Showing papers by "Queen's University Belfast published in 1983"

Temperature‐dependent sex determination in Alligator mississippiensis

Abstract: The structure of the reproductive systems of hatchling and 1 -year-old alligators was investigated macroscopically and histologically. Sex is fully determined at the time of hatching and irreversible thereafter. Constant temperature laboratory experiments revealed that the sex of Alligator miuissippiensis is determined by the temperature of egg incubation, 30°C or below producing females, and 34°C or above, males. Experiments in which eggs were shifted from female-producing temperatures to male-producing temperatures and vice versa at weekly intervals during incubation demonstrated that the temperature-sensitive period for sex determination is around 20 and 35 days after egg laying. In the wild, temperature probes were placed in alligator nests constructed in three different habitats: wet marsh, dry marsh and levee (elevated firm ground). The position of the eggs in the nests were mapped at 60 days incubation and the sex of the enclosed hatchlings correlated with the nest temperatures at that site. Levee nests were hot (34°C) and hatched approximately 100% males. Wet marsh nests were cool (30°C) and hatched approximately 100% females. Dry marsh nests had an intermediate temperature profile, the hottest location (34°C) being the top centre of the nest. Males developed from eggs in this location and females from eggs around the periphery and base of the nest. The sex ratio in dry marsh nests was five females to one male. The natural sex ratio at hatching was determined for a large area of representative habitat for four consecutive years and averaged five (±0.7) females to one male. Females hatched from eggs incubated at 30°C weighed more than males hatched from eggs incubated at 34°C because the former contained more absorbed abdominal yolk. These extra energy reserves enable females to grow faster and become larger than males in the early years of life. This means that heavy females become sexually mature ahead of either light females or light males, and because of the reproductive lifestyle of alligators, this early maturity constitutes a selective biological advantage for the evolution of temperature-dependent sex determination in Alligator mississippiensis. The occurrence of temperature-dependent sex determination in alligators has wide-ranging implications for embryological, teratological, molecular, phylogenetic, conservation and farming studies.

The use of the fractal dimension to quantify the morphology of irregular‐shaped particles

Abstract: For several decades, sedimentologists have had difficulty in obtaining an efficient index of particle form that can be used to specify adequately irregular morphology of sedimentary particles. Mandelbrot has suggested the use of the fractal dimension as a single value estimate of form, in order to characterize morphologically closed loops of an irregular nature. The concept of fractal dimension derives from Richardson's unpublished suggestion that a stable linear relationship appears when the logarithm of the perimeter estimate of an irregular outline is plotted against the logarithm of the unit of measurement (step length). Decreases in step length result in an increase in perimeter by a constant weight (b) for particles whose morphological variations are the same at all measurement scales (self-similarity). The fractal dimension (D) equals 1.0-(b), where b is the slope coefficient of the best-fitting linear regression of the plot. The value of D lies between 1.0 and 2.0, with increasing values of D correlating with increasing irregularity of the outline. In practice, particle outline morphology is not always self-similar, such that two or possibly more fractal elements can occur for many outlines. Two fractal elements reflect the morphological difference between micro-scale edge textural effects (D1) and macro-scale particle structural effects (D2) generated by the presence of crenellate-edge morphology (re-entrants). Fractal calibration on a range of regular/irregular particle outline morphologies, plus examination of carbonate beach, pyroclastic and weathered quartz particles indicates that this type of analysis is best suited for morphological characterization of irregular and crenellate particles. In this respect, fractal analysis appears as the complementary analytical technique to harmonic form analysis in order to achieve an adequate specification of all types of particles on a continuum of irregular to regular morphology.

Evidence for the role of Ca2+ ions in tip extension in pollen tubes

Abstract: Pollen tube growth is shown to be inhibited by both suboptimal ( 10−3 M) Ca2+ ion concentrations. Tip extension rates are independent of Ca2+ ion concentration over the optimal range. Changes in the structure of the tips of pollen tubes after transfer to inhibitory Ca2+ ion conditions provide evidence in support of our proposed mechanism of pollen tube tip growth (J. theor. Biol.98, 15–20, 1982). It is clearly demonstrated that tip extension is controlled, not only by the rate of vesicle fusion, but also by the state of plasticity of the tip; these processes appear to be sensitive to changes in Ca2+ ion concentration.

