Breast tumor cell lines from pleural effusions

During 1973, 4 new epithelial tumor cell lines were isolated from pleural effusions from breast cancer patients. We describe 3 of these lines: MDA-MB-134, with a mean chromosome number of 43; MDA-MB-175, with a mean chromosome number of 49; and MDA-MB-231, with a mean chromosome number between 65 and 69. We isolated the same cell type from 4 of 10 effusions from MDA-MB-134 and from 6 of 8 effusions from MDA-MB-175. We found that pleural effusions as a source of breast tumor cells to be cultured and studied in vitro have the following advantages: 1) large amounts of material and the possibility of obtaining sequential samples from the same patient; 2) high viability of tumor cells; 3) scarcity or absence of fibroblasts; and 4) the possibility of separating the tumor cells from other “contaminating” cell types by differences in their speed or degree of attachment to the flask. All lines from different patients differed, as seen grossly and microscopically. All lines from sequential pleural effusions from the same patient were apparently alike. No viruses or mycoplasmas were detected in any line.

Long-term outcome of medical and surgical therapies for gastroesophageal reflux disease: follow-up of a randomized controlled trial

CONTEXT

Severe gastroesophageal reflux disease (GERD) is a lifelong problem that can be complicated by peptic esophageal stricture and adenocarcinoma of the esophagus.

OBJECTIVE

To determine the long-term outcome of medical and surgical therapies for GERD.

DESIGN AND SETTING

Follow-up study conducted from October 1997 through October 1999 of a prospective randomized trial of medical and surgical antireflux treatments in patients with complicated GERD. Mean (median) duration of follow-up was 10.6 years (7.3 years) for medical patients and 9.1 years (6.3 years) for surgical patients.

PARTICIPANTS

Two hundred thirty-nine (97%) of the original 247 study patients were found (79 were confirmed dead). Among the 160 survivors (157 men and 3 women; mean [SD] age, 67 [12] years), 129 (91 in the medical treatment group and 38 in the surgical treatment group) participated in the follow-up.

MAIN OUTCOME MEASURES

Use of antireflux medication, Gastroesophageal Reflux Disease Activity Index (GRACI) scores, grade of esophagitis, frequency of treatment of esophageal stricture, frequency of subsequent antireflux operations, 36-item Short Form health survey (SF-36) scores, satisfaction with antireflux therapy, survival, and incidence of esophageal adenocarcinoma, compared between the medical antireflux therapy group and the fundoplication surgery group. Information on cause of death was obtained from autopsy results, hospital records, and death certificates.

RESULTS

Eighty-three (92%) of 90 medical patients and 23 (62%) of 37 surgical patients reported that they used antireflux medications regularly (P<.001). During a 1-week period after discontinuation of medication, mean (SD) GRACI symptom scores were significantly lower in the surgical treatment group (82.6 [17.5] vs 96.7 [21.4] in the medical treatment group; P =.003). However, no significant differences between the groups were found in grade of esophagitis, frequency of treatment of esophageal stricture and subsequent antireflux operations, SF-36 standardized physical and mental component scale scores, and overall satisfaction with antireflux therapy. Survival during a period of 140 months was decreased significantly in the surgical vs the medical treatment group (relative risk of death in the medical group, 1.57; 95% confidence interval, 1.01-2.46; P =.047), largely because of excess deaths from heart disease. Patients with Barrett esophagus at baseline developed esophageal adenocarcinomas at an annual rate of 0.4%, whereas these cancers developed in patients without Barrett esophagus at an annual rate of only 0.07%. There was no significant difference between groups in incidence of esophageal cancer.

CONCLUSION

This study suggests that antireflux surgery should not be advised with the expectation that patients with GERD will no longer need to take antisecretory medications or that the procedure will prevent esophageal cancer among those with GERD and Barrett esophagus.

