Substituting carbohydrate at lunch for added protein increases fat oxidation during subsequent exercise in healthy males

CONTEXT

How pre-exercise meal composition influences metabolic and health responses to exercise later in the day is currently unclear.

OBJECTIVE

Examine the effects of substituting carbohydrate for protein at lunch on subsequent exercise metabolism, appetite, and energy intake.

METHODS

Twelve healthy males completed three trials in randomized, counterbalanced order. Following a standardized breakfast (779 ± 66 kcal; ∼08:15), participants consumed a lunch (1186 ± 140 kcal; ∼13:15) containing either 0.2 g·kg-1 carbohydrate and ∼2 g·kg-1 protein (LO-CARB), 2 g·kg-1 carbohydrate and ∼0.4 g·kg-1 protein (HI-CARB), or fasted (FAST). Participants later cycled at ∼60% V̇O2peak for 1 h (∼16:15) and post-exercise ad-libitum energy intake was measured (∼18:30). Substrate oxidation, subjective appetite, and plasma concentrations of glucose, insulin, non-esterified fatty acids (NEFA), peptide YY (PYY), glucagon-like peptide-1 (GLP-1), and acylated ghrelin (AG) were measured for 5 h post-lunch.

RESULTS

Fat oxidation was greater during FAST (+11.66 ± 6.63 g) and LO-CARB (+8.00 ± 3.83 g) than HI-CARB (p < 0.001), with FAST greater than LO-CARB (+3.67 ± 5.07 g; p < 0.05). NEFA were lowest in HI-CARB and highest in FAST, with insulin demonstrating the inverse response (all p < 0.01). PYY and GLP-1 demonstrated a stepwise pattern, with LO-CARB greatest and FAST lowest (all p < 0.01). AG was lower during HI-CARB and LO-CARB versus FAST (p < 0.01). Energy intake in LO-CARB was lower than FAST (-383 ± 233 kcal; p < 0.001) and HI-CARB (-313 ± 284 kcal; p < 0.001).

CONCLUSION

Substituting carbohydrate for protein in a pre-exercise lunch increased fat oxidation, suppressed subjective and hormonal appetite, and reduced post-exercise energy intake.

Determining factors of physical activity and sedentary behaviour in university students during the COVID-19 pandemic: A longitudinal study

INTRODUCTION

Historically, university students demonstrate poor movement behaviours that could negatively impact current and future health. Recent literature has focused on identifying determinants of physical activity (PA) and sedentary behaviour (SB) in this population to inform the development of intervention strategies. However, the COVID-19 pandemic substantially restricted movement behaviours in this population, meaning findings of previous research may no longer be applicable within the current societal context. The present study explored the longitudinal relationships between pre-pandemic psychological, behavioural and anthropometric factors, and the movement behaviours of UK university students nine months following the outbreak of COVID-19.

METHODS

Mental wellbeing (MWB), perceived stress (PS), body mass index (BMI), SB, and PA were assessed using an online self-report survey in 255 students prior to (October 2019) and nine months following (October 2020) the first confirmed case of COVID-19 in the UK. Path analysis was utilised to test relationships between pre-COVID mental wellbeing, perceived stress and BMI, and movement behaviours during the pandemic.

RESULTS

The fit of the path analysis model was good (χ2 = 0.01; CMIN = 0.10, CFI = 1.00, RMSEA = 0.00). Pre-covid MWB and PS positively influenced PA (β = 0.29; β = 0.24; P < 0.01) but not SB (β = -0.10; β = 0.00; P = 0.79) during the pandemic. Additionally, pre-pandemic SB and PA positively influenced SB and PA during the pandemic respectively (SB: β = 0.26; P < 0.01) (PA: β = 0.55; P < 0.01). Pre-pandemic BMI did not influence any measured variable during the pandemic (PA: β = 0.03 and P = 0.29; SB: β = 0.06 and P = 0.56), and there was no mediating effect of PA on SB during the pandemic (β = -0.26; P = 0.14).

