The influence of the milieu on the rate of neutralisation of herpes simplex virus 1

The rate of neutralisation of herpes simplex virus 1 was increased by up to more than five hundred-fold when the virus suspension and antiserum were each diluted to one hundred-fold in water instead of phosphate buffered saline. This phenomenon, which was observed for two human positive sera and a rabbit purified polyclonal antibody, may represent an unrecognised homeostatic mechanism where neutralising antibody is 'dilution-fast' under physiological conditions of transudation or pathological conditions of inflammation.

Persephin, a novel neurotrophic factor related to GDNF and neurturin

A novel neurotrophic factor named Persephin that is approximately 40% identical to glial cell line-derived neurotrophic factor (GDNF) and neurturin (NTN) has been identified using degenerate PCR. Persephin, like GDNF and NTN, promotes the survival of ventral midbrain dopaminergic neurons in culture and prevents their degeneration after 6-hydroxydopamine treatment in vivo. Persephin also supports the survival of motor neurons in culture and in vivo after sciatic nerve axotomy and, like GDNF, promotes ureteric bud branching. However, in contrast to GDNF and NTN, persephin does not support any of the peripheral neurons that were examined. Fibroblasts transfected with Ret and one of the coreceptors GFRalpha-1 or GFRalpha-2 do not respond to persephin, suggesting that persephin utilizes additional, or different, receptor components than GDNF and NTN.

Anticardiolipin antibodies in clinical conditions associated with a risk of thrombotic events

Anticardiolipin antibodies (ACAs) of IgA, IgG, and IgM isotypes were measured using an enzyme-linked immunosorbent assay (ELISA) in patients with SLE, and in other groups of subjects with a higher or lower risk of developing thrombosis. IgA ACAs were present in high titers in all groups and had little discriminant value in predicting thrombotic risk. In patients without the lupus anticoagulant (LAC) with conditions in which a thrombotic tendency was a feature (primigravidae with preeclampsia or intrauterine growth retardation, patients with angina or acute myocardial infarction, those on anticoagulant therapy for apparently spontaneous thrombosis, and patients with Behcet's syndrome in whom there was a history of thrombosis) ACAs of all isotypes were present in 44/191 (23%). In patients in whom a thrombotic tendency was not a feature (normal controls, primigravidae with normal deliveries, patients with rheumatoid arthritis, and with Behcet's syndrome in whom there was no thrombotic history) 22/241 (9%) had ACAs. Although ACAs were more likely to be present in a subset of patients without systemic lupus erythematosus (SLE) and/or the LAC, their presence was a poor discriminator of increased risk of thrombosis.

A longitudinal study of the dental care of adults in the general dental service in Scotland: the first 6 years, 1988-1994

OBJECTIVE

To provide an overview of routine dental care for adults attending the general dental service in Scotland, in a more detailed manner than is currently possible from national data sets.

DESIGN AND SETTING

Cohort study in the general dental service.

SUBJECTS AND METHODS

The cohort consisted of 992 Scottish dentate adults who participated in the adult dental health survey of 1988, conducted by the Office of Population Censuses and Surveys. Details of subsequent treatment undertaken in the general dental service were provided by Dental Practice Division, Edinburgh.

MAIN OUTCOME MEASURES

Production of patient-specific and tooth-specific data on dental attendance and treatment.

RESULTS

71% of the cohort attended at least once in the 6 years. Registration levels, following the introduction of the continuing care contract, reached 42-44%. Observed lapses in registration illustrate the changing membership of the relatively static level of registration year-on-year. Vulnerability to treatment of different tooth sites is illustrated graphically.

CONCLUSIONS

Cohort studies provide valuable information on patterns of attendance and treatment needed for planning of dental health services. Growing computer power and increasing demands for management data may mean that future work of this nature can be more appropriately undertaken at the population level.

