A comparison of global gene expression measurement technologies in Arabidopsis thaliana

Microarrays and tag-based transcriptional profiling technologies represent diverse but complementary data types. We are currently conducting a comparison of high-density in situ synthesized microarrays and massively-parallel signature sequencing (MPSS) data in the model plant, Arabidopsis thaliana. The MPSS data (available at http://mpss.udel.edu/at) and the microarray data have been compiled using the same RNA source material. In this review, we outline the experimental strategy that we are using, and present preliminary data and interpretations from the transcriptional profiles of Arabidopsis leaves and roots. The preliminary data indicate that the log ratio differences of transcripts between leaves and roots measured by microarray data are in better agreement with the MPSS data than the absolute intensities measured for individual microarrays hybridized to only one of the cRNA populations. The correlation was substantially improved by focusing on a subset of genes excluding those with very low expression levels; this selection may have removed noisy data. Future reports will incorporate more than 10 tissues that have been sampled by MPSS.

Sweet taste in man: a review

A greater understanding of the molecular mechanisms of sweet taste has profound significance for the food industry as well as for consumers. Understanding the mechanism by which sweet taste is elicited by saccharides, peptides, and proteins will assist science and industry in their search for sweet substances with fewer negative health effects. The original AH-B theories have been supplanted by detailed structural models. Recent identification of the human sweet receptor as a dimeric G-protein coupled receptor comprising T1R2 and T1R3 subunits has greatly increased the understanding of the mechanisms involved in sweet molecule binding and sweet taste transduction. This review discusses early theories of the sweet receptor, recent research of sweetener chemoreception of nonprotein and protein ligands, homology modeling, the transduction pathway, the possibility of the sweet receptor functioning allosterically, as well as the implications of allelic variation.

In vitro binding assays using (3)H nisoxetine and (3)H WIN 35,428 reveal selective effects of gonadectomy and hormone replacement in adult male rats on norepinephrine but not dopamine transporter sites in the cerebral cortex

The prefrontal cortices mediate cognitive functions that critically depend on local dopamine levels. In male rats, many prefrontal tasks where performance is disrupted by changes in dopamine signaling are also impaired by gonadectomy, a manipulation that increases cortical dopamine concentration, prefrontal dopamine axon density and possibly extracellular prefrontal dopamine levels as well. Because these actions could be responsible for the impairing effects of gonadectomy on prefrontal function, the question of how they might arise comes to the fore. Accordingly, the present studies asked whether dopamine levels might be increased via a hormone sensitivity of transporter-mediated dopamine uptake. Specifically, (3)H WIN 35,428 and (3)H nisoxetine, ligands selective for the dopamine (DAT)- and norepinephrine transporter (NET) respectively, were used in in vitro binding assays to ask whether gonadectomy altered transporter affinity (Kd) and/or binding site number (Bmax) in prefrontal cortex, sensorimotor cortex and/or caudate. Assays performed on tissues dissected from sham-operated, gonadectomized and gonadectomized rats supplemented with testosterone propionate or estradiol for 4 or 28 days revealed no significant group differences or obvious trends in Kd or Bmax for DAT binding or in measures of Bmax for NET binding. However, affinity constants for (3)H nisoxetine were found to be significantly higher in sensorimotor and/or prefrontal cortex of rats gonadectomized and gonadectomized and supplemented with estradiol for 4 or 28 days but similar to control in gonadectomized rats given testosterone. Because the NET contributes substantially to extracellular prefrontal dopamine clearance, these androgen-mediated effects could influence prefrontal dopamine levels and might thus be relevant for observed effects of gonadectomy on dopamine-dependent prefrontal behaviors. A hormone sensitivity of the NET could also have bearing on the prefrontal dopamine dysfunction seen in disorders like schizophrenia that disproportionately affect males, whose severity correlates with abnormal testosterone levels, and for which the NET is among suspected sites of pathology.

