Patterns of nucleotide misincorporations during enzymatic amplification and direct large-scale sequencing of ancient DNA

Whereas evolutionary inferences derived from present-day DNA sequences are by necessity indirect, ancient DNA sequences provide a direct view of past genetic variants. However, base lesions that accumulate in DNA over time may cause nucleotide misincorporations when ancient DNA sequences are replicated. By repeated amplifications of mitochondrial DNA sequences from a large number of ancient wolf remains, we show that C/G-to-T/A transitions are the predominant type of such misincorporations. Using a massively parallel sequencing method that allows large numbers of single DNA strands to be sequenced, we show that modifications of C, as well as to a lesser extent of G, residues cause such misincorporations. Experiments where oligonucleotides containing modified bases are used as templates in amplification reactions suggest that both of these types of misincorporations can be caused by deamination of the template bases. New DNA sequencing methods in conjunction with knowledge of misincorporation processes have now, in principle, opened the way for the determination of complete genomes from organisms that became extinct during and after the last glaciation.

A quantitative genomic expression analysis platform for multiplexed in vitro prediction of drug action

Genomic expression signatures provide high-content biomarkers of cellular physiology, including the diverse responses to therapeutic drugs. To recognize these signatures, we devised a method of biomarker evaluation called 'sampling over gene space' (SOGS) that imparts superior predictive performance to existing supervised classification algorithms. Applied to microarray data from drug-treated human cortical neuron 1A cell cultures, this method predicts whether individual compounds possess anticonvulsant, antihypertensive, cyclooxygenase inhibitor, or opioid action. Thus, stable cell lines can be suitable for expression signature-based screening of a diverse range of activities. A SOGS-based system also discriminates physiologically active from inactive compounds, identifies drugs with off-target side effects, and incorporates a quantitative method for assigning confidence to individual predictions that, at its most stringent, approaches 100% accuracy. The capacity to resolve multiple distinct drug activities while simultaneously discriminating inactive and potential false-positive compounds in a cell line presents a unified framework for streamlined chemical genomic drug discovery.

Detection of oncogenic mutations in the EGFR gene in lung adenocarcinoma with differential sensitivity to EGFR tyrosine kinase inhibitors

The complete sequencing of the human genome and the development of molecularly targeted cancer therapy have promoted efforts to identify systematically the genetic alterations in human cancer. By high-throughput sequencing of tyrosine kinase genes in human non-small-cell lung cancer, we identified somatic mutations in the kinase domain of the epidermal growth factor receptor tyrosine kinase gene (EGFR) that are correlated with clinical response to EGFR tyrosine kinase inhibitors (TKIs). We have shown that these mutant forms of EGFR induce oncogenic transformation in different cellular systems. Cells whose growth depends on EGFR with mutations in exons 19 and 21 are sensitive to EGFR-TKIs, whereas cells expressing insertion mutations in exon 20 or the T790M point mutant, found in tumor biopsies from patients that relapsed after an initial response to EGFR-TKIs, are resistant. Furthermore, by applying a novel, massively parallel sequencing technology, we have shown that clinically relevant oncogene mutations can be detected in clinical specimens with very low tumor content, thereby enabling optimal patient selection for mutation-directed therapy. In summary, by applying high-throughput genomic resequencing, we have identified a novel therapeutic target, mutant EGFR, in lung cancer and evaluated its role in predicting response to targeted therapy.

A protein interaction map of Drosophila melanogaster

Drosophila melanogaster is a proven model system for many aspects of human biology. Here we present a two-hybrid-based protein-interaction map of the fly proteome. A total of 10,623 predicted transcripts were isolated and screened against standard and normalized complementary DNA libraries to produce a draft map of 7048 proteins and 20,405 interactions. A computational method of rating two-hybrid interaction confidence was developed to refine this draft map to a higher confidence map of 4679 proteins and 4780 interactions. Statistical modeling of the network showed two levels of organization: a short-range organization, presumably corresponding to multiprotein complexes, and a more global organization, presumably corresponding to intercomplex connections. The network recapitulated known pathways, extended pathways, and uncovered previously unknown pathway components. This map serves as a starting point for a systems biology modeling of multicellular organisms, including humans.

