Twice-daily triple nucleoside intensification treatment with lamivudine-zidovudine plus abacavir sustains suppression of human immunodeficiency virus type 1: results of the TARGET Study

This open-label, multicenter, single-arm clinical trial assessed the 48-week efficacy of a twice-daily triple nucleoside reverse-transcriptase inhibitor regimen containing a lamivudine (150 mg)-zidovudine (300 mg) combination tablet (COM) and abacavir (ABC; 300 mg) in 87 antiretroviral therapy-experienced, protease inhibitor-naive patients infected with human immunodeficiency virus type 1 (HIV-1). At baseline, the median plasma HIV-1 RNA level was 3.10 log(10) copies/mL, and the median CD4 cell count was 506 cells/mm(3). An intent-to-treat&rcolon;observed analysis showed that, at weeks 24 and 48 of treatment, HIV-1 RNA level was <400 copies/mL in 48 (76%) of 63 and 45 (82%) of 55 patients, respectively, and <50 copies/mL in 37 (59%) of 63 and 31 (56%) of 55 patients, respectively. Previous zidovudine or lamivudine use and presence at baseline of the M184V reverse-transcriptase mutation did not impact virologic response. Median CD4 cell counts were maintained above baseline throughout the study. COM plus ABC was generally well tolerated.

Expanding the guidelines for electronic communication with patients: application to a specific tool

In 1998, the American Medical Informatics Association (AMIA) published a white paper entitled "Guidelines for the Clinical Use of Electronic Mail with Patients," which outlined a practical framework for this interaction. Interest in the use of other Internet-based tools, such as the World Wide Web, to enhance clinical communication is increasing. In such systems, static information can be made centrally available to patients and interactive tools such as messaging systems, schedules, and individualized care regimens can be integrated within the site. Site-specific guidelines are needed to address potential problems inherent in the particular services being offered. This article presents advice on developing site-specific guidelines, with examples, based on experience gained in developing and refining guidelines for the use of PatientWeb at the Massachusetts General Hospital Department of Neurology.

Phase I trial of XR9576 in healthy volunteers demonstrates modulation of P-glycoprotein in CD56+ lymphocytes after oral and intravenous administration

XR9576 is a novel inhibitor of P-glycoprotein (P-gp) that has been shown to reverse P-gp-dependent multidrug-resistance in tumor cell lines and tumor-bearing animals. Here we report the first i.v. and p.o. administration to healthy volunteers of XR9576 in dose-escalating studies with the aim of investigating its effects on safety, its pharmacokinetics, and a surrogate marker of efficacy. XR9576 was administered as a single dose-upward titration of 0.1, 0.2, 0.5, 1.0, and 2 mg/kg XR9576 i.v. or 50, 100, 200, 500, and 750 mg/volunteer p.o. The surrogate marker for in vivo efficacy examined the accumulation of the P-gp substrate Rhodamine-123 (Rh-123) in P-gp-expressing CD56+ lymphocytes by flow cytometry. Addition of Rh-123 to blood samples from subjects given XR9576 or a placebo demonstrated drug-dependent modulation of P-gp activity. Even at the lowest doses, significant effects were observed on Rh-123 accumulation in CD56+ cells. Maximal effects were seen during the i.v. infusion or 4-6 h after oral administration. As the dose was increased, a concomitant rise in the level and duration of P-gp blockade was observed. A dose of 2.0 mg/kg i.v. and > or = 200 mg/volunteer p.o. gave approximately 100% inhibition of P-gp for in excess of 24 h. All doses of XR9576 were well tolerated. Inhibition increased with XR9576 plasma concentration, and maximal activity was achieved at 150-200 ng/ml XR9576. In conclusion, XR9576 has demonstrated sustained inhibition of P-gp after i.v. and oral administration and, supported by the elimination half-life of about 24 h, XR9576 is being taken into Phase II as a once-daily agent.

