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Biomedical subjects

S S Ngoi

Publications and source records attributed to S S Ngoi.

At least 19 recordsLinked to original sources
PubMed1992

Loss of colonic HLA antigens in familial adenomatous polyposis.

The loss of HLA antigens by neoplastic cells is considered important for tumor growth and metastasis, since it may allow tumors to escape immune surveillance. We studied the expression of HLA class I and II antigens in the colons of 10 patients with familial adenomatous polyposis (FAP), a condition which leads inevitably to colorectal cancer. Expression of HLA class antigens was studied by immunohistochemistry in (a) adenomas from patients with FAP, (b) histologically normal mucosa distant from the adenomas, and (c) histologically normal colonic mucosa from normal subjects. The expression of HLA class I and II antigens was decreased in histologically normal mucosa from FAP patients compared to normal controls. Adenomas showed a similar but quantitatively more pronounced reduction (or loss) of HLA antigen expression. The reduction of HLA expression in adenomas was comparable to that observed in sporadic colon carcinomas. This generalized suppression of HLA gene expression in the colon of FAP patients, which precedes the onset of overt histological manifestations of neoplasia, may be an important early event in colon carcinogenesis.

Adenomatous Polyposis Coli↗
PubMed1992

Surgical management of right colon diverticulitis.

The infrequent occurrence of right colon diverticulitis in the developed West has led to a controversy in the management of this disease. In Singapore, we continued to avoid colectomy whenever possible because this disease is usually nonprogressive. We reviewed 68 patients treated by conservative surgery to evaluate the effectiveness of this treatment policy. Almost 70 percent of our patients were below 40 years of age, and the clinical presentation was indistinguishable from acute appendicitis. Diverticulectomy was done only for inflamed and perforated diverticula (25 cases), while the nonperforated diverticulum was left alone (40 cases). The inflammation invariably responded to antibiotic therapy. Only three patients had colonic resection since a malignant neoplasm could not be excluded. There were no adverse sequelae over a mean follow-up period of three and one-half years, except for one patient who had recurrent attacks of right colon diverticulitis necessitating colectomy. With this policy of management we encountered no mortality, and morbidity was acceptable.

Adult↗
PubMed1992

Technical modification to laparoscopic appendectomy.

An alternative technique for laparoscopic appendectomy is described. The isolated appendix is exteriorized through the trocar wound, ligated, and resected. The cecum is then returned to the abdomen.

Appendectomy↗
PubMed1992

Laparoscopic cholecystectomy in a patient with empyema of the gallbladder and situs inversus.

The successful performance of laparoscopic cholecystectomy in a patient with situs inversus viscerum and empyema of the gallbladder is reported. The 62-year-old man presented with pain in the left upper quadrant associated with fever, chills, nausea and vomiting. The abdomen was tender with guarding and a palpable globular mass in the same region. CT scan demonstrated a distended gallbladder with thick shaggy walls which contained a 2 cm gallstone in the neck and also revealed dextrocardia and situs inversus. The patient's postoperative recovery was uneventful.

Cholecystectomy, Laparoscopic↗
PubMed1992

The surgical treatment of multiple small bowel strictures in Crohn's disease by combined resection and stricturoplasty.

Crohn's disease is extremely rare among Asians. Resection of strictures causing obstruction has traditionally been the accepted choice in surgical therapy. This may lead to problems such as iatrogenic short bowel syndrome and its sequelae. Stricturoplasty is an acceptable and safe alternative. We report a case where combined stricturoplasty and resection was performed safely and advocate its use.

Adult↗
PubMed1992

The technique of laparoscopic Billroth II gastrectomy.

This report describes the technique of totally intra-abdominal Billroth II gastrectomy. Because the procedure is minimally invasive, patient recovery is remarkable compared with the conventional open technique. The development of this procedure completes the minimally invasive revolution in the management of peptic ulcer disease, which began with the introduction of laparoscopic vagotomy.

Aged↗
PubMed1992

Clostridial septicemia in an urban hospital.

The records of 56 patients at an urban hospital who had positive blood cultures for clostridia were reviewed. Each patient was classified as immunologically normal or immunosuppressed. Data were collected on clinical history, type of clostridial bacteremia, physical and laboratory determinants of infection, therapeutic intervention, clinical course and outcome. Of the 56 patients, 22 were determined to be immunosuppressed. Among all 56 patients, 28 had a malignancy, usually gastrointestinal or hematologic in origin. Fever, leukocytosis and abdominal pain were common in both groups. Clostridial bacteremia almost always heralded clostridial septicemia. A gastrointestinal source of infection, particularly carcinoma of the colon or rectum or enterocolitis, was evident or presumed in 43 of the 56 patients. Clostridium perfringens was the most frequently isolated microorganism, but C. septicum was associated with more complications and a higher mortality rate. Septic complications and mortality were higher among the patients with immunosuppression.

Adolescent↗
PubMed1991

Ploidy in invasive colorectal cancer. Implications for metastatic disease.