The characterization of PPAR alpha ligand drug action in an in vivo model by comprehensive differential gene expression profiling

Expression pharmacogenomics includes differential gene expression (DGE) profiling of drug responses in model systems to generate a set of differentially modulated drug-responsive genes which can serve as a surrogate measure for drug action. In this manner, expression pharmacogenomics bridges the fields of genomics and medicinal chemistry. Additionally, modulated genes can be organized into metabolic and signaling pathways that highlight the mechanism of drug activity in a selected tissue. Here, we describe the application of expression pharmacogenomics to characterize a drug response in the clinically relevant in vivo model, the Sprague-Dawley rat. Following oral dosing of rats with GW9578, a novel synthetic peroxisome proliferator activated receptor alpha (PPAR alpha) ligand indicated for lipid disorders, we applied GeneCalling, a differential mRNA transcript profiling technique, to rat liver cDNA. Following GW9578 treatment, 2.4% of the rat liver genes were differentially expressed. We confirmed the sequence identity of 50 distinctly modulated genes. DGE was observed among genes representative of at least six discrete metabolic pathways. Furthermore, we observed up-regulation of 20 genes involved in mitochondrial, peroxisomal and microsomal fatty acid oxidation, consistent with molecular biological and clinical data indicating PPAR alpha ligand principal efficacy to be through increasing fatty acid metabolism. Those pathways regulated in our study that are potentially contributory to target effect, non-target adverse effects, or of unknown consequence include xenobiotic detoxification and steroid modification. Finally, comprehensive drug response profiling can lead to the serendipitous discovery of novel disease indications. In this case, these results suggest a potential novel indication for GW9578 in the treatment of X-linked adrenoleukodystrophy. We have shown, therefore, that the organization of DGE results into metabolic and signaling pathways can elucidate mechanisms of pharmacologically desired (i.e., efficacious) and, where appropriate, undesired (i.e., potentially deleterious) effects.

PDGF-D, a new protease-activated growth factor

Platelet-derived growth factor (PDGF) has been directly implicated in developmental and physiological processes, as well as in human cancer, fibrotic diseases and arteriosclerosis. The PDGF family currently consists of at least three gene products, PDGF-A, PDGF-B and PDGF-C, which selectively signal through two PDGF receptors (PDGFRs) to regulate diverse cellular functions. After two decades of searching, PDGF-A and B were the only ligands identified for PDGFRs. Recently, however, database mining has resulted in the discovery of a third member of the PDGF family, PDGF-C, a functional analogue of PDGF-A that requires proteolytic activation. PDGF-A and PDGF-C selectively activate PDGFR-alpha, whereas PDGF-B activates both PDGFR-alpha and PDGFR-beta. Here we identify and characterize a new member of the PDGF family, PDGF D, which also requires proteolytic activation. Recombinant, purified PDGF-D induces DNA synthesis and growth in cells expressing PDGFRs. In cells expressing individual PDGFRs, PDGF-D binds to and activates PDGFR-beta but not PDGFR-alpha. However, in cells expressing both PDGFRs, PDGF-D activates both receptors. This indicates that PDGFR-alpha activation may result from PDGFR-alpha/beta heterodimerization.

Implications of oncogenomics for cancer research and clinical oncology

The explosion of information generated by large-scale functional genomics technologies has resulted in an exponential increase in the number of potential genes and proteins available for pharmaceutical and diagnostic research development. In order to tap this potential, the primary challenge is to develop a strategy to effectively integrate and extract meaning from the human genomic sequence information that has been generated since the start of the Human Genome Project. This article deals with the strategies being applied by academics and by the biotechnology sector to sort and triage this information with the ultimate goal of identifying future therapeutic targets for cancer and other diseases.

