Endoscopic monopolar coagulation of internal haemorrhoids: a surgeon's experience of the first 100 cases.

AIM: The purpose of this study was to evaluate one surgeon's initial experience with a novel technique of retroflexed endoscopic coagulation of internal haemorrhoids. METHOD: Patients who presented with symptoms and signs indicating Grade II-III haemorrhoids were counselled before the procedure. Those who were assessed to require an examination of their colon, based on their age and symptoms, underwent a full colonoscopy before treatment of the haemorrhoids. After the procedure, patients were routinely prescribed nonsteroidal anti-inflammatory drugs, antibiotics and laxatives. RESULTS: The first 100 patients of median age 52.0 (20.8-78.5) years included 65 (65%) women. Five (5%) patients suffered from postprocedural complications, of which three (3%) were postprocedural bleeding and two (2%) were postprocedural pain, all treated conservatively. The recurrence rate was 6% at a median follow-up time of 36 (6-76) months. The median duration of follow-up was 36.5 (8.5-57.0) months. CONCLUSION: This novel technique appears to be safe and effective for the treatment of Grade II-III internal haemorrhoids, and can be incorporated seamlessly into the end of a colonoscopy for the evaluation of haematochezia. Comparative trials should be performed.

Exploiting internal ribosome entry sites in gene therapy vector design.

Efficient and regulated co-expression of multiple genes is an important consideration in the design of gene therapy vectors. While the augmentation of a single therapeutic gene is often sufficient for gene therapy of simple mendelian disorders, strategies for the treatment of complex disorders and infectious diseases necessitate the introduction of multiple genes into the cell. Complex disorders such as cancer often involve mutations in multiple genes and a combination strategy targeting different defective genes simultaneously are often more effective than any single strategy. Likewise, approaches for treating infectious diseases such as HIV-1 (human immunodeficiency virus) often involve the blocking of multiple steps of the viral replication pathway simultaneously to prevent the emergence of resistant strains of the virus. Even for the treatment of single gene defects, the additional incorporation of a selectable marker gene is often necessary to achieve sustained expression of the therapeutic gene in the cells. Among the several different strategies to co-express multiple genes, the incorporation of an IRES (internal ribosome entry site) into gene therapy vector design represents one of the more promising strategies. IRES functions as a ribosome-landing pad for the efficient internal initiation of translation ensuring coordinate expression of several genes and are located at the 5'UTR (5' untranslated regions) of these genes. Currently, the most popular IRES utilized for gene therapy is the IRES from the EMCV (encephalomyocarditis virus). However, the major caveat with present vector systems utilizing this IRES is that the expression of the downstream gene is significantly less efficient than the upstream gene. This review will examine the growing list of naturally occurring and synthetic IRESes and how they can be exploited for human gene therapy.

Routine use of setons for the treatment of anal fistulae.

AIM: Anal fistula is usually treated by either fistulotomy or fistulectomy. We described the routine use of setons to treat anal fistula without any surgery. METHOD: Forty-seven consecutive patients with diagnosed anal fistulae were treated using setons alone. RESULTS: The median age of the patients was 41 (range: 18-70). Of the 47 patients, 15 had surgery previously for fistula and perianal abscess. At least two setons were inserted through each fistula. One was tied tightly to function as a cutting seton and this was sequentially tightened by the patient and another was tied loosely for drainage. Of the 47 patients, 33 (70%) had the placement of setons in the clinic without any anaesthesia. The remaining 14 patients had the setons inserted in the operating room, with one patient having a complex anal fistula and 13 patients having perianal abscess requiring drainage at the same time. There were no post procedure complications in the series. Forty-one patients had completed follow up at clinic within a median duration of 15 weeks (range: two to 67 weeks). The fistula was completely healed by this method in 37 patients (78%). The median healing time was nine weeks (range: four to 62 weeks). One patient developed recurrent fistula and was healed after another seton placement. No patient developed any faecal incontinence and all patients were satisfied with this treatment. CONCLUSION: The routine seton method is safe, cheap and effective in the treatment of anal fistula regardless of type. It does not leave an open wound and most patients are satisfied with the treatment.

Improved co-expression of multiple genes in vectors containing internal ribosome entry sites (IRESes) from human genes.

