Reduction in enkephalin and substance P messenger RNA in the striatum of early grade Huntington's disease: a detailed cellular in situ hybridization study

The expression of enkephalin and substance P messenger RNAs was examined in the caudate-putamen of human post mortem tissue from control and Huntington's disease tissue using in situ hybridization techniques and human specific enkephalin and substance P [35S] oligonucleotides. Macroscopic and microscopic quantification of enkephalin and substance P gene expression was carried out using computer-assisted image analysis. Tissue was collected from six control cases with no sign of neurological disease and six Huntington's disease cases ranging from grades 0 to 3 as determined by neuropathological evaluation. The clinical and pathological diagnosis of Huntington's disease was confirmed unequivocally by genetic analysis of the CAG repeat length in both copies of IT15, the Huntington's disease gene. A marked reduction in both enkephalin and substance P messenger RNAs was detected in all regions of the caudate nucleus and putamen in Huntington's disease grades 2/3 when compared to controls; in the dorsal caudate few enkephalin or substance P messenger RNA-positive cells were detected. For the early grade (0/1) Huntington's disease cases, a heterogeneous reduction in both enkephalin and substance P messenger RNAs were noted; for enkephalin messenger RNA the striatal autoradiograms displayed a conspicuous patchy appearance. Detailed cellular analysis of the dorsal caudate revealed a striking reduction in the number of enkephalin and substance P messenger RNA-positive cells detected and in the intensity of hybridization signal/cell. These data suggest that both the "indirect" GABA/enkephalin and "direct" GABA/substance P pathways are perturbed very early in the course of the disease and that these early changes in chemical signalling may possibly underlie the onset of clinical symptoms.     

Intracellular fatty acid-binding proteins: putting lower vertebrates in perspective

Intracellular fatty acid-binding proteins (FABPs) are small (15 kDa), highly conserved cytoplasmic proteins that bind long-chain fatty acids and other hydrophobic ligands. Fifteen isoforms have been identified and characterized to date. Members of the FABP protein family share many common characteristics: they have a common "clamshell" tertiary structure despite significant variation in primary structure; they bind their ligands with 1:1 molar stoichiometry and micromolar affinity (with the exception of liver type FABP, which binds two fatty acids per FABP); they are ubiquitously expressed, yet are found at greatest concentration in tissues with high capacities to oxidize or store lipids; and their level of expression changes with conditions that affect overall lipid metabolism. Because of the ligands bound by FABP and FABP's tissue distribution, it is thought that FABPs play a role in the intracellular metabolism of lipids; however, a precise function(s) for FABP has not been defined. This review highlights contributions from researchers studying FABP in nonmammalian systems. FABPs isolated from birds, fish, amphibians, insects, and flatworms have similar structures to mammals in FABPs, yet they are expressed in systems with unique lipid metabolisms. Because mammals are closely related and have relatively invariant fatty acid metabolisms, non-mammals provide alternative systems that may reveal the elusive function(s) of this protein family.     

Polymerase chain reaction and other amplification techniques in mycobacteriology

Amplification methods for detection of Mycobacterium tuberculosis, such as polymerase chain reaction (PCR), have undergone much research and development in the last several years. The most common methods for extraction, amplification, and detection of mycobacterial nucleic acid sequences used in "in-house" PCR assays are discussed. A list of commercially prepared PCR and non-PCR amplification assays that should be available soon is included. The pros and cons of "in-house" versus commercial technology and issues of implementation of molecular technology in the clinical laboratory are reviewed.     