A comprehensive analysis of protein-protein interactions in Saccharomyces cerevisiae

Two large-scale yeast two-hybrid screens were undertaken to identify protein-protein interactions between full-length open reading frames predicted from the Saccharomyces cerevisiae genome sequence. In one approach, we constructed a protein array of about 6,000 yeast transformants, with each transformant expressing one of the open reading frames as a fusion to an activation domain. This array was screened by a simple and automated procedure for 192 yeast proteins, with positive responses identified by their positions in the array. In a second approach, we pooled cells expressing one of about 6,000 activation domain fusions to generate a library. We used a high-throughput screening procedure to screen nearly all of the 6,000 predicted yeast proteins, expressed as Gal4 DNA-binding domain fusion proteins, against the library, and characterized positives by sequence analysis. These approaches resulted in the detection of 957 putative interactions involving 1,004 S. cerevisiae proteins. These data reveal interactions that place functionally unclassified proteins in a biological context, interactions between proteins involved in the same biological function, and interactions that link biological functions together into larger cellular processes. The results of these screens are shown here.

Differential transport of DNA by a rectified Brownian motion device

An interdigitated electrode array (IDEA) device has been designed and used to transport DNA based on a Brownian ratchet mechanism. This migration is produced by the periodic formation of an asymmetric sawtooth electric field in the device. Oligonucleotides of 25, 50, and 100 bases in length were tested using two different array geometries. DNA transport as a function of DNA size, electric field frequency, and array geometry is shown to be in qualitative agreement with theory. Such a device could provide for DNA separations over a broad size range, and can be readily scaled as a component in a microfabricated DNA analysis system.

A transmission imaging spectrograph and microfabricated channel system for DNA analysis

In this paper we present the development of a DNA analysis system using a microfabricated channel device and a novel transmission imaging spectrograph which can be efficiently incorporated into a high throughput genomics facility for both sizing and sequencing of DNA fragments. The device contains 48 channels etched on a glass substrate. The channels are sealed with a flat glass plate which also provides a series of apertures for sample loading and contact with buffer reservoirs. Samples can be easily loaded in volumes up to 640 nL without band broadening because of an efficient electrokinetic stacking at the electrophoresis channel entrance. The system uses a dual laser excitation source and a highly sensitive charge-coupled device (CCD) detector allowing for simultaneous detection of many fluorescent dyes. The sieving matrices for the separation of single-stranded DNA fragments are polymerized in situ in denaturing buffer systems. Examples of separation of single-stranded DNA fragments up to 500 bases in length are shown, including accurate sizing of GeneCalling fragments, and sequencing samples prepared with a reduced amount of dye terminators. An increase in sample throughput has been achieved by color multiplexing.

DNA transport by a micromachined Brownian ratchet device

We have micromachined a silicon-chip device that transports DNA with a Brownian ratchet that rectifies the Brownian motion of microscopic particles. Transport properties for a DNA 50-mer agree with theoretical predictions, and the DNA diffusion constant agrees with previous experiments. This type of micromachine could provide a generic pump or separation component for DNA or other charged species as part of a microscale lab-on-a-chip. A device with reduced feature size could produce a size-based separation of DNA molecules, with applications including the detection of single-nucleotide polymorphisms.

Gene expression analysis by transcript profiling coupled to a gene database query

We describe an mRNA profiling technique for determining differential gene expression that utilizes, but does not require, prior knowledge of gene sequences. This method permits high-throughput reproducible detection of most expressed sequences with a sensitivity of greater than 1 part in 100,000. Gene identification by database query of a restriction endonuclease fingerprint, confirmed by competitive PCR using gene-specific oligonucleotides, facilitates gene discovery by minimizing isolation procedures. This process, called GeneCalling, was validated by analysis of the gene expression profiles of normal and hypertrophic rat hearts following in vivo pressure overload.

The Army psychological autopsy: then and now

The conduct and reporting of an Army psychological autopsy is a complex and relatively infrequent event. The details of these reports may not be completely clear to the behavioral sciences personnel tasked with collecting the data. This paper reviews the current status of the Army psychological autopsy and contrasts it with the development of civilian psychological autopsies. The current thinking of the Department of Defense Health Affairs working group on psychological autopsies is presented. The epidemiological content of the Army psychological autopsy as a scientific resource is presented in the form of an analysis of the psychological autopsies for the 1995 Army suicide data. Suggestions for updating this unique command tool are included.