Spatiotemporal expression control correlates with intragenic scaffold matrix attachment regions (S/MARs) in Arabidopsis thaliana

Scaffold/matrix attachment regions (S/MARs) are essential for structural organization of the chromatin within the nucleus and serve as anchors of chromatin loop domains. A significant fraction of genes in Arabidopsis thaliana contains intragenic S/MAR elements and a significant correlation of S/MAR presence and overall expression strength has been demonstrated. In this study, we undertook a genome scale analysis of expression level and spatiotemporal expression differences in correlation with the presence or absence of genic S/MAR elements. We demonstrate that genes containing intragenic S/MARs are prone to pronounced spatiotemporal expression regulation. This characteristic is found to be even more pronounced for transcription factor genes. Our observations illustrate the importance of S/MARs in transcriptional regulation and the role of chromatin structural characteristics for gene regulation. Our findings open new perspectives for the understanding of tissue- and organ-specific regulation of gene expression.

Scaffold/matrix attachment regions (S/MARs) are AT-rich DNA sequences that mediate structural organization of the chromatin within the nucleus. These elements constitute anchor points of the DNA for the chromatin scaffold and serve to organize the chromatin into structural domains. Studies on individual genes led to the conclusion that the dynamic and complex organization of the chromatin mediated by S/MAR elements plays an important role in the regulation of gene expression. In addition to intergenic S/MARs, which likely exert import insulator effects, more than 2,000 intragenic S/MARs have been shown to be present within the Arabidopsis genome. In this study, the authors set out to analyze the effects of these intragenic S/MAR elements on the regulation of the genes affected. Making use of exhaustive and multidimensional expression datasets available for Arabidopsis, the authors analyzed overall expression differences and correlation of intragenic S/MARs with spatiotemporal expression of genes. On a genome scale, pronounced tissue- and organ-specific and developmental expression patterns of S/MAR-containing genes have been detected. Notably, transcription factor genes contain a significant higher portion of S/MARs. The pronounced difference in expression characteristics of S/MAR-containing genes emphasizes their functional importance and the importance of structural chromosomal characteristics for gene regulation in plants as well as within other eukaryotes.

Geriatric mental health services research: Strategic Plan for an Aging Population: Report of the Health Services Work Group of the American Association for Geriatric Psychiatry

In November 1999, a working group of the American Association for Geriatric Psychiatry (AAGP) convened to consider strategic recommendations for developing geriatric mental health services research as a scientific discipline. The resulting consensus statement summarizes the principles guiding mental health services research on late-life mental disorders, presents timely and topical priorities for investigation with the potential to benefit the lives of older adults and their families, and articulates a systematic program for expanding the supply of well-trained geriatric mental health services researchers. The agenda presented here is designed to address critical questions in provision of effective mental health care to an aging population and the health policies that govern its delivery.

Pneumocystis carinii pneumonia prophylaxis with atovaquone in trimethoprim-sulfamethoxazole-intolerant orthotopic liver transplant patients: a preliminary study

Pneumocystis carinii pneumonia (PCP) is an opportunistic infection associated with increased morbidity and mortality in solid-organ and bone-marrow transplant recipients. Side effects of trimethoprim-sulfamethoxazole (TMP/SMX) are frequent; therefore, we performed a preliminary study using atovaquone suspension, 750 mg once daily, for 1 year for the prevention of PCP in liver transplant recipients intolerant to TMP/SMX therapy. Twenty-eight patients were treated, and data were analyzed for efficacy and toxicity. Adverse events occurred in 14 subjects, mainly related to the gastrointestinal tract. Side effects from TMP/SMX, i.e., rash, completely resolved and bone-marrow suppression improved in 62% of patients. No patients developed Pneumocystis carinii infection. Although a lower dose of atovaquone once daily may be effective in transplant recipients, further studies are necessary to confirm this preliminary observation. Liver Transpl 2001;7:750-751.)

A multicenter, open-label, prospective, randomized, dose-ranging pharmacokinetic study of the anti-TNF-alpha antibody afelimomab in patients with sepsis syndrome

OBJECTIVE

To investigate the pharmacokinetics and safety of afelimomab, a murine antibody fragment against human tumor necrosis factor (TNF)-alpha in patients with sepsis.