CONCLUSION

These findings indicate that pre-covid mental health and movement behaviours had a direct positive influence on PA during the pandemic, but not SB. This longitudinal study demonstrates the influence that prior psychological and behavioural factors have in determining university students' response to periods of elevated stress and uncertainty, furthering our understanding of determinants of health-related behaviours in students.

Combined Turmeric, Vitamin C, and Vitamin D Ready-to-Drink Supplements Reduce Upper Respiratory Illness Symptoms and Gastrointestinal Discomfort in Elite Male Football Players

Elite football is associated with the increased risk of illness, although targeted supplementation can reduce illness risk. This study assessed the effects of a supplement containing turmeric root within a black pepper and fat-soluble blend, vitamin C and vitamin D, on upper respiratory symptoms (URS), gastrointestinal symptoms (GIS), muscle soreness, and markers of inflammation and gut permeability in elite male footballers. Twenty-three footballers completed 3 weeks of no intervention (CON), followed by 16 weeks of daily consuming 60 mL of a commercially available supplement containing raw turmeric root (17.5 g, estimated to contain 700 mg of curcumin), vitamin C (1000 mg), and vitamin D3 (3000 IU/75 mcg) (SUP). URS and GIS were measured daily. Immediately (0 h), 40, and 64 h after six competitive matches (two in CON, four in SUP), the subjective soreness and plasma concentrations of creatine kinase [CK], c-reactive protein [CRP], and intestinal fatty-acid binding protein [I-FABP] were assessed. URS incidence (p < 0.001), GIS (p < 0.05), and plasma [I-FABP] at 0 h (p < 0.05) were greater during CON versus SUP. At 40 h, [CRP] was greater than 0 h during CON (p < 0.01) but not SUP (p = 0.204). There were no differences in soreness or [CK]. This study indicates that turmeric root, vitamin C, and vitamin D supplementation over 16 weeks can reduce URS, GIS, and post-match [I-FABP] in elite footballers.

Turmeric supplementation improves markers of recovery in elite male footballers: a pilot study

Football match-play causes muscle damage and provokes an inflammatory response. Rapid recovery is paramount to optimising subsequent performance and reducing injury risk. Turmeric contains high concentrations of curcumin, a polyphenol that has been shown to reduce muscle damage and soreness post-exercise in recreational exercisers. However, it is unknown whether a curcumin-containing supplement can support elite footballers recovery between matches. This applied study explored whether a turmeric supplement could improve performance, subjective and physiological markers of recovery, in elite male footballers. Twenty-four elite male footballers divided into a turmeric group, who consumed 60 mL of a turmeric drink twice per day, or a control group who did not. After 96 h of rest, baseline measurements of subjective soreness (leg and whole-body), plasma creatine kinase ([CK]), plasma C-reactive protein ([CRP]), isometric mid-thigh pull (IMTP) and counter movement jump (CMJ), were collected. Following eight competitive matches, subjective leg and whole-body soreness and plasma concentrations of inflammation markers ([CK] and [CRP]) were assessed immediately (0 h), 40 and 64 h post-match. Performance markers (IMTP and CMJ) were also assessed at 40 and 64 h post-match. Percentage change from baseline showed a main effect of group (p = 0.035, p = 0.005) and time (p = 0.002, p = 0.002) for both leg and whole-body soreness, respectively. There was a group by time interaction effect (p = 0.049) for [CRP]. There were no effects of turmeric on [CK], CMJ or IMTP. This applied study is the first in elite footballers to show that a curcumin-containing supplementation may attenuate a biomarker of inflammation [CRP] and soreness post-match play.

