Identification and characterization of a beta proteasome subunit cluster in the Japanese pufferfish (Fugu rubripes)

The low molecular mass polypeptide (LMP2, LMP7, and MECL-1) genes code for beta-type subunits of the proteasome, a multimeric complex that degrades proteins into peptides as part of the MHC class I-mediated Ag-presenting pathway. These gene products are up-regulated in response to infection by IFN-gamma and replace the corresponding constitutively expressed subunits (X, Y, and Z) during the immune response. In humans, the LMP2 and LMP7 genes both reside within the class II region of the MHC (6p21.3), while MECL-1 is located at 16q22.1. In the present study, we have identified all three IFN-gamma-regulated beta-type proteasome subunits in Fugu, which are present as a cluster within the Fugu MHC class I region. We show that in this species, LMP7, LMP2, and MECL-1 are linked. Also within this cluster is an LMP2-like subunit (which seems specific to all teleosts tested to date) and a closely linked LMP7 pseudogene, indicating that within Fugu and potentially other teleosts, there has been an additional regional duplication involving these genes.

Bone density changes during two years treatment with tibolone or conjugated estrogens and norgestrel, compared with untreated controls in postmenopausal women

OBJECTIVE

To quantify and compare the effect of two different hormone replacement therapy regimens on bone mineral density (BMD) and serum alkaline phosphate levels against a group of no treatment control volunteers.

METHODS

An open 104-week comparative study of 113 early postmenopausal women. Fifty volunteered for the no treatment arm; the remainder were randomized to tibolone (T) (n = 32) or conjugated estrogens plus sequential norgestrel (CEEP) (n = 31). BMD was measured at baseline and after 48 and 96 weeks by dual photon absorptiometry.

RESULTS

Baseline BMD was lower in nontherapy controls and with women assigned to CEEP compared with the T group. Statistical significance was not reached. By 96 weeks, increased BMD was observed with both therapies at all sites, whereas controls had lost bone compared with baseline. Changes from baseline with both preparations were significantly different (p < 0.05) from changes in controls for all sites, except femoral neck where the change was significant only with CEEP (p < 0.05). Alkaline phosphatase was significantly reduced in both treatment groups compared with controls (p < 0.05) at 48 and 96 weeks.

CONCLUSIONS

The significant increases in BMD with T and CEEP confirm both regimens are effective in preventing osteoporosis. Without treatment, BMD declines postmenopausally.

Differences in circulating concentrations of total, free and bound leptin relate to gender and body composition in adult humans

We describe a radioimmunoassay (RIA) for total leptin and a gel filtration procedure for the separation of free and bound leptin in human serum. The RIA, based on a locally prepared antibody, has a minimum detection limit of 0.9 ng/mL, a working range (CV < 10%) of 2.5-50 ng/mL, inter-assay precision of 10.2, 7.2 and 8.9%CV at 7.9, 15.4 and 30.0 ng/mL, respectively, 94% recovery of exogenous leptin (range 81.1-120.6%), exhibited parallelism and demonstrated no significant cross-reactivity or interferences. A difference plot of results from this method and those from a commercially available kit (Linco Research) demonstrated satisfactory agreement up to concentrations of 50 ng/mL total leptin, with no significant bias. A gender-dependent correlation was obtained between body mass index (BMI) and total leptin (r = 0.91, P<0.001, n = 75 for men; r = 0.79, P<0.001, n = 72 for women), with women having higher leptin concentrations than men for any given BMI. Gel filtration studies (inter-assay precision: 4.7%CV, n = 18) demonstrated that a variable fraction (between 10% and 40%) of total leptin in serum was bound with high affinity (Keq = 1.0-1.45 x 10(9) L/mol) to a non-albumin, non-lipid macromolecule. Binding affinities were found to be similar irrespective of gender or fat mass. A significant positive correlation between free or bound leptin concentrations and BMI was obtained for both men and women (r = 0.87-0.94); free and bound leptin concentrations were also significantly higher in women (P<0.01) than in men for any given BMI, and higher in obese (P<0.01) than in lean individuals. We conclude that leptin 'resistance' associated with obesity cannot be accounted for by reduced free leptin concentrations in serum and that the methods described are suitable for the investigation of total, free and bound leptin for both clinical and research purposes.

Calcium-stimulated insulin secretion in diffuse and focal forms of congenital hyperinsulinism

OBJECTIVES

To identify infants with hyperinsulinism caused by defects of the beta-cell adenosine triphosphate-dependent potassium channel complex and to distinguish focal and diffuse forms of hyperinsulinism caused by these mutations.

