Mutation analysis in 57 unrelated patients with MPS II (Hunter's disease)

Genomic DNA from 57 unrelated MPS II (Hunter's disease) patients was analysed for mutations of the iduronate sulphatase (IDS) gene. The aim of the study was threefold: to identify the primary genetic lesion in patients, to investigate the correlation between genotype and phenotype, and most importantly, to provide reliable carrier testing for female members once the family mutation was identified. In 42 patients, point mutations were identified involving single base substitutions, deletions, or insertions. These included four new nonsense mutations (R8X, C84X, E245X, Y466X), six new missense mutations (D45N, N115Y, P228L, P266R, E434K, I485K, W502C), three new insertions (c70C71ins, c652C654ins, c709G710ins), six new deletions (c500delC, c705delC, c1023delA, c1049delA, c1141delC, c1576delG), and five new mutations involving splice sites (IVS1-2 a-->g, IVS2-10 t-->g, IVS5 + 2 t-->g L236L, IVS7 + 2 t-->c). One patient had a new seven base deletion in exon 9 (c1482-1488del). Four patients were shown to have complete deletions of the IDS gene and two deletions involved one or more exons. Previously described mutations present in these patients were Q80X, P86L, R172X, G374G, S333L, R443X, and R468Q. In eight patients, no mutation was detected throughout the entire coding region. Most mutations that result in MPS II appear to be unique. Absence of the probands' mutations in eight of nine maternal grandmothers suggests many mutations have arisen recently. Prediction of the clinical phenotype from the identified genotype was difficult in some families, and further studies using reverse transcription polymerase chain reaction are needed to confirm the predicted effects on the IDS mRNA suggested by genomic analysis.

Effect of lithium gamma-linolenate on the growth of experimental human pancreatic carcinoma

BACKGROUND

The lithium salt of gamma-linolenic acid (Li-GLA) is growth inhibitory to pancreatic cancer cells in vitro and is reported to prolong the survival of patients with pancreatic cancer. The effect of Li-GLA on the growth of human pancreatic carcinoma in vivo is not known. In this study the effect of parenterally administered Li-GLA on the growth of human pancreatic carcinoma in nude mice was tested.

METHODS

Pancreatic tumours were produced in nude mice by subcutaneous implantation of MIA PaCa-2 cells. This cell line is sensitive to Li-GLA in vitro. Mice were randomly treated with intraperitoneal, intravenous or intratumoral Li-GLA. Each group also had controls.

RESULTS

Both intravenous and intraperitoneal administration of Li-GLA had no significant effect on tumour growth or tumour phospholipid fatty acid composition. Intratumoral administration of Li-GLA was, however, associated with a significant antitumour effect.

CONCLUSION

Within the limitations of this tumour model, the benefit seen with intravenous Li-GLA in patients with pancreatic carcinoma cannot be explained by tumour growth inhibition. Local administration appears to be more effective than intravenous or intraperitoneal therapy.

Pediatric ambulance utilization in a large American city: a systems analysis approach

BACKGROUND

Research on utilization of ambulances by pediatric patients lacks an objective, reproducible tool for the evaluation of patterns of ambulance use by both the providers and the users of this resource.

OBJECTIVES

1) To develop an objective, diagnosis-based measure of appropriateness of ambulance utilization. 2) To use the measure to evaluate whether Municipal Ambulance Service dispatchers assign ambulances appropriately, and whether parents/caretakers request ambulances appropriately.

STUDY DESIGN

1) Development of the pediatric ambulance need evaluation (PANE) tool: The consensus of an expert panel was used to assign patients arriving by ambulance to three levels of prehospital transport need based upon their ultimate hospital discharge diagnoses, and were as follows: required advanced life support ambulance (ALS); required basic life support ambulance (BLS); required a less acute mode of transport (LAT). 2) Assessment of appropriateness of ambulance assignments by EMS call-receiving operators (CRO) and of ambulance requests by parents/caretakers: Comparison of actual type of ambulance assigned and of need for ambulance, using the PANE tool and hospital admission rates as gold standards.

DATA COLLECTION

Level of prehospital transport provided (ALS vs BLS), ultimate ED diagnosis, and ED disposition (admission vs discharge) was collected for each patient from information abstracted from the prehospital and ED records.

SETTING

Bellevue Hospital Center and Harlem Hospital Center, two level I trauma centers in New York City, both with Pediatric Emergency Departments staffed 24 hours a day by attending physicians and residents.

