Review of Ge detectors for gamma spectroscopy

A review is given of the use of germanium detectors for gamma spectroscopy. The advantages, principles of operation, and fabrication processes of semiconductor radiation detectors are described.

Potent inhibition of NFAT activation and T cell cytokine production by novel low molecular weight pyrazole compounds

NFAT (nuclear factor of activated T cell) proteins are expressed in most immune system cells and regulate the transcription of cytokine genes critical for the immune response. The activity of NFAT proteins is tightly regulated by the Ca(2+)/calmodulin-dependent protein phosphatase 2B/calcineurin (CaN). Dephosphorylation of NFAT by CaN is required for NFAT nuclear localization. Current immunosuppressive drugs such as cyclosporin A and FK506 block CaN activity thus inhibiting nuclear translocation of NFAT and consequent cytokine gene transcription. The inhibition of CaN in cells outside of the immune system may contribute to the toxicities associated with cyclosporin A therapy. In a search for safer immunosuppressive drugs, we identified a series of 3,5-bistrifluoromethyl pyrazole (BTP) derivatives that block Th1 and Th2 cytokine gene transcription. The BTP compounds block the activation-dependent nuclear localization of NFAT as determined by electrophoretic mobility shift assays. Confocal microscopy of cells expressing fluorescent-tagged NFAT confirmed that the BTP compounds block calcium-induced movement of NFAT from the cytosol to the nucleus. Inhibition of NFAT was selective because the BTP compounds did not affect the activation of NF-kappaB and AP-1 transcription factors. Treatment of intact T cells with the BTP compounds prior to calcium ionophore-induced activation of CaN caused NFAT to remain in a highly phosphorylated state. However, the BTP compounds did not directly inhibit the dephosphorylation of NFAT by CaN in vitro, nor did the drugs block the dephosphorylation of other CaN substrates including the type II regulatory subunit of protein kinase A and the transcription factor Elk-1. The data suggest that the BTP compounds cause NFAT to be maintained in the cytosol in a phosphorylated state and block the nuclear import of NFAT and, hence, NFAT-dependent cytokine gene transcription by a mechanism other than direct inhibition of CaN phosphatase activity. The novel inhibitors described herein will be useful in better defining the cellular regulation of NFAT activation and may lead to identification of new therapeutic targets for the treatment of autoimmune disease and transplant rejection.

The DNA sequence and comparative analysis of human chromosome 20

The finished sequence of human chromosome 20 comprises 59,187,298 base pairs (bp) and represents 99.4% of the euchromatic DNA. A single contig of 26 megabases (Mb) spans the entire short arm, and five contigs separated by gaps totalling 320 kb span the long arm of this metacentric chromosome. An additional 234,339 bp of sequence has been determined within the pericentromeric region of the long arm. We annotated 727 genes and 168 pseudogenes in the sequence. About 64% of these genes have a 5' and a 3' untranslated region and a complete open reading frame. Comparative analysis of the sequence of chromosome 20 to whole-genome shotgun-sequence data of two other vertebrates, the mouse Mus musculus and the puffer fish Tetraodon nigroviridis, provides an independent measure of the efficiency of gene annotation, and indicates that this analysis may account for more than 95% of all coding exons and almost all genes.

Isolation of an antimicrobial compound from Impatiens balsamina L. using bioassay-guided fractionation

By using brine shrimp (Artemia salina) lethality test-guided fractionation, a single bioactive compound (LC(50)=26 ppm) was isolated from the 95% ethanol extract of the dried aerial parts of Impatiens balsamina L. and subsequently identified as 2-methoxy-1,4-naphthoquinone (MNQ). The structure of MNQ was confirmed by UV, FT-IR, MS, and 1-and 2-D NMR spectroscopy. The antimicrobial activity of MNQ was evaluated using 12 bacterial and eight fungal strains. Five gram-positive and two gram-negative bacteria as well as all eight fungi (including multi-drug resistant strains) tested were highly sensitive to MNQ. A tea prepared according to traditional methods was found to contain sufficient MNQ to account for its antimicrobial properties.

Gender differences in cardiovascular regulation during recovery from exercise

Are women more susceptible to acute postexercise orthostatic hypotension compared with men? We hypothesized that decreases in arterial pressure during recovery from dynamic exercise are greater in women compared with men. We studied 8 men and 11 women during inactive and active recovery from cycling exercise. Heart rate, stroke volume (SV), cardiac output, mean arterial pressure (MAP), and total peripheral resistance (TPR) were measured during and after 3 min of exercise at 60% of calculated maximum heart rate. At 1 min after exercise, MAP decreased less (P < 0.05) during inactive recovery in men (-18 +/- 2 mmHg) compared with women (-30 +/- 2 mmHg). This difference was due to greater decreases in SV and less increase in TPR during inactive recovery from exercise in women compared with men. These differences persisted for 5 min after exercise. MAP decreased less during active recovery in men compared with women. These findings suggest that women may have increased risk of postexercise orthostatic hypotension and that active recovery from exercise may reduce this risk.