STUDY DESIGN

The acute insulin response to intravenous calcium stimulation (CaAIR) was determined in 9 patients <20 years with diffuse hyperinsulinism caused by defective beta-cell sulfonylurea receptor (SUR1(-/-)), 3 patients with focal congenital hyperinsulinism (6 weeks to 18 months), a 10-year-old with insulinoma, 5 with hyperinsulinism/hyperammonemia syndrome caused by defective glutamate dehydrogenase (6 months to 28 years), 4 SUR1(+/-) heterozygotes with no symptoms, and 9 normal adults. Three infants with congenital focal disease, 1 with diffuse hyperinsulinism, and the child with insulinoma underwent selective pancreatic intra-arterial calcium stimulation with hepatic venous sampling.

RESULTS

Children with diffuse SUR1(-/-) disease and infants with congenital focal hyperinsulinism responded to CaAIR, whereas the normal control group, patients with hyperinsulinism/hyperammonemia syndrome, and SUR1(+/-) carriers did not. Selective arterial calcium stimulation of the pancreas with hepatic venous sampling revealed selective, significant step-ups in insulin secretion that correlated anatomically with the location of solitary lesions confirmed surgically in 2 of 3 infants with congenital focal disease and in the child with insulinoma. Selective arterial calcium stimulation of the pancreas with hepatic venous sampling demonstrated markedly elevated baseline insulin levels throughout the pancreas of the infant with diffuse hyperinsulinism.

CONCLUSIONS

The intravenous CaAIR is a safe and simple test for identifying infants with diffuse SUR1(-/-) hyperinsulinism or with focal congenital hyperinsulinism. Preoperative selective arterial calcium stimulation of the pancreas with hepatic venous sampling can localize focal lesions causing hyperinsulinism in children. The combination of these calcium stimulation tests may help distinguish focal lesions suitable for cure by local surgical resection.

Randomized comparison of unfractionated heparin with corticosteroids in severe active inflammatory bowel disease

BACKGROUND

Heparin therapy may be effective in steroid resistant inflammatory bowel disease.

AIM

A randomized pilot study, to compare unfractionated heparin as a first-line therapy with corticosteroids in colonic inflammatory bowel disease.

METHODS

Twenty patients with severe inflammatory bowel disease (ulcerative colitis, n=17; Crohn's colitis, n=3) were randomized to either intravenous heparin for 5 days, followed by subcutaneous heparin for 5 weeks (n=8), or high-dose intravenous hydrocortisone for 5 days followed by oral prednisolone 40 mg daily, reducing by 5 mg per day each week (n=12). After 5 days, non-responders in each treatment group were commenced on combination therapy. Response to therapy was monitored by: clinical disease activity (ulcerative colitis: Truelove and Witt Index; Crohn's colitis: Harvey and Bradshaw Index), stool frequency, serum C-reactive protein and alpha1 acid glycoprotein, endoscopic and histopathological grading.

RESULTS

The response rates were similar in both treatment groups: clinical activity index (heparin vs. steroid; 75% vs. 67%; P=0.23), stool frequency (75% vs. 67%; P=0.61), endoscopic (75% vs. 67%; P=0.4) and histopathological grading (63% vs. 50%; P=0.67). Both treatments were well-tolerated with no serious adverse events.

CONCLUSION

Heparin as a first line therapy is as effective as corticosteroids in the treatment of colonic inflammatory bowel disease. Large multicentre randomized comparative studies are required to determine the role of heparin in the management of inflammatory bowel disease.

Separation of coherent and incoherent nonlinearities in a heterodyne pump-probe experiment

We demonstrate that the transient coherent nonlinearity (coherent artifact) affecting the pump-probe response of semiconductor optical amplifiers can be experimentally separated from the incoherent transient. The technique is based on measuring the mirror component of the coherent artifact which is a background-free four--wave mixing signal at a different frequency with respect to the transmitted probe in a heterodyne detection scheme. Measurements on amplifiers of different length reveal strong deviations from the commonly expected symmetric shape of the coherent artifact in case of long waveguides.

The potential for drug interactions with statin therapy in Ireland

BACKGROUND

Seven percent of acute hospital admissions result from adverse drug reactions, of which 25% are due to drug interactions. Adverse effects of statin drugs occur in 3% of patients, mainly due to co-prescribing with other lipid-lowering agents or agents that alter their metabolism.

AIM

The aim of this study was to investigate co-prescribing of the frequently-used statin medications with interacting drugs.