A retrospective study was performed to determine the ploidy of superficial (above muscularis propria) and deep (below muscularis propria) biopsy specimens from the primary colorectal cancer of 88 patients with Dukes Stage C2 and D colorectal tumors. The ploidy of lymph node and liver metastases was compared with that of the superficial and deep specimen from the corresponding primary tumor. Among the tumors studied, 78% exhibited nondiploid stemlines. In 19% of the tumors, the ploidy of the superficial biopsy differed from that of the deep biopsy. Among these discordant tumors, all of the deep biopsy specimens corresponded in ploidy to the liver metastases, whereas most of the superficial specimens were similar in ploidy to the lymph node metastases. Our observations suggest that measurement of a single site may not be sufficient to detect nondiploid stemlines within a tumor. They also suggest that measurement of deeper parts of invasive tumors may be more reflective of the phenotype of distant metastases than measurement of superficial specimens.

Colorectal Neoplasms↗
PubMed1991

Primary resection and anastomosis in obstructed descending colon due to cancer.

Intraoperative colonic irrigation followed by one-stage resection is gaining popularity as the optimal surgical treatment for left-sided colonic obstruction. However, its efficacy and potential hazards have not been adequately tested in obstruction due to colonic cancer. We analyzed the early results of 23 consecutive patients with obstructive left-sided colonic carcinoma treated by primary resection and anastomosis following intraoperative antegrade colonic lavage. Two patients (8.6%) died, one from complication of anastomotic leakage. The significant postoperative complications were chest infection in three (13%) and wound infection in seven (30.4%). The average hospital stay was 16.5 days. The results of this study suggest that intraoperative bowel irrigation permits one-stage resection and anastomosis to be conducted with reasonable safety provided care is taken in operative techniques.

Adenocarcinoma↗
PubMed1991

Trends of diverticular disease of the large bowel in a newly developed country.

Five hundred twenty four consecutive barium enemas done over an 18-month period were reviewed in Singapore to ascertain the prevalence and distribution of diverticular disease in the large bowel. In this study, the prevalence rate was 20 percent, which is comparable to European and American studies but higher than similar studies in Asian countries. However, the distribution of the disease showed a predominance of right-sided disease (70 percent). This is a pattern that is markedly different from that seen in Europe and North America, where the disease involves largely the left side of the large bowel. The high prevalence rate in this series is at variance with the widely held belief that diverticulosis occurs less frequently in oriental communities.

Adolescent↗
PubMed1991

Endoscopic Nd:YAG laser in the palliative treatment of advanced low rectal carcinoma in Singapore.

We used the Nd:YAG laser to palliate symptoms of bleeding and obstruction in 27 cases of rectal carcinoma. Twenty of these patients had advanced inoperable rectal carcinoma, three were at high surgical risk, and four refused surgery. Obstructive symptoms were the main complaint in 10 cases, while 17 patients presented with bleeding. Good palliation of obstructive symptoms was achieved in all obstructive cases with one laser treatment session. However, bleeding tumors required an average of two sessions for complete hemostasis. There were no major complications; minor complications of bleeding after treatment occurred in two patients. Good symptomatic relief was achieved in all cases. The mean survival for all patients was five months. Nd:YAG laser therapy is a safe and efficacious means for palliation of obstructive symptoms and bleeding in advanced rectal carcinoma.

Aged↗
PubMed1991

Use of the optical urethrotome knife in the treatment of a benign low rectal anastomotic stricture.

Several methods of treatment for benign anastomotic strictures following anterior resection have been described. Surgical intervention in terms of re-exploration and excision of the stricture or the formation of a permanent colostomy will be accompanied by substantial morbidity. The dilatation of these strictures without direct vision may not be safe. We describe a simple method of treating benign rectal anastomotic stricture using an optical urethrotome knife under direct vision. This technique affords an accurate incision of the stricture to increase the size of the lumen, thereby relieving obstruction.

Anastomosis, Surgical↗
PubMed1991

Safe and rapid palliation of dysphagia for carcinoma of the esophagus.

Patients with carcinoma of the esophagus continue to present late when their tumors are inoperable. This makes palliation of their dysphagia the main therapeutic aim. The Nd-YAG laser has been used in our department to treat dysphagia resulting from cancer of the esophagus since 1986. Our rapid, one-stage cannulation technique using the Nd-YAG laser in both contact and noncontact modes was applied to 35 cases of carcinoma of the esophagus with the aim of achieving rapid and safe palliation of dysphagia. During the treatment we aimed not to coagulate the tumor and await sloughing, but to vaporize the tumor and ablate as much as possible in a single session. In this way there was less need for repeat sessions to create an adequate lumen. In a small number of patients (9) who had tight strictures with no visible lumen, a pre-laser dilation was required to allow visualization of the lumen and tumor vaporization. For nondilated patients (26) we achieved a 15-mm lumen in an average of 1.6 sessions, and in the dilated patients (9) this was achieved in one session in all patients. Functional improvement occurred in 28 patients (80%). There were four minor complications and no mortality associated with the procedure.

