A 1H-NMR thermometer suitable for cryoprobes

Most established NMR thermometers rely on temperature-dependent chemical shift differences measured from samples that are either neat or concentrated solutions (e.g. ethylene glycol, methanol). These are unsuitable for modern cryoprobes on account of strong radiation damping resulting from the high Q of the probe. Using perdeuterated methanol, we established a relationship between the chemical shift difference and temperature, and we show that this relationship is well fitted by a quadratic equation. The actual temperature within a sample tube in the probe was verified using a Pt-100 resistor.

Sudden infant death syndrome: No increased risk after immunisation

BACKGROUND

Although previous studies have shown either no association between immunisation and SIDS or even a decreased risk of SIDS, adverse effects, including death, from immunisations continue to cause concern, especially when a new vaccine is introduced.

METHODS

A large case control study with immunisation data on 307 SIDS cases and 971 controls.

RESULTS

SIDS cases were immunised less frequently and later than controls. Furthermore there was no increased risk of SIDS in the 14 days following immunisation. There was no evidence to suggest the recently introduced hexavalent vaccines were associated with an increased risk of SIDS.

CONCLUSIONS

This study provides further support that immunisations may reduce the risk of SIDS.

[Case report of successful therapy of necrotizing fasciitis using a device of vacuum assisted closure]

Successful wound management is reported in a case of extended and life threatening necrotizing fasciitis of the leg of a poly-morbid older woman by use of standards of septic surgery (sufficient excision of necrotic tissue, use of bacteria adapted antibiotics, programmed wound revisions) and use of an industrial supplied device of vacuum assisted closure (V.A.C.).

Infection, health problems, and health care utilisation, and the risk of sudden infant death syndrome

AIM

To examine whether symptoms suggestive of infection, health problems, and health care utilisation are risk factors for SIDS.

METHODS

Matched case-control study with 333 SIDS infants and 998 control infants matched for region, age, gender, and reference sleep. Information was obtained by parental interview, paediatrician completed questionnaire, and hospital admission data.

RESULTS

No symptoms were associated with SIDS after adjustment for potential confounders. Illness in the last four weeks as reported by the paediatrician did not differ between cases and controls. Developmental problems and special investigations at any stage of life significantly increased the risk of SIDS (adjusted OR = 2.14 and 2.07). Admission to hospital after the first week of life was associated with an increased risk of SIDS (adjusted OR = 1.88).

CONCLUSION

Symptoms of infection and illness are no longer risk factors for SIDS in communities such as Germany where few infants sleep prone. The increased risk of SIDS with developmental problems may indicate that infants which subsequently die of SIDS are abnormal or in some way vulnerable.

German study on sudden infant death (GeSID): design, epidemiological and pathological profile

The German study on sudden infant death (GeSID) is a multi-centre case-control study aiming at the assessment of etiological factors and risk factors of SIDS. This report describes the study design and the methods applied and presents some general findings. Between 1998 and 2001, 455 cases of sudden and unexpected death of infants aged between 8 and 365 days were recruited into the study. The study comprised at least 11 out of the 16 German states with 18 centres involved. In 1999 and 2000, 75% of all SIDS cases registered with the Federal Office of Statistics (ICD 10/R95, n=384) in the study area were recruited into the study (n=286). A standardised autopsy including extended histology, microbiology, virology, toxicology and neuropathology investigations was carried out. Of the parents 82% (n=373) agreed to fill in an extensive questionnaire containing 120 questions reflecting all important aspects of the infant's development. For each SIDS case, the parents of three living control infants were interviewed. These controls were matched for age, gender and region (n=1,118). The response rate of the controls was 58.7%. Data were linked with medical records obtained from obstetrics departments, the children's hospitals, and general practitioners. Death scene investigation was performed in 4 study areas (cases: n=64, controls: n=191). All cases were classified into one of 4 categories using defined criteria: 7.3% of the children were assigned to category 1 (no pathological findings: SIDS), 61.1% to category 2 (minor findings: SIDS+), 20.4% to category 3 (severe findings: SIDS+) and 11.2% to category 4 (findings which explained the death: non-SIDS). In case conferences the previous history and circumstantial factors were included and an extended category (E-cat.) was defined. The consideration of these factors for the final classification is of great importance in the causal explanation of some cases. An analysis of 18 main variables in cases of categories 1-3 (SIDS) compared to the cases of category 4 (non-SIDS) showed significant differences for the sleeping position, coughing the day before death and breast-feeding indicating that the cases of both groups should be separated for further analyses.

