Viral diversity and dynamics in an infant gut

Metagenomic sequencing of DNA viruses from the feces of a healthy week-old infant revealed a viral community with extremely low diversity. The identifiable sequences were dominated by phages, which likely influence the diversity and abundance of co-occurring microbes. The most abundant fecal viral sequences did not originate from breast milk or formula, suggesting a non-dietary initial source of viruses. Certain sequences were stable in the infant's gut over the first 3months of life, but microarray experiments demonstrated that the overall viral community composition changed dramatically between 1 and 2weeks of age.     

A field guide to eukaryotic circular single-stranded DNA viruses: insights gained from metagenomics

Despite their small size and limited protein-coding capacity, the rapid evolution rates of single-stranded DNA (ssDNA) viruses have led to their emergence as serious plant and animal pathogens. Recently, metagenomics has revealed an unprecedented diversity of ssDNA viruses, expanding their known environmental distributions and host ranges. This review summarizes and contrasts the basic characteristics of known circular ssDNA viral groups, providing a resource for analyzing the wealth of ssDNA viral sequences identified through metagenomics. Since ssDNA viruses are largely identified based on conserved rolling circle replication proteins, this review highlights distinguishing motifs and catalytic residues important for replication. Genomes identified through metagenomics have demonstrated unique ssDNA viral genome architectures and revealed characteristics that blur the boundaries between previously well-defined groups. Metagenomic discovery of ssDNA viruses has created both a challenge to current taxonomic classification schemes and an opportunity to revisit hypotheses regarding the evolutionary history of these viruses.     

Chemosensitivity of lymphocytes from patients with B-cell chronic lymphocytic leukemia to chlorambucil, fludarabine, and camptothecin analogs

Chemosensitivity of B lymphocytes, obtained from 65 patients with B- cell chronic lymphocytic leukemia (B-CLL), Rai stages 0 through IV, was determined using the MTT assay. The results were expressed by the drug concentration required for 50% inhibition of cell viability (IC50). The cytotoxicity of chlorambucil (CLB) was compared with that of fludarabine and the DNA topoisomerase I inhibitors, camptothecin, 9- aminocamptothecin, 10,11-methylenedioxy-20(S)-camptothecin (10,11-MDC) and 9-amino-10,11-methylenedioxy-20(S)-campthothecin (9-A-10,11-MDC), and topotecan. Considerable heterogeneity in sensitivity to CLB was observed, with a median IC50 of 40.5 mumol/L in untreated patients. B- CLL cells from patients treated with CLB had a significantly higher median IC50 of 86.0 mumol/L (P < .01). Untreated as well as CLB-treated patients were divided into two subsets. For the purpose of this study, B-CLL lymphocytes with an IC50 CLB of less than 61.0 mumol/L were designated as "sensitive" and those with an IC50 CLB of > or = 61.0 mumol/L were designated as "resistant." After baseline assays, 15 untreated patients received CLB; after treatment, the IC50 increased in B-CLL lymphocytes from 13 of 15 patients. The response to CLB treatment, determined by its effect on the absolute lymphocyte count and by the Eastern Cooperative Oncology Group clinical criteria, was significantly better in patients whose lymphocytes had an IC50 CLB of less than 61.0 mumol/L before therapy (P < .01). B-CLL lymphocytes also had a variable degree of sensitivity in vitro to each of the other drugs. There was significant cross-resistance between CLB and fludarabine (P < 0.01). Whereas only 29% of CLB-resistant B-lymphocyte specimens obtained from individual patients were sensitive to fludarabine in vitro, 52% and 67% of CLB-resistant lymphocyte samples were sensitive to 10,11-MDC and 9-A-10,11-MDC, respectively. We have previously reported that p53 gene mutations were associated with aggressive B-CLL and a poor prognosis. B lymphocytes from seven patients with these mutations were resistant to CLB, and five of six were resistant to fludarabine. Lymphocytes from four of seven were resistant to 10,11-MDC, and three of four were resistant to 9-A-10,11- MDC. This study implies that the MTT assay may be useful in identifying subsets of CLL patients resistant to conventional chemotherapy. However, definitive conclusions can not be drawn in view of the small number of patients studied prospectively. In addition, these results suggest the potential of camptothecin-based therapy for patients unresponsive to standard treatment.     

Identifying patients at risk for,and treatment of major psychiatric complications of cancer

A critically important aspect of supportive care in cancer is the prompt recognition and effective treatment of psychiatric complications. Psychiatric disorders such as depression, anxiety and delirium occur in a signifcant percentage of cancer patients, particularly as disease advances and as cancer treatments become more aggressive. This paper reviews factors that can be utilized to identify patients who are at increased risk for developing psychiatric complications, such as those with advanced disease, certain cancer treatments, uncontrolled physical symptoms, functional limitations, lack of social support, and past history of psychiatric disorder. Methods of diagnostic assessment and strategies for managing depression, anxiety, delirium and suicidal ideation are also reviewed.Presented as an invited lecture at the 6th International Symposium: Supportive Care in Cancer, New Orleans, La., USA, 2–5 March 1994     

DNA microarray technology for neonatal screening

Modern molecular biology, owing much to the Human Genome Initiative, has elucidated many of the genetic mechanisms underlying heritable metabolic disease. While the use of molecular methods has flourished in research laboratories, complexity and cost have limited their utility in newborn screening. Newborn blood cards provide high quality DNA samples able to provide reliable support to highly multiplexed polymerase chain reactions (PCR). New manufacturing processes have reduced the cost of DNA microarray technology to the point where it is a practical tool for population screening. In a single assay, a DNA microarray facilitates the co-detection of amplification products diagnostic for several genetic diseases. High throughput is achieved with automation at every step, from DNA extraction to detection of hybrids. We suggest that it is both feasible and practical to develop a first-tier newborn screening protocol based upon multiplex PCR and analysis of amplification products using DNA microarrays. Initial data utilizing the model systems of sickle cell disease, α-1-antitrypsin deficiency and Factor V Leiden will be reported.     

Parents'fear regarding fever and febrile seizures

In order to improve the effectiveness of information, we studied parents' perceptions and knowledge about fever and febrile seizures. A questionnaire study was carried out among the parents whose children (n = 230) participated in a randomized controlled trial of ibuprofen to prevent recurrent febrile seizures. Of the 230 parents, 181 (79%) responded to the questionnaire. Of all parents, 45% were afraid or very afraid of fever, which was strongly associated with being afraid of recurrent febrile seizures. Parents of children with a non-West European background were more afraid. The consequences of parental fear included frequent temperature measurements (25% measured five times per day or more), sleeping in the same room (24%) and 13% remained awake at night. Witnessing a febrile seizure is a frightening experience for parents; a majority thought that febrile seizures were harmful, because they look dangerous. Forty-seven percent thought that their child was dying during the initial febrile seizure. On the other hand, reassuring information may be helpful: 21% mentioned it as their reason to consider febrile seizures not harmful. We conclude that parental fear of fever and febrile seizures is a major problem with several negative consequences for daily family life. Adequate provision of information may reduce parental fear. We suggest that information about fever and febrile seizures should be provided to all parents, preferably during their contact with the providers of preventive healthcare. The parents of children with a non-West European origin need extra attention.