Phase II trial of recombinant human interleukin-2 and interferon-alpha-2a: implications for the treatment of patients with metastatic melanoma

BACKGROUND

An intensive in-patient Phase II study of continuous infusion recombinant human interleukin-2 (rhIL-2) 3 X 10(6) Roche units (9 MIU/m2)/day plus intramuscular injection of interferon-alpha-2a (rIFN-alpha-2a) 5 x 10(6) U/m2/day, four consecutive days per week, was performed to determine whether four consecutive weeks of treatment every 6 to 8 weeks might yield a response rate of 30 to 40%, supporting an additive or synergistic effect of these agents in patients with metastatic melanoma.

METHODS

Eligibility was limited to otherwise healthy metastatic melanoma patients with no brain metastases. Tumor sites were measured at six-week intervals. Toxicity was recorded using the National Cancer Institute's common toxicity criteria.

RESULTS

From 1988 through 1989, 23 patients received 47 courses of rhIL-2 plus rIFN-alpha-2a. Fifteen patients (65%) had visceral metastases. Eight patients (35%) had prior systemic chemotherapy. There were two partial responses, both after one course, for a response rate of 8% (95% confidence interval: 1% to 28%). A previously untreated patient had more than 90% diminution in extensive liver, adrenal, duodenal, and soft tissue metastases lasting 9 months. A second patient, who had failed prior chemotherapy, had a 50% reduction in lymph node metastases lasting 8 months. Median overall survival was 10.4 months (21 and 70+ months for the two responders). Cumulative reversible toxicities of debilitating fatigue, malaise, depression, poor appetite, and acute toxicities of hypotension, oliguria, infection, and cortical dysfunction were responsible for dose modifications in 16% of 188 anticipated weeks of treatment, usually near the end of the second or subsequent treatment courses.

CONCLUSIONS

This study demonstrates a low response rate and lack of additive benefit for rhIL-2 and rIFN-alpha-2a administered intensively in metastatic melanoma patients. Since this biotherapy regimen, in the same dose and weekly schedule, has yielded substantial clinical activity with chemotherapeutic agents, this activity cannot be significantly attributed to the independent activity of rhIL-2 plus rIFN-alpha-alone.

Ambulatory mental health services at a U.S. Army combat support post: the effects of the Persian Gulf War

A study of ambulatory mental health services on a U.S. Army post where logistic support personnel are stationed compared utilization of psychiatric services before, during, and after the Persian Gulf War. Rates were calculated for service utilization for the at-risk groups from consecutive cases presenting at the post's ambulatory mental health services in the Department of Psychiatry. Our findings include a high rate of dysfunction for soldiers in training during the war; significant age, race, and sex differences between utilizers and non-utilizers throughout the study period; increased routine evaluations for military schools following the war; and significant increases in utilization of services by identified high-stress units during this conflict. Rates of utilization for a combat support post can be used for resource allocation and have implications for mental health manpower planning and stress prevention.

Mobilization and rejection of Individual Ready Reserve personnel in Operations Desert Shield/Storm at a U.S. Army Quartermaster post

The individual Ready Reserve (IRR) is an important component of the U.S. Army's total combat force. After Operations Desert Shield/Storm, we investigated the mobilization of soldiers with combat service support specialties from the IRR to a quartermaster training post. In the initial 2 weeks of activation prior to assignment and deployment, the soldiers went through medical and administrative screening, and general and specialized military training. During this period, a sizable portion (one-quarter) of IRR troops who reported to duty were rejected for a variety of reasons (overweight, inadequate dependent arrangements, etc.) and did not remain on active duty. Potential changes to the policies that led to these rejections are discussed.

Use of inpatient psychiatric services on a U.S. Army combat support post during Operations Desert Shield and Desert Storm: the stress of non-deployment

We studied the utilization of inpatient psychiatric services during Operations Desert Shield and Desert Storm (the Persian Gulf War of 1990-1991) on a U.S. Army combat support post. Inpatient psychiatric admissions and dispositions for the post's catchment area were tallied before, during, and after Operations Desert Shield and Desert Storm. Subjects included active duty soldiers (deployed soldiers were not studied while they were away from the post), their families, and retirees. Overall, there was no increase in psychiatric hospitalizations for active duty soldiers, their family members, or retirees. However, coincident with the return of soldiers from Operations Desert Shield and Desert Storm, the psychiatric proportion of all hospitalizations increased in the subpopulation of soldiers not deployed who had served less than 1 year. These soldiers in training may be more susceptible to increased stress levels associated with the return of soldiers from war because of their inadequate group bonding.