Urinary excretion profiles for total morphine, free morphine, and 6-acetylmorphine following smoked and intravenous heroin

Heroin is one of the major target drugs in workplace drug-testing programs because of its history of abuse, liability, and continued negative social impact. This study was a comprehensive examination of pharmacokinetics, pharmacodynamics, detection times, opiate immunoassay performance, and urine excretion profiles following single doses of heroin administered to human subjects via smoking and intravenous routes. Studies of the first four components of this investigation were previously published. This article describes the urine excretion profiles. Total morphine (Tmor), free morphine (Fmor), and 6-acetylmorphine (6-AM) were measured by gas chromatography-mass spectrometry (GC-MS) in 920 urine samples collected from 11 male human subjects following single doses of heroin. Eight received intravenous doses of 3, 6, and 12 mg heroin HCI and four smoked 3.5-, 5.2-, 7-, 10.5-, or 13.9-mg doses of heroin (base). In addition, 183 urine-based blind quality-control samples were added to the study set to assess assay performance. Creatinine was also measured in each sample by a colorimetric technique. The parameters studied were not significantly dependent on route of administration. Excretion half-life mean +/- SD for Tmor was 3.11 +/- 0.30 h. Range (median) of peak urine concentrations, time to peak, time to last positive sample for low cutoff (300 ng/mL) and high cutoff (2000 ng/mL) for Tmor following lower doses (< or = 7 mg) were, respectively, 1392-9250 (3620) ng/mL, 1.2-6.2 (2.3) h, 7.4-31.9 (7.4) h, and 0-10.1 (4.3) h. Following higher doses (> 10 mg) they were 2065-29,030 (16,470) ng/mL, 2.3-9.3 (4.5) h, 10.7-53.5 (34.4) h, 2.3-22.3 (8.3) h. Fmor peaked in the same sample as Tmor. Range (median) of peak Fmor concentrations and time to last positive using a cutoff of 100 ng/mL for low and high doses were, respectively, 117-1160 (415) ng/mL, 1.2-10.1 (4.5) h and 150-2580 (1400) ng/mL, 2.3-29.1 (9.3) h. The range (median) of peak urine concentrations for 6-AM was 6.1-568 (124) ng/mL. In general, the first urine void had the peak 6-AM concentration and was the only specimen positive at a 10-ng/mL cutoff. As previously reported urine concentrations varied greatly between subjects and within subjects with time after dosing but were much more predictable when values were reported as amount of drug per unit of creatinine. The range (median) values for percent of heroin excreted into urine as Tmor was 12.8-88.5% (51.0).

Caterpillar talk: acoustically mediated territoriality in larval Lepidoptera

We provide evidence for conspecific acoustic communication in caterpillars. Larvae of the common hook-tip moth, Drepana arcuata (Drepanoidea), defend silk nest sites from conspecifics by using ritualized acoustic displays. Sounds are produced by drumming the mandibles and scraping the mandibles and specialized anal "oars" against the leaf surface. Staged interactions between a resident and intruder resulted in escalated acoustic "duels" that were typically resolved within minutes, but sometimes extended for several hours. Resident caterpillars generally won territorial disputes, regardless of whether they had built the nest, but relatively large intruders occasionally displaced residents from their nests. All evidence is consistent with acoustic signaling serving a territorial function. As with many vertebrates, ritualized signaling appears to allow contestants to resolve contests without physical harm. Comparative evidence indicates that larval acoustic signaling may be widespread throughout the Lepidoptera, meriting consideration as a principal mode of communication for this important group of insects.

Malignant rolandic-sylvian epilepsy in children: diagnosis, treatment, and outcomes

OBJECTIVE

To describe the diagnosis, treatment, and outcomes in children with malignant rolandic-sylvian epilepsy (MRSE), defined as a form of epilepsy characterized by sensorimotor seizures, medical refractoriness, normal MRI, frontocentrotemporal EEG spikes, rolandic-sylvian spike sources on magnetoencephalography (MEG), and cognitive problems.

METHODS

A retrospective chart analysis of seven patients who had shown these characteristics and undergone extensive diagnostic testing, including MEG and intracranial video-EEG was performed.