METHODS

Data from the General Medical Services (GMS) scheme of the Eastern Health Board from January to December 1998 were used in this study. Using the coding index for statins, co-prescribing was identified when concomitant medications were administered under the same GMS claim number.

RESULTS

Of 7,602 patients prescribed statins, co-prescribing of simvastatin, atorvastatin and fluvastatin with competing substrates or inhibitors of their metabolism occurred in 32, 26 and 13.4% of prescriptions issued. Thirty-four per cent of patients on simvastatin, 28% on atorvastatin and 16% on fluvastatin were prescribed medications with drug interaction potential.

CONCLUSION

Co-prescribing of statins with competing substrates or inhibitors of their metabolism occurred in up to one-third of prescriptions issued. When statins are co-prescribed with recognised inhibitors of drug metabolism, pravastatin, which does not undergo significant hepatic metabolism, is the statin of choice.

Do patient age and medical condition influence medical advice to stop smoking?

OBJECTIVE

to determine whether the age and medical condition of a patient influences hospital-based doctors' decision making when advising patients to stop smoking cigarettes.

METHODS

we presented 142 doctors from four grades (consultant, registrar, senior house officer and house officer) and four specialities (medicine, surgery, psychiatry and anaesthetics), based in a Dublin teaching hospital, with 20 clinical vignettes. Each vignette described a patient from one of five age groups with one of four levels of health. The vignettes were randomly mixed. We asked doctors to say whether they would advise the patient in each case to quit smoking.

RESULTS

hospital-based doctors are significantly less likely to advise patients aged over 65 years than younger patients of the hazards of cigarette smoking, irrespective of the person's physical or mental health (P < 0.001).

CONCLUSION

the advice given to patients about their cigarette smoking habits by hospital doctors is strongly influenced not only by the patient's health, but also by the patient's chronological age.

Typical Friedreich's ataxia without GAA expansions and GAA expansion without typical Friedreich's ataxia

We clinically assessed and performed polymerase chain reaction analysis for the GAA trinucleotide repeat expansion in 103 patients from 73 families in Ireland, with a prior clinical diagnosis of Friedreich's ataxia (FA) or an unclassified progressive ataxic syndrome. The patients were classified as "typical" or "atypical" FA according to Harding's mandatory clinical diagnostic criteria. All patients underwent blood glucose analysis, and electrocardiography and echocardiography was performed in 99 and 101 patients, respectively. Mutation screening for expanded CAG trinucleotide repeats, associated with spinocerebellar ataxia (SCA) 1, 2, 3 and 6 was performed in 86 patients overall, including all GAA negative patients. Forty-nine of 56 typical patients and 13 of 47 atypical patients were either homozygous or heterozygous for the GAA expansion. Seven patients with a typical FA phenotype were negative for the GAA expansion. Although one of these patients had vitamin E deficiency, and two had raised alpha-fetoprotein levels, three other GAA negative patients with a typical FA phenotype had no other identifiable cause for their ataxia, once again raising the possibility of locus heterogeneity in FA. It is also possible that these patients have two point mutations in the X25 gene, or that they have another ataxic syndrome mimicking the FA phenotype. Two families who were homozygous for the GAA expansion exhibited intrafamilial phenotypic variability. Only one GAA negative patient had the SCA 3 mutation, and this was the only patient in the study with a possible autosomal dominant inheritance pattern. In the homozygous GAA population typical patients had significantly more repeats on the smaller allele than atypical patients, and there was an inverse relationship between the number of repeats on the smaller allele and the age at presentation. There was also an inverse relationship between the repeat size on both the larger and the smaller of the two alleles and the age at becoming wheelchair bound. There was no significant relationship between repeat size and the other indices of disease severity, including the presence or absence of diabetes or cardiomyopathy. This is the first large study of an Irish population with progressive ataxia that has shown a similar phenotype/genotype relationship to studies of FA in other European and non-European populations. The relatively low sensitivity and specificity of Harding's clinical diagnostic criteria must be appreciated when clinically assessing patients with a progressive ataxic syndrome. Although molecular genetic analysis now plays an essential role in diagnosis and classification, patients with a typical FA phenotype without any identifiable cause for their ataxia exist.

Fracture of the occipital condyle: the forgotten part of the neck

A case of occipital condylar fracture in a multiply injured and unconscious motorcyclist is reported. This injury was clinically unsuspected but found on the lowest cuts of head computed tomography. It is shown that this site is often inadequately imaged when scanning the head and neck in victims of trauma. The Anderson and Montesano classification of occipital condylar fracture is described. It is noted that types 1 and 2 are stable injuries but type 3 is potentially unstable. A retrospective analysis of 30 head computed tomography scans in trauma cases revealed that in only 16 were the occipital condyles adequately imaged. It is emphasised that vigilance is required to detect fractures of the occipital condyle and that it should be standard practice to include this area when performing computed tomography of the head in trauma victims.