Compliance with consultations in a military psychiatry clinic

The study was undertaken to determine the effect of increased information in the referral process on compliance in routine consultations to a military outpatient psychiatry clinic. To evaluate the potential beneficial effects of facilitating factors in a clinic with over 70% baseline compliance, the psychiatrist's name and information about the clinic was provided to one-half of all patients who presented with a routine consult during a 2-month period. There was no increase in compliance rates for patients who were given more than standard information. These results have impact on manpower and staffing issues for the military.

Desert Shield deployment and social problems on a U.S. Army combat support post

We undertook a study of selected mental health-related services at a combat support post to determine if stress levels surrounding Operations Desert Shield/Desert Storm had an effect on the utilization of these services. Our measure was the problem rate formed by adding the visits to the alcohol and drug service and the social work service. The findings (not all of which reached statistical significance in our small study) were that the problem rates were higher in those units which deployed, both before and after deployment. The pre-deployment differences in age, rank, and race between those soldiers deployed and not deployed is a finding which may help to account for the difference between units. There was a transient, but not sustained, problem rate increase immediately following return home for those units which deployed. Implications for mental health-related services staffing and directions for further research are discussed.

Witnessed suicides

Suicides that take place in the presence of others have not been the topic of systematic scientific inquiry. The so-called witnessed suicides account for a small percentage of all suicides but offer a unique view into the dynamics of self-destructive behavior. An epidemiologic and forensic description of 50 witnessed suicides drawn from a 15-year series of over 1,000 cases is presented. A taxonomy is developed based on the role played by the witness and related to previous work on self-destructive behavior and its motivation. Brief vignettes are used to illustrate some of the interpersonal dynamics associated with these deaths.

Modularity of the slit protein. Characterization of a conserved carboxy-terminal sequence in secreted proteins and a motif implicated in extracellular protein interactions

Since our characterization of the slit cDNA sequence, encoding a protein secreted by glial cells and involved in the formation of axonal pathways in Drosophila, we have discovered that the protein contains two additional sequence motifs that are highly conserved in a variety of proteins. A search of the GenPept database with the 73 amino acids at the carboxy terminus of slit revealed that this region contains significant similarity to a carboxy-terminal domain found in six other exported proteins. This observation has allowed us to define a new carboxy-terminal protein motif. In addition, comparisons with a 202 amino acid domain residing between epidermal growth factor (EGF) repeats in slit shows this region to be conserved in laminin, agrin and perlecan and, strikingly, also to lie between EGF repeats in both agrin and perlecan. Our analysis suggests this motif is involved in mediating interactions among extracellular proteins. Consistent with our previous characterization of the slit protein, both new motifs are found only in extracellular proteins. The identification of these two conserved motifs in slit reveals that the entire 1469 amino acids of the protein are made up of modular regions similar to those conserved in other extracellular proteins.

Parasuicidal behavior on an active duty army training post

The incidence of suicidal behavior among active duty Army personnel at a training post has not been the subject of analysis since the advent of the all-volunteer military. A review of admissions over 16 consecutive months showed most of the behaviors to be parasuicidal, with low levels of lethality and high rescuability. Compared to previously published studies, the characteristics of these soldiers are little changed over the past 25 years. This report suggests a standard method for handling suicidal behavior which includes an active role for psychiatric consultation to units and commanders.

A phase I trial of recombinant alpha-2a interferon (Roferon-A) with weekly cisplatinum

Eighteen patients with advanced solid tumors were treated in a phase I study of cisplatinum in combination with recombinant alpha-2a interferon (Roferon-A, Hoffman-LaRoche, Inc, Nutley, NJ). Roferon-A was administered at a dose of 5 MU/m2 S.C. three times a week and the dose levels of cisplatinum were 15, 20, 25, 33, and 42 mg/m2/week given intravenously. All patients experienced grade I/II fatigue, nausea and vomiting. Grade III toxicity occurred in 4/6 patients at dose level 4. The dose limiting toxicities were myelosuppression [leukopenia (two patients), neutropenia (one patient), thrombocytopenia (one patient)], vomiting (one patient) and severe fatigue leading to a decrease in performance status (one patient). One patient with non-small cell lung carcinoma had a mixed response and another a minor response. The recommended dose level of this combination for phase II studies is cisplatinum 25 mg/m2/week and Roferon-A 5 MU/m2 three times a week.