Holins: the protein clocks of bacteriophage infections

Two proteins, an endolysin and a holin, are essential for host lysis by bacteriophage. Endolysin is the term for muralytic enzymes that degrade the cell wall; endolysins accumulate in the cytosol fully folded during the vegetative cycle. Holins are small membrane proteins that accumulate in the membrane until, at a specific time that is "programmed" into the holin gene, the membrane suddenly becomes permeabilized to the fully folded endolysin. Destruction of the murein and bursting of the cell are immediate sequelae. Holins control the length of the infective cycle for lytic phages and so are subject to intense evolutionary pressure to achieve lysis at an optimal time. Holins are regulated by protein inhibitors of several different kinds. Holins constitute one of the most diverse functional groups, with >100 known or putative holin sequences, which form >30 ortholog groups.

Bacteriophage lysis: mechanism and regulation

Bacteriophage lysis involves at least two fundamentally different strategies. Most phages elaborate at least two proteins, one of which is a murein hydrolase, or lysin, and the other is a membrane protein, which is given the designation holin in this review. The function of the holin is to create a lesion in the cytoplasmic membrane through which the murein hydrolase passes to gain access to the murein layer. This is necessary because phage-encoded lysins never have secretory signal sequences and are thus incapable of unassisted escape from the cytoplasm. The holins, whose prototype is the lambda S protein, share a common organization in terms of the arrangement of charged and hydrophobic residues, and they may all contain at least two transmembrane helical domains. The available evidence suggests that holins oligomerize to form nonspecific holes and that this hole-forming step is the regulated step in phage lysis. The correct scheduling of the lysis event is as much an essential feature of holin function as is the hole formation itself. In the second strategy of lysis, used by the small single-stranded DNA phage phi X174 and the single-stranded RNA phage MS2, no murein hydrolase activity is synthesized. Instead, there is a single species of small membrane protein, unlike the holins in primary structure, which somehow causes disruption of the envelope. These lysis proteins function by activation of cellular autolysins. A host locus is required for the lytic function of the phi X174 lysis gene E.

Crystal structures of two Sm protein complexes and their implications for the assembly of the spliceosomal snRNPs

The U1, U2, U4/U6, and U5 small nuclear ribonucleoprotein particles (snRNPs) involved in pre-mRNA splicing contain seven Sm proteins (B/B', D1, D2, D3, E, F, and G) in common, which assemble around the Sm site present in four of the major spliceosomal small nuclear RNAs (snRNAs). These proteins share a common sequence motif in two segments, Sm1 and Sm2, separated by a short variable linker. Crystal structures of two Sm protein complexes, D3B and D1D2, show that these proteins have a common fold containing an N-terminal helix followed by a strongly bent five-stranded antiparallel beta sheet, and the D1D2 and D3B dimers superpose closely in their core regions, including the dimer interfaces. The crystal structures suggest that the seven Sm proteins could form a closed ring and the snRNAs may be bound in the positively charged central hole.

Occupational exposure to carcinogens in the European Union

OBJECTIVES

To construct a computer assisted information system for the estimation of the numbers of workers exposed to established and suspected human carcinogens in the member states of the European Union (EU).

METHODS

A database called CAREX (carcinogen exposure) was designed to provide selected exposure data and documented estimates of the number of workers exposed to carcinogens by country, carcinogen, and industry. CAREX includes data on agents evaluated by the International Agency for Research on Cancer (IARC) (all agents in groups 1 and 2A as of February 1995, and selected agents in group 2B) and on ionising radiation, displayed across the 55 industrial classes. The 1990-3 occupational exposure was estimated in two phases. Firstly, estimates were generated by the CAREX system on the basis of national labour force data and exposure prevalence estimates from two reference countries (Finland and the United States) which had the most comprehensive data available on exposures to these agents. For selected countries, these estimates were then refined by national experts in view of the perceived exposure patterns in their own countries compared with those of the reference countries.

RESULTS

About 32 million workers (23% of those employed) in the EU were exposed to agents covered by CAREX. At least 22 million workers were exposed to IARC group 1 carcinogens. The exposed workers had altogether 42 million exposures (1.3 mean exposures for each exposed worker). The most common exposures were solar radiation (9.1 million workers exposed at least 75% of working time), environmental tobacco smoke (7.5 million workers exposed at least 75% of working time), crystalline silica (3.2 million exposed), diesel exhaust (3.0 million), radon (2.7 million), and wood dust (2.6 million).