Effects of Morning Vs. Evening exercise on appetite, energy intake, performance and metabolism, in lean males and females

Exercise is an important component of a weight management strategy. However, little is known about whether circadian variations in physiological and behavioural processes can influence the appetite and energy balance responses to exercise performed at different times of the day. This study compared the effects of morning and evening exercise on appetite, post-exercise energy intake, and voluntary performance. In randomised, counterbalanced order, 16 healthy males and females (n = 8 each) completed two trials, performing morning exercise at 10:30 (AMEx) or evening exercise at 18:30 (PMEx). Exercise consisted of 30 min steady-state cycling (60% V˙ O_2peak), and a 15-min performance test. A standardised meal (543 ± 86 kcal) was consumed 2-h before exercise and ad-libitum energy intake was assessed 15 min after exercise, with subjective appetite measured throughout. Absolute ad-libitum energy intake was 152 ± 126 kcal greater during PMEx (P < 0.001), but there was no differences in subjective appetite between trials immediately pre-exercise, or immediately before the post-exercise meal (P ≥ 0.060). Resting energy expenditure (P < 0.01) and carbohydrate oxidation (P < 0.05) were greater during AMEx, but there were no differences in substrate oxidation or energy expenditure during exercise (P ≥ 0.155). Exercise performance was not different between trials (P = 0.628). In conclusion, acute morning and evening exercise prompt similar appetite responses, but post-exercise ad-libitum energy intake is greater following evening exercise. These findings demonstrate discordant responses between subjective appetite and ad-libitum energy intake but suggest that exercise might offset circadian variations in appetite. Longer-term studies are required to determine how exercise timing affects adherence and weight management outcomes to exercise interventions. TRIAL REGISTRATION: NCT04742530, February 8, 2021.

Effect of the perception of breakfast consumption on subsequent appetite and energy intake in healthy males

Purpose

This study aimed to assess the effects of consuming a very-low-energy placebo breakfast on subsequent appetite and lunch energy intake.

Methods

Fourteen healthy males consumed water-only (WAT), very-low-energy, viscous placebo (containing water, low-calorie flavoured squash, and xanthan gum; ~ 16 kcal; PLA), and whole-food (~ 573 kcal; FOOD) breakfasts in a randomised order. Subjects were blinded to the energy content of PLA and specific study aims. Venous blood samples were collected pre-breakfast, 60- and 180-min post-breakfast to assess plasma acylated ghrelin and peptide tyrosine tyrosine concentrations. Subjective appetite was measured regularly, and energy intake was assessed at an ad libitum lunch meal 195-min post-breakfast.

Results

Lunch energy intake was lower during FOOD compared to WAT (P < 0.05), with no further differences between trials (P ≥ 0.132). Cumulative energy intake (breakfast plus lunch) was lower during PLA (1078 ± 274 kcal) and WAT (1093 ± 249 kcal), compared to FOOD (1554 ± 301 kcal; P < 0.001). Total area under the curve (AUC) for hunger, desire to eat and prospective food consumption were lower, and fullness was greater during PLA and FOOD compared to WAT (P < 0.05). AUC for hunger was lower during FOOD compared to PLA (P < 0.05). During FOOD, acylated ghrelin was suppressed compared to PLA and WAT at 60 min (P < 0.05), with no other hormonal differences between trials (P ≥ 0.071).

Conclusion

Consuming a very-low-energy placebo breakfast does not alter energy intake at lunch but may reduce cumulative energy intake across breakfast and lunch and attenuate elevations in subjective appetite associated with breakfast omission.

Trial registration

NCT04735783, 2nd February 2021, retrospectively registered.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00394-021-02727-5.

Insulin stimulates β-alanine uptake in skeletal muscle cells in vitro

We evaluated whether insulin could stimulate β-alanine uptake by skeletal muscle cells in vitro. Mouse myoblasts (C2C12) (n = 3 wells per condition) were cultured with β-alanine (350 or 700 µmol·L^-1), with insulin (100 µU·mL^-1) either added to the media or not. Insulin stimulated the β-alanine uptake at the lower (350 µmol·L^-1) but not higher (700 µmol·L^-1) β-alanine concentration in culture medium, indicating that transporter saturation might blunt the stimulatory effects of insulin.

