The Oklahoma Thrombotic Thrombocytopenic Purpura-haemolytic Uraemic Syndrome Registry. A model for clinical research, education and patient care.

The Oklahoma Thrombotic Thrombocytopenic Purpura-Haemolytic Uraemic Syndrome (TTP-HUS) Registry has a 24 year record of success for collaborative clinical research, education, and patient care. This article tells the story of how the Registry began and it describes the Registry's structure and function. The Registry provides a model for using a cohort of consecutive patients to investigate a rare disorder. Collaboration between Oklahoma, United States and Bern, Switzerland has been the basis for successful interpretation of Registry data. Registry data have provided new insights into the evaluation and management of TTP. Because recovery from acute episodes of TTP has been assumed to be complete, the increased prevalence of hypertension, diabetes, depression, and death documented by long-term follow-up was unexpected. Registry data have provided opportunities for projects for students and trainees, education of physicians and nurses, and also for patients themselves. During our follow-up, patients have also educated Registry investigators about problems that persist after recovery from an acute episode of TTP. Most important, Registry data have resulted in important improvements for patient care.

Torsion of pedunculated hepatocellular carcinoma. Report of a case in a young woman presenting with abdominal pain.

Pedunculated Hepatocellular Carcinoma is an extremely rare neoplasm. There are less than 30 documented cases in the world literature. We present a case which was diagnosed preoperatively using abdominal CT scan and angiography. The fact that the pedunculated tumor had undergone torsion with some necrosis precipitated symptoms of abdominal pain. This is the first reported case of this rare tumor presenting with torsion.

Evaluation of changes in diatom mobility after exposure to 16-Hz electromagnetic fields.

The effect of a 16-Hz electromagnetic field on the mobility of the diatom Amphora coffeaformis was examined on agar plates that contained no added calcium and also on agar plates containing 0.25 or 2.5 mM exogenous Ca2+. Exposure conditions consisted of an ac field of 16 Hz with an amplitude of 20.9 microT parallel to the horizontal component of the dc field (BH = 20.9 microT, where BV = 0). To assess results, the percentage of diatoms that moved a distance greater than their body length was determined. We observed the field-associated increase in diatom motion at 0.25 mM Ca++, which was previously reported in the literature. Although the magnitude of the effect at 16 Hz was significant, the percentage of cells that moved was not sufficiently reproducible to allow examination for frequency dependence.

Contribution of women dentists to dental research.

Since the mid-1960s, the number of women in dentistry in the USA has increased dramatically, including women in dental research. Their attraction to the dental profession is motivated by the following factors: the desire to be a part of the delivery of health care in the community; independence and the opportunity to develop individual expression of career goals; and a career that is compatible with the demands of a family. There is every indication that the proportion of women in dental research will continue to increase in the next decade.

Exposure of mammalian cells to 60-Hz magnetic or electric fields: analysis of DNA repair of induced, single-strand breaks.

DNA damage was induced in isolated human peripheral lymphocytes by exposure at 5 Gy to 60Co radiation. Cells were permitted to repair the DNA damage while exposed to 60-Hz fields or while sham-exposed. Exposed cells were subjected to magnetic (B) or electric (E) fields, alone or in combination, throughout their allotted repair time. Repair was stopped at specific times, and the cells were immediately lysed and then analyzed for the presence of DNA single-strand breaks (SSB) by the alkaline-elution technique. Fifty to 75 percent of the induced SSB were repaired 20 min after exposure, and most of the remaining damage was repaired after 180 min. Cells were exposed to a 60-Hz ac B field of 1 mT; an E field of 1 or 20 V/m; or combined E and B fields of 0.2 V/m and 0.05 mT, 6 V/m and 0.6 mT, or 20 V/m and 1 mT. None of the exposures was observed to affect significantly the repair of DNA SSB.

Quiescent human lymphocytes do not contain DNA strand breaks detectable by alkaline elution.