CONCLUSION

These preliminary estimates indicate that in the early 1990s, a substantial proportion of workers in the EU were exposed to carcinogens.

Glycaemic control of Type 1 diabetes in clinical practice early in the 21st century: an international comparison

AIMS

Improving glycaemic control in people with Type 1 diabetes is known to reduce complications. Our aim was to compare glycaemic control among people with Type 1 diabetes using data gathered in regional or national registries.

METHODS

Data were obtained for children and/or adults with Type 1 diabetes from the following countries (or regions): Western Australia, Austria, Denmark, England, Champagne-Ardenne (France), Germany, Epirus, Thessaly and Thessaloniki (Greece), Galway (Ireland), several Italian regions, Latvia, Rotterdam (The Netherlands), Otago (New Zealand), Norway, Northern Ireland, Scotland, Sweden, Volyn (Ukraine), USA and Wales) from population or clinic-based registries. The sample size with available data varied from 355 to 173 880. Proportions with HbA1c < 58 mmol/mol (< 7.5%) and ≥ 75 mmol/mol (≥ 9.0%) were compared by age and sex.

RESULTS

Data were available for 324 501 people. The proportions with HbA1c 58 mmol/mol (< 7.5%) varied from 15.7% to 46.4% among 44 058 people aged < 15 years, from 8.9% to 49.5% among 50 766 people aged 15-24 years and from 20.5% to 53.6% among 229 677 people aged ≥ 25 years. Sex differences in glycaemic control were small. Proportions of people using insulin pumps varied between the 12 sources with data available.

CONCLUSION

These results suggest that there are substantial variations in glycaemic control among people with Type 1 diabetes between the data sources and that there is room for improvement in all populations, especially in young adults.

Rapid and sensitive pollutant detection by induction of heat shock gene-bioluminescence gene fusions

Heat shock gene expression is induced by a variety of environmental stresses, including the presence of many chemicals. To address the utility of this response for pollutant detection, two Escherichia coli heat shock promoters, dnaK and grpE, were fused to the lux genes of Vibrio fischeri. Metals, solvents, crop protection chemicals, and other organic molecules rapidly induced light production from E. coli strains containing these plasmid-borne fusions. Introduction of an outer membrane mutation, tolC, enhanced detection of a hydrophobic molecule, pentachlorophenol. The maximal response to pentachlorophenol in the tolC+ strain was at 38 ppm, while the maximal response in an otherwise isogenic tolC mutant was at 1.2 ppm. Stress responses were observed in both batch and chemostat cultures. It is suggested that biosensors constructed in this manner may have potential for environmental monitoring.

Genome-wide DNA methylation analysis of human brain tissue from schizophrenia patients

Recent studies suggest that genetic and environmental factors do not account for all the schizophrenia risk, and epigenetics also has a role in disease susceptibility. DNA methylation is a heritable epigenetic modification that can regulate gene expression. Genome-wide DNA methylation analysis was performed on post-mortem human brain tissue from 24 patients with schizophrenia and 24 unaffected controls. DNA methylation was assessed at over 485,000 CpG sites using the Illumina Infinium HumanMethylation450 Bead Chip. After adjusting for age and post-mortem interval, 4641 probes corresponding to 2929 unique genes were found to be differentially methylated. Of those genes, 1291 were located in a CpG island and 817 were in a promoter region. These include NOS1, AKT1, DTNBP1, DNMT1, PPP3CC and SOX10, which have previously been associated with schizophrenia. More than 100 of these genes overlap with a previous DNA methylation study of peripheral blood from schizophrenia patients in which 27,000 CpG sites were analysed. Unsupervised clustering analysis of the top 3000 most variable probes revealed two distinct groups with significantly more people with schizophrenia in cluster one compared with controls (P=1.74 × 10(-4)). The first cluster composed of 88% of patients with schizophrenia and only 12% controls, whereas the second cluster composed of 27% of patients with schizophrenia and 73% controls. These results strongly suggest that differential DNA methylation is important in schizophrenia etiology and add support for the use of DNA methylation profiles as a future prognostic indicator of schizophrenia.