The effect of β-alanine supplementation on high intensity cycling capacity in normoxia and hypoxia

The availability of dietary beta-alanine (BA) is the limiting factor in carnosine synthesis within human muscle due to its low intramuscular concentration and substrate affinity. Carnosine can accept hydrogen ions (H⁺), making it an important intramuscular buffer against exercise-induced acidosis. Metabolite accumulation rate increases when exercising in hypoxic conditions, thus an increased carnosine concentration could attenuate H⁺ build-up when exercising in hypoxic conditions. This study examined the effects of BA supplementation on high intensity cycling capacity in normoxia and hypoxia. In a double-blind design, nineteen males were matched into a BA group (n = 10; 6.4 g·d^-1) or a placebo group (PLA; n = 9) and supplemented for 28 days, carrying out two pre- and two post-supplementation cycling capacity trials at 110% of powermax, one in normoxia and one in hypoxia (15.5% O₂). Hypoxia led to a 9.1% reduction in exercise capacity, but BA supplementation had no significant effect on exercise capacity in normoxia or hypoxia (P > 0.05). Blood lactate accumulation showed a significant trial x time interaction post-supplementation (P = 0.016), although this was not significantly different between groups. BA supplementation did not increase high intensity cycling capacity in normoxia, nor did it improve cycling capacity in hypoxia even though exercise capacity was reduced under hypoxic conditions.

Does Hypohydration Really Impair Endurance Performance? Methodological Considerations for Interpreting Hydration Research

The impact of alterations in hydration status on human physiology and performance responses during exercise is one of the oldest research topics in sport and exercise nutrition. This body of work has mainly focussed on the impact of reduced body water stores (i.e. hypohydration) on these outcomes, on the whole demonstrating that hypohydration impairs endurance performance, likely via detrimental effects on a number of physiological functions. However, an important consideration, that has received little attention, is the methods that have traditionally been used to investigate how hypohydration affects exercise outcomes, as those used may confound the results of many studies. There are two main methodological limitations in much of the published literature that perhaps make the results of studies investigating performance outcomes difficult to interpret. First, subjects involved in studies are generally not blinded to the intervention taking place (i.e. they know what their hydration status is), which may introduce expectancy effects. Second, most of the methods used to induce hypohydration are both uncomfortable and unfamiliar to the subjects, meaning that alterations in performance may be caused by this discomfort, rather than hypohydration per se. This review discusses these methodological considerations and provides an overview of the small body of recent work that has attempted to correct some of these methodological issues. On balance, these recent blinded hydration studies suggest hypohydration equivalent to 2–3% body mass decreases endurance cycling performance in the heat, at least when no/little fluid is ingested.

Effect of carbohydrate feeding on the bone metabolic response to running

Bone resorption is increased after running, with no change in bone formation. Feeding during exercise might attenuate this increase, preventing associated problems for bone. This study investigated the immediate and short-term bone metabolic responses to carbohydrate (CHO) feeding during treadmill running. Ten men completed two 7-day trials, once being fed CHO (8% glucose immediately before, every 20 min during, and immediately after exercise at a rate of 0.7 g CHO·kg body mass⁻¹·h⁻¹) and once being fed placebo (PBO). On day 4 of each trial, participants completed a 120-min treadmill run at 70% of maximal oxygen consumption (V̇o_{2 max}). Blood was taken at baseline (BASE), immediately after exercise (EE), after 60 (R1) and 120 (R2) min of recovery, and on three follow-up days (FU1-FU3). Markers of bone resorption [COOH-terminal telopeptide region of collagen type 1 (β-CTX)] and formation [NH₂-terminal propeptides of procollagen type 1 (P1NP)] were measured, along with osteocalcin (OC), parathyroid hormone (PTH), albumin-adjusted calcium (ACa), phosphate, glucagon-like peptide-2 (GLP-2), interleukin-6 (IL-6), insulin, cortisol, leptin, and osteoprotogerin (OPG). Area under the curve was calculated in terms of the immediate (BASE, EE, R1, and R2) and short-term (BASE, FU1, FU2, and FU3) responses to exercise. β-CTX, P1NP, and IL-6 responses to exercise were significantly lower in the immediate postexercise period with CHO feeding compared with PBO (β-CTX: P = 0.028; P1NP: P = 0.021; IL-6: P = 0.036), although there was no difference in the short-term response (β-CTX: P = 0.856; P1NP: P = 0.721; IL-6: P = 0.327). No other variable was significantly affected by CHO feeding during exercise. We conclude that CHO feeding during exercise attenuated the β-CTX and P1NP responses in the hours but not days following exercise, indicating an acute effect of CHO feeding on bone turnover.