PATIENT SELECTION

Consecutive sample of 2633 patients, birth to 18 years of age, who arrived to either hospital by ambulance as primary transports from the field over a one-year period.

RESULTS

1) Development of PANE tool: At Bellevue Hospital, 7% of ED visits arrived by ambulance; at Harlem Hospital, 5% arrived by ambulance. Using these ambulance arrivals, 215 diagnoses were identified for inclusion in the PANE tool. An expert panel categorized each diagnosis as requiring ALS, BLS, or LAT, with a high level of interobserver agreement (weighted kappa = 0.793). As a measure of external validity of the PANE, admission rates were highest in the ALS group, next highest in the BLS group, and lowest in the LAT group (chi2 for trend, P < 0.05). 2) Assessment of ambulance assignments and requests: According to the PANE tool, the sensitivity of dispatcher assignment of ALS ambulances was 72 %. Therefore, 28 % of patients who required an ALS ambulance received BLS care. 50% of patients assigned to an ALS ambulance did not require that level of care, and 1/3 of these were categorized by the PANE as not requiring an ambulance at all.

CONCLUSIONS

The PANE tool compared favorably to admission rates as a measure of the severity of illness of patients arriving by ambulance. Applying the PANE tool, we conclude that the majority of requests for ambulances are appropriate, and that the majority of the time dispatchers were able to dispatch the appropriate level of care. However, there is room for significant improvement in utilization of ambulances, and tools like the PANE will be useful in achieving this goal.

Preventing hypothermia: convective and intravenous fluid warming versus convective warming alone

STUDY OBJECTIVE

To test the hypothesis that warming intravenous (i.v.) fluids in conjunction with convective warming results in less intraoperative hypothermia (core temperature < 36.0 degrees C) than that seen with convective warming alone.

DESIGN

Prospective, randomized study.

SETTING

University affiliated tertiary care teaching hospital.

PATIENTS

61 ASA physical status, I, II, and III adults undergoing major surgery and general anesthesia with isoflurane.

INTERVENTIONS

All patients received convective warming. Group 1 patients received warmed fluids (setpoint 42 degrees C). Group 2 patients received room temperature fluids (approximately 21 degrees C).

MEASUREMENTS AND MAIN RESULTS

Lowest and final intraoperative distal esophageal temperatures were higher (p < 0.05) in Group 1 (mean +/- SEM: 35.8 +/- 0.1 degrees C and 36.6 +/- 0.1 degrees C) versus Group 2 (35.4 +/- 0.1 degrees C and 36.1 +/- 0.1 degrees C, respectively). Compared with Group 1, more Group 2 patients were hypothermic at the end of anesthesia (10 of 26 patients, or 38.5% vs. 4 of 30 patients, or 13%; p < 0.05). After 30 minutes in the recovery room, there were no differences in temperature between groups (36.7 +/- 0.1 degrees C and 36.5 +/- 0.1 degrees C in Groups 1 and 2, respectively). Intraoperative cessation of convective warming because of core temperature greater than 37 degrees C was required in 33% of Group 1 patients (vs. 11.5% in Group 2; p = 0.052).

CONCLUSIONS

The combination of convective and fluid warming was associated with a decreased likelihood of patients leaving the operating room hypothermic. However, average final temperatures were greater than 36 degrees C in both groups, and intergroup differences were small. Care must be taken to avoid overheating the patient when both warming modalities are employed together.

Cloning and characterization of a cDNA encoding murine coagulation factor X

The cDNA encoding murine coagulation factor X (fX) was isolated and reconstructed from a lambdaZap cDNA library generated from murine liver mRNA. The cDNA contains 1486 bases starting at the 5'-translation initiation codon. It includes an open reading frame of 1443 nucleotides, followed by an 18 residue 3' nontranslated sequence downstream of the first stop codon. and a 3' poly(A) tail. The translation product is composed of a 40-amino acid signal/propeptide region followed by a 441-residue mature protein. The latter is highly homologous to that of human and rat fX. All protein domains of human and rat fX are strictly conserved in mouse fX. The cDNA coding for mouse fX has been expressed in human embryonic kidney 293 cells and generates fX activity measured in a clotting assay using human fX-deficient plasma.