RESULTS

Interictal scalp EEG spikes were seen over the frontocentrotemporal regions bilaterally (6) and unilaterally (1). MEG showed spike sources in the perisylvian region in two patients (both bilateral) and in the perirolandic fissure in five (two bilateral). Three patients required bilateral subdural strips to lateralize seizures before electrocorticography. Final electrocorticograms showed an ictal onset zone around the rolandic (four cases) and rolandic-sylvian regions (three cases). Six patients showed neuropsychological deficits. After cortical excision and multiple subpial transection, three were seizure free and four had seizures rarely (30 months' mean follow-up). No child had a permanent deficit in sensorimotor or cognitive functions, although two showed exacerbation of preexisting attentional deficits. Tissue analysis showed definite evidence of neuronal migration disorders (3) and gliosis (2).

CONCLUSIONS

MEG was helpful for localizing both malignant rolandic-sylvian neuronal activities and functional cortex. Successive neuropsychological assessments are necessary to detect cognitive deterioration and indicate remedial programming. If, after careful observation over at least 5 years, surgery is considered to control refractory seizures, intracranial video-EEG is needed to localize the epileptogenic zone.

Characterization of AFLP markers in damselflies: prevalence of codominant markers and implications for population genetic applications

Amplified fragment length polymorphism (AFLP) analysis is becoming increasingly popular as a method for generating molecular markers for population genetic applications. For practical considerations, it is generally assumed in population studies that AFLPs segregate as dominant markers, i.e., that present and absent are the only possible states of a given locus. We tested the assumption of dominance in natural populations of the damselfly Nehalennia irene (Hagen) (Odonata: Coenagrionidae). Electro-blotted AFLP products from 21 samples were probed with individual markers. Eleven markers were analyzed, of which two were monomorphic and nine were polymorphic. Only two of the polymorphic markers behaved in a strictly dominant manner. The remaining seven polymorphic markers displayed various degrees of codominance, with 2-10 visible alleles in the sample. Of the three markers displaying the highest degree of variability, two contained microsatellite repeat tracts. Our results suggest that the assumption of dominance is unfounded. As a result, AFLP analysis may be unsuitable for estimating several important population genetic parameters, including genetic diversity.

Characterization of AFLP markers in damselflies: prevalence of codominant markers and implications for population genetic applications

Amplified fragment length polymorphism (AFLP) analysis is becoming increasingly popular as a method for generating molecular markers for population genetic applications. For practical considerations, it is generally assumed in population studies that AFLPs segregate as dominant markers, i.e., that present and absent are the only possible states of a given locus. We tested the assumption of dominance in natural populations of the damselfly Nehalennia irene (Hagen) (Odonata: Coenagrionidae). Electro-blotted AFLP products from 21 samples were probed with individual markers. Eleven markers were analyzed, of which two were monomorphic and nine were polymorphic. Only two of the polymorphic markers behaved in a strictly dominant manner. The remaining seven polymorphic markers displayed various degrees of codominance, with 2-10 visible alleles in the sample. Of the three markers displaying the highest degree of variability, two contained microsatellite repeat tracts. Our results suggest that the assumption of dominance is unfounded. As a result, AFLP analysis may be unsuitable for estimating several important population genetic parameters, including genetic diversity.

The effect of methyl methanesulfonate (MMS)-induced excision repair on p53-dependent apoptosis in human lymphoid cells

The tumor suppressor p53 product has been shown to play an important role in preventing carcinogenesis by at least two different mechanisms, by evoking cell cycle arrest and eliciting DNA repair on one hand, or by eliminating damaged cells by induction of apoptosis on the other hand. As a first step toward understanding the relationship between protective responses and apoptosis after genotoxic stress, we examined the effect of DNA strand breaks generated from repair processes in respect to acute cellular responses against DNA damage, and on p53-dependent apoptosis in human lymphoid cells. We used two isogenic cell lines, TK6 harboring wild-type p53, and WI-L2-NS, which carries a mutant p53. A significant difference in sensitivity was observed at 50 microg/ml methyl methane-sulfonate (MMS) between the two cell lines used. In addition, a clear p53-mediated contribution to apoptosis in MMS-induced cell death was observed. However, we did not observe any differences in repair of MMS-lesions, as determined by comet assay, between the two cell lines. These data suggest that the differences in apoptosis induction in the two lines are not a reflection of differences in strand-break frequency or repair capacity.