Long-term culture and fine specificity of human cytotoxic T-lymphocyte clones reactive with human immunodeficiency virus type 1

The definition of human immunodeficiency virus type 1 (HIV-1) immunogenic epitopes is central to the rational design of AIDS vaccine strategies. In this study, we have generated seven HIV-1 reverse transcriptase-specific cytotoxic T-lymphocyte (CTL) clones from the peripheral blood of two seropositive subjects. Epitopes recognized by these CTL clones were identified by using target cells infected with recombinant HIV-1-vaccinia virus vectors expressing truncated reverse transcriptase proteins and further defined by using target cells incubated with overlapping 25-amino acid synthetic reverse transcriptase peptides. Five different CTL epitopes were identified, and in each case recognition was restricted by class I human leukocyte antigens (HLA). Clones maintained specific cytolytic function in continuous culture for up to 11 months, requiring only periodic restimulation with a CD3-specific monoclonal antibody. These results indicate that HIV-1-specific, major histocompatibility class I-restricted CTL recognize multiple epitopes of a single viral gene product in conjunction with different host HLA antigens. In addition, they demonstrate that human virus-specific CTL can be grown in long-term culture without the need for reexposure to viral antigen.

Eucaryotic RNA polymerase conditional mutant that rapidly ceases mRNA synthesis

We have isolated a yeast conditional mutant which rapidly ceases synthesis of mRNA when subjected to the nonpermissive temperature. This mutant (rpb1-1) was constructed by replacing the wild-type chromosomal copy of the gene encoding the largest subunit of RNA polymerase II with one mutagenized in vitro. The rapid cessation of mRNA synthesis in vivo and the lack of RNA polymerase II activity in crude extracts indicate that the mutant possesses a functionally defective, rather than an assembly-defective, RNA polymerase II. The shutdown in mRNA synthesis in the rpb1-1 mutant has pleiotropic effects on the synthesis of other RNAs and on the heat shock response. This mutant provides direct evidence that the RPB1 protein has a functional role in mRNA synthesis.

Intravascular extraction of problematic or infected permanent pacemaker leads: 1994-1996. U.S. Extraction Database, MED Institute

Of the 400,000-500,000 permanent pacemaker leads implanted worldwide each year, around 10% may eventually fail or become infected, becoming potential candidates for removal. Intravascular techniques for removing problematic or infected leads evolved over a 5-year period (1989-1993). This article analyzes results from January 1994 through April 1996, a period during which techniques were fairly stable. Extraction of 3,540 leads from 2,338 patients was attempted at 226 centers. Indications were: infection (27%), nonfunctional or incompatible leads (25%), Accufix or Encore leads (46%), or other causes (2%). Patients were 64+/-17 years of age (range 5-96); 59% were men, 41% women. Leads were implanted 47+/-41 months (maximum 26 years), in the atrium (53%), ventricle (46%), or SVC (1%). Extraction was attempted via the implant vein using locking stylets and dilator sheaths, and/or transfemorally using snares, retrieval baskets, and sheaths. Complete removal was achieved for 93% of leads, partial for 5%, and 2% were not removed. Risk of incomplete or failed extraction increased with implant duration (P<0.0001), less experienced physicians (P<0.0001), ventricular leads (P<0.005), noninfected patients (P<0.0005), and younger patients (P<0.0001). Major complications were reported for 1.4% of patients (<1% at centers with >300 cases), minor for 1.7%. Risk of complications increased with number of leads removed (P<0.005) and with less experienced physicians (P<0.005); risk of major complications was higher for women (P<0.01). Given physician experience, appropriate precautions, and appropriate patient selection, contemporary lead removal techniques allow success with low complication rates.