Drosophila Shaking-B protein forms gap junctions in paired Xenopus oocytes

In most multicellular organisms direct cell-cell communication is mediated by the intercellular channels of gap junctions. These channels allow the exchange of ions and molecules that are believed to be essential for cell signalling during development and in some differentiated tissues. Proteins called connexins, which are products of a multigene family, are the structural components of vertebrate gap junctions. Surprisingly, molecular homologues of the connexins have not been described in any invertebrate. A separate gene family, which includes the Drosophila genes shaking-B and l(1)ogre, and the Caenorhabditis elegans genes unc-7 and eat-5, encodes transmembrane proteins with a predicted structure similar to that of the connexins. shaking-B and eat-5 are required for the formation of functional gap junctions. To test directly whether Shaking-B is a channel protein, we expressed it in paired Xenopus oocytes. Here we show that Shaking-B localizes to the membrane, and that its presence induces the formation of functional intercellular channels. To our knowledge, this is the first structural component of an invertebrate gap junction to be characterized.

The development of the kidney

This chapter describes the earlier stages of development of the vertebrate metanephric kidney. It focuses on the mouse and descriptive morphology is used for considering both molecular mechanisms, underpinning kidney morphogenesis and differentiation, and the ways in which these processes can go awry and lead to congenital kidney disorders—particularly in humans. The mature kidney is a fairly complex organ attached to an arterial input vessel and two output vessels, the vein and the ureter. Inside, the artery and vein are connected by a complex network of capillaries that invade a large number of glomeruli, the proximal entrance to nephrons, which are filtration units that link to an arborized collecting-duct system that drains into the ureter. The ability of the kidney and isolated metanephrogenic mesenchyme, to develop in culture means that the developing tissues can be subjected to a wide variety of experimental procedures designed to investigate their molecular and cellular properties and to test hypotheses about developmental mechanisms.

The effect of losigamone (AO-33) on electrical activity and excitatory amino acid release in mouse cortical slices

1. Losigamone is a novel anticonvulsant the mechanism of action of which is not known. This study investigated the effect of losigamone on spontaneous, NMDA- and AMPA-induced depolarizations in the cortical wedge preparation of the DBA/2 mouse (which are susceptible to sound-induced seizures) and on endogenous amino acid release from BALB/c mouse cortical slices. 2. Cortical wedges exhibit spontaneous depolarizations in magnesium-free medium and losigamone was effective in significantly reducing these spontaneous depolarizations at concentrations of 100 microM and above. 3. NMDA-induced depolarizations were significantly reduced by losigamone at concentrations of 25 microM and above. Losigamone had no effect on AMPA-induced depolarizations. 4. Veratridine (20 microM) and potassium (60 mM) were used to stimulate the release of amino acids from mouse cortex. Veratridine-stimulated release of glutamate was significantly reduced by losigamone at concentrations of 100 microM and above, while potassium-stimulated release was significantly reduced by losigamone at 200 microM. 5. NMDA antagonism and inhibition of excitatory amino acid release may contribute to the anticonvulsant effect of losigamone.

Design considerations for small, special-system developmental databases

Small developmental databases, devoted to special systems and run by a normal research laboratory, differ qualitatively as well as quantitatively from larger databases described elsewhere in this volume. Resource limits set different optimum balances between computing elegance and ease of construction, while flexibility of design and semantics often assume greatest importance because specialist research databases are most useful when understanding of the biology is partial and still evolving. In this article we discuss the main considerations when building a small database-scope, access, data input, storage, searching and semantics-and illustrate them with examples of real working databases.Copyright 1997 Academic Press Limited Copyright 1997Academic Press Limited

A subtractive cDNA library from an identified regenerating neuron is enriched in sequences up-regulated during nerve regeneration

We have constructed a subtractive cDNA library from regenerating Retzius cells of the leech, Hirudo medicinalis. It is highly enriched in sequences up-regulated during nerve regeneration. Sequence analysis of selected recombinants has identified both novel sequences and sequences homologous to molecules characterised in other species. Homologies include alpha-tubulin, a calmodulin-like protein, CAAT/enhancer-binding protein (C/EBP), protein 4.1 and synapsin. These types of proteins are exactly those predicted to be associated with axonal growth and their identification confirms the quality of the library. Most interesting, however, is the isolation of 5 previously uncharacterised cDNAs which appear to be up-regulated during regeneration. Their analysis is likely to provide new information on the molecular mechanisms of neuronal regeneration.