Hsl7p, the yeast homologue of human JBP1, is a protein methyltransferase

The yeast protein Hsl7p is a homologue of Janus kinase binding protein 1, JBP1, a newly characterized protein methyltransferase. In this report, Hsl7p also is shown to be a methyltransferase. It can be crosslinked to [(3)H]S-adenosylmethionine and exhibits in vitro protein methylation activity. Calf histones H2A and H4 and bovine myelin basic protein were methylated by Hsl7p, whereas histones H1, H2B, and H3 and bovine cytochrome c were not. We demonstrated that JBP1 can complement Saccharomyces cerevisiae with a disrupted HSL7 gene as judged by a reduction of the elongated bud phenotype, and a point mutation in the JBP1 S-adenosylmethionine consensus binding sequence eliminated all complementation by JBP1. Therefore, we conclude the yeast protein Hsl7p is a sequence and functional homologue of JBP1. These data provide evidence for an intricate link between protein methylation and macroscopic changes in yeast morphology.

Merging information in speech recognition: feedback is never necessary

Top-down feedback does not benefit speech recognition; on the contrary, it can hinder it. No experimental data imply that feedback loops are required for speech recognition. Feedback is accordingly unnecessary and spoken word recognition is modular. To defend this thesis, we analyse lexical involvement in phonemic decision making. TRACE (McClelland & Elman 1986), a model with feedback from the lexicon to prelexical processes, is unable to account for all the available data on phonemic decision making. The modular Race model (Cutler & Norris 1979) is likewise challenged by some recent results, however. We therefore present a new modular model of phonemic decision making, the Merge model. In Merge, information flows from prelexical processes to the lexicon without feedback. Because phonemic decisions are based on the merging of prelexical and lexical information, Merge correctly predicts lexical involvement in phonemic decisions in both words and nonwords. Computer simulations show how Merge is able to account for the data through a process of competition between lexical hypotheses. We discuss the issue of feedback in other areas of language processing and conclude that modular models are particularly well suited to the problems and constraints of speech recognition.

Benign melanocytic proliferative nodule within a congenital naevus

A neonate presented with a deeply pigmented papule within a medium-sized congenital naevus. Histologically, this proved to be a benign proliferative nodule in a congenital naevus. This case is presented to highlight the occurrence of this lesion, the main differential of which is the rare entity of true congenital melanoma.

Evaluation of simplified protease inhibitor dosing regimens for the treatment of HIV infection

Complicated dosing regimens can unfavorably affect patient adherence and drug efficacy. In an effort to increase adherence while maximizing the benefits of the protease inhibitor (PI) component of HAART, the efficacy and safety of less frequent PI dosing regimens have recently been under scrutiny. Limiting the number of drugs required in antiretroviral therapy regimens may also minimize toxicity and drug-drug interactions. This article reviews the current movement toward twice-daily regimens and examines the efficacy and safety data available on twice-daily dosing of amprenavir, indinavir, nelfinavir, saquinavir soft-gel capsules, and ritonavir. Future trends in dosing are also discussed.

Yeast cell-free system that catalyses joint-molecule formation in a Rad51p- and Rad52p-dependent fashion

One of the central reactions of homologous recombination is the invasion of a single strand of DNA into a homologous duplex to form a joint molecule. Here we describe the isolation of a cell-free system from meiotic yeast cells that catalyses joint-molecule formation in vitro. The active components in the system required ATP and homologous DNA and operated in both 0.5 and 13 mM MgCl(2). When the cell-free system was prepared from rad51/rad51 and rad52/rad52 mutants and joint-molecule formation was assayed at 0.5 mM MgCl(2), the specific activity decreased to 6% and 13.8% respectively of the wild-type level. However, when the same mutant extracts were premixed, joint-molecule formation increased 4-8-fold, i.e. the mutant extracts exhibited complementation in vitro. These results demonstrated that Rad51p and Rad52p were required for optimal joint-molecule formation at 0.5 mM MgCl(2). Intriguingly, however, Rad51p and Rad52p seemed to be more dispensable at higher concentrations of MgCl(2) (13 mM). Further purification of the responsible activity has proven problematical, but it did flow through a sizing column as a single peak (molecular mass 1.2 MDa) that was co-eluted with Rad51p and RFA, the eukaryotic single-stranded DNA-binding protein. All of these characteristics are consistent with the known properties of the reaction in vivo and suggest that the new cell-free system will be suitable for purifying enzymes involved in homologous recombination.