Classification of fungal chitin synthases

Comparison of the chitin synthase genes of Saccharomyces cerevisiae CHS1 and CHS2 with the Candida albicans CHS1 gene (UDP-N-acetyl-D-glucosamine:chitin 4-beta-N-acetylglucosaminyltransferase, EC 2.4.1.16) revealed two small regions of complete amino acid sequence conservation that were used to design PCR primers. Fragments homologous to chitin synthase (approximately 600 base pairs) were amplified from the genomic DNA of 14 fungal species. These fragments were sequenced, and their deduced amino acid sequences were aligned. With the exception of S. cerevisiae CHS1, the sequences fell into three distinct classes, which could represent separate functional groups. Within each class phylogenetic analysis was performed. Although not the major purpose of the investigation, this analysis tends to confirm some relationships consistent with current taxonomic groupings.

Tissue distribution of mRNAs encoding the alpha isoforms and beta subunit of rat Na+,K+-ATPase

The tissue distribution of the multiple forms of rat Na+,K+-ATPase was examined at the molecular level with cDNA probes specific for the alpha, alpha (+), alpha III and beta subunit mRNAs. Northern and slot blot analyses demonstrate that these mRNAs are produced in a tissue-specific manner. RNAs encoding the alpha (+) isoform are detected in kidney, brain, heart, adipose, muscle, stomach and lung, whereas alpha III RNA is detected in brain, stomach and lung. Both alpha and beta mRNAs are present in all the tissues studied, although at very different levels. Examination of heart tissue in greater detail demonstrates that the levels of mRNA encoding the alpha subunit are greater in the atria than in the ventricles, while the converse is true for alpha (+).

Antagonism of the effects of the hallucinogen DOM and the purported 5-HT agonist quipazine by 5-HT2 antagonists

Rats trained to discriminate 1.0 mg/kg of 1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane (DOM) from saline in a two-lever operant choice task were administered doses of mescaline, LSD, 5-methoxy-N,N-dimethyltryptamine (5-OMe DMT), quipazine, TFMPP and RU-24969. The DOM-stimulus generalized to the three hallucinogenic agents and to quipazine, but not to the purported serotonin agonists TFMPP or RU-24969. Pretreatment of the animals with the 5-HT2 antagonists ketanserin and pirenperone antagonized the effect produced by DOM. Pirenperone also blocked DOM-stimulus generalization to mescaline, LSD, 5-OMe DMT and quipazine. The results of this study suggest that the discriminative stimulus effects of DOM, the three hallucinogenic agents to which DOM-stimulus generalization occurred, and quipazine, may involve those sub-populations of serotonin receptors that are labeled by tritiated ketanserin (i.e. 5-HT2 sites).

The results of in situ prosthetic replacement for infected aortic grafts

BACKGROUND

Treatment of aortic graft infection with graft excision and axillofemoral bypass may carry an increased risk of limb loss, aortic stump blowout, and pelvic ischemia. A review of patients with aortic graft infection treated with in situ prosthetic graft replacement was undertaken to determine if mortality, limb loss, and reinfection rates were improved with this technique.

METHODS

The clinical data of 25 patients, 19 males and 6 females, with a mean age of 68 years (range 35 to 83), with aortic graft infection, treated between January 1, 1989, and December 31, 1998, by in situ prosthetic graft replacement were reviewed. Follow-up was complete in the 23 surviving patients and averaged 36 months (range 4 to 103).

RESULTS

Twenty aortofemoral, 3 aortoiliac, and 2 straight aortic graft infections were treated with excision and in situ replacement with standard polyester grafts in 16 patients (64%), or with rifampin-soaked collagen or gelatin-impregnated polyester grafts in 9 patients (36%). Fifteen patients (60%) had aortic graft enteric fistulas, 8 patients (32%) had abscesses or draining sinuses, and 2 patients (8%) had bacterial biofilm infections. Thirty-day mortality was 8% (2 of 25). There were no early graft occlusions or amputations. There was one late graft occlusion. There were no late amputations. The reinfection rate was 22% (5 grafts). All reinfections occurred in patients operated upon for occlusive disease. Only one reinfection occurred in the rifampin-soaked graft group (11% versus 29%, P = NS). Reinfection tended to be lower in patients with aortoenteric fistulas and without abscess. Autogenous tissue coverage provided statistically significant protection against reinfection. There were no late deaths related to in situ graft infection.

