Low molecular weight heparins: a guide to their optimum use in pregnancy

The incidence of pulmonary embolism (PE) and venous thromboembolism (VTE) is higher in pregnant patients than in non-pregnant patients. The incidence of thrombosis in all pregnancies is reported to be between 0.05 and 1%, and an incidence as high as 3% may be present in women after caesarean section. Anticoagulant medication is prescribed during pregnancy in patients presenting with VTE, thrombophilia abnormalities, or a history of PE or VTE. Since unfractionated heparin (UH) does not cross the placental barrier, it has become the gold standard anticoagulant therapy during pregnancy. Oral anticoagulants may also be prescribed during the second trimester but they cross the placental barrier. Low molecular weight heparins (LMWH) are effective, easy to use and have good safety profiles. The practical conditions of use have yet to be validated for pregnancy settings. In the absence of an approved indication, LMWH use during pregnancy is therefore the responsibility of the practitioner. However, several studies on LMWH as prophylaxis for PE or VTE have shown that such products are effective with good safety. Moreover, LMWH use is associated with reduced frequencies of thrombocytopenia and osteoporosis compared with UH use. Very few studies on LMWH use for the treatment of PE or VTE during pregnancy have been published, but the safety of LMWH use in this setting appears to be good. The review of the use of LMWH in pregnancy settings includes recommendations on the practical conditions of use. In the absence of large-scale, randomised, double-blind trials in such settings (which are needed), we propose the use of LMWH as prophylaxis for PE and VTE during pregnancy, but not for the treatment of these conditions. In prophylaxis settings, dalteparin sodium and enoxaparin sodium have been the most widely studied LMWH and we believe that priority should therefore be given to those products. Pending approval of LMWH for use in pregnancy, the use of LMWH off-label is the practitioner's responsibility.     

Analysis of customized corneal ablations: theoretical limitations of increasing negative asphericity

PURPOSE: To determine the ablation depths of customized myopic excimer laser photoablations performed to change corneal asphericity after laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). METHODS: A mathematical model of aspheric myopic corneal laser surgery was generated. The initial corneal surface was modeled as a conic section of apical radius R(1) and asphericity Q(1). The final corneal surface was modeled as a conic section of apical R(2) and asphericity Q(2), where R(2) was calculated from the paraxial optical formula for a given treatment magnitude (D), and Q(2) was the intended final asphericity. The aspheric profile of ablation was defined as the difference between the initial and final corneal profiles for a given optical zone diameter (S), and the maximal depth of ablation was calculated from these equations. Using the Taylor series expansion, an equation was derived that allowed the approximation of the central depth of ablation (t(0)) for various magnitudes of treatment, optical zone diameters, and asphericity. In addition to the Munnerlyn term (M), incorporating Munnerlyn's approximation (-D small middle dot S(2)/3), the equation included an asphericity term (A) and a change of asphericity term (Delta). This formula (t(0) = M + A + Delta) was used to predict the maximal depth of ablation and the limits of customized asphericity treatments in several theoretical situations. RESULTS: When the initial and final asphericities were identical (no intended change in asphericity; Q(1) = Q(2); Delta = 0), the maximal depth of ablation (t(0) = M + A) increased linearly with the asphericity Q(1). To achieve a more prolate final asphericity (Q(2) < Q(1); dQ < 0; Delta > 0), the maximal depth of ablation (M + A + Delta) was increased. For treatments in which Q(2) was intended to be more oblate than Q(1) (Q(2) > Q(1); dQ > 0; Delta < 0), the maximal depth of ablation was reduced. These effects sharply increased with increasing diameters of the optical zone(s). Similarly, in the case of PRK, the differential increase in epithelial thickness in the center of the cornea compared with the periphery resulted in increased oblateness. CONCLUSIONS: Aspheric profiles of ablation result in varying central depths of ablation. Oblateness of the initial corneal surface, intentional increase in negative asphericity, and enlargement of the optical zone diameter result in deeper central ablations. This may be of clinical importance in planning aspheric profiles of ablation in LASIK procedures to correct spherical aberration without compromising the mechanical integrity of the cornea.     