Nitric oxide production by mouse bone marrow-derived dendritic cells: implications for the regulation of allogeneic T cell responses

Dendritic cells (DC) are the most potent known antigen presenting cells, and play important roles both in immunity and tolerance induction. Nitric oxide (NO) is an important effector molecule that is involved in numerous aspects of the immune response. There have been no accounts to date of efforts to determine NO generation by well-characterized DC. In this report we describe the production of NO by highly purified DEC 205+ DC propagated from mouse bone marrow in response to granulocyte/macrophage-colony stimulating factor (GM-CSF) + interleukin-4 (IL-4). NO synthesis was induced in DC by interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS), and was blocked by the inhibitor of nitric oxide synthase (NOS), NG-monomethyl-L-arginine (NMMA). Both "mature" B7-2+ (CD86+) DC and B7-2- (CD86-) DC progenitors could be induced to release NO. NO was also recovered from the supernatants of primary mixed leukocyte cultures containing comparatively high concentrations of B7-2+ DC in relation to purified allogeneic T cells. Furthermore, inhibition of NO release in these cultures by NMMA resulted in an increase in T cell proliferation. These observations suggest that NO may be an important soluble mediator of the interaction between DC and activated T cells. In addition to its ability to inhibit T cell proliferation, NO was also shown to induce programmed cell death in DC. This was visualized by the detection of DNA strand breaks with in situ nick translation. The percentage of DC apoptosis correlated with the level of NO in the cultures. Apoptosis was inhibited by the addition of NMMA. These results indicate that DC have the capacity both to stimulate and potentially limit the same allogeneic T cell response, in accordance with their production of NO.     

Response properties of neurons in the inferior colliculus of the monaurally deafened ferret to acoustic stimulation of the intact ear

Response properties of neurons in the central nucleus of the inferior colliculus (ICC) were investigated after unilateral cochlear removal at various ages during infancy. Nineteen ferrets had the right cochlea surgically ablated, either in adulthood or on postnatal day (P) 5, 25, or 40, 3-18 mo before recording. Adult ablations were made on the same day as ("acute," n = 3), or 2-3 mo before ("chronic," n = 3), recording. Two ferrets were left binaurally intact. Single-unit (n = 702) and multiunit (n = 1,819) recordings were made in the ICC of barbiturate-anesthetized ferrets ipsilateral (all ages) or contralateral (P5 and acute adult only) to the intact ear. In binaurally intact animals, tonal stimulation of the contralateral ear evoked excitatory activity at the majority (94%) of recording loci, whereas stimulation of the ipsilateral ear evoked activity at only 33% of recording loci. In acutely ablated animals, the majority of contralateral (90%) and ipsilateral (70%) loci were excited by tonal stimulation of the intact ear. In chronically ablated animals, 80-90% of loci were excited by ipsilateral stimulation. Single-unit thresholds were generally higher for low-best frequency (BF) than for high-BF units, and higher in the ipsilateral than in the contralateral ICC. Analysis of covariance showed highly significant differences between all of the ipsilateral and contralateral groups, but no effects of age at ablation or survival time following ablation, other than that the group ablated at P25 had higher mean ipsilateral thresholds than the groups ablated at P5 or, acutely, in adulthood. Cochlear ablation at P5, 25, or 40 resulted in a significant increase in dynamic ranges of ipsilateral ICC unit rate-intensity functions relative to acutely ablated animals. Dynamic ranges of units in the contralateral ICC of P5-ablated ferrets were also significantly increased compared with those of acutely ablated animals. Cochlear ablation at P5, 25, or 40 resulted in a significant increase in single-unit spontaneous discharge rates in the ICC ipsilateral but not contralateral (P5 only) to the intact ear. These data show that unilateral cochlear removal in adult ferrets leads to a rapid and dramatic increase in the proportion of neurons in the ICC ipsilateral to the intact ear that is excited by acoustic stimulation of that ear. In addition, the data confirm that, in ferrets, cochlear removal in infancy leads to a further increase in responsiveness of individual neurons in the ipsilateral ICC. Finally, the data show that responses in the ICC contralateral to the intact ear are largely but not completely unchanged by unilateral cochlear removal.     

