Three genes with different functions in transformation are regulated by c-Myb in myeloid cells

The proto-oncogene c-myb is constitutively expressed in murine leukemia virus-induced myeloid leukemia (MML) due to the integration of virus at this locus. Our recent focus has been the determination of genes regulated by this transcription factor that may be involved in transformation. Data presented here, using conditional expression of Myb in myeloid cells, show that c-Myb directly transactivates the endogenous c-myc and Bcl-2 genes, which explains at least in part how c-Myb regulates proliferation and survival. In addition, c-Myb prevents expression at the RNA level of the tumor suppressor INK4b gene. This gene encodes a cyclin-dependent kinase inhibitor, p15INK4b, that is normally upregulated at the mRNA level during myeloid differentiation and promotes growth arrest. The MMLs are generally characterized as differentiated monocytic tumors and possess the phenotype that is normally associated with p15INK4b expression. c-Myb inhibits expression of this gene, however, and therefore acts to promote a pathway which is abnormal in mature cells. This activity of c-Myb collaborates with its maintenance of c-myc expression to promote growth.

Nerve blocks versus subcutaneous infiltration for stereotactic frame placement

In this unblinded, randomized controlled trial, we compared supraorbital and greater occipital nerve blocks with subcutaneous infiltration for anesthesia during the placement of a stereotactic head-frame. Twenty consecutive patients scheduled for functional surgery to treat Parkinson's disease were studied. Each patient received supraorbital and greater occipital nerve blocks on one side of the head and subcutaneous infiltration on the other, thereby acting as their own control. Pain was assessed by visual analog scale pain scores (scale: 0-100) for both local anesthetic injection and stereotactic pin placement. Supplementary subcutaneous infiltration was also recorded. Results are presented as mean +/- SD. Nerve blocks were significantly less painful than subcutaneous infiltration of local anesthetic at both the frontal (34 +/- 24 vs 49 +/- 25) and occipital (34 +/- 21 vs 49 +/- 23) sites. Neither technique was superior in preventing pain associated with pin placement, at either the frontal site (48 +/- 27 vs 46 +/- 24) or occipital site (33 +/- 27 vs 32 +/- 24). Supraorbital nerve blocks required significantly more supplementation than either greater occipital nerve blocks or subcutaneous infiltration. Visual analog scale pain scores were greater at local anesthetic injection and pin placement than at any subsequent time. We conclude that supraorbital and greater occipital nerve blocks are an alternative to subcutaneous infiltration for the placement of a stereotactic frame.

Co-inheritance of mutations in the uroporphyrinogen decarboxylase and hemochromatosis genes accelerates the onset of porphyria cutanea tarda

Porphyria cutanea tarda is a skin disease caused by photosensitization by porphyrins whose accumulation is caused by deficiency of hepatic uroporphyrin- ogen decarboxylase activity. Mutations in the uroporphyrinogen decarboxylase gene are present in the low-penetrant, autosomal dominant familial form but not in the commoner sporadic form of porphyria cutanea tarda. We have investigated the relationship between age of onset of skin lesions and mutations (C282Y, H63D) in the hemochromatosis gene in familial (19 patients) and sporadic porphyria cutanea tarda (65 patients). Familial porphyria cutanea tarda was identified by mutational analysis of the uroporphyrinogen decarboxylase gene. Five previously described and eight novel mutations (A80S, R144P, L216Q, E218K, L282R, G303S, 402-403delGT, IVS2 + 2 delTAA) were identified. Homozygosity for the C282Y hemochromatosis mutation was associated with an earlier onset of skin lesions in both familial and sporadic porphyria cutanea tarda, the effect being more marked in familial porphyria cutanea tarda where anticipation was demonstrated in family studies. Analysis of the frequencies of hemochromatosis genotypes in each type of porphyria cutanea tarda indicated that C282Y homozygosity is an important susceptibility factor in both types but suggested that heterozygosity for this mutation has much less effect on the development of the disease.