Cancer incidence and high environmental arsenic concentrations in rural populations: Results of an ecological study

A number of ecological studies have suggested associations between arsenic in drinking water and increased rates of some cancers. To investigate associations in areas with high environmental arsenic concentrations, geographical areas with surface soil inorganic arsenic concentrations of >100 mg/kg and/ or drinking water arsenic concentrations >0.01 mg/l were selected and the relationship with cancer incidence explored. Standardised incidence rates (SIRs) for cancer were generated for 22 areas between 1982 and 1991 using Victorian Cancer Registry data and Victorian cancer rates as a baseline. SIRs were also generated for combined areas according to environmental exposure type, i.e. whether an area had high soil and/or high water arsenic concentrations. The SIRs for both males and females for the combined 22 areas were increased for all cancers 1.06 (95% confidence interval, CI; 1.03-1.09), prostate cancer 1.14 (1.05-1.23), kidney cancer 1.16 (0.98-1.37), melanoma 1.36 (1.24-1.48), chronic myeloid leukemia 1.54 (1.13-2.10) and breast cancer in females 1.10 (1.03-1.18). When stratifying into exposure categories, the SIR for prostate cancer was significant at 1.20 (1.06-1.36) for the high soil/high water category only. No significant dose- response relationship between drinking water and individual cancers was observed. Of the a priori cancers associated with environmental arsenic exposure, only prostate cancer incidence was significantly elevated in this study. This result was likely confounded by a number of factors and was limited by low power and exposure misclassification.     

Paternal deletion of the GNAS imprinted locus (including Gnasxl) in two girls presenting with severe pre- and post-natal growth retardation and intractable feeding difficulties

Deletions of the long arm of chromosome 20 are rare. Here, we report on two girls with a very small interstitial deletion of the long arm of chromosome 20 presenting with severe pre- and post-natal growth retardation, intractable feeding difficulties, abnormal subcutaneous adipose tissue, similar facial dysmorphism, psychomotor retardation and hypotonia. Standard cytogenetic studies were normal, but high-resolution chromosomes analysis showed the presence of a chromosome (20)(q13.2-q13.3) interstitial deletion. Karyotypes of both parents were normal. Molecular studies using FISH and microsatellite polymorphic markers showed that the deletion was of paternal origin and was approximatively 4.5 Mb in size. A review of other reported patients with similar deletions of the long arm of chromosome 20 shows that the observed phenotype might be explained in the light of the GNAS imprinted locus in particular by the absence of the Gnasxl paternally imprinted gene and the TFA2PC gene in the deleted genetic interval.     

Time of day effects on isometric and isokinetic torque developed during elbow flexion in humans

 The aim of this study was, firstly, to confirm or refute the existence of circadian rhythms during several velocities of concentric action of the elbow flexor muscles and, secondly, to compare the characteristics of these circadian rhythms with those obtained during isometric actions. Eight volunteer subjects participated in this study. The circadian rhythms were obtained from six test sessions (TS) carried out at different times of day over 6 days with only one TS a day. During each TS, oral temperature and the torque of the muscle action were measured. The subjects made, on an isokinetic ergometer, two maximal isokinetic concentric elbow flexions at five angular velocities (60, 120, 180, 240 and 300° · s⁻¹) and at an angle of 60°. Torque-angular velocity relationships, which characterised the functioning of the muscle during concentric and isometric actions, were established for the different times of day. The values of the torque recorded at each of the angular velocities presented a clear circadian rhythm. After normalisation of the torque values, no significant differences were observed among the computed characteristics of the circadian rhythms obtained at different angular velocities. Since the circadian rhythms during isometric and concentric torque were the same, the characteristics of the circadian rhythms of the musculo-skeletal system can be studied using either type of muscle action. The results indicated that torque and temperature varied concomitantly during the day. Thus, the recording of body temperature allows one to estimate the times of occurrence of maximal and minimal values in the circadian rhythm of muscle torque. Accepted: 10 October 2000     