A CD2-green fluorescence protein-transgenic mouse reveals very late antigen-4-dependent CD8+ lymphocyte rolling in inflamed venules

Intravital microscopy allows detailed analysis of leukocyte trafficking in vivo, but fails to identify the nature of leukocytes investigated. Here, we describe the development of a CD2-enhanced green fluorescence protein (EGFP)-transgenic mouse to characterize lymphocyte trafficking during inflammation in vivo. A CD2-EGFP plasmid construct including the CD2 promoter, the EGFP transgene, and the CD2 locus control region was injected into B6CBA/F1 pronuclei. EGFP+ offspring were backcrossed into C57BL/6 mice for six generations. Flow cytometry demonstrated that all peripheral blood EGFP+ cells were positive for CD2 and negative for the granulocyte Ag Ly 6-G (GR-1). EGFP(high) cells stained positive for CD2, CD3, CD8, TCR beta-chain, and NK1.1 but did not express the B cell and monocyte markers CD45RA, CD19, and CD11b. In vitro stimulation assays revealed no difference in lymphocyte proliferation and IL-2 secretion between EGFP+ and EGFP- mice. Intravital microscopy of untreated or TNF-alpha-treated cremaster muscle venules showed EGFP+ cells in vivo, but these cells did not roll or adhere to the vessel wall. In cremaster muscle venules treated with both TNF-alpha and IFN-gamma, EGFP(high) cells rolled, adhered, and transmigrated at a rolling velocity slightly higher (11 microm/s) than that of neutrophils (10 microm/s). Blocking alpha4 integrin with a mAb increased rolling velocity to 24 microm/s. These findings show that CD8+ T cells roll in TNF-alpha/IFN-gamma-pretreated vessels in vivo via an alpha4 integrin-dependent pathway.

Cognitive and motor development in children with vertically transmitted HIV infection

This study was designed to examine mental and motor development in infants with vertically transmitted human immunodeficiency virus (HIV) infection. Early neurodevelopment was examined in 25 young children with HIV infection acquired through vertical transmission. Compared with 25 children born to HIV-positive mothers but not infected with the virus, and after controlling for developmental risk factors, the HIV-infected group showed impairments in mental and motor development. Mental and motor development were assessed using the Bayley Scales of Infant Development. On the mental scale (MDI), the HIV-infected infants obtained significantly lower scores than the uninfected infants. On the performace scale (PDI), the HIV-infected infants obtained significantly lower standard scores than the uninfected infants. CT scan results were available for 20 of the HIV-infected children. CT abnormalities were associated with developmental delays, particularly for motor development. The results point to the importance of early abnormalities in myelination and of subcortical lesions of cognitive and motor development.

Arterial baroreflex control of sympathetic nerve activity during acute hypotension: effect of fitness

We examined arterial baroreflex control of muscle sympathetic nerve activity (MSNA) during abrupt decreases in mean arterial pressure (MAP) and evaluated whether endurance training alters baroreflex function. Acute hypotension was induced nonpharmacologically in 14 healthy subjects, of which 7 were of high fitness (HF) and 7 were of average fitness (AF), by releasing a unilateral arterial thigh cuff after 9 min of resting ischemia under two conditions: control, which used aortic and carotid baroreflex (ABR and CBR, respectively) deactivation; and suction, which used ABR deactivation alone. The application of neck suction to counteract changes in carotid sinus transmural pressure during cuff release significantly attenuated the MSNA response (which increased 134 ± 32 U/14 s) compared with control (which increased 195 ± 43 U/14 s) and caused a greater decrease in MAP (19 ± 2 vs. 15 ± 2 mmHg; P < 0.05). Furthermore, during both trials, the HF subjects exhibited a greater decrease in MAP compared with AF subjects despite an augmented baroreflex control of MSNA. These data indicate that the CBR contributes importantly to the MSNA response during acute systemic hypotension. Additionally, we suggest that an impaired control of vascular reactivity hinders blood pressure regulation in HF subjects.

Hox genes and the phylogeny of the arthropods

The arthropods are the most speciose, and among the most morphologically diverse, of the animal phyla. Their evolution has been the subject of intense research for well over a century, yet the relationships among the four extant arthropod subphyla - chelicerates, crustaceans, hexapods, and myriapods - are still not fully resolved. Morphological taxonomies have often placed hexapods and myriapods together (the Atelocerata) [1, 2], but recent molecular studies have generally supported a hexapod/crustacean clade [2-9]. A cluster of regulatory genes, the Hox genes, control segment identity in arthropods, and comparisons of the sequences and functions of Hox genes can reveal evolutionary relationships [10]. We used Hox gene sequences from a range of arthropod taxa, including new data from a basal hexapod and a myriapod, to estimate a phylogeny of the arthropods. Our data support the hypothesis that insects and crustaceans form a single clade within the arthropods to the exclusion of myriapods. They also suggest that myriapods are more closely allied to the chelicerates than to this insect/crustacean clade.

