Ultrastructural study of a retinoma by intraocular fine-needle aspiration biopsy

The authors present the results of a transmission electron-microscopic study performed on a tissue sample obtained by an intraocular fine-needle aspiration biopsy in a case of retinoma. The ultrastructural study showed that the tumor was composed mainly of granular osmiophilic material which contained some tumor cells. These cells showed peculiar ultrastructural characteristics, which demonstrated their neural character, and appeared in different degenerative stages. Apparently, this is the first case in whom ultrastructural technique have been applied to study an intraocular tumor sample obtained by intraocular fine-needle aspiration biopsy, and the first case of retinoma studied by such a diagnostic approach.     

Damage and mutagenesis of bacteriophage lambda induced by high pH.

Bacteriophage lambda-Escherichia coli complexes exhibited remarkable sensitivity to alkaline pH 10.0 at 37 degrees C. The decline in plaque forming units after alkali treatment was more pronounced in complexes with some of the radiation repair defective mutants of E. coli K-12, i.e. uvrArecA, recA, rer and lexA mutants as compared to those of uvrA, recB and wild-type strains. The red gene of lambda phage and recA gene of E. coli seem to have a complementary effect on the alkali induced lesions. Alkaline treatment to lysogenic lambda phage was also found to be mutagenic. An enhanced level of mutagenesis was observed when treated phage particles were allowed to adsorb on treated wild-type bacteria. Moreover, the alkali treatment to lysogen (lambda cI857-E. coli) resulted in prophage induction in nutrient broth even at 32 degrees C. Thus on the basis of these results the role of error prone SOS repair systems in the repair of alkali induced lesions in lysogenic bacteriophage lambda has been suggested.     

Role of protein kinase C in the modulation of multidrug resistance: expression of the atypical gamma isoform of protein kinase C does not confer increased resistance to doxorubicin.

Cross-resistance to anticancer drugs, termed multidrug resistance (MDR), is functionally associated with the expression of a plasma membrane, energy-dependent, drug efflux pump termed P-glycoprotein (PGP), the product of the mdr1 gene. We have shown previously that MCF-7 breast carcinoma cells transfected with the human mdr1 gene (BC-19 cells) exhibit greater MDR when stably transfected with protein kinase C alpha (PKC alpha). We now demonstrate that transfection of BC-19 cells with the gamma isoform of PKC (BC-19/PKC gamma cells), which is not normally present in BC-19 cells, does not confer increased resistance to doxorubicin, despite a 19-fold increase in PKC activity. All of the increased PKC activity is accounted for by PKC gamma and it is rapidly down-regulated by phorbol dibutyrate, within 15 min of treatment. Endogenous PKC alpha and PKC epsilon activities are not affected by phorbol dibutyrate. The cytotoxicity of doxorubicin was similar in BC-19/neo or BC-19/PKC gamma cells after either 2-hr or continuous drug exposure, and co-treatment with phorbol dibutyrate increased resistance to doxorubicin 4-fold in both cell lines. Phosphorylation of PGP was similar in both cell lines and drug accumulation was not affected by overexpression of PKC gamma. These results demonstrate that transfection of PGP-expressing cells with an atypical isoform of PKC does not confer increased MDR, and they suggest that the regulation of PGP is phenotype specific with respect to the isoform of PKC.     

Duodenogastric reflux after choledochoduodenostomy

Duodenogastric reflux (DGR) has been implicated in several disease processes. The present study was carried out to document the incidence and evaluate the clinical significance of DGR after choledochoduodenostomy (CDD). A total of 13 patients who had undergone cholecystectomy with a standard side-to-side CDD for choledocholithiasis or chronic pancreatitis were studied by symptom evaluation, scintigraphy, endoscopy, and gastric mucosal histology at least 6 months after surgery. The scintigraphic findings were then compared with those of 10 patients who had undergone cholecystectomy alone. Only two patients (15%) had mild dyspeptic symptoms. The incidence of DGR after CDD was 69% compared to 20% in the cholecystectomy alone group (P < 0.05). In the majority of patients the DGR was only mild to moderate and the severity correlated well with the degree of endoscopic gastritis, but not with the clinical symptoms or histological findings. These results indicate that while CDD is associated with a high incidence of DGR, its occurrence does not produce significant clinical symptoms.     