The investigation of infants with RhD-negative mothers: can we safely omit the umbilical cord blood direct antiglobulin test?

Historically, the investigation of a neonate at risk of Rhesus D antigen (RhD)-associated haemolytic disease has included a direct antiglobulin test on umbilical cord blood. However, the introduction of routine antenatal anti-RhD prophylaxis has led to a significant number of false positive results and recent studies suggest that a positive cord blood direct antiglobulin test is poorly predictive of subsequent hyperbilirubinaemia. The British Committee for Standards in Haematology guidelines now recommend that a direct antiglobulin test should no longer be performed routinely on umbilical cord blood in infants born to RhD-negative mothers. We review the recent changes in antenatal management of RhD-negative mothers and their impact on the neonatal presentation of RhD-associated haemolytic disease of the newborn that underpin this recommendation. We conclude that there is convincing evidence to support the guidelines. Finally, we consider how babies born to RhD-negative mothers should be investigated and consider alternative strategies to detect neonatal hyperbilirubinaemia.

Two Georgian fathers: diverse in experience, united in grief

The history of paediatrics and child health is increasingly recognised to be about children themselves and how they and their families cope and adapt to their medical condition rather than about medical practitioners and august institutions. This article considers two case studies, showing how two Georgian fathers cared for their children when sickness struck and their reactions when the children died. Davies (Giddy) Gilbert, FRS (1767-1840), was a member of Parliament first for Helston and later for Bodmin. (He married Ann Mary Gilbert in 1808 and formally changed his name to Gilbert; the change received royal approbation in January 1817.) Gilbert recorded the birth and development of his son Charles (1810-1813), in one of the very earliest developmental chronicles. He regularly recorded his child's progress, including height, weight, social interaction, communication skills and speech. Apparently in good health for most of his life, Charles developed an acute abdominal disorder and died unexpectedly. John Tremayne (1780-1851) was a member of Parliament for Cornwall. His son Harry (1814-1823) had increasing bilious attacks, headaches and a squint from the age of 6 years, and died despite the best medical advice available. Current medical opinion would presume an intracranial tumour. Tremayne graphically expressed his pain as he closely observed his son suffer, apparently as much from the treatments as from the disease itself. This study sheds light on clinical aspects of Georgian medical practice, the medical marketplace and the nature of relationships between these fathers and their children.

The investigation and management of chronic neutropenia in children

Unravelling the cause of a neutropenia poses a complex diagnostic challenge. The differential diagnosis ranges from life threatening disease to transient benign causes of little clinical significance. This review offers a practical guide to investigating the neutropenic child, and highlights features that merit specialist referral. Therapeutic options, the role of long term follow up, and the complications of severe chronic neutropenia are considered.

Fulminant Crohn's colitis after allogeneic stem cell transplantation

We report a case of fulminant Crohn's colitis that occurred following non-myeloablative allogeneic stem cell transplantation for Hodgkin's lymphoma. Adoptive transfer of inflammatory bowel disease by haematopoietic cells is recognised in several animal models of inflammatory bowel disease and remission of Crohn's disease has been reported in patients who have received a bone marrow transplant. However, adoptive transfer of Crohn's disease susceptibility leading to phenotypic manifestation of the disease after transplantation has not been previously reported. Having ruled out an infective cause of a colitis in this case, we speculated that adoptive transfer of Crohn's disease may have occurred and performed a genetic analysis of known susceptibility loci for significant donor-recipient mismatches. The donor and recipient had several haplotype mismatches in HLA class III genes at the IBD3 locus. In addition, the donor (but not the recipient) had a polymorphism of the 5' UTR of NOD2/CARD15 that may be associated with Crohn's disease. This case highlights the question of whether adoptive transfer of Crohn's disease can occur between allogeneic stem cell transplant donor and recipient, in a similar fashion to that reported for other autoimmune diseases. This report should also stimulate debate regarding the need for stem cell transplant donor screening for inflammatory bowel disease.

