RNA Synthesis in Cultures of Normal Human Peripheral Blood

RNA and DNA synthesis were measured in cultures of normal human peripheral blood using tritiated cytidine and thymidine and autoradiographictechnics. RNA synthesis preceded DNA synthesis by 24 hours. RNA synthesisoccurred predominantly in the large and medium-sized "blast-like" cells, butdid occur, to a lesser extent, in the small lymphocytes. RNA synthesis did notoccur in the absence of phytohemagglutinin, nor did DNA synthesis. Mechanisms of action of phytohemagglutinin are discussed with particular referenceto its possible antigenic nature.

Submitted on August 12, 1963 Accepted on January 6, 1964     

Solid phase red cell adherence immunoassay for anti-HIV 1: a simple, rapid, and accurate method for donor screening

In technically developed countries in which acquired immunodeficiency syndrome is a risk to the recipients of blood or tissue, it is mandatory to screen the donor for evidence of HIV (human immunodeficiency virus) infection. Current tests, based on enzyme-linked immunoassay, are time-consuming and expensive and as such are unsuitable for developing countries. We describe a second generation test using anti-human IgG coupled to red cells as the indicator of antibody having reacted with test antigen (1). The test is complete within ten minutes, simple to perform and to read and has 100% sensitivity and 99% specificity compared with Western blot. It is ideal for the rapid screening of organ donors and for the screening of blood donors where cost is a major consideration.     

Review article: urease, gastric ammonium/ammonia, and Helicobacter pylori — the past, the present, and recommendations for future research

The presence of ammonium in gastric contents was described in 1852; urease activity in the stomach was identified 70 years later. The discovery of gastric urease resulted in intense research activity to discover its origin, function, and relation to the gastric levels of ammonium and urea. Interest in urease waned in the 1960s as most pertinent questions appeared to have been addressed and there was strong evidence that gastric urease was not a property of the stomach but was of microbial origin. Identification of Helicobacter pylori as the source of urease in the stomach in the last decade has resulted in a rebirth of interest in gastric urease and its products.^1–15 There is little actual evidence to support a role for toxicity of ammonia in relation to H. pylori and the bulk of the evidence suggests that the products of urease activity are not toxic and may even be beneficial. The purpose of this review is to examine the older literature and to examine- new findings in the perspective of what is already known and to suggest areas remaining to be examined. We ask, ‘What is old, what is new, and what needs to be done?’     

Metabolism and RNA incorporation of cyclopentenyl cytosine in human colorectal cancer cells.

We studied the cytotoxicity and metabolism of the investigational cytidine analogue cyclopentenyl cytosine (CPE-C) in three human colorectal cancer cell lines: HCT 116, SNU-C4, and NCI-H630. CPE-C potently inhibited cell growth and decreased clonogenic capacity at concentrations achieved in murine and primate pharmacologic studies. CPE-C produced a concentration-dependent depletion of CTP, accompanied by changes in the dCTP pools. CPE-C exposure was associated with an accumulation of cells in the S phase at 48 hr. [3H]CPE-C was metabolized predominantly to the triphosphate (CPE-CTP) form. Saturation of phosphorylation to the monophosphate form occurred above 5-10 microM. Plateau CPE-CTP pools were of a magnitude similar to that of the physiologic ribonucleotide triphosphate pools. The intracellular half-life of CPE-CTP was 24 hr. After a 24-hr exposure to 0.5 microM CPE-C, CPE-CTP was detected for up to 96 hr post-drug removal, accompanied by persistent depletion of the CTP pools. Cesium sulfate density centrifugation of purified nucleic acids indicated that [3H]CPE-C incorporated into RNA, but was not detected in DNA. Agarose-gel electrophoresis of RNA from [3H]CPE-C-treated cells indicated that it localized predominantly in low molecular weight (4-8 S) RNA species. When CPE-C was administered concurrently with [3H]adenosine (Ado), the proportion of [3H]Ado migrating with low molecular weight RNA species increased. Concurrent exposure to 10 microM cytidine (Cyd), sufficient to replete CTP pools, provided essentially complete protection against lethality resulting from a 24-hr exposure to less than or equal to 0.5 microM CPE-C. While 10 microM Cyd substantially decreased CPE-CTP formation and CPE-C-RNA incorporation during the initial 3 hr of exposure compared to CPE-C alone, after 24 hr the levels were not significantly different. Cyd rescue did not affect the accumulation of [3H]CPE-C or [3H]Ado into low molecular weight RNA species after a 24-hr exposure to CPE-C. Our results indicate that depletion of CTP and dCTP pools is an important component of CPE-C cytotoxicity. While CPE-C incorporation into RNA may not be the critical cytotoxic event during a 24-hr exposure to CPE-C, it may play a role during prolonged exposure to CPE-C. CPE-C is a highly potent new agent and merits clinical evaluation in the treatment of colorectal cancer.     

