Introns and gene evolution

In one scenario of gene evolution, exon shuffling has a fundamental role in increasing gene diversity. As DNA sequences accumulate in the databases, the picture of the intron/exon structures of genes becomes more and more clear. We discuss in this review some features of this picture that suggest that introns have been present since the early stages of evolution, and that exon shuffling was a fundamental process in the construction of ancient as well as modern genes.     

Validity of a Brazilian version of the Older Americans Resources and Services (OARS) mental health screening questionnaire

A validity study of the Brazilian version of the 15-item Short Psychiatric Evaluation Schedule (SPES), included in the mental health assessment of Older Americans Resources and Services (OARS), designed to detect psychiatric disorders in the elderly, against the "caseness" criterion suggested by Cooper and Schwarz was carried out with a community sample, as part of a survey to study health and living conditions of the elderly in a large urban center of a developing country, S?o Paulo, Brazil. The screening questionnaire was completed by 292 subjects, and 91 were selected for the psychiatric interview. The validity coefficients were as follows: sensitivity 61%, specificity 89%, positive predictive value 66%, negative predictive value 87% and misclassification rate 18%. A discriminant analysis using a stepwise procedure was then applied to select the best item discriminators of the screening questionnaire. The best set of discrimination comprised six items leading to the following validity coefficients: sensitivity 82%, specificity 77%, positive predictive value 58%, negative predictive value 92% and misclassification rate 21%. The possible factors related to false positive and false negative responses on the screening are discussed.     

Laparoscopic findings in serosal eosinophilic gastroenteritis. Report of two cases

This report describes the laparoscopic features of two patients with serosal eosinophilic gastroenteritis. In one case only hyperemia of the peritoneal serosa was found. In the other the laparoscopic picture resembled peritoneal carcinomatosis. We show that laparoscopy and peritoneal biopsy may permit diagnosis of the disease without the need for laparotomy.     

Echo-guided percutaneous puncture: a safe and valuable therapeutic tool for amebic liver abscess

To clarify the therapeutic role of echo-guided percutaneous puncture (EPP) in management of amebic liver abscess, 20 patients (24 abscesses) received metronidazole plus EPP. Fluid was aspirated through Chiba needles under real-time sonographic guidance so as to reduce cavity size to less than 3 cm. Not more than two EPPs were necessary in the majority of cases and no complication followed the procedure. This scheme resulted in a shortening of time of both hospitalization (less than or equal to 20 days) and liver lesion healing as assessed by ultrasound (less than or equal to 4 months). It is concluded that EPP is a valuable and safe therapeutic tool for hepatic amebic abscess.     

Recombinant human interferon-alpha induced cytoreduction in chronic myelogenous leukemia

Summary Fourteen patients with Ph'-chromosome positive chronic myelogenous leukemia (CML) in first chronic phase were treated with recombinant interferon-_2c. Interferon-_2c 5 to 10×10⁶ units s.c. was given for 12 weeks as an induction therapy. Maintenance treatment consisted of interferon-_2c 5 × 10⁶ units twice weekly s.c.. Two patients (14%) attained a complete clinical remission and 6 (43%) a partial remission, 3 of whom developed progressive disease during maintenance therapy. A complete disappearance of Ph'-chromosome was achieved in 1 patient. All patients had a more than 45% initial decline of the leukocyte count. Four out of ten patients with an initially enlarged spleen demonstrated reduction in spleen size. Influenza-like symptoms, anorexia, nausea, weight loss and fatigue were common side effects. Interferon-alpha is active in CML but additional clinical investigations are warranted to assess more precisely the therapeutic value of the interferons in this disease.     

High-frequency mutations in a plasmid-encoded gas vesicle gene in Halobacterium halobium

Gas vesicle-deficient mutants of Halobacterium halobium arise spontaneously at high frequency (about 1%). The mutants are readily detected, forming translucent colonies on agar plates in contrast to opaque wild-type colonies. To investigate the mechanism of this mutation, we recently cloned a plasmid-encoded gas vesicle protein gene, gvpA, from H. halobium. In the wild-type NRC-1 strain the gvpA gene is encoded by a multicopy plasmid of approximately 150 kilobase pairs (kb). We have now characterized 18 gas vesicle-deficient mutants and 4 revertants by phenotypic and Southern hybridization analyses. Our results indicate that the mutants fall into three major classes. Class I mutants are partially gas vesicle-deficient (Vac(delta-)) and unstable, giving rise to completely gas vesicle-deficient (Vac(-)) derivatives and Vac(+) revertants at frequencies of 1-5%. The restriction map of the gvpA gene region in class I mutants is unchanged but the gene copy number is reduced compared to the Vac(+) strains. Class II mutants can be either Vac(delta-) or completely Vac(-) but are relatively stable. They contain insertion sequences within or upstream of the gvpA gene. A Vac(-) class II mutant, R1, contains the 1.3-kb insertion sequence, ISH3, within the gvpA gene, whereas four Vac(delta-) class II mutants contain other insertion sequences upstream of the gene. Class III mutants are stable Vac(-) derivatives of either the wild-type or class I mutants and have no detectable copies of the gvpA gene. Based on these results, we discuss the mechanisms of gas vesicle mutations in H. halobium.     

