Haemorrhagic disease of the newborn in the British Isles: two year prospective study.

OBJECTIVE--To determine the incidence of haemorrhagic disease of the newborn in the British Isles, study risk factors, and examine the effect of vitamin K prophylaxis. DESIGN--Prospective survey of all possible cases of haemorrhagic disease of the newborn as reported by consultant paediatricians using the monthly notification cards of the British Paediatric Surveillance Unit and a follow up questionnaire for each case to validate the diagnosis and accrue further data. SETTING--Britain (England, Scotland, and Wales) and Ireland (Northern Ireland and the Irish Republic) during December 1987 to March 1990. PATIENTS--27 infants classified as having confirmed (n = 25) or probable (n = 2) haemorrhagic disease of the newborn. RESULTS--24 of the 27 infants were solely breast fed. 10 suffered intracranial haemorrhage; two of these died and there was clinical concern about the remainder. 20 infants had received no vitamin K prophylaxis, and seven had received oral prophylaxis. Relative risk ratios for these groups compared with babies who had received intramuscular vitamin K were 81:1 and 13:1 respectively. Six infants had hepatitis (alpha 1 antitrypsin deficiency in four), unsuspected until presentation with haemorrhagic disease of the newborn, of whom four had received oral prophylaxis. One other baby had prolonged jaundice. One mother had taken phenytoin during pregnancy. CONCLUSIONS--All newborn infants should receive vitamin K prophylaxis. Intramuscular vitamin K is more effective than oral prophylactic regimens currently used in the British Isles.     

The origin of P elements in Drosophila melanogaster.

The P family of transposable genetic elements is thought to be a recent addition to the Drosophila melanogaster genome. New evidence suggests that the elements came from another Drosophila species, possibly carried by parasitic mites. The transposition mechanism of P elements involves DNA gap repair which may have facilitated their rapid spread through D. melanogaster worldwide. These results provide new insight into the process of a transposon's invasion into a new species and the potential risk of extinction such an invasion might entail.     

Magnetic circular dichroism and electron paramagnetic resonance studies of hydrogenases I and II from Clostridium pasteurianum

The two iron-only hydrogenases (I and II) from Clostridium pasteurianum have been investigated by variable temperature magnetic circular dichroism (MCD) and electron paramagnetic resonance (EPR) spectroscopies. Samples were studied both reduced with dithionite under an atmosphere of H2 and after oxidation with thionine. The results are consistent with four and two [4Fe-4S]1+,2+ (F)-clusters in hydrogenases I and II, respectively. All four F-clusters are reduced and paramagnetic in reduced hydrogenase I, with up to one exhibiting an S = 3/2 ground state and the remainder having conventional S = 1/2 ground states. Both F-clusters have S = 1/2 ground states in reduced hydrogenase II; however, one appears to be only partially reduced under the conditions used for reduction. MCD studies of the oxidized enzymes show no temperature-dependent features in the visible region which can be attributed to the EPR-active S = 1/2 hydrogen-activating cluster, suggesting predominantly oxygen and nitrogen coordination for the iron atoms of this center. However, temperature-dependent MCD transitions arising from a hitherto undetected S greater than 1/2 Fe-S clusters are apparent in both oxidized hydrogenases. Detailed EPR studies of oxidized hydrogenase I revealed resonances from an S = 3/2 species, however, spin quantitation reveals this to be a trace component that is unlikely to be responsible for the observed low temperature MCD spectrum. The nature and origin of these S greater than 1/2 Fe-S clusters are discussed in light of the available spectroscopic data for these and other iron-only hydrogenases.     

A simple method to test condoms for penetration by viruses.

A method by which virus penetration through condoms can be tested with simple, inexpensive equipment is described. The method uses chi X174 bacteriophage as the challenge virus and physiologically relevant pressure. Penetration by 0.1 microliters (or less) of challenge suspension can be readily detected. As examples, latex and natural-membrane condoms were examined.     

Methods in clinical hemorheology: the continuous measurement of arterial blood density and blood sound speed in man

Both blood density and sound speed are closely related to total protein concentration in blood and, as a consequence, to rheologically important parameters of blood. Two methods that permit continuous measurement of these properties, the mechanical oscillator technique and the new ultrasonic technique, were used for measuring blood protein concentration over a continuous period of time in a group of hemodialysis patients and in volunteers. It was seen that the concentration of the components of blood varies considerably. This variability is related to transport phenomena within as well as to the flow of masses across the cardiovascular compartment. From the continuous measurement of concentrations during hemodialysis treatment, relative changes in blood volume can be recorded in order to control the fluid balance of the patient. Rapid fluctuations at the macroscopic scale with periods of 5 to 30 seconds are due to heterogeneities at the microscopic scale and to the particular rheological behaviour of the red blood cells at the level of the capillaries and the small blood vessels. The amplitude of rapid oscillations increased up to 1.2% in terms of hematocrit values when there was rhythmic, spontaneous breathing at various frequencies. The measurement of concentrations at an accessible measuring site may be used to investigate the rheology of blood in the human microvasculature.     

Cytokine production in a model of wound healing: the appearance of MIP-1, MIP-2, cachectin/TNF and IL-1

Macrophages are essential for normal wound repair and many of their effects on healing wounds are likely to be mediated by the secretion of cytokines. This study examines the appearance of messenger RNA (mRNA) for cachectin/tumor necrosis factor (TNF), IL 1, and macrophage inflammatory proteins 1 and 2 (MIP-1 and MIP-2), as well as the mature peptides, in a model of wound healing using wound chambers. RNA for all four cytokines can be detected in wound inflammatory cells by polymerase chain reaction amplification throughout the first 7 days. Cachectin/TNF and IL 1 protein levels peaked on the first day after wound chamber implantation, and MIP-1 and MIP-2 were detected only on day 3. The data suggest that these cytokines participate in the early inflammatory response to wounding.