Evaluation of Mycotube, a modified version of Lowenstein-Jensen (LJ) medium, for efficient recovery of Mycobacterium tuberculosis (MTB).

Timely diagnosis of tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB), is only achieved for ~58% cases. An improved, accurate, time- and cost-effective method for bacteriological confirmation of MTB is necessary. We evaluated Mycotube, a new variant of Lowenstein-Jensen (LJ) culture medium, by comparing it with Mycobacterium Growth Indicator Tube (MGIT) 960 (gold standard), local LJ, and bioMérieux LJ-T in terms of isolation rate and time-to-growth. Pulmonary and extra-pulmonary samples from treatment-naïve suspects (n = 207) were decontaminated by the N-acetyl-L-cysteine-sodium hydroxide method and used to inoculate the four media. Subjective and objective parameters were used for evaluation. Mycotube yielded 140 positive results, compared to 162, 69, and 141 from MGIT, local LJ, and LJ-T, respectively. Of these, 139 (67%) were true-positive results and 1 (0.5%) was false-positive. The mean time-to-growth detection was 17.4 days for Mycotube, compared to 14.5, 28.1, and 16.5 days for MGIT, local LJ, and LJ-T, respectively. The mean time-to-growth for local LJ significantly differed from that for MGIT, but not those for LJ-T and Mycotube. No contamination was observed. Mycotube had a sensitivity of 85.8% and a specificity of 97.8% as compared to MGIT. Mycotube offers good results, comparable with those observed for conventional LJ. It requires only basic laboratory infrastructure. The overall cost of the test should be nearly three times lower than that of MGIT. Mycotube helps with TB diagnosis and generates pure isolates for drug susceptibility testing.

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.

Breast conservation therapy--surgical aspects.

Breast conservation therapy is now accepted as an alternative to mastectomy for early stage breast cancer. In 1991 the NIH recommended a regime consisting of the excision of a primary tumour with a 1 cm-margin of breast tissue around and an axillary node dissection followed by postoperative administration of 45-50 Gy irradiation. Although this regime is popular in most centres, several issues remain controversial. These are (1) selection of cases, (2) surgical technique, (3) histopathology and radiology, and (4) adjutant therapy. In this presentation I shall deal mainly with the surgical aspects of breast conservation.

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.

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.

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.

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.

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.

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.

General surgery in an era of superspecialisation--what is the future?

The present century has seen extraordinary scientific advances and enormous social changes unparalleled in all medical history. Of these, specialisation and superspecialisation are significant developments that have made major impact on the practice of surgery. While specialisation is intended to improve the quality of care, excessive specialisation resulting in separation into narrow areas can have a deleterious effect on the total care of the patient, teaching, training and surgical research. General Surgery which is the foundation of surgical practice has been affected more than any other in this process and the problem has received world wide attention. General Surgery is a broad speciality responsible for the care of the surgical patient as a whole including diagnosis, preoperative, operative and postoperative management of all common surgical conditions. In addition, it requires the special expertise to manage the surgical problems of the alimentary tract, abdomen, endocrines, vascular and head and neck and comprehensive care of trauma and critical care. The general surgeon will continue to play a major role in future to suit the changing trends in surgical practice especially with the recent advances in endoscopic and laparoscopic surgery. The general surgeon of the future should continue to have a broad based training, be knowledgeable in basic sciences and responsible for total care of the patient and at the same time, have a special interest and expertise in subspecialty. General Surgery should continue to provide the basic training for all specialties, foster basic and clinical research and provide a solid foundation for all surgical trainees and above all continue the leadership role in the teaching of undergraduate students.

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.

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.

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.

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.