Gene mutation and V(D)J recombination in the radiosensitive irs lines

lines irs1, irs2 and irs3, derived from V79-4 hamster cells,are sensitive to DNA-damaging agents including ionizing radiations.However, unlike some other radiosensitive lines, the irs linesshow no apparent defect in the repair of DNA strand breaks.We have now assessed the mis-repair of DNA damage in the irslines by measuring spontaneous and X-ray induced frequenciesof mutation in the HPRT gene, irsl was found to be hypermutable,showing instability in spontaneous mutant frequency and an elevationof the radiation-induced frequency relative to the parentalline. In contrast, irs2 and irs3 showed similar mutational responsesto the parental line. The results support other lines of evidencesuggesting that irs1 has a mis-repair phenotype. The irs2 linehas previously been shown to have a phenotype similar to cellsfrom the human disorder ataxia-telangiectasia and this similarityis maintained in their mutational response to X-rays. The irslines were also tested for ability to undergo V(D)J recombination,since this process has recently been found to be defective insome radiosensitive lines with impaired double-strand breakrepair. Using an extrachromosomal vector containing a V(D)Jrearrangement cassette, correct recombination was shown to occurat similar frequencies to parental V79-4 cells in each of thethree irs lines. Thus the irs lines indicate that processesother than DNA double-strand break repair also control radiosensitivity,in particular those processes which may affect the regulationof DNA repair.     

Up-regulated expression of ADAM17 in human colon carcinoma: co-expression with EGFR in neoplastic and endothelial cells

The ADAM17 metalloproteinase (a disintegrin and metalloprotease 17) controls epidermal growth factor receptor (EGFR) activation through regulated shedding of EGFR ligands. With the advent of new therapeutic options targeting EGFR signalling in colon carcinoma, it was decided to determine ADAM17 status in relation to clinico-pathological parameters and EGFR status. To this end, a series of 39 colon carcinomas were analysed. Immunohistochemistry and immunofluorescence were used to localize ADAM17, EGFR, and the activated forms of EGFR. The activated form of ADAM17 was assessed in primary cancers and colon cell lines by immunoblotting. ADAM17 and EGFR mRNA levels were assessed by quantitative RT-PCR. Chromogenic in situ hybridization (CISH) was used to quantify the HER1 gene. ADAM17 was strongly expressed in all tumours, by both neoplastic and endothelial cells. It was expressed both as a pro- and as an active form in tumours and colonic cancer cell lines. ADAM17 mRNA was up-regulated in 90% of colon carcinomas relative to the paired normal mucosa, whatever the tumour grade or stage. When present, activated EGFR was co-expressed with ADAM17 by colon carcinomas, although at a variable level among tumour cells, and by endothelial cells. EGFR mRNA was overexpressed in 77% of colon carcinomas compared with the paired normal mucosa. One case showed high-level amplification of HER1. In conclusion, this study is the first demonstration that ADAM17 is overexpressed in human primary colon carcinoma, whatever the tumour stage and differentiation and whatever the level of EGFR expression. Its co-expression with EGFR, in both neoplastic and endothelial cells, suggests a role for ADAM17 in tumour growth and angiogenesis.     

Detection and verification of Mycobacterium avium subsp. paratuberculosis in fresh ileocolonic mucosal biopsy specimens from individuals with and without Crohn's disease

Mycobacterium avium subsp. paratuberculosis is a robust and phenotypically versatile pathogen which causes chronic inflammation of the intestine in many species, including primates. M. avium subsp. paratuberculosis infection is widespread in domestic livestock and is present in retail pasteurized cows' milk in the United Kingdom and, potentially, elsewhere. Water supplies are also at risk. The involvement of M. avium subsp. paratuberculosis in Crohn's disease (CD) in humans has been uncertain because of the substantial difficulties in detecting this pathogen. In its Ziehl-Neelsen staining-negative form, M. avium subsp. paratuberculosis is highly resistant to chemical and enzymatic lysis. The present study describes the development of optimized sample processing and DNA extraction procedures with fresh human intestinal mucosal biopsy specimens which ensure access to M. avium subsp. paratuberculosis DNA and maximize detection of these low-abundance pathogens. Also described are two nested PCR methodologies targeted at IS900, designated IS900[L/AV] and IS900[TJ1-4], which are uniquely specific for IS900. Detection of M. avium subsp. paratuberculosis in mucosal biopsy specimens was also evaluated by using mycobacterial growth indicator tube (MGIT) cultures (Becton Dickinson). IS900[L/AV] PCR detected M. avium subsp. paratuberculosis in 34 of 37 (92%) patients with CD and in 9 of 34 (26%) controls without CD (noninflammatory bowel disease [nIBD] controls) (P = 0.0002; odds ratio = 3.47). M. avium subsp. paratuberculosis was detected by IS900[L/AV] PCR in MGIT cultures after 14 to 88 weeks of incubation in 14 of 33 (42%) CD patients and 3 of 33 (9%) nIBD controls (P = 0.0019; odds ratio = 4.66). Nine of 15 (60%) MGIT cultures of specimens from CD patients incubated for more than 38 weeks were positive for M. avium subsp. paratuberculosis. In each case the identity of IS900 from M. avium subsp. paratuberculosis was verified by amplicon sequencing. The rate of detection of M. avium subsp. paratuberculosis in individuals with CD is highly significant and implicates this chronic enteric pathogen in disease causation.     