Tc and Re chelates of 8alpha-amino-6-methyl-ergoline: synthesis and affinity to the dopamine D2 receptor

The influence of structural changes at the 8alpha-amino position of 8alpha-amino-6-methyl-ergoline on the lipophilicity and affinity to the D2 receptor was studied. 8alpha-amino-6-methyl-ergoline (1) was converted into the derivatives (2a-f) by mercaptoacetylation of the amino group to make it possible to prepare the rhenium and technetium complexes (3, 4a,b). Binding tests on cloned human dopamine D2 receptors show that the affinities of the coordination compounds (IC50 values between 50 and 240 nM) are less than those of the derivatives 2a-f (IC50=3-50 nM) but more than those of the parent compound 1. Biodistribution studies of the Tc complexes 4a,b performed on Wistar rats show a slow blood clearance with substantial accumulation and retention in the liver and kidneys and low brain uptake.

Long-term oxygen therapy in the home

Medicare introduced new policies and guidelines for oxygen therapy in 1998 including the HCFA 484.2, Certificate of Medical Necessity: Oxygen. This article outlines how nurses can collaborate with prescribers and oxygen suppliers to ensure that patients receive the appropriate oxygen delivery system that best meets their lifestyle, needs, and oxygen prescription.

Is absolute noninvasive temperature measurement by the Pr[MOE-DO3A] complex feasible

Recently, the feasibility of the praseodymium complex of 10-(2-methoxyethyl)-1,4,7,10-tetraaza-cyclododecane-1,4,7-tr iacetate (Pr[MOE-DO3A]) for non-invasive temperature measurement via 1H spectroscopy has been demonstrated. Particularly the suitability of the complex for non-invasive temperature measurements including in vivo spectroscopy without spatial resolution as well as first spectroscopic imaging measurements at low temporal resolution (> or = 4 min) and high temporal resolution (breath hold, approximately 20 s) has been shown. As of today, calibration curves according to the particular experimental conditions are necessary. This work aims to clarify whether the Pr[MOE-DO3A] probe in conjunction with 1H-NMR spectroscopy allows non-invasive absolute temperature measurements with high accuracy. The measurement results from two different representative media, distilled water and human plasma, show a slight but significant dependence of the calibration curves on the surrounding medium. Calibration curves in water and plasma were derived for the temperature dependence of the chemical shift difference (F) between Pr[MOE-DO3A]'s OCH3 and water with F = -(27.53 +/- 0.04) + (0.125 +/- 0.001) x T and F = -(27.61 +/- 0.02) + (0.129 +/- 0.001) x T, respectively, with F in ppm and T in degrees C. However, the differences are minuscule even for the highest spectral resolution of 0.001 ppm/pt, so that they are indistinguishable under practical conditions. The estimated temperature errors are +/- 0.18 degrees C for water and +/- 0.14 degrees C for plasma and with that only slightly worse than the measurement accuracy of the fiber-optical temperature probe (+/- 0.1 degrees C). It can be concluded that the results obtained indicate the feasibility of the 1H spectroscopy method in conjunction with the Pr[MOE-DO3A] probe for absolute temperature measurements, with a maximum accuracy of +/- 0.2 degrees C.