DESIGN

Multicenter, randomized, open-label, placebo-controlled phase I/II clinical trial.

SETTING

Intensive care units of six academic medical centers in the United States.

PATIENTS

Forty-eight patients with a clinical diagnosis of sepsis who received standard supportive care and antimicrobial therapy.

INTERVENTIONS

Patients received 0.3, 1.0, or 3.0 mg/kg afelimomab or placebo intravenously over 20 min. Three patients in each dose group received single doses; the remaining nine patients in each group received multiple (nine) doses at 8-h intervals over 72 h.

MEASUREMENTS AND MAIN RESULTS

Afelimomab appeared safe and well tolerated. Single- and multiple-dose kinetics were predictable and dose related. The elimination half-life was 44.7 h. Afelimomab treatment resulted in increased serum concentrations of TNF (includes TNF-antibody complexes) and decreased serum interleukin-6 concentrations, whereas no discernible trends were observed in placebo-treated patients. There was no significant treatment effect on 28-day mortality as was expected given the small number of patients. However, overall mortality was significantly (p = 0.001) associated with baseline interleukin-6 concentration. All patients experienced adverse events, but the vast majority were considered unrelated to the study drug and demonstrated no apparent relationship to afelimomab dose. Although 41% of patients developed human anti-murine antibodies, there were no clinical sequelae.

CONCLUSIONS

Multidose therapy with afelimomab was safe, well tolerated, and had predictable linear kinetics. A large randomized trial comparing afelimomab to placebo in patients with well defined sepsis has recently been completed.

Schizophrenia and older adults. An overview: directions for research and policy

The Group for the Advancement of Psychiatry, Committee on Aging, believes that a crisis has emerged with respect to the understanding of the nature and treatment of schizophrenia in older persons. Moreover, critical gaps exist in clinical services for this population. In this article, we examine the epidemiology of aging and schizophrenia; life-course changes in psychopathology, cognitive function, social functioning, and physical health; and various concerns regarding treatment, services, and financing. Finally, we propose six research and policy recommendations and suggest methods for addressing the research questions that we have posed.

Selective decontamination of the digestive tract helps prevent bacterial infections in the early postoperative period after liver transplant

In liver transplant (LTx) recipients, gut-associated bacterial and fungal organisms produce significant postoperative morbidity and mortality. We sought to assess the role of selective digestive decontamination (SDD) in preventing postoperative infections in a large single-center cohort of liver recipients transplanted under two non-simultaneous protocols. In 212 consecutive patients transplanted between 1/1/91 and 7/31/92, SDD (gentamicin 80 mg, polymyxin B 100 mg, nystatin suspension 10 mL) was employed, starting after induction of anesthesia and continued until POD 21 (SDD Group). In 157 consecutive patients transplanted between 1/1/93 and 12/31/93, SDD was not used (non-SDD Group). Both groups received IV vancomycin and cefotaxime prophylaxis. All culture-positive infections within the first 30 days post-LTx were recorded and classified as bacterial or fungal. Infection-related mortality (patients who died of infectious complications without any technical complication) was recorded. Groups did not differ in patient demographics, United Network for Organ Sharing (UNOS) status, use of veno-venous bypass, total/warm ischemia, or length of ICU stay. Infections developed in fewer SDD patients (56/212; 26%) than non-SDD patients (69/157; 44%) (p<0.001). The incidence of gram-negative infection was less in the SDD group (11% vs. 26%, p<0. 001) as was gram-positive infection (16% vs. 26%, p<0.001). Among patients who developed infection, there was no difference between groups in infections per patient. Primary graft non-function (PNF) developed in 20 SDD patients (7/20 had infections) and 8 non-SDD patients (6/8 had infections) (p=0.06). There were no differences in incidence of fungal infections or of infection-related mortality between groups. In the SDD group, there were fewer abdominal (p<0. 001), lung (p<0.001), wound (p<0.01), and urinary tract infections (p<0.05).

CONCLUSION

Use of SDD in liver recipients early after transplant was associated with significantly fewer infections in the early postoperative period.