Naming cAsE aLtErNaTeD words

A dual-route approach was used as an initial framework to examine the relation between presentation format and lexical processing in a naming task. In Experiments 1 and 3, words were presented in lowercase versus case-alternated format. Presentation format interacted with word frequency and regularity: For irregular words (e.g., pint), case alternation was additive with frequency, whereas for regular words (e.g., mint), case alternation and frequency interacted. Experiment 2 dissociated the locus of case-alternation effects from those of stimulus intensity. Stimulus intensity was additive with frequency and regularity, suggesting that whereas stimulus intensity affects encoding, case alternation affects lexical processing at a postencoding stage in the word recognition system. It was concluded that a dual-route approach provides a suggestive but incomplete account of how case alternation influences lexical processing. As an alternative to a dual-route approach, we show that the present results can be addressed and successfully simulated using an implemented version of Norris's (1994) multilevel model.

Information exchange in an epilepsy forum on the World Wide Web

The Partners Healthcare Epilepsy Service hosts an epilepsy 'Webforum'. In this paper, we describe our observations regarding who uses it, what kind of information is exchanged, how much misinformation is present and how we can better serve our patients. We examined a sample of 155 posts to the forum and 342 responses to those posts. The individual making the post and the type of questions were categorized. We also determined whether any information was objectively inaccurate. The principal users were care-givers (49%) and patients (34%). Eighty percent of the primary posts were questions. Answers were given largely by patients (38%) and care-givers (34%). The most commonly asked questions were about treatment options (31%) and the natural history of the illness (28%). In 20% of the questions, the user incidentally remarked that a health-care provider had not met their information needs. Six percent of the information was objectively inaccurate. The Web can serve as an effective means for the exchange of information between individuals with a common medical condition. We found that a small amount of misinformation is exchanged and that health-care providers are sometimes perceived as unable or unwilling to supply important health-related information.

Human acquired naevi are clonal

Naevi are nearly universal in humans, yet their cellular origin remains obscure. Understanding the cellular and molecular mechanisms involved in naevus development may be important in understanding the pathogenesis of malignant melanoma. This study aimed to discover whether human acquired naevi are premalignant by examining whether they are clonal. To determine clonality naevi were removed and separated into epithelial and naevus cell fractions and the DNA prepared and digested by a methylase-sensitive restriction enzyme. The highly polymorphic X-linked human androgen receptor (HUMARA) gene was then amplified by a polymerase chain reaction and examined by gel electrophoresis and autoradiography. In polyclonal cell populations both alleles are usually seen as two distinct bands, whilst clonal populations yield a single band. Using these techniques 35 junctional naevi, 11 compound naevi and one congenital naevus from 40 women were examined. Of these, 81% (37 out of 47) of the naevi were clonal, while all of the epithelial cell controls were polyclonal. These data are novel and have great importance for understanding the development of human acquired naevi and cutaneous malignant melanoma. Because monoclonality is a marker of neoplasia, or preneoplasia, our data support the hypothesis that common acquired naevi should be considered to be premalignant lesions, similar to colonic polyps. Such lesions may have undergone the first molecular step(s) in the development of cutaneous malignant melanoma. Understanding the events involved may lead to new methods of prevention and treatment.

The SFP1 gene product of Saccharomyces cerevisiae regulates G2/M transitions during the mitotic cell cycle and DNA-damage response

In eukaryotic cells, checkpoint pathways arrest cell-cycle progression if a particular event has failed to complete appropriately or if an important intracellular structure is defective or damaged. Saccharomyces cerevisiae strains that lack the SFP1 gene fail to arrest at the G2 DNA-damage checkpoint in response to genomic injury, but maintain their ability to arrest at the replication and spindle-assembly checkpoints. sfp1Delta mutants are characterized by a premature entrance into mitosis during a normal (undamaged) cell cycle, while strains that overexpress Sfp1p exhibit delays in G2. Sfp1p therefore acts as a repressor of the G2/M transition, both in the normal cell cycle and in the G2 checkpoint pathway. Sfp1 is a nuclear protein with two Cys2His2 zinc-finger domains commonly found in transcription factors. We propose that Sfp1p regulates the expression of gene products involved in the G2/M transition during the mitotic cell cycle and the DNA-damage response. In support of this model, overexpression of Sfp1p induces the expression of the PDS1 gene, which is known to encode a protein that regulates the G2 checkpoint.