Cyclin A-dependent kinase activity affects chromatin binding of ORC, Cdc6, and MCM in egg extracts of Xenopus laevis

The initiation of DNA replication in eukaryotes requires the loading of the origin recognition complex (ORC), Cdc6, and minichromosome maintenance (MCM) proteins onto chromatin to form the preinitiation complex. In Xenopus egg extract, the proteins Orc1, Orc2, Cdc6, and Mcm4 are underphosphorylated in interphase and hyperphosphorylated in metaphase extract. We find that chromatin binding of ORC, Cdc6, and MCM proteins does not require cyclin-dependent kinase activities. High cyclin A-dependent kinase activity inhibits the binding and promotes the release of Xenopus ORC, Cdc6, and MCM from sperm chromatin, but has no effect on chromatin binding of control proteins. Cyclin A together with ORC, Cdc6 and MCM proteins is bound to sperm chromatin in DNA replicating pseudonuclei. In contrast, high cyclin E/cdk2 was not detected on chromatin, but was found soluble in the nucleoplasm. High cyclin E kinase activity allows the binding of Xenopus ORC and Cdc6, but not MCM, to sperm chromatin, even though the kinase does not phosphorylate MCM directly. We conclude that chromatin-bound cyclin A kinase controls DNA replication by protein phosphorylation and chromatin release of Cdc6 and MCM, whereas soluble cyclin E kinase prevents rereplication during the cell cycle by the inhibition of premature MCM chromatin association.

Phosphorylation of replication protein A middle subunit (RPA32) leads to a disassembly of the RPA heterotrimer

Replication protein A (RPA), the major eukaryotic single-strand specific DNA binding protein, consists of three subunits, RPA70, RPA32, and RPA14. The middle subunit, RPA32, is phosphorylated in a cell cycle-dependent manner. RPA occurs in two nuclear compartments, bound to chromatin or free in the nucleosol. We show here that the chromatin-associated fraction of RPA contains the phosphorylated forms of RPA32. Treatment of chromatin with 0.4 M NaCl releases bound RPA and causes a separation of the large and the phosphorylated middle RPA subunit. Unmodified RPA in the nucleosolic fraction remains perfectly stable under identical conditions. Phosphorylation is most likely an important determinant of RPA desintegration because dialysis from 0.4 to 0.1 NaCl causes the reformation of trimeric RPA only under dephosphorylating conditions. Biochemical studies with isolated Cyclin-dependent protein kinases showed that cyclin A/CDK1 and cyclin B/CDK1, but not cyclin E/CDK2, can phosphorylate human recombinant RPA in vitro. However, only a small fraction of in vitro phosphorylated RPA desintegrated, suggesting that phosphorylation may be one, but probably not the only, determinant affecting subunit interaction. We speculate that phosphorylation and changes in subunit interaction are required for the proposed role of RPA during the polymerase switch at replication forks.

Lipoprotein (a): its role in childhood thromboembolism

PURPOSE

Elevated lipoprotein (a) [LP (a)] concentrations are independent risk factors of coronary heart disease or stroke in young adults. To clarify its role in childhood thromboembolism, Lp (a) was measured in 72 children with thromboembolism.

METHODS

In addition to Lp (a), defects of the protein C anticoagulant system, antithrombin, and antiphospholipid antibodies were investigated in children with arterial (n = 36) or venous (n = 36) thrombosis.

RESULTS

Enhanced Lp (a) >50 mg/dL was diagnosed in 8 out of 36 children with arterial and 5 out of 36 patients with venous thrombosis. Of the 72 children, 25 showed the factor V Leiden mutation, 10 showed protein C deficiency, 2 showed antithrombin deficiency, and 4 showed primary antiphospholipid syndrome. Three children with increased Lp (a) were heterozygous for the factor V Leiden mutation, and 1 girl showed additional protein C deficiency.

CONCLUSIONS

Data of this study indicate that increased concentrations of Lp (a) play an important role in childhood thrombosis.

[PAF-antagonists with a phospholipid structure. 1. Phospholipids with hetero-arene head groups: synthesis, characterization and determination of the action of structural elements]

A series of analogues of platelet-activating factor (PAF) with heteroarene head groups have been synthesized, and tested for biological activities on blood platelets in vitro. In comparison with PAF most of the structural modifications exerted weak proaggregatory effects. The 4-(dimethylamino)pyridinium compound did not activate platelets but inhibited selectively PAF-induced platelet responses. These results point to a crucial role of the distance between the phosphoryl group and polar head for expression of PAF-antagonistic properties. Structural features of PAF-antagonist have been investigated by two-dimensional proton NMR spectroscopy, and proposed a model with three-dimensional structure.