Lecture 5: erectile dysfunction in the HIV-positive male: a review of medical, legal and ethical considerations in the age of oral pharmacotherapy

Urologists and health care professionals treating erectile dysfunction face a significant challenge in caring for the HIV-positive patient who seeks restoration of normal sexual function. The encounter between the health care provider and the patient in this setting requires knowledge of HIV disease and potential drug interactions specific to this population, as well as thorough counseling on strategies aimed at reducing the infectiousness of HIV-1. The interaction extends beyond the immediate boundaries of the doctor-patient relationship and their respective rights, to include careful consideration of the rights of the partner/s and the society as a whole. This paper is a summary and analysis of presentations and discussions by medical, legal, nursing and bioethics specialists in an interactive seminar on this topic.

Assessing cardiovascular functioning in older people

The cardiovascular system comprises the heart and blood vessels. The heart circulates the blood through the vascular system to supply oxygen and nutrients to the peripheral tissues and remove carbon dioxide and other waste products. The blood has other functions such as distributing heat around the body and fighting infection. With the cardiovascular system it is difficult to separate the effects of normal ageing from disease processes (Watson 2000a). However, the process of atherosclerosis is almost universal in older people and is largely responsible for the higher prevalence of cardiovascular problems in older people (Hall et al 1993).

Medications and older people

The key to benefiting older people through medication lies in the proper diagnosis of illness, correct prescription of drugs and vigilant monitoring of intended and unintended drug actions.

Isolation and characterization of the human A-myb promoter: regulation by NF-Y and Sp1

The A-myb transcription factor shows a restricted tissue distribution and is cell cycle regulated. Furthermore its deregulation has profound effects on the growth and/or differentiation of the cells in which it is normally expressed. We have therefore characterized its promoter. A 12 kb genomic clone was isolated that comprises the first exon, part of the first intron as well as upstream regulatory sequences. Multiple transcription start sites have been identified which operate in both B lymphocytes and epithelial cells and the upsteam region was shown to have promoter, activity. The boundaries of the minimal promoter region (-183-14), of a positive upstream (-538-183) and a negative downstream regulatory region (NRE) (+83+374) have been defined. The NRE is promoter- and orientation-independent but position specific. The A-myb minimal promoter is GC-rich, does not contain any TATA box but has a functional CCAAT box. The CCAAT box and minimal promoter is highly conserved in the corresponding murine sequence. The CCAAT box efficiently binds the NF-Y complex and its mutation decreases basal promoter activity by 50%. Two Sp1 binding sites are present upstream from the CCAAT box which can bind Spl and contribute to A-myb promoter activity by 70 and 30%, respectively. The two Sp1 sites and CCAAT box together contribute to over 80% of A-myb basal promoter activity and are therefore the major regulatory elements. Finally, we show that the promoter is cell cycle regulated and that the SP1 and CCAAT elements are required for S phase induction.

Symptom perception during acute bronchoconstriction

The hypothesis underlying the present study was that some of the variability in symptom intensity seen during acute bronchoconstriction may result from varying intensities of several stimuli yielding several sensations that can be identified by specific descriptive expressions (symptoms). A total of 232 subjects inhaled methacholine in doubling concentrations to a 20% decrease in FEV(1), or 64 mg/ml. The study identified the prevalence of dyspnea, nonspecific discomfort associated with the act of breathing, and 10 specific symptom expressions. Each symptom intensity was rated in Borg scale units. The contribution of the specific symptoms to the intensity of dyspnea is illustrated in the following equation (r = 0. 84): Dyspnea = 0.44 + 0.19 Difficult breathing + 0.41 Chest tightness + 0.20 Breathlessness + 0.14 Labored breathing + 0.11 Chest pain. Dyspnea was more intense with broncho-constriction, baseline pulmonary impairment, weight, and sex (being female). Dyspnea was less intense with age (being older) and as airway responsiveness to methacholine increased (p < 0.05 for all factors). Chest tightness and chest pain were at polar extremes on the discrimination scale, i.e., easily discriminated; chest tightness, difficult and labored breathing were not easily discriminated.

Early diagnostic magnetic resonance imaging in acute disseminated encephalomyelitis

We report two cases and review the literature concerning the importance of early magnetic resonance imaging (MRI) of the brain as a guide for the early diagnosis and treatment of acute disseminated encephalomyelitis (ADEM). A nonspecific term, ADEM refers to an acute disease that is postinfectious, parainfectious, postvaccinal, or of an unknown precipitating factor. Often when there is clinical suspicion of ADEM, MRI is not done before significant morbidity and mortality occur, despite the existence of adequate treatments. Primary care physicians should be aware of the importance of early MRI in ADEM.