Discovery of critical Tol A-binding residues in the bactericidal toxin colicin N: a biophysical approach

Colicins translocate across the Escherichia coli outer membrane and periplasm by interacting with several receptors. After first binding to outer membrane surface receptors via their central region, they interact with TolA or TonB proteins via their N-terminal regions. Finally, the toxic C-terminal region is inserted into or across the cytoplasmic membrane. We have measured the binding of colicin N to TolA by isothermal titration microcalorimetry (ITC) and tryptophan fluorescence. The isolated N-terminal domain exhibits a higher affinity for TolA (Kd = 1 microM) than does the whole colicin (18 microM), and similar behaviour has been observed when the N-terminal domain of the g3p protein of the bacteriophage fd, which also binds TolA, is examined in isolation and in situ. This may indicate a similar mechanism in which a cryptic TolA binding site is revealed after primary receptor binding. The isolated colicin N N-terminal domain appears to be unstructured in circular dichroism and fluorescence studies. We have used mutagenesis and ITC to characterize the TolA binding site and have shown it to be of a different sequence and much further from the N-terminus than previously thought.

Generalized linear least squares method for fast generation of myocardial blood flow parametric images with N-13 ammonia PET

In this paper, we developed and tested strategies for estimating myocardial blood flow (MBF) and generating MBF parametric images using positron emission tomography (PET), N-13 ammonia, and the generalized linear least square (GLLS) method. GLLS was generalized to the general linear compartment model, modified for the correction of spillover, validated using simulated N-13 ammonia data, and examined using PET data from several patient studies. In comparison to the standard model-fitting procedure, the GLLS method provided similar accuracy and superior computational speed.

Differential effects of cryopreservation on nuclear or cytoplasmic maturation in vitro in immature mouse oocytes from stimulated ovaries

The aim of this study was to develop a maturation protocol for immature oocytes and assess the protocol with cryopreserved oocytes. Nuclear maturation (mature spindle and aligned chromosomes) occurred irrespective of the treatment regime: 71-89% of oocytes matured in vitro had a normal spindle and chromosomes compared with 87% matured in vivo. Fertilization rates were not significantly different from those of in-vivo matured oocytes. Of the maturation treatment regimes investigated, the initial treatment producing best development to blastocyst (cytoplasmic maturation) involved a 2 h incubation in standard maturation medium (SMM) containing 7.5 IU follicle stimulating hormone (FSH) followed by 14 h in SMM plus 7.5 IU FSH:luteinizing hormone with follicular cells [62% (range 49-69)]. The addition of 1 ng/ml epidermal growth factor (EGF) in this protocol resulted in development [75% (range 71-81)] that was not significantly different from in-vivo matured oocytes [82% (range 73-90)]. Exposure of the oocytes to 1.5 M dimethylsulphoxide (DMSO) did not affect fertilization or development rates. Following a slow-cool/thaw freezing regime, 81% (range 74-89) of the oocytes were morphologically normal, i.e. had a spherical shape with an intact zona and oolemma; they had, however, lost their previously attached cumulus and corona cells. Maturation of frozen-thawed oocytes in the presence of EGF gave good fertilization rates but poor development rates [80% (range 77-86) and 37% (range 33-40) respectively]. In conclusion, the best maturation, both nuclear and cytoplasmic, occurred in the presence of a combination of gonadotrophins, EGF and follicular cells. Oocytes cryopreserved using a slow-cool/thaw regime can be matured to produce blastocysts after in-vitro fertilization.

A survey of audit activity in general practice

BACKGROUND

Since 1991, all general practices have been encouraged to undertake clinical audit. Audit groups report that participation is high, and some local surveys have been undertaken, but no detailed national survey has been reported.

AIM

To determine audit activities in general practices and the perceptions of general practitioners (GPs) regarding the future of clinical audit in primary care.

METHOD

A questionnaire on audit activities was sent to 707 practices from 18 medical audit advisory group areas. The audit groups had been ranked by annual funding from 1992 to 1995. Six groups were selected at random from the top, middle, and lowest thirds of this rank order.

RESULTS

A total of 428 (60.5%) usable responses were received. Overall, 346 (85%) responders reported 125.7 audits from the previous year with a median of three audits per practice. There was no correlation between the number of audits reported and the funding per GP for the medical audit advisory group. Of 997 audits described in detail, changes were reported as 'not needed' in 220 (22%), 'not made' in 142 (14%), 'made' in 439 (44%), and 'made and remeasured' in 196 (20%). Thus, 635 (64%) audits were reported to have led to changes. Some 853 (81%) of the topics identified were on clinical care. Responders made 242 (42%) positive comments on the future of clinical audit in primary care, and 152 (26%) negative views were recorded.