Necrotic arachnidism

Necrotic arachnidism is the potential cutaneous reaction to spider bite venom. In the United States, members of 7 spider families may be responsible for envenomation sufficiently severe to warrant treatment. Characteristics of several spiders, in particular Loxosceles spiders, whose bite is toxic to humans are described, and diagnostic standards, preventive measures, and treatment options are reviewed. (J Am Acad Dermatol 2001;44:561-73.)

LEARNING OBJECTIVE

After the completion of this learning activity, participants should be familiar with the characteristics of several different spider families endemic to the United States. Furthermore, this learning activity should aid in the prevention and diagnosis of spider bites as well as in the classification and treatment of specific bites.

Carotid baroreflex regulation of sympathetic nerve activity during dynamic exercise in humans

We sought to determine whether carotid baroreflex (CBR) control of muscle sympathetic nerve activity (MSNA) was altered during dynamic exercise. In five men and three women, 23.8 +/- 0.7 (SE) yr of age, CBR function was evaluated at rest and during 20 min of arm cycling at 50% peak O(2) uptake using 5-s periods of neck pressure and neck suction. From rest to steady-state arm cycling, mean arterial pressure (MAP) was significantly increased from 90.0 +/- 2.7 to 118.7 +/- 3.6 mmHg and MSNA burst frequency (microneurography at the peroneal nerve) was elevated by 51 +/- 14% (P < 0.01). However, despite the marked increases in MAP and MSNA during exercise, CBR-Delta%MSNA responses elicited by the application of various levels of neck pressure and neck suction ranging from +45 to -80 Torr were not significantly different from those at rest. Furthermore, estimated baroreflex sensitivity for the control of MSNA at rest was the same as during exercise (P = 0.74) across the range of neck chamber pressures. Thus CBR control of sympathetic nerve activity appears to be preserved during moderate-intensity dynamic exercise.

Effect of P-wave timing during supraventricular tachycardia on the hemodynamic and sympathetic neural response

BACKGROUND

Previous studies have shown the importance of the timing of atrial and ventricular systole on the hemodynamic response during supraventricular tachycardia (SVT). However, the reflex changes in autonomic tone during SVT remain poorly understood.

METHODS AND RESULTS

Eleven patients with permanent dual-chamber pacemakers were enrolled in the study. Arterial blood pressure (BP), central venous pressure (CVP), and peripheral muscle sympathetic nerve activity (SNA) were recorded during DDD pacing at a rate of 175 bpm (cycle length 343 ms) with an atrioventricular (AV) interval of 30, 200 and 110 ms, simulating tachycardia with near-simultaneous atrial and ventricular systole, short-RP tachycardia (RP<PR), and long-RP tachycardia (RP>PR). Each pacing run was performed for 3 minutes separated by a 5-minute recovery period. All patients demonstrated an abrupt fall in BP, an increase in CVP, and an increase in SNA regardless of the AV interval. The decreases in SBP, DBP, and MAP and the increase in CVP were significantly less during long-RP tachycardia (AV interval 110 ms) than during the other 2 pacing modes (P:<0.05), and the increase in SNA in 7 of the 11 patients was significantly greater during closely coupled atrial and ventricular systole than during long-RP tachycardia (P:<0.05).

CONCLUSIONS

These data suggest that the superior maintenance of hemodynamic stability during long-RP tachycardia is accompanied by reduced sympathoexcitation, which is primarily mediated by the arterial baroreceptors, with a modest cardiopulmonary vasodepressor effect.

Antifungal activity of extracts from medicinal plants used by First Nations Peoples of eastern Canada

From literature describing medicinal usage of plants by First Nations Peoples in eastern Canada, 18 eastern Canadian plants were selected and tested for their antifungal activities. Eight randomly selected tropical plants were also tested for comparative purposes. Four groups of plants were obtained: popular antimicrobial-remedy (n=6), popular non-antimicrobial-remedy (n=6), random temperate (n=6) and random tropical (n=8). Extracts from these plants were tested in disk assays as growth inhibitors of six fungi known to be opportunistic human pathogens (Saccharomyces cerevisiae, Cryptococcus neoformans, Candida albicans, Aspergillus fumigatus, Microsporum gypseum and Trichophyton mentagrophytes). Of the four plant groups tested, extracts from the popular antimicrobial-remedy group were significantly more effective at inhibiting fungal growth based on both overall antifungal activity and number of fungal species inhibited.