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Biomedical subjects

R Nambiar

Publications and source records attributed to R Nambiar.

At least 19 recordsLinked to original sources
PubMed2003

Particle transport in asymmetric scanning-line optical tweezers.

We describe a scanning-line optical tweezing technique with an asymmetric beam profile in the back focal plane of the microscope objective. The motion of a trapped particle along the scan line is studied as a function of beam asymmetry, and it is shown that this technique can be used to exert a constant lateral force on the particle, realizing purely optical constant-force tweezing. The observed effect is attributed in a geometric optics model to a non-zero lateral component of the scattering force.

Biophysical Phenomena↗
PubMed2000

Pertussis antibody levels in infants immunized with an acellular pertussis component vaccine, measured using whole-cell pertussis ELISA.

A commercially available whole-cell pertussis IgG ELISA was used to test the response of 137 2-month-old infants to immunization with a trivalent acellular pertussis vaccine. The pre-immunization geometric mean (GM) IgG index was 6.96 (95% confidence interval (CI) 5.88-8.04) and the postimmunization GM index was 13.16 (95% CI 12. 20-14.11), P < 0.001. Eighty percent of subjects (110/137) had a significant 1.5-fold increase of pertussis IgG index (97/137, 71%) or a postimmunization IgG index > 10 (93/137, 68%). In single antigen ELISA, 83% showed at least a fourfold increase in pertussis toxin-specific IgG (PT-IgG) and 91% showed an increase in IgG specific for filamentous haemagglutinin (FHA-IgG). Four percent had high pre- immunization antibody levels (index > 20), likely to reflect recent maternal exposure to pertussis. This correlated with a smaller increase in pertussis IgG index. A decline in pertussis IgG index postimmunization occurred in 17/24 infants (71%) whose pre-immunization IgG index was > 10. This postimmunization pertussis IgG index was not significantly different to that of infants with a low pre-immunization index. A similar trend was noted with PT-IgG and FHA-IgG results. The whole-cell ELISA can detect a response to acellular pertussis vaccination in most infants if both antibody index and degree of seroconversion are calculated and at least one criterion is satisfied.

Antibodies, Bacterial↗
PubMed1996

Gastric cancers in Singapore: poor prognosis arising from late presentation.

BACKGROUND: Mortality rates from gastric cancer, apart from those derived from Japanese series, remain poor. This paper sought to determine the present outcome of gastric carcinoma in a predominantly Chinese population in Singapore. Prognostic factors useful in predicting survival were also evaluated in this population. METHOD: All cases of histologically confirmed gastric adenocarcinoma presenting in 1992 were entered into a prospective database. Prognostic factors related to age, sex, site of disease, depth of invasion, histological grade, nodal status and stage of disease were evaluated in patients with resectable disease to determine their utility in predicting survival. RESULTS: Of 131 consecutive patients with histologically proven adenocarcinomas, 37% had distant metastases at presentation predominantly in the liver (21%) and peritoneal cavity (20%). Sixty-four per cent of patients underwent surgery and in only 51% of these patients was resection of the tumour possible. Stages III and IV (T4N2) locally advanced disease were present in 38% of patients. Thus the majority of patients presented with late or metastatic disease (75%, stages III and IV). Sixty per cent of patients were alive at 1 year and 40% at 2 years after resection of the tumour (Kaplan-Meier survival plots). In contrast, no patient survived longer than a year if the tumour was not resectable (P < 0.001, log-rank test). Median survival of patients without surgery was 12 weeks. Median survival for patients with resected stage IV disease was 23 weeks, compared to 18 weeks after surgical bypass. Age, sex, site, depth of invasion and histological grade did not significantly predict survival. Patients with node-negative disease survived longer (2 years. 70%) than those with nodal involvement (2 years, 44%: P = 0.06, log-rank test). Pathologic staging with the TNM system was useful in predicting survival (P < 0.001). Sixty per cent of patients with stage I and II disease were alive at 2 years compared to 54% with stage III disease and 0% with stage IV disease. CONCLUSION: The prognosis of stomach cancer remains poor, due predominantly to late presentation. Pathologic TNM staging and nodal status were useful in predicting survival outcome after resection. If the tumour were resectable, survival was appreciable even in patients with advanced stage III (2 years. 54%) and stage IV (1 year, 40%) disease. Strategies to improve outcome should focus on early detection of gastric carcinomas.