Incorporation of an internal ribosome entry site (IRES) into the gene therapy vector represents a promising strategy to efficiently co-express several gene products from the same promoter. However, vector systems that utilize the encephalomyocarditis virus IRES express the downstream gene much less efficiently than the upstream gene. In this study, we compared four IRESes isolated from human genes against the EMCV IRES, using beta-galactosidase and chloramphenicol acetyl transferase genes as reporters, to evaluate their potential for providing better expression of the downstream gene. We found that an IRES from the eukaryotic initiation factor 4G gene mediates greater than 100-fold higher expression of the downstream gene compared with the EMCV IRES in four different cell lines tested. Other mammalian IRESes displayed more variable results and smaller enhancement of downstream gene expression in three different cell lines tested. Furthermore, while the efficiency of the IRES from the vascular endothelium growth factor gene was not significantly higher than the EMCV IRES under normoxic conditions, expression was significantly increased under hypoglycemic conditions, suggesting that the VEGF IRES could be exploited in cancer gene therapy to preferentially target expression of therapeutic genes at the relatively hypoglycemic cores of tumors.

Expression of nitric oxide synthase, cyclooxygenase, and p53 in different stages of human gastric cancer.

The present study evaluated the significance of nitric oxide synthase (NOS), cyclooxygenase (COX) expression and p53 status in 55 patients with gastric adenocarcinoma and relationship of these molecular markers to tumor characteristics and metastatic potential. Immunohistochemical technique was used to identify the cellular location and distribution of the enzymes in the specific cells of gastric tumors. In gastric cancer tissue, the expression of inducible enzymes, iNOS and COX-2, increased significantly with increasing tumor stage (P=0.015, P=0.001, respectively), size (P=0.025, P=0.001, respectively) and the presence of metastases (P=0.002, P=0.015, respectively). The expression of constitutive enzymes, ecNOS and COX-1, followed the opposite pattern. COX-1 was significantly reduced in advanced gastric tumors (P=0.007) and tumors larger than 5 cm (P=0.007). Reduced expression of ecNOS was also observed in advanced gastric tumors; however, this did not reach statistical significance. 53% of gastric tumors showed accumulation of p53. This was significantly higher in advanced tumors (P=0.004), larger than 5 cm (P=0.015) with metastases (P<0.001). Gastric tumors positive for accumulation of p53 had significantly stronger expression of iNOS (P=0.018) and COX-2 (P=0.01) enzymes than tumors negative for this nucleophosphoprotein. We conclude, that tumor-associated nitric oxide production, as well as COX-2 overexpression, may promote gastric cancer progression by providing a selective growth advantage to tumor cells with non-functioning p53.

Right-sided colonic diverticular disease as a source of lower gastrointestinal bleeding.

Right-sided colonic diverticular disease is a distinct disease entity uncommon in the West. Occasionally, the condition may be complicated by hemorrhage and present as lower gastrointestinal bleeding. We report a series of 25 cases of bleeding right colon diverticulosis and discuss its presentation and management. Patients were selected from the colonoscopic reports of all 190 patients presented with suspected acute lower gastrointestinal bleeding in National University Hospital, Singapore, from 1988 to 1994. Fifty-seven patients (30%) had bleeding diverticulosis in which 25 patients (44%) suffered from right-sided disease. Sixty-four per cent of patients had a history of hypertension. Patients presented with either fresh blood in stools or melena. Fifteen patients (60%) required blood transfusion (median, 2 units). Colonoscopy showed blood clots in the right colon in 15 cases (60%) and active bleeding from the right colon diverticula in 3 patients (12%). The bleeding stopped spontaneously in 16 patients (64%). The other 9 patients required surgery because of continuous or recurrent bleeding. All had a right hemicolectomy performed. The hospital stay was 13 days in this group, compared with 5 days for those undergoing conservative treatment (P = 0.0004). There were no deaths. No patients had further bleeding episodes during a median 7-month follow-up.

Needlescopic or minisite cholecystectomy.

Needlescopic or minisite cholecystectomy is laparoscopic cholecystectomy done through tiny ports from 1.4 mm to 3 mm in size. This refinement of conventional laparoscopic cholecystectomy reduces further the invasiveness of the operation and gives an improved cosmetic effect. This series describes the result of 36 needlescopic cholecystectomies done between February 1996 and April 1997. Patients with acute cholecystitis were excluded. There were two conversions to conventional laparoscopic surgery and no conversions to open surgery. Thirty-four patients were successfully treated by this technique. Analgesic consumption and cosmetic result was superior compared to a previous published series of conventionally done cases in the same department.