Aged↗
PubMed1990

Reduced expression of HLA class I and II antigens in colon cancer.

The expression of HLA class I and II antigens was studied by immunohistochemistry in (a) specimens of colon cancer from 25 patients, (b) normal colonic mucosa obtained 5-10 cm away from each tumor, and (c) colonic mucosa from 13 normal individuals. Thirteen of the tumor specimens had normal epithelium adjacent to the cancer, which thus served as an internal control. The expression of HLA class I antigens in colon cancer was dramatically reduced compared to control (P less than 0.0001): undetectable in 28%, diminished in 68%, normal in 4%. The expression of class II antigens was also reduced in cancer (P less than 0.0001 for all when compared to normal), being undetectable in most (HLA-DP 64%, HLA-DQ 72%, HLA-DR 68%). In 44% of the cancers all three HLA class II antigens were undetectable; in 92% at least one class II antigen was undetectable; and in 20% both class I and class II antigens were undetectable. No cancer specimen had a completely normal HLA phenotype. The expression of other surface antigens was preserved in cancer tissues and, therefore, loss of HLA antigens was not due to a nonspecific decline in surface molecules. When glands of normal mucosa immediately adjacent to cancer were compared to those of normal controls, significantly reduced expression of only HLA class I antigens (P = 0.0149) and HLA-DP (P = 0.034) was found. The expression of the HLA antigens in colonic mucosa remote from the cancer was no different from that of normal controls. Our data show extensive and significant reduction in the expression of HLA antigens in colon cancer; its potential relationship to immunosurveillance in cancer is discussed.

Colon↗
PubMed1990

Abnormal DNA ploidy and proliferative patterns in superficial colonic epithelium adjacent to colorectal cancer.

Superficial colonic cells were taken from normal-appearing mucosa at 2, 5, and 10 cm proximal and distal to colorectal cancer margins in 37 patients. The DNA ploidy and proliferative pattern of each sample were determined using flow cytometry. In 11 patients, histology of mucosal sections from the same sites also was analyzed. We found a higher frequency of aneuploidy than previously reported in mucosa up to 10 cm from a colorectal cancer; 62% (23/37) of the primary cancers were aneuploid, and of these, 48% (11/23) were associated with adjacent aneuploid mucosa. The mucosa adjacent to the 14 diploid cancers had only diploid characteristics. The proliferative activity (as reflected by synthetic (S) phase fraction) of aneuploid cancers (21.1 +/- 2.0% SEM) and aneuploid mucosa as far as 10 cm away (21.2 +/- 2.1% SEM) was higher than in normal controls (10.2 +/- 0.7% SEM) (P less than 0.0005). Parallel cytology excluded shed cancer cells as an explanation for these findings. Histology showed diffuse, generally mild and reactive, mucosal abnormalities in eight of 11 patients. Ploidy did not correlate with histologic abnormalities. The findings of aneuploidy and high S-phase fraction in uninvolved superficial mucosa provide evidence for a field defect in mucosa adjacent to colorectal cancer and support the concept that the large bowel mucosa behaves as a unit in carcinogenesis.

Adult↗
PubMed1990

The surgical treatment of squamous cell carcinoma of the oesophagus in Singapore.

In a retrospective study, we reviewed 97 consecutive cases of squamous cell carcinoma collected over a five-year period (1978-1983). Resection of the tumour was possible in 30 out of 40 patients subjected to surgery. Of these 30 patients, five died within 30 days of surgery. Eight patients who underwent oesophageal resection were still alive after five years and apparently cured. Bypass surgery for unresectable lesions in six patients were complicated by anastomotic leakage in three patients. Patients unsuitable for surgical resection were treated using Celestin tube insertion or radiation. Mean survival in 13 patients with Celestin tube insertion was 4.1 months. Of 48 patients who were treated by radiotherapy, two lived beyond five years. Surgical resection restores swallowing effectively and offers a 25% chance of cure and should be done in fit patients. In unfit patients with advanced disease, palliation from the use of radiotherapy and Celestin tube insertion were poor. Newer techniques such as endoscopic laser recanalisation and bicap hyperthermia may need to be considered for palliation in this group of patients.

Adult↗
PubMed1990

Screening for colorectal cancer in Singapore.

The incidence of colorectal cancer in Singapore has risen relentlessly since 1955. Today, the large bowel is the most frequent gastrointestinal cancer site among both men and women. Survival with this cancer has shown little improvement during this period. The prospects for further reduction in mortality through more radical surgery, adjuvant radiotherapy, chemo- or immunotherapy remain limited. Theoretically, detection of colorectal cancer at an earlier stage or detection of its precursors will reduce mortality. Screening for colorectal cancer is advocated to achieve this end. Success with screening programmes will depend on the diffusion of current knowledge about this disease to both health professionals and the general public.

Colonoscopy↗