Adult↗
PubMed1996

Difficulty of obtaining wide tumour to deep fascial margins in Asian women with breast cancers: implications on treatment and prognosis.

This prospective study sought to determine the width of tumour to fascial margins attainable after mastectomy in Asian women with breast cancers. The narrowest perpendicular distance from tumour to the deep fascia was measured in the mastectomy specimens of 177 consecutive Singaporean women with primary breast carcinomas. A highly significant linear correlation was present between the tumour size (P < 0.001, Pearson's R = -0.34) and the width of deep margins. Furthermore, T staging (P < 0.01, ANOVA) was inversely correlated with the width of deep margins and significant differences were observed between early (T0 to T2) and late (T3 to T4) lesions. In patients with ductal carcinoma in situ (DCIS) and T1 lesions, deep margins greater than 10 mm were achieved in only 23% and 33% of the women respectively. For patients with DCIS, 33% had either positive margins or margins less than 2 mm. The corresponding figures for women with T1 and T2 lesions were 11% and 26%, respectively. The inability to obtain negative deep margins were considerable with large tumours as 10% of the women with T3 tumours and 33% with T4 tumours had positive margins. Thus the proportion of positive or narrow deep margins following mastectomy is appreciable in Asian women and even in those with early tumours. The implications of these findings on the risk of locoregional recurrence or the need for more radical surgery or adjuvant radiotherapy remain uncertain, and will require further elucidation.

Adult↗
PubMed1995

Resection and anastomosis of obstructed left colonic cancer: primary or staged?

A retrospective analysis of the treatment of 70 patients with obstructed left colonic cancer was undertaken in order to assess whether staged or primary resection was more appropriate. Thirty-four patients had initial colostomy and staged resection (group 1) while 36 patients were treated by primary resection and immediate anastomosis following intra-operative bowel washout (group 2). There were seven deaths (10%), five in group 1 and two in group 2. The wound infection rate and average hospital stay were 44% and 36 days in group 1 and 19.4% and 16.5 days in group 2, respectively. Twenty per cent of patients in group 1 did not complete their staged procedures and had to live with their colostomies. The smoother postoperative recovery and shorter hospital stay was particularly significant in group 2 patients. As primary resection and anastomosis can now be performed with relative safety and reduced morbidity, we conclude that staged procedures can no longer be accepted as standard treatment for left colonic obstruction.

Anastomosis, Surgical↗
PubMed1995

The effect of recombinant growth hormone on nitrogen balance in malnourished patients after major abdominal surgery.

The effect of recombinant growth hormone (rGH) on nitrogen balance was studied in malnourished patients receiving total parenteral nutrition after major abdominal surgery. Fifteen patients were randomized to receive either subcutaneous rGH (0.2 iu/kg) or placebo (saline) injection daily for seven days after surgery. Positive nitrogen balance was achieved throughout the treatment period with rGH administration and was significant on days 3 and 6. This was associated with increase in mid-arm muscle circumference and significant weight gain. Plasma insulin-like growth factor-1 (IGF-1) concentration was significantly raised in the rGH group at day 7, suggesting its role in the anabolic effect of growth hormone. Plasma pre-albumin and retinol-binding protein concentrations were raised in both the rGH and control groups, indicating improvement in the nutritional status. We conclude that the postoperative catabolic response can be attenuated using recombinant growth hormone.

Abdomen↗
PubMed1995

Malignant melanoma of the oesophagus--a case report.

Primary malignant melanoma of the oesophagus is a rare presentation for melanoma and is also an unusual and aggressive form of oesophageal neoplasm. We present a 57-year-old Chinese gentleman who underwent successful resection of a primary malignant melanoma of the oesophagus.

Diagnosis, Differential↗
PubMed1992

Splenic abscess.

Isolated splenic abscess is an uncommon condition. Seven cases seen between 1980 and 1990 are reviewed. The clinical presentation is non-specific and diagnosis is usually delayed. Computerized tomography allowed for accurate diagnosis in all cases. Pseudomonas species as a causative organism is reported to be rare, but were present in three of the present cases. Antibiotic therapy alone is insufficient and splenectomy remains the treatment of choice.

Abscess↗
PubMed1992

Prevalence of protein calorie malnutrition in general surgical patients.