The primacy model: a new model of immediate serial recall

A new model of immediate serial recall is presented: the primacy model. The primacy model stores order information by means of the assumption that the strength of activation of successive list items decreases across list position to form a primacy gradient. Ordered recall is supported by a repeated cycle of operations involving a noisy choice of the most active item followed by suppression of the chosen item. Word-length and list-length effects are attributed to a decay process that occurs both during input, when effective rehearsal is prevented, and during output. The phonological similarity effect is attributed to a second stage of processing at which phonological confusions occur. The primacy model produces accurate simulations of the effects of word length, list length, and phonological similarity.

The possible-word constraint in the segmentation of continuous speech

We propose that word recognition in continuous speech is subject to constraints on what may constitute a viable word of the language. This Possible-Word Constraint (PWC) reduces activation of candidate words if their recognition would imply word status for adjacent input which could not be a word--for instance, a single consonant. In two word-spotting experiments, listeners found it much harder to detect apple, for example, in fapple (where [f] alone would be an impossible word), than in vuffapple (where vuff could be a word of English). We demonstrate that the PWC can readily be implemented in a competition-based model of continuous speech recognition, as a constraint on the process of competition between candidate words; where a stretch of speech between a candidate word and a (known or likely) word boundary is not a possible word, activation of the candidate word is reduced. This implementation accurately simulates both the present results and data from a range of earlier studies of speech segmentation.

Ho endonuclease cleaves MAT DNA in vitro by an inefficient stoichiometric reaction mechanism

Mating type switching in Saccharomyces cerevisiae initiates when Ho endonuclease makes a double-stranded DNA break at the yeast MAT locus. In this report, we characterize the fundamental biochemical properties of Ho. Using an assay that monitors cleavage of a MAT plasmid, we define an optimal in vitro reaction, showing in particular that the enzyme has a stringent requirement for zinc ions. This suggests that zinc finger motifs present in Ho are important for cleavage. The most unexpected feature of Ho, however, is its extreme inefficiency. Maximal cleavage occurs when Ho is present at a concentration of 1 molecule/3 base pairs of substrate DNA. Even under these conditions, complete digestion requires >2 h. This inefficiency results from two characteristics of Ho. First, Ho recycles slowly from cleaved product to new substrate, in part because the enzyme has an affinity for one end of its double strand break product. Second, high levels of cleavage in the in vitro reaction correlate with the appearance of large protein-DNA aggregates. At optimal Ho concentrations, these latter aggregates, referred to as "florettes," have an ordered structure consisting of a densely staining central region and loops of radiating DNA. These unusual properties may indicate that Ho plays a role in other aspects of mating type switching subsequent to double strand break formation.

Progression into the first meiotic division is sensitive to histone H2A-H2B dimer concentration in Saccharomyces cerevisiae

The yeast Saccharomyces cerevisiae contains two genes for histone H2A and two for histone H2B located in two divergently transcribed gene pairs: HTA1-HTB1 and HTA2-HTB2. Diploid strains lacking HTA1-HTB1 (hta1-htb1 delta/hta1-htb1 delta, HTA2-HTB2/HTA2-HTB2) grow vegetatively, but will not sporulate. This sporulation phenotype results from a partial depletion of H2A-H2B dimers. Since the expression patterns of HTA1-HTB1 and HTA2-HTB2 are similar in mitosis and meiosis, the sporulation pathway is therefore more sensitive than the mitotic cycle to depletion of H2A-H2B dimers. After completing premeiotic DNA replication, commitment to meiotic recombination, and chiasma resolution, the hta1-htb1 delta/hta1-htb1 delta, HTA2-HTB2/HTA2-HTB2 mutant arrests before the first meiotic division. The arrest is not due to any obvious disruptions in spindle pole bodies or microtubules. The meiotic block is not bypassed in backgrounds homozygous for spo13, rad50 delta, or rad9 delta mutations, but is bypassed in the presence of hydroxyurea, a drug known to inhibit DNA chain elongation. We hypothesize that the deposition of H2A-H2B dimers in the mutant is unable to keep pace with the replication fork, thereby leading to a disruption in chromosome structure that interferes with the meiotic divisions.