CONCLUSIONS

Patients treated with in situ graft replacement had an 8% mortality and 100% limb salvage rate. Reinfection rates were similar to those of extra-anatomic bypass, but a trend of lower reinfection rates with rifampin-impregnated grafts was apparent. Patients with aortoenteric fistula and without abscess appear to be well treated by the technique of in situ prosthetic grafting and autogenous tissue coverage.

Holins kill without warning

Holins comprise the most diverse functional group of proteins known. They are small bacteriophage-encoded proteins that accumulate during the period of late-protein synthesis after infection and cause lysis of the host cell at a precise genetically programmed time. It is unknown how holins achieve temporal precision, but a conserved feature of their function is that energy poisons subvert the normal scheduling mechanism and instantly trigger membrane disruption. On this basis, timing has been proposed to involve a progressive decrease in the energized state of the membrane until a critical triggering level is reached. Here, we report that membrane integrity is not compromised after the induction of holin synthesis until seconds before lysis. The proton motive force was monitored by the rotation of individual cells tethered by a single flagellum. The results suggest an alternative explanation for the lysis "clock," in which holin concentrations build to a critical level that leads to formation of an oligomeric complex that disrupts the membrane.

Prostaglandin receptor EP(4) mediates the bone anabolic effects of PGE(2)

Prostaglandin (PG) E(2) is a potent inducer of cortical and trabecular bone formation in humans and animals. Although the bone anabolic action of PGE(2) is well documented, the cellular and molecular mechanisms that mediate this effect remain unclear. This study was undertaken to examine the effect of pharmacological inactivation of the prostanoid receptor EP(4), one of the PGE(2) receptors, on PGE(2)-induced bone formation in vivo. We first determined the ability of EP(4)A, an EP(4)-selective ligand, to act as an antagonist. PGE(2) increases intracellular cAMP and suppresses apoptosis in the RP-1 periosteal cell line. Both effects were reversed by EP(4)A, suggesting that EP(4)A acts as an EP(4) antagonist in the cells at concentrations consistent with its in vitro binding to EP(4). We then examined the effect of EP(4) on bone formation induced by PGE(2) in young rats. Five- to 6-week-old rats were treated with PGE(2) (6 mg/kg/day) in the presence or absence of EP(4)A (10 mg/kg/day) for 12 days. We found that treatment with EP(4)A suppresses the increase in trabecular bone volume induced by PGE(2). This effect is accompanied by a suppression of bone formation indices: serum osteocalcin, extent of labeled surface, and extent of trabecular number, suggesting that the reduction in bone volume is due most likely to decreased bone formation. The pharmacological evidence presented here provides strong support for the hypothesis that the bone anabolic effect of PGE(2) in rats is mediated by the EP(4) receptor.

Prospective randomized evaluation of adjuvant chemotherapy in adults with soft tissue sarcomas of the extremities

Sixty-five patients with high-grade soft tissue sarcomas of the extremities were treated in a prospective randomized trial evaluating the efficacy of adjuvant chemotherapy with doxorubicin, cyclophosphamide, and high-dose methotrexate. Local therapy was administered using either amputation or wide local resection plus radiation therapy and the chemotherapy was begun in the immediate postoperative period. Actuarial analysis with median follow-up of 653 days revealed an advantage in continuous disease-free and overall survival in the patient group receiving chemotherapy (P = 0.0008 and P = 0.04, respectively, one-sided Mantel-Haenszel test). The continuous disease-free survival at three years is 92% in the chemotherapy group compared to 60% in the no chemotherapy group. Overall survival is 95% and 74% in these two patient groups. Fifty-eight percent of patients had limb-sparing surgery plus radiation therapy and 42% underwent amputation. In both treatment subgroups analyzed separately, chemotherapy resulted in an improvement in disease-free survival compared to randomized controls not receiving chemotherapy (P = 0.006 and P = 0.04 for groups receiving amputation and limb sparing, respectively). There were no local failures in the patients receiving chemotherapy and two local failures in the no chemotherapy group. The results of this trial confirm the historically controlled pilot trial performed in 26 patients between 1975 and 1977. A current update of the patients in the pilot trial, with a minimum four-year follow-up, reveals an improvement in disease-free and overall survival due to chemotherapy (P less than 0.002). Analysis of the previous pilot trial indicates that only few recurrences are seen beyond three years. Thus, it appears that adjuvant chemotherapy should be a part of the treatment adult patients with soft tissue sarcomas of the extremities.