Regulation of pulmonary and systemic bacterial lipopolysaccharide responses in transgenic mice expressing human elafin

The control of lung inflammation is of paramount importance in a variety of acute pathologies, such as pneumonia, the acute respiratory distress syndrome, and sepsis. It is becoming increasingly apparent that local innate immune responses in the lung are negatively influenced by systemic inflammation. This is thought to be due to a local deficit in cytokine responses by alveolar macrophages and neutrophils following systemic bacterial infection and the development of a septic response. Recently, using an adenovirus-based strategy which overexpresses the human elastase inhibitor elafin locally in the lung, we showed that elafin is able to prime lung innate immune responses. In this study, we generated a novel transgenic mouse strain expressing human elafin and studied its response to bacterial lipopolysaccharide (LPS) when the LPS was administered locally in the lungs and systemically. When LPS was delivered to the lungs, we found that mice expressing elafin had lower serum-to-bronchoalveolar lavage ratios of proinflammatory cytokines, including tumor necrosis factor alpha (TNF-alpha), macrophage inflammatory protein 2, and monocyte chemoattractant protein 1, than wild-type mice. There was a concomitant increase in inflammatory cell influx, showing that there was potential priming of innate responses in the lungs. When LPS was given systemically, the mice expressing elafin had reduced levels of serum TNF-alpha compared to the levels in wild-type mice. These results indicate that elafin may have a dual function, promoting up-regulation of local lung innate immunity while simultaneously down-regulating potentially unwanted systemic inflammatory responses in the circulation.

The impact of a 10-year audit cycle on blood usage in a district general hospital

As clinical governance moves from concept to practice, it is emerging as a realistic strategy to promote and improve quality within the National Health Service, as well as satisfying the demand for external accountability. In the context of blood transfusion, the area of responsibility encompasses product liability, as well as efficient use of blood as a resource and transfusion as an appropriate clinical response. Clinical governance may be a modern catch phrase, but the principles it enshrines have long been established within blood transfusion, and in other aspects of haematology. Here, an audit cycle comprising four audits over a 10-year period to monitor the use of cross-matched blood in a large district general hospital is described. Initially, blood use was considered by hospital site, and by the surgical procedure for which it was requested. Later, the scope of the audit was expanded to consider usage by individual consultant. A standard of efficient use of cross-matched blood was taken to be a cross-match to transfusion ratio of < 1.5. The information was reviewed by the hospital transfusion committee, who have a key role in co-ordinating and assessing the practice of transfusion within a hospital. In this hospital, audit has been one of the main tools for improving practice, in particular by enabling the implementation and continuous revision of a maximum blood order schedule. Further, as the process of audit has developed, problem areas have been highlighted, and strategies to improve usage have been brought in with encouraging results. The audit is now being expanded again to include a greater focus on usage of cross-matched blood in the nonsurgical setting.

Mutant K-ras enhances apoptosis in embryonic stem cells in combination with DNA damage and is associated with increased levels of p19(ARF)

The roles of K-ras in neoplasia are not entirely understood, although there is evidence that K-ras affects susceptibility to apoptosis, modulating survival of DNA damaged cells which would otherwise be eliminated. In this study, we investigated the effects of mutant K-ras on apoptosis in vitro following DNA damage. To avoid complications resulting from mutations in other cancer-related genes and from the presence of endogenous K-ras, we derived K-ras null embryonic stem cells. Expression of either wild-type or mutant K-ras was reconstructed by stable plasmid transfection. The cell lines were treated with etoposide, cisplatin and UV radiation and apoptosis measured flow cytometrically. Mutant K-ras potentiated the effect of etoposide-derived DNA damage by increasing apoptosis, whereas absence of K-ras had the opposite effect. This pattern was similar but less marked with cisplatin, whereas UV yielded no difference in apoptosis with regard to K-ras status, suggesting that the effect of K-ras on apoptosis is dependent on the nature of the DNA damage. To investigate possible mechanisms, we examined the expression of p19(ARF) mRNA by RT-PCR. Cells expressing mutant K-ras produced elevated levels of p19(ARF) mRNA, which could link K-ras status with p53 expression and hence susceptibility to DNA damage-induced apoptosis.