Detecting nonlinearity in psychological data: techniques and applications

Modern graphical and computational techniques for detecting nonlinearity in psychological data sets are presented. These procedures allow researchers to determine the information complexity of temporal data, using physiological and psychological measurements, and to provide evidence for chaos in time series contaminated by measurement noise. Problems with noise reduction and appropriate experimental control, using surrogate time series, are discussed, and applications of the technology are illustrated, using response time, handwriting, and typing data sets. In an experimental application of appropriate nonlinear analysis procedures, the results of a time series prediction experiment confirm that some subjects are sensitive to chaos. In contrast to previous attempts demonstrating sensitivity to chaos, the experiment reported here employs surrogate series to control for linear stochastic aspects of the stimulus sequences, such as autocorrelation. Recommendations for the selection of appropriate software for performing nonlinear analyses are presented, including a comprehensive list of World-Wide Web sites offering such software.

Growth in use of statins after trials is not targeted to most appropriate patients

OBJECTIVE

To determine whether growth in the use of lipid-lowering drugs after publication of studies in the primary and secondary prevention of coronary heart disease is in the population in which benefit was established, particularly middle-aged men.

METHODS

We performed a series of pharmacoepidemiologic surveys of community prescribing in Ireland over 4 years.

RESULTS

Nationally, the use of lipid-lowering drugs (92% statins) increased approximately fourfold from 1994 to 1998. In the Eastern Health Board region, the number of monthly recipients increased from 447 in April 1994 to 3530 in March 1998. Although use increased steadily after publication of Scandinavian Simvastatin Survival Study (4S) and West of Scotland Coronary Prevention Study (WOSCOPS) in 1994 and 1995, respectively, this occurred to a greater extent in women. However, after the Cholesterol and Recurrent Events (CARE) study in 1996 and subsequent recommendations that targeted statin use, particularly in men from 35 to 69 years old, there was a relatively greater increase in that population but, at 2.3%, it was well short of the target population of 5.8%. More women than men older than 65 years are receiving statins. The 10-mg dosage (a fourth or half that used in studies) is the most frequently dispensed.

CONCLUSION

The use of statins, although rising rapidly, is below targets and was initially not directed at the population likely to benefit most or in the recommended dosage. Consequently, the benefits projected from clinical trials may not be seen in clinical practice.

Acupressure and prevention of nausea and vomiting during and after spinal anaesthesia for caesarean section

The efficacy of acupressure at the P6 point in the prevention of nausea and vomiting during and after Caesarean section was studied. A double-blind, randomized controlled study of acupressure vs placebo was designed. Ninety-four patients scheduled for Caesarean section were included. The anaesthetic technique and postoperative analgesia were standardized. The use of acupressure reduced the incidence of nausea or vomiting from 53% to 23% compared with placebo (95% confidence interval (CI) 0.34-0.25; P = 0.002) during the operation and from 66% to 36% compared with placebo (95% CI 0.34-0.19; P = 0.003) after the operation. Other variables were similar between the groups.

Drug interactions avoided-a useful indicator of good prescribing practice

AIMS

To develop an index of quality prescribing in general practice by investigating the incidence of potential drug interactions when medicines were coprescribed within the State supported General Medical Services (GMS) in Ireland.

METHODS

We determined an odds ratio (OR), as a measure of the relative risk of being exposed to a potential interaction, comparing the use of the H2-receptor antagonist, cimetidine, with that of the noninteracting agents ranitidine, famotidine and nizatidine in users and nonusers of warfarin, phenytoin and theophylline.

RESULTS AND CONCLUSIONS

In 86 510 prescriptions for the H2-receptor antagonists potentially interacting drugs were dispensed to 8188 (9%) patients in the Eastern Health Board Region of the GMS. We found that prescribers were significantly less likely to use cimetidine (OR = 0.20,95% CI 0. 17-0.21, P < 0.001) in those patients who were coprescribed warfarin, suggesting good prescribing practice within the GMS. Similarly there was preferential use of the noninteracting H2-receptor antagonists in patients receiving phenytoin or theophylline and the extent of this selective prescribing was in keeping with the rank order of severity of interaction with these drugs. This novel pharmacological index may be a sensitive marker of good prescribing practice.