Identification of a protein that binds to the Ho endonuclease recognition sequence at the yeast mating type locus

Mating type switching in Saccharomyces cerevisiae initiates when Ho endonuclease makes a site-specific double-stranded break at MAT, the yeast mating type locus. To identify other proteins involved in this process, we examined whether extracts prepared from ho- mutants contain additional factors that bind near the recognition sequence for Ho. Using an electrophoretic mobility shift assay, we isolated a chromatographic fraction that contains an activity, named YZbp, which binds to two sequences flanking the recognition sequence at MATalpha and to one sequence overlapping it at MATa. MAT plasmids carrying mutations in the YZbp recognition sequence are cleaved by purified Ho at wild-type efficiencies in an in vitro assay. These same plasmids, however, are not cleaved by Ho inside cells, demonstrating that YZbp acts as a positive activator of in vivo cleavage. YZbp is present in all cell types, even those not undergoing mating type switching, suggesting that it has additional cellular functions.

The mouse Smcx gene exhibits developmental and tissue specific variation in degree of escape from X inactivation

The Smcx gene is the first known example of a non-pseudoautosomal X-linked gene in mouse that normally escapes X chromosome inactivation. We have analysed the kinetics of escape at different stages of development, and in adult tissues. Our results demonstrate that Smcx exhibits partial escape from X inactivation in embryos, in extraembryonic lineages where paternally imprinted X inactivation occurs and also in adult tissues. The degree of escape in different tissues is highly variable, the level of transcript from the inactive X allele representing between 20% and 70% of the active X allele. Partial escape is also seen in clones derived from haematopoietic stem cells, suggesting that partial repression of the inactive X allele is at the level of individual cells. This contrasts with classical position effect variegation (PEV), where a given gene is either active or silent in a given cell and its clonal derivatives. We discuss the implications of these results with respect to mechanisms of X inactivation and escape.

Speeded detection of vowels: a cross-linguistic study

In four experiments, listeners' response times to detect vowel targets in spoken input were measured. The first three experiments were conducted in English. In two, one using real words and the other, nonwords, detection accuracy was low, targets in initial syllables were detected more slowly than targets in final syllables, and both response time and missed-response rate were inversely correlated with vowel duration. In a third experiment, the speech context for some subjects included all English vowels, while for others, only five relatively distinct vowels occurred. This manipulation had essentially no effect, and the same response pattern was again observed. A fourth experiment, conducted in Spanish, replicated the results in the first three experiments, except that miss rate was here unrelated to vowel duration. We propose that listeners' responses to vowel targets in naturally spoken input are effectively cautious, reflecting realistic appreciation of vowel variability in natural context.

Delayed bilateral spinal anaesthesia following interscalene brachial plexus block

PURPOSE

To present a case of delayed neuraxial blockade after interscalene brachial plexus block.

CLINICAL FEATURES

A 65-yr-old lady presenting for radial head excision underwent a right interscalene block using bupivacaine and lidocaine. She experienced excellent anaesthesia and had stable vital signs for the duration of surgery. However, after 65 min, she developed signs of bilateral neuraxial block, progressing over the following hour to involve the cervical to lumbar dermatomes, with sparing of the phrenic nerves. The patient remained alert and communicative throughout with haemodynamic stability. Two days following the block, the patient experienced severe frontal and occipital pain, typical of a post dural puncture headache, which responded to fluids and recumbency.

CONCLUSION

This example of delayed central neural blockade complicating interscalene block is presented in contrast to other reports, which have usually occurred promptly after injection, accompanied by complete sensory and motor block requiring cardio-respiratory support. The presumed mechanism of the delayed onset of bilateral neuraxial spread was a dural cuff puncture with slow CSF spread from a plexus sheath "depot" of local anaesthetic.