Thrombin receptor expression and responsiveness of human monocytic cells to thrombin is linked to interferon-induced cellular differentiation

Human thrombin has been shown to stimulate monocyte chemotaxis, phagocytosis, and interleukin (IL8) production, but the mechanisms responsible for stimulation are not well defined. In some cells, thrombin stimulation of proliferation appears to require both cleavage of the proteolytically activated receptor for thrombin (PAR1) and activation of a nonproteolytically activated thrombin receptor (N-PAR), while in others activation of either receptor alone may be sufficient for stimulation. We, therefore, have initiated studies to address thrombin receptor expression and cell responsiveness to thrombin in interferon gamma (IFNgamma)-differentiated and nondifferentiated U937 monocytic cells. Northern blot analysis shows that PAR1 expression is upregulated upon differentiation. Experiments with biotinylated and 125I-thrombin show that specific thrombin binding is dramatically increased by differentiation although it is not clear if this binding is to PAR1 or to a separate binding component such as N-PAR which is present on fibroblasts and other cells. Addition of thrombin at concentrations of 1-10 microg/ml (30-300 nM, concentrations where specific thrombin binding is observed) stimulates proliferation of IFNgamma-differentiated U937 cells but not of undifferentiated U937 cells. Thrombin also stimulates interleukin-6 (IL6) production in IFNgamma-differentiated U937 cells. Moreover, thrombin induces high levels of IL6, interleukin-1beta (IL1beta), and tumor necrosis factor-alpha (TNF alpha) production by peripheral blood mononuclear cells (PBMC) and monocytes. These results show that differentiated U937 cells and mature PBMC are responsive to thrombin whereas nondifferentiated U937 are not. Further, this responsiveness appears to correlate with expression of PAR1 and to a dramatic increase in specific thrombin binding. That thrombin stimulates cytokine production and proliferation in populations of differentiated monocytes suggests that thrombin may be an important regulator of inflammation and wound healing.

Severe brachial plexus injury as a result of snowmobiling: a case series

BACKGROUND

Documented snowmobile-related fatalities and injuries have increased; however, reports of peripheral nerve injuries are rare.

METHODS

This case series describes a cluster of severe disabling brachial plexus injuries incurred during snowmobiling. Medical record abstraction was used to identify relevant patient and event characteristics.

RESULTS

All study patients were younger male snowmobile drivers. All incidents occurred at speeds in excess of 40 mph. Blood alcohol concentrations exceeded legal intoxication limits in most cases. Complete damage of the brachial plexus occurred in four of the six patients; severe disability occurred in all cases. Five of the six patients sustained associated orthopedic shoulder complex injuries.

CONCLUSION

This first report of severe peripheral nerve damage may signal the advent of more severe nonfatal snowmobile-related injuries that mimic motorcycle-related injuries, because the maximum attainable speeds of snowmobiles have increased. Surveillance of snowmobile-related injuries is warranted to identify the full spectrum of snowmobile injuries and recommend public safety measures.

Isoniazid hepatotoxicity after orthotopic liver transplantation

The hepatotoxic effects of isoniazid have been well described, but there have been no reports on the incidence of isoniazid-induced liver disease in patients who have received an orthotopic liver transplant. We retrospectively reviewed the records of 13 patients who received isoniazid after liver transplantation for either chemoprophylaxis or as part of a multidrug regimen for the treatment of Mycobacterium tuberculosis infection. Five of the 13 patients developed biochemical and histologic evidence of isoniazid hepatotoxicity. All five patients were on a multidrug regimen which included the administration of rifampin. No hepatotoxicity occurred in patients who received isoniazid alone or in conjunction with ethambutol for chemoprophylaxis. In conclusion, the incidence of isoniazid hepatotoxicity increased when the drug was used in conjunction with rifampin for the treatment of M. tuberculosis infection.