Molecular aspects of the epithelial phenotype

Epithelia can be defined morphologically as tissues that line surfaces, and ultrastructurally with reference to their cells' apico-basal polarity and possession of specific cell-cell junctions. Defining the epithelial phenotype at a molecular level is more problematic--while it is easy to name proteins (e.g. keratins) expressed by a 'typical' epithelium, no known molecules are expressed by every epithelium but by no other tissues. Cells can differentiate to and from the epithelial state as part of normal development, as a response to disease or when manipulated in culture. Many factors (matrix components, adhesion molecules, growth factors, transcription factors) have been identified that can trigger these transitions of phenotype in specific cases, but to date no general master regulators of the epithelial state have been found. The epithelial state may therefore be controlled by multiple regulatory genes so that there is no single molecule responsible for all of the diverse types of epithelium that exist in higher animals.

Molecular cloning and expression pattern of rpr-1, a resiniferatoxin-binding, phosphotriesterase-related protein, expressed in rat kidney tubules

Bacterial phosphotriesterases are enzymes that hydrolyse phosphotriester-containing organophosphate pesticides. Resiniferatoxin is a vanilloid that desensitises nociceptive neurons. By screening a rat cDNA library with labelled resiniferatoxin, we unexpectedly isolated a novel rat phosphotriesterase homologue, here named rpr-1, that encodes a 349 amino acid, 39 kDa protein (confirmed by in vitro translation). Northern blotting and in situ hybridisation show expression primarily in proximal tubules of the kidney, in which rpr-1 distribution correlates with resiniferatoxin-binding activity. These results suggest an unsuspected link between the phosphotriesterase enzyme family and resiniferatoxin toxicity and pharmacology.

Glutamate receptor antagonists reduce spontaneous epileptiform activity in cortical wedges prepared from DBA/2 mice

This study investigated the involvement of glutamatergic neurotransmission in the epileptiform activity demonstrated in cortical weges prepared from genetically audiogenic seizure-prone DBA/2 mice. Omission of Mg2+ from the perfusing medium initiated spontaneous epileptiform events with accompanying afterpotentials on the repolarizing phase. These spontaneous depolarizations also occurred in some 30% of the slices in the presence of Mg2+ (2 mM). The N-methyl-D-aspartate (NMDA) receptor antagonist 3-(2-carboxypiperazin-4-yl)-propenyl-1-phosphonic acid (CPP) and the non-competitive NMDA receptor channel blocker ketamine produced a significant reduction of these spontaneous depolarizations. 7-Chlorokynurenic acid (7-CKA), an antagonist at the strychnine-insensitive site on the NMDA receptor, also exerted an inhibitory effect. In addition the AMPA/kainate receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX) suppressed the spontaneous events. These observations provide evidence that glutamatergic neurotransmission contributes to the epileptiform activity in this cortical preparation.

Promotion of regeneration and axon growth following injury in an invertebrate nervous system by the use of three-dimensional collagen gels

We describe the application of three-dimensional collagen matrices to the study of nerve cord repair in the leech. Our experiments show that ganglia and connectives of the leech ventral nerve cord can be maintained for up to four weeks embedded in 3D gels constructed from mammalian type I collagen. Severed nerve cords embedded in the collagen gel reliably repaired within a few days of culture. The gel was penetrable by cells emigrating from the cut ends of nerves and connectives, and we consistently saw regenerative outgrowth of severed peripheral and central axons into the gel matrix. Thus, 3D gels provide an in vitro system in which we can reliably obtain repair of severed nerve cords in the dish, and visualize cell behaviour underlying regenerative growth at the damage site: and which offers the possibility of manipulating the regenerating cells and their extracellular environment in various ways at stages during repair. Using this system it should be possible to test the effect on the repair process of altering expression of selected genes in identified nerve cells.

