Compact high-sensitivity potentiometer for detection of low ion concentrations in liquids.

The compact potentiometer, based on an electronic circuit protected from electrostatic and electromagnetic interference, was developed for the measurement of low ion concentrations in liquids. The electronic circuit of the potentiometer, consisting of analogous and digital parts, enables the measurement of fA currents. This makes it possible to perform reliable measurements of ion concentrations in liquids that are as small as 10-8-10-7M. The instrument was tested using electrodes that were selective for tetraphenylphosphonium (TPP+) ions. It was demonstrated that the characteristic response time of the potentiometer electronic circuit to changes in the concentration of these ions in a liquid was in the order of 10 s. An investigation of TPP+ absorption by baker yeast has shown that this device can be successfully used for long term (several hours) measurements with zero signal drift, which was about 1 µV/s. Finally, due to the small dimensions of the electronic circuit (7.5 × 2 × 1.5 cm), this potentiometer can be easily installed at a large apparatus in the laboratory condition (≈25 °C), such as high pulsed electrical generators of magnetic fields that are used in electroporation studies of biological cells.

Early-stage cervical cancer: agreement between ultrasound and histopathological findings with regard to tumor size and extent of local disease.

OBJECTIVES: To determine the agreement between ultrasound and histological examination of the cervix in patients with early stage cervical cancer with regard to tumor size and local extent of the disease. METHODS: Eighteen patients with histologically proven cervical cancer Stage IB1-IIA according to traditional clinical staging (FIGO 1988) who were scheduled for radical surgery underwent a standardized transvaginal ultrasound examination. The maximum tumor length, anteroposterior tumor diameter, tumor width, tumor area, depth of cervical stroma invasion, and the minimal thickness of tumor-free cervical stroma on sagittal and transverse planes through the cervix were measured, and the local extent of the disease within the parametria and vagina were evaluated. The surgical specimens were examined using a specifically devised method of histopathological examination. The results of the ultrasound and histopathological examinations were compared. RESULTS: Limits of agreement were wide and the intraclass correlation coefficient (ICC) was low (0.51-0.58) for three of the four measurements taken to represent the minimal depth of tumor-free cervical stroma, i.e. the results of the measurements taken posteriorly and laterally. However, the limits of agreement were narrower and the ICC values were higher (0.74-0.92) for the depth of cervical stroma invasion and for the tumor size measurements. Histological examination revealed parametrial cancer infiltration in four patients, which was detected during ultrasound examination, with no false-positive results. CONCLUSIONS: Transvaginal sonography is acceptably accurate for evaluation of tumor size and depth of cervical stroma invasion in clinical practice.

Papular acrodermatitis of childhood: the Gianotti-Crosti syndrome.

Papular acrodermatitis of childhood (PAC), also known as Gianotti-Crosti syndrome, is a self-limited disorder with acute onset generalized lymphadenopathy and monomorphic lentil-sized, dense, nonconfluent, symmetric, flat-topped, non-pruritic papules. We describe 2 patients, one with anicteric hepatitis, lymphocytosis, and positive hepatitis B surface antigenemia, and the other with a cytomegalovirus (CMV) infection.