An animal model for human melanoma

Experimental animal models that are directly relevant to human melanoma are lacking. We propose the Angora goat as a potentially useful field model with experimental potential and to this end have examined the prevalence and site distribution of all skin cancers in 28 Angora goat herds in Queensland, Australia. The prevalence of benign melanocytic lesions (lentigines) and their experimental induction by sunlight were also investigated. Among 1731 goats over 2 years of age, 139 malignant skin tumors were excised from 95 affected animals. The prevalence of squamous cell carcinoma (SCC) was 3.8% and of melanoma, 2.2%. Main site of occurrence of melanoma (83%) was the dorsal surface of the ear; in contrast SCC occurred mostly (84%) on the perineum. Lentigines were darker and more prevalent on the exposed compared with the unexposed surface of the ear in Angoras, analogous to the higher prevalence of nevi on the exposed compared with the less exposed inner surface of the arm in humans. Lentigines, which were also found on the perineum though lighter in color than on the dorsal ear, were absent in young animals under 3 months but were numerous in 1-3 year olds. Furthermore in an experimental substudy eight goats, having one flank repeatedly shorn and the contralateral flank left unshorn, revealed consistently more solar lentigines on the shorn flank (P < 0.05) when both sides were examined after 9 months. Histopathological examination of paired skin biopsies from five of these goats also showed more abundant pigmentation in skin from the exposed, as compared with the unexposed flank. These findings indicate that sunlight induces tumors and lentigines in goats in a highly site-specific manner. The Angora goat model may suggest paradigms for explaining the site differences observed for human melanoma and may also be useful in the future clarification of molecular changes following carcinogenic levels of sun exposure.

Identification of PTSD in cancer survivors

The authors measured the rate and determinants of posttraumatic stress disorder (PTSD) in a group of cancer survivors. Patients who had a history of cancer diagnosis with at least 3 years since diagnosis, receiving no active treatment, such as chemotherapy or radiation, were interviewed (N = 27). Patients, who were part of the DSM-IV PTSD field trial, were compared with a community-based control group matched for age and socioeconomic status. One member of the survivor group (4%) and no members of the control group met criteria for current PTSD (NS). Six of the survivors (22%) and no control subjects met lifetime criteria (P < 0.02). Cancer patients have a higher rate of PTSD than found in the community. Symptoms closely resemble those of individuals who have experienced other traumatic events.

Posttraumatic stress disorder in mothers of pediatric cancer survivors

Prevalence of posttraumatic stress disorder (PTSD) in 24 mothers of pediatric cancer survivors was compared with its prevalence among 23 mothers of healthy children. Significantly more mothers of pediatric cancer survivors were diagnosed with lifetime PTSD. Significant differences were also found in lifetime arousal, as well as current and lifetime reexperience and avoidance symptom clusters. Significant difference existed in the distribution of the number of prediagnosis high-magnitude events experienced by the mothers diagnosed with current PTSD as compared with the prediagnosis experience of the mothers who were not diagnosed with current PTSD. Illness severity, level of perceived family and extrafamilial social support, and Symptom Checklist-90-Revised global severity index scores did not significantly differ in the PTSD-positive and PTSD-negative groups.

Disaster study of war

In the first part of this article I argue that war should be considered as a disaster. A brief historical review of the relationship of the field of disaster studies to military concerns is presented in an effort to demonstrate that, in fact, war has been a familiar subject in the field. I then consider definitions of disaster and conclude that war is easily accommodated by them. In the main section of the article I attempt to uncover distinctive characteristics of war by submitting war to analysis within well known sociological frameworks for disasters. Finally, some methodological considerations for the study of war disasters are presented.

Ofloxacin use in a geriatric population

The efficacy and safety of ofloxacin for the treatment of pneumonia, urinary infection and skin infections in the institutionalized elderly is being studied in a multicenter North American trial. The two study arms include an open, randomized, comparison of intravenous or oral ofloxacin with standard therapy in subjects requiring admission to acute care institutions, and an open study of oral ofloxacin in residents of chronic care facilities. To date 58 subjects have been enrolled with a mean age of 84 +/- 8 years. The preliminary observations from this ongoing multicenter study suggest that ofloxacin will be a safe and effective option for antimicrobial therapy in the treatment of these common infections in the institutionalized elderly.