slit: an extracellular protein necessary for development of midline glia and commissural axon pathways contains both EGF and LRR domains

The Drosophila slit locus encodes a protein with four regions containing tandem arrays of a 24-amino-acid leucine-rich repeat (LRR) with conserved flanking sequences (flank-LRR-flank surrounding these arrays), followed by two regions with epidermal growth factor (EGF)-like repeats. Each of these motifs has been implicated in protein-protein interactions as part of an extracellular domain in a variety of other proteins. Analysis of slit cDNA clones reveals that as a consequence of alternative splicing, the locus can code for two distinct protein species differing by 11 amino acids at the carboxyl terminus of the last EGF repeat. The existence of a putative signal sequence and the absence of a transmembrane domain suggest that slit is secreted, an observation supported by an analysis of its expression in tissue culture. Examining the expression pattern of slit in the embryo by antibody staining, enhancer trap detection, and in situ hybridization, we demonstrate that the protein is expressed by a subset of glial cells along the midline of the developing central nervous system. Through immunoelectron microscopy, slit can be seen on the commissural axons traversing the glial cells although it is absent from the cell bodies of these neurons, implying that slit is exported by the glia and distributed along the axons. Finally, we demonstrate that a reduction in slit expression results in a disruption of the developing midline cells and the commissural axon pathways. The embryonic localization, mutant phenotype, and homology of slit to both receptor-binding EGF-like ligands and adhesive glycoproteins suggest that it may be involved in interactions between the midline glial cells, their extracellular environment, and the commissural axons that cross the midline.

Life and death in the US Army. In Corpore sano

Using standardized mortality ratios, this study compares the sex- and race-specific, age-adjusted death rates for all US Army soldiers with those for the entire US population. Results show that soldiers are currently dying at a rate that is only half that of their civilian counterparts. The most striking difference in death rates by cause is a markedly lower homicide death rate for Army black men; homicides among the civilian black male population are 12 times more frequent than in the Army. Some factors that might account for these lower mortality rates in the Army are discussed.

Suicide in United States Army personnel, 1985-1986

A sixth biennium of epidemiological data on suicide in the U.S. Army was compiled. The annual crude suicide rate per 100,000 soldiers-at-risk for 1985-1986 was found to be 13.8, an increase of 3.8 points from 1983-1984. Sex-specific, race-specific, age-specific, grade-specific, and marital-status-specific rates were studied, and can be compared with the same indices in the previous six biennia. The standardized mortality ratio was calculated for 1986 and was found to be 69, significantly lower than the 100 expected from a civilian population of the same size and age-sex-race composition as the U.S. Army. Demographic data and information on circumstances surrounding the suicidal act were also made available for comparison with previous data. Analysis of the suicidal person's psychosocial situation (as reflected in the kinds of personal problems recorded in the reports and investigations of the incident and as reflected in assessment made of the victims presuicidal "motivational state") showed remarkable constancy in the five time periods studied, and indicates a powerful, consistent association between a dyadic love-object relationship in total collapse and the completed suicide.

Dealing with the stress of an HIV-positive diagnosis at an Army medical center

Following mandatory military-wide testing for the human immunodeficiency virus (HIV), Army medical facilities have gained extensive experience with HIV-positive persons who undergo special stresses as a result of their affiliation with the military. The consequences of evacuation to medical centers for evaluation of HIV status are presented and the impact of this process on the medical center staff are considered. This paper is a description of one system designed to evaluate, treat, and support HIV-positive soldiers and their families.