Haemostatic and haemodynamic abnormalities associated with left atrial thrombosis in non-rheumatic atrial fibrillation

OBJECTIVE

To evaluate the role of haemostatic and haemodynamic variables in left atrial thrombosis in non-rheumatic atrial fibrillation.

DESIGN

Case-control study.

SUBJECTS

One hundred and nine patients with non-rheumatic atrial fibrillation.

INTERVENTIONS

Peak blood velocity measured at three sites in the left atrium. Venous blood sampled for coagulant proteins and markers of haemostatic activation.

MAIN OUTCOME MEASURES

Presence of left atrial thrombus and spontaneous echo contrast at transoesophageal echocardiography.

RESULTS

Left atrial thrombus was identified in 19 patients (18%), 16 of whom had spontaneous echo contrast. Patients with thrombus had reduced peak left atrial appendage velocity compared with those without (0.17 v 0.26 m/s; P < 0.001), but no significant reductions in peak mid-left atrial or mitral valve outflow velocity. Patients with thrombus had increased plasma markers of platelet activation-beta thromboglobulin (56.8 v 30.4 IU/ml; P < 0.001) and platelet factor 4 (6.1 v 3.5 IU/ml; P < 0.01)-and of thrombogenesis: thrombin-antithrombin complexes (5.59 v 3.06 micrograms/ml; P < 0.001) and D-dimers (479 v 298 ng/ml; P < 0.01). von Willebrand factor was also increased (1.81 v 1.52 IU/ml; P < 0.05). A multiple logistic regression model identified left atrial appendage velocity (P = 0.001), beta thromboglobulin (P = 0.002), and von Willebrand factor (P = 0.04) as the independent associates of left atrial thrombosis, ahead of the presence of spontaneous echo contrast.

CONCLUSIONS

Haemostatic and haemodynamic abnormalities are associated with left atrial thrombus in non-rheumatic atrial fibrillation, and may help stratify thromboembolic risk.

Tigabine hydrochloride, an inhibitor of gamma-aminobutyric acid (GABA) uptake, induces cortical depolarizations in vitro

The effect of the gamma-aminobutyric acid uptake inhibitor tiagabine hydrochloride was studied on electrical responses in cortical wedges prepared from 20-30 day-old, audiogenic seizure-prone DBA/2 mice. Perfusion of tiagabine (50 microM) for 15 min, evoked large, slow depolarizations with a frequency of 6-8/h which persisted for 4-5 h. The GABA(A) receptor antagonists, bicuculline (10 microM) and picrotoxin (100 microM), inhibited established depolarizations. These depolarizations were also calcium-dependent and blocked by tetrodotoxin. The non-opioid antitussive, dextromethorphan, which has been shown to inhibit glutamate release, irreversibly blocked the depolarizations. Conversely, 4-aminopyridine (50 microM), a potassium channel antagonist, markedly potentiated the responses. The NMDA receptor antagonist, 3-((R)-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid, had no effect on the depolarizations at concentrations up to 100 microM but the AMPA/kainate receptor antagonist, 6,7-dinitroquinoxaline-2.3-dione at high concentrations (100 and 200 microM), reversibly decreased the frequency without affecting the amplitude. It is concluded that the tiagabine-induced depolarizations in this in vitro preparation were initiated through GABA(A) receptors leading, possibly, to a release of excitatory amino acids.

