Retinoic acid receptors in myeloid leukemia: characterization of receptors in retinoic acid-resistant K-562 cells.

Although mRNA for the retinoic acid receptor alpha (RAR-alpha) is expressed in many different myeloid leukemias, most of these leukemia cells exhibit little if any phenotypic response when exposed to retinoic acid (RA). To determine whether such RA resistance is related to altered RA receptor structure or function, we performed a detailed analysis of nuclear RA receptors in RA-resistant K-562 cells. These cells exhibit RA receptors of the same approximate molecular weight and similar kd as those exhibited by the RA-sensitive HL-60 leukemia cell line, but the number of RA receptors in the RA-resistant K-562 cells (80 per cell) is significantly lower than that exhibited by RA-sensitive HL-60 cells (550 per cell). Retroviral-mediated transduction of RAR-alpha cDNA into K-562 significantly increased the number of RA receptors to 2,000 per cell. These RAR-alpha-transduced K-562 cells, when incubated with RA, exhibit diminished cell proliferation associated with decreased c-myc expression and an accumulation of cells in G0/G1. In addition, these RA-treated cells exhibit downregulation of the CD15 surface antigen and a slight increase in hemoglobin production but manifest no other evidence of significant erythroid, megakaryocytic, or myeloid differentiation. These results indicate that an elevated number of nuclear RA receptors can be involved in altering proliferation but not necessarily the differentiation of certain RA-treated myeloid leukemia cells.     

Nasal polyposis: prevalence of positive food and inhalant skin tests.

OBJECTIVES: To investigate the etiology of nasal polyps and its relationship to allergy. The prevalence of positive food and inhalant skin tests in patients with nasal polyps and nonatopic controls was compared. STUDY DESIGN AND SETTING: Prospective controlled study in tertiary referral rhinology clinic. RESULTS: Seventy percent (70%) of the patients with nasal polyps had positive skin tests to an average of four foodstuffs, compared to 34 percent of controls (P = 0.006). Only 35 percent of the nasal polyp patients also had positive inhalant skin tests. Overall, the prevalence of positive inhalant skin tests was similar in the nasal polyp patients and controls. CONCLUSIONS: These findings suggest that the positive skin tests to foods are not merely a reflection of the general atopic status of patients with nasal polyps. It may be that non-IgE-mediated hypersensitivities, such as to ingested foods, play a role on the basis of a significant number of patients with positive intradermal skin tests to foods. SIGNIFICANCE: Evaluation of the allergic status of patients with polyposis is important. Dietary manipulation may be indicated, though its role needs further investigation.     

Moment-to-moment dynamics of ADHD behaviour in South African children

Background  

The behaviour of children with Attention-Deficit/Hyperactivity Disorder is characterized by low predictability of responding. Low behavioural predictability is one way of operationalizing intra-individual ADHD-related variability. ADHD-related variability may be caused by inefficient behavioural selection mechanisms linked to reinforcement and extinction, as suggested by the recently published dynamic developmental theory (DDT) of ADHD. DDT argues that ADHD is a basic neurobehavioural disorder, caused by dysfunctioning dopamine systems. For establishing ADHD as a neurobehavioural disorder, findings from studies conducted in Western countries should be replicated in other cultural populations. The present study replicated the study conducted in Norway, with children from the Limpopo province in the Republic of South Africa.     

Assessment of clinical renal preservation by phosphorus-31 magnetic resonance spectroscopy

To evaluate the role of magnetic resonance spectroscopy (MRS) and to develop surface coils for assessing cadaveric renal viability during hypothermic storage, we used the monophosphate/inorganic phosphate ratio (MP/Pi) to monitor phosphorous metabolites in intact kidneys during various renal preservation maneuvers. Eighteen canine kidneys and 16 cadaveric kidneys were studied as follows: Group 1 (N = 4) in situ kidneys were monitored by implanted MRS coils; Group 1 (N = 4) ex vivo kidneys were immediately attached to vascular cannulas and monitored by MRS surface coils during normothermic perfusion; Group 3 (N = 4) kidneys were removed, cold-flushed and, after 24 hours of 4C storage, monitored by MRS surface coils before and during four hours of reperfusion via vascular cannulas; Group 4 (N = 6) kidneys were removed, cold-flushed and monitored by surface coils during cold storage up to 72 hours. In addition, 16 cadaveric kidneys were studied while in sterile cold-storage containers. Postoperative renal function was followed in recipient patients. The MP/Pi ratios in Group 1 kidneys correlated with the ability to regenerate adenosine triphosphate (ATP). Groups 2 and 3 showed similar regeneration of ATP and MP/Pi after postischemic reperfusion, and the signal-to-noise ratios of the surface coils were better than those in the implanted coils in Group 1. Surface-coil monitoring in Group 4 kidneys showed predictable decay rates of MP/Pi during one to 72 hours of cold storage; in contrast, simultaneous cortical medullary microcirculation studies with 99mTc-macroaggregated albumin were inconclusive. Human cadaveric kidneys with high MP levels were associated with excellent renal function after transplantation, while those with low MP (less than or equal to 0.50) were associated with nonviability. We conclude that MRS is a practical and safe diagnostic modality for clinical transplantation.     

Caring for patients with traumatic injuries of the thoracic aorta.

Trauma is a major cause of mortality and morbidity in the United States, with blunt traumatic injuries of the thoracic aorta continuing to occur despite the increased use of seatbelts and airbags. Emerging from crash analysis are effective interventions and provides increased awareness of the occult nature of these types of injuries. This article describes those interventions that healthcare providers must embed throughout the continuum of care for patients experiencing thoracic aortic injuries. Outcomes will be dependent upon the healthcare provider's knowledge of the physics of the event and the urgency of the diagnosis, as well as the ability to assess and manage all the variables involved. Current procedural issues are delineated and case studies are used to illustrate the processes of care needed by these patients.