A comparison of the properties of Sox-3 with Sry and two related genes, Sox-1 and Sox-2

The Sox gene family consists of a large number of embryonically expressed genes related via the possession of a 79-amino-acid DNA-binding domain known as the HMG box. Partial clones for the first three Sox genes (al-a3) were isolated by homology to the HMG box of the testis-determining gene Sry and are now termed Sox-1, Sox-2 and Sox-3, Sox-3 is highly conserved amongst mammalian species and is located on the X chromosome. This has led to the proposal that Sry evolved from Sox-3. We present the cloning and sequencing of Sox-1, Sox-2 and Sox-3 from the mouse and show that Sox-3 is most closely relate to Sry. We also confirm that mouse Sox-3 is located on the X chromosome between Hprt and Dmd. Analysis of the distribution of Sox-3 RNA shows that its main site of expression is in the developing central nervous system, suggesting a role for Sox-3 in neural development. Moreover, we demonstrate that Sox-3, as well as Sox-1 and Sox-2, are expressed in the urogenital ridge and that their protein products are able to bind the same DNA sequence motif as Sry in vitro, but with different affinities. These observations prompt discussion of an evolutionary link between the genes and support the model that Sry has evolved from Sox-3. However our findings imply that if this is true, then Sry has undergone concomitant changes resulting in loss of CNS expression and altered DNA-binding properties.

Competition and segmentation in spoken-word recognition

Spoken utterances contain few reliable cues to word boundaries, but listeners nonetheless experience little difficulty identifying words in continuous speech. The authors present data and simulations that suggest that this ability is best accounted for by a model of spoken-word recognition combining competition between alternative lexical candidates, and sensitivity to prosodic structure. In a word-spotting experiment, stress pattern effects emerged most clearly when there were many competing lexical candidates for part of the input. Thus, competition between simultaneously active word candidates can modulate the size of prosodic effects, which suggests that spoken-word recognition must be sensitive both to prosodic structure and to the effects of competition. A version of the Shortlist model (D. G. Norris, 1994b) incorporating the Metrical Segmentation Strategy (A. Cutler & D. Norris, 1988) accurately simulates the results using a lexicon of more than 25,000 words.

Systemic therapy of cutaneous T-cell lymphomas (mycosis fungoides and the Sézary syndrome)

OBJECTIVE

To review recent studies of systemic therapy for mycosis fungoides and the Sézary syndrome (cutaneous T-cell lymphomas).

DATA SOURCES

English-language articles indexed in MEDLINE from 1988 through 1994.

STUDY SELECTION

All therapeutic studies were selected.

DATA EXTRACTION

The data were abstracted without judgments on response criteria or patient numbers. Data quality and validity were assessed by independent author reviews.

DATA SYNTHESIS

No systemic therapy cures patients with cutaneous T-cell lymphomas. Single and combined chemotherapeutic agents produce high response rates. Whether any of these is preferred is not established. A randomized trial comparing combination chemotherapy plus radiation therapy with topical therapy showed no survival benefit for the combination. Several adenosine analogs and retinoids were active, but their optimal use is uncertain. Interferons are as active as chemotherapeutic agents and may be less toxic. Interferon combined with psoralen plus ultraviolet A light therapy produces high complete response rates and long-lasting remissions. Combinations with other systemic therapies do not increase response rates. Photopheresis therapy should be regarded as experimental. Promising preliminary results were seen with interleukin-2 fusion toxins and several antibody conjugates.

CONCLUSIONS

Systemic therapy should be considered effective and palliative. The principles of treating all low-grade lymphomas can be applied. Randomized trials are needed to evaluate new agents (such as a comparison of psoralen plus ultraviolet light with or without interferon), and large phase II trials are needed for new agents such as photopheresis, interleukin-2 fusion toxin, temozolomide, and others.

Use of 'split' plateletpheresis products for alloimmunized patients

Single donor platelets obtained using the COBE Spectra were split into two halves and administered to alloimmunized patients with leukemia at two different points in time. The mean platelet yield was 6.83 x 10(11) (n = 63) with 56% of collections having yields of > 6.0 x 10(11) (i.e. twice the current AABB recommendation for an apheresis platelet transfusion). In 58 instances, the two halves were administered to the same patient 24-96 h apart. The differences in the correct increments of the split transfusions administered 24-48 h apart were not statistically significant, although there were decreased increments after 72 and 96 h of storage. In 5 instances when the CCI for first transfusion was unacceptably low, the second half was successfully transfused to another patient. This study proves it is feasible to split apheresis platelets into two transfusions, and discusses approaches to optimally use this strategy for the transfusion support of alloimmunized patients.