The D(2) dopamine receptor A(1) allele and opioid dependence: association with heroin use and response to methadone treatment

A total of 95 Caucasian opioid-dependent patients were followed over a one-year period in an outpatient methadone treatment program. The frequency of the TaqI A(1) allele of the D(2) dopamine receptor (DRD2) gene was 19.0% in these patients compared with 4.6% in controls free of past and current alcohol and other drug abuse and free of family history of alcohol and other drug abuse (p = 0.009). Twenty-two of these patients dropped out of the methadone program (Group A), 54 had a successful treatment (Group B), and 19 had a poor treatment (Group C) outcome. The frequency of the A(1) allele was highest in Group C (42.1%), followed by Group A (22.7%) and was lowest in Group B (9.3%). The more than fourfold higher frequency of the A(1) allele in the poor treatment outcome group compared with the successful treatment outcome group was significant (p = 0.00002). Moreover, the average use of heroin (grams/day) during the year prior to study entry was more than twice as great in patients with the A(1)(+) allele (A(1)/A(1) or A(1)/A(2) genotype) than those with the A(1)(-) allele (A(2)/A(2) genotype) (A(1)(+) allele = 0.55 +/- 0. 10, A(1)(-) allele = 0.25 +/- 0.05; p = 0.003). The results indicate that DRD2 variants are predictors of heroin use and subsequent methadone treatment outcome and suggest a pharmacogenetic approach to the treatment of opioid dependence.

Holins: form and function in bacteriophage lysis

During the lytic cycle of most bacteriophages, a phage-encoded peptidoglycan-degrading activity is elaborated. At least four entirely distinct types of enzymes fulfill this role and are given the generic name 'endolysin'. Endolysins characterized to date are synthesized without a signal sequence and thus accumulate fully folded and active in the cytosol during the vegetative phase. Small membrane proteins are required in order for endolysins to gain access to the peptidoglycan. Because the available data suggest that the membrane lesion formed by these proteins is stable and non-specific, these proteins have been given the designation 'holins' ('hole'-formers). Analysis of the primary sequence suggests a simple membrane topology with two or more membrane-spanning helical domains and a highly charged, hydrophilic C-terminus. Comparison of the sequences of holins from phages of Gram-negative hosts suggests there are at least two major holin groups. Putative holin genes have also been found in bacteriophages of Gram-positive bacteria. Altogether, in phages of Eubacteria, 11 or more unrelated gene families which share the functional and structural characteristics of holins have been identified. Genetic and physiological analysis suggest that holins are primarily regulated at the level of function. Holin function is modulated in some cases by a second protein encoded by the holin gene. The primary regulation of holin function, however, appears to be intrinsic to the holin structure itself, since a missense allele of the S holin gene of phage lambda has been found which abolishes the normal delay that allows the vegetative phase to generate a useful number of progeny.

Normative data stratified by age and education for the Neuropsychological Screening Battery for Hispanics (NeSBHIS): Initial report

Neuropsychological assessment of monolingual Spanish-speaking people in the United States is both a common practice and an ethical dilemma. Lack of appropriate tests, the absence of norms, use of interpreters, and the multiplicity of in-house translations of commonly used measures add to the problem of accurate assessment. This paper helps address the lack of appropriate measures for the neuropsychological assessment of Latinos in the United States by providing a standardization of the Neuropsychological Screening Battery for Hispanics (NeSBHIS). Normative data on a sample of 300 Hispanic subjects stratified by gender, age, and education are provided. Current results reveal that not one measure of cognitive functioning is free from education effects. Both nonverbal measures and psychomotor speed measures were highly related to education. Age effects were noted on measures of psychomotor speed, visuospatial reasoning, and visuoconstructive skills. Gender effects were found on measures of psychomotor speed and language, with males achieving higher scores than females. The limitations of the current findings are considered. Further research for the validation of the NeSBHIS with clinical populations, as well as further normative data collection at the national and international levels, is needed.