Multiple copies of beta-lactoglobulin promoter do not function as LCR

Increasing the number of transcription factor binding sites within a construct can enhance expression. In an attempt to create a synthetic locus control region for mammary expression, we have generated beta-lactoglobulin-reporter constructs with multiple copies of the cluster of transcription sites normally located within the proximal promoter. These constructs were functionally tested by stable transfection of mammary epithelial cells in vitro and in transgenic mice in vivo. Rather than enhancing expression, multimerisation of the promoter region acted neither in vivo nor in vitro to enhance expression. Indeed, its presence reduced expression. This failure to enhance expression was reflected in the inability of this region to form a DNaseI hypersensitive site autonomously in mammary chromatin in vivo. It is implicit from our study that not all combinations of transcription factor binding sites will enhance transcription.

Restricted distribution of tetraploid cells in mouse tetraploid<==>diploid chimaeras

Tetraploid mouse embryos were produced by electrofusion at the 2-cell stage, cultured overnight, and aggregated with normal diploid embryos to produce tetraploid<==>diploid (4n<==>2n) chimaeric conceptuses. At 7 1/2 days the 4n<==>2n chimaeras were usually smaller and developmentally retarded compared to control diploid<==>diploid chimaeras. At 12 1/2 days the 4n<==>2n chimaeras had heavier placentas but there was no significant difference in fetal size. Tetraploid cells showed a restricted tissue distribution at both developmental stages studied: 4n cells were commonly present in both the primitive endoderm and the trophectoderm lineages but they rarely contributed to the primitive ectoderm lineage. The overall similarity in the distribution of tetraploid cells at 7 1/2 and 12 1/2 days implies that whatever causes the restricted tissue distribution operates largely before 7 1/2 days. There was no evidence for excessive embryonic losses of 4n<==>2n chimaeras. So, if the restricted distribution of 4n cells was a result of cell selection, the mechanism is more likely to involve loss of 4n cells from the primitive ectoderm early in development rather than selective death of conceptuses with tetraploid cells in this lineage. Alternatively, 4n cells may be preferentially allocated to the trophectoderm and primitive endoderm rather than the primitive ectoderm layer at the blastocyst stage.

A chimaeric animal model for confined placental mosaicism

The reason for chromosome mosaicism being sometimes confined to only part of the conceptus is unknown. To address this problem, we produced tetraploid<-->diploid chimaeric mouse conceptuses. At 12 1/2 days, no tetraploid cells were detected in the fetus. They rarely contributed to other derivatives of the primitive ectoderm lineage but were commonly found in the primitive endoderm and trophectoderm lineages. This provides a useful animal model of human confined placental mosaicism and suggests that the primitive endoderm (hypoblast) lineage should be included in future studies of human mosaic conceptuses.

Electrofusion of mouse embryos results in uniform tetraploidy and not tetraploid/diploid mosaicism