CONCLUSION

The level of audit activity in general practice is reasonably high, and most of the audits result in change. The number of audits per practice seems to be independent of the level of funding that the medical audit advisory group has received. Although there is room for improvement in the levels of effective audit activity in general practice, continued support by the professionally led audit groups could enable all practices to undertake effective audit that leads to improvement in patient care.

New uses for old DNA

Several years have elapsed since the last report of million-year-old DNA, coinciding with increased standards for experimental procedures in ancient DNA research. Whereas many earlier studies are now regarded as erroneous, the recent successful characterisation of Neanderthal DNA has set new standards for the field. Researchers continue to find new ways to exploit preserved genetic information in studies of more recent remains, widening the utility of ancient DNA.

A common mitochondrial DNA variant is associated with insulin resistance in adult life

Mitochondrial DNA is maternally inherited. Mitochondrial DNA mutations could contribute to the excess of maternal over paternal inheritance of non-insulin-dependent diabetes mellitus (NIDDM). We therefore investigated the relationship between this variant, insulin resistance and other risk factors in a cohort which had been well characterised with respect to diabetes. Blood DNA was screened from 251 men born in Hertfordshire 1920-1930 in whom an earlier cohort study had shown that glucose tolerance was inversely related to birthweight. The 16189 variant (T--> C transition) in the first hypervariable region of mitochondrial DNA was detected using the polymerase chain reaction and restriction digestion. DNA analysis showed that 28 of the 251 men (11%) had the 16189 variant. The prevalence of the 16189 variant increased progressively with fasting insulin concentration (p < 0.01). The association was independent of age and body mass index and was present after exclusion of the patients with NIDDM or impaired glucose tolerance. We found that insulin resistance in adult life was associated with the 16189 variant. This study provides the first evidence that a frequent mitochondrial variant may contribute to the phenotype in patients with a common multifactorial disorder.

Growth inhibitory effect of lithium gammalinolenate on pancreatic cancer cell lines: the influence of albumin and iron

Essential fatty acids, especially gamma linolenic (GLA) and eicosapentaenoic acids, have been proposed as potential anticancer drugs. Our aim was to study the effect of the lithium salt of gamma linolenic acid (LiGLA) on the growth of two human pancreatic cancer cell lines (MIA PaCa2 and Panc 1) and primary human fibroblasts (HFF 5) in vitro. Cell growth was assessed by a microculture tetrazolium (MTT) assay. LiGLA had a selective growth inhibitory effect on pancreatic cancer cell lines with 50% growth inhibition (IC50) at approximately 6-16 mumol/l compared with approximately 111 mumol/l for the fibroblasts. The degree of growth inhibition increased with the time of exposure to LiGLA. Special attention was paid to the influence of albumin and iron on LiGLA-mediated growth inhibition. Albumin incorporated into essentially serum-free culture medium inhibited the effect of LiGLA in a dose-dependent manner, associated with reduced GLA uptake by cancer cells. Ferric ions were confirmed as potentiators of the growth inhibitory effect of LiGLA but more physiologically relevant transferrin-bound iron was ineffective. With further improvements in the fatty acid delivery mechanism, LiGLA may become a useful adjunct in the management of pancreatic cancer patients.

The Ov20 protein of the parasitic nematode Onchocerca volvulus. A structurally novel class of small helix-rich retinol-binding proteins

Ov20 is a major antigen of the parasitic nematode Onchocerca volvulus, the causative agent of river blindness in humans, and the protein is secreted into the tissue occupied by the parasite. DNA encoding Ov20 was isolated, and the protein was expressed in Escherichia coli. Fluorescence-based ligand binding assays show that the protein contains a high affinity binding site for retinol, fluorescent fatty acids (11-((5-dimethylaminonaphthalene-1-sulfonyl)amino)undecanoic acid, dansyl-DL-alpha-aminocaprylic acid, and parinaric acid) and, by competition, oleic and arachidonic acids, but not cholesterol. The fluorescence emission of dansylated fatty acids is significantly blue-shifted upon binding in comparison to similarly sized beta-sheet-rich mammalian retinol- and fatty acid-binding proteins. Secondary structure prediction algorithms indicate that a alpha-helix predominates in Ov20, possibly in a coiled coil motif, with no evidence of beta structures, and this was confirmed by circular dichroism. The protein is highly stable in solution, requiring temperatures in excess of 90 degrees C or high denaturant concentrations for unfolding. Ov20 therefore represents a novel class of small retinol-binding protein, which appears to be confined to nematodes. The retinol binding activity of Ov20 could possibly contribute to the eye defects associated with onchocerciasis and, because there is no counterpart in mammals, represents a strategic target for chemotherapy.