High resolution nuclear magnetic resonance imaging of the spinal cord in experimental demyelinating disease

Summary Chronic recurrent experimental allergic encephalomyelitis was induced in a strain 13 guinea pig by inoculation of isologous spinal cord homogenate. The spinal cord was obtained after perfusion with 4% paraformaldehyde and examined with nuclear magnetic resonance (NMR) imaging. Proton NMR spin echo images (repetition time: 3 s; echo times: 20 and 60 ms) were obtained from intact, isolated spinal cord in a 4.7 Tesla, 50 mm bore magnet. The slice thickness of the images was 380 m and the inplane resolution was 40×40 m. The images showed superficial areas of low signal intensity in the lateroventral regions of the white matter, in some instances with a seam of higher signal intensity. Neuropathologically, these abnormalities corresponded exactly to areas of demyelination. Control images did not show these abnormalities. The present high resolution imaging allowed a correlation between demyelination and abnormal NMR signals in a small laboratory animal with an inflammatory demyelinating disease.Supported by the Belgian Foundation of Medical Scientific Research (FGWO, grant 3.0096.86 and grant 3.0019.86), by the Institute for the promotion of Scientific Research in Industry and Agriculture (IWONL) and by the Scientic Research Planning Office of the Belgian Government (DPWB), contract no. 87/92-120     

Development of spinocerebellar afferents in the clawed toad, Xenopus laevis

The development of spinocerebellar projections in the clawed toad, Xenopus laevis, was studied with horseradish peroxidase as an anterograde and retrograde tracer. Early in development cells of origin of spinocerebellar projections were found, contralaterally, in or close to the medial motor column. In older tadpoles ipsilaterally projecting spinal neurons were also labeled from the cerebellum. These are virtually indistinguishable from the large primary motoneurons that occupy a very similar position in the spinal cord. Most of the labeled spinal cells were found in the thoracic spinal cord; they lie halfway between the brachial and lumbar secondary motor columns. Surprisingly, no primary spinocerebellar projection arising from dorsal root spinal ganglion cells could be demonstrated in X. laevis tadpoles and adult toads. Therefore, fibers in the cerebellum that were labeled anterogradely from the spinal cord can be expected to originate exclusively from the secondary spinocerebellar tract cells. These fibers appear to cross the cerebellum in or at the border of the granular layer. The present data suggest that in X. laevis early in the development of the cerebellum a distinct secondary spinocerebellar projection is already present, originating in neurons that can be compared with the "spinal border cells" in mammals. The relative sparseness of this secondary spinocerebellar projection and the apparent absence of primary spinocerebellar afferents probably indicate that spinocerebellar pathways are only of minor importance in X. laevis. The possibility remains, however, that the expansion of the secondary spinocerebellar pathway only starts when metamorphosis has been completed.     

Disk hypodensity and disk herniation

The authors report the case of a patient with a herniated lumbar disk and bacterial meningitis. CT scan showed central disk hypodensity at the hernia level, whilst full cytological and bacteriological study of the disk following surgery revealed no evidence of spondylodiscitis. The problem was thus that of consequences of "degenerative" events related to the herniation. Central or peripheral disk hypodensity must in no case be considered as specific of discitis when there is a concomitant disk herniation.     

Antihypertensive effect of canrenone in a model where endogenous ouabain-like factors are present

The effect of canrenone, an antialdosterone and partial ouabain-agonist drug, was studied in rats that developed volume expansion and hypertension after renal mass reduction and excess Na+ intake (RRM-salt). The RRM-salt was characterized by: (1) increased endogenous "digitalis-like" compounds in plasma [cross reactivity with digoxin-antibodies (57.5 +/- 5.0 vs. 42.1 +/- 3.8 pg/ml, p less than 0.02); inhibition of kidney Na+, K+-ATPase activity (135 +/- 5 vs. 154 +/- 5 mumol/mg/h, p less than 0.01); and inhibition of Na+ extrusion from normal erythrocytes (5.96 +/- 0.40 vs. 7.68 +/- 0.34 mmol/L cells/h, p less than 0.01)]; (2) reduced Na+, K+-pump activity (7.34 +/- 0.29 vs. 10.88 +/- 0.41 mmol/L cells/h, p less than 0.001) and increased Na+ content (4.66 +/- .08 vs. 4.16 +/- 0.11 mmol/L cells, p less than 0.01) in erythrocytes; and (3) low plasma renin activity (2.1 +/- 0.9 vs. 12.6 +/- 1.6 ng/ml/h). Ninety minutes after the administration to RRM-salt of a single oral dose of 60 mg/kg of canrenone, the systolic blood pressure decreased by 36 +/- 4 mm Hg (mean +/- SEM). Chronic canrenone administration (60 mg/kg/day) resulted in a marked antihypertensive effect associated to a correction of volume expansion, a decrease in endogenous "digitalis-like" compounds, and a partial recovery of Na+, K+-pump activity and Na+ content in erythrocytes. Our results suggest that the antihypertensive effect in RRM-salt rats results, at least in part, from antagonism with endogenous "digitalis-like" compounds.