Management of Mirizzi's syndrome in the laparoscopic era.

BACKGROUND: Mirizzi's syndrome is an uncommon cause of common hepatic duct obstruction resulting from gallstone impaction in the cystic duct or gallbladder neck. The role of laparoscopic surgery in the treatment of this condition is still not well defined. This article reports six cases of Mirizzi's syndrome and comments on the management of this condition using the laparoscopic approach. METHODS: A review of 878 consecutive cholecystectomies from July 1991 to July 1996 identified six cases of Mirizzi's syndrome (0.7%) that were approached laparoscopically. RESULTS: This study involved three men and three women with mean age of 64 (range, 57-70) years. All cases were approached by laparoscopy. One case was converted because of unclear anatomy in the Calot's triangle due to dense adhesions; open cholecystectomy, exploration of the common bile duct and T-tube insertion was performed. The other five cases were successfully managed laparoscopically. Subtotal cholecystectomy was performed in two cases, and in three patients with cholecystocholedochal fistula, the defect was closed over a T tube. There was no postoperative morbidity or mortality. A follow-up period of 8 to 17 (mean, 12) months revealed no complications. CONCLUSIONS: Laparoscopic management of Mirizzi's syndrome is feasible and safe but can be technically demanding. A policy of trial dissection by an experienced laparoscopic surgeon is recommended, and if anatomy remains unclear, it is prudent to convert.

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.

A study of the effects of bowel preparation on CEA levels in patients undergoing surveillance colonoscopy.

Mechanical bowel preparation has been postulated to be another cause of "false rise' of serum carcinoembryonic antigen (CEA) levels. Furthermore, it was shown that high-risk patients for colorectal cancer had a greater rise in serum CEA after bowel preparation. To verify these findings, a prospective study of 24 consecutive patients in our surgical endoscopic unit on the effect of mechanical bowel preparation of serum CEA level as carried out from January to March 1994. Blood samples were taken before and after bowel preparation for patients undergoing surveillance colonoscopy for various reasons. Our study did not show any relationship between serum CEA levels and bowel preparation. No rise of serum CEA was found even in high-risk patients after bowel preparation.

Intermittent subacute intestinal obstruction due to a giant lipoma of the colon: a case report.

A case with intermittent subacute intestinal obstruction due to a giant lipoma of the colon is reported. A 57-year-old woman presented with intermittent pain in the central abdomen and clinical findings of subacute intestinal obstruction. She had had similar symptoms for the last five years. She was diagnosed to have a large polypoid lesion in the ascending colon on barium enema in 1990. However, no surgical treatment was offered to her at that time. At laparotomy, a 16 cm x 11 cm x 11 cm polypoid mass on a 3 cm long stalk in the ascending colon causing colo-colonic intussusception was seen. Subtotal colectomy was performed. Histology showed submucosal colonic lipoma.

Novel alternative splicing predicts a secreted extracellular isoform of the human receptor-like protein tyrosine phosphatase LAR.

RT-PCR was used to examine the expression of LAR (encoding the leukocyte-common antigen-related protein tyrosine phosphatase) in normal human colon mucosa, and colon polyps and tumors. Although the LAR protein was not detected in the colon in a previous immunohistochemical study, amplification of a region of LAR between the most membrane proximal (eighth) fibronectin type-III (FN-III) repeat and the transmembrane domain demonstrated LAR expression in all samples, but showed no difference in expression within matched samples from each patient examined. An additional minor fragment amplified in all reactions was consistently observed in colon and various cell line samples using this and two other LAR-specific sets of primers. Cloning and sequencing of the fragment identified it as deriving from a novel alternatively spliced form of LAR containing a retained intron of 85 bp. This intron encodes an additional 13 amino acids followed by an in-frame stop codon, thus its retention is predicted to give rise to a secreted LAR extracellular region isoform(s). LAR transcripts containing the intron were detected by RNase protection assay of colon samples and were present in most human tissues examined by Northern analysis. A protein in colon tumor extract was recognized by antiserum raised to the intron-encoded sequence. Soluble isoforms of the LAR extracellular immunoglobulin (Ig)-like/FN-III repeat-containing region could have a biological function distinct from those isoforms localized at the cell surface and/or coupled to intracellular phosphatase activity.

Randomized trial of periportal peritoneal bupivacaine for pain relief after laparoscopic cholecystectomy.

