of the expected benefits of minimal access surgery are being provided by laparoscopic colectomy, although these benefits have not been as readily achievable as those seen with other procedures. Even the early results of laparoscopic colectomy for cancer are encouraging, although the fate of this procedure rests with the long-term analysis of a number of trials currently underway. Laparoscopic techniques are continuing to evolve and improve secondary not only to technological breakthroughs but also advances in basic science and clinical research. This article provides technical descriptions to illustrate key concepts in laparoscopic resection of the right colon and rectosigmoid for cancer and reviews the results of recent prospective randomized trials.

Colectomy↗

PubMed1999

Haemorrhage into non-functioning adrenal cysts--report of two cases and review of the literature.

Adrenal cysts are a rare condition and are usually non-functioning and asymptomatic. Most of the reported cases were incidental findings or discovered at autopsy. However, large cysts have a tendency to develop complications such as intracystic haemorrhage and rupture, which can present as an acute surgical emergency. We report two cases of adrenal cysts with intracystic haemorrhage. One patient presented with persistent non-specific upper abdominal pain, investigations with ultrasound (US) scan and computed tomographic (CT) scan revealed a left adrenal cyst and gallstones. Simultaneous cholecystectomy and adrenalectomy was performed with resultant relief of symptoms. The second patient presented with acute abdominal pain simulating acute surgical abdomen. Preoperative CT scan showed a large cystic lesion in the region of the tail of the pancreas with radiological evidence of haemorrhage but was unable to confirm its origin. The cyst was found to have arisen from the left adrenal gland at laparotomy; left adrenalectomy with complete excision of the cyst was done. Histology showed pseudocyst with haemorrhage in both cases. Pseudocyst is the commonest histological type encountered clinically. We believe the second case is related to pregnancy and childbirth as the patient presented during puerperium and the cyst, even though very large in size (25 x 15 x 15 cm), was not noted during antenatal screening with US scan.

Adrenal Gland Diseases↗

PubMed1998

Absence of Escherichia coli, Listeria monocytogenes, and Klebsiella pneumoniae antigens within inflammatory bowel disease tissues.

BACKGROUND: Escherichia coli, listeria, and streptococcal antigens have been found in Crohn's disease tissues. Antibodies to Klebsiella pneumoniae have been found in patients with inflammatory bowel disease and ankylosing spondylitis. The presence of these bacterial antigens in Crohn's granulomas would be of aetiological interest, while their presence in ulcers alone would be more likely to indicate secondary infection. AIM: To investigate inflammatory bowel disease tissues for the presence of these bacteria. METHODS: Formalin fixed, paraffin processed sections from 53 patients (19 ulcerative colitis, 23 Crohn's disease; 11 normal tissues from cancer resections) were studied by immunohistochemistry. Control tissue consisted of normal human small bowel injected submucosally with either E coli, Listeria monocytogenes, Proteus mirabilis, or Klebsiella pneumoniae serotypes K2, 3, 17, 21, 26, 36, and 50, and colonic biopsies from a child with E coli 0114 infection. Tissues were stained by Gram-Twort, and with specific antibodies for E coli (Dako B357), L monocytogenes (Difco 2302-50), and K pneumoniae (Biogenesis 5580-5208) using an immunoperoxidase technique. RESULTS: Positive staining for E coli was observed on the luminal surface epithelium and in ulcers in 35% of Crohn's disease patients, 26% of ulcerative colitis patients, and no normal controls. Superficial staining for L monocytogenes was observed in one case of ulcerative colitis only. Staining for K pneumoniae was observed in one case of ulcerative colitis and one of Crohn's disease. No granulomas, giant cells, or germinal centres stained positively for any of the three bacterial antigens. CONCLUSIONS: These data do not support a primary role for E coli, L monocytogenes, and K pneumoniae in inflammatory bowel disease. The presence of E coli antigens in ulcers suggests secondary infection in these lesions.

Antigens, Bacterial↗

PubMed1998

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.

Abdomen↗

PubMed1998

Surgical treatment of thyroid cancer: the Singapore General Hospital experience.

Patients with differentiated thyroid cancers generally have a good prognosis. This should be considered when deciding the extent of surgical resection. Radical surgery, however, may be appropriate in the control of locally advanced disease. An audit of 149 cases of thyroid cancer treated in the Department of General Surgery, Singapore General Hospital between October 1988 and June 1994 is presented. Particular attention is drawn to eight patients who underwent radical surgery. There were 111 (74.5%) women and 38 (25.5%) men. The median age was 45 years (range 12 to 83 years) and 80.5% of the cancers were papillary carcinomas, 14.8% follicular, 2.7% medullary and 2.0% anaplastic. Total or near-total thyroidectomy was the most common procedure for primary disease in about 75% of patients. Eight patients (5.4%) underwent radical surgery-four laryngectomy, one pharyngectomy and three median sternotomy-for tumour clearance. Morbidity included: wound complications in 2%; hypocalcaemia, transient in 16.8% and permanent in 3.4%; and hoarseness of voice in 8.1% with 4.7% having proved recurrent laryngeal nerve palsy. All three patients with anaplastic thyroid cancer died within 3 months. Of the eight who underwent radical surgery, three (37.5%) are alive and disease-free at median follow-up of 20 months. In a correctly selected group of patients with locally invasive differentiated thyroid cancer, aggressive surgery is appropriate, with acceptable morbidity and mortality.