Circulation to Skin and Adipose Tissue

Abstract: The sections in this article are: 1 Skin 1.1 Introduction 1.2 Arrangement of Vessels 1.3 Arteriovenous Anastomoses 1.4 Skin Vessels as Heat Exchangers 1.5 Measurement of Flow 1.6 Vasomotor Innervation 1.7 Reflex Control of Flow 1.8 Responses to Physical Stimuli 1.9 Responses to Humoral Agents 2 Adipose Tissue 2.1 Introduction 2.2 Arrangement of Vessels 2.3 Vascular Exchange 2.4 Measurement of Flow 2.5 Vasomotor Innervation 2.6 Reflex Control of Flow 2.7 Responses to Physical Stimuli 2.8 Responses to Humoral Agents

Cell cycle control by timer and sizer in Chlamydomonas

Abstract: Conservation of cell cycle control mechanisms is indicated by the presence of functionally homologous division control genes in unrelated yeasts and by the nonspecific action of oncogenes, but it remains uncertain what property of a growing cell results in the initiation of events leading to division. Response to a critical size is indicated by the longer growth period of smaller cells prior to division, which is consistent with deferment of division events until a minimum size is attained; however, in the same cell types faster growing cells are larger and this is more easily explained if division follows a timed period during which faster growing cells grow more, as is postulated for mammalian cells. Therefore, either time- or size-dependent controls might be the sole significant mechanism; we report here, however, that both controls do function in Chlamydomonas since cycle duration is under timer control and cell size determines the number of division rounds committed at the end of each cycle, and hence whether 2, 4, 8 or 16 daughter cells are formed.

Shell Wars: Assessment Strategies and the Timing of Decisions in Hermit Crab Shell Fights

Abstract: The shell fighting behaviour of the hermit crab Pagurus bernhardus was observed under experimental conditions. The relative sizes of the crabs and shell quality of the larger crab influenced the probability of occurrence of a shell fight. These two factors along with the quality of the smaller crab's shell influenced the probability of an escalated fight occurring. During a shell fight, the attacker was able to assimilate information concerning the defender's shell and to compare it with the shell in possession. On the basis of this comparison the attacker decided whether or not to evict the defender and effect a shell change. The time that the attacker took in assessment of the opponent's shell was influenced by a) the quality of the attacker's own shell and b) the ease of discrimination between the qualities of the two shells. Thus decisions were easier in some instances than in others. The defending crab did not have access to information about the attacker's shell and therefore could only estimate the quality of its own shell. This asymmetry of information experienced by the crabs ensured that the attacker decided the outcome of a shell fight.

Glycopyrrolate: pharmacology and clinical use

Abstract: This is a review of glycopyrrolate whose function in clinical practice is compared with that of atropine.

Pharmacokinetic evaluation of ICI 35 868 in man. Single induction doses with different rates of injection.

Abstract: Blood concentrations of ICI 35 868 have been measured in patients following a single bolus dose of 2 mg kg−1. Three different rates of injection of the anaesthetic agent (3–5s, 20s and 40 or 50s) were examined. Pharmacokinetic indices, derived from blood concentrations of ICI 35 868, were independent of the speed of injection. The blood profiles could be described by a two-compartment open model with a mean a-phase half-life of 2.5min and a mean β-phase half-life of 54.5min. The mean total body clearance was 3454 ml min−1. Similar data were obtained from a 4-mgkg−1 dose. The mean recovery time (4.4 min) and concentration of ICI 35 868 at awakening (1.05 ug ml−1) were also independent of the rate of injection. Using the derived pharmacokinetic model, predictions of drug concentrations have been made for repeated bolus doses, or infusions, of ICI 35 868

