The lens of the eye: exposures in the UK medical sector and mechanistic studies of radiation effects.

The recommendation from the International Commission on Radiological Protection that the occupational equivalent dose limit for the lens of the eye should be reduced to 20 mSv year(-1), averaged over 5 years with no year exceeding 50 mSv, has stimulated a discussion on the practicalities of implementation of this revised dose limit, and the most appropriate risk and protection framework to adopt. This brief paper provides an overview of some of the drivers behind the move to a lower recommended dose limit. The issue of implementation in the medical sector in the UK has been addressed through a small-scale survey of doses to the lens of the eye amongst interventional cardiologists and radiologists. In addition, a mechanistic study of early and late post-irradiation changes in the lens of the eye in in-vivo-exposed mice is outlined. Surveys and studies such as those described can contribute to a deeper understanding of fundamental and practical issues, and therefore contribute to a robust evidence base for ensuring adequate protection of the eye while avoiding undesirable restrictions to working practices.

Circulating pro- and anticoagulant levels in normal and complicated primigravid pregnancies and their relationship to placental pathology.

We aimed to compare the changes in factor VIII:C, antithrombin, protein C, protein S and fibrinogen in a cohort of low-risk primigravida who developed maternal or fetal complications to those who had uncomplicated pregnancies and to correlate these findings with placental pathology. This is a case-control study of 170 cases and 122 controls selected from a prospective cohort of 1,011 low-risk primigravida. Significantly elevated levels of factor VIII:C and significantly decreased levels of antithrombin were seen in women who developed pre-eclampsia (p <0.001), placental infarction (p < 0.001) or had infants with a birth weight < 3rd centile (p < 0.001). Placental villous dysmaturity was significantly associated with raised factor VIII:C (p < 0.001). Women who developed pre-eclampsia showed elevated fibrinogen at 14 weeks (p = 0.03). Significantly higher than normal pregnancy levels of factor VIII:C, in tandem with significantly lower antithrombin levels associated with certain adverse pregnancy outcomes, may be related to underlying placental insufficiency. This is supported by associated placental findings.

Ponderal index (PI) vs birth weight centiles in the low-risk primigravid population: which is the better predictor of fetal wellbeing?

Our objective was to compare Ponderal index (PI) with birth weight centiles as predictors of perinatal morbidity and to determine which best reflects the presence of placental disease. We prospectively recruited 1,011 low-risk primigravidas and calculated PI and birth weight centiles following delivery. Perinatal morbidity was defined as: pre-term birth (PTB); fetal acidosis; an Apgar score <7 at 5 min or neonatal resuscitation. Placental disease was defined as chronic uteroplacental insufficiency (CUPI); villous dysmaturity; infection or vascular pathology. Ponderal index was statistically reduced (25.33 vs 27.79 p =0.001) and the incidence of infant birth weight <9th centile was statistically higher (11.1% vs 5.1%; p =0.004) in cases with PTB and in CUPI (26.23 vs 27.84; p =0.001 and 28.2.1% vs 10.4%; p =0.002). Both PI and infant birth weight centile <9th centile for gestational age correlate with PTB, however overall, both are poor predictors of neonatal and placental disease.

An evaluation of Brix refractometry instruments for measurement of colostrum quality in dairy cattle.

Acquisition of high quality colostrum is an important factor influencing neonatal calf health. Many methods have been used to assess the Ig concentration of colostrum; however, improved, validated evaluation tools are needed. The aims of this study were to evaluate both optical and digital Brix refractometer instruments for the measurement of Ig concentration of colostrum as compared with the gold standard radial immunodiffusion assay laboratory assessment and to determine the correlation between Ig measurements taken from fresh and frozen colostrum samples for both Brix refractometer instruments. This research was completed using 288 colostrum samples from 3 different farms. It was concluded that the optical and digital Brix refractometers were highly correlated for both fresh and frozen samples (r=0.98 and r=0.97, respectively). Correlation between both refractometer instruments for fresh and frozen samples and the gold standard radial immunodiffusion assay were determined to be very similar, with a correlation coefficient between 0.71 and 0.74. Both instruments exhibited excellent test characteristics, indicating an appropriate cut-off point of 22% Brix score for the identification of good quality colostrum.

Legislative advocacy is key to addressing teen driving deaths.

The increased crash risk of young, novice drivers, especially in their teenage years, has been a growing concern at both the state and federal levels. Teenage drivers are involved in fatal crashes at more than double the rate of the rest of the population per 100 000 licensed drivers. The best way of stemming these losses is to enact laws adopting graduated licensure systems that restrict young, novice drivers to conditions that reduce crash risk exposure when they first operate motor vehicles and to educate the public on the need for this legislation. Legislated teenage driving restrictions involve night-time vehicle driving restrictions, prohibitions on other teenage passengers, and the required presence of supervising adults. These restrictions are relaxed as teenage drivers successfully progress through initial and intermediate stages of graduated licensure before being granted unrestricted driver licenses. Unfortunately, many states have incomplete graduated licensing systems that need further legislative action to raise them to the desirable three-stage system that has been shown repeatedly to produce the greatest safety benefits. These state efforts should be buttressed by federal legislation that has proved to be crucial in allied driver behavioral concerns. Because reducing crash risk involves other strategies, stringent enforcement of primary seat belt laws as well as improved motor vehicle crash avoidance capabilities and crashworthiness must accompany efforts to reduce young driver crash risk.

Choriocarcinoma-presenting as a primary lesion of the cervix.

