K-ras mutation in colorectal carcinomas from singapore

54 sporadic colorectal cancers were analyzed for aberrations in the K-ras oncogene. DNA was extracted from frozen tissues obtained from surgical resection and analyzed for mutations in codons 12, 13 and 61 of the K-ras oncogene using single strand conformation polymorphism analysis (SSCP) and direct sequencing. Point mutations in the K-ras oncogene were found in 26/54 (48%) cases, all of which resulted in amino acid substitutions. No other types of mutations (e.g. insertions or deletions) were found. 4 of the mutations were at codon 12, 22 in codon 13 and only 1 was a codon 61 mutant. G-->A transitions were found to be predominant. A remarkable finding was the high preponderance of (13)Gly-(13)Ser mutations (54%). No correlation was observed between K-ras mutations and tumor location, Dukes' stage, differentiation levels, age or sex of the patient.     

Vitamin A-sensitive tissues in transgenic mice expressing high levels of human cellular retinol-binding protein type I are not altered phenotypically.

The suggested function of cellular retinol-binding protein type I [CRBP(I)] is to carry retinol to esterifying or oxidizing enzymes. The retinyl esters are used in storage or transport, whereas oxidized forms such as all-trans or 9-cis retinoic acid are metabolites used in the mechanism of action of vitamin A. Thus, high expression of human CRBP(I) [hCRBP(I)] in transgenic mice might be expected to increase the production of retinoic acid in tissues, thereby inducing a phenotype resembling vitamin A toxicity. Alternatively, a vitamin A-deficient phenotype could also be envisioned as a result of an increased accumulation of vitamin A in storage cells induced by a high hCRBP(I) level. Signs of vitamin A toxicity or deficiency were therefore examined in tissues from transgenic mice with ectopic expression of hCRBP(I). Testis and intestine, the tissues with the highest expression of the transgene, showed normal gross morphology. Similarly, no abnormalities were observed in other tissues known to be sensitive to vitamin A status such as cornea and retina, and the epithelia in the cervix, trachea and skin. Furthermore, hematologic variables known to be influenced by vitamin A status such as the hemoglobin concentration, hematocrits and the number of red blood cells were within normal ranges in the transgenic mice. In conclusion, these transgenic mice have normal function of vitamin A despite high expression of hCRBP(I) in several tissues.     

Neutropenia with fever

CAUSAL GERMS: Over the last 10 years, hemotology units have seen many changes in the epidemiological pattern of infections in neutropenic patients, with a growing number of infections caused by Gram-positive germs. The number of septicemias due to multiresistant Gram-negative germs (Pseudomonas aeruginosa, Strenotrophomonas maltophilia) has however remained high. IMPACT OF THERAPEUTIC REGIMENS: Improved prognosis in neutropenic patients depends for a large part on careful management of septic episodes. As the risk of septicemia is strongly correlated with the degree of efficacy of antibiotic regimens, susceptibility data must always be examined when developing antibiotic protocols in units caring for neutropenic patients.     

Exophthalmos and blindness disclosing an ethmoidal-maxillary malignant non-Hodgkin's T-cell lymphoma. Apropos of a case]

BACKGROUND: We report a case of non-Hodgkin's malignant lymphoma of the cervicofacial region revealed by unilateral exophthalmos and blindness, an unusual mode of expression. CASE REPORT: A 40-year-old man with a 4-month history of diabetes mellitus had suffered from exophthalmos and blindness of the right eye for 20 years. Physical examination showed a homolateral hemifacial tumefaction and ophthalmoplegia. The right ocular fundus showed papillar edema and non-proliferative diabetic retinopathy. The left eye was normal. The otolaryngology explorations revealed a voluminous tumor in the anterior nasal cavity and in the cavum. Two biopsies were performed. Histology reported non-Hodgkin's T-cell lymphoma. Orbitocerebral and cervicofacial computed tomography visualized the aggressive ethmoidomaxillary extension with intraorbital and intracranial involvement. Chemotherapy (CHOP) combined with radiotherapy led to tumor regression and involution of the exophthalmos. Diagnostic difficulties, management and prognosis are discussed.     

Pseudo-tumoral osteomyelitis. Immunologic study and etiopathogenic approach. Apropos of 2 cases]

Two cases of pseudo-tumoral osteomyelitis are reported. The first concerns a 12 year-old boy who presented with pain of the left knee during 8 months and, later on, with swelling of the upper extremity of the left leg, without fever or local inflammatory signs. The radiological aspect of condensation with a filling defect and "chimney" crossing the cartilage led to osteotomy. Local bacteriological samplings were normal. The second case concerns a 11 year-old boy who, after having complained from pain of the right wrist during 2 weeks, presented with swelling and on X-ray films a picture of metaphyso-epiphyseal lysis and an aspect of sequestrum in its center. There was no biological sign of inflammation. Evolution was favorable after antibiotic treatment and immobilization. In both cases, an immunological study showed an activation syndrome of the immune system with increased serum IL-1, IL-2 receptors and class II antigen receptors on the surface of T cells, suggesting a previous immunization of both children towards staphylococcus and, thereby, the subacute nature of evolution.     

Nosocomial outbreak of acute gastroenteritis in a neonatal intensive care unit in tunisia caused by multiply drug resistantSalmonella wien producing SHV-2 beta-lactamase

In a Tunisian hospital 27 babies, including 12 who were premature, in a single intensive care unit suffered acute gastroenteritis in the period from January to May 1988. The mean age at the onset of gastroenteritis was 8.4 days; nine babies died.Salmonella wien was isolated from stools (all babies) and blood (4 babies). It was also isolated from the stools of one nurse and from a mattress. Twelve of the babies had received cefotaxime, which was successfully replaced by oral colimycin. The outbreak was stopped by the implementation of infection control measures. All isolates ofSalmonella wien were of the same biotype, and had the same antibiotic resistance pattern (third generation cephalosporins, monobactams, aminoglycosides, chloramphenicol, trimethoprim and sulphonamides) and plasmid DNA restriction pattern. The isolates were all susceptible to a combination of cefotaxime and clavulanic acid (a -lactamase inhibitor), which displayed synergy, suggesting the presence of a -lactamase (geometric mean MICs 11.24 µg/ml for cefotaxime alone and 0.24 µg/ml in combination with 0.1 µg/ml potassium clavulanate). All isolates produced TEM-1 and SHV-2 -lactamase which was not transferable toEscherichia coli by conjugation. The presence of the SHV-2 enzyme inSalmonella wien may allow it to adapt to newer -lactams which is a cause for concern in this hospital.