Deficits in nerve growth factor release and tyrosine receptor kinase phosphorylation are associated with age-related impairment in long-term potentiation in the dentate gyrus

Previous findings have indicated that nerve growth factor may play a role in the expression of long-term potentiation in perforant path-granule cell synapses and that nerve growth factor treatment restores the ability of aged rats to sustain long-term potentiation. In this study, we have attempted to analyse the changes which occur in nerve growth factor release and tyrosine receptor kinase phosphorylation following tetanization in tissue prepared from dentate gyrus of young rats, as well as aged rats which did or did not sustain long-term potentiation. We report that KCl-stimulated nerve growth factor release was significantly increased in slices of the dentate gyrus or whole hippocampus, but not in synaptosomes prepared from the dentate gyrus. KCl-induced nerve growth factor release was also significantly enhanced in slices prepared from tetanized, compared with untetanized, tissue obtained from young rats and aged rats which sustained long-term potentiation; this response was absent in tissue prepared from aged rats which failed to sustain long-term potentiation, perhaps due to the enhanced basal nerve growth factor release observed in this tissue. Tetanization increased tyrosine receptor kinase phosphorylation in the dentate gyrus of young rats and aged rats which sustained long-term potentiation. In parallel with the changes in nerve growth factor release, tyrosine receptor kinase phosphorylation was markedly increased in untetanized tissue, which may contribute to the lack of effect in tetanized tissue prepared from aged rats which failed to sustain long-term potentiation. We observed that nerve growth factor concentration and tyrosine receptor kinase expression were decreased in aged, compared with young, rats. The data suggest that deficits in nerve growth factor release and subsequent signalling may contribute to age-related deficits in long-term potentiation.

Duration of orthodontic treatment involving orthognathic surgery

The purpose of this study was to analyze factors influencing the duration of treatment in a sample of patients treated by a combined orthodontic/orthognathic surgery approach. Presurgical and postsurgical treatment times were assessed for 315 patients processed through an orthognathic team over a 7-year period. The median total treatment duration for all patients was 21.9 months, the median presurgical duration was 15.4 months, and the median postsurgical duration was 5.9 months. Treatment involving extractions resulted in significantly increased presurgical and total treatment times. Treatments performed in the university clinic showed reduced presurgical duration and increased postsurgical duration compared to treatments carried out by specialists outside the university. Presurgical, postsurgical, and total treatment times were significantly reduced when the orthodontist had treated 10 or more patients during the period. An earlier regimen of orthodontic treatment did not appear to have a significant effect on treatment duration.

Long-term potentiation in dentate gyrus of the rat is inhibited by the phosphoinositide 3-kinase inhibitor, wortmannin

The pivotal role of inositol phospholipids in cell signalling has been placed centre-stage again with the recognition that phosphoinositide (PI) 3-kinase is implicated in several cellular processes. Stimulation of PI-3 kinase requires activation of the 85 kD regulatory subunit which relies on tyrosine phosphorylation, one consequence of which is activation of the 110 kD catalytic subunit. In this study, we have investigated the role of PI 3-kinase in the expression of long-term potentiation (LTP) in perforant path-granule cell synapses of the rat. We report that intracerebroventricular injection of wortmannin inhibited expression of LTP, though it did not affect the early change in the synaptic response. Activation of PI 3-kinase was enhanced in tetanized tissue prepared from dentate gyrus, compared with untetanized tissue, but this effect was inhibited in tissue prepared from wortmannin-pretreated rats. LTP was associated with increased glutamate release, as previously described, but this effect was also inhibited in tissue prepared from wortmannin-pretreated rats. The results presented demonstrate that wortmannin also exerted an inhibitory effect on KCl-stimulated glutamate release and calcium influx in hippocampal synaptosomes in vitro. The evidence presented is consistent with the hypothesis that PI 3-kinase activation, possibly by NGF, plays a role in expression of LTP in dentate gyrus.

The management of dysphasia in skeletal hyperostosis

Diffuse idiopathic skeletal hyperostosis (DISH), or Forestier's disease, is an ossifying condition frequently encountered in otolaryngology as it affects 12-28 per cent of the adult population. This form of hyperostosis can manifest clinically with dysphagia, food impaction, hoarseness, stridor, myelopathies and other neurological problems. Judicious management of severe dysphagia proves challenging. The failure of conservative care often leaves surgery as the only option. In this report an anterolateral transcervical surgical approach to the confluent osteophytes is discussed and the value of videofluoroscopic swallow highlighted.