A 25 year old nulliparous Russian lady presented to the hospital complaining of abdominal pain and mild vaginal bleeding. In 1999 she was diagnosed with a molar gestation and required a dilatation and curettage. On this occasion, Beta human Chorionic Gonadotrophin (BhCG) levels were elevated and a trans-vaginal ultrasound scan suggested the presence of a left-sided pelvic mass. Investigations confirmed the presence of a choriocarcinoma of the cervix. Complete assessment by a multidisciplinary team was performed and chemotherapy (methotrexate) was commenced. This case of a twenty-five year old nulliparous woman highlights the importance of appropriate follow-up in cases of irregular genital tract bleeding with a past history of trophoblastic disease.

Analyses of the potential oxygen transfer capability in placentae from infants succumbing to sudden infant death syndrome.

BACKGROUND: Morphometric oxygen diffusive conductance (Dp) was estimated to assess the potential efficiency of oxygen transfer across the materno-fetal interface in placentae obtained from victims of sudden infant death syndrome (SIDS). STUDY DESIGN: SIDS placentae were retrieved from archived storage and classified into normal birth weight (NBW, n=16), or small for gestational age (SGA, n=9) and compared against control placentae (n=40) or SGA (n=24) placentae. A combination of stereological techniques and physiological constants were used to estimate total Dp. RESULTS: SIDS NBW cases showed a crucial reduction in fetal capillary surface area when compared with control placentae. SIDS SGA showed a number of deficiencies in basic volumetric and surface area parameters. Values for total and specific Dp in placentae in both SIDS groups were maintained at levels comparable with control and SGA cases, respectively. CONCLUSION: Since more reductions were observed in SIDS SGA group, this suggests that factors responsible for these reductions maybe associated with SGA rather than being SIDS-specific factors.

Morphometric assessment of the oxygen diffusion conductance in placentae from pregnancies complicated by intra-uterine growth restriction.

The morphometric oxygen diffusive conductance (D(p)) of the placenta provides a measure of the efficiency of oxygen transfer between the mother and the developing fetus. Any change in the D(p)may point towards possible adaptation in the light of altered oxygen transfer. Placentae from normal (n=40) and small for gestational age SGA (n=24) pregnancies were analysed using stereological techniques. Each placenta was uniform randomly sampled and tissue samples processed to wax infiltration and embedding using conventional histological preparatory methods. A combination of stereological techniques and physiological constants were used to estimate the partial conductances across the five major tissue compartments involved in oxygen transfer. There was a significant reduction in both fetal birthweight and placental weight in the SGA group when compared with controls. A decrease in both chorionic (S(cv)) and fetal capillary (S(fc)) surface area was also observed in SGA placentae when compared with controls (P>0.001). Villous membrane harmonic thickness (T(vm)) was reduced in the SGA placentae (2.33 microm) when compared with controls (2.67 microm P=0.019). This resulted in a reduction in the minimum D(p)in SGA placentae when compared with controls (P=0.023). Adjusting for fetal weight resulted in no difference in the specific diffusive conductance. Changes in T(vm)in SGA placentae combined with changes in basic surface areas were insufficient to maintain overall D(p)values comparable with control placentae.

Massive perivillous fibrinoid causing recurrent placental failure.

OBJECTIVE: To establish the incidence, recurrence rate and consequences of massive perivillous fibrinoid. DESIGN: Retrospective analysis of the histology of all placentas with a diagnosis of massive perivillous fibrinoid between 1991 and 1998, together with the maternal case records. SETTING: The histopathology department of the Rotunda Hospital, Dublin, Ireland. POPULATION: A relatively homogeneous group of pregnant women in the northern part of Dublin City, which is the catchment area for the Rotunda Hospital, delivered between 1991 and 1998. METHODS: Retrospective review of archival placental pathology and maternal charts. MAIN OUTCOME MEASURES: The incidence of massive perivillous fibrinoid, perinatal outcome and recurrence rate. RESULTS: The incidence of massive perivillous fibrinoid was 0.028%, with a recurrence rate of approximately 18%. All the infants suffered intrauterine growth restriction; there was a 31% fetal loss rate and a 33% preterm delivery rate. CONCLUSIONS: Massive perivillous fibrinoid is associated with intrauterine death, intrauterine growth restriction and preterm delivery. It has a significant recurrence rate and both the clinical findings of intrauterine growth restriction and the postmortem findings imply a syndrome of chronic placental insufficiency.

Concentrations of antimony in infants dying from SIDS and infants dying from other causes.

OBJECTIVES: Raised concentrations of antimony have been found in infants dying of sudden infant death syndrome (SIDS). The presumed source of this antimony is toxic gases generated from fire retardants that are present in cot mattresses. The aim of this study was to determine the role of antimony in SIDS. DESIGN: Samples of liver, brain, serum, and urine were collected from all patients dying from SIDS and a group of aged matched control infants who had died of other causes. SETTING: Nationwide study in Ireland. SUBJECTS: 52 infants dying from SIDS and 19 control infants aged > 7 days and < 1 year. RESULTS: The median concentration of antimony in the liver and brain of infants dying of SIDS was < 1 ng/g, with no difference detected between the infants dying from SIDS and the control infants. The range of antimony in the serum of infants dying of SIDS was 0.09-0.71 microg/litre (median, 0.26). Although no difference was found between infants dying from SIDS and control infants, SIDS infants were found to have higher concentrations when compared with healthy infants in the 1st year of life, probably as a result of release of antimony into serum after death. Urine antimony concentrations in infants dying from SIDS were < 3.91 ng/mg (corrected for creatinine) and similar to values found both in control infants and healthy infants. CONCLUSION: There is no evidence to support a causal role for antimony in SIDS.