Adolescent↗

PubMed1998

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.

Adolescent↗

PubMed1997

In situ immune responses in Crohn's disease: a comparison with acute and persistent measles virus infection.

The implied aetiological association of measles virus with Crohn's disease would be supported by detection of an immune response to infected cells in affected tissues. This study sought to detect and characterise in situ immune responses to measles virus in both acutely and persistently infected tissues, and in particular, Crohn's granulomata. Tissue sections from patients with Crohn's disease (n = 17), tuberculosis (n = 9), acute intestinal ischaemia (n = 5), acute measles pneumonitis (n = 2), acute measles appendicitis (n = 1), subacute sclerosing panencephalitis (SSPE; n = 1), and measles inclusion body encephalitis (MIBE; n = 1), were examined. Single and double immunohistochemical labelling was performed to identify both cytotoxic lymphocytes (CD8, TIA, perforin, Leu 7, CD45RO, CD45RA) and macrophages (KP1). The relationship of these cells to measles infected cells was examined by double immunolabelling with antimeasles virus nucleoprotein antibody. In both acute measles appendicitis and SSPE, CD8+/TIA cytotoxic lymphocytes (CTL) targeted infected cells. In the cases of Crohn's disease (13/17), MIBE, fatal pneumonitis, and one tuberculous granuloma, that were positive for measles virus, infected cells appeared to be targeted by macrophages rather than CTL. CTL in both tuberculous and Crohn's granulomata were similar in their peripheral distribution, number, and phenotype. The data suggest that measles-specific CTL responses may be attenuated in Crohn's disease compared with acute measles appendicitis and SSPE, and secondly, that an abnormal macrophage response to persistent measles virus infection of the intestine may result in granulomatous inflammation.

Acute Disease↗

PubMed1996

Direct in situ reverse transcriptase polymerase chain reaction for detection of measles virus.

New methods are described for combined intracellular reverse transcription (RT) and polymerase chain reaction (PCR) using single primer pairs, with direct incorporation of digoxigenin-11-dUTP into amplificants (direct in situ RT/PCR). Routinely used fixatives and minimal pre-treatments were employed. Target sequences of measles virus nucleocapsid (N) and phosphoprotein genes were detected within measles virus infected Vero cells, both in suspension and in formalin-fixed sections, that had been treated by in situ reverse transcription and 30 cycles of direct in situ PCR. Uninfected cells, omission of Taq polymerase, and irrelevant primers were used as controls. Distribution of measles virus within infected cells was determined by in situ hybridisation and immunocytochemistry for measles virus N gene and protein, respectively. Confirmation of amplification within sections was by gel electrophoresis, Southern blotting and sequencing of extracted amplicons. In the majority of cases, measles-infected cells exhibited intense cytoplasmic signal after direct in situ PCR; this was not seen in uninfected cells or infected cells reacted either with irrelevant primers or without Taq polymerase. Unfixed cells in suspension required nested reaction. Measles-specific in situ hybridisation and immunocytochemistry gave an identical signal distribution in sections. Nuclear artifact occurred in some sections and was unpredictable, although it was greatest either in areas of cellular damage, following DNase predigestion, or with vigorous protease pre-treatment. In situ RT-PCR is feasible for measles virus in acutely infected cells both in sections and in suspension. Further work is required to improve the procedure and to eliminate artefactual nuclear signal.

Animals↗

PubMed1996

Gastric mucosal contraction and vascular injury induced by indomethacin precede neutrophil infiltration in the rat.

