Magnesium and phosphorus distribution in the avian eggshell.

Magnesium and phosphorus are major inorganic constituents of the avian eggshell. The Mg/Ca ratio has been used as a palaeothermometer in a range of calcite biominerals. Eggshells provide the opportunity to examine the Mg/Ca ratio of a calcite biomineral produced in a constant temperature environment. Mg distribution is not constant throughout the shell, decreasing from nucleation until after fusion of the mammillary caps and then increasing to termination. This indicates that temperature of deposition is not the only factor controlling the Mg content of this biomineral system. There is a greater increase in magnesium concentration in the outer region of eggshells from older birds. The variation in magnesium concentration does not appear to correlate with organic content. Phosphorus occurs in the outer quarter of the eggshell and rises to termination and is therefore not confined to cuticular vesicles.

Pregnancy and drug addiction--long-term consequences.

With the prevalence of drug addiction amongst young women rising in the United Kingdom the problems associated with pregnancy in this group are increasingly being reported. An attempt has been made to determine whether the birth of a baby is a sufficient stimulus for the mother to cease her drug of addiction. Between the years 1966 and 1988, 86 such mothers gave birth at St Mary's Hospital, London, whom we were able to trace for at least one year after their last delivery. The results show that the majority of mothers continued with their drug use and where this is so the chances of the child remaining with her are markedly reduced. Discussion centres around possible ways of identifying those likely to succeed in drug withdrawal during pregnancy and the need for increasing and continued support for these mothers and their babies after they have left hospital.

Drug addiction in pregnancy.

32 pregnancies in 29 drug-addicted women were studied ouver eight years in one obstetric department working in close liaison with a drug dependency centre. Of the 24 pregnancies which came to term, only 10 were seen at the antenatal clinic before 22 weeks' gestation. 19 of the women were addicted to heroin or methadone or a mixture of both, 4 were taking soft drugs, and 1 was taking pethidine only. Labour commenced spontaneously in 17 pregnancies and was induced in 7. All labours lasted less than twenty hours. 23 infants survived. Those born to the mother taking pethidine and to 4 mothers who withdrew their drug of dependence four weeks before delivery showed no signs of narcotic withdrawal, but 13 out of 14 infants born to mothers taking heroin or methadone developed narcotic withdrawal syndrome. It is recommended that drug therapy during pregnancy in addicts should be supervised by a psychiatrist known to the patient and that oral methadone be substituted for heroin. Planned induction will ensure delivery in hospital, at the hospital which has supervised the pregnancy. Babies in danger of developing narcotic withdrawal syndrome should be observed in the special care baby unit for the first week of life.

Unexpected home confinement.

An analysis of 100 consecutive cases of unattended home confinements has shown that, while precipitate labour is an important factor, inadequate preparation and instruction of the patient are the commonest causes.

Adenocarcinoma of the uterine cervix a clinical and pathological appraisal.

Twenty-six cases of primary adenocarcinoma of the cervix are analyzed. Their clinical features are described and attention is drawn to the variable histological pattern of these tumors.

Temazepam and trimeprazine compared with placebo as premedication in children. An investigation extended into the first 2 weeks at home.

Temazepam, trimeprazine and placebo were compared as premedication in 85 children undergoing routine otolaryngological operations. Premedication with trimeprazine caused significantly more sedation than temazepam or placebo in patients on arrival in the anaesthetic room (P less than 0.02). Recovery time was significantly longer after trimeprazine than temazepam or placebo (P less than 0.012). Significantly more children (P less than 0.05) failed to recall a picture shown immediately before induction after trimeprazine and temazepam than with placebo. Fewer patients vomited after operation with trimeprazine than with temazepam or placebo (P less than 0.01). The majority of children exhibited some behavioural problem during the first 2 weeks at home, although this rarely lasted for more than a few days. More children exhibited apathetic/withdrawn behaviour after receiving placebo (P less than 0.05), although the significance of this should be interpreted with caution.

Organic matrix morphology and distribution in the palisade layer of eggshells sampled at selected periods during lay.

1. 1 cm2 pieces of eggshells from a commercial battery flock were plasma etched to remove the outer shell membranes. 2. They were decalcified using EDTA (200 g/l, pH 6.9 to 7.0) in paraformaldehyde (20 g/l) and 25% gluteraldehyde (20 ml in 0.98 l) in phosphate buffer, then prepared for light and transmission electron microscopy. 3. Light microscopy revealed a differential distribution of matrix material within all 3 regions of the palisade layer at the beginning of lay. 4. Transmission electron microscopy revealed a more even distribution of matrix at the beginning of lay, although morphological differences were observed. At the end of lay all 3 regions showed an increase in % matrix and vesicles/10 cm2 of micrograph compared to the middle and beginning of lay periods. 5. It is hypothesised that matrix vesicles are involved in the regulation of the physiochemical environment within the forming eggshell and that the decline in shell quality associated with the end of lay is related to a concomitant change in matrix quality.

Transmission electron microscopy of the vertical crystal layer and cuticle of the eggshell of the domestic fowl.

1. Eggshell pieces (1 cm2) were decalcified using a solution of EDTA (200 g/litre, pH 6.9 to 7.0) in paraformaldehyde (2 g/litre) and glutaraldehyde (0.5 g/litre) in phosphate buffer. 2. They were prepared for transmission electron microscopy (TEM). 3. TEM identified a vertically aligned matrix associated with the vertical crystal layer (VCL). It is hypothesised that the vertical orientation of calcite crystals in the VCL is closely linked to this vertical matrix. 4. TEM also revealed the presence of a 2-layered cuticle, the inner layer containing vesicles which were absent in the outer. 5. Cuticular vesicles contain hydroxyapatite and are thought to play a role in the termination of shell formation. The current paper presents data relating to microbial apatitic systems that strengthen this hypothesis.