Longitudinal micro-ultrasound assessment of the ob/ob mouse model: evaluation of cardiovascular, renal and hepatic parameters.

BACKGROUND/OBJECTIVES: Obesity is reaching epidemic proportions and is associated with increased risk factors for cardiovascular disease. Leptin-deficient mice (ob/ob) are widely employed to investigate obesity. Aim of this study was to provide a micro-ultrasound (µUS) longitudinal evaluation of the ob/ob mouse model in terms of cardiovascular effects, consequences for renal microcirculation and liver fat accumulation. SUBJECTS/METHODS: Sixteen wild-type (wt) and eleven ob/ob male mice were studied at 8 (T0) and 25 (T1) weeks of age with a µUS system (Vevo2100) and B-mode and Doppler images were acquired. Cardiac output (CO), ejection fraction (EF), stroke volume (SV), fractional shortening (FS) and E/A ratio were measured from cardiac images. Mean diameter (Dmabd, Dmcar), relative distension (relDabd and relDcar) and pulse wave velocity (PWVabd and PWVcar) were obtained for both abdominal aorta and common carotid. As regards renal microcirculation, renal resistivity and pulsatility index (RI and PI) were assessed. The ratio between grey levels related to liver and kidney (Steato-Score) was used as index of hepatic steatosis. RESULTS: At T0, ob/ob mice showed reduced SV, EF, CO and relDabd values and increased LVmass, PWVabd, RI, PI and Steato-score measurements. The same comparison repeated at T1 highlighted similar results for SV, EF, CO, RI, PI and Steato-Score; furthermore, obese mice showed reduced Dmabd and Dmcar measurements in comparison with lean controls. The longitudinal analysis showed an increase in LVmass and Dmabd and a reduction of FS, EF, CO, relDabd and relDcar for wt animals, while no differences were found for the ob/ob group. CONCLUSIONS: ob/ob mice presented a premature cardiac dysfunction without a further age-related deterioration and a reduction in the abdominal aorta and carotid artery mean diameter in adult age. The proposed analysis can represent a valid approach for longitudinal studies aimed at testing new therapeutic strategies or for characterizing other mouse models.

Effects of intracellular pH and Ca2+ on the activity of stretch-sensitive cation channels in leech neurons.

The effects of intracellular pH and calcium on the activity of the leech mechanosensitive cation channels have been studied. These channels exhibited two activity modes denoted as spike-like (SL) and multiconductance (MC). In the absence of mechanical stimulation, acidification of the intracellular side of membrane patches from 7.2 to 6.2 reversibly increased the mean channel open time as well as the opening frequency in the SL mode. Channels in MC mode were activated by a pH(i) reduction from 7.2 to 6.2, but were inhibited at pH(i) 5.5. Unlike MC mode, SL mode was strongly activated by intracellular Ca(2+). Fura-2 imaging experiments showed that intracellular calcium was induced to increase by hypotonic cell swelling. The major component of this response did not require extracellular calcium. A component of the swelling-induced calcium response was sensitive to blockers of stretch-sensitive cation channels. The results indicate that the two activity modes of mechanosensitive channels of leech neurons respond differently to changes of intracellular pH and calcium. The sensitivity of the channel to micromolar concentrations of internal free calcium, along with its permeability to this ion, is consistent with a role in the amplification of mechanically induced Ca(2+) signals in leech neurons.

[Diagnostic of congenital syphilis: a comparison between serological tests in mothers and their newborns]. / Diagnóstico de sífilis congênita: comparação entre testes sorológicos na mãe e no recém-nascido.

For the purpose of establishing the incidence of maternal and congenital syphilis among pregnant women at delivery and their respective newborns, a study was carried out to determine treponemic and non-treponemic serology in one thousand (1,000) parturient women and their children at Santa Marcelina Hospital - São Paulo, between June 95 and July 96. All blood samples (maternal venous, umbilical cord and newborn venous) were VDRL-tested, treponemic tests (TPHA, ELISA IgG, ELISA IgM) being applied whenever one of the samples from mother or newborn proved positive. Further, an anti-HIV search was run through ELISA among VDRL-positive mothers. Among the 1,000 parturients, 24 (2.4%) were found to be VDRL-reactive; 18 (1.8%) newborn children of these 24 mothers presented positive serology in their umbilical cord blood and 19 (1.9%) in venous blood. No positive newborns were found for negative mothers. From the high occurrence of maternal and congenital syphilis in this group of patients, we propose a VDRL maternal test as a way of selecting gestational and congenital syphilis cases, since this test appeared to be sufficiently capable of such diagnoses. Of the treponemic tests, the ELISA test did not enhance diagnostic sensitivity.

The torsion meter: a critical review.

The purpose of this study was to determine how effectively the torsion meter measures vertebral rotation. Nine thoracic vertebrae from three disarticulated spines were individually rotated through an arc of 0-60 degrees and measured with a torsion meter by three investigators. One hundred forty-four errors were made in the 351 measurements, of which greater than 92% were within +/- 5 degrees. We concluded that use of the torsion meter is an effective way to measure vertebral rotation.