Some previous attempts to produce tetraploids experimentally have resulted in a proportion of treated embryos becoming 2n/4n mosaics at a frequency which may be as high as 20%, when using cytochalasin B as a fusigenic stimulus and cytogenetic techniques to identify putative tetraploid embryos. To investigate the possible occurrence of 4n/2n mosaicism, tetraploid embryos were produced by electrofusion, a process which allows adjacent blastomeres at the 2-cell stage to fuse following exposure to electric field pulses. Embryos used for electrofusion were hemizygous for a transgene consisting of approximately 1000 copies of the mouse beta-globin gene. After in situ hybridization, one hybridization signal is expected per diploid genome. Tetraploid cells in 7.5-, 8.5-, 9.5- and 10.5-day-old conceptuses were distinguished from diploid cells by performing in situ hybridization on histological sections. The frequency of nuclei with two hybridization signals in the 'hemizygous' tetraploid embryos was compared to diploid embryos which were either hemizygous or homozygous for the beta-globin transgene. Comparison of the frequency of nuclei with two hybridization signals between tissues of 'hemizygous' tetraploid conceptuses and homozygous diploid conceptuses showed no significant difference, which implies that the tissues in the tetraploid conceptuses were uniformly tetraploid. No evidence was found to suggest that electrofusion results in 2n/4n mosaicism.

The problems of transferring software: a medical case history

This paper discusses the problems which arose in the transfer of a Pathology Laboratory data-base system from a CTL Mod 1 computer to a Ferranti Argus 700E computer. Both systems were programmed in CORAL-66. Definition of the analytical tests, the wards and clinics and G.P.'s addresses serviced by the laboratory proved to be a much larger task than had been anticipated. The mirroring of the comparative facilities of the two hardware systems is also described.

A computerized scheme for the preparation of parenteral nutrition regimes

An operational computerized system to aid clinicians in the design of total parenteral nutrition regimes is reported. Two computer programs are described. The 'Requirements' program uses patient data and the results of blood and fluid excretion analyses to calculate the nutritional requirements for a period of 24 hours. Accepted formulae are used in these calculations. The 'Bottle Selection' program fits an intravenous bottle regime to the patient requirements from a standard set of commercially available intravenous feeding solutions. The system has been well accepted by the clinical staff who are free to accept, modify or reject a regime. Financial savings have been noted by the pharmacy who can plan for a faster turnover of a smaller range of solutions. The programs have been used routinely on a programmable calculator and have been written in CORAL for a Ferranti Argus 700E computer.

An off-line data processing system for biochemistry profiling based on a 2K programmable calculator

An off-line data processing system based on a Hewlett Packard 2K programmable calculator to be used with a biochemistry profiling system is described. The program is in two sections. A Data Acquisition phase calculates results from Auto Analyser II peak heights after corrections for drift and stores them on magnetic tape cassettes. Quality control statistics are produced. A Reporting phase types the profile results on self-adhesive pre-printed labels to be attached to the test-request form and also prepares a laboratory record sheet. The system is routinely used to process up to 2000 peak heights per day. Non-profile heights may also be read using this program.

Rat gastric acid secretion studies with histamine and synthetic gastrin-like pentapeptide

1. Gastric acid secretion was measured in the urethane anaesthetized rat whilst maintaining a recirculated gastric perfusion fluid at pH 4.2. The latent period of onset of secretion following single intravenous doses of histamine and pentapeptide in combination was significantly shorter than that following either stimulant alone.3. When administered over a period of 2 hr the maximal steady rate of secretion in response to pentapeptide was 75% of that to histamine.4. Acid stimulatory effects were additive both when the drugs were given concurrently over a 2 hr period and when one was administered after a maximal response had been obtained to the other.5. Although there is some evidence to indicate that histamine and pentapeptide might be initiating acid secretion by different mechanisms it is suggested that they may not be acting with total independence.

Influence of intragastric pH on electrolyte secretion by the guinea-pig stomach

1. A technique is described for the continuous assessment of acid secretion by the guinea-pig gastric mucosa at selected levels of intragastric pH.2. The rate of hydrogen ion secretion increases linearly with pH over the intragastric range of pH 4.4 to 9.4. Sodium and potassium secretions are not clearly related to pH. Outputs of both chloride and bicarbonate rise as pH is increased.3. The carbonic anhydrase inhibitor acetazolamide reversibly reduces rapid rates of acid secretion as occur when gastric contents are maintained at pH 10.4. Alkali stimulated acid output is not inhibited by atropine (2 mg/kg) and probably results directly from increased carbonic anhydrase activity as the in vitro activity of the enzyme may be correlated with the rate of acid secretion over a wide range of pH.