Concomitant administration of recombinant human interleukin-2 and recombinant interferon alpha-2A in cancer patients: a phase I study

Twenty-seven patients with metastatic cancer were treated with a daily continuous intravenous (IV) infusion of recombinant human interleukin-2 (rhIL-2) along with daily intramuscular recombinant interferon-alpha-2a (rIFN-alpha-2a) 4 days per week for 4 weeks with repeated treatment after 2 to 4 weeks of rest. The maximum-tolerated dose (MTD) was 3 million U/m2/d of rhIL-2 with 5 to 10 million U/m2/d of rIFN-alpha-2a. The dose-limiting toxicities are moderate hypotension requiring low doses of pressors and chronic fatigue associated with decreased performance status. Other common side effects included fever, chills, fluid retention, nausea/vomiting, erythrodermia, weight loss, elevated liver transminase levels, anemia, thrombocytopenia, and CNS toxic effects. There were seven objective responses among 25 evaluable patients. Four major responses (one complete response and three partial responses) were observed among 10 patients with melanoma treated with the MTD level. These data suggest that for cancer patients, concomitant rhIL-2 and rIFN-alpha-2a therapy is tolerable and has manageable side effects. Further phase II studies will be needed to define the antitumor activity of this combination.

slit: an EGF-homologous locus of D. melanogaster involved in the development of the embryonic central nervous system

A family of loci homologous to the EGF-like portion of Notch, a gene involved in neurogenesis, have been identified in D. melanogaster. The sequence, spatial, and temporal distribution of both RNA and protein of one of these loci suggest a possible role in the development of the central nervous system (CNS). In situ hybridization and antibody staining of embryos show initial localization in cells along the midline of the neuroepithelium. High level expression is restricted in the developing embryo to a subset of six midline glial cells abutting growing axons. Extracellular localization is suggested by the presence of EGF-like repeats in the deduced protein sequence and antibody staining. Cytological, immunocytochemical, genetic, and molecular data show that this gene corresponds to the slit locus. Mutations in this locus result in the collapse of the regular scaffold of commissural and longitudinal axon tracts in the embryonic central nervous system.

Suicide in the U.S. Army: epidemiological and periodic aspects

An overview of suicide in the U.S. Army is presented in two sections: (1) the epidemiology of U.S. Army suicides, based on biennium reports, and (2) the temporal aspects of those suicides compared with the data for the United States as a whole. A brief historical review documents some of the changes in contemporary military suicide rates compared to those of the past century. The cycles in the number of suicides by day of the week, day of the month, and the month of the year for the U.S. Army are computed and contrasted with those reported for the U.S. resident population.

A longitudinal study of military performance subsequent to civilian drug use

This study evaluates the military performance of soldiers who were identified by the Army's urine screening program as having used drugs at the time they reported for active duty. The study used prospectively defined cohorts of large size (over 1,600 urinalysis positive and over 2,400 urinalysis negative entering males) and used longitudinal outcome measures drawn from existing medical and personnel files. The major findings are that the urinalysis positive individuals were significantly more likely not to complete their tour of duty, were more likely to be hospitalized, and had more bed-days per hospitalization than their urinalysis negative fellow soldiers. In terms of cohorts entering the Army, however, minimal improvement in outcome was found by considering an entirely drug-free cohort (obtained by omitting the urinalysis positive individuals) compared to a random cohort which contained positives at the then current prevalence of 2 per cent.

An application of stepwise discriminant analysis to the characterization of military heroin dependents, illicit drug users, and psychiatric patients

This application of stepwise discriminant analysis explores a way to structure skewed-sample interview data, discusses some implications of the results and the conceptual limitations of assumptions about deviancy, and suggests a focus for future studies of the complex phenomena of drug abuse. The methodology differs from previous reports in that it uses a constant probability level, letting the computational procedure determine the number of significant variables. It also provides a method of determining the "chance" level (the amount of correct classification when there are no differences between the groups) so that the observed correct classification values may be usefully interpreted.

Addicted and nonaddicted drug users. A comparison of drug usage patterns

Adetailed analysis of drug usage patterns of 101 multidrug-using soldiers disclosed little differentiation between individuals with a history of heroin addiction (N=68) from demographically similar multidrug-using (but nonaddicted) peers (N=33). Prior to the onset of herion addiction, relatively few differences in drug usage patterns emerged between the two groups, and what differences there were indicated more extensive drug use and a more rapid progression of drug use among the nonaddicted users. A "stepping-stone hypothesis" of heroin addiction is refuted by these data. Differences in drug use emerge after the intiation of heroin. Within a few months after first heroin use, those who did not become addicted returned to their preheroin experimentation levels of drug taking while the addicted group maintained an escalating pattern of opiate use.