Ventrally emigrating neural tube cells migrate into the developing vestibulocochlear nerve and otic vesicle

Virtually all cell types in the inner ear develop from the cells of the otic vesicle. The otic vesicle is formed by the invagination of non-neural ectodermal cells known as the otic placode. We investigated whether a recently described cell population, originating from the ventral part of the hindbrain neural tube known as the ventrally emigrating neural tube (VENT) cells, also contributes cells to the otic vesicle. The ventral hindbrain neural tube cells were labeled with the fluorescent vital dye DiI or replication-deficient retroviruses containing the LacZ gene in chick embryos on embryonic day 2, after the emigration of neural crest from this region. One day later, the labeled cells were detected only in the hindbrain neural tube. Shortly thereafter, the labeled cells began to appear in the eighth (vestibulocochlear) cranial nerve and otic vesicle. From embryonic day 3.5-5, the labeled cells were detected in the major derivatives of the otic vesicle, i.e. the endolymphatic duct, semicircular canals, utricle, saccule, cochlea, and vestibulocochlear ganglion. That the emigrated cells originated from the ventral part of the hindbrain neural tube was confirmed by focal application of DiI impregnated filter paper and with quail chimeras. It is concluded that, in addition to the otic placode cells, the otic vesicle also contains the ventrally emigrating neural tube cells, and that both cell populations contribute to the structures and cell types in the inner ear. It is well known that inductive signals from the hindbrain are required for the morphogenesis of the inner ear. The migration of the hindbrain neural tube cells into the otic vesicle raises the possibility that the inductive effect of the hindbrain might be mediated, at least in part, by the ventrally emigrating neural tube cells and that, therefore, a mechanism exists that involves cells rather than diffusible molecules only.     

Myocardial sestamibi single-photon emission tomography: Variations in reference values with gender, age and rest versus stress?

Reference data files support the evaluation of myocardial perfusion single-photon emission tomography (SPET). The aim of this study was to create a large reference data base for technetium-99m sestamibi SPET, age and gender matched to the general patient population. One hundred and twenty-eight healthy volunteers (76 males and 52 females) with a likelihood of coronary artery disease of less than 5% underwent rest and maximal exercise^99mTc-sestamibi SPET with a 2-day protocol and 180° elliptical rotation. The normalized activity values of^99mTc-sestamibi in the inferior wall differed significantly between men and women. Age variations were found for men in the anterior wall. Normalized activity values in all four walls were strikingly similar during rest and stress. Our results suggest that the use of reference files in^99mTc-sestamibi SPET requires a gender- and, for males, possibly an age-matched reference population. Different reference files at rest and during stress might not be necessary.     

Aetiology of neonatal septicaemia in Qatif, Saudi Arabia

Neonatal septicaemia (NNS) is a major cause of neonatal morbidity and mortality. Neonatal septicaemia was studied to determine the incidence, common bacterial aetiology and antibiotic susceptibility in Qatif Central Hospital, Saudi Arabia. Of 1,797 babies admitted into the unit over a 3 year period, 144 (8.0%) had documented neonatal septicaemia consisting of 94 (65%) late onset and 50 (35%) early onset septicaemia. The incidence was 8.2/1000 of the total live births in the hospital.

Gram negative bacteria were encountered in 66.2%, gram positive bacteria in 29.2% and Candida albicans in 4.4% of the case. Klebsiella spp., E. coli, and Pseudomonas accounted for 81.8 % of the gram negative while Staphylococcus epidermidis, Staphylococcus aureus and group B Beta haemolytic Streptococcus accounted for 73.9% of the gram positive bacteria.

Most of Gram negative bacteria had a high sensitivity to Aminoglycosides and third generation Cephalosporins. Coagulase negative staphylococci were frequently resistant to most antibiotics but always sensitive to Vancomycin. The overall mortality rate was 18.7%.