Remacemide hydrochloride: a novel antiepileptic agent

1. Remacemide hydrochloride has been shown to possess anticonvulsant activity in a wide range of animal models of epilepsy with ED50s in the 6-60 mg/kg range, depending on the species and route of administration. The compound also has been shown to be effective clinically as add-on therapy for partial seizures. 2. Degradation of remacemide yields the desglycinated metabolite that is approximately 2-fold more potent as an anticonvulsant agent than the parent drug. 3. Both compounds displace [3H]MK801 binding from the cerebral cortical membranes, and the metabolite is approximately 150-fold more potent in doing so than remacemide. This effect, together with the findings that the desglycinate reduces N-methyl-D-aspartate (NMDA)-induced depolarizations in a variety of preparations, suggests that the mechanism of action is through blockade of the channel site of the NMDA-receptor complex. 4. Remacemide and its metabolite, in common with other antiepileptic agents, block sustained repetitive-firing in cultured neurons. The metabolite also has been shown to decrease glutamate release from cortical slices. 5. Remacemide hydrochloride has neuroprotective properties when tested on models of cerebral ischemia. 6. The drug has low toxicity in contrast to other NMDA-channel-blocking compounds, such as MK801 and phencyclidine, probably because of its low affinity for the channel-binding site.

Plasminogen activator inhibitor-1 (PAI-1) 4G/5G promoter polymorphism and levels in subjects with cerebrovascular disease

The exact role of the fibrinolytic system in the pathogenesis of stroke remains to be established. Elevated circulating levels of plasminogen activator inhibitor-1, the principle inactivator of the fibrinolytic system, have been related to the development of myocardial infarction. There is evidence that a polymorphism in the promoter region of the PAI-1 gene is associated with circulating PAI-1 levels. We studied a common single nucleotide insertion/deletion (4G/5G) polymorphism by PCR in 558 patients with stroke, the pathological type of which was established by cranial computed tomography, and in 172 controls. 4G/5G genotype and PAI-1 activity were investigated in relation to 1) stroke type and 2) mortality occurring within four weeks, three months and six months of the stroke. No difference in genotype frequency was observed when all cases of stroke were compared with controls nor between the clinically determined subtypes of cerebral infarction. PAI-1 activity was significantly higher in patients with stroke (n = 245) both at presentation (11.6 U/ml) and after three months (11.8 U/ml), in paired samples, than in control subjects (8.8 U/ml, p < 0.0001). Thirty-seven (6.2%), 86 (14.5%) and 122 (20.5%) patients had died within one, three and six months of admission, respectively. PAI-1 activity was independently associated with all-cause mortality at one and three months after stroke (p = 0.02 and p = 0.03 respectively), but not after six months. In this population the 4G/5G promoter polymorphism is not associated with an increased risk of stroke. PAI-1 levels were elevated at the time of acute stroke which persisted after three months. PAI-1 level but not genotype was associated with early mortality following stroke.

Effects of felbamate on veratridine- and K(+)-stimulated release of glutamate from mouse cortex

Felbamate is a novel anticonvulsant which may modulate the strychnine-insensitive glycine site of the N-methyl-D-aspartate (NMDA) receptor complex. This study examined the effect of felbamate and 5,7-dichlorokynurenic acid on veratridine (20 microM)- and K+ (60 mM)-stimulated release of amino acids in mouse cortical slices. Felbamate significantly decreased veratridine-induced release of glutamate at 400 microM and 800 microM but had no effect on K(+)-stimulated release. 5,7-Dichlorokynurenic acid had no effect on amino-acid release in concentrations up to 200 microM. The inhibitory effect of felbamate on veratridine-induced release of glutamate may be due to inactivation of voltage-sensitive Na+ channels.

The effect of different microtitre plates on the enzyme-linked immunosorbent assay (ELISA) for anticardiolipin antibodies (ACAs)

Studies have shown an association between the presence of ACAs, measured by an ELISA, and thrombosis, foetal loss and thrombocytopenia. Most patients with the syndrome have systemic lupus erythematosus (SLE) or a related autoimmune disease. In studies of the rates of thrombotic episodes in patients with the lupus anticoagulant (LAC) and, or ACAs associated with SLE and non- SLE diseases there is considerable variation. For instance, investigations of women with a poor obstetric history: 13.1% had ACAs, 42.4%, 81.5%, others have found a lower frequency of habitual aborters with the LAC and, or ACAs arguing that ACAs play only a minor role in spontaneous abortion.

Iron-based second-sphere contrast agents for magnetic resonance imaging: development of a model system and evaluation of iron (III) tris (tironate) complex in rats

RATIONALE AND OBJECTIVES

Iron(III) complexes have been developed as magnetic resonance (MR) contrast agents based on the use of ligands capable of providing coordinative saturation at iron and allowing the second-sphere hydrogen bonding of water molecules.