BACKGROUND: In contrast with earlier reports that neutrophils play a primary part in non-steroidal anti-inflammatory drug (NSAID) injury to the stomach, recent evidence suggests only a secondary role for these cells. AIM: To examine whether early microscopic changes induced by indomethacin in the gastric corpus of fasted rats and the antrum of fasted-refed rats involve neutrophil infiltration. METHODS: Oral indomethacin 30 mg/kg or vehicle was given to six groups of fasted rats that were killed five, 15, and 30 minutes after dosing. Subcutaneous indomethacin 30 mg/kg was also given to six groups of fasted-refed rats that were killed one, two, and four hours later. Haematoxylin and eosin and reticulin stained sections were examined to identify mucosal architectural changes. The gastric mucosa was also examined immunohistochemically for actin, fibrin, and neutrophils. RESULTS: In both the corpus and antrum, indomethacin caused an early phase of mucosal injury that occurred prior to mucosal neutrophil infiltration. Within the superficial corpus mucosa, this phase preceded coagulative necrosis and included surface epithelial expulsion, mucosal contraction with capillary aggregation and distortion, intravascular vascular fibrin deposition, and capillary congestion. The antrum showed similar early changes except that full thickness mucosal coagulative necrosis was a predominant early finding. CONCLUSIONS: In two experimental models of NSAID gastric ulceration the mucosa undergoes early contraction, vascular fibrin deposition, and necrosis prior to neutrophil infiltration. These findings support a primary, neutrophil independent, ischaemic pathogenesis for NSAID gastric ulceration.

Animals↗

PubMed1996

Case report of acute splenic and superior mesenteric vein thrombosis and its successful medical management.

We report a case of a 27-year-old pregnant patient who presented with severe colicky abdominal pain, diarrhoea and fever. She was initially treated for gastroenteritis. She later requested a termination of the pregnancy. Abdominal X-rays showed small bowel dilatation. A dynamic computed tomographic scan was performed and showed a splenic and superior mesenteric vein thrombosis. This was confirmed by colour duplex scanning and angiography. Anticoagulation with heparin was associated with dramatic relief of the symptoms and complete recanalisation of both veins. Surgical intervention was avoided.

Abortion, Therapeutic↗

PubMed1995

The intracellular polymerase chain reaction for small CMV genomic sequences within heavily infected cellular sections.

The indirect intracellular polymerase chain reaction (in situ PCR) combines the potential sensitivity of the polymerase chain reaction (PCR) with the high specificity and morphological preservation of in situ hybridization (ISH). This study describes a method for the amplification of small, specific cytomegalovirus (CMV) genomic sequences [100 base pairs (bp)] within large formalin-fixed, paraffin-embedded tissue sections. A heat-resistant glue surrounds the section, creating a well which contains a relatively large volume of isotonic reaction solution without a covering mineral oil layer; this optimizes morphological preservation, permits the evaluation of large sections, and allows both denaturation steps and up to 40 cycles of in situ PCR to be performed, whilst progressively concentrating the reaction solution by evaporation during thermal cycling. ISH was performed using a non-isotopic DNA probe with specificity for CMV, with or without prior in situ PCR amplification, both for samples on slides (fibroblasts and lung) and in suspension (fibroblasts). Samples on slides were evaluated by both blinded studies and image analysis, comparing the intensity of signal (P < 0.003) and the numbers of positive cells detected (P < 0.007), with or without intracellular amplification. Cells in suspension were analysed by blinded studies on cytospins and by gel electrophoresis of cell lysates. Successful intracellular amplification was achieved in this high copy model.

Base Sequence↗

PubMed1995

In situ hybridization detection of short viral amplicon sequences within cultured cells and body fluids after the in situ polymerase chain reaction.

Using single primer pairs, intracellular gene sequences of cytomegalovirus (CMV-Towne's strain) and alpha-tubulin were amplified (in situ PCR) from cells in human body fluids and in suspensions. Visualization of CMV amplificants was carried out by in situ hybridization (ISH), using both a biotinylated double-stranded DNA probe and a radiolabelled oligonucleotide probe. Visualization of alpha-tubulin amplificants was achieved using both radiolabelled single-stranded cRNA and oligonucleotide probes. Liberated amplificants were also identified by bands of expected size by gel electrophoresis. The specificity of the PCR products was confirmed by Southern blot analysis. Intracellular amplification was identified both in unfixed cells and, optimally, after brief alcohol fixation, whilst maintaining relative isotonicity in all working solutions. For CMV, enhanced signal was observed in cells (cultured fibroblasts or urine sediment) undergoing in situ PCR using either biotinylated or radiolabelled probes compared with controls undergoing ISH alone. For alpha-tubulin, radiolabelled riboprobes and oligoprobes only produced signals within cells (human peripheral lymphocytes, ascitic fluid and bladder washings from routine cytological specimens) after in situ PCR, but not after ISH alone. Morphological evaluation was superior with biotinylated probes, and minimal back-diffusion effect was found compared with radiolabelled probes. Up to 80% of cells survived thermal cycling. In situ PCR detected short sequence (100 bp) foreign DNA and low copy number genomic DNA, and was superior to ISH alone. In contrast to radiolabelled probes, very small CMV amplificants could be detected without a significant 'back-diffusion' effect when using the large biotinylated probe in this model system.

Animals↗