The CT halo sign: a new finding in intestinal lymphangiectasia

A "halo sign" has been described in patients with Crohn disease, ulcerative colitis, radiation enteritis, ischemic colitis, and pseudomembranous colitis. This sign is characterized by an inner ring of low CT attenuation surrounded by a higher attenuation outer ring. We present a patient with primary intestinal lymphangiectasia in whom CT demonstrated a halo sign correlated with mucosal biopsy.     

Attitudes, beliefs, and practices regarding smoking and smoking cessation among African-American physicians and dentists

African-American physicians and dentists in metropolitan Atlanta were surveyed to assess smoking cessation practices and perceptions. Questionnaires were mailed to 373 physicians and 90 dentists. A total of 154 questionnaires were returned, for an overall response rate of 33.3%. More physicians than dentists considered smoking a "very serious" threat to patients' health, and physicians were more likely to document smoking status in charts and to counsel smokers to quit. Physicians also were approached more frequently by patients seeking cessation advice. Both types of practitioners considered the nicotine patch, formal cessation programs, and behavior modification/psychotherapy to be among the most effective cessation methods, and nicotine gum and acupuncture to be among the least effective. These results indicate African-American physicians are much more involved than dentists in promoting smoking cessation among patients. Advice of health professionals generally is viewed as a powerful influence for African-American patients. Further work is needed to utilize fully the power of health care providers, especially dentists, in the fight against tobacco-related morbidity and mortality.     

Building laminate veneers and fixed bridges with polymer glass technology

A new type of material is being introduced to American dentistry. The material is a polymer glass, tested in Europe as Artglass. The material is purported to be equal to or better than porcelain for esthetic dentistry. The strength, color translucency, and color vitality allow minimal destruction of enamel for esthetics. An Artglass occlusal is less abrasive to enamel than porcelain and approximates gold. The characteristics of this material system introduces "minimal invasive dentistry" to routine dental repair and reconstruction. A case study of the senior author's reconstruction of his anterior teeth is presented.     

Molecular kinetics and multiline model for the E-beam pumped XeF(B-X) laser

A physical model of the time-, temperature- and wavelength-dependent behavior of an E-beam pumped XeF(B-X) laser is developed. Correlations with published laser- and fluorescence-efficiency data, laser spectra, gain, and absorption data are discussed.     

Effect of antacid on bioavailability of a sustained-release theophylline preparation

The effect of coadministration of an antacid on bioavailability of a sustained-release theophylline tablet preparation (Theo-Dur) was studied by crossover comparison in five young, healthy, nonsmoking volunteers. Water 90 ml, or "high potency" aluminum-magnesium hydroxide antacid (Mylanta II) 10 ml and water 80 ml were administered concurrently with sustained-release theophylline 600 mg. Eleven blood samples were collected over the next 24 hours. Serum was analyzed with high pressure liquid chromatography technique to determine theophylline concentration. Peak serum concentration (Cmax) and time to peak concentration (tmax) were determined, and area under the 24-hour serum concentration-time curve (AUC) was calculated by the trapezoidal rule for each subject at each study interval. The Student's paired t-test was used to compare Cmax, tmax, and AUC for both treatments. A uniform difference was found between groups in Cmax. Cmax was higher in subjects when treated with the antacid (10.45 +/- 3.03 vs. 8.30 +/- 2.90 micrograms/ml, p less than 0.05) than when given theophylline alone. The mean tmax for the two treatments did not differ (10.4 +/- 1.67 h-combination vs. 10.8 +/- 1.1 h-theophylline, p greater than 0.05). Likewise, mean AUC was unchanged by the coadministration of antacid (140.65 +/- 41.6 micrograms/ml.h--combination vs. 155.13 +/- 46.6 micrograms/h--theophylline, p greater than 0.05). The use of a high-potency antacid product did not decrease the extent of theophylline absorption from this sustained-release product, but did increase Cmax and, presumably, rate of absorption. High-potency aluminum-magnesium antacids can probably be used in combination with this sustained-release theophylline tablet without detriment to therapy.