Psychotic symptom and cannabis relapse in recent-onset psychosis. Prospective study

BACKGROUND

Cannabis use appears to exacerbate psychotic symptoms and increase risk of psychotic relapse. However, the relative contribution of cannabis use compared with other risk factors is unclear. The influence of psychotic symptoms on cannabis use has received little attention.

AIMS

To examine the influence of cannabis use on psychotic symptom relapse and the influence of psychotic symptom severity on relapse in cannabis use in the 6 months following hospital admission.

METHOD

At baseline, 84 participants with recent-onset psychosis were assessed and 81 were followed up weekly for 6 months, using telephone and face-to-face interviews.

RESULTS

A higher frequency of cannabis use was predictive of psychotic relapse, after controlling for medication adherence, other substance use and duration of untreated psychosis. An increase in psychotic symptoms was predictive of relapse to cannabis use, and medication adherence reduced cannabis relapse risk.

CONCLUSIONS

The relationship between cannabis use and psychosis may be bidirectional, highlighting the need for early intervention programmes to target cannabis use and psychotic symptom severity in this population.

Polypeptide-chain-elongation rate in Escherichia coli B/r as a function of growth rate

By evaluating the kinetics of radioactive labelling of nascent and finished polypeptides, the peptide-chain elongation rate for Escherichia coli B/r at three different growth rates (mu) was determined to be 17 amino acids/s for the fast-growing cells (mu equals 1.3 and 2.0 doublings/h) and 12 amino acids/s for slow-growing cells (mu equals 0.67 doublings/h). The results agree with the growth-rate-dependence of the rate of peptide-chain elongation found for the translation of newly induced beta-galactosidase messenger in this strain and under these conditions of growth [Dalbow & Young (1975) Biochem. J. 150, 13-20]. Together with the previously observed ribosome efficiency at these growth rates [Dennis & Bremer (1974) J. Mol. Biol. 84, 407-422] the results indicate that the fraction of ribosomes engaged in protein synthesis is about 0.8 at all three growth rates.

Prognostic indicators for gastrointestinal stromal tumours: a clinicopathological and immunohistochemical study of 108 resected cases of the stomach

AIMS

Whether immunohistochemical markers increase accuracy in predicting prognosis for gastrointestinal stromal tumours (GISTs) remains uncertain. However, past studies have used only small, heterogeneous patient groups. Our aim was to test previously studied and more novel morphological features as well as four immunohistochemical markers as prognostic indicators amongst a large cohort of surgically resected, gastric GISTs.

METHODS AND RESULTS

Tissues from 127 gastric mesenchymal tumours were collected retrospectively and subjected to repeat histological assessment and immunophenotyping. Further immunohistochemistry was performed for Ki67, p53, Bcl-2 and cyclin D1. Complete follow-up data were collected for 108 patients with immunophenotyped diagnoses of GIST (i.e. c-kit+ tumours). At the census point, 52 patients were alive, 24 had died from their GISTs and the remainder of other causes. Univariate analysis showed the following predicted for shorter disease-specific survival: size > or =50 mm; necrosis, no intratumoral lymphocytes; mitotic count > or =5/50 high power fields; Ki67 labelling index > or =5%; p53 immunopositivity. Of these variables, multivariate analyses showed only mitotic count and, to a lesser extent, Ki67 labelling to be independent prognostic indicators.

CONCLUSIONS

Mitotic count remains the best predictor of outcome following surgical resection of gastric GISTs. Ki67 immunohistochemistry does not provide better prognostication and p53, Bcl-2 and cyclin D1 immunohistochemistry provide no additional prognostication.