METHODS

Studies of solution-phase binding of a probe ion to a diamagnetic metal catecholate complex and molecular orbital calculations were performed. R1 values were determined. Toxicity studies of iron(III) tris(tironate) were conducted with rats. Excretion studies were performed by analysis of urine samples. MR measurements were made.

RESULTS

Second-sphere coordination of a probe ion to a metal catecholate complex occurred in solution. Molecular orbital calculations suggested flexibility in design. Iron(III) tris (catecholate) complexes were shown to have high R1 values. Images of the kidneys and liver showed dose-dependent enhancement in T1-weighted images. The onset of toxicity was at approximately 0.30 mmol/kg. Urine analysis indicated essentially complete clearance (0.1-0.2 mmol/kg) within 24-48 hours.

CONCLUSION

Interactions between water molecules and basic sites within a paramagnetic metal-ligand complex allow for application of suitable complexes as T1 agents.

The Chief Scientist reports ... Monitoring the dental health of Scottish children using routinely collected data

Since the introduction in 1990 of the capitation scheme of payment for the dental care of children, information for those children registered in the scheme has been collected by General Dental Practitioners on a regular (usually annual) basis using form GP17C. These forms are processed centrally by the Dental Practice Division in Edinburgh. The information collected includes data on the dental caries experience of the child as assessed by the dentist. This paper considers some of the problems associated with the collection of this data, as currently undertaken, and its potential usefulness in monitoring the dental health of Scottish children.

Growth of herpes simplex type 1 on skin explants of atopic eczema

In a novel approach to looking at why some children with atopic eczema are susceptible to cutaneous herpes simplex virus (HSV) infections, this study evaluates the hypothesis that HSV replicates more easily on eczematous than normal skin. Growth of HSV on eczematous skin explants was compared with growth on explants from three control groups (psoriasis, Darier's disease and normal skin) over a 2-day period. Growth of HSV was significantly less on normal skin than in atopic eczema, psoriasis and Darier's disease. Virus replicated more quickly, and grew to higher titre within 24h, in eczematous and psoriatic explants than in normal skin. A defect in skin barrier function and host defence factors including local cytokine secretion are discussed as possible mechanisms in causing the increased susceptibility of children with atopic eczema to HSV infection.

Angiotensin-converting enzyme insertion/deletion polymorphism and cerebrovascular disease

BACKGROUND AND PURPOSE

There is evidence that an allelic variation in the angiotensin-converting enzyme (ACE) gene may confer an increased risk of vascular disease. The roles of the ACE insertion/deletion polymorphism and circulating ACE levels are unknown in cerebrovascular disease.

METHODS

We studied an insertion/deletion polymorphism within intron 16 of the ACE gene by polymerase chain reaction and plasma ACE activity in 467 cases of stroke, the pathological type of which was established by cranial CT, and 231 control subjects. ACE genotype and activity were related to stroke type and mortality at 4 weeks and 3 months.

RESULTS

No difference in genotype frequency was observed between all subjects with stroke and control subjects or between control subjects and subjects with cerebral infarction or cerebral hemorrhage. Plasma ACE activity was significantly lower in stroke patients at presentation (64.1 IU/L) than in control subjects (79.6 IU/L; P<.0001). Twenty-one patients (4.5%) with cerebral infarction died within 4 weeks and 56 patients (12%) within 3 months. These patients had significantly lower plasma ACE activity than patients who survived. There was some evidence that risk of death within 4 weeks increased with the number of D alleles (P=.02). Among survivors, plasma ACE activity showed a mean increase of 6.9 IU/L (95% confidence interval, 3.0 to 10.8) between levels at presentation and at 3 months (73.6 IU/L), the latter being similar to ACE activity in control subjects.

CONCLUSIONS

Low ACE activity at sroke presentation and possession of the D allele may be associated with increased risk of early death from acute cerebral infarction.