Endometrial effects of three doses of trimegestone, a new orally active progestogen, on the postmenopausal endometrium

OBJECTIVE

To study the effects of oral trimegestone on endometrial histology and vaginal bleeding when given in combination with oral 17-beta-oestradiol.

METHODS

This was a prospective, randomised, double-blind, parallel groups, pilot comparative study. Thirty-eight healthy postmenopausal women with normal endometrial histology were given oral 17-beta-oestradiol, 2 mg/day for three continuous cycles of 28 days, plus oral trimegestone, 0.10, 0.25 or 0.50 mg/day from day 15 to day 28 of each cycle. A Vabra biopsy was performed late in the oestradiol/trimegestone phase of cycle 3 and examined for histological evidence of secretory transformation of the endometrium. Characteristics of vaginal bleeding were recorded on a daily basis.

RESULTS

Thirty-seven women completed the study, of whom 31 yielded adequate tissue for histological assessment. All showed secretory transformation of the endometrium. Bleeding was of earlier onset and longer duration with the lowest dose of trimegestone.

CONCLUSIONS

Trimegestone is a highly effective oral progestogen for endometrial protection, all doses inducing secretory endometrial transformation. Although bleeding patterns suggest a weaker effect of the lowest dose used, the minimum effective dose for endometrial protection has still to be determined and may be lower than those used in this study.

Information delivery: the provision of written information for patients following coronary angiography and post-discharge management

To improve management of risk factors in patients diagnosed with significant coronary artery disease after day case angiography, we gave patients a discharge information sheet emphasising the importance of prognostic therapy, risk factors and follow-up. The sheet was evaluated in 40 patients. A nurse talked through the information sheet with the patients after their angiogram and helped to complete relevant sections. One group of patients was given a copy of the sheet to take home, while the second group remained a 'verbal information only' group. Providing written information resulted in improvements in follow-up regarding blood pressure and drug therapy checks, but there was no significant difference between the groups in the follow-up management of cholesterol or in patient awareness of their cholesterol level. Patients were not likely to remember the sheet, even though a nurse had talked them through it, unless it was backed up with a written copy which could be taken away. It became apparent that the vast majority of patients remembered a pictorial representation of the extent of their disease (routinely provided) in contrast to the relatively disappointing numbers (43%) who remembered the information sheet. To evaluate further the importance of content and style in effective information delivery, we are evaluating the combination of written information with a visual representation of the heart.

Novel mutations in Sanfilippo A syndrome: implications for enzyme function

Sanfilippo syndrome type A or mucopolysaccharidosis IIIA (MPS IIIA) is an autosomal recessive lysosomal storage disorder caused by the deficiency of sulfamidase. The resulting lysosomal storage of heparan sulfate may lead to severe neurodegeneration preceded by progressive dementia, often combined with aggressive and hyperactive behaviour. A total of 109 patients from four different geographic areas were screened for the common mutation R245H and two other previously identified mutations. SSCP analysis of exons was used to characterize the unknown alleles. We identified 16 novel sequence variants, 12 of them likely to be pathogenic. The majority of the pathogenic variants were single base pair changes leading to missense mutations. Several single base pair deletions/insertions and one nonsense mutation were also identified. Altogether, we were able to characterize 55% of the pathogenic alleles. Sequence homology between sulfamidase and N-acetylgalactosamine 4-sulfatase, the first sulfatase to have its tertiary structure defined, suggests that amino acid residues R74 and T79, which were found to be mutated, are likely to be involved in the formation of the active site of sulfamidase. R245H accounts for 31% of the Sanfilippo A alleles in Australasia, for 19.2% of the alleles in patients from the UK and has a high frequency of 57.8% in patients from The Netherlands. The identification of mutations common in certain geographic regions or ethnic groups will help in the diagnosis of MPS IIIA and allow carrier testing and improved genetic counselling.