The prognostic determinants of gastric cancer treatment outcome in Omani Arab patients

BACKGROUND: Gastric cancer is the most common cancer in Oman and a leading cause of cancer death. The variation in survival rates between countries and ethnic groups has been attributed to early detection policies, differences in clinicopathological features, treatment approaches, and biological characteristics. There were no previous reports on gastric cancer from Oman and very few studies on Asian Arabs. AIM: To evaluate the impact of clinicopathological and treatment variables on the survival prospects of Omani Arab patients diagnosed with gastric cancer. METHODS: The medical records of 339 Omani Arab patients diagnosed with invasive gastric adenocarcinoma during the period 1993-2004 were retrospectively reviewed. The relative importance of clinicopathological features and surgical and medical treatments were assessed using univariate and multivariate analyses. RESULTS: Most patients had distal ulcerating-type gastric cancer and presented at advanced stages. The median survival time for the entire cohort was 12 months (95% CI 9.7-14.4) with a 5-year overall survival rate of 16.7%. On univariate analysis of 237 patients who underwent surgical resection, the following positive prognostic factors emerged as significant: early overall TNM stage, early T stage, negative lymph nodes, tumor size <5 cm, ulcerating macroscopic appearance, and curative surgical attempt. The independent prognostic factors on multivariate analysis were T stage and lymph node involvement. CONCLUSION: The overall T and N stages are the most important determining factor for survival in Omani Arab patients. More efforts need to be made for the early detection of gastric cancer in developing countries such as Oman, while continuing to employ the standard surgical and medical treatments.     

The role of sialic acid in the activation of platelets by wheat germ agglutinin

Sialic acid is believed to play a critical role in the survival of blood platelets in circulation. Wheat germ agglutinin, which shows specificity for sialic acid, N-acetylglucosamine, and N- acetylgalactosamine, strongly activates platelets. The role of sialic acid in platelet activation by this lectin was studied utilizing neuraminidase-treated platelets and the succinylated lectin that has been reported not to recognize sialic acid. The succinylated lectin had a dimeric structure similar to the native lectin, but migrated more slowly in gel electrophoresis. The modified lectin bound to about 2.8 X 10(5) sites/cell, with an apparent dissociation constant of 2 microM compared to 5 X 10(5) sites/cell and a dissociation constant of 0.4 microM for the native lectin. The succinylated lectin neither aggregated nor agglutinated platelets, but agglutination of red cells in microtiter plates was normal. Aggregation of platelets by either wheat germ agglutinin or ristocetin was not affected by the succinylated lectin. Since the native wheat germ agglutinin is a strong activator of platelets and the succinylated derivative was devoid of all activity, it appears that a sialoprotein acts as the biologic receptor of wheat germ agglutinin in human platelets. This suggestion was strengthened by the observation that platelets treated with different concentrations of neuraminidase had a decreased capacity to bind this lectin. These platelets also showed reduced aggregation and serotonin secretion when activated with the native lectin. Since sialic acid has been implicated in the removal of platelets from circulation, wheat germ agglutinin may prove to be a useful tool to explore those clinical conditions in which platelet survival is shortened.     

Bone abnormalities of the knee: prevalence and significance at MR imaging

Focal abnormal signal intensity within the distal femoral condyles or proximal tibial plateaus is frequently seen on T1- or intermediate-weighted magnetic resonance (MR) images of the knee. To characterize the prevalence and significance of these findings better, a retrospective study of MR imaging of the knee, performed on the first 434 consecutive patients at a primarily outpatient community MR imaging center, was undertaken. A signal intensity loss demonstrated on images with a short echo time (20 or 25 msec) was divided into three types based on morphologic criteria. A type 1 finding was a diffuse, often reticulated signal intensity loss in the metaphyseal and epiphyseal regions of bone. A type 2 loss was associated with an interruption in the smooth, black cortical line. A type 3 finding was a profound signal intensity loss primarily restricted to the immediate subcortical region. Seventeen percent of all cases revealed a type 1 or 2 loss that may have been compatible with acute bone injuries. These bone lesions were frequently associated with tears of the anterior cruciate ligament and contralateral collateral ligament, but infrequently these lesions were detected with plain radiography and arthroscopy. When associated with a weight-bearing cortex, bone injuries detected with MR imaging may explain clinical symptoms of pain on weight bearing, and type 1 injuries may represent regions of bone at increased risk for the subsequent development of insufficiency fractures if the bone is not adequately protected during trabecular healing.     

Small hepatocellular carcinoma: intratumor ethanol treatment using new needle and guidance systems

Intratumor injection of absolute ethanol to treat small hepatocellular carcinoma sometimes results in incomplete necrosis of the tumor. Causes of this include inhomogeneous distribution of the ethanol and difficulty in identifying the tumor after previous ethanol injections. To solve these problems, the authors designed a multiple-side-hole needle for ethanol injection and implanted one or more small steel coils into the tumor before treatment to serve as a landmark. Six patients thus treated all showed adequate necrosis on follow-up computed tomography, biopsy, and angiography studies; initially elevated serum alpha-fetoprotein levels present in five patients were decreased. A resected surgical specimen obtained in one patient showed extensive necrosis of the tumor as well as of the surrounding healthy liver; only a small locus of equivocally viable cancer cells remained in the tumor margin.     

Stimulation of aldosterone secretion by metoclopramide in humans: Apparent independence of renal and pituitary mediation

Metoclopramide (MP), a dopamine antagonist, stimulates secretion of aldosterone by a mechanism which has not been defined. We examined a potential role for either the kidney or the pituitary to mediate MPs effect on aldosterone secretion. Responses to MP administered i.v. were measured in six anephric and six hypopituitary patients as well as in six normal subjects. MP increased the plasma aldosterone concentration (PAC) in normal subjects in a fashion similar to what had previously been reported. MP produced no increase in plasma levels of renin activity (PRA), cortisol, potassium, or sodium. Three of six anephric patients (all of whom had undetectable PRA) responded to MP with increases in PAC; the magnitude of these responses correlated with the plasma potassium concentration. All six hypopituitary patients showed increases in PAC after MP administration. MP increased plasma prolactin levels in normal subjects and anephric patients; one hypopituitary patient had high basal plasma prolactin levels which increased with MP. In conclusion, neither the kidney nor the pituitary is involved in the mechanism for MP stimulated aldosterone production. These observations suggest that MP may act on the adrenal to evoke secretion of aldosterone.