T-cell-stimulating protein A elicits immune responses during meningococcal carriage and human disease

In recognition of the need for immunological memory-inducing components for future Neisseria meningitidis group B vaccines, we previously searched the proteome of N. meningitidis and identified T-cell-stimulating protein A (TspA). This study was designed to confirm the immunogencity of TspA and to examine the subset of T-helper cell responses to the protein in patients and nasopharyngeal carriers. The tspA gene was reconstructed, cloned, and expressed in Escherichia coli, and the recombinant TspA (rTspA) protein was affinity purified. T-cell proliferative responses to rTspA were detected in the peripheral blood mononuclear cells (PBMCs) of convalescent patients and carriers, confirming that TspA-specific T-cell responses were stimulated by invasive disease and nasopharyngeal colonization. Following stimulation of PBMCs with meningococcal lysate, increased frequencies of both Th1 and Th2 cells were observed, indicating that, as during carriage, invasive meningococcal disease induced an unbiased T-helper subset response. A similar unbiased T-helper response was also detected against rTspA in the PBMCs of convalescent patients. The response of PBMCs from the carriers to TspA stimulation, however, was very weak, and the frequencies of cytokine-positive CD4 cells were not significantly greater than the frequencies in unstimulated control cultures. All of the patients and carriers responded with serum antimeningococcal immunoglobulin G (IgG) antibodies, while four of six samples from patients and 5 of 14 samples from carriers contained detectable anti-rTspA IgG antibodies. Taken together, the results of this study confirmed the immunogenicity of TspA in humans during natural meningococcal infection, and therefore, TspA is worthy of further investigation as a possible T-cell stimulating component of future vaccines.     

The 3111 Clock gene polymorphism is not associated with sleep and circadian rhythmicity in phenotypically characterized human subjects

Mutations in clock genes are associated with abnormal circadian parameters, including sleep. An association has been reported previously between a polymorphism (3111C), situated in the 3'-untranslated region (3'-UTR) of the circadian gene Clock and evening preference. In the present study, this polymorphism was assessed in: (1) 105 control subjects with defined diurnal preference, (2) 26 blind subjects with free-running circadian rhythms and characterized with regard to circadian period (tau) and (3) 16 delayed sleep phase syndrome patients. The control group was chosen from a larger population (n = 484) by Horne-Ostberg questionnaire analysis, from which three subgroups were selected (evening, intermediate and morning preference). Data from sleep diaries completed by 90% of these subjects showed a strong correlation between preferred and estimated timings of sleep and wake. The mean timings of activities for the evening group were at least 2 h later than the morning group. Genetic analysis showed that, in contrast with the previously published finding, there was no association between 3111C and eveningness. Neither was there an association between 3111C and tau, nor a significant difference in 3111C frequency between the normal and delayed sleep phase syndrome groups. To assess the effect of this polymorphism on messenger RNA (mRNA) translatability, luciferase reporter gene constructs containing the two Clock polymorphic variants in their 3'-UTR were transfected into COS-1 cells and luciferase activity measured. No significant difference was observed between the two variants. These results do not support Clock 3111C as a marker for diurnal preference, tau, or delayed sleep phase syndrome in humans.