On the basis of qualitative assays, quiescent lymphocytes have previously been reported to have numerous DNA strand breaks, which are thought to be repaired after mitogenic stimulation by a process associated with poly(ADP-ribosyl)ation. Using alkaline elution, a very sensitive assay for quantifying DNA single-strand breakage, we found no evidence for a high frequency of DNA strand breaks in unstimulated human peripheral blood lymphocytes. No differences in elution profiles were observed between unstimulated lymphocytes and lymphocytes 4 or 48 h after addition of the mitogen phytohemagglutinin (PHA). Furthermore, addition of 3-aminobenzamide (3AB), an inhibitor of poly(ADP-ribose) synthetase, or aphidicolin, an inhibitor of DNA polymerase alpha, did not increase the amount of DNA eluting from the filter after PHA stimulation. In contrast to reported studies of mouse splenic lymphocytes, we found that human lymphocytes were able to replicate and divide in the presence of the ADP-ribosylation inhibitor. Human lymphocytes were also capable of proliferating in nicotinamide-free medium, with or without 3AB, indicating that ADP-ribosylation is not a requirement for lymphocyte differentiation. We therefore consider it unlikely that peripheral human lymphocytes contain significant numbers of strand breaks that play any role in their stimulation or differentiation in response to PHA.

Single strand DNA breaks in human leukocytes induced by ultrasound in vitro.

Single strand breaks (SSBs) in the DNA of fresh human leukocytes were analyzed after in vitro exposure to ultrasound in an ice bath. The alkaline elution method was used to quantify the frequency of SSBs. Five different ultrasonic exposures were employed: (1) 53 mW/cm2 spatial-peak temporal-average intensity (SPTA), 0.37:100 microseconds pulsed 6.2 MHz ultrasound presumably without cavitation, (2) 470 mW/cm2 (SPTA) continuous 1.7 MHz ultrasound with gas-body activation, which is a form of cavitation lacking in chemical activity, (3) 10.8 W/cm2 (SPTA), 3.0:100 microseconds pulsed 1.48 MHz ultrasound, presumably without cavitation, (4) 161 W/cm2 (SPTA) continuous 1.45 MHz ultrasound with transient cavitation, and (5) 94 W/cm2 (SPTA) continuous 8 MHz ultrasound presumably without cavitation. All of these exposures produced negative results, except (4), which yielded a significantly increased frequency of SSBs relative to sham exposed cells. For this condition, the SSB effect was comparable in magnitude to that of 1 Gy of 60Co gamma-rays, and may have resulted from the chemical activity associated with transient cavitation. The SSBs were detected in cells which remained intact after exposure; however, it is uncertain if any of the ultrasonically-induced SSBs occurred in viable cells.

Exposure of mammalian cells to 60-Hz magnetic or electric fields: analysis for DNA single-strand breaks.

Chinese hamster ovary (CHO) cells were exposed for 1 h to 60-Hz magnetic fields (0.1 or 2 mT), electric fields (1 or 38 V/m), or to combined magnetic and electric fields (2 mT and 38 V/m, respectively). Following exposure, the cells were lysed, and the DNA was analyzed for the presence of single-strand breaks (SSB), using the alkaline elution technique. No significant differences in numbers of DNA SSB were detected between exposed and sham-exposed cells. A positive control exposed to X-irradiation sustained SSB with a dose-related frequency. Cells exposed to nitrogen mustard (a known cross-linking agent) and X-irradiation demonstrated that the assay could detect cross-linked DNA under our conditions of electric and magnetic field exposures.

Isolation and culture of adult hepatocytes from liver biopsies.

Hepatocytes were isolated from liver biopsies of rats, guinea pigs, rabbits, dogs, and humans. The procedure is based on cannulation of large veins in the cut face of the biopsy, followed by collagenase perfusion. Yields averaged 19 x 10(6) viable hepatocytes/g liver. Viability averaged 84%, as determined by trypan blue dye exclusion. Cultures were prepared from the isolated hepatocytes and were found to be comparable in morphology and N-demethylase activity to hepatocyte cultures prepared by the in situ perfusion of the liver. The development of this method should facilitate comparative studies of the cytotoxicity, genotoxicity, and metabolism of foreign chemicals in primary hepatocyte cultures.