The aim of this study was to determine whether injection of a long-acting local anaesthetic, in relation to the port sites at the level of the parietal peritoneum, would reduce postoperative pain following laparoscopic cholecystectomy. Patients were entered into a randomized, prospective, double-blind study comparing the effects of a standard technique, in which bupivacaine (total of 20 ml, 0.5 per cent) was injected into the subcutaneous periportal tissue around the four port sites, and a technique in which bupivacaine (total of 20 ml, 0.25 per cent) was injected into the subcutaneous periportal tissue as above with the addition of periportal parietal peritoneal injection of bupivacaine (total of 20 ml, 0.25 per cent). Two scores for pain, with the patient at rest, and on movement, were assessed 6 and 18 h after surgery using a visual analogue pain scale. Median pain score was significantly higher in patients who received standard technique (n = 40) than in those given peritoneal injection (n = 40) at both 6 (rest = 3.0 versus 1.0, movement = 5.0 versus 2.9) and 18 h (rest = 1.9 versus 0, movement = 3.2 versus 1.2). Both opiate and oral analgesic requirements were reduced in patients administered peritoneal injection, although this was not statistically significant. The addition of periportal injection of bupivacaine at the level of the parietal peritoneum, performed under direct vision, reduces pain after laparoscopic cholecystectomy.

Laparoscopic-assisted large bowel resection.

Laparoscopic colon resection is a viable alternative to open colectomy. For non-malignant lesions, laparoscopic resection of the affected large bowel is attractive. For malignant lesions, where resection for cure is highly dependent on lymph node clearance, laparoscopic resection has met with criticisms regarding the adequacy of nodal clearance that can be achieved laparoscopically. Several published studies have shown that the operation though technically demanding, does not compromise the extent of resection. We report a series of 43 cases of laparoscopic colon resection done sequentially and successfully from January 1992 to June 1995. The operative time averaged 180 minutes (range 120 to 300 minutes). Five patients developed postoperative complications, which were mainly pulmonary and wound infections. There were no anastomotic leaks or perioperative deaths. The mean hospital stay was 5.3 days (range 4 to 9 days). By the third postoperative day, all patients were feeding and ambulatory. Long-term complications included one small bowel obstruction and one port site recurrence. In our selected group of patients, laparoscopic colon resection has not shown any adverse outcome. Prospective randomised studies are underway in various centres and their preliminary results are favourable.

Towards a more minimally invasive laparoscopic cholecystectomy--a viewpoint.

The advent of laparoscopy and its associated instrumentation in the treatment of gallstone disease heralded a new revolution in surgery. The obvious advantages of cosmetically superior scars and low morbidity have made the minimally invasive approach the preferred choice in the removal of the gallbladder with its stones. Several modifications to the technique have now made it possible to perform cholecystectomy via fewer and smaller port sites. This has translated into even lower postoperative pain and faster recovery times.

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.

The human leucocyte antigen complex: its role in colorectal cancer.

The human leucocyte antigen (HLA) is frequently altered in human tumours compared to the tissue from which they originate. The ability of the tumour to invade requires a change in the phenotype of the cell allowing it to advance and expand without restraint from adjacent tissue and the host immune system. One important regulator of tumour growth is cellular immunity. Antigen recognition by "T" cells occurs in the context of the HLA products. Changes in the HLA expression of a malignant tissue may directly influence immunosurveillance mechanisms, as these molecules play a central role in presenting potentially immunogenic peptides to "T" cells. To assess whether alteration in HLA expression is a critical step in the multistep origin of tumours, it is important to examine the HLA expression in premalignant precursor lesions of tumours and in tumours themselves. Our studies have recently reported a downregulation of HLA class I expression in colorectal cancers and adenomatous polyps when compared to normal appearing mucosa adjacent to the cancer. Our study on the class I antigen expression showed the presence of the antigen on all samples of control colonic epithelium. In sporadic adenomatous polyps of the colorectum, 21% (n = 7) of adenomas expressed levels of HLA that were comparable to controls, 51% (n = 17) expressed low levels, and in 28% (n = 9) the antigen was undetectable. Similarly, in colorectal adenocarcinomas the antigen was reduced even further with levels comparable to controls in 5% (n = 2) of tumours, reduced in 30% (n = 6) and undetectable in 65% (n = 13). This abnormality may result in the loss of immunosurveillance which could be one mechanism by which cancer cells can evade "T" cell control, thus resulting in invasion and metastasis.