The prevalence of protein calorie malnutrition (PCM) based on ten nutritional parameters was studied in 307 patients undergoing major elective surgical operations. These parameters included anthropometric measurements (weight/height, triceps skin fold thickness, arm muscle circumference) and biochemical (serum total proteins, albumin, transferrin, prealbumin, retinol binding protein) and immunological tests (total lymphocyte count and delayed hypersensitivity test). Using these criteria, the prevalence of PCM was high. Eighty-six percent of patients had at least one abnormal parameter. The prevalence of PCM as judged by weight/height and arm muscle circumference was 49% and 62% respectively. The incidence was higher in cancer than non cancer patients (63% vs 43%). Although serum albumin and total protein levels were normal in 93.5% of patients, acute serum protein markers such as transferrin, prealbumin and retinol binding protein were low in 20-30%. Lymphopenia of 1500 cells/cu mm or less was found in 18% and abnormal delayed hypersensitivity test in 60%. We found that only weight/height, serum protein, transferrin and lymphopenia had predictive values in postoperative morbidity and mortality. By identifying PCM patients early, adequate nutritional support can be given in order to reduce the risk of major surgical complications.

Adolescent↗
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

Palliative gastrojejunostomy for advanced carcinoma of the stomach.

The outcome of 51 patients who underwent gastrojejunostomy for unresectable gastric cancer with outlet obstruction was studied to evaluate the palliative benefit. The operative mortality and postoperative complication rates were 22% and 55% respectively. The mean duration of postoperative hospital stay was 13 days and median survival period 14 weeks. Delayed gastric emptying occurred in 21%, mostly in patients with extensive tumour involvement of the stomach and was associated with a poor outcome. Among the survivors, 87.5% were able to take a soft diet by the eighth postoperative day and 60% could cope with the progression of the disease at home. We conclude that gastrojejunostomy offers satisfactory palliation in patients with advanced gastric cancer.

Adult↗
PubMed1991

Malignant axillary lymphadenopathy--a problem for management.

Axillary lymph node enlargement can be the first and only manifestation of malignancy. Although lymphoma and metastasis from melanoma, breast and lung cancers are known causes, the primary tumour may remain undetected in some cases despite exhaustive investigations. Therefore, once the diagnosis of malignancy is confirmed by clinical examination followed by histology, further investigations should be limited to a search for treatable malignancies only. Extensive investigations with a hope of discovering the primary is useless and not cost effective. Close follow up may occasionally reveal new clinical signs when further investigations can be justified. This paper reports the clinical approach to diagnosis and management of such cases with examples of illustrative cases.

Adult↗
PubMed1991

Leiomyoma of the oesophagus.

Leiomyoma of the oesophagus is an uncommon lesion but should be considered in the differential diagnosis of younger patients presenting with dysphagia or mediastinal mass. This report deals with the management of 14 cases of leiomyoma seen during a 12 year period.

Adult↗
PubMed1990

Impact of fine needle aspiration cytology on the management of solitary thyroid nodules.

To evaluate the impact of the routine use of fine needle aspiration cytology (FNAC) on the management of solitary thyroid nodules, 102 consecutive patients were assessed in regard to the proportion of patients being subjected to surgery and the corresponding yield of malignancy. This cohort was compared with a historical control where FNAC was not routinely applied as a diagnostic selection criterion. The percentage of patients operated on had decreased from 95% to 60% (P less than 0.001) without any significant decrease in the field of malignancy: 18.6% vs 17.6% (P = 0.97). The yield of malignancy of patients operated on had increased from 18.4% to 26.2%. Of those not subjected to surgery, 14 patients or 14% of the original cohort experienced spontaneous complete resolution of their nodules after a mean follow-up period of 5.5 months (s.d. = 3.5) (non-resected group). In the retrospective evaluation of diagnostic discriminants to maximize yield of malignancy while minimizing unnecessary surgery for thyroid nodules, the use of combined parameters of clinical suspicion, positive FNAC and age greater than or equal to 50 years detected 100% of malignancies with only 50% of patients requiring surgery. This was superior to other modalities including clinical parameters and expensive investigations of radionuclide scans and ultrasonography. In conclusion, the use of FNAC in the evaluation of solitary thyroid nodules has resulted in a decreased proportion of patients requiring surgery and cost saving while maintaining the yield of malignancy.

Adolescent↗