Characteristics of Mohs Practices in the United States: A Recall Survey of ACMS Surgeons

OBJECTIVE The purpose of this study is to better characterize the typical Mohs practice in the United States and to generate data that may be useful in future practice models.
METHODS A survey was mailed in 2004 to all 599 members of the American College of Mohs Surgery with United States addresses listed in the 2003 directory.
RESULTS Most respondents were part of a single speciality group, in a suburban or urban setting, performed between 501–1,000 cases per year, and had been in practice from 0–5 years. The vast majority of Mohs excisions are for basal cell cancers and squamous cell cancers, followed by melanoma. Primary closure is the most common method of repair, followed by the use of flaps. Only 6% of cases were referred to other specialties for closure. Many surgeons augment their practice with non-Mohs cosmetic procedures.
CONCLUSION The characteristics of current Mohs surgery practices in the United States provides useful data for training programs, potential trainees, workforce issues, statistical modeling systems, and Mohs surgeons in the evaluation of their own practices.     

Chronic paroxysmal hemicrania. VII. Mechanical precipitation of attacks: new cases and localization of trigger points

Two new chronic paroxysmal hemicrania patients are described. In both, attacks can be precipitated mechanically by applying firm manual pressure to certain sensitive points on the neck, i.e. in the C2 area, in the transverse processes of the C4–C5 vertebrae, or beneath the posterior part o15 the skull on the symptomatic side. The most sensitive area seems to be the transverse process of C4–C5. Susceptibility to this type of attack is dependent on the flow of spontaneous attacks; attacks are easily precipitated in a phase with multiple spontaneous attacks, but are not readily precipitated otherwise. Under indomethacin protection, local tenderness is clearly diminished and attacks cannot be precipitated.     

One year's experience in a new dental day-stay unit

The records of six hundred and fifty-five patients treated in the Dental Day-Stay Unit over a twelve-month period were reviewed. 2.1% of 95 patients assessed as suitable for day-stay surgery, and 2.2% of 542 patients not assessed prior to anaesthesia were admitted postoperatively. As an index of outcome, 2.56% of 547 day cases were admitted postoperatively, 0.73% being attributable to anaesthesia. Forty-seven day patients were treated in the dental chair, and 108 were treated as inpatients. Over 37% had at least one concurrent medical problem, while 10.4% were mentally handicapped. Guidelines for day-care selection require that the procedure be straightforward, the patient medically fit, be discharged escorted, and live within a reasonable distance of the hospital. From our study, four specific patient groups are identified. These are: the young and healthy, the mentally handicapped, the medically compromised, and those with airway problems.     

Multisection-multiecho MR imaging: effect on image quality

An analysis of the effects of multisection-multiecho imaging on signal intensity is presented using a gaussian excitation pulse. The number of sections acquired, size of the intersection gap, and the number of echoes were all varied independently to evaluate their effect on image intensity. The results indicate that one should take a conservative approach in multisection-multiecho imaging, leaving at least a 2-mm-intersection gap and approximately a 20-msec delay between section excitations to avoid image signal loss owing to partial saturation effects.