Protein-binding displacement interactions and their clinical importance

Abstract: The binding of drugs to proteins is an important pharmacokinetic parameter. Many methods are available for the study of drug protein binding phenomena and there are also many ways to interpret the binding data. Although much emphasis has been placed on the binding of drugs in the plasma, binding also takes place in the tissues. Displacement interactions involving plasma or tissue binding sites have been implicated as the causative mechanisms in many drug interactions. However, the importance of plasma binding displacement as a mechanism of drug interactions. However, the importance of plasma binding displacement as a mechanism of drug interaction has been overestimated and overstated, being based largely on in vitro data. Because displaced drug can normally distribute out of the plasma compartment, increases of free drug concentrations are usually transient and therefore will not give rise to changed pharmacological effects in the patient. Those clinically important drug interactions formerly considered to be caused via displacement from plasma binding sites usually have another interaction mechanism involved; commonly decreased metabolism or renal elimination also takes place. Plasma binding displacement interactions, however, do become important clinically in certain specific situations, namely, when the displacing drug is administered quickly to the patient by the intravenous route, during therapeutic drug monitoring, and in certain drug disposition studies which involve the use of a heparin lock for blood sampling. Tissue binding displacement interactions have a greater potential to cause adverse effects in the patient as in this case drug will be forced from extravascular sites back into the plasma. The resulting increased drug plasma levels will lead to enhanced pharmacological effects and, possibly, frank toxicity. Displacement of drugs from binding sites simultaneously in both the plasma and in the tissues will combine the effects seen after displacement from the separate areas. Due to decreased binding in both areas, the free drug concentration in the plasma will increase leading to overactivity of the displaced drug.

Formation of an adenine-thymine photoadduct in the deoxydinucleoside monophosphate d(TpA) and in DNA.

Abstract: A photoadduct is formed between the adenine (A) and thymine (T) bases of the deoxydinucleoside monophosphate d(TpA) when it is irradiated at 254 nanometers in aqueous solution. Treatment of the photoadduct with acid converts it specifically into a fluorescent hydrolysis product, C7H7N3O, incorporating the position-8 carbon of adenine and the methyl group of thymine. Isolation of the fluorescent hydrolysis product from acid hydrolyzates of oligo- and polydeoxyribonucleotides has shown that the photoadduct is formed by ultraviolet irradiation of d(pTpA), d(TpApT), d(TpApTpA), poly(dA-dT), and both single- and double-stranded DNA.

Hydrogen chemical potentials and diffusion coefficients in hydrogen diffusion membranes

Abstract: Palladium and palladium alloys are quite widely used as membranes for hydrogen permeation, because of their resistance to embrittlement and to irreversible deformations during cycles of absorption and desorption of hydrogen1–3. The isothermal relationships between hydrogen diffusion coefficient, DH, and hydrogen content, n (ratio of hydrogen/metal atoms) has both technological and academic interest. The most detailed form of relationships2,3 between DH and n have been those reported for deuterium in Pd75Ag25 by Hickman4 within the temperature range 300–500°C, and for protium in Pd7Ag23 within the range 30–75°C by Kussner5. For increasing values of n up to n ∼ 0.2, Kussner5 reported significant corresponding decreases of DH (by a factor of ∼ 8 from n=0 up to n ∼ 0.16 at 30°C). This is the reverse of trends in the values of DH with increasing n suggested by measurements of anelastic effects3,6,7 and also by the permeation rate measurements of Hickman4 at 300 and 400°C. Here we report measurements of diffusion through Pd81Pt19 alloy, the results of which are consistent with Gorskii's hypothesis relating long-range anelastic diffusion of lattice interstitials to elastic strain gradients.

The quest for the inhibitory neurotransmitter in bovine tracheal smooth muscle.

Abstract: The effect of inhibitory nerve stimulation on the mechanical, membrane potential and membrane conductance responses of isolated bovine tracheal smooth muscle has been studied. Membrane responses were measured in a sucrose-gap apparatus. In order to record inhibitory responses, it was necessary to increase tone in the preparation by applying a drug such as histamine. When tone was raised, repetitive field stimulation of intrinsic nerves caused depolarization and contraction, followed by relaxation and a suppression of histamine-induced slow waves. Hyperpolarization of the membrane was only seen following prolonged nerve stimulation, and there was no change in membrane conductance. The inhibitory effect of nerve stimulation was abolished by tetrodotoxin, but was not abolished by atropine, indomethacin, propranolol, naloxone or the purinergic blockers quinidine and theophylline. It was not satisfactorily mimicked by catecholamines, by γ-amino-n-butyric acid (GABA) or by purines. Nerves with catecholamine fluorescence could not be found in the tracheal muscle layer. Neither adrenergic nor purinergic types of nerve terminal could be found in the tracheal muscle layer during ultrastructural examination of over one thousand nerve profiles. Vasoactive intestinal peptide (VIP) caused relaxation of the histamine-contracted tracheal muscle, suppressed the slow wave and caused slight hyperpolarization at higher concentrations, without affecting the membrane conductance. VIP was found in samples of tracheal muscle at a mean concentration of 1·95 ng/g. When the effluent solution flowing past isolated tracheal muscle strips was assayed for VIP, samples collected during inhibitory nerve stimulation had much higher concentrations of the peptide than samples collected before stimulation, after stimulation, or during stimulation in the presence of tetrodotoxin (10–6 mol/l). The VIP content of the effluent during control periods was 73·8 pg/ml, and during stimulation was 167·5 pg/ml. It is suggested that VIP might be the non-adrenergic inhibitory neurotransmitter in bovine tracheal smooth muscle.

The adsorption of dyes in chitin. III. Intraparticle diffusion processes

Abstract: Intraparticle diffusion processes for the adsorption of dyestuffs onto chitin have been studied. The amount of dye adsorbed per gram of chitin has been plotted against the square root of time. The slope of this plot is linear and has been defined as a rate parameter k. This rate parameter has been determined for a number of process variables, including initial dye concentration, agitation, chitin particle size, chitin mass, temperature, and solution pH. However, sometimes two and even three linear regions are apparent on the root time plots indicating a possible branched pore mechanism. The controlling mechanisms are due to macropores and micropores in the chitin particle creating rapidly and slowly diffusing regions.

Arable Productivity in Medieval England: Some Evidence from Norfolk

Abstract: Statistics on crop yields for the period 1268–1430 from 62 demesnes in the eastern half of Norfolk are used to demonstrate a new method of measuring arable productivity. The method takes into account seeding rates, the frequency of cropping, and the relative importance of the different crops grown, and it acknowledges the existence of different farming regions. Within eastern Norfolk two such regions are shown to have existed, which cut right across estate affiliations and had radically different productivities. The wider implications of these findings are then discussed.

Pup recognition in Mus musculus: parental discrimination between their own and alien young.

Abstract: The responses of male and female mice each presented with a sequence of 4 pups from their own litter, a pup from another litter but of the same age and strain, and finally their own pup were noted. Both sexes spent longer sniffing the alien pup than the preceding own pup regardless of the age of pups at testing, and more time licking the alien pup on some test days. Young pups (Days 0-3; birth = Day 0) emitted fewer ultrasounds in the presence of a male than a female, but there was no quantitative difference in the vocalizations of own and alien pups. These data indicate that adult mice are able to discriminate between their own and alien offspring; this discrimination appears to be based upon olfactory and possibly gustatory cues rather than auditory ones.

Environmental discrimination based on quartz grain surface textures: a statistical investigation

Abstract: The relative abundance of thirty-two surface features identified on the surfaces of quartz sand grains from eight coded samples was noted independently by five scanning electron microscopists. These data (reduced to binary form) were the subject of canonical variate analyses which discriminated clearly between all samples. Thirteen variables were important in distinguishing between the eight samples. This indicates that there are no single key surface features which, on their own, would allow rapid environmental discrimination. The contention that a multiplicity of surface features should be recorded for the purpose of environmental discrimination is, therefore, upheld. Operator variance, although considerable in the recognition of individual surface features, is negligible in discrimination of samples based on binary data. The SEM technique of analysis of quartz grain surface textures is a reliable and statistically valid means of discriminating between samples from different environments.

The Magnitude and Frequency of Large Rockslides in Iceland in the Postglacial

Abstract: Data on large rockslides presented in a book by Olafur Jonsson (1976) are analyzed in terms of their magnitude and frequency in the Postglacial (10 000 a BP). Size has been examined by divi...

Clinical evaluation of org nc 45

Abstract: Org NC 45, a new non-depolarizing neuromuscular blocking drug, was evaluated in 200 adult patients. The drug was administered in doses of 0.1, 0.15 or 0.2 mg kg −1 . Intubation could be satisfactorily carried out at around 90s in 90% of patients. The duration of clinical relaxation varied from 23 min with 0.1 mgkg −1 and neuroleptanaesthesia to 71 min with 0.2 mg kg −1 and anaesthesia with halothane or enflurane. The duration of clinical relaxation following repeated administration of 2 – 3 mg was remarkably constant (between 17 and 20 min) thus showing lack of cumulation. The antagonism of residual block was prompt and easy following administration of neostigmine, and the drug lacked any significant cardiovascular effects as seen by routine monitoring

The effects of liming and soil pH on carbon and nitrog contained in the soil biomass

Abstract: The C and N in the biomass of soils from eight grassland field experiments where lime had been applied was determined by the chloroform fumigation method. Lime application increased C and N in the biomass by approximately 30% overall, although there was no effect at two sites. In the unlimed plots basal CO2 production, biomass C, and flush of mineral N production (FN) increased with soil pH. Biomass C and FN were correlated with total N content but not with organic C.Differences in the apparent C/N ratio of the biomass were found in unlimed soils of pH ≤ 4·5 and in those of pH > 4·5, the ratios being 4·2 and 5·8 respectively. For limed soils the ratio was 5·2. It is probable that the chloroform fumigation method is not suited to soils of very low pH, and that the C/N ratio obtained in soils of pH < 4·5 is artificially low.

Climate reconstruction from tree rings: Part 1, basic methodology and preliminary results for England

Abstract: Ring widths of oak trees from a network of 14 sites (13 in the British Isles and one in France) are used to reconstruct spatially averaged temperature and rainfall for England. A multiple linear regression technique is used, in which the regressors are orthogonal principal components of the ring widths. The multiple correlation coefficients are, statistically, highly significant, and the regression models' stability has been confirmed using independent data. These results demonstrate the usefulness of tree-ring widths for climate reconstruction in temperate, maritime areas.

Agricultural Progress in Medieval England: Some Evidence from Eastern Norfolk

Abstract: Thirteenthand fourteenth-century English agriculture is currently held in low repute. According to M. M. Postan "the inertia of medieval agricultural technology is unmistakable with the result that an agricultural system persisted in which the arable and pastoral sectors were competitive rather than complementary. As J. Z. Titow has observed, "a chronic state of under-manuring . . . would go a long way towards explaining the low level of productivity generally prevalent on the Winchester manors", and since stocking levels were probably even lower on peasant holdings, few would dissent from Postan's assertion that "we could not expect the villagers' output per acre to equal that of a well-managed demesne in the same locality".2 When, as in the thirteenth century, agriculture of such a low level of proficiency had to feed a steadily increasing population it is hardly surprising that events eventually followed a Malthusian course. This interpretation of the crisis which terminated the demographic and economic upswing of the early middle ages has been stated most succinctly by J. D. Chambers:

Central effects of beta-adrenoceptor antagonists

Abstract: The central effects of atenolol, a cardioselective beta-adrenoceptor antagonist, were investigated in six healthy men. Two flash-fusion threshold (2FFT), simple reaction time (SRT), digital copying (DCT), symbol-digit modalities (SDMT), and Gibson's spiral maze tests (GSMT) and mood rating scales for tension, alertness, depression, detachment, and anxiety were used. Each subject took 50, 100, 200, and 400 mg atenolol and identical placebo orally in a randomized, double-blind, crossover study and the psychomotor tests were performed at 0, 2, 3, 5, and 8 hr. 2FFT was prolonged at 3 hr after all doses and at 2 and 5 hr with 100, 200, and 400 mg. The maximum effect was achieved with 200 mg and mean 2FFT correlated with mean plasma atenolol concentration. SRTs were prolonged after all doses at between 2 and 5 hr. The DCT and the retest gain of the SDMT were both lower than after placebo at 2 hr with 100, 200, and 400 mg. The time taken to perform the GSMT was not altered by active drug, but the number of errors was lower at 2 hr with 100 and 200 mg. The self-rating mood scales showed a subjective decrease in tension 2 hr after 400 mg. The results show that atenolol exerts central effects in man.

Fasciola hepatica: development of monoclonal antibodies and their use to characterize a glycocalyx antigen in migrating flukes.

Abstract: Using mice harbouring early Fasciola hepatica infections, six monoclonal antibodies were prepared against a tegumental antigen present in T1 granules and glycocalyx of flukes. Blocking tests indicated that all monoclonals bound the same T1 epitope (or epitopes in close proximity on the antigen molecule), but this was not the determinant recognized by sheep and cattle. Localization of antibody binding at light and electron microscope levels showed that T1-type antigen also occurred in metacercarial tegument and in glycocalyx of gut cells and excretory ducts in juvenile and adult flukes. This indicates that the natural host-antibody response to F. hepatica may be to one antigen early in the infection. Protein A-gold labelling of monoclonal treated fluke sections revealed that the epitope was probably a polypeptide, unmodified by glycosylation in Golgi bodies. When isolated by immunoadsorption and separated electrophoretically under reducing conditions T1-type antigen was found to consist of a polypeptide mol. wt. 50 000, possibly linked to smaller entities mol. wt. 25-40 000. Tissue-specific variations in the antigen molecule might be conferred by linkage of different polypeptides or carbohydrate side-chains to an antigenic core polypeptide. A component of T1-type antigen was found to have mol. wt. of 25 000, possibly resembling a polypeptide of mol. wt. 24 000 from Schistosoma mansoni tegument.

A Role for Pectinase and Protease Inhibitors in Fungal Rot Development in Tomato Fruits

Abstract: B. cinerea and C. atramentarium rotted wound-inoculated green tomato fruits and wounded or intact ripe fruits while G. cingulata developed rots only in ripe fruits. Pectic en-zymes were extracted from the fruit tissue rotted by B. cinerea and C. atramentarium but no pectic enzymes attributable to the fungus were detected in ripe fruits rotted by G. cingulata. G. cingulata produced endo-PG and endo-PL in vitro, C. atramentarium produced endo-PL in vitro and in vivo and B. cinerea produced exo-PG in vitro and in green fruits but endo-PG and endo-PL in ripe fruits. Well ripened tomato fruits contained high levels of endogenous PG. All three fungi produced proteolytic enzymes in vitro and in vivo. Proteases produced by G. cingulata and C. atramentarium had optimum activity at pH 9 to 10 and were not trypsin-like or chymotrypsin-like in nature. Protease produced by B. cinerea had optimum activity at pH 7 and showed both trypsin and chymotrypsin-like activity. Proteins extracted from the cell walls of tomato fruits inhibited both the endo-PG and endo-PL produced by G. cingulata and the endo-PL produced by B. cinerea but did not in-hibit the activity of PGs produced by B. cinerea, the endo-PL produced by C. atramentarium or the endogenous PG from tomato fruits. The cell wall proteins also contained trypsin and chymotrypsin inhibitor activity which inhibited 70 % of the activity of the protease produced by B. cinerea, but had little effect on the proteases produced by G. cingulata, C. atramentarium or the tomato endogenous protease. Enzymes produced in vitro by G. cingulata macerated green tomato tissue more slowly than enzymes produced in vitro by C. atramentarium and B. cinerea and the rate of mation was further reduced in the presence of added cell wall proteins. Excess inhibitor of the little effect on the rate of maceration by the enzymes produced by C. atramentarium of the cinerea.

X-ray line ratios from helium-like ions - Updated theory and SMM flare observations

Abstract: The potential which the conduction of measurements of the three principal lines emitted from helium-like ions has for the determination of plasma electron density was initially pointed out by Gabriel and Jordan (1969). The diagnostic technique is based on the fact that the ratio, R, of the intensity of a forbidden line to the intensity of an intercombination line decreases as electron density increases due to collisional excitation of levels. In the present investigation a further refinement of this procedure is provided by specifically calculating the effects of cascades from levels with principal quantum numbers up to n=6. Two improved spectrometers recently placed in operation include the SOLEX instrument on the satellite P78-1 and the X-ray Polychromator (XRP) instrument on the NASA Solar Maximum Mission satellite. Measurements obtained with one of the spectrometers making up the XRP are presented, taking into account the emission from Ne IX ions.

Ranitidine as an antacid before elective Caesarean section

Abstract: In a preliminary study, 20 women in labour received ranitidine 50 mg intravenously. No significant changes were seen in the height, frequency or amplitude of uterine contractions or in fetal heart rate or pattern. No neonatal problems attributable to ranitidine were found. Ranitidine crossed the placenta, the mean fetal-maternal ratio being 0.9. Levels in the infants 12 hours following delivery were all very low. Ranitidine 150 mg orally was given to 80 healthy women undergoing elective Caesarean section at varying times from 75 to 510 minutes pre-operatively. From 2 to 6 hours following ingestion, the pH of gastric contents was greater than 2.5 in all but one patient. The mean volume aspirated (8 ml) was significantly lower than in a control group receiving magnesium trisilicate (mean volume 30 ml). Neonatal assessment included Apgar scoring, neurobehavioural examination, feeding progress, measurement of acidity and culture of gastric aspirates. No significant differences between groups were found. Blood levels indicated that the oral drug is readily absorbed by the parturient and that a smaller proportion is transferred to the fetus, mean fetal-maternal ratio at delivery being 0.38.