The relationship between plasma cholesterol concentration and minor psychiatric disturbance in the Department of the Environment Study

We examined the hypothesis that low plasma cholesterol concentration was associated with minor psychiatric disturbance in a cross-sectional study of 410 male and 138 female civil servants. Psychiatric disturbance was measured using the 30-item General Health Questionnaire (GHQ). Mean GHQ score did not vary significantly with quartile of total cholesterol concentration. After adjustment for confounding variables a significant trend of increasing mean GHQ with increasing cholesterol concentration emerged. In a logistic regression analysis subjects in the highest quartile of cholesterol concentration had an adjusted odds ratio for being a "psychiatric case" of 2.0 (95% confidence interval, 1.1-2.5) compared with those in the lowest quartile. This relationship reversed when using a higher cutoff point to define more severe cases, although the trend was not statistically significant.

Chemical properties which control selectivity and efficacy of aromatic N-oxide bioreductive drugs

Pulse radiolysis was used to generate radicals from one electron reduction of 1,2,4-benzotriazine-1,4-dioxides (derivatives of tirapazamine), and of imidazo [1,2-a]quinoxaline-4-oxides (analogues of RB90740), which have selective toxicity towards hypoxic cells. Radicals from the mono N-oxides (from the latter compounds) react with oxygen approximately 10-40 times faster than does the tirapazamine radical. Radicals from the tirapazamine analogues studied react with oxygen up to approximately 10 times slower than tirapazamine radicals. The quinoxaline N-oxide radicals are involved in prototropic equilibria with pK(a) values (5.5 to 7.4) spanning that reported for tirapazamine (6.0). Generation of radicals radiolytically in the presence of H donors (formate, 2-propanol, deoxyribose) indicate a chain reaction ascribed to H abstraction by the drug radical. The protonated drug radical is much more reactive than the radical anion (H abstraction rate constant approximately equal to 10(2) - 10(3) dm3 mol-1 s-1). Chain termination is ascribed to drug radical-radical reactions, i.e. radical stability in anoxia, with rate constants 2k approximately equal to 1 x 10(7) to 2 x 10(8) dm3 mol-1 s-1 at pH approximately 7.4. Estimates of the reduction potentials of the drug-radical couples in water at pH 7 for two of the mono-N-oxides were in the range-0.7 to 0.8 V vs NHE at pH 7.

The molecular response of mammalian cells to hypoxia and the potential for exploitation in cancer therapy

In this review, reports of the increased expression of selected genes in response to hypoxia have been summarised. The best studied mammalian hypoxia response systems are those of the erythropoietin (Epo) and the vascular endothelial growth factor (VEGF) genes, which will be described in some detail. Other genes discussed here include those encoding growth factors, cytokines, transcription factors, metabolic enzymes and DNA repair enzymes. Short DNA sequences (hypoxia response elements) governing the increased gene expression in response to hypoxia have been discovered in the vicinity of most of these genes. The review will end by analysing the possibility of exploiting tumour hypoxia via the use of hypoxia response elements for gene therapy of cancer.

Commentary: strength and importance of the relation of dietary salt to blood pressure. Intersalt Steering and Editorial Committee

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Screening for colorectal cancer by once only sigmoidoscopy: a feasibility study in Turin, Italy

OBJECTIVES

To assess the impact on compliance of three invitation methods, as well as the acceptability and efficacy of two bowel preparation regimens, for endoscopic screening in the general population.

METHODS

1170 subjects (men and women aged 55 to 59, in the rosters of a sample of general practitioners (GPs) in Turin), were randomly allocated to one of three invitation groups (A: personal letter, signed by GP, with a pre-fixed appointment; B: same as for A + letter supporting the study by a well known scientist; C: letter signed by the study coordinator, NS) and two preparation regimens (i: one enema, self administered at home two hours before the test; ii: two enemas, administered the night before and two hours before the test). A postal reminder was mailed to non-attenders. A sample of non-responders was contacted for a telephone interview by a trained nurse. Written consent was obtained from all subjects undergoing the test.

RESULTS

A total of 278 subjects attended for sigmoidoscopic screening. An invitation from the GP alone produced the highest response rate (compliance: A = 29.3%; B = 24.9%; C = 26.8%). A single enema was as effective as two enemas in achieving satisfactory preparation for the test: the proportion of subjects invited to repeat the test was 8.1% in the single enema group, and 9.6% in the group receiving two enemas.

CONCLUSIONS

Compliance with this screening procedure tends to be low. One enema, self administered two hours before sigmoidoscopy, can ensure a satisfactory bowel preparation.

Human cytomegalovirus immediate-early 2 (IE2) protein can transactivate the human hsp70 promoter by alleviation of Dr1-mediated repression

The immediate-early 1 and 2 (IE1 and IE2, respectively) proteins of human cytomegalovirus are known transcription factors, which regulate the expression of viral and cellular genes. Transcriptional activation by IE2 is dependent on the presence of a TATA motif in target promoters, and IE2 can interact directly with the TATA-binding protein (TBP) component of TFIID. TBP is known to be the target for transcriptional repression by the cellular Dr1 protein, and this factor has been shown to repress expression from the hsp70 promoter in vivo. Since this promoter is up-regulated by IE2, we asked whether the effects of Dr1 can be overcome by IE2. We report here that IE2 can overcome Dr1-mediated repression of the hsp70 promoter in vivo and that IE2 can interact with Dr1 in vivo and in vitro. We also demonstrate a previously unreported activity of Dr1, inhibition of DNA binding by TBP, and show that IE2 is able to overcome this inhibition in vitro, suggesting a mechanism for the TATA dependency of IE2-mediated trans activation.

The biological, social and clinical bases of drug addiction: commentary and debate

This article summarizes the main discussions at a meeting on the biological, social and clinical bases of drug addiction focused on contemporary topics in drug dependence. Four main domains are surveyed, reflecting the structure of the meeting: psychological and pharmacological factors; neurobiological substrates; risk factors (including a consideration of vulnerability from an environmental and genetic perspective); and clinical treatment. Among the topics discussed were tolerance, sensitization, withdrawal, craving and relapse; mechanisms of reinforcing actions of drugs at the behavioural, cognitive and neural levels; the role of subjective factors in drug dependence; approaches to the behavioural and molecular genetics of drug dependence; the use of functional neuroimaging; pharmaceutical and psychosocial strategies for treatment; epidemiological and sociological aspects of drug dependence. The survey takes into account the considerable disagreements and controversies arising from the discussions, but also reaches a degree of consensus in certain areas.

EagI and NotI linking clones from human chromosomes 11 and Xp

EagI and NotI linking libraries were prepared in the lambda vector, EMBL5, from the mouse-human somatic cell hybrid 1W1LA4.9, which contains human chromosomes 11 and Xp as the only human component. Individual clones containing human DNA were isolated by their ability to hybridise with total human DNA and digested with SalI and EcoRI to identify the human insert size and single-copy fragments. The mean (+/- SD) insert sizes of the EagI and NotI clones were 18.3 +/- 3.2 kb and 16.6 +/- 3.6 kb, respectively. Regional localisation of 66 clones (52 EagI, 14 NotI) was achieved using a panel of 20 somatic cell hybrids that contained different overlapping deletions of chromosomes 11 or Xp. Thirty-nine clones (36 EagI, 3 NotI) were localised to chromosome 11; 17 of these were clustered in 11q13 and another nine were clustered in 11q14-q23.1. Twenty-seven clones (16 EagI, 11 NotI) were localised to Xp and 10 of these were clustered in Xp11. The 66 clones were assessed for seven different microsatellite repetitive sequences; restriction fragment length polymorphisms for five clones from 11q13 were also identified. These EagI and NotI clones, which supplement those previously mapped to chromosome 11 and Xp, should facilitate the generation of more detailed maps and the identification of genes that are associated with CpG-rich islands.

Transcription factors in disease

Mutations affecting several predominantly tissue-specific transcriptional regulators have recently been associated with disease phenotypes. Although the mutational spectrum is variable, many of the reported cases involve clear loss-of-function mutations-such as Waardenburg syndrome type 1, aniridia and Rubinstein-Taybi syndrome-suggesting that the genetic mechanism involved in disease is haplo-insufficiency. The high degree of dosage sensitivity often appears to affect only a subset of the tissues that express the gene. Position effects with cytogenetic rearrangements well outside the coding region have been implicated for four of the genes discussed: POU3F4, SOX9, PAX6, and GL13.

Intersalt revisited: further analyses of 24 hour sodium excretion and blood pressure within and across populations. Intersalt Cooperative Research Group

OBJECTIVES

To assess further the relation in Intersalt of 24 hour urinary sodium to blood pressure of individuals and populations, and the difference in blood pressure from young adulthood into middle age.

DESIGN

Standardised cross sectional study within and across populations.

SETTING

52 population samples in 32 countries.

SUBJECTS

10,074 men and women aged 20-59.

MAIN OUTCOME MEASURES

Association of sodium and blood pressure from within population and cross population multiple linear regression analyses with multivariate correction for regression dilution bias. Relation of sample median daily urinary sodium excretion to difference in blood pressure with age.

RESULTS

In within population analyses (n = 10,074), individual 24 hour urinary sodium excretion higher by 100 mmol (for example, 170 v 70 mmol) was associated with systolic/diastolic blood pressure higher on average by 3/0 to 6/3 mm Hg (with and without body mass in analyses). Associations were larger at ages 40-59. In cross population analyses (n = 52), sample median 24 hour sodium excretion higher by 100 mmol was associated with median systolic/diastolic pressure higher on average by 5-7/2-4 mm Hg, and estimated mean difference in systolic/diastolic pressure at age 55 compared with age 25 greater by 10-11/6 mm Hg.

CONCLUSIONS

The strong, positive association of urinary sodium with systolic pressure of individuals concurs with Intersalt cross population findings and results of other studies. Higher urinary sodium is also associated with substantially greater differences in blood pressure in middle age compared with young adulthood. These results support recommendations for reduction of high salt intake in populations for prevention and control of adverse blood pressure levels.

Testing of cerebrospinal compensatory reserve in shunted and non-shunted patients: a guide to interpretation based on an observational study

OBJECTIVE

To design a computerised infusion test to compensate for the disadvantages of Katzman's lumbar infusion method: inadequate accuracy of estimation of the resistance to cerebrospinal fluid outflow and poor predictive value in normal pressure hydrocephalus.

METHODS

Accuracy was improved by intracranial pressure signal processing and model analysis for measurement of cerebrospinal compensatory variable. These include the CSF outflow resistance, brain compliance, pressure-volume index, estimated sagittal sinus pressure, CSF formation rate, and other variables. Infusion may be made into the lumbar space, ventricles, or, when assessing shunt function in vivo, the shunt chamber.

RESULTS AND CONCLUSIONS

The computerised test has been used for five years in a multicentre study in 350 hydrocephalic patients of various ages, aetiologies, and states of cerebrospinal compensation. The principles of using the test to characterise different types of CSF circulatory disorders in patients presenting with ventricular dilatation, including brain atrophy and normal and high pressure hydrocephalus, are presented and illustrated. Previous studies showed a positive correlation between cerebrospinal compensatory variables and the results of shunting, but such a prediction remains difficult in idiopathic normal pressure hydrocephalus, particularly in elderly patients. The technique is helpful in the assessment of shunt malfunction, including posture-related overdrainage, over-drainage related to the nocturnal B wave activity, and proximal or distal shunt obstruction. The appendix presents an introduction of the mathematical modelling of CSF pressure volume-compensation included in computerised infusion test software.

Linkage, association and mutational analysis of the dopamine D3 receptor gene in schizophrenia

This study follows the observation of an association between homozygosity of an Mscl polymorphism in exon 1 and schizophrenia, which gives rise to a glycine to serine substitution and may alter the functional properties of the receptor. Alternatively the polymorphism may not itself be of functional significance but may be in linkage disequilibrium with another genetic variant in the coding or regulatory regions. To examine the second possibility we have screened all six exons of DRD3 by single-stranded conformational polymorphism analysis (SSCP) in 36 cases and 36 controls. Our findings suggest that the gene is highly conserved since we found no other mutations which alter protein structure. However we did detect a 5-bp deletion in the 3' intronic sequence flanking exon 5 which occurred in 7-8% of subjects within both case and control samples. A single bp substitution (g to a) in exon 3, which does not alter an amino acid was found in one affected individual. In addition we carried out a linkage study of 24 families multiply affected with schizophrenia and a non-parametric linkage study of 90 affected sibling pairs. These studies give no support for either major or moderate gene effects on schizophrenia susceptibility. Finally we have extended our association sample and observe a non-significant excess of homozygotes for the Mscl polymorphism in the sample overall (chi 2 = 2.09, 1 d.f., P = 0.15). The excess of homozygotes is specific to males (chi 2 = 4.617, 1 d.f., P = 0.032) and not females (chi 2 = 0.243, 1 d.f., NS). When these data are added to our previous published data a highly significant excess of homozygotes is observed in males (chi 2 = 13.766, 1 d.f., P = 0.00021) but not females (chi 2 = 0.606, 1 d.f., NS). In conclusion the accumulated data suggest strongly that genetic variation at the DRD3 locus increases susceptibility of schizophrenia, at least in males. At present the Mscl polymorphism in exon 1 of the gene remains a candidate for bringing about functional change in the receptor but this has not been formally tested. Other coding region polymorphisms have not been detected but it remains possible that variation within the promoter may alter receptor function.

Significance of intracranial pressure waveform analysis after head injury

The authors have investigated the relationships between the amplitude of the ICP pulse wave, the mean values of ICP and CPP, and the outcome of 56 head injured ventilated patients. The ICP was monitored continuously using a Camino transducer (35 patients) or subdural catheter (21 patients). The mean Glasgow Coma Score was 6 (range 3-13; 5 patients had a GCS > 8 after resuscitation). Patients were grouped according to their Glasgow Outcome Score assessed at 12 months after injury. The amplitude of ICP pulse waveform was assessed using the fundamental harmonic of the pulse waveform (AMP) to avoid distortion caused by different frequency responses of the pressure transducers used in the study. Statistical analysis revealed that in patients with fatal outcome the ICP pulse amplitude increased when the mean ICP increased to 25 mmHg and then began to decrease. The upper breakpoint of the AMP-ICP relationship was not present in patients with good/moderate outcome. The moving correlation coefficient between the fundamental harmonic of ICP pulse wave and the mean ICP (RAP: R-symbol of correlation between A-amplitude and P-pressure) was introduced to describe the time-dependent changes in correlation between amplitude and mean ICP. The RAP was significantly lower in patients who died or remained in the vegetative state. In 7 patients who died from uncontrollable intracranial hypertension RAP was oscillating or decreased to 0 or negative values well before brain-stem herniation. The combination of an ICP above 20 mmHg for a period longer than 6 hours with low correlation between the amplitude and pressure (RAP < 0.5) was described as an predictive index of an unfavourable outcome.

Crystal structure of a mammalian phosphoinositide-specific phospholipase C delta

Mammalian phosphoinositide-specific phospholipase C enzymes (PI-PLC) act as signal transducers that generate two second messengers, inositol-1,4,5-trisphosphate and diacylglycerol. The 2.4-A structure of phospholipase C delta 1 reveals a multidomain protein incorporating modules shared by many signalling proteins. The structure suggests a mechanism for membrane attachment and Ca2+-dependent hydrolysis of second-messenger precursors. The regulation and reversible membrane association of PI-PLC may serve as a model for understanding other multidomain enzymes involved in phospholipid signalling.

Childhood social circumstances and psychosocial and behavioural factors as determinants of plasma fibrinogen

BACKGROUND

High plasma fibrinogen concentration is associated with an increased risk of coronary heart disease. We have investigated associations between plasma fibrinogen and factors operating in childhood and in adulthood, including the psychosocial characteristics.

METHODS

In a cross-sectional study of Civil Servants in London, UK, 2095 men and 1202 women aged 45-55 years provided blood samples for fibrinogen measurement at the time of the Whitehall II study baseline. The participants completed a questionnaire on demographic characteristics, education, employment grade, parents' occupation, health behaviours, and work characteristics.

FINDINGS

Measures of childhood environment (adult height, father's social class, and participant's education) were inversely associated with adult plasma fibrinogen concentration in both sexes. Lower socioeconomic status (as shown by employment grade) was associated with higher fibrinogen concentrations, with differences from top to bottom grade of 0.22 g/L (95% Cl 0.13-0.31) in men and 0.37 g/L (0.18-0.56) in women (p<0.0001, both sexes). This association was not accounted for by measures of childhood circumstances. Control over work, assessed by personnel managers, was inversely related to fibrinogen in both sexes, and a similar relation was seen for self-rated control over work among men but not women. Men in the bottom third of the distribution for self-rated and externally assessed control over work had higher fibrinogen concentrations than those in the top third for both measures (difference 0.16 g//L [0.07-0.26]; p<0.001.) There was no difference between these extremes among women (0.02 g/L [0.16 to 0.19]). Current smokers had higher fibrinogen concentrations than non-smokers, and moderate alcohol consumers had lower concentrations than those who drank occasionally or never.

INTERPRETATION

Although our study was cross-sectional, it provides evidence that adult fibrinogen concentration is determined by factors operating throughout life. Fibrinogen may be a marker of the biological pathways that mediate the inverse socioeconomic gradient in coronary disease.

Is stroke incidence related to season or temperature? The Oxfordshire Community Stroke Project

BACKGROUND

A winter excess of ischaemic stroke has been found in mortality and hospital-based studies. It is often assumed that this is due to seasonal variation in stroke incidence and several pathophysiological explanations have been proposed. We studied the incidence of stroke in relation to season and outside temperature.

METHODS

The data came from a community-based study of first ever in a lifetime stroke in a defined population of about 105 000. 675 such strokes were registered over four years and the month of inset was analysed separately for cerebral infarction, primary intracerebral haemorrhage, and subarachnoid haemorrhage.

FINDINGS

There was no significant seasonal variation. The incidence of primary intracerebral haemorrhage was increased at low temperatures, but there was no significant relation between the incidence of ischaemic stroke or subarachnoid haemorrhage and temperature.

INTERPRETATION

The widely reported winter excess of ischaemic strokes may be an artifact due to referral bias in hospital-based studies and increased case fatality during the winter in mortality studies.

Transposon tools for recombinant DNA manipulation: characterization of transcriptional regulators from yeast, Xenopus, and mouse

Transposon Tn1000 has been adapted to deliver novel DNA sequences for manipulating recombinant DNA. The transposition procedure for these "tagged" Tn1000s is simple and applicable to most plasmids in current use. For yeast molecular biology, tagged Tn1000s introduce a variety of yeast selective markers and replication origins into plasmids and cosmids. In addition, the beta-globin minimal promoter and lacZ gene of Tn(beta)lac serve as a mobile reporter of eukaryotic enhancer activity. In this paper, Tn(beta)lac was used to localize a mouse HoxB-complex enhancer in transgenic mice. Other tagged transposons create Gal4 DNA-binding-domain fusions, in either Escherichia coli or yeast plasmids, for use in one- and two-hybrid tests of transcriptional activation and protein-protein interaction, respectively. With such fusions, the Saccharomyces cerevisiae Swi6 G1/S-phase transcription factor and the Xenopus laevis Pintallavis developmental regulator are shown to activate transcription. Furthermore, the same transposon insertions also facilitated mapping of the Swi6 and Pintallavis domains responsible for transcriptional activation. Thus, as well as introducing novel sequences, tagged transposons share the numerous other applications of transposition such as producing insertional mutations, creating deletion series, or serving as mobile primer sites for DNA sequencing.

Xist expression from an Xist YAC transgene carried on the mouse Y chromosome

We have constructed mouse transgenic lines carrying a YAC clone encompassing the Xist gene in order to investigate the factors influencing Xist expression and the initiation of X-inactivation. Two transgenic lines were derived, one carrying four copies integrated at an autosomal site and a second line carrying four copies integrated at a single site on the Y chromosome. Xist expression was not observed in mice carrying the autosomal insertion. However, Xist expression from the Y-inserted transgenes was observed and at levels commensurate with that found in normal female mice. Methylation sites in the autosomal transgene both 5' and 3' of the Xist gene are hypermethylated and appear to reflect methylation patterns observed on the active X chromosome. For the Y-linked transgene, methylation sites 5' and 3' of the Xist gene are hypomethylated reflecting patterns found on the inactive X chromosome. However, the 5' and 3' methylation levels have been decoupled at the active transgenic locus. The data suggest that sequences in the vicinity of Xist can initiate some of the features that are associated with the initiation process of X-inactivation.

Enzymology of the reduction of the novel fused pyrazine mono-n-oxide bioreductive drug, RB90740 roles for P450 reductase and cytochrome b5 reductase

RB90740 is the lead compound in a series of fused pyrazine mono-N-oxide bioreductive drugs. Theses agents have potential application in cancer therapy, since they are more toxic to hypoxic than to aerobic cells as a consequence of their bioactivation by cellular reductase enzymes within the hypoxic regions of a tumour. In this study, mouse liver microsomes have been used to characterise the enzymology of the reductive activation of RB90740. Under hypoxic conditions, the reduction of RB90740 to its stable 2-electron reduced product RB92815 was supported by both NADH and NADPH, the former supporting a rate approximately 80% of the latter. Combining the two cofactors had no additive effect. Neither carbon monoxide nor metyrapone inhibited reduction of RB90740, indicating that P450 isozymes were not involved in the reduction of this compound. 2' AMP, and inhibitor of P450 reductase, did not inhibit formation of RB92815, whereas DPIC, another inhibitor but with a different mode of action, inhibited both the NADH, and NADPH-dependent reduction of RB90740. Similarly, two selective inhibitors of NADH: cytochrome b5 reductase, pHMB and PTU, completely inhibited both NADH and NADPH-dependent reduction of RB90740. Our findings implicate P450 reductase, cytochrome b5 reductase, and cytochrome b5 in the activation of the compound. However, there is no clear relationship between the intracellular levels of P450 reductase and cytochrome b5 reductase and the hypoxic toxicity of RB90740, which implies that other factors, in addition to drug activation, play a major role in controlling the toxicity of this particular bioreductive drug.

Psychosocial work environment and sickness absence among British civil servants: the Whitehall II study

OBJECTIVES

This study sought to examine the association between the psychosocial work environment and subsequent rates of sickness absence.

METHODS

The analyses were based on a cohort of male and female British civil servants (n=9072). Rates of short spells (<or=7 days) and long spells (>7 days) of sickness absence were calculated for different aspects of the psychosocial work environment, as measured by self-reports and personnel managers' ratings (external assessments).

RESULTS

Low levels of work demands, control, and support were associated with higher rates of short and long spells of absence in men and, to a lesser extent, in women. The differences were similar for the self-reports and external assessments. After adjustment for grade of employment, the differences were diminished but generally remained significant for short spells. The combination of high demands and low control was only associated with higher rates of short spells in the lower grades.

CONCLUSIONS

The psychosocial work environment predicts rates of sickness absence. Increased levels of control and support at work could have beneficial effects in terms of both improving the health and well-being of employees and increasing productivity.

Characterization in vitro of an autocatalytic processing activity associated with the predicted 3C-like proteinase domain of the coronavirus avian infectious bronchitis virus

A region of the infectious bronchitis virus (IBV) genome between nucleotide positions 8693 and 10927 which encodes the predicted 3C-like proteinase (3CLP) domain and several potential cleavage sites has been clones into a T7 transcription vector. In vitro translation of synthetic transcripts generated from this plasmid was not accompanied by detectable processing activity of the nascent polypeptide unless the translation was carried out in the presence of microsomal membrane preparations. The processed products so obtained closely resembled in size those expected from cleavage at predicted glutamine-serine (Q/S) dipeptides and included a protein with a size of 35 kDa (p35) that corresponds to the predicted size of 3CLP. Efficient processing was dependent on the presence of membranes during translation; processing was found to occur when microsomes were added posttranslationally, but only after extended periods of incubation. C-terminal deletion analysis of the encoded polyprotein fragment revealed that cleavage activity was dependent on the presence of most but not all of the downstream and adjacent hydrophobic region MP2. Dysfunctional mutagenesis of the putative active-site cysteine residue of 3CLP to either serine or alanine resulted in polypeptides that were impaired for processing, while mutagenesis at the predicted Q/S release sites implicated them in the release of the p35 protein. Processed products of the wild-type protein were active in trans cleavage assays, which were used to demonstrate that the IBV 3CLP is sensitive to inhibition by both serine and cysteine protease class-specific inhibitors. These data reveal the identity of the IBV 3C-like proteinase, which exhibits characteristics in common with the 3C proteinases of picornaviruses.

Specific killing of lymphoma cells by cytotoxic T-cells mediated by a bispecific diabody

Antibody fragments produced by bacterial fermentation lack natural effector functions. Bispecific antibody fragments, however, can be endowed with effector functions, for example cell-mediated killing, by binding to and retargeting of cytotoxic cells. Diabodies are a class of engineered antibody fragments with two antigen binding sites, consisting of two associated chains; each chain consists of heavy and light chain variable domains linked by a short polypeptide linker. In contrast to IgG, or other antibody fragments in which the two binding sites can take up a range of orientations and spacings, the diabody structure is more rigid and compact, with the two binding sites separated by 65 łA (less than half the distance in IgG). To establish whether diabodies could also be used in cell-mediated killing, we have explored the use of a bispecific diabody binding to an idiotypic marker on mouse B-cell lymphoma (BCL-1) and to mouse CD3. The bispecific diabody activated naive T-cells and also mediated the specific killing of the lymphoma cells by cytotoxic T-cells. The diabody was less active in T-cell activation but 10-fold more active (w/v) in killing than an analogous bispecific IgG.

An audit of aneurysmal subarachnoid haemorrhage: earlier resuscitation and surgery reduces inpatient stay and deaths from rebleeding

OBJECTIVE

To audit the outcome in patients with subarachnoid haemorrhage (SAH) after a change in management strategy.

METHODS

A retrospective analysis of patients with aneurysmal subarachnoid haemorrhage over a 20 month period (phase 1) was followed by a prospective analysis of patients presenting during the next 20 months (phase 2) in which a protocol driven management regime of immediate intravenous fluid resuscitation and earlier surgery was pursued. Patients in this phase were grouped into those receiving early (within four days of subarachnoid haemorrhage) and late (after four days of subarachnoid haemorrhage) surgery. In phase 1, 75 out of a total of 92 patients underwent surgery on (median) day 12. From phase 2, 109 patients out of a total of 129 underwent surgery on (median) day 4, 58 of which had their surgery within 4 days of the subarachnoid haemorrhage. Patients in each phase/group were well matched for demographic features, site of aneurysm, and severity of subarachnoid haemorrhage.

RESULTS

The surgical morbidity and mortality were no different in the two phases (P < 0.92; chi2 test). The management outcomes in the two phases of the study were also no different (P < 0.52). However, there was a significant reduction in the rebleed rate in patients undergoing surgery within four days of the subarachnoid haemorrhage in phase 2 (P < 0.0001) with an associated trend towards reduced incidence of postoperative ischaemia (P = 0.06) and mortality (P = 0.11). Operating earlier in phase 2 of the trial resulted in a lower total hospital inpatient stay of 15.8 (95% CI 13.1-18.5) days for survivors compared with 25.7 (95% CI 21.6-29.8) days in the late group (P < 0.00001; t test).

CONCLUSIONS

surgical morbidity and mortality seemed independent of the timing of aneurysm surgery. Early surgery within four days was associated with a highly significant reduction in rebleed rate, and in the duration of total hospital inpatient stay.

Clinical immunity to Plasmodium falciparum malaria is associated with serum antibodies to the 19-kDa C-terminal fragment of the merozoite surface antigen, PfMSP-1

The development of an effective malaria vaccine depends upon identification of antigens that are targets of protective immune responses. An immunoepidemiologic approach has been used to investigate the relationship between antibody responses to a defined region of the major merozoite surface protein of Plasmodium falciparum (PfMSP-1 19) and resistance to clinical malaria in 2 populations of children from West Africa. After allowing for the confounding effects of age, antibodies to PfMSP-1 19 were shown the provide 40% protection against clinical malaria in children in Sierra Leone. In Gambian children, antibodies to one of the epidermal growth factor-like motifs of PfMSP-1 19 were strongly associated with resistance to both clinical malaria and high levels of parasitemia.

East-West mortality divide and its potential explanations: proposed research agenda

There is a sharp divide in mortality between eastern and western Europe, which has largely developed over the past three decades and is caused mainly by chronic diseases in adulthood. The difference in life expectancy at birth between the best and worst European countries in this respect is more than 10 years for both sexes. The reasons for these differences in mortality are not clear and data currently available permit only speculation. The contributions of medical care and pollution are likely to be modest; health behaviour, diet, and alcohol consumption seem to be more important; smoking seems to have the largest impact. There is also evidence that psychosocial factors are less favourable in eastern Europe. Available data show socioeconomic gradients in all cause mortality within eastern European countries similar to those in the West. Determinants of the mortality gap between eastern and western Europe are probably related to the contrast in their social environments and may be similar to those underlying the social gradients in mortality within countries.

A combined analysis of D22S278 marker alleles in affected sib-pairs: support for a susceptibility locus for schizophrenia at chromosome 22q12. Schizophrenia Collaborative Linkage Group (Chromosome 22)

Several groups have reported weak evidence for linkage between schizophrenia and genetic markers located on chromosome 22q using the lod score method of analysis. However these findings involved different genetic markers and methods of analysis, and so were not directly comparable. To resolve this issue we have performed a combined analysis of genotypic data from the marker D22S278 in multiply affected schizophrenic families derived from 11 independent research groups worldwide. This marker was chosen because it showed maximum evidence for linkage in three independent datasets (Vallada et al., Am J Med Genet 60:139-146, 1995; Polymeropoulos et al., Neuropsychiatr Genet 54:93-99, 1994; Lasseter et al., Am J Med Genet, 60:172-173, 1995. Using the affected sib-pair method as implemented by the program ESPA, the combined dataset showed 252 alleles shared compared with 188 alleles not share (chi-square 9.31, 1df, P = 0.001) where parental genotype data was completely known. When sib-pairs for whom parental data was assigned according to probability were included the number of alleles shared was 514.1 compared with 437.8 not shared (chi-square 6.12, 1df, P = 0.006). Similar results were obtained when a likelihood ratio method for sib-pair analysis was used. These results indicate that may be a susceptibility locus for schizophrenia at 22q12.

A systematic review of the risks of stroke and death due to endarterectomy for symptomatic carotid stenosis

BACKGROUND AND PURPOSE

Carotid endarterectomy reduces the risk of carotid territory ischemic stroke ipsilateral to a recently symptomatic severe carotid stenosis. However, the benefit is limited by the risks of stroke and death associated with the operation. Although reported surgical risks vary enormously, there has been no systematic review of the published literature.

METHODS

We performed a systematic review of mortality and the risk of stroke and/or death due to endarterectomy for symptomatic carotid stenosis in studies published since 1980.

RESULTS

Fifty-one studies fulfilled our criteria. Overall mortality was 1.62% (95% confidence interval [CI], 1.3 to 1.9), and the risk of stroke and/or death was 5.64% (95% CI, 4.4 to 6.9). However, there was significant heterogeneity of risk of stroke and/or death (P < .001). The risk varied systematically with the methods and the authorship of the study. The risk of stroke and/or death was highest in studies in which patients were assessed by a neurologist after surgery (7.7%; 95% CI, 5.0 to 10.2) and lowest in studies with a single author affiliated with a department of surgery (2.3%; 95% CI, 1.8 to 2.7). After correcting for study methodology, there was no temporal trend in the risk of stroke and/or death between 1980 and 1995.

CONCLUSIONS

The reported risks of endarterectomy for symptomatic carotid stenosis show significantly greater variability than would be expected by chance. However, much of this variability can be accounted for by differences in methodology and authorship. The 5.6% overall risk of stroke and/or death is consistent with present guidelines.

Multimodal monitoring in neurointensive care

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Local clinical guidelines: description and evaluation of a participative method for their development and implementation

BACKGROUND

National guidelines are rarely followed by immediate change in clinical behaviour. We present our experience of an active educational method for local development and implementation of a guideline.

OBJECTIVE

To evaluate the effectiveness of a participative method for developing local clinical guidelines.

METHODS

A trial in a district of the effect of guideline development incorporating active participation of intended recipients on subsequent relevant prescribing. It was carried out in Wirral Family Health Services Authority district (the Wirral peninsula) comprising 69 general practices covering a population of 345,763. An exemplar guideline on 'hypertension in the elderly' was developed by the method described. The principal recommended drug was bendrofluazide 2.5 mg once daily. The differences in prescribed daily doses (PDD) of bendrofluazide 2.5 mg tablets per quarter per 1000 prescribing units (age-weighted population) between the intervention district and England as a whole was measured.

RESULTS

Comparison of the intervention district with England data demonstrates a median difference of 122.49 PDD before and 206.34 PDD after guideline production, this change is statistically highly significant (Mann-Whitney two-tailed P < 0.0001; 95% CI = 36.51-104.77). Grouped regression analysis shows no significant difference (0.89) in slope gradients before guideline production (P = 0.35, 95% CI = -3.97-5.76), but the difference in slope gradients after (12.95) is statistically highly significant (P < 0.0001; 95% CI = 8.17-17.73). The data suggests that the change in clinical behaviour persisted for at least two years.

CONCLUSION

Participation of intended recipient general practitioners and local specialists in the development of a guideline by an active educational method as described was followed by a favourable change in clinical behaviour which persisted for at least two years.

No evidence for allelic association between schizophrenia and a polymorphism determining high or low catechol O-methyltransferase activity

OBJECTIVE

Catechol O-methyltransferase (COMT) inactivates catecholamines by methylating their m-hydroxy group. Some previous studies using biochemical methods have found higher levels of COMT activity in schizophrenic patients. Recently, the genetic polymorphism that underlies variation in COMT activity, which results in the creation of a NlaIII restriction site in the low-activity allele, has been elucidated.

METHOD

This study investigated this polymorphism in 78 unrelated schizophrenic patients and 78 comparison subjects matched for age and ethnicity. High-molecular-weight DNA was isolated from lymphocytes with routine procedures, and each individual was typed for high and low COMT activity.

RESULTS

The frequency of the NlaIII polymorphism was 0.51 in the schizophrenic patients and 0.53 in the comparison subjects, and no significant allelic or genotypic associations were observed.

CONCLUSIONS

There was no evidence for variation in COMT activity between a group of schizophrenic patients and matched comparison subjects.

Recombination associated with replication of malarial mitochondrial DNA

Mitochondrial DNA of the malarial parasite Plasmodium falciparum comprises approximately 20 copies per cell of a 6 kb genome, arranged mainly as polydisperse linear concatemers. In synchronous blood cultures, initiation of mtDNA replication coincides with the start of the 4-5 doublings in nuclear DNA that mark the reproductive phase of the erythrocytic cycle. We show that mtDNA replication coincides with a recombination process reminiscent of the replication mechanism used by certain bacteriophages and plasmids. The few circular forms of mtDNA which are also present do not replicate by a theta mechanism, but are themselves the product of recombination, and we propose they undergo rolling circle activity to generate the linear concatemers.

A comparison of the physiological effects of RSU1069 and RB6145 in the SCCVII murine tumour

The physiological and therapeutic effects of the bioreductive agent RSU1069 (80 mg/kg i.p.) and its prodrug RB6145 (240 mg/kg i.p.) were investigated in the SCCVII tumour. Using laser Doppler flowmetry it was found that RSU1069 produced a significant 30% reduction in tumour blood flow 30 min after administration, while RB6145 had no effect. Tumour oxygenation, measured with an Eppendorf oxygen electrode, was unchanged by either agent except for a reduction in values less than 2.5 mmHg at 30 min after injection. Neither agent significantly altered tumour energy metabolism, assessed by 31P magnetic resonance spectroscopy. Both agents significantly increased tumour glucose content by a factor of 1.6-1.7 at 30 min after injection, but had no effect on glucose-6-phosphate or lactate levels. Tumour growth was significantly delayed by heating (42.5 degrees C, 60 min), and although neither RSU1069 nor RB6145 alone had any effect on tumour growth they produced a similar enhancement of the tumour response to heat. The therapeutic effects are consistent with the known conversion in vivo of one third of the pro-drug RB6145 to its active product RSU1069, however the physiological effects of the two agents in the SCCVII tumour are not identical.

Linkage analysis of the fragile X gene FMR-1 and schizophrenia: no evidence for linkage but report of a family with schizophrenia and an unstable triplet repeat

We have examined 23 families multiply affected with schizophrenia for linkage to the FMR-1 gene on the X chromosome. Alleles at the FMR-1 CGG triplet repeat were analysed by the polymerase chain reaction, and methylation status at the FMR-1 locus in individuals with evidence of expanded or unstable repeats was analysed by Southern hybridization. Two-point LOD score analyses with a range of X-linked single gene models and a non-parametric affected sib-pair method revealed no evidence for linkage. In one family, however, a fragile X premutation was found, and one individual with schizophrenia and developmental delay was a mosaic for the full and premutation. We conclude that although mutations within the FMR-1 gene do not have a major aetiological role in schizophrenia in our collection of pedigrees, it is possible that FMR-1 mutations can modify the clinical phenotype of schizophrenia.

Detection of the ORF3 polypeptide of feline calicivirus in infected cells and evidence for its expression from a single, functionally bicistronic, subgenomic mRNA

Feline calicivirus (FCV) is a small positive-stranded RNA virus within the family Caliciviridae. Its genome is 7690 nucleotides in length and encodes three open reading frames (ORFs). The smallest, ORF3, is located at the extreme 3' end of the genome and can potentially encode a polypeptide of approximately 12 kDa. In this paper, we report the identification of an ORF3-encoded polypeptide in FCV-infected cells using an antiserum raised against a bacterially-expressed bacteriophage T7 gene 10-ORF3 fusion protein. Although a small mRNA of 0-5 kb, which could potentially encode ORF3, has been described, reports on the number and size of FCV subgenomic RNAs have varied considerably. To clarify the situation, RNAs from FCV-infected cells were labelled in vivo using [32P]orthophosphate, an approach which provided definitive data. Only two RNA species were detected, the genomic RNA and a subgenomic mRNA of 2.4 kb. The 5' end of the subgenomic mRNA was mapped to position 5227 on the genomic RNA using RNA sequencing and primer extension methods. RNA isolated from FCV-infected cells in which no subgenomic RNA smaller than 2.4 kb was detectable directed the synthesis in rabbit reticulocyte lysate of the ORF3-encoded polypeptide. Furthermore, a synthetic RNA copy of the 2-4 kb subgenomic mRNA of FCV, containing both ORF2 and ORF3 polypeptides in the in vitro translation system. These data strongly suggest that ORF3 is expressed from the 2-4 kb subgenomic RNA and that this RNA is functionally bicistronic. The possible mechanisms by which ORF3 is expressed are discussed.

Laboratory testing of three intracranial pressure microtransducers: technical report

Three comparatively priced intracranial pressure (ICP) microtransducers are now available, each characterized by the manufacturer as having very low zero drift over long periods, an excellent frequency response, and a low measurement error. The three microtransducers, coded Transducer A (Camino OLM ICP monitor; Camino Laboratories, San Diego, CA), Transducer B (Codman Microsensor ICP Transducer; Codman & Shurtlef Inc., Randolph, MA), and Transducer C (ICP Monitoring Catheter Kit OPX-SD [4F]; InnerSpace Medical, Irvine, CA), were examined in a pressure-flow test rig designed for assessment of hydrocephalus shunts. All three microtransducers compiled with the manufacturers' specifications and gave high-quality readings under test conditions. However, some differences were noted; Transducer C had the lowest 24-hour zero drift (drifts in all transducers were < 0.8 mm Hg). The temperature drift was very low in Transducer B and C, but Transducer A had a significantly higher drift (0.27 mm Hg/degrees C). Transducer A had a static error < 0.3 mm Hg, Transducer B < 2 mm Hg, and Transducer C < 8 mm Hg. Frequency detection in Transducers A and B were very good (bandwidth, > 30 Hz), whereas Transducer C had a limited bandwidth of 20 Hz. Transducer B scored the best overall, but all three scored satisfactorily during bench testing.

Latent and persistent infections of monocytes and macrophages

Human cytomegalovirus (HCMV), like all herpesviruses, persists in the host after primary infection, with reactivation often occurring as a result of immunosuppression. The lack of a model system has made analysis of HCMV latency and reactivation difficult. However, the ability to analyse which specific cell types in vivo carry the virus and the relative levels of permissiveness of these cell types for viral gene expression and productive infection is beginning to help us understand these complex molecular events.

Sequence analysis and genetic mapping of porcine chromosome 11 centromeric S0048 marker

We report the existence of a new family of swine centromeric satellite DNA composed of a 51-bp repeat unit, most specifically found on pig chromosome 11 centromere and with less specificity at the centromeric region of other meta- and submetacentric chromosomes. This satellite DNA family, which has no homologies with the Mc1 and Ac2 families published previously, was named Mc2. We designed a specific primer set for PCR amplification of this centromeric satellite DNA. Specificity of amplification was checked by using a porcine somatic cell hybrid panel and by FISH. Furthermore, the development of a PCR-RFLP marker of Mc2 repetition allowed its genetic mapping on the PiGMaP reference families panel. The centromere of chromosome 11 was thus integrated to the genetic map previously published.

Structural analysis of the glycosyl-phosphatidylinositol membrane anchor of the merozoite surface proteins-1 and -2 of Plasmodium falciparum

Plasmodium falciparum accumulates the two merozoite surface proteins-1 and -2 during schizogony. Both proteins are proposed to be anchored in membranes by glycosyl-phosphatidylinositol membrane anchors. In this report the identity of these GPI-anchors is confirmed by labelling with tritiated precursors and additionally by specific enzymatic and chemical treatments. Detailed structural analysis of the core-glycans showed that the GPI-anchors of both proteins possess an extra alpha 1-2 linked mannose at the conserved trimannosyl-core-glycan. MSP-1 and MSP-2 labelled with tritiated myristic acid possess primarily radioactive myristic acid at inositol rings in both GPI-anchors. Additionally the hydrophobic fragments released from [3H]myristic acid labelled GPI-anchors were identified as diacyl-glycerols, carrying preferentially [3H]palmitic acid in an ester-linkage.

Phospholipase C delta 1 requires a pleckstrin homology domain for interaction with the plasma membrane

The structural requirements of phospholipase C delta 1 for interaction with the plasma membrane were analysed by immunofluorescence after microinjection into living cells. Microinjection of deletion mutants revealed that the region required for membrane attachment and binding of inositol 1,4,5-trisphosphate in vitro corresponded to the pleckstrin homology domain, a structural module described in more than 90 proteins.

Identification of a cdk-activating kinase in fission yeast

We have identified a second cyclin-dependent kinase (cdk) in fission yeast, crk1, which encodes a 335 amino acid protein that is most closely related to the KIN28 gene product from Saccharomyces cerevisiae and to a cdk activating kinase (CAK) encoded by the MO15 gene from Xenopus laevis, crk1 is essential for viability and delta crk1 cells arrest with septa and condensed chromatin. We show that Crk1 associates with the Mcs2 mitotic catastrophe suppressor, a cyclin H-like molecule, and overexpression of crk1 rescues the cell-cycle arrest defect of a mcs2-75 cdc2-3w cdc25-22 triple mutant at high temperature. The Crk1-Mcs2 complex possesses CAK activity in vitro in that it phosphorylates human Cdk2 on Thr160 which results in its activation in the presence of cyclin A. In addition Crk1-Mcs2 effectively phosphorylates a peptide corresponding to the C-terminal repeat domain (CTD) of RNA polymerase II. We demonstrate that crk1 is allelic to the mcs6 mitotic catastrophe suppressor and that the X.laevis MO15 gene rescues the cell-cycle arrest of an mcs6-13 cdc2-3w cdc25-22 at high temperature. Together these data suggest that the Crk1-Mcs2 complex is a CAK that interacts genetically with Cdc2 in fission yeast.

Relationship between expression of topoisomerase II isoforms and intrinsic sensitivity to topoisomerase II inhibitors in breast cancer cell lines

Topoisomerase II is a key target for many anti-cancer drugs used to treat breast cancer. In human cells there are two closely related, but differentially expressed, topoisomerase II isoforms, designated topoisomerase II alpha and beta. Here, we report the production of a new polyclonal antibody raised against a fragment of the C-terminal domain of the 180 kDa form of topoisomerase II (the beta isoform), which does not cross-react with the 170 kDa form (the alpha isoform). Using this antibody, together with a polyclonal antibody specific for the 170 kDa isoform of topoisomerase II, we have examined the relationship between the sensitivity of a panel of human breast cancer cell lines to different classes of topoisomerase II inhibitors and cellular levels of the topoisomerase II alpha and beta proteins. We found that sensitivity to amsacrine showed a correlation with the level of expression of topoisomerase II alpha protein, and that sensitivity to etoposide showed a similar correlation with the level of expression of topoisomerase II beta protein. There was also a relationship between sensitivity of these cell lines to mitoxantrone and the cellular level of both isoforms of topoisomerase II. No relationship was found between the level of mRNA for topoisomerase II alpha or beta, and either sensitivity of breast cancer cell lines to topoisomerase II inhibitors or the level of topoisomerase II protein expression.

Psychological factors in the relationship between alcohol and cardiovascular morbidity

Most major studies have found a U-shaped relationship between the level of alcohol consumption and all cause mortality, largely as a consequence of lower death rates from coronary heart disease (CHD) amongst moderate drinkers. Previous attempts to unravel the significance of this observation have focused on controlling for possible confounders, such as smoking, social class and the existence of previous ill-health in the group of abstainers. Our analysis of data from the Whitehall II study of British Civil Servants sought to determine whether psychological factors (GHQ, Hostility, Affect Balance, Social Supports) may be influencing the observed relationships between levels of alcohol consumption and some of the established risk factors for CHD. We found evidence of weak confounding only with respect to levels of apolipoprotein B (APoB) and as such have failed to provide compelling evidence that the U-shaped relationship between alcohol and CHD mortality could be easily explained by psychosocial confounding. At the same time we would not claim that the measures we have used are either flawless or exhaust the range of psychological variables that might plausibly influence physiological mediators of cardiovascular disease.

Can cerebrovascular reactivity be measured with near-infrared spectroscopy?

BACKGROUND AND PURPOSE

We used near-infrared spectroscopy (NIRS) to monitor the cerebral oxygenation changes during CO2 reactivity tests.

METHODS

Fifty healthy volunteers were examined (age range, 19 to 68 years). The monitored parameters were as follows: transcranial Doppler (TCD) time-averaged middle cerebral artery flow velocity end-tidal CO2 (EtCO2); change in concentration of cerebral oxyhemoglobin (HbO2), deoxyhemoglobin (Hb), and total hemoglobin; mean arterial blood pressure; peripheral arterial oxygen saturation (SaO2); and extracranial tissue perfusion with the use of cutaneous laser-Doppler flowmetry. The examination protocol included both hypercapnia and hypocapnia. The cerebrovascular reactivity indexes were calculated as follows: TCD, relative change in flow velocity per 1 kPa increase in EtCO2; NIRS, absolute change in HbO2, Hb, and total hemoglobin concentration (micromoles per liter) per 1 kPa increase in EtCO2.

RESULTS

Mean middle cerebral artery flow velocity was found to be 58 cm/s at a mean baseline EtCO2 of 4.7 kPa. Mean cerebrovascular reactivities were as follows: TCD, 24%/kPa (SEM, 1.1); HbO2, 2.06 mumol/L per kilopascal (SEM, 0.08); Hb, -0.63 mumol/L per kilopascal (SEM, 0.09); and total hemoglobin concentration, 1.44 mumol/L per kilopascal (SEM, 0.1). Statistical analysis revealed significant correlation between reactivities calculated with the use of NIRS and TCD (P < .001). Although some fluctuations were observed in SaO2 and laser-Doppler flux, they were not correlated with either EtCO2 or NIRS.

CONCLUSIONS

NIRS signal changes in HbO2, Hb, and total hemoglobin concentration are very sensitive to alterations in EtCO2, which are largely independent of extracranial tissue perfusion. NIRS may be developed as an alternative method for testing cerebrovascular